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Sample records for magnetic spreading anomalies

  1. Seafloor spreading in the eastern Gulf of Mexico: New evidence for marine magnetic anomalies

    NASA Astrophysics Data System (ADS)

    Eskamani, Philip K.

    Possible sea-floor spreading anomalies are indentified in marine magnetic surveys conducted in the eastern Gulf of Mexico. A symmetric pattern of lineated anomalies can be correlated with the geomagnetic time scale using previously proposed opening histories for the Gulf of Mexico basin. Lineated magnetic anomalies are characterized by amplitudes of up to 30 nT and wavelengths of 45-55 km, and are correlatable across 12 different ship tracks spanning a combined distance of 6,712 km. The magnetic lineations are orientated in a NW-SE direction with 3 distinct positive lineations on either side of the inferred spreading ridge anomalies. The magnetic anomalies were forward modeled with a 2 km thick magnetic crust composed of vertically bounded blocks of normal and reverse polarity at a model source depth of 10 km. Remnant magnetization intensity and inclination are 1.6 A m-1 and 0.2° respectively, chosen to best fit the magnetic observed amplitudes and, for inclination, in accord with the nearly equatorial position of the Gulf of Mexico during Jurassic seafloor spreading. The current magnetic field is modeled with declination and inclination of and 0.65° and 20° respectively. Using a full seafloor spreading rate of 1.7 cm/yr, the anomalies correlate with magnetic chrons M21 to M10. The inferred spreading direction is consistent with previous suggestions of a North-East to South-West direction of sea-floor spreading off the west coast of Florida beginning 149 Ma (M21) and ending 134 Ma (M10). The opening direction is also consistent with the counter-clockwise rotation of Yucatan proposed in past models.

  2. Contribution of oceanic gabbros to sea-floor spreading magnetic anomalies.

    PubMed

    Kikawa, E; Ozawa, K

    1992-10-30

    The contribution of oceanic gabbros, representative rocks for layer 3 of the oceanic crust, to sea-floor spreading magnetic anomalies has been controversial because of the large variation in magnetic properties. Ocean Drilling Program (ODP) Leg 118 contains a continuous 500.7-meter section of oceanic gabbro that allows the relations between magnetization and petrologic characteristics, such as the degree of metamorphism and the magmatic evolution, to be clarified. The data suggest that oceanic gabbros, together with the effects of metamorphism and of magmatic evolution, account for a significant part of the marine magnetic anomalies. PMID:17777035

  3. A New Seafloor Spreading Model of the Red Sea: Magnetic Anomalies and Plate Kinematics

    NASA Astrophysics Data System (ADS)

    Dyment, J.; Tapponnier, P.; Afifi, A. M.; Zinger, M. A.; Franken, D.; Muzaiyen, E.

    2013-12-01

    A high resolution aeromagnetic survey over the Saudi Arabian side of the Red Sea confirms the existence of consistent magnetic anomaly patterns, continuous from 16 to 24°N, and episodic up to 28°N, typical of slow to ultraslow spreading centers. The older Saudi-Sudanese aeromagnetic survey shows that these anomalies are symmetrical between 18 and 23°N. The strong, short-wavelength anomalies over the central trough south of 24°N have long been identified as Chrons 1 to 3 (0-5 Ma). By contrast, the weaker, longer-wavelength anomalies over adjacent sediment-covered areas do not fit standard magnetic anomaly models. The abrupt basement deepening from ~ 1.5 km in the central trough to ~ 5 km beneath the sediments partly accounts for the lower amplitude but not for the lack of short wavelengths. Other spreading centers also lack short-wavelength, high-amplitude magnetic anomalies where covered by thick sediments (Andaman Basin, Juan de Fuca Ridge). We interpret this to reflect the absence of a well-defined layer of pillow lavas, whose emplacement is hampered by rapid, abundant sedimentation. The formation of dykes and sills instead of extrusive lavas results in weaker, less coherent magnetization, generating longer-wavelength anomalies. We test this inference by removing the extrusive basalt contribution from a slow spreading center crustal magnetization model. The computed magnetic anomalies fit well with the shape and amplitude of the anomalies observed in the Red Sea. Two major long-wavelength anomalies are dated at 10-11 Ma (Chron 5) and 14-15 Ma (Chron 5B), implying seafloor spreading back to at least 15 Ma and constraining plate-kinematic reconstructions. Beyond being a key to the geological evolution of the Red Sea, these results emphasize that oceanic crust may exist without clear, short wavelength magnetic anomalies, particularly at the onset of seafloor spreading, when abundant sedimentation may preclude the formation of pillow lavas. The location of many inferred ocean-continent boundaries, particularly beneath thick evaporite sequences, should therefore be revisited, alleviating the need for 'transitional' crust and allowing for a tighter fit of continents in initial reconstructions.

  4. Early India-Australia Spreading History Revealed by Newly Detected Magnetic Anomalies

    NASA Astrophysics Data System (ADS)

    Williams, S.; Whittaker, J. M.; Granot, R.; Müller, D.

    2013-12-01

    The seafloor within the Perth Abyssal Plain (PAP), offshore Western Australia, is the only section of crust that directly records the early spreading history between India and Australia during the Mesozoic breakup of Gondwana. However, this early spreading has been poorly constrained due to an absence of data, including marine magnetic anomalies and data constraining the crustal nature of key tectonic features. Here, we present new magnetic anomaly data from the PAP that shows that the crust in the western part of the basin was part of the Indian Plate - the conjugate flank to the oceanic crust immediately offshore the Perth margin, Australia. We identify a sequence of M2 and older anomalies in the west PAP within crust that initially moved with the Indian Plate, formed at intermediate half-spreading rates (35 mm/yr) consistent with the conjugate sequence on the Australian Plate. More speculatively, we reinterpret the youngest anomalies in the east PAP, finding that the M0-age crust initially formed on the Indian Plate was transferred to the Australian Plate by a westward jump or propagation of the spreading ridge shortly after M0 time. Samples dredged from the Gulden Draak and Batavia Knolls (at the western edge of the PAP) reveal that these bathymetric features are continental fragments rather than igneous plateaus related to Broken Ridge. These microcontinents rifted away from Australia with Greater India during initial breakup at ~130 Ma, then rifted from India following the cessation of spreading in the PAP (~101-103 Ma).

  5. Investigation of spreading center ecolution by joint inversion of seafloor magnetic anomaly and tectonic fabric data

    NASA Technical Reports Server (NTRS)

    Shoberg, Tom; Stein, Seth

    1994-01-01

    Spreading center segments that have experienced a complex tectonic history including rift propagation may have a complicated signature in bathymetric and magnetic anomaly data. To gain insight into the history of such regions, we have developed techniques in which both the magnetic anomaly patterns and seafloor fabric trends are predicted theoretically, and the combined predictions are compared numerically with the data to estimate best fitting parameters for the propagation history. Fitting functions are constructed to help determine which model best matches the digitized fabric and magnetic anomaly data. Such functions offer statistical criteria for choosing the best fit model. We use this approach to resolve the propagation history of the Cobb Offset along the Juan de Fuca ridge. In this example, the magnetic anomaly data prove more useful in defining the geometry of the propagation events, while the fabric, with its greater temporal resolution, is more useful for constraining the rate of propagation. It thus appears that joint inversion of magnetic and seafloor fabric data can be valuable in tectonic analyses.

  6. Continuous sea-floor spreading in Red Sea: an alternative interpretation of magnetic anomaly pattern

    SciTech Connect

    La Brecque, J.L.; Zitellini

    1985-04-01

    The magnetic anomaly pattern over the Red Sea can be modeled as a continuous system of sea-floor spreading from the early Miocene to the present by using a timevarying process filter. The half spreading rate is approximately 1 cm/yr (0.4 in./yr) since initial rifting. The parameters that determine the process filter and development of the transition zone are the intrusion parameter (a measure of the dispersion of feeder dikes or horizontal strain about the rift axis), a flow parameter (a measure of the average flow width), and the effusion parameter (a measure of the volcanic effusion and thickness of layer 2). The authors estimate the flow parameter to be 2.7km(1.7 mi) and the intrusion parameter to be 7.5km(4.7 mi) at early rifting. These values suggest that a wide distribution of axial dikes or horizontal strain is the dominant factor in forming the magnetic anomaly pattern. Reduction in the width of the intrusion parameter and the effusion rate as rifting proceeded resulted in focusing of the strain, thinning of layer 2, and formation of the Red Sea deeps. Their modeling suggests that phase 2, or the stratoid phase, began about the time of anomaly 5C or chron C5C approximately 16 Ma. This age is compatible with geologic estimates of the initial rifting at the late Oligocene to early Miocene (Coleman, 1974; Gass, 1977). The opening rate for Africa-Arabia plate motion has remained relatively constant since early rifting although the African margin appears to be accreting faster than the Arabian plate.

  7. Early India-Australia spreading history revealed by newly detected Mesozoic magnetic anomalies in the Perth Abyssal Plain

    NASA Astrophysics Data System (ADS)

    Williams, Simon E.; Whittaker, Joanne M.; Granot, Roi; Müller, Dietmar R.

    2013-07-01

    seafloor within the Perth Abyssal Plain (PAP), offshore Western Australia, is the only section of crust that directly records the early spreading history between India and Australia during the Mesozoic breakup of Gondwana. However, this early spreading has been poorly constrained due to an absence of data, including marine magnetic anomalies and data constraining the crustal nature of key tectonic features. Here, we present new magnetic anomaly data from the PAP that shows that the crust in the western part of the basin was part of the Indian Plate—the conjugate flank to the oceanic crust immediately offshore the Perth margin, Australia. We identify a sequence of M2 and older anomalies in the west PAP within crust that initially moved with the Indian Plate, formed at intermediate half-spreading rates (35 mm/yr) consistent with the conjugate sequence on the Australian Plate. More speculatively, we reinterpret the youngest anomalies in the east PAP, finding that the M0-age crust initially formed on the Indian Plate was transferred to the Australian Plate by a westward jump or propagation of the spreading ridge shortly after M0 time. Samples dredged from the Gulden Draak and Batavia Knolls (at the western edge of the PAP) reveal that these bathymetric features are continental fragments rather than igneous plateaus related to Broken Ridge. These microcontinents rifted away from Australia with Greater India during initial breakup at ~130 Ma, then rifted from India following the cessation of spreading in the PAP (~101-103 Ma).

  8. Magnetic anomalies and seafloor spreading rates in the northern South Atlantic.

    PubMed

    van Andel, T H; Moore, T C

    1970-04-25

    A geomagnetic profile across the northern South Atlantic yields spreading rates for the last 70 m.y. which vary from 1.6 to 2.0 cm/year. There is evidence for three regional discontinuities in the spreading history of the South Atlantic. PMID:16057239

  9. Opening of the Gulf of Mexico and the Nature of the Crust in the Deep Gulf: New Evidence from Seafloor Spreading Magnetic Anomalies

    NASA Astrophysics Data System (ADS)

    Harry, D. L.; Eskamani, P. K.

    2013-12-01

    The seafloor spreading history in the Gulf of Mexico is poorly constrained due to a lack of recognized seafloor spreading magnetic anomalies, a paucity of deep penetrating seismic data, and absence of drilling to constrain crystalline ocean floor composition and ages. We have identified lineated magnetic anomalies in the eastern Gulf on profiles collected during the Woods Hole R/V Farnella FRNL85-2 cruise that correlate with magnetic chrons M21R to M10. Forward modeling shows that these anomalies formed during creation of weakly magnetized new seafloor in the eastern Gulf between 149-134 Ma at an average half-spreading rate of 3.2 cm/yr. The oldest anomalies are located against stretched continental crust beneath the western Florida shelf on the east and the Yucatan shelf on the west. The youngest anomalies form a juxtaposed conjugate pair that mark the location of an extinct spreading ridge between Yucatan and Florida. Seismic velocities of the crust in the eastern Gulf and the amplitude of the magnetic anomalies are similar to the Iberian and Newfoundland rifted margins, where the early stages of continental breakup were accommodated by exhumation of subcontinental lithosphere rather than creation of new basaltic oceanic crust. We infer that the eastern Gulf of Mexico is underlain by exhumed sub-continental peridotitic mantle intruded by lesser volumes of basaltic igneous rocks generated by decompression melting of the asthenosphere during the late stages of opening of the Gulf. The long wavelength characteristics of the magnetic and gravity fields in the eastern Gulf, as well as the seismic velocity structure of the crust, differ from those in the central and western Gulf, which are more similar to typical magmatic rifted margins. This suggests that the character of the Gulf changes along strike, from a magmatic western portion to an amagmatic eastern portion. Paleogeographic restoration of the lineated magnetic anomaly pattern suggests a 4-phase model for opening of the Gulf. During phase 1 (Early Permian-Late Triassic), Yucatan and associated tectonic blocks that now comprise eastern Mexico were translated eastward from the Pacific realm into positions near the modern western Gulf. During phase 2 (Late Triassic-ca. 160 Ma) Yucatan and the South Florida block were translated southeastward relative to North America, rotating 6.7○ counterclockwise about a pole located at 34○N, 74○W. This resulted in ca. 430 km of southeastward extension on the North American coastal plain, 120 km of southward extension on the northern Yucatan shelf, and displacement of the South Florida Block from a pre-rift position on the northwest Florida shelf to its modern position. During phase 3 (ca. 160-149 Ma), Yucatan rotated counterclockwise 46○ relative to North America about a pole located at 27.6○N, 84.0○W. Phase 3 may have coincided with seafloor spreading in the central and western Gulf, but predated seafloor spreading in the eastern Gulf. During phase 4 (149-134 Ma), Yucatan moved southwestward relative to North America, rotating counterclockwise 2.2○ about a pole located at 17.6○N, 74.2○W and completing opening of the Gulf.

  10. Pacific plate apparent polar wander between 67 Ma and 44 Ma determined from the analysis of the skewness of both vector and scalar magnetic anomalies due to seafloor spreading

    NASA Astrophysics Data System (ADS)

    Zheng, L.; Gordon, R. G.; Horner-Johnson, B. C.

    2011-12-01

    Pacific plate apparent polar wander between 67 Ma and 44 Ma determined from the analysis of the skewness of both vector and scalar magnetic anomalies due to seafloor spreading The apparent polar wander (APW) path for the Pacific plate is important to the study of Pacific plate motions and their relation to circum-Pacific tectonics. It can be used to discriminate between alternative plate motion circuits, determine the motion of Pacific hotspots relative to the paleomagnetic axis, and test the fixed hotspot hypothesis. The pioneering investigations of Jean Francheteau and his colleagues of Pacific plate APW through the analysis of magnetic anomalies over seamounts helped to demonstrate that the Pacific plate has had substantial northward motion relative to the spin axis since Cretaceous time. We also investigate the APW of the Pacific plate through analysis of magnetic anomalies. Instead of anomalies over seamounts, however, we investigate the skewness (asymmetry) of magnetic anomalies due to seafloor spreading. In prior work, skewness analysis of shipboard magnetic profiles has been used to determine Pacific paleomagnetic poles for chron 25r (57 Ma B.P.; Petronotis et al., 1994), chron 27r to 31n (62 to 69 Ma B.P.; Acton and Gordon, 1991) and chron 32n (72 Ma B.P.; Petronotis and Gordon, 1999). Recently, vector aeromagnetic data from low paleolatitudes, combined with shipboard profiles from low paleolatitudes, were used to determine a paleomagnetic pole with compact confidence limits for anomaly 12r (32 Ma B.P.; Horner-Johnson and Gordon, 2010). Here we use the low-paleolatitude shipboard- and vector aero-magnetic profiles to determine new paleomagnetic poles for the Pacific plate. A new feature of our analysis is a correction for the spreading-rate dependence of anomalous skewness (Koivisto et al. 2011). We estimate anomalous skewness as a function of spreading rate for each anomaly by creating many synthetic profiles using the model of Dyment and Arkani-Hamed (1995) and by experimentally determining the phase shift that causes the resulting synthetic magnetic anomaly to best match a profile produced from a "standard" model for anomalies due to seafloor spreading that assumes simple vertical reversal boundaries (Boswell et al., 2011). Thus, we solve for only two adjustable parameters, the latitude and the longitude of the paleomagnetic pole. We focus on preliminary results from the skewness of crossings of magnetic anomalies 20r (44 Ma B.P.), 24r (55 Ma B.P.) and 30n/31n (67 Ma B.P.) between the Galapagos and Murray fracture zones on the Pacific plate. We choose this region of the Pacific plate because numerical experiments, similar to those conducted by Acton and Gordon (1991), show that these data contribute much more information about the location of paleomagnetic poles than do those from any other region of similar size. Implications for Pacific plate tectonics, motion between hotspots, and true polar wander will be discussed.

  11. Implications for the South Atlantic early breakup and seafloor spreading from joint interpretation of magnetic anomaly maps and seaward-dipping reflector sequences (SDRS) visible in conjugated reflection seismic sections

    NASA Astrophysics Data System (ADS)

    Schreckenberger, Bernd; Koopmann, Hannes; Franke, Dieter; Schnabel, Michael

    2013-04-01

    The late history of the South Atlantic passive margin evolution is investigated in the view of interlaced magnetic anomalies related to seafloor spreading lineations and anomalies caused by seaward-dipping reflector sequences (SDRS). Our identification of previously unknown pre-M5n lineations in marine magnetic data offshore Argentina now makes the lineation pattern more complete and most importantly comparable and nearly symmetrical to the conjugated area offshore South Africa. Therefore, we can now compare several sets of published South Atlantic reconstruction poles to our new pre-M5n lineations off Argentina and their equivalents off South Africa. The analysis of the symmetry of SDRS and particularly of their along-margin extension further constrains the choice of possible reconstruction poles for the earliest opening phases. The interpretation of pre-M5n lineations also defines the exact time (M9r) of the termination of excess breakup related volcanic activity and the transition to "normal" seafloor spreading. This is compared to absolute radiometric ages from Parana/Etendeka flood basalts. The volcanic activity related to the southernmost volcanic margin segments falls approximately into the same time window as the continental flood basalt activity. Unfortunately, more detailed conclusions suffer seriously from an ongoing discussion about the absolute ages of the pre-M0r lineations in different versions of polarity timescales. New models for the magnetic response of SDRS reveal a high variability within the wedges on either side of the Atlantic and between the conjugated margins. Former identifications of anomaly M11r off Cape Town have already been questioned and can now be shown to be caused by structural or magnetization variations within SDRS.

  12. Spreading rate dependence of gravity anomalies along oceanic transform faults.

    PubMed

    Gregg, Patricia M; Lin, Jian; Behn, Mark D; Montési, Laurent G J

    2007-07-12

    Mid-ocean ridge morphology and crustal accretion are known to depend on the spreading rate of the ridge. Slow-spreading mid-ocean-ridge segments exhibit significant crustal thinning towards transform and non-transform offsets, which is thought to arise from a three-dimensional process of buoyant mantle upwelling and melt migration focused beneath the centres of ridge segments. In contrast, fast-spreading mid-ocean ridges are characterized by smaller, segment-scale variations in crustal thickness, which reflect more uniform mantle upwelling beneath the ridge axis. Here we present a systematic study of the residual mantle Bouguer gravity anomaly of 19 oceanic transform faults that reveals a strong correlation between gravity signature and spreading rate. Previous studies have shown that slow-slipping transform faults are marked by more positive gravity anomalies than their adjacent ridge segments, but our analysis reveals that intermediate and fast-slipping transform faults exhibit more negative gravity anomalies than their adjacent ridge segments. This finding indicates that there is a mass deficit at intermediate- and fast-slipping transform faults, which could reflect increased rock porosity, serpentinization of mantle peridotite, and/or crustal thickening. The most negative anomalies correspond to topographic highs flanking the transform faults, rather than to transform troughs (where deformation is probably focused and porosity and alteration are expected to be greatest), indicating that crustal thickening could be an important contributor to the negative gravity anomalies observed. This finding in turn suggests that three-dimensional magma accretion may occur near intermediate- and fast-slipping transform faults. PMID:17625563

  13. Magnetic Anomaly Lineations in the Gulf of Aden

    NASA Astrophysics Data System (ADS)

    Noguchi, Y.; Nakanishi, M.; Tamaki, K.; Fujimoto, H.; Huchon, P.; Leroy, S. D.; Styles, P.

    2014-12-01

    We present the magnetic anomaly lineations in the Gulf of Aden. The Gulf of Aden has slow spreading ridges between the Arabia Plate and Somalia Plate. The Arabian plate moves away from Somalia Plate in an NE direction, at a rate of about 2 cm/yr. Previous works indicates that seafloor spreading started about 20 Ma in the eastern part of the Gulf of Aden and propagated westward. The spreading axis has a E-W trend west of 46 E and that east of 46 E has a N60 W trend. We examined magnetic data acquired in the cruises by R/V L'Atalante in 1995, R/V Hakuho-maru from 2000 to 2001, R/V Maurice Ewing in 2001, and Shackleton in 1975 and 1979. We also used data obtained from National Geophysical Data Center, NOAA. We calculated magnetic anomalies using the latest Internation Geomagnetic Reference Field. Elongated negative magnetic anomalies, which amplitude are more than 500 nT, observed over the spreading centers. Most of the elongated anomalies are parallel with the spreading centers. The elongated magnetic anomalies west of 46 30'E have an E-W trend around the spreading centers. Several discontinuities in the magnetic anomaly contour map illustrate the position of the fracture zones concealed by sediments. We identified magnetic lineations from 43 E to 52 E. Most of magnetic lineations west and east of 46 30'E have N-E and N60-65 W strikes, respectively. The oldest lineations are C3r (5.48~5.74 Ma) between 43 10'E and 44 E and C5Ar (12.4~12.7 Ma) east of 44 E. Our identification of magnetic anomaly lineations indicates a symmetric seafloor spreading with a spreading rate of about 1.0 cm/yr, although Leroy et al. (2004) showed an asymmetric seafloor spreading of the Sheba Ridge, east of our study area. The kinematics of the Arabia plate changed about 5 Ma, but our results did not show any coeval change in spreading rates of the spreading system in the Gulf of Aden.

  14. Interpretation of magnetic anomalies over the Grenada Basin

    NASA Astrophysics Data System (ADS)

    Bird, Dale E.; Hall, Stuart A.; Casey, John F.; Millegan, Patrick S.

    1993-10-01

    The Grenada Basin is a back arc basin located near the eastern border of the Caribbean Plate. The basin is bounded on the west by the north-south trending Aves Ridge (a remnant island arc) and on the east by the active Lesser Antilles island arc. Although this physiography suggests that east-west extension formed the basin, magnetic anomalies over the basin exhibit predominantly east-west trends. If the observed magnetic anomalies over the basin are produced by seafloor spreading, then the orientation of extension is complex. Extension in back arc basins is roughly normal to the trench, although some basins exhibit oblique extension. Present models for the formation of the Grenada Basin vary from north-south extension through northeast-southwest extension to east-west extension. An interpretation of magnetic anomalies over the Grenada Basin supports basin development by nearly east-west extension. Low amplitude magnetic anomaly trends subparallel to the island arc magnetic anomaly trends over the southern part of the basin and the results of forward three-dimensional (3-D) magnetic modeling are consistent with this conclusion. Late Cenozoic tectonic movements may have been responsible for disrupting the magnetic signature over the northern part of the basin. On the basis of our 3-D analysis, we attribute the prominent east-west trending anomalies of the Grenada Basin to fracture zones formed during seafloor spreading at low latitude. This east-west trend is not interpreted as indicating north-south extension of the basin.

  15. Deep-Tow magnetics near 20°S on the East Pacific Rise: A study of short wavelength anomalies at a very fast spreading center

    NASA Astrophysics Data System (ADS)

    Perram, Laura Jean; MacDonald, Ken C.; Miller, Stephen P.

    1990-08-01

    Six Deep-Tow magnetic profiles across the axis of the East Pacific Rise [EPR] in two small areas between 19°25' and 20°10'S were collected during the 1983 Protea 1 cruise of the R/V Melville. These near-bottom profiles are of extremely high resolution allowing the interpretation of very short wavelength features. We have inverted the magnetic field data to determine the rock magnetization distribution near the axis of this ultrafast speading center (162 mm yr-1). The solutions reveal large amplitude (up to 35 A m-1) short wavelength (1 3 km) variations in magnetization. Specifically all crossings show a narrow (0.5 to 1.5 km) low in magnetization superimposed on a broader (2.5 to 4 km) high directly over the ridge axis. Four profiles in the northern area (19°25' to 19°33'S) also show symmetrical near-axis (within 4 km) lows which are remarkably continuous along strike. Explanations for the short-wavelength variations are discussed which fall into the following categories: (1) variations in the thickness of the magnetized layer, (2) variations in rock chemistry (e.g. alteration due to hydrothermal activity), and (3) paleofield intensity variations. None of the mechanisms discussed alone adequately explain the observed phenomena in the study area or on a world-wide scale. Further sampling and high resolution surveying will be required in order to accurately determine the relative importance of the mechanisms discussed.

  16. Satellite Magnetic Anomalies of Africa and Europe

    NASA Technical Reports Server (NTRS)

    Hinze, W. J.; Vonfrese, R. R. B. (Principal Investigator); Olivier, R.

    1984-01-01

    Preliminary MAGSAT scalar magnetic anomaly data of Africa, Europe, and adjacent marine areas were reduced to the pole assuming a constant inducing Earth's magnetic field of 60,000 nT. This process leads to a consistent anomaly data set free from marked variations in directional and intensity effects of the Earth's magnetic field over this extensive region. The resulting data are correlated with long wave length-pass filtered free-air gravity anomalies; regional heat flow, and tectonic data to investigate magatectonic elements and the region's geologic history. Magnetic anomalies are related to both ancient as well as more recent Cenozoic structural features.

  17. Northern east Pacific rise: Magnetic anomaly and bathymetric framework

    SciTech Connect

    Klitgord, K.D.; Mammerickx, J.

    1982-08-10

    The oceanic crust in the eastern Pacific between 7/sup 0/N and 30/sup 0/N and east of 127/sup 0/W contains a fairly complete history of the spreading centers associated with the East Pacific Rise since 25 m.y. B.P. (late Oligocene). In this paper, we have summarized the seafloor spreading magnetic-anomaly data and the bathymetric data that reflect the record of this technique history. The well-defined magnetic lineations north of the Clarion fracture zone, in the mouth of the Gulf of California, and on the east flank of the East Pacific Rise (EPR) are carefully examined and used to provide a guide for interpreting the spreading pattern between the Clarion and Clipperton fracture zones, southward of the Rivera fracture zone over the Mathematician Ridge, and over the entire EPR east of the Mathematician Ridge between the Rivera and Siqueiros fracture zones. The bathymetric data provide a trace of the fracture zone pattern in each of the above mentioned areas. The fracture zone bathymetry and the seafloor spreading magnetc lineations on the EPR south of the Rivera fracture zone have a distinctive fanning pattern caused by close poles of rotation and plate boundary reorganizations. All these data provide a good record of the plate reorganizations in the middle Miocene at magnetic anomaly 5A time (12.5 to 11 m.y. B.P.), in the late Miocene at a magnetic anomaly 3'--4 time (6.5 m.y. B.P.), and in the Pliocene at magnetic anomaly 2'--3 time (3.5 m.y.B.P.). Several abandoned spreading centers, including the Mathematician Ridge, were left behind as a result of these reorganizations. The Mathematician Ridge is shown to be a set of ridges and trough whose origin is related to the tectonics activity associated with each of the above mentioned reorganizations since anomaly 5A.

  18. Regional magnetic anomaly constraints on continental rifting

    NASA Technical Reports Server (NTRS)

    Vonfrese, R. R. B.; Hinze, W. J.; Olivier, R.; Bentley, C. R.

    1985-01-01

    Radially polarized MAGSAT anomalies of North and South America, Europe, Africa, India, Australia and Antarctica demonstrate remarkably detailed correlation of regional magnetic lithospheric sources across rifted margins when plotted on a reconstruction of Pangea. These major magnetic features apparently preserve their integrity until a superimposed metamorphoric event alters the magnitude and pattern of the anomalies. The longevity of continental scale magnetic anomalies contrasts markedly with that of regional gravity anomalies which tend to reflect predominantly isostatic adjustments associated with neo-tectonism. First observed as a result of NASA's magnetic satellite programs, these anomalies provide new and fundamental constraints on the geologic evolution and dynamics of the continents and oceans. Accordingly, satellite magnetic observations provide a further tool for investigating continental drift to compliment other lines of evidence in paleoclimatology, paleontology, paleomagnetism, and studies of the radiometric ages and geometric fit of the continents.

  19. The source of marine magnetic anomalies

    NASA Technical Reports Server (NTRS)

    Harrison, Christopher G. A.

    1987-01-01

    The Vine-Matthews hypothesis (1963) is examined. This hypothesis suggests that oceanic rocks become polarized in the direction of the magnetic field at the time of their formation, thus recording the polarity history of the earth's magnetic field. This produces the lineated magnetic anomalies on either side of the midoceanic ridge crests. The strength of these magnetic anomalies is studied to determine the strength of magnetization. Indirect determinations of the magnetization intensity of the oceanic crust and direct observations of the oceanic crust are compared. It is found that the average magnetization of a 6-km thick oceanic crust is 1.18 A/m.

  20. Magnetic and gravity anomalies in the Americas

    NASA Technical Reports Server (NTRS)

    Braile, L. W.; Hinze, W. J.; Vonfrese, R. R. B. (Principal Investigator)

    1981-01-01

    The cleaning and magnetic tape storage of spherical Earth processing programs are reported. These programs include: NVERTSM which inverts total or vector magnetic anomaly data on a distribution of point dipoles in spherical coordinates; SMFLD which utilizes output from NVERTSM to compute total or vector magnetic anomaly fields for a distribution of point dipoles in spherical coordinates; NVERTG; and GFLD. Abstracts are presented for papers dealing with the mapping and modeling of magnetic and gravity anomalies, and with the verification of crustal components in satellite data.

  1. The magnetic anomaly of the Ivreazone

    NASA Technical Reports Server (NTRS)

    Albert, G.

    1979-01-01

    A magnetic field survey was made in the Ivreazone in 1969/70. The results were: significant anomaly of the vertical intensity is found. It follows the basic main part of the Ivrea-Verbano zone and continues to the south. The width of the anomaly is about 10 km, the maximum measures about +800 gamma. The model interpretation shows that possibly the anomaly belongs to an amphibolitic body, which in connection with the Ivrea-body was found by deep seismic sounding. Therefore, the magnetic anomaly provides further evidence for the conception that the Ivrea-body has to be regarded as a chip of earthmantle material pushed upward by tectonic processes.

  2. Marine Magnetic Anomalies and the Reconstruction of the World

    NASA Technical Reports Server (NTRS)

    Heirtzler, James R.; Smith, David E. (Technical Monitor)

    2000-01-01

    Until the middle of the 20th century little was known about magnetic anomalies in the oceans. Then it was discovered that there are relatively large anomalies in most of the oceans and they were unrelated to any geological structure known at that time. In the early 1950's large anomalies had been found over the Mid-Atlantic Ridge, and linear anomalies over the eastern continental shelf of North America and, shortly after that, off the west coast. A survey of the ridge south of Iceland showed that the anomalies were linear, parallel to the ridge axis, and symmetrical about the axis. Using the theory that the anomalies were caused by geomagnetic field reversals and seafloor spreading it was possible to greatly extend the time scale of geomagnetic reversals, to determine the velocity of seafloor spreading and estimate the time of opening of the North Atlantic. Lamont had a world-wide collection of marine magnetic profiles. These were used, systematically, to determine the positions of most of the land masses of the world since the beginnings of the world's present oceans.

  3. Understanding Magnetic Anomalies and Their Significance.

    ERIC Educational Resources Information Center

    Shea, James H.

    1988-01-01

    Describes a laboratory exercise testing the Vine-Matthews-Morley hypothesis of plate tectonics. Includes 14 questions with explanations using graphs and charts. Provides a historical account of the current plate tectonic and magnetic anomaly theory. (MVL)

  4. Satellite elevation magnetic anomaly maps

    NASA Technical Reports Server (NTRS)

    Braile, L. W.; Hinze, W. J. (Principal Investigator)

    1982-01-01

    The problem of inverting 2 deg average MAGSAT scalar anomalies for the region 80 W, 60 E longitude and 40 S, 70 N latitude was attempted on the LARS computer; however, the effort was aborted due to insufficient allocation of CPU-time. This problem is currently being resubmitted and should be implemented shortly for quantitative comparison with free-air gravity anomaly, geothermal, and tectonic data.

  5. Regional magnetic anomaly constraints on continental breakup

    SciTech Connect

    von Frese, R.R.B.; Hinze, W.J.; Olivier, R.; Bentley, C.R.

    1986-01-01

    Continental lithosphere magnetic anomalies mapped by the Magsat satellite are related to tectonic features associated with regional compositional variations of the crust and upper mantle and crustal thickness and thermal perturbations. These continental-scale anomaly patterns when corrected for varying observation elevation and the global change in the direction and intensity of the geomagnetic field show remarkable correlation of regional lithospheric magnetic sources across rifted continental margins when plotted on a reconstruction of Pangea. Accordingly, these anomalies provide new and fundamental constraints on the geologic evolution and dynamics of the continents and oceans.

  6. The mineralogy of global magnetic anomalies

    NASA Technical Reports Server (NTRS)

    Haggerty, S. E. (Principal Investigator)

    1984-01-01

    Experimental and analytical data on magnetic mineralogy was provided as an aid to the interpretation of magnetic anomaly maps. An integrated program, ranging from the chemistry of materials from 100 or more km depth within the Earth, to an examination of the MAGSAT anomaly maps at about 400 km above the Earth's surface, was undertaken. Within this framework, a detailed picture of the pertinent mineralogical and magnetic relationships for the region of West Africa was provided. Efforts were directed toward: (1) examining the geochemistry, mineralogy, magnetic properties, and phases relations of magnetic oxides and metal alloys in rocks demonstrated to have originated in the lower crust of upper mantle, (2) examining the assumption that these rocks portray the nature of their source regions; and (3) examining the regional geology, tectonics, gravity field and the MAGSAT anomaly maps for West Africa.

  7. Magnetic Anomalies in the South of Corad Rise, the Southern Indian Ocean

    NASA Astrophysics Data System (ADS)

    Nogi, Y.; Ikehara, M.; Nakamura, Y.; Kameo, K.; Katsuki, K.; Kawamura, S.; Kita, S.

    2008-12-01

    Seafloor age estimated from magnetic anomalies in the Southern Indian Ocean are vital to understanding the fragmentation process of the Gondwana, but the seafloor age still remain less well-defined because of the sparse observations in this area. To understand the seafloor spreading history related to the Gondwana breakup, total intensity and vector geomagnetic field measurements as well as swath bathymetry mapping were conducted during the R/V Hakuho-maru cruise KH-07-4 Leg3 in the Southern Indian Ocean between Cape Town, South Africa, and off Lützow-Holm Bay, Antarctica. Magnetic anomaly data have been collected along WNW-ESE trending structures of unknown origin inferred from satellite gravity anomalies just to the south of Conrad Rise. We have also collected magnetic anomaly data along NNE-SSW trending lineaments from satellite gravity anomaly data between the south of the Conrad Rise and off Lützow-Holm Bay. Magnetic anomalies with amplitude of about 500 nT, originating from normal and reversed magnetization of oceanic crust, are detected along the WNW-ESE trending structures just to the south of Conrad Rise. These magnetic anomalies possibly belong to Mesozoic magnetic anomaly sequence and this shows the part of the oceanic crust just to the south of the Conrad Rise formed before the long Cretaceous normal polarity superchron although magnetic anomaly C34 has been identified just to the north of the Conrad Rise. Magnetic anomalies with amplitude of about 300 nT are also observed along the NNE-SSW trending lineaments between the south of the Conrad Rise and off Lützow-Holm Bay, and most likely indicate Mesozoic magnetic anomaly sequence. These suggest the extinct spreading axes in the south of Conrad Rise and complicated seafloor spreading history in this area.

  8. Continental magnetic anomaly constraints on continental reconstruction

    NASA Technical Reports Server (NTRS)

    Vonfrese, R. R. B.; Hinze, W. J.; Olivier, R.; Bentley, C. R.

    1985-01-01

    Crustal magnetic anomalies mapped by the MAGSAT satellite for North and South America, Europe, Africa, India, Australia and Antarctica and adjacent marine areas were adjusted to a common elevation of 400 km and differentially reduced to the radial pole of intensity 60,000 nT. These radially polarized anomalies are normalized for differential inclination, declination and intensity effects of the geomagnetic field, so that in principle they directly reflected the geometric and magnetic polarization attributes of sources which include regional petrologic variations of the crust and upper mantle, and crustal thickness and thermal perturbations. Continental anomalies demonstrate remarkably detailed correlation of regional magnetic sources across rifted margins when plotted on a reconstruction of Pangea. Accordingly, they suggest further fundamental constraints on the geologic evolution of the continents and their reconstructions.

  9. The magnetic signature of hydrothermal systems in slow spreading environments

    NASA Astrophysics Data System (ADS)

    Tivey, Maurice A.; Dyment, Jérôme

    Slow spreading mid-ocean ridges like the Mid-Atlantic Ridge host a remarkable diversity of hydrothermal systems including vent systems located on the neovolcanic axis, large axial volcanoes, in transform faults and nontransform offsets, and associated with low-angle detachment faults, now recognized as a major tectonic feature of slow spreading environments. Hydrothermal systems are hosted in various lithologies from basalt to serpentinized peridotite and exposed lower oceanic crust. The substantial variations of hydrothermal processes active in these environments have important implications for the magnetic structure of oceanic crust and upper mantle. Hydrothermal processes can both destroy the magnetic minerals in basalt, diabase, and gabbro and create magnetic minerals by serpentinization of ultramafic rocks and deposition of magnetic minerals. We report on the diversity of magnetic anomaly signatures over the vent systems at slow spreading ridges and show that the lateral scale of hydrothermal alteration is fundamentally a local phenomenon. This highly focused process leads to magnetic anomalies on the scale of individual vent fields, typically a few hundreds of meters or less in size. To detect such features, high-resolution, near-bottom magnetic surveys are required rather than sea surface surveys. High-resolution surveys are now more tractable with deep-towed systems, dynamically positioned ships, and with the recent development of autonomous underwater vehicles, which allow detailed mapping of the seafloor on a scale relevant to hydrothermal activity. By understanding these present-day active hydrothermal systems, we can explore for yet to be discovered buried deposits preserved off-axis, both to determine past history of hydrothermal activity and for resource assessment.

  10. CHAMP Magnetic Anomalies of the Antarctic Crust

    NASA Technical Reports Server (NTRS)

    Kim, Hyung Rae; Gaya-Pique, Luis R.; vonFrese, Ralph R. B.; Taylor, Patrick T.; Kim, Jeong Woo

    2003-01-01

    Regional magnetic signals of the crust are strongly masked by the core field and its secular variations components and hence difficult to isolate in the satellite measurements. In particular, the un-modeled effects of the strong auroral external fields and the complicated- behavior of the core field near the geomagnetic poles conspire to greatly reduce the crustal magnetic signal-to-noise ratio in the polar regions relative to the rest of the Earth. We can, however, use spectral correlation theory to filter the static lithospheric and core field components from the dynamic external field effects. To help isolate regional lithospheric from core field components, the correlations between CHAMP magnetic anomalies and the pseudo magnetic effects inferred from gravity-derived crustal thickness variations can also be exploited.. Employing these procedures, we processed the CHAMP magnetic observations for an improved magnetic anomaly map of the Antarctic crust. Relative to the much higher altitude Orsted and noisier Magsat observations, the CHAMP magnetic anomalies at 400 km altitude reveal new details on the effects of intracrustal magnetic features and crustal thickness variations of the Antarctic.

  11. Correction of Marine Magnetic Data to Make a Magnetic Anomaly Map for Shatsky Rise

    NASA Astrophysics Data System (ADS)

    Huang, Y.; Sager, W. W.

    2013-12-01

    Shatsky Rise oceanic plateau was formed near a triple junction during a period of geomagnetic reversals, so magnetic lineations formed at the spreading ridges are important observations reflecting on its tectonic history. Shatsky Rise covers a large area (4.8 x 105 km2) and magnetic data in the area are sparse and irregularly spaced, posing a challenge for defining the magnetic anomalies. Original trackline data contain both natural and artificial artifacts that hinder their effective use. In this study, shipborne magnetic data from 101 cruises over and around Shatsky Rise were examined for errors, corrected and gridded. The data set was collected over a period of 51 years, during which the International Geomagnetic Reference Field (IGRF) changed many times. So the first and main correction was to reduce the total magnetic field data to anomalies by subtracting the most recent International Geomagnetic Reference Field (IGRF11). To correct for regular patterns of external field variations, the anomalies were recalculated by the use of Comprehensive Model: phase 4 (CM4). Observation outliers, usually caused by instrumental and transcription errors, are identifiable due to their extremely large differences from the nearby points. Most of these outliers are excluded and for only a few was it possible to recover reasonable anomaly values. Noisy segments were identified and deleted through inspection by their disagreement with the draft magnetic anomaly map. Position offsets were tested to find corrections for navigation errors for several cruises with poor navigation. After cleaning each cruise data track-by-track, or even segment-by-segment, crossover analysis was implemented and line-leveling is used to correct for systematic offsets between track lines. Comparisons of magnetic anomaly maps before and after these corrections show an apparent improvement of the quality and consistency of the data set. The Hawaiian magnetic lineations, Japanese magnetic lineations, and the trace of the Pacific-Izanagi-Farallon triple junction are identifiable in the magnetic anomaly map. The distribution of magnetic anomalies around and within Shatsky rise shows that magnetic anomalies penetrate most of Shatsky Rise, documenting its history of formation near the spreading ridges.

  12. Geological reasons for change in intensity of linear magnetic anomalies of the Kursk magnetic anomaly

    NASA Technical Reports Server (NTRS)

    Zhavoronkin, I. A.; Kopayev, V. V.

    1985-01-01

    The geological reasons for fluctuations in the anomalous field intensity along the polar axes were examined. The Kursk magnetic anomaly is used as the basis for the study. A geological-geophysical section was constructed which used the results of the interpretation of gravimagnetic anomalies.

  13. Explanation of the nature of stripe magnetic anomalies without inversions

    NASA Astrophysics Data System (ADS)

    Melikhov, Vjacheslav; Lygin, Ivan; Sokolova, Tatiana

    2014-05-01

    Several scientists of different branches express doubts on the validity of the Earth's geomagnetic field inversions hypothesis [Vine F.J., Matthews D.H, 1963]. Presently a lot of information allows to link the appearance of stripe magnetic anomalies of both signs with the spreading fracture structure (horizontal segmentation of intrusions and sills, breaks in the strong crust, vertical movements of blocks), remagnetization near the borders of the blocks, hydrothermal activity. Non-inversion mechanism of origin of linear stripe magnetic anomalies in the oceans could be explained as follows. Ascending asthenospheric flows have been enrich with volatile components, become thinner, pressure on the walls of the lithospheric plates grows and part them. When it approaches the surface: - horizontal tensile pressure grows, - lithostatic pressure in the vertical column of rocks decreases, - crust strong upper layer flakes away and begins to move horizontally. It is important that thin magmatic and magnetic layers (further layers) of the newly formed strong upper crust move away from the ridge axis. The structure of such layers forms by horizontal stresses and so consist of the hills and depressions sequences or updiped and downdiped blocks heaped each other. This layer is the main source of the magnetic field and cannot be approximated by a horizontal homogeneous plate as it proved before. In the mid-ocean ridges (MOR) the folding periods of layer depend on its thickness and rigidity and horizontal velocity of spreading. The higher velocity - the longer periods of roughness are and contrary. Same pattern is observed for the stripe magnetic anomalies distribution. The magnetic field of the MOR forms there due to young lava flows which get thermoremanent magnetization according the current direction of geomagnetic field. Partial destruction of the relief, overlaying and creation of the new shapes occur when new magma penetrates the moved magnetic layer. The process entails partial flux reversal of rocks with the decrease of total magnetic field amplitude. The complicated magnetic field with alternating-sign linear anomalies appears. Taking into account limited vertical thickness of the oceanic magnetic layer, the false effect of negative magnetization would appear even with short shifts of the blocks. Conclusions. Theoretical calculations and analysis 'in situ' data prove that observation of magnetic anomalies of both signs in MOR areas are connected with fracturing tectonics, horizontal segmentation of sills, faults in the crust, vertical movements of blocks, self remagnetization near its margins. At the present time geological and geophysical facts lead to revision of some facts of tectonic theory and rejection of the old hypothesis connected with simplified ideas of the magnetic layer regularity and cyclical nature of magma flows. The main task of this work is to return scientists to the initial point of stripe magnetic anomalies discovery and general revision of the oceanic crust's structure without the limitations of Vine-Matthews-Morley hypothesis. Please fill in your abstract text.

  14. Equivalent magnetization over the World's Ocean and the World Digital Magnetic Anomaly Map

    NASA Astrophysics Data System (ADS)

    Dyment, Jerome; Choi, Yujin; Hamoudi, Mohamed; Thébault, Erwan; Quesnel, Yoann; Roest, Walter; Lesur, Vincent

    2014-05-01

    As a by-product of our recent work to build a candidate model over the oceans for the second version of the World Digital Magnetic Anomaly Map (WDMAM), we derived global distributions of the equivalent magnetization in oceanic domains. In a first step, we use classic point source forward modeling on a spherical Earth to build a forward model of the marine magnetic anomalies at sea-surface. We estimate magnetization vectors using the age map of the ocean floor, the relative plate motions, the apparent polar wander path for Africa, and a geomagnetic reversal time scale. We assume two possible magnetized source geometry, involving both a 1 km-thick layer bearing a 10 A/m magnetization either on a regular spherical shell with a constant, 5 km-deep, bathymetry (simple geometry) or following the topography of the oceanic basement as defined by the bathymetry and sedimentary thickness (realistic geometry). Adding a present-day geomagnetic field model allows the computation of our initial magnetic anomaly model. In a second step, we adjust this model to the existing marine magnetic anomaly data, in order to make it consistent with these data. To do so, we extract synthetic magnetic along the ship tracks for which real data are available and we compare quantitatively the measured and computed anomalies on 100, 200 or 400 km-long sliding windows (depending the spreading rate). Among the possible comparison criteria, we discard the maximal range - too dependent on local values - and the correlation and coherency - the geographical adjustment between model and data being not accurate enough - to favor the standard deviation around the mean value. The ratio between the standard deviations of data and model on each sliding window represent an estimate of the magnetization ratio causing the anomalies, which we interpolate to adjust the initial magnetic anomaly model to the data and therefore compute a final model to be included in our WDMAM candidate over the oceanic regions lacking data. The above ratio, after division by the magnetization of 10 A/m used in the model, represents an estimate of the equivalent magnetization under the considered magnetized source geometry. The resulting distributions of equivalent magnetization are further discussed in terms of mid-ocean ridges, presence of hotspots and oceanic plateaus, and the age of the oceanic lithosphere. Global marine magnetic data sets and models represent a useful tool to assess first order magnetic properties of the oceanic lithosphere.

  15. Magnetic anomalies northeast of Cape Adare, northern Victoria Land (Antarctica), and their relation to onshore structures

    USGS Publications Warehouse

    Damaske, D.; Läufer, A.L.; Goldmann, F.; Möller, H.-D.; Lisker, F.

    2007-01-01

    An aeromagnetic survey was flown over the offshore region northeast of Cape Adare and the magnetic anomalies compared to onshore structures between Pennell Coast and Tucker Glacier. The magnetic anomalies show two nearly orthogonal major trends. NNW-SSE trending anomalies northeast of Cape Adare represent seafloor spreading within the Adare Trough. A connection of these anomalies to the Northern Basin of the Ross Sea is not clear. Onshore faults are closely aligned to offshore anomalies. Main trends are NW-SE to NNW-SSE and NE-SW to NNESSW. NNW-SSE oriented dextral-transtensional to extensional faults parallel the Adare Peninsula and Adare Trough anomalies. NE-SW trending normal faults appear to segment the main Hallett volcanic bodies.

  16. Band Iron Formations and Satellite Magnetic Anomalies

    NASA Astrophysics Data System (ADS)

    Nazarova, K. A.; Wasilewski, P.

    2005-05-01

    Band Iron Formations (BIF) are mainly Precambrian (2.5-1.8 Ga) sedimentary deposits and are composed of alternating layers of iron rich material and silica (chert). Precambrian BIF mark growth in the level of free oxygen in the atmosphere and the ocean which happened about 2.2 Ga. Distribution of main BIF includes Hamersley Range, Australia; Transvaal-Griquatown, South Africa; Minas Gerais, Brazil; Labrador Trough, Canada, and Kursk-Krivoi Rog (Russia). Together these five very large BIF deposits constitute about 90 percent of Earth's total estimated BIF (5.76*10 14 ). On each continent these ancient rocks usually metamorphosed and crystallized include what are variously described as hematite-quartzites, banded iron formations, banded jaspers or calico-rocks. West African, Hudson Bay and Western Australian Satellite Magnetic Anomalies coincide with distribution BIF deposits. The Kursk Satellite Magnetic Anomaly (KMA) (about 22 nT at the altitude=400km, centered at 51o N, 37o E) also was identified by ground and aeromagnetic observations and is recognized as one of the largest magnetic anomaly on the Earth. Magnetic modeling shows that immense Precambrian iron ore deposits (iron bands) of Voronezh uplift are the main source of KMA. Magnetic properties of 10000 BIF samples outcropped in the KMA area have been measured and analyzed (Krutikhovskaya et al., 1964) Rockmag BIF dataset is presented at: http://core2.gsfc.nasa.gov/MPDB/datasets.html. Mean NRM value is about 42 A/M, Qn about 1.4. Demagnetization tests suggest that hard and stable NRM component is caused by hematite occurring in BIF in different forms and grain sizes. Hematite deposits discovered on Mars in western equatorial area with layered topography of Aram Chaos and Sinus Meridiani could be of hydrothermal origin and may be formed similar to hematite precipitated in BIF on Earth.

  17. Mesozoic Sequence Magnetic Anomalies in the South of Corad Rise, the Southern Indian Ocean

    NASA Astrophysics Data System (ADS)

    Nogi, Y.; Ikehara, M.; Nakamura, Y.; Kameo, K.; Katsuki, K.; Kawamura, S.; Kita, S.

    2009-04-01

    The Southern Indian Ocean is key area for understanding the fragmentation process of the Gondwana. However, tectonic history in the Southern Indian Ocean still remains less well-defined because of the sparse observations in this area. The R/V Hakuho-maru cruise KH-07-4 Leg3 were conducted to understand the tectonic history related to the Gondwana breakup in the Southern Indian Ocean between Cape Town, South Africa, and off Lutzow-Holm Bay, Antarctica. Total intensity and vector geomagnetic field measurements as well as swath bathymetry mapping were collected during the cruise. Magnetic anomaly data have been collected along WNW-ESE trending inferred from satellite gravity anomalies just to the south of Conrad Rise. We have also collected magnetic anomaly data along NNE-SSW trending lineaments from satellite gravity anomaly data between the south of the Conrad Rise and off Lutzow-Holm Bay. Magnetic anomalies with amplitude of about 500 nT, originating from normal and reversed magnetization of oceanic crust are detected along the WNW-ESE trending structures just to the south of Conrad Rise. Those magnetic anomalies most likely indicate Mesozoic magnetic anomaly sequence, Mesozoic sequence magnetic anomalies with amplitude of about 300 nT are also observed along the NNE-SSW trending lineaments between the south of the Conrad Rise and off Lutzow-Holm Bay. Oceanic crusts formed during Cretaceous normal polarity superchron are found in both profiles, although magnetic anomaly C34 has been identified just to the north of the Conrad Rise. These suggest the extinct spreading axes in the south of Conrad Rise and the two different seafloor spreading systems were active around Cretaceous normal polarity superchron between the south of the Conrad Rise and off Lutzow-Holm Bay. These provide new constraints for the fragmentation process of the Gondwana.

  18. Crustal Magnetic Field Anomalies and Global Tectonics

    NASA Astrophysics Data System (ADS)

    Storetvedt, Karsten

    2014-05-01

    A wide variety of evidence suggests that the ruling isochron (geomagnetic polarity versus age) hypothesis of marine magnetic lineations has no merit - undermining therefore one of the central tenets of plate tectonics. Instead, variable induction by the ambient geomagnetic field is likely to be the principal agent for mega-scale crustal magnetic features - in both oceanic and continental settings. This revitalizes the fault-controlled susceptibility-contrast model of marine magnetic lineations, originally proposed in the late 1960s. Thus, the marine magnetic 'striping' may be ascribed to tectonic shearing and related, but variable, disintegration of the original iron-oxide mineralogy, having developed primarily along one of the two pan-global sets of orthogonal fractures and faults. In this way, fault zones (having the more advanced mineral alteration) would be characterized by relatively low susceptibility, while more moderately affected crustal sections (located between principal fault zones) would be likely to have less altered oxide mineralogy and therefore higher magnetic susceptibility. On this basis, induction by the present geomagnetic field is likely to produce oscillating magnetic field anomalies with axis along the principal shear grain. The modus operandi of the alternative magneto-tectonic interpretation is inertia-driven wrenching of the global Alpine age palaeo-lithosphere - triggered by changes in Earth's rotation. Increasing sub-crustal loss to the upper mantle during the Upper Mesozoic had left the ensuing Alpine Earth in a tectonically unstable state. Thus, sub-crustal eclogitization and associated gravity-driven delamination to the upper mantle led to a certain degree of planetary acceleration which in turn gave rise to latitude-dependent, westward inertial wrenching of the global palaeo-lithosphere. During this process, 1) the thin and mechanically fragile oceanic crust were deformed into a new type of broad fold belts, and 2) the continents were subjected to relative 'in situ' rotations (mostly moderate). Examples of marine magnetic lineations with landward continuation along prominent transcurrent fault zones, and the fact that striped marine magnetic anomalies may display orthogonal networks - concordant with the ubiquitous system of rectilinear fractures, faults and joints - corroborate the wrench tectonic interpretation of crustal field anomalies.

  19. Paleo-Pole Positions from Martian Magnetic Anomaly Data

    NASA Technical Reports Server (NTRS)

    Taylor, Patrick T.; Frawley, James J.

    2003-01-01

    Magnetic component anomaly maps were made from five mapping cycles of the Mars Global Surveyor s magnetometer data. Our goal was to find and isolate positive and negative anomaly pairs which would indicate magnetization of a single source body. From these anomalies we could compute the direction of the magnetizing vector and subsequently the location of the magnetic pole existing at the time of magnetization. We found nine suitable anomaly pairs and from these we computed four North and 3 South poles with two at approximately 60 degrees north latitude. These results suggest that during the existence of the Martian main magnetic field it experienced several reversals.

  20. Paleo-Pole Positions from Martian Magnetic Anomaly Data

    NASA Technical Reports Server (NTRS)

    Frawley, James J.; Taylor, Patrick T.

    2004-01-01

    Magnetic component anomaly maps were made from five mapping cycles of the Mars Global Surveyor's magnetometer data. Our goal was to find and isolate positive and negative anomaly pairs which would indicate magnetization of a single source body. From these anomalies we could compute the direction of the magnetizing vector and subsequently the location of the magnetic pole existing at the time of magnetization. We found nine suitable anomaly pairs and from these we computed paleo-poles that were nearly equally divided between north, south and mid-latitudes. These results suggest that during the existence of the martian main magnetic field it experienced several reversals and excursions.

  1. Marine magnetic anomalies - The origin of the stripes

    NASA Technical Reports Server (NTRS)

    Harrison, C. G. A.

    1987-01-01

    The results of recent observational and theoretical investigations of lineated magnetic anomalies on the ocean floor are summarized in tables, graphs, and diagrams and analyzed. Topics addressed include early lineation models, inversions of magnetic anomalies to obtain source functions, deep-tow studies of magnetic anomalies, evidence from the long-wavelength component of the magnetic field (including Magsat observations), and direct measurements of the magnetic properties of oceanic rocks. It is concluded that the source of the lineated anomalies must reside in most of the oceanic crust, not just in the pillow lavas of layer 2A.

  2. A global magnetic anomaly map. [obtained from POGO satellite data

    NASA Technical Reports Server (NTRS)

    Regan, R. D.; Davis, W. M.; Cain, J. C.

    1974-01-01

    A subset of POGO satellite magnetometer data has been formed that is suitable for analysis of crustal magnetic anomalies. Using a thirteenth order field model, fit to these data, magnetic residuals have been calculated over the world to latitude limits of plus 50 deg. These residuals averaged over one degree latitude-longitude blocks represent a detailed global magnetic anomaly map derived solely from satellite data. Preliminary analysis of the map indicates that the anomalies are real and of geological origin.

  3. Indoor waypoint navigation via magnetic anomalies.

    PubMed

    Riehle, Timothy H; Anderson, Shane M; Lichter, Patrick A; Condon, John P; Sheikh, Suneel I; Hedin, Daniel S

    2011-01-01

    A wide assortment of technologies have been proposed to construct indoor navigation services for the blind and vision impaired. Proximity-based systems and multilateration systems have been successfully demonstrated and employed. Despite the technical success of these technologies, broad adoption has been limited due to their significant infrastructure and maintenance costs. An alternative approach utilizing the indoor magnetic signatures inherent to steel-frame buildings solves the infrastructure cost problem; in effect the existing building is the location system infrastructure. Although magnetic indoor navigation does not require the installation of dedicated hardware, the dedication of resources to produce precise survey maps of magnetic anomalies represents a further barrier to adoption. In the present work an alternative leader-follower form of waypoint-navigation system has been developed that works without surveyed magnetic maps of a site. Instead the wayfarer's magnetometer readings are compared to a pre-recorded magnetic "leader" trace containing magnetic data collected along a route and annotated with waypoint information. The goal of the navigation system is to correlate the follower's magnetometer data with the leader's to trigger audio cues at precise points along the route, thus providing location-based guidance to the user. The system should also provide early indications of off-route conditions. As part of the research effort a smartphone based application was created to record and annotate leader traces with audio and numeric data at waypoints of interest, and algorithms were developed to determine (1) when the follower reaches a waypoint and (2) when the follower goes off-route. A navigation system utilizing this technology would enable a low-cost indoor navigation system capable of replaying audio annotations at precise locations along pre-recorded routes. PMID:22255538

  4. The mineralogy of global magnetic anomalies

    NASA Technical Reports Server (NTRS)

    Haggerty, S. E. (Principal Investigator)

    1981-01-01

    Progress is reported in developing predictive abilities to evaluate the potential stabilities of magnetic minerals in the Earth crust and mantle by: (1) computing oxidation state profiling as a function of temperature and pressure; (2) compiling data on basalts to establish validity of the oxidation state profiles; (3) determining Fe-Ni alloys in association with magnetitie as a function of temperature and oxidation state; and (4) acquiring large chemical data banks on the mineral ilmenite which decomposes to mineral spinel in the presence of high sulfur or carbonate environments in the lower crust upper mantle. In addition to acquiring these data which are related to constraining Curie isotherm depths, an excellent correlation was found between MAGSAT anomaly data and the geology of West Africa.

  5. Continental and oceanic magnetic anomalies: Enhancement through GRM

    NASA Technical Reports Server (NTRS)

    Vonfrese, R. R. B.; Hinze, W. J.

    1985-01-01

    In contrast to the POGO and MAGSAT satellites, the Geopotential Research Mission (GRM) satellite system will orbit at a minimum elevation to provide significantly better resolved lithospheric magnetic anomalies for more detailed and improved geologic analysis. In addition, GRM will measure corresponding gravity anomalies to enhance our understanding of the gravity field for vast regions of the Earth which are largely inaccessible to more conventional surface mapping. Crustal studies will greatly benefit from the dual data sets as modeling has shown that lithospheric sources of long-wavelength magnetic anomalies frequently involve density variations which may produce detectable gravity anomalies at satellite elevations. Furthermore, GRM will provide an important replication of lithospheric magnetic anomalies as an aid to identifying and extracting these anomalies from satellite magnetic measurements. The potential benefits to the study of the origin and characterization of the continents and oceans, that may result from the increased GRM resolution are examined.

  6. Remote energetic neutral atom imaging of electric potential over a lunar magnetic anomaly

    NASA Astrophysics Data System (ADS)

    Futaana, Y.; Barabash, S.; Wieser, M.; Lue, C.; Wurz, P.; Vorburger, A.; Bhardwaj, A.; Asamura, K.

