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Sample records for acid igneous rocks

  1. 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.

  2. Ionium dating of igneous rocks.

    PubMed

    Kigoshi, K

    1967-05-19

    Local fractionation of uranium and thorium, between minerals within a sample of igneous rock at the time of crystallization, makes it possible to date its solidification by use of ionium and uranium. Results on samples of granite, pumice, and lava suggest that this method of dating is reliable.

  3. Mineral Detector for Igneous Rocks

    NASA Astrophysics Data System (ADS)

    Ishikawa, S. T.; Hart, S. D.; Gulick, V. C.

    2010-12-01

    We present a Raman spectral analysis tool that uses machine learning algorithms to classify pure minerals in igneous rocks. Experiments show greater than 90% accuracy classifying a test set of pure minerals against a database of similar reference minerals using an artificial neural network. Efforts are currently underway to improve this tool for use as a mineral detector in rock samples, an important milestone toward autonomously classifying rocks based on spectral, and previous imaging work. Although pure mineral classification has been widely successful, applying the same methods to rocks is difficult because the spectra may represent a combination of multiple, and often competing, mineral signatures. In such cases some minerals may appear with more intensity than others resulting in masking of weaker minerals. Furthermore, with our particular spectrometer (852 nm excitation, ~50 micron spot size), minerals such as potassium feldspar fluoresce, both obscuring its characteristic Raman features and suppressing those of weaker minerals. For example, plagioclase and quartz, two key minerals for determining the composition of igneous rocks, are often hidden by minerals such as potassium feldspar and pyroxene, and are consequently underrepresented in the spectral analysis. These technicalities tend to skew the perceived composition of a rock from its actual composition. Despite these obstacles, an experiment involving a training set of 26 minerals (plagioclase, potassium feldspar, pyroxene, olivine, quartz) and a test set of 57 igneous rocks (basalt, gabbro, andesite, diorite, dacite, granodiorite, rhyolite, granite) shows that generalizations derived from their spectral data are consistent with expected trends: as rock composition goes from felsic to mafic there is a marked increase in the detection of minerals such as plagioclase and pyroxene along with a decrease in the detection of minerals such as quartz and potassium feldspar. The results suggest that phaneritic

  4. Microscopic tubes in igneous rocks

    NASA Technical Reports Server (NTRS)

    Richter, D.; Simmons, G.

    1977-01-01

    Microscopic tubes have been observed in several igneous rocks and may be quite common. They occur in single crystals and have either elliptical or circular cross-sections 1 to 5 microns in diameter and are ten to hundreds of microns long. Microtubes may be hollow or partially or completely filled with another phase, but are distinct from acicular crystals of accessory minerals such as rutile. Microtubes can form by at least three processes: (1) the partial annealing of microcracks, (2) the natural etching of dislocations, or (3) the primary inclusion of fluid material during crystal growth.

  5. Kinetics of crystallization of igneous rocks

    SciTech Connect

    Kirkpatrick, R.J.

    1981-01-01

    The geochemistry of igneous rocks is discussed, with the primary objectives of bringing together the theories underlying the kinetics of crystallization of igneous rocks and illustrating the use of these theories in understanding experimental and observational data. The primary purpose of the chapter is to introduce current thinking about the kinetics of igneous rocks and to provide a basis for understanding other work. A basic assumption made in the discussion is that the rate of any chemical reaction, including the crystallization of igneous rocks, is zero at equilibrium and proceeds at a finite rate only at a finite deviation from equilibrium. As such, an understanding of the processes operating in igneous rocks requires an understanding of how deviation from equilibrium affects the rates and mechanisms of the processes occurring during crystallization. These processes are detailed, with special emphasis given to nucleation and crystal growth. (JMT)

  6. Spirit Discovers New Class of Igneous Rocks

    NASA Technical Reports Server (NTRS)

    2006-01-01

    During the past two-and-a-half years of traversing the central part of Gusev Crater, NASA's Mars Exploration Rover Spirit has analyzed the brushed and ground-into surfaces of multiple rocks using the alpha particle X-ray spectrometer, which measures the abundance of major chemical elements. In the process, Spirit has documented the first example of a particular kind of volcanic region on Mars known as an alkaline igneous province. The word alkaline refers to the abundance of sodium and potassium, two major rock-forming elements from the alkali metals on the left-hand side of the periodic table.

    All of the relatively unaltered rocks -- those least changed by wind, water, freezing, or other weathering agents -- examined by Spirit have been igneous, meaning that they crystallized from molten magmas. One way geologists classify igneous rocks is by looking at the amount of potassium and sodium relative to the amount of silica, the most abundant rock-forming mineral on Earth. In the case of volcanic rocks, the amount of silica present gives scientists clues to the kind of volcanism that occurred, while the amounts of potassium and sodium provide clues about the history of the rock. Rocks with more silica tend to erupt explosively. Higher contents of potassium and sodium, as seen in alkaline rocks like those at Gusev, may indicate partial melting of magma at higher pressure, that is, deeper in the Martian mantle. The abundance of potassium and sodium determines the kinds of minerals that make up igneous rocks. If igneous rocks have enough silica, potassium and sodium always bond with the silica to form certain minerals.

    The Gusev rocks define a new chemical category not previously seen on Mars, as shown in this diagram plotting alkalis versus silica, compiled by University of Tennessee geologist Harry McSween. The abbreviations 'Na2O' and 'K2O' refer to oxides of sodium and potassium. The abbreviation 'SiO2' refers to silica. The abbreviation 'wt

  7. Uranium in NIMROC standard igneous rock samples

    NASA Technical Reports Server (NTRS)

    Rowe, M. W.; Herndon, J. M.

    1976-01-01

    Results are reported for analysis of the uranium in multiple samples of each of six igneous-rock standards (dunite, granite, lujavrite, norite, pyroxenite, and syenite) prepared as geochemical reference standards for elemental and isotopic compositions. Powdered rock samples were examined by measuring delayed neutron emission after irradiation with a flux of the order of 10 to the 13th power neutrons/sq cm per sec in a nuclear reactor. The measurements are shown to compare quite favorably with previous uranium determinations for other standard rock samples.

  8. Igneous rocks from Apollo 16 rake samples

    NASA Technical Reports Server (NTRS)

    Dowty, E.; Keil, K.; Prinz, M.

    1974-01-01

    Results are reported for a study of seven holocrystalline feldspathic rocks (including a spinel troctolite and six melt rocks) and one mare basalt clast from the Apollo-16 rake samples. The composition and grain structure of each rock is described in detail. Only the spinel troctolite is considered a good candidate for a primary igneous cumulate formed during the original differentiation of the lunar crust. It is shown that the melt rocks probably resulted from shock melting followed by rapid crystallization of heterogeneous highland material and that compositional variations are probably due to mixing of various amounts of heterogeneous cumulates and KREEP components. It is suggested that the mare basalt clast may have been derived from Mare Fecunditatis, although the nearest mare to the Apollo-16 site is Nectaris.

  9. Acid neutralizing capacity and leachate results for igneous rocks, with associated carbon contents of derived soils, Animas River AML site, Silverton, Colorado

    USGS Publications Warehouse

    Yager, Douglas B.; Stanton, Mark R.; Choate, LaDonna M.; Burchell,

    2009-01-01

    Mine planning efforts have historically overlooked the possible acid neutralizing capacity (ANC) that local igneous rocks can provide to help neutralize acidmine drainage. As a result, limestone has been traditionally hauled to mine sites for use in neutralizing acid drainage. Local igneous rocks, when used as part of mine life-cycle planning and acid mitigation strategy, may reduce the need to transport limestone to mine sites because these rocks can contain acid neutralizing minerals. Igneous hydrothermal events often introduce moderately altered mineral assemblages peripheral to more intensely altered rocks that host metal-bearing veins and ore bodies. These less altered rocks can contain ANC minerals (calcite-chlorite-epidote) and are referred to as a propylitic assemblage. In addition, the carbon contents of soils in areas of new mining or those areas undergoing restoration have been historically unknown. Soil organic carbon is an important constituent to characterize as a soil recovery benchmark that can be referred to during mine cycle planning and restoration.
    This study addresses the mineralogy, ANC, and leachate chemistry of propylitic volcanic rocks that host polymetallic mineralization in the Animas River watershed near the historical Silverton, Colorado, mining area. Acid titration tests on volcanic rocks containing calcite (2 – 20 wt %) and chlorite (6 – 25 wt %), have ANC ranging from 4 – 146 kg/ton CaCO3 equivalence. Results from a 6-month duration, kinetic reaction vessel test containing layered pyritic mine waste and underlying ANC volcanic rock (saturated with deionized water) indicate that acid generating mine waste (pH 2.4) has not overwhelmed the ANC of propylitic volcanic rocks (pH 5.8). Sequential leachate laboratory experiments evaluated the concentration of metals liberated during leaching. Leachate concentrations of Cu-Zn-As-Pb for ANC volcanic rock are one-to-three orders of magnitude lower when compared to leached

  10. Introduction to the Apollo collections. Part 1: Lunar igneous rocks

    NASA Technical Reports Server (NTRS)

    Mcgee, P. E.; Warner, J. L.; Simonds, C. H.

    1977-01-01

    The basic petrographic, chemical, and age data is presented for a representative suite of igneous rocks gathered during the six Apollo missions. Tables are given for 69 samples: 32 igneous rocks and 37 impactites (breccias). A description is given of 26 basalts, four plutonic rocks, and two pyroclastic samples. The textural-mineralogic name assigned each sample is included.

  11. Charge Generation and Propagation in Igneous Rocks

    NASA Technical Reports Server (NTRS)

    Freund, Friedemann

    2000-01-01

    Resistivity changes, ground potentials, electromagnetic (EM) and luminous signals prior to or during earthquakes have been reported, in addition to ground uplift and tilt, and to changes in the seismic wave propagation parameters. However, no physical model exists that ties these diverse phenomena together. Through time-resolved impacts experiments it has been observed that, when igneous rocks (gabbro, diorite, granite) are impacted at low velocities (approx. 100 m/sec), highly mobile electronic charge carriers are generated, spreading from a small volume near the impact point, causing electric potentials, EM and light emission. The rock becomes momentarily conductive. When impacted at higher velocities (approx. 1.5 km/sec), the propagation of the P and S waves is registered through the transient piezoelectric response of quartz. At the same time, the rock volume is filled with mobile charge carriers, and a positive surface potential is registered. During the next 1-2 msec the surface potential oscillates, due to electron injection from ground. These observations are consistent with positive holes, e.g. defect electrons in the O(2-) sublattice, that can travel via the O 2p-dominated valence band of the silicate minerals at the speed of a phonon-mediated charge transfer. Before activation, the positive hole charge carriers lay dormant in form of positive hole pairs, PHP, electrically inactive, chemically equivalent to peroxy links in the structures of constituent minerals. PHPs are introduced by way of hydroxyl (O3Si-OH) incorporated into nominally anhydrous minerals when they crystallize in water-laden environments. Given that sound waves of even relatively low intensity appear to cause PHPs dissociation, thus generating mobile positive holes, it is proposed that microfracturing during rock deformation cause PHP dissociation. Depending on where and how much the rock volume is stressed, the positive holes are expected to form fluctuating charge clouds in the

  12. On the weathering of Martian igneous rocks

    NASA Technical Reports Server (NTRS)

    Dreibus, G.; Waenke, H.

    1992-01-01

    Besides the young crystallization age, one of the first arguments for the martian origin of shergottite, nakhlite, and chassignite (SNC) meteorites came from the chemical similarity of the meteorite Shergotty and the martian soil as measured by Viking XRF analyses. In the meantime, the discovery of trapped rare gas and nitrogen components with element and isotope ratios closely matching the highly characteristic ratios of the Mars atmosphere in the shock glasses of shergottite EETA79001 was further striking evidence that the SNC's are martian surface rocks. The martian soil composition as derived from the Viking mission, with its extremely high S and Cl concentrations, was interpreted as weathering products of mafic igneous rocks. The low SiO2 content and the low abundance of K and other trace elements in the martian soils point to a mafic crust with a considerably smaller degree of fractionation compared to the terrestrial crust. However, the chemical evolution of the martian regolith and soil in respect to surface reaction with the planetary atmosphere or hydrosphere is poorly understood. A critical point in this respect is that the geochemical evidence as derived from the SNC meteorites suggests that Mars is a very dry planet that should have lost almost all its initially large water inventory during its accretion.

  13. High crystallization temperatures indicated for igneous rocks from tranquillity base.

    PubMed

    Skinner, B J

    1970-01-30

    Complex intergrowths of troilite (FeS) and iron in the igneous rocks from Tranquillity Base contain 8.4 percent native iron by volume. The intergrowths were derived from an initially homogeneous sulfide liquid that separated immiscibly from the magma at 1140 degrees C or above. Textures show that the sulfide liquid formed late in the crystallization and cooling history of the igneous rocks and after the major ilmenite and pyroxene had formed.

  14. Sudbury Igneous Complex: Impact melt or igneous rock? Implications for lunar magmatism

    NASA Technical Reports Server (NTRS)

    Norman, Marc D.

    1992-01-01

    The recent suggestion that the Sudbury Igneous Complex (SIC) is a fractionated impact melt may have profound implications for understanding the lunar crust and the magmatic history of the Moon. A cornerstone of much current thought on the Moon is that the development of the lunar crust can be traced through the lineage of 'pristine' igneous rocks. However, if rocks closely resembling those from layered igneous intrusions can be produced by differentiation of a large impact melt sheet, then much of what is thought to be known about the Moon may be called into question. This paper presents a brief evaluation of the SIC as a differentiated impact melt vs. endogenous igneous magma and possible implications for the magmatic history of the lunar crust.

  15. 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.

  16. Towards a comprehensive classification of igneous rocks and magmas

    NASA Astrophysics Data System (ADS)

    Middlemost, Eric A. K.

    1991-08-01

    The IUGS Subcommission on the Systematics of Igneous Rocks has recently published an excellent book on the classification of these rocks. This event has shifted the vexed question of classification towards the top of the agenda in igneous petrology. Over the years the Subcommission has used many different criteria to establish the positions of the boundaries between the various common igneous rocks. It now has to adopt a holistic approach and develop a comprehensive, coherent classification that is purged of all the minor anomalies that arise between the various classifications that it has approved. It is appreciated that the Subcommission's classification was never intended to have any genetic implications; however, it is suggested that an ideal classification should he presented in such a way that it is able to group rocks into an order that directs attention to petrogenetic relationships between individual rocks and larger groups of rocks. Unfortunately, many of the Subcommission's definitions are Earth chauvinistic; for example, igneous rocks are defined as being those rocks that solidified from a molten state either within or on the surface of the Earth. Nowhere in the book is it acknowledged that during the past 20 years, while the Subcommission has been framing its many recommendations, a whole new science of planetary petrology has subsumed classical petrology. In any new edition of the book, the Subcommission should acknowledge that rocks are essentially the solid materials of which planets, natural satellites and other broadly similar cosmic bodies are made. The Subcommission should also explicitly recognise that igneous rocks can be divided into either a main sequence of essentially common rocks or a number of supplementary clans of special rocks that evolved outside the main sequence. It is hoped that in the near future the Subcommission will rescind its recommendation that the TAS classification should be regarded as an adjunct to its more traditional

  17. Net Acid Production, Acid Neutralizing Capacity, and Associated Mineralogical and Geochemical Characteristics of Animas River Watershed Igneous Rocks Near Silverton, Colorado

    USGS Publications Warehouse

    Yager, Douglas B.; Choate, LaDonna; Stanton, Mark R.

    2008-01-01

    This report presents results from laboratory and field studies involving the net acid production (NAP), acid neutralizing capacity (ANC), and magnetic mineralogy of 27 samples collected in altered volcanic terrain in the upper Animas River watershed near Silverton, Colo., during the summer of 2005. Sampling focused mainly on the volumetrically important, Tertiary-age volcanic and plutonic rocks that host base- and precious-metal mineralization in the study area. These rocks were analyzed to determine their potential for neutralization of acid-rock drainage. Rocks in the study area have been subjected to a regional propylitic alteration event, which introduced calcite, chlorite (clinochlore), and epidote that have varying amounts and rates of acid neutralizing capacity (ANC). Locally, hydrothermal alteration has consumed any ANC and introduced minerals, mainly pyrite, that have a high net acid production (NAP). Laboratory studies included hydrogen pyroxide (H2O2) acid digestion and subsequent sodium hydroxide (NaOH) titration to determine NAP, and sulfuric acid (H2SO4) acid titration experiments to determine ANC. In addition to these environmental rock-property determinations, mineralogical, chemical, and petrographic characteristics of each sample were determined through semiquantitative X-ray diffractometry (Rietveld method), optical mineralogy, wavelength dispersive X-ray fluorescence, total carbon-carbonate, and inductively coupled plasma?mass spectrometric analysis. An ANC ranking was assigned to rock samples based on calculated ANC quantity in kilograms/ton (kg/t) calcium carbonate equivalent and ratios of ANC to NAP. Results show that talus near the southeast Silverton caldera margin, composed of andesite clasts of the Burns Member of the Silverton Volcanics, has the highest ANC (>100 kg/t calcium carbonate equivalent) with little to no NAP. The other units found to have moderate to high ANC include (a) andesite lavas and volcaniclastic rocks of the San Juan

  18. Uranium and other element analyses of igneous rocks of Arkansas

    SciTech Connect

    Steele, K.F.

    1982-05-01

    Seventy-six samples of igneous rocks representing a variety of rock types and locations in Arkansas were analyzed by neutron activation analysis for the elements U, Th, Na, Al, Sc, Ti, V, Mn, Fe, La, Ce, Sm, Eu, Dy, Yb, Lu, and Hf. Samples were collected from the major igneous intrusions at Granite Mountain, Bauxite, Magnet Cove, Potash Sulfur Springs, and Murfreesboro, representing various syenites, lamprophyres, carbonatite, kimberlite, and periodotite. To make the data available for public use without further delay, this report is being issued without the normal technical and copy editing.

  19. Winter Ice and Snow as Models of Igneous Rock Formation.

    ERIC Educational Resources Information Center

    Romey, William D.

    1983-01-01

    Examines some features of ice and snow that offer teachers and researchers help in understanding many aspects of igneous processes and configurations. Careful observation of such processes as melting, decay, evolution, and snow accumulation provide important clues to understanding processes by which many kinds of rocks form. (Author/JN)

  20. Log evaluation of oil-bearing igneous rocks

    SciTech Connect

    Khatchikian, A.

    1983-12-01

    The evaluation of porosity, water saturation and clay content of oilbearing igneous rocks with well logs is difficult due to the mineralogical complexity of this type of rocks. The log responses to rhyolite and rhyolite tuff; andesite, dacite and zeolite tuff; diabase and basalt have been studied from examples in western Argentina and compared with values observed in other countries. Several field examples show how these log responses can be used in a complex lithology program to make a complete evaluation.

  1. Lunar igneous rocks and the nature of the lunar interior

    NASA Technical Reports Server (NTRS)

    Hays, J. F.; Walker, D.

    1974-01-01

    Lunar igneous rocks are interpreted, which can give useful information about mineral assemblages and mineral chemistry as a function of depth in the lunar interior. Terra rocks, though intensely brecciated, reveal, in their chemistry, evidence for a magmatic history. Partial melting of feldspathic lunar crustal material occurred in the interval 4.6 to 3.9 gy. Melting of ilmenite-bearing cumulates at depths near 100 km produced parent magmas for Apollo 11 and 17 titaniferous mare basalts in the interval 3.8 to 3.6 gy. Melting of ilmenite-free olivine pyroxenites at depths greater than 200 km produced low-titanium mare basalts in the interval 3.4 to 3.1 gy. No younger igneous rocks have yet been recognized among the lunar samples and present-day melting seems to be limited to depths greater than 1000 km.

  2. Lunar igneous rocks and the nature of the lunar interior

    NASA Technical Reports Server (NTRS)

    Hays, J. F.; Walker, D.

    1977-01-01

    Lunar igneous rocks, properly interpreted, can give useful information about mineral assemblages and mineral chemistry as a function of depth in the lunar interior. Though intensely brecciated, terra rocks reveal, in their chemistry, evidence for a magmatic history. Partial melting of feldspathic lunar crustal material occurred in the interval 4.6 to 3.9 Gy. Melting of ilmenite-bearing cumulates at depths near 100 km produced parent magmas for Apollo 11 and 17 titaniferous mare basalts in the interval 3.8 to 3.6 Gy. Melting of ilmenite-free olivine pyroxenites (also cumulates?) at depths greater than 200 km produced low-titanium mare basalts in the interval 3.4 to 3.1 Gy. No younger igneous rocks have yet been recognized among the lunar samples and present-day melting seems to be limited to depths greater than 1000 km.

  3. Magnetostriction and palæomagnetism of igneous rocks

    USGS Publications Warehouse

    Graham, John W.; Buddington, A.F.; Balsley, James R.

    1959-01-01

    IN a recent communication, Stott and Stacey1 report on a “crucial experiment” from which they conclude: “This excellent agreement between the dip and the directions of artificial thermoremanent magnetization of the stressed and unstressed rocks indicates that large systematic errors due to magnetostriction are most improbable in igneous rocks of types normally used for palæomagnetic work”. This experiment was intended to test the proposals2 and measurements3 bearing on the role of magnetostriction in rock magnetism. We present here our reasons for believing that the experiment was not crucial and that the conclusion is not justified.

  4. Charge Generation and Propagation in Igneous Rocks

    NASA Technical Reports Server (NTRS)

    Freund, Friedemann

    2002-01-01

    Various electrical phenomena have been reported prior to or concurrent with earthquakes such as resistivity changes, ground potentials, electromagnetic (EM), and luminous signals. Doubts have been raised as to whether some of these phenomena are real and indeed precursory. One of the reasons for uncertainty is that, despite decades of intense work, there is still no physically coherent model. Using low- to medium-velocity impacts to measure electrical signals with microsecond time resolution, it has now been observed that when dry gabbro and diorite cores are impacted at relatively low velocities, approximately 100 m/s, highly mobile charge carriers are generated in a small volume near the impact point. They spread through the rocks, causing electric potentials exceeding +400 mV, EM, and light emission. As the charge cloud spreads, the rock becomes momentarily conductive. When a dry granite block is impacted at higher velocity, approximately 1.5 km/s, the propagation of the P and S waves is registered through the transient piezoelectric response of quartz. After the sound waves have passed, the surface of the granite block becomes positively charged, suggesting the same charge carriers as observed during the low-velocity impact experiments, expanding from within the bulk. During the next 2-3 ms the surface potential oscillates, indicating pulses of electrons injected from ground and contact electrodes. The observations are consistent with positive holes, e.g., defect electrons in the O(2-) sublattice, traveling via the O 2p-dominated valence band of the silicate minerals. Before activation, the positive holes lay dormant in the form of electrically inactive positive hole pairs (PHP), chemically equivalent to peroxy links, O3X/OO\\XO3, with X=Si(4+), Al(3+), etc. PHPs are introduced into the minerals by way of hydroxyl,O3X-OH, which all nominally anhydrous minerals incorporate when crystallizing in H2O-laden environments. The fact that positive holes can be

  5. Igneous Rocks of the Indian Ocean Floor.

    PubMed

    Engel, C G; Fischer, R L; Engel, A E

    1965-10-29

    Four dredge hauls from near the crest and from the eastern flank of the seismically active Mid-Indian Ocean Ridge at 23 degrees to 24 degrees S, at depths of 3700 to 4300 meters, produced only low-potassium tholeiitic basalt similar in chemical and mineralogic composition to basalts characteristic of ridges and rises in the Atlantic and Pacific oceans. A fifth haul, from a depth of 4000 meters on the lower flank of a seamount on the ocean side of the Indonesian Trench, recovered tholeiitic basalt with higher concentrations of K and Ti and slightly lower amounts of Si and Ca than the typical-oceanic tholeiite of the ridge. The last sample is vesicular, suggesting depression of the area since the basalt was emplaced. Many of the rocks dredged are variously decomposed and hydrated, but there is no evidence of important chemical modification toward conversion of the lava flows to spilite during extrusion or solidification.

  6. Igneous rocks of the Indian ocean floor

    USGS Publications Warehouse

    Engel, C.G.; Fischer, R.L.; Engel, A.E.J.

    1965-01-01

    Four dredge hauls from near the crest and from the eastern flank of the seismically active Mid-Indian Ocean Ridge at 23?? to 24??S, at depths of 3700 to 4300 meters, produced only low-potassium tholeiitic basalt similar in chemical and mineralogic composition to basalts characteristic of ridges and rises in the Atlantic and Pacific oceansA fifth haul, from a depth of 4000 meters on the lower flank of a seamount on the ocean side of the Indonesian Trench, recovered tholeiitic basalt with higher concentrations of K and Ti and slightly lower amounts of Si and Ca than the typical oceanic tholeiite of the ridgeThe last sample is vesicular, suggesting depression of the area since the basalt was emplacedMany of the rocks dredged are variously decomposed and hydrated, but there is no evidence of important chemical modification toward conversion of the lava flows to spilite during extrusion or solidification.

  7. Igneous rocks of the East Pacific Rise

    USGS Publications Warehouse

    Engel, A.E.J.; Engel, C.G.

    1964-01-01

    The apical parts of large volcanoes along the East Pacific Rise (islands and seamounts) are encrusted with rocks of the alkali volcanic suite (alkali basalt, andesine- and oligoclase-andesite, and trachyte). In contrast, the more submerged parts of the Rise are largely composed of a tholeiitic basalt which has low concentrations of K, P, U, Th, Pb, and Ti. This tholeiitic basalt is either the predominant or the only magma generated in the earth's mantle under oceanic ridges and rises. It is at least 1000-fold more abundant than the alkali suite, which is probably derived from tholeiitic basalt by magmatic differentiation in and immediately below the larger volcanoes. Distinction of oceanic tholeiites from almost all continental tholeiites is possible on the simple basis of total potassium content, with the discontinuity at 0.3 to 0.5 percent K2O by weight. Oceanic tholeiites also are readily distinguished from some 19 out of 20 basalts of oceanic islands and seamount cappings by having less than 0.3 percent K2O by weight and more than 48 percent SiO2. Deep drilling into oceanic volcanoes should, however, core basalts transitional between the oceanic tholeiites and the presumed derivative alkali basalts.The composition of the oceanic tholeiites suggests that the mantle under the East Pacific Rise contains less than 0.10 percent potassium oxide by weight; 0.1 part per million of uranium and 0.4 part of thorium; a potassium:rubidium ratio of about 1200 and a potassium: uranium ratio of about 104.

  8. Determination of ultra-micro amounts of sulfur in igneous rocks by spectrofluorimetry using 2-(o-hydroxyphenyl) benzoxazole derivatization and tin(II)-strong phosphoric acid-assisted reduction.

    PubMed

    Hong, Y D; Namgung, S W; Yoshida, M; Malik, A

    2000-02-07

    A new and very sensitive method was developed for the determination of ultra-micro amounts of sulfur in igneous rock samples. The sulfur compounds in an igneous rock sample are reduced and released in the form of hydrogen sulfide by heating with a tin(II)-strong phosphoric acid (SPA) reagent. The liberated hydrogen sulfide is carried by a flow of nitrogen into a copper(II) absorbing solution to obtain a precipitate of copper(II) sulfide. The remaining copper(II) ion forms a chelate with 2-(o-hydroxyphenyl)benzoxazole (HPB) and quenches the fluorescence of HPB. The amount of sulfide is determined by measuring the HPB fluorescence intensity. The optimum reaction conditions were stoichiometrically investigated. By the present method using 0.1-0.2 g of rock sample, ultramicro amounts of sulfur (0.1-12.8 mug) could be quantitatively separated, collected, and determined with a relative standard deviation of 1.37% for a sample containing 5.7 mug of sulfur (95% confidence level).

  9. Mafic and felsic igneous rocks at Gale crater

    NASA Astrophysics Data System (ADS)

    Sautter, Violaine; Cousin, Agnès; Mangold, Nicolas; Toplis, Michael; Fabre, Cécile; Forni, Olivier; Payré, Valérie; Gasnault, Olivier; Ollila, Anne; Rapin, William; Fisk, Martin; Meslin, Pierre-Yves; Wiens, Roger; Maurice, Sylvestre; Lasue, Jérémie; Newsom, Horton; Lanza, Nina

    2015-04-01

    The Curiosity rover landed at Gale, an early Hesperian age crater formed within Noachian terrains on Mars. The rover encountered a great variety of igneous rocks to the west of the Yellow Knife Bay sedimentary unit (from sol 13 to 800) which are float rocks or clasts in conglomerates. Textural and compositional analyses using MastCam and ChemCam Remote micro Imager (RMI) and Laser Induced Breakdown Spectroscopy (LIBS) with a ˜300-500 µm laser spot lead to the recognition of 53 massive (non layered) igneous targets, both intrusive and effusive, ranging from mafic rocks where feldspars form less than 50% of the rock to felsic samples where feldspar is the dominant mineral. From morphology, color, grain size, patina and chemistry, at least 5 different groups of rocks have been identified: (1) a basaltic class with shiny aspect, conchoidal frature, no visible grains (less than 0.2mm) in a dark matrix with a few mm sized light-toned crystals (21 targets) (2) a porphyritic trachyandesite class with light-toned, bladed and polygonal crystals 1-20 mm in length set in a dark gray mesostasis (11 targets); (3) light toned trachytes with no visible grains sometimes vesiculated or forming flat targets (6 targets); (4) microgabbro-norite (grain size < 1mm) and gabbro-norite (grain size >1 mm) showing dark and light toned crystals in similar proportion ( 8 targets); (5) light-toned diorite/granodiorite showing coarse granular (>4 mm) texture either pristine or blocky, strongly weathered rocks (9 rock targets). Overall, these rocks comprise 2 distinct geochemical series: (i) an alkali-suite: basanite, gabbro trachy-andesite and trachyte) including porphyritic and aphyric members; (ii) quartz-normative intrusives close to granodioritic composition. The former looks like felsic clasts recently described in two SNC meteorites (NWA 7034 and 7533), the first Noachian breccia sampling the martian regolith. It is geochemically consistent with differentiation of liquids produced by low

  10. Natural radioactivity and radon exhalation rate in Brazilian igneous rocks.

    PubMed

    Moura, C L; Artur, A C; Bonotto, D M; Guedes, S; Martinelli, C D

    2011-07-01

    This paper reports the natural radioactivity of Brazilian igneous rocks that are used as dimension stones, following the trend of other studies on the evaluation of the risks to the human health caused by the rocks radioactivity as a consequence of their use as cover indoors. Gamma-ray spectrometry has been utilized to determine the (40)K, (226)Ra and (232)Th activity concentrations in 14 rock types collected at different quarries. The following activity concentration range was found: 12.18-251.90 Bq/kg for (226)Ra, 9.55-347.47 Bq/kg for (232)Th and 407.5-1615.0 Bq/kg for (40)K. Such data were used to estimate Ra(eq), H(ex) and I(γ), which were compared with the threshold limit values recommended in literature. They have been exceeded for Ra(eq) and H(ex) in five samples, where the highest indices corresponded to a rock that suffered a process of ductile-brittle deformation that caused it a microbrecciated shape. The exhalation rate of Rn and daughters has also been determined in slabs consisting of rock pieces ~10 cm-long, 5 cm-wide and 3 cm-thick. It ranged from 0.24 to 3.93 Bq/m(2)/h and exhibited significant correlation with eU (=(226)Ra), as expected. The results indicated that most of the studied rocks did not present risk to human health and may be used indoors, even with low ventilation. On the other hand, igneous rocks that yielded indices above the threshold limit values recommended in literature may be used outdoors without any restriction or indoors with ample ventilation.

  11. Effects of Compositional and Structural Variations on Log Responses in Igneous and Metamorphic Rocks

    NASA Astrophysics Data System (ADS)

    Pechnig, R.; Bartetzko, A.; Delius, H.

    2001-12-01

    Petrophysical in-situ data of several boreholes drilled igneous and metamorphic rocks of continental and oceanic basement were analyzed in order to characterize and classify the occurring rock types. Since physical properties of crystalline rocks are controlled by both, compositional and structural features, one objective of this study was to develop methods to detect and quantify matrix effects. The comparison of mineralogical and geochemical core data with wireline data reveal following systematic observations: (1) Mafic rocks (e.g. oceanic basalts, volcanic island basalts, gabbros and amphibolites) generally have low contents of radioactive minerals. This is in particular valid for mafic rocks from the upper and lower oceanic crust. Slight increases in gamma-ray are related to an enrichment in potassium due to seafloor alteration. In contrast to this uniform, mantle source controlled rocks, extrusives and re-sedimented material from ocean islands and large igneous provinces show a large scatter in gamma-ray responses as a result of their more complex evolution. Mafic rocks recovered from boreholes into continental crust, are characterized by high gamma-ray values, due to enrichment of thorium and uranium during regional metamorphism. In contrast to the mafic plutonic and metamorphic rocks, where the density and p-wave velocity is controlled by the mineralogical composition, the physical parameters of mafic volcanic rocks are strongly affected by fracturing and vesicularity. Density, p-wave velocity and electrical resistivity logs are significantly lowered depending on the degree of vesicularity and fracturing. (2) Acid to intermediate igneous rocks and orthogneisses are distinguishable from paragneisses by their log responses despite showing a similar geochemical composition. The main difference occurs for the relation of the gamma-ray log to the density and neutron porosity log. The gamma-ray in paragneisses is controlled by the amount of phyllosilicates, which

  12. Igneous rocks of the West Sakhalin Terrane of Sakhalin Island

    NASA Astrophysics Data System (ADS)

    Grannik, V. M.

    2016-10-01

    It has been determined that the Rozhdestvenka Formation of the West Sakhalin Terrane composed of Late Mesozoic igneous rocks is a fragment of the accretionary prism of the Rebun-Kabato-Moneron-Samarga island-arc system. Volcanic eruptions, as well as destruction of the Rebun-Kabato-Moneron-Samarga island-arc and the East Sikhote-Alin volcano plutonic marginal continental belt, were the sources of pyroclastic and clastic material entering the sedimentary basin, where the Pobedinsk and Krasnoyarka suites of the West Sakhalin Terrane were formed.

  13. Evolution of the martian mantle as recorded by igneous rocks

    NASA Astrophysics Data System (ADS)

    Balta, J. B.; McSween, H. Y.

    2013-12-01

    Martian igneous rocks provide our best window into the current state of the martian mantle and its evolution after accretion and differentiation. Currently, those rocks have been examined in situ by rovers, characterized in general from orbiting spacecraft, and analyzed in terrestrial laboratories when found as meteorites. However, these data have the potential to bias our understanding of martian magmatism, as most of the available meteorites and rover-analyzed rocks come from the Amazonian (<2 Ga) and Hesperian (~3.65 Ga) periods respectively, while igneous rocks from the Noachian (>3.8 Ga) have only been examined by orbiters and as the unique meteorite ALH 84001. After initial differentiation, the main planetary-scale changes in the structure of Mars which impact igneous compositions are cooling of the planet and thickening of the crust with time. As the shergottite meteorites give ages <500 Ma1, they might be expected to represent thick-crust, recent volcanism. Using spacecraft measurements of volcanic compositions and whole rock compositions of meteorites, we demonstrate that the shergottite meteorites do not match the composition of the igneous rocks composing the young volcanoes on Mars, particularly in their silica content, and no crystallization or crustal contamination trend reproduces the volcanoes from a shergottite-like parent magma. However, we show that the shergottite magmas do resemble older martian rocks in composition and mineralogy. The Noachian-aged meteorite ALH 84001 has similar radiogenic-element signatures to the shergottites and may derive from a similar mantle source despite the age difference2. Thus, shergottite-like magmas may represent melting of mantle sources that were much more abundant early in martian history. We propose that the shergottites represent the melting products of an originally-hydrous martian mantle, containing at least several hundred ppm H2O. Dissolved water can increase the silica content of magmas and thus

  14. Thermal diffusivity of igneous rocks at elevated pressure and temperature

    SciTech Connect

    Durham, W.B.; Mirkovich, V.V.; Heard, H.C.

    1987-10-10

    Thermal diffusivity measurements of seven igneous rocks were made to temperatures of 400 /sup 0/C and pressures of 200 MPa. The measuring method was based on the concept of cylindrical symmetry and periodic heat pulses. The seven rocks measured were Westerly (Rhode Island) granite, Climax Stock (Nevada) quartz monzonite, Pomona (Washington) basalt, Atikokan (Ontario, Canada) granite, Creighton (Ontario, Canada) gabbro, East Bull Lake (Ontario, Canada) gabbro, and Stripa (Sweden) granite. The diffusivity of all the rocks showed a positive linear dependence on inverse temperature and, excluding the East Bull Lake gabbro, showed a linear dependence on quartz content. (Quartz content varied from 0 to 31% by volume.) Diffusivity in all cases rose or remained steady with increasing confining pressure. The pressure effect was strongest at lowest pressures and vanished by levels between 10 and 100 MPa, depending on rock type. The pressure effect (measured as a percentage change in diffusivity) is stronger in the four rocks of granite composition than in the three of basaltic composition. Our results agree well with existing thermal diffusivity measurements at atmospheric pressure.

  15. Geochemical and modal data for igneous rocks associated with epithermal mineral deposits

    USGS Publications Warehouse

    du Bray, Edward A.

    2014-01-01

    The purposes of this report are to (1) present available geochemical and modal data for igneous rocks associated with epithermal mineral deposits and (2) to make those data widely and readily available for subsequent, more in-depth consideration and interpretation. Epithermal precious and base-metal deposits are commonly associated with subduction-related calc-alkaline to alkaline arc magmatism as well as back-arc continental rift magmatism. These deposits form in association with compositionally diverse extrusive and intrusive igneous rocks. Temperature and depth regimes prevailing during deposit formation are highly variable. The deposits form from hydrothermal fluids that range from acidic to near-neutral pH, and they occur in a variety of structural settings. The disparate temperature, pressure, fluid chemistry, and structural controls have resulted in deposits with wide ranging characteristics. Economic geologists have employed these characteristics to develop classification schemes for epithermal deposits and to constrain the important genetic processes responsible for their formation.

  16. Thermal conductivity anisotropy of metasedimentary and igneous rocks

    NASA Astrophysics Data System (ADS)

    Davis, Michael G.; Chapman, David S.; van Wagoner, Thomas M.; Armstrong, Phillip A.

    2007-05-01

    Thermal conductivity anisotropy was determined for three sets of metasedimentary and igneous rocks from central Utah, USA. Most conductivity measurements were made in transient mode with a half-space, line source instrument oriented in two orthogonal directions on a flat face cut perpendicular to bedding. One orientation of the probe yields thermal conductivity parallel to bedding (kpar) directly, the other orientation of the probe measures a product of conductivities parallel and perpendicular to bedding from which the perpendicular conductivity (kperp) is calculated. Some direct measurements of kpar and kperp were made on oriented cylindrical discs using a conventional divided bar device in steady state mode. Anisotropy is defined as kpar/kperp. Precambrian argillites from Big Cottonwood Canyon have anisotropy values from 0.8 to 2.1 with corresponding conductivity perpendicular to bedding of 2.0 to 6.2 W m-1 K-1. Anisotropy values for Price Canyon sedimentary samples are less than 1.2 with a mean of 1.04 although thermal conductivity perpendicular to bedding for the samples varied from 1.3 to 5.0 W m-1 K-1. The granitic rocks were found to be essentially isotropic with thermal conductivity perpendicular to bedding having a range of 2.2 to 3.2 W m-1 K-1 and a mean of 2.68 W m-1 K-1. The results confirm the observation by Deming [1994] that anisotropy is negligible for rocks having kperp greater than 4.0 W m-1 K-1 and generally increases for low conductivity metamorphic and clay-rich rocks. There is little evidence, however, for his suggestion that thermal conductivity anisotropy of all rocks increases systematically to about 2.5 for low thermal conductivity rocks.

  17. Complete Analytical Data for Samples of Jurassic Igneous Rocks in the Bald Mountain Mining District, Nevada

    USGS Publications Warehouse

    du Bray, Edward A.

    2009-01-01

    This report presents all petrographic, major oxide, and trace element data for a set of 109 samples collected during an investigation of Jurassic igneous rocks in the Bald Mountain mining district, Nevada. Igneous rocks in the district include the Bald Mountain stock, quartz-feldspar porphyry dikes, basaltic andesite dikes, aplite sills, and rare lamprophyre dikes. These rocks, although variably altered near intrusion-related mineral deposits, are fresh in many parts of the district. Igneous rocks in the district are hosted by Paleozoic sedimentary rocks.

  18. The "Key" Method of Identifying Igneous and Metamorphic Rocks in Introductory Laboratory.

    ERIC Educational Resources Information Center

    Eves, Robert Leo; Davis, Larry Eugene

    1987-01-01

    Proposes that identification keys provide an orderly strategy for the identification of igneous and metamorphic rocks in an introductory geology course. Explains the format employed in the system and includes the actual key guides for both igneous and metamorphic rocks. (ML)

  19. Presentation and interpretation of chemical data for igneous rocks

    USGS Publications Warehouse

    Wright, T.L.

    1974-01-01

    Arguments are made in favor of using variation diagrams to plot analyses of igneous rocks and their derivatives and modeling differentiation processes by least-squares mixing procedures. These methods permit study of magmatic differentiation and related processes in terms of all of the chemical data available. Data are presented as they are reported by the chemist and specific processes may be modeled and either quantitatively described or rejected as inappropriate or too simple. Examples are given of the differing interpretations that can arise when data are plotted on an AEM ternary vs. the same data on a full set of MgO variation diagrams. Mixing procedures are illustrated with reference to basaltic lavas from the Columbia Plateau. ?? 1974 Springer-Verlag.

  20. Primary igneous rocks on Mars: Composition and distribution

    NASA Technical Reports Server (NTRS)

    Singer, Robert B.; Mcsween, Harry Y., Jr.

    1991-01-01

    The present knowledge of the crustal composition of Mars is synthesized and implications discussed for in-situ resource utilization. Sources of information include remote sensing observations, Viking XRF chemical measurements, and characteristics of the SNC meteorites (which most researchers now believe originated on Mars). There are a number of lines of evidence that abundant ferrous-iron rich igneous crustal rocks (and derivative soils) are available at or very near the current Martian surface at many locations on the planet. Most of these exposures show spectroscopic evidence for abundant pyroxene, consistent with basaltic compositions. The SNC meteorites, which have basaltic compositions, were also studied extensively. Interpretations of Mars crustal chemistry and mineralogy (petrology) based on these various sources are reviewed, and their consistencies and differences are discussed.

  1. Major and trace elements in igneous rocks from Apollo 15.

    NASA Technical Reports Server (NTRS)

    Helmke, P. A.; Blanchard, D. P.; Haskin, L. A.; Telander, K.; Weiss, C.; Jacobs, J. W.

    1973-01-01

    The concentrations of major and trace elements have been determined in igneous rocks from Apollo 15. All materials analyzed have typical depletions of Eu except for minerals separated from sample 15085. Four samples have concentrations of trace elements that are similar to those of KREEP. The samples of mare basalt from Apollo 15 have higher concentrations of FeO, MgO, Mn, and Cr and lower concentrations of CaO, Na2O, K2O, and rare-earth elements (REE) as compared to the samples of mare basalt from Apollos 11, 12, and 14. The samples can be divided into two groups on the basis of their normative compositions. One group is quartz normative and has low concentrations of FeO while the other is olivine normative and has high concentrations of FeO. The trace element data indicate that the samples of olivine normative basalt could be from different portions of a single lava flow.

  2. Integrating isotopic fingerprinting with petrology: how do igneous rocks evolve?

    NASA Astrophysics Data System (ADS)

    Davidson, J. P.

    2002-12-01

    In the title of his seminal work, N.L. Bowen recognized the fundamental importance of magmatic evolution in producing the spectrum of igneous rocks. Indeed it is difficult to imagine a hot highly reactive fluid passing through c. 100 km of a chemically distinct medium (lithosphere) without evolving through cooling, crystallization and interaction with the wall rocks. The fact that magmas evolve - almost invariably through open system processes - has been largely marginalized in the past 30 years by the desire to use them as probes of mantle source regions. This perspective has been driven principally by advances offered by isotope geochemistry, through which components and sources can be effectively fingerprinted. Two fundamental observations urge caution in ignoring differentiation effects; 1) the scarcity of truly primary magmas according to geochemical criteria (recognized long ago by petrologists), and 2) the common occurrence of petrographic criteria attesting to open system evolution. Recent advances in multicollector mass spectrometry permit integration of the powerful diagnostic tools of isotope geochemistry with petrographic observations through accurate and precise analysis of small samples. Laser ablation and microdrilling enable sampling within and between mineral phases. The results of our microsampling investigations give widespread support for open system evolution of magmas, and provide insights into the mechanisms and timescales over which this occurs. For example; 1) core-rim decreases in 87Sr/86Sr in zoned plagioclase crystals from 1982 lavas of El Chichon volcano, Mexico, argue that the zoning and isotopic changes are in response to magma recharge mixing with an originally contaminated resident magma; 2) Single grain and intra-grain isotopic analyses of mineral phases from Ngauruhoe andesites (New Zealand) are highly variable, arguing that bulk rock data reflect mechanical aggregations of components which have evolved in discrete domains of the

  3. Geochemical characteristics of igneous rocks associated with epithermal mineral deposits—A review

    USGS Publications Warehouse

    du Bray, Edward A.

    2017-01-01

    Newly synthesized data indicate that the geochemistry of igneous rocks associated with epithermal mineral deposits varies extensively and continuously from subalkaline basaltic to rhyolitic compositions. Trace element and isotopic data for these rocks are consistent with subduction-related magmatism and suggest that the primary source magmas were generated by partial melting of the mantle-wedge above subducting oceanic slabs. Broad geochemical and petrographic diversity of individual igneous rock units associated with epithermal deposits indicate that the associated magmas evolved by open-system processes. Following migration to shallow crustal reservoirs, these magmas evolved by assimilation, recharge, and partial homogenization; these processes contribute to arc magmatism worldwide.Although epithermal deposits with the largest Au and Ag production are associated with felsic to intermediate composition igneous rocks, demonstrable relationships between magmas having any particular composition and epithermal deposit genesis are completely absent because the composition of igneous rock units associated with epithermal deposits ranges from basalt to rhyolite. Consequently, igneous rock compositions do not constitute effective exploration criteria with respect to identification of terranes prospective for epithermal deposit formation. However, the close spatial and temporal association of igneous rocks and epithermal deposits does suggest a mutual genetic relationship. Igneous systems likely contribute heat and some of the fluids and metals involved in epithermal deposit formation. Accordingly, deposit formation requires optimization of source metal contents, appropriate fluid compositions and characteristics, structural features conducive to hydrothermal fluid flow and confinement, and receptive host rocks, but not magmas with special compositional characteristics.

  4. The nakhlite meteorites: Augite-rich igneous rocks from Mars

    NASA Technical Reports Server (NTRS)

    Treiman, Allan H.

    2005-01-01

    The seven nakhlite meteorites are augite-rich igneous rocks that formed in flows or shallow intrusions of basaltic magma on Mars. They consist of euhedral to subhedral crystals of augite and olivine (to 1 cm long) in fine-grained mesostases. The augite crystals have homogeneous cores of Mg' = 63% and rims that are normally zoned to iron enrichment. The core-rim zoning is cut by iron-enriched zones along fractures and is replaced locally by ferroan low-Ca pyroxene. The core compositions of the olivines vary inversely with the steepness of their rim zoning - sharp rim zoning goes with the most magnesian cores (Mg' = 42%), homogeneous olivines are the most ferroan. The olivine and augite crystals contain multiphase inclusions representing trapped magma. Among the olivine and augite crystals is mesostasis, composed principally of plagioclase and/or glass, with euhedra of titanomagnetite and many minor minerals. Olivine and mesostasis glass are partially replaced by veinlets and patches of iddingsite, a mixture of smectite clays, iron oxy-hydroxides and carbonate minerals. In the mesostasis are rare patches of a salt alteration assemblage: halite, siderite, and anhydrite/ gypsum. The nakhlites are little shocked, but have been affected chemically and biologically by their residence on Earth. Differences among the chemical compositions of the nakhlites can be ascribed mostly to different proportions of augite, olivine, and mesostasis. Compared to common basalts, they are rich in Ca, strongly depleted in Al, and enriched in magmaphile (incompatible) elements, including the LREE. Nakhlites contain little pre-terrestrial organic matter. Oxygen isotope ratios are not terrestrial, and are different in anhydrous silicates and in iddingsite. The alteration assemblages all have heavy oxygen and heavy carbon, while D/H values are extreme and scattered. Igneous sulfur had a solar-system isotopic ratio, but in most minerals was altered to higher and lower values. High precision

  5. Determination and distribution of diesel components in igneous rock surrounding underground diesel storage facilities in Sweden.

    PubMed

    Loren, A; Hallbeck, L; Pedersen, K; Abrahamsson, K

    2001-01-15

    In Sweden, a preliminary investigation of the contamination situation of igneous rock surrounding underground storage facilities of diesel showed that the situation was severe. The diesel was believed to have penetrated into the rock as far as 50 m from the walls of the vaults. Consequently, the risk for contamination of groundwater and recipients could not be neglected. To be able to assess the fate of diesel components in rock, both a suitable drilling method and a method for the determination of a wide range of diesel components were needed. The analytical method presented made it possible to quantify a number of hydrocarbons in rock samples collected with triple-tube core drilling. The samples were dissolved in hydrofluoric acid (HF) with hexane in Teflon centrifuge tubes. After digestion of the rock, extraction of the analytes with hexane was performed. Determination of the individual hydrocarbons present was done with gas chromatography-mass spectrometry (GC-MS). The method was used to study the environmental impact of the underground storage of diesel. The drilling method enabled sampling without contamination risks. Our data show that the major transport of diesel components in rock occurs through fracture systems and that diffusion of diesel through the rock is of minor importance. The results have drastically changed the view of the contamination situation of diesel in the vicinity of storage facilities in hard rock in Sweden.

  6. Pristine Igneous Rocks and the Early Differentiation of Planetary Materials

    NASA Technical Reports Server (NTRS)

    Warren, Paul H.

    1998-01-01

    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. Most of the accessible lunar crust consists of materials hybridized by impact-mixing. Rare pristine (unmixed) samples reflect the original genetic diversity of the early crust. We studied the relative importance of internally generated melt (including the putative magma ocean) versus large impact melts in early lunar magmatism, through both sample analysis and physical modeling. Other topics under investigation included: lunar and SNC (martian?) meteorites; igneous meteorites in general; impact breccias, especially metal-rich Apollo samples and polymict eucrites; effects of regolith/megaregolith insulation on thermal evolution and geochronology; and planetary bulk compositions and origins. We investigated the theoretical petrology of impact melts, especially those formed in large masses, such as the unejected parts of the melts of the largest lunar and terrestrial impact basins. We developed constraints on several key effects that variations in melting/displacement ratio (a strong function of both crater size and planetary g) have on impact melt petrology. Modeling results indicate that the impact melt-derived rock in the sampled, megaregolith part of the Moon is probably material that was ejected from deeper average levels than the non-impact-melted material (fragmental breccias and unbrecciated pristine rocks). In the largest lunar impacts, most of the impact melt is of mantle origin and avoids ejection from the crater, while most of the crust, and virtually all of the impact-melted crust, in the area of the crater is ejected. We investigated numerous extraordinary meteorites and Apollo rocks, emphasizing pristine rocks, siderophile and volatile trace elements, and the identification of primary partial melts, as opposed to partial cumulates. Apollo 15 sample 15434,28 is an

  7. Crystal Size Distributions in Igneous rocks: Where are we now?

    NASA Astrophysics Data System (ADS)

    Higgins, M.

    2003-12-01

    in either slope of intercept is significant and can be related to other parameters. Concave down CSDs, with no small crystals, are commonly encountered in porphyritic, oikocrystic and plutonic rocks. This texture may be produced by textural coarsening (Ostwald ripening, annealing): this occurs when the magma is maintained close to the mineral liquidus. In this situation the nucleation rate is zero, but growth rates are significant. The classic LSW model is not the only solution possible: more modern solutions, such as Communicating Neighbours may be more appropriate. Variable degrees of textural coarsening will produce CSDs that appear to rotate about a single point. This again reflects closure. Concave up CSDs with no lower size limit are very common. They do not generally have a lognormal or fractal size distribution. They can be produced by mixing of two or more magmas, or crystallisation under several different conditions of undercooling. They can also result from alternations of nucleation and growth followed by textural coarsening. Crystal accumulation and fraction should modify existing CSDs in a predictable manner. An exact solution to this problem has not yet been developed, but simplistic models suggest that CSDs should rotate upwards about the size origin for accumulation and downwards for fractionation. However, clear evidence for such effects has not yet been observed, even in well-layered rocks. There are many igneous systems still to be explored using CSDs. An exiting new domain may be the application of CSDs in experimental petrology.

  8. 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.

  9. Rb-Sr age of lunar igneous rocks 62295 and 14310

    NASA Technical Reports Server (NTRS)

    Mark, R. K.; Lee-Hu, C.-N.; Wetherill, G. W.

    1974-01-01

    Measurements of Rb-Sr ages of crystallization performed on igneous lunar highland rocks 62295 and 14310 are reported. Lunar sample 62295 is a mesostasis-rich spinel-troctolite very-high-alumina basalt exhibiting a variable igneous structure. Sample 14310 is a feldspathic KREEP-rich basalt. The determined ages probably date the cooling of shock melts.

  10. Classification scheme for sedimentary and igneous rocks in Gale crater, Mars

    NASA Astrophysics Data System (ADS)

    Mangold, N.; Schmidt, M. E.; Fisk, M. R.; Forni, O.; McLennan, S. M.; Ming, D. W.; Sautter, V.; Sumner, D.; Williams, A. J.; Clegg, S. M.; Cousin, A.; Gasnault, O.; Gellert, R.; Grotzinger, J. P.; Wiens, R. C.

    2017-03-01

    Rocks analyzed by the Curiosity rover in Gale crater include a variety of clastic sedimentary rocks and igneous float rocks transported by fluvial and impact processes. To facilitate the discussion of the range of lithologies, we present in this article a petrological classification framework adapting terrestrial classification schemes to Mars compositions (such as Fe abundances typically higher than for comparable lithologies on Earth), to specific Curiosity observations (such as common alkali-rich rocks), and to the capabilities of the rover instruments. Mineralogy was acquired only locally for a few drilled rocks, and so it does not suffice as a systematic classification tool, in contrast to classical terrestrial rock classification. The core of this classification involves (1) the characterization of rock texture as sedimentary, igneous or undefined according to grain/crystal sizes and shapes using imaging from the ChemCam Remote Micro-Imager (RMI), Mars Hand Lens Imager (MAHLI) and Mastcam instruments, and (2) the assignment of geochemical modifiers based on the abundances of Fe, Si, alkali, and S determined by the Alpha Particle X-ray Spectrometer (APXS) and ChemCam instruments. The aims are to help understand Gale crater geology by highlighting the various categories of rocks analyzed by the rover. Several implications are proposed from the cross-comparisons of rocks of various texture and composition, for instance between in place outcrops and float rocks. All outcrops analyzed by the rover are sedimentary; no igneous outcrops have been observed. However, some igneous rocks are clasts in conglomerates, suggesting that part of them are derived from the crater rim. The compositions of in-place sedimentary rocks contrast significantly with the compositions of igneous float rocks. While some of the differences between sedimentary rocks and igneous floats may be related to physical sorting and diagenesis of the sediments, some of the sedimentary rocks (e

  11. Igneous rock from Severnyi Kolchim (H3) chondrite: Nebular origin

    NASA Technical Reports Server (NTRS)

    Nazarov, M. A.; Brandstaetter, F.; Kurat, G.

    1993-01-01

    The discovery of lithic fragments with compositions and textures similar to igneous differentiates in unequilibrated ordinary chondrites (UOC's) and carbonaceous chondrites (CC's) has been interpreted as to suggest that planetary bodies existed before chondrites were formed. As a consequence, chondrites (except, perhaps CI chondrites) cannot be considered primitive assemblages of unprocessed nebular matter. We report about our study of an igneous clast from the Severnyi Kolchim (H3) chondrite. The results of the study are incompatible with an igneous origin of the clast but are in favor of a nebular origin similar to that of chondrules.

  12. Rock property measurements and analysis of selected igneous, sedimentary, and metamorphic rocks from worldwide localities

    USGS Publications Warehouse

    Johnson, Gordon R.

    1983-01-01

    Dry bulk density and grain density measurements were made on 182 samples of igneous, sedimentary, and metamorphic rocks from various world-wide localities. Total porosity values and both water-accessible and helium-accessible porosities were calculated from the density data. Magnetic susceptibility measurements were made on the solid samples and permeability and streaming potentials were concurrently measured on most samples. Dry bulk densities obtained using two methods of volume determination, namely direct measurement and Archlmedes principle, were nearly equivalent for most samples. Grain densities obtained on powdered samples were typically greater than grain densities obtained on solid samples, but differences were usually small. Sedimentary rocks had the highest percentage of occluded porosity per rock volume whereas metamorphic rocks had the highest percentage of occluded porosity per total porosity. There was no apparent direct relationship between permeability and streaming potential for most samples, although there were indications of such a relationship in the rock group consisting of granites, aplites, and syenites. Most rock types or groups of similar rock types of low permeability had, when averaged, comparable levels of streaming potential per unit of permeability. Three calcite samples had negative streaming potentials.

  13. Heat production rate from radioactive elements in igneous and metamorphic rocks in Eastern Desert, Egypt.

    PubMed

    Abbady, Adel G E; El-Arabi, A M; Abbady, A

    2006-01-01

    Radioactive heat-production data of Igneous and Metamorphic outcrops in the Eastern Desert are presented. Samples were analysed using a low level gamma-ray spectrometer (HPGe) in the laboratory. A total of 205 rock samples were investigated, covering all major rock types of the area. The heat-production rate of igneous rocks ranges from 0.11 (basalt) to 9.53 microWm(-3) (granite). In metamorphic rocks it varies from 0.28 (serpentinite ) to 0.91 microWm(-3) (metagabbro). The contribution due to U is about 51%, as that from Th is 31% and 18% from K. The corresponding values in igneous rocks are 76%, 19% and 5%, respectively. The calculated values showed good agreement with global values except in some areas containing granites.

  14. [High Precision Identification of Igneous Rock Lithology by Laser Induced Breakdown Spectroscopy].

    PubMed

    Wang, Chao; Zhang, Wei-gang; Yan, Zhi-quan

    2015-09-01

    In the field of petroleum exploration, lithology identification of finely cuttings sample, especially high precision identification of igneous rock with similar property, has become one of the geological problems. In order to solve this problem, a new method is proposed based on element analysis of Laser-Induced Breakdown Spectroscopy (LIBS) and Total Alkali versus Silica (TAS) diagram. Using independent LIBS system, factors influencing spectral signal, such as pulse energy, acquisition time delay, spectrum acquisition method and pre-ablation are researched through contrast experiments systematically. The best analysis conditions of igneous rock are determined: pulse energy is 50 mJ, acquisition time delay is 2 μs, the analysis result is integral average of 20 different points of sample's surface, and pre-ablation has been proved not suitable for igneous rock sample by experiment. The repeatability of spectral data is improved effectively. Characteristic lines of 7 elements (Na, Mg, Al, Si, K, Ca, Fe) commonly used for lithology identification of igneous rock are determined, and igneous rock samples of different lithology are analyzed and compared. Calibration curves of Na, K, Si are generated by using national standard series of rock samples, and all the linearly dependent coefficients are greater than 0.9. The accuracy of quantitative analysis is investigated by national standard samples. Element content of igneous rock is analyzed quantitatively by calibration curve, and its lithology is identified accurately by the method of TAS diagram, whose accuracy rate is 90.7%. The study indicates that LIBS can effectively achieve the high precision identification of the lithology of igneous rock.

  15. Hydrocarbon occurrences in igneous and metamorphic rocks: Plays of the 1990s

    SciTech Connect

    Harrelson, D.W.

    1989-09-01

    A review of available geologic literature has indicated numerous references detailing the occurrences of hydrocarbon in igneous and metamorphic rocks. Notable among these references is a paper by Chung-Hsiang P'an and a group of papers edited by Sidney Powers. Collectively, these papers conclude a biogenic source for hydrocarbons, most of which occur in (1) weathered igneous and metamorphic reservoir rocks that are higher than the source rocks (e.g., Amarillo field) or (2) igneous and metamorphic rocks that exert structural or stratigraphic control on the reservoir or source rocks (e.g., Jackson dome and the Wiggins anticline-Hancock ridge). It should be noted that a new twist on the abiogenic origin of some inert hydrocarbon gases (i.e., helium and nitrogen) proposes a degassing of igneous and metamorphic rocks from sources in the underlying mantle. Recent european super-deep tests (e.g., the Siljan Ring and the Kola SG-3 testholes) have attempted, with mixed results, to verify this theory. Drilling for these deep igneous and metamorphic prospects today is considered at or below economic basement or worse - a rank wildcat. However, these plays should become increasingly commercial in the 1990s as deeper drilling technology progresses, the current oil glut is eliminated, and more exotic deep gas prospects become accepted.

  16. Sources of Mesoproterozoic igneous rocks and formation time of the continental crust of the Kokchetav Massif (Northern Kazakhstan)

    NASA Astrophysics Data System (ADS)

    Tretyakov, A. A.; Kovach, V. P.; Degtyarev, K. E.; Shatagin, K. N.

    2016-12-01

    Within the Kokchetav massif (Northern Kazakhstan), Mesoproterozoic granites and acid volcanics are widespread: these are the youngest Precambrian igneous rocks forming basement of the region. The Nd isotopic characteristics (ɛNd( t)-4.4 ÷-9.6, t Nd(DM) 2.1-2.6 Ga) obtained for these rocks indicate that the source of their melts was the Early Precambrian continental crust. Thus, the continental crust of the Kokchetav Massif had basically been formed by the beginning of the Mesoproterozoic and during the Late Precambrian: later it became a source for the granitoid melts.

  17. Distribution of Igneous Rocks in Medina and Uvalde Counties, Texas, as Inferred from Aeromagnetic Data

    USGS Publications Warehouse

    Smith, David V.; McDougal, Robert R.; Smith, Bruce D.; Blome, Charles D.

    2008-01-01

    A high-resolution aeromagnetic survey was flown in 2001 over Medina and Uvalde Counties, Texas, as part of a multi-disciplinary investigation of the geohydrologic framework of the Edwards aquifer in south-central Texas. The objective of the survey was to assist in mapping structural features that influence aquifer recharge and ground-water flow. The survey revealed hundreds of magnetic anomalies associated with igneous rocks that had previously been unmapped. This report presents an interpretation of the outcrops and subcrops of igneous rocks, based upon procedures of matched-filtering and potential field modeling.

  18. Analysis and Discrimination of Sedimentary, Metamorphic, and Igneous Rocks Using Laser-Induced Breakdown Spectroscopy

    NASA Astrophysics Data System (ADS)

    Rai, Ab. Kr.; Maurya, G. S.; Kumar, R.; Pathak, A. K.; Pati, J. K.; Rai, Aw. K.

    2017-01-01

    This study deals with the analysis of rocks using laser-induced breakdown spectroscopy (LIBS) coupled with principal component analysis. The spectra of sedimentary, metamorphic, and igneous rock samples were recorded in the 200-900 nm spectral range. The atomic lines of elements such as Si, Ca, Mg, Fe, Na, and K along with lighter elements, namely C, H, N, and O, were observed in these spectra. Multivariate analysis in combination with LIBS was used to classify the samples. For principal component analysis, a 12 × 5849 data matrix was formed using the results of LIBS. The plot of the analysis revealed similarities between the sedimentary and metamorphic rock samples compared with the igneous rock sample. Thus, the present study demonstrates that LIBS coupled with principal component analysis can become an important tool for rapid classification and in-situ discrimination of rock samples.

  19. Strength/Brittleness Classification of Igneous Intact Rocks Based on Basic Physical and Dynamic Properties

    NASA Astrophysics Data System (ADS)

    Aligholi, Saeed; Lashkaripour, Gholam Reza; Ghafoori, Mohammad

    2017-01-01

    This paper sheds further light on the fundamental relationships between simple methods, rock strength, and brittleness of igneous rocks. In particular, the relationship between mechanical (point load strength index I s(50) and brittleness value S 20), basic physical (dry density and porosity), and dynamic properties (P-wave velocity and Schmidt rebound values) for a wide range of Iranian igneous rocks is investigated. First, 30 statistical models (including simple and multiple linear regression analyses) were built to identify the relationships between mechanical properties and simple methods. The results imply that rocks with different Schmidt hardness (SH) rebound values have different physicomechanical properties or relations. Second, using these results, it was proved that dry density, P-wave velocity, and SH rebound value provide a fine complement to mechanical properties classification of rock materials. Further, a detailed investigation was conducted on the relationships between mechanical and simple tests, which are established with limited ranges of P-wave velocity and dry density. The results show that strength values decrease with the SH rebound value. In addition, there is a systematic trend between dry density, P-wave velocity, rebound hardness, and brittleness value of the studied rocks, and rocks with medium hardness have a higher brittleness value. Finally, a strength classification chart and a brittleness classification table are presented, providing reliable and low-cost methods for the classification of igneous rocks.

  20. Classification Scheme for Diverse Sedimentary and Igneous Rocks Encountered by MSL in Gale Crater

    NASA Technical Reports Server (NTRS)

    Schmidt, M. E.; Mangold, N.; Fisk, M.; Forni, O.; McLennan, S.; Ming, D. W.; Sumner, D.; Sautter, V.; Williams, A. J.; Gellert, R.

    2015-01-01

    The Curiosity Rover landed in a lithologically and geochemically diverse region of Mars. We present a recommended rock classification framework based on terrestrial schemes, and adapted for the imaging and analytical capabilities of MSL as well as for rock types distinctive to Mars (e.g., high Fe sediments). After interpreting rock origin from textures, i.e., sedimentary (clastic, bedded), igneous (porphyritic, glassy), or unknown, the overall classification procedure (Fig 1) involves: (1) the characterization of rock type according to grain size and texture; (2) the assignment of geochemical modifiers according to Figs 3 and 4; and if applicable, in depth study of (3) mineralogy and (4) geologic/stratigraphic context. Sedimentary rock types are assigned by measuring grains in the best available resolution image (Table 1) and classifying according to the coarsest resolvable grains as conglomerate/breccia, (coarse, medium, or fine) sandstone, silt-stone, or mudstone. If grains are not resolvable in MAHLI images, grains in the rock are assumed to be silt sized or smaller than surface dust particles. Rocks with low color contrast contrast between grains (e.g., Dismal Lakes, sol 304) are classified according to minimum size of apparent grains from surface roughness or shadows outlining apparent grains. Igneous rocks are described as intrusive or extrusive depending on crystal size and fabric. Igneous textures may be described as granular, porphyritic, phaneritic, aphyric, or glassy depending on crystal size. Further descriptors may include terms such as vesicular or cumulate textures.

  1. Biological energy from the igneous rock enhances cell growth and enzyme activity.

    PubMed

    Lin, Y; Kuo, H; Chen, C; Kuo, S

    2000-08-01

    Some effects from natural resources might be ignored and unused by humans. Environmental hormesis could be a phenomena necessary to bio-organism existence on earth. Since 1919, radiation and some heavy metal hormesis from the environment were proved in various reports. In this study, igneous rock with very low radioactivity and high ferrous activity was measured by multichannel analyzer and inductively coupled plasma analyzer. The water treated by igneous rock, both directly soaked or indirectly in contact, induced increased activities of glucose oxidase, catalase, peroxidase, and superoxide dismutase. It also increased cell growth of SC-M1, HCT-15, Raji, and fibroblast cell lines. The water after treatment of igneous rock had no change in pH values, but displayed decreased conductivity values. We assume that the igneous rock could transfer energy to water to change the molecular structure or conformation of water cluster, or by radiation hormesis effect could then induce increased enzyme activity and cell growth. It is also possible that the energy from rock may combine radiation hormesis with other transferable biological energy forms to change water cluster conformation.

  2. Middle Jurassic to early Cretaceous igneous rocks along eastern North American continental margin

    SciTech Connect

    Jansa, L.F.; Pe-Piper, G.

    1988-03-01

    Late Middle Jurassic and Early Cretaceous mafic dikes, sills, flows, and local volcaniclastic sediments are intercalated within continental shelf sediments from the Baltimore Canyon Trough northward to the Grand Banks of Newfoundland. The igneous rocks on the eastern North American margin are mainly alkali basalts of intraplate affinity. The late Middle Jurassic igneous activity was of short duration, at about 140 Ma, and was restricted to Georges Bank where it led to construction of several volcanic cones. The main period of igneous activity was concentrated at about 120 Ma in the Aptian/Berremian. The activity consists of dike swarms in Baltimore Canyon, occasional dikes on the Scotian Shelf, and the growth of stratovolcanoes on the Scotian Shelf and Grand Banks. Younger dikes (approx. 95 Ma) also are present on the Grand Banks. With regard to oil exploration on the continental margin, care must be taken to properly identify igneous and volcaniclastic rocks on mechanical logs, drill cuttings, and cores. Reflection seismic profiles can be used to map the areal extent of sills, flows, and low-angle dikes, which commonly show distinctive seismic responses. However, steeply dipping dikes generally produce little, if any, seismic response. Isotopic-age determinations of igneous rocks, combined with biostratigraphic-age determinations of adjacent strata, are invaluable for stratigraphic correlation, establishing chronology of seismic sequences, and analysis of basin sedimentation and tectonic history. 9 figures, 2 tables.

  3. Petrological and Geochemical Studies of the Igneous Rocks at Cerro EL Borrego, Chihuahua, Mexico

    NASA Astrophysics Data System (ADS)

    Estrada, V. M.; Espejel-Garcia, V. V.; Villalobos-Aragon, A.

    2013-05-01

    Cerro El Borrego, which is a hill composed of igneous rocks, is located 13.7 km to the SW of Chihuahua city, in northern Mexico. The coordinates of the hill are 28° 11' 07'' N latitude and 105° 33' 23'' W longitude. The study area is within the Basin and Range Physiographic Province, characterized by a complex tectonic-structural pattern, such as elongated ranges with folds and igneous rock formations of Paleogene age. A lava flow of Oligocene age is part of the large volcanic and plutonic activity at the early times of the Cenozoic, which occurred to the NW portion of Mexico. In Cerro El Borrego, the rocks that outcrop are middle Oligocene's rhyolitic tuff to the NW of the hill, while to its SE there is a Pleistocene polymictic conglomerate. Previous work shows different interpretations about the origin and composition of the igneous rocks at Cerro El Borrego. This project includes whole rock and textural analyses, which helped to discern the petrogenesis of these rocks. Preliminary petrographic analyses indicate that the Cerro El Borrego, is a structural dome, and its feldspar-rich rocks contain large crystals that can be appreciated without a microscope. The presence of a porphyritic texture, suggest a sallow intrusion origin. A preliminary conclusion is that Cerro El Borrego is a shallow depth intrusive body with a syenitic composition derived from the Oligocene plutonic activity.

  4. Siderophile and volatile trace elements in 72255 and 72275. [meteoritic and igneous composition of lunar rocks

    NASA Technical Reports Server (NTRS)

    Morgan, J. W.; Ganapathy, R.; Higuchi, H.; Anders, E.

    1974-01-01

    Of six samples from boulder 1 at Station 2, four contain a unique meteoritic component, which is attributed to the Crisium projectile. The other two samples are meteorite free, igneous rocks: an unusual, alkali- and Ge-rich pigeonitic basalt, and an alkali-poor norite of unexceptional trace element chemistry.

  5. Spectral emission measurement of igneous rocks using a spectroradiometer

    NASA Technical Reports Server (NTRS)

    Hunton, W. D.

    1970-01-01

    Spectroradiometer is used for either close or remote identification of rocks not heated to high temperatures. Instrument yields reproducible data spectra with excellent signal-to-noise ratios and readily identifiable spectral details, including differences in subclasses.

  6. Continental igneous rock composition: A major control of past global chemical weathering

    PubMed Central

    Bataille, Clément P.; Willis, Amy; Yang, Xiao; Liu, Xiao-Ming

    2017-01-01

    The composition of igneous rocks in the continental crust has changed throughout Earth’s history. However, the impact of these compositional variations on chemical weathering, and by extension on seawater and atmosphere evolution, is largely unknown. We use the strontium isotope ratio in seawater [(87Sr/86Sr)seawater] as a proxy for chemical weathering, and we test the sensitivity of (87Sr/86Sr)seawater variations to the strontium isotopic composition (87Sr/86Sr) in igneous rocks generated through time. We demonstrate that the 87Sr/86Sr ratio in igneous rocks is correlated to the epsilon hafnium (εHf) of their hosted zircon grains, and we use the detrital zircon record to reconstruct the evolution of the 87Sr/86Sr ratio in zircon-bearing igneous rocks. The reconstructed 87Sr/86Sr variations in igneous rocks are strongly correlated with the (87Sr/86Sr)seawater variations over the last 1000 million years, suggesting a direct control of the isotopic composition of silicic magmatism on (87Sr/86Sr)seawater variations. The correlation decreases during several time periods, likely reflecting changes in the chemical weathering rate associated with paleogeographic, climatic, or tectonic events. We argue that for most of the last 1000 million years, the (87Sr/86Sr)seawater variations are responding to changes in the isotopic composition of silicic magmatism rather than to changes in the global chemical weathering rate. We conclude that the (87Sr/86Sr)seawater variations are of limited utility to reconstruct changes in the global chemical weathering rate in deep times. PMID:28345044

  7. Continental igneous rock composition: A major control of past global chemical weathering.

    PubMed

    Bataille, Clément P; Willis, Amy; Yang, Xiao; Liu, Xiao-Ming

    2017-03-01

    The composition of igneous rocks in the continental crust has changed throughout Earth's history. However, the impact of these compositional variations on chemical weathering, and by extension on seawater and atmosphere evolution, is largely unknown. We use the strontium isotope ratio in seawater [((87)Sr/(86)Sr)seawater] as a proxy for chemical weathering, and we test the sensitivity of ((87)Sr/(86)Sr)seawater variations to the strontium isotopic composition ((87)Sr/(86)Sr) in igneous rocks generated through time. We demonstrate that the (87)Sr/(86)Sr ratio in igneous rocks is correlated to the epsilon hafnium (εHf) of their hosted zircon grains, and we use the detrital zircon record to reconstruct the evolution of the (87)Sr/(86)Sr ratio in zircon-bearing igneous rocks. The reconstructed (87)Sr/(86)Sr variations in igneous rocks are strongly correlated with the ((87)Sr/(86)Sr)seawater variations over the last 1000 million years, suggesting a direct control of the isotopic composition of silicic magmatism on ((87)Sr/(86)Sr)seawater variations. The correlation decreases during several time periods, likely reflecting changes in the chemical weathering rate associated with paleogeographic, climatic, or tectonic events. We argue that for most of the last 1000 million years, the ((87)Sr/(86)Sr)seawater variations are responding to changes in the isotopic composition of silicic magmatism rather than to changes in the global chemical weathering rate. We conclude that the ((87)Sr/(86)Sr)seawater variations are of limited utility to reconstruct changes in the global chemical weathering rate in deep times.

  8. Classification and Geochemical Characterization of Igneous Rocks: Southern Part of Chihuahua City, Mexico

    NASA Astrophysics Data System (ADS)

    Fontes, I. D.; Espejel-Garcia, V. V.; Villalobos-Aragon, A.

    2013-05-01

    Chihuahua City is the capital of the state with the same name, located in northern Mexico. The city was established near the Chuviscar River, but in the last decades it has been extended to the nearby areas (mountains), with volcanic (rhyolitic tuffs), and sedimentary rocks (limestone). The study area includes areas in the south part of Chihuahua City, where we can still find unbuilt lands and it is possible to appreciate outcrops of igneous rocks. This project includes 5 study spots, which are located about 9 km. far from the south extreme of the city. This research is developed in order to complement the geological information in this area, as there is no is detailed record of it. In the geological map H13-10 (SGM, 1997), it is said that the urban area is covered by Quaternary conglomerates, while exploring the region we have located several igneous rocks outcrops. In three of the sampling points, dark colored intrusive igneous rocks with large crystals appear in blocks without noticeable fractures. While in the other two sampling points, highly fractured blocks of pink aphanitic igneous rocks, showing traces of pyrolusite were observed. The petrographic study shows the two different textures that classify these rocks as extrusive (aphanitic) or intrusive (phaneritic), both with quartz and feldspars being the dominant minerals. Geochemical analyses confirm the felsic composition of the rocks, varying form trachytes to rhyolites. The trace element results show high contents of Sr, Ba, V, Rb, and Zr in trachytic compositions, while there are high concentrations of Mn, W, Rb and Co for rhyolitic compositions.

