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Sample records for complexes petrology genesis

  1. Petrologic and In Situ Geochemical Constraints on Diogenite Genesis

    NASA Technical Reports Server (NTRS)

    Mittlefehldt, David W.; Peng, Z. X.

    2013-01-01

    Diogenites, members of the howardite, eucrite and diogenite (HED) clan, are orthopyroxenite, harzburgite and dunite meteorites [1-3]. Most are breccias, but remnant textures indicate they were originally coarse-grained rocks, with grain sizes of order of cm. Their petrography and compositions support an origin as crustal cumulates from a differentiated asteroid. Astronomical observations, and surface mineralogy and composition of Vesta determined by the Dawn spacecraft suggest that asteroid (4) Vesta is the parent object for HED meteorites [4-6]. The origin of diogenites is an unsettled issue. It is difficult to fit their bulk compositional characteristics into global magma ocean models that successfully describe the compositions of basaltic and cumulate eucrites [7]. Compositional analyses of acid-leached bulk samples have led to the hypothesis that many diogenites were formed late by interaction of their parent melts with a eucritic crust [8]. Those observations may alternatively be explained by subsolidus equilibration of trace elements between orthopyroxene and minor/ accessory phases in the rocks such as plagioclase and phosphate [7]. These competing hypotheses can be tested through in situ measurements of trace and minor elements in orthopyroxene. Our new petrologic observations and in situ minor and trace element data for a suite of diogenites are used to discuss the petrologic evolution of diogenites. Our preliminary data on two diogenites are consistent with the hypothesis that subsolidus element mobilization processes caused unusual trace element signatures seen in some diogenites [7]. We cannot stress strongly enough, however, that the sample set is too small and that additional data are required before definitive conclusions can be made.

  2. Petrological constraints upon the provenance and genesis of the East Halmahera ophiolite

    NASA Astrophysics Data System (ADS)

    Ballantyne, Paul

    This petrological and geochemical study of the ophiolitic rocks of the island of Halmahera (eastern Indonesia) has resulted in the first detailed interpretation of their tectonomagmatic provenance and suggested modern analogues around the western Pacific margin. Rocks of ophiolitic affinity are common in the eastern part of Halmahera, but structural dismemberment means that an intact ophiolite stratigraphy is not preserved. However, samples representative of each level of a "complete" ophiolite (with the possible exception of sheeted dykes) have been collected. A "mantle sequence" dominated by depleted harzburgite (spinel cr # = 62, olivine Fo 90.4, bulk (Al 2O 3 + CaO) = 1.2 wt%) suggests it is a mantle residue which has undergone a high degree of partial melt extraction. Subordinate lherzolite of relatively enriched chemistry (spinel cr # = 17, olivine Fo 90.4, bulk (Al 2O 3 + CaO) + 4.2 wt%) is interpreted as locally "fertile" upper mantle material. Cumulate rocks are well represented, particularly by olivine-free gabbronorite in which orthopyroxene and clinopyroxene occur in approximately equal modal proportions, and contain clinopyroxene with low TiO 2 (av. 0.29 wt%). Both pyroxenes appear before plagioclase in the crystallisation sequence, and therefore the Halmahera cumulate rocks are distinct from gabbroic rocks formed at mid-oceanic spreading ridges. The cumulus mineralogy is generally comparable with cumulates of the Papuan and Marum ophiolites of New Guinea and with cumulates dredged from the Mariana Trench; it is consistent with open-system crystalisation from a relatively high-Si, high-Mg, low-Ti magma derived from a high degree of partial melting of a lherzolitic mantle source. This correlates with the evidence from the harzburgites and suggests that the ophiolitic rocks were formed in a supra-subduction zone environment. The plutonic rocks are interpreted as resulting from approximately 20% melting of depleted oceanic upper mantle, triggered by

  3. Petrological features of the Santa Teresa Granitic Complex Southeastern Uruguay

    NASA Astrophysics Data System (ADS)

    Muzio, Rossana; Artur, Antonio Carlos

    1999-09-01

    The Santa Teresa Granitic Complex, located in the north-eastern region of the Rocha Department (Eastern Uruguay), is an epizonal Late-Brasiliano granite intruded in the low-grade metasedimentary sequence of the Rocha Group. Twelve different facies types, each with distinctive structural-petrographic features, were recognized during detailed mapping (1:50,000) of the central-eastern part of the granitic complex and form two magmatic suites. The Santa Teresa Calk-alkaline Suite is composed of mostly porphyritic 3a-3b granites with variable amounts of biotite, sphene, allanite, magnetite and microgranular enclaves and belongs to a middle to high potassium calk-alkaline series with high silica contents. In contrast, the Sierra de la Blanqueada Peraluminous Suite has a great variation of grain size, including 3a-3b granitic facies with variable content of muscovite, biotite, tourmaline, ilmenite and monazite. Zircon morphology was studied in both suites and also shows their calk-alkaline and peraluminous nature. The Santa Teresa Calk-alkaline Suite had a Late- to Post-orogenic setting whereas the Sierra de la Blanqueada Peraluminous Suite was formed during the crustal thickening related to a syn-collisional environment.

  4. Petrologic evolution of divergent peralkaline magmas from the Silent Canyon caldera complex, southwestern Nevada volcanic field

    USGS Publications Warehouse

    Sawyer, D.A.; Sargent, K.A.

    1989-01-01

    The Silent Canyon volcanic center consists of a buried Miocene peralkaline caldera complex and outlying peralkaline lava domes. Two widespread ash flow sheets, the Tub Spring and overlying Grouse Canyon members of the Miocene Belted Range Tuff, were erupted from the caldera complex and have volumes of 60-100 km3 and 200 km3, respectively. Eruption of the ash flows was preceded by widespread extrusion of precaldera comendite domes and was followed by extrusion of postcollapse peralkaline lavas and tuffs within and outside the caldera complex. Lava flows and tuffs were also deposited between the two major ash flow sheets. Rocks of the Silent Canyon center vary significantly in silica content and peralkalinity. Weakly peralkaline silicic comendites (PI 1.0-1.1) are the most abundant precaldera lavas. Postcollapse lavas range from trachyte to silicic comendite; some have anomalous light rare earth element (LREE) enrichments. Silent Canyon rocks follow a common petrologic evolution from trachyte to low-silica comendite; above 73% SiO2, compositions of the moderately peralkaline comendites diverge from those of the weakly peralkaline silicic comendites. The development of divergent peralkaline magmas, toward both pantelleritic and weakly peralkaline compositions, is unusual in a single volcanic center. -from Authors

  5. Metasedimentary melting in the formation of charnockite: Petrological and zircon U-Pb-Hf-O isotope evidence from the Darongshan S-type granitic complex in southern China

    NASA Astrophysics Data System (ADS)

    Jiao, Shu-Juan; Li, Xian-Hua; Huang, Hui-Qing; Deng, Xi-Guang

    2015-12-01

    Charnockites are Opx-bearing igneous rocks commonly found in high-grade metamorphic terranes. Despite being volumetrically minor, they show a wide range in both bulk geochemistry and intensive parameters. They form a characteristic component of the AMCG (anorthosite-mangerite-charnockite-granite) suite, but their association with typical S-type granites is less well-known. The Darongshan S-type granitic complex (DSGC) in Guangxi Province, southern China, contains granites varying in mafic silicate mineral assemblages from Bt + Crd (Darongshan suite) to Opx + Grt + Bt + Crd (Jiuzhou suite) and Opx + Crd ± Bt (Taima suite), corresponding to a geochemical transition from magnesian calc-alkalic to ferroan calc-alkalic. However, its genesis, even the accurate age of intrusion, remains highly contentious despite intensive research. In order to understand the genesis of charnockite and its genetic relationship with S-type granite; here, we first determined zircon U-Pb ages of each suite using a SIMS on the basis of a detailed petrological study. Zircon U-Pb ages show that all suites of the complex were emplaced contemporaneously at ca. 249 Ma. Monazite apparent U-Pb ages are indistinguishable from zircon U-Pb ages within analytical error. Further in situ zircon Hf-O isotope analyses reveal that the granitic complex was dominantly derived from reduced melting metasedimentary rocks (δ18Ozircon = ca. 11‰; εHf(t)zircon = ca. - 10; Δlog FMQ ≤ 0; Mn in apatite oxybarometer) with rare material input from the mantle. The variation in δ18O (7.8‰-12.9‰) is more likely a result of hybridization, whereas that in εHf(t) (- 31.9 to - 1.8) is a result of both hybridization and disequilibrium melting. The variation in mineralogy and geochemistry may be interpreted as a result of entrainment of peritectic garnets from biotite-dehydration melting. Nevertheless, heat input from mantle through basaltic intrusion/underplating is considered to play a major role in high

  6. Petrologic evolution of divergent peralkaline magmas from the Silent Canyon Caldera Complex, Southwestern Nevada Volcanic Field

    NASA Astrophysics Data System (ADS)

    Sawyer, David A.; Sargent, K. A.

    1989-05-01

    The Silent Canyon volcanic center consists of a buried Miocene peralkaline caldera complex and outlying peralkaline lava domes. Its location has been corroborated by geophysical data and more than 50 drill holes. Two widespread ash flow sheets, the Tub Spring and overlying Grouse Canyon members of the Miocene Belted Range Tuff, were erupted from the caldera complex and have volumes of 60-100 km3 and 200 km3, respectively. Eruption of the ash flows was preceded by widespread extrusion of precaldera comendite domes and was followed by extrusion of postcollapse peralkaline lavas and tuffs within and outside the caldera complex. Lava flows and tuffs were also deposited between the two major ash flow sheets. Rocks of the Silent Canyon center vary significantly in silica content and peralkalinity. The most mafic rocks are precollapse and postcollapse trachytes (65-69% SiO2). Low-silica comendites (69-73% SiO2) were erupted as the mafic upper part of the chemically zoned Grouse Canyon Member and as postcollapse lavas. The lower part of the Grouse Canyon Member and the underlying rhyolite of Split Ridge are moderately peralkaline comendite (PI is molar ratio Na + K/Al is 1.17-1.26). These comendites have major element characteristics and trace element enrichments approaching those of pantellerites. The Tub Spring Member, by contrast, is a weakly peralkaline chemically unzoned silicic comendite (75-76% SiO2) ash flow tuff. Weakly peralkaline silicic comendites (PI 1.0-1.1) are the most abundant precaldera lavas. Postcollapse lavas range from trachyte to silicic comendite; some have anomalous light rare earth element (LREE) enrichments. Silent Canyon rocks follow a common petrologic evolution from trachyte to low-silica comendite; above 73% SiO2, compositions of the moderately peralkaline comendites diverge from those of the weakly peralkaline silicic comendites. These contrasting differentiation paths are shown in the behavior of Fe and other transition metals, Al, Na, K

  7. The Mount Manengouba, a complex volcano of the Cameroon Line: Volcanic history, petrological and geochemical features

    NASA Astrophysics Data System (ADS)

    Pouclet, André; Kagou Dongmo, Armand; Bardintzeff, Jacques-Marie; Wandji, Pierre; Chakam Tagheu, Pulchérie; Nkouathio, David; Bellon, Hervé; Ruffet, Gilles

    2014-09-01

    The volcanic story of Mount Manengouba is related to four chronological stages: (1) forming of the early Manengouba shield volcano between 1.55 and 0.94 Ma, (2) building of the Eboga strato-cone between 0.94 and 0.89 Ma, (3) caldera collapse and silicic extrusions of the Elengoum Complex between 0.89 and 0.70 Ma, and (4) intra-caldera and flank activity between 0.45 and 0.11 Ma. The volume of the volcano is calculated at 320 km3 ± 5%. The volcanic rocks are attributed to two magmatic outputs. The first and main magma generation produced the shield volcano, the strato-cone, and the syn- to post-caldera extrusions, displaying a complete series from basanites to trachytes (magmatic Group 1). The second magma generation is limited to the late and flank activity evolving from basanites to trachy-phonolite (magmatic Group 2). Both magmatic groups belong to the under-saturated alkaline sodic series. Petrological calculations locate the magmatic reservoir between 37 and 39 km in the upper mantle for the Group 1 lavas, and between 42 and 44 km for the Group 2 lavas. Trachytes were generated in a secondary crustal reservoir. Magmatic series evolve with medium to low pressure fractional crystallization of olivine, pyroxene, oxides, feldspar, and apatite. Significant crustal assimilation is evidenced in trachytes. The magma of Group 1 was generated with 3-6% of partial melting of a moderately enriched source containing 3-7% of garnet. Melting took place in the spinel to garnet transition zone located at 70-90 km and around 25 kb. The magma of Group 2 resulted from a slightly higher partial melting from a less garnet-rich source that indicates uprising of the melting column in the upper part of transition zone. Sr, Nd, and Pb isotope data of the Manengouba rocks and neighboring lavas are analyzed and compared with those of the mafic lavas of the CVL. Three source components are distinguished: a depleted component originated from the asthenospheric swell, a radiogenic component

  8. Petrology, geochemistry and genesis of newly discovered Mesoproterozoic highly magnesian, calcite-rich kimberlites from Siddanpalli, Eastern Dharwar Craton, Southern India: products of subduction-related magmatic sources?

    NASA Astrophysics Data System (ADS)

    Chalapathi Rao, N. V.; Dongre, A.; Kamde, G.; Srivastava, Rajesh K.; Sridhar, M.; Kaminsky, F. V.

    2010-03-01

    The Siddanpalli kimberlites constitute a newly discovered cluster (SKC) of Mesoproterozoic (1090 Ma) dykes occurring in the granite-greenstone terrain of the Gadwal area in the Eastern Dharwar Craton (EDC), Southern India. They belong to coherent facies and contain serpentinized olivines (two generations), phlogopite, spinel, perovskite, ilmenite, apatite, carbonate and garnet xenocrysts. A peculiar feature of these kimberlites is the abundance of carbonate and limestone xenoliths of the eroded platformal Proterozoic (Purana) sedimentary cover of Kurnool/Bhima age. Chemically, the Siddanpalli dykes are the most magnesium-rich (up to 35 wt.% MgO) and silica-undersaturated (SiO2 < 35 wt.%) of all kimberlites described so far from the Eastern Dharwar Craton. The La/Yb ratio in the Siddanpalli kimberlites (64-105) is considerably lower than that in the other EDC kimberlites (108-145), primarily owing to their much higher HREE abundances. Since there is no evidence of any crustal contamination by granitic rocks we infer this to be a specific character of the magmatic source. A comparison of the REE geochemistry of the Siddanpalli kimberlites with petrogenetic models for southern African kimberlites suggests that they display involvement of a wide range in the degree of melting in their genesis. The different geochemical signatures of the SKC compared to the other known kimberlites in the EDC can be explained by a combination of factors involving: (i) higher degrees of partial melting; (ii) relatively shallower depths of derivation; (iii) possible involvement of subducted component in their mantle source region; and (iv) previous extraction of boninitic magmas from their geological domain.

  9. Molecular Chemistry in a Zeolite: Genesis of a Zeolite Y-Supported Ruthenium Complex Catalyst

    SciTech Connect

    Ogino, I.; Gates, B.C.

    2009-05-22

    Dealuminated zeolite Y was used as a crystalline support for a mononuclear ruthenium complex synthesized from cis-Ru(acac){sub 2}(C{sub 2}H{sub 4}){sub 2}. Infrared (IR) and extended X-ray absorption fine structure spectra indicated that the surface species were mononuclear ruthenium complexes, Ru(acac)(C{sub 2}H{sub 4}){sub 2}{sup 2+}, tightly bonded to the surface by two Ru-O bonds at Al{sup 3+} sites of the zeolite. The maximum loading of the anchored ruthenium complexes was one complex per two Al{sup 3+} sites; at higher loadings, some of the cis-Ru(acac){sub 2}(C{sub 2}H{sub 4}){sub 2} was physisorbed. In the presence of ethylene and H{sub 2}, the surface-bound species entered into a catalytic cycle for ethylene dimerization and operated stably. IR data showed that at the start of the catalytic reaction, the acac ligand of the Ru(acac)(C{sub 2}H{sub 4}){sub 2}{sup 2+} species was dissociated and captured by an Al{sup 3+} site. Ethylene dimerization proceeded 600 times faster with a cofeed of ethylene and H{sub 2} than without H{sub 2}. These results provide evidence of the importance of the cooperation of the Al{sup 3+} sites in the zeolite and the H{sub 2} in the feed for the genesis of the catalytically active species. The results presented here demonstrate the usefulness of dealuminated zeolite Y as a nearly uniform support that allows precise synthesis of supported catalysts and detailed elucidation of their structures.

  10. UNIT, PETROLOGY.

    ERIC Educational Resources Information Center

    Louisiana Arts and Science Center, Baton Rouge.

    THIS TEACHER'S GUIDE FOR A UNIT ON PETROLOGY IS SUITABLE FOR ADAPTATION AT EITHER THE UPPER ELEMENTARY OR THE JUNIOR HIGH SCHOOL LEVELS. THE UNIT BEGINS WITH A STORY THAT INTRODUCES VOLCANIC ACTION AND IGNEOUS ROCK FORMATION. SELECTED CONCEPTS ARE LISTED FOLLOWED BY SUGGESTED ACTIVITIES. A BIBLIOGRAPHY, FILM LIST, VOCABULARY LIST, AND QUESTION AND…

  11. Numerical modeling and analysis of the effect of Greek complex topography on tornado genesis

    NASA Astrophysics Data System (ADS)

    Matsangouras, I. T.; Pytharoulis, I.; Nastos, P. T.

    2014-02-01

    Tornadoes have been reported in Greece over the last decades in specific sub-geographical areas and have been associated with strong synoptic forcing. It is well known that meteorological conditions over Greece are affected at various scales by the significant variability of topography, the Ionian Sea at the west and the Aegean Sea at the east. However, there is still uncertainty regarding topography's importance on tornadic generation and development. The aim of this study is to investigate the role of topography in significant tornado genesis events that were triggered under strong synoptic scale forcing over Greece. Three tornado events that occurred over the last years in Thiva (Boeotia, 17 November 2007), Vrastema (Chalkidiki, 12 February 2010) and Vlychos (Lefkada, 20 September 2011) have been selected for numerical experiments. These events were associated with synoptic scale forcing, while their intensity was T4-T5 (Torro scale) and caused significant damage. The simulations were performed using the non-hydrostatic Weather Research and Forecasting model (WRF), initialized with ECMWF gridded analyses, with telescoping nested grids that allow the representation of atmospheric circulations ranging from the synoptic scale down to the meso scale. In the experiments the topography of the inner grid was modified by: (a) 0% (actual topography) and (b) -100% (without topography). The aim was to determine whether the occurrence of tornadoes - mainly identified by various severe weather instability indices - could be indicated by modifying topography. The main utilized instability variables concerned the Bulk Richardson number shear (BRN), the energy helicity index (EHI), the storm-relative environmental helicity (SRH) and the maximum convective available potential energy (MCAPE, for parcel with maximum theta-e). Additional a verification of model was conducted for every sensitivity experiment accompanied with analysis absolute vorticity budget. Numerical simulations

  12. Petrology and chemistry of Jebel Tanumah complex, Khamis Mushayt, Southern Arabian shield, Saudi Arabia

    NASA Astrophysics Data System (ADS)

    Nassief, M. O.; Ali, H. M.; Zakir, F. A.

    The mafic intrusive complex at Jebel Tanumah is located 15 km north-west of Khamis Mushayt in the southern Arabian Shield and includes olivine-bearing gabbro as well as amphibole-diopside-hornblende gabbro cumulates. These rocks have been generally metamorphosed to upper greeenschist-lower amphibolite facies. Fourteen white rock silicate analyses indicate that the majority of the rocks are calc-alkaline to tholeiitic in composition. The two major structural units in the Khamis Mushayt region identified by Coleman consist of the basement complex of Asir Mountains and the younger metamorphic rocks. Syntectonic granitic rocks intruded the antiforms characterizing the younger rocks whereas the lower parts of the synforms are intruded by post-tectonic intrusions of layered gabbros such as the one studied at Jebel Tanumah.

  13. Petrology, geochemistry, and geochronology of trondhjemites from the Qori Complex, Neyriz, Iran

    NASA Astrophysics Data System (ADS)

    Fazlnia, Abdolnaser; Schenk, Volker; van der Straaten, François; Mirmohammadi, Mirsaleh

    2009-10-01

    Metamorphism, magmatism, and thrusting were the result of subduction of Neotethys beneath the continental-margin arc of the Sanandaj-Sirjan shear zone (SSSZ) during the Mesozoic. The Qori metamorphic complex is a part of the southern SSSZ. Leuco-granitic (trondhjemitic) rocks crop out in the Qori metamorphic complex and are rare rock types in the SSSZ. These rocks have intruded into the marbles and garnet amphibolites, the highest grade metamorphic rocks of the Qori metamorphic complex, and in some outcrops, a transitional boundary between the amphibolites and the granitoids can be distinguished. The granitoids are granular in texture and consist of plagioclase (albite-oligoclase), quartz ± K-feldspar ±muscovite and subordinate garnet, spinel, rutile, and apatite which primarily occur as inclusions in the main phases. The peraluminous trondhjemitic rocks are enriched in Na 2O and SiO 2 and depleted in FeO, MgO, and CaO. Similarities with some trondhjemitic liquids produced through partial melting of amphibolites or hydrous basalts (i.e., low-Al 2O 3 content, less than 15 wt.%; low Ba, Sr, TiO 2, and Eu content, all with negative anomalies; moderately enriched LREEs and Y, and flat HREE patterns) suggest that the evolution of the parental magma was controlled by residual plagioclases during partial melting of a garnet amphibolite source. Concentrations of ferromagnesian elements, Mg, Fe, and Mn, are low, suggesting that the granitic rocks were not produced by high degrees of partial melting. Furthermore, they display low amounts of ferromagnesian components from the protolith (garnet amphibolite). This is supported by consideration of compatible elements, especially Cr, Ni and Ti (and the less robust HREE), which respectively show very high and high bulk partition coefficients for relatively small degrees (< 20%) of partial melting of the source. The partial melting of the garnet amphibolites occurred at pressures and temperatures between 7.5 and 9.5 kbar (at a

  14. Magnetic fabrics and petrology of the Newry Igneous Complex, Northern Ireland reveals a new emplacement model

    NASA Astrophysics Data System (ADS)

    Anderson, Paul; Stevenson, Carl; Cooper, Mark; Ellam, Rob; Meighan, Ian; Hurley, Colm; Reavy, John; Inman, James; Condon, Dan; Crowley, Quentin

    2013-04-01

    The Newry Igneous Complex (NIC) is a largely granodioritic intrusion, comprising three plutons together with an intermediate-ultramafic body at its NE end. The recent Tellus survey of Northern Ireland has highlighted several geophysical anomalies within this area, including two previously unrecognised concentric aeromagnetic structures. U-Pb zircon ages and a geochemical study suggest that these features represent magmas intruded at different times, and that each pluton was emplaced through a series of inward-younging, concentric pulses. A combination of anisotropy of magnetic susceptibility (AMS) and field relations were used to investigate the emplacement of these pulses. AMS reveals strong, dominantly oblate, concentric fabrics. These suggest forceful emplacement. Field relationships indicate that the complex was intruded as steep, sheet-like pulses. Host rocks show deflection of fabrics around the NIC supporting the forceful emplacemnt model. However the amount of strain recorded in the host rocks does not fully explain the space required for intrusion. The presence of a deeply penetrating tectontic structure offers a way to transport magma and create space through a releasing bend. The releasing bend would have created some of the space for intrusion to take place initially and likely guided the ascent of magma. However, the strong fabrics present within the NIC suggest that most of the space for the intrusion was created in a forceful way. Therefore, the NIC was emplaced as a ballooning type pluton after ascent through a tectonically created conduit along a deeply penetrating fault.

  15. Petrogenesis of the Sabongari alkaline complex, cameroon line (central Africa): Preliminary petrological and geochemical constraints

    NASA Astrophysics Data System (ADS)

    Njonfang, Emmanuel; Tchoneng, Gilbert Tchuenté; Cozzupoli, Domenico; Lucci, Federico

    2013-07-01

    The petrography, mineral chemistry and geochemical features of the Sabongari alkaline complex are presented and discussed in this paper with the aim of constraining its petrogenesis and comparing it with other alkaline complexes of the Cameroon Line. The complex is mainly made up of felsic rocks: (i) granites predominate and include pyroxene-amphibole (the most abundant), amphibole-biotite, biotite and pyroxene types; (ii) syenites are subordinate and comprise amphibole-pyroxene and amphibole-biotite quartz syenites; (iii) pyroxene-amphibole-biotite trachyte and (iv) relatively abundant rhyolite. The minor basic and intermediate terms associated with felsic rocks consist of basanites, microdiorite and monzodioites. Two groups of pyroxene bearing rocks are distinguished: a basanite-trachyte-granite (Group 1) bimodal series (SiO2 gap: 44 and 63 wt.%) and a basanite-microdiorite-monzodiorite-syenite-granite (Group 2) less pronounced bimodal series (reduced SiO2 gap: 56-67 wt.%). Both are metaluminous to peralkaline whereas felsic rocks bare of pyroxene (Group 3) are metaluminous to peraluminous. The Group 1 basanite is SiO2-undersaturated (modal analcite in the groundmass and 11.04 wt.% normative nepheline); its Ni (240 ppm) and Cr (450 ppm) contents, near mantle values, indicate its most primitive character. The Group 2 basanite is rather slightly SiO2-saturated (1.56 wt.% normative hypersthene), a marker of its high crustal contamination (low Nb/Y-high Rb/Y). The La/Yb and Gd/Yb values of both basanites (1: 19.47 and 2.92; 2: 9.09 and 2.23) suggest their common parental magma composition, and their crystallization through two episodes of partial melting (2% and 3% respectively) of a lherzolite mantle source with <4% residual garnet. The effects of crustal contamination were selectively felt in the values of HFSE/LREE, LREE/LILE and LREE/HFSE ratios, known as indicators. Similar features have been recently obtained in the felsic lavas of the Cameroon Volcanic Line.

  16. Petrological and geochemical constraints on granitoid formation: The Waldoboro Pluton Complex, Maine

    SciTech Connect

    Barton, M. . Dept. of Geological Science); Sidle, W.S. )

    1992-01-01

    The Waldoboro Pluton Complex (WPC) comprises seven units ranging from qtz-diorite to aplite. The country rocks are biotite-rich metagraywackes with minor shales mostly belonging to the Proterozoic Z-Ordovician Bucksport Formation. Field evidence strongly suggests that the WPC formed in-situ: contacts with the country rock are cryptic, transitional and concordant; restitic minerals in the granitoids are identical to those in the country rocks; prolific metasedimentary enclaves in the WPC are locally derived. Major and trace element data for country rock and the most voluminous units of the WPC define consistent linear trends suggesting limited melt segregation and retention of a high proportion of restite. Mixing models and partial melting models require 54--76% melting for generation of the gneissic granites and two-mica granites. Garnet-biotite geothermometry and garnet-Al[sub 2]SiO[sub 5]-SiO[sub 2]-plagioclase geobarometry indicate that the WPC formed at T = 740--780 C and P = 0.4--0.7 GPa. Published experimental data show that < 50% melting is likely under these conditions if melting is controlled by dehydration reactions. Bucksport lithologies contain < 20% biotite, suggesting that the maximum amount of melt that could have formed by dehydration melting is < 20%, even if all biotite was consumed during melting. It seems probable that a free fluid phase was required to generate the WPC. Migmatization is apparent in all lithologies (including amphibolites) in the vicinity of the WPC, consistent with fluid-present melting. Fluid may have ingressed along the St. George thrust, but the source of the fluid is unknown.

  17. Petrology of a Neoproterozoic Alaskan-type complex from the Eastern Desert of Egypt: Implications for mantle heterogeneity

    NASA Astrophysics Data System (ADS)

    Khedr, Mohamed Zaki; Arai, Shoji

    2016-10-01

    This paper details petrological and geochemical studies of an ultramafic-mafic intrusion in the Southern Eastern Desert of Egypt. The Dahanib complex shows a concentric zonation, from dunites at the core, through chromitites, clinopyroxene-rich dunites, wehrlites, harzburgites, gabbronorites and layered gabbros, to hornblende gabbros/diorites at the rim, similar to other Alaskan-type complexes. These lithologies typically feature cumulate textures and layering. Their pyroxenes (Mg#s, 0.54-0.94) evidence Fe, Mn and Na enrichment, but Al, Cr, Mg and Ti are depleted with differentiation. Their chromian spinels have a wide range of Cr# (0.31-0.61), along with high Ti and Fe, as a result of their origin through crystal accumulation and reaction with interstitial liquids. The clinopyroxenes (Cpxs) in peridotites and gabbroic rocks, which are high in REE concentration (2-100 times chondrite), are depleted in LREE relative to HREE and are similar to Cpx crystallized from asthenospheric melts. The mineral inclusions in spinel, the chemistry of Cpx in peridotites (rich in Al, Cr, Na, Ti and ΣREE = 13.7), and the melts in equilibrium with Cpx suggest that the Neoproterozoic lithosphere were partially refertilized by trace asthenospheric melts. The early magmas were possibly enriched by Mg, Cr, Ni, Ti, V and Sr, while the evolved types were rich in Fe, Mn, Na, Li, Zr, Co and REE via crystal accumulation and the interaction with interstitial liquids. The Neoproterozoic sub-arc mantle in Egypt is chemically heterogeneous and generally low in Nb, Ta, Zr and K, due to the low solubility of HFSE in slab-derived fluids and no other external addition of these elements. The large variations in lithology and chemistry, as well as the occurrence of scattered chromitite clots in the Dahanib peridotites, are related to a continuous supply of primitive magmas and/or the reaction between interstitial liquids and early cumulus crystals during multistage fractional crystallization. The

  18. Petrology, geochemistry and geochronology of the magmatic suite from the Jianzha Complex, central China: Petrogenesis and geodynamic implications

    NASA Astrophysics Data System (ADS)

    Li, Xiaowei; Mo, Xuanxue; Bader, Thomas; Scheltens, Mark; Yu, Xuehui; Dong, Guochen; Huang, Xiongfei

    2014-12-01

    The intermediate-mafic-ultramafic rocks in the Jianzha Complex (JZC) at the northern margin of the West Qinling Orogenic Belt have been interpreted to be a part of an ophiolite suite. In this study, we present new geochronological, petrological, geochemical and Sr-Nd-Hf isotopic data and provide a different interpretation. The JZC is composed of dunite, wehrlite, olivine clinopyroxenite, olivine gabbro, gabbro, and pyroxene diorite. The suite shows characteristics of Alaskan-type complexes, including (1) the low CaO concentrations in olivine; (2) evidence of crystal accumulation; (3) high calcic composition of clinopyroxene; and (4) negative correlation between FeOtot and Cr2O3 of spinels. Hornblende and phlogopite are ubiquitous in the wehrlites, but minor orthopyroxene is also present. Hornblende and biotite are abundant late crystallized phases in the gabbros and diorites. The two pyroxene-bearing diorite samples from JZC yield zircon U-Pb ages of 245.7 ± 1.3 Ma and 241.8 ± 1.3 Ma. The mafic and ultramafic rocks display slightly enriched LREE patterns. The wehrlites display moderate to weak negative Eu anomalies (0.74-0.94), whereas the olivine gabbros and gabbros have pronounced positive Eu anomalies. Diorites show slight LREE enrichment, with (La/Yb)N ratios ranging from 4.42 to 7.79, and moderate to weak negative Eu anomalies (Eu/Eu∗ = 0.64-0.86). The mafic and ultramafic rocks from this suite are characterized by negative Nb-Ta-Zr anomalies as well as positive Pb anomalies. Diorites show pronounced negative Ba, Nb-Ta and Ti spikes, and typical Th-U, K and Pb peaks. Combined with petrographic observations and chemical variations, we suggest that the magmatism was dominantly controlled by fractional crystallization and crystal accumulation, with limited crustal contamination. The arc-affinity signature and weekly negative to moderately positive εNd(t) values (-2.3 to 1.2) suggest that these rocks may have been generated by partial melting of the juvenile

  19. Petrology of the Motaghairat mafic-ultramafic complex, Eastern Desert, Egypt: A high-Mg post-collisional extension-related layered intrusion

    NASA Astrophysics Data System (ADS)

    Abdel Halim, Ali H.; Helmy, Hassan M.; Abd El-Rahman, Yasser M.; Shibata, Tomoyuki; El Mahallawi, Mahmoud M.; Yoshikawa, Masako; Arai, Shoji

    2016-02-01

    The geodynamic settings of the Precambrian mafic-ultramafic complexes in the Eastern Desert of Egypt have important bearing on understanding the geotectonic evolution of the Arabian Nubian Shield. We present a detailed petrological study on a layered mafic-ultramafic intrusion that is located at the contact between the Precambrian continental crust and the Miocene Red Sea oceanic crust. The Motaghairat layered intrusion consists of basal lherzolite, orthopyroxenite, troctolite, olivine gabbro and anorthosite on the top. Variations in modal mineralogy and mineral chemistry along with the chemical composition of these units suggest their derivation from a common high-Mg tholeiitic parent melt through fractional crystallization processes. The parental magma was derived from a metasomatised mantle source. The primitive mantle-normalized patterns of the calculated melts exhibit enrichment in U relative to Th and Ba relative LREE which indicate that the enriched lithospheric mantle source was metasomatised by fluids derived from a subducted oceanic crust rather than by a sediment melt. Geological and petrological evidences suggest that the layered Motaghairat intrusion was emplaced during post-orogenic extension following subduction break-off and lithospheric delamination after the collision between the amalgamated island arc terranes and the Saharan Metacraton. The heat source required to melt the metasomatised lithospheric mantle was derived from the upwelling of hot asthenosphere after the subduction-break-off.

  20. Transient Spectroscopic Characterization of the Genesis of a Ruthenium Complex Catalyst Supported on Zeolite Y

    SciTech Connect

    Ogino, Isao; Gates, Bruce C.

    2010-01-12

    A mononuclear ruthenium complex anchored to dealuminated zeolite HY, Ru(acac)(C{sub 2}H{sub 4}){sup 2+} (acac = acetylacetonate, C{sub 5}H{sub 7}O{sup 2}{sup -}), was characterized in flow reactors by transient infrared (IR) spectroscopy and Ru K edge X-ray absorption spectroscopy. The combined results show how the supported complex was converted into a form that catalyzes ethene conversion to butene. The formation of these species resulted from the removal of acac ligands from the ruthenium (as shown by IR and extended X-ray absorption fine structure (EXAFS) spectra) and the simultaneous decrease in the symmetry of the ruthenium complex, with the ruthenium remaining mononuclear and its oxidation state remaining essentially unchanged (as shown by EXAFS and X-ray absorption near-edge structure spectra). The removal of anionic acac ligands from the ruthenium was evidently compensated by the bonding of other anionic ligands, such as hydride from H2 in the feed stream, to form species suggested to be Ru(H)(C{sub 2}H{sub 4}){sub 2}{sup +}, which is coordinatively unsaturated and inferred to react with ethene, leading to the observed formation of butene in a catalytic process.

  1. Foliated breccias in the active Portuguese Bend landslide complex, California: bearing on melange genesis

    SciTech Connect

    Larue, D.K.; Hudleston, P.J.

    1987-05-01

    The active portion of the Portuguese Bend landslide complex is approximately 3 km/sup 2/ in area and 30-50 m thick. Measured displacement rates range from less than one to greater than 30 mm/day on different parts of the landslide, with total displacements over the last 30 yrs ranging from about 10 to greater than 150 m. Six types of breccia, each locally with a foliated matrix, were recognized in the active landslide complex and are absent outside the landslide complex. Slide-body breccias are of two types, the first formed by extensional fracturing during bulk pure shear at the top of the landslide (slide-top breccia) and the second by flow of tuffaceous shales and fracture of embedded siliceous shales during simple shear deep in the landslide to the basal decollement (slide-bottom breccias). Slide-margin breccias, also in simple shear, are produced on the lateral margins of individual slide blocks accompanying wrench-fault motion. Other breccias (fault-ramp breccias) are formed during motion over ramps. Colluvial deposits within tension gashes (crack-fill breccias) and at the toe of the slide (slide-toe breccias) represent a fifth breccia type. Diapirs originating from over-pressured zones at the slide base also contain breccia. Recognition of different breccia types in ancient rocks would be difficult, because fabrics in the different types are similar. Foliations are defined by: scaly cleavage, compositional banding and color banding (in shear zones), stretched mud clasts, and aligned hard grains. Foliated breccias are synonymous with melanges. The authors regard the six breccia types described herein as representing the principal types of melange that occur in ancient accretionary settings.

  2. Congenital nystagmus: hypotheses for its genesis and complex waveforms within a behavioral ocular motor system model.

    PubMed

    Jacobs, Jonathan B; Dell'Osso, Louis F

    2004-07-27

    Attempts to simulate dysfunction within ocular motor system (OMS) models capable of exhibiting known ocular motor behavior have provided valuable insight into the structure of the OMS required for normal visual function. The pendular waveforms of congenital nystagmus (CN) appear to be quite complex, composed of a sustained sinusoidal oscillation punctuated by braking saccades and foveating saccades followed by periods of extended foveation. Previously, we verified that these quick phases are generated by the same mechanism as voluntary saccades. We propose a computer model of the ocular motor system that simulates the responses of individuals with pendular CN (including its variable waveforms) based on the instability exhibited by the normal pursuit subsystem and its interaction with other components of the normal ocular motor control system. Fixation data from subjects with CN using both infrared and magnetic search coil oculography were used as templates for our simulations. Our OMS model simulates data from individuals with CN during fixation and in response to complex stimuli. The use of position and velocity efference copy to suppress oscillopsia is the key element in allowing for normal ocular motor behavior. The model's responses to target steps, pulse-steps, ramps, and step-ramps support the hypothetical explanation for the conditions that result in sustained pendular oscillation and the rules for the corrective saccadic responses that shape this underlying oscillation into the well-known family of pendular CN waveforms: pendular (P), pseudopendular (PP), pendular with foveating saccades (Pfs), and pseudopendular with foveating saccades (PPfs). Position error determined the saccadic amplitudes of foveating saccades, whereas stereotypical braking saccades were not dependent on visual information. Additionally, we propose a structure and method of operation for the fixation subsystem, and use it to prolong the low-velocity intervals immediately following

  3. Petrology and geochemistry of Abyssal Peridotites from the Manipur Ophiolite Complex, Indo-Myanmar Orogenic Belt, Northeast India: Implication for melt generation in mid-oceanic ridge environment

    NASA Astrophysics Data System (ADS)

    Krishnakanta Singh, A.

    2013-04-01

    The Manipur Ophiolite Complex (MOC) located in the Indo-Myanmar Orogenic Belt (IMOB) of Northeast India forms a section of the Tethyan Ophiolite Belt of the Alpine-Himalayan orogenic system. Whole rock compositions and mineral chemistry of mantle peridotites from the MOC show an affinity to the abyssal peridotites, characterized by high contents of Al2O3 (1.28-3.30 anhydrous wt.%); low Cr# of Cr-spinel (0.11-0.27); low Mg# of olivine (˜Fo90) and high Al2O3 in pyroxenes (3.71-6.35 wt.%). They have very low REE concentrations (∑REE = 0.48-2.14 ppb). Lherzolites display LREE-depleted patterns (LaN/SmN = 0.14-0.45) with a flat to slightly fractionated HREE segments (SmN/YbN = 0.30-0.65) whereas Cpx-harburgites have flat to upward-inflected LREE patterns (LaN/SmN = 0.13-1.23) with more fractionated HREE patterns (SmN/YbN = 0.13-0.65) than the lherzolite samples. Their platinum group elements (PGE) contents (<50 ppb) and distinct mantle-normalised PGE patterns with the Pd/Ir values (1.8-11.9) and Pt/Pt* values (0.2-1.1) show an affinity to the characteristic of the residual mantle material. Evaluation of mineralogical and petrological characteristics of these peridotites suggests that they represent the residues remaining after low degree of partial melting (˜2-12%) in the spinel stability field of a mid-oceanic ridge environment. The well-preserved mid-oceanic ridge characteristics of these peridotites further suggest that the mantle section was subsequently trapped in the forearc region of the subduction zone without undergoing significant modification in their chemistry by later subduction-related tectonic and petrological processes before its emplacement to the present crustal level.

  4. Geophysical and petrological modelling of the structure and composition of the crust and upper mantle in complex geodynamic settings: The Tyrrhenian Sea and surroundings

    NASA Astrophysics Data System (ADS)

    Panza, G. F.; Peccerillo, A.; Aoudia, A.; Farina, B.

    2007-01-01

    Information on the physical and chemical properties of the lithosphere-asthenosphere system (LAS) can be obtained by geophysical investigation and by studies of petrology-geochemistry of magmatic rocks and entrained xenoliths. Integration of petrological and geophysical studies is particularly useful in geodynamically complex areas characterised by abundant and compositionally variable young magmatism, such as in the Tyrrhenian Sea and surroundings. A thin crust, less than 10 km, overlying a soft mantle (where partial melting can reach about 10%) is observed for Magnaghi, Vavilov and Marsili, which belong to the Central Tyrrhenian Sea backarc volcanism where subalkaline rocks dominate. Similar characteristics are seen for the uppermost crust of Ischia. A crust about 20 km thick is observed for the majority of the continental volcanoes, including Amiata-Vulsini, Roccamonfina, Phlegraean Fields-Vesuvius, Vulture, Stromboli, Vulcano-Lipari, Etna and Ustica. A thicker crust is present at Albani - about 25 km - and at Cimino-Vico-Sabatini — about 30 km. The structure of the upper mantle, in contrast, shows striking differences among various volcanic provinces. Volcanoes of the Roman region (Vulsini-Sabatini-Alban Hills) sit over an upper mantle characterised by Vs mostly ranging from about 4.2 to 4.4 km/s. At the Alban Hills, however, slightly lower Vs values of about 4.1 km/s are detected between 60 and 120 km of depth. This parallels the similar and rather homogeneous compositional features of the Roman volcanoes, whereas the lower Vs values detected at the Alban Hills may reflect the occurrence of small amounts of melts within the mantle, in agreement with the younger age of this volcano. The axial zone of the Apennines, where ultrapotassic kamafugitic volcanoes are present, has a mantle structure with high-velocity lid ( Vs ˜ 4.5 km/s) occurring at the base of a 40-km-thick crust. Beneath the Campanian volcanoes of Vesuvius and Phlegraean Fields, the mantle

  5. Assessment of Petrological Microscopes.

    ERIC Educational Resources Information Center

    Mathison, Charter Innes

    1990-01-01

    Presented is a set of procedures designed to check the design, ergonomics, illumination, function, optics, accessory equipment, and image quality of a microscope being considered for purchase. Functions for use in a petrology or mineralogy laboratory are stressed. (CW)

  6. Influence of contrasting aspect, lithology, and vegetation on saprolite genesis in complex terrain: Reynolds Creek Critical Zone Observatory

    NASA Astrophysics Data System (ADS)

    Klos, P. Z.; Link, T. E.; Durrett, W.; Heinse, R.; Seyfried, M. S.; Leonard, E. M.

    2014-12-01

    This study employs a variety of geophysical, biological, hydrological, and pedological methods to expand on the understanding of how contrasting aspects, lithologies, and vegetation influence critical zone structure and evolution. We performed shallow seismic refraction (SSR) and time-lapse electrical resistivity tomography (ERT) surveys across two geologically distinct valleys within the Reynolds Creek Critical Zone Observatory in southwestern Idaho. We also quantified vegetation density, soil pH, and subsurface stratigraphy (by manual sampling) across opposing north-facing (forested) and south-facing (unforested) aspects to better understand the relationship between lithology, vegetation, seasonal moisture dynamics, and saprolite genesis within the critical zone. The first study sub-site, Upper Johnston Draw, resides on late Cretaceous granitic bedrock associated with the Idaho Batholith. The second study sub-site, Upper Sheep Creek, resides on Miocene basaltic bedrock. In the granitic Upper Johnston Draw there is a sharp contrast in depth to unweathered bedrock (regolith thickness) between the north-facing aspect (average depth of 18.6 m) and the south-facing aspect (average depth of 8.2 m). In the basaltic Upper Sheep Creek there is only a marginal contrast in depth to unweathered bedrock between the north-facing aspect (average depth of 14.4 m) and the south-facing aspect (average depth of 12.0 m). These observed relationships between the contrasting lithologies of Upper Johnston Draw and Upper Sheep Creek, coupled with our time-lapse ERT surveys, vegetation density tests, soil pH tests, and subsurface augering data, provide new understanding about the causes of symmetry or asymmetry in saprolite development on north-facing and south-facing slopes. Specifically, these findings suggest that abiotic chemical weathering via hydrolysis may be the dominant control creating the symmetrical pattern of saprolite genesis (north vs. south aspects) observed within the

  7. The Beginnings of Experimental Petrology

    ERIC Educational Resources Information Center

    Eugster, Hans P.

    1971-01-01

    An account of Van't Hoff's change from theoretical chemistry to petrology provides data on the European intellectual climate of the early 1900's and shows how his work laid the foundation for experimental petrology of hard rocks." (AL)

  8. Phlogopite- and clinopyroxene-dominated fractional crystallization of an alkaline primitive melt: petrology and mineral chemistry of the Dariv Igneous Complex, Western Mongolia

    NASA Astrophysics Data System (ADS)

    Bucholz, Claire E.; Jagoutz, Oliver; Schmidt, Max W.; Sambuu, Oyungerel

    2014-04-01

    We present field relationships, petrography, and mineral major and trace element data for the Neoproterozoic Dariv Igneous Complex of the Altaids of Western Mongolia. This unique complex of high-K plutonic rocks is composed of well-exposed, km-scale igneous intrusions of wehrlites, phlogopite wehrlites, apatite-bearing phlogopite clinopyroxenites, monzogabbros, monzodiorites, and clinopyroxene-bearing monzonites, all of which are intruded by late stage lamprophyric and aplitic dikes. The biotite-dominated igneous complex intrudes depleted harzburgitic serpentinite. The observed lithological variability and petrographic observations suggest that the plutonic rocks can be ascribed to a fractionation sequence defined by olivine + clinopyroxene ± Fe-Ti oxides → phlogopite + apatite → K-feldspar + plagioclase → amphibole + quartz. Notably, phlogopite is the dominant hydrous mafic mineral. Petrogenesis of the observed lithologies through a common fractionation sequence is supported by a gradual decrease in the Mg# [molar Mg/(Fetotal + Mg) × 100] of mafic minerals. Crystallization conditions are derived from experimental phase petrology and mineral chemistry. The most primitive ultramafic cumulates crystallized at ≤0.5 GPa and 1,210-1,100 °C and oxygen fugacity ( fO2) of +2-3 ∆FMQ (log units above the fayalite-quartz-magnetite buffer). Trace element modeling using clinopyroxene and apatite rare earth element compositions indicates that the dominant mechanism of differentiation was fractional crystallization. The trace element composition of a parental melt was calculated from primitive clinopyroxene compositions and compares favorably with the compositions of syn-magmatic lamprophyres that crosscut the fractionation sequence. The parental melt composition is highly enriched in Th, U, large ion lithophile elements, and light rare earth elements and has a pronounced negative Nb-Ta depletion, suggestive of an alkaline primitive melt originating from a subduction

  9. Garnet-biotite diffusion mechanisms in complex high-grade orogenic belts: Understanding and constraining petrological cooling rates in granulites from Ribeira Fold Belt (SE Brazil)

    NASA Astrophysics Data System (ADS)

    Bento dos Santos, Telmo M.; Tassinari, Colombo C. G.; Fonseca, Paulo E.

    2014-12-01

    Cooling rates based on the retrograde diffusion of Fe2+ and Mg between garnet and biotite inclusions commonly show two contrasting scenarios: a) narrow closure temperature range with apparent absence of retrograde diffusion; or b) high result dispersion due to compositional variations in garnet and biotite. Cooling rates from migmatites, felsic and mafic granulites from Ribeira Fold Belt (SE Brazil) also show these two scenarios. Although the former can be explained by very fast cooling, the latter is often the result of open-system behaviour caused by deformation. Retrogressive cooling during the exhumation of granulite-facies rocks is often processed by thrusting and shearing which may cause plastic deformation, fractures and cracks in the garnet megablasts, allowing chemical diffusion outside the garnet megablast - biotite inclusion system. However, a careful use of garnets and biotites with large Fe/Mg variation and software that reduces result dispersion provides a good correlation between closure temperatures and the size of biotite inclusions which are mostly due to diffusion and compositional readjustment to thermal evolution during retrogression. Results show that felsic and mafic granulites have low cooling rates (1-2 °C/Ma) at higher temperatures and high cooling rates (˜100 °C/Ma) at lower temperatures, suggesting a two-step cooling/exhumation process, whereas migmatites show a small decrease in cooling rates during cooling (from 2.0 to 0.5 °C/Ma). These results agree with previously obtained thermochronological data, which indicates that this method is a valid tool to obtain meaningful petrological cooling rates in complex high-grade orogenic belts, such as the Ribeira Fold Belt.

  10. Petrology and mineral equilibrium modeling of incipient charnockite from the Lützow-Holm Complex, East Antarctica: implications for granulite formation in a Gondwana fragment

    NASA Astrophysics Data System (ADS)

    Tsunogae, Toshiaki

    2015-04-01

    Charnockite (orthopyroxene-bearing granitoid) is regarded as one of the fundamental lithologies in many high-grade metamorphic terranes including Neoproterozoic collisional orogen formed during the amalgamation of Gondwana supercontinent. Although both magmatic (massive) and metamorphic charnockites have been reported, several classic examples for the spectacular development of 'incipient charnockites' within orthopyroxene-free felsic gneisses are exposed in several quarry sections in Neoproterozoic granulite terrenes in southern India (e.g., Trivandrum Block) and Sri Lanka. (e.g., Wanni Complex). The charnockite-forming process in these localities is considered to have been triggered by the infiltration of CO2-rich anhydrous fluids along structural pathways within upper amphibolite facies gneisses, resulting in the lowering of water activity and stabilization of orthopyroxene through the breakdown of biotite. However, no detailed study of incipient charnockites in the Lützow-Holm Complex of East Antarctica, which is regarded as an extension of Neoproterozoic to Cambrian orogeny in India and Sri Lanka, has been reported so far. This study thus reports new petrological data of incipient charnockite patches in orthopyroxene-free felsic gneiss from Skallevikshalsen in the granulite-facies region of the Lützow-Holm Complex, East Antarctica, and discuss the timing and process of charnockite formation. Incipient charnockite (Opx + Qtz + Pl + Kfs + Grt) occurs as dark brownish patches of several cm in length within coarse-grained leucocratic gneiss (Qtz + Pl + Kfs + Grt) interlayered with various supracrustal lithologies such as mafic granulite, pelitic granulite, and marble. Orthopyroxene, which occurs only in garnet-bearing portion of the rock, probably formed by a FMAS continuous reaction: Grt + Qtz => Opx + Pl. Phase equilibrium modeling in the system NCKFMASH suggests a wide range of P-T stability (>780 C, >6 kbar), although the condition is broadly consistent with

  11. Stratigraphy, petrology, and geochemistry of the Spurr Volcanic Complex, eastern Aleutian Arc, Alaska. [(Appendix for geothermal fluid chemistry)

    SciTech Connect

    Nye, C.J.

    1987-12-01

    The Spurr Volcanic Complex (SVC) is a calcalkaline, medium-K, sequence of andesites erupted over the last quarter of a million years by the easternmost currently active volcanic center in the Aleutian Arc. The ancestral Mt. Spurr was built mostly of andesites of uniform composition (58 to 60% SiO/sub 2/), although andesite production was episodically interrupted by the introduction of new batches of more mafic magma. Near the end of the Pleistocene the ancestral Mt. Spurr underwent Bezyianny-type avalanche caldera formation, resulting in the production of a volcanic debris avalanche with overlying ashflows. Immediately afterward, a large dome (the present Mt. Spurr) was emplaced in the caldera. Both the ashflows and dome are made of acid andesite more silicic than any analyzed lavas from the ancestral Mt. Spurr (60 to 63% SiO/sub 2/), yet contain olivine and amphibole xenocrysts derived from more mafic magma. The mafic magma (53 to 57% SiO/sub 2/) erupted during and after dome emplacement, forming proto-Crater Peak and Crater Peak. Hybrid pyroclastic flows and lavas were also produced. Proto-Crater Peak underwent glacial dissection prior to the formation of Crater Peak in approximately the same location. Appendices II through VIII contain a summary of mineral compositions; Appendix I contains geochemical data. Appendix IX by R.J. Motyka and C.J. Nye describes the chemistry of geothermal fluids. 78 refs., 16 figs., 3 tabs.

  12. Petrology and geochemistry of ultrapotassic rocks from the Montefiascone Volcanic Complex (Central Italy): magmatic evolution and petrogenesis

    NASA Astrophysics Data System (ADS)

    Di Battistini, G.; Montanini, A.; Vernia, L.; Bargossi, G. M.; Castorina, F.

    1998-07-01

    The Montefiascone Volcanic Complex belongs to the Roman Magmatic Province of Central Italy; the volcanic activity took place in an extensional, post-collisional setting during Late Pleistocene, giving rise to lava flows and pyroclastic deposits. The extrusive products consist of moderately to strongly undersaturated K-rich lavas ranging in composition from trachybasalts through leucite basanites and leucititic tephrites to tephritic leucitites. They show the typical geochemical and isotopic characters of the Roman potassic magmas, i.e., low TiO 2, low K 2O/Al 2O 3, strong enrichment in LILE, high LILE/HFSE ratios, highly radiogenic 87Sr/ 86Sr ratios (0.71005-0.71112) and unradiogenic 143Nd/ 144Nd (0.51209-0.51229, corresponding to ɛNd=-10.7 to -6.8). Large chemical variations have been recognized within the Montefiascone volcanics, resulting both from the occurrence of different primary magmas and shallow-level fractionation processes. The differentiation mainly took place by means of closed-system fractional crystallisation with local influence of crustal assimilation. The leucite basanites represent primary mantle magmas which did not yield derivative products, whereas the leucititic tephrites, tephritic leucitites and trachybasalts comprise highly differentiated rocks strongly depleted in compatible elements and enriched in LILE. Fractional crystallisation dominated respectively by clinopyroxene+leucite and clinopyroxene+plagioclase yielded the most evolved tephritic leucitites and trachybasalts. In contrast, assimilation of metamorphic basement rocks characterized by highly radiogenic 87Sr/ 86Sr is needed to explain the moderate increase of the 87Sr/ 86Sr ratio within the leucititic tephrites. The geochemical and isotopic signatures shown by the Montefiascone primary magmas require a clinopyroxene- and phlogopite-rich mantle source; in particular, partial melting of a veined lithospheric mantle can account for the occurrence of different primary magmas

  13. Petrology of the Guenfalabo ring-complex: An example of a complete series along the Cameroon Volcanic Line (CVL), Cameroon

    NASA Astrophysics Data System (ADS)

    Donald Ngonge, E.; Hollanda, Maria Helena B. M.; Nsifa, E. Nkonguin; Tchoua, Felix M.

    2014-08-01

    In the Guenfalabo ring-complex (GRC), two non-comagmatic rock suites have been identified as a result of two volcanic episodes: Suite 1 (68.8 ± 1.7 Ma by K/Ar on trachyte) of peralkaline trachytes and pantellerites cogenetic with alkaline syenites, granites and rhyolitic flows and tuffs; Suite 2 (62 ± 2 Ma by K/Ar on basalt), a bimodal and complete series of alkali olivine basalts and associated microgabbro dykes, diorites, syenites and granites, cross-cutting the former. Kaersutite in the trachytes of Suite 1 has mantle-derived signatures: TiO2 > 4%, MgO < 15%, FeO > 8%, Ti = 0.63 c.p.f.u. and Al = 2, characteristic of kaersutites of HP and HT origin: 13-23 kbar, 1100-1220 °C. The trachytes are probably products of FC of a basaltic parent that did not attain higher crustal levels. The Suite 1 rocks are enriched in Rb, K, Zr, Nb, LREE, alkalis, and (Ce/Yb)N = 7-15 probably due to some effect of metasomatism during the magma ascension. Fe-Ti enrichment is corroborated by the presence of ferropseudobrookite-ilmenite-ulvospinel in the syenites and ilmenite in the pantellerite. The Rb/Ba > 1 in the trachytes (2.44, 26.7), pantellerite (6.33), alkaline granites (0.63-1.8) and the 87Sr/86Sr in the alkaline granites (=0.74060) depict the role of AFC. The ankaramites of the Suite 2 rocks are olivine-phyric (25%), Fo85-88, have 50-52% clinopyroxene (salite), 5% plagioclase (An55-36) and 7% Fe-Ti oxides. Trace element modeling indicates an origin from a basaltic magma of about 25% PM of spinel lherzolite mixed with a magma from <1% PM of garnet lherzolite (3-4% garnet) in a proportion of 1:4. The cogenetic alkali basalts and the microgabbro-diorite-syenite-granite that constitute the Suite 2 rocks, with a Daly gap of 54% > SiO2 < 58%, result from this Early Cenozoic magmatic event. The basalts have: Zr = 225-253, Nb = 98-111, Y = 33-56, typical of FOZO, a HIMU-type OIB related magmas (Sr/Sri = 0.70202-0.7034; Nd/Nd = 0.51282-0.512545; 206Pb/204Pb = 19.13, 207Pb/204Pb = 15

  14. Geology, petrology and geochronology of the Lago Grande layered complex: Evidence for a PGE-mineralized magmatic suite in the Carajás Mineral Province, Brazil

    NASA Astrophysics Data System (ADS)

    Teixeira, Antonio Sales; Ferreira Filho, Cesar Fonseca; Giustina, Maria Emilia Schutesky Della; Araújo, Sylvia Maria; da Silva, Heloisa Helena Azevedo Barbosa

    2015-12-01

    ultramafic lithotypes render Nd model ages between 2.94 and 3.56 Ga, with variably negative ɛNd (T = 2.72 Ga) values (-0.32 to -4.25). The crystallization sequence of the intrusion and the composition of cumulus minerals, together with lithogeochemical and Nd isotopic results, are consistent with an original mantle melt contaminated with older continental crust. The contamination of mafic magma with sialic crust is also consistent with intra-plate rifting models proposed in several studies of the CMP. Lithogeochemical and isotopic data from the Lago Grande Complex may also be interpreted as the result of melting an old lithospheric mantle, and alternative models should not be disregarded. PGE mineralizations occur in chromitites and associated with base metal sulfides in the Lago Grande Complex. Chromitite has the highest PGE content (up to 10 ppm) and is characterized by high Pt/Pd ratio (4.3). Mantle-normalized profile of chromitite is highly enriched in PPGE and similar to those from Middle Group (MG) and Upper Group (UG) chromitites from the Bushveld Complex. Platinum group minerals (PGM) occur mainly at the edge of chromite crystals in the Lago Grande chromitite, consisting of arsenides and sulfo-arsenides. Sulfide-bearing harzburgite samples of the Lago Grande complex have PGE content of up to 1 ppm and low Pt/Pd (0.2-0.3) ratios. The 2722 ± 53 Ma U-Pb zircon age determined in this study for the Lago Grande Complex overlaps with the crystallization age of the Luanga Complex. Previous interpretation that the Lago Grande and Luanga layered intrusions are part of a magmatic suite (i.e., Serra Leste Magmatic Suite) is now reinforced by similar fractionation sequences, comparable petrological evolution and overlapped U-Pb zircon ages. The occurrence of the same styles of PGE mineralization in the Lago Grande and Luanga complexes, together with remarkably similar chondrite-normalized PGE profiles and PGE minerals for chromitites of both complexes, support the concept that

  15. Petrologic and Chemical Characterization of a Suite of Antarctic Diogenites

    NASA Technical Reports Server (NTRS)

    Mittlefehldt, D. W.; Mertzman, S. A.; Peng, Z. X.; Mertzman, K. R.

    2013-01-01

    The origin of diogenites, ultramafic cumulates related to eucrites, is an unresolved problem [1]. Most diogenites are orthopyroxenites, a few are harzburgites [2], and some are transitional to cumulate eucrites [1, 3]. Cumulate eucrites are gabbros formed by crystal fractionation from basaltic eucrites [4]. The consensus view is that basaltic eucrites are residual melts from global-magma-ocean crystallization on their parent asteroid [4] which is plausibly Vesta [5]. However, the petrologic and compositional characteristics of diogenites seem to preclude a magma ocean origin [1, 4]. We are doing a petrologic and chemical study of new or unusual diogenites with the ultimate goals of constraining their genesis, and the geologic evolution of Vesta.

  16. Petrology of Anomalous Eucrites

    NASA Technical Reports Server (NTRS)

    Mittlefehldt, D. W.; Peng, Z. X.; Ross, D. K.

    2015-01-01

    Most mafic achondrites can be broadly categorized as being "eucritic", that is, they are composed of a ferroan low-Ca clinopyroxene, high-Ca plagioclase and a silica phase. They are petrologically distinct from angritic basalts, which are composed of high-Ca, Al-Ti-rich clinopyroxene, Carich olivine, nearly pure anorthite and kirschsteinite, or from what might be called brachinitic basalts, which are composed of ferroan orthopyroxene and high-Ca clinopyroxene, intermediate-Ca plagioclase and ferroan olivine. Because of their similar mineralogy and composition, eucrite-like mafic achondrites formed on compositionally similar asteroids under similar conditions of temperature, pressure and oxygen fugacity. Some of them have distinctive isotopic compositions and petrologic characteristics that demonstrate formation on asteroids different from the parent of the HED clan (e.g., Ibitira, Northwest Africa (NWA) 011). Others show smaller oxygen isotopic distinctions but are otherwise petrologically and compositionally indistinguishable from basaltic eucrites (e.g., Pasamonte, Pecora Escarpment (PCA) 91007). The degree of uniformity in delta O-17 of eucrites and diogenites is one piece of evidence considered to favor of a magma-ocean scenario for their petrogenesis. Given that the O isotopic differences separating Pasamonte and PCA 91007 from other eucrites are small, and that there is an absence of other distinguishing characteristics, a legitimate question is: Did the HED parent asteroid fail to homogenize via a magma-ocean stage, thus explaining outliers like Pasamonte? We are initiating a program of study of anomalous eucrite-like achondrites as one part of our effort to seek a resolution of this issue. Here we present preliminary petrologic information on Asuka (A-) 881394, Elephant Moraine (EET) 87520 and EET 87542. We will have studied several more by conference time.

  17. Polymetamorphic evolution of the upper part of the Iezer Complex (Leaota Massif, South Carpathians) constrained by petrological data and monazite ages

    NASA Astrophysics Data System (ADS)

    Negulescu, Elena; Săbău, Gavril; Massonne, Hans-Joachim

    2015-04-01

    The Leaota Massif in Romania consists of a flat-lying sequence of five structurally concordant units displaying mutual and partly internal lithologic and metamorphic contrasts. The lower part of the lithologic sequence is the Iezer Complex, a medium-grade psammopelitic unit with a structurally concordant thin granite sill located at its upper part. The lower limit of the granite is marked discontinuously by hornfels, also present as enclaves, which experienced intense strain and a subsequent low-pressure thermal overprint. Both granite and hornfels were affected by a medium-temperature, medium- to high-pressure event (Săbău, 2000). This event was also identified in gneisses below the hornfels. These rocks contain the assemblage garnet-phengite-chloritoid-kyanite which had overprinted an older garnet-kyanite-staurolite-biotite-muscovite assemblage. Available U-Th zircon ages indicate 472.7 ± 7.3 Ma (Balintoni et al. 2009) for the granite. Monazite geochronology (Săbău & Negulescu, 2013) reveals for the associated hornfels (1) inherited ages of 528 ± 17.86 Ma overprinted by pervasive Ordovician contact metamorphism (462 ± 4.54 Ma), slightly postdating the age of magmatic zircon in the granite, (2) Silurian to Early Devonian recrystallization episodes, and (3) a Variscan medium- to high-pressure metamorphic overprint responsible for the garnet-phengite-kyanite assemblage. New petrological and geochronological data constraining the polymetamorphic evolution of the upper part of the Iezer Complex were acquired from kyanite-garnet mylonitic gneisses made up of large garnet porphyroclasts embedded in a strongly deformed matrix. Large garnets are rich in quartz, phengite, epidote, kyanite, rutile, and ilmenite inclusions. Biotite, chlorite, apatite, monazite, and Al-cerite inclusions are also present. Garnet porphyroclasts are wrapped by laminae of small garnet - white mica - biotite - quartz or zoisite - kyanite - plagioclase alternating with bands made up of fine

  18. Petrology of blueschist from the Western Himalaya (Ladakh, NW India): Exploring the complex behavior of a lawsonite-bearing system in a paleo-accretionary setting

    NASA Astrophysics Data System (ADS)

    Groppo, Chiara; Rolfo, Franco; Sachan, Himanshu K.; Rai, Santosh K.

    2016-05-01

    Although the Himalaya is the archetype of collisional orogens, formed as a consequence of the closure of the Neo-Tethyan ocean separating India from Asia, high-pressure metamorphic rocks are rare. Beside few eclogites, corresponding to the metamorphosed continental Indian crust dragged below Asia or underthrusted beneath southern Tibet, blueschists occur seldom along the Yarlung-Tsangpo Suture zone, i.e. the suture marking the India-Asia collision. These blueschists, mostly interpreted as related to paleo-accretionary prisms formed in response to the subduction of the Neo-Tethyan ocean below the Asian plate, are crucial for constraining the evolution of the India-Asia convergence zone during the closure of the Neo-Tethyan Ocean. In the Western Himalaya, the best occurrence of blueschist is that of the Sapi-Shergol Ophiolitic Mélange in Ladakh. This unit is dominated by volcanoclastic sequences rich in mafic material with subordinate interbedding of metasediments, characterized by very fresh lawsonite blueschist-facies assemblages. In this paper, the lawsonite blueschist-facies metasediments have been petrologically investigated with the aims of (i) constraining the P-T evolution of the Sapi-Shergol Ophiolitic Mélange, (ii) evaluating the influence of Fe2O3 and of H2O on the stability of the high-pressure mineral assemblages, (iii) understanding the processes controlling lawsonite formation and preservation, and (iv) interpreting the P-T evolution of the Sapi-Shergol blueschists in the framework of India-Asia collision. Our results indicate that (i) the Sapi-Shergol blueschists experienced a cold subduction history along a low thermal gradient, up to peak conditions of ca. 470 °C, 19 kbar; furthermore, in order to preserve lawsonite in the studied lithologies, exhumation must have been coupled with significant cooling, i.e. the resulting P-T path is characterized by a clockwise hairpin loop along low thermal gradients (< 8-9 °C/km); (ii) the presence of ferric

  19. Genesis and evolution of mafic and felsic magmas at Quaternary volcanoes within the Main Ethiopian Rift: Insights from Gedemsa and Fanta 'Ale complexes

    NASA Astrophysics Data System (ADS)

    Giordano, F.; D'Antonio, M.; Civetta, L.; Tonarini, S.; Orsi, G.; Ayalew, D.; Yirgu, G.; Dell'Erba, F.; Di Vito, M. A.; Isaia, R.

    2014-02-01

    This paper presents the results of an investigation carried out on young volcanic rocks from the Gedemsa and Fanta 'Ale complexes, located in the Main Ethiopian Rift, the site of an intense magmatism since Eocene-Oligocene. The earlier NW-SE direction of extension of the Rift, which generated NE-SW trending faults, rotated around E-W in Quaternary times, and produced the still active N to N-NE Wonji Fault System. The Gedemsa volcano is located in the central part of the Ethiopian Rift, about 100 km SE of Addis Ababa. It is characterized by a wide central caldera, about 8 km in diameter. The general stratigraphic sequence in the area includes, from base upwards, rift-floor ignimbrites, pantelleritic and subordinate trachytic pyroclastic deposits and lava flows and domes, and widespread basaltic deposits. The Fanta 'Ale volcanic complex is located in the northern part of the Main Ethiopian Rift, where the Afar depression begins. It is characterized by a summit caldera of which the diameter is about 4 km. This volcano erupted trachytic and rhyolitic lavas, whereas the most diffuse unit is an ignimbrite related to the caldera collapse. Explosive activity has occurred inside and outside the caldera, forming tuff cones and thick pumice-fallout deposits. The only mafic unit is represented by a basaltic eruption that occurred in 1870 AD. Historical eruptions and intense fumarolic activity are evidence for the persistence activity of the Fanta 'Ale in this part of the Main Ethiopian Rift. New geochemical and Sr-Nd-Pb isotope data on representative samples from Gedemsa and Fanta 'Ale volcanoes are presented and discussed in order to shed light on the genesis of mafic and felsic magmas, the genetic link between them, and their possible interaction with the local crust. Volcanic rocks show a typical mafic-felsic bi-modal distribution with few intermediate terms (Daly Gap), as observed at regional scale along the Main Ethiopian Rift as well as on the plateau. Geochemical data

  20. Petrology of mafic and ultramafic intrusions from the Portneuf-Mauricie Domain, Grenville Province, Canada: Implications for plutonic complexes in a Proterozoic island arc

    NASA Astrophysics Data System (ADS)

    Sappin, A.-A.; Constantin, M.; Clark, T.

    2012-12-01

    The Portneuf-Mauricie Domain (PMD), located in the south-central part of the Grenville Province, comprises several mafic and ultramafic intrusions hosting Ni-Cu ± platinum-group element (PGE) prospects and a former small mining operation (Lac Édouard mine). These meter- to kilometer-scale, sulfide-bearing intrusions display diverse forms, such as layered and tabular bodies with no particular internal structure, and zoned plutons. They were injected ~ 1.40 Ga into a mature oceanic arc, before and during accretion of the arc to the Laurentian margin. The pressure-temperature conditions of the magmas at the beginning of their emplacement were 3 kbar and 1319-1200 °C (according to the petrologic modeling results from this study). The PMD mineralized intrusions are interpreted to represent former magma chambers or magma conduits in the roots of the oceanic arc. The parent magmas of the mineralized intrusions resulted mainly from the partial melting of a mantle source composed of spinel-bearing lherzolite. Petrologic modeling and the occurrence of primary amphibole in the plutonic rocks indicate that these parent melts were basaltic and hydrous. In addition, fractional crystallization modeling and Mg/Fe ratios suggest that most of the intrusions may have formed from evolved magmas, with Mg# = 60, resulting from the fractionation of more primitive magmas (primary magmas, with Mg# = 68). Petrologic modeling demonstrates that 30% fractional crystallization resulted in the primitive to evolved characteristics of the studied intrusive rocks (as indicated by the crystallization sequences and mineral chemistry). Exceptions are the Réservoir Blanc, Boivin, and Rochette West parent magmas, which may have undergone more extensive fractional crystallization, since these intrusions contain pyroxenes that are more iron rich and have lower Mg numbers than pyroxenes in the other PMD intrusions. The PMD mafic and ultramafic intrusions were intruded into an island arc located

  1. Genesis of emulsion texture due to magma mixing: a case study from Chotanagpur Granite Gneiss Complex of Eastern India

    NASA Astrophysics Data System (ADS)

    Gogoi, Bibhuti; Saikia, Ashima; Ahmad, Mansoor

    2016-04-01

    The emulsion texture is a rare magma mixing feature in which rounded bodies of one magmatic phase remain dispersed in the other coherent phase (Freundt and Schmincke, 1992). This type of special texture in hybrid rocks can significantly contribute toward understanding the mechanisms facilitating magma mixing and magma chamber dynamics involving two disparate magmas as the exact processes by which mixing occurs still remain unclear. Recent developments in microfluidics have greatly helped us to understand the complex processes governing magma mixing occurring at micro-level. Presented work uses some of the results obtained from microfluidic experiments with a view to understand the formation mechanism of emulsions preserved in the hybrid rocks of the Ghansura Rhyolite Dome (GRD) of Proterozoic Chotanagpur Granite Gneiss Complex (CGGC), Eastern India. The GRD has preserved hybrid rocks displaying emulsion texture that formed due to the interaction of a phenocryst-rich basaltic magma and host rhyolite magma. The emulsions are more or less spherical in shape and dominantly composed of amphibole having biotite rinds set in a matrix of biotite, plagioclase, K-feldspar and quartz. Amphibole compositions were determined from the core of the emulsions to the rim with a view to check for cationic substitutions. The amphibole constituting the emulsions is actinolite in composition, and commonly shows tschermakite (Ts) and pargasite (Prg) substitutions. From petrographical and mineral-chemical analyses we infer that when mafic magma, containing phenocrysts of augite, came in contact with felsic magma, diffusion of cations like H+, Al3+and others occurred from the felsic to the mafic system. These cations reacted with the clinopyroxene phenocrysts in the mafic magma to form amphibole (actinolite) crystals. The formation of amphibole crystals in the mafic system greatly increased the viscosity of the system allowing the amphibole crystals to venture into the adjacent felsic

  2. Genesis Failure Investigation Report

    NASA Technical Reports Server (NTRS)

    Klein, John

    2004-01-01

    The-Genesis mission to collect solar-wind samples and return them to Earth for detailed analysis proceeded successfully for 3.5 years. During reentry on September 8, 2004, a failure in the entry, descent and landing sequence resulted in a crash landing of the Genesis sample return capsule. This document describes the findings of the avionics sub-team that supported the accident investigation of the JPL Failure Review Board.

  3. Genesis of supported carbon-coated Co nanoparticles with controlled magnetic properties, prepared by decomposition of chelate complexes

    NASA Astrophysics Data System (ADS)

    Tarasov, Konstantin; Beaunier, Patricia; Che, Michel; Marceau, Eric; Li, Yanling

    2011-05-01

    Following procedures formerly developed for the preparation of supported heterogeneous catalysts, carbon-coated cobalt nanoparticles dispersed on porous alumina have been prepared by impregnation of γ-Al2O3 with (NH4)2[Co(EDTA)] and thermal decomposition in inert atmosphere. Below 350 °C, Co(II) ions are complexed in a hexa-coordinated way by the EDTA ligand. The thermal treatment at 400-900 °C leads to the EDTA ligand decomposition and recovering of the support porosity, initially clogged by the impregnated salt. According to X-ray absorption spectroscopy, and due to in situ redox reactions between the organic ligand and Co(II), both oxidic and metallic cobalt phases are formed. Characterisation by transmission electron microscopy, X-ray diffraction and magnetic measurements reveals that an increase in the treatment temperature leads to an increase of the degree of cobalt reduction as well as to a growth of the cobalt metal particles. As a consequence, the samples prepared at 400-700 °C exhibit superparamagnetism and a saturation magnetisation of 1.7-6.5 emu g-1 at room temperature, whilst the sample prepared at 900 °C has a weak coercivity (0.1 kOe) and a saturation magnetisation of 12 emu g-1. Metal particles are homogeneously dispersed on the support and appear to be protected by carbon; its elimination by a heating in H2 at 400 °C is demonstrated to cause sintering of the metal particles. The route investigated here can be of interest for obtaining porous magnetic adsorbents or carriers with high magnetic moments and low coercivities, in which the magnetic nanoparticles are protected from chemical aggression and sintering by their coating.

  4. Petrology, geochemistry and zircon U-Pb geochronology of a layered igneous complex from Akarui Point in the Lützow-Holm Complex, East Antarctica: Implications for Antarctica-Sri Lanka correlation

    NASA Astrophysics Data System (ADS)

    Kazami, Sou; Tsunogae, Toshiaki; Santosh, M.; Tsutsumi, Yukiyasu; Takamura, Yusuke

    2016-11-01

    The Lützow-Holm Complex (LHC) of East Antarctica forms part of a complex subduction-collision orogen related to the amalgamation of the Neoproterozoic supercontinent Gondwana. Here we report new petrological, geochemical, and geochronological data from a metamorphosed and disrupted layered igneous complex from Akarui Point in the LHC which provide new insights into the evolution of the complex. The complex is composed of mafic orthogneiss (edenite/pargasite + plagioclase ± clinopyroxene ± orthopyroxene ± spinel ± sapphirine ± K-feldspar), meta-ultramafic rock (pargasite + olivine + spinel + orthopyroxene), and felsic orthogneiss (plagioclase + quartz + pargasite + biotite ± garnet). The rocks show obvious compositional layering reflecting the chemical variation possibly through magmatic differentiation. The metamorphic conditions of the rocks were estimated using hornblende-plagioclase geothermometry which yielded temperatures of 720-840 °C. The geochemical data of the orthogneisses indicate fractional crystallization possibly related to differentiation within a magma chamber. Most of the mafic-ultramafic samples show enrichment of LILE, negative Nb, Ta, P and Ti anomalies, and constant HFSE contents in primitive-mantle normalized trace element plots suggesting volcanic arc affinity probably related to subduction. The enrichment of LREE and flat HREE patterns in chondrite-normalized REE plot, with the Nb-Zr-Y, Y-La-Nb, and Th/Yb-Nb/Yb plots also suggest volcanic arc affinity. The felsic orthogneiss plotted on Nb/Zr-Zr diagram (low Nb/Zr ratio) and spider diagrams (enrichment of LILE, negative Nb, Ta, P and Ti anomalies) also show magmatic arc origin. The morphology, internal structure, and high Th/U ratio of zircon grains in felsic orthogneiss are consistent with magmatic origin for most of these grains. Zircon U-Pb analyses suggest Early Neoproterozoic (847.4 ± 8.0 Ma) magmatism and protolith formation. Some older grains (1026-882 Ma) are regarded as

  5. Generalized galilean genesis

    SciTech Connect

    Nishi, Sakine; Kobayashi, Tsutomu

    2015-03-31

    The galilean genesis scenario is an alternative to inflation in which the universe starts expanding from Minkowski in the asymptotic past by violating the null energy condition stably. Several concrete models of galilean genesis have been constructed so far within the context of galileon-type scalar-field theories. We give a generic, unified description of the galilean genesis scenario in terms of the Horndeski theory, i.e., the most general scalar-tensor theory with second-order field equations. In doing so we generalize the previous models to have a new parameter (denoted by α) which results in controlling the evolution of the Hubble rate. The background dynamics is investigated to show that the generalized galilean genesis solution is an attractor, similarly to the original model. We also study the nature of primordial perturbations in the generalized galilean genesis scenario. In all the models described by our generalized genesis Lagrangian, amplification of tensor perturbations does not occur as opposed to what happens in quasi-de Sitter inflation. We show that the spectral index of curvature perturbations is determined solely from the parameter α and does not depend on the other details of the model. In contrast to the original model, a nearly scale-invariant spectrum of curvature perturbations is obtained for a specific choice of α.

  6. Generalized galilean genesis

    SciTech Connect

    Nishi, Sakine; Kobayashi, Tsutomu E-mail: tsutomu@rikkyo.ac.jp

    2015-03-01

    The galilean genesis scenario is an alternative to inflation in which the universe starts expanding from Minkowski in the asymptotic past by violating the null energy condition stably. Several concrete models of galilean genesis have been constructed so far within the context of galileon-type scalar-field theories. We give a generic, unified description of the galilean genesis scenario in terms of the Horndeski theory, i.e., the most general scalar-tensor theory with second-order field equations. In doing so we generalize the previous models to have a new parameter (denoted by α) which results in controlling the evolution of the Hubble rate. The background dynamics is investigated to show that the generalized galilean genesis solution is an attractor, similarly to the original model. We also study the nature of primordial perturbations in the generalized galilean genesis scenario. In all the models described by our generalized genesis Lagrangian, amplification of tensor perturbations does not occur as opposed to what happens in quasi-de Sitter inflation. We show that the spectral index of curvature perturbations is determined solely from the parameter α and does not depend on the other details of the model. In contrast to the original model, a nearly scale-invariant spectrum of curvature perturbations is obtained for a specific choice of α.

  7. Review and update of the applications of organic petrology: Part 2, geological and multidisciplinary applications

    USGS Publications Warehouse

    Suarez-Ruiz, Isabel; Flores, Deolinda; Mendonça Filho, João Graciano; Hackley, Paul C.

