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Sample records for lherzolitic shergottite yamato

  1. Sm-Nd isotopic systematics of lherzolitic shergottite Yamato-793605

    USGS Publications Warehouse

    Misawa, K.; Yamada, K.; Nakamura, N.; Morikawa, N.; Yamashita, K.; Premo, W.R.

    2006-01-01

    We have undertaken Sm-Nd isotopic studies on Yamato-793605 lherzolitic shergottite. The Sm-Nd internal isochron obtained for acid leachates and residues of whole-rock and separated mineral fractions yields an age of 185 ??16 Ma with an initial ??Nd value of +9.7??0.2. The obtained Sm-Nd age is, within analytical errors, identical to the Rb-Sr age of this meteorite as well as to the previous Rb-Sr and Sm-Nd ages of Allan Hills-77005 and Lewis Cliff 88516, although the ??Nd values are not identical to each other. Elemental abundances of lithophile trace elements remain nearly unaffected by aqueous alteration on the Martian surface. The isotopic systems of lherzolitic shergottites, thus, are considered to be indigenous, although disturbances by shock metamorphism are clearly observed. "Young ages of ??? 180 Ma" have been consistently obtained from this and previous Rb-Sr, Sm-Nd and U-Pb isotopic studies and appear to represent crystallization events. ?? 2006 National Institute of Polar Research.

  2. Rb-Sr Isotopic Studies Of Antarctic Lherzolitic Shergottite Yamato 984028

    NASA Technical Reports Server (NTRS)

    Shih, C.-Y.; Nyquist, L. E.; Reese, Y.; Misawa, K.

    2009-01-01

    Yamato 984028 is a Martian meteorite found in the Yamato Mountains of Antarctica. It is classified as a lherzolitic shergottite and petrographically resembles several other lherzolitic shergottites, i.e. ALHA 77005, LEW 88516, Y-793605 and Y-000027/47/97 [e.g. 2-5]. These meteorites have similarly young crystallization ages (152-185 Ma) as enriched basaltic shergottites (157-203 Ma), but have very different ejection ages (approximately 4 Ma vs. approximately 2.5 Ma), thus they came from different martian target crater areas. Lherzolitic shergottites have mg-values approximately 0.70 and represent the most mafic olivine-pyroxene cumulates. Their parental magmas were melts derived probably from the primitive Martian mantle. Here we present Rb-Sr isotopic data for Y-984028 and compare these data with those obtained from other lherzolitic and olivine-phyric basaltic shergottites to better understand the isotopic characteristics of their primitive mantle source regions. Corresponding Sm-Nd analyses for Y-984028 are in progress.

  3. Tracking the Martian Mantle Signature in Olivine-Hosted Melt Inclusions of Basaltic Shergottites Yamato 980459 and Tissint

    NASA Technical Reports Server (NTRS)

    Peters, T. J.; Simon, J. I.; Jones, J. H.; Usui, T.; Moriwaki, R.; Economos, R.; Schmitt, A.; McKeegan, K.

    2014-01-01

    The Martian shergottite meteorites are basaltic to lherzolitic igneous rocks that represent a period of relatively young mantle melting and volcanism, approximately 600-150 Ma (e.g. [1,2]). Their isotopic and elemental composition has provided important constraints on the accretion, evolution, structure and bulk composition of Mars. Measurements of the radiogenic isotope and trace element concentrations of the shergottite meteorite suite have identified two end-members; (1) incompatible trace element enriched, with radiogenic Sr and negative epsilon Nd-143, and (2) incompatible traceelement depleted, with non-radiogenic Sr and positive epsilon 143-Nd(e.g. [3-5]). The depleted component represents the shergottite martian mantle. The identity of the enriched component is subject to debate, and has been proposed to be either assimilated ancient martian crust [3] or from enriched domains in the martian mantle that may represent a late-stage magma ocean crystallization residue [4,5]. Olivine-phyric shergottites typically have the highest Mg# of the shergottite group and represent near-primitive melts having experienced minimal fractional crystallization or crystal accumulation [6]. Olivine-hosted melt inclusions (MI) in these shergottites represent the most chemically primitive components available to understand the nature of their source(s), melting processes in the martian mantle, and origin of enriched components. We present trace element compositions of olivine hosted melt inclusions in two depleted olivinephyric shergottites, Yamato 980459 (Y98) and Tissint (Fig. 1), and the mesostasis glass of Y98, using Secondary Ionization Mass Spectrometry (SIMS). We discuss our data in the context of understanding the nature and origin of the depleted martian mantle and the emergence of the enriched component.

  4. Two-stage polybaric formation of the new enriched, pyroxene-oikocrystic, lherzolitic shergottite, NWA 7397

    NASA Astrophysics Data System (ADS)

    Howarth, Geoffrey H.; Pernet-Fisher, John F.; Balta, J. Brian; Barry, Peter H.; Bodnar, Robert J.; Taylor, Lawrence A.

    2014-10-01

    Northwest Africa (NWA) 7397 is a newly discovered, enriched, lherzolitic shergottite, the third described example of this group. This meteorite consists of two distinct textural lithologies (1) poikilitic—comprised of zoned pyroxene oikocrysts, with chadacrysts of chromite and olivine, and (2) nonpoikilitic—comprised of olivine, low-Ca and high-Ca pyroxene, maskelynite, and minor abundances of merrillite, spinel, ilmenite, and pyrrhotite. The constant Ti/Al ratios of pyroxene oikocrysts suggests initial crystallization of the poikilitic lithology at depth (equivalent to pressures of approximately 10 kbar), followed by crystallization of the nonpoikilitic lithology at shallower levels. Oxygen fugacity conditions become more oxidizing during crystallization ranging from fO2 conditions of approximately QFM-2 to QFM-0.7. Magma calculated to be in equilibrium with the major rock-forming minerals is LREE-enriched relative to depleted or intermediate shergottites and has flat overall profiles. Therefore, we suggest that the parental magma for NWA 7397 had sampled an enriched, oxidized, Martian geochemical source, similar to that of other enriched basaltic and olivine-phyric shergottites. We present a polybaric formation model for the lherzolitic shergottite NWA 7397, to account for the petrologic constraints. Three successive stages in the development of NWA 7397 are discussed (1) formation of a REE-enriched parental magma from a distinct Martian mantle reservoir; (2) magma ponding and development of a staging chamber concomitant with initial crystallization of the poikilitic lithology; and (3) magma ascent to the near surface, with entrainment of cumulates from the staging chamber and subsequent crystallization of the nonpoikilitic lithology en route to the surface.

  5. Igneous cooling history of olivine-phyric shergottite Yamato 980459 constrained by dynamic crystallization experiments

    NASA Astrophysics Data System (ADS)

    First, Emily; Hammer, Julia

    2016-05-01

    Dynamic crystallization experiments were performed on a liquid having the bulk composition of olivine-phyric shergottite Yamato 980459, to constrain the igneous thermal history of this meteorite. Key characteristics of the meteorite's mineralogy and texture, including several morphologically distinct olivine and pyroxene crystal populations and a glassy mesostasis devoid of plagioclase, were replicated upon cooling from 1435 to 909 °C at 1 atmosphere under reducing conditions. Three sequential cooling ramps are required to produce synthetic samples with textures and compositions matching Yamato 980459. Olivine phenocrysts formed at <1 °C h-1, presumably at depth in the Martian crust. Pyroxene phenocrysts formed mainly at ~10 °C h-1, consistent with crystallization within a lava flow at depths of 25-45 cm. Increased cooling rate (~100 °C h-1) in a third stage suppressed the formation of plagioclase and produced groundmass crystals, consistent with crystallization at lava flow depths of 5-7 cm. Although Y 980459 is unique among Martian meteorites (i.e., preserving a primary glassy mesostasis), its emplacement did not require unique physical conditions. Rather, the second and third cooling stages may reflect cooling within the core of a pāhoehoe-like flow and subsequent breakout on the surface of Mars.

  6. Igneous cooling history of olivine-phyric shergottite Yamato 980459 constrained by dynamic crystallization experiments

    NASA Astrophysics Data System (ADS)

    First, Emily; Hammer, Julia

    2016-07-01

    Dynamic crystallization experiments were performed on a liquid having the bulk composition of olivine-phyric shergottite Yamato 980459, to constrain the igneous thermal history of this meteorite. Key characteristics of the meteorite's mineralogy and texture, including several morphologically distinct olivine and pyroxene crystal populations and a glassy mesostasis devoid of plagioclase, were replicated upon cooling from 1435 to 909 °C at 1 atmosphere under reducing conditions. Three sequential cooling ramps are required to produce synthetic samples with textures and compositions matching Yamato 980459. Olivine phenocrysts formed at <1 °C h-1, presumably at depth in the Martian crust. Pyroxene phenocrysts formed mainly at ~10 °C h-1, consistent with crystallization within a lava flow at depths of 25-45 cm. Increased cooling rate (~100 °C h-1) in a third stage suppressed the formation of plagioclase and produced groundmass crystals, consistent with crystallization at lava flow depths of 5-7 cm. Although Y 980459 is unique among Martian meteorites (i.e., preserving a primary glassy mesostasis), its emplacement did not require unique physical conditions. Rather, the second and third cooling stages may reflect cooling within the core of a pāhoehoe-like flow and subsequent breakout on the surface of Mars.

  7. Concordant Rb-Sr and Sm-Nd Ages for NWA 1460: A 340 Ma Old Basaltic Shergottite Related to Lherzolitic Shergottites

    NASA Technical Reports Server (NTRS)

    Nyquist, L. E.; Shih, C-Y; Reese, Y. D.; Irving, A. J.