  9. Igneous rocks of Arctic Ocean deep sea ridges: new data on petrology, geochemistry and geochronology

    NASA Astrophysics Data System (ADS)

    Petrov, Oleg; Morozov, Andrey; Shokalsky, Sergey; Sobolev, Nikolay; Kashubin, Sergey; Shevchenko, Sergey; Sergeev, Sergey; Belyatsky, Boris; Shatov, Vitaly; Petrov, Eugeny

    2015-04-01

    The aggregate results of studies of igneous rocks, collected from the central part of the Arctic Ocean during scientific marine expeditions «Arctic-2000, 2005, 2007 and 2012» are presented and discussed in the frame of modern understanding of High Polar Arctic tectonic constraint. Petrological, geochemical and isotope-geochronological studies of more than 500 samples have shown that the sedimentary rocks are of dominated population among the rock fragments dredged from deep-sea bottom, and represented by metamorphosed dolomite and quartz sandstone, limestone, sometimes with the Devonian - Permian fauna. Igneous rocks are 10-15% only (Archean and Paleoproterozoic gneissouse granites and gabbro, Neoproterozoic dolerite) and metamorphic rocks (green shales, metabasites, gneisses). Apparently, these rocks are part of the acoustic basement underlying the Late Mesozoic - Cenozoic layered loose sediments. In addition to the dredged fragments of the ancient mafic rocks, some samples were taken as a core during deep-water drilling in the northern and southern slopes of the Mendeleev Ridge and represented by trachybasalts, marking the border of Late-Cenozoic deposit cover and acoustic basement and quite similar in composition to those of Early-Late Cretaceous basalts form northward of the Chukchi Plateau seamounts, Alpha Ridge, Franz Josef Land, De Long islands and other parts of the large igneous province of the High Arctic (HALIP). Video-filming of Mendeleev Ridge escarps proofs the existing of rock outcrops and supports local origin of most of the rock fragments found in the sampling areas. Thus the continental type of the earth's crust of the Central Arctic Ridges basement is based on all obtained results of our study of sea-bottom excavated rock material.

  10. Pristine Igneous Rocks and the Early Differentiation of Planetary Materials

    NASA Technical Reports Server (NTRS)

    Warren, Paul H.

    2005-01-01

    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. Most of the accessible lunar crust consists of materials hybridized by impact-mixing. Our lunar research concentrates on the rare pristine (unmixed) samples that reflect the original genetic diversity of the early crust. Among HED basalts (eucrites and clasts in howardites), we distinguish as pristine the small minority that escaped the pervasive thermal metamorphism of the parent asteroid's crust. We have found a correlation between metamorphically pristine HED basalts and the similarly small minority of compositionally evolved "Stannern trend" samples, which are enriched in incompatible elements and titanium compared to main group eucrites, and yet have relatively high mg ratios. Other topics under investigation included: lunar and SNC (martian?) meteorites; igneous meteorites in general; impact breccias, especially metal-rich Apollo samples and polymict eucrites; siderophile compositions of the lunar and martian mantles; and planetary bulk compositions and origins.

  11. Thermal Conductivity Anisotropy of Metasedimentary and Igneous Rocks

    NASA Astrophysics Data System (ADS)

    Davis, M. G.; Chapman, D. S.; van Wagoner, T. M.; Armstrong, P. A.

    2005-12-01

    Thermal conductivity anisotropy was determined for two sets of rocks: a series of sandstones, mudstones, and limey shales of Cretaceous age from Price Canyon, Utah, and metasedimentary argillites and quartzites of Precambrian age from the Big Cottonwood Formation in north central Utah. Additional anisotropy measurements were made on granitic rocks from two Tertiary plutons in Little Cottonwood Canyon, north central Utah. Most conductivity measurements were made in transient mode with a half-space, line-source instrument oriented in two orthogonal directions on a flat face cut perpendicular to bedding. One orientation of the probe yields thermal conductivity parallel to bedding (kmax) directly, the other orientation of the probe measures a product of conductivities parallel and perpendicular to bedding from which the perpendicular conductivity (kperp) is calculated. Some direct measurements of kmax and kperp were made on oriented cylindrical discs using a conventional divided bar device in steady-state mode. Anisotropy is defined as kmax/kperp. The Precambrian argillites from Big Cottonwood Canyon have anisotropy values from 0.8 to 2.1 with corresponding conductivity perpendicular to bedding of 2.0 to 6.2 W m-1 K-1. Anisotropy values for the Price Canyon samples are less than 1.2 with a mean of 1.04 although thermal conductivity perpendicular to bedding for the samples varied from 1.3 to 5.0 W m-1 K-1. The granitic rocks were found to be essentially isotropic with thermal conductivity perpendicular to bedding having a range of 2.2 to 3.2 W m-1 K-1 and a mean of 2.68 W m-1 K-1. The results confirm the observation by Deming (1994) that anisotropy is negligible for rocks having kperp greater than 4.0 W m-1 K-1 and generally increases for low conductivity metamorphic and clay-rich rocks. There is little evidence, however, for his suggestion that thermal conductivity anisotropy of all rocks increases systematically to about 2.5 for low thermal conductivity rocks.

  12. Geochemical microanalysis: The link between textural and geochemical characterization of igneous rocks

    NASA Astrophysics Data System (ADS)

    Kent, A. J.

    2003-12-01

    In this presentation I will review recent advances in microanalytical techniques that allow us to directly couple textural and geochemical information to the study of igneous rocks, particularly with respect to the analysis of silicate melt inclusions. Textural examination has long been a mainstay of the classification and petrologic study of igneous materials. The advent of the electron microprobe over 50 years ago allowed textural and geochemical observations to be coupled at small spatial scales and directly related to the physical and chemical conditions of formation and subsequent melt evolution. This resulted in a revolution in the petrological investigation and understanding of igneous rocks that continues today. Recent advances in geochemical microanalysis techniques are providing exciting access to new geochemical information at smaller and smaller spatial scales. These are enabling measurement of the abundances, and in some cases isotopic compositions, of a range of elements in correspondingly smaller sample volumes. A case in point is the study of silicate melt inclusions. Although melt inclusions have been recognized and studied for over a century, there has been a recent surge in interest directly tied to development of techniques capable of performing in-situ analysis of trace element and volatile components at small spatial scales. Melt inclusions allow direct sampling of melts present during crystal formation, and are particularly useful for relating crystal textures and compositions to those of their source melts. Chemical compositions of melt inclusions reveal the diversity of igneous compositions present in igneous systems, and may be combined with textural observations to constrain a wide range of igneous processes, including degassing, assimilation, fractional crystallization and mixing.

  13. Log-ratio transformed major element based multidimensional classification for altered High-Mg igneous rocks

    NASA Astrophysics Data System (ADS)

    Verma, Surendra P.; Rivera-Gómez, M. Abdelaly; Díaz-González, Lorena; Quiroz-Ruiz, Alfredo

    2016-12-01

    A new multidimensional classification scheme consistent with the chemical classification of the International Union of Geological Sciences (IUGS) is proposed for the nomenclature of High-Mg altered rocks. Our procedure is based on an extensive database of major element (SiO2, TiO2, Al2O3, Fe2O3t, MnO, MgO, CaO, Na2O, K2O, and P2O5) compositions of a total of 33,868 (920 High-Mg and 32,948 "Common") relatively fresh igneous rock samples. The database consisting of these multinormally distributed samples in terms of their isometric log-ratios was used to propose a set of 11 discriminant functions and 6 diagrams to facilitate High-Mg rock classification. The multinormality required by linear discriminant and canonical analysis was ascertained by a new computer program DOMuDaF. One multidimensional function can distinguish the High-Mg and Common igneous rocks with high percent success values of about 86.4% and 98.9%, respectively. Similarly, from 10 discriminant functions the High-Mg rocks can also be classified as one of the four rock types (komatiite, meimechite, picrite, and boninite), with high success values of about 88%-100%. Satisfactory functioning of this new classification scheme was confirmed by seven independent tests. Five further case studies involving application to highly altered rocks illustrate the usefulness of our proposal. A computer program HMgClaMSys was written to efficiently apply the proposed classification scheme, which will be available for online processing of igneous rock compositional data. Monte Carlo simulation modeling and mass-balance computations confirmed the robustness of our classification with respect to analytical errors and postemplacement compositional changes.

  14. Termination time of peak decratonization in North China: Geochemical evidence from mafic igneous rocks

    NASA Astrophysics Data System (ADS)

    Dai, Li-Qun; Zheng, Yong-Fei; Zhao, Zi-Fu

    2016-01-01

    Geophysical and petrological data indicate destruction of the cratonic lithosphere in North China in the Mesozoic, resulting in replacement of the ancient subcontinental lithospheric mantle (SCLM) by the juvenile SCLM. However, it remains to be answered when the craton destruction would have been terminated in the Mesozoic. This question is resolved by studying the two types of mafic igneous rocks with contrasting geochemical compositions from North China. The first type of mafic igneous rock shows arc-like trace element distribution patterns and enriched radiogenic Sr-Nd isotope compositions, with emplacement ages spanning from the Triassic to Early Cretaceous. The mafic magmatism is absent in a period from 200 Ma to 135 Ma, recording the thinning of cratonic lithosphere due to the westward flat subduction of the Paleo-Pacific slab beneath the North China Craton. In contrast, the second type of mafic igneous rocks exhibits oceanic island basalts (OIB)-like trace element distribution patterns and relatively depleted radiogenic Sr-Nd isotope compositions, with emplacement ages spanning from the Early Cretaceous to Cenozoic. Zircon U-Pb dating yields an age of 121 Ma for the geochemical transformation between the two types of mafic igneous rocks. This age marks a dramatic demarcation in the composition of their mantle sources. As such, the nature of mantle lithosphere in North China was changed from the ancient SCLM to the juvenile SCLM at 121 Ma. Thus, this age not only signifies the tectonic transition from the enriched mantle to the depleted mantle in the Early Cretaceous, but also dates the termination of peak decratonization in North China. Therefore, the craton destruction in the Early Cretaceous is temporally and spatially associated with the dramatic changes in the geochemical composition of mantle lithosphere.

  15. Lead isotope systematics of some igneous rocks from the Egyptian Shield

    NASA Technical Reports Server (NTRS)

    Gillespie, J. G.; Dixon, T. H.

    1983-01-01

    Lead isotope data on whole-rock samples and two feldspar separates for a variety of Pan-African (late Precambrian) igneous rocks for the Egyptian Shield are presented. It is pointed out that the eastern desert of Egypt is a Late Precambrian shield characterized by the widespread occurrence of granitic plutons. The lead isotope ratios may be used to delineate boundaries between Late Precambrian oceanic and continental environments in northeastern Africa. The samples belong to three groups. These groups are related to a younger plutonic sequence of granites and adamellites, a plutonic group consisting of older tonalites to granodiorites, and the Dokhan volcanic suite.

  16. Distinct Igneous APXS Rock Compositions on Mars from Pathfinder, MER and MSL

    NASA Technical Reports Server (NTRS)

    Gellert, Ralf; Arvidson, Raymond; Clark, Benton, III; Ming, Douglas W.; Morris, Richard V.; Squyres, Steven W.; Yen, Albert S.

    2015-01-01

    The alpha particle x-ray spectrometer (APXS) on all four Mars Rovers returned geochemical data from about 1000 rocks and soils along the combined traverses of over 50 kilometers. Here we discuss rocks likely of igneous origin, which might represent source materials for the soils and sediments identified along the traverses. Adirondack-type basalts, abundant in the plains of Gusev Crater, are primitive, olivine bearing basalts. They resemble in composition the basaltic soils encountered at all landing sites, except the ubiquitous elevated S, Cl and Zn in soils. They have been postulated to represent closely the average Martian crust composition. The recently identified new Martian meteorite Black Beauty has similar overall geochemical composition, very distinct from the earlier established SNC meteorites. The rim of the Noachian crater Endeavour, predating the sulfate-bearing Burns formation at Meridiani Planum, also resembles closely the composition of Adirondack basalts. At Gale Crater, the MSL Curiosity rover identified a felsic rock type exemplified by the mugearitic float rock JakeM, which is widespread along the traverse at Gale. While a surprise at that time, possibly related more evolved, alkaline rocks had been previously identified on Mars. Spirit encountered the Wishstone rocks in the Columbia Hills with approx. 6% Na2O+K2O, 15 % Al2O3 and low 12% FeO. Pathfinder rocks with elevated K and Na and >50% SiO2 were postulated to be andesitic. Recently Opportunity encountered the rock JeanBaptisteCharbonneau with >15% Al2O3, >50% SiO2 and approx. 10% FeO. A common characteristic all these rocks is the very low abundance of Cr, Ni and Zn, and an Fe/Mn ratio of about 50, indicating an unaltered Fe mineralogy. Beside these likely igneous rock types, which occurred always in several rocks, a few unique rocks were encountered, e.g. Bounce Rock, a pyroxene-bearing ejecta rock fragment resembling the Shergottite EETA 79001B meteorite. The APXS data can be used to

  17. Geochemical Database for Igneous Rocks of the Ancestral Cascades Arc - Southern Segment, California and Nevada

    USGS Publications Warehouse

    du Bray, Edward A.; John, David A.; Putirka, Keith; Cousens, Brian L.

    2009-01-01

    Volcanic rocks that form the southern segment of the Cascades magmatic arc are an important manifestation of Cenozoic subduction and associated magmatism in western North America. Until recently, these rocks had been little studied and no systematic compilation of existing composition data had been assembled. This report is a compilation of all available chemical data for igneous rocks that constitute the southern segment of the ancestral Cascades magmatic arc and complement a previously completed companion compilation that pertains to rocks that constitute the northern segment of the arc. Data for more than 2,000 samples from a diversity of sources were identified and incorporated in the database. The association between these igneous rocks and spatially and temporally associated mineral deposits is well established and suggests a probable genetic relationship. The ultimate goal of the related research is an evaluation of the time-space-compositional evolution of magmatism associated with the southern Cascades arc segment and identification of genetic associations between magmatism and mineral deposits in this region.

  18. Postcollisional mafic igneous rocks record crust-mantle interaction during continental deep subduction.

    PubMed

    Zhao, Zi-Fu; Dai, Li-Qun; Zheng, Yong-Fei

    2013-12-04

    Findings of coesite and microdiamond in metamorphic rocks of supracrustal protolith led to the recognition of continental subduction to mantle depths. The crust-mantle interaction is expected to take place during subduction of the continental crust beneath the subcontinental lithospheric mantle wedge. This is recorded by postcollisional mafic igneous rocks in the Dabie-Sulu orogenic belt and its adjacent continental margin in the North China Block. These rocks exhibit the geochemical inheritance of whole-rock trace elements and Sr-Nd-Pb isotopes as well as zircon U-Pb ages and Hf-O isotopes from felsic melts derived from the subducted continental crust. Reaction of such melts with the overlying wedge peridotite would transfer the crustal signatures to the mantle sources for postcollisional mafic magmatism. Therefore, postcollisonal mafic igneous rocks above continental subduction zones are an analog to arc volcanics above oceanic subduction zones, providing an additional laboratory for the study of crust-mantle interaction at convergent plate margins.

  19. Postcollisional mafic igneous rocks record crust-mantle interaction during continental deep subduction

    PubMed Central

    Zhao, Zi-Fu; Dai, Li-Qun; Zheng, Yong-Fei

    2013-01-01

    Findings of coesite and microdiamond in metamorphic rocks of supracrustal protolith led to the recognition of continental subduction to mantle depths. The crust-mantle interaction is expected to take place during subduction of the continental crust beneath the subcontinental lithospheric mantle wedge. This is recorded by postcollisional mafic igneous rocks in the Dabie-Sulu orogenic belt and its adjacent continental margin in the North China Block. These rocks exhibit the geochemical inheritance of whole-rock trace elements and Sr-Nd-Pb isotopes as well as zircon U-Pb ages and Hf-O isotopes from felsic melts derived from the subducted continental crust. Reaction of such melts with the overlying wedge peridotite would transfer the crustal signatures to the mantle sources for postcollisional mafic magmatism. Therefore, postcollisonal mafic igneous rocks above continental subduction zones are an analog to arc volcanics above oceanic subduction zones, providing an additional laboratory for the study of crust-mantle interaction at convergent plate margins. PMID:24301173

  20. A physical basis for remote rock mapping of igneous rocks using spectral variations in thermal infrared emittance

    NASA Technical Reports Server (NTRS)

    Walter, L. S.; Labovitz, M. L.

    1980-01-01

    Results of a theoretical investigation of the relation between spectral features in the 8-12 micrometer region and rock type are presented. Data on compositions of a suite of rocks and measurements of their spectral intensities in 8.2-10.9 and 9.4-12.1 micrometer bands published by Vincent (1973) were subjected to various quantitative procedures. There was no consistent direct relationship between rock group names and the relative spectral intensities. However, there is such a relationship between the Thornton-Tuttle (1960) Differentiation Index and the relative spectral intensities. This relationship is explicable on the basis of the change in average Si-O bond length which is a function of the degree of polymerization of the SiO4 tetrahedra of the silicate minerals in the igneous rocks.

  1. Microbial populations and activities in the rhizoplane of rock-weathering desert plants. I. Root colonization and weathering of igneous rocks.

    PubMed

    Puente, M E; Bashan, Y; Li, C Y; Lebsky, V K

    2004-09-01

    Dense layers of bacteria and fungi in the rhizoplane of three species of cactus (Pachycereus pringlei, Stenocereus thurberi, Opuntia cholla) and a wild fig tree (Ficus palmeri) growing in rocks devoid of soil were revealed by bright-field and fluorescence microscopy and field emission scanning electron microscopy. These desert plants are responsible for rock weathering in an ancient lava flow at La Purisima-San Isidro and in sedimentary rock in the Sierra de La Paz, both in Baja California Sur, Mexico. The dominant bacterial groups colonizing the rhizoplane were fluorescent pseudomonads and bacilli. Seven of these bacterial species were identified by the 16S rRNA molecular method. Unidentified fungal and actimomycete species were also present. Some of the root-colonizing microorganisms fixed in vitro N(2), produced volatile and non-volatile organic acids that subsequently reduced the pH of the rock medium in which the bacteria grew, and significantly dissolved insoluble phosphates, extrusive igneous rock, marble, and limestone. The bacteria were able to release significant amounts of useful minerals, such as P, K, Mg, Mn, Fe, Cu, and Zn from the rocks and were thermo-tolerant, halo-tolerant, and drought-tolerant. The microbial community survived in the rhizoplane of cacti during the annual 10-month dry season. This study indicates that rhizoplane bacteria on cacti roots in rock may be involved in chemical weathering in hot, subtropical deserts.

  2. Late Triassic, arc-related, potassic igneous rocks in the North American Cordillera

    NASA Astrophysics Data System (ADS)

    Mortimer, N.

    1986-12-01

    Igneous rocks of Late Triassic age are widespread in the Cordillera of western North America and, except in Wrangellia, consist of subduction-related plutonic and volcanic suites. Many of these, including those in the Stikinia, Quesnellia, Rattlesnake Creek, and Jackson terrenes and in southern California, are clinopyroxene rich and belong to high-potassium and shoshonitic rock series, features that are generally absent from older and younger igneous rocks in the same terranes. The Late Triassic subduction-related rocks are exposed in two discontinuous belts that lie east and west of the Cache Creek terrane in Canada and correlative melange terranes farther south. Stratigraphic and structural data suggest that these belts were spatially separate magmatic arcs in Late Triassic time. Tectonic implications of this analysis include an explanation of Middle Jurassic Cordilleran deformation as the result of collision of the western with the eastern belt, absence of Late Triassic links between Stikinia and Quesnellia, disassociation of Stikinia with terranes in northwestern Nevada, and tentative correlation of the Wallowa (Seven Devils) terrane with Stikinia rather than Wrangellia. *Present address: New Zealand Geological Survey, Department of Scientific and Industrial Research, Private Bag, Dunedin, New Zealand

  3. Diverse, Alkali-Rich Igneous and Volcaniclastic Rocks Reflect a Metasomatised Mantle Beneath Gale Crater

    NASA Astrophysics Data System (ADS)

    Schmidt, M. E.; Baker, M. B.; Berger, J. A.; Fisk, M. R.; Gellert, R.; McLennan, S. M.; Newcombe, M. E.; Stolper, E. M.; Thompson, L. M.

    2014-12-01

    Although Curiosity landed in a sedimentary setting, geochemical compositions determined by Alpha Particle X-ray Spectrometer (APXS) and ChemCam suggest that major element concentrations of some rocks were little modified by chemical weathering, and in these cases, the bulk (>70%) of the crystalline components determined by ChemMin are igneous. Gale rocks can therefore largely preserve the composition of their igneous protoliths and provide insight into the crystalline basement exposed in the north crater rim. Four end-member compositions are recognized on the basis of APXS analyses. (1) The diverse, evolved Jake M class (n=12) of inferred igneous origin includes float blocks and cobbles. Jake M rocks are phonotephritic/mugearitic to trachyandesitic and characterized by low MgO contents (3.0-5.7 wt%) and high Al and alkalis, particularly Na2O (up to 7.35 wt%). (2) The Bathurst class of siltstones to coarse sandstones (n=13) occurs as dark-toned float and bedded outcrop and is basaltic to trachybasaltic, ranging to high K2O (up to 3.8 wt%). Alteration of the protolith(s) or during diagenesis may have affected this class. (3) The Darwin class of conglomerates to coarse sandstones (n=10) has high Na and Al, likely reflecting a sodic plagioclase-rich mineralogy, but with higher Fe than Jake M class (13.0-17.1 vs. 6.0-12.5 wt%). (4) The low alkali "normal" Mars basaltic composition is typified by the Portage soils (n=6) and the John Klein class (n=13; includes the Sheepbed mudstone). Some degree of mixing and/or contamination with this low alkali basaltic compositon has affected all APXS analyses. Overall, Gale rocks are strongly enriched in total alkalis (at the same MgO) relative to basaltic shergottites and many have higher K2O than igneous rocks analyzed by Spirit and Opportunity, suggesting that the mantle beneath Gale is alkali-rich (likely as a result of a metasomatic event) and that alkalis are heterogeneously distributed in the planet's interior.

  4. Spectral characterization of igneous rocks in the 8- to 12-micron region

    NASA Technical Reports Server (NTRS)

    Walter, Louis S.; Salisbury, John W.

    1989-01-01

    This paper investigates the crystal-chemistry basis for the variation in spectral behavior of ingneous rocks, with the purpose of developing relationships useful for applications in the lithologic characterization of terrestrial and extraterrestrial surfaces. A new parameter is proposed for characterizing general rock and mineral type. The parameter, SCFM, defined as the ratio SiO2/(SiO2 + CaO + FeO + MgO), reflects the degree of depolymerization of the silica tetrahedra in both fine-grained and coarse-grained igneous rocks, and is a good descriptor of the composition of these rocks. Using spectra obtained in the laboratory on coarse-particulate mineral and solid-rock samples, the SCFM parameter was used to assess the effects of variations in the rock composition on the location, number, and width of spectral bands. A regression analysis of bands varying in width from 0.2 micron to 1.4 microns versus the SCFM value resulted in correlation coefficients ranging from 0.88 to 0.97.

  5. Stress Activation and Propagation of Electronic Charge Carriers in Igneous Rocks

    NASA Astrophysics Data System (ADS)

    Ling, J.; Freund, F. T.

    2007-12-01

    Igneous and high-grade metamorphic rocks in the Earth's crust generate electric currents when subjected to deviatoric stresses. The reason is that these rocks contain dormant electronic charge carriers in the form of peroxy links. Peroxy links are sites in the crystal structures of the constituent minerals where oxygen anions have converted from their common 2- valence state to the 1- valence state, O3X-OO-XO3 with X=Si4+, Al3+ etc. As rocks are stressed and dislocations sweep through the mineral grains, the peroxy links break up, activating electrons and pholes ("phole" is an abbreviation for "positive hole", a defect electron on the oxygen sublattice, chemically O- in a matrix of O2-). The pholes are mobile electronic charge carriers that can spread out of the stressed rock into the surrounding unstressed rock. They travel via energy levels at the upper edge of the valence bands, cross grain boundaries and achieve a phase velocity on the order of 200±50 m/sec, consistent with phonon-assisted electron hopping. Due to mutual repulsion inside the rock volume the pholes spread to the surface, where they build up a positive surface charge. The surface charge can be measured with a non-contact capacitive sensor. If a Cu contact is applied to the surface of the rock, electrons are injected from ground into the rock in response to the evolving positive charge on the rock surface. We modeled surface potentials and burst-like electron injections following low and medium velocity impact experiments, 100 m/sec and 1.5 km/sec respectively.

  6. Zirconolite: A new U-Pb chronometer for mafic igneous rocks

    NASA Astrophysics Data System (ADS)

    Rasmussen, Birger; Fletcher, Ian R.

    2004-09-01

    Precise dates for mafic igneous events are essential for tectonic reconstructions and understanding mantle dynamics, mass extinctions, and paleoclimate. Zirconolite (CaZrTi2O7) is a uranium-bearing accessory mineral, found in a wide range of terrestrial and lunar rocks, that has been largely overlooked as a chronometer. In situ U-Pb geochronology of zirconolite from three dolerite intrusions in Western Australia demonstrates that it yields emplacement ages that are more precise than those obtained from coexisting zircon and baddeleyite. Dikes in the Stirling Range Formation give a zirconolite 207Pb/ 206Pb age of 1218 ± 3 Ma, indistinguishable from the less precise dates obtained from zircon (1215 ± 10 Ma) and baddeleyite (1217 ± 39 Ma) and coincident with dike emplacement in the adjacent craton margin and peak metamorphism in the Albany-Fraser orogen. Zirconolite from the 755 Ma Mundine Well dike swarm yields a 207Pb/206Pb age of 754 ± 5 Ma. Sills intruding the Proterozoic Manganese Group contain zirconolite crystals that give a 207Pb/206Pb age of 523 ± 14 Ma. Despite high U contents (550 ppm to 14,000 ppm) and greenschist facies metamorphism, zirconolite in these samples is apparently unaffected by loss of radiogenic Pb. Because of its remarkable properties for U-Pb geochronology, it may soon become the dominant tool for dating mafic igneous rocks as young as 500 Ma by ion microprobe, and thus will prove especially valuable in reconstructing Precambrian geologic history.

  7. Magnetic petrofabric of igneous rocks: Lessons from pyroclastic density current deposits and obsidians

    NASA Astrophysics Data System (ADS)

    Cañón-Tapia, E.; Mendoza-Borunda, R.

    2014-12-01

    Measurement of the anisotropy of magnetic susceptibility (AMS) of igneous rocks can provide clues concerning their mechanism of formation and in particular are very helpful as flow direction indicators. Unlike other igneous rocks, however, pyroclastic density current deposits (PDCDs) present a challenge in the interpretation of AMS measurements due to the complexity of their mechanism of emplacement. In this paper we review the most common assumptions made in the interpretation of the AMS of PDCD, taking advantage of key lessons obtained from obsidians. Despite the complexities on the mechanism of formation of PDCDs, it is shown that a key element for the fruitful interpretation of AMS is to give proper attention to the various components likely to be involved in controlling their general petrofabric. The anisotropies of ferromagnetic crystals (whether as free phases or embedded within clasts or shards), and those of paramagnetic minerals (mainly ferrosilicates) need to be taken into consideration when interpreting the AMS measurements of PDCDs. Variations of the deposition regime both as a function of position and of time also need to be considered on the interpretations. Nevertheless, if a suitable sampling strategy is adopted, the potential of the AMS method as a petrofabric indicator is maximized.

  8. Felsic Igneous Rocks at Gale Crater : a Comparison with Lithic Clasts in NWA 7533

    NASA Astrophysics Data System (ADS)

    Sautter, V.; Wiens, R. C.; Toplis, M. J.; Cousin, A.; Forni, O.; Fabre, C.

    2014-12-01

    Curiosity rover landed at Gale, an early Hesperian age crater formed within Noachian rocks. In Hummocky plain, more than half of the igneous floats rocks are highly alkaline rocks (Stolper et al. doi: 101126/science.12239463, Schmidt et al. doi: 10.1002/2013JE004481) and feldspar-bearing rocks (Sautter et al. doi: 10.1002/2013JE00447). ChemCam observations at sub-millimeter scale show that these samples contain a significant feldspar component, either associated with LCP in gabbroic texture or with augite in effusive rocks defining an alkaline K-feldspar-bearing suite: basanite, trachy-andesite with porphyritic texture and syenitic rock with apahnitic texture. This series likely resulted from differentiation of liquids produced by low degrees of partial melting of primitive mantle. These rocks are float rocks or occurred as clast in conglomerate suggesting a provenance from Gale crater rim. NWA 7533 is the first Noachian breccia sampling the southern hemisphere Martian regolith. It is a polymict breccia with leucocratic clasts including zircon with 4.4 Ga ages Humayun et al., doi :10.1038/nature). The alkali basaltic evolved clasts contain two feldspars (alkali and plagioclase) and modal recombination gives a basaltic trachy-andesite, gabbroic, trachy-andesite and mugearite clast (Agee et al. doi: 10.1126/science. 1228858). Noritic clasts contain andesine, LCP, and Cr-magnetite. The monzonitic/mugearitic-evolved clasts are composed of alkali feldspar, plagioclase, augite, Ti-Magnetite, Cl-apatite and zircon. These clasts would represent products of Martian crust emplaced at 4.5 Ga and re-melted at 4.4 Ga (Humayun et al., doi :10.1038/nature). The leucocratic clasts of the Noachian SNC breccia will be compared with evolved lithology encountered at Gale crater and products of Noachian magmatism will be discussed.

  9. Contrasting methods of fracture trend characterization in crystalline metamorphic and igneous rocks of the Windham quadrangle, New Hampshire

    USGS Publications Warehouse

    Walsh, G.J.; Clark, S.F.

    2000-01-01

    The bedrock of the Windham quadrangle in southeastern New Hampshire consists of deformed early Palaeozoic crystalline metamorphic and intrusive igneous rocks intruded by Mesozoic igneous dikes. Generally, less common northeast striking, steeply dipping fractures developed sub-parallel to the pre-existing tectonic foliation in the Palaeozoic rocks. Mesozoic lamprophyre and diabase dikes intruded along the northeast trending fractures, utilizing the pre-existing anisotropy in the crystalline rocks. Northwest striking, steeply dipping systematic joints and joint sets are the most prominent fractures in the area and, at least in part, post-date the Mesozoic dikes. Sub-horizontal sheeting joints occur in all rock types. Locally, the coincidence of the sub-horizontal fractures with a sub-horizontal Paleozoic cleavage suggests that some of the sheeting fractures utilized the pre-existing ductile anisotropy during unloading. Generally, the metasedimentary rocks show a less complex pattern of fracturing than the intrusive rocks suggesting that rock type is a controlling factor. Metasedimentary rocks in the biotite zone and well-foliated igneous rocks show a greater tendency to fracture along pre-existing bedding and foliation surfaces than metasedimentary rocks in the garnet zone and poorly foliated igneous rocks. A comparison of mapped fracture data and station fracture data indicates that either mapped data or station data can be used to identify regional fracture trends. Local fracture trends can not be identified by limited measurements at a few fracture stations, however, because they do not address spatial variability. Some fracture trends may be scale-dependant because they may be either unique to a local area or present only at regional scales.

  10. Application of spatially weighted Technology for mapping intermediate and felsic igneous rocks in Fujian Province, China

    NASA Astrophysics Data System (ADS)

    Zhang, Daojun

    2016-04-01

    Magmatic activity is of great significance to mineralization not only for heat and fluid it provides, but also for parts of material source it brings. Due to the cover of soil and vegetation and its spatial nonuniformity detected singals from the ground's surface may be weak and of spatial variability, and this brings serious challenges to mineral exploration in these areas. Two models based on spatially weighted technology, i.e., local singularity analysis (LSA) and spatially weighted logistic regression (SWLR) are applied in this study to deal with this challenge. Coverage cannot block the migration of geochemical elements, it is possible that the geochemical features of soil above concealed rocks can be different from surrounding environment, although this kind of differences are weak; coverage may also weaken the surface expression of geophysical fields. LSA is sensitive to weak changes in density or energy, which makes it effective to map the distribution of concealed igneous rock based on geochemical and geophysical properties. Data integration can produce better classification results than any single data analysis, but spatial variability of spatial variables caused by non-stationary coverage can greatly affect the results since sometimes it is hard to establish a global model. In this paper, SWLR is used to integrate all spatial layers extracted from both geochemical and geophysical data, and the iron polymetallic metallogenic belt in sours-west of Fujian Province is used as s study case. It is found that LSA technique effectively extracts different sources of geologic anomalies; and the spatial distribution of intermediate and felsic igneous rocks delineated by SWLR shows higher accuracy compared with the result obtained via global model.

  11. Diffusion effects on oxygen isotope temperatures of slowly cooled igneous and metamorphic rocks

    NASA Astrophysics Data System (ADS)

    Giletti, Bruno J.

    1986-03-01

    Recently obtained data on oxygen diffusion in feldspars, quartz, and hornblende permit the prediction of the apparent 18O 16O temperatures that would be measured in a rock that consisted only of those three minerals, and cooled slowly from high temperature. The computed temperatures would be based on the differences in the 18O 16O ratios between coexisting pairs of minerals. The present calculation takes into account the diffusion rates for oxygen as a function of temperature, the cooling rate of the rock, the mineral grain sizes, and the mode of the rock. For mineral grains 1 mm in radius, and a cooling rate of 10°C/m.y., the minimum difference in apparent temperature between quartz-feldspar and feldspar-hornblende pairs will be 115°C, despite the assumption of a normal, uneventful, slow cooling history to room temperature. Further, the apparent quartz-hornblende temperature will range over 30°C (590-620°C) depending on the mode of the rock. For a cooling rate of 1000°C/m.y., the apparent difference in temperature can be as much as 400°C. Consequently, consistency in temperatures obtained by oxygen isotope analysis should not be expected in most high-grade metamorphic rocks or igneous rocks which are cooled slowly. Departures from the pattern of temperatures obtained in this model would imply a very rapid quench from high temperature, or a complex history for the rock. For some minerals, including hornblende, the relation between temperature and the equilibrium fractionation of oxygen isotopes between coexisting phases has been derived from observed relations in natural specimens. The choice of the specimens used for such calibrations needs to be re-evaluated in light of these findings. This may result in a change in the equilibrium equation constants. An example from the literature, the San Jose tonalite, Baja California, Mexico, was modelled and yields δ 18O concentrations in the minerals that correspond closely with the measured values. This suggests

  12. Unusual shape of pyrrhotite inclusions in scapolite of igneous rocks from the southernern Urals

    NASA Astrophysics Data System (ADS)

    Korinevsky, V. G.; Korinevsky, E. V.

    2016-12-01

    The unique igneous rock (scapolite-diopside gabbro) from the Ilmeny Mountains in the southern Urals is described. Gabbro fills a segment of dike 1.3 m thick that cuts through calcite-dolomite carbonatite. Medium-grain pyroxenite with scapolite that occurs at selvages gradually passes to scapolite-bearing gabbro in the central part of the dike. Scapolite crystals display surfaces of concurrent growth, which are evidence of their magmatic origin. Scapolite (Me 63-70%) contains numerous pyrrhotite inclusions as platelets 0.001 mm thick oriented parallel to the cleavage plane {100}. The calculated pyrrhotite formula is consistent with its stoichiometry (Fe1-xS). The morphology of the platelets (hexagonal sections) and their optical properties indicate a hexagonal symmetry of pyrrhotite. As follows from the insignificant difference between scapolite grains with and without pyrrhotite inclusions, scapolite and pyrrhotite should be regarded as products of synchronous magmatic melt crystallization.

  13. Evolution of KREEP - Further petrologic evidence. [igneous rocks from Apollo 15 site

    NASA Technical Reports Server (NTRS)

    Crawford, M. L.; Hollister, L. S.

    1977-01-01

    It is hypothesized that KREEP samples from the Apollo 15 site are igneous. To support the hypothesis, comparisons are made with other crystalline KREEP samples, especially 14310. It is noted that the low siderophile element content and lack of high pressure phenocrysts in the Apollo 15 KREEP may be indications of a slower rise of KREEP melt to the surface, when contrasted with sample 14310. Gravitational separation of Fe-Ni metal is proposed as a mechanism to account for the depletion of siderophile elements relative to the Si-rich component. It is further suggested that KREEP may be the parent of Apollo 12 and 15 basalts, as well as of granitic rocks, due to the liquid immiscibility occurring during the KREEP melt crystallization, and the subsequent independent evolution of the components.

  14. Rb-Sr ages of igneous rocks from the Apollo 14 mission and the age of the Fra Mauro formation.

    NASA Technical Reports Server (NTRS)

    Papanastassiou, D. A.; Wasserburg, G. J.

    1971-01-01

    Internal Rb-Sr isochrons were determined on four basaltic rocks and on a basaltic clast from a breccia from the Fra Mauro landing site. An internal isochron was determined for rock 12004 and yielded a value in agreement with previous results for basaltic rocks from the Apollo 12 site. The crystallization ages for Apollo 14 basalts are only 0.2 to 0.3 AE older than were found for mare basalts from the Sea of Tranquility. Assuming these leucocratic igneous rocks to be representative of the Fra Mauro site, it follows that there were major igneous processes active in these regions, and presumably throughout the highlands, at times only slightly preceding the periods at which the maria were last flooded.

  15. Relative contribution of Precambrian metamorphic rocks and Cretaceous-Tertiary igneous rocks to Oligocene and Holocene fluvial sands and the unroofing of a magmatic arc

    SciTech Connect

    Molinaroli, E.; Basu, A. )

    1991-03-01

    Oligocene and Holocene fluvial sands were deposited in small extensional basins in a magmatic arc in southwestern Montana under relatively humid and semi-arid conditions, respectively. The source rocks are roof-pendants and thrust-slices of Precambrian metamorphic rocks (PCM) and Cretaceous-Tertiary igneous rocks (KTI) that make up the arc. The authors have surveyed 143,607 heavy mineral grains (HMGs) in polished thin sections of 55 samples collected from adjacent but discrete geomorphologic units. In the Holocene sands, of 5440 HMGs 519 are garnets and of 97,667 HMGs 395 are zircons. In the Oligocene sandstones, of 6397 HMGs 998 are garnets, and of 45,940 HMGs 331 are zircons. Garnets are absent in the igneous rocks and zircons are extremely rare in the metamorphic rocks. Garnets ar estimated to be about 100 times as abundant in the metamorphic rocks as the zircons are in the igneous rocks. Mass balance calculations show that the proportion of PCM/(PCM+KTI) ranges from 0 to 21% in Oligocene sandstones, and from 3 to 76% in Holocene sands in different local units. However, the overall PCM/(PCM+KTI) proportions in the Holocene and the Oligocene sands in southwestern Montana are 19% and 18%, respectively. This suggests that the roof pendants, thrust slices, and magmatic arc rocks have been unroofed in constant proportions since the Oligocene although locally the proportions have been different.

  16. Prospecting for Diverse Igneous Rock Types on Mars: Pixl on "black Beauty" Nwa 7533

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Flannery, D.; Allwood, A.; Thompson, D. R.; Hodyss, R. P.; Clark, B. C.; Elam, W. T.; Hurowitz, J.

    2015-12-01

    In order to understand the evolution of the Martian crust and mantle, we need to acquire and analyze samples of igneous rocks other than the basaltic and ultramafic lithologies represented by the majority of Martian meteorites. Recent results from the Curiosity Rover demonstrate that diverse rock types exist in some Martian sedimentary environments in the form of conglomerate components or float, some of which shed light on the nature of early Martian crust (e.g., Sautter et al., 2015). We are developing investigation strategies for the in-situ instruments that will be flown on the Mars 2020 rover. These instruments will be used to inform the sampling campaigns required for future sample return missions. To achieve this, we applied PIXL (Planetary Instrument for X-ray Lithochemistry), an instrument for the Mars 2020 rover mission, to the meteorite NWA 7533. This meteorite is a pairing of NWA 7034, known informally as "Black Beauty", a new type of Martian meteorite that is broadly similar to the average composition of the Martian crust. This type of meteorite is essentially a 'conglomerate', with many diverse rock types, including mafic, feldspathic, and exotic rock fragments such as feldspar-ilmenite-phosphate clasts, as observed using higher-spatial resolution and higher sensitivity laboratory instruments (e.g., Agee et al., 2013; Humayun et al., 2014; Santos et al., 2015). Using PIXL, we analyzed a mm-scale cut and polished surface and applied algorithms developed by the PIXL team to semi-autonomously define and group regions containing similar lithological components (Thompson et al., 2015). PIXL data rapidly reveal distinctive zircon-bearing lithologies and feldspar-ilmenite-phosphate clasts similar to the detailed petrographic and mineralogical observations. Results suggest that PIXL readily identifies lithologies with minerals and elements (e.g., Rb and Sr) that are important for geochronology studies.

  17. Porosity and surface area evolution during weathering of two igneous rocks

    SciTech Connect

    Navarre-Sitchler, Alexis; Cole, David; Rother, Gernot; Jin, Lixin; Buss, Heather; Brantley, S. L.

    2013-01-01

    During weathering, rocks release nutrients and storewater vital for growth ofmicrobial and plant life. Thus, the growth of porosity as weathering advances into bedrock is a life-sustaining process for terrestrial ecosystems. Here, we use small-angle and ultra small-angle neutron scattering to show how porosity develops during initial weathering under tropical conditions of two igneous rock compositions, basaltic andesite and quartz diorite. The quartz diorite weathers spheroidally while the basaltic andesite does not. The weathering advance rates of the two systems also differ, perhaps due to this difference in mechanism, from 0.24 to 100 mm kyr1, respectively. The scattering data document how surfaces inside the feldspar-dominated rocks change as weathering advances into the protolith. In the unaltered rocks, neutrons scatter fromtwo types of featureswhose dimensions vary from6 nmto 40 lm: pores and bumps on pore grain surfaces. These features result in scattering data for both unaltered rocks that document multi-fractal behavior: scattering is best described by amass fractal dimension (Dm) and a surface fractal dimension (Ds) for features of length scales greater than and less than 1 lm, respectively. In the basaltic andesite, Dm is approximately 2.9 and Ds is approximately 2.7. The mechanism of solute transport during weathering of this rock is diffusion. Porosity and surface area increase from 1.5%to 8.5%and 3 to 23 m2 g1 respectively in a relatively consistent trend across themm-thick plagioclase reaction front. Across this front, both fractal dimensions decrease, consistentwith development of amoremonodisperse pore networkwith smoother pore surfaces. Both changes are consistent largely with increasing connectivity of pores without significant surface roughening, as expected for transport-limited weathering. In contrast, porosity and surface area increase from 1.3% to 9.5% and 1.5 to 13 m2 g1 respectively across a many cm-thick reaction front in the

  18. U-Pb zircon geochronology and evolution of some Adirondack meta-igneous rocks

    NASA Technical Reports Server (NTRS)

    Mclelland, J. M.

    1988-01-01

    An update was presented of the recent U-Pb isotope geochronology and models for evolution of some of the meta-igneous rocks of the Adirondacks, New York. Uranium-lead zircon data from charnockites and mangerites and on baddeleyite from anorthosite suggest that the emplacement of these rocks into a stable crust took place in the range 1160 to 1130 Ma. Granulite facies metamorphism was approximately 1050 Ma as indicated by metamorphic zircon and sphene ages of the anorthosite and by development of magmatitic alaskitic gneiss. The concentric isotherms that are observed in this area are due to later doming. However, an older contact metamorphic aureole associated with anorthosite intrusion is observed where wollastonite develops in metacarbonates. Zenoliths found in the anorthosite indicate a metamorphic event prior to anorthosite emplacement. The most probable mechanism for anorthosite genesis is thought to be ponding of gabbroic magmas at the Moho. The emplacement of the anorogenic anorthosite-mangerite-charnockite suite was apparently bracketed by compressional orogenies.

  19. Radioactive occurrences in veins and igneous and metamorphic rocks of New Mexico with annotated bibliography. [Over 600 citations

    SciTech Connect

    McLemore, V. T.

    1982-01-01

    From an extensive literature search and field examination of 96 nonsandstone radioactive occurrences, the author compiled an annotated bibliography of over 600 citations and a list of 327 radioactive occurrences in veins and igneous and metamorphic rocks of New Mexico. The citations are indexed by individual radioactive occurrence, geographic area, county, fluorspar deposits and occurrences, geochemical analyses, and geologic maps. In addition, the geology, mineralization, and uranium and thorium potential of 41 geographic areas in New Mexico containing known radioactive occurrences in veins and igneous and metamorphic rocks or that contain host rocks considered favorable for uranium or thorium mineralization are summarized. A list of aerial-radiometric, magnetic, hydrogeochemical, and stream-sediment survey reports is included.

  20. Thermal infrared (2.5-13.5-micron) spectroscopic remote sensing of igneous rock types on particulate planetary surfaces

    NASA Technical Reports Server (NTRS)

    Salisbury, John W.; Walter, Louis S.

    1989-01-01

    The compositional significance of outstanding spectral features in the reflectance spectra of particulate igneous rocks was investigated by analyzing directional reflectance spectra, obtained with an FTIR spectrophotometer at 2.17-13.5 microns, of a suite of well-characterized igneous rocks ground to fine particle size. It was found that, using spectral features associated with the principal Christiansen frequency and with a region of relative transparency between the Si-O stretching and bending bands, it is possible to identify general rock type using the Walter and Salisbury (1989) SCFM chemical index, SCFM, defined as SCFM = SiO2/(SiO2 + CaO + FeO + MgO). It is emphasized, however, that the appearance and the wavelength of these features may be affected by environmental factors.

  1. Thermobarometric studies on the Levack Gneisses: Footwall rocks to the Sudbury Igneous Complex

    NASA Technical Reports Server (NTRS)

    James, R. S.; Peredery, W.; Sweeny, J. M.

    1992-01-01

    Granulite and amphibolite facies gneisses and migmatites of the Levack Gneiss Complex occupy a zone up to 8 km wide around the northern part of the Sudbury Igneous Complex (SIC). Orthopyroxene- and garnet-bearing tonalitic and semipelitic assemblages of granulite facies grade occur within 3 km of the SIC together with lenses of mafic and pyroxenitic rock compositions normally represented by an amphibole +/- cpx-rich assemblage; amphibolite facies assemblages dominate elsewhere in this terrain. These 2.711-Ga gneisses were introduced by (1) the Cartier Granite Batholith during late Archaean to early Proterozoic time and (2) the SIC, at 1.85 Ga, which produced a contact aureole 1-1.5 km wide in which pyroxene hornfelses are common within 200-300 m of the contact. A suite of 12 samples including both the opx-gt and amphibole-rich rock compositions have been studied. Garnets in the semipelitic gneisses are variably replaced by a plg-bio assemblage. Thermobarometric calculations using a variety of barometers and thermometers reported in the literature suggest that the granulite facies assemblages formed at depths in the 21-28 km range (6-8 kbar). Textures and mineral chemistry in the garnet-bearing semipelitic rocks indicate that this terrain underwent a second metamorphic event during uplift to depth in the 5-11 km range (2-3 kbar) and at temperatures as low as 500-550 C. This latter event is distinct from thermal recrystallization caused by the emplacement of the SIC; it probably represents metamorphism attributable to intrusion of the Cartier Granite Batholith. These data allow two interpretations for the crustal uplift of the Levack Gneisses: (1) The gneisses were tectonically uplifted prior to the Sudbury Event (due to intrusion of the Cartier Batholith); or (2) the gneisses were raised to epizonal levels as a result of meteorite impact at 1.85 Ga.

  2. Microstructure, shear modulus and attenuation in igneous rocks approaching melting at seismic frequencies

    NASA Astrophysics Data System (ADS)

    Chien, S.; Redfern, S. A.

    2010-12-01

    Melt-related attenuation mechanisms, such as viscous flow and squirt processes, are of paramount importance in understanding high seismic wave attenuation in partially molten regions of the deep Earth. Strong temperature dependence of the anelastic quality factor, Q, is one obvious consequence of such mechanisms. Mineralogical composition, grain size, melt viscosity and microstructure (morphology and size of the inter-granular pores/micro-cracks), are important parameters for modeling attenuation mechanisms, and are control rock properties, particularly in the partially molten rocks. There have been many theoretical studies linking creep or viscosity models and laboratory experiments for partially molten rocks. However, experimental data on the relationship between temperature and attenuation remains. In this study, the shear modulus (G) and inverse quality factor (1/Q) of two igneous rocks (gabbro and basalt) were measured in the laboratory at temperatures approaching the melting point using the inverted forced torsion pendulum. Attenuation increases exponentially when shear modulus drops rapidly towards to melting temperature in both gabbro (1400 K) and basalt (1250 K). For measurements conducted using cyclic shear stresses at 1Hz, two attenuation relaxation peaks are found in gabbro at 1214 K and 1410 K, while only one attenuation relaxation peak occurs in basalt at 1151 K. These attenuation peaks may result from grain boundary sliding, diffusion creep and/or melt squirt. In addition to the relaxation peaks, there is a rising exponential increase in attenuation approaching the melting point from below. A power law model has been used to determine the effective activation energy associated with this high-temperature attenuation background. An activation energy of 68 kJ/mole in basalt and 882 kJ/mole in gabbro is found. The result for gabbro is in a good agreement with the study of Fontaine et al. in 2005 (873 kJ/mol), and the very different behaviour of basalt

  3. Establishment of an empirical correlation for estimating the thermal conductivity of igneous rocks

    SciTech Connect

    Garcia, A.; Contreras, E. ); Viggiano, J.C. )

    1989-09-01

    A correlation to predict the thermal conductivity of andesitic igneous rocks is developed from measured data on drill cores from wells from the Los Azufres geothermal field, Mexico. The correlation was developed from density, porosity, and thermal conductivity. Seventeen determinations were made on drill cores extracted at varying depths from 12 wells. Thermal conductivity varied from 1.05 to 2.34 W {center dot} m{sup {minus}1} {center dot} K{sup {minus}1}, while bulk density varied from 2,050 to 2,740 kg {center dot} m{sup {minus}3} and grain density varied from 2,610 to 2,940 kg {center dot} m{sup {minus}3}. Total porosity varied from 1.9 to 24.7%. Two polynomial regressions, one linear and one quadratic, were tested on the thermal conductivity-times-bulk density product, with total porosity as the independent variable. The correlation coefficients and residual mean square deviations were 0.83 and 0.00491 for the linear fit and 0.87 and 0.00425 for the quadratic model, respectively. For porosities up to about 18%, both models showed very close predictions, but for larger values, the quadratic model appeared to be better and it is recommended for the porosity range from 0 to 25%. Furthermore, density and porosity may be determined from drill cuttings, which are more readily available than cores.

  4. Igneous petrogenesis and tectonic setting of granitic rocks from the eastern Blue Ridge, Alabama Appalachians

    SciTech Connect

    Drummond, M.S. . Geology Dept.); Allison, D.T. . Geology Dept.); Tull, J.F. . Geology Dept.); Bieler, D.B. . Geology Dept.)

    1994-03-01

    A span of 150 my of orogenic activity is recorded within the granitic rocks of the eastern Blue Ridge of Alabama (EBR). Four discrete episodes of plutonism can be differentiated, each event exhibiting distinct field relations and geochemical signatures. (1) Penobscotian stage: this initial stage of plutonic activity is represented by the Elkahatchee Quartz Diorite (EQD), a premetamorphic (495 Ma) batholith and the largest intrusive complex (880 km[sup 2]) exposed in the Blue Ridge. Calc-alkaline I-type tonalite-granodiorite are the principal lithologies, with subordinate cumulate hbl-bt diorite, metadacite, granite and trondhjemite. The parental tonalitic magmas are interpreted to have been derived from a subducted MORB source under eclogite to get amphibolite conditions. (2) Taconic stage: the Kowaliga augen gneiss (KAG) and the Zana granite gneiss (ZG) are 460 Ma granitic bodies that reside in the SE extremity and structurally highest portion of the EBR. Both of these bodies are pre-metamorphic with strongly elongate sill- and pod-like shapes concordant with S[sub 1] foliation. Granite and granodiorite comprise the bulk of the KAG. (3) Acadian stage: Rockford Granite (RG), Bluff springs Granite (BSG, 366 Ma), and Almond Trondhjemite represent a suite of pre- to syn-metamorphic granitic intrusions. (4) late-Acadian stage: The Blakes Ferry pluton (BFP) is a post-kinematic pluton displaying spectacular by schlieren igneous flow structures, but no metamorphic fabric. The pluton's age can be bracketed between a 366 Ma age on the BSG and a 324 Ma K-Ar muscovite age on the BFP. BFP's petrogenesis has involved partial melting a MORB source followed by assimilation of metasedimentary host rock.

  5. Flexure and faulting of sedimentary host rocks during growth of igneous domes, Henry Mountains, Utah

    USGS Publications Warehouse

    Jackson, M.D.; Pollard, D.D.

    1990-01-01

    A sequence of sedimentary rocks about 4 km thick was bent, stretched and uplifted during the growth of three igneous domes in the southern Henry Mountains. Mount Holmes, Mount Ellsworth and Mount Hillers are all about 12 km in diameter, but the amplitudes of their domes are about 1.2, 1.85 and 3.0 km, respectively. These mountains record successive stages in the inflation of near-surface diorite intrusions that are probably laccolithic in origin. The host rocks deformed along networks of outcrop-scale faults, or deformation bands, marked by crushed grains, consolidation of the porous sandstone and small displacements of sedimentary beds. Zones of deformation bands oriented parallel to the beds and formation contacts subdivided the overburden into thin mechanical layers that slipped over one another during doming. Measurements of outcrop-scale fault populations at the three mountains reveal a network of faults that strikes at high angles to sedimentary beds which themselves strike tangentially about the domes. These faults have normal and reverse components of slip that accommodated bending and stretching strains within the strata. An early stage of this deformation is displayed at Mount Holmes, where states of stress computed from three fault samples correlate with the theoretical distribution of stresses resulting from bending of thin, circular, elastic plates. Field observations and analysis of frictional driving stresses acting on horizontal planes above an opening-mode dislocation, as well as the paleostress analysis of faulting, indicate that bedding-plane slip and layer flexure were important components of the early deformation. As the amplitude of doming increased, radial and circumferential stretching of the strata and rotation of the older faults in the steepening limbs of the domes increased the complexity of the fault patterns. Steeply-dipping, map-scale faults with dip-slip displacements indicate a late-stage jostling of major blocks over the central

  6. Methylomonas scandinavica sp. nov., a new methanotrophic psychrotrophic bacterium isolated from deep igneous rock ground water of Sweden.

    PubMed

    Kalyuzhnaya, M G; Khmelenina, V N; Kotelnikova, S; Holmquist, L; Pedersen, K; Trotsenko, Y A

    1999-12-01

    Methane-utilizing bacteria were enriched from deep igneous rock environments and affiliated by amplification of functional and phylogenetic gene probes. Type I methanotrophs belonging to the genera Methylomonas and Methylobacter dominated in enrichment cultures from depths below 400 m. A pure culture of an obligate methanotroph (strain SR5) was isolated and characterized. Pink-pigmented motile rods of the new isolate contained intracytoplasmic membranes as stacks of vesicles, assimilated methane via the ribulose monophosphate pathway and had an incomplete tricarboxylic acid cycle. Phosphatidyl glycerol, methylene ubiquinone and cytochrome c552 were prevailing. The DNA G+C content is 53.3 mol %. Strain SR5 grew at temperatures between 5 and 30 degrees C with optimum at 15 degrees C, close to its in situ temperature. Analyses of 16S rRNA gene, whole cell protein, enzymatic and physiological analyses of strain SR-5 revealed significant differences compared to the other representatives of Type I methanotrophs. Based on pheno- and genotypic characteristics we propose to refer the strain SR5 as to a new species, Methylomonas scandinavica.

  7. Igneous phosphate rock solubilization by biofilm-forming mycorrhizobacteria and hyphobacteria associated with Rhizoglomus irregulare DAOM 197198.

    PubMed

    Taktek, Salma; St-Arnaud, Marc; Piché, Yves; Fortin, J André; Antoun, Hani

    2017-01-01

    Biofilm formation on abiotic and biotic surfaces was studied with two hyphobacteria, strongly attached to the surface of the arbuscular mycorrhizal fungus (AMF) Rhizoglomus irregulare (Ri) DAOM 197198 and two mycorrhizobacteria, loosely attached to the roots of different mycorrhizal plants. When the sparingly soluble igneous phosphate rock (PR) from Quebec, or when the chemical hydroxyapatite were used as sole phosphorus (P) source, hyphobacteria Rhizobium miluonense Rm3 and Burkholderia anthina Ba8 produced significantly more biofilms than mycorrhizobacteria Rahnella sp. Rs11 and Burkholderia phenazinium Bph12, as indicated by the crystal violet assay or by quantifying biofilm exopolysaccharides. As previously observed with planktonic bacteria, biofilms mobilized P by lowering the pH and releasing gluconic acid. The high efficiency of P mobilization by the hyphobacteria Ba8 was linked to the presence of more viable cells in its biofilm as revealed by the hydrolysis of fluorescein diacetate. Scanning electron microscopy micrographs showed a high adherence of the best P-solubilizer hyphobacteria Ba8 on the surface of Quebec PR. Hydroxyapatite porous structure did not allow a good adherence of Ba8. Ba8 formed an important biofilm on the hyphae of Ri DAOM 197198 with low reactive Quebec PR while no biofilm was observed with the high reactive hydroxyapatite. Results confirm the possible presence of specificity between the Ri DAOM 197198 and the hyphobacteria and suggest that the interaction would be regulated by the availability of P.

  8. PHASS99: A software program for retrieving and decoding the radiometric ages of igneous rocks from the international database IGBADAT

    NASA Astrophysics Data System (ADS)

    Al-Mishwat, Ali T.

    2016-05-01

    PHASS99 is a FORTRAN program designed to retrieve and decode radiometric and other physical age information of igneous rocks contained in the international database IGBADAT (Igneous Base Data File). In the database, ages are stored in a proprietary format using mnemonic representations. The program can handle up to 99 ages in an igneous rock specimen and caters to forty radiometric age systems. The radiometric age alphanumeric strings assigned to each specimen description in the database consist of four components: the numeric age and its exponential modifier, a four-character mnemonic method identification, a two-character mnemonic name of analysed material, and the reference number in the rock group bibliography vector. For each specimen, the program searches for radiometric age strings, extracts them, parses them, decodes the different age components, and converts them to high-level English equivalents. IGBADAT and similarly-structured files are used for input. The output includes three files: a flat raw ASCII text file containing retrieved radiometric age information, a generic spreadsheet-compatible file for data import to spreadsheets, and an error file. PHASS99 builds on the old program TSTPHA (Test Physical Age) decoder program and expands greatly its capabilities. PHASS99 is simple, user friendly, fast, efficient, and does not require users to have knowledge of programing.

  9. Pliocene-Pleistocene diatoms in Paleozoic and Mesozoic sedimentary and igneous rocks from Antarctica: A Sirius problem solved

    NASA Astrophysics Data System (ADS)

    Burckle, Lloyd H.; Potter, Noel, Jr.

    1996-03-01

    There are two competing scenarios on the behavior of the East Antarctic ice sheet during the late Tertiary. In one scenario, the ice sheet was very dynamic and underwent major drawdown and renewal as late as the Pliocene. In the other, the ice sheet was relatively stable during the late Neogene. The presence of marine diatoms in Sirius Group sedimentary rocks in East Antarctica is at the center of the disagreement. One side regards the diatoms as the major piece of evidence to support the drawdown and renewal hypothesis and infers that they were introduced into the Sirius during renewed glaciation of East Antarctica; others suggest that these diatoms were likely introduced into the Sirius by atmospheric (largely eolian) processes. We propose a simple test of the eolian hypothesis. If diatoms were introduced into the Sirius by eolian processes, then they should also be present in older (Paleozoic and Mesozoic) sedimentary and igneous rocks. Samples from two units of the Beacon Supergroup (Devonian to Jurassic) from Beacon Valley, East Antarctica, were analyzed: the Beacon Heights Orthoquartzite (Devonian) and the Feather Conglomerate (Permian-Triassic). Also examined was sediment found in cracks of Paleozoic and Mesozoic (Devonian to Cretaceous) igneous rocks from Marie Byrd Land, West Antarctica. Largely Pliocene-Pleistocene planktonic marine diatoms were found in all sample sets. Because neither Beacon Supergroup sedimentary rocks nor igneous rocks from Marie Byrd Land are Pliocene-Pleistocene in age, such findings strongly suggest that diatoms were introduced into them by eolian processes. This same scenario can be applied to Sirius Group sedimentary rocks.

  10. Geochemistry and petrogenesis of anorogenic basic volcanic-plutonic rocks of the Kundal area, Malani Igneous Suite, western Rajasthan, India

    NASA Astrophysics Data System (ADS)

    Krishnakanta Singh, A.; Vallinayagam, G.

    2004-12-01

    The Kundal area of Malani Igneous Suite consists of volcano-plutonic rocks. Basalt flows and gabbro intrusives are associated with rhyolite. Both the basic rocks consist of similar mineralogy of plagioclase, clinopyroxene as essential and Fe-Ti oxides as accessories. Basalt displays sub-ophitic and glomeroporphyritic textures whereas gabbro exhibits sub-ophitic, porphyritic and intergrannular textures. They show comparable chemistry and are enriched in Fe, Ti and incompatible elements as compared to MORB/CFB. Samples are enriched in LREE and slightly depleted HREE patterns with least significant positive Eu anomalies. Petrographical study and petrogenetic modeling of [Mg]-[Fe], trace and REE suggest cogenetic origin of these basic rocks and they probably derived from Fe-enriched source with higher Fe/Mg ratio than primitive mantle source. Thus, it is concluded that the basic volcano-plutonic rocks of Kundal area are the result of a low to moderate degree (< 30%) partial melting of source similar to picrite/komatiitic composition. Within plate, anorogenic setting for the basic rocks of Kundal area is suggested, which is in conformity with the similar setting for Malani Igneous Suite.

  11. End-to-End Models for Effects of System Noise on LIMS Analysis of Igneous Rocks

    SciTech Connect

    Clegg, Samuel M; Bender, Steven; Wiens, R. C.; Carmosino, Marco L; Speicher, Elly A; Dyar, M. D.

    2010-12-23

    The ChemCam instrument on the Mars Science Laboratory will be the first extraterrestial deployment of laser-induced breakdown spectroscopy (UBS) for remote geochemical analysis. LIBS instruments are also being proposed for future NASA missions. In quantitative LIBS applications using multivariate analysis techniques, it is essential to understand the effects of key instrument parameters and their variability on the elemental predictions. Baseline experiments were run on a laboratory instrument in conditions reproducing ChemCam performance on Mars. These experiments employed Nd:YAG laser producing 17 mJ/pulse on target and an with a 200 {micro}m FWHM spot size on the surface of a sample. The emission is collected by a telescope, imaged on a fiber optic and then interfaced to a demultiplexer capable of >40% transmission into each spectrometer. We report here on an integrated end-to-end system performance model that simulates the effects of output signal degradation that might result from the input signal chain and the impact on multivariate model predictions. There are two approaches to modifying signal to noise (SNR): degrade the signal and/or increase the noise. Ishibashi used a much smaller data set to show that the addition of noise had significant impact while degradation of spectral resolution had much less impact on accuracy and precision. Here, we specifically focus on aspects of remote LIBS instrument performance as they relate to various types of signal degradation. To assess the sensitivity of LIBS analysis to signal-to-noise ratio (SNR) and spectral resolution, the signal in each spectrum from a suite of 50 laboratory spectra of igneous rocks was variably degraded by increasing the peak widths (simulating misalignment) and decreasing the spectral amplitude (simulating decreases in SNR).

  12. Plagioclase preferred orientation and induced seismic anisotropy in mafic igneous rocks

    NASA Astrophysics Data System (ADS)

    Ji, Shaocheng; Shao, Tongbin; Salisbury, Matthew H.; Sun, Shengsi; Michibayashi, Katsuyoshi; Zhao, Weihua; Long, Changxing; Liang, Fenghua; Satsukawa, Takako

    2014-11-01

    Fractional crystallization and crystal segregation controlled by settling or floating of minerals during the cooling of magma can lead to layered structures in mafic and ultramafic intrusions in continental and oceanic settings in the lower crust. Thus, the seismic properties and fabrics of layered intrusions must be calibrated to gain insight into the origin of seismic reflections and anisotropy in the deep crust. To this end, we have measured P and S wave velocities and anisotropy in 17 plagioclase-rich mafic igneous rocks such as anorthosite and gabbro at hydrostatic pressures up to 650 MPa. Anorthosites and gabbroic anorthosites containing >80 vol% plagioclase and gabbros consisting of nearly equal modal contents of plagioclase and pyroxene display distinctive seismic anisotropy patterns: Vp(Z)/Vp(Y) ≥ 1 and Vp(Z)/Vp(X) ≥ 1 for anorthosites while 0.8 < Vp(Z)/Vp(Y) ≤ 1 and 0.8 < Vp(Z)/Vp(X) ≤ 1 for gabbros. Amphibolites lie in the same domain as gabbros, but show a significantly stronger tendency of Vp(X) > Vp(Y) than the gabbros. Laminated anorthosites with Vp(X) ≈ Vp(Y) ≪ Vp(Z) display a strong crystal preferred orientation (CPO) of plagioclase whose (010) planes and [100] and [001] directions parallel to the foliation. For the gabbros and amphibolites characterized by Vp(X) ≈ Vp(Y) > Vp(Z) and Vp(X) > Vp(Y) > Vp(Z), respectively, pyroxene and amphibole play a dominant role over plagioclase in the formation of seismic anisotropy. The Poisson's ratio calculated using the average P and S wave velocities from the three principal propagation-polarization directions (X, Y, and Z) of a highly anisotropic anorthosite cannot represent the value of a true isotropic equivalent. The CPO-induced anisotropy enhances and decreases the foliation-normal incidence reflectivity at gabbro-peridotite and anorthosite-peridotite interfaces, respectively.

  13. Variations in the Pb isotope composition in polyformational magmatic rocks of the Ketkap-Yuna igneous province of the Aldan Shield: Evidence for mantle-crust interaction

    NASA Astrophysics Data System (ADS)

    Polin, V. F.; Dril, S. I.; Khanchuk, A. I.; Velivetskaya, T. A.; Vladimirova, T. A.; Il'ina, N. N.

    2016-06-01

    The Pb isotope composition of polyformational Mesozoic igneous rocks of the Ketkap-Yuna igneous province (KYIP) and lower crustal metamorphic rocks of the Batomga granite-greenstone area (the complex of the KYIP basement) of the Aldan Shield was studied for the first time. Based on the data obtained, several types of material sources participating in petrogenetic processes were distinguished. The mantle source identified as PREMA is registered in most of the igneous formations and predominates in mafic alkaline rocks. According to the isotope characteristics, the upper crustal source corresponds to a source of the "Orogen" type by the model of "plumbotectonics" or to the average composition of the continental crust by the Stacey-Kramers model. The lower crust is the third material source; however, the type of lower crustal protolith involved in the igneous process is still not defined, which makes difficult to estimate its role in the petrogenetic processes.

  14. Distribution and origin of igneous rocks from the landward slopes of the Mariana Trench: Implications for its structure and evolution

    SciTech Connect

    Bloomer, S.H.

    1983-09-10

    The landward slope of the Mariana Trench is composed largely of igneous rocks. Serpentinites and serpentinized ultramafic rocks occur at nearly all structural levels on the slope from depths of 8000 to 1200 m. Seamountlike features on the trench slope break are the surface expression of serpentinite diapirs. Cumulate and massive gabbros are found; several varieties of volcanic rocks are common including boninites, altered and metamorphosed basalts, andesites, and dacites. The chemical characteristics of the volcanic rocks indicate that nearly all are products of island arc volcanism. Together with the gabbros, these volcanic rocks represent what is probably a late Eocene arc complex. These rocks were probably the first volcanic products to result from the subduction of the Pacific plate beneath the Phillippine Sea plate; their exposure on the trench slope today implies a significant amount of tectonic erosion of the landward slope since Eocene time. Most of this removal of material appears to have occurred during the early stages of subduction. There are isolated occurrences on the landward slope of rock assemblages including alkalic basalts, chert, hyaloclastites, upper Cretaceous siliceous sediments, and shallow water limestones. These assemblages are very similar to rocks dredged from seamounts on the offshore flank of the trench, and their presence on the landward slope suggests that since the cessation of vigorous tectonic erosion, there has been episodic accretion of seamount fragments to the landward slope.

  15. Middle Jurassic oceanic island igneous rocks of the Raohe accretionary complex, northeastern China: Petrogenesis and tectonic implications

    NASA Astrophysics Data System (ADS)

    Wang, Zhi-Hui; Ge, Wen-Chun; Yang, Hao; Zhang, Yan-Long; Bi, Jun-Hui; Tian, De-Xin; Xu, Wen-Liang

    2015-11-01

    Whole-rock major and trace element, and Sr, Nd, and Hf isotopic data, together with zircon U-Pb ages and in situ zircon Hf isotopes, are reported for Middle Jurassic igneous rocks of the Raohe accretionary complex, northeastern China, to investigate their petrogenesis and tectonic implications. The igneous rocks consist of pillow basalt, pyroxenite, gabbro, plagioclasite, and plagiogranite. The zircons from one plagioclasite and one plagiogranite are euhedral-subhedral and display fine-scale oscillatory growth zoning, indicating a magmatic origin. Zircon U-Pb dating gives an emplacement age of 169-167 Ma. The basalts are associated with late Paleozoic to middle Mesozoic sediments typical of ocean plate stratigraphy; i.e., limestone, bedded chert, and siliceous shale. The basalts, which show geochemical features similar to those of oceanic island basalts (OIBs), are enriched in TiO2, light rare earth elements (LREEs) (average: La/Smn = 2.12), and Nb (average: Zr/Nb = 12.24), and are characterized by positive Nb anomalies (averages: Nb/Thpm = 1.46, Nb/Lapm = 1.31). The rocks are depleted in heavy rare earth elements (HREEs) (average: Gd/Ybn = 2.03) and exhibit high εNd(t) (+8.2 to +8.3) and εHf(t) (+9.0 to +9.1) values. The geochemical features indicate the Jurassic OIB-like basalts were derived by a low degree of partial melting (<5%) of peridotite in the garnet stability field. The intermediate-mafic intrusive rocks show typical OIB affinities and are geochemically similar to the basalts. Most of the intermediate-mafic intrusive rocks are enriched in LREEs and Nb, depleted in HREEs, and show low Zr/Nb ratios and high εNd(t) (+7.2 to +8.2) and εHf(t) (+8.8 to +10.3) values, indicating they were derived from a common source and are the products of fractional crystallization of the OIB-like basalts. All of the igneous rocks are likely fragments of oceanic islands/seamounts. The identification of OIB-like basalts and associated intermediate-mafic intrusive rocks

  16. An introduction to the application of X-ray microtomography to the three-dimensional study of igneous rocks

    NASA Astrophysics Data System (ADS)

    Baker, D. R.; Mancini, L.; Polacci, M.; Higgins, M. D.; Gualda, G. A. R.; Hill, R. J.; Rivers, M. L.

    2012-09-01

    Imaging rocks in three-dimensions through X-ray microtomography enables routine visualization of structures in samples, which can be spatially resolved down to the sub-micron scale. Although X-ray tomography has been applied in biomedical research and clinical settings for decades, it has only recently been applied to studies of rocks, and few geoscientists realize its value and potential. This contribution provides an introduction to the principles and techniques of X-ray microtomography to the study of igneous rock textures as well as reviewing the current state of the art. We hope that this short review will encourage more geoscientists to apply X-ray microtomography in their research and that this will lead to new insights into the processes that occur in magmatic (as well as other geological) systems.

  17. An introduction to the application of X-ray microtomography to the three-dimensional study of igneous rocks

    SciTech Connect

    Baker, D.R.; Mancini, L.; Polacci, M.; Higgins, M.D.; Gualda, G.A.R.; Hill, R.J.; Rivers, M.L.

    2012-10-25

    Imaging rocks in three-dimensions through X-ray microtomography enables routine visualization of structures in samples, which can be spatially resolved down to the sub-micron scale. Although X-ray tomography has been applied in biomedical research and clinical settings for decades, it has only recently been applied to studies of rocks, and few geoscientists realize its value and potential. This contribution provides an introduction to the principles and techniques of X-ray microtomography to the study of igneous rock textures as well as reviewing the current state of the art. We hope that this short review will encourage more geoscientists to apply X-ray microtomography in their research and that this will lead to new insights into the processes that occur in magmatic (as well as other geological) systems.

  18. Chemical weathering on Mars - Thermodynamic stabilities of primary minerals /and their alteration products/ from mafic igneous rocks

    NASA Technical Reports Server (NTRS)

    Gooding, J. L.

    1978-01-01

    Chemical weathering on Mars is examined theoretically from the standpoint of thermodynamic equilibrium between primary rock-forming minerals and the atmospheric gases O2, H2O, and CO2. The primary minerals considered are those common to mafic igneous rocks and include olivine, pyroxene, plagioclase, magnetite, troilite, pyrrhotite, and apatite. The importance of kinetics and reaction mechanisms in controlling possible weathering processes on Mars is discussed within the limits of currently available data, and the possible influence of liquid water on Martian weathering processes is evaluated where appropriate. For gas-solid weathering of mafic igneous rocks at the Martian surface, it is concluded that upon attainment of thermodynamic equilibrium: (1) oxides and carbonates should dominate the mineral assemblage of weathering products; (2) hematite rather than goethite should be the stable mineral form of Fe (III); (3) FeSO4 or FeSO4.H2O could be the stable weathering product of iron sulfides in the absence of liquid water; and (4) kaolinite is apparently the only clay mineral that should be thermodynamically stable over all ranges of temperature and water-vapor abundance at the Martian surface.

  19. Multistage amphiboles from the Galinge iron skarn deposit in Qiman Tagh, western China: evidence of igneous rocks replacement

    NASA Astrophysics Data System (ADS)

    Yu, M.; Feng, C.-Y.; Zhu, Y.-F.; Mao, J.-W.; Zhao, Y.-M.; Li, D.-X.

    2017-02-01

    Amphiboles from the Galinge skarn deposit, the largest iron (Fe) polymetallic skarn deposit in the Qiman Tagh metallogenic belt (western China), were formed by multistage fluid-rock interactions. Mineral analysis of the various amphiboles suggest that they were formed by the replacement of mafic to intermediate igneous rocks. The two alteration phases have formed three generations of compositionally distinct amphiboles: Amp-I: Ferro-edenitic hornblende (FE); Amp-II: Deep bluish-green magnesian-hastingsite (MH); Amp-III: Light greenish-beige ferro-actinolite (FA). The Amp-I preserves the primary igneous amphibole composition, and was subsequently replaced by Amp-II. The amphibole Cl content markedly increases from the FE (0.176 - 0.582 wt.%) to the MH (0.894 - 3.161 wt.%), and abruptly drops in the FA (0.017 - 0.039 wt.%). The Cl-rich MH contains the lowest concentration of Si [5.64 - 6.28 atoms per formula unit (apfu)], and the highest (K + Na) values (0.72 - 1.06 apfu) in the amphibole A-site with a high K/(K + Na) of 0.491 to 0.429. Both Mg and Fe contents of the MH and FA vary widely, possibly due to the interactions of magma-derived hydrothermal fluids with the basaltic / andesitic host rocks.

  20. Geology and porphyry copper-type alteration-mineralization of igneous rocks at the Christmas Mine, Gila County, Arizona

    USGS Publications Warehouse

    Koski, Randolph A.