    2013-01-01

    Abstract<p label="1">The formation of electric potential over lunar <span class="hlt">magnetized</span> regions is essential for understanding fundamental lunar science, for understanding the lunar environment, and for planning human exploration on the Moon. A large positive electric potential was predicted and detected from single point measurements. Here, we demonstrate a remote imaging technique of electric potential mapping at the lunar surface, making use of a new concept involving hydrogen neutral atoms derived from solar wind. We apply the technique to a lunar <span class="hlt">magnetized</span> region using an existing dataset of the neutral atom energy spectrometer SARA/CENA on Chandrayaan-1. Electrostatic potential larger than +135 V inside the Gerasimovic <span class="hlt">anomaly</span> is confirmed. This structure is found <span class="hlt">spreading</span> all over the <span class="hlt">magnetized</span> region. The widely <span class="hlt">spread</span> electric potential can influence the local plasma and dust environment near the <span class="hlt">magnetic</span> <span class="hlt">anomaly</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19850023272','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19850023272"><span id="translatedtitle">Improving the geological interpretation of <span class="hlt">magnetic</span> and gravity satellite <span class="hlt">anomalies</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hinze, W. J.; Braile, L. W. (Principal Investigator); Vonfrese, R. R. B.</p> <p>1985-01-01</p> <p>Current limitations in the quantitative interpretation of satellite-elevation geopotential field data and <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> data were investigated along with techniques to overcome them. A major result was the preparation of an improved scalar <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> map of South America and adjacent marine areas directly from the original MAGSAT data. In addition, comparisons of South American and Euro-African data show a strong correlation of <span class="hlt">anomalies</span> along the Atlantic rifted margins of the continents.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19880029596&hterms=seafloor+spreading&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3D%2528seafloor%2Bspreading%2529','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19880029596&hterms=seafloor+spreading&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3D%2528seafloor%2Bspreading%2529"><span id="translatedtitle">A model of ocean basin crustal <span class="hlt">magnetization</span> appropriate for satellite elevation <span class="hlt">anomalies</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Thomas, Herman H.</p> <p>1987-01-01</p> <p>A model of ocean basin crustal <span class="hlt">magnetization</span> measured at satellite altitudes is developed which will serve both as background to which anomalous <span class="hlt">magnetizations</span> can be contrasted and as a beginning point for studies of tectonic modification of normal ocean crust. The model is based on published data concerned with the petrology and <span class="hlt">magnetization</span> of the ocean crust and consists of viscous <span class="hlt">magnetization</span> and induced <span class="hlt">magnetization</span> estimated for individual crustal layers. Thermal remanent <span class="hlt">magnetization</span> and chemical remanent <span class="hlt">magnetization</span> are excluded from the model because seafloor <span class="hlt">spreading</span> <span class="hlt">anomalies</span> are too short in wavelength to be resolved at satellite altitudes. The exception to this generalization is found at the oceanic <span class="hlt">magnetic</span> quiet zones where thermal remanent <span class="hlt">magnetization</span> and chemical remanent <span class="hlt">magnetization</span> must be considered along with viscous <span class="hlt">magnetization</span> and induced <span class="hlt">magnetization</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012epsc.conf..408K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012epsc.conf..408K"><span id="translatedtitle">Influence of Impact Ejecta on Crustal <span class="hlt">Magnetic</span> Field <span class="hlt">Anomalies</span>.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kuzmicheva, M.; Losseva, T.</p> <p>2012-09-01</p> <p>A role of impact ejecta and post-impact atmospheric plume in providing <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> is considered. It is shown that impact-ejecta generated <span class="hlt">magnetic</span> field can provide both positive and negative <span class="hlt">anomalies</span>. Geomagnetic field disturbances detected after the Tunguska bolide explosion are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1985Tectp.113..233B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1985Tectp.113..233B"><span id="translatedtitle">Negative gravity <span class="hlt">anomaly</span> over <span class="hlt">spreading</span> rift valleys: Mid-Atlantic Ridge at 26°N</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bowin, Carl; Milligan, Julie</p> <p>1985-03-01</p> <p>A pronounced negative free-air gravity <span class="hlt">anomaly</span> commonly occurs over the median valley of slow <span class="hlt">spreading</span> ocean ridges. Previous results, using Wiener filtering and cross-spectral analysis techniques for the Mid-Atlantic Ridge, obtained estimates of the elastic plate thickness in the range of 7-13 km and the existence of a residual negative gravity <span class="hlt">anomaly</span> over the median rift valley, suggesting that the rift valley has a response function different than the remainder of the <span class="hlt">spreading</span> ridge. In this paper we have improved the derivation of the topography-gravity admittance function for <span class="hlt">spreading</span> ocean crust by carefully avoiding several sources of spectral splattering when processing the data: (1) selecting data from a cruise that followed a flowline of central North Atlantic relative plate motion and hence is least corrupted by fracture zones; and (2) accounting for the difference in distance between the gravity meter and the regional variation in elevation as the ridge crest is traversed. Improvements of lesser importance include the use of cubic splines to interpolate to equally spaced data rather than linear interpolation, and correction of the free-air <span class="hlt">anomaly</span> values for long-wavelength variations of the indirect effect. Comparison of the resulting admittance function to elastic flexure response functions suggests an elastic plate thickness of about 8 km. The improved admittance function, when convolved with the ridge topography, provides a predicted gravity profile that accounts very well for the negative <span class="hlt">anomaly</span> over the rift valley. Therefore, the isostatic response function for the rift valley is similar to that for the topography away from the rift valley.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/7064270','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/7064270"><span id="translatedtitle"><span class="hlt">Magnetic</span> <span class="hlt">anomalies</span> and tectonic fabric of marginal basins North of New Zealand</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Malahoff, A.; Feden, R.H.; Fleming, H.S.</p> <p>1982-05-10</p> <p>Detailed airborne <span class="hlt">magnetic</span> studies conducted over the region of the S. W. Pacific marginal basins extending from the Solomon Islands to New Zealand suggest that three major phases of basin formation and island arc development have occurred in this region. Development of the Tasman Sea took place during the Late Cretaceous-Paleocene. Development of the basins to the east of the Tasman Sea occurred predominantly during the Oligocene as well as during the Upper Miocene to Recent. The South Fuji Basin, consisting of the Kupe and Minerva Abyssal Plains, is marked by the presence of possibly two RRR triple junction <span class="hlt">spreading</span> centers that were active between the times of <span class="hlt">anomalies</span> 13 to 7 (36--25.5 m.y.). The Kupe Abyssal Plain shows the presence of residual <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> 7 to 13 of the eastern limb of the proposed <span class="hlt">spreading</span> center. The western limb appears to have been subducted beneath the present site of the Three Kings Rise. This seafloor <span class="hlt">spreading</span> phase (calculated half-<span class="hlt">spreading</span> rate of 35 mm/yr) was coincident with the overthrusting phase of the New Caledonia ultramafic rocks. During that period, active volcanism along the then continuous Solomons-New Hebrides-Fiji-Lau Island arc was taking place. <span class="hlt">Magnetic</span> <span class="hlt">anomalies</span> from 1 to 4 (0--8 m.y. B. P.) are seen to extend along a clearly defined lineation pattern over the North Fuji Basin.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003EAEJA.....7996H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003EAEJA.....7996H"><span id="translatedtitle"><span class="hlt">Magnetic</span> satellite <span class="hlt">anomalies</span> and tectonostratigraphic terranes over Mexico</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hernández-Quintero, E.; Campos-Enríquez, O.</p> <p>2003-04-01</p> <p>Satellite <span class="hlt">magnetic</span> data from Magsat are described and correlated with surface or near surface <span class="hlt">magnetic</span> studies between 10° and 35° north latitude and 85° and 120° west longitude. Mexico is featured by six satellite regional <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>. Based in such results we made a detailed description of these <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> (geographic extension, intensity, polarity). In order to approach our goal, filtering and enhancement of <span class="hlt">magnetic</span> features were made (i.e., reduction to the pole, first and second vertical derivatives) resulting some maps where such features appear more clear. A first attempt to correlate these data with other studies such as gravimetry, geology, seismicity, heat flow, available in Mexico were developed in order to have a more basis to infer their origin. We found in some areas a high correlation between tectonostratigraphic Mexican terranes and <span class="hlt">magnetic</span> satellite <span class="hlt">anomalies</span>. According to our study there is evidence of <span class="hlt">magnetic</span> material in the crust along the Gulf of Mexico coast plains with a degree of correlation with north Mayan terrane. Trans-Mexican Volcanic Belt (MVB) is divided in a more <span class="hlt">magnetic</span> area to the east with a thick crust and low heat flow, meanwhile the west part is less <span class="hlt">magnetic</span> with a thinner crust and high heat flow. Cochimi (ultramafic), Pericu and Yuma terranes are correlated with a <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> to the south of Baja California peninsula. <span class="hlt">Magnetic</span> <span class="hlt">anomaly</span> observed in the Gulf of Mexico is well correlated with oceanic crust. Maya terrane is composed by <span class="hlt">magnetic</span> crust. Likewise Mohave-Sonora Megashear seems to be southern limit of an <span class="hlt">anomaly</span> located in the west part of Texas. The South of the studied area points that Mixteco, Zapoteco and Cuicateco terranes are underlied with <span class="hlt">magnetic</span> material. <span class="hlt">Anomalies</span> in Baja California peninsula and Middle America Trench, could be associated with pieces of the extinct oceanic Farallon plate. Our results seem to correlate with the existence of Oaxaquia terrane. Finally we present preliminary interpretation of three profiles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19850003130','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19850003130"><span id="translatedtitle">The south-central United States <span class="hlt">magnetic</span> <span class="hlt">anomaly</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hinze, W. J.; Braile, L. W. (Principal Investigator); Starich, P. J.</p> <p>1984-01-01</p> <p>The South-Central United States <span class="hlt">Magnetic</span> <span class="hlt">Anomaly</span> is the most prominent positive feature in the MAGSAT scalar <span class="hlt">magnetic</span> field over North America. The <span class="hlt">anomaly</span> correlates with increased crustal thickness, above average crustal velocity, negative free air gravity <span class="hlt">anomalies</span> and an extensive zone of Middle Proterozoic anorogenic felsic basement rocks. Spherical dipole source inversion of the MAGSAT scalar data and subsequent calculation of reduced to pole and derivative maps provide constraints for a crustal <span class="hlt">magnetic</span> model which corresponds geographically to the extensive Middle Proterozoic felsic rocks trending northeasterly across the United States. These felsic rocks contain insufficient <span class="hlt">magnetization</span> or volume to produce the <span class="hlt">anomaly</span>, but are rather indicative of a crustal zone which was disturbed during a Middle Proterozoic thermal event which enriched <span class="hlt">magnetic</span> material deep in the crust.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19820014754','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19820014754"><span id="translatedtitle">Study of gravity and <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> using MAGSAT data</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Braile, L. W.; Hinze, W. J.; Vonfrese, R. R. B. (Principal Investigator)</p> <p>1981-01-01</p> <p>The results of modeling satellite-elevation <span class="hlt">magnetic</span> and gravity data using the constraints imposed by near surface data and seismic evidence shows that the <span class="hlt">magnetic</span> minimum can be accounted for by either an intracrustal lithologic variation or by an upwarp of the Curie point isotherm. The long wavelength <span class="hlt">anomalies</span> of the NOO's-vector <span class="hlt">magnetic</span> survey of the conterminous U.S. were contoured and processed by various frequency filters to enhance particular characteristics. A preliminary inversion of the data was completed and the <span class="hlt">anomaly</span> field calculated at 450 km from the equivalent <span class="hlt">magnet</span> sources to compare with the POGO satellite data. Considerable progress was made in studing the satellite <span class="hlt">magnetic</span> data of South America and adjacent marine areas. Preliminary versions of the 1 deg free-air gravity <span class="hlt">anomaly</span> map (20 m gal contour interval) and the high cut (lambda approximately 8 deg) filtered <span class="hlt">anomaly</span> maps are included.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JESS..125..359S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JESS..125..359S"><span id="translatedtitle"><span class="hlt">Magnetic</span> <span class="hlt">anomalies</span> over the Andaman Islands and their geological significance</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Subba Rao, P. B. V.; Radhakrishna, M.; Haripriya, K.; Rao, B. Someswara; Chandrasekharam, D.</p> <p>2016-03-01</p> <p>The Andaman Islands form part of the outer-arc accretionary sedimentary complex belonging to the Andaman-Sumatra active subduction zone. The islands are characterized by thick cover of Neogene sediments along with exposed ophiolite rocks at few places. A regional <span class="hlt">magnetic</span> survey was carried out for the first time over the Andaman Islands with a view to understand the correlation of <span class="hlt">anomaly</span> signatures with surface geology of the islands. The residual total field <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> maps have revealed distinct <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> having intermediate to high amplitude <span class="hlt">magnetic</span> signatures and correlate with the areas over/close to the exposed ophiolite rocks along the east coast of north, middle and the south Andaman Islands. The 2D modelling of <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> along selected E-W profiles across the islands indicate that the ophiolite bodies extend to a depth of about 5-8 km and spatially correlate with the mapped fault/thrust zones.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19850023279&hterms=magnetic+field+air&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dmagnetic%2Bfield%2Bof%2Bair','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19850023279&hterms=magnetic+field+air&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dmagnetic%2Bfield%2Bof%2Bair"><span id="translatedtitle">The south-central United States <span class="hlt">magnetic</span> <span class="hlt">anomaly</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Starich, P. J.</p> <p>1985-01-01</p> <p>The South-Central United States <span class="hlt">Magnetic</span> <span class="hlt">Anomaly</span> is the most prominent positive feature in the MAGSAT scalar <span class="hlt">magnetic</span> field over North America. The <span class="hlt">anomaly</span> correlates with increased crustal thickness, above average crustal velocity, negative free-air gravity <span class="hlt">anomalies</span> and an extensive zone of Middle Proterozoic anorogenic felsic basement rocks. Spherical dipole source inversion of the MAGSAT scalar data and subsequent calculation of reduced-to-pole and derivative maps provide additional constraints for a crustal <span class="hlt">magnetic</span> model which corresponds geographically to the extensive Middle Proterozoic felsic rocks trending northeasterly across the United States. These felsic rocks contain insufficient <span class="hlt">magnetization</span> or volume to produce the <span class="hlt">anomaly</span>, but are rather indicative of a crustal zone which was disturbed during a Middle Proterozoic thermal event which enriched <span class="hlt">magnetic</span> material deep in the crust.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5545714','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5545714"><span id="translatedtitle">Alternative explanation for intermediate--wavelength <span class="hlt">magnetic</span> <span class="hlt">anomalies</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Shure, L.; Parker, R.L.</p> <p>1981-12-10</p> <p>Harrison and Carle and others have examined very long profiles of the <span class="hlt">magnetic</span> field and have calculated one-dimensional power spectra. In these they expect to see, but do not find, a minimum in power at intermediate wavelengths, between 65 and 150 km. Conventional one-dimensional models of the field predict very little power in this band, which lies between the spectral peaks arising from sources in the crust and the core. Mantle sources or high-intensity, long-wavelength <span class="hlt">magnetizations</span> have been proposed to account for the observations. An alternative, more plausible explanation is that one-dimensional spectra of two-dimensional fields contain contributions from wavenumbers in the perpendicular (i.e., nonsampled) direction. Unless the seafloor <span class="hlt">spreading</span> <span class="hlt">anomalies</span> are perfectly lineated at right angles to the profile, some low-wavenumber energy must be attributed to this effect; we propose that such directional aliasing is a major factor in the power spectra. To support this idea we discuss theoretical models and analyze a large-scale marine survey.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19990102924','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19990102924"><span id="translatedtitle">Hematite Versus Magnetite as the Signature for Planetary <span class="hlt">Magnetic</span> <span class="hlt">Anomalies</span>?</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kletetshka, Gunther; Taylor, Patrick T.; Wasilewski, Peter J.</p> <p>1999-01-01</p> <p>Crustal <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> are the result of adjacent geologic units having contrasting <span class="hlt">magnetization</span>. This <span class="hlt">magnetization</span> arises from induction and/or remanence. In a planetary context we now know that Mars has significant crustal <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> due to remanent <span class="hlt">magnetization</span>, while the Earth has some <span class="hlt">anomalies</span> where remanence can be shown to be important. This picture, however, is less clear because of the nature and the magnitude of the geomagnetic field which is responsible for superimposed induced <span class="hlt">magnetization</span>. Induced <span class="hlt">magnetization</span> assumes a magnetite source, because of its much greater <span class="hlt">magnetic</span> susceptibility when compared with other <span class="hlt">magnetic</span> minerals. We investigated the TRM (thermoremanent <span class="hlt">magnetization</span>) acquisition of hematite, in weak <span class="hlt">magnetic</span> fields up to 1 mT, to determine if the remanent and induced <span class="hlt">magnetization</span> of hematite could compete with magnetite. TRM acquisition curves of magnetite and hematite show that multi-domain hematite reaches TRM saturation (0.3 - 0.4 A sq m/kg) in fields as low as 100 microT. However, multi-domain magnetite reaches only a few percent of its TRM saturation in a field of 100 microT (0.02 - 0.06 A sq m/kg). These results suggest that a mineral such as hematite and, perhaps, other minerals with significant remanence and minor induced <span class="hlt">magnetization</span> may play an important role in providing requisite <span class="hlt">magnetization</span> contrast. Perhaps, and especially for the Mars case, we should reevaluate where hematite and other minerals, with efficient remanence acquisition, exist in significant concentration, allowing a more comprehensive explanation of Martian <span class="hlt">anomalies</span> and better insight into the role of remanent <span class="hlt">magnetization</span> in terrestrial crustal <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19850023278&hterms=Rhyolite&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DRhyolite','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19850023278&hterms=Rhyolite&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DRhyolite"><span id="translatedtitle">The south-central United States <span class="hlt">magnetic</span> <span class="hlt">anomaly</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Starich, P. J.; Hinze, W. J.; Braile, L. W.</p> <p>1985-01-01</p> <p>A positive <span class="hlt">magnetic</span> <span class="hlt">anomaly</span>, which dominates the MAGSAT scalar field over the south-central United States, results from the superposition of <span class="hlt">magnetic</span> effects from several geologic sources and tectonic structures in the crust. The highly <span class="hlt">magnetic</span> basement rocks of this region show good correlation with increased crustal thickness, above average crustal velocity and predominantly negative free-air gravity <span class="hlt">anomalies</span>, all of which are useful constraints for modeling the <span class="hlt">magnetic</span> sources. The positive <span class="hlt">anomaly</span> is composed of two primary elements. The western-most segment is related to middle Proterozoic granite intrusions, rhyolite flows and interspersed metamorphic basement rocks in the Texas panhandle and eastern New Mexico. The <span class="hlt">anomaly</span> and the <span class="hlt">magnetic</span> crust are bounded to the west by the north-south striking Rio Grande Rift. The <span class="hlt">anomaly</span> extends eastward over the Grenville age basement rocks of central Texas, and is terminated to the south and east by the buried extension of the Ouachita System. The northern segment of the <span class="hlt">anomaly</span> extends eastward across Oklahoma and Arkansas to the Mississippi Embayment. It corresponds to a general positive <span class="hlt">magnetic</span> region associated with the Wichita Mountains igneous complex in south-central Oklahoma and 1.2 to 1.5 Ga. felsic terrane to the north.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JESS..tmp...31S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JESS..tmp...31S"><span id="translatedtitle">Basement configuration of KG offshore basin from <span class="hlt">magnetic</span> <span class="hlt">anomalies</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Subrahmanyam, V.; Swamy, K. V.; Raj, Neetha</p> <p>2016-04-01</p> <p>Marine <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> along three representative profiles falling between shelf break and continent-ocean boundary in the offshore Krishna-Godavari basin were quantitatively interpreted for understanding the nature and structure of the <span class="hlt">magnetic</span> basement using inversion technique. The interpretation of the <span class="hlt">anomalies</span> shows that the <span class="hlt">magnetic</span> basement lies deeper than the base of the sediments, i.e., acoustic basement identified by the seismic studies. This interpretation also shows that the <span class="hlt">magnetic</span> basement is faulted along the NW-SE direction with the upthrown side lying to the north of the <span class="hlt">anomaly</span> trend of this region. The coincidence of <span class="hlt">magnetizations</span> observed through the present interpretation with that of charnockites of neighbouring EGMB and onshore K-G basin areas indicates that EGMB geology (charnockites, granitic gneiss, etc.) extends up to COB in the offshore K-G basin.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_1");'>1</a></li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li class="active"><span>3</span></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_3 --> <div id="page_4" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li class="active"><span>4</span></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="61"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002AGUSMGP42A..13K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002AGUSMGP42A..13K"><span id="translatedtitle"><span class="hlt">Magnetic</span> <span class="hlt">anomalies</span> along the contact between sedimentary and igneous rocks:</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kletetschka, G.; Speer, A. J.; Wasilewski, P. J.</p> <p>2002-05-01</p> <p>Intrusion of the Liberty Hill granite (South Carolina) into the surrounding shale causes a distinct aureole along the metamorphic contact. The aureole is divided by five isograds, which are the result of a sequence of continuous reactions. One consequence of the continuous reactions is production of contrasting proportion of magnetite and exsolved titanohematite. The continuous change in the relative amounts of these two minerals, controls the <span class="hlt">magnetic</span> properties of the hornfelses. This causes <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> changes associated with the aureole with inflexions occurring at the isograds. The maximum intensity of the <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> coincides with the maximum abundance of titanohematite. The <span class="hlt">anomaly</span> sharply drops when stable remanence of titanohematite is replaced by unstable remanence of magnetite. <span class="hlt">Magnetic</span> properties of the aureole, which is the contact between igneous and sedimentary rocks, demonstrate an example of <span class="hlt">magnetic</span> remanence acquisition in petrological environment that is likely to occur on planet Mars.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFMGP21C0788H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFMGP21C0788H"><span id="translatedtitle"><span class="hlt">Magnetic</span> <span class="hlt">Anomalies</span> Antipodal to Large Impact Basins on the Moon</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hemant, K.; Purucker, M. E.</p> <p>2008-12-01</p> <p>The high resolution lunar-wide <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> map derived from Lunar Prospector (LP) vector magnetometer data has revealed weak <span class="hlt">anomalies</span> over the nearside large impact basins flooded by mare basalts. Strong <span class="hlt">anomaly</span> features are observed over most of the Nectarian and Pre-Nectarian aged lunar highlands. In particular, regions antipodal to some of the largest basin-forming impact craters show strong <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> concentrations. Of the 43 basins investigated here, antipodal regions of 11 basins show these anomalous features with strengths in excess of 5-25 nT at LP's mapping altitude (30 km). These distinct anomalous concentrations were previously known to occur only at the antipodes of Imbrium, Orientale, Serenitatis and Crisium basins. The mean <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> strength within each antipodal region when plotted against increasing age of the antipodes shows two age groupings with similar <span class="hlt">magnetic</span> behavior. The first age grouping - (Imbrium, Orientale, Serenitatis and Crisium) is of Imbrium to Late Nectarian in age. This grouping is correlative with the peak <span class="hlt">magnetic</span> field enhancement between 3.6 and 3.9 Gyr, inferred from paleomagnetic data from the returned Apollo samples. The second age grouping ( Lorentz, Coulomb-Sarton, Tranquillitatis, Cognitum and Insularum) is of Mid to Early Pre-Nectarian age. This grouping has not been correlated to any known global <span class="hlt">magnetic</span> field enhancement event, and needs further investigation to ascertain the origin of the <span class="hlt">anomalies</span>. The present work supports the antipodal hypothesis as one of the possible mechanisms to explain the observed <span class="hlt">anomalies</span> at the antipode of the impact basin. The absence of appreciable <span class="hlt">anomalies</span> at the 32 other antipodes, however, indicates the importance of other processes, and superposition effects, that have operated on the Moon during its history.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19830005257','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19830005257"><span id="translatedtitle">The mineralogy of global <span class="hlt">magnetic</span> <span class="hlt">anomalies</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Haggerty, S. E. (Principal Investigator)</p> <p>1982-01-01</p> <p>The Curie Balance was brought to operational stage and is producing data of a preliminary nature. Substantial problems experienced in the assembly and initial operation of the instrument were, for the most part, rectified, but certain problems still exist. Relationships between the geology and the gravity and MAGSAT <span class="hlt">anomalies</span> of West Africa are reexamined in the context of a partial reconstruction of Gondwanaland.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1982GeoRL...9..329W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1982GeoRL...9..329W"><span id="translatedtitle">Crustal xenolith <span class="hlt">magnetic</span> properties and long wavelength <span class="hlt">anomaly</span> source requirements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wasilewski, Peter; Mayhew, M. A.</p> <p>1982-04-01</p> <p>Granulite xenoliths, probable components of the lower continental crust, are a primary source of information about the <span class="hlt">magnetization</span> of the lower crust. <span class="hlt">Magnetization</span> values for lower crustal xenoliths from three tectonic settings (converging plate margin, rift valley, and continental intraplate region) demonstrate that metabasic rocks in the granulite facies have <span class="hlt">magnetization</span> values consistent with <span class="hlt">magnetizations</span> inferred for modeled sources of long wavelength <span class="hlt">anomalies</span>. Measured Curie points for granulite xenoliths are near 560-570°C except for those from rift zones and other regions where anhydrous, probably reducing lower crustal conditions exist in a steep geothermal gradient. In samples from the reducing environments Curie points <300°C are measured. The lower crust could be the most <span class="hlt">magnetic</span> crustal layer. Satellite <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> may serve to delineate <span class="hlt">magnetization</span> provinces which may be related to the tectonic and chemical evolution of continents.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19780003509','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19780003509"><span id="translatedtitle">A method of inversion of satellite <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> data</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mayhew, M. A.</p> <p>1977-01-01</p> <p>A method of finding a first approximation to a crustal <span class="hlt">magnetization</span> distribution from inversion of satellite <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> data is described. <span class="hlt">Magnetization</span> is expressed as a Fourier Series in a segment of spherical shell. Input to this procedure is an equivalent source representation of the observed <span class="hlt">anomaly</span> field. Instability of the inversion occurs when high frequency noise is present in the input data, or when the series is carried to an excessively high wave number. Preliminary results are given for the United States and adjacent areas.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19910067154&hterms=SUSCEPTIBILITY+MAGNETIC&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DSUSCEPTIBILITY%2BMAGNETIC','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19910067154&hterms=SUSCEPTIBILITY+MAGNETIC&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DSUSCEPTIBILITY%2BMAGNETIC"><span id="translatedtitle">Magsat <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> contrast across Labrador Sea passive margins</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bradley, Lauren M.; Frey, Herbert</p> <p>1991-01-01</p> <p>Many passive margins not complicated by nearby anomalous crustal structure have satellite elevation crustal <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> contrasts across them that are recognizable in reduced-to-pole versions of the Magsat and POGO data. In the Labrador Sea region this contrast is particularly well developed with strong positive <span class="hlt">anomalies</span> overlying the continental crust of Greenland and eastern Canada and prominent negative <span class="hlt">anomalies</span> situated over the Labrador Sea and Baffin Bay. In this work, forward modeling of the large-scale crustal bodies in this region (continental, oceanic, passive margin, several anomalous structures) was used to show that the Magsat <span class="hlt">anomaly</span> contrast is due simply to the change in crustal susceptibility and thickness at the continental/oceanic crustal transition. Because the thickness varies more than the average susceptibility from continental to oceanic crust, the strong <span class="hlt">anomaly</span> contrast is essentially an edge effect due mostly to the change in crustal structure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21457099','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21457099"><span id="translatedtitle">SEISMIC DISCRIMINATION OF THERMAL AND <span class="hlt">MAGNETIC</span> <span class="hlt">ANOMALIES</span> IN SUNSPOT UMBRAE</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lindsey, C.; Cally, P. S.; Rempel, M.</p> <p>2010-08-20</p> <p>Efforts to model sunspots based on helioseismic signatures need to discriminate between the effects of (1) a strong <span class="hlt">magnetic</span> field that introduces time-irreversible, vantage-dependent phase shifts, apparently connected to fast- and slow-mode coupling and wave absorption and (2) a thermal <span class="hlt">anomaly</span> that includes cool gas extending an indefinite depth beneath the photosphere. Helioseismic observations of sunspots show travel times considerably reduced with respect to equivalent quiet-Sun signatures. Simulations by Moradi and Cally of waves skipping across sunspots with photospheric <span class="hlt">magnetic</span> fields of order 3 kG show travel times that respond strongly to the <span class="hlt">magnetic</span> field and relatively weakly to the thermal <span class="hlt">anomaly</span> by itself. We note that waves propagating vertically in a vertical <span class="hlt">magnetic</span> field are relatively insensitive to the <span class="hlt">magnetic</span> field, while remaining highly responsive to the attendant thermal <span class="hlt">anomaly</span>. Travel-time measurements for waves with large skip distances into the centers of axially symmetric sunspots are therefore a crucial resource for discrimination of the thermal <span class="hlt">anomaly</span> beneath sunspot umbrae from the <span class="hlt">magnetic</span> <span class="hlt">anomaly</span>. One-dimensional models of sunspot umbrae based on compressible-radiative-<span class="hlt">magnetic</span>-convective simulations such as by Rempel et al. can be fashioned to fit observed helioseismic travel-time spectra in the centers of sunspot umbrae. These models are based on cooling of the upper 2-4 Mm of the umbral subphotosphere with no significant <span class="hlt">anomaly</span> beneath 4.5 Mm. The travel-time reductions characteristic of these models are primarily a consequence of a Wilson depression resulting from a strong downward buoyancy of the cooled umbral medium.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMOS23E..01L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMOS23E..01L"><span id="translatedtitle">First high-resolution near-seafloor survey of <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> of the South China Sea</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lin, J.; Xu, X.; Li, C.; Sun, Z.; Zhu, J.; Zhou, Z.; Qiu, N.</p> <p>2013-12-01</p> <p>We successfully conducted the first high-resolution near-seafloor <span class="hlt">magnetic</span> survey of the Central, Southwest, and Northern Central Basins of the South China Sea (SCS) during two cruises on board Chinese R/V HaiYangLiuHao in October-November 2012 and March-April 2013, respectively. Measurements of <span class="hlt">magnetic</span> field were made along four long survey lines, including (1) a NW-SE across-isochron profile transecting the Southwest Basin and covering all ages of the oceanic crust (Line CD); (2) a N-S across-isochron profile transecting the Central Basin (Line AB); and (3) two sub-parallel NE-SW across-isochron profiles transecting the Northern Central Basin of the SCS (Lines D and E). A three-axis magnetometer was mounted on a deep-tow vehicle, flying within 0.6 km above the seafloor. The position of the tow vehicle was provided by an ultra-short baseline navigation system along Lines D and E, while was estimated using shipboard GPS along Lines AB and CD. To investigate crustal <span class="hlt">magnetization</span>, we first removed the International Geomagnetic Reference Field (IGRF) of 2010 from the measured <span class="hlt">magnetic</span> data, and then downward continued the resultant <span class="hlt">magnetic</span> field data to a horizontal plane at a water depth of 4.5 km to correct for variation due to the fishing depth of the deep-tow vehicle. Finally, we calculated <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> at various water depths after reduction-to-the-pole corrections. We also constructed polarity reversal block (PRB) models of crustal <span class="hlt">magnetization</span> by matching peaks and troughs of the observed <span class="hlt">magnetic</span> field <span class="hlt">anomaly</span>. Our analysis yielded the following results: (1) The near-bottom <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> showed peak-to-trough amplitudes of more than 2,500 nT, which are several times of the <span class="hlt">anomaly</span> amplitudes at the sea surface, illustrating that deep-tow measurements acquired much higher spatial resolutions. (2) The deep-tow data revealed several distinctive <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> with wavelengths of 5-15 km and amplitudes of several hundred nT. These short-wavelength <span class="hlt">anomalies</span> were unrecognized in sea surface measurements. (3) Preliminary results showed that the study regions might have experienced several episodes of <span class="hlt">magnetic</span> reversal events that were not recognized in existing models. (4) We are currently investigating the geomagnetic timing of these relatively short-duration events to determine the detailed <span class="hlt">spreading</span> history of the sub-basins of the SCS. These high-resolution near-seafloor <span class="hlt">magnetic</span> survey lines are located close to the planned drilling sites of IODP Expedition 349 scheduled for January-March 2014.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.T23G2679K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.T23G2679K"><span id="translatedtitle">The early break-up phase of the South Atlantic - <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>, volcanism and kinematics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Koopmann, H.; Schreckenberger, B.; Franke, D.; Becker, K.; Schnabel, M.</p> <p>2013-12-01</p> <p>The South Atlantic has been generally recognized as a prime example for continental break-up with accompanying volcanic activity reflected today in massive seaward dipping reflector sequences (SDRS) in reflection as well as high velocity lower crust in refraction seismic data. The early history of the South Atlantic passive margin evolution is investigated in the view of interlaced <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> related to seafloor <span class="hlt">spreading</span> lineations and <span class="hlt">anomalies</span> caused by seaward-dipping reflector sequences (SDRS). As the Atlantic opened from South to North, the magma-poor segments of the southernmost South Atlantic are also the oldest segments of the Ocean. Therefore, the magma-poor segments on the conjugated margins must be considered crucial in the understanding of the initial phase of <span class="hlt">spreading</span> and rifting concluding in the opening of the South Atlantic. The interpretation of pre-M5n lineations define timing of the termination of excess breakup related volcanic activity and the transition to 'normal' seafloor <span class="hlt">spreading</span>. Termination of <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> within SDR wedges point towards a scissor-like succession in volcanic activity from south to north, following the opening of the South Atlantic. Reflection, refraction seismic and potential field data show that while the two conjugated margins share much of their structural features such as segmentation and abundant volcanism, they are by no means perfectly symmetrical. This is for example shown in shelf width, strength of the <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> or orientation of break-up related sedimentary basins. From our data, we suggest changes in <span class="hlt">spreading</span> and later rifting direction to be the cause of for these asymmetries. This directional change is also suggested to be responsible for the change in margin character from magma-poor to volcanic rather than solely a spontaneous change in crustal melt-generation. New models for the <span class="hlt">magnetic</span> response of SDRS reveal a high variability within the wedges on either side of the Atlantic and between the conjugated margins. Former identifications of <span class="hlt">anomaly</span> M11r off Cape Town have already been questioned and can now be shown to be caused by structural or <span class="hlt">magnetization</span> variations within SDRS.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930016012','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930016012"><span id="translatedtitle">Improved determination of vector lithospheric <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> from MAGSAT data</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ravat, Dhananjay</p> <p>1993-01-01</p> <p>Scientific contributions made in developing new methods to isolate and map vector <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> from measurements made by Magsat are described. In addition to the objective of the proposal, the isolation and mapping of equatorial vector lithospheric Magsat <span class="hlt">anomalies</span>, isolation of polar ionospheric fields during the period were also studied. Significant progress was also made in isolation of polar delta(Z) component and scalar <span class="hlt">anomalies</span> as well as integration and synthesis of various techniques of removing equatorial and polar ionospheric effects. The significant contributions of this research are: (1) development of empirical/analytical techniques in modeling ionospheric fields in Magsat data and their removal from uncorrected <span class="hlt">anomalies</span> to obtain better estimates of lithospheric <span class="hlt">anomalies</span> (this task was accomplished for equatorial delta(X), delta(Z), and delta(B) component and polar delta(Z) and delta(B) component measurements; (2) integration of important processing techniques developed during the last decade with the newly developed technologies of ionospheric field modeling into an optimum processing scheme; and (3) implementation of the above processing scheme to map the most robust <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> of the lithosphere (components as well as scalar).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/16484488','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/16484488"><span id="translatedtitle">Plasma acceleration above martian <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lundin, R; Winningham, D; Barabash, S; Frahm, R; Holmström, M; Sauvaud, J-A; Fedorov, A; Asamura, K; Coates, A J; Soobiah, Y; Hsieh, K C; Grande, M; Koskinen, H; Kallio, E; Kozyra, J; Woch, J; Fraenz, M; Brain, D; Luhmann, J; McKenna-Lawler, S; Orsini, R S; Brandt, P; Wurz, P</p> <p>2006-02-17</p> <p>Auroras are caused by accelerated charged particles precipitating along <span class="hlt">magnetic</span> field lines into a planetary atmosphere, the auroral brightness being roughly proportional to the precipitating particle energy flux. The Analyzer of Space Plasma and Energetic Atoms experiment on the Mars Express spacecraft has made a detailed study of acceleration processes on the nightside of Mars. We observed accelerated electrons and ions in the deep nightside high-altitude region of Mars that map geographically to interface/cleft regions associated with martian crustal <span class="hlt">magnetization</span> regions. By integrating electron and ion acceleration energy down to the upper atmosphere, we saw energy fluxes in the range of 1 to 50 milliwatts per square meter per second. These conditions are similar to those producing bright discrete auroras above Earth. Discrete auroras at Mars are therefore expected to be associated with plasma acceleration in diverging <span class="hlt">magnetic</span> flux tubes above crustal <span class="hlt">magnetization</span> regions, the auroras being distributed geographically in a complex pattern by the many multipole <span class="hlt">magnetic</span> field lines extending into space. PMID:16484488</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19850035867&hterms=Seamounts&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DSeamounts','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19850035867&hterms=Seamounts&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DSeamounts"><span id="translatedtitle">Intermediate-wavelength <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> over the central Pacific</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Labrecque, J. L.; Cande, S. C.</p> <p>1984-01-01</p> <p>A technique to extract the intermediate wavelength <span class="hlt">anomaly</span> field from random ship tracks has been developed and is applied to extract the field from marine survey data of the central Pacific in the band pass of 4000-400 km. The technique minimizes the effects of external field sources, secular variation, and strike aliasing. The derived data field is compared to the equivalent MAGSAT data set, and it is shown that <span class="hlt">anomalies</span> observed in both fields are correlatable to geologic features within the oceanic lithosphere but differ in amplitude by a factor of two. Likely sources for this discrepancy are identified. It is also shown that remanent <span class="hlt">magnetization</span> of the central Pacific seamounts produces negative <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> which are observed at satellite altitude.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.T51E2378G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.T51E2378G"><span id="translatedtitle">Understanding the Tectonic Features in the South China Sea By Analyzing <span class="hlt">Magnetic</span> <span class="hlt">Anomalies</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Guo, L.; Meng, X.; Shi, L.; Yao, C.</p> <p>2011-12-01</p> <p>The South China Sea (SCS) is surrounded by the Eurasia, Pacific and India-Australia plates. It formed during Late Oligocene-Early Miocene, and is one of the largest marginal seas in the Western Pacific. The collision of Indian subcontinent and Eurasian plate in the northwest, back-arc <span class="hlt">spreading</span> in the centre and subduction beneath the Philippine plate along Manila trench in the east and along Palawan trough in the south had produced the complex tectonic features in the SCS that we can see today. In the past few decades, a variety of geophysical methods were conducted to study geological tectonics and evolution of the SCS. Here, we analyzed the <span class="hlt">magnetic</span> data of this area using new data enhancement techniques to understand the regional tectonic features. We assembled the <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> data with a resolution of two arc-minute from the World Digital <span class="hlt">Magnetic</span> <span class="hlt">Anomaly</span> Map, and then gridded the data on a regular grid. Then we used the method of reduction to the pole at low latitude with varying <span class="hlt">magnetic</span> inclinations to stably reduce the <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>. Then we used the preferential continuation method based on Wiener filtering and Green's equivalence principle to separate the reduced-to-pole (RTP) <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>, and subsequently analyze the regional and residual <span class="hlt">anomalies</span>. We also calculated the directional horizontal derivatives and the tilt-angle derivative of the data to derive clearer geological structures with more details. Then we calculated the depth of the <span class="hlt">magnetic</span> basement surface in the area by 3D interface inversion. From the results of the preliminary processing, we analyzed the main faults, geological structures, magma distribution and tectonic features in the SCS. In the future, the integrated interpretation of the RTP <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>, Bouguer gravity <span class="hlt">anomalies</span> and other geophysical methods will be performed for better understanding the deep structure , the tectonic features and evolution of the South China Sea. Acknowledgment: We acknowledge the financial support of the SinoProbe project (201011039), the Fundamental Research Funds for the Central Universities (2010ZY26, 2011PY0184), and the National Natural Science Foundation of China (40904033, 41074095).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/ofr20071047SRP050','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/ofr20071047SRP050"><span id="translatedtitle">New <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> map of East Antarctica and surrounding regions</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Golynsky, A.; Blankenship, D.; Chiappini, M.; Damaske, D.; Ferraccioli, F.; Finn, C.; Golynsky, D.; Goncharov, A.; Ishihara, T.; Ivanov, S.; Jokat, W.; Kim, H.R.; König, M.; Masolov, V.; Nogi, Y.; Sand, M.; Studing, M.; ADMAP Working Group</p> <p>2007-01-01</p> <p>community over East Antarctica and surrounding regions, significantly upgrade the Antarctic Digital <span class="hlt">Magnetic</span> <span class="hlt">Anomaly</span> Project (ADMAP) compilation and lead to substantial improvements in <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> pattern recognition. New data have been matched in one inverse operation by minimizing the data differences for the areas of overlap. The aeromagnetic data show many previously unknown <span class="hlt">magnetic</span> patterns, lineaments and trends, defining the spatial extent of Ferrar volcanics and plutonic Granite Harbour Intrusives in the Transantarctic Mountains and previously unknown tectonic trends of the East Antarctic craton. Regional aeromagnetic investigations have successfully delineated Early Paleozoic inherited crustal features along the flanks of the West Antarctic Rift System and the southern boundary of the Archean Ruker Terrane in the Prince Charles Mountains. <span class="hlt">Magnetic</span> records along the East Antarctic continental margin provide new constraints on the breakup of Gondwana.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/ofr20071047SRP093','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/ofr20071047SRP093"><span id="translatedtitle">The next generation Antarctic digital <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> map</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>von Frese, R.R.B; Golynsky, A.V.; Kim, H.R.; Gaya-Piqué, L.; Thébault, E.; Chiappinii, M.; Ghidella, M.; Grunow, A.; ADMAP Working Group</p> <p>2007-01-01</p> <p>S (Golynsky et al., 2001). This map synthesized over 7.1 million line-kms of survey data available up through 1999 from marine, airborne and Magsat satellite observations. Since the production of the initial map, a large number of new marine and airborne surveys and improved <span class="hlt">magnetic</span> observations from the Ørsted and CHAMP satellite missions have become available. In addition, an improved core field model for the Antarctic has been developed to better isolate crustal <span class="hlt">anomalies</span> in these data. The next generation compilation also will likely represent the <span class="hlt">magnetic</span> survey observations of the region in terms of a high-resolution spherical cap harmonic model. In this paper, we review the progress and problems of developing an improved <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> map to facilitate studies of the Antarctic crustal <span class="hlt">magnetic</span> field</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70015190','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70015190"><span id="translatedtitle">Approximating edges of source bodies from <span class="hlt">magnetic</span> or gravity <span class="hlt">anomalies</span>.</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Blakely, R.J.; Simpson, R.W.</p> <p>1986-01-01</p> <p>Cordell and Grauch (1982, 1985) discussed a technique to estimate the location of abrupt lateral changes in <span class="hlt">magnetization</span> or mass density of upper crustal rocks. The final step of their procedure is to identify maxima on a contoured map of horizontal gradient magnitudes. Attempts to automate their final step. The method begins with gridded <span class="hlt">magnetic</span> or gravity <span class="hlt">anomaly</span> data and produces a plan view of inferred boundaries of <span class="hlt">magnetic</span> or gravity sources. The method applies to both local surveys and to continent-wide compilations of <span class="hlt">magnetic</span> and gravity data.-from Authors</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1712162L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1712162L"><span id="translatedtitle"><span class="hlt">Magnetic</span> properties of Mauritanian BIFs: constraints on the source of the West Africa <span class="hlt">magnetic</span> field <span class="hlt">anomaly</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Launay, Nicolas; Quesnel, Yoann; Rochette, Pierre</p> <p>2015-04-01</p> <p>The ESA Swarm mission was launched in 2013 to produce a set of data with an unprecedented level of precision concerning the Earth's <span class="hlt">magnetic</span> field, and in particular the crustal field. Our objective is to use these data in order to create a three-dimensional model of the crustal sources of some of earth's most important <span class="hlt">magnetic</span> field <span class="hlt">anomalies</span>: the West African and Bangui <span class="hlt">anomalies</span>. To achieve this goal and properly constrain our model, we need to study the <span class="hlt">magnetic</span> properties of the African Banded Iron Formation rocks, known as the most <span class="hlt">magnetic</span> component of this continent's crust, and thus the most probable source of the <span class="hlt">anomalies</span>. The remanent <span class="hlt">magnetization</span> - both with and without thermal demagnetization - and <span class="hlt">magnetic</span> susceptibility were measured on a wide set of BIF samples from the Kediet ej Jill in Mauritania. The data obtained will allow us to constrain a source model for the West African <span class="hlt">magnetic</span> <span class="hlt">anomaly</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/17731490','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/17731490"><span id="translatedtitle">Macquarie island and the cause of oceanic linear <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Varne, R; Gee, R D; Quilty, P G</p> <p>1969-10-10</p> <p>Macquarie Islands is formed of probably Pliocene oceanic crust. Intruded into pillow lavas is a belt of harzburgite and layered gabbro mnasses cut by dike swarms. Similar belt-like structures may cause the linear <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> of the ocean. PMID:17731490</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1999msls.work...35G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1999msls.work...35G"><span id="translatedtitle">Potential Mars 2001 Sites Coincident with <span class="hlt">Magnetic</span> <span class="hlt">Anomalies</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gilmore, M. S.</p> <p>1999-06-01</p> <p>Of the areas that meet the engineering criteria for MSP 01, only two are coincident with <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> measured by the MAG/ER instrument on MGS. Area A is centered on about 10 deg S, 202 deg W and extends from about 7.5 deg S to 15 S. This area is associated with three bands of <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>, two with positive values surrounding an area with negative values. Area B corresponds with a circular high positive <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> and is centered at 13.5 deg S, 166 deg W. In addition to <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>, the proposed sites have other attributes that make then attractive from of standpoint of meeting the objectives of the Mars Program. The landing site candidates meet the engineering requirements outlined on the Mars '01 landing site page htip://mars.jpl.nasa.gov/2001/landingsite. These are (source of data in parentheses): latitude between 3 deg N and 12 deg S, rock abundance between 5-10% (IRTM), fine-component thermal inertia > 4 cgs units (IRTM), topography < 2.5 km (MOLA). There are three exceptions: 1) Area B contains sites that lie up to about 15 deg S, 2) some sites are considered that have rock abundance values of 3-13%. 3) High resolution Viking coverage may not be available. These exceptions will be noted.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20010013023&hterms=Mars+attributes&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DMars%2Battributes','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20010013023&hterms=Mars+attributes&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DMars%2Battributes"><span id="translatedtitle">Potential Mars 2001 Sites Coincident with <span class="hlt">Magnetic</span> <span class="hlt">Anomalies</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gilmore, M. S.</p> <p>1999-01-01</p> <p>Of the areas that meet the engineering criteria for MSP 01, only two are coincident with <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> measured by the MAG/ER instrument on MGS. Area A is centered on about 10 deg S, 202 deg W and extends from about 7.5 deg S to 15 S. This area is associated with three bands of <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>, two with positive values surrounding an area with negative values. Area B corresponds with a circular high positive <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> and is centered at 13.5 deg S, 166 deg W. In addition to <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>, the proposed sites have other attributes that make then attractive from of standpoint of meeting the objectives of the Mars Program. The landing site candidates meet the engineering requirements outlined on the Mars '01 landing site page htip://mars.jpl.nasa.gov/2001/landingsite. These are (source of data in parentheses): latitude between 3 deg N and 12 deg S, rock abundance between 5-10% (IRTM), fine-component thermal inertia > 4 cgs units (IRTM), topography < 2.5 km (MOLA). There are three exceptions: 1) Area B contains sites that lie up to about 15 deg S, 2) some sites are considered that have rock abundance values of 3-13%. 3) High resolution Viking coverage may not be available. These exceptions will be noted.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li class="active"><span>4</span></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_4 --> <div id="page_5" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li class="active"><span>5</span></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="81"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/993054','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/993054"><span id="translatedtitle">Axial <span class="hlt">Anomaly</span>, Dirac Sea, and the Chiral <span class="hlt">Magnetic</span> Effect</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kharzeev, D.E.</p> <p>2010-05-26</p> <p>Gribov viewed the axial <span class="hlt">anomaly</span> as a manifestation of the collective motion of Dirac fermions with arbitrarily high momenta in the vacuum. In the presence of an external <span class="hlt">magnetic</span> field and a chirality imbalance, this collective motion becomes directly observable in the form of the electric current - this is the chiral <span class="hlt">magnetic</span> effect (CME). I give an elementary introduction into the physics of CME, and discuss the experimental status and recent developments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19840020207','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19840020207"><span id="translatedtitle">Petrologic and geophysical sources of long-wavelength crustal <span class="hlt">magnetic</span> <span class="hlt">anomalies</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Marsh, B. D.; Schlinger, C. M.</p> <p>1984-01-01</p> <p>The <span class="hlt">magnetic</span> mineralogy and <span class="hlt">magnetic</span> properties of the deep crust are studied as they pertain to the interpretation of long wavelength, or regional, crustal <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> in satellite <span class="hlt">magnetic</span> data and near surface <span class="hlt">magnetic</span> data. The conclusions have relevance to the understanding of regional <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> in <span class="hlt">magnetic</span> field measuring satellite missions data. There are two separable studies: (1) a synthesis of available information of regional <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> and the <span class="hlt">magnetization</span> of metamorphic and igneous rocks, and (2) a detailed field, analytical, and experimental study of in situ and laboratory specimens from a terrain that offers exposures of high grade granlite facies rocks that have associated regional <span class="hlt">magnetic</span> and gravity <span class="hlt">anomalies</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70012575','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70012575"><span id="translatedtitle">Lunar <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> detected by the Apollo substatellite magnetometers</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Hood, L.L.; Coleman, P.J., Jr.; Russell, C.T.; Wilhelms, D.E.</p> <p>1979-01-01</p> <p>Properties of lunar crustal <span class="hlt">magnetization</span> thus far deduced from Apollo subsatellite magnetometer data are reviewed using two of the most accurate presently available <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> maps - one covering a portion of the lunar near side and the other a part of the far side. The largest single <span class="hlt">anomaly</span> found within the region of coverage on the near-side map correlates exactly with a conspicuous, light-colored marking in western Oceanus Procellarum called Reiner Gamma. This feature is interpreted as an unusual deposit of ejecta from secondary craters of the large nearby primary impact crater Cavalerius. An age for Cavalerius (and, by implication, for Reiner Gamma) of 3.2 ?? 0.2 ?? 109 y is estimated. The main (30 ?? 60 km) Reiner Gamma deposit is nearly uniformly <span class="hlt">magnetized</span> in a single direction, with a minimum mean <span class="hlt">magnetization</span> intensity of ???7 ?? 10-2 G cm3/g (assuming a density of 3 g/cm3), or about 700 times the stable <span class="hlt">magnetization</span> component of the most <span class="hlt">magnetic</span> returned samples. Additional medium-amplitude <span class="hlt">anomalies</span> exist over the Fra Mauro Formation (Imbrium basin ejecta emplaced ???3.9 ?? 109 y ago) where it has not been flooded by mare basalt flows, but are nearly absent over the maria and over the craters Copernicus, Kepler, and Reiner and their encircling ejecta mantles. The mean altitude of the far-side <span class="hlt">anomaly</span> gap is much higher than that of the near-side map and the surface geology is more complex, so individual <span class="hlt">anomaly</span> sources have not yet been identified. However, it is clear that a concentration of especially strong sources exists in the vicinity of the craters Van de Graaff and Aitken. Numerical modeling of the associated fields reveals that the source locations do not correspond with the larger primary impact craters of the region and, by analogy with Reiner Gamma, may be less conspicuous secondary crater ejecta deposits. The reason for a special concentration of strong sources in the Van de Graaff-Aitken region is unknown, but may be indirectly related to the existence of strongly modified crustal terrain which also occurs in the same region. The inferred directions of <span class="hlt">magnetization</span> for the several sources of the largest <span class="hlt">anomalies</span> are highly inclined with respect to one another, but are generally depleted in the north-south direction. The north-south depletion of <span class="hlt">magnetization</span> intensity appears to continue across the far-side within the region of coverage. The mechanism of <span class="hlt">magnetization</span> and the origin of the <span class="hlt">magnetizing</span> field remain unresolved, but the uniformity with which the Reiner Gamma deposit is apparently <span class="hlt">magnetized</span>, and the north-south depletion of <span class="hlt">magnetization</span> intensity across a substantial portion of the far side, seem to require the existence of an ambient field, perhaps of global or larger extent. The very different inferred directions of <span class="hlt">magnetization</span> possessed by nearly adjacent sources of the Van de Graaff-Aitken <span class="hlt">anomalies</span>, and the depletion in their north-south component of <span class="hlt">magnetization</span>, do not favor an internally generated dipolar field oriented parallel to the present spin axis. A variably oriented interplanetary <span class="hlt">magnetizing</span> field that was intrinsically strong or locally amplified by unknown surface processes is least inconsistent with the data. ?? 1979.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19770018759','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19770018759"><span id="translatedtitle">On the origin of the Bangui <span class="hlt">magnetic</span> <span class="hlt">anomaly</span>, central African empire</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Marsh, B. D.</p> <p>1977-01-01</p> <p>A large <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> was recognized in satellite magnetometer data over the Central African Empire in central Africa. They named this <span class="hlt">anomaly</span> the Bangui <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> due to its location near the capital city of Bangui, C.A.E. Because large crustal <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> are uncommon, the origin of this <span class="hlt">anomaly</span> has provoked some interest. The area of the <span class="hlt">anomaly</span> was visited to make ground <span class="hlt">magnetic</span> measurements, geologic observations, and in-situ <span class="hlt">magnetic</span> susceptibility measurements. Some rock samples were also collected and chemically analyzed. The results of these investigations are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/873116','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/873116"><span id="translatedtitle">Low energy <span class="hlt">spread</span> ion source with a coaxial <span class="hlt">magnetic</span> filter</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Leung, Ka-Ngo; Lee, Yung-Hee Yvette</p> <p>2000-01-01</p> <p>Multicusp ion sources are capable of producing ions with low axial energy <span class="hlt">spread</span> which are necessary in applications such as ion projection lithography (IPL) and radioactive ion beam production. The addition of a radially extending <span class="hlt">magnetic</span> filter consisting of a pair of permanent <span class="hlt">magnets</span> to the multicusp source reduces the energy <span class="hlt">spread</span> considerably due to the improvement in the uniformity of the axial plasma potential distribution in the discharge region. A coaxial multicusp ion source designed to further reduce the energy <span class="hlt">spread</span> utilizes a cylindrical <span class="hlt">magnetic</span> filter to achieve a more uniform axial plasma potential distribution. The coaxial <span class="hlt">magnetic</span> filter divides the source chamber into an outer annular discharge region in which the plasma is produced and a coaxial inner ion extraction region into which the ions radially diffuse but from which ionizing electrons are excluded. The energy <span class="hlt">spread</span> in the coaxial source has been measured to be 0.6 eV. Unlike other ion sources, the coaxial source has the capability of adjusting the radial plasma potential distribution and therefore the transverse ion temperature (or beam emittance).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19860029410&hterms=SUSCEPTIBILITY+MAGNETIC&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DSUSCEPTIBILITY%2BMAGNETIC','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19860029410&hterms=SUSCEPTIBILITY+MAGNETIC&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DSUSCEPTIBILITY%2BMAGNETIC"><span id="translatedtitle"><span class="hlt">Magnetization</span> of lower crust and interpretation of regional <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> - Example from Lofoten and Vesteralen, Norway</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Schlinger, C. M.</p> <p>1985-01-01</p> <p>During the last 20 years, studies have been conducted regarding the regional, or long-wavelength, geomagnetic <span class="hlt">anomalies</span> of the lower crust of the earth. The present paper is mainly concerned with the petrologic and geophysical interpretation of the observed features. Attention is given to <span class="hlt">magnetic</span> mineralogy and <span class="hlt">magnetic</span> properties of high-grade rocks from Lofoten and Vesteralen, regional geology and geophysics, field measurements and sampling, <span class="hlt">magnetic</span> mineralogy of the lower crust, the effects of metamorphism upon <span class="hlt">magnetic</span> mineralogy and <span class="hlt">magnetic</span> properties of high-grade rocks, susceptibility-temperature relations and the Hopkinson effect, and petrologic sources of regional crustal <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=UFO&id=EJ588347','ERIC'); return false;" href="http://eric.ed.gov/?q=UFO&id=EJ588347"><span id="translatedtitle"><span class="hlt">Anomalies</span>.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Online-Offline, 1999</p> <p>1999-01-01</p> <p>This theme issue on <span class="hlt">anomalies</span> includes Web sites, CD-ROMs and software, videos, books, and additional resources for elementary and junior high school students. Pertinent activities are suggested, and sidebars discuss UFOs, animal <span class="hlt">anomalies</span>, and <span class="hlt">anomalies</span> from nature; and resources covering unexplained phenonmenas like crop circles, Easter Island,…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=ufo&id=EJ588347','ERIC'); return false;" href="http://eric.ed.gov/?q=ufo&id=EJ588347"><span id="translatedtitle"><span class="hlt">Anomalies</span>.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Online-Offline, 1999</p> <p>1999-01-01</p> <p>This theme issue on <span class="hlt">anomalies</span> includes Web sites, CD-ROMs and software, videos, books, and additional resources for elementary and junior high school students. Pertinent activities are suggested, and sidebars discuss UFOs, animal <span class="hlt">anomalies</span>, and <span class="hlt">anomalies</span> from nature; and resources covering unexplained phenonmenas like crop circles, Easter Island,</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016CG.....90..179C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016CG.....90..179C"><span id="translatedtitle">Matched filtering method for separating <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> using fractal model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, Guoxiong; Cheng, Qiuming; Zhang, Henglei</p> <p>2016-05-01</p> <p>Fractal/scaling distribution of <span class="hlt">magnetization</span> in the crust has found with growing body of evidences from spectral analysis of borehole susceptibility logs and <span class="hlt">magnetic</span> field data, and fractal properties of <span class="hlt">magnetic</span> sources have already been considered in processing <span class="hlt">magnetic</span> data such as the Spector and Grant method for depth determination. In this study, the fractal-based matched filtering method is presented for separating <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> caused by fractal sources. We argue the benefits of considering fractal natures of source distribution for data processing in <span class="hlt">magnetic</span> exploration: the first is that the depth determination can be improved by using multiscaling model to interpret the <span class="hlt">magnetic</span> data power spectrum; the second is that the matched filtering can be reconstructed by employing the difference in scaling exponent together with the corrected depth and amplitude estimates. In the application of synthetic data obtained from fractal modeling and real aeromagnetic data from the Qikou district of China, the proposed fractal-based matched filtering method obtains more reliable depth estimations as well as improved separation between local <span class="hlt">anomalies</span> (caused by volcanic rocks) and regional field (crystalline basement) in comparison with the conventional matched filtering method.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..12.6575L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..12.6575L"><span id="translatedtitle">Manifestation of the petrogeneration zones of Northern and the Bering seas in ground <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> and <span class="hlt">anomalies</span> of satellite Champ</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Litvinova, Tamara; Krasinsky, Egor; Petrova, Alevtina; Demina, Irina</p> <p>2010-05-01</p> <p>The purpose of this paper are showed results of studying of specificity of a deep structure of zones of petrogeneration Northern and the Bering seas on aeromagnetic and satellite magnetometric datas. Research lateral and vertical heterogeneitys an earth's crust of Northern sea is carried out on the basis of the analysis of measurements of satellite Champ at height of 100 km and the digital database created on materials of sea shooting of a geomagnetic field, executed on non-<span class="hlt">magnetic</span> schooner "Zarya". On sea measurements in Northern sea through large oil fields and gas ( Frigg, Ekofisk, Forties trough, Leman, etc.). Geomagnetic sections for an interval of depths from 1 up to 30 km are constructed. It has allowed to study character of distribution of <span class="hlt">magnetization</span> of breeds of a cover, horizontal lamination intracore layers of an earth's crust and to allocate in zones petrogeneration synvertical fluidoconduct zones the channels described by alternation of not <span class="hlt">magnetic</span> and low-<span class="hlt">magnetic</span> layers. They were showed on geomagnetic sections as permeable zones quasi- laminated structures with the lowered <span class="hlt">magnetic</span> properties in an interval of depths from 8 up to 28 km. Comparison to a map of the <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> measured at height of 100 km by satellite Champ, has shown, that areas of the greatest petrocongestions North Sea рифта at height of 100 km are dated for a zone of gradients and a minimum of northeast displacement of regional <span class="hlt">anomalies</span> of western and east blocks of Northern sea. It corresponds to representations about an orientation of a fissuring zone and the increased size of a geothermal gradient North Sea rift and is corresponded position allocated on hydromagnetic structures deep fluidoconduct channels. Thus, distribution to water areas of deposits of deposits is emphasized not only low-<span class="hlt">magnetic</span> areas in a thickness of a sedimentary cover where they are directly located, but also by not <span class="hlt">magnetic</span> lenses in breeds of the base <span class="hlt">spreading</span> it in intervals of depths of 8-11 km and 15-18 km. The oil-gas-bearing province of the Bering Sea occupies uniform sedimentary megabasin. On aeromagnetic measurements at height of 300 m are constructed geomagnetic sections in an interval of depths from 0.5 km up to 25 km crossing the basic zones possible petrocongestions with traps structural and of structural - stratigraphic types. Distribution of <span class="hlt">magnetization</span> in an interval of development of potentially productive sandy layers on depths from 1 up to 5 km is received. The most perspective zones possible petrocongestions are allocated in Ilpinsky, Olutorsky and Olutorsko-Komandorsky sedimentary basins. The deep permeable zone with system of low-<span class="hlt">magnetic</span> lenses in intervals of depths 8-10, 12, 18-20 km, dated to Pilgin zone possible petrocongestions was most brightly showed. Comparison of ground supervision to the data received by results of measurements from satellite Champ at height of 100 km, shows, that large oil-gas-bearing Vertuhovskaya, Karaginskaya, Pahachiskaya and Pilginskaya zones are dated for a minimum isometric satellite <span class="hlt">magnetic</span> <span class="hlt">anomaly</span>. At height of 400 km this minimum keeps the form that speaks about stability of a condition of the permeable zones supervising oil-gas-bearing.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMGP13A1141F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMGP13A1141F"><span id="translatedtitle">Marine <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> and <span class="hlt">magnetization</span> of subducting Pacific Plate around the Japan Trench</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fujiwara, T.</p> <p>2013-12-01</p> <p>We studied marine <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> in the northwestern margin of the Pacific Plate off Japan to examine whether the <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> varies due to tectonic phenomenon caused by the plate subduction. For the sake of this study, we newly collected <span class="hlt">magnetic</span> data aboard JAMSTEC cruises in the seaward area where was sparsely surveyed, and made a <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> map by compilation of our data, data published by Geological Survey of Japan, and data from NGDC. The seafloor of the seaward slope of the Japan Trench is characterized by a series of parallel <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> (Japanese Lineation Set) during M11-M7 (135-127 Ma). The <span class="hlt">anomalies</span> are well lineated and have high-amplitudes of ~500-1000 nT peak-to-trough. The amplitudes of the <span class="hlt">anomalies</span> gradually decay to the landward from the trench axis associated with the plate subduction. Equivalent <span class="hlt">magnetization</span> was calculated from the <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> to correct for effects of seafloor topography and increasing depth of subducting plate. Densely distributed seismic survey profiles in the study area enabled us to constrain the depth of the plate. On the seaward trench slope from the trench axis to a distance of ca. 100 km, horst-graben structure is developed and large steps grow associated with plate bending and normal faulting, which would cause some kind of destruction and mechanical disorganization of the <span class="hlt">magnetic</span> layer by faulting. However, the <span class="hlt">magnetization</span> is not influenced apparently there. The <span class="hlt">magnetization</span> gradually decreases as the plate subduction proceeded. The apparent decay could reflect destruction and mechanical disorganization and/or chemical demagnetization of the topmost part of the oceanic crust along the plate boundary. The <span class="hlt">magnetization</span> in reverse polarity decays larger than that in normal polarity. The result is indicative of reduction of remanence in the oceanic crust and induced <span class="hlt">magnetization</span> possibly due to serpentinized uppermost mantle.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUFMGP33D1598L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUFMGP33D1598L"><span id="translatedtitle">Mesozoic Kinematic Evolution of the Central Atlantic Inferred From Regional <span class="hlt">Magnetic</span> <span class="hlt">Anomalies</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Labails, C.; Olivet, J.; Aslanian, D.; Sichler, B.; Roest, W.; Evain, M.</p> <p>2007-12-01</p> <p>The <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> signature of Central Atlantic margins is well defined by the gridded data published by Verhoef et al. (1996) on the North American region. However, a gridded dataset for the West African margin (South of the Canary Islands) was lacking. We have used <span class="hlt">magnetic</span> data from the Geodas database, an Ifremer dataset and personnal communication from H.A. Roeser and W.J.M. Van der Linden in order to produce a gridded <span class="hlt">magnetic</span> data of the Dakhla margin and to better constrain the kinematics of Central Atlantic early opening. Our model adopts the breakup timing of 195 Ma as proposed by Sahabi et al. (2004) - 20 myr earlier than what was generally proposed in previous models. According to our interpretation of the newly compiled <span class="hlt">magnetic</span> data, the early opening of Central Atlantic was characterized by three distinct phases. In contrast to other models, we propose that for the first 30 myr (195-165 Ma, Lias-Dogger) the oceanic accretion was extremely slow (~0.8 cm/y). At the Blake Spur time, (around 165 Ma, Callovian basis), a drastic change occurred, both in the relative plate motions (initially NNW-SSE, it becomes NO-SE) and <span class="hlt">spreading</span> rate (that increases up to ~ 4.8 cm/y). The BSMA (Blake Spur <span class="hlt">Magnetic</span> <span class="hlt">Anomaly</span>) is related to a great basement topographic change. From <span class="hlt">magnetic</span> chron M22 (150 Ma, Tithonian basis) onwards, the <span class="hlt">spreading</span> rate slowed down to about 2.6 cm/y and remained constant until <span class="hlt">magnetic</span> chron M0 (125 Ma, Barremian-Aptian limit).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMGP13A1116K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMGP13A1116K"><span id="translatedtitle">High <span class="hlt">magnetic</span> susceptibility granodiorite as a source of surface <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> in the King George Island, Antarctica</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kon, S.; Nakamura, N.; Funaki, M.; Sakanaka, S.</p> <p>2012-12-01</p> <p>Change in plate motion produces convergence of the two oceanic lithospheres and the formation of volcanic island arcs above the subducted older and thicker plate. The association of calc-alkaline diorites to tonalites and granodiorites (ACG) is typical plutonic rocks of the volcanic arcs. In the many island arcs that surround the Pacific Ocean, ACG generally forms shallow level plutons and is closely associated with volcanic rocks. The Japan Arc setting had occurred the emplacement of the highly <span class="hlt">magnetic</span> granitoid along the fore-arc basin before back-arc <span class="hlt">spreading</span> at middle Miocene, showing a linear positive <span class="hlt">magnetic</span> <span class="hlt">anomaly</span>. Similar <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> have also been exhibited along the Circum-Pacific Belt. Along East Antarctica, it is well known that the South Shetland Islands have been formed by back-arc <span class="hlt">spreading</span> related to the subduction along the South Shetland trench during the late Cretaceous and middle Miocene. Moreover, geology in the South Shetland Islands consists of lava flows with subordinate pyroclastic deposits, intrusive dykes-sills, granitic plutons, displaying a typical subduction-related calc-alkaline volcanic association. However, there is little report on the presence of fore-arc granitoid. Here we report the distribution and structure of the granitic plutons around Marian Cove in the King George Island, South Shetland, East Antarctica by surface geological survey and <span class="hlt">magnetic</span> anisotropic studies. Then we compare the distribution of granitic plutons with surface <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> through our ship-borne and foot-borne <span class="hlt">magnetic</span> surveys. The granitic plutons are distributed only shallow around the Marian cove in the King George Island, and the plutons had been intruded in the Sejong formation with pyroclastic deposits and basaltic/rhyoritic lavas, suggesting the post back-arc <span class="hlt">spreading</span>. We sampled 8 plutons, 12 basaltic lavas and 6 andestic dykes, all located within four kilometer radius from the Korean Antarctic research station (King Sejong station) in the western side of King George Island. The plutonic rocks of diorite and granodiorite show high values of bulk <span class="hlt">magnetic</span> susceptibility of c.a. 0.01-0.4 SI, appearing to be the source of positive <span class="hlt">magnetic</span> <span class="hlt">anomaly</span>. We also revealed the preferred petrofabric lineation directions at the sites using anisotropy of <span class="hlt">magnetic</span> susceptibility (AMS). The AMS showed the plutonic rocks represent the vertical intrusion from the deep seated magma. Our optical microscope observation verified the maximum AMS orientation is parallel to the preferred alignment of framework-forming plagioclase, suggesting the alignment of euhedral magnetite grains along the long-axes of plagioclases. Our ship-borne and foot-borne surveys of geomagnetic filed <span class="hlt">anomaly</span> agree well with the distribution of the plutonic rocks, revealing the possible origin of surface <span class="hlt">magnetic</span> <span class="hlt">anomaly</span>. These suggests that the plutons in this area may be included ACG, and this <span class="hlt">magnetic</span> surveys is proposed to infer the availability to find out the presence of granitoid.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011NW.....98..575S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011NW.....98..575S"><span id="translatedtitle">Tracking pigeons in a <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> and in <span class="hlt">magnetically</span> "quiet" terrain</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schiffner, Ingo; Fuhrmann, Patrick; Wiltschko, Roswitha</p> <p>2011-07-01</p> <p>Pigeons were released at two sites of equal distance from the loft, one within a <span class="hlt">magnetic</span> <span class="hlt">anomaly</span>, the other in <span class="hlt">magnetically</span> quiet terrain, and their tracks were recorded with the help of GPS receivers. A comparison of the beginning of the tracks revealed striking differences: within the <span class="hlt">anomaly</span>, the initial phase lasted longer, and the distance flown was longer, with the pigeons' headings considerably farther from the home direction. During the following departure phase, the birds were well homeward oriented at the <span class="hlt">magnetically</span> quiet site, whereas they continued to be disoriented within the <span class="hlt">anomaly</span>. Comparing the tracks in the <span class="hlt">anomaly</span> with the underlying <span class="hlt">magnetic</span> contours shows considerable differences between individuals, without a common pattern emerging. The differences in <span class="hlt">magnetic</span> intensity along the pigeons' path do not differ from a random distribution of intensity differences around the release site, indicating that the <span class="hlt">magnetic</span> contours do not directly affect the pigeons' routes. Within the <span class="hlt">anomaly</span>, pigeons take longer until their flights are oriented, but 5 km from the release point, the birds, still within the <span class="hlt">anomaly</span>, are also significantly oriented in the home direction. These findings support the assumption that <span class="hlt">magnetically</span> anomalous conditions initially interfere with the pigeons' navigational processes, with birds showing rather individual responses in their attempts to overcome these problems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.usgs.gov/circ/1964/0489/report.pdf','USGSPUBS'); return false;" href="http://pubs.usgs.gov/circ/1964/0489/report.pdf"><span id="translatedtitle">A <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> of possible economic significance in southeastern Minnesota</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Zietz, Isidore</p> <p>1964-01-01</p> <p>An aeromagnetic survey in southeastern Minnesota by the U. S. Geological Survey in cooperation with the State of Minnesota has revealed a high-amplitude, linear, and narrow <span class="hlt">magnetic</span> feature that suggests a possible source of Precambrian iron-formation of economic value. For the past few years the U. S. Geological Survey has been conducting detailed geophysical studies of the midcontinent gravity <span class="hlt">anomaly</span>--a broad, high-amplitude feature that extends from Lake Superior through the States of Minnesota, Iowa, Nebraska, and part of Kansas. As part of this study an aeromagnetic survey of the southern part of the State was made in cooperation with the State of Minnesota during the summer of 1963, in which a linear high-amplitude <span class="hlt">anomaly</span> of the order of 4,000 gammas was discovered. Because of the high amplitude, the linearity, and the narrowness of the <span class="hlt">magnetic</span> feature, it is believed the source may be Precambrian iron-formation of possible economic value. The anomalous area is in Fillmore County, approximately between the towns of Lanesboro and Peterson in the extreme southeastern part of the State. (See figures 1 and 2.) At the site of the <span class="hlt">anomaly</span>, Cambrian sedimentary rocks occur in the valley of the Root River, and Ordovician rocks (nearly flat lying) mantle the upland areas. The uplands are largely covered by glacial deposits, which are relatively thin (Paul K. Sims, written communication, 1964). Depths to the Precambrian are estimated to range from 500 feet to 1,000 feet below the surface. The aeromagnetic map shown in figure 2 was compiled from continuous <span class="hlt">magnetic</span> profiles made along east-west flight lines 1,000 feet above ground, and spaced approximately 1 mile apart. Contour intervals of 20, 100, and 500 gammas were used depending on the intensity. The instrument for the survey was a flux-gate type magnetometer (AN/ASQ-3A) which measures total-field variations. The contour map displays variations in <span class="hlt">magnetic</span> pattern which are typical of shallow Precambrian rocks. <span class="hlt">Anomalies</span> of the order of 1,000 gammas are shown along the east and west edges of the map. The outstanding feature is the previously mentioned linear positive <span class="hlt">anomaly</span> that trends northeast and reaches a peak of 3,960 gammas. The positive <span class="hlt">anomaly</span> is contoured from data on four consecutive profiles, but only two show high amplitudes. The high-amplitude <span class="hlt">anomalies</span> along traverses 1 and 2 are shown in figure 3. Depth calculations suggest that the source of the <span class="hlt">anomaly</span> lies about 1,000 feet below the surface. Assuming a dikelike source and <span class="hlt">magnetization</span> resulting entirely from induction in the earth's field, several calculations were made in an attempt to fit the <span class="hlt">magnetic</span> profile taken along the line AA' (see figs. 2 and 4), considered to be a typical cross-section of the <span class="hlt">magnetic</span> <span class="hlt">anomaly</span>. Comparisons are shown between observed and computed profiles. The fixed parameters used were (a) distance from detector to source of 2,000 ft; width of dike of 5,000 ft; dip of dike of 75?, 90?, 105? , and 120? , as shown. The best fit occurs when the dike is vertical or dips 75? to the southwest. For these cases, the susceptibility, k, is computed to be 0.016 c.g.s, units, and is comparable to k = 0.02+ calculated by Bath (1962) for the relatively unmetamorphosed iron-formation of the Main Megabi district in Minnesota where the induced <span class="hlt">magnetization</span> was most likely the dominant <span class="hlt">magnetization</span>. If the dominant <span class="hlt">magnetization</span> for the <span class="hlt">anomaly</span> in Fillmore County were remanent rather than induced, the economic importance of the <span class="hlt">anomaly</span> would be greatly reduced. This <span class="hlt">anomaly</span> seems sufficiently promising to warrant further geologic and geophysical investigation. Detailed ground <span class="hlt">magnetic</span> and electrical studies would be useful to delineate the feature. In the final analysis, however, the presence of iron-formation can be determined only by the drill.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMGP11A..03H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMGP11A..03H"><span id="translatedtitle">Deep-sea Vector <span class="hlt">Magnetic</span> <span class="hlt">Anomalies</span> over the Bayonnaise Knoll Caldera (Izu-Ogasawara Arc) (Invited)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Honsho, C.; Ura, T.; Kim, K.</p> <p>2013-12-01</p> <p>The Bayonnaise Knoll caldera is located on the eastern margin of the backarc rift zone of the Izu-Ogasawara island arc. The caldera rim is ~3 km in diameter and 100-200 m high from the caldera floor 840-920 m deep. A large active hydrothermal field associated with sulfide deposit, called the Hakurei site, has been found at the foot of the southeastern caldera wall. We conducted deep-sea <span class="hlt">magnetic</span> measurements using autonomous underwater vehicles to map ~75 % of an area 3 km by 4 km in the caldera. The <span class="hlt">magnetic</span> vector field data were collected at 40-150 m altitude along the survey lines spaced 80-200 m apart. We improved the conventional correction method applied for removing the effect of vehicle <span class="hlt">magnetization</span>, which greatly enhanced the precision of the resulting vector <span class="hlt">anomalies</span> and allowed us to use the vector <span class="hlt">anomaly</span> instead of the total intensity <span class="hlt">anomaly</span> for inversion analysis. The <span class="hlt">magnetization</span> distribution obtained using the vector <span class="hlt">anomaly</span> was significantly different from the one obtained using the total intensity <span class="hlt">anomaly</span>, especially in areas where the survey tracks were widely spaced. The aliasing effect appears in areas of sparse data distribution, and the <span class="hlt">magnetic</span> field is more correctly calculated from the vector <span class="hlt">anomaly</span> than the total intensity <span class="hlt">anomaly</span>. The <span class="hlt">magnetization</span> distribution in the caldera has two major features: a ~1.5-km wide belt of high <span class="hlt">magnetization</span>, trending NNW-SSE through the caldera, and a clear low <span class="hlt">magnetization</span> zone, ~300 m x ~500 m wide, extending over the Hakurei site. The high <span class="hlt">magnetization</span> belt is considered to reflect basaltic volcanism associated with the backarc rifting that occurred after the formation of the Bayonnaise Knoll. The low <span class="hlt">magnetization</span> zone is interpreted as the alteration zone resulting from the hydrothermal activity. Several zones of localized high <span class="hlt">magnetization</span> are recognized within the high <span class="hlt">magnetization</span> belt, some of them in the caldera wall adjacent to the low <span class="hlt">magnetization</span> zone of the Hakurei site. We speculate that intensive magma intrusion occurred beneath the caldera wall and has provided the heat to generate hydrothermal fluid, which has been spouting out through the caldera wall faults. The surface expression of the vent field extends beyond the alteration zone inferred from the <span class="hlt">magnetization</span> distribution, <span class="hlt">spreading</span> upwards in the caldera wall. High-resolution topography around the Hakurei site indicates that the hydrothermal vents are generally distributed over a landform of slope failure. These observations would imply that hydrothermal fluid rising up in the up-flow zone moves laterally as well when it comes near the seafloor, probably along numerous fractures and fissures in the caldera wall. The distribution of pre-existing faults and fractures may rather control the fluid flow pathways in the shallow part and condition the surface extent of the vent field.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/17816737','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/17816737"><span id="translatedtitle">The moon: sources of the crustal <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hood, L L; Coleman, P J; Wilhelms, D E</p> <p>1979-04-01</p> <p>Previously unmapped Apollo 16 subsatellite magnetometer data collected at low altitudes over the lunar near side are presented. Medium-amplitude <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> exist over the Fra Mauro and Cayley Formations (primary and secondary basin ejecta emplaced 3.8 to 4.0 billion years ago) but are nearly absent over the maria and over the craters Copernicus, Kepler, and Reiner and their encircling ejecta mantles. The largest observed <span class="hlt">anomaly</span> (radial component approximately 21 gammas at an altitude of 20 kilometers) is exactly correlated with a conspicuous light-colored deposit on western Oceanus Procellarum known as Reiner gamma. Assuming that the Reiner gamma deposit is the source body and estimating its maximum average thickness as 10 meters, a minimum mean <span class="hlt">magnetization</span> level of 5.2 +/- 2.4 x 10(-2) electromagnetic units per gram, or approximately 500 times the stable <span class="hlt">magnetization</span> component of the most <span class="hlt">magnetic</span> returned sample, is calculated. An age for its emplacement of </= 2.9 billion years is inferred from photogeologic evidence, implying that <span class="hlt">magnetization</span> of lunar crustal materials must have continued for a period exceeding 1 billion years. PMID:17816737</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/864919','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/864919"><span id="translatedtitle">Apparatus for detecting a <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> contiguous to remote location by squid gradiometer and magnetometer systems</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Overton, Jr., William C.; Steyert, Jr., William A.</p> <p>1984-01-01</p> <p>A superconducting quantum interference device (SQUID) <span class="hlt">magnetic</span> detection apparatus detects <span class="hlt">magnetic</span> fields, signals, and <span class="hlt">anomalies</span> at remote locations. Two remotely rotatable SQUID gradiometers may be housed in a cryogenic environment to search for and locate unambiguously <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>. The SQUID <span class="hlt">magnetic</span> detection apparatus can be used to determine the azimuth of a hydrofracture by first flooding the hydrofracture with a ferrofluid to create an artificial <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> therein.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19990103130','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19990103130"><span id="translatedtitle">Thermal Sensitivity of MD Hematite: Implication for <span class="hlt">Magnetic</span> <span class="hlt">Anomalies</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kletetschka, Gunther; Wasilewski, Peter J.; Taylor, Patrick T.</p> <p>1999-01-01</p> <p><span class="hlt">Magnetic</span> remanence of crustal rocks can reside in three common rock-forming <span class="hlt">magnetic</span> minerals: magnetite, pyrrhotite, and hematite. Thermoremanent <span class="hlt">magnetization</span> (TRM) of magnetite and pyrrhotite is carried mostly by single domain (SD) grains. The TRM of hematite grains, however, is carried mostly by multidomain (NM) grains. This characteristic is illustrated by TRM acquisition curves for hematite of variable grainsizes. The transition between truly NM behavior and tendency towards SD behavior his been established between hematite grainsizes of 0. 1 and 0.05 mm. Coarse grainsize of lower crustal rocks and the large sensitivity of MD hematite grains to acquire TRM indicates that hematite could be a significant contributor to long-wavelength <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20000110488&hterms=PYRRHOTITE&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DPYRRHOTITE','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20000110488&hterms=PYRRHOTITE&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DPYRRHOTITE"><span id="translatedtitle">Petrological Explanations for the <span class="hlt">Magnetic</span> <span class="hlt">Anomalies</span> Detected on Mars</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Weitz, C. M.; Rutherford, M. J.</p> <p>1999-01-01</p> <p>The discovery of crustal <span class="hlt">magnetization</span> in some locations on Mars, particularly the southern highlands, has major implications for the early evolution of Mars. The east-west-trending linear features in the southern highlands with alternating polarity may be the result of an early seafloor <span class="hlt">spreading</span> process similar to that seen on Earth today. The larger <span class="hlt">magnetization</span> of the martian crust compared to the Earth can be attributed to its higher Fe content and the proposed minerals associated with this <span class="hlt">magnetization</span> are multidomain hematite and pyrrhotite. In this study, we discuss the petrological evolution of basalts on Earth and Mars and suggest processes that may enhance crystallization of <span class="hlt">magnetic</span> minerals in the martian rocks, thereby accounting for their intense <span class="hlt">magnetic</span> properties.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li class="active"><span>5</span></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_5 --> <div id="page_6" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li class="active"><span>6</span></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="101"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19870007985','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19870007985"><span id="translatedtitle">Improving the geological interpretation of <span class="hlt">magnetic</span> and gravity satellite <span class="hlt">anomalies</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hinze, William J.; Braile, Lawrence W.; Vonfrese, Ralph R. B.</p> <p>1987-01-01</p> <p>Quantitative analysis of the geologic component of observed satellite <span class="hlt">magnetic</span> and gravity fields requires accurate isolation of the geologic component of the observations, theoretically sound and viable inversion techniques, and integration of collateral, constraining geologic and geophysical data. A number of significant contributions were made which make quantitative analysis more accurate. These include procedures for: screening and processing orbital data for lithospheric signals based on signal repeatability and wavelength analysis; producing accurate gridded <span class="hlt">anomaly</span> values at constant elevations from the orbital data by three-dimensional least squares collocation; increasing the stability of equivalent point source inversion and criteria for the selection of the optimum damping parameter; enhancing inversion techniques through an iterative procedure based on the superposition theorem of potential fields; and modeling efficiently regional-scale lithospheric sources of satellite <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>. In addition, these techniques were utilized to investigate regional <span class="hlt">anomaly</span> sources of North and South America and India and to provide constraints to continental reconstruction. Since the inception of this research study, eleven papers were presented with associated published abstracts, three theses were completed, four papers were published or accepted for publication, and an additional manuscript was submitted for publication.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20120011787&hterms=magnetic+generator&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dmagnetic%2Bgenerator','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20120011787&hterms=magnetic+generator&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dmagnetic%2Bgenerator"><span id="translatedtitle">Numerical Simulations on Origin of Galilean Moons' <span class="hlt">Magnetic</span> <span class="hlt">Anomalies</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Jiao, LiQuo; Kuang, WeiJia; Ma, ShiZhuang</p> <p>2011-01-01</p> <p>Galileo mission detected the <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> originated from Galilean moons. These <span class="hlt">anomalies</span> are likely generated in the moons interiors, under the influence of a strong ambient Jovian field. Among various possible generation mechanisms of the <span class="hlt">anomalies</span>, we focus on magneto-convection and dynamos in the interiors via numerical simulation. To mimic the electromagnetic environment of the moons, we introduce in our numerical model an external uniform <span class="hlt">magnetic</span> field B(sub 0) with a fixed orientation but varying field strength. Our results show that a finite B(sub 0) can substantially alter the dynamo processes inside the core. When the ambient field strength B(sub 0) increases to approximately 40% of the field generated by the pure dynamo action, the convective state in the core changes significantly: the convective flow decreases by 80% in magnitude, but the differential rotation becomes stronger in much of the fluid layer, leading to a stronger field generated in the core. The field morphologies inside the core tend to align with the ambient field, while the flow patterns show the symmetry-breaking effect under the influence of B(sub 0). Furthermore, the generated field tends to be temporally more stable.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..1214689L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..1214689L"><span id="translatedtitle">The Russian contribution in WDMAM-2011 <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> and <span class="hlt">anomalies</span> of satellite Champ</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Livinova, Tamara; Glebovsky, Vladimir</p> <p>2010-05-01</p> <p>In VSEGEI is created the renovated digital cartographical model of an anomalous <span class="hlt">magnetic</span> field (AMF) of territory of Russia and adjacent aquatory of scale 1:2 500000 on the basis of the available base summary digital materials prepared at various times by two organizations: VSEGEI and VNIIOkeangeologia. For this purpose uniform technological rules which have provided satisfactory synthesis of digital data files of an anomalous <span class="hlt">magnetic</span> field in scale 1:2 500000 have been developed and realized. As a result of processing digital data file AMF the divergences reached 200 нТл, have been eliminated. For inclusion in WDMAM-2011 the Russian side the digital model counted on height 1 km on a grid 5х5км is offered. Anomalous values are designed from normal field VSEGEI of an epoch of 1965. The <span class="hlt">magnetic</span> grid (5x5 km) within the Russian continental shelf compiled in VNIIOkeangeologia was leveled, adjusted and merged with those created in VSEGEI on shore of Russian Federation. Data processing is made by software Geosoft. Russian <span class="hlt">magnetic</span> database in the Arctic Ocean was created as a result of adjusting of all historical and recent <span class="hlt">magnetic</span> data sets, collected several organizations during the period about 40 years. Within the deep part of the Arctic Ocean this information was leveled, adjusted and combined with all available US <span class="hlt">magnetic</span> data sets under cooperative project between and US Naval Research Laboratory. A result of this compilation is presented by grid of <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> (5x5 km) that was used in the CAMP-GM project.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PApGe.173.1733S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PApGe.173.1733S"><span id="translatedtitle">Interpretation of <span class="hlt">Magnetic</span> Phase <span class="hlt">Anomalies</span> over 2D Tabular Bodies</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Subrahmanyam, M.</p> <p>2016-05-01</p> <p>In this study, phase angle (inverse tangent of the ratio of the horizontal to vertical gradients of <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>) profile over two-dimensional tabular bodies has been subjected to detailed analysis for determining the source parameters. Distances between certain characteristic positions on this phase curve are related to the parameters of two-dimensional tabular <span class="hlt">magnetic</span> sources. In this paper, I have derived the mathematical expressions for these relations. It has been demonstrated here that for locating the origin of the 2D tabular source, knowledge on the type of the model (contact, sheet, dyke, and fault) is not necessary. A procedure is evolved to determine the location, depth, width and <span class="hlt">magnetization</span> angle of the 2D sources from the mathematical expressions. The method is tested on real field data. The effect of the overlapping bodies is also discussed with two synthetic examples. The interpretation technique is developed for contact, sheet, dike and inclined fault bodies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20030025336&hterms=RAE&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DRAE','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20030025336&hterms=RAE&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DRAE"><span id="translatedtitle">Utility of Satellite <span class="hlt">Magnetic</span> Observations for Estimating Near-Surface <span class="hlt">Magnetic</span> <span class="hlt">Anomalies</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kim, Hyung Rae; vonFrese, Ralph R. B.; Taylor, Patrick T.; Kim, Jeong Woo; Park, Chan Hong</p> <p>2003-01-01</p> <p>Regional to continental scale <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> maps are becoming increasingly available from airborne, shipborne, and terrestrial surveys. Satellite data are commonly considered to fill the coverage gaps in regional compilations of these near-surface surveys. For the near-surface Antarctic <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> map being produced by the Antarctic Digital <span class="hlt">Magnetic</span> <span class="hlt">Anomaly</span> Project (ADMAP), we show that near-surface <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> estimation is greatly enhanced by the joint inversion of the near-surface data with the satellite observations relative to the conventional technique such as minimum curvature. Orsted observations are especially advantageous relative to the Magsat data that have order-of-magnitude greater measurement errors, albeit at much lower orbital altitudes. CHAMP is observing the geomagnetic field with the same measurement accuracy as the Orsted mission, but at the lower orbital altitudes covered by Magsat. Hence, additional significant improvement in predicting near-surface <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> can result as these CHAMP data are available. Our analysis also suggests that considerable new insights on the <span class="hlt">magnetic</span> properties of the lithosphere may be revealed by a further order-of-magnitude improvement in the accuracy of the magnetometer measurements at minimum orbital altitude.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002EGSGA..27.2646S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002EGSGA..27.2646S"><span id="translatedtitle">The Stand Locations of Ancient People Depending On The Intensity of Local <span class="hlt">Magnetic</span> <span class="hlt">Anomalies</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shatokhin, I. T.; Khramov, A. V.; Shumilov, O. I.; Kasatkina, E. A.; Raspopov, O. M.