    2012-01-01

    The present paper is focused on organic petrology applied to unconventional and multidisciplinary investigations and is the second part of a two part review that describes the geological applications and uses of this branch of earth sciences. Therefore, this paper reviews the use of organic petrology in investigations of: (i) ore genesis when organic matter occurs associated with mineralization; (ii) the behavior of organic matter in coal fires (self-heating and self-combustion); (iii) environmental and anthropogenic impacts associated with the management and industrial utilization of coal; (iv) archeology and the nature and geographical provenance of objects of organic nature such as jet, amber, other artifacts and coal from archeological sites; and (v) forensic science connected with criminal behavior or disasters. This second part of the review outlines the most recent research and applications of organic petrology in those fields.

  8. The Petrology of Very Small Rocks

    NASA Astrophysics Data System (ADS)

    Valley, J. W.; Cavosie, A. J.

    2006-12-01

    A hallmark of Eric Essene`s research and teaching is to `look at your sample` before advanced analysis. We apply this common sense yet sometimes ignored advice to explore the relation between mineral inclusions within zircon and host rock type from 4 suites: two with known genesis and two that are uncertain. A wide range of techniques can be applied to "look" at zircons and their inclusions as the prelude to in situ isotopic, structural, and chemical analysis including: optics, acid etching, SEM (SE, CL, EDS, BSE, EBSD), cold cathode CL, SIMS, and X-ray mapping. Zircons from the Sierra Nevada batholith have granitic parentage, and contain polymineralic assemblages of quartz ± biotite ± K-feldspar ± plagioclase ± muscovite ± apatite ± Fe oxide ± sphene ± amphibole. Zircons from young ocean crust have gabbroic parentage, and contain plagioclase ± intergrown Fe-Ti oxides ± apatite ± amphibole ± clinopyroxene, and rarely contain quartz. The mantle suite of zircons from kimberlite is united by chemical and physical similarities, but occurs as xenocrysts of uncertain origin. They may contain euhedral tetragonal ZrO2 ± olivine ± clinopyroxene ± apatite, in cavities up to 100 microns long. Thus the kimberlite xenocrysts are consistent with mafic or ultramafic composition. Detrital zircons from the Jack Hills metaconglomerate range in age from 4.4 to 3.1 Ga and are also of uncertain genesis. Inclusions include common quartz ± apatite ± muscovite ± monazite ± rutile ± xenotime ± Fe-oxide ± Fe sulfide. The Jack Hills zircon inclusions, irrespective of age, indicate silica saturated magmas, are most similar to those in granitic rocks, and are distinctly different from zircons in mafic ocean crust, but this does not preclude formation in small volumes of evolved magma. The observation that zircon inclusions are in apparent equilibrium demonstrates that these inclusion assemblages carry petrologic information and can be studied as `small rocks`.

  9. Origin of rhythmic anorthositic-pyroxenitic layering in the Damiao anorthosite complex, China: Implications for late-stage fractional crystallization and genesis of Fe-Ti oxide ores

    NASA Astrophysics Data System (ADS)

    Li, Li-Xing; Li, Hou-Min; Li, Yong-Zhan; Yao, Tong; Yang, Xiu-Qing; Chen, Jing

    2015-12-01

    The ∼1.7 Ga Damiao anorthosite complex (DAC) in the North China Craton contains abundant Ti-magnetite-dominated ore deposits. Both the Fe-Ti-P-rich silicate rocks and massive Fe-Ti-(P) ores occur as discordant late-stage dikes cross-cutting early-stage anorthosites with irregular but sharp boundaries. Field and petrographic observations indicate that some late-stage dikes are composed of unique oxide-apatite gabbronorites (OAGNs), whereas others comprise well-developed alternating late-stage anorthosites and Fe-Ti-P-rich pyroxenites defining rhythmic layers. Massive Fe-Ti-(P) ores are closely related to the Fe-Ti-P-rich pyroxenites. Plagioclase and whole-rock compositions of different rock types were analyzed to constrain the late-stage magma evolution and genesis of the Fe-Ti oxide ores. The similar mineralogical assemblages, REE and HFSE patterns suggest that the different rock types formed by differentiation from a common parental magma. Early-stage anorthosites are characterized by positive Eu anomalies and low REE contents, whereas the late-stage dike-like rocks display no significant Eu anomalies and high REE contents. Plagioclase compositions in the late-stage rocks show a decrease of An contents when compared to that of the early-stage rocks. Based on field relations, petrography and well-defined linear compositional trends, the sequence of crystallization is inferred as: early-stage anorthosites + leuconorites + norites, OAGNs, late-stage anorthosites + Fe-Ti-P-rich pyroxenites + massive Fe-Ti-(P) ores, and massive Fe-Ti-(P) ores. The OAGNs which underwent relatively rapid crystallization represent an early phase during the residual magma evolution after anorthosite separation, whereas the rhythmic layers formed by slow but extensive fractional crystallization of interstitial melt. High solubility of phosphorous played an important role in the formation of rhythmic layering. Massive Fe-Ti-(P) ores crystallized and segregated directly from the magma of Fe

  10. Genesis Radiation Environment

    NASA Technical Reports Server (NTRS)

    Minow, Joseph I.; Altstatt, Richard L.; Skipworth, William C.

    2007-01-01

    The Genesis spacecraft launched on 8 August 2001 sampled solar wind environments at L1 from 2001 to 2004. After the Science Capsule door was opened, numerous foils and samples were exposed to the various solar wind environments during periods including slow solar wind from the streamer belts, fast solar wind flows from coronal holes, and coronal mass ejections. The Survey and Examination of Eroded Returned Surfaces (SEERS) program led by NASA's Space Environments and Effects program had initiated access for the space materials community to the remaining Science Capsule hardware after the science samples had been removed for evaluation of materials exposure to the space environment. This presentation will describe the process used to generate a reference radiation Genesis Radiation Environment developed for the SEERS program for use by the materials science community in their analyses of the Genesis hardware.

  11. Porting GENESIS to SIMULINK.

    PubMed

    Rodriguez Campos, Francisco; Enderle, John D

    2004-01-01

    This paper describes the porting of the general simulation system (GENESIS) to Matrix Language Laboratory language (MatLab) SIMULINK, based in the cable theory to simulate the behavior of neurons. A graphic programming approach serves as ideal platform for teaching physiological modeling and neuroengineering courses. The ultimate goal of this project is to integrate all of the chemical, electrical, material, mechanical and neural interactions into a single model that can be viewed seamlessly from a molecular model to the large scale model. Integration of all interactions is not possible with GENESIS, but can be accomplished with SIMULINK.

  12. How a complex basaltic volcanic system works: Constraints from integrating seismic, geodetic, and petrological data at Mount Etna volcano during the July-August 2014 eruption

    NASA Astrophysics Data System (ADS)

    Viccaro, Marco; Zuccarello, Francesco; Cannata, Andrea; Palano, Mimmo; Gresta, Stefano

    2016-08-01

    Integrating geodetic, seismic, and petrological data for a recent eruptive episode at Mount Etna has enabled us to define the history of magma storage and transfer within the multilevel structure of the volcano, providing spatial and temporal constraints for magma movements before the eruption. Geodetic data related to the July-August 2014 activity provide evidence of a magma reservoir at ~4 km below sea level. This reservoir pressurized from late March 2014 and fed magmas that were then erupted from vents on the lower eastern flank of North-East Crater (NEC) and at New South-East Crater (NSEC) summit crater during the July eruptive activity. Magma drainage caused its depressurization since mid-July. Textural and microanalytical data obtained from plagioclase crystals indicate similar disequilibrium textures and compositions at the cores in lavas erupted at the base of NEC and NSEC, suggesting comparable deep histories of evolution and ascent. Conversely, the compositional differences observed at the crystal rims have been associated to distinct degassing styles during storage in a shallow magma reservoir. Seismic data have constrained depth for a shallow part of the plumbing system at 1-2 km above sea level. Timescales of magma storage and transfer have also been calculated through diffusion modeling of zoning in olivine crystals of the two systems. Our data reveal a common deep history of magmas from the two systems, which is consistent with a recharging phase by more mafic magma between late March and early June 2014. Later, the magma continued its crystallization under distinct chemical and physical conditions at shallower levels.

  13. Journal of Mineralogical and Petrological Sciences

    NASA Astrophysics Data System (ADS)

    Official journal of Japan Association of Mineralogical Sciences (JAMS), focusing on mineralogical and petrological sciences and their related fields. Journal of Mineralogical and Petrological Sciences (JMPS) is the successor journal to both “Journal of Mineralogy, Petrology and Economic Geology” and “Mineralogical Journal”. Journal of Mineralogical and Petrological Sciences (JMPS) is indexed in the ISI database (Thomson Reuters), the Science Citation Index-Expanded, Current Contents/Physical, Chemical & Earth Sciences, and ISI Alerting Services.

  14. Genesis Field Recovery

    NASA Technical Reports Server (NTRS)

    McNamara, K. M.

    2005-01-01

    The Genesis mission returned to Earth on September 8, 2004 after a nearly flawless three-year mission to collect solar matter. The intent was to deploy a drogue chute and parafoil high over the Utah desert and to catch the fragile payload capsule in mid-air by helicopter. The capsule would then be opened in a clean-room constructed for that purpose at UTTR, and a nitrogen purge was to be installed before transporting the science canister to JSC. Unfortunately, both chutes failed to deploy, causing the capsule to fall to the desert floor at a speed of nearly 200 MPH. Still, Genesis represents a milestone in the US space program, comprising the first sample return since the Apollo Missions as well as the first return of materials exposed to the space environment outside of low Earth orbit and beyond the Earth s magnetosphere for an extended period. We have no other comparable materials in all of our collections on Earth. The goal of the Genesis Mission was to collect a representative sample of the composition of the solar wind and thus, the solar nebula from which our solar system originated. This was done by allowing the naturally accelerated species to implant shallowly in the surfaces of ultra-pure, ultra-clean collector materials. These collectors included single crystal silicon (FZ and CZ), sapphire, silicon carbide; those materials coated with aluminum, silicon, diamond like carbon, and gold; and isotopically enriched polycrystalline diamond and amorphous carbon. The majority of these materials were distributed on five collector arrays. Three of the materials were housed in an electrostatic concentrator designed to increase the flux of low-mass ions. There was also a two-inch diameter bulk metallic glass collector and a gold foil, polished aluminum, and molybdenum coated platinum foil collector. An excellent review of the Genesis collector materials is offered in reference [1].

  15. Plant cutin genesis: unanswered questions.

    PubMed

    Domínguez, Eva; Heredia-Guerrero, José A; Heredia, Antonio

    2015-09-01

    The genesis of cutin, the main lipid polymer present in the biosphere, has remained elusive for many years. Recently, two main approaches have attempted to explain the process of cutin polymerization. One describes the existence of an acyltransferase cutin synthase enzyme that links activated monomers of cutin in the outer cell wall, while the other shows that plant cutin is the final result of an extracellular nonenzymatic self-assembly and polymerizing process of cutin monomers. In this opinion article, we explain both models and suggest that they could be pieces of a more complex biological scenario. We also highlight their different characteristics and current limitations, and suggest a potential synergism of both hypotheses.

  16. Genesis Noble Gas Measurements

    NASA Technical Reports Server (NTRS)

    Hohenberg, Charles M.

    2005-01-01

    The original thrust of our Genesis funding was to extend and refine the noble gas analytical capabilities of this laboratory to improve the precision and accuracy of noble gas measurements in order to optimize the scientific return from the Genesis Mission. This process involved both instrumental improvement (supplemented by a SRLIDAP instrument grant) and refinement of technique. The Genesis landing mishap shifted our emphasis to the irregular aluminum heat shield material from the flat collector wafers. This has required redesign of our laser extraction cells to accommodate the longer focal lengths required for laser extraction from non-flat surfaces. Extraction of noble gases from solid aluminum surfaces, rather than thin coatings on transparent substrates has required refinement of controlled-depth laser ablation techniques. Both of these bring new problems, both with potentially higher blanks form larger laser cells and the larger quantities of evaporated aluminum which can coat the sapphire entrance ports. This is mainly a problem for the heavy noble gases where larger extraction areas are required, necessitating the new aluminum vapor containment techniques described below. With the Genesis Mission came three new multiple multiplier noble gas mass spectrometers to this laboratory, one built solely by us (Supergnome-M), one built in collaboration with Nu-Instruments (Noblesse), and one built in collaboration with GVI (Helix). All of these have multiple multiplier detection sections with the Nu-Instruments using a pair of electrostatic quad lenses for isotope spacing and the other two using mechanically adjustable positions for the electron multipliers. The Supergnome-M and Noblesse are installed and running. The GVI instrument was delivered a year late (in March 2005) and is yet to be installed by GVI. As with all new instruments there were some initial development issues, some of which are still outstanding. The most serious of these are performance issues

  17. 3D numerical modeling of mantle flow, crustal dynamics and magma genesis associated with slab roll-back and tearing: The eastern Mediterranean case

    NASA Astrophysics Data System (ADS)

    Menant, Armel; Sternai, Pietro; Jolivet, Laurent; Guillou-Frottier, Laurent; Gerya, Taras

    2016-05-01

    Interactions between subduction dynamics and magma genesis have been intensely investigated, resulting in several conceptual models derived from geological, geochemical and geophysical data. To provide physico-chemical constraints on these conceptual models, self-consistent numerical simulations containing testable thermo-mechanical parameters are required, especially considering the three-dimensional (3D) natural complexity of subduction systems. Here, we use a 3D high-resolution petrological and thermo-mechanical numerical model to quantify the relative contribution of oceanic and continental subduction/collision, slab roll-back and tearing to magma genesis and transport processes. Our modeling results suggest that the space and time distribution and composition of magmas in the overriding plate is controlled by the 3D slab dynamics and related asthenospheric flow. Moreover, the decrease of the bulk lithospheric strength induced by mantle- and crust-derived magmas promotes the propagation of strike-slip and extensional fault zones through the overriding crust as response to slab roll-back and continental collision. Reduction of the lithosphere/asthenosphere rheological contrast by lithospheric weakening also favors the transmission of velocities from the flowing mantle to the crust. Similarities between our modeling results and the late Cenozoic tectonic and magmatic evolution across the eastern Mediterranean region suggest an efficient control of mantle flow on the magmatic activity in this region, which in turn promotes lithospheric deformation by mantle drag via melt-induced weakening effects.

  18. Early Jurassic subduction of the Paleo-Pacific Ocean in NE China: Petrologic and geochemical evidence from the Tumen mafic intrusive complex

    NASA Astrophysics Data System (ADS)

    Guo, Feng; Li, Hongxia; Fan, Weiming; Li, Jingyan; Zhao, Liang; Huang, Miwei; Xu, Wenliang

    2015-05-01

    Subduction of the Paleo-Pacific Oceanic Plate is widely considered to have caused extensive Mesozoic magmatism, lithospheric deformation and mineralization in East Asia. However, it is still unclear when this subduction began. Here we report an Early Jurassic (~ 187 Ma) mafic intrusive complex (including olivine norite, gabbro, and diorite) from the Tumen area in NE China. The olivine norite contains a mineral assemblage of olivine, pyroxene, Ca-plagioclase, and hornblende that crystallized in a water-saturated parental magma. The rocks in the complex show variable degrees of plagioclase and ferromagnesian mineral accumulation as reflected by positive Sr and Eu anomalies in primitive mantle-normalized incompatible element patterns. Mass-balance calculations indicate that the parental magma was calc-alkaline with arc-type trace element features (i.e., large ion incompatible and light rare earth element enrichment and Nb-Ta depletion). It also had Sr-Nd-Hf isotopic compositions (87Sr/86Sr(i) = 0.7042 to 0.7044, εNd(t) = + 2.5 to + 3.5 and εHf(t) = + 8.4 to + 10.5) similar to those of modern arc basalts. The parental magma was likely derived from 5 to 20% melting of a mantle wedge metasomatized by an addition of 3-4% hydrous sediment melt from the subducting Paleo-Pacific Oceanic slab. The Tumen mafic intrusive complex, together with other contemporaneous mafic intrusions, I-type granitoids, and felsic lavas, constitutes an Early Jurassic N-S-trending arc magmatic belt that was formed by westward subduction of the Paleo-Pacific Ocean.

  19. Petrological constraints on the recycling of mafic crystal mushes, magma ascent and intrusion of braided sills in the Torres del Paine mafic complex (Patagonia)

    NASA Astrophysics Data System (ADS)

    Leuthold, Julien; Müntener, Othmar; Baumgartner, Lukas; Putlitz, Benita

    2014-05-01

    Cumulate and crystal mush disruption and reactivation are difficult to recognise in coarse grained shallow plutonic rocks. Mafic minerals included in hornblende and zoned plagioclase provide snapshots of early crystallization and cumulate formation, but are difficult to interpret in terms of the dynamics of magma ascent and possible links between silicic and mafic rock emplacement. We will present the field relations, the microtextures and the mineral chemistry of the Miocene mafic sill complex of the Torres del Paine intrusive complex (Patagonia, Chile) and its sub-vertical feeder-zone. The mafic sill complex was built up by a succession of braided sills of shoshonitic and high-K calc-alkaline porphyritic hornblende-gabbro and fine grained monzodioritic sills. The mafic units were over-accreted over 41±11 ka, underplating the overlying granite. Local diapiric structures and felsic magma accumulation between sills indicate limited separation of intercumulus liquid from the mafic sills. Anhedral hornblende cores, with olivine + clinopyroxene ± plagioclase ± apatite inclusions, crystallized at temperatures >900°C and pressures of ~300 to ~500 MPa. The corresponding rims and monzodiorite matrix crystallized at <830°C, ~70 MPa. This abrupt compositional variation suggests stability and instability of hornblende during mafic roots recycling and subsequent decompression. The near lack of intercumulus crystals in the sub-vertical feeder zone layered gabbronorite and pyroxene-hornblende gabbronorite stocks testifies that melt is more efficiently extracted than in sills, resulting in a cumulate signature in the feeding system. The emplacement age of the sill complex topmost granitic unit is identical, within uncertainties, to the feeder zone mafic cumulates. Granitic liquids formed by AFC processes and were extracted at high temperature (T>950°C) from the middle crust reservoir to the emplacement level. We show that hornblende-plagioclase thermobarometry is a useful

  20. Geology and petrology of the plutonic complexes in the Wadi Fizh area: Multiple magmatic events and segment structure in the northern Oman ophiolite

    NASA Astrophysics Data System (ADS)

    Adachi, Yoshiko; Miyashita, Sumio

    2003-09-01

    Multiple magmatic events are recorded in the gabbroic unit in the Fizh area of the northern Oman ophiolite. Gabbroic blocks intruded by sheeted dike complex and upper gabbros of the main crustal sequence show the oldest event. Gabbronorite sills in the gabbroic blocks are nearly coeval with the host gabbro. Wehrlitic intrusions (wehrlite I) mark the third event of magmatism. These three magmatic events occurred at the retreating (dying) ridge axis because all these rocks are intruded by dolerite dike swarm, which is generally regarded as a precursor of advancing ridge axis. The next stage of magmatism is a main phase of oceanic crust generation in this area. Wehrlite II and then gabbronorite dikes intrude the still hot main gabbro unit. All of these above rocks have similar signatures with respect to clinopyroxene compositions and covariations between plagioclase and mafic minerals, though slight differences are present in the compositional ranges and clinopyroxene compositions of each unit. After considerable cooling of the main gabbro unit, primitive basalt dikes intrude the main gabbro unit, which may correspond to the Lasail unit. Finally, the Fizh-South complex intrudes into considerably cooled crustal sequence, being below the brittle-plastic transition temperatures. The Fizh-South complex, which was regarded as a common wehrlitic intrusion, is significantly different from all of the above mentioned rocks, with respect to the covariation between plagioclase and associating mafic minerals, crystallization order, and clinopyroxene compositions. The clinopyroxenes are characterized by extremely low Ti and Na contents, comparable with those of the V2 unit (Alley volcanics), suggesting that the Fizh-South complex correlates with the plutonic facies of the V2 unit during arc stage. Layered gabbros in the Wadi Zabin area, about 10 km north of the Fizh area, may be a northern extension of the gabbro blocks of the Fizh area, because they are intruded by numerous

  1. Theoretical petrology. [of igneous and metamorphic rocks

    NASA Technical Reports Server (NTRS)

    Stolper, E.

    1979-01-01

    In the present paper, some areas of growing interest in the American efforts in petrology during the 1975-1978 quadrennium are reviewed. In igneous petrology, studies of structures and thermodynamic properties of silicate melts and of kinetics of igneous processes are in a period of rapid growth. Plate tectonic concepts have had (and will no doubt continue to have) an important influence by focusing interest on specific problems and by providing a framework for the understanding of petrogenesis. An understanding of mantle processes and evolution through the integration of petrological, geophysical, and geochemical constraints has been developed over the past 20 years, and will undoubtedly provide direction for future petrological studies.

  2. Field, petrologic and detrital zircon study of the Kings sequence and Calaveras complex, Southern Lake Kaweah Roof Pendant, Tulare County, California

    NASA Astrophysics Data System (ADS)

    Buchen, Christopher T.

    U-Pb dating of detrital zircon grains separated from elastic sedimentary rocks is combined with field, petrographic and geochemical data to reconstruct the geologic history of Mesozoic rocks exposed at the southern end of the Lake Kaweah metamorphic pendant, western Sierra Nevada. Identification of rocks exposed at Limekiln Hill, Kern County, CA, as belonging to the Calaveras complex and Kings sequence was confirmed. Detrital zircon populations from two Calaveras complex samples provide Permo-Triassic maximum depositional ages (MDA) and reveal a Laurentian provenance indicating that continental accretion of the northwest-trending Kings-Kaweah ophiolite belt was in process prior to the Jurassic Period. Rock types including radiolarian metachert, metachert-argillite, and calc-silicate rocks with marble lenses are interpreted as formed in a hemipelagic environment of siliceous radiolarian deposition, punctuated by extended episodes of lime-mud gravity flows mixing with siliceous ooze forming cafe-silicate protoliths and limestone olistoliths forming marble lenses. Two samples of the overlying Kings sequence turbidites yield detrital zircons with an MDA of 181.4 +/-3.0 Ma and an interpreted provenance similar to other Jurassic metasediments found in the Yokohl Valley, Sequoia and Boyden Cave roof pendants. Age peaks indicative of Jurassic erg heritage are also present. In contrast, detrital zircon samples from the Sequoia and Slate Mountain roof pendants bear age-probability distributions interpreted as characteristic of the Snow Lake block, a tectonic sliver offset from the Paleozoic miogeocline.

  3. Petrology and geochronology of Xuejiashiliang igneous complex and their genetic link to the lithospheric thinning during the Yanshanian orogenesis in eastern China

    NASA Astrophysics Data System (ADS)

    Su, Shangguo; Niu, Yaoling; Deng, Jinfu; Liu, Cui; Zhao, Guochun; Zhao, Xingguo

    2007-06-01

    The Xuejiashiliang igneous complex, ˜ 150 km north of the City of Beijing, is an important member of the Mesozoic Yanshanian orogen in eastern China. This complex consists of gabbro, monzogabbro, monzonite, syenite and granite. In situ zircon U/Pb dating shows that the Xuejiashiliang complex was emplaced at ˜ 128.8-123.7 Ma (i.e., K 11). Field and petrographic observations together with bulk-rock major element, trace element and Sr-Nd-Pb isotopic data suggest that the gabbro represent remnants of a mafic intrusion formed from cooling of a mantle derived melt that underplated beneath or intruded into the lower crust. The monzogabbro may be the product of deep crustal assimilation of this mantle derived melt. The syenite may have precipitated from a melt produced by deep crustal melting caused by the mantle derived melt. The monzonite may have formed from mixing between melts parental to the syenite and monzogabbro. That is, all these diverse lithologies may have resulted from varying degrees of mantle melt induced crustal melting, melt assimilation, differentiation and mixing. The granite is best interpreted as resulting from upper crustal melting and advanced degrees of differentiation. The remarkably similar Nb-Sr-Pb isotopes of all these lithologies (except for 87Sr/ 86Sr of the granite) with an "EM1-like" signature point to a common source they share. This common source could be ancient lithospheric mantle, but we consider the Archean lower crust to be the more likely candidate. The high 87Sr/ 86Sr (0.8955) of the granite resulted from radiogenic ingrowth of 87Sr due to the elevated Rb/Sr ratio (˜ 22.4). The high [La/Yb] CN and Sr/Y ratios of all these lithologies (except the granite) are consistent with magma genes at depths where garnet is a stable phase. This is consistent with the condition of syenite genes that requires pressures equivalent to depths in excess of 50 km. All these constrain that the complex may have formed at the base of the thickened

  4. Petrology and tectonic significance of gabbros, tonalites, shoshonites, and anorthosites in a late Paleozoic arc-root complex in the Wrangellia Terrane, southern Alaska

    SciTech Connect

    Beard, J.S. ); Barker, F. )

    1989-11-01

    Plutonic rocks intrusive into the late Paleozoic Tetelna Formation of southern Alaska are the underpinnings of the late Paleozoic Skolai arc of the Wrangellia Terrane. There are four groups of intrusive rocks within the Skolai arc: (1) Gabbro-diorite plutons that contain gabbroic to anorthositic cumulates along with a differentiated series of gabbros and diorites of basaltic to andesitic composition; (2) Silicic intrusions including tonalite, granodiorite, and granite; (3) Monzonitic to syenitic plutonic rocks of the Ahtell complex and related dikes and sills; (4) Fault-bounded bytownite anorthosite of uncertain age and association. These anorthosites may be related to post-Skolai, Nikolai Greenstone magmatism. The silicic rocks yield discordant U-Pb zircon ages of 290-320 Ma (early to late Pennsylvanian). The monzonitic rocks of the Ahtell complex have shoshonitic chemistry. Similar shoshonitic rocks are widespread in both the Wrangellia terrane and the neighboring Alexander terrane and intrude the contact between the two. In modern oceanic arcs, shoshonitic rocks are typically associated with tectonic instability occurring during the initial stages of subduction or just prior to or during termination or flip of an established subduction zone. The nature of any tectonic instability which may have led to the cessation of subduction in the Skolai arc is unclear. Possibilities include collision of the arc with a ridge, an oceanic plateau, another arc, or a continental fragment. One possibility is that the shoshonitic magmatism marks the late Paleozoic amalgamation of Wrangellia and the Alexander terrane. The scarcity of arc rocks predating the shoshonites in the Alexander terrane supports this possibility, but structural corroboration is lacking.

  5. Geological and petrological aspects of Ni-Cu-PGE mineralization in the early Paleoproterozoic Monchegorsk layered mafic-ultramafic complex, Kola Peninsula

    NASA Astrophysics Data System (ADS)

    Sharkov, E. V.; Chistyakov, A. V.

    2014-05-01

    The Early Paleoproterozoic Monchegorsk Complex comprises two independent large layered mafic-ultramafic intrusions: the Monchegorsk pluton and the Main Range massif formed about 2.50 and 2.46 Ga ago, respectively. They are composed of similar cumulates, though they differ somewhat in the isotopic parameters of rocks, cumulate stratigraphy and derived from siliceous high-Mg series melts that arose in the same large long-living volcanic center. The economic syngenetic Ni-Cu-PGE sulfide mineralization related to the earlier Monchegorsk pluton is represented by two types of ores. The first type, pertaining to fractionation of the primary melt, is opposite to the reef formed due to injection of a special ore-bearing melt into the solidifying intrusive chamber. The primary magmatic mineralization is largely composed of Ni-Fe-Cu sulfides and Pd-Pt sulfides, bismuthides, and tellurides. Only small PGE and probably chromite occurrences are related to the Main Range massif. In the Mid-Paleoproterozoic (2.0-1.9 Ga), the complex was transformed into a collage of tectonic blocks confined to the regional fault zone. The Monchegorsk pluton was retained better, and only rocks of its southern framework were involved into tectonic and metamorphic reworking with the formation of economic metamorphic low-sulfide PGE mineralization with widespread Pd and Pt telluro-bismuthides, arsenides, stannides, antimonides, and selenides. The ore formation was accompanied by PGE redistribution and segregation of lenticular orebodies with diffuse contours. Thus, the Monchegorsk ore cluster is characterized by juxtaposition of unaltered primary magmatic deposits and those formed as a result of their metamorphism and distinguished from the former by structure and composition. The comparative study of these deposits opens up new possibilities for comprehending ore-forming processes in the same situations.

  6. Modal Petrology and Geostatistics of the Blue Hills Igneous Complex, Boston, Massachusetts, by Rietveld X-ray Diffraction: Multi-scalar Investigation of Volcanic and Intrusive Relationships

    NASA Astrophysics Data System (ADS)

    Besancon, J. R.; Spence, T. M.

    2004-12-01

    The Blue Hills Igneous Complex of eastern Massachusetts consists of mildly peralkaline volcanic and intrusive units including the Quincy Granite, the Blue Hills Porphyry, and a set of mainly pyroclastic rhyolite flow units traditionally called the Aporhyolite. Similar whole-rock chemistry has led most workers to assume that they are related rocks, despite some unclear field relationships. Kaktins (1976) divided the volcanic rocks into six units, but buried contacts do not permit confidence in either their number or stratigraphic position. To test a new method of modal analysis of these rocks, thirty-five samples were crushed, ground to approximately 5 micrometers, spray-dried to produce randomly oriented powder, and analyzed by x-ray diffraction. A constant eleven-phase Rietveld starting model was applied to the x-ray spectra, and then refined to produce a modal database of phase proportions in each sample. Geostatistical analysis with GIS software delineates a number of trends, with statistical measures of uncertainty. Aegirine in volcanics decreases in abundance with distance south from the E-W contact of volcanic rocks and granite. Riebeckite is found in the granite (both as veins and as apparently magmatic crystals) and the porphyry, but is less abundant or absent among the volcanic rocks. Where both amphibole and pyroxene are present, they are negatively correlated. The goal is to develop an additional tool for correlation of volcanic rocks, one based on mineral proportions in both aphanitic and phaneritic rocks.

  7. A Digital Approach to Learning Petrology

    NASA Astrophysics Data System (ADS)

    Reid, M. R.

    2011-12-01

    In the undergraduate igneous and metamorphic petrology course at Northern Arizona University, we are employing petrographic microscopes equipped with relatively inexpensive ( $200) digital cameras that are linked to pen-tablet computers. The camera-tablet systems can assist student learning in a variety of ways. Images provided by the tablet computers can be used for helping students filter the visually complex specimens they examine. Instructors and students can simultaneously view the same petrographic features captured by the cameras and exchange information about them by pointing to salient features using the tablet pen. These images can become part of a virtual mineral/rock/texture portfolio tailored to individual student's needs. Captured digital illustrations can be annotated with digital ink or computer graphics tools; this activity emulates essential features of more traditional line drawings (visualizing an appropriate feature and selecting a representative image of it, internalizing the feature through studying and annotating it) while minimizing the frustration that many students feel about drawing. In these ways, we aim to help a student progress more efficiently from novice to expert. A number of our petrology laboratory exercises involve use of the camera-tablet systems for collaborative learning. Observational responsibilities are distributed among individual members of teams in order to increase interdependence and accountability, and to encourage efficiency. Annotated digital images are used to share students' findings and arrive at an understanding of an entire rock suite. This interdependence increases the individual's sense of responsibility for their work, and reporting out encourages students to practice use of technical vocabulary and to defend their observations. Pre- and post-course student interest in the camera-tablet systems has been assessed. In a post-course survey, the majority of students reported that, if available, they would use

  8. Petrology, geochemistry, and metamorphic evolution of meta-sedimentary rocks in the Diancang Shan-Ailao Shan metamorphic complex, Southeastern Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Wang, Fang; Liu, Fulai; Liu, Pinghua; Shi, Jianrong; Cai, Jia

    2016-07-01

    Meta-sedimentary rocks are widely distributed within the Diancang Shan-Ailao Shan metamorphic complex in the Southeastern Tibetan Plateau. Detailed geochemical analyses show that all of them have similar geochemical features. They are enriched in light rare-earth elements (LREEs) and depleted in heavy rare-earth elements (HREEs), with moderately negative Eu anomalies (Eu/Eu∗ = 0.55-0.75). Major and trace element compositions for the meta-sedimentary rocks suggest that the protoliths were probably claystone, siltstone, and greywacke and deposited in an active continental margin. Garnet porphyroblasts in meta-sedimentary rocks have distinct compositional zonation from core to rim. The zonation of garnet in St-Ky-Grt-Bt-Ms schist indicates an increasing P-T trend during garnet growth. In contrast, garnets from (Sil)-Grt-Bt paragneiss show diffusion zoning, implying a decreasing P-T trend. Based on mineral transformations and P-T estimates using conventional geothermobarometers and pseudosection calculations, four metamorphic stages have been determined, including an early prograde metamorphic stage (M1), a peak amphibolite-granulite facies metamorphic stage (M2), a near-isothermal decompression stage (M3), and a late amphibolites-facies retrograde stage (M4). The relic assemblage of Ms + St ± Ky ± Bt ± Kfs + Qz preserved as inclusions in garnet porphyroblasts of the meta-sedimentary rocks belongs to prograde (M1) stage and records P-T conditions of 560-590 °C and 5.5-6.3 kb. Matrix mineral assemblages of Grt + Bt + Ky/Sil + Pl + Qz and Grt + Bt ± Sil + Pl ± Kfs + Qz formed at peak (M2) stage yield P-T conditions of 720-760 °C and 8.0-9.3 kb. M3 is characterized by decompression reactions, dehydration melting of assemblages that include hydrous minerals (e.g., biotite), and partial melting of felsic minerals. The retrograde assemblages is Grt + Bt + Sil + Pl + Qz formed at 650-760 °C and 5.0-7.3 kb. At the amphibolites-facies retrograde (M4) stage, fine

  9. Petrology of melilite-bearing rocks from the Montefiascone Volcanic Complex (Roman Magmatic Province): new insights into the ultrapotassic volcanism of Central Italy

    NASA Astrophysics Data System (ADS)

    Di Battistini, G.; Montanini, A.; Vernia, L.; Venturelli, G.; Tonarini, S.

    2001-10-01

    The products of Montefiascone Volcanic Complex (MVC) encompass one of the most distinct association of potassic to ultrapotassic rocks of the Roman Magmatic Province (RMP), ranging in composition from trachybasalts to tephritic leucitites. New discovery of leucite melilitites, occurring as small lava flows, and of kalsilite-melilite pyroclastic ejecta, further expand the compositional range of the MVC products towards the extreme ultrapotassic compositions of the nearby Umbria-Latium Intra Apenninic Volcanism (IAV). Both lavas and ejecta are characterized by strong LILE and Th enrichments coupled with HFSE depletion, very radiogenic 87Sr/ 86Sr (0.7104-0.7106) and unradiogenic 143Nd/ 144Nd (0.51209-0.51213). Mineral and whole-rock chemistry indicate that the leucite melilites are transitional between ultrapotassic larnite-free, Roman-type magmas and kamafugites, whereas the ejecta (kalsilite melilitolites and clinopyroxene-kalsilite melilitolites) can be considered as intrusive kamafugites. Significant interactions with country rocks (mainly limestones and marls) have been excluded on the basis of trace elements and Sr-Nd isotopes, showing that low SiO 2, high (Ca+Na+K)/Al ratios and relatively high CO 2 contents (leading to crystallization of interstitial carbonates in both lavas and ejecta), are primary features of the melts which yielded the melilites and melilite-bearing ejecta. Petrogenesis of the whole range of MVC products is related to melting in the deepest part of a thinned lithosphere characterized by carbonate-bearing phlogopite-clinopyroxene veins with highly radiogenic 87Sr/ 86Sr and unradiogenic 143Nd/ 144Nd; progressive dilution of a vein-derived, K-rich (kamafugitic) end-member by a basaltic melt originated from a relatively depleted mantle would be able to explain the entire compositional range of MVC magmas. The common geochemical and isotopic signatures of MVC and IAV volcanics suggest that the same petrogenetic processes were simultaneously

  10. Petrology, geochemistry, and mineralogy of pyroxene and pegmatitic carbonatite and the associated fluorspar deposit at Okorusu alkaline igneous carbonatite complex, Namibia

    NASA Astrophysics Data System (ADS)

    Shivdasan, Purnima Ashok

    Field observations, petrography, electron microprobe analysis (EPMA), geothermometry, and geochemical analyses (ICP-MS and XRF) of the fluorspar deposit associated with the Late Cretaceous alkaline igneous-carbonatite complex at Okorusu (Namibia) have identified two previously unrecognized types of carbonatites, namely pyroxene and pegmatitic carbonatites. These carbonatites exhibit interesting textural characteristics, with the pyroxene carbonatite exhibiting occasional bands of diopside alternating with coarse-grained calcite-rich bands, and pegmatitic carbonatite having the same mineralogy but much coarser texture. Both types of carbonatites are closely spatially associated. Ulvospinel ex-solution lamellae were recognized in magnetite crystals within the pyroxene and pegmatitic carbonatite. Stable isotope determinations for calcite crystals separated from pegmatitic carbonatites, pyroxene carbonatites, and marbles indicate that the carbonatites are primary in origin. Cathodoluminescence microscopy (CL) and emission spectrography of the carbonatites indicated that the carbonate mineral is almost entirely calcite rather than dolomite, and there are at least two generations of calcite. CL study of fenites, which are metasomatised Precambrian metasedimentary rocks, intruded by carbonatites reveal that fenitization is mostly incipient, marked by the introduction of Fe3+ activated feldspars. Geothermometric determination from EPMA of apatite and biotite in pyroxene carbonatite provided a range of 537--409°C except in one sample which clearly indicated later hydrothermal alteration. The temperature range is similar to a previous titaniferous magnetite-ilmenite temperature determination and is interpreted to represent magmatic crystallization. Trace element patterns of carbonatites are largely consistent with the results of previous studies, although phosphorus values are anomalously high because of apatite. As one of only two producing carbonatite-related fluorspar

  11. Petrology and mineralogy of the La Peña igneous complex, Mendoza, Argentina: An alkaline occurrence in the Miocene magmatism of the Southern Central Andes

    NASA Astrophysics Data System (ADS)

    Pagano, Diego Sebastián; Galliski, Miguel Ángel; Márquez-Zavalía, María Florencia; Colombo, Fernando

    2016-04-01

    The La Peña alkaline igneous complex (LPC) is located in the Precordillera (32°41‧34″ S - 68°59‧48″ W) of Mendoza province, Argentina, above the southern boundary of the present-day flat-slab segment. It is a 19 km2 and 5 km diameter subcircular massif emplaced during the Miocene (19 Ma) in the Silurian-Devonian Villavicencio Fm. The LPC is composed of several plutonic and subvolcanic intrusions represented by: a cumulate of clinopyroxenite intruded by mafic dikes and pegmatitic gabbroic dikes, isolated bodies of malignite, a central intrusive syenite that develops a wide magmatic breccia in the contact with clinopyroxenite, syenitic and trachytic porphyries, a system of radial and ring dikes of different compositions (trachyte, syenite, phonolite, alkaline lamprophyre, tephrite), and late mafic breccias. The main minerals that form the LPC, ordered according to their abundance, are: pyroxene (diopside, hedenbergite), calcium amphibole (pargasite, ferro-pargasite, potassic-ferro-pargasite, potassic-hastingsite, magnesio-hastingsite, hastingsite, potassic-ferro-ferri-sadanagaite), trioctahedral micas (annite-phlogopite series), plagioclase (bytownite to oligoclase), K-feldspar (sanidine and orthoclase), nepheline, sodalite, apatite group minerals (fluorapatite, hydroxylapatite), andradite, titanite, magnetite, spinel, ilmenite, and several Cu-Fe sulfides. Late hydrothermal minerals are represented by zeolites (scolecite, thomsonite-Ca), epidote, calcite and chlorite. The trace element patterns, coupled with published data on Sr-Nd-Pb isotopes, suggest that the primary magma of the LPC was generated in an initially depleted but later enriched lithospheric mantle formed mainly by a metasomatized spinel lherzolite, and that this magmatism has a subduction-related signature. The trace elements pattern of these alkaline rocks is similar to other Miocene calc-alkaline occurrences from the magmatic arc of the Southern Central Andes. Mineral and whole

  12. Petrology of the igneous rocks

    NASA Technical Reports Server (NTRS)

    Mccallum, I. S.

    1987-01-01

    Papers published during the 1983-1986 period on the petrology and geochemistry of igneous rocks are discussed, with emphasis on tectonic environment. Consideration is given to oceanic rocks, subdivided into divergent margin suites (mid-ocean ridge basalts, ridge-related seamounts, and back-arc basin basalts) and intraplate suites (oceanic island basalts and nonridge seamounts), and to igneous rocks formed at convergent margins (island arc and continental arc suites), subdivided into volcanic associations and plutonic associations. Other rock groups discussed include continental flood basalts, layered mafic intrusions, continental alkalic associations, komatiites, ophiolites, ash-flow tuffs, anorthosites, and mantle xenoliths.

  13. Lunar breccias, petrology, and earth planetary structure

    NASA Technical Reports Server (NTRS)

    Ridley, W. I.

    1978-01-01

    Topics covered include: (1) petrologic studies of poikiloblastic textured rocks; (2) petrology of aluminous mare basalts in breccia 14063; (3) petrology of Apollo 15 breccia 15459; (4) high-alumina mare basalts; (5) some petrological aspects of imbrium stratigraphy; (6) petrology of lunar rocks and implication to lunar evolution; (7) the crystallization trends of spinels in Tertiary basalts from Rhum and Muck and their petrogenetic significance; (8) the geology and evolution of the Cayman Trench; (9) The petrochemistry of igneous rocks from the Cayman Trench and the Captains Bay Pluton, Unalaska Island and their relation to tectonic processes at plate margins; and (10) the oxide and silicate mineral chemistry of a Kimberlite from the Premier Mine with implications for the evolution of kimberlitic magma.

  14. Neoarchean-Early Paleoproterozoic and Early Neoproterozoic arc magmatism in the Lützow-Holm Complex, East Antarctica: Insights from petrology, geochemistry, zircon U-Pb geochronology and Lu-Hf isotopes

    NASA Astrophysics Data System (ADS)

    Tsunogae, Toshiaki; Yang, Qiong-Yan; Santosh, M.

    2016-10-01

    The Lützow-Holm Complex (LHC) of East Antarctica forms part of the Neoproterozoic-Cambrian high-grade metamorphic segment of the East African-Antarctic Orogen. Here we present new petrological, geochemical, and zircon U-Pb and Lu-Hf isotopic data for meta-igneous rocks including charnockite, felsic gneiss, metagabbro, and mafic granulite from the LHC and evaluate the Neoarchean to Early Paleoproterozoic (ca. 2.5 Ga) and Early Neoproterozoic (ca. 1.0 Ga) arc magmatic events. The trace element geochemical signatures reveal a volcanic arc affinity for the charnockites from Sudare Rocks and Vesleknausen and felsic gneiss from Rundvågshetta, suggesting that the protoliths of these rocks were derived from felsic arc magmas. In contrast, metagabbros from Skallevikshalsen and Austhovde, occurring as boudins in metasediments, show non-arc signatures (within-plate basalt or mid-oceanic ridge basalt). The upper intercept ages of magmatic zircons in charnockite plotted on concordia diagrams yielded 2508 ± 14 Ma (Sudare Rocks) and 2490 ± 18 Ma (Vesleknausen), clearly suggesting a Neoarchean to Early Paleoproterozoic arc magmatic event. A subsequent thermal event during Early Neoproterozoic traced by 206Pb/238U age of oscillatory-zoned core of zircon in mafic granulite from Langhovde (973 ± 10 Ma) is consistent with a similar Early Neoproterozoic magmatic event reported from the LHC, suggesting a second stage of arc magmatism. The timing of peak metamorphism has been inferred from 206Pb/238U mean ages of structureless zircons in metagabbros from Skallevikshalsen and Austhovde, mafic granulite from Langhovde, and felsic gneiss from Rundvågshetta in the range of 551 ± 5.4 to 584 ± 5.0 Ma. Zircon Lu-Hf data of Neoarchean charnockites from Sudare Rocks and Vesleknausen indicate that the protolith magma was sourced from Paleo- to Neoarchean juvenile components mixed with reworked ancient crustal materials. Protolith magmatic rock of the felsic gneiss from Rundvågshetta might

  15. The Genesis of SESAPS

    NASA Astrophysics Data System (ADS)

    Mickens, Ronald

    2008-04-01

    On March 23, 1935, a meeting of ``Southern Physicist" was held at the Candler Hotel in Decatur, Georgia. In addition to a scientific program the next day, consisting of the presentation of twenty-five papers (held in the Emory University's chemistry building), an address was given by Professor A. H. Compton on that Friday night during a banquet sponsored by the Georgia Academy of Science. However, the main goal of this meeting was to work out the details of a new organization, which was called the ``Southern Association of Physicists." My talk provides background on the genesis of this gathering and gives a brief summary of the new organization's subsequent activities, including its ``absorption" by the American Physical Society as its Southeastern Section, i.e., SESAPS. In particular, I discuss its management structure; its three awards for teaching, research, and leadership; and the planning process for its annual meeting. My general conclusion is that SESAPS has been very successful in promoting ``physics" in the southeastern states.

  16. The Flare Genesis Experiment

    NASA Technical Reports Server (NTRS)

    Rust, D. M.

    2002-01-01

    Using the Flare Genesis Experiment (FGE), a balloon-borne observatory with an 80-cm solar telescope we observed the active region NOAA 8844 on January 25, 2000 for several hours. FGE was equipped with a vector polarimeter and a tunable Fabry-Perot narrow-band filter. It recorded time series of filtergrams, vector magnetograms, and Dopplergrams at the Ca(I) 6122.2 angstrom line, and H-alpha filtergrams with a cadence between 2.5 and 7.5 minutes. At the time of the observations, NOAA 8844 was located at approximately 5 N 30 W. The region was rapidly growing during the observations; new magnetic flux was constantly emerging in three supergranules near its center. We describe in detail how the FGE data were analyzed and report on the structure and behavior of peculiar moving dipolar features (MDFs) observed in the active region. In longitudinal magnetograms, the MDFs appeared to be small dipoles in the emerging fields. The east-west orientation of their polarities was opposite that of the sunspots. The dipoles were oriented parallel to their direction of motion, which was in most cases towards the sunspots. Previously, dipolar moving magnetic features have only been observed flowing out from sunspots. Vector magnetograms show that the magnetic field of each MDF negative part was less inclined to the local horizontal than the ones of the positive part. We identify the MDFs as undulations, or stitches, where the emerging flux ropes are still tied to the photosphere. We present a U-loop model that can account for their unusual structure and behavior, and it shows how emerging flux can shed its entrained mass.

  17. Sedimentary petrology. 2nd edition

    SciTech Connect

    Blatt, H.

    1992-01-01

    The second edition of Sedimentary Petrology is extensively revised and updated; much effort has been expended to strengthen the weaknesses of the earlier edition, and much of this effort has been successful. It consists of sixteen chapters. Following two introductory chapters (occurrence of sedimentary rocks; weathering and soils), eleven chapters cover the various sedimentary rock types. Coverage is allocated in proportion to their relative abundance and relative ease of study -- three chapters on conglomerates and sandstones (textures and structures, composition, and diagenesis); one on mud rocks; three on carbonates (limestone textures, structures, and environments; limestone mineralogy and diagenesis; and dolostones); and one each on evaporites, cherts, iron-rich rocks, and phosphorites. A novel and useful chapter on paleogeothermometry rounds out the discussion of rocks, followed by chapters on The Development of a Research Project'' and common laboratory methods.

  18. Petrological studies on lunar rock samples

    NASA Technical Reports Server (NTRS)

    Kushiro, I.

    1974-01-01

    Petrological studies were made on Apollo 14, 15, 16, and 17 lunar samples. High-pressure melting experiments were conducted, along with electron microprobe analyses. The composition of the samples is reported.

  19. [The influence of environment complexity and individual's reactivity on the genesis of schizophrenic delusions and on the differences in their content].

    PubMed

    Czerwińska, M

    1994-01-01

    The present paper tries to answer two questions: 1. Is there a connection between the occurrence of delusions in paranoid schizophrenics and the lack of them in healthy people, and the complexity of their environment and the level of their reactivity? 2. Is there a connection between the differentiation of the delusion's content, and the level of reactivity of the examined schizophrenics? Examined were 26 paranoid schizophrenics (13 with delusions of grandeur and 13 with delusions of persecution) and 26 healthy people.

  20. Carbon petrology in cometary dust

    NASA Technical Reports Server (NTRS)

    Rietmeijer, Frans J. M.

    1992-01-01

    Chondritic porous (CP) interplanetary dust particles (IDP's) are collected in the Earth's stratosphere. There exists an extensive database on major and minor element chemistry, stable isotopes, noble gas abundances and mineralogy of many CP IDP's, as well as infrared and Raman spectroscopic properties. For details on the mineralogy, chemistry and physical properties of IDP's, I refer to the reviews by Mackinnon and Rietmeijer (1987), Bradley et al. (1988) and Sandford (1987). Texture, mineralogy (Mackinnon and Rietmeijer, 1987) and chemistry (Schramm et al., 1989; Flynn and Sutton, 1991) support the notion that CP IDP's are a unique group of ultrafine-grained extraterrestiral materials that are distinct from any known meteorite class. Their fluffy, or porous, morphology suggests that CP IDP's probably endured minimal alteration by protoplanetary processes since their formation. It is generally accepted that CP IDP's are solid debris from short-period comets. The evidence is mostly circumstantial but this notion gained significant support based on the comet Halley dust data (Brownlee, 1990). In this paper, I will accept that CP IDP's are indeed cometary dust. The C/Si ratio in CP IDP's is 3.3 times higher than in CI carbonaceous chondrites (Schramm et al. 1989). The intraparticle carbon distribution is heteorogeneous (Rietmeijer and McKay, 1986). Carbon occurs both in oxidized and reduced forms. Analytical electron microscope (AEM) and Raman spectroscopic analyses have shown the presence of several carbon forms in CP IDP's but the data are scattered in the literature. Carbons in cometary CP IDP's are among the most pristine Solar System carbons available for laboratory study. Similar to a recently developed petrological model for the diversity of layer silicates in CP IDP's (Zolensky, 1991) that is useful to constrain in situ aqueous alteration in comets (Rietmeijer and Mackinnon, 1987a), I here present the first effort to develop a petrological concept of carbons

  1. Carbon petrology in cometary dust

    NASA Astrophysics Data System (ADS)

    Rietmeijer, Frans J. M.

    1992-12-01

    Chondritic porous (CP) interplanetary dust particles (IDP's) are collected in the Earth's stratosphere. There exists an extensive database on major and minor element chemistry, stable isotopes, noble gas abundances and mineralogy of many CP IDP's, as well as infrared and Raman spectroscopic properties. For details on the mineralogy, chemistry and physical properties of IDP's, I refer to the reviews by Mackinnon and Rietmeijer (1987), Bradley et al. (1988) and Sandford (1987). Texture, mineralogy (Mackinnon and Rietmeijer, 1987) and chemistry (Schramm et al., 1989; Flynn and Sutton, 1991) support the notion that CP IDP's are a unique group of ultrafine-grained extraterrestiral materials that are distinct from any known meteorite class. Their fluffy, or porous, morphology suggests that CP IDP's probably endured minimal alteration by protoplanetary processes since their formation. It is generally accepted that CP IDP's are solid debris from short-period comets. The evidence is mostly circumstantial but this notion gained significant support based on the comet Halley dust data (Brownlee, 1990). In this paper, I will accept that CP IDP's are indeed cometary dust. The C/Si ratio in CP IDP's is 3.3 times higher than in CI carbonaceous chondrites (Schramm et al. 1989). The intraparticle carbon distribution is heteorogeneous (Rietmeijer and McKay, 1986). Carbon occurs both in oxidized and reduced forms. Analytical electron microscope (AEM) and Raman spectroscopic analyses have shown the presence of several carbon forms in CP IDP's but the data are scattered in the literature. Carbons in cometary CP IDP's are among the most pristine Solar System carbons available for laboratory study. Similar to a recently developed petrological model for the diversity of layer silicates in CP IDP's (Zolensky, 1991) that is useful to constrain in situ aqueous alteration in comets (Rietmeijer and Mackinnon, 1987a), I here present the first effort to develop a petrological concept of carbons

  2. Regional seismic reflection line, southern Illinois Basin, provides new data on Cambrian rift geometry, Hicks Dome genesis, and the Fluorspar Area Fault Complex

    SciTech Connect

    Potter, C.J.; Goldhaber, M.B.; Taylor, C.D. ); Heigold, P.C. )

    1992-01-01

    Detailed studies of the subsurface structure of the Cambrian Reelfoot rift (RFR) in the Midwestern US provide important insights into continental rifting processes and into the structural fabric of a zone of modern intracratonic seismicity (New Madrid zone). High-quality oil industry seismic reflection data show that in the area of transition between the RFR and the Rough Creek Graben (RCG) the geometry of the Cambrian rift system is that of a half-graben that thickens to the southeast. This contrasts with the northward-thickening half-graben observed to the east in the RCG and with the more symmetric graben to the south in the RFR. An 82.8-km segment of a northwest-southeast seismic reflection profile in southeastern Illinois and western Kentucky shows that near Hicks Dome, Illinois, Middle and Lower Cambrian syn-rift sedimentary rocks occupy about 0.35 s (two-way travel time) on the seismic reflection section (corresponding to a thickness of about 970 m). This stratigraphic interval occupies about 0.45 s (1,250 m) near the Ohio river and is thickest against the Tabb Fault System (TFS) in Kentucky, where it occupies 0.7 s (1,940 m). The seismic data show that in this part of the Cambrian rift the master fault was part of the TFS and that normal displacement on the TFS continued through middle Paleozoic time. The seismic data also provide new information on the late Paleozoic development of Hicks-Dome and the surrounding Fluorspar Area Fault Complex (FAFC) in southeastern Illinois and western Kentucky. A series of grabens and horsts in the FAFC document a late Paleozoic reactivation of the RFR. Comparison of the reflection data with surface mineralization patterns shows that in most cases mineralized graben-bounding faults clearly cut basement or are splays from faults that cut basement.

  3. Multiple sulfur isotope and mineralogical constraints on the genesis of Ni-Cu-PGE magmatic sulfide mineralization of the Monchegorsk Igneous Complex, Kola Peninsula, Russia

    NASA Astrophysics Data System (ADS)

    Bekker, A.; Grokhovskaya, T. L.; Hiebert, R.; Sharkov, E. V.; Bui, T. H.; Stadnek, K. R.; Chashchin, V. V.; Wing, B. A.

    2016-12-01

    We present the results of a pilot investigation of multiple sulfur isotopes for the Ni-Cu-PGE sulfide mineralization of the ˜2.5 Ga Monchegorsk Igneous Complex (MIC). Base Metal Sulfide (BMS) compositions, Platinum Group Element (PGE) distributions, and Platinum Group Mineral (PGM) assemblages were also studied for different types of Ni-Cu-PGE mineralization. The uniformly low S content of the country rocks for the MIC as well as variable Sm-Nd isotope systematics and low-sulfide, PGE-rich mineralization of the MIC suggest that S saturation was reached via assimilation of silicates rather than assimilation of sulfur-rich lithologies. R-factor modeling suggests that the mixing ratio for silicate-to-sulfide melt was very high, well above 15,000 for the majority of our mineralized samples, as might be expected for the low-sulfide, PGE-rich mineralization of the MIC. Small, negative Δ33S values (from -0.23 to -0.04 ‰) for sulfides in strongly metamorphosed MIC-host rocks indicate that their sulfur underwent mass-independent sulfur isotope fractionation (MIF) in the oxygen-poor Archean atmosphere before it was incorporated into the protoliths of the host paragneisses and homogenized during metamorphism. Ore minerals from the MIC have similar Δ33S values (from -0.21 to -0.06 ‰) consistent with country rock assimilation contributing to sulfide saturation, but, also importantly, our dataset suggests that Δ33S values decrease from the center to the margin of the MIC as well as from early to late magmatic phases, potentially indicating that both local assimilation of host rocks and S homogenization in the central part of the large intrusion took place.

  4. The geochemistry of primitive volcanic rocks of the Ankaratra volcanic complex, and source enrichment processes in the genesis of the Cenozoic magmatism in Madagascar

    NASA Astrophysics Data System (ADS)

    Melluso, L.; Cucciniello, C.; le Roex, A. P.; Morra, V.

    2016-07-01

    The Ankaratra volcanic complex in central Madagascar consists of lava flows, domes, scoria cones, tuff rings and maars of Cenozoic age that are scattered over 3800 km2. The mafic rocks include olivine-leucite-nephelinites, basanites, alkali basalts and hawaiites, and tholeiitic basalts. Primitive samples have high Mg# (>60), high Cr and Ni concentrations; their mantle-normalized patterns peak at Nb and Ba, have troughs at K, and smoothly decrease towards the least incompatible elements. The Ankaratra mafic rocks show small variation in Sr-Nd-Pb isotopic compositions (e.g., 87Sr/86Sr = 0.70377-0.70446, 143Nd/144Nd = 0.51273-0.51280, 206Pb/204Pb = 18.25-18.87). These isotopic values differ markedly from those of Cenozoic mafic lavas of northern Madagascar and the Comoro archipelago, typical Indian Ocean MORB and oceanic basalt end-members. The patterns of olivine nephelinitic magmas can be obtained through 3-10% partial melting of a mantle source that was enriched by a Ca-rich alkaline melt, and that contained garnet, carbonates and phlogopite. The patterns of tholeiitic basalts can be obtained after 10-12% partial melting of a source enriched with lower amounts of the same alkaline melt, in the spinel- (and possibly amphibole-) facies mantle, hence in volumes where carbonate is not a factor. The significant isotopic change from the northernmost volcanic rocks of Madagascar and those in the central part of the island implicates a distinct source heterogeneity, and ultimately assess the role of the continental lithospheric mantle as source region. The source of at least some volcanic rocks of the still active Comoro archipelago may have suffered the same time-integrated geochemical and isotopic evolution as that of the northern Madagascar volcanic rocks.

  5. Petrologic implications of plate tectonics.

    PubMed

    Yoder, H S

    1971-07-30

    Petrologists can make significant contributions to the plate tectonic concept. Fixing the stability fields of the principal rock types involved will provide the limits of pressure and temperature of the various environments. Experimental determination of the partition coefficients of the trace elements will be helpful. Studies of the partial melting behavior of possible parental materials in the absence and presence of water, especially the undersaturated region, will contribute to the understanding of magma production. Experimental observations on the rheological properties of the peridotites below and just above the solidus will lead to a better evaluation of the convective mechanism. Measurement of the fundamental properties of rocks, such as the density of solids and liquids at high pressures and temperatures, would contribute to understanding the concepts of diapiric rise, magma segregation, and the low-velocity zone. Broader rock sampling of the oceanic areas of all environments will do much to define the petrologic provinces. The field petrologist specializing in the Paleozoic regions and Precambrian shields can contribute by examining those regions for old plate boundaries and devising new criteria for their recognition.

  6. Genesis and Characteristics of Debris Flow Ocurred in 2013 in the Atenquique Ravine, Located on the Eastern Slope of the Colima Volcanic Complex, Mexico.

    NASA Astrophysics Data System (ADS)

    Suarez-Plascencia, C.; Flores-Pena, S.; Nunez-Cornu, F. J.; Arreola-Ochoa, L. C.; Suarez-Gonzalez, B. V.

    2014-12-01

    Hurricane Manuel affected the Pacific coast of Mexico on September 15 and 16, 2013 causing heavy rainfall of about 240 mm in a 24 hour period in the area of the Volcanic Complex (VC). Heavy rainfall led to the beginning of a significant flow of mud and rocks draining from the Atenquique Creek, located on the eastern slope of the VC in a west east direction. The result of this flow was the heavy damage sustained by the local paper plant located next to the town of Atenquique in the distal part of the basin where the stream is gathered by the Tuxpan River. Damages totaling over 15 million dollars affected a large part in their recycled fibers factory, resulting in an 18-month full stoppage of the factory. This in turn caused a heavy setback of the economy located within a large region of the southern state of Jalisco. Once again on November 25, debris flow occurred only at a lower volume than the September rains, without causing any damage. Both flows contained a viscous and solid liquid flow that left deposits of silt-sandy clasts and other abundant materials of reverse gradation. The first flow reached a thickness of 4.5 m in the Tuxpan riverbed over a length of about 15 km, while the November flow left behind 1.3 m of fine materials and few clasts. The Atenquique ravine historically has had debris flow caused by heavy rainfall from hurricanes. On October 1955 debris flow claimed many deaths and heavy damage to the town and local paper mill. These flows are generated in the summer and they are associated to several factors such as weather, steep slopes, unstable volcanic strata, these elements add an important environmental history in the area, as is the use of continuous deforestation. The current land use has resulted in a positive change from forest to intensive agriculture; but having constant wildfires on the high slopes of the VC and the combination of many other factors such as changes on the soil of the slopes and movement of geological material "scarps and

  7. Genesis Preliminary Examination: Ellipsometry Overview

    NASA Technical Reports Server (NTRS)

    Stansbery, E. K.; McNamara, K. M.

    2005-01-01

    The Genesis spacecraft returned to Earth on September 8, 2004, experiencing a non-nominal reentry in which both the drogue and main parachutes failed to deploy causing the capsule to impact the surface of the UTTR desert at a speed of approximately 310 kph (193 mph). The impact caused severe damage to the capsule and a breach of the science canister in the field. The science canister was recovered and transported to the cleanroom at UTTR within approximately 8 hours of reentry. Although the ground water table did not rise to canister level before removal, damp soil and debris from the heat shield and other spacecraft components did enter the canister and contaminate some collector surfaces. The objective of preliminary examination of the Genesis collectors is to provide the science community with the information necessary to request the most useful samples for their analysis.

  8. 76 FR 54454 - Issuance of Loan Guarantee to Genesis Solar, LLC, for the Genesis Solar Energy Project

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-01

    ... Issuance of Loan Guarantee to Genesis Solar, LLC, for the Genesis Solar Energy Project AGENCY: U.S... Genesis Solar, LLC, for construction and startup of the Genesis Solar Energy Project (GSEP), a 250... Statement for the Genesis Solar Energy Project, Riverside County, California (75 Federal Register...

  9. Petrologic Characteristics of the Lunar Surface

    NASA Astrophysics Data System (ADS)

    Wang, Xianmin; Pedrycz, Witold

    2015-11-01

    Petrologic analysis of the lunar surface is critical for determining lunar formation and evolution. Here, we report the first global petrologic map that includes the five most important lunar lithological units: the Ferroan Anorthositic (FAN) Unit, the Magnesian Suite (MS) Unit, the Alkali Suite (AS) Unit, the KREEP Basalt (KB) Unit and the Mare Basalt (MB) Unit. Based on the petrologic map and focusing on four long-debated and important issues related to lunar formation and evolution, we draw the following conclusions from the new insights into the global distribution of the five petrologic units: (1) there may be no petrogenetic relationship between MS rocks and KB; (2) there may be no petrogenetic link between MS and AS rocks; (3) the exposure of the KREEP component on the lunar surface is likely not a result of MB volcanism but is instead mainly associated with the combined action of plutonic intrusion, KREEP volcanism and celestial collision; (4) the impact size of the South Pole-Aitken basin is constrained, i.e., the basin has been excavated through the whole crust to exhume a vast majority of lower-crustal material and a very limited mantle components to the lunar surface.

  10. Petrologic Characteristics of the Lunar Surface

    PubMed Central

    Wang, Xianmin; Pedrycz, Witold

    2015-01-01

    Petrologic analysis of the lunar surface is critical for determining lunar formation and evolution. Here, we report the first global petrologic map that includes the five most important lunar lithological units: the Ferroan Anorthositic (FAN) Unit, the Magnesian Suite (MS) Unit, the Alkali Suite (AS) Unit, the KREEP Basalt (KB) Unit and the Mare Basalt (MB) Unit. Based on the petrologic map and focusing on four long-debated and important issues related to lunar formation and evolution, we draw the following conclusions from the new insights into the global distribution of the five petrologic units: (1) there may be no petrogenetic relationship between MS rocks and KB; (2) there may be no petrogenetic link between MS and AS rocks; (3) the exposure of the KREEP component on the lunar surface is likely not a result of MB volcanism but is instead mainly associated with the combined action of plutonic intrusion, KREEP volcanism and celestial collision; (4) the impact size of the South Pole-Aitken basin is constrained, i.e., the basin has been excavated through the whole crust to exhume a vast majority of lower-crustal material and a very limited mantle components to the lunar surface. PMID:26611148

  11. Petrologic Characteristics of the Lunar Surface.

    PubMed

    Wang, Xianmin; Pedrycz, Witold

    2015-11-27

    Petrologic analysis of the lunar surface is critical for determining lunar formation and evolution. Here, we report the first global petrologic map that includes the five most important lunar lithological units: the Ferroan Anorthositic (FAN) Unit, the Magnesian Suite (MS) Unit, the Alkali Suite (AS) Unit, the KREEP Basalt (KB) Unit and the Mare Basalt (MB) Unit. Based on the petrologic map and focusing on four long-debated and important issues related to lunar formation and evolution, we draw the following conclusions from the new insights into the global distribution of the five petrologic units: (1) there may be no petrogenetic relationship between MS rocks and KB; (2) there may be no petrogenetic link between MS and AS rocks; (3) the exposure of the KREEP component on the lunar surface is likely not a result of MB volcanism but is instead mainly associated with the combined action of plutonic intrusion, KREEP volcanism and celestial collision; (4) the impact size of the South Pole-Aitken basin is constrained, i.e., the basin has been excavated through the whole crust to exhume a vast majority of lower-crustal material and a very limited mantle components to the lunar surface.

  12. Mind Over Magma: The Story of Igneous Petrology

    NASA Astrophysics Data System (ADS)

    Snyder, Don

    2004-01-01

    In the centuries that enquiring minds have studied and theorized about igneous rocks, much progress has been made, both in accumulating observations and in developing theories. Yet, writing a history of this progress is a daunting undertaking. The volume of the literature is vast and in multiple languages; the various lines of inquiry are diverse and complex; and the nomenclature is sometimes abstruse. On top of these challenges, many of its principal issues have yet to find a definitive consensus. With the exception of a few topical studies, historians of science have virtually avoided the subject. In Mind Over Magma: The Story of Igneous Petrology, Davis Young has taken on the challenge of writing a comprehensive survey of the study of igneous rocks, and the result has been a remarkable book of meticulous scholarship. Igneous petrology is a vast subject, and it is not obvious how best to organize its history. Young takes a topical approach, generally grouping together various studies by either the problem being investigated or the method of attack. These topics span the earliest times to the present, with an emphasis on recurring themes, such as the causes of magmatic diversity and the origins of the granitic rocks. The range of topics includes most of the subjects central to the field over its history. As much as is practical, topics are discussed in chronological order, and along the way, the reader is treated to biographical sketches of many of the key contributors. This organization proves effective in dealing with the multitude of concepts.

  13. Improving Student Persistence at the Genesis Center

    ERIC Educational Resources Information Center

    Fritz, Nancy; Alsabek, Barbara Piccirilli

    2010-01-01

    The Genesis Center is a community-based adult education center located in Providence, Rhode Island. Founded in 1982 to assist immigrants and refugees from Southeast Asia in their transition to life in the United States, the Genesis Center now provides adult education, job training, and child care services to people who have immigrated from all…

  14. Petrological Mapping of the Crater Boguslawsky

    NASA Astrophysics Data System (ADS)

    Wöhler, C.; Evdokimova, N. A.; Feoktistova, E. A.; Grumpe, A.; Kapoor, K.; Berezhnoy, A. A.; Shevchenko, V. V.

    2015-10-01

    An analysis of orbital spectral data of the crater Boguslawsky, the intended target region of the Russian Luna-Glob mission, is performed. We have constructed a high- resolution DEM of the crater Boguslawsky, based on which the temperature regime on the surface is investigated. The depth of the OH absorption feature is analysed.The content of the main elements is estimated, and a petrologic map is constructed accordingly.

  15. Magmas and magmatic rocks: An introduction to igneous petrology

    SciTech Connect

    Middlemost, E.A.K.

    1986-01-01

    This book melds traditional igneous petrology with the emerging science of planetary petrology to provide an account of current ideas on active magmatic and volcanic processes, drawing examples from all igneous provinces of the world as well as from the moon and planets. It reviews the history and development of concepts fundamental to modern igneous petrology and includes indepth sections on magmas, magnetic differentiation and volcanology.

  16. Genesis: Sorting Out the Pieces

    NASA Technical Reports Server (NTRS)

    McNamara, K. M.; Westphal, Andrew; Butterworth, A. L.; Burnett, D. S.

    2005-01-01

    The Genesis mission returned to Earth on September 8, 2004, experiencing a non-nominal reentry. The parachutes which were supposed to slow and stabilize the capsule throughout the return failed to deploy, causing the capsule to impact the desert floor at a speed of nearly 200 MPH. The result is that instead of receiving 301 intact solar wind collectors, mission personnel recovered and documented more than 10,000 collector fragments. Most of the fragments were pieces of the collector arrays but were not recovered on their original array locations. These were classified by size (longest dimension), identity (sometimes a guess) and found location (when known). The work took more than one month in Utah, and details are discussed elsewhere[1] The samples were transferred to their permanent home at the Johnson Space Center on October 4, 2004.

  17. Solar composition from the Genesis Discovery Mission

    PubMed Central

    Burnett, D. S.; Team, Genesis Science

    2011-01-01

    Science results from the Genesis Mission illustrate the major advantages of sample return missions. (i) Important results not otherwise obtainable except by analysis in terrestrial laboratories: the isotopic compositions of O, N, and noble gases differ in the Sun from other inner solar system objects. The N isotopic composition is the same as that of Jupiter. Genesis has resolved discrepancies in the noble gas data from solar wind implanted in lunar soils. (ii) The most advanced analytical instruments have been applied to Genesis samples, including some developed specifically for the mission. (iii) The N isotope result has been replicated with four different instruments. PMID:21555545

  18. Textural and petrological characteristics of ultrahigh-pressure chromitites, indicating a mantle recycling origin?

    NASA Astrophysics Data System (ADS)

    Arai, Shoji; Miura, Makoto; Yamamoto, Shinji; Shmelev, Vladimir

    2013-04-01

    Podiform chromitites, which occur as irregular to lens-like chromite-rich bodies within mantle peridotite in ophiolites, show various petrological characteristics, suggesting various origins. Some of them contain ultrahigh-pressure (UHP) minerals such as diamond, moissanite and Fe silicides (= UHP chromitites) (e.g., Robinson et al., 2004; Yang et al., 2007). Their origin is highly enigmatic, because the podiform chromitites have been widely understood as low-P (uppermost mantle level) products (e.g., Arai and Yurimoto, 1994; Zhou et al., 1994). Ordinary podiform chromitites show various lines of evidence for low-P genesis. Chromian spinel (or chromite) frequently contains solid mineral inclusions, and one of their main phases is pargasite, which is stable up to 3 GPa (e.g., Niida and Green, 1999), one of typical low-P minerals. The melt-harzburgite intereaction is a fundamental process in podiform chromitite genesis (e.g., Arai and Yurimoto, 1994), and associated with incongruent melting of orthopyroxene in harzburgite to form dunite and relatively Si-rich melt, which is operative at low-P conditions (e.g., Kushiro, 1969). We are strongly required to incorporate the genesis UHP chromitite into the framework of podiform chromitite genesis. Arai (2010) proposed a hypothesis of deep mantle recycling of ordinary low-P chromitite for the genesis of UHP chromitite. We try to examine petrographical and petrological characteristics of UHP chromitites to check the hypothesis of Arai (2010). Some peculiar textures of podiform chromities, such as orbicular, nodular and anti-nodular textures, are interpreted to be primary igneous and particular to ordinary low-P igneous chromitites (cf. Nicolas, 1989). To be interesting, the nodular texture, characterized by oval aggregates of chromian spinel (= chromite nodules; ~1 cm across) set in olivine-rich matrix, is also observed in some of UHP chromitites from the Luobusa ophiolite, Tibet (e.g., Yamamoto et al., 2009). We carefully

  19. Genesis Halo Orbit Station Keeping Design

    NASA Technical Reports Server (NTRS)

    Lo, M.; Williams, K.; Wilson, R.; Howell, K.; Barden, B.

    2000-01-01

    As the fifth mission of NASA's Directory Program, Genesis is designed to collect solar wind samples for approximately two years in a halo orbit near the Sun-Earth L(sub 1) Lagrange point for return to the Earth.

  20. The Genesis of tectonically and hydrothermally controlled industry mineral deposits: A geochemical and structural study

    NASA Astrophysics Data System (ADS)

    Wölfler, Anke; Prochaska, Walter; Henjes-Kunst, Friedhelm; Fritz, Harald

    2010-05-01

    The study aims to investigate the role of hydrothermal fluids in the formation of talc and magnesite deposits. These deposits occur in manifold geological and tectonical settings such as stockworks and veins within ultramafite hostrocks and monomineralic lenses within marine platform sediments. Along shear zones talc mineralizations may occur as a result of tectonical and hydrothermal activity. To understand the role of the fluids for the genesis of the mineralization, deposits in different geological and tectonical settings are investigated: Talc mineralization within in magnesite in low-grade palaeozoic nappe complexes (Gemerska Poloma, Slovakia): The magnesite body lies within the Gemer unit of the Inner Carpathians consisting of Middle Triassic metacarbonates and Upper Triassic pelagic limestones and radiolarites. The talc mineralization is bound to crosscutting veins. Two metamorphic events can be distinguished, one during Variscan orogeny and one related to the Alpine orogeny leading to the formation of talc along faults in an Mg carbonate body (Radvanec et al, 2004).The origin of the fluids as well as the tectonic events leading to the mineralization is still widely unknown. Talc mineralization in shearzones within Palaeozoic meta sedimentary rocks (Sa Matta, Sardinia): Variscan granitoids intruded Palaeozoic meta sedimentary rocks and were overprinted be NE striking tectonic structures that host talc mineralizations. The origin of Mg and fluids leading to the mineralization is still not answered satisfactorily (Grillo and Prochaska, 2007) and thus a tectonic model for the genesis of the talc deposit is missing. Talc mineralization within UHP pre-Alpine continental crust (Val Chisone, Italy): The talc deposit forms part of the Dora-Maira Massif. Geologicaly the massif derived from a Variscan basement that includes post-Variscan intrusions. The talc mineralization occurs as a sheetlike, conformable body. A possible tectonic emplacement of talc along shear

  1. A genesis of special relativity

    NASA Astrophysics Data System (ADS)

    Messager, Valérie; Letellier, Christophe

    2015-07-01

    The genesis of special relativity is intimately related to the development of the theory of light propagation. When optical phenomena were described, there are typically two kinds of theories: (i) One based on light rays and light particles and (ii) one considering the light as waves. When diffraction and refraction were experimentally discovered, light propagation became more often described in terms of waves. Nevertheless, when attempts were made to explain how light was propagated, it was nearly always in terms of a corpuscular theory combined with an ether, a subtle medium supporting the waves. Consequently, most of the theories from Newton's to those developed in the 19th century were dual and required the existence of an ether. We therefore used the ether as our Ariadne thread for explaining how the principle of relativity became generalized to the so-called Maxwell equations around the 1900's. Our aim is more to describe how the successive ideas were developed and interconnected than framing the context in which these ideas arose.

  2. LCSs in tropical cyclone genesis

    NASA Astrophysics Data System (ADS)

    Rutherford, B.; Montgomery, M. T.

    2011-12-01

    The formation of tropical cyclones in the Atlantic most often occurs at the intersection of the wave trough axis of a westward propagating African easterly wave and the wave critical latitude. Viewed in a moving reference frame with the wave, a cat's eye region of cyclonic recirculation can be seen in streamlines prior to genesis. The cat's eye recirculation region has little strain deformation and its center serves as the focal point for aggregation of convectively generated vertical vorticity. Air inside the cat's eye is repeatedly moistened by convection and is protected from the lateral intrusion of dry air. Since the flow is inherently time-dependent, we contrast the time-dependent structures with Eulerian structures of the wave-relative frame. Time-dependence complicates the kinematic structure of the recirculation region as air masses from the outer environment are allowed to interact with the interior of the cat's eye. LCSs show different boundaries of the cat's eye than the streamlines in the wave-relative frame. These LCSs are particularly important for showing the pathways of air masses that interact with the developing vortex, as moist air promotes development by supporting deep convection, while interaction with dry air impedes development. We primarily use FTLEs to locate the LCSs, and show the role of LCSs in both developing and non-developing storms. In addition, we discuss how the vertical coherence of LCSs is important for resisting the effects of vertical wind shear.

  3. Crustal genesis and plate tectonics

    NASA Astrophysics Data System (ADS)

    Yang-shen, Shi; Shu-feng, Yang; Ling-zhi, Guo; Huo-gen, Dong

    1991-02-01

    As a transitional zone between ocean and continent, the continental margins are important accreted belts of the granitic crust. Extensive granitoids of different geological ages and different genetic series occur in the continental margins of southeastern China. The granites in active continental margins of southeast China are divided into two genetic series by present authors as follows:(1) S-type granitoids in the interior of the continental plate; and (2) I-type granitoids in the margin of the continental plate. S-type and I-type granitoids of almost the same geological age are paired and belted in their spatial distribution parallel to the continental margin. These are referred to as "paired granite belts". Granitic continental crust genesis is closely related to the growth of paired granite belts. In Mt. Yunkai of southeastern China, Guangdong province, Early Paleozoic S-type granitoids have been produced as a result of transformation of Cambrian sediments during the processes of metamorphism, migmatization, granitization and remelting. Co-magmatic volcanic rocks are completely lacking in this area. Early Paleozoic I-type granitoids on the east side of Mt. Yunkai are distributed along the ancient continental margin. These rocks co-exist with comagmatic island-arc volcanic rocks of calc-alkaline series in this area. The above mentioned two types of granitoids are paired and belted. Similar paired granite belts exist around the world, such as in North America and southeastern Australia, and are interpreted to be products of post plate convergence, subduction and collision.

  4. The Genesis of the AFMLTA and Babel and the Babel of Genesis

    ERIC Educational Resources Information Center

    Vale, David

    2006-01-01

    In this article, the author describes the genesis of the Australian Federation of Modern Language Teachers Associations (AFMLTA) and "Babel." With regard to the origin of the title of the journal, its name refers only indirectly to the Tower of Babel in Genesis. It comes in fact from the affectionate nickname that had been given to the…

  5. Mineralogy, petrology and chemistry of ANT-suite rocks from the lunar highlands

    NASA Technical Reports Server (NTRS)

    Prinz, M.; Keil, K.

    1977-01-01

    Anorthositic-noritic-troctolitic (ANT) rocks are the oldest and most abundant rocks of the lunar surface, and comprise about 90% of the suite of the lunar highlands. Consideration is given to the mineralogy, petrology, bulk chemistry, and origin of ANT-suite rocks. Problems associated in classifying and labeling lunar highland rocks because of textural complexities occurring from impact modifications are discussed. The mineralogy of ANT-suite rocks, dominated by plagioclase, olivine and pyrozene, and containing various minor minerals, is outlined. The petrology of ANT-suite rocks is reviewed along with the major element bulk composition of these rocks, noting that they are extremely depleted in K2O and P2O5. Various models describing the origin of ANT-suite rocks are summarized, and it is suggested that this origin involves a parental liquid of high-alumina basalt with low Fe/Fe+Mg.

  6. [Petrological Analysis of Astrophysical Dust Analog Evolution

    NASA Technical Reports Server (NTRS)

    Rietmeijer, Frans J. M.

    1997-01-01

    This project "Petrological analysis of astrophysical dust analog evolution" was initiated to try to understand the vapor phase condensation, and the nature of the reaction products, in circumstellar environments, such as the solar nebula 4,500 Myrs ago, and in the interstellar medium. Telescope-based infrared [IR] spectroscopy offers a broad-scale inventory of the various types of dust in these environments but no details on small-scale variations in terms of chemistry and morphology and petrological phase relationships. Vapor phase condensation in these environments is almost certainly a non-equilibrium process. The main challenge to this research was to document the nature of this process that, based on astrophysical observations, seems to yield compositionally consistent materials. This observation may suggest a predictable character during non-equilibrium condensation. These astrophysical environments include two chemically distinct, that is, oxygen-rich and carbon-rich environments. The former is characterized by silicates the latter by carbon-bearing solids. According to cosmological models of stellar evolution circumstellar dust accreted into protoplanets wherein thermal and/or aqueous processes will alter the dust under initially, non-equilibrium conditions.