    1979-01-01

    The Christmas copper deposit, located in southern Gila County, Arizona, is part of the major porphyry copper province of southwestern North America. Although Christmas is known for skarn deposits in Paleozoic carbonate rocks, ore-grade porphyry-type copper mineralization also occurs in a composite granodioritic intrusive complex and adjacent mafic volcanic country rocks. This study considers the nature, distribution, and genesis of alteration-mineralization in the igneous rock environment at Christmas. At the southeast end of the Dripping Spring Mountains, the Pennsylvanian Naco Limestone is unconformably overlain by the Cretaceous Williamson Canyon Volcanics, a westward-thinning sequence of basaltic volcanic breccia and lava flows, and subordinate clastic sedimentary rocks. Paleozoic and Mesozoic strata are intruded by Laramide-age dikes, sills, and small stocks of hornblende andesite porphyry and hornblende rhyodacite porphyry, and the mineralized Christmas intrusive complex. Rocks of the elongate Christmas stock, intruded along an east-northeast-trending fracture zone, are grouped into early, veined quartz diorite (Dark Phase), biotite granodiorite porphyry (Light Phase), and granodiorite; and late, unveined dacite porphyry and granodiorite porphyry. Biotite rhyodacite porphyry dikes extending east and west from the vicinity of the stock are probably coeval with biotite granodiorite porphyry. Accumulated normal displacement of approximately 1 km along the northwest-trending Christmas-Joker fault system has juxtaposed contrasting levels (lower, intrusive-carbonate rock environment and upper, intrusive-volcanic rock environment) within the porphyry copper system. K-Ar age determinations and whole-rock chemical analyses of the major intrusive rock types indicate that Laramide calc-alkaline magmatism and ore deposition at Christmas evolved over an extended period from within the Late Cretaceous (~75-80 m.y. ago) to early Paleocene (~63-61 m.y. ago). The sequence of

  1. The superior analyses of igneous rocks from Roth's Tabellen, 1869 to 1884, arranged according to the quantitative system of classification

    USGS Publications Warehouse

    Washington, H.S.

    1904-01-01

    In Professional Paper No. 14 there were collected the chemical analyses of igneous rocks published from 1884 to 1900, inclusive, arranged according to the quantitative system of classification recently proposed by Cross, Iddings, Pirsson, and Washington. In order to supplement this work it has appeared advisable to select the more reliable and complete of the earlier analyses collected by Justus Roth and arrange them also in the same manner for publication. Petrographers would thus have available for use according to the new system almost the entire body of chemical work of real value on igneous rocks, the exceptions being a few analyses published prior to 1900 which may have been overlooked by both Roth and myself. The two collections would form a foundation as broad as possible for future research and discussion. I must express my sense of obligation to the United States Geological Survey for publishing the present collection of analyses, and my thanks to my colleagues in the new system of classification for their friendly advice and assistance. 

  2. Multistage amphiboles from the Galinge iron skarn deposit in Qiman Tagh, western China: evidence of igneous rocks replacement

    NASA Astrophysics Data System (ADS)

    Yu, M.; Feng, C.-Y.; Zhu, Y.-F.; Mao, J.-W.; Zhao, Y.-M.; Li, D.-X.

    2016-08-01

    Amphiboles from the Galinge skarn deposit, the largest iron (Fe) polymetallic skarn deposit in the Qiman Tagh metallogenic belt (western China), were formed by multistage fluid-rock interactions. Mineral analysis of the various amphiboles suggest that they were formed by the replacement of mafic to intermediate igneous rocks. The two alteration phases have formed three generations of compositionally distinct amphiboles: Amp-I: Ferro-edenitic hornblende (FE); Amp-II: Deep bluish-green magnesian-hastingsite (MH); Amp-III: Light greenish-beige ferro-actinolite (FA). The Amp-I preserves the primary igneous amphibole composition, and was subsequently replaced by Amp-II. The amphibole Cl content markedly increases from the FE (0.176 - 0.582 wt.%) to the MH (0.894 - 3.161 wt.%), and abruptly drops in the FA (0.017 - 0.039 wt.%). The Cl-rich MH contains the lowest concentration of Si [5.64 - 6.28 atoms per formula unit (apfu)], and the highest (K + Na) values (0.72 - 1.06 apfu) in the amphibole A-site with a high K/(K + Na) of 0.491 to 0.429. Both Mg and Fe contents of the MH and FA vary widely, possibly due to the interactions of magma-derived hydrothermal fluids with the basaltic / andesitic host rocks. Formation of the Cl-rich MH may have been associated with the early high-temperature and high-saline hydrothermal fluids, meanwhile the Cl-poor FA may have formed from later low-temperature and low-saline hydrothermal fluids. The MH plays an important role for consuming Cl carried by hydrothermal fluids. The Cl-rich fluids may have mobilized some elements, such as Fe, Al, Mg, Ca and Ti from the host rocks. Considerable amounts of Ti, Al, Mg and Fe were incorporated into the sphene and Fe-Ti oxides that coexist with the MH.

  3. Geochronology of igneous rocks and formation of the Late Paleozoic south Mongolian active margin of the Siberian continent

    NASA Astrophysics Data System (ADS)

    Yarmolyuk, V. V.; Kovalenko, V. I.; Sal'Nikova, E. B.; Kovach, V. P.; Kozlovsky, A. M.; Kotov, A. B.; Lebedev, V. I.

    2008-04-01

    The succession of magmatic events associated with development of the Early Carboniferous-Early Permian marginal continental magmatic belt of southern Mongolia is studied. In the belt structure there are defined the successive rock complexes: the older one represented by differentiated basalt-andesite-rhyodacite series and younger bimodal complex of basalt-comendite-trachyrhyolite composition. The granodiorite-plagiogranite and banatite (diorite-monzonite-granodiorite) plutonic massifs are associated with the former, while peralkaline granite massifs are characteristic of the latter. First systematic geochronological study of igneous rock associations is performed to establish time succession and structural position of both complexes. Geochronological results and geological relations between rocks of the bimodal and differentiated complexes showed first that rocks of the differentiated complex originated 350 to 330 Ma ago at the initial stage of development of the marginal continental belt. This is evident from geochronological dates obtained for the Adzh-Bogd and Edrengiyn-Nuruu massifs and for volcanic associations of the complex. The dates are consistent with paleontological data. The bimodal association was formed later, 320 to 290 Ma ago. The time span separating formation of two igneous complexes ranges from several to 20 30 m.y. in different areas of the marginal belt. The bimodal magmatism was interrelated with rifting responsible for development of the Gobi-Tien Shan rift zone in the belt axial part and the Main Mongolian lineament along the belt northern boundary. Loci of bimodal rift magmatism likely migrated with time: the respective magmatic activity first initiated on the west of the rift system and then advanced gradually eastward with development of rift structures. Normal granitoids untypical but occurring nevertheless among the products of rift magmatism in addition to peralkaline massifs are assumed to have been formed, when the basic magmatism

  4. Isotopic ages for alkaline igneous rocks, including a 26 Ma ignimbrite, from the Peshawar plain of northern Pakistan and their tectonic implications

    NASA Astrophysics Data System (ADS)

    Ahmad, Irshad; Khan, Shuhab; Lapen, Thomas; Burke, Kevin; Jehan, Noor

    2013-01-01

    New isotopic ages on zircons from rocks of the Peshawar Plain Alkaline Igneous Province (PPAIP) reveal for the first time the occurrence of ignimbritic Cenozoic (Oligocene) volcanism in the Himalaya at 26.7 ± 0.8 Ma. Other new ages confirm that PPAIP rift-related igneous activity was Permian and lasted from ˜290 Ma to ˜250 Ma. Although PPAIP rocks are petrologically and geochemically typical of rifts and have been suggested to be linked to rifting on the Pangea continental margin at the initiation of the Neotethys Ocean, there are no documented rift-related structures mapped in Permian rocks of the Peshawar Plain. We suggest that Permian rift-related structures have been dismembered and/or reactivated during shortening associated with India-Asia collision. Shortening in the area between the Main Mantle Thrust (MMT) and the Main Boundary Thrust (MBT) may be indicative of the subsurface northern extension of the Salt Range evaporites. Late Cenozoic sedimentary rocks of the Peshawar Plain deposited during and after Himalayan thrusting occupy a piggy-back basin on top of the thrust belt. Those sedimentary rocks have buried surviving evidence of Permian rift-related structures. Igneous rocks of the PPAIP have been both metamorphosed and deformed during the Himalayan collision and Cenozoic igneous activity, apart from the newly recognized Gohati volcanism, has involved only the intrusion of small cross-cutting granitic bodies concentrated in areas such as Malakand that are close to the MMT. Measurements on Chingalai Gneiss zircons have confirmed the occurrence of 816 ± 70 Ma aged rocks in the Precambrian basement of the Peshawar Plain that are comparable in age to rocks in the Malani igneous province of the Rajasthan platform ˜1000 km to the south.

  5. halogen Contents of igneous minerals as indicators of magmatic evolution of rocks associated with the Ray porphyry copper deposit, Arizona

    USGS Publications Warehouse

    Banks, Norman G.

    1976-01-01

    The contents of Cl, F, and H2O+ (calculated) in some hydrous igneous minerals in intrusive rocks of Laramide age (70-60 m.y.) near Ray, Ariz., appear to be related to the age and the chemistry of the whole-rock samples. Apatite and biotite in younger, more silicic rocks contain more F but less Cl and H2O+ than apatite and biotite in older, more mafic rock; the same relations hold for F and H2O+ in sphene. Correlations of the abundance of Cl, F, and H2O+ in hornblende with rock chemistry and age are not as strong as for apatite, biotite, and sphene; igneous (?) epidote does not contain Cl and F in amounts detectable by electron microprobe analysis. The contents of Cl, F, and H2O+ in whole-rock samples decrease with increasing differentiation index and decreasing age. Data for a single pluton of variable composition mirror the results for a suite of different plutons and dikes. The data are satisfactorily although not exclusively explained by postulating that the melts each contained progressively less Cl, F, and H2O and that the hydrons minerals consumed most of the Cl, F, and H2O in the magmas. The data may also be explained by postulating that (1) the stocks evolved Cl-bearing water during their ascent and crystallization, or that (2) Cl and H2O were concentrated during differentiation of the stocks but the minerals failed to record their buildup. Both alternative explanations find problems with and require special conditions to satisfy field, chemical, and experimental data. If many of the special conditions are not met, a nearby batholithic parent to the stocks is not a favorable source of the mineralized fluids at Ray. Propylitic alteration of biotite results in Cl-poor chlorites and may have provided some Cl to hydrothermal fluids; biotite may have also supplied some F to propylitizing fluids through alteration.

  6. The Kenna ureilite - An ultramafic rock with evidence for igneous, metamorphic, and shock origin

    NASA Technical Reports Server (NTRS)

    Berkley, J. L.; Brown, H. G.; Keil, K.; Carter, N. L.; Mercier, J.-C. C.; Huss, G.

    1976-01-01

    Ureilites are a rare group of achondrites. They are composed mainly of olivine and pigeonite in a matrix of carbonaceous material, including graphite, lonsdaleite, diamond, and metal. In most respects Kenna is a typical ureilite with the requisite mineralogical and chemical properties of the group. Differences of the Kenna ureilite from previously studied ureilites are related to a greater density, the occurrence of exceedingly minute quantities of feldspar, and a very strong elongation lineation of the silicate minerals. A description is presented of a study which indicates a complex history for Kenna, including igneous, mild metamorphic, and shock processes.

  7. Thermal neutron absorption cross sections for igneous rocks: Newberry Caldera, Oregon

    SciTech Connect

    Lysne, P.

    1990-01-01

    The thermal neutron absorption cross sections of geologic materials are of first-order importance to the interpretation of pulsed neutron porosity logs and of second-order importance to the interpretation of steady-state porosity logs using dual detectors. Even in the latter case, uncertainties in log response can be excessive whenever formations are encountered that possess absorption properties appreciably greater than the limestones used in most tool calibrations. These effects are of importance to logging operations directed at geothermal applications where formation vary from igneous to sedimentary and which may contain solution-deposited minerals with very large cross-section values. Most measurements of cross-section values for geologic materials have been made for hydrocarbon production applications. Hence, the specimen materials are sedimentary and clean in the sense that they are not altered by geothermal fluids. This investigation was undertaken to measure cross-section values from a sequence of igneous materials obtained from a single hole drilled in an active hydrothermal system. 3 refs., 1 fig.

  8. Crystal Size Distribution of Quartz Grains: A Means for Interpreting Igneous Textures in Dikes and Other Intrusive Rocks

    NASA Astrophysics Data System (ADS)

    Baker, L. J.; Candela, P. A.; Piccoli, P. M.

    2001-05-01

    Crystal size distribution analysis was applied to quartz crystals in intrusive igneous rocks in an attempt to describe quantitatively the degree to which the size distribution of the intrusive samples differs from that of extrusive rocks unaffected by near-solidus and sub-solidus recrystallization, grain boundary migration, and annealing. The samples include a seriate dike (width scale ~2 meters) found within the Courtright Shear Zone in the central Sierra Nevada (California), and three hypabyssal, Mesozoic-age plutons within the Great Basin (Nevada) including: the McCoy Pluton, granodiorite which exhibits a medium to coarse-grained hypidiomorphic texture; the Mill Canyon Stock, characterized by a hypidiomorphic-granular texture and which plots near the boundary between granite and granodiorite on a Streckeisen diagram; and the Trenton Canyon Pluton, which is a medium-grained hypidiomorphic-granular to slightly porphyritic granodiorite (Ratajeski, K., M.S. Thesis, Univ. MD, 1995). Crystal size distribution (CSD) analysis can be used to analyze quantitatively the texture of an igneous rock to derive information about the kinetics of crystallization. We used a batch crystallization formalism to model the crystallization kinetics of the intrusive rocks. In previous studies, CSD plots associated with extrusive samples have regularly exhibited a power-law crystal size distribution. In an attempt to determine the extent to which the CSD plots associated with intrusive samples approximate the CSD trends found for extrusive rocks, we measured the longest apparent diameters of quartz crystals in each sample for CSD analysis. Quartz was chosen for analysis because its aspect ratio approached unity. Therefore, the quartz grains can be approximated as a sphere in three dimensions, allowing for a simple area-to-volume conversion and minimizing stereological problems. Using the conductive heat transfer equation (dc = (κ t)1/2) applied to a dike with a cooling length of 1 meter

  9. Rates and processes of crystal growth in the system anorthite-albite. [magmatic liquids in igneous rock formation

    NASA Technical Reports Server (NTRS)

    Kirkpatrick, R. J.; Klein, L.; Uhlmann, D. R.; Hays, J. F.

    1979-01-01

    The growth rates and interface morphologies of crystals of synthetic compositions in the anorthite (CaAl2Si2O8)-albite (NaAlSi3O8) plagioclase feldspar system are measured in an investigation of the crystallization of igneous rocks. Mixed plagioclase glasses with compositions of 75% and 50% anorthite were observed using the microscope heating technique as they crystallized at temperatures near the liquidus, and 75%, 50% and 20% anorthite crystals were treated by resistance heating and observed at greater degrees of undercooling. Growth rates were found to be independent of time and to decrease with increasing albite content, ranging from 0.5 to 2 x 10 to the -5th cm/min. The crystal morphologies for all compositions are faceted near the liquidus and become progressively skeletal, dendritic and fibrillar with increasing undercooling.

  10. Field Observation of Joint Structures in Various Types of Igneous Rocks

    NASA Astrophysics Data System (ADS)

    Kano, Shingo; Tsuchiya, Noriyoshi

    2006-05-01

    In this study, field observations of natural fracture network systems in some intrusive and extrusive rocks were undertaken, to clarify the fracturing mechanism in the rocks. Shallow intrusives, whose depth of emplacement was less than several hundred metres, include the Momo-iwa Dacite dome on Rebun Island (Hokkaido), and Jodogahama Rhyolite in Iwate prefecture. Extrusive complexes studied include the Tojinbo Andesite and Ojima Rhyodacite in Fukui prefecture. Rocks of `granitic' composition were collected from the Takidani (Japan Alps) and Hijiori (Yamagata prefecture) plutons. The joint structure in Hijiori Granite was evaluated by analysis of core samples extracted from the HDR-3 geothermal production well. Based on detailed field observation, joint structures related to thermal contraction of a rock mass could be classified according to their inferred depth of formation. Joints from a near surface setting, such as shallow intrusive rocks and extrusives, tend to form pentagonal — hexagonal columnar structures (for a variety of rock types), whilst granitic rocks (from a deeper setting) typically exhibit a parallelepiped structure. The apparent differences in joint form are inferred to be dependent on the confining pressure, which acts on joint generation and propagation. In cases of non-confining pressure, such as the near-surface (shallow intrusive/extrusive) setting, joint networks typically form a columnar structure. On the contrary, confining pressure is considerably greater for deeper rock masses, and these form a parallelepiped joint structure.

  11. Determination of lead in igneous rocks by differential pulse anodic stripping voltammetry at an HMDE.

    PubMed

    Calderoni, G

    1981-01-01

    A versatile and sensitive voltammetric method has been used for the determination of lead in seven USGS standard rocks and in two CRPG (Centre des Recherches Pétrografiques et Géochimiques, Nancy) standard rocks. The results, showing satisfactory precision and accuracy, are discussed with respect to the sample treatment and the voltammetric method.

  12. Igneous phenocrystic origin of K-feldspar megacrysts in granitic rocks from the Sierra Nevada batholith

    USGS Publications Warehouse

    Moore, J.G.; Sisson, T.W.

    2008-01-01

    Study of four K-feldspar megacrystic granitic plutons and related dikes in the Sierra Nevada composite batholith indicates that the megacrysts are phenocrysts that grew in contact with granitic melt. Growth to megacrystic sizes was due to repeated replenishment of the magma bodies by fresh granitic melt that maintained temperatures above the solidus for extended time periods and that provided components necessary for K-feldspar growth. These intrusions cooled 89-83 Ma, are the youngest in the range, and represent the culminating magmatic phase of the Sierra Nevada batholith. They are the granodiorite of Topaz Lake, the Cathedral Peak Granodiorite, the Mono Creek Granite, the Whitney Granodiorite, the Johnson Granite Porphyry, and the Golden Bear Dike. Megacrysts in these igneous bodies attain 4-10 cm in length. All have sawtooth oscillatory zoning marked by varying concentration of BaO ranging generally from 3.5 to 0.5 wt%. Some of the more pronounced zones begin with resorption and channeling of the underlying zone. Layers of mineral inclusions, principally plagioclase, but also biotite, quartz, hornblende, titanite, and accessory minerals, are parallel to the BaO-delineated zones, are sorted by size along the boundaries, and have their long axes preferentially aligned parallel to the boundaries. These features indicate that the K-feldspar megacrysts grew while surrounded by melt, allowing the inclusion minerals to periodically attach themselves to the faces of the growing crystals. The temperature of growth of titanite included within the K-feldspar megacrysts is estimated by use of a Zr-in-titanite geothermometer. Megacryst-hosted titanite grains all yield temperatures typical of felsic magmas, mainly 735-760 ??C. Titanite grains in the granodiorite hosts marginal to the megacrysts range to lower growth temperatures, in some instances into the subsolidus. The limited range and igneous values of growth temperatures for megacryst-hosted titanite grains support the

  13. Distribution of chemical elements in calc-alkaline igneous rocks, soils, sediments and tailings deposits in northern central Chile

    NASA Astrophysics Data System (ADS)

    Oyarzún, Jorge; Oyarzun, Roberto; Lillo, Javier; Higueras, Pablo; Maturana, Hugo; Oyarzún, Ricardo

    2016-08-01

    This study follows the paths of 32 chemical elements in the arid to semi-arid realm of the western Andes, between 27° and 33° S, a region hosting important ore deposits and mining operations. The study encompasses igneous rocks, soils, river and stream sediments, and tailings deposits. The chemical elements have been grouped according to the Goldschmidt classification, and their concentrations in each compartment are confronted with their expected contents for different rock types based on geochemical affinities and the geologic and metallogenic setting. Also, the element behavior during rock weathering and fluvial transport is here interpreted in terms of the ionic potentials and solubility products. The results highlight the similarity between the chemical composition of the andesites and that of the average Continental Crust, except for the higher V and Mn contents of the former, and their depletion in Mg, Ni, and Cr. The geochemical behavior of the elements in the different compartments (rocks, soils, sediments and tailings) is highly consistent with the mobility expected from their ionic potentials, their sulfates and carbonates solubility products, and their affinities for Fe and Mn hydroxides. From an environmental perspective, the low solubility of Cu, Zn, and Pb due to climatic, chemical, and mineralogical factors reduces the pollution risks related to their high to extremely high contents in source materials (e.g., rocks, altered zones, tailings). Besides, the complex oxyanions of arsenic get bound by colloidal particles of Fe-hydroxides and oxyhydroxides (e.g., goethite), thus becoming incorporated to the fine sediment fraction in the stream sediments.

  14. Extensional tectonics during the igneous emplacement of the mafic-ultramafic rocks of the Barberton greenstone belt

    NASA Technical Reports Server (NTRS)

    Dewit, M. J.

    1986-01-01

    The simatic rocks (Onverwacht Group) of the Barberton greenstone belt are part of the Jamestown ophiolite complex. This ophiolite, together with its thick sedimentary cover occupies a complex thrust belt. Field studies have identified two types of early faults which are entirely confined to the simatic rocks and are deformed by the later thrusts and associated folds. The first type of fault (F1a) is regional and always occurs in the simatic rocks along and parallel to the lower contacts of the ophiolite-related cherts (Middle Marker and equivalent layers). These fault zones have previously been referred to both as flaser-banded gneisses and as weathering horizons. In general the zones range between 1-30m in thickness. Displacements along these zones are difficult to estimate, but may be in the order of 1-100 km. The structures indicate that the faults formed close to horizontal, during extensional shear and were therefore low angle normal faults. F1a zones overlap in age with the formation of the ophiolite complex. The second type of faults (F1b) are vertical brittle-ductile shear zones, which crosscut the complex at variable angles and cannot always be traced from plutonic to overlying extrusive (pillowed) simatic rocks. F1b zones are also apparently of penecontemporaneous origin with the intrusive-extrusive igneous processs. F1b zones may either represent transform fault-type activity or represent root zones (steepened extensions) of F1a zones. Both fault types indicate extensive deformation in the rocks of the greenstone belt prior to compressional overthrust tectonics.

  15. Extensional tectonics during the igneous emplacement of the mafic-ultramafic rocks of the Barberton greenstone belt

    NASA Astrophysics Data System (ADS)

    Dewit, M. J.

    The simatic rocks (Onverwacht Group) of the Barberton greenstone belt are part of the Jamestown ophiolite complex. This ophiolite, together with its thick sedimentary cover occupies a complex thrust belt. Field studies have identified two types of early faults which are entirely confined to the simatic rocks and are deformed by the later thrusts and associated folds. The first type of fault (F1a) is regional and always occurs in the simatic rocks along and parallel to the lower contacts of the ophiolite-related cherts (Middle Marker and equivalent layers). These fault zones have previously been referred to both as flaser-banded gneisses and as weathering horizons. In general the zones range between 1-30m in thickness. Displacements along these zones are difficult to estimate, but may be in the order of 1-100 km. The structures indicate that the faults formed close to horizontal, during extensional shear and were therefore low angle normal faults. F1a zones overlap in age with the formation of the ophiolite complex. The second type of faults (F1b) are vertical brittle-ductile shear zones, which crosscut the complex at variable angles and cannot always be traced from plutonic to overlying extrusive (pillowed) simatic rocks. F1b zones are also apparently of penecontemporaneous origin with the intrusive-extrusive igneous processs. F1b zones may either represent transform fault-type activity or represent root zones (steepened extensions) of F1a zones. Both fault types indicate extensive deformation in the rocks of the greenstone belt prior to compressional overthrust tectonics.

  16. A flow chart for the classification of igneous rocks in HTML — Is a web browser another way for teaching earth sciences?

    NASA Astrophysics Data System (ADS)

    Thum, Irmund

    1998-06-01

    The hypertext mark-up language (HTML) is a mark-up system used to create hypertext documents in use by the world-wide web (WWW). A flow chart for the classification of igneous rocks was written in HTML 3.2, a specification conforming to International Standard ISO 8879. HTML is ideal in teaching earth sciences on the Internet due to step by step nature of the classification of rocks because it is relatively straightforward to develop a series of graphically rich Web pages. The flow chart makes wide use of link techniques for references and terminology. As an essential result of the step by step technique, as proposed by the Recommendations of the International Union of Geological Sciences Subcommission on the Systematics of Igneous Rocks, the user should be able to classify any rock specimen with an appropriate nomenclature. Interested readers can download this software at the FTP-site from the server FTP.IAMG.ORG.

  17. Venus: chemical weathering of igneous rocks and buffering of atmospheric composition.

    PubMed

    Nozette, S; Lewis, J S

    1982-04-09

    Data from the Pioneer Venus radar mapper, combined with measurements of wind velocity and atmospheric composition, suggest that surface erosion on Venus varies with altitude. Calcium- and magnesium-rich weathering products are produced at high altitudes by gas-solid reactions with igneous minerals, then removed into the hotter lowlands by surface winds. These fine-grained weathering products may then rereact with the lower atmosphere and buffer the composition of the observed gases carbon dioxide, water vapor, sulfur dioxide, and hydrogen fluoride in some regions of the surface. This process is a plausible mechanism for the establishment in the lowlands of a calcium-rich mineral assemblage, which had previously been found necessary for the buffering of these species.

  18. Venus - Chemical weathering of igneous rocks and buffering of atmospheric composition

    NASA Technical Reports Server (NTRS)

    Nozette, S.; Lewis, J. S.

    1982-01-01

    Data from the Pioneer Venus radar mapper, combined with measurements of wind velocity and atmospheric composition, suggest that surface erosion on Venus varies with altitude. Calcium- and magnesium-rich weathering products are produced at high altitudes by gas-solid reactions with igneous minerals, then removed into the hotter lowlands by surface winds. These fine-grained weathering products may then rereact with the lower atmosphere and buffer the composition of the observed gases carbon dioxide, water vapor, sulfur dioxide, and hydrogen fluoride in some regions of the surface. This process is a plausible mechanism for the establishment in the lowlands of a calcium-rich mineral assemblage, which had previously been found necessary for the buffering of these species.

  19. Oxidative mobilization of cerium and uranium and enhanced release of "immobile" high field strength elements from igneous rocks in the presence of the biogenic siderophore desferrioxamine B

    NASA Astrophysics Data System (ADS)

    Kraemer, Dennis; Kopf, Sebastian; Bau, Michael

    2015-09-01

    Polyvalent trace elements such as the high field strength elements (HFSE) are commonly considered rather immobile during low-temperature water-rock interaction. Hence, they have become diagnostic tools that are widely applied in geochemical studies. We present results of batch leaching experiments focused on the mobilization of certain HFSE (Y, Zr, Hf, Th, U and rare earth elements) from mafic, intermediate and felsic igneous rocks in the presence and absence, respectively, of the siderophore desferrioxamine B (DFOB). Our data show that DFOB strongly enhances the mobility of these trace elements during low-temperature water-rock interaction. The presence of DFOB produces two distinct features in the Rare Earths and Yttrium (REY) patterns of leaching solutions, regardless of the mineralogical and chemical composition or the texture of the rock type studied. Bulk rock-normalized REY patterns of leaching solutions with DFOB show (i) a very distinct positive Ce anomaly and (ii) depletion of La and other light REY relative to the middle REY, with a concave downward pattern between La and Sm. These features are not observed in experiments with hydrochloric acid, acetic acid or deionized water. In DFOB-bearing leaching solutions Ce and U are decoupled from and selectively enriched relative to light REY and Th, respectively, due to oxidation to Ce(IV) and U(VI). Oxidation of Ce3+ and U4+ is promoted by the significantly higher stability of the Ce(IV) and U(VI) DFOB complexes as compared to the Ce(III) and U(IV) DFOB complexes. This is similar to the relationship between the Ce(IV)- and Ce(III)-pentacarbonate complexes that cause positive Ce anomalies in alkaline lakes. However, while formation of Ce(IV) carbonate complexes is confined to alkaline environments, Ce(IV) DFOB complexes may produce positive Ce anomalies even in mildly acidic and near-neutral natural waters. Siderophore-promoted dissolution processes also significantly enhance mobility of other 'immobile' HFSE

  20. Influence of temperature and water on subcritical crack growth parameters and long-term strength for igneous rocks

    NASA Astrophysics Data System (ADS)

    Nara, Yoshitaka; Yamanaka, Hiroshi; Oe, Yuma; Kaneko, Katsuhiko

    2013-04-01

    Understanding of time-dependent deformation and fracture propagation in rock is essential, since the knowledge of the long-term integrity of rock is required for many subsurface structures excavated in a rock mass. Time-dependent fracture propagation has been invoked as a potential key mechanism responsible for the increase in seismicity preceding earthquake ruptures and volcanic eruptions. In engineering projects, and in preventing natural hazards, the study of subcritical crack growth and the long-term strength of rock is necessary. Since the long-term strength is affected by the values of the subcritical crack growth parameters, it is important to know the influence of the surrounding environment on the subcritical crack growth parameters and long-term strength. The influence of the surrounding environment on the subcritical crack growth parameters, however, has not been completely clarified yet. In this study, the subcritical crack growth parameters were estimated under various environmental conditions on igneous rocks (andesite and granite) using the Double-Torsion method. Based on the results of subcritical crack growth parameters estimations, we calculated the long-term strength of rock. It was shown that the subcritical crack growth parameters were affected by the environmental conditions such as the temperature, humidity and existence of water. Especially, it was shown that the subcritical crack growth index in water was smaller than that in air. When the relative humidity of the air was higher, subcritical crack growth index tended to be smaller. The subcritical crack growth index at 90 per cent relative humidity was close to the value in water. By the calculation based on the results of our subcritical crack growth parameters estimation, it was shown that long-term strength decreased under the conditions of higher temperature, humidity in air and in water. It is concluded that the subcritical crack growth parameters and long-term strength are affected by

  1. Petrographic, mineralogic, and x-ray fluorescence analysis of lunar igneous-type rocks and spherules.

    PubMed

    Brown, G M; Emeleus, C H; Holland, J G; Phillips, R

    1970-01-30

    Three lunar rocks show almost identical mineralogy but grain sizes that vary from basaltic to gabbroic. Clinopyroxene is zoned from augite to subcalcic ferroaugite compositions and is accompanied by decrease in Cr, Al, and Ti. Plagioclase is zoned from 93 to 78 percent anorthite. Olivine (68 percent forsterite) is present in one rock and apatite is rare. Cristobalite, ilmenite with Ti-rich lamellae, ulvöspinel (often Cr-rich), troilite, and kamacite are low in trace elements. Glassy spherules are of basaltic or feldspathic (92 percent anorthite) composition but contain abundant iron spheres of taenite composition (13 percent Ni). Four rock analyses by x-ray fluorescence show affinity with terrestrial basalts but with anomalous amounts of Ti, Na, Cr, Zr, Y, Rb, Nb, Ni, Cu, and Zn.

  2. Alteration assemblages in the Miller Range and Elephant Moraine regions of Antarctica: Comparisons between terrestrial igneous rocks and Martian meteorites

    NASA Astrophysics Data System (ADS)

    Hallis, L. J.

    2013-02-01

    The weathering products present in igneous terrestrial Antarctic samples were analyzed, and compared with those found in the four Miller Range nakhlite Martian meteorites. The aim of these comparisons was to determine which of the alteration phases in the Miller Range nakhlites are produced by terrestrial weathering, and what effect rock composition has on these phases. Antarctic terrestrial samples MIL 05031 and EET 96400, along with the Miller Range nakhlites MIL 03346 and 090032, were found to contain secondary alteration assemblages at their externally exposed surfaces. Despite the difference in primary mineralogy, the assemblages of these rocks consist mostly of sulfates (jarosite in MIL 05031, jarosite and gypsum in EET 96400) and iddingsite-like Fe-clay. As neither of the terrestrial samples contains sulfur-bearing primary minerals, and these minerals are rare in the Miller Range nakhlites, it appears that SO42-, possibly along with some of the Na+, K+, and Ca+ in these phases, was sourced from wind-blown sea spray and biogenic emissions from the southern ocean. Cl enrichment in the terrestrially derived "iddingsite" of MIL 05031 and MIL 03346, and the presence of halite at the exterior edge of MIL 090032, can also be explained by this process. However, jarosite within and around the olivine-bound melt inclusions of MIL 090136 is present in the interior of the meteorite and, therefore, is probably the product of preterrestrial weathering on Mars.

  3. Evolving subduction zones in the Western United States, as interpreted from igneous rocks.

    PubMed

    Lipman, P W; Prostka, H J; Christiansen, R L

    1971-11-19

    Variations in the ratio of K(2)O to SiO(2) in andesitic rocks suggest early and middle Cenozoic subduction beneath the western United States along two subparallel imbricate zones dipping about 20 degrees eastward. The western zone emerged at the continental margin, but the eastern zone was entirely beneath the continental plate. Mesozoic subduction apparently occurred along a single steeper zone.

  4. Alkaline igneous rocks of Magnet Cove, Arkansas: Mineralogy and geochemistry of syenites

    USGS Publications Warehouse

    Flohr, M.J.K.; Ross, M.

    1990-01-01

    Syenites from the Magnet Cove alkaline igneous complex form a diverse mineralogical and geochemical suite. Compositional zoning in primary and late-stage minerals indicates complex, multi-stage crystallization and replacement histories. Residual magmatic fluids, rich in F, Cl, CO2 and H2O, reacted with primary minerals to form complex intergrowths of minerals such as rinkite, fluorite, V-bearing magnetite, F-bearing garnet and aegirine. Abundant sodalite and natrolite formed in pegmatitic segregations within nepheline syenite where Cl- and Na-rich fluids were trapped. During autometasomatism compatible elements such as Mn, Ti, V and Zr were redistributed on a local scale and concentrated in late-stage minerals. Early crystallization of apatite and perovskite controlled the compatible behavior of P and Ti, respectively. The formation of melanite garnet also affected the behaviour of Ti, as well as Zr, Hf and the heavy rare-earth elements. Pseudoleucite syenite and garnet-nepheline syenite differentiated along separate trends, but the two groups are related to the same parental magma by early fractionation of leucite, the presumed precursor of intergrowths of K-feldspar and nepheline. The Diamond Jo nepheline syenite group defines a different differentiation trend. Sphene-nepheline syenite, alkali syenite and several miscellaneous nepheline syenites do not consistently plot with the other syenite groups or each other on element and oxide variation diagrams, indicating that they were derived from still other parental syenite magmas. Mineral assemblages indicate that relatively high f{hook};O2, at or above the fayalite-magnetite-quartz buffer, prevailed throughout the crystallization history of the syenites. ?? 1990.

  5. Compositional variation in the chevkinite group: New data from igneous and metamorphic rocks

    USGS Publications Warehouse

    Macdonald, R.; Belkin, H.E.; Wall, F.; Baginski, B.

    2009-01-01

    Electron microprobe analyses are presented of chevkinite-group minerals from Canada, USA, Guatemala, Norway, Scotland, Italy and India. The host rocks are metacarbonates, alkaline and subalkaline granitoids, quartz-bearing pegmatites, carbonatite and an inferred K-rich tuff. The analyses extend slightly the range of compositions in the chevkinite group, e.g. the most MgO-rich phases yet recorded, and we report two further examples where La is the dominant cation in the A site. Patchilyzoned crystals from Virginia and Guatemala contain both perrierite and chevkinite compositions. The new and published analyses are used to review compositional variation in minerals of the perrierite subgroup, which can form in a wide range of host rock compositions and over a substantial pressure-temperature range. The dominant substitutions in the various cation sites and a generalized substitution scheme are described. ?? 2009 The Mineralogical Society.

  6. Thermal conductivity of lunar and terrestrial igneous rocks in their melting range.

    PubMed

    Murase, T; McBirney, A R

    1970-10-09

    The thermal conductivity of a synthetic lunar rock in its melting range is about half that of a terrestrial basalt. The low conductivity and increased efficiency of insulating crusts on lunar lavas will enable flows to cover great distances without being quenched by high radiant heat losses from the surface. For a given rate of heat production, the thermal gradient of the moon would be significantly steeper than that of the earth.

  7. Complex igneous processes and the formation of the primitive lunar crustal rocks

    NASA Technical Reports Server (NTRS)

    Longhi, J.; Boudreau, A. E.

    1979-01-01

    Crystallization of a magma ocean with initial chondritic Ca/Al and REE ratios such as proposed by Taylor and Bence (TB, 1975), is capable of producing the suite of primitive crustal rocks if the magma ocean underwent locally extensive assimilation and mixing in its upper layers as preliminary steps in formation of an anorthositic crust. Lunar anorthosites were the earliest permanent crustal rocks to form the result of multiple cycles of suspension and assimilation of plagioclase in liquids fractionating olivine and pyroxene. There may be two series of Mg-rich cumulate rocks: one which developed as a result of the equilibration of anorthositic crust with the magma ocean; the other which formed in the later stages of the magma ocean during an epoch of magma mixing and ilmenite crystallization. This second series may be related to KREEP genesis. It is noted that crystallization of the magma ocean had two components: a low pressure component which produced a highly fractionated and heterogeneous crust growing downward and a high pressure component which filled in the ocean from the bottom up, mostly with olivine and low-Ca pyroxene.

  8. Prolonged KREEP magmatism on the Moon indicated by the youngest dated lunar igneous rock.

    PubMed

    Borg, Lars E; Shearer, Charles K; Asmerom, Yemane; Papike, James J

    2004-11-11

    Primordial solidification of the Moon (or its uppermost layer) resulted in the formation of a variety of rock types that subsequently melted and mixed to produce the compositional diversity observed in the lunar sample suite. The initial rocks to crystallize from this Moon-wide molten layer (the magma ocean) contained olivine and pyroxene and were compositionally less evolved than the plagioclase-rich rocks that followed. The last stage of crystallization, representing the last few per cent of the magma ocean, produced materials that are strongly enriched in incompatible elements including potassium (K), the rare earth elements (REE) and phosphorus (P)--termed KREEP. The decay of radioactive elements in KREEP, such as uranium and thorium, is generally thought to provide the thermal energy necessary for more recent lunar magmatism. The ages of KREEP-rich samples are, however, confined to the earliest periods of lunar magmatism between 3.8 and 4.6 billion years (Gyr) ago, providing no physical evidence that KREEP is directly involved in more recent lunar magmatism. But here we present evidence that KREEP magmatism extended for an additional 1 Gyr, based on analyses of the youngest dated lunar sample.

  9. Primary colonization and breakdown of igneous rocks by endemic, succulent elephant trees (Pachycormus discolor) of the deserts in Baja California, Mexico.

    PubMed

    Bashan, Yoav; Vierheilig, Horst; Salazar, Bernardo G; de-Bashan, Luz E

    2006-07-01

    Trees growing in rocks without soil are uncommon. In two arid regions in Baja California, Mexico, field surveys found large numbers of rock-colonizing elephant trees (Pachycormus discolor (Benth.) Coville ex Standl. (Mexican name: copalquin) growing in igneous rocks (granite and basalt) as primary colonizers without the benefit of soil or with a very small amount of soil generated by their own growth. Many adult trees broke large granite boulders and were capable of wedging, growing in, and colonizing rocks and cliffs made of ancient lava flows. This is the first record of a tree species, apart from the previously recorded cacti, capable of primary colonization of rocks and rock rubble in hot deserts.

  10. Lead isotope compositions of Late Cretaceous and early Tertiary igneous rocks and sulfide minerals in Arizona: Implications for the sources of plutons and metals in porphyry copper deposits

    USGS Publications Warehouse

    Bouse, R.M.; Ruiz, J.; Titley, S.R.; Tosdal, R.M.; Wooden, J.L.

    1999-01-01

    Porphyry copper deposits in Arizona are genetically associated with Late Cretaceous and early Tertiary igneous complexes that consist of older intermediate volcanic rocks and younger intermediate to felsic intrusions. The igneous complexes and their associated porphyry copper deposits were emplaced into an Early Proterozoic basement characterized by different rocks, geologic histories, and isotopic compositions. Lead isotope compositions of the Proterozoic basement rocks define, from northwest to southeast, the Mojave, central Arizona, and southeastern Arizona provinces. Porphyry copper deposits are present in each Pb isotope province. Lead isotope compositions of Late Cretaceous and early Tertiary plutons, together with those of sulfide minerals in porphyry copper deposits and of Proterozoic country rocks, place important constraints on genesis of the magmatic suites and the porphyry copper deposits themselves. The range of age-corrected Pb isotope compositions of plutons in 12 Late Cretaceous and early Tertiary igneous complexes is 206Pb/204Pb = 17.34 to 22.66, 207Pb/204Pb = 15.43 to 15.96, and 208Pb/204Pb = 37.19 to 40.33. These Pb isotope compositions and calculated model Th/U are similar to those of the Proterozoic rocks in which the plutons were emplaced, thereby indicating that Pb in the younger rocks and ore deposits was inherited from the basement rocks and their sources. No Pb isotope differences distinguish Late Cretaceous and early Tertiary igneous complexes that contain large economic porphyry copper deposits from less rich or smaller deposits that have not been considered economic for mining. Lead isotope compositions of Late Cretaceous and early Tertiary plutons and sulfide minerals from 30 metallic mineral districts, furthermore, require that the southeastern Arizona Pb province be divided into two subprovinces. The northern subprovince has generally lower 206Pb/204Pb and higher model Th/U, and the southern subprovince has higher 206Pb/204Pb and

  11. A detailed paleomagnetic investigation of Cretaceous igneous rocks: New contributions from Colombia and Paraguay

    NASA Astrophysics Data System (ADS)

    Kapper, Lisa; Calvo-Rathert, Manuel; Cejudo Ruiz, Ruben; Sanchez Bettucci, Leda; Irurzun, Alicia; Carrancho, Ángel; Gogichaishvili, Avto; Morales, Juan; Sinito, Ana; Mejia, Victoria; Nivia Guevara, Alvaro

    2016-04-01

    We present rock magnetic results, paleodirections and -intensities from Cretaceous samples from two locations from South America. On the one hand we report paleomagnetic results from the Western Cordillera of Colombia from 15 sites north of Cali. These volcanic rock samples were related to age determinations from close localities of 92.5 ± 1.1 Ma on average, occuring during the Cretaceous Normal Superchron (CNS). On the other hand we show results from an alkaline dike swarm in the Asunción Rift, Eastern Paraguay. Previous investigations suggest that these dikes extruded in a rather short period of 126-127 Ma, during normal and reversed polarity field configuration, right before the onset of the CNS. Rock magnetic measurements of both sites show that the main magnetic component is a low-coercivity mineral, e.g., (titanium)magnetite, with a large range of grain sizes from multi- to single domain, or mixtures of several grain sizes in a sample. For the Colombian site we obtained an average Virtual Geomagnetic Pole (VGP), whose latitude compares well with those for South and North America of Besse and Courtillot (2002) with a similar age. For the determination of the Virtual Dipole Moments (VDMs) the Thellier-Coe method did not give successful results, probably due to minerals in the range of multidomain grain size. Therefore, we applied the multispecimen protocol on ten specimens. Six successful determinations produced an average VDM of 2.3 x 10-22 Am2. This value is rather low, but in good agreement with other data from the same time period. Directional investigation of the Eastern Paraguayan dike swarm show highly clustered promising results with six out of 22 sites having an α95 ≤ 10.0° . Most of these sites show a reversed polarity; however, one intermediate polarity site has a very reliable direction as well. This and the occurrence of normal polarity sites suggest that the dikes may have not appeared at the same time but rather during the transition from

  12. Geochemistry of oceanic igneous rocks - Ridges, islands, and arcs - With emphasis on manganese, scandium, and vanadium

    USGS Publications Warehouse

    Doe, B.R.

    1997-01-01

    A database on a number of elements in oceanic volcanic rocks is presented, including the principal major-element oxides - SiO2, TiO2, Al2O3, Fe2O3(T), MnO, MgO, CaO, Na2O, K2O, and P2O5 (where T refers to total iron) - and the trace elements - Ba, Ce, Cr, Cu, Ni, Sc, Sr, V, Pb (mainly by isotope dilution), Yb, Zn, and Zr. Interpretations are given for transition metals, with emphasis on Mn, Sc, and V, in order to determine the concentration of the elements in primitive melts and assess their trends in magmatic differentiation. Transition metals are not enriched in plagioclase, so all are incompatible with pure plagioclase removal - that is, they become enriched in the melt. Both Cr and Ni are known to be highly compatible with olivine separation - i.e., they are depleted in the melt early in differentiation. Also, Sc is compatible with clinopyroxene (Cpx) removal from the melt and is depleted by separation of Cpx. Copper does not fit well in any of the principal silicates, but Cu, like Ni, is greatly enriched in sulfides that may remain in the source or separate from the magma. Decreasing Ni abundances and increasing Cu contents during differentiation are a sign of olivine separation. In the analysis presented herein, V - in the absence of Cpx separation - is found to behave remarkably like the moderately incompatible element Zn, and these two elements add to the list of element pairs of similar incompatibility whose ratios are insensitive to differentiation and to submarine weathering as well. Both are enhanced in titanomagnetite, so both would he compatible during titanomagnetite separation. When Cpx separates, however, V becomes compatible like Sc, but Zn remains incompatible. Thus, decreasing V (and Sc) contents and increasing Zn contents during differentiation are a sign of Cpx separation. Manganese often behaves much like Zn and therefore is moderately incompatible, but Mn is less compatible than Zn and V in titanomagnetite. Thus, decreasing Zn and V with

  13. 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

  14. Zinc, copper, and lead geochemistry of oceanic igneous rocks - ridges, islands, and arcs

    USGS Publications Warehouse

    Doe, B.R.

    1995-01-01

    Variations in the abundances of Zn, Cu, and Pb are found to be useful in identifying tectonic regimes and separating ocean-island basalts into enriched- and depleted-source categories. The average Zn, Cu, and Pb contents of normal mid-ocean ridge basalts (N-MORB) are 84, 70, and 0.35 ppm, respectively. Differences in average Zn contents for various ridges reflect more the varying degrees of differentiation than variations of Zn content in the source rocks. At a Mg# of 70, or Mg#70, which is taken to represent primitive MORB, many MORB sequences converge at a Zn content of 58??6 ppm, which is close to the value for primitive mantle (50 ppm) and ordinary chondrites (~55 ppm). -from Author

  15. Crystallization studies of lunar igneous rocks: crystal structure of synthetic armalcolite.

    PubMed

    Lind, M D; Housley, R M

    1972-02-04

    Crystals of armalcolite, Mg(0.5)Fe(0.5)Ti(2)O(5), up to several millimeters in length have been grown from a glass initially having the composition of lunar rock 10017. A single-crystal x-ray study has confirmed that the crystals are isomorphous with pseudobrookite and has shown that the cations are strongly ordered, with the Ti(4+) ions occupying the 8f sites and the Fe(2+) and Mg(2+) ions randomly distributed over the 4c sites. An examination of karrooite, MgTi(2)O(5), has revealed a similar distribution of Mg(2+) and Ti(4+) ions. A reexamination of earlier x-ray and Mössbauer data for pseudobrookite, Fe(2)TiO(5), has shown that it is more consistent with this type of ordering than with the inverse structure that has been generally assumed.

  16. Epithermal neutron activation, radiometric, correlation and principal component analysis applied to the distribution of major and trace elements in some igneous and metamorphic rocks from Romania.

    PubMed

    Cristache, C I; Duliu, O G; Culicov, O A; Frontasyeva, M V; Ricman, C; Toma, M

    2009-05-01

    Six major (Na, Al, K, Ca, Ti, Fe) and 28 trace (Sc, Cr, V, Mn, Co, Zn, Cu, As, Br, Sr, Rb, Zr, Mo, Sn, Sb, Ba, Cs, La, Ce, Nd, Eu, Sm, Tb, Hf, Ta, W, Th and U) elements were determined by epithermal neutron activation analysis (ENAA) in nine Meridional Carpathian and Macin Mountains samples of igneous and metamorphic rocks. Correlation and principal factor analysis were used to interpret data while natural radionuclides radiometry shows a good correlation with ENAA results.

  17. Anomalous radionuclide content of three altered igneous dikes at Little Rock, Arkansas

    SciTech Connect

    Bonner, J.B. ); Martin, R.C.; Ledger, E.B. )

    1993-02-01

    Gamma-ray spectroscopy shows anomalous radionuclide contents for two altered alkalic dikes in Little Rock, Arkansas, while a third dike shows normal values. These Cretaceous dikes, locally termed phonolites, are pervasively altered to kaolinite. Samples from the contacts of the two anomalous dikes with the Big Fork Chert show average uranium values of 40 ppm and average thorium values of 22.7 ppm. Samples from the center of the dikes have average values of 30.3 ppm U and 23.1 ppm Th. A third altered dike has average radionuclide values of 11.6 ppm U and 12.8 ppm Th. Leaching experiments with 1N H[sub 2]SO[sub 4] removed only 40% of the uranium while H[sub 2]O removed 12%. The anomalous radionuclide values are due to phases high in uranium located in the volcanic glasses and possible rare earth minerals of the original phonolite. Alteration of the dikes occurred during the Tertiary as warm, tropical groundwaters decomposed the feldspars, feldspathoids, micas, and volcanic glass.

  18. Crystallization from a vapor phase in igneous rocks -- A conceptual model

    SciTech Connect

    Kleck, W.D. )

    1993-04-01

    Euhedral, late-stage crystals in pocket pegmatite and in vesicles of volcanic rocks are commonly cited as examples of crystallization from a vapor phase. If, however, crystallization takes place only from the cavity forming vapor, that vapor cannot contain sufficient material for the formation of the observed crystals. The approximate amount of H[sub 2]O vapor and percentage of dissolved silicate matter (1) for shallow pocket pegmatite is 0.5 g/cm[sup 3] and 0.3 percent; (2) for vesicles is 0.002 g/cm[sup 3] and [much lt]1 percent. These values show that the silicate matter dissolved in the vapor is insufficient for the formation of the observed crystals. No (or little) recharge of the vapor is an unstated assumption in most discussions of enclosed cavities. This, however, is not quite correct. For a simplified system, four phases will exist in equilibrium: (1) mineral grains growing from liquid, (2) late-stage, H[sub 2]O-enriched, silicate liquid, (3) vapor, (4) crystals growing from vapor. The total system (for transferal of silicate matter) is given. Little silicate matter is dissolved in the vapor at any one time, but it is replenished as the crystals grow. The vapor becomes a continuously resupplied reservoir of dissolved silicate matter; crystallization from the vapor continues until the silicate liquid is depleted.

  19. Characterisation of yeasts isolated from deep igneous rock aquifers of the Fennoscandian Shield.

    PubMed

    Ekendahl, S; O'Neill, A H; Thomsson, E; Pedersen, K

    2003-11-01

    The diversity of prokaryotes in the groundwater deep below the surface of the Baltic Sea at the Aspö Hard Rock Laboratory (HRL) in southeast Sweden is well documented. In addition, there is some evidence that eukaryotes, too, are present in the deep groundwater at this site, although their origins are uncertain. To extend the knowledge of eukaryotic life in this environment, five yeast, three yeastlike, and 17 mold strains were isolated from Aspö HRL groundwater between 201 and 444 m below sea level. Phenotypic testing and phylogenetic analysis of 18S rDNA sequences of the five yeast isolates revealed their relationships to Rhodotorula minuta and Cryptococcus spp. Scanning and transmission electron microscopy demonstrated that the strains possessed morphological characteristics typical for yeast, although they were relatively small, with an average length of 3 micro m. Enumeration through direct counting and most probable number methods showed low numbers of fungi, between 0.01 and 1 cells mL(-1), at some sites. Five of the strains were characterized physiologically to determine whether they were adapted to life in the deep biosphere. These studies revealed that the strains grew within a pH range of 4-10, between temperatures of 4 degrees C and 25-30 degrees C, and in NaCl concentrations from 0 to 70 g L(-1). These growth parameters suggest a degree of adaptation to the groundwater at Aspö HRL. Despite the fact that these eukaryotic microorganisms may be transient members of the deep biosphere microbial community, many of the observations of this study suggest that they are capable of growing in this extreme environment.

  20. Paleozoic to Triassic ocean opening and closure preserved in Central Iran: Constraints from the geochemistry of meta-igneous rocks of the Anarak area

    NASA Astrophysics Data System (ADS)

    Buchs, David M.; Bagheri, Sasan; Martin, Laure; Hermann, Joerg; Arculus, Richard

    2013-07-01

    The Anarak area belongs to an ophiolitic belt along the northern border of the Central-East Iranian Microcontinent, and is thought to contain fragments of the former Paleotethys and Neotethys oceans. A wide range of meta-igneous rocks from the Late Paleozoic to Triassic Anarak Metamorphic Complex (AMC) and nearby Meraji area have been studied to constrain the origins and modes of emplacement of oceanic remnants in Central Iran. Our samples occur as layers and lenses embedded in extensive sequences of deformed meta-sediments and smaller bodies of serpentinized ultramafic rocks. Petrographical and geochemical data combined with field and satellite observations allow recognition of seven types of meta-igneous rocks preserved from low grade to blueschist facies conditions. Their origins based on relative abundances of immobile trace elements include subduction zone, mid-ocean ridge, ocean intraplate, and continental rift settings. These data and existing geochronological constraints show the AMC formed an accretionary complex formed/exhumed incrementally during the Carboniferous, Permo-triassic and Triassic. Igneous rocks from Meraji formed in the Early Devonian due to opening of the Paleotethys, and belong to a rift sequence extending over 300 km along the edge of the Central-East Iranian Microcontinent. The AMC and nearby rock associations record the evolution of the Paleotethys during a complete Wilson Cycle between ca. 450 and 225 Ma, with implications for: (1) continental rifting; (2) ocean opening; (3) subduction initiation; (4) ocean intraplate and continued mid-ocean volcanism; (5) ridge subduction; and (6) final closure of the ocean during continent-continent collision. Alternate interpretations of the Anarak metabasites are possible, but require radical departures from the widely accepted model for tectonic evolution of the Paleotethys, with the existence of Paleotethyan backarc basin(s) and Permian or earlier collision of continental blocks in Central Iran

  1. Alteration processes in igneous rocks of the michilla mining area, coastal range, northern chile, and their relation with copper mineralisation

    NASA Astrophysics Data System (ADS)

    Oliveros, V.; Aguirre, L.; Townley, B.

    2003-04-01

    A 10 km thick homoclinal sequence of intermediate volcanic and sedimentary Jurassic rocks crops out in the Michilla mining area, Coastal Range, northern Chile (22-22°45S, 70-70°15W). Cretaceous plutons, intermediate to acid in composition, intrude this sequence together with numerous small basic to acid dykes and stocks. Main deposits are stratabound Cu-(Ag) with the ore minerals emplaced at the porous tops of the volcanic flows. However, some discordant orebodies, e.g. hydrothermal breccias, exist within the manto-type deposits. The volcanic sequence, and a minor part of the plutonic rocks, have been affected by three different alteration processes, each of them with their distinct mineral assemblages reflecting that every process was developed under different physicochemical conditions. The volcanic rocks far from the mining area are affected by a regional scale alteration process, basically isochemical. Its products are typical of a low-grade event: chl + ep +qtz + ttn (+- ab +- cal) with no ore minerals associated. The temperature interval, estimated by the chlorite geothermometer, ranges between 250 and 350°C. This alteration is either due to very low grade burial metamorphism or to hydrothermalism related to the Late Jurassic - Cretaceous plutonism. Inside the mining district the volcanic rocks are affected by a local scale alteration process originated by the intrusion of small stocks and dykes. This event is characterized by strong sodic metasomatism and minor Mg mobility. Two stages probably occurred as suggested by the two main mineral assemblages present, a propylitic (ab + ep + chl + act + ttn + qtz) and a quartz-sericitic one (ab + ser + qtz + tnn). They would reflect the changes in temperature, water/rock ratio and pH conditions during the whole process. Ore minerals related to this alteration are chalcopyrite, chalcocite and minor bornite and native silver. A temperature interval of 200-300°C is indicated by the chlorite geothermometer for the

  2. The isotopic composition of lead in potassium feldspars from some 1.0-b.y. old North American igneous rocks

    USGS Publications Warehouse

    Zartman, R.E.; Wasserburg, G.J.

    1969-01-01

    The isotopic composition of lead and the uranium, thorium and lead concentrations in potassium feldspars are determined for more than 30 1.0-b.y. old North American igneous rocks. Samples representing a broad spectrum in petrographic type and mode of occurrence were chosen; an effort was made to include only rocks having well-documented ages from 950 to 1140 m.y. and showing minimal evidence of subsequent metamorphism. Most samples, including those from extensive terranes of contemporaneous age, have limited lead isotope variations ( Pb206 Pb204 = 16.74-17.38; Pb207 Pb204 = 15.39-15.59; Pb208 Pb204 = 36.38-37.10), which yield model ages close to the radiometric ages. Granite, pegmatite, and rhyolite from within the Grenville province of Canada and age-equivalent rocks of New York, Virginia, Texas, and Colorado and granophyric units associated with the Duluth Gabbro Complex of Minnesota are among the materials yielding this main isotopic spectrum. Several samples were encountered which had isotopic compositions very different from the above group. Lead showing a marked deficiency in radiogenic isotopes was found in two granitic bodies associated with older Labrador Trough rocks from Quebec, in a rapakivi granite from southern Nevada, and in a small granite stock from Mellen, Wisconsin. These occurrences all involve small intrusions of granite which lie near considerably older areas of basement rock. Model ages calculated from the Pb206 Pb204 ratio are older than the age of the intrusions and approach the age of the host basement rock. Several possible interpretations are offered to explain the isotopic behavior encountered in this study. In particular, a "vertically differentiated crust" model is proposed which will account for both the main spectrum and the anomalous lead. The significance of lead isotopic studies in understanding crustal structure in continental regions is discussed. ?? 1969.

  3. Primary uranium sources for sedimentary-hosted uranium deposits in NE China: insight from basement igneous rocks of the Erlian Basin

    NASA Astrophysics Data System (ADS)

    Bonnetti, Christophe; Cuney, Michel; Bourlange, Sylvain; Deloule, Etienne; Poujol, Marc; Liu, Xiaodong; Peng, Yunbiao; Yang, Jianxing

    2017-03-01

    Carboniferous-Permian, Triassic and Jurassic igneous basement rocks around the Erlian Basin in northeast China have been investigated through detailed mineralogical, whole-rock geochemistry, geochronological data and Sm-Nd isotope studies. Carboniferous-Permian biotite granites and volcanic rocks belong to a calc-alkaline association and were emplaced during the Late Carboniferous-Early Permian (313 ± 1-286 ± 2 Ma). These rocks are characterised by positive ɛNd( t) (3.3-5.3) and fairly young T DM model ages (485-726 Ma), suggesting a dominant derivation from partial melting of earlier emplaced juvenile source rocks. Triassic biotite granites belong to a high-K calc-alkaline association and were emplaced during the Middle Triassic (243 ± 3-233 ± 2 Ma). Their negative ɛNd( t) (-2 to -0.1) and higher T DM model ages (703-893 Ma) suggest a contribution from Precambrian crust during the magma generation processes, leading to a strong enrichment in K and incompatible elements such as Th and U. Highly fractionated magmas crystallised in U-rich biotite (up to 21 ppm U) and two-mica granites. In biotite granite, the major U-bearing minerals are uranothorite and allanite. They are strongly metamict and the major part of their uranium (90 %) has been released from the mineral structure and was available for leaching. Mass balance calculations show that the Triassic biotite granites may have, at least, liberated ˜14,000 t U/km3 and thus correspond to a major primary uranium source for the U deposits hosted in the Erlian Basin.

  4. Middle Miocene nepheline-bearing mafic and evolved alkaline igneous rocks at House Mountain, Arizona Transition Zone, north-central Arizona

    SciTech Connect

    Wittke, J.; Holm, R.F.; Ranney, W.D.R. . Dept. of Geology)

    1993-04-01

    The Middle Miocene House Mountain shield volcano is located on the northern margin of the Arizona Transition Zone, about 7 km SW of Sedona, AZ. Deep erosion has exposed internal structural and stratigraphic relationships of the volcano. Mapping documents two igneous suites: (1) alkali basalt to trachyte and alkali-feldspar syenite, and (2) olivine melanephelinite, nepheline monzodiorite, nepheline monzosyenite and nepheline syenite. The rocks of the first suite occur as dikes and flows, which, with a thick pyroclastic section, are the principal units of the volcano. The melanephelinite is nonvesicular and intruded as a large irregular dike and several smaller dikes. The nepheline-bearing syenitic rocks, which are phaneritic with nepheline and clinopyroxene crystals up to 1 cm in diameter, occur as pods and sheets within the melanephelinite. Also within the melanephelinite are wispy leucocratic segregations, syenitic fracture-fillings, and ocelli. The largest phaneritic sheet is [approx]18 m thick; it displays crude subhorizontal compositional banding and vuggy surfaces. The latter indicate that the magmas were fluid-rich. Compositions intermediate between the melanephelinite and syenitic rocks have not been found. Although the syenitic rocks are coarse-grained, mapping indicates the they are near the summit of the volcano and were probably emplaced at a depth of less than 1 km, possibly of only a few hundred meters. The field relationships of the phaneritic rocks can be explained by ascent and coalescence of immiscible syenitic liquids within the melanephelinite dike. Calculated density contrasts between melanephelinite and syenitic liquids exceed 0.2 g/cm[sup 3].

  5. Multifractal magnetic susceptibility distribution models of hydrothermally altered rocks in the Needle Creek Igneous Center of the Absaroka Mountains, Wyoming

    USGS Publications Warehouse

    Gettings, M.E.

    2005-01-01

    Magnetic susceptibility was measured for 700 samples of drill core from thirteen drill holes in the porphyry copper-molybdenum deposit of the Stinkingwater mining district in the Absaroka Mountains, Wyoming. The magnetic susceptibility measurements, chemical analyses, and alteration class provided a database for study of magnetic susceptibility in these altered rocks. The distribution of the magnetic susceptibilities for all samples is multi-modal, with overlapping peaked distributions for samples in the propylitic and phyllic alteration class, a tail of higher susceptibilities for potassic alteration, and an approximately uniform distribution over a narrow range at the highest susceptibilities for unaltered rocks. Samples from all alteration and mineralization classes show susceptibilities across a wide range of values. Samples with secondary (supergene) alteration due to oxidation or enrichment show lower susceptibilities than primary (hypogene) alteration rock. Observed magnetic susceptibility variations and the monolithological character of the host rock suggest that the variations are due to varying degrees of alteration of blocks of rock between fractures that conducted hydrothermal fluids. Alteration of rock from the fractures inward progressively reduces the bulk magnetic susceptibility of the rock. The model introduced in this paper consists of a simulation of the fracture pattern and a simulation of the alteration of the rock between fractures. A multifractal model generated from multiplicative cascades with unequal ratios produces distributions statistically similar to the observed distributions. The reduction in susceptibility in the altered rocks was modelled as a diffusion process operating on the fracture distribution support. The average magnetic susceptibility was then computed for each block. For the purpose of comparing the model results with observation, the simulated magnetic susceptibilities were then averaged over the same interval as the

  6. On the age of the Onverwacht Group, Swaziland sequence, South Africa. [radioactive dating of stratified igneous rocks

    NASA Technical Reports Server (NTRS)

    Jahn, B.-M.; Shih, C.-Y.

    1974-01-01

    Some rocks of the Onverwacht Group, South Africa, have been analyzed for Rb and Sr concentrations and Sr isotopic composition. These rocks include volcanic rocks, layered ultramafic differentiates and cherty sediments. Whole rock data indicate that the Rb-Sr isotopic systems in many samples were open and yield no reasonable isochron relationships. However, the data of mineral separates from a basaltic komatiite define a good isochron of 3.50 (plus or minus .2) b.y. with an initial Sr-87/Sr-86 ratio of 0.70048 plus or minus 5. The orthodox interpretation of this age is the time of the low grade metamorphism. It is reasonable to assume that the age of 3.50 b.y. might also represent the time of initial Onverwacht volcanism and deposition. The initial Sr-87/Sr-86 ratio obtained above is important to an understanding of the Sr isotopic composition of the Archean upper mantle.

  7. Models of single-stage concomitant potassium-argon exchange: an interpretation of discordant whole rock K-Ar data from hydrothermally altered igneous rocks of the South Pennine Orefield, U.K.

    NASA Astrophysics Data System (ADS)

    Mitchell, J. G.; Ineson, P. R.

    1988-04-01

    A model of single-stage concomitant potassium and argon exchange is advanced to explain the existence of rectilinear "isochrons" in potassium-argon correlation diagrams produced from suites of altered rocks. Negative isochron intercepts are shown to be a consequence of fractional argon loss which exceeds potassium loss, and it is demonstrated that no information of immediate geological significance can be obtained from the gradient of such an isochron. Bounds to the "primary formation age" and "age of exchange event" may be established using extreme values of the observed potassium content and from estimates based on the inferred petrology and chemistry of the unaltered rock and/or its alteration products. Ten Carboniferous igneous units from the South Pennine Orefield (involving-thirty-eight independent samples) are investigated by means of the model and eight of the units are consistent with a model of potassium and argon exchange occurring in earliest Mesozoic times (ca. 200 Ma). It is argued that this conclusion augments the already substantial body of evidence for an identifiable widespread igneous and hydrothermal province associated with early rifting processes in the North Atlantic.

  8. Geochemical diversity in first rocks examined by the Curiosity Rover in Gale Crater: Evidence for and significance of an alkali and volatile-rich igneous source

    NASA Astrophysics Data System (ADS)

    Schmidt, M. E.; Campbell, J. L.; Gellert, R.; Perrett, G. M.; Treiman, A. H.; Blaney, D. L.; Olilla, A.; Calef, F. J.; Edgar, L.; Elliott, B. E.; Grotzinger, J.; Hurowitz, J.; King, P. L.; Minitti, M. E.; Sautter, V.; Stack, K.; Berger, J. A.; Bridges, J. C.; Ehlmann, B. L.; Forni, O.; Leshin, L. A.; Lewis, K. W.; McLennan, S. M.; Ming, D. W.; Newsom, H.; Pradler, I.; Squyres, S. W.; Stolper, E. M.; Thompson, L.; VanBommel, S.; Wiens, R. C.

    2014-01-01

    first four rocks examined by the Mars Science Laboratory Alpha Particle X-ray Spectrometer indicate that Curiosity landed in a lithologically diverse region of Mars. These rocks, collectively dubbed the Bradbury assemblage, were studied along an eastward traverse (sols 46-102). Compositions range from Na- and Al-rich mugearite Jake_Matijevic to Fe-, Mg-, and Zn-rich alkali-rich basalt/hawaiite Bathurst_Inlet and span nearly the entire range in FeO* and MnO of the data sets from previous Martian missions and Martian meteorites. The Bradbury assemblage is also enriched in K and moderately volatile metals (Zn and Ge). These elements do not correlate with Cl or S, suggesting that they are associated with the rocks themselves and not with salt-rich coatings. Three out of the four Bradbury rocks plot along a line in elemental variation diagrams, suggesting mixing between Al-rich and Fe-rich components. ChemCam analyses give insight to their degree of chemical heterogeneity and grain size. Variations in trace elements detected by ChemCam suggest chemical weathering (Li) and concentration in mineral phases (e.g., Rb and Sr in feldspars). We interpret the Bradbury assemblage to be broadly volcanic and/or volcaniclastic, derived either from near the Gale crater rim and transported by the Peace Vallis fan network, or from a local volcanic source within Gale Crater. High Fe and Fe/Mn in Et_Then likely reflect secondary precipitation of Fe3+ oxides as a cement or rind. The K-rich signature of the Bradbury assemblage, if igneous in origin, may have formed by small degrees of partial melting of metasomatized mantle.

  9. Geology and genesis of the Toongi rare metal (Zr, Hf, Nb, Ta, Y and REE) deposit, NSW, Australia, and implications for rare metal mineralization in peralkaline igneous rocks

    NASA Astrophysics Data System (ADS)

    Spandler, Carl; Morris, Caitlin

    2016-12-01

    The Toongi Deposit, located in central NSW, Australia, hosts significant resources of Zr, Hf, Nb, Ta, Y and REE within a small (ca. 0.3 km2), rapidly cooled trachyte laccolith. Toongi is part of regional Late Triassic to Jurassic alkaline magmatic field, but is distinguished from the other igneous bodies by its peralkaline composition and economically significant rare metal content that is homogenously distributed throughout the trachyte body. The primary ore minerals are evenly dispersed throughout the rock and include lueshite/natroniobite and complex Na-Fe-Zr-Nb-Y-REE silicate minerals dominated by a eudialyte group mineral (EGM). The EGM occurs in a unique textural setting in the rock, commonly forming spheroidal or irregular-shaped globules, herein called "snowballs", within the rock matrix. The snowballs are often protruded by aegirine and feldspar phenocrysts and contain swarms of fine aegirine and feldspar grains that often form spiral or swirling patterns within the snowball. Secondary ore minerals include REE carbonates, Y milarite, catapleiite and gaidonnayite that fill fractures and vesicles in the rock. Based on bulk-rock geochemical and Nd isotope data, and thermodynamic modelling of magma fractionation, the alkaline rocks of the region are interpreted to represent extrusive to hyperbyssal products of mantle-derived magma that ponded at mid-crustal levels (ca. 0.3 GPa) and underwent extensive fractionation under low-oxygen fugacity conditions. The high Na2O, peralkaline nature of the Toongi Deposit trachyte developed via extensive fractionation of an alkali olivine basalt parental magma initially in the mid-crust and subsequently at shallow levels (ca. 0.1 GPa). This extended fractionation under low fO2 and relatively low H2O-activity conditions limited volatile release and allowed build-up of rare metal contents to ore grades. We speculate that the ore minerals may have originally formed from rare metal-rich sodic-silicate melt that formed immiscible

  10. Genesis of Syntectonic Hydrothermal Veins in the Igneous Rock of Teschenite Association (Outer Western Carpathians, Czech Republic): Growth Mechanism and Origin of Fluids

    NASA Astrophysics Data System (ADS)

    Urubek, Tomáš; Dolníček, Zdeněk; Kropáč, Kamil

    2015-01-01

    Hydrothermal mineralization hosted by the Lower Cretaceous igneous rock of the teschenite association at Jasenice (Silesian Unit, Flysch Belt, Outer Western Carpathians) occurs in two morphological types - irregular vein filled by granular calcite and regular composite vein formed by both fibrous and granular calcite and minor chlorite, quartz, and pyrite. Crosscutting evidence indicates that the granular veins are younger than the composite vein. The composite vein was formed by two mechanisms at different times. The arrangement of solid inclusions in the marginal fibrous zone suggests an episodic growth by the crack-seal mechanism during syntectonic deformation which was at least partially driven by tectonic suction pump during some stages of the Alpine Orogeny. Both the central part of the composite vein and monomineral veins developed in a brittle regime. In these cases, the textures of vein suggest the flow of fluids along an open fracture. The parent fluids of both types of vein are characterized by low temperatures (Th=66-163 °C), low salinities (0.4 to 3.4 wt. % NaCl eq.), low content of strong REE-complexing ligands, and δ18O and δ13C ranges of + 0.2/+12.5 %. SMOW and -11.8/-14.1 %. PDB, respectively. The parent fluids are interpreted as the results of mixing of residual seawater and diagenetic waters produced by dewatering of clay minerals in the associ-ated flysch sediments. The flow of fluids was controlled by tectonic deformation of the host rock.

  11. Ultramafic and mafic rocks from the Garret Transform Fault near 13°30'S on the East Pacific Rise: Igneous petrology

    NASA Astrophysics Data System (ADS)

    Hébert, Réjean; Bideau, Daniel; Hekinian, Roger

    1983-10-01

    Serpentinized peridotites, metagabbros and fresh basaltic rocks were dredged from the Garret Transform Fault near 13°S on the East Pacific Rise. Two dredge hauls taken on the northern wall (from about 3100-3600 m) consisted of aphyric and picritic basalts; while peridotites, gabbros and moderately phyric basalts were recovered in a single dredge located near the deepest part (4616-4820 m) of the transform valley. Well preserved igneous textures and mineralogical assemblages enable us to differentiate between tectonites (including harzburgites and clinopyroxene-bearing harzburgites) and cumulates (consisting of plagioclase-dunite, troctolites, olivine-gabbros and ilmenite-gabbros). The harzburgites are likely to represent deep-seated peridotites left after extraction of basaltic melt during upper mantle partial melting of a lherzolite. The ultramafic cumulates underwent some deformation and show textural and mineralogical evidences which suggest formation at a minimum depth corresponding to the very lower crust. It is also inferred that the composition of the coexisting liquid along with early cumulus crystals has a ratio Mg/(Mg + Fe 2+) of 0.7, high CaO/Na 2O ratios and a low Ni content (about 150 ppm) when compared to similar rock types from Atlantic fracture zones. Subsequent uplift during rifting of the oceanic lithosphere enhanced plastic deformation, subsolidus recrystallization and retrogressive metamorphism of the gabbros and the ultramafics.

  12. Development of a fully automated open-column chemical-separation system—COLUMNSPIDER—and its application to Sr-Nd-Pb isotope analyses of igneous rock samples

    NASA Astrophysics Data System (ADS)

    Miyazaki, Takashi; Vaglarov, Bogdan Stefanov; Takei, Masakazu; Suzuki, Masahiro; Suzuki, Hiroaki; Ohsawa, Kouzou; Chang, Qing; Takahashi, Toshiro; Hirahara, Yuka; Hanyu, Takeshi; Kimura, Jun-Ichi; Tatsumi, Yoshiyuki

    A fully automated open-column resin-bed chemical-separation system, named COLUMNSPIDER, has been developed. The system consists of a programmable micropipetting robot that dispenses chemical reagents and sample solutions into an open-column resin bed for elemental separation. After the initial set up of resin columns, chemical reagents, and beakers for the separated chemical components, all separation procedures are automated. As many as ten samples can be eluted in parallel in a single automated run. Many separation procedures, such as radiogenic isotope ratio analyses for Sr and Nd, involve the use of multiple column separations with different resin columns, chemical reagents, and beakers of various volumes. COLUMNSPIDER completes these separations using multiple runs. Programmable functions, including the positioning of the micropipetter, reagent volume, and elution time, enable flexible operation. Optimized movements for solution take-up and high-efficiency column flushing allow the system to perform as precisely as when carried out manually by a skilled operator. Procedural blanks, examined for COLUMNSPIDER separations of Sr, Nd, and Pb, are low and negligible. The measured Sr, Nd, and Pb isotope ratios for JB-2 and Nd isotope ratios for JB-3 and BCR-2 rock standards all fall within the ranges reported previously in high-accuracy analyses. COLUMNSPIDER is a versatile tool for the efficient elemental separation of igneous rock samples, a process that is both labor intensive and time consuming.

  13. Single Variable and Multivariate Analysis of Remote Laser-Induced Breakdown Spectra for Prediction of Rb, Sr, Cr, Ba, and V in Igneous Rocks

    SciTech Connect

    Clegg, Samuel M; Wiens, Roger C.; Speicher, Elly A; Dyar, Melinda D; Carmosino, Marco L

    2010-12-23

    Laser-induced breakdown spectroscopy (LIBS) will be employed by the ChemCam instrument on the Mars Science Laboratory rover Curiosity to obtain UV, VIS, and VNIR atomic emission spectra of surface rocks and soils. LIBS quantitative analysis is complicated by chemical matrix effects related to abundances of neutral and ionized species in the resultant plasma, collisional interactions within plasma, laser-to-sample coupling efficiency, and self-absorption. Atmospheric composition and pressure also influence the intensity of LIBS plasma. These chemical matrix effects influence the ratio of intensity or area of a given emission line to the abundance of the element producing that line. To compensate for these complications, multivariate techniques, specifically partial least-squares regression (PLS), have been utilized to predict major element compositions (>1 wt.% oxide) of rocks, PLS methods regress one or multiple response variables (elemental concentrations) against multiple explanatory variables (intensity at each pixel of the spectrometers). Because PLS utilizes all available explanatory variable and eliminates multicollinearity, it generally performs better than univariate methods for prediction of major elements. However, peaks arising from emissions from trace elements may be masked by peaks of higher intensities from major elements. Thus in PLS regression, wherein a correlation coefficient is determined for each elemental concentration at each spectrometer pixel, trace elements may show high correlation with more intense lines resulting from optical emissions of other elements. This could result in error in predictions of trace element concentrations. Here, results of simple linear regression (SLR) and multivariate PLS-2 regression for determination of trace Rb, Sr, Cr, Ba, and V in igneous rock samples are compared. This study focuses on comparisons using only line intensities rather than peak areas to highlight differences between SLR and PLS.