</p> <p></p> <p>For analysis 235 ancient people stands in the region of Kursk <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> (one of the strongest <span class="hlt">anomaly</span> all over the world) were chosen. All stands were dated by radiocarbon method and are placed in the State List of Archaeological Monuments of Belgorod Region. The oldest stands were radiocarbon dated to 70,000-50,000 years before present (kyr BP). All stands are located along the 300 km valley of Oskol river, having got a homogeneous climatic conditions. At the half of the valley the intensity of local <span class="hlt">magnetic</span> field is rather low (0-1000 nT), so the region should be considered as the most comfort area for human occupation. The distribution of human occupation at this site looks as follows: 100% at 50-10 kyr BP, 94% at 6-4 kyr BP, 87% at 4-2 kyr BP, 83% at 3-2 kyr BP and 64% at 2-1 kyr BP. At ancient time humans preferred to occupy the sites with low <span class="hlt">magnetic</span> field intensity. The <span class="hlt">spreading</span> of human occupation outside of the comfort zone (more than 34%) began at Iron Age (2-1 kyr BP). Thus it may be concluded that in Palaeolithic age (50-10 kyr BP) humans avoided the area with enhanced level of local <span class="hlt">magnetic</span> field. This seems to be connected to bad influence of the factor on human health, lower level of orientation on the surface, may be to different plant distribution features, and state of ancient people anxiety. The <span class="hlt">spreading</span> of human occupation out of the comfort zone at rather recent time seems to be caused by social-economic activity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19850023274&hterms=Map+drawing&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DMap%2Bdrawing','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19850023274&hterms=Map+drawing&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DMap%2Bdrawing"><span id="translatedtitle">MAGSAT satellite <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> map over South America</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ridgway, J. R.</p> <p>1985-01-01</p> <p>A scalar <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> map was prepared for South America and adjacent marine areas directly from original MAGSAT orbits. Special problems associated with the separation of external field and crustal <span class="hlt">anomalies</span>, and the reduction of data to a common altitude are addressed. External fields are manifested in a long-wavelength ring current effect, a medium-wavelength equatorial electrojet, and short-wavelength noise. The noise is reduced by selecting profiles from quiet periods (Kp or = 3), and the effect of the electrojet is minimized by drawing the data set from dawn profiles only. The ring current is corrected through the use of a standard equation, augmented by further digital band-pass filtering. Profiles thus filtered differ primarily in amplitude due solely to satellite altitude differences. These differences are normalized by an inversion of the profile data onto a grid of equivalent point dipoles, and recalculated at an altitude of 350 km. The low altitudes in the study area cause instability in the inversion, necessitating separate inversions of several sub-areas which are subsequently merged. Crustal <span class="hlt">anomalies</span> reduced-to-the-pole exhibit marked correlations to known tectonic features.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.T42B..02T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.T42B..02T"><span id="translatedtitle">The last frontier? High-resolution, near-bottom measurements of the Hawaiian Jurassic <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> sequence</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tivey, M.; Tominaga, M.; Sager, W. W.</p> <p>2012-12-01</p> <p>The Jurassic sequence of marine <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> i.e. older than M29 remain the last part of the marine <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> sequence of the geomagnetic polarity timescale (GPTS) that can be gleaned from the ocean crustal record. While Jurassic crust is present in several areas of the world's ocean basins, the oldest and arguably best preserved sequence is in the western Pacific where three lineations sets (Japanese, Hawaiian and Phoenix) converge on the oldest remaining ocean crust on the planet (i.e. crust that has not been subducted). The <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> in these 3 lineation sets are marked by low amplitude, relatively indistinct <span class="hlt">anomalies</span> (tiny wiggles) that collectively have been called the Jurassic quiet Zone (JQZ). Over the past 20 years we have been working on resolving the character and origin of these <span class="hlt">anomalies</span> with various technologies to improve our resolution of this period. Following an aeromagnetic survey that revealed the possible presence of lineated <span class="hlt">anomalies</span> older than M29 in the Japanese lineations, we conducted a deeptow magnetometer survey of the Japanese sequence in 1992. In 2002/03 we extended and confirmed this deeptow record with a deeptowed sidescan and magnetometer survey of the Japanese lineation sequence by tying in ODP Hole 801C and extending the <span class="hlt">anomaly</span> sequence between M29 and M44. These surveys reveal remarkably fast reversals that are lineated and decrease in intensity back in time until M38, prior to which the sequence becomes somewhat confused (the LAZ or low amplitude zone) before recovering in both amplitude and lineated character around Hole 801C (M42). These results are partially supported by recently reported terrestrial magnetostratigraphy records that show the existence of reversals back to M38. A Jurassic GPTS was constructed from this Japanese <span class="hlt">anomaly</span> sequence, but the overall global significance of the reversal sequence and systematic field intensity changes require confirmation from crustal records created at different <span class="hlt">spreading</span> centers. In 2011, we undertook the next generation of near-bottom <span class="hlt">magnetic</span> studies utilizing new autonomous underwater vehicle (AUV) technology (Sentry) and concurrent deeptow and seismic profiling surveys of the Hawaiian <span class="hlt">anomaly</span> sequence. Preliminary results show a similar <span class="hlt">anomaly</span> record to the Japanese sequence: an overall decrease in <span class="hlt">anomaly</span> amplitude from M19 to M38 and a period of low amplitude, which in turn is preceded by a return to stronger amplitude <span class="hlt">anomalies</span>. The <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> correlations between Hawaiian and Japanese sea-surface level profiles confirm the reversal record back in time, at least, to M38. At the mid-water and near-bottom AUV levels, the <span class="hlt">magnetic</span> data clearly show the short-wavelength <span class="hlt">anomaly</span> character of the M29-M38 sequence, indicating that the fast reversals observed in the Japanese lineations are also present in the Hawaiian lineation set. The strong similarity of overall <span class="hlt">anomaly</span> patterns between Japanese and Hawaiian sequences supports the preliminary conclusion that geomagnetic field behavior during the Jurassic was dynamic, with fast reversals and changing intensity, and certainly not "quiet". Finally, AUV surveys provide measurements of the marine <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> record whose resolution is limited only by the crustal recording process and crustal <span class="hlt">magnetic</span> architecture rather than spatial resolution.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007SPIE.6553E..0OK','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007SPIE.6553E..0OK"><span id="translatedtitle">Underwater <span class="hlt">magnetic</span> gradiometer for <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> detection, localization, and tracking</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kumar, S.; Sulzberger, G.; Bono, J.; Skvoretz, D.; Allen, G. I.; Clem, T. R.; Ebbert, M.; Bennett, S. L.; Ostrom, R. K.; Tzouris, A.</p> <p>2007-04-01</p> <p>GE Security and the Naval Surface Warfare Center, Panama City (NSWC-PC) have collaborated to develop a <span class="hlt">magnetic</span> gradiometer, called the Real-time Tracking Gradiometer or RTG that is mounted inside an unmanned underwater vehicle (UUV). The RTG is part of a buried mine hunting platform being developed by the United States Navy. The RTG has been successfully used to make test runs on mine-like targets buried off the coast of Florida. We will present a general description of the system and latest results describing system performance. This system can be also potentially used for other applications including those in the area of Homeland Security.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016Icar..266..261P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016Icar..266..261P"><span id="translatedtitle">Solar wind interaction with the Reiner Gamma crustal <span class="hlt">magnetic</span> <span class="hlt">anomaly</span>: Connecting source <span class="hlt">magnetization</span> to surface weathering</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Poppe, Andrew R.; Fatemi, Shahab; Garrick-Bethell, Ian; Hemingway, Doug; Holmström, Mats</p> <p>2016-03-01</p> <p>Remanent <span class="hlt">magnetization</span> has long been known to exist in the lunar crust, yet both the detailed topology and ultimate origin(s) of these fields remains uncertain. Some crustal <span class="hlt">magnetic</span> fields coincide with surface albedo <span class="hlt">anomalies</span>, known as lunar swirls, which are thought to be formed by differential surface weathering of the regolith underlying crustal fields due to deflection of incident solar wind protons. Here, we present results from a three-dimensional, self-consistent, plasma hybrid model of the solar wind interaction with two different possible source <span class="hlt">magnetizations</span> for the Reiner Gamma <span class="hlt">anomaly</span>. We characterize the plasma interaction with these fields and the resulting spatial distribution of charged-particle weathering of the surface and compare these results to optical albedo measurements of Reiner Gamma. The model results constrain the proposed source <span class="hlt">magnetizations</span> for Reiner Gamma and suggest that vertical crustal <span class="hlt">magnetic</span> fields are required to produce the observed "dark lanes."</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22218401','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22218401"><span id="translatedtitle">Current disruption and its <span class="hlt">spreading</span> in collisionless <span class="hlt">magnetic</span> reconnection</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Jain, Neeraj; Büchner, Jörg; Ji, Hantao</p> <p>2013-11-15</p> <p>Recent <span class="hlt">magnetic</span> reconnection experiments (MRX) [Dorfman et al., Geophys. Res. Lett. 40, 233 (2013)] have disclosed current disruption in the absence of an externally imposed guide field. During current disruption in MRX, both the current density and the total observed out-of-reconnection-plane current drop simultaneous with a rise in out-of-reconnection-plane electric field. Here, we show that current disruption is an intrinsic property of the dynamic formation of an X-point configuration of <span class="hlt">magnetic</span> field in <span class="hlt">magnetic</span> reconnection, independent of the model used for plasma description and of the dimensionality (2D or 3D) of reconnection. An analytic expression for the current drop is derived from Ampere's Law. Its predictions are verified by 2D and 3D electron-magnetohydrodynamic (EMHD) simulations. Three dimensional EMHD simulations show that the current disruption due to localized <span class="hlt">magnetic</span> reconnection <span class="hlt">spreads</span> along the direction of the electron drift velocity with a speed which depends on the wave number of the perturbation. The implications of these results for MRX are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMGP11A..07F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMGP11A..07F"><span id="translatedtitle">Absolute <span class="hlt">Magnetization</span> Distribution on Back-arc <span class="hlt">Spreading</span> Axis Hosting Hydrothermal Vents; Insight from Shinkai 6500 <span class="hlt">Magnetic</span> Survey</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fujii, M.; Okino, K.; Honsho, C.; Mochizuki, N.; Szitkar, F.; Dyment, J.</p> <p>2013-12-01</p> <p>Near-bottom <span class="hlt">magnetic</span> profiling using submersible, deep-tow, Remotely Operated Vehicle (ROV) and Autonomous Underwater Vehicle (AUV) make possible to conduct high-resolution surveys and depict detailed <span class="hlt">magnetic</span> features reflecting, for instance, the presence of fresh lavas or hydrothermal alteration, or geomagnetic paleo-intensity variations. We conducted near-bottom three component <span class="hlt">magnetic</span> measurements onboard submersible Shinkai 6500 in the Southern Mariana Trough, where five active hydrothermal vent fields (Snail, Yamanaka, Archean, Pica, and Urashima sites) have been found in both on- and off-axis areas of the active back-arc <span class="hlt">spreading</span> center, to detect signals from hydrothermally altered rock and to distinguish old and new submarine lava flows. Fourteen dives were carried out at an altitude of 1-40 m during the R/V Yokosuka YK10-10 and YK10-11 cruises in 2010. We carefully corrected the effect of the induced and permanent <span class="hlt">magnetizations</span> of the submersible by applying the correction method for the shipboard three-component magnetometer measurement modified for deep-sea measurement, and subtracted the IGRF values from the corrected data to obtain geomagnetic vector <span class="hlt">anomalies</span> along the dive tracks. We then calculated the synthetic <span class="hlt">magnetic</span> vector field produced by seafloor, assumed to be uniformly <span class="hlt">magnetized</span>, using three dimensional forward modeling. Finally, values of the absolute <span class="hlt">magnetizations</span> were estimated by using a linear transfer function in the Fourier domain from the observed and synthetic <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>. The distribution of estimated absolute <span class="hlt">magnetization</span> generally shows low values around the five hydrothermal vent sites. This result is consistent with the equivalent <span class="hlt">magnetization</span> distribution obtained from previous AUV survey data. The areas of low <span class="hlt">magnetization</span> are also consistent with hydrothermal deposits identified in video records. These results suggest that low <span class="hlt">magnetic</span> signals are due to hydrothermal alteration zones where host rocks are demagnetized by hydrothermal circulation. The low <span class="hlt">magnetization</span> zones around the off-axis vent sites are about ten times wider than those surrounding the on-axis sites, possibly reflecting the longer duration of hydrothermal circulation at these sites. Another interesting result is that the absolute <span class="hlt">magnetization</span> shows extremely high intensities (>80 A/m) at the neo volcanic zones (NVZ) and relatively low intensities (<10 A/m) two to five kilometers away from the NVZ. These variations are quite consistent with those of the Natural Remanent <span class="hlt">Magnetization</span> measured on basalt samples, suggesting that the low-temperature oxidation of host rock due to the reaction with seawater has completed within a few kilometers distance from the <span class="hlt">spreading</span> axis. We conclude that the <span class="hlt">magnetization</span> of the uppermost oceanic crust decreases with age due to the combination of the both hydrothermal rapid alteration and the low-temperature gradual alteration processes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19820047262&hterms=possibility&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dpossibility','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19820047262&hterms=possibility&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dpossibility"><span id="translatedtitle">On the possibility of detecting large-scale crustal remanent <span class="hlt">magnetization</span> with Magsat vector <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> data</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Galliher, S. C.; Mayhew, M. A.</p> <p>1982-01-01</p> <p><span class="hlt">Magnetic</span> <span class="hlt">anomaly</span> component data measured by Magsat is compared with synthetic <span class="hlt">anomaly</span> component fields arising from an equivalent source dipole array at the earth's surface generated from total field <span class="hlt">anomaly</span> data alone. It is found that the synthetic components fit the component data regardless of the dipole orientation assigned to the equivalent sources and of the dipole spacing. Tentative conclusions are: (1) over the U.S., vector <span class="hlt">anomaly</span> fields can be determined to the accuracy of the measurements from the total field <span class="hlt">anomaly</span> data alone; and (2) the equivalent source technique is not useful for determining the direction of large-scale crustal <span class="hlt">magnetization</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JGRA..12010979J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JGRA..12010979J"><span id="translatedtitle">Simultaneous observations of F2 layer stratification and <span class="hlt">spread</span> F at postmidnight over a northern equatorial <span class="hlt">anomaly</span> region</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jiang, Chunhua; Yang, Guobin; Deng, Chi; Zhou, Chen; Zhu, Peng; Yokoyama, Tatsuhiro; Song, Huan; Lan, Ting; Ni, Binbin; Zhao, Zhengyu; Zhang, Yuannong</p> <p>2015-12-01</p> <p>Simultaneous observations of F2 layer stratification and <span class="hlt">spread</span> F at postmidnight (00:00 LT to 05:00 LT) were carried out on 22, 23, and 28 November 2013, using ionosondes distributed over a northern equatorial <span class="hlt">anomaly</span> region at three specific locations, i.e., Puer (PUR, 22.7°N, 101.05°E, dip latitude 12.9°N), Chiang Mai (CMU, 18.8°N, 98.9°E, dip latitude 9.04°N), and Chumphon (CPN, 10.7°N, 99.4°E, dip latitude 0.93°N). The results show that both the PUR and CMU stations observed the F2 layer stratification at postmidnight in the Northern Hemisphere, frequently accompanied with gravity waves (the periods~30-100 min). It is reported that F2 layer stratification at postmidnight can be observed in the Northern Hemisphere for the first time. It is suggested that the thermospheric neutral wind triggered by gravity waves strongly contribute to the altitude dependence of the combined vertical plasma velocity, which consequently poses significant impacts on the occurrence of the low-latitude F2 layer stratification at postmidnight. In addition, the <span class="hlt">spread</span> F other than F2 layer stratification was observed at the CPN station located at the geomagnetic equator, suggesting that smaller geomagnetic inclination tend to inhibit the postmidnight F2 layer stratification in the equatorial region. Furthermore, on 23 November 2013 a good correlation was identified between the F2 layer stratification at PUR and the <span class="hlt">spread</span> F at both CMU and CPN, possibly due to that the large-scale gravity waves originating at middle latitudes contribute to the nighttime <span class="hlt">spread</span> F observed in the low-latitude and equatorial regions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19820052288&hterms=Curie&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DCurie','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19820052288&hterms=Curie&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DCurie"><span id="translatedtitle">An equivalent layer <span class="hlt">magnetization</span> model for the United States derived from satellite altitude <span class="hlt">magnetic</span> <span class="hlt">anomalies</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mayhew, M. A.</p> <p>1982-01-01</p> <p>Long wavelength <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> measured by the Pogo series satellites at altitudes 400-700 km over the United States and adjacent areas are inverted to an equivalent layer <span class="hlt">magnetization</span> model based on an equal area dipole source array at the earth's surface. Minimum source spacing giving a stable solution and a physically meaningful <span class="hlt">magnetization</span> distribution is 300 km, and a scheme is presented for effectively sampling the distribution on a grid twice as fine. The model expresses lateral variation in the vertical integral of <span class="hlt">magnetization</span> and is a starting point for models of lateral variation in the form of the <span class="hlt">magnetization</span>-depth curve in the <span class="hlt">magnetic</span> crust. The <span class="hlt">magnetization</span> model contours correlate with large-scale tectonic features, and in the western part of the country, probably reflect Curie isotherm undulations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20040171248&hterms=RAE&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DRAE','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20040171248&hterms=RAE&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DRAE"><span id="translatedtitle">Estimating Antarctic Near-Surface <span class="hlt">Magnetic</span> <span class="hlt">Anomalies</span> from Oersted and CHAMP Satellite Magnetometer Observations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>vonFrese, Ralph R. B.; Kim, Hyung Rae; Gaya-Pique, Luis R.; Taylor, Patrick T.; Golynsky, Alexander V.; Kim, Jeong Woo</p> <p>2004-01-01</p> <p>Significant improvement in predicting near-surface <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> can result from the highly accurate <span class="hlt">magnetic</span> observations of the CHAMP satellite that is orbiting at about 400 km altitude. In general, regional <span class="hlt">magnetic</span> signals of the crust are strongly masked by the core field and its secular variations due to wavelength coupling in the spherical harmonic representation and thus are difficult to isolate in the satellite measurements. However, efforts to isolate the regional lithospheric from core field components can exploit the correlations between the CHAMP <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> and the pseudo <span class="hlt">magnetic</span> effects inferred from gravity-derived crustal thickness variations. In addition, we can use spectral correlation theory to filter the static lithospheric field components from the dynamic external field effects. Employing these procedures, we processed the CHAMP <span class="hlt">magnetic</span> conservations for an improved <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> map of the Antarctic crust. Relative to the much higher altitude Oersted and noisier Magsat observations, CHAMP <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> at 400 km altitude reveal new details on the effects of intra-crustal <span class="hlt">magnetic</span> features and crustal thickness variations of the Antarctic. Moreover, these results greatly facilitate predicting <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> in the regional coverage gaps of the ADMAP compilation of Antarctic <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> from shipborne, airborne and ground surveys. Our analysis suggests that considerable new insights on the <span class="hlt">magnetic</span> properties of the lithosphere may be revealed by a further order-of-magnitude improvement in the accuracy of the magnetometer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013PEPI..224...11O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013PEPI..224...11O"><span id="translatedtitle">Rock <span class="hlt">magnetic</span> investigation of possible sources of the Bangui <span class="hlt">magnetic</span> <span class="hlt">anomaly</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ouabego, M.; Quesnel, Y.; Rochette, P.; Demory, F.; Fozing, E. M.; Njanko, T.; Hippolyte, J.-C.; Affaton, P.</p> <p>2013-11-01</p> <p>The Bangui <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> (BMA) is the largest lithospheric <span class="hlt">magnetic</span> field <span class="hlt">anomaly</span> on Earth at low latitudes. Previous studies investigated its geological source using constraints from satellite and ground <span class="hlt">magnetic</span> field measurements, as well as from surface <span class="hlt">magnetic</span> susceptibility measurements on rocks from the Panafrican Mobile Belt Zone (PMBZ). Here we combine <span class="hlt">magnetic</span> field data modelling and rock <span class="hlt">magnetic</span> property measurements (susceptibility and natural remanent <span class="hlt">magnetization</span>, NRM) on many samples from this PMBZ and the surrounding formations. It reveals that NRM is a significant component of the total <span class="hlt">magnetization</span> (Mt) of the BMA source, which reaches 4.3 A/m with maximum thicknesses of 38 and 54 km beneath the western and eastern parts of the BMA. Only the isolated and relatively thin banded iron formations and some migmatites show such Mt values. Thus we suggest that the thick BMA source may be composed either by overlapped slices of such metamorphic rocks, or by an iron-rich mafic source, or by a combination of these two geological structures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMGP41C1130V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMGP41C1130V"><span id="translatedtitle">Paleomagnetic and rock <span class="hlt">magnetic</span> characterization of <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> in the Central Iberian Arc (Iberian Peninsula)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Villalain, J.; Ayarza, P.; Martinez-Catalan, J. R.; Álvarez-Lobato, F.; Gómez-Barreiro, J.; Suárez Barrios, M.; Torres-López, S.</p> <p>2013-12-01</p> <p>The Central Iberian Arc is one of the four oroclines delineated by the European Variscan Belt. It is located in NW and Central Iberia and characterized by a conspicuous <span class="hlt">magnetic</span> response. The most intense <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> within this arc is the so called Eastern Galicia <span class="hlt">Magnetic</span> <span class="hlt">Anomaly</span> (EGMA; Aller et al., 1994), located in the northern part of Spain and associated to the Lugo-Sanabria dome, an extensional structure in the inner part of arc. The aeromagnetic map of the Iberian Peninsula (Ardizone et al., 1989; Miranda et al., 1989) shows that the EGMA continues to Central Spain and turns back to the Atlantic Ocean, as a broad positive <span class="hlt">anomaly</span>, delineating a tight fold at the core of the Central Iberian Arc. The source of the EGMA seems to be magnetite-bearing migmatites and inhomogeneous granites formed during an extensive late Carboniferous thermal event triggered by Variscan crustal thickening. These rocks were modeled as a lens-shaped body up to 12 km thick with <span class="hlt">magnetic</span> susceptibility values between 0.02and 0.03 SI units, that underlie the whole dome extension and continues toward the west of it (Ayarza and Martínez Catalán, 2007). However, this body crops out only in the deepest and northernmost part of the dome, in the Xistral Tectonic Window, and there, only its upper part is accessible. Migmatites and granitoids are abundant along the rest of the <span class="hlt">anomaly</span>, but their <span class="hlt">magnetic</span> susceptibility is low. Thus, the source of the <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> should be buried there and its nature is unknown. Paleomagnetic and rock <span class="hlt">magnetic</span> studies in the outcropping rocks responsible for the EGMA have been carried out, adding new constraints to the origin of this <span class="hlt">anomaly</span>. Rock <span class="hlt">magnetic</span> analysis as progressive acquisition of IRM, hysteresis loops, thermomagnetic experiments and X-ray indicate that the ferromagnetic fraction is dominated by multidomain magnetite and titanohematite. It is remarkable the unusual high anisotropy of <span class="hlt">magnetic</span> susceptibility of these rocks, showing degree of anisotropy values 1.2<P<3. The observed <span class="hlt">magnetic</span> fabric shows Variscan affinity, related to an extensional ductile detachment that bounds the Lugo-Sanabria dome to the west. The paleomagnetic analysis consisting in thermal and alternating field demagnetization allows isolating a stable paleomagnetic component with high coercivity and maximum unblocking temperatures of about 630°C, that systematically shows reversed polarity. This component has been interpreted as a remagnetization because its mean direction match those of the Iberian Peninsula after anticlockwise rotation related to the opening of the Bay of Biscay during the Early Cretaceous. All these data must be included in the models in order to place new constraints on the origin, position, and shape of the source and to asses whether all the broad <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> at the core of the Central Iberian Arc has the same origin as the EGMA, or a deeper source contributes to it and to the rest of the <span class="hlt">anomaly</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014Icar..243...27C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014Icar..243...27C"><span id="translatedtitle">Surveying the South Pole-Aitken basin <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> for remnant impactor metallic iron</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cahill, Joshua T. S.; Hagerty, Justin J.; Lawrence, David J.; Klima, Rachel L.; Blewett, David T.</p> <p>2014-11-01</p> <p>The Moon has areas of <span class="hlt">magnetized</span> crust ("<span class="hlt">magnetic</span> <span class="hlt">anomalies</span>"), the origins of which are poorly constrained. A <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> near the northern rim of South Pole-Aitken (SPA) basin was recently postulated to originate from remnant metallic iron emplaced by the SPA basin-forming impactor. Here, we remotely examine the regolith of this SPA <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> with a combination of Clementine and Lunar Prospector derived iron maps for any evidence of enhanced metallic iron content. We find that these data sets do not definitively detect the hypothesized remnant metallic iron within the upper tens of centimeters of the lunar regolith.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70135283','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70135283"><span id="translatedtitle">Surveying the South Pole-Aitken basin <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> for remnant impactor metallic iron</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Cahill, Joshua T.S.; Hagerty, Justin J.; Lawrence, David M.; Klima, Rachel L.; Blewett, David T.</p> <p>2014-01-01</p> <p>The Moon has areas of <span class="hlt">magnetized</span> crust ("<span class="hlt">magnetic</span> <span class="hlt">anomalies</span>"), the origins of which are poorly constrained. A <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> near the northern rim of South Pole-Aitken (SPA) basin was recently postulated to originate from remnant metallic iron emplaced by the SPA basin-forming impactor. Here, we remotely examine the regolith of this SPA <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> with a combination of Clementine and Lunar Prospector derived iron maps for any evidence of enhanced metallic iron content. We find that these data sets do not definitively detect the hypothesized remnant metallic iron within the upper tens of centimeters of the lunar regolith.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li class="active"><span>6</span></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_6 --> <div id="page_7" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active"><span>7</span></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="121"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150022458','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150022458"><span id="translatedtitle">Determination Gradients of the Earth's <span class="hlt">Magnetic</span> Field from the Measurements of the Satellites and Inversion of the Kursk <span class="hlt">Magnetic</span> <span class="hlt">Anomaly</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Karoly, Kis; Taylor, Patrick T.; Geza, Wittmann</p> <p>2014-01-01</p> <p>We computed <span class="hlt">magnetic</span> field gradients at satellite altitude, over Europe with emphasis on the Kursk <span class="hlt">Magnetic</span> <span class="hlt">Anomaly</span> (KMA). They were calculated using the CHAMP satellite total <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>. Our computations were done to determine how the <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> data from the new ESA/Swarm satellites could be utilized to determine the structure of the <span class="hlt">magnetization</span> of the Earths crust, especially in the region of the KMA. Since the ten years of 2 CHAMP data could be used to simulate the Swarm data. An initial East <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> gradient map of Europe was computed and subsequently the North, East and Vertical <span class="hlt">magnetic</span> gradients for the KMA region were calculated. The vertical gradient of the KMA was determined using Hilbert transforms. Inversion of the total KMA was derived using Simplex and Simulated Annealing algorithms. Our resulting inversion depth model is a horizontal quadrangle with upper 300-329 km and lower 331-339 km boundaries.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.T43D2704F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.T43D2704F"><span id="translatedtitle"><span class="hlt">Magnetic</span> Structure of Backarc <span class="hlt">Spreading</span> Axis with Hydrothermal Vents; the Southern Mariana Trough</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fujii, M.; Okino, K.; Mochizuki, N.; Honsho, C.; Szitkar, F.; Dyment, J.; Nakamura, K.</p> <p>2012-12-01</p> <p>Seafloor hydrothermal systems are important in relation to global heat and chemical fluxes as well as habitat of microbial communities. The substantial variation of hydrothermal systems in various tectonic settings has important implications for the <span class="hlt">magnetic</span> structure of oceanic crust. It has been very difficult to detect the geophysical signature of hydrothermal systems from sea-surface data because the small scale of hydrothermal systems is below the limit of resolution. The advance of near-bottom survey methods using a submersible, deep-tow, ROV and AUV has made possible high-resolution geophysical mapping around hydrothermal areas. Near-bottom <span class="hlt">magnetic</span> surveys can provide direct information on the <span class="hlt">magnetization</span> of the shallower oceanic crust, implying hydrothermal alteration both in active and fossil vent sites. Near-bottom three component <span class="hlt">magnetic</span> measurements on submersible Shinkai 6500 were carried out at hydrothermal fields in the Southern Mariana Trough, a slow <span class="hlt">spreading</span> backarc basin. Fourteen dive surveys were conducted during cruises YK11-10 and YK10-11. We investigated the <span class="hlt">magnetic</span> structure of four hydrothermal systems located at on- and off-axis to clarify how the geophysical and geological setting controls the fluid circulation at small scale. Recent researches at slow <span class="hlt">spreading</span> ridges showed a relationship between crustal <span class="hlt">magnetic</span> structure and host rock around hydrothermal vents (e.g. Tivey and Dyment, 2010), but no observation at backarc <span class="hlt">spreading</span> axis has been reported so far. We carefully corrected the effects of induced and permanent <span class="hlt">magnetizations</span> of the submersible by applying the method of Isezaki [1986] with dumped least-square method (Honsho et al., 2009). After subtracting the IGRF from the corrected observed data, we obtained geomagnetic vector <span class="hlt">anomalies</span> in geographical coordinate. For three transects of the axis, we applied three methods; 2D inversion technique (Parker and Huestis, 1972), 2D forward modeling technique (Honsho et al, 2009) and 2D direct inversion technique (Hussenoeder et al., 1995). Transect 1 (T1) and transect 2 (T2) are parallel and very closely located, crossing the neo-volcanic zone near an on-axis hydrothermal site (Snail Site) at different altitude, 2m and 30m. Transect 3 (T3) also crosses a large on-axis volcanic mound on which another hydrothermal site (Yamanaka Site) is located. The equivalent <span class="hlt">magnetization</span> calculated on T1 and T2 are similar although their resolutions are different. The one along T3 shows high values around the large volcanic mound and an area of low <span class="hlt">magnetization</span> near a hydrothermal field recognized from high-resolution bathymetry (Yoshikawa et al., 2012). A similar reduction of <span class="hlt">magnetization</span> above hydrothermal fields was also reported in basalt-hosted sites along the Mid Atlantic Ridge. The detailed bathymetry (2m grid) collected by AUV Urashima in the study area allows us to investigate the effect of three dimensional structure. We estimate <span class="hlt">magnetization</span> using a new technique based on 3D forward modeling (Szitkar et al, this meeting). A preliminary result shows a similar but more detailed <span class="hlt">magnetic</span> structure around the Yamanaka Site compared to results of the 2D methods.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JGRB..120.2821F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JGRB..120.2821F"><span id="translatedtitle">High-resolution <span class="hlt">magnetic</span> signature of active hydrothermal systems in the back-arc <span class="hlt">spreading</span> region of the southern Mariana Trough</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fujii, Masakazu; Okino, Kyoko; Honsho, Chie; Dyment, Jerome; Szitkar, Florent; Mochizuki, Nobutatsu; Asada, Miho</p> <p>2015-05-01</p> <p>High-resolution vector <span class="hlt">magnetic</span> measurements were performed on five hydrothermal vent fields of the back-arc <span class="hlt">spreading</span> region of the southern Mariana Trough using Shinkai 6500, a deep-sea manned submersible. A new 3-D forward scheme was applied that exploits the surrounding bathymetry and varying altitudes of the submersible to estimate absolute crustal <span class="hlt">magnetization</span>. The results revealed that <span class="hlt">magnetic-anomaly</span>-derived absolute <span class="hlt">magnetizations</span> show a reasonable correlation with natural remanent <span class="hlt">magnetizations</span> of rock samples collected from the seafloor of the same region. The distribution of <span class="hlt">magnetic-anomaly</span>-derived absolute <span class="hlt">magnetization</span> suggests that all five andesite-hosted hydrothermal fields are associated with a lack of <span class="hlt">magnetization</span>, as is generally observed at basalt-hosted hydrothermal sites. Furthermore, both the Pika and Urashima sites were found to have their own distinct low-<span class="hlt">magnetization</span> zones, which could not be distinguished in <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> data collected at higher altitudes by autonomous underwater vehicle due to their limited extension. The spatial extent of the resulting low <span class="hlt">magnetization</span> is approximately 10 times wider at off-axis sites than at on-axis sites, possibly reflecting larger accumulations of nonmagnetic sulfides, stockwork zones, and/or alteration zones at the off-axis sites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014Tectp.636..228S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014Tectp.636..228S"><span id="translatedtitle">An integrated geophysical study of the Beattie <span class="hlt">Magnetic</span> <span class="hlt">Anomaly</span>, South Africa</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Scheiber-Enslin, Stephanie; Ebbing, Jörg; Webb, Susan J.</p> <p>2014-12-01</p> <p>The source of the Beattie <span class="hlt">Magnetic</span> <span class="hlt">Anomaly</span> (BMA) still remains unclear, with several competing hypotheses. Here we add a piece to the puzzle by investigating available potential field data over the <span class="hlt">anomaly</span>. Filtered <span class="hlt">magnetic</span> data show the BMA as part of a group of linear <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>. As the linear <span class="hlt">anomaly</span> north of the BMA is associated with exposed supracrustals, migmatites and shear zones within the Natal thrust terranes we assume a similar source for the BMA. This source geometry, constrained by seismic and MT data, fits potential field data over the BMA and other <span class="hlt">magnetic</span> linear <span class="hlt">anomalies</span> in the south-central and south-western Karoo. In these models the bodies deepen from ~ 5 km towards the south, with horizontal extents of ~ 20-60 km and vertical extents of ~ 10-15 km. Densities range from 2800 to 2940 kg/m3 and <span class="hlt">magnetic</span> susceptibilities from 10 to 100 × 10- 3 SI. These <span class="hlt">magnetic</span> susceptibilities are higher than field values from supracrustal rocks (10-60 × 10- 3 SI) but could be due to the fact that no remanent magnetisation was included in the model. The lithologies associated with the different linear <span class="hlt">anomalies</span> vary as is evident from varying <span class="hlt">anomaly</span> amplitudes. The strong signal of the BMA is linked to high <span class="hlt">magnetic</span> susceptibility granulite facies supracrustals (~ 10-50 × 10- 3 SI) as seen in the Antarctic, where the mobile belt continued during Gondwana times.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19950057678&hterms=non+natural&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dnon%2Bnatural','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19950057678&hterms=non+natural&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dnon%2Bnatural"><span id="translatedtitle">Contributions of cretaceus quiet zone natural remanent <span class="hlt">magnetization</span> to Magsat <span class="hlt">anomalies</span> in the Southwest Indian Ocean</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Fullerton, Lawrence G.; Frey, Herbert V.; Roark, James H.; Thomas, Herman H.</p> <p>1994-01-01</p> <p>The Magsat <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> over the Southwest Indian Ocean are modeled using a combination of induced plus viscous remanent <span class="hlt">magnetization</span> (IM/VRM) and natural remanent <span class="hlt">magnetization</span> (NRM). Two broad, roughly parallel, SW to NE trending triple-peaked positive <span class="hlt">anomalies</span> dominate the region, one lying south of Africa and the other north of Antarctica. Although these <span class="hlt">anomaly</span> peaks generally correspond with the Agulhas Plateau/Maud Rise, Mozambique Plateau/Astrid Ridge, and Madagascar Ridge/Conrad Rise conjugate pairs, the IM/VRM contribution from structural characteristics (i.e., crustal thickness) accounts for only about 20% of the <span class="hlt">anomaly</span> amplitudes. A spatially variable but observationally constrained NRM contribution in Cretaceous Quiet Zone (KQZ) crust is required to account for the location, shape, and amplitude contrast of these <span class="hlt">anomalies</span>. Many crustal features in the Southwest Indian Ocean near Antarctica have little geophysical data to constrain their structure but do hagve tectonic conjugates near Africa for which much more geophysical data are generally available. Using geophysical and geological constraints from one member to model the <span class="hlt">magnetization</span> structure of its conjugate reproduces the observed Magsat reduced-to-pole <span class="hlt">anomalies</span> over both structures very well. This suggests that no significant alteration in their <span class="hlt">magnetization</span> structure has occurred since the features split. Models of these conjugate structures show that IM/VRM reproduces the Magsat <span class="hlt">anomalies</span> associated with non-KQZ crust but that both IM/VRM and a dominant NRM component are required to explain the <span class="hlt">anomalies</span> associated with KQZ crust.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AIPA....6e6603N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AIPA....6e6603N"><span id="translatedtitle">Estimation of localized current <span class="hlt">anomalies</span> in polymer electrolyte fuel cells from <span class="hlt">magnetic</span> flux density measurements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nara, Takaaki; Koike, Masanori; Ando, Shigeru; Gotoh, Yuji; Izumi, Masaaki</p> <p>2016-05-01</p> <p>In this paper, we propose novel inversion methods to estimate defects or localized current <span class="hlt">anomalies</span> in membrane electrode assemblies (MEAs) in polymer electrolyte fuel cells (PEFCs). One method is an imaging approach with L1-norm regularization that is suitable for estimation of focal <span class="hlt">anomalies</span> compared to Tikhonov regularization. The second is a complex analysis based method in which multiple pointwise current <span class="hlt">anomalies</span> can be identified directly and algebraically from the measured <span class="hlt">magnetic</span> flux density.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.T43D2705M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.T43D2705M"><span id="translatedtitle">Decay of natural remanent <span class="hlt">magnetization</span> of oceanic basalt on the back-arc <span class="hlt">spreading</span> axis of the southern Mariana</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mochizuki, N.; Nogi, Y.; Asada, M.; Yoshikawa, S.; Okino, K.</p> <p>2012-12-01</p> <p><span class="hlt">Magnetic</span> <span class="hlt">anomaly</span> high on the <span class="hlt">spreading</span> axis is a well-known character of the <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> in the ocean, which is possibly related to <span class="hlt">magnetization</span> intensity reduction of oceanic basalt due to alteration (low-temperature oxidation of titanomagnetite). For a better understanding of natural remanent <span class="hlt">magnetization</span> (NRM) of oceanic basalt, we studied rock-<span class="hlt">magnetic</span> property of basaltic rocks in the back-arc <span class="hlt">spreading</span> axis in the southern Mariana Trough. One to four meter cores were drilled from the seafloor using a Boring Machine System (BMS) in the cruise of TAIGA project (Taiga10M). Block samples were also collected during the dives of SHINKAI6500 in the cruise YK10-11. One-inch specimens drilled from the samples were used for rock-<span class="hlt">magnetic</span> measurements. NRM intensities of these specimens show a clear decrease within 2 km of the ridge axis. Progressive thermal demagnetizations of NRM show that dominant blocking-temperature components are 200-300 and 500-575 °C. Specimens from the ridge axis typically show low blocking-temperature components. On the other hand, specimens collected at 2-5 km distance from the ridge axis show both low and high blocking-temperature components. Alternating field demagnetizations of NRM, anhysteresis remanent <span class="hlt">magnetization</span> (ARM) and isothermal remanent <span class="hlt">magnetization</span> (IRM) indicate that low blocking-temperature components have lower coercivities (<40 mT) while high blocking-temperature components possibly correspond to higher coercivities. These data suggest that high blocking-temperature component is carried by titanomaghemite (or fine magnetite). On the basis of these results, the low blocking-temperature components are considered to be primary thermoremanent <span class="hlt">magnetization</span> (TRM). The high blocking-temperature components are chemical remanent <span class="hlt">magnetization</span> (CRM) acquired during low-temperature alteration which had completed within 2 km of the ridge axis. The NRM intensity shows a decrease within 2 km of the ridge axis, which is similar to a reported result from the East Pacific Rise. Similar spatial scales for the NRM reduction were observed for the ridges of different <span class="hlt">spreading</span> rate suggesting that the low-temperature alteration of oceanic basalt may result from the geological structure around the ridge axis such as active hydrothermal circulation zone rather than the crust's aging which is discussed in previous studies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002AGUSM.T22A..02D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002AGUSM.T22A..02D"><span id="translatedtitle">The Bangui <span class="hlt">Magnetic</span> <span class="hlt">Anomaly</span> Is Not Of Impact Origin</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>DeCarli, P. S.; Jones, A. P.; Price, N. J.; Price, G. D.</p> <p>2002-05-01</p> <p>Ron Girdler et al. suggested a possible impact origin for the Bangui <span class="hlt">magnetic</span> and gravity <span class="hlt">anomaly</span> in Central Africa.1 Paul DeCarli and Ron debated the subject vigorously but politely during each of his visits to California for the Fall AGU Meeting. We honor Ron's memory by continuing the debate. The striking feature of the inferred crater is its size, 800 km diameter. The three largest identified impact craters known on Earth do not exceed 200 km diameter. Grieve has estimated that, based on the record of craters on the Moon, there should be more than a hundred 1000 km-diameter impact structures on the Earth. Allowing for impacts on subsequently subducted oceanic crust, one would expect to find evidence for as many as thirty 1000 km-diameter impact craters on continental crust. If the estimated number of large craters is not grossly in error, one may infer that there could be some natural process that obliterates the evidence for very large craters. We recognize that most of these large craters will be old, ca. 4000 Myr. However, the ca. 200 km diameter Vredefort and Sudbury structures are approximately 2000 Myr old and clearly recognizable as of impact origin. We suggest that very large craters, ca 800 km dia, will probably be inundated by impact-induced volcanism. Impact-induced terrestrial volcanism has been proposed by other workers, but the detailed mechanism has not been treated quantitatively. Consequently, the concept has received little acceptance. We examine the consequences of an impact that would produce an 800 km diameter crater. We note that the final crater diameter is achieved by gravitational modification of a bowl-shaped transient crater. Studies of large lunar and terrestrial craters imply that the transient crater diameter is about half the final diameter. We therefore attempt to infer a range of impact parameters that would produce a 400 km diameter transient crater. Simple semi-empirical scaling relations have been derived from a combination of cm-scale laboratory experiments and generic computational simulations. These scaling relations imply an impacting object having a diameter in the range of 50 to 100 km, assuming a chondritic impactor and an impact velocity of 20 km/s. To assess the possibility that volcanism might be triggered, one must estimate the depth of the transient crater. The aspect ratio, crater depth/crater diameter will depend on the nature of the impactor. A nickel-iron impact will produce a relatively deeper crater than a chondrite impact. Preliminary estimates indicate that the lower bound on the depth is about 80 km. This depth appears sufficient to trigger large-scale decompression melting. Results of computational modeling of the formation of very large impact craters will be presented.. If the Bangui <span class="hlt">anomaly</span> is the fossil of a very large impact, why is there no evidence of large scale volcanism? We suggest that the answer is simple; the Bangui <span class="hlt">anomaly</span> is not of impact origin. 1R.W. Girdler, P.T. Taylor, and J.J. Frawley, Tectonophysics 212 (1992) 45-58</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JGE....13..242P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JGE....13..242P"><span id="translatedtitle"><span class="hlt">Magnetic</span> <span class="hlt">anomaly</span> inversion using <span class="hlt">magnetic</span> dipole reconstruction based on the pipeline section segmentation method</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pan, Qi; Liu, De-Jun; Guo, Zhi-Yong; Fang, Hua-Feng; Feng, Mu-Qun</p> <p>2016-06-01</p> <p>In the model of a horizontal straight pipeline of finite length, the segmentation of the pipeline elements is a significant factor in the accuracy and rapidity of the forward modeling and inversion processes, but the existing pipeline segmentation method is very time-consuming. This paper proposes a section segmentation method to study the characteristics of pipeline <span class="hlt">magnetic</span> anomalies—and the effect of model parameters on these <span class="hlt">magnetic</span> anomalies—as a way to enhance computational performance and accelerate the convergence process of the inversion. Forward models using the piece segmentation method and section segmentation method based on <span class="hlt">magnetic</span> dipole reconstruction (MDR) are established for comparison. The results show that the <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> calculated by these two segmentation methods are almost the same regardless of different measuring heights and variations of the inclination and declination of the pipeline. In the optimized inversion procedure the results of the simulation data calculated by these two methods agree with the synthetic data from the original model, and the inversion accuracies of the burial depths of the two methods are approximately equal. The proposed method is more computationally efficient than the piece segmentation method—in other words, the section segmentation method can meet the requirements for precision in the detection of pipelines by <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> and reduce the computation time of the whole process.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70012295','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70012295"><span id="translatedtitle">Random crustal <span class="hlt">magnetization</span> and its effect on coherence of short-wavelength marine <span class="hlt">magnetic</span> <span class="hlt">anomalies</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Blakely, R.J.</p> <p>1979-01-01</p> <p>Recent studies of DSDP samples from layer 2A of oceanic basement have found complex <span class="hlt">magnetic</span> stratigraphies that seem incompatible with the frequent existence of linear short-wavelength <span class="hlt">anomalies</span> caused by palaeomagnetic field behavior. Statistical models are developed for the lateral variation of the average <span class="hlt">magnetization</span> of layer 2A: a Poisson series for reversals of the earth's field and a stairstep random series for discrete <span class="hlt">magnetic</span> units. It is shown with the power-density spectra of these statistical models that lateral inhomogeneities must average out over distances of less than a few hundred meters. Specifically, individual <span class="hlt">magnetic</span> units of the type seen at DSDP Site 332 cannot extend uniformly for distances greater than a few hundred meters. ?? 1979.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19850023284&hterms=east+african+rift&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Deast%2Bafrican%2Brift','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19850023284&hterms=east+african+rift&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Deast%2Bafrican%2Brift"><span id="translatedtitle">Long-wavelength <span class="hlt">magnetic</span> and gravity <span class="hlt">anomaly</span> correlations on Africa and Europe</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Vonfrese, R. R. B.; Olivier, R.; Hinze, W. J.</p> <p>1985-01-01</p> <p>Preliminary MAGSAT scalar <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> data were compiled for comparison with long-wavelength-pass filtered free-air gravity <span class="hlt">anomalies</span> and regional heat-flow and tectonic data. To facilitate the correlation analysis at satellite elevations over a spherical-Earth, equivalent point source inversion was used to differentially reduce the <span class="hlt">magnetic</span> satellite <span class="hlt">anomalies</span> to the radial pole at 350 km elevation, and to upward continue the first radial derivative of the free-air gravity <span class="hlt">anomalies</span>. Correlation patterns between these regional geopotential <span class="hlt">anomaly</span> fields are quantitatively established by moving window linear regression based on Poisson's theorem. Prominent correlations include direct correspondences for the Baltic shield, where both <span class="hlt">anomalies</span> are negative, and the central Mediterranean and Zaire Basin where both <span class="hlt">anomalies</span> are positive. Inverse relationships are generally common over the Precambrian Shield in northwest Africa, the Basins and Shields in southern Africa, and the Alpine Orogenic Belt. Inverse correlations also presist over the North Sea Rifts, the Benue Rift, and more generally over the East African Rifts. The results of this quantitative correlation analysis support the general inverse relationships of gravity and <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> observed for North American continental terrain which may be broadly related to <span class="hlt">magnetic</span> crustal thickness variations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19840017067&hterms=east+african+rift&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Deast%2Bafrican%2Brift','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19840017067&hterms=east+african+rift&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Deast%2Bafrican%2Brift"><span id="translatedtitle">Long-wavelength <span class="hlt">Magnetic</span> and Gravity <span class="hlt">Anomaly</span> Correlations of Africa and Europe</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Vonfrese, R. R. B.; Hinze, W. J. (Principal Investigator); Olivier, R.</p> <p>1984-01-01</p> <p>Preliminary MAGSAT scalar <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> data were compiled for comparison with long-wavelength-pass filtered free-air gravity <span class="hlt">anomalies</span> and regional heat-flow and tectonic data. To facilitate the correlation analysis at satellite elevations over a spherical-Earth, equivalent point source inversion was used to differentially reduce the <span class="hlt">magnetic</span> satellite <span class="hlt">anomalies</span> to the radial pole at 350 km elevation, and to upward continue the first radial derivative of the free-air gravity <span class="hlt">anomalies</span>. Correlation patterns between these regional geopotential <span class="hlt">anomaly</span> fields are quantitatively established by moving window linear regression based on Poisson's theorem. Prominent correlations include direct correspondences for the Baltic Shield, where both <span class="hlt">anomalies</span> are negative, and the central Mediterranean and Zaire Basin where both <span class="hlt">anomalies</span> are positive. Inverse relationships are generally common over the Precambrian Shield in northwest Africa, the Basins and Shields in southern Africa, and the Alpine Orogenic Belt. Inverse correlations also presist over the North Sea Rifts, the Benue Rift, and more generally over the East African Rifts. The results of this quantitative correlation analysis support the general inverse relationships of gravity and <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> observed for North American continental terrain which may be broadly related to <span class="hlt">magnetic</span> crustal thickness variations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..1215532K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..1215532K"><span id="translatedtitle"><span class="hlt">Magnetic</span> <span class="hlt">Anomalies</span> of the Fennoscandian Shield on a 2km resolution grid</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Korhonen, Juha V.; Aaro, Sven; Reidar Skilbrei, Jan; All, Tarmo</p> <p>2010-05-01</p> <p>Joint <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> grid of the Fennoscandian Shield was released 2002, smoothed and used as data for the WDMAM2007. In comparison with MF5 this grid showed superior characteristics to other sets. The data will be released as a 2 km resolution grid for the WDMAM2011 with eventual updates of <span class="hlt">anomaly</span> levels.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1984mags.rept...46V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1984mags.rept...46V"><span id="translatedtitle">Long-wavelength <span class="hlt">magnetic</span> and gravity <span class="hlt">anomaly</span> correlations of Africa and Europe</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vonfrese, R. R. B.; Hinze, W. J.; Olivier, R.</p> <p>1984-01-01</p> <p>Preliminary MAGSAT scalar <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> data were compiled for comparison with long-wavelength-pass filtered free-air gravity <span class="hlt">anomalies</span> and regional heat-flow and tectonic data. To facilitate the correlation analysis at satellite elevations over a spherical-Earth, equivalent point source inversion was used to differentially reduce the <span class="hlt">magnetic</span> satellite <span class="hlt">anomalies</span> to the radial pole at 350 km elevation, and to upward continue the first radial derivative of the free-air gravity <span class="hlt">anomalies</span>. Correlation patterns between these regional geopotential <span class="hlt">anomaly</span> fields are quantitatively established by moving window linear regression based on Poisson's theorem. Prominent correlations include direct correspondences for the Baltic Shield, where both <span class="hlt">anomalies</span> are negative, and the central Mediterranean and Zaire Basin where both <span class="hlt">anomalies</span> are positive. Inverse relationships are generally common over the Precambrian Shield in northwest Africa, the Basins and Shields in southern Africa, and the Alpine Orogenic Belt. Inverse correlations also presist over the North Sea Rifts, the Benue Rift, and more generally over the East African Rifts. The results of this quantitative correlation analysis support the general inverse relationships of gravity and <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> observed for North American continental terrain which may be broadly related to <span class="hlt">magnetic</span> crustal thickness variations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6386208','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/biblio/6386208"><span id="translatedtitle">Apparatus and method for detecting a <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> contiguous to remote location by SQUID gradiometer and magnetometer systems</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Overton, W.C. Jr.; Steyert, W.A. Jr.</p> <p>1981-05-22</p> <p>A superconducting quantum interference device (SQUID) <span class="hlt">magnetic</span> detection apparatus detects <span class="hlt">magnetic</span> fields, signals, and <span class="hlt">anomalies</span> at remote locations. Two remotely rotatable SQUID gradiometers may be housed in a cryogenic environment to search for and locate unambiguously <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>. The SQUID <span class="hlt">magnetic</span> detection apparatus can be used to determine the azimuth of a hydrofracture by first flooding the hydrofracture with a ferrofluid to create an artificial <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> therein.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JAG...113...14G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JAG...113...14G"><span id="translatedtitle">Forward modeling of total <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> over a pseudo-2D underground ferromagnetic pipeline</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Guo, Zhi-Yong; Liu, De-Jun; Pan, Qi; Zhang, Ying-Ying</p> <p>2015-02-01</p> <p><span class="hlt">Magnetic</span> <span class="hlt">anomalies</span> are formed by the superposition of earth's <span class="hlt">magnetic</span> field and the induced field of an underground ferromagnetic pipeline. To analyze the influence of all factors on the detected <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>, a forward model is established in this paper. A numerical integration method, <span class="hlt">magnetic</span> dipole reconstruction (MDR), for <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> forward modeling is proposed, and a series of calculations is performed between model parameters of the pipeline, the geomagnetic field, the measuring trace, and total <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> (TMA). The influence of model parameters on the shape, amplitude, and <span class="hlt">magnetic</span> width is then analyzed. Results show that the shape of TMA curve is primarily influenced by the <span class="hlt">magnetic</span> inclination and relative azimuth of the pipeline. The amplitude is linearly related to geomagnetic intensity and pipeline parameters including diameter, thickness, and susceptibility, and decreases in inverse proportion to increase in distance between the pipeline's axis and measurement plane; it decreases in a cosine manner with decrease in inclination and relative azimuth. The <span class="hlt">magnetic</span> width is less affected by the geomagnetic intensity and pipeline parameters, but does increase with increase in distance between the pipeline's axis and measurement plane, and decreases with decreasing inclination and relative azimuth. The MDR method effectively simulates the distributions of TMA caused by various models of pseudo-2D underground ferrous pipeline. <span class="hlt">Magnetic</span> <span class="hlt">anomaly</span> detection (MAD) does not effectively estimate existence or orientation of pipeline that are deeply-buried, slender or with axes parallel to the earth's <span class="hlt">magnetic</span> field in the low <span class="hlt">magnetic</span> latitude area. Rough measurement of <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> is necessary before the orientation of the underground pipeline is identified, followed by exact measurements along the perpendicular direction of the axis of pipeline to accurately locate underground pipeline.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUFM.P51C0670H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUFM.P51C0670H"><span id="translatedtitle">Modelling and interpreting <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> features over lunar mare using a GIS method</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hemant, K.; Purucker, M.; Sabaka, T.</p> <p>2007-12-01</p> <p>The global <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> maps derived from the Lunar Prospector vector magnetometer data has revealed weak <span class="hlt">anomalies</span> over the regions flooded by lunar mare basalts and strong <span class="hlt">anomalies</span> over the regions diametrically opposite to some of the largest basin-forming impact craters. Conversely, the spectrometer data over the Lunar mare show a high concentration of FeO by weight, suggesting that iron could mostly be present in the form of ilmenites and other high Titanium oxide. Among the mare basins, Crisium and Marginis show <span class="hlt">anomaly</span> strength > 4 nT at 30 km altitude while Serenitatis, Fecundiatis, Nectaris, Australe and Moscoviense show strength < 4 nT. Large mare basins Imbrium and Orientale show the weakest features < 1.5 nT. The <span class="hlt">anomalies</span> are modelled in terms of vertically integrated <span class="hlt">magnetization</span> model of the lunar crust. The lunar crustal thickness model, paleomagnetic measurements of the samples collected from Apollo Lunar mission and the known geological regions covering the lunar mare are combined together following a Geographic Information System based technique to compute a lunar crustal <span class="hlt">magnetization</span> model (LCMM). Vector <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> maps are predicted at an altitude of 30 km using LCMM and are compared with the corresponding observed <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> map. The sources causing the <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>, in particular the thickness of the underlying basalts are modified to match the observations. Some of the regions, for instance north of Mare Marginis, not occupied by the present known surface expression of the mare regions also show strong <span class="hlt">anomaly</span> features whose causative sources need to be understood and modelled.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JAG...117...23W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JAG...117...23W"><span id="translatedtitle">Lithologic mapping test for gravity and <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>. A case study of gravity-<span class="hlt">magnetic</span> <span class="hlt">anomaly</span> profile in the eastern segment of the China-Mongolia border</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Jian; Meng, Xiaohong; Chen, Zhaoxi; Liu, Guofeng; Zheng, Yuanman; Wang, Jun; Zhang, Sheng; Zhang, Xingdong; Zheng, Wanqiu</p> <p>2015-06-01</p> <p>An inversion calculation is usually needed to map lithologies with gravity-<span class="hlt">magnetic</span> <span class="hlt">anomalies</span>. A lithological-physical property correspondence can be established by combining data of regional rock density and <span class="hlt">magnetic</span> susceptibility to build topological equations. In this study, topological calculations were performed using inversion data and combined with physical property data to interpret and map lithologies. Gravity-<span class="hlt">magnetic</span> profiles from the eastern segment of the China-Mongolia border were used (Jining-Bainaimiao-Ha'ernaode geological-composite geophysical profile) in this paper. Based on gravity-<span class="hlt">magnetic</span> <span class="hlt">anomaly</span> inversion, the rock density and <span class="hlt">magnetic</span> susceptibility data of Bainaimiao and Jining were adopted for lithological inversion. Distribution characteristics of four major types of magmatic rocks within 50 km of the lower half space were obtained, and results of lithologic mapping and tectonic framework were analyzed. The position of convergence between the North China Plate and Siberian Plate was confirmed. Two tectonic stages were identified, namely, interplate squeezing and intraplate deformation. Regional gravity-<span class="hlt">magnetic</span> field properties were analyzed to discuss the orientation and date of andesites and diorites in the northern part of the survey line. We believe that they have a northeast-southwest orientation similar to gravity-<span class="hlt">magnetic</span> <span class="hlt">anomalies</span> of Erenhot-Xilinhot. They resemble the igneous rock near Erenhot because they both indicate magmatic intrusion during the early Carboniferous.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.usgs.gov/of/1977/0463/report.pdf','USGSPUBS'); return false;" href="http://pubs.usgs.gov/of/1977/0463/report.pdf"><span id="translatedtitle">Calculation of gravity and <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> along profiles with end corrections and inverse solutions for density and <span class="hlt">magnetization</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Cady, John W.</p> <p>1977-01-01</p> <p>A computer program is presented which performs, for one or more bodies, along a profile perpendicular to strike, both forward calculations for the <span class="hlt">magnetic</span> and gravity <span class="hlt">anomaly</span> fields and independent gravity and <span class="hlt">magnetic</span> inverse calculations for density and susceptibility or remanent <span class="hlt">magnetization</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003EAEJA.....2587T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003EAEJA.....2587T"><span id="translatedtitle">High-altitude structure of the <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> using the gradient measurements in stratosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tsvetkov, Yu.; Rotanova, N.; Belikova, M.</p> <p>2003-04-01</p> <p>HIGH-ALTITUDE STRUCTURE OF THE <span class="hlt">MAGNETIC</span> <span class="hlt">ANOMALIES</span> USING THE GRADIENT MEASUREMENTS IN STRATOSPHERE Yu. Tsvetkov, N. ROTANOVA, M. Belikova Institute of Terrestrial <span class="hlt">Magnetism</span>, Ionosphere and Radio Wave Propagation RAS, Troitsk, Moscow Region, 142190, Russia rotanova@izmiran.rssi.ru/FAX: +7-095-3340124 Method of the recalculation of the <span class="hlt">anomaly</span> <span class="hlt">magnetic</span> field over the range of the altitudes of 20-40 km is suggested. Technique is based on the experimental data of the <span class="hlt">anomaly</span> <span class="hlt">magnetic</span> field, its vertical gradient and the gradient increment along vertical line, obtained from the aerostat gradient <span class="hlt">magnetic</span> surveys in stratosphere. The high-altitude structure of the <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>, obtained for the Baikal region has been constructed. These results were used to obtain the estimations of the deep <span class="hlt">magnetic</span> sources. The numerous values of the low boundary of the sources are 30-35 km. These estimations of the depth coincide with the ones, obtained from the results of the spectral analysis of the same <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active"><span>7</span></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_7 --> <div id="page_8" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="141"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JGRE..120.1160T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JGRE..120.1160T"><span id="translatedtitle">Surface vector mapping of <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> over the Moon using Kaguya and Lunar Prospector observations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tsunakawa, Hideo; Takahashi, Futoshi; Shimizu, Hisayoshi; Shibuya, Hidetoshi; Matsushima, Masaki</p> <p>2015-06-01</p> <p>We have provided preliminary global maps of three components of the lunar <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> on the surface applying the surface vector mapping (SVM) method. The data used in the present study consist of about 5 million observations of the lunar <span class="hlt">magnetic</span> field at 10-45 km altitudes by Kaguya and Lunar Prospector. The lunar <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> were mapped at 0.2° equi-distance points on the surface by the SVM method, showing the highest intensity of 718 nT in the Crisium antipodal region. Overall features on the SVM maps indicate that elongating <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> are likely to be dominant on the Moon except for the young large basins with the impact demagnetization. Remarkable demagnetization features suggested by previous studies are also recognized at Hertzsprung and Kolorev craters on the farside. These features indicate that demagnetized areas extend to about 1-2 radii of the basins/craters. There are well-isolated central <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> at four craters: Leibnitz, Aitken, Jules Verne, and Grimaldi craters. Their <span class="hlt">magnetic</span> poles through the dipole source approximation suggest occurrence of the polar wander prior to 3.3-3.5 Ga. When compared with high-albedo markings at several <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> such as the Reiner Gamma <span class="hlt">anomalies</span>, three-dimensional structures of the <span class="hlt">magnetic</span> field on/near the surface are well correlated with high-albedo areas. These results indicate that the global SVM maps are useful for the study of the lunar <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> in comparison with various geological and geophysical data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19860052866&hterms=Toft&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DToft','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19860052866&hterms=Toft&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DToft"><span id="translatedtitle">A remanent and induced <span class="hlt">magnetization</span> model of Magsat vector <span class="hlt">anomalies</span> over the west African craton</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Toft, P. B.; Haggerty, S. E.</p> <p>1986-01-01</p> <p>Scalar and vector Magsat <span class="hlt">anomalies</span> over the west African craton are analyzed by forward and inverse models. A forward model of the Man shield is based on Liberia. Induced <span class="hlt">magnetization</span> contrasts due to sporadic iron-formations and to regional metamorphic rocks, and a contrast in remanent <span class="hlt">magnetization</span> within the lower crust are included. This combination reproduces the location, magnitude and adopted local zero level of <span class="hlt">anomalies</span> in the initial Magsat maps. An inverse model of the Reguibat shield estimates the <span class="hlt">magnetization</span> contrast of its lithosphere, and when <span class="hlt">magnetism</span> is restricted to shallower than 75 km both shields can be represented by a susceptibility contrast of +0.02. A residual <span class="hlt">anomaly</span> between the shields involves a relative deficiency of induced <span class="hlt">magnetization</span> along with other causes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70011277','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70011277"><span id="translatedtitle">Statistical averaging of marine <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> and the aging of oceanic crust.</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Blakely, R.J.</p> <p>1983-01-01</p> <p>Visual comparison of Mesozoic and Cenozoic <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> in the North Pacific suggests that older <span class="hlt">anomalies</span> contain less short-wavelength information than younger <span class="hlt">anomalies</span> in this area. To test this observation, <span class="hlt">magnetic</span> profiles from the North Pacific are examined from crust of three ages: 0-2.1, 29.3-33.1, and 64.9-70.3Ma. For each time period, at least nine profiles were analyzed by 1) calculating the power density spectrum of each profile, 2) averaging the spectra together, and 3) computing a 'recording filter' for each time period by assuming a hypothetical seafloor model. The model assumes that the top of the source is acoustic basement, the source thickness is 0.5km, and the time scale of geomagnetic reversals is according to Ness et al. (1980). The calculated power density spectra of the three recording filters are complex in shape but show an increase of attenuation of short-wavelength information as the crust ages. These results are interpreted using a multilayer model for marine <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> in which the upper layer, corresponding to pillow basalt of seismic layer 2A, acts as a source of noise to the <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>. As the ocean crust ages, this noisy contribution by the pillow basalts becomes less significant to the <span class="hlt">anomalies</span>. Consequently, <span class="hlt">magnetic</span> sources below layer 2A must be faithful recorders of geomagnetic reversals.-AuthorPacific power density spectrum</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013MeScT..24g5005Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013MeScT..24g5005Y"><span id="translatedtitle">Characterization of CHAMP <span class="hlt">magnetic</span> data <span class="hlt">anomalies</span>: <span class="hlt">magnetic</span> contamination and measurement timing</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yin, Fan; Lhr, Hermann; Rauberg, Jan; Michaelis, Ingo; Cai, Hongtao</p> <p>2013-07-01</p> <p>The CHAMP (CHAllenging Minisatellite Payload) mission ended after more than ten years in space on 19 September 2010. For achieving a high measurement accuracy of the magnetometers on CHAMP, detailed analyses of spacecraft <span class="hlt">magnetic</span> characteristics in orbit are required. A decade of continuous magnetometer and housekeeping data are a good basis for evaluating some of the effects of variable spacecraft <span class="hlt">magnetic</span> fields on the ambient field determination. It was found that some perturbations of FGM (FluxGate vector Magnetometer) or OVM (OVerhauser scalar Magnetometer) measurements are caused by stray fields induced by the power system, the ASC (advanced stellar compass) instrument or magneto-torquer currents. The <span class="hlt">magnetic</span> effect of solar currents on FGM measurements varies with the local time of the orbit and amounts to 0.2 nT. In cases when one head of the ASC instrument was blinded by the sun, sometimes transient drops in instrument current strength occur, which were accompanied by <span class="hlt">magnetic</span> disturbance signals (?0.3 nT) in FGM measurements. The <span class="hlt">magnetic</span> residual contamination of OVM data by the torquer currents was of order 0.1 nT but still detectable. An improved torquer correction matrix is derived which eliminates this effect. In-flight scalar calibration parameters revealed some of the effects of timing <span class="hlt">anomalies</span>. Time lags between FGM and OVM readings are misinterpreted by the scalar calibration as variations of the angles between some of the sensor axes. The resulting amplitudes of the <span class="hlt">anomalies</span> presented here lie in the range of some 0.1 nT, but they are systematic in nature.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..1412169V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..1412169V"><span id="translatedtitle">Direct Observations of <span class="hlt">Magnetic</span> <span class="hlt">Anomalies</span> on the Lunar Surface under Varying Solar Wind Conditions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vorburger, A.; Wurz, P.; Barabash, S.; Wieser, M.; Futaana, Y.; Holmström, M.; Bhardwaj, A.; Dhanya, M. B.; Sridharan, R.; Asamura, K.</p> <p>2012-04-01</p> <p>In contrast to Earth, the Moon does not have a global dipolar <span class="hlt">magnetic</span> field. Since the first lunar landing with Apollo 11, we know, though, that localised <span class="hlt">magnetic</span> fields exist on the lunar surface. Measurements conducted by the Lunar Prospector magnetometer and electron reflectometer suggested that these localised <span class="hlt">magnetic</span> fields are able to deflect the impinging solar wind in favourable cases (Lin et al., Science 1998). Magnetohydrodynamic simulations support the implication that mini-magnetospheres are formed above the locations of strong localised <span class="hlt">magnetic</span> fields and can hold off the impinging solar wind (Harnett and Winglee, JGR 2002). Analysis of <span class="hlt">magnetic</span> field data from Lunar Prospector of the Reiner Gamma <span class="hlt">anomaly</span> region showed that the distortion of the <span class="hlt">magnetic</span> field of this <span class="hlt">anomaly</span> strongly depends on the impinging solar wind parameters, which was interpreted that the size and shape of the mini-magnetosphere changed with the solar wind parametes (Kurata et al., GRL 2005). Wieser et al., GRL 2010 showed that SARA, the Sub-KeV Atom Analyzer on board Chandrayaan-1, is able to detect an ENA image of the mini-magnetosphere in the measured energetic neutral atom flux. Here we analysed all orbits where CENA, the Chandrayaan-1 Energetic Neutral Analyzer, recorded data when a <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> was in CENA's field-of-view. Our goal was to determine if 1) a signature of the <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> is always visible in the ENA signal and if 2) there is a correlation between the solar wind dynamic pressure, the solar wind <span class="hlt">magnetic</span> field, the local <span class="hlt">magnetic</span> field strength and the reduction in the reflected ENA flux. Our results show that for the simplest case, i.e., the Gerasimovich <span class="hlt">anomaly</span>, there is indeed a clear correlation between the shielding efficiency, the <span class="hlt">magnetic</span> field strength and the solar wind dynamic pressure. For the other observed <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>, for which the <span class="hlt">magnetic</span> fields are not only weaker but also spatially more variable than that of the Gerasimovich <span class="hlt">anomaly</span>, only in about half of the cases such a correlation was found. We therefore conclude that the <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> interaction is in general quite complex and that data with higher spatial resolution and more detailed modelling is required to understand this process better.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMGP13B1123G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMGP13B1123G"><span id="translatedtitle">Callovian (upper Middle Jurassic) magnetostratigraphy and its correlation to Pacific marine <span class="hlt">magnetic</span> <span class="hlt">anomalies</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gipe, R.; Ogg, J. G.</p> <p>2012-12-01</p> <p>A nearly continuous composite geomagnetic polarity reference sequence spanning the latest Bathonian (Discus Zone) through entire Callovian and into the earliest Oxfordian (Mariae and Cordatum zones) was complied from 14 ammonite- and/or brachiopod-zoned sections from England, France and Southern Germany. Additional inter-section correlations and adjustment for local hiatuses were provided by basinal sequence stratigraphy. The Callovian is dominated by normal polarity, with three clusters of relatively brief reversed-polarity zones. A subset of the 391 samples were filtered according to <span class="hlt">magnetic</span> behavior, and the highest quality suite (representing outcrops) produced an average paleopole of 66°N, 171°E (δp=11°, δm=16°) for England and of approximately 75°N, 149°E (δp=11°, δm=15°) for France. The main aspects of the magnetostratigraphy pattern mirror the general trends of Callovian-age marine <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> in the Western Pacific as determined by deep-tow <span class="hlt">magnetic</span> surveys in the Pacific basin. This geomagnetic polarity reference sequence, scaled with cycle stratigraphy where available, confirms and calibrates the main features of the Pacific marine <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> model from <span class="hlt">anomaly</span> M37 and older. The top of the Callovian correlates with the marine <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> M37n (tentatively to the lower part of subchron M37n.1n) and the base of the Callovian is within marine <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> M39n.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19840017064&hterms=Curie&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DCurie','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19840017064&hterms=Curie&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DCurie"><span id="translatedtitle">Reduced to Pole Long-wavelength <span class="hlt">Magnetic</span> <span class="hlt">Anomalies</span> of Africa and Europe</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hinze, W. J.; Vonfrese, R. R. B. (Principal Investigator); Olivier, R.</p> <p>1984-01-01</p> <p>To facilitate analysis of the tectonic framework for Africa, Europe and adjacent marine areas, MAGSAT scalar <span class="hlt">anomaly</span> data are differentially reduced to the pole and compared to regional geologic information and geophysical data including surface free-air gravity <span class="hlt">anomaly</span> data upward continued to satellite elevation (350 km) on a spherical Earth. Comparative analysis shows <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> correspond with both ancient as well as more recent Cenozoic structural features. <span class="hlt">Anomalies</span> associated with ancient structures are primarily caused by intra-crustal lithologic variations such as the crustal disturbance associated with the Bangui <span class="hlt">anomaly</span> in west-central Africa. <span class="hlt">Anomalies</span> correlative with Cenozoic tectonic elements appear to be related to Curie isotherm perturbations. A possible example of the latter is the well-defined trend of <span class="hlt">magnetic</span> minima that characterize the Alpine orogenic belt from the Atlas mountains to Eurasia. In contrast, a well-defined <span class="hlt">magnetic</span> satellite minimum extends across the stable craton from Finland to the Ural mountains. Prominent <span class="hlt">magnetic</span> maxima characterize the Arabian plate, Iceland, the Kursk region of the central Russian uplift, and generally the Precambrian shields of Africa.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19850023282&hterms=Curie&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DCurie','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19850023282&hterms=Curie&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DCurie"><span id="translatedtitle">Reduced to pole long-wavelength <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> of Africa and Europe</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Olivier, R.; Hinze, W. J.; Vonfrese, R. R. B.</p> <p>1985-01-01</p> <p>To facilitate analysis of the tectonic framework for Africa, Europe and adjacent marine areas, MAGSAT scalar <span class="hlt">anomaly</span> data are differentially reduced to the pole and compared to regional geologic information and geophysical data including surface free-air gravity <span class="hlt">anomaly</span> data upward continued to satellite elevation (350 km) on a spherical Earth. Comparative analysis shows <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> correspond with both ancient as well as more recent Cenozoic structural features. <span class="hlt">Anomalies</span> associated with ancient structures are primarily caused by intra-crustal lithologic variations such as the crustal disturbance associated with the Bangui <span class="hlt">anomaly</span> in west-central Africa. <span class="hlt">Anomalies</span> correlative with Cenozoic tectonic elements appear to be related to Curie isotherm perturbations. A possible example of the latter is the well-defined trend of <span class="hlt">magnetic</span> minima that characterize the Alphine orogenic belt from the Atlas mountains to Eurasia. In contrast, a well-defined <span class="hlt">magnetic</span> satellite minimum extends across the stable craton from Finland to the Ural mountains. Prominent <span class="hlt">magnetic</span> maxima characterize the Arabian plate, Iceland, the Kursk region of the central Russian uplift, and generally the Precambrian shields of Africa.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016Ge%26Ae..56..239A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016Ge%26Ae..56..239A"><span id="translatedtitle">Changes of lithospheric <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> with altitude (According to the CHAMP satellite)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Abramova, D. Yu.; Filippov, S. V.; Abramova, L. M.; Varentsov, I. M.; Lozovskii, I. N.</p> <p>2016-03-01</p> <p>Maps of the magnitude of the full vector and the vertical component of an anomalous lithospheric <span class="hlt">magnetic</span> field over the Voronezh anticline (VA) for the three high-altitude observation levels were compiled based on geomagnetic measurements from the CHAMP satellite. The isometric positive <span class="hlt">anomaly</span> centered at about 50° N and 37° E stands out. Its amplitude decreases with increasing observation altitude without changing the form. Comparison of the parameters of the detected <span class="hlt">anomaly</span> with data obtained for this site by other methods confirms that it really exists and that its spatial position is accurately determined, which indicates the reliability of the values of the selected field of lithospheric <span class="hlt">anomalies</span>. The change in the parameters of the <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> with respect to the observation level over the Earth's surface is consistent with the concepts of geological structural features of the lithosphere in the region. The <span class="hlt">anomaly</span> offset to the south on the satellite altitudes apparently indicates an uplift of crystalline basement rocks and a more southern position of VA deep roots relative to that accepted in the global <span class="hlt">magnetization</span> model. The use of satellite data obtained at different altitudes opens up additional possibilities for the application of gradient methods in the interpretation of the <span class="hlt">magnetic</span> fields of lithospheric <span class="hlt">anomalies</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20030025340&hterms=RAE&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DRAE','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20030025340&hterms=RAE&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DRAE"><span id="translatedtitle">Satellite-Altitude Geopotential Study of the Kursk <span class="hlt">Magnetic</span> <span class="hlt">Anomaly</span> (KMA)</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Taylor, Patrick T.; Kim, Hyung Rae; vonFrese, Ralph R. B.; Potts, Laramie V.; Frawley, James J.</p> <p>2003-01-01</p> <p>With the successful launch of the Orsted, SAC-C and CHAMP satellites we are able to make both <span class="hlt">magnetic</span> and gravity <span class="hlt">anomaly</span> maps of the Earth's crust; <span class="hlt">magnetic</span> from all three missions and gravity with CHAMP. We have used these data to study the KMA area of Russia. This is an important region for several reasons: (1) we have already made satellite <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> maps of this region and they can be integrated with the gravity data from CHAMP for a comprehensive interpretation; (2) KMA contains the largest know reserves of iron-ore in the world; and (3) there are significant ground truth data available for this region from aeromagnetic, balloon surveys and geophysical mapping, including extensive rock <span class="hlt">magnetic/paleo-magnetic</span> and geologic studies. Utilizing the gravity observations, collocated with the <span class="hlt">magnetic</span> data enabled us to make a joint interpretation. While there is a high amplitude <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> recorded over the KMA the gravity <span class="hlt">anomaly</span> at satellite altitude revealed by CHAMP is only around 3-6 mGal but is not centered on the <span class="hlt">magnetic</span> high. This would indicate that despite the fact that in the region of the KMA the rocks have a higher percentage of iron than in the surrounding formations the entire area is Archean-Proterozoic in age and therefore very dense.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19810047271&hterms=flat+earth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dflat%2Bearth','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19810047271&hterms=flat+earth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dflat%2Bearth"><span id="translatedtitle">Spherical earth gravity and <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> analysis by equivalent point source inversion</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Von Frese, R. R. B.; Hinze, W. J.; Braile, L. W.</p> <p>1981-01-01</p> <p>To facilitate geologic interpretation of satellite elevation potential field data, analysis techniques are developed and verified in the spherical domain that are commensurate with conventional flat earth methods of potential field interpretation. A powerful approach to the spherical earth problem relates potential field <span class="hlt">anomalies</span> to a distribution of equivalent point sources by least squares matrix inversion. Linear transformations of the equivalent source field lead to corresponding geoidal <span class="hlt">anomalies</span>, pseudo-<span class="hlt">anomalies</span>, vector <span class="hlt">anomaly</span> components, spatial derivatives, continuations, and differential <span class="hlt">magnetic</span> pole reductions. A number of examples using 1 deg-averaged surface free-air gravity <span class="hlt">anomalies</span> of POGO satellite magnetometer data for the United States, Mexico, and Central America illustrate the capabilities of the method.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1711384A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1711384A"><span id="translatedtitle">Interaction of Solar Wind and <span class="hlt">Magnetic</span> <span class="hlt">Anomalies</span> - Modelling from Moon to Mars</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Alho, Markku; Kallio, Esa; Wedlund, Cyril Simon; Wurz, Peter</p> <p>2015-04-01</p> <p>The crustal <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> on both the Moon and Mars strongly affect the local plasma environment. On the Moon, the impinging solar wind is decelerated or deflected when interacting with the <span class="hlt">magnetic</span> field <span class="hlt">anomaly</span>, visible in the lunar surface as energetic neutral atom (ENA) emissions or as reflected protons, and may play a part in the space weathering of the lunar soil. At Mars, the crustal <span class="hlt">magnetic</span> fields have been shown to be associated with, e.g., enhanced electron scale heights and modified convection of ionospheric plasma, resulting in the plasma environment being dominated by crustal <span class="hlt">magnetic</span> fields up to altitudes of 400km. Our previous modelling work suggested that Hall currents are a dominant feature in a Moon-like <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> interaction at scales at or below the proton inertial length. In this work we study the solar wind interaction with <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> and compare the plasma environments of a Moon-like <span class="hlt">anomaly</span> with a Mars-like <span class="hlt">anomaly</span> by introducing an ionosphere and an exosphere to probe the transition from an atmosphere-less <span class="hlt">anomaly</span> interaction to an ionospheric one. We utilize a 3D hybrid plasma model, in which ions are modelled as particles while electrons form a charge-neutralizing massless fluid. The hybrid model gives a full description of ion kinetics and associated plasma phenomena at the simulation region ranging from instabilities to possible reconnection. The model can thus be used to interpret both in-situ particle and field observations and remotely-sensed ENA emissions. A self-consistent ionosphere package for the model is additionally in development.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/415620','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/415620"><span id="translatedtitle">Weak extremely-low-frequency <span class="hlt">magnetic</span> field-induced regeneration <span class="hlt">anomalies</span> in the planarian, Dugesia tigrina</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Jenrow, K.A.; Smith, C.H.; Liboff, A.R.</p> <p>1996-12-31</p> <p>The authors recently reported that cephalic regeneration in the planarian Dugesia tigrina was significantly delayed in populations exposed continuously to combined parallel DC and AC <span class="hlt">magnetic</span> fields. This effect was consistent with hypotheses suggesting an underlying resonance phenomenon. The authors report here, in a parallel series of investigations on the same model system, that the incidence of regeneration <span class="hlt">anomalies</span> presenting as tumor-like protuberances also increases significantly (P < .001) in association with exposure to weak 60 Hz <span class="hlt">magnetic</span> fields, with peak intensities ranging between 1.0 and 80.0 {micro}T. These <span class="hlt">anomalies</span> often culminate in the complete disaggregation of the organism. Similar to regeneration rate effects, the incidence of regeneration <span class="hlt">anomalies</span> is specifically dependent upon the planaria possessing a fixed orientation with respect to the applied <span class="hlt">magnetic</span> field vectors. However, unlike the regeneration rate effects, the AC <span class="hlt">magnetic</span> field alone, in the absence of any measurable DC field, is capable of producing these <span class="hlt">anomalies</span>. Moreover, the incidence of regeneration <span class="hlt">anomalies</span> follows a clear dose-response relationship as a function of AC <span class="hlt">magnetic</span> field intensity, with the threshold for induced electric field intensity estimated at 5 {micro} V/m. The addition of either 51.1 or 78.4 {micro}T DC <span class="hlt">magnetic</span> fields, applied in parallel combination with the AC field, enhances the appearance of <span class="hlt">anomalies</span> relative to the 60 Hz AC field alone, but only at certain AC field intensities. Thus, whereas the previous study of regeneration rate effects appeared to involve exclusively resonance interactions, the regeneration <span class="hlt">anomalies</span> reported here appear to result primarily from Faraday induction coupling.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1994JGR....9924075A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1994JGR....9924075A"><span id="translatedtitle">Scalar <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> maps of Earth derived from POGO and Magsat data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Arkani-Hamed, Jafar; Langel, Robert A.; Purucker, Mike</p> <p>1994-12-01</p> <p>A new Polar Orbit Geophysical Observatory (POGO) scalar <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> map at 400 km altitude is presented which consists of spherical harmonics of degree 15-60. On the basis of the common features of this map with two new Magsat <span class="hlt">anomaly</span> maps, dawn and dusk, two scalar <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> maps of the Earth are presented using two selection criteria with different levels of stringency. These selection criteria suppress the noncrustal components of the original maps by different amounts. The more stringent selection criteria seek to eliminate as much contamination as possible, at the expense of suppressing some <span class="hlt">anomaly</span> signal. This map is represented by spherical harmonics of degree 15-60. The less stringent selection criteria seek to retain as much crustal signal as possible, at the expense of also retaining some contaminating fields. This map is represented by spherical harmonics of degree 15-65. The resulting two maps are highly correlated with degree correlation coefficients greater than 0.8.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19850044263&hterms=Seamounts&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DSeamounts','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19850044263&hterms=Seamounts&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DSeamounts"><span id="translatedtitle">Intermediate-wavelength <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> field of the North Pacific and posible source distributions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Labrecque, J. L.; Cande, S. C.; Jarrard, R. D.</p> <p>1985-01-01</p> <p>A technique that eliminates external field sources and the effects of strike aliasing was used to extract from marine survey data the intermediate wavelength <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> field for (B) in the North Pacific. A strong correlation exists between this field and the Magsat field although a directional sensitivity in the Magsat field can be detected. The intermediate wavelength field is correlated to tectonic features. Island arcs appear as positive <span class="hlt">anomalies</span> of induced origin likely due to variations in crustal thickness. Seamount chains and oceanic plateaus also are manifested by strong <span class="hlt">anomalies</span>. The primary contribution to many of these <span class="hlt">anomalies</span> appears to be due to a remanent <span class="hlt">magnetization</span>. The source parameters for the remainder of these features are presently unidentified ambiguous. Results indicate that the sea surface field is a valuable source of information for secular variation analysis and the resolution of intermediate wavelength source parameters.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19830006325','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19830006325"><span id="translatedtitle">The intermediate wavelength <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> field of the north Pacific and possible source distributions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Labrecque, J. L.; Cande, S. C.; Jarrard, R. D. (Principal Investigator)</p> <p>1983-01-01</p> <p>A technique that eliminates external field sources and the effects of strike aliasing was used to extract from marine survey data the intermediate wavelength <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> field for (B) in the North Pacific. A strong correlation exists between this field and the MAGSAT field although a directional sensitivity in the MAGSAT field can be detected. The intermediate wavelength field is correlated to tectonic features. Island arcs appear as positive <span class="hlt">anomalies</span> of induced origin likely due to variations in crustal thickness. Seamount chains and oceanic plateaus also are manifested by strong <span class="hlt">anomalies</span>. The primary contribution to many of these <span class="hlt">anomalies</span> appears to be due to a remanent <span class="hlt">magnetization</span>. The source parameters for the remainder of these features are presently unidentified ambiguous. Results indicate that the sea surface field is a valuable source of information for secular variation analysis and the resolution of intermediate wavelength source parameters.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19950048348&hterms=B12&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DB12','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19950048348&hterms=B12&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DB12"><span id="translatedtitle">Scalar <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> maps of Earth derived from POGO and Magsat data</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Arkani-Hamed, Jafar; Langel, Robert A.; Purucker, Mike</p> <p>1994-01-01</p> <p>A new Polar Orbit Geophysical Observatory (POGO) scalar <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> map at 400 km altitude is presented which consists of spherical harmonics of degree 15-60. On the basis of the common features of this map with two new Magsat <span class="hlt">anomaly</span> maps, dawn and dusk, two scalar <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> maps of the Earth are presented using two selection criteria with different levels of stringency. These selection criteria suppress the noncrustal components of the original maps by different amounts. The more stringent selection criteria seek to eliminate as much contamination as possible, at the expense of suppressing some <span class="hlt">anomaly</span> signal. This map is represented by spherical harmonics of degree 15-60. The less stringent selection criteria seek to retain as much crustal signal as possible, at the expense of also retaining some contaminating fields. This map is represented by spherical harmonics of degree 15-65. The resulting two maps are highly correlated with degree correlation coefficients greater than 0.8.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19840007562','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19840007562"><span id="translatedtitle"><span class="hlt">Magnetic</span> <span class="hlt">anomalies</span> in east Pacific using MAGSAT data</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Harrison, C. G. A. (Principal Investigator)</p> <p>1983-01-01</p> <p>Methods for solving problems encountered in separating the core field from the crustal field are summarized as well as those methods developed for inverting total <span class="hlt">magnetic</span> field data to obtain source functions for oceanic areas. Accounting for <span class="hlt">magnetization</span> contrasts and the <span class="hlt">magnetization</span> values measured in rocks of marine origin are also discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19840014940','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19840014940"><span id="translatedtitle">Application of Magsat lithospheric modeling in South America. Part 1: Processing and interpretation of <span class="hlt">magnetic</span> and gravity <span class="hlt">anomaly</span> data</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hinze, W. J.; Braile, L. W.; Vonfrese, R. R. B. (Principal Investigator); Keller, G. R.; Lidiak, E. G.</p> <p>1984-01-01</p> <p>Scalar <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> data from MAGSAT, reduced to vertical polarization and long wavelength pass filtered free air gravity <span class="hlt">anomaly</span> data of South America and the Caribbean are compared to major crustal features. The continental shields generally are more <span class="hlt">magnetic</span> than adjacent basins, oceans and orogenic belts. In contrast, the major aulacogens are characterized by negative <span class="hlt">anomalies</span>. Spherical earth <span class="hlt">magnetic</span> modeling of the Amazon River and Takatu aulacogens in northeastern South America indicates a less <span class="hlt">magnetic</span> crust associated with the aulacogens. Spherical earth modeling of both positive gravity and negative <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> observed over the Mississippi Embayment indicate the presence of a nonmagnetic zone of high density material within the lower crust associated with the aulacogen. The MAGSAT scalar <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> data and available free air gravity <span class="hlt">anomalies</span> over Euro-Africa indicate several similar relationships.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/37248','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/37248"><span id="translatedtitle">On the origin of <span class="hlt">magnetic</span> a.c. susceptibility non-SRT <span class="hlt">anomalies</span> in intermetallic compounds</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Bartolome, J.; Garcia, L.M.; Lazaro, F.J.; Grincourt, Y.; Fuente, L.G. de la; Francisco, C. de; Munoz, J.M.; Fruchart, D.</p> <p>1994-03-01</p> <p>The <span class="hlt">anomaly</span> detected in the <span class="hlt">magnetic</span> a.c. susceptibility of many intermetallic compounds between 100 and 300 K, and in particular in Nd{sub 2}Fe{sub 14}B at 220 K, has been induced in a controlled manner by thermal annealing. The <span class="hlt">anomaly</span> has been interpreted in terms of thermal activated processes of defects imposing their dynamical behavior on the domain walls coupled to them, thus solving the controversy on its origin.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_8 --> <div id="page_9" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="161"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19820016703','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19820016703"><span id="translatedtitle">The mineralogy of global <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>. [rock <span class="hlt">magnetic</span> signatures and MAGSAT geological, and gravity correlations in West Africa</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Haggerty, S. E. (Principal Investigator)</p> <p>1982-01-01</p> <p>Problems with the Curie balance, which severely hindered the acquisition of data, were rectified. Chemical analytical activities are proceeding satisfactorily. The <span class="hlt">magnetization</span> characteristics of metamorphic suites were analyzed and susceptibility data for a wide range of metamorphic and igneous rocks. These rock <span class="hlt">magnetic</span> signatures are discussed as well as the relationships between geology, gravity and MAGSAT <span class="hlt">anomalies</span> of West Africa.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002AGUSMGP41A..11F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002AGUSMGP41A..11F"><span id="translatedtitle">Soil <span class="hlt">Magnetism</span> and <span class="hlt">Magnetic</span> <span class="hlt">Anomalies</span> at the Marshall's Pen Archaeological Site, Mandeville, Jamaica</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Figueroa, E.; Sternberg, R. S.; Delle, J. A.; Lawrence, N. D.; McAdoo, B. G.; Savina, M. E.</p> <p>2002-05-01</p> <p>Marshall's Pen, a 1000-acre parcel of land in Mandeville, Jamaica, underlain by limestone bedrock and bauxite soils, served as a coffee plantation in the early 19th century. Two to three hundred slaves of African descent worked the plantation from AD 1802 until slavery was abolished in Jamaica in 1838. The goal of the archaeological program at Marshall's Pen is to complement what little is known about Jamaican slave society from the historical record. Geophysical prospection was conducted at Marshall's Pen by ten undergraduate students as part of a Keck Geology Consortium project in the summer of 1999. In the slaves' village consisting of living and domestic labor areas, G858 cesium vapor magnetometer readings were taken every 0.1 seconds along 49 profiles, each 50 m long and spaced 1 meter apart, and <span class="hlt">magnetic</span> susceptibility readings were taken at 1-meter intervals. Seven significant <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> (up to 100 nT peak-to-peak) were detected in the village. Two of these were found to be caused by a buried machete and an iron woodworking tool. Three <span class="hlt">anomalies</span> were associated with a large area of black, burned soil. Archaeological testing in this area produced partially carbonized seeds, charcoal, ceramics that were smudged after manufacture, and cutlery; this evidence suggests a domestic kitchen area. In situ susceptibility readings were zero on bedrock and low on the bauxite soils. Susceptibility readings generally correlated with the <span class="hlt">magnetics</span>, to values as high as 50 (x 10-6, volume specific SI) in the ``kitchen'' area, suggesting a source in the susceptibility contrast for these <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>. Soil samples were collected from the bauxite outside the village, and from the village area in the summer of 2001; ten village sites were sampled away from the kitchen area, and four from the kitchen area. Five samples from each site were boxed, weighed, and measured for laboratory susceptibility measurements. Eleven samples outide the village had a geometric mean susceptibility of 144 (x 10-8, mass-specific SI); forty-nine samples from the ten village off-kitchen sites had a mean susceptibility of 105; twenty samples from the four village on-kitchen sites had a mean susceptibility of 821. One sample from a village off-kitchen site had a susceptibility of 1894 due to the head of a roofing nail included in the sample. Isothermal remanent <span class="hlt">magnetization</span> experiments were carried out on one sample from most sites. Three samples from outside the village had ratios of IRM(0.1T)/IRM(1.0T) of 0.76, 0.5, and 0.74; ratios for ten samples from the village away from the kitchen were between 0.72-0.77; ratios for two samples from the village in the kitchen were more easily saturated with values of 0.90 and 1.0. The susceptibility and IRM results are consistent with reduction of hematite from sites outside the kitchen to magnetite or maghemite at sites within the kitchen area. The resulting higher susceptibilities could generate the <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> in this area.