  7. Modeling petrological geodynamics in the Earth's mantle

    NASA Astrophysics Data System (ADS)

    Tirone, M.; Ganguly, J.; Morgan, J. P.

    2009-04-01

    We have developed an approach that combines principles of fluid dynamics and chemical thermodynamics into a fully coupled scheme to model geodynamic and petrological evolution of the Earth's mantle. Transport equations involving pressure, temperature, velocities, and bulk chemical composition are solved for one or more dynamic phases and interfaced with the thermodynamic solutions for equilibrium mineralogical assemblages and compositions. The mineralogical assemblage and composition are computed on a space-time grid, assuming that local thermodynamic equilibrium is effectively achieved. This approach allows us to simultaneously compute geophysical, geochemical, and petrological properties that can be compared with a large mass of observational data to gain insights into a variety of solid Earth problems and melting phenomena. We describe the salient features of our numerical scheme and the underlying mathematical principles and discuss a few selected applications to petrological and geophysical problems. First, it is shown that during the initial stage of passive spreading of plates, the composition of the melt near Earth's surface is in reasonable agreement with the average major element composition of worldwide flood basalts. Only the silica content from our model is slightly higher that in observational data. The amount of melt produced is somewhat lower than the estimated volumes for extrusive and upper crustal intrusive igneous rocks from large igneous provinces suggesting that an active upwelling of a larger mantle region should be considered in the process. Second, we have modeled a plume upwelling under a moving plate incorporating the effects of mineralogy on the density structure and viscous dissipation on the heat transport equation. The results show how these effects promote mantle instability at the base of the lithosphere. Third, we have considered a mantle convection model with viscosity and density directly related to the local equilibrium

  8. Genesis Capsule Yields Solar Wind Samples

    NASA Astrophysics Data System (ADS)

    Wiens, Roger C.; Burnett, Donald S.; Stansbery, Eileen K.; McNamara, Karen M.

    2004-11-01

    NASA's Genesis capsule, carrying the first samples ever returned from beyond the Moon, took a hard landing in the western Utah desert on 8 September after its parachutes failed to deploy. Despite the impact, estimated at 310 km per hour, some valuable solar wind collector materials have been recovered. With these samples, the Genesis team members are hopeful that nearly all of the primary science goals may be met. The Genesis spacecraft was launched in August 2001 to collect and return samples of solar wind for precise isotopic and elemental analysis. The spacecraft orbited the Earth-Sun Lagrangian point (L1), ~1.5 million km sunward of the Earth, for 2.3 years. It exposed ultrapure materials-including wafers of silicon, silicon carbide, germanium, chemically deposited diamond, gold, aluminum, and metallic glass-to solar wind ions, which become embedded within the substrates' top 100 nm of these materials.

  9. Thermal and petrologic constraints on the lower crustal melt accumulation in the Salton Sea Geothermal Field

    NASA Astrophysics Data System (ADS)

    Karakas, O.; Dufek, J.; Mangan, M.; Wright, H. M. N.

    2014-12-01

    Heat transfer in active volcanic areas is governed by complex coupling between tectonic and magmatic processes. These two processes provide unique imprints on the petrologic and thermal evolution of magma by controlling the geometry, depth, longevity, composition, and fraction of melt in the crust. The active volcanism, tectonic extension, and significantly high surface heat flow in Salton Sea Geothermal Field, CA, provides information about the dynamic heat transfer processes in its crust. The volcanism in the area is associated with tectonic extension over the last 500 ka, followed by subsidence and sedimentation at the surface level and dike emplacement in the lower crust. Although significant progress has been made describing the tectonic evolution and petrology of the erupted products of the Salton Buttes, their coupled control on the crustal heat transfer and feedback on the melt evolution remain unclear. To address these concepts, we develop a two-dimensional finite volume model and investigate the compositional and thermal evolution of the melt and crust in the Salton Sea Geothermal Field through a one-way coupled thermal model that accounts for tectonic extension, lower crustal magma emplacement, sedimentation, and subsidence. Through our simulations, we give quantitative estimates to the thermal and compositional evolution and longevity of the lower crustal melt source in the crustal section. We further compare the model results with petrologic constraints. Our thermal balance equations show that crustal melting is limited and the melt is dominated by mantle-derived material. Similarly, petrologic work on δ18O isotope ratios suggests fractional crystallization of basalt with minor crustal assimilation. In addition, we suggest scenarios for the melt fraction, composition, enthalpy release, geometry and depth of magma reservoirs, their temporal evolution, and the timescales of magmatic storage and evolution processes. These parameters provide the source

  10. Petrology of brecciated ferroan noritic anorthosite 67215

    NASA Technical Reports Server (NTRS)

    Mcgee, James J.

    1988-01-01

    A petrologic study of breccia 67215 is presented, showing that the rock has the bulk composition of a ferroan noritic anorthosite and is a polymict breccia containing several lithic clast types within a crushed, cataclastic matrix. The dominant lithic clasts contained in breccia 67215 are found to be igneous and metamorphic low- and high- Ca pyroxenes and olivine. Other clasts include granulated and sheared clasts, coarse-grained anorthosite with relatively Fe-rich augite, aphanitic, feldspathic microporphyritic melt breccias, and an impact-melt rock with strongly zoned relatively Mg-rich pyroxene. It is concluded that this rock type is relatively common in the highlands regolith excavated by the North Ray Crater.

  11. Petrology and Composition of HED Polymict Breccias

    NASA Technical Reports Server (NTRS)

    Mittlefehldt, David W.; Herrin, J. S.; Mertzman, S. A.; Mertzman, K. R.

    2010-01-01

    The howardite, eucrite and diogenite (HED) clan of meteorites forms the largest suite of achondrites with over 900 named members. The HEDs are igneous rocks and breccias of igneous rocks from a differentiated asteroid [1]. The consensus view is that these rocks hail from the asteroid 4 Vesta, which will be the first target of NASA's Dawn mission. When Dawn arrives at Vesta, she will begin remote imagery and spectroscopy of the surface. The surface she will observe will be dominated by rocks and soils mixed through impact gardening. To help with the interpretation of the remotely sensed data, we have begun a project on the petrologic and compositional study of a suite of HED polymict breccias. Here we report on the preliminary findings of this project.

  12. A Virtual Petrological Microscope for All Apollo 11 Lunar Samples

    NASA Technical Reports Server (NTRS)

    Pillnger, C. T.; Tindle, A. G.; Kelley, S. P.; Quick, K.; Scott, P.; Gibson, E. K.; Zeigler, R. A.

    2014-01-01

    A means of viewing, over the Internet, polished thin sections of every rock in the Apollo lunar sample collections via software, duplicaing many of the functions of a petrological microscope, is described.

  13. Generalized Galileons: instabilities of bouncing and Genesis cosmologies and modified Genesis

    NASA Astrophysics Data System (ADS)

    Libanov, M.; Mironov, S.; Rubakov, V.

    2016-08-01

    We study spatially flat bouncing cosmologies and models with the early-time Genesis epoch in a popular class of generalized Galileon theories. We ask whether there exist solutions of these types which are free of gradient and ghost instabilities. We find that irrespectively of the forms of the Lagrangian functions, the bouncing models either are plagued with these instabilities or have singularities. The same result holds for the original Genesis model and its variants in which the scale factor tends to a constant as t → -∞. The result remains valid in theories with additional matter that obeys the Null Energy Condition and interacts with the Galileon only gravitationally. We propose a modified Genesis model which evades our no-go argument and give an explicit example of healthy cosmology that connects the modified Genesis epoch with kination (the epoch still driven by the Galileon field, which is a conventional massless scalar field at that stage).

  14. Generalized Galileons: instabilities of bouncing and Genesis cosmologies and modified Genesis

    SciTech Connect

    Libanov, M.; Mironov, S.; Rubakov, V.

    2016-08-18

    We study spatially flat bouncing cosmologies and models with the early-time Genesis epoch in a popular class of generalized Galileon theories. We ask whether there exist solutions of these types which are free of gradient and ghost instabilities. We find that irrespectively of the forms of the Lagrangian functions, the bouncing models either are plagued with these instabilities or have singularities. The same result holds for the original Genesis model and its variants in which the scale factor tends to a constant as t→−∞. The result remains valid in theories with additional matter that obeys the Null Energy Condition and interacts with the Galileon only gravitationally. We propose a modified Genesis model which evades our no-go argument and give an explicit example of healthy cosmology that connects the modified Genesis epoch with kination (the epoch still driven by the Galileon field, which is a conventional massless scalar field at that stage).

  15. Interactive Storytelling: From the Book of Genesis

    ERIC Educational Resources Information Center

    Park, Keith

    2004-01-01

    Keith Park, advisory teacher for Sense (the National Deafblind Rubella Association) in Greenwich and Lewisham, London, has written about his approach to interactive storytelling for BJSE before. This article describes a series of poetry workshops based on chapters 37 to 45 of the Book of Genesis (the story of Joseph and his family) using the text…

  16. Grants: Genesis of Some Funded Proposal Ideas

    ERIC Educational Resources Information Center

    Pazdar, John

    2011-01-01

    While "thinking outside the box" can be an over-used phase at times, in the world of grants it can provide the genesis of ideas. The "box" is the world of academia accepted by most educators, while "thinking outside" is the process that leads to grant ideas. In the grant world, "thinking outside the box" is a process of doing something that has…

  17. Solar Wind Elemental Abundances from GENESIS Collectors

    NASA Astrophysics Data System (ADS)

    Burnett, D. S.; Woolum, D. S.; Jurewicz, A. J. G.; McKeegan, K. D.; Guan, Y.

    2007-03-01

    GENESIS bulk solar wind analyses were made by SIMS on Si, Sandia diamond-like-C, and epitaxial Si on sapphire (SoS). Preliminary Fe, Mg, Ca, Cr and Na fluences are calculated. The eventual goal is to test for fractionation (or lack thereof) of solar-wind

  18. The Genesis Trajectory and Heteroclinic Cycles

    NASA Technical Reports Server (NTRS)

    Lo, M.; Koon, W.; Ross, S.; Marsden, J.

    1999-01-01

    The Genesis Mission will be NASA's first robotic sample return mission. The purpose of this mission is to collect solar wind samples for two years in L1 halo orbit and return it to the Utah Test and Training Range (UTTR) for mid-air retrieval by helicopters.

  19. Finding the Genesis for a Thesis

    ERIC Educational Resources Information Center

    Caroll, Joyce Armstrong

    2013-01-01

    This article describes a prewriting heuristics strategy that can help students find the genesis of their thesis. The 3 functions of the heuristic procedure are that it aids in retrieving relevant information stored in the mind; draws attention to important information that can be further researched or accessed; and prepares the mind for the…

  20. Gender-transposition theory and homosexual genesis.

    PubMed

    Money, J

    1984-01-01

    The genesis of homosexuality, and therefore of heterosexuality also, has traditionally been argued as either wholly biological or wholly social-environmental. The theory of gender transposition integrates findings regarding both prenatal hormonal programming of the sexual brain, and postnatal social programming.

  1. From static to dynamic provenance analysis-Sedimentary petrology upgraded

    NASA Astrophysics Data System (ADS)

    Garzanti, Eduardo

    2016-05-01

    The classical approach to sandstone petrology, established in the golden years of plate tectonics and based on the axiom that "detrital modes of sandstone suites primarily reflect the different tectonic settings of provenance terranes," has represented a benchmark for decades. The composition of sand and sandstone, however, simply provides us with a distorted image of the lithological structure of source terranes and gives us little clue whether they are allochthonous or autochthonous, orogenic or anorogenic, young or old. What we may able to see reflected in detrital modes is the nature of source terranes (continental, arc, oceanic) and the tectonostratigraphic level reached by erosion in space and time. The proposed new approach to the petrology of sand and sandstone (1) starts with a simple classification scheme circulated since the 1960s, which is purely descriptive, objective, and free of ill-defined ambiguous terms and (2) focuses on the nature and tectonostratigraphic level of source terranes. Further steps are essential to upgrade provenance analysis. Acquiring knowledge from modern settings is needed to properly identify and wherever possible correct for physical and chemical processes introducing environmental and diagenetic bias and thus address nature's complexities with adequate conceptual tools. Equally important is the integration of multiple techniques, ideally including bulk-sediment, multi-mineral, and single-mineral methods. Bulk-sediment petrography remains the fundamental approach that allows us to capture the most precious source of direct provenance information, represented by the mineralogy and texture of rock fragments. Bulk-sediment geochemistry, applicable also to silt and clay carried in suspension, is a superior method to check for hydraulic sorting, chemical weathering, and fertility of detrital minerals in different sediment sources. Detrital geochronology, thermochronology, and isotope geochemistry reveal the diverse time structures

  2. A virtual petrological microscope for teaching and outreach

    NASA Astrophysics Data System (ADS)

    Kelley, Simon P.; Whalley, Peter; Tindle, Andrew G.; Anand, Mahesh

    2010-05-01

    Learning to use microscopes for geoscience or life science applications is a crucial part of the practical training offered in many science degrees, but the opportunities to study are often constrained by available laboratory space and time, and sometimes constrained by the number of high quality microscopes available. The alternative, although not replacing physical microscopes, offers the opportunity for enhancement and enrichment of laboratory experience in geoscience. An on-line microscope can also be used to engage the public with access to rare rocks such as meteorites and lunar samples. The focus of petrological microscope study in higher education is not primarily related to learning facts but is concerned with learning how to discriminate and classify within the paradigms of the discipline. In this case, the recognition and measurement of key features in rock samples in hand specimen and thin section. Whilst undertaking the practical exercise of recognition and naming of rock samples students are really being required to develop an understanding of the rock cycle as a model representing the relationship between rock categories and the process of their formation. The problems of teaching with complex visual materials, in effect of teaching learners 'how to see' from the scientific perspective of a particular discipline, are quite general. It could reasonably be expected that lessons learnt from the implementation and detailed evaluation of the proposed web-based system will generalise to many other topics in science education. Thus we focussed on the thin section images rather than reproducing a system that resembled a physical microscope. The virtual petrological microscope developed for a course at the Open University UK enables student acquisition of skills such as mineral and rock recognition using a browser window to explore thin sections of rocks as if they were using a laboratory microscope. The microscope allows students to pan around the thin

  3. Petrology and radiogeology of the Stripa pluton

    SciTech Connect

    Wollenberg, Harold; Flexser, Steve; Andersson, Lennart

    1980-12-01

    To better define the character of the rock encompassing the thermomechanical and hydrological experiments at the Stripa mine in central Sweden, and to help determine the size of the Stripa pluton, detailed studies were conducted of the petrology and radiogeology of the quartz monzonite and adjacent rocks. Petrologic studies emphasized optical petrography, with supplementary X-ray diffraction, X-ray fluorescence and microprobe analyses. Radiogeologic investigations were based primarily on surface and underground gamma-ray spectrometric measurements of uranium, thorium and potassium, supplemented by laboratory gamma spectrometric analyses and fission-track radiographic determinations of the locations and abundance of uranium in the rock matrix. Both the quartz monzonite and the metavolcanic leptite which it intruded are strongly fractured. Two stages of fracture filling are evident; an earlier stage encompassing quartz, sericite, feldspar, epidote, and chlorite, and a later stage dominated by carbonate minerals. The Stripa quartz monzonite is chemically and mineralogically distinct from other plutons in the region. Muscovite is the predominant mica in the quartz monzonite; biotite has been altered to chlorite, hornblende is absent, and accessory minerals are scarce. In contrast, in other plutons in the Stripa region biotite and hornblende are prominent mafic minerals and accessory minerals are abundant. The Stripa quartz monzonite is also considerably more radioactive than the leptite and other plutons in the region. Uranium and thorium abundances are both- 30 ppm, considerably higher than in "normal" granitic rocks where the thorium-to-uranium ratio generally exceeds 2. Potassium-argon dating of muscovite from the Stripa quartz monzonite indicates that this rock may be older, at 1691 million years than granitic rock of the neighboring Gusselby and Kloten massifs, whose ages, based on K-Ar dating of biotite, are respectively 1604 and 1640 m.y. Heat flow and heat

  4. The lunar regolith - Chemistry, mineralogy, and petrology

    NASA Technical Reports Server (NTRS)

    Papike, J. J.; Simon, S. B.; Laul, J. C.

    1982-01-01

    The data base on the lunar regolith is surveyed to form a synthesis of the lunar regolith chemistry, mineralogy, and petrology. The data were derived from samples collected by the Apollo missions 11-17 and the Luna 16, 20, and 24 probes. The missions were sent to sample formations and areas which typified the common observed features of the lunar surface. Drive tubes were used to extract samples from beneath the surface in order to study the relationship between the regolith and the bedrock, as well as to identify the processes that formed the regolith, which is regarded as the prime source of raw materials for early lunar industrial activities. Regolith origins are now understood to be destructive processes of comminution and constructional processes of agglutinate formation. Mixing occurs on the local scale, although lateral transport is inefficient on the moon. The usual contents of the fraction of regolith less than 10 microns in diameter are Al2O3, CaO, Na2O, K2O, light REE, and Th.

  5. Cratonization: a thermal and petrological perspective

    SciTech Connect

    Pollack, H.N.

    1985-01-01

    The long term thermal and tectonic history of the continental lithosphere derives from the processes that lead to crationization. Cratons are characterized by mechanical stability, buoyancy and freeboard, a paucity of magmatism, and deep roots. The process is not slow and gradual, extending over aeons, but rather is relatively rapid, being accomplished in a period on the order of 300-500 Ma; cratonic nuclei existed by the end of the Archean. The essential process is devolatilization of the upper mantle, in associations with major orogenic events, to a depth of about 300 km. Devolatilization has the following effects: 1) it elevates the solidus of the affected lithosphere, making it less vulnerable to subsequent melting, 2) it augments the mechanical strength and stiffness of the region by increasing the activation energy, thereby 3) enhancing the structural stability of the lithosphere, thickening it, and extending to greater depths the region in which conduction is the principal mode of heat transfer, thereby 4) maintaining freeboard by the thermal expansion of the extended lithosphere because of the higher temperatures of the conductive thermal regime, and 5) enhancement of buoyancy by thermal expansion and petrological differentiation. The process of cratonization can be reversed by reintroduction of volatiles for the deeper mantle, or by raising the temperature sufficiently to reach the volatile-free refractory solidus. Mantle metasomatic processes probably promote destabilization by recharging the thick need lithosphere with both volatiles and heat producing isotopes.

  6. Genesis Reentry Observations and Data Analysis

    NASA Technical Reports Server (NTRS)

    Suggs, R. M.; Swift, W. R.

    2005-01-01

    The Genesis spacecraft reentry represented a unique opportunity to observe a "calibrated meteor" from northern Nevada. Knowing its speed, mass, composition, and precise trajectory made it a good subject to test some of the algorithms used to determine meteoroid mass from observed brightness. It was also a good test of an inexpensive set of cameras that could be deployed to observe future shuttle reentries. The utility of consumer-grade video cameras was evident during the STS-107 accident investigation, and the Genesis reentry gave us the opportunity to specify and test commercially available cameras that could be used during future reentries. This Technical Memorandum describes the video observations and their analysis, compares the results with a simple photometric model, describes the forward scatter radar experiment, and lists lessons learned from the expedition and implications for the Stardust reentry in January 2006 as well as future shuttle reentries.

  7. GENESIS OF MITOCHONDRIA IN INSECT FAT BODY

    PubMed Central

    Larsen, W. J.

    1970-01-01

    Electron microscopy and stereological methods have been used to study the time course and mechanism of mitochondrial genesis in the adult fat body of Calpodes ethlius, (Lepidoptera, Hesperiidae). Most of the larval mitochondria are destroyed during a phase of autolysis shortly before pupation, so that pupal and early adult fat body cells have few mitochondria. The number of mitochondria per cell increases rapidly at the end of the 1st day after the adult emerges. Characteristic partitioned mitochondria appear during the period when the number is rapidly increasing. This evidence, coupled with the results of morphometric analyses of mitochondrial diameter, volume, and surface area, confirms the view that the genesis of adult mitochondria involves the growth and division of mitochondria surviving from the larva. PMID:19866737

  8. Slip rate and tremor genesis in Cascadia

    USGS Publications Warehouse

    Wech, Aaron G.; Bartlow, Noel M.

    2014-01-01

    At many plate boundaries, conditions in the transition zone between seismogenic and stable slip produce slow earthquakes. In the Cascadia subduction zone, these events are consistently observed as slow, aseismic slip on the plate interface accompanied by persistent tectonic tremor. However, not all slow slip at other plate boundaries coincides spatially and temporally with tremor, leaving the physics of tremor genesis poorly understood. Here we analyze seismic, geodetic, and strainmeter data in Cascadia to observe for the first time a large, tremor-generating slow earthquake change from tremor-genic to silent and back again. The tremor falls silent at reduced slip speeds when the migrating slip front pauses as it loads the stronger adjacent fault segment to failure. The finding suggests that rheology and slip-speed-regulated stressing rate control tremor genesis, and the same section of fault can slip both with and without detectable tremor, limiting tremor's use as a proxy for slip.

  9. Thermal structure of the lithosphere: a petrologic model.

    PubMed

    Macgregor, I D; Basu, A R

    1974-09-20

    A preliminary evaluation of the thermal history of the upper mantle as determined by petrologic techniques indicates a general correspondence with theoretically derived models. The petrologic data supply direct information which may be used as an independent calibration of calculated models, serve as a base for evaluating the assumptions of the theoretical approach, and allow more careful selection of the variables describing mantle thermal properties and processes. Like the theoretical counterpart, the petrological approach indicates that the lithosphere is dominated by two thermal regimes: first, there is a continental regime which cools at rates of the order of 10(9) years and represents the longterm cooling of the earth. Secondly, superimposed on the continental evolution is the thermal event associated with the formation of an oceanic basin, and which may be thought of as a 10(8) year convective perturbation on the continental cycle. Of special interest is petrologic evidence for a sudden steepening of the thermal gradients across the lithosphere-asthenosphere boundary not seen in the theoretical models. The unexpected change of slope points to the need for a critical reevaluation of the thermal processes and properties extant in the asthenosphere. The potential of the petrologic contribution has yet to be fully realized. For a start, this article points to an important body of independent evidence critical to our understanding of the earth's thermal history.

  10. Petrology and In Situ Trace Element Chemistry of a Suite of R Chondrites

    NASA Astrophysics Data System (ADS)

    Mittlefehldt, D. W.; Peng, Z. X.; Torrano, Z. A.

    2015-07-01

    Your eyes are not deceiving you: Duck has submitted an abstract to a chondrite session. We will present the results of our petrological and compositional studies of R chondrites of diverse petrological type.

  11. Cleaning Study of Genesis Sample 60487

    NASA Technical Reports Server (NTRS)

    Kuhlman, Kim R.; Rodriquez, M. C.; Gonzalez, C. P.; Allton, J. H.; Burnett, D. S.

    2013-01-01

    The Genesis mission collected solar wind and brought it back to Earth in order to provide precise knowledge of solar isotopic and elemental compositions. The ions in the solar wind were stopped in the collectors at depths on the order of 10 to a few hundred nanometers. This shallow implantation layer is critical for scientific analysis of the composition of the solar wind and must be preserved throughout sample handling, cleaning, processing, distribution, preparation and analysis. Particles of Genesis wafers, brine from the Utah Testing Range and an organic film have deleterious effects on many of the high-resolution instruments that have been developed to analyze the implanted solar wind. We have conducted a correlative microscopic study of the efficacy of cleaning Genesis samples with megasonically activated ultrapure water and UV/ozone cleaning. Sample 60487, the study sample, is a piece of float-zone silicon from the B/C array approximately 4.995mm x 4.145 mm in size

  12. Trajectory Reconstruction for the Genesis Entry

    NASA Technical Reports Server (NTRS)

    Desai, Prasun N.; Qualls, Garry D.; Schoenenberger, Mark

    2005-01-01

    An overview of the reconstruction analyses performed for the Genesis capsule entry is described. The results indicate that the actual entry prior to the drogue deployment failure was very close to the pre-entry predictions. The capsule landed 8.3 km south of the desired target at Utah Test and Training Range. Analysis on infrared video footage (obtained from the tracking stations) during the descent estimated the onset of the capsule tumble at Mach 0.9. Frequency analysis on the infrared video data indicates that the aerodynamics generated for the Genesis capsule reasonably predicted the drag and static stability. Observations of the heatshield support the pre-entry simulation estimates of a small hypersonic angles-of-attack, since there is very little, if any, charring of the shoulder region or the afterbody. Through this investigation, an overall assertion can be made that all the data gathered from the Genesis entry is consistent with flight performance close to the nominal pre-entry prediction. Consequently, the design principles and methodologies utilized for the flight dynamics, aerodynamics, and aerothermodynamics analyses have been corroborated.

  13. Petrologic evolution of the Louisville seamount chain

    NASA Astrophysics Data System (ADS)

    Hawkins, James W.; Lonsdale, Peter F.; Batiza, Rodey

    mantle source for the LSC seamounts remained remarkably homogeneous through the ˜66 m.y. recorded history of the chain. This is also supported by Nd and Sr isotope data for these samples. The mantle source must have been enriched in elements such as K, Rb, Ba, Y, REE relative to the source for N-MORB or to "primitive" mantle. The LSC seamounts have evolved through a petrologic sequence like that of the Hawaiian and Samoan Chains, but the long term homogeneity of the mantle source of LSC mag mas is in marked contrast to the heterogeneous mantle implied by the petrology of Hawaiian and Samoan volcanoes. A hotspot origin for the LSC seems likely: there may be an active "Loihi counterpart" yet to be found at the southeastern end of the chain.

  14. On the Basic Principles of Igneous Petrology

    NASA Astrophysics Data System (ADS)

    Marsh, B. D.

    2014-12-01

    How and why Differentiation occurs has dominated Igneous Petrology since its beginning (~1880) even though many of the problems associated with it have been thoroughly solved. Rediscovery of the proverbial wheel with new techniques impedes progress. As soon as thin section petrography was combined with rock and mineral chemistry, rock diversity, compositional suites, and petrographic provinces all became obvious. The masterful 1902 CIPW norm in a real sense solved the chemical mystery of differentiation: rocks are related by the addition and subtraction of minerals in the anciently appreciated process of fractional crystallization. Yet few believed this, even after phase equilibria arrived. Assimilation, gas transfer, magma mixing, Soret diffusion, immiscibility, and other processes had strong adherents, even though by 1897 Becker conclusively showed the ineffectiveness of molecular diffusion in large-scale processes. The enormity of heat to molecular diffusion (today's Lewis no.) should have been convincing; but few paid attention. Bowen did, and he refined and restated the result; few still paid attention. And in spite of his truly masterful command of experiment and field relations in promoting fractional crystallization, Fenner and others fought him with odd arguments. The beauty of phase equilibria eventually dominated at the expense of knowing the physical side of differentiation. Bowen himself saw and struggled with the connection between physical and chemical processes. Progress has come from new concepts in heat transfer, kinetics, and slurry dynamics. The key approach is understanding the dynamic competition between spatial rates of solidification and all other processes. The lesson is clear: Scholarship and combined field, laboratory and technical expertise are critical to understanding magmatic processes. Magma is a limitlessly enchanting and challenging material wherein physical processes buttressed by chemistry govern.

  15. Possible petrological controls on the location and time scale of slow slip in SW Japan

    NASA Astrophysics Data System (ADS)

    Wallis, S.; Mizukami, T.; Yokoyama, H.; Hiramatsu, Y.; Arai, S.; Kawahara, H.; Nagaya, T.

    2014-12-01

    To examine the possibility that there was a petrological control on the location and nature of episodic tremor and slip (ETS), we compared the petrological characteristics of wedge mantle material to the results of recent geophysical observations in the Shikoku area, southwest Japan. This study revealed a close relationship between predicted mineral assemblages in the mantle wedge and the characteristics of slow slip behaviour recorded in the Shikoku area: Short-term ETSs take place in the antigorite +olivine stability field and silent long-term slow slip events (SSEs) take place in the antigorite+brucite stability field. The petrology of the mantle wedge may be an important control on the fluid pressure along the subduction interface and influence the time scales of SSEs. The Cretaceous Sanbagawa oceanic subduction complex of SW Japan preserves fragments of the former mantle wedge in contact with subducted slab units. P-T paths and peak P-T conditions show this belt formed as the result of subduction of a young slab under relatively warm conditions. These characteristics make the Sanbagawa belt a good analogue to modern warm subduction zones such as the Philippine Sea subduction zone beneath SW Japan and offer the possibility of directly examining the former plate boundary. Mantle wedge units derived from shallow depths show evidence for widely developed primary brucite and antigorite. In contrast, units derived from greater depths and higher peak temeratures consist dominantly of antigorite and olivine. Observations of the natural serpentinites suggest that the shallow serpentinite with brucite shows higher absorbency of water and provides fluid pathways that can reduce the fluid pore pressure on the subduction boundary.

  16. The roles of fractional crystallization, magma mixing, crystal mush remobilization and volatile-melt interactions in the genesis of a young basalt-peralkaline rhyolite suite, the greater Olkaria volcanic complex, Kenya Rift valley

    USGS Publications Warehouse

    Macdonald, R.; Belkin, H.E.; Fitton, J.G.; Rogers, N.W.; Nejbert, K.; Tindle, A.G.; Marshall, A.S.

    2008-01-01

    The Greater Olkaria Volcanic Complex is a young (???20 ka) multi-centred lava and dome field dominated by the eruption of peralkaline rhyolites. Basaltic and trachytic magmas have been erupted peripherally to the complex and also form, with mugearites and benmoreites, an extensive suite of magmatic inclusions in the rhyolites. The eruptive rocks commonly represent mixed magmas and the magmatic inclusions are themselves two-, three- or four-component mixes. All rock types may carry xenocrysts of alkali feldspar, and less commonly plagioclase, derived from magma mixing and by remobilization of crystal mushes and/or plutonic rocks. Xenoliths in the range gabbro-syenite are common in the lavas and magmatic inclusions, the more salic varieties sometimes containing silicic glass representing partial melts and ranging in composition from anorthite ?? corundum- to acmite-normative. The peralkaline varieties are broadly similar, in major element terms, to the eruptive peralkaline rhyolites. The basalt-trachyte suite formed by a combination of fractional crystallization, magma mixing and resorption of earlier-formed crystals. Matrix glass in metaluminous trachytes has a peralkaline rhyolitic composition, indicating that the eruptive rhyolites may have formed by fractional crystallization of trachyte. Anomalous trace element enrichments (e.g. ??? 2000 ppm Y in a benmoreite) and negative Ce anomalies may have resulted from various Na- and K-enriched fluids evolving from melts of intermediate composition and either being lost from the system or enriched in other parts of the reservoirs. A small group of nepheline-normative, usually peralkaline, magmatic inclusions was formed by fluid transfer between peralkaline rhyolitic and benmoreitic magmas. The plumbing system of the complex consists of several independent reservoirs and conduits, repeatedly recharged by batches of mafic magma, with ubiquitous magma mixing. ?? The Author 2008. Published by Oxford University Press. All

  17. 76 FR 73748 - Genesis Capital, LLC and Northern Lights Fund Trust; Notice of Application

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-29

    ... From the Federal Register Online via the Government Publishing Office SECURITIES AND EXCHANGE COMMISSION Genesis Capital, LLC and Northern Lights Fund Trust; Notice of Application November 21, 2011... approval. Applicants: Genesis Capital, LLC (``Genesis Capital'' or the ``Adviser'') and Northern...

  18. Numerical Models of Ophiolite Genesis and Obduction

    NASA Astrophysics Data System (ADS)

    Guilmette, C.; Beaumont, C.; Jamieson, R.

    2013-12-01

    Ophiolites are relics of oceanic lithosphere tectonically emplaced in continental settings. They are diagnostic features of continental suture zones, where they mark past plate boundaries. Even after having been studied for more than 40 years, the mechanisms involved in the genesis and subsequent obduction of ophiolites over continental margins are still debated. We present the results of 2D thermal-mechanical numerical models that successfully reproduce characteristics of natural examples like the Semail, Bay of Islands, Yarlung-Zangbo, and Coast Range ophiolites. The numerical models are upper mantle scale and use pressure-, temperature- and strain-dependent viscous-plastic rheologies. Both divergent and convergent velocity boundary conditions are used and tectonic boundary forces are monitored. The models start with the rifting of a stable continent, followed by development of an ocean ridge and accretion of oceanic lithosphere at a total rate of 3 cm/y. Once a specified ocean size/age is achieved, the velocity boundary conditions are reversed leading to convergence and the spontaneous inception of a suduction zone at the mid-ocean ridge. We present results for models including different ages of oceans (40 to 90 Ma) and different convergence velocities (5 to 15 cm/y). The interaction between the lower plate passive margin and the oceanic upper plate results in 5 different tectonic styles. These differ mainly by the presence or absence of oceanic spreading in the upper plate (back-arc basin), leading to supra-subduction zone ophiolites vs. MORB-type, and by the behaviour of the oceanic slab, e.g., slab rollback vs. breakoff. The evolution of effective slab pull is interpreted to be the major control on the resulting tectonic style. Low effective slab pull models (young oceans and fast convergence rates) fail to obduct an ophiolite. Strong effective slab pull models (old oceans and lower convergence rates) result in subduction zone retreat and spontaneous oceanic

  19. Petrologic evolution of the Caetano magmatic system: What can we learn from a dissected, 34 Ma caldera in the northern Great Basin, western U.S.A.?

    NASA Astrophysics Data System (ADS)

    Watts, K. E.; Colgan, J. P.; John, D. A.; Henry, C. D.

    2012-12-01

    depths of ~14-15 km. In light of our new petrologic data, we highlight the following key points: (1) Diverse crystal cargoes, disequilibrium textures, and wide compositional oscillations in single phenocrysts and among discrete mineral populations indicate prolonged and complex episodes of magma assembly and growth. Based on zircon U-Pb SHRIMP ages that range from ~34-37 Ma, assembly and growth may have spanned ~2-3 Ma, or a 34 Ma Caetano magma chamber may have assimilated older igneous rocks in and around the caldera. (2) Mineral chemistry, U-Pb and Ar-Ar geochronology, O isotope geochemistry, and whole rock major and trace element geochemistry indicate a genetic connection between the Caetano Tuff and resurgent granitic plutons, supporting the role of linked volcanic-plutonic components in caldera settings. (3) Generation and eruption of crystal-rich "monotonous" rhyolite calls into question the prevailing paradigms of crystal-poor rhyolites derived from crystal mushes, or crystal-rich "monotonous intermediates" derived from homogeneous dacitic magma reservoirs. The Caetano Tuff may be a representative end member of caldera-forming eruptions that is important for understanding large-volume rhyolite genesis in the shallow-middle crust.

  20. Petrology and geochemistry of Antarctic micrometeorites

    NASA Astrophysics Data System (ADS)

    Kurat, Gero; Koeberl, Christian; Presper, Thomas; Brandstätter, Franz; Maurette, Michel

    1994-09-01

    The petrology and geochemistry of twentythree chondritic dust particles with masses of 1-47 μg (sizes 100-400 μm) were recovered from blue ice near Cap Prudhomme, Antarctica, and studied by INAA, ASEM, EMPA, and optical microscopy. Sample selection criteria were irregular shape and (for a subsample) black color, with the aim of studying as many unmelted micrometeorites (MMs) as possible. Of thirteen unmelted MMs, six were phyllosilicate-dominated MMs, and seven were coarsegrained crystalline MMs consisting mainly of olivine and pyroxene. The remaining ten particles were largely melted and consisted of a foamy melt with variable amounts of relic phases (scoriaceous MMs). Thus, of the black particles selected, an astonishing portion, 40% (by number), consisted of largely unmelted MMs. Although unmelted, most phyllosilicate MMs have been thermally metamorphosed to a degree that most of the phyllosilicates were destroyed, but not melted. The original preterrestrial mineralogy is occasionally preserved and consists of serpentine-like phyllosilicates with variable amounts of cronstedtite, tochilinite-like oxides, olivine, and pyroxene. The crystalline MMs consist of olivine, low-Ca pyroxene, tochilinite-like oxides, and occasional Ni-poor metal. Relics in scoriaceous MMs consist of the same phases. Mineral compositions and the coexistence of phyllosilicates with anhydrous phases are typical of CM and CR-type carbonaceous chondrites. However, the olivine/pyroxene ratio (~ 1) and the lack of carbonates, sulfates, and of very Fe-poor, refractory element-rich olivines and pyroxenes sets the MMs apart from CM and CR chondrites. The bulk chemistry of the phyllosilicate MMs is similar to that of CM chondrites. However, several elements are either depleted (Ca, Ni, S, less commonly Na, Mg, and Mn) or enriched (K, Fe, As, Br, Rb, Sb, and Au) in MMs as compared to CM chondrites. Similar depletions and enrichments are also found in the scoriaceous MMs. We suggest that the

  1. Research on genesis of pyrite near the Permian-Triassic boundary in meishan, Zhejiang, China

    USGS Publications Warehouse

    Jiang, Y.-F.; Tang, Y.-G.; Chou, C.-L.

    2006-01-01

    The content and crystal forms of pyrite and sulfur isotope composition of pyrite sulfur as well as its vertical distribution near the Permian-Triassic (P/T) boundary in the Meishan section, Changxing county, Zhejiang province, China were studied using geological, petrological, mineralogical and geochemical methods (techniques). The result showed that the genesis of abundant pyrites in bed 24e2 at the uppermost part of the Changxing Formation in the Meishan section may be related to volcanic activity. In bed 24e2 of the Meishan section, pyrite has its highest content of 1.84% and the sulfur isotope composition has the highest ??34S value at + 2.2??? which is very similar to that of the average value of volcanic gas. There are some volcanic products such as ??-quartz, siliceous cylinders and siliceous spherules which coexisted with pyrites in beds 24e2 and 24f. It can be concluded that a large quantity of volcanic ash fell into the South China Sea and was incorporated into marine sediments during the formation of limestone at the uppermost part of the Changxing Formation. The volcanic eruption with massive amounts of H2S and S02 gas at the end of the Permian period resulted in the enrichment of H2S in the South China Sea areas. The reaction of H2S with reactive iron minerals formed the mass of abundant pyrites.

  2. Geophysical, petrological and mineral physics constraints on Earth's surface topography

    NASA Astrophysics Data System (ADS)

    Guerri, Mattia; Cammarano, Fabio; Tackley, Paul J.

    2015-04-01

    modeled topography. We also test several viscosity models, either radially symmetric, the V1 profile from Mitrovica and Forte [2004], or more complex laterally varying structures. All the property fields are expanded in spherical harmonics, until degree 24, and implemented in the code StagYY [Tackley, 2008] to perform mantle instantaneous flow modeling and compute surface topography and gravitational field. Our results show the importance of constraining the crustal and mantle density structure relying on a multidisciplinary approach that involves experimentally robust thermodynamic datasets. Crustal density field has a strong effect on the isostatic component of topography. The models that we test, CRUST 1.0 and those in Guerri and Cammarano [2015], produce strong differences in the computed isostatic topography, in the range ±600 m. For the lithospheric mantle, relying on experimentally robust material properties constraints is necessary to infer a reliable density model that takes into account chemical heterogeneities. This approach is also fundamental to correctly interpret seismic models in temperature, a crucial parameter, necessary to determine the lithosphere-asthenosphere boundary, where static effects on topography leave place to dynamic ones. The comparison between results obtained with different viscosity fields, either radially symmetric or vertically and laterally varying, shows how lateral viscosity variations affect the results, in particular the modeled geoid, at different wavelengths. References: Brocher, T. M. (2005), Empirical Relations between Elastic Wavespeeds and Density in the Earth's Crust, Bulletin of the Seismological Society of America, 95(6), 2081-2092. Cammarano, F., P. J. Tackley, and L. Boschi (2011), Seismic, petrological and geodynamical constraints on thermal and compositional structure of the upper mantle: global thermochemical models, Geophys. J. Int. Connolly, J. A. D. (2005), Computation of phase equilibria by linear programming: A

  3. Review and update of the applications of organic petrology: Part 1, geological applications

    USGS Publications Warehouse

    Suárez-Ruiz, Isabel; Flores, Deolinda; Mendonça Filho, João Graciano; Hackley, Paul C.

    2012-01-01

    Organic petrology developed as coal petrology at the beginning of the 20th century dedicated mainly to the study of coals because of their utilization in industry. Coal petrology was then considered a branch of coal science. Later, with the development of specialized nomenclature, classification of coal components, and the standardization and improvement of analytical (microscopical) methods, this discipline expanded in interests and name, becoming organic petrology. Organic petrology carries a broader context, being as well a tool applied in the study of dispersed organic matter in sedimentary rocks due to its importance in exploration for fossil fuel resources. At present, organic petrology is a discipline widely recognized for its role in fundamental and applied research with respect to both coal utilization and in geosciences. Throughout the 20th century several important monographs have been published on the discipline of organic petrology, including “Stach's textbook of coal petrology” (1st edition 1935, 2nd 1975, 3rd 1982), updated as the more general “Organic petrology” by Taylor et al. (1998). More recently, the text “Applied coal petrology: the role of petrology in coal utilization” was published by Suárez-Ruiz and Crelling (2008). This review is the first in a two-part review series that describes and updates the role of organic petrology in geosciences. A second part complementing this one and focused on the applications of organic petrology to other scientific fields will follow.

  4. Genesis Solar Wind Samples: Update of Availability

    NASA Technical Reports Server (NTRS)

    Gonzalez, C. P.; Allums, K. K.; Allton, J. H.

    2015-01-01

    The Genesis mission collected solar wind atoms for 28 months with a variety of collectors. The array wafer collector availability is displayed in the online catalog. The purpose of this report is to update the community on availability of array wafer samples and to preview other collectors which are in the process of being added to the online catalog. A total of fifteen pure materials were selected based on engineering and science requirements. Most of the materials were semiconductor wafers which were mounted on the arrays.

  5. Genesis of the sphygmogram from the kinetocardiogram.

    PubMed

    Juznic, G

    1979-01-01

    The functional uniformity of the heart and vessels is studied. The idea of the genesis of the carotid sphygmogram from the kinetocardiogram (GS-KCG) was developed on the basis of the analysis of the KCG and carotid-sphygmographic (CSG) pattern obtained in 10 young healthy adults. Two of these examinees were additionally examined under the influence of a s.c. injection of adrenaline (A) and noradrenaline (NA). Two kinds of transducers for the displacement of the chest wall and of the carotid region were used (photoelectric and resonance receiver). They did not touch the skin and were placed in four positions on the thorax; three of them are routine auscultatory positions (ictus, ERB, aorta), one was the carotid artery pulse position. Amplitude and time intervals at rest and under the influence of catecholamines were determined and their interrelationship studied. The amplitudes are more variable than the intervals. The genesis of the waves was studied on the basis of the records in four positions. On this basis, a uniform hypothesis about the genesis of the KCG and CSG waves is derived. From this hypothesis and from the existence of a reflection wave starting at the aorta, the concept of the genesis of the sphygmogram from the kinetocardiogram was developed: the deformation starts at the aorta, is directed to the apex, is there reflected and propagated to the carotid artery. The validity of this concept of the GS-KCG is proved on the basis of experiments with adrenaline and noradrenaline. The quantitative data of peaks and waves from four positions show a stability of the KCG and CSG pattern despite the influence of catecholamines. A comparison is made between the apex cardiogram (ACG) and KCG and determinants of the characteristic pattern of chest movements are given. It was further concluded that the technique of measuring reflection wave velocity (=intracardiac velocity) and pulse wave velocity (=vascular, mixed) can be used as a test for individual reactivity of

  6. The genesis of vertisols with gilgai microtopography: A review

    NASA Astrophysics Data System (ADS)

    Khitrov, N. B.

    2016-05-01

    Different hypotheses about the genesis of gilgai microtopography and corresponding soil complexes with clayey swelling soils are considered in this review. Their diversity is stipulated by specificities of the objects themselves and by the history of studies of the composition, properties, regimes, and landscape conditions of the areas with Vertisols in different countries. Most of the hypotheses about the genesis of Vertisols with the gilgai microtopography suggest that strong swelling-shrinking processes take place in these soils in the course of moistening-drying cycles; the origin of shear stress in the soils, its spatial patterns, and the particular ways of translocation of the soil material are discussed. At the early stage of Vertisol studies, a hypothesis about the leading role of the process of "self-swallowing" of the soils as a result of filling of open cracks with the material from the upper soil horizons was popular. However, numerous facts suggest that the intensity of this process is relatively low, so that it cannot play the major role in the gilgai formation and cyclic changes in the thickness and properties of the soil horizons in Vertisols. Another important mechanism is the uneven moistening and drying of the whole soil volume resulting in the irregular distribution of inner tensions in the soil with the development of shear stress and plastic deformation of the soil mass. The hypotheses suggested in the recent decades are based on the models of soil mechanics. A number of hypotheses consider possible alternation and duration of evolutionary stages of the development of Vertisols with the gilgai microtopography.

  7. Mineralogy and Petrology of New Antarctic Nakhlite MIL 03346

    NASA Technical Reports Server (NTRS)

    McKay, G.; Schwandt, C.

    2005-01-01

    Among the approx.1300 meteorites returned from Antarctica by the 2003-2004 ANSMET expedition was a 715g nakhlite, MIL 03346, recovered from the Miller Range. Samples of this meteorite were distributed to investigators on December 16, 2004. We were allocated PTS MIL 03346,63,100. This abstract is our preliminary report on the mineralogy and petrology of this important new sample.

  8. The Mineralogy and Petrology of Anomalous Eucrite Emmaville

    NASA Technical Reports Server (NTRS)

    Barrett, T. J.; Mittlefehldt, D. W.; Ross, D. K.; Greenwood, R. C.; Anand, M.; Franchi, I. A.; Grady, M. M.; Charlier, B. L. A.

    2015-01-01

    It has long been known that certain basaltic achondrites share similarities with eucrites. These eucrite-like achondrites have distinct isotopic compositions and petrologic characteristics indicative of formation on a separate parent body from the howardite-eucrite-diogenite (HED) clan (e.g., Ibitira, Northwest Africa (NWA) 011). Others show smaller isotopic variations but are otherwise petrologically and compositionally indistinguishable from basaltic eucrites (e.g., Pasamonte, Pecora Escarpment (PCA) 91007). The Emmaville eucrite has a delta O-17 value of -0.137 plus or minus 0.024 per mille (1 sigma), which is substantially different from the eucrite mean of -0.246 plus or minus 0.014 per mille (2 sigma), but similar to those of A-881394 and Bunburra Rockhole (BR). Currently little data exist for Emmaville in terms of petrology or bulk composition. Studying anomalous eucrites allows us to more completely understand the numbers of asteroids represented by eucrite- like basalts and thus constrain the heterogeneity of the HED suite. In this study, we present our preliminary petrological and mineral composition results for Emmaville.

  9. A Simulated Research Problem for Undergraduate Metamorphic Petrology.

    ERIC Educational Resources Information Center

    Amenta, Roddy V.

    1984-01-01

    Presents a laboratory problem in metamorphic petrology designed to simulate a research experience. The problem deals with data on scales ranging from a geologic map to hand specimens to thin sections. Student analysis includes identifying metamorphic index minerals, locating their isograds on the map, and determining the folding sequence. (BC)

  10. New insights on the petrology of submarine volcanics from the Western Pontine Archipelago (Tyrrhenian Sea, Italy)

    NASA Astrophysics Data System (ADS)

    Conte, A. M.; Perinelli, C.; Bianchini, G.; Natali, C.; Martorelli, E.; Chiocci, F. L.

    2016-11-01

    The Pontine Islands form a volcanic archipelago in the Tyrrhenian Sea. It consists of two edifices, the islands of Ponza, Palmarola and Zannone and the islands of Ventotene and Santo Stefano, respectively. The Archipelago developed during two main volcanic cycles in the Plio-Pleistocene: 1) the Pliocene episode erupted subalkaline, silica-rich volcanic units, which constitute the dominant products in the western edifice (Ponza and Zannone Islands); 2) the Pleistocene episode erupted more alkaline products, represented by evolved rocks (trachytes to peralkaline rhyolites) in the islands of Ponza and Palmarola and by basic to intermediate rocks in the eastern edifice (Ventotene and Santo Stefano Islands). In this paper we present new geochemical and petrological data from submarine rock samples collected in two oceanographic cruises and a scuba diving survey. The main result is the recovery of relatively undifferentiated lithotypes that provide further insights on the magmatic spectrum existing in the Pontine Archipelago, allowing modelling of the whole suite of rocks by fractional crystallization processes. New major and trace element data and thermodynamic constrains (by the software PELE) indicate the existence of three distinct evolutionary trends corresponding to a HK calcalkaline series in the Pliocene, followed by a transitional and then by a shoshonite series in the Pleistocene. In particular, the transitional series, so far overlooked in the literature, is required in order to explain the genesis of several peralkaline felsic rocks recognized in the Archipelago. On the whole, the new geochemical data i) confirm the orogenic signature of the suites, ii) allow to rule out an anatectic origin for both subalkaline and peralkaline rhyolites and iii) indicate highly heterogeneous mantle sources, due to crustal components variously recycled in the mantle via subduction.

  11. ORE's GENeric Evaluation SYStem: GENESYS 1988-89.

    ERIC Educational Resources Information Center

    Baenen, Nancy; And Others

    GENESYS--GENeric Evaluation SYStem--is a method of streamlining data collection and evaluation through the use of computer technology. GENESYS has allowed the Office of Research and Evaluation (ORE) of the Austin (Texas) Independent School District to evaluate a multitude of contrasting programs with limited resources. By standardizing methods and…

  12. Genesis Eco Systems, Inc. soil washing process

    SciTech Connect

    Cena, R.J.

    1994-10-11

    The Genesis soil washing system is an integrated system of modular design allowing for maximum material handling capabilities, with optimized use of space for site mobility. The Surfactant Activated Bio-enhanced Remediation Equipment-Generation 1 (SABRE-1, Patent Applied For) modification was developed specifically for removing petroleum byproducts from contaminated soils. Scientifically formulated surfactants, introduced by high pressure spray nozzles, displace the contaminant from the surface of the soil particles into the process solution. Once the contaminant is dispersed into the liquid fraction of the process, it is either mechanically removed, chemically oxidized, or biologically oxidized. The contaminated process water is pumped through the Genesis Biosep (Patent Applied For) filtration system where the fines portion is flocculated, and the contaminant-rich liquid portion is combined with an activated mixture of nutrients and carefully selected bacteria to decompose the hydrocarbon fraction. The treated soil and dewatered fines are transferred to a bermed stockpile where bioremediation continues during drying. The process water is reclaimed, filtered, and recycled within the system.

  13. Genesis Ultrapure Water Megasonic Wafer Spin Cleaner

    NASA Technical Reports Server (NTRS)

    Allton, Judith H.; Stansbery, Eileen K.; Calaway, Michael J.; Rodriquez, Melissa C.

    2013-01-01

    A device removes, with high precision, the majority of surface particle contamination greater than 1-micron-diameter in size from ultrapure semiconductor wafer materials containing implanted solar wind samples returned by NASA's Genesis mission. This cleaning device uses a 1.5-liter/minute flowing stream of heated ultrapure water (UPW) with 1- MHz oscillating megasonic pulse energy focused at 3 to 5 mm away from the wafer surface spinning at 1,000 to 10,000 RPM, depending on sample size. The surface particle contamination is removed by three processes: flowing UPW, megasonic cavitations, and centripetal force from the spinning wafer. The device can also dry the wafer fragment after UPW/megasonic cleaning by continuing to spin the wafer in the cleaning chamber, which is purged with flowing ultrapure nitrogen gas at 65 psi (.448 kPa). The cleaner also uses three types of vacuum chucks that can accommodate all Genesis-flown array fragments in any dimensional shape between 3 and 100 mm in diameter. A sample vacuum chuck, and the manufactured UPW/megasonic nozzle holder, replace the human deficiencies by maintaining a consistent distance between the nozzle and wafer surface as well as allowing for longer cleaning time. The 3- to 5-mm critical distance is important for the ability to remove particles by megasonic cavitations. The increased UPW sonication time and exposure to heated UPW improve the removal of 1- to 5-micron-sized particles.

  14. The genesis of collective health in Brazil.

    PubMed

    Vieira-da-Silva, Ligia Maria; Pinell, Patrice

    2014-03-01

    During the 1970s in Brazil a social space directed towards health problems on the population level, called collective health, was created and institutionalised. To what extent did this Brazilian invention correspond to a specific socio-historical practice? The works published on this topic have considered social medicine as a homogeneous phenomenon without empirically studying the specificities of national experiences. To bridge this gap, a historical study on the genesis of collective health in Brazil was carried out based on Bourdieu's field theory. The interaction between the paths of the founders and the conditions of historical possibilities were researched through documentary and bibliographical sources, as well as through in-depth interviews of the founders. This social space originated from a meeting of agents with different social backgrounds but who interconnected, creating a structure that was independent of each agent considered individually. One of the components of this establishment was the joining of theoretical production and the implementation of health reforms that resulted in the organisation of a universal health system. This study attempts to show how the international political situation and the contradictions of the national crisis created a universe of possibilities, allowing for the genesis of this sui generis space in Brazil.

  15. ACTION: application and extension of the GENESIS community analysis model.

    PubMed

    Russell, C K; Gregory, D M; Wotton, D; Mordoch, E; Counts, M M

    1996-06-01

    GENESIS (General Ethnographic and Nursing Evaluation Studies In the State) is a tested and proven community analysis strategy that integrates ethnographic and epidemiologic data to arrive at a comprehensive, holistic description of the health of a community and its residents. Communities analyzed in most project GENESIS studies have been rural or semirural. ACTION (Assessing Communities Together in the Identification Of Needs) is an extension of the GENESIS community analysis model that was developed to meet the unique needs of community-level research and analysis in an urban, multicultural setting. Significant differences in the context in which the ACTION projects took place necessitated extensions in specific components of the GENESIS model. Application of the GENESIS model by the ACTION team is described. Based on the experiences with ACTION, recommendations are offered for future urban, multicultural community analysis projects.

  16. A petrological view of early Earth geodynamics

    NASA Astrophysics Data System (ADS)

    Herzberg, C.

    2003-04-01

    Xenoliths of low T Archean cratonic mantle consist mostly of harzburgite and lherzolite with geochemical depletions that are characterisitc of igneous residues. Many authors have identified the complementary magmas as komatiites. This model is re-examined in light of work presented in Herzberg & O'Hara (2002) and found to be problematic. Munro-type alumina-undepleted komatiites from Alexo, Pyke Hill, and other locations often contain olivine phenocrysts with maximum Mg# \\cong 94. Residues of fractional melting would consist of pure dunite having Mg# = 97-98, but these are not observed. Residues of equilibrium melting would also be pure dunite with Mg# = 94, but these are also not observed. Olivines with Mg# = 94 are found in rare harzburgites, indicating that residues of alumina-undepleted komatiite have either been overprinted by subsequent magmatism or they have been geodynamically eroded. Alumina-undepleted komatiites can be successfully modeled with a primary magma containing 30% MgO produced by 0.5 mass fractions of equilibrium melting of depleted peridotite. A hot plume interpretation is consistent with both the petrology and helium isotopic compositions of alumina-undepleted komatiites. But what about cratonic mantle? The FeO and MgO contents of residues of fertile mantle peridotite formed by both equilibrium and fractional melting can be predicted and applied to xenoliths of cratonic mantle in most cases. Application to xenoliths from the Kaapvaal and Slave cratons is not possible owing to a second stage of Opx enrichment, but results can be applied to most xenoliths from Siberia, Tanzania, Somerset Island, and east Greenland as they contain less than 45% SiO_2. These xenoliths are very similar to residues produced by fractional melting. Pressures of initial melting were mostly 3 to 5 GPa, but can be as high 7 GPa. Pressures of final melting were highly variable and can be as low as 1 GPa. Potential temperatures (T_P) were typically 1450 to 1600oC and

  17. Satisfaction assessment with malleable prosthetic implant of Spectra (AMS) and Genesis (Coloplast) models.

    PubMed

    Casabé, A R; Sarotto, N; Gutierrez, C; Bechara, A J

    2016-11-01

    The malleable prosthetic implant is widely accepted among patients and physicians owing to a lower degree of surgical complexity, its rare mechanic failures and lower cost. We have compared the degree of satisfaction with malleable prosthetic implant in 60 patients, 36 with Spectra (AMS) and 24 with Genesis (Coloplast). For assessment purposes, we implemented the Erectile Dysfunction Inventory of Treatment Satisfaction (EDITS) satisfaction questionnaire adapted for penile prosthetic implants. The mean age and follow-up was 61.7 years (31-82) and 19.9 months (1-61), respectively. Mean EDITS scores did not indicate superiority of one implant over the other, overall satisfaction index being 77.1% and 75.6% for Genesis and Spectra prosthesis, respectively (P=0.4970). Our results revealed that these two models of malleable prostheses present a high level of satisfaction and confirm that the malleable prosthetic implant is an excellent option to treat patients with ED refractory to medical treatment.

  18. Genesis Solar Wind Array Collector Cataloging Status

    NASA Technical Reports Server (NTRS)

    Burkett, P.J.; Rodriguez, M.C.; Calaway, M.C.; Allton, J.H.

    2009-01-01

    Genesis solar wind array collectors were fractured upon landing hard in Utah in 2004. The fragments were retrieved from the damaged canister, imaged, repackaged and shipped to the Johnson Space Center curatorial facility [1]. As of January 2009, the collection consists of 3460 samples. Of these, 442 are comprised into "multiple" sample groupings, either affixed to adhesive paper (177) or collected in jars (17), culture trays (87), or sets of polystyrene vials (161). A focused characterization task was initiated in May 2008 to document the largest samples in the collection. The task consisted of two goals: to document sapphire based fragments greater than 2 cm in one dimension, and to document silicon based fragments greater than 1 cm in one direction.

  19. Genesis: Removing Contamination from Sample Collectors

    NASA Technical Reports Server (NTRS)

    Lauer, H. V.; McNamara, K. M.; Westphal, Andrew; Butterworth, A. L.; Burnett, D. S.; Jurewicz, A.; Woolum, D.; Allton, J. H.

    2005-01-01

    The Genesis mission returned to Earth on September 8, 2004, experiencing a non-nominal reentry. The parachutes which were supposed to slow and stabilize the capsule throughout the return failed to deploy, causing the capsule to impact the desert floor at a speed of nearly 200 MPH. Both the science canister and the major components of the SRC were returned before nightfall on September 8 to the prestaged cleanroom at UTTR , avoiding prolonged exposure or pending weather changes which might further contaminate the samples. The majority of the contaminants introduced as a result of the anomalous landing were in the form of particulates, including UTTR dust and soil, carbon-carbon heat shield material, and shattered collector dust (primarily silicon and germanium). Additional information is included in the original extended abstract.

  20. Status of Genesis Mo-Pt Foils

    NASA Technical Reports Server (NTRS)

    Nishiizumi, K.; Allton, J. H.; Burnett, D. S.; Butterworth, A. L.; Caffee, M. W.; Clark, B.; Jurewicz, A. J. G.; Komura, K.; Westphal, A. J.; Welten, K. C.

    2005-01-01

    A total of 8,000 sq cm of Mo-coated Pt foils were exposed to solar wind for 884 days by the Genesis mission. Solar wind ions were captured in the surface of the Mo. Our objective is the measurement of long-lived radionuclides, such as Be-10, Al-26, Cl-36, and Mn-53, and short-lived radionuclides, such as Na-22 and Mn-54, in the captured sample of solar wind. The expected flux of these nuclides in the solar wind is 100 atom/sq cm yr or less. The hard landing of the SRC (Sample Return Capsule) at UTTR (Utah Test and Training Range) has resulted in contaminated and crumpled foils. Here we present a status report and revised plan for processing the foils.

  1. Genesis Science Team Report on Mission Status

    NASA Astrophysics Data System (ADS)

    Burnett, D. S.

    2005-12-01

    The Genesis Discovery Mission exposed pure materials to the solar wind at the L1 Lagrangian point for 27 months between December 2001 and April 2004. These were returned for analysis in terrestrial laboratories in Sept 2004. The general science objectives for Genesis are: (1) measure solar isotopic abundance ratios to the precision required for planetary science problems, (2) improve the accuracy of photospheric elemental abundances by a least a factor of three, (3) provide independent analyses of the 3 major solar wind regimes and (4) provide a reservoir of solar matter for subsequent studies. Based on these general objectives, we are working towards a list of 18 specific prioritized measurement objectives, the first 5 of which are isotopic measurements. The two highest priority objectives are the isotopic compositions of O and N; to obtain a higher signal to background ratio for these elements, a concentrator (focusing ion telescope) was built at LANL to provide a factor of 20 fluence enhancement for elements lighter than P on a 30 mm radius target. The concentrator performed well in flight. A variety of other collector materials, tailored to specific analytical approaches, were mounted in 5 arrays of 55 hexagons, 4 cm point to point. Three of the arrays were used to provide the independent regime (coronal hole, low speed interstream, and coronal mass ejection) samples. The solar wind regime was measured by LANL Solar Wind Monitors on the Genesis spacecraft and the appropriate array exposed while the inappropriate array remained shielded. Array switchouts were carried out flawlessly during flight. Sample analyses have been slowed considerably by a parachute deployment failure which caused a crash of the sample return capsule upon reentry and by the presence of an in-flight contamination film, affectionately referred to as the brown stain. The crash has led to major loss of collector materials, along with significant pitting and scratching of the surviving

  2. The Genesis Solar Wind Sample Return Mission

    NASA Technical Reports Server (NTRS)

    Wiens, Roger C.; Burnett, Donald S.; Neugebauer, Marcia; Sasaki, Chester; Sevilla, Donald; Stansbery, Eileen; Clark, Ben; Smith, Nick; Oldham, Lloyd

    1990-01-01

    The Genesis spacecraft was launched on August 8 from Cape Canaveral on a journey to become the first spacecraft to return from interplanetary space. The fifth in NASA's line of low-cost Discovery-class missions, its goal is to collect samples of solar wind and return them to Earth for detailed isotopic and elemental analysis. The spacecraft is to collect solar wind for over two years, while circling the L1 point 1.5 million km sunward of the earth, before heading back for a capsule-style re-entry in September, 2004. After parachute deployment, a mid-air helicopter recovery will be used to avoid a hard landing. The mission has been in the planning stages for over ten years. Its cost, including development, mission operations, and sample analysis, is approximately $209M. The Genesis science team, headed by principal investigator Donald Burnett of Caltech, consists of approximately 20 co-investigators from universities and science centers around the country and internationally. The spacecraft consists of a relatively flat spacecraft bus containing most of the subsystem components, situated below a sample return capsule (SRC) which holds the solar-wind collection substrates and an electrostatic solar wind concentrator. Some of the collectors are exposed throughout the collection period, for a sample of bulk solar wind, while others are exposed only to certain solar wind regimes, or types of flow. Ion and electron spectrometers feed raw data to the spacecraft control and data-handling (C&DH) unit, which determines ion moments and electron flux geometries in real time. An algorithm is used to robotically decide between interstream (IS), coronal hole (CH), and coronal mass ejection (CME) regimes, and to control deployment of the proper arrays to sample these wind regimes independently. This is the first time such a solar-wind decision algorithm has been used on board a spacecraft.

  3. Temporal order of bipolar cell genesis in the neural retina

    PubMed Central

    Morrow, Eric M; Chen, C-M Amy; Cepko, Constance L

    2008-01-01

    Background Retinal bipolar cells comprise a diverse group of neurons. Cone bipolar cells and rod bipolar cells are so named for their connections with cone and rod photoreceptors, respectively. Morphological criteria have been established that distinguish nine types of cone bipolar cells and one type of rod bipolar cell in mouse and rat. While anatomical and physiological aspects of bipolar types have been actively studied, little is known about the sequence of events that leads to bipolar cell type specification and the potential relationship this process may have with synapse formation in the outer plexiform layer. In this study, we have examined the birth order of rod and cone bipolar cells in the developing mouse and rat in vivo. Results Using retroviral lineage analysis with the histochemical marker alkaline phosphatase, the percentage of cone and rod bipolar cells born on postnatal day 0 (P0), P4, and P6 were determined, based upon the well characterized morphology of these cells in the adult rat retina. In this in vivo experiment, we have demonstrated that cone bipolar genesis clearly precedes rod bipolar genesis. In addition, in the postnatal mouse retina, using a combination of tritiated-thymidine birthdating and immunohistochemistry to distinguish bipolar types, we have similarly found that cone bipolar genesis precedes rod bipolar genesis. The tritiated-thymidine birthdating studies also included quantification of the birth of all postnatally generated retinal cell types in the mouse. Conclusion Using two independent in vivo methodologies in rat and mouse retina, we have demonstrated that there are distinct waves of genesis of the two major bipolar cell types, with cone bipolar genesis preceding rod bipolar genesis. These waves of bipolar genesis correspond to the order of genesis of the presynaptic photoreceptor cell types. PMID:18215319

  4. Lunar and Planetary Science XXXV: Martian Meteorites: Petrology

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The session "Martian Meteorites: Petrology: included the following reports:Volatile Behavior in Lunar and Terrestrial Basalts During Shock: Implications for Martian Magmas; Problems with a Low-Pressure Tholeiitic Magmatic History for the Chassigny Dunite; Fast Cooling History of the Chassigny Martian Meteorite; Rehomogenized Interstitial and Inclusion Melts in Lherzolitic Shergottite ALH 77005: Petrologic Significance; Compositional Controls on the Formation of Kaersutite Amphibole in Shergottite Meteorites; Chemical Characteristics of an Olivine-Phyric Shergottite, Yamato 980459; Pb-Hf-Sr-Nd Isotopic Systematics and Age of Nakhlite NWA 998; Noble Gases in Two Samples of EETA 79001 (Lith. A); Experimental Constraints on the Iron Content of the Martian Mantle; and Mars as the Parent Body for the CI Carbonaceous Chondrites: New Data.

  5. GENESIS: GPS Environmental and Earth Science Information System

    NASA Technical Reports Server (NTRS)

    Hajj, George

    1999-01-01

    This presentation reviews the GPS ENvironmental and Earth Science Information System (GENESIS). The objectives of GENESIS are outlined (1) Data Archiving, searching and distribution for science data products derived from Space borne TurboRogue Space Receivers for GPS science and other ground based GPS receivers, (2) Data browsing using integrated visualization tools, (3) Interactive web/java-based data search and retrieval, (4) Data subscription service, (5) Data migration from existing GPS archived data, (6) On-line help and documentation, and (7) participation in the WP-ESIP federation. The presentation reviews the products and services of Genesis, and the technology behind the system.

  6. The petrology of the Apollo 12 pigeonite basalt suite

    NASA Technical Reports Server (NTRS)

    Baldridge, W. S.; Beaty, D. W.; Hill, S. M. R.; Albee, A. L.

    1979-01-01

    A study of the petrology of the Apollo 12 pigeonite basalt samples 12011, 12043, and 12007 is presented. In this suite, the abundances of olivine and Cr-spinel decrease with increasing grain size, while the abundances of plagioclase and ilmenite increase. The petrochemical and textural variations indicate that the pigeonite basalts were derived from the olivine basalts, but the compositional gap between the olivine and pigeonite basalts indicates that they could not have crystallized together from a single, initially homogeneous magma body.

  7. Petrology of impactites from Lake St. Martin structure, Manitoba

    NASA Technical Reports Server (NTRS)

    Simonds, C. H.; Mcgee, P. E.

    1979-01-01

    The 23-km Lake St. Martin crater was produced 200 to 250 million years ago in Archean granitic to amphibolic gneiss, overlain by 400 to 500 m of Ordovician to Devonian limestone and dolomite. In the present paper, a schematic model of the field geology, petrology, and geochemistry is presented. The scenario is built in part on the calculations of Kieffer and Simonds and observations made on the Lake St. Martin structure.

  8. Petrological evidence for secular cooling in mantle plumes.

    PubMed

    Herzberg, Claude; Gazel, Esteban

    2009-04-02

    Geological mapping and geochronological studies have shown much lower eruption rates for ocean island basalts (OIBs) in comparison with those of lavas from large igneous provinces (LIPs) such as oceanic plateaux and continental flood provinces. However, a quantitative petrological comparison has never been made between mantle source temperature and the extent of melting for OIB and LIP sources. Here we show that the MgO and FeO contents of Galapagos-related lavas and their primary magmas have decreased since the Cretaceous period. From petrological modelling, we infer that these changes reflect a cooling of the Galapagos mantle plume from a potential temperature of 1,560-1,620 degrees C in the Cretaceous to 1,500 degrees C at present. Iceland also exhibits secular cooling, in agreement with previous studies. Our work provides quantitative petrological evidence that, in general, mantle plumes for LIPs with Palaeocene-Permian ages were hotter and melted more extensively than plumes of more modern ocean islands. We interpret this to reflect episodic flow from lower-mantle domains that are lithologically and geochemically heterogeneous.

  9. Chemistry and petrology of Apollo 12 drive tube 12027

    NASA Technical Reports Server (NTRS)

    Smith, M. R.; Laul, J. C.; Simon, S. B.; Papike, J. J.

    1985-01-01

    Papike et al. (1982) have provided a summary of previous petrologic and chemical studies of the lunar regolith, taking into account samples from all of the Apollo and Luna sites. On the basis of these studies, an understanding is obtained of the processes which form and characterize the lunar regolith. It is found that comminution of local lithologies by meteorite impact and soil mixing are the most important regolith-forming processes. On the basis of grain size studies of Apollo 14 surface, trench, and drive tube soils, Simin et al. (1982) and Laul et al. (1982) concluded that comminution of local lithologies and vertical soil mixing processes are most important in the formation of the soils at that site. In the present investigation, this study of chemistry and petrology of lunar soils is extended to the Apollo 12 drive tube 12027. This drive tube provides an opportunity to study lunar soil from a depositional environment involving a location at the rim of a crater. The chemical and petrologic data are found to be consistent and suggest three stratigraphic units in the 12027 core.

  10. Petrology of Anomalous Mafic Achondrite Polymict Breccia Pasamonte

    NASA Technical Reports Server (NTRS)

    Mittlefehldt, D. W.; Berger, E. L.; Le, L.

    2017-01-01

    The most common asteroidal igneous meteorites are eucrite-type basalts and gabbros - rocks composed of ferroan pigeonite and augite, calcic plagioclase, silica, ilmenite, troilite, Ca-phosphate, chromite and Fe-metal [1]. These rocks are thought to have formed on a single asteroid, widely considered to be 4 Vesta, along with howardites and diogenites [1, 2]. High precision O-isotopic analyses have shown that some eucrites have small, well-resolved O-isotopic differences from the group mean [3-5]. These Oanomalous eucrites are thought to hail from asteroidal parents that are distinct from that of eucrites [5]. Three O-anomalous eucrites are PCA 82502, PCA 91007 (paired) and Pasamonte, all of which have the same O-isotopic composition [5, 6]. Our petrologic studies have shown that PCA 82502 and PCA 91007 have well-resolved anomalies in low-Ca pyroxene Fe/Mn compared to eucrites [6]. Divalent Mn and Fe are homologous species that do not greatly fractionate during igneous processes; mafic mineral Fe/Mn can be used to fingerprint parent object sources [7]. Previous petrological studies of Pasamonte [8-10] have not yielded sufficiently precise Fe/Mn ratios to allow distinction of anomalies of the scale of those found for the PCA basalts. We have begun petrological study of Pasamonte for comparison with our results on normal and anomalous eucrites [6], and to constrain its origin.

  11. Apollo 14 Lunar glass fragment known as Genesis bean

    NASA Technical Reports Server (NTRS)

    1972-01-01

    A tiny green glass fragment taken from an Apollo 14 core tube sampling. Because of its scientific significance and shape, the fragment has been nicknamed the 'Genesis bean'. The main constituents are iron and magnesium.

  12. Decontamination of Genesis Array Materials by UV Ozone Cleaning

    NASA Astrophysics Data System (ADS)

    Calaway, M. J.; Burnett, D. S.; Rodriguez, M. C.; Sestak, S.; Allton, J. H.; Stansbery, E. K.

    2007-03-01

    XPS and spectroscopic ellipsometry are used to evaluate the effectiveness of UV ozone cleaning for removing a carbon based surface contaminate on silicon and sapphire semiconductor materials from NASA's Genesis solar wind sample return mission.

  13. The genesis of craniofacial biology as a health science discipline.

    PubMed

    Sperber, G H; Sperber, S M

    2014-06-01

    The craniofacial complex encapsulates the brain and contains the organs for key functions of the body, including sight, hearing and balance, smell, taste, respiration and mastication. All these systems are intimately integrated within the head. The combination of these diverse systems into a new field was dictated by the dental profession's desire for a research branch of basic science devoted and attuned to its specific needs. The traditional subjects of genetics, embryology, anatomy, physiology, biochemistry, dental materials, odontology, molecular biology and palaeoanthropology pertaining to dentistry have been drawn together by many newly emerging technologies. These new technologies include gene sequencing, CAT scanning, MRI imaging, laser scanning, image analysis, ultrasonography, spectroscopy and visualosonics. A vibrant unitary discipline of investigation, craniofacial biology, has emerged that builds on the original concept of 'oral biology' that began in the 1960s. This paper reviews some of the developments that have led to the genesis of craniofacial biology as a fully-fledged health science discipline of significance in the advancement of clinical dental practice. Some of the key figures and milestones in craniofacial biology are identified.

  14. Developing ecospheres on transiently habitable planets: the genesis project

    NASA Astrophysics Data System (ADS)

    Gros, Claudius

    2016-10-01

    It is often presumed, that life evolves relatively fast on planets with clement conditions, at least in its basic forms, and that extended periods of habitability are subsequently needed for the evolution of higher life forms. Many planets are however expected to be only transiently habitable. On a large set of otherwise suitable planets life will therefore just not have the time to develop on its own to a complexity level as it did arise on earth with the cambrian explosion. The equivalent of a cambrian explosion may however have the chance to unfold on transiently habitable planets if it would be possible to fast forward evolution by 3-4 billion years (with respect to terrestrial timescales). We argue here, that this is indeed possible when seeding the candidate planet with the microbial lifeforms, bacteria and unicellular eukaryotes alike, characterizing earth before the cambrian explosion. An interstellar mission of this kind, denoted the `Genesis project', could be carried out by a relatively low-cost robotic microcraft equipped with a on-board gene laboratory for the in situ synthesis of the microbes.

  15. Magnetic Investigations in the J-M Reef Section of the Stillwater Complex, Montana

    NASA Astrophysics Data System (ADS)

    Wnukowski, J. D.; Ferre, E. C.; Butak, K. C.

    2014-12-01

    The Stillwater J-M reef, the only economic platinum deposit in the USA, consists of a 0.5 to 4 m-thick stratiform zone of platinum group element (PGE)-rich sulfides in a layered mafic intrusion. The origin of this reef, purely magmatic or related to late-stage magmatic fluids, remains ambiguous. I propose to test these two genetic hypotheses using rock magnetism. Fractional crystallization trends deduced from petrological models would produce a sharp increase in magnetite and pyrrhotite content near the solidus. In contrast, percolation of sulfur-rich fluids through a crystal mush would produce a gradual increase in magnetite and pyrrhotite up to a fluid permeability barrier. Continuous logging of the magnetic properties of drillcores, combined with petrographic observations, will allow to test these two models. Petrologic similarities between PGE reefs suggest that they share common physico-chemical origins, therefore, understanding the J-M reef genesis would have implications for other deposits such as the Bushveld Complex and the Great Dyke of Zimbabwe. The J-M reef formation has been explained by two alternative models: 1) magmatic model - magma replenishment causes thermal convection at the interface between two magmas, inducing PGE leaching by a sulfur-saturated magma, followed by precipitation of sulfide droplets; 2) fluid fluxing model - a sulfur-rich residual, late magmatic fluid migrates upward through the crystal mush leading to PGE concentration along a magmatic permeability barrier against the hanging wall. Both models account for the majority of geochemical and petrological observations and may not be fundamentally mutually exclusive. However, understanding the origin of PGE reefs would certainly benefit from new approaches. Preliminary data shows systematic inch-scale cycling variations of magnetic susceptibility (Km) in the hanging-wall that supports the magmatic model. The discovery of this magnetic cyclicity matters because this core does not

  16. Virtual petrological microscopy: web 2.0 technology for learning microscopy skills outside the laboratory

    NASA Astrophysics Data System (ADS)

    Kelley, S. P.; Whalley, P.; Tindle, A.

    2009-12-01

    Learning to use microscopes for geoscience or life science applications is a crucial part of the practical training offered in many science degrees, but the opportunities to study are often constrained by available laboratory space and time, and sometimes constrained by the number of high quality microscopes available. We will demonstrate a new based virtual petrological microscope which offers the opportunity for enhancement and enrichment of laboratory experience in geoscience. The focus of petrological microscope study is not primarily related to learning facts but is concerned with learning how to discriminate and classify within the paradigms of the discipline. In this case, the recognition and measurement of key features in rock samples in hand specimen and thin section. Whilst undertaking the practical exercise of recognition and naming of rock samples students are really being required to develop an understanding of the rock cycle as a model representing the relationship between rock categories and the process of their formation. The problems of teaching with complex visual materials, in effect of teaching learners 'how to see' from the scientific perspective of a particular discipline, are quite general. It could reasonably be expected that lessons learnt from the implementation and detailed evaluation of the proposed web-based system will generalise to many other topics in science education. Thus we focussed on the thin section images rather than reproducing a system that resembled a physical microscope. The virtual petrological microscope developed for a course at the Open University UK enables student acquisition of skills such as mineral and rock recognition using a browser window to explore thin sections of rocks as if they were using a laboratory microscope. The microscope allows students to pan around the thin sections (held as 1GB files on a remote server); zoom in and out, change from plane polarised light to cross polarised light conditions, and

  17. Compositional constraints on the genesis of diogenites

    NASA Astrophysics Data System (ADS)

    Mittlefehldt, David W.; Beck, Andrew W.; Lee, Cin-Ty A.; McSween, Harry Y.; Buchanan, Paul C.

    2012-01-01

    We have done bulk rock compositional analyses (INAA, ICP-MS) and petrologic study of a suite of diogenite meteorites. Most contain orthopyroxenes with mg#s of 70.6-79.0. Meteorite Hills (MET) 00425 is magnesian (mg# of 83.9). Lewis Cliff (LEW) 88011 contains orthopyroxene grains of varying mg# (76.3-68.6). Queen Alexandra Range (QUE) 93009 (orthopyroxene mg# 70.6) contains coarse-grained noritic clasts (plagioclase An84.7-88.3), and is rich in incompatible trace elements. It has Eu/Eu* < 1, indicating that cumulate norites do not dominate its trace element inventory. Queen Alexandra Range 93009 may be transitional between diogenites and magnesian cumulate eucrites. Lewis Cliff 88679, a dimict breccia of harzburgite and orthopyroxenite, has anomalously low concentrations of highly incompatible elements (e.g., Nb, La, Ta, U) compared to other diogenites, but is similar to them in less highly incompatible elements (e.g., Y, Zr, Yb, Hf). It is unlikely that this characteristic reflects a low proportion of a trapped melt component. The highly incompatible elements were likely mobilized after impact mixing of the two parent lithologies. Graves Nunataks 98108 shows an extreme range in Eu/Eu* attributable to the heterogeneous distribution of plagioclase; one sample has the lowest Eu/Eu* among diogenites. We find no compelling evidence to support the hypothesis that diogenite parent magmas were contaminated by partial melts of the eucritic crust. We posit that subsolidus equilibration between orthopyroxene and minor/trace phases (including phosphates) resulted in preferential redistribution of Eu2+ relative to Eu3+ and other rare earth elements, and results in anomalously low Eu/Eu* in samples leached in acids that dissolve phosphates.

  18. [Papillomavirus in the genesis of oral leukoplakia].