  14. The Late Cretaceous igneous rocks of Romania (Apuseni Mountains and Banat): the possible role of amphibole versus plagioclase deep fractionation in two different crustal terranes

    NASA Astrophysics Data System (ADS)

    Vander Auwera, Jacqueline; Berza, Tudor; Gesels, Julie; Dupont, Alain

    2016-04-01

    We provide new whole-rock major and trace elements as well as 87Sr/86Sr and 143Nd/144Nd isotopic data of a suite of samples collected in the Late Cretaceous volcanic and plutonic bodies of the Apuseni Mts. (Romania) that belong to the Banatitic Magmatic and Metallogenic Belt, also called the Apuseni-Banat-Timok-Srednogorie belt. The samples define a medium- to high-K calc-alkaline differentiation trend that can be predicted by a three-step fractional crystallization process which probably took place in upper crustal magma chambers. Published experimental data indicate that the parent magma (Mg# = 0.47) of the Apuseni Mts. trend could have been produced by the lower crustal differentiation of a primary (in equilibrium with a mantle source) magma. The Late Cretaceous magmatic rocks of the Apuseni Mts. and Banat display overlapping major and trace element trends except that Sr is slightly lower and Ga is higher in the Apuseni Mts. parent magma. This difference can be accounted for by fractionating plagioclase-bearing (Apuseni Mts.) or amphibole-bearing (Banat) cumulates during the lower crustal differentiation of the primary magma to the composition of the parent magma of both trends. This, together with results obtained on the Late Cretaceous igneous rocks from the Timok area in Eastern Serbia, further suggests variation of the water content of the primary magma along and across the belt. The Apuseni Mts. versus the Banat samples display different isotopic compositions that likely resulted from the assimilation of two distinct crustal contaminants, in agreement with their emplacement in two separate mega-units of Alpine Europe.

  15. Tectonic setting of basic igneous and metaigneous rocks of Borborema Province, Brazil using multi-dimensional geochemical discrimination diagrams

    NASA Astrophysics Data System (ADS)

    Verma, Sanjeet K.; Oliveira, Elson P.

    2015-03-01

    Fifteen multi-dimensional diagrams for basic and ultrabasic rocks, based on log-ratio transformations, were used to infer tectonic setting for eight case studies of Borborema Province, NE Brazil. The applications of these diagrams indicated the following results: (1) a mid-ocean ridge setting for Forquilha eclogites (Central Ceará domain) during the Mesoproterozoic; (2) an oceanic plateau setting for Algodões amphibolites (Central Ceará domain) during the Paleoproterozoic; (3) an island arc setting for Brejo Seco amphibolites (Riacho do Pontal belt) during the Proterozoic; (4) an island arc to mid-ocean ridge setting for greenschists of the Monte Orebe Complex (Riacho do Pontal belt) during the Neoproterozoic; (5) within-plate (continental) setting for Vaza Barris domain mafic rocks (Sergipano belt) during the Neoproterozoic; (6) a less precise arc to continental rift for the Gentileza unit metadiorite/gabbro (Sergipano belt) during the Neoproterozoic; (7) an island arc setting for the Novo Gosto unit metabasalts (Sergipano belt) during Neoproterozoic; (8) continental rift setting for Rio Grande do Norte basic rocks during Miocene.

  16. Geochemistry of meta-igneous rocks from southern Ethiopia: a new insight into neoproterozoic tectonics of northeast Africa

    NASA Astrophysics Data System (ADS)

    Alene, Mulugeta; Barker, Andrew J.

    1997-04-01

    Utilising geochemical data, various discriminant diagrams have been employed to establish the magma type and original tectonic environment for some Neoproterozoic amphibolites, ultrabasic rocks and gabbros of the Moyale area, southern Ethiopia. The gneissic amphibolites are found to have mixed geochemical characteristics indicative of island arc and/or ocean ridge basalts with tholeiitic composition whereas the porphyritic amphibolites show alkalic features with no clear tectonic setting. The ultrabasic and gabbroic units of the Moyale area are described in terms of their relation with mantle melts and parental material. The majority of ultrabasics relate to a cumulate origin and the gabbroic rocks appear as more differentiated magma from the same source. The mainly dunite bodies in the eastern sub-area at Moyale probably represent refractory residues left after variable degree of partial melting of a periodotite mantle. It is concluded that the gneissic amphibolites were probably part of an accreting arc associated with closure of a pre-existing oceanic basin. The ultrabasic and gabbroic rocks (together with the porphyritic amphibolite) are considered to be remnants of oceanic crust.

  17. Testing the Mojave-Sonora megashear hypothesis: Evidence from Paleoproterozoic igneous rocks and deformed Mesozoic strata in Sonora, Mexico

    USGS Publications Warehouse

    Amato, J.M.; Lawton, T.F.; Mauel, D.J.; Leggett, W.J.; Gonzalez-Leon, C. M.; Farmer, G.L.; Wooden, J.L.

    2009-01-01

    U-Pb ages and Nd isotope values of Proterozoic rocks in Sonora, Mexico, indicate the presence of Caborca-type basement, predicted to lie only south of the Mojave-Sonora mega-shear, 40 km north of the postulated megashear. Granitoids have U-Pb zircon ages of 1763-1737 Ma and 1076 Ma, with ??Nd(t) values from +1.4 to -4.3, typical of the Caborca block. Lower Jurassic strata near the Proterozoic rocks contain large granitic clasts with U-Pb ages and ??Nd(t) values indistinguishable from those of Caborcan basement. Caborca-type basement was thus present at this location north of the megashear by 190 Ma, the depositional age of the Jurassic strata. The Proterozoic rocks are interpreted as parautochthonous, exhumed and juxtaposed against the Mesozoic section by a reverse fault that formed a footwall shortcut across a Jurassic normal fault. Geochronology, isotope geochemistry, and structural geology are therefore inconsistent with Late Jurassic megashear displacement and require either that no major transcurrent structure is present in Sonora or that strike-slip displacement occurred prior to Early Jurassic time. ?? 2009 The Geological Society of America.

  18. Sr-Nd-Pb isotope mapping of Mesozoic igneous rocks in NE China: Constraints on tectonic framework and Phanerozoic crustal growth

    NASA Astrophysics Data System (ADS)

    Guo, Feng; Fan, Weiming; Gao, Xiaofeng; Li, Chaowen; Miao, Laicheng; Zhao, Liang; Li, Hongxia

    2010-12-01

    New Sr-Nd-Pb isotope dataset of Mesozoic igneous rocks shows that the NE China can be subdivided into four Sr-Nd-Pb isotope provinces: (1) the northern Hinggan Mountains (NHM) region; (2) the southern Hinggan Mountain (SHM)-Yanji-Liaoyuan (YL) region; (3) the Zhangguangcai Range-Jiamusi (ZGJ) Block; and (4) the exotic Wandashan massif (WDM). The Wandashan massif contains Mesozoic (high-μ)-type oceanic island basalts (HIMU-OIBs) with highly radiogenic Pb isotopic compositions (e.g., 206Pb/ 204Pb(i) = 18.9-22.7), quite different from other regions that have moderately radiogenic Pb (i.e., 206Pb/ 204Pb(i)) is generally less than 18.6. These HIMU-OIBs also show negative Δ7/4 and Δ8/4 values, signatures of Southern Gondwanaland Continent. By contrast, the majority of Mesozoic igneous rocks in other areas of NE China have positive Δ7/4 and Δ8/4 values, akin to the Northern Laurasian Continent. Such isotopic variations were probably due to the enrichment processes mainly caused by Paleozoic Paleo-Asian ocean subduction and to some extent by subduction of the Paleo-Pacific Ocean since early Mesozoic. The mantle-derived rocks in the NHM region is characterized by moderately radiogenic Nd and Pb isotopic compositions (ɛ Nd(t) = -0.2 to + 3.6 and 206Pb/ 204Pb(i) = 18.3-18.6). Compared with the NHM region, the mantle-derived magmas in the SHM-YL region show wider Nd isotopic variation (ɛ Nd(t) = -1.1 to + 6.6) and less radiogenic Pb ( 206Pb/ 204Pb(i) = 18.1-18.4). Along the Hegenshan-Solonker suture distributes an early Cretaceous felsic magmatic belt with highly positive-ɛ Nd (ɛ Nd(t) = + 4.0 to + 5.9) and radiogenic Pb compositions ( 206Pb/ 204Pb(i) = 18.4-18.6), suggesting that it was not only an important Phanerozoic crustal growth belt but also a zone containing significant volume of pelagic sediments or their metamorphosed derivates. Adjacent to the Hengenshan ophiolite occurs a suite of andesites showing nonradiogenic Nd (ɛ Nd(t) = -10.5 to -6.3) and Pb ( 206

  19. Talking Rocks.

    ERIC Educational Resources Information Center

    Rice, Dale; Corley, Brenda

    1987-01-01

    Discusses some of the ways that rocks can be used to enhance children's creativity and their interest in science. Suggests the creation of a dramatic production involving rocks. Includes basic information on sedimentary, igneous, and metamorphic rocks. (TW)

  20. Deciphering igneous and metamorphic events in high-grade rocks of the Wilmington complex, Delaware: Morphology, cathodoluminescence and backscattered electron zoning, and SHRIMP U-Pb geochronology of zircon and monazite

    USGS Publications Warehouse

    Aleinikoff, J.N.; Schenck, W.S.; Plank, M.O.; Srogi, L.A.; Fanning, C.M.; Kamo, S.L.; Bosbyshell, H.

    2006-01-01

    High-grade rocks of the Wilmington Complex, northern Delaware and adjacent Maryland and Pennsylvania, contain morphologically complex zircons that formed through both igneous and metamorphic processes during the development of an island-arc complex and suturing of the arc to Laurentia. The arc complex has been divided into several members, the protoliths of which include both intrusive and extrusive rocks. Metasedimentary rocks are interlayered with the complex and are believed to be the infrastructure upon which the arc was built. In the Wilmingto n Complex rocks, both igneous and metamorphic zircons occur as elongate and equant forms. Chemical zoning, shown by cathodoluminescence (CL), includes both concentric, oscillatory patterns, indicative of igneous origin, and patchwork and sector patterns, suggestive of metamorphic growth. Metamorphic monazites are chemically homogeneous, or show oscillatory or spotted chemical zoning in backscattered electron images. U-Pb geochronology by sensitive high resolution ion microprobe (SHRIMP) was used to date complexly zoned zircon and monazite. All but one member of the Wilmington Complex crystallized in the Ordovician between ca. 475 and 485 Ma; these rocks were intruded by a suite of gabbro-to-granite plutonic rocks at 434 ?? Ma. Detrital zircons in metavolcanic and metasedimentary units were derived predominantly from 0.9 to 1.4 Ga (Grenvillian) basement, presumably of Laurentian origin. Amphibolite to granulite facies metamorphism of the Wilmington Complex, recorded by ages of metamorphic zircon (428 ?? 4 and 432 ?? 6 Ma) and monazite (429 ?? 2 and 426 ?? 3 Ma), occurred contemporaneously with emplacement of the younger plutonic rocks. On the basis of varying CL zoning patterns and external morphologies, metamorphic zircons formed by different processes (presumably controlled by rock chemistry) at slightly different times and temperatures during prograde metamorphism. In addition, at least three other thermal episodes are

  1. Partitioning large data sets: Use of statistical methods applied to a set of Russian igneous-rock chemical analyses

    NASA Astrophysics Data System (ADS)

    Hernández Encinas, L.

    1994-12-01

    A method of cluster analysis has been applied on the following ideas: (a) stabilizing the variances of the variables; (b) reducing the number of variables by principal component analysis; and (c) generating a moderate number of groups containing large numbers of samples and applying a method of cluster analysis to them. This method was applied to a large data set to divide it into groups of samples without taking into consideration their origin. The sample set available consists of 1271 rock chemical analyses from 37 Massifs in the Ural Mountains (Russia), which then were divided into 6 differentiated groups. Later, discriminant functions were calculated to assign new samples to the groups determined.

  2. Age and tectonic setting of subsurface plutonic rocks in south Alabama: Implications for igneous activity along the Alleghanian suture

    SciTech Connect

    Guthrie, G.M. ); Steltenpohl, M.G. . Dept. of Geology); Heatherington, A.L. . Dept. of Geology); Kunk, M.J. ); Defant, M.S. . Dept. of Geology); Salpas, P.A. )

    1994-03-01

    The proposed Alleghanian suture between ancestral North America and Suwannee terrane Gondwana crust trends east-west beneath coastal plain sediments from South Carolina to Alabama. Three distinct intrusive suites in south Alabama have been examined to determine their possible relationships with the suture. The first suite consists of rhyolite, andesite, andesitic breccia, and granodiorite and forms the stratigraphic base of the Suwannee terrane. Calc-alkaline metaluminous granodiorite yields a whole-rock depleted mantle Nd model age of 1,023 Ma, a U-Pb zircon crystallization age of 625 Ma, and a [sup 40]Ar/[sup 39]Ar cooling age (ca. 500 C) of ca. 612 Ma. The second suite comprises felsic granophyre, pyroxenite, and diabase. Metaluminous granophyre follows a calc-alkaline trend with pyroxenite. Trace element ratios (Ta/Yb and Rb/Yb+Ta) indicate a volcanic or syn-collisional arc environment. Biotite separates from granodiorite yield a [sup 40]Ar/[sup 39]Ar cooling age (ca. 300 C) of ca. 329 Ma. Pyroxenite and granophyre Nd model ages are 1,062 and 1,090 Ma, respectively. The third suite comprises high-iron quartz-normative tholeiitic diabase, gabbro, and basalt. These rocks have Ta/Yb and Rb/Yb+Ta ratios similar to within plate magmas, and are correlated with the Lower Jurassic North American diabase suite because of geochemical similarities and intrusive contacts with the Upper Triassic-Lower Jurassic Newark Group.

  3. Low Ni olivine in silica-undersaturated ultrapotassic igneous rocks as evidence for carbonate metasomatism in the mantle

    NASA Astrophysics Data System (ADS)

    Ammannati, Edoardo; Jacob, Dorrit E.; Avanzinelli, Riccardo; Foley, Stephen F.; Conticelli, Sandro

    2016-06-01

    Subduction drags a large amount of CO2 into the Earth's interior, which is partly returned to the atmosphere by arc volcanism. Processes involved in the recycling of subducted carbon within the upper mantle are mainly related to mineralogical transformation. Subducted CO2 may dramatically affect the equilibria among peridotitic minerals (olivine vs. pyroxenes) changing their stability fields and hence their modal abundances. This process is accompanied by a subduction-induced change in the budget of some incompatible trace and major elements (e.g., K, Ca, HFSE), whereas it has a minimal effect on the mass balance of compatible elements (e.g., Ni). We report trace elements in olivine in subduction-related mafic alkaline ultrapotassic rocks from Italy, which are used as a proxy to define mantle wedge mineralogy and metasomatic processes. Minor element concentrations, and in particular the high Li and low Ti of all the olivines, confirm a major role for recycled sediment in the generation of Italian ultrapotassic magmas. The distinct contents of Ni, Mn, and Ca in olivine reflect the bimodal character of silica-rich and silica-poor ultrapotassic Italian rocks and constrain two distinct mineralogical reactions between metasomatic agents and peridotite. Olivine chemistry from silica-saturated rocks reflects the reaction of silicate melts with the ambient mantle, with consequent consumption of olivine in favour of orthopyroxene. In contrast, the low-Ni, high-Mn/Fe of olivine crystallised from silica-undersaturated leucitites require a mantle source enriched in olivine (and clinopyroxene) compared to orthopyroxene, as a result of the interaction between the ambient peridotitic mantle and CaCO3-rich metasomatic agents. The change from silica-oversaturated lamproites to silica-undersaturated leucitites and thus the difference in the olivine composition is due to a change in composition of the subducting sediment from pelitic to carbonate-rich. The results of this study

  4. Sr-Nd-Pb isotopic compositions of the lower crust beneath northern Tarim: insights from igneous rocks in the Kuluketage area, NW China

    NASA Astrophysics Data System (ADS)

    Zhang, Yan; Wei, Xun; Xu, Yi-Gang; Long, Xiao-Ping; Shi, Xue-Fa; Zhao, Jian-Xin; Feng, Yue-Xing

    2016-09-01

    The composition of lower crust of the Tarim Craton in NW China is essential to understand the petrogenesis of the ~290-275 Ma Tarim basalts and associated intermediate-felsic rocks. However, it remains poorly constrained because extremely sparse granulite terrains or granulite xenoliths have been found in the Tarim Craton. New trace element and Sr-Nd-Pb isotopic data are reported for the Neoarchean and Neoproterozoic igneous rocks widely distributed in the northern margin of the Tarim Craton. The Neoarchean granitic gneisses show fractionated REE (rare earth element) patterns [(La/Yb) N = 12-58, YbN = 10.6-36] with pronounced negative Nb-Ta and Ti anomalies. These features, together with negative ɛNdi (-0.7 to -3.2) suggest that they were derived from melting of mafic lower crust. The Neoproterozoic biotite granodiorites are strongly depleted in HREE with (La/Yb) N up to 55. They are characterized by high Sr (671-789 ppm) but very low Y (7.10-8.06 ppm) and Yb contents (0.47-0.58 ppm), showing typical features of adakitic rocks. The samples with different SiO2 contents display identical 87Sr/86Sri (0.7101-0.7103), ɛNdi (-14.1 to -15.7) and Pb isotopes (208Pb/204Pbi = 36.94-37.07). These features together with arc-like trace element patterns suggest that they were derived from melting of thickened lower crust. In comparison, the Neoproterozoic hornblende-biotite granodiorites have similar trace element compositions except for weaker depletion in HREE and have lower 87Sr/86Sri (0.7078) and initial Pb isotopes, and higher ɛNdi (-12.3 to -12.7). This suggests that they were formed by melting of old lower continental crust at a shallower depth than the biotite granodiorites. These rocks were derived from the lower crust, thus providing valuable information on the nature of the lower crust beneath northern Tarim. Combined with published data, the 87Sr/86Sri, ɛNdi, 206Pb/204Pbi and ɛHfi of the northern Tarim lower crust ranges from 0.7055 to 0.7103, from -12 to -17

  5. Chemical data and variation diagrams of igneous rocks from the Timber Mountain-Oasis Valley Caldera Complex, southern Nevada

    USGS Publications Warehouse

    Quinlivan, W.D.; Byers, F.M.

    1977-01-01

    Silica variation diagrams presented here are based on 162 chemical analyses of tuffs, lavas, and intrusives, representative of volcanic centers of the Timber Mountain-Oasis Valley caldera complex and cogenetic rocks of the Silent Canyon ca1dera. Most of the volcanic units sampled are shown on the U.S. Geological Survey geologic map of the Timber Mountain caldera area (I-891) and are described in U.S. Geological Survey Professional Paper 919. Early effusives of the complex, although slightly altered, are probably chemically, and petrographically, more like the calc-alkalic Fraction Tuff (Miocene) of the northern Nellis Air Force Base Bombing and Gunnery Range to the north, whereas effusives of later Miocene age, such as the Paintbrush and Timber Mountain Tuffs, are alkali-calcic.

  6. Stable isotope studies of metasomatic Ca-Fe-Al-Si skarns and associated metamorphic and igneous rocks, Osgood Mountains, Nevada

    USGS Publications Warehouse

    Taylor, B.E.; O'Neil, J.R.

    1977-01-01

    Garnet-pyroxene skarns were formed 90 m.y. B.P. in the Osgood Mountains at or near contacts of grandiorite with calcareous rocks of the Cambrian Preble Formation. The metasomatic replacement followed contact metamorphic recrystallization of the Preble. The sources, temperature, and variation in H2O/CO2 ratios of the metasomatic fluid are interpreted from 269 analyses of oxygen, carbon, hydrogen, and sulfur isotopes in whole rocks, minerals and inclusion fluids. Skarns formed in three mineralogical stages. Oxygen isotope data indicate that temperatures during the crystallization of garnet, pyroxene and wollastonite (Stage I) were least 550 ?? C, and that the metasomatic fluid had an {Mathematical expression} ??? 0.035 in the massive skarns, and ??? 0.12 in vein skarns up to 3 cm thick. Pore fluids in isotopic equilibrium with garnet in calc-silicate metamorphic rocks, on the other hand, had {Mathematical expression} ??? 0.15. The metasomatic fluids of Stage I were derived primarily from the crystallizing magma. The isotopic composition of magmatic water was ??18O =+9.0, ??D= -30 to -45. Oxygen isotope temperatures of greater than 620 ?? C were determined for the granodiorite. Isotopic and chemical equilibria between mineral surfaces and the metasomatic fluid were approached simultaneously in parts of the skarn several meters or more apart, while isotopic and chemical disequilibria (i.e. zoning) have been preserved between 20 to 40 ??m-thick zones in grandite garnet. More Fe-, or andradite-rich garnet crystallized in more H2O-rich C-O-H fluids ( {Mathematical expression} ??? 0.01) than present with grossularite-rich garnet ( {Mathematical expression}??? 0.035). Stage II was marked by the replacement of garnet and pyroxene by quartz, amphibole, plagioclase, epidote, magnetite, and calcite. Many of the replacement reactions took place over a relatively narrow range in temperature (480-550 ?? C), as indicated by 18O fractionations between quartz and amphibole. Meteoric

  7. Orogeny processes of the western Jiangnan Orogen, South China:Insights from Neoproterozoic igneous rocks and a deep seismic profile

    NASA Astrophysics Data System (ADS)

    Su, Jinbao; Dong, Shuwen; Zhang, Yueqiao; Li, Yong; Chen, Xuanhua; Ma, Licheng; Chen, Jiansheng

    2017-01-01

    The Jiangnan Orogen is a collisional suture belt between the Yangtze and Cathaysia Blocks in South China, with many unanswered questions regarding its tectonic evolution. Using the basement structure of the Jiangnan Orogen, we investigate the granite and dacite exposed along the western Jiangnan Orogen and present new LA-ICP-MS zircon U-Pb ages, Hf isotopes, and whole rock geochemistry data. The results suggest that the granite plutons belong to the calc-alkaline series and are typical S-type granites. It yields a mean U-Pb age of 854 ± 2 Ma, which is determined from the core of zircon and possibly inherited from its source or wall rocks. The initial emplacement age of granite may be 826-805 Ma, whereas the dacites yield an age of 805 ± 1.6 Ma and belong to the shoshonite series. The initial Hf-isotope ratios (176Hf/177Hf) in the granite sample are mostly negative εHf(t), with a few of positive value with 1.38-1.6 Ga TDM and 1.67-2.06 Ga TDM2, whereas the dacite samples have mostly positive εHf(t), with a 0.78-1.6 Ga TDM and 0.83-2.2 Ga TDM2t. A comparison of the εHf(t) and TDM2t with the corresponding intruded strata, helps illustrate the origin of the magma and the finals stages ofcollision. Based on our results, we conclude that the western Jiangnan Orogen was a back-arc foreland basin that developed on the margin of the Yangtze continent and collided with the Cathaysia Block, forming a continent-arc-continent accretionary orogeny between 860 and 800 Ma.

  8. Acid-neutralizing potential of minerals in intrusive rocks of the Boulder batholith in northern Jefferson County, Montana

    USGS Publications Warehouse

    Desborough, George A.; Briggs, Paul H.; Mazza, Nilah; Driscoll, Rhonda

    1998-01-01

    Experimental studies show that fresh granitic rocks of the Boulder batholith in the Boulder River headwaters near Basin, Montana have significant acid-neutralizing potential and are capable of neutralizing acidic water derived from metal-mining related wastes or mine workings. Laboratory studies show that in addition to the acidneutralizing potential (ANP) of minor amounts of calcite in these rocks, biotite, tremolite, and feldspars will contribute significantly to long-term ANP. We produced 0.45 micrometer-filtered acidic (pH = 2.95) leachate for use in these ANP experiments by exposing metal-mining related wastes to deionized water in a waste:leachate ratio of 1:20. We then exposed these leachates to finely-ground and sized fractions of batholith rocks, and some of their mineral fractions for extended and repeated periods, for which results are reported here. The intent was to understand what reactions of metal-rich acidic water and fresh igneous rocks would produce. The reactions between the acidic leachates and the bulk rocks and mineral fractions are complex. Factors such as precipitation of phases like Fe-hydroxides and Alhydroxides and the balance between dissolved cations and anions that are sulfate dominated complicate analysis of the results. Research by others of acid neutralization by biotite and tremolite attributed a rise in pH to proton (H+) adsorption in sites vacated by K, Mg, and Ca. Destruction of the silicate framework and liberation of associated structural hydroxyl ions may contribute to ANP. Studies by others have indicated that the conversion of biotite to a vermiculite-type structure by removal of K at a pH of 4 consumes about six protons for every mole of biotite, but at a pH of 3 there is pronounced dissolution of the tetrahedral lattice. The ANP of fresh granitic rocks is much higher than anticipated. The three bulk Boulder igneous rock samples studied have minimum ANP equivalent to about 10-14 weight percent calcite. This ANP is in

  9. 40Ar/39Ar geochronology of hypabyssal igneous rocks in the Maranon Basin of Peru - A record of thermal history, structure, and alteration

    USGS Publications Warehouse

    Prueher, L.M.; Erlich, R.; Snee, L.W.

    2005-01-01

    Hypabyssal andesites and dacites from the Balsapuerto Dome in the Mara?on Basin of Peru record the thermal, tectonic, and alteration history of the area. The Mara?on Basin is one of 19 sub-Andean foreland basins. The hypabyssal rocks in the Balsapuerto Dome are one of four known occurrences of subvolcanic rocks along the deformation front in Peru. This dome is a potential petroleum structural trap. Petroleum seeps near the dome indicate that a source for the petroleum is present, but the extent and amount of petroleum development is unknown. The Balsapuerto hypabyssal rocks are plagioclase-, hornblende-, pyroxene-phyric andesites to dacites. Some parts of the dome are pervasively altered to a hydrothermal assemblage of quartz-sericite-pyrite. 40Ar/39Ar geochronology shows that thermal activity related to emplacement of these subvolcanic rocks took place between 12-10 Ma, subsequent to the major periods of Andean folding and faulting, previously assumed to have occurred about 9 Ma. Eleven argon mineral age-spectrum analyses were completed. Argon apparent ages on amphibole range from 12.7 to 11.6 Ma, and the age spectra are simple, which indicates that the ages are very close to emplacement ages. Potassium feldspar yields an argon age spectrum ranging in age from 12.5 to 11.4 Ma, reflecting the period during which the potassium feldspar closed to argon diffusion between the temperature range of 350?C to about 150?C; thus the potassium feldspar age spectrum reflects a cooling profile throughout this temperature range. This age range is consistent with ages of emplacement for the entire igneous complex indicating that an increased thermal state existed in the area for at least 1.0 m.y. Combined with the coexisting hornblende age, this rock cooled from ~580?C to ~150?C in ~1.2 m.y. resulting in an average cooling rate of 358?C /m.y. White mica, or sericite, formed as a later alteration phase associated with quartz- sericite- pyrite and propylitic alteration in some

  10. Geochronology and Geochemistry of Igneous Rocks from the Laoshankou District, North Xinjiang: Implications for the Late Paleozoic Tectonic Evolution and Metallogenesis of East Junggar

    NASA Astrophysics Data System (ADS)

    Liang, Pei; Chen, Huayong; Hollings, Pete; Wu, Chao; Xiao, Bing; Bao, Zhiwei; Xu, Deru

    2016-12-01

    arc. The northern margin of East Junggar was related to the southward subduction of the Kuerti-Erqis Ocean (a branch of the Paleo-Asian Ocean) between the Altay and the Dulate arcs in this period, consistent with the presence of Nb-enriched basalts and boninites in the north of the Dulate arc and the island arc rather than back arc setting of the igneous rocks in the Laoshankou district. For metallogenesis in the northern margin of East Junggar, arc-related Fe-Cu-Au and porphyry Cu mineralization was dominated. There is large potential to find several Late Paleozoic arc-related Fe-Cu-Au mineralizations in North Xinjiang.

  11. Chemical composition of igneous rocks expressed by means of diagrams, with reference to rock classification on a quantitative chemico-mineralogical basis

    USGS Publications Warehouse

    Iddings, J.P.

    1903-01-01

    The value of graphical methods for expressing relative quantities has been well established in all kinds of statistical exposition and discussion. Their use in conveying definite conceptions of relative quantities of chemical and mineral components of rocks is becoming more and more frequent, and the value of the results in some cases can not be overestimated. This is especially true when a series or group of rocks is being considered. The intricate variations in the amounts of numerous mineral components, or of chemical components, baffle most attempts to comprehend their interrelationships by simple contemplation or by study of the numbers in which they may be expressed. Many facts and relations are overlooked which arc readily observed when diagrams are used to represent numerical figures. Moreover, visual memory is sufficiently developed in most persons to enable them to carry in mind simple geometrical forms, where it does not permit them to recollect manifold assemblages of oft-repeated numbers. Mental impressions of simple diagrams are, therefore, more definite and lasting and enable the student to store up a much greater amount of quantitative data than he could otherwise acquire.

  12. Subduction- and non-subduction-related igneous rocks in the Central European Variscides: geochemical and Nd isotope evidence from the Kłodzko Metamorphic Complex, Polish Sudetes

    NASA Astrophysics Data System (ADS)

    Kryza, Ryszard; Mazur, Stanisław; Pin, Christian

    2003-11-01

    The Kłodzko Metamorphic Complex (KMC) in the Central Sudetes is a composite outcrop of pre-Upper Devonian metasedimentary and metaigneous rocks, formed of several thrust units. The metaigneous rocks are geochemically diversified, and were interpreted to reflect a complex geodynamic setting of emplacement. The association of large amounts of felsic and mafic rocks is reminiscent of the model of Cambro-Ordovician bimodal, rift-related suites developed along the northern periphery of Gondwana. However, the felsic rocks are potash-poor, calc-alkaline in character, while the associated mafic rocks are, in part, metagabbros and cumulates resembling N-MORB, which is consistent with neither typical ensialic rift nor evolved MOR tectonic environments. Combined with published data, our new geochemical and Nd isotope results show that the metabasic rocks of the northeastern part of the KMC, not associated with felsic volcanics, are of within-plate type, with an ɛNd 400 (assuming approximate youngest possible Silurian/Devonian age) of +6.8, typical of magmas derived from time-integrated depleted mantle sources. The metagabbros of the southwestern part of the KMC (associated with felsic rocks) range from slightly enriched to depleted rocks, and their ɛNd 560 (assuming a Neoproterozoic age, K. Turniak, personal communication) scatters from +2.2 to +8.6, suggesting that hybrid sources and/or variable degrees of crustal contamination of a strongly depleted mantle source were involved. The intermediate and acidic rocks are peraluminous to metaluminous rhyolites, rhyodatites/dacites, and andesites (and volcaniclastics), with Na 2O > K 2O and large negative anomalies of Nb, Sr, and Ti. Their highly variable, but distinctly positive, ɛNd 560 values (from +2.9 to +8.6, mostly clustered around +5.5) overlap those measured in the associated metagabbros, thereby substantiating close genetic relationships. Metarhyolites produced by crustal melting are conspicuously missing. A

  13. Carbonate- and silicate-rich globules in the kimberlitic rocks of northwestern Tarim large igneous province, NW China: Evidence for carbonated mantle source

    NASA Astrophysics Data System (ADS)

    Cheng, Zhiguo; Zhang, Zhaochong; Santosh, M.; Hou, Tong; Zhang, Dongyang

    2014-12-01

    We report carbonate- and silicate-rich globules and andradite from the Wajilitage kimberlitic rocks in the northwestern Tarim large igneous province, NW China. The carbonate-rich globules vary in size from 1 to 3 mm, and most have ellipsoidal or round shape, and are composed of nearly pure calcite. The silicate-rich globules are elliptical to round in shape and are typically larger than the carbonate-rich globules ranging from 2 to several centimeters in diameter. They are characterized by clear reaction rims and contain several silicate minerals such as garnet, diopside and phlogopite. The silicate-rich globules, reported here for the first time, are suggested to be related to the origin of andradite within the kimberlitic rocks. Our results show that calcite in the carbonate-rich globules has a high XCa (>0.97) and is characterized by extremely high concentrations of the total rare earth elements (up to 1500 ppm), enrichment in Sr (8521-10,645 ppm) and LREE, and remarkable depletion in Nd, Ta, Zr, Hf and Ti. The calcite in the silicate-rich globules is geochemically similar to those in the carbonate-rich globules except the lower trace element contents. Garnet is dominantly andradite (And59.56-92.32Grs5.67-36.03Pyr0.36-4.61Spe0-0.33) and is enriched in light rare earth elements (LREEs) and relatively depleted in Rb, Ba, Th, Pb, Sr, Zr and Hf. Phlogopite in the silicate-rich globules has a high Mg# ranging from 0.93 to 0.97. The composition of the diopside is Wo45.82-51.39En39.81-49.09Fs0.88-0.95 with a high Mg# ranging from 0.88 to 0.95. Diopside in the silicate-rich globules has low total rare earth element (REE) contents (14-31 ppm) and shows middle REE- (Eu to Gd), slight light REE- and heavy REE-enrichment with elevated Zr, Hf and Sr contents and a negative Nb anomaly in the normalized diagram. The matrix of the kimberlitic rocks are silica undersaturated (27.92-29.31 wt.% SiO2) with low Al2O3 (4.51-5.15 wt.%) and high CaO (17.29-17.77 wt.%) contents. The

  14. Lignor process for acidic rock drainage treatment.

    PubMed

    Zhuang, J M; Walsh, T

    2004-09-01

    The process using lignosulfonates for acidic rock drainage (ARD) treatment is referred to as the Lignor process. Lignosulfonates are waste by-products produced in the sulfite pulping process. The present study has shown lignosulfonates are able to protect lime from developing an external surface coating, and hence to favor its dissociation. Further, the addition of lignosulfonates to ARD solutions increased the dotting and settling rate of the formed sludge. The capability of lignosulfonates to form stable metal-lignin complexes makes them very useful in retaining metal ions and thus improving the long-term stability of the sludge against leaching. The Lignor process involves metal sorption with lignosulfonates, ARD neutralization by lime to about pH 7, pH adjustment with caustic soda to 9.4 - 9.6, air oxidation to lower the pH to a desired level, and addition of a minimum amount of FeCl3 for further removal of dissolved metals. The Lignor process removes all concerned metals (especially Al and Mn) from the ARD of the Britannia Mine (located at Britannia Beach, British Columbia, Canada) to a level lower than the limits of the B.C. Regulations. Compared with the high-density sludge (HDS) process, the Lignor process has many advantages, such as considerable savings in lime consumption, greatly reduced sludge volume, and improved sludge stability.

  15. Copper isotope variations of copper-rich minerals in seafloor hydrothermal deposits and igneous rocks, measured by a femtosecond LA-MC-ICP-MS

    NASA Astrophysics Data System (ADS)

    Ikehata, K.; Ishibashi, J.; Suzuki, R.; Hirata, T.

    2013-05-01

    In recent years, the copper isotope systematics has seen an increased interest as a potential tool for understanding copper sources and geochemical processes of copper transport and deposition in ore-forming systems. The copper isotope variations of primary and secondary copper-rich minerals from modern (Mariana Trough) and ancient (Besshi-type and Kuroko-type volcanogenic massive sulfide deposits, Japan) seafloor hydrothermal deposits have been analyzed by a femtosecond-pulsed laser ablation multiple collector inductively coupled plasma mass spectrometry (fs-LA-MC-ICP-MS). The δ65Cu (where δ65Cu = [(65Cu/63Cu)sample/ (65Cu/63Cu)NIST-SRM976-1] × 1000) values of copper-rich sulfide minerals of chimney samples from active seafloor hydrothermal deposits are significantly large (δ65Cu = -0.7 to 4.0‰) compared to those of copper-rich minerals in ancient submarine hydrothermal deposits (δ65Cu = -0.3 to 0.4‰; e.g., Ikehata et al., 2011) and in igneous rocks (δ65Cu = -0.3 to 0.3‰; e.g., Ikehata et al., 2012). These large copper isotopic variations in the chimney samples are most likely explained in terms of a redox-controlled isotope fractionation during hydrothermal reworking of copper sulfides below sea floor or alteration of primary hydrothermal copper sulfides by seawater, involving the preferential incorporation of heavy copper isotopes in secondary Cu(II) solutions. These results also suggest that sub-seafloor recrystallization and metamorphic reequilibration may have reduced the original range of copper isotopes. Secondary malachite (δ65Cu = 2.6 to 3.0‰) and native copper (δ65Cu = 1.4 to 1.7‰) in the Besshi-type deposits have heavier copper isotopic values compared to precursor copper-rich minerals. These variations are mainly due to isotope fractionations during redox reactions (weathering) at low temperatures involving the preferential incorporation of heavy copper isotopes in secondary Cu(II) solutions.

  16. Acid rock drainage and climate change

    USGS Publications Warehouse

    Nordstrom, D.K.

    2009-01-01

    Rainfall events cause both increases and decreases in acid and metals concentrations and their loadings from mine wastes, and unmined mineralized areas, into receiving streams based on data from 3 mines sites in the United States and other sites outside the US. Gradual increases in concentrations occur during long dry spells and sudden large increases are observed during the rising limb of the discharge following dry spells (first flush). By the time the discharge peak has occurred, concentrations are usually decreased, often to levels below those of pre-storm conditions and then they slowly rise again during the next dry spell. These dynamic changes in concentrations and loadings are related to the dissolution of soluble salts and the flushing out of waters that were concentrated by evaporation. The underlying processes, pyrite oxidation and host rock dissolution, do not end until the pyrite is fully weathered, which can take hundreds to thousands of years. These observations can be generalized to predict future conditions caused by droughts related to El Ni??o and climate change associated with global warming. Already, the time period for dry summers is lengthening in the western US and rainstorms are further apart and more intense when they happen. Consequently, flushing of inactive or active mine sites and mineralized but unmined sites will cause larger sudden increases in concentrations that will be an ever increasing danger to aquatic life with climate change. Higher average concentrations will be observed during longer low-flow periods. Remediation efforts will have to increase the capacity of engineered designs to deal with more extreme conditions, not average conditions of previous years.

  17. A multi-isotope approach to understanding the evolution of Cenozoic magmatism in the northeastern Basin and Range: Results from igneous rocks in the Albion-Raft River-Grouse Creek metamorphic core complex

    NASA Astrophysics Data System (ADS)

    Konstantinou, A.; Strickland, A.; Miller, E. L.

    2012-12-01

    Deep crustal rocks exposed by extensional processes in metamorphic core complexes provide a unique opportunity to address the magmatic and isotopic evolution of the crust and assess the relative crust versus mantle contributions in Cenozoic igneous rocks exposed in the complexes. The Albion-Raft River-Grouse Creek metamorphic core complex exposes mid-crustal rocks that resided at depths of ~15-20 km before the onset of Cenozoic extension. Three major Cenozoic magmatic events are represented in the complex and have been studied using multiple isotopic systems (whole rock Sr and Nd coupled with the Oxygen isotopes in zircon). These three major events are: (1) 42-31 Ma intrusion of a composite plutonic complex of calc-alkaline composition that intrudes both upper crustal rocks (~5-10 km depth) and deeper rocks. (2) A 32-25 Ma plutonic complex, with evolved calc-alkaline composition that intruded in the middle crust (~12-15 km depth), and (3) A 10-8 Ma bimodal (basalt-rhyolite) suite of volcanic rocks that contain high-T anhydrous mineral assemblages erupted across the complex. The pre-extensional crust consisted of an upper crust composed primarily of Neoproterozoic through Triassic metasedimentary rocks (schist and quartzite at its base and limestone at its top). The middle crust consists of late Archean orthogneiss with evolved composition (metamorphosed peraluminous granite) with average 87Sr/86Sr40~0.800, ɛNd40~ -43.4 and δ18Ozirc ~5.7‰. The lower crust is inferred to have been composed of Precambrian intermediate composition igneous rocks with average 87Sr/86Sr40~0.750, ɛNd40~ -37.5 and δ18Ozirc ~5.9‰, and Precambrian mafic rocks with average 87Sr/86Sr40~0.717, ɛNd40~ -25 and δ18Ozirc ~7.0‰. Existing and new data indicate that the 42-31 Ma upper crustal plutonic complex ranges in isotopic composition from 87Sr/86Sri=0.709-0.712, ɛNdi=-15 to -25 and δ18Ozirc 4.7-6.5‰. The composition of the 32-25 Ma middle crustal plutonic complex ranges from 87Sr

  18. PASSIVE TREATMENT OF ACID ROCK DRAINAGE FROM A SUBSURFACE MINE

    EPA Science Inventory

    Acidic, metal-contaminated drainages are a critical problem facing many areas of the world. Acid rock drainage results when metal sulfide minerals, particularly pyrite, are oxidized by exposure to oxygen and water. The deleterious effects of these drainages on receiving streams a...

  19. The importance of late- and post-orogenic crustal growth in the early Proterozoic: Evidence from Sm-Nd isotopic studies of igneous rocks in the Makkovik Province, Canada

    NASA Astrophysics Data System (ADS)

    Kerr, Andrew; Fryer, Brian J.

    1994-07-01

    Sm-Nd isotopic studies suggest that large tracts of 1900-1700 Ma old crust in Laurentia-Baltica is of 'juvenile' origin. This crust has generally been ascribed to arc magmatism, sustained over long periods, and most conceptual models for crustal growth emphasize this process. The late- to post-orogenic granitoid rocks that areally dominate many ancient orogenic belts are commonly viewed as anatectic derivatives of the earlier arc-type crust. However, in regions of short crustal residence, the time resolution of isotopic tracers, such as the Sm-Nd system, does not permit discrimination between this model and continued growth of the crust during post-orogenic magmatism. The relative contributions of recycled crust and new, mantle-derived material in late- to post-orogenic magmas can only be assessed where they also transect much older crustal blocks. The Nd isotopic signatures of 1800-1720 Ma igneous suites in the Makkovik Province define such a boundary between an Archean craton and a juvenile Proterozoic domain. In the juvenile domain, the Nd signatures of most igneous suites are equivocal (initial epsilon(sub Nd) = 0 to +2), and they could be anatectic derivatives of slightly older orthogneisses; however, addition of new, mantle-derived material is documented by 'A-type' granites with initial epsilon(sub Nd) up to +4. In the cratonic domain, temporally and compositionally equivalent igneous suites mostly have initial epsilon(sub Nd) of -7 to -3, significantly above local Archean basement, which has epsilon(sub Nd) of -15 at 1800 Ma. Conservative calculations suggest that most of these suites contain more than 50% new, mantle-derived material. These results suggest significant crustal growth via late-stage magmatism, and direct interaction of mantle-derived magmas and lower crustal rocks. In contrast, 1650 Ma igneous suites lack clear systematic variation in epsilon(sub Nd), and are interpreted as representing crustal growth via later, distal, arc-type magmatism

  20. Zircon U-Pb dating, geochemistry and Sr-Nd-Pb-Hf isotopes of the Wajilitag alkali mafic dikes, and associated diorite and syenitic rocks: Implications for magmatic evolution of the Tarim large igneous province

    NASA Astrophysics Data System (ADS)

    Zou, Si-Yuan; Li, Zi-Long; Song, Biao; Ernst, Richard E.; Li, Yin-Qi; Ren, Zhong-Yuan; Yang, Shu-Feng; Chen, Han-Lin; Xu, Yi-Gang; Song, Xie-Yan

    2015-01-01

    The Early Permian Tarim large igneous province (Tarim LIP) consists mainly of basaltic lavas, mafic-ultramafic intrusions including dikes and, syenite bodies in the Tarim Basin, NW China. A major unit of the Tarim LIP, the Wajilitag intrusive complex, consists of olivine pyroxenite, clinopyroxenite and gabbro units (from bottom to top), diorite and syenite rocks occurred in the upper part of the complex and alkali mafic dikes intrude the clinopyroxenite phase. Here we report the zircon U-Pb age and Hf isotopes, geochemical characteristics and Sr-Nd-Pb isotopic data of the alkali mafic dikes, and diorite, aegirine-nepheline syenite and syenite porphyry units in the Wajilitag intrusive complex. Zircons from the diorite and alkali mafic rocks yield concordant crystallization ages of 275.2 ± 1.2 Ma and 281.4 ± 1.7 Ma, respectively. The diorite and syenitic rocks in Wajilitag area have a narrow range of SiO2 contents (51.9-57.3 wt.%), and are enriched in total alkalis (Na2O + K2O = 8.3-14.3 wt.%), among which the aegirine-nepheline syenite and syenite porphyry have the geochemical affinity of A-type granites. The alkali mafic rocks and syenitic rocks have high Al2O3 (19.4-21.1 wt.%), Zr, Hf, Ba contents, total rare earth element abundances and LREE/HREE ratios and low Mg# value, K, P and Ti contents. Diorites have lower Al2O3 contents, total REE abundances and LREE/HREE ratios and higher Mg# values than the alkali mafic rocks and syenitic rocks. The diorites and syenitic rocks have low initial 87Sr/86Sr ratios (0.7034-0.7046), and high εNd(t) values (0.1-4.1) and zircon εHf(t) values (- 0.9-4.4). All the diorites and syenitic rocks show the 206Pb/204Pb ratios ranging of 18.0-19.5, 207Pb/204Pb of 15.4-15.6 and 208Pb/204Pb of 38.0-39.9. Sr-Nd isotopic ratios indicate a FOZO-like mantle source for the diorite and syenitic rocks, similar to that of the mafic-ultramafic rocks in the Wajilitag complex. In contrast, zircon Hf isotopes of basalt and syenite elsewhere in the

  1. Igneous Graphite in Enstatite Chondrites

    NASA Technical Reports Server (NTRS)

    Rubin, Alan E.

    1997-01-01

    Igneous graphite. a rare constituent in terrestrial mafic and ultramafic rocks. occurs in three EH and one EL enstatite chondrite impact-melt breccias as 2-150 Ilm long euhedrallaths. some with pyramidal terminations. In contrast. graphite in most enstatite chondrites exsolved from metallic Fe-Ni as polygonal. rounded or irregular aggregates. Literature data for five EH chondrites on C combusting at high temperatures show that Abee contains the most homogeneous C isotopes (i.e. delta(sup 13)C = -8.1+/-2.1%); in addition. Abee's mean delta(sup l3)C value is the same as the average high-temperature C value for the set of five EH chondrites. This suggests that Abee scavenged C from a plurality of sources on its parent body and homogenized the C during a large-scale melting event. Whereas igneous graphite in terrestrial rocks typically forms at relatively high pressure and only moderately low oxygen fugacity (e.g., approx. 5 kbar. logfO2, approx. -10 at 1200 C ). igneous graphite in asteroidal meteorites formed at much lower pressures and oxygen fugacities.

  2. Geochronological data of igneous and metamorphic rocks from the Xing'an-Mongolia Orogenic Belt of the eastern Central Asian Orogenic Belt: implications for the final closure of the Paleo-Asian Ocean

    NASA Astrophysics Data System (ADS)

    Guosheng, Wang; Chen, Wu; Cheng, Chen; Zhiguang, Zhou; Changfeng, Liu; Tian, Jiang

    2017-03-01

    In order to better constrain the evolution of the Xing'an-Mongolia Orogenic Belt and the resulting closure of the Paleo-Asian Ocean, we conducted an integrated investigation involving U-Pb dating of igneous and detrital zircon and a synthesis of existing work across the Erdaojing and Ondor Sum complexes in the eastern segment of the Central Asian Orogenic Belt. Geochronological analysis revealed a different tectonic setting between the Ondor Sum complex (Tulinkai area) and the Erdaojing accretion complex, as detrital zircon U-Pb analysis identified different major age provenances: (1) the Precambrian basement of the North China Craton and Paleozoic Bainaimiao Arc along the northern margin of North China to the south are the provenance rocks of the schists in the Tulinkai area, and (2) the Precambrian basement of the Xilinhot complex and Paleozoic Baolidao arc to the north are the provenance rocks of the schists in the Erdaojing area. We infer that the existence of the ocean between the above two regions in the late of Early Paleozoic in accordance with the result of this study. Furthermore, a comparison of the youngest age population in the intruded-diorite rock and metasedimentary rocks with U-Pb ages implies that the final closure of the Paleo- Asian Ocean along the Solonker Suture Zone most likely occurred in the period between 239 and 222 Ma (Late Paleozoic-Triassic).

  3. Early-Middle Paleozoic subduction-collision history of the south-eastern Central Asian Orogenic Belt: Evidence from igneous and metasedimentary rocks of central Jilin Province, NE China

    NASA Astrophysics Data System (ADS)

    Pei, Fu-Ping; Zhang, Ying; Wang, Zhi-Wei; Cao, Hua-Hua; Xu, Wen-Liang; Wang, Zi-Jin; Wang, Feng; Yang, Chuan

    2016-09-01

    To constrain the Early-Middle Paleozoic tectonic evolution of the south-eastern segment of the Central Asian Orogenic Belt (CAOB), we undertook zircon U-Pb dating and analyzed major and trace elements and zircon Hf isotope compositions of Late Cambrian to Middle Devonian igneous and metasedimentary rocks in central Jilin Province, NE China. LA-ICP-MS zircon U-Pb dating indicates that the Early-Middle Paleozoic magmatism in central Jilin Province can be divided into four episodes: Late Cambrian (ca. 493 Ma), Middle Ordovician (ca. 467 Ma), Late Ordovician-Early Silurian (ca. 443 Ma), and Late Silurian-Middle Devonian (425-396 Ma). The progression from subduction initiation to maturity is recorded by Late Cambrian low-K tholeiitic meta-diabase, Middle Ordovician medium-K calc-alkaline pyroxene andesite, and Late Ordovician to Early Silurian low-K tonalite, which all have subduction-related characteristics and formed in an evolving supra-subduction zone setting. Late Silurian to Middle Devonian calc-alkaline igneous rocks, with the lithological association of granodiorite, monzogranite, rhyolite, dacite, and trachydacite, show progressively increasing K2O contents from medium K to shoshonite series. Furthermore, the Early-Middle Devonian monzogranites are characterized by high K2O, Sr/Y, and [La/Yb]N values, indicating they were generated by the melting of thickened lower crust. These results suggest a transition from subduction to post-orogenic setting during the Late Silurian-Middle Devonian. Our interpretation is supported by the maximum age of molasse deposition in the Zhangjiatun member of the Xibiehe Formation. Overall, we suggest that Late Cambrian tholeiitic meta-diabase, Middle Ordovician pyroxene andesite, and Late Ordovician-Early Silurian tonalite formed above the northward-subducting and simultaneously seaward-retreating of Paleo-Asian Ocean plate. Subsequently, the northern arc collided with the North China Craton and post-orogenic extension occurred

  4. Polymerization on the rocks: beta-amino acids and arginine

    NASA Technical Reports Server (NTRS)

    Liu, R.; Orgel, L. E.; Bada, J. L. (Principal Investigator)

    1998-01-01

    We have studied the accumulation of long oligomers of beta-amino acids on the surface of minerals using the 'polymerization on the rocks' protocol. We find that long oligopeptides of beta-glutamic acid which cannot be formed in homogeneous aqueous solution are accumulated efficiently on the surface of hydroxylapatite using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDAC) as condensing agent. The EDAC-induced oligomerization of aspartic acid on hydroxylapatite proceeds even more efficiently. Hydroxylapatite can also facilitate the ligation of the tripeptide (glu)3. The 'polymerization on the rocks' scenario is not restricted to negatively-charged amino acids. Oligoarginines are accumulated on the surface of illite using carbonyldiimidizole (CDI) as condensing agent. We find that FeS2 catalyzes the CDI-induced oligomerization of arginine, although it does not adsorb oligoarginines. These results are relevant to the formation of polypeptides on the primitive earth.

  5. Polymerization on the rocks: beta-amino acids and arginine.

    PubMed

    Liu, R; Orgel, L E

    1998-06-01

    We have studied the accumulation of long oligomers of beta-amino acids on the surface of minerals using the 'polymerization on the rocks' protocol. We find that long oligopeptides of beta-glutamic acid which cannot be formed in homogeneous aqueous solution are accumulated efficiently on the surface of hydroxylapatite using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDAC) as condensing agent. The EDAC-induced oligomerization of aspartic acid on hydroxylapatite proceeds even more efficiently. Hydroxylapatite can also facilitate the ligation of the tripeptide (glu)3. The 'polymerization on the rocks' scenario is not restricted to negatively-charged amino acids. Oligoarginines are accumulated on the surface of illite using carbonyldiimidizole (CDI) as condensing agent. We find that FeS2 catalyzes the CDI-induced oligomerization of arginine, although it does not adsorb oligoarginines. These results are relevant to the formation of polypeptides on the primitive earth.

  6. Evolution of the Mazatzal province and the timing of the Mazatzal orogeny: Insights from U-Pb geochronology and geochemistry of igneous and metasedimentary rocks in southern New Mexico

    USGS Publications Warehouse

    Amato, J.M.; Boullion, A.O.; Serna, A.M.; Sanders, A.E.; Farmer, G.L.; Gehrels, G.E.; Wooden, J.L.

    2008-01-01

    New U-Pb zircon ages, geochemistry, and Nd isotopic data are presented from three localities in the Paleoproterozoic Mazatzal province of southern New Mexico, United States. These data help in understanding the source regions and tectonic setting of magmatism from 1680 to 1620 Ma, the timing of the Mazatzal orogeny, the nature of postorogenic maginatism, Proterozoic plate tectonics, and provide a link between Mazatzal subblocks in Arizona and northern New Mexico. The data indicate a period from 1680 to 1650 Ma in which juvenile felsic granitoids were formed, and a later event between 1646 and 1633 Ma, when these rocks were deformed together with sedimentary rocks. No evidence of pre-1680 Ma rocks or inherited zircons was observed. The igneous rocks have ENd(t) from -1.2 to +4.3 with most between +2 and +4, suggesting a mantle source or derivation from similar-aged crust. Nd isotope and trace element concentrations are consistent with models for typical are magmatism. Detrital zircon ages from metasedimentary rocks indicate that sedimentation occurred until at least 1646 Ma. Both local and Yavapai province sources contributed to the detritus. All of the samples older than ca. 1650 Ma are deformed, whereas undeformed porphyroblasts were found in the contact aureole of a previously dated 1633 Ma gabbro. Regionally, the Mlazatzal orogeny occurred mainly between 1654 and 1643 Ma, during final accretion of a series of island arcs and intervening basins that may have amalgamated offshore. Rhyolite magmatism in the southern Mazatzal province was coeval with gabbro intrusions at 1633 Ma and this bimodal magmatism may have been related to extensional processes following arc accretion. ?? 2007 Geological Society of America.

  7. Collecting Rocks.

    ERIC Educational Resources Information Center

    Barker, Rachel M.

    One of a series of general interest publications on science topics, the booklet provides those interested in rock collecting with a nontechnical introduction to the subject. Following a section examining the nature and formation of igneous, sedimentary, and metamorphic rocks, the booklet gives suggestions for starting a rock collection and using…

  8. Pb, Sr, and Nd isotopic compositions of a suite of Large Archean, igneous rocks, eastern Beartooth Mountains - Implications for crust-mantle evolution

    NASA Technical Reports Server (NTRS)

    Wooden, J. L.; Mueller, P. A.

    1988-01-01

    Compositionally diverse Late Archean rocks (2.74-2.79 Ga old) from the eastern Beartooth Mountains (Montana and Wyoming) were studied and shown to have the same initial Pb, Sr, and Nd isotopic ratios. Lead and Sr initial ratios are higher and Nd initial values lower than predicted for rocks derived from model mantle sources and strongly indicate the involvement of an older crustal reservoir in the genesis of these rocks. A model involving subduction of continental detritus and contamination of the overlying mantle is suggested.

  9. Three-dimensional distribution of igneous rocks near the Pebble porphyry Cu-Au-Mo deposit in southwestern Alaska: constraints from regional-scale aeromagnetic data

    USGS Publications Warehouse

    Anderson, Eric D.; Zhou, Wei; Li, Yaoguo; Hitzman, Murray W.; Monecke, Thomas; Lang, James R.; Kelley, Karen D.

    2014-01-01

    Aeromagnetic data helped us to understand the 3D distribution of plutonic rocks near the Pebble porphyry copper deposit in southwestern Alaska, USA. Magnetic susceptibility measurements showed that rocks in the Pebble district are more magnetic than rocks of comparable compositions in the Pike Creek–Stuyahok Hills volcano-plutonic complex. The reduced-to-pole transformation of the aeromagnetic data demonstrated that the older rocks in the Pebble district produce strong magnetic anomaly highs. The tilt derivative transformation highlighted northeast-trending lineaments attributed to Tertiary volcanic rocks. Multiscale edge detection delineated near-surface magnetic sources that are mostly outward dipping and coalesce at depth in the Pebble district. The total horizontal gradient of the 10-km upward-continued magnetic data showed an oval, deep magnetic contact along which porphyry deposits occur. Forward and inverse magnetic modeling showed that the magnetic rocks in the Pebble district extend to depths greater than 9 km. Magnetic inversion was constrained by a near-surface, 3D geologic model that is attributed with measured magnetic susceptibilities from various rock types in the region. The inversion results indicated that several near-surface magnetic sources with moderate susceptibilities converge with depth into magnetic bodies with higher susceptibilities. This deep magnetic source appeared to rise toward the surface in several areas. An isosurface value of 0.02 SI was used to depict the magnetic contact between outcropping granodiorite and nonmagnetic sedimentary host rocks. The contact was shown to be outward dipping. At depths around 5 km, nearly the entire model exceeded the isosurface value indicating the limits of nonmagnetic host material. The inversion results showed the presence of a relatively deep, northeast-trending magnetic low that parallels lineaments mapped by the tilt derivative. This deep low represents a strand of the Lake Clark fault.

  10. Pb, Sr, and Nd isotopic compositions of a suite of Late Archean, igneous rocks, eastern Beartooth Mountains: implications for crust-mantle evolution

    USGS Publications Warehouse

    Wooden, J.L.; Mueller, P.A.

    1988-01-01

    A series of compositionally diverse, Late Archean rocks (2.74-2.79 Ga old) from the eastern Beartooth Mountains, Montana and Wyoming, U.S.A., have the same initial Pb, Sr, and Nd isotopic ratios. Lead and Sr initial ratios are higher and Nd initial ratios lower than would be expected for rocks derived from model mantle sources and strongly indicate the involvement of an older crustal reservoir in the genesis of these rocks. Crustal contamination during emplacement can be ruled out for a variety of reasons. Instead a model involving subduction of continental detritus and contamination of the overlying mantle as is often proposed for modern subduction environments is preferred. This contaminated mantle would have all the isotopic characteristics of mantle enriched by internal mantle metasomatism but would require no long-term growth or changes in parent to daughter element ratios. This contaminated mantle would make a good source for some of the Cenozoic mafic volcanics of the Columbia River, Snake River Plain, and Yellowstone volcanic fields that are proposed to come from ancient, enriched lithospheric mantle. The isotopic characteristics of the 2.70 Ga old Stillwater Complex are a perfect match for the proposed contaminated mantle which provides an alternative to crustal contamination during emplacement. The Pb isotopic characteristics of the Late Archean rocks of the eastern Beartooth Mountains are similar to those of other Late Archean rocks of the Wyoming Province and suggest that Early Archean, upper crustal rocks were common in this terrane. The isotopic signatures of Late Archean rocks in the Wyoming Province are distinctive from those of other Archean cratons in North America which are dominated by a MORB-like, Archean mantle source (Superior Province) and/or a long-term depleted crustal source (Greenland). ?? 1988.

  11. Chemical analyses of igneous rocks published from 1884 to 1900, with a critical discussion of the character and use of analyses

    USGS Publications Warehouse

    Washington, H.S.

    1903-01-01

    In the first two or three decades of the last century, when the study of rocks as such was being differentiated from that of minerals and of rock terranes that is, when the science of petrogaphy was in its infancy little attention was paid to their chemical features. It is true that a number had been analyzed, but these were for the most part rocks that were of such a character as to lead the investigator of those early days to consider them as minerals, as was the case with the first described Ihcrzolite and wehrlite. In contradistinction to the individually well-defined minerals, rocks were regarded as merely aggregates of minerals, in presumably fortuitous combinations, and lacking that definiteness or constancy of composition in one mass or in different masses which would justify their chemical study as a whole. As, however, they became more and more the subjects of special research, beginning with the earliest investigations of Cordiera, a knowledge of their chemical composition assumed gradually increasing interest. The great importance of this side of the study of rocks was first clearly recognized by Abich, who pointed out, as early as 1841, the, necessity of a knowledge of their chemical composition for the solution of such problems as their origin, mode of formation, and connection with the interior of the earth, as well as the value of a comparison of their analyses as a proper basis for their classification and nomenclature. To him, therefore, is due the credit, of introducing the chemical composition of rocks as a basis for their classification; though the good influence of this suggestion for their right understanding was largely nullified by the coincident use of the feldspars alone as one of the main factors of classification, an idea which has had a deplorably retarding influence on the development of systematic petrography for many years, and which, even at the present day, holds many systematists firmly in its grasp.

  12. In-situ zircon U-Pb age and Hf-O isotopic constraints on the origin of the Hasan-Robat A-type granite from Sanandaj-Sirjan zone, Iran: implications for reworking of Cadomian arc igneous rocks

    NASA Astrophysics Data System (ADS)

    Honarmand, Maryam; Li, Xian-Hua; Nabatian, Ghasem; Neubauer, Franz

    2017-01-01

    The Lower Permian Hasan-Robat syenogranite occurs as a single pluton and intruded the Upper Carboniferous-Lower Permian sandstones and dolomitic limestones in the central part of the Sanandaj-Sirjan zone. This syenogranitic intrusion shows A-type granitic affinity and is a good representative of Early Permian igneous activity in Iran. SIMS U-Pb zircon analyses indicate a crystallization age of 294.2 ± 2.5 Ma for the Hasan-Robat A-type granite. In-situ Lu-Hf and oxygen isotope analyses of magmatic zircons were carried out to infer the magma sources and evolution of the Hasan-Robat A-type syenogranite. The Hf-O zircon isotopic compositions are relatively homogeneous, with nearly chondritic ɛHf(t) values of -0.8 to +2.4 corresponding to two-stage zircon Hf model ages of 1.15-1.36 Ga. The δ18O values of zircon range from +7.6 to +8.6‰. The Hf model ages of the Hasan-Robat zircons is within the range of those reported from the Cadomian granitoids in Iran. The isotopic features of the Hasan-Robat syenogranite are in good agreement with Hf isotopic values and Hf and Nd model ages reported from the Cadomian arc magmatic suites in Iran. Thus, partial melting of these Cadomian igneous rocks would be the favorite source for the Hasan-Robat syenogranitic magma during the opening of the Neotethys Ocean and separation of Iranian terranes from the northern margin of Gondwana.

  13. Lunar igneous intrusions.

    PubMed

    El-Baz, F

    1970-01-02

    Photographs taken from Apollo 10 and 11 reveal a number of probable igneous intrusions, including three probable dikes that crosscut the wall and floor of an unnamed 75-kilometer crater on the lunar farside. These intrusions are distinguished by their setting, textures, structures, and brightness relative to the surrounding materials. Recognition of these probable igneous intrusions in the lunar highlands slupports the indications of the heterogeneity of lunar materials and the plausibility of intrusive igneous activity, in addition to extrusive volcanism, on the moon.

  14. Origins of Igneous Layering

    NASA Astrophysics Data System (ADS)

    Marsh, Bruce

    Anyone who has ever seen a photo of a layered intrusion, let alone visited one first hand, or even seen a thin section from one, cannot help but be impressed by the stunning record of crystal growth and deposition. Such bodies stand as majestic monuments of undeniable evidence that intricate magmatic processes exist, processes that couple crystallization, convection, and crystal sorting to form rocks so highly ordered and beautiful that they are a wonder to behold. These are the altars to which petrologists must carry their conceived petrologic processes for approval.Although significant in number, the best layered intrusions seem to be found almost always in remote places. Their names, Bushveld, Muskox, Kiglapait, Stillwater, Duke Island, Skaergaard, Rhum, ring through igneous petrology almost as historic military battles (Saratoga, Antietam, Bull Run, Manassas, Gettysburg) do through American history. People who have worked on such bodies are almost folk heros: Wager, Deer, Brown, Jackson, Hess, Irvine, McBirney, Morse; these names are petrologic household words. Yet with all this fanfare and reverence, layered instrusions are nearly thought of as period pieces, extreme examples of what can happen, but not generally what does. This is now all changing with the increasing realization that these bodies are perhaps highly representative of all magmatic bodies. They are simply more dynamically complete, containing more of the full range of interactions, and of course, exposing a more complete record. They are one end of a spectrum containing lava flows, lava lakes, large sills, plutons, and layered intrusions. This book uniquely covers this range with an abundance of first-hand field observations and a good dose of process conceptualization, magma physics, and crystal growth kinetics.

  15. Determination of major elements by wavelength-dispersive X-ray fluorescence spectrometry and trace elements by inductively coupled plasma mass spectrometry in igneous rocks from the same fused sample (110 mg)

    NASA Astrophysics Data System (ADS)

    Amosova, Alena A.; Panteeva, Svetlana V.; Chubarov, Victor M.; Finkelshtein, Alexandr L.

    2016-08-01

    The fusion technique is proposed for simultaneous determination of 35 elements from the same sample. Only 110 mg of rock sample was used to obtain fused glasses for quantitative determination of 10 major elements by wavelength dispersive X-ray fluorescence analysis, 16 rare earth elements and some other trace elements by inductively coupled plasma mass spectrometry analysis. Fusion was performed with 1.1 g of lithium metaborate and LiBr solution as the releasing agent in platinum crucible in electric furnace at 1100 °C. The certified reference materials of ultramafic, mafic, intermediate and felsic igneous rocks have been applied to obtain the calibration curves for rock-forming oxides (Na2O, MgO, Al2O3, SiO2, P2O5, K2O, CaO, TiO2, MnO, Fe2O3) and some trace elements (Ba, Sr, Zr) determination by X-ray fluorescence analysis. The repeatability does not exceed the allowable standard deviation for a wide range of concentrations. In the most cases the relative standard deviation was less than 5%. Obtained glasses were utilized for the further determination of rare earth (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) and some other (Ba, Sr, Zr, Rb, Cs, Y, Nb, Hf, Ta, Th and U) trace elements by inductively coupled plasma mass spectrometry analysis with the same certified reference materials employed. The results could mostly be accepted as satisfactory. The proposed procedure essentially reduces the expenses in comparison with separate sample preparation for inductively coupled plasma mass spectrometry and X-ray fluorescence analysis.

  16. Strength and ductility of room-dry and water-saturated igneous rocks at low pressures and temperatures to partial melting. Final report

    SciTech Connect

    Friedman, M.; Handin, J.; Higgs, N.G.; Lantz, J.R.; Bauer, S.J.

    1980-11-01

    Rock types that are likely candidates for drilling were tested. Reported herein are the short-time ultimate strengths and ductilities determined at temperatures of 25/sup 0/ to 1050/sup 0/C and a strain rate of 10/sup -4/s/sup -1/ of (a) room-dry Mt. Hood Andesite, Cuerbio Basalt, and Charcoal (St. Cloud Gray) Granodiorite at confining pressures of 0, 50, and 100 MPa, (b) water-saturated specimens of the same three rocks at zero effective pressure (both pore and confining pressures of 50 MPa), and (c) room-dry Newberry Rhyolite Obsidian at 0 and 50 MPa. These strengths are then compared with the stresses developed at the wall of a borehole in an elastic medium at the appropriate temperatures and mean pressures to assess the problem of borehole stability. (MHR)

  17. Our World: The Rock Cycle

    NASA Video Gallery

    Find out how rocks brought to Earth by the Apollo astronauts have helped NASA learn more about the rock cycle. Compare igneous, sedimentary and metamorphic rocks found on Earth to three types of ro...

  18. Thermal infrared (2.5-13.5 μm) spectroscopic remote sensing of igneous rock types on particulate planetary surfaces

    USGS Publications Warehouse

    Salisbury, John W.; Walter, Louis S.

    1989-01-01

    Fundamental molecular vibration bands are significantly diminished by scattering. Thus such bands in spectra of fine particulate regoliths (i.e., dominated by <5-μm particles), or regoliths displaying a similar scale of porosity, are difficult to use for mineralogical or rock type identification. Consequently, other spectral features have been sought that may be more useful in spectroscopic remote sensing of composition. We find that mineralogical information is retained in overtones and combination tones of the fundamental molecular vibrations in the 3.0- to 7.0-μm region, but that relatively few minerals have a sufficiently distinctive band structure to be unambiguously identified with currently available techniques. More significantly, identification of general rock type, as defined by the SCFM chemical index (SCFM = SiO2/SiO2 + CaO + FeO + MgO), is possible using spectral features associated with the principal Christiansen frequency and with a region of relative transparency between the Si-O stretching and bending bands. However, environmental factors may affect the appearance and wavelengths of these features. Finally, prominent absorption bands may result from the presence of relatively small amounts of water, hydroxyl or carbonate, because absorption bands exhibited by these materials in the 2.7- to 4.0-μm region, where silicate spectra are otherwise featureless, increase strongly in spectral contrast with decreasing particle size. Such materials are thus detectable in very small amounts in a particulate regolith composed predominantly of silicate minerals.

  19. Predicting the Sources and Formation Mechanisms of Evolved Lunar Crust by Linking K/Ca Ratios of Lunar Granites to Analogous Terrestrial Igneous Rocks

    NASA Technical Reports Server (NTRS)

    Mills, R. D.; Simon, J. I.

    2012-01-01

    Although silicic rocks (i.e. granites and rhyolites) comprise a minor component of the sampled portion of the lunar crust, recent remote sensing studies [e.g., 1-4] indicate that several un-sampled regions of the Moon have significantly higher concentrations of silicic material (also high in [K], [U], and [Th]) than sampled regions. Within these areas are morphological features that are best explained by the existence of chemically evolved volcanic rocks. Observations of silicic domes [e.g., 1-5] suggest that sizable networks of silicic melt were present during crust formation. Isotopic data indicate that silicic melts were generated over a prolonged timespan from 4.3 to 3.9 Ga [e.g., 6-8]. The protracted age range and broad distribution of silicic rocks on the Moon indicate that their petrogenesis was an important mechanism for secondary crust formation. Understanding the origin and evolution of such silicic magmas is critical to determining the composition of the lunar crustal highlands and will help to distinguish between opposing ideas for the Moon's bulk composition and differentiation. The two main hypotheses for generating silicic melts on Earth are fractional crystallization or partial melting. On the Moon silicic melts are thought to have been generated during extreme fractional crystallization involving end-stage silicate liquid immiscibility (SLI) [e.g. 9, 10]. However, SLI cannot account for the production of significant volumes of silicic melt and its wide distribution, as reported by the remote global surveys [1, 2, 3]. In addition, experimental and natural products of SLI show that U and Th, which are abundant in the lunar granites and seen in the remote sensing data of the domes, are preferentially partitioned into the depolymerized ferrobasaltic magma and not the silicic portion [11, 12]. If SLI is not the mechanism that generated silicic magmas on the Moon then alternative processes such as fractional crystallization (only crystal

  20. Spatial-temporal framework for the closure of the Junggar Ocean in central Asia: New SIMS zircon U-Pb ages of the ophiolitic mélange and collisional igneous rocks in the Zhifang area, East Junggar

    NASA Astrophysics Data System (ADS)

    Xu, Xing-Wang; Jiang, Neng; Li, Xian-Hua; Wu, Chu; Qu, Xun; Zhou, Gang; Dong, Lian-Hui

    2015-11-01

    The closure time of the Junggar Ocean is one of the hottest topics surrounding the tectonic evolution of the Central Asian Orogenic Belt (CAOB). This paper reports SIMS zircon U-Pb ages of the ophiolitic mélange and collisional igneous rocks in the Zhifang area, East Junggar. Our new results reveal the following evidence: (1) the West Hill ophiolitic mélange in the Zhifang area contains segments of the 371 Ma MORB-type layered rocks and 363 Ma oceanic islands, which were intruded by the 348 Ma syn-collisional quartz diorites; (2) the ophiolitic mélange and 348 Ma syn-collisional quartz diorites are overlain by the 342 Ma andesitic tuffs; and (3) the 342 Ma andesitic tuffs and successive 332 Ma granodiorites-gabbro were formed at late-collisional setting, whereas the 314 Ma granitic porphyry at post-collisional setting. We suggest that the Junggar Ocean in the Zhifang area was opened before 371 Ma and 363 Ma, and possibly closed before 348 Ma. By combining the published U-Pb ages of the Mayile-Tangbale-Darbute-Kalamaili-Zhifang-Daheishan (MTDKZD) ophiolite belt, Early-Carboniferous volcanic rocks unconformably overlying the MTDKZD ophiolite belt, bimodal volcanic rocks and granitoids within and adjacent to the MTDKZD ophiolite belt, it is suggested that the Junggar Ocean was possibly opened scissors-like from the Neoproterozoic-Ordovician Mayile-Tangbale ocean eastwards through the Silurian-Devonian Darbute-Karamay ocean finally to the Devonian-Early-Carboniferous Kalamaili-Zhifang ocean, and closed scissors-like from the Zhifang-Kalamaili area in the eastern segment westwards to the Darbute-Karamay area in the western segment. Tectonic collage between the Yemaquan-Xiemisitai arc and Junggar block occurred at approximately 343-348 Ma. The Junggar orogenic belt went through late-collisional stage at 343-330 Ma, post-collisional period after 330 Ma, and post-collisional extensional regime after 320 Ma with an intensive stage at around 303 Ma.

  1. Two Distinct Sets of Magma Sources in Cretaceous Rocks From Magnet Cove, Prairie Creek, and Other Igneous Centers of the Arkansas Alkaline Province, USA

    NASA Astrophysics Data System (ADS)

    Duke, G. I.; Carlson, R. W.; Eby, G. N.

    2008-12-01

    Two distinct sets of magma sources from the Arkansas alkaline province (~106-89 Ma) are revealed by Sr-Nd-Pb isotopic compositions of olivine lamproites vs. other alkalic rock types, including carbonatite, ijolite, lamprophyres, tephrite, malignite, jacupirangite, phonolite, trachyte, and latite. Isotopic compositions of diamond-bearing olivine lamproites from Prairie Creek and Dare Mine Knob point to Proterozoic lithosphere as an important source, and previous Re-Os isotopic data indicate derivation from subcontinental mantle lithosphere. Both sources were probably involved in lamproite generation. Magnet Cove carbonatites and other alkalic magmas were likely derived from an asthenospheric source. Lamproite samples are isotopically quite different from other rock types in Sr-Nd-Pb isotopic space. Although three lamproite samples from Prairie Creek have a large range of SiO2 contents (40-60 wt %), initial values of ɛNd (-10 to -13), 206Pb/204Pb (16.61-16.81), 207Pb/204Pb (15.34-15.36), and 208Pb/204Pb (36.57-36.76) are low and similar. Only 87Sr/86Sr(i) displays a wide range in the Prairie Creek lamproites (0.70627-0.70829). A fourth lamproite from Dare Mine Knob has the most negative ɛNd(i) of -19. Lamproite isotope values show a significant crustal component and isotopically overlap subalkalic rhyolites from the Black Hills (SD), which assimilated Proterozoic crust. Six samples of carbonatite, ijolite, and jacupirangite from Magnet Cove and Potash Sulphur Springs exhibit the most depleted Sr-Nd isotopic signatures of all samples. For these rock types, 87Sr/86Sr(i) is 0.70352 - 0.70396, and ɛNd(i) is +3.8 - +4.3. Eight other rock types have a narrow range of ɛNd(i) (+1.9 - +3.7), but a wide range of 87Sr/86Sr(i) (0.70424 - 0.70629). These 14 samples comprise a fairly tight cluster of Pb isotopic values: 206Pb/204Pb (18.22-19.23), 207Pb/204Pb (15.54-15.62), and 208Pb/204Pb (38.38-38.94), suggesting very little crustal assimilation. They are most similar to EM-2

  2. Xenoliths of mafic/ultramafic igneous rocks as carriers of information on lower crust beneath Złotoryja - Jawor volcanic complex (SW Poland).