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22365552','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22365552"><span id="translatedtitle">A tale of two <span class="hlt">anomalies</span>: Depletion, dispersion, and the connection between the stellar lithium <span class="hlt">spread</span> and inflated radii on the pre-main sequence</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Somers, Garrett; Pinsonneault, Marc H. E-mail: pinsono@astronomy.ohio-state.edu</p> <p>2014-07-20</p> <p>We investigate lithium depletion in standard stellar models (SSMs) and main sequence (MS) open clusters, and explore the origin of the Li dispersion in young, cool stars of equal mass, age, and composition. We first demonstrate that SSMs accurately predict the Li abundances of solar analogs at the zero-age main sequence (ZAMS) within theoretical uncertainties. We then measure the rate of MS Li depletion by removing the [Fe/H]-dependent ZAMS Li pattern from three well-studied clusters, and comparing the detrended data. MS depletion is found to be mass-dependent, in the sense of more depletion at low mass. A dispersion in Li abundance at fixed T{sub eff} is nearly universal, and sets in by ∼200 Myr. We discuss mass and age dispersion trends, and the pattern is mixed. We argue that metallicity impacts the ZAMS Li pattern, in agreement with theoretical expectations but contrary to the findings of some previous studies, and suggest Li as a test of cluster metallicity. Finally, we argue that a radius dispersion in stars of fixed mass and age, during the epoch of pre-MS Li destruction, is responsible for the <span class="hlt">spread</span> in Li abundances and the correlation between rotation and Li in young cool stars, most well known in the Pleiades. We calculate stellar models, inflated to match observed radius <span class="hlt">anomalies</span> in <span class="hlt">magnetically</span> active systems, and the resulting range of Li abundances reproduces the observed patterns of young clusters. We discuss ramifications for pre-MS evolutionary tracks and age measurements of young clusters, and suggest an observational test.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19830013175','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19830013175"><span id="translatedtitle">MAGSAT investigation of crustal <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> in the eastern Indian Ocean</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Sailor, R. V.; Lazarewicz, A. R.</p> <p>1983-01-01</p> <p>Crustal <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> in a region of the eastern Indian Ocean were studied using data from NASA's MAGSAT mission. The investigation region (0 deg to 50 deg South, 75 to 125 deg East) contains several important tectonic features, including the Broken Ridge, Java Trench, Ninetyeast Ridge, and Southeast Indian Ridge. A large positive <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> is associated with the Broken Ridge and smaller positive <span class="hlt">anomalies</span> correlate with the Ninetyeast Ridge and western Australia. Individual profiles of scalar data (computed from vector components) were considered to determine the overall data quality and resolution capability. A set of MAGSAT ""Quiet-Time'' data was used to compute an equivalent source crustal <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> map of the study region. Maps of crustal <span class="hlt">magnetization</span> and <span class="hlt">magnetic</span> susceptibility were computed from the equivalent source dipoles. Gravity data were used to help interpretation, and a map of the ratio of <span class="hlt">magnetization</span> to density contrasts was computed using Poisson's relation. The results are consistent with the hypothesis of induced <span class="hlt">magnetization</span> of a crustal layer having varying thickness and composition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20030110662&hterms=Carnegie+Andrew&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3D%2528Carnegie%2BAndrew%2529','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20030110662&hterms=Carnegie+Andrew&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3D%2528Carnegie%2BAndrew%2529"><span id="translatedtitle">Why are There So Few <span class="hlt">Magnetic</span> <span class="hlt">Anomalies</span> in Martian Lowlands and Basins?</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Solomon, Sean C.; Aharonson, Oded; Banerdt, W. Bruce; Dombard, Andrew J.; Frey, Herbert V.; Golombek, Matthew P.; Hauck, Steven A., II; Head, James W., III; Johnson, Catherine L.; McGovern, Patrick J.</p> <p>2003-01-01</p> <p>The discovery of large areas of strongly <span class="hlt">magnetized</span> crust on Mars [1,2] provides important information on the timing of both crustal and deeper interior processes on that planet. Critical to an understanding of that timing, as well as to the processes that have contributed to the <span class="hlt">magnetization</span> and demagnetization of crustal materials, is the geographical distribution of <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> discernible from spacecraft orbit. The paucity of resolved <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> in the northern lowlands and within and surrounding the best-preserved major impact basins has been noted since the crustal field was first globally mapped [1], but no straightforward explanation of that full pattern has yet been offered. Here we suggest that ancient hydrothermal alteration of <span class="hlt">magnetic</span> carriers in Martian lowlands and basins may have contributed to the <span class="hlt">magnetization</span> distribution observed today.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JAESc..97..169G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JAESc..97..169G"><span id="translatedtitle">Study on crustal <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> and Curie surface in Southeast Tibet</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gao, Guoming; Kang, Guofa; Bai, Chunhua; Wen, Limin</p> <p>2015-01-01</p> <p>In this paper, the Potsdam model POMME-6.2 is used to investigate the distributions of crustal <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> and Curie surface in Southeast Tibet. The Curie surface is compared with the regional heat flow, Bouguer <span class="hlt">anomaly</span>, Moho depth, and seismicity. The results show that the <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> and Curie surface are both consistent with the geological structure. Sichuan Basin exhibits a high positive <span class="hlt">anomaly</span>, while orogenic belts such as the Longmenshan, northwestern Sichuan, and western Yunnan, exhibit weak positive or negative <span class="hlt">anomalies</span>. The distribution of <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> confirms that escape flow from east Tibet branches into northeastward part and southward part on west Sichuan Basin, due to resistance by the rigid basin. The depth of Curie surface ranges from 20 to 34 km. The Curie surface beneath the Longmenshan, Xiaojiang and Lijiang-Xiaojinhe faults is shallow, with the uplift strike consistent with the faults. The Curie surface beneath Sichuan Basin and the central Bayan Har massif is deep, with sheet-like depressions. Strong earthquakes primarily occurred in the areas with the uplift of Curie surface. The heat flow values near Tengchong, Lijiang, Dali and Kunming are high and the Curie surface there is shallow.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19850044258&hterms=Curie&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DCurie','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19850044258&hterms=Curie&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DCurie"><span id="translatedtitle">A review of problems and progress in studies of satellite <span class="hlt">magnetic</span> <span class="hlt">anomalies</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mayhew, M. A.; Johnson, B. D.; Wasilewski, P. J.</p> <p>1985-01-01</p> <p>A review is conducted of studies performed during the Magsat project. The obtained data are considered, taking into account questions of data availability, aspects of orbit attitude determination, ionospheric noise, a field model, and an <span class="hlt">anomaly</span> field presentation. Models for interpretation are discussed, giving attention to forward modeling, and equivalent layer inverse modeling. In an evaluation of rock property constraints, the <span class="hlt">magnetic</span> bottom is discussed along with Curie points, metamorphism and <span class="hlt">magnetization</span>, and the direction of <span class="hlt">magnetization</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.P31A1700D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.P31A1700D"><span id="translatedtitle">The Smoking Gun: Remanent <span class="hlt">Magnetic</span> <span class="hlt">Anomalies</span> on Mars and the Formation of the Crustal Dichotomy via Giant Impact</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dombard, A. J.; Johnson, C. L.</p> <p>2011-12-01</p> <p>The formation of large-scale crustal <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> in the Southern Highlands of Mars is equivocal. Though some are indeed elongated primarily in the east-west direction, initial map projections exacerbated their linear nature, leading to the hypothesis that the <span class="hlt">anomalies</span> are equivalent to <span class="hlt">magnetic</span> stripes due to <span class="hlt">spreading</span> of Earth's sea floor and hence to the proposal of plate tectonics on Mars. This interpretation, however, is inconsistent with Martian geology. For instance, a plate-tectonics model predicts the <span class="hlt">anomalies</span> should be formed in thin, oceanic crust at low elevation, but instead they are found in the thick crust of the Highlands, not in the thin crust of the Northern Lowlands. Indeed, the formation of this Crustal Dichotomy is also equivocal, with models ranging from a giant impact (or multiple smaller impacts) near either the current north or south poles, to plate tectonics-like processes, to mantle convection, either eroding the crust in the northern hemisphere or thickening the crust in the south. Recently, the idea of a giant impact in the north has been resurrected, with the proposal that the Dichotomy results from the formation of an elliptical basin by a giant impact very early in Martian history. While it may be tempting to suggest that the current, generally demagnetized state of the Northern Lowlands may be related to this impact, this linkage makes implicit assumptions about the timing of dynamo shut-off on Mars, and it neglects other demagnetization mechanisms possibly operating in the Lowlands after such an impact (e.g., later hydrothermal processing). More direct <span class="hlt">magnetic</span> evidence for the giant impact hypothesis would come if the remanent <span class="hlt">magnetism</span> in Southern Highlands were relatable in a unique way to the putative impact. Here, we show that the positions of many of the dominant elongated <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> on Mars are consistent with the first ring of a multi-ring basin. The best match comes from an ellipse ~2200 km wider than the inferred boundary of the basin. This distance is the square root of 2 minus 1 of the long axis, and root-2 spacing is characteristic of the inward dipping normal faults in multi-ring basins. The constant distance of our predicted ring, as opposed to variable spacing due to the elliptical nature of the basin, is also consistent with the idea that multi-ring basins form from stress release during inward collapse of the transient crater. Because of the size of the basin, the second ring would be found in the antipodal region, where its formation is dubious and where seismic focusing from the impact has been proposed to explain the generally absent <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> in the south polar region. The observation that the elongated <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> on Mars mark the first ring around a basin both provides an explanation for the formation of many of the <span class="hlt">anomalies</span>, and supports the hypothesis that the Crustal Dichotomy of Mars is the product of a giant impact that formed an elliptical basin.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19810017984','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19810017984"><span id="translatedtitle">Gravity and <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> modeling and correlation using the SPHERE program and Magsat data</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Braile, L. W.; Hinze, W. J. (Principal Investigator); Vonfrese, R. R. B.</p> <p>1980-01-01</p> <p>The spherical Earth inversion, modeling, and contouring software were tested and modified for processing data in the Southern Hemisphere. Preliminary geologic/tectonic maps and selected cross sections for South and Central America and the Caribbean region are being compiled and as well as gravity and <span class="hlt">magnetic</span> models for the major geological features of the area. A preliminary gravity model of the Andeas Beniff Zone was constructed so that the density columns east and west of the subducted plates are in approximate isostatic equilibrium. The <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> for the corresponding <span class="hlt">magnetic</span> model of the zone is being computed with the SPHERE program. A test tape containing global <span class="hlt">magnetic</span> measurements was converted to a tape compatible with Purdue's CDC system. NOO data were screened for periods of high diurnal activity and reduced to <span class="hlt">anomaly</span> form using the IGS-75 model. <span class="hlt">Magnetic</span> intensity <span class="hlt">anomaly</span> profiles were plotted on the conterminous U.S. map using the track lines as the <span class="hlt">anomaly</span> base level. The transcontinental <span class="hlt">magnetic</span> high seen in POGO and MAGSAT data is also represented in the NOO data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014Tectp.624...15F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014Tectp.624...15F"><span id="translatedtitle">Craton vs. rift uppermost mantle contributions to <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> in the United States interior</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Friedman, S. A.; Feinberg, J. M.; Ferré, E. C.; Demory, F.; Martín-Hernández, F.; Conder, J. A.; Rochette, P.</p> <p>2014-06-01</p> <p>The interpretation of satellite <span class="hlt">magnetic</span> information (Magsat, Oersted, CHAMP, Swarm) requires the understanding of the mineralogy of crustal and mantle sources. Also, spectral analysis of <span class="hlt">magnetic</span> data over forearcs and cratons calls for upper mantle contribution. The prospect of such a contribution contradicts the view that the mantle is too hot and its <span class="hlt">magnetism</span> is too weak to influence <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>. Here we examine the rock <span class="hlt">magnetic</span> properties of fresh mantle xenoliths from four settings across the United States: phlogopite-spinel dunites from the Bearpaw Mountains, Montana, and lherzolites/harzburgites from San Carlos, Arizona; Kilbourne Hole, New Mexico; and Knippa, Texas. Paleomagnetic results show single-component natural remanent <span class="hlt">magnetizations</span> (NRMs), which, combined with optical and secondary electron microscopy support the lack of post-eruption alteration and absence of host-rock contamination. The NRM carriers include magnetite at Bearpaw Mountain and San Carlos, and pyrrhotite at Kilbourne Hole and Knippa. These four areas show continental crust of distinct thicknesses and various geotherms. The potential mantle contribution to <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> is forward modeled using crustal thickness, current geotherm and average <span class="hlt">magnetic</span> properties of xenoliths. The San Carlos and Kilbourne Hole mantle, situated near the Rio Grande Rift is too hot and its <span class="hlt">magnetism</span> is too weak to contribute to <span class="hlt">anomalies</span>. The sulfide-dominated assemblage at Knippa does not support <span class="hlt">magnetization</span> at mantle depths. In contrast, the Bearpaw Mountains combine a relatively cold geotherm (craton) and abundance of magnetite formed at mantle depth. This cratonic mantle, metasomatized by fluids from the Farallon plate, may contribute to long wavelength <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFMGP41A0991S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFMGP41A0991S"><span id="translatedtitle">Processing and Analysis of Near-Seafloor <span class="hlt">Magnetic</span> <span class="hlt">Anomalies</span> around Futuna Island, SW Pacific Ocean</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Szitkar, F.; Dyment, J.; Fouquet, Y.; Choi, Y.</p> <p>2011-12-01</p> <p>In September 2010, cruise Futuna of R/V L'Atalante collected near-seafloor <span class="hlt">magnetic</span> data with AUV Aster-X (70 m asf) and Deep-Sea Submersible (DSS) Nautile (2-20 m asf) on several volcanic systems around Futuna Island, SW Pacific Ocean. Here we present the data, the method of analysis, and a first geological interpretation. Unlike a ship, a submersible (or an AUV) cannot tow a magnetometer due to the close proximity of the seafloor. Instead, the magnetometer is rigidly fixed on the submersible, which <span class="hlt">magnetization</span> affects the <span class="hlt">magnetic</span> measurements. A vector magnetometer (i.e. three orthogonal fluxgate sensors) measures the field three components in a referential linked to the submarine, a requirement to determine and correct the <span class="hlt">magnetization</span> of the submersible, The remanent <span class="hlt">magnetization</span> vector (3 components) and the <span class="hlt">magnetic</span> susceptibility tensor (9 coefficients) of the submersible are estimated by inverting <span class="hlt">magnetic</span> data collected on calibration loops, far from both the ship and the seafloor, during the descent (ascent) of the submersible at the beginning (end) of the dives. For this estimation, the ambient field is assumed to be the IGRF, the departures from this assumption reflecting the <span class="hlt">magnetization</span> of the submersible. The twelve coefficients are inverted from the loop data by a least square method, regularized by a dumping factor to account for the limited pitch and roll values sampled by the submersible. Once determined, these coefficients are used to reduce the <span class="hlt">magnetic</span> data acquired during the whole dive for the <span class="hlt">magnetic</span> effect of the submersible, the resulting three component <span class="hlt">anomalies</span> being rotated to the geographic reference frame as well. The resulting <span class="hlt">anomalies</span> acquired by the AUV on regularly-spaced tracks are gridded and reduced to the pole such as the resulting <span class="hlt">anomalies</span> are located on the top of their causative sources. They are further inverted to equivalent <span class="hlt">magnetization</span> using the high-resolution topography acquired by the AUV. The <span class="hlt">anomalies</span> acquired by DSS Nautile on isolated and uneven tracks are cut and projected on linear segments. Synthetic <span class="hlt">anomalies</span> are computed under the conditions of the experiment, assuming a unit <span class="hlt">magnetization</span>. Observed and computed <span class="hlt">anomalies</span> are compared on sliding windows, resulting in an estimate of the absolute <span class="hlt">magnetization</span> of the seafloor. The data sets collected at 2-20 m (by DSS Nautile) and 70 m (by AUV Aster-X) jointly constrain the geological interpretation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFMSM13D2103I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFMSM13D2103I"><span id="translatedtitle">Vlasov Simulation of the Interaction Between the Solar Wind and a Dielectric Body with <span class="hlt">Magnetic</span> <span class="hlt">Anomaly</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ito, Y.; Umeda, T.; Ogino, T.</p> <p>2011-12-01</p> <p>The interaction of a plasma flow with an unmagnetized object is quite different from that with a <span class="hlt">magnetized</span> object such as the Earth. Due to the absence of the global <span class="hlt">magnetic</span> field, the unmagnetized object absorbs plasma particles which reach the surface, generating a plasma cavity called wake in the anti-solar side of the object. Since the velocity of the solar wind (SW) is larger than the thermal velocity of ions, ions cannot penetrate into the nightside of the moon. However, ions were observed in the deep wake by a Japanese spacecraft KAGUYA (SELENE) which is orbiting the moon in a polar orbit around 100km altitude. A key mechanism of this phenomenon is thought to be scattering of SW ions at the lunar dayside surface by an interaction between the Interplanetary <span class="hlt">Magnetic</span> Field (IMF) and a lunar <span class="hlt">magnetic</span> <span class="hlt">anomaly</span>. In the present study, we examine structure of the wake due to the interaction between IMF and the <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> via a full-kinetic Vlasov simulation. We performed one of the first global Vlasov simulations of magnetosphere. We assumed a 2.5D Cartesian system in which spatial grids are taken in the 2D plane and velocity grids are taken in 3D space. There exists an insulative sphere, in which the charge accumulates at the surface. The intrinsic <span class="hlt">magnetic</span> field of the object as the <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> is assumed to be the 2D dipole <span class="hlt">magnetic</span> field. The solar wind also carries an IMF. The simulation results suggest that the <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> on the dayside surface of the moon would affect to the formation of the wake field. The structure of plasma void is modified by the convection of <span class="hlt">magnetic</span> field motion.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.P43F..06W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.P43F..06W"><span id="translatedtitle">Laboratory studies of <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> effects on electric potential distributions near the lunar surface</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, X.; Robertson, S. H.; Horanyi, M.; NASA Lunar Science Institute: Colorado CenterLunar Dust; Atmospheric Studies</p> <p>2011-12-01</p> <p>The Moon does not have a global <span class="hlt">magnetic</span> field, unlike the Earth, rather it has strong crustal <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>. Data from Lunar Prospector and SELENE (Kaguya) observed strong interactions between the solar wind and these localized <span class="hlt">magnetic</span> fields. In the laboratory, a configuration of a horseshoe permanent <span class="hlt">magnet</span> below an insulating surface is used as an analogue of lunar crustal <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>. Plasmas are created above the surface by a hot filament discharge. Potential distributions are measured with an emissive probe and show complex spatial structures. In our experiments, electrons are <span class="hlt">magnetized</span> with gyro-radii r smaller than the distance from the surface d (r < d) and ions are un-<span class="hlt">magnetized</span> with r > d. Unlike negative charging on surfaces with no <span class="hlt">magnetic</span> fields, the surface potential at the center of the <span class="hlt">magnetic</span> dipole is found close to the plasma bulk potential. The surface charging is dominated by the cold unmagnetized ions, while the electrons are shielded away. A potential minimum is formed between the center of the surface and the bulk plasma, most likely caused by the trapped electrons between the two <span class="hlt">magnetic</span> mirrors at the cusps. The value of the potential minimum with respect to the bulk plasma potential decreases with increasing plasma density and neutral pressure, indicating that the mirror-trapped electrons are scattered by electron-electron and electron-neutral collisions. The potential at the two cusps are found to be more negative due to the electrons following the <span class="hlt">magnetic</span> field lines onto the surface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012CG.....39..135S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012CG.....39..135S"><span id="translatedtitle">Magan: A new approach to the analysis and interpretation of marine <span class="hlt">magnetic</span> <span class="hlt">anomalies</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schettino, Antonio</p> <p>2012-02-01</p> <p>The identification of marine <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> is an important phase of plate tectonic modeling, but is limited by the lack of professional software, either free or commercial, which may help in the accomplishment of this task, and by the practice of performing approximations that may prevent in some instances a correct interpretation of the <span class="hlt">magnetic</span> data. Although basic forward-modeling and inversion algorithms that may be incorporated in the core of gravity or <span class="hlt">magnetic</span> application software have been published since the late 1950s, most research groups have implemented their own tools independently from each other, and apart from a few cases such computer programs are not publicly accessible. Here a new methodology of analysis of marine <span class="hlt">magnetic</span> data is described, which allows a quantitative correlation of <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> from different profiles and a statistical determination of relative plate velocities. The method is implemented through a new free software package, Magan, available for the MS Windows environment. The program is especially designed to work with NGDC GEODAS ship-track and aeromagnetic data, but allows the import of any ASCII text file containing <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> data. The basic forward-modeling algorithms included in the Magan core are based on well-known techniques of potential field geophysics, modified to take into account specific requirements of marine <span class="hlt">magnetic</span> data analysis and plate tectonic modeling. Such a kernel is flanked by a friendly graphical user interface (GUI), which helps and speeds up the interpretation of the ship-track data. In particular, the program allows one to (1) draw and edit flow lines where <span class="hlt">magnetic</span> data can be projected, (2) calculate more accurately modeled <span class="hlt">anomalies</span> through the use of apparent polar wander paths and single block parameters, (3) generate age-distance and time-velocity graphs, and (4) generate crossing point files that can be subsequently used to build <span class="hlt">magnetic</span> isochrons.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ApGeo..13...59F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ApGeo..13...59F"><span id="translatedtitle">Regional <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> fields: 3D Taylor polynomial and surface spline models</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Feng, Yan; Jiang, Yong; Jiang, Yi; Li, Zheng; Jiang, Jin; Liu, Zhong-Wei; Ye, Mei-Chen; Wang, Hong-Sheng; Li, Xiu-Ming</p> <p>2016-03-01</p> <p>We used data from 1960.0, 1970.0, 1980.0, 1990.0, and 2000.0 to study the geomagnetic <span class="hlt">anomaly</span> field over the Chinese mainland by using the three-dimensional Taylor polynomial (3DTP) and the surface spline (SS) models. To obtain the pure <span class="hlt">anomaly</span> field, the main field and the induced field of the ionospheric and magnetospheric fields were removed from measured data. We also compared the SS model <span class="hlt">anomalies</span> and the data obtained with Kriging interpolation (KI). The geomagnetic <span class="hlt">anomaly</span> distribution over the mainland was analyzed based on the SS and 3DTP models by transferring all points from 1960.0-1990.0 to 2000.0. The results suggest that the total intensity F <span class="hlt">anomalies</span> estimated based on the SS and KI for each year are basically consistent in distribution and intensity. The anomalous distributions in the X-, Y-, and Z-direction and F are mainly negative. The 3DTP model <span class="hlt">anomalies</span> suggest that the intensity in the X-direction increases from -100 nT to 0 nT with longitude, whereas the intensity in the Y-direction decreases from 400 nT to 20 nT with longitude and over the eastern mainland is almost negative. The intensity in the Z-direction and F are very similar and in most areas it is about -50nT and higher in western Tibet. The SS model <span class="hlt">anomalies</span> overall reflect the actual distribution of the <span class="hlt">magnetic</span> field <span class="hlt">anomalies</span>; however, because of the uneven distribution of measurements, it yields several big <span class="hlt">anomalies</span>. Owing to the added altitude term, the 3DTP model offers higher precision and is consistent with KI.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011SSCom.151..564K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011SSCom.151..564K"><span id="translatedtitle">Temperature-dependent <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> of CuO nanoparticles</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Karthik, K.; Victor Jaya, N.; Kanagaraj, M.; Arumugam, S.</p> <p>2011-04-01</p> <p>Copper oxide (CuO) nanoparticles with an average size of 25 nm were prepared by a sol-gel method. A detailed study was made of the <span class="hlt">magnetization</span> of CuO nanoparticles using a maximum field of 60 kOe for temperatures between 8 and 300 K. Antiferromagnetic CuO nanoparticles exhibit anomalous <span class="hlt">magnetic</span> properties, such as enhanced coercivity and <span class="hlt">magnetic</span> moments. Significantly, the magnitude of the hysteresis component tends to weaken upon increase in temperature (>8 K). In addition, a hysteresis loop shift and coercivity enhancement are observed at 8 K in the field-cooled (FC, at 50 kOe) case. It is thought that the change in hysteresis behavior is due to the uncompensated surface spins of the CuO nanoparticles. The susceptibility ( ?) plot showed that ? varied substantially at temperatures below 12 K, and this transition is due to the exchange interactions between the neighboring atoms at the nanoscale.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009Tectp.478..119M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009Tectp.478..119M"><span id="translatedtitle">Remanent and induced <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> over a layered intrusion: Effects from crystal fractionation and magma recharge</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>McEnroe, Suzanne A.; Brown, Laurie L.; Robinson, Peter</p> <p>2009-12-01</p> <p>The Bjerkreim-Sokndal (BKS) norite - quartz mangerite layered intrusion is part of the early Neoproterozoic Rogaland Anorthosite Province intruded into the Fennoscandian shield in south Norway at ~ 930 Ma. The BKS is exposed over an area of 230 km 2 with a thickness of ~ 7000 m and is of economic interest for ilmenite, magnetite and apatite deposits. From the point of view of <span class="hlt">magnetic</span> minerals, in the course of fractional crystallization and magma evolution, the ilmenite becomes less Fe 3+-rich reflected by a change from ilmenite with hematite exsolution to nearly pure ilmenite. Magnetite starts to crystallize relatively late in the intrusive history, but its crystallization is interrupted by influxes of more primitive magma. The variations in aeromagnetic and ground-<span class="hlt">magnetic</span> <span class="hlt">anomalies</span> measured over the BKS can be explained in terms of the measured <span class="hlt">magnetic</span> properties of NRM, susceptibility, and hysteresis presented here, and in terms of mineralogy. Early layers in the intrusion contain hemo-ilmenite. As the magma evolved and magnetite started to crystallize, this caused a distinct change over the layering from remanence-controlled negative <span class="hlt">anomalies</span> to induced positive <span class="hlt">anomalies</span>. When new, more primitive magma was injected into the system, hemo-ilmenite returned as the major oxide and the resulting <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> are again negative. The most dramatic change in the <span class="hlt">magnetic</span> signature is in the upper part of the intrusion in MCU IVe, where magnetite became a well established cumulate phase as indicated by susceptibility, but its induced <span class="hlt">magnetization</span> is overcome by large NRMs associated either with hemo-ilmenite, or with hemo-ilmenite and magnetite exsolved from pyroxenes. The average natural remanent <span class="hlt">magnetizations</span> change from ~ 3 A/m in MCU IVd, to 15 A/m in MCU IVe, and back to 2 A/m in the overlying MCU IVf, producing a strong negative remanent <span class="hlt">anomaly</span> that has been followed along strike for at least 20 km by ground-<span class="hlt">magnetic</span> measurements. The highly varied <span class="hlt">magnetic</span> properties of this intrusion, caused by varied magmatic crystallization of combinations of opaque minerals, illustrate some of the possibilities to be considered in evaluating crustal <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016MeScT..27d5104S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016MeScT..27d5104S"><span id="translatedtitle"><span class="hlt">Magnetic</span> <span class="hlt">anomaly</span> detection (MAD) of ferromagnetic pipelines using principal component analysis (PCA)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sheinker, Arie; Moldwin, Mark B.</p> <p>2016-04-01</p> <p>The <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> detection (MAD) method is used for detection of visually obscured ferromagnetic objects. The method exploits the <span class="hlt">magnetic</span> field originating from the ferromagnetic object, which constitutes an <span class="hlt">anomaly</span> in the ambient earth’s <span class="hlt">magnetic</span> field. Traditionally, MAD is used to detect objects with a <span class="hlt">magnetic</span> field of a dipole structure, where far from the object it can be considered as a point source. In the present work, we expand MAD to the case of a non-dipole source, i.e. a ferromagnetic pipeline. We use principal component analysis (PCA) to calculate the principal components, which are then employed to construct an effective detector. Experiments conducted in our lab with real-world data validate the above analysis. The simplicity, low computational complexity, and the high detection rate make the proposed detector attractive for real-time, low power applications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20000080790&hterms=volcanism&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dvolcanism','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20000080790&hterms=volcanism&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dvolcanism"><span id="translatedtitle">Hydrology in the Durius Valles Region: Evaluation of Possible Correlation with Volcanism and <span class="hlt">Magnetic</span> <span class="hlt">Anomalies</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Cabrol, Natalie A.; Marinangeli, Lucia; Grin, Edmond A.</p> <p>2000-01-01</p> <p>We envision the contribution of subglacial flows, hydrothermalism and sapping in the Durius Valles system and the consequences in term of climate on Mars in recent geological times. We evaluate the possible correlation of the hydrology with volcanism and <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110007825','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110007825"><span id="translatedtitle">Lunar Ion Transport Near <span class="hlt">Magnetic</span> <span class="hlt">Anomalies</span>: Possible Implications for Swirl Formation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Keller, J. W.; Killen, R. M.; Stubbs, T. J.; Farrell, W. M.; Halekas, J. S.</p> <p>2011-01-01</p> <p>The bright swirling features on the lunar surface in areas around the Moon but most prominently at Reiner Gamma, have intrigued scientists for many years. After Apollo and later Lunar Prospector (LP} mapped the Lunar <span class="hlt">magnetic</span> fields from orbit, it was observed that these features are generally associated with crustal <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>. This led researchers to propose a number of explanations for the swirls that invoke these fields. Prominent among these include <span class="hlt">magnetic</span> shielding in the form of a mini-magnetosphere which impedes space weathering by the solar wind, <span class="hlt">magnetically</span> controlled dust transport, and cometary or asteroidal impacts that would result in shock <span class="hlt">magnetization</span> with concomitant formation ofthe swirls. In this presentation, we will consider another possibility, that the ambient <span class="hlt">magnetic</span> and electric fields can transport and channel secondary ions produced by micrometeorite or solar wind ion impacts. In this scenario, ions that are created in these impacts are under the influence of these fields and can drift for significant distances before encountering the <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> when their trajectories are disrupted and concentrated onto nearby areas. These ions may then be responsible for chemical alteration of the surface leading either to a brightening effect or a disruption of space weathering processes. To test this hypothesis we have run ion trajectory simulations that show ions from regions about the <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> can be channeled into very small areas near the <span class="hlt">anomalies</span> and although questions remain as to nature of the mechanisms that could lead to brightening of the surface it appears that the channeling effect is consistent with the existence of the swirls.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_9 --> <div id="page_10" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="181"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.T31B2585L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.T31B2585L"><span id="translatedtitle">Thermal evolution of the North Atlantic lithosphere constrained by Curie depths from <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> inversion</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Li, C.; Wang, J.; Lin, J.; Wang, T.</p> <p>2012-12-01</p> <p>Detecting lithospheric geotherms in the ocean basins proves very difficult currently with only low-resolution seismic tomography and sparsely and irregularly spaced heat flow measurements. Forward numerical modeling of oceanic lithospheric cooling cannot incorporate complex local variations. Here using recently published global compilations of <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>, we present the first effort in providing additional and independent constraints on geothermal state and mantle dynamics of the North Atlantic lithosphere from <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> inversion with a fractal <span class="hlt">magnetization</span> model. Two theoretical models of radial spectrum of <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> are found almost identical, and both are applicable to detecting Curie depths in using the centroid method that is based on linearization at certain wavenumber bands. Both theoretical and numerical studies confirm the robustness of this inversion scheme. A constant fractal exponent of 3 is found suitable for the study area, and the estimated Curie depths are very well constrained by known depths near the mid-Atlantic ridge. While generally increasing in depths with growing ages, Curie points show large oscillating and heterogeneous patterns related most likely to small scale sublithospheric convections. Hotspots also contribute significantly a large spectrum of geothermal and Curie-depth <span class="hlt">anomalies</span> but they appear to connect more closely to geochemical <span class="hlt">anomalies</span> or upwelling small-scale convective cells than to mantle plumes. These identified geothermal <span class="hlt">anomalies</span> from Curie depths are confirmed by their good correlations to similar features in gridded heat flow map, which bears larger geodynamic significance than original raw heat flow measurements. The Curie depth versus heat flow plot also suggests decreasing effective thermal conductivities roughly from around 3.0 W/(m °C) to around 2.0 W/(m °C) with increasing depths within the <span class="hlt">magnetic</span> layer. The fact that most Curie points are located beneath the Moho in North Atlantic suggests that the uppermost mantle is also <span class="hlt">magnetized</span> from serpentinization, inducing both long-wavelength <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> and apparent flattening and deviations in heat flow and bathymetry from the half-space cooling model.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PEPI..253...74M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PEPI..253...74M"><span id="translatedtitle">Three-dimensional inverse modelling of <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> sources based on a genetic algorithm</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Montesinos, Fuensanta G.; Blanco-Montenegro, Isabel; Arnoso, José</p> <p>2016-04-01</p> <p>We present a modelling method to estimate the 3-D geometry and location of homogeneously <span class="hlt">magnetized</span> sources from <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> data. As input information, the procedure needs the parameters defining the <span class="hlt">magnetization</span> vector (intensity, inclination and declination) and the Earth's <span class="hlt">magnetic</span> field direction. When these two vectors are expected to be different in direction, we propose to estimate the <span class="hlt">magnetization</span> direction from the <span class="hlt">magnetic</span> map. Then, using this information, we apply an inversion approach based on a genetic algorithm which finds the geometry of the sources by seeking the optimum solution from an initial population of models in successive iterations through an evolutionary process. The evolution consists of three genetic operators (selection, crossover and mutation), which act on each generation, and a smoothing operator, which looks for the best fit to the observed data and a solution consisting of plausible compact sources. The method allows the use of non-gridded, non-planar and inaccurate <span class="hlt">anomaly</span> data and non-regular subsurface partitions. In addition, neither constraints for the depth to the top of the sources nor an initial model are necessary, although previous models can be incorporated into the process. We show the results of a test using two complex synthetic <span class="hlt">anomalies</span> to demonstrate the efficiency of our inversion method. The application to real data is illustrated with aeromagnetic data of the volcanic island of Gran Canaria (Canary Islands).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19800009265','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19800009265"><span id="translatedtitle">Comparison of <span class="hlt">Magnetic</span> <span class="hlt">Anomalies</span> of Lithospheric Origin Measured by Satellite and Airborne Magnetometers over Western Canada</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Langel, R. A.; Coles, R. L.; Mayhew, M. A.</p> <p>1979-01-01</p> <p>Crustal <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> data from the OGO 2, 4 and 6 (Pogo) satellites are compared with upward-continued aeromagnetic data between 50 deg -85 deg N latitude and 220 deg - 260 deg E longitude. Agreement is good both in <span class="hlt">anomaly</span> location and in amplitude, giving confidence that it is possible to proceed with the derivation and interpretation of satellite <span class="hlt">anomaly</span> maps in all parts of the globe. The data contain a <span class="hlt">magnetic</span> high over the Alpha ridge suggesting continental composition and a <span class="hlt">magnetic</span> low over the southern Canada basin and northern Canadian Arctic islands (Sverdrup basin). The low in the Sverdrup basin corresponds to a region of high heat flow, suggesting a shallow Curie isotherm. A ridge of high field, with two distinct peaks in amplitude, is found over the northern portion of the platform deposits and a relative high is located in the central portion of the Churchill province. No features are present to indicate a <span class="hlt">magnetic</span> boundary between Slave and Bear provinces, but a trend change is evident between Slave and Churchill provinces. South of 60 deg latitude a broad <span class="hlt">magnetic</span> low is located over very thick (40-50 km) crust, interpreted to be a region of low <span class="hlt">magnetization</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..12.6000S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..12.6000S"><span id="translatedtitle">Interaction between Solar Wind and Lunar <span class="hlt">Magnetic</span> <span class="hlt">Anomalies</span> observed by Kaguya MAP-PACE</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Saito, Yoshifumi; Yokota, Shoichiro; Tanaka, Takaaki; Asamura, Kazushi; Nishino, Masaki; Yamamoto, Tadateru; Uemura, Kota; Tsunakawa, Hideo</p> <p>2010-05-01</p> <p>It is known that Moon has neither global intrinsic <span class="hlt">magnetic</span> field nor thick atmosphere. Different from the Earth's case where the intrinsic global <span class="hlt">magnetic</span> field prevents the solar wind from penetrating into the magnetosphere, solar wind directly impacts the lunar surface. Since the discovery of the lunar crustal <span class="hlt">magnetic</span> field in 1960s, several papers have been published concerning the interaction between the solar wind and the lunar <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>. MAG/ER on Lunar Prospector found heating of the solar wind electrons presumably due to the interaction between the solar wind and the lunar <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> and the existence of the mini-magnetosphere was suggested. However, the detailed mechanism of the interaction has been unclear mainly due to the lack of the in-situ observed data of low energy ions. <span class="hlt">MAgnetic</span> field and Plasma experiment - Plasma energy Angle and Composition Experiment (MAP-PACE) on Kaguya (SELENE) completed its ˜1.5-year observation of the low energy charged particles around the Moon on 10 June, 2009. Kaguya was launched on 14 September 2007 by H2A launch vehicle from Tanegashima Space Center in Japan. Kaguya was inserted into a circular lunar polar orbit of 100km altitude and continued observation for nearly 1.5 years till it impacted the Moon on 10 June 2009. During the last 5 months, the orbit was lowered to ˜50km-altitude between January 2009 and April 2009, and some orbits had further lower perilune altitude of ˜10km after April 2009. MAP-PACE consisted of 4 sensors: ESA (Electron Spectrum Analyzer)-S1, ESA-S2, IMA (Ion Mass Analyzer), and IEA (Ion Energy Analyzer). All the sensors performed quite well as expected from the laboratory experiment carried out before launch. Since each sensor had hemispherical field of view, two electron sensors and two ion sensors that were installed on the spacecraft panels opposite to each other could cover full 3-dimensional phase space of low energy electrons and ions. One of the ion sensors IMA was an energy mass spectrometer. IMA measured mass identified ion energy spectra that had never been obtained at 100km altitude polar orbit around the Moon. When Kaguya flew over South Pole Aitken region, where strong <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> exist, solar wind ions reflected by <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> were observed. These ions had much higher flux than the solar wind protons scattered at the lunar surface. The <span class="hlt">magnetically</span> reflected ions had nearly the same energy as the incident solar wind ions while the solar wind protons scattered at the lunar surface had slightly lower energy than the incident solar wind ions. At 100km altitude, when the reflected ions were observed, the simultaneously measured electrons were often heated and the incident solar wind ions were sometimes slightly decelerated. At ~50km altitude, when the reflected ions were observed, proton scattering at the lunar surface clearly disappeared. It suggests that there exists an area on the lunar surface where solar wind does not impact. At ~10km altitude, the interaction between the solar wind ions and the lunar <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> was remarkable with clear deceleration of the incident solar wind ions and heating of the reflected ions as well as significant heating of the electrons. Calculating velocity moments including density, velocity, temperature of the ions and electrons, we have found that there exists 100km scale regions over strong <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> where plasma parameters are quite different from the outside. Solar wind ions observed at 10km altitude show several different behaviors such as deceleration without heating and heating in a limited region inside the <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> that may be caused by the <span class="hlt">magnetic</span> field structure. The deceleration of the solar wind has the same ΔE/q (ΔE : deceleration energy, q: charge) for different species, which constraints the possible mechanisms of the interaction between solar wind and <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhRvD..92l5031H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhRvD..92l5031H"><span id="translatedtitle">Self-similar inverse cascade of <span class="hlt">magnetic</span> helicity driven by the chiral <span class="hlt">anomaly</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hirono, Yuji; Kharzeev, Dmitri E.; Yin, Yi</p> <p>2015-12-01</p> <p>For systems with charged chiral fermions, the imbalance of chirality in the presence of <span class="hlt">magnetic</span> field generates an electric current—this is the chiral <span class="hlt">magnetic</span> effect (CME). We study the dynamical real-time evolution of electromagnetic fields coupled by the <span class="hlt">anomaly</span> to the chiral charge density and the CME current by solving the Maxwell-Chern-Simons equations. We find that the CME induces the inverse cascade of <span class="hlt">magnetic</span> helicity toward the large distances, and that at late times this cascade becomes self-similar, with universal exponents. We also find that in terms of gauge field topology the inverse cascade represents the transition from linked electric and <span class="hlt">magnetic</span> fields (Hopfions) to the knotted configuration of <span class="hlt">magnetic</span> field (Chandrasekhar-Kendall states). The <span class="hlt">magnetic</span> reconnections are accompanied by the pulses of the CME current directed along the <span class="hlt">magnetic</span> field lines. We devise an experimental signature of these phenomena in heavy ion collisions, and speculate about implications for condensed matter systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.P41F1987Q','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.P41F1987Q"><span id="translatedtitle">New Clues on the Source of the Central <span class="hlt">Magnetic</span> <span class="hlt">Anomaly</span> at Haughton Impact Structure, Canada</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Quesnel, Y.; Rochette, P.; Gattacceca, J.; Osinski, G. R.</p> <p>2013-12-01</p> <p>The 23 km-diameter Haughton impact structure, located on Devon Island, Nunavut, Canada, is one of the best-preserved medium-size complex impact structures on Earth. The impact occurred ~39 Ma ago into a target formation composed of an ~2-km thick sequence of Lower Paleozoic sedimentary rocks of the Arctic Platform overlying Precambrian metamorphic basement of the Canadian Shield (Osinski et al., 2005). Clast-rich carbonate impact melt rocks fill the crater and impact-generated hydrothermal activity took place, but since then no significant geological event has affected the area. A 900 nT-amplitude <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> with a wavelength of about 3 km is observed at the center of the crater (Pohl et al., 1988). Using high-resolution ground <span class="hlt">magnetic</span> survey and <span class="hlt">magnetic</span> property measurements on rock samples from inside and outside the structure, Quesnel et al. (2013) concluded that the source for this <span class="hlt">anomaly</span> may correspond to uplifted and hydrothermally-aletered basement rocks. Hydrothermal activity can increase rock <span class="hlt">magnetization</span> intensity by crystallization of <span class="hlt">magnetic</span> minerals, such as magnetite and/or pyrrhotite. Here, we present the results of a new ground <span class="hlt">magnetic</span> survey and electrical resistivity soundings conducted around the maximum of the <span class="hlt">magnetic</span> <span class="hlt">anomaly</span>. Drilling, with depths ranging from 5 m to 13 m was also conducted at three locations in the same area to ground truth the interpretation of geophysical data. The maximum of the <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> is characterized by a ~50 m2 area of strong vertical <span class="hlt">magnetic</span> gradient and low electrical resistivity, while the surroundings show weak gradient and large resistivity. Two drill holes into this localized area show about 6 m of sandy material with some more <span class="hlt">magnetic</span> layers at about 5 m depth overlying a greenish impact melt breccia with very abundant and large clasts. Recovery in the first 9 meters is very poor, but down hole <span class="hlt">magnetic</span> gradient measurement confirms the near 6 meter <span class="hlt">magnetic</span> layer. A third hole was drilled outside the local area with strong <span class="hlt">magnetic</span> gradients and shows, starting at 2 m depth a porous gray clast-rich impact melt rock that is very similar to the impact melt rock extensively cropping out in the crater. Therefore, the three drill holes confirm that the geophysical contrast at the crater center corresponds to a geological contrast and suggest a link with hydrothermal activity. The results of laboratory measurements (<span class="hlt">magnetic</span> properties in particular) made on the drill cores will also be presented. References : Osinski, G. R. et al. 2005. MPS, 40:1759-1776 ; Pohl, J. et al. 1988. Meteoritics, 23:235-238 ; Quesnel, Y. et al. 2013. EPSL, 367:116-122.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUSM.P41A..02A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUSM.P41A..02A"><span id="translatedtitle"><span class="hlt">Magnetic</span> Signatures of Impact Fractured Rocks from Sierra Madera, Texas, USA - Implications to <span class="hlt">Magnetic</span> <span class="hlt">Anomalies</span> on Mars</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Adachi, T.; Kletetschka, G.; Wasilewski, P. J.; Mikula, V.</p> <p>2007-05-01</p> <p>Mars Express Orbiter (sounding radar data) revealed that craters of ancient origin had been covered by thick sediments in northern hemisphere. Mars MOLA topography mission identified many crater on Mars surface. Thus despite the Mars dichotomy, both northern and southern hemisphere have been covered by impacts to similar density. Mars currently has no global <span class="hlt">magnetic</span> field of internal origin. In southern hemisphere, <span class="hlt">magnetic</span> field intensities due to <span class="hlt">anomalies</span> of remanent origin are much lower over the gigantic impact craters (e.g. Hellas, Prometheus, and Argyre). Low <span class="hlt">magnetic</span> field may not relate to the absence of internal dynamo but due to impacts. For example, the aerial survey over a two billion year old, largest crater on Earth, Vredefort in South Africa observed much lower <span class="hlt">magnetic</span> intensity over the crater, despite of the strongly <span class="hlt">magnetized</span> simgle domain (SD) magnetite in shocked granites. Randomized <span class="hlt">magnetic</span> vector orientations caused by impact may be the origin of the lower <span class="hlt">magnetic</span> field observed on both Vredefort and Mars. We conducted <span class="hlt">magnetic</span> analysis for a suite of Sierra Madera Impact deformed rock sites with complete shatter cone structures and multiple striated joint set (MSJS), and the initial results were intriguing. NRM vector orientations, REM ratios, and AF demagnetization curves showed contrasted <span class="hlt">magnetic</span> signatures between the sites as well as within the samples. The NRM signatures in small scale shatter cones and larger scale shatter cones indicated shock demagnetization (SDM). The peculiar signatures of the site with MSJS may be both SDM and shock <span class="hlt">magnetization</span> (SRM). We characterized the complexity and distinct <span class="hlt">magnetic</span> signatures of impact fractured rocks. The results suggest that the size of the shatter cones and structures may reflect the <span class="hlt">magnetic</span> signatures of both intensity and directions. Also, the dimensional scale of shatter cones is indicative parameters for randomization of the <span class="hlt">magnetic</span> vector orientations. Such variations may influence on overall <span class="hlt">magnetic</span> intensity observed from a distance, which relates to <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> on Mars and Moons.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1715078G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1715078G"><span id="translatedtitle">Processing of the marine <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> of the Caribbean region and the Gulf of Mexico (GOM)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Garcia, Andreina; Dyment, Jérôme; Thébault, Erwan</p> <p>2015-04-01</p> <p>Marine <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> are useful to better understand the structure and age of the seafloor and constrain its nature and formation. In this work, we applied a dedicated processing of the NGDC marine <span class="hlt">magnetic</span> measurements over the Caribbean region. The number of available surveys amounts to 516 representing 2.612.994 data points between epochs 1958 and 2012. The pre-processing was done by survey. First, data associated to velocities lesser than 5 knots were rejected. Then, the data were corrected for the main internal field using the CM4 model for epochs ranging between 1960 and 2002,5 and the IGRF-11 model outside the time range of the CM4 model. A visual inspection of the <span class="hlt">anomalies</span> allowed us to identify, to remove evident outliers and to define a priority order for each survey. We evaluated the <span class="hlt">magnetic</span> heading effect and corrected the data for it although statistics analysis suggested that this correction brings only a marginal improvement. The cross-overs differences were estimated using the x2sys package (Wessel, 2010) and then corrected using a Matlab code. The statistics confirmed the importance of this processing and improved the internal crossovers, with in particular a clear reduction of extreme values. This processing allows us to present a marine <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> map of the Caribbean region and the Gulf of Mexico to 0.18 degree spatial resolution and to discuss the <span class="hlt">magnetic</span> signature of some of the striking structures of the area.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014GeoRL..41.7997B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014GeoRL..41.7997B"><span id="translatedtitle">Contribution of multidomain titanomagnetite to the intensity and stability of Mars crustal <span class="hlt">magnetic</span> <span class="hlt">anomalies</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brachfeld, Stefanie; Cuomo, David; Tatsumi-Petrochilos, Lisa; Bowles, Julie A.; Shah, Deepa; Hammer, Julia</p> <p>2014-11-01</p> <p>Two basalts with compositions relevant to the crusts of Mars and Earth were synthesized at igneous temperatures and held at 650°C for 21 to 257 days under quartz-fayalite-magnetite fO2 buffer conditions. The run products are germane to slowly cooled igneous intrusions, which might be a significant volumetric fraction of the Martian crust and carriers of <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> in the Southern Highlands. Both basalts acquired intense thermoremanent <span class="hlt">magnetizations</span> and intense but easily demagnetized anhysteretic remanent <span class="hlt">magnetizations</span> carried by homogeneous multidomain titanomagnetite. Hypothetical intrusions on Mars composed of these materials would be capable of acquiring intense remanences sufficient to generate the observed <span class="hlt">anomalies</span>. However, the remanence would be easily demagnetized by impact events after the cessation of the Mars geodynamo. Coercivity enhancement by pressure or formation of single domain regions via exsolution within the multidomain grains is necessary for long-term retention of a remanence carried exclusively by multidomain titanomagnetite grains.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19950007853','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19950007853"><span id="translatedtitle">Towards developing an analytical procedure of defining the equatorial electrojet for correcting satellite <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> data</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ravat, Dhananjay; Hinze, William J.</p> <p>1991-01-01</p> <p>Analysis of the total <span class="hlt">magnetic</span> intensity MAGSAT data has identified and characterized the variability of ionospheric current effects as reflected in the geomagnetic field as a function of longitude, elevation, and time (daily as well as monthly variations). This analysis verifies previous observations in POGO data and provides important boundary conditions for theoretical studies of ionospheric currents. Furthermore, the observations have led to a procedure to remove these temporal perturbations from lithospheric MAGSAT <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> data based on 'along-the-dip-latitude' averages from dawn and dusk data sets grouped according to longitudes, time (months), and elevation. Using this method, high-resolution lithospheric <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> maps have been prepared of the earth over a plus or minus 50 deg latitude band. These maps have proven useful in the study of the structures, nature, and processes of the lithosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5667897','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5667897"><span id="translatedtitle">Chemical remanent <span class="hlt">magnetization</span> of oceanic crust</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Verhoef, J. ); Arkani-Hamed, J. )</p> <p>1990-10-01</p> <p>The effects of chemical remanent <span class="hlt">magnetization</span> (CRM) of oceanic crust on the anomalous skewness of sea-floor <span class="hlt">spreading</span> <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> are investigated. Considering a realistic constraint that the actual <span class="hlt">magnetization</span> at <span class="hlt">anomaly</span> M0 is reversed, the CRM of layer 2A basalts fails to explain the anomalous skewness of the <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>. The CRM of the deeper layers does contribute to the anomalous skewness of <span class="hlt">anomalies</span> 33/34, but the major contribution comes from thermal remanent <span class="hlt">magnetization</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMGP51B3720K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMGP51B3720K"><span id="translatedtitle"><span class="hlt">Magnetic</span> <span class="hlt">anomalies</span> on Io and their relationship to the spatial distribution of volcanic centers</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Knicely, J.; Everett, M. E.; Sparks, D. W.</p> <p>2014-12-01</p> <p>The analysis of terrestrial <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> has long proved useful for constraining crustal structure and dynamics. Here, we study Jupiter's moon, Io, using <span class="hlt">magnetics</span>. We conduct forward modeling to make predictions of the crustal <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> distribution on Io. Io is the most volcanic body in the solar system due to tidal heating from its Laplace resonance with Europa and Ganymede, causing extensive sulfur and silicate volcanism. We assume the <span class="hlt">magnetic</span> susceptibility, which controls the measured <span class="hlt">magnetic</span> signal, is controlled by temperature. Continuous overturn of the crust controls the vertical temperature profile, and local volcanic centers give the lateral temperature structure. As non-<span class="hlt">magnetic</span> sulfur volcanism occurs at cool temperatures beneath the Curie point, it should not greatly affect the planetary <span class="hlt">magnetism</span> and consequently is ignored in this paper. We assume that the average crustal temperatures are determined by a model of continuous burial by newly erupted material (O'Reilly and Davies 1981, Geophysical Research Letters), which put the Curie isotherm at great depth. We use a cylindrically symmetric model of the thermal evolution of the crust around an isolated volcanic center to obtain the local deviations in the thickness of the magnetizable layer. The crustal rocks are presumed to be mafic or ultramafic in composition, based on their spectral signatures, the temperature of the silicate volcanic eruptions, and their rheology as inferred from flow structures. Analysis of the 1997 Pillan eruption suggests a composition similar to lunar mare basalt or komatiite. The <span class="hlt">magnetic</span> and thermal properties of lunar mare basalt have been well studied since the Apollo missions. Unaltered terrestrial ultramafics have been studied sufficiently to constrain their properties. A common technique of discretizing the <span class="hlt">magnetized</span> material into prisms and summing the <span class="hlt">magnetic</span> field of each prism as per Blakely (1995) was used to obtain an estimate of the crustal <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> of Io as they would be measured by a satellite. The mapping is displayed as zonal bands so that a Cartesian geometry may be used. Early results indicated an accuracy better than 2 nT is required to detect the <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> generated by volcanic activity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19860028008&hterms=Curie&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DCurie','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19860028008&hterms=Curie&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DCurie"><span id="translatedtitle">The satellite <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> of Ahaggar - Evidence for African Plate motion</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Phillips, R. J.; Brown, C. R.</p> <p>1985-01-01</p> <p>The Ahaggar volcanic province of North Central Africa is considered a region of excess heat flow (hot spot) and hence elevated Curie isotherm. Using a modified version of the Parker FFT potential field representation, <span class="hlt">magnetic</span> signals were calculated at Magsat altitudes for models in which the African Plate is both fixed and moving. The moving-plate model extends the Curie isotherm <span class="hlt">anomaly</span> in the direction of plate motion and provides a satisfactory match to vertical component <span class="hlt">anomaly</span> data when the magnitude of plate velocity is 0.75 cm/yr. Although the signal levels are marginal for the scalar component <span class="hlt">anomalies</span> of this region, the same model provides an adequate match to this data set and is clearly preferable to a fixed-plate model.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EP%26S...68...56C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EP%26S...68...56C"><span id="translatedtitle"><span class="hlt">Spread</span> F occurrence and drift under the crest of the equatorial ionization <span class="hlt">anomaly</span> from continuous Doppler sounding and FORMOSAT-3/COSMIC scintillation data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chum, Jaroslav; Liu, Jann-Yenq; Chen, Shih-Ping; Cabrera, Miguel Angel; Laštovička, Jan; Baše, Jiří; Burešová, Dalia; Fišer, Jiří; Hruška, František; Ezquer, Rodolfo</p> <p>2016-04-01</p> <p>A relatively new method based on measurements by multipoint continuous Doppler sounding is applied to study the occurrence rate, propagation velocities, and directions of <span class="hlt">spread</span> F structures over Tucumán, Northern Argentina, and Taiwan, both of which were under the crest of the equatorial ionization <span class="hlt">anomaly</span> in 2014. In addition, <span class="hlt">spread</span> F is studied globally over the same time period from the S4 scintillation index measured onboard FORMOSAT-3/COSMIC (F3/C) satellite. It is shown that the continuous Doppler sounding gives results that are consistent with S4 data and with previous optical, global positioning system (GPS), and satellite measurements. Most of the <span class="hlt">spread</span> F events were observed from September to March, i.e., during the local summer half of the year in Tucumán, whereas in Taiwan, the highest occurrence rate was observed around equinoxes. The occurrence rate in Tucumán was about four times higher than that in Taiwan. The propagation velocities and directions were estimated from the Doppler shift spectrograms. The <span class="hlt">spread</span> structures related to <span class="hlt">spread</span> F propagated roughly eastward at velocities from ~70 to ~200 m s-1 during nighttime hours. The mean observed horizontal velocity was 140 m s-1 over Tucumán and 107 m s-1 over Taiwan. The local times at which the highest velocities were observed roughly correspond to local times with highest values of scintillation index S4, at ~20 to 23 LT. In addition, a comparison of measured drift velocities with neutral wind velocities predicted by models is provided. The observed velocities usually exceeded the horizontal neutral wind velocities predicted by the HWM14 model for the locations and times of observations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003EAEJA.....1663E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003EAEJA.....1663E"><span id="translatedtitle">Gravity and <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> of the Cyprus arc and tectonic implications</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ergün, M.; Okay, S.; Sari, C.; Oral, E. Z.</p> <p>2003-04-01</p> <p>In present day, eastern Mediterranean is controlled by the collision of the African and Eurasian plates and displacements of Arabian, Anatolian and Aegean micro-plates. The boundary between African and Eurasian plates is delineated by the Hellenic arc and Pliny-Strabo trench in the west and the Cyprus arc and a diffuse fault system of the Eastern Anatolian Fault zone in the east. The available gravity and <span class="hlt">magnetic</span> data from the easternmost Mediterranean allow to subdivide this basin into three provinces: the northeastern Mediterranean north of the Cyprus Arc; the Levant Basin south of the Cyprus Arc and east of the line that roughly continues the Suez rift trend toward the Gulf of Antalya, between Cyprus and Anaximander Mountains; and the Mediterranean Ridge, Herodotus Basin west of this line. High <span class="hlt">anomalies</span> observed in Cyprus and the sea region at the south is prominent in the gravity data. The Bouguer gravity <span class="hlt">anomaly</span> reaches its maximum values over Cyprus, where it is most probably caused by high dense Troodos ophiolites. The uplifted oceanic crust causes high Bouguer <span class="hlt">anomaly</span> also seen in the vicinity of Eratosthenes Seamount. Another result obtained from gravity data is that the crust under Herodotos and Rhodes basins is somehow oceanic and Anaximander, Eratosthenes and Cyprus are continental fragments. There are no linear <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> in the Mediterranean. But there are <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> over the Eratosthenes seamount and as well as from Cyprus to the Antalya basin due to the ophiolitic bodies. In Cyprus, the last compressional deformations were defined near the Miocene/Pliocene boundary. The extensional deformation associated with the Antalya basin appears to be separated by a zone of the Florence rise and Anaximander Mountains affected by differential tectonic movements. Eratosthenes Seamount is a positive crustal feature in the process of collision with Cyprus along an active margin; there is clearly a potential tectonic relationship to the onland geology of Cyprus. Eratosthenes is in the process of actively being underthrust both northwards and southwards under opposing margins.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20040081281','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20040081281"><span id="translatedtitle">Bangui <span class="hlt">Anomaly</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Taylor, Patrick T.</p> <p>2004-01-01</p> <p>Bangui <span class="hlt">anomaly</span> is the name given to one of the Earth s largest crustal <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> and the largest over the African continent. It covers two-thirds of the Central African Republic and therefore the name derives from the capitol city-Bangui that is also near the center of this feature. From surface <span class="hlt">magnetic</span> survey data Godivier and Le Donche (1962) were the first to describe this <span class="hlt">anomaly</span>. Subsequently high-altitude world <span class="hlt">magnetic</span> surveying by the U.S. Naval Oceanographic Office (Project <span class="hlt">Magnet</span>) recorded a greater than 1000 nT dipolar, peak-to-trough <span class="hlt">anomaly</span> with the major portion being negative (figure 1). Satellite observations (Cosmos 49) were first reported in 1964, these revealed a 40nT <span class="hlt">anomaly</span> at 350 km altitude. Subsequently the higher altitude (417-499km) POGO (Polar Orbiting Geomagnetic Observatory) satellite data recorded peak-to-trough <span class="hlt">anomalies</span> of 20 nT these data were added to Cosmos 49 measurements by Regan et al. (1975) for a regional satellite altitude map. In October 1979, with the launch of Magsat, a satellite designed to measure crustal <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>, a more uniform satellite altitude <span class="hlt">magnetic</span> map was obtained. These data, computed at 375 km altitude recorded a -22 nT <span class="hlt">anomaly</span> (figure 2). This elliptically shaped <span class="hlt">anomaly</span> is approximately 760 by 1000 km and is centered at 6%, 18%. The Bangui <span class="hlt">anomaly</span> is composed of three segments; there are two positive <span class="hlt">anomalies</span> lobes north and south of a large central negative field. This displays the classic pattern of a <span class="hlt">magnetic</span> anomalous body being <span class="hlt">magnetized</span> by induction in a zero inclination field. This is not surprising since the <span class="hlt">magnetic</span> equator passes near the center of this body.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhRvB..93b4502S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhRvB..93b4502S"><span id="translatedtitle"><span class="hlt">Magnetic</span> anisotropy and thermodynamic <span class="hlt">anomaly</span> in the superconducting mixed state of UBe13 probed by static dc <span class="hlt">magnetization</span> measurements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shimizu, Yusei; Haga, Yoshinori; Yanagisawa, Tatsuya; Amitsuka, Hiroshi</p> <p>2016-01-01</p> <p>Static dc <span class="hlt">magnetization</span> M (H ) measurements were performed for a single crystal of UBe13 down to 0.1 K in <span class="hlt">magnetic</span> fields up to 80 kOe for H ∥<100 > and H ∥<110 > . For both field directions, an unusual <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> was observed at HMag*˜20 -30 kOe in the superconducting mixed state. This <span class="hlt">anomaly</span> was seen in the thermal-equilibrium-<span class="hlt">magnetization</span> curves as well as the increasing- and decreasing-field processes of the raw <span class="hlt">magnetization</span> curves, implying a change of the thermodynamic property at HMag*. Furthermore, the <span class="hlt">magnetic</span> anisotropy of the superconducting diamagnetic response is found to be significant above HMag*, possibly associated with the anisotropy of the upper critical field Hc 2. Considering the suppression of reduced upper critical field h* and the dramatic decrease of Maki parameter κ2 around 0.9 Tc , the paramagnetic effect is present in UBe13. The paramagnetic effect in UBe13 could become anisotropic at low temperature below ˜Tc/2 . An alternative explanation of the <span class="hlt">magnetic</span> anisotropy is however that the anisotropy of the nonlinear susceptibility for the heavy electrons in the vortex cores becomes significant below ˜Tc/2 .</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1999JMMM..202..385C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1999JMMM..202..385C"><span id="translatedtitle"><span class="hlt">Magnetic</span> and transport eddy-current <span class="hlt">anomalies</span> in cylinders with core-and-shell regions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, D.-X.; Pascual, L.; Fraga, E.; Vazquez, M.; Hernando, A.</p> <p>1999-08-01</p> <p>For a conducting <span class="hlt">magnetic</span> cylinder of radius r0, conductivity σ, and regionally uniform DC permeabilities μ c, μ s, and μb in the core, the shell, and the core-shell border at r= rb< r0, the complex AC permeability μ and impedance Z are calculated analytically from the Maxwell equations and the Ohm law. Compared with the results of the classical models with uniform local DC permeability, the low-frequency eddy-current <span class="hlt">anomaly</span> factors and the high-frequency <span class="hlt">anomaly</span> behaviors are quantitatively and conceptually explained with respect to different <span class="hlt">magnetic</span> structures of the cylinder. The results can be used for quantitative studies of domain structures in ferromagnetic wires through AC permeability and impedance measurements and analyses.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.usgs.gov/of/2004/1202/','USGSPUBS'); return false;" href="http://pubs.usgs.gov/of/2004/1202/"><span id="translatedtitle"><span class="hlt">Magnetic</span> Properties of Quaternary Deposits, Kenai Peninsula, Alaska -- Implications for Aeromagnetic <span class="hlt">Anomalies</span> of Upper Cook Inlet</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Saltus, R.W.; Haeussler, P.J.</p> <p>2004-01-01</p> <p>We measured <span class="hlt">magnetic</span> susceptibilities of exposed Quaternary deposits on several beach cliffs and river banks on the Kenai Peninsula near Soldotna, Alaska. Data, descriptions, and photos from nine sites are included in this report. The mean susceptibility for Quaternary materials in this region is approximately 2.5 x 10-3 SI units. This is sufficiently <span class="hlt">magnetic</span> to produce subtle aeromagnetic <span class="hlt">anomalies</span> such as those observed to correlate with topographic features in the region of the measurements. The highest susceptibilities measured (greater than 20 x 10-3 SI units) may help, at least in part, to explain moderate amplitude aeromagnetic <span class="hlt">anomalies</span> observed elsewhere in Cook Inlet, particularly those relating to structures showing Quaternary movement. Comparison of measured beach cliff susceptibility and susceptibility predicted from idealized formulas and two-dimensional cliff models suggests that measured susceptibilies underestimate true bulk susceptibility by 20 percent to 50 percent in this region.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003JGRB..108.2097S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003JGRB..108.2097S"><span id="translatedtitle">Episodic dike swarms inferred from near-bottom <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> maps at the southern East Pacific Rise</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shah, Anjana K.; Cormier, Marie-Helene; Ryan, William B. F.; Jin, Wen; Sinton, John; Bergmanis, Eric; Carlut, Julie; Bradley, Al; Yoerger, Dana</p> <p>2003-02-01</p> <p>Near-bottom, high-resolution <span class="hlt">magnetic</span> field data gathered at the southern East Pacific Rise near 17°28'S, 18°14'S, and 18°37'S, using the autonomous underwater vehicle Autonomous Benthic Explorer (ABE) echo various geologic structures, including void space within lobate caverns, recent pillow mounds, and hydrothermal vent activity. This study is focused on a <span class="hlt">magnetic</span> field low extending several kilometers along axis, coincident with a trough created by the draining of a lava lake during a highly effusive fissure eruption at 17°28'S. Similar lows are observed at three other drained lava lake troughs, including one which is at least 1800 years old, residing 400 m away from the present-day axis. We attribute these lows to the presence of shallow dike swarms. The degree to which other geologic features may contribute to the lows is constrained using geologic, geophysical, and geochemical observations and forward modeling. Compositional analyses of Alvin samples at 17°28'S do not support Fe or Ti variations as a primary source. Hypotheses requiring hydrothermal alteration and porosity variations are both inconsistent with geologic observations and near-bottom gravity data analysis from similar areas. Previous mappings between paleointensity variations and the observed <span class="hlt">magnetic</span> field over distances of several kilometers from the axis suggest that such variations do not create the field low. The dominant source of the <span class="hlt">magnetization</span> low is most likely the presence of a 100-200 m wide region of shallow dikes which are poorly <span class="hlt">magnetized</span> relative to extrusives, or a region heated above <span class="hlt">magnetic</span> blocking or Curie temperatures by intrusions during the most recent eruption (though the latter interpretation cannot explain the low at the fossil trough). In the first case, this extrusive thinning implies a change in eruptive behavior over the last 750-1500 years given the local <span class="hlt">spreading</span> rate. For the latter case, thermal models suggest the <span class="hlt">anomaly</span> had to have been created by a dike swarms totaling at least 45 m width during the most recent eruption(s), corresponding to ˜300 years of plate <span class="hlt">spreading</span>. Models indicate that the source of the low is centered slightly east of the axial trough. This offset suggests that the axis has been progressively migrating westward over the past millennium, consistent with other studies covering greater length and timescales. Westward migration provides an explanation for the preferential emplacement of recent lavas flows west of the axis, evident in ABE bathymetry and submersible observations.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_10 --> <div id="page_11" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="201"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19870008824','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19870008824"><span id="translatedtitle">Remanent <span class="hlt">magnetization</span> and 3-dimensional density model of the Kentucky <span class="hlt">anomaly</span> region</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mayhew, M. A.; Estes, R. H.; Myers, D. M.</p> <p>1984-01-01</p> <p>A three-dimensional model of the Kentucky body was developed to fit surface gravity and long wavelength aeromagnetic data. <span class="hlt">Magnetization</span> and density parameters for the model are much like those of Mayhew et al (1982). The <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> due to the model at satellite altitude is shown to be much too small by itself to account for the <span class="hlt">anomaly</span> measured by Magsat. It is demonstrated that the source region for the satellite <span class="hlt">anomaly</span> is considerably more extensive than the Kentucky body sensu stricto. The extended source region is modeled first using prismatic model sources and then using dipole array sources. <span class="hlt">Magnetization</span> directions for the source region found by inversion of various combinations of scalar and vector data are found to be close to the main field direction, implying the lack of a strong remanent component. It is shown by simulation that in a case (such as this) where the geometry of the source is known, if a strong remanent component is present its direction is readily detectable, but by scalar data as readily as vector data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010cosp...38..419S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010cosp...38..419S"><span id="translatedtitle">Interaction between solar wind and lunar <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> observed by MAP-PACE on Kaguya</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Saito, Yoshifumi; Yokota, Shoichiro; Tanaka, Takaaki; Asamura, Kazushi; Nishino, Masaki N.; Yamamoto, Tadateru I.; Tsunakawa, Hideo</p> <p></p> <p>It is well known that the Moon has neither global intrinsic <span class="hlt">magnetic</span> field nor thick atmosphere. Different from the Earth's case where the intrinsic global <span class="hlt">magnetic</span> field prevents the solar wind from penetrating into the magnetosphere, solar wind directly impacts the lunar surface. <span class="hlt">MAgnetic</span> field and Plasma experiment -Plasma energy Angle and Composition Experiment (MAP-PACE) on Kaguya (SELENE) completed its 1.5-year observation of the low energy charged particles around the Moon on 10 June 2009. Kaguya was launched on 14 September 2007 by H2A launch vehicle from Tanegashima Space Center in Japan. Kaguya was inserted into a circular lunar polar orbit of 100km altitude and continued observation for nearly 1.5 years till it impacted the Moon on 10 June 2009. During the last 5 months, the orbit was lowered to 50km-altitude between January 2009 and April 2009, and some orbits had further lower perilune altitude of 10km after April 2009. MAP-PACE consisted of 4 sensors: ESA (Electron Spectrum Analyzer)-S1, ESA-S2, IMA (Ion Mass Analyzer), and IEA (Ion Energy Analyzer). Since each sensor had hemispherical field of view, two electron sensors and two ion sensors that were installed on the spacecraft panels opposite to each other could cover full 3-dimensional phase space of low energy electrons and ions. One of the ion sensors IMA was an energy mass spectrometer. IMA measured mass identified ion energy spectra that had never been obtained at 100km altitude polar orbit around the Moon. When Kaguya flew over South Pole Aitken region, where strong <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> exist, solar wind ions reflected by <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> were observed. These ions had much higher flux than the solar wind protons scattered at the lunar surface. The <span class="hlt">magnetically</span> reflected ions had nearly the same energy as the incident solar wind ions while the solar wind protons scattered at the lunar surface had slightly lower energy than the incident solar wind ions. At 100km altitude, when the reflected ions were observed, the simultaneously measured electrons were often heated and the incident solar wind ions were sometimes slightly decelerated. At 50km altitude, when the reflected ions were observed, proton scattering at the lunar surface clearly disappeared. It suggests that there exists an area on the lunar surface where solar wind does not impact. At 10km altitude, the interaction between the solar wind ions and the lunar <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> was remarkable with clear deceleration of the incident solar wind ions and heating of the reflected ions as well as significant heating of the electrons. Calculating velocity moments including density, velocity, temperature of the ions and electrons, we have found that there exists 100km scale regions over strong <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> where plasma parameters are quite different from the outside. Solar wind ions observed at 10km altitude show several different behaviors such as deceleration without heating and heating in a limited region inside the <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> that may be caused by the <span class="hlt">magnetic</span> field structure. The deceleration of the solar wind has the same ∆E/q (∆E : deceleration energy, q: charge) for different species, which constraints the possible mechanisms of the interaction between solar wind and <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015NPGeo..22..579M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NPGeo..22..579M"><span id="translatedtitle">Identification of <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> based on ground <span class="hlt">magnetic</span> data analysis using multifractal modelling: a case study in Qoja-Kandi, East Azerbaijan Province, Iran</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mansouri, E.; Feizi, F.; Karbalaei Ramezanali, A. A.</p> <p>2015-10-01</p> <p>Ground <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> separation using the reduction-to-the-pole (RTP) technique and the fractal concentration-area (C-A) method has been applied to the Qoja-Kandi prospecting area in northwestern Iran. The geophysical survey resulting in the ground <span class="hlt">magnetic</span> data was conducted for <span class="hlt">magnetic</span> element exploration. Firstly, the RTP technique was applied to recognize underground <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>. RTP <span class="hlt">anomalies</span> were classified into different populations based on the current method. For this reason, drilling point area determination by the RTP technique was complicated for <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>, which are in the center and north of the studied area. Next, the C-A method was applied to the RTP <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> (RTP-MA) to demonstrate <span class="hlt">magnetic</span> susceptibility concentrations. This identification was appropriate for increasing the resolution of the drilling point area determination and decreasing the drilling risk issue, due to the economic costs of underground prospecting. In this study, the results of C-A modelling on the RTP-MA are compared with 8 borehole data. The results show that there is a good correlation between <span class="hlt">anomalies</span> derived via the C-A method and the log report of boreholes. Two boreholes were drilled in <span class="hlt">magnetic</span> susceptibility concentrations, based on multifractal modelling data analyses, between 63 533.1 and 66 296 nT. Drilling results showed appropriate magnetite thickness with grades greater than 20 % Fe. The total associated with <span class="hlt">anomalies</span> containing andesite units hosts iron mineralization.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26762781','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26762781"><span id="translatedtitle">Effects of edge <span class="hlt">magnetism</span> on the Kohn <span class="hlt">anomalies</span> of zigzag graphene nanoribbons.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Culchac, F J; Capaz, Rodrigo B</p> <p>2016-02-12</p> <p>The effects of edge <span class="hlt">magnetism</span> on the Kohn <span class="hlt">anomaly</span> (KA) of the G-band phonons of zigzag graphene nanoribbons (ZGNRs) are studied using a combination of the tight-binding and mean-field Hubbard models. We show that the opening of an energy gap, induced by <span class="hlt">magnetic</span> ordering, significantly changes the KA effects, particularly for narrow ribbons in which the gap is larger than the phonon energy. Therefore, the G-band phonon frequency and lifetime are altered for a <span class="hlt">magnetically</span>-ordered edge state with respect to an unpolarized edge state. The effects of temperature, ZGNR width, doping and transverse electric fields are systematically investigated. We propose using this effect to probe the <span class="hlt">magnetic</span> order of edge states in graphene nanoribbons using Raman spectroscopy. PMID:26762781</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016Nanot..27f5707C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016Nanot..27f5707C"><span id="translatedtitle">Effects of edge <span class="hlt">magnetism</span> on the Kohn <span class="hlt">anomalies</span> of zigzag graphene nanoribbons</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Culchac, F. J.; Capaz, Rodrigo B.</p> <p>2016-02-01</p> <p>The effects of edge <span class="hlt">magnetism</span> on the Kohn <span class="hlt">anomaly</span> (KA) of the G-band phonons of zigzag graphene nanoribbons (ZGNRs) are studied using a combination of the tight-binding and mean-field Hubbard models. We show that the opening of an energy gap, induced by <span class="hlt">magnetic</span> ordering, significantly changes the KA effects, particularly for narrow ribbons in which the gap is larger than the phonon energy. Therefore, the G-band phonon frequency and lifetime are altered for a <span class="hlt">magnetically</span>-ordered edge state with respect to an unpolarized edge state. The effects of temperature, ZGNR width, doping and transverse electric fields are systematically investigated. We propose using this effect to probe the <span class="hlt">magnetic</span> order of edge states in graphene nanoribbons using Raman spectroscopy.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70036196','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70036196"><span id="translatedtitle">Chapter 3: Circum-Arctic mapping project: New <span class="hlt">magnetic</span> and gravity <span class="hlt">anomaly</span> maps of the Arctic</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Gaina, C.; Werner, S.C.; Saltus, R.; Maus, S.; Aaro, S.; Damaske, D.; Forsberg, R.; Glebovsky, V.; Johnson, K.; Jonberger, J.; Koren, T.; Korhonen, J.; Litvinova, T.; Oakey, G.; Olesen, O.; Petrov, O.; Pilkington, M.; Rasmussen, T.; Schreckenberger, B.; Smelror, M.</p> <p>2011-01-01</p> <p>New Circum-Arctic maps of <span class="hlt">magnetic</span> and gravity <span class="hlt">anomalies</span> have been produced by merging regional gridded data. Satellite <span class="hlt">magnetic</span> and gravity data were used for quality control of the long wavelengths of the new compilations. The new Circum-Arctic digital compilations of <span class="hlt">magnetic</span>, gravity and some of their derivatives have been analyzed together with other freely available regional and global data and models in order to provide a consistent view of the tectonically complex Arctic basins and surrounding continents. Sharp, linear contrasts between deeply buried basement blocks with different <span class="hlt">magnetic</span> properties and densities that can be identified on these maps can be used, together with other geological and geophysical information, to refine the tectonic boundaries of the Arctic domain. ?? 2011 The Geological Society of London.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19800022475','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19800022475"><span id="translatedtitle">Spherical Earth analysis and modeling of lithospheric gravity and <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>. Ph.D. Thesis - Purdue Univ.</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Vonfrese, R. R. B.; Hinze, W. J.; Braile, L. W.</p> <p>1980-01-01</p> <p>A comprehensive approach to the lithospheric analysis of potential field <span class="hlt">anomalies</span> in the spherical domain is provided. It has widespread application in the analysis and design of satellite gravity and <span class="hlt">magnetic</span> surveys for geological investigation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/21554476','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/21554476"><span id="translatedtitle">Contrast-enhanced portal <span class="hlt">magnetic</span> resonance angiography in dogs with suspected congenital portal vascular <span class="hlt">anomalies</span>.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mai, Wilfried; Weisse, Chick</p> <p>2011-01-01</p> <p>Contrast-enhanced multiphase <span class="hlt">magnetic</span> resonance angiography (CE-MRA) was used in 17 dogs with a suspected congenital portal vascular <span class="hlt">anomaly</span>. Portal vascular <span class="hlt">anomalies</span> were identified in 16 of the 17 dogs. Eleven had a single intrahepatic portocaval shunt (two central divisional, three right divisional, and six left divisional), one dog had a double intrahepatic portocaval shunt, one dog had a hepatic arteriovenous malformation, one dog had a complex intrahepatic porto-caval shunt. Two dogs had an extrahepatic portosystemic shunt and no shunt was identified in one dog. Total imaging time was <10 min and image quality was good to excellent in all dogs. Portal CE-MRA is a feasible, fast and non invasive technique to diagnose portal vascular <span class="hlt">anomalies</span> in dogs, with a large field-of-view and good anatomic depiction of the abnormal vessels. Based on these results, CE-MRA is an efficient imaging technique for the diagnosis of portal vascular <span class="hlt">anomalies</span> in dogs. PMID:21554476</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/22253123','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/22253123"><span id="translatedtitle">[What is the impact of fetal <span class="hlt">magnetic</span> resonance imaging (MRI) on prenatal diagnosis of cerebral <span class="hlt">anomalies</span>.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>de Laveaucoupet, Jocelyne; Bekiesińska-Figatowska, Monika; Rutkowska, Magdalena</p> <p>2011-01-01</p> <p>Fetal <span class="hlt">magnetic</span> resonance imaging (MRI) is an adjunct to sonography (US), often necessary when cerebral abnormality is suspected. With use of fast sequences, such as T2 HASTE or SSFSE, gradient-echo T1- weighted images and diffusion-weighted imaging, it is possible to obtain images of fetal brain in three planes without mother's sedation. Diagnosing brain <span class="hlt">anomalies</span> using MRI requires good knowledge of normal anatomy depending on gestational age: phases of neuronal migration, sulcation and gyration, myelination in particular. The main indications to perform MRI are as follows : ventricular dilatation, midline and posterior fossa abnormalities, microcephaly (in search for migrational disorders), cerebral location of tuberous sclerosis which is suspected when cardiac tumours are detected. MRI allows to confirm US diagnosis and to answer the question whether the abnormality is isolated or complex. This enables not only to establish the diagnosis but also the prognosis. This method plays an important role in the work of the interdisciplinary team managing the pregnancies with a suspicion of congenital <span class="hlt">anomalies</span>. Prenatal MRI is a great progress in diagnosing brain <span class="hlt">anomalies</span> and has become indispensable in modern perinatology in the last decades. The situation of mother and child after the <span class="hlt">anomaly</span> had been detected requires discussion and care of the interdisciplinary team consisting of an obstetrician, neonatologist, radiologist, geneticist, pathologist, psychologist and paediatric neurologist. PMID:22253123</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009EGUGA..1112604O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009EGUGA..1112604O"><span id="translatedtitle">Interpretation of regional <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> of the East - European Platform for spherical Earth</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Orliuk, M.; Marchenko, A.</p> <p>2009-04-01</p> <p>Regional <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> (RMA) are one of important information generators for research of deep structure of the Earth's crust and small scale forecasting of mineral deposits. RMA were selected and interpreted first in the 2D variant by Krutikhovskaya Z.A. with co-authors for the Ukrainian Shield (Krutikhovskaya at al., 1982). In future RMA it was selected for territory of Ukraine and East - European platform (EEP) (Pashkevich I.K. et al., 1990; Orlyuk M.I., 1999), and their interpretation is executed in a 3D variant (Orlyuk M.I., 1999; Orlyuk M.I., 2000). First approaching location of sources RMA and values of the <span class="hlt">magnetic</span> susceptibility it was got as a result working out of small scale 3D <span class="hlt">magnetic</span> models of Ukrainian Shield, territory of Ukraine and East - European platform. Thus interpretation was executed at the identical values of the <span class="hlt">magnetic</span> field of Earth for large territories. An account of spherical of Earth is the new stage of interpretation of RMA. The sizes of <span class="hlt">anomalies</span> (tens kilometers in a crossing and hundreds kilometers by a slowness) require the account of spherical. All of it needed development adequate Ba of the mathematical, algorithmic and programmatic providing of interpretation of RMA. The mathematical providing and programmatic algorithmic complex was developed by V.M.Kovalenko-Zavoysky and I.M.Ivashchenko (2006), which allows to calculate the vector of <span class="hlt">magnetized</span> sources of RMA for arbitrary correlation of the constituents vector Ba. Presence of values of the module induction of the geomagnetic field B, component of the normal <span class="hlt">magnetic</span> field of Earth B0, B0x, B0y, B0z on the epoch of calculation of <span class="hlt">anomaly</span> Ba and it Bax, Bay, Baz- component is need for calculations. Quantitative interpretation of RMA takes into account nonlinear character of the field Ba. Early during interpretation of <span class="hlt">anomaly</span> of Ba "substituted" the <span class="hlt">anomalies</span> of vertical component of Baz, that led to the substantial errors during interpretation. The specific of the interpretation of RMA in spherical coordinates are used geocentric and local systems coordinates. The results of calculation are given in the geocentric system of coordinates (latitude and longitude point of the field calculation - in degrees and minutes). This interpretation complex was used for interpretation of the RMA of the East-European platform. Interpretation was taken to the calculation and interpolation component of the normal geomagnetic field on a spherical surface and decision of direct task in spherical coordinates. A spatial location and intensity of <span class="hlt">anomalies</span> is taken from digital map of the regional <span class="hlt">magnetic</span> field Ba.reg of the East - European platform and surrounding territories (Orlyuk, 2000). The models of sources RMA were set a few spherical blocks, each of which was characterized homogeneous <span class="hlt">magnetic</span> susceptibility and different values of the normal geomagnetic field. According to calculations <span class="hlt">magnetic</span> susceptibility of sources of north part of EEP changes from ? =0,002 Si to ? = 0, 0058 Si (at the value of the normal geomagnetic field B0 =52 500- 54 500 nT), and from ?=0,001 Si to ?= 0,006 Si for south part of EEP (at B0 =49 500- of 52 500 nT). So, the methodical features interpretation of the geomagnetic field are considered taking into account spherical of Earth. The first variant of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70036679','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70036679"><span id="translatedtitle">EMAG2: A 2-arc min resolution Earth <span class="hlt">Magnetic</span> <span class="hlt">Anomaly</span> Grid compiled from satellite, airborne, and marine <span class="hlt">magnetic</span> measurements</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Maus, S.; Barckhausen, U.; Berkenbosch, H.; Bournas, N.; Brozena, J.; Childers, V.; Dostaler, F.; Fairhead, J.D.; Finn, C.; von Frese, R.R.B; Gaina, C.; Golynsky, S.; Kucks, R.; Lu, Hai; Milligan, P.; Mogren, S.; Muller, R.D.; Olesen, O.; Pilkington, M.; Saltus, R.; Schreckenberger, B.; Thebault, E.; Tontini, F.C.</p> <p>2009-01-01</p> <p>A global Earth <span class="hlt">Magnetic</span> <span class="hlt">Anomaly</span> Grid (EMAG2) has been compiled from satellite, ship, and airborne <span class="hlt">magnetic</span> measurements. EMAG2 is a significant update of our previous candidate grid for the World Digital <span class="hlt">Magnetic</span> <span class="hlt">Anomaly</span> Map. The resolution has been improved from 3 arc min to 2 arc min, and the altitude has been reduced from 5 km to 4 km above the geoid. Additional grid and track line data have been included, both over land and the oceans. Wherever available, the original shipborne and airborne data were used instead of precompiled oceanic <span class="hlt">magnetic</span> grids. Interpolation between sparse track lines in the oceans was improved by directional gridding and extrapolation, based on an oceanic crustal age model. The longest wavelengths (>330 km) were replaced with the latest CHAMP satellite <span class="hlt">magnetic</span> field model MF6. EMAG2 is available at http://geomag.org/models/EMAG2 and for permanent archive at http://earthref.org/ cgi-bin/er.cgi?s=erda.cgi?n=970. ?? 2009 by the American Geophysical Union.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005AGUFMGP23A0028H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005AGUFMGP23A0028H"><span id="translatedtitle"><span class="hlt">Magnetic</span> Properties and Absolute Paleointensity of Upper Oceanic Crust Generated by Superfast Seafloor <span class="hlt">Spreading</span>, ODP Leg 209.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Herrero-Bervera, E.; Acton, G.</p> <p>2005-12-01</p> <p>We investigate the <span class="hlt">magnetic</span> mineralogy and absolute paleointensity of oceanic basalt samples from Hole 1256D, cored during Ocean Drilling Program (ODP) Leg 206. Hole 1256D is located on the Cocos Plate about 5 km east of the transition zone between marine <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> 5Bn.2n and 5Br (~15 Ma). During Leg 206, the hole penetrated 502 m into basalts of the upper oceanic crust that was generated by superfast seafloor <span class="hlt">spreading</span> (>200 mm/yr) along the East Pacific Rise. Rock <span class="hlt">magnetic</span> investigations included continuous low field (k-T) thermomagnetic analyses, alternating field (AF) and thermal demagnetization, optical microscopy, saturation isothermal remanent <span class="hlt">magnetization</span> (SIRM), and <span class="hlt">magnetic</span> grain size analyses. Following the removal of a drilling overprint, AF and thermal demagnetization paths for most samples decay linearly to the origin on orthogonal vector end point diagrams, suggesting that a stable characteristic remanent <span class="hlt">magnetization</span> component can be resolved. Optical microscopy and k-T (Curie points) identified titanomagnetites and titanomaghemites as the main <span class="hlt">magnetic</span> carriers and grain size studies indicate that the carriers are either single domain (SD) and/or pseudosingle domain (PSD) in nature. Using the modified Thellier-Coe double heating method, we determined absolute paleointensity determinations for 51 specimens sampled from different ``stratigraphic'' levels of the core. pTRM checks were performed systematically one temperature step down the last pTRM acquisition in order to document magnetomineralogical changes during heating. The temperature was incremented by steps of 50°C between room temperature and 500°C and every 25-30°C for higher temperatures. The paleointensity determinations were obtained from the slope of the Arai diagrams. Special care was taken to interpret the Arai diagrams within the same range of temperatures lower than 300°C unless a clear and unique slope was present over a higher range of temperatures. Only about 10 percent of the samples yielded acceptable results. The paleofield estimated from these samples ranges between 28 to 16 micro Teslas (i.e., VADM of 6 to 4 x 1022 A/m2), which is concordant with the average paleofield intensity for the period between 0-160 Myr (4 ± 2 x1022 A/m2) and half of the strength of the present field (~8x1022 A/m2).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000Tectp.321...57S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000Tectp.321...57S"><span id="translatedtitle">Correlation between the Palaeozoic structures from West Iberian and Grand Banks margins using inversion of <span class="hlt">magnetic</span> <span class="hlt">anomalies</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Silva, Elsa A.; Miranda, J. M.; Luis, J. F.; Galdeano, A.</p> <p>2000-05-01</p> <p>The Ibero-Armorican Arc (IAA) is a huge geological structure of Pre-Cambrian origin, tightened during hercynian times and deeply affected by the opening of the Atlantic Ocean and the Bay of Biscay. Its remnants now lie in Iberia, north-western France and the Canadian Grand Banks margins. The qualitative correlation between these three blocks has been attempted by several authors (e.g. Lefort, J.P., 1980. Un 'Fit' structural de l'Atlantique Nord: arguments geologiques pour correler les marqueurs geophysiques reconnus sur les deux marges. Mar. Geol. 37, 355-369; Lefort, J.P., 1983. A new geophysical criterion to correlate the Acadian and Hercynian orogenies of Western Europe and Eastern America. Mem. Geol. Soc. Am. 158, 3-18; Galdeano, A., Miranda, J.M., Matte, P., Mouge, P., Rossignol, C., 1990. Aeromagnetic data: A tool for studying the Variscan arc of Western Europe and its correlation with transatlantic structures. Tectonophysics 177, 293-305) using <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>, mainly because they seem to preserve the hercynian zonation, in spite of the strong thermal and mechanical processes that took place during rifting and ocean <span class="hlt">spreading</span>. In this paper, we present a new contribution to the study of the IAA structure based on the processing of a compilation of <span class="hlt">magnetic</span> data from Iberia and Grand Banks margins. To interpret the <span class="hlt">magnetic</span> signature, a Fourier-domain-based inversion technique was applied, considering a layer with a constant thickness of 10 km, and taking into account only the induced field. The digital terrain model was derived from ETOPO5 (ETOPO5, 1986. Relief map of the earth's surface. EOS 67, 121) and TerrainBase (TerrainBase, 1995. In: Row III, L.W., Hastings, D.A., Dunbar, P.K. (Eds.), Worldwide Digital Terrain Data, Documentation Manual, CD-ROM Release 1.0. GEODAS-NGDC Key to Geophysical Records. Documentation N. 30, April) databases. The pseudo-susceptibility distribution obtained was repositioned for the 156.5 Ma epoch, using the Srivastava and Verhoef [Srivastava, S.P., Verhoef, J., 1992. Evolution of Mesozoic sedimentary basins around the North Central Atlantic: a preliminary plate kinematic solution. In: Parnell, J. (Ed.), Basins on the Atlantic Seaboard: Petroleum Geology Sedimentology and Basin Evolution, Geological Society Special Publication No. 62, pp. 397-420] pole. Using this coherent <span class="hlt">magnetic</span> framework, we can verify that the continuity between adjacent blocks is quite good, in terms of the amplitude, wavenumber and <span class="hlt">magnetic</span> susceptibility pattern. If we accept that the <span class="hlt">magnetic</span> properties can be taken as a marker of the hercynian zonation, as was verified in previous studies (Miranda, J.M., Galdeano, A., Rossignol, J.C., Mendes-Victor, L.A., 1989. Aeromagnetic <span class="hlt">anomalies</span> in mainland Portugal and their tectonic implications. Earth Planet. Sci. Lett. 95, 161-177; Galdeano, A., Miranda, J.M., Matte, P., Mouge, P., Rossignol, C., 1990. Aeromagnetic data: A tool for studying the Variscan arc of Western Europe and its correlation with transatlantic structures. Tectonophysics 177, 293-305; Socias, I., 1994. Estudios de los Elementos del Campo Magnético en la España Peninsular a partir de Datos Aeromagmanéticos. Ph.D. thesis, University of Madrid), we can conclude that (1) the characteristic <span class="hlt">magnetic</span> signature of Ossa Morena Zone is absent on the Iberian Margin and west of it; (2) no eastward continuation of the Collector <span class="hlt">Anomaly</span> is found in Iberia; (3) only the inner zones of the Variscan Belt can be followed towards NW France; (4) there is a major (left lateral ?) strike-slip fault along the northern Portuguese shoreline that cuts the IAA and significantly displaces the once-contiguous variscan units.