    2006-01-01

    Preliminary Rb-Sr and Sm-Nd ages reported by [1] for the NWA 1460 basaltic shergottite are refined to 336+/-14 Ma and 345+/-21 Ma, respectively. These concordant ages are interpreted as dating a lava flow on the Martian surface. The initial Sr and Nd isotopic compositions of NWA 1460 suggest it is an earlier melting product of a Martian mantle source region similar to those of the lherzolitic shergottites and basaltic shergottite EETA79001, lithology B. We also examine the suggestion that generally "young" ages for other Martian meteorites should be reinterpreted in light of Pb-207/Pb-206 - Pb-204/Pb-206 isotopic systematics [2]. Published U-Pb isotopic data for nakhlites are consistent with ages of approx.1.36 Ga. The UPb isotopic systematics of some Martian shergottites and lherzolites that have been suggested to be approx.4 Ga old [2] are complex. We nevertheless suggest the data are consistent with crystallization ages of approx.173 Ma when variations in the composition of in situ initial Pb as well as extraneous Pb components are considered.

  8. Spinels and oxygen fugacity in olivine-phyric and lherzolitic shergottites

    NASA Astrophysics Data System (ADS)

    Goodrich, C. A.; Herd, C. D. K.; Taylor, L. A.

    2003-12-01

    We examine the occurrences, textures, and compositional patterns of spinels in the olivine- phyric shergottites Sayh al Uhaymir (SaU) 005, lithology A of Elephant Moraine A79001 (EET-A), Dhofar 019, and Northwest Africa (NWA) 1110, as well as the lherzolitic shergottite Allan Hills (ALH) A77005, in order to identify spinel-olivine-pyroxene assemblages for the determination of oxygen fugacity (using the oxybarometer of Wood [1991]) at several stages of crystallization. In all of these basaltic martian rocks, chromite was the earliest phase and crystallized along a trend of strict Cr-Al variation. Spinel (chromite) crystallization was terminated by the appearance of pyroxene but resumed later with the appearance of ulvospinel. Ulvospinel formed overgrowths on early chromites (except those shielded as inclusions in olivine or pyroxene), retaining the evidence of the spinel stability gap in the form of a sharp core/rim boundary (except in ALH A77005, where subsolidus reequilibration diffused this boundary). Secondary effects seen in chromites include reaction with melt before ulvospinel overgrowth, reaction with melt inclusions, reaction with olivine hosts (in ALH A77005), and exsolution of ulvospinel or ilmenite. All chromites experienced subsolidus Fe/Mg reequilibration. Spinel-olivine-pyroxene assemblages representing the earliest stages of crystallization in each rock essentially consist of the highest-Cr#, lowest-fe# chromites not showing secondary effects plus the most magnesian olivine and equilibrium low-Ca pyroxene. Assemblages representing the onset of ulvospinel crystallization consist of the lowest-Ti ulvospinel, the most magnesian olivine in which ulvospinel occurs as inclusions, and equilibrium low-Ca pyroxene. The results show that, for early crystallization conditions, oxygen fugacity (fO2) increases from SaU 005 and Dhofar 019 (~QFM -3.8), to EET-A (QFM -2.8) and ALH A77005 (QFM -2.6), to NWA 1110 (QFM -1.7). Estimates for later conditions indicate

  9. Experimental Petrology of the Basaltic Shergottite Yamato 980459: Implications for the Thermal Structure of the Martian Mantle

    NASA Technical Reports Server (NTRS)

    Dalton, H. A.; Musselwhite, D. S.; Kiefer, W.; Treiman, A. H.

    2005-01-01

    Yamato 980459 (Y98) is an olivine-phyric basaltic shergottite composed of 48% pyroxene, 26% olivine, 25% mesostasis, and 1% other minerals. Unlike the other Martian basalts, it contains no plagioclase. Olivine in Y98 is the most magnesian of all Martian meteorites. Thus Y98 is believed to be the most primitive and its composition may be the closest to a primary or direct melt of the Martian mantle. As such, it provides a very useful probe of the mineralogy and depth of its mantle source region. Toward this end, we are conducting crystallization experiments on a synthetic Y98 composition at Martian mantle pressures and temperatures.

  10. Experimental study of polybaric REE partitioning between olivine, pyroxene and melt of the Yamato 980459 composition: Insights into the petrogenesis of depleted shergottites

    NASA Astrophysics Data System (ADS)

    Blinova, Alexandra; Herd, Christopher D. K.

    2009-06-01

    A synthetic composition representing the Yamato 980459 martian basalt (shergottite) has been used to carry out phase relation, and rare earth element (REE) olivine and pyroxene partitioning experiments. Yamato 980459 is a sample of primitive basalt derived from a reduced end-member among martian mantle sources. Experiments carried out between 1-2 GPa and 1350-1650 °C simulate the estimated pressure-temperature conditions of basaltic melt generation in the martian mantle. Olivine-melt and orthopyroxene-melt partition coefficients for La, Nd, Sm, Eu, Gd and Yb ( DREE values) were determined by LA-ICPMS, and are similar to the published values for terrestrial basaltic systems. We have not detected significant variation in D-values with pressure over the range investigated, and by comparison with previous studies carried out at lower pressure. We apply the experimentally obtained olivine-melt and orthopyroxene-melt DREE values to fractional crystallization and partial melting models to develop a three-stage geochemical model for the evolution of martian meteorites. In our model we propose two ancient (˜4.535 Ga) sources: the Nakhlite Source, located in the shallow mantle, and the Deep Mantle Source, located close to the martian core-mantle boundary. These two sources evolved distinctly on the ɛ 143Nd evolution curve due to their different Sm/Nd ratios. By partially melting the Nakhlite Source at ˜1.3 Ga, we are able to produce a slightly depleted residue (Nakhlite Residue). The Nakhlite Residue is left undisturbed until ˜500 Ma, at which point the depleted Deep Mantle Source is brought up by a plume mechanism carrying with it high heat flow, melts and isotopic signatures of the deep mantle (e.g., ɛ 182W, ɛ 142Nd, etc.). The plume-derived Deep Mantle Source combines with the Nakhlite Residue producing a mixture that becomes a mantle source (herein referred to as "the Y98 source") for Yamato 980459 and the other depleted shergottites with the characteristic range

  11. Constraints on Mantle Plume Melting Conditions in the Martian Mantle Based on Improved Melting Phase Relationships of Olivine-Phyric Shergottite Yamato 980459

    NASA Technical Reports Server (NTRS)

    Kiefer, Walter S.; Rapp, Jennifer F.; Usui, Tomohiro; Draper, David S.; Filiberto, Justin

    2016-01-01

    Martian meteorite Yamato 980459 (hereafter Y98) is an olivine-phyric shergottite that has been interpreted as closely approximating a martian mantle melt [1-4], making it an important constraint on adiabatic decompression melting models. It has long been recognized that low pressure melting of the Y98 composition occurs at extremely high temperatures relative to martian basalts (1430 degC at 1 bar), which caused great difficulties in a previous attempt to explain Y98 magma generation via a mantle plume model [2]. However, previous studies of the phase diagram were limited to pressures of 2 GPa and less [2, 5], whereas decompression melting in the present-day martian mantle occurs at pressures of 3-7 GPa, with the shallow boundary of the melt production zone occurring just below the base of the thermal lithosphere [6]. Recent experimental work has now extended our knowledge of the Y98 melting phase relationships to 8 GPa. In light of this improved petrological knowledge, we are therefore reassessing the constraints that Y98 imposes on melting conditions in martian mantle plumes. Two recently discovered olivine- phyric shergottites, Northwest Africa (NWA) 5789 and NWA 6234, may also be primary melts from the martian mantle [7, 8]. However, these latter meteorites have not been the subject of detailed experimental petrology studies, so we focus here on Y98.

  12. Evidence for the exsolution of Cl-rich fluids in martian magmas: Apatite petrogenesis in the enriched lherzolitic shergottite Northwest Africa 7755

    NASA Astrophysics Data System (ADS)

    Howarth, G. H.; Pernet-Fisher, J. F.; Bodnar, R. J.; Taylor, L. A.

    2015-10-01

    Martian meteorite Northwest Africa 7755 is a new example of an enriched, lherzolitic shergottite, containing some of the coarsest-grained apatite yet identified in shergottite meteorites. Their size has permitted detailed observations of volatile distributions within single grains. We have demonstrated that some apatites have been invaded by shock melts, which act to devolatilize parts of grains, resulting in significant Cl-enrichment in the adjacent regions. The extent of chemical heterogeneity within single grains must be carefully considered in other shergottites, so that the effects of secondary modification of apatites are well-constrained, prior to interpreting the volatile contents and primary magmatic processes. Apatite grains unaffected by shock melts are OH-F enriched and Cl-poor (∼F50Cl14OH36), relative to interstitial apatites reported in other shergottites. The volatile compositions are similar to interstitial apatites reported in terrestrial mafic intrusions. Such apatites in terrestrial intrusions are argued to have formed after significant Cl-loss due to the exsolution and migration of Cl-rich brines. Calculated relative F2, Cl2, and H2O fugacities for NWA 7755 apatites show a trend of degassing rather than fractionation, noted in previous studies. Indeed, we interpret the volatile contents of apatites analyzed in the cumulate shergottite NWA 7755 to represent snapshots of the evolving late-stage residual liquid during exsolution of a Cl-rich brine. This fluid phase has subsequently been lost from an open magma system, migrating upward through the cumulate sequence enriching residual liquids in Cl. Alternatively, it formed a hydrothermal system in the martian crust surrounding the intrusion. Furthermore, by comparison with terrestrial examples, we suggest that the late-stage evolution of volatile-bearing phases in NWA 7755 is similar to that of comparable terrestrial mafic rocks. Primary cumulus apatites are F-rich, whereas interstitial apatites

  13. Tracking the source of the enriched martian meteorites in olivine-hosted melt inclusions of two depleted shergottites, Yamato 980459 and Tissint

    NASA Astrophysics Data System (ADS)

    Peters, T. J.; Simon, J. I.; Jones, J. H.; Usui, T.; Moriwaki, R.; Economos, R. C.; Schmitt, A. K.; McKeegan, K. D.