    NASA Astrophysics Data System (ADS)

    Dajek, Michał; Matusiak-Malek, Magdalena; Puziewicz, Jacek; Lipa, Danuta; Ntaflos, Theodors

    2016-04-01

    The Cenozoic alkaline volcanic rocks in Lower Silesia (SW Poland) are known for their mantle peridotite xenoliths. However, the mafic and ultramafic xenoliths with cumulative textures and of composition of olivine- or hornblende clinopyroxenite, clinopyroxenite, websterite, norite and gabbro occur in some of the lavas (6 sites) of the Złotoryja-Jawor volcanic complex. The xenoliths are anhydrous, only in Wilcza Góra minor amount of amphibole occurs. The Mg# of clinopyroxene varies from 0.54 (Ostrzyca Proboszczowicka clinopyroxenite) to 0.89 (Góra Świątek clinopyroxenite). Forsterite content in olivine varies from 64% (Winna Góra gabbro) to 86% (Wilcza Góra hornblende clinopyroxenite). Anortite content in plagioclase in nortite and gabbros is 33-56%. The Mg# in amphibole is 0.43 to 0.76. Clinopyroxene trace element composition is typically LREE enriched, but in Wilcza Góra norite and Mnisza Góra clinopyroxenite it is LREE-depleted. The calculated pressures of clinopyroxene crystallization (calculated by the algorithm of Nimis and Ulmer, 1998, CMP, 1998, 122-135, assuming all Fe to be 2+) is from 0.45 to 0.96 GPa pointing to crystallization of the pyroxenitic rocks in lower crust or at crust/mantle boundary. Theoretical melts in equilibrium with clinopyroxene enriched in LREE resemble the alkaline lavas from the area and we suggest they are cognate with host magmas. We explain variations in composition of mafic xenoliths from Wilcza Góra, Winna Góra and Grodziec to be a result of magma fractionation. Xenoliths containing clinopyroxene impoverished in LREE may represent lithologies inherited from Variscan oceanic crust. Megacrysts of clinopyroxene present in some of the localities cannot result from disintegration of mafic xenoliths This study was possible thanks to project NCN UMO-2014/15/B/ST10/00095 of Polish National Centre for Science.

  3. Reduction of acid rock drainage using steel slag in cover systems over sulfide rock waste piles.

    PubMed

    de Almeida, Rodrigo Pereira; Leite, Adilson do Lago; Borghetti Soares, Anderson

    2015-04-01

    The extraction of gold, coal, nickel, uranium, copper and other earth-moving activities almost always leads to environmental damage. In metal and coal extraction, exposure of sulfide minerals to the atmosphere leads to generation of acid rock drainage (ARD) and in underground mining to acid mine drainage (AMD) due to contamination of infiltrating groundwater. This study proposes to develop a reactive cover system that inhibits infiltration of oxygen and also releases alkalinity to increase the pH of generated ARD and attenuate metal contaminants at the same time. The reactive cover system is constructed using steel slag, a waste product generated from steel industries. This study shows that this type of cover system has the potential to reduce some of the adverse effects of sulfide mine waste disposal on land. Geochemical and geotechnical characterization tests were carried out. Different proportions of sulfide mine waste and steel slag were studied in leachate extraction tests. The best proportion was 33% of steel slag in dry weight. Other tests were conducted as follows: soil consolidation, saturated permeability and soil water characteristic curve. The cover system was numerically modeled through unsaturated flux analysis using Vadose/w. The solution proposed is an oxygen transport barrier that allows rain water percolation to treat the ARD in the waste rock pile. The results showed that the waste pile slope is an important factor and the cover system must have 5 m thickness to achieve an acceptable effectiveness.

  4. Ureilites are not igneous differentiates

    NASA Technical Reports Server (NTRS)

    Clayton, Robert N.; Mayeda, Toshiko K.

    1988-01-01

    Although most all meteorites are as old as the solar system (4.5 billion years), they can be subdivided into primitive and evolved groups, depending on the extent of their chemical and physical processing. Primitive meteorites, most of which are chondrites, are assemblages of dust and millimeter-sized pellets from the presolar nebula, which were not extensively heated and processed since their assembly. Thus they provide information about the conditions in the nebular cloud. Many of the evolved meteorites are achondrites, which are igneous rocks produced by melting on or within an asteroidal object known as the parent body. A major unsolved problem in solar system studies is identification of the source of heat which led to melting of the achondrites. The role of oxygen isotopes in establishing genetic relationships among meteorites is examined.

  5. Deformation Along the Southeast Extension of the Lake Mead Fault System Evaluated with Paleomagnetic Data From Miocene Igneous Rocks, Hoover Dam area, Nevada and Arizona

    NASA Astrophysics Data System (ADS)

    Geissman, J. W.

    2002-12-01

    At and near Hoover Dam, southeast of Las Vegas, Cenozoic left-slip offset along the NE-SW trending Lake Mead fault system (LMFS) has resulted in the apparent rotation of structures and total displacement of up to 65 km. Defining any rotation of blocks within and near the LMFS is critical to assessing the kinematics of strike-slip faulting and attending extension. Paleomagnetic data from Miocene volcanic and some sedimentary rocks and intrusions (over 160 sites) deposited on Precambrian basement show that part of the Hoover Dam locality has experienced counterclockwise rotation . The middle Miocene (ca. 14.2 Ma)Tuff of Hoover Dam (THD)(sampled at over 90 sites) yields a well-grouped characteristic magnetization (ChRM); about 5 km south and east of the dam, gently east-dipping, north-striking rocks of the THD yield a corrected ChRM of moderate positive inclination and northwest declination (D=324.8°, I=27.4°, a95=10.7°, k=24, N=9 sites). Structural corrections, based on compaction fabrics in the THD are consistent with stratigraphic contacts. The anomalous shallow inclination for the THD ChRM implies that it was emplaced over a short period of time during a field instability. contact and conglomerate test results are interpreted to show that the THD ChRM is primary. Corrected data from north and west of the dam (D=289.7°, I=30.2°,a95=8.6°,k=32, N=10) are interpreted to indicate about 35° of counterclockwise rotation (R= -35.1°, delR= 12.4, F= -2.8°, delF = 10.8, relative to data from south of the dam) of crust across the dam site, consistent with progressive changes in strike of tilted fault blocks. The transition from apparently unrotated crust to rotated crust occurs over a zone about 1 km wide, where blocks of THD and older strata have been tilted up to 50°, probably concurrent with rotation. Rotation of crust northwest of Hoover Dam may reflect differential extension northwest of the LMFS (e.g.,River Mountains area) as strain is partitioned into west to

  6. Bibliography for acid-rock drainage and selected acid-mine drainage issues related to acid-rock drainage from transportation activities

    USGS Publications Warehouse

    Bradley, Michael W.; Worland, Scott C.

    2015-01-01

    Acid-rock drainage occurs through the interaction of rainfall on pyrite-bearing formations. When pyrite (FeS2) is exposed to oxygen and water in mine workings or roadcuts, the mineral decomposes and sulfur may react to form sulfuric acid, which often results in environmental problems and potential damage to the transportation infrastructure. The accelerated oxidation of pyrite and other sulfidic minerals generates low pH water with potentially high concentrations of trace metals. Much attention has been given to contamination arising from acid mine drainage, but studies related to acid-rock drainage from road construction are relatively limited. The U.S. Geological Survey, in cooperation with the Tennessee Department of Transportation, is conducting an investigation to evaluate the occurrence and processes controlling acid-rock drainage and contaminant transport from roadcuts in Tennessee. The basic components of acid-rock drainage resulting from transportation activities are described and a bibliography, organized by relevant categories (remediation, geochemical, microbial, biological impact, and secondary mineralization) is presented.

  7. A numerical method for retrieving high oxygen isotope temperatures from plutonic igneous rocks: An example from the Laramie Anorthosite Complex, Wyoming, USA

    SciTech Connect

    Farquhar, J.; Chacko, T. . Dept. of Geology); Frost, B.R. )

    1992-01-01

    The Sybille Pit is a late-stage magnetite-ilmenite-plagioclase-bearing differentiate of the Laramie Anorthosite with a wide range of grain sizes and modal mineralogy. This variability makes Sybille an ideal locality in which to study the factors that affect isotopic thermometry in plutonic environments. The authors have developed a numerical model based on isotope exchange trajectories that retrieves close to magmatic temperatures for samples from Sybille. This method is based on the premise that hand sample-scale sub-systems close to exchange with each other at temperatures that exceed those of the constituent minerals. The temperature of hand-sample scale closure is retrieved by back calculating the isotope exchange trajectories to the temperature at which two samples with widely different model compositions are in isotopic equilibrium. Application of these methods to samples from Sybille provides promising results. Whereas conventional isotopic thermometry of individual samples yields a wide range of temperatures ([approximately]600 to > 1000 C) depending on the mineral-pair chosen, application of this numerical model to multiple samples yields temperatures of 1,070 [+-] 100 C which corresponds closely to the inferred solidus for these rocks.

  8. Igneous intrusions in coal-bearing sequences

    SciTech Connect

    Gurevich, A.B.; Shishlov, S.B.

    1987-08-01

    Intrusions of various compositions, sizes, and shapes have been observed in 115 out of 620 coal basins or deposits on all the continents. They are mainly subvolcanic and hypabyssal, with depths of emplacement estimated as ranging from a few hundred meters to 6 km, but usually 3-4 km. Compositionally, 42% are basic, 31% intermediate, 23% acid, and 4% ultrabasic. Mafic (and related) rock types include dolerites, trachydolerites, gabbro-dolerites, gabbro-monzonites, monzonites, diabases, gabbrodiabases, and less often gabbros and basalts (subvolcanic bodies). These mafic intrusions occur in coal formations of various ages from Carboniferous through Neogene, but predominate in Paleozoic (47%) and Cenozoic beds (45%). They also occur in coal formations of all genetic types, apart from those on ancient stable platforms, where there are no signs of intrusive activity. The mafic intrusions are almost everywhere associated with comagmatic lavas and tuffs (mainly in the younger strata), and the coal beds themselves are to some extent enriched in pyroclastic material, particularly in the upper horizons. This paper gives a worldwide review of igneous intrusions in coal beds. 24 references.

  9. Oxygen isotope exchange kinetics of mineral pairs in closed and open systems: Applications to problems of hydrothermal alteration of igneous rocks and Precambrian iron formations

    USGS Publications Warehouse

    Gregory, R.T.; Criss, R.E.; Taylor, H.P.

    1989-01-01

    The systematics of stable-isotope exchange between minerals and fluids are examined in the context of modal mineralogical variations and mass-balance considerations, both in closed and in open systems. On mineral-pair ??18O plots, samples from terranes that have exchanged with large amounts of fluid typically map out steep positively-sloped non-equilibrium arrays. Analytical models are derived to explain these effects; these models allow for different exchange rates between the various minerals and the external fluids, as well as different fluid fluxes. The steep arrays are adequately modelled by calculated isochron lines that involve the whole family of possible exchange trajectories. These isochrons have initially-steep near-vertical positive slopes that rotate toward a 45?? equilibrium slope as the exchange process proceeds to completion. The actual data-point array is thus analogous to the hand of an "isotopic clock" that measures the duration of the hydrothermal episode. The dimensionless ratio of the volumetric fluid flux to the kinetic rate parameter ( u k) determines the shape of each individual exchange trajectory. In a fluid-buffered system ( u k ??? 1), the solutions to the equations: (1) are independent of the mole fractions of the solid phases; (2) correspond to Taylor's open-system water/rock equation; and (3) yield straight-line isochrons that have slopes that approach 1 f, where f is the fraction reacted of the more sluggishly exchanging mineral. The isochrons for this simple exchange model are closely congruent with the isochrons calculated for all of the more complex models, thereby simplifying the application of theory to actual hydrothermal systems in nature. In all of the models an order of magnitude of time (in units of kt) separates steep non-equilibrium arrays (e.g., slope ??? 10) from arrays approaching an equilibrium slope of unity on a ??-?? diagram. Because we know the approximate lifetimes of many hydrothermal systems from geologic and

  10. Geochronology and geochemistry of early Paleozoic igneous rocks of the Lesser Xing'an Range, NE China: Implications for the tectonic evolution of the eastern Central Asian Orogenic Belt

    NASA Astrophysics Data System (ADS)

    Wang, Zhi-wei; Xu, Wen-liang; Pei, Fu-ping; Wang, Feng; Guo, Peng

    2016-09-01

    This paper presents new zircon U-Pb, Hf isotope, and whole-rock major and trace element data for early Paleozoic igneous rocks of the Lesser Xing'an Range, NE China, in order to constrain the early Paleozoic tectonic evolution of the eastern Central Asian Orogenic Belt (CAOB). Zircon U-Pb dating indicates that early Paleozoic magmatic events within the northern Songnen-Zhangguangcai Range Massif (SZM) can be subdivided into four stages: Middle Cambrian ( 505 Ma), Late Cambrian ( 490 Ma), Early-Middle Ordovician ( 470 Ma), and Late Ordovician (460-450 Ma). The Middle Cambrian monzogranites are K-rich, weakly to strongly peraluminous, and characterized by pronounced heavy rare earth element (HREE) depletions, high Sr/Y ratios, low Y concentrations, low primary zircon εHf(t) values (- 6.79 to - 1.09), and ancient two-stage model (TDM2) ages (1901-1534 Ma). These results indicate derivation from partial melting of thickened ancient crustal materials that formed during the amalgamation of the northern SZM and the northern Jiamusi Massif (JM). The Late Cambrian monzonite, quartz monzonite, and monzogranite units are chemically similar to A-type granites, and contain zircons with εHf(t) values of - 2.59 to + 1.78 and TDM2 ages of 1625-1348 Ma. We infer that these rocks formed from primary magmas generated by partial melting of Mesoproterozoic accreted lower crustal materials in a post-collisional extensional environment. The Early-Middle Ordovician quartz monzodiorite, quartz monzonite, monzogranite, and rhyolite units are calc-alkaline, relatively enriched in light REEs (LREEs) and large ion lithophile elements (LILEs; e.g., Rb, Th, and U), depleted in HREEs and high field strength elements (HFSEs; e.g., Nb, Ta, and Ti), and contain zircons with εHf(t) values of - 7.33 to + 4.98, indicative of formation in an active continental margin setting. The Late Ordovician alkali-feldspar granite and rhyolite units have A-type granite affinities that suggest they formed in an

  11. Effects of water-saturation on strength and ductility of three igneous rocks at effective pressures to 50 MPa and temperatures to partial melting

    SciTech Connect

    Bauer, S.J.; Friedman, M.; Handin, J.

    1981-01-01

    Instantaneous-failure strengths and ductilities of water-saturated cylindrical specimens of Charcoal Granodiorite, Mount Hood Andesite, and Cuerbio Basalt are determined at a strain rate of 10{sup -4}s{sup -1} and at effective confining pressures (Pe) of 0 and 50 MPa and at temperatures to partial melting. The data indicate: (1) at Pe = 0 and 50 MPa (Pc and Pp of 50 MPa and of 100 and 50 MPa, respectively) the granodiorite does not water-weaken; (2) at these same Pe the more porous and finer-grained andesite begins to exhibit water-weakening at about 600/sup 0/C; (3) at Pe = 0 and 870-900{sup 0}C the andesite's wet strength averages 20 MPa compared to 100 MPa, dry; (4) at Pe = 50 MPa and 920{sup 0}C its wet strength is 45 MPa compared to 160 MPa dry; (5) at Pe = 0, the basalt appears to be water-weakened above 800{sup 0}C; (6) water-saturated specimens deformed at temperatures less than T{sub m} exhibit ultimate strengths at less than 2 percent shortening and then work-soften along faults; and (7) both dry and wet specimens deform primarily by brittle fracture. Extrapolations indicate: (1) crystalline rocks should be drillable because they remain brittle until partial melting occurs, and penetration rates should increase with temperature because there is a corresponding decrease in brittle fracture strength; (2) boreholes in ''water-filled'' holes will be stable to >10 km at temperatures 10 km; and (4) open boreholes in the andesite are apt to be much less stable, and at similar temperatures would fail at 2 to 5-km depth.

  12. Was the Devonian geomagnetic field dipolar or multipolar? Palaeointensity studies of Devonian igneous rocks from the Minusa Basin (Siberia) and the Kola Peninsula dykes, Russia

    NASA Astrophysics Data System (ADS)

    Shcherbakova, V. V.; Biggin, A. J.; Veselovskiy, R. V.; Shatsillo, A. V.; Hawkins, L.; Shcherbakov, V. P.; Zhidkov, G. V.

    2017-02-01

    Defining variations in the behaviour of the geomagnetic field through geological time is critical to understanding the dynamics of Earth's core and its response to mantle convection and planetary evolution. Furthermore, the question of whether the axial dipole dominance of the recent palaeomagnetic field persists through the whole of Earth's history is fundamental to determining the reliability of palaeogeographic reconstructions and the efficacy of the magnetosphere in shielding Earth from solar wind radiation. Previous palaeomagnetic directional studies have suggested that the palaeofield had a complex configuration in the Devonian period (419-359 Ma). Here we present new palaeointensity determinations from rocks aged between 408 and 375 Ma from the Minusa Basin (southern Siberia), and the Kola Peninsula to investigate the strength of the field during this enigmatic period. Palaeointensity experiments were performed using the thermal Thellier, microwave Thellier, and Wilson methods on 165 specimens from 25 sites. Six out of eight successful sites from the Minusa Basin and all four successful sites from the Kola Peninsula produced extremely low palaeointensities (< 10 μT). These findings challenge the uniformitarian view of the palaeomagnetic field: field intensities of nearly an order of magnitude lower than Neogene values (except during relatively rare geomagnetic excursions and reversals) together with the widespread appearance of strange directions found in the Devonian suggest that the Earth's field during this time may have had a dominantly multipolar geometry. A persistent, low intensity multipolar magnetic field and associated diminished magnetosphere would increase the impact of solar particles on the Earth's magnetosphere, ionosphere and atmosphere with potential major implications for Earth's climate and biosphere.

  13. Igneous Rocks of the East Pacific Rise: The alkali volcanic suite appear to be differentiated from a tholeiitic basalt extruded from the mantle.

    PubMed

    Engel, A E; Engel, C G

    1964-10-23

    The apical parts of large volcanoes along the East Pacific Rise (islands and seamounts) are encrusted with rocks of the alkali volcanic suite (alkali basalt, andesine- and oligoclase-andesite, and trachyte). In contrast, the more submerged parts of the Rise are largely composed of a tholeiitic basalt which has low concentrations of K, P, U, Th, Pb, and Ti. This tholeiitic basalt is either the predominant or the only magma generated in the earth's mantle under oceanic ridges and rises. It is at least 1000-fold more abundant than the alkali suite, which is probably derived from tholeiitic basalt by magmatic differentiation in and immediately below the larger volcanoes. Distinction of oceanic tholeiites from almost all continental tholeiites is possible on the simple basis of total potassium content, with the discontinuity at 0.3 to 0.5 percent K(2)O by weight. Oceanic tholeiites also are readily distinguished from some 19 out of 20 basalts of oceanic islands and seamount cappings by having less than 0.3 percent K(2)O by weight and more than 48 percent SiO(2). Deep drilling into oceanic volcanoes should, however, core basalts transitional between the oceanic tholeiites and the presumed derivative alkali basalts. The composition of the oceanic tholeiites suggests that the mantle under the East Pacific Rise contains less than 0.10 percent potassium oxide by weight; 0.1 part per million of uranium and 0.4 part of thorium; a potassium:rubidium ratio of about 1200 and a potassium: uranium ratio of about 10(4).

  14. Did the Kiruna iron ores form as a result of a metasomatic or igneous process? New U-Pb and Nd data for the iron oxide apatite ores and their host rocks in the Norrbotten region of northern Sweden

    NASA Astrophysics Data System (ADS)

    Westhues, A.; Hanchar, J. M.; Whitehouse, M. J.; Fisher, C. M.

    2012-12-01

    -Pb dating of zircon from both host rock and ore samples confirms a previously documented event around 1880 - 1900 Ma in the Norrbotten region. However, U-Pb in monazite from an ore sample suggests a further event at ca. 1650 Ma, a period of known activity in Fennoscandia. Further investigation and more U-Pb data are needed to confirm those dates and how the iron mineralization is related to those two events. The combination of U-Th-Pb ages, tracer isotopes and trace element abundances at mineral scale (e.g., Lu-Hf in zircon, and Sm-Nd in monazite, apatite, titanite), along with the O isotopic composition of zircon, will be used to decipher whether the Kiruna iron ore deposits are of metasomatic or igneous origin. Overall, the study also intends to develop a predictive model for exploration of similar iron oxide apatite deposits worldwide.

  15. U-Pb Dating, whole rock and Sr-Nd-Pb-O isotope geochemistry of collisional magmatism in the CACC: Çiçekdaǧ igneous complex (ÇIC)

    NASA Astrophysics Data System (ADS)

    Deniz, Kiymet; Kagan Kadioglu, Yusuf; Stuart, Finlay; Ellam, Rob; Boyce, Adrian; Condon, Daniel

    2015-04-01

    The closure of Neotethys induced from calcalkaline through alkaline magmatism within the Central Anatolia Crystalline Complex (CACC) during the late Cretaceous-early Paleogene. Timing of these magmatism is very important for understanding the magmato-tectonic evolution and the relation with the collision. Despite the genesis of felsic products are well understood, there is lack of petrogenetic explanation about especially alkaline mafic products. The relation between Neotethyan ophiolites and late alkaline dykes which haven't reported before is the most important undeclared gap. Çiçekdağ igneous complex (ÇIC) is one of the best area for explaining all of these problems within the CACC. In accordance with these purposes, we have carried out detailed petrographic, whole rock geochemical, Sr-Nd-Pb-O isotopic and geochronological (U/Pb and Ar/Ar) study of the rocks in the ÇIC in order to unravel the magmatic history of the CACC and thus constrain the tectonic history. The intrusive rocks of the ÇIC are differentiated into four main group as an ophiolites, calcalkaline series, alkaline series and late alkaline dykes. The felsic and mafic units intruded to the ophiolitic rocks. The calcalkaline series mostly composed of monzonites and monzodiorite porphyry whereas the alkaline series consist of syenites and feldspathoid-bearing gabbros. Variations in the major oxide compositions of both rock series can be attributed with fractionation of clinopyroxene, plagioclase, amphibole, apatite and iron titan oxide minerals. The high 87Sr/86Sr and low 143Nd/144Nd of both series are indicative of mantle sources with large continental crustal components. Feldspar and quartz oxygen isotope data from calcalkaline and alkaline series have a range of δ18O values 5.1-11.4o 8.3-9.2o and 7.7-14.1o 10.2-13.7o respectively and are compatible with the values for I-A-type granitoids. Both rock series represent the mixed (mantle-crustal) origin. The combination of all data suggest that

  16. Rocks.

    ERIC Educational Resources Information Center

    Lee, Alice

    This science unit is designed for limited- and non-English speaking students in a Chinese bilingual education program. The unit covers rock material, classification, characteristics of types of rocks, and rock cycles. It is written in Chinese and simple English. At the end of the unit there is a list of main terms in both English and Chinese, and…

  17. Acid-rock drainage at Skytop, Centre County, Pennsylvania, 2004

    USGS Publications Warehouse

    Hammarstrom, Jane M.; Brady, Keith; Cravotta, Charles A.

    2005-01-01

    Recent construction for Interstate Highway 99 (I?99) exposed pyrite and associated Zn-Pb sulfide minerals beneath a >10-m thick gossan to oxidative weathering along a 40-60-m deep roadcut through a 270-m long section of the Ordovician Bald Eagle Formation at Skytop, near State College, Centre County, Pennsylvania. Nearby Zn-Pb deposits hosted in associated sandstone and limestone in Blair and Centre Counties were prospected in the past; however, these deposits generally were not viable as commercial mines. The pyritic sandstone from the roadcut was crushed and used locally as road base and fill for adjoining segments of I?99. Within months, acidic (pH1,000 mg/L), seep waters at the base of the cut contain >100 mg/L dissolved Zn and >1 mg/L As, Co, Cu, and Ni. Lead is relatively immobile (<10 ?g/L in seep waters). The salts sequester metals and acidity between rainfall events. Episodic salt dissolution then contributes pulses of contamination including acid to surface runoff and ground water. The Skytop experience highlights the need to understand dynamic interactions of mineralogy and hydrology in order to avoid potentially negative environmental impacts associated with excavation in sulfidic rocks.

  18. A Sustainable Approach for Acid Rock Drainage Treatment using Clinoptilolite

    NASA Astrophysics Data System (ADS)

    Li, L. Y.; Xu, W.; Grace, J. R.

    2009-04-01

    Problems related to acid rock drainage (ARD) occur along many highways of British Columbia. The ARD problem at Pennask Creek along Highway 97C in the Thompson-Okanagan region is an ideal site for pilot study to investigate a possible remediation solution. The highway was opened in 1991. An ARD problem was identified in 1997. Both sides of Highway 97C are producing acidified runoff from both cut rock surface and a fractured ditch. This runoff eventually enters Pennask Creek, the largest spawning source of rainbow trout in British Columbia. The current remediation technique using limestone for ARD treatment appears to be unnecessarily expensive, to generate additional solid waste and to not be optimally effective. A soil mineral natural zeolite - clinoptilolite - which is inexpensive and locally available, has a high metal adsorption capacity and a significant buffering capacity. Moreover, the clinoptilolite materials could be back-flushed and reused on site. An earlier batch adsorption study from our laboratory demonstrated that clinoptilolite has a high adsorption capacity for Cu, Zn, Al, with adsorption concentrations 131, 158 and 215 mg/kg clinoptilolite, respectively, from ARD of pH 3.3. Removal of metals from the loaded clinoptilolite by back-flushing was found to depend on the pH, with an optimum pH range for extraction of 2.5 to 4.0 for a contact time of one hour. The rank of desorption effectiveness was EDTA > NaCl > NaNO3 > NaOAC > NaHCO3 > Na2CO3 > NaOH > Ca(OH)2. A novel process involving cyclic adsorption on clinoptilolite followed by regeneration of the sorbent by desorption is examined for the removal of heavy metals from acid rock drainage. Experimental results show that the adsorption of zinc and copper depends on the pH and on external mass transfer. Desorption is assisted by adding NaCl to the water. A slurry bubble column was able to significantly reduce the time required for both adsorption and desorption in batch tests. XRD analysis indicated

  19. A Cultural Resources Site Inventory at Painted Rock Reservoir, Maricopa County, Arizona.

    DTIC Science & Technology

    1988-02-01

    basalt . The toolstone is actually a metamorphosed form of basalt more aptly termed metabasalt or greenstone. Greenstone is a generic term used . for...altered basic (as opposed to acid rocks such as granite or rhyolite) "’ igneous rocks, and includes felsites, basalts , and other rock types. To provide...continuity with the earlier work we have listed the black raw .. , materials as basalt and then qualified them to greenstone parenthetically. The

  20. Cosmogenic helium in a terrestrial igneous rock

    NASA Technical Reports Server (NTRS)

    Kurz, M. D.

    1986-01-01

    New helium isotopic measurements on samples from the Kula formation of Haleakala volcano of Hawaii are presented that are best explained by an in situ cosmogenic origin for a significant fraction of the He-3. Results from crushing and stepwise heating experiments, and consideration of the exposure age of the sample at the surface and the cosmic ray fluxes strongly support this hypothesis. Although crustal cosmogenic helium has been proposed previously, this represents its first unambiguous identification in a terrestrial sample.

  1. SNC meteorites - Igneous rocks from Mars

    NASA Technical Reports Server (NTRS)

    Wood, C. A.; Ashwal, L. D.

    1982-01-01

    It is argued that SNC (shergottite, nakhlite, chassignite) meteorites are ejecta from Mars. The mineralogy and chemistry of these objects is discussed, including rare earth element content, potassium/uranium ratios, oxidation state, oxygen isotopes, ages and isotopic evolution, magnetism, shock and texture. The possibility of SNC's deriving from Mercury, Venus, earth, moon, or a eucrite parent body is argued against. Mercury is too volatile-poor and anhydrous, Venus's atmosphere too thick and hot and its gravitational field too large, earth's oxygen isotope content too different from that of SNC's, the moon too different isotopically and chemically, and the ages of eucrites too different. Models suggest that SNC's could have escaped from Mars's gravitational field, and their composition supports Martian origin. Statistically, they could have reached the earth within their measured shock ages. Objections to the hypothesis are also discussed.

  2. Teaching the Rock Cycle with Ease.

    ERIC Educational Resources Information Center

    Bereki, Debra

    2000-01-01

    Describes a hands-on lesson for teaching high school students the concept of the rock cycle using sedimentary, metamorphic, and igneous rocks. Students use a rock cycle diagram to identify pairs of rocks. From the rock cycle, students explain on paper how their first rock became the second rock and vice versa. (PVD)

  3. Organic protomolecule assembly in igneous minerals.

    PubMed

    Freund, F; Staple, A; Scoville, J

    2001-02-27

    CH stretching bands, nu(CH), in the infrared spectrum of single crystals of nominally high purity, of laboratory-grown MgO, and of natural upper mantle olivine, provide an "organic" signature that closely resembles the symmetrical and asymmetrical C--H stretching modes of aliphatic -CH(2) units. The nu(CH) bands indicate that H(2)O and CO(2), dissolved in the matrix of these minerals, converted to form H(2) and chemically reduced C, which in turn formed C--H entities, probably through segregation into defects such as dislocations. Heating causes the C--H bonds to pyrolyze and the nu(CH) bands to disappear, but annealing at 70 degrees C causes them to reappear within a few days or weeks. Modeling dislocations in MgO suggests that the segregation of C can lead to C(x) chains, x = 4, with the terminal C atoms anchored to the MgO matrix by bonding to two O(-). Allowing H(2) to react with such C(x) chains leads to [O(2)C(CH(2))(2)CO(2)] or similar precipitates. It is suggested that such C(x)--H(y)--O(z) entities represent protomolecules from which derive the short-chain carboxylic and dicarboxylic and the medium-chain fatty acids that have been solvent-extracted from crushed MgO and olivine single crystals, respectively. Thus, it appears that the hard, dense matrix of igneous minerals represents a medium in which protomolecular units can be assembled. During weathering of rocks, the protomolecular units turn into complex organic molecules. These processes may have provided stereochemically constrained organics to the early Earth that were crucial to the emergence of life.

  4. Organic protomolecule assembly in igneous minerals

    PubMed Central

    Freund, Friedemann; Staple, Aaron; Scoville, John

    2001-01-01

    C—H stretching bands, νCH, in the infrared spectrum of single crystals of nominally high purity, of laboratory-grown MgO, and of natural upper mantle olivine, provide an “organic” signature that closely resembles the symmetrical and asymmetrical C—H stretching modes of aliphatic —CH2 units. The νCH bands indicate that H2O and CO2, dissolved in the matrix of these minerals, converted to form H2 and chemically reduced C, which in turn formed C—H entities, probably through segregation into defects such as dislocations. Heating causes the C—H bonds to pyrolyze and the νCH bands to disappear, but annealing at 70°C causes them to reappear within a few days or weeks. Modeling dislocations in MgO suggests that the segregation of C can lead to Cx chains, x = 4, with the terminal C atoms anchored to the MgO matrix by bonding to two O−. Allowing H2 to react with such Cx chains leads to [O2C(CH2)2CO2] or similar precipitates. It is suggested that such Cx—Hy—Oz entities represent protomolecules from which derive the short-chain carboxylic and dicarboxylic and the medium-chain fatty acids that have been solvent-extracted from crushed MgO and olivine single crystals, respectively. Thus, it appears that the hard, dense matrix of igneous minerals represents a medium in which protomolecular units can be assembled. During weathering of rocks, the protomolecular units turn into complex organic molecules. These processes may have provided stereochemically constrained organics to the early Earth that were crucial to the emergence of life. PMID:11226206

  5. Organic Protomolecule Assembly in Igneous Minerals

    NASA Technical Reports Server (NTRS)

    Freund, Friedemann; Staple, Aaron; Scoville, John

    2001-01-01

    C-H stretching bands in the infrared spectrum of single crystals of nominally high purity, laboratory-grown MgO and of natural upper mantle olivine provide an "organic" signature that closely resembles the symmetrical and asymmetrical C-H stretching modes of aliphatic -CH2- units. The C-H stretching bands indicate that H20 and CO2, dissolved in the matrix of these minerals, converted to form H2 and chemically reduced C, which in turn formed C-H entities, probably through segregation into defects such as dislocations. Heating causes the C-H bonds to pyrolyze and the C-H stretching bands to disappear, but annealing at 70 C causes them to reappear within a few days or weeks. Modeling dislocations in MgO suggests that the segregation of C can lead to Cx chains, x less than or equal to 4, with the terminal C atoms anchored to the MgO matrix by bonding to two U. Allowing H2 to react with such Cx chains leads to [O2C(CH2)2CO2] or similar precipitates. It is suggested that such Cx-Hy-Oz entities represent protomolecules from which derive the short-chain carboxylic and dicarboxylic and of the medium-chain fatty acids that have been solvent-extracted from crushed MgO and olivine single crystals, respectively. Thus it appears that the hard, dense matrix of igneous minerals represents a medium in which protomolecular units can be assembled. During weathering of rocks the protomolecular units turn into complex organic molecules. These processes may have provided stereochemically constrained organics to the early Earth that were crucial to the emergence of Life.

  6. Mixing-controlled uncertainty in long-term predictions of acid rock drainage from heterogeneous waste-rock piles

    NASA Astrophysics Data System (ADS)

    Pedretti, D.; Beckie, R. D.; Mayer, K. U.

    2015-12-01

    The chemistry of drainage from waste-rock piles at mine sites is difficult to predict because of a number of uncertainties including heterogeneous reactive mineral content, distribution of minerals, weathering rates and physical flow properties. In this presentation, we examine the effects of mixing on drainage chemistry over timescales of 100s of years. We use a 1-D streamtube conceptualization of flow in waste rocks and multicomponent reactive transport modeling. We simplify the reactive system to consist of acid-producing sulfide minerals and acid-neutralizing carbonate minerals and secondary sulfate and iron oxide minerals. We create multiple realizations of waste-rock piles with distinct distributions of reactive minerals along each flow path and examine the uncertainty of drainage geochemistry through time. The limited mixing of streamtubes that is characteristic of the vertical unsaturated flow in many waste-rock piles, allows individual flowpaths to sustain acid or neutral conditions to the base of the pile, where the streamtubes mix. Consequently, mixing and the acidity/alkalinity balance of the streamtube waters, and not the overall acid- and base-producing mineral contents, control the instantaneous discharge chemistry. Our results show that the limited mixing implied by preferential flow and the heterogeneous distribution of mineral contents lead to large uncertainty in drainage chemistry over short and medium time scales. However, over longer timescales when one of either the acid-producing or neutralizing primary phases is depleted, the drainage chemistry becomes less controlled by mixing and in turn less uncertain. A correct understanding of the temporal variability of uncertainty is key to make informed long-term decisions in mining settings regarding the management of waste material.

  7. Is phosphorus predictably incompatible in igneous processes?

    NASA Technical Reports Server (NTRS)

    Goodrich, C. A.; Barnes, S.

    1984-01-01

    Siderophile element abundances are central to recent models for core formation in the Earth and Moon and the origin of the Moon. It is important to identify siderophile elements whose behavior in igneous processes is predictable, so that primary mantle abundances can be deduced by subtracting out the effects of igneous processes. Newsom's model for core formation in the Moon requires subchondritic P, and suggests that P was depleted due to volatility. Experiments were conducted to determine P olivine/liquid distribution coefficients. Preliminary results indicate that P can be compatible with olivine during rapid cooling, but is not during isothermal crystallization with long growth times, and tends to be expelled during annealing. It is therefore not likely that P is compatible under any widespread igneous conditions, and the incompatible behavior of P in lunar crustal rocks can be safety assumed. In addition, low fO2 is insufficient to cause P compatibility, so it is unlikely that P-rich silicates formed during the early evolution of the Earth or Moon. These results indicate that P is depleted in the Moon.

  8. Volcanic rocks of the Mendeleev Ridge (Arctic Ocean) - evidences for existence of the large igneous provinces within Arctic region: on the data of the High Arctic Russian Expedition "Arctic-2012"

    NASA Astrophysics Data System (ADS)

    Sergeev, Sergey; Petrov, Oleg; Morozov, Andrey; Kremenetsky, Alexander; Gusev, Evgeny; Shevchenko, Sergey; Krymsky, Robert; Belyatsky, Boris; Antonov, Anton; Rodionov, Nikolay

    2013-04-01

    rocks and progressive magmas evolution during mixing of asthenospheric substances of the upwelling plume with the lithospheric component. Relatively high-radiogenic osmium isotope composition of the studied basalts (187Os/188Omeas=0.51525-1.07316) indicates the presence of significant share of the enriched lithospheric component in the source of basalt melts and the formation of this source at expense of relatively aged substances (model Re-Os ages from 600 to 1200 Ma). Age determination of the studied basalts effusions by argon-argon method is ongoing process but we have separated about 30 zircon grains mainly magmatic appearance (Th/U=0.6-2.0, long-prismatic grains without any visible signs of digestion and recrystallization, and overgrowths) from 4 samples and determined their U-Pb SHRIMP ages. Obtained age clusters indicate existence of old sialic basement underlying Mendeleev Ridge rocks (captured zircons with the ages of 2.7, 1.9, 1.6 and 0.8-1.2 Ga), which composition could be correlated with continental complexes of the Eurasia margins. At the same time, the finding of the volcanogenic zircons within the basalts with the ages of 127 and 260 Ma does not exclude the plausible existence on the studied territory of Polar Arctic of basalt effusions of two (or more) of igneous complexes corresponded with activities of mantle plumes - Cretaceous-Cenozoic (HALIP) and Triassic-Permian (resembling Siberian traps) ages

  9. Amino acids and hydrocarbons approximately 3,800-Myr old in the Isua rocks, southwestern Greenland

    NASA Technical Reports Server (NTRS)

    Nagy, B.; Engel, M. H.; Zumberge, J. E.; Ogino, H.; Chang, S. Y.

    1981-01-01

    Results of an analysis of amino acids and hydrocarbons found in the Isua banded iron formation, which contains the oldest known rocks on earth, are discussed. Similarities are pointed out between the relative amino acid abundances of the Isua rocks and those of lichens found on their surfaces, and a lack of substantial racemization indicated by the low D/L ratios in the 3800-million year old rock samples is noted. Experimental results showing the possibility of amino acid diffusion from lichens into the rocks are presented. Comparisons of the Isua rock amino acid D/L ratios with those reported for samples from other regions indicates that none of the Isua amino acids are older than a few tens of thousands to a few hundred thousand years. Analyses of the saturated hydrocarbons of the Isua samples reveals no odd carbon number preference, which may indicate antiquity, however laboratory experiments have shown that amino acids and aromatic and saturated aliphatic hydrocarbons could not have survived the metamorphic history of the Isua rocks. The evidence presented thus suggests that the amino acids and hydrocarbons found are not of the age of the sediments.

  10. Operational Lessons Learned During Bioreactor Demonstrations for Acid Rock Drainage Treatment

    EPA Science Inventory

    The U.S. Environmental Protection Agency’s Mine Waste Technology Program (MWTP) has emphasized the development of biologically-based treatment technologies for acid rock drainage (ARD). Progressively evolving technology demonstrations have resulted in significant advances in sul...

  11. Operational Lessons Leaned During bioreactor Demonstrations for Acid Rock Drainage Treatment

    EPA Science Inventory

    The U.S. Environmental Protection Agency's Mine Waste Technology Program (MWTP) has emphasized the development of biologically-based treatment technologies for acid rock drainage (ARD). Progressively evolving technology demonstrations have resulted in significant advances in sulf...

  12. Testing the Role of Silicic Acid and Bioorganic Materials in the Formation of Rock Coatings

    SciTech Connect

    Kolb, Vera; Philip, Ajish I.; Perry, Randall S.

    2004-12-01

    Silica, amino acids, and DNA were recently discovered in desert varnish. In this work we experimentally test the proposed role of silicic acid and bio-chemicals in the formation of desert varnish and other rock coatings. We have developed a protocol in which hte rocks were treated with a mixture of silicic acid, sugars, amino acids, metals and clays, under the influence of heat and UV light. This protocol reflects the proposed mechanism of hte polymerization of silicic acid with the bioorganic materials, and the laboratory model for the natural conditions under which the desert varnish is formed. Our experiments produced coatings with a hardness and morphology that resemble the nature ones. These results provide a support for the role of silicic acid in the formation of rock coatings. Since the hard silica-based coatings preserve organic compounds in them, they may serve as a biosignature for life, here or possibly Mars.

  13. 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.

  14. Progress report (1953) on the revision of Washington's Chemical analyses of igneous rocks (U.S.G.S. Prof. Paper 99), presented at the First International Symposium on Geochemistry, under the auspices of the International Union of Chemistry, in Zurich, August 11-13, 1953

    USGS Publications Warehouse

    Hooker, Marjorie

    1954-01-01

    In October of last year, vhen I was here in Zurich, it was my privilege to talk with Professor Niggli about the revision of Washington's "Chemical analysis of igneous rocks" which the United States Geological Survey is undertaking. It was then that he suggested the possibility of a progress report at this meeting in order that information about the revision would be available to those who are most interested. At the time that I talked with Professor Niggli the place or this meeting had not bean decided, but I think he hoped that it would be in Zurich,, Today, we must proceed without him, but I am sure that you must feel, as I do, that he is here sn spirit and that he expects us to continue the work as he would have, - with enthusiasm, with strength, and with happiness.

  15. Conceptual models of the formation of acid-rock drainage at road cuts in Tennessee

    USGS Publications Warehouse

    Bradley, Michael W.; Worland, Scott; Byl, Tom

    2015-01-01

    Pyrite and other minerals containing sulfur and trace metals occur in several rock formations throughout Middle and East Tennessee. Pyrite (FeS2) weathers in the presence of oxygen and water to form iron hydroxides and sulfuric acid. The weathering and interaction of the acid on the rocks and other minerals at road cuts can result in drainage with low pH (< 4) and high concentrations of trace metals. Acid-rock drainage can cause environmental problems and damage transportation infrastructure. The formation and remediation of acid-drainage from roads cuts has not been researched as thoroughly as acid-mine drainage. The U.S Geological Survey, in cooperation with the Tennessee Department of Transportation, is conducting an investigation to better understand the geologic, hydrologic, and biogeochemical factors that control acid formation at road cuts. Road cuts with the potential for acid-rock drainage were identifed and evaluated in Middle and East Tennessee. The pyrite-bearing formations evaluated were the Chattanooga Shale (Devonian black shale), the Fentress Formation (coal-bearing), and the Precambrian Anakeesta Formation and similar Precambrian rocks. Conceptual models of the formation and transport of acid-rock drainage (ARD) from road cuts were developed based on the results of a literature review, site reconnaissance, and the initial rock and water sampling. The formation of ARD requires a combination of hydrologic, geochemical, and microbial interactions which affect drainage from the site, acidity of the water, and trace metal concentrations. The basic modes of ARD formation from road cuts are; 1 - seeps and springs from pyrite-bearing formations and 2 - runoff over the face of a road cut in a pyrite-bearing formation. Depending on site conditions at road cuts, the basic modes of ARD formation can be altered and the additional modes of ARD formation are; 3 - runoff over and through piles of pyrite-bearing material, either from construction or breakdown

  16. Do the Columbia Hills of Gusev Crater Represent a Layered Igneous Intrusion on Mars?

    NASA Astrophysics Data System (ADS)

    Francis, D.

    2009-12-01

    The Martian Rover Spirit has now collected some 60 whole-rock chemical analyses on rock outcrops and boulders on its traverse from its landing site on the Gusev crater plains into the nearby Columbia Hills. Although Fe-rich “basaltic” compositions dominate the data set, there is a relatively wide range of mafic compositions that define a striking trend of increasing Fe with increasing Mg, and a small subset of ultramafic compositions at higher Mg. Although many of the analyzed samples have been shown to have experienced the effects of acidic chemical weathering, only the minor elements S, P, and K appear to have been seriously disturbed. Comparisons of analyses of rocks before and after abrasion suggests that it is unlikely that the co-variation between Fe and Mg in the Spirit whole rock analyses is a weathering effect. Despite the coherence of the array of Spirit data in Fe-Mg space, however, no plausible crystal fractionation model can explain the decrease in Fe with Mg within the mafic samples, nor relate the ultramafic samples to the mafic ones, if the samples of the data set are assumed to represent volcanic compositions defining a liquid line of descent. This reflects a fundamental inconsistency between the compositions of the olivine present (Fo~50-60), as estimated by Mössbauer analysis, and that predicted on the basis of Fe/Mg partitioning (Fo ~ 80). Positively correlated linear arrays in Fe - Mg space are, however, a common feature of whole rock data collected across cyclic feldspar-rich and mafic-rich cumulates in layered igneous intrusions. In such cyclically layered sequences, the whole rock compositions reflect magmatic crystal sorting, and scatter along mixing lines between the compositions of dominant cumulate phases. There is in fact a striking correspondence between the Fe-Mg array of Spirit data and those of dunite to troctolite cumulate layers in the Fe-rich Lac Raudot Troctolite Complex of the Grenville Province of Québec. If the Spirit

  17. Martian Igneous Geochemistry: The Nature of the Martian Mantle

    NASA Technical Reports Server (NTRS)

    Mittlefehldt, D. W.; Elkins-Tanton, L. T.; Peng, Z. X.; Herrin, J. S.

    2012-01-01

    Mafic igneous rocks probe the interiors of their parent objects, reflecting the compositions and mineralogies of their source regions, and the magmatic processes that engendered them. Incompatible trace element contents of mafic igneous rocks are widely used to constrain the petrologic evolution of planets. We focus on incompatible element ratios of martian meteorites to constrain the petrologic evolution of Mars in the context of magma ocean/cumulate overturn models [1]. Most martian meteorites contain some cumulus grains, but regardless, their incompatible element ratios are close to those of their parent magmas. Martian meteorites form two main petrologic/ age groupings; a 1.3 Ga group composed of clinopyroxenites (nakhlites) and dunites (chassignites), and a <1 Ga group composed of basalts and lherzolites (shergottites).

  18. Vertical structure of a caldera-filling pyroclastics and post-caldera granitic sill: the Middle Miocene Kumano Acidic Rocks emplaced in the Paleogene Shimanto accretionary complex, Japan

    NASA Astrophysics Data System (ADS)

    Nakajima, T.; Geshi, N.; Oikawa, T.; Shinjoe, H.; Miura, D.; Koizumi, N.

    2009-04-01

    migration of interstitial vapor-rich fluid during the cooling of the sill from its basement. Mineralogically and geochemically, the Kumano Granite Porphyry is nearly homogeneous. The size and contents of phenocryst is almost constant through the drilling core sample. A lot of metasedimentary xenoliths and mafic magmatic enclaves are included in the Kumano Granite Porphyry. The mafic enclave consists mainly of porphyritic tonalite and quartz diorites. Gabbro is rare. The metasedimentary xenolith consists of pelitic-psammitic gneisses and nearly unmetamorphosed mud- and siltstones. Xenocrysts of cordierite, andalusite and garnet are observed. The Kumano Acidic Rock and other Miocene acidic rocks in Southwest Japan are generated with a near-trench magmatism due to the subduction of a young hot Philippine Sea plate beneath the Southwest Japan arc. The S-type-like mineralogy and rather enriched isotopic character of the Kumano Acidic Rocks imply a magma source involving the component of the Shimanto accretionary complex. Displacement of the basement of volcanic tuff layer suggests a subsidence of caldera floor during the igneous activity. At the bottom of the drill hole, about 500 m below sea level, the basement of the tuff layer did not expose, whereas basement of the tuff layer distributes almost flat at the ground surface 2 - 3 km south of the well about 400 -500 m a.s.l.. This relationship indicates more than 1000 m of vertical displacement of the tuff layer between these two areas. This displacement could be explained by the existence of caldera wall between two areas, which associates the eruption of the welded tuff. No remarkable deformation is observed in the Kumano Granite Porphyry. The Kumano Granite Porphyry is a post-caldera intrusion possibly associated with the caldera resurgent activity.

  19. 7th international conference on acid rock drainage

    SciTech Connect

    Barnhisel, R.I.

    2006-07-01

    This meeting also serves as the 23rd annual meeting of the American Society of Mining and Reclamation. The papers discussed various aspects of acid mine drainage including its impact, sustainability issues, case studies, lessons learned, characterization, closure/land use issues, emerging technologies, forestry/ecology, abandoned mine lands, modelling, pit lakes/backfill, soils and overburden, and treatment.

  20. Magnetic properties, acid neutralization capacity, and net acid production of rocks in the Animas River Watershed Silverton, Colorado

    USGS Publications Warehouse

    McCafferty, Anne E.; Yager, Douglas B.; Horton, Radley M.; Diehl, Sharon F.

    2006-01-01

    Federal land managers along with local stakeholders in the Upper Animas River watershed near Silverton, Colorado are actively designing and implementing mine waste remediation projects to mitigate the effects of acid mine drainage from several abandoned hard rock metal mines and mills. Local source rocks with high acid neutralization capacity (ANC) within the watershed are of interest to land managers for use in these remediation projects. A suite of representative samples was collected from propylitic to weakly sericitic-altered volcanic and plutonic rocks exposed in outcrops throughout the watershed. Acid-base accounting laboratory methods coupled with mineralogic and geochemical characterization provide insight into lithologies that have a range of ANC and net acid production (NAP). Petrophysical lab determinations of magnetic susceptibility converted to estimates for percent magnetite show correlation with the environmental properties of ANC and NAP for many of the lithologies. A goal of our study is to interpret watershed-scale airborne magnetic data for regional mapping of rocks that have varying degrees of ANC and NAP. Results of our preliminary work are presented here.

  1. Ages of igneous and hydrothermal events in the Round Mountain and Manhattan gold districts, Nye County, Nevada.

    USGS Publications Warehouse

    Shawe, D.R.; Marvin, R.F.; Andriessen, P.A.M.; Mehnert, H.H.; Merritt, V.M.

    1986-01-01

    Isotopic age determinations of rocks and minerals separated from them are applied to refining and correlating the geological history of igneous and mineralizing events in a part of the Basin and Range province. -G.J.N.

  2. Acid-base properties of bentonite rocks with different origins.

    PubMed

    Nagy, Noémi M; Kónya, József

    2006-03-01

    Five bentonite samples (35-47% montmorillonite) from a Sarmatian sediment series with bentonite sites around Sajóbábony (Hungary) is studied. Some of these samples were tuffogenic bentonite (sedimentary), the others were bentonitized tuff with volcano sedimentary origin. The acid-base properties of the edge sites were studied by potentiometric titrations and surface complexation modeling. It was found that the number and the ratio of silanol and aluminol sites as well as the intrinsic stability constants are different for the sedimentary bentonite and bentonitized tuff. The characteristic properties of the edges sites depend on the origins. The acid-base properties are compared to other commercial and standard bentonites.

  3. COMPOST-FREE BIOREACTOR TREATMENT OF ACID ROCK DRAINAGE LEVIATHAN MINE, CALIFORNIA INNOVATIVE TECHNOLOGY EVALUATION REPORT

    EPA Science Inventory

    As part of the Superfund Innovative Technology Evaluation (SITE) program, an evaluation of the compost-free bioreactor treatment of acid rock drainage (ARD) from the Aspen Seep was conducted at the Leviathan Mine Superfund site located in a remote, high altitude area of Alpine Co...

  4. COMPOST-FREE BIOLOGICAL TREATMENT OF ACID ROCK DRAINAGE, TECHNICAL EVALUATION BULLETIN

    EPA Science Inventory

    As part of the Superfund Innovative Technology Evaluation (SITE) program, an evaluation of the compost-free bioreactor treatment of acid rock drainage (ARD) from the Aspen Seep was conducted at the Leviathan Mine Superfund site located in a remote, high altitude area of Alpine Co...

  5. COMPOST-FREE BIOREACTOR TREATMENT OF ACID ROCK DRAINAGE - TECHNOLOGY CAPSULE

    EPA Science Inventory

    As part of the Superfund Innovative Technology Evaluation (SITE) program, an evaluation of the compost-free bioreactor treatment of acid rock drainage (ARD) from the Aspen Seep was conducted at the Leviathan Mine Superfund site located in a remote, high altitude area of Alpine Co...

  6. PHYSICAL SOLUTIONS FOR ACID ROCK DRAINAGE AT REMOTE SITES DEMONSTRATION PROJECT

    EPA Science Inventory

    This report summarizes the results of Mine Waste Technology Program, Activity III, Project 42, Physical Solutions for Acid Rock Drainage at Remote Sites, funded by the U.S. Environmental Protection Agency (EPA) and jointly administered by EPA and the U.S. Department of Energy. A...

  7. Aqueous Alteration of Mars-Analog Rocks Under an Acidic Atmosphere

    NASA Technical Reports Server (NTRS)

    Bullock, M. A.; Moore, J. M.; Mellon, M. T.

    2001-01-01

    The wind-blown fines of Mars have high amounts of salts that are easily mobilized by water. We report on laboratory experiments that produce brines from the interaction of water with Mars-analog rocks and a simulated acidic Mars paleoatmosphere. Additional information is contained in the original extended abstract.

  8. Northeast Atlantic Igneous Province volcanic margin development

    NASA Astrophysics Data System (ADS)

    Mjelde, R.; Breivik, A. J.; Faleide, J. I.

    2009-04-01

    Early Eocene continental breakup in the NE Atlantic Volcanic Province (NAIP) was associated with voluminous extrusive and intrusive magmatism, and initial seafloor spreading produced anomalously thick oceanic crust. Recent publications based on crustal-scale wide-angle seismic data show that there is a positive correlation between igneous crustal thickness (H) and average P-wave velocity (Vp) on all investigated margins in the NAIP. Vp can be used as a proxy for crustal composition, which can be related to the mode of mantle melting. A positive H-Vp correlation indicates that excessive mantle melting the first few million years after breakup was driven by an initial increased temperature that cools off as seafloor spreading develops, consistent with a mantle plume model. Variations in mantle composition can explain excess magmatism, but will generate a negative H-Vp correlation. Active mantle convection may increase the flux of mantle rocks through the melting zone above the rate of passive corner flow, which can also produce excessive magmatism. This would produce little H-Vp correlation, and place the curve lower than the passive flow melting curve in the diagram. We have compiled earlier published results with our own analyses of published and unpublished data from different groups to look for systematic variations in the mantle melting mode along the NAIP margins. Earlier studies (Holbrook et al., 2002, White et al, 2008) on the southeast Greenland conjugate system, indicate that the thick igneous crust of the southern NAIP (SE Greenland ? Hatton Bank) was dominated by increased mantle temperature only, while magmatism closer to the southern side of and including the Greenland-Iceland-Færøy Ridge (GIFR) was created by combined temperature increase and active mantle convection. Recent publications (Breivik et al., 2008, White et al, 2008) north of the GIFR for the Norway Basin segment, indicate temperature dominated magmatism between the Jan Mayen Fracture

  9. 3D seismic interpretation of subsurface eruptive centers in a Permian large igneous province, Tazhong Uplift, central Tarim Basin, NW China

    NASA Astrophysics Data System (ADS)

    Yang, Jiangfeng; Zhu, Wenbin; Guan, Da; Zhu, Beibei; Yuan, Liansheng; Xiang, Xuemei; Su, Jinbao; He, Jingwen; Wu, Xinhui

    2016-11-01

    A 1445-km2 high-resolution 3D seismic reflection dataset is used to analyze the Permian large igneous province in the subsurface of the Tazhong area in the central Tarim Basin in northwestern China. Constrained by the synthetic seismograms of four wells, the top and base of the igneous rocks were identified in the seismic data. Seven large volcanic craters, each >10 km2 in area, have been discovered via the application of coherency and amplitude attributes. The thickness and volume of the igneous rocks were obtained by time-depth transformation. In the study area, all of the igneous rocks, with thicknesses from 120 to 1133 m, were formed by eruptions in the Early Permian. These events produced huge erupted volumes (178 km3) and multiple closely spaced volcanic edifices (<13 km). These features suggest that the study area may be the part of the eruptive center of the Permian igneous rocks in the Tarim Basin.

  10. 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.

  11. X-ray microtomography of hydrochloric acid propagation in carbonate rocks.

    PubMed

    Machado, A C; Oliveira, T J L; Cruz, F B; Lopes, R T; Lima, I

    2015-02-01

    Acid treatments are used in the oil and gas industry, to increase the permeability of the carbonate reservoirs by creating preferential channels, called wormholes. Channels formation is strongly influenced by acid type and injection rate. The aim of this study is to evaluate some characteristics of the microporous system of carbonate rocks, before and after acidizing. For that purpose X-ray high-resolution microtomography was used. The results show that this technique can be used as a reliable method to analyze microstructural characteristics of the wormholes.

  12. Phospholipid Analyses for Microbial Community Composition in Alpine Acid Rock Drainage

    NASA Astrophysics Data System (ADS)

    Webster, C. E.; Tapp, J. B.; Pfiffner, S. M.

    2008-12-01

    This project is examining factors of non-anthropogenic acid rock drainage that influence microbial community composition in the Peekaboo Gulch drainage basin (Sawatch Range, Colorado). At this site, natural acid rock drainage outflows from acidic springs (pH=2.6) on Red Mountain. The acid drainage converges with South Fork Lake Creek (pH ~ 7.0, prior to convergence) two miles down gradient. Sediment samples were collected across confluences with gradient of pH, temperature, conductivity and metal concentration. In-situ parameter measurements ranged from 2.3 to 7.9 of pH, 3.8 to 16.6 degree Celsius for temperature, and 34.9 to 1820 for conductivity. Biomass as measured by phospholipids ranged from 280 to 95,900 pmol/g sediment. The only relationship between the in situ parameters and the phospholipid profiles is a weak positive correlation between pH and branched monounsaturated fatty acid methyl esters in that at a pH greater than 5.0 these fatty acid methyl esters were detected. The phospholipid profiles were diverse across the samples. These profiles changed with respect to the spatial relationship within the drainage pattern. The highest alpine samples contained greater relative abundances of monounsaturated fatty acid methyl esters compared to the lower alpine samples. Microbial community profiles shifted at each confluence depending on water source chemistry. Continuing research is needed to determine other biogeochemical factors that may influence these community shifts.

  13. 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.

  14. Lead in the Getchell-Turquoise ridge Carlin-type gold deposits from the perspective of potential igneous and sedimentary rock sources in Northern Nevada: Implications for fluid and metal sources

    USGS Publications Warehouse

    Tosdal, R.M.; Cline, J.S.; Fanning, C.M.; Wooden, J.L.

    2003-01-01

    Lead isotope compositions of bulk mineral samples (fluorite, orpiment, and realgar) determined using conventional techniques and of ore-stage arsenian pyrite using the Sensitive High Resolution Ion-Microprobe (SHRIMP) in the Getchell and Turquoise Ridge Carlin-type gold deposits (Osgood Mountains) require contribution from two different Pb sources. One Pb source dominates the ore stage. It has a limited Pb isotope range characterized by 208Pb/206Pb values of 2.000 to 2.005 and 207Pb/206Pb values of 0.8031 to 0.8075, as recorded by 10-??m-diameter spot SHRIMP analyses of ore-stage arsenian pyrite. These values approximately correspond to 206Pb/204Pb of 19.3 to 19.6, 207Pb/204Pb of 15.65 to 15.75, and 208Pb/204Pb of 39.2 to 39.5. This Pb source is isotopically similar to that in average Neoproterozoic and Cambrian elastic rocks but not to any potential magmatic sources. Whether those clastic rocks provided Pb to the ore fluid cannot be unequivocally proven because their Pb isotope compositions over the same range as in ore-stage arsenian pyrite are similar to those of Ordovician to Devonian siliciclastic and calcareous rocks. The Pb source in the calcareous rocks most likely is largely detrital minerals, since that detritus was derived from the same sources as the detritus in the Neoproterozoic and Cambrian clastic rocks. The second Pb source is characterized by a large range of 206Pb/204Pb values (18-34) with a limited range of 208Pb/204Pb values (38.1-39.5), indicating low but variable Th/U and high and variable U/Pb values. The second Pb source dominates late and postore-stage minerals but is also found in preore sulfide minerals. These Pb isotope characteristics typify Ordovician to Devonian siliciclastic and calcareous rocks around the Carlin trend in northeast Nevada. Petrologically similar rocks host the Getchell and Turquoise Ridge deposits. Lead from the second source was either contributed from the host sedimentary rock sequences or brought into the

  15. Possible Biosphere-Lithosphere Interactions Preserved in Igneous Zircon and Implications for Hadean Earth.

    PubMed

    Trail, Dustin; Tailby, Nicholas D; Sochko, Maggie; Ackerson, Michael R

    2015-07-01

    Granitoids are silicic rocks that make up the majority of the continental crust, but different models arise for the origins of these rocks. One classification scheme defines different granitoid types on the basis of materials involved in the melting/crystallization process. In this end-member case, granitoids may be derived from melting of a preexisting igneous rock, while other granitoids, by contrast, are formed or influenced by melting of buried sedimentary material. In the latter case, assimilated sedimentary material altered by chemical processes occurring at the near surface of Earth-including biological activity-could influence magma chemical properties. Here, we apply a redox-sensitive calibration based on the incorporation of Ce into zircon crystals found in these two rock types, termed sedimentary-type (S-type) and igneous-type (I-type) granitoids. The ∼400 Ma Lachlan Fold Belt rocks of southeastern Australia were chosen for investigation here; these rocks have been a key target used to describe and explore granitoid genesis for close to 50 years. We observe that zircons found in S-type granitoids formed under more reducing conditions than those formed from I-type granitoids from the same terrain. This observation, while reflecting 9 granitoids and 289 analyses of zircons from a region where over 400 different plutons have been identified, is consistent with the incorporation of (reduced) organic matter in the former and highlights one possible manner in which life may modify the composition of igneous minerals. The chemical properties of rocks or igneous minerals may extend the search for ancient biological activity to the earliest period of known igneous activity, which dates back to ∼4.4 billion years ago. If organic matter was incorporated into Hadean sediments that were buried and melted, then these biological remnants could imprint a chemical signature within the subsequent melt and the resulting crystal assemblage, including zircon.

  16. The Search for Igneous Materials at the Viking Landing Sites

    NASA Technical Reports Server (NTRS)

    Arvidson, R. E.; Dale-Bannister, M.; Guinnes, E. A.

    1985-01-01

    The use of Viking Lander 6 channel (0.4 to 1.1 microns) images to identify igneous materials is discussed. Movies of synthetic image cubes demonstrate that there are a number of contrast reversals between soils and certain rocks. Typically, large, angular rocks are brighter than the surrounding soils in the shortest wavelengths, and much darker than the soils at longest wavelengths. These results, which seem difficult to explain solely on the basis of photometric effects related to local lighting and viewing, are consistent with the presence of Fe+2 bearing silicates at the rock surfaces, producing relatively moderate absorptions in the blue and green parts of the spectrum, but more significant absorptions near about 1.0 micrometer (e.g., Fe+2 bearing pyroxenes). The soils, on the other hand, have signatures consistent with strong Fe+3 related absorptions at shorter wavelengths (e.g., Fe+3 bearing oxides or hydroxides).

  17. East Candor Rocks

    NASA Technical Reports Server (NTRS)

    2004-01-01

    24 September 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a thick, massive outcrop of light-toned rock exposed within eastern Candor Chasma, part of the vast Valles Marineris trough system. Dark, windblown sand has banked against the lower outcrop slopes. Outcrops such as this in the Valles Marineris chasms have been known since Mariner 9 images were obtained in 1972. However, the debate as to whether these represent sedimentary or igneous rocks has not been settled within the Mars science community. In either case, they have the physical properties of sedimentary rock (that is, they are formed of fine-grained materials), but some igneous rocks made up of volcanic ash may also exhibit these properties. This image is located near 7.8oS, 65.3oW, and covers an area approximately 3 km (1.9 mi) across. The scene is illuminated by sunlight from the lower left.

  18. Alpine-type sensu strictu(ophiolitic) peridotites: Refractory residues from partial melting or igneous sediments? A contribution to the discussion of the paper: "The origin of ultramafic and ultrabasic rocks" by P.J. Wyllie

    USGS Publications Warehouse

    Thayer, T.P.

    1969-01-01

    Although Alpine peridotites and basaltic lavas are widely associated in eugeosynclines and oceanic areas, their genetic ties are obscure. Three major characteristics of olivine-rich Alpine peridotite and dunite-relict cumulus textures, aggregated masses of chromitite, and intimate association with magnesium-rich gabbro - cannot be explained by partial melting of garnet peridotite to form tholeiite. Association of magnesium-rich gabbro with the chromite-bearing and so-called high-temperature Alpine peridotites is believed to present problems that have not been considered by advocates of the partial-melting hypothesis. The chromite-bearing Alpine peridotites and related feldspathic rocks are believed to have formed near the top of the mantle by gravitational differentiation processes which are largely independent of the melting processes that produce basaltic magma at depths of 50 km or more. ?? 1969.

  19. The Paleozoic tectonic evolution and metallogenesis of the northern margin of East Junggar, Central Asia Orogenic Belt: Geochronological and geochemical constraints from igneous rocks of the Qiaoxiahala Fe-Cu deposit

    NASA Astrophysics Data System (ADS)

    Liang, Pei; Chen, Huayong; Hollings, Pete; Xiao, Bing; Wu, Chao; Bao, Zhiwei; Cai, Keda

    2016-11-01

    The East Junggar terrane (NW China) is an important constituent of the Central Asian Orogenic Belt (CAOB). From the Devonian to Permian, regional magmatism evolved from mainly calc-alkaline (I-type) to alkaline (A-type). The Qiaoxiahala Fe-Cu deposit, located in the Late Paleozoic Dulate island arc (northern margin of the East Junggar), is hosted in the volcanic rocks of the Middle Devonian Beitashan Formation. Two magmatic stages were identified in the deposit, the Qiaoxiahala diorite porphyry (380 ± 4.0 Ma) and a younger aplite (331 ± 3.1 Ma). The (high-K) calc-alkaline Beitashan Formation basaltic rocks are characterized by LILE and LREE enrichments and HFSE depletions, pointing to a subduction-related affinity. The high Mg# (42-75), elevated Ce/Th and Ba/Th, depleted Nb, positive εNd(t) (6.6), low (87Sr/86Sr)i (0.7037) and MORB-like Pb isotope characters all suggest an origin involving partial melting of a MORB-like depleted mantle wedge (metasomatized by slab-derived fluids) with little evidence of crustal contamination. The calc-alkaline (I-type) diorite porphyry, characterized by LILE and LREE enrichments and HFSE depletions, may have formed from fractional crystallization of the basaltic rocks, with its parental magma derived from the same depleted mantle wedge. The negative εHf(t) (-8.26), Hf model age (TDMC) of 1406 Ma and the presence of inherited zircons (ca. 470 and 506 Ma) indicate that the diorite has assimilated older crustal material. The alkaline, metaluminous (A-type) aplite is characterized by HFSE enrichment and depletions in Sr, P and Ti, distinct from the basaltic rocks and diorite porphyry at Qiaoxiahala. The low Mg# (35-38), positive Zr and Hf, positive εHf(t) (4.77-9.75) and εNd(t) (6.85-6.86) and low T2DM (538-520 Ma) suggest a juvenile lower crustal source due to partial melting of basaltic lower crust as a result of underplating of mantle-derived melts and accompanied by magma mixing. The tectonic evolution of the Paleozoic East

  20. Igneous history of the aubrite parent asteroid - evidence from the Norton County enstatite achondrite

    SciTech Connect

    Okada, A.; Keil, K.; Taylor, G.J.; Newsom, H.

    1988-03-01

    Numerous specimens of the Norton County enstatite achondrite (aubrite) were studied by optical microscopy, electron microprobe, and neutron-activation analysis. Norton County is found to be a fragmental impact breccia, consisting of a clastic matrix made mostly of crushed enstatite, into which are embedded a variety of mineral and lithic clasts of both igneous and impact melt origin. The Norton County precursor materials were igneous rocks, mostly plutonic orthopyroxenites, not grains formed by condensation from the solar nebula. The Mg-silicate-rich aubrite parent body experienced extensive melting and igneous differentiation, causing formation of diverse lithologies including dunites, plutonic orthopyroxenites, plutonic pyroxenites, and plagioclase-silica rocks. The presence of impact melt breccias (the microporphyritic clasts and the diopside-plagioclase-silica clast) of still different compositions further attests to the lithologic diversity of the aubrite parent body. 60 references.

  1. Igneous history of the aubrite parent asteroid - Evidence from the Norton County enstatite achondrite

    NASA Technical Reports Server (NTRS)

    Okada, Akihiko; Keil, Klaus; Taylor, G. Jeffrey; Newsom, Horton

    1988-01-01

    Numerous specimens of the Norton County enstatite achondrite (aubrite) were studied by optical microscopy, electron microprobe, and neutron-activation analysis. Norton County is found to be a fragmental impact breccia, consisting of a clastic matrix made mostly of crushed enstatite, into which are embedded a variety of mineral and lithic clasts of both igneous and impact melt origin. The Norton County precursor materials were igneous rocks, mostly plutonic orthopyroxenites, not grains formed by condensation from the solar nebula. The Mg-silicate-rich aubrite parent body experienced extensive melting and igneous differentiation, causing formation of diverse lithologies including dunites, plutonic orthopyroxenites, plutonic pyroxenites, and plagioclase-silica rocks. The presence of impact melt breccias (the microporphyritic clasts and the diopside-plagioclase-silica clast) of still different compositions further attests to the lithologic diversity of the aubrite parent body.

  2. Recrystallized Impact Glasses of the Onaping Formation and the Sudbury Igneous Complex, Sudbury Structure, Ontario, Canada

    NASA Technical Reports Server (NTRS)

    Dressler, B. O.; Weiser, T.; Brockmeyer, P.

    1996-01-01

    The origin of the Sudbury Structure and of the associated heterolithic breccias of the Onaping Formation and the Sudbury Igneous Complex have been controversial. While an impact origin of the structure has gained wide acceptance over the last 15 years, the origin of the recrystallized Onaping Formation glasses and of the igneous complex is still being debated. Recently the interpretation of the breccias of the Onaping Formation as suevitic fall-back impact breccias has been challenged. The igneous complex is interpreted either as a differentiated impact melt sheet or as a combination of an upper impact melt represented by the granophyre, and a lower, impact-triggered magmatic body consisting of the norite-sublayer formations. The Onaping Formation contains glasses as fluidal and nonfluidal fragments of various shapes and sizes. They are recrystallized, and our research indicates that they are petrographically heterogeneous and span a wide range of chemical compositions. These characteristics are not known from glasses of volcanic deposits. This suggests an origin by shock vitrification, an interpretation consistent with their association with numerous and varied country rock clasts that exhibit microscopic shock metamorphic features. The recrystallized glass fragments represent individual solid-state and liquid-state vitrified rocks or relatively small melt pods. The basal member lies beneath the Gray and Black members of the Onaping Formation and, where not metamorphic, has an igneous matrix. Igneous-textured melt bodies occur in the upper two members and above the Basal Member. A comparison of the chemical compositions of recrystallized glasses and of the matrices of the Basal Member and the melt bodies with the components and the bulk composition of the igneous complex is inconclusive as to the origin of the igneous complex. Basal Member matrix and Melt Bodies, on average, are chemically similar to the granophyre of the Sudbury Igneous Complex, suggesting that

  3. The Effects of Acid Rock Drainage (ARD) on Fluorescent Dissolved Organic Matter (DOM)

    NASA Astrophysics Data System (ADS)

    Lee, R. H.; Gabor, R. S.; SanClements, M.; McKnight, D. M.

    2011-12-01

    Located in the Rocky Mountains of central Colorado, the catchments drained by the headwaters of the Snake River are dominated by metal- and sulfide-rich bedrock. The breakdown of these minerals results in acidic metal-rich waters in the Snake (pH ~3) that persist until the confluence with Deer Creek (pH ~7). Previous research has been conducted examining the interactions of acid-rock drainage (ARD) and dissolved organic matter (DOM), but the effects of ARD on DOM production is not as well understood. In a synoptic study, samples of creek water were collected at evenly spaced intervals along the length of a tributary to the Snake River which drains an area with ARD. At each sampling location, water samples were collected and pH, conductivity, and temperature were measured. Water samples were analyzed for metal chemistry, and the DOM was analyzed with UV-Vis and fluorescence spectroscopy. The character of the DOM was described using PARAFAC and index calculations. This work demonstrates that the introduction of acid and dissolved metal species has notable effects on DOM composition. Preliminary data suggests that the introduction of acid drainage is responsible for the formation of a fluorophore not accounted for in the Cory and McKnight PARAFAC model. Both high concentrations of heavy metals (e.g. zinc) and the novel fluorophore are present downstream from a mining site, which indicates it as a possible source of both species. The data suggest a link between the introduction of fluorophores in acidic waters and acidophile populations at the source of the acid rock drainage.

  4. Teaching Igneous Geology in Physical Geography: Some Recommendations.

    ERIC Educational Resources Information Center

    Powell, William E.

    1982-01-01

    The most common igneous minerals and their diagnostic properties, which the author considers the most significant and pragmatic aspect of igneous geology for physical geography students, are discussed. The nature of igneous geology is also examined. (RM)

  5. On some fundamentals of igneous petrology

    NASA Astrophysics Data System (ADS)

    Marsh, Bruce D.

    2013-09-01

    The age-old process of crystal fractionation leading to the diversity of the igneous rocks and Earth itself is an exceedingly well-understood chemical process in magmatism and physical chemistry. But the broader physical aspects of this and related processes have proven elusive on many fronts, especially in its relation to the spatial variations in rock composition, texture, and macroscopic features like layering. Magmatic systems, be they volcanic, dikes, sills, or plutons, are generally analyzed with a problem at hand and an end result in mind. The processes invoked to solve these problems, which are most often purely chemical, are often unique to each problem with few if any general principles emerging that are central to understanding the wider perspective of magmatic processes and problems. An attempt is made at the outset to provide a list of inviolate Magmatic First Principles that are relevant to analyzing most magmatic problems. These involve: initial conditions; critical crystallinity; solidification fronts; transport and emplacement fluxes; phenocrysts, xenocrysts, primocrysts; crystal size; layering and crystal sorting; thermal convection; magmatic processes are physical. Along with these principles, two reference magmatic systems are suggested where the initial conditions and outcome are unequivocal: the Sudbury impact melt sheet and the Hawaiian lava lakes. Sudbury formed in ~5 min by superheated magma crystallized to a near uniform sequence, while the tiny lava lakes, formed of crystal-laden slurries, form a highly differentiated layered sequence. The major difference is in the initial conditions of formation, especially the nature of the input materials. The challenge is to construct and analyze magmatic systems (i.e., magma chambers, sills, dikes, and lavas) using these reference end members and the suggested principles. The Hawaiian 500,000 year volcanic record exhibits what can be expected as input materials, namely a highly varied output of

  6. Applicability Comparison of Methods for Acid Generation Assessment of Rock Samples

    NASA Astrophysics Data System (ADS)

    Oh, Chamteut; Ji, Sangwoo; Yim, Giljae; Cheong, Youngwook

    2014-05-01

    Minerals including various forms of sulfur could generate AMD (Acid Mine Drainage) or ARD (Acid Rock Drainage), which can have serious effects on the ecosystem and even on human when exposed to air and/or water. To minimize the hazards by acid drainage, it is necessary to assess in advance the acid generation possibility of rocks and estimate the amount of acid generation. Because of its relatively simple and effective experiment procedure, the method of combining the results of ABA (Acid Base Accounting) and NAG (Net Acid Generation) tests have been commonly used in determining acid drainage conditions. The simplicity and effectiveness of the above method however, are derived from massive assumptions of simplified chemical reactions and this often leads to results of classifying the samples as UC (Uncertain) which would then require additional experimental or field data to reclassify them properly. This paper therefore, attempts to find the reasons that cause samples to be classified as UC and suggest new series of experiments where samples can be reclassified appropriately. Study precedents on evaluating potential acid generation and neutralization capacity were reviewed and as a result three individual experiments were selected in the light of applicability and compatibility of minimizing unnecessary influence among other experiments. The proposed experiments include sulfur speciation, ABCC (Acid Buffering Characteristic Curve), and Modified NAG which are all improved versions of existing experiments of Total S, ANC (Acid Neutralizing Capacity), and NAG respectively. To assure the applicability of the experiments, 36 samples from 19 sites with diverse geologies, field properties, and weathering conditions were collected. The samples were then subject to existing experiments and as a result, 14 samples which either were classified as UC or could be used as a comparison group had been selected. Afterwards, the selected samples were used to conduct the suggested

  7. Impacts on water quality and biota from natural acid rock drainage in Colorado's Lake Creek watershed

    USGS Publications Warehouse

    Bird, D.A.; Sares, Matthew A.; Policky, Greg A.; Schmidt, Travis S.; Church, Stanley E.