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20150010745&hterms=solar+wind&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dsolar%2Bwind','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20150010745&hterms=solar+wind&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dsolar%2Bwind"><span id="translatedtitle">Anisotropic Solar Wind Sputtering of the Lunar Surface Induced by Crustal <span class="hlt">Magnetic</span> <span class="hlt">Anomalies</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Poppe, A. R.; Sarantos, M.; Halekas, J. S.; Delory, G. T.; Saito, Y.; Nishino, M.</p> <p>2014-01-01</p> <p>The lunar exosphere is generated by several processes each of which generates neutral distributions with different spatial and temporal variability. Solar wind sputtering of the lunar surface is a major process for many regolith-derived species and typically generates neutral distributions with a cosine dependence on solar zenith angle. Complicating this picture are remanent crustal <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> on the lunar surface, which decelerate and partially reflect the solar wind before it strikes the surface. We use Kaguya maps of solar wind reflection efficiencies, Lunar Prospector maps of crustal field strengths, and published neutral sputtering yields to calculate anisotropic solar wind sputtering maps. We feed these maps to a Monte Carlo neutral exospheric model to explore three-dimensional exospheric anisotropies and find that significant anisotropies should be present in the neutral exosphere depending on selenographic location and solar wind conditions. Better understanding of solar wind/crustal <span class="hlt">anomaly</span> interactions could potentially improve our results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19730056572&hterms=ps&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dps','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19730056572&hterms=ps&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dps"><span id="translatedtitle">The detection of 'intermediate' size <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> in Cosmos 49 and OGO 2, 4, 6 data.</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Regan, R. D.; Davis, W. M.; Cain, J. C.</p> <p>1973-01-01</p> <p>Benkova, Dolginov and Simonenko have recently reported the presence of intermediate size <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> from Cosmos 49 data and hypothesized a crustal and/or upper mantle origin for these. We have examined the spherical harmonic models of the internal potential function, based on the OGO 2, 4 and 6 data and verified the locations and amplitudes of those <span class="hlt">anomalies</span> with wavelengths of approximately 4000 km. The patterns of delta-F so computed were then compared with the IZMIRAN maps and also were analyzed statistically, in both the spatial and frequency domains, using residuals computed from the raw Cosmos 49 data. The two sets of data were thus derived from completely independent sets of observations and field references. The two patterns are shown to agree very well over the whole earth surface up to the 50 deg latitude limit of Cosmos 49.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70015493','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70015493"><span id="translatedtitle">An attempt to obtain a detailed declination chart from the United States <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> map</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Alldredge, L.R.</p> <p>1989-01-01</p> <p>Modern declination charts of the United States show almost no details. It was hoped that declination details could be derived from the information contained in the existing <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> map of the United States. This could be realized only if all of the survey data were corrected to a common epoch, at which time a main-field vector model was known, before the <span class="hlt">anomaly</span> values were computed. Because this was not done, accurate declination values cannot be determined. In spite of this conclusion, declination values were computed using a common main-field model for the entire United States to see how well they compared with observed values. The computed detailed declination values were found to compare less favourably with observed values of declination than declination values computed from the IGRF 1985 model itself. -from Author</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20000080271&hterms=RAE&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DRAE','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20000080271&hterms=RAE&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DRAE"><span id="translatedtitle">Kursk <span class="hlt">Magnetic</span> <span class="hlt">Anomaly</span> at Satellite Altitude: Revisited with the Orsted Satellite</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Taylor, Patrick T.; VonFrese, Ralph R. B.; Kim, Hyung Rae</p> <p>2000-01-01</p> <p>The Kursk <span class="hlt">Magnetic</span> <span class="hlt">Anomaly</span> (KMA) of Russia (51 deg north, 37 deg east) has long been recognized as one of the largest <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> on Earth. It is associated with the massive iron-ore formations of this region, however, model studies have revealed that the relationship between the two is not obvious. In an early effort to demonstrate the validity of Magsat data for crustal research a detailed study of the KMA, at an average altitude of 350 km and the surrounding region was made. They recorded a 27 nT high and a -9 nT low giving a 37 nT peak-to-trough <span class="hlt">anomaly</span> over the immediate area of the KMA. Despite the much higher altitude of Orsted (620 to 850 km) we revisited the KMA to determine if this mission would also be able to record an associated anomalous crustal signature. The Orsted profiles we selected were from April to August 1999. From these data we chose those with an altitude range of 644 to 700 km and they were subsequently gridded, by least-squares collocation, to a mean elevation of 660 km. Both ascending and descending data were examined and signals common to both were extracted and averaged. A correlation coefficient between these two orbit orientations of 0.82 was computed. The quadrant-swapping method of Kim et al. was applied. Removal of the main geomagnetic field was accomplished with a polynomial fitting procedure. A positive <span class="hlt">anomaly</span> of >2.5 nT with ari associated negative of <-0.5 nT for a >3 nT peak-to-trough range were computed. These Magsat and Orsted results are consistent with the decay of a dipole field over the studied altitude range. Significant differences between these two <span class="hlt">anomaly</span> fields are due to the greater number of orbit profiles and therefore greater number of intersecting orbits (ascending and descending) available in the Orsted compilation. Of the four largest amplitude <span class="hlt">anomalies</span> in the Orsted field three are present in the Magsat map. The fourth (>2.5 nT), however, is associated with the Belorussian-Lithuanian anteclise. This sugaests that additional geologic information may be apparent in the new Orsted field.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFMGP34A..05S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFMGP34A..05S"><span id="translatedtitle">Analysis of vector <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> over the Bayonnaise Knoll caldera obtained from a deep-sea <span class="hlt">magnetic</span> exploration by AUV</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sayanagi, K.; Isezaki, N.; Matsuo, J.; Harada, M.; Kasaya, T.</p> <p>2011-12-01</p> <p>Geophysical surveys near the seafloor are very effective methods in order to investigate fine structures of the oceanic crust. Such surveys have increased in researches and developments of the seafloor, and will be more and more necessary in the future. For example, seabed resources like hydrothermal deposits have recently focused attention behind the international situation for natural resources like a competition of resources development. In order to estimate accurate abundance of those resources, the above detailed investigations should be needed because of low resolution of geophysical surveys on the sea and low efficiency of exploratory drilling. From such a viewpoint, we have been developing a measurement system for <span class="hlt">magnetic</span> explorations using an AUV and a deep-tow system. The <span class="hlt">magnetic</span> exploration system consists of two 3-axis flux-gate magnetometers, one/two Overhauser magnetometer(s), an optical fiber gyro, a main unit (control, communication, recording), and an onboard unit. These devices except for the onboard unit are installed in pressure cases (depth limit: 6000m). Thus this system can measure three components and total intensity of the geomagnetic field in the deep sea. In 2009, the first test of the <span class="hlt">magnetic</span> exploration system was carried out in the Kumano Basin using AUV Urashima and towing vehicle Yokosuka Deep-Tow during the R/V Yokosuka YK09-09 cruise. In this test, we sank a small <span class="hlt">magnetic</span> target to the seafloor, and examined how the system worked. As a result, we successfully detected <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> of the target to confirm the expected performance of that in the sea. In 2010, the <span class="hlt">magnetic</span> exploration system was further tested in the Bayonnaise Knoll area both using a titanium towing frame during the R/V Bosei-maru cruise and using AUV Urashima during the R/V Yokosuka YK10-17 cruise. The purpose of these tests was to evaluate the performance of the system in an actual hydrothermal deposit area for practical applications of that. The Bayonnaise Knoll is a submarine caldera with an outer rim of 2.5-3 km and a floor of 840-920 m, which is located in the Izu-Ogasawara arc. A large hydrothermal deposit, Hakurei deposit, lies in the southeast part of the caldera. In the R/V Bosei-maru cruise, we observed three components of <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> at depths of 400-570 m along SE-NW and WE tracks across the caldera. In the R/V Yokosuka YK10-17 cruise, we observed three components and total intensity of <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> at altitudes of 60-100 m around the Hakurei deposit and at depth of 500 m above the caldera. The analysis of these data is now energetically pushed forward. A 3D gridded data set of the vector <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> in the latter cruise was made by solving the Laplace's equation in the areas where observation data were not available, which is the unique procedure for analysis of the vector <span class="hlt">anomalies</span>. Several <span class="hlt">magnetization</span> solutions have been so far obtained by successive approximation and inversion methods. We will here present the measurement of the geomagnetic field and analysis of <span class="hlt">magnetization</span> structure in Bayonnaise Knoll caldera. Note that this study has been supported by the Ministry of Education, Culture, Sports, Science & Technology (MEXT).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19810031178&hterms=bts&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dbts','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19810031178&hterms=bts&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dbts"><span id="translatedtitle">An equivalent source model of the satellite-altitude <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> field over Australia</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mayhew, M. A.; Johnson, B. D.; Langel, R. A.</p> <p>1980-01-01</p> <p>The low-amplitude, long-wavelength <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> field measured between 400 and 700 km elevation over Australia by the POGO satellites is modeled by means of the equivalent source technique. <span class="hlt">Magnetic</span> dipole moments are computed for a latitude-longitude array of dipole sources on the earth's surface such that the dipoles collectively give rise to a field which makes a least squares best fit to that observed. The distribution of <span class="hlt">magnetic</span> moments is converted to a model of apparent <span class="hlt">magnetization</span> contrast in a layer of constant (40 km) thickness, which contains information equivalent to the lateral variation in the vertical integral of <span class="hlt">magnetization</span> down to the Curie isotherm and can be transformed to a model of variable thickness <span class="hlt">magnetization</span>. It is noted that the closest equivalent source spacing giving a stable solution is about 2.5 deg, corresponding to about half the mean data elevation, and that the <span class="hlt">magnetization</span> distribution correlates well with some of the principle tectonic elements of Australia.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19800025325','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19800025325"><span id="translatedtitle">Investigations of medium wavelength <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> in the eastern Pacific using Magsat data</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Harrison, C. G. A. (Principal Investigator)</p> <p>1980-01-01</p> <p>The author has identified the following significant results. Three long total <span class="hlt">magnetic</span> field profiles taken over ocean basins were analyzed. It is found that there is a significant signal in the wavelength range of 1500 to 150 km. This is too short a wavelength to be caused by the core field, which becomes insignificant at about a wavelength of 1500 km; this intermediate wavelength signal is not caused by a typical sea floor <span class="hlt">spreading</span> process, which should give maximum power in the wavelength region about 50 km. It is shown that the external <span class="hlt">magnetic</span> field contributes very little to this intermediate wavelength signal. Efforts to explain the cause of this signal have failed.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_11 --> <div id="page_12" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="221"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015M%26PS...50.1703B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015M%26PS...50.1703B"><span id="translatedtitle">Influence of redox conditions on the intensity of Mars crustal <span class="hlt">magnetic</span> <span class="hlt">anomalies</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brachfeld, Stefanie; Shah, Deepa; First, Emily; Hammer, Julia; Bowles, Julie</p> <p>2015-10-01</p> <p>We evaluate the relationship between the intensity of remanent <span class="hlt">magnetization</span> and fO2 in natural and synthetic Mars meteorites. The olivine-phyric shergottite meteorite Yamato 980459 (Y-980459) and a sulfur-free synthetic analog (Y-98*) of identical major element composition were analyzed to explore the rock <span class="hlt">magnetic</span> and remanence properties of a basalt crystallized from a primitive melt, and to explore the role of magmatic and alteration environment fO2 on Mars crustal <span class="hlt">anomalies</span>. The reducing conditions under which Y-980459 is estimated to have formed (QFM-2.5; Shearer et al. 2006) were replicated during the synthesis of Y-98*. Y-980459 contains pyrrhotite and chromite. Chromite is the only <span class="hlt">magnetic</span> phase in Y-98*. The remanence-carrying capacity of Y-980459 is comparable to other shergottites that formed in the fO2 range of QFM-3 to QFM-1. The remanence-carrying capacity of these low fO2 basalts is 1-2 orders of magnitude too weak to account for the intense crustal <span class="hlt">anomalies</span> observed in Mars's southern cratered highlands. Moderately oxidizing conditions of >QFM-1, which are more commonly observed in nakhlites and Noachian breccias, are key to generating either a primary igneous assemblage or secondary alteration assemblage capable of acquiring an intense remanent <span class="hlt">magnetization</span>, regardless of the basalt character or thermal history. This suggests that if igneous rocks are responsible for the intensely <span class="hlt">magnetized</span> crust, these oxidizing conditions must have existed in the magmatic plumbing systems of early Mars or must have existed in the crust during secondary processes that led to acquisition of a chemical remanent <span class="hlt">magnetization</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013Tectp.585...68G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013Tectp.585...68G"><span id="translatedtitle"><span class="hlt">Magnetic</span> <span class="hlt">anomalies</span> in Bahia Esperanza: A window of magmatic arc intrusions and glacier erosion over the northeastern Antarctic Peninsula</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Galindo-Zaldívar, Jesús; Ruiz-Constán, Ana; Pedrera, Antonio; Ghidella, Marta; Montes, Manuel; Nozal, Francisco; Rodríguez-Fernandez, Luis Roberto</p> <p>2013-02-01</p> <p>Bahia Esperanza, constituting the NE tip of the Antarctic Peninsula, is made up of Paleozoic clastic sedimentary rocks overlain by a Jurassic volcano-sedimentary series and intruded by Cretaceous gabbros and diorites. The area is located along the southern part of the Pacific Margin <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> belt. Field <span class="hlt">magnetic</span> researches during February 2010 contribute to determining the deep geometry of the intermediate and basic intrusive rocks. Moreover, the new field data help constrain the regional Pacific Margin <span class="hlt">Anomaly</span>, characterized up to now only by aeromagnetic and marine data. Field <span class="hlt">magnetic</span> susceptibility measurements of intrusive intermediate and basic rocks, responsible for <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>, ranges from 0.5 × 10- 3 SI in diorites to values between 0.75 × 10- 3 SI and 1.3 × 10- 3 SI in gabbros. In addition, a significant remanent <span class="hlt">magnetism</span> should also have contributed to the <span class="hlt">anomalies</span>. The regional <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> is characterized by a westward increase from 100 nT up to 750 nT, associated with large intrusive diorite bodies. They probably underlie most of the western slopes of Mount Flora. Gabbros in the Nobby Nunatak determine local residual rough <span class="hlt">anomalies</span> that extend northwards and westwards, pointing to the irregular geometry of the top of the basic rocks bodies below the Pirámide Peak Glacier. However, the southern and eastern boundaries with the Buenos Aires Glacier are sharp related to deep glacier incision. As a result of the glacier dynamics, <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> are also detected north of the Nobby Nunatak due to the extension of the anomalous body and the presence of gabbro blocks in the moraines. The Bahia Esperanza region is a key area where onshore field geological and <span class="hlt">magnetic</span> research allows us to constrain the shape of the crustal igneous intrusions and the basement glacier geometry, providing accurate data that complete regional aeromagnetic research.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015NPGD....2.1137M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NPGD....2.1137M"><span id="translatedtitle">Identification of <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> based on ground <span class="hlt">magnetic</span> data analysis using multifractal modeling: a case study in Qoja-Kandi, East Azerbaijan Province, Iran</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mansouri, E.; Feizi, F.; Karbalaei Ramezanali, A. A.</p> <p>2015-07-01</p> <p>Ground <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> separation using reduction-to-the-pole (RTP) technique and the fractal concentration-area (C-A) method has been applied to the Qoja-Kandi prosepecting area in NW Iran. The geophysical survey that resulted in the ground <span class="hlt">magnetic</span> data was conducted for <span class="hlt">magnetic</span> elements exploration. Firstly, RTP technique was applied for recognizing underground <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>. RTP <span class="hlt">anomalies</span> was classified to different populations based on this method. For this reason, drilling points determination with RTP technique was complicated. Next, C-A method was applied on the RTP-<span class="hlt">Magnetic-Anomalies</span> (RTP-MA) for demonstrating <span class="hlt">magnetic</span> susceptibility concentration. This identification was appropriate for increasing the resolution of the drilling points determination and decreasing the drilling risk, due to the economic costs of underground prospecting. In this study, the results of C-A Modeling on the RTP-MA are compared with 8 borehole data. The results show there is good correlation between <span class="hlt">anomalies</span> derived via C-A method and log report of boreholes. Two boreholes were drilled in <span class="hlt">magnetic</span> susceptibility concentration, based on multifractal modeling data analyses, between 63 533.1 and 66 296 nT. Drilling results show appropriate magnetite thickness with the grades greater than 20 % Fe total. Also, <span class="hlt">anomalies</span> associated with andesite units host iron mineralization.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19960039926','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19960039926"><span id="translatedtitle">Investigation of source location determination from Magsat <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>: The Euler method approach</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ravat, Dhananjay</p> <p>1996-01-01</p> <p>The applicability of the Euler method of source location determination was investigated on several model situations pertinent to satellite-data scale situations as well as Magsat data of Europe. Our investigations enabled us to understand the end-member cases for which the Euler method will work with the present satellite <span class="hlt">magnetic</span> data and also the cases for which the assumptions implicit in the Euler method will not be met by the present satellite <span class="hlt">magnetic</span> data. These results have been presented in one invited lecture at the Indo-US workshop on Geomagnetism in Studies of the Earth's Interior in August 1994 in Pune, India, and at one presentation at the 21st General Assembly of the IUGG in July 1995 in Boulder, CO. A new method, called <span class="hlt">Anomaly</span> Attenuation Rate (AAR) Method (based on the Euler method), was developed during this study. This method is scale-independent and is appropriate to locate centroids of semi-compact three dimensional sources of gravity and <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>. The method was presented during 1996 Spring AGU meeting and a manuscript describing this method is being prepared for its submission to a high-ranking journal. The grant has resulted in 3 papers and presentations at national and international meetings and one manuscript of a paper (to be submitted shortly to a reputable journal).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015MeScT..26a5008L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015MeScT..26a5008L"><span id="translatedtitle">Adaptive cancellation of geomagnetic background noise for <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> detection using coherence</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, Dunge; Xu, Xin; Huang, Chao; Zhu, Wanhua; Liu, Xiaojun; Yu, Gang; Fang, Guangyou</p> <p>2015-01-01</p> <p><span class="hlt">Magnetic</span> <span class="hlt">anomaly</span> detection (MAD) is an effective method for the detection of ferromagnetic targets against background <span class="hlt">magnetic</span> fields. Currently, the performance of MAD systems is mainly limited by the background geomagnetic noise. Several techniques have been developed to detect target signatures, such as the synchronous reference subtraction (SRS) method. In this paper, we propose an adaptive coherent noise suppression (ACNS) method. The proposed method is capable of evaluating and detecting weak <span class="hlt">anomaly</span> signals buried in background geomagnetic noise. Tests with real-world recorded <span class="hlt">magnetic</span> signals show that the ACNS method can excellently remove the background geomagnetic noise by about 21 dB or more in high background geomagnetic field environments. Additionally, as a general form of the SRS method, the ACNS method offers appreciable advantages over the existing algorithms. Compared to the SRS method, the ACNS algorithm can eliminate the false target signals and represents a noise suppressing capability improvement of 6.4 dB. The positive outcomes in terms of intelligibility make this method a potential candidate for application in MAD systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EP%26S...68...27L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EP%26S...68...27L"><span id="translatedtitle">Building the second version of the World Digital <span class="hlt">Magnetic</span> <span class="hlt">Anomaly</span> Map (WDMAM)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lesur, Vincent; Hamoudi, Mohamed; Choi, Yujin; Dyment, Jérôme; Thébault, Erwan</p> <p>2016-02-01</p> <p>The World Digital <span class="hlt">Anomaly</span> Map (WDMAM) is a worldwide compilation of near-surface <span class="hlt">magnetic</span> data. We present here a candidate for the second version of the WDMAM and its characteristics. This candidate has been evaluated by a group of independent reviewers and has been adopted as the official second version of the WDMAM during the 26th general assembly of the International Union of Geodesy and Geomagnetism (IUGG). The way this compilation has been built is described with some details. A global <span class="hlt">magnetic</span> field model of the lithosphere contribution, parameterised by spherical harmonics, has been derived up to degree and order 800. The model information content has been evaluated by computing local spectra. Further, the compatibility of the <span class="hlt">anomaly</span> field displayed by the WDMAM with a pure induced magnetisation is tested by comparison with the main field strength. These studies allowed an analysis of the compilation in terms of strength and wavelength content. They confirm the extremely smooth and weak contribution of the <span class="hlt">magnetic</span> field generated in the lithosphere over Western Europe. This apparent weakness possibly extends to the Northern African continent. However, a global analysis remains difficult to achieve given the sparseness of good quality data over very large area of oceans and continents. The WDMAM and related information can be downloaded at http://www.wdmam.org/.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1715430D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1715430D"><span id="translatedtitle">Release of the World Digital <span class="hlt">Magnetic</span> <span class="hlt">Anomaly</span> Map version 2 (WDMAM v2) scheduled</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dyment, Jérôme; Lesur, Vincent; Choi, Yujin; Hamoudi, Mohamed; Thébault, Erwan; Catalan, Manuel</p> <p>2015-04-01</p> <p>The World Digital <span class="hlt">Magnetic</span> <span class="hlt">Anomaly</span> Map is an international initiative carried out under the auspices of the International Association of Geomagnetism and Aeronomy (IAGA) and the Commission for the Geological Map of the World (CGMW). A first version of the map has been published and distributed eight years ago (WDMAM v1; Korhonen et al., 2007). After a call for an improved second version of the map in 2011, the slow process of data compilation, map preparation, evaluation and finalization is near completion, and the WDMAM v2 will be released at the International Union of Geophysics and Geodesy (IUGG) meeting to be held in Prag in June-July 2015. In this presentation we display several shortcomings of the WDMAM v1, both on continental and oceanic areas, that are hopefully alleviated in the WDMAM v2, and discuss the process leading to the new map. We reiterate a long-standing call for aeromagnetic and marine <span class="hlt">magnetic</span> data contribution, and explore future directions to pursue the effort toward a more complete, higher resolution <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> map of the World.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFM.T23B2259Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.T23B2259Z"><span id="translatedtitle">Processing and interpretation for Gravity and <span class="hlt">Magnetic</span> <span class="hlt">Anomalies</span> in the Daba Mountain and Periphery Areas</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, J.; Gao, R.; Li, Q.; Zhang, S.; Guan, Y.; Wang, H.</p> <p>2010-12-01</p> <p>Between Yangxian and Xiangfan the Dabashan nappe structural belt links the Hannan block west and the Huangling block east. The Dabashan bow-like folding belt was formed during late Jurassic and superposed on Triassic folds. To achieve an improved overall understanding of the deep tectonics of the Dabashan nappe structural belt, with new deep reflected seismic and other geophysical data as constraints, we processed and interpreted the gravity and <span class="hlt">magnetic</span> data in this area. The result shows that the Sichuan basin and Daba mountain lie in between the Longmenshan gravity gradient belt and Wulingshan gravity gradient belt. The positive <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> around the Nanchong-Tongjiang-Wanyuan-Langao and the Shizhu are caused by the crystalline basement. The modeling of the gravity and <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> in the Daba mountain and adjacent area shows that the crystalline basementt around the Nanchong-Tongjiang-Wanyuan-Langao stretches approximately underneath the Wafangdian fault near the Ziyang in the direction of northeast. The <span class="hlt">magnetic</span> field boundary along the Zhenba-Wanyuan-Chengkou-Zhenping indicates the location of the major boundary of the Dabashan nappe thrusting above the Sichuan Basin. This boundary might be the division between the south Dabashan structural element and the north Dabashan structural element. The low gravity <span class="hlt">anomaly</span> between the Tongjiang and Chengkou might be partly caused by the thickened lower crust. The local low gravity <span class="hlt">anomaly</span> to the south of Chengkou-Wanyuan might be mainly caused by the Mesozoic strata of low density in the Dabashan foreland depression. The Moho uplifts gently from the center of the Sichuan Basin to the Daba mountain. But the shape of the Moho is not the enantiomorph approximately with the corresponding topography of the Daba mountain. This implies that the Daba mountain is not isostatically compensated on a local scale according to the classical isostatical theory. The evidence reveals that the intra-continent subduction in Dabieshan, Dabashan and other places in central China occurred in Late Jurassic. The isostatical compensation should have been finished during the long period of time. This phenomenon will be studied in virtue of the modern isostatical theory. This work was supported by Crust Probe Project of China (SINOPROBE-02, SINOPROBE-08-02), the Natural Science Foundation of China (Nos. 40830316, 40774026, 40874045 ), China Geological Survey (Nos. 1212010611809, 1212010711813, 1212010811033), scientific research project for public welfare from the Ministry of Land and Resources of China (No. 200811021), and the Basic outlay of scientific research work from the Ministry of Science and Technology of China (No. J0803).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016IJMPA..3150074D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016IJMPA..3150074D"><span id="translatedtitle">A semiclassical formulation of the chiral <span class="hlt">magnetic</span> effect and chiral <span class="hlt">anomaly</span> in even d + 1 dimensions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dayi, Ömer F.; Elbistan, Mahmut</p> <p>2016-05-01</p> <p>In terms of the matrix valued Berry gauge field strength for the Weyl Hamiltonian in any even space-time dimensions a symplectic form whose elements are matrices in spin indices is introduced. Definition of the volume form is modified appropriately. A simple method of finding the path integral measure and the chiral current in the presence of external electromagnetic fields is presented. It is shown that within this new approach the chiral <span class="hlt">magnetic</span> effect as well as the chiral <span class="hlt">anomaly</span> in even d + 1 dimensions are accomplished straightforwardly.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AdSpR..37.1777K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AdSpR..37.1777K"><span id="translatedtitle">Interplanetary origin of <span class="hlt">magnetic</span> storms and their F2-region responses at the equatorial <span class="hlt">anomaly</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kumar, S.; Sharma, S.; Chandra, H.</p> <p></p> <p>The interplanetary origin of 102 storms (Dst ⩽ -50 nT) of varying strength that occurred during the period of 1997 2001, have been studied. The shock compression, <span class="hlt">magnetic</span> clouds, and shock compression followed by <span class="hlt">magnetic</span> clouds are most probable sources of intense southward component BS of IMF in the interplanetary medium causing the <span class="hlt">magnetic</span> storms. Thirty five percent of <span class="hlt">magnetic</span> storms were associated with the <span class="hlt">magnetic</span> clouds. The main phase of 60% intense and very intense <span class="hlt">magnetic</span> storms associated with the <span class="hlt">magnetic</span> clouds, occurred through the multi-step growth in the ring current during the main phase evolution of the storms. The storms were associated with enhanced IMF intensity, proton bulk velocity, ion dynamic pressure and ion density, in the solar wind, in general, with increase in strength of the storms, but not linearly. The storm-time effects in the ionospheric F2-region during 51 <span class="hlt">magnetic</span> storms during 1997 2001, at Ahmedabad (23.2°N, 72.4°E, dip angle 30.7° at sub-ionospheric points), a station at the ionization <span class="hlt">anomaly</span> crest in the Indian region, are also studied. The negative ionospheric effects are more pronounced than the positive ionospheric effects. While the prompt penetration of high-latitude electric fields and the electric fields generated by the disturbance dynamo play important role in F2-region response by changing E × B drifts at low latitude, the storm-induced transport of gas with depleted ratio of [O]/[N2] may also be responsible for the post-midnight large decrease in foF2, during strong <span class="hlt">magnetic</span> storms (Dst < 100 nT).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PApGe.tmp..141A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PApGe.tmp..141A"><span id="translatedtitle">A least-squares minimization approach for model parameters estimate by using a new <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> formula</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Abo-Ezz, E. R.; Essa, K. S.</p> <p>2015-09-01</p> <p>A new linear least-squares approach is proposed to interpret <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> of the buried structures by using a new <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> formula. This approach depends on solving different sets of algebraic linear equations in order to invert the depth (z), amplitude coefficient (K), and <span class="hlt">magnetization</span> angle (θ) of buried structures using <span class="hlt">magnetic</span> data. The utility and validity of the new proposed approach has been demonstrated through various reliable synthetic data sets with and without noise. In addition, the method has been applied to field data sets from USA and India. The best-fitted <span class="hlt">anomaly</span> has been delineated by estimating the root-mean squared (rms). Judging satisfaction of this approach is done by comparing the obtained results with other available geological or geophysical information.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PApGe.173.1265A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PApGe.173.1265A"><span id="translatedtitle">A least-squares minimization approach for model parameters estimate by using a new <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> formula</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Abo-Ezz, E. R.; Essa, K. S.</p> <p>2016-04-01</p> <p>A new linear least-squares approach is proposed to interpret <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> of the buried structures by using a new <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> formula. This approach depends on solving different sets of algebraic linear equations in order to invert the depth ( z), amplitude coefficient ( K), and <span class="hlt">magnetization</span> angle ( θ) of buried structures using <span class="hlt">magnetic</span> data. The utility and validity of the new proposed approach has been demonstrated through various reliable synthetic data sets with and without noise. In addition, the method has been applied to field data sets from USA and India. The best-fitted <span class="hlt">anomaly</span> has been delineated by estimating the root-mean squared (rms). Judging satisfaction of this approach is done by comparing the obtained results with other available geological or geophysical information.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/ofr20071047SRP006','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/ofr20071047SRP006"><span id="translatedtitle"><span class="hlt">Magnetic</span> <span class="hlt">anomalies</span> in East Antarctica: a window on major tectonic provinces and their boundaries</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Golynsky, A.V.</p> <p>2007-01-01</p> <p>An analysis of aeromagnetic data compiled within the Antarctic Digital <span class="hlt">Magnetic</span> <span class="hlt">Anomaly</span> Project (ADMAP) yields significant new insight into major tectonic provinces of East Antarctica. Several previously unknown crustal blocks are imaged in the deep interior of the continent, which are interpreted as cratonic nuclei. These cratons are fringed by a large and continuous orogenic belt between Coats Land and Princess Elizabeth Land, with possible branches in the deeper interior of East Antarctica. Most of the crustal provinces and boundaries identified in this study are only in part exposed. More detailed analyses of these crustal provinces and their tectonic boundaries would require systematic acquisition of additional high-resolution <span class="hlt">magnetic</span> data, because at present the ADMAP database is largely inadequate to address many remaining questions regarding Antarctica’s tectonic evolution.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25823983','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25823983"><span id="translatedtitle"><span class="hlt">Magnetic</span> diffusion <span class="hlt">anomaly</span> at the Néel temperature of pyrrhotite, Fe(1-x)S.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>William Herbert, F; Krishnamoorthy, Aravind; Rands, Lucy; Van Vliet, Krystyn J; Yildiz, Bilge</p> <p>2015-04-28</p> <p>Cation diffusion is an important rate-limiting process in the growth of pyrrhotite (Fe1-xS) in passivating films on steels exposed to sulfidic environments, and for proposed synthetic applications of Fe1-xS, for example single-phase <span class="hlt">magnetic</span> switching devices. Above the Néel temperature TN of 315 °C, where Fe1-xS is paramagnetic and structurally disordered, iron self-diffusivity *DFe predictably follows a standard, established Arrhenius law with temperature. However, we report (57)Fe tracer diffusion measurements below TN, obtained using secondary ion mass spectrometry (SIMS), that demonstrate a 100-fold reduction in diffusion coefficient as compared to the extrapolated, paramagnetic Arrhenius trend at 150 °C. The results can be described by a <span class="hlt">magnetic</span> diffusion <span class="hlt">anomaly</span>, where the vacancy migration energy for the spontaneously-<span class="hlt">magnetized</span> cation sublattice is increased by approximately 40% over the paramagnetic state. These constitute the first set of consistent diffusivity data obtained in <span class="hlt">magnetic</span> pyrrhotite, allowing more accurate prediction of pyrrhotite growth rates and determination of <span class="hlt">magnetic</span> properties for synthetic devices. PMID:25823983</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19990115917&hterms=geological&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dgeological','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19990115917&hterms=geological&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dgeological"><span id="translatedtitle">A Review of <span class="hlt">Magnetic</span> <span class="hlt">Anomaly</span> Field Data for the Arctic Region: Geological Implications</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Taylor, Patrick T.; vonFrese, Ralph; Roman, Daniel; Frawley, James J.</p> <p>1999-01-01</p> <p>Due to its inaccessibility and hostile physical environment remote sensing data, both airborne and satellite measurements, has been the main source of geopotential data over the entire Arctic region. Ubiquitous and significant external fields, however, hinder crustal <span class="hlt">magnetic</span> field studies. These potential field data have been used to derive tectonic models for the two major tectonic sectors of this region, the Amerasian and Eurasian Basins. The latter is dominated by the Nansen-Gakkel or Mid-Arctic Ocean Ridge and is relatively well known. The origin and nature of the Alpha and Mendeleev Ridges, Chukchi Borderland and Canada Basin of the former are less well known and a subject of controversy. The Lomonosov Ridge divides these large provinces. In this report we will present a summary of the Arctic geopotential <span class="hlt">anomaly</span> data derived from various sources by various groups in North America and Europe and show how these data help us unravel the last remaining major puzzle of the global plate tectonic framework. While <span class="hlt">Magnetic</span> <span class="hlt">anomaly</span> data represent the main focus of this study recently derived satellite gravity data (Laxon and McAdoo, 1998) are playing a major role in Arctic studies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19990117091&hterms=geological&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dgeological','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19990117091&hterms=geological&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dgeological"><span id="translatedtitle">A Review of <span class="hlt">Magnetic</span> <span class="hlt">Anomaly</span> Field Data for the Arctic Region: Geological Implications</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Taylor, Patrick T.; vonFrese, Ralph; Roman, Daniel; Frawley, James J.</p> <p>1999-01-01</p> <p>Due to its inaccessibility and hostile physical environment remote sensing data, both airborne and satellite measurements, has been the main source of geopotential data over the entire Arctic region. Ubiquitous and significant external fields, however, hinder crustal <span class="hlt">magnetic</span> field studies These potential field data have been used to derive tectonic models for the two major tectonic sectors of this region, the Amerasian and Eurasian Basins. The latter is dominated by the Nansen-Gakkel or Mid-Arctic Ocean Ridge and is relatively well known. The origin and nature of the Alpha and Mendeleev Ridges, Chukchi Borderland and Canada Basin of the former are less well known and a subject of controversy. The Lomonosov Ridge divides these large provinces. In this report we will present a summary of the Arctic geopotential <span class="hlt">anomaly</span> data derived from various sources by various groups in North America and Europe and show how these data help us unravel the last remaining major puzzle of the global plate tectonic framework. While <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> data represent the main focus of this study recently derived satellite gravity data are playing a major role in Arctic studies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ExG....47...58A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ExG....47...58A"><span id="translatedtitle">Depth and shape solutions from second moving average residual <span class="hlt">magnetic</span> <span class="hlt">anomalies</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Abdelrahman, El-Sayed M.; Essa, Khalid S.; El-Araby, Tarek M.; Abo-Ezz, Eid R.</p> <p>2016-02-01</p> <p>We have developed a simple and fast numerical method to simultaneously determine the depth and shape of a buried structure from second moving average residual <span class="hlt">anomalies</span> obtained from <span class="hlt">magnetic</span> data with filters of successive window lengths. The method is similar to Euler deconvolution, but it solves for depth and shape independently. The method involves using a nonlinear relationship between the depth to the source and the shape factor, and a combination of observations at five points with respect to the coordinate of the source centre with a free parameter (window length). The method is based on computing the standard deviation of the depths determined from all second moving average residual <span class="hlt">anomalies</span> for each value of the shape factor. The standard deviation may generally be considered a criterion for determining the correct depth and shape of the buried structure. When the correct shape factor is used, the standard deviation of the depths is less than the standard deviation using incorrect values of the shape factor. This method can be applied to residuals, as well as the observed <span class="hlt">magnetic</span> data consisting of the combined effect of a residual component due to a purely local structure and a regional component represented by a polynomial of up to fourth-order. The method is applied to synthetic data, with and without random errors, and tested on a field example from Brazil. In all cases, the shape and depth of the buried structures are found in good agreement with the actual ones.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JGRB..120.5983M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JGRB..120.5983M"><span id="translatedtitle">Gravimetric and <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> produced by dissolution-crystallization at the core-mantle boundary</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mandea, Mioara; Narteau, Clément; Panet, Isabelle; Le Mouël, Jean-Louis</p> <p>2015-09-01</p> <p>Using the unique data sets provided by satellite observations, correlated temporal variations in gravity and <span class="hlt">magnetic</span> fields over a large area extending from the Atlantic to the Indian Ocean have been recently reported. On a timescale of few years to a decade, both field variations may be linked to changes at the top of the core. Here we propose that in addition to the topography generated by the convection in the mantle, the core-mantle boundary (CMB) may be in a dynamic equilibrium state, mainly controlled by a dissolution-crystallization process of the mantle silicate rocks in the liquid alloy of the core. Due to the resulting continuous changes in CMB topography, <span class="hlt">anomalies</span> of hundreds of nGal and tens of nT yr-2 might be produced by the corresponding mass redistribution and the secondary flow generated by the associated pressure field. Numerical modeling and both gravimetric and <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> magnitudes suggest a rate of centimeters per year and a large range of length scales for the changes in the topography at the CMB.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFMGP33B..02M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFMGP33B..02M"><span id="translatedtitle">Long-Wavelength <span class="hlt">Magnetic</span> <span class="hlt">Anomalies</span> and Tectonic Divisions of the Tasmanides, Eastern Australia.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Musgrave, R. J.</p> <p>2011-12-01</p> <p>Aeromagnetic data over eastern Australia reveal a pattern of domains defined by systematic and uniform regional highs and lows, emphasised by low-pass filtering, over which are superimposed shorter (<20 km) wavelength <span class="hlt">anomalies</span> whose disposition is clearly related to mappable geology and its inferred subsurface continuation. Long baseline levelling accomplished through Geoscience Australia's AWAGS program has served to clarify the definition of these <span class="hlt">magnetic</span> domains, and to confirm that they are not an artefact of grid merging. Geothermal and teleseismic data indicate that neither variation in Curie depth nor upper mantle magnetisation can produce the pattern of long-wavelength <span class="hlt">magnetic</span> domains. Hence, domain-wide variations in magnetisation at the middle crustal (> 10 km depth) level are presumably the cause of these long-wavelength features. Although reversed polarity remanence, possibly carried by laminar hematite, could contribute to deeply sourced negative <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>, the correspondence of <span class="hlt">magnetic</span> low domains with the Proterozoic Curnamona Craton and the Ordovician Macquarie Arc, and of a high domain with the western Lachlan Orogen floored by Cambrian ocean crust, suggests that the control may be simply stark contrasts in lower to middle crustal susceptibility. Implicit in this analysis is a division of the domains by middle crust type into two categories, continental versus oceanic, with implications for the tectonic evolution of the Tasmanides. Contrary to previous interpretations, the Macquarie Arc was apparently built on a sliver of continental crust, and the Thomson Orogen is a compound feature, in which oceanic crust was accreted to an arc likewise floored by continental material.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4208775','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4208775"><span id="translatedtitle">Energy Detection Based on Undecimated Discrete Wavelet Transform and Its Application in <span class="hlt">Magnetic</span> <span class="hlt">Anomaly</span> Detection</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Nie, Xinhua; Pan, Zhongming; Zhang, Dasha; Zhou, Han; Chen, Min; Zhang, Wenna</p> <p>2014-01-01</p> <p><span class="hlt">Magnetic</span> <span class="hlt">anomaly</span> detection (MAD) is a passive approach for detection of a ferromagnetic target, and its performance is often limited by external noises. In consideration of one major noise source is the fractal noise (or called 1/f noise) with a power spectral density of 1/fa (0<a<2), which is non-stationary, self-similarity and long-range correlation. Meanwhile the orthonormal wavelet decomposition can play the role of a Karhunen-Loève-type expansion to the 1/f-type signal by its decorrelation abilities, an effective energy detection method based on undecimated discrete wavelet transform (UDWT) is proposed in this paper. Firstly, the foundations of <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> detection and UDWT are introduced in brief, while a possible detection system based on giant magneto-impedance (GMI) <span class="hlt">magnetic</span> sensor is also given out. Then our proposed energy detection based on UDWT is described in detail, and the probabilities of false alarm and detection for given the detection threshold in theory are presented. It is noticeable that no a priori assumptions regarding the ferromagnetic target or the <span class="hlt">magnetic</span> noise probability are necessary for our method, and different from the discrete wavelet transform (DWT), the UDWT is shift invariant. Finally, some simulations are performed and the results show that the detection performance of our proposed detector is better than that of the conventional energy detector even utilized in the Gaussian white noise, especially when the spectral parameter α is less than 1.0. In addition, a real-world experiment was done to demonstrate the advantages of the proposed method. PMID:25343484</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_12 --> <div id="page_13" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="241"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..1512353E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..1512353E"><span id="translatedtitle">Spatial Correlation of Airborne <span class="hlt">Magnetic</span> <span class="hlt">Anomalies</span> with Reservoir Temperatures of Geothermal Fields, Western Anatolia, Turkey</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ertekin, Can; Ekinci, Yunus Levent</p> <p>2013-04-01</p> <p>Geothermal areas in Western Anatolia are remarkably located throughout Büyük Menderes Graben (BMG) and Gediz Graben (GG). These E-W trending grabens have been subjected to N-E stretching since Miocene. Except for these major outcomes of the extensional forces, NE-SW oriented and relatively short grabens take place in Western Anatolia as well. Among them, BMG and GG are remarkable with topographic escarpments that reveal footwall of steeply-dipping active normal faults. They manifest themselves via numerous earthquakes and geothermal activity (fluid discharges from springs and wells). Geothermal discharges are aligned along the rims of E-W trending normal faults trending over detachment faults. Concerning BMG, geothermal manifestations extend along the northern sector of the graben. Geothermal reservoirs inside BMG are the limestone and conglomerate units within Neogene sediments and the marble-quartzite units within The Menderes Massif rocks. The main high and low enthalpy geothermal fields along BMG and their reservoir temperatures are as follows: Kızıldere (242°C), Germencik (232°C), Aydın-Ilıcabası (101°C), Yılmazköy (142°C), Salavatlı (171°C), Söke (26°C), Pamukkale (36°C), Karahayıt (59°C), Gölemezli (101°C) and Yenice (70°C). Through GG, reservoir temperatures decrease from east to west. Geothermal reservoirs inside GG are metamorphics and granodiorite of the Menderes Massif rocks. The Neogene sediments act as cap rock of the geothermal reservoirs. Geothermal fields inside the graben and their reservoir temperatures are as follows: Alaşehir (215°C), Salihli (155°C), Urganlı (85°C), Kurşunlu (135°C), Caferbey (150°C), Sart (100°C). In order to investigate the spatial correlation of <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> and the reservoir temperatures of geothermal fields in the region, we analysed airborne <span class="hlt">magnetic</span> data which were collected by General Directorate of Mineral Research and Exploration (MTA) of Turkey. Airborne <span class="hlt">magnetic</span> data were taken at about 70-m intervals along the profiles and the profile interval was set as 1-2 km. Necessary corrections including the IGRF correction were carried out by MTA. After removing the horizontal planar trend and regional background, a reduction to the pole process was performed to residual <span class="hlt">magnetic</span> data. The pole reduced <span class="hlt">magnetic</span> intensity values vary in the range of -368 and 395 nT in the image map. In general, relatively high amplitude <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> zones indicate the geothermal fields having higher reservoir temperatures than 200°C in the region. On the other hand, moderate <span class="hlt">magnetic</span> intensity values point geothermal fields having lower reservoir temperatures than 200°C. It can be inferred that higher and moderate <span class="hlt">magnetic</span> intensity values in the region are positively and spatially in accordance with higher and lower geothermal reservoir temperatures relative to 200°C. Consequently, obtained results were discussed in terms of <span class="hlt">magnetic</span> intensity, geothermal heat source and geothermal reservoir temperatures. Keywords: <span class="hlt">Magnetic</span> <span class="hlt">Anomalies</span>, Reservoir Temperatures, Geothermal Fields, Western Anatolia, Turkey</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..15.4407S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15.4407S"><span id="translatedtitle">3D Geophysical Modelling of the Beattie <span class="hlt">Magnetic</span> <span class="hlt">Anomaly</span> and Karoo Basin, South Africa</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Scheiber-Enslin, Stephanie; Ebbing, Jörg; Eberle, Detlef; Webb, Susan</p> <p>2013-04-01</p> <p>The Karoo Basin, the broad arid plateau that covers much of the interior of South Africa, is supported by the stable Archean Kaapvaal Craton in the north and several surrounding Proterozoic basement blocks in the south, and formed within the continental interior of Gondwana during the Late Carboniferous (300 Ma) to Middle Jurassic (125 Ma). No clear tectonic model exists for the Karoo Basin, with several hypotheses regarding the nature of the subsidence resulting in basin formation. To the southern edge of the Karoo basin the enigmatic Beattie <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> (BMA) is seen, which stretches east to west for ~1000 km across a large portion of South Africa, and for which a variety of explanations have been proposed. Here we present detailed 2D gravity and <span class="hlt">magnetic</span> models across the southwestern Karoo along with a combined first-order regional 3D model. The models presented here are based on seismic and potential field data, along with geological and structural information that cover the entire basin. Information about the Moho structure was derived from teleseismic data. The models have been further constrained using deep boreholes, as well as on- and off-shore seismic lines, Magnetotelluric data, and <span class="hlt">magnetic</span> depth-to-basement estimates. Density and susceptibility values are based on borehole and hand sample data, as well as on the conversion of p-wave seismic velocity to densities. In order to produce an accurate potential field model of the Karoo basin and to understand the evolution of the basin, a clear understanding is needed of the source of the Beattie. Seismic data over the western section of the Beattie <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> place the source in the mid-crust (10-15 km). Earlier studies have attributed the <span class="hlt">anomaly</span> to partially serpentinized oceanic lithosphere possibly linked to a suture zone, or to massive disseminate magnetite-sulphide bodies within the basement. However, our analysis lets us support the idea that the BMA is part of the tectono-metamorphic Namaqua-Natal Mobile Belt and associated shear zones.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ExG....46...19S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ExG....46...19S"><span id="translatedtitle">The analysis of ZTEM data across the Humble <span class="hlt">magnetic</span> <span class="hlt">anomaly</span>, Alaska</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sattel, Daniel; Witherly, Ken</p> <p>2015-09-01</p> <p>ZTEM data acquired across the Humble <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> of almost 30 000 nT were analysed for the presence of a <span class="hlt">magnetic</span> gradient response and the effects from elevated <span class="hlt">magnetic</span> susceptibilities. Mag3D inversion of the <span class="hlt">magnetic</span> data indicates <span class="hlt">magnetic</span> susceptibility values as high as 2.0 (SI). The response of moving the receiver coil through the <span class="hlt">magnetic</span>-field gradient peaks at 0.01 Hz and drops off strongly with frequency. Lacking information about the field strength at the base station precludes the comparison of amplitudes between computed gradient responses and the survey data, but the comparison of response shapes suggests that the gradient responses are too small to have a noticeable effect on the survey data. ZTEM responses were forward modelled with a 3D algorithm developed at the University of British Columbia Geophysical Inversion Facility (UBC-GIF) that takes into account electric conductivities σ and <span class="hlt">magnetic</span> susceptibilities κ, in order to assess the impact of the elevated κ-values derived from the Mag3D inversion. Computing the ZTEM response for these κ-values combined with resistive half-spaces indicates that the response amplitudes and shapes strongly depend on the background resistivities. Ignoring the elevated κ-values during an inversion can result in patterns that resemble crop circles. The approximate conductivity structure of the survey area was derived with a UBC-GIF 3D ZTEM inversion, which models κ = 0. Forward-model results of these conductivities combined with the elevated κ-values derived from the Mag3D inversion indicate that the conductivities are underestimated with the κ = 0 assumption. For an environment such as Humble, with deep-seated zones of elevated κ-values, the shallow inverted conductivity structure appears to be reliable, but the deeper structure should be interpreted with caution.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014ChPhC..38j7008H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014ChPhC..38j7008H"><span id="translatedtitle">A permanent <span class="hlt">magnet</span> electron beam <span class="hlt">spread</span> system used for a low energy electron irradiation accelerator</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Huang, Jiang; Xiong, Yong-Qian; Chen, De-Zhi; Liu, Kai-Feng; Yang, Jun; Li, Dong; Yu, Tiao-Qin; Fan, Ming-Wu; Yang, Bo</p> <p>2014-10-01</p> <p>The development of irradiation processing industry brings about various types of irradiation objects and expands the irradiation requirements for better uniformity and larger areas. This paper proposes an innovative design of a permanent <span class="hlt">magnet</span> electron beam <span class="hlt">spread</span> system. By clarifying its operation principles, the author verifies the feasibility of its application in irradiation accelerators for industrial use with the examples of its application in electron accelerators with energy ranging from 300 keV to 1 MeV. Based on the finite element analyses of electromagnetic fields and the charged particle dynamics, the author also conducts a simulation of electron dynamics in <span class="hlt">magnetic</span> field on a computer. The results indicate that compared with the traditional electron beam scanning system, this system boosts the advantages of a larger <span class="hlt">spread</span> area, non-power supply, simple structure and low cost, etc., which means it is not only suitable for the irradiation of objects with the shape of tubes, strips and panels, but can also achieve a desirable irradiation performance on irregular constructed objects of large size.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/897563','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/897563"><span id="translatedtitle"><span class="hlt">Magnetization</span> <span class="hlt">anomaly</span> of Nb3Al strands and instability of Nb3Al Rutherford cables</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Yamada, Ryuji; Kikuchi, Akihiro; Wake, Masayoshi; /KEK, Tsukuba</p> <p>2006-08-01</p> <p>Using a Cu stabilized Nb{sub 3}Al strand with Nb matrix, a 30 meter long Nb{sub 3}Al Rutherford cable was made by a collaboration of Fermilab and NIMS. Recently the strand and cable were tested. In both cases instability was observed at around 1.5 Tesla. The <span class="hlt">magnetization</span> of this Nb{sub 3}Al strand was measured first using a balanced coil magnetometer at 4.2 K. Strands showed an anomalously large <span class="hlt">magnetization</span> behavior around at 1.6 T, which is much higher than the usual B{sub c2} {approx} 0.5 Tesla (4.2 K) of Nb matrix. This result is compared with the <span class="hlt">magnetization</span> data of short strand samples using a SQUID magnetometer, in which a flux-jump signal was observed at 0.5 Tesla, but not at higher field. As a possible explanation for this <span class="hlt">magnetization</span> <span class="hlt">anomaly</span>, the interfilament coupling through the thin Nb films in the strands is suggested. The instability problem observed in low field tests of the Nb{sub 3}Al Rutherford cables is attributed to this effect.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/6085497','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6085497"><span id="translatedtitle">Preparation of <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> profile and contour maps from DOE-NURE aerial survey data. Volume I. Processing procedures</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Tinnel, E.P.; Hinze, W.J.</p> <p>1981-09-01</p> <p>Total intensity <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> data acquired as a supplement to radiometric data in the DOE National Uranium Resource Evaluation (NURE) Program are useful in preparing regional profile and contour maps. Survey-contractor-supplied <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> data are subjected to a multiprocess, computer-based procedure which prepares these data for presentation. This procedure is used to produce the following machine plotted maps of National Topographic Map Series quadrangle units at a 1:250,000 scale: (1) profile map of contractor-supplied <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> data, (2) profile map of high-cut filtered data with contour levels of each profile marked and annotated on the associated flight track, (3) profile map of critical-point data with contour levels indicated, and (4) contour map of filtered and selected data. These quadrangle maps are supplemented with a range of statistical measures of the data which are useful in quality evaluation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUFMGP31A..08S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUFMGP31A..08S"><span id="translatedtitle">Circum-Arctic <span class="hlt">Magnetic</span> <span class="hlt">Anomalies</span> - Challenges of Compilation and the Value of Regional Interpretation in a Frontier Area</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Saltus, R. W.; Gaina, C.; Brown, P. J.</p> <p>2007-12-01</p> <p>Important societal issues are driving increased attention to polar regions. The arctic, in particular, is the focus of scientific studies relating to climate change as well as resource exploration and territorial claims. The news and entertainment media are picking up on polar themes and driving interest within popular culture. Part of the attraction and mystique of the ends of the Earth lies in their relative inaccessibility and harsh environment. These same attributes make it difficult to conduct even basic scientific investigation, and therefore, the arctic remains a scientific frontier in many respects. Delineation of a robust tectonic framework for the top of the world is an essential prerequisite to resource assessment. The difficulty of making direct geologic observations beneath ice and sea requires remote measurement. Regional <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> mapping provides important constraining information for the development of tectonic models for this structurally complex region. In addition to the obvious logistical challenges to detailed <span class="hlt">magnetic</span> field measurement in the high arctic, noise and instability in the <span class="hlt">magnetic</span> field itself at high latitudes presents difficulties. Nevertheless, regional <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> data have been collected over the past 50 years for much of the arctic. The available surveys are diverse in vintage and survey design; the amplitude and frequency content of measured <span class="hlt">anomalies</span> are widely variable. Availability of metadata and other documentation are also inconsistent for these surveys. This leads to significant challenges in constructing accurate regional <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> maps. Preliminary maps from a new international cooperation effort (CAMP-GM, under the direction of Carmen Gaina, Geological Survey of Norway) provide the most consistent view yet of <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> for the tectonically complex arctic basins and surrounding continents. Careful attention to digital compilation details allows the new grids to be mathematically filtered to assist in the regional characterization of <span class="hlt">magnetic</span> domains and boundaries. The frequency content, amplitudes, and patterns of regional <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> provide a window into the tectonic character and structure of the crust. Continental, oceanic, and various types of transitional crust each have a distinctive <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> signature that can be used to define a fundamental tectonic framework of the circum-arctic. Interpretation can be extended by including additional data such as regional bathymetry (an indicator of crustal buoyancy and isostatic equilibrium) and free air gravity (an independent indicator of crustal density balance and composition). Used together with <span class="hlt">magnetic</span> domains these data reveal a composite geodynamic subdivision of the arctic. This subdivision provides a framework for investigations of mineral and energy resource potential, tectonic reconstruction, and long-term climate dynamics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110023400','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110023400"><span id="translatedtitle">Investigation of the Crust of the Pannonian Basin, Hungary Using Low-Altitude CHAMP Horizontal Gradient <span class="hlt">Magnetic</span> <span class="hlt">Anomalies</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Taylor, Patrick T.; Kis, Karoly I.; Puszta, Sandor; Wittmann, Geza; Kim, Hyung Rae; Toronyi, B.</p> <p>2011-01-01</p> <p>The Pannonian Basin is a deep intra-continental basin that formed as part of the Alpine orogeny. It is some 600 by 500 km in area and centered on Hungary. This area was chosen since it has one of the thinnest continental crusts in Europe and is the region of complex tectonic structures. In order to study the nature of the crustal basement we used the long-wavelength <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> acquired by the CHAMP satellite. The SWARM constellation, scheduled to be launched next year, will have two lower altitude satellites flying abreast, with a separation of between ca. 150 to 200 km. to record the horizontal <span class="hlt">magnetic</span> gradient. Since the CHAMP satellite has been in orbit for eight years and has obtained an extensive range of data, both vertically and horizontally there is a large enough data base to compute the horizontal <span class="hlt">magnetic</span> gradients over the Pannonian Basin region using these many CHAMP orbits. We recomputed a satellite <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> map, using the spherical-cap method of Haines (1985), the technique of Alsdorf et al. (1994) and from spherical harmonic coefficients of MF6 (Maus et aI., 2008) employing the latest and lowest altitude CHAMP data. We then computed the horizontal <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> gradients (Kis and Puszta, 2006) in order to determine how these component data will improve our interpretation and to preview what the SW ARM mission will reveal with reference to the horizontal gradient <span class="hlt">anomalies</span>. The gradient amplitude of an 1000 km northeast-southwest profile through our horizontal component <span class="hlt">anomaly</span> map varied from 0 to 0.025 nT/km with twin positive <span class="hlt">anomalies</span> (0.025 and 0.023 nT/km) separated by a sharp <span class="hlt">anomaly</span> negative at o nT/km. Horizontal gradient indicate major <span class="hlt">magnetization</span> boundaries in the crust (Dole and Jordan, 1978 and Cordell and Grauch, 1985). Our gradient <span class="hlt">anomaly</span> was modeled with a twodimensional body and the <span class="hlt">anomaly</span>, of some 200 km, correlates with a 200 km area of crustal thinning in the southwestern Pannonian Basin.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFM.G14A..08A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFM.G14A..08A"><span id="translatedtitle">GEODVEL vs. MORVEL: Comparison of plate motion determined from space geodesy with that determined from <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> and transform azimuths (Invited)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Argus, D.; Demets, C.; Gordon, R. G.</p> <p>2009-12-01</p> <p>To test whether plate velocities averaged over the past two decades equal those averaged over the past 1 to 3 million years, we compare the angular velocities in model GEODVEL against those in MORVEL. GEODVEL is determined from four space geodetic techniques, GPS, SLR, VLBI, and DORIS. In GEODVEL we assume Earth’s center to be (CE) the mass center of solid Earth, and we estimate the velocity of CE assuming that, beside plate motion, the parts of the plate interiors near the late Pleistocene ice sheets are not moving relative to CE. In GEODVEL the uncertainties in plate velocity account for uncertainty in the velocity of CE. GEODVEL differs from prior models of plate velocity from space geodesy partly because the velocity of Earth’s center differs between GEODVEL and the other models and partly because the assignment of sites to plates differs between GEODVEL and the other models. MORVEL is determined mainly from transform azimuths and <span class="hlt">spreading</span> rates estimated from <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> either 0.8 Ma (<span class="hlt">anomaly</span> 1o) or 3.2 Ma (<span class="hlt">anomaly</span> 2A). MORVEL differs from NUVEL-1A in that (1) it includes <span class="hlt">spreading</span> rates and transform azimuths estimated using high-quality observations taken over the past two decades, (2) it excludes data from the Gulf of California and earthquake slip vectors along subduction zones, and (3) it includes distinct east (Nubian) and west (Somalian) plates. In MORVEL the velocity of the plates of the Pacific Ocean relative to the surrounding continental plates depend strongly on the plate circuit (Eurasia)-North America-Nubia-Antarctica-Pacific-(Nazca or Cocos). In MORVEL the uncertainties in plate velocity account for uncertainty in outward displacement of <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>. We compare the angular velocities in three dimensions on a plate-by-plate basis. We are finding, for the nine largest plates, the median difference between the GEODVEL and MORVEL sets of angular velocities to be 0.046 °/Myr, which is up to 5.1 mm/yr along Earth’s surface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/24785022','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24785022"><span id="translatedtitle">Electromagnetic particle-in-cell simulations of the solar wind interaction with lunar <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Deca, J; Divin, A; Lapenta, G; Lembège, B; Markidis, S; Horányi, M</p> <p>2014-04-18</p> <p>We present the first three-dimensional fully kinetic and electromagnetic simulations of the solar wind interaction with lunar crustal <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> (LMAs). Using the implicit particle-in-cell code iPic3D, we confirm that LMAs may indeed be strong enough to stand off the solar wind from directly impacting the lunar surface forming a mini-magnetosphere, as suggested by spacecraft observations and theory. In contrast to earlier magnetohydrodynamics and hybrid simulations, the fully kinetic nature of iPic3D allows us to investigate the space charge effects and in particular the electron dynamics dominating the near-surface lunar plasma environment. We describe for the first time the interaction of a dipole model centered just below the lunar surface under plasma conditions such that only the electron population is <span class="hlt">magnetized</span>. The fully kinetic treatment identifies electromagnetic modes that alter the <span class="hlt">magnetic</span> field at scales determined by the electron physics. Driven by strong pressure anisotropies, the mini-magnetosphere is unstable over time, leading to only temporal shielding of the surface underneath. Future human exploration as well as lunar science in general therefore hinges on a better understanding of LMAs. PMID:24785022</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010E%26PSL.289..433O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010E%26PSL.289..433O"><span id="translatedtitle">Oxfordian magnetostratigraphy of Britain and its correlation to Tethyan regions and Pacific marine <span class="hlt">magnetic</span> <span class="hlt">anomalies</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ogg, James G.; Coe, Angela L.; Przybylski, Piotr A.; Wright, John K.</p> <p>2010-01-01</p> <p>A suite of 11 sections through the Oxfordian (Upper Jurassic) strata in the Dorset and Yorkshire regions of England and the Isle of Skye in Scotland yielded <span class="hlt">magnetic</span> polarity patterns directly calibrated to the ammonite biostratigraphy of the Boreal and the Subboreal faunal provinces. The sections include the leading candidate for the global stratotype (GSSP) for the Callovian-Oxfordian stage boundary. The mean Oxfordian paleomagnetic pole derived from the Dorset and Yorkshire sections is 71.3°N, 172.6°E ( δp = 4.2°, δm = 6.1°). The integrated magneto-biostratigraphic scale is consistent with results from the Sub-Mediterranean faunal province and extends the polarity pattern to the base of the Oxfordian. After adjusting for the estimated durations of ammonite subzones from cycle stratigraphy, the magnetostratigraphy confirms models for marine <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> M30 through to M37, including some of the short-duration features recorded by deep-tow <span class="hlt">magnetic</span> surveys in the western Pacific. The Callovian-Oxfordian boundary (base of Quenstedtoceras mariae Zone) occurs in a normal-polarity zone that is correlated to the youngest part of polarity chron M37n of this extension to the M-sequence.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000JMMM..209..217L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000JMMM..209..217L"><span id="translatedtitle">High-temperature <span class="hlt">magnetization</span> <span class="hlt">anomaly</span> in Co/Ag/Si(1 1 1) ultrathin films</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lin, J. Y.; Tsay, J. S.; Liou, Y.; Yao, Y. D.; Lee, S. F.; Yang, C. S.</p> <p>2000-01-01</p> <p>High-temperature <span class="hlt">magnetic</span> properties of ultrathin Co/Ag/Si(1 1 1) films were studied by surface magneto-optic Kerr effect (SMOKE) in an ultra-high vacuum (UHV) chamber with a background pressure less than 110 -10 Torr. A 6 mono-layer (ML) Co layer was deposited on Si(1 1 1) surface with Ag as a buffer layer with the thickness being varied between 0 and 5.6 ML. Both polar and longitudinal MOKE (P- and LMOKE) were studied as a function of temperature between 300 and 550 K. It is interesting to note that the Kerr intensity of LMOKE for Co/Ag/Si(1 1 1) thin film with Ag thickness of 2.8 and 5.6 ML decreases with increasing temperature and vanishes near 475 K; it shows up again in the opposite direction above 475 K before vanishing again at 550 K. This was not observed for samples with Ag thickness less than 2.8 ML. This indicates that the Ag buffer layer is playing an important role in the variation of <span class="hlt">magnetization</span> of Co at high temperature; in other words, stress or small Co/Co-Ag clusters formed by the diffusion between Ag and Co layer at high temperature may cause the <span class="hlt">magnetization</span> <span class="hlt">anomaly</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PhRvL.112o1102D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PhRvL.112o1102D"><span id="translatedtitle">Electromagnetic Particle-in-Cell Simulations of the Solar Wind Interaction with Lunar <span class="hlt">Magnetic</span> <span class="hlt">Anomalies</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Deca, J.; Divin, A.; Lapenta, G.; Lembège, B.; Markidis, S.; Horányi, M.</p> <p>2014-04-01</p> <p>We present the first three-dimensional fully kinetic and electromagnetic simulations of the solar wind interaction with lunar crustal <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> (LMAs). Using the implicit particle-in-cell code iPic3D, we confirm that LMAs may indeed be strong enough to stand off the solar wind from directly impacting the lunar surface forming a mini-magnetosphere, as suggested by spacecraft observations and theory. In contrast to earlier magnetohydrodynamics and hybrid simulations, the fully kinetic nature of iPic3D allows us to investigate the space charge effects and in particular the electron dynamics dominating the near-surface lunar plasma environment. We describe for the first time the interaction of a dipole model centered just below the lunar surface under plasma conditions such that only the electron population is <span class="hlt">magnetized</span>. The fully kinetic treatment identifies electromagnetic modes that alter the <span class="hlt">magnetic</span> field at scales determined by the electron physics. Driven by strong pressure anisotropies, the mini-magnetosphere is unstable over time, leading to only temporal shielding of the surface underneath. Future human exploration as well as lunar science in general therefore hinges on a better understanding of LMAs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3881731','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3881731"><span id="translatedtitle">The role of <span class="hlt">magnetic</span> resonance imaging in refining the diagnosis of suspected fetal renal <span class="hlt">anomalies</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Abdelazim, Ibrahim Anwar; Belal, Maha Mohamed</p> <p>2013-01-01</p> <p>Objective: This prospective study was designed to detect the role of <span class="hlt">magnetic</span> resonance imaging (MRI) in refining the diagnosis of suspected fetal renal <span class="hlt">anomalies</span> detected during screening sonography. Material and Methods: 54 pregnant women, with suspected fetal renal <span class="hlt">anomalies</span> detected during routine ultrasound screening, were rescanned by MRI to refine the diagnosis of the suspected renal <span class="hlt">anomalies</span>. The pregnancy outcome was examined externally and by postnatal ultrasonography. Results: Fifty-four cases of suspected renal <span class="hlt">anomalies</span> detected during screening sonography of 8400 pregnant women (0.6%), were res-canned by MRI in this study. The MRI gave a similar diagnosis to postnatal ultrasound in 46 cases (16 cases of hydronephrosis, 14 cases of Polycystic Kidney Disease (PCKD), 9 cases of Multicystic Kidney Disease (MCKD), 2 cases of Renal Agensis (RA), 3 cases of single renal cyst and 2 cases of megacystis+hydroureter), while it gave a different diagnosis (false positive) in 6 cases (4 cases of hydronephrosis diagnosed by MRI confirmed to be PCKD by postnatal ultrasound, also, 1 case of MCKD diagnosed by MRI confirmed to be hydronephrosis by postnatal ultrasound and 1 case of RA diagnosed by MRI confirmed to be normal by postnatal ultrasound). The prenatal ultrasound gave a similar diagnosis to postnatal ultrasound in 43 cases (14 cases of hydronephrosis, 13 case of PCKD, 9 cases of MCKD, 2 cases of RA, 3 cases of single renal cyst and 2 case of megacystis+hydroureter), while it gave a different diagnosis (false positive) in 9 cases; 4 cases of hydronephrosis diagnosed by prenatal sonography confirmed to be PCKD by postnatal ultrasound, one case of PCKD+one case of MCKD, and one case of megacystis+hydroureter confirmed to be hydronephrosis by postnatal ultrasound, while one case of MCKD diagnosed by prenatal sonography was confirmed to be PCKD by postnatal ultrasound and one case of RA diagnosed by prenatal ultrasound was confirmed to be normal by postnatal ultrasound. Conclusion: The MRI can be used as a complementary adjunctive modality with excellent tissue contrast, especially in equivocal cases or inconclusive sonographic findings. PMID:24592062</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMNS13B1617O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMNS13B1617O"><span id="translatedtitle">Geophysical Surveying of Shallow <span class="hlt">Magnetic</span> <span class="hlt">Anomalies</span> Using the iPhone Magnetometer</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Opdyke, P.; Dudley, C.; Louie, J. N.</p> <p>2012-12-01</p> <p>This investigation examined whether the 3-axis Hall-effect magnetometer in the Apple iPhone 3GS can function as an effective shallow <span class="hlt">magnetic</span> survey instrument. The xSensor Pro app from Crossbow Systems allows recoding of all three sensor components along with the GPS location, at a frequency of 1.0, 4.0, 16.0, and 32.0 Hz. If the iPhone proves successful in collecting useful <span class="hlt">magnetic</span> data, then geophysicists and especially educators would have a new tool for high-density geophysical mapping. No-contract iPhones that can connect with WiFi can be obtained for about $400, allowing deployment of large numbers of instruments. iPhones with the xSensor Pro app surveyed in parallel with an Overhauser GEM system magnetometer (1 nT sensitivity) to test this idea. Anderson Bay, located on the Pyramid Lake Paiute Reservation, provided a rural survey location free from cultural interference. xSensor Pro, logged each component's intensity and the GPS location at a frequency of four measurements per second. Two Overhauser units functioned as a base unit and a roving unit. The roving unit collected total field at set points located with a handheld GPS. Comparing the total field computed from the iPhone components against that collected by the Overhauser establishes the level of <span class="hlt">anomalies</span> that the iPhone can detect. iPhone total-field measurements commonly vary by 200 nT from point to point, so a spatial-temporal average over 25 seconds produces a smoothed signal for comparison. Preliminary analysis of the iPhone results show that the data do not accurately correlate to the total field collected by the Overhauser for any <span class="hlt">anomaly</span> of less than 200 nT.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20020086497&hterms=hydrothermal&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dhydrothermal','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20020086497&hterms=hydrothermal&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dhydrothermal"><span id="translatedtitle">Controls on Martian Hydrothermal Systems: Application to Valley Network and <span class="hlt">Magnetic</span> <span class="hlt">Anomaly</span> Formation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Harrison, Keith P.; Grimm, Robert E.</p> <p>2002-01-01</p> <p>Models of hydrothermal groundwater circulation can quantify limits to the role of hydrothermal activity in Martian crustal processes. We present here the results of numerical simulations of convection in a porous medium due to the presence of a hot intruded magma chamber. The parameter space includes magma chamber depth, volume, aspect ratio, and host rock permeability and porosity. A primary goal of the models is the computation of surface discharge. Discharge increases approximately linearly with chamber volume, decreases weakly with depth (at low geothermal gradients), and is maximized for equant-shaped chambers. Discharge increases linearly with permeability until limited by the energy available from the intrusion. Changes in the average porosity are balanced by changes in flow velocity and therefore have little effect. Water/rock ratios of approximately 0.1, obtained by other workers from models based on the mineralogy of the Shergotty meteorite, imply minimum permeabilities of 10(exp -16) sq m2 during hydrothermal alteration. If substantial vapor volumes are required for soil alteration, the permeability must exceed 10(exp -15) sq m. The principal application of our model is to test the viability of hydrothermal circulation as the primary process responsible for the broad spatial correlation of Martian valley networks with <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>. For host rock permeabilities as low as 10(exp -17) sq m and intrusion volumes as low as 50 cu km, the total discharge due to intrusions building that part of the southern highlands crust associated with <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> spans a comparable range as the inferred discharge from the overlying valley networks.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMGP34A..04M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMGP34A..04M"><span id="translatedtitle">Remanent and Induced <span class="hlt">Magnetic</span> <span class="hlt">Anomalies</span> over the Bjerkreim-Sokndal Layered Intrusion: Effects from Crystal Fractionation and Magma Recharge</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>McEnroe, S. A.; Brown, L. L.; Robinson, P.</p> <p>2013-12-01</p> <p>The Bjerkreim-Sokndal (BKS) norite-quartz mangerite layered intrusion is part of the early Neoproterozoic Rogaland Anorthosite Province intruded into the Fennoscandian shield in south Norway at ~930 Ma. The BKS is exposed over an area of 230 km2 with a thickness of ~7000m and is of economic interest for hemo-ilmenite, magnetite and apatite deposits. From the point of view of <span class="hlt">magnetic</span> minerals, in the course of fractional crystallization and magma evolution, the ilmenite becomes less Fe3+-rich reflected by a change from ilmenite with hematite exsolution to nearly pure ilmenite. Magnetite starts to crystallize relatively late in the intrusive history, but its crystallization is interrupted by influxes of more primitive magma containing hemo-ilmenite. The variations in aeromagnetic and ground-<span class="hlt">magnetic</span> <span class="hlt">anomalies</span> measured over the BKS can be explained in terms of the <span class="hlt">magnetic</span> properties of NRM, susceptibility, and hysteresis. <span class="hlt">Magnetic</span> properties are correlated with the oxide mineralogy and mineral chemistry. Early layers in the intrusion contain hemo-ilmenite. As the magma evolved and magnetite started to crystallize, this caused a distinct change over the layering from remanence-controlled negative <span class="hlt">anomalies</span> to induced positive <span class="hlt">anomalies</span>. When new, more primitive magma was injected into the system, hemo-ilmenite returned as the major oxide and the resulting <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> are again negative. The most dramatic change in the <span class="hlt">magnetic</span> signature is in the upper part of the intrusion in MCU IVe, where magnetite became a well established cumulate phase as indicated by susceptibility, but its induced <span class="hlt">magnetization</span> is overcome by large NRM's associated either with hemo-ilmenite or with hemo-ilmenite and magnetite exsolved from pyroxenes. The average natural remanent <span class="hlt">magnetizations</span> change from ~3 A/m in MCU IVd, to 15 A/m in MCU IVe, and back to 2 A/m in the overlying MCU IVf, producing a strong negative remanent <span class="hlt">anomaly</span> that has been followed along strike for at least 20 km by ground-<span class="hlt">magnetic</span> measurements. The highly varied <span class="hlt">magnetic</span> properties of this intrusion, caused by varied magmatic crystallization of combinations of oxide minerals illustrate some of the possibilities to be considered in evaluating crustal <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013APS..DPPNO5013J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013APS..DPPNO5013J"><span id="translatedtitle">Current disruption and its <span class="hlt">spreading</span> in collision-less <span class="hlt">magnetic</span> reconnection</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jain, Neeraj; Buechner, Joerg; Dorfman, Seth; Ji, Hantao; Sharma, A. Surjalal; Max-Planck/Princeton CenterPlasma Physics Collaboration</p> <p>2013-10-01</p> <p>Recent <span class="hlt">magnetic</span> reconnection experiments (MRX) [Dorfman et al., Geophys. Res. Lett. 40, 233 (2012)] have disclosed current disruption in the absence of guide field. During current disruption in MRX, current density and total out-of-reconnection-plane current drop simultaneous with a rise in out-of-reconnection-plane electric field. Here we show that current disruption is an intrinsic property of dynamic formation of X-point configuration of <span class="hlt">magnetic</span> field in <span class="hlt">magnetic</span> reconnection, independent of the model used for plasma description and of dimensionality (2-D or 3-D) of reconnection. An analytic expression for the current drop is derived from Ampere's equation and its predictions are verified by 2-D and 3-D electron-magnetohydrodynamic (EMHD) simulations. Three dimensional EMHD simulations show that the current disruption due to localized reconnection <span class="hlt">spreads</span> along the direction of electron flow with a speed which depends on the wave number of the perturbation. The implications of these results for MRX and other reconnection experiments will be presented. This work was partially funded by the Max-Planck/Princeton Center for Plasma Physics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PApGe.172.2701G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PApGe.172.2701G"><span id="translatedtitle">A Hybrid Positive-and-Negative Curvature Approach for Detection of the Edges of <span class="hlt">Magnetic</span> <span class="hlt">Anomalies</span>, and Its Application in the South China Sea</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Guo, Lianghui; Gao, Rui; Meng, Xiaohong; Zhang, Guoli</p> <p>2015-10-01</p> <p>In work discussed in this paper the characteristics of both the most positive and most negative curvatures of a <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> were analyzed, and a new approach for detection of the edges of <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> is proposed. The new approach, called the hybrid positive-and-negative curvature approach, combines the most positive and most negative curvatures into one curvature by formula adjustments and weighted summation, combining the advantages of the two curvatures to improve edge detection. This approach is suitable for vertically <span class="hlt">magnetized</span> or reduction-to-pole <span class="hlt">anomalies</span>, which avoids the complexity of <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> caused by oblique <span class="hlt">magnetization</span>. Testing on synthetic vertically <span class="hlt">magnetized</span> <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> data demonstrated that the hybrid approach traces the edges of <span class="hlt">magnetic</span> source bodies effectively, discriminates between high and low <span class="hlt">magnetism</span> intuitively, and is better than approaches based solely on use of the most positive or most negative curvature. Testing on reduced-to-pole <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> data around the ocean basin of the South China Sea showed that the hybrid approach enables better edge detection than the most positive or most negative curvatures. On the basis of the features of the reduced-to-pole <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> and their hybrid curvature, we suggest the tectonic boundary between the southwestern subbasin and the eastern subbasin of the South China Sea ranges from the northeastern edge of the Zhongsha Islands in the southeast direction to the northeastern edge of the Reed Bank.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016Nanos...8.5200D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016Nanos...8.5200D"><span id="translatedtitle">Observation of <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> in one-step solvothermally synthesized nickel-cobalt ferrite nanoparticles</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Datt, Gopal; Sen Bishwas, Mousumi; Manivel Raja, M.; Abhyankar, A. C.</p> <p>2016-02-01</p> <p><span class="hlt">Magnetic</span> <span class="hlt">anomalies</span> corresponding to the Verwey transition and reorientation of anisotropic vacancies are observed at 151 K and 306 K, respectively, in NiCoFe2O4 nanoparticles (NPs) synthesized by a modified-solvothermal method followed by annealing. Cationic disorder and spherical shape induced non-stoichiometry suppress the Verwey transition in the as-synthesized NPs. On the other hand, reorientation of anisotropic vacancies is quite robust. XRD and electron microscopy investigations confirm a single phase spinel structure and the surface morphology of the as-synthesized NPs changes from spherical to octahedral upon annealing. Rietveld analysis reveals that the Ni2+ ions migrate from tetrahedral (A) to octahedral (B) sites upon annealing. The Mössbauer results show canted spins in both the NPs and the strength of superexchange is stronger in Co-O-Fe than Ni-O-Fe. <span class="hlt">Magnetic</span> force images show that the as-synthesised NPs are single-domain whereas the annealed NPs are multi-domain octahedral particles. The FMR study reveals that both the NPs have a broad FMR line-width; and resonance properties are consistent with the random anisotropy model. The broad inhomogeneous FMR line-width, observation of the Verwey transition, tuning of the <span class="hlt">magnetic</span> domain structure as well as the <span class="hlt">magnetic</span> properties suggest that the NiCoFe2O4 ferrite NPs may be promising for future generation spintronics, magneto-electronics, and ultra-high-density recording media as well as for radar absorbing applications.<span class="hlt">Magnetic</span> <span class="hlt">anomalies</span> corresponding to the Verwey transition and reorientation of anisotropic vacancies are observed at 151 K and 306 K, respectively, in NiCoFe2O4 nanoparticles (NPs) synthesized by a modified-solvothermal method followed by annealing. Cationic disorder and spherical shape induced non-stoichiometry suppress the Verwey transition in the as-synthesized NPs. On the other hand, reorientation of anisotropic vacancies is quite robust. XRD and electron microscopy investigations confirm a single phase spinel structure and the surface morphology of the as-synthesized NPs changes from spherical to octahedral upon annealing. Rietveld analysis reveals that the Ni2+ ions migrate from tetrahedral (A) to octahedral (B) sites upon annealing. The Mössbauer results show canted spins in both the NPs and the strength of superexchange is stronger in Co-O-Fe than Ni-O-Fe. <span class="hlt">Magnetic</span> force images show that the as-synthesised NPs are single-domain whereas the annealed NPs are multi-domain octahedral particles. The FMR study reveals that both the NPs have a broad FMR line-width; and resonance properties are consistent with the random anisotropy model. The broad inhomogeneous FMR line-width, observation of the Verwey transition, tuning of the <span class="hlt">magnetic</span> domain structure as well as the <span class="hlt">magnetic</span> properties suggest that the NiCoFe2O4 ferrite NPs may be promising for future generation spintronics, magneto-electronics, and ultra-high-density recording media as well as for radar absorbing applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr06791j</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_13 --> <div id="page_14" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="261"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JGRE..11710007M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JGRE..11710007M"><span id="translatedtitle">The history of Mars' dynamo as revealed by modeling <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> near Tyrrhenus Mons and Syrtis Major</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Milbury, C.; Schubert, G.; Raymond, C. A.; Smrekar, S. E.; Langlais, B.</p> <p>2012-10-01</p> <p>The lack of <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> within the major impact basins (Hellas, Argyre, and Isidis) has led many investigators to the conclusion that Mars' dynamo shut down prior to the time when these basins formed (˜4.0 Ga). We test this hypothesis by analyzing gravity and <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> in the regions surrounding Tyrrhenus Mons and Syrtis Major, two volcanoes that were active during the late Noachian and Hesperian. We model <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> that are associated with gravity <span class="hlt">anomalies</span> and generally find that sources located below Noachian surface units tend to favor paleopoles near the equator and sources located below Hesperian surface features favor paleopoles near the geographical poles, suggesting polar wander during the Noachian-Hesperian. Both paleopole clusters have positive and negative polarities, indicating reversals of the field during the Noachian and Hesperian. <span class="hlt">Magnetization</span> of sources below Hesperian surfaces is evidence that the dynamo persisted beyond the formation of the major impact basins. The demagnetization associated with the volcanic construct of Syrtis Major implies dynamo cessation occurred while it was geologically active approximately 3.6 billion years ago. Timing of dynamo activity is fundamentally linked to Mars' climate via the stability of its atmosphere, and is coupled to the extent and duration of surface geologic activity. Thus, the dynamo history is key for understanding both when Mars was most geologically active and when it may have been most hospitable to life.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26880070','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26880070"><span id="translatedtitle">Observation of <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> in one-step solvothermally synthesized nickel-cobalt ferrite nanoparticles.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Datt, Gopal; Sen Bishwas, Mousumi; Manivel Raja, M; Abhyankar, A C</p> <p>2016-02-25</p> <p><span class="hlt">Magnetic</span> <span class="hlt">anomalies</span> corresponding to the Verwey transition and reorientation of anisotropic vacancies are observed at 151 K and 306 K, respectively, in NiCoFe2O4 nanoparticles (NPs) synthesized by a modified-solvothermal method followed by annealing. Cationic disorder and spherical shape induced non-stoichiometry suppress the Verwey transition in the as-synthesized NPs. On the other hand, reorientation of anisotropic vacancies is quite robust. XRD and electron microscopy investigations confirm a single phase spinel structure and the surface morphology of the as-synthesized NPs changes from spherical to octahedral upon annealing. Rietveld analysis reveals that the Ni(2+) ions migrate from tetrahedral (A) to octahedral (B) sites upon annealing. The Mössbauer results show canted spins in both the NPs and the strength of superexchange is stronger in Co-O-Fe than Ni-O-Fe. <span class="hlt">Magnetic</span> force images show that the as-synthesised NPs are single-domain whereas the annealed NPs are multi-domain octahedral particles. The FMR study reveals that both the NPs have a broad FMR line-width; and resonance properties are consistent with the random anisotropy model. The broad inhomogeneous FMR line-width, observation of the Verwey transition, tuning of the <span class="hlt">magnetic</span> domain structure as well as the <span class="hlt">magnetic</span> properties suggest that the NiCoFe2O4 ferrite NPs may be promising for future generation spintronics, magneto-electronics, and ultra-high-density recording media as well as for radar absorbing applications. PMID:26880070</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013PhRvB..88g5109S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013PhRvB..88g5109S"><span id="translatedtitle">NMR investigation of the Knight shift <span class="hlt">anomaly</span> in CeIrIn5 at high <span class="hlt">magnetic</span> fields</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shockley, A. C.; apRoberts-Warren, N.; Nisson, D. M.; Kuhns, P. L.; Reyes, A. P.; Yuan, S.; Curro, N. J.</p> <p>2013-08-01</p> <p>We report nuclear <span class="hlt">magnetic</span> resonance Knight shift data in the heavy-fermion material CeIrIn5 at fields up to 30 T. The Knight shift of the In displays a strong <span class="hlt">anomaly</span>, and we analyze the results using two interpretations. We find that the Kondo lattice coherence temperature and the effective mass of the heavy electrons remain largely unaffected by the <span class="hlt">magnetic</span> field, despite the fact that the Zeeman energy is of the order of the coherence temperature.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMSM51F4330N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMSM51F4330N"><span id="translatedtitle">Evidence for Mini-Magnetospheres at four Lunar <span class="hlt">Magnetic</span> <span class="hlt">Anomalies</span>: Reiner-Gamma, Airy, Descartes and Crozier</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nayak, M.; Garrick-Bethell, I.; Hemingway, D.</p> <p>2014-12-01</p> <p>Lunar swirls are enigmatic high-albedo surface markings co-located with <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>. The existence of mini-magnetospheres has been proposed as a formation mechanism, making small-scale <span class="hlt">magnetic</span> field interactions with the solar wind of interest. Using data from the Lunar Prospector, Clementine, and Advanced Composition Explorer missions, we develop three metrics for the identification of mini-magnetospheres: 1) presence of coherent <span class="hlt">magnetism</span> at low altitude for <span class="hlt">magnetic</span> field measurements taken in the solar wind; 2) directional field distortions that are correlated with changes in incident solar wind azimuth; 3) intensification of total field strength. These metrics are applied to four lunar <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> with various reflectances and <span class="hlt">magnetic</span> field strengths, ranging from fully developed swirls (Reiner-Gamma, Airy) to diffuse albedo patches which may or may not be swirls (Descartes, Crozier). Specifically, we compare <span class="hlt">magnetic</span> field measurements in the solar wind to source <span class="hlt">magnetization</span> models constructed from observations in the lunar wake and Earth's magnetotail. By applying these criteria, we confirm previous findings of magnetosphere-like phenomena at Reiner-Gamma. We also find evidence of these phenomena at Descartes and Airy, and propose that mini-magnetospheres may exist here. At Airy, very large upwind distortions are observed, comparable to the length scale of the <span class="hlt">anomaly</span> itself. At Reiner-Gamma and Descartes, this distortion is significantly smaller, yet the average field strengths are higher, implying that the scale of distortion is linked to the <span class="hlt">anomaly</span>'s field strength. Interestingly, at Crozier, the weakest <span class="hlt">anomaly</span> considered, we do not observe this distortion. However, we do observe evidence of field intensification at high solar wind pressures (16 nPa). While Descartes and Reiner-Gamma are among the strongest <span class="hlt">anomalies</span> on the Moon, and both exhibit magnetospheric properties, only Reiner-Gamma shows a well-developed swirl pattern. Similarly, Airy and Crozier both exhibit properties of magnetospheres, yet only Airy is clearly a swirl. This implies that even if some mini-magnetospheric characteristics are observed, this is not sufficient to create swirl morphology; distribution of the source <span class="hlt">magnetization</span> may play a critical role.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20110013498&hterms=sorting&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dsorting','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20110013498&hterms=sorting&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dsorting"><span id="translatedtitle">Characterization of Lunar Swirls at Mare Ingenii: A Model for Space Weathering at <span class="hlt">Magnetic</span> <span class="hlt">Anomalies</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kramer, Georgianna Y.; Combe, Jean-Philippe; Harnett, Erika M.; Hawke, Bernard Ray; Noble, Sarah K.; Blewett, David T.; McCord, Thomas B.; Giguere, Thomas A.</p> <p>2011-01-01</p> <p>Analysis of spectra from the Clementine ultraviolet-visible and near-infrared cameras of small, immature craters and surface soils both on and adjacent to the lunar swirls at Marc Ingenii has yielded the following conclusions about space weathering at a <span class="hlt">magnetic</span> <span class="hlt">anomaly</span>. (l) Despite having spectral characteristics of immaturity, the lunar swirls arc not freshly exposed surfaces. (2) The swirl surfaces arc regions of retarded weathering, while immediately adjacent regions experience accelerated weathering, (3) Weathering in the off-swirl regions darkens and flattens the spectrum with little to no reddening, which suggests that the production of larger (greater than 40 nm) nanophase iron dominates in these locations as a result of charged particle sorting by the <span class="hlt">magnetic</span> field. Preliminaty analysis of two other lunar swirl regions, Reiner Gamma and Mare Marginis, is consistent with our observations at Mare Ingenii. Our results indicate that sputtering/vapor deposition, implanted solar wind hydrogen, and agglutination share responsibility for creating the range in npFe(sup 0) particle sizes responsible for the spectral effects of space weathering.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011JGRE..116.4008K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011JGRE..116.4008K"><span id="translatedtitle">Characterization of lunar swirls at Mare Ingenii: A model for space weathering at <span class="hlt">magnetic</span> <span class="hlt">anomalies</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kramer, Georgiana Y.; Combe, Jean-Philippe; Harnett, Erika M.; Hawke, Bernard Ray; Noble, Sarah K.; Blewett, David T.; McCord, Thomas B.; Giguere, Thomas A.</p> <p>2011-04-01</p> <p>Analysis of spectra from the Clementine ultraviolet-visible and near-infrared cameras of small, immature craters and surface soils both on and adjacent to the lunar swirls at Mare Ingenii has yielded the following conclusions about space weathering at a <span class="hlt">magnetic</span> <span class="hlt">anomaly</span>. (1) Despite having spectral characteristics of immaturity, the lunar swirls are not freshly exposed surfaces. (2) The swirl surfaces are regions of retarded weathering, while immediately adjacent regions experience accelerated weathering. (3) Weathering in the off-swirl regions darkens and flattens the spectrum with little to no reddening, which suggests that the production of larger (>40 nm) nanophase iron dominates in these locations as a result of charged particle sorting by the <span class="hlt">magnetic</span> field. Preliminary analysis of two other lunar swirl regions, Reiner Gamma and Mare Marginis, is consistent with our observations at Mare Ingenii. Our results indicate that sputtering/vapor deposition, implanted solar wind hydrogen, and agglutination share responsibility for creating the range in npFe0 particle sizes responsible for the spectral effects of space weathering.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19940016195&hterms=chicxulub&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dchicxulub','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19940016195&hterms=chicxulub&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dchicxulub"><span id="translatedtitle">Modelling the gravity and <span class="hlt">magnetic</span> field <span class="hlt">anomalies</span> of the Chicxulub crater</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Aleman, C. Ortiz; Pilkington, M.; Hildebrand, A. R.; Roest, W. R.; Grieve, R. A. F.; Keating, P.</p> <p>1993-01-01</p> <p>The approximately 180-km-diameter Chicxulub crater lies buried by approximately 1 km of sediment on the northwestern corner of the Yucatan Peninsula, Mexico. Geophysical, stratigraphic and petrologic evidence support an impact origin for the structure and biostratigraphy suggests that a K/T age is possible for the impact. The crater's location is in agreement with constraints derived from proximal K/T impact-wave and ejecta deposits and its melt-rock is similar in composition to the K/T tektites. Radiometric dating of the melt rock reveals an age identical to that of the K/T tektites. The impact which produced the Chicxulub crater probably produced the K/T extinctions and understanding the now-buried crater will provide constraints on the impact's lethal effects. The outstanding preservation of the crater, the availability of detailed gravity and <span class="hlt">magnetic</span> data sets, and the two-component target of carbonate/evaporites overlying silicate basement allow application of geophysical modeling techniques to explore the crater under most favorable circumstances. We have found that the main features of the gravity and <span class="hlt">magnetic</span> field <span class="hlt">anomalies</span> may be produced by the crater lithologies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMGP13C..07F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMGP13C..07F"><span id="translatedtitle">Inverse Dipolar <span class="hlt">Magnetic</span> <span class="hlt">Anomaly</span> Over the Volcanic Cone Linked to Reverse Polarity <span class="hlt">Magnetizations</span> in Lavas and Tuffs - Implications for the Conduit System</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fucugauchi, J. U.; Perez-Cruz, L. L.; Trigo-Huesca, A.</p> <p>2012-12-01</p> <p>A combined <span class="hlt">magnetics</span> and paleomagnetic study of Toluquilla monogenetic volcano and associated lavas and tuffs from Valsequillo basin in Central Mexico provides evidence on a <span class="hlt">magnetic</span> link between lavas, ash tuffs and the underground volcanic conduit system. Paleomagnetic analyses show that lavas and ash tuffs carry reverse polarity <span class="hlt">magnetizations</span>, which correlate with the inversely polarized dipolar <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> over the volcano. The <span class="hlt">magnetizations</span> in the lava and tuff show similar southward declinations and upward inclinations, supporting petrological inferences that the tuff was emplaced while still hot and indicating a temporal correlation for lava and tuff emplacement. Conduit geometry is one of the important controlling factors in eruptive dynamics of basaltic volcanoes. However volcanic conduits are often not, or only partly, exposed. Modeling of the dipolar <span class="hlt">anomaly</span> gives a reverse polarity source <span class="hlt">magnetization</span> associated with a vertical prismatic body with southward declination and upward inclination, which correlates with the reverse polarity <span class="hlt">magnetizations</span> in the lava and tuff. The study documents a direct correlation of the paleomagnetic records with the underground magmatic conduit system of the monogenetic volcano. Time scale for cooling of the volcanic plumbing system involves a longer period than the one for the tuff and lava, suggesting that <span class="hlt">magnetization</span> for the source of dipolar <span class="hlt">anomaly</span> may represent a long time average as compared to the spot readings in the lava and tuff. The reverse polarity <span class="hlt">magnetizations</span> in lava and tuff and in the underground source body for the <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> are interpreted in terms of eruptive activity of Toluquilla volcano at about 1.3 Ma during the Matuyama reverse polarity C1r.2r chron.