    2015-05-01

    The apparent lack of plate tectonics on all terrestrial planets other than Earth has been used to support the notion that for most planets, once a primitive crust forms, the crust and mantle evolve geochemically-independent through time. This view has had a particularly large impact on models for the evolution of Mars and its silicate interior. Recent data indicating a greater potential that there may have been exchange between the martian crust and mantle has led to a search for additional geochemical evidence to support the alternative hypothesis, that some mechanism of crustal recycling may have operated early in the history of Mars. In order to study the most juvenile melts available to investigate martian mantle source(s) and melting processes, the trace element compositions of olivine-hosted melt inclusions for two incompatible-element-depleted olivine-phyric shergottites, Yamato 980459 (Y98) and Tissint, and the interstitial glass of Y98, have been measured by Secondary Ionization Mass Spectrometry (SIMS). Chondrite-normalized Rare Earth Element (REE) patterns for both Y98 and Tissint melt inclusions, and the Y98 interstitial glass, are characteristically light-REE depleted and parallel those of their host rock. For Y98, a clear flattening and upward inflection of La and Ce, relative to predictions based on middle and heavier REE, provides evidence for involvement of an enriched component early in their magmatic history; either inherited from a metasomatized mantle or crustal source, early on and prior to extensive host crystallization. Comparing these melt inclusion and interstitial glass analyses to existing melt inclusion and whole-rock data sets for the shergottite meteorite suite, defines mixing relationships between depleted and enriched end members, analogous to mixing relationships between whole rock Sr and Nd isotopic measurements. When considered in light of their petrologic context, the origin of these trace element enriched and isotopically

  14. Yamato 980459: Crystallization of Martian Magnesian Magma

    NASA Technical Reports Server (NTRS)

    Koizumi, E.; Mikouchi, T.; McKay, G.; Monkawa, A.; Chokai, J.; Miyamoto, M.

    2004-01-01

    Recently, several basaltic shergottites have been found that include magnesian olivines as a major minerals. These have been called olivinephyric shergottites. Yamato 980459, which is a new martian meteorite recovered from the Antarctica by the Japanese Antarctic expedition, is one of them. This meteorite is different from other olivine-phyric shergottites in several key features and will give us important clues to understand crystallization of martian meteorites and the evolution of Martian magma.

  15. Petrology and shock metamorphism of the olivine-phyric shergottite Yamato 980459 - Evidence for a two-stage cooling and a single-stage ejection history

    NASA Astrophysics Data System (ADS)

    Greshake, Ansgar; Fritz, Jörg; Stöffler, Dieter

    2004-05-01

    The basaltic Martian meteorite Yamato 980459 consists of large olivine phenocrysts and often prismatic pyroxenes set into a fine-grained groundmass of smaller more Fe-rich olivine, chromite, and an interstitial residual material displaying quenching textures of dendritic olivine, chain-like augite and sulfide droplets in a glassy matrix. Yamato 980459 is, thus, the only Martian meteorite without plagioclase/maskelynite. Olivine is compositionally zoned from a Mg-rich core to a Fe-rich rim with the outer few micrometers being especially rich in iron. With Fo 84 the cores are the most magnesian olivines found in Martian meteorites so far. Pyroxenes are also mostly composite crystals of large orthopyroxene cores and thin Ca-rich overgrowths. Separate pigeonite and augites are rare. On basis of the mineral compositions, the cooling rates determined from crystal morphologies, and crystal grain size distributions it is deduced that the parent magma of Yamato 980459 initially cooled under near equilibrium conditions e.g., in a magma chamber allowing chromite and the Mg-rich silicates to form as cumulus phases. Fractional crystallization at higher cooling rates and a low degree of undercooling let to the formation of the Ca-, Al-, and Fe-rich overgrowths on olivine and orthopyroxene while the magma was ascending towards the Martian surface. Finally and before plagioclase and also phosphates could precipitate, the magma was very quickly erupted quenching the remaining melt to glass, dendritic silicates and sulfide droplets. The shape preferred orientation of olivine and pyroxene suggests a quick, thin outflow of lava. According to the shock effects found in the minerals of Yamato 980459, the meteorite experienced an equilibration shock pressure of about 20-25 GPa. Its near surface position allowed the ejection from the planet's surface already by a single impact event and at relatively low shock pressures.

  16. Experimental Crystallization of Yamato 980459

    NASA Technical Reports Server (NTRS)

    Jones, John H.; Galenas, M. G.; Danielson, L. R.

    2009-01-01

    Currently, only two martian meteorites QUE 94201 (QUE) and Yamato 980459 (Y98) have been experimentally shown to me true melt compositions. Most martian meteorites are instead, cumulates or partial cumulates. We have performed experiments on a Y98 composition to assess whether QUE could be related to Y98 by some fractionation process [1]. Y98 is a basaltic shergottite from the SNC (Shergotty, Nakhla, Chassigny) meteorite group. Y98 is composed of 26% olivine, 48% pyroxene, 25% mesostasis, and no plagioclase [2]. The large size of the olivine megacrysts and absence of plagioclase suggest that the parental melt which formed this meteorite had begun cooling slowly until some mechanism, such as magma ascent, caused rapid cooling [3]. Y98 s olivines have the highest Mg content of all the shergottites suggesting that it is the most primitive [4]. Y98 has been determined to be a melt composition by comparing the composition of experimental liquidus olivines with the composition of the cores of Y98 olivines [4]. The liquidus of Y98 is predicted by MELTS [5] and by experimentation [6] to be 1450 C. Analyses of Y98 show it to be very depleted in LREEs and it has similar depleted patterns as other shergottites such as QUE [7].

  17. Rb-Sr and Sm-Nd Studies of Olivine-Phyric Shergottites RBT 04262 and LAR 06319: Isotopic Evidence for Relationship to Enriched Basaltic Shergottites

    NASA Technical Reports Server (NTRS)

    Nyquist, L.E.; Shih, C.-Y.; Reese, Y.

    2009-01-01

    RBT 04262 and LAR 06319 are two Martian meteorites recently discovered in Antarctica. Both contain abundant olivines, and were classified as olivine-phyric shergottites. A detailed petrographic study of RBT 04262 suggested it should be reclassified as a lherzolitic shergottite. However, the moderately LREE-depleted REE distribution pattern indicated that it is closely related to enriched basaltic shergottites like Shergotty, Zagami, Los Angeles, etc. In earlier studies of a similarly olivinephyric shergottite NWA 1068 which contains 21% modal olivine, it was shown that it probably was produced from an enriched basaltic shergottite magma by olivine accumulation . As for LAR 06319, recent petrographic studies suggested that it is different from either lherzolitic shergottites or the highly LREE-depleted olivine-phyric shergottites. We performed Rb-Sr and Sm-Nd isotopic analyses on RBT 04262 and LAR 06319 to determine their crystallization ages and Sr and Nd isotopic signatures, and to better understand the petrogenetic relationships between them and other basaltic, lherzolitic and depleted olivine-phyric shergottites.

  18. Radiocarbon datings of Yamato meteorites

    NASA Technical Reports Server (NTRS)

    Kigoshi, K.; Matsuda, E.

    1986-01-01

    The terrestrial ages of five Yamato Meteorites were measured by the content of cosmic-ray-produced carbon-14. Three Yamato Meteorites Y-74013, Y-74097, and Y-74136, which are all diogenites, were found at sites from one to two kilometers apart from each other. Evidence is presented for these three meteorites being a single meteorite. Also presented is a method adopted in the experimental procedure which includes a check for modern carbon contamination in the meteorites.

  19. The parent magma of xenoliths in shergottite EETA79001: Bulk and trace element composition inferred from magmatic inclusions

    NASA Technical Reports Server (NTRS)

    Treiman, Allan H.; Lindstrom, David J.; Martinez, Rene R.

    1994-01-01

    The SNC meteorites are samples of the Martian crust, so inferences about their origins and parent magmas are of wide planetologic significance. The EETA79001 shergottite, a basalt, contains xenoliths of pyroxene-olivine cumulate rocks which are possibly related to the ALHA77005 and LEW88516 SNC lherzolites. Olivines in the xenoliths contain magmatic inclusions, relics of magma trapped within the growing crystals. The magmatic inclusions allow a parent magma composition to be retrieved; it is similar to the composition reconstructed from xenolith pyroxenes by element distribution coefficients. The xenolith parent magma is similar but not identical to parent magmas for the shergottite lherzolites.

  20. Constraints on the Parental Melts of Enriched Shergottites from Image Analysis and High Pressure Experiments

    NASA Technical Reports Server (NTRS)

    Collinet, M.; Medard, E.; Devouard, B.; Peslier, A.

    2012-01-01

    Martian basalts can be classified in at least two geochemically different families: enriched and depleted shergottites. Enriched shergottites are characterized by higher incompatible element concentrations and initial Sr-87/Sr-86 and lower initial Nd-143/Nd-144 and Hf-176/Hf-177 than depleted shergottites [e.g. 1, 2]. It is now generally admitted that shergottites result from the melting of at least two distinct mantle reservoirs [e.g. 2, 3]. Some of the olivine-phyric shergottites (either depleted or enriched), the most magnesian Martian basalts, could represent primitive melts, which are of considerable interest to constrain mantle sources. Two depleted olivine-phyric shergottites, Yamato (Y) 980459 and Northwest Africa (NWA) 5789, are in equilibrium with their most magnesian olivine (Fig. 1) and their bulk rock compositions are inferred to represent primitive melts [4, 5]. Larkman Nunatak (LAR) 06319 [3, 6, 7] and NWA 1068 [8], the most magnesian enriched basalts, have bulk Mg# that are too high to be in equilibrium with their olivine megacryst cores. Parental melt compositions have been estimated by subtracting the most magnesian olivine from the bulk rock composition, assuming that olivine megacrysts have partially accumulated [3, 9]. However, because this technique does not account for the actual petrography of these meteorites, we used image analysis to study these rocks history, reconstruct their parent magma and understand the nature of olivine megacrysts.

  1. Exposure history of shergottites

    NASA Technical Reports Server (NTRS)

    Nishizumi, K.; Arnold, J. R.; Klein, J.; Middleton, R.; Elmore, D.