    PubMed

    Babichenko, I I; Rabinovich, O F; Ivina, A A; Rabinovich, I M; Togonidze, A A

    2014-01-01

    Immunohistochemical examination of the proliferative activity of cells was made investigating the expression of Ki-67 protein and the location of proteins associated with epithelial cell papillomavirus infection involving P16(INK4a) and HPV16 proteins in different cell areas of the intact mucosa, in leukoplakia with the signs of hyperplasia and dysplasia, and in squamous cell carcinoma. There was a positive correlation between the proliferative activity of cells in the parabasal cell areas and the expression of P16(INK4a) protein in oral leukoplakia with the signs of hyperplasia (r(s)=0.397; p=0.018). In oral leukoplakia with dysplastic changes, there was a positive correlation between the proliferation of cells in the parabasal and prickle cell layers and the location of HPV type 16 antigens (r(s)=0.515; p=0.041 and r(s)=0.651; p=0.006). Detection of papillomavirus infection in leukoplakia can solve not only the problems with its genesis, but this is also a morphological basis for the effective prevention and treatment of this common oral mucosal disease.

  19. Clostridium difficile infection: monoclonal or polyclonal genesis?

    PubMed

    Hell, M; Permoser, M; Chmelizek, G; Kern, J M; Maass, M; Huhulescu, S; Indra, A; Allerberger, F

    2011-10-01

    Clostridium difficile is considered to be a leading cause of hospital-acquired diarrhea. C. difficile (CDI) infection shows a high rate of recurrence. There would have to be a predominantly monoclonal mechanism of CDI within individual patients in order for molecular epidemiologic tools such as polymerase chain reaction (PCR) ribotyping to be useful in outbreak investigation or differentiation between infection relapse versus re-infection. It was the aim of our study to determine whether CDI is of monoclonal or of polyclonal genesis. Between December 2009 and June 2010, 11 patients with nosocomial CDI were chosen arbitrarily. Five individual colonies of C. difficile were picked from each of the primary culture plates. Of 55 isolates gained, 47 were available for PCR ribotyping (eight isolates failed attempts to re-culture). Among these 47 isolates, eight different PCR ribotypes were identified. Only one of the 11 patients had a stool sample that yielded more than one ribotype (PCR ribotypes 438 and 232); this 67-year-old female cancer patient was already suffering from recurring diarrhea prior to the fatal episode of colitis which was subsequently investigated. We conclude that polyclonal infections may occasionally occur in patients with CDI. Our findings of predominantly monoclonal origin of CDI within patients suggest that molecular epidemiologic investigations can be used reliably for outbreak investigations or discrimination between relapse and re-infection.

  20. On the genesis of the Haumea system

    NASA Astrophysics Data System (ADS)

    Campo Bagatin, A.; Benavidez, P. G.; Ortiz, J. L.; Gil-Hutton, R.

    2016-09-01

    The scenarios proposed in the literature for the genesis of the system formed by the dwarf planet 136108 Haumea, its two satellites and a group of some 10 bodies (the family) with semimajor axes, eccentricities and inclinations close to Haumea's values, are analysed against collisional, physical, dynamical and statistical arguments in order to assess their likelihood. All scenarios based on collisional events are reviewed under physical arguments and the corresponding formation probabilities in a collisional environment are evaluated according to the collisional evolution model ALICANDEP. An alternative mechanism is proposed based on the potential possibility of (quasi-) independent origin of the family with respect to Haumea and its satellites. As a general conclusion the formation of the Haumea system is a low-probability event in the currently assumed frame for the evolution of the outer Solar system. However, it is possible that current knowledge is missing some key element in the whole story that may contribute to increase the odds for the formation of such a system.

  1. Petrologic and oxygen isotopic study of ALH 85085-like chondrites

    NASA Astrophysics Data System (ADS)

    Prinz, M.; Weisberg, M. K.; Clayton, R. N.; Mayeda, T. K.; Ebihara, M.

    1994-07-01

    Four meteorites (PAT 91546, PCA 91328, PCA 91452, PCA 91467) petrologically similar to ALH 85085 chondrite have now been found. Previous studies of ALH 85085 showed it be a new kind of CR-related microchondrule-bearing chondrite, although one called it a sub-chondrite. The purpose of this study is to learn more about ALH 85085-like meteorites and their relationship to CR and CR-related (LEW 85332, Acfer 182, Bencubbin) chondrites. The methods used included petrology, INA bulk chemical analysis (PAT 91546, PCA 91467), and O isotopic analyses of the whole rocks and separated chondrules and dark inclusions (DIs) from PAT 91546. Since microchondrules and fragments are approximately 20 microns it was necessary to analyze composite samples for O; one was of approximately 100 chondrules, and another was of 5 DIs. Petrologically, the four meteorites are similar to ALH 85085, and there is no basis for determining if all of them, or any combinations, are paired. Mineralogically, olivine and pyroxene are highly magnesian FeNi metal generally has 3-10% Ni, and has a positive Ni-Co correlation similar to that in CR and CR-related chondrites. Refractory inclusions are similar in size to the chondrules and have the following assemblages: (1) hibonite-perovskite, (2) melilite-fassaite-forsterite, (3) grossite (Ca-dialuminate)-melilite-perovskite, (4) spinel-melilite, and (5) spinel-pyroxene aggregates. Chemically, INA analyses indicate that PAT 91546 and PCA 91467 are generally similar to ALH 85085. Oxygen isotopic analyses of the four whole-rock compositions fall along the CR mixing line as does ALH 85085; they are also close to LEW 85332, Acfer 182, and Bencubbin. This supports the concept that these are all CR-related chondrites. Even stronger support is found in the compositions of the chondrules and DIs in PAT 91546, which also plot on or near the CR line.

  2. Petrology and stratigraphy of Paleogene nonmarine sandstones, Cascade Range, Washington

    USGS Publications Warehouse

    Frizzell, Virgil A.

    1979-01-01

    The Cascade Range of Washington north of 47? latitude is composed of probable Paleozoic and Mesozoic metamorphic rocks and Mesozoic and Tertiary plutonic rocks. Several Paleogene nonmarine arkosic sandstone units fringe and in part occur within the complex crystalline core. The early to middle Eocene Chuckanut Formation is present on the west side of the crystalline core in the western foothills of the Cascades. The early to middle Eocene Swauk Formation partially encircles the Mt. Stuart massif of the central Cascades. In the western foothills of the Cascades, between the main body of Chuckanut Formation near Bellingham and the main outcrop area of the Swauk Formation south of Mt. Stuart, many smaller bodies of arkosic sandstone have variously been referred to either the Swauk or Chuckanut Formations. The early Eocene Manastash Formation occurs locally in an area south of the Yakima River. The middle to late Eocene Chumstick Formation is mostly confined to the Chiwaukum graben within the crystalline core and is separated from the Swauk Formation on the southwest by the Leavenworth Fault. The Oligocene Wenatchee Formation unconformably over lies the Chumstick Formation near Wenatchee. The middle to late Eocene Roslyn Formation crops out north of the Yakima River and is underlain by the Teanaway Basalt which separates the Roslyn from the older Swauk Formation. The middle Eocene to early Oligocene Naches Formation forms a north-trending body that crosses the Yakima River and is in fault contact with both the Swauk and Manastash Formations. The middle to late Eocene Puget Group underlies the Quaternary deposits of the Puget Lowland southeast of Seattle on the western flank of the Cascades. The various formations are all composed predominantly of fine- to medium-grained sandstones with lesser amounts of interbedded shale, conglomerate and coal. Compositionally, the units are predominantly either feldspathic or litho-feldspathic subquartzose sandstones. Volcanic rocks

  3. Mineralogic and petrologic studies of meteorites and lunar samples

    NASA Technical Reports Server (NTRS)

    Wood, J. A.

    1984-01-01

    During a 13 year period beginning in 1971, the Extraterrestrial Petrology Group examined lunar soils from all 6 Apollo missions and those returned by the Soviet Luna 16, Luna 20, and Luna 24 missions. In addition, the properties and apparent origin of the carbonaceous chondrites were examined. Chondrules, calcium-aluminum-rich inclusions (CAI) and the fine grained matrix materials that accompany chondrules and CAI's in primitive meteorites were investigated. The effects of planetary hydrothermal alteration of matrix materials in the C1 chondrite was also investigated. Full length papers and extended abstracts published during the grant are listed chronologically.

  4. Petrology and classification of the Garraf, Spain chondrite

    NASA Technical Reports Server (NTRS)

    Keil, K.; Conrad, G. H.; King, E. A.; San Miguel, A.

    1986-01-01

    Microscopic and electron microprobe studies indicate that the Garraf meteorite is a highly-recrystallized chondrite of petrologic type 6. Olivine (Fa24.7; PMD 1.1) and low-Ca pyroxene (Fs20.9; PMD 1.1) compositions indicate that it belongs to the L-group. Based on contents of noble gases, pervasive fracturing of silicates, common undulose extinction of olivine and plagioclase, and the lack of melt pockets and maskelynite, Garraf is placed into shock facies b. It is concluded that Garraf is a highly recrystallized L6b chondrite that, after recrystallization, was cataclased and comminuted by shock.

  5. Petrology of Two Itokawa Particles: Comparison with Equilibrated LL Chondrites

    NASA Technical Reports Server (NTRS)

    Komatsu, M.; Mikouchi, T.; Arai, T.; Fagan, T. J.; Zolensky, M.; Hagiya, K.; Ohsumi, K.; Karouji, Y.

    2015-01-01

    A strong link between Itokawa particles and LL chondrites was confirmed by preliminary examinations of Hayabusa particles [e.g., 1, 2]. Both poorly equilibrated and highly equilibrated particles have been found among the grains returned from Itokawa [1], and it is suggested that they correspond to LL4 and LL5-6, respectively. Here we report the petrography of two Itokawa particles and TEM study of one, and compare them to Antarctic LL chondrites with variable petrologic types (LL4-LL7) in order to understand the metamorphic history of asteroid Itokawa.

  6. Mineralogy and Petrology of COMET WILD2 Nucleus Samples

    NASA Technical Reports Server (NTRS)

    Zolensky, Michael; Bland, Phil; Bradley, John; Brearley, Adrian; Brennan, Sean; Bridges, John; Brownlee, Donald; Butterworth, Anna; Dai, Zurong; Ebel, Denton

    2006-01-01

    The sample return capsule of the Stardust spacecraft will be recovered in northern Utah on January 15, 2006, and under nominal conditions it will be delivered to the new Stardust Curation Laboratory at the Johnson Space Center two days later. Within the first week we plan to begin the harvesting of aerogel cells, and the comet nucleus samples they contain for detailed analysis. By the time of the LPSC meeting we will have been analyzing selected removed grains for more than one month. This presentation will present the first results from the mineralogical and petrological analyses that will have been performed.

  7. Petrogenesis of the Main Petrologic and Chronologic Volcanic Phases in the Gharyan Province, NW Libya.

    NASA Astrophysics Data System (ADS)

    Gafeer, A.; Nabelek, P. I.

    2014-12-01

    Cenozoic Libyan volcanic fields are manifestations of tremendous episodic outpourings of basaltic lavas within the East Saharan Craton. The volcanic fields are confined to a NW-SE trend (N140°E) that stretches from the Mediterranean coast in the north to Tibesti (Libya-Chad border) in the south. The four major volcanic fields (Gharyan, As-Sawda, Al-Haruj, and Nuquay) show a systematic decrease in age starting from ~55 Ma in Gharyan (NW) to the Holocene in Nuquay (SE). This apparent trend in ages along with characteristics resembling oceanic island basalts (OIB's) prompted several authors to attribute their origin to the African plate moving over a hot spot (e.g. Conticelli et al. 1995; Woller and Fediuk 1980; Hegazy 1999). In the Gharyan province (GVP), the igneous activity was indeed episodic and lasted for at least 50 Ma. The large span of ages of these volcanic rocks within the same volcanic field makes the hot spot model at least equivocal. Whole rock analyses for the major petrologic and chronologic units suggest that the basaltic and phonolitic suites within the GVP had different primary sources. The basaltic rocks show smooth REE patterns. LREE/HREE fractionations of the eruptive pulses are inconsistent with their ages, suggesting that they represent different melt fractions generated from the same mantle source. Phonolites show very different REE patterns. The patterns are concave-upward with low TbN/YbN ratios (0.6-0.8). The origin of the GVP basaltic rocks is consistent with melts generated from metasomatized lithospheric mantle across the garnet-spinel transition zone. The most primitive (>7 wt % MgO) basalts were used to model mantle melting processes and indicate 3-10% melting of an amphibole-bearing, spinel/garnet mantle source. Rather than being related to a hot spot, the genesis of the Libyan lavas appears to have been caused by reactivation of lithospheric megastructures with asthenospheric upwelling, in relation to the Africa-Europe convergence.

  8. Reheating and primordial gravitational waves in generalized Galilean genesis

    SciTech Connect

    Nishi, Sakine; Kobayashi, Tsutomu E-mail: tsutomu@rikkyo.ac.jp

    2016-04-01

    Galilean genesis is an alternative to inflation, in which the universe starts expanding from Minkowski with the stable violation of the null energy condition. In this paper, we discuss how the early universe is reheated through the gravitational particle production at the transition from the genesis phase to the subsequent phase where the kinetic energy of the scalar field is dominant. We then study the consequences of gravitational reheating after Galilean genesis on the spectrum of primordial gravitational waves. The resultant spectrum is strongly blue, and at high frequencies Ω{sub gw}∝ f{sup 3} in terms of the energy density per unit logarithmic frequency. Though this cannot be detected in existing detectors, the amplitude can be as large as Ω{sub gw}∼ 10{sup −12} at f∼ 100 MHz, providing a future test of the genesis scenario. The analysis is performed within the framework of generalized Galilean genesis based on the Horndeski theory, which enables us to derive generic formulas.

  9. Innovative genomic collaboration using the GENESIS (GEM.app) platform.

    PubMed

    Gonzalez, Michael; Falk, Marni J; Gai, Xiaowu; Postrel, Richard; Schüle, Rebecca; Zuchner, Stephan

    2015-10-01

    Next-generation sequencing has led to an unparalleled pace of Mendelian disease gene discovery in recent years. To address the challenges of analysis and sharing of large datasets, we had previously introduced the collaborative web-based GEM.app software [Gonzalez et al., ]. Here, we are presenting the results of using GEM.app over nearly 3 years and introducing the next generation of this platform. First, GEM.app has been renamed to GENESIS since it is now part of "The Genesis Project" (501c3), a not-for-profit foundation that is committed to providing the best technology to enable research scientists and to connecting patients and clinicians to genomic information. Second, GENESIS (GEM.app) has grown to nearly 600 registered users from 44 countries, who have collectively achieved 62 gene identifications or published studies that have expanded phenotype/genotype correlations. Our concept of user-driven data sharing and matchmaking is now the main cause for gene discoveries within GENESIS. In many of these findings, researchers from across the globe have been connected, which gave rise to the genetic evidence needed to successfully pinpoint-specific gene mutations that explained patients' disease. Here, we present an overview of the various novel insights that have been made possible through the data-sharing capabilities of GENESIS/GEM.app.

  10. Igneous and metamorphic petrology in the field: a problem-based, writing-intensive alternative to traditional classroom petrology

    NASA Astrophysics Data System (ADS)

    DeBari, S. M.

    2011-12-01

    The Geology Department at Western Washington University (~100 geology majors) offers field and classroom versions of its undergraduate petrology course. This is a one-quarter course (igneous and metamorphic petrology) with mineralogy as a prerequisite. The field version of the course is offered during the three weeks prior to fall quarter and the classroom version is offered in spring quarter. We take 15-20 students around the state of Washington, camping at different outcrop sites where students integrate observational skills, petrologic knowledge, and writing. Petrogenetic associations in various tectonic settings provide the theme of the course. We compare ophiolites vs. arc sequences (volcanic, plutonic, and metamorphic rocks), S- vs. I-type granitoids (plutonic rocks and associated metamorphic rocks), Barrovian vs. Buchan vs. subduction zone metamorphism of different protoliths, and flood-basalt vs. active-arc volcanism. Some basics are covered in the first day at WWU, followed by 17 days of field instruction. Lecture is integrated with outcrop study in the field. For example, students will listen to a lecture about magma differentiation processes as they examine cumulate rocks in the Mt. Stuart batholith, and a lecture about metamorphic facies as they study blueschist facies rocks in the San Juan Islands. Students study multiple outcrops around a site for 1-4 days. They then use their observations (sketches and written descriptions of mineral assemblages, rock types, rock textures, etc.) and analysis techniques (e.g. geochemical data plotting, metamorphic protolith analysis) to write papers in which the data are interpreted in terms of a larger tectonic problem. In advance of the writing process, students use group discussion techniques such as whiteboarding to share their observational evidence and explore interpretations. Student evaluations indicate that despite the intense pace of the course, they enjoy it more. Students also feel that they retain more

  11. Complexity.

    PubMed

    Gómez-Hernández, J Jaime

    2006-01-01

    It is difficult to define complexity in modeling. Complexity is often associated with uncertainty since modeling uncertainty is an intrinsically difficult task. However, modeling uncertainty does not require, necessarily, complex models, in the sense of a model requiring an unmanageable number of degrees of freedom to characterize the aquifer. The relationship between complexity, uncertainty, heterogeneity, and stochastic modeling is not simple. Aquifer models should be able to quantify the uncertainty of their predictions, which can be done using stochastic models that produce heterogeneous realizations of aquifer parameters. This is the type of complexity addressed in this article.

  12. Genesis of petroduric and petrocalcic horizons in Latinamerica volcanic soils

    NASA Astrophysics Data System (ADS)

    Quantin, Paul

    2010-05-01

    Introduction. In Latinamerica, from Mexico to Chile, there are indurated volcanic soils horizons, named 'tepetate' in Mexico or cangahua in the Andes Mountains. Apart from original volcanic tuffs, these horizons were produced by pedogenesis: either through a former weathering of volcanic ash layers into fragic and later to petrocalcic horizons; or after a former soil formation through a second process of transformation from clayey volcanic soils to silicified petroduric horizons. This oral presentation will briefly deal with the formation of petroduric horizons in Mexico and petrocalcic horizon in Ecuador. Petroduric horizon genesis in Mexico. A soil climato-toposequence, near to Veracruz (Rossignol & Quantin, 1997), shows downwards an evolution from a ferralic Nitisol to a petroduric Durisol. A Durisol profile comports these successive horizons: at the top A and Eg, then columnar Btg-sim, laminar Bt-sim , prismatic Bsim, plinthite Cg, over andesite lava flow. Among its main features are especially recorded: clay mineralogy, microscopy and HRTEM. These data show: an increase in cristobalite at the expenses of 0.7 nm halloysite in Egsiltans, laminar Bt-sim, around or inside the columns or prisms of Btg-sim and Bsimhorizons. HRTEM (Elsass & al 2000) on ultra thin sections reveals an 'epigenesis' of clay sheets by amorphous silica, to form successively A-opal, Ct-opal and microcrystalline cristobalite. From these data and some groundwater chemical analyses, a scenario of duripan formation from a past clayey Nitisol is inferred: clay eluviation-illuviation process? alternate redoximorphy? clay degradation, Al leaching and Si accumulation, to form successively A-opal, Ct-opal and cristobalite. Petrocalcic horizon genesis in Ecuador. A soil climato-toposequence on pyroclastic flows, near to Bolivar in Ecuador (Quantin & Zebrowski, 1997), shows downwards the evolution from fragic-eutric-vitric Cambisols to petrocalcic-vitric Phaeozems, at the piedmont under semi

  13. Investigation of Backside Textures for Genesis Solar Wind Silicon Collectors

    NASA Technical Reports Server (NTRS)

    Gonzalez, C. P.; Burkett, P. J.; Rodriguez, M. C.; Allton, J. H.

    2014-01-01

    Genesis solar wind collectors were comprised of a suite of 15 types of ultrapure materials. The single crystal, pure silicon collectors were fabricated by two methods: float zone (FZ) and Czochralski (CZ). Because of slight differences in bulk purity and surface cleanliness among the fabrication processes and the specific vendor, it is desirable to know which variety of silicon and identity of vendor, so that appropriate reference materials can be used. The Czochralski method results in a bulk composition with slightly higher oxygen, for example. The CZ silicon array wafers that were Genesis-flown were purchased from MEMC Electronics. Most of the Genesis-flown FZ silicon was purchased from Unisil and cleaned by MEMC, although a few FZ wafers were acquired from International Wafer Service (IWS).

  14. Cosmological matching conditions and galilean genesis in Horndeski's theory

    SciTech Connect

    Nishi, Sakine; Kobayashi, Tsutomu; Tanahashi, Norihiro; Yamaguchi, Masahide E-mail: tsutomu@rikkyo.ac.jp E-mail: gucci@phys.titech.ac.jp

    2014-03-01

    We derive the cosmological matching conditions for the homogeneous and isotropic background and for linear perturbations in Horndeski's most general second-order scalar-tensor theory. In general relativity, the matching is done in such a way that the extrinsic curvature is continuous across the transition hypersurface. This procedure is generalized so as to incorporate the mixing of scalar and gravity kinetic terms in the field equations of Horndeski's theory. Our matching conditions have a wide range of applications including the galilean genesis and the bounce scenarios, in which stable, null energy condition violating solutions play a central role. We demonstrate how our matching conditions are used in the galilean genesis scenario. In doing so, we extend the previous genesis models and provide a unified description of the theory admitting the solution that starts expanding from the Minkowski spacetime.

  15. Learning Mathematics in a CAS Environment: The Genesis of a Reflection about Instrumentation and the Dialectics between Technical and Conceptual Work.

    ERIC Educational Resources Information Center

    Artigue, Michele

    2002-01-01

    Presents an anthropological approach used in French research and the theory of instrumentation developed in cognitive ergonomics. Shows how these frameworks allow an approach to the educational use of CAS technology, focusing on the unexpected complexity of instrumental genesis, mathematical needs of instrumentation, status of instrumented…

  16. Using Image Pro Plus Software to Develop Particle Mapping on Genesis Solar Wind Collector Surfaces

    NASA Astrophysics Data System (ADS)

    Rodriguez, M. C.; Allton, J. H.; Burkett, P. J.

    2012-03-01

    The Genesis curatorial facility at JSC provides optical analysis of collector array surfaces as cleaning steps progress in an updated master cleaning plan coordinated by the Genesis mission PI Don Burnett.

  17. Genesis of a Comet (Artist's Concept)

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Quick Time Movie for PIA02106 Genesis of a Comet

    This artist's animation depicts one of the most widely accepted theories pertaining to the origin of comets.

    The simulation opens with a protoplanetary disk, which will eventually turn into a solar system. The fiery yellow ball in the center represents a star like our Sun.

    Like a raindrop forming in a cloud, a star forms in a diffuse gas cloud in deep space. As the star grows, its gravitational pull draws in dust and gas from the surrounding molecular cloud to form a swirling disk called a 'protoplanetary disk.' This disk eventually further consolidates to form planets, moons, asteroids and comets.

    As the animation zooms into the disk, micron-size particles of dust can be seen sticking together to form centimeter- and millimeter-sized rocks. As the rocks become more massive, gravity takes over, forcing other surrounding pebbles and dust particles to collide with the larger rocks. The process continues until a comet is born.

    Since comets form far from their star in the icy regions of the planetary system, molecules, such as water, carbon dioxide and methane, freeze onto the micron-sized dust particles and rocks before they collide to form a comet.

    Once a solar system is formed, the gravitational pull from large planets manipulates a comet's orbit and brings it into the inner solar system. As the comet approaches its star, sunlight warms and transforms the frozen gas on and just below the comet's surface directly into vapor, effectively bypassing the liquid phase. This process is called sublimation.

    Sublimation of the molecules beneath the surface forces streams of gas and dust to jet out of the comet, creating an aura or 'coma' around the rock. Interactions between ingredients in the coma with surrounding sunlight and solar winds eventually create the comet's tail, pictured here at the end of the animation.

    This movie is

  18. The Ezhimala Igneous Complex, southern India: Possible imprint of Late Cretaceous magmatism within rift setting associated with India-Madagascar separation

    NASA Astrophysics Data System (ADS)

    Mohan, M. Ram; Shaji, E.; Satyanarayanan, M.; Santosh, M.; Tsunogae, T.; Yang, Qiong-Yan; Dhanil Dev, S. G.

    2016-05-01

    The gabbro-granophyre-granite complex of Ezhimala emplaced along the western rifted continental margin of India preserves evidence for bimodal magmatism, with related magma mixing and mingling processes. Here we report petrological, geochemical, zircon U-Pb geochronological and Lu-Hf isotopic data from the Ezhimala Igneous Complex (EIC) that provide insights into the Late Cretaceous magmatic activity. Field investigations and petrographic observations in Zircon U-Pb data from the granophyres show emplacement ages of 93.21 ± 0.6 Ma and 94.26 ± 0.92 Ma. The evolved Lu-Hf isotopic systematics for these rocks are indicative of the involvement of older crustal material during magma genesis. The geochemical systematics together with isotopic data suggest magma generation in a rift-related setting, and interaction with or melting of Neoproterozoic basement rocks. The timing of magmatism broadly correlates with the Late Cretaceous Marion hotspot activity which is considered to be responsible for the break-up of India and Madagascar. We thus interpret the EIC to be one of the rare signatures in southern India for the final phase of rifting of Gondwana.

  19. The GENESIS Mission Solar Wind Samples: Collection Times, Estimated Fluences, and Solar-Wind Conditions

    NASA Astrophysics Data System (ADS)

    Reisenfeld, D. B.; Wiens, R. C.; Barraclough, B. L.; Steinberg, J. E.; Dekoning, C.; Zurbuchen, T. H.; Burnett, D. S.

    2005-03-01

    We have correlated the GENESIS sample collection times for the different solar-wind regimes with compositional data from GENESIS/GIM and ACE/SWICS instruments. We discuss GENESIS regime selection and new results in solar-wind elemental fractionation.

  20. Semantically Enabling Knowledge Representation of Metamorphic Petrology Data

    NASA Astrophysics Data System (ADS)

    West, P.; Fox, P. A.; Spear, F. S.; Adali, S.; Nguyen, C.; Hallett, B. W.; Horkley, L. K.

    2012-12-01

    More and more metamorphic petrology data is being collected around the world, and is now being organized together into different virtual data portals by means of virtual organizations. For example, there is the virtual data portal Petrological Database (PetDB, http://www.petdb.org) of the Ocean Floor that is organizing scientific information about geochemical data of ocean floor igneous and metamorphic rocks; and also The Metamorphic Petrology Database (MetPetDB, http://metpetdb.rpi.edu) that is being created by a global community of metamorphic petrologists in collaboration with software engineers and data managers at Rensselaer Polytechnic Institute. The current focus is to provide the ability for scientists and researchers to register their data and search the databases for information regarding sample collections. What we present here is the next step in evolution of the MetPetDB portal, utilizing semantically enabled features such as discovery, data casting, faceted search, knowledge representation, and linked data as well as organizing information about the community and collaboration within the virtual community itself. We take the information that is currently represented in a relational database and make it available through web services, SPARQL endpoints, semantic and triple-stores where inferencing is enabled. We will be leveraging research that has taken place in virtual observatories, such as the Virtual Solar Terrestrial Observatory (VSTO) and the Biological and Chemical Oceanography Data Management Office (BCO-DMO); vocabulary work done in various communities such as Observations and Measurements (ISO 19156), FOAF (Friend of a Friend), Bibo (Bibliography Ontology), and domain specific ontologies; enabling provenance traces of samples and subsamples using the different provenance ontologies; and providing the much needed linking of data from the various research organizations into a common, collaborative virtual observatory. In addition to better

  1. Organic petrology, thermal maturity, geology, and petroleum source rock potential of Lower Permian coal, Karoo supersystem, Zambia

    SciTech Connect

    Utting, J. ); Wielens, H. )

    1992-10-01

    This paper reports on data concerning organic petrology and thermal maturity of Lower Karoo coal measures (Lower Permian) which are of considerable importance in determining the hydrocarbon potential of sediments in the rift-valley and half-graben complexes of the Luangwa and Zambezi valleys of eastern and southern Zambia, respectively, and in the extensive sedimentary basin developed on relatively stable Precambrian basement in western Zambia, a total area in excess of 3000 km{sup 2}. Samples from seven outcrop and subsurface localities situated in the northeast (northern Luangwa Valley), east (mid-Luangwa Valley), south (mid-Zambezi Valley), and the Western Province of Zambia were studied. The coal measures are from 9 to 280 m thick, but individual coal seams are generally less than 6 m. The coal macerals contain an average of 60% vitrinite and 9% liptinite, enough to have potential to generate hydrocarbon. A few samples contain twice this amount of liptinite. Reflected-light microscopy and the thermal alteration index of spores were used to determine the thermal maturity. The organic matter in samples studied is within the oil generation zone (thermal alteration index 2{minus} to 2+; %R{sub 0} max = 0.5-0.9). The petrological and palynological data indicate that the organic matter consists of Types II (generally approximately 25% in carbonaceous shale samples), III, and IV, indicating source rock potential. Late Karoo ( ) and post-Karoo fault blocks with differential vertical displacements may have produced structural traps suitable for oil and gas accumulation.

  2. Lunar ferroan anorthosite 60025 - Petrology and chemistry of mafic lithologies

    NASA Technical Reports Server (NTRS)

    James, O. B.; Mcgee, J. J.; Lindstrom, M. M.

    1991-01-01

    Eleven splits from the mafic-mineral-rich part of anorthosite 60025 were studied in order to establish the exact nature and causes of compositional variations in the minerals of lunar ferroan anorthosites. All splits were analyzed by INAA, and five were studied intensively by petrologic techniques. All splits were found to have similar cataclastic textures and show textural evidence of at least two episodes of deformation. The whole-rock split contains mafic minerals having a wide range of compositions and is probably polymict. It is suggested that the rare-earth patterns for all splits can be duplicated safactorily, assuming that the equilibrium liquids had flat, or nearly flat, chondrite-normalized rare-earth patterns. The plagioclases in all splits were found to be identical. Data obtained indicate that in ferroan anorthosites An content in plagioclase and mg' of associated mafic minerals are not strongly correlated.

  3. APPLICATIONS OF CATHODOLUMINESCENCE OF QUARTZ AND FELDSPAR TO SEDIMENTARY PETROLOGY.

    USGS Publications Warehouse

    Ruppert, Leslie F.

    1987-01-01

    Cathodoluminescence (CL), the emission of visible light during electron bombardment, was first used in sandstone petrology in the mid-1960's. CL techniques are especially useful for determining the origin and source of quartz and feldspar, two of the most common constituents in clastic rocks. CL properties of both minerals are dependent on their temperature of crystallization, duration of cooling, and/or history of deformation. Detrital quartz and feldspar are typically derived from igneous and metamorphic sources and luminesce in the visible range whereas authigenic quartz and feldspar form at low temperatures and do not luminesce. Quantification of luminescent and non-luminescent quartz and feldspar with the scanning electron microscope, electron microprobe, or a commercial CL device can allow for the determination of origin, diagenesis, and source of clastic rocks when used in conjunction with field and other petrographic analyses.

  4. Petrology and geochemistry of alkali gabbronorites from lunar breccia 67975

    NASA Technical Reports Server (NTRS)

    James, Odette B.; Flohr, Marta K.; Lindstrom, Marilyn M.

    1987-01-01

    Detailed results of petrologic and compositional studies of three clasts found in thin sections of the Apollo 16 lunar breccia 67975 and of four clasts extracted from the breccia (for instrumental neutron activation analysis) prior to thin sectioning are reported. The alkali gabbronorites of the breccia form two distinct subgroups, magnesian and ferroan. The magnesian gabbronorites are composed of bytownitic plagioclase, hypersthene, augite, a silica mineral, and trace Ba-rich K-feldspar. The ferroan gabbronorites are composed of ternary plagioclase, pigeonite, augite, Ba-rich K-feldspar, and a silica mineral. Trace minerals in both subgroups are apatite, REE-rich whitlockite, and zircon. The magnesian and ferroan alkali gabbronorites appear to have formed by progressive differentiation of the same, or closely related, parent REE-rich magmas.

  5. Apollo 15 yellow impact glasses: Chemistry, petrology, and exotic origin

    SciTech Connect

    Delano, J.W.; Lindsley, D.H.; Ma, M.; Schmitt, R.A.

    1982-11-15

    The Apollo 15 yellow impact glasses are characterized by moderate TiO/sub 2/ (approx.4.8%) and high abundances of the large ion lithophile elements (e.g., K, P, Hf, Th, REE). Since the chemistry of these glasses cannot be duplicated by any combination of local components presently known to occur at the Apollo 15 landing site, these yellow glasses seem to be exotic to that area. Chemical and petrologic constraints suggest that these samples were produced by impact melting of an immature mare regolith developed upon an unusual variety of mare basalt. We speculate that the target basalt were the youngest lava flows known to exist on the moon (i.e., Eratosphenian-age lavas in Oceanus Procellarum and Mare Imbrium). Specific tests are proposed for evaluating this provocative hypothesis.

  6. Lunar basalt meteorite EET 87521: Petrology of the clast population

    NASA Technical Reports Server (NTRS)

    Semenova, A. S.; Nazarov, M. A.; Kononkova, N. N.

    1993-01-01

    The Elephant Moraine meteorite EET 87521 was classified as a lunar mare basalt breccia which is composed mainly of VLT basalt clasts. Here we report on our petrological study of lithic clasts and monomineralic fragments in the thin sections EET 87521,54 and EET 87521,47,1, which were prepared from the meteorite. The results of the study show that EET 87521 consists mainly of Al-rich ferrobasalt clasts and olivine pyroxenite clasts. The bulk composition of the meteorite can be well modelled by the mixing of these lithic components which appear to be differentiates of the Luna 25 basalt melt. KREEP and Mg-rich gabbro components are minor constituents of EET 87521.

  7. Petrology, chemistry, age and irradiation history of Luna 24 samples

    NASA Technical Reports Server (NTRS)

    Wasserburg, G. J.; Papanastassiou, D. A.; Mcculloch, M. T.; Huneke, J. C.; Dymek, R. F.; Depaolo, D. J.; Chodos, A. A.; Albee, A. L.; Radicati Di Brozolo, F.

    1978-01-01

    The results of petrological, chemical, isotopic age determination and irradiation studies of sample 24170 from the 170 cm depth of the regolith core returned from Mare Crisium by Luna 24 are presented. The sample is found to be comprised of fragments from a single igneous rock, with mineralogical evidence indicating it to be a mare basalt. The crystallization age is determined by Sm-Nd and Ar(40)-Ar(39) ages to be 3.30 AE, establishing the presence of relatively young flows. All soil samples show low trace element compositions with minimum contamination by KREEPUTh-rich materials. Rb-Sr and Sm-Nd relations reflect the absence of significant fractionation at ages younger than 4.5 AE. One soil sample shows extremely large neutron capture effects, imposing a new lower limit to the neutron production rate in the regolith and requiring the addition of irradiated materials from depth.

  8. Linking petrology and seismology at an active volcano.

    PubMed

    Saunders, Kate; Blundy, Jon; Dohmen, Ralf; Cashman, Kathy

    2012-05-25

    Many active volcanoes exhibit changes in seismicity, ground deformation, and gas emissions, which in some instances arise from magma movement in the crust before eruption. An enduring challenge in volcano monitoring is interpreting signs of unrest in terms of the causal subterranean magmatic processes. We examined over 300 zoned orthopyroxene crystals from the 1980-1986 eruption of Mount St. Helens that record pulsatory intrusions of new magma and volatiles into an existing larger reservoir before the eruption occurred. Diffusion chronometry applied to orthopyroxene crystal rims shows that episodes of magma intrusion correlate temporally with recorded seismicity, providing evidence that some seismic events are related to magma intrusion. These time scales are commensurate with monitoring signals at restless volcanoes, thus improving our ability to forecast volcanic eruptions by using petrology.

  9. Petrological Explanations for the Magnetic Anomalies Detected on Mars

    NASA Technical Reports Server (NTRS)

    Weitz, C. M.; Rutherford, M. J.

    1999-01-01

    The discovery of crustal magnetization 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 spreading process similar to that seen on Earth today. The larger magnetization of the martian crust compared to the Earth can be attributed to its higher Fe content and the proposed minerals associated with this magnetization 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 magnetic minerals in the martian rocks, thereby accounting for their intense magnetic properties.

  10. [Genesis of biorhythms of the cardiointervalogram in its evolutionary aspect].

    PubMed

    Lerner, E N; Bondarchuk, V I

    1985-09-01

    Statistical characteristics and latent biorhythms of the frog, rabbit and human cardiointervalograms were studied in the volutionary aspect with the aid of ACBT-M 6000 computer. Some mechanisms of temporary organization of the heart rhythm were revealed with regard to the level of organization of biological objects. Evolutionary aspects of analysis of the heart biorhythms provide an approach to their genesis.

  11. Genesis Solar Wind Collector Cleaning Assessment: 60366 Sample Case Study

    NASA Technical Reports Server (NTRS)

    Goreva, Y. S.; Gonzalez, C. P.; Kuhlman, K. R.; Burnett, D. S.; Woolum, D.; Jurewicz, A. J.; Allton, J. H.; Rodriguez, M. C.; Burkett, P. J.

    2014-01-01

    In order to recognize, localize, characterize and remove particle and thin film surface contamination, a small subset of Genesis mission collector fragments are being subjected to extensive study via various techniques [1-5]. Here we present preliminary results for sample 60336, a Czochralski silicon (Si-CZ) based wafer from the bulk array (B/C).

  12. Pristine Igneous Rocks and the Genesis of Early Planetary Crusts

    NASA Technical Reports Server (NTRS)

    Warren, Paul H.; Lindstrom, David (Technical Monitor)

    2002-01-01

    Our studies are highly interdisciplinary, but are focused on the processes and products of early planetary and asteroidal differentiation, especially the genesis of the ancient lunar crust. The compositional diversity that we explore is the residue of process diversity, which has strong relevance for comparative planetology.

  13. Small Particulate Contamination Survey Of Genesis Flight Sample 61423

    NASA Technical Reports Server (NTRS)

    Kuhlman, K. R.; Schmeling, M.; Gonzalez, C. P.; Allums, K. K.; Allton, J. H.; Burnett, D. S.

    2016-01-01

    The Genesis mission collected solar wind and brought it back to Earth in order to provide precise knowledge of solar isotopic and elemental compositions. The ions in the solar wind stop in the collectors at depths on the order of 10 to a few hundred nanometers. This shallow implantation layer is critical for scientific analysis of the composition of the solar wind and must be preserved throughout sample handling, cleaning, processing, distribution, preparation and analysis. We continue to work with the community of scientists analyzing Genesis samples using our unique laboratory facilities -- and, where needed, our unique cleaning techniques -- to significantly enhance the science return from the Genesis mission. This work is motivated by the need to understand the submicron contamination on the collectors in the Genesis payload as recovered from the crash site in the Utah desert, and -- perhaps more importantly -- how to remove it. We continue to evaluate the effectiveness of the wet-chemical "cleaning" steps used by various investigators, to enable them to design improved methods of stripping spacecraft and terrestrial contamination from surfaces while still leaving the solar-wind signal intact.

  14. Petrological Characteristic of Recent Eruption Events at Galeras Volcano, Colombia

    NASA Astrophysics Data System (ADS)

    Nakada, S.; Noguchi, S.; Cortes, G. P.; Calvache, M. L.

    2007-12-01

    On-going volcanic activity at Galeras began in 1988, and major explosive eruption events occurred in 1993. Long- period seismic events had occurred before these events. In late 2004, explosive eruptive events resumed and intermittently continued by the present. Long-period events similar to those before the 1993 explosive eruptive events have been observed since early 2006. Evaluating potential of more explosive future eruptions becomes very important to minimize volcanic disasters in cities and towns around this volcano, including the city of Pasto. Investigation of temporal changes in petrological characteristics of eruption products makes us possible to understand the magma system undergone at Galeras. Whether has it changed (or developed) from the 1993 explosive events or not? Ballistics and scoria of vulcanian explosions during 2004-2006 and of the 1991 eruption were investigated in this paper. Rocks are two pyroxene andesite with various crystallinity in groundmass. Small amount of hornblende and olivine microphenocrsyts are involved. The whole rock chemistry hardly changed with time. Lines of petrological evidence suggest that magma mixing occurred throughout the eruption products during 1991-2006; 1) bimodal populations in core compositions of plagioclase phenocrysts, 2) plagioclase microlites with the composition between the two polulations, 3) plagioclase phenocrysts rims more enriched in Fe, and 4) reverse zoning of pyroxene phenocrysts that rather show single chemical population. Melt inclusions in pyroxene phenocrysts are slightly less evolved than the groundmass glass, suggesting that most pyroxenes were derived from felsic magma. These suggest mixing of low-temperature hydrous felsic magma with high-temperature anhydrous (pyroxene-free) mafic magma. Similarity in the petrographical characteristics and temperatures with the pyroxene geothermometry among all the samples shows that nearly constant mixing processes has been operated throughout the recent

  15. Morphotectonic and petrological variations along the southern Central Indian Ridge

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, Ranadhir; Iyer, Sridhar D.; Ray, Dwijesh; Karisiddaiah, S. M.; Drolia, Rajendra K.

    2016-04-01

    In order to ascertain the effect of geomorphic and tectonic domains on the formation, enrichment, and ascension of the ridge axis melt, structural and petrological data from a nearly 300-km-long axial stretch along the slow-to-intermediate-spreading (40-60 mm/year) southern Central Indian Ridge (SCIR) were studied. The stretch, approximately between 20°30'S and 23°07'S, was disturbed by two major tectonic features—Egeria transform fault in the north and the Gemino Fracture Zone in the south—besides eight other discontinuities of variable dimensions. This stretch was chosen to test the petrological variations and mechanisms of magma supply in four distinct geomorphic and tectonic regimes: a Ridge-Crest-Flank-Valley (RCFV), a Neo-Volcanic Zone (NVZ), a large transform discontinuity (LTD), and an overlapping spreading centre (OSC). The major and trace element geochemistry of 44 glass and 47 whole rocks, extent and depth of melting (Na8 and Fe8, respectively), and melt pristinity (Mg#) of the magma indicate that rocks along this stretch were probably sourced from a reasonably primitive melt generated at a relatively greater depth and later got accumulated in pockets at a shallower level before eruption. Petrochemical analysis, and isotopic composition and ratios suggest that in contrast to largely N-MORB type of rocks at RCFV and OSC areas, the rocks from LTD and NVZ locations show signatures of enrichment to transitional (T) and enriched (E) basalts. A model explaining possible processes of enrichment and ascending framework of the melt at different tectonic regimes along SCIR are discussed.

  16. Decontamination of Genesis Array Materials by UV Ozone Cleaning

    NASA Technical Reports Server (NTRS)

    Calaway, Michael J.; Burnett, D. S.; Rodriquez, M. C.; Sestak, S.; Allton, J. H.; Stansbery, E. K.

    2007-01-01

    Shortly after the NASA Genesis Mission sample return capsule returned to earth on September 8, 2004, the science team discovered that all nine ultra-pure semiconductor materials were contaminated with a thin molecular organic film approximately 0 to 100 angstroms thick. The organic contaminate layer, possibly a silicone, situated on the surface of the materials is speculated to have formed by condensation of organic matter from spacecraft off-gassing at the Lagrange 1 halo orbit during times of solar exposure. While the valuable solar wind atoms are safely secured directly below this organic contamination and/or native oxide layer in approximately the first 1000 angstroms of the ultra-pure material substrate, some analytical techniques that precisely measure solar wind elemental abundances require the removal of this organic contaminate. In 2005, Genesis science team laboratories began to develop various methods for removing the organic thin film without removing the precious material substrate that contained the solar wind atoms. Stephen Sestak and colleagues at Open University first experimented with ultraviolet radiation ozone (UV/O3) cleaning of several non-flight and flown Genesis silicon wafer fragments under a pure flowing oxygen environment. The UV/O3 technique was able to successfully remove organic contamination without etching into the bulk material substrate. At NASA Johnson Space Center Genesis Curation Laboratory, we have installed an UV/O3 cleaning devise in an ambient air environment to further experimentally test the removal of the organic contamination on Genesis wafer materials. Preliminary results from XPS analysis show that the UV/O3 cleaning instrument is a good non-destructive method for removing carbon contamination from flown Genesis array samples. However, spectroscopic ellipsometry results show little change in the thickness of the surface film. All experiments to date have shown UV/O3 cleaning method to be the best non-destructive method

  17. The petrology and petrogenesis of the Swaldale region, Motzfeldt Center, South Greenland

    NASA Astrophysics Data System (ADS)

    Reekie, Callum; Finch, Adrian

    2016-04-01

    Motzfeldt is one of several high-level alkaline plutonic centers that collectively define the mid-Proterozoic Gardar Province of South Greenland. Despite pyrochlore-hosted Ta-enrichment (± Nb-Zr-REE), the petrology, geochemistry and petrogenesis across the center remain to be fully constrained. We present petrological and geochemical data for the Swaldale region, an arcuate band of nepheline syenite and associated intrusives on Motzfeldt's NW margin. Work for this present study was undertaken in collaboration with the license holder, Regency Mines plc. Swaldale comprises two geochemically distinct magmatic members. The largest, the Motzfeldt Sø Formation (MSF; EuN/Eu*N = 0.35), is a suite of diverse syenite variants that show significant petrological and geochemical heterogeneity. These rocks have a relatively restricted SiO2 range (57.4-62.9 wt.%) with concurrent variation in (Na+K)/Al (0.75-0.95), Mg/(Mg+Fe) (2.18-19.82) and ΣREE (595.0-3095.9 ppm), emphasizing their evolved but not peralkaline nature. Fractionation is mirrored by pyroxene geochemistry with evolution from aegirine-augite, aegirine-hedenbergite, to aegirine. Accessory pyrochlore, titanite, and zircon are rare; however, anomalous facies of zircon-rich (~2 wt.%) syenite are observed. Intercumulus fluorite is a common accessory within MSF rocks. Hydrothermal alteration, marked by hematized alkali-feldspar, is pervasive and ubiquitous. Further peraluminous syenite of the Geologfjeld Formation ((Na+K)/Al = 0.74; EuN/Eu*N = 1.60) marks the truncated remnant of an early syenite stock to the north of the MSF. These rocks contain salite, which, in addition to a lower ΣREE and higher Mg/(Mg+Fe) (18.01), demonstrates the less-fractionated nature of this stock in comparison with the MSF. Sheeted intrusions of peralkaline syenite ((Na+K)/Al = 1.1; Ta = 32.4 ppm) truncate the MSF across central Swaldale. On a mineralogical basis, it is hypothesized that such intrusions reflect outward sheeting of the

  18. Python as a federation tool for GENESIS 3.0.

    PubMed

    Cornelis, Hugo; Rodriguez, Armando L; Coop, Allan D; Bower, James M

    2012-01-01

    The GENESIS simulation platform was one of the first broad-scale modeling systems in computational biology to encourage modelers to develop and share model features and components. Supported by a large developer community, it participated in innovative simulator technologies such as benchmarking, parallelization, and declarative model specification and was the first neural simulator to define bindings for the Python scripting language. An important feature of the latest version of GENESIS is that it decomposes into self-contained software components complying with the Computational Biology Initiative federated software architecture. This architecture allows separate scripting bindings to be defined for different necessary components of the simulator, e.g., the mathematical solvers and graphical user interface. Python is a scripting language that provides rich sets of freely available open source libraries. With clean dynamic object-oriented designs, they produce highly readable code and are widely employed in specialized areas of software component integration. We employ a simplified wrapper and interface generator to examine an application programming interface and make it available to a given scripting language. This allows independent software components to be 'glued' together and connected to external libraries and applications from user-defined Python or Perl scripts. We illustrate our approach with three examples of Python scripting. (1) Generate and run a simple single-compartment model neuron connected to a stand-alone mathematical solver. (2) Interface a mathematical solver with GENESIS 3.0 to explore a neuron morphology from either an interactive command-line or graphical user interface. (3) Apply scripting bindings to connect the GENESIS 3.0 simulator to external graphical libraries and an open source three dimensional content creation suite that supports visualization of models based on electron microscopy and their conversion to computational models

  19. The Plasma Ion and Electron Instruments for the Genesis Mission

    NASA Astrophysics Data System (ADS)

    Barraclough, B. L.; Dors, E. E.; Abeyta, R. A.; Alexander, J. F.; Ameduri, F. P.; Baldonado, J. R.; Bame, S. J.; Casey, P. J.; Dirks, G.; Everett, D. T.; Gosling, J. T.; Grace, K. M.; Guerrero, D. R.; Kolar, J. D.; Kroesche, J. L., Jr.; Lockhart, W. L.; McComas, D. J.; Mietz, D. E.; Roese, J.; Sanders, J.; Steinberg, J. T.; Tokar, R. L.; Urdiales, C.; Wiens, R. C.

    2003-01-01

    The Genesis Ion Monitor (GIM) and the Genesis Electron Monitor (GEM) provide 3-dimensional plasma measurements of the solar wind for the Genesis mission. These measurements are used onboard to determine the type of plasma that is flowing past the spacecraft and to configure the solar wind sample collection subsystems in real-time. Both GIM and GEM employ spherical-section electrostatic analyzers followed by channel electron multiplier (CEM) arrays for detection and angle and energy/charge analysis of incident ions and electrons. GIM is of a new design specific to Genesis mission requirements whereas the GEM sensor is an almost exact copy of the plasma electron sensors currently flying on the ACE and Ulysses spacecraft, albeit with new electronics and programming. Ions are detected at forty log-spaced energy levels between ˜ 1 eV and 14 keV by eight CEM detectors, while electrons with energies between ˜ 1 eV and 1.4 keV are measured at twenty log-spaced energy levels using seven CEMs. The spin of the spacecraft is used to sweep the fan-shaped fields-of-view of both instruments across all areas of the sky of interest, with ion measurements being taken forty times per spin and samples of the electron population being taken twenty four times per spin. Complete ion and electron energy spectra are measured every ˜ 2.5 min (four spins of the spacecraft) with adequate energy and angular resolution to determine fully 3-dimensional ion and electron distribution functions. The GIM and GEM plasma measurements are principally used to enable the operational solar wind sample collection goals of the Genesis mission but they also provide a potentially very useful data set for studies of solar wind phenomena, especially if combined with other solar wind data sets from ACE, WIND, SOHO and Ulysses for multi-spacecraft investigations.

  20. Python as a Federation Tool for GENESIS 3.0

    PubMed Central

    Cornelis, Hugo; Rodriguez, Armando L.; Coop, Allan D.; Bower, James M.

    2012-01-01

    The GENESIS simulation platform was one of the first broad-scale modeling systems in computational biology to encourage modelers to develop and share model features and components. Supported by a large developer community, it participated in innovative simulator technologies such as benchmarking, parallelization, and declarative model specification and was the first neural simulator to define bindings for the Python scripting language. An important feature of the latest version of GENESIS is that it decomposes into self-contained software components complying with the Computational Biology Initiative federated software architecture. This architecture allows separate scripting bindings to be defined for different necessary components of the simulator, e.g., the mathematical solvers and graphical user interface. Python is a scripting language that provides rich sets of freely available open source libraries. With clean dynamic object-oriented designs, they produce highly readable code and are widely employed in specialized areas of software component integration. We employ a simplified wrapper and interface generator to examine an application programming interface and make it available to a given scripting language. This allows independent software components to be ‘glued’ together and connected to external libraries and applications from user-defined Python or Perl scripts. We illustrate our approach with three examples of Python scripting. (1) Generate and run a simple single-compartment model neuron connected to a stand-alone mathematical solver. (2) Interface a mathematical solver with GENESIS 3.0 to explore a neuron morphology from either an interactive command-line or graphical user interface. (3) Apply scripting bindings to connect the GENESIS 3.0 simulator to external graphical libraries and an open source three dimensional content creation suite that supports visualization of models based on electron microscopy and their conversion to computational

  1. Learning Activities for an Undergraduate Mineralogy/Petrology Course-"I Am/We Are."

    ERIC Educational Resources Information Center

    Goodell, Philip C.

    2001-01-01

    Introduces an entry level mineralogy/igneous petrology course designed for undergraduate students and presents a series of learning activities based on individual and cooperative learning. Includes 18 references. (Author/YDS)

  2. Petrology and Geochemistry of New Paired Martian Meteorites Larkman Nunatak 12240 and Larkman Nunatak 12095

    NASA Astrophysics Data System (ADS)

    Funk, R. C.; Peslier, A. H.; Brandon, A. D.; Humayun, M.

    2016-08-01

    Two of the latest Martian meteorites found in Antarctica, paired olivine-phyric shergottites LAR 12240 and LAR 12095, are described in order to decipher their petrological context, and place constraints on the geological history of Mars.

  3. Petrologic constraints on the pressure, temperature, time and composition of the Martian interior

    NASA Technical Reports Server (NTRS)

    Holloway, John R.

    1988-01-01

    Petrologic analysis of surface samples has been used to deduce pressure and temperature conditions existing in the crust and upper mantle at specific times in the Earth's history, as well as to estimate the chemical and mineralogical composition of the crust and upper mantle. The same techniques can be applied to samples of the Martian surface to provide P, T, time and composition constraints of the Martian interior. Estimates of P and T conditions existing at a given time would, in turn, provide strong constraints on the thermal evolution of Mars. Knowledge of the chemical and mineralogical composition of the Martian interior is of fundamental importance in assessing the early history of the solar system. A general petrological approach is outlined, describing the kinds of sample required, summarizing current understanding of the Martian interior based on experimental petrology, and outlining some of the important experiments needed to allow a full petrologic interpretation of Martian samples.

  4. 75 FR 52966 - Notice of Availability of the Final Environmental Impact Statement for the Genesis Solar, LLC...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-30

    ... Genesis Solar, LLC Genesis Solar Energy Project and Proposed California Desert Conservation Area Plan... Genesis Solar LLC's Genesis Solar Energy Project (GSEP) and by this notice is announcing its availability... amendment the CDCA Plan to make the area suitable for solar energy development; a reduced...

  5. JPL Genesis and Rapid Intensification Processes (GRIP) Portal

    NASA Technical Reports Server (NTRS)

    Knosp, Brian W.; Li, P. Peggy; Vu, Quoc A.; Turk, Francis J.; Shen, Tsae-Pyng J.; Hristova-Veleva, Svetla M.; Licata, Stephen J.; Poulsen, William L.

    2012-01-01

    Satellite observations can play a very important role in airborne field campaigns, since they provide a comprehensive description of the environment that is essential for the experiment design, flight planning, and post-experiment scientific data analysis. In the past, it has been difficult to fully utilize data from multiple NASA satellites due to the large data volume, the complexity of accessing NASA s data in near-real-time (NRT), as well as the lack of software tools to interact with multi-sensor information. The JPL GRIP Portal is a Web portal that serves a comprehensive set of NRT observation data sets from NASA and NOAA satellites describing the atmospheric and oceanic environments related to the genesis and intensification of the tropical storms in the North Atlantic Ocean. Together with the model forecast data from four major global atmospheric models, this portal provides a useful tool for the scientists and forecasters in planning and monitoring the NASA GRIP field campaign during the 2010 Atlantic Ocean hurricane season. This portal uses the Google Earth plug-in to visualize various types of data sets, such as 2D maps, wind vectors, streamlines, 3D data sets presented at series of vertical cross-sections or pointwise vertical profiles, and hurricane best tracks and forecast tracks. Additionally, it allows users to overlap multiple data sets, change the opacity of each image layer, generate animations on the fly with selected data sets, and compare the observation data with the model forecast using two independent calendars. The portal also provides the capability to identify the geographic location of any point of interest. In addition to supporting the airborne mission planning, the NRT data and portal will serve as a very rich source of information during the post-field campaign analysis stage of the airborne experiment. By including a diverse set of satellite observations and model forecasts, it provides a good spatial and temporal context for the

  6. New evolutionary insights into granite genesis preserved in the trace element compositions of apatite and zircon

    NASA Astrophysics Data System (ADS)

    Miles, A.; Graham, C.; Gillespie, M.; Hawkesworth, C. J.; Hinton, R. W.

    2010-12-01

    The chemical architecture of key accessory minerals like zircon and apatite has proved pivotal in assessing the early mechanisms of crustal growth and differentiation. However, the exact stages at which they crystallise during the evolution of granite plutons and the processes they record remain poorly constrained. We present a combined micro-analytical and petrological study of these important accessory minerals. The results reveal the significance of early and previously unrecognised incremental assembly of intermediate zones in the I-type (margins) to S-type (centre) zoned Scottish Caledonian pluton, Criffel. Within intermediate zones, two distinct I- and S-type trends are seen in trace element compositions of apatites enclosed by zircon and other major phases respectively (Fig. 1). The fluorine concentrations of apatite included within different phases have been used as a proxy for the degree of melt differentiation and S-type melt involvement, and indicate that zircon-hosted apatite compositions often preserve the earliest and most primitive record of I-type magmas. Together with textural evidence, this provides some of the first geochemical evidence that zircon started crystallising at a relatively early stage of magma evolution, placing important constraints on the interpretations of zircon O and Hf isotopic data. The systematic increase in δ18O from ~6‰ to >8‰ recorded by zircon from progressively more central zones of the pluton requires additions of an 18O-enriched component to the magma. Near-Gaussian zircon 18O probability distributions indicate effective magma mixing prior to zircon crystallisation, yet differences of up to 4‰ between zircon and their host whole-rock δ18O values demonstrate isotopic disequilibrium and early crystallisation of zircon from a magma of lower δ18O. Thus, the earliest records of magmatic processes indicate that final intermediate bulk compositions are primarily the product of both I- and S-type magma components

  7. Isotopic Petrology: The Curious Case of the Shergottite Meteorites

    NASA Astrophysics Data System (ADS)

    Jones, J. H.

    2009-05-01

    The shergottites comprise a diverse suite of martian basalts and basaltic cumulates. As of 1985, there were three proposed igneous ages for this group of basaltic rocks: (i) 4-4.5 b.y. [1; Caltech]; (ii) 1.3 b.y. [2; JSC]; and (iii) 360 m.y. [3; Mainz]. At that time I proffered that petrographic observations demanded that the shergottites were only 180 m.y. old [4]. By 1985, all the above geochronology groups had presented evidence of a young 200 m.y. age, but interpreted that as a metamorphic resetting. My observation was considered extremely controversial. However, John Longhi was instrumental, perhaps pivotal, in causing this new, controversial interpretation to be accepted, at least among petrologists. John then used this newfound knowledge to infer the Nd isotopic composition of the martian crust [5]. This new interpretation of shergottite chronology has led to petrologic insights that would not otherwise have been possible: (I) There were melt extraction events in the shergottite mantle immediately(?) preceding shergottite formation; and (II) the variation in enriched vs. depleted characteristics of the shergottites is best explained by assimilation of ancient, enriched crust by young magmas from a depleted source region. I. Internal, mineral isochrons of the shergottites (15 years later) vary from 165 m.y. to 575 m.y. [6]. Without exception, the Sm/Nd ratios of the shergottites themselves are larger than the time-integrated Sm/Nd ratio of their source regions [7]. This means that there has been a LREE-enriched phase that has fractionated from the shergottites. There are no solid phases in the martian mantle that are capable of this. This implies that LREE-enriched magmas escaped the shergottite source regions just prior to shergottite petrogenesis. II. Therefore, the shergottites can be characterized in terms of three Sm-Nd components: (i) a primitive shergottite magma from a depleted source region; (ii) an enriched crust; and (iii) a missing LREE

  8. Rethinking how Undergraduate ``Hard Rock'' Petrology is Taught

    NASA Astrophysics Data System (ADS)

    Reid, M. R.

    2010-12-01

    A course in "hard rock" petrology forms a core component of undergraduate training in the geosciences. In most cases, the subjects of igneous and metamorphic petrology are combined in a single course and the course is traditionally structured so that the two subjects are covered in series. This approach enables students to focus on each subject separately, with knowledge of igneous rocks helping students to understand metamorphic rock protoliths. Student assessment shows, however, that this approach tends to compartmentalize learning and the two main subjects might just as well be taught in separate courses. In practical applications such as fieldwork, students must be able to access their understanding of igneous and metamorphic rocks virtually simultaneously. To better integrate student learning, I developed a spiral learning approach to teaching petrology (e.g., Bruner, 1990; Dyar et al., 2004) so that commonalities could be revisited several times over the course of a semester and, in so doing, students' grasp of the fundamental insights provided by igneous and metamorphic rocks could be scaffolded into greater understanding. The course initially focuses on the dynamics of the environments in which igneous and metamorphic rocks form: heat flow, fluid flow, and plate tectonics. Several subsequent weeks explore topics relevant to identifying and understanding igneous and metamorphic rocks in the field: crystal nucleation and growth, the roles of pressure and heat, and field classification. Laboratory exercises parallel this structure, also emphasizing observations that are valuable in the field: the relationship between minerals and rocks, textural observations, and general rock classification. The final portion of the course explores “hard rocks” in more detail with a greater emphasis on the interplay between chemistry and mineralogy. A variety of learner-centered activities in the course help students bridge the gap between novice and expert and include

  9. Geochemistry, petrology, and palynology of the Pond Creek coal bed, northern Pike and southern Martin counties, Kentucky

    USGS Publications Warehouse

    Hower, J.C.; Ruppert, L.F.; Eble, C.F.; Clark, W.L.

    2005-01-01

    The geochemistry, petrology, and palynology of the Duckmantian-age Pond Creek coal bed were investigated in northern Pike and southern Martin counties, eastern Kentucky. The coal bed exhibits significant vertical variation in the investigated geochemical parameters, with many diagenetic overprints of the original geochemistry. Included in the range of geochemical signatures are the presence of elements, particularly TiO2 and Zr, suggesting the detrital influences at the time of deposition of a low-vitrinite durain; a high CaO zone with elevated B/Be, both suggesting marine influence, in a lithotype in the middle of the coal bed; and the postdepositional emplacement of pyrite in the uppermost lithotype. Individual lithotypes, each representing distinct depositional environments, all complicated to some degree by diagentic overprints, comprise the complex history of the coal bed. ?? 2004 Elsevier B.V. All rights reserved.

  10. Entry Dispersion Analysis for the Genesis Sample Return Capsule

    NASA Technical Reports Server (NTRS)

    Desai, Prasun N.; Cheatwood, F. McNeil

    2005-01-01

    Genesis will be the first mission to return samples from beyond the Earth-Moon system. The spacecraft will be inserted into a halo orbit about the L1 (Sun-Earth) libration point where it will remain for two years collecting solar wind particles. Upon Earth return, the sample return capsule, which is passively controlled, will descend under parachute to Utah. The present study describes the analysis of the entry, descent, and landing scenario of the returning sample capsule. The robustness of the entry sequence is assessed through a Monte Carlo dispersion analysis where the impact of off-nominal conditions is ascertained. The dispersion results indicate that the capsule attitude excursions near peak heating and drogue chute deployment are within Genesis mission limits. Additionally, the size of the resulting 3-sigma landing ellipse is 47.8 km in downrange by 15.2 km in crossrange, which is within the Utah Test and Training Range boundaries.

  11. Analysis of Molecular Contamination on Genesis Collectors Through Spectroscopic Ellipsometry

    NASA Technical Reports Server (NTRS)

    McNamara, K. M.; Stansbery, Eileen K.

    2005-01-01

    Before the spacecraft returned to Earth in September, the Genesis mission had a preliminary assessment plan in place for the purpose of providing information on the condition and availability of collector materials to the science community as a basis for allocation requests. One important component of that plan was the evaluation of collector surfaces for molecular contamination. Sources of molecular contamination might be the on-orbit outgassing of spacecraft and science canister components, the condensation of thruster by-products during spacecraft maneuvers, or the condensation of volatile species associated with reentry. Although the non-nominal return of the Genesis spacecraft introduced particulate contamination to the collectors, such as dust and heatshield carbon-carbon, it is unlikely to have caused any molecular deposition. The contingency team's quick action in returning the damaged payload the UTTR cleanroom by 6 PM the evening of recovery help to ensure that exposure to weather conditions and the environment were kept to a minimum.

  12. Entry Dispersion Analysis for the Genesis Sample Return Capsule

    NASA Technical Reports Server (NTRS)

    Desai, Prasun N.; Cheatwood, F. McNeil

    1999-01-01

    Genesis will be the first mission to return samples from beyond the Earth-Moon system. The spacecraft will be inserted into a halo orbit about the L1 (Sun- Earth) libration point where it will remain for two years collecting solar wind particles. Upon Earth return, the sample return capsule, which is passively controlled, will descend under parachute to Utah. The present study describes the analysis of the entry, descent, and landing scenario of the returning sample capsule. The robustness of the entry sequence is assessed through a Monte Carlo dispersion analysis where the impact of off-nominal conditions is ascertained. The dispersion results indicate that the capsule attitude excursions near peak heating and drogue chute deployment are within Genesis mission limits. Additionally, the size of the resulting 3-sigma landing ellipse is 47.8 km in downrange by 15.2 km in crossrange, which is within the Utah Test and Training Range boundaries.

  13. Entry Dispersion Analysis for the Genesis Sample Return Capsule

    NASA Technical Reports Server (NTRS)

    Desai, Prasun, N.; Cheatwood, F. McNeil

    1999-01-01

    Genesis will be the first mission to return samples from beyond the Earth-Moon system. The spacecraft will be inserted into a halo orbit about the L1 (Sun- Earth) libration point where it will remain for two years collecting solar wind particles. Upon Earth return, the sample return capsule, which is passively controlled, will descend under parachute to Utah. The present study describes the analysis of the entry, descent, and landing scenario of the returning sample cap- sule. The robustness of the entry sequence is assessed through a Monte Carlo dispersion analysis where the impact of off-nominal conditions is ascertained. The dispersion results indicate that the capsule attitude excursions near peak heating and drogue chute deployment are within Genesis mission limits. Additionally, the size of the resulting 3-sigma landing ellipse is 47.8 km in downrange by 15.2 km in crossrange, which is within the Utah Test and Training Range boundaries.

  14. Nuts and Bolts - Techniques for Genesis Sample Curation

    NASA Technical Reports Server (NTRS)

    Burkett, Patti J.; Rodriquez, M. C.; Allton, J. H.

    2011-01-01

    The Genesis curation staff at NASA Johnson Space Center provides samples and data for analysis to the scientific community, following allocation approval by the Genesis Oversight Committee, a sub-committee of CAPTEM (Curation Analysis Planning Team for Extraterrestrial Materials). We are often asked by investigators within the scientific community how we choose samples to best fit the requirements of the request. Here we will demonstrate our techniques for characterizing samples and satisfying allocation requests. Even with a systematic approach, every allocation is unique. We are also providing updated status of the cataloging and characterization of solar wind collectors as of January 2011. The collection consists of 3721 inventoried samples consisting of a single fragment, or multiple fragments containerized or pressed between post-it notes, jars or vials of various sizes.

  15. [Genesis study of omphacite at high pressure and high temperature].

    PubMed

    Xiao, Ben-Fu; Yi, Li; Wang, Duo-Jun; Xie, Chao; Tang, Xue-Wu; Liu, Lei; Cui, Yue-Ju

    2013-11-01

    The melting and recrystallizing experiments of alkali basalt powder and mixture of pure oxides mixed as stoichiometry were performed at 3 GPa and 1 200 degrees C. Electronic microprobe analysis and Raman spectra showed that the recrystallized products were omphacites, the FWHM (full width at half maximum) of the Raman peak was narrow and its shape was sharp, which is attributed to the stable Si-O tetrahedral structure and the high degree of order in omphacite. Based on the results of previous studies, the influencing factors of omphacite genesis and its primary magma were discussed. The results showed that the formation of omphacite could be affected by many factors, such as the composition of parent rocks, the concentration of fluid in the system and the conditions of pressure and temperature. This result could support some experimental evidences on the genesis studies of omphacite and eclogite.

  16. EV13 Genesis Reentry Observations and Data Analysis

    NASA Technical Reports Server (NTRS)

    Swift, Wesley R.; Suggs, Robert M.

    2006-01-01

    The Genesis spacecraft reentry represented a unique opportunity to observe a "calibrated meteor" from northern Nevada. Knowing its speed, mass, composition, and precise trajectory made it a good subject to test some of the algorithms used to determine meteoroid mass from observed brightness. It was also a good test of an inexpensive set of cameras which could be deployed to observe future shuttle reentries. The utility of consumer grade video cameras was evident during the STS-107 accident investigation and the Genesis reentry gave us the opportunity to specify and test commercially available cameras which could be used during future reentries. This report describes the video observations and their analysis, compares the results with a simple photometric model, describes the forward scatter radar experiment, and lists lessons learned from the expedition and implications for the Stardust reentry in January 2006 as well as future shuttle reentries.

  17. Genesis of Typhoon Nari (2001) from a mesoscale convective system

    NASA Astrophysics Data System (ADS)

    Zhang, Da-Lin; Tian, Liqing; Yang, Ming-Jen

    2011-12-01

    In this study, the origin and genesis of Typhoon Nari (2001) as well as its erratic looping track, are examined using large-scale analysis, satellite observations, and a 4 day nested, cloud-resolving simulation with the finest grid size of 1.33 km. Observational analysis reveals that Nari could be traced 5 days back to a diurnally varying mesoscale convective system with growing cyclonic vorticity and relative humidity in the lower troposphere and that it evolved from a mesoscale convective vortex (MCV) as moving over a warm ocean under the influence of a subtropical high, a weak westerly baroclinic disturbance, an approaching-and-departing Typhoon Danas to the east, and the Kuroshio Current. Results show that the model reproduces the genesis, final intensity, looping track, and the general convective activity of Nari during the 4 day period. It also captures two deep subvortices at the eye-eyewall interface that are similar to those previously observed, a few spiral rainbands, and a midget storm size associated with Nari's relatively dry and stable environment. We find that (1) continuous convective overturning within the MCV stretches the low-level vorticity and moistens a deep mesoscale column that are both favorable for genesis; (2) Nari's genesis does not occur until after the passage of the baroclinic disturbance; (3) convective asymmetry induces a smaller-sized vortex circulation from the preexisting MCV; (4) the vortex-vortex interaction with Danas leads to Nari's looping track and temporal weakening; and (5) midlevel convergence associated with the subtropical high and Danas accounts for the generation of a nearly upright eyewall.

  18. Size Distribution of Genesis Solar Wind Array Collector Fragments Recovered

    NASA Technical Reports Server (NTRS)

    Allton, J. H.; Stansbery, E. K.; McNamara, K. M.

    2005-01-01

    Genesis launched in 2001 with 271 whole and 30 half hexagonally-shaped collectors mounted on 5 arrays, comprised of 9 materials described in [1]. The array collectors were damaged during re-entry impact in Utah in 2004 [2], breaking into many smaller pieces and dust. A compilation of the number and approximate size of the fragments recovered was compiled from notes made during the field packaging performed in the Class 10,000 cleanroom at Utah Test and Training Range [3].

  19. Tropical Cyclone Genesis Efficiency: Mid-Level Versus Bottom Vortex

    DTIC Science & Technology

    2011-12-16

    an environment with a near bottom vortex ( EBV ) and an environment with a mid-level vortex (EMV). Sensitivity experiments show that the genesis timing...Both the EMV and EBV scenarios share the following development characteristics: 1) a transition from non-organized cumulus-scale (~5 km) convective...disturbance develops into a TC. 15. SUBJECT TERMS 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT Same as Report (SAR) 18. NUMBER OF PAGES

  20. Dividing the Concentrator Target From the Genesis Mission

    NASA Technical Reports Server (NTRS)

    Lauer, H. V., Jr.; Burkett, P. J.; Clemett, S. J.; Gonzales, C. P.; Nakamura-Messenger, K.; Rodriquez, M. C.; See, T. H.; Sutter, B.

    2014-01-01

    The Genesis spacecraft, launched in 2001, traveled to a Lagrangian point between the Earth and Sun to collect particles from the solar wind and return them to Earth. However, during the return of the spacecraft in 2004, the parachute failed to open during descent, and the Genesis spacecraft crashed into the Utah desert. Many of the solar wind collectors were broken into smaller pieces, and the field team rapidly collected the capsule and collector pieces for later assessment. On each of the next few days, the team discovered that various collectors had survived intact, including three of four concentrator targets. Within a month, the team had imaged more than 10,000 fragments and packed them for transport to the Astromaterials Acquisition and Curation Office within the ARES Directorate at JSC. Currently, the Genesis samples are curated along with the other extraterrestrial sample collections within ARES. Although they were broken and dirty, the Genesis solar wind collectors still offered the science community the opportunity to better understand our Sun and the solar system as a whole. One of the more highly prized concentrator collectors survived the crash almost completely intact. The Genesis Concentrator was designed to concentrate the solar wind by a factor of at least 20 so that solar oxygen and nitrogen isotopes could be measured. One of these materials was the Diamond-on-Silicon (DoS) concentrator target. Unfortunately, the DoS concentrator broke on impact. Nevertheless, the scientific value of the DoS concentrator target was high. The Genesis Allocation Committee received a request for approximately 1 cm(sup 2) of the DoS specimen taken near the focal point of the concentrator for the analysis of solar wind nitrogen isotopes. The largest fragment, Genesis sample 60000, was designated for this allocation and needed to be precisely cut. The requirement was to subdivide the designated sample in a manner that prevented contamination of the sample and minimized

  1. Genesis Solar-Wind Sample Return Mission: The Materials

    NASA Technical Reports Server (NTRS)

    Jurewicz, A. J. G.; Burnett, D. S.; Wiens, R. C.; Woolum, D.

    2003-01-01

    The Genesis spacecraft has two primary instruments which passively collect solar wind. The first is the collector arrays , a set of panels, each of which can deploy separately to sample the different kinds of solar wind (regimes). The second is the concentrator, an electrostatic mirror which will concentrate ions of mass 4 through mass 25 by about a factor of 20 by focusing them onto a 6 cm diameter target. When not deployed, these instruments fit into a compact canister. After a two year exposure time, the deployed instruments can be folded up, sealed into the canister, and returned to earth for laboratory analysis. Both the collector arrays and the concentrator will contain suites of ultra-high purity target materials, each of which is tailored to enable the analysis of a different family of elements. This abstract is meant to give a brief overview of the Genesis mission, insight into what materials were chosen for flight and why, as well as head s up information as to what will be available to planetary scientist for analysis when the solar-wind samples return to Earth in 2003. Earth. The elemental and isotopic abundances of the solar wind will be analyzed in state-of-the-art laboratories, and a portion of the sample will be archived for the use of future generations of planetary scientists. Technical information about the mission can be found at www.gps.caltech.edu/genesis.

  2. Genesis of calc-alkali andesite magma in a hydrous mantle-crust boundary: Petrology of lherzolite xenoliths from the Ichinomegata crater, Oga peninsula, northeast Japan, part II

    NASA Astrophysics Data System (ADS)

    Takahashi, Eiichi

    1986-09-01

    The Ichinomegata volcano, northwestern Honshu, Japan, consisting of three explosion craters, is characterized by the presence of contemporaneous basalt (high-alkali tholeiite) and calc-alkali andesite and a variety of mafic and ultramafic xenoliths of deep-seated origin. The population of the rock types decreases exponentially as a function of increasing depth of their origin. Based on the Ichinomegata xenolith mineralogy, it is inferred that the lower crust and uppermost mantle beneath this area is partially hydrated, consisting dominantly of hornblende gabbro and hornblende-bearing spinel lherzolite, respectively. Chemical analysis on spinel-pyroxene symplectite (so called garnet pseudomorph) in some Ichinomegata lherzolites suggests a calcic-plagioclase primary chemistry rather than garnet. In lherzolite xenoliths which have undergone a preheating event, primary partial melting textures are observed. The composition of the glass formed along the grain boundaries of the partially melted lherzolites are similar to those produced in hydrous melting experiments on natural peridotite at about 10 kbar between 1000 and 1100°C. The high-alkali tholeiite and calc-alkali andesite of the Ichinomegata volcano are considered to have been formed by the following two-stage melting processes; (1) derivation of the basalt magma from partial melting of a peridotite diapir in the upper mantle at 40-50 km depth; (2) derivation of the calc-alkali andesite magma at 25-30 km depth by wet partial melting of the rocks at the mantle/crust boundary caused by emplacement of hot basaltic magma body. It is proposed that similar wet partial melting takes place more extensively beneath major island-arc volcanoes in the world, because the lower crust and the upper mantle beneath them may be hydrated due to continuous water supply from the subducting plate, and the amount of heat energy liberated at the mantle/crust boundary would be much larger in major stratovolcanoes than in the comparatively small Ichinomegata volcano. From consideration of energy balances, it is expected that the calc-alkali magma formed by this mechanism will be similar in volume to the hot basaltic magma solidified in the deep crust, and the base of the crust is the most likely site where substantial amounts of calc-alkali magma can be produced. It is emphasized that the model accords well with various constraints on the petrogenesis of calc-alkali rocks, among which most important are: (1) within the history of an island-arc volcano, calc-alkali rocks (andesite and dacite) occur in association with tholeiitic or alkalic rocks; (2) the ratio of calc-alkali rocks to other rocks (basalts and their derivatives) increases systematically with average crustal thickness beneath the volcanic belt; (3) calc-alkali rocks frequently show evidence of magma mixing.

  3. A model for genesis of transcription systems.

    PubMed

    Burton, Zachary F; Opron, Kristopher; Wei, Guowei; Geiger, James H

    2016-01-01

    Repeating sequences generated from RNA gene fusions/ligations dominate ancient life, indicating central importance of building structural complexity in evolving biological systems. A simple and coherent story of life on earth is told from tracking repeating motifs that generate α/β proteins, 2-double-Ψ-β-barrel (DPBB) type RNA polymerases (RNAPs), general transcription factors (GTFs), and promoters. A general rule that emerges is that biological complexity that arises through generation of repeats is often bounded by solubility and closure (i.e., to form a pseudo-dimer or a barrel). Because the first DNA genomes were replicated by DNA template-dependent RNA synthesis followed by RNA template-dependent DNA synthesis via reverse transcriptase, the first DNA replication origins were initially 2-DPBB type RNAP promoters. A simplifying model for evolution of promoters/replication origins via repetition of core promoter elements is proposed. The model can explain why Pribnow boxes in bacterial transcription (i.e., (-12)TATAATG(-6)) so closely resemble TATA boxes (i.e., (-31)TATAAAAG(-24)) in archaeal/eukaryotic transcription. The evolution of anchor DNA sequences in bacterial (i.e., (-35)TTGACA(-30)) and archaeal (BRE(up); BRE for TFB recognition element) promoters is potentially explained. The evolution of BRE(down) elements of archaeal promoters is potentially explained.

  4. A model for genesis of transcription systems

    PubMed Central

    Burton, Zachary F.; Opron, Kristopher; Wei, Guowei; Geiger, James H.

    2016-01-01

    ABSTRACT Repeating sequences generated from RNA gene fusions/ligations dominate ancient life, indicating central importance of building structural complexity in evolving biological systems. A simple and coherent story of life on earth is told from tracking repeating motifs that generate α/β proteins, 2-double-Ψ−β-barrel (DPBB) type RNA polymerases (RNAPs), general transcription factors (GTFs), and promoters. A general rule that emerges is that biological complexity that arises through generation of repeats is often bounded by solubility and closure (i.e., to form a pseudo-dimer or a barrel). Because the first DNA genomes were replicated by DNA template-dependent RNA synthesis followed by RNA template-dependent DNA synthesis via reverse transcriptase, the first DNA replication origins were initially 2-DPBB type RNAP promoters. A simplifying model for evolution of promoters/replication origins via repetition of core promoter elements is proposed. The model can explain why Pribnow boxes in bacterial transcription (i.e., −12TATAATG−6) so closely resemble TATA boxes (i.e., −31TATAAAAG−24) in archaeal/eukaryotic transcription. The evolution of anchor DNA sequences in bacterial (i.e., −35TTGACA−30) and archaeal (BREup; BRE for TFB recognition element) promoters is potentially explained. The evolution of BREdown elements of archaeal promoters is potentially explained. PMID:26735411

  5. Petrology of four clasts from consortium breccia 73215

    NASA Technical Reports Server (NTRS)

    James, O. B.; Hammarstrom, J. G.