    2006-01-01

    Colorado's Lake Creek watershed hosts natural acid rock drainage that significantly impacts surface water, streambed sediment, and aquatic life. The source of the ARD is a group of iron-rich springs that emerge from intensely hydrothermally altered, unexploited, low-grade porphyry copper mineralization in the Grizzly Peak Caldera. Source water chemistry includes pH of 2.5 and dissolved metal concentrations of up to 277 mg/L aluminum, 498 mg/L iron, and 10 mg/L copper. From the hydrothermally altered area downstream for 27 kilometers to Twin Lakes Reservoir, metal concentrations in streambed sediment are elevated and the watershed experiences locally severe adverse impacts to aquatic life due to the acidic, metal-laden water. The water and sediment quality of Twin Lakes Reservoir is sufficiently improved that the reservoir supports a trout fishery, and remnants of upstream ARD are negligible.

  8. Chemical stability of acid rock drainage treatment sludge and implications for sludge management

    SciTech Connect

    Danny M. McDonald; John A. Webb; Jeff Taylor

    2006-03-15

    To assess the chemical stability of sludges generated by neutralizing acid rock drainage (ARD) with alkaline reagents, synthetic ARD was treated with hydrated lime (batch and high-density sludge process), limestone, and two proprietary reagents (KB-1 and Bauxsol). The amorphous metal hydroxide sludge produced was leached using deionized water, U.S. EPA methods (toxicity characteristic leaching procedure, synthetic precipitation leaching procedure), and the new strong acid leach test (SALT), which leaches the sludge with a series of sulfuric acid extractant solutions; the pH decreases by {approximately} 1 pH unit with each test, until the final pH is {approximately}2. Sludges precipitated by all reagents had very similar leachabilities except for KB-1 and Bauxsol, which released more aluminum. SALT showed that lowering the pH of the leaching solution mobilized more metals from the sludges. Iron, aluminum, copper, and zinc began to leach at pH 2.5-3, {approximately}4.5, {approximately}5.5, and 6-6.5, respectively. The leachability of ARD treatment sludges is determined by the final pH of the leachate. A higher neutralization potential (e.g., a greater content of unreacted neutralizing agent) makes sludges inherently more chemically stable. Thus, when ARD or any acidic metalliferous wastewater is treated, a choice must be made between efficient reagent use and resistance to acid attack. 26 refs., 5 figs., 2 tabs.

  9. Chemical stability of acid rock drainage treatment sludge and implications for sludge management.

    PubMed

    McDonald, Danny M; Webb, John A; Taylor, Jeff

    2006-03-15

    To assess the chemical stability of sludges generated by neutralizing acid rock drainage (ARD) with alkaline reagents, synthetic ARD was treated with hydrated lime (batch and high-density sludge process), limestone, and two proprietary reagents (KB-1 and Bauxsol). The amorphous metal hydroxide sludge produced was leached using deionized water, U.S. EPA methods (toxicity characteristic leaching procedure, synthetic precipitation leaching procedure), and the new strong acid leach test (SALT), which leaches the sludge with a series of sulfuric acid extractant solutions; the pH decreases by approximately 1 pH unit with each test, until the final pH is approximately 2. Sludges precipitated by all reagents had very similar leachabilities except for KB-1 and Bauxsol, which released more aluminum. SALT showed that lowering the pH of the leaching solution mobilized more metals from the sludges. Iron, aluminum, copper, and zinc began to leach at pH 2.5-3, approximately 4.5, approximately 5.5, and 6-6.5, respectively. The leachability of ARD treatment sludges is determined by the final pH of the leachate. A higher neutralization potential (e.g., a greater content of unreacted neutralizing agent) makes sludges inherently more chemically stable. Thus, when ARD or any acidic metalliferous wastewater is treated, a choice must be made between efficient reagent use and resistance to acid attack.

  10. Mechanism of Mesozoic Volcanism in Northeastern China: Evidence from New Distribution Maps of Volcanic Rock and Petrogenesis of Acid Rock in Deep Songliao Basin

    NASA Astrophysics Data System (ADS)

    Meng, Fanchao; Liu, Jiaqi; Rasskazov, Sergei; Gao, Jinliang; Zhang, Yutao

    2014-05-01

    Northeastern China is located in the eastern segment of the Central Asian Orogenic belt, which is characterized by widespread Mesozoic volcanic rocks. At present, there are two different opinions concerning the mechanism of volcanism: one proposal is that volcanism was associated with the closure of Mongolia-Okhotsk (MO) Bay, but another suggestion is that the Mesozoic volcanism is controlled by the subduction of Paleo-Pacific plate. However, most studies have mainly focused on the Mesozoic volcanic rocks in Great Xing'an Range(GXR), lack of evidence from Songliao Basin. In order to exactly reveal the mechanism of volcanic rocks in Northeastern China, five new distribution maps of volcanic rocks in Northeast China are drawn and petrogenesis of Mesozoic volcanic rocks in Songliao Basin are obtained. Based on 1: 50000 geological maps, five distribution maps of volcanic rocks (1:2000000) in Northeastern China are recompiled: Early Jurassic, Middle Jurassic, Late Jurassic, Early Cretaceous, and Late Cretaceous. The Early Jurassic volcanic rocks predominantly occur in the eastern Heilongjiang-Jilin province, with minor in Manzhouli in the western. The Middle Jurassic volcanic rocks are mainly founded in the western Liaoning provinces. The Early-Middle Jurassic volcanic rocks(170-146Ma) belong chemically to sub-alkaline series, implying an active continental margin setting. The Late Jurassic volcanic rocks(146-122Ma) mainly occur in the western GXR area, and the magma derived from enriched lithospheric mantle which is closely associated with the subduction of MO plate. The Early Cretaceous volcanic rocks(122-102Ma), widespread in GXR and Songliao basin, are mainly acid and erupt in extensional setting, probably associated with the lithospheric thinning and asthenospheric mantle upwelling caused by subduction of the Paleo-Pacific plate beneath eastern China. Constraints on the timing of MO Bay closure and the motion direction of Paleo-Pacific plate, we infer that:(1) In

  11. An Investigation of the Acid Rock Drainage Generation from the Road Cut Slope in the Middle Part of South Korea

    NASA Astrophysics Data System (ADS)

    Ji, S.; Cheong, Y.; Yim, G.

    2006-05-01

    To examine the Acid Rock Drainage (ARD) generation from the road cut slope, a prediction study including Acid-Base Accounting (ABA) test and Net Acid Generation (NAG) test was performed for road cut rock samples (20 samples) at the new construction site of a highway in the middle part of South Korea. This slope is composed of slate and phyllite. It was a pit wall which was operated as a quarry which produced materials for roofing. pH1:2 and EC1:2 measurements were performed to evaluate free hydrogen ion contents and salts in samples. ABA test was performed to estimate the balance of the acid generating minerals (mainly pyrite) and the acid neutralizing minerals (mainly carbonates) in rock samples. Total sulfur was analyzed by sulfur analyzer, and then the maximum potential acidity (MPA, kg H2SO4/t) was calculated. X-ray diffraction (XRD) analysis was performed to identify the mineral composition of rock samples. Acid neutralizing capacity (ANC) test, after the Sobek et al. (1978), was performed to estimate the amount of acid originated from the oxidation of sulfide minerals. NAPP (Net Acid Producing Potential) was calculated by total sulfur (MPA) and ANC. NAG test was performed with grounded samples and 15 % hydrogen peroxide, and then NAG was analyzed by measuring pH (NAGpH) of the mixed solution. pH1:2 and EC1:2 ranged from 2.95 to 7.23 and 17.1 to 3070.0 ¥ìS/cm, respectively. MPA of samples was ranged from 0.0 to 79.9 kg H2SO4/t. From the XRD analysis pyrite was found at the most samples. In the sample from highly weathered dike, goethite was found. Results of the ANC tests indicated that the value of ANC reached up to 59.36 kg H2SO4/t. Rock samples could be classified as Potential Acid Forming rock (PAF) and Non- Acid Forming rock (NAF) by plotting NAPP versus NAGpH. In this study 17 samples were classified as PAF rock. It means that this slope would generate ARD when they reacted with rain. Two samples were grouped as NAF. By application this ARD prediction

  12. Incorporating Geochemical And Microbial Kinetics In Reactive Transport Models For Generation Of Acid Rock Drainage

    NASA Astrophysics Data System (ADS)

    Andre, B. J.; Rajaram, H.; Silverstein, J.

    2010-12-01

    Acid mine drainage, AMD, results from the oxidation of metal sulfide minerals (e.g. pyrite), producing ferrous iron and sulfuric acid. Acidophilic autotrophic bacteria such as Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans obtain energy by oxidizing ferrous iron back to ferric iron, using oxygen as the electron acceptor. Most existing models of AMD do not account for microbial kinetics or iron geochemistry rigorously. Instead they assume that oxygen limitation controls pyrite oxidation and thus focus on oxygen transport. These models have been successfully used for simulating conditions where oxygen availability is a limiting factor (e.g. source prevention by capping), but have not been shown to effectively model acid generation and effluent chemistry under a wider range of conditions. The key reactions, oxidation of pyrite and oxidation of ferrous iron, are both slow kinetic processes. Despite being extensively studied for the last thirty years, there is still not a consensus in the literature about the basic mechanisms, limiting factors or rate expressions for microbially enhanced oxidation of metal sulfides. An indirect leaching mechanism (chemical oxidation of pyrite by ferric iron to produce ferrous iron, with regeneration of ferric iron by microbial oxidation of ferrous iron) is used as the foundation of a conceptual model for microbially enhanced oxidation of pyrite. Using literature data, a rate expression for microbial consumption of ferrous iron is developed that accounts for oxygen, ferrous iron and pH limitation. Reaction rate expressions for oxidation of pyrite and chemical oxidation of ferrous iron are selected from the literature. A completely mixed stirred tank reactor (CSTR) model is implemented coupling the kinetic rate expressions, speciation calculations and flow. The model simulates generation of AMD and effluent chemistry that qualitatively agrees with column reactor and single rock experiments. A one dimensional reaction

  13. Pre-Elsonian mafic magmatism in the Nain Igneous Complex, Labrador: the bridges layered intrusion

    USGS Publications Warehouse

    Ashwal, L.D.; Wiebe, R.A.; Wooden, J.L.; Whitehouse, M.J.; Snyder, Diane

    1992-01-01

    Decades of work on the pristine, unmetamorphosed, and well exposed anorthositic, mafic and granitic rocks of the Nain igneous complex, Labrador, have led to the conclusion that all plutonic rocks in that area were emplaced in a short time intercal at about 1300 ?? 10 Ma). We report here new isotopic data for mafic intrusive rocks that appear to have crystallized several hundred Ma earlier than the bulk of the plutonic activity in the Nain complex. The Bridges layered intrusion (BLI) is a small (15-20 km2) lens of layered mafic rocks about 1.5 km thick, surrounded and intruded by anorthositic, leuconoritic and leucotroctolitic plutons in the middle of the coastal section of the Nain igneous complex. BLI shows very well developed magmatic structures, including channel scours, slump structures, and ubiquitous modally graded layering. Most rocks, however, show granular textures indicative of recrystallization, presumably caused by emplacement of younger anorthositic rocks. BLI contains cumulate rocks with slightly more primitive mineral compositions (An60-83, Fo66-71) than those of other mafic intrusions in the Nain igneous complex, including Kiglapait. SmNd isotopic data for 7 BLI whole-rocks ranging in composition between olivine melagabbro and olivine leucogabbro yield an age of 1667 ?? 75 Ma, which we interpret as the time of primary crystallization. The internal isotopic systematics of the BLI have been reset, probably by intrusion of adjacent anorthositic plutons. A SmNd mineral isochron (plag, whole-rock, mafics) for a BLI olivine melagabbro gives an age of 1283 ?? 22 Ma, equivalent within error of a mineral array (plag, whole-rock, opx, cpx) for an adjacent, igneous-textured, leuconorite vein (1266 ?? 152 Ma). The initial Nd ratio for BLI corresponds to ??{lunate}Nd = -3.18 ?? 0.44. Other whole-rock samples, however, some with vein-like alteration (Chlorite, serpentine, amphiboles), show ??{lunate}Nd values as low as -9.1, suggesting variable contamination by

  14. Zapping Rocks on Mars

    ScienceCinema

    Wiens, Roger

    2016-07-12

    Better understanding Mars means better understanding its geology. That’s why, sitting atop NASA’s Curiosity rover, is ChemCam, an instrument built by Los Alamos National Laboratory that shoots lasers at Martian rocks and analyzes the data. After nearly 1,500 rock zaps, ChemCam has uncovered some surprising facts about the Red Planet, including the discovery of igneous rocks. Soon, a new Los Alamos-built instrument—the SuperCam—will ride aboard the Mars 2020 rover and bring with it enhanced capabilities to unlock new secrets about the planet.

  15. Zapping Rocks on Mars

    SciTech Connect

    Wiens, Roger

    2016-05-16

    Better understanding Mars means better understanding its geology. That’s why, sitting atop NASA’s Curiosity rover, is ChemCam, an instrument built by Los Alamos National Laboratory that shoots lasers at Martian rocks and analyzes the data. After nearly 1,500 rock zaps, ChemCam has uncovered some surprising facts about the Red Planet, including the discovery of igneous rocks. Soon, a new Los Alamos-built instrument—the SuperCam—will ride aboard the Mars 2020 rover and bring with it enhanced capabilities to unlock new secrets about the planet.

  16. Voluminous silicic eruptions during late Permian Emeishan igneous province and link to climate cooling

    NASA Astrophysics Data System (ADS)

    Yang, Jianghai; Cawood, Peter A.; Du, Yuansheng

    2015-12-01

    Silicic eruptive units can constitute a substantive component in flood-basalts-dominated large igneous provinces, but usually constitute only a small proportion of the preserved volume due to poor preservation. Thus, their environmental impact can be underestimated or ignored. Establishing the original volume and potential climate-sensitive gas emissions of silicic eruptions is generally lacking for most large igneous provinces. We present a case study for the ∼260 Ma Emeishan province, where silicic volcanic rocks are a very minor component of the preserved rock archive due to extensive erosion during the Late Permian. Modal and geochemical data from Late Permian sandstones derived from the province suggest that silicic volcanic rocks constituted some ∼30% by volume of the total eroded Emeishan volcanic source rocks. This volume corresponds to > 3 ×104 km3 on the basis of two independent estimate methods. Detrital zircon trace element and Hf isotopic data require the silicic source rocks to be formed mainly by fractional crystallization from associated basaltic magmas. Based on experimental and theoretical calculations, these basalt-derived ∼104 km3 silicic eruptions released ∼1017 g sulfur gases into the higher atmosphere and contribute to the contemporaneous climate cooling at the Capitanian-Wuchiapingian transition (∼260 Ma). This study highlights the potentially important impact on climate of silicic eruptions associated with large igneous province volcanism.

  17. Biochar enhances Aspergillus niger rock phosphate solubilization by increasing organic acid production and alleviating fluoride toxicity.

    PubMed

    Mendes, Gilberto de Oliveira; Zafra, David Lopez; Vassilev, Nikolay Bojkov; Silva, Ivo Ribeiro; Ribeiro, José Ivo; Costa, Maurício Dutra

    2014-05-01

    During fungal rock phosphate (RP) solubilization, a significant quantity of fluoride (F(-)) is released together with phosphorus (P), strongly inhibiting the process. In the present study, the effect of two F(-) adsorbents [activated alumina (Al2O3) and biochar] on RP solubilization by Aspergillus niger was examined. Al2O3 adsorbed part of the F(-) released but also adsorbed soluble P, which makes it inappropriate for microbial RP solubilization systems. In contrast, biochar adsorbed only F(-) while enhancing phosphate solubilization 3-fold, leading to the accumulation of up to 160 mg of P per liter. By comparing the values of F(-) measured in solution at the end of incubation and those from a predictive model, it was estimated that up to 19 mg of F(-) per liter can be removed from solution by biochar when added at 3 g liter(-1) to the culture medium. Thus, biochar acted as an F(-) sink during RP solubilization and led to an F(-) concentration in solution that was less inhibitory to the process. In the presence of biochar, A. niger produced larger amounts of citric, gluconic, and oxalic acids, whether RP was present or not. Our results show that biochar enhances RP solubilization through two interrelated processes: partial removal of the released F(-) and increased organic acid production. Given the importance of organic acids for P solubilization and that most of the RPs contain high concentrations of F(-), the proposed solubilization system offers an important technological improvement for the microbial production of soluble P fertilizers from RP.

  18. Environmental risk assessment of acid rock drainage under uncertainty: The probability bounds and PHREEQC approach.

    PubMed

    Betrie, Getnet D; Sadiq, Rehan; Nichol, Craig; Morin, Kevin A; Tesfamariam, Solomon

    2016-01-15

    Acid rock drainage (ARD) is a major environmental problem that poses significant environmental risks during and after mining activities. A new methodology for environmental risk assessment based on probability bounds and a geochemical speciation model (PHREEQC) is presented. The methodology provides conservative and non-conservative ways of estimating risk of heavy metals posed to selected endpoints probabilistically, while propagating data and parameter uncertainties throughout the risk assessment steps. The methodology is demonstrated at a minesite located in British Columbia, Canada. The result of the methodology for the case study minesite shows the fate-and-transport of heavy metals is well simulated in the mine environment. In addition, the results of risk characterization for the case study show that there is risk due to transport of heavy metals into the environment.

  19. Petrogenesis of Igneous-Textured Clasts in Martian Meteorite Northwest Africa 7034

    NASA Technical Reports Server (NTRS)

    Santos, A. R.; Agee, C. B.; Humayun, M.; McCubbin, F. M.; Shearer, C. K.

    2016-01-01

    The martian meteorite Northwest Africa 7034 (and pairings) is a breccia that samples a variety of materials from the martian crust. Several previous studies have identified multiple types of igneous-textured clasts within the breccia [1-3], and these clasts have the potential to provide insight into the igneous evolution of Mars. One challenge presented by studying these small rock fragments is the lack of field context for this breccia (i.e., where on Mars it formed), so we do not know how many sources these small rock fragments are derived from or the exact formation his-tory of these sources (i.e., are the sources mantle de-rived melt or melts contaminated by a meteorite impactor on Mars). Our goal in this study is to examine specific igneous-textured clast groups to determine if they are petrogenetically related (i.e., from the same igneous source) and determine more information about their formation history, then use them to derive new insights about the igneous history of Mars. We will focus on the basalt clasts, FTP clasts (named due to their high concentration of iron, titanium, and phosphorous), and mineral fragments described by [1] (Fig. 1). We will examine these materials for evidence of impactor contamination (as proposed for some materials by [2]) or mantle melt derivation. We will also test the petrogenetic models proposed in [1], which are igneous processes that could have occurred regardless of where the melt parental to the clasts was formed. These models include 1) derivation of the FTP clasts from a basalt clast melt through silicate liquid immiscibility (SLI), 2) derivation of the FTP clasts from a basalt clast melt through fractional crystallization, and 3) a lack of petrogenetic relationship between these clast groups. The relationship between the clast groups and the mineral fragments will also be explored.

  20. 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.

  1. In situ and experimental evidence for acidic weathering of rocks and soils on Mars

    NASA Astrophysics Data System (ADS)

    Hurowitz, J. A.; McLennan, S. M.; Tosca, N. J.; Arvidson, R. E.; Michalski, J. R.; Ming, D. W.; Schröder, C.; Squyres, S. W.

    2006-01-01

    Experimental data for alteration of synthetic Martian basalts at pH = 0-1 indicate that chemical fractionations at low pH are vastly different from those observed during terrestrial weathering. Rock surface analyses from Gusev crater are well described by the relationships apparent from low-pH experimental alteration data. A model for rock surface alteration is developed, which indicates that a leached alteration zone is present on rock surfaces at Gusev. This zone is not chemically fractionated to a large degree from the underlying rock interior, indicating that the rock surface alteration process has occurred at low water to rock ratio. The geochemistry of natural rock surfaces analyzed by APXS is consistent with a mixture between adhering soil/dust and the leached alteration zone. The chemistry of rock surfaces analyzed after brushing with the RAT is largely representative of the leached alteration zone. The chemistry of rock surfaces analyzed after grinding with the RAT is largely representative of the interior of the rock, relatively unaffected by the alteration process occurring at the rock surface. Elemental measurements from the Spirit, Opportunity, Pathfinder, and Viking 1 landing sites indicate that soil chemistry from widely separated locations is consistent with the low-pH, low water to rock ratio alteration relationships developed for Gusev rocks. Soils are affected principally by mobility of Fe and Mg, consistent with alteration of olivine-bearing basalt and subsequent precipitation of Fe- and Mg-bearing secondary minerals as the primary control on soil geochemistry.

  2. Geochemical Behavior of Selenium in Igneous Systems

    NASA Astrophysics Data System (ADS)

    Jenner, F. E.; Mavrogenes, J. A.; Arculus, R. J.; O'Neill, H. S.

    2008-12-01

    Selenium (Se) is generally assumed to behave much like sulfur (S) in igneous systems. However, it is unclear how valid this assumption is considering that so little is known about the geochemical behaviour of Se. Constraining the range in Se and S concentrations of mantle-derived magmas is important to studies of: core segregation; the composition of late-accreted material; collisional erosion models; processes of mantle melting in various tectonic environments; and recycling of lithospheric components into the mantle, to mention only a few. Previous estimates of the S/Se of primitive and depleted mantle assume that S-Se are similar to Zr-Hf and Nb-Ta in their geochemical coherence, and that S/Se of the Earth's mantle is chondritic (Palme and O"Neill 2003 and references therein). Due to the low abundances of Se in mantle-derived rocks and the lack of calibration materials for routine analysis (i.e. NIST 612), this assumption remains unchallenged. Using a combination of SHRIMP, electron probe, and LA-ICP-MS techniques the concentration of Se in NIST 612 and BCR-2G was obtained to permit rapid in situ LA-ICP-MS analysis of Se concentrations in volcanic glasses. We have obtained Se, S, major and comprehensive trace element data for volcanic glasses from a global range of tectonic settings (mid-ocean ridges, ocean island, island arc and back-arc basins) to improve understanding of the behaviour of Se during igneous processes (e.g. partial melting, fractional crystallisation, and volatile phase separation). Analysis of a range of mid-ocean ridge glasses shows that Se behaves as an incompatible element, but is decoupled from S as the S/Se extends to values well in excess of the chondritic estimate (i.e. 2528; Palme and O"Neill 2003). During back-arc basin and island-arc magmatism, the abundance, systematics and S/Se are diverse. For example, at a specific MgO content, the absolute abundance of Se varies with depletion of the mantle source. Within back-arc suites derived

  3. Immobilization of Zn, Cu, and Pb in contaminated soils using phosphate rock and phosphoric acid.

    PubMed

    Cao, Xinde; Wahbi, Ammar; Ma, Lena; Li, Bing; Yang, Yongliang

    2009-05-30

    Considerable research has been done on P-induced Pb immobilization in Pb-contaminated soils. However, application of P to soils contaminated with multiple heavy metals is limited. The present study examined effectiveness of phosphoric acid (PA) and/or phosphate rock (PR) in immobilizing Pb, Cu, and Zn in two contaminated soils. The effectiveness was evaluated using water extraction, plant uptake, and a simple bioaccessibility extraction test (SBET) mimicking metal uptake in the acidic environment of human stomach. The possible mechanisms for metal immobilization were elucidated using X-ray diffraction, scanning electron microscopy, and chemical speciation program Visual MINTEQ. Compared to the control, all P amendments significantly reduced Pb water solubility, phytoavailability, and bioaccessibility by 72-100%, 15-86%, and 28-92%, respectively. The Pb immobilization was probably attributed to the formation of insoluble Pb phosphate minerals. Phosphorus significantly reduced Cu and Zn water solubility by 31-80% and 40-69%, respectively, presumably due to their sorption on minerals (e.g., calcite and phosphate phases) following CaO addition. However, P had little effect on the Cu and Zn phytoavailability; while the acid extractability of Cu and Zn induced by SBET (pH 2) were even elevated by up to 48% and 40%, respectively, in the H(3)PO(4) treatments (PA and PR+PA). Our results indicate that phosphate was effective in reducing Pb availability in terms of water solubility, bioaccessibility, and phytoavailability. Caution should be exercised when H(3)PO(4) was amended to the soil co-contaminated with Cu and Zn since the acidic condition of SBET increased Cu and Zn bioaccessibility though their water solubility was reduced.

  4. Treatment of acid rock drainage using a sulfate-reducing bioreactor with zero-valent iron.

    PubMed

    Ayala-Parra, Pedro; Sierra-Alvarez, Reyes; Field, James A

    2016-05-05

    This study assessed the bioremediation of acid rock drainage (ARD) in flow-through columns testing zero-valent iron (ZVI) for the first time as the sole exogenous electron donor to drive sulfate-reducing bacteria in permeable reactive barriers. Columns containing ZVI, limestone or a mixture of both materials were inoculated with an anaerobic mixed culture and fed a synthetic ARD containing sulfuric acid and heavy metals (initially copper, and later also cadmium and lead). ZVI significantly enhanced sulfate reduction and the heavy metals were extensively removed (>99.7%). Solid-phase analyses showed that heavy metals were precipitated with biogenic sulfide in the columns packed with ZVI. Excess sulfide was sequestered by iron, preventing the discharge of dissolved sulfide. In the absence of ZVI, heavy metals were also significantly removed (>99.8%) due to precipitation with hydroxide and carbonate ions released from the limestone. Vertical-profiles of heavy metals in the columns packing, at the end of the experiment, demonstrated that the ZVI columns still had excess capacity to remove heavy metals, while the capacity of the limestone control column was approaching saturation. The ZVI provided conditions that enhanced sulfate reduction and generated alkalinity. Collectively, the results demonstrate an innovative passive ARD remediation process using ZVI as sole electron-donor.

  5. Increasing Soluble Phosphate Species by Treatment of Phosphate Rocks with Acidic Waste.

    PubMed

    Santos, Wedisson O; Hesterberg, Dean; Mattiello, Edson M; Vergütz, Leonardus; Barreto, Matheus S C; Silva, Ivo R; Souza Filho, Luiz F S

    2016-11-01

    The development of efficient fertilizers with a diminished environmental footprint will help meet the increasing demand for food and nutrients by a growing global population. Our objective was to evaluate whether an acidic mine waste (AMW) could be used beneficially by reacting it with sparingly soluble phosphate rocks (PRs) to produce more soluble P fertilizer materials. Three PRs from Brazil and Peru were reacted with different concentrations of AMW. Changes in mineralogy and P species were determined using a combination of X-ray diffraction and phosphorus K-edge XANES spectroscopy, in addition to extractable P concentrations. Increasing the AMW concentration typically increased extractable P. X-ray diffraction data showed transformation of apatite to other species when PRs were reacted with AMW at ≥50% (v/v) in water, with gypsum or anhydrite forming at AMW concentrations as low as 12.5%. Linear combination fitting analysis of X-ray absorption near edge structure spectra also indicated a progressive transformation of apatite to noncrystalline Fe(III)-phosphate and more soluble Ca-phosphates with increasing AMW concentration. Because this AMW is costly to dispose of, reacting it with PR to produce a higher-grade phosphate fertilizer material could decrease the environmental impacts of the AMW and diminish the consumption of pure acids in conventional P fertilizer production.

  6. Possible petrogenetic associations among igneous components in North Massif soils: Evidence in 2-4 MM soil particles from 76503

    NASA Astrophysics Data System (ADS)

    Jolliff, Bradley L.; Bishop, Kaylynn M.; Haskin, Larry A.

    1992-12-01

    Studies of Apollo 17 highland igneous rocks and clasts in breccias from the North and South Massifs have described magnesian troctolite, norite, anorthositic gabbro, dunite, spinel cataclasites, and granulitic lithologies that may have noritic anothosite or anorthositic norite/gabbro as igneous precursors, and have speculated on possible petrogenetic relationships among these rock types. Mineral compositions and relative proportions of plagioclase and plagioclase-olivine particles in samples 76503 indicate that the precursor lithology of those particles were troctolitic anorthosite, not troctolite. Mineral and chemical compositions of more pyroxene-rich, magnesian breccias and granulites in 76503 indicate that their precursor lithology was anorthositic norite/gabbro. The combination of mineral compositions and whole-rock trace-element compositional trends supports a genetic relationship among these two groups as would result from differentiation of a single pluton. Although highland igneous lithologies in Apollo 17 materials have been described previously, the proportions of different igneous lithologies present in the massifs, their frequency of association, and how they are related are not well known. We consider the proportions of, and associations among, the igneous lithologies found in a North Massif soil, which may represent those of the North Massif or a major part of it.

  7. Possible petrogenetic associations among igneous components in North Massif soils: Evidence in 2-4 mm soil particles from 76503

    NASA Technical Reports Server (NTRS)

    Jolliff, Bradley L.; Bishop, Kaylynn M.; Haskin, Larry A.

    1992-01-01

    Studies of Apollo 17 highland igneous rocks and clasts in breccias from the North and South Massifs have described magnesian troctolite, norite, anorthositic gabbro, dunite, spinel cataclasites, and granulitic lithologies that may have noritic anothosite or anorthositic norite/gabbro as igneous precursors, and have speculated on possible petrogenetic relationships among these rock types. Mineral compositions and relative proportions of plagioclase and plagioclase-olivine particles in samples 76503 indicate that the precursor lithology of those particles were troctolitic anorthosite, not troctolite. Mineral and chemical compositions of more pyroxene-rich, magnesian breccias and granulites in 76503 indicate that their precursor lithology was anorthositic norite/gabbro. The combination of mineral compositions and whole-rock trace-element compositional trends supports a genetic relationship among these two groups as would result from differentiation of a single pluton. Although highland igneous lithologies in Apollo 17 materials have been described previously, the proportions of different igneous lithologies present in the massifs, their frequency of association, and how they are related are not well known. We consider the proportions of, and associations among, the igneous lithologies found in a North Massif soil, which may represent those of the North Massif or a major part of it.

  8. Magmatic systems of large continental igneous province

    NASA Astrophysics Data System (ADS)

    Sharkov, Evgenii

    2014-05-01

    Large igneous provinces (LIPs) of the modern type are known from the middle Paleoproterozoic and have a great abundance in the Phanerozoic. The most researches considered their appearance with ascending of the mantle thermochemical superplumes which provided simultaneously eruption of the same type of lavas on the huge territories. Judging on presence among them different subprovinces, formation of concrete magmatic systems were linked with protuberances (secondary plumes) on the superplumes surfaces. We suggest that origin of such plumes was linked with local enrichment of upper part of the superplumes head beneath roofing by fluid components; it led to lowering of the plume material density and initiated ascending of the secondary plumes. As a result, their heads, where partial melting occurred, can reach the level of the upper crust as it follows from absence of lower-crustal rocks among xenoliths in basalts, although mantle xenoliths existed in them. Important feature of LIPs is presence of two major types of mafic lavas: (1) geochemical-enriched alkali Fe-Ti basalts and picrites, and (2) basalts of normal alkalinity (tholeiites) with different contents of TiO2. At that the first type of mafites are usually typical for lower parts of LIPs which initially developed as continental rifts, whereas the second type composed the upper part of the traps' cover. Magmatic systems of the LIPs are subdivided on three levels of different deep: (1) zones of magma generation, (2) areas of transitional magma chambers where large often layered intrusive bodies are formed, and (3) areas on surface where lava eruptions and subvolcanic intrusions occurred. All these levels are linked by feeder dykes. The least known element of the system is area of magma generation, and, especially, composition of melting substratum. Important information about it is contained in aforementioned mantle xenoliths in alkali basalts and basanites. They practically everywhere are represented by two

  9. Application of multi-dimensional discrimination diagrams and probability calculations to Paleoproterozoic acid rocks from Brazilian cratons and provinces to infer tectonic settings

    NASA Astrophysics Data System (ADS)

    Verma, Sanjeet K.; Oliveira, Elson P.

    2013-08-01

    In present work, we applied two sets of new multi-dimensional geochemical diagrams (Verma et al., 2013) obtained from linear discriminant analysis (LDA) of natural logarithm-transformed ratios of major elements and immobile major and trace elements in acid magmas to decipher plate tectonic settings and corresponding probability estimates for Paleoproterozoic rocks from Amazonian craton, São Francisco craton, São Luís craton, and Borborema province of Brazil. The robustness of LDA minimizes the effects of petrogenetic processes and maximizes the separation among the different tectonic groups. The probability based boundaries further provide a better objective statistical method in comparison to the commonly used subjective method of determining the boundaries by eye judgment. The use of readjusted major element data to 100% on an anhydrous basis from SINCLAS computer program, also helps to minimize the effects of post-emplacement compositional changes and analytical errors on these tectonic discrimination diagrams. Fifteen case studies of acid suites highlighted the application of these diagrams and probability calculations. The first case study on Jamon and Musa granites, Carajás area (Central Amazonian Province, Amazonian craton) shows a collision setting (previously thought anorogenic). A collision setting was clearly inferred for Bom Jardim granite, Xingú area (Central Amazonian Province, Amazonian craton) The third case study on Older São Jorge, Younger São Jorge and Maloquinha granites Tapajós area (Ventuari-Tapajós Province, Amazonian craton) indicated a within-plate setting (previously transitional between volcanic arc and within-plate). We also recognized a within-plate setting for the next three case studies on Aripuanã and Teles Pires granites (SW Amazonian craton), and Pitinga area granites (Mapuera Suite, NW Amazonian craton), which were all previously suggested to have been emplaced in post-collision to within-plate settings. The seventh case

  10. The role of igneous sills in shaping the Martian uplands

    NASA Technical Reports Server (NTRS)

    Wilhelms, D. E.; Baldwin, R. J.

    1989-01-01

    Relations among geologic units and landforms suggest that igneous sills lie beneath much of the intercrater and intracrater terrain of the Martian uplands. The igneous rocks crop out along the upland-lowland front and in crater floors and other depressions that are low enough to intersect the sill's intrusion horizons. It is suggested that heat from the cooling sills melted some of the ice contained in overlying fragmental deposits, creating valley networks by subsurface flow of the meltwater. Terrains with undulatory, smooth surfaces and softened traces of valleys were created by more direct contact with the sills. Widespread subsidence following emplacement of the sills deformed both them and the nonvolcanic deposits that overlie them, accounting for the many structures that continue from ridged plains into the hilly uplands. Crater counts show that the deposit that became valleyed, softened, and ridged probably began to form (and to acquire interstitial ice) during or shortly after the Middle Noachian Epoch, and continued to form as late as the Early Hesperian Epoch. The upper layers of this deposit, many of the visible valleys, and the ridged plains and postulated sills all have similar Early Hesperian ages. Continued formation of valleys is indicated by their incision of fresh-appearing crater ejecta. The dependence of valley formation on internal processes implies that Mars did not necessarily have a dense early atmosphere or warm climate.

  11. Post-igneous redistribution of components in eucrites

    NASA Technical Reports Server (NTRS)

    Phinney, W. C.; Lindstrom, D. J.; Mittlefehldt, D. W.; Martinez, R. R.

    1993-01-01

    In our analyses, we utilize a microdrilling technique that removes 40 to 100 micron diameter cores from mineral grains in thin sections analyzed by microprobe. The cores are then analyzed by INAA using the technique of Lindstrom. Three eucrites were selected for application of this analytical technique: monomict breccias Pasamonte and Stannern and unbrecciated EET90020. Pasamonte is among the most unequilibrated of the eucrites on the basis of zoning in pyroxenes and is considered to be an igneous rock not significantly affected by metamorphism. Stannern has igneous texture but its pyroxenes indicate some re-equilibration, although little, if any, recrystallization. EET90020 has a granulite texture and has been substantially recrystallized. Our sample of Pasamonte contains several clasts of different grain sizes ranging from glass to fine grained with diabasic texture containing lathy plagioclase, unexsolved pigeonite, and mesostasis. Cores were taken of the glass and from minerals and mesostases in six lithic clasts which normally allowed sampling of more than one phase per clast. Our sample of Stannern is also a breccia but with little difference in grain size between clasts and matrix. The plagioclase and pigeonite are blocky, twinned, and exsolved and coexist with a bit of mesostasis. Cores were taken of plagioclase and pigeonite with no attempt to distinguish separate clasts. EET90020 is a granular mixture of twinned plagioclase and pigeonite having rather uniform size and many triple junctions. Several cores were taken of both phases. Both clear and cloudy grains of plagioclase and pyroxene were sampled in all three eucrites.

  12. Tectonic significance of Neoproterozoic magmatism of Nakora area, Malani igneous suite, Western Rajasthan, India

    NASA Astrophysics Data System (ADS)

    Kumar, Naresh; Vallinayagam, G.

    2014-05-01

    Three magmatic phases are distinguished in the Neoproterozoic Nakora Ring Complex (NRC) of Malani Igneous Suite (MIS), namely (a) Extrusive (b) Intrusive and (c) Dyke phase. Magmatism at NRC initiated with minor amount of (basic) basalt flows and followed by the extensive/voluminous acid (rhyolites-trachytes) flows. The ripple marks are observed at the Dadawari area of NRC in tuffaceous rhyolite flow which suggests the aqueous condition of flows deposition. The emplacement of the magma appears to have been controlled by a well defined NE-SW tectonic lineament and cut by radial pattern of dykes. These NE-SW tectonic lineaments are the linear zones of crustal weakness and high heat flow. The spheroidal and rapakivi structures in the Nakora acid volcanics indicate the relationship between genetic link and magma mixing. Basalt-trachyte-rhyolite association suggests that the large amount of heat is supplied to the crust from the magma chamber before the eruption. The field (elliptical/ring structures), mineralogical and geochemical characteristics of Nakora granites attest an alkaline character in their evolution and consistent with within plate tectonic setting. The emplacement of these granites and associated volcanics is controlled by ring structures, a manifestation of plume activity and cauldron subsidence, an evidence of extensional tectonic environment. NRC granites are the product of partial melting of rocks similar to banded gneiss from Kolar Schist Belt of India. The present investigations suggest that the magmatic suites of NRC rocks are derived from a crustal source and the required heat supplied from a mantle plume.

  13. Lunar highland rock types: Their implications for impact induced fractionation

    NASA Technical Reports Server (NTRS)

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

    1974-01-01

    The first step in a petrologic study must be a classification based on observed textures and mineralogy. Lunar rocks, may be classified into three major groups: (1) coarse-grained igneous rocks, (2) fine-grained igneous rocks and (3) breccias. Group 1 is interpreted as primitive lunar crustal rocks that display various degrees of crushing and/or annealing. Group 2 is interpreted as volcanic rocks. Group 3 is interpreted as resulting from impacts on the lunar surface and is subdivided on the basis of matrix textures into fragmental breccias, crystalline breccias that have been annealed, and crystalline breccias with igneous matrices. A synthesis of the relevant data concerning lunar highlands polymict breccias from the fields of petrography, chemistry, photogeology, and impact studies compels the prediction that the breccias should have homogeneous matrices from rock to rock within regions of the highlands of limited size where impact mixing has been efficient and extensive.

  14. Variations in magmatic processes among igneous asteroids

    NASA Technical Reports Server (NTRS)

    Gaffey, M. J.

    1991-01-01

    Six asteroid classes (types V, E, A, R, M, S) are composed primarily of differentiated assemblages produced by igneous processes within their parent planetesimals. These are identified by surface materials which deviate from a chondritic composition to a degree that require igneous chemical fractionation processes. There are large variations among these igneous asteroids in the peak temperatures attained, in the efficiency of magmatic phase separation, and in the depth within the original parent body exposed at the present surface. These variations provide important constraints on the nature of asteroidal heating events, on the differentiation processes within small planetary bodies, and on the disruption of those parent bodies. Variations due to depth within the parent body and due to degree of magmatic differentiation are detailed.

  15. In-Situ and Experimental Evidence for Acidic Weathering of Rocks and Soils on Mars

    NASA Technical Reports Server (NTRS)

    Hurowitz, J. A.; McLennan, S. M.; Tosca, N. J.; Arvidson, R. E.; Michalski, J. R.; Ming, D.; Schroeder, C.; Squyres, S. W.

    2006-01-01

    Experimental data for alteration of synthetic Martian basalts at pH=0-1 indicate that chemical fractionations at low pH are vastly different from those observed during terrestrial weathering. Rock analyses from Gusev crater are well described by the relationships apparent from low pH experimental alteration data. A model for rock surface alteration is developed which indicates that a leached alteration zone is present on rock surfaces at Gusev. This zone is not chemically fractionated to a large degree from the underlying rock interior, indicating that the rock surface alteration process has occurred at low fluid-to-rock ratio. The geochemistry of natural rock surfaces analyzed by APXS is consistent with a mixture between adhering soil/dust and the leached alteration zone. The chemistry of rock surfaces analyzed after brushing with the RAT is largely representative of the leached alteration zone. The chemistry of rock surfaces analyzed after grinding with the RAT is largely representative of the interior of the rock, relatively unaffected by the alteration process occurring at the rock surface. Elemental measurements from the Spirit, Opportunity, Pathfinder and Viking 1 landing sites indicate that soil chemistry from widely separated locations is consistent with the low-pH, low fluid to rock ratio alteration relationships developed for Gusev rocks. Soils are affected principally by mobility of FeO and MgO, consistent with alteration of olivine-bearing basalt and subsequent precipitation of FeO and MgO bearing secondary minerals as the primary control on soil geochemistry.

  16. Evaluation of net acid generation pH as a single indicator for acid forming potential of rocks using geochemical properties.

    PubMed

    Oh, Chamteut; Ji, Sangwoo; Yim, Giljae; Cheong, Youngwook

    2017-04-01

    The main purpose of this research was to evaluate the geochemical properties of rocks for a single indicator of acid-forming potential. The indicators, such as net acid generation (NAG), NAG pH and total S, were applied to 312 rock samples of various geological characteristics. Additional indicators, such as a Modified NAG pH, paste pH and available acid neutralizing capacity (ANC), were applied to 22 selected samples. Among them, NAG pH was considered the most plausible single indicator in evaluating acid-forming potential, as it is simple to measure, widely applicable to various samples and can be used to estimate the NAG value. The acid-forming potential of 287 samples (92% of samples examined in this research) was classified as either non-acid forming (NAF) or potentially acid forming (PAF) by NAG pH, with an NAF criteria of <3.21 and PAF of >4.52. The NAG pH was also a good estimate of the risk of short-term acid release when combined with paste pH information. However, application of NAG pH to coal mine wastes, with high organic carbon contents, produced erroneous results due to the generation of organic acid during the NAG test. In this research, a Modified NAG pH was assessed as an alternative to NAG pH in such situations.

  17. Oil sands thickened froth treatment tailings exhibit acid rock drainage potential during evaporative drying.

    PubMed

    Kuznetsov, Petr; Kuznetsova, Alsu; Foght, Julia M; Siddique, Tariq

    2015-02-01

    Bitumen extraction from oil sands ores after surface mining produces different tailings waste streams: 'froth treatment tailings' are enriched in pyrite relative to other streams. Tailings treatment can include addition of organic polymers to produce thickened tailings (TT). TT may be further de-watered by deposition into geotechnical cells for evaporative drying to increase shear strength prior to reclamation. To examine the acid rock drainage (ARD) potential of TT, we performed predictive analyses and laboratory experiments on material from field trials of two types of thickened froth treatment tailings (TT1 and TT2). Acid-base accounting (ABA) of initial samples showed that both TT1 and TT2 initially had net acid-producing potential, with ABA values of -141 and -230 t CaCO₃ equiv. 1000 t(-1) of TT, respectively. In long-term kinetic experiments, duplicate ~2-kg samples of TT were incubated in shallow trays and intermittently irrigated under air flow for 459 days to simulate evaporative field drying. Leachates collected from both TT samples initially had pH~6.8 that began decreasing after ~50 days (TT2) or ~250 days (TT1), stabilizing at pH~2. Correspondingly, the redox potential of leachates increased from 100-200 mV to 500-580 mV and electrical conductivity increased from 2-5 dS m(-1) to 26 dS m(-1), indicating dissolution of minerals during ARD. The rapid onset and prolonged ARD observed with TT2 is attributed to its greater pyrite (13.4%) and lower carbonate (1.4%) contents versus the slower onset of ARD in TT1 (initially 6.0% pyrite and 2.5% carbonates). 16S rRNA gene pyrosequencing analysis revealed rapid shift in microbial community when conditions became strongly acidic (pH~2) favoring the enrichment of Acidithiobacillus and Sulfobacillus bacteria in TT. This is the first report showing ARD potential of TT and the results have significant implications for effective management of pyrite-enriched oil sands tailings streams/deposits.

  18. Dealumination of clinoptilolite and its effect on zinc removal from acid rock drainage.

    PubMed

    Xu, Wanjing; Li, Loretta Y; Grace, John R

    2014-09-01

    Clinoptilolite, a natural zeolite, is capable of removing heavy metals from acid rock drainage (ARD). Previous studies have neglected the dealumination of clinoptilolite and its impact during remediation. This study observed the dealumination of clinoptilolite during ARD remediation in a slurry bubble column (SBC), and investigated its impact on the capture of zinc. Uptake tests were performed with natural ARD and various sorbent average particle diameters from 300 to 1400μm, superficial gas velocities from 0.08 to 0.23ms(-1), initial aqueous pH from 2 to 6, Zn concentrations from 15 to 215ppm and sorbent/solution mass ratios from 25 to 400gkg(-1) to test zinc uptake. Dealumination of clinoptilolite was sometimes observed during the uptake process. Increased Al in the aqueous phase led to co-precipitation of Zn-Al colloid, enhanced by abundant sulfate in solution. The unit zinc uptake of the Al colloid was found to be much higher than for the raw clinoptilolite.

  19. Enriching acid rock drainage related microbial communities from surface-deposited oil sands tailings.

    PubMed

    Dean, Courtney; Xiao, Yeyuan; Roberts, Deborah J

    2016-10-01

    Little is known about the microbial communities native to surface-deposited pyritic oil sands tailings, an environment where acid rock drainage (ARD) could occur. The goal of this study was to enrich sulfur-oxidizing organisms from these tailings and determine whether different populations exist at pH levels 7, 4.5, and 2.5. Using growth-based methods provides model organisms for use in the future to predict potential activities and limitations of these organisms and to develop possible control methods. Thiosulfate-fed enrichment cultures were monitored for approximately 1 year. The results showed that the enrichments at pH 4.5 and 7 were established quicker than at pH 2.5. Different microbial community structures were found among the 3 pH environments. The sulfur-oxidizing microorganisms identified were most closely related to Halothiobacillus neapolitanus, Achromobacter spp., and Curtobacterium spp. While microorganisms related to Chitinophagaceae and Acidocella spp. were identified as the only possible iron-oxidizing and -reducing microbes. These results contribute to the general knowledge of the relatively understudied microbial communities that exist in pyritic oil sands tailings and indicate these communities may have a potential role in ARD generation, which may have implications for future tailings management.

  20. Algae as an electron donor promoting sulfate reduction for the bioremediation of acid rock drainage.

    PubMed

    Ayala-Parra, Pedro; Sierra-Alvarez, Reyes; Field, Jim A

    2016-11-05

    This study assessed bioremediation of acid rock drainage in simulated permeable reactive barriers (PRB) using algae, Chlorella sorokiniana, as the sole electron donor for sulfate-reducing bacteria. Lipid extracted algae (LEA), the residues of biodiesel production, were compared with whole cell algae (WCA) as an electron donor to promote sulfate-reducing activity. Inoculated columns containing anaerobic granular sludge were fed a synthetic medium containing H2SO4 and Cu(2+). Sulfate, sulfide, Cu(2+) and pH were monitored throughout the experiment of 123d. Cu recovered in the column packing at the end of the experiment was evaluated using sequential extraction. Both WCA and LEA promoted 80% of sulfate removal (12.7mg SO4(2-) d(-1)) enabling near complete Cu removal (>99.5%) and alkalinity generation raising the effluent pH to 6.5. No noteworthy sulfate reduction, alkalinity formation and Cu(2+) removal were observed in the endogenous control. In algae amended-columns, Cu(2+) was precipitated with biogenic H2S produced by sulfate reduction. Formation of CuS was evidenced by sequential extraction and X-ray diffraction. LEA and WCA provided similar levels of electron donor based on the COD balance. The results demonstrate an innovative passive remediation system using residual algae biomass from the biodiesel industry.

  1. Reclamation of acidic, denuded copper basin land: Revegetation performance of phosphate rock vs other nutrient sources

    SciTech Connect

    Soileau, J.M.; Sikora, F.J.; Maddox, J.J.; Kelsoe, J.J.

    1996-12-31

    Open pit smelting of Copper ore about 100 years ago resulted in approximately 9,300 ha of severely eroded, very acidic (pH 4.0 to 5.0) soils at Copper Basin, Tennessee. Along with other essential nutrients, phosphorus (P) amendments are critical for long-term productivity and sustainability of vegetation on this depleted soil. A field study was conducted (1992-1995) to compare revegetation from surface-applied North Carolina phosphate rock (PR) and triple superphosphate (TSP) at 20, 59, and 295 kg P ha{sup -1}, and to determine benefits of starter NPK tree tablets. The experimental design consisted of 7.3 x 9.1 m replicated plots, each planted to 20 loblolly pine seedlings and aerially seeded with a mixture of grasses and legumes. Tree survivability was high from all treatments. Through the third year, tree height and diameter increased with increasing P to 59 kg P ha without fertilizer tablets. There were no pine growth differences between PR and TSP. Weeping lovegrass has been the dominant cover crop through 1995, with increased stimulation to tree tablets and surface P. Tall fescue (KY 31), sericea lespedeza, and black locust responded more to PR than to TSP. Surface soil pH increased, and 0.01 M SrCl{sub 2} extractable Al decreased, with increasing rate of PR. For future loblolly pine plantings in the Copper Basin, this study suggests there is no benefit to applying both tree tablets and surface P at rates above 59 kg P ha{sup -1}. For reclaiming land with high acidity and low P fertility, PR has significant benefits. In reclaiming steep, gullied land, there is great potential for aerial application of PR and/or pelletized liming agents.

  2. Trace metal mobilization from oil sands froth treatment thickened tailings exhibiting acid rock drainage.

    PubMed

    Kuznetsova, Alsu; Kuznetsov, Petr; Foght, Julia M; Siddique, Tariq

    2016-11-15

    Froth treatment thickened tailings (TT) are a waste product of bitumen extraction from surface-mined oil sands ores. When incubated in a laboratory under simulated moist oxic environmental conditions for ~450d, two different types of TT (TT1 and TT2) exhibited the potential to generate acid rock drainage (ARD) by producing acid leachate after 250 and 50d, respectively. We report here the release of toxic metals from TT via ARD, which could pose an environmental threat if oil sands TT deposits are not properly managed. Trace metal concentrations in leachate samples collected periodically revealed that Mn and Sr were released immediately even before the onset of ARD. Spikes in Co and Ni concentrations were observed both pre-ARD and during active ARD, particularly in TT1. For most elements measured (Fe, Cr, V, As, Cu, Pb, Zn, Cd, and Se), leaching was associated with ARD production. Though equivalent acidification (pH2) was achieved in leachate from both TT types, greater metal release was observed from TT2 where concentrations reached 10,000ppb for Ni, 5000ppb for Co, 3000ppb for As, 2000ppb for V, and 1000ppb for Cr. Generally, metal concentrations decreased in leachate with time during ARD and became negligible by the end of incubation (~450d) despite appreciable metals remaining in the leached TT. These results suggest that using TT for land reclamation purposes or surface deposition for volume reduction may unfavorably impact the environment, and warrants application of appropriate strategies for management of pyrite-enriched oil sands tailings streams.

  3. Did North Atlantic Igneous Province igneous sills trigger or maintain Paleocene Eocene Thermal Maximum global warming?

    NASA Astrophysics Data System (ADS)

    Fernandes, Karina; Jones, Stephen M.; Schofield, Nick; Clayton, Geoff

    2010-05-01

    Igneous sills of the North Atlantic Igneous Province (NAIP) were intruded into organic-rich sediments, generating methane and carbon dioxide by thermal maturation. These greenhouse gases escaped to the ocean and atmosphere through hydrothermal vents above the sills that have been observed on seismic reflection data and by drilling. It has been suggested that the NAIP sills provided a significant component of the greenhouse gases that forced warming during the Paleocene Eocene Thermal Maximum (PETM). Here we consider whether methane released by NAIP sills could have triggered, as well as maintained, the PETM warming. Warming resulting from the PETM trigger began a few thousand years before the major upheaval in the carbon cycle that was associated with the PETM itself. Recent organic geochemical investigations have suggested that methane was involved in the trigger. Since the lifetime of methane in the atmosphere was approximately one decade during the Paleocene, the triggering methane pulse probably contained on the order of 100 Gt or more of carbon and was probably released in a period of c. 10 years or less. We use recent field observations of fluidized country rocks around sills to speculate on a model for sill emplacement, greenhouse gas generation and escape. The observation of fluidized sediments associated with lobe and finger structures along inward-dipping sections of many sills suggests that these sill rims propagated laterally by fluidizing a restricted volume of country rock, allowing the magma to advance into the fluidized region as a viscous fingering front. At this stage, the fluidized region was not connected to the surface by a conduit, so greenhouse gases could not escape rapidly. Eventually, as the sill rim propagated laterally and upward, a hydrothermal conduit was initiated and propagated rapidly upward to the surface. This model, based on field observations implies that the gases which initially escaped up the hydrothermal conduit were

  4. Magmatic Evolution of the Skye Igneous Center, Western Scotland

    NASA Astrophysics Data System (ADS)

    Fowler, S. J.; Bohrson, W. A.; Spera, F. J.

    2003-12-01

    Geochemically complex igneous suites are the result of interplay between deep and crustal-level processes. Quantitatively modeling the contribution that crustal-level processes such as magma recharge, crustal assimilation, and fractional crystallization have is critical for developing realistic models of how magma transport/storage systems evolve. The Energy-Constrained Recharge, Assimilation, and Fractional Crystallization simulator (EC-RAFC, Spera & Bohrson, 2001, 2002; Bohrson & Spera, 2001, 2003) provides a means to model thermal, compositional, and magma volume data for complex magmatic systems. The Skye igneous center, western Scotland, spanning the period 60.53 +/- 0.08 Ma - 53.5 +/- 0.8 Ma and characterized by a well-documented suite of lavas and intrusive rocks of picritic to granitic composition, is the first natural data set to which the EC-RAFC model has been applied in detail. Based on analysis of published field, stratigraphic, petrographic, and chemical data, we propose that the Skye Tertiary magmatic sequence be divided into four petrogenetically related lineages. EC-RAFC results indicate that each lineage is characterized by a unique parental magma that has undergone distinct episodes of RAFC. Model results, constrained by published data on the nature of the crust beneath Skye, indicate that the character of the assimilant changes upsection, suggesting that the associated magma reservoirs migrated to shallower levels as the magmatic system matured. The magmatic products of each group also record the fingerprint of multiple episodes of magma recharge, where the character of the recharge magma also evolves with time. The image of the magma transport system that emerges is one in which magma is initially intruded at lower crustal levels and undergoes a distinct RAFC episode. Residual magma from this event then migrates to shallower levels, where mid-crustal wallrock is assimilated; recharge magma is characterized by increasingly crustal chemical and

  5. Acid Fluid-Rock Interactions with Shales Comprising Unconventional Hydrocarbon Reservoirs and with Shale Capping Carbon Storage Reservoirs: Experimental Insights

    NASA Astrophysics Data System (ADS)

    Kaszuba, J. P.; Bratcher, J.; Marcon, V.; Herz-Thyhsen, R.

    2015-12-01

    Injection of HCl is often a first stage in the hydraulic fracturing process. These acidic fluids react with marls or shales in unconventional reservoirs, reactions generally comparable to reaction between shale caprocks and acidic, carbonated formation waters in a carbon storage reservoir. Hydrothermal experiments examine acid fluid-rock interaction with 1) an unconventional shale reservoir and 2) a model shale capping a carbon storage reservoir. In the former, unconventional reservoir rock and hydraulic fracturing fluid possessing a range of ionic strengths (I = 0.01, 0.15) and initial pH values (2.5 and 7.3) reacted at 115°C and 35 MPa for 28 days. In the latter, a model carbon storage reservoir (Fe-rich dolomite), shale caprock (illite), and shale-reservoir mixture each reacted with formation water (I = 0.1 and pH 6.3) at 160°C and 25 MPa for ~15 days. These three experiments were subsequently injected with sufficient CO2 to maintain CO2 saturation in the water and allowed to react for ~40 additional days. Acidic frac fluid was rapidly buffered (from pH 2.5 to 6.2 after 38 hrs) by reaction with reservoir rock whereas the pH of near-neutral frac fluid decreased (from 7.3 to 6.9) after 47 hrs. Carbonate dissolution released Ca and Sr into solution and feldspar dissolution released SiO2 and Li; the extent of reaction was greater in the experiment containing acidic frac fluid. All three carbon storage experiments displayed a similar pH decrease of 1.5 units after the addition of CO2. The pH remained low for the duration of the experiments because the immiscible supercritical CO2 phase provided an infinite reservoir of carbonic acid that could not be consumed by reaction with the rock. In all three experiments, Ca, Fe, Mg, Mn and SO4 increase with injection, but slowly decline through termination of the experiments. This trend suggests initial dissolution followed by re-precipitation of carbonates, which can be seen in modeling and SEM results. New clay minerals

  6. UThPb age of Apollo 12 rock 12013

    USGS Publications Warehouse

    Tatsumoto, M.

    1970-01-01

    A UThPb isotopic study of three chips from lunar rock 12013 indicates that parental material of the intrusion breccia formed quite early in the moon's history, possibly 3.9 to 4.3 by ago. The UThPb characteristics of the rock are distinctly different from those of other Apollo 12 igneous rocks and suggest a different origin. ?? 1970.

  7. Radiological, chemical and morphological characterizations of phosphate rock and phosphogypsum from phosphoric acid factories in SW Spain.

    PubMed

    Rentería-Villalobos, Marusia; Vioque, Ignacio; Mantero, Juan; Manjón, Guillermo

    2010-09-15

    In this work, radiological, chemical, and also morphological characterization was performed in phosphate rock and phosphogypsum samples, in order to understand the behavior of toxic elements. Characterization was carried out using X-ray diffraction (XRD), X-ray fluorescence (XRF), gamma spectrometry and scanning electron microscopy with energy-dispersive X-ray analysis (SEM-EDX). Our results show that the phosphate rock was mainly composed of fluorapatite, calcite, perovskite, quartz, magnetite, pyrite and kaolinite, whereas phosphogypsum only exhibited dihydrated calcium sulfate. The activity concentration of U-series radioisotopes in phosphate rock was around 1640 Bq/kg. (226)Ra and (210)Pb tend to be distributed into phosphogypsum by up to 80%, whereas the fraction of U-isotopes is 10%. The most abundant trace elements in phosphate rock were Sr, Cr, V, Zn, Y, Ni and Ba. Some elements, such as Ba, Cd, Cu, La, Pb, Se, Sr, Th and Y, were enriched in the phosphogypsum. This enrichment may be attributed to an additional input associated to the sulfuric acid used for the phosphoric acid production. Furthermore, results from SEM-EDX demonstrated that toxic elements are not distributed homogeneously into phosphogypsum. Most of these elements are concentrated in particles <20 microm of high porosity, and could be easily mobilized by leaching and/or erosion.

  8. Opaque rock fragments

    SciTech Connect

    Abhijit, B.; Molinaroli, E.; Olsen, J.

    1987-05-01

    The authors describe a new, rare, but petrogenetically significant variety of rock fragments from Holocene detrital sediments. Approximately 50% of the opaque heavy mineral concentrates from Holocene siliciclastic sands are polymineralic-Fe-Ti oxide particles, i.e., they are opaque rock fragments. About 40% to 70% of these rock fragments show intergrowth of hm + il, mt + il, and mt + hm +/- il. Modal analysis of 23,282 opaque particles in 117 polished thin sections of granitic and metamorphic parent rocks and their daughter sands from semi-arid and humid climates show the following relative abundances. The data show that opaque rock fragments are more common in sands from igneous source rocks and that hm + il fragments are more durable. They assume that equilibrium conditions existed in parent rocks during the growth of these paired minerals, and that the Ti/Fe ratio did not change during oxidation of mt to hm. Geothermometric determinations using electron probe microanalysis of opaque rock fragments in sand samples from Lake Erie and the Adriatic Sea suggest that these rock fragments may have equilibrated at approximately 900/sup 0/ and 525/sup 0/C, respectively.

  9. 8,9-Epoxyeicosatrienoic acid analog protects pulmonary artery smooth muscle cells from apoptosis via ROCK pathway

    SciTech Connect

    Ma, Jun; Zhang, Lei; Li, Shanshan; Liu, Shulin; Ma, Cui; Li, Weiyang; Falck, J.R.; Manthati, Vijay L.; Reddy, D. Sudarshan; Medhora, Meetha; Jacobs, Elizabeth R.; Zhu, Daling

    2010-08-15

    Epoxyeicosatrienoic acids (EETs), metabolites of arachidonic acid (AA) catalyzed by cytochrome P450 (CYP), have many essential biologic roles in the cardiovascular system including inhibition of apoptosis in cardiomyocytes. In the present study, we tested the potential of 8,9-EET and derivatives to protect pulmonary artery smooth muscle cells (PASMCs) from starvation induced apoptosis. We found 8,9-epoxy-eicos-11(Z)-enoic acid (8,9-EET analog (214)), but not 8,9-EET, increased cell viability, decreased activation of caspase-3 and caspase-9, and decreased TUNEL-positive cells or nuclear condensation induced by serum deprivation (SD) in PASMCs. These effects were reversed after blocking the Rho-kinase (ROCK) pathway with Y-27632 or HA-1077. Therefore, 8,9-EET analog (214) protects PASMC from serum deprivation-induced apoptosis, mediated at least in part via the ROCK pathway. Serum deprivation of PASMCs resulted in mitochondrial membrane depolarization, decreased expression of Bcl-2 and enhanced expression of Bax, all effects were reversed by 8,9-EET analog (214) in a ROCK dependent manner. Because 8,9-EET and not the 8,9-EET analog (214) protects pulmonary artery endothelial cells (PAECs), these observations suggest the potential to differentially promote apoptosis or survival with 8,9-EET or analogs in pulmonary arteries.

  10. 8,9-Epoxyeicosatrienoic acid analog protects pulmonary artery smooth muscle cells from apoptosis via ROCK pathway

    PubMed Central

    Ma, Jun; Zhang, Lei; Li, Shanshan; Liu, Shulin; Ma, Cui; Li, Weiyang; Falck, J.R.; Manthati, Vijay L.; Reddy, D. Sudarshan; Medhora, Meetha; Jacobs, Elizabeth R.; Zhu, Daling

    2010-01-01

    Epoxyeicosatrienoic acids (EETs), metabolites of arachidonic acid (AA) catalyzed by cytochrome P450 (CYP), have many essential biologic roles in the cardiovascular system including inhibition of apoptosis in cardiomyocytes. In the present study, we tested the potential of 8,9-EET and derivatives to protect pulmonary artery smooth muscle cells (PASMCs) from starvation induced apoptosis. We found 8,9-epoxy-eicos-11(Z)-enoic acid (8,9-EET analog(214)), but not 8,9-EET, increased cell viability, decreased activation of caspase-3 and caspase-9, and decreased TUNEL-positive cells or nuclear condensation induced by serum deprivation (SD) in PASMCs. These effects were reversed after blocking the Rho-kinase (ROCK) pathway with Y-27632 or HA-1077. Therefore, 8,9-EET analog(214) protects PASMC from serum deprivation-induced apoptosis, mediated at least in part via the ROCK pathway. Serum deprivation of PASMCs resulted in mitochondrial membrane depolarization, decreased expression of Bcl-2 and enhanced expression of Bax, all effects were reversed by 8,9-EET analog(214) in a ROCK dependent manner. Because 8,9-EET and not the 8,9-EET analog(214) protects pulmonary artery endothelial cells (PAECs), these observations suggest the potential to differentially promote apoptosis or survival with 8,9-EET or analogs in pulmonary arteries. PMID:20493836

  11. Attached and Unattached Bacterial Communities in a 120-Meter Corehole in an Acidic, Crystalline Rock Aquifer

    PubMed Central

    Lehman, R. Michael; Roberto, Francisco F.; Earley, Drummond; Bruhn, Debby F.; Brink, Susan E.; O'Connell, Sean P.; Delwiche, Mark E.; Colwell, Frederick S.

    2001-01-01

    The bacteria colonizing geologic core sections (attached) were contrasted with those found suspended in the groundwater (unattached) by examining the microbiology of 16 depth-paired core and groundwater samples using a suite of culture-independent and culture-dependent analyses. One hundred twenty-two meters was continuously cored from a buried chalcopyrite ore hosted in a biotite-quartz-monzonite porphyry at the Mineral Park Mine near Kingman, Ariz. Every fourth 1.5-m core was acquired using microbiologically defensible methods, and these core sections were aseptically processed for characterization of the attached bacteria. Groundwater samples containing unattached bacteria were collected from the uncased corehole at depth intervals corresponding to the individual cores using an inflatable straddle packer sampler. The groundwater was acidic (pH 2.8 to 5.0), with low levels of dissolved oxygen and high concentrations of sulfate and metals, including ferrous iron. Total numbers of attached cells were less than 105 cells g of core material−1 while unattached cells numbered about 105 cells ml of groundwater−1. Attached and unattached acidophilic heterotrophs were observed throughout the depth profile. In contrast, acidophilic chemolithotrophs were not found attached to the rock but were commonly observed in the groundwater. Attached communities were composed of low numbers (<40 CFU g−1) of neutrophilic heterotrophs that exhibited a high degree of morphologic diversity, while unattached communities contained higher numbers (ca. 103 CFU ml−1) of neutrophilic heterotrophs of limited diversity. Sulfate-reducing bacteria were restricted to the deepest samples of both core and groundwater. 16S ribosomal DNA sequence analysis of attached, acidophilic isolates indicated that organisms closely related to heterotrophic, acidophilic mesophiles such as Acidiphilium organovorum and, surprisingly, to the moderately thermophilic Alicyclobacillus acidocaldarius were present

  12. Manifestation of Preferential Flow and Nitrate Transport in Central European Soils on Acid Crystalline Rocks

    NASA Astrophysics Data System (ADS)

    Dolezal, F.; Cislerova, M.; Vogel, T.; Zavadil, J.; Vacek, J.; Kvitek, T.; Prazak, P.; Nechvatal, M.; Bayer, T.

    2006-12-01

    Large areas of Central Europe are occupied by highlands and peneplains of medium altitudes, built by acid crystalline rocks. The soils overlying them are typically of medium textures. They are neither markedly water- repellent nor greatly swelling and shrinking. These landscapes are characterized by high vulnerability of water bodies, both surface and subsurface. The existing methodologies of vulnerability assessment regard the heavier among these soils as little vulnerable to diffuse pollution, while in reality they may be virtually equally vulnerable, because of the short-circuiting effect of preferential flow and transport. Our experiment site was Valeèov (49° 38' 40" N, 14° 30' 25" E, 461 m a.s.l.) in the Bohemo-Moravian highland, with average annual precipitation 660 mm and average annual air temperature 7.2 ° C. The field trials, starting from 2001, were focused on growing potato under different conditions. Soil moisture content was measured by Theta- probe capacitance sensors, soil water suction by Watermark sensors and tensiometers. Nitrate leaching was monitored by soil solution sampling with ceramic suction cups and zero-tension lysimeters. The hydraulic conductivity of the soil was measured on small cores and by suction and pressure infiltrometers. The following preferential flow manifestations are analyzed and quantified: a) the spatial variability of soil moisture content and suction after rainstorms, b) the spatial and temporal variability of soil's hydraulic conductivity and its dependence on soil moisture content, c) the spatial variability of percolation volumes in parallel lysimeters, d) the variability of nitrate concentrations in the lysimeter leachate, e) the apparent absence of correlation between leachate volumes and leachate concentrations in lysimeters, f) the lower mean and higher variance of leachate concentrations in lysimeters, in comparison with those in suction cups.

  13. Geologic and mineralogic controls on acid and metal-rich rock drainage in an alpine watershed, Handcart Gulch, Colorado

    USGS Publications Warehouse

    Bove, Dana J.; Caine, Jonathan S.; Lowers, Heather

    2012-01-01

    The surface and subsurface geology, hydrothermal alteration, and mineralogy of the Handcart Gulch area was studied using map and drill core data as part of a multidisciplinary approach to understand the hydrology and affects of geology on acid-rock drainage in a mineralized alpine watershed. Handcart Gulch was the locus of intense hydrothermal alteration that affected an area of nearly 3 square kilometers. Hydrothermal alteration and accompanied weak mineralization are spatially and genetically associated with small dacite to low-silica rhyolite stocks and plugs emplaced about 37-36 Ma. Felsic lithologies are commonly altered to a quartz-sericite-pyrite mineral assemblage at the surface, but alteration is more variable in the subsurface, ranging from quartz-sericite-pyrite-dominant in upper core sections to a propylitic variant that is more typical in deeper drill core intervals. Late-stage, hydrothermal argillic alteration [kaolinite and(or) smectite] was superimposed over earlier-formed alteration assemblages in the felsic rocks. Smectite in this late stage assemblage is mostly neoformed resulting from dissolution of chlorite, plagioclase, and minor illite in more weakly altered rocks. Hydrothermally altered amphibolites are characterized by biotitic alteration of amphibole, and subsequent alteration of both primary and secondary biotite to chlorite. Whereas pyrite is present both as disseminations and in small veinlets in the felsic lithologies, it is mostly restricted to small veinlets in the amphibolites. Base-metal sulfides including molybdenite, chalcopyrite, sphalerite, and galena are present in minor to trace amounts in the altered rocks. However, geologic data in conjunction with water geochemical studies indicate that copper mineralization may be present in unknown abundance in two distinct areas. The altered rocks contain an average of 8 weight percent fine pyrite that is largely devoid of metals in the crystal structure, which can be a significant

  14. Geochemical characterization of acid mine drainage from a waste rock pile, Mine Doyon, Québec, Canada

    NASA Astrophysics Data System (ADS)

    Sracek, O.; Choquette, M.; Gélinas, P.; Lefebvre, R.; Nicholson, R. V.

    2004-03-01

    Water quality in the unsaturated and saturated zones of a waste rock pile containing sulphides was investigated. The main objectives of the project were (1) the evaluation of geochemical trends including the acid mine drainage (AMD)-buffering mechanism and the role of secondary minerals, and (2) the investigation of the use of stable isotopes for the interpretation of physical and geochemical processes in waste rock. Pore water in unsaturated zone was sampled from suction lysimeters and with piezometers in underlying saturated rocks. The investigation revealed strong temporal (dry period vs. recharge period), and spatial (slope vs. central region of pile) variability in the formation of acid mine drainage. The main secondary minerals observed were gypsum and jarosite. There was a higher concentration of gypsum in solid phase at Site TBT than at Site 6, suggesting that part of the gypsum formed at Site 6 in the early stage of AMD has been already dissolved. Formation of secondary minerals contributed to the formation of AMD by opening of foliation planes in waste rock, thus increasing the access of oxidants like O 2 and Fe 3+ to previously encapsulated pyrite. The behavior of several dissolved species such as Mg, Al, and Fe 2+ can be considered as conservative in the leachate. Stable isotopes, deuterium and 18O, indicated internal evaporation within the pile, and were used to trace recharge pulses from snowmelt. Isotope trends for 34S and 18O(SO 4) indicated a lack of sulfate reduction and zones of active oxidation of pyrite, respectively. Results of numerical modeling of pyrite oxidation and gas and water transport were consistent with geochemical and isotopic trends and confirmed zones of high evaporation rate within the rock pile close to the slope. The results indicate that physical and chemical processes within the pile are strongly coupled and cannot be considered separately when oxidation rates are high and influence gas transport as a result of heat

  15. Phosphate Stability in Diagenetic Fluids Constrains the Acidic Alteration Model for Lower Mt. Sharp Sedimentary Rocks in Gale Crater, Mars

    NASA Technical Reports Server (NTRS)

    Berger, J. A.; Schmidt, M. E.; Izawa, M. R. M.; Gellert, R.; Ming, D. W.; Rampe, E. B.; VanBommel, S. J.; McAdam, A. C.

    2016-01-01

    The Mars rover Curiosity has encountered silica-enriched bedrock (as strata and as veins and associated halos of alteration) in the largely basaltic Murray Fm. of Mt. Sharp in Gale Crater. Alpha Particle X-ray Spectrometer (APXS) investigations of the Murray Fm. revealed decreasing Mg, Ca, Mn, Fe, and Al, and higher S, as silica increased (Fig. 1). A positive correlation between SiO2 and TiO2 (up to 74.4 and 1.7 wt %, respectively) suggests that these two insoluble elements were retained while acidic fluids leached more soluble elements. Other evidence also supports a silica-retaining, acidic alteration model for the Murray Fm., including low trace element abundances consistent with leaching, and the presence of opaline silica and jarosite determined by CheMin. Phosphate stability is a key component of this model because PO4 3- is typically soluble in acidic water and is likely a mobile ion in diagenetic fluids (pH less than 5). However, the Murray rocks are not leached of P; they have variable P2O5 (Fig. 1) ranging from average Mars (0.9 wt%) up to the highest values in Gale Crater (2.5 wt%). Here we evaluate APXS measurements of Murray Fm. bedrock and veins with respect to phosphate stability in acidic fluids as a test of the acidic alteration model for the Lower Mt. Sharp rocks.