    1986-01-01

    The cosmogenic nuclides Cl-36, Al-26, Be-10, and Mn-53 were analyzed in Shergotty, ALHA 77005, and EETA 79001 shergottites by means of accelerator mass spectrometry and neutron activation. The cosmogenic radionuclide data were combined with noble gas data and cosmic ray track data to obtain the exposure ages, terrestrial ages, preatmospheric radii, and ablation depths for the three shergottites. The results indicate that none of the three meteorites was irradiated measurably by cosmic rays on its parent body, and that all three objects were ejected from greater than a 3-m depth in their parent bodies. The EETA 79001 meteorite was ejected in an event distinct from that of ALHA 77005 and Shergotty. All three shergottites show a very small amount of ablation, suggesting low velocities on entry into the earth's atmosphere.

  2. Melt Inclusion Analysis of RBT 04262 with Relationship to Shergottites and Mars Surface Compositions

    NASA Technical Reports Server (NTRS)

    Potter, S. A.; Brandon, A. D.; Peslier, A. H.

    2015-01-01

    Martian meteorite RBT 04262 is in the shergottite class. It displays the two lithologies typically found in "lherzolitic shergottites": one with a poikilitic texture of large pyroxene enclosing olivine and another with non-poikilitic texture. In the case of RBT 04262, the latter strongly ressembles an olivine- phyric shergottite which led the initial classification of this meteorite in that class. RBT 04262 has been studied with regards to its petrology, geochemistry and cosmic ray exposure and belongs to the enriched oxidized end-member of the shergottites. Studies on RBT 04262 have primarily focused on the bulk rock composition or each of the lithologies independently. To further elucidate RBT 04262's petrology and use it to better understand Martian geologic history, an in-depth study of its melt inclusions (MI) is being conducted. The MI chosen for this study are found within olivine grains. MI are thought to be trapped melts of the crystallizing magma preserved by the encapsulating olivine and offer snapshots of the composition of the magma as it evolves. Some MI, in the most Mg-rich part of the olivine of olivine-pyric shergottites, may even be representative of the meteorite parent melt.

  3. Origin of water and mantle-crust interactions on Mars inferred from hydrogen isotopes and volatile element abundances of olivine-hosted melt inclusions of primitive shergottites

    NASA Astrophysics Data System (ADS)

    Usui, Tomohiro; Alexander, Conel M. O'D.; Wang, Jianhua; Simon, Justin I.; Jones, John H.

    2012-12-01

    Volatile elements have influenced the differentiation and eruptive behavior of Martian magmas and played an important role in the evolution of Martian climate and near-surface environments. However, the abundances of volatiles, and in particular the amount of water in the Martian interior, are disputed. A record of volatile reservoirs is contained in primitive Martian basalts (shergottites). Olivine-hosted melt inclusions from a geochemically depleted shergottite (Yamato 980459, representing a very primitive Martian melt) possess undegassed water with a chondritic and Earth-like D/H ratio (δD≤275‰). Based on volatile measurements in these inclusions, the water content of the depleted shergottite mantle is calculated to be 15-47 ppm, which is consistent with the dry mantle hypothesis. In contrast to D/H in the depleted shergottite, melt from an enriched shergottite (Larkman Nunatak 06319), which either formed by melting of an enriched mantle or by assimilation of crust, exhibits an extreme δD of ˜5000‰, indicative of a surface reservoir (e.g., the Martian atmosphere or crustal hydrosphere). These data provide strong evidence that the Martian mantle had retained the primordial low-δD component until at least the time of shergottite formation, and that young Martian basalts assimilated old Martian crust.

  4. Yamato: Bringing the Moon to the Earth ... Again

    NASA Technical Reports Server (NTRS)

    Lam, King; Martinelli, Scott; Patel, Neal; Powell, David; Smith, Brandon

    2008-01-01

    The Yamato mission to the lunar South Pole-Aitken Basin returns samples that enable dating of lunar formation and the lunar bombardment period. The design of the Yamato mission is based on a systems engineering process which takes an advanced consideration of cost and mission risk to give the mission a high probability of success.

  5. Melts of garnet lherzolite: experiments, models and comparison to melts of pyroxenite and carbonated lherzolite

    USGS Publications Warehouse

    Grove, Timothy L.; Holbig, Eva S.; Barr, Jay A.; Till, Christy B.; Krawczynski, Michael J.

    2013-01-01

    Phase equilibrium experiments on a compositionally modified olivine leucitite from the Tibetan plateau have been carried out from 2.2 to 2.8 GPa and 1,380–1,480 °C. The experiments-produced liquids multiply saturated with spinel and garnet lherzolite phase assemblages (olivine, orthopyroxene, clinopyroxene and spinel ± garnet) under nominally anhydrous conditions. These SiO2-undersaturated liquids and published experimental data are utilized to develop a predictive model for garnet lherzolite melting of compositionally variable mantle under anhydrous conditions over the pressure range of 1.9–6 GPa. The model estimates the major element compositions of garnet-saturated melts for a range of mantle lherzolite compositions and predicts the conditions of the spinel to garnet lherzolite phase transition for natural peridotite compositions at above-solidus temperatures and pressures. We compare our predicted garnet lherzolite melts to those of pyroxenite and carbonated lherzolite and develop criteria for distinguishing among melts of these different source types. We also use the model in conjunction with a published predictive model for plagioclase and spinel lherzolite to characterize the differences in major element composition for melts in the plagioclase, spinel and garnet facies and develop tests to distinguish between melts of these three lherzolite facies based on major elements. The model is applied to understand the source materials and conditions of melting for high-K lavas erupted in the Tibetan plateau, basanite–nephelinite lavas erupted early in the evolution of Kilauea volcano, Hawaii, as well as younger tholeiitic to alkali lavas from Kilauea.

  6. Anhydrous Liquid Line of Descent of Yamato 980459 and Evolution of Martian Parental Magmas

    NASA Technical Reports Server (NTRS)

    Rapp, J. F.; Draper, David S.; Mercer, C. M.

    2013-01-01

    Martian basalts represented by the shergottite meteorites reflect derivation from highly depleted mantle sources (high Nd, strong LREE depletions, low fO2)[1-3], with evidence of mixing with a much more enriched and oxidized reservoir, most likely a late-stage product of crystallization of an initial martian magma ocean [3-6]. The martian basaltic meteorites Yamato 980459 (Y98) and QUE 94201 (QUE) have bulk compositions that appear to represent bonafide liquids, rather than products of protracted crystallization. These two meteorites also represent the most primitive and evolved examples of the depleted basaltic shergottite suite. Magmatic liquids serve as effective probes of their source regions, and thus studying the potential relationship between magmas represented by Y98 and QUE can yield important information on the formation and evolution of martian basalts. Although the ages of these meteorites preclude that they are petrogenetically related to each other, they represent the best existing candidates for genuine liquids (other meteorites are suggested to represent liquid compositions, including LAR 06319 [7] and NWA 5789 [8], but only Y98 and QUE have been verified experimentally). They span much of the bulk-compositional range of martian basaltic meteorites, and represent end-member liquid compositions likely to arise from partial melting of the martian mantle. Recent efforts to model Y98-like parent liquid evolution by fractional crystallization using MELTS [6] produced a derivative liquid composition that closely matches QUE bulk composition, although it required a some-what unusual crystallization sequence. Experimental endeavours to verify this result at 1 bar have, however, been inconclusive [9].

  7. Tracking the Depleted Mantle Signature in Melt Inclusions and Residual Glass of Basaltic Martian Shergottites using Secondary Ionization Mass Spectrometry

    NASA Technical Reports Server (NTRS)

    Peters, Timothy J.; Simon, Justin I.; Jones, John H.; Usui, Tomohiro; Economos, Rita C.; Schmitt, Axel K.; McKeegan, Kevin D.

    2013-01-01

    Trace element abundances of depleted shergottite magmas recorded by olivine-hosted melt inclusions (MI) and interstitial mesostasis glass were measured using the Cameca ims-1270 ion microprobe. Two meteorites: Tissint, an olivine-­phyric basaltic shergottite which fell over Morocco July 18th 2001; and the Antarctic meteorite Yamato 980459 (Y98), an olivine-phyric basaltic shergottite with abundant glassy mesostasis have been studied. Chondrite-­normalized REE patterns for MI in Tissint and Y98 are characteristically LREE depleted and, within analytical uncertainty, parallel those of their respective whole rock composition; supporting each meteorite to represent a melt composition that has experienced closed-­system crystallization. REE profiles for mesostasis glass in Y98 lie about an order of magnitude higher than those from the MI; with REE profiles for Tissint MI falling in between. Y98 MI have the highest average Sm/Nd and Y/Ce ratios, reflecting their LREE depletion and further supporting Y98 as one of our best samples to probe the depleted shergotitte mantle. In general, Zr/Nb ratios overlap between Y98 and Tissint MI, Ce/Nb ratios overlap between Y98 MI and mesostasis glass, and Sm/Nd ratios overlap between Y98 mesostasis glass and Tissint MI. These features support similar sources for both, but with subtle geochemical differences that may reflect different melting conditions or fractionation paths during ascent from the mantle. Interestingly, the REE patterns for both Y98 bulk and MI analyses display a flattening of the LREE that suggests a crustal contribution to the Y98 parent melt. This observation has important implications for the origins of depleted and enriched shergottites.

  8. The source crater of martian shergottite meteorites.

    PubMed

    Werner, Stephanie C; Ody, Anouck; Poulet, François

    2014-03-21

    Absolute ages for planetary surfaces are often inferred by crater densities and only indirectly constrained by the ages of meteorites. We show that the <5 million-year-old and 55-km-wide Mojave Crater on Mars is the ejection source for the meteorites classified as shergottites. Shergottites and this crater are linked by their coinciding meteorite ejection ages and the crater formation age and by mineralogical constraints. Because Mojave formed on 4.3 billion-year-old terrain, the original crystallization ages of shergottites are old, as inferred by Pb-Pb isotope ratios, and the much-quoted shergottite ages of <600 million years are due to resetting. Thus, the cratering-based age determination method for Mars is now calibrated in situ, and it shifts the absolute age of the oldest terrains on Mars backward by 200 million years. PMID:24603150

  9. Lu-Hf and Sm-Nd Isotopic Studies of Shergottites and Nakhlites: Implications for Martian Mantle Sources

    NASA Technical Reports Server (NTRS)

    Debaille, V.; Yin, Q.-Z.; Brandon, A. D.; Jacobsen, B.; Treiman, A. H.