    1977-01-01

    One felsite ('granite') and three ANT-suite anorthositic gabbro clasts extracted from breccia 73215 are described. The felsite clast has two components - fragments of crystalline felsite and veins and patches of felsic glass. The crystalline felsite, which consists largely of a vermicular intergrowth of quartz and Ba-K-feldspar, crystallized from a highly differentiated melt between 3.90 and 4.05 b.y. The felsic glass component consists of crystallized brown and colorless glasses and uncrystallized colorless glass which are all K and Si rich. The relation of glass features to past heating and the breccia-forming event is considered. In the three anorthositic gabbros, which have similar mineralogies and gradational textures, plagioclase is dominant, and olivine and orthopyroxene are the major mafic minerals. The petrologic data suggest that the gabbros formed as heated, partly melted, and/or recrystallized polymict breccias. It is possible that the approximately 4.25 b.y. age obtained for the three rocks is the date of the melting/recrystallization event.

  6. A new fitting algorithm for petrological mass-balance problems

    NASA Astrophysics Data System (ADS)

    Krawczynski, M. J.; Olive, J. L.

    2011-12-01

    We present a suite of Matlab programs aimed at solving linear mixing problems in which a composition must be assessed as the convex linear mixture of a known number of end-member compositions (e.g. mineral and melt chemical analyses). It is often the case in experimental petrology that answering a geochemical question involves solving a system of linear mass balance equations. Calculating phase proportions of an experimental charge to determine crystallinity, comparing experimental phase compositions to determine melting/crystallization reactions, and checking the chemical closure of your experimental system, are a few examples of these types of problems. Our algorithm is based on the isometric log-ratio transform, a one-to-one mapping between composition space and an "unconstrained" Euclidian space where standard inversion procedures apply (Egozcue et al., 2003). It allows the consideration of a-priori knowledge and uncertainties on endmember and bulk compositions as well as phase-proportions. It offers an improvement over the typical compositional space algorithms (Bryan et al., 1969; Albarede and Provost, 1977). We have tested our method on synthetic and experimental data sets, and report the uncertainties on phase abundances. The algorithm presented here eliminates the common problem of calculated phase proportions that produce negative mass balance coefficients. In addition, we show how the method can be used to estimate uncertainties on the coefficients for experimentally determined mantle melting equations.

  7. Isotopic, petrologic and biogeochemical investigations of banded iron-formations

    NASA Technical Reports Server (NTRS)

    Hayes, J. M.; Kaufman, A. J.; Klein, C.; Studley, S. A.; Baur, M. E.; Walter, M. R.

    1986-01-01

    It is recognized that the first occurrence of banded iron-formations (BIFs) clearly predates biological oxygenation of the atmosphere-hydrosphere system and that their last occurrences extend beyond plausible dates of pervasive biological oxygenation. For this reason, and because enormous quantities of oxidizing power have been sequestered in them, it is widely thought that these massive, but enigmatic, sediments must encode information about the mechanism and timing of the rise of atmospheric O2. By coupling isotopic analyses of iron-formation carbonates with biogeochemical and petrologic investigations, we are studying (1) the mechanism of initial sedimentation of iron; (2) the role of iron in microbially mediated diagenetic processes in fresh iron-formation sediments; and (3) the logical integration of mechanisms of deposition with observed levels of banding. Thus far, it has been shown that (1) carbonates in BIFs of the Hamersley Group of Western Australia are isotopically inhomogenous; (2) the nature and pattern of isotopic ordering is not consistent with a metamorphic origin for the overall depletion of C-13 observed in the carbonates; (3) if biological, the origin of the C-13 depleted carbonate could be either respiratory or fermentative; (4) iron may have been precipitate d as Fe(3+), then reduced to Fe(2+) within the sediment; and (5) sedimentary biogeochemical systems may have been at least partially closed to mass transport of carbonate species.

  8. Petrology of Zircon-Bearing Diogenite Northwest Africa 10666

    NASA Technical Reports Server (NTRS)

    Tanner, T. B.; Jeffcoat, C. R.; Righter, M.; Berger, E. L.; Lapen, T. J.; Irving, A. J.; Kuehner, S. M.; Fujihara, G.

    2017-01-01

    The howardite, eucrite, and diogenite (HED) meteorites are a group of achondrites thought to be derived from the asteroid 4 Vesta, though there is active debate as to whether all diogenites are part of the HED suite. Petrologic investigation of the HED meteorite group provides a means of understanding early planetary differentiation processes and early evolution of planets in our solar system. Diogenites are predominantly coarse grained ortho-pyroxenites with some samples containing appreciable amounts of clinopyroxene, olivine, chromite, and plagioclase. Accessory metal, troilite, and apatite are common. Many diogenites are brecciated, however, there are few poorly to unbrecciated samples. Diogenites are important because they may represent the lower crust of 4 Vesta. Although Mg isotope data indicates that the sources of diogenites are ancient, their crystallization ages are difficult to constrain due to their protracted thermal histories. The limited chronologic data for diogenites also limits the ability to test petrogenetic connections with eucrites and even parent body. A reliable and high closure-temperature isotope system, such as U-Pb in zircon, is needed to address the timing of diogenite igneous crystallization. Description of the textures and mineralogy of diogenites are essential to their classification and understanding their formation, in particular, whether all phases are petrogenetically related. Here, we present detailed petrographic data from a rare zircon-bearing feldspathic diogenite, Northwest Africa (NWA) 10666 and provide textural evidence for igneous crystallization of the zircon.

  9. Petrology of pseudotachylytes from the Alpine Fault of New Zealand

    NASA Astrophysics Data System (ADS)

    Bossière, G.

    1991-09-01

    The petrology of pseudotachylytes derived from contrasting host rocks within the Alpine Fault of New Zealand, a well known dextral shear zone, is presented. The structural observations indicate that parallel synthetic shears formed first in a non-dilational system, at low angles to the Alpine Fault. Then, between these shears, fracturing and frictional heating occured according to a new, dilational, Riedel system, accompanied by listric faults. The observations suggest that pseudotachylyte melt is mainly formed in the listric faults and channelled into neighbouring areas of extension. Pseudotachylyte results from in situ melting and its nature depend strictly on the parent rock mineralogy. The microlitic nature of the pseudotachylites is confirmed, and the variability of the textures explained in terms of degrees of undercooling. The morphology and composition of the minerals in the pseudotachylyte (plagioclase, biotite and amphibole) are documented. They crystallized at a higher temperature and pressure than their parent rock minerals. The melting process is believed to be governed by the mechanical properties of mafic minerals, in a fluid-free environment at the beginning of the melting. Mafic minerals provide water which allows the development of the pseudotachylyte.

  10. Ultrastructural observation on genesis and morphology of cortical granules in Macrobrachium nipponense (Crustacea, Caridea).

    PubMed

    Zhang, Tian-Ting; Jiang, Ye-Qin; Zhou, Hong; Yang, Wan-Xi

    2010-01-01

    Cortical granules are secretory vesicles in oocytes that develop from the Golgi complex. In the freshwater shrimp, Macrobrachium nipponense, mitochondria participates in the formation of cortical granules. We investigated the structural changes of mitochondria and the distribution cortical granules in different stages of oocyte development. Transmission electron microscopy provided evidence for the involvement of mitochondria and a particular spiral lamellar organization and an electron-lucent area in internal cortical granules. The ooplasm provided material for the cortical granules in early oocyte development. We demonstrated that mitochondria play a role in coalescence and maturation of cortical granules in this species. Additionally, a concept of cortical granules regarded as a functional integration is put forward. The genesis of shrimp cortical granules exhibited a particular pathway of maturation. The outer shape and inner organization considering different taxa suggested general as well as specific features of the development of cortical granules.

  11. Study on the genesis of Yishui banded iron formation (BIF) in the North China Craton: geochemical characteristics and tectonic environment

    NASA Astrophysics Data System (ADS)

    Moon, I.; Lee, I.; Yang, X.

    2015-12-01

    The Yishui BIFs are located in the Taishan Group, Shandong province of Eastern Block of North China Craton. The iron ore samples were collected from the mine pits. Major elements were analyzed by X-ray Fluoresence Spectromemter (XRF). Trace elements and REY (REE + Y) were analyzed by Inductively Coupled Plasma Mass Spectrometer (ICP-MS). Petrological, mineralogical and geochemical analyses of iron ores and their wall rock (amphibolite) were conducted to trace the genesis of Yishui BIF. Iron ores of Yishui BIF are mainly composed of SiO2 and Fe2O3T (SiO2+ Fe2O3T= 85.8 to 98.8 wt%) and consistent with major mineral components which are quartz and iron oxide such as magnetite and hematite. Low contents of TiO2 (0.01 to 0.09 wt%) , Al2O3 (0.42 to 1.18 wt%) and HFSE indicate no or little effect of detrital contamination. Iron ores have positive La, Eu, Gd, Er and Y anomalies with enriched HREE in PAAS normalized REY graph. The REY patterns of iron ores were used as a fingerprint to trace the source of iron and silica. Distinctive positive Eu anomalies (Eu/Eu*= 2.44-4.19), Y anomalies (Y/Y*=0.97 - 4.19), slightly negative Ce anomalies (Ce/Ce*= 0.87-0.97) and enriched HREE ((La/Yb)SN= 0.17-0.32) indicate that mixture of seawater and high-temperature hydrothermal fluid (>250 ◦C). Depositional environment in North China Craton implies that Yishui BIFs were formed at Neoarchean and associated arc-related tectonic setting. All these data suggest that Yishui BIFs belong to typical Algoma-type BIF.

  12. Neither dichotomies nor dualisms; simply genesis.

    PubMed

    Loredo-Narciandi, José C; Sánchez-González, José C

    2012-09-01

    Our starting point is an article by Uchoa Angela Branco published in 2009 in Integrative Psychological and Behavioral Sciences (vol. 43, pp. 350-355) and titled "Why Dichotomies can be Misleading while Dualities Fit the Analysis of Complex Phenomena". She criticizes the dualist uses of the distinction between subject and object, or between subjectivist and objectivist perspectives. However we subscribe to the criticism, we argue that some kind of distinction between objectual and subjectual realities is neccesary. Our argument is grounded on the classic constructivist Psychology, especially that of James Mark Baldwin's genetic logic. We assess two theoretical perspectives -the systemic and the structuralist ones- that, in our view, are at risk of falling into objectivism because they tend to reduce subjectual activity to objectivistic or formalistic kinds of explanation. Based on a critical recovery of some ideas of the French philosopher Michel Serres, we propose that subjects and objects must be understood as interpenetrated realities in perpetual construction.

  13. Petrology of igneous clasts in Northwest Africa 7034: Implications for the petrologic diversity of the martian crust

    NASA Astrophysics Data System (ADS)

    Santos, Alison R.; Agee, Carl B.; McCubbin, Francis M.; Shearer, Charles K.; Burger, Paul V.; Tartèse, Romain; Anand, Mahesh

    2015-05-01

    The martian meteorite Northwest Africa (NWA) 7034 was examined both petrographically and geochemically using several micro-beam techniques including electron probe microanalysis and secondary ion mass spectrometry. We have identified various clast types of igneous, sedimentary, and impact origin that occur within the breccia, and we define a classification scheme for these materials based on our observations, although our primary focus here is on the petrology of the igneous clasts. A number of different igneous clasts are present in this meteorite, and our study revealed the presence of at least four different igneous lithologies (basalt, basaltic andesite, trachyandesite, and an Fe, Ti, and P (FTP) rich lithology). These lithologies do not appear to be related by simple igneous processes such as fractional crystallization, indicating NWA 7034 is a polymict breccia that contains samples from several different igneous sources. The basalt lithologies are a good match for measured rock compositions from the martian surface, however more exotic lithologies (e.g., trachyandesite and FTP lithologies) show this meteorite contains previously unsampled rock types from Mars. These new rock types provide evidence for a much greater variety of igneous rocks within the martian crust than previously revealed by martian meteorites, and supports recent rover observations of lithologic diversity across the martian surface. Furthermore, the ancient ages for the lithologic components in NWA 7034 indicate Mars developed this lithologic diversity in the early stages of crust formation.

  14. An Impact Genesis for Loki Patera?

    NASA Technical Reports Server (NTRS)

    Thorsos, I. E.; Davies, A. G.

    2005-01-01

    What happens when a large impact event takes place on a satellite with a thin crust and lithosphere? In the early Solar System impact cratering and volcanism were the dominate processes shaping the surfaces of the terrestrial planets. Impact events may have triggered additional volcanism by uplifting partially molten mantle material to the surface, where it melts due to pressure release. Subsequently, the shattered crust may have provided pathways for magma to reach the surface creating a longer term hot spot. As the crusts of the terrestrial planets thickened, the ability of impacts to trigger volcanism diminished [1]. However, the highly-volcanic jovian satellite Io is located in a "high-impact" area of the Solar System [2], a victim of material attracted by Jupiter s gravitational field. In 1994 huge impacts were observed when fragments of comet Shoemaker- Levy 9 impacted Jupiter. The large icy satellites of Jupiter (Europa, Ganymede and Callisto) are pockmarked with many impact craters. Yet no impact features have been found on Io [3]. This is because of rapid resurfacing of Io due to volcanism, estimated at approx.1 cm/year [4] which over short geological time erases evidence of impacts. Io, however, has a lithosphere over a molten or partially-molten mantle [e.g., 5], and the effects of a sufficiently large impact may extend far beyond the evolution of the impact crater alone. At least one example of impact-triggered volcanism may exist in the Solar System today: the Loki Patera complex on Io.

  15. In search of a heating source for the generation of an anatectic complex: Peña Negra, Central Spain

    NASA Astrophysics Data System (ADS)

    Pereira, D.

    2003-04-01

    The Peña Negra complex in the north-central part of the Sierra de Gredos, Avila batholith, central Spain, provides a superb opportunity for the study of Variscan partial melting processes. The erosional level displayed may be considered to be that at which the Hercynian granites were produced. The protolith for the anatectic melts appears to have been the Schistogreywacke complex, together with the gneisses that were the main source for the Iberian granites (Pereira and Rodríguez-Alonso, 2000). However, the heat source for the anatexis remains controversial. The presence of basic rocks in the vicinity has given rise to the suggestion that mafic magmas of mantle origin may have been involved in the generation of the anatectic granites. Whilst data from experimental petrology may be used to support this concept, the volumes of mafic magma necessary for the anatexis appear improbably large. Geophysical models for Central Iberia do not support the presence of the requisite large basic complexes at depth. Furthermore radiometric dating of the scarce basic outcrops indicates that they are too old to have been involved in the granitic magma genesis. The alternative interpretation put forward here is that melting of the protolith was promoted by the radioactive decay of K, U and Th, elements that are present in relatively high concentrations in the supposed protolith rocks. Anatexis was enhanced by the presence of shear structures that permitted the concentration of volatiles as well as by existence of a fertile protolith. The situation is believed to have been analogous to that in other European Variscan terrains.

  16. Petrology of the Upper Border Series of the Skaergaard Intrusion

    NASA Astrophysics Data System (ADS)

    Salmonsen, L.; Tegner, C.; Jakobsen, J. K.

    2009-12-01

    Layered Series are similar in the early stages of differentiation until after FeTi-oxides appear as primocrysts. In the more evolved rocks the Upper Border Series is gradually enriched in SiO2, K2O and incompatible trace elements relative to the Layered Series as shown by Naslund (1984). This is expressed by abundant interstitial granophyre pockets between the cumulus crystals in the Upper Border Series. However, we find that it is possible to explain the Upper Border Series as a mixture of cumulus minerals and reasonable liquid estimates. Thus the Upper Border Series appears to trap a higher fraction of residual liquid than is the case in the Layered Series. We conclude that the Upper Border Series crystallized from the same liquid as the Layered Series and mainly differs in a high amount of trapped liquid. This implies that the Skaergaard chamber had only one convecting magma body. References: Naslund, H.R.; Petrology of the Upper Border Series of the Skaergaard Intrusion, Journal of Petrology, Vol. 25, Part 1, pp 185-212, 1984

  17. Petrological variability in recent magmatism at Axial Seamount

    NASA Astrophysics Data System (ADS)

    Dreyer, B. M.; Clague, D. A.; Gill, J. B.

    2011-12-01

    Axial Seamount is known for its compositional homogeneity. We report on petrological variability in lavas from the summit caldera and rims of Axial Seamount during the last ~1.2ka and its implications for shallow crustal magma dynamics. AUVs have mapped the summit at ~1 m resolution, and ROVs have collected numerous lavas and volcaniclastic cores. Geospatial, superpositional, compositional, and age constraint data were used to outline flow units and construct geologic maps. Nearly 200 glasses from summit lavas were analyzed for major elements. A subset of ~20 samples were analyzed for selected trace elements, Pb-, U-, and Th- isotope ratios, and 226Ra and 210Pb. The results a) confirm a high degree compositional homogeneity, b) demonstrate a more restricted range in Pb-isotope ratios than previous data, c) indicate uniform compositional source component(s) genetically linked to that of the Cobb-Eickelberg seamount chain, and d) expand the dataset of distinctly-low 230Th/232Th lavas and subdivide them into geospatial groups. Hundreds of volcaniclastic grains collected from subsurface depths of up to several tens of cm analyzed for major elements extend the record of summit magmatism beyond what is exposed. Summit lava glasses are compositionally N-MORB. Summit volcaniclastics range to higher MgO (+1%); thus, magmatism likely included more mafic episodes than is recorded in the flows as yet sampled or that volcaniclastics preferentially sample higher temperature lavas. Negative correlation of CaO/Al2O3 with MgO in all glasses suggests fractionation from parental melt(s) of plag ± ol but not cpx. K2O/TiO2 ranges are typical for much of the JdFR. Summit lavas range from aphyric to ~35% plag phyric ± a few % ol. Plag-phyric summit lavas tend to have greater MgO (>7.5%), lower CaO/Al2O3 (<0.80), and lower K2O/TiO2 (<0.10) compared to aphyric lavas. For ~18 caldera flows with absolute or relative age control, plag-phyric lavas are older than aphyric lavas, the oldest of

  18. Petrologic Regime Diagrams: Parameterizing Kinetic Controls on Vesiculation and Crystallization

    NASA Astrophysics Data System (ADS)

    Cashman, K. V.

    2014-12-01

    Regime diagrams are commonly employed in geophysical fluid dynamics to classify experimental results and, ideally, to define non-dimensional parameters that allow those results to be applied to natural systems. Petrologic experiments, in contrast, are typically run to mimic a specific natural system, and to infer conditions of magma storage, cooling or decompression. This approach has produced important insight into specific volcanoes, but the results are difficult to generalize. Additionally, very few experimental studies evaluate the vesiculation, crystallization and degassing histories of the same sample suite, an omission that is understandable given the time-consuming nature of the experiments and analysis, but which leaves important gaps in our general understanding of the interplay between gas exsolution, crystal formation and eruption dynamics. One way to bridge these gaps is to construct a regime diagram for conditions of vesiculation and crystallization. As both are controlled by the effective supercooling experienced by the magma during cooling or decompression, one key parameter is supersaturation, although in practice, decompression rate (cooling rate) are commonly used as proxies for supersaturation. Vesiculation and crystallization are also modulated by diffusion (dependent on individual species and melt viscosity), which can be simply approximated by melt composition. Using these parameters and published data for water-saturated decompression experiments, the following fields can be (partially) defined: (1) non-equilibrium volatile exsolution, (2) equilibrium volatile exsolution, and (3) exsolution accompanied by crystallization. Melt compositions, volatile contents and crystal textures of natural samples can be measured, and thus related (crudely) to the regime diagram. Additional information required for fully linking experiments and volcanic pyroclasts includes phase proportions (crystallization efficiency), pyroclast textures (phase change

  19. Asthenospheric diapir beneath the Baikal rift: Petrological constraints

    NASA Astrophysics Data System (ADS)

    Kiselev, A. I.; Popov, A. M.

    1992-07-01

    Presence of partially molten material at the base of the crust is one of the key elements in models advanced for the deep structure of the Baikal rift zone. This upper mantle anomaly can be interpreted either as a discontinuous 0-50 km thick layer, which is connected with the asthenosphere via narrow conduits (asthenolith, tensional failure model), or as a 200-300 km wide asthenospheric bulge which is in contact with the base of the crust (mantle plume model). Petrological data on mantle xenoliths from Cenozoic basalts do not agree with the simplistic model of complete mechanical replacement of the subrustal lithosphere by hot asthenospheric material. Spinel and garnet Iherzolite xenoliths represent lithospheric mantle material, derived from depths of 45-75 km; they display the compositional and thermal heterogeneity of the lithosphère which is related to its metasomatism and heating and also its cooling. It is suggested that in the area of the Baikal rift zone, tectonothermal activity of the lithosphère, reflecting its permeability, was caused by its extension in conjunction with the India-Eurasia collision. Lithospheric stretching induced decompression, partial melting and upwelling of the asthenosphere and intrusion of melts and fluids into the mantle lithosphère, and, perhaps, into the lower crust. Thus, the upper part of the asthenospheric bulge, which is characterized by low velocities at the Moho, low mantle densities and a highly uneven thermal field, probably corresponds to a zone of partially destroyed lithospheric mantle, that is impregnated with melts and fluids.

  20. Petrologic evidence for collisional heating of chondritic asteroids

    NASA Technical Reports Server (NTRS)

    Rubin, Alan E.

    1995-01-01

    The identification of the mechanism(s) responsible for heating asteroids is among the major problems in planetary science. Because of difficulties with models of electromagnetic induction and the decay of short-lived radionuclides, it is worthwhile to evaluate the evidence for collisional heating. New evidence for localized impact heating comes from the high proportion of relict type-6 material among impact-melt-bearing ordinary chondrites (OC). This relict material was probably metamorphosed by residual heat within large craters. Olivine aggregates composed of faceted crystals with 120 deg triple junctions occur within the melted regions of the Chico and Rose City OC melt rocks; the olivine aggregates formed from shocked, mosaicized olivine grains that underwent contact metamorphism. Large-scale collisional heating is supoorted by the correlation in OC between petrologic type and shock stage; no other heating mechanism can readily account for this correlation. The occurrence of impact-melt-rock clasts in OC that have been metamorphosed along with their whole rocks indicates that some impact events preceded or accompanied thermal metamorphism. Such impacts events, occurring during or shortly after accretion, are probably responsible for substantially melting approximately 0.5% of OC. These events must have heated a larger percentage of OC to subsolidus temperatures sufficient to have caused significant metamorphism. If collisional heating is viable, then OC parent asteroids must have been large; large OC asteroids in the main belt may include those of the S(IV) spectral subtype. Collisional heating is inconsistent with layered ('onion-shell') structures in OC asteroids (wherein the degree of metamorphism increases with depth), but the evidence for such structures is weak. It seems likely that collisional heating played an important role in metamorphosing chondritic asteroids.

  1. Early Petrologic Processes on the Ureilite Parent Body

    NASA Technical Reports Server (NTRS)

    Singletary, S. J.; Grove, T. L.

    2003-01-01

    We present a petrographic and petrologic analysis of 21 olivine-pigeonite ureilites, along with new experimental results on melt compositions predicted to be in equilibrium with ureilite compositions. We conclude that these ureilites are the residues of a partial melting/smelting event. Textural evidence preserved in olivine and pigeonite record the extent of primary smelting. In pigeonite cores, we observe fine trains of iron metal inclusions that formed by the reduction of olivine to pigeonite and metal during primary smelting. Olivine cores lack metal inclusions but the outer grain boundaries are variably reduced by a late-stage reduction event. The modal proportion of pigeonite and percentage of olivine affected by late stage reduction are inversely related and provide an estimation of the degree of primary smelting during ureilite petrogenesis. In our sample suite, this correlation holds for 16 of the 21 samples examined. Olivine-pigeonite-liquid phase equilibrium constraints are used to obtain temperature estimates for the ureilite samples examined. Inferred smelting temperatures range from approximately 1150 C to just over 1300 C and span the range of estimates published for ureilites containing two or more pyroxenes. Temperature is also positively correlated with modal percent pigeonite. Smelting temperature is inversely correlated with smelting depth--the hottest olivine-pigeonite ureilites coming from the shallowest depth in the ureilite parent body. The highest temperature samples also have oxygen isotopic signatures that fall toward the refractory inclusion-rich end of the carbonaceous chondrite-anhydrous mineral (CCAM) slope 1 mixing line. These temperature-depth variations in the ureilite parent body could have been created by a heterogeneous distribution of heat producing elements, which would indicate that isotopic heterogeneities existed in the material from which the ureilite parent body was assembled.

  2. Characterization and Petrological Constraints of the Midlithospheric Discontinuity

    NASA Astrophysics Data System (ADS)

    Rader, Erika; Emry, Erica; Schmerr, Nicholas; Frost, Daniel; Cheng, Cheng; Menard, Julie; Yu, Chun-Quan; Geist, Dennis

    2015-10-01

    Within continental lithosphere, widespread seismic evidence suggests a sharp discontinuous downward decrease in seismic velocity at 60-160 km depth. This midlithospheric discontinuity (MLD) may be due to anisotropy, melt, hydration, and/or mantle metasomatism. We survey global seismologic observations of the MLD, including observed depths, velocity contrasts, gradients, and locales across multiple seismic techniques. The MLD is primarily found in regions of thick continental lithosphere and is a decrease in seismic shear velocity (2-7% over 10-20 km) at 60-160 km depth, the majority of observations clustering at 80-100 km. Of xenoliths in online databases, 25% of amphibole-bearing xenoliths, 90% of phlogopite-bearing xenoliths, and none of carbonate-bearing xenoliths were formed at pressures associated with these depth (2-5 GPa). We used Perple_X modeling to evaluate the elastic moduli and densities of multiple petrologies to test if the MLD is a layer of crystallized melt. The fractional addition of 5-10% phlogopite, 10-15% carbonate, or 45-100% pyroxenite produce a 2-7% velocity decrease. We postulate this layer of crystallized melt would originate at active margins of continents and crystallize in place as the lithosphere cools. The concentration of mildly incompatible elements (Y, Ho, Er, Yb, and Lu) in xenoliths near the MLD is consistent with higher degrees of melting. Thus, we postulate that the MLD is the seismological signature of a chemical interface related to the paleointersection of a volatile-rich solidus and progressively cooling lithosphere. Furthermore, the MLD may represent a remnant chemical tracer of the lithosphere-asthenosphere boundary (LAB) from when the lithosphere was active and young.

  3. On the genesis of the Earth's magnetism.

    PubMed

    Roberts, Paul H; King, Eric M

    2013-09-01

    Few areas of geophysics are today progressing as rapidly as basic geomagnetism, which seeks to understand the origin of the Earth's magnetism. Data about the present geomagnetic field pours in from orbiting satellites, and supplements the ever growing body of information about the field in the remote past, derived from the magnetism of rocks. The first of the three parts of this review summarizes the available geomagnetic data and makes significant inferences about the large scale structure of the geomagnetic field at the surface of the Earth's electrically conducting fluid core, within which the field originates. In it, we recognize the first major obstacle to progress: because of the Earth's mantle, only the broad, slowly varying features of the magnetic field within the core can be directly observed. The second (and main) part of the review commences with the geodynamo hypothesis: the geomagnetic field is induced by core flow as a self-excited dynamo. Its electrodynamics define 'kinematic dynamo theory'. Key processes involving the motion of magnetic field lines, their diffusion through the conducting fluid, and their reconnection are described in detail. Four kinematic models are presented that are basic to a later section on successful dynamo experiments. The fluid dynamics of the core is considered next, the fluid being driven into motion by buoyancy created by the cooling of the Earth from its primordial state. The resulting flow is strongly affected by the rotation of the Earth and by the Lorentz force, which alters fluid motion by the interaction of the electric current and magnetic field. A section on 'magnetohydrodynamic (MHD) dynamo theory' is devoted to this rotating magnetoconvection. Theoretical treatment of the MHD responsible for geomagnetism culminates with numerical solutions of its governing equations. These simulations help overcome the first major obstacle to progress, but quickly meet the second: the dynamics of Earth's core are too complex

  4. Petrology of the Crystalline Rocks Hosting the Santa Fe Impact Structure

    NASA Technical Reports Server (NTRS)

    Schrader, C. M.; Cohen, B. A.

    2010-01-01

    We collected samples from within the area of shatter cone occurrence and for approximately 8 kilometers (map distance) along the roadway. Our primary goal is to date the impact. Our secondary goal is to use the petrology and Ar systematics to provide further insight into size and scale of the impact. Our approach is to: Conduct a detailed petrology study to identify lithologies that share petrologic characteristics and tectonic histories but with differing degrees of shock. Obtain micro-cores of K-bearing minerals from multiple samples for Ar-40/Ar-39 analysis. Examine the Ar diffusion patterns for multiple minerals in multiple shocked and control samples. This will help us to better understand outcrop and regional scale relationships among rocks and their responses to the impact event.

  5. Petrology and In Situ Trace Element Chemistry of a Suite of R Chondrites

    NASA Technical Reports Server (NTRS)

    Mittlefehldt, D. W.; Peng, Z. X.; Torrano, Z. A.

    2015-01-01

    Rumuruti (R) chondrites are characterized by low chondrule/matrix modal ratios, high oxidation state, small mean chondrule size, abundant sulfides and low metal contents, and are of petrologic types 3 to 6 [1, 2]. LAP 04840 (R5, [3]) and MIL 11207 (R6), contain the high-T hydrous phases amphibole and mica [3, 4]; not all equilibrated R chondrites contain these [2]. R chondrites thus can provide evidence on whether there are compositional effects caused by high-T, high-fluid metamorphism of nebular materials. We are investigating a suite of R chondrites of diverse petrologic grades to further understand the nature of the metamorphic processes that engendered them [5]. We report on our petrological studies, plus preliminary in situ analyses of trace elements in amphibole-bearing R chondrites.

  6. Mt. Nemrut volcano (Eastern Turkey): Temporal petrological evolution

    NASA Astrophysics Data System (ADS)

    Çubukçu, H. E.; Ulusoy, İ.; Aydar, E.; Ersoy, O.; Şen, E.; Gourgaud, A.; Guillou, H.

    2012-01-01

    Quaternary active Nemrut volcano is situated 12 km north of the Bitlis-Zagros suture zone, southern margin of continental collision between Arabian and Anatolian plates. The latest activity of the volcano dates back to historic times. Volcanic evolution of the volcano is investigated under two main stages: Pre-caldera and post-caldera separated by paroxysmal caldera forming eruptions not older than 90 ka. The majority of the products are silica oversaturated peralkaline {([Na 2O + K 2O]/Al 2O 3) > 1} felsic rocks with rare transitional-to-mildly alkaline basalts and mugearites. A compositional gap (Daly Gap) between 53% and 59% SiO 2 is partly filled with benmoreitic enclaves in peralkaline rhyolites. Benmoreitic enclaves display evidence of interminglement between mafic and felsic magmas. Observed mineral assemblages represent typical peralkaline mineralogy with aenigmatite, arfvedsonite-riebeckite, aegirine, fayalite and chevkinite. Geochemical evolution trends and modelling depict that protracted crystal fractionation dominated by feldspar, clinopyroxene, olivine and Fe-Ti oxides and crustal contamination would produce peralkaline rhyolites from the actual mafic compositions taken as parents. Mineralogical and petrographical observations indicate that the magma chamber is zoned compositionally having a crystal rich density layer between mafic and felsic melts. The genesis of Nemrut peralkaline magmatism has been ascribed to the ascension of slightly subduction modified asthenospheric melts into upper crustal high level reservoirs in localized extension in Muş ramp basin.

  7. Apollo 12 feldspathic basalts 12031, 12038 and 12072 - Petrology, comparison and interpretations

    NASA Technical Reports Server (NTRS)

    Beaty, D. W.; Hill, S. M. R.; Albee, A. L.; Baldridge, W. S.

    1979-01-01

    The paper presents the petrology of Apollo 12 feldspathic basalts. Modal and chemical data indicate that basalts 12072, 12038, and 12031 cannot be related to the other Apollo rock types; 12072 contains phenocrysts of olivine and pigeonite, 12038 is a multiply saturated equigranular basalt, and 12031 is a coarse-grained rock with granular to graphic intergrowths of pyroxene and plagioclase. The bulk compositions indicate that these basalts could not have been derived from the Apollo 12 olivine or ilmenite basalts by crystal-liquid fractionation, and their petrologic similarities suggest that they were produced in the same or similar source regions.

  8. The formation of chondrules: petrologic tests of the shock wave model.

    NASA Astrophysics Data System (ADS)

    Connolly, H. C., Jr.; Love, S. G.

    1998-04-01

    Chondrules are millimeter-sized rounded igneous rocks within chondritic meteorites. Their textures and fractionated mineral chemistries suggest that they formed by repeated, localized, brief (minutes to hours) melting of cold aggregates of mineral dust in the protoplanetary nebula. Astrophysical models of chondrule formation have been unable to explain the petrologically diverse nature of chondrites. However, a nebular shock wave model for chondrule formation agrees with many of the observed petrologic and geochemical properties of chondrules and shows how particles within the nebula are sorted by size and how rims around chondrules are formed. It also explains the volatile-rich nature of chondrule rims and the chondrite matrix.

  9. Mare basalt genesis - Modeling trace elements and isotopic ratios

    NASA Technical Reports Server (NTRS)

    Binder, A. B.

    1985-01-01

    Various types of mare basalt data have been synthesized, leading to the production of an internally consistent model of the mare basalt source region and mare basalt genesis. The model accounts for the mineralogical, major oxide, compatible siderophile trace element, incompatible trace element, and isotopic characteristics of most of the mare basalt units and of all the pyroclastic glass units for which reliable data are available. Initial tests of the model show that it also reproduces the mineralogy and incompatible trace element characteristics of the complementary highland anorthosite suite of rocks and, in a general way, those of the lunar granite suite of rocks.

  10. [Hypotheses for the genesis of cancer: a historical perspective].

    PubMed

    Morange, Michel

    2014-01-01

    The explanation of cancer has always been tightly related to the state of knowledge in biology, and its transformations. The present situation is not different. New techniques, such as deep sequencing, are rapidly moving our vision of cancer in an impredictable way. Systems biology, epigenetics, and the study of stem cells are generating new hypotheses on cancer and its evolution. New roles for aleatory events in the genesis of cancer have been proposed. In the traditional opposition between holism and reductionism, organisms and molecules, an intermediary level, the cancer cell, seems to be the most appropriate to study oncogenesis.

  11. [Effect of fenugreek on the growth of different genesis tumors].

    PubMed

    Zhilenko, V V; Zalietok, S P; Klenov, O O

    2012-01-01

    This paper deals with antitumor properties of a fenugreek (Trigonella Foenum Graecum L.) as to the different genesis tumors--the Ca755 mouse mammary carcinoma and the Guerin's carcinoma in rats. Fenugreek powder was shown to inhibit (25-40 %) growth of certain tumors, decrease (27-63%) level of malone dialdehyde in liver, heart and kidney. Consumption of fenugreek was accompanied with decreased polyamines (spermine, spermidine, putrescine) content in tumor tissue. Inclusion of fenugreek to allowance was shown to improve certain blood value.

  12. Phenomenological Theory of Isotropic-Genesis Nematic Elastomers

    NASA Astrophysics Data System (ADS)

    Lu, Bing-Sui; Ye, Fangfu; Xing, Xiangjun; Goldbart, Paul M.

    2012-06-01

    We consider the impact of the elastomer network on the nematic structure and fluctuations in isotropic-genesis nematic elastomers, via a phenomenological model that underscores the role of network compliance. The model contains a network-mediated nonlocal interaction as well as a new kind of random field that reflects the memory of the nematic order present at network formation and also encodes local anisotropy due to localized nematogenic polymers. This model enables us to predict regimes of short-ranged oscillatory spatial correlations (thermal and glassy) in the nematic alignment.

  13. Petrologic evolution of CM chondrites: The difficulty of discriminating between nebular and parent-body effects

    NASA Astrophysics Data System (ADS)

    Kerridge, J. F.; McSween, H. Y., Jr.; Bunch, T. E.

    1994-07-01

    We wish to draw attention to a major controversy that has arisen in the area of CM-chondrite petrology. The problem is important because its resolution will have profound implications for ideas concerning nebular dynamics, gas-solid interactions in the nebula, and accretionary processes in the nebula, among other issues. On the one hand, cogent arguments have been presented that 'accretionary dust mantles,' were formed in the solar nebula prior to accretion of the CM parent asteroid(s). On the other hand, no-less-powerful arguments have been advanced that a significant fraction of the CM lithology is secondary, produced by aqueous alteration in the near-surface regions of an asteroid-sized object. Because most, if not all, CM chondrites are breccias, these two views could coexist harmoniously, were it not for the fact that some of the coarse-grained lithologies surrounded by 'accretion dust mantles' are themselves of apparently secondary origin. Such an observation must clearly force a reassessment of one or both of the present schools of thought. Our objective here is to stimulate such a reassessment. Four possible resolutions of this conflict may be postulated. First, perhaps nature found a way of permitting such secondary alteration to take place in the nebula. Second, maybe dust mantles could form in a regolith, rather than a nebular, environment. Third, it is possible that dust mantles around secondary lithologies are different from those around primary lithologies. Finally, perhaps formation of CM chondrites involved a more complex sequence of events than visualized so far, so that some apparently 'primary' processes postdated certain 'secondary' processes.

  14. The petrology and geochemistry of a metabasite belt along the southern margin of Alaska.

    PubMed

    Bruand, E; Gasser, D; Bonnand, P; Stuewe, K

    2011-11-01

    A 600 km long metabasite belt is exposed at the southern border of the Chugach terrane in southern Alaska, south of the Eocene Chugach Metamorphic Complex (CMC). In this contribution, we present petrologic and geochemical results for parts of this metabasite belt. The metabasites studied are amphibolite grade and their PT conditions are evaluated with hornblende-plagioclase thermometry and the average PT method. From west to east the peak metamorphic conditions calculated are: about 730-793 °C for pressures between 5 and 15 kbar in the westernmost part, about 740-760 °C and 5 kbar in the middle locality and about 640-675 °C and 8 kbar in the easternmost locality. These results are comparable with the metamorphic conditions obtained on metapelite of the CMC for the westernmost and easternmost localities. In contrast, in the central part of the CMC, the metabasites experienced probably lower pressures than the metapelites to the north. Rare earth and trace element patterns of the metabasite belt are comparable with typical altered basalt patterns and reveal MORB and arc-tholeiitic geochemical characteristics. The presence of Ba and U anomalies are interpreted as a result of alteration prior to subduction, the Pb anomaly as a result of an intra-oceanic island arc signature and the Sr anomaly as a result of the interaction of sediments with the metabasites during subduction. We suggest that the association of MORB and arc tholeiitic rocks in the metabasite belt is likely derived from an intra-oceanic island arc which accreted to the Alaskan margin.

  15. Petrology of the Woods Mountains volcanic center, San Bernardino County, California

    SciTech Connect

    McCurry, M.O.

    1985-01-01

    The main purpose of this study is to investigate magma chamber processes through a petrological study of a large, newly examined silicic volcanic center. A characterization of the volcanic center was obtained through a combination of detailed mapping, petrography, analyses of bulk major and trace elements, and microprobe analyses of phenocryst phases. Cooperative studies were undertaken which included geophysical surveys of the center, Nd-Sm and Rb-Sr isotopic systematics and K-Ar dating of the rocks. The volcanic center began at 16.4 mybp with the incremental extrusion of ca 10 km/sup 3/ of dominantly mildly peraluminous dacitic and rhyolitic magma. At 15.5 mybp 870 km/sup 3/ of metaluminous to mildly peraluminous, dominantly rhyolitic pyroclastic flows were extruded, causing the formation of a 10 km diameter caldera. This was followed from 15.5 my to 14.8 my by the incremental, intracaldera extrusion of ca 10 km/sup 3/ of metaluminous to mildly peralkaline, high silica rhyolite magma. A model of magma chamber evolution is presented as follows: (1) a thermal pulse into the base of the crust initiated partial melting of a garnet-biotite gneiss at ca 17 mybp; (2) anatectic pockets of melt of dacitic composition intruded into the upper crust; (3) an increased flux of magma at 16 mybp resulted in the formation of a large magma chamber that evolved a cap of rhyolitic magma by a fractional crystallization within counter buoyant boundary layers; (4) a decay of input into the chamber occurred soon afterward, however chemical potential gradients induced by the rapid extrusion of a large part of the rhyolitic cupola resulted in strong volatile-complex diffusion, forming a thin cap of mildly peralkaline rhyolitic magma.

  16. Petrology and provenance of Upper Cretaceous Sandstone, southern San Rafael Mountains, Santa Barbara County, California

    SciTech Connect

    Toyne, C.D.

    1987-05-01

    Petrologic analysis of 24 medium to coarse-grained sandstone samples, collected from a 2950-m submarine fan complex of late Campanian-early Maestrichtian age exposed within Mono Creek Canyon, reveal commonly calcite cemented, poorly sorted, subangular biotic arkoses. Framework averages 86.0%. Matrix - primarily detrital quartz, feldspar, and lithic fragments finer than 0.03 mm and mechanically and chemically altered phyllosilicates and labile aphanites - averages 8.9%. Calcite cement averages 4.2%. Porosity averages 0.9%. Gazzi-Dickinson point counts of 400 framework grains per slide yield modal averages of Q/sub 37.7/ F/sub 49.8/ L/sub 12.5/; Qm/sub 27.4/ F/sub 49.8/ Lt/sub 22.8/; Qm/sub 35.6/ P/sub 43.7/ K/sub 20.7/; and Qp/sub 49.4/ Lv/sub 22.1/ Ls/sub 28.5/. P/F averages 0.68, Lv/L averages 0.45, Qp/Q averages 0.27, and detrital phyllosilicate, predominantly biotite, averages 5.7% of total framework. Neither primary nor secondary parameters vary systematically with stratigraphic position. Miscellaneous constituents average 1.3% of framework and include epidote, garnet, amphibole, pyroxene, zircon, and tourmaline as well as carbonaceous blebs, opaque minerals, and unidentifiable lithic fragments. Separate analysis of 100 medium sized quartz grains per slide indicates a mean population of 63.0% non-undulatory monocrystalline quartz, 9.1% undulatory monocrystalline quartz, 10.1% polycrystalline quartz of 2 to 3 crystals, and 17.9% polycrystalline quartz composed of more than 3 crystals. Modal data, plotted upon provenance discrimination diagrams, indicate a plutonic provenance transitional between a dissected magmatic arc and uplifted basement terrane. Paleocurrent data, neglecting possible clockwise rotation, indicate sediment transport from the north.

  17. Granulite facies lower crustal xenoliths from the Eifel, West Germany: petrological and geochemical aspects

    NASA Astrophysics Data System (ADS)

    Loock, G.; Stosch, H.-G.; Seck, H. A.

    1990-06-01

    Petrographic, petrological and geochemical data for 16 mafic meta-igneous, granulite facies lower crustal xenoliths from the East Eifel were collected in order to develop a model for the lower crustal history for this region. The xenoliths consist of plagioclase±amphibole±clinopyroxene±garnet±orthopyroxene±scapolite + opaque minerals±apatite±rutile±zircon. Garnet has reacted to a variable extent with plagioclase and clinopyroxene to form a corona of plagioclaseII+ amphibole + orthopyroxeneII. Pyroxenes and plagioclases show complex zoning patterns with regard to Al and Ca which can be interpreted in terms of P, T history. Decreasing temperature and pressure conditions are recorded by decreasing Al in clinopyroxene rims coexisting with increasing anorthite contents in plagioclase rims and the breakdown of garnet. In addition, a young heating event that affected the granulites to different degrees is inferred from the complementary Ca-zoning patterns in clino- and orthopyroxenes. Rare earth element (REE) patterns of whole rocks together with the trends displayed and fractionated liquids. REE analyses of the mineral separates display equilibrium partitioning patterns for amphibole and clinopyroxene, although isotopic data show that amphibole contains externally-derived Sr and Nd components not recognized in other minerals. At least a 4-stage history for the granulites is recorded: (1) intrusion and crystal fractionation of basaltic magmas in the lower crust, probably accompanied by crustal assimilation, (2) granulite facies metamorphism, (3) a decrease in temperature and pressure, and (4) a later heating event. The complicated thermal history is reflected in Sm-Nd mineral isochron ages which range from about 170 Ma down to about 100 Ma and cannot be assigned to distinct geological events. These ages correlate with inferred temperatures; the low ages are measured for xenoliths with the highest temperatures. In some cases the young heating event is likely to be

  18. The petrology and geochemistry of a metabasite belt along the southern margin of Alaska

    PubMed Central

    Bruand, E.; Gasser, D.; Bonnand, P.; Stuewe, K.

    2011-01-01

    A 600 km long metabasite belt is exposed at the southern border of the Chugach terrane in southern Alaska, south of the Eocene Chugach Metamorphic Complex (CMC). In this contribution, we present petrologic and geochemical results for parts of this metabasite belt. The metabasites studied are amphibolite grade and their PT conditions are evaluated with hornblende–plagioclase thermometry and the average PT method. From west to east the peak metamorphic conditions calculated are: about 730–793 °C for pressures between 5 and 15 kbar in the westernmost part, about 740–760 °C and 5 kbar in the middle locality and about 640–675 °C and 8 kbar in the easternmost locality. These results are comparable with the metamorphic conditions obtained on metapelite of the CMC for the westernmost and easternmost localities. In contrast, in the central part of the CMC, the metabasites experienced probably lower pressures than the metapelites to the north. Rare earth and trace element patterns of the metabasite belt are comparable with typical altered basalt patterns and reveal MORB and arc-tholeiitic geochemical characteristics. The presence of Ba and U anomalies are interpreted as a result of alteration prior to subduction, the Pb anomaly as a result of an intra-oceanic island arc signature and the Sr anomaly as a result of the interaction of sediments with the metabasites during subduction. We suggest that the association of MORB and arc tholeiitic rocks in the metabasite belt is likely derived from an intra-oceanic island arc which accreted to the Alaskan margin. PMID:26523072

  19. GENESYS 1990-91: Selected Program Evaluations. Publication Number 90.39.

    ERIC Educational Resources Information Center

    Wilkinson, David; Spano, Sedra G.

    GENESYS is a GENeric Evaluation SYStem for data collection and evaluation through computer technology. GENESYS gathers and reports the standard information (student characteristics, achievement, attendance, discipline, grades/credits, dropouts, and retainees) for specific groups of students. In the Austin (Texas) Independent School District's…

  20. Fabrication of Genesis Sample Simulants Using Plasma Source Ion Implantation (PSII)

    NASA Technical Reports Server (NTRS)

    Kuhlman, K. R.

    2002-01-01

    Plasma source ion implantation can be used to fabricate simulant samples for the Genesis mission. These simulants will be needed by investigators to validate sample preparation and analysis techniques for the returned Genesis samples. Additional information is contained in the original extended abstract.

  1. 76 FR 21403 - Notice of Availability of the Final Environmental Impact Statement for the Genesis Project...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-15

    ... Final Environmental Impact Statement (EIS) for the Newmont Mining Corporation's proposed Genesis Project...] Notice of Availability of the Final Environmental Impact Statement for the Genesis Project, Eureka County... addressed in the Draft EIS include: (1) The cumulative impacts of mining and related actions on...

  2. Petrology of enstatite chondrites and anomalous enstatite achondrites

    NASA Astrophysics Data System (ADS)

    van Niekerk, Deon

    2012-01-01

    . The broad importance of these studies lies in documenting the petrology of extraterrestrial materials that reveal the geological history of the young solar system prior to the existence of planets. Furthermore, they serve to identify which mineral assemblages record nebular processes and which record processes on asteroids, so that future studies may select the correct material to address particular questions.

  3. Formation of cratonic lithosphere: An integrated thermal and petrological model

    NASA Astrophysics Data System (ADS)

    Herzberg, Claude; Rudnick, Roberta

    2012-09-01

    The formation of cratonic mantle peridotite of Archean age is examined within the time frame of Earth's thermal history, and how it was expressed by temporal variations in magma and residue petrology. Peridotite residues that occupy the lithospheric mantle are rare owing to the effects of melt-rock reaction, metasomatism, and refertilization. Where they are identified, they are very similar to the predicted harzburgite residues of primary magmas of the dominant basalts in greenstone belts, which formed in a non-arc setting (referred to here as "non-arc basalts"). The compositions of these basalts indicate high temperatures of formation that are well-described by the thermal history model of Korenaga. In this model, peridotite residues of extensive ambient mantle melting had the highest Mg-numbers, lowest FeO contents, and lowest densities at ~ 2.5-3.5 Ga. These results are in good agreement with Re-Os ages of kimberlite-hosted cratonic mantle xenoliths and enclosed sulfides, and provide support for the hypothesis of Jordan that low densities of cratonic mantle are a measure of their high preservation potential. Cratonization of the Earth reached its zenith at ~ 2.5-3.5 Ga when ambient mantle was hot and extensive melting produced oceanic crust 30-45 km thick. However, there is a mass imbalance exhibited by the craton-wide distribution of harzburgite residues and the paucity of their complementary magmas that had compositions like the non-arc basalts. We suggest that the problem of the missing basaltic oceanic crust can be resolved by its hydration, cooling and partial transformation to eclogite, which caused foundering of the entire lithosphere. Some of the oceanic crust partially melted during foundering to produce continental crust composed of tonalite-trondhjemite-granodiorite (TTG). The remaining lithosphere gravitationally separated into 1) residual eclogite that continued its descent, and 2) buoyant harzburgite diapirs that rose to underplate cratonic nuclei

  4. On the Grand Challenges in Physical Petrology: the Multiphase Crossroads

    NASA Astrophysics Data System (ADS)

    Bergantz, G. W.

    2014-12-01

    Rapid progress in experimental, micro-analytical and textural analysis at the crystal scale has produced an unprecedented record of magmatic processes. However an obstacle to further progress is the lack of understanding of how mass, energy and momentum flux associated with crystal-rich, open-system events produces identifiable outcomes. Hence developing a physically-based understanding of magmatic systems linking micro-scale petrological observations with a physical template operating at the macro-scale presents a so-called "Grand Challenge." The essence of this challenge is that magmatic systems have characteristic length and feedback scales between those accessible by classical continuum and discrete methods. It has become increasingly obvious that the old-school continuum methods have limited resolution and power of explanation for multiphase (real) magma dynamics. This is, in part, because in crystal-rich systems the deformation is non-affine, and so the concept of constitutive behavior is less applicable and likely not even relevant, especially if one is interested in the emergent character of micro-scale processes. One expression of this is the cottage industry of proposing viscosity laws for magmas, which serves as "blunt force" de facto corrections for what is intrinsically multiphase behavior. Even in more fluid-rich systems many of these laws are not suitable for use in the very transport theories they aim to support. The alternative approach is the discrete method, where multiphase interactions are explicitly resolved. This is a daunting prospect given the numbers of crystals in magmas. But perhaps all crystals don't need to be modeled. I will demonstrate how discrete methods can recover critical state behavior, resolve crystal migration, the onset of visco-elastic behavior such as melt-present shear bands which sets the large-scale mixing volumes, some of the general morpho-dynamics that underlies purported rheological models, and transient controls on

  5. Cryosols of the Northeast Siberian Lena River Delta and its hinterland - genesis and diversity

    NASA Astrophysics Data System (ADS)

    Zubrzycki, Sebastian; Kutzbach, Lars; Pfeiffer, Eva-Maria

    2016-04-01

    The North-Siberian Lena River Delta (LRD) is the largest Arctic delta and an important interface between the Arctic Ocean in the North and the large Siberian land masses in the South. LRD consists not only of Holocene deltaic sediment deposits as a river terrace and the modern active floodplains but also of remnants of the former Pleistocene mainland including large islands of ice-complex sediments and the Arga-Muora-Sise Island, which is composed of pure sand sediments of still debated origin. The highly diverse landscape structure of LRD is reflected by a great variety of permafrost-affected soils (cryosols). This study aims at describing this great cryosol diversity and at analysing the dominant soil-forming processes in this comparatively scarcely studied soil region. The soil development in the investigated continuous permafrost region is limited by the short thawing period of around three months (June to September) and takes place in the shallow (below 1 m) seasonally thawed active layer. The geological parent material plays an important role for the development of soils in the LRD region. The distribution of the various soil types closely follows the pattern of the geomorphic units characterised by differing sedimentation conditions. The properties and genesis of the soils on the Holocene river terrace and the modern floodplains are strongly affected by the enormous amounts of fluvial sediments (about 12 x 106 tons per year) brought by the Lena River into its delta. The fluvial sedimentation together with the also pronounced aeolian sedimentation results in a fast vertical growth of soils. The upward rise of the soil surface leads to an upward movement of the permafrost table resulting in fast incorporation of soil material formed in the supra-permafrost zone into the permafrost. Due to the morphodynamics of ice-wedge polygons and resulting formation of patterned ground with elevated rims and depressed and water-saturated centres, the Holocene river terrace

  6. Examples of Optical Assessment of Surface Cleanliness of Genesis Samples

    NASA Technical Reports Server (NTRS)

    Rodriquez, Melissa C.; Allton, J. H.; Burkett, P. J.; Gonzalez, C. P.

    2013-01-01

    Optical microscope assessment of Genesis solar wind collector surfaces is a coordinated part of the effort to obtain an assessed clean subset of flown wafer material for the scientific community. Microscopic survey is typically done at 50X magnification at selected approximately 1 square millimeter areas on the fragment surface. This survey is performed each time a principle investigator (PI) returns a sample to JSC for documentation as part of the established cleaning plan. The cleaning plan encompasses sample handling and analysis by Genesis science team members, and optical survey is done at each step in the process. Sample surface cleaning is performed at JSC (ultrapure water [1] and UV ozone cleaning [2]) and experimentally by other science team members (acid etch [3], acetate replica peels [4], CO2 snow [5], etc.). The documentation of each cleaning method can potentially be assessed with optical observation utilizing Image Pro Plus software [6]. Differences in particle counts can be studied and discussed within analysis groups. Approximately 25 samples have been identified as part of the cleaning matrix effort to date.

  7. The Genesis of Chua's Circuit:. Connecting Science, Art and Creativity

    NASA Astrophysics Data System (ADS)

    Bertacchini, Francesca; Bilotta, Eleonora; Laria, Giuseppe; Pantano, Pietro

    2013-01-01

    The Chua's circuit has provided science with a real scientific and technological advancement in the field of dynamical systems. But the origin of the Chua's circuit, which has resulted in major areas of study within Chaos Theory, with thousands of printed scientific articles, is not widely known. In this chapter, we trace the fundamental stages of the Genesis of the Chua's circuit. To make the story more appealing for the new generations, a 3D movie was made (issued on DVD, with this volume). Besides presenting the main characters from the history of such system, it also introduces Lorenz, Poincare, Julia and Cantor as the precursors of the studies on chaos, which discuss the need for a physical system that demonstrates chaos, a phenomenon not yet understood, in a numerical, physical and experimental way. The story, enriched by the conversations of the above mentioned characters, was staged exactly as it occurred, derived from Professor Chua's famous article of 1983, The Genesis of the Chua's circuit. And the story continues with the authors contribution in expanding Chaos Theory, with the discovery of almost one thousand attractors, which have provided new important elements for the advancement of science in the field of nonlinear chaotic systems.

  8. Nano-inclusions in diamond: Evidence of diamond genesis

    NASA Astrophysics Data System (ADS)

    Wirth, R.

    2015-12-01

    The use of Focused Ion Beam technology (FIB) for TEM sample preparation introduced approximately 15 years ago revolutionized the application of TEM in Geosciences. For the first time, FIB enabled cutting samples for TEM use from exactly the location we are interested in. Applied to diamond investigation, this technique revealed the presence of nanometre-sized inclusions in diamond that have been simply unknown before. Nanoinclusions in diamond from different location and origin such as diamonds from the Lower and Upper Mantle, metamorphic diamonds (Kazakhstan, Erzgebirge, Bohemia), diamonds from ophiolites (Tibet, Mongolia, Xinjiang, Ural Mountains), diamonds from igneous rocks (Hawaii, Kamchatka) and impact diamonds (Popigai Crater, Siberia) have been investigated during the last 15 years. The major conclusion of all these TEM studies is, that the nanoinclusions, their phases and phase composition together with the micro- and nanostructure evidence the origin of diamond and genesis of diamond. We can discriminate Five different mechanisms of diamond genesis in nature are observed: Diamond crystallized from a high-density fluid (Upper mantle and metamorphic diamond). Diamond crystallized from carbonatitic melt (Lower mantle diamond). Diamond precipitates from a metal alloy melt (Diamond from ophiolites). Diamond crystallized by gas phase condensation or chemical vapour condensation (CVD) (Lavas from Kamchatka, xenoliths in Hawaiian lavas). Direct transformation of graphite into diamond.

  9. Laser Subdivision of the Genesis Concentrator Target Sample 60000

    NASA Technical Reports Server (NTRS)

    Lauer, Howard V., Jr.; Burkett, P. J.; Rodriquez, M. C.; Nakamura-Messenger, K.; Clemett, S. J.; Gonzales, C. P.; Allton, J. H.; McNamara, K. M.; See, T. H.

    2013-01-01

    The Genesis Allocation Committee received a request for 1 square centimeter of the diamond-like-carbon (DLC) concentrator target for the analysis of solar wind nitrogen isotopes. The target consists of a single crystal float zone (FZ) silicon substrate having a thickness on the order of 550 micrometers with a 1.5-3.0 micrometer-thick coating of DLC on the exposed surface. The solar wind is implanted shallowly in the front side DLC. The original target was a circular quadrant with a radius of 3.1 cm; however, the piece did not survive intact when the spacecraft suffered an anomalous landing upon returning to Earth on September 8, 2004. An estimated 75% of the DLC target was recovered in at least 18 fragments. The largest fragment, Genesis sample 60000, has been designated for this allocation and is the first sample to be subdivided using our laser scribing system Laser subdivision has associated risks including thermal diffusion of the implant if heating occurs and unintended breakage during cleavage. A careful detailed study and considerable subdividing practice using non-flight FZ diamond on silicon, DOS, wafers has considerably reduced the risk of unplanned breakage during the cleaving process. In addition, backside scribing reduces the risk of possible thermal excursions affecting the implanted solar wind, implanted shallowly in the front side DLC.

  10. Genesis of transverse kame trains in eastern Poland

    NASA Astrophysics Data System (ADS)

    Terpiłowski, Sławomir

    2007-01-01

    Transverse kames, forming trains perpendicular to the direction of ice-sheet advance, are rare morphological elements in previously glaciated areas. The genesis of an example from the ice-contact zone of the Wartanian glaciation in eastern Poland is discussed. The transverse kames there form two main, distinctly separated, sub-parallel trains. Their sedimentary successions fill erosional troughs incised in the pre-Wartanian deposits on northern slopes. They consist of thick glaciofluvial sand and glaciofluvial/glaciolacustrine sandy/silty units that are covered with a thin, usually discontinuous, glacial till succession. The genesis of this kame type has been modelled. It is concluded that transverse kames developed in two phases: (1) erosion of the substratum in subglacial channels during initial deglaciation, and (2) glaciofluvial deposition in crevasses during advanced deglaciation (in the form of low-energy fans periodically submerged under stagnant water), followed locally by a cover of flowtills. Both the ablation of the ice and the accumulation of the kame deposits were controlled by the co-occurrence of ice zones either enriched or impoverished with sediment. Zonal enrichment of ice with debris was determined by the development of shear zones over substratum elevations that were inclined up-ice. The formation and subsequent infilling of crevasses both took place in zones of relatively clean ice, so that the resulting kames form a train perpendicular to the direction of ice movement.

  11. Aetiological factors in the genesis of pregnancy hydronephrosis.

    PubMed

    Au, K K; Woo, J S; Tang, L C; Liang, S T

    1985-11-01

    In order to identify possible aetiological factors in the genesis of physiological hydronephrosis in pregnancy, the degree of pelvic-calyceal dilatation in 90 asymptomatic pregnant women was correlated with levels of plasma oestradiol, progesterone, 24-hour urinary oestriol, the site of the placenta, birthweight of the fetus, and pelvic inlet measurements. A grading system based on maximum calyceal diameter was used; 90% of the patients were found to have at least mild dilatation on the right side. No correlation was demonstrated between the degree of hydronephrosis and the levels of oestradiol, progesterone and 24-hour urinary oestriol excretion. The birth-weight of the fetus and its relationship with the pelvic inlet measurements also did not correlate with the occurrence of hydronephrotic changes in the kidneys. The only significant positive finding was a higher incidence of moderate and severe hydronephrosis occurring in patients with a right-sided placenta than compared with the left (x2 = 4.77; p less than 0.05), although the sensitivity and specificity in predicting hydronephrosis from a right-sided placenta is low (53% and 66% respectively). Our results support the hypothesis of a mechanical aetiology in the genesis of pregnancy hydronephrosis, where vascular compression on the ureters may be an important contributory factor. Our study has also shown that urinary tract infection and reduction of creatinine clearance were not more common in patients with moderate or severe pelvic-calyceal dilatation.

  12. Running reduces stress and enhances cell genesis in aged mice.

    PubMed

    Kannangara, Timal S; Lucero, Melanie J; Gil-Mohapel, Joana; Drapala, Robert J; Simpson, Jessica M; Christie, Brian R; van Praag, Henriette

    2011-12-01

    Cell proliferation and neurogenesis are diminished in the aging mouse dentate gyrus. However, it is not known whether isolated or social living affects cell genesis and stress levels in old animals. To address this question, aged (17-18 months old) female C57Bl/6 mice were single or group housed, under sedentary or running conditions. We demonstrate that both individual and socially housed aged C57Bl/6 mice have comparable basal cell proliferation levels and demonstrate increased running-induced cell genesis. To assess stress levels in young and aged mice, corticosterone (CORT) was measured at the onset of the active/dark cycle and 4h later. In young mice, no differences in CORT levels were observed as a result of physical activity or housing conditions. However, a significant increase in stress in socially housed, aged sedentary animals was observed at the onset of the dark cycle; CORT returned to basal levels 4h later. Together, these results indicate that voluntary exercise reduces stress in group housed aged animals and enhances hippocampal cell proliferation.

  13. The connection between crustal reworking and petrological diversity in the deep crust: clues from migmatites

    NASA Astrophysics Data System (ADS)

    Carvalho, Bruna B.; Sawyer, Edward W.; de Assis Janasi, Valdecir

    2016-04-01

    The deep levels of the continental crust have been extensively reworked as result of crustal differentiation. Migmatites are widespread in these high-grade metamorphic terrains, and provide valuable information on how processes such as partial melting, segregation of the melt from the residue and subsequent chemical exchanges lead to the petrological diversity found in the deep crust. This study investigates processes that transformed a largely uniform, metagranodiorite protolith into a very complex migmatite that contains three varieties of diatexites (grey, schlieren and homogenous diatexites) and several types of leucosomes. The Kinawa Migmatite is part of the Archean TTG crust in the São Francisco Craton (Brazil), which has been reworked in a shear zone environment at upper amphibolite facies conditions (<730°C and 5-6 kbar); thus it may be typical of crustal reworking in the interior of old cratons [1]. Grey diatexites are residual rocks formed by the extraction of a water-fluxed melt created via the reaction Pl + Kfs + Qz + H2O = melt. Diversity within the grey diatexites arises from different degrees of melt segregation (maximum ~40% melt). Schlieren diatexites are very heterogeneous rocks in which residuum-rich domains alternate with leucocratic quartzo-feldspathic domains where melt accumulated. Homogeneous diatexites are coarse-grained leucocratic rocks and represent larger bodies of anatectic melt with minor amounts (<20%) of entrained residuum. Leucosomes display a wide range of compositions from tonalitic to alkali-feldspar granite. Leucosomes, homogeneous diatexites and the quartzo-feldspathic domains in the schlieren diatexites all show a sequence of microstructural stages from plagioclase-dominated to K-feldspar-dominated frameworks many of which show evidence for tectonic compaction. Thus, further segregation of melt from solids occurred during crystallization. Minor amphibolite dykes in the metagranodiorite did not melt. They occur as angular to

  14. 75 FR 69458 - Notice of Availability of the Record of Decision for the Genesis Solar Energy Project and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-12

    ... Bureau of Land Management Notice of Availability of the Record of Decision for the Genesis Solar Energy... Genesis Solar Energy Project (GSEP). The GSEP is a concentrated solar electrical generating facility using...-mail: CAPSSolarNextEraFPL@blm.gov . SUPPLEMENTARY INFORMATION: Genesis Solar, LLC, a wholly...

  15. Petrology and Geochemistry of Lunar Meteorite Abar al'Uj 012

    NASA Astrophysics Data System (ADS)

    Mészáros, M.; Hofmann, B. A.; Korotev, R. L.; Gnos, E.; Greber, N.; Greenwood, R. C.

    2014-09-01

    The petrology and geochemistry of Abar al’Uj 012, a feldspathic lunar meteorite found in Saudi Arabia is described. The meteorite is a vesicular crystalline impact-melt breccia, which lacks a fusion crust and has a ferroan anorthosite affinity.

  16. Hardgrove grindability index and petrology used as an enhanced predictor of coal feed rate

    SciTech Connect

    Hower, J.C. )

    1990-01-01

    An improved predictor of coal pulverization behavior and coal feed rate is under development at the CAER based upon the interaction between Hardgrove Grindability Index (HGI) and coal petrology. With educated attention, this interaction may be a useful tool to enhance coal feed rates if cautiously extended to the mining environment where blends of coal lithotypes are produced.

  17. Unmixing the SNCs: Chemical, Isotopic, and Petrologic Components of the Martian Meteorites

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This volume contains abstracts that have been accepted for presentation at the conference on Unmixing the SNCs: Chemical, Isotopic, and Petrologic Components of Martian Meteorites, September 11-12, 2002, in Houston, Texas. Administration and publications support for this meeting were provided by the staff of the Publications and Program Services Department at the Lunar and Planetary Institute.

  18. Eruptive stratigraphy of the Tatara-San Pedro complex, 36°S, sourthern volcanic zone, Chilean Andes: reconstruction method and implications for magma evolution at long-lived arc volcanic centers

    USGS Publications Warehouse

    Dungan, M.A.; Wulff, A.; Thompson, R.

    2001-01-01

    The Quaternary Tatara-San Pedro volcanic complex (36°S, Chilean Andes) comprises eight or more unconformity-bound volcanic sequences, representing variably preserved erosional remnants of volcanic centers generated during 930 ky of activity. The internal eruptive histories of several dominantly mafic to intermediate sequences have been reconstructed, on the basis of correlations of whole-rock major and trace element chemistry of flows between multiple sampled sections, but with critical contributions from photogrammetric, geochronologic, and paleomagnetic data. Many groups of flows representing discrete eruptive events define internal variation trends that reflect extrusion of heterogeneous or rapidly evolving magna batches from conduit-reservoir systems in which open-system processes typically played a large role. Long-term progressive evolution trends are extremely rare and the magma compositions of successive eruptive events rarely lie on precisely the same differentiation trend, even where they have evolved from similar parent magmas by similar processes. These observations are not consistent with magma differentiation in large long-lived reservoirs, but they may be accommodated by diverse interactions between newly arrived magma inputs and multiple resident pockets of evolved magma and / or crystal mush residing in conduit-dominated subvolcanic reservoirs. Without constraints provided by the reconstructed stratigraphic relations, the framework for petrologic modeling would be far different. A well-established eruptive stratigraphy may provide independent constraints on the petrologic processes involved in magma evolution-simply on the basis of the specific order in which diverse, broadly cogenetic magmas have been erupted. The Tatara-San Pedro complex includes lavas ranging from primitive basalt to high-SiO2 rhyolite, and although the dominant erupted magma type was basaltic andesite ( 52-55 wt % SiO2) each sequence is characterized by unique proportions of

  19. Genesis Concentrator Target Particle Contamination Mapping and Material Identification

    NASA Technical Reports Server (NTRS)

    Calaway, Michael J.; Rodriquez, M. C.; Allton, J. H.

    2007-01-01

    The majority of surface particles were found to be < 5 microns in diameter with increasing numbers close to the optical resolution limit of 0.3 microns. Acceleration grid EDS results show that the majority of materials appear to be from the SRC shell and SLA materials which include carbon-carbon fibers and Si-rich microspheres in a possible silicone binder. Other major debris material from the SRC included white paint, kapton, collector array fragments, and Al. Image analysis also revealed that SRC materials were also found mixed with the Utah mud and salt deposits. The EDS analysis of the acceleration grid showed that particles < 1 m where generally carbon based particles. Chemical cleaning techniques with Xylene and HF in an ultrasonic bath are currently being investigated for removal of small particles by the Genesis science team as well as ultra-pure water megasonic cleaning by the JSC team [4]. Removal of organic contamination from target materials is also being investigated by the science team with the use of UV-ozone cleaning devices at JSC and Open University [5]. In preparation for solar wind oxygen analyses at UCLA and Open University [1, 2], surface particle contamination on three Genesis concentrator targets was closely examined to evaluate cleaning strategies. Two silicon carbide (Genesis sample # 60001 and 60003) and one chemical vapor deposited (CVD) 13C concentrator target (60002) were imaged and mosaic mapped with optical microscopes. The resulting full target mosaic images and particle feature maps were subsequently compared with non-flight, but flight-like, concentrator targets and sample return capsule (SRC) materials. Contamination found on the flown concentrator acceleration grid was further examined using a scanning electron microscope (SEM). Energy dispersive X-ray spectroscopy (EDS) for particle identification was subsequently compared with the optical images from the flown targets. Figure 1 show that all three targets imaged in this report

  20. Bases of the Mantle-Carbonatite Conception of Diamond Genesis

    NASA Astrophysics Data System (ADS)

    Litvin, Yuriy; Spivak, Anna; Kuzyura, Anastasia

    2016-04-01

    In the mantle-carbonatite conception of diamond genesis, the results of physic-chemical experiments are coordinated with the data of analytic mineralogy of primary inclusions in natural diamonds. Generalization of the solutions of principal genetic problems constitutes the bases of the conception. The solutions are following: (1) it is grounded that diamond-parental melts of the upper mantle have peridotite/eclogite - carbonatite - carbon compositions, of the transition zone - (wadsleite↔ringwoodite) - majorite - stishovite - carbonatite - carbon compositions, and of the lower mantle - periclase/wustite - bridgmanite - Ca-perovskite -stishovite - carbonatite - carbon compositions; (2) a construction of generalized diagrams for the diamond-parental media, which reveal changeable compositions of the growth melts of diamonds and associated phases, their genetic relations to the mantle substance, and classification connections of the primary inclusions in natural diamonds; (3) experimental equilibrium phase diagrams of syngenesis of diamonds and primary inclusions, which characterize the nucleation and growth conditions of diamonds and a capture of paragenetic and xenogenetic minerals by the growing diamonds; (4) a determination of the phase diagrams of diamonds and inclusions syngenesis under the regime of fractional crystallization, which discover the regularities of ultrabasic-basic evolution and paragenesis transitions in the diamond-forming systems of the upper and lower mantle. The evidence of the physic-chemically united mode of diamond genesis at the mantle depths with different mineralogy is obtained. References. Litvin Yu.A. (2007). High-pressure mineralogy of diamond genesis. In: Advances in High-Pressure Mineralogy (edited by Eiji Ohtani), Geological Society of America Special paper 421, 83-103. Litvin Yu.A. (2012). Experimental study of physic-chemical conditions of natural diamond formation on an example of the eclogite

  1. Data-driven Science in Geochemistry & Petrology: Vision & Reality

    NASA Astrophysics Data System (ADS)

    Lehnert, K. A.; Ghiorso, M. S.; Spear, F. S.

    2013-12-01

    measurements, experiments, and models, both from past and from present studies, and their poor discoverability, interoperability, and standardization. Other deficiencies include the lack of widespread sample curation and online sample catalogs, and broad community support and enforcement of open data sharing policies and a strategy for sustained funding and operation of the cyberinfrastructure. In order to achieve true data-driven science in geochemistry and petrology, one of the primary requirements is to change the way data and models are managed and shared to dramatically improve their access and re-usability. Adoption of new data publication practices, new ways of citing data that ensure attribution and credit to authors, tools that help investigators to seamlessly manage their data throughout the data life cycle, from the point of acquisition to upload to repositories, and population of databases with historical data are among the most urgent needs. The community, especially early career scientists, must work together to produce the cultural shift within the discipline toward sharing of data and knowledge, virtual collaboration, and social networking. Dziewonski, A M, & Anderson, D L: Physics of the Earth and Planet Interiors 25 (4), 297 (1981) Hey, T, Tansley, S, Tolle, K (Eds.): Redmond, VA: Microsoft Research (2009) Zindler, A, & Hart, S R: Ann. Rev. Earth Plan. Sci. 14, 493 (1986)

  2. Genesis Solar Wind Sample Curation: A Progress Report

    NASA Technical Reports Server (NTRS)

    Allton, Judith H.; Calaway, M. J.; Rodriquez, M. C.; Hittle, J. D.; Wentworth, S. J.; Stansbery, E. K.; McNamara, K. M.

    2006-01-01

    In the year since the Genesis solar wind collector fragments were returned, early science samples, specimens for cleaning experiments, and science allocations have been distributed. Solar wind samples are stored under nitrogen and handled in an ISO Class 4 (Class 10) laboratory. For array collector fragments, a basic characterization process has been established. This characterization consists of identification of solar wind regime, whole fragment image for identification and surface quality, higher magnification images for contaminant particle density, and assessment of molecular film contaminant thickness via ellipsometry modeling. Compilations of this characterization data for AuOS (gold film on sapphire), and sapphire from the bulk solar wind for fragments greater than 2 cm are available. Removal of contaminant particles using flowing ultrapure water (UPW) energized megasonically is provided as requested.

  3. On the genesis of the idiotypic network theory.

    PubMed

    Civello, Andrea

    2013-01-01

    The idiotypic network theory (INT) was conceived by the Danish immunologist Niels Kaj Jerne in 1973/1974. It proposes an overall view of the immune system as a network of lymphocytes and antibodies. The paper tries to offer a reconstruction of the genesis of the theory, now generally discarded and of mostly historical interest, first of all, by taking into account the context in which Jerne's theoretical proposal was advanced. It is argued the theory challenged, in a sense, the supremacy of the clonal selection theory (CST), this being regarded as the predominant paradigm in the immunological scenario. As CST found shortcomings in explaining certain phenomena, anomalies, one could view INT as a competing paradigm claiming to be able to make sense of such phenomena in its own conceptual framework. After a summary outline of the historical background and some relevant terminological elucidations, a narrative of the various phases of elaboration of the theory is proposed, up to its official public presentation.

  4. Kuhn and the genesis of the "new historiography of science".

    PubMed

    de Oliveira, J C Pinto

    2012-03-01

    In this paper I identify a tension between the two sets of works by Kuhn regarding the genesis of the "new historiography of science". In the first, it could be said that the change from the traditional to the new historiography is strictly endogenous (referring to internal causes or reasons). In the second, the change is predominantly exogenous. To address this question, I draw on a text that is considered to be less important among Kuhn's works, but which, as shall be argued, allows some contact between Kuhn's two approaches via Koyré. I seek to point out and differentiate the roles of Koyré and Kuhn--from Kuhn's point of view--in the development of the historiography of science and, as a complement, present some reflections regarding the justification of the new historiography.

  5. On gravitational chirality as the genesis of astrophysical jets

    NASA Astrophysics Data System (ADS)

    Tucker, R. W.; Walton, T. J.

    2017-02-01

    It has been suggested that single and double jets observed emanating from certain astrophysical objects may have a purely gravitational origin. We discuss new classes of plane-fronted and pulsed gravitational wave solutions to the equation for perturbations of Ricci-flat spacetimes around Minkowski metrics, as models for the genesis of such phenomena. These solutions are classified in terms of their chirality and generate a family of non-stationary spacetime metrics. Particular members of these families are used as backgrounds in analysing time-like solutions to the geodesic equation for test particles. They are found numerically to exhibit both single and double jet-like features with dimensionless aspect ratios suggesting that it may be profitable to include such backgrounds in simulations of astrophysical jet dynamics from rotating accretion discs involving electromagnetic fields.

  6. Genesis of Atlantic Lows Experiment (GALE) - An overview

    NASA Technical Reports Server (NTRS)

    Dirks, R. A.; Kuettner, J. P.; Moore, J. A.

    1988-01-01

    The field phase of the Genesis of Atlantic Lows Experiment (GALE) was conducted from 15 January to 15 March 1986. The objectives of GALE were to study mesoscale and air-sea interaction processes in East Coast winter storms, with particular emphasis on their contributions to cyclogenesis. This project area, specail observing systems, and field operations are described. There were thirteen special observing periods during the field phase including eight cases of cyclogenesis. Meterological and oceanographic phenomena on which special observations were collected include: cyclogenesis, rainbands, cold fronts, coastal fronts, cold-air damming, jets streaks, tropopause folding, low-level jets, cold-air outbreaks, lightning and marine boundary layer interactions with Gulf Stream and mid-shelf oceanic fronts. Preliminary research findings and operational implications are presented. GALE data documents are listed. The GALE data set is open to all interested scientists.

  7. Genesis of Atlantic Lows Experiment (GALE): An Overview.

    NASA Astrophysics Data System (ADS)

    Dirks, R. A.; Kuettner, J. P.; Moore, J. A.

    1988-02-01

    The field phase of the Genesis of Atlantic Lows Experiment (GALE) was conducted from 15 January to 15 March 1986. The objectives of GALE were to study mesoscale and air-sea interaction processes in East Coast winter storms, with particular emphasis on their contributions to cyclogenesis. The project area, special observing systems, and field operations are described. There were thirteen special observing periods during the field phase including eight cases of cyclogenesis. Meteorological and oceanographic phenomena on which special observations were collected include: cyclogenesis, rainbands, cold fronts, coastal fronts, cold-air damming, jet streaks, tropopause folding, low-level jets, cold-air outbreaks, lightning and marine boundary layer interactions with Gulf Stream and mid-shelf oceanic fronts. Preliminary research findings and operational implications are presented. GALE data documents are listed. The GALE data set is open to all interested scientists.

  8. GENESI-DR Portal: a scientific gateway to distributed repositories

    NASA Astrophysics Data System (ADS)

    Goncalves, Pedro; Brito, Fabrice; D'Andria, Fabio; Cossu, Roberto; Fusco, Luigi

    2010-05-01

    GENESI-DR (Ground European Network for Earth Science Interoperations - Digital Repositories) is a European Commission (EC)-funded project, kicked-off early 2008 lead by ESA; partners include Space Agencies (DLR, ASI, CNES), both space and no-space data providers such as ENEA (I), Infoterra (UK), K-SAT (N), NILU (N), JRC (EU) and industry as Elsag Datamat (I), CS (F) and TERRADUE (I). GENESI-DR intends to meet the challenge of facilitating "time to science" from different Earth Science disciplines in discovery, access and use (combining, integrating, processing, …) of historical and recent Earth-related data from space, airborne and in-situ sensors, which are archived in large distributed repositories. "Discovering" which data are available on a "geospatial web" is one of the main challenges ES scientists have to face today. Some well- known data sets are referred to in many places, available from many sources. For core information with a common purpose many copies are distributed, e.g., VMap0, Landsat, and SRTM. Other data sets in low or local demand may only be found in a few places and niche communities. Relevant services, results of analysis, applications and tools are accessible in a very scattered and uncoordinated way, often through individual initiatives from Earth Observation mission operators, scientific institutes dealing with ground measurements, service companies or data catalogues. In the discourse of Spatial Data Infrastructures, there are "catalogue services" - directories containing information on where spatial data and services can be found. For metadata "records" describing spatial data and services, there are "registries". The Geospatial industry coins specifications for search interfaces, where it might do better to reach out to other information retrieval and Internet communities. These considerations are the basis for the GENESI-DR scientific portal, which adopts a simple model allowing the geo-spatial classification and discovery of

  9. The role of petrology in defining volcanic hazards and designing monitoring systems

    NASA Astrophysics Data System (ADS)

    Smith, I. E.; Turner, M. B.; Price, R. C.; Cronin, S. J.