  16. Application of Potential Phosphate-Solubilizing Bacteria and Organic Acids on Phosphate Solubilization from Phosphate Rock in Aerobic Rice

    PubMed Central

    Jusop, Shamshuddin; Naher, Umme Aminun; Othman, Radziah; Razi, Mohd Ismail

    2013-01-01

    A study was conducted at Universiti Putra Malaysia to determine the effect of phosphate-solubilizing bacteria (PSB) and organic acids (oxalic & malic) on phosphate (P) solubilization from phosphate rock (PR) and growth of aerobic rice. Four rates of each organic acid (0, 10, 20, and 30 mM), and PSB strain (Bacillus sp.) were applied to aerobic rice. Total bacterial populations, amount of P solubilization, P uptake, soil pH, and root morphology were determined. The results of the study showed significantly high P solubilization in PSB with organic acid treatments. Among the two organic acids, oxalic acid was found more effective compared to malic acid. Application of oxalic acid at 20 mM along with PSB16 significantly increased soluble soil P (28.39 mg kg−1), plant P uptake (0.78 P pot−1), and plant biomass (33.26 mg). Addition of organic acids with PSB and PR had no influence on soil pH during the planting period. A higher bacterial population was found in rhizosphere (8.78 log10 cfu g−1) compared to the nonrhizosphere and endosphere regions. The application of organic acids along with PSB enhanced soluble P in the soil solution, improved root growth, and increased plant biomass of aerobic rice seedlings without affecting soil pH. PMID:24288473

  17. Classification of mafic clasts from mesosiderites: Implications for endogenous igneous processes

    SciTech Connect

    Rubin, A.E. ); Mittlefehldt, D.W. )

    1992-02-01

    The authors have analyzed thirteen igneous pebbles from the Vaca Muerta, EET87500, and Bondoc mesosiderites by electron microprobe and instrumental neutron activation and combined these data with literature data for forty-three analyzed mesosiderite clasts. They classify these well-characterized clasts into the following five principal groups: (1) Polygenic and monogenic cumulates (39%) are coarse-grained gabbros that are highly depleted in incompatible elements (relative to H chondrites); they formed at moderate depth either as residues of low-degree partial melting of pre-existing cumulate eucrites or as cumulates from parent melts similar to cumulate eucrites. (2) Polygenic basalts (30%) are finer-grained rocks with positive europium anomalies, La/Lu ratios < 1, and lower rare earth element abundances than basaltic eucrites. It seems likely that these rocks were formed near their parent body surface by remelting mixtures of major amounts of basaltic eucrites and lesser amounts of cumulate eucrites. (3) Quench-textured rocks comprise two compositional groups, (a) those which resemble basaltic eucrites (5%), and (b) those which resemble cumulate eucrites (2%). The quench-textured rocks are probably monogenic; they formed most likely when small-scale impacts at their parent body surface totally melted small amounts of basaltic or cumulate eucrite material. (4) Monogenic basalts (11%) resemble basaltic eucrites and formed by endogenous igneous processes on the mesosiderite parent body (MPB). (5) Ultramafic rocks are cumulates consisting mainly of large crystals of orthopyroxene (9%) or olivine (4%). Orthopyroxenite clasts closely resemble diogenites and were formed most likely by endogenous igneous processes.

  18. Igpet software for modeling igneous processes: examples of application using the open educational version

    NASA Astrophysics Data System (ADS)

    Carr, Michael J.; Gazel, Esteban

    2016-09-01

    We provide here an open version of Igpet software, called t-Igpet to emphasize its application for teaching and research in forward modeling of igneous geochemistry. There are three programs, a norm utility, a petrologic mixing program using least squares and Igpet, a graphics program that includes many forms of numerical modeling. Igpet is a multifaceted tool that provides the following basic capabilities: igneous rock identification using the IUGS (International Union of Geological Sciences) classification and several supplementary diagrams; tectonic discrimination diagrams; pseudo-quaternary projections; least squares fitting of lines, polynomials and hyperbolae; magma mixing using two endmembers, histograms, x-y plots, ternary plots and spider-diagrams. The advanced capabilities of Igpet are multi-element mixing and magma evolution modeling. Mixing models are particularly useful for understanding the isotopic variations in rock suites that evolved by mixing different sources. The important melting models include, batch melting, fractional melting and aggregated fractional melting. Crystallization models include equilibrium and fractional crystallization and AFC (assimilation and fractional crystallization). Theses, reports and proposals concerning igneous petrology are improved by numerical modeling. For reviewed publications some elements of modeling are practically a requirement. Our intention in providing this software is to facilitate improved communication and lower entry barriers to research, especially for students.

  19. Rock specific hydraulic fracturing and matrix acidizing to enhance a geothermal system — Concepts and field results

    NASA Astrophysics Data System (ADS)

    Zimmermann, Günter; Blöcher, Guido; Reinicke, Andreas; Brandt, Wulf

    2011-04-01

    Enhanced geothermal systems (EGS) are engineered reservoirs developed to extract economic amounts of heat from low permeability and/or porosity geothermal resources. To enhance the productivity of reservoirs, a site specific concept is necessary to actively make reservoir conditions profitable using specially adjusted stimulation treatments, such as multi fracture concepts and site specific well path design. The results of previously performed stimulation treatments in the geothermal research well GtGrSk4/05 at Groß Schönebeck, Germany are presented. The reservoir is located at a 4100-4300 m depth within the Lower Permian of the NE German Basin with a bottom-hole temperature of 150 °C. The reservoir rock is classified by two lithological units from bottom to top: volcanic rocks (andesitic rocks) and siliciclastics ranging from conglomerates to fine-grained sandstones (fluvial sediments). The stimulation treatments included multiple hydraulic stimulations and an acid treatment. In order to initiate a cross-flow from the sandstone layer, the hydraulic stimulations were performed in different depth sections (two in the sandstone section and one in the underlying volcanic section). In low permeability volcanic rocks, a cyclic hydraulic fracturing treatment was performed over 6 days in conjunction with adding quartz in low concentrations to maintain a sustainable fracture performance. Flow rates of up to 150 l/s were realized, and a total of 13,170 m 3 of water was injected. A hydraulic connection to the sandstone layer was successfully achieved in this way. However, monitoring of the water level in the offsetting well EGrSk3/90, which is 475 m apart at the final depth, showed a very rapid water level increase due to the stimulation treatment. This can be explained by a connected fault zone within the volcanic rocks. Two gel-proppant treatments were performed in the slightly higher permeability sandstones to obtain long-term access to the reservoir rocks. During each

  20. The growth of large mafic intrusions: Comparing Niquelândia and Ivrea igneous complexes

    NASA Astrophysics Data System (ADS)

    Correia, Ciro Teixeira; Sinigoi, Silvano; Girardi, Vicente Antonio Vitorio; Mazzucchelli, Maurizio; Tassinari, Colombo Celso Gaeta; Giovanardi, Tommaso

    2012-12-01

    The Niquelândia Complex, Brazil, is one of the world's largest mafic-ultramafic plutonic complexes. Like the Mafic Complex of the Ivrea-Verbano Zone, it is affected by a pervasive high-T foliation and shows hypersolidus deformation structures, contains significant inclusions of country-rock paragneiss, and is subdivided into a Lower and an Upper Complex. In this paper, we present new SHRIMP U-Pb zircon ages that provide compelling evidence that the Upper and the Lower Niquelândia Complexes formed during the same igneous event at ca. 790 Ma. Coexistence of syn-magmatic and high-T subsolidus deformation structures indicates that both complexes grew incrementally as large crystal mush bodies which were continuously stretched while fed by pulses of fresh magma. Syn-magmatic recrystallization during this deformation resulted in textures and structures which, although appearing metamorphic, are not ascribable to post-magmatic metamorphic event(s), but are instead characteristic of the growth process in huge and deep mafic intrusions such as both the Niquelândia and Ivrea Complexes. Melting of incorporated country-rock paragneiss continued producing hybrid rocks during the last, vanishing stages of magmatic crystallization. This resulted in the formation of minor, late-stage hybrid rocks, whose presence obscures the record of the main processes of interaction between mantle magmas and crustal components, which may be active at the peak of the igneous events and lead to the generation of eruptible hybrid magmas.

  1. Magma storage of an alkali ultramafic igneous suite from Chamberlindalen, SW Svalbard

    NASA Astrophysics Data System (ADS)

    Gołuchowska, Karolina; Barker, Abigail K.; Czerny, Jerzy; Majka, Jarosław; Manecki, Maciej; Farajewicz, Milena; Dwornik, Maciej

    2016-10-01

    An alkali mafic-ultramafic igneous suite of composite intrusions, lenses and associated greenstones are hosted by Neoproterozoic metasedimentary sequences in Chamberlindalen, Southwest Svalbard. This study focuses on the alkali igneous suite of Chamberlindalen with a view to determining the conditions of magma storage. The rocks from Chamberlindalen display cumulate textures, are highly magnesian and are classified as alkaline by the occurrence of kaersutite. They have textures that indicate cocrystallization of primary magmatic minerals such as diopside, kaersutite-ferrokaersutite and biotite-phlogopite in different proportions. The historic magma plumbing system for the alkaline cumulates has been reconstructed by thermobarometry. Diopside and kaersutite crystallization in the alkaline cumulates show a dominant level of magma storage between 30 and 50 km in the subcontinental lithospheric mantle.

  2. Climate Change and Water Quality in the Rocky Mountains: challenges of too much summer for addressing acid rock drainage (Invited)

    NASA Astrophysics Data System (ADS)

    McKnight, D. M.; Crouch, C. M.; Rue, G. P.

    2013-12-01

    A major water quality concern in the Rocky Mountains is acid rock drainage, which causes acidic conditions and high metal concentrations. The 30-year water quality record for the Snake River watershed in Colorado, USA, shows that for the summer low-flow period zinc concentrations have increased four- to six-fold concurrently with a two- to three week advancement in spring snowmelt. We found that the main source of acidity, zinc and other metals, including rare earth elements to the upper Snake River was a tributary draining an alpine area rich in disseminated pyrite. By conducting a tracer experiment in this tributary, we demonstrated that more than half of the trace metal and acidity loading entered in an upper steep, rocky reach where the tributary is fed by an alpine spring. Another increase in flow and metal loading occurred where the tributary flows through a gently-sloped wetland area containing a bog iron deposit. Analysis of the tracer experiment indicated a significant increase in hyporheic exchange along this wetland reach, where decreases in pH of the water exchanging in the hyporheic zone may be mobilizing metals that had been sequestered in the wetland through sorption to iron oxides. One possible scenario is that decreasing pH in the upper reach has reached a threshold, resulting in mobilization of metals from the hyporheic zone of the wetland. This study illustrates how changes in hydrologic regime may cause changes in biogeochemical processes that exacerbate the danger to aquatic ecosystems associated with acid rock drainage.

  3. Agronomic effectiveness of biofertilizers with phosphate rock, sulphur and Acidithiobacillus for yam bean grown on a Brazilian tableland acidic soil.

    PubMed

    Stamford, N P; Santos, P R; Santos, C E S; Freitas, A D S; Dias, S H L; Lira, M A

    2007-04-01

    Phosphate rocks have low available P and soluble P fertilizers have been preferably used in plant crop production, although economic and effective P sources are needed. Experiments were carried out on a Brazilian Typic Fragiudult soil with low available P to evaluate the agronomic effectiveness of phosphate rock (PR) compared with soluble phosphate fertilizer. Yam bean (Pachyrhizus erosus) inoculated with rhizobia (strains NFB 747 and NFB 748) or not inoculated was the test crop. Biofertilizers were produced in field furrows by mixing phosphate rock (PR) and sulphur inoculated with Acidithiobacillus (S+Ac) in different rates (50, 100, 150 and 200 g S kg(-1) PR), with 60 days of incubation. Treatments were carried out with PR; biofertilizers B(50), B(100), B(150), B(200); triple super phosphate (TSP); B(200) without Acidithiobacillus and a control treatment without P application (P(0)). TSP and biofertilizers plus S inoculated with Acidithiobacillus increased plant growth. Soil acidity and available P increased when biofertilizers B(150) and B(200) were applied. We conclude that biofertilizers may be used as P source; however, long term use will reduce soil pH and potentially reduce crop growth.

  4. Solution of rocks and refractory minerals by acids at high temperatures and pressures. Determination of silica after decomposition with hydrofluoric acid

    USGS Publications Warehouse

    May, I.; Rowe, J.J.

    1965-01-01

    A modified Morey bomb was designed which contains a removable nichromecased 3.5-ml platinium crucible. This bomb is particularly useful for decompositions of refractory samples for micro- and semimicro-analysis. Temperatures of 400-450?? and pressures estimated as great as 6000 p.s.i. were maintained in the bomb for periods as long as 24 h. Complete decompositions of rocks, garnet, beryl, chrysoberyl, phenacite, sapphirine, and kyanite were obtained with hydrofluoric acid or a mixture of hydrofluoric and sulfuric acids; the decomposition of chrome refractory was made with hydrochloric acid. Aluminum-rich samples formed difficultly soluble aluminum fluoride precipitates. Because no volatilization losses occur, silica can be determined on sample solutions by a molybdenum-blue procedure using aluminum(III) to complex interfering fluoride. ?? 1965.

  5. Tectonomagmatic origin of Precambrian rocks of Mexico and Argentina inferred from multi-dimensional discriminant-function based discrimination diagrams

    NASA Astrophysics Data System (ADS)

    Pandarinath, Kailasa

    2014-12-01

    Several new multi-dimensional tectonomagmatic discrimination diagrams employing log-ratio variables of chemical elements and probability based procedure have been developed during the last 10 years for basic-ultrabasic, intermediate and acid igneous rocks. There are numerous studies on extensive evaluations of these newly developed diagrams which have indicated their successful application to know the original tectonic setting of younger and older as well as sea-water and hydrothermally altered volcanic rocks. In the present study, these diagrams were applied to Precambrian rocks of Mexico (southern and north-eastern) and Argentina. The study indicated the original tectonic setting of Precambrian rocks from the Oaxaca Complex of southern Mexico as follows: (1) dominant rift (within-plate) setting for rocks of 1117-988 Ma age; (2) dominant rift and less-dominant arc setting for rocks of 1157-1130 Ma age; and (3) a combined tectonic setting of collision and rift for Etla Granitoid Pluton (917 Ma age). The diagrams have indicated the original tectonic setting of the Precambrian rocks from the north-eastern Mexico as: (1) a dominant arc tectonic setting for the rocks of 988 Ma age; and (2) an arc and collision setting for the rocks of 1200-1157 Ma age. Similarly, the diagrams have indicated the dominant original tectonic setting for the Precambrian rocks from Argentina as: (1) with-in plate (continental rift-ocean island) and continental rift (CR) setting for the rocks of 800 Ma and 845 Ma age, respectively; and (2) an arc setting for the rocks of 1174-1169 Ma and of 1212-1188 Ma age. The inferred tectonic setting for these Precambrian rocks are, in general, in accordance to the tectonic setting reported in the literature, though there are some inconsistence inference of tectonic settings by some of the diagrams. The present study confirms the importance of these newly developed discriminant-function based diagrams in inferring the original tectonic setting of

  6. Stabile Chlorine Isotope Study of Martian Shergottites and Nakhlites; Whole Rock and Acid Leachates and Residues

    NASA Technical Reports Server (NTRS)

    Nakamura, N.; Nyquist, L. E.; Reese, Y.; Shih, C-Y; Fujitani, T.; Okano, O.

    2011-01-01

    We have established a precise analytical technique for stable chlorine isotope measurements of tiny planetary materials by TIMS (Thermal Ionization Mass Spectrometry) [1], for which the results are basically consistent with the IRMS tech-nique (gas source mass spectrometry) [2,3,4]. We present here results for Martian shergottites and nakhlites; whole rocks, HNO3-leachates and residues, and discuss the chlorine isotope evolution of planetary Mars.

  7. Polymerization on the rocks: negatively-charged alpha-amino acids

    NASA Technical Reports Server (NTRS)

    Hill, A. R. Jr; Bohler, C.; Orgel, L. E.; Bada, J. L. (Principal Investigator)

    1998-01-01

    Oligomers of the negatively-charged amino acids, glutamic acid, aspartic acid, and O-phospho-L-serine are adsorbed by hydroxylapatite and illite with affinities that increase with oligomer length. In the case of oligo-glutamic acids adsorbed on hydroxylapatite, addition of an extra residue results in an approximately four-fold increase in the strength of adsorption. Oligomers much longer than the 7-mer are retained tenaciously by the mineral. Repeated incubation of short oligo-glutamic acids adsorbed on hydroxylapatite or illite with activated monomer leads to the accumulation of oligomers at least 45 units long. The corresponding reactions of aspartic acid and O-phospho-L-serine on hydroxylapatite are less effective in generating long oligomers, while illite fails to accumulate substantial amounts of long oligomers of aspartic acid or of O-phospho-L-serine.

  8. Polymerization on the rocks: negatively-charged alpha-amino acids.

    PubMed

    Hill, A R; Böhler, C; Orgel, L E

    1998-06-01

    Oligomers of the negatively-charged amino acids, glutamic acid, aspartic acid, and O-phospho-L-serine are adsorbed by hydroxylapatite and illite with affinities that increase with oligomer length. In the case of oligo-glutamic acids adsorbed on hydroxylapatite, addition of an extra residue results in an approximately four-fold increase in the strength of adsorption. Oligomers much longer than the 7-mer are retained tenaciously by the mineral. Repeated incubation of short oligo-glutamic acids adsorbed on hydroxylapatite or illite with activated monomer leads to the accumulation of oligomers at least 45 units long. The corresponding reactions of aspartic acid and O-phospho-L-serine on hydroxylapatite are less effective in generating long oligomers, while illite fails to accumulate substantial amounts of long oligomers of aspartic acid or of O-phospho-L-serine.

  9. Shallow drilling investigation of contact relationships in the Wichita Mountains igneous province

    SciTech Connect

    Gilbert, M.C.; Hogan, J.P. . School of Geology and Geophysics); Luza, K. )

    1993-02-01

    Within the Wichita Mountains Igneous Province, a variety of mineralogically, texturally and compositionally diverse hybrid rock types (i.e. gabbro-diorites, monzonites and granodiorites) crop out at gabbro-grants contacts. Possible coeval sedimentary rocks associated with crustal rifting are restricted to a few scattered, isolated exposures of a mineralogically variable group of meta-quartzites (Meers Quartzite). Typically these outcrops of meta-quartzite are of limited areal extent and are surrounded by either gabbro, granite, rhyolite or a combination of these rock types. However, the origin of both the hybrid rock types and the Meers Quartzite remains enigmatic because outcrops containing complete and clear contact relationships are extremely rare. At present, direct testing of models is difficult as complete exposure of contacts between these units is extremely rare due to deposition of younger sedimentary units and severe degradation by weathering. Poor condition of existing samples has hampered geochemical and other petrologic methods in evaluating models. Four potential drilling sites have been selected where critical contacts between major geologic units are interpreted to be present in the shallow subsurface (<300 ft.). Objectives of drilling are (1) direct observation of contacts between rock units by retrieval of a complete core sample from the drill hole, (2) retrieval of freshest possible rock material for petrographic and geochemical analysis and (3) retrieval of a complete transect beginning in Mount Scott Granite or Meers Quartzite across the hybrid rock zone and into the substrate gabbro to document variations associated with the transition.

  10. Procedures for Identifying Rocks with Similar Features.

    ERIC Educational Resources Information Center

    Powell, William E.

    1984-01-01

    The purpose of this article is to provide college level physical geography and geology teachers with practical and simple techniques to help students classify and understand igneous, sedimentary, and metamorphic rocks. Essential equipment is also discussed, and recommended readings are listed. (RM)

  11. Rocks Are Boring--Aren't They?

    ERIC Educational Resources Information Center

    Lievesley, Tara

    2014-01-01

    The new English Curriculum requiring not only the study of sedimentary and igneous rocks but also understanding of fossil formation, is a great opportunity to make this one of the most exciting units any science teacher can present. When an animal or plant dies, it "disappears" completely as it is degraded by a range of organisms. It may…

  12. 40Ar/39Ar hornblende and biotite geochronology of the Bulfat Igneous Complex, Zagros Suture Zone, NE Iraq: New insights on complexities of Paleogene arc magmatism during closure of the Neotethys Ocean

    NASA Astrophysics Data System (ADS)

    Aswad, Khalid J.; Ali, Sarmad A.; Al. Sheraefy, Ruaa M.; Nutman, Allen P.; Buckman, Solomon; Jones, Brian G.; Jourdan, F.

    2016-12-01

    In NE Iraq, the eastern edge of the Arabian plate is overlain by arc rock allochthons whose genesis and tectonic emplacement were related to the consumption and closure of the Neotethys Ocean. This paper demonstrates the occurrence of unrelated Paleogene arc rocks in two adjacent allochthons. The Bulfat Igneous Complex at Wadi Rashid (NE Iraq) is an intrusion within the Upper Allochthon Albian-Cenomanian Gimo-Qandil sequence suprasubduction zone assemblage. A thrust separates this allochthon from the underlying Lower Allochthon of the Eocene-Oligocene Walash-Naopurdan volcanic-sedimentary arc rocks. The Bulfat Igneous Complex at Wadi Rashid consists of gabbro and granitic composite intrusions in which components mingle down to a small scale. Textural relationships in the Bulfat Igneous Complex rocks indicate emplacement at high crustal levels with rapid cooling, which is consistent with amphibole geobarometry indicating crystallisation pressures between 250 and 300 Mpa. Ti-rich igneous pargasite and Ti-rich igneous Fe-biotite from gabbroic and granitic components yielded 40Ar/39Ar ages of 39.23 ± 0.21 and 38.87 ± 0.24 Ma respectively. These ages agree within analytical error and suggest coeval emplacement and rapid cooling of mafic and felsic magmas in the Eocene, in an event that was distinct and much younger than the host Albian-Cenomanian rocks. This igneous event was unrelated to formation of Cenozoic rocks in the underlying, tectonically separate, lower allochthon. The trace element signatures of the Wadi Rashi volcanic rocks show volcanic-arc characteristics for the granites and the gabbroic rocks resemble E type MORB. The presence of Eocene arc-related rocks in two allochthons suggests complexity in Paleogene subduction systems, with possibly two subduction zones operating at that time.

  13. Assessing the volcanic styles of the North Atlantic Igneous Province and their potential implications for the PETM

    NASA Astrophysics Data System (ADS)

    Jerram, Dougal; Reynolds, Peter; Jones, Morgan; Svensen, Henrik; Planke, Sverre; Millett, John; Galland, Olivier; Angkasa, Syahreza; Schofield, Nick; Howell, John

    2016-04-01

    In order to understand the role that large igneous provinces play in changing climatic conditions, it is important to constrain the different styles of volcanism and their volumes, both temporally and spatially. Regional variations in palaeo-environment as well as different volcanic materials (basic-acidic) can all have effects on the eruption styles, and determine whether eruptions effectively release gases into the atmosphere and hydrosphere. The North Atlantic Igneous Province (NAIP) covers a vast area as well as a significant time span, having formed at 60-55 Ma. Importantly, its' formation is implicated in the climatic perturbations at the Palaeocene-Eocene Thermal Maximum (PETM). The products of volcanism in the NAIP range from lava flows and hyaloclastites to more explosive tephra forming eruptions from both basaltic and more evolved eruptions. The explosive end member styles of both mafic and felsic volcanism also produce ash beds in the rock record at key times. Hydrothermal vent structures which are predominantly related with the emplacement of large (>1000 km3) intrusions into the subvolcanic basins in the NAIP are another style of eruption, where climate-forcing gases can be transferred into the atmosphere and hydrosphere. In this case, the types and volumes of gas produced by intrusions is heavily dependent on the host-rock sediment properties that they intrude through. The distribution of vent structures can be shown to be widespread on both the Norwegian and the Greenland margins of the NAIP. In this overview we assess the main eruption styles, deposits and their distribution within the NAIP using mapped examples from offshore seismic data as well as outcrop analogues, highlighting the variability of these structures and their deposits. As the availability of 3D data from offshore and onshore increases, the full nature of the volcanic stratigraphy from the subvolcanic intrusive complexes, through the main eruption cycles into the piercing vent

  14. Acid-fog deposition at Kilauea volcano: A possible mechanism for the formation of siliceous-sulfate rock coatings on Mars

    NASA Astrophysics Data System (ADS)

    Schiffman, Peter; Zierenberg, Robert; Marks, Naomi; Bishop, Janice L.; Darby Dyar, M.

    2006-11-01

    On the summit of Kilauea volcano, sulfur dioxide, which is continuously emitted from Halemaumau crater and rapidly sequestered into sulfuric-acid rich aerosol entrained in the prevailing trade winds, is subsequently precipitated as acid fog immediately downwind from Kilauea caldera in the Kau Desert. The characteristic pH of surface tephra deposits is <4.0 in Sand Wash, a region of nearly continuous, acidic aerosol fallout immediately southwest of the caldera. Vertical exposures of unconsolidated tephras of the Keanakakoi Ash found within fissures and small, dry gullies are coated with thin rock coatings of amorphous silica and jarosite. These rock coatings are formed via an evaporative mechanism whereby acidic pore fluids, circulating in the upper few meters within the highly porous tephra, are wicked toward the walls of the gullies. Geochemical modeling of the rock coating formation process implies that the sulfate formation via evaporation occurs subsequent to minimal interaction of acidic pore fluids with the basaltic tephra. This also suggests that the cycle from acid-fog fallout to precipitation of the siliceous-sulfate rock coatings must occur quite rapidly. Acid-fog deposition of sulfate and silica at Kilauea may provide one mechanism for the origin of jarosite-bearing outcrops on Mars.

  15. Relationship of pegmatites to U-Th mineralization in Precambrian crystalline rocks near Easton, Pennsylvania

    SciTech Connect

    Brand, C.C.; Malinconico, L.L. Jr. . Dept. of Geology); Tepper, J.H. . Dept. of Geology)

    1993-03-01

    Previous studies have shown that high radon levels in the Easton area are not simply confined to the igneous crystalline rocks of the Reading Prong. Since the radon is the result of the decay of uranium/thorium bearing minerals, the question then is where are these minerals hosted. Two hypotheses have been proposed for the origin of this mineralization: (1) derivation from an acidic magma during a hydrothermal stage of pegmatite intrusion, or (2) synsedimentary deposition in reducing, oceanic waters with subsequent crystallization of uraninite during metamorphism. The goal of the present study is to determine which process(es) were responsible for the mineralization and to determine where the uranium and thorium are hosted in the Precambrian rocks in the Easton area. Gamma surveys at three locations have demonstrated high radioactivity levels associated with the pegmatites (8,000--750,000 C/min.). Despite the fact that the host rocks and surrounding Paleozoic carbonates have been shown to have high levels of radon, the authors have measured significantly lower radioactivity levels (3,000--8,000 C/min.) in these rocks. The radioactivity levels tend to be high a very short distance into the host and then decrease very rapidly away from the pegmatites. The migmatitic regions in the Byram gneiss (20,000--60,000 C/min.) are considerably higher than the rest of the gneiss (8,000--12,000 C/min.) suggesting remobilization of U-Th during partial melting. These data tend to support the hypothesis that most of the radon is derived from the decay of elements concentrated in the igneous rocks, which subsequently migrated into the host rocks.

  16. Synmagmatic deformation in the underplated igneous complex of the Ivrea-Verbano zone

    USGS Publications Warehouse

    Quick, J.E.; Sinigoi, S.; Negrini, L.; Demarchi, G.; Mayer, A.

    1992-01-01

    The Ivrea-Verbano zone, northern Italy, contains an igneous complex up to 10km thick that is thought to have been intruded near the interface between the continental crust and mantle during the late Paleozoic. New data indicate that this complex is pervasively deformed and concentrically foliated. The presence of analogous features in ophiolitic gabbros suggests that emplacement of the Ivrea-Verbano zone plutonic rocks involved large-scale flow of crystal mush in a dynamic, and possibly extensional, tectonic environment. -from Authors

  17. Lipid, fatty acid and protein content of late larval to early juvenile stages of the western rock lobster, Panulirus cygnus.

    PubMed

    Limbourn, Andrew J; Nichols, Peter D

    2009-03-01

    Lipid, fatty acid and protein content were determined individually on 7 phyllosomata, 69 clear pueruli, 286 pre-moult pueruli, and 86 juvenile western rock lobster (WRL) collected from four locations between the settlement seasons 2000 to 2006 to evaluate compositional changes during the non-feeding puerulus stage. Only the lipid content, particularly the phospholipids, decreased significantly with development. Protein declined sharply following moult to the juvenile. PL comprised between 86-94% of total lipid in all animals, and declined most between phyllosomata and clear pueruli (238.5 to 121.4 mg g(-1) DW) (p<0.001). Triacylglycerols were the only lipid to increase in absolute amounts with development, but declined 53% on average following moult to juvenile. This increase in TAG is likely due to the conversion of phospholipids to triacylglycerols. Monounsaturated fatty acids were the main energy form utilised during benthic development while polyunsaturated fatty acids showed a high degree of sparing. The n-3:n-6 fatty acid ratio of juveniles indicates that they may be approaching critically low levels of stored lipid energy reserves. Both protein, and lipid, declined sharply from the final puerulus phase to the juvenile confirming that a high energetic demand is required to fuel the moulting process.

  18. Experimental Acid Weathering of Fe-Bearing Mars Analog Minerals and Rocks: Implications for Aqueous Origin of Hematite-Bearing Sediments in Meridiani Planum, Mars

    NASA Technical Reports Server (NTRS)

    Golden, D. C.; Koster, A. M.; Ming, D. W.; Morris, R. V.; Mertzman, S. A.

    2011-01-01

    A working hypothesis for Meridiani evaporite formation involves the evaporation of fluids derived from acid weathering of Martian basalts and subsequent diagenesis [1, 2]. However, there are no reported experimental studies for the formation of jarosite and gray hematite (spherules), which are characteristic of Meridiani rocks from Mars analog precursor minerals. A terrestrial analog for hematite spherule formation from basaltic rocks under acidic hydrothermal conditions has been reported [3], and we have previously shown that the hematite spherules and jarosite can be synthetically produced in the laboratory using Fe3+ -bearing sulfate brines under hydrothermal conditions [4]. Here we expand and extend these studies by reacting Mars analog minerals with sulfuric acid to form Meridiani-like rock-mineral compositions. The objective of this study is to provide environmental constraints on past aqueous weathering of basaltic materials on Mars.

  19. Origin of saline, neutral-pH, reduced epithermal waters by reaction of acidic magmatic gas condensates with wall rock

    SciTech Connect

    Reed, M.H. . Dept. of Geological Sciences)

    1993-04-01

    Fluid inclusions in quartz and sphalerite of epithermal veins containing galena, sphalerite and chalcopyrite with silver sulfides and electrum commonly have salinities of 2 to 10 weight percent NaCl equivalent. Examples include Bohemia, OR, Comstock, NV, and Creede, CO. Salinities in such base metal-rich systems are apparently greater than those in gold-adularia, base metal-poor systems such as Sleeper, NV, Republic, WA, and Hishikare, Kyushu. Saline epithermal fluids are commonly assumed to have been derived from saline magmatic brines, from local host formations, as has been suggested for Creede, or from evaporative concentration (boiling) of more dilute meteoric ground water. Another possibility, which may be the most common origin, is reaction of wall rocks with magmatic gas condensates rich in HCl and sulfuric acid. A mixture of one part Augustine Volcanic gas condensate in 10 parts cold ground water has a pH of 0.7 and the dominant cation is H[sup +] by a factor of 10[sup 4]. Calculated reaction of this condensate mixture with andesite at 300 C to a water/rock ratio (w/r) of 4.6 yields an NaCl-dominated fluid with a total salinity of 2.1 wt %. and pH 3.7. Further reaction, to w/r 0.14 yields a fluid salinity of 2.6 wt % and pH of 5.7; this fluid is in equilibrium with a propylitic alteration assemblage. Aqueous sulfide accumulates during the rock reaction as sulfate is reduced to sulfide when ferrous iron is oxidized to ferric iron. Sulfide concentration in the latter fluid is 32 ppm, far exceeding sulfate concentration. In the overall reaction, hydrogen ion is exchanged for base cations (including base metals) and sulfate is reduced to sulfide.

  20. Geology is the Key to Explain Igneous Activity in the Mediterranean Area

    NASA Astrophysics Data System (ADS)

    Lustrino, M.

    2014-12-01

    Igneous activity in tectonically complex areas can be interpreted in many different ways, producing completely different petrogenetic models. Processes such as oceanic and continental subduction, lithospheric delamination, changes in subduction polarity, slab break-off and mantle plumes have all been advocated as causes for changes in plate boundaries and magma production, including rate and temporal distribution, in the circum-Mediterranean area. This region thus provides a natural laboratory to investigate a range of geodynamic and magmatic processes. Although many petrologic and tectonic models have been proposed, a number of highly controversial questions still remain. No consensus has yet been reached about the capacity of plate-tectonic processes to explain the origin and style of the magmatism. Similarly, there is still not consensus on the ability of geochemical and petrological arguments to reveal the geodynamic evolution of the area. The wide range of chemical and mineralogical magma compositions produced within and around the Mediterranean, from carbonatites to strongly silica-undersaturated silico-carbonatites and melilitites to strongly silica-oversaturated rhyolites, complicate models and usually require a large number of unconstrained assumptions. Can the calcalkaline-sodic alkaline transition be related to any common petrogenetic point? Is igneous activity plate-tectonic- (top-down) or deep-mantle-controlled (bottom-up)? Do the rare carbonatites and carbonate-rich igneous rocks derive from the deep mantle or a normal, CO2-bearing upper mantle? Do ultrapotassic compositions require continental subduction? Understanding chemically complex magmas emplaced in tectonically complex areas require open minds, and avoiding dogma and assumptions. Studying the geology and shallow dynamics, not speculating about the deep lower mantle, is the key to understanding the igneous activity.

  1. Large igneous provinces linked to supercontinent assembly

    NASA Astrophysics Data System (ADS)

    Wang, Yu; Santosh, M.; Luo, Zhaohua; Hao, Jinhua

    2015-04-01

    Models for the disruption of supercontinents have considered mantle plumes as potential triggers for continental extension and the formation of large igneous provinces (LIPs). An alternative hypothesis of top-down tectonics links large volcanic eruptions to lithospheric delamination. Here we argue that the formation of several LIPs in Tarim, Yangtze, Lhasa and other terranes on the Eurasian continent was coeval with the assembly of the Pangean supercontinent, in the absence of plumes rising up from the mantle transition zone or super-plumes from the core-mantle boundary. The formation of these LIPs was accompanied by subduction and convergence of continents and micro-continents, with no obvious relation to major continental rifting or mantle plume activity. Our model correlates LIPs with lithospheric extension caused by asthenospheric flow triggered by multiple convergent systems associated with supercontinent formation.

  2. From Rocks to Cement. What We Make. Science and Technology Education in Philippine Society.

    ERIC Educational Resources Information Center

    Philippines Univ., Quezon City. Science Education Center.

    This module deals with the materials used in making concrete hollow blocks. Topics discussed include: (1) igneous, metamorphic, and sedimentary rocks; (2) weathering (the process of breaking down rocks) and its effects on rocks; (3) cement; (4) stages in the manufacturing of Portland cement; and (5) the transformation of cement into concrete…

  3. Number of Waste Package Hit by Igneous Intrusion

    SciTech Connect

    M. Wallace

    2004-10-13

    The purpose of this scientific analysis report is to document calculations of the number of waste packages that could be damaged in a potential future igneous event through a repository at Yucca Mountain. The analyses include disruption from an intrusive igneous event and from an extrusive volcanic event. This analysis supports the evaluation of the potential consequences of future igneous activity as part of the total system performance assessment for the license application (TSPA-LA) for the Yucca Mountain Project (YMP). Igneous activity is a disruptive event that is included in the TSPA-LA analyses. Two igneous activity scenarios are considered: (1) The igneous intrusion groundwater release scenario (also called the igneous intrusion scenario) considers the in situ damage to waste packages or failure of waste packages that occurs if they are engulfed or otherwise affected by magma as a result of an igneous intrusion. (2) The volcanic eruption scenario depicts the direct release of radioactive waste due to an intrusion that intersects the repository followed by a volcanic eruption at the surface. An igneous intrusion is defined as the ascent of a basaltic dike or dike system (i.e., a set or swarm of multiple dikes comprising a single intrusive event) to repository level, where it intersects drifts. Magma that does reach the surface from igneous activity is an eruption (or extrusive activity) (Jackson 1997 [DIRS 109119], pp. 224, 333). The objective of this analysis is to develop a probabilistic measure of the number of waste packages that could be affected by each of the two scenarios.

  4. Anti-cancer effect of ursolic acid activates apoptosis through ROCK/PTEN mediated mitochondrial translocation of cofilin-1 in prostate cancer

    PubMed Central

    Gai, Wen-Tao; Yu, Da-Peng; Wang, Xin-Sheng; Wang, Pei-Tao

    2016-01-01

    Ursolic acid is a type of pentacyclic triterpene compound with multiple pharmacological activities including cancer resistance, protection from liver injury, antisepsis, anti-inflammation and antiviral activity. The present study aimed to investigate the anticancer effect of ursolic acid. Ursolic acid activates cell apoptosis and its pro-apoptotic mechanism remains to be fully elucidated. Cell Counting kit-8 assays, flow cytometric analysis and analysis of caspase-3 and caspase-9 activity were used to estimate the anticancer effect of ursolic acid on DU145 prostate cancer cells. The protein expression of cytochrome c, rho-associated protein kinase (ROCK), phosphatase and tensin homolog (PTEN) and cofilin-1 were examined using western blot analysis. In the present study, ursolic acid significantly suppressed cell growth and induced apoptosis, as well as increasing caspase-3 and caspase-9 activities of DU145 cells. Furthermore, cytoplasmic and mitochondrial cytochrome c protein expression was significantly activated and suppressed, respectively, by ursolic acid. Ursolic acid significantly suppressed the ROCK/PTEN signaling pathway and inhibited cofilin-1 protein expression in DU145 cells. The results of the present study indicate that the anticancer effect of ursolic acid activates cell apoptosis through ROCK/PTEN mediated mitochondrial translocation of cofilin-1 in prostate cancer. PMID:27698874

  5. Comparison of hot hydroxylamine hydrochloride and oxalic acid leaching of stream sediment and coated rock samples as anomaly enhancement techniques

    USGS Publications Warehouse

    Filipek, L.H.; Chao, T.T.; Theobald, P.K.

    1982-01-01

    A hot hydroxylamine hydrochloride (H-Hxl) extraction in 25% acetic acid is compared with the commonly used oxalic acid extraction as a method of anomaly enhancement for Cu and Zn in samples from two very different metal deposits and climatic environments. Results obtained on minus-80-mesh stream sediments from an area near the Magruder massive sulfide deposit in Lincoln County, Georgia, where the climate is humid subtropical, indicate that H-Hxl enhances the anomaly for Cu by a factor of 2 and for Zn by a factor of 1.5, compared to the oxalic method. Analyses of Fe oxide-coated rock samples from outcrops overlying the North Silver Bell porphyry copper deposit near Tucson, Arizona, where the climate is semi-arid to arid, indicate that both techniques effectively outline the zones of hydrothermal alteration. The H-Hxl extraction can also perform well in high-carbonate or high-clay environments, where other workers have suggested that oxalic acid is not very effective. Therefore, the H-Hxl method is recommended for general exploration use. ?? 1982.

  6. C3 Photosynthesis and Crassulacean Acid Metabolism in a Kansas Rock Outcrop Succulent, Talinum calycinum Engelm. (Portulacaceae) 1

    PubMed Central

    Martin, Craig E.; Zee, Aaron Klaas

    1983-01-01

    The potential for Crassulacean acid metabolism (CAM) was investigated in the sandstone outcrop succulent Talinum calycinum in central Kansas. Field studies revealed CAM-like diurnal acid fluctuations in these plants. These fluctuations persisted under all moisture and temperature regimes in the laboratory. Despite this CAM-like acid metabolism, simultaneous gravimetric determinations of day- and nighttime transpiration rates indicated the presence of a C3 gas exchange pattern. Subsequent analyses of diurnal CO2 and H2O exchange patterns under well-watered conditions and after 3, 5, and 7 days of drought confirmed these findings, though low rates of nocturnal CO2 uptake were observed on the fifth night after continuous drought. Finally, the δ13C/12C value of this succulent, −27.8‰, emphasizes the insignificance of any nocturnal CO2 uptake in the lifelong accumulation of carbon in this species. Thus, it is proposed that T. calycinum is a C3 plant with some CAM characteristics, including the ability to re-fix respiratory CO2 at night under all moisture regimes, potentially resulting in a conservation of carbon, and occasionally to fix atmospheric CO2 at night. These findings may prove to be common among rock outcrop succulents. PMID:16663289

  7. Oxalic-acid leaching of rock, soil, and stream-sediment samples as an anomaly-accentuated technique

    USGS Publications Warehouse

    Alminas, Henry V.; Mosier, Elwin L.

    1976-01-01

    In many instances total-rock and sieved-soil and stream-sediment samples lack the sensitivity and contrast required for reconnaissance exploration and necessary in the search for blind ore deposits. Heavy-mineral concentrates incorporate the required sensitivity and contrast but are overly expensive for two reasons: time-consuming sample preparation is required to obtain them, and they cannot be easily derived from all bulk-sample types. Trace-metal-content comparisons of the oxalic-acid-leachable portions with heavy-mineral concentrates show that the leachates are equal to the heavy-mineral concentrates in sensitivity and contrast. Simplicity of preparation and the resultant cost savings are additional advantages of this proposed method.

  8. Uncertainty quantification and integration of machine learning techniques for predicting acid rock drainage chemistry: a probability bounds approach.

    PubMed

    Betrie, Getnet D; Sadiq, Rehan; Morin, Kevin A; Tesfamariam, Solomon

    2014-08-15

    Acid rock drainage (ARD) is a major pollution problem globally that has adversely impacted the environment. Identification and quantification of uncertainties are integral parts of ARD assessment and risk mitigation, however previous studies on predicting ARD drainage chemistry have not fully addressed issues of uncertainties. In this study, artificial neural networks (ANN) and support vector machine (SVM) are used for the prediction of ARD drainage chemistry and their predictive uncertainties are quantified using probability bounds analysis. Furthermore, the predictions of ANN and SVM are integrated using four aggregation methods to improve their individual predictions. The results of this study showed that ANN performed better than SVM in enveloping the observed concentrations. In addition, integrating the prediction of ANN and SVM using the aggregation methods improved the predictions of individual techniques.

  9. Comparing phosphorus mobilization strategies using Aspergillus niger for the mineral dissolution of three phosphate rocks.

    PubMed

    Schneider, K D; van Straaten, P; de Orduña, R Mira; Glasauer, S; Trevors, J; Fallow, D; Smith, P S

    2010-01-01

    Phosphorus deficiencies are limiting crop production in agricultural soils worldwide. Locally available sources of raw phosphate rock (PR) are being recognized for their potential role in soil fertility improvement. Phosphorus bioavailability is essential for the efficiency of PRs and can be increased by acid treatments. The utilization of organic acid producing micro-organisms, notably Aspergillus niger, presents a sustainable alternative to the use of strong inorganic acids, but acid production of A. niger strongly depends on the mineral content of the growth media. This study compared the phosphorus mobilization efficiency of two biological treatments, namely addition of acidic cell-free supernatants from A. niger cultivations to PRs and the direct cultivation of A. niger with PRs. The results show that addition of PR to cultivations leads to significant differences in the profile of organic acids produced by A. niger. Additions of PR, especially igneous rocks containing high amounts of iron and manganese, lead to reduced citric acid concentrations. In spite of these differences, phosphorus mobilization was similar between treatments, suggesting that the simpler direct cultivation method was not inferior. In addition to citric acid, it is suggested that oxalic acid contributes to PR solubilization in direct cultivations with A. niger, which would benefit farmers in developing countries where conventional fertilizers are not adequately accessible.

  10. Hydrogen Peroxide Formation and pH Changes at Rock-Water Interface during Stressing

    NASA Astrophysics Data System (ADS)

    Xie, S.; Kulahci, I.; Cyr, G.; Tregloan-Reed, J.; Balk, M.; Rothschild, L. J.; Freund, F. T.

    2008-12-01

    Common igneous and high-grade metamorphic rocks contain dormant defects, which become activated when stressed. They release electronic charge carriers, in particular defect electrons associated with O- states in a matrix of O2-. Known as 'positive holes' or pholes for short, the O- states can spread out of the stressed rock volume, travel along stress gradients over distances on the order of meters in the lab and probably over kilometers in the field. They carry a current, which can flow through meters of rock in the laboratory, probably tens of kilometers in the field. At rock-water interfaces the O- states turn into O radicals, which subtract H from H2O, forming OH- in the rock surface and PH radicals in the water. Two OH combine to H2O2. In the process the pH becomes more acidic. The discovery of H2O2 formation at rock-water interfaces as part of stress- activated currents on the tectonically active Earth may help us better understand the oxidation of the early Earth and the evolution of early Life.

  11. Diverse sources for igneous blocks in Franciscan melanges, California Coast Ranges

    SciTech Connect

    MacPherson, G.J. ); Phipps, S.P. ); Grossman, J.N. )

    1990-11-01

    Igneous blocks in Franciscan melanges are of three chemical-petrologic types: (1) tholeiitic basalts of both arc and spreading center origin, with depletions in light relative to heavy rare-earth elements, 3% > TiO{sub 2} > 1%, high Y/Zr and Y/Ti ratios, and relict augites that generally have low Al and Ti and well-defined iron-enrichment trends; (2) basalts of probable seamount origin with marked enrichments in light relative to heavy rare-earth elements, 5% > TiO{sub 2} > 1%, lower Y/Zr and Y/Ti than (1), and Ti-Al-rich augites showing little if any iron-enrichment trends; and (3) hypabyssal intrusives having SiO{sub 2} > 52%, TiO{sub 2} < 1%, flat or only slightly fractionated rare-earth-abundance patterns, and diopsidic augites that are very low in Ti and Al and show no iron-enrichment trends. All of the blocks are metamorphosed; most are undeformed pumpellyite-bearing greenstones, and a few contain sodic amphibole {plus minus} lawsonite {plus minus} sodic pyroxene. The melanges are probably olistostromal in origin, deriving their igneous block detritus both from the downgoing Pacific plate (ocean floor basalts and seamounts) and from the hanging wall of the Franciscan trench (basalts and arc-related silic intrusive rocks). The silicic intrusive rocks and some of the basalts are eroded fragments of the fore-arc crust that ultimately become the Coast Range Ophiolite. These fragments were incorporated into the Franciscan trench fill and subducted. Results suggest that the igneous blocks in ophiolitic melanges provide important information about melange formation and about the tectonics and paleogeography of the regions in which the melanges are found.

  12. Classification of mafic clasts from mesosiderites - Implications for endogenous igneous processes

    NASA Technical Reports Server (NTRS)

    Rubin, Alan E.; Mittlefehldt, David W.

    1992-01-01

    Results are presented from an analysis of 13 igneous pebbles from the Vaca Muerta, EET87500, and Bondoc mesosiderites, using electron microprobe and instrumental neutron activation techniques. These data, combined with literature data on compositions of 43 mesosiderite clasts were used to compile a classification scheme for the various types of mafic silicate clasts that occur in mesosiderites. These clasts were classified into five principal groups: (1) polygenic and monogenic cumulates (30 percent); (2) polygenic basalts (30 percent); (3) quench-textured rocks, comprising two compositional subgroups (those which resemble basaltic eucrites (5 percent), and those which resemble cumulate eucrites (2 percent)); (4) monogenic basalts (11 percent); and (5) ultramafic rocks, consisting mainly of large crystals of orthopyroxene (9 percent) or olivine (4 percent). The conditions under which these clasts were formed are discussed.

  13. A trishear model for the deformation of the Sudbury Igneous Complex, Canada

    NASA Astrophysics Data System (ADS)

    Lenauer, Iris; Riller, Ulrich

    2017-04-01

    The Sudbury Igneous Complex (SIC), Canada, is an impact-induced layered sheet of crystalline rocks deformed into an asymmetrical fold basin, the Sudbury Basin. The basin geometry at depth is largely unknown as few attempts were made to quantify displacement and rotation of layer contacts. We propose that the dip of layer contacts and foliation surfaces in the southern SIC can be approximated by trishear fault propagation folding. Trishear deformation accounts for: (1) angular discordances between upper and basal SIC contacts, (2) local overturning of the SIC, (3) progressive steepening of foliation surfaces from NW to SE, (4) strain gradient in the Sudbury Basin sedimentary rocks, and (5) thickness variations in SIC layers. Moreover, the South Range Shear Zone, a zone of moderately strong metamorphic fabrics, coincides with the surface manifestation of the proposed trishear zone. We demonstrate the use of structural data together with forward kinematic modelling to identify the strain distribution within the SIC, rotation of SIC contacts and thickness changes of SIC layers. Backward kinematic modelling provides information on the initial geometry of the SIC and is used to restore the shape of the igneous sheet, showing that the SIC was shortened by approximately 10 km in NW-SE diameter. Most of the shortening was accommodated by 40% reduction in the thickness of the upper SIC layer.

  14. Rho/ROCK acts downstream of lysophosphatidic acid receptor 1 in modulating P2X3 receptor-mediated bone cancer pain in rats

    PubMed Central

    Wu, Jing-xiang; Yuan, Xiao-min; Wang, Qiong; Wei, Wang

    2016-01-01

    Background Lysophosphatidic acid receptor 1 and Rho/ROCK signaling is implicated in bone cancer pain development. However, it remains unknown whether the two signaling pathways function together in P2X3 receptor-mediated bone cancer pain. Results In this study, using a rat model of bone cancer, we examined the expression of P2X3 and lysophosphatidic acid receptor 1 in rat dorsal root ganglion neurons and further dissected whether lysophosphatidic acid receptor 1 and Rho/ROCK-mediated pathways interacted in modulating rat pain behavior. Bone cancer was established by inoculating Walker 256 cells into the left tibia of female Wistar rats. We observed a gradual and yet significant decline in mean paw withdrawal threshold in rats with bone cancer, but not in control rats. Our immunohistochemical staining revealed that the number of P2X3- and lysophosphatidic acid receptor 1-positive dorsal root ganglion neurons was significantly greater in rats with bone cancer than control rats. Lysophosphatidic acid receptor 1 blockade with VPC32183 significantly attenuated decline in mean paw withdrawal threshold. Flinching behavior test further showed that lysophosphatidic acid receptor 1 inhibition with VPC32183 transiently but significantly attenuated α,β-meATP-induced increase in paw lift time per minute. Rho inhibition by intrathecal BoTXC3 caused a rapid reversal in decline in mean paw withdrawal threshold of rats with bone cancer. Flinching behavior test showed that BoTXC3 transiently and significantly attenuated α,β-meATP-induced increase in paw lift time per minute. Similar findings were observed with ROCK inhibition by intrathecal Y27632. Furthermore, VPC32183 and BoTXC3 effectively aborted the appearance of lysophosphatidic acid-induced calcium influx peak. Conclusions Lysophosphatidic acid and its receptor LPAR1, acting through the Rho-ROCK pathway, regulate P2X3 receptor in the development of both mechanical and spontaneous pain in bone cancer. PMID:27094551

  15. Deep structure of the Mount Amram igneous complex, interpretation of magnetic and gravity data

    NASA Astrophysics Data System (ADS)

    Shirman, Boris; Rybakov, Michael; Beyth, Michael; Mushkin, Amit; Ginat, Hanan

    2015-03-01

    The Mt Amram igneous complex (AIC) represents northern tip of the Neoproterozoic Arabian Nubian Shield (ANS). For the first time the AIC deep structure was studied using the gravity, aero and ground magnetic, magnetic susceptibility and density measurements and geological data. Analysing all available data at the Amram area we concluded what only monzonite body can be reason for gravity high and coinciding reduced to pole (RTP) maximum. Geological knowledge allowed suggesting its intrusive character and compact body form. Cluster of inverse solutions (Werner deconvolution) localized this body as initial model for forward modelling. Further iterations (23/4-D forward modelling) clarified the monzonite geometry and properties; the modelling allowed also to investigate the non-uniqueness and estimate also the confident intervals for final solution. The research consists three interconnected stages. At the detailed scale, ground magnetic data suggested three magmatic blocks of few hundred meters shifted dextral about 100 m along the Zefunut fault. Estimated accuracy for geometry of the magnetic bodies is a few tens metres. At the middle scale, quantitative gravity and magnetic interpretations provide model of the monzonite body, which is an order of magnitude more than the volume of the felsic rhyolites and granite rocks. Boundary of the whole monzonite body was estimated with accuracy as a hundred meters. As a result we suggest that the parent magma for the AIC is the monzonite, similar to the model suggested for the Timna Igneous Complex 12 km north of the AIC. The model developed can be applied to evaluate the subsurface volumes of the mafic magmatic rocks in adjacent locations. At the regional scale for exposed the Sinai and Arab Saudi Precambrian crystalline shield our approach allows to understand the apparent contradiction between geological predominantly granite composition (low magnetic rocks) and magnetic data. The aeromagnetic data show number strong

  16. Effect of igneous intrusive bodies on sedimentary thermal maturity

    SciTech Connect

    Wang, X.; Lerche, I.; Walter, C. )

    1989-09-01

    The high temperatures of igneous intrusives cause localized thermal maturity of sediments far in excess of the regional variation. Previous studies have shown that igneous bodies cool in less than about 1 million years for all but the most exceptional geological conditions. Three case studies are provided which show how the increase in thermal maturity around an igneous body can be used to assess the temperature of the intrusive at emplacement and also the time of intrusion. Corollative implications for localized hydrocarbon generation, migration, and accumulation are also discussed briefly.

  17. Evaluation of and new completion recommendations for a fractured, crystalline, igneous reservoir, Texas Panhandle

    SciTech Connect

    Weimer, B.A.; Manwaring, M.S. )

    1987-02-01

    In the Panhandle field of Texas, the lowest stratigraphic producing formation is a crystalline basement rock. The igneous rock is productive when it is naturally fractured sufficiently to hold hydrocarbons trapped in the same structure as the expansive Panhandle field. Research work to understand the crystalline reservoir better focused on the fracturing, mineralogy, and production potential of the basement interval. This trap is a true fractured reservoir; it has no more than 1% primary porosity in the nonfractured rock. The mineralogy of the host rock and fracture-filling minerals was established from drill and core samples. The host rock is a complex of granodiorite, dacite, and gabbroic diorite. Scanning electron microscopy, x-ray diffraction, and optical work confirmed the occurrence of at least 12 secondary fracture-fill minerals. Fluid inclusion analysis established formation temperatures for many of the minerals and allowed postulation of a detailed sequence of formation. The character of the fracture in differing host petrologies and the occurrence of clay minerals coating fracture surfaces were deemed to be critical factors in hydrocarbon production. New and specific enhancement treatments were designed for the subject reservoir, and these recommendations were used in a test well. Results from the test were favorable and appear to confirm the ideas formed from this work. The new recommended treatments are less expensive than current practices and indicate potential for greater ultimate recoveries of oil.

  18. Metasedimentary and igneous xenoliths from Tallante (Betic Cordillera, Spain): Inferences on crust-mantle interactions and clues for post-collisional volcanism magma sources

    NASA Astrophysics Data System (ADS)

    Bianchini, Gianluca; Braga, Roberto; Langone, Antonio; Natali, Claudio; Tiepolo, Massimo

    2015-04-01

    The deep seated xenolith association exhumed in the Pliocenic volcano of Tallante (Betic Cordillera, Spain) includes protogranular mantle peridotites, felsic (metasedimentary) crustal rocks, as well as cumulus igneous rocks such as norites and amphibole (± phlogopite)-clinopyroxenites. The whole xenolith suite equilibrated at the same pressure (0.7-0.9 GPa) representing the local crust-mantle boundary (MOHO) characterized by extreme lithological heterogeneity. This heterogeneity resulted from orogenic processes that induced the juxtaposition of crustal rocks (variably depleted in fusible components) within mantle domains including metasomes, as it is commonly observed in orogenic mantle massifs of the Mediterranean area. In this contribution, we report new mineral compositions of igneous parageneses recorded in these xenoliths, and we present Sr-Nd isotope data on both igneous and metasedimentary xenoliths that integrate those from the literature. Sr-Nd isotopes coherently indicate a restitic character of the metasedimentary xenoliths, which according to model ages were affected by partial melting in Paleozoic times. Sr-Nd isotopic errorchrons on the igneous xenoliths, on the other hand, qualitatively indicate Tertiary ages, which are corroborated by U-Pb zircon datings of one norite xenolith and two composite xenoliths having zircon-bearing norite veinlets. The new data are discussed proposing that MOHO lithologies of Tallante could provide significant source compositions for the genesis of the Neogene volcanics of the Betic area, which included calcalkaline lavas as well as more potassic products such as lamproites.

  19. Transition element distribution in stony meteorites and in terrestrial and lunar rocks.

    NASA Technical Reports Server (NTRS)

    Mason, B.; Jarosewich, E.; Nelen, J.

    1971-01-01

    Discussion of the distribution of the transition elements (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn) among the individual minerals of stony meteorites, and comparison with data on comparable lunar and terrestrial minerals. As an example of meteorite distribution patterns, data on the Modoc meteorite are presented. For the lunar rocks, microprobe data are used, along with published information from other investigators. For comparison with terrestrial igneous rocks, Skaergaard intrusion rocks are used. They present some striking analogies in mineralogy and petrology with the lunar igneous rocks and are thus peculiarly suitable for this cross comparison.

  20. Structural lineaments in the basement rocks of the central Eastern Desert, Egypt

    NASA Astrophysics Data System (ADS)

    Kamel, A. F.

    The Egyptian basement rocks outcrop in Eastern Desert, southern Sinai and southwestern Desert. The rocks belong to Precambrian and consist of igneous and metamorphic rocks which are characterized by crystalline character. Not much work has been done on the tectonics and structure of the basement rocks in Eastern Desert. The present work is a photogeological interpretation of the structural lineaments representing dykes, faults and joints in central Eastern Desert to differentiate between igneous and metamorphic rocks. The photogeological interpretation was carried out using normal aerial photographs scale 1:40 000 and photomosaics scale 50 000. The main trends of lineaments in the studied area are: E-W, ENE-WSW and WNW-ESE, constituting 58.4% of the total length and 54.5% of the total number. Correlating the structural lineaments in igneous rocks of Gebel El Bakriya locality with those in the metamorphic rocks of Gebel Abu Mireiwa shows that there is a marked difference between the two types. Lineaments in igneous rocks are elongated and widely spaced while those in metamorphic rocks are short and closely spaced. The different trends of joints in igneous rocks can be arranged as follows: WNW>E-W>NW>NNW>ENE>NE>N-S>NNE while the different trends of lineaments in metamorphic rocks can be arranged as follows: E-W>ENE>WNW>NW>NNW>NE>N-S>NNE. Comparison between the structural contour maps constructed for the total length of all lineaments and those representing joints in igneous and metamorphic rocks indicates that igneous rocks have lower density of lineaments than metamorphic rocks. The total length of all lineaments in Gebel El Bakriya amounts to 375 km, while lineaments representing joints have a total length of 150 km. In the metamorphic rocks of Gebel Abu Mireiwa, the total length of all lineaments is 425 km and those representing joints have a total length of 175 km. It was found that there is a relationship between the structural lineaments and radioactivity of

  1. Igneous mineralogy at Bradbury Rise: The first ChemCam campaign at Gale crater

    NASA Astrophysics Data System (ADS)

    Sautter, V.; Fabre, C.; Forni, O.; Toplis, M. J.; Cousin, A.; Ollila, A. M.; Meslin, P. Y.; Maurice, S.; Wiens, R. C.; Baratoux, D.; Mangold, N.; Le Mouélic, S.; Gasnault, O.; Berger, G.; Lasue, J.; Anderson, R. A.; Lewin, E.; Schmidt, M.; Dyar, D.; Ehlmann, B. L.; Bridges, J.; Clark, B.; Pinet, P.

    2014-01-01

    and compositional analyses using Chemistry Camera (ChemCam) remote microimager and laser-induced breakdown spectroscopy (LIBS) have been performed on five float rocks and coarse gravels along the first 100 m of the Curiosity traverse at Bradbury Rise. ChemCam, the first LIBS instrument sent to another planet, offers the opportunity to assess mineralogic diversity at grain-size scales (~ 100 µm) and, from this, lithologic diversity. Depth profiling indicates that targets are relatively free of surface coatings. One type of igneous rock is volcanic and includes both aphanitic (Coronation) and porphyritic (Mara) samples. The porphyritic sample shows dark grains that are likely pyroxene megacrysts in a fine-grained mesostasis containing andesine needles. Both types have magnesium-poor basaltic compositions and in this respect are similar to the evolved Jake Matijevic rock analyzed further along the Curiosity traverse both with Alpha-Particle X-ray Spectrometer and ChemCam instruments. The second rock type encountered is a coarse-grained intrusive rock (Thor Lake) showing equigranular texture with millimeter size crystals of feldspars and Fe-Ti oxides. Such a rock is not unique at Gale as the surrounding coarse gravels (such as Beaulieu) and the conglomerate Link are dominated by feldspathic (andesine-bytownite) clasts. Finally, alkali feldspar compositions associated with a silica polymorph have been analyzed in fractured filling material of Preble rock and in Stark, a putative pumice or an impact melt. These observations document magmatic diversity at Gale and describe the first fragments of feldspar-rich lithologies (possibly an anorthosite) that may be ancient crust transported from the crater rim and now forming float rocks, coarse gravel, or conglomerate clasts.

  2. Characterization of Arctic Highly Magnetic Domains - the Geophysical Expression of Inferred Large Igneous Province(s)

    NASA Astrophysics Data System (ADS)

    Saltus, R. W.; Oakey, G.; Miller, E. L.; Jackson, R.

    2012-12-01

    the broader Arctic region, the term High Arctic Large Igneous Province (HALIP) refers to (now) scattered parts of a major plume-type basaltic eruption, many of which also show as magnetic highs on the current data compilation. Rocks that contribute to this province have been mapped in Arctic Canada, Greenland, Svalbard, Franz Josef Land and the DeLong Islands. Most HALIP volcanic rocks do not have reliable reported radiometric ages but seem to indicate two pulses of magmatism of around 130-120 Ma and 90-80 Ma. There are many fundamental open questions regarding the evolution of the Arctic, particularly for the opening and development of the Amerasian side. The mafic igneous rocks and their roots that make up large igneous provinces are a good target for regional magnetic interpretation. Our goal is to use a data-driven approach to characterize the geometries and volumes these features as the expression of major mafic (basaltic) elements to aid in tectonic reconstruction and understanding.

  3. Chemistry of micas and chlorite in Proterozoic acid metavolcanics and associated rocks from the Hästefält area, Norberg ore district, central Sweden

    NASA Astrophysics Data System (ADS)

    Aldahan, A. A.; Ounchanum, P.; Morad, S.

    1988-09-01

    Microprobe analyses are performed on micas (biotite, muscovite and phlogopite) and chlorite from 1.9 1.8 Ga acid K- or Na-rich metavolcanics, cordierit-emica schists and manganiferous rocks from the Hästefält area in central Sweden. The results indicate that Fe-rich biotites and muscovites containing ≥10 to ≤25% celadonite and/or pyrophyllite are common in the K- and Na-rich metavolcanics. In the cordierite-mica schists the biotites are Mg-rich and the muscovites contain less than 10% celadonite and/or pyrophyllite. The predominant mica in the manganiferous rocks are phlogopite and less frequent rather pure muscovite. The chlorites show a wide range in composition, but principally those occurring in the K- and Na-rich metavolcanics are brunsvigite and diabantite and those in the cordierite-mica schists and the manganiferous rocks are mainly sheridanite and clinochlore. The chlorites of the manganiferous rocks show enrichment in Mn compared to those in other rock types. In general the compositional variations in the micas and less commonly chlorites are strongly controlled by rock type and fluid chemistry, particularly with respect to the ratio of FeO/(FeO+MgO). Estimates of maximum prograde metamorphic temperature, based on phyllosilicates and co-existing cordierite and garnets, indicate a value of up to 500° C.

  4. Abraded Target on Rock 'Champagne' in Gusev Crater

    NASA Technical Reports Server (NTRS)

    2005-01-01

    NASA's Mars Exploration Rover Spirit took this microscopic image of a target called 'Bubbles' on a rock called 'Champagne' after using its rock abrasion tool to grind a hole through the rock's outer surface. The circular area where the rock's interior is exposed is about 5 centimeters (2 inches) across. This rock is different from rocks out on the plains of Gusev Crater but is similar to other rocks in this area of the 'Columbia Hills' in that it rich in phosphorus. Plagioclase, a mineral commonly found in igneous rocks, is also present in these rocks, according to analysis with Spirit's miniature thermal emission spectrometer. By using the rover's alpha particle X-ray spectrometer to collect data for multiple martian days, or sols, scientists are also beginning to get measurements of trace elements in the rocks. Spirit took the images that are combined into this mosaic on sol 358 (Jan. 3, 2005).

  5. Lunar rock compositions and some interpretations.

    PubMed

    Engel, A E; Engel, C G

    1970-01-30

    Samples of igneous "gabbro," "basalt," and lunar regolith have compositions fundamentally different from all meteorites and terrestrial basalts. The lunar rocks are anhydrous and without ferric iron. Amounts of titanium as high as 7 weight percent suggest either extreme fractionation of lunar rocks or an unexpected solar abundance of titanium. The differences in compositions of the known, more "primitive" rocks in the planetary system indicate the complexities inherent in defining the solar abundances of elemizents and the initial compositions of the earth and moon.

  6. Lunar rock compositions and some interpretations

    USGS Publications Warehouse

    Engel, A.E.J.; Engel, C.G.

    1970-01-01

    Samples of igneous "gabbro," "basalt," and lunar regolith have compositions fundamentally different from all meteorites and terrestrial basalts. The lunar rocks are anhydrous and without ferric iron. Amounts of titanium as high as 7 weight percent suggest either extreme fractionation of lunar rocks or an unexpected solar abundance of titanium. The differences in compositions of the known, more "primitive" rocks in the planetary system indicate the complexities inherent in defining the solar abundances of elements and the initial compositions of the earth and moon.

  7. Insights into Igneous Geochemistry from Trace Element Partitioning

    NASA Technical Reports Server (NTRS)

    Jones, J. H.; Hanson, B. Z.

    2001-01-01

    Partitioning of trivalent elements into olivine are used to explore basic issues relevant to igneous geochemistry, such as Henry's law. Additional information is contained in the original extended abstract.

  8. Igneous geology of the Carlin trend, Nevada: The importance of Eocene magmatism in gold mineralization

    NASA Astrophysics Data System (ADS)

    Ressel, Michael Walter, Jr.

    Igneous rocks of five ages are present in the Carlin trend, Nevada, and include: (1) Paleozoic basalt of the Roberts Mountains allochthon, (2) the Jurassic (˜158 Ma) Goldstrike intrusive complex, which includes the Goldstrike diorite laccolith and abundant dikes and sills, (3) a Cretaceous (112 Ma) granite stock, (4) lavas and intrusions of the Emigrant Pass volcanic field and widespread epizonal plugs and dikes of Eocene (˜40-36 Ma) age that range from rhyolite through basalt, and (5) Miocene (15 Ma) rhyolite lava and tuff. Jurassic and Eocene igneous rocks are by far the most important volumetrically and are spatially associated with nearly all ore deposits of the Carlin trend. This study focuses on the field relations, isotopic dating, and geochemistry of Eocene dikes that intrude sedimentary rocks in many deposits of the Carlin trend, because they are the youngest pre-mineral rocks and have simpler alteration histories than other host rocks. In the Beast, Genesis, Deep Star, Betze-Post, Rodeo-Goldbug, Meikle-Griffin, and Dee-Storm deposits, Eocene dikes are altered, commonly mineralized, and locally constitute ore. Gold-bearing dikes and sedimentary rocks have similar ore mineralogy, including arsenian pyrite, marcasite, and arsenopyrite, with late barite and stibnite. At Beast, as much as half the ore is hosted in a 37.3 Ma rhyolite dike. Post-gold alunite is ˜18.6 Ma. At Meikle and Griffin, porphyritic dacite dikes yield concordant U/Pb zircon and 40Ar/39Ar biotite emplacement ages of ˜39.2 Ma, and illite from the same QSP-altered dacite, with as much 9 ppm Au, yields similar, although imprecise 40Ar/39Ar ages. Thus, gold mineralization at these deposits closely followed emplacement of Eocene dikes. Carlin-type gold deposits in northeastern Nevada have been variously interpreted as partly syngenetic with Paleozoic carbonate rocks, products of Mesozoic contraction and metamorphism with or without significant magmatism, and of Tertiary age and related or

  9. Regional mapping of hydrothermally altered igneous rocks along the Urumieh-Dokhtar, Chagai, and Alborz Belts of western Asia using Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data and Interactive Data Language (IDL) logical operators: a tool for porphyry copper exploration and assessment: Chapter O in Global mineral resource assessment

    USGS Publications Warehouse

    Mars, John L.; Zientek, M.L.; Hammarstrom, J.M.; Johnson, K.M.; Pierce, F.W.

    2014-01-01

    The ASTER alteration map and corresponding geologic maps were used to select circular to elliptical patterns of argillic- and phyllic-altered volcanic and intrusive rocks as potential porphyry copper sites. One hundred and seventy eight potential porphyry copper sites were mapped along the UDVB, and 23 sites were mapped along the CVB. The potential sites were selected to assist in further exploration and assessments of undiscovered porphyry copper deposits.

  10. Selective Precipitation of Thorium lodate from a Tartaric Acid-Hydrogen Peroxide Medium Application to Rapid Spectrophotometric Determination of Thorium in Silicate Rocks and in Ores

    USGS Publications Warehouse

    Grimaldi, F.S.

    1957-01-01

    This paper presents a selective iodate separation of thorium from nitric acid medium containing d-tartaric acid and hydrogen peroxide. The catalytic decomposition of hydrogen peroxide is prevented by the use of 8quinolinol. A few micrograms of thorium are separated sufficiently clean from 30 mg. of such oxides as cerium, zirconium, titanium, niobium, tantalum, scandium, or iron with one iodate precipitation to allow an accurate determination of thorium with the thoronmesotartaric acid spectrophotometric method. The method is successful for the determination of 0.001% or more of thorium dioxide in silicate rocks and for 0.01% or more in black sand, monazite, thorite, thorianite, eschynite, euxenite, and zircon.

  11. Some Environmental Consequences of Large Igneous Provinces

    NASA Astrophysics Data System (ADS)

    Coffin, M. F.

    2009-12-01

    The formation of large igneous provinces (LIPs)—continental flood basalts, ‘volcanic’ margins, and oceanic plateaus—may impact the atmosphere, oceans, and biosphere by rapidly releasing huge amounts of particulates, magmatic volatiles (CO2, SO2, Cl, F, etc.), and potentially volatiles (CO2, CH4, SO2, etc.) from intruded sediments (e.g., carbonates, organic-rich shales, evaporites). A key factor affecting the magnitude of volatile release is whether eruptions are subaerial or marine; hydrostatic pressure inhibits vesiculation and degassing of relatively soluble volatile components (H2O, S, Cl, F) in deep water submarine eruptions, although low solubility components (CO2, noble gases) are mostly degassed even at abyssal depths. Directly or indirectly, such injections may cause changes in the atmosphere/ocean system that can lead to perturbations of atmosphere/ocean chemistry, circulation, ecology, and biological productivity. These changes can be global in extent, particularly if environmental conditions were at or near a threshold state or tipping point. LIPs may have been responsible for some of the most dramatic and rapid changes in the global environment. For example, between ~145 and ~50 Ma, the global ocean was characterized by chemical and isotopic variations (especially in C and Sr isotope ratios, trace metal concentrations, and biocalcification), relatively high temperatures, high relative sea level, episodic deposition of black shales (oceanic anoxic events), high production of hydrocarbons, mass extinctions of marine organisms, and radiations of marine flora and fauna. Temporal correlations between the intense pulses of igneous activity associated with LIP formation and environmental changes suggest more than pure coincidence. The 1783-84 eruption of Laki on Iceland provides the only historical record of the type of volcanism that constructs transient LIPs. Although Laki produced a basaltic lava flow representing only ~1% of the volume of a typical

  12. Pseudomonas fluorescens ATCC 13525 containing an artificial oxalate operon and Vitreoscilla hemoglobin secretes oxalic acid and solubilizes rock phosphate in acidic alfisols.

    PubMed

    Yadav, Kavita; Kumar, Chanchal; Archana, G; Naresh Kumar, G

    2014-01-01

    Oxalate secretion was achieved in Pseudomonas fluorescens ATCC 13525 by incorporation of genes encoding Aspergillus niger oxaloacetate acetyl hydrolase (oah), Fomitopsis plaustris oxalate transporter (FpOAR) and Vitreoscilla hemoglobin (vgb) in various combinations. Pf (pKCN2) transformant containing oah alone accumulated 19 mM oxalic acid intracellularly but secreted 1.2 mM. However, in the presence of an artificial oxalate operon containing oah and FpOAR genes in plasmid pKCN4, Pf (pKCN4) secreted 13.6 mM oxalate in the medium while 3.6 mM remained inside. This transformant solubilized 509 μM of phosphorus from rock phosphate in alfisol which is 4.5 fold higher than the Pf (pKCN2) transformant. Genomic integrants of P. fluorescens (Pf int1 and Pf int2) containing artificial oxalate operon (plac-FpOAR-oah) and artificial oxalate gene cluster (plac-FpOAR-oah, vgb, egfp) secreted 4.8 mM and 5.4 mM oxalic acid, released 329 μM and 351 μM P, respectively, in alfisol. The integrants showed enhanced root colonization, improved growth and increased P content of Vigna radiata plants. This study demonstrates oxalic acid secretion in P. fluorescens by incorporation of an artificial operon constituted of genes for oxalate synthesis and transport, which imparts mineral phosphate solubilizing ability to the organism leading to enhanced growth and P content of V. radiata in alfisol soil.

  13. Igneous and Sedimentary Compositions from Four Landing Sites on Mars from the Alpha Particle X-Ray Spectrometer (APXS)

    NASA Technical Reports Server (NTRS)

    Gellert, R.; Arvidson, R. E.; Clark, B. C.; Ming, D. W.; Mittlefehldt, D. W.; Morris, R. W.; Squyres, S. W.; VanBommel, S.; Yen, A. S.

    2016-01-01

    The APXS - supported and promoted strongly by Heinrich Waenke - on all four Mars Rovers has returned compositional data from about 1000 rocks and soil targets along the combined traverses of over 60 kilometers. Providing precise and accurate bulk chemistry with typically 16 quantified elements, the APXS is a powerful and versatile tool that when combined with the ability to traverse to key rocks and soils has provided critical information needed to understand the geologic evolution of Mars. APXS data allow comparisons among landing sites, provide ground truth for orbiters and connections back to SNC meteorites. The soils and dust are basaltic in character and represent the average Mars composition similar to Adirondack basalts from Gusev crater but with unambiguous elevated and correlated S, Cl and Zn contents. At all four landing sites the APXS found several rocks with a felsic composition. The similarity is best assessed in a logarithmic ratio plot of rock normalized to the average soil composition (Fig.1). High alkaline, Al, and low Mg, Fe, low S, Cl and Ni, Zn as well as an Fe/Mn ratio of approximately 50 indicate a likely unaltered and igneous origin. Sediments, e.g. the Burns formation, with approximately 25 wt% SO3 at Meridiani Planum have been documented over 10s of kilometers (Fig. 2). This formation is compositionally homogeneous, but showing the removal of MgSO4 and a threefold increase in Cl downhill in 2 craters. The degraded rim of the Noachian crater Endeavour resembles average Mars crust, with local Ca, Mg and Fe sulfate alteration and elevated Mn, some felsic rocks, and high Al, Si and low Fe rocks, possibly indicating clays. Unusual soils at Gusev crater in the area surrounding Home Plate include some very rich in ferric sulfate salts (up to 35 wt% SO3) and some with 90% wt% SiO2, possibly indicating fumerolic activities. Rocks in the Columbia Hills show significant signs of alteration including elevated S, Cl and Br in the abraded interior. At

  14. Acid rock drainage passive remediation: Potential use of alkaline clay, optimal mixing ratio and long-term impacts.

    PubMed

    Plaza, Fernando; Wen, Yipei; Perone, Hanna; Xu, Yi; Liang, Xu

    2017-01-15

    Acid rock drainage (ARD) is one of the most adverse environmental problems of the mining industry. Surface and ground water affected by this pollution are characterized by their acidity and the high content of sulfates and metals/metalloids. In this study, alkaline clay (AC), an industrial waste with a high alkalinity, which is utilized in the alumina refining process, was used as the remediation material to inhibit pyrite oxidation in waste coal piles. Through a series of laboratory experiments (static and kinetic), complemented with field measurements and geochemical modeling, three important issues associated with this passive and sustainable ARD remediation method were investigated: 1) the potential use of alkaline clay as an ARD remediation material, 2) the adequate alkaline clay/coal refuse mixing ratio (AC/CR) to ensure pH values close to neutral conditions, and, 3) the implications for long-term performance, in terms of the trends of the main parameters involved in this process such as pH, concentrations of sulfate, iron and other dissolved contaminants. Both field measurements and the samples used for the experiments came from a local waste coal site. Through the analysis of the field measurements and the outcome of the laboratory experiments, AC proved to be an effective remediation material for ARD. Compared to those found in mine tailings, the concentrations of contaminants such as iron, manganese or sulfate were significantly reduced with this remediation approach. Moreover, results suggest a reliable long-term stability of the remediation (i.e. neutral pH conditions are maintained), thus enhancing the generation of iron precipitates that could produce pyrite grain coating. These processes also made the amended layer less porous, thus increased water retention and hindered oxygen diffusion.