    2007-01-01

    We present a new Lu-Hf and Sm-Nd isotope systematics study of four enriched shergottites (Zagami, Shergotty, NWA856 and Los Angeles), and three nakhlites (Nakhla, MIL03346 and Yamato 000593) in order to further understand processes occurring during the early differentiation of Mars and the crystallization of its magma ocean. Two fractions of the terrestrial petrological analogue of nakhlites, the Archaean Theo's flow (Ontario, Canada) were also measured. The coupling of Nd and Hf isotopes provide direct insights on the mineralogy of the melt sources. In contrast to Sm/Nd, Lu/Hf ratios can be very large in minerals such as garnet. Selective partial melting of garnet bearing mantle sources can therefore lead to characteristic Lu/Hf signatures that can be recognized with Hf-176/Hf-177Hf ratios.

  10. The superconducting MHD-propelled ship YAMATO-1

    SciTech Connect

    Sasakawa, Yohei; Takezawa, Setsuo; Sugawara, Yoshinori; Kyotani, Yoshihiro

    1995-04-01

    In 1985 the Ship & Ocean Foundation (SOF) created a committee under the chairmanship of Mr. Yohei Sasakawa, Former President of the Ship & Ocean Foundation, and began researches into superconducting magnetohydrodynamic (MHD) ship propulsion. In 1989 SOF set to construction of a experimental ship on the basis of theoretical and experimental researches pursued until then. The experimental ship named YAMATO-1 became the world`s first superconducting MHD-propelled ship on her trial runs in June 1992. This paper describes the outline of the YAMATO-1 and sea trial test results.

  11. Solar proton produced neon in shergottite meteorites

    NASA Technical Reports Server (NTRS)

    Garrison, D. H.; Rao, M. N.; Bogard, D. D.

    1994-01-01

    Cosmogenic radionuclides produced by near-surface, nuclear interactions of energetic solar protons (approx. 10-100 MeV) were reported in several lunar rocks and a very small meteorites. We recently documented the existence and isotopic compositions of solar-produced (SCR) Ne in two lunar rocks. Here we present the first documented evidence for SCR Ne in a meteorite, ALH77005, which was reported to contain SCR radionuclides. Examination of literature data for other shergottites suggests that they may also contain a SCR Ne component. The existence of SCR Ne in shergottites may be related to a Martian origin.

  12. Geochemistry of intermediate olivine-phyric shergottite Northwest Africa 6234, with similarities to basaltic shergottite Northwest Africa 480 and olivine-phyric shergottite Northwest Africa 2990

    NASA Astrophysics Data System (ADS)

    Filiberto, Justin; Chin, Emily; Day, James M. D.; Franchi, Ian A.; Greenwood, Richard C.; Gross, Juliane; Penniston-Dorland, Sarah C.; Schwenzer, Susanne P.; Treiman, Allan H.

    2012-08-01

    The newly found meteorite Northwest Africa 6234 (NWA 6234) is an olivine (ol)-phyric shergottite that is thought, based on texture and mineralogy, to be paired with Martian shergottite meteorites NWA 2990, 5960, and 6710. We report bulk-rock major- and trace-element abundances (including Li), abundances of highly siderophile elements, Re-Os isotope systematics, oxygen isotope ratios, and the lithium isotope ratio for NWA 6234. NWA 6234 is classified as a Martian shergottite, based on its oxygen isotope ratios, bulk composition, and bulk element abundance ratios, Fe/Mn, Al/Ti, and Na/Al. The Li concentration and δ7Li value of NWA 6234 are similar to that of basaltic shergottites Zagami and Shergotty. The rare earth element (REE) pattern for NWA 6234 shows a depletion in the light REE (La-Nd) compared with the heavy REE (Sm-Lu), but not as extreme as the known "depleted" shergottites. Thus, NWA 6234 is suggested to belong to a new category of shergottite that is geochemically "intermediate" in incompatible elements. The only other basaltic or ol-phyric shergottite with a similar "intermediate" character is the basaltic shergottite NWA 480. Rhenium-osmium isotope systematics are consistent with this intermediate character, assuming a crystallization age of 180 Ma. We conclude that NWA 6234 represents an intermediate compositional group between enriched and depleted shergottites and offers new insights into the nature of mantle differentiation and mixing among mantle reservoirs in Mars.

  13. Basaltic Shergottite NWA 856: Differentiation of a Martian Magma

    NASA Technical Reports Server (NTRS)

    Ferdous, J.; Brandon, A. D.; Peslier, A. H.; Pirotte, Z.

    2016-01-01

    NWA 856 or Djel Ibone, is a basaltic shergottite discovered as a single stone of 320 g in South Morocco in April, 2001. This meteorite is fresh, i.e. shows minimal terrestrial weathering for a desert find. No shergottite discovered in North Africa can be paired with NWA 856. The purpose of this study is to constrain its crystallization history using textural observations, crystallization sequence modeling and in-situ trace element analysis in order to understand differentiation in shergottite magmatic systems.

  14. Shock Metamorphism of the Dhofar 378 Basaltic Shergottite

    NASA Technical Reports Server (NTRS)

    Mikouchi, T.; McKay, G.

    2006-01-01

    Shock metamorphism is one of the most fundamental processes in the history of Martian meteorites, especially shergottites, which affect their mineralogy and chronology. The formation of "maskelynite" from plagioclase and shock melts is such major mineralogical effects. Dhofar 378 is one of the recently found desert shergottites that is mainly composed of plagioclase and pyroxene. This shergottite is important because of its highly shocked nature and unique plagioclase texture, and thus has a great potential for assessing a "shock" age of shergottites. We have been working on a combined study of mineralogy and chronology of the same rock chip of Dhofar 378. This abstract reports its mineralogical part.

  15. New Titanium Monosulfide Mineral Phase in Yamato 691 Enstatite Chondrite

    NASA Technical Reports Server (NTRS)

    Nakamura-Messenger, K; Clemett, S. J.; Rubin, A. E.; Choi, B.-G.; Zhang, S.; Rahman, Z.; Oikawa, K.; Keller, L. P.

    2011-01-01

    Yamato 691, an EH3 enstatite chondrite, was among the first meteorites discovered by chance in Antarctica by the Japanese Antarctic Research Expedition (JARE) team in 1969. This discovery led to follow-up searches for meteorites in Antarctica [1]. These international searches have been very successful recovering over 40,000 total specimens (and still counting), including martian and lunar meteorites. Titanium is partly chalcophile in enstatite-rich meteorites. Previous occurrences of Ti-bearing sulfides include troilite, daubrelite and ferroan alabandite in enstatite chondrites and aubrites [2], and heideite with 28.5 wt% Ti in the Bustee aubrite [3]. Here we report a new mineral from Yamato 691, ideally stoichiometric TiS, titanium monosulfide, a simple two-element mineral phase, yet with a very unique crystal structure that, to our knowledge, has not been observed previously in nature.

  16. Amino acids in the Yamato carbonaceous chrondrite from Antarctica

    NASA Technical Reports Server (NTRS)

    Shimoyama, A.; Ponnamperuma, C.; Yanai, K.

    1979-01-01

    Evidence for the presence of amino acids of extraterrestrial origin in the Antarctic Yamato carbonaceous chrondrite is presented. Hydrolyzed and nonhydrolyzed water-extracted amino acid samples from exterior, middle and interior portions of the meteorite were analyzed by an amino acid analyzer and by gas chromatography of N-TFA-isopropyl amino acid derivatives. Nine protein and six nonprotein amino acids were detected in the meteorite at abundances between 34 and less than one nmole/g, with equal amounts in interior and exterior portions. Nearly equal abundances of the D and L enantiomers of alanine, aspartic acid and glutamic acid were found, indicating the abiotic, therefore extraterrestrial, origin of the amino acids. The Antarctic environment and the uniformity of protein amino acid abundances are discussed as evidence against the racemization of terrestrially acquired amino acids, and similarities between Yamato amino acid compositions and the amino acid compositions of the Murchison and Murray type II carbonaceous chrondrites are indicated.

  17. A More Reduced Mantle Source for Enriched Shergottites; Insights from the Olivine-Phyric Shergottite Lar 06319

    NASA Technical Reports Server (NTRS)

    Peslier, A. H.; Hnatyshin, D.; Herd, C. D. K.; Walton, E. L.; Brandon, A. D.; Lapen, T. J.; Shafer, J.

    2010-01-01

    A detailed petrographic study of melt inclusions and Cr-Fe-Ti oxides of LAR 06319 leads to two main conclusions: 1) this enriched oxidized olivine- phyric shergottite represents nearly continuous crystallization of a basaltic shergottite melt, 2) the melt became more oxidized during differentiation. The first crystallized mineral assemblages record the oxygen fugacity which is closest to that of the melt s mantle source, and which is lower than generally attributed to the enriched shergottite group.