    2011-12-01

    Petrology is the study of magmatic systems; physical volcanology investigates processes of eruption. Physical volcanology provides the pre-eminent underpinning of the practical business of defining hazard scenarios, planning mitigation and designing monitoring strategies. Recent research in a variety of volcanic settings has demonstrated an important link between the petrologic processes that at a fundamental level drive the behavior of volcanoes and the processes that determine the eruptive style of a volcano. Together these define the hazards that arise from volcanic eruptions. Petrological studies of volcanoes are typically based on a study of lava because coherent rock is less vulnerable to weathering and alteration and is more durable in the geological record. Pyroclastic materials are commonly friable and glassy, are more easily eroded, and are more difficult to use in the analytical techniques that have become the staple basis of petrological studies. However, pyroclastic materials represent a complementary but different part of the magmatic story and it is only by integrating both effusive and explosive components of an eruption sequence that a complete picture of the behavior of the system feeding a volcano can be gained. Andesitic strato-cones are made up of a cone-building facies consisting mainly of primary magmatic products and usually dominated by lava flows because pyroclastic material is easily eroded from the slopes of a steep cone. The surrounding ring plain facies includes primary pyroclastic deposits but is typically dominated by redistributed material in the form of debris flow and lahar deposits together with reworked fluvial material. The deposits of each of these two facies are assembled on different time scales and they contain different aspects of the record of the evolution of the magmatic system that gave rise to them. An important practical consequence of this is that different parts of the geochemical record of the system can occur in

  10. Ore petrology of chromite-PGE mineralization in the Kempirsai ophiolite complex

    NASA Astrophysics Data System (ADS)

    Distler, V. V.; Kryachko, V. V.; Yudovskaya, M. A.

    2008-01-01

    The platinum group minerals (PGM) in chromite ores of the Kempirsai ophiolite massif, located south of the Ural Mountains, are extremely varied in composition and represented predominantly by alloys, sulfides, arsenides, and sulfosalts of the iridium-group PGE (IPGE). The earlier Ir-Os-Ru alloys prevail over the later Cu-Os-Ru, Cu-Ir, Ni-Ir, Ni-Os-Ir-Ru, and Ni-Ru-Os-Fe alloys rich in base metals (BM). The earlier Ru-Os disulfides crystallize coevally with Ir-Os-Ru alloys, whereas the later sulfides are represented by compounds with a variable stoichiometry and a wide miscibility of Ni, Cu, Ir, Rh, Os, and Fe. Phase relations of PGE alloys with PGE-BM alloys, sulfides and sulfoarsenides confirm that deposition of these minerals was defined by a general evolution of PGE fractionation in the mineral-forming system but not by a super-imposed process. The leading mechanism of PGM crystallization is thought to be their dendritic growth during gas-transport reactions from low-density gaseous fluid enriched in PGE. The representative technological sampling of 0.5 million tons of an ore showed that the average PGE content in chromite ore is 0.71 ppm which leads to an evaluation of the PGE resources to be no less than 250 tons. Hence, the Kempirsai deposit is not only a giant chromium deposit, but also a giant deposit of IPGE: Ir, Ru, and Os. The size parameters of PGM and their aggregates suggests that the PGE may be recoverable in separate concentrates.

  11. Chronology and Petrology of Silicates From IIE Iron Meteorites: Evidence of a Complex Parent Body Evolution

    NASA Technical Reports Server (NTRS)

    Bogard, Donald D.; Garrison, Daniel H.; McCoy, Timothy J.

    1999-01-01

    IIE iron meteorites contain silicate inclusions whose characteristics suggest a parent body similar to that of H-chondrites. However, these silicates show a wide range of alteration, ranging from Netschadvo and Techado, whose inclusions are little altered. to highly differentiated silicates like-those in Kodaikanal, Weekeroo Station and Colomera, which have lost metal and sulfur and are enriched in feldspar. We find these inclusions to show varying degrees of shock alteration. Because only a limited amount of data on - isotopic ages of HE silicates were available, we made Ar-39 - Ar-40 age determinations of Watson, Techado, miles Colomera, and Sombrerete. Watson has an Ar-Ar age of 3.653 +/- 0.012 Gyr, similar to previously reported ages for Kodaikanal and Netschadvo. We suggest that the various determined radiometric ages of these three meteorites were probably reset by a common impact event. The space exposure ages for these three meteorites are also similar to each other and are considerably younger than exposure ages of other IIEs. Ar-39 - Ar-40 ages inferred for the other four meteorites analyzed are considerably older than Watson and are: Techado =4.49 +/- 0.01 Gyr, Miles =4.412 +/- 0.016 Gyr, Colomera =4.469 +/- 0.012 Gyr, and Sombrerete =4.535 +/- 0.005 Gyr. These ages are in fair agreement with previously reported Rb-Sr isochron ages for Colomera and Weekeroo Station. Although several mechanisms to form HE meteorites previously were suggested, it is not obvious that a single mechanism could produce a suite of meteorites with very different degrees of silicate differentiation and with isotopic ages that differ by >0.8 Gyr. We suggest that those IIEs with older isotopic ages are a product of partial melting and differentiation within the parent body, followed by mixing of silicate and metal while both were relatively hot. Netschadvo and Watson may have formed by this same process or by impact mixing about 4.5 Gyr ago, but their isotopic ages were subsequently reset by shock heating. Kodaikanal apparently is required to have formed more recently, in which case impact melting and differentiation seems the only viable process. We see no compelling reasons to believe that IIE silicate and metal derived from different parent bodies or that the parent body of IIEs was the same as that of H-chondrites.

  12. 3D Integrated geophysical-petrological modelling of the Iranian lithosphere

    NASA Astrophysics Data System (ADS)

    Mousavi, Naeim; Ardestani, Vahid E.; Ebbing, Jörg; Fullea, Javier

    2016-04-01

    The present-day Iranian Plateau is the result of complex tectonic processes associated with the Arabia-Eurasia Plate convergence at a lithospheric scale. In spite of previous mostly 2D geophysical studies, fundamental questions regarding the deep lithospheric and sub-lithospheric structure beneath Iran remain open. A robust 3D model of the thermochemical lithospheric structure in Iran is an important step toward a better understanding of the geological history and tectonic events in the area. Here, we apply a combined geophysical-petrological methodology (LitMod3D) to investigate the present-day thermal and compositional structure in the crust and upper mantle beneath the Arabia-Eurasia collision zone using a comprehensive variety of constraining data: elevation, surface heat flow, gravity potential fields, satellite gravity gradients, xenoliths and seismic tomography. Different mantle compositions were tested in our model based on local xenolith samples and global data base averages for different tectonothermal ages. A uniform mantle composition fails to explain the observed gravity field, gravity gradients and surface topography. A tectonically regionalized lithospheric mantle compositional model is able to explain all data sets including seismic tomography models. Our preliminary thermochemical lithospheric study constrains the depth to Moho discontinuity and intra crustal geometries including depth to sediments. We also determine the depth to Curie isotherm which is known as the base of magnetized crustal/uppermost mantle bodies. Discrepancies with respect to previous studies include mantle composition and the geometry of Moho and Lithosphere-Asthenosphere Boundary (LAB). Synthetic seismic Vs and Vp velocities match existing seismic tomography models in the area. In this study, depleted mantle compositions are modelled beneath cold and thick lithosphere in Arabian and Turan platforms. A more fertile mantle composition is found in collision zones. Based on our 3

  13. Magma genesis, storage and eruption processes at Aluto volcano, Ethiopia: lessons from remote sensing, gas emissions and geochemistry

    NASA Astrophysics Data System (ADS)

    Hutchison, William; Biggs, Juliet; Mather, Tamsin; Pyle, David; Gleeson, Matthew; Lewi, Elias; Yirgu, Gezahgen; Caliro, Stefano; Chiodini, Giovanni; Fischer, Tobias

    2016-04-01

    One of the most intriguing aspects of magmatism during the transition from continental rifting to sea-floor spreading is that large silicic magmatic systems develop within the rift zone. In the Main Ethiopian Rift (MER) these silicic volcanoes not only pose a significant hazard to local populations but they also sustain major geothermal resources. Understanding the journey magma takes from source to surface beneath these volcanoes is vital for determining its eruption style and for better evaluating the geothermal resources that these complexes host. We investigate Aluto, a restless silicic volcano in the MER, and combine a wide range of geochemical and geophysical techniques to constrain magma genesis, storage and eruption processes and shed light on magmatic-hydrothermal-tectonic interactions. Magma genesis and storage processes at Aluto were evaluated using new whole-rock geochemical data from recent eruptive products. Geochemical modelling confirms that Aluto's peralkaline rhyolites, that constitute the bulk of recent erupted products, are generated from protracted fractionation (>80 %) of basalt that is compositionally similar to rift-related basalts found on the margins of the complex. Crustal melting did not play a significant role in rhyolite genesis and melt storage depths of ~5 km can reproduce almost all aspects of their geochemistry. InSAR methods were then used to investigate magma storage and fluid movement at Aluto during an episode of ground deformation that took place between 2008 and 2010. Combining new SAR imagery from different viewing geometries we identified an accelerating uplift pulse and found that source models support depths of magmatic and/or fluid intrusion at ~5 km for the uplift and shallower depths of ~4 km for the subsidence. Finally, gas samples collected on Aluto in 2014 were used to evaluate magma and fluid transport processes. Our results show that gases are predominantly emanating from major fault zones on Aluto and that they

  14. Maneuver Design and Calibration for the Genesis Spacecraft

    NASA Technical Reports Server (NTRS)

    Williams, Kenneth E.; Hong, Philip E.; Zietz, Richard P.; Han, Don

    2000-01-01

    Genesis is the fifth mission selected as part of NASA's Discovery Program. The objective of Genesis is to collect solar wind samples for a period of approximately two years while in a halo orbit about the Earth-Sun L I point. At the end of this period, the samples are to be returned to a specific recovery point on the Earth for subsequent analysis. This goal has never been attempted before and presents a formidable challenge in terms of mission design and operations, particularly planning and execution of propulsive maneuvers. To achieve a level of cost-effectiveness consistent with a Discovery-class mission, the Genesis spacecraft design was adapted to the maximum extent possible from designs used on earlier missions, such as Mars Global Surveyor (MGS) and Stardust, another sample collection mission. The spacecraft design for Genesis is shown. Spin stabilization was chosen for attitude control, in lieu of three-axis stabilization, with neither reaction wheels nor accelerometers included. This precludes closed-loop control of propulsive maneuvers and implies that any attitude changes, including spin changes and precessions, will behave like translational propulsive maneuvers and affect the spacecraft trajectory. Moreover, to minimize contamination risk to the samples collected, all thrusters were placed on the side opposite the sample collection canister. The orientation and characteristics of thrusters are indicated. For large maneuvers (>2.5 m/s), two 5 lbf thrusters will be used for delta v, with precession to the burn attitude, followed by spin-up from 1.6 to 10 rpm before the burn and spin down to 1.6 rpm afterwards, then precession back to the original spin attitude. For small maneuvers (<2.5 m/s), no spin change is needed and four 0.2 lbf thrusters are used for Av. Single or double 360 deg. precession changes are required whenever the desired delta v falls inside the two-way turn circle (about 0.4 m/s) based on the mass properties, spin rate and lever arm

  15. Petrological, Magnetic and Geochemical Characterization of Cretaceous-Paleogene Boundary El Mimbral and La Lajilla Sections, Northeastern Mexico

    NASA Astrophysics Data System (ADS)

    Ortega Nieto, A.; Fucugauchi, J. U.; Perez-Cruz, L. L.

    2009-12-01

    We present initial results of a petrological, magnetic and geochemical study of El Mimbral and La Lajilla sections that span the Cretaceous-Paleogene (K-Pg) boundary. K-Pg sections in northeastern Mexico have been intensively studied in past years, mainly because of their relationship to the Chicxulub crater in the Yucatan platform and for investigating the nature, origin, stratigraphic relations and age of the impact ejecta deposits. The K-Pg boundary is preserved in between hemipelagic marls and limestones of the Mendez (Maastrichtian) and Velasco (Paleocene) formations. The two sections are situated about 1000 km away from Chicxulub and K-Pg deposits are part of the proximal ejecta and the complex channelized siliciclastic units. We had separated the siliciclastic units into two parts, with a basal coarse poorly graded spherulitic bed some 0.2 to 1 m thick and a second part with several sandstone siltstone beds that have been grouped in various ways in previous studies. In the field, samples were collected across stratigraphic profiles for rock magnetic, petrological and geochemical analyses. Using field observations and analytical data, detailed columns for the two localities are prepared. Rock magnetic measurements include susceptibility, remanent and isothermal magnetization and remanent coercivity. Magnetic hysteresis loops and IRM and back-field demagnetization were measured for samples of spherulitic bed. X-ray fluorescence analyses on whole rock were complemented with previous data obtained for the Mimbral section by atomic absorption spectrometry and inductively coupled plasma mass spectrometry (including platinum group elements). Further detailed analysis concentrated in the ejecta material. The spherulitic bed is characterized by Fe-Mg rich chlorite and Si-Al-K rich glass spherules and carbonate accretionary lapilli spherules. The silicic component spherules are altered to calcite or chlorite-smectite, with some retaining glass cores. Spherules have

  16. Evolution of Pleistocene to Holocene eruptions in the Lesser Caucasus Mts:Insights from geology, petrology, geochemistry and geochronology

    NASA Astrophysics Data System (ADS)

    Savov, Ivan; Meliksetian, Khachatur; Connor, Charles; Karakhanian, Arkadi; Sugden, Patrick; Navasardyan, Gevorg; Halama, Ralf; Ishizuka, Osamu; Connor, Laura; Karapetian, Sergei

    2016-04-01

    Both effusive and highly explosive (VEI>5) and often voluminous caldera volcanism has developed atop the collision zone between the Arabian and the Eurasian plates. Currently what is exposed on the Anatolian-Armenian-Iranian active orogenic plateau is post-Mesozoic felsic to intermediate collision-related plutons, and mostly collision or post-collision related Quaternary volcanic structures. We have studied in detail the volcanism, tectonics and geophysics on the territory of E.Turkey and Armenia, where several large stratovolcanoes (Ararat, Lesser Ararat, Aragats, Tsghuk, Ishkhanasar) are surrounded by distinct monogenetic volcanic fields (distributed volcanism). These large in volume stratovolcanoes and the associated low volume monogenetic cones range from normal calk-alkaline to high-K shoshonitic in affinity, with their products ranging from basanites to high K trachytes and rhyolites. Several volcanic provinces, namely Kechut/Javakheti, Aragats, Gegham, Vardenis and Syunik are recognized in Armenia and each of them has > 100 mapped volcanoes. These have distinct geochemical (mineral chemistry, trace element and Sr-Nd-B isotope systematics) and petrological (melt eruption temperatures and volatile contents) fingerprints that may or may not vary over time. Age determinations and volcano-stratigraphy sections for each of the case studies we aim to present shows that the volcanism includes a continuous record from Pleistocene to Holocene, or even historical eruptions. The excellent volcano exposures and the now complete high resolution database (GIS), geological mapping, and new and improved K-Ar and Ar-Ar geochronology, uniquely allows us to evaluate the driving forces behind the volcanism in this continent-continent collision setting that is uniquely associated with long lasting eruption episodes. We shall compare the now well studied historical/Holocene eruptions with those pre-dating them, with the aim to identify possible geochemical or petrological

  17. A detailed petrological analysis of hydrated, low-nickel, nonchondritic stratospheric dust particles

    NASA Astrophysics Data System (ADS)

    Rietmeijer, Frans J. M.

    A detailed petrological analysis of three low-Ni, K-bearing, nonchondritic stratospheric dust particles is performed, and these particles are compared to products of high-energy, explosive (Plinian-type) volcanic events. The analytical electron microscope (AEM) analyses show pervasive layer silicates, carbonate and goethite, and chemical fractionation in the matrix of these particles similar to hydrothermal alteration in volcanic ejecta. Along with low Ni content and the presence of potassium, the texture and mineralogy of particles L2001-18, L2001-20, and L2002 C2 are similar to at least two nonchondritic stratospheric dust particles of the igneous subgroup for which an extraterrestrial origin has been suggested based on their minor- and trace-element abundances. The petrological characteristics of some low-Ni, K-bearing nonchondritic stratospheric dust particles supports a probable terrestrial volcanic origin, but the AEM data alone cannot exclude an extraterrestrial origin for these particles.

  18. PETRO.CALC.PLOT, Microsoft Excel macros to aid petrologic interpretation

    USGS Publications Warehouse

    Sidder, G.B.

    1994-01-01

    PETRO.CALC.PLOT is a package of macros which normalizes whole-rock oxide data to 100%, calculates the cation percentages and molecular proportions used for normative mineral calculations, computes the apices for ternary diagrams, determines sums and ratios of specific elements of petrologic interest, and plots 33 X-Y graphs and five ternary diagrams. PETRO.CALC.PLOT also may be used to create other diagrams as desired by the user. The macros run in Microsoft Excel 3.0 and 4.0 for Macintosh computers and in Microsoft Excel 3.0 and 4.0 for Windows. Macros provided in PETRO.CALC.PLOT minimize repetition and time required to recalculate and plot whole-rock oxide data for petrologic analysis. ?? 1994.

  19. MinChem: A Prototype Petrologic Database for Hanford Site Sediments

    SciTech Connect

    Mackley, Rob D.; Last, George V.; Serkowski, John A.; Middleton, Lisa A.; Cantrell, Kirk J.

    2010-09-01

    A prototype petrologic database (MinChem) has been under continual development for several years. MinChem contains petrologic, mineralogical, and bulk-rock geochemical data for Hanford Site sediments collected over multiple decades. The database is in relational form and consists of a series of related tables modeled after the Hanford Environmental Information System HEIS (BHI 2002) structures. The HEIS-compatible tables were created in anticipation of eventual migration into HEIS, or some future form of HEIS (e.g. HEIS-GEO). There are currently a total of 13,129 results in MinChem from 521 samples collected at 381 different sampling sites. These data come from 19 different original source documents published and unpublished (e.g. letter reports) between 1976 and 2009. The data in MinChem consist of results from analytical methods such as optical and electron microscopy, x-ray diffraction, x-ray fluorescence, and electron probe microanalysis.

  20. Petrological cannibalism: the chemical and textural consequences of incremental magma body growth

    NASA Astrophysics Data System (ADS)

    Cashman, Kathy; Blundy, Jon

    2013-09-01

    fluxing the reservoir with CO2-rich vapors that are either released from deeper in the system or transported with the recharge magma. Temperature fluctuations of 20-40 °C, on the other hand, are an inevitable consequence of incremental, or pulsed, assembly of crustal magma bodies wherein each pulse interacts with ancestral, stored magmas. We venture that this "petrological cannibalism" accounts for much of the plagioclase zoning and textural complexity seen not only at Mount St. Helens but also at arc magmas generally. More broadly we suggest that the magma reservoir below Mount St. Helens is dominated by crystal mush and fed by frequent inputs of hotter, but compositionally similar, magma, coupled with episodes of magma ascent from one storage region to another. This view both accords with other independent constraints on the subvolcanic system at Mount St. Helens and supports an emerging view of many active magmatic systems as dominantly super-solidus, rather than subliquidus, bodies.

  1. Geology, petrology and tectonic significance of the Mesozoic Paleoceanic terranes of the Vizcaino Peninsula, Baja California Sur, Mexico

    NASA Astrophysics Data System (ADS)

    Moore, T. E.

    The Viscaino Terrane, which is the most outboard terrane of mainland Baja California, can be divided into three principal terranes on the Vizcaino Peninsula. The structurally lowest is the disrupted composite Puerto Nuevo terrane which is represented by metamorphosed blocks in a serpentinite-matrix melange. The Viscaino Norte terrane structurally overlies the Puerto Nuevo terrane along a low-angle contact. To the south, the Vizcaino Sur terrane exposes a sequence consisting of ophiolite, tuffaceous chart and limestone of the San Hipolito Formation of Late Triassic age. Based on the petrologic, geochemical, and stratigraphic characteristics, the ophiolites of the Vizcaino Norte and Vizcaino Sur terranes are interpreted to have been formed in one or more marginal basin island arc systems during the Late Triassic whereas the ophiolitic rocks of the Puerto Nuevo terrane most likely formed at a midocean ridge. The subsequent pre-Upper Jurassic island arc deposits of the terranes are entirely volcanogenic and biogenic and contain no evidence of close proximity to a cratonal source. It is suggested that for as much as 80 my, the terranes were probably not associated with a continental margin as a fringing island arc, but instead represent allochthonous fragments of a paleogeographically complex paleo-Pacific Ocean.

  2. Sample Return Missions Where Contamination Issues are Critical: Genesis Mission Approach

    NASA Technical Reports Server (NTRS)

    Allton, Judith H.; Stansbery E. K.

    2011-01-01

    The Genesis Mission, sought the challenging analytical goals of accurately and precisely measuring the elemental and isotopic composition of the Sun to levels useful for planetary science, requiring sensitivities of ppm to ppt in the outer 100 nm of collector materials. Analytical capabilities were further challenged when the hard landing in 2004 broke open the canister containing the super-clean collectors. Genesis illustrates that returned samples allow flexibility and creativity to recover from setbacks.

  3. Mineralogy, Petrology, Chronology, and Exposure History of the Chelyabinsk Meteorite and Parent Body

    NASA Technical Reports Server (NTRS)

    Righter, K.; Abell, P.; Agresti, D.; Berger, E. L.; Burton, A. S.; Delaney, J. S.; Fries, M. D.; Gibson, E. K.; Harrington, R.; Herzog, G. F.; Keller, L. P.; Locke, D.; Lindsay, F.; McCoy, T. J.; Morris, R. V.; Nagao, K.; Nakamura-Messenger, K.; Niles, P. B.; Nyquist, L.; Park, J.; Peng, Z. X.; Shih, C. Y.; Simon, J. I.; Swisher, C. C., III; Tappa, M.

    2015-01-01

    The Chelyabinsk meteorite fall on February 15, 2013 attracted much more attention worldwide than do most falls. A consortium led by JSC received 3 masses of Chelyabinsk (Chel-101, -102, -103) that were collected shortly after the fall and handled with care to minimize contamination. Initial studies were reported in 2013; we have studied these samples with a wide range of analytical techniques to better understand the mineralogy, petrology, chronology and exposure history of the Chelyabinsk parent body.

  4. Apollo 17, Station 6 boulder sample 76255 - Absolute petrology of breccia matrix and igneous clasts

    NASA Technical Reports Server (NTRS)

    Warner, J. L.; Phinney, W. C.; Simonds, C. H.

    1976-01-01

    The matrix of 76255 is the finest-grained, most clast-laden, impact-melt polymict breccia sampled from the Station 6 boulder. The paper speculates on how the matrix of 76255 fits into and enhances existing thermal models of breccia lithification. Emphasis is on the detailed petrology of five lithic clasts, two of which display mineralogical and textural affinities to mare basalts, while three, a gabbro, a norite, and a troctolite are considered primitive plutonic rocks.

  5. Petrology and Geochemistry of New Paired Martian Meteorites Larkman Nunatak 12240 and Larkman Nunatak 12095

    NASA Technical Reports Server (NTRS)

    Funk, R. C.; Peslier, A. H.; Brandon, A. D.; Humayun, M.

    2016-01-01

    Two of the latest Martian meteorites found in Antarctica, paired olivine-phyric shergottites LAR 12240 and LAR 12095, are described in order to decipher their petrological context, and place constraints on the geological history of Mars. This project identifies all phases found in LAR 12240 and 12095 and analyzes them for major and trace elements. The textural relationships among these phases are examined in order to develop a crystallization history of the magma(s) that formed these basalts.

  6. Distribution of terrestrial age and petrologic type of meteorites from western Libya

    NASA Technical Reports Server (NTRS)

    Jull, A. J. T.; Donahue, D. J.; Wlotzka, F.; Palme, H.

    1990-01-01

    A group of 54 meteorites have been recovered from Daraj, Western Libya. After assessment of pairing of samples, using petrologic criteria, C-14 terrestrial ages were obtained on 13 samples selected from 9 different fall events. Eleven of the ages range from 3500 to 7600 years, with only two samples having ages in excess of 10,000 years. The cutoff in ages may be related to the timing of climatic changes in the Hammadah al Hamra.

  7. Research in volcanic geology, petrology and planetary science at MIT, 1969 to 1974

    NASA Technical Reports Server (NTRS)

    Mcgetchin, T. R.

    1974-01-01

    The behavior of volcanoes was studied by geologic mapping, petrologic investigations of lava and xenoliths, physical measurements, and theoretical modelling. Field observations were conducted in Alaska (Nunivak Island), Iceland, Hawaii (Mauna Kea), Italy (Etna, Stromboli), and Arizona. The results are discussed and compared with known data for lunar and planetary gelogy. Field methods used for the volcano research are cited and a list is given of all participating scientists and students. Publications and abstracts resulting from the research are also listed.

  8. Studies of Brazilian meteorites. XIV - Mineralogy, petrology, and chemistry of the Conquista, Minas Gerais, chondrite

    NASA Technical Reports Server (NTRS)

    Keil, K.; Kirchner, E.; Gomes, C. B.; Jarosewich, E.; Murta, R. L. L.

    1978-01-01

    The Conquista chondrite is described and classified as an H4. The mineral composition is reported. H-group classification is based on described microscopic, electron microprobe, and bulk chemical studies. The evidence for petrologic type 4 classification includes the pronounced well-developed chondritic texture; the slight compositional variations in constituent phases; the high Ca contents of pyroxene and the presence of pigeonite; glassy to microcrystalline interstitial material rich in alkalis and SiO2; and twinned low-Ca clinopyroxene.

  9. Report of the Workshop on Unmixing the SNCs: Chemical, Isotopic, and Petrologic Components of Martian Meteorites

    NASA Technical Reports Server (NTRS)

    Treiman, Allan H. (Editor); Herd, Christopher D. K. (Editor)

    2002-01-01

    Geochemical and petrologic studies of the Martian meteorites (nicknamed the SNCs) have proliferated in the past few years, from a wealth of new samples and the perfection of new analytical methods. An intriguing result from these studies is that the chemical and isotopic compositions of the Martian meteorites, all basalts or derived from basaltic magma, can be modeled as mixtures of a limited number of components. These mixing components were the focus of the workshop.

  10. GENESIS SciFlo: Enabling Multi-Instrument Atmospheric Science Using Grid Workflows

    NASA Astrophysics Data System (ADS)

    Wilson, B. D.; Tang, B.; Manipon, G.; Yunck, T.; Fetzer, E.; Braverman, A.; Dobinson, E.

    2004-12-01

    The General Earth Science Investigation Suite (GENESIS) project is a NASA-sponsored partnership between the Jet Propulsion Laboratory, academia, and NASA data centers to develop a new suite of web services tools to facilitate multi-sensor investigations in Earth System Science. The goal of GENESIS is to enable large-scale, multi-instrument atmospheric science using combined datasets from the AIRS, MODIS, MISR, and GPS sensors. Investigations will include cross-comparison of spaceborne climate sensors, cloud spectral analysis, study of upper troposphere-strato-sphere water transport, study of the aerosol indirect cloud effect, and global climate model validation. The challenges are to bring together very large datasets, reformat and understand the individual instrument retrievals, co-register or re-grid the retrieved physical parameters, perform computationally-intensive data fusion and data mining operations, and accumulate complex statistics over months to years of data. To meet these challenges, we are developing a Grid computing and dataflow framework, named SciFlo, in which we are deploying a set of versatile and reusable operators for data access, subsetting, registration, mining, fusion, compression, and advanced statistical analysis. SciFlo is a system for Scientific Knowledge Creation on the Grid using a Semantically-Enabled Dataflow Execution Environment. SciFlo leverages Simple Object Access Protocol (SOAP) Web Services and the Grid Computing standards (Globus Alliance toolkits), and enables scientists to do multi-instrument Earth Science by assembling reusable web services and executable operators into a distributed computing flow (operator tree). The SciFlo client & server engines optimize the execution of such distributed data flows and allow the user to transparently find and use datasets and operators without worrying about the actual location of the Grid resources. The scientist injects a distributed computation into the Grid by simply filling out

  11. Iron disulfide minerals and the genesis of roll-type uranium deposits.

    USGS Publications Warehouse

    Reynolds, R.L.; Goldhaber, M.B.

    1983-01-01

    Studies of the distribution of and textural relationships among pyrite and marcasite in host rocks for a number of roll-type sedimentary U deposits have enabled identification of several generations of FeS2 minerals. A critical factor influencing mineral formation is the complex relationship of pH and the S species that are precursors of FeS2 minerals. The presence or absence of intrinsic organic matter for bacterial sulphate reduction also plays a key role. In deposits lacking such organic matter, the pre-ore is often euhedral pyrite and the ore-stage is marcasite. In contrast, in deposits containing organic matter the pre-ore is pyrite occurring as framboids or as replacements of plant material, and the ore-stage is also pyrite. These contrasting FeS2 assemblages and their respective modes of origin are consistent with previously proposed biogenic and nonbiogenic theories of the genesis of roll-type U deposits. -J.E.S.

  12. GENSHELL: A genesis database 2D to 3D shell transformation program

    SciTech Connect

    Sjaardema, G.D.

    1993-07-01

    GENSHELL is a three-dimensional shell mesh generation program. The three-dimensional shell mesh is generated by mapping a two-dimensional quadrilateral mesh into three dimensions according to one of several types of transformations: translation, mapping onto a spherical, ellipsoidal, or cylindrical surface, and mapping onto a user-defined spline surface. The generated three-dimensional mesh can then be reoriented by offsetting, reflecting about an axis, revolving about an axis, and scaling the coordinates. GENSHELL can be used to mesh complex three-dimensional geometries composed of several sections when the sections can be defined in terms of transformations of two-dimensional geometries. The code GJOIN is then used to join the separate sections into a single body. GENSHELL updates the EXODUS quality assurance and information records to help track the codes and files used to generate the mesh. GENSHELL reads and writes two-dimensional and three-dimensional mesh databases in the GENESIS database format; therefore, it is compatible with the preprocessing, postprocessing, and analysis codes in the Sandia National Laboratories Engineering Analysis Code Access System (SEACAS).

  13. Genesis of self-identity as disother: life histories of people who stutter.

    PubMed

    Kathard, Harsha; Pillay, Mershen; Samuel, Michael; Reddy, Vijay

    2004-01-01

    This paper explores the processes shaping self-identity formation as DisOther and the actions of participants who stutter. It illuminates the experiences of adults who stutter using a biographical, narrative, life history methodology. The participants were seven South African adults of diverse racial, social and economic backgrounds from KwaZulu Natal, South Africa. Five males and two females were invited to participate via purposive and convenience sampling processes. Their stories of living with stuttering in their life worlds over time were constructed via biographical interviews using personal, social and temporal lenses typical of life history methodology. The interviews were audio-recorded and transcribed. The data were analysed at two levels using a combination of strategies. The first level entailed a narrative analysis that was represented as research stories for each participant. The cross-case and thematic analysis of research stories constituted the second level analysis of narratives. The findings explain the complex and interrelated personal and social processes over time which contribute to the genesis of self-identity formation as DisOther Social inscriptions of difference occurred in immediate home, school and work contexts over time via multiple processes such as labelling, norming, judging and teasing. Personal processes included discoveries of difference via critical events, repeated reinforcement of difference, self-judgement and temporal burdening. Furthermore, the actions participants took in negotiating stuttering were examined. The implications of the findings and limitations of the study are presented.

  14. Genesis of oil and hydrocarbon gases within Mars and carbonaceous chondrites from our solar system: organic origin (source rocks or direct biogenic sink?)

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, Prasanta K.

    2011-10-01

    The petroleum hydrocarbons (oil and gas) and kerogen macromolecules are abundant within the extraterrestrial atmospheric particles. These hydrocarbons occur as reservoir of lakes and oceans or in hydrate forms on various planets (Earth, Mars, moons of Saturn and Jupiter), asteroid belts, carbonaceous chondrites, and as solid residue within the planets or moons in the Solar System and beyond. The abundance of PAHs in the outer Solar System may indicate that the genesis of these primitive biomarker hydrocarbons may have formed abiogenically much earlier (> 5Ga) than the formation of our Solar System (~ 5 Ga). However, the origin of petroleum on Earth is overwhelmingly connected to the biogenic organic matter that is related to source rocks (thermal degradation of macromolecular kerogen). This may show a similar genesis of the kerogen macromolecules and petroleum hydrocarbons (oil and gas) within the carbonaceous chondrites (CCs), Mars, and selected moons from Saturn and Jupiter. They may be biologically and genetically related. Recent evidence of the possible presence of source rocks (organic rich black carbonaceous rocks) and associated petroleum system elements within Eberswalde and Holden areas of Mars may indicate similar terrestrial associations. Similarly, studies of Carbonaceous Chondrites using biological, petrological, SEM/EDS, and petroleum geochemical methods may also indicate the presence of source rock macromolecule within the CCs. These studies pointed out two new issues: (1) approximately, the major part of the CCs possibly originated from archaea, bacteria, and primitive algal remains; and (2) three types of temperature events affecting the petroleum generation within these carbonaceous chondrites: (i) lower temperature events (<200oC) in comets and cooler asteroids or planets (examples: Murchison, Tagish Lake, Orgueil); (ii) intermediate temperature events (200 - 300oC) as associated within the deeper section of the comets, asteroids or planets

  15. Re-Os, Sm-Nd, and Pb isotopic constraints on mantle and crustal contributions to magmatic sulfide mineralization in the Duluth Complex

    NASA Astrophysics Data System (ADS)

    Ripley, Edward M.; Lambert, David D.; Frick, Louise R.

    1998-10-01

    Previous petrologic and stable isotopic studies of sulfide mineralization in the Duluth Complex have led to the premise that sulfide genesis is strongly linked to the interaction between mantle-derived magmas and sedimentary country rocks in a rift zone environment. In order to more fully evaluate the nature of this interaction, and to gain an insight into the possible importance of externally derived metals in the ore-forming process, Pb, Sm-Nd, and Re-Os isotopic studies of the Babbitt Cu-Ni deposit were initiated. Rock-types examined include low-sulfide troctolite that show very little petrologic evidence for contamination, disseminated sulfide-bearing troctolitic to gabbroic rocks that occur close to the basal contact with country rocks and contain metasedimentary xenoliths, and massive sulfide. Lead isotopic values of whole rocks, plagioclase mineral separates, and massive sulfides show only subtle differences, and are compatible with 3 to 5% contamination of a mantle-derived melt with a Proterozoic crustal contaminant. ɛ Nd (1.1 Ga) values of the troctolite and gabbro samples are chondritic, and only the massive sulfides show strong evidence for contamination based on Sm-Nd isotopic values. Massive sulfides tend to be more sensitive indicators of contamination in the Sm-Nd system because of late-stage incorporation of a light rare earth element-rich fluid into a Ca-PO 4 (apatite) component of the immiscible sulfide liquid. γ Os (1.1 Ga) values are also strongly anomalous, and range from ˜500 to 1200 in disseminated sulfide-bearing troctolites and massive sulfides. These values are also consistent with from 1 to 3% contamination by C-rich and strongly radiogenic Proterozoic sedimentary rocks. Elemental and isotopic mass balance calculations suggest that up to 50% of the Pb and at least 35% of the Os in the sulfide mineralization have been derived from external sources. A corollary is that other metals may also be in part derived from external sources, which

  16. Genesis of avian influenza H9N2 in Bangladesh

    PubMed Central

    Shanmuganatham, Karthik; Feeroz, Mohammed M; Jones-Engel, Lisa; Walker, David; Alam, SMRabiul; Hasan, MKamrul; McKenzie, Pamela; Krauss, Scott; Webby, Richard J; Webster, Robert G

    2014-01-01

    Avian influenza subtype H9N2 is endemic in many bird species in Asia and the Middle East and has contributed to the genesis of H5N1, H7N9 and H10N8, which are potential pandemic threats. H9N2 viruses that have spread to Bangladesh have acquired multiple gene segments from highly pathogenic (HP) H7N3 viruses that are presumably in Pakistan and currently cocirculate with HP H5N1. However, the source and geographic origin of these H9N2 viruses are not clear. We characterized the complete genetic sequences of 37 Bangladeshi H9N2 viruses isolated in 2011–2013 and investigated their inter- and intrasubtypic genetic diversities by tracing their genesis in relationship to other H9N2 viruses isolated from neighboring countries. H9N2 viruses in Bangladesh are homogenous with several mammalian host-specific markers and are a new H9N2 sublineage wherein the hemagglutinin (HA) gene is derived from an Iranian H9N2 lineage (Mideast_B Iran), the neuraminidase (NA) and polymerase basic 2 (PB2) genes are from Dubai H9N2 (Mideast_C Dubai), and the non-structural protein (NS), nucleoprotein (NP), matrix protein (MP), polymerase acidic (PA) and polymerase basic 1 (PB1) genes are from HP H7N3 originating from Pakistan. Different H9N2 genotypes that were replaced in 2006 and 2009 by other reassortants have been detected in Bangladesh. Phylogenetic and molecular analyses suggest that the current genotype descended from the prototypical H9N2 lineage (G1), which circulated in poultry in China during the late 1990s and came to Bangladesh via the poultry trade within the Middle East, and that this genotype subsequently reassorted with H7N3 and H9N2 lineages from Pakistan and spread throughout India. Thus, continual surveillance of Bangladeshi HP H5N1, H7N3 and H9N2 is warranted to identify further evolution and adaptation to humans. PMID:26038507

  17. Genesis of avian influenza H9N2 in Bangladesh.

    PubMed

    Shanmuganatham, Karthik; Feeroz, Mohammed M; Jones-Engel, Lisa; Walker, David; Alam, SMRabiul; Hasan, MKamrul; McKenzie, Pamela; Krauss, Scott; Webby, Richard J; Webster, Robert G

    2014-12-01

    Avian influenza subtype H9N2 is endemic in many bird species in Asia and the Middle East and has contributed to the genesis of H5N1, H7N9 and H10N8, which are potential pandemic threats. H9N2 viruses that have spread to Bangladesh have acquired multiple gene segments from highly pathogenic (HP) H7N3 viruses that are presumably in Pakistan and currently cocirculate with HP H5N1. However, the source and geographic origin of these H9N2 viruses are not clear. We characterized the complete genetic sequences of 37 Bangladeshi H9N2 viruses isolated in 2011-2013 and investigated their inter- and intrasubtypic genetic diversities by tracing their genesis in relationship to other H9N2 viruses isolated from neighboring countries. H9N2 viruses in Bangladesh are homogenous with several mammalian host-specific markers and are a new H9N2 sublineage wherein the hemagglutinin (HA) gene is derived from an Iranian H9N2 lineage (Mideast_B Iran), the neuraminidase (NA) and polymerase basic 2 (PB2) genes are from Dubai H9N2 (Mideast_C Dubai), and the non-structural protein (NS), nucleoprotein (NP), matrix protein (MP), polymerase acidic (PA) and polymerase basic 1 (PB1) genes are from HP H7N3 originating from Pakistan. Different H9N2 genotypes that were replaced in 2006 and 2009 by other reassortants have been detected in Bangladesh. Phylogenetic and molecular analyses suggest that the current genotype descended from the prototypical H9N2 lineage (G1), which circulated in poultry in China during the late 1990s and came to Bangladesh via the poultry trade within the Middle East, and that this genotype subsequently reassorted with H7N3 and H9N2 lineages from Pakistan and spread throughout India. Thus, continual surveillance of Bangladeshi HP H5N1, H7N3 and H9N2 is warranted to identify further evolution and adaptation to humans.

  18. Cleaning at the Edge of Science: NASA's Genesis Mission

    NASA Technical Reports Server (NTRS)

    Stansbery, Eileen K.; Biesinger, Paul H.

    2000-01-01

    As part of NASA's continuing exploration of the origins of our solar system, the California Institute of Technology, Jet Propulsion Laboratory, Lockheed Martin Astronautics, Los Alamos National Laboratory, and the Johnson Space Center are working together to develop the Genesis mission to return solar matter for analysis in terrestrial laboratories. These samples will be used to define a baseline for the chemical and isotopic composition of the solar nebula. Deviations from the baseline resulted as the solar system evolved; thus, providing a tracer for materials incorporated into meteorites, comets and planetary bodies. These differences represent "fossil residues" that provide invaluable insight into how the solar nebula evolved to form the planets. We cannot collect a sample of the Sun as we would for a planet; fortunately, solar material comes to us in the form of the solar wind. Ultrapure materials will be exposed at the Earth-Sun L1, outside the Earth's magnetic influence, where solar wind nuclei will be captured for 2 years before returning to Earth in January 2001. The key challenge to obtaining a good sample of solar wind, uncontaminated by terrestrial atoms, is a clean collection surface in a clean sample canister and clean facilities with which to handle the samples for allocation and future reference. The Johnson Space Center QSQ is responsible for contamination control for the mission, for ensuring the cleanliness of collection surfaces and providing a clean environment for their subsequent handling. The level of cleanliness required is high; at the time of analysis (after sample return), the surface contamination by C, N, O must each be less than 10(exp 15) atoms per centimeter squared and for elements other than C, N, O, the number of atoms per centimeter squared of each surface contaminant shall not exceed the estimated solar wind fluence of the species (varies by element between U at approx. 10 (exp 4) atoms per centimeter squared to Fe, Si, Mg, and

  19. Fabric and petrological characteristics of serpentinized peridotites from the southern Mariana Trench

    NASA Astrophysics Data System (ADS)

    Michibayashi, K.; Uehara, S.; Ohara, Y.; Ishii, T.

    2011-12-01

    We analysed more than 100 peridotite samples from several sampling points in the southern Mariana Trench-the deepest oceanic trench in the world (10,924±10 m)-to better understand the development of the region. Petrological characteristics indicate the presence of two types of peridotites: those with a backarc origin (Site 1, ~144° E) and those from the forearc (Site 2, ~143.5E and Site 3, ~143E). The peridotites show petrological evidence for intense interaction with magma and/or fluid. This interaction has not influenced the fabric in the samples. On the basis of fabric intensity, the periodotites from Site 1 (backarc origin) and from the Mariana Trough record similar degrees of deformation, whereas the peridotites from Sites 2 and 3 (forearc origin) underwent lower-temperature deformation than did the serpentine seamounts. The spatial distribution of these petrological and fabric characteristics suggests that the mantle beneath the southern Mariana Trench is heterogeneous. Differences in secondary minerals such as serpentine minerals among the samples may reflect the ascent rate, indicating that the peridotites from Site 1 ascended at a higher rate and were serpentinized at a lower temperature (<250 degree C) compared with those from Sites 2 and 3 (>400 degree C).

  20. Petrology and thermal evolution of the Tinaquillo peridotite (Venezuela)

    NASA Astrophysics Data System (ADS)

    Seyler, Monique; Mattson, Peter H.

    1989-06-01

    The Tinaquillo peridotite complex is a layered and veined ultramafic-mafic body cropping out in the Cordillera de la Costa in northern Venezuela. Whole rock compositions, textures, and mineral chemistry of the peridotite and associated mafic rocks suggest that the complex underwent two major events before being emplaced into the Cordillera de la Costa. The peridotite first rose adiabatically within the upper mantle, at about 1350°C and 15-21 kbar pressure. This rise caused a small to medium degree of partial melting, resulting in the formation of a stratified complex of clinopyroxene-rich spinel lherzolites grading to harzburgites, interlayered with pyroxenite. The stratified complex then cooled and reequilibrated at about 800°-1000°C. A second upward movement of the peridotite brought it, still hot, from the upper mantle into lower crustal rocks (now called the Tinaco complex), at an estimated 7 kbar pressure, then cooling to 600°-700°C. The peridotite contains small amounts (2-5%) of homogeneously distributed pargasite. Locally, it is concentrated in amphibole veins grading into orthopyroxene- and spinel-hornblendite layers. Amphibolization was associated with metasomatism, and this metasomatic enrichment seems greater in the most depleted peridotite. The Tinaquillo peridotite shares many characteristics with Alpine spinel lherzolites that are believed to be derived from the subcontinental upper mantle and are emplaced within a continental rift, or at the margins of an oceanic rift. These characteristics are low degree of depletion, highly aluminous spinels, abundance of metasomatic facies, and early high-P equilibration followed by reequilibration with mafic-silicic continental type rocks within the intermediate-P granulite facies.

  1. Aerothermodynamic Environment Definition for the Genesis Sample Return Capsule

    NASA Technical Reports Server (NTRS)

    Cheatwood, F. McNeil; Merski, N. Ronald, Jr.; Riley, Christopher J.; Mitcheltree, Robert A.

    2001-01-01

    NASA's Genesis sample return mission will be the first to return material from beyond the Earth-Moon system. NASA Langley Research Center supported this mission with aerothermodynamic analyses of the sample return capsule. This paper provides an overview of that effort. The capsule is attached through its forebody to the spacecraft bus. When the attachment is severed prior to Earth entry, forebody cavities remain. The presence of these cavities could dramatically increase the heating environment in their vicinity and downstream. A combination of computational fluid dynamics calculations and wind tunnel phosphor thermography tests were employed to address this issue. These results quantify the heating environment in and around the cavities, and were a factor in the decision to switch forebody heat shield materials. A transition map is developed which predicts that the flow aft of the penetrations will still be laminar at the peak heating point of the trajectory. As the vehicle continues along the trajectory to the peak dynamic pressure point, fully turbulent flow aft of the penetrations could occur. The integrated heat load calculations show that a heat shield sized to the stagnation point levels will be adequate for the predicted environment aft of the penetrations.

  2. Climatology and Genesis Environment of North Atlantic Polar Lows

    NASA Astrophysics Data System (ADS)

    Michel, Clio; Spengler, Thomas

    2016-04-01

    Polar lows are intense maritime cyclones occurring during cold air outbreaks in high latitudes. We use the Melbourne University cyclone algorithm to detect and track polar lows. The algorithm employs the Laplacian of mean sea level pressure and is applied to the ERA-Interim reanalyses from 1979 to 2014. Track density maps indicate that polar lows mainly occur close to Svalbard, as well as in the northern Norwegian Sea and the Barents Sea. This is in accordance to previous studies about polar low tracks densities which are using less objective method and shorter time periods. Also the cyclogenesis density correlates well with the winter-time climatology of cold air outbreaks. Furthermore, we present inter- and intra-annual variability of polar lows and its relation to the NAO as well as sea ice extent. We also differentiated the polar low genesis environment into forward and reverse shear conditions, where forward shear implies that the thermal and mean wind are in the same direction, whereas they are opposite for reverse shear conditions. The forward and reverse shear results based on the objective tracking are similar to a previous study based on polar low tracks from the STARS data set provided by MET Norway.

  3. The Big Bang, Genesis, and Knocking on Heaven's Door

    NASA Astrophysics Data System (ADS)

    Gentry, Robert

    2012-03-01

    Michael Shermer recently upped the ante in the big bang-Genesis controversy by citing Lisa Randall's provocative claim (Science 334, 762 (2011)) that ``it is inconceivable that God could continue to intervene without introducing a material trace of his actions.'' So does Randall's and Shermer's agreement that no such evidence exists disprove God's existence? Not in my view because my 1970s Science, Nature and ARNS publications, and my article in the 1982 AAAS Western Division's Symposium Proceedings, Evolution Confronts Creation, all contain validation of God's existence via discovery of His Fingerprints of Creation and falsification of the big bang and geological evolution. These results came to wide public/scientific attention in my testimony at the 1981 Arkansas creation/evolution trial. There ACLU witness G Brent Dalrymple from the USGS -- and 2005 Medal of Science recipient from President Bush -- admitted I had discovered a tiny mystery (primordial polonium radiohalos) in granite rocks that indicated their almost instant creation. As a follow-up in 1992 and 1995 he sent out SOS letters to the entire AGU membership that the polonium halo evidence for fiat creation still existed and that someone needed to urgently find a naturalistic explanation for them. Is the physics community guilty of a Watergate-type cover-up of this discovery of God's existence and falsification of the big bang? For the answer see www.halos.tv.

  4. Pain perception and its genesis in the human brain.

    PubMed

    C N Chen, Andrew

    2008-10-25

    In the past two decades, pain perception in the human brain has been studied with EEG/MEG brain topography and PET/fMRI neuroimaging techniques. A host of cortical and subcortical loci can be activated by various nociceptive conditions. The activation in pain perception can be induced by physical (electrical, thermal, mechanical), chemical (capsacin, ascoric acid), psychological (anxiety, stress, nocebo) means, and pathological (e.g. migraine, neuropathic) diseases. This article deals mainly on the activation, but not modulation, of human pain in the brain. The brain areas identified are named pain representation, matrix, neuraxis, or signature. The sites are not uniformly isolated across various studies, but largely include a set of cores sites: thalamus and primary somatic area (SI), second somatic area (SII), insular cortex (IC), prefrontal cortex (PFC), cingulate, and parietal cortices. Other areas less reported and considered important in pain perception include brainstem, hippocampus, amygdala and supplementary motor area (SMA). The issues of pain perception basically encompass both the site and the mode of brain function. Although the site issue is delineared to a large degree, the mode issue has been much less explored. From the temporal dynamics, IC can be considered as the initial stage in genesis of pain perception as conscious suffering, the unique aversion in the human brain.

  5. Genesis of elevated aerosol loading over the Indian region

    NASA Astrophysics Data System (ADS)

    Prijith, S. S.; Rao, P. V. N.; Mohan, Mannil

    2016-05-01

    Elevated aerosols assume importance as the diabatic heating due to aerosol absorption is more intense at higher altitudes where the atmosphere becomes thinner. Indian region, especially its central and northern latitudes, experiences significant loading of elevated aerosols during pre-monsoon and summer months. Genesis of elevated aerosol loading over Indian region is investigated in the present study, using multi-year satellite observations from Cloud Aerosol Lidar with Orthogonal Polarization (CALIOP) and Moderate Resolution Imaging Spectroradiometer (MODIS) along with reanalysis winds from MERRA. Central India is observed to have prominent aerosols loading at higher altitudes during pre-monsoon season, whereas it is during summer months over north-west India. Further analysis reveals that the elevated aerosols over Indian region in pre-monsoon and summer months are significantly contributed by transported mineral dust from the arid continental regions at west. In addition to the mineral dust advection, aerosols at higher altitudes over Indian region are enriched by strong convection and associated vertical transport of surface level aerosols. Vertical transport of aerosols observed over Indian region during pre-monsoon and summer months is aided by intense convergence at the surface level and divergence at the upper level. Moreover, aerosol source/sink strength estimated using aerosol flux continuity equation show significant aerosol production over central India during pre-monsoon. Strong vertical transport prevails during pre-monsoon uplifts the locally produced aerosols, with considerable anthropogenic fraction, to higher altitudes where their impacts would be more intense.

  6. Deciphering the Minimal Algorithm for Development and Information-genesis

    NASA Astrophysics Data System (ADS)

    Li, Zhiyuan; Tang, Chao; Li, Hao

    During development, cells with identical genomes acquires different fates in a highly organized manner. In order to decipher the principles underlining development, we used C.elegans as the model organism. Based on a large set of microscopy imaging, we first constructed a ``standard worm'' in silico: from the single zygotic cell to about 500 cell stage, the lineage, position, cell-cell contact and gene expression dynamics are quantified for each cell in order to investigate principles underlining these intensive data. Next, we reverse-engineered the possible gene-gene/cell-cell interaction rules that are capable of running a dynamic model recapitulating the early fate decisions during C.elegans development. we further formulized the C.elegans embryogenesis in the language of information genesis. Analysis towards data and model uncovered the global landscape of development in the cell fate space, suggested possible gene regulatory architectures and cell signaling processes, revealed diversity and robustness as the essential trade-offs in development, and demonstrated general strategies in building multicellular organisms.

  7. Genesis Spacecraft Science Canister Preliminary Inspection and Cleaning

    NASA Technical Reports Server (NTRS)

    Hittle, J. D.; Calaway, M. J.; Allton, J. H.; Warren, J. L.; Schwartz, C. M.; Stansbery, E. K.

    2006-01-01

    The Genesis science canister is an aluminum cylinder (75 cm diameter and 35 cm tall) hinged at the mid-line for opening. This canister was cleaned and assembled in an ISO level 4 (Class 10) clean room at Johnson Space Center (JSC) prior to launch. The clean solar collectors were installed and the canister closed in the cleanroom to preserve collector cleanliness. The canister remained closed until opened on station at Earth-Sun L1 for solar wind collection. At the conclusion of collection, the canister was again closed to preserve collector cleanliness during Earth return and re-entry. Upon impacting the dry Utah lakebed at 300 kph the science canister integrity was breached. The canister was returned to JSC. The canister shell was briefly examined, imaged, gently cleaned of dust and packaged for storage in anticipation of future detailed examination. The condition of the science canister shell noted during this brief examination is presented here. The canister interior components were packaged and stored without imaging due to time constraints.

  8. XANES spectroscopy as a tool to trace phosphorus transformation during soil genesis and mountain ecosystem development from lake sediments

    NASA Astrophysics Data System (ADS)

    Giguet-Covex, C.; Poulenard, J.; Chalmin, E.; Arnaud, F.; Rivard, C.; Jenny, J.-P.; Dorioz, J.-M.

    2013-10-01

    The aim of this study is to investigate phosphorus (P) species modifications triggered by soil genesis and mountain ecosystem development after glacial retreat using a lake sediment archive (Lake Anterne, North French Alps). Five lake sediment samples, representative of different stages of soil and ecosystem development, were selected for P speciation analyses. Furthermore, a sequence of current soils from the catchment was analyzed to better constrain our interpretations of the lacustrine archive. Synchrotron techniques (X-ray Fluorescence (XRF) mapping and P K-edge X-ray absorption near edge structure (XANES) spectroscopy) were applied to lake sediments, soils, and standards (mineral and organic) to distinguish between different P species. The results show that soil development during the first millennia of the Holocene triggered increased P species diversity. At the onset of the Holocene, P was present as apatite when rocks and leptosols dominated the catchment. Pedogenic processes then led to apatite dissolution and the formation of large amounts of P on metal/clay-organic complexes. P geochemistry during the main step of soil genesis (early leptosols dominated by apatite, low weathered cambisols with P mainly adsorbed on iron oxides, highly weathered podzols with large amounts of P on Al/Fe/clay organic complexes) is thus clearly recorded in lake sediments. P K-edge XANES spectroscopy is particularly relevant as qualitative method to study P species in soils and lake sediments at high spatial resolution. Such resolution is needed to reveal the diversity of small P particles and like this better characterize the P cycle and improve our understanding of ecosystem evolution.

  9. Project Genesis: Mars in situ propellant technology demonstrator mission

    NASA Technical Reports Server (NTRS)

    Acosta, Francisco Garcia; Anderson, Scott; Andrews, Jason; Deger, Matt; Hedman, Matt; Kipp, Jared; Kobayashi, Takahisa; Marcelo, Mohrli; Mark, Karen; Matheson, Mark

    1994-01-01

    Project Genesis is a low cost, near-term, unmanned Mars mission, whose primary purpose is to demonstrate in situ resource utilization (ISRU) technology. The essence of the mission is to use indigenously produced fuel and oxidizer to propel a ballistic hopper. The Mars Landing Vehicle/Hopper (MLVH) has an Earth launch mass of 625 kg and is launched aboard a Delta 117925 launch vehicle into a conjunction class transfer orbit to Mars. Upon reaching its target, the vehicle performs an aerocapture maneuver and enters an elliptical orbit about Mars. Equipped with a ground penetrating radar, the MLVH searches for subsurface water ice deposits while in orbit for several weeks. A deorbit burn is then performed to bring the MLVH into the Martian atmosphere for landing. Following aerobraking and parachute deployment, the vehicle retrofires to a soft landing on Mars. Once on the surface, the MLVH begins to acquire scientific data and to manufacture methane and oxygen via the Sabatier process. This results in a fuel-rich O2/CH4 mass ratio of 2, which yields a sufficiently high specific impulse (335 sec) that no additional oxygen need be manufactured, thus greatly simplifying the design of the propellant production plant. During a period of 153 days the MLVH produces and stores enough fuel and oxidizer to make a 30 km ballistic hop to a different site of scientific interest. At this new location the MLVH resumes collecting surface and atmospheric data with the onboard instrumentation. Thus, the MLVH is able to provide a wealth of scientific data which would otherwise require two separate missions or separate vehicles, while proving a new and valuable technology that will facilitate future unmanned and manned exploration of Mars. Total mission cost, including the Delta launch vehicle, is estimated to be $200 million.

  10. The genesis of the northern Kettle Moraine, Wisconsin

    NASA Astrophysics Data System (ADS)

    Carlson, A. E.; Mickelson, D. M.; Principato, S. M.; Chapel, D. M.

    2005-04-01

    Interpreting past glacial dynamics from the glacial record requires that the depositional environments of glacial sediments and landforms be understood. In the case of interlobate deposits, models that incorporate various components of pro, supra and subglacial deposition have been developed and tested in the northern Kettle Moraine (nKM), Wisconsin; a large interlobate deposit that formed between the Green Bay and Lake Michigan lobes of the Laurentide Ice Sheet during the last deglaciation. In this paper, we interpret a new genesis for the nKM using sediment analysis and distribution along with landform distribution. In Sheboygan County, the nKM consists of two steep-sided, high-relief, hummocky ridges separated by a low elevation and low-relief central axis. Gravel in the bounding hummocky ridges is well-sorted and well-rounded. Some bedding is collapsed. Large, isolated moulin kames are restricted to the axis area and composed of relatively poorly sorted, more angular gravel and diamicton. The distribution of these different sediments and landforms are explained by the accumulation of supraglacial debris that insulated the ice below the axis of the nKM, while the melting of cleaner ice on either side formed channels on the ice surface. As deglaciation proceeded, a substantial thickness of well-rounded, stream-deposited sand and gravel accumulated on ice in the bounding channels. Eventual collapse of this sediment formed the two hummocky ridges. Poorly sorted debris along the axis fell and slid into moulins and larger collapse areas in the ice. Thus, differential debris insulation and ice ablation controlled the mainly supraglacial deposition of this part of the nKM.

  11. Genesis of the Costilla Reservoir sill, New Mexico

    SciTech Connect

    McDuffie, S.; Marsh, B.D. . Dept. of Earth and Planetary Sciences)

    1992-01-01

    The Costilla Reservoir sill is a 220 m-thick, tabular hypabyssal intrusion in the Latir volcanic field of north central New Mexico. This late Oligocene body consists of olivine-bearing basaltic andesite ranging from 53 to 57% SiO[sub 2]. The chemical variations are not due to in-situ crystal settling, for modal and whole rock chemical profiles reveal no such redistribution. Settling calculations predict a cumulate pile in such a large igneous body, so the absence of settling suggests that a single, thick molten sheet never existed. Hence the authors conclude emplacement was episodic, extending over a period commensurate with solidification time (100+ years). The lack of internal chill zones precludes injection over a significantly longer period. Since no crystals were redistributed post-emplacement, the chemical differences within the body result from the injection of initially heterogeneous magma. The first pulse of magma, which is represented by the 10--20 m nearest each contact, differs from the bulk of the sill in FeO[sub total], Sc, and average An content of plagioclase. The subsequent injections are not chemically uniform, but their variations are gradational. The chemical disparities within the Costilla magma cannot be fully explained by preplacement fractionation of the major phases (plag, olivine, cpx, opx). The heterogeneity may have existed from the time and place of magma genesis, which appears to be in the lower crust. The majority of pyroxene and feldspar phenocrysts exhibit features (extensive fracturing, disequilibrium textures) suggesting they did not crystallize directly from this magma. Rather, they may be restitic grains inherited from a partially melted source area. Additionally, some of these crystals have been spawned by the abundant supply of xenoliths, some of which were disaggregating in the magma.

  12. Age and genesis of Mansurovo suite, Southern Urals

    NASA Astrophysics Data System (ADS)

    Kouznetsov, N. B.; Stepanova, M. M.; Slavikova, N. V.; Kouznetsova, T. N.

    2003-04-01

    A summer 2002 student field camp was placed in the Southern Urals, Uchaly region, Mansurovo village, (54deg29`33``N, 59deg30`30``E). It is common adopted to consider that a typical Early Devonian sequence of south part of the Eastern Uralides (eastward of the Main Uralian Fault) is outcropped here. This sequence is named here Mansurovo suite. A large scale detailed geological map of area 2kmx2km and stratigraphic sequences were done. The Mansurovo sequence (1750m) was subdivided into 5 units: 1) large-scale olistoplaks of pillow-basalt, 2) olistolits and olistoplaks of black aleurolites with llandovery graptolites, 3) olistolits and olistoplaks of gray silicites, 4) sandstone, 5) mixture of silicites, limestone, tuffs, lava, etc. The rock bodies of 1, 2, 3, 5 units are buried into unsorted sand-gravel matrix. Late Ordovician Conodonts [Hamarodus brevirameus (Walliser), Periodon grandis Ethington, Scabbardella altipes (Henningsmoen), Periodon cf. grandis (Ethington), Belodina cf. confluence Sweet identification by S.Dubinina, GIN RAS] were firstly found into the olistolits of gray silicites, unit 3. The Mansurovo suit is covered by the Late Emsian Early Eifelian Irendik suit consisting of andesit-basaltic lava and tuffs. The next considerations allow us to reconsider the age and genesis of Mansurovo suite. (1) Fauna inversion: Ordovician silicites, unit 3 lay above Silurian aleurolites, unit 2. (2) Mansurovo suite is characterized by olistostrom structure. (3) Volcano-sedimentary rocks of Irendik suite are found into unit 5. All these imply that the age of Mansurovo olistostrom suit is not Early Devonian age, but is younger straton. The investigations are supported by RFBI (grant N 02-05-64283) and Federal Program “INTEGRATION”.

  13. The genesis solar-wind sample return mission

    SciTech Connect

    Wiens, Roger C

    2009-01-01

    , each theory predicting a different solar isotopic composition and each invoking a different early solar-system process to produce the heterogeneity. Other volatiles such as C, N, and H may also have experienced similar effects, but with only two isotopes it is often impossible to distinguish with these elements between mass-dependent fractionation and other effects such as mixing or mass-independent fractionation. Table 1 provides a summary of the major measurement objectives of the Genesis mission. Determining the solar oxygen isotopic composition is at the top of the list. Volatile element and isotope ratios constitute six of the top seven priorities. A number of disciplines stand to gain from information from the Genesis mission, as will be discussed later. Based on the Apollo solar-wind foil experiment, the Genesis mission was designed to capture solar wind over orders of magnitude longer duration and in a potentially much cleaner environment than the lunar surface.

  14. Time and metamorphic petrology: Calcite to aragonite experiments

    USGS Publications Warehouse

    Hacker, B.R.; Kirby, S.H.; Bohlen, S.R.

    1992-01-01

    Although the equilibrium phase relations of many mineral systems are generally well established, the rates of transformations, particularly in polycrystalline rocks, are not. The results of experiments on the calcite to aragonite transformation in polycrystalline marble are different from those for earlier experiments on powdered and single-crystal calcite. The transformation in the polycrystalline samples occurs by different mechanisms, with a different temperature dependence, and at a markedly slower rate. This work demonstrates the importance of kinetic studies on fully dense polycrystalline aggregates for understanding mineralogic phase changes in nature. Extrapolation of these results to geological time scales suggests that transformation of calcite to aragonite does not occur in the absence of volatiles at temperatures below 200??C. Kinetic hindrance is likely to extend to higher temperatures in more complex transformations.

  15. Minerologic and Petrologic Studies of Meteorites and Lunar Samples

    NASA Technical Reports Server (NTRS)

    Wood, John

    2000-01-01

    In the past year this group continued essentially full time research on extraterrestrial materials, and the question of the origin of the solar system. The continuing scientific staff consists of the P.I. and Visiting Scientist Michael Petaev. Vitae for Wood and Petaev appear in Sec. 6. We benefit from the part time services of a Project Administrator (Judith Terry) and a Secretary (Muazzez Lohmiller). In January 1999 the P.I. assumed the Chairmanship of COMPLEX, the Committee on Planetary and Lunar Exploration of the Space Studies Board, National Research Council. Wood and Petaev were authors or coauthors of 21 publications, new manuscripts, and abstracts in the last year. These are listed above, and referenced by number [n] in the discussion below. Other references to the literature made in this Section are listed in Sec. 3.

  16. Petrology of Aztec Wash pluton, Eldorado Mountains, southern Nevada

    SciTech Connect

    Falkner, C.M.; Miller, C.F. ); Wooden, J.L. )

    1993-04-01

    Aztec Wash pluton, a 50 km[sup 2] intrusive complex in the northern Eldorado Mountains, was emplaced ca. 16 Ma (Faulds et al., 1990) during extension within the Colorado River Corridor. The pluton displays extreme compositional variability, ranging from olivine gabbro (ca. 50 wt% SiO[sub 2]) to highly evolved aplite (76% SiO[sub 2]). Most of the intrusion is medium grained, homogeneous granite (ca. 72% SiO[sub 2]), but 1/3 is highly heterogeneous and dominated by mafic to intermediate rocks; a 6 [times] 3km, N-S mafic zone almost bisects the pluton. Well-displayed magma mingling and late mafic and felsic dikes verify the coexistence of mafic and felsic melts. Hornblende barometry indicates that the entire exposed portion of Aztec Wash pluton was emplaced at very shallow depth (complex pre-pluton deformational history. The authors propose the following emplacement history for Aztec Wash pluton: felsic magma intruded shallow levels of crust; the base of the magma chamber was intruded by basalt; after the upper portion of the initial magma was largely crystallized, basalt ascended into, perhaps remobilized, and mingled with felsic magma; this ascent may have been facilitated by E-W extension of the crystallizing pluton; more discrete syn- to post-pluton, mafic to felsic dikes mark additional intrusive pulses triggered by basalt intrusion and extensional fracturing. Field relations suggest that the mingling led to mixing in both the main units and the late dikes, but geochemical data indicate that mixing, if it occurred, was not a simple 2-end member process.

  17. Polytopic vector analysis in igneous petrology: Application to lunar petrogenesis

    NASA Technical Reports Server (NTRS)

    Shervais, John W.; Ehrlich, R.

    1993-01-01

    Lunar samples represent a heterogeneous assemblage of rocks with complex inter-relationships that are difficult to decipher using standard petrogenetic approaches. These inter-relationships reflect several distinct petrogenetic trends as well as thermomechanical mixing of distinct components. Additional complications arise from the unequal quality of chemical analyses and from the fact that many samples (e.g., breccia clasts) are too small to be representative of the system from which they derived. Polytopic vector analysis (PVA) is a multi-variate procedure used as a tool for exploratory data analysis. PVA allows the analyst to classify samples and clarifies relationships among heterogenous samples with complex petrogenetic histories. It differs from orthogonal factor analysis in that it uses non-orthogonal multivariate sample vectors to extract sample endmember compositions. The output from a Q-mode (sample based) factor analysis is the initial step in PVA. The Q-mode analysis, using criteria established by Miesch and Klovan and Miesch, is used to determine the number of endmembers in the data system. The second step involves determination of endmembers and mixing proportions with all output expressed in the same geochemical variable as the input. The composition of endmembers is derived by analysis of the variability of the data set. Endmembers need not be present in the data set, nor is it necessary for their composition to be known a priori. A set of any endmembers defines a 'polytope' or classification figure (triangle for a three component system, tetrahedron for a four component system, a 'five-tope' in four dimensions for five component system, et cetera).

  18. Petrology of the Plutonic Rocks of west-central Alaska

    USGS Publications Warehouse

    Miller, Thomas P.

    1970-01-01

    A series of plutons in west-central Alaska defines the Hogatza plutonic belt which extends for about 200 miles in an east-west direction from the northeastern Seward Peninsula to the Koyukuk River. The plutonic rocks have an aggregate area of about 1,200 square miles and their composition, distribution, and possible petrogenesis are discussed for the first time in this report. Field, petrographic and chemical data supported by K/Ar age dating indicate the plutonic rocks are divisible into two suites differing in age, location, and composition. The western plutons are mid-Cretaceous (~100 m.y.) in age and consist of a heterogeneous assemblage of monzonite, syenite, quartz monzonite. Associated with these granitic rocks is a group of alkaline sub-silicic rocks that forma belt of intrusive complexes extending for a distance of at least 180 miles from west-central Alaska to the Bering Sea. The complex at Granite Mountain shows a rare example of zoning from an alkaline rim to a quartz-bearing core. The occurrence of a similar complex at Cape Dezhnev on the easternmost tip of Siberia suggests the alkaline province may extend into Siberia. The easternmost plutons are Late Cretaceous (180 m.y.) in age and composed primarily of granodiorite and quartz monzonite similar to calc-alkaline plutons found throughout the North America Cordillera. The plutons are epizonal and intrude deformed but unmetamorphosed Lower Cretaceous andesitic volcanics and volcanic graywacke which constitute the highly mobile Yukon-Koyukuk volcanogenic province of west-central Alaska. No older rocks have been found within the confines of this vast tract; the occurrence of a bounding ophiolite sequence has lead to the suggestion that the province was formed by large-scale rifting and is underlain by oceanic crust. The possibility of no juvenile sialic crust over much of the area suggests that the potassium-rich magma now represented by the alkaline rocks originated in the mantle. The distribution of the

  19. Diffusion Modelling as a Useful Petrological Tool for Near-Real-Time Volcanic Eruption Monitoring

    NASA Astrophysics Data System (ADS)

    Couperthwaite, F.; Morgan, D. J.; Thordarson, T.; Shea, T.; Harvey, J.; Trusdell, F.; Pankhurst, M. J.

    2015-12-01

    Diffusion modelling is a well-established petrological technique for investigating the timescales of sub-surface processes occurring within magma storage bodies and transport systems prior to eruption. The technique typically produces - at best - results some weeks after a volcanic eruption has commenced. This contribution describes progress made on a user-friendly, easy-to-use petrological 'tool' that can be deployed in near-real time at the onset of and during an eruption. This is important for fast timescale retrieval (within days rather than weeks) without compromising the reliability of the timescale retrieved. This has implications for eruption monitoring and hazard mitigation, providing a petrological time-series complementing existing geophysical monitoring techniques. Current methods are constrained by data processing rates and the geometrical corrections required to control for random sectioning, crystal shape uncertainties and mineral anisotropy. Using a set of Piton de la Fournaise (Réunion Island) lava flow samples and a suite of Mauna Loa (HI, US) air fall and lava flow samples, magmatic timescales for Mg-Fe diffusion in olivine have been retrieved. Piton has a monodisperse crystal population, making a near-perfect baseline from which to pick apart the current diffusion modelling method. In so doing, a greater understanding of the sources of scatter and uncertainty in the process of timescale retrieval was obtained. The variety of potential sectioning orientations and their interaction with diffusion processes led to the proposal by Shea et al, 2015, in press, of selection rules to select boundaries, based on numerical models. Combined with evaluations of crystal shape, crystal axial ratios, interfacial angles, U-stage measurements and a statistical approach, such selection rules should allow the orientation of the grain within a sample to be inferred, negating the need for independent EBSD measurements and enabling a faster processing technique.

  20. Effect of pressure on closure temperature of a trace element in cooling petrological systems

    NASA Astrophysics Data System (ADS)

    Liang, Yan

    2017-03-01

    Closure temperature is important to many diffusion-related problems involving cooling. The classic model of Dodson and its modifications for cooling petrological systems are formulated at constant pressure. Many petrologic processes involve changes in both temperature and pressure. The effect of changing pressure on diffusional loss in cooling petrological systems has not been considered in Dodson's model. During upwelling, the decompression rate is related to the cooling rate through the slope of the upwelling path. Simple analytical expressions for the average or mean closure temperature and closure pressure in cooling-upwelling mono-mineralic and bi-mineralic systems are obtained by noting that both temperature and pressure decrease as a function of time along the upwelling path. These pressure-adjusted equations are nearly identical to closure temperature equations for isobaric cases if one replaces the activation energy and pre-exponential factor for diffusion in the isobaric formulations by the path-dependent activation energy and pre-exponential factor. The latter also depend on the slope of the upwelling path. The competing effects between pressure and temperature on diffusion during upwelling result in reductions in the effective activation enthalpy for diffusion and exchange enthalpy for partitioning, which in turn leads to systematic deviations in closure temperatures from cases of constant pressure. For systems with large activation volume for diffusion, it may be possible to deduce upwelling path and upwelling rate from closure temperatures and closure pressures of selected elements. Examples of closure temperature and closure pressure for REE diffusion in garnet and clinopyroxene and in garnet-clinopyroxene aggregates are presented and discussed in the context of the minor's rule and the REE-in-garnet-clinopyroxene thermobarometer. Closure temperatures for middle-to-heavy REE in garnet-clinopyroxene aggregates are controlled primarily by diffusion in

  1. Reconciling mantle attenuation-temperature relationships from seismology, petrology, and laboratory measurements

    NASA Astrophysics Data System (ADS)

    Abers, G. A.; Fischer, K. M.; Hirth, G.; Wiens, D. A.; Plank, T.; Holtzman, B. K.; McCarthy, C.; Gazel, E.

    2014-09-01

    attenuation measurements provide a powerful tool for sampling mantle properties. Laboratory experiments provide calibrations at seismic frequencies and mantle temperatures for dry melt-free rocks, but require ˜102-103 extrapolations in grain size to mantle conditions; also, the effects of water and melt are not well understood. At the same time, body wave attenuation measured from dense broadband arrays provides reliable estimates of shear wave attenuation (QS-1), affording an opportunity for calibration. We reanalyze seismic data sets that sample arc and back-arc mantle in Central America, the Marianas, and the Lau Basin, confirming very high attenuation (QS ˜ 25-80) at 1 Hz and depths of 50-100 km. At each of these sites, independent petrological studies constrain the temperature and water content where basaltic magmas last equilibrated with the mantle, 1300-1450°C. The QS measurements correlate inversely with the petrologically inferred temperatures, as expected. However, dry attenuation models predict QS too high by a factor of 1.5-5. Modifying models to include effects of H2O and rheology-dependent grain size shows that the effects of water-enhanced dissipation and water-enhanced grain growth nearly cancel, so H2O effects are modest. Therefore, high H2O in the arc source region cannot explain the low QS, nor in the back arc where lavas show modest water content. Most likely, the high attenuation reflects the presence of melt, and some models of melt effects come close to reproducing observations. Overall, body wave QS can be reconciled with petrologic and laboratory inferences of mantle conditions if melt has a strong influence beneath arcs and back arcs.

  2. Accretion, metamorphism, and brecciation of ordinary chondrites - Evidence from petrologic studies of meteorites from Roosevelt County, New Mexico

    NASA Technical Reports Server (NTRS)

    Scott, Edward R. D.; Taylor, G. Jeffrey; Keil, Klaus

    1986-01-01

    The olivines and pyroxenes from twenty-nine ordinary chondrites from Roosevelt County, New Mexico are examined. The mineralogical properties of the chondrites studied are described. Correlations between mineral compositions and petrologic type and between petrologic type and bulk chemistry are analyzed. It is observed that mean CaO concentrations in olivine show significant variations among equilibrated chondrites, but these are not correlated with petrologic type; the degree of heterogeneity of FeO concentrations in olivines of types 4-6 is not correlated with the degree of metamorphism; and mean FeO concentrations of silicates show average increases of 3-5 percent from type 4 to type 6 in each group.

  3. Sphene-centered ocellar texture as a petrological tool to unveil the mechanism facilitating magma mixing

    NASA Astrophysics Data System (ADS)

    Gogoi, Bibhuti; Saikia, Ashima; Ahmad, Mansoor

    2015-04-01

    The sphene-centered ocellar texture is a unique magma mixing feature characterized by leucocratic ocelli of sphene enclosed in a biotite/hornblende-rich matrix (Hibbard, 1991). The ocelli usually consist of plagioclase, K-feldspar and quartz with sphene crystals at its centre. Although geochemical and isotopic data provide concrete evidence for the interaction between two compositionally distinct magmas, the exact processes by which mixing takes place is yet uncertain. So, textural analysis can be used to decipher the behaviour of two disparate magmas during mixing. Presented work is being carried out on the sphene ocelli, occurring in hybrid rocks of the Nimchak Granite Pluton (NGP), to understand its formation while two compositionally different magmas come in contact and try to equilibrate. The NGP is ca. 1 km2in extent which has been extensively intruded by number of mafic dykes exhibiting well preserved magma mixing and mingling structures and textures in the Bathani Volcano-Sedimentary Sequence (BVSS) located on the northern fringe of the Proterozoic Chotanagpur Granite Gneiss Complex (CGGC) of eastern Indian Shield. From petrographic and mineral chemical studies we infer that when basaltic magma intruded the crystallizing granite magma chamber, initially the two compositionally different magmas existed as separate entities. The first interaction that took place between the two phases is diffusion of heat from the relatively hotter mafic magma to the colder felsic one followed by diffusion of elemental components like K and incompatible elements from the felsic to the mafic domain. Once thermal equilibrium was attained between the mafic and felsic melts, the rheological contrasts between the two phases were greatly reduced. This allowed the felsic magma to back-vein into the mafic magma. The influx of back-veined felsic melt into the mafic system disrupted the equilibrium conditions in the mafic domain wherein minerals like amphibole, plagioclase and biotite

  4. Ca-Eskola incorporation in clinopyroxene: limitations and petrological implications for eclogites and related rocks

    NASA Astrophysics Data System (ADS)

    Schroeder-Frerkes, F.; Woodland, A. B.; Uenver-Thiele, L.; Klimm, K.; Knapp, N.

    2016-12-01

    Clinopyroxene is an essential mineral in eclogitic rocks. It commonly contains minor amounts of the defect-bearing Ca-Eskola (CaEs, Ca0.5□0.5AlSi2O6) component, with higher concentrations generally considered to indicate a high-pressure origin at least within the coesite stability field. Changes in pressure and temperature conditions can lead to exsolution of this component as a free SiO2 phase, which may have a number of petrological implications. This makes it important to understand the factors that maximize CaEs incorporation in clinopyroxene. We have undertaken a series of experiments at high pressures and temperatures (4-10 GPa and 1000-1350 °C) to further investigate the systematics of CaEs incorporation in eclogite-like clinopyroxene and the factors responsible for maximizing CaEs contents. Two simple chemical systems were chosen that allow unambiguous interpretation of the results: (1) CMAS + H2O and (2) two compositions in the NCMAS system. All experimental products contained clinopyroxene and garnet along with either a free SiO2 phase or a silicate melt. Coexisting garnet is grossular-rich, generally with X gr ≥ 0.67. Compositional variations are attributable to the presence or absence of melt and changes in modal amounts of garnet at different pressure-temperature conditions. Even small amounts of H2O lower the solidus temperature and the presence of a melt reduces the SiO2 activity, which destabilizes the CaEs component in clinopyroxene. The CaEs and the Ca-Tschermaks (CaTs, CaAl2SiO6) components in clinopyroxene decrease with increasing jadeite mole fraction, which is also a function of pressure and bulk Al content. Modeling X-ray powder diffraction data yields a molar volume for the CaEs endmember of V CaEs = 60.87(63) cm3, which reasonably agrees with a literature value that was estimated from natural samples. In the presence of coexisting coesite, the CaEs and CaTs do not vary independently of each other, being controlled by the internal

  5. Petrology and petrogenesis of the Eocene Volcanic rocks in Yildizeli area (Sivas), Central Anatolia, Turkey

    NASA Astrophysics Data System (ADS)

    Doğa Topbay, C.; Karacık, Zekiye; Genç, S. Can; Göçmengil, Gönenç

    2015-04-01

    Yıldızeli region to the south of İzmir Ankara Erzincan suture zone is situated on the large Sivas Tertiary sedimentary basin. After the northern branch of the Neotethyan Ocean was northerly consumed beneath the Sakarya Continent, a continent - continent collision occurred between the Anatolide- Tauride platform and Pontides and followed a severe intermediate magmatism during the Late Cretaceous- Tertiary period. This created an east-west trending volcanic belt along the whole Pontide range. In the previous studies different models are suggested for the Eocene volcanic succession such as post-collisional, delamination and slab-breakoff models as well as the arc model for its westernmost parts. We will present our field and geochemical data obtained from the Yıldızeli and its surroundings for its petrogenesis, and will discuss the tectonic model(s) on the basis of their geochemical/petrological aspects. Cenozoic volcanic sequences of Yıldızeli region which is the main subject of this study, overlie Pre-Mesozoic crustal meta-sedimentary group of Kırşehir Massif, Ophiolitic mélange and Cretaceous- Paleocene? flysch-like sequences. In the northern part of Yıldızeli region, north vergent thrust fault trending E-W seperates the ophiolitic mélange complex from the Upper Cretaceous-Paleocene and Tertiary formations. Volcano-sedimentary units, Eocene in age, of the Yıldızeli (Sivas-Turkey) which are intercalated with sedimentary deposits related to the collision of Anatolide-Tauride and a simultaneous volcanic activity (i.e. the Yıldızeli volcanics), exposed throughout a wide zone along E-W orientation. Yıldızeli volcanics consist of basalts, basaltic-andesites and andesitic lavas intercalated flow breccias and epiclastic, pyroclastic deposits. Basaltic andesite lavas contain Ca-rich plagioclase + clinopyroxene ± olivine with minor amounts of opaque minerals in a matrix comprised of microlites and glass; andesitic lavas are generally contain Ca

  6. Geochemical work of the Geochemistry and Petrology Branch U.S. Geological Survey

    USGS Publications Warehouse

    Ingerson, E.