  15. Microbacter margulisiae gen. nov., sp. nov., a propionigenic bacterium isolated from sediments of an acid rock drainage pond.

    PubMed

    Sánchez-Andrea, Irene; Sanz, Jose Luis; Stams, Alfons J M

    2014-12-01

    A novel anaerobic propionigenic bacterium, strain ADRI(T), was isolated from sediment of an acid rock drainage environment (Tinto River, Spain). Cells were small (0.4-0.6×1-1.7 µm), non-motile and non-spore-forming rods. Cells possessed a Gram-negative cell-wall structure and were vancomycin-resistant. Strain ADRI(T) utilized yeast extract and various sugars as substrates and formed propionate, lactate and acetate as major fermentation products. The optimum growth temperature was 30 °C and the optimum pH for growth was pH 6.5, but strain ADRI(T) was able to grow at a pH as low as 3.0. Oxidase, indole formation, and urease and catalase activities were negative. Aesculin and gelatin were hydrolysed. The predominant cellular fatty acids of strain ADRI(T) were anteiso-C15 : 0 (30.3 %), iso-C15 : 0 (29.2 %) and iso-C17 : 0 3-OH (14.9 %). Major menaquinones were MK-8 (52 %) and MK-9 (48 %). The genomic DNA G+C content was 39.9 mol%. Phylogenetically, strain ADRI(T) was affiliated to the family Porphyromonadaceae of the phylum Bacteroidetes. The most closely related cultured species were Paludibacter propionicigenes with 16S rRNA gene sequence similarity of 87.5 % and several species of the genus Dysgonomonas (similarities of 83.5-85.4 % to the type strains). Based on the distinctive ecological, phenotypic and phylogenetic characteristics of strain ADRI(T), a novel genus and species, Microbacter margulisiae gen. nov., sp. nov., is proposed. The type strain is ADRI(T) ( = JCM 19374(T) = DSM 27471(T)).

  16. Geochemistry of the Kalkarindji Magmas: Insights into the Source of the Oldest Phanerozoic Large Igneous Province

    NASA Astrophysics Data System (ADS)

    Ware, B. D.; Jourdan, F.; Hodges, K.; Tessalina, S.; Chiaradia, M.; Evins, L.; Gole, M.

    2014-12-01

    The Kalkarindji continental flood basalt province (CFBP) of northern Australia is the oldest Phanerozoic large igneous province (LIP) in the world. The extent of this Middle Cambrian LIP has been estimated to at least 2.1 x 106 km2 with exposures in Western Australia, Northern Territory, Queensland, and South Australia. The research into Kalkarindji is still in its infancy with only a handful of studies published. The rocks of the Kalkarindji province occur as lava flows, sills, dykes, and volcanic tuffs. Kalkarindji has been linked to an extinction event at the Early-Middle Cambrian boundary. The Kalkarindji province displays Low-Ti values and high SiO2 values compared to other large igneous provinces, enriched 87Sr/86Sr values, and low 187Os/188Os. This project presents a large data set of new geochemical analyses of the various constituents of the Kalkarindji CFBP. Source mixing calculations, assimilation and fractionation models, coupled with Monte Carlo simulations were carried out to understand the petrogenesis of the province. The trace element and 87Sr/86Sr values indicate a contribution of enriched crustal-like material into the source region; however, the Os values fall into typical mantle ranges. These geochemical patterns suggest that the mantle source(s) of the Kalkarindji CFBP has been directly enriched at some stage of history, before the emplacement of the province. This study will provide further insights into the magma source and origin processes needed to create one of the world's largest and oldest Phanerozoic large igneous provinces.

  17. U.S. Geological Survey research in Handcart Gulch, Colorado—An alpine watershed with natural acid-rock drainage

    USGS Publications Warehouse

    Manning, Andrew H.; Caine, Jonathan Saul; Verplanck, Philip L.; Bove, Dana J.; Kahn, Katherine G.

    2009-01-01

    Handcart Gulch is an alpine watershed along the Continental Divide in the Colorado Rocky Mountain Front Range. It contains an unmined mineral deposit typical of many hydrothermal mineral deposits in the intermountain west, composed primarily of pyrite with trace metals including copper and molybdenum. Springs and the trunk stream have a natural pH value of 3 to 4. The U.S. Geological Survey began integrated research activities at the site in 2003 with the objective of better understanding geologic, geochemical, and hydrologic controls on naturally occurring acid-rock drainage in alpine watersheds. Characterizing the role of groundwater was of particular interest because mountain watersheds containing metallic mineral deposits are often underlain by complexly deformed crystalline rocks in which groundwater flow is poorly understood. Site infrastructure currently includes 4 deep monitoring wells high in the watershed (300– 1,200 ft deep), 4 bedrock (100–170 ft deep) and 5 shallow (10–30 ft deep) monitoring wells along the trunk stream, a stream gage, and a meteorological station. Work to date at the site includes: geologic mapping and structural analysis; surface sample and drill core mineralogic characterization; geophysical borehole logging; aquifer testing; monitoring of groundwater hydraulic heads and streamflows; a stream tracer dilution study; repeated sampling of surface and groundwater for geochemical analyses, including major and trace elements, several isotopes, and groundwater age dating; and construction of groundwater flow models. The unique dataset collected at Handcart Gulch has yielded several important findings about bedrock groundwater flow at the site. Most importantly, we find that bedrock bulk permeability is nontrivial and that bedrock groundwater apparently constitutes a substantial fraction of the hydrologic budget. This means that bedrock groundwater commonly may be an underappreciated component of the hydrologic system in studies of

  18. Detection and Characterization of Ultrafine Fe-as-pb Colloids In Acid Rock Drainage Solution From An Ore Mine

    NASA Astrophysics Data System (ADS)

    Zänker, H.; Moll, H.; Richter, W.; Brendler, V.; Hennig, C.; Reich, T.; Kluge, A.; Hüttig, G.

    The processes of sulfide oxidation, water acidification and water mineralization in abandoned ore mines are closely associated with the existence of gangue fissures in the host rock that contain clay minerals and finely-divided sulfide ores. These fissures release highly mineralized, red-colored acid rock drainage (ARD) solutions which can be collected from pools in front of the fissures. ARD solution from an abandoned Zn-Pb-A g mine at Freiberg, Germany, (pH 2.7, sulfate concentration 411 mmol/l, Fe concentration 93,5 mmol/l) was nvestigated by photon correlation i spectroscopy, centrifugation, filtration, ultrafiltration, scanning electron microscopy, ICP-MS, AAS, ion chromatography, TOC analysis and X-ray absorption fine structure (EXAFS) spectroscopy. The question was if this ARD solution contains colloidal particles of the lower nanometer range or if it is particle-free after the common filtration through a 450-nm filter. We found that there is a small amount (about 20 mg/l) of submicron particles of about 100 nm in size. However, the major colloidal component was shown to be a population of ultrafine particles of less than 5 nm. The concentration of these particles is about 1 g/l. They consist of Fe, As and Pb compounds. According to EXAFS spectroscopy, their most probable mineralogical composition is a mixture of hydronium jarosite (HFe3(SO4)2(OH)6) and schwertmannite (ideally Fe8O8(OH)6SO 4). We also observed the formation of a relatively coarse precipitate of a similar mineralogy in the colloidal solution over a time span of months. The ultrafine colloids are obviously an intermediate in the formation process of the long-term precipitate. The arsenic is probably bound onto the ultrafine colloidal particles as a bidentate binuclear ars enate surface complex (inner-sphere complex). However, the transformation of the colloids into the more aggregated long-term precipitate leads to the incorporation of the arsenic into the interior of the iron hydroxy sulfate

  19. Optimization of the Acetic Acid method for microfossil extraction from lithified carbonate rocks: Examples from the Jurassic and Miocene of Saudi Arabia

    NASA Astrophysics Data System (ADS)

    Chan, Septriandi; Malik, Muhammad; Kaminski, Michael; Babalola, Lamidi

    2016-04-01

    We report the first ever use of the acetic acid processing method for the extraction of microfossils from indurated limestones in Saudi Arabia. Two different limestone samples from Middle Jurassic and Middle Miocene formation in Saudi Arabia were tested under different concentrations of acid from 50% to 100% and with processing times from 2 hours to 10 hours, in an attempt to optimize the processing methodology. The recovery of acid residues shows a similar trend for both Jurassic and Miocene samples. The weight percentage of residue particle size > 1 mm decreases as acid concentration increases, especially in the 50 to 80% acid concentration range, and the weight percentage of the smallest size particles >0.063 mm increases as acid concentration increases. The small fraction of residue between 0.50 - 0.063 mm was split into 3 g subsamples and picked for microfossils in order to assess their preservation. All concentrations of acetic acid tested show promising results for both the Jurassic Dhruma and Miocene Dam formation carbonates. Higher acid concentrations with longer reaction times yield better recovery than higher concentrations with less reaction time. Based on our experiment, we recommended a 60% concentration of acetic acid to be the optimal concentration for use on routine micropaleontological samples of Saudi Arabian carbonate rocks. By lowering the concentration of acetic acid from 80% to 60%, the consumption of acid is reduced without compromising the recovery of microfossils, and the sample can be processed in a more environmentally friendly manner.

  20. Paleomagnetism of large igneous provinces: case-study from West Greenland, North Atlantic igneous province

    NASA Astrophysics Data System (ADS)

    Riisager, Janna; Riisager, Peter; Pedersen, Asger Ken

    2003-09-01

    We present new paleomagnetic and multi-model stereo photogrammetry data from lava sequences in the West Greenland part of the North Atlantic igneous province (NAIP). The joint analyses of paleomagnetic and photogrammetric data yield a well-defined paleomagnetic pole located at Lat=73.6°N, Long=160.5°E ( N=44, α95=6.2°, K=13.1; age ˜61-55 Ma), which is statistically indistinguishable from a pole recently obtained for the Eurasian part of the NAIP on Faroe Islands [Riisager et al., Earth Planet. Sci. Lett. 201 (2002) 261-276]. Combining the two datasets we obtain a joint NAIP paleomagnetic pole in Greenland coordinates: Lat=71.1°N, Long=161.1°E ( N=87, α95=4.3°, K=13.6; age ˜61-54 Ma). The results presented here represent the first study in which photogrammetry profiles were photographed at the exact same locations where paleomagnetic fieldwork was carried out, and a direct flow-to-flow comparison of the two datasets is possible. Photogrammetry is shown to be particularly useful because of (i) highly precise dip/strike measurements and (ii) detailed 'field observations' that can be made in the laboratory. Highly precise determination of the structural attitude of well-exposed Kanisut Mb lava sequences demonstrates that their apparently reliable in-field dip/strike measurements typically are up to ˜6° wrong. Erroneous dip/strike readings are particularly problematic as they offset paleomagnetic poles without affecting their confidence limits. Perhaps more important for large igneous provinces is the recognition of a variable temporal relationship between consecutive lava flows. We demonstrate how correct interpretation of paleosecular variation, facilitated by the detailed photogrammetry analysis, is crucial for the rapidly emplaced Vaigat Formation lavas. Inaccurate tectonic correction, non-averaged paleosecular variation and unrecognized excursional directions may, perhaps, explain why coeval paleomagnetic poles from large igneous provinces are often

  1. Granodiorite Pluton Formation at the Mid-Cenozoic Never Summer Igneous Complex, North-Central Colorado

    NASA Astrophysics Data System (ADS)

    Jacob, K. H.; Farmer, G.

    2012-12-01

    Field observations, major- and trace-element geochemistry, and Sr and Nd isotopic data were used to assess the petrogenesis of epizonal intrusive rocks and related volcanic rocks from the ~28 Ma Never Summer igneous complex in north-central Colorado. Intrusive igneous rocks at this igneous center consist of an older granodiorite pluton (the Mt Richthofen stock, MRS) that is intruded by the granitic Mt. Cumulus stock. The latter has a uniform bulk composition equivalent to that of high silica rhyolite (~77 wt % SiO2, ɛNd(T) ~ -6). Whole rock studies of the MRS reveal that it is compositionally zoned (55-67 wt % SiO2,ɛNd(T) -0.5 to -5.7, 87Sr/86Sr(T) 0.7049 to 0.7119), with the lowest wt % SiO2 and highest ɛNd(T) occurring along the western margin of the pluton. Field observations, combined with the observed compositional variations, suggest that the pluton was originally a shallowly intruded (< 2 km), ~1 km thick sill that was vertically zoned from a mafic base to more felsic roof. The entire pluton has been tilted ~25 degrees to the west after emplacement. Given the lack of obvious wall-rock assimilation at the level of pluton emplacement, the isotopic variations in the pluton most likely reflect differences in the isotopic compositions of melts from which the pluton was assembled. Obvious field evidence exists for underplating of the developing pluton by mafic, high ɛNd (T) (>-2) melts and illustrates that mafic magmas were present in the uppermost crust and likely participated in pluton formation. The higher wt % SiO2 and lower ɛNd(T) portions of the MRS, however, could not have been derived directly from the mafic magmas in any closed system process. One option is that the MRS ultimately represents the product of mixing of >70 wt % SiO2 melts (+ crystals), analogous to the melts from which the Mt. Cumulus stock crystallized, and underplating mafic magma. This model implies that two primary magmas types, high silica rhyolite and basalt/basaltic andesite

  2. Diel cycling of zinc in a stream impacted by acid rock drainage: Initial results from a new in situ Zn analyzer

    USGS Publications Warehouse

    Chapin, T.P.; Nimick, D.A.; Gammons, C.H.; Wanty, R.B.

    2007-01-01

    Recent work has demonstrated that many trace metals undergo dramatic diel (24-h) cycles in near neutral pH streams with metal concentrations reproducibly changing up to 500% during the diel period (Nimick et al., 2003). To examine diel zinc cycles in streams affected by acid rock drainage, we have developed a novel instrument, the Zn-DigiScan, to continuously monitor in situ zinc concentrations in near real-time. Initial results from a 3-day deployment at Fisher Creek, Montana have demonstrated the ability of the Zn-DigiScan to record diel Zn cycling at levels below 100 ??g/l. Longer deployments of this instrument could be used to examine the effects of episodic events such as rainstorms and snowmelt pulses on zinc loading in streams affected by acid rock drainage. ?? Springer Science+Business Media B.V. 2006.

  3. The role of igneous and metamorphic processes in triggering mass extinctions and Earth crises

    NASA Astrophysics Data System (ADS)

    Svensen, Henrik; Planke, Sverre; Polozov, Alexander G.; Jerram, Dougal; Jones, Morgan T.

    2016-04-01

    Mass extinctions and transient climate events commonly coincide in time with the formation of Large igneous provinces (LIPs). The end-Permian event coincides with the Siberian Traps, the end-Triassic with the Central Atlantic Magmatic Event (CAMP), the Toarcian with the Karoo LIP, and the Paleocene-Eocene Thermal Maximum (PETM) with the North Atlantic Igneous Province. Although the temporal relationship between volcanism and the environmental crises has been known for decades, the geological processes linking LIPs to these environmental events are strongly debated: Explosive LIP volcanism should lead to short term cooling (not long term warming), mantle CO2 is too 13C-enriched to explain negative 13C carbon isotope excursions from sedimentary sequences, the LIP volcanism is poorly dated and apparently lasts much longer that the associated environmental events, large portions of the LIPs remain poorly explored, especially the sub-volcanic parts where sills and dikes are emplaced in sedimentary host rocks, and thus gas flux estimates from contact aureoles around sill intrusions are often poorly constrained. In this presentation, we discuss the status of LIP research with an emphasis on the sub volcanic processes. We show that potential for degassing of greenhouse gases, aerosols, and ozone destructive gases is substantial and can likely explain the triggering of both climatic events and mass extinctions.

  4. Performance of an open limestone channel for treating a stream affected by acid rock drainage (León, Spain).

    PubMed

    Santofimia, Esther; López-Pamo, Enrique

    2016-07-01

    The generation of acid rock drainage (ARD) was observed after the oxidation dissolution of pyrite-rich black shales, which were excavated during the construction of a highway in León (Spain). ARDs are characterized by the presence of high concentrations of sulfate and metals (Al, Fe, Mn, Zn, Cu, Co, Ni, Th, and U) that affect the La Silva stream. Dissolved element concentrations showed values between one and four orders of magnitude higher than those of natural waters of this area. A passive treatment system was constructed; the aim of which was to improve the quality of the water of the stream. This work provides a hydrochemical characterization of the La Silva stream after its transit through the different elements that constitute the passive treatment system (open limestone channel (OLC), small ponds, and a wetland), during its first year of operation. The passive treatment system has two sections separated by a tunnel 230 m long. The first section, which stretches between the highway and the tunnel entrance, is an OLC 350 m long with a slope of 16 %. The second section, which stretches from the tunnel exit to the end wetland, has a length of 700 m and a slope of 6 %; it is in this section where six small ponds are located. In the first section of this passive treatment system, the OLC was effectively increasing the pH from 3 to 4-4.5 and eliminating all of the dissolved Fe and the partially dissolved Al. These elements, after hydrolysis at a pH 3-3.5 and 4-4.5, respectively, had precipitated as schwertmannite and hydrobasaluminite, while other dissolved metals were removed totally or partially for adsorption by the precipitates and/or by coprecipitation. The second section receives different inputs of water such as ARDs and natural waters. After exiting the treatment system, the stream is buffered by Al at a pH of 4-4.3, showing high Al concentrations (19-101 mg/L) but with a complete removal of dissolved Fe. Unfortunately, the outflow shows similar or

  5. Apollo 16 rocks - Petrology and classification.

    NASA Technical Reports Server (NTRS)

    Wilshire, H. G.; Stuart-Alexander, D. E.; Jackson, E. D.

    1973-01-01

    The Apollo 16 rocks are classified in three broad intergradational groups: (1) crystalline rocks, subdivided into igneous rocks and metaclastic rocks, (2) glass, and (3) breccias, which are subdivided into five groups on the basis of clast and matrix colors. Most of the rocks were derived by impact brecciation of an anorthosite-norite suite but may represent ejecta from more than one major basin. First-cycle breccias are believed to have consisted of clasts of crushed anorthosite-norite in a fine-grained partly fused matrix with a chemical composition similar to that of the clasts. Most of the other recognized breccia types could have been produced by rebrecciation of first-cycle breccias.

  6. Calcic myrmekite in anorthositic and gabbroic rocks

    SciTech Connect

    Schiffries, C.M.; Dymek, R.F.

    1985-01-01

    Myrmekite is a common feature of granitic plutonic rocks and quartzo-feldspathic gneisses, but it is rarely reported in anorthositic and gabbroic rocks. The authors have identified myrmekitic intergrowths of quartz and calcic plagioclase in a variety of plagioclase-rich cumulate rocks, including samples from a number of massif anorthosites and layered igneous intrusions. It appears that calcic myrmekite has been frequently overlooked, and is a common accessory feature in these rock types. Chemical and textural characteristics of myrmekite in the St-Urbain massif anorthosite (Quebec) and the Bushveld Igneous Complex (South Africa) have several features in common, but this myrmekite appears to be fundamentally different from that described by most previous investigators. Whereas myrmekite typically consists of a vermicular intergrowth of sodic plagioclase and quartz that occurs adjacent to alkali feldspar, the intergrowths in these rocks contain highly calcic plagioclase and lack the intervening alkali feldspar. In addition, the plagioclase in the myrmekite is more calcic than that in the surrounding rock. The boundary between the myrmekite and the host material is generally extremely sharp, although reverse zoning of host plagioclase may obscure the contact in some cases. The textural and chemical evidence is consistent with a replacement origin for these intergrowths; the proportion of quartz in the myrmekite is in close agreement with the predicted amount of silica that is generated by the theoretical replacement reaction. It appears that water played a key role in the replacement process.

  7. In Situ Geophysical Surveys for Estimation of Foundation Rock Properties, Concrete Gravity Section, Folsom Dam

    DTIC Science & Technology

    2005-08-01

    underlain by igneous rock, which ranges from granodiorite to quartz diorite. The rock is medium gray in color and medium to coarse grained. The...the hole, which was assumed to represent a moderately weathered/fractured granodiorite /granite. Based on the above information, a value of 14,000 fps

  8. Origin of igneous meteorites and differentiated asteroids

    NASA Astrophysics Data System (ADS)

    Scott, E.; Goldstein, J.; Asphaug, E.; Bottke, W.; Moskovitz, N.; Keil, K.

    2014-07-01

    Introduction: Igneously formed meteorites and asteroids provide major challenges to our understanding of the formation and evolution of the asteroid belt. The numbers and types of differentiated meteorites and non-chondritic asteroids appear to be incompatible with an origin by fragmentation of numerous Vesta-like bodies by hypervelocity impacts in the asteroid belt over 4 Gyr. We lack asteroids and achondrites from the olivine-rich mantles of the parent bodies of the 12 groups of iron meteorites and the ˜70 ungrouped irons, the 2 groups of pallasites and the 4--6 ungrouped pallasites. We lack mantle and core samples from the parent asteroids of the basaltic achondrites that do not come from Vesta, viz., angrites and the ungrouped eucrites like NWA 011 and Ibitira. How could core samples have been extracted from numerous differentiated bodies when Vesta's basaltic crust was preserved? Where is the missing Psyche family of differentiated asteroids including the complementary mantle and crustal asteroids [1]? Why are meteorites derived from far more differentiated parent bodies than chondritic parent bodies even though C and S class chondritic asteroids dominate the asteroid belt? New paradigm. Our studies of meteorites, impact modeling, and dynamical studies suggest a new paradigm in which differentiated asteroids accreted at 1--2 au less than 2 Myr after CAI formation [2]. They were rapidly melted by 26Al and disrupted by hit-and-run impacts [3] while still molten or semi-molten when planetary embryos were accreting. Metallic Fe-Ni bodies derived from core material cooled rapidly with little or no silicate insulation less than 4 Myr after CAI formation [4]. Fragments of differentiated planetesimals were subsequently tossed into the asteroid belt. Meteorite evidence for early disruption of differentiated asteroids. If iron meteorites were samples of Fe-Ni cores of bodies that cooled slowly inside silicate mantles over ˜50--100 Myr, irons from each core would have

  9. A discussion of isotopic systematics and mineral zoning in the shergottites - Evidence for a 180 m.y. igneous crystallization age

    NASA Technical Reports Server (NTRS)

    Jones, J. H.

    1986-01-01

    The chronologies of the Shergotty, Zagami, ALHA 77005, and EETA 79001 meteorites were reexamined on the basis of shergottites' petrography and mineral chemistry data. Among the various isochrons, the concordant Rb-Sr (about 180 Myr) and U-Th-Pb (about 190 Myr) internal isochrons are interpreted as representing the time of igneous crystallization, while the Rb-Sr, Sm-Nd, and Pb-Pb whole-rock isochrons are interpreted as mixing lines, and are reasonably attributed to igneous processes such as wall-rock assimilation and magma mixing. If the approximated age of less than 200 Myr is correct, the shergottites represent the youngest known extraterrestrial basalts. This conclusion supports the hypothesis that the SNC meteorites are samples of Mars.

  10. Experiments and Spectral Studies of Martian Volcanic Rocks: Implications for the Origin of Pathfinder Rocks and Soils

    NASA Technical Reports Server (NTRS)

    Rutherford, Malcolm J.; Mustard, Jack; Weitz, Catherine

    2002-01-01

    The composition and spectral properties of the Mars Pathfinder rocks and soils together with the identification of basaltic and andesitic Mars terrains based on Thermal Emission Spectrometer (TES) data raised interesting questions regarding the nature and origin of Mars surface rocks. We have investigated the following questions: (1) are the Pathfinder rocks igneous and is it possible these rocks could have formed by known igneous processes, such as equilibrium or fractional crystallization, operating within SNC magmas known to exist on Mars? If it is possible, what P (depth) and PH2O conditions are required? (2) whether TES-based interpretations of plagioclase-rich basalt and andesitic terrains in the south and north regions of Mars respectively are unique. Are the surface compositions of these regions plagioclase-rich, possibly indicating the presence of old AI-rich crust of Mars, or are the spectra being affected by something like surface weathering processes that might determine the spectral pyroxene to plagioclase ratio?

  11. Brushed Target on Rock 'Champagne' in Gusev Crater

    NASA Technical Reports Server (NTRS)

    2005-01-01

    NASA's Mars Exploration Rover Spirit took this microscopic image of a target called 'Bubbles' on a rock called 'Champagne' after using its rock abrasion tool to brush away a coating of dust. The circular brushed area is about 5 centimeters (2 inches) across. This rock is different from rocks out on the plains of Gusev Crater but is similar to other rocks in this area of the 'Columbia Hills' in that it has higher levels of phosphorus. Plagioclase, a mineral commonly found in igneous rocks, is also present in these rocks, according to analysis with the minature thermal emission spectrometer. By using the alpha particle X-ray spectrometer to collect data over multiple martian days, or sols, scientists are also beginning to get measurements of trace elements in these rocks. Spirit took the images that are combined into this mosaic on sol 354 (Dec. 30, 2004).

  12. Source rock maturation, San Juan sag

    SciTech Connect

    Gries, R.R.; Clayton, J.L.

    1989-09-01

    Kinetic modeling for thermal histories was simulated for seven wells in the San Juan sag honoring measured geochemical data. Wells in the area of Del Norte field (Sec. 9, T40N, R5E), where minor production has been established from an igneous sill reservoir, show that the Mancos Shale source rocks are in the mature oil generation window as a combined result of high regional heat flow and burial by approximately 2,700 m of Oligocene volcanic rocks. Maturation was relatively recent for this area and insignificant during Laramide subsidence. In the vicinity of Gramps field (Sec. 24, T33N, R2E) on the southwest flank of the San Juan sag, these same source rocks are exposed due to erosion of the volcanic cover but appear to have undergone a similar maturation history. At the north and south margins of the sag, two wells (Champlin 34A-13, Sec. 13, T35N, R4.5E; and Champlin 24A-1, Sec. 1, T44N, R5E) were analyzed and revealed that although the regional heat flow was probably similar to other wells, the depth of burial was insufficient to cause maturation (except where intruded by thick igneous sills that caused localized maturation). The Meridian Oil 23-17 South Fork well (Sec. 17, T39N, R4E) was drilled in a deeper part of the San Juan sag, and source rocks were intruded by numerous igneous sills creating a complex maturation history that includes overmature rocks in the lowermost Mancos Shale, possible CO{sub 2} generation from the calcareous Niobrara Member of the Mancos Shale, and mature source rocks in the upper Mancos Shale.

  13. Paleomagnetic directional groups and paleointensity from the flood basalt in the Tarim large igneous province: implications for eruption frequency

    NASA Astrophysics Data System (ADS)

    Usui, Yoichi; Tian, Wei

    2017-01-01

    We present paleomagnetic secular variation and paleointensity from the Early Permian Tarim large igneous province, NW China. The studied sections comprise a total of 400 m of basaltic flows. Paleomagnetic directions were determined for 11 flows. Four successive flows with a cumulative thickness of 150 m showed a statistically identical paleomagnetic direction. Assuming a paleosecular variation speed similar to that of the present day, the 150-m-thick basalt was estimated to have erupted within the past few centuries. Paleointensity experiments were performed on both whole-rock and single plagioclase samples. Although alterations during the experiment and/or weak remanence degraded the data quality, the flows with the same paleomagnetic direction revealed similar paleointensity estimates, supporting the hypothesis that the eruption of these flows was rapid. More generally, flows from the Lower Kupukuziman Formation seem to record lower paleointensity compared to flows from the overlying Kaipaizileike Formation. [Figure not available: see fulltext. Caption: Left the extent of the Tarim large igneous province. Center in-situ paleomagnetic directions obtained from the Tarim large igneous province. Subashi and Yingan represents directions reported in a previous research. Right tilt-corrected paleomagnetic directions. Tight clustering of the direction indicate fast eruption relative to the paleomagnetic secular variation (PSV) speed.

  14. Pollack Crater's White Rock

    NASA Technical Reports Server (NTRS)

    2008-01-01

    has a higher spatial resolution that enables CRISM to see smaller exposures of these minerals, if they occur. If White Rock is an evaporative lacustrine or lake deposit, CRISM has the best chance of detecting telltale mineralogical signatures. The images above reveal what CRISM found.

    The top panel in the montage above shows the location of the CRISM image on a mosaic of Pollack Crater taken by the Mars Odyssey spacecraft's Thermal Emission Imaging System (THEMIS). White Rock actually appears dark in the THEMIS mosaic due to a low daytime temperature, because its light color leads to less heating by the Sun. The middle-left image is an infrared, false color image that reveals White Rock's reddish hue. The middle-right image shows the signatures of different minerals that are present. CRISM found that White Rock is composed of accumulated dust perhaps with some fine-grained olivine (an igneous mineral), surrounded by basaltic sand containing olivine and dark-colored pyroxene. The lower two images were constructed by draping CRISM images over topography and exaggerating the vertical scale to better illustrate White Rock's topography. White Rock still appears not to contain evaporite, but instead to be composed of accumulated dust and sand.

    CRISM is one of six science instruments on NASA's Mars Reconnaissance Orbiter. Led by The Johns Hopkins University Applied Physics Laboratory, Laurel, Md., the CRISM team includes expertise from universities, government agencies and small businesses in the United States and abroad. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter and the Mars Science Laboratory for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, built the orbiter.

  15. Building the EarthChem System for Advanced Data Management in Igneous Geochemistry

    NASA Astrophysics Data System (ADS)

    Lehnert, K.; Walker, J. D.; Carlson, R. W.; Hofmann, A. W.; Sarbas, B.

    2004-12-01

    Several mature databases of geochemical analyses for igneous rocks are now available over the Internet. The existence of these databases has revolutionized access to data for researchers and students allowing them to extract data sets customized to their specific problem from global data compilations with their desktop computer within a few minutes. Three of the database efforts - PetDB, GEOROC, and NAVDAT - have initiated a collaborative effort called EarthChem to create better and more advanced and integrated data management for igneous geochemistry. The EarthChem web site (http://www.earthchem.org/) serves as a portal to the three databases and information related to EarthChem activities. EarthChem participants agreed to establish a dialog to minimize duplication of effort and share useful tools and approaches. To initiate this dialog, a workshop was run by EarthChem in October, 2003 to discuss cyberinfrastructure needs in igneous geochemistry (workshop report available at the EarthChem site). EarthChem ran an information booth with database and visualization demonstrations at the Fall 2003 AGU meeting (and will have one in 2004) and participated in the May 2003 GERM meeting in Lyon, France where we provided the newly established Publishers' Round Table a list of minimum standards of data reporting to ease the assimilation of data into the databases. Aspects of these suggestions already have been incorporated into new data policies at Geochimica et Cosmochimica Acta and Chemical Geology (Goldstein et al. 2004), and are under study by the Geological Society of America. EarthChem presented its objectives and activities to the Solid Earth Sciences community at the Annual GSA Meeting 2003 (Lehnert et al, 2003). Future plans for EarthChem include expanding the types and amounts of data available from a single portal, giving researchers, faculty, students, and the general public the ability to search, visualize, and download geochemical and geochronological data for a

  16. The Paleoproterozoic Singo granite in south-central Uganda revealed as a nested igneous ring complex using geophysical data

    NASA Astrophysics Data System (ADS)

    Abdelsalam, Mohamed G.; Katumwehe, Andrew B.; Atekwana, Estella A.; Le Pera, Alan K.; Achang, Mercy

    2016-04-01

    We used high-resolution airborne magnetic and radiometric data and satellite gravity data to investigate the form of occurrence of the Paleoproterozoic Singo granite in west-central Uganda. This granitic body covers an area of ∼700 km2, intrudes Paleoproterozoic crystalline rocks and overlain by Paleoproterozoic-Mesoproterozoic sedimentary rocks, both of which belong to the Rwenzori terrane, and it is host to hydrothermally-formed economic minerals such as gold and tungsten. Our analysis provided unprecedented geometrical details of the granitic body and revealed the following: (1) the margins of the Singo granite are characterized by a higher magnetic signature compared to the interior of the granitic body as well as the surroundings. These anomalies are apparent in both the total magnetic field and horizontal derivative images and define eight overlapping ring features. (2) the depth continuation of these magnetic anomalies define outward but steeply-dipping features as indicated by the tilt images extracted from the airborne magnetic data. This is further supported by forward modeling of the magnetic and gravity data. (3) the Singo granite is characterized by relatively high and evenly-distributed equivalent concentration of Uranium (eU) and Thorium (eTh) compared to the surroundings and this is apparent in the Potassium (K)-eTh-eU radiometric ternary image. (4) the granitic body is defined by a gravity low anomaly that persisted to a depth of three km as shown by the Bouguer anomaly image and its five km upward continuation. We used these observations to identify this granitic body as a nested igneous ring complex and we refer to it as the Singo Igneous Ring Complex (SIRC). We further interpreted the eight ring structures as individual igneous ring complexes aligned in an E-W and NE-SW direction and these were developed due to repeated calderas collapse. Additionally, we interpreted the ring-shaped magnetic anomalies as due to hydrothermally-altered margins

  17. The Formation of Igneous CAIs and Chondrules by Impacts?

    NASA Technical Reports Server (NTRS)

    Connolly, Harold C., Jr.; Love, Stanley G.

    2001-01-01

    Numerous challenges exist with forming the igneous spheres found within chondrites via collision events in the early solar nebula. We explore these challenges and discuss potential methods to overcome them. Collision models should be received cautiously. Additional information is contained in the original extended abstract.

  18. Igneous fractionation and subsolidus equilibration of diogenite meteorites

    NASA Technical Reports Server (NTRS)

    Mittlefehldt, David W.

    1993-01-01

    Diogenites are coarse-grained orthopyroxenite breccias of remarkably uniform major element composition. Most diogenites contain homogeneous pyroxene fragments up to 5 cm across of Wo2En74Fs24 composition. Common minor constituents are chromite, olivine, trolite and metal, while silica, plagioclase, merrillite and diopside are trace phases. Diogenites are generally believed to be cumulates from the eucrite parent body, although their relationship with eucrites remains obscure. It has been suggested that some diogenites are residues after partial melting. I have performed EMPA and INAA for major, minor and trace elements on most diogenites, concentrating on coarse-grained mineral and lithic clasts in order to elucidate their igneous formation and subsequent metamorphic history. Major element compositions of diogenites are decoupled from minor and trace element compositions; the latter record an igneous fractionation sequence that is not preserved in the former. Low equilibration temperatures indicate that major element diffusion continued long after crystallization. Diffusion coefficients for trivalent and tetravalent elements in pyroxene are lower than those of divalent elements. Therefore, major element compositions of diogenites may represent means of unknown portions of a cumulate homogenized by diffusion, while minor and trace elements still yield information on their igneous history. The scale of major element equilibration is unknown, but is likely to be on the order of a few cm. Therefore, the diogenite precursors may have consisted largely of cm-sized, igneously zoned orthopyroxene grains, which were subsequently annealed during slow cooling, obliterating major element zoning but preserving minor and trace incompatible element zoning.

  19. The Central-Western Mediterranean: Anomalous igneous activity in an anomalous collisional tectonic setting

    NASA Astrophysics Data System (ADS)

    Lustrino, Michele; Duggen, Svend; Rosenberg, Claudio L.

    2011-01-01

    The central-western Mediterranean area is a key region for understanding the complex interaction between igneous activity and tectonics. In this review, the specific geochemical character of several 'subduction-related' Cenozoic igneous provinces are described with a view to identifying the processes responsible for the modifications of their sources. Different petrogenetic models are reviewed in the light of competing geological and geodynamic scenarios proposed in the literature. Plutonic rocks occur almost exclusively in the Eocene-Oligocene Periadriatic Province of the Alps while relatively minor plutonic bodies (mostly Miocene in age) crop out in N Morocco, S Spain and N Algeria. Igneous activity is otherwise confined to lava flows and dykes accompanied by relatively greater volumes of pyroclastic (often ignimbritic) products. Overall, the igneous activity spanned a wide temporal range, from middle Eocene (such as the Periadriatic Province) to the present (as in the Neapolitan of southern Italy). The magmatic products are mostly SiO 2-oversaturated, showing calcalkaline to high-K calcalcaline affinity, except in some areas (as in peninsular Italy) where potassic to ultrapotassic compositions prevail. The ultrapotassic magmas (which include leucitites to leucite-phonolites) are dominantly SiO 2-undersaturated, although rare, SiO 2-saturated (i.e., leucite-free lamproites) appear over much of this region, examples being in the Betics (southeast Spain), the northwest Alps, northeast Corsica (France), Tuscany (northwest Italy), southeast Tyrrhenian Sea (Cornacya Seamount) and possibly in the Tell region (northeast Algeria). Excepted for the Alpine case, subduction-related igneous activity is strictly linked to the formation of the Mediterranean Sea. This Sea, at least in its central and western sectors, is made up of several young (< 30 Ma) V-shaped back-arc basins plus several dispersed continental fragments, originally in crustal continuity with the European

  20. Igneous Petrogenesis of Tequila Volcano, Western Mexico

    NASA Astrophysics Data System (ADS)

    Vázquez-Duarte, A.; Gómez-Tuena, A.; Díaz-Bravo, B.

    2011-12-01

    Tequila volcano belongs to a Quaternary volcanic chain that runs in parallel to the Middle American Trench, but that have been constructed within the so-called Tepic-Zacoalco rift: an extensional tectonic structure that has been active for the past 3.5 Ma. This unusual tectonic setting, and the existence of a high-resolution stratigraphy for the Tequila Volcanic Field (Lewis-Kenedi, 2005, Bull Volcanol), provide an excellent opportunity to study andesite petrogenesis. New comprehensive geochemical data allow the recognition of at least four different magmatic series around Tequila: 1) The Santa Rosa intraplate basalts (1.0 - 0.2 Ma), a volcanic plateau constructed along the Santiago River Fault north of Tequila volcano. These Na-alkaline basalts are olivine-phyric, have negligible subduction signatures (Ba/Nb= 11.75 - 49.36), and display Sr-Nd-Pb isotopic compositions that correlate with fractionation indexes, probably indicating melt-crust interactions. 2) A group of vitreous domes and flows of dacitic to rhyolitic compositions, mostly contemporaneous to the Santa Rosa basalts, that were emplaced on the periphery of Tequila volcano. These rocks can have very low Sr and Eu contents but their isotopic compositions are remarkably constant and similar to the Santa Rosa basalts, probably indicating a genetic link through low pressure fractionation in the stability field of plagioclase. 3) The main edifice of Tequila volcano (~0.2 Ma) is made of two pyroxene andesites and dacites with strong subduction signatures (Ba/Nb= 53-112), that inversely correlate with MgO contents, but that follow a diverging evolutionary trend as the rest of the sequences. The isotopic compositions of Tequila main edifice can extend to slightly more enriched values, but do not correlate with fractionation indexes, thus indicating provenance from a different source. 4) The youngest activity on Tequila volcano (~0.09 Ma) is represented by amphibole bearing andesites that erupted through the

  1. A chemical model for lunar non-mare rocks

    NASA Technical Reports Server (NTRS)

    Hubbard, N. J.; Rhodes, J. M.

    1974-01-01

    Nearly all rocks returned from the moon are readily divided into three broad categories on the basis of their chemical compositions: (1) mare basalts, (2) non-mare rocks of basaltic composition (KREEP, VHA), and (3) anorthositic rocks. Only mare basalts may unambiguously be considered to have original igneous textures and are widely understood to have an igneous origin. Nearly all other lunar rocks have lost their original textures during metamorphic and impact processes. It is shown that for these rocks one must work primarily with chemical data in order to recognize and define rock groups and their possible modes of origin. Non-mare rocks of basaltic composition have chemical compositions consistent with an origin by partial melting of the lunar interior. The simplest origin for rocks of anorthositic chemical composition is the crystallization and removal of ferromagnesian minerals. It is proposed that the rock groups of anorthositic and non-mare basaltic chemical composition could have been generated from a single series of original but not necessarily primitive lunar materials.

  2. A chemical model for lunar non-mare rocks

    NASA Technical Reports Server (NTRS)

    Hubbard, N. J.; Rhodes, J. M.

    1977-01-01

    Nearly all rocks returned from the moon are readily divided into three broad categories on the basis of their chemical compositions: (1) mare basalts, (2) non-mare rocks of basaltic composition (KREEP, VHA), and (3) anorthositic rocks. Only mare basalts may unambiguously be considered to have original igneous textures and are widely understood to have an igneous origin. Nearly all other lunar rocks have lost their original textures during metamorphic and impact processes. For these rocks one must work primarily with chemical data in order to recognize and define rock groups and their possible modes of origin. Non-mare rocks of basaltic composition have chemical compositions consistent with an origin by partial melting of the lunar interior. The simplest origin for rocks of anorthositic chemical composition is the crystallization and removal of ferromagnesian minerals. It is proposed that the rock groups of anorthositic and non-mare basaltic chemical composition could have been generated from a single series of original, but not necessarily primitive, lunar materials.

  3. Kilbuck terrane: Oldest known rocks in Alaska

    SciTech Connect

    Box, S.E. ); Moll-Stalcup, E.J.; Wooden, J.L. ); Bradshaw, J.Y. )

    1990-12-01

    The Kilbuck terrane in southwestern Alaska is a narrow, thin crustal sliver or flake of amphibolite facies orthogneiss. The igneous protolith of this gneiss was a suite of subduction-related plutonic rocks. U-Pb data on zircons from trondhjemitic and granitic samples yield upper-intercept (igneous) ages of 2,070 {plus minus}16 and 2,040 {plus minus}74 Ma, respectively. Nd isotope data from these rocks suggest that a diorite-tonalite-trondhjemite suite ({epsilon}{sub Nd}(T) = +2.1 to +2.7; T is time of crystallization) evolved from partial melts of depleted mantle with no discernible contamination by older crust, whereas a coeval granitic pluton ({epsilon}{sub Nd}(T) = {minus}5.7) contains a significant component derived from Archean crust. Orthogneisses with similar age and Nd isotope characteristics are found in the Idono complex 250 km to the north. Early Proterozoic rocks are unknown elsewhere in Alaska. However, Phanerozoic plutons cutting several continental terranes in Alaska (southern Brooks Range and Ruby, Seward, and Yukon-Tanana terranes) have Nd isotope compositions indicative of Early Proterozoic (or older) crustal components that could be correlative with rocks of the Kilbuck terrane. Rocks with similar igneous ages in cratonal North America are rare, and those few that are known have Nd isotope compositions distinct from those of the Kilbuck terrane. Conversely, provinces with Nd model ages of 2.0-2.1 Ga are characterized by extensive 1.8 Ga or younger plutonism, which is unknown in the Kilbuck terrane. At present the case for a North American parentage of the Kilbuck terrane is not compelling. The possibility that the Kilbuck terrane was displaced from provinces of similar age in other cratons (e.g., Australian, Baltic, Guiana, and west African shields), or from the poorly dated Siberian craton, cannot be excluded.

  4. Digitizing rocks standardizing the geological description process using workstations

    SciTech Connect

    Saunders, M.R. , Windsor, Berkshire ); Shields, J.A. ); Taylor, M.R. )

    1993-09-01

    The preservation of geological knowledge in a standardized digital form presents a challenge. Data sources, inherently fuzzy, range in scale from the macroscopic (e.g., outcrop) through the mesoscopic (e.g., hand-specimen) core and sidewall core, to the microscopic (e.g., drill cuttings, thin sections, and microfossils). Each scale change results in increased heterogeneity and potentially contradictory data and the providers of such data may vary in experience level. To address these issues with respect to cores and drill cuttings, a geological description workstation has been developed and is undergoing field trials. Over 1000 carefully defined geological attributes are currently available within a depth-indexed, relational database. Attributes are stored in digital form, allowing multiple users to select familiar usage (e.g., diabase vs. dolerite). Data can be entered in one language and retrieved in other languages. The database structure allow groupings of similar elements (e.g., rhyolites in acidic, igneous or volcanics subgroups or the igneous rock group) permitting different uses to analyze details appropriate to the scale of the usage. Data entry uses a graphical user interface, allowing the geologist to make quick, logical selections in a standardized or custom-built format with extensive menus, on-screen graphics and help screens available. Description ranges are permissible. Entries for lithology, petrology, structures (sedimentary, organic and deformational), reservoir characteristics (porosity and hydrocarbon shows), and macrofossils are available. Sampling points for thin sections, core analysis, geochemistry, or micropaleontology studies are also recorded. Using digital data storage, geological logs using graphical, alphanumeric and symbolic depictions are possible. Data can be integrated with drilling and mud gas data, MWD and wireline data and off well-site analyses to produced composite formation evaluation logs and interpretational crossplots.

  5. Hawai'i and Gale Crater: A Mars Analogue Study of Igneous, Sedimentary, Weathering, and Alteration Trends in Geochemistry

    NASA Technical Reports Server (NTRS)

    Berger, J. A.; Flemming, R. L.; Schmidt, M. E.; Gellert, R.; Morris, R. V.; Ming, D. W.

    2017-01-01

    Sedimentary rocks in Gale Crater on Mars indicate a varied provenance with a range of alteration and weathering [1, 2]. Geochemical trends identified in basaltic and alkalic sedimentary rocks by the Alpha Particle X-ray Spectrometer (APXS) on the Mars rover Curiosity represent a complex interplay of igneous, sedimentary, weathering, and alteration processes. Assessing the relative importance of these processes is challenging with unknown compositions for parent sediment sources and with the constraints provided by Curiosity's instruments. We therefore look to Mars analogues on Earth where higher-resolution analyses and geologic context can constrain interpretations of Gale Crater geochemical observations. We selected Maunakea (AKA Mauna Kea) and Kohala volcanoes, Hawai'i, for an analogue study because they are capped by post-shield transitional basalts and alkalic lavas (hawaiites, mugearites) with compositions similar to Gale Crater [1, 3]. Our aim was to characterize Hawaiian geochemical trends associated with igneous processes, sediment transport, weathering, and alteration. Here, we present initial results and discuss implications for selected trends observed by APXS in Gale Crater.

  6. Darkening of silicate rock powders by solar wind sputtering.

    NASA Technical Reports Server (NTRS)

    Hapke, B.

    1973-01-01

    Hydrogen ion irradiation of powdered igneous rocks, including Apollo rocks, has been observed in the laboratory to darken the powders and to make their optical properties similar to the moon's. An extensive series of investigations shows that this darkening is not spurious. These results are consistent with those of other investigators, including Nash (1967). Darkening of lunar igneous rock powders by the formation of solar wind-sputtered glass films is a real process which occurs on the moon. The time scale for darkening of undisturbed lunar soil is of the order of 50,000-100,000 yr. Comparison of the rates of the formation of glasses on the lunar surface by solar wind sputter-deposition, meteorite impact melting, and impact vaporization-deposition indicates that these processes are of comparable importance under the present flux of meteorites.

  7. Rock Finding

    ERIC Educational Resources Information Center

    Rommel-Esham, Katie; Constable, Susan D.

    2006-01-01

    In this article, the authors discuss a literature-based activity that helps students discover the importance of making detailed observations. In an inspiring children's classic book, "Everybody Needs a Rock" by Byrd Baylor (1974), the author invites readers to go "rock finding," laying out 10 rules for finding a "perfect" rock. In this way, the…

  8. Rock Art

    ERIC Educational Resources Information Center

    Henn, Cynthia A.

    2004-01-01

    There are many interpretations for the symbols that are seen in rock art, but no decoding key has ever been discovered. This article describes one classroom's experiences with a lesson on rock art--making their rock art and developing their own personal symbols. This lesson allowed for creativity, while giving an opportunity for integration…

  9. Science Rocks!

    ERIC Educational Resources Information Center

    Prestwich, Dorothy; Sumrall, Joseph; Chessin, Debby A.

    2010-01-01

    It all began one Monday morning. Raymond could not wait to come to large group. In his hand, he held a chunk of white granite he had found. "Look at my beautiful rock!" he cried. The rock was passed around and examined by each student. "I wonder how rocks are made?" wondered one student. "Where do they come from?"…

  10. 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.

  11. Thermal aureoles of igneous intrusions: some possible indications of hydrothermal convective cooling

    SciTech Connect

    Parmentier, E.M.; Schedl, A.

    1981-01-01

    The size and shape of metamorphic aureoles is investigated as a possible indicator of hydrothermal convective cooling of epizonal igneous intrusions. A simple family of numerical models illustrates the effect of convective cooling on maximum temperatures attained in the country rock surrounding an intrusion. Boundary layer approximations have also been applied to describe convection of vaporizing groundwater near the contact of an intrusion early in its cooling history. Maximum temperature isotherms are taken to reflect the width and shape of thermal aureoles defined by preserved mineral assemblages as appears to be reasonable based on several well-studied conductively cooled intrusions. The thermal aureoles of intrusions for which oxygen and hydrogen isotope data indicate convective groundwater circulation have been examined on the basis of the simple numerical and boundary layer models. The shape of the low temperature alteration aureole of the well-mapped El Salvador porphyry copper deposit suggests convective cooling of a permeable intrusion. The width of the low temperature (greenschist) aureole of the Mull intrusive complex can be explained by convective cooling of permeable intrusive rock. The narrow high temperature (amphibolite) aureole of the Cuillin gabbro on Skye can be explained by strong convective cooling; but the low temperature (greenschist) aureole is wide enough to be consistent with conductive cooling, thus suggesting decreasing permeabilities during the cooling history. This is consistent with oxygen isotope sampling and other geologic observations.

  12. The High Arctic Large Igneous Province Mantle Plume caused uplift of Arctic Canada

    NASA Astrophysics Data System (ADS)

    Galloway, Jennifer; Ernst, Richard; Hadlari, Thomas

    2016-04-01

    The Sverdrup Basin is an east-west-trending extensional sedimentary basin underlying the northern Canadian Arctic Archipelago. The tectonic history of the basin began with Carboniferous-Early Permian rifting followed by thermal subsidence with minor tectonism. Tectonic activity rejuvenated in the Hauterivian-Aptian by renewed rifting and extension. Strata were deformed by diapiric structures that developed during episodic flow of Carboniferous evaporites during the Mesozoic and the basin contains igneous components associated with the High Arctic Large Igneous Province (HALIP). HALIP was a widespread event emplaced in multiple pulses spanning ca. 180 to 80 Ma, with igneous rocks on Svalbard, Franz Josef Island, New Siberian Islands, and also in the Sverdrup Basin on Ellef Ringnes, Axel Heiberg, and Ellesmere islands. Broadly contemporaneous igneous activity across this broad Arctic region along with a reconstructed giant radiating dyke swarm suggests that HALIP is a manifestation of large mantle plume activity probably centred near the Alpha Ridge. Significant surface uplift associated with the rise of a mantle plume is predicted to start ~10-20 my prior to the generation of flood basalt magmatism and to vary in shape and size subsequently throughout the LIP event (1,2,3) Initial uplift is due to dynamical support associated with the top of the ascending plume reaching a depth of about 1000 km, and with continued ascent the uplift topography broadens. Additional effects (erosion of the ductile lithosphere and thermal expansion caused by longer-term heating of the mechanical lithosphere) also affect the shape of the uplift. Topographic uplift can be between 1 to 4 km depending on various factors and may be followed by subsidence as the plume head decays or become permanent due to magmatic underplating. In the High Arctic, field and geochronological data from HALIP relevant to the timing of uplift, deformation, and volcanism are few. Here we present new evidence

  13. Igneous Crystallization Beginning at 20 km Beneath the Mid-Atlantic Ridge, 14 to 16 N

    NASA Astrophysics Data System (ADS)

    Kelemen, P.

    2003-12-01

    ODP Leg 209 drilled 19 holes at 8 sites along the Mid-Atlantic Ridge from 14° 43 to 15° 44 N. All sites were previously surveyed by submersible, and were chosen to be < 200 m from peridotite or dunite exposed on the seafloor; outcrops of gabbroic rock were also near some sites. One primary goal of Leg 209 was to constrain melt migration and igneous petrogenesis in this region where residual peridotites are exposed on both sides of the Ridge axis. At Sites 1269 and 1273, we penetrated 112 m of basaltic rubble; recovery was poor (3.7 m) and holes unstable, so drilling was terminated. Lavas form nearly horizontal surfaces overlying cliffs exposing peridotite and gabbro. At 6 other sites, we drilled a mixture of residual peridotite and gabbroic rocks intrusive into peridotite. We penetrated 1075 meters at these 6 sites, and recovered 354 m of core. Drilling at Sites 1268, 1270, 1271 and 1272 recovered 25% gabbroic rocks and 75% residual mantle peridotite. Core from Site 1274 is mainly residual peridotite, with a few m-scale gabbroic intrusions. Core from Site 1275 is mainly gabbroic, but contains 24% poikilitic lherzolite interpreted as residual peridotite "impregnated" by plagioclase and pyroxene crystallized from melt migrating along olivine grain boundaries; these impregnated peridotites were later intruded by evolved gabbros. Impregnated peridotites are also common at Site 1271, and present at Sites 1268 and 1270. The overall proportion of gabbroic rocks versus residual peridotites from these 6 sites is similar to previous dredging and submersible sampling in the area. The proportion of gabbro is larger than in"amagmatic" regions on the ultra-slow spreading SWIR and Gakkel Ridges. Impregnated peridotites from Site 1275 have "equilibrated" textures and contain olivine, 2 pyroxenes, plag and Cr-rich spinel. Their whole rock Mg#, Cr# and Ni are high, extending to residual peridotite values. 87 MORB glasses from 14 to 16° N with Mg# from 60 to 73 [from PetDB] could

  14. The mineralogy of global magnetic anomalies. [rock magnetic signatures and MAGSAT geological, and gravity correlations in West Africa

    NASA Technical Reports Server (NTRS)

    Haggerty, S. E. (Principal Investigator)

    1982-01-01

    Problems with the Curie balance, which severely hindered the acquisition of data, were rectified. Chemical analytical activities are proceeding satisfactorily. The magnetization characteristics of metamorphic suites were analyzed and susceptibility data for a wide range of metamorphic and igneous rocks. These rock magnetic signatures are discussed as well as the relationships between geology, gravity and MAGSAT anomalies of West Africa.

  15. Fixed Hot-spots Gone With Wind? Clues From Paleomagnetic Investigations of Large Igneous Provinces

    NASA Astrophysics Data System (ADS)

    Zhao, X.; Ernesto, M.

    2013-05-01

    Paleomagnetic studies of Ocean Drilling Program (ODP) 197 on samples from the Emperor-Hawaiian seamount chain suggested that these rocks formed much farther north than the hotspot currently beneath Hawaii. These findings indicate that the hotspot, once thought to be fixed beneath the Earth's crust, actually jumped southward rapidly. Here we report paleomagnetic evidence that is consistence with these findings and suggests that rapid hotspots motion (also southward jumps) occurred while the massive Ontong Java (OJP), Kerguelen Plateau (KP), and Parana Magmatic Province (PMP) large igneous provinces formed. The paleomagnetic paleolatitude for the OJP is ~20 farther north than those predicted by the Louisville hotspot model. The difference between the paleomagnetic and hotspot calculated paleolatitudes cannot be explained by true polar wander estimates derived from other lithospheric plates. Our results are therefore consistent with and extend the Emperor-Hawaiian hotspot features in the northern Pacific Ocean that suggest Late Cretaceous to Eocene motion of Pacific hotspots. Compared to the latitude of the Kerguelen hotspot, the paleolatitudes of the central and northern Kerguelen Plateau obtained by ODP Leg 183 are further north. This difference also indicates a southward movement of the Kerguelen hotspot since the Cretaceous relative to the spin axis of the Earth. Numerical modeling of plume conduit motion in a large-scale mantle flow also predicts southward motion of the Kerguelen hotspot, which is consistent with paleomagnetic results. Likewise, paleomagnetic results from PMP reveal significant southward movement of the Tristan da Cunha hotspot in the Cretaceous. Elucidating how large igneous province formation and mantle dynamics are related and whether hotspots moved at comparable rates during other times are challenges for future research.

  16. Igneous Consequence Modeling for the TSPA-SR

    SciTech Connect

    John McCord

    2001-10-29

    The purpose of this technical report is to develop credible, defendable, substantiated models for the consequences of igneous activity for the TSPA-SR Model. The effort will build on the TSPA-VA and improve the quality of scenarios and depth of the technical basis underlying disruptive events modeling. Computational models for both volcanic eruptive releases (this is an event that results in ash containing waste being ejected from Yucca Mountain) and igneous intrusion groundwater releases (this is an event that reaches the repository level, impacts the waste packages, and produces releases from waste packages damaged by igneous activity) will be included directly in the TSPA calculations as part of the TSPA-SR Model. This Analysis Model Report (AMR) is limited to development of the conceptual models for these two scenarios. The mathematical implementation of these conceptual models will be done within the TSPA-SR Model. Thus, this AMR will not include any model results or sensitivity analyses. Calculation of any doses resulting from igneous releases will also be done within the TSPA-SR model, as will the probabilistic weighting of these doses. Calculation and analysis of the TSPA-SR Model results for igneous disruption are, therefore, outside the scope of this activity. The reason for not running the mathematical models as part of this AMR is that the models are integrated within the TSPA-SR model and, thus, any model simulations and the corresponding results are out of the scope of this AMR. The scope of this work as defined in the development plan (CRWMS M&O 2000j) involves using data that has been extracted from existing sources to design and support the TSPA-SR models for the transport of radionuclides following igneous disruption of the repository. The development plan states ''applications of the code in this analysis will be limited to testing of the code and sensitivity analyses during analysis design.'' In contrast to the development plan, the ASHPLUME

  17. Elastic properties of Apollo 14 and 15 rocks.

    NASA Technical Reports Server (NTRS)

    Todd, T.; Wang, H.; Baldridge, W. S.; Simmons, G.

    1972-01-01

    Ultrasonic P- and S-wave velocities of lunar samples 14310,72 and 15418,43 and P-wave velocities of sample 15015,18 were measured at room temperature to 5 kb confining pressure. The velocities of both igneous and breccia samples increased sharply over this pressure range. At low confining pressures, the shape of velocity-pressure curves of rocks is determined by the distribution function of crack aspect ratios. We suggest that analogue studies on terrestrial rocks having a wide assortment of crack parameters may be used to infer the nature of cracks in lunar rocks.

  18. Lead-alpha age determinations of granitic rocks from Alaska

    USGS Publications Warehouse

    Matzko, John J.; Jaffe, H.W.; Waring, C.L.

    1957-01-01

    Lead-alpha activity age determinations were made on zircon from seven granitic rocks of central and southeastern Alaska. The results of the age determinations indicate two periods of igneous intrusion, one about 95 million years ago, during the Cretaceous period, and another about 53 million years ago, during the early part of the Tertiary. The individual ages determined on zircon from 2 rocks from southeastern Alaska and 1 from east-central Alaska gave results of 90, 100, and 96 million years; those determined on 4 rocks from central Alaska gave results of 47, 56, 58, and 51 million years.

  19. A Comparison of Microbial Communities from Deep Igneous Crust

    NASA Astrophysics Data System (ADS)

    Smith, A. R.; Flores, G. E.; Fisk, M. R.; Colwell, F. S.; Thurber, A. R.; Mason, O. U.; Popa, R.

    2013-12-01

    Recent investigations of life in Earth's crust have revealed common themes in organism function, taxonomy, and diversity. Capacities for hydrogen oxidation, carbon fixation, methanogenesis and methanotrophy, iron and sulfur metabolisms, and hydrocarbon degradation often predominate in deep life communities, and crustal mineralogy has been hypothesized as a driving force for determining deep life community assemblages. Recently, we found that minerals characteristic of the igneous crust harbored unique communities when incubated in the Juan de Fuca Ridge flank borehole IODP 1301A. Here we present attached mineral biofilm morphologies and a comparison of our mineral communities to those from a variety of locations, contamination states, and igneous crustal or mineralogical types. We found that differences in borehole mineral communities were reflected in biofilm morphologies. Olivine biofilms were thick, carbon-rich films with embedded cells of uniform size and shape and often contained secondary minerals. Encrusted cells, spherical and rod-shaped cells, and tubes were indicative of glass surfaces. We also found that the attached communities from incubated borehole minerals were taxonomically more similar to native, attached communities from marine and continental crust than to communities from the aquifer water that seeded it. Our findings further support the hypothesis that mineralogy selects for microbial communities that have distinct phylogenetic, morphological, and potentially functional, signatures. This has important implications for resolving ecosystem function and microbial distributions in igneous crust, the largest deep habitat on Earth.

  20. 'Escher' Rock

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site] Chemical Changes in 'Endurance' Rocks

    [figure removed for brevity, see original site] Figure 1

    This false-color image taken by NASA's Mars Exploration Rover Opportunity shows a rock dubbed 'Escher' on the southwestern slopes of 'Endurance Crater.' Scientists believe the rock's fractures, which divide the surface into polygons, may have been formed by one of several processes. They may have been caused by the impact that created Endurance Crater, or they might have arisen when water leftover from the rock's formation dried up. A third possibility is that much later, after the rock was formed, and after the crater was created, the rock became wet once again, then dried up and developed cracks. Opportunity has spent the last 14 sols investigating Escher, specifically the target dubbed 'Kirchner,' and other similar rocks with its scientific instruments. This image was taken on sol 208 (Aug. 24, 2004) by the rover's panoramic camera, using the 750-, 530- and 430-nanometer filters.

    The graph above shows that rocks located deeper into 'Endurance Crater' are chemically altered to a greater degree than rocks located higher up. This chemical alteration is believed to result from exposure to water.

    Specifically, the graph compares ratios of chemicals between the deep rock dubbed 'Escher,' and the more shallow rock called 'Virginia,' before (red and blue lines) and after (green line) the Mars Exploration Rover Opportunity drilled into the rocks. As the red and blue lines indicate, Escher's levels of chlorine relative to Virginia's went up, and sulfur down, before the rover dug a hole into the rocks. This implies that the surface of Escher has been chemically altered to a greater extent than the surface of Virginia. Scientists are still investigating the role water played in influencing this trend.

    These data were taken by the rover's alpha particle X-ray spectrometer.

  1. Rocks and geology in the San Francisco Bay region

    USGS Publications Warehouse

    Stoffer, Philip W.

    2002-01-01

    The landscape of the San Francisco Bay region is host to a greater variety of rocks than most other regions in the United States. This introductory guide provides illustrated descriptions of 46 common and important varieties of igneous, sedimentary, and metamorphic rock found in the region. Rock types are described in context of their identification qualities, how they form, and where they occur in the region. The guide also provides discussion about of regional geology, plate tectonics, the rock cycle, the significance of the selected rock types in relation to both earth history and the impact of mineral resources on the development in the region. Maps and text also provide information where rocks, fossils, and geologic features can be visited on public lands or in association with public displays in regional museums, park visitor centers, and other public facilities.

  2. Metamorphic and thermal evolution of large contact aureoles - lessons from the Bushveld Igneous Complex

    NASA Astrophysics Data System (ADS)

    Waters, D.

    2012-04-01

    Large igneous intrusions crystallise, cool, and transfer heat out into their host rocks. The thermal structure of the resulting aureole can be mapped as a series of assemblage zones and isograds, and can in principle be modelled on the assumption that heat transfer is dominantly by conduction. The local peak of contact metamorphism occurs later in time with increasing distance from the igneous contact. The importance of fluids as a metamorphic/metasomatic agent or heat transfer mechanism depends on volatile contents of magma and country rock, and on the geometry of the intrusion. Many of these features are spectacularly illustrated by the aureole beneath the mafic Rustenburg Layered Suite of the Bushveld Complex, which was emplaced at ca. 2060 Ma sub-concordantly into the shale-quartzite succession of the Pretoria Group in the Transvaal Basin. The layered suite reaches a thickness of at least 8 km, and the metamorphic aureole extends 4 km or more downwards into the "floor" of the intrusion. The great extent and relative absence of deformation make this a remarkable natural laboratory for studying the fundamental processes of metamorphism. In quantifying the thermal history, however, a number of second-order factors need to be taken into account. The first relates to the markedly different thermal properties of the major quartzite and shale units, and the second to the importance of endothermic metamorphic reactions in shale units relative to the quartzites. Further insights into metamorphic processes arise from the exquisite detail of poikiloblast growth microstructures preserved in graphite-poor metapelites of the Timeball Hill and Silverton Formations, 2.5 to 3.5 km beneath the igneous contact. These allow a detailed reconstruction of the time sequence of mineral growth and replacement, revealing a marked overlap of the growth intervals of porphyroblastic staurolite, cordierite, biotite, garnet and andalusite at the expense of muscovite, chlorite and chloritoid

  3. Novel long-chain anteiso-alkanes and anteiso-alkanoic acids in Antarctic rocks colonized by living and fossil cryptoendolithic microorganisms.

    PubMed

    Matsumoto, G I; Friedmann, E I; Watanuki, K; Ocampo-Friedmann, R

    1992-01-01

    Saponified extracts of rock samples colonized by cryptoendolithic microbial communities from the McMurdo Dry Valleys of Southern Victoria Land, Antarctica, were separated into hydrocarbon and fatty acid fractions by silica gel column chromatography. Hydrocarbons and methyl esters of fatty acids were analyzed by capillary gas chromatography-mass spectrometry. Unusually, a suite of long-chain anteiso-alkanes (a-C20 to a-C30) and anteiso-alkanoic acids (a-C20 to a-C30) were detected in many samples, together with straight-chain, branched and/or cyclic and acyclic isoprenoid compounds. These novel compounds are probably derived from unidentified heterotrophic bacteria or symbiotic processes in a unique microbial community in the Antarctic cold desert and suggest the occurrence of a special biosynthetic pathway. Long-chain anteiso-alkanes are probably formed through microbial decarboxylation of corresponding anteiso-alkanoic acids. They may serve as new biomarkers in environmental and geochemical studies.

  4. Novel long-chain anteiso-alkanes and anteiso-alkanoic acids in Antarctic rocks colonized by living and fossil cryptoendolithic microorganisms

    NASA Technical Reports Server (NTRS)

    Matsumoto, G. I.; Friedmann, E. I.; Watanuki, K.; Ocampo-Friedmann, R.

    1992-01-01

    Saponified extracts of rock samples colonized by cryptoendolithic microbial communities from the McMurdo Dry Valleys of Southern Victoria Land, Antarctica, were separated into hydrocarbon and fatty acid fractions by silica gel column chromatography. Hydrocarbons and methyl esters of fatty acids were analyzed by capillary gas chromatography-mass spectrometry. Unusually, a suite of long-chain anteiso-alkanes (a-C20 to a-C30) and anteiso-alkanoic acids (a-C20 to a-C30) were detected in many samples, together with straight-chain, branched and/or cyclic and acyclic isoprenoid compounds. These novel compounds are probably derived from unidentified heterotrophic bacteria or symbiotic processes in a unique microbial community in the Antarctic cold desert and suggest the occurrence of a special biosynthetic pathway. Long-chain anteiso-alkanes are probably formed through microbial decarboxylation of corresponding anteiso-alkanoic acids. They may serve as new biomarkers in environmental and geochemical studies.

  5. 'Earhart' Rock

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This false-color image taken by NASA's Mars Exploration Rover Opportunity shows a rock informally named 'Earhart' on the lower slopes of 'Endurance Crater.' The rock was named after the pilot Amelia Earhart. Like 'Escher' and other rocks dotting the bottom of Endurance, scientists believe fractures in Earhart could have been formed by one of several processes. They may have been caused by the impact that created Endurance Crater, or they might have arisen when water leftover from the rock's formation dried up. A third possibility is that much later, after the rock was formed, and after the crater was created, the rock became wet once again, then dried up and developed cracks. Rover team members do not have plans to investigate Earhart in detail because it is located across potentially hazardous sandy terrain. This image was taken on sol 219 (Sept. 4) by the rover's panoramic camera, using its 750-, 530- and 430-nanometer filters.

  6. An outline of tectonic, igneous, and metamorphic events in the Goshute-Toano Range between Silver Zone Pass and White Horse Pass, Elko County, Nevada; a history of superposed contractional and extensional deformation

    USGS Publications Warehouse

    Ketner, Keith Brindley; Day, Warren C.; Elrick, Maya; Vaag, Myra K.; Zimmerman, Robert A.; Snee, Lawrence W.; Saltus, Richard W.; Repetski, John E.; Wardlaw, Bruce R.; Taylor, Michael E.; Harris, Anita G.

    1998-01-01

    Seven kinds of fault-bounded tracts are described. One of the tracts provides a good example of Mesozoic contractional folding and faulting; six exemplify various aspects of Miocene extensional faulting. Massive landslide deposits resulting from Tertiary faulting are described. Mesozoic intrusive rocks and extensive exposures of Miocene volcanic rocks are described and dated. The age ranges of stratigraphic units were based on numerous conodont collections, and ages of igneous rocks were determined by argon/argon and fission-track methods. The geologic complexity of the Goshute-Toano Range provides opportunities for many additional productive structural studies.

  7. 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.

  8. Rock flows

    NASA Technical Reports Server (NTRS)

    Matveyev, S. N.

    1986-01-01

    Rock flows are defined as forms of spontaneous mass movements, commonly found in mountainous countries, which have been studied very little. The article considers formations known as rock rivers, rock flows, boulder flows, boulder stria, gravel flows, rock seas, and rubble seas. It describes their genesis as seen from their morphological characteristics and presents a classification of these forms. This classification is based on the difference in the genesis of the rubbly matter and characterizes these forms of mass movement according to their source, drainage, and deposit areas.

  9. Spectral-induced polarization characteristics of rocks from Shinyemi deposit in Northeastern South Korea

    NASA Astrophysics Data System (ADS)

    Park, Samgyu; Shin, Seung Wook; Son, Jeong-Sul; Kim, Changryol

    2016-04-01

    Contact metasomatism between carbonate and igneous rocks leads to the formation of skarn deposits, and ore minerals are abundant. Geophysical methods that visualize the distributions of physical properties have been utilized to determine lithological boundaries in ore deposits. In particular, spectral-induced polarization (SIP) is the most effective of those methods for mineral exploration because it can obtain not only the boundaries but also the abundance and grain size of ore minerals. It is crucial to characterize the SIP responses of in situ rocks for a more realistic interpretation. Thus, typical rocks composed of igneous rock, skarn rock, skarn ore, and carbonate rock were sampled from drilling cores in the Shinyemi deposit, which is one of the well-known skarn deposits in Northeastern South Korea. The purpose of this study was to characterize the SIP responses of rocks by laboratory measurements. The characterization was performed by evaluating spectra and IP parameters. The IP properties were acquired from equivalent circuit analysis using a circuit model based on the electrochemical theory, and the analysis results of this circuit model were relatively well fit compared with those of the traditional Dias and Cole-Cole models. The frequency responses below 100 Hz in the spectra and the chargeability values of the skarn rocks and ores containing magnetite were relatively strong and high, respectively, compared with those of non-mineralized igneous and carbonate rocks. Therefore, it is considered that these characteristics are dependent on the abundance of magnetite. In case of the skarn ores with high magnetite content, the resistivity values were significantly low and the relaxation time values were influenced by the grain size of magnetite. On the other hand, it is considered that the DC resistivity and the relaxation time values of the igneous and carbonate rocks are slightly related to the porosity and the grade of hydrothermal alteration, respectively.

  10. Igneous activity and related ore deposits in the western and southern Tushar Mountains, Marysvale volcanic field, west-central Utah

    USGS Publications Warehouse

    Steven, Thomas A.

    1984-01-01

    PART A: Igneous activity in the Marysvale volcanic field of western Utah can be separated into many episodes of extrusion, intrusion, and hydrothermal activity. The rocks of the western Tushar Mountains, near the western part of the volcanic field, include intermediate-composition, calc-alkalic volcanic rocks erupted from scattered volcanoes in Oligocene through earliest Miocene time and related monzonitic intrusions emplaced 24-23 m.y. ago. Beginning 22-21 m.y. ago and extending through much of the later Cenozoic, a bimodal basalt-rhyolite assemblage was erupted widely throughout the volcanic field. Only volcanic and intrusive rocks belonging to the rhyolitic end member of this bimodal assemblage are present in the western Tushar Mountains; most of these rocks either fill the Mount Belknap caldera (19 m.y. old) or are part of the rhyolite of Gillies Hill (9---8 m.y. old). Episodic hydrothermal activity altered and mineralized rocks at many places in the western Tushar Mountains during Miocene time. The earliest activity took place in and adjacent to monzonitic calcalkalic intrusions emplaced in the vicinity of Indian Creek and Cork Ridge. These rocks were widely propylitized, and gold-bearing quartz-pyrite-carbonate veins formed in local fractures. Hydrothermal activity associated with the Mount Belknap caldera mobilized and redeposited uranium contained in the caldera-fill rocks and formed primary concentrations of lithophile elements (including molybdenum and uranium) in the vicinity of intrusive bodies. Hydrothermal activity associated with the rhyolite of Gillies Hill altered and mineralized rocks at several places along the fault zone that marks the western margin of the Tushar Mountains; the zoned alunite and gold deposits at Sheep Rock, the gold deposit at the Sunday Mine, and an alunite deposit near Indian Creek were thus produced. Resetting of isotopic ages suggests that another center of hydrothermally altered rocks associated with a buried pluton about

  11. Spectral characterization of volcanic rocks in the VIS-NIR for martian exploration

    NASA Astrophysics Data System (ADS)

    De Angelis, Simone; Carli, Cristian; Manzari, Paola; De Sanctis, Maria Cristina; Capaccioni, Fabrizio

    2016-10-01

    Igneous effusive rocks cover much of the surface of Mars [1,2,3]. Initially only two types of lithologies were thought to constitute the Martian crust, i.e. a basaltic one and a more andesitic one [1,2], while more evolved lithologies were ruled out.Nevertheless a more complex situation is appearing in the last years. Recently several observations have highlighted the presence of evolved, acidic rocks. High-silica dacite units were identified in Syrtis Major caldera by thermal IR data [4]. Outcrops in Noachis Terra were interpreted as constituted of felsic (i.e. feldspar-rich) rocks essentially by the observation of a 1.3-µm spectral feature in CRISM data, attributed to Fe2+ in feldspars [5]. However different interpretations exist, invoking plagioclase-enriched basalts [6] rather than felsic products.The increasing of high-resolution and in-situ rover-based observations datasets and the changing of the initial paradigm justify a new systematic spectral study of igneous effusive rocks. In this work we focus on the spectral characterization of volcanic effusive rocks in the 0.35-2.5-µm range. We are carrying out measurements and spectral analyses on a wide ensemble of effusive samples, from mafic to sialic, with variable alkali contents, following the classification in the Total-Alkali-Silica diagram, and discussing the influence on spectral characteristics of different mineral assemblages and/or texture ([7], [8]). [1] Bandfield J.L., et al., Science, 287, 1626, 2000; [2] Christensen P.R., et al., J. Geophys. Res., 105, N.E4, 9609-9621, 2000; [3] Ehlmann B.L. & Edwards C.S., Annu. Rev. Earth Planet. Sci., 42, 291-315, 2014; [4] Christensen P.R., et al., Nature, 436, 504-509, 2005; [5] Wray J.J., et al., 44th LPSC, abs. n.3065, 2013; [6] Rogers A.D. & Nekvasil H., Geophys. Res. Lett., 42, 2619-2626, 2015; [7] Carli C. and Sgavetti M.,Icarus, 211, 1034-1048, 2011; [7] Carli C. et al., SGL, doi 10.1144/SP401.19, 2015.

  12. Effects of low molecular weight organic acids on the immobilization of aqueous Pb(II) using phosphate rock and different crystallized hydroxyapatite.

    PubMed

    Wei, Wei; Cui, Jing; Wei, Zhenggui

    2014-06-01

    Understanding the effects of low molecular weight organic acids (LMWOAs) on the transformation of Pb(II) to geochemically stable pyromorphite (PY) by apatite materials (AMs), has considerable benefits for risk asse