  18. The age of the martian meteorite Northwest Africa 1195 and the differentiation history of the shergottites

    SciTech Connect

    Symes, S; Borg, L; Shearer, C; Irving, A

    2007-04-05

    Samarium-neodymium isotopic analyses of unleached and acid-leached mineral fractions from the recently identified olivine-bearing shergottite Northwest Africa 1195 yield a crystallization age of 348 {+-} 19 Ma and an {var_epsilon}{sub Nd}{sup 143} value of +40.1 {+-} 1.3. Maskelynite fractions do not lie on the Sm-Nd isochron and appear to contain a martian surface component with low {sup 147}Sm/{sup 144}Nd and {sup 143}Nd/{sup 144}Nd ratios that was added during shock. The Rb-Sr system is disturbed and does not yield an isochron. Terrestrial Sr appears to have affected all of the mineral fractions, although a maximum initial {sup 87}Sr/{sup 86}Sr ratio of 0.701614 {+-} 16 is estimated by passing a 348 Ma reference isochron through the maskelynite fraction that is least affected by contamination. The high initial {var_epsilon}{sub Nd}{sup 143} value and the low initial {sup 87}Sr/{sup 86}Sr ratio, combined with the geologically young crystallization age, indicate that Northwest Africa 1195 is derived from a source region characterized by a long-term incompatible element depletion. The age and initial Sr and Nd isotopic compositions of Northwest Africa 1195 are very similar to those of Queen Alexandra Range 94201, indicating these samples were derived from source regions with nearly identical Sr-Nd isotopic systematics. These similarities suggest that these two meteorites share a close petrogenetic relationship and might have been erupted from a common volcano. The meteorites Yamato 980459, Dar al Gani 476, Sayh al Uhaymir 005/008, and Dhofar 019 also have relatively old ages between 474-575 Ma and trace element and/or isotopic systematics that are indicative of derivation from incompatible-element-depleted sources. This suggests that the oldest group of meteorites is more closely related to one another than they are to the younger meteorites that are derived from less incompatible-element-depleted sources. Closed-system fractional crystallization of this suite of

  19. Northwest Africa 5298: A Basaltic Shergottite

    NASA Technical Reports Server (NTRS)

    Hui, Hejiu; Peslier, Anne; Lapen, Thomas J.; Brandon, Alan; Shafer, John

    2009-01-01

    NWA 5298 is a single 445 g meteorite found near Bir Gandouz, Morocco in March 2008 [1]. This rock has a brown exterior weathered surface instead of a fusion crust and the interior is composed of green mineral grains with interstitial dark patches containing small vesicles and shock melts [1]. This meteorite is classified as a basaltic shergottite [2]. A petrologic study of this Martian meteorite is being carried out with electron microprobe analysis and soon trace element analyses by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Oxygen fugacity is calculated from Fe-Ti oxides pairs in the sample. The data from this study constrains the petrogenesis of basaltic shergottites.

  20. Volatile compounds in shergottite and nakhlite meteorites

    NASA Technical Reports Server (NTRS)

    Gooding, James L.; Aggrey, Kwesi E.; Muenow, David W.

    1990-01-01

    Since discovery of apparent carbonate carbon in Nakhla, significant evidence has accumulated for occurrence of volatile compounds in shergotties and nakhlites. Results are presented from a study of volatile compounds in three shergottites, one nakhlite, and three eucrite control samples. Shergotties ALHA77005, EETA79001, and Shergotty, and the nakhlite Nakhla, all contain oxidized sulfur (sulfate) of preterrestrial origin; sulfur oxidation is most complete in EETA79001/Lith-C. Significant bulk carbonate was confirmed in Nakhla and trace carbonate was substantiated for EETA79001, all of which appears to be preterrestrial in origin. Chlorine covaries with oxidized sulfur, whereas carbonate and sulfate are inversely related. These volatile compounds were probably formed in a highly oxidizing, aqueous environment sometime in the late stage histories of the rocks that are now represented as meteorites. They are consistent with the hypothesis that shergottite and nakhlite meteorites originated on Mars and that Mars has supported aqueous geochemistry during its history.

  1. The case for old basaltic shergottites

    NASA Astrophysics Data System (ADS)

    Bouvier, Audrey; Blichert-Toft, Janne; Vervoort, Jeffrey D.; Gillet, Philippe; Albarède, Francis

    2008-02-01

    The crystallization age of shergottites is currently not agreed upon. Although mineral 87Rb- 87Sr, 147Sm- 143Nd, 176Lu- 176Hf, and U-Pb isochrons all give very young ages, typically in the range of 160-180 Ma, 207Pb- 206Pb data support a much older crystallization age at 4.1 Ga, which is consistent with published whole-rock 87Rb- 87Sr data on basaltic shergottites. Different isotopic systems present different complexities, but crater-counting chronology, which shows that a substantial fraction of the Martian surface was resurfaced during the late heavy bombardment, is in favor of an old Martian lithosphere with ages in accordance with Pb-Pb and Rb-Sr isotopic data. A ˜ 4.1 Ga Pb-Pb age of shergottites also agrees with the 142Nd and 182W anomalies found in these rocks and concur with the presence of an actively convecting mantle during the first 500 Myr of the planet's history. We here present new Sm-Nd, Lu-Hf, and Pb-Pb mineral isochrons for the basaltic shergottites Shergotty and Los Angeles complementing our previous results on Zagami [Bouvier A., Blichert-Toft J., Vervoort J.D. and Albarède F. (2005). The age of SNC meteorites and the antiquity of the Martian surface, Earth Planet. Sci. Lett. 240, 221-233]. The internal 147Sm- 143Nd and 176Lu- 176Hf isochrons give young ages of, respectively, 172 ± 40 (MSWD = 2.0) and 188 ± 91 (MSWD = 3.1) for Shergotty, and 181 ± 13 (MSWD = 0.14) and 159 ± 42 (MSWD = 0.01) for Los Angeles. In contrast, the Pb isotope compositions of the leached whole-rock fragments and maskelynite separates of Shergotty and Los Angeles fall on the whole-rock isochron previously established for Zagami and other shergottite samples and collectively yield a Pb-Pb age of 4050 ± 70 Ma for the crystallization of the basaltic shergottite suite. The contrast between the ˜ 170 Ma ages of internal isochrons and the 4.1 Ga age supported by Pb-Pb and 87Rb- 87Sr on whole-rocks simply reflects that the younger age dates the perturbation of a suite of

  2. Lherzolite, anorthosite, gabbro, and basalt dredged from the Mid-Indian Ocean Ridge

    USGS Publications Warehouse

    Engel, C.G.; Fisher, R.L.

    1969-01-01

    The Central Indian Ridge is mantled with flows of low-potassium basalt of uniform composition. Gabbro, anorthosite, and garnet-bearing lherzolite are exposed in cross fractures, and lherzolite is the bedrock at the center of the ridge. The lherzolites are upper-mantle rock exposed by faulting.

  3. Geochemistry of Intermediate Olivine-Phyric Shergottite Northwest Africa 6234

    NASA Astrophysics Data System (ADS)

    Filiberto, J.; Chin, E.; Day, J. M. D.; Gross, J.; Penniston-Dorland, S. C.; Schwenzer, S. P.; Treiman, A. H.

    2012-03-01

    Here we present major- and trace-element geochemistry, Li-isotope composition and abundance, and Re-Os isotope and highly siderophile element abundance data for the ol-phyric shergottite Northwest Africa 6234.

  4. Terrestrial C-14 age of the Antarctic shergottite, EETA 79001

    NASA Technical Reports Server (NTRS)

    Jull, A. J. T.; Donahue, D. J.

    1988-01-01

    The terrestrial age of the Elephant Moraine shergottite EETA 79001 (lithology A) has been determined from measurement of its cosmogenic C-14 content as 12 +/- 2 kyr. The results on saturated and blank samples of 1 g or less are also discussed. The age calculated for EETA 79001 is compared to exposure and terrestrial ages of other shergottites in the light of possible origins of these meteorites on Mars.

  5. Some phase equilibrium systematics of lherzolite melting: I

    NASA Astrophysics Data System (ADS)

    Longhi, John

    2002-03-01

    New piston-cylinder experiments constrain the compositions of a series of synthetic picritic liquids that are in equilibrium with forsteritic olivine, orthopyroxene, clinopyroxene, and garnet or spinel from 2.4 to 3.4 Gpa. Mass balance calculations show that two of the liquid + crystal assemblages are consistent with those expected by 4.4 and 1.6 wt % anhydrous partial melting of a peridotite generally similar in composition to estimates of depleted upper mantle (DPUM). The liquids in these runs contain <=2.0 wt % Na2O. Lherzolitic liquids with higher concentrations of Na2O have negative mass balance coefficients, regardless of Mg', implying that there is a limit of ~2 wt % Na2O in anhydrous partial melts of peridotites with ~0.3 wt % bulk Na2O in the upper garnet-lherzolite stability field. Examination of liquidus equilibria in the NCMAS system demonstrates that coupling of Na2O and SiO2 concentrations in liquids saturated with lherzolite assemblages permits high-Na2O, high-SiO2 melts at pressures ~1.0 GPa, whereas only high-Na2O, low-SiO2 melts are possible in the garnet-lherzolite stability field. Because the bulk partition coefficient for Na2O increases with pressure, the concentration of Na2O in batch melts of the same percent will necessarily decrease with pressure. Calculations of low-degree anhydrous melting of DPUM with a revised melting model, BATCH, indicate that the Na2O concentration decreases with increasing pressure more rapidly than in previous models. Thus, for example, 1% melting of lherzolite with Na2O bulk concentration typical of estimated terrestrial mantle (~0.3 wt %), can produce a liquid with ~6 wt % Na2O at 1.0 GPa but only ~2% Na2O at 3.0 Gpa. In calculated melts of the DPUM and PUM compositions at 1.0 Gpa, the TiO2 concentration decreases between 10 and 1% melting in response to an increase inDTiO2cpx, consistent reported experimental observations. The increase in DTiO2cpx appears to be a response to increasing alkalis in the melt

  6. The Origin and Impact History of Lunar Meteorite Yamato 86032

    NASA Technical Reports Server (NTRS)

    Yamaguchi, A.; Takeda, H.; Nyquist, L. E.; Bogard, D. D.; Ebihara, M.; Karouji, Y.