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMSM21B2175D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMSM21B2175D"><span id="translatedtitle">3D Electromagnetic Particle-in-Cell simulations of the solar wind interaction with lunar <span class="hlt">magnetic</span> <span class="hlt">anomalies</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Deca, J.; Lapenta, G.; Divin, A. V.; Lembege, B.; Markidis, S.</p> <p>2013-12-01</p> <p>Unlike the Earth and Mercury, our Moon has no global <span class="hlt">magnetic</span> field and is therefore not shielded from the impinging solar wind by a magnetosphere. However, lunar <span class="hlt">magnetic</span> field measurements made by the Apollo missions provided direct evidence that the Moon has regions of small-scale crustal <span class="hlt">magnetic</span> fields, ranging up to a few 100km in scale size with surface <span class="hlt">magnetic</span> field strengths up to hundreds of nanoTeslas. More recently, the Lunar Prospector spacecraft has provided high-resolution observations allowing to construct <span class="hlt">magnetic</span> field maps of the entire Moon, confirming the earlier results from Apollo, but also showing that the lunar plasma environment is much richer than earlier believed. Typically the small-scale <span class="hlt">magnetic</span> fields are non-dipolar and rather tiny compared to the lunar radius and mainly clustered on the far side of the moon. Using iPic3D we present the first 3D fully kinetic and electromagnetic Particle-in-Cell simulations of the solar wind interaction with lunar <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>. We study the behaviour of a dipole model with variable surface <span class="hlt">magnetic</span> field strength under changing solar wind conditions and confirm that lunar crustal <span class="hlt">magnetic</span> fields may indeed be strong enough to stand off the solar wind and form a mini-magnetosphere, as suggested by MHD and hybrid simulations and spacecraft observations. 3D-PIC simulations reveal to be very helpful to analyze the diversion/braking of the particle flux and the characteristics of the resulting particles accumulation. The particle flux to the surface is significantly reduced at the <span class="hlt">magnetic</span> <span class="hlt">anomaly</span>, surrounded by a region of enhanced density due to the <span class="hlt">magnetic</span> mirror effect. Second, the ability of iPic3D to resolve all plasma components (heavy ions, protons and electrons) allows to discuss in detail the electron physics leading to the highly non-adiabatic interactions expected as well as the implications for solar wind shielding of the lunar surface, depending on the scale size (solar wind protons typically have gyroradii larger than the <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> scale size) and <span class="hlt">magnetic</span> field strength. The research leading to these results has received funding from the European Commission's Seventh Framework Programme (FP7/2007-2013) under the grant agreement SWIFF (project 2633430, swiff.eu). Cut along the dipole axis of the lunar <span class="hlt">anomaly</span>, showing the electron density structure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70028810','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70028810"><span id="translatedtitle">Negative <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> over Mt. Resnik, a subaerially erupted volcanic peak beneath the West Antarctic Ice Sheet</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Behrendt, John C.; Finn, C.; Morse, D.L.; Blankenship, D.D.</p> <p>2006-01-01</p> <p>Mt. Resnik is one of the previously reported 18 subaerially erupted volcanoes (in the West Antarctic rift system), which have high elevation and high bed relief beneath the WAIS in the Central West Antarctica (CWA) aerogeophysical survey. Mt. Resnik lies 300 m below the surface of the West Antarctic Ice Sheet (WAIS); it has 1.6 km topographic relief, and a conical form defined by radar ice-sounding of bed topography. It has an associated complex negative <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> revealed by the CWA survey. We calculated and interpreted <span class="hlt">magnetic</span> models fit to the Mt. Resnik <span class="hlt">anomaly</span> as a volcanic source comprising both reversely and normally <span class="hlt">magnetized</span> (in the present field direction) volcanic flows, 0.5-2.5-km thick, erupted subaerially during a time of <span class="hlt">magnetic</span> field reversal. The Mt. Resnik 305-nT <span class="hlt">anomaly</span> is part of an approximately 50- by 40-km positive <span class="hlt">anomaly</span> complex extending about 30 km to the west of the Mt. Resnik peak, associated with an underlying source complex of about the same area, whose top is at the bed of the WAIS. The bed relief of this shallow source complex has a maximum of only about 400 m, whereas the modeled source is >3 km thick. From the spatial relationship we interpret that this source and Mt Resnik are approximately contemporaneous. Any subglacially (older?) erupted edifices comprising hyaloclastite or other volcanic debris, which formerly overlaid the source to the west, were removed by the moving WAIS into which they were injected as is the general case for the ???1000 volcanic centers at the base of the WAIS. The presence of the <span class="hlt">magnetic</span> field reversal modeled for Mt. Resnik may represent the Bruhnes-Matayama reversal at 780 ka (or an earlier reversal). There are ???100 short-wavelength, steep-gradient, negative <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> observed over the West Antarctic Ice Sheet (WAIS), or about 10% of the approximately 1000 short-wavelength, shallow-source, high-amplitude (50- >1000 nT) "volcanic" <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> in the CWA survey. These negative <span class="hlt">anomalies</span> indicate volcanic activity during a period of <span class="hlt">magnetic</span> reversal and therefore must also be at least 780 ka. The spatial extent and volume of volcanism can now be reassessed for the 1.2 ?? 106 km2 region of the WAIS characterized by <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> defining interpreted volcanic centers associated with the West Antarctic rift system. The CWA covers an area of 3.54 ?? 105 km2; forty-four percent of that area exhibits short-wavelength, high-amplitude <span class="hlt">anomalies</span> indicative of volcanic centers and subvolcanic intrusions. This equates to an area of 0.51 ?? 105 km2 and a volume of 106 km3 beneath the ice-covered West Antarctic rift system, of sufficient extent to be classified as a large igneous province interpreted to be of Oligocene to recent age.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19850044271&hterms=SUSCEPTIBILITY+MAGNETIC&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DSUSCEPTIBILITY%2BMAGNETIC','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19850044271&hterms=SUSCEPTIBILITY+MAGNETIC&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DSUSCEPTIBILITY%2BMAGNETIC"><span id="translatedtitle">Magsat and POGO <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> over the Lord Howe Rise Evidence against a simple continental crustal structure</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Frey, H.</p> <p>1985-01-01</p> <p>Magsat average scalar and POGO reduced-to-pole <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> data both show prominent positive signatures over the Lord Howe Rise. Although generally assumed to be continental in nature, the Lord Howe Rise cannot simply be submerged ordinary continental crust, which would produce a negative <span class="hlt">anomaly</span> contrast with respect to the surrounding higher susceptibility oceanic crust. Three-dimensional modeling of the plateau, using the known crustal structure and assuming an induced origin for the satellite elevation <span class="hlt">anomaly</span>, leads to a model in which the lowest crustal layer in an otherwise 'continental' crustal structure has an unusually high susceptibility in the range cgs 0.008-0.010 (SI 0.10-0.13). Replacement or alteration of the lowest layer by a high-susceptibility rock type may be related to the subsidence of the plateau.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19870053273&hterms=pinto&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dpinto','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19870053273&hterms=pinto&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dpinto"><span id="translatedtitle">Middle atmospheric electrodynamic modification by particle precipitation at the South Atlantic <span class="hlt">magnetic</span> <span class="hlt">anomaly</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gonzalez, W. D.; Dutra, S. L. G.; Pinto, O., Jr.</p> <p>1987-01-01</p> <p>Evidence for a localized middle atmospheric electrodynamic modification at low latitudes (southern Brazilian coast) of the South Atlantic <span class="hlt">Magnetic</span> <span class="hlt">Anomaly</span> (SAMA), in association with enhanced geomagnetic activity, are presented in a unified way combining recent observational efforts and related numerical studies. They involve a distortion effect in the fair weather electric field at balloon altitudes. This effect is attributed to a local intensification of energetic electron precipitation through a related middle atmospheric ionization enhancement and is elucidated by numeric simulation. From the electric field measurements and the numeric simulation, the intensification of precipitation is considered to occur in fairly narrow regions at the observed low L values (around L = 1.13) of the SAMA, with horizontal extensions of the order of a few hundred kilometers. A physical mechanism that could be responsible for this sort of intensification is suggested. Furthermore, a comparison of the phenomenon of middle atmospheric electrodynamic modification at the SAMA with a similar one at auroral latitudes, in response to enhanced solar and geomagnetic activity, is also given.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70030204','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70030204"><span id="translatedtitle">Regional <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>, crustal strength, and the location of the northern Cordilleran fold-and-thrust belt</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Saltus, R.W.; Hudson, T.L.</p> <p>2007-01-01</p> <p>The northern Cordilleran fold-and-thrust belt in Canada and Alaska is at the boundary between the broad continental margin mobile belt and the stable North American craton. The fold-and-thrust belt is marked by several significant changes in geometry: cratonward extensions in the central Yukon Territory and northeastern Alaska are separated by marginward re-entrants. These geometric features of the Cordilleran mobile belt are controlled by relations between lithospheric strength and compressional tectonic forces developed along the continental margin. Regional <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> indicate deep thermal and compositional characteristics that contribute to variations in crustal strength. Our detailed analysis of one such <span class="hlt">anomaly</span>, the North Slope deep <span class="hlt">magnetic</span> high, helps to explain the geometry of the fold-and-thrust front in northern Alaska. This large <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> is inferred to reflect voluminous mafic magmatism in an old (Devonian?) extensional domain. The presence of massive amounts of malic material in the lower crust implies geochemical depletion of the underlying upper mantle, which serves to strengthen the lithosphere against thermal erosion by upper mantle convection. We infer that deep-source <span class="hlt">magnetic</span> highs are an important indicator of strong lower crust and upper mantle. This stronger lithosphere forms buttresses that play an important role in the structural development of the northern Cordilleran fold-and-thrust belt. ?? 2007 The Geological Society of America.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/6465695','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6465695"><span id="translatedtitle">Analysis of the Nuevo Leon <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> and its possible relation to the Cerro Prieto magmatic-hydrothermal system</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Goldstein, N.E.; Wilt, M.J.; Corrigan, D.J.</p> <p>1982-10-01</p> <p>The broad dipolar <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> whose positive peak is centered near Ejido Nuevo Leon, some 5 km east of the Cerro Prieto I Power Plant, has long been suspected to have a genetic relationship to the thermal source of the Cerro Prieto geothermal system. This suspicion was reinforced after several deep geothermal wells, drilled to depths of 3 to 3.5 km over the <span class="hlt">anomaly</span>, intersected an apparent dike-sill complex consisting mainly of diabase but with minor rhyodacite. A detailed fit of the observed <span class="hlt">magnetic</span> field to a computer model indicates that the source may be approximated by a tabular block 4 by 6 km in area, 3.7 km in depth, 2.3 km thick, and dipping slightly to the north. Mafic dike chips from one well, NL-1, were analyzed by means of electron microprobe analyses which showed tham to contain a titanomagnetite that is paramagnetic at in-situ temperature conditions. As the dike mineralogy does not account for the <span class="hlt">magnetic</span> <span class="hlt">anomaly</span>, the <span class="hlt">magnetic</span> source is believed to be a deeper, magnetite-rich assemblage of peridotite-gabbro plutons. the suite of igneous rocks was probably passively emplaced at a shallow depth in response to crustal extension and thinning brought on by strike-slip faulting. The bottom of the <span class="hlt">magnetic</span> source body, at an estimated depth of 6 km, is presumed to be at or near that of the Curie isotherm (575/sup 0/C) for magnetite, the principal ferromagnetic mineral in peridotitic-gabbroic rocks. The geological model derived from the <span class="hlt">magnetic</span> study is generally supported by other geophysical data. In particular, earthquake data suggest dike injection is occurring at depths of 6 to 11 km in an area beneath the <span class="hlt">magnetic</span> source. Thus, it is possible that heat for the geothermal field is being maintained by continuing crustal extension and magmatic activity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6377299','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6377299"><span id="translatedtitle">Analysis of the Nuevo Leon <span class="hlt">Magnetic</span> <span class="hlt">Anomaly</span> and its possible relation to the Cerro Prieto magmatic-hydrothermal system</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Goldstein, N.E.; Corrigan, D.J.; Wilt, M.J.</p> <p>1984-01-01</p> <p>The broad dipolar <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> whose positive peak is centered near Ejido Nuevo Leon, some 5 km east of the Cerro Prieto I power plant, has long been suspected to have a genetic relationship to the thermal source of the Cerro Prieto geothermal system. This suspicion was reinforced after several deep geothermal wells, drilled to depths of 3-3.5 km over the <span class="hlt">anomaly</span>, intersected an apparent dike-sill complex consisting mainly of diabase but with minor rhyodacite. A detailed fit of the observed <span class="hlt">magnetic</span> field to a computer model indicates that the source may be approximated by a tabular block 4 x 6 km in area, 3.7 km in depth, 2.3 km thick, and dipping slightly to the north. Mafic dike chips from one well, NL-1, were analysed by means of electron microprobe analyses which showed them to contain a titanomagnetite that is paramagnetic at in situ temperature conditions. As the dike mineralogy does not account for the <span class="hlt">magnetic</span> <span class="hlt">anomaly</span>, the <span class="hlt">magnetic</span> source is believed to be a deeper, magnetite-rich assemblage of peridotite-gabbro plutons. The suite of igneous rocks was probably emplaced at a shallow depth in response to crustal extension and thinning brought on by en echelon strike-slip faulting. The bottom of the <span class="hlt">magnetic</span> source body, at an estimated depth of 6 km, is presumed to be at or near that of the Curie isotherm (575/sup 0/C) for magnetite, the principal ferromagnetic mineral in peridotiticgabbroic rocks. The geological model derived from the <span class="hlt">magnetic</span> study is generally supported by other geophysical data. In particular, earthquake data suggest dike injection is occurring at depths of 6-11 km in an area beneath the <span class="hlt">magnetic</span> source. Thus, it is possible that heat for the geothermal field is being maintained by continuing crustal extension and magmatic activity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMGP33A3688D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMGP33A3688D"><span id="translatedtitle">Regional gravity and <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> related to a Proterozoic carbonatite terrane in the eastern Mojave Desert, California</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Denton, K. M.; Ponce, D. A.; Miller, D. M.; Jernigan, C. T.</p> <p>2014-12-01</p> <p>One of the world's largest rare earth element carbonatite deposits is located at Mountain Pass in the eastern Mojave Desert, California. The 1.4 Ga carbonatite deposit is hosted by and intruded into 1.7 Ga gneiss and schist that occurs in a narrow north-northwest trending belt along the eastern parts of Clark Mountain Range, Mescal Range, and Ivanpah Mountains. The carbonatite is associated with an ultrapotassic intrusive suite that ranges from shonkinite through syenite and granite. Regional geophysical data reveal that the eastern Mojave carbonatite terrane occurs along the northeast edge of a prominent <span class="hlt">magnetic</span> high and the western margin of a gravity high along the eastern Clark Mountain Range. To improve our understanding of the geophysical and structural framework of the eastern Mojave carbonatite terrane, we collected over 1900 gravity stations and over 600 physical rock property samples to augment existing geophysical data. Carbonatite intrusions typically have distinct gravity, <span class="hlt">magnetic</span>, and radiometric signatures because these deposits are relatively dense, contain magnetite, and are enriched in thorium or uranium. However, our results show that the carbonatite is essentially nonmagnetic with an average susceptibility of 0.18 x 10-3 SI (n=31) and the associated ultrapotassic intrusive suite is very weakly <span class="hlt">magnetic</span> with an average susceptibility of 2.0 x 10-3 SI (n=36). Although the carbonatite body is nonmagnetic, it occurs along a steep gradient of a prominent aeromagnetic <span class="hlt">anomaly</span>. This <span class="hlt">anomaly</span> may reflect moderately <span class="hlt">magnetic</span> mafic intrusive rocks at depth. East of the ultrapotassic intrusive rocks, a prominent north trending <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> occurs in the central part of Ivanpah Valley. Based on geologic mapping in the Ivanpah Mountains, this <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> may reflect Paleoproterozoic mafic intrusive rocks related to the 1.7 Ga Ivanpah Orogeny. Physical property measurements indicate that exposed amphibolite along the eastern Ivanpah Mountains are moderately <span class="hlt">magnetic</span> with an average susceptibility of 26.7 x 10-3 SI (n=15). The north trending gravity <span class="hlt">anomaly</span> along the eastern part of the Clark Mountain Range probably reflects dense gneissic rocks of a similar age, rather than the suite of relatively lower density ultrapotassic intrusive rocks.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012ApPhL.100t2403M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012ApPhL.100t2403M"><span id="translatedtitle"><span class="hlt">Anomalies</span> of <span class="hlt">magnetic</span> properties and magnetovolume effect in Cd1-xMnxGeAs2 at hydrostatic pressure</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mollaev, A. Yu.; Kamilov, I. K.; Arslanov, R. K.; Arslanov, T. R.; Zalibekov, U. Z.; Novotortsev, V. M.; Marenkin, S. F.; Trukhan, V. M.</p> <p>2012-05-01</p> <p>We present the experimental results of the effect hydrostatic pressure up to P ≤ 7 GPa applied at the room temperatures in diluted <span class="hlt">magnetic</span> semiconductor Cd1-xMnxGeAs2 (x = 0.06 - 0.3). We have found the pressure areas at which <span class="hlt">anomalies</span> in <span class="hlt">magnetic</span> properties were observed. Induced by hydrostatic pressure at P > 1.5 GPa <span class="hlt">magnetic</span> phase transitions, interpreted as metamagnetic transition, were observed. The transitions from <span class="hlt">magnetic</span>-ordered into <span class="hlt">magnetic</span> disordered phases in region P > 4.1 GPa on the pressure dependences of relative volume compressibility were detected. We estimated the values of bulk modulus and volume magnetostriction. It is shown that high pressures significantly decrease the Curie temperature with values dTC/dP ≈ (-14.0 ÷ -6.8) K/GPa.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFMNS33B1599P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFMNS33B1599P"><span id="translatedtitle">High-resolution Measurement Of <span class="hlt">Magnetic</span> <span class="hlt">Anomalies</span> With An Unmanned Airship</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Petzke, M.; Hofmeister, P.; Auster, H.; Hoerdt, A.; Glassmeier, K.</p> <p>2011-12-01</p> <p>High-resolution <span class="hlt">magnetic</span> mapping of areas is a suitable way to determine location, geometry and physical parameters of disturbing objects that cause <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>. Areas are often difficult to walk and handheld measurements can become costly. It can also be dangerous to enter areas where ordnance is suspected. In these cases it may be advantageous to use an aircraft to perform the measurement. We use a 6.5 m long unmanned airship. Compared to helicopters or gyrocopters, an advantage is that the damage in case of hazards is almost negligible. We made considerable efforts to construct a system that is easy to control without intense training under moderate wind conditions (up to 2 m/s wind speed). The airship has a mass of 10 kg and is powered by four electric motors with a maximum total power of 4.8 kW. Two of the rotors are used to control the altitude of the ship; the other two can be used to control direction and speed. The required energy is provided by four 4S1P Lithium-Polymer battery packs. Batteries are designed to provide a maximum of 125 A at 14.8 V. They have a capacity of 0.3 kWh and can be recharged in 20 minutes. The airship carries a differential GPS receiver that measures the position of the airship at 100 Hz with a precision of 10 cm. The distance to the ground is measured with ultrasonic sensors. A fluxgate magnetometer measures the <span class="hlt">magnetic</span> field with an accuracy of 1 nT, also at 100 Hz. The flight path does not follow a rigid measuring grid but is a random walk, with roughly constant altitude to achieve a mean sensor position of 2 m above the ground. Thus, near-surface disturbing bodies are well resolved if their distance from each other is greater than 4 m. First measurements demonstrate the feasibility of the system. Future applications will be mid-scale measurements which are too large or too cumbersome for handheld measurements, and too small to justify the use of a manned helicopter.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EP%26S...66...83S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EP%26S...66...83S"><span id="translatedtitle">A revised <span class="hlt">spreading</span> model of the West Philippine Basin</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sasaki, Tomohiro; Yamazaki, Toshitsugu; Ishizuka, Osamu</p> <p>2014-12-01</p> <p>The West Philippine Basin (WPB) occupies the western part of the Philippine Sea (PHS) plate. The WPB is generally considered to have opened from approximately 50 to 30 Ma at the CBF rift; however, the detailed <span class="hlt">spreading</span> history of the WPB is not yet clear. In particular, the origin and age of the southern subbasin, the Palau Basin, are unknown. To better understand the initiation and early evolution of the Izu-Bonin (Ogasawara)-Mariana arc, knowing the configuration of the PHS plate at that time is necessary. In this study, we examine the <span class="hlt">spreading</span> history of the WPB using newly acquired three-component <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> and swath bathymetry data, as well as existing datasets. In the WPB south of the CBF rift, the observed <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> correspond to Chron C16r to C21n (approximately 36 to 46 Ma). Prevailing models of the WPB reconstruction show a decrease in the <span class="hlt">spreading</span> rate from 4.4 to 1.8 cm/year since C18n.2n (approximately 39.5 Ma). Our research, however, indicates that the change in the <span class="hlt">spreading</span> rate is not required to correlate the observed <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> to the geomagnetic polarity reversal timescale. The age of the <span class="hlt">spreading</span> cessation in our interpretation, approximately 36 Ma, is several million years older than in previous estimates, and the <span class="hlt">spreading</span> ceased progressively from southeast to northwest along the CBF rift. In the Palau Basin, seafloor fabrics and <span class="hlt">magnetic</span> lineations trend N-S, which indicates E-W seafloor-<span class="hlt">spreading</span>. Based on 40Ar/39Ar age, we suggest that the <span class="hlt">magnetic</span> lineations correspond to polarity reversals from C18n.1n to C15r (approximately 38.5 to 35 Ma). The <span class="hlt">spreading</span> of the Palau Basin may have been coeval with that of the WPB near the CBF rift, although their <span class="hlt">spreading</span> directions are different.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6135904','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6135904"><span id="translatedtitle">Gravity and <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> associated with Tertiary volcanism and a Proterozoic crustal boundary, Hopi Buttes volcanic field, Navajo Nation (Arizona)</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Donovan-Ealy, P.F. . Geology Dept.); Hendricks, J.D. )</p> <p>1992-01-01</p> <p>The Hopi Buttes volcanic field is located in the Navajo Nation of northeastern Arizona, near the southern margin of the Colorado Plateau. Explosive phreatomagmatic eruptions from late Miocene to mid-Pliocene time produced more than 300 maar-diatremes and deposited limburgite tuffs and tuff breccia and monchiquite dikes, necks and flows within a roughly circular 2,500 km[sup 2] area. The volcanic and volcaniclastic rocks make up the middle member of the Bidahochi Formation, whose lower and upper members are lacustrine and fluvial, respectively. The Bidahochi Formation overlies gently dipping Mesozoic sedimentary rocks exposed in the southwestern portion of the volcanic field. Two significant gravity and <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> appear within the Hopi Buttes volcanic field that are unlike the signatures of other Tertiary volcanic fields on the Colorado Plateau. A circular 20 mGal negative gravity <span class="hlt">anomaly</span> is centered over exposed sedimentary rocks in the southwestern portion of the field. The <span class="hlt">anomaly</span> may be due to the large volume of low density pyroclastic rocks in the volcanic field and/or extensive brecciation of the underlying strata from the violent maar eruptions. The second significant <span class="hlt">anomaly</span> is the northeast-trending Holbrook lineament, a 5 km-wide gravity and <span class="hlt">magnetic</span> lineament that crosses the southeastern part of the volcanic field. The lineament reflects substantial gravity and <span class="hlt">magnetic</span> decreases of 1.67 mGals/km and 100 gammas/km respectively, to the southeast. Preliminary two-dimensional gravity and <span class="hlt">magnetic</span> modeling suggests the lineament represents a major Proterozoic crustal boundary and may correlate with one of several Proterozoic faults exposed in the transition zone of central Arizona. Gravity modeling shows a 3--5 km step'' in the Moho near the crustal boundary. The decrease in depth of the Moho to the northwest indicates either movement along the fault or magmatic upwelling beneath the volcanic field.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_14 --> <div id="page_15" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="281"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002EP%26S...54..907N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002EP%26S...54..907N"><span id="translatedtitle">Unusual ionospheric absorption characterizing energetic electron precipitation into the South Atlantic <span class="hlt">Magnetic</span> <span class="hlt">Anomaly</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nishino, M.; Makita, K.; Yumoto, K.; Rodrigues, F. S.; Schuch, N. J.; Abdu, M. A.</p> <p>2002-09-01</p> <p>An imaging riometer (IRIS) was installed newly in the southern area of Brazil in order to investigate precipitation of energetic electrons into the South Atlantic <span class="hlt">Magnetic</span> <span class="hlt">Anomaly</span> (SAMA). An unusual ionospheric absorption event was observed in the nighttime (~20 h LT) near the maximum depression (Dst ~ -164 nT) and the following positive excursion during the strong geomagnetic storm on September 22-23, 1999. The unusual absorption that has short time-duration of 30-40 min shows two characteristic features: One feature is a sheet structure of the absorption appearing at the high-latitude part of the IRIS field-of-view, showing an eastward drift from the western to the eastern parts and subsequent retreat to the western part. Another feature is a meridionally elongated structure with a narrow longitudinal width (100-150 km) appearing from the zenith to the low-latitude part of the IRIS field-of-view, enhanced simultaneously with the sheet absorption, and is subsequently changed to a localized structure. These features likely characterize precipitation of energetic electrons into the SAMA ionosphere, associated with substorm occurrences during the strong geomagnetic storm. From the eastward drift (~250 m/s) of the sheet absorption, precipitating electrons are estimated to be ~20 keV energies, assuming plasmaspheric electric fields of 1.8 mV/m. However, no ionospheric effect due to the precipitating electrons was definitely detected by the ionosonde measurements at Cachoeira Paulista, separated eastward by about 1000 km from the IRIS station.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2269513','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2269513"><span id="translatedtitle">Cortical <span class="hlt">spreading</span> depression in the gyrencephalic feline brain studied by <span class="hlt">magnetic</span> resonance imaging</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>James, Michael F; Smith, Martin I; Bockhorst, Kurt H J; Hall, Laurance D; Houston, Gavin C; Papadakis, Nikolaos G; Smith, Justin M; Williams, Emma J; Xing, Da; Parsons, Andrew A; Huang, Christopher L-H; Carpenter, T Adrian</p> <p>1999-01-01</p> <p>Time-lapse diffusion-weighted <span class="hlt">magnetic</span> resonance imaging (DWI) was used to detect and characterize complex waves of cortical <span class="hlt">spreading</span> depression (CSD) evoked with KCl placed upon the suprasylvian gyrus of anaesthetized cats. The time-lapse representations successfully demonstrated primary CSD waves that propagated with elliptical wavefronts selectively over the ipsilateral cerebral hemispheres with a velocity of 3.8 ± 0.70 mm min−1 (mean ± s.e.m. of 5 experiments). In contrast, the succeeding secondary waves often remained within the originating gyrus, were slower (velocity 2.0 ± 0.18 mm min−1), more fragmented and varied in number. Computed traces of the apparent diffusion coefficients (ADCs) showed negative deflections followed by monotonic decays (amplitudes: primary wave, -19.9 ± 2.8 %; subsequent waves, -13.6 ± 1.9 %; duration at half-maximal decay, 150-200 s) when determined from regions of interest (ROIs) through which both primary and succeeding CSD waves propagated. The passage of both the primary and the succeeding waves often correlated with transient DC potential deflections recorded from the suprasylvian gyrus. The detailed waveforms of the ADC and the T2*-weighted (blood oxygenation level-dependent: BOLD) traces showed a clear reciprocal correlation. These imaging features that reflect disturbances in cellular water balance agree closely with BOLD measurements that followed the propagation velocities of the first and subsequent CSD events. They also provide a close physiological correlate for clinical observations of cortical blood flow disturbances associated with human migraine. PMID:10577057</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20120011638&hterms=simplex&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dsimplex','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20120011638&hterms=simplex&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dsimplex"><span id="translatedtitle">Interpretation of the Total <span class="hlt">Magnetic</span> Field <span class="hlt">Anomalies</span> Measured by the CHAMP Satellite Over a Part of Europe and the Pannonian Basin</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kis, K. I.; Taylor, Patrick T.; Wittmann, G.; Toronyi, B.; Puszta, S.</p> <p>2012-01-01</p> <p>In this study we interpret the <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> at satellite altitude over a part of Europe and the Pannonian Basin. These <span class="hlt">anomalies</span> are derived from the total <span class="hlt">magnetic</span> measurements from the CHAMP satellite. The <span class="hlt">anomalies</span> reduced to an elevation of 324 km. An inversion method is used to interpret the total <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> over the Pannonian Basin. A three dimensional triangular model is used in the inversion. Two parameter distributions: Laplacian and Gaussian are investigated. The regularized inversion is numerically calculated with the Simplex and Simulated Annealing methods and the anomalous source is located in the upper crust. A probable source of the <span class="hlt">magnetization</span> is due to the exsolution of the hematite-ilmenite minerals.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1999JGR...10429175M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1999JGR...10429175M"><span id="translatedtitle">Three-dimensional Euler deconvolution and tectonic interpretation of marine <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> data in the Puerto Rico Trench</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Muszala, S. P.; Grindlay, N. R.; Bird, R. T.</p> <p>1999-12-01</p> <p>During the summer of 1996 single-channel-seismic, <span class="hlt">magnetic</span>, gravity, Hydrosweep bathymetric and HMR1 sidescan data were collected north of the island of Puerto Rico to constrain the geologic and tectonic setting of the Puerto Rico trench. <span class="hlt">Magnetic</span> data from this cruise are merged with other available data, then processed and interpreted with the aid of the Euler deconvolution method. The area north of the island of Puerto Rico is divided into three <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> zones. Zone 1 is dominated by northwest to southeast trending <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>. Zone 2 consists of an east-west region of relatively low amplitude <span class="hlt">anomalies</span> and occurs south of zone 1. Zone 3 is dominated by the highest <span class="hlt">magnetic</span> values in the study area and the source region is roughly centered under the island of Puerto Rico. Respectively, these zones approximate three geologic provinces of the Puerto Rico trench composed of Early Cretaceous ocean crust with sedimentary cover, a blueschist belt and an Oligocene-Cretaceous island arc with a limestone cap. Also mapped are the Main Ridge fracture zone and the Fourth of July fracture zone, both on the North American plate, which correlate with the Main Ridge and Fourth of July Ridge on the Caribbean plate. The 3-D Euler deconvolution facilitates the identification of new faults as well as the mapping of known faults also evident in the seismic and bathymetric data. A model concerning the formation of the Puerto Rico trench is proposed that incorporates the existence of strike-slip faults and the fracture zones associated with the subduction of the North America Plate. Evidence from this study support a tectonic interpretation of subduction followed by more recent strike-slip faulting that is accompanied by only a minimal amount of subduction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70036631','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70036631"><span id="translatedtitle">Airborne gamma-ray and <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> signatures of serpentinite in relation to soil geochemistry, northern California</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>McCafferty, A.E.; Van Gosen, B. S.</p> <p>2009-01-01</p> <p>Serpentinized ultramafic rocks and associated soils in northern California are characterized by high concentrations of Cr and Ni, low levels of radioelements (K, Th, and U) and high amounts of ferrimagnetic minerals (primarily magnetite). Geophysical attributes over ultramafic rocks, which include airborne gamma-ray and <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> data, are quantified and provide indirect measurements on the relative abundance of radioelements and <span class="hlt">magnetic</span> minerals, respectively. Attributes are defined through a statistical modeling approach and the results are portrayed as probabilities in chart and map form. Two predictive models are presented, including one derived from the aeromagnetic <span class="hlt">anomaly</span> data and one from a combination of the airborne K, Th and U gamma-ray data. Both models distinguish preferential values within the aerogeophysical data that coincide with mapped and potentially unmapped ultramafic rocks. The <span class="hlt">magnetic</span> predictive model shows positive probabilities associated with <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> highs and, to a lesser degree, <span class="hlt">anomaly</span> lows, which accurately locate many known ultramafic outcrops, but more interestingly, locate potentially unmapped ultramafic rocks, possible extensions of ultramafic bodies that dip into the shallow subsurface, as well as prospective buried ultramafic rocks. The airborne radiometric model shows positive probabilities in association with anomalously low gamma radiation measurements over ultramafic rock, which is similar to that produced by gabbro, metavolcanic rock, and water bodies. All of these features share the characteristic of being depleted in K, Th and U. Gabbro is the only rock type in the study area that shares similar <span class="hlt">magnetic</span> properties with the ultramafic rock. The aerogeophysical model results are compared to the distribution of ultramafic outcrops and to Cr, Ni, K, Th and U concentrations and <span class="hlt">magnetic</span> susceptibility measurements from soil samples. Analysis of the soil data indicates high positive correlation between <span class="hlt">magnetic</span> susceptibilities and concentration of Cr and Ni. Although the study focused on characterizing the geophysical properties of ultramafic rocks and associated soils, it has also yielded information on other rock types in addition to ultramafic rocks, which can also locally host naturally-occurring asbestos; specifically, gabbro and metavolcanic rocks.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/836904','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/836904"><span id="translatedtitle"><span class="hlt">ANOMALIES</span> IN THE APPLIED <span class="hlt">MAGNETIC</span> FIELDS ON DIII-D AND THEIR IMPLICATIONS FOR THE UNDERSTANDING OF STABILITY EXPERIMENTS</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>LUXON,J.L; SCHAFFER,M.J; JACKSON,G.L; LEUER,J.A; NAGY,A; SCOVILLE,J.T; STRAIT,E.J</p> <p>2003-02-01</p> <p>Small non-axisymmetric <span class="hlt">magnetic</span> fields are known to cause serious loss of stability in tokamaks leading to loss of confinement and abrupt termination of plasma current (disruptions). The best known examples are the locked mode and the resistive wall mode. Understanding of the underlying field <span class="hlt">anomalies</span> (departures in the hardware-related fields from ideal toroidal and poloidal fields on a single axis) and the interaction of the plasma with them is crucial to tokamak development. Results of both locked mode experiments and resistive wall mode experiments done in DIII-D tokamak plasmas have been interpreted to indicate the presence of a significant anomalous field. New measurements of the <span class="hlt">magnetic</span> field <span class="hlt">anomalies</span> of the hardware systems have been made on DIII-D. The measured field <span class="hlt">anomalies</span> due to the plasma shaping coils in DIII-D are smaller than previously reported. Additional evaluations of systematic errors have been made. New measurements of the anomalous fields of the ohmic heating and toroidal coils have been added. Such detailed in situ measurements of the fields of a tokamak are unique. The anomalous fields from all of the coils are one third of the values indicated from the stability experiments. These results indicate limitations in the understanding of the interaction of the plasma with the external field. They indicate that it may not be possible to deduce the anomalous fields in a tokamak from plasma experiments and that we may not have the basis needed to project the error field requirements of future tokamaks.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19740020167&hterms=Kosmos&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DKosmos','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19740020167&hterms=Kosmos&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DKosmos"><span id="translatedtitle">Analysis of the nature of excessive cosmic radiation in the area of the Brazilian <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> at altitudes 250-500km, from Kosmos-225 satellite data</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Raychenko, L. V.</p> <p>1974-01-01</p> <p>Results are presented from a study of the region of anomalous cosmic radiation in the area of the Brazilian <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> at the altitudes 250-500 km, using data measurements taken on the Kosmos-225 satellite (14-29 June 1968). The existence of a stable intensity <span class="hlt">anomaly</span> discovered in the experiments on the second and third Soviet spacecraft-satellites is confirmed. The total vector of the geomagnetic field at different altitudes was compared with isoline maps. An altitude profile of the South Atlantic <span class="hlt">anomaly</span> of radiation intensity was obtained, using data from the same instrument. The nature of the <span class="hlt">anomalies</span> in cosmic radiation intensity over the regions of negative <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> is discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16..161D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16..161D"><span id="translatedtitle">Electromagnetic particle-in-cell simulations of the solar wind interaction with lunar <span class="hlt">magnetic</span> <span class="hlt">anomalies</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Deca, Jan; Divin, Andrey; Lapenta, Giovanni; Lembège, Bertrand; Markidis, Stefano; Horányi, Mihály</p> <p>2014-05-01</p> <p>We present the first three-dimensional fully kinetic and electromagnetic simulations of the solar wind interaction with lunar crustal <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> (LMAs). Using the implicit particle-in-cell code iPic3D, we confirm that LMAs may indeed be strong enough to stand off the solar wind from directly impacting the lunar surface forming a mini-magnetosphere, as suggested by spacecraft observations and theory. In contrast to earlier MHD and hybrid simulations, the fully kinetic nature of iPic3D allows to investigate the space charge effects and in particular the electron dynamics dominating the near-surface lunar plasma environment. We describe the general picture of the interaction of a dipole model centred just below the lunar surface under various solar wind and plasma conditions and focus on the kinetic effects. It is shown that the configuration is dominated by electron motion, because the LMA scale size is small with respect to the gyroradius of the solar wind ions. Driven by strong pressure anisotropies, the mini-magnetosphere is also unstable over time, leading to only temporal shielding of the surface underneath. Our work opens new frontiers of research toward a deeper understanding of LMAs and is ideally suited to be compared with field or particle observations from spacecraft such as Kaguya (SELENE), Lunar Prospector or ARTEMIS. The ability to evaluate the implications for future lunar exploration as well as lunar science in general hinges on a better understanding of LMAs. This research has received funding from the European Commission's FP7 Program with the grant agreement SWIFF (project 2633430, swiff.eu) and EHEROES (project 284461, www.eheroes.eu). The simulations were conducted on the computational resources provided by the PRACE Tier-0 project 2011050747 (Curie supercomputer). This research was supported by the Swedish National Space Board, Grant No. 136/11. JD has received support through the HPC-Europa2 visitor programme (project HPC08SSG85) and the KuLeuven Junior Mobility Programme Special Research Fund.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19910025695&hterms=slip+fault&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dslip%2Bfault','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19910025695&hterms=slip+fault&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dslip%2Bfault"><span id="translatedtitle">Pacific-North American plate motion from very long baseline interferometry compared with motion inferred from <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>, transform faults, and earthquake slip vectors</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Argus, Donald F.; Gordon, Richard G.</p> <p>1990-01-01</p> <p>Geodetic VLBI measurements were used to test whether the Pacific-North American plate velocity averaged over several years of direct observation (1984-1987) equals that averaged over millions of years. It was also tested whether this velocity parallels the San Andreas fault, transform faults and earthquake slip vectors in the Gulf of California, and earthquake slip vectors along the Queen Charlotte fault, along the Alaskan peninsula, and along the Kamchatkan peninsula. The VLBI data provide an estimate of the direction of plate motion that is independent of estimates from fault azimuths and earthquake slip vectors. The Euler vector determined from VLBI was found to be nearly identical to the Euler vector of plate motion model NUVEL-1, which is based on the trends of transform faults, earthquake slip vectors, and <span class="hlt">spreading</span> rates from marine <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> that average motion since 3 Ma. The velocity between the Pacific and North American plates averaged over the past several years equals or nearly equals its velocity averaged over the past several million years, the difference along their boundary nowhere exceeding 4 + or - 7 mm/yr.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JGRB..118.5147H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JGRB..118.5147H"><span id="translatedtitle">Deep-sea <span class="hlt">magnetic</span> vector <span class="hlt">anomalies</span> over the Hakurei hydrothermal field and the Bayonnaise knoll caldera, Izu-Ogasawara arc, Japan</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Honsho, Chie; Ura, Tamaki; Kim, Kangsoo</p> <p>2013-10-01</p> <p>We conducted deep-sea <span class="hlt">magnetic</span> measurements using autonomous underwater vehicles in the Bayonnaise knoll caldera, the Izu-Ogasawara island arc, which hosts the large Hakurei hydrothermal field. We improved the conventional correction method applied for removing the effect of vehicle <span class="hlt">magnetization</span>, thus greatly enhancing the precision of the resulting vector <span class="hlt">anomalies</span>. The <span class="hlt">magnetization</span> distribution obtained from the vector <span class="hlt">anomaly</span> data shows a 2 km wide belt of high <span class="hlt">magnetization</span>, trending NNW-SSE going through the caldera, and a low-<span class="hlt">magnetization</span> zone 300 m by 500 m in area, extending over the Hakurei site. Comparison between the results obtained using the vector <span class="hlt">anomaly</span> and the total intensity <span class="hlt">anomaly</span> shows that the <span class="hlt">magnetic</span> field is determined more accurately, especially in areas of sparse data distribution, when the vector <span class="hlt">anomaly</span> rather than the total intensity <span class="hlt">anomaly</span> is used. We suggest a geologically motivated model that basaltic volcanism associated with the back-arc rifting occurred after the formation of the caldera, resulting in the formation of the high-<span class="hlt">magnetization</span> belt underneath the silicic caldera. The Hakurei hydrothermal field lies in the intersection of the basaltic volcanism belt and the caldera wall fault, suggesting a mechanism that hot water generated by the heat of the volcanic activity has been spouting out through the caldera wall fault. The deposit apparently extends beyond the low-<span class="hlt">magnetization</span> zone, climbing up the caldera wall. This may indicate that hot water rising from the deep through the alteration zone is transported laterally when it comes near the seafloor along fissures and fractures in the caldera wall.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19840012878','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19840012878"><span id="translatedtitle">Petrologic and geophysical study of the source of long wavelength crustal <span class="hlt">magnetic</span> <span class="hlt">anomalies</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Marsch, B.; Schlinger, C. M.</p> <p>1983-01-01</p> <p>The <span class="hlt">magnetic</span> mineralogy and <span class="hlt">magnetic</span> signature of banded ion formations, diagenetic (unmetamorphosed) and low grade banded iron formations, high-grade mineralogy, and phase equilibria of magnetite inorogenic magmers are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFMGP42A..02H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFMGP42A..02H"><span id="translatedtitle">Rock <span class="hlt">magnetic</span> characteristics of faulted sediments with <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>: A case study from the Albuquerque Basin, Rio Grande Rift, New Mexico (Invited)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hudson, M. R.; Grauch, V. J.</p> <p>2009-12-01</p> <p>High-resolution airborne surveys in the Rio Grande rift have documented abundant short-wavelength, low-amplitude <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> generated at faults within basin sediments. We present a rock <span class="hlt">magnetic</span> study bearing on the source of a10-20-nT linear <span class="hlt">anomaly</span> over the San Ysidro normal fault, which is well exposed in outcrop in the northern part of the Albuquerque Basin. <span class="hlt">Magnetic</span> susceptibility (MS) values (SI vol) from 310 sites distributed through a 1200-m-thick composite section of rift-filling sediments of Santa Fe Group and pre-rift sedimentary rocks juxtaposed by the San Ysidro fault have lognormal distributions with well-defined means. These averages generally increase up section through eight map units: from 1.7E-4 to 2.2E-4 in the pre-rift Cretaceous and Eocene rocks, from 9.9E-4 to 1.2E-3 in three units of the Miocene Zia and Cerro Conejo Formations of the Santa Fe Group, and from 1.5E-3 to 3.5E-3 in three units of the Miocene-Pliocene Arroyo Ojito and Ceja Formations of the Santa Fe Group. Remanent <span class="hlt">magnetization</span> is not important; Koenigsberger ratios are less than 0.3 for Santa Fe Group samples. Rock <span class="hlt">magnetic</span> parameters (e.g., ARM/MS and S ratios) and petrography indicate that detrital magnetite content and its variable oxidation to maghemite and hematite are the predominant controls of <span class="hlt">magnetic</span> property variations within the Santa Fe Group sediments. Magnetite is present in rounded detrital grains (including both homogeneous and subdivided types) and as fine inclusions in volcanic rock fragments. Santa Fe Group sediments with highest <span class="hlt">magnetic</span> susceptibility have greatest <span class="hlt">magnetic</span>-grain size as indicated by lowest ARM/MS ratios. <span class="hlt">Magnetic</span> susceptibility increases progressively with sediment grain size to pebbly sand within the fluvial Arroyo Ojito Formation. In contrast, MS reaches highest values in fine to medium sands in eolian Zia Formation. Partial oxidation of detrital magnetite and resultant lower MS is spatially associated with calcite cementation in the Santa Fe Group; both oxidation and cementation probably reflect past flow of ground water through permeable horizons. <span class="hlt">Magnetic</span> models of geologic cross sections that incorporate mean MS for the different stratigraphic units successfully mimic the aeromagnetic profiles across the San Ysidro fault. These models demonstrate multiple levels of <span class="hlt">magnetic</span> contrasts due to fault juxtaposition of stratigraphic units, with contributions to the <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> that vary along strike due to uneven erosion and dip of strata. Sediment provenance, depositional facies, and post-depositional preservation and alteration of <span class="hlt">magnetic</span> minerals are all factors that contribute to producing aeromagnetic <span class="hlt">anomalies</span> in faulted basin sediments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMGP23A3659M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMGP23A3659M"><span id="translatedtitle">Additions to <span class="hlt">Magnetic</span> Trackline Archive For Improvements to Earth <span class="hlt">Magnetic</span> <span class="hlt">Anomaly</span> Grid (EMAG2) and Improvements to Data Dissemination at NGDC</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Meyer, B.; Jencks, J.; Barckhausen, U.; Ishihara, T.; Campagnoli, J.</p> <p>2014-12-01</p> <p>The National Geophysical Data Center (NGDC) is the primary archive of marine geophysical data worldwide. However, it has been challenging for scientist to discover and access data due to variable data formats, non-digital data holdings, and transitioning data discovery portals. In 2014, NGDC made a concerted effort to identify, ingest, and archive all publicly available <span class="hlt">magnetic</span> trackline data for access via a new Trackline Geophysical Data web-based interface. Non-digital data were digitized and added to the Global Geophysical Database and are now available for download in a common MGD77 format. All ancillary and analog data are accessible via the same interface, without having to navigate through multiple directories or prompts. The result is over 16.5 million miles of <span class="hlt">magnetic</span> trackline data are now available, both through NGDC's improved user interface and as a web service for incorporation into other portals. This allows the geoscience community unprecedented access to global geophysical <span class="hlt">magnetic</span> trackline data from a secure long-term archive. The addition of 6.5 million miles of <span class="hlt">magnetic</span> trackline data to the database, since the previous release of the Earth <span class="hlt">Magnetic</span> <span class="hlt">Anomaly</span> Grid (EMAG2), will give NGDC the ability to improve the model coverage, especially in areas of low coverage, such as around the Eltanin Fracture Zone in the South Pacific. This poster will focus on some key data additions and how they will help us validate the accuracy of the ocean age model/directional gridding algorithm and improve the Earth <span class="hlt">Magnetic</span> <span class="hlt">Anomaly</span> Grid going forward.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004AGUSMGP31A..15G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004AGUSMGP31A..15G"><span id="translatedtitle">Lineated Near Bottom <span class="hlt">Magnetic</span> <span class="hlt">Anomalies</span> Over an Oceanic Core Complex, Atlantis Massif (Mid-Atlantic Ridge at 30°N)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gee, J.; Blackman, D.</p> <p>2004-05-01</p> <p>Despite significant effort during the four decades since the Vine-Matthews-Morley hypothesis was first advanced, the relative importance of lower crustal (and possibly upper mantle) sources in generating lineated marine <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> remains uncertain. Remanence measurements from samples obtained by drilling or dredging provide the most direct evidence that these deeper layers can be significant <span class="hlt">anomaly</span> sources. Near bottom <span class="hlt">anomaly</span> measurements over tectonic exposures of the lower crust/upper mantle can yield valuable complementary information (e.g., patterns of polarity boundaries) as well as provide constraints on the timing and uplift history of these exposures. Here we report results from a near bottom <span class="hlt">magnetic</span> survey of the Atlantis Massif, an oceanic core complex that formed within the past 1.5-2 Myr at the intersection of the Mid-Atlantic Ridge (30°N) and the Atlantis transform fault. Geological and geophysical data indicate the presence of gabbro and peridotite over much of the corrugated central dome, inferred to be the footwall of a detachment fault. A vector magnetometer deployed 25m aft of the deeply towed side scan sonar system allowed measurement of both the total field and horizontal and vertical anomalous fields. Five profiles across the central dome reveal a lineated <span class="hlt">anomaly</span> low that was not evident in earlier sea surface profiles. The presence of lineated <span class="hlt">anomalies</span> over presumed gabbro and ultramafic exposures may record the acquisition of remanence as these rocks were exhumed by detachment faulting. <span class="hlt">Anomaly</span> profiles over the Lost City hydrothermal vent field exhibit a pronounced <span class="hlt">magnetic</span> low (reversed polarity), suggesting that active serpentinization is not responsible for the overall <span class="hlt">magnetization</span> pattern. When combined with results from planned IODP drilling at the site, these data should provide significant insights into the importance of gabbro and peridotite lithologies as sources for lineated <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EP%26S...66...68S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EP%26S...66...68S"><span id="translatedtitle">Detailed bathymetry and <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> in the Central Ryukyu Arc, Japan: implications for a westward shift of the volcanic front after approximately 2.1 Ma</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sato, Taichi; Oda, Hirokuni; Ishizuka, Osamu; Arai, Kohsaku</p> <p>2014-12-01</p> <p>Detailed bathymetry and <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> in the southern part of the Central Ryukyu Arc reveal recent volcanic structures in a southwestward extension of the active volcanic front of the Ryukyu Arc. A line of bathymetric highs running subparallel to this recent volcanic front was observed approximately 20 km to the east. A set of small, sharply defined <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> extends southward from this line of bathymetric highs to the islands Kume-jima and Aguni-jima, suggesting the former existence of an ancient volcanic front. The ages of volcanic rocks from these islands indicate that magmatic activity along the ancient volcanic front continued until at least approximately 2.1 Ma. The presence of <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> between the two volcanic fronts suggests that the volcanic front has moved gradually westward. This shift can be explained by the termination of asthenospheric upwelling and/or the rapid retreat of the Ryukyu Trench after its change in subduction direction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.T53B4687S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.T53B4687S"><span id="translatedtitle">Detailed bathymetry and <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> inthe Central Ryukyu Arc, Japan: implications for a westward shift of the volcanic front after ~2.1 Ma</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sato, T.; Oda, H.; Ishizuka, O.; Arai, K.</p> <p>2014-12-01</p> <p>Detailed bathymetry and <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> in the southern part of the Central Ryukyu Arc reveal recent volcanic structures in a southwestward extension of the active volcanic front of the Ryukyu Arc. A line of bathymetric highs running subparallel to this recent volcanic front was observed ~20 km to the east. A set of small, sharply defined <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> extends southward from this line of bathymetric highs to the islands Kume-jima and Aguni-jima, suggesting the former existence of an ancient volcanic front. The ages of volcanic rocks from these islands indicate that magmatic activity along the ancient volcanic front continued until at least ~2.1 Ma. The presence of <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> between the two volcanic fronts suggests that the volcanic front has moved gradually westward. This shift can be explained by the termination of asthenospheric upwelling and/or the rapid retreat of the Ryukyu Trench after its change in subduction direction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22216062','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22216062"><span id="translatedtitle">An annular high-current electron beam with an energy <span class="hlt">spread</span> in a coaxial <span class="hlt">magnetically</span> insulated diode</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Grishkov, A. A. Pegel, I. V.</p> <p>2013-11-15</p> <p>An elementary theory of an annular high-current electron beam in a uniform transport channel and a coaxial <span class="hlt">magnetically</span> insulated diode is generalized to the case of counterpropagating electron beams with a <span class="hlt">spread</span> over kinetic energies. Expressions for the sum of the absolute values of the forward and backward currents in a uniform transport channel and for the flux of the longitudinal component of the generalized momentum in a coaxial <span class="hlt">magnetically</span> insulated diode as functions of the maximum electron kinetic energy are derived for different values of the relative width of the energy distribution function. It is shown that, in a diode with an expanding transport channel and a virtual cathode limiting the extracted current, counterpropagating particle flows are established between the cathode and the virtual cathode within a certain time interval after the beginning of electron emission. The accumulation of electrons in these flows is accompanied by an increase in their <span class="hlt">spread</span> over kinetic energies and the simultaneous decrease in the maximum kinetic energy. The developed model agrees with the results of particle-in-cell simulations performed using the KARAT and OOPIC-Pro codes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013PlPhR..39..936G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013PlPhR..39..936G"><span id="translatedtitle">An annular high-current electron beam with an energy <span class="hlt">spread</span> in a coaxial <span class="hlt">magnetically</span> insulated diode</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Grishkov, A. A.; Pegel, I. V.</p> <p>2013-11-01</p> <p>An elementary theory of an annular high-current electron beam in a uniform transport channel and a coaxial <span class="hlt">magnetically</span> insulated diode is generalized to the case of counterpropagating electron beams with a <span class="hlt">spread</span> over kinetic energies. Expressions for the sum of the absolute values of the forward and backward currents in a uniform transport channel and for the flux of the longitudinal component of the generalized momentum in a coaxial <span class="hlt">magnetically</span> insulated diode as functions of the maximum electron kinetic energy are derived for different values of the relative width of the energy distribution function. It is shown that, in a diode with an expanding transport channel and a virtual cathode limiting the extracted current, counterpropagating particle flows are established between the cathode and the virtual cathode within a certain time interval after the beginning of electron emission. The accumulation of electrons in these flows is accompanied by an increase in their <span class="hlt">spread</span> over kinetic energies and the simultaneous decrease in the maximum kinetic energy. The developed model agrees with the results of particle-in-cell simulations performed using the KARAT and OOPIC-Pro codes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003EAEJA....14272S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003EAEJA....14272S"><span id="translatedtitle">Phase equilibria at alkali-rich early proterozoic banded iron formation, Kursk <span class="hlt">magnetic</span> <span class="hlt">anomaly</span>, Russia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sayko, K. A.; Gerasimov, V. Yu.; Poskryakova, M. V.</p> <p>2003-04-01</p> <p>Banded iron formation (BIF) rocks of Kursk <span class="hlt">Magnetic</span> <span class="hlt">anomaly</span> (KMA) are distinguished from well known Precambrian BIF by the alkali enrichment and aluminum depletion and as a total absence of the aluminum bearing minerals. From layered silicates the maximum saturated potassium phases seladonite and tetraferribiotite are of widespread occurrence instead stilpnomelane, minnesotaite and greenalite commonplace for low grade BIF. It has been widely distribution of the seladonite with the assemblage of tetraferribiotite, magnetite, hematite, and quartz distinguish ferruginous quartzites Mikhailovsk iron deposit (KMA) from well known Precambrian BIF of the ancient shields. From Fe-Mg silicates the aegirine, ribeckite and aluminum-less chlorite are present. The hematite and magnetite stability in the ferruginous quartzites assemblages suggest the high values of the oxygen fugacity near magnetite-hematite buffer. This is confirmed by somewhat increasing XMg values for seladonite, tetraferribiotite, chlorite, and ribeckite. The minerals producing with large amounts of ferric iron (seladonite, tetraferribiotite) in the ferruginous quartzites of Mikhailovsk iron deposit is caused by the oxygen fugacity high values. For example the ferrichamosite (Fe_5Fe3+(Fe3+Si_3)O10(OH)_8) is produced in place of the commonplace for the low-grade BIF greenalite (Fe_6Si_4O10(OH)_8). As a whole chlorites are a rarity in BIFs (Laird, 1989) through low rocks aluminum content and represent by chamosite (Gole, 1981), clinochlore and ripidolite (Miyano, Beukes, 1997). Chlorite in studied ferruginous quartzites has a uncommon aluminumless composition with high Fe3+ content and corresponds hypothetical end-member of chamosite - "ferrichamosite" and "ferriclinochlore" - "ferrichamosite" series (Burt, 1989). Uncommon aluminumless chlorite composition assumes that it appears during low-grade metamorphism and possible catagenesis: Mag + Hem + Qtz rightarrow H_2O rightarrow Fe-Chm + O_2 Sid + Qtz + Mag + Hem + H_2O rightarrow Fe-Chm + CO_2 + O_2. The seladonite producing is caused by relationship of the enriched K^+ metamorphic fluid with the BIF rocks: Sid + Qtz + Mag + Hem + H_2O + ^+ rightarrow Sld + CO_2 + O_2. It seems likely that tetraferribiotite produced similar to ferroseladonite: Mag + Sid + Qtz + H_2O + ^+ rightarrow Fe-Ann + CO_2 + O_2. The chlorite and potassium micas producing through siderite decomposition is more realistic because they content detectable magnesium. The sequence of mineral assemblages change is observed for alkali-rich iron quartzites with increasing temperature and/or oxygen fugacity. Reaction structures suggest ferriannite producing as a result following reactions: (1) through partially ferriannite decomposition by fO_2 increasing: Sld + O_2 rightarrow Fe-Ann + Qtz + Mag, Fe-Chm + Sld + O_2 rightarrow Fe-Ann + Qtz + Mag + H_2O and (2) with increasing temperature and siderite with ferroseladonite decomposition in carbonate bearing iron quartzites: Sld + Sd + Qtz rightarrow Fe-Ann + CO_2. The ribeckite occurrences are caused by relationship of the enriched Na^+ metamorphic fluid with the BIF rocks and are controlled by the variables: fO_2, aNa+ T ^oC (Miyano, Klein, 1983). If together with ribeckite siderite and ankerite are present, the ribeckite stability field is enlarged with the CO_2 activity decreasing. The ribeckite stability is not clear indicator of the metamorphic temperatures without considering other factors. The ribeckite (more exactly, fibrous variety - crocidolite) may crystallize through Fe-oxides, carbonates, and quartz decomposition during the low-grade metamorphism or diagenesis from 130 ^oC by the relationships Fe-rocks with Na^+ bearing solutions. The relatively large crystals alternating phyllosilicates appear through more high-grade metamorphism: Chl + Sld (Fe-Ann) + Na^+ rightarrow Rbk + Qtz + K^+ + H_2O. As a result reaction Rbk + Hem = Aeg + Mag + Qtz + H_2O high-grade ribeckite decomposition with the aegirine producing is occurred at 510-520^oC (Miyano, Beukes, 1997). However close paragenesis aegirine with the seladonite, tetraferribiotite, carbonates, and chlorites suppose that aegirine produce at more low temperatures (lower 400^oC) under conditions of high oxygen fugacity (2Rbk + O_2 = 4Aeg + 2Mag + 8Qtz + 2H_2O) and/or Na^+ activity in fluid (log[a(Na^+)/a(H^+)]>6.0) (Rbk + 4Hem + 23Na^+ = 4Aeg + 3Mag + 2H^+). Seladonite and tetraferribiotite inclusions in aegirine assume that these phases participate in aegirine producing reactions at oxygen fugacity increasing: Sld (or Fe-Ann) + Rbk + O_2 rightarrow Aeg + Mag + K^+. Acknowledgments This study was supported by the Integration Federal Program (project E0348), Universities of Russia Program, the Russian Foundation for Basic Research (project no. 02-05-64484, 00-05-64522). References Burt D.M. Vector representation of phyllosilicate compositions, Reviews in Mineralogy. (Ed. S.W. Baiey). 1989. V. 19. Cpt. 14. P. 584-599. Gole M.J. Mineralogy and petrology of very-low-metamorphic grade Archaean banded iron formations, Weld Range, Western Australia Amer. Miner. 1980. V. 65. P. 8-25. Laird J. Chlorites: metamorphic petrology, Reviews in Mineralogy. (Ed. S.W. Baiey). 1989. V. 19. Cpt. 11. P.405-453. Miyano T., Beukes N. J. Mineralogy and petrology of the contact metamorphosed amphibole asbestos-bearing Penge iron formation, Eastern Transvaal, South Africa// J. Petrol. 1997. V. 38. 5. P. 651-676. Miyano T., Klein C. Conditions of riebeckite formation in the iron-formation of the Dales Gorge Member, Hamersley Group, Western Australia// Amer. Mineral. 1983. V. 68. P. 517-529.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/443848','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/443848"><span id="translatedtitle"><span class="hlt">Magnetic</span> resonance imaging of cerebral <span class="hlt">anomalies</span> in subjects with resistance to thyroid hormone</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Leonard, C.M.; Hauser, P.; Weintraub, B.D. |</p> <p>1995-06-19</p> <p>Resistance to thyroid hormone (RTH) is an autosomal dominant disease caused by mutations in the human thyroid receptor beta gene on chromosome 3. Individuals with RTH have an increased incidence of attention deficit hyperactivity disorder (ADHD). The purpose of this study was to search for developmental brain malformations associated with RTH. Forty-three subjects (20 affected males [AM], 23 affected females [AF]) with resistance to thyroid hormone and 32 unaffected first degree relatives (18 unaffected males [UM], 14 unaffected females [UF]) underwent MRI brain scans with a volumetric acquisition that provided 90 contiguous 2 mm thick sagittal images. Films of six contiguous images beginning at a standard sagittal position lateral to the insula were analyzed by an investigator who was blind with respect to subject characteristics. The presence of extra or missing gyri in the parietal bank of the Sylvian fissure (multimodal association cortex) and multiple Heschl`s transverse gyri (primary auditory cortex) were noted. There was a significantly increased frequency of anomalous Sylvian fissures in the left hemisphere in males with RTH (AM: 70%; AF: 30%; UM: 28% UF: 28%). Also, there was an increased frequency of anomalous Sylvian fissures on the left combined with multiple Heschl`s gyri in either hemisphere in males with RTH (AM: 50%; AF: 9%; UM: 6%; UF: 0%). However, RTH subjects with <span class="hlt">anomalies</span> did not have an increased frequency of ADHD as compared with RTH subjects with no <span class="hlt">anomalies</span>. Abnormal thyroid hormone action in the male fetus early during brain development may be associated with grossly observable cerebral <span class="hlt">anomalies</span> of the left hemisphere. The effects of mutations in the thyroid receptor beta gene provide a model system for studying the complex interaction of genetic and non-genetic factors on brain and behavioral development. 19 refs., 2 figs., 2 tabs.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/973759','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/973759"><span id="translatedtitle">Beam <span class="hlt">spreading</span> and emittance oscillation of an intense <span class="hlt">magnetized</span> beam in free space.</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wang, C.-x.; Kim, K.-J.; Zhang, J. G.; Accelerator Systems Division; IIT</p> <p>2006-01-01</p> <p>Intense beams with large angular momentum have important applications in electron cooling and in producing flat beams suitable for ultrafast x-ray generation, Smith-Purcell radiators, and possibly for a future linear collider. To gain a basic understanding of the influence of beam angular momentum in an otherwise space-charge-dominated beam, the behavior of such a beam in free space will be examined here, in particular, beam <span class="hlt">spreading</span> due to space-charge force, as well as emittance oscillation. Drift space is an important part of a split photoinjector and plays a significant role in emitance compensation of a high-brightness photoinjector.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5558840','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5558840"><span id="translatedtitle">Aeromagnetic <span class="hlt">anomalies</span> and discordant lineations beneath the Niger Delta: Implications for new fracture zones and multiple sea-floor <span class="hlt">spreading</span> directions in the meso-Atlantic' Gulf of Guinea cul-de-sac</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Babalola, O.O.; Gipson, M. Jr. )</p> <p>1991-06-01</p> <p>An aeromagnetic contour map compiled over shallow water and onshore portions of the Nigerian continental margin, shows several elongate, long-wavelength <span class="hlt">anomaly</span> closures with some alternating polarity, separated by steep gradient, NE lineations. The lineations are interpreted as new fracture zones or extensions of previously mapped ones. The NE trend in the western delta region is concordant with the fracture zone trends of the deeper Gulf of Guinea. Aeromagnetic lineations of the SE Niger Delta Basin however, discordantly trend ENE. Their termination against the former, is interpreted as evidence of early sea-floor <span class="hlt">spreading</span> in a ENE-WSW direction in addition to the well documented NE-SW <span class="hlt">spreading</span> of the Gulf of Guinea and the rest of the meso-Atlantic sea-floor; The geophysical crustal structure indicate the existence of two Early Cretaceous triple junctions beneath the Niger Delta Basin. The two triple-junctions further support the hypothesis that the African continent was a multi-plate system (in the Niger Delta region) during the early opening of the Atlantic.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19820017717','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19820017717"><span id="translatedtitle">Investigations of medium wavelength <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> in the Eastern Pacific using MAGSAT data</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Harrison, C. G. A. (Principal Investigator)</p> <p>1982-01-01</p> <p>A paper which discusses a problem in representing the core <span class="hlt">magnetic</span> field of the Earth using spherical harmonics was revised and accepted for publications. Page proofs of a second paper concerning off center dipole modelling of the Earth's <span class="hlt">magnetic</span> field are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/15799040','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/15799040"><span id="translatedtitle">Visualization of cortical <span class="hlt">spreading</span> depression using manganese-enhanced <span class="hlt">magnetic</span> resonance imaging.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Henning, Erica C; Meng, Xiangjun; Fisher, Marc; Sotak, Christopher H</p> <p>2005-04-01</p> <p>Cortical <span class="hlt">spreading</span> depression (CSD) was visualized using manganese-enhanced MRI (MEMRI) following topical application of KCl to the exposed rat cortex. MEMRI signal increase in the ipsilateral cortex relative to the contralateral control region was 60 +/- 30% following two KCl applications. MEMRI signal increase for a single (40%) versus double (80%) KCl application suggests an integration effect over successive CSD episodes. CSD-induced MEMRI enhancement involved cortical layers containing dense regions of apical dendrites, supporting the contention that these neuronal structures are necessary for propagation of CSDs. Subcortical enhancement was present in hippocampal and thalamic regions, most likely a result of neuronal connections with cortical layers 4 and 5. These results are consistent with previous studies of CSD using diffusion-weighted MRI and T(2) (*)-weighted MRI and should be useful for investigating CSD itself and its role in other neurologic disorders. PMID:15799040</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005PhRvB..72e4436C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005PhRvB..72e4436C"><span id="translatedtitle"><span class="hlt">Anomalies</span> at the compensation temperature in the zero-<span class="hlt">magnetization</span> ferromagnet (Sm,Gd) Al2</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, X. H.; Wang, K. Q.; Hor, P. H.; Xue, Y. Y.; Chu, C. W.</p> <p>2005-08-01</p> <p>The unusual zero-<span class="hlt">magnetization</span> ferromagnet ( Sm1-x Gdx ) Al2 (SGA) with x=0.01 and 0.02 is investigated by <span class="hlt">magnetic</span>, and magnetotransport and calorimetric measurements. Striking features observed around the compensation temperature Tcomp are an exchange bias in a single-<span class="hlt">magnetic</span>-lattice compound such as SGA attributable to the anisotropy of the coupling between the spin and orbital moments; an anomalous Hall effect due to the asymmetric <span class="hlt">magnetic</span> scattering of the conduction electrons; and a field-induced specific heat transition at Tcomp ascribable to the field-induced switching of the spin and orbital moments in a polarized conduction electron sea. The observations reveal the richness of physics in the SGA compound system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.1068C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.1068C"><span id="translatedtitle">Earth's <span class="hlt">magnetic</span> field <span class="hlt">anomalies</span> that precede the M6+ global seismic activity</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cataldi, Gabriele; Cataldi, Daniele; Straser, Valentino</p> <p>2014-05-01</p> <p>In this work has been analyzed the Earth's <span class="hlt">magnetic</span> field variations and the M6+ global seismic activity to verify if M6+ earthquakes are preceded by a change of the Earth's <span class="hlt">magnetic</span> field. The data of Earth's <span class="hlt">magnetic</span> field used to conduct the study of correlation are provided by the induction magnetometer of Radio Emissions Project's station (Lat: 41°41'4.27"N, Long: 12°38'33,60"E, Albano Laziale, Rome, Italy), equipped with a ELF receiver prototype (with a vertically aligned coil antenna) capable to detect the variations of the intensity of the Earth's <span class="hlt">magnetic</span> field on Z <span class="hlt">magnetic</span> component. The M6+ global seismic activity data are provided in real-time by USGS, INGV and CSEM. The sample of data used to conduct the study refers to the period between 1 January 2012 and 31 December 2012. The Earth's <span class="hlt">magnetic</span> field variations data set has been marked with the times (time markers) of M6+ earthquakes occurred on a global scale and has been verified the existence of disturbances of the Earth's geomagnetic field in the time interval that preceded the M6+ global seismic activity. The correlation study showed that all M6+ earthquakes recorded on 2012 were preceded by an increase of the Earth's <span class="hlt">magnetic</span> field, detected in the Z <span class="hlt">magnetic</span> component. The authors measured the time lag elapsed between the maximum increment of the Earth's <span class="hlt">magnetic</span> field recorded before an earthquake M6+ and the date and time at which this occurred, and has been verified that the minimum time lag recorded between the Earth's <span class="hlt">magnetic</span> field increase and the earthquake M6+ has been 1 minute (9 October 2012, Balleny Islands, M6,4); while, the maximum time lag recorded has been 3600 minutes (26 June 2012, China, M6,3). The average time lag has been 629.47 minutes. In addition, the average time lag is deflected in relation to the magnitude increase. Key words: Seismic Geomagnetic Precursor (SGP), Interplanetary Seismic Precursor (ISP), Earth's <span class="hlt">magnetic</span> field variations, earthquakes, prevision.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..14.8983E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..14.8983E"><span id="translatedtitle">GMinterp, A Matlab Based Toolkit for Gravity and <span class="hlt">Magnetic</span> Data Analysis: Example Application to the Airborne <span class="hlt">Magnetic</span> <span class="hlt">Anomalies</span> of Biga Peninsula, NW Turkey</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ekinci, Y. L.; Yiǧitbaş, E.</p> <p>2012-04-01</p> <p>The analysis of gravity and <span class="hlt">magnetic</span> field methods is becoming increasingly significant for the earth sciences as a whole and these potential field methods efficiently assist in working out both shallow and deep geologic problems and play important role on modeling and interpretation procedures. The main advantage of some gravity and <span class="hlt">magnetic</span> data processing techniques is to present the subtle details in the data which are not clearly identified in <span class="hlt">anomaly</span> maps, without specifying any prior information about the nature of the source bodies. If the data quality permits, many analyzing techniques can be carried out that help to build a general understanding of the details and parameters of the shallower or deeper causative body distributions such as depth, thickness, lateral and vertical extensions. Gravity and <span class="hlt">magnetic</span> field data are usually analyzed by means of analytic signal (via directional derivatives) methods, linear transformations, regional and residual <span class="hlt">anomaly</span> separation techniques, spectral methods, filtering and forward and inverse modeling techniques. Some commercial software packages are commonly used for analyzing potential field data by employing some of the techniques specified above. Additionally, many freeware and open-source codes can be found in the literature, but unfortunately they are focused on special issues of the potential fields. In this study, a toolkit, that performs numerous interpretation and modeling techniques for potential field data, is presented. The toolkit, named GMinterp, is MATLAB-based consisting of a series of linked functions along with a graphical user interface (GUI). GMinterp allows performing complex processing such as transformations and filtering, editing, gridding, mapping, digitizing, extracting cross-sections, forward and inverse modeling and interpretation tasks. The toolkit enables to work with both profile and gridded data as an input file. Tests on the theoretically produced data showed the reliability of developed toolkit. Additionally some experiments on real data sets were performed to interpret the geological structure of Biga Peninsula, NW part of Anatolia, Turkey. Keywords: GMinterp, GUI, airborne <span class="hlt">magnetic</span> data, geology, Biga Peninsula</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014Tectp.624...32B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014Tectp.624...32B"><span id="translatedtitle">The Wallula fault and tectonic framework of south-central Washington, as interpreted from <span class="hlt">magnetic</span> and gravity <span class="hlt">anomalies</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Blakely, Richard J.; Sherrod, Brian L.; Weaver, Craig S.; Wells, Ray E.; Rohay, Alan C.</p> <p>2014-06-01</p> <p>The Yakima fold and thrust belt (YFTB) in central Washington has accommodated regional, mostly north-directed, deformation of the Cascadia backarc since prior to emplacement of Miocene flood basalt of the Columbia River Basalt Group (CRBG). The YFTB consists of two structural domains. Northern folds of the YFTB strike eastward and terminate at the western margin of a 20-mGal negative gravity <span class="hlt">anomaly</span>, the Pasco gravity low, straddling the North American continental margin. Southern folds of the YFTB strike southeastward, form part of the Olympic-Wallowa lineament (OWL), and pass south of the Pasco gravity low as the Wallula fault zone. An upper crustal model based on gravity and <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> suggests that the Pasco gravity low is caused in part by an 8-km-deep Tertiary basin, the Pasco sub-basin, abutting the continental margin and concealed beneath CRBG. The Pasco sub-basin is crossed by north-northwest-striking <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> caused by dikes of the 8.5 Ma Ice Harbor Member of the CRBG. At their northern end, dikes connect with the eastern terminus of the Saddle Mountains thrust of the YFTB. At their southern end, dikes are disrupted by the Wallula fault zone. The episode of NE-SW extension that promoted Ice Harbor dike injection apparently involved strike-slip displacement on the Saddle Mountains and Wallula faults. The amount of lateral shear on the OWL impacts the level of seismic hazard in the Cascadia region. Ice Harbor dikes, as mapped with aeromagnetic data, are dextrally offset by the Wallula fault zone a total of 6.9 km. Assuming that dike offsets are tectonic in origin, the Wallula fault zone has experienced an average dextral shear of 0.8 mm/y since dike emplacement 8.5 Ma, consistent with right-lateral stream offsets observed at other locations along the OWL. Southeastward, the Wallula fault transfers strain to the north-striking Hite fault, the possible location of the M 5.7 Milton-Freewater earthquake in 1936.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JAfES.115...85T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JAfES.115...85T"><span id="translatedtitle">The interpretation of <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> by 3D inversion: A case study from Central Iran</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tavakoli, M.; Nejati Kalateh, A.; Ghomi, S.</p> <p>2016-03-01</p> <p>The thick sedimentary units in Central Iran contain structures that form oil traps and are underlain by a basaltic layer which is amenable for study using its <span class="hlt">magnetic</span> susceptibility. The study and modeling of such sedimentary structures provide valuable exploratory information. In this study, we locate and interpret an underground <span class="hlt">magnetic</span> susceptibility interface using 3D non-linear inverse modeling of <span class="hlt">magnetic</span> data to make a better judgment in the context of hydrocarbon existence. The 3D structure is reconstructed by making it equal to a number of side by side rectangular hexahedrons or prisms and calculating their thicknesses such that the bottoms of the prisms are corresponding to the <span class="hlt">magnetic</span> susceptibility interface. By one of the most important mathematical tool in computational science, Taylor series, the non-linear problem changes to a linear problem near to initial model. In many inverse problems, we often need to invert large size matrices. To find the inverse of these matrices we use Singular Value Decomposition (SVD) method. The algorithm by an iterative method comparing model response with actual data will modify the initial guess of model parameters. The efficiency of the method and subprograms, programmed in MATLAB, has been shown by inverse modeling of free noise and noise-contaminated synthetic data. Finally, we inverted <span class="hlt">magnetic</span> field data from Garmsar area in Central Iran which the results were acceptable.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19820016644','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19820016644"><span id="translatedtitle">Spherical-earth Gravity and <span class="hlt">Magnetic</span> <span class="hlt">Anomaly</span> Modeling by Gauss-legendre Quadrature Integration</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Vonfrese, R. R. B.; Hinze, W. J.; Braile, L. W.; Luca, A. J. (Principal Investigator)</p> <p>1981-01-01</p> <p>The anomalous potential of gravity and <span class="hlt">magnetic</span> fields and their spatial derivatives on a spherical Earth for an arbitrary body represented by an equivalent point source distribution of gravity poles or <span class="hlt">magnetic</span> dipoles were calculated. The distribution of equivalent point sources was determined directly from the coordinate limits of the source volume. Variable integration limits for an arbitrarily shaped body are derived from interpolation of points which approximate the body's surface envelope. The versatility of the method is enhanced by the ability to treat physical property variations within the source volume and to consider variable <span class="hlt">magnetic</span> fields over the source and observation surface. A number of examples verify and illustrate the capabilities of the technique, including preliminary modeling of potential field signatures for Mississippi embayment crustal structure at satellite elevations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19830010868','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19830010868"><span id="translatedtitle">MAGSAT scalar <span class="hlt">anomalies</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Braile, L. W.; Hinze, W. J. (Principal Investigator)</p> <p>1982-01-01</p> <p>To facilitate processing large data arrays, elements of spherical Earth analysis programs NVERTSM, SMFLD, NVERTG and GLFD were implemented and tested on the LARS IBM 4341 computer. Currently, the problem of inverting 2 deg MAGSAT scalar <span class="hlt">anomalies</span> for the region (80 W, 60 E) longitude and (40 S, 70 N) latitude is being implemented on the LARS-computer for quantitative comparison with free air gravity <span class="hlt">anomaly</span>, geothermal and tectonic data. Gravity and MAGSAT <span class="hlt">anomalies</span> from a subset of this region (30 W, 60 E), (40 S, 70 N) were already processed for a paper on satellite <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> of Africa and Europe.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/1003440','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/1003440"><span id="translatedtitle">Observation of a New <span class="hlt">Magnetic</span> <span class="hlt">Anomaly</span> Below the Ferromagnetic Curie Temperature in Yb<sub>14</sub>MnSb<sub>11</sub></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Srinath, S.; Poddar, P.; Srikanth, H.; Sales, Brian C; Mandrus, David</p> <p>2005-01-01</p> <p>Yb{sub 14}MnSb{sub 11} is an unusual ferromagnet with a Curie temperature of 52 {+-} 1 K. Recent optical, Hall, <span class="hlt">magnetic</span>, and thermodynamic measurements indicate that Yb{sub 14}MnSb{sub 11} may be a rare example of an underscreened Kondo lattice. We report the first experimental observation of a new <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> in this system at around 47 K, a few degrees below T{sub c}. Systematic investigations of the ac and dc susceptibilities of Yb{sub 14}MnSb{sub 11} single crystals reveal features associated with possible spin reorientation at this temperature. This new <span class="hlt">anomaly</span> is extremely sensitive to the applied measurement field and is absent in temperature-dependent dc <span class="hlt">magnetization</span> data for fields above 50 Oe. The origin of this could be due to decoupling of two distinct <span class="hlt">magnetic</span> sublattices associated with MnSb{sub 4} tetrahedra.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70012210','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70012210"><span id="translatedtitle">Calculation of gravity and <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> of finite-length right polygonal prisms.</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Cady, J.W.</p> <p>1980-01-01</p> <p>An equation is derived for the vertical gravity field due to a homogeneous body with polygonal cross‐section and finite strike‐length. The equation can be separated into the two‐dimensional (2-D) terms of Talwani et al. (1959) and exact terms for the contributions of the ends of the prism. Equations for the <span class="hlt">magnetic</span> field due to a similar body were derived by Shuey and Pasquale (1973), who coined the term “two‐and‐a‐half dimensional” (2 1/2-D) to describe the geometry. <span class="hlt">Magnetic</span> intensities are expressed as a vector sum, from which the common dot product formulation can be obtained by binomial expansion.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015E%26PSL.430...54D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015E%26PSL.430...54D"><span id="translatedtitle">Global equivalent <span class="hlt">magnetization</span> of the oceanic lithosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dyment, J.; Choi, Y.; Hamoudi, M.; Lesur, V.; Thebault, E.</p> <p>2015-11-01</p> <p>As a by-product of the construction of a new World Digital <span class="hlt">Magnetic</span> <span class="hlt">Anomaly</span> Map over oceanic areas, we use an original approach based on the global forward modeling of seafloor <span class="hlt">spreading</span> <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> and their comparison to the available marine <span class="hlt">magnetic</span> data to derive the first map of the equivalent <span class="hlt">magnetization</span> over the World's ocean. This map reveals consistent patterns related to the age of the oceanic lithosphere, the <span class="hlt">spreading</span> rate at which it was formed, and the presence of mantle thermal <span class="hlt">anomalies</span> which affects seafloor <span class="hlt">spreading</span> and the resulting lithosphere. As for the age, the equivalent <span class="hlt">magnetization</span> decreases significantly during the first 10-15 Myr after its formation, probably due to the alteration of crustal <span class="hlt">magnetic</span> minerals under pervasive hydrothermal alteration, then increases regularly between 20 and 70 Ma, reflecting variations in the field strength or source effects such as the acquisition of a secondary <span class="hlt">magnetization</span>. As for the <span class="hlt">spreading</span> rate, the equivalent <span class="hlt">magnetization</span> is twice as strong in areas formed at fast rate than in those formed at slow rate, with a threshold at ∼40 km/Myr, in agreement with an independent global analysis of the amplitude of <span class="hlt">Anomaly</span> 25. This result, combined with those from the study of the anomalous skewness of marine <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>, allows building a unified model for the <span class="hlt">magnetic</span> structure of normal oceanic lithosphere as a function of <span class="hlt">spreading</span> rate. Finally, specific areas affected by thermal mantle <span class="hlt">anomalies</span> at the time of their formation exhibit peculiar equivalent <span class="hlt">magnetization</span> signatures, such as the cold Australian-Antarctic Discordance, marked by a lower <span class="hlt">magnetization</span>, and several hotspots, marked by a high <span class="hlt">magnetization</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=pacific+AND+oceanography&pg=2&id=EJ386134','ERIC'); return false;" href="http://eric.ed.gov/?q=pacific+AND+oceanography&pg=2&id=EJ386134"><span id="translatedtitle">An Exercise on <span class="hlt">Magnetic-Anomaly</span> Profiles and the Geomagnetic Polar-Reversal Time Scale.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Shea, James Herbert</p> <p>1988-01-01</p> <p>Develops an exercise in which students use <span class="hlt">magnetic</span>-profile data gathered in the South Pacific to test the Vine-Matthews-Morley hypothesis. Uses the Eltanin 19N and 20N profiles. Relates the exercise to 20 current geology texts. (MVL)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5256687','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5256687"><span id="translatedtitle">Formation of <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> antipodal to lunar impact basins: Two-dimensional model calculations</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hood, L.L.; Huang, Z. )</p> <p>1991-06-10</p> <p>The production of large-scale <span class="hlt">magnetic</span> fields and associated crustal <span class="hlt">magnetization</span> in lunar basin-forming impacts is investigated theoretically. Two-dimensional numerical models of the partially ionized vapor cloud produced in such impacts show that the low-density periphery of the cloud expands thermally around the Moon and converges near the antipode in a time of the order of 400 to 500 s for silicate impactor velocities of 15 to 20 km/s. Fields external to the impact plasma cloud are produced by the magnetohydrodynamic interaction of the cloud with ambient <span class="hlt">magnetic</span> fields and plasmas. For the most typical case in which the Moon is immersed in the solar wind plasma and its embedded <span class="hlt">magnetic</span> field, an MHD shock wave forms upstream of the cloud periphery separating the shocked solar wind from the free-stream solar wind. For impacts occurring on the downstream (antisunward) hemisphere, convergence of the impact plasma cloud and associated MHD shock waves occurs on the upstream side and results in a large antipodal field amplification. For impacts occurring on the upstream (sunward) hemisphere, some antipodal field amplification is still expected due to the finite electrical conductivity of the lunar interior (requiring an induced external <span class="hlt">magnetic</span> field) and the likely presence of some residual plasma in the wake of the impact plasma cloud. During the period of compressed antipodal field amplification, seismic compressional waves from the impact converge at the antipode resulting in transient shock pressures that have been calculated to be as large as 2 GPa (20 kbar).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70037335','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70037335"><span id="translatedtitle">The Mackenzie River <span class="hlt">magnetic</span> <span class="hlt">anomaly</span>, Yukon and Northwest Territories, Canada-Evidence for Early Proterozoic magmatic arc crust at the edge of the North American craton</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Pilkington, M.; Saltus, R.W.</p> <p>2009-01-01</p> <p>We characterize the nature of the source of the high-amplitude, long-wavelength, Mackenzie River <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> (MRA), Yukon and Northwest Territories, Canada, based on <span class="hlt">magnetic</span> field data collected at three different altitudes: 300??m, 3.5??km and 400??km. The MRA is the largest amplitude (13??nT) satellite <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> over Canada. Within the extent of the MRA, source depth estimates (8-12??km) from Euler deconvolution of low-altitude aeromagnetic data show coincidence with basement depths interpreted from reflection seismic data. Inversion of high-altitude (3.5??km) aeromagnetic data produces an average <span class="hlt">magnetization</span> of 2.5??A/m within a 15- to 35-km deep layer, a value typical of magmatic arc complexes. Early Proterozoic magmatic arc rocks have been sampled to the southeast of the MRA, within the Fort Simpson <span class="hlt">magnetic</span> <span class="hlt">anomaly</span>. The MRA is one of several broad-scale <span class="hlt">magnetic</span> highs that occur along the inboard margin of the Cordillera in Canada and Alaska, which are coincident with geometric changes in the thrust front transition from the mobile belt to stable cratonic North America. The inferred early Proterozoic magmatic arc complex along the western edge of the North American craton likely influenced later tectonic evolution, by acting as a buttress along the inboard margin of the Cordilleran fold-and-thrust belt. Crown Copyright ?? 2008.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140010435','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140010435"><span id="translatedtitle">Particle-In-Cell Simulations of the Solar Wind Interaction with Lunar Crustal <span class="hlt">Magnetic</span> <span class="hlt">Anomalies</span>: <span class="hlt">Magnetic</span> Cusp Regions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Poppe, A. R.; Halekas, J. S.; Delory, G. T.; Farrell, W. M.</p> <p>2012-01-01</p> <p>As the solar wind is incident upon the lunar surface, it will occasionally encounter lunar crustal remanent <span class="hlt">magnetic</span> fields. These <span class="hlt">magnetic</span> fields are small-scale, highly non-dipolar, have strengths up to hundreds of nanotesla, and typically interact with the solar wind in a kinetic fashion. Simulations, theoretical analyses, and spacecraft observations have shown that crustal fields can reflect solar wind protons via a combination of <span class="hlt">magnetic</span> and electrostatic reflection; however, analyses of surface properties have suggested that protons may still access the lunar surface in the cusp regions of crustal <span class="hlt">magnetic</span> fields. In this first report from a planned series of studies, we use a 1 1/2-dimensional, electrostatic particle-in-cell code to model the self-consistent interaction between the solar wind, the cusp regions of lunar crustal remanent <span class="hlt">magnetic</span> fields, and the lunar surface. We describe the self-consistent electrostatic environment within crustal cusp regions and discuss the implications of this work for the role that crustal fields may play regulating space weathering of the lunar surface via proton bombardment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19940033517&hterms=Magnetic+interaction&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DTitle%26N%3D0%26No%3D20%26Ntt%3DMagnetic%2Binteraction','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19940033517&hterms=Magnetic+interaction&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DTitle%26N%3D0%26No%3D20%26Ntt%3DMagnetic%2Binteraction"><span id="translatedtitle">Observational test of hot flow <span class="hlt">anomaly</span> formation by the interaction of a <span class="hlt">magnetic</span> discontinuity with the bow shock</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Thomsen, M. F.; Thomas, V. A.; Winske, D.; Gosling, J. T.; Farris, M. H.; Russell, C. T.</p> <p>1993-01-01</p> <p>The formation of a hot flow <span class="hlt">anomaly</span> (HFA) observed near the Earth's bow shock appears to be due to the interaction between the bow shock and an impinging discontinuity in the upstream plasma. Recent single-particle and 2D hybrid numerical studies have suggested that such an interaction will produce an HFA only if the motional electric field in the ambient plasma points toward the discontinuity, thereby focusing shock-reflected ions into it. We perform a test of this electric field orientation for a set of nine HFA events observed by the ISEE spacecraft and described previously in the literature. Under the assumption that the discontinuities were tangential, the predicted electric field orientation is found on at least one side of all nine observed HFAs (on the trailing edge of seven and the leading edge of five, and on both sides of three events). Further, there is evidence that asymmetries in the observed <span class="hlt">magnetic</span> field signatures are related to the orientation of the motional electric field. The events in which the electric field points toward the discontinuity on both sides tend to be those with fairly symmetric flanking <span class="hlt">magnetic</span> field enhancements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19910053842&hterms=Magnesium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DMagnesium','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19910053842&hterms=Magnesium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DMagnesium"><span id="translatedtitle">Positive holes in magnesium oxide - Correlation between <span class="hlt">magnetic</span>, electric, and dielectric <span class="hlt">anomalies</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Batllo, F.; Leroy, R. C.; Parvin, K.; Freund, F.; Freund, M. M.</p> <p>1991-01-01</p> <p>The present <span class="hlt">magnetic</span> susceptibility investigation of high purity MgO single crystals notes an anomally at 800 K which is associated with increasing electrical conductivity, a rise in static dielectric constant from 9 to 150, and the appearance of a pronounced positive surface charge. These phenomena can be accounted for in terms of peroxy defects which represent self-trapped, spin-paired positive holes at Mg(2+) vacancy sites. The holes begin to decouple their spins above 600 K.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19850044273&hterms=Curie&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DCurie','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19850044273&hterms=Curie&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DCurie"><span id="translatedtitle">Curie isotherm surfaces inferred from high-altitude <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> data</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mayhew, M. A.</p> <p>1985-01-01</p> <p>Two-dimensional Curie depth models along two sections across the western United States are derived using an equivalent layer <span class="hlt">magnetization</span> model derived from Magsat data, and the results are used to constrain finite element thermal models developed by Mayhew and Majer (1980). Regional heat flow variations predicted by the models compare favorably with those inferred from direct measurements. The methodology is applied to upward-continued aeromagnetic data, and the results are found to be in good agreement with previous Curie depth estimates and average measured heat flow.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000SPIE.4039...70C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000SPIE.4039...70C"><span id="translatedtitle">Enhanced <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> detection using a nitrogen-cooled superconducting gradiometer</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Clem, Ted R.; Overway, David J.; Purpura, John W.; Bono, John T.; Carroll, Paul J.; Koch, Roger H.; Rozen, James R.; Keefe, George A.; Willen, Scott; Mohling, Robert A.</p> <p>2000-07-01</p> <p>During the 1980's the Superconducting Gradiometer/Magnetometer Sensor was demonstrated in the <span class="hlt">Magnetic</span> and Acoustic Detection of Mines Advanced Technology Demonstration to provide effective mine detection, localization, and classification capabilities, especially against buried mines, and to reduce significantly acoustic false alarms arising from bottom clutter. This sensor utilized Superconducting Quantum Interference Devices manufactured using the low critical temperature (low Tc) superconductor niobium and liquid helium for sensor cooling. This sensor has most recently bee integrated into the Mobile Underwater Debris Survey System and has been demonstrated successfully in a survey to locate unexploded ordnance in coastal waters.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5021702','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5021702"><span id="translatedtitle">Influence of the equatorial irregularities and precipitations in the South Atlantic <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> on the generation of auroral-type plasma instabilities</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Prange, R.; Bruston, P.</p> <p>1980-08-01</p> <p>Observational evidence of upward field-aligned beams in the keV range has been obtained in the sub-equatorial ionosphere above South America. These events can be related to coupled <span class="hlt">magnetic</span> and ionospheric activity (<span class="hlt">magnetic</span> storm, ionospheric irregularities). This result is in opposition with the current theory of the low-latitude ionosphere. Its interpretation must assume that conditions exist for the growth of plasma instabilities. This implies a low plasma density, a close coupling between the ionosphere and the magnetosphere, and field-aligned currents. Such suitable conditions have independently been observed in ionospheric irregularities (density, currents) or during <span class="hlt">magnetic</span> storms (energetic particle precipitation) or they are deduced from the structure of the <span class="hlt">Anomaly</span> (field-aligned currents). This allows us to suggest that the South Atlantic <span class="hlt">Anomaly</span> sometimes compares to the auroral oval and may develop some current-driven plasma instabilities.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JESS..123.1273R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JESS..123.1273R"><span id="translatedtitle"><span class="hlt">Spread</span>-F during the <span class="hlt">magnetic</span> storm of 22 January 2004 at low latitudes: Effect of IMF-Bz in relation to local sunset time</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rastogi, R. G.; Chandra, H.; Janardhan, P.; Hoang, Thai Lan; Condori, Louis; Pant, T. K.; Prasad, D. S. V. V. D.; Reinisch, B.</p> <p>2014-08-01</p> <p>The paper describes the results of <span class="hlt">spread</span>-F at low latitude stations around the world during the <span class="hlt">magnetic</span> storm starting at 0130 UT on 22 January 2004. The storm can be divided into two phases, first phase up to 1000 UT when interplanetary <span class="hlt">magnetic</span> field IMF-Bz was highly fluctuating around a small positive value and the second phase after a sudden large southward turning of IMF-Bz at 1030 UT. The first phase produced strong <span class="hlt">spread</span>-F at Jicamarca, Sao Luis, and Ascension Island and caused complete inhibition of <span class="hlt">spread</span>-F at Thumba and Waltair in India. It generated weak <span class="hlt">spread</span>-F at Ho Chi Minh City in Vietnam and strong <span class="hlt">spread</span>-F at Hainan and Chung Li. The strong <span class="hlt">spread</span>-F at Hainan and Chung Li were caused by the positive IMF-Bz during the first phase of the storm and not by the negative pulse of IMF-Bz at 1000 UT.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014Tectp.624...24M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014Tectp.624...24M"><span id="translatedtitle">Remanent <span class="hlt">magnetization</span> in fresh xenoliths derived from combined demagnetization experiments: <span class="hlt">Magnetic</span> mineralogy, origin and implications for mantle sources of <span class="hlt">magnetic</span> <span class="hlt">anomalies</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Martin-Hernandez, Fatima; Ferré, Eric C.; Friedman, Sarah A.</p> <p>2014-06-01</p> <p>Fresh mantle xenoliths represent an exceptional opportunity to directly access Earth's interior. In particular, <span class="hlt">magnetic</span> signals carried by upper mantle xenoliths may provide the only opportunity to determine the depth of remanent <span class="hlt">magnetization</span> below the Moho boundary. In recent years, the nature, intensity and <span class="hlt">magnetic</span> properties of the <span class="hlt">magnetic</span> signal have been characterized by measurements of the 0020 induced <span class="hlt">magnetization</span> in hysteresis loops. The natural remanent <span class="hlt">magnetization</span> (NRM) intensity, despite providing the first indication of the <span class="hlt">magnetic</span> nature of magnetite inclusions, has not been studied in detail. This study focusses attention on the number of recorded NRM directions and characteristics of the anhysteretic remanent <span class="hlt">magnetization</span> (ARM) and saturation isothermal remanent <span class="hlt">magnetization</span> (SIRM) demagnetization spectra. A collection of 17 extremely fresh mantle xenoliths has been subjected to AF demagnetization, characterizing samples with one, two or three populations of remanence carriers, with differing coercivities, that are potential carriers of <span class="hlt">magnetization</span> at mantle depths.