    1954-01-01

    The current geochemical work of the Geochemistry and Petrology Branch of the U.S. Geological Survey is outlined under the headings of geochemical compilations, laboratory projects, and field-laboratory projects. Some thirty-seven active projects are described. Six others are mentioned which are planned for the near future. The importance and value of cooperative projects and the "team approach" are emphasized. The hope is expressed that more such projects can be undertaken; also, that summaries of geochemical work under way elsewhere will be published soon for the advancement and better coordination of geochemical research. ?? 1954.

  7. Distribution of terrestrial age and petrologic type of meteorites from western Libya

    SciTech Connect

    Jull, A.J.T.; Donahue, D.J. ); Wlotzka, F.; Palme, H. )

    1990-10-01

    A group of 54 meteorites have been recovered from Daraj, Western Libya. After assessment of pairing of samples, using petrologic criteria, {sup 14}C terrestrial ages were obtained on 13 samples selected from 9 different fall events. Eleven of the ages range from 3,500 to 7,600 years, with only two samples having ages in excess of 10,000 years. The cut-off in ages may be related to the timing of climatic changes in the Hammadah al Hamra.

  8. Spinel cataclasites in 15445 and 72435 - Petrology and criteria for equilibrium

    NASA Technical Reports Server (NTRS)

    Baker, M. B.; Herzberg, C. T.

    1980-01-01

    The problem of establishing the existence of equilibrium among the coexisting phases in the rock is addressed by presenting petrographic and mineral chemistry data on a new spinel cataclasite from 15445 (clast H) and data more extensive than those previously available on two clasts in 72435. Criteria useful in reconstructing the original petrology of these and other spinel cataclasites are analyzed by considering equilibrium among the different phases, that is, the mono- or polymict nature of these cataclasized samples. Finally, the role of impact processes in disturbing the equilibria is discussed.

  9. The Compositional Classification of Chondrules and the Petrologic Type of an Especially Primitive H Chondrite

    NASA Astrophysics Data System (ADS)

    Sears, D. W. G.; Huang, S.; Benoit, P. H.

    1993-07-01

    While LL chondrites of petrologic type <3.4 are relatively common, it has been only recently that a few H chondrites of type <3.4 have been reported. One of them is the heavily weathered Roosevelt County 075 [1]. Weathering and the lack of equilibration make classification uncertain, but it is probably an H chondrite. Weathering also makes it very difficult to assign a petrologic type. For example, removal of the weathering products by acid washing increased the TL sensitivity of RC075 by a factor of ~7, equivalent to a change in petrologic type estimate from 3.0 to 3.3, a major difference. The compositional classification scheme for chondrules [2,3] summarizes considerably more information than previous schemes [4-6], not least being that it tracks metamorphic effects as well as more thoroughly monitoring primary chondrule differences. It is also very easy to apply and almost 100% of the chondrules can be classified. As an example of its utility, we here show that application of the scheme to the chondrules in RC075 provides the best means of determining the petrologic type of this highly weathered, but very important, unequilibrated chondrite. The compositional classification scheme for chondrules divides them into eight classes (A1, A2, A3, A4, A5, B1, B2, B3) on the basis of the composition of the two major phases (phenocrysts and mesostasis) [2,3]. Among the changes that occur during metamorphism, olivines lose CaO and acquire uniform FeO, while the mesostases acquire oligoclase compositions having originally included compositions that were SiO2 rich (the B series), CaO rich (the A series), and Na2O rich (A5). These changes give rise to CL properties that can be used as an alternative to microprobe analysis and which, like microprobe data, are insensitive to weathering. Thus we were able to assign all of the almost 100 chondrules present in a 7 x 5-mm section of RC075 to compositional classes. The results are shown in Fig. 1, along with similar data from [3

  10. Sill genesis in the Paleoproterozoic tectonic evolution of the Onega Trough, Baltic shield

    NASA Astrophysics Data System (ADS)

    Poleshchuk, A. V.

    2011-07-01

    This study considers the role of sill genesis in the tectonic evolution of the Onega Trough during the Middle to Late Paleoproterozoic (Jatulian-Vepsian). The evolution of the Onega Trough is divided into three stages: pre-sill, or preparatory, subsynchronous, and post-sill. Sill magmatism manifested itself most completely at the subsynchronous stage of the evolution of the Onega Trough within the initial, principal, and final phases of sill genesis. Sill formation followed the stage of regional downwarping of the area reaching its maximum during the Early Ludicovian. Paragenesis of sills and high carbon shungite rocks was accompanied by the formation of peperites, while sills influenced the structure of the host rocks. A model reflecting the regular patterns of manifestations of sill genesis identified in the Onega Trough has been proposed.

  11. Scale-invariant perturbations from null-energy-condition violation: A new variant of Galilean genesis

    NASA Astrophysics Data System (ADS)

    Nishi, Sakine; Kobayashi, Tsutomu

    2017-03-01

    We propose a novel branch of the Galilean genesis scenario as an alternative to inflation, in which the Universe starts expanding from Minkowski in the asymptotic past with a gross violation of the null energy condition (NEC). This variant, described by several functions and parameters within the Horndeski scalar-tensor theory, shares the same background dynamics with the existing genesis models, but the nature of primordial quantum fluctuations is quite distinct. In some cases, tensor perturbations grow on superhorizon scales. The tensor power spectrum can be red, blue, or scale invariant, depending on the model, while scalar perturbations are nearly scale invariant. This is in sharp contrast to typical NEC-violating cosmologies, in which a blue tensor tilt is generated. Though the primordial tensor and scalar spectra are both nearly scale invariant as in the inflationary scenario, the consistency relation in our variant of Galilean genesis is nonstandard.

  12. From microscope to mountain belt: 150 years of petrology and its contribution to understanding geodynamics, particularly the tectonics of orogens

    NASA Astrophysics Data System (ADS)

    Brown, M.

    2001-09-01

    Thirty-five years ago the introduction of the plate tectonics paradigm led to a new understanding of orogeny. Subsequently, the development of advanced instruments for remote collection of information and for analysis of elemental and isotopic composition of materials, and the increases in computing power have enabled an unprecedented number of high-precision data about the Earth to be collected, analyzed, modelled and displayed. Within this revolution in global tectonics, the metamorphic petrologist has developed methods to unravel the depth, thermal, temporal and deformational history of orogens using detailed observations at map, hand sample and thin-section scales in combination with elemental and isotope data, and using inverse and forward modelling. Two exciting new directions in metamorphic petrology in relation to geodynamics concern the kinship between earthquakes and metamorphic reactions in subduction zones, and the petrology of the Earth's mantle. Evidence of the changes in pressure ( P) and temperature ( T) in the Earth's crust and upper mantle during the break up, movement, and collision of pieces of the continental lithosphere is sporadically recorded by the mineralogy and microstructures preserved in rocks exhumed to the surface. Better calibration of phase equilibria, the use of internally-consistent thermodynamic data sets and the development of techniques to retrieve close-to-peak P-T conditions from metamorphic rocks have yielded more precise P-T data that enhance our ability to characterize the path followed by individual rocks in P-T space. An improved ability to date segments of the P-T path, and to separate the length of time associated with the prograde (increasing T) evolution from the age of close-to-peak P-T conditions has enabled better understanding of the rates and processes involved in lithosphere thickening. At the same time, better constraints on the retrograde thermal history have contributed to our knowledge of the several

  13. Stratigraphy, petrology, and structure of the Pingston terrane, Mount Hayes C-5 and C-6 quadrangles, eastern Alaska Range, Alaska

    NASA Astrophysics Data System (ADS)

    Nokleberg, W. J.; Schwab, C. E.; Miyaoka, R. T.; Buhrmaster, C. L.

    Recent field, petrologic, and structural studies of the Pingston terrane in the Mount Hayes C-5 and C-6 quandrangles reveal that in this area the terrane: (1) has a highly distinctive stratigraphy, age, petrology (relict textures, relict minerals, and metamorphic facies), and structure; and (2) differs markedly from that described in previous studies. These more recent studies indicate that the major rock types, in order of decreasing abundance, are meta-andesite, metadacite and metarhyodacite flows and (or) tuff, metabasalt, metagabbro, metavolcanic graywacke, metagray-wacke, metasiltstone, metaquartzite or metachert, and very sparse marble. The general petrography of the major rock units in the Pingston terrane is given.

  14. The GENESIS Mission: Solar Wind Isotopic and Elemental Compositions and Their Implications

    NASA Astrophysics Data System (ADS)

    Wiens, R. C.; Burnett, D. S.; McKeegan, K. D.; Kallio, A. P.; Mao, P. H.; Heber, V. S.; Wieler, R.; Meshik, A.; Hohenberg, C. M.; Mabry, J. C.; Gilmour, J.; Crowther, S. A.; Reisenfeld, D. B.; Jurewicz, A.; Marty, B.; Pepin, R. O.; Barraclough, B. L.; Nordholt, J. E.; Olinger, C. T.; Steinberg, J. T.

    2008-12-01

    The GENESIS mission was a novel NASA experiment to collect solar wind at the Earth's L1 point for two years and return it for analysis. The capsule crashed upon re-entry in 2004, but many of the solar-wind collectors were recovered, including separate samples of coronal hole, interstream, and CME material. Laboratory analyses of these materials have allowed higher isotopic precision than possible with current in-situ detectors. To date GENESIS results have been obtained on isotopes of O, He, Ne, Ar, Kr, and Xe on the order of 1% accuracy and precision, with poorer uncertainty on Xe isotopes and significantly better uncertainties on the lighter noble gases. Elemental abundances are available for the above elements as well as Mg, Si, and Fe. When elemental abundances are compared with other in situ solar wind measurements, agreement is generally quite good. One exception is the Ne elemental abundance, which agrees with Ulysses and Apollo SWC results, but not with ACE. Neon is of particular interest because of the uncertainty in the solar Ne abundance, which has significant implications for the standard solar model. Helium isotopic results of material from the different solar wind regimes collected by GENESIS is consistent with isotopic fractionation predictions of the Coulomb drag model, suggesting that isotopic fractionation corrections need to be applied to heavier elements as well when extrapolating solar wind to solar compositions. Noble gas isotopic compositions from GENESIS are consistent with those obtained for solar wind trapped in lunar grains, but have for the first time yielded a very precise Ar isotopic result. Most interesting for cosmochemistry is a preliminary oxygen isotopic result from GENESIS which indicates a solar enrichment of ~4% in 16O relative to the planets, consistent with a photolytic self-shielding phenomenon during solar system formation. Analyses of solar wind N and C isotopes may further elucidate this phenomenon. Preliminary results

  15. Genesis Contingency Planning and Mishap Recovery: The Sample Curation View

    NASA Technical Reports Server (NTRS)

    Stansbery, E. K.; Allton, J. H.; Allen, C. C.; McNamara, K. M.; Calaway, M.; Rodriques, M. C.

    2007-01-01

    Planning for sample preservation and curation was part of mission design from the beginning. One of the scientific objectives for Genesis included collecting samples of three regimes of the solar wind in addition to collecting bulk solar wind during the mission. Collectors were fabricated in different thicknesses for each regime of the solar wind and attached to separate frames exposed to the solar wind during specific periods of solar activity associated with each regime. The original plan to determine the solar regime sampled for specific collectors was to identify to which frame the collector was attached. However, the collectors were dislodged during the hard landing making identification by frame attachment impossible. Because regimes were also identified by thickness of the collector, the regime sampled is identified by measuring fragment thickness. A variety of collector materials and thin films applied to substrates were selected and qualified for flight. This diversity provided elemental measurement in more than one material, mitigating effects of diffusion rates and/or radiation damage. It also mitigated against different material and substrate strengths resulting in differing effects of the hard landing. For example, silicon crystal substrates broke into smaller fragments than sapphire-based substrates and diamond surfaces were more resilient to flying debris damage than gold. The primary responsibility of the curation team for recovery was process documentation. Contingency planning for the recovery phase expanded this responsibility to include not only equipment to document, but also gather, contain and identify samples from the landing area and the recovered spacecraft. The team developed contingency plans for various scenarios as part of mission planning that included topographic maps to aid in site recovery and identification of different modes of transport and purge capability depending on damage. A clean tent, set-up at Utah Test & Training Range

  16. Clues for genesis of magnetic field structure of Mercury

    NASA Astrophysics Data System (ADS)

    Hiremath, K. M.

    2012-07-01

    Recent space observations suggest that Mercury inherits a weak and predominantly large-scale steady dipole like magnetic field structure. Present popular paradigm is to invoke most promising geodynamo like phenomenon that requires the main ingredients such as either a full or partial convection of the interior and fast rotation such that magnetic (Lorentz) and Coriolis forces are of similar order of magnitudes. Hence, the ratio of Lorentz to Coriolis force, called the Elsasser number Λ, must be order of unity. Contrary to the expectation, Mercury rotates so slow that Elsasser number turns out to be << 1. There are also other alternative models to explain genesis of magnetic field structure of Mercury. With the observed constraint of Mercury's atmospheric magnetic field structure, internal magnetic field structure is obtained as a solution of magnetic diffusion equation in the core and a combined multipolar (dipole and quadrupole like magnetic field structures embedded in the uniform field) solution of a current free like magnetic field structure in the mantle and in the atmosphere. Magnetic diffusion time scales are estimated to be ˜ billion years suggesting that present day magnetic field structure might be of primordial origin. In order to reconcile with the experimental fact that, as temperature of Mercury's iron core is above Curie temperature and primordial magnetic field structure must be non-existent, it is proposed that permanency of such a large-scale magnetic field structure of the planet is attained during Mercury's early evolutionary history of heavy bombardments by the asteroids and comets leaving their imprints as craters on this planet. That means the solar system bodies that have heavy bombardments with high density craters during the early epochs of such catastrophic events should have strong magnetic field structures. Is this hypothesis universal? Can this hypothesis gives some clues regarding presence or absence of magnetic field structure of

  17. Rockyhock and Kimbel Carolina Bays: Extraterrestrial Impact or Terrestrial Genesis?

    NASA Astrophysics Data System (ADS)

    Lecompte, M. A.; Branch, B. D.; Barnes, L.; Hall, C.

    2009-12-01

    Evidence for the harsh climate prevalent during the Last Glacial Maximum (LGM) are seen in topographical features visible south of the ice sheet margin in the uplands and coastal regions of the southeastern United States. Among the features attributed to ice age climate are numerous elliptical, shallow depressions called collectively Carolina Bays, hypothesized to have been formed by “blow outs” of loose sediment by the strong, sustained winds and arid, cold climate characteristic of glacial epochs (Raisz, 1934, Johnson, 1942 and Kaczorowski, 1977). This view eclipsed the 1933 proposition by Melton and Schriever, and expanded by Prouty (1934, 1953), that extraterrestrial debris produced by an aerial meteorite or comet explosion in the vicinity of the Great Lakes during the late Pleistocene formed the bays. 12,900 years ago, post-LGM warming was interrupted by a return to a glacial climate that persisted for over 1,000 years. The events precipitating the cooling, known as the Younger Dryas (YD), are the subject of debate. Recently Firestone et. al. (2007) proposed that an impact in the Laurentide ice sheet by a fragmented comet might have simultaneously initiated the YD and formed the Carolina Bays. Carbon 14 dating and pollen analysis of core samples taken from Rockyhock Bay, in Chowan County, NC, by Whitehead (1980) indicate a pre-YD genesis. However, a number of the bays have been found to contain materiel associated with extraterrestrial impacts including carbon and magnetic spherules, glass-like carbon, charcoal and nanodiamonds (Firestone, et. al. 2007). The discoveries reinvigorated the debate over the bay’s origins. Were the bays created by an impact or were they merely receptacles for impact materiel injected into the environment. If created before the YD, the bays would have experienced episodic post-formation modification due to cold, dry, windy periods alternating with warm, moist and calmer climatic conditions. Carolina Bays would thus

  18. 78 FR 49507 - Genesis Solar, LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes Request...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-14

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Genesis Solar, LLC; Supplemental Notice That Initial Market- Based Rate...-referenced proceeding of Genesis Solar, LLC's application for market-based rate authority, with...

  19. Petrological evidence for non-linear increase of magmatic intrusion rates before eruption at open vent mafic volcanoe

    NASA Astrophysics Data System (ADS)

    Ruth, D. C. S.; Costa Rodriguez, F.

    2015-12-01

    The most active volcanoes on earth erupt in a yearly to decadal time scales, typically erupt mafic magmas and are open-vent systems with prominent degassing plumes (e.g. Mayon, Arenal, Llaima, Etna). Here we investigate the plumbing systems, dynamics, and processes that drive eruptions at these systems. These are key questions for improving hazard evaluation, and better understanding the unrest associated with these types of volcanoes. The petrology and geochemistry from six historical eruptions (1947-2006) of Mayon volcano (Philippines) shows that all lavas are basaltic andesite with phenocrysts of plagioclase + orthopyroxene (Opx) + clinopyroxene. Opx crystals show a variety of compositions and zoning patterns (reverse, normal or complex) with Mg# (= 100 *Mg/[Mg+Fe]) varying from 67 to 81. The simplest interpretation is that the low Mg# parts of the crystals resided on an upper crustal and crystal rich reservoir that was intruded by more primitive magmas from which the high Mg# parts of the crystals grew. Modelling Mg-Fe diffusion in Opx shows that times since magma injection and eruption range from a few days up to 3.5 years in all of the investigated eruptions. The longest diffusion times are shorter than the repose times between the eruptions, which implies that crystal recycling between eruptive events is negligible. This is a surprising result that shows that for each eruption a different part of the evolved crystal-rich plumbing system is activated. This can be due to random intrusion location or an irreversibility of the plumbing system that prevents multiple eruptions from the same crystal-rich part. Moreover, we find that the number of intrusions markedly increases before each eruption in a non-linear manner. Such an increased rate of intrusions with time might reflect non-linear rheological properties of the crystal-rich system, of the enclosing rocks, or the non-linear evolution of crystal-melt reaction-dissolution fronts during magma intrusions.

  20. Petrologic evolution of CM chondrites: The difficulty of discriminating between nebular and parent-body effects. [Abstract only

    NASA Technical Reports Server (NTRS)

    Kerridge, J. F.; Mcsween, H. Y., Jr.; Bunch, T. E.

    1994-01-01

    We wish to draw attention to a major controversy that has arisen in the area of CM-chondrite petrology. The problem is important because its resolution will have profound implications for ideas concerning nebular dynamics, gas-solid interactions in the nebula, and accretionary processes in the nebula, among other issues. On the one hand, cogent arguments have been presented that 'accretionary dust mantles,' were formed in the solar nebula prior to accretion of the CM parent asteroid(s). On the other hand, no-less-powerful arguments have been advanced that a significant fraction of the CM lithology is secondary, produced by aqueous alteration in the near-surface regions of an asteroid-sized object. Because most, if not all, CM chondrites are breccias, these two views could coexist harmoniously, were it not for the fact that some of the coarse-grained lithologies surrounded by 'accretion dust mantles' are themselves of apparently secondary origin. Such an observation must clearly force a reassessment of one or both of the present schools of thought. Our objective here is to stimulate such a reassessment. Four possible resolutions of this conflict may be postulated. First, perhaps nature found a way of permitting such secondary alteration to take place in the nebula. Second, maybe dust mantles could form in a regolith, rather than a nebular, environment. Third, it is possible that dust mantles around secondary lithologies are different from those around primary lithologies. Finally, perhaps formation of CM chondrites involved a more complex sequence of events than visualized so far, so that some apparently 'primary' processes postdated certain 'secondary' processes.

  1. Mineralogy, petrology, and chronology of the lunar granulitic breccias

    NASA Astrophysics Data System (ADS)

    Hudgins, Jillian Amy

    Before the return of the Apollo and Luna samples, many basic geological questions about the Moon remained unanswered. The study of returned samples, in addition to remote sensing data and the growing collection of meteorites has revealed that the Moon is a geologically complex body with a history dominated by impact events. Lunar meteorites provide samples of the crust far removed from the Apollo landing sites and are probably more representative of the average lunar crust. SaU 300 was previously misclassified as an anorthositic regolith breccia. Here, I reclassify it as a polymict crystalline impact-melt breccia with an anorthositic norite bulk composition. SaU 300 is a new meteorite that is unpaired with any of the currently known lunar meteorite samples. The main objective of this study was to gain a better understanding of the early evolution of the Moon by studying some of the oldest samples available: the granulitic breccias. The following samples were studied: Apollo samples 60035, 77017, 78155, and 79215 and paired meteorites NWA 3163/4881/4483. Granulitic breccias exhibit poikiloblastic to granoblastic matrix textures and occur as individual rocks and as fragments in impact-melt rocks, the regolith, and in lunar meteorites. These rocks contain 70 -- 80% anorthite, low concentrations of incompatible trace elements, and moderately high concentrations of siderophile elements. Their history was dominated by impact events and thermal metamorphism. Matrix pyroxenes in the granulitic breccias last equilibrated at ˜1050+/-50°C. 40Ar/39Ar data reveal that 60035, 77017, and 78155 have peak metamorphic ages of 4.1 Ga, while 79215 has a peak metamorphic age of 3.9 Ga. NWA 3163 has a peak metamorphic age of 3.3 Ga. Samples 60035, 77017, and NWA 4881 were partially reset by low temperature heating events following metamorphism. Granulitic breccias have been described as "homogeneous on a millimetre scale" throughout the literature. Although they appear to be

  2. Mineralogy of Apollo 15415 ?genesis rock' - Source of anorthosite on moon.

    NASA Technical Reports Server (NTRS)

    Steele, I. M.; Smith, J. V.

    1971-01-01

    Results of electron microprobe analyses of plagioclase points and pyroxene grains of Apollo 15415 ?genesis rock.' It is pointed out that no evidence of cumulate textures has yet appeared to support suggestions of extensive crystal-liquid differentiation producing an anorthositic crust or a lunar crust composed of a mixture of plagioclase-rich rock, basalts and minor ultramafic material, which require that plagioclase crystals float in a basaltic liquid. The plagioclase in 15415 does not show cumulate texture either. It is noted that it remains to be seen whether rock 15415 is correctly named the ?genesis rock.'

  3. Decontaminating Solar Wind Samples with the Genesis Ultra-Pure Water Megasonic Wafer Spin Cleaner

    NASA Technical Reports Server (NTRS)

    Calaway, Michael J.; Rodriquez, M. C.; Allton, J. H.; Stansbery, E. K.

    2009-01-01

    The Genesis sample return capsule, though broken during the landing impact, contained most of the shattered ultra-pure solar wind collectors comprised of silicon and other semiconductor wafers materials. Post-flight analysis revealed that all wafer fragments were littered with surface particle contamination from spacecraft debris as well as soil from the impact site. This particulate contamination interferes with some analyses of solar wind. In early 2005, the Genesis science team decided to investigate methods for removing the surface particle contamination prior to solar wind analysis.

  4. Petrological imaging of an active pluton beneath Cerro Uturuncu, Bolivia

    NASA Astrophysics Data System (ADS)

    Muir, Duncan D.; Blundy, Jon D.; Hutchinson, Michael C.; Rust, Alison C.

    2014-03-01

    Uturuncu is a dormant volcano in the Altiplano of SW Bolivia. A present day ~70 km diameter interferometric synthetic aperture radar (InSAR) anomaly roughly centred on Uturuncu's edifice is believed to be a result of magma intrusion into an active crustal pluton. Past activity at the volcano, spanning 0.89 to 0.27 Ma, is exclusively effusive and almost all lavas and domes are dacitic with phenocrysts of plagioclase, orthopyroxene, biotite, ilmenite and Ti-magnetite plus or minus quartz, and microlites of plagioclase and orthopyroxene set in rhyolitic groundmass glass. Plagioclase-hosted melt inclusions (MI) are rhyolitic with major element compositions that are similar to groundmass glasses. H2O concentrations plotted versus incompatible elements for individual samples describe a trend typical of near-isobaric, volatile-saturated crystallisation. At 870 °C, the average magma temperature calculated from Fe-Ti oxides, the average H2O of 3.2 ± 0.7 wt% and CO2 typically <160 ppm equate to MI trapping pressures of 50-120 MPa, approximately 2-4.5 km below surface. Such shallow storage precludes the role of dacite magma emplacement into pre-eruptive storage regions as being the cause of the observed InSAR anomaly. Storage pressures, whole-rock (WR) chemistry and phase assemblage are remarkably consistent across the eruptive history of the volcano, although magmatic temperatures calculated from Fe-Ti oxide geothermometry, zircon saturation thermometry using MI and orthopyroxene-melt thermometry range from 760 to 925 °C at NNO ± 1 log. This large temperature range is similar to that of saturation temperatures of observed phases in experimental data on Uturuncu dacites. The variation in calculated temperatures is attributed to piecemeal construction of the active pluton by successive inputs of new magma into a growing volume of plutonic mush. Fluctuating temperatures within the mush can account for sieve-textured cores and complex zoning in plagioclase phenocrysts

  5. Sangay volcano, Ecuador: structural development, present activity and petrology

    NASA Astrophysics Data System (ADS)

    Monzier, Michel; Robin, Claude; Samaniego, Pablo; Hall, Minard L.; Cotten, Jo; Mothes, Patricia; Arnaud, Nicolas

    1999-05-01

    Sangay (5230 m), the southernmost active volcano of the Andean Northern Volcanic Zone (NVZ), sits ˜130 km above a >32-Ma-old slab, close to a major tear that separates two distinct subducting oceanic crusts. Southwards, Quaternary volcanism is absent along a 1600-km-long segment of the Andes. Three successive edifices of decreasing volume have formed the Sangay volcanic complex during the last 500 ka. Two former cones (Sangay I and II) have been largely destroyed by sector collapses that resulted in large debris avalanches that flowed out upon the Amazon plain. Sangay III, being constructed within the last avalanche amphitheater, has been active at least since 14 ka BP. Only the largest eruptions with unusually high Plinian columns are likely to represent a major hazard for the inhabited areas located 30 to 100 km west of the volcano. However, given the volcano's relief and unbuttressed eastern side, a future collapse must be considered, that would seriously affect an area of present-day colonization in the Amazon plain, ˜30 km east of the summit. Andesites greatly predominate at Sangay, there being few dacites and basalts. In order to explain the unusual characteristics of the Sangay suite—highest content of incompatible elements (except Y and HREE) of any NVZ suite, low Y and HREE values in the andesites and dacites, and high Nb/La of the only basalt found—a preliminary five-step model is proposed: (1) an enriched mantle (in comparison with an MORB source), or maybe a variably enriched mantle, at the site of the Sangay, prior to Quaternary volcanism; (2) metasomatism of this mantle by important volumes of slab-derived fluids enriched in soluble incompatible elements, due to the subduction of major oceanic fracture zones; (3) partial melting of this metasomatized mantle and generation of primitive basaltic melts with Nb/La values typical of the NVZ, which are parental to the entire Sangay suite but apparently never reach the surface and subordinate

  6. Geochemistry and genesis of behind-arc basaltic lavas from eastern Nicaragua

    NASA Astrophysics Data System (ADS)

    Janoušek, V.; Erban, V.; Holub, F. V.; Magna, T.; Bellon, H.; Mlčoch, B.; Wiechert, U.; Rapprich, V.

    2010-05-01

    The petrology and chemistry of the Behind the Volcanic Front (BVF) lavas from eastern mainland Nicaragua and the adjacent Great Corn Island in the Caribbean Sea illustrate the complex nature of sources and processes operating in such a tectonic setting. The older, Early Miocene (˜ 17 Ma) group of low-Ti (< 1 wt.%) basalts-andesites is characterized by a strong LILE/HFSE depletion. The low-Ti lavas from El Rama and El Bluff areas are interpreted as relics of Early Miocene volcanic arc, largely analogous to the nowadays extinct Coyol arc further west. However, these rocks differ in some parameters from the modern volcanic front lavas, most notably in having lower δ7Li values, Ba/Yb ratios and lower U contents. The younger high-Ti (Ti > 1.5%) lavas, rich in other HFSE as well, are represented both by alkaline (Quaternary trachybasalts: Volcán Azul and Kukra Hill) and subalkaline (basalts-basaltic andesites: Late Miocene, ˜ 11 Ma Great Corn Island and Quaternary, Pearl Lagoon) volcanic rocks. The Late Miocene and Quaternary high-Ti BVF lavas probably represent small-volume decompression melts of a source similar to that of the OIB-like magmas, most likely upwelling asthenosphere having a strong Galápagos mantle imprint. The positive Sr-Nd isotopic correlation indicates an interaction between this OIB component and a depleted lithospheric mantle modified by a subduction-related influx of Sr and, to a lesser extent, other hydrous fluid-mobile elements. However, the rocks show no recognizable influence of the modern subduction. The feeble trace-element (e.g., slightly elevated Ba, K, and Sr at some localities) and a more pronounced Sr-Li isotopic subduction-related signal stems most likely from the Miocene convergence episode. Subduction of the Galápagos hot-spot tracks in Costa Rica produces magmas that can be readily recognized by their elevated Sr isotopic ratios due to seafloor alteration; the Nd isotopic signature remains unaffected. Such a component with

  7. Petrological and seismic precursors of the paroxysmal phase of the last Vesuvius eruption on March 1944

    PubMed Central

    Pappalardo, Lucia; D'Auria, Luca; Cavallo, Andrea; Fiore, Stefano

    2014-01-01

    Abrupt transitions in style and intensity are common during volcanic eruptions, with an immediate impact on the surrounding territory and its population. Defining the factors trigger such sudden shifts in the eruptive behavior as well as developing methods to predict such changes during volcanic crises are crucial goals in volcanology. In our research, the combined investigation of both petrological and seismic indicators has been applied for the first time to a Vesuvius eruption, that of March 1944 that caused the present dormant state of the volcano. Our results contribute to elucidate the evolution of the conduit dynamics that generated a drastic increase in the Volcanic Explosivity Index, associated to the ejection of huge amount of volcanic ash. Remarkably, our study shows that the main paroxysm was announced by robust changes in petrology consistent with seismology, thus suggesting that the development of monitoring methods to assess the nature of ejected juvenile material combined with conventional geophysical techniques can represent a powerful tool for forecasting the evolution of an eruption towards violent behavior. This in turn is a major goal in volcanology because this evidence can help decision-makers to implement an efficient safety strategy during the emergency (scale and pace of evacuation). PMID:25199537

  8. Interactive computer programs for petrologic modeling with extended Q-mode factor analysis

    USGS Publications Warehouse

    Miesch, A.T.

    1976-01-01

    An extended form of Q-mode factor analysis may be used if the row-sums of the data matrix are constant and can be helpful especially in developing and testing petrologic-mixing models for igneous systems. The first step is to represent the sample compositions as unit vectors in M-dimensional space and then to project them into space of fewer dimensions (m) as determined to be appropriate from a factor-variance diagram. Compositions thought to be those of possible end-members in the petrologic system then are represented as vectors in the M-dimensional space and projected into the same space as the sample vectors. If these vectors remain close to unity in length after projection, the corresponding compositions can serve as end-member compositions for the model. After m suitable end-member compositions have been identified, each sample composition is expressed as a mixture of the end-members by computation of the composition loadings. The interactive computer programs presented are useful in these procedures because of the trial-and-error nature of the modeling procedures. ?? 1976.

  9. Quantitative EPMA Compositional Mapping of NWA 2995: Characterization, and Petrologic Interpretation of Mafic Clasts

    NASA Technical Reports Server (NTRS)

    Carpenter, P. K.; Hahn, T. M.; Korotev, R. L.; Ziegler, R. A.; Jolliff, B. L.

    2017-01-01

    We present the first fully quantitative compositional maps of lunar meteorite NWA 2995 using electron microprobe stage mapping, and compare selected clast mineralogy and chemistry. NWA 2995 is a feldspathic fragmental breccia containing numerous highland fine grained lithologies, including anorthosite, norite, olivine basalt, subophitic basalt, gabbro, KREEP-like basalt, granulitic and glassy impact melts, coarse-grained mineral fragments, Fe-Ni metal, and glassy matrix [1]. Chips of NWA 2995, representing these diverse materials, were analyzed by INAA and fused-bead electron-probe microanalysis (EPMA); comparison of analytical data suggests grouping of lunar meteorites NWA 2995, 2996, 3190, 4503, 5151, and 5152. The mean composition of NWA 2995 corresponds to a 2:1 mixture of feldspathic and mare material, with approximately 5% KREEP component [2]. Clast mineral chemistry and petrologic interpretation of paired stone NWA 2996 has been reported by Mercer et al. [3], and Gross et al. [4]. This study combines advances in quantitative EPMA compositional mapping and data analysis, as applied to selected mafic clasts in a polished section of NWA 2995, to investigate the origin of mafic lithic components and to demonstrate a procedural framework for petrologic analysis.

  10. Towards Calibrating the Vestan Regolith: Correlating the Petrology, Chemistry and Spectroscopy of Howardites

    NASA Technical Reports Server (NTRS)

    Mittlefehldt, D. W.; Ammannito, E.; Hiroi, T.; De Angelis, S.; Di Iorio, T.; Pieters, C. M.; De Sanctis, C.

    2013-01-01

    The Dawn spacecraft carries a visible and infrared mapping spectrometer (VIR) [1] that has acquired spectra for the wavelength range 0.25-5.0 µm at various spatial resolutions covering much of the vestan surface [2]. Through comparison of VIR spectra with laboratory spectra of howardite, eucrite and diogenite meteorites, the distribution of more diogenite-rich and more eucrite-rich terranes on Vesta have been mapped [3], but these maps are qualitative in nature. The available laboratory spectra are not well-integrated with detailed sample petrology or composition limiting their utility for lithologic mapping. Importantly, howardites are now recognized to come in two subtypes, regolithic and fragmental [4]. The former are breccias assembled in part from true regolith, while the latter have had much less exposure to the space environment. We are attempting to develop a more quantitative basis for mapping the distribution of lithologic types on Vesta through acquiring laboratory spectra on splits of howardites that have been petrologically and chemically characterized [5]. Noble gas analyses have been done on some allowing identification of those howardites that have been exposed in the true regolith of Vesta [6].

  11. Petrological and seismic precursors of the paroxysmal phase of the last Vesuvius eruption on March 1944

    NASA Astrophysics Data System (ADS)

    Pappalardo, Lucia; D'Auria, Luca; Cavallo, Andrea; Fiore, Stefano

    2014-09-01

    Abrupt transitions in style and intensity are common during volcanic eruptions, with an immediate impact on the surrounding territory and its population. Defining the factors trigger such sudden shifts in the eruptive behavior as well as developing methods to predict such changes during volcanic crises are crucial goals in volcanology. In our research, the combined investigation of both petrological and seismic indicators has been applied for the first time to a Vesuvius eruption, that of March 1944 that caused the present dormant state of the volcano. Our results contribute to elucidate the evolution of the conduit dynamics that generated a drastic increase in the Volcanic Explosivity Index, associated to the ejection of huge amount of volcanic ash. Remarkably, our study shows that the main paroxysm was announced by robust changes in petrology consistent with seismology, thus suggesting that the development of monitoring methods to assess the nature of ejected juvenile material combined with conventional geophysical techniques can represent a powerful tool for forecasting the evolution of an eruption towards violent behavior. This in turn is a major goal in volcanology because this evidence can help decision-makers to implement an efficient safety strategy during the emergency (scale and pace of evacuation).

  12. Petrology and Geochemistry of Unbrecciated Harzburgitic Diogenite MIL 07001: A Window Into Vestan Geological Evolution

    NASA Technical Reports Server (NTRS)

    Mittlefehldt, D. W.; Peng, Z. X.; Mertzman, S. A.; Mertzman, K. R.

    2014-01-01

    There is a strong case that asteroid 4 Vesta is the parent of the howardite, eucrite and diogenite (HED) meteorites. Models developed for the geological evolution of Vesta can satisfy the compositions of basaltic eucrites that dominate in the upper crust. The bulk compositional characteristics of diogenites - cumulate harzburgites and orthopyroxenites from the lower crust - do not fit into global magma ocean models that can describe the compositions of basaltic and cumulate eucrites. Recent more detailed formation models do make provision for a more complicated origin for diogenites, but this model has yet to be completely vetted. Compositional studies of bulk samples has led to the hypothesis that many diogenites were formed late by interaction of their parent melts with a eucritic crust, but those observations may alternatively be explained by subsolidus equilibration of trace elements between orthopyroxene and plagioclase and Ca-phosphate in the rocks. Differences in radiogenic Mg-26 content between diogenites and eucrites favors early formation of the former, not later formation. Understanding the origin of diogenites is crucial for understanding the petrologic evolution of Vesta. We have been doing coordinated studies of a suite of diogenites including petrologic investigations, bulk rock major and trace element studies, and in situ trace element analyses of orthopyroxene. Here we will focus on an especially unusual, and potentially key, diogenite, MIL 07001.

  13. Geochemical And Petrological Investigations Of The Representative Cretaceous Bentonite Beds, Wyoming : Tectonic Implications

    NASA Astrophysics Data System (ADS)

    Khandaker, N. I.

    2004-12-01

    Representative bentonite samples were collected from the exposed Cretaceous siliciclastics in Bighorn Basin, north-central Wyoming. Bentonite beds constitute a significant stratigraphic importance with respect to local and regional correlation tool and are associated with the Thermopolis Shale (Lower Cretaceous), Mowry Shale (Lower Cretaceous), and Frontier Formation (Upper Cretaceous). These beds range in thickness from few inches to ten feet and are interbedded with thick cross-bedded sandstone, pebbly sandstone, polymictic conglomerate, siliceous-rippled shale, and lignitic shale. Preliminary petrological and geochemical investigations were carried out to establish a distinctive geochemical signature for each bed. Emphasis was given on the overall distribution of the immobile traces, high refractory elements, and ultrastable heavy mineral components among the selective bentonite beds. The outcome of petrological, bulk, and trace element studies involving multiple bentonite beds indicated a subtle difference in terms of abundance of trace-element and detrital components among the studied samples and can be attributed to the source region characteristics, distinctive diagenetic pathways, and depositional setting. Furthermore, geochemical analyses involving multi-element plots suggest to an evolving source terrain located in close proximity to the bentonite depositional basin.

  14. Petrological and seismic precursors of the paroxysmal phase of the last Vesuvius eruption on March 1944.

    PubMed

    Pappalardo, Lucia; D'Auria, Luca; Cavallo, Andrea; Fiore, Stefano

    2014-09-09

    Abrupt transitions in style and intensity are common during volcanic eruptions, with an immediate impact on the surrounding territory and its population. Defining the factors trigger such sudden shifts in the eruptive behavior as well as developing methods to predict such changes during volcanic crises are crucial goals in volcanology. In our research, the combined investigation of both petrological and seismic indicators has been applied for the first time to a Vesuvius eruption, that of March 1944 that caused the present dormant state of the volcano. Our results contribute to elucidate the evolution of the conduit dynamics that generated a drastic increase in the Volcanic Explosivity Index, associated to the ejection of huge amount of volcanic ash. Remarkably, our study shows that the main paroxysm was announced by robust changes in petrology consistent with seismology, thus suggesting that the development of monitoring methods to assess the nature of ejected juvenile material combined with conventional geophysical techniques can represent a powerful tool for forecasting the evolution of an eruption towards violent behavior. This in turn is a major goal in volcanology because this evidence can help decision-makers to implement an efficient safety strategy during the emergency (scale and pace of evacuation).

  15. Double seismic zone of the Nazca plate in northern Chile: High-resolution velocity structure, petrological implications, and thermomechanical modeling

    NASA Astrophysics Data System (ADS)

    Dorbath, Catherine; Gerbault, Muriel; Carlier, Gabriel; Guiraud, Michel

    2008-07-01

    This paper presents an interdisciplinary study of the northern Chile double seismic zone. First, a high-resolution velocity structure of the subducting Nazca plate has been obtained by the tomoDD double-difference tomography method. The double seismic zone (DSZ) is observed between 80 and 140 km depth, and the two seismic planes is 20 km apart. Then, the chemical and petrologic characteristics of the oceanic lithosphere associated with this DSZ are deduced by using current thermal-petrological-seismological models and are compared to pressure-temperature conditions provided by a numerical thermomechanical model. Our results agree with the common hypothesis that seismicity in both upper and lower planes is related to fluid releases associated with metamorphic dehydration reactions. In the seismic upper plane located within the upper crust, these reactions would affect material of basaltic (MORB) composition and document different metamorphic reactions occurring within high-P (>2.4 GPa) and low-T (<570°C) jadeite-lawsonite blueschists and, at greater depth (>130 km), lawsonite-amphibole eclogite conditions. The lower plane lying in the oceanic mantle can be associated with serpentinite dehydration reactions. The Vp and Vs characteristics of the region in between both planes are consistent with a partially (˜25-30 vol % antigorite, ˜0-10% vol % brucite, and ˜4-10 vol % chlorite) hydrated harzburgitic material. Discrepancies persist that we attribute to complexities inherent to heterogeneous structural compositions. While various geophysical indicators evidence particularly cold conditions in both the descending Nazca plate and the continental fore arc, thermomechanical models indicate that both seismic planes delimit the inner slab compressional zone around the 400°C (±50°C) isotherm. Lower plane earthquakes are predicted to occur in the slab's flexural neutral plane, where fluids released from surrounding metamorphic reactions could accumulate and trigger

  16. Weathering and genesis of Soils from Ellsworth Mountains, East Antarctica

    NASA Astrophysics Data System (ADS)

    Karoline Delpupo Souza, Katia; Schaefer, Carlos Ernesto; Michel, Roberto; Monari, Julia; Machado, Vania

    2015-04-01

    Knowledge on Antarctic soils from the Ellsworth Mountains (EM) are patchy comparatively with Dry Valleys soils from the Transantartic Mountains, and could help understand the genesis of cryogenic soils under extreme dry, cold desert conditions. The EM are a slightly arcuate 350-km-long north-northwest-trending mountain chain is bordered on the west by the polar plateau of West Antarctica and on the east by Ronne Ice Shelf. The range is as much as 90 km wide and constitutes one of the largest areas of exposed bedrock in West Antarctica. The stratigraphic succession in the EM includes strata from Cambriam to Permian in age. The objective of this study is to analyze the properties of soils from EM in order to identify the main factors and processes involved in soil formation under cold desert conditions in Antarctica. The sampling design aimed to represent the different geological substrates (marble-clast conglomerate, graywacke, argillite, conglomerate, black shale, marble and quartzite) as well as altitudinal levels and landforms within the same substrate. We characterized soils from EM regarding their morphological, physics and chemical properties. Soil samples were air dried and passed through 2 mm sieves. After removal of water soluble salts, the samples were submitted to chemical and physical analyses such as: pH in water, potential acidity (H + Al), exchangeable bases, total organic carbon, electric conductivity, soil texture and color. The soils classify, for the most part, in weathering stages 1 to 2. Only in the upper parts of ridges were there traces of soils at weathering stage 3. This indicates that much of the present icefree topography has been overridden by ice within the last few hundred thousand years. Cryoturbation is a widespread phenomenon in this area resulting in intense cryoclastic weathering and patterned ground, forming sorted circles, stripes and gelifluxion lobes. The soil show low horizontation, discrete patches of salt on the surface, and

  17. Genesis of ion-adsorption type REE ores in Thailand

    NASA Astrophysics Data System (ADS)

    Sanematsu, K.; Yoshiaki, K.; Watanabe, Y.

    2012-04-01

    Ion-adsorption type REE deposits, which have been economically mined only in southern China, are predominant supply sources for HREE in the world. The ore bodies consist of weathered granites called ion-adsorption ores. The majority of REE (>50 %) are electrostatically adsorbed onto weathering products in the ores and they can be extracted by ion exchange using an electrolyte solution (e.g., ammonium sulfate solution). Recently the occurrences of ion-adsorption ores have been reported in Indochina, SE Asia. In this study, we discuss geochemical and mineralogical characteristics of parent granites and weathered granites in Thailand in order to reveal the genesis of ion-adsorption ores. Permo-Triassic and Cretaceous-Paleogene granite plutons are distributed from northern Thailand to western Indonesia through eastern Myanmar and Peninsular Malaysia. They are mostly ilmenite-series calcalkaline biotite or hornblende-biotite granites. REE contents of the granites range from 60 to 600 ppm and they are relatively high in Peninsula Thailand. REE-bearing minerals consist mainly of apatite, zircon, allanite, titanite, monazite and xenotime. Some I-type granites contain REE fluorocarbonate (probably synchysite-(Ce)) in cavities and cracks in feldspars and it is the dominant source of REE for ion-adsorption ores because the fluorocarbonate is easily soluble during weathering. In contrast, insoluble monazite and xenotime are not preferable for ion-adsorption ores although they are common ore minerals of placer REE deposits. Weathered granites show REE contents ranging from 60 to 1100 ppm in Thailand because REE are relatively immobile compared with mobile elements (e.g., Na, K, Ca). In the weathered granites, REE are contained in residual minerals and secondary minerals and are adsorbed onto the surface of weathering products. A weathering profile of granite with ion-adsorption type mineralization can be divided into upper and lower parts based on REE enrichment and Ce

  18. Analyzing the influences of two types of El Niño on Tropical Cyclone Genesis with a modified genesis potential index

    NASA Astrophysics Data System (ADS)

    Yang, Yuxing; Yang, Lei; Wang, Faming

    2016-05-01

    To understand the impacts of large-scale circulation during the evolution of El Niño cycle on tropical cyclones (TC) is important and useful for TC forecast. Based on best-track data from the Joint Typhoon Warning Center and reanalysis data from National Centers for Environmental Prediction for the period 1975-2014, we investigated the influences of two types of El Niño, the eastern Pacific El Niño (EP-El Niño) and central Pacific El Niño (CP-El Niño), on global TC genesis. We also examined how various environmental factors contribute to these influences using a modified genesis potential index (MGPI). The composites reproduced for two types of El Niño, from their developing to decaying phases, were able to qualitatively replicate observed cyclogenesis in several basins except for the Arabian Sea. Certain factors of MGPI with more influence than others in various regions are identified. Over the western North Pacific, five variables were all important in the two El Niño types during developing summer (July-August-September) and fall (October-November-December), and decaying spring (April-May-June) and summer. In the eastern Pacific, vertical shear and relative vorticity are the crucial factors for the two types of El Niño during developing and decaying summers. In the Atlantic, vertical shear, potential intensity and relative humidity are important for the opposite variation of EP- and CP-El Niños during decaying summers. In the Southern Hemisphere, the five variables have varying contributions to TC genesis variation during peak season (January-February-March) for the two types of El Niño. In the Bay of Bengal, relative vorticity, humidity and omega may be responsible for clearly reduced TC genesis during developing fall for the two types and slightly suppressed TC cyclogenesis during EP-El Niño decaying spring. In the Arabian Sea, the EP-El Niño generates a slightly positive anomaly of TC genesis during developing falls and decaying springs, but the

  19. Analyzing the influences of two types of El Niño on tropical cyclone genesis with a modified genesis potential index

    NASA Astrophysics Data System (ADS)

    Yang, Yuxing; Yang, Lei; Wang, Faming

    2017-03-01

    To understand the impacts of large-scale circulation during the evolution of El Niño cycle on tropical cyclones (TC) is important and useful for TC forecast. Based on best-track data from the Joint Typhoon Warning Center and reanalysis data from National Centers for Environmental Prediction for the period 1975-2014, we investigated the influences of two types of El Niño, the eastern Pacific El Niño (EP-El Niño) and central Pacific El Niño (CP-El Niño), on global TC genesis. We also examined how various environmental factors contribute to these influences using a modified genesis potential index (MGPI). The composites reproduced for two types of El Niño, from their developing to decaying phases, were able to qualitatively replicate observed cyclogenesis in several basins except for the Arabian Sea. Certain factors of MGPI with more influence than others in various regions are identified. Over the western North Pacific, five variables were all important in the two El Niño types during developing summer (July-August-September) and fall (October-November-December), and decaying spring (April-May-June) and summer. In the eastern Pacific, vertical shear and relative vorticity are the crucial factors for the two types of El Niño during developing and decaying summers. In the Atlantic, vertical shear, potential intensity and relative humidity are important for the opposite variation of EP- and CP-El Niños during decaying summers. In the Southern Hemisphere, the five variables have varying contributions to TC genesis variation during peak season (January-February-March) for the two types of El Niño. In the Bay of Bengal, relative vorticity, humidity and omega may be responsible for clearly reduced TC genesis during developing fall for the two types and slightly suppressed TC cyclogenesis during EP-El Niño decaying spring. In the Arabian Sea, the EP-El Niño generates a slightly positive anomaly of TC genesis during developing falls and decaying springs, but the

  20. Petrologic insights into basaltic volcanism at historically active Hawaiian volcanoes: Chapter 6 in Characteristics of Hawaiian volcanoes

    USGS Publications Warehouse

    Helz, Rosalind L.; Clague, David A.; Sisson, Thomas W.; Thornber, Carl R.; Poland, Michael P.; Takahashi, T. Jane; Landowski, Claire M.

    2014-01-01

    Contributions to our knowledge of the nature of the mantle source(s) of Hawaiian basalts are reviewed briefly, although this is a topic where debate is ongoing. Finally, our accumulated petrologic observations impose constraints on the nature of the summit reservoirs at Kīlauea and Mauna Loa, specifically whether the summit chamber has been continuous or segmented during past decades.

  1. Origin of New Faculty in Sedimentary Petrology at Ph.D.-Granting Universities in the United States and Canada.

    ERIC Educational Resources Information Center

    Thornton, Scott E.

    1981-01-01

    To aid prospective graduate students in sedimentary petrology who wish to teach at colleges or universities, 121 doctoral graduates in this field are traced to their present appointments in higher education. Only 31 percent of these graduates attained this career goal. (Author/WB)

  2. Thermal modeling of the southern Alaska subduction zone: Insight into the petrology of the subducting slab and overlying mantle wedge

    SciTech Connect

    Ponko, S.C.; Peacock, S.M.

    1995-11-10

    This report discusses a two-dimensional thermal model of the southern Alaska subduction zone. This model allows specfic predictions to be made about the pressure-temperature conditions and mineralogy of the subducting oceanic crust and the mantle wedge and assess different petrologic models for the generation of Alaskan arc magmas.

  3. ALTERED RA SIGNALING IN THE GENESIS OF ETHANOL-INDUCED LIMB DEFECTS

    EPA Science Inventory

    Altered RA Signaling in the Genesis of Ethanol-Induced Limb Defects

    Johnson CS(1), Sulik KK(1,2) Hunter, ES III(3)
    (1) Dept of Cell and Developmental Biology, UNC-Chapel Hill (2) Bowles Center for Alcohol Studies, UNC-CH (3) NHEERL, ORD, US EPA, RTP, NC

    Administr...

  4. Argon, Krypton, and Xenon in Three Solar Wind Regimes as Collected by GENESIS

    NASA Astrophysics Data System (ADS)

    Vogel, N.; Baur, H.; Burnett, D. S.; Maden, C.; Wieler, R.

    2011-03-01

    We present new heavy noble gas fluxes and elemental compositions (36Ar/84Kr, 84Kr/132Xe) for the fast, slow, and CME-related Solar Wind as collected by Genesis in order to rule on element fractionation processes during Solar Wind formation.

  5. 75 FR 22838 - Notice of Availability of the Draft Environmental Impact Statement for the Genesis Project...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-30

    ... INFORMATION: Newmont Mining Corporation's Genesis- Bluestar mining operations area is located in northeastern... million ounces of gold from numerous mines over the last 30 years. The proposed action is to expand the... necessary haul roads and access roads, and process 60 million tons of gold-bearing ore. The proposed...

  6. Cellulose Acetate Replica Cleaning Study of Genesis Non-Flight Sample 3CZ00327

    NASA Technical Reports Server (NTRS)

    Kuhlman, K. R.; Schmeling, M.; Gonzalez, C. P.; Allton, J. H.; Burnett, D. S.

    2014-01-01

    The Genesis mission collected solar wind and brought it back to Earth in order to provide precise knowledge of solar isotopic and elemental compositions. The ions in the solar wind were stopped in the collectors at depths on the order of 10 to a few hundred nanometers. This shallow implantation layer is critical for scientific analysis of the composition of the solar wind and must be preserved throughout sample handling, cleaning, processing, distribution, preparation and analysis. We are working interactively with the community of scientists analyzing Genesis samples, using our unique laboratory facilities -- and, where needed, our unique cleaning techniques -- to significantly enhance the science return from the Genesis mission. This work is motivated by the need to understand the submicron contamination on the collectors in the Genesis payload as recovered from the crash site in the Utah desert, and -- perhaps more importantly -- how to remove it. That is, we are evaluating the effectiveness of the wet-chemical "cleaning" steps used by various investigators, to enable them to design improved methods of stripping terrestrial contamination from surfaces while still leaving the solar-wind signal intact.

  7. Engendering Proof Attitudes: Can the Genesis of Mathematical Knowledge Teach Us Anything?

    ERIC Educational Resources Information Center

    Almeida, Dennis

    2003-01-01

    Suggests that there is continued poverty in student understanding of proof. Reports on how proof attitudes could be inculcated in students by offering them a course design that is somewhat faithful to the historical genesis of modern mathematics. Contends that such a design can enable students to discover a sense of proof for themselves. (Contains…

  8. Simulation of the Genesis of Hurricane Javier (2004) in the Eastern Pacific

    NASA Technical Reports Server (NTRS)

    Braun, Scott

    2005-01-01

    NASA is preparing for the Tropical Cloud Systems and Processes (TCSP) field experiment in July 2005, a joint effort with NOAA to study tropical cloud systems and tropical cyclone genesis in the Eastern Pacific. A major thrust of the TCSP program is the improvement of the understanding and prediction of tropical cyclone genesis, intensity, motion, rainfall potential, and landfall impacts using remote sensing and in-situ data, as well as numerical modeling, particularly as they relate to the three phases of water. The Eastern Pacific has the highest frequency of genesis events per unit area of any region worldwide. African easterly waves, mesoscale convective systems (MCSs), and orographic effects are thought to play roles in the genesis of tropical cyclones there. The general consensus is that tropical depressions form in association with one or more mid-level, mesoscale cyclonic vortices that are generated within the stratiform region of the MCS precursors. To create the warm core tropical depression vortex, however, the midlevel cyclonic circulation must somehow extend down to the surface and the tangential winds must attain sufficient strength (-10 m s- ) to enable the wind-induced surface heat exchange to increase the potential energy of the boundary layer air.

  9. The First Year of Solar-Wind Data From the GENESIS Mission

    NASA Astrophysics Data System (ADS)

    Wiens, R. C.; Barraclough, B. L.; Steinberg, J. T.; Reisenfeld, D. B.; Neugebauer, M.; Burnett, D. S.

    2002-12-01

    The GENESIS mission was launched in August, 2001, and has been in an L1 halo orbit for over a year. The primary purpose of the mission is to collect solar-wind samples that will be returned to Earth in 2004 for high-precision isotopic and elemental analyses. GENESIS uses conventional ion and electron spectrometers to record solar-wind conditions during collection, and to make real-time determinations of the solar-wind regimes to facilitate collection of separate samples of interstream (IS), coronal hole (CH), and coronal mass ejection (CME) flows. Of particular interest is the use of a bi-directional electron (BDE) index to determine the presence of CMEs. And although GENESIS lacks a magnetometer, the field vector, with sign ambiguity, is determined by the electron direction, and matches other spacecraft magnetometer data well. GENESIS in-situ data and on-board regime determinations are available on the web. The data from Fall, 2001 were characterized by numerous CME regimes (comprising 32% of the time in the 4th quarter, based on the on-board algorithm), with little CH flow (only 2%). A strong CH flow was observed every solar rotation from mid-January through late May. June was quiet, nearly all IS flow. The first and second quarters of 2002 were approximately 28% CME flow, with CH flow dropping from 18% to 6%. The discovery of unexpectedly noticeable BDE signals during CH flows at 1 AU (Steinberg et al., 2002) caused us early on to modify our regime selection algorithm to accommodate these. The on-board algorithm intentionally errs on the side of overestimating CME flows in order to keep the CH sample more pure. Comparisons have been made of various compositional parameters determined by Genesis (Barraclough et al., this meeting) and by ACE SWICS (Reisenfeld et al., this meeting) for times corresponding to the Genesis collection periods for each of the three regimes. The Genesis L1 halo orbit is ~0.8 x 0.25 million km radius, somewhat larger than the ~0.3 x 0

  10. The role of a convective burst in the genesis of typhoon Hagupit (2008)

    NASA Astrophysics Data System (ADS)

    Murata, Akihiko

    2013-05-01

    This study explores the effects of the mesoscale descent associated with a convective burst during the genesis of typhoon Hagupit (2008), based on a high-resolution cloud-resolving numerical simulation. The simulation result captures the synoptic-scale circulation surrounding the pre-Hagupit depression and the evolution of the storm. A burst of intense deep convection occurs about 1 day before the genesis of Hagupit. After the convective burst, temperature deviation near the center of the depression increases in the lower troposphere. This warming contributes to a drop in the central pressure of the depression and hence to the beginning of the so-called system-scale intensification. In addition, the low-level warming tends to inhibit vertical motion by acting as a lid. Horizontal flow is therefore dominant in the boundary layer; thereby, the air can efficiently gain energy from the sea surface. Increased energy in the boundary layer air feeds intense deep convection near the center of the depression just before the genesis time. These results are consistent with a previous observational study. Tangential momentum budget analysis demonstrates that, just before the genesis time, actual tendency of tangential velocity has larger values throughout the depth of the troposphere, indicating the importance of the deep-layer spin-up of the depression. These large values are attributed to the upward transport of tangential momentum by intense deep convection. In contrast, when the convective burst occurs about 1 day before the genesis time, positive actual tendency is confined to the lower troposphere because of smaller upward transport of tangential momentum.

  11. Bedform genesis and evolution in bedrock substrates: a new experimental approach

    NASA Astrophysics Data System (ADS)

    Parsons, D. R.; Yin, N.; Peakall, J.

    2014-12-01

    Most previous studies on the genesis and evolution of bedforms have focused on aggradational bedforms within cohesionless sediments, with very few investigations that concern either erosive bedform genesis and evolution or bedrock channel abrasion processes. The study presented here details experiments that involve the genesis and formation of erosional bedform features within natural (soft clay) cohesive sediment beds and analogue bedrock substrates by modelling clay under the effect of both open-channel plain water flows, and sediment-laden flows. A new approach without using plaster-of-Paris or real bedrock developed provides a feasible method to simulate the genesis and evolution of the erosional bedforms in cohesive sediment beds and sculpted forms in bedrock channels on relatively short time-scales in the laboratory by using a realistic substrate substitute.A series of flume experiments are presented herein where the undrained shear strength of two different kinds of substrate material is systematically varied under constant flow conditions. Experiments using plain water flow indicated that erosive bedforms in cohesive sediment substrate cannot be produced only under the effect of sediment-free flow. Particulate-laden flows do form erosional bedforms in both kinds of clay beds and the shear strength of the bed material plays a key role in determining the diversity of erosional features forming on such substrates. Optimisation of modelling clay beds has enabled us to successfully replicate a suite of bedrock bedforms, including potholes, flutes, longitudinal furrows, etc., that have clear equivalents to those observed in bedrock rivers and contributed to investigate the genesis and evolution process of them and explore the flow structures within and above them in experimental analogue bedrock substrate for the first time.

  12. Teaching Mineralogy, Petrology and Geochemistry in the 21st Century: Instructional Resources for Geoscience Faculty

    NASA Astrophysics Data System (ADS)

    Mogk, D. W.; Beane, R. J.; Whitney, D. L.; Nicolaysen, K. E.; Panero, W. R.; Peck, W. H.

    2011-12-01

    Mineralogy, petrology and geochemistry (MPG) are pillars of the geoscience curriculum because of their relevance in interpreting Earth history and processes, application to geo-hazards, resources, and environmental issues, and contributions to emerging fields such as geology and human health. To keep faculty current in scientific advances in these fields, and in modern instructional methods, the On the Cutting Edge program convened a workshop at the University of Minnesota in August, 2011. This workshop builds on the previous 15 year's work that has been focused on identifying, aggregating, and developing high-quality collections of teaching activities and related resources, and in building a community of scholars in support of excellence in instruction in MPG courses. The goals of the workshop were to: a) develop an integrated, comprehensive and reviewed curriculum for MPG courses, and to seek ways to make connections with the larger geoscience curriculum; b) to explore emerging topics in MPG such as geobiology and climate change; c) demonstrate effective methods in teaching MPG in the context of Earth system science; d) share effective teaching activities and strategies for the classroom, laboratory and field including advances in pedagogy, assessments and research on learning; e) keep faculty current on recent advances in mineralogy, petrology and geochemistry research and to apply these findings to our teaching; f) explore and utilize current societal and global issues that intersect mineralogy, petrology and geochemistry to heighten the relevancy of course content for students; and h) meet colleagues and foster future teaching and research collaborations. A significant outcome of this workshop is a peer reviewed of collection of 300+ existing teaching activities, and a gap analysis to identify teaching activities needed to make these collections comprehensive and coherent. In addition, a series of thematic collections were developed to assist high priority

  13. Deep Seismic Reflectivity at Volcanic Margins: Reflections from the Petrological Moho or from within the Mantle?

    NASA Astrophysics Data System (ADS)

    Kusznir, Nick; Roberts, Alan; Bellingham, Paul

    2015-04-01

    Advances in deep long-offset seismic-reflection acquisition and processing now frequently provide imaging of strong and laterally continuous reflectors in the TWTT range of 10 to 14 seconds. While an initial interpretation might be that these reflectors correspond to the crust-mantle interface, this interpretation may in some cases be incorrect or over-simplistic. Do these deep reflectors correspond to the petrological Moho or could they be located within the mantle? Examples of deep laterally-coherent reflectivity can be seen within the ocean-continent transition of the Argentine, Uruguayan and S Brazilian volcanic margins of the S Atlantic. An initial qualitative interpretation of the seismic data suggests the presence of deep crustal "keels" or crustal roots underlying well developed seaward dipping reflectors (SDRs). Joint inversion of the PSTM time-domain seismic reflection and gravity anomaly data has been used to determine the average interval density and seismic velocity between base sediment and the deep seismic reflectivity. Joint inversion densities and seismic velocities for this depth interval reach values in excess of 3000 kg/m3 and 7.0 km/sec for the entire thickness of the interval, substantially in excess of densities and velocities observed for normal oceanic and continental crust. The high densities determined from joint seismic-gravity inversion under the SDR regions are also consistent with results from flexural subsidence analysis. We consider two interpretations of these results. One interpretation is that the strong deep reflectivity corresponds to the base of the petrological crust and that the crust has an abnormally high average density and seismic velocity due to high-temperature mantle-plume-related magmatism. An alternative interpretation is that the deep seismic reflectivity is located within the mantle beneath the petrological Moho, and that the high density and seismic velocity result from averaging of both crustal basement (~2850

  14. Are Deep Seismic Reflections at Volcanic Margins from the Petrological Moho or from within the Mantle?

    NASA Astrophysics Data System (ADS)

    Harkin, C. J.; Kusznir, N. J.; Roberts, A. M.; Bellingham, P.; Manatschal, G.

    2015-12-01

    Deep long-offset seismic-reflection now frequently provide imaging of strong and laterally continuous reflectors in the TWTT range of 10 to 14 seconds. Examples of deep laterally-coherent reflectivity can be seen within the ocean-continent transition of the Argentine, Uruguayan and S Brazilian volcanic margins of the S Atlantic. Qualitative interpretation of the seismic data suggests the presence of deep crustal "keels" or crustal roots underlying well developed seaward dipping reflectors (SDRs). While an initial interpretation might be that these reflectors correspond to the crust-mantle interface, this interpretation may in some cases be incorrect or over-simplistic. Do these deep reflectors correspond to the petrological Moho or could they be located within the mantle? Joint inversion of the PSTM time-domain seismic reflection and gravity anomaly data has been used to determine the average interval density and seismic velocity between base sediment and the deep seismic reflectivity. Joint inversion densities and seismic velocities for this depth interval reach values in excess of 3000 kg/m3 and 7.0 km/sec for the entire thickness of the interval, substantially in excess of densities and velocities observed for normal oceanic and continental crust. The high densities determined from joint seismic-gravity inversion under the SDR regions are also consistent with results from flexural subsidence analysis. We consider two interpretations of these results. One interpretation is that the strong deep reflectivity corresponds to the base of the petrological crust and that the crust has an abnormally high average density and seismic velocity due to high-temperature mantle-plume-related magmatism. An alternative interpretation is that the deep seismic reflectivity is located within the mantle beneath the petrological Moho, and that the high density and seismic velocity result from averaging of both crustal basement (~2850 kg/m3) and mantle (~3300 kg/m3) values. In some

  15. Composition and Petrology of HED Polymict Breccias: The Regolith of (4) Vesta

    NASA Technical Reports Server (NTRS)

    Mittlefehldt, David W.; Cartwright, J. A.; Herrin, J. S.; Mertzman, S. A.; Mertzman, K. R.; Peng, Z. X.; Quinn, J. E.

    2012-01-01

    The polymict breccias of the howardite, eucrite and diogenite (HED) clan of meteorites preserve records of regolith processes that occur on Vesta, their putative home world. These breccias -- howardites, polymict eucrites and polymict diogenites -- are impact-engendered mixtures of diogenites and eucrites. The compositions of polymict breccias can be used to constrain the lithologic diversity of the vestan crust and the excavation depths of these materials. We have done petrological and compositional studies of multiple samples of 5 polymict eucrites and 28 howardites to investigate these issues. Older analyses were done on samples of approx 0.5 gram mass by INAA; newer analyses on samples of approx 5 gram mass by XRF and ICP-MS. We estimate the percentage of eucritic material (POEM) of polymict breccias by comparing their Al and/or Ca contents to those of average basaltic eucrite and diogenite. Our samples have POEM ranging from 28 to 98; adding two polymict diogenites from extends the range to POEM 10. One hypothesis is that ancient, well-mixed vestan regolith has POEM approx 67 and has a higher content of admixed impactor material. Several of our howardites have POEM of 59-74 (Al and/or Ca contents +/- 10% of POEM 67); about a third have Ni contents >300 micro g/g suggesting they contain >2% chondritic material (CM and/or CR). These may be regolithic howardites. Only one (LEW 85313) contains Ne dominated by a solar wind (SW) component. PCA 02066 is dominated by impact-melt material of polymict parentage and petrologically appears to be a mature regolith breccia, yet it does not contain SW-Ne. GRO 95602 falls within the POEM window, contains SW-Ne], yet has a Ni content of 193 micro g/g. Its petrologic characteristics suggest it was formed from immature regolith (no polymict breccia clasts; no glass). Trace element characteristics of the polymict breccias demonstrate the dominance of main-group eucrites as the basaltic component. Mixing diagrams of Zr, Nb, Ba, Hf

  16. Hydrothermal alteration and tectonic setting of intrusive rocks from East Brawley, Imperial Valley: an application of petrology to geothermal reservoir analysis

    SciTech Connect

    Keskinen, M.; Sternfeld, J.

    1982-01-01

    A geothermal well near East Brawley intersected a series of thin (3 to 35m) diabasic to dioritic intrusives. The petrology and chemistry of these meta-igneous rocks can provide insight into the thermal and fluid chemical characteristics of the reservoir and into the processes of magma generation at depth. A description of the rock types and their hydrothermal alteration is presented in order to increase the petrologic data base relating to this important facet of the geothermal potential of the Salton Trough and to provide a case study illustrating how detailed petrologic examination of well cuttings can provide important input in the construction of a geothermal reservoir model.

  17. Assessing the link between mantle source and sub-volcanic plumbing in the petrology of basalts from the 2001 and 2002/2003 eruptions of Mount Etna, Sicily: Evidence from geochemical and helium isotope data

    NASA Astrophysics Data System (ADS)

    Coulson, Ian M.; Stuart, Finlay M.; MacLean, Natalie J.

    2011-04-01

    The 2001 and 2002-2003 flank eruptions of Mt. Etna consisted of near continuous explosive activity and sporadic lava flows. Previous studies have suggested that distinct magmas were simultaneously tapped by fissures in different parts of the volcano, indicating a complex plumbing system. From textural and chemical data it has been suggested that "eccentric" eruptions on the south flank were fed by a deep-seated reservoir that is not related to the central conduit. In contrast, materials erupted above 2600 m and from the northeast flank represent partially degassed, more fractionated magma, typical of that residing within the central vents. A concern is that Etna has entered a new phase of activity, with magma supply from a deep reservoir that is capable of generating recurrent flank eruptions posing significant hazard to populated areas and air travel. We have investigated materials that erupted from different vents during both the 2001 and 2002/3 eruptive episodes by means of petrology, whole-rock chemistry and helium isotopic methods. Here we show from trace element chemistry and the 3He/ 4He isotope record of melt inclusions in olivine that the mantle source for both magma batches is identical. Furthermore, this magmatic source has not changed over the past 0.5 Ma. As such, our data support the premise that the petrological variability exhibited by products that erupted from different parts of the volcano reflects storage, fractionation and degassing at different levels within the crust.

  18. Magnetic properties of low-petrologic grade non-carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Sugiura, N.; Strangway, D. W.

    1982-12-01

    Magnetic properties and paleointensities are reported for several low-petrologic-grade noncarbonaceous chondrites. Enstatite chondrites are far more magnetic than others and record ancient fields of 7-16 Oe. Abee has nearly random NRM in clasts and matrix samples, suggesting preaccretional remanence. Indarch and Yamato-691 record high fields, but have a single direction of magnetization, so that it cannot be determined whether the magnetic record is of pre- or postaccretional origin. Bjurbole, Chainpur, Mezo Madaras, and Yamato-74191 have random (and stable) NRM components carried by plessite, indicating possible preaccretional remanence. However, Bjurbole and Mezo Madaras are thought to have been reheated to above 500 C after their accretion, and in that case the random NRM in these chondrites could not be preaccretional.

  19. Thermal regimes in impact melts and the petrology of the Apollo 17 Station 6 boulder

    NASA Technical Reports Server (NTRS)

    Simonds, C. H.

    1975-01-01

    A progress report is presented on the petrologic study of the Station 6 boulder, taking into account the implications of its petrographic and geochemical studies to the understanding of the processes of formation and crystallization of impact melts. The interpretation of the data from the boulder suggests processes that appear reasonable for a petrogenetic model of impact events large enough to produce a layer of melt a kilometer or more wide and at most a few tens of meters thick. A summary of the model is presented. The primary difference between the new model and the previous models of Warner et al. (1973, 1974) and Simonds et al. (1973, 1974) is that melt and clasts are derived from distinctly different parts of the cratering regime. The cooling is modeled in two steps, first the rapid equilibration between clasts and matrix, and second, the much slower loss of heat to the surroundings.

  20. Global petrologic variations on the moon: a ternary-diagram approach.

    USGS Publications Warehouse

    Davis, P.A.; Spudis, P.D.

    1987-01-01

    A ternary-diagram approach for determination of global petrologic variations on the lunar surface is presented that incorporates valuable improvements in our previous method of using geochemical variation diagrams. Our results are as follows: 1) the highlands contain large areas of relatively pure ferroan anorthosite; 2) the average composition of the upper lunar crust is represented by an 'anorthositic gabbro' composition; 3) KREEP/Mg-suite rocks are a minor fraction of the upper lunar crust; 4) within the farside highlands, areas of KREEP/Mg-suite rocks coincide mostly with areas of crustal thinning; 5) portions of the E limb and farside highlands have considerable amounts of a mafic, chondritic Th/Ti component (like mare basalt) whose occurrences coincide with mapped concentrations of light plains that display dark-halo craters.- from Authors

  1. Magnetic petrology of eastern North America diabases. I - Olivine-normative dikes from western South Carolina

    NASA Technical Reports Server (NTRS)

    Warner, Richard D.; Wasilewski, Peter J.

    1990-01-01

    The oxide mineralogy and the magnetic behavior of 15 olivine-normative samples obtained from South-Caroline diabase dikes were investigated using electron microprobe and SEM analyses and measurements of natural remanence magnetization (NRM), saturation isothermal remanence magnetization (SIRM), and anhysteritic remanence magnetization. It was found that chromite (which for these olivine-normative diabases is a sensitive petrologic indicator) constitutes up to 0.5 vol pct and that its abundance and composition correlate with bulk rock Cr. Microscopic analyses showed that titanomagnetite compositions were mostly between 0.4 and 0.55. The values of NRM and the NRM/SIRM ratios varied between 4 and 0.01 A sq m/kg and 0.0019 and 0.032, respectively. These properties inversely correlate with Cr content and demonstrably contrast Cr-rich and Cr-poor samples.

  2. Petrology and geochemistry of lithic fragments separated from the Apollo 15 deep-drill core

    NASA Technical Reports Server (NTRS)

    Lindstrom, M. M.; Nielsen, R. L.; Drake, M. J.

    1977-01-01

    Petrological and geochemical analysis of lithic fragments separated from the Apollo 15 deep-drill core showed these fragments to fall into the essentially the same range of rock types as observed in surface soil samples and large rock samples. Three particles are singled out as being of special interest. One sample is a mare basalt containing extremely evolved phases. The particle may represent small-scale imperfect crystal/liquid separation in a lava flow. A green glass particle is not the ultramafic emerald green glass described from the Apollo 15 site, but rather an ANT-like light green color, and has a quite different chemical composition from the ultramafic variety. One mare basalt displays a positive Eu anomaly and is enriched in plagioclase relative to olivine plus pyroxene.

  3. Petrology of Amoeboid Olivine Aggregates in Antarctic CR Chondrites: Comparison With Other Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

    Komatsu, M.; Fagan, T. J.; Yamaguchi, A.; Mikouchi, T.; Zolensky, M. E.; Yasutake, M.

    2016-01-01

    Amoeboid olivine aggregates (AOAs) are important refractory components of carbonaceous chondrites and have been interpreted to represent solar nebular condensates that experienced high-temperature annealing, but largely escaped melting. In addition, because AOAs in primitive chondrites are composed of fine-grained minerals (forsterite, anorthite, spinel) that are easily modified during post crystallization alteration, the mineralogy of AOAs can be used as a sensitive indicator of metamorphic or alteration processes. AOAs in CR chondrites are particularly important because they show little evidence for secondary alteration. In addition, some CR AOAs contain Mn-enriched forsterite (aka low-iron, Mn-enriched or LIME olivine), which is an indicator of nebular formation conditions. Here we report preliminary results of the mineralogy and petrology of AOAs in Antarctic CR chondrites, and compare them to those in other carbonaceous chondrites.

  4. Petrology and thermal history of type IA chondrules in the Semarkona (LL3.0) chondrite

    NASA Technical Reports Server (NTRS)

    Jones, R. H.; Scott, E. R. D.

    1989-01-01

    Detailed petrologic studies have been made of 15 type IA, Fe-poor, porphyritic olivine chondrules in Semarkona (LL3.0). Major and minor element concentrations in olivines, pyroxenes, and mesostases, and bulk composition so the chondrules are measured along with zoning profiles in the olivine and pyroxene crystals. The mineral compositions and textures are best interpreted in terms of closed system crystallization in which the olivines and pyroxenes crystallized in situ from a melt corresponding to the bulk composition of the chondrule. Relict olivine grains are not found in the chondrules. Crystallization probably occurred at a cooling rate of the order of 1000 C/hr. Precursor materials of the chondrules were composed of two components, one refractory Ca-, Al-, and Ti-rich, and one less refractory Si-, Fe-, Cr-, and Mn-rich. The evidence is consistent with Semarkona being one of the least metamorphosed ordinary chondrites.

  5. Petrologic monitoring of 1981 and 1982 eruptive products from mount st. Helens.

    PubMed

    Cashman, K V; Taggart, J E

    1983-09-30

    New material from the dacite lava dome of Mount St. Helens, collected soon after the start of each successive extrusion, is subjected to rapid chemical and petrologic analysis. The crystallinity of the dacite lava produced in 1981 and 1982 is 38 to 42 percent, about 10 percent higher than for products of the explosive 1980 eruptions. This increase in crystallinity accompanies a decrease in the ratio of hornblende to hornblende plus orthopyroxene, which suggests that the volatile-rich, crystal-poor material explosively erupted in 1980 came from the top of a zoned magma chamber and that a lower, volatile-poor and crystal-rich region is now being tapped. The major-element chemistry of the dacite lava has remained essentially constant (62 to 63 percent silica) since August 1980, ending a trend of decreasing silica seen in the products of the explosive eruptions of May through August 1980.

  6. Characteristics of Moho transition zone: MCS reflection records and petrological aspects and physical properties

    NASA Astrophysics Data System (ADS)

    Kasahara, J.; Tsuruga, K.; Ike, T.; Unou, S.; Koda, K.

    2008-12-01

    The Moho is defined as the seismological discontinuity at the crust and mantle boundary. Its global depth, thickness of transition zone, and velocity structure has not been studied well. It is also poorly known whether the Moho has the same petrological and seismological properties in the continent and in the ocean, or not. Previous studies propose several petrological models for the Moho: 1) phase transition boundary from basalt to eclogite, and 2) material boundary of mafic and ultramafic rocks. By the petrological observation in the Oman ophiolite, the oceanic crust is modeled as 3) diabase-homogeneous gabbro - layered gabbro - Moho transition layer - harzburgite. The thickness of Moho transition zone (MTZ), at the boundary between Earth's crust and the subjacent mantle, has significant effect on the seismic responses from the Moho. We examined seismic characteristics of Moho reflection (hereafter PmP) using MCS (Multi Channel Seismic) reflection records obtained by high quality seismic experiments in the western Pacific by JOGMEC (Japan Oil, Gas and MEtals national Corporation). The MCS records show clear reflections at ~ 6-10 km in depth from the ocean bottom in the north and south of Ogasawara Plateau. However, considering horizontal variation in the PmP intensity, the nature of the MTZ varies from place to place. In the seismic profile D00-D, across Ogasawara Plateau in the N-S direction, the PmP abruptly disappears far from the nearby seamount where the overlain sedimentary section has less change. In another case, shown in D00-C that is located 130km west of D00-D, the PmP clearly shows high-amplitude continuous reflection near the seamount's flank. Data acquisition is relatively constant for the Ogasawara MCS reflection lines; therefore, the difference in the PmP intensity between D00- D and D00-C may relate to the nature of the Moho. The comparison of reflection records and synthetic waveforms calculated by Tsuruga et al.(this meeting) shows that if the

  7. Petrologic monitoring of 1981 and 1982 eruptive products from Mount St. Helens

    USGS Publications Warehouse

    Cashman, K.V.; Taggart, J.E.