    2004-01-01

    Yamato (Y) 86032 is a feldspathic lunar highland breccia having some characteristics of regolith breccia. The absence of KREEP components in the matrix in Y86032 indicates that these meteorites came from a long distance from Mare Imbrium, perhaps from the far-side of the moon. One ferroan anorthosite (FAN) clast in Y86032 has a very old Ar-Ar age of approximately 4.35-4.4 Ga. The negative Nd of this clast may suggest a direct link with the primordial magma ocean. The facts indicate that Y86032 contains components derived from a protolith of the original lunar crust. Detailed petrologic characterization of each component in this breccia is essential to understand the early impact history and origin of the lunar highland crust. We made a large slab (5.2 x 3.6 cm x 3-5 mm) of Y86032 to better understand the relationship of various lithologies and their petrologic origin.

  7. Jarosite in the Shergottite Que 94201

    NASA Technical Reports Server (NTRS)

    Ross, D. K.; Ito, M.; Rao, M. N.; Hervig, R.; Williams, L. B.; Nyquist, Laurence E.; Peslier, A.

    2010-01-01

    Veins of the hydroxylated, potassium ferric sulfate mineral jarosite - KFe3(SO4)2(OH)6 - have been identified in the martian meteorite Queen Alexandra Range (QUE) 94201. Iron potassium sulfate had been reported in QUE 94201 by Wentworth and Gooding. Jarosite has been reported in other Martian meteorites - Roberts Massif (RBT) 04262, Miller Range (MIL) 03346, and Yamato 000593 - and it has been identified on the Martian surface by Moessbauer spectroscopy. Given the presence of jarosite on Mars, and the burgeoning interest in water-rock interactions on Mars, the question arises whether jarosite in Martian meteorites is formed by aqueous alteration on Mars, or in Antarctica. Hydrogen isotopes are potentially sensitive indicators of the site of formation or last equilibration of hydrous alteration minerals, because of the large difference between D/H ratio of the Martian atmosphere (and also presumably the cryosphere) and terrestrial hydrogen. The Martian atmospheric delta D(sub SMOW) ratio is approximately +4200%o, igneous minerals with substantial hydrogen (phosphates) have high D, +2000%o to +4700%o versus terrestrial waters with approximately 480%o to +130%o. The crystal chemistry and structure of jarosite are reviewed in Papi ke et al. Here we report hydrogen isotopes measured in jarosite in QUE 94201 by ion microprobe, and also report on the major element composition of jarosite measured by electron microprobe.

  8. Thermobarometry for spinel lherzolite xenoliths in alkali basalts

    NASA Astrophysics Data System (ADS)

    Ozawa, Kazuhito; Youbi, Nasrrddine; Boumehdi, Moulay Ahmed; Nagahara, Hiroko

    2016-04-01

    Application of geothermobarometers to peridotite xenoliths has been providing very useful information on thermal and chemical structure of lithospheric or asthenospheric mantle at the time of almost instantaneous sampling by the host magmas, based on which various thermal (e.g., McKenzie et al., 2005), chemical (e.g., Griffin et al., 2003), and rheological (e.g., Ave Lallemant et al., 1980) models of lithosphere have been constructed. Geothermobarometry for garnet or plagioclase-bearing lithologies provide accurate pressure estimation, but this is not the case for the spinel peridotites, which are frequently sampled from Phanerozoic provinces in various tectonic environments (Nixon and Davies, 1987). There are several geobarometers proposed for spinel lherzolite, such as single pyroxene geothermobarometer (Mercier, 1980) and geothermobarometer based on Ca exchange between olivine and clinopyroxene (Köhler and Brey, 1990), but they have essential problems and it is usually believed that appropriated barometers do not exist for spinel lherzolites (O'Reilly et al., 1997; Medaris et al., 1999). It is thus imperative to develop reliable barometry for spinel peridotite xenoliths. We have developed barometry for spinel peridotite xenoliths by exploiting small differences in pressure dependence in relevant reactions, whose calibration was made through careful evaluation of volume changes of the reactions. This is augmented with higher levels of care in application of barometer by choosing mineral domains and their chemical components that are in equilibrium as close as possible. This is necessary because such barometry is very sensitive to changes in chemical composition induced by transient state of the system possibly owing to pressure and temperature changes as well as chemical modification, forming chemical heterogeneity or zoning frequently reported from various mantle xenoliths (Smith, 1999). Thus very carful treatment of heterogeneity, which might be trivial for

  9. Lherzolite, anorthosite, gabbro, and basalt dredged from the mid-Indian ocean ridge.

    PubMed

    Engel, C G; Fisher, R L

    1969-11-28

    The Central Indian Ridge is mantled with flows of low-potassium basalt of uniform composition. Gabbro, anorthosite, and garnet-bearing lherzolite are exposed in cross fractures, and lherzolite is the bedrock at the center of the ridge. The Iherzolites are upper-mantle rock exposed by faulting. PMID:17775570

  10. Crystallization Age of NWA 1460 Shergottite: Paradox Revisited

    NASA Technical Reports Server (NTRS)

    Nyquist, L. E.; Shih, C-Y.; Reese, Y. D.; Irving, A. J.

    2004-01-01

    We have determined the Rb-Sr age of basaltic shergottite NWA 1460 to be 312 +/- 3 Ma, and the Sm-Nd age to be 352 +/- 30 Ma. The initial Sr and Nd isotopic compositions of NWA 1460 suggest it is an earlier melting product of a Martian mantle source region similar to those of the Iherzolitic shergottites and basaltic shergottite EETA79001, lithology B. The new ages of NWA 1460 and other recently analyzed Martian meteorites leads us to reexamine the paradox that most of the Martian meteorites appear to be younger from the majority of the Martian surface. This paradox continues to pose a challenge to determining a reliable Martian chronology.

  11. Lunar meteorite Yamato-86032 - Mineralogical, petrological, and geochemical studies

    NASA Technical Reports Server (NTRS)

    Koeberl, Christian; Kurat, Gero; Brandstaetter, Franz

    1990-01-01

    Yamato-86032 is a shock-lithified anorthositic fragmental breccia. It consists mainly of highly feldspathic meta-breccias and meta-meltrocks and possibly contains a small contribution from mare lithologies, but there is no indication of a KREEP component. In many respects Y-86032 is similar to the previously described lunar meteorites Y-82192/3, but there are some notable differences. We have analyzed about 40 major and trace elements in bulk matrix, impact melt, and clast samples from two chips of Y-86032. The abundances of most lithophile and incompatible elements are lower in Y-86032 than in Y-82192 (which contains very low abundances compared to normal lunar highland rocks). The REE abundances are comparable to those of Y-82192. The elements Sc, Cr, Mn, Fe and Co have significantly lower abundances than in Y-82192, and the siderophile element pattern is also different. Since cosmic ray exposure data indicate pairing of Y-86032 with Y-82192/3, the source region for these meteorites on the moon must have been fairly heterogeneous.

  12. Lead Isotopes in Olivine-Phyric Shergottite Tissint: Implications for the Geochemical Evolution of the Shergottite Source Mantle

    NASA Technical Reports Server (NTRS)

    Moriwaki, R.; Usui, T.; Simon, J. I.; Jones, J. H.; Yokoyama, T.

    2015-01-01

    Geochemically-depleted shergottites are basaltic rocks derived from a martian mantle source reservoir. Geochemical evolution of the martian mantle has been investigated mainly based on the Rb-Sr, Sm-Nd, and Lu-Hf isotope systematics of the shergottites [1]. Although potentially informative, U-Th- Pb isotope systematics have been limited because of difficulties in interpreting the analyses of depleted meteorite samples that are more susceptible to the effects of near-surface processes and terrestrial contamination. This study conducts a 5-step sequential acid leaching experiment of the first witnessed fall of the geochemically-depleted olivinephyric shergottite Tissint to minimize the effect of low temperature distrubence. Trace element analyses of the Tissint acid residue (mostly pyroxene) indicate that Pb isotope compositions of the residue do not contain either a martian surface or terrestrial component, but represent the Tissint magma source [2]. The residue has relatively unradiogenic initial Pb isotopic compositions (e.g., 206Pb/204Pb = 10.8136) that fall within the Pb isotope space of other geochemically-depleted shergottites. An initial µ-value (238U/204Pb = 1.5) of Tissint at the time of crystallization (472 Ma [3]) is similar to a time-integrated mu- value (1.72 at 472 Ma) of the Tissint source mantle calculated based on the two-stage mantle evolution model [1]. On the other hand, the other geochemically-depleted shergottites (e.g., QUE 94201 [4]) have initial µ-values of their parental magmas distinctly lower than those of their modeled source mantle. These results suggest that only Tissint potentially reflects the geochemical signature of the shergottite mantle source that originated from cumulates of the martian magma ocean

  13. Crystallization kinetics of olivine-phyric shergottites

    NASA Astrophysics Data System (ADS)

    Ennis, Megan E.; McSween, Harry Y.

    2014-08-01

    Crystal size distribution (CSD) and spatial distribution pattern (SDP) analyses are applied to the early crystallizing phases, olivine and pyroxene, in olivine-phyric shergottites (Elephant moraine [EET] 79001A, Dar al Gani [DaG] 476, and dhofar [Dho] 019) from each sampling locality inferred from Mars ejection ages. Trace element zonation patterns (P and Cr) in olivine are also used to characterize the crystallization history of these Martian basalts. Previously reported 2-D CSDs for these meteorites are re-evaluated using a newer stereographically corrected methodology. Kinks in the olivine CSD plots suggest several populations that crystallized under different conditions. CSDs for pyroxene in DaG 476 and EET 79001A reveal single populations that grew under steady-state conditions; pyroxenes in Dho 019 were too intergrown for CSD analysis. Magma chamber residence times of several days for small grains to several months for olivine megacrysts are calculated using the CSD slopes and growth rates inferred from previous experimental data. Phosphorus imaging in olivines in DaG 476 and Dho 019 indicate rapid growth of skeletal, sector-zoned, or patchy cores, probably in response to delayed nucleation, followed by slow growth, and finally rapid dendritic growth with back-filling to form oscillatory zoning in rims. SPD analyses indicate that olivine and pyroxene crystals grew or accumulated in clusters rather than as randomly distributed grains. These data reveal complex solidification histories for Martian basalts, and are generally consistent with the formation at depth of olivine megacryst cores, which were entrained in ascending magmas that crystallized pyroxenes, small olivines, and oscillatory rims on megacrysts.