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFM.T31A2147S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.T31A2147S"><span id="translatedtitle">Opening of the Amerasian Basin: A model based on sea-floor morphology, <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> and paleomagnetic data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stone, D. B.; Brumley, K.</p> <p>2010-12-01</p> <p>There are numerous models for the origins of the Amerasia Basin. The model we present here is based on sea-floor morphology, <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> signatures and evidence derived from dredge hauls which indicate that the Arctic Alaska block traveled to its present location from a location close to the Canadian and Lomonosov margins. This location is further east than is called for by the conventional “windshield wiper” model. The paleomagnetic database that relates directly to the origins of the Arctic Ocean consists of a study of Cretaceous sediments (135Ma) from the northern coastal region of Alaska (Kuparuk oil field drill core) and younger sediments (100Ma) from the west end of the Arctic coastal plain (Utukok River area) plus volcanic rocks from the Okhotsk-Chukotka volcanic belt (67-90Ma). The pole positions derived from the sedimentary sequences from Alaska require a model involving both rotation and translation. We have also incorporated paleomagnetic paleolatitudes derived from borehole cores (no declination control), and inferred paleolatitudes based on the pervasive <span class="hlt">magnetic</span> overprint found throughout Arctic Alaska. These data sets are also consistent with the translation plus rotation model presented. In most models the location of Chukotka is depicted as being more or less fixed with respect to Arctic Alaska, but the paleomagnetic poles determined for the Okhotsk-Chukotka volcanic suites are hard to reconcile with the paleogeography proposed here if Chukotka remains firmly attached to Arctic Alaska. The Chukotka data require that the volcanic belt was erupted at more northerly latitudes than its present location, thus it appears to have moved somewhat independently from Alaska. Looking to the future it would seem that the Okhotsk-Chukotka volcanic belt should be a prime target for paleomagnetic work. It is relatively accessible, and in contrast to the bulk of the sedimentary sections sampled in Northern Alaska, these rocks have proven to be good paleomagnetic recorders.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004cosp...35.3590B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004cosp...35.3590B"><span id="translatedtitle">lower ionosphere cosmic noise absorption responses to the interplanetary <span class="hlt">magnetic</span> field behavior in the south atlantic <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> and sub-auroral regions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brum, C. G. M.; Abdu, M. A.; Batista, I. S.; Santos, P. M. T.; Barros, L. P.</p> <p></p> <p>The interplanetary <span class="hlt">magnetic</span> field (IMF) plays an important role in the cosmic ray flux modulation that reaches the lower ionosphere, which is one of the main sources of the ionization in these regions. In this work, it is presented data analysis results obtained from riometers operating at 30 MHz over Cachoeira Paulista (located at South Atlantic <span class="hlt">Magnetic</span> <span class="hlt">Anomaly</span> (SAMA) - connected to an antenna pointed to the zenith direction, 22.50°S; 45.00°W) and the Brazilian Antarctic Station - EACF (connected to an antenna pointed to the zenith and geomagnetic west directions, 62.56°S; 58.39°W) during almost one complete solar cycle (1989-1996). Previous results have shown that there is a strong correlation between the cosmic noise absorption (CNA) behavior and the IMF. Basically, the sub-auroral region presents a decrease in the CNA with the increase of the IMF intensity, while in the SAMA region, for the same IMF conditions, it was registered an increase. Related to the IMF direction, the greater values of CNA are present when the IMF is pointed to the south and to the east for EACF and AMAS regions, respectively. The results of these data analysis are discussed and the galactic cosmic noise absorption is computed by using the geomagnetic activity (geomagnetic field values) to show the relationship between CNA and IMF behavior.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008GeoJI.174..825D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008GeoJI.174..825D"><span id="translatedtitle">Toward a minimum change model for recent plate motions: calibrating seafloor <span class="hlt">spreading</span> rates for outward displacement</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>DeMets, C.; Wilson, D. S.</p> <p>2008-09-01</p> <p>We use seafloor <span class="hlt">spreading</span> distances derived from reconstructions of more than 7000 crossings of young <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> along seven plate boundaries to study outward displacement, a source of systematic bias in estimates of seafloor <span class="hlt">spreading</span> rates, which is caused by a combination of processes that shift <span class="hlt">magnetic</span> polarity transition zones away from their idealized locations. Linear regressions of 81 independent sequences of seafloor opening distances as a function of their <span class="hlt">magnetic</span> reversal ages for <span class="hlt">anomalies</span> younger than C3n.1 (4.19 Ma) yield 75 positively valued intercepts for zero seafloor age, confirming the ubiquitous outward shift of <span class="hlt">magnetic</span> reversals reported by previous authors. Grouping these data into 29 locally consistent clusters yields better constrained zero-age intercepts that are uniformly positive and average 2.2 +/- 0.3 km globally. These values, which are 1-3 km at most locations and are significantly larger (3-5 km) along the well-surveyed Reykjanes and Carlsberg ridges, agree well with published <span class="hlt">magnetic</span> polarity zone transition widths, which are estimated directly from near-bottom seafloor <span class="hlt">magnetic</span> measurements. Significant variations in outward displacement along the Southeast Indian Ridge are strongly correlated with changes in axial morphology and axial depth; however, a similar correlation is not observed along other ridges. Forward <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> modelling suggests that variations in outward displacement can be explained by differences in the <span class="hlt">magnetic</span> source layers that are assumed to characterize different <span class="hlt">spreading</span> centres. If not corrected for outward displacement, the implied systematic upward biases in seafloor <span class="hlt">spreading</span> rates, which are averaged over the width of <span class="hlt">Anomaly</span> 1-the youngest reversal that is used for plate reconstructions-range from 6 mm yr-1 along the Reykjanes Ridge, where outward displacement is 4-5 km, to 3 mm yr-1 along ridges where outward displacement approximates the global average of 2 km.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMGP51C1094S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMGP51C1094S"><span id="translatedtitle">Gravity and <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> used to delineate geologic features associated with earthquakes and aftershocks in the central Virginia seismic zone</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shah, A. K.; Horton, J.; McNamara, D. E.; Spears, D.; Burton, W. C.</p> <p>2013-12-01</p> <p>Estimating seismic hazard in intraplate environments can be challenging partly because events are relatively rare and associated data thus limited. Additionally, in areas such as the central Virginia seismic zone, numerous pre-existing faults may or may not be candidates for modern tectonic activity, and other faults may not have been mapped. It is thus important to determine whether or not specific geologic features are associated with seismic events. Geophysical and geologic data collected in response to the Mw5.8 August 23, 2011 central Virginia earthquake provide excellent tools for this purpose. Portable seismographs deployed within days of the main shock showed a series of aftershocks mostly occurring at depths of 3-8 km along a southeast-dipping tabular zone ~10 km long, interpreted as the causative fault or fault zone. These instruments also recorded shallow (< 4 km) aftershocks clustered in several areas at distances of ~2-15 km from the main fault zone. We use new airborne geophysical surveys (gravity, <span class="hlt">magnetics</span>, radiometrics, and LiDAR) to delineate the distribution of various surface and subsurface geologic features of interest in areas where the earthquake and aftershocks took place. The main (causative fault) aftershock cluster coincides with a linear, NE-trending gravity gradient (~ 2 mgal/km) that extends over 20 km in either direction from the Mw5.8 epicenter. Gravity modeling incorporating seismic estimates of Moho variations suggests the presence of a shallow low-density body overlying the main aftershock cluster, placing it within the upper 2-4 km of the main-fault hanging wall. The gravity, <span class="hlt">magnetic</span>, and radiometric data also show a bend in generally NE-SW orientation of <span class="hlt">anomalies</span> close to the Mw5.8 epicenter. Most shallow aftershock clusters occur near weaker short-wavelength gravity gradients of one to several km length. In several cases these gradients correspond to geologic contacts mapped at the surface. Along the gravity gradients, the aftershocks appear to cluster near areas with cross-cutting geologic features such as Jurassic diabase dikes. These associations suggest that local variations in rock density and/or rheology may have contributed to modifications of local stress regimes in a manner encouraging localized seismicity associated with the Mw5.8 event and its aftershocks. Such associations are comparable to results of previous studies recognizing correspondences between seismicity and features such as intrusive bodies and failed rifts in the New Madrid seismic zone and elsewhere. To explore whether similar correspondences may have occurred in the past, we use regional gravity and <span class="hlt">magnetic</span> data to consider possible relations between historical earthquakes and comparable geologic features elsewhere in the central Virginia seismic zone.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JHEP...03..077N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JHEP...03..077N"><span id="translatedtitle"><span class="hlt">Anomalies</span> and entanglement entropy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nishioka, Tatsuma; Yarom, Amos</p> <p>2016-03-01</p> <p>We initiate a systematic study of entanglement and Rényi entropies in the presence of gauge and gravitational <span class="hlt">anomalies</span> in even-dimensional quantum field theories. We argue that the mixed and gravitational <span class="hlt">anomalies</span> are sensitive to boosts and obtain a closed form expression for their behavior under such transformations. Explicit constructions exhibiting the dependence of entanglement entropy on boosts is provided for theories on spacetimes with non-trivial <span class="hlt">magnetic</span> fluxes and (or) non-vanishing Pontryagin classes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19820016723','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19820016723"><span id="translatedtitle">MAGSAT <span class="hlt">anomaly</span> map and continental drift</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lemouel, J. L. (Principal Investigator); Galdeano, A.; Ducruix, J.</p> <p>1981-01-01</p> <p><span class="hlt">Anomaly</span> maps of high quality are needed to display unambiguously the so called long wave length <span class="hlt">anomalies</span>. The <span class="hlt">anomalies</span> were analyzed in terms of continental drift and the nature of their sources is discussed. The map presented confirms the thinness of the oceanic <span class="hlt">magnetized</span> layer. Continental <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> are characterized by elongated structures generally of east-west trend. Paleomagnetic reconstruction shows that the <span class="hlt">anomalies</span> found in India, Australia, and Antarctic exhibit a fair consistency with the African <span class="hlt">anomalies</span>. It is also shown that <span class="hlt">anomalies</span> are locked under the continents and have a fixed geometry.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004AGUSMGP14A..04F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004AGUSMGP14A..04F"><span id="translatedtitle"><span class="hlt">Magnetic</span> Field <span class="hlt">Anomalies</span> Recorded Prior to the M=7.6 Chi-Chi Earthquake in Taiwan, Inferred Ground Currents, and the Electrical Conductivity of Rocks</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Freund, F. T.; Yen, H.; Chen, C.; Bellavia, D.; Hall, C.; Takeuchi, A.; Lau, B. W.</p> <p>2004-05-01</p> <p>During seven weeks before the M=7.6 Chi-Chi earthquake in Taiwan on Sept. 21, 1999 and during the month-long aftershock sequence, strong <span class="hlt">magnetic</span> field <span class="hlt">anomalies</span> were recorded by two ground stations LY and TT close to the 100 km long, N-S trending fault line that broke during the Chi-Chi event. The <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> occurred in hour-long pulses and reached total field intensities of 200 nT (above a 5 nT background). They imply powerful E-W trending ground currents of the order of 500,000 Amp. Assuming the <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> to arise from a linear source, the signal strength at satellite altitudes of 300-700 km is estimated to be of the order of 3.3 - 1.5 pT, respectively. Modeling the ground conductor we find current densities of the order of 0.1 mAmp per square meter. We report on a laboratory study to measure the electrical conductivity of igneous rocks placed under stress. We find that the increase in conductivity is due to electronic charge carriers, which are positive holes (p-holes), e.g. defect electrons in the valence band of the otherwise insulating minerals. The current densities obtained from the rock deformation experiments are of the same order of magnitude as those inferred from modeling the Chi-Chi ground conductor.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.T51A2557P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.T51A2557P"><span id="translatedtitle">Crustal thickness and Vp/Vs estimates near the Brunswick <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> using receiver functions from the SESAME array</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Parker, E. H.; Hawman, R. B.; Fischer, K. M.; Wagner, L. S.</p> <p>2012-12-01</p> <p>The Southeastern Suture of the Appalachian Margin Experiment (SESAME) is designed to investigate lithospheric dynamics associated with the Paleozoic collision between the Suwanee terrane and Laurentia as well as subsequent Mesozoic rifting and passive margin formation. So far, we have deployed 63 broadband instruments along two N-S trending profiles across Georgia and northern Florida. A third NW-trending profile consisting of 19 stations extends across accreted terranes of the southern Appalachians from Augusta, GA to eastern TN. The N-S profiles are intended to provide constraints on variations in crustal structure across the Brunswick <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> (BMA), a prominent <span class="hlt">magnetic</span> low coinciding with south-dipping crustal-scale seismic reflectors evident on COCORP profiles in south Georgia. The seismic reflectivity is likely a consequence of suturing, but the BMA has been interpreted as an edge effect related to collision as well as an effect of mafic magmatism south of the suture zone. H-k stacking using 10 teleseismic receiver functions from station W27, located ~50-km north of the suture on the western N-S profile, suggests a crustal thickness (H) of 42-44 km and average crustal Vp/Vs (k) of 1.73-1.80. These estimates are in agreement with previous well-constrained stacking results from USNSN station GOGA, located ~70-km to the northeast, that suggest a crustal thickness of 41-43 km and average Vp/Vs 1.72-1.76. The proposed suture zone itself lies beneath sediments of the Atlantic Coastal Plain, and receiver functions from stations in this region appear to be strongly affected by high-amplitude reverberations within the sedimentary column. Therefore, preliminary H-k stacking results from stations directly over the BMA may be unreliable. However, receiver functions from station W23 near the Inner Piedmont-Coastal Plain boundary (near the north, up-dip end of the suture zone) display variations in Ps delay time and amplitude with event back-azimuth. Receiver functions from the S-azimuth (South American trench) display a relatively weak Ps conversion at ~4 seconds, while receiver functions from the NW-azimuth (Aleutian trench) show a more complex signal with an arrival at ~4 s followed by a higher-amplitude arrival at ~6 seconds. This may be indicative of compositional heterogeneity across the suture, anisotropy within the crust or mantle, or complexity at the crust-mantle interface related to collision of the Suwanee terrane. Forthcoming data from additional stations will provide improved constraints on crustal structure across the BMA.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFM.T31A2124S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.T31A2124S"><span id="translatedtitle">Gravity and <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> of the western Arctic ocean and its margins provide an imperfect window to a complex, multi-stage tectonic history (Invited)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Saltus, R. W.; Miller, E. L.; Gaina, C.</p> <p>2010-12-01</p> <p>Numerous scenarios are still in play for the tectonic development of the western Arctic. A wide range of kinematic models have been proposed for the opening of the Canadian basin. These models feature different combinations and geometries of extensional and transform motion and have informal descriptive names including the so-called ‘windshield wiper’, ‘railroad tracks’, ‘squeegee’, and ‘saloon door’ options. Another controversial issue is the timing and role of the gigantic Alpha-Mendeleev large igneous province relative to the tectonic stages. In our opinion, many current Arctic models have not adequately dealt with the mass and thermal fluxes implied by this huge province. Available data are extremely sparse for the circum-Arctic, although current political and economic interests are fueling accelerated data collection. Recent compilations of gravity and <span class="hlt">magnetic</span> data are currently the best bets for synoptic imaging, however imprecise, of crustal composition and structure. Modeling and interpretation of regional geophysical <span class="hlt">anomalies</span> provide some of the only available tests for scenario evaluation in the absence of more direct determinations of crustal structure and composition. Our goal in this talk is to review the key geophysical features of the western Arctic and relate these elements to the expectations of competing tectonic models. These key geophysical features include (1) contrasting Arctic domains of overall <span class="hlt">magnetic</span> “thickness” and <span class="hlt">anomaly</span> “fabric” (the domains correlate generally with broad tectonic categories); (2) cryptic sub-linear <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> in the Canada basin (interpreted by some authors to be oceanic stripes); (3) a subtle but persistent gravity trough in the central Canada basin (inferred by some authors to represent an extensional trough); (4) spectacular “shelf edge” free-air gravity <span class="hlt">anomalies</span> along the Canadian and Alaskan passive margins that show significant along-strike variation (which can be interpreted to reflect relative amount of magmatic activity); (5) complex and chaotic <span class="hlt">magnetic</span> texture and fabric in the Alpha-Mendeleev large igneous province (perhaps reflecting pre-intrusive structural features and trends); and (6) large-amplitude, long-wavelength “deep <span class="hlt">magnetic</span> highs” including well-studied examples in northern Alaska and north-western Canada (inferred to represent deep crustal elements that influence overall strength of the crust/upper mantle). The overall complexity of the Arctic geophysical <span class="hlt">anomaly</span> fabric is indicative of significant variation in crustal composition and reflects a complicated, multi-stage tectonic development. It seems very likely that the best tectonic solutions for the circum-Arctic will include sub-elements of many current end-member models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JGRE..118.1265H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JGRE..118.1265H"><span id="translatedtitle">Origin of strong lunar <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>: Further mapping and examinations of LROC imagery in regions antipodal to young large impact basins</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hood, Lon L.; Richmond, Nicola C.; Spudis, Paul D.</p> <p>2013-06-01</p> <p>The existence of <span class="hlt">magnetization</span> signatures and landform modification antipodal to young lunar impact basins is investigated further by (a) producing more detailed regional crustal <span class="hlt">magnetic</span> field maps at low altitudes using Lunar Prospector magnetometer data; and (b) examining Lunar Reconnaissance Orbiter Wide Angle Camera imagery. Of the eight youngest lunar basins, five are found to have concentrations of relatively strong <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> centered within 10° of their antipodes. This includes the polar Schrödinger basin, which is one of the three youngest basins and has not previously been investigated in this context. Unusual terrain is also extensively present near the antipodes of the two largest basins (Orientale and Imbrium) while less pronounced manifestations of this terrain may be present near the antipodes of Serenitatis and Schrödinger. The area near the Imbrium antipode is characterized by enhanced surface thorium abundances, which may be a consequence of antipodal deposition of ejecta from Imbrium. The remaining three basins either have antipodal regions that have been heavily modified by later events (Hertzsprung and Bailly) or are not clearly recognized to be a true basin (Sikorsky-Rittenhouse). The most probable source of the Descartes <span class="hlt">anomaly</span>, which is the strongest isolated <span class="hlt">magnetic</span> <span class="hlt">anomaly</span>, is the hilly and furrowed Descartes terrain near the Apollo 16 landing site, which has been inferred to consist of basin ejecta, probably from Imbrium according to one recent sample study. A model for the origin of both the modified landforms and the <span class="hlt">magnetization</span> signatures near lunar basin antipodes involving shock effects of converging ejecta impacts is discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70024730','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70024730"><span id="translatedtitle">A source-depth separation filter: Using the Euler method on the derivatives of total intensity <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> data</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Ravat, D.; Kirkham, K.; Hildenbrand, T.G.</p> <p>2002-01-01</p> <p>An overview is given on the benefits of applying the Euler method on derivatives of <span class="hlt">anomalies</span> to enhance the location of shallow and deep sources. Used properly, the method is suitable for characterizing sources from all potential-field data and/or their derivative, as long as the data can be regarded mathematically as "continuous". Furthermore, the reasons why the use of the Euler method on derivatives of <span class="hlt">anomalies</span> is particularly helpful in the analysis and interpretation of shallow features are explained.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5513432','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5513432"><span id="translatedtitle">Holonomy <span class="hlt">anomalies</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Bagger, J.; Nemeschansky, D.; Yankielowicz, S.</p> <p>1985-05-01</p> <p>A new type of <span class="hlt">anomaly</span> is discussed that afflicts certain non-linear sigma models with fermions. This <span class="hlt">anomaly</span> is similar to the ordinary gauge and gravitational <span class="hlt">anomalies</span> since it reflects a topological obstruction to the reparametrization invariance of the quantum effective action. Nonlinear sigma models are constructed based on homogeneous spaces G/H. <span class="hlt">Anomalies</span> arising when the fermions are chiral are shown to be cancelled sometimes by Chern-Simons terms. Nonlinear sigma models are considered based on general Riemannian manifolds. 9 refs. (LEW)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010cosp...38.4223D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010cosp...38.4223D"><span id="translatedtitle">Space Weather and Satellite <span class="hlt">Anomalies</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dorman, Lev; Iucci, N.; Levitin, A. E.; Belov, A. V.; Eroshenko, E. A.; Ptitsyna, N. G.; Villoresi, G.; Chizhenkov, G. V.; Gromova, L. I.; Parisi, M.; Tyasto, M. I.; Yanke, V. G.</p> <p></p> <p>Results of the Satellite <span class="hlt">Anomaly</span> Project, which aims to improve the methods of safeguarding satellites in the Earth's magnetosphere from the negative effects of the space environment, are presented. <span class="hlt">Anomaly</span> data from the "Kosmos" series satellites in the period 1971-1999 are com-bined in one database, together with similar information on other spacecrafts. This database contains, beyond the <span class="hlt">anomaly</span> information, various characteristics of the space weather: geo-<span class="hlt">magnetic</span> activity indices (Ap, AE and Dst), fluxes and fluencies of electrons and protons at different energies, high energy cosmic ray variations and other solar, interplanetary and solar wind data. A comparative analysis of the distribution of each of these parameters relative to satellite <span class="hlt">anomalies</span> was carried out for the total number of <span class="hlt">anomalies</span> (about 6000 events), and separately for high ( 5000 events) and low (about 800 events) altitude orbit satellites. No relation was found between low and high altitude satellite <span class="hlt">anomalies</span>. Daily numbers of satel-lite <span class="hlt">anomalies</span>, averaged by a superposed epoch method around sudden storm commencements and proton event onsets for high (∼1500 km) and low (¡1500 km) altitude orbits revealed a big difference in a behavior. Satellites were divided on several groups according to the orbital char-acteristics (altitude and inclination). The relation of satellite <span class="hlt">anomalies</span> to the environmental parameters was found to be different for various orbits that should be taken into account under developing of the <span class="hlt">anomaly</span> frequency models. The preliminary <span class="hlt">anomaly</span> frequency models are presented. Keywords: Space weather; Satellite <span class="hlt">anomalies</span>; Energetic particles; <span class="hlt">Magnetic</span> storms</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003EAEJA....12715B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003EAEJA....12715B"><span id="translatedtitle"><span class="hlt">Spreading</span> reorganisation during a major change in relative plate motion</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Blais, A.; Gente, P.; Dyment, J.; Royer, J.-Y.</p> <p>2003-04-01</p> <p>Bathymetry, <span class="hlt">magnetic</span> and gravity data obtained during the Magofond2 cruise (1998), near the Mauritius Island, are used to characterise the <span class="hlt">spreading</span> reorganisation during the major change in the <span class="hlt">spreading</span> rate and the relative plate motion between <span class="hlt">anomalies</span> 22 (50 Myr) and 18 (40 Myr). These changes are due to the progressive collision between the India and the Eurasia plate. Plate tectonic reconstructions of the India and African plates reveal a reorganisation of the first-order segmentation implying death and birth of major fracture zones and variation of their offset. Important asymmetric <span class="hlt">spreading</span> is observed and could be partly explained by a series of propagations. The analysis of fault azimuths reveals a drastic change in abyssal hills direction just before <span class="hlt">anomaly</span> 20o (44 Myr) in the northern part of the study area, and a less abrupt change in the southern part. This age corresponds to the major phase of the collision between India and Eurasia. The decrease of the <span class="hlt">spreading</span> rate induces a rapid change in the seafloor morphology and in the second-order segmentation. Before chron 21y (46 Myr), the oceanic crust presents the characteristics of a fast <span class="hlt">spreading</span> ridge with a smooth bathymetry, small gravity variations and a less apparent segmentation. After chron 21y, the ocean floor presents typical slow <span class="hlt">spreading</span> ridge morphology : oblique deep basins characterise the second order discontinuities, the roughness of the topography increases and Bull-eyes gravity <span class="hlt">anomalies</span> mark the segmentation. This new organisation of the oceanic floor becomes more chaotic after chron 20o, with a series of short segments affected by rapid propagations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009EGUGA..11.8812B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009EGUGA..11.8812B"><span id="translatedtitle">The Gop Basin - A Possible Imprint of Early Oceanic <span class="hlt">Spreading</span> Between Greater Seychelles and India</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bhattacharya, G. C.; Yatheesh, V.; Dyment, J.</p> <p>2009-04-01</p> <p>The Arabian and its conjugate Eastern Somali basins were formed by the seafloor <span class="hlt">spreading</span> at the Carlsberg Ridge since Early Tertiary (<span class="hlt">anomaly</span> 28n; ~62.5 Ma). The reconstruction model at <span class="hlt">anomaly</span> 28n suggested existence of a wide swath of deep offshore region (Gop and Laxmi basins) between the Laxmi Ridge and the India-Pakistan continental shelf. In the present study we focus on the Gop Basin, where the important constraints about the early geodynamic evolution of the Arabian Sea appear to exist. The nature of the crust underlying this basin remains a matter of debate, with views varying from volcanics-intruded thinned continental crust to oceanic crust formed by a now extinct <span class="hlt">spreading</span> centre. Our interpretation of an updated compilation of marine geophysical data supports the oceanic nature of the crust underlying the Gop Basin, where the Palitana Ridge represents the extinct <span class="hlt">spreading</span> centre related to an episode of early oceanic <span class="hlt">spreading</span> between Greater Seychelles (Seychelles-Laxmi Ridge block) and India. Our <span class="hlt">magnetic</span> modelling shows that the well correlatable, prominent but short sequence of <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> in the Gop Basin does not allow a unique identification; it can be reasonably explained either as A31r - A25r (~69 - 56 Ma) or as A29r - A25r (~65 - 56 Ma) sequence. Both the models suggest that <span class="hlt">spreading</span> in the Gop Basin was significantly affected by the nearby onset of the Reunion hotspot at ~65 Ma, which formed the Deccan Traps on the adjacent western Indian mainland.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.T51E2387Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.T51E2387Z"><span id="translatedtitle">Basement and crustal structure from <span class="hlt">magnetic</span> and gravity <span class="hlt">anomalies</span> in the Songpan-Garzê and adjacent areas, China</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, J.; Gao, R.; Li, Q.; Zhang, S.; Guan, Y.; Wang, H.</p> <p>2011-12-01</p> <p>The Songpan-Garzê orogenic belt is located in the eastern part of the Tibetan Plateau and west of the Sichuan basin. It is bounded by the South China, North China, Kunlun-Qaidam and Qiangtang (North Tibet) continental blocks. To the east, the Longmen Shan thrust-nappe belt separates the Songpan-Garzê fold belt from the Sichuan basin. The Songpan-Garzê basin and adjacent area are filled with a thick sequence of Triassic flyschoid sedimentary rocks. Within the Songpan-Garzê area, the Neoproterozoic basement only crops out in the southern part, in the Danba antiformal structure and to the east, along the Longmen-Shan belt, in the Xuelongbao metamorphic complex. To the north, below the Triassic sedimentary rocks, the nature of the basement (oceanic or continental) remains unknown. In order to research the range and the affinity of the basement of Songpan-Garzê orogenic belt, we ascertain the distribution range of the basement of Songpan-Garzê orogenic belt with aeromagnetic and seismic data, and discuss the affinity of the basement of the Songpan-Garzê orogenic belt with the geochemical data. Before identifying the boundaries of the basement we reduced the <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> to pole and continued them upward. The results show that the basement in Songpan-Ganzi areas belongs to Yangzi block. The boundaries are Erdaogou-Yushu-Litang in the west-south, Qingchuan-Dujiangyan in the east, and the line of southern Kunlun to Xinghai-Xiahe-Xihe. Under the restrictions of deep seismic sounding and rock density characteristics, we calculate the density structure of the crust across the Songpan-Garzê orogenic belt and adjacent areas along the gravity profile A-A', which trends 400NE. The density model of the crust in this area is divided into two parts, upper and lower crust, vertically. The depth of the Moho is about 62 km in the southwest, and 54 km in the northeast. This model shows that gravity isostasy obeys the Airy theory approximately within the Songpan-Garzê orogenic belt although a buried load in the bottom of lower crust. While a buried load remain beneath the Moho to the north of Songpan-Garzê orogenic belt. During constructing these buried loads we computed local decompensative gravity <span class="hlt">anomalies</span> on the condition that the depth of the lithospheric bottom is 120km. This work was supported by Crust Probe Project of China (SINOPROBE-02, SINOPROBE-08-02), the Natural Science Foundation of China (Nos. 40830316, 40774026, 40874045 ), China Geological Survey (Nos. 1212010611809, 1212010711813, 1212010811033), and scientific research project for public welfare from the Ministry of Land and Resources of China (No. 200811021,201011042).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1995MarGR..17..361M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1995MarGR..17..361M"><span id="translatedtitle">Asymmetric seafloor <span class="hlt">spreading</span> and short ridge jumps in the Australian-Antarctic discordance</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Marks, Karen M.; Stock, Joann M.</p> <p>1995-08-01</p> <p>The crenulated geometry of the Southeast Indian ridge within the Australian-Antarctic discordance is formed by numerous <span class="hlt">spreading</span> ridge segments that are offset, alternately to the north and south, by transform faults. Suggested causes for these offsets, which largely developed since ~ 20 Ma, include asymmetric seafloor <span class="hlt">spreading</span>, ridge jumps, and propagating rifts that have transferred seafloor from one flank of the <span class="hlt">spreading</span> ridge to the other. Each of these processes has operated at different times in different locations of the discordance; here we document an instance where a small (~ 20 km), young (< 0.2 Ma), southward ridge jump has contributed to the observed asymmetry. When aeromagnetic <span class="hlt">anomalies</span> from the Project Investigator-1 survey are superposed on gravity <span class="hlt">anomalies</span> computed from Geosat GM and ERM data, we find that in segment B4 of the discordance (between 125° and 126° E), the roughly east-west-trending gravity low, correlated with the axial valley, is 20 25 km south of the ridge axis position inferred from the center of <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> 1. Elsewhere in the discordance, the inferred locations of the ridge axis from <span class="hlt">magnetics</span> and gravity are in excellent agreement. Ship track data confirm these observations: portions of Moana Wave track crossing the ridge in B4 show that a topographic valley correlated with the gravity <span class="hlt">anomaly</span> low lies south of the center of <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> 1; while other ship track data that cross the <span class="hlt">spreading</span> ridge in segments B3 and B5 demonstrate good agreement between the axial valley, the gravity <span class="hlt">anomaly</span> low, and the central <span class="hlt">magnetic</span> <span class="hlt">anomaly</span>. Based on these observations, we speculate that the ridge axis in B4 has recently jumped to the south, from a ridge location closer to the center of the young normally <span class="hlt">magnetized</span> crust, to that of the gravity <span class="hlt">anomaly</span> low. The position of the gravity low essentially at the edge of normally <span class="hlt">magnetized</span> crust requires a very recent (< 0.2 Ma) arrival of the ridge in this new location. Because this ridge jump is so young, it may be a promising location for future detailed studies of the dynamics, kinematics, and thermal effects of ridge jumps.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70036520','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70036520"><span id="translatedtitle">M3 spectral analysis of lunar swirls and the link between optical maturation and surface hydroxyl formation at <span class="hlt">magnetic</span> <span class="hlt">anomalies</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Kramer, G.Y.; Besse, S.; Dhingra, D.; Nettles, J.; Klima, R.; Garrick-Bethell, I.; Clark, R.N.; Combe, J.-P.; Head, J. W., III; Taylor, L.A.; Pieters, C.M.; Boardman, J.; McCord, T.B.</p> <p>2011-01-01</p> <p>We examined the lunar swirls using data from the Moon Mineralogy Mapper (M3). The improved spectral and spatial resolution of M3 over previous spectral imaging data facilitates distinction of subtle spectral differences, and provides new information about the nature of these enigmatic features. We characterized spectral features of the swirls, interswirl regions (dark lanes), and surrounding terrain for each of three focus regions: Reiner Gamma, Gerasimovich, and Mare Ingenii. We used Principle Component Analysis to identify spectrally distinct surfaces at each focus region, and characterize the spectral features that distinguish them. We compared spectra from small, recent impact craters with the mature soils into which they penetrated to examine differences in maturation trends on- and off-swirl. Fresh, on-swirl crater spectra are higher albedo, exhibit a wider range in albedos and have well-preserved mafic absorption features compared with fresh off-swirl craters. Albedoand mafic absorptions are still evident in undisturbed, on-swirl surface soils, suggesting the maturation process is retarded. The spectral continuum is more concave compared with off-swirl spectra; a result of the limited spectral reddening being mostly constrained to wavelengths less than ???1500 nm. Off-swirl spectra show very little reddening or change in continuum shape across the entire M3 spectral range. Off-swirl spectra are dark, have attenuated absorption features, and the narrow range in off-swirl albedos suggests off-swirl regions mature rapidly. Spectral parameter maps depicting the relative OH surface abundance for each of our three swirl focus regions were created using the depth of the hydroxyl absorption feature at 2.82 ??m. For each of the studied regions, the 2.82 ??m absorption feature is significantly weaker on-swirl than off-swirl, indicating the swirls are depleted in OH relative to their surroundings. The spectral characteristics of the swirls and adjacent terrains from all three focus regions support the hypothesis that the <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> deflect solar wind ions away from the swirls and onto off-swirl surfaces. Nanophase iron (npFe0) is largely responsible for the spectral characteristics we attribute to space weathering and maturation, and is created by vaporization/deposition by micrometeorite impacts and sputtering/reduction by solar wind ions. On the swirls, the decreased proton flux slows the spectral effects of space weathering (relative to nonswirl regions) by limiting the npFe0 production mechanism almost exclusively to micrometeoroid impact vaporization/deposition. Immediately adjacent to the swirls, maturation is accelerated by the increased flux of protons deflected from the swirls. Copyright 2011 by the American Geophysical Union.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004JAG....56..195M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004JAG....56..195M"><span id="translatedtitle">Earth analog for Martian <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>: remanence properties of hemo-ilmenite norites in the Bjerkreim-Sokndal intrusion, Rogaland, Norway</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>McEnroe, S. A.; Brown, L. L.; Robinson, Peter</p> <p>2004-10-01</p> <p>To explain the very large remanent <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> on Mars, which no longer has a global <span class="hlt">magnetic</span> field, it is important to evaluate rocks on Earth with the necessary properties of high natural remanent <span class="hlt">magnetization</span> (NRM) and coercivity. Here, we describe a possible analog from the 230-km 2 930 Ma Bjerkreim-Sokndal layered intrusion (BKS) in Rogaland, Norway. In the layered series of the BKS, fractional crystallization of jotunitic magma was punctuated by influx and mixing of more primitive magmas, producing six megacyclic units, each typically with early plagioclase-rich norites, intermediate hemo-ilmenite-rich norites and late magnetite norites with subordinate near end-member ilmenite. Following each influx, the magma resumed normal crystallization and, following the last, near the base of Megacyclic Unit IV, crystallization continued until norites gave way to massive fayalite-magnetite mangerites and quartz mangerites in the upper part of the intrusion. The Megacycles are marked on a regional aeromagnetic map by remanent-controlled negative <span class="hlt">anomalies</span> over ilmenite norites and induced positive <span class="hlt">anomalies</span> over magnetite norites and mangerites. A prominent negative <span class="hlt">anomaly</span> (with amplitude -13,000 nT in a high-resolution helicopter survey, down to -27,000 nT below background in ground <span class="hlt">magnetic</span> profiles) occurs over the central part of Megacyclic Unit IV. The <span class="hlt">anomaly</span> is centered on ilmenite norite Unit IVe and is most intense where cumulate layering is near vertical at the southeast edge of the Bjerkreim Lobe of the intrusion at Heskestad. Here, Unit IVe is flanked to the east by magnetite norite of Unit IVc and country-rock gneisses (group E) and to the west by Unit IVf magnetite norite and mangerites (group W). <span class="hlt">Magnetic</span> properties were measured on 128 oriented samples. Susceptibilities are similar for all three sample groups at ˜8×10 -2, but Koenigsberger ratios are very different, with average values of 7.7 for IVe, and <1 for groups E and W. The IVe samples, with only a few percent of oxides, have the highest NRMs measured from the BKS, up to 74 A/m, with an average of 30.6 A/m, making them prime candidates for consideration as Mars analogs. The mean direction for IVe samples is D=17.6°, I=-79.9, a95=10°, almost opposite the present field. Evidence on origin of the strong NRM in IVe as compared to groups E and W, include greater abundance of hemo-ilmenite and of orthopyroxene with hemo-ilmenite exsolution, and the strong lattice-preferred orientation of both in a relationship favorable for "lamellar <span class="hlt">magnetism</span>". Massive magnetite-free hemo-ilmenite ores in anorthosite from the same district also produce negative <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>. They have a substantial but much lower NRM, suggesting that there are special oxide properties in the IVe rocks at Heskestad.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20000110429&hterms=Magnetic+interaction&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DTitle%26N%3D0%26No%3D10%26Ntt%3DMagnetic%2Binteraction','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20000110429&hterms=Magnetic+interaction&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DTitle%26N%3D0%26No%3D10%26Ntt%3DMagnetic%2Binteraction"><span id="translatedtitle">The Effects of <span class="hlt">Magnetic</span> <span class="hlt">Anomalies</span> Discovered at Mars on the Structure of the Martian Ionosphere and the Solar Wind Interaction as Follows from Radio Occultation Experiments</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ness, N. F.; Acuna, M. H.; Connerney, J. E. P.; Cloutier, P.; Kliore, A. J.; Breus, T. K.; Krymskii, A. M.; Bauer, S. J.</p> <p>1999-01-01</p> <p>The electron density distribution in the ionosphere of nonmagnetic (or weakly <span class="hlt">magnetized</span>) planet depends not only on the solar ultraviolet intensity, but also on the nature of the SW interaction with this planet. Two scenarios previously have been developed based on the observations of the bow shock crossings and on the electron density distribution within the ionosphere. According to one of them Mars has an intrinsic magnetosphere produced by a dipole <span class="hlt">magnetic</span> field and the Martian ionosphere is protected from the SW flow except during "overpressure conditions, when the planetary <span class="hlt">magnetic</span> field can not balance the SW dynamic pressure. In the second scenario the Martian intrinsic <span class="hlt">magnetic</span> dipole field is so weak that Mars has mainly an induced magnetosphere and a Venus-like SW/ionosphere interaction. Today the possible existence of a sufficiently strong global <span class="hlt">magnetic</span> field that participates in the SW/Mars interaction can no longer be supported. The results obtained by the Mars-Global-Surveyor (MGS) space-craft show the existence of highly variable, but also very localized <span class="hlt">magnetic</span> fields of crustal origin at Mars as high as 400-1500 nT. The absence of the large-scale global <span class="hlt">magnetic</span> field at Mars makes it similar to Venus, except for possible effects of the <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> associated with the remnant crustal <span class="hlt">magnetization</span>. However the previous results on the Martian ionosphere obtained mainly by the radio occultation methods show that there appears to be a permanent existence of a global horizontal <span class="hlt">magnetic</span> field in the Martian ionosphere. Moreover the global induced <span class="hlt">magnetic</span> field in the Venus ionosphere is not typical at the solar zenith angles explored by the radio occultation methods. Additional information is contained in the original extended abstract.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.genome.gov/14514230','NIH-MEDLINEPLUS'); return false;" href="http://www.genome.gov/14514230"><span id="translatedtitle">Learning about Poland <span class="hlt">Anomaly</span></span></a></p> <p><a target="_blank" href="http://medlineplus.gov/">MedlinePlus</a></p> <p></p> <p></p> <p>... genetic terms used on this page Learning About Poland <span class="hlt">Anomaly</span> What is Poland <span class="hlt">anomaly</span>? What are the ... <span class="hlt">Anomaly</span> Additional Resources for Poland <span class="hlt">Anomaly</span> What is Poland <span class="hlt">anomaly</span>? Named after Sir Alfred Poland, Poland <span class="hlt">anomaly</span> ( ...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMGP23B3675D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMGP23B3675D"><span id="translatedtitle">Untangling Magmatic Processes and Hydrothermal Alteration of in situ Superfast <span class="hlt">Spreading</span> Ocean Crust at ODP/IODP Site 1256 with Fuzzy c-means Cluster Analysis of Rock <span class="hlt">Magnetic</span> Properties</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dekkers, M. J.; Heslop, D.; Herrero-Bervera, E.; Acton, G.; Krasa, D.</p> <p>2014-12-01</p> <p>Ocean Drilling Program (ODP)/Integrated ODP (IODP) Hole 1256D (6.44.1' N, 91.56.1' W) on the Cocos Plate occurs in 15.2 Ma oceanic crust generated by superfast seafloor <span class="hlt">spreading</span>. Presently, it is the only drill hole that has sampled all three oceanic crust layers in a tectonically undisturbed setting. Here we interpret down-hole trends in several rock-<span class="hlt">magnetic</span> parameters with fuzzy c-means cluster analysis, a multivariate statistical technique. The parameters include the <span class="hlt">magnetization</span> ratio, the coercivity ratio, the coercive force, the low-field susceptibility, and the Curie temperature. By their combined, multivariate, analysis the effects of magmatic and hydrothermal processes can be evaluated. The optimal number of clusters - a key point in the analysis because there is no a priori information on this - was determined through a combination of approaches: by calculation of several cluster validity indices, by testing for coherent cluster distributions on non-linear-map plots, and importantly by testing for stability of the cluster solution from all possible starting points. Here, we consider a solution robust if the cluster allocation is independent of the starting configuration. The five-cluster solution appeared to be robust. Three clusters are distinguished in the extrusive segment of the Hole that express increasing hydrothermal alteration of the lavas. The sheeted dike and gabbro portions are characterized by two clusters, both with higher coercivities than in lava samples. Extensive alteration, however, can obliterate <span class="hlt">magnetic</span> property differences between lavas, dikes, and gabbros. The imprint of thermochemical alteration on the iron-titanium oxides is only partially related to the porosity of the rocks. All clusters display rock <span class="hlt">magnetic</span> characteristics in line with a stable NRM. This implies that the entire sampled sequence of ocean crust can contribute to marine <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>. Determination of the absolute paleointensity with thermal techniques is not straightforward because of the propensity of oxyexsolution during laboratory heating and/or the presence of intergrowths. The upper part of the extrusive sequence, the granoblastic portion of the dikes, and moderately altered gabbros may contain a comparatively uncontaminated thermoremanent <span class="hlt">magnetization</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70024689','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70024689"><span id="translatedtitle">The Emerson Lake Body: A link between the Landers and Hector Mine earthquakes, southern California, as inferred from gravity and <span class="hlt">magnetic</span> <span class="hlt">anomalies</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Langenheim, V.E.; Jachens, R.C.</p> <p>2002-01-01</p> <p>Gravity and <span class="hlt">magnetic</span> data indicate a mafic crustal heterogeneity that lies between the Hector Mine 16 October 1999 (Mw 7.1) and Landers 28 June 1992 (Mw 7.3) epicenters. The aftershocks and ruptures of these two events avoided the interior of the body. Two- and three-dimensional modeling of the potential-field <span class="hlt">anomalies</span> shows that the source, here named the Emerson Lake body (ELB), extends to a depth of approximately 15 km. The source of the gravity and <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> is most likely Jurassic diorite because exposures of these rocks coincide with both gravity and <span class="hlt">magnetic</span> highs west of Emerson Lake. Seismic tomography also shows higher velocities within the region of the ELB. We propose that the ELB was an important influence on the rupture geometry of the Landers and Hector Mine ruptures and that the ELB may have played a role in transferring of stress from the Landers earthquake to the Hector Mine hypocenter. Seismicity before the Landers earthquake also tended to avoid the ELB, suggesting that the ELB affects how strain is distributed in this part of the Mojave Desert. Thus, faults within the body should have limited rupture sizes and lower seismic hazard than faults bounding or outside this mafic crustal heterogeneity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JGRB..118.3742Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JGRB..118.3742Z"><span id="translatedtitle">The shallow structure of K?lauea caldera from high-resolution Bouguer gravity and total <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> mapping: Insights into progressive magma reservoir growth</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zurek, Jeffrey; Williams-Jones, Glyn</p> <p>2013-07-01</p> <p>conducted total <span class="hlt">magnetic</span> field and Bouguer gravity measurements to investigate the shallow structure beneath the summit caldera of K?lauea Volcano, Hawai'i. Two significant and distinctive <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> were identified within the caldera. One is interpreted to be associated with a long-lived prehistoric eruptive center, the Observatory vent, located ~1 km east of the Hawaiian Volcano Observatory. The second <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> corresponds to a set of eruptive fissures that strike northeast from Halema'uma'u Crater, suggesting this is an important transport pathway for magma. The Bouguer gravity data were inverted to produce 3-D models of density contrasts in the upper 2 km beneath K?lauea. The models detect 3.0 km3 of material, denser than 2800 kg m-3, beneath the caldera that may represent an intrusive complex centered northeast of Halema'uma'u. Recent temporal gravity studies indicate continual addition of mass beneath the caldera during 1975-2008 centered west of Halema'uma'u and suggest this is due to filling of void space. The growth of a large intrusive complex, apparent cyclical caldera formation, and continual mass addition without inflation, however, can also be explained by extensional rifting caused by the continual southward movement of K?lauea's unstable south flank.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1999EL.....45..361D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1999EL.....45..361D"><span id="translatedtitle">Quantum Hall effect <span class="hlt">anomaly</span> and collective modes in the <span class="hlt">magnetic</span>-field induced spin-density-wave phases of quasi one-dimensional conductors</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dupuis, N.; Yakovenko, V. M.</p> <p>1999-02-01</p> <p>We study the collective modes in the <span class="hlt">magnetic</span>-field induced spin-density-wave (FISDW) phases experimentally observed in organic conductors of the Bechgaard salts family. In phases that exhibit a sign reversal of the quantum Hall effect (Ribault <span class="hlt">anomaly</span>), the coexistence of two spin-density waves gives rise to additional long-wavelength collective modes besides the Goldstone modes due to spontaneous translation and rotation symmetry breaking. These modes strongly affect the charge and spin response functions. We discuss some experimental consequences for the Bechgaard salts.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26323817','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26323817"><span id="translatedtitle"><span class="hlt">Magnetic</span> resonance imaging evidence for perineural <span class="hlt">spread</span> of endometriosis to the lumbosacral plexus: report of 2 cases.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Siquara de Sousa, Ana C; Capek, Stepan; Howe, Benjamin M; Jentoft, Mark E; Amrami, Kimberly K; Spinner, Robert J</p> <p>2015-09-01</p> <p>Sciatic nerve endometriosis (EM) is a rare presentation of retroperitoneal EM. The authors present 2 cases of catamenial sciatica diagnosed as sciatic nerve EM. They propose that both cases can be explained by perineural <span class="hlt">spread</span> of EM from the uterus to the sacral plexus along the pelvic autonomie nerves and then further distally to the sciatic nerve or proximally to the spinal nerves. This explanation is supported by MRI evidence in both cases. As a proof of concept, the authors retrieved and analyzed the original MRI studies of a case reported in the literature and found a similar pattern of <span class="hlt">spread</span>. They believe that the imaging evidence of their institutional cases together with the outside case is a very compelling indication for perineural <span class="hlt">spread</span> as a mechanism of EM of the nerve. PMID:26323817</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26256858','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26256858"><span id="translatedtitle"><span class="hlt">Magnetic</span> <span class="hlt">anomalies</span> and itinerant character of electrochemically Li-inserted Li[Li1/3Ti5/3]O4.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mukai, Kazuhiko; Sugiyama, Jun</p> <p>2015-09-21</p> <p>Spinel oxides of Li[LiyTi2-y]O4 with 0 ≤y≤ 1/3 exhibit two desirable features for solid state chemistry and condensed matter physics. One is a reversible lithium insertion/extraction reaction, in particular for Li[Li1/3Ti5/3]O4, and the other is a superconducting transition at Tc≃ 13 K for Li[Ti2]O4. To study the change in <span class="hlt">magnetic</span> environments of the y = 1/3 compound with excess Li(x), we measured the <span class="hlt">magnetic</span> susceptibility (χ) for the Li1+x[Li1/3Ti5/3]O4 samples with 0 ≤x≤ 0.95, which were prepared by an electrochemical Li insertion reaction into Li[Li1/3Ti5/3]O4. Even for the x = 0 sample, two <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> were found at T (=63 K) and T (=21 K), despite the fact that all Ti ions should be in the 4+ state with S = 0. A comparative study of TiO2 and Li2TiO3 revealed that these <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> are not impurity-induced effects but are caused by an intrinsic nature of Li[Li1/3Ti5/3]O4, probably due to either slight compositional deviation from stoichiometry or dislocations such as a Magnéli phase. For the x > 0 samples, the χ vs. temperature curve was found to consist of a temperature-independent Pauli-paramagnetic contribution and a Curie-Weiss contribution. Detailed analyses of χ clarified the systematic variations of the effective <span class="hlt">magnetic</span> moment of Ti ions, effective mass of electrons in the conduction band, and density of states at the Fermi level with x, indicating that the Li(+) ions at the 16d site play a significant role in localizing d electrons of Ti(3+) ions. PMID:26256858</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19820017716','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19820017716"><span id="translatedtitle">The reduction, verification and interpretation of MAGSAT <span class="hlt">magnetic</span> data over Canada</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Coles, R. L. (Principal Investigator); Haines, G. V.; Vanbeek, G. J.; Walker, J. K.; Newitt, L. R.; Nandi, A.</p> <p>1982-01-01</p> <p>Correlations between the MAGSAT scalar <span class="hlt">anomaly</span> map produced at the Earth Physics ranch and other geophysical and geological data reveal relationships between high <span class="hlt">magnetic</span> field and some metamorphic grade shields, as well as between low <span class="hlt">magnetic</span> field and shield regions of lower metamorphic grade. An intriguing contrast exists between the broad low <span class="hlt">anomaly</span> field over the Nasen-Gakkel Ridge (a <span class="hlt">spreading</span> plate margin) and the high <span class="hlt">anomaly</span> field over Iceland (part of a <span class="hlt">spreading</span> margin). Both regions have high heat flow, and presumably thin <span class="hlt">magnetic</span> crust. This indicates that Iceland is quite anomalous in its <span class="hlt">magnetic</span> character, and possible similarities with the Alpha Ridge are suggested. Interesting correlations exist between MAGSAT <span class="hlt">anomalies</span> around the North Atlantic, after reconstructing the fit of continents into a prerifting configuration. These correlations suggest that several orogenies in that region have not completely destroyed an ancient <span class="hlt">magnetization</span> formed in high grade Precambrian rocks.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.usgs.gov/of/2009/1258/','USGSPUBS'); return false;" href="http://pubs.usgs.gov/of/2009/1258/"><span id="translatedtitle">A Preliminary, Full Spectrum, <span class="hlt">Magnetic</span> <span class="hlt">Anomaly</span> Grid of the United States with Improved Long Wavelengths for Studying Continental Dynamics: A Website for Distribution of Data</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Ravat, D.; Finn, C.; Hill, P.; Kucks, R.; Phillips, J.; Blakely, R.; Bouligand, C.; Sabaka, T.; Elshayat, A.; Aref, A.; Elawadi, E.</p> <p>2009-01-01</p> <p>Under an initiative started by Thomas G. Hildenbrand of the U.S. Geological Survey, we have improved the long-wavelength (50-2,500 km) content of the regional <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> compilation for the conterminous United States by utilizing a nearly homogeneous set of National Uranium Resource Evaluation (NURE) <span class="hlt">magnetic</span> surveys flown from 1975 to 1981. The surveys were flown in quadrangles of 2 deg of longitude by 1 deg of latitude with east-west flight lines spaced 4.8 to 9.6 km apart, north-south tie lines variably spaced, and a nominal terrain clearance of 122 m. Many of the surveys used base-station magnetometers to remove external field variations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/21797593','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/21797593"><span id="translatedtitle">Gravitational <span class="hlt">anomaly</span> and transport phenomena.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Landsteiner, Karl; Megías, Eugenio; Pena-Benitez, Francisco</p> <p>2011-07-01</p> <p>Quantum <span class="hlt">anomalies</span> give rise to new transport phenomena. In particular, a <span class="hlt">magnetic</span> field can induce an anomalous current via the chiral <span class="hlt">magnetic</span> effect and a vortex in the relativistic fluid can also induce a current via the chiral vortical effect. The related transport coefficients can be calculated via Kubo formulas. We evaluate the Kubo formula for the anomalous vortical conductivity at weak coupling and show that it receives contributions proportional to the gravitational <span class="hlt">anomaly</span> coefficient. The gravitational <span class="hlt">anomaly</span> gives rise to an anomalous vortical effect even for an uncharged fluid. PMID:21797593</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EP%26S...67...10K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EP%26S...67...10K"><span id="translatedtitle">Does the South Atlantic <span class="hlt">Anomaly</span> influence the ionospheric Sq current system? Inferences from analysis of ground-based <span class="hlt">magnetic</span> data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Koch, Stephan; Kuvshinov, Alexey</p> <p>2015-12-01</p> <p>We study if and how the South Atlantic <span class="hlt">Anomaly</span> influences the ionospheric solar quiet (Sq) current system. Geomagnetically quiet days are processed for the years 1990 and 2011, and the Sq foci tracks are analyzed. The two datasets allow to investigate the influence of the observatory network and the solar activity on the Sq source determination. The computed tracks result in pronounced bands in the northern and southern hemisphere, which seem to neither follow the geographic nor the geomagnetic or dip equator. Remarkably, we observe a distinct scattering of the tracks over the South Atlantic <span class="hlt">Anomaly</span>. This systematic scattering is due to a larger shift of the southern hemisphere focus northwards during the northern summer solstice and southwards during the southern summer solstice. The physical mechanism of this systematic effect remains unclear. The longitudinal variations of the Sq foci are believed to have their origin from an influence of non-migrating tides as reported in recent studies and the anomalous weak amplitude of the geomagnetic main field over the South Atlantic <span class="hlt">Anomaly</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20040034236','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20040034236"><span id="translatedtitle">Reliability of CHAMP <span class="hlt">Anomaly</span> Continuations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>vonFrese, Ralph R. B.; Kim, Hyung Rae; Taylor, Patrick T.; Asgharzadeh, Mohammad F.</p> <p>2003-01-01</p> <p>CHAMP is recording state-of-the-art <span class="hlt">magnetic</span> and gravity field observations at altitudes ranging over roughly 300 - 550 km. However, <span class="hlt">anomaly</span> continuation is severely limited by the non-uniqueness of the process and satellite <span class="hlt">anomaly</span> errors. Indeed, our numerical <span class="hlt">anomaly</span> simulations from satellite to airborne altitudes show that effective downward continuations of the CHAMP data are restricted to within approximately 50 km of the observation altitudes while upward continuations can be effective over a somewhat larger altitude range. The great unreliability of downward continuation requires that the satellite geopotential observations must be analyzed at satellite altitudes if the <span class="hlt">anomaly</span> details are to be exploited most fully. Given current <span class="hlt">anomaly</span> error levels, joint inversion of satellite and near- surface <span class="hlt">anomalies</span> is the best approach for implementing satellite geopotential observations for subsurface studies. We demonstrate the power of this approach using a crustal model constrained by joint inversions of near-surface and satellite <span class="hlt">magnetic</span> and gravity observations for Maude Rise, Antarctica, in the southwestern Indian Ocean. Our modeling suggests that the dominant satellite altitude <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> are produced by crustal thickness variations and remanent <span class="hlt">magnetization</span> of the normal polarity Cretaceous Quiet Zone.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JPhD...46i5001S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JPhD...46i5001S"><span id="translatedtitle">Origin of <span class="hlt">anomalies</span> and phase competitions around <span class="hlt">magnetic</span> transition temperature in Pr0.7Ca0.3MnO3</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shah, Matiullah; Nadeem, M.; Atif, M.</p> <p>2013-03-01</p> <p>A polycrystalline sample of Pr0.7Ca0.3MnO3 is synthesized by the conventional solid-state reaction method and the phase formation is confirmed by x-ray diffraction. In this work, we addressed the phase competition issues in the vicinity of <span class="hlt">magnetic</span> transition temperature and also established its correlation with oxygen contents of domains, disorder effects and heterogeneity in the material. The appearance and disappearance of <span class="hlt">anomaly</span> in the vicinity of TC (128 K) with <span class="hlt">magnetic</span> field is discussed in terms of establishment of short- and long-range networks between Mn3+ and Mn4+. Switching behaviour of two competing phases is analysed qualitatively and quantitatively, using an equivalent circuit model and <span class="hlt">magnetization</span> analysis. The issue of coexisting phases is further substantiated using a simple depression angle approach of impedance plane plots. variable range hopping is found to be a better model than polaronic for explaining the transport properties of both competing phases below the <span class="hlt">magnetic</span> transition temperature, 128 K.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001AGUFM.T12C0933S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001AGUFM.T12C0933S"><span id="translatedtitle"><span class="hlt">Spreading</span> History of a Segment of the Southern Mid-Atlantic Ridge</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stock, J. M.; Clayton, R. W.</p> <p>2001-12-01</p> <p>The Falkland-Agulhas fracture zone in the South Atlantic Ocean separates crust that records the entire Cenozoic history of South America-Africa <span class="hlt">spreading</span> (on the north) from crust on the south that experienced a more complicated plate motion history including major ridge jumps, an additional plate (Malvinas), and plate reorganizations in early Cenozoic time. The Nathaniel B. Palmer cruise 01-02 in April 2001 measured gravity, <span class="hlt">magnetics</span>, and swath bathymetry on a transit from Cape Town to Punta Arenas, including a survey line in Cenozoic crust on the north side of, and parallel to, the Falkland-Agulhas fracture zone. The objectives were to test previous models of Cenozoic plate motions for this region, and to examine the structure of the Falkland-Agulhas fracture zone by collection of limited single-channel seismic data. From 5° W to 3° W longitude, several seismic lines with accompanying SeaBeam data across the northern flank of the fracture zone reveal it to be a wide zone characterized by multiple parallel southward-facing fault scarps whose strike is 70-80° E of N. From chron 12 time to chron 6 time, the <span class="hlt">spreading</span> history for this segment of the ridge was relatively simple, with slightly asymmetric <span class="hlt">spreading</span> rates (more crust accreted to South America than to Africa), as has been previously noted for this part of the southern Mid-Atlantic Ridge. Between chron 5c and chron 2a, the <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> are complex and disrupted, suggesting possible small-scale ridge jumps and continued asymmetric <span class="hlt">spreading</span>. The modern ridge axis is 40 km east of the topographic high ("ridge crest"). The zones of disrupted <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> may be due to the effects of pseudofault traces in the same <span class="hlt">spreading</span> corridor, visible in satellite gravity data in younger seafloor north of the transit. We recorded late Cretaceous and younger <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> (chrons 34y to 18) on the Africa plate to improve the distribution of known <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> locations in this part of the South Atlantic. The observations are in excellent agreement with previous plate rotation models for Africa-South America motion (e.g. Cande et al. 1988) and conjugate <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> positions from the South America plate. Members of the NBP0102 science party: H. Ai, J. Clinton, R. Decesari, A. Jacobs, M. Kumar, B. Lane, J. Parra, B. Smith, N. Villaume, Z. Yan. >http://www.gps.caltech.edu/ ~jstock/Ge211.html</a></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=CYTOLOGY&id=ED018056','ERIC'); return false;" href="http://eric.ed.gov/?q=CYTOLOGY&id=ED018056"><span id="translatedtitle">DOWN'S <span class="hlt">ANOMALY</span>.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>PENROSE, L.S.; SMITH, G.F.</p> <p></p> <p>BOTH CLINICAL AND PATHOLOGICAL ASPECTS AND MATHEMATICAL ELABORATIONS OF DOWN'S <span class="hlt">ANOMALY</span>, KNOWN ALSO AS MONGOLISM, ARE PRESENTED IN THIS REFERENCE MANUAL FOR PROFESSIONAL PERSONNEL. INFORMATION PROVIDED CONCERNS (1) HISTORICAL STUDIES, (2) PHYSICAL SIGNS, (3) BONES AND MUSCLES, (4) MENTAL DEVELOPMENT, (5) DERMATOGLYPHS, (6) HEMATOLOGY, (7)</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=cytology&id=ED018056','ERIC'); return false;" href="http://eric.ed.gov/?q=cytology&id=ED018056"><span id="translatedtitle">DOWN'S <span class="hlt">ANOMALY</span>.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>PENROSE, L.S.; SMITH, G.F.</p> <p></p> <p>BOTH CLINICAL AND PATHOLOGICAL ASPECTS AND MATHEMATICAL ELABORATIONS OF DOWN'S <span class="hlt">ANOMALY</span>, KNOWN ALSO AS MONGOLISM, ARE PRESENTED IN THIS REFERENCE MANUAL FOR PROFESSIONAL PERSONNEL. INFORMATION PROVIDED CONCERNS (1) HISTORICAL STUDIES, (2) PHYSICAL SIGNS, (3) BONES AND MUSCLES, (4) MENTAL DEVELOPMENT, (5) DERMATOGLYPHS, (6) HEMATOLOGY, (7)…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.T41C2603W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.T41C2603W"><span id="translatedtitle">Seafloor <span class="hlt">spreading</span> and microcontinent formation during Mesozoic breakup between Australia and Greater India</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Williams, S.; Whittaker, J.; Müller, R.</p> <p>2012-12-01</p> <p>The Perth Abyssal Plain (PAP) formed at the nexus of rifting and breakup between three major continents within Gondwana - India, Australia and Antarctica. Oceanic crust within the PAP records the history of Mesozoic seafloor <span class="hlt">spreading</span> as India moved away from Australia. However, despite the clear importance of the seafloor <span class="hlt">spreading</span> history of the PAP in constraining the relative motions of these continents during the early stages of breakup, little attention has been paid to the PAP, and particularly its western flank largely due to a lack of new data in collected in this region. We present new observations to constrain the evolution of the PAP, collected during voyage ss2011/v06 of the Southern Surveyor in late 2011. The new data comprise <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> profile data, swath bathymetry, and dredge samples collected from 7 sites. The most significant dredge results were obtained from the Batavia Knoll (BK) and Gulden Draak Knoll (GDK), two prominent bathymetric features located >1000 km west of the Australian continental margin. Previous tectonic reconstructions typically treat these bathymetric features as igneous plateaus emplaced on older oceanic crust. However, dredges carried out on the western flanks of each of these knolls recovered continental basement rocks, revealing that both knolls are continental fragments. Estimates of the depths to <span class="hlt">magnetic</span> sources for shiptrack profiles across the knolls provide evidence for variations in sediment thickness within the knolls. We use forward modeling of shiptrack <span class="hlt">magnetic</span> profiles combined with gravity <span class="hlt">anomalies</span> derived from satellite altimetry to make first-order estimates of the extent and spatial variation in thickness of the continental crust. New <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> profiles provide evidence for previously unidentified M-series <span class="hlt">anomalies</span> in the western part of the Perth Abyssal Plain, east of the BK and GDK. These observations both support a reconstruction model in which the microcontinents rifted away from Australia as part of greater India during initial breakup at ~130 Ma. Seafloor <span class="hlt">spreading</span> in the PAP continued during the early part of the Cretaceous Normal Superchron (until approximately 108 Ma assuming a constant <span class="hlt">spreading</span> rate inferred from the M-series <span class="hlt">anomalies</span>). A westward jump in the Australia-India plate boundary led to cessation of <span class="hlt">spreading</span> in the PAP and the rifting of the BK and GDK from Greater India. Satellite-derived gravity <span class="hlt">anomalies</span> and swath bathymetry profiles provide evidence for ridge propagation events within the PAP ocean crust, occurring during the Cretaceous Normal Superchron. This series of westwards jumps of the India-Australia plate boundary suggests a strong influence of the Kerguelen hotspot, located beneath eastern greater India at this time.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20050170609&hterms=flexoelectric&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dflexoelectric','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20050170609&hterms=flexoelectric&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dflexoelectric"><span id="translatedtitle">Antipodal <span class="hlt">Magnetic</span> <span class="hlt">Anomalies</span> on the Moon, Contributions from Impact Induced Currents Due to Positive Holes and Flexoelectric Phenomina and Dynamo</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kletetschka, G.; Freund, F.; Wasilewski, P. J.; Mikula, V.; Kohout, Tomas</p> <p>2005-01-01</p> <p>Large impacts on the Moon generate large pressure pulses that penetrate the whole body. Several of these large impacts may have generated antipodal structure with anomalous <span class="hlt">magnetic</span> intensity.These regions can be more than a thousand km across, with fields of the order of tens to hundreds of nT. This is the case of Orientale, Imbrium, Serenitatis, Crisium, and Nectaris impact basins. The production of large-scale <span class="hlt">magnetic</span> fields and associated crustal <span class="hlt">magnetization</span> due to lunar basin-forming impacts was hypothesized to have an origin in fields external to the impact plasma cloud that are produced by the magnetohydrodynamic interaction of the cloud with ambient <span class="hlt">magnetic</span> fields and plasmas. During the period of compressed antipodal field amplification, seismic compressional waves from the impact converge at the antipode resulting in transient shock pressures that reach 2 GPa (20 kbar). This can produce conditions for shock <span class="hlt">magnetic</span> acquisition of the crust antipodal to impact basins.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4177725','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4177725"><span id="translatedtitle">Extravasation into brain and subsequent <span class="hlt">spread</span> beyond the ischemic core of a <span class="hlt">magnetic</span> resonance contrast agent following a step-down infusion protocol in acute cerebral ischemia</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p></p> <p>2014-01-01</p> <p>Background Limiting expansion of the ischemic core lesion by reinstating blood flow and protecting the penumbral cells is a priority in acute stroke treatment. However, at present, methods are not available for effective drug delivery to the ischemic penumbra. To address these issues this study compared the extravasation and subsequent interstitial <span class="hlt">spread</span> of a <span class="hlt">magnetic</span> resonance contrast agent (MRCA) beyond the ischemic core into the surrounding brain in a rat model of ischemia-reperfusion for bolus injection and step-down infusion (SDI) protocols. Methods Male Wistar rats underwent middle cerebral artery (MCA) occlusion for 3 h followed by reperfusion. Perfusion-diffusion mismatched regions indicating the extent of <span class="hlt">spread</span> were identified by measuring cerebral blood flow (CBF) deficits by arterial spin-labeled <span class="hlt">magnetic</span> resonance imaging and the extent of the ischemic core by mapping the apparent diffusion coefficient (ADC) of water with diffusion-weighted imaging. Vascular injury was assessed via MRCA, gadolinium-diethylenetriaminepentaacetic acid (Gd-DTPA) penetration, by Look-Locker T1-weighted MR imaging after either a bolus injection (n = 8) or SDI (n = 6). Spatial and temporal expansion of the MRCA front during a 25 min imaging period was measured from images obtained at 2.5 min intervals. Results The mean ADC lesion was 20 ± 7% of the hemispheric area whereas the CBF deficit area was 60 ± 16%, with the difference between the areas suggesting the possible presence of a penumbra. The bolus injection led to MRCA enhancement with an area that initially <span class="hlt">spread</span> into the ischemic core and then diminished over time. The SDI produced a gradual increase in the area of MRCA enhancement that slowly enlarged to occupy the core, eventually expanded beyond it into the surrounding tissue and then plateaued. The integrated area from SDI extravasation was significantly larger than that for the bolus (p = 0.03). The total number of pixels covered by the SDI at its maximum was significantly larger than the pixels covered by bolus maximum (p = 0.05). Conclusions These results demonstrate that the SDI protocol resulted in a <span class="hlt">spread</span> of the MRCA beyond the ischemic core. Whether plasma-borne acute stroke therapeutics can be delivered to the ischemic penumbra in a similar way needs to be investigated. PMID:25276343</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JSG....70..190L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JSG....70..190L"><span id="translatedtitle">Crustal large-scale serpentinized mantle peridotite body in the Sulu ultrahigh-pressure metamorphic belt, eastern China: Evidence from gravity and <span class="hlt">magnetic</span> <span class="hlt">anomalies</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, Qingsheng; Qiu, Ning; Zheng, Jianping; Li, Zhiyong; Wang, Hongcai</p> <p>2015-01-01</p> <p>From analysis of the geological and geophysical data (gravity, <span class="hlt">magnetic</span>, seismic and petrophysics), we propose that geophysical <span class="hlt">anomalies</span> are produced by a serpentinized mantle peridotite body (SMPB) situated in the middle to lower crust in the Sulu Belt. The SMPB was formed by crustal emplacement of mantle peridotites accompanied by ultrahigh-pressure (UHP) metamorphism. Our finding suggests an emplacement mechanism for the serpentinized mantle wedge (SMW), early in the subduction process. This is different from the classic view, which holds that the serpentinized forearc mantle is formed by in situ hydration processes (Blakely et al., 2005). The petrophysical properties of the SMPB are similar to those of the serpentinized forearc mantle or SMW in modern subduction-zones worldwide, but the formation mechanisms for SMPB and SMW are different. This observation is important for understanding the geodynamic processes that operated in the large UHP metamorphic belt in the Dabie-Sulu area, eastern China.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.T33A2380M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.T33A2380M"><span id="translatedtitle">Gravity and <span class="hlt">Magnetic</span> <span class="hlt">Anomaly</span> Interpretations and 2.5D Cross-Section Models over the Border Ranges Fault System and Aleutian Subduction Zone, Alaska</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mankhemthong, N.; Doser, D. I.; Baker, M. R.; Kaip, G.; Jones, S.; Eslick, B. E.; Budhathoki, P.</p> <p>2011-12-01</p> <p>Quaternary glacial covers and lack of dense geophysical data on the Kenai Peninsula cause a location and geometry of the Border Ranges fault system (BRFS) within a recent forearc-accretionary boundary of Aleutian subduction zone in southern Alaska are unclear. Using new ~1,300 gravity collections within the Anchorage and Kenai Peninsula regions complied with prior 1997 gravity and aeromagnetic data help us better imaging these fault and the subduction structures. Cook Inlet forearc basin is corresponded by deep gravity <span class="hlt">anomaly</span> lows; basin boundaries are characterized by a strong gravity gradient, where are considered to be traces of Border Ranges fault system on the east and Castle Mountain and Bruin Bay fault system on the west and northwest of the forearc basin respectively. Gravity <span class="hlt">anomaly</span> highs over accreted rocks generally increase southeastward to the Aleutian trench, but show a gravity depression over the Kenai Mountains region. The lineament between gravity high and low in the same terrenes over the Kenai Peninsula is may be another evidence to determine the Southern Edge of the Yakutat Microplate (SEY) as inferred by Eberhart-Phillips et al. (2006). Our 2.5-D models illustrate the main fault of the BRFS dips steeply toward the west with a downslip displacement. Gravity and <span class="hlt">Magnetic</span> <span class="hlt">anomaly</span> highs, on the east of the BRFS, probably present a slice of the ultramafic complex emplaced by faults along the boundary of the forearc basin and accretionary wedge terranes. Another <span class="hlt">magnetic</span> high beneath the basin in the southern forearc basin support a serpentiznied body inferred by Saltus et al. (2001), with a decreasing size toward the north. Regional density-gravity models show the Pacific subducting slab beneath the foreacre-arc teranes with a gentle and flatted dip where the subducting plate is located in north of SEY and dips more steeply where it is located on the south of SEY. The gravity depression over the accreted terrene can be explained by a density low slab beneath, which does not exist on the south. Results of 2.5-D density models will be used to guide the building of 3-D inversion models. Plausible interpretations of a modeling structure by implementing a 3-D model will be compared, and the most reasonable model will be used for structures representative of the BRFS including the subduction tectonics in southern Alaska.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JKPS...62...59K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JKPS...62...59K"><span id="translatedtitle">Parametric study of a variable-<span class="hlt">magnetic</span>-field-based energy-selection system for generating a <span class="hlt">spread</span>-out Bragg peak with a laser-accelerated proton beam</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kim, Dae-Hyun; Suh, Tae-Suk; Kang, Young Nam; Yoo, Seung Hoon; Pae, Ki-Hong; Shin, Dongho; Lee, Se Byeong</p> <p>2013-01-01</p> <p>Laser-based proton beam acceleration, which produces broad energy spectra, is unsuitable for direct clinical use. Thus, employing an energy selection system is necessary. The purpose of the present study was to investigate a method whereby a variable <span class="hlt">magnetic</span> field could be employed with an energy selection system to generate a <span class="hlt">spread</span>-out Bragg peak (SOBP). For energy selection, particle transport and dosimetric property measurements, the Geant4 toolkit was implemented. The energy spectrum of the laser-accelerated proton beam was acquired using a particle-in-cell simulation. The hole size and the position of the energy selection collimator were varied in order to determine the effects of those parameters on the dosimetric properties. To generate an SOBP, we changed the <span class="hlt">magnetic</span> field in the energy selection system for each beam weighting factor during beam irradiation. The overall results of this study suggest that the use of an energy selection system with a variable <span class="hlt">magnetic</span> field can effectively generate an SOBP suitable for proton radiation therapy applications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/1158454','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/1158454"><span id="translatedtitle">The Wallula fault and tectonic framework of south-central Washington, as interpreted from <span class="hlt">magnetic</span> and gravity <span class="hlt">anomalies</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Blakely, Richard J.; Sherrod, Brian; Weaver, Craig; Wells, Ray E.; Rohay, Alan C.</p> <p>2013-11-13</p> <p><span class="hlt">Magnetic</span> and gravity data, collected in south-central Washington near the Yakima Fold and Thrust Belt (YFTB) are used to model upper crustal structure, the extent of the late Columbia River Basalt flow named the Ice Harbor member, the vertical conduits (dikes) that the Ice Harbor erupted from, and whether the dikes are offset or affected by faulting on the Wallula Fault zone.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JGRA..121..719P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JGRA..121..719P"><span id="translatedtitle">foF2 long-term trend linked to Earth's <span class="hlt">magnetic</span> field secular variation at a station under the northern crest of the equatorial ionization <span class="hlt">anomaly</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pham Thi Thu, Hong; Amory-Mazaudier, Christine; Le Huy, Minh; Elias, Ana G.</p> <p>2016-01-01</p> <p>Long-term trend of the critical frequency of the F2 ionospheric region, foF2, at Phu Thuy station (21.03°N, 105.96°E), Vietnam, located under the northern crest of the equatorial ionization <span class="hlt">anomaly</span>, EIA, is studied. Annual mean data are analyzed at 04 LT and 12 LT for the period 1962-2002 using monthly median values and monthly mean values during <span class="hlt">magnetically</span> quiet days (am < 20). In both cases we obtain similar trends at 4 LT and 12 LT, which we interpret as an absence of geomagnetic activity effect over trends. The positive trends obtained are not consistent with the negative values expected from greenhouse gases effect at this layer of the upper atmosphere. The increasing trend observed at 12 LT is qualitatively in agreement with the expected effect of the secular displacement of the dip equator over the EIA latitudinal profile. At 04 LT, when the EIA is absent, the positive trend is in qualitative agreement with the secular variation of the Earth's <span class="hlt">magnetic</span> field inclination, I, and the consequent increase of the sin(I)cos(I) factor at the corresponding location.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140011291','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140011291"><span id="translatedtitle">Interpretation of CHAMP <span class="hlt">Magnetic</span> <span class="hlt">Anomaly</span> Data over the Pannonian Basin Region Using Lower Altitude Horizontal Gradient Data</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Taylor, P. T.; Kis, K. I.; Wittmann, G.</p> <p>2013-01-01</p> <p>The ESA SWARM mission will have three earth orbiting magnetometer bearing satellites one in a high orbit and two side-by-side in lower orbits. These latter satellites will record a horizontal <span class="hlt">magnetic</span> gradient. In order to determine how we can use these gradient measurements for interpretation of large geologic units we used ten years of CHAMP data to compute a horizontal gradient map over a section of southeastern Europe with our goal to interpret these data over the Pannonian Basin of Hungary.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70020815','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70020815"><span id="translatedtitle">Phanerozoic stratigraphy of Northwind Ridge, <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> in the Canada Basin, and the geometry and timing of rifting in the Amerasia Basin, Arctic Ocean</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Grantz, A.; Clark, D.L.; Phillips, R.L.; Srivastava, S.P.; Blome, C.D.; Gray, L.-B.; Haga, H.; Mamet, B.L.; McIntyre, D.J.; McNeil, D.H.; Mickey, M.B.; Mullen, M.W.; Murchey, B.I.; Ross, C.A.; Stevens, C.H.; Silberling, Norman J.; Wall, J.H.; Willard, D.A.</p> <p>1998-01-01</p> <p>Cores from Northwind Ridge, a high-standing continental fragment in the Chukchi borderland of the oceanic Amerasia basin, Arctic Ocean, contain representatives of every Phanerozoic system except the Silurian and Devonian systems. Cambrian and Ordovician shallow-water marine carbonates in Northwind Ridge are similar to basement rocks beneath the Sverdrup basin of the Canadian Arctic Archipelago. Upper Mississippian(?) to Permian shelf carbonate and spicularite and Triassic turbidite and shelf lutite resemble coeval strata in the Sverdrup basin and the western Arctic Alaska basin (Hanna trough). These resemblances indicate that Triassic and older strata in southern Northwind Ridge were attached to both Arctic Canada and Arctic Alaska prior to the rifting that created the Amerasia basin. Late Jurassic marine lutite in Northwind Ridge was structurally isolated from coeval strata in the Sverdrup and Arctic Alaska basins by rift shoulder and grabens, and is interpreted to be a riftogenic deposit. This lutite may be the oldest deposit in the Canada basin. A cape of late Cenomanian or Turonian rhyodacite air-fall ash that lacks terrigenous material shows that Northwind Ridge was structurally isolated from the adjacent continental margins by earliest Late Cretaceous time. Closing Amerasia basin by conjoining seafloor <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> beneath the Canada basin or by uniting the pre-Jurassic strata of Northwind Ridge with kindred sections in the Sverdrup basin and Hanna trough yield simular tectonic reconstructions. Together with the orientation and age of rift-marine structures, these data suggest that: 1) prior to opening of the Amerasia basin, both northern Alaska and continental ridges of the Chukchi borderland were part of North America, 2) the extension that created the Amerasia basin formed rift-margin graben beginning in Early Jurassic time and new oceanic crust probably beginning in Late Jurassic or early Neocomian time. Reconstruction of the Amerasia basin on the basis of the stratigraphy of Northwind Ridge and sea-floor <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> in the Canada basin accounts in a general way for the major crustal elements of the Americasia basin, including the highstanding ridges of the Chukchi borderland, and supports S.W. Carye's hypothesis that the Amerasia basin is the product of anticlockwise rotational rifting of Arctic Alaska from North America.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFM.V21A2315B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.V21A2315B"><span id="translatedtitle">Interaction between the nascent Reunion hotspot and the dying Mascarene <span class="hlt">spreading</span> centre</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bissessur, P. D.; Dyment, J.; Deplus, C.; Patriat, P.</p> <p>2010-12-01</p> <p>The Reunion hotspot is one of the best examples of a classical mantle plume which reached the lithosphere and formed continental flood basalt, the Deccan trapps, around 65 Ma, and then made an almost continuous trail as the Indian and African plates moved northward, building the Laccadives, Maldives, and Chagos Ridges between 60 Ma and 35 Ma on the fast Indian plate, then the Nazareth Bank after 35 Ma, Mauritius Island between 10 Ma and 8 Ma, and La Reunion Island since 2 Ma on the slower African plate (e.g. Duncan, 1988). Conversely, the Mascarene Basin is characterized by conjugate <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> 34 to 27 separated by an extinct <span class="hlt">spreading</span> centre. Seafloor <span class="hlt">spreading</span> was therefore active between about 85 Ma, when Africa (including Madagascar) and India (including Seychelles) separated, up to 59 Ma, when the Carlsberg Ridge was fully open between Africa (including Madagascar and Seychelles) and India. The coincidence between the inception of the Reunion hotspot in the Indian lithosphere and the transfer of seafloor <span class="hlt">spreading</span> from the Mascarene basin to the Carlsberg Ridge suggests that the latter is a consequence of the former. Recent cruises, including cruise Forever of R/V L’Atalante in 2006, have focused on the south-eastern part of the basin, around Reunion Island. Swath bathymetric data and dredges have revealed that the five gravity undulations located south of Reunion Island toward the fossil ridge are volcanic ridges lying on oceanic lithosphere dated 68-64 Ma by <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> 30 and 29. The satellite gravity data reveal possible other similar undulations further south, on the north-eastern flank of a fossil <span class="hlt">spreading</span> centre dated by <span class="hlt">anomaly</span> 28 (64-62 Ma). Conversely, no such undulation is observed on the intermediate area, where a more recent fossil <span class="hlt">spreading</span> centre is dated by <span class="hlt">anomaly</span> 27 (62-60 Ma). If validated by future swath bathymetric data, this observation means that the volcanic ridges were built before <span class="hlt">anomaly</span> 27, possibly between 65 Ma (the inception of the Reunion hotspot) and 62 Ma. A closer look to the satellite gravity <span class="hlt">anomaly</span> map reveals that the flanks of the whole Mascarene fossil <span class="hlt">spreading</span> centre exhibit various features. Their distribution is however systematically asymmetric, with most of the larger and elongated features located on the eastern, Indian flank. Some of these elongated features are roughly parallel to the volcanic ridges surveyed south of Reunion Island, lie on oceanic lithosphere of the same age, and seem to abut the fossil axis. We propose that these structures are similar volcanic ridges and therefore that the Reunion hotspot interacted with most of the Mascarene <span class="hlt">spreading</span> centre at the paroxysm of its activity, when it formed the Deccan trap. When the hotspot reduced its activity, the new Carlsberg Ridge opened in its closer vicinity. However, the connection between this new <span class="hlt">spreading</span> centre and the Central Indian Ridge could not be established before <span class="hlt">anomaly</span> 26r (~60 Ma), and seafloor <span class="hlt">spreading</span> continued at a decreasing rate up to this time on the southernmost part of the Mascarene <span class="hlt">spreading</span> centre.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JGRA..12010883H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JGRA..12010883H"><span id="translatedtitle">Concurrent observations at the <span class="hlt">magnetic</span> equator of small-scale irregularities and large-scale depletions associated with equatorial <span class="hlt">spread</span> F</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hickey, Dustin A.; Martinis, Carlos R.; Rodrigues, Fabiano S.; Varney, Roger H.; Milla, Marco A.; Nicolls, Michael J.; Strømme, Anja; Arratia, Juan F.</p> <p>2015-12-01</p> <p>In 2014 an all-sky imager (ASI) and an Advanced Modular Incoherent Scatter Radar consisting of 14 panels (AMISR-14) system were installed at the Jicamarca Radio Observatory. The ASI measures airglow depletions associated with large-scale equatorial <span class="hlt">spread</span> F irregularities (10-500 km), while AMISR-14 detects small-scale irregularities (0.34 m). This study presents simultaneous observations of equatorial <span class="hlt">spread</span> F (ESF) irregularities at 50-200 km scale sizes using the all-sky imager, at 3 m scale sizes using the JULIA (Jicamarca Unattended Long-term Investigations of the Ionosphere and Atmosphere) radar, and at 0.34 m scales using the AMISR-14 radar. We compare data from the three instruments on the night of 20-21 August 2014 by locating the radar scattering volume in the optical images. During this night no topside plumes were observed, and we only compare with bottomside ESF. AMISR-14 had five beams perpendicular to the <span class="hlt">magnetic</span> field covering ~200 km in the east-west direction at 250 km altitude. Comparing the radar data with zenith ASI measurements, we found that most of the echoes occur on the western wall of the depletions with fewer echoes observed the eastern wall and center, contrary to previous comparisons of topside plumes that showed most of the echoes in the center of depleted regions. We attribute these differences to the occurrence of irregularities produced at submeter scales by the lower hybrid drift instability. Comparisons of the ASI observations with JULIA images show similar results to those found in the AMISR-14 and ASI comparison.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011PhDT.......193W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011PhDT.......193W"><span id="translatedtitle">Quantum Mechanical Simulation and X-Ray Scattering Applied to Pressure-Induced Invar <span class="hlt">Anomaly</span> in <span class="hlt">Magnetic</span> Iron Alloy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Winterrose, Michael L.</p> <p></p> <p>The Invar effect has remained at the forefront of materials research since Charles-Edouard Guillaume discovered the vanishing thermal expansion of Fe-Ni alloys in 1897. More recently, a pressure-induced Invar effect was discovered in Fe-Ni alloys, and the relationship between classical and pressure-induced Invar phenomena has added complexity to the century-old struggle to comprehend the microscopic origins of Invar behavior. In this thesis I present our recent discovery of pressure-induced Invar behavior in Pd3Fe with the ordered L12 structure. Nuclear forward scattering measurements show that the ferromagnetic ground state in Pd3Fe is destabilized with pressure, collapsing around 10GPa (V/V 0=0.96) to a low-spin <span class="hlt">magnetic</span> state. From high-pressure synchrotron x-ray diffraction measurements we find a large volume collapse at ambient temperature to accompany the collapse of ferromagnetism. After the volume collapse there is a significant increase in the bulk modulus. Using nuclear resonant inelastic x-ray scattering to study the 57Fe phonon partial density of states (PDOS) at high pressures, we find the pressure-induced <span class="hlt">magnetic</span> transition to cause an anomalous relative softening of the average phonon frequency. Heating our sample to 650K in a furnace at a pressure of 7GPa, synchrotron x-ray diffraction measurements reveal negligible thermal expansion from 300 to 523 K, demonstrating pressure-induced Invar behavior in Pd3Fe. Density functional theory calculations identify a ferromagnetic ground state in Pd3Fe with large moments at the Fe sites. These calculations show that the application of pressure counteracts the band-filling effect of Pd. By tuning the position of the top of the 3d band with respect to the Fermi level, pressure-induced Invar behavior resembles classical Invar behavior that is controlled by chemical composition. This insight marks the first step towards a unification of our understanding of classical and pressure-induced Invar behavior. Pressure drives the majority-spin t2g antibonding electronic states closer to the Fermi level. The transition to the low-spin state occurs as these t2g states move across the Fermi level, transferring charge to the minority-spin eg nonbonding electronic states. This charge transfer reduces the internal electronic pressure in the material, giving a volume reduction in the low-spin state. The movement of the t 2g states with increasing pressure results in a greater number of states at the Fermi level, increasing screening efficiency and softening the first nearest-neighbor Fe-Pd longitudinal force constants in the low-spin state. The measured and calculated <span class="hlt">magnetic</span> transition pressures differ significantly, despite sharing similar elastic properties in both the ferromagnetic and low-spin states. The magnitude of the disagreement between theoretical and experimental <span class="hlt">magnetic</span> transition pressures suggests a spin-disordered state exists at high pressures in Pd3Fe. A shape discrepancy between the calculated and measured high-pressure Fe PDOS suggests significant short-range spin correlations exist in this spin-disordered state.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFMGP41A0975W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFMGP41A0975W"><span id="translatedtitle">Curie-point depths estimated from fractal spectral analyses of <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> in the western United States and northeast Pacific Oecan</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, J.; Li, C.</p> <p>2011-12-01</p> <p>We estimate Curie-point depths (Zb) of the western United States and northeast Pacific Ocean by analyzing radially averaged amplitude spectra of <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> based on a fractal <span class="hlt">magnetization</span> model. The amplitude spectrum of source <span class="hlt">magnetization</span> is proportional to the wavenumber (k) raised to a fractal exponent (-β). We first test whether long-wavelength components are captured appropriately by using variable overlapping windows ranging in sizes from 75 × 75 km2 to 200 × 200 km2. For each sliding window, the amplitude spectrum is pre-multiplied with the factor k-β prior to computation. We then use the centroid method (Tanaka et al., 1999) to calculate Zb. We find that when the window size approaches 200 × 200 km2 the resolution of estimated Zb is too low to reveal important geological features. For our study, fractal exponents larger than 0.6 will result in overcorrection. Considering the difficulty of simultaneous inversion of the depths to the top and centroid of <span class="hlt">magnetic</span> sources (Zt and Z0 respectively) and β, we fix β = 0.5 for the whole study area. Note that β here is defined for amplitude spectrum, which is equivalent to 1 for power spectrum of 2D <span class="hlt">magnetic</span> sources. Our results show that the estimated Curie depths range from 4 km to 40 km. The average Zb in the northern part of the northeast Pacific Ocean is about 14 km below the sea level, and almost the same depths are found in the junction of the active and ancient Cascade arcs and remanent track of Yellowstone hotspot. Subduction beneath the North American plate and consequent magmatism can account for small Zb in the above mentioned volcanic arc regions. The Mendocino Triple Junction separates the northeast Pacific into northern (mainly consisting of the Explorer, Juan de Fuca and Gorda plates) and southern parts. Both the Zb and the thickness of <span class="hlt">magnetic</span> layer in the southern part are larger than those in the northern part. This contrast is due to the fact that the Pacific plate to the south is older and colder, and has larger water depths, than the northern plates. It is noticed that a narrow E-W zone showing anomalous Zb and Zt around 44°N in Oregon might be associated with the rise of Yellowstone plume and tearing of Juan de Fuca Plate. The largest Curie depths up to about 40 km are mainly found in the southern parts of Colorado Plateaus and Middle Rocky Mountains, and these depths are well correlated to low surface heat flow. Based on the correlation curves between Curie depths and surface heat flow, we deduct that varying the fractal exponent β from 0.5 down to 0 (in the case of random distribution of 2D <span class="hlt">magnetic</span> sources) will increase the deducted effective average thermal conductivity of the <span class="hlt">magnetic</span> layer from 2~3 W (m°C)-1 to 3~4 W (m°C)-1. These thermal conductivities are comparable to those measured from basalts and granites, also putting reasonable constraints on fractal exponent β and Curie depths.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19870059984&hterms=trm&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dtrm','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19870059984&hterms=trm&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dtrm"><span id="translatedtitle"><span class="hlt">Magnetization</span> of the oceanic crust - Thermoremanent <span class="hlt">magnetization</span> of chemical remanent <span class="hlt">magnetization</span>?</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Raymond, C. A.; Labrecque, J. L.</p> <p>1987-01-01</p> <p>A model was proposed in which chemical remanent <span class="hlt">magnetization</span> (CRM) acquired within the first 20 Ma of crustal evolution may account for 80 percent of the bulk natural remanent <span class="hlt">magnetization</span> (NRM) of older basalts. The CRM of the crust is acquired as the original thermoremanent <span class="hlt">magnetization</span> (TRM) is lost through low temperature alteration. The CRM intensity and direction are controlled by the post-emplacement polarity history. This model explains several independent observations concerning the <span class="hlt">magnetization</span> of the oceanic crust. The model accounts for amplitude and skewness dicrepancies observed in both the intermediate wavelength satellite field and the short wavelength sea surface <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> pattern. It also explains the decay of <span class="hlt">magnetization</span> away from the <span class="hlt">spreading</span> axis, and the enhanced <span class="hlt">magnetization</span> of the Cretaceous Quiet Zones while predicting other systematic variations with age in the bulk <span class="hlt">magnetization</span> of the oceanic crust. The model also explains discrepancies in the <span class="hlt">anomaly</span> skewness parameter observed for <span class="hlt">anomalies</span> of Cretaceous age. Further studies indicate varying rates of TRM decay in very young crust which depicts the advance of low temperature alteration through the <span class="hlt">magnetized</span> layer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFMGP34A..04B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFMGP34A..04B"><span id="translatedtitle">Unique Aeromagnetic-radar Ice-sounding Survey over the West Antarctic Ice Sheet Allows Three Dimensional Definition of Sources of <span class="hlt">Magnetic</span> <span class="hlt">Anomalies</span> Caused by Subglacial Volcanic Sources at the Bed of the Ice</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Behrendt, J. C.; Casertz; Soar Teams</p> <p>2011-12-01</p> <p>The West Antarctic Ice Sheet (WAIS) flows through the volcanically active West Antarctic Rift System (WARS). The aeromagnetic method has proven the most useful geophysical tool for studying subglacial volcanic rocks beneath the WAIS since early surveys in the 1950s. The Central West Antarctica (CWA) aerogeophysical survey covering ~354,000 km2 (about the area of Nevada and California combined) over the WAIS, consisting of a 5-km line-spaced, orthogonal set of aeromagnetic, radar ice-sounding and aerogravity measurements, is a unique Antarctic data set. This 1990-97 survey (CASERTZ and SOAR), still provides invaluable information on subglacial volcanic rocks, particularly when combined with widely spaced older aeromagnetic flight lines over a much greater area. These combined survey data indicate numerous high-amplitude (100->1000 nT), 5-50 km width, shallow-source, <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> over a very extensive area (>1.2 x 106 km2) mostly resulting from subglacial volcanic eruptions. I interpreted the <span class="hlt">anomalies</span> sampled in the CWA survey as defining ~1000 "volcanic centers" requiring high remanent normal <span class="hlt">magnetizations</span> in the present field direction. About 400 of these <span class="hlt">anomaly</span> sources (conservatively selected) are correlated with bed topography. The tops of >80% of these <span class="hlt">anomaly</span> sources have <200 m relief at the bed of the WAIS. They appear modified by moving ice, requiring a younger age than the WAIS (~25 Ma). The 5 km by 5 km orthogonal flight line survey obviated aliasing of the <span class="hlt">magnetic</span> and radar ice sounding data, because it is approximately equivalent to the flight elevation above the ice (1 km) surface plus the ice thickness (2-3 km); it reveals the <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> and the tops of volcanic sources at its bed in three dimensions. Models (2 1/2 D) fit to a number of the <span class="hlt">magnetic</span> <span class="hlt">anomalies</span>, whose sources are at the bed of the ice sheet are constrained by topography measured by the radar ice sounding. Volcanoes in the WARS are <34 Ma, but at least four are active today. Most "volcanic centers" are buried beneath the WAIS; if a few are active today, subglacial volcanism may well have a significant effect on the WAIS regime. Aerogeophysical data (Blankenship et al., 1993, Mt. Casertz; Corr and Vaughan, 2008, near Hudson Mts.) indicated active subglacial volcanism, and suggested volcanic effects on WAIS dynamics. Future effects on the stability of the WAIS should not be ignored, as the present rapid changes resulting from global warming, could be accelerated by subglacial volcanism.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19900031386&hterms=Aphrodite&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DAphrodite','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19900031386&hterms=Aphrodite&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DAphrodite"><span id="translatedtitle">Terrestrial <span class="hlt">spreading</span> centers under Venus conditions - Evaluation of a crustal <span class="hlt">spreading</span> model for Western Aphrodite Terra</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Sotin, C.; Senske, D. A.; Head, J. W.; Parmentier, E. M.</p> <p>1989-01-01</p> <p>The model of Reid and Jackson (1981) for terrestrial <span class="hlt">spreading</span> centers is applied to Venus conditions. On the basis of <span class="hlt">spreading</span> rate, mantle temperature, and surface temperature, the model predicts both isostatic topography and crustal thickness. The model and Pioneer Venus altimetry and gravity data are used to test the hypothesis of Head and Crumpler (1987) that Western Aphrodite Terra is the location of crustal <span class="hlt">spreading</span> on Venus. It is concluded that a <span class="hlt">spreading</span> center model for Ovda Regio in Western Aphrodite Terra could account for the observed topography and line-of-sight gravity <span class="hlt">anomalies</span> found in the Pioneer data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JMiMi..25l4001W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JMiMi..25l4001W"><span id="translatedtitle">Tuning magnetofluidic <span class="hlt">spreading</span> in microchannels</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Zhaomeng; Varma, V. B.; Wang, Z. P.; Ramanujan, R. V.</p> <p>2015-12-01</p> <p>Magnetofluidic <span class="hlt">spreading</span> (MFS) is a phenomenon in which a uniform <span class="hlt">magnetic</span> field is used to induce <span class="hlt">spreading</span> of a ferrofluid core cladded by diamagnetic fluidic streams in a three-stream channel. Applications of MFS include micromixing, cell sorting and novel microfluidic lab-on-a-chip design. However, the relative importance of the parameters which govern MFS is still unclear, leading to non-optimal control of MFS. Hence, in this work, the effect of various key parameters on MFS was experimentally and numerically studied. Our multi-physics model, which combines <span class="hlt">magnetic</span> and fluidic analysis, showed excellent agreement between theory and experiment. It was found that <span class="hlt">spreading</span> was mainly due to cross-sectional convection induced by <span class="hlt">magnetic</span> forces, and can be enhanced by tuning various parameters. Smaller flow rate ratio, higher <span class="hlt">magnetic</span> field, higher core stream or lower cladding stream dynamic viscosity, and larger <span class="hlt">magnetic</span> particle size can increase MFS. These results can be used to tune magnetofluidic <span class="hlt">spreading</span> in microchannels.