    1983-01-01

    New material from the dacite lava dome of Mount St. Helens, collected soon after the start of each successive extrusion, is subjected to rapid chemical and petrologic analysis. The crystallinity of the dacite lava produced in 1981 and 1982 is 38 to 42 percent, about 10 percent higher than for products of the explosive 1980 eruptions. This increase in crystallinity accompanies a decrease in the ratio of hornblende to hornblende plus orthopyroxene, which suggests that the volatile-rich, crystal-poor material explosively erupted in 1980 came from the top of a zoned magma chamber and that a lower, volatile-poor and crystal-rich region is now being tapped. The major-element chemistry of the dacite lava has remained essentially constant (62 to 63 percent silica) since August 1980, ending a trend of decreasing silica seen in the products of the explosive eruptions of May through August 1980.

  8. Planet Alsioff - A problem set for students of phase equilibria or metamorphic petrology

    NASA Technical Reports Server (NTRS)

    Burt, Donald M.

    1988-01-01

    This paper presents a problem set that contains questions for students of phase equilibria or metamorphic petrology concerning a hypothetical planet Alsioff, for which incomplete data are given. On this panet, the SiF4 is the major volatile and Al, Si, O, and F are the only elements present. Progressive metamorphism on Alsioff mainly involves devolatilization of fluid SiF4. The problem set includes ten questions. Some of these are concerned with possible chemical reactions that should affect water, wollastonite, or Ca-SiO3 exposed to the atmosphere of Alsioff; the mechanism of controls of the O2 and F2 contents of the Alsioffian atmosphere; and the devolatilization reactions involving SiF4 with progressive thermal metamorphism.

  9. Palaeomagnetism, petrology and geochronology of tertiary magmatic and sedimentary units from Iran

    NASA Astrophysics Data System (ADS)

    Bina, Mohamad Mansour; Bucur, Ileana; Prevot, Michel; Meyerfeld, Yves; Daly, Lucien; Cantagrel, Jean Marie; Mergoil, Jean

    1986-01-01

    An amount of 160 samples from igneous and sedimentary formations of Palaeocene or Eocene age was collected in Iran, northeast of the Zagros belt. Palaeomagnetic analyses, petrological studies, and K-Ar dating indicate Palaeocene and Eocene palaeomagnetic directions in the Zabol-Baluch region (East Iranian Range) and show that the area remained approximately stable with respect to the Eurasian and African plates from the beginning of the Cainozoic Era. Conversely, large post-Eocene deformations occurred in Central Iran. These large rotations are both clockwise and anti-clockwise. They might have resulted from lateral shears between Arabia and northeast Iran. The Central Elburz underwent a large clockwise rotation which is probably late Oligocene in age. As a whole, our results show that the so-called "Persian Plate" did not exist during the Cainozoic Era.

  10. Potential contributions of metamorphic petrology studies in an ultra-deep drillhole in the southern Appalachians

    SciTech Connect

    Speer, J.A.

    1985-01-01

    The proposed, ultra-deep hole in the southeast U.S. will penetrate allochthonous, medium- to high-grade metamorphic rocks of the Inner Piedmont and Blue Ridge thrust sheets. It is anticipated that the hole will then encounter autochthonous low-grade, metasedimentary cover rocks before bottoming out in crystalline Precambrian basement rocks. Metamorphic petrology in the recent past has concentrated on unraveling the physical and chemical history (P, T, X/sub fluid/, etc.) of metamorphic rocks. The techniques that have been developed are ideally suited to the study of relatively limited samples from drill core. Detailed studies of the allochthonous and autochthonous rocks from the drillhole, combined with comparable studies of the surface rocks, by metamorphic petrologists experimented with these approaches, would give a 3-dimensional picture of the PTX evolution in the region of the ultra-deep hole, and thus an idea of the geometrical, chemical, and physical changes the rocks experienced. This would place constraints on conditions of the rocks before and after thrusting and thus any tectonic models of thrusting in the southern Appalachians. With limited sampling this could be a problem, with more complete sampling it will be an advantage. The metamorphic petrology of the rocks will provide basic support for the other studies of the drill core and drillhole, most notably geochronology and stable isotopes. It should not be forgotten that in addition to the historical metamorphism, the expected, present-day conditions in the drillhole are those of burial metamorphism. The hole will present an excellent opportunity to study such active metamorphic conditions.

  11. Basaltic Magmatism: The Dominant Factor in the Petrologic and Tectonic Evolution of the Earth

    NASA Technical Reports Server (NTRS)

    Lowman, Paul D., Jr.

    2003-01-01

    Silicate bodies such as the Moon, Mars, probably Mercury, and possibly Venus, appear to have evolved in three main stages: a first (felsic) differentiation, a late heavy bombardment, and a second (basaltic) differentiation. It has been proposed that the Earth underwent a similar sequence. This paper argues that the second differentiation, basaltic magmatism, has dominated the petrologic and tectonic evolution of the Earth for four billion years. A global andesitic crust, formed during and after accretion of the planet, was disrupted by major impacts that triggered mantle upwelling and sea-floor spreading about 4 billion years ago. The oceanic crust collectively has since been formed by basaltic volcanism, from spreading centers and mantle plumes. However, the continental crust has also been greatly affected. Basaltic underplating has promoted anatexis and diapiric intrusion of granitoids in granite-greenstone terrains, as well as providing heat for regional metamorphism. Basaltic intrusions, such as the Nipissing diabase of the Sudbury area, have added to the thickness of continental crust. Satellite magnetic surveys suggest that there are more such basaltic intrusions than previously realized; examples include the Bangui anomaly of central Africa and the Kentucky anomaly. Basaltic overplating from mafic dike swarms has repeatedly flooded continents; had it not been for erosion, they would be covered with basalt as Venus is today. The tectonic effects of basaltic volcanism on continents have only recently been realized. The World Stress Map project has discovered that continents are under horizontal compressive stress, caused by push from mid-ocean ridges, i.e., by basaltic volcanism. The stress fields are generally uniform over large intraplate areas, and could contribute to intraplate tectonism. Seafloor spreading has demonstrably been effective for at least 200 million years, and ridge push thus a contributor to tectonic activity for that long. Collectively, the

  12. Magma storage conditions beneath Dabbahu Volcano (Ethiopia) constrained by petrology, seismicity and satellite geodesy

    NASA Astrophysics Data System (ADS)

    Field, L.; Blundy, J.; Brooker, R. A.; Wright, T.; Yirgu, G.

    2012-07-01

    A variety of methods exist to constrain sub-volcanic storage conditions of magmas. Petrological, seismological and satellite geodetic methods are integrated to determine storage conditions of peralkaline magmas beneath Dabbahu Volcano, Afar, Ethiopia. Secondary ion mass spectrometry (SIMS) analysis of volatile contents in melt inclusions trapped within phenocrysts of alkali feldspar, clinopyroxene and olivine from pantellerite obsidians representing the youngest eruptive phase (<8 ka) show H2O contents ≤5.8 wt.% and CO2 contents generally below 500 ppm, although rarely as high as 1,500 ppm. Volatile saturation pressures (at 679-835°C) are in the range 43-207 MPa, consistent with published experimental data for similar pantellerites, which show that the phenocryst assemblage of alkali feldspar + cpx + aenigmatite ± ilmenite is stable at 100 to 150 MPa. Inferred magma storage depths for these historic eruptions are ~1-5 km below sea-level, consistent with the depths of earthquakes, associated with magma chamber deflation following a dyke intrusion in the period Oct 2005-Apr 2006. Interferometric synthetic aperture radar (InSAR) data for the same period reveal a broad ~20 km diameter area of uplift. Modelling of different geometries reveals that a series of stacked sills over a 1-5 km depth range best matches the InSAR data. The consistency of depth estimates based on petrological study of ancient eruptions and the seismicity, inflation and deflation of Dabbahu observed in relation to the dyking event of 2005, suggest a small but vertically extensive and potentially long-lived magma storage region.

  13. The Distant Morphological and Petrological Features of Shock Melt Veins in the Suizhou L6 Condrite

    SciTech Connect

    X Xie; Z Sun; M Chen

    2011-12-31

    The morphology and petrology of distinct melt veins in the Suizhou L6 chondrite have been investigated using scanning electron microscopy, electron microprobe analyses, and Raman spectroscopy, synchrotron energy-dispersive diffraction, and transmission electron microscopy. It is found that the melt veins in the Suizhou meteorite morphologically are the simplest, straightest, and thinnest among all shock veins known from meteorites. At first glance, these veins look like fine fractures, but petrologically they are solid melt veins of chondritic composition and consist of fully crystalline materials of two distinct lithological assemblages, with no glassy material remaining. The Suizhou melt veins contain the most abundant high-pressure mineral species when compared with all other veins known in chondrites. Thus, these veins in Suizhou are classified as shock veins. All rock-forming and almost all accessory minerals in the Suizhou shock veins have been transformed to their high-pressure polymorphs, and no fragments of the precursor minerals remain in the veins. Among the 11 high-pressure mineral phases identified in the Suizhou veins, three are new high-pressure minerals, namely, tuite after whitlockite, xieite, and the CF phase after chromite. On the basis of transformation of plagioclase into maskelynite, it is estimated that the Suizhou meteorite experienced shock pressures and shock temperatures up to 22 GPa and 1000 C, respectively. Shearing and friction along shock veins raised the temperature up to 1900-2000 C and the pressure up to 24 GPa within the veins. Hence, phase transition and crystallization of high-pressure minerals took place only in the Suizhou shock veins. Fast cooling of the extremely thin shock veins is regarded as the main reason that up to 11 shock-induced high-pressure mineral phases could be preserved in these veins.

  14. Petrologic considerations for hot dry rock geothermal site selection in the Clear Lake Region, California

    SciTech Connect

    Stimac, J.; Goff, F. ); Hearn, B.C. Jr. )

    1992-01-01

    The Clear Lake area is well known for anomalous heat flow, thermal springs, hydrothermal mineral deposits, and Quaternary volcanism. These factors, along with the apparent lack of a large reservoir of geothermal fluid north of Collayomi fault make the Clear Lake area an attractive target for hot dry rock (HDR) geothermal development. Petrologic considerations provide some constraints on site selection for HDR development. Spatial and temporal trends in volcanism in the Coast Ranges indicate that magmatism has migrated to the north with time, paralleling passage of the Mendocino triple junction and propagation of the San Andreas fault. Volcanism in the region may have resulted from upwelling of hot asthenosphere along the southern margin of the subducted segment of the Gorda plate. Spatial and temporal trends of volcanism within the Clear Lake volcanic field are similar to larger-scale trends of Neogene volcanism in the Cost Ranges. Volcanism (especially for silicic compositions) shows a general migration to the north over the {approximately}2 Ma history of the field, with the youngest two silicic centers located at Mt. Konocti and Borax Lake. The Mt. Konocti system (active from {approximately} 0.6 to 0.3 Ma) was large and long-lived, whereas the Borax Lake system is much smaller but younger (0.09 Ma). Remnants of silicic magma bodies under Mt. Konocti may be in the latter stages of cooling, whereas a magma body centered under Borax Lake may be in the early stages of development. The existence of an upper crustal silicic magma body of under Borax Lake has yet to be demonstrated by passive geophysics, however, subsurface temperatures in the area as high (> 200{degrees}C at 2000 m) as those beneath the Mt. Konocti area. Based on petrologic considerations alone, the Mt. Konocti-Borax Lake area appears to be the most logical choice for HDR geothermal development in the region.

  15. Lateral variation in geochemistry, petrology, and palynology in the Elswick coal bed, Pike County, Kentucky

    USGS Publications Warehouse

    Hower, J.C.; Ruppert, L.F.; Eble, C.F.

    2007-01-01

    The Middle Pennsylvanian/Langsettian (Westphalian A) Elswick coal bed, correlative to the Upper Banner of Virginia, is a rare example of a mined high-sulfur (> 2%) coal in Eastern Kentucky, a region known for low-sulfur coals. To characterize lateral variation in the geochemistry, petrography, and palynology of the Elswick coal bed, three sites were sampled along a southeast-northwest transect within a single mine. At the southeastern site, the lower 101??cm of the 116-cm thick coal is dull, generally dominated by durain and dull clarain. While all benches at this site fit within the previously-defined "mixed palynoflora - moderate/low vitrinite group," suggesting a stressed environment of deposition, the palynology of the benches of the dull interval show greater diversity than might be expected just from the petrology. Lithology is generally similar between the sites, but each site has some differences in the petrology. Overall, the coal bed shows significant lateral variation in properties at the mine scale, some of which can be attributed to the gain or loss of upper and lower lithologies, either through an actual physical merging or through the change in character of lithotypes. Sulfur content varies between the three sites examined for this study. Site 3, located in the northwestern portion of the study area is characterized by a strikingly high sulfur zone (7.45%) in the middle of the coal bed, a feature missing at the other sites. Pyrite and marcasite, in a mid-seam lithotype at the northwestern site (site 3), show signs of overgrowths, indicating multiple generations of sulfide emplacement. The high-sulfur site 3 lithologies all have massive overgrowths of euhedral and framboidal pyrite, fracture- and cleat-fill pyrite, and sulfide emplacement in fusinite lumens. Sulfur is high throughout the mine area, but variations are evident in the extent of secondary growth of sulfides. ?? 2006 Elsevier B.V. All rights reserved.

  16. Isotopic and Elemental Compositions of Ar, Kr, and Xe in Bulk, Slow, and Fast Solar Wind Targets from Genesis

    NASA Astrophysics Data System (ADS)

    Vogel, N.; Baur, H.; Burnett, D. S.; Heber, V. S.; Wieler, R.

    2010-03-01

    We present new heavy noble gas isotopic and elemental data from GENESIS targets exposed to the bulk, the fast, and the slow solar wind. Implications on fractionation effects between the Sun and the Solar Wind will be discussed.

  17. Solar Wind Fractionation — Isotopic and Elemental — and Implications for Solar Compositions and Future Genesis Analyses

    NASA Astrophysics Data System (ADS)

    Wiens, R. C.; Reisenfeld, D. B.; Heber, V. S.; Burnett, D. S.

    2010-03-01

    Fractionation between solar wind and the solar photosphere is substantial, both for elements and isotopes. GENESIS measurements are key to understanding these fractionations, which will in turn provide more accurate solar compositions.

  18. Cleaning Genesis Mission Payload for Flight with Ultra-Pure Water and Assembly in ISO Class 4 Environment

    NASA Technical Reports Server (NTRS)

    Allton, Judith H.

    2012-01-01

    Genesis mission to capture and return to Earth solar wind samples had very stringent contamination control requirements in order to distinguish the solar atoms from terrestrial ones. Genesis mission goals were to measure solar composition for most of the periodic table, so great care was taken to avoid particulate contamination. Since the number 1 and 2 science goals were to determine the oxygen and nitrogen isotopic composition, organic contamination was minimized by tightly controlling offgassing. The total amount of solar material captured in two years is about 400 micrograms spread across one sq m. The contamination limit requirement for each of C, N, and O was <1015 atoms/sq cm. For carbon, this is equivalent to 10 ng/cm2. Extreme vigilance was used in pre-paring Genesis collectors and cleaning hardware for flight. Surface contamination on polished silicon wafers, measured in Genesis laboratory is approximately 10 ng/sq cm.

  19. Genesis of highland basalt breccias - A view from 66095

    NASA Technical Reports Server (NTRS)

    Garrison, J. R., Jr.; Taylor, L. A.

    1980-01-01

    Electron microprobe and defocused beam analyses of the lunar highland breccia sample 66095 show it consists of a fine-grained subophitic matrix containing a variety of mineral and lithic clasts, such as intergranular and cataclastic ANT, shocked and unshocked plagioclase, and basalts. Consideration of the chemistries of both matrix and clasts provides a basis for a qualitative three-component mixing model consisting of an ANT plutonic complex, a Fra Mauro basalt, and minor meteoric material.

  20. Genesis, types and evolution of crevice-type caves in the flysch belt of the Western Carpathians (Czech Republic)

    NASA Astrophysics Data System (ADS)

    Lenart, Jan; Pánek, Tomáš; Dušek, Radek

    2014-01-01

    Crevice-type caves are among the least investigated natural phenomena connected with the development of slope failures. These caves present complex and peculiar underground systems with their own development and resulting landforms. We investigated eight caves in the Czech part of the Outer Western Carpathians to determine their genesis, types and evolution. Crevice formation is predisposed according to the lithological, tectonic and morphological characteristics of the landslide body, including the position and location of bedding planes, joints and faults. We performed several analyses, including speleological mapping, evaluation of high-resolution topography above the caves, geophysical (ERT) measurements and structural investigations within cave passages. In accordance with these analyses, various mechanisms responsible for cave development were revealed. An intra-bed translation is responsible for the creation of regularly shaped passages with flat ceilings. Toppling as well as back and horizontal rotation of rock blocks determine the specific morphology and shapes of passages. A relatively novel aspect of the current study is the identification of the subsidence of massive rock wedges due to the widening of cracks. All of these mechanisms control the specific morphological characteristics within crevices, e.g., typical shapes of passages, cave level ordering and ceiling types. Some of these processes also influence topography above the caves. Finally, the different phases of evolution of these caves were determined.

  1. Modeling Ellipsometry Measurements of Molecular Thin-Film Contamination on Genesis Array Samples

    NASA Technical Reports Server (NTRS)

    Calaway, Michael J.; Stansbery, E. K.; McNamara, K. M.

    2006-01-01

    The discovery of a molecular thin-film contamination on Genesis flown array samples changed the course of preliminary assessment strategies. Analytical techniques developed to measure solar wind elemental abundances must now compensate for a thin-film contamination. Currently, this is done either by experimental cleaning before analyses or by depth-profiling techniques that bypass the surface contamination. Inside Johnson Space Center s Genesis dedicated ISO Class 4 (Class 10) cleanroom laboratory, the selection of collector array fragments allocated for solar wind analyses are based on the documentation of overall surface quality, visible surface particle contamination greater than 1 m, and the amount of thin film contamination measured by spectroscopic ellipsometry. Documenting the exact thickness, surface topography, and chemical composition of these contaminates is also critical for developing accurate cleaning methods. However, the first step in characterization of the molecular film is to develop accurate ellipsometry models that will determine an accurate thickness measurement of the contamination film.

  2. GENESI-DR: Discovery, Access and on-Demand Processing in Federated Repositories

    NASA Astrophysics Data System (ADS)

    Cossu, Roberto; Pacini, Fabrizio; Parrini, Andrea; Santi, Eliana Li; Fusco, Luigi

    2010-05-01

    GENESI-DR (Ground European Network for Earth Science Interoperations - Digital Repositories) is a European Commission (EC)-funded project, kicked-off early 2008 lead by ESA; partners include Space Agencies (DLR, ASI, CNES), both space and no-space data providers such as ENEA (I), Infoterra (UK), K-SAT (N), NILU (N), JRC (EU) and industry as Elsag Datamat (I), CS (F) and TERRADUE (I). GENESI-DR intends to meet the challenge of facilitating "time to science" from different Earth Science disciplines in discovery, access and use (combining, integrating, processing, …) of historical and recent Earth-related data from space, airborne and in-situ sensors, which are archived in large distributed repositories. In fact, a common dedicated infrastructure such as the GENESI-DR one permits the Earth Science communities to derive objective information and to share knowledge in all environmental sensitive domains over a continuum of time and a variety of geographical scales so addressing urgent challenges such as Global Change. GENESI-DR federates data, information and knowledge for the management of our fragile planet in line with one of the major goals of the many international environmental programmes such as GMES, GEO/GEOSS. As of today, 12 different Digital Repositories hosting more than 60 heterogeneous dataset series are federated in GENESI-DR. Series include satellite data, in situ data, images acquired by airborne sensors, digital elevation models and model outputs. ESA has started providing access to: Category-1 data systematically available on Internet; level 3 data (e.g., GlobCover map, MERIS Global Vegetation Index); ASAR products available in ESA Virtual Archive and related to the Supersites initiatives. In all cases, existing data policies and security constraints are fully respected. GENESI-DR also gives access to Grid and Cloud computing resources allowing authorized users to run a number of different processing services on the available data. The GENESI

  3. Using Image Pro Plus Software to Develop Particle Mapping on Genesis Solar Wind Collector Surfaces

    NASA Technical Reports Server (NTRS)

    Rodriquez, Melissa C.; Allton, J. H.; Burkett, P. J.

    2012-01-01

    The continued success of the Genesis mission science team in analyzing solar wind collector array samples is partially based on close collaboration of the JSC curation team with science team members who develop cleaning techniques and those who assess elemental cleanliness at the levels of detection. The goal of this collaboration is to develop a reservoir of solar wind collectors of known cleanliness to be available to investigators. The heart and driving force behind this effort is Genesis mission PI Don Burnett. While JSC contributes characterization, safe clean storage, and benign collector cleaning with ultrapure water (UPW) and UV ozone, Burnett has coordinated more exotic and rigorous cleaning which is contributed by science team members. He also coordinates cleanliness assessment requiring expertise and instruments not available in curation, such as XPS, TRXRF [1,2] and synchrotron TRXRF. JSC participates by optically documenting the particle distributions as cleaning steps progress. Thus, optical document supplements SEM imaging and analysis, and elemental assessment by TRXRF.

  4. North-south variations of tropical storm genesis locations in the Western Hemisphere

    NASA Astrophysics Data System (ADS)

    Wang, Chunzai; Wang, Lei; Wang, Xin; Wang, Dongxiao; Wu, Lixin

    2016-11-01

    In the Western Hemisphere, tropical storms or hurricanes form in the North Atlantic and eastern North Pacific. Previous studies have focused on storm variability in the frequency, duration, and intensity in each basin. Here we find that the tropical storm genesis location in one ocean basin ties to the other one. On both interannual and multidecadal time scales, a northward (southward) shift of the tropical storm genesis location is associated with a southward (northward) variation in the other ocean basin. The change of cross-Central America wind in the upper troposphere, which induces an out-of-phase relation of vertical wind shear, bridges storm activity in the two ocean basins. Sea surface temperatures in both the tropical Pacific and North Atlantic can induce the zonal wind change across Central America. An implication of this study is that hurricane outlooks can be improved by considering the two ocean basins together, and thus helping reduce the damage caused by hurricane landfall.

  5. Oxygen Isotope Analysis of a Genesis Solar Wind Concentrator Sample With MegaSIMS

    NASA Astrophysics Data System (ADS)

    Kallio, A. P.; McKeegan, K. D.; Mao, P. H.; Jarzebinski, G.; Coath, C. D.; Kunihiro, T.; Wiens, R. C.; Allton, J.; Callaway, M.; Rodriguez, M.; Burnett, D.

    2008-05-01

    The determination of the oxygen isotopic composition of the sun is the highest priority science objective of the GENESIS mission. We have performed the first oxygen isotopic analyses of the GENESIS solar wind concentrator sample #60001 using the UCLA MegaSIMS instrument. The MegaSIMS is a hybrid secondary ionisation and accelerator multicollector mass spectrometer. The problems of instrumental background, sample surface contamination (both adsorbed and particulate) and detector cross-talk can now be dealt with and we can measure consistently solar wind oxygen depth profiles. Our preliminary oxygen isotope data indicate that the solar wind sample is 16O enriched compared to terrestrial but the details of isotopic fractionation in the concentrator and in the solar wind itself have to be worked out before a value for the sun can be calculated.

  6. Preliminary Quantification of Image Color Gradient on Genesis Concentrator Silicon Carbine Target 60001

    NASA Technical Reports Server (NTRS)

    Allton, J. H.; Calaway, M. J.; Rodriquez, M. C.

    2008-01-01

    The Genesis spacecraft concentrator was a device to focus solar wind ions onto a 6-cm diameter target area, thus concentrating the solar wind by 20X [1]. The target area was comprised of 4 quadrants held in place by a gold-coated stainless steel "cross" (Fig. 1). To date, two SiC and one chemical vapor deposited (CVD) quadrants have been imaged at 5X using a Leica DM-6000M in autoscan mode. Complete imaging of SiC sample 60001 required 1036 images. The mosaic of images is shown in Fig. 2 and position of analyzed areas in Fig. 3. This mosaic imaging is part of the curatorial documentation of surface condition and mapping of contamination. Higher magnification (50X) images of selected areas of the target and individual contaminant particles are compiled into reports which may be requested from the Genesis Curator [2].

  7. Cleaning Surface Particle Contamination with Ultrapure Water (UPW) Megasonic Flow on Genesis Array Collectors

    NASA Technical Reports Server (NTRS)

    Allton, J. H.; Calaway, Michael J.; Hittle, J. D.; Rodriquez, M. C.; Stansbery, E. K.; McNamara, K. M.

    2006-01-01

    The hard landing experienced by the Genesis sample return capsule breached the science canister containing the solar wind collectors. This impact into the damp lakebed contaminated collector surfaces with pulverized collector and spacecraft materials and Utah sediment and brine residue. The gold foil, polished aluminum, and bulk metallic glass remained intact, but the solar wind bulk and regime-specific array collectors were jarred loose from their frames and fractured into greater than 10,000 specimens. After a year of investigation and cleaning experimentation, the Genesis Science Team determined that array collectors had 4 classes of contaminants: particles, molecular film, submicron inorganic particulate ("aerosol"), and pre-launch surface contamination. We discuss here use of megasonically energized ultrapure water (UPW) for removing particulate debris from array collector fragments.

  8. Polar Low genesis over the North Pacific under different global warming scenarios

    NASA Astrophysics Data System (ADS)

    Chen, Fei; von Storch, Hans; Zeng, Lili; Du, Yan

    2014-12-01

    Following an earlier climatological study of North Pacific Polar Lows by employing dynamical downscaling of NCEP1 reanalysis in the regional climate model COSMO-CLM, the characteristics of Polar Low genesis over the North Pacific under different global warming scenarios are investigated. Simulations based on three scenarios from the Special Report on Emissions Scenarios were conducted using a global climate model (ECHAM5) and used to examine systematic changes in the occurrence of Polar Lows over the twenty first century. The results show that with more greenhouse gas emissions, global air temperature would rise, and the frequency of Polar Lows would decrease. With sea ice melting, the distribution of Polar Low genesis shows a northward shift. In the scenarios with stronger warming there is a larger reduction in the number of Polar Lows.

  9. Observed warming trend in sea surface temperature at tropical cyclone genesis

    NASA Astrophysics Data System (ADS)

    Defforge, Cécile L.; Merlis, Timothy M.

    2017-01-01

    Tropical cyclone (TC) activity is influenced by environmental factors, and it is expected to respond to anthropogenic climate change. However, there is observational uncertainty in historical changes in TC activity, and attributing observed TC changes to anthropogenic forcing is challenging in the presence of internal climate variability. The sea surface temperature (SST) is a well-observed environmental factor that affects TC intensity and rainfall. Here we show that the SST at the time of TC genesis has a significant warming trend over the three decades of the satellite era. Though TCs are extreme events, the warming trend at TC genesis is comparable to the trend in SST during other tropical deep convection events and the trend in SST in the TC main development regions throughout the TC season. This newly documented, observed signature of climate change on TC activity is also present in high-resolution global atmospheric model simulations that explicitly simulate TCs.

  10. Genesis of a zoned granite stock, Seward Peninsula, Alaska

    USGS Publications Warehouse

    Hudson, Travis

    1977-01-01

    A composite epizonal stock of biotite granite has intruded a diverse assemblage of metamorphic rocks in the Serpentine Hot Springs area of north-central Seward Peninsula, Alaska. The metamorphic rocks include amphibolite-facies orthogneiss and paragneiss, greenschist-facies fine-grained siliceous and graphitic metasediments, and a variety of carbonate rocks. Lithologic units within the metamorphic terrane trend generally north-northeast and dip moderately toward the southeast. Thrust faults locally juxtapose lithologic units in the metamorphic assemblage, and normal faults displace both the metamorphic rocks and some parts of the granite stock. The gneisses and graphitic metasediments are believed to be late Precambrian in age, but the carbonate rocks are in part Paleozoic. Dating by the potassium-argon method indicates that the granite stock is Late Cretaceous. The stock has sharp discordant contacts, beyond which is a well-developed thermal aureole with rocks of hornblende hornfels facies. The average mode of the granite is 29 percent plagioclase, 31 percent quartz, 36 percent K-feldspar, and 4 percent biotite. Accessory minerals include apatite, magnetite, sphene, allanite, and zircon. Late-stage or deuteric minerals include muscovite, fluorite, tourmaline, quartz, and albite. The stock is a zoned complex containing rocks with several textural facies that are present in four partly concentric zones. Zone 1 is a discontinuous border unit, containing fine- to coarse-grained biotite granite, that grades inward into zone 2. Zone 2 consists of porphyritic biotite granite with oriented phenocrysts of pinkish-gray microcline in a coarse-grained equigranular groundmass of plagioclase, quartz, and biotite. It is in sharp, concordant to discordant contact with rocks of zone 3. Zone 3 consists of seriate-textured biotite granite that has been intruded by bodies of porphyritic biotite granite containing phenocrysts of plagioclase, K-feldspar, quartz, and biotite in an

  11. Petrology and geochemistry of Mesozoic granitic rocks from the Nansha micro-block, the South China Sea: Constraints on the basement nature

    NASA Astrophysics Data System (ADS)

    Yan, Quanshu; Shi, Xuefa; Liu, Jihua; Wang, Kunshan; Bu, Wenrui

    2010-01-01

    There are several micro-blocks dispersed in the South China Sea (SCS), e.g., Xisha-Zhongsha block, Nansha block and Reed-Northeastern Palawan block, etc., but detailed petrological constraints on their basement nature were previously lacking. The magmatic ages for granitic rock samples from two dredge stations in the Nansha micro-block vary from 159 to 127 Ma, which are comparable to magmatic activities occurred in the northern margin (Pearl river mouth), HongKong and East China. Petrographic characteristics, major-, trace element and Sr-Nd isotopic data of nine samples from two dredged station performed in the Nansha micro-block, the SCS, are reported. Petrographically, these granitic rocks can be divided into two groups which underwent a complex history of magmatic process, i.e., tonalitic rock (Group I) and monzogranitic rock (Group II). The Rittmann index ( σ) for these rocks (1.9-3.1) suggest that they belong to calc-alkaline rocks. Group I rocks which is of typical I-type, have higher contents of TiO 2, Al 2O 3, FeO, MgO, CaO, Na 2O and P 2O 5, but lower values of SiO 2 and K 2O, when compared with those of Group II with I-type characteristics. Group I rocks are produced by partial melting of older Precambrian basement with the variable influence of mantle-derived magma which results from the interaction of released fluids from the subducted slab and the overlying mantle wedge in a general convergent margin setting, and Group II rocks result from partial melting of lower crustal basic rocks (amphibolite) and/or further partial melting of the Group I rocks associated with the variable influence from the underplating mantle-derived magma resulting from lithospheric extensional regime. Both Groups I and II have undergone assimilation and fractional crystallization (AFC) processes during its petrogenesis. This study therefore demonstrates that there exists a continental basement within micro-blocks in the South China Sea, and further supports the idea that a

  12. WRF Simulation of the Genesis of Hurricane Javier (2004) in the Eastern Pacific

    NASA Technical Reports Server (NTRS)

    Braun, Scott A.

    2005-01-01

    The Eastern Pacific has the highest frequency of genesis events per unit area of any region worldwide (Elsberry et al 1987). African easterly waves, mesoscale convective systems (MCSs), and topographic effects are thought to play roles in the genesis of tropical cyclones there (Frank and Clark 1980, Velasco and Fritsch 1987, Zehnder 1991, Zehnder and Gall 1991; Farfan and Zehnder 1997). Mozer and Zehnder (1996), using dry, idealized simulations of flow past a large-scale three-dimensional mountain range comparable to the Sierra Madre Mountains of Mexico, showed that upstream flow blocking led to diversion of the flow primarily to the south of the mountains. This flow diversion led to the formation of a low-level, barotropically unstable jet (at a location comparable to the Isthmus of Tehuantepec) and the continuous formation of synoptic-scale vorticity maxima, which they suggested may play a role in tropical cyclogenesis. Farfan and Zehnder (1 997) examined the synoptic-scale circulations that led to the formation of Hurricane Guillermo (1991). Using numerical simulations, they found that flow blocking led to the formation of a low-level easterly jet south of the mountains of Central America and a northeasterly (gap flow) jet over the Gulf of Tehuantepec, which combined with the flow associated with the Intertropical Convergence Zone (ITCZ) to produce a closed cyclonic circulation in the location of Guillermo s formation. As will be discussed in this paper, the evolution of the flow field that was associated with the genesis of Hurricane Javier was similar to that described in Farfan and Zehnder (1997), with well-defined topographic flow features. Here, using a high- resolution simulation with the WRF model, we investigate whether these topographically induced flows played a significant role in the genesis of Javier.

  13. Exodus: redirecting Genesis for solar wind observations 4-8 million km from Earth

    NASA Astrophysics Data System (ADS)

    Steinberg, J.; Barraclough, B.; Gosling, J.; Reisenfeld, D.; Wiens, R.; Liewer, P.; Murphy, N.

    2003-04-01

    Genesis is an ongoing NASA Discovery mission designed to collect samples of the solar wind at L1 and return them to Earth for analysis. After the return capsule is dropped off in September, 2004, the spacecraft, with its in situ solar wind ion and electron spectrometers, is available to perform a new solar wind mission. Spacecraft capabilities, including ample remaining Dv, allow it to achieve and maintain a distant retrograde orbit, a heliocentric orbit in which the spacecraft spends a significant amount of time ˜0.025 AU upstream and downstream of Earth (˜2.5x the Earth-L1 distance). From this orbit Genesis observations may be used, together with those from available L1 spacecraft, to compare solar wind parameters across important spatial scales. The multi-point collaborative studies will uniquely allow us to understand the propagation and evolution of solar wind plasma, as well as the internal spatial structure of large solar wind transients, for spacecraft separation distances of 0.025 to 0.05 AU. Such separation distances are significantly greater than can be attained between any pair of current and proposed satellites in Earth or in L1 halo orbits. At the same time the separations will be small enough to allow confident tracking of particular solar wind structures between spacecraft. In addition to groundbreaking science, the Genesis spacecraft would be a pathfinder for potential future space weather sentinels. We present a proposal to redirect the Genesis spacecraft after its prime mission is complete, and create a new, inexpensive mission: EXODUS.

  14. Genesis of the central zone of the Nolans Bore rare earth element deposit, Northern Territory, Australia

    NASA Astrophysics Data System (ADS)

    Schoneveld, Louise; Spandler, Carl; Hussey, Kelvin

    2015-08-01

    The Nolans Bore rare earth element (REE) deposit consists of a network of fluorapatite-bearing veins and breccias hosted within Proterozoic granulites of the Reynolds Range, Central Australia. Mineralisation is divided into three zones (north, central, and south-east), with the north and south-east zones consisting of massive REE-bearing fluorapatite veins, with minor brecciation and carbonate infill. The central zone is distinctively different in mineralogy and structure; it features extensive brecciation, a high allanite content, and a large, epidote-rich enveloping alteration zone. The central zone is a reworking of the original solid apatite veins that formed during the Chewings Orogeny at ca. 1525 Ma. These original apatite veins are thought to derive from phosphate-rich magmatic-hydrothermal fluid exsolved from as-yet unrecognised alkaline magmatic bodies at depth. We define four ore breccia types (BX1-4) in the central zone on the basis of detailed petrological and geochemical analysis of drillcore and thin sections. BX1 ore comprises fluorapatite with minor crackle brecciation with carbonate infill and resembles ore of the north and south-east zones. Breccia types BX2, BX3, and BX4 represent progressive stages of ore brecciation and development of calc-silicate mineral (amphibole, epidote, allanite, calcite) infill. Comparison of bulk ore sample geochemistry between breccia types indicates that REEs were not mobilised more than a few centimetres during hydrothermal alteration and brecciation. Instead, most of the REEs were partitioned from the original REE fluorapatite into newly formed allanite, REE-poor fluorapatite and minor REE carbonate in the breccias. Negative europium (Eu) anomalies in the breccia minerals are accounted for by a large positive Eu anomaly in epidote from the alteration zones surrounding the ore breccias. This observation provides a direct link between ore recrystallisation and brecciation, and the formation of the alteration halo in

  15. Depth profiling analysis of solar wind helium collected in diamond-like carbon film from Genesis

    DOE PAGES

    Bajo, Ken-ichi; Olinger, Chad T.; Jurewicz, Amy J.G.; ...

    2015-01-01

    The distribution of solar-wind ions in Genesis mission collectors, as determined by depth profiling analysis, constrains the physics of ion solid interactions involving the solar wind. Thus, they provide an experimental basis for revealing ancient solar activities represented by solar-wind implants in natural samples. We measured the first depth profile of ⁴He in a collector; the shallow implantation (peaking at <20 nm) required us to use sputtered neutral mass spectrometry with post-photoionization by a strong field. The solar wind He fluence calculated using depth profiling is ~8.5 x 10¹⁴ cm⁻². The shape of the solar wind ⁴He depth profile ismore » consistent with TRIM simulations using the observed ⁴He velocity distribution during the Genesis mission. It is therefore likely that all solar-wind elements heavier than H are completely intact in this Genesis collector and, consequently, the solar particle energy distributions for each element can be calculated from their depth profiles. Ancient solar activities and space weathering of solar system objects could be quantitatively reproduced by solar particle implantation profiles.« less

  16. Genesis Solar Wind Interstream, Coronal Hole and Coronal Mass Ejection Samples: Update on Availability and Condition

    NASA Technical Reports Server (NTRS)

    Allton, J. H.; Gonzalez, C. P.; Allums, K. K.

    2017-01-01

    Recent refinement of analysis of ACE/SWICS data (Advanced Composition Explorer/Solar Wind Ion Composition Spectrometer) and of onboard data for Genesis Discovery Mission of 3 regimes of solar wind at Earth-Sun L1 make it an appropriate time to update the availability and condition of Genesis samples specifically collected in these three regimes and currently curated at Johnson Space Center. ACE/SWICS spacecraft data indicate that solar wind flow types emanating from the interstream regions, from coronal holes and from coronal mass ejections are elementally and isotopically fractionated in different ways from the solar photosphere, and that correction of solar wind values to photosphere values is non-trivial. Returned Genesis solar wind samples captured very different kinds of information about these three regimes than spacecraft data. Samples were collected from 11/30/2001 to 4/1/2004 on the declining phase of solar cycle 23. Meshik, et al is an example of precision attainable. Earlier high precision laboratory analyses of noble gases collected in the interstream, coronal hole and coronal mass ejection regimes speak to degree of fractionation in solar wind formation and models that laboratory data support. The current availability and condition of samples captured on collector plates during interstream slow solar wind, coronal hole high speed solar wind and coronal mass ejections are de-scribed here for potential users of these samples.

  17. Molecular Substrate Alteration by Solar Wind Radiation Documented on Flown Genesis Mission Array Materials

    NASA Technical Reports Server (NTRS)

    Calaway, Michael J.; Stansbery, Eileen K.

    2006-01-01

    The Genesis spacecraft sampling arrays were exposed to various regimes of solar wind during flight that included: 313.01 days of high-speed wind from coronal holes, 335.19 days of low-speed inter-stream wind, 191.79 days of coronal mass ejections, and 852.83 days of bulk solar wind at Lagrange 1 orbit. Ellipsometry measurements taken at NASA s Johnson Space Center show that all nine flown array materials from the four Genesis regimes have been altered by solar wind exposure during flight. These measurements show significant changes in the optical constant for all nine ultra-pure materials that flew on Genesis when compared with their non-flight material standard. This change in the optical constant (n and k) of the material suggests that the molecular structure of the all nine ultra-pure materials have been altered by solar radiation. In addition, 50 samples of float-zone and czochralski silicon bulk array ellipsometry results were modeled with an effective medium approximation layer (EMA substrate layer) revealing a solar radiation molecular damage zone depth below the SiO2 native oxide layer ranging from 392 to 613 . This bulk solar wind radiation penetration depth is comparable to the depth of solar wind implantation depth of Mg measured by SIMS and SARISA.

  18. NR2A contributes to genesis and propagation of cortical spreading depression in rats

    PubMed Central

    Bu, Fan; Du, Ruoxing; Li, Yi; Quinn, John P; Wang, Minyan

    2016-01-01

    Cortical spreading depression (CSD) is a transient propagating excitation of synaptic activity followed by depression, which is implicated in migraine. Increasing evidence points to an essential role of NR2A-containing NMDA receptors in CSD propagation in vitro; however, whether these receptors mediate CSD genesis in vivo requires clarification and the role of NR2A on CSD propagation is still under debate. Using in vivo CSD in rats with electrophysiology and in vitro CSD in chick retina with intrinsic optical imaging, we addressed the role of NR2A in CSD. We demonstrated that NVP-AAM077, a potent antagonist for NR2A-containing receptors, perfused through microdialysis probes, markedly reduced cortex susceptibility to CSD, but also reduced magnitude of CSD genesis in rats. Additionally, NVP-AAM077 at 0.3 nmol perfused into the contralateral ventricle, considerably suppressed the magnitude of CSD propagation wave and propagation rate in rats. This reduction in CSD propagation was also observed with TCN-201, a negative allosteric modulator selective for NR2A, at 3 μM, in the chick retina. Our data provides strong evidence that NR2A subunit contributes to CSD genesis and propagation, suggesting drugs selectively antagonizing NR2A-containing receptors might constitute a highly specific strategy treating CSD associated migraine with a likely better safety profile. PMID:27001011

  19. Molecular Contamination on Anodized Aluminum Components of the Genesis Science Canister

    NASA Technical Reports Server (NTRS)

    Burnett, D. S.; McNamara, K. M.; Jurewicz, A.; Woolum, D.

    2005-01-01

    Inspection of the interior of the Genesis science canister after recovery in Utah, and subsequently at JSC, revealed a darkening on the aluminum canister shield and other canister components. There has been no such observation of film contamination on the collector surfaces, and preliminary spectroscopic ellipsometry measurements support the theory that the films observed on the anodized aluminum components do not appear on the collectors to any significant extent. The Genesis Science Team has made an effort to characterize the thickness and composition of the brown stain and to determine if it is associated with molecular outgassing.Detailed examination of the surfaces within the Genesis science canister reveals that the brown contamination is observed to varying degrees, but only on surfaces exposed in space to the Sun and solar wind hydrogen. In addition, the materials affected are primarily composed of anodized aluminum. A sharp line separating the sun and shaded portion of the thermal closeout panel is shown. This piece was removed from a location near the gold foil collector within the canister. Future plans include a reassembly of the canister components to look for large-scale patterns of contamination within the canister to aid in revealing the root cause.

  20. NR2A contributes to genesis and propagation of cortical spreading depression in rats.

    PubMed

    Bu, Fan; Du, Ruoxing; Li, Yi; Quinn, John P; Wang, Minyan

    2016-03-22

    Cortical spreading depression (CSD) is a transient propagating excitation of synaptic activity followed by depression, which is implicated in migraine. Increasing evidence points to an essential role of NR2A-containing NMDA receptors in CSD propagation in vitro; however, whether these receptors mediate CSD genesis in vivo requires clarification and the role of NR2A on CSD propagation is still under debate. Using in vivo CSD in rats with electrophysiology and in vitro CSD in chick retina with intrinsic optical imaging, we addressed the role of NR2A in CSD. We demonstrated that NVP-AAM077, a potent antagonist for NR2A-containing receptors, perfused through microdialysis probes, markedly reduced cortex susceptibility to CSD, but also reduced magnitude of CSD genesis in rats. Additionally, NVP-AAM077 at 0.3 nmol perfused into the contralateral ventricle, considerably suppressed the magnitude of CSD propagation wave and propagation rate in rats. This reduction in CSD propagation was also observed with TCN-201, a negative allosteric modulator selective for NR2A, at 3 μM, in the chick retina. Our data provides strong evidence that NR2A subunit contributes to CSD genesis and propagation, suggesting drugs selectively antagonizing NR2A-containing receptors might constitute a highly specific strategy treating CSD associated migraine with a likely better safety profile.

  1. Petrology, major and trace element geochemistry, geochronology, and isotopic composition of granitic intrusions from the vicinity of the Bosumtwi impact crater, Ghana

    NASA Astrophysics Data System (ADS)

    Losiak, Anna; Schulz, Toni; Buchwaldt, Robert; Koeberl, Christian

    2013-09-01

    The Bosumtwi crater is 10.5 km in diameter, 1.07 Ma old, well preserved impact structure located in Ghana (centered at 06°30‧N, 01°25‧W). It was excavated in rocks of the Early Proterozoic Birimian Supergroup, part of the West African craton. Here, we present a full and detailed characterization of the three granitoid complexes and one mafic dike in the vicinity of the Bosumtwi crater in terms of petrology, major and trace element geochemistry, geochronology, and isotopic composition. This allows us to characterize magmatic evolution of the West African Craton in this area and better understand the geological framework and target rocks of the impact. This study shows that the similar composition (strongly peraluminous muscovite granites and granodiorites) and age (between 2092 ± 6 Ma and 2098 ± 6 Ma) of all granitic intrusions in the proximity of the Bosumtwi crater suggest that they are co-genetic. Granitoids were probably formed as a result of anatexis of TTGs (or rocks derived from them) at relatively low pressure and temperature. We propose that the intrusions from the Bosumtwi area are genetically related to the Banso granite occurring to the east of the crater and can be classified as basin-type, late-stage granitoids. Also a mafic dike located to the NE of the Bosumtwi crater seems to be genetically related to those felsic intrusions. Based on those findings a revised version of the geological map of the Bosumtwi crater area is proposed.

  2. Weathering of Igneous, Metamorphic, and Sedimentary Rocks in a Semi-arid Climate - An Engineering Application of Petrology

    NASA Astrophysics Data System (ADS)

    Harrison, W. J.; Wendlandt, R. F.

    2003-12-01

    Over the last 10 years, analytical methods have been introduced to students in CSM's undergraduate geological engineering program through a multi-year and multi-course approach. Beginning with principles and simple applications of XRD and SEM in sophomore Mineralogy and building on these skills in subsequent junior and senior year courses, geological engineers acquire proficiency in analytical methods. Essential workplace skills are thus acquired without adding an extra course in the undergraduate program. The following exercise is completed by juniors in an integrated Ig.-Met.-Sed. petrology course. The identification of clay mineral assemblages in soils provides a unique opportunity to demonstrate how basic principles of petrology and geochemistry are applied to engineering design criteria in construction site preparation. Specifically, the problem investigates the conditions leading to the formation of smectite in soils and the resulting construction risk due to soil expansion. Students examine soils developed on igneous, metamorphic, and sedimentary rocks near Denver, Colorado. The field locations are areas of suburban growth and several have expansive soil problems. The 2-week exercise includes sample collection, description, and preparation, determining clay mineralogy by XRD, and measurement of Atterberg Plasticity Indices. Teaching materials may be found at: http://serc.carleton.edu/NAGTWorkshops/petrology03/. This exercise accomplishes three objectives: First, skills in XRD analysis are developed by introducing students to concepts of particle size separation, particle orientation, and sequential analysis steps which are standard practices in clay characterization. Second, lecture material on the geochemistry of weathering of different rock types is reinforced. Students interpret the origin of clay mineral assemblages developed in soils derived from Precambrian gneisses, lower Paleozoic feldspathic sandstones, upper Paleozoic marine shales, and Tertiary

  3. Geochemistry and petrology of Oligocene and Miocene ash-flow tuffs of the southeastern Great Basin, Nevada

    USGS Publications Warehouse

    du Bray, Edward A.

    1995-01-01

    The White River Narrows area of Southeast Nevada contains 18 regionally distributed middle Tertiary dacite to rhyolite ash-flow tuffs. Geochemical data provide an excellent opportunity to study stratigraphic and petrologic relations of these tuffs. Chemical data for each of the tuffs are distinctive and provide a significant addition to other data used to identify and correlate these units. Relatively minor compositional variation within the tuffs is noteworthy.

  4. Petrological insights into intermediate-depths of a subduction plate interface

    NASA Astrophysics Data System (ADS)

    Angiboust, Samuel; Agard, Philippe

    2013-04-01

    Understanding processes acting along the subduction interface is crucial to assess lithospheric scale coupling between tectonic plates, exhumation of deep-seated rocks and mechanisms causing intermediate-depth seismicity. Yet, despite a wealth of geophysical studies aimed at better characterizing the subduction interface, we still lack critical petrological data constraining such processes as intermediate-seismicity within oceanic subduction zones. This contribution reviews recent findings from two major localities showing deeply subducted ophiolitic remnants (Zermatt-Saas, Monviso), which crop out in the classic, well-preserved fossil subduction setting of the Western Alps. We herein show that both ophiolite remnants represent large, relatively continuous fragments of oceanic lithosphere (i.e., several km-thick tectonic slices across tens of km) exhumed from ~80 km depths and thereby provide important constraints on interplate coupling mechanisms. In both fragments (but even more so in the Zermatt-Saas one) pervasive hydrothermal processes and seafloor alteration, promoting fluid incorporation in both mafic and associated ultramafic rocks, was essential, together with the presence of km-thick serpentinite soles, to decrease the density of the tectonic slices and prevent them from an irreversible sinking into the mantle. The Monviso case sudy provides further insights into the subduction plate interface at ~80 km depths. The Lago Superiore Unit, in particular, is made of a 50-500 m thick eclogitized mafic crust (associated with minor calcschist lenses) overlying a 100-400 m thick metagabbroic body and a km-thick serpentinite sole, and is cut by two 10 to 100m thick eclogite-facies shear zones, respectively located at the boundary between basalts and gabbros, and between gabbros and serpentinites (the Lower Shear Zone: LSZ). The LSZ gives precious information on both seismicity and fluid flow: (1) Eclogite breccias, reported here for the first time, mark the locus

  5. Application of Automated SEM-EDS Based Mineral Identification Systems to Problems in Metamorphic Petrology

    NASA Astrophysics Data System (ADS)

    Fairhurst, Robert; Barrow, Wendy; Rollinson, Gavyn

    2010-05-01

    Automated scanning electron microscopy-energy dispersive x-ray spectrometer (SEM-EDS) based mineral identification systems such as QEMSCAN have been in development for over 20 years, primarily as a tool to understand mineral liberation and element distribution in metal mining industry. This powerful technique is now being used in non mining applications such as metamorphic petrology where accurate mineral identification and metamorphic fabrics are key to deciphering the metamorphic history of samples. The QEMSCAN was developed by CSIRO for application in the mining industry where it is used to understand mineralogy, texture, mineral associations, the presence of gangue minerals and deleterious elements that may potentially interfere with mineral processing and planning, and the overall impact of mineralogy on grinding and flotation processes. It is capable of identifying most rock-forming minerals in milliseconds from their characteristic x-ray spectra. The collected x-ray spectra are compared to entries in a database containing the species identification profiles (SIPs) and are assigned a label accordingly. QEMSCAN is capable of searching large sample areas at high resolution resulting in the accurate and precise determination of all minerals present. Reports that were originally developed for the mining geologist can be equally useful to the petrologist, e.g. phase/mineral maps, modal mineral abundances and mineral association reports. Identification of key minerals is of great importance to determining the petrologic history of a sample. These key minerals may be few in number and present as small microinclusions (less than 100 μm) making them difficult to identify, if at all, with the petrographic microscope. Therefore, imaging by electron-microprobe or scanning electron microscope are the methods traditionally used. However, because of the small field of view available on these instruments at a magnification necessary to resolve micron sized relicts and

  6. Petrologic model of the northern Mississippi Embayment based on satellite magnetic and ground-based geophysical data

    NASA Technical Reports Server (NTRS)

    Thomas, H. H.

    1984-01-01

    A petrologic model of the northern Mississippi Embayment, derived from gravity, seismic and rift data, is evaluated by converting the model to a magnetization model which is compared with satellite magnetic anomaly models. A magnetization contrast of approximately -0.54 A/m, determined from the petrologic model of the embayment compares favorably to values of -0.62 A/m and -0.45 A/m from a Magsat United States Apparent Magnetization Contrast Map and a published POGO magnetization contrast model, respectively. The petrologic model suggests that the magnetic anomaly low associated with the Mississippi Embayment may be largely due to the intrusion under non-oxidizing conditions of low Curie temperature gabbroic material at the base of the crust of the embayment. Near-surface mafic plutons, bordering the Mississippi Valley Graben, appear from aeromagnetic data to have higher magnetizations than the deeper gabbroic material; however, it is impossible to ascertain if this is due to compositional differences or similar material at shallower (lower temperature) depths. These results indicate that variations in the Curie temperatures of intrusions accompanying rifting may account for a large part of the wide range of magnetic anomalies associated with presently inactive rifts with normal heat flow.

  7. A new approach to the problem of tektite genesis

    NASA Astrophysics Data System (ADS)

    Bentor, Y. K.

    1986-02-01

    Variations in the composition of tektites and microtektites in different strewn fields are discussed. The effects of SiO2 on the Niggli parameters is investigated. It is observed that as SiO2 increases the proportion of alumina and alkalies in the cations increases, MgO, and FeO decreases, and the CaO remains approximately constant. Data elucidating the cause of these chemical variations to be due to partial melting are examined. Variations in the chemistry of more complex systems such as moldavites and australites are analyzed by reducing the variation diagrams to two-five lineages of the simpler type. The relationship between tektites and parent rocks is studied. The results reveal that the silica-poorest tektites of each variation diagram provide the correlation between the parent rock and the tektite composition.

  8. Origins of cratonic mantle discontinuities: A view from petrology, geochemistry and thermodynamic models

    NASA Astrophysics Data System (ADS)

    Aulbach, Sonja; Massuyeau, Malcolm; Gaillard, Fabrice

    2017-01-01

    Geophysically detectible mid-lithospheric discontinuities (MLD) and lithosphere-asthenosphere boundaries (LAB) beneath cratons have received much attention over recent years, but a consensus on their origin has not yet emerged. Cratonic lithosphere composition and origin is peculiar due to its ultra-depletion during plume or accretionary tectonics, cool present-day geothermal gradients, compositional and rheological stratification and multiple metasomatic overprints. Bearing this in mind, we integrate current knowledge on the physical properties, chemical composition, mineralogy and fabric of cratonic mantle with experimental and thermodynamic constraints on the formation and migration of melts, both below and within cratonic lithosphere, in order to find petrologically viable explanations for cratonic mantle discontinuities. LABs characterised by strong seismic velocity gradients and increased conductivity require the presence of melts, which can form beneath intact cratonic roots reaching to 200-250 km depth only in exceptionally warm and/or volatile-rich mantle, thus explaining the paucity of seismical LAB observations beneath cratons. When present, pervasive interaction of these - typically carbonated - melts with the deep lithosphere leads to densification and thermochemical erosion, which generates topography at the LAB and results in intermittent seismic LAB signals or conflicting seismic, petrologic and thermal LAB depths. In rare cases (e.g. Tanzanian craton), the tops of live melt percolation fronts may appear as MLDs and, after complete lithosphere rejuvenation, may be sites of future, shallower LABs (e.g. North China craton). Since intact cratons are presently tectonomagmatically quiescent, and since MLDs produce both positive and negative velocity gradients, in some cases with anisotropy, most MLDs may be best explained by accumulations (metasomes) of seismically slow minerals (pyroxenes, phlogopite, amphibole, carbonates) deposited during past

  9. Radio-induced alteration in cordierite - Implications for petrology, gemmology and materials science

    NASA Astrophysics Data System (ADS)

    Krickl, R.; Nasdala, L.; Grambole, D.; Kaindl, R.

    2009-04-01

    Cordierite is a common metamorphic and magmatic mineral, which is used as petrologic tool for reconstructing the history of its host rock. Further applications include cordierite gemstones and the use of synthetic analogs in ceramics. Cordierite is stable over a wide temperature and pressure range and relatively resistant to chemical alteration; however, its properties can be significantly changed upon the impact of external irradiation. In the course of a comprehensive study, natural radiohaloes in cordierite (a widespread feature caused by the impact of alpha-particles originating from radioactive inclusions) as well as artificial analogs produced by implantation of 8.8 MeV He2+ ions were investigated using modern micro-techniques. Additional irradiation experiments were performed using O6+ ions, electrons and gamma-rays. Ion irradiation causes yellow colouration that is strongly pleochroic, and fades at higher doses. The possibility of radiation-treatment for enhancing the quality of gem-cordierite is discussed. While samples remain crystalline up to doses of 1016 He2+/cm2, the same material is fully amorphised when irradiated with the same dose of 30 MeV O6+ ions. These different observations may help to estimate the performance assessment of cordierite-ceramics in radiated environments. A very important result concerning the petrological use of cordierite is the radio-induced transformation of channel constituents: Inside the irradiated areas the vibrational bands of CO2 decrease in intensity, whereas two new bands appear at 2135 cm-1 (both IR- and Raman-active; cf. Nasdala et al., 2006) and 1550 cm-1 (only Raman-activ). They are assigned to stretching vibrations of carbon monoxide and molecular oxygen, respectively, thus indicating a radio-chemical transformation 2CO2 → 2CO + O2 in alpha-irradiated cordierite. This study yields the first spectroscopic evidence for the irradiation-induced formation of molecular oxygen in cordierite. Polarised vibrational

  10. Petrological and geochemical data of volcanic rocks from the southern Afar Depression, Ethiopia.

    NASA Astrophysics Data System (ADS)

    Urbanek, Ch.; Faupl, P.; Richter, W.; Seidler, H.

    2003-04-01

    The geological and petrological investigations (FWF Project P15196) in the southern Afar Depression of Ethiopia support an international palaeoanthropological research-team (PAR) under the leadership of Horst Seidler. Mount Galila is the conspicuous centre of the research area [N 9° 44.101', E 40° 27.368'], situated about 20 km E of the NNE-SSW striking, recently active Hertale Graben, which represents a northernmost segment of the Main Ethiopian Rift (MER). Stratigraphically, the fossiliferous lacustrine and fluvial deposits, as well as the intercalated volcanic layers of the Galila area, belong to the "Upper Stratoid Series" (5-1.4 Ma) and will be named the Mount Galila Formation. They are similar to the Awash Group, from which very famous early hominid fossils have been described. In the Mount Galila Fm., 7 main volcanic horizons serve as marker beds comprising basalts, ignimbrites, tuffs and tuffaceous sands. The basalt horizons in the research area represent basaltic lava flows each consisting of one single flow unit c. 5 meters thick with maximum 5 cooling units. A first set of geochemical data from XRF spectrometry comprising main and trace element analysis shows characteristics for the volcanic marker beds as following: The basalts are clearly tholeiitic in the main elements (FeO/MgO/Alk) and show typical trace element distributions (e.g. Zr/Y-Zr; Ti/100-Yx3-Zr) as Within Plate Tholeiit Basalts. All basalt samples contain access 40Ar which can be explained by specific erruption mechanisms that leads to analytical problems for 40Ar/39Ar dating. In the TAS diagram after LeMaitre 1984 the ignimbrites vary at high alkali levels (7-9%) from trachytic to dacitic and rhyolitic composition, whereas at low alkali contents (<7%) they plot into the andesitic field. Compared to the basalts, the geochemistry of the ignimbrites is much more inhomogenous. Tuffs and tuffaceous sands are relevant as marker beds especially for the palaeoanthropological excavations in the

  11. Petrology and Geochemistry of the Northeast Seamounts of the Galapagos Platform

    NASA Astrophysics Data System (ADS)

    Sinton, C. W.; Harpp, K. S.; Christie, D. M.

    2010-12-01

    One of the best locations to study hotspot-ridge interactions is the Northern Galápagos Province (NGP), the region that lies between the Galapagos Spreading Center (GSC) and the central portion of the Galapagos Archipelago. The Galapagos hotspot is currently located off-axis from the GSC but still has a profound influence on the ridge in terms of axial lava composition and ridge bathymetry. The NGP is characterized by an array of volcanic lineaments that are composed of seamounts and five small islands. The eastern edge of the NGP is defined by a group of at least five seamounts (the Northeast Seamounts), three of which were mapped and dredged in 1990 during Leg 2 of the PLUME expedition of the R/V Thomas Washington. We report petrological and geochemical data from the basalts recovered at six dredge sites. All basalts are tholeiitic with a general MORB-like composition, but with considerable variation within some individual dredge hauls and between seamounts. Previously published isotopic data are limited but 3He/4He ratios (Graham et al. 1993) and Sr-Nd-Pb isotopic data (Harpp and White 2000) are consistent with a depleted mantle source for all three seamounts. Based on geochemistry and petrological observations, the basalts can be divided into at least thirteen distinct groups. The bulk of the analyzed glass samples have compositions more than MORB with MgO content of 8-10% wt., although two of the groups are in the 6-7% range. In addition, the primitive lavas have high CaO and Al2O3 . The mineralogy ranges from aphyric for the more evolved lavas to olivine + plagioclase-phyric or plagioclase ultraphyric for the more primitive basalts. The plagioclase appear to be very calcic (up to An91) xenocrysts that are often hosting aluminous spinel (Al2O3 46-48% wt.) and primitive melt inclusions (Sinton et al., 1993). Initial trace element data show light rare earth (LREE)-depleted signatures, although several samples are slightly enriched in the LREE. Taken together

  12. Evolution of the Taupo Volcanic Center, New Zealand: petrological and thermal constraints from the Omega dacite

    NASA Astrophysics Data System (ADS)

    Gelman, Sarah E.; Deering, Chad D.; Gutierrez, Francisco J.; Bachmann, Olivier

    2013-11-01

    The 20 ka ~0.1 km3 Omega dacite, which erupted shortly after the 26.5 ka Oruanui super-eruption, compositionally stands out among Taupo Volcanic Zone (TVZ) magmas, which are overwhelmingly characterized by rhyolites (>90 % by volume). The previously reported presence of inherited zircons in this zircon-undersaturated magma has provided unequivocal evidence for the involvement of upper-crustal material in a 1-10 year timescale prior to the Omega eruption. However, whether this crustal involvement is characterized by wholesale, melting of preexisting crust or subordinate bulk assimilation into an already differentiated magma body remains unclear. To disentangle these processes, we describe the mineral chemistry of the major phases present in the Omega dacite and determine intensive parameters describing magma chamber conditions. Dominantly unimodal populations of plagioclase (An50-60), orthopyroxene (Mg# from 58 to 68), and clinopyroxene (Mg# from 65 to 73), along with coexisting equilibrium pairs of Fe-Ti oxides, constrain pre-eruptive temperatures to 850-950 °C, a pressure between ~3 and 7 kbars, and an oxygen fugacity of ~NNO. MELTS thermodynamic modeling suggests that this phase assemblage is in equilibrium with the bulk rock and glass compositions of the Omega dacite at these estimated P- T- fO2 pre-eruptive conditions. Combining these petrological observations with insights into conductive thermal models of magma-crust interactions, we argue that the Omega dacite more likely formed in the mid-to-lower crust via protracted processing through fractional crystallization coupled with some assimilation (AFC). Incorporation of crustal material is likely to have occurred at various stages, with the inherited zircons (and potentially parts of glomerocrysts) representing late and subordinate upper-crustal assimilants. This petrogenetic model is consistent with the presence of a differentiating crustal column, consisting of a polybaric fractional crystallization and

  13. Core petrology: Implications for the dynamics and evolution of planetary interiors

    NASA Astrophysics Data System (ADS)

    Hauck, S. A.; Van Orman, J. A.

    2011-12-01

    the cores of the smaller terrestrial bodies in the Solar System are readily accessible in the laboratory, and allow systematic study of the petrologic behavior of the wide range of possible core systems. We discuss the potential consequences of core petrologic evolution for magnetic field generation and prospects for future progress in constraining the operation of planetary cores.

  14. The added value of biomarker analysis to the genesis of Plaggic Anthrosols.

    NASA Astrophysics Data System (ADS)

    van Mourik, Jan; Jansen, Boris

    2015-04-01

    Coversands (chemical poor Late-glacial aeolian sand deposits) dominate the surface geology of an extensive area in northwestern Europe. Plaggic Anthrosols occur in cultural landscapes, developed on coversands. They are the characteristic soils that developed on ancient fertilized arable fields. Plaggic Anthrosols have a complex genesis. They are records of aspects environmental and agricultural history. In previous studies information of the soil records was unlocked by application of pollen analysis, 14C and OSL dating. In this study we applied biomarker analysis to unlock additional information about the applied organic sources in the production of plaggic manure. Radiocarbon dating suggested the start of sedentary agriculture (after a period, characterized by shifting cultivation and Celtic fields) between 3000 and 2000 BP. In previous studies is assumed that farmers applied organic sods, dug on forest soils and heath to produce organic stable manure to fertilize the fields. The mineral fraction of the sods was supposed to be responsible for the development of the plaggic horizon and the raise of the land surface. Optically stimulated Luminescence dating however suggested that plaggic deposition on the fields started relatively late, in the 18th century. The use of ectorganic matter from the forest soils must have been ended in the 10th-12th century, due to commercial forest clear cuttings as recorded in archived documents. These deforestations resulted in the first extension of sand drifting and famers had to protect the valuable heath against this ' environmental catastrophe' . The use of heath for sheep grazing and other purposes as honey production could continue till the 18th century, as recorded in archived documents. In the course of the 18th century, the population growth resulted in increasing demand for food. The deep stable economy was introduced and the booming demand for manure resulted in intensive sod digging on the heath. This caused heath

  15. Cryogenian alkaline magmatism in the Southern Granulite Terrane, India: Petrology, geochemistry, zircon U-Pb ages and Lu-Hf isotopes

    NASA Astrophysics Data System (ADS)

    Santosh, M.; Yang, Qiong-Yan; Ram Mohan, M.; Tsunogae, T.; Shaji, E.; Satyanarayanan, M.

    2014-11-01

    The Southern Granulite Terrane (SGT) in India preserves the records of the formation and recycling of continental crust from Mesoarchean through Paleoproterozoic to Neoproterozoic and Cambrian, involving multiple subduction-accretion-collision associated with major orogenic cycles. A chain of unmetamorphosed and undeformed alkaline magmatic intrusions occurs along the northern margin of the SGT aligned along paleo-suture zones. Here we investigate two representative plutons from this suite, the Angadimogar syenite (AM) and the Peralimala alkali granite (PM) through field, petrological, geochemical, zircon U-Pb and Lu-Hf studies. Magma mixing and mingling textures and mineral assemblages typical of alkaline rocks are displayed by these plutons. The whole-rock major and trace element data characterize their alkaline nature. In trace element discrimination diagrams, the AM rocks straddle between the VAG (volcanic-arc granites) and WPG (within plate granites) fields with most of the samples confined to the VAG field, whereas the PM rocks are essentially confined to the WPG field. The diversity in some of the geochemical features between the two plutons is interpreted to be the reflection of source heterogeneities. Most zircon grains from the AM and PM plutons display oscillatory zoning typical of magmatic crystallization although some grains, particularly those from the PM pluton, show core-rim structures with dark patchy zoned cores surrounded by irregular thin rims resulting from fluid alteration. The weighted mean 206Pb/238U ages of the magmatic zircons from three samples of the AM syenite are in the range of 781.8 ± 3.8 Ma to 798 ± 3.6 Ma and those from two samples of the PM alkali granite yield ages of 797.5 ± 3.7 Ma and 799 ± 6.2 Ma. A mafic magmatic enclave from the AM pluton shows weighted mean 206Pb/238U age of 795 ± 3.3 Ma. The AM and PM plutons also carry rare xeneocrystic zircons which define upper intercept concordia ages of 3293 ± 13 Ma and 2530

  16. [Interaction of work demands in the genesis of mental suffering].

    PubMed

    Noriega, M; Laurell, C; Martínez, S; Méndez, I; Villegas, J

    2000-01-01

    Current working conditions and new forms of work organization are affecting workers' health in numerous ways which can only be explained by more complex theories and methodologies than those used traditionally. The authors analyze some important elements of the work process and the interaction among work demands as determinants of mental and psychosomatic disorders and fatigue (MPDF) among workers in a Mexican industrial plant. The workers studied (n = 830) were male, with a mean age of 32. MPDF represent one-third of the disease burden among these workers. An association was observed with the number of years worked, type of activity, and job area. Job-related demands and work organization, including excessive work, strict supervision, dangerous work, unnatural positions, and intense and hard physical labor were also closely related to these conditions. The most relevant problem is the combination of many different demands. Interaction among the combinations was found to be additive or synergistic. In the latter condition the risk of morbid effects increases beyond merely an additive effect.

  17. Genesis and morphogenesis of limb synovial joints and articular cartilage.

    PubMed

    Decker, Rebekah S; Koyama, Eiki; Pacifici, Maurizio

    2014-10-01

    Limb synovial joints are intricate structures composed of articular cartilage, synovial membranes, ligaments and an articular capsule. Together, these tissues give each joint its unique shape, organization and biomechanical function. Articular cartilage itself is rather complex and organized in distinct zones, including the superficial zone that produces lubricants and contains stem/progenitor cells. For many years there has been great interest in deciphering the mechanisms by which the joints form and come to acquire such unique structural features and diversity. Decades ago, classic embryologists discovered that the first overt sign of joint formation at each prescribed limb site was the appearance of a dense and compact population of mesenchymal cells collectively called the interzone. Work carried out since then by several groups has provided evidence that the interzone cells actively participate in joint tissue formation over developmental time. This minireview provides a succinct but comprehensive description of the many important recent advances in this field of research. These include studies using various conditional reporter mice to genetically trace and track the origin, fate and possible function of joint progenitor cells; studies on the involvement and roles in signaling pathways and transcription factors in joint cell determination and functioning; and studies using advanced methods of gene expression analyses to uncover novel genetic determinants of joint formation and diversity. The overall advances are impressive, and the findings are not only of obvious interest and importance but also have major implications in the conception of future translational medicine tools to repair and regenerate defective, overused or aging joints.

  18. MoonDB: Restoration and Synthesis of Lunar Petrological and Geochemical Data

    NASA Technical Reports Server (NTRS)

    Lehnert, Kerstin A.; Cai, Yue; Mana, Sara; Todd, Nancy S.; Zeigler, Ryan A.; Evans, Cindy A.

    2016-01-01

    About 2,200 samples were collected from the Moon during the Apollo missions, forming a unique and irreplaceable legacy of the Apollo program. These samples, obtained at tremendous cost and great risk, are the only samples that have ever been returned by astronauts from the surface of another planetary body. These lunar samples have been curated at NASA Johnson Space Center and made available to the global research community. Over more than 45 years, a vast body of petrological, geochemical, and geochronological studies of these samples have been amassed, which helped to expand our understanding of the history and evolution of the Moon, the Earth itself, and the history of our entire solar system. Unfortunately, data from these studies are dispersed in the literature, often only available in analog format in older publications, and/or lacking sample metadata and analytical metadata (e.g., information about analytical procedure and data quality), which greatly limits their usage for new scientific endeavors. Even worse is that much lunar data have never been published, simply because no forum existed at the time (e.g., electronic supplements). Thousands of valuable analyses remain inaccessible, often preserved only in personal records, and are in danger of being lost forever, when investigators retire or pass away. Making these data and metadata publicly accessible in a digital format would dramatically help guide current and future research and eliminate duplicated analyses of precious lunar samples.

  19. CM chondrites exhibit the complete petrologic range from type 2 to 1. [Abstract only

    NASA Technical Reports Server (NTRS)

    Zolensky, M. E.; Browning, L. B.

    1994-01-01

    Recognition and characterization of the different CM lithologies as components in all meteorites could reveal details of the nature and chronology of alteration and brecciation events on hydrous asteroids. The CM chondrites are of particular interest, as they are the most common carbonaceous chondrites and are found as clasts within other types of meteorites, which suggests that the CM parent asteroids are (or were) widespread in the sections of the asteroid belt providing samples to Earth. Some CM2s, including EET 90047, ALH 83100, and Y 82042, are more 'extensively' altered, and are distinguished by a high proportion of Mg-rich phyllosilicates and Ca-Mg carbonates, frequently in rounded aggregates, and near absence of olivine or pyroxene. 'Completely' altered CMs, called CM1s, essentially lack olivine or pyroxene; these include EET 83334, ALH 88045, and the CM1 clasts in Kaidun. Cold Bokkeveld and EET 84034, both highly brecciated CMs, consist of both extensively and completely altered lithologies. We describe how these lithologies further cosntrain physicochemical conditions on hydrous asteroids. We conclude that CM chondrites exhibit the petrologic range 2 through 1, and that progressive alteration on the parent hydrous asteroid(s) was accompanied by significant increases in temperature (to a peak of approximately 450 C), fO2, water-rock ratio, and (locally) degree of chemical leaching, all well beyond the conditions recorded by CM2s.

  20. Core facies, petrology, and permeability of Tirrawarra Sandstone, Moorari Field, Cooper Basin, South Australia

    SciTech Connect

    Bever, J.M.; Carroll, P.G.; Wild, E.W.; Williams, B.P.J.

    1988-01-01

    The oil and gas-bearing Tirrawarra Sandstone lies in the basal section of the Cooper basin sequence, which is largely Permian in age. The sandstone is characteristically thick, but both interfingers with and conformable overlies glacio-lacustrine diamictites and varvites of the late Carboniferous-Early Permian Merrimeleia Formation. The Tirrawarra Sandstone has previously been interpreted as being deposited in a glacio-fluvial braided river environment. The sandstone produces high gas:oil-ratio oil at the Moorari field, from depths of 9,400 ft below sea level. Appraisal and development of the field has been hampered by the patchy distribution of reservoir quality sandstone. This study investigated the cause of reservoir quality variations. For seven cored wells, core facies analysis, core plug porosity/permeability, petrology, and wireline logs were all matched and compared. The results are as follows. (1) Facies states (grain size and bed form) largely control permeability distribution in the Tirrawarra Sandstone at the Moorari field, such that horizontally bedded medium-coarse sandstones are consistently more permeable than cross-bedded equivalents. (2) Diagenesis levels are high and include extensive silica cement and patchy kaolinite and siderite cements. However, diagenesis rarely operates independently of original depositional fabric. (3) An association between depositional environment and permeability is recognizable, with medial bars in particular providing better reservoir quality.

  1. Geochemistry and petrology of selected coal samples from Sumatra, Kalimantan, Sulawesi, and Papua, Indonesia

    USGS Publications Warehouse

    Belkin, H.E.; Tewalt, S.J.; Hower, J.C.; Stucker, J.D.; O'Keefe, J. M. K.

    2009-01-01

    Indonesia has become the world's largest exporter of thermal coal and is a major supplier to the Asian coal market, particularly as the People's Republic of China is now (2007) and perhaps may remain a net importer of coal. Indonesia has had a long history of coal production, mainly in Sumatra and Kalimantan, but only in the last two decades have government and commercial forces resulted in a remarkable coal boom. A recent assessment of Indonesian coal-bed methane (CBM) potential has motivated active CBM exploration. Most of the coal is Paleogene and Neogene, low to moderate rank and has low ash yield and sulfur (generally < 10 and < 1??wt.%, respectively). Active tectonic and igneous activity has resulted in significant rank increase in some coal basins. Eight coal samples are described that represent the major export and/or resource potential of Sumatra, Kalimantan, Sulawesi, and Papua. Detailed geochemistry, including proximate and ultimate analysis, sulfur forms, and major, minor, and trace element determinations are presented. Organic petrology and vitrinite reflectance data reflect various precursor flora assemblages and rank variations, including sample composites from active igneous and tectonic areas. A comparison of Hazardous Air Pollutants (HAPs) elements abundance with world and US averages show that the Indonesian coals have low combustion pollution potential.

  2. Structural and petrologic characteristics of the Taconian-Acadian overprint zone in Massachusetts and Vermont

    SciTech Connect

    Armstrong, T.R. . Dept. of Geological Sciences); Hames, W.E. . Dept. of Earth, Atmospheric, and Planetary Sciences)

    1993-03-01

    Structural and petrologic relationships from two regions of the New England Taconide Zone provide distinction of Taconian and Acadian deformation fabrics and related metamorphisms. In SW Massachusetts, Taconian metamorphism increases eastward from chlorite- to kyanite-grade, with staurolite zone Zr hb plateau ages of [approx]445 Ma. Within the Acadian fibrolite zone, Ar cooling ages are related to a thermal maximum at 390--400Ma, coeval with crenulation cleavage that deforms Taconian fabrics. Taconian and Acadian metamorphic regimes are separated by a 4 km-wide zone in which polymetamorphic assemblages exist but yield consistent Acadian mineral-rim P-T data, and Acadian structures are pervasive. In southern Vermont, the overlap zone is broad ([approx]30 km); undisturbed Taconian Ar K-feldspar cooling ages occur on the west side of the Green Mountain massif. Farther east, Taconian fabric is almost completely obliterated by dynamic Acadian metamorphism, and is truncated and retrograded in areas adjacent to a major Acadian thrust zone. The upper plate rocks, including the Barnard Belt and the Silurian-Devonian sequences (the CVB), do not contain Taconian fabrics, the early Acadian deformations, or retrogression, and are associated with garnet-to-kyanite-grade Acadian metamorphism and a coeval, regionally dominant deformation, both of which are younger than 390Ma and older than 373Ma.

  3. Petrology of the Devonian gas-bearing shale along Lake Erie helps explain gas shows

    SciTech Connect

    Broadhead, R.F.; Potter, P.E.

    1980-11-01

    Comprehensive petrologic study of 136 thin sections of the Ohio Shale along Lake Erie, when combined with detailed stratigraphic study, helps explain the occurrence of its gas shows, most of which occur in the silty, greenish-gray, organic poor Chagrin Shale and Three Lick Bed. Both have thicker siltstone laminae and more siltstone beds than other members of the Ohio Shale and both units also contain more clayshales. The source of the gas in the Chagrin Shale and Three Lick Bed of the Ohio Shale is believed to be the bituminous-rich shales of the middle and lower parts of the underlying Huron Member of the Ohio Shale. Eleven petrographic types were recognized and extended descriptions are provided of the major ones - claystones, clayshales, mudshales, and bituminous shales plus laminated and unlaminated siltstones and very minor marlstones and sandstones. In addition three major types of lamination were identified and studied. Thirty-two shale samples were analyzed for organic carbon, whole rock hydrogen and whole rock nitrogen with a Perkin-Elmer 240 Elemental Analyzer and provided the data base for source rock evaluation of the Ohio Shale.

  4. Petrology and mineral chemistry of peraluminous Marziyan granites, Sanandaj-Sirjan metamorphic belt (NW Iran)

    NASA Astrophysics Data System (ADS)

    Darvishi, Esmaiel; Khalili, Mahmoud; Beavers, Roy; Sayari, Mohammad

    2015-10-01

    The Marziyan granites are located in the north of Azna and crop out in the Sanandaj-Sirjan metamorphic belt. These rocks contain minerals such as quartz, K-feldspars, plagioclase, biotite, muscovite, garnet, tourmaline and minor sillimanite. The mineral chemistry of biotite indicates Fe-rich (siderophyllite), low TiO2, high Al2O3, and low MgO nature, suggesting considerable Al concentration in the source magma. These biotites crystallized from peraluminous S-type granite magma belonging to the ilmenite series. The white mica is rich in alumina and has muscovite composition. The peraluminous nature of these rocks is manifested by their remarkably high SiO2, Al2O3 and high molar A/CNK (> 1.1) ratio. The latter feature is reflected by the presence of garnet and muscovite. All field observations, petrography, mineral chemistry and petrology evidence indicate a peraluminous, S-type nature of the Marziyan granitic rocks that formed by partial melting of metapelite rocks in the mid to upper crust possibly under vapour-absent conditions. These rocks display geochemical characteristics that span the medium to high-K and calc-alkaline nature and profound chemical features typical of syn-collisional magmatism during collision of the Afro-Arabian continental plate and the Central Iranian microplate.

  5. Petrological variability of recent magmatism at Axial Seamount summit, Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Dreyer, Brian M.; Clague, David A.; Gill, James B.

    2013-10-01

    A combined study of mapping, observational, age constraint, and geochemical data at the summit of Axial Seamount, Juan de Fuca Ridge, has revealed its recent petrological history. Multiple basalt types erupted at the summit in a time sequence. At least three different magma batches have been present beneath the Axial Summit caldera during the last millennium, each with a range in differentiation. The first, prior to 1100 CE, was compositionally diverse, dominantly aphyric T-MORB. The second, from ˜1220 to 1300 CE, was dominantly plagioclase-phyric, more mafic N-MORB erupted mostly in the central portion of the caldera. Since ˜1400 CE, lavas have been more differentiated, and nearly aphyric T-MORB mostly erupted in the caldera's rift zones. Parental magmas