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17..787D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17..787D"><span id="translatedtitle">Electromagnetic Particle-in-Cell Simulations of the Solar Wind Interaction with Lunar <span class="hlt">Magnetic</span> <span class="hlt">Anomalies</span>: Interaction Mechanisms Under Varying Solar Wind Conditions.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Deca, Jan; Divin, Andrey; Lapenta, Giovanni; Lembège, Bertrand; Markidis, Stefano; Horányi, Mihály</p> <p>2015-04-01</p> <p>We present three-dimensional fully kinetic and electromagnetic simulations of the solar wind interaction with lunar crustal <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> (LMAs). Using the implicit particle-in-cell code iPic3D, we confirm that LMAs may indeed be strong enough to stand off the solar wind from directly impacting the lunar surface forming a mini-magnetosphere, as suggested by spacecraft observations and theory. In contrast to earlier MHD and hybrid simulations, the fully kinetic nature of iPic3D allows to investigate the space charge effects and in particular the electron dynamics dominating the near-surface lunar plasma environment. We describe the general picture of the interaction of a dipole model centered just below the lunar surface under various solar wind and plasma conditions, and focus afterwards on the ion and electron kinetic behavior of the system. It is shown that the configuration is dominated by electron motion, because the LMA scale size is small with respect to the gyroradius of the solar wind ions. We identify a population of backstreaming ions, the deflection of <span class="hlt">magnetized</span> electrons via the ExB-drift motion and the subsequent formation of a halo region of elevated density around the dipole source. Finally, it is shown that the presence and efficiency of the latter mechanisms are heavily impacted by the upstream plasma conditions and, on their turn, influence the overall structure and evolution of the LMA system. Our work opens new frontiers of research toward a deeper understanding of LMAs and is ideally suited to be compared with field or particle observations from spacecraft such as Kaguya (SELENE), Lunar Prospector or ARTEMIS. The ability to evaluate the implications for future lunar exploration as well as lunar science in general hinges on a better understanding of LMAs. This research has received funding from the European Commission's FP7 Program with the grant agreement SWIFF (project 2633430, swiff.eu) and EHEROES (project 284461, www.eheroes.eu). The simulations were conducted on the computational resources provided by the PRACE Tier-0 project 2011050747 (Curie) and 2013091928 (SuperMUC). This research was supported by the Swedish National Space Board, Grant No. 136/11. JD has received support through the HPC-Europa2 visitor programme (project HPC08SSG85) and the KuLeuven Junior Mobility Programme Special Research Fund.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMGP23A3665D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMGP23A3665D"><span id="translatedtitle">Equivalent <span class="hlt">magnetization</span> over the World's Ocean</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dyment, J.; Choi, Y.; Hamoudi, M.; Erwan, T.; Lesur, V.</p> <p>2014-12-01</p> <p>As a by-product of our recent work to build a candidate model over the oceans for the World Digital <span class="hlt">Magnetic</span> <span class="hlt">Anomaly</span> Map (WDMAM) version 2, we derived global distributions of the equivalent <span class="hlt">magnetization</span> in oceanic domains. In a first step, we use classic point source forward modeling on a spherical Earth to build a forward model of the marine <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> at sea-surface. We estimate <span class="hlt">magnetization</span> vectors using the age map of the ocean floor, the relative plate motions, the apparent polar wander path for Africa, and a geomagnetic reversal time scale. As <span class="hlt">magnetized</span> source geometry, we assume 1 km-thick layer bearing a 10 A/m <span class="hlt">magnetization</span> following the topography of the oceanic basement as defined by the bathymetry and sedimentary thickness. Adding a present-day geomagnetic field model allows the computation of our initial <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> model. In a second step, we adjust this model to the existing marine <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> data, in order to make it consistent with these data. To do so, we extract synthetic <span class="hlt">magnetic</span> along the ship tracks for which real data are available and we compare quantitatively the measured and computed <span class="hlt">anomalies</span> on 100, 200 or 400 km-long sliding windows (depending the <span class="hlt">spreading</span> rate). Among the possible comparison criteria, we discard the maximal range - too dependent on local values - and the correlation and coherency - the geographical adjustment between model and data being not accurate enough - to favor the standard deviation around the mean value. The ratio between the standard deviations of data and model on each sliding window represent an estimate of the <span class="hlt">magnetization</span> ratio causing the <span class="hlt">anomalies</span>, which we interpolate to adjust the initial <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> model to the data and therefore compute a final model to be included in our WDMAM candidate over the oceanic regions lacking data. The above ratio, after division by the <span class="hlt">magnetization</span> of 10 A/m used in the model, represents an estimate of the equivalent <span class="hlt">magnetization</span> under the considered <span class="hlt">magnetized</span> source geometry. The resulting distributions of equivalent <span class="hlt">magnetization</span> are discussed in terms of mid-ocean ridges, presence of hotspots and oceanic plateaus, and the age of the oceanic lithosphere. Global marine <span class="hlt">magnetic</span> data sets and models represent a useful tool to assess first order <span class="hlt">magnetic</span> properties of the oceanic lithosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..1511639C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..1511639C"><span id="translatedtitle">Seafloor <span class="hlt">spreading</span> initiation in the Red Sea: constraints from geophysical data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cocchi, Luca; Ligi, Marco; Bonatti, Enrico; Caratori Tontini, Fabio; Rasul, Najeeb</p> <p>2013-04-01</p> <p>Multibeam, <span class="hlt">magnetics</span>, gravity and seismic reflection data from the two northernmost oceanic axial segments of the Red Sea, Thetis and Nereus, reveal that the initial accretion of oceanic crust in the central Red Sea occurs in discrete axial deeps. Thetis Deep is made by coalescence of three sub-basins that become shallower and narrower from south to north. The initial emplacement of oceanic crust, that occurred at South Thetis and Central Nereus roughly ~2.2 and ~2 Ma, respectively, is taking place today in the northern Thetis and southern Nereus tips. The "intertrough zones" that separate the Thetis axial "oceanic" cell from the Nereus cell to the north, and the Hadarba cell to the south, are devoid of <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> and contain thick sediment sequences and relicts of continental crust. The Red Sea central depressed region broadens significantly in the inter-trough zones relative to the "oceanic" segments, indicating that deformation becomes focused in a narrow axial zone as soon as oceanic accretion starts. <span class="hlt">Magnetic</span> <span class="hlt">anomalies</span> suggests a south to north time progression of the initial emplacement of oceanic crust within the Thetis system, with a propagation rate of roughly 30 mm/a, significantly faster than the <span class="hlt">spreading</span> rate (6.1 mm/a). <span class="hlt">Magnetic</span> profiles from the northern part of Hadarba Deep (the "oceanic" segment immediately to the south of Thetis), indicate an initial oceanic accretion at ~3 Ma, confirming the south to north progression. Quantitative modelling of <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> suggests that, at Thetis and Nereus, the oceanic <span class="hlt">spreading</span> initiated by a strong pulse of "active" oceanic crust generation and rapid sea floor <span class="hlt">spreading</span>. This initial burst of crust accretion is observed at the sub-basin scale of Thetis and Nereus deeps. Our results suggest that each initial discrete axial cell taps a different asthenospheric source and serves as nucleus for axial propagation of oceanic accretion, resulting in linear segments of <span class="hlt">spreading</span>. Discrete oceanic initial crust accretion is observed also in the southern portion of the Red Sea. In fact, reprocessing of all sea-surface <span class="hlt">magnetic</span> data from the Red Sea allowed to reconstruct the evolution of the entire divergent margin, showing a northward migration of the initial emplacement of the oceanic crust with an average propagation rate of ~22 mm/a. Although the impingement from below of the Afar mantle plume may have influenced the evolution of the Red Sea rift, independent along-axis centres of upwelling developed during the rifting stage, due to buoyancy-driven convection within the hot, low viscosity asthenosphere beneath the extending continental lithosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003EAEJA....11043O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003EAEJA....11043O"><span id="translatedtitle">The World's Fastest Ultraslow <span class="hlt">Spreading</span> Ridge: Marianas Extinct Backarc</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ohara, Y.; Snow, J. E.; Okino, K.; Ishii, T.</p> <p>2003-04-01</p> <p>In the Marianas backarc there has been extensive seafloor <span class="hlt">spreading</span> during the past 27 Ma. Detailed <span class="hlt">magnetic</span> surveys document intermediate <span class="hlt">spreading</span> rates (7-8 cm/yr) throughout this time. A plate reorganization from E-W to nearly N-S rifting that commenced about 20 Ma. During that time, magmatic supply to the ridge died out and the ridge jumped to the east to the present site of rifting, the Mariana Trough, about 6 million years ago. During the cruise KR03-01, we have documented the petrologic and morphologic characteristics of this basin, and shown it to be characterized by a dramatic magmatic undersupply more typical of an ultraslow <span class="hlt">spreading</span> ridge than of a fast <span class="hlt">spreading</span> ridge in a backarc basin. Two zones of the Parece Vela Basin were examined in detail during the cruise KR03-01 in early 2003. The first of these is a region of chaotic terrain ranging in age from about 25 to 20 Ma. In this area, the otherwise orderly N-S trending abyssal hill topography of the rest of the basin fails, leaving a terrain composed largely of E-W striking megamullion structures and deep regions (over 6000m), associated with a large mantle Bouguer <span class="hlt">anomaly</span>. The extent of mullion-dominated topography in this basin is much greater than previously recognized. Less than 20% of the crust in this region consists of N-S striking magmatically accreted structures. Dredging on one of the many megamullion structures returned fertile mantle peridotites, and gabbros documenting an extremely thin crust with extensive tectonic dismemberment. The crust to the east of this region is younger, and documents the <span class="hlt">spreading</span> shift from E-W to NNE-SSW. A giant megamullion structure ('Godzilla Mullion') is developed here over a 55 km wide ridge segment. Multiple dredge hauls on this structure reveal it to be composed nearly entirely of fertile mantle peridotite along its entire length of over 120 km. This suggests a peridotite exposure of some ~7000 km2, one of the largest exposures of amagmatic ocean crust in the world. At the same time, the rift axis is extremely deep, some 6500 m ( ~5000 m after correction for 10Ma subsidence), and there is a pronounced rift valley, with the development of deep large-offset fracture zones typical of slow and ultraslow <span class="hlt">spreading</span> ridges. We attribute the magmatic undersupply to the dying out of <span class="hlt">spreading</span> along the rift zone, which took a few million years to complete. The results imply that the morphologic and petrologic characteristics of ridges we normally assume to be a direct function of <span class="hlt">spreading</span> rate are in fact solely a function of magmatic supply.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/20713765','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/20713765"><span id="translatedtitle">Observational manifestations of <span class="hlt">anomaly</span> inflow</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Boyarsky, Alexey; Shaposhnikov, Mikhail</p> <p>2005-10-15</p> <p>In theories with chiral couplings, one of the important consistency requirements is that of the cancellation of a gauge <span class="hlt">anomaly</span>. In particular, this is one of the conditions imposed on the hypercharges in the standard model. However, <span class="hlt">anomaly</span> cancellation condition of the standard model looks unnatural from the perspective of a theory with extra dimensions. Indeed, if our world were embedded into an odd-dimensional space, then the full theory would be automatically <span class="hlt">anomaly</span>-free. In this paper we discuss the physical consequences of <span class="hlt">anomaly</span> noncancellation for effective 4-dimensional field theory. We demonstrate that in such a theory parallel electric and <span class="hlt">magnetic</span> fields get modified. In particular, this happens for any particle possessing both electric charge and <span class="hlt">magnetic</span> moment. This effect, if observed, can serve as a low energy signature of extra dimensions. On the other hand, if such an effect is absent or is very small, then from the point of view of any theory with extra dimensions it is just another fine-tuning and should acquire theoretical explanation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014GeoJI.197.1273R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014GeoJI.197.1273R"><span id="translatedtitle"><span class="hlt">Spreading</span> behaviour of the Pacific-Farallon ridge system since 83 Ma</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rowan, Christopher J.; Rowley, David B.</p> <p>2014-06-01</p> <p>We present improved rotations, complete with uncertainties, for the Pacific-Farallon Ridge (PFR) between geomagnetic chrons 34y (83 Ma) and 10y (28.28 Ma). Despite substantial shortening since ˜55 Ma, this ridge system and its remnants (e.g. the East Pacific Rise) have produced as much as 45 per cent of all oceanic lithosphere created since the Late Cretaceous, but reconstructions face the twin challenges of extensive subduction of Farallon crust-which precludes reconstruction by fitting conjugate <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> and fracture zone (FZ) traces-and asymmetric <span class="hlt">spreading</span> behaviour for at least the past 51 Myr. We have calculated best-fit `half'-angle stage rotations between nine geomagnetic chron boundaries (34y, 33y, 29o, 24.3o, 20o, 18.2o, 17.1y, 13y and 10y) using combined <span class="hlt">anomaly</span> and FZ data from both the northern and southern Pacific Plate. For rotations younger than chron 24.3o, estimates for <span class="hlt">spreading</span> asymmetry, derived using <span class="hlt">anomaly</span> picks from yet-to-be subducted Farallon/Nazca crust in the south Pacific, allow full stage rotations to be calculated. Between 50 and 83 Ma, where no direct constraints on <span class="hlt">spreading</span> asymmetry are possible, a `best-fit' full stage rotation was calculated based on the net Nazca:Pacific <span class="hlt">spreading</span> asymmetry (Pacific <span class="hlt">spreading</span> fraction fPAC = 0.44) over the past 50 Myr, with conservative lower and upper bounds, based on variability in the degree of <span class="hlt">spreading</span> asymmetry over periods of <15 Myr, assuming fPACs of 0.5 and 0.36, respectively. Synthetic flowlines generated from our new stage rotation produce a better match to Pacific FZ trends than previously published rotations. With the exception of the chron 18o-20o rotation, the six stage poles for rotations between chrons 33y and 13y (74-33 Ma) all cluster tightly at 60-75°E, 60-68°N, consistent with the relatively constant trend of the major Pacific FZs. This stability spans at least one episode of Farallon Plate fragmentation caused by subduction of PFR segments beneath the Americas, at 55-48 Ma, which appears to have greatly accelerated divergence on the surviving ridge without significantly affecting the location of the instantaneous rotation pole. Together with quasi-periodic 15-20 Myr variations in the degree of <span class="hlt">spreading</span> asymmetry that also appear to correlate with changes in <span class="hlt">spreading</span> rate, this indicates that forces other than slab pull may be a factor in determining Pacific-Farallon Plate motions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMGP51C1087C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMGP51C1087C"><span id="translatedtitle">Estimation of hydrothermal deposits location from <span class="hlt">magnetization</span> distribution and <span class="hlt">magnetic</span> properties in the North Fiji Basin</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Choi, S.; Kim, C.; Park, C.; Kim, H.</p> <p>2013-12-01</p> <p>The North Fiji Basin is belong to one of the youngest basins of back-arc basins in the southwest Pacific (from 12 Ma ago). We performed the marine <span class="hlt">magnetic</span> and the bathymetry survey in the North Fiji Basin for finding the submarine hydrothermal deposits in April 2012. We acquired <span class="hlt">magnetic</span> and bathymetry datasets by using Multi-Beam Echo Sounder EM120 (Kongsberg Co.) and Overhouser Proton Magnetometer SeaSPY (Marine <span class="hlt">Magnetics</span> Co.). We conducted the data processing to obtain detailed seabed topography, <span class="hlt">magnetic</span> <span class="hlt">anomaly</span>, reduce to the pole(RTP), analytic signal and <span class="hlt">magnetization</span>. The study areas composed of the two areas(KF-1(longitude : 173.5 ~ 173.7 and latitude : -16.2 ~ -16.5) and KF-3(longitude : 173.4 ~ 173.6 and latitude : -18.7 ~ -19.1)) in Central <span class="hlt">Spreading</span> Ridge(CSR) and one area(KF-2(longitude : 173.7 ~ 174 and latitude : -16.8 ~ -17.2)) in Triple Junction(TJ). The seabed topography of KF-1 existed thin horst in two grabens that trends NW-SE direction. The <span class="hlt">magnetic</span> properties of KF-1 showed high <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> in center part and <span class="hlt">magnetic</span> lineament structure of trending E-W direction. In the <span class="hlt">magnetization</span> distribution of KF-1, the low <span class="hlt">magnetization</span> zone matches well with a strong analytic signal in the northeastern part. KF-2 area has TJ. The seabed topography formed like Y-shape and showed a high feature in the center of TJ. The <span class="hlt">magnetic</span> properties of KF-2 displayed high <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> in N-S <span class="hlt">spreading</span> ridge center and northwestern part. In the <span class="hlt">magnetization</span> distribution of KF-2, the low <span class="hlt">magnetization</span> zone matches well with a strong analytic signal in the northeastern part. The seabed topography of KF-3 presented a flat and high topography like dome structure at center axis and some seamounts scattered around the axis. The <span class="hlt">magnetic</span> properties of KF-3 showed high <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> in N-S <span class="hlt">spreading</span> ridge center part. In the <span class="hlt">magnetization</span> of KF-2, the low <span class="hlt">magnetization</span> zone mismatches to strong analytic signal in this area. The difference of KF-3 between the low <span class="hlt">magnetization</span> zones and the analytic signals is considered that the submarine <span class="hlt">magnetic</span> strength of KF-3 is lower than that of KF-1 and KF-2. The <span class="hlt">spreading</span> ridges of the study areas showed common Central <span class="hlt">Anomaly</span> <span class="hlt">Magnetization</span> Highs (CAMH). As a whole, the previous studies on the structure of this study area (Auzende et al, 1990) support our results of the <span class="hlt">magnetic</span> properties (<span class="hlt">Magnetic</span> <span class="hlt">Anomaly</span> and RTP). We can expect to have the better results by comparing with the other study like geophysics (seismic), geology, and geochemistry in this area. Reference Auzende, J.M., and 29 others, Active <span class="hlt">Spreading</span> and Hydrothermalism in North Fiji Basin(SW Pacific). Results of Japanese French Cruise Kaiyo 87, Marine Geophysical Researches., 12, 269-283, 1990.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMSM33A..04D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMSM33A..04D"><span id="translatedtitle">Electromagnetic Particle-in-Cell Simulations of the Solar Wind Interaction with Lunar <span class="hlt">Magnetic</span> <span class="hlt">Anomalies</span>: Ion and Electron Dynamics Under Varying Solar Wind Conditions.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Deca, J.; Divin, A. V.; Lapenta, G.; Lembege, B.; Markidis, S.; Horanyi, M.</p> <p>2014-12-01</p> <p>We present three-dimensional fully kinetic and electromagnetic simulations of the solar wind interaction with lunar crustal <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> (LMAs). Using the implicit particle-in-cell code iPic3D, we confirm that LMAs may indeed be strong enough to stand off the solar wind from directly impacting the lunar surface forming a mini-magnetosphere, as suggested by spacecraft observations and theory. In contrast to earlier MHD and hybrid simulations, the fully kinetic nature of iPic3D allows to investigate the space charge effects and in particular the electron dynamics dominating the near-surface lunar plasma environment. We describe the general picture of the interaction of a dipole model centered just below the lunar surface under various solar wind and plasma conditions, and focus afterwards on the ion and electron kinetic behavior of the system. It is shown that the configuration is dominated by electron motion, because the LMA scale size is small with respect to the gyroradius of the solar wind ions. The dominant LMA interaction mechanism is also highly dependent on the solar wind and IMF conditions. Driven by strong pressure anisotropies, the mini-magnetosphere is also unstable over time, leading to only temporal shielding of the surface underneath. Our work opens new frontiers of research toward a deeper understanding of LMAs and is ideally suited to be compared with field or particle observations from spacecraft such as Kaguya (SELENE), Lunar Prospector or ARTEMIS. The ability to evaluate the implications for future lunar exploration as well as lunar science in general hinges on a better understanding of LMAs. This research has received funding from the European Commission's FP7 Program with the grant agreement SWIFF (project 2633430, swiff.eu) and EHEROES (project 284461, www.eheroes.eu). The simulations were conducted on the computational resources provided by the PRACE Tier-0 project 2011050747 (Curie) and 2013091928 (SuperMUC). This research was supported by the Swedish National Space Board, Grant No. 136/11. JD has received support through the HPC-Europa2 visitor programme (project HPC08SSG85) and the KuLeuven Junior Mobility Programme Special Research Fund.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26993977','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26993977"><span id="translatedtitle">Accuracy and Internal Consistency of Cardiac <span class="hlt">Magnetic</span> Resonance Imaging in Measuring Branch Pulmonary Artery Flows in Patients With Conotruncal <span class="hlt">Anomalies</span> and Branch Pulmonary Artery Stents.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Harris, Matthew A; Avitabile, Catherine M; Fu, Gregory L; Kim, Daniel W; Kim, Timothy S; Gillespie, Matthew J; Keller, Marc S; Fogel, Mark A; Whitehead, Kevin K</p> <p>2016-04-01</p> <p>Clinicians use branch pulmonary artery (BPA) blood flow distribution to help determine the need for intervention. Although phase-contrast <span class="hlt">magnetic</span> resonance (PCMR) flow measurements are accurate, this has never been shown in the vicinity of a BPA ferromagnetic stent (FS) which produces significant susceptibility artifact. We retrospectively reviewed 49 consecutive PCMR studies performed from 2005 to 2012 on patients with repaired conotruncal <span class="hlt">anomalies</span> and either left (n = 29) or right PA (n = 20) stents. Three methods of measuring the stented BPA flow were compared: (1) main PA (MPA) minus nonstented BPA, (2) direct PCMR of stented BPA away from the artifact, and (3) pulmonary venous flows (ipsilateral to stented BPA and derived pulmonary blood flow ratio from bilateral pulmonary venous flows). Internal consistency was tested with the Student t test, linear regression, Bland-Altman analysis, and intraclass correlation (ICC). The mean age was 11.7 ± 6.9 years with 5.8 ± 4.2 years between stent placement and CMR. There was good agreement without significant difference between MPA-derived stented BPA flow (method 1) and direct PCMR of stented BPA (method 2; 41 ± 19% vs 39 ± 19%, p = 0.59; R(2) = 0.84, p <0.001; ICC = 0.96). There was also good agreement between methods 1 and 2 compared to pulmonary venous flows, with the highest correlation occurring between method 2 and ipsilateral pulmonary venous flow (R(2) = 0.90, p <0.001; ICC = 0.97 for MPA-derived-stented BPA flow; R(2) = 0.94, p <0.001; ICC = 0.98 for direct PCMR of stented BPA). Eleven of the 49 patients (22%) underwent interventional catheterization after PCMR. In conclusion, in the vicinity of a BPA FS, accurate measurement of the net fractional pulmonary blood flow ratio is feasible. PCMR adjacent to the stent and ipsilateral pulmonary venous flows provide the most internally consistent data. These data underscore PCMR's utility in managing patients with implanted FS. PMID:26993977</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1988Tectp.155...49S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1988Tectp.155...49S"><span id="translatedtitle">Seafloor <span class="hlt">spreading</span> history of the western North Atlantic Basin derived from the Keathley sequence and computer graphics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sundvik, Michael T.; Larson, Roger L.</p> <p>1988-12-01</p> <p>An analysis of sea-surface <span class="hlt">magnetic</span> profiles and an aeromagnetic contour chart west of Bermuda yields a new tectonic framework for the Keathley (M-series) seafloor <span class="hlt">spreading</span> <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> sequence. Changes in <span class="hlt">spreading</span> direction derived from the western Keathley sequence occur at times corresponding to M24, M21 and M11, of which M11 is a time of continental breakup. The models facilitate new identifications of the <span class="hlt">anomalies</span> between M16 and M4, obviating the need for anomalously slow <span class="hlt">spreading</span> between M11 and M4, previously suggested by other workers and by us, and placing the location of the well-defined rough-smooth basement boundary at M11. The models show that <span class="hlt">spreading</span> rates contemporaneously vary among profiles collected between flowlines as determined by a recently presented kinematic history. This strongly suggests that individual ridge axis segments act independently of another in detail. Our reconstruction technique records in map form where the ridge crest has made significant departures from perfect symmetry and a predictable <span class="hlt">spreading</span> rate during its evolutionary history. Among eight profiles collected parallel to seafloor <span class="hlt">spreading</span> flowlines in the western North Atlantic encompassing only 2700 km of "normal" oceanic crust we can identify more than fourteen ridge-jump events. There is evidence for a small (≈ 30 km) ridge jump to the east of many ridge axis segments at M24. This is supported in the eastern North Atlantic conjugate crust of the Canary basin where M25 and M24 are poorly represented. A series of four ridge jumps to the east along one paleoridge axis segment now located at 36°N, 65°W is related to the passage of the Mesozoic Mid-Atlantic Ridge crest over the Verde hotspot at ≈ 137 m.y. B.P. The Project <span class="hlt">Magnet</span> <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> contour chart for the area between 29° N and 40° N has been used to determine stage poles of motion for processes occurring at the ridge crest related to its segmentation, which have a component oblique to <span class="hlt">spreading</span> between chrons M21 and M11. These trends may relate to the motion of the ridge crest over the mantle.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22056164','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22056164"><span id="translatedtitle">High Occurrence of Aberrant Lymph Node <span class="hlt">Spread</span> on <span class="hlt">Magnetic</span> Resonance Lymphography in Prostate Cancer Patients With a Biochemical Recurrence After Radical Prostatectomy</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Meijer, Hanneke J.M.; Lin, Emile N. van; Debats, Oscar A.; Witjes, J. Alfred; Span, Paul N.; Kaanders, Johannes H.A.M.; Barentsz, Jelle O.</p> <p>2012-03-15</p> <p>Purpose: To investigate the pattern of lymph node <span class="hlt">spread</span> in prostate cancer patients with a biochemical recurrence after radical prostatectomy, eligible for salvage radiotherapy; and to determine whether the clinical target volume (CTV) for elective pelvic irradiation in the primary setting can be applied in the salvage setting for patients with (a high risk of) lymph node metastases. Methods and Materials: The charts of 47 prostate cancer patients with PSA recurrence after prostatectomy who had positive lymph nodes on <span class="hlt">magnetic</span> resonance lymphography (MRL) were reviewed. Positive lymph nodes were assigned to a lymph node region according to the guidelines of the Radiation Therapy Oncology Group (RTOG) for delineation of the CTV for pelvic irradiation (RTOG-CTV). We defined four lymph node regions for positive nodes outside this RTOG-CTV: the para-aortal, proximal common iliac, pararectal, and paravesical regions. They were referred to as aberrant lymph node regions. For each patient, clinical and pathologic features were recorded, and their association with aberrant lymph drainage was investigated. The distribution of positive lymph nodes was analyzed separately for patients with a prostate-specific antigen (PSA) <1.0 ng/mL. Results: MRL detected positive aberrant lymph nodes in 37 patients (79%). In 20 patients (43%) a positive lymph node was found in the pararectal region. Higher PSA at the time of MRL was associated with the presence of positive lymph nodes in the para-aortic region (2.49 vs. 0.82 ng/mL; p = 0.007) and in the proximal common iliac region (1.95 vs. 0.59 ng/mL; p = 0.009). There were 18 patients with a PSA <1.0 ng/mL. Ten of these patients (61%) had at least one aberrant positive lymph node. Conclusion: Seventy-nine percent of the PSA-recurrent patients had at least one aberrant positive lymph node. Application of the standard RTOG-CTV for pelvic irradiation in the salvage setting therefore seems to be inappropriate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ClinicalTrials.gov/ct2/show/study/NCT02399527','CLINICALTRIALS'); return false;" href="https://ClinicalTrials.gov/ct2/show/study/NCT02399527"><span id="translatedtitle">Lymphatic <span class="hlt">Anomalies</span> Registry</span></a></p> <p><a target="_blank" href="http://www.clinicaltrials.gov/ct/screen/SimpleSearch">ClinicalTrials.gov</a></p> <p></p> <p>2015-11-04</p> <p>Lymphatic Malformation; Generalized Lymphatic <span class="hlt">Anomaly</span> (GLA); Central Conducting Lymphatic <span class="hlt">Anomaly</span>; CLOVES Syndrome; Gorham-Stout Disease ("Disappearing Bone Disease"); Blue Rubber Bleb Nevus Syndrome; Kaposiform Lymphangiomatosis; Kaposiform Hemangioendothelioma/Tufted Angioma; Klippel-Trenaunay Syndrome; Lymphangiomatosis</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/22253657','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/22253657"><span id="translatedtitle">Dynamic Diffusion <span class="hlt">Magnetic</span> Resonance Imaging of Infarct Formation and Peri-infarct <span class="hlt">Spreading</span> Depression after Middle Cerebral Artery Occlusion (MCAO) in macacca fasicularis.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>D'Arceuil, Helen E; de Crespigny, Alex</p> <p>2011-01-01</p> <p>Dynamic diffusion MRI was used to visualize hyperacute stroke formation in the brain of a cynomolgus macaque. Under fluoroscopic guidance, a microcatheter was placed into the middle cerebral artery (MCA). The animal was immediately transferred to a 1.5T clinical scanner. Dynamic T2-weighted imaging during bolus injection of Oxygen-17 enriched water through the microcatheter mapped out the territory perfused by the MCA segment. Serial diffusion measurements were made using diffusion-weighted echo-planar imaging, with a temporal resolution of 15 seconds, during injection of a glue embolus into the microcatheter. The apparent diffusion coefficient declined within the lesion core. A wave of transient diffusion decline <span class="hlt">spread</span> through peripheral uninvolved brain immediately following stroke induction. The propagation speed and pattern is consistent with <span class="hlt">spreading</span> peri-infarct depolarizations (PID). The detection of PIDs following embolic stroke in a higher nonhuman primate brain supports the hypothesis that <span class="hlt">spreading</span> depressions may occur following occlusive stroke in humans. PMID:22253657</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20010021221&hterms=Gallagher+JR&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DGallagher%2BJR','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20010021221&hterms=Gallagher+JR&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DGallagher%2BJR"><span id="translatedtitle">Magnetosheath Flow <span class="hlt">Anomalies</span> in 3-D</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Vaisberg, O. L.; Burch, J. L.; Smirnov, V. N.; Avanov, L. A.; Moore, T. E.; Waite, J. H., Jr.; Skalsky, A. A.; Borodkova, N. L.; Coffey, V. N.; Gallagher, D. L.; Rose, M. Franklin (Technical Monitor)</p> <p>2000-01-01</p> <p>Measurements of the plasma and <span class="hlt">magnetic</span> field with high temporal resolution on the Interball Tail probe reveal many flow <span class="hlt">anomalies</span> in the magnetosheath. They are usually seen as flow direction and number density variations, accompanied by <span class="hlt">magnetic</span> field discontinuities. Large flow <span class="hlt">anomalies</span> with number density variations of factor of 2 or more and velocity variations of 100 km/s or more are seen with periodicity of about I per hour. The cases of flow <span class="hlt">anomalies</span> following in succession are also observed, and suggest their decay while propagating through the magnetosheath. Some magnetospheric disturbances observed in the outer magnetosphere after the satellite has crossed the magnetopause on the inbound orbit suggest their association with magnetosheath flow <span class="hlt">anomalies</span> observed in the magnetosheath prior to magnetopause crossing.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19760015183','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19760015183"><span id="translatedtitle">Analysis of spacecraft <span class="hlt">anomalies</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bloomquist, C. E.; Graham, W. C.</p> <p>1976-01-01</p> <p>The <span class="hlt">anomalies</span> from 316 spacecraft covering the entire U.S. space program were analyzed to determine if there were any experimental or technological programs which could be implemented to remove the <span class="hlt">anomalies</span> from future space activity. Thirty specific categories of <span class="hlt">anomalies</span> were found to cover nearly 85 percent of all observed <span class="hlt">anomalies</span>. Thirteen experiments were defined to deal with 17 of these categories; nine additional experiments were identified to deal with other classes of observed and anticipated <span class="hlt">anomalies</span>. Preliminary analyses indicate that all 22 experimental programs are both technically feasible and economically viable.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JHEP...02..078A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JHEP...02..078A"><span id="translatedtitle">Lifshitz scale <span class="hlt">anomalies</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Arav, Igal; Chapman, Shira; Oz, Yaron</p> <p>2015-02-01</p> <p>We analyse scale <span class="hlt">anomalies</span> in Lifshitz field theories, formulated as the relative cohomology of the scaling operator with respect to foliation preserving diffeomorphisms. We construct a detailed framework that enables us to calculate the <span class="hlt">anomalies</span> for any number of spatial dimensions, and for any value of the dynamical exponent. We derive selection rules, and establish the <span class="hlt">anomaly</span> structure in diverse universal sectors. We present the complete cohomologies for various examples in one, two and three space dimensions for several values of the dynamical exponent. Our calculations indicate that all the Lifshitz scale <span class="hlt">anomalies</span> are trivial descents, called B-type in the terminology of conformal <span class="hlt">anomalies</span>. However, not all the trivial descents are cohomologically non-trivial. We compare the conformal <span class="hlt">anomalies</span> to Lifshitz scale <span class="hlt">anomalies</span> with a dynamical exponent equal to one.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010Tectp.494..226W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010Tectp.494..226W"><span id="translatedtitle">Rifting to <span class="hlt">spreading</span> in the southern Lau Basin: Variations within the transition zone</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Watanabe, M.; Okino, K.; Kodera, T.</p> <p>2010-11-01</p> <p>The Lau Basin and Havre Trough are back-arc basins related to Pacific-Australian plate convergence. Seafloor <span class="hlt">spreading</span> occurs in the Lau Basin whereas the Havre Trough is in a rifting stage. At present, the <span class="hlt">spreading</span> propagator's tip lies at the southern end of the Valu Fa Ridge (VFR) at 22°40'S. Studying this propagation process provides an opportunity to characterize the evolution of rifting to the initiation of seafloor <span class="hlt">spreading</span> which is fundamental to back-arc basin development. New geophysical data of the southern Lau Basin reveals that as <span class="hlt">spreading</span> propagates south, it evolves in a discrete style south of 22°40'S. The propagation axis lies along the eastern margin of the basin, where the well defined, linear VFR loses its identifying morphology. Topography in this eastern zone is characterized by grabens separated by short narrow ridges. High backscatter intensity indicates tectonic and magmatic activity in this eastern area. Mantle Bouguer <span class="hlt">anomalies</span> (MBA) increase southwards from the VFR to form an elevated MBA area extending west from the currently active area. This indicates eastward migration of active rifting, during which the arc crust was extremely thinned. High <span class="hlt">magnetization</span> is observed in a left-stepping pattern south of the VFR. We interpret this pattern as discrete segments that characterize the initiation of the <span class="hlt">spreading</span> stage. There is no evidence of a single, continuous <span class="hlt">spreading</span> axis like that which characterizes the central and northern Lau Basin. The <span class="hlt">magnetization</span> highs are discrete and are observed in areas where deformation and magmatism are focused. They are offset relative to the VFR, though they generally follow the same north-south trend as the VFR.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/1019346','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/1019346"><span id="translatedtitle">Quantum <span class="hlt">Spread</span> Spectrum Communication</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Humble, Travis S</p> <p>2011-01-01</p> <p>We show that communication of single-photon quantum states in a multi-user environment is improved by using <span class="hlt">spread</span> spectrum communication techniques. We describe a framework for <span class="hlt">spreading</span>, transmitting, despreading, and detecting single-photon spectral states that mimics conventional <span class="hlt">spread</span> spectrum techniques. We show in the cases of inadvertent detection, unintentional interference, and multi-user management, that quantum <span class="hlt">spread</span> spectrum communications may minimize receiver errors by managing quantum channel access.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1992E%26PSL.113..323S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1992E%26PSL.113..323S"><span id="translatedtitle">Kinematics of the North American-African plate boundary between 28° and 29°N during the last 10 Ma: evolution of the axial geometry and <span class="hlt">spreading</span> rate and direction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sloan, H.; Patriat, Ph.</p> <p>1992-10-01</p> <p>A high-resolution survey, SARA (Segmentation Ancienne de la Ride Atlantique) collected Sea Beam bathymetry, <span class="hlt">magnetic</span>, gravity and seismic reflection data on the flanks of the Mid-Atlantic Ridge between 28° and 29°N. This survey was designed to complement a portion of an on-axis study carried out between the Atlantis and Kane transform faults, which revealed the configuration of the <span class="hlt">spreading</span> axis. The SARA survey extends this coverage to an age of approximately 10 Ma on either flank. A sinuous isochron pattern was established from <span class="hlt">anomaly</span> identification made using a two-dimensional model. The plate tectonic reconstruction, based solely on this isochron pattern, provides an accurate kinematic description of the relative motion between the African and North American plates within the zone. Our results, confirmed by data from the FAMOUS area and a flowline comparison with the trend of the Kane fracture zone, show that a change in axial orientation, <span class="hlt">spreading</span> direction and <span class="hlt">spreading</span> rate occurred at approximately <span class="hlt">anomaly</span> 4 time (7.01 Ma). This was coincident with the appearance of a new axial segment. All the axial segments observed have changed length continously during the last 10 Ma by advancing or retreating at one or both ends in any combination so as to leave non-parallel trails on the flanks that do not align with either the <span class="hlt">spreading</span> direction or with the absolute plate motion. Factors contributing to the sinuous <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> pattern are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMGP21B..06K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMGP21B..06K"><span id="translatedtitle">Crustal <span class="hlt">Magnetization</span> and <span class="hlt">Magnetic</span> Petrology in Basalts - What Can We Learn from Scientific Drillings?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kontny, A. M.</p> <p>2014-12-01</p> <p>Rock <span class="hlt">magnetic</span> and magneto-mineralogical data from scientific drillings contribute to our understanding of the growth history and tectonic evolution of volcanic structures and allows for an improved interpretation of <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> data. Such data are not only important for the <span class="hlt">magnetic</span> structure of volcanic buildings and <span class="hlt">spreading</span> ridges on Earth but may also provide basic data for the interpretation of extraterrestrial <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> like on Mars. Crustal <span class="hlt">magnetization</span> of basalts is well studied since decades and in general, the amplitude of <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> is mainly related to the induced and remanent <span class="hlt">magnetization</span>. Direct measurements of the <span class="hlt">magnetic</span> field and measurements of <span class="hlt">magnetic</span> properties of oceanic and continental crust have indicated that the crustal <span class="hlt">magnetization</span> is very complex and depends on different factors like e.g. magma composition, cooling rate, age and hydrothermal alteration. Generally a high oxygen fugacity (above the NNO buffer) and a low Ti/(Ti+Fe) ratio of the basaltic melt are suggested as a precondition for high concentration of <span class="hlt">magnetic</span> minerals and therefore high primary TRM. High temperature subsolidus reactions and hydrothermal alteration as e.g. observed in the strongly <span class="hlt">magnetic</span> basalts from the Stardalur drill core, Iceland, seems to increase NRM intensity and <span class="hlt">magnetic</span> susceptibility due to creation of small, secondary magnetite (Vahle et al. 2007). Probably the increase occurred after the extinction of the hydrothermal system because active high-temperature (>150 °C) geothermal areas like the Krafla caldera, NE-Iceland, often show distinct <span class="hlt">magnetic</span> lows in aeromagnetic <span class="hlt">anomaly</span> maps suggesting a destruction of <span class="hlt">magnetic</span> minerals by hydrothermal activity (Oliva-Urcia et al. 2011). The destruction explains the significant <span class="hlt">magnetization</span> loss, which is seen in many local <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> lows within the oceanic crust and volcanic islands like Iceland or Hawaii. Borehole and core <span class="hlt">magnetic</span> susceptibility measurements in combination with rock <span class="hlt">magnetic</span> and <span class="hlt">magnetic</span> mineralogy studies will be shown from scientific drillings from Hawaii and Iceland, which illustrate how vertical core sections can be used to deduce these processes. References Oliva-Urcia et al. (2011) Geophys J. Intern. 186, 1, 155-174. Vahle et al. (2007) Phys. Earth Planet. Inter. 164, 119-141.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2801930','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2801930"><span id="translatedtitle">Taussig-Bing <span class="hlt">Anomaly</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Konstantinov, Igor E.</p> <p>2009-01-01</p> <p>Taussig-Bing <span class="hlt">anomaly</span> is a rare congenital heart malformation that was first described in 1949 by Helen B. Taussig (1898–1986) and Richard J. Bing (1909–). Although substantial improvement has since been achieved in surgical results of the repair of the <span class="hlt">anomaly</span>, management of the Taussig-Bing <span class="hlt">anomaly</span> remains challenging. A history of the original description of the <span class="hlt">anomaly</span>, the life stories of the individuals who first described it, and the current outcomes of its surgical management are reviewed herein. PMID:20069085</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000JHEP...03..030B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000JHEP...03..030B"><span id="translatedtitle"><span class="hlt">Anomalies</span> and tadpoles</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bianchi, Massimo; Morales, Jose F.</p> <p>2000-03-01</p> <p>We show that massless RR tadpoles in vacuum configurations with open and unoriented strings are always related to <span class="hlt">anomalies</span>. RR tadpoles arising from sectors of the internal SCFT with non-vanishing Witten index are in one-to-one correspondence with conventional irreducible <span class="hlt">anomalies</span>. The anomalous content of the remaining RR tadpoles can be disclosed by considering anomalous amplitudes with higher numbers of external legs. We then provide an explicit parametrization of the <span class="hlt">anomaly</span> polynomial in terms of the boundary reflection coefficients, i.e. one-point functions of massless RR fields on the disk. After factorization of the reducible <span class="hlt">anomaly</span>, we extract the relevant WZ couplings in the effective lagrangians.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140002250','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140002250"><span id="translatedtitle">Hot Flow <span class="hlt">Anomalies</span> at Venus</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Collinson, G. A.; Sibeck, David Gary; Boardsen, Scott A.; Moore, Tom; Barabash, S.; Masters, A.; Shane, N.; Slavin, J.A.; Coates, A.J.; Zhang, T. L.; Sarantos, M.</p> <p>2012-01-01</p> <p>We present a multi-instrument study of a hot flow <span class="hlt">anomaly</span> (HFA) observed by the Venus Express spacecraft in the Venusian foreshock, on 22 March 2008, incorporating both Venus Express Magnetometer and Analyzer of Space Plasmas and Energetic Atoms (ASPERA) plasma observations. Centered on an interplanetary <span class="hlt">magnetic</span> field discontinuity with inward convective motional electric fields on both sides, with a decreased core field strength, ion observations consistent with a flow deflection, and bounded by compressive heated edges, the properties of this event are consistent with those of HFAs observed at other planets within the solar system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012SPIE.8404E..0BE','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012SPIE.8404E..0BE"><span id="translatedtitle">Partial <span class="hlt">spread</span> OFDM</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Elghariani, Ali; Zoltowski, Michael D.</p> <p>2012-05-01</p> <p>In this paper, partial <span class="hlt">spread</span> OFDM system has been presented and its performance has been studied when different detection techniques are employed, such as minimum mean square error (MMSE), grouped Maximum Likelihood (ML) and approximated integer quadratic programming (IQP) techniques . The performance study also includes applying two different <span class="hlt">spreading</span> matrices, Hadamard and Vandermonde. Extensive computer simulation have been implemented and important results show that partial <span class="hlt">spread</span> OFDM system improves the BER performance and the frequency diversity of OFDM compared to both non <span class="hlt">spread</span> and full <span class="hlt">spread</span> systems. The results from this paper also show that partial <span class="hlt">spreading</span> technique combined with suboptimal detector could be a better solution for applications that require low receiver complexity and high information detectability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/23710135','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/23710135"><span id="translatedtitle">Splenic <span class="hlt">anomalies</span> of shape, size, and location: pictorial essay.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yildiz, Adalet Elcin; Ariyurek, Macit Orhan; Karcaaltincaba, Musturay</p> <p>2013-01-01</p> <p>Spleen can have a wide range of <span class="hlt">anomalies</span> including its shape, location, number, and size. Although most of these <span class="hlt">anomalies</span> are congenital, there are also acquired types. Congenital <span class="hlt">anomalies</span> affecting the shape of spleen are lobulations, notches, and clefts; the fusion and location <span class="hlt">anomalies</span> of spleen are accessory spleen, splenopancreatic fusion, and wandering spleen; polysplenia can be associated with a syndrome. Splenosis and small spleen are acquired <span class="hlt">anomalies</span> which are caused by trauma and sickle cell disease, respectively. These <span class="hlt">anomalies</span> can be detected easily by using different imaging modalities including ultrasonography, computed tomography, <span class="hlt">magnetic</span> resonance imaging, and also Tc-99m scintigraphy. In this pictorial essay, we review the imaging findings of these <span class="hlt">anomalies</span> which can cause diagnostic pitfalls and be interpreted as pathologic processes. PMID:23710135</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19870007996','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19870007996"><span id="translatedtitle"><span class="hlt">Magnetization</span> of the oceanic crust: TRM or CRM?</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Raymond, C. A.; Labrecque, J. L.</p> <p>1987-01-01</p> <p>A model was proposed in which chemical remanent <span class="hlt">magnetization</span> (CRM) acquired within the first 20 Ma of crustal evolution may account for 80% of the bulk natural remanent <span class="hlt">magnetization</span> (NRM) of older basalts. The CRM of the crust is acquired as the original thermoremanent <span class="hlt">magnetization</span> (TRM) is lost through low temperature alteration. The CRM intensity and direction are controlled by the post-emplacement polarity history. This model explains several independent observations concerning the <span class="hlt">magnetization</span> of the oceanic crust. The model accounts for amplitude and skewness discrepancies observed in both the intermediate wavelength satellite field and the short wavelength sea surface <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> pattern. It also explains the decay of <span class="hlt">magnetization</span> away from the <span class="hlt">spreading</span> axis, and the enhanced <span class="hlt">magnetization</span> of the Cretaceous Quiet Zones while predicting other systematic variations with age in the bulk <span class="hlt">magnetization</span> of the oceanic crust. The model also explains discrepancies in the <span class="hlt">anomaly</span> skewness parameter observed for <span class="hlt">anomalies</span> of Cretaceous age. Further studies indicate varying rates of TRM decay in very young crust which depicts the advance of low temperature alteration through the <span class="hlt">magnetized</span> layer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6636118','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6636118"><span id="translatedtitle">Aeromagnetic <span class="hlt">anomalies</span> and perspective oil traps in China</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Zhang, Y.X. )</p> <p>1994-10-01</p> <p>Based on analyses of aeromagnetic data from known oil and gas fields in China, aeromagnetic <span class="hlt">anomalies</span> have been classified according to their genesis into three types: (1) structure-associated <span class="hlt">anomalies</span> related to volcanic rocks, (2) <span class="hlt">anomalies</span> related to <span class="hlt">magnetic</span> basement fault blocks, and (3) structure-associated <span class="hlt">anomalies</span> related to weakly <span class="hlt">magnetic</span> sedimentary strata. The most successful applications of aeromagnetic data for locating favorable oil and gas structures are in the following kinds of areas: (1) areas where basement fault blocks of inhomogeneous lithology and <span class="hlt">magnetization</span> are developed; (2) areas of weakly <span class="hlt">magnetic</span> layered strata with a considerably thickness, either effusive or clastic deposits; and (3) areas where <span class="hlt">magnetic</span> layers have undergone tectonic deformation with faulting and dip angles larger than 30 degrees. For reliable detection of such structures in sedimentary rocks and associated oil and gas traps, an integrated interpretation of geological and geophysical data is necessary.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.T32B..01H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.T32B..01H"><span id="translatedtitle">Seafloor <span class="hlt">Spreading</span> Reorganization South of Iceland</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hey, R. N.; Martinez, F.; Benediktsdottir, A.; Hoskuldsson, A.</p> <p>2011-12-01</p> <p>There is a major ongoing diachronous reorganization of North Atlantic seafloor <span class="hlt">spreading</span> occurring at present south of Iceland, from an orthogonal ridge/transform geometry to the present oblique <span class="hlt">spreading</span> geometry without transform faults on the Reykjanes Ridge. This reorganization is presently interpreted as a thermal phenomenon, with a pulse of warmer mantle expanding away from the Iceland plume causing a progressive change in subaxial mantle rheology from brittle to ductile, so that transform faults can no longer be maintained. Given that this is certainly the most obvious and arguably the type-example of active plate boundary reorganization, it is somewhat surprising that a thermal mechanism has near universal acceptance here whereas most if not all other seafloor <span class="hlt">spreading</span> reorganizations are equally universally thought to result from the tectonic rift propagation mechanism. This suggests the possibility that either the thermal model might be wrong here, or that the propagating rift (PR) model might be wrong elsewhere. The reason the PR alternative was ignored here was that the younger seafloor record flanking the Reykjanes Ridge consisting of V-shaped ridges, troughs & scarps (VSRs) enclosed by the reorganization wake seemed to prove that there had been no rift propagation. It had long been thought that these VSRs were symmetric about the <span class="hlt">spreading</span> axis, & if this conventional wisdom (that led directly to the pulsing Iceland plume model) were true, rift propagation, which must produce asymmetry, could not have occurred. However, our expedition collected marine geophysical data that showed that the VSRs actually have an asymmetric geometry consistent with rift propagation, not with previous pulsing plume models, & thus they can no longer be considered convincing proof of a pulsing Iceland plume. Although we had previously noted that plume pulses might drive the propagators away from Iceland, a significant new result (Benediktsdóttir et al., 2011) is that excellent <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> fits can only be achieved if some rift propagation toward Iceland has also occurred. These newly identified propagators toward Iceland can't be driven by plume pulses even if the ones propagating away from Iceland are. Rift propagation is an alternative way to produce V-shaped wakes of thin crust & grabens, e.g. Earth's deepest axial valley is at the tip of the Pito propagator which has created the transient Easter microplate. (Hey had the great pleasure of sailing on the Nautile expedition Jean Francheteau led to Pito Deep, & after that advised his students to sail on French ships every chance they got). The involvement of rift propagation in VSR formation suggests this is also a possible explanation for the ongoing major transform-fault eliminating reorganization. If so, the tip of the reorganization would presently be near the first transform fault south of Iceland, the Bight transform near 56.8N, rather than in the extensively surveyed area 200 km farther north where the thermal reorganization model predicted the reorganization tip should be.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013SolED...5.2449B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013SolED...5.2449B"><span id="translatedtitle"><span class="hlt">Magnetic</span> signature of large exhumed mantle domains of the Southwest Indian Ridge: results from a deep-tow geophysical survey over 0 to 11 Ma old seafloor</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bronner, A.; Sauter, D.; Munschy, M.; Carlut, J.; Searle, R.; Cannat, M.; Manatschal, G.</p> <p>2013-12-01</p> <p>We investigate the <span class="hlt">magnetic</span> signature of an ultramafic seafloor in the eastern part of the Southwest Indian Ridge (SWIR). There, detachment faulting, continuous over 11 Myrs, exhumed large areas of mantle derived rocks. These exhumed mantle domains occur in the form of a smooth rounded topography with broad ridges locally covered by a thin highly discontinuous volcanic carapace. We present high-resolution data combining deep-tow <span class="hlt">magnetics</span>, side-scan sonar images and dredged samples collected within two exhumed mantle domains between 62° E and 65° E. We show that, despite an ultraslow <span class="hlt">spreading</span> rate, volcanic areas within robust magmatic segments are characterized by well defined seafloor <span class="hlt">spreading</span> <span class="hlt">anomalies</span>. By contrast, the exhumed mantle domains, including a few thin volcanic patches, reveal a weak and highly variable <span class="hlt">magnetic</span> pattern. The analysis of the <span class="hlt">magnetic</span> properties of the dredged samples and careful comparison between the nature of the seafloor, the deep-tow <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> and the seafloor equivalent <span class="hlt">magnetization</span> suggest that the serpentinized peridotites do not carry a sufficiently stable remanent <span class="hlt">magnetization</span> to produce seafloor <span class="hlt">spreading</span> <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> in exhumed mantle domains.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014SolE....5..339B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014SolE....5..339B"><span id="translatedtitle"><span class="hlt">Magnetic</span> signature of large exhumed mantle domains of the Southwest Indian Ridge - results from a deep-tow geophysical survey over 0 to 11 Ma old seafloor</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bronner, A.; Sauter, D.; Munschy, M.; Carlut, J.; Searle, R.; Cannat, M.; Manatschal, G.</p> <p>2014-05-01</p> <p>We investigate the <span class="hlt">magnetic</span> signature of ultramafic seafloor in the eastern part of the Southwest Indian Ridge (SWIR). There, detachment faulting, continuous over 11 Myr, exhumed large areas of mantle-derived rocks. These exhumed mantle domains occur in the form of a smooth rounded topography with broad ridges locally covered by a thin highly discontinuous volcanic carapace. We present high-resolution data combining deep-tow <span class="hlt">magnetics</span>, side-scan sonar images and dredged samples collected within two exhumed mantle domains between 62° E and 65° E. We show that, despite an ultra-slow <span class="hlt">spreading</span> rate, volcanic areas within robust magmatic segments are characterized by well-defined seafloor <span class="hlt">spreading</span> <span class="hlt">anomalies</span>. By contrast, the exhumed mantle domains, including a few thin volcanic patches, reveal a weak and highly variable <span class="hlt">magnetic</span> pattern. The analysis of the <span class="hlt">magnetic</span> properties of the dredged samples and careful comparison between the nature of the seafloor, the deep-tow <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> and the seafloor equivalent <span class="hlt">magnetization</span> suggest that the serpentinized peridotites do not carry a sufficiently stable remanent <span class="hlt">magnetization</span> to produce seafloor <span class="hlt">spreading</span> <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> in exhumed mantle domains.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19860011523','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19860011523"><span id="translatedtitle">Characterization of potential sources of <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> within the crust in a tectonically active region: Amphibolites and migmatites from Potrillo Maar, New Mexico</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Spear, F. S.; Padovanni, E.</p> <p>1985-01-01</p> <p>The purpose was to characterize the oxide mineralogy and petrology of samples collected from Potrillo Maar, New Mexico with the goal of explaining the <span class="hlt">magnetic</span> anamoly that is observed over this region from remote sensing. Potrillo Maar is a diatreme that has brought rocks from all depths in the crust to the surface almost instantaneously. The samples are therefore thought to be representative of the crust as it exists today below this portion of the Rio Grande Rift. It is generally believed that oxide minerals (magnetite, hematite, etc.) are responsible for the <span class="hlt">magnetic</span> signature of the crust. The samples from Portillo Maar therefore offer a unique opportunity to examine the <span class="hlt">magnetic</span> mineralogy of the entire crust. The results indicate that the <span class="hlt">magnetic</span> anamoly observed over Rio Grande Rift may be consequence of the tectonic activity that caused mylonitization of the rocks and allowed the infiltration of oxidizing fluids.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMOS41C1831B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMOS41C1831B"><span id="translatedtitle">How Leaky Are Seafloor <span class="hlt">Spreading</span> Center Axes?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Baker, E. T.; Resing, J. A.; Martinez, F.; Haymon, R. M.; Nakamura, K.; Walker, S. L.; Ferrini, V.</p> <p>2013-12-01</p> <p>Some 500 active vent sites, both focused and diffuse, have now been located along <span class="hlt">spreading</span> centers by either visual confirmation or instrumental detection of the discharging plume. Discovery of the large majority of these sites was made easier by high-volume discharge of particle-laden plumes. These observations led to estimates (as can be derived from the InterRidge Vents Database) of site frequency from ~0.5-5/100 km, generally increasing with <span class="hlt">spreading</span> rate. Over the last decade, however, the increasing use of oxidation-reduction potential (ORP (mV)) (aka Eh) sensors capable of detecting minute concentrations of reduced hydrothermal chemicals (e.g., Fe+2, sulfides, Mn+2, H2, and others) suggests that these frequency estimates may be far too conservative. This hypothesis is consistent with earlier results from a few large-scale, high-resolution camera tows on some EPR segments. ORP data provide two important advantages for site identification not available with other commonly used continuously recording sensors: (1) detection of low-temperature, particle-scarce plumes, and (2) detection of reduced chemical species with very short residence times, thus increasing the location specificity of the discharge source. Here, we present high-resolution distributions of ORP <span class="hlt">anomalies</span> observed in past plume surveys along the Eastern Lau <span class="hlt">Spreading</span> Center (19.5°-22.5°S) in 2004 and 2008, the Galápagos <span class="hlt">Spreading</span> Center (94.6°-86°W) in 2005/6 and 2011, as well as new data (2011) from the East Pacific Rise (9°-10°N). Except for the 2011 GSC data (a standard CTD tow-yo), all data were collected during continuous horizontal tows of ORP sensors at various depths <~120 m above the seafloor. We used two approaches to verify that ORP <span class="hlt">anomalies</span> were authentic hydrothermal signals and not (especially in the case of small <span class="hlt">anomalies</span>) produced by some other transient chemical <span class="hlt">anomaly</span>. First, on the 2008 ELSC and 2011 EPR tows we compared temperature (ΔT) and ORP (ΔORP) data from the two deepest sensors on each tow. Although temperature <span class="hlt">anomalies</span> (ΔT°C) rarely exceeded 0.1°C, all sensors showed a positive correlation between ΔORP and ΔT (ELSC, 1569 & 1493 mV/°C, r2~0.4; EPR, 1760 & 986 mV/°C, r2~0.6). Second, comparison of tows conducted days and years apart regularly detected <span class="hlt">anomalies</span> at the same locations. While an exact enumeration of all sites is impossible from water column data alone, we estimate ~20 sites along 115 km of the EPR (17.5/100 km), ~40 sites along 425 km of the ELSC (9.4/100 km), and ~50 sites along 900 km of the GSC (5.5/100km). <span class="hlt">Anomalies</span> <~1 km apart are considered as from the same source. For the EPR and ELSC surveys, these frequencies are considerably higher than expected for ridges of similar <span class="hlt">spreading</span> rate. The higher frequencies reported here more closely match results from visual vent-mapping along 128 km of the EPR at 9°-10°N and 17°-18°S.The lower site frequency along the GSC is consistent with plume data on other ridges influenced by hotspot thermal <span class="hlt">anomalies</span>. The aggregate mass flux of discharges from numerous small sites is unknown, and could be significant; in any case, these sites may be vital oases for hydrothermal biota.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19770015851','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19770015851"><span id="translatedtitle">The <span class="hlt">anomaly</span> data base of screwworm information</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Giddings, L. E.</p> <p>1976-01-01</p> <p>Standard statistical processing of <span class="hlt">anomaly</span> data in the screwworm eradication data system is possible from data compiled on <span class="hlt">magnetic</span> tapes with the Univac 1108 computer. The format and organization of the data in the data base, which is also available on dedicated disc storage, are described.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/137614','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/137614"><span id="translatedtitle"><span class="hlt">Magnetic</span> investigations</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Bath, G.D.; Jahren, C.E.; Rosenbaum, J.G.; Baldwin, M.J.</p> <p>1983-12-31</p> <p>Air and ground <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> in the Climax stock area of the NTS help define the gross configuration of the stock and detailed configuration of <span class="hlt">magnetized</span> rocks at the Boundary and Tippinip faults that border the stock. <span class="hlt">Magnetizations</span> of geologic units were evaluated by measurements of <span class="hlt">magnetic</span> properties of drill core, minimum estimates of <span class="hlt">magnetizations</span> from ground <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> for near surface rocks, and comparisons of measured <span class="hlt">anomalies</span> with <span class="hlt">anomalies</span> computed by a three-dimensional forward program. Alluvial deposits and most sedimentary rocks are nonmagnetic, but drill core measurements reveal large and irregular changes in <span class="hlt">magnetization</span> for some quartzites and marbles. The <span class="hlt">magnetizations</span> of quartz monzonite and granodiorite near the stock surface are weak, about 0.15 A/m, and increase at a rate of 0.00196 A/m/m to 1.55 A/m, at depths greater than 700 m (2300 ft). The volcanic rocks of the area are weakly <span class="hlt">magnetized</span>. Aeromagnetic <span class="hlt">anomalies</span> 850 m (2800 ft) above the stock are explained by a model consisting of five vertical prisms. Prisms 1, 2, and 3 represent the near surface outline of the stock, prism 4 is one of the models developed by Whitehill (1973), and prism 5 is modified from the model developed by Allingham and Zietz (1962). Most of the <span class="hlt">anomaly</span> comes from unsampled and strongly-<span class="hlt">magnetized</span> deep sources that could be either granite or metamorphosed sedimentary rocks. 48 refs., 23 figs., 3 tabs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19960008391','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19960008391"><span id="translatedtitle">Flame <span class="hlt">spread</span> across liquids</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ross, Howard D.; Miller, Fletcher; Schiller, David; Sirignano, William</p> <p>1995-01-01</p> <p>Recent reviews of our understanding of flame <span class="hlt">spread</span> across liquids show that there are many unresolved issues regarding the phenomenology and causal mechanisms affecting ignition susceptibility, flame <span class="hlt">spread</span> characteristics, and flame <span class="hlt">spread</span> rates. One area of discrepancy is the effect of buoyancy in both the uniform and pulsating <span class="hlt">spread</span> regimes. The approach we have taken to resolving the importance of buoyancy for these flames is: (1) normal gravity (1g) and microgravity (micro g) experiments; and (2) numerical modeling at different gravitational levels. Of special interest to this work, as discussed at the previous workshop, is the determination of whether, and under what conditions, pulsating <span class="hlt">spread</span> occurs in micro g. Microgravity offers a unique ability to modify and control the gas-phase flow pattern by utilizing a forced air flow over the pool surface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..DFDR33002W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..DFDR33002W"><span id="translatedtitle"><span class="hlt">Spreading</span> of viscoelastic droplets</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Yuli; Minh, Do-Quang; Amberg, Gustav</p> <p>2015-11-01</p> <p>We intend to gain new insights into the <span class="hlt">spreading</span> dynamics of viscolastic droplets from a numerical perspective. Focusing on the the Giesekus droplet and the Oldroyd-B droplet, we simulated the viscous <span class="hlt">spreading</span> and the <span class="hlt">spreading</span> after impacting on a horizontal surface. The results qualitatively agree with some experimental observations on Boger fluids and shear-thinning fluids. We discuss how shear-thinning and elasticity influence the contact line motion, given detailed information on the flow field, the stress distribution and the contact line morphology in the near vicinity of the contact line. The results suggest that viscoleastic droplets can <span class="hlt">spread</span> faster than their Newtonian counterparts. The <span class="hlt">spreading</span> speed of the Oldroyd-B fluid shows dependence on elasticity while the one of the Giesekus droplet does not.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1350146','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1350146"><span id="translatedtitle">Behavioral economics without <span class="hlt">anomalies</span>.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Rachlin, H</p> <p>1995-01-01</p> <p>Behavioral economics is often conceived as the study of <span class="hlt">anomalies</span> superimposed on a rational system. As research has progressed, <span class="hlt">anomalies</span> have multiplied until little is left of rationality. Another conception of behavioral economics is based on the axiom that value is always maximized. It incorporates so-called <span class="hlt">anomalies</span> either as conflicts between temporal patterns of behavior and the individual acts comprising those patterns or as outcomes of nonexponential time discounting. This second conception of behavioral economics is both empirically based and internally consistent. PMID:8551195</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012PhRvB..86q4104M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012PhRvB..86q4104M"><span id="translatedtitle">Infrared phonon <span class="hlt">anomaly</span> and <span class="hlt">magnetic</span> excitations in single-crystal Cu3Bi(SeO3)2O2Cl</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Miller, K. H.; Stephens, P. W.; Martin, C.; Constable, E.; Lewis, R. A.; Berger, H.; Carr, G. L.; Tanner, D. B.</p> <p>2012-11-01</p> <p>Infrared reflection and transmission as a function of temperature have been measured on single crystals of Cu3Bi(SeO3)2O2Cl. The complex dielectric function and optical properties along all three principal axes of the orthorhombic cell were obtained via Kramers-Kronig analysis and by fits to a Drude-Lorentz model. Below 115 K, 16 additional modes [8(E∥â)+6(E∥b̂)+2(E∥ĉ)] appear in the phonon spectra; however, powder x-ray diffraction measurements do not detect a new structure at 85 K. Potential explanations for the new phonon modes are discussed. Transmission in the far infrared as a function of temperature has revealed <span class="hlt">magnetic</span> excitations originating below the <span class="hlt">magnetic</span> ordering temperature (Tc˜24 K). The origin of the excitations in the <span class="hlt">magnetically</span> ordered state will be discussed in terms of their response to different polarizations of incident light, behavior in externally applied <span class="hlt">magnetic</span> fields, and the anisotropic <span class="hlt">magnetic</span> properties of Cu3Bi(SeO3)2O2Cl as determined by dc susceptibility measurements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhSS...58..515K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhSS...58..515K"><span id="translatedtitle">Low-temperature <span class="hlt">anomaly</span> of the <span class="hlt">magnetization</span> in alloys (Pr,Dy, M)2(Fe,Co)14B ( M = Gd, Sm, Nd)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kablov, E. N.; Ospennikova, O. G.; Rezchikova, I. I.; Valeev, R. A.; Cherednichenko, I. V.; Kunitsyna, E. I.; Morgunov, R. B.; Piskorskii, V. P.</p> <p>2016-03-01</p> <p>It has been found that temperature dependences of the saturation <span class="hlt">magnetization</span> of sintered hard <span class="hlt">magnetic</span> (Pr,Dy, M)2(Fe,Co)14B ( M = Gd, Sm, Nd) alloys demonstrate an increase at a temperature lower than a critical temperature (150 K for Sm and Nd and 70 K for Gd). An additive of copper does not influence the critical temperature. It has been assumed that there is a low-temperature phase in which cobalt is replaced with boron that diffuses from the (Pr,Dy,Gd)(Fe,Co)4B phase to the near-surface region of grains of the main <span class="hlt">magnetic</span> (Pr,Dy,Gd)2(Fe,Co)14B phase.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhRvD..93h4021F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhRvD..93h4021F"><span id="translatedtitle"><span class="hlt">Anomalies</span>, entropy, and boundaries</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fursaev, Dmitry V.; Solodukhin, Sergey N.</p> <p>2016-04-01</p> <p>A relation between the conformal <span class="hlt">anomaly</span> and the logarithmic term in the entanglement entropy is known to exist for CFTs in even dimensions. In odd dimensions, the local <span class="hlt">anomaly</span> and the logarithmic term in the entropy are absent. As was observed recently, there exists a nontrivial integrated <span class="hlt">anomaly</span> if an odd-dimensional spacetime has boundaries. We show that, similarly, there exists a logarithmic term in the entanglement entropy when the entangling surface crosses the boundary of spacetime. The relation of the entanglement entropy to the integrated conformal <span class="hlt">anomaly</span> is elaborated for three-dimensional theories. Distributional properties of intrinsic and extrinsic geometries of the boundary in the presence of conical singularities in the bulk are established. This allows one to find contributions to the entropy that depend on the relative angle between the boundary and the entangling surface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015SuScT..28a5001M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015SuScT..28a5001M"><span id="translatedtitle"><span class="hlt">Anomalies</span> in vortex lattice dynamics driven by induced ac currents in superconducting films with <span class="hlt">magnetic</span> arrays of two-fold symmetry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Moreno, A. J.; Chiliotte, C. E.; Pasquini, G.; Bekeris, V.; Gomez, A.; del Valle, J.; Gonzalez, E. M.; Prieto, J. L.; Vicent, J. L.</p> <p>2015-01-01</p> <p>We study the dynamics of the vortex lattice driven by ac induced currents in the critical state regime, for T > 0.70 TC. The samples are superconducting films grown on top of two-fold symmetry array of <span class="hlt">magnetic</span> dots. In these heterostructures, the induced ac currents flow parallel to the short and to the long side of the pinning array in different areas of the samples simultaneously. This behavior produces remarkable effects in the vortex lattice dynamics. First of all, periodic features are observed in the ac susceptibility versus applied <span class="hlt">magnetic</span> field measurements which are related to matching effects between the vortex lattices and the <span class="hlt">magnetic</span> array. However, the vortex lattice reconfiguration observed in magnetotransport experiments is absent. Some of these features are revealed as maxima instead of being minima, indicating higher mobility at certain matching fields. Competing unstable vortex configurations could lead to increase vortex mobility precluding the reconfiguration transition. At high temperatures, where the matching effects show up, the <span class="hlt">magnetic</span> permeability of the dots is the mechanism that governs the JC(T) behavior. Moreover, the temperature dependence of the pinning force FP(T) shows a temperature crossover related to an unexpected enhancement in vortex mobility. Vortex-vortex interaction and the interplay between trapped and interstitial vortices are a hint to explain these phenomena.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25241096','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25241096"><span id="translatedtitle">Complex lymphatic <span class="hlt">anomalies</span>.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Trenor, Cameron C; Chaudry, Gulraiz</p> <p>2014-08-01</p> <p>Complex lymphatic <span class="hlt">anomalies</span> include several diagnoses with overlapping patterns of clinical symptoms, anatomic location, imaging features, hematologic alterations, and complications. Lymphatic malformations likely arise through anomalous embryogenesis of the lymphatic system. Analysis of clinical, imaging, histologic, and hematologic features is often needed to reach a diagnosis. Aspiration of fluid collections can readily define fluid as chylous or not. The presence of chyle indicates dysfunction at the mesenteric or retroperitoneal level or above the cisterna chyli due to reflux. The imaging patterns of generalized lymphatic <span class="hlt">anomaly</span> (GLA) and Gorham-Stout disease have been segregated with distinctive bone lesions and peri-osseous features. More aggressive histology (spindled lymphatic endothelial cells), clinical progression, hemorrhage, or moderate hematologic changes should raise suspicion for kaposiform lymphangiomatosis. Biopsy may be needed for diagnosis, though avoidance of rib biopsy is advised to prevent iatrogenic chronic pleural effusion. Lymphangiography can visualize the anatomy and function of the lymphatic system and may identify dysfunction of the thoracic duct in central conducting lymphatic <span class="hlt">anomalies</span>. Local control and symptom relief are targeted by resection, laser therapy, and sclerotherapy. Emerging data suggest a role for medical therapies for complications of complex lymphatic <span class="hlt">anomalies</span>. Outcomes include recurrent effusion, infection, pain, fracture, mortality, and rarely, malignancy. Complex lymphatic <span class="hlt">anomalies</span> present significant diagnostic and therapeutic challenges. Results from a phase 2 study of sirolimus in these and other conditions are expected in 2014. Improved characterization of natural history, predictors of poor outcomes, responses to therapy, and further clinical trials are needed for complex lymphatic <span class="hlt">anomalies</span>. PMID:25241096</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/22032505','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/22032505"><span id="translatedtitle">Neuroimaging in craniovertebral <span class="hlt">anomalies</span> as seen in the tropics.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sankhe, Shilpa S; Kumar, S K Susheel</p> <p>2011-11-01</p> <p>Craniovertebral junction (CVJ) disorders in the Occident are usually associated with systemic disorders. In contrast, in the Orient, a greater incidence of isolated CVJ <span class="hlt">anomalies</span> is seen. Although these are developmental <span class="hlt">anomalies</span>, they manifest late in life, with trauma and/or infection playing a promotive role. The most significant and common of these <span class="hlt">anomalies</span> are basilar invagination and atlantodental dislocation, which also occur together. Accurate diagnosis of these <span class="hlt">anomalies</span> is feasible using computed tomography and <span class="hlt">magnetic</span> resonance imaging. Greater awareness of this subset of patients is essential for greater understanding and effective management of these ailments. PMID:22032505</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2247774','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2247774"><span id="translatedtitle">Modeling cortical <span class="hlt">spreading</span> depression.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Reggia, J. A.; Montgomery, D.</p> <p>1994-01-01</p> <p>Cortical <span class="hlt">spreading</span> depression is a wave of electrical silence and biochemical changes that <span class="hlt">spreads</span> across the cerebral cortex. Recently there has been a growing recognition that it may be an important pathophysiological event in a number of neurological disorders. In this paper, we describe a reaction-diffusion model of the extracellular potassium changes that are a central part of this process. Simulations with the model show that an appropriate stimulus evokes a moving wave of increased potassium with many similarities to that seen experimentally. The resultant model is a useful computational tool for future study of the effects of <span class="hlt">spreading</span> depression on the cortex. PMID:7950049</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6037136','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6037136"><span id="translatedtitle">Latitudinal extent of the equatorial <span class="hlt">anomaly</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Klobuchar, J.A.; Anderson, D.N.; Doherty, P.H.</p> <p>1990-05-03</p> <p>The latitudinal extent of the equatorial <span class="hlt">anomaly</span> has been studied using a theoretical model of the ionosphere which incorporates measured values of vertical E x B drift at the earth's <span class="hlt">magnetic</span> equator. Realistic values of neutral winds are also included. The equatorial <span class="hlt">anomaly</span> region, typically between plus and minus 20 degrees <span class="hlt">magnetic</span> latitude, is that part of the world where the highest values of electron density and Total Electron Content, (TEC), normally occur, and hence is very important to high frequency propagation and to trans-ionospheric propagation effects. During the daytime, upward E x B drift at the <span class="hlt">magnetic</span> equator drives the ionization across field lines to higher latitudes, causing crests in ionization to occur at approximately plus and minus 15 deg dip latitude. The latitude range over which the <span class="hlt">anomaly</span> makes a significant difference in values of foF2 and TEC is calculated as a percent departure from the case with no equatorial electric field. Results from the model studies with different values of realistic electric fields show that the effects of the <span class="hlt">anomaly</span> can be highly variable and widespread in latitude and local time.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/982119','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/982119"><span id="translatedtitle">Quantum <span class="hlt">Spread</span> Spectrum Communication</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Humble, Travis S</p> <p>2010-01-01</p> <p>We demonstrate that spectral teleportation can coherently dilate the spectral probability amplitude of a single photon. In preserving the encoded quantum information, this variant of teleportation subsequently enables a form of quantum <span class="hlt">spread</span> spectrum communication.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014P%26SS...93...35U','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014P%26SS...93...35U"><span id="translatedtitle">Entry of solar-wind ions into the wake of a small body with a <span class="hlt">magnetic</span> <span class="hlt">anomaly</span>: A global Vlasov simulation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Umeda, Takayuki; Ito, Yosuke</p> <p>2014-04-01</p> <p>The interaction between a plasma flow and a small dielectric body with a weak intrinsic global <span class="hlt">magnetic</span> field is studied by means of a five-dimensional full electromagnetic Vlasov simulation with two configuration spaces and three velocity spaces. In the present study, entry processes of ions into the nightside wake tail are examined. The simulation result shows that the bow shock and the magnetopause are formed on the dayside. However, most of solar-wind ions are reflected at the dayside magnetopause and are picked up by the interplanetary <span class="hlt">magnetic</span> field. Then, a small part of the reflected ions are taken into the deep wake tail near the body by the E×B cycloid motion.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/20719041','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/20719041"><span id="translatedtitle"><span class="hlt">Magnetic</span> order and lattice <span class="hlt">anomalies</span> in the J{sub 1}-J{sub 2} model system VOMoO{sub 4}</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Bombardi, A.; Chapon, L.C.; Margiolaki, I.; Mazzoli, C.; Gonthier, S.; Duc, F.; Radaelli, P.G.</p> <p>2005-06-01</p> <p>High-resolution x-ray and neutron powder-diffraction measurements were performed on polycrystalline VOMoO{sub 4}. Below {approx_equal}40 K the system orders in a simple Neel antiferromagnetic state (propagation vector k-vector=0), indicating a dominant role of the nearest-neighbor interactions. The order is three dimensional but the reduced saturated <span class="hlt">magnetic</span> moment m of 0.41 (1) {mu}{sub B}/V{sup 4+} at 2 K indicates strongly two-dimensional character and enhanced quantum fluctuations. On cooling, there is no evidence of a reduction of the crystal symmetry. However, neutron diffraction indicates an anomalous evolution of the lattice parameters, which can be related to the onset of <span class="hlt">magnetic</span> correlations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1997JGR...102.9801R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1997JGR...102.9801R"><span id="translatedtitle">Low-energy <formula>(<1.6MeV) particle counting rates and solar <span class="hlt">magnetic</span> activity: A study of the 1980 <span class="hlt">anomaly</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rodríguez-Pacheco, J.; Sequeiros, J.; del Peral, L.; Medina, J.; Wenzel, K.-P.</p> <p>1997-05-01</p> <p>We present a study of the relation between the solar <span class="hlt">magnetic</span> activity (centered in sunspots, flares types N and B, and long-duration X class flares) and the counting rates of particles in interplanetary space with energies below 1.6 MeV obtained from the Low-Energy Proton Experiment (DFH-EPAS) onboard International Sun-Earth Explorer spacecraft, during the period 1978-1982. Our study shows that the particle counting rates are neither correlated with sunspots number nor with flares type N, but they are correlated with flares type B and mainly with long-duration X class flares. The origin of the low counting rates of particles detected during the years 1979-1980 is investigated as well. The disappearance of the strongest interplanetary shocks during that period can explain this phenomenon, at least within the energy range studied. The absence of any anomalous behavior in the flares type B and in the long-duration X class flares during this period suggests that this shock behavior can be produced by anomalous conditions of the interplanetary <span class="hlt">magnetic</span> field during the Sun's polar <span class="hlt">magnetic</span> field reversal.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22308538','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22308538"><span id="translatedtitle">Octahedral distortion induced <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> in LaMn{sub 0.5}Co{sub 0.5}O{sub 3} single crystals</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Manna, Kaustuv Elizabeth, Suja; Anil Kumar, P. S.; Bhadram, Venkata Srinu; Narayana, Chandrabhas</p> <p>2014-07-28</p> <p>Single crystals of LaMn{sub 0.5}Co{sub 0.5}O{sub 3} belonging to the ferromagnetic-insulator and distorted perovskite class were grown using a four-mirror optical float zone furnace. The as-grown crystal crystallizes into an orthorhombic Pbnm structure. The spatially resolved 2D Raman scan reveals a strain-induced distribution of transition metal (TM)–oxygen (O) octahedral deformation in the as-grown crystal. A rigorous annealing process releases the strain, thereby generating homogeneous octahedral distortion. The octahedra tilt by reducing the bond angle TM-O-TM, resulting in a decline of the exchange energy in the annealed crystal. The critical behavior is investigated from the bulk <span class="hlt">magnetization</span>. It is found that the ground state <span class="hlt">magnetic</span> behavior assigned to the strain-free LaMn{sub 0.5}Co{sub 0.5}O{sub 3} crystal is of the 3D Heisenberg kind. Strain induces mean field-like interaction in some sites, and consequently, the critical exponents deviate from the 3D Heisenberg class in the as-grown crystal. The temperature-dependent Raman scattering study reveals strong spin-phonon coupling and the existence of two <span class="hlt">magnetic</span> ground states in the same crystal.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMGP13A0759H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMGP13A0759H"><span id="translatedtitle">A M-sequence geomagnetic polarity time scale that steadies <span class="hlt">spreading</span> rates globally and incorporates cyclostratigraphy constraints</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hildebrandt, J.; Malinverno, A.; Tominaga, M.</p> <p>2010-12-01</p> <p>Geomagnetic polarity time scales (GPTSs) are constructed from <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> lineations of the Earths mid-ocean ridge system by interpolating between a few absolute radiometric dates while assuming nearly constant <span class="hlt">spreading</span> rates over time. An optimal GPTS should therefore minimize the global variation of <span class="hlt">spreading</span> rates. In current practice, however, the variation of <span class="hlt">spreading</span> rates is minimized only for a few <span class="hlt">spreading</span> centers; at all other locations worldwide, the <span class="hlt">spreading</span> rates vary rather erratically. Moreover, GPTSs constructed on the basis of oceanic <span class="hlt">magnetic</span> lineations do not directly incorporate chron durations from cyclostratigraphy. Cyclostratigraphic studies estimate the duration of a chron by matching sediment cycles with established orbital periodicities in sequences that have a measured <span class="hlt">magnetic</span> stratigraphy. Including information on these chron durations would improve the accuracy of the GPTS. We employ a Monte Carlo method to construct a GPTS that overcomes these limitations. This procedure is designed to generate a large sample of GPTSs that simultaneously match absolute age constraints, minimize the global variation of <span class="hlt">spreading</span> rates, and agree with chron durations from cyclostratigraphy. The sampled GPTSs fit these constraints within their respective uncertainties (e.g., uncertainties on chron durations from cyclostratigraphy). The objective is not only to obtain a best time scale but also to determine its uncertainty given all the information available. The mean of all the sampled GPTSs gives the final time scale, and the sample variance measures the uncertainty of the time scale. We apply the method to construct an improved version of the GPTS for the M-sequence lineations (Late Jurassic-Early Cretaceous, ~160-120 Ma). The resulting GPTS minimizes the variation in <span class="hlt">spreading</span> rates in a global data set of <span class="hlt">magnetic</span> lineations from the Western Pacific, North Atlantic, and Indian Ocean NW of Australia. The time scale also accounts for the duration of five <span class="hlt">magnetic</span> chrons (M0r through M3r) established from cyclostratigraphic studies of Lower Cretaceous sequences in the Italian Alps and Apennines. The M-sequence GPTS we obtain can be easily updated by repeating the Monte Carlo sampling with additional data that may become available in the future.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27123388','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27123388"><span id="translatedtitle">Pathology of Perineural <span class="hlt">Spread</span>.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Brown, Ian S</p> <p>2016-04-01</p> <p>The perineural space is a compartment located between the nerve axons, supporting cells and tissues, and the epineural fibrous sheath. Tumor cells invade this space in response to a complex interplay of trophic factors in the local microenviroment. This attraction of tumor cells to nerves is referred to as neurotropism. The perineural space provides a conduit for tumor <span class="hlt">spread</span> beyond the primary site of tumor occurrence. Perineural tumor growth is of two types: perineural invasion, affecting small unnamed nerves; and perineural <span class="hlt">spread</span>, affecting larger, named nerves and presenting with clinical symptoms related to the involved nerve. Both forms of perineural tumor growth represent an adverse prognostic feature and are an essential element of the histopathologic reporting of malignancies of the head and neck region. Perineural <span class="hlt">spread</span> is associated with decreased overall survival. Endoneurial invasion frequently accompanies perineural <span class="hlt">spread</span>. The epineurium is more resistant to invasion and represents an important barrier to tumor <span class="hlt">spread</span>. Immunohistochemical stains such as broad-spectrum keratin can aid in defining the proximal extent of perineural tumor <span class="hlt">spread</span>. PMID:27123388</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ISPAr.XL4...93K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ISPAr.XL4...93K"><span id="translatedtitle">Statistical <span class="hlt">Anomaly</span> Detection for Monitoring of Human Dynamics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kamiya, K.; Fuse, T.</p> <p>2015-05-01</p> <p>Understanding of human dynamics has drawn attention to various areas. Due to the wide <span class="hlt">spread</span> of positioning technologies that use GPS or public Wi-Fi, location information can be obtained with high spatial-temporal resolution as well as at low cost. By collecting set of individual location information in real time, monitoring of human dynamics is recently considered possible and is expected to lead to dynamic traffic control in the future. Although this monitoring focuses on detecting anomalous states of human dynamics, <span class="hlt">anomaly</span> detection methods are developed ad hoc and not fully systematized. This research aims to define an <span class="hlt">anomaly</span> detection problem of the human dynamics monitoring with gridded population data and develop an <span class="hlt">anomaly</span> detection method based on the definition. According to the result of a review we have comprehensively conducted, we discussed the characteristics of the <span class="hlt">anomaly</span> detection of human dynamics monitoring and categorized our problem to a semi-supervised <span class="hlt">anomaly</span> detection problem that detects contextual <span class="hlt">anomalies</span> behind time-series data. We developed an <span class="hlt">anomaly</span> detection method based on a sticky HDP-HMM, which is able to estimate the number of hidden states according to input data. Results of the experiment with synthetic data showed that our proposed method has good fundamental performance with respect to the detection rate. Through the experiment with real gridded population data, an <span class="hlt">anomaly</span> was detected when and where an actual social event had occurred.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/990773','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/990773"><span id="translatedtitle">Astrometric solar system <span class="hlt">anomalies</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Nieto, Michael Martin; Anderson, John D</p> <p>2009-01-01</p> <p>There are at least four unexplained <span class="hlt">anomalies</span> connected with astrometric data. perhaps the most disturbing is the fact that when a spacecraft on a flyby trajectory approaches the Earth within 2000 km or less, it often experiences a change in total orbital energy per unit mass. next, a secular change in the astronomical unit AU is definitely a concern. It is increasing by about 15 cm yr{sup -1}. The other two <span class="hlt">anomalies</span> are perhaps less disturbing because of known sources of nongravitational acceleration. The first is an apparent slowing of the two Pioneer spacecraft as they exit the solar system in opposite directions. Some astronomers and physicists are convinced this effect is of concern, but many others are convinced it is produced by a nearly identical thermal emission from both spacecraft, in a direction away from the Sun, thereby producing acceleration toward the Sun. The fourth <span class="hlt">anomaly</span> is a measured increase in the eccentricity of the Moon's orbit. Here again, an increase is expected from tidal friction in both the Earth and Moon. However, there is a reported unexplained increase that is significant at the three-sigma level. It is produent to suspect that all four <span class="hlt">anomalies</span> have mundane explanations, or that one or more <span class="hlt">anomalies</span> are a result of systematic error. Yet they might eventually be explained by new physics. For example, a slightly modified theory of gravitation is not ruled out, perhaps analogous to Einstein's 1916 explanation for the excess precession of Mercury's perihelion.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JGRB..119.6802E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JGRB..119.6802E"><span id="translatedtitle">Deep crustal structure of the northeastern Gulf of Mexico: Implications for rift evolution and seafloor <span class="hlt">spreading</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Eddy, Drew R.; Van Avendonk, Harm J. A.; Christeson, Gail L.; Norton, Ian O.; Karner, Garry D.; Johnson, Christopher A.; Snedden, John W.</p> <p>2014-09-01</p> <p>We image deep crustal structure using marine seismic refraction data recorded by a linear array of ocean-bottom seismometers in the Gulf of Mexico Basin Opening project (GUMBO Line 3) in order to provide new constraints on the nature of continental and oceanic crust in the northeastern Gulf of Mexico. GUMBO Line 3 extends ~524 km from the continental shelf offshore Pensacola, Florida, across the De Soto Canyon and into the central Gulf basin. Travel times from long offset, wide angle reflections and refractions resolve compressional seismic velocities and layer boundaries for sediment, crystalline crust, and upper mantle. We compare our results with coincident multichannel seismic reflection data. Our velocity model recovers shallow seismic velocities (~2.0-4.5 km/s) that we interpret as evaporites and clastic sediments. A Cretaceous carbonate platform is interpreted beneath the De Soto Canyon with seismic velocities >5.0 km/s. Crystalline continental crust thins seaward along GUMBO Line 3 from 23-10 km across the De Soto Canyon. High seismic velocity lower crust (>7.2 km/s) is interpreted as extensive syn-rift magmatism and possibly mafic underplating, common features at volcanic rift margins with high mantle potential temperatures. In the central Gulf basin we interpret thick oceanic crust (>8 km) emplaced at a slow full-<span class="hlt">spreading</span> rate (~24 mm/yr). We suggest a sustained thermal <span class="hlt">anomaly</span> during slow seafloor-<span class="hlt">spreading</span> conditions led to voluminous basalt flows from a <span class="hlt">spreading</span> ridge that overprinted seafloor <span class="hlt">magnetic</span> <span class="hlt">anomalies</span> in the northeastern Gulf of Mexico.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014GeoRL..41.1465S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014GeoRL..41.1465S"><span id="translatedtitle">Was the Midcontinent Rift part of a successful seafloor-<span class="hlt">spreading</span> episode?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stein, Carol A.; Stein, Seth; Merino, Miguel; Randy Keller, G.; Flesch, Lucy M.; Jurdy, Donna M.</p> <p>2014-03-01</p> <p>The ~1.1 Ga Midcontinent Rift (MCR), the 3000 km long largely buried feature causing the largest gravity and <span class="hlt">magnetic</span> <span class="hlt">anomaly</span> within the North American craton, is traditionally considered a failed rift formed by isolated midplate volcanism and extension. We propose instead that the MCR formed as part of the rifting of Amazonia (Precambrian northeast South America) from Laurentia (Precambrian North America) and became inactive once seafloor <span class="hlt">spreading</span> was established. A cusp in Laurentia's apparent polar wander path near the onset of MCR volcanism, recorded by the MCR's volcanic rocks, likely reflects the rifting. This scenario is suggested by analogy with younger rifts elsewhere and consistent with the MCR's extension to northwest Alabama along the East Continent Gravity High, southern Appalachian rocks having Amazonian affinities, and recent identification of contemporaneous large igneous provinces in Amazonia.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016SGeo...37....5N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016SGeo...37....5N"><span id="translatedtitle">Conductivity <span class="hlt">Anomalies</span> in Central Europe</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Neska, Anne</p> <p>2016-01-01</p> <p>This paper is a review of studies which, by applying the magnetotelluric, geomagnetic deep sounding, and magnetovariational sounding methods (the latter refers to usage of the horizontal <span class="hlt">magnetic</span> tensor), investigate Central Europe for zones of enhanced electrical conductivity. The study areas comprise the region of the Trans-European Suture Zone (i.e. the south Baltic region and Poland), the North German Basin, the German and Czech Variscides, the Pannonian Basin (Hungary), and the Polish, Slovakian, Ukrainian, and Romanian Carpathians. This part of the world is well investigated in terms of data coverage and of the density of published studies, whereas the certainty that the results lead to comprehensive interpretations varies within the reviewed literature. A comparison of spatially coincident or adjacent studies reveals the important role that the data coverage of a distinct conductivity <span class="hlt">anomaly</span> plays for the consistency of results. The encountered conductivity <span class="hlt">anomalies</span> are understood as linked to basin sediments, asthenospheric upwelling, large differences in lithospheric age, and—this concerns most of them, which all concentrate in the middle crust—tectonic boundaries that developed during all mountain building phases that have taken place on the continent.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015SGeo..tmp...38N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015SGeo..tmp...38N"><span id="translatedtitle">Conductivity <span class="hlt">Anomalies</span> in Central Europe</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Neska, Anne</p> <p>2015-11-01</p> <p>This paper is a review of studies which, by applying the magnetotelluric, geomagnetic deep sounding, and magnetovariational sounding methods (the latter refers to usage of the horizontal <span class="hlt">magnetic</span> tensor), investigate Central Europe for zones of enhanced electrical conductivity. The study areas comprise the region of the Trans-European Suture Zone (i.e. the south Baltic region and Poland), the North German Basin, the German and Czech Variscides, the Pannonian Basin (Hungary), and the Polish, Slovakian, Ukrainian, and Romanian Carpathians. This part of the world is well investigated in terms of data coverage and of the density of published studies, whereas the certainty that the results lead to comprehensive interpretations varies within the reviewed literature. A comparison of spatially coincident or adjacent studies reveals the important role that the data coverage of a distinct conductivity <span class="hlt">anomaly</span> plays for the consistency of results. The encountered conductivity <span class="hlt">anomalies</span> are understood as linked to basin sediments, asthenospheric upwelling, large differences in lithospheric age, and—this concerns most of them, which all concentrate in the middle crust—tectonic boundaries that developed during all mountain building phases that have taken place on the continent.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AIPA....5g7189F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AIPA....5g7189F"><span id="translatedtitle">Structural phase transition in La2/3Ba1/3MnO3 perovskite: Elastic, <span class="hlt">magnetic</span>, and lattice <span class="hlt">anomalies</span> and microscopic mechanism</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fertman, E.; Syrkin, E.; Lykah, V.; Desnenko, V.; Beznosov, A.; Pal-Val, P.; Pal-Val, L.; Fedorchenko, A.; Khalyavin, D.; Feher, A.</p> <p>2015-07-01</p> <p>The temperature dependences of the elastic and <span class="hlt">magnetic</span> properties of polycrystalline perovskite manganite La2/3Ba1/3MnO3 were studied using ultrasonic and SQUID magnetometer techniques. The minimum of the temperature-dependent sound velocity v(T) and corresponding maximum of the decrement δ(T) were found in the vicinity of the structural phase transition R 3 ¯ c ↔ I m m a at Ts ˜ 200 K. Large alterations of v and δ indicate a structural phase transition of the soft mode type. A high sensitivity of dc <span class="hlt">magnetization</span> to a low uniaxial pressure caused by the softening was found in the Ts region. A negative value of the linear thermal expansion coefficient along one of the crystallographic axis was found in the Imma phase near Ts. The proposed microscopic mechanism explains the appearance of the soft mode in the vicinity of the structural phase transition temperature associated with the displacement of the manganese atom from the center of the oxygen octahedron.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/19023045','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/19023045"><span id="translatedtitle">The <span class="hlt">spreading</span> of disorder.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Keizer, Kees; Lindenberg, Siegwart; Steg, Linda</p> <p>2008-12-12</p> <p>Imagine that the neighborhood you are living in is covered with graffiti, litter, and unreturned shopping carts. Would this reality cause you to litter more, trespass, or even steal? A thesis known as the broken windows theory suggests that signs of disorderly and petty criminal behavior trigger more disorderly and petty criminal behavior, thus causing the behavior to <span class="hlt">spread</span>. This may cause neighborhoods to decay and the quality of life of its inhabitants to deteriorate. For a city government, this may be a vital policy issue. But does disorder really <span class="hlt">spread</span> in neighborhoods? So far there has not been strong empirical support, and it is not clear what constitutes disorder and what may make it <span class="hlt">spread</span>. We generated hypotheses about the <span class="hlt">spread</span> of disorder and tested them in six field experiments. We found that, when people observe that others violated a certain social norm or legitimate rule, they are more likely to violate other norms or rules, which causes disorder to <span class="hlt">spread</span>. PMID:19023045</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1985JGeo....4....3C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1985JGeo....4....3C"><span id="translatedtitle">Heat flow <span class="hlt">anomalies</span> and their interpretation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chapman, David S.; Rybach, Ladislaus</p> <p>1985-12-01</p> <p>More than 10,000 heat flow determinations exist for the earth and the data set is growing steadily at about 450 observations per year. If heat flow is considered as a surface expression of geothermal processes at depth, the analysis of the data set should reveal properties of those thermal processes. They do, but on a variety of scales. For this review heat flow maps are classified by 4 different horizontal scales of 10 n km (n = 1, 2, 3 and 4) and attention is focussed on the interpretation of <span class="hlt">anomalies</span> which appear with characteristic dimensions of 10 (n - 1) km in the respective representations. The largest scale of 10 4 km encompasses heat flow on a global scale. Global heat loss is 4 10 13 W and the process of sea floor <span class="hlt">spreading</span> is the principal agent in delivering much of this heat to the surface. Correspondingly, active ocean ridge systems produce the most prominent heat flow <span class="hlt">anomalies</span> at this scale with characteristic widths of 10 3 km. Shields, with similar dimensions, exhibit negative <span class="hlt">anomalies</span>. The scale of 10 3 km includes continent wide displays. Heat flow patterns at this scale mimic tectonic units which have dimensions of a few times 10 2 km, although the thermal boundaries between these units are sometimes sharp. Heat flow <span class="hlt">anomalies</span> at this scale also result from plate tectonic processes, and are associated with arc volcanism, back arc basins, hot spot traces, and continental rifting. There are major controversies about the extent to which these surface thermal provinces reflect upper mantle thermal conditions, and also about the origin an