  14. Putative Indigenous Carbon-Bearing Alteration Features in Martian Meteorite Yamato 000593

    PubMed Central

    Gibson, Everett K.; Thomas-Keprta, Kathie L.; Clemett, Simon J.; McKay, David S.

    2014-01-01

    Abstract We report the first observation of indigenous carbonaceous matter in the martian meteorite Yamato 000593. The carbonaceous phases are heterogeneously distributed within secondary iddingsite alteration veins and present in a range of morphologies including areas composed of carbon-rich spheroidal assemblages encased in multiple layers of iddingsite. We also observed microtubular features emanating from iddingsite veins penetrating into the host olivine comparable in shape to those interpreted to have formed by bioerosion in terrestrial basalts. Key Words: Meteorite—Yamato 000593—Mars—Carbon. Astrobiology 14, 170–181. PMID:24552234

  15. Provenance and Concentration of Water in the Shergottite Mantle

    NASA Technical Reports Server (NTRS)

    Jones, J. H.; Usui, T.; Alexander, C. M. O'D.; Simon, J. I.; Wang, J.

    2012-01-01

    The water content of the martian mantle is controversial. In particular, the role of water in the petrogenesis of the shergottites has been much debated. Although the shergottites, collectively, contain very little water [e.g., 1,2], some experiments have been interpreted to show that percent levels of water are required for the petrogenesis of shergottites such as Shergotty and Zagami [3]. In this latter interpretation, the general paucity of water in the shergottites and their constituent minerals is attributed to late-stage degassing. Y980459 (Y98) is a very primitive, perhaps even parental, martian basalt, with a one-bar liquidus temperature of approx.1400 C. Olivine is the liquidus phase, and olivine core compositions are in equilibrium with the bulk rock [e.g., 4]. Petrogenetically, therefore, Y98 has had a rather simple history and can potentially help constrain the role of water in martian igneous processes. In particular, once trapped, melt inclusions should not be affected by subsequent degassing.

  16. New constraints on the formation of shergottite Elephant Moraine 79001 lithology A

    NASA Astrophysics Data System (ADS)

    Liu, Yang; Balta, J. Brian; Goodrich, Cyrena A.; McSween, Harry Y.; Taylor, Lawrence A.

    2013-05-01

    Previous studies of Elephant Moraine (EET) 79001 disagreed upon the nature of the magnesian olivine and orthopyroxene grains, and generally considered the formation of EET 79001 at low pressure conditions. New observations on mineral associations, and trace-element abundances of olivine-hosted melt inclusions, in lithology A (EET-A) of EET 79001 lead to new constraints on the formation of this meteorite. The abundances and chondrite-normalized REE pattern of the average melt inclusions in olivine of Mg# 75-61 are similar to those of the bulk-rock composition of lithology A, suggesting that the Mg# <77 olivines are phenocrysts. We also report the widespread occurrence of round orthopyroxene (En78.9-77.9Wo2.2-2.5) inclusions in disequilibrium contact with their olivine hosts (Mg# 73-68). Compositions of these inclusions are similar to xenocrystic cores (Mg# ⩾77; Wo ⩽4) in pyroxene megacrysts. These observations indicate that orthopyroxene xenocrysts were being resorbed while Mg# 77-73 olivine was crystallizing. Combined, these observations suggest that only small portions of the megacrysts are xenocrystic, namely orthopyroxene of Mg# ⩾77 and Wo ⩽4, and possibly also olivine of Mg# ⩾77. The volume percentages of the xenocrystic materials in the rock are small (⩽1 vol.% for each mineral). Compositions of the xenocrystic minerals are similar to cores of megacrysts in olivine-phyric shergottite Yamato (Y) 980459 and Northwest Africa (NWA) 5789. Considering the small fraction of xenocrysts and the similarity between REE abundances of the early-trapped melt and those in bulk EET-A, we re-evaluated the possibility that the bulk-rock composition of EET-A is close to that of its parent melt. Results of pMELTS modeling indicate that polybaric crystallization of the EET-A bulk composition (corrected by removal of xenocryst material) can reproduce the crystallization sequence of EET-A, in contrast to the conclusions of previous workers. We estimate that the EET

  17. Solubility of Sulfur in Shergottitic Silicate Melts Up to 0.8 GPA: Implications for S Contents of Shergottites

    NASA Technical Reports Server (NTRS)

    Righter, K.; Pando, K.M.; Danielson, L.

    2009-01-01

    Shergottites have high S contents (1300 to 4600 ppm; [1]), but it is unclear if they are sulfide saturated or under-saturated. This issue has fundamental implications for determining the long term S budget of the martian surface and atmosphere (from mantle degassing), as well as evolution of the highly siderophile elements (HSE) Au, Pd, Pt, Re, Rh, Ru, Ir, and Os, since concentrations of the latter are controlled by sulfide stability. Resolution of sulfide saturation depends upon temperature, pressure, oxygen fugacity (and FeO), and magma composition [2]. Expressions derived from experimental studies allow prediction of S contents, though so far they are not calibrated for shergottitic liquids [3-5]. We have carried out new experiments designed to test current S saturation models, and then show that existing calibrations are not suitable for high FeO and low Al2O3 compositions characteristic of shergottitic liquids. The new results show that existing models underpredict S contents of sulfide saturated shergottitic liquids by a factor of 2.

  18. An Experimental Investigation of the Shergottite NWA 6162

    NASA Technical Reports Server (NTRS)

    Barnett, R. Gaylen; Jones, John H.; Draper, David S.; Le, Loan H.

    2012-01-01

    The Martian meteorite North West Africa 6162 (NWA 6162) is a shergottite found in Morocco in 2010. The meteorite has large olivine crystals with Mg-depleted rims as low as FO(sub 65) and Mg-rich cores of up to FO(sub 74). It is similar both in appearance and composition to another shergottite, SaU 005. Our objective is to determine if NWA 6162 represents a liquid or if it is a product of olivine accumulation. Olivine accumulation would leave the parent melt Mg-depleted and the complementary olivine cumulates would be Mg-enriched. Therefore, if NWA 6162 is a partial cumulate we would expect that liquidus olivines grown from this bulk composition would be more magnesium than olivines in the natural sample.

  19. AR-39-AR-40 "Age" of Basaltic Shergottite NWA-3171

    NASA Technical Reports Server (NTRS)

    Bogard, Donald D.; Park, Jisun

    2007-01-01

    North-West-Africa 3171 is a 506 g, relatively fresh appearing, basaltic shergottite with similarities to Zagami and Shergotty, but not obviously paired with any of the other known African basaltic shergottites. Its exposure age has the range of 2.5-3.1 Myr , similar to those of Zagami and Shergotty. We made AR-39-AR-40 analyses of a "plagioclase" (now shock-converted to maskelynite) separate and of a glass hand-picked from a vein connected to shock melt pockets.. Plagioclase was separated using its low magnetic susceptibility and then heavy liquid with density of <2.85 g/cm(exp 3). The AR-39-AR-40 age spectrum of NWA-317 1 plag displays a rise in age over 20-100% of the 39Ar release, from 0.24 Gyr to 0.27 Gy.

  20. The harzburgites-lherzolite cycle: depletion and refertilization processes

    NASA Astrophysics Data System (ADS)

    Dijkstra, A. H.

    2011-12-01

    Lherzolites or clinopyroxene-rich harzburgites sampled at the ocean floor are now generally interpreted as refractory harzburgites refertilized by melt-rock reaction or melt impregnation at the spreading center, rather than as relatively undepleted bulk upper mantle. The key evidence for a melt refertilization origin is often textural. Critically, the refertilization can mask the underlying very refractory character: oceanic peridotites prior to melt refertilization at the ridge are often too refractory to be simple mantle residues of bulk upper mantle that was melted at the ridge. This suggests that the upper mantle contains large domains that record prior melting histories. This is supported by ancient rhenium-depletion ages that are common in oceanic peridotites. In this presentation, I will discuss some key examples (e.g., Macquarie Island [1], Pindos, Totalp, Lanzarote) of refertilized oceanic peridotites, which all have recorded previous, ancient depletions. I will show the textural and geochemical evidence for melt refertilization. It has often been assumed that melt refertilization occurs by interaction with mantle melts. However, there is now evidence for melt refertilization through a reaction with eclogite-derived melts, probably at the base of the melting column underneath the ridge system. These eclogitic mantle heterogeneities themselves do not normally survive the melting underneath the spreading center, but their isotopic signature can be recognized in the reacted peridotites. In summary, we have moved away from the idea that oceanic mantle rocks are simple melting residues of homogeneous bulk upper mantle. The picture that emerges is a rich and complex one, suggesting that oceanic mantle rocks record dynamic histories of melting and refertilization. In particular, the melting event in refertilized peridotites can be much older than the age of the ridge system at which they are sampled. Many oceanic peridotites contain evidence for a Mesoproterozoic

  1. APXS ANALYSES OF BOUNCE ROCK: THE FIRST SHERGOTTITE ON MARS

    NASA Technical Reports Server (NTRS)

    Ming, Douglas W.; Zipfel, J.; Anderson, R.; Brueckner, J.; Clark, B. C.; Dreibus, G.; Economou, T.; Gellert, R.; Lugmair, G. W.; Klingelhoefer, G.

    2005-01-01

    During the MER Mission, an isolated rock at Meridiani Planum was analyzed by the Athena instrument suite [1]. Remote sensing instruments noticed its distinct appearance. Two areas on the untreated rock surface and one area that was abraded with the Rock Abrasion Tool were analyzed by Microscopic Imager, Mossbauer Mimos II [2], and Alpha Particle X-ray Spectrometer (APXS). Results of all analyses revealed a close relationship of this rock with known basaltic shergottites.

  2. Shergottite Impact Melt Glasses Contain Soil from Martian Uplands

    NASA Technical Reports Server (NTRS)

    Rao, M. N.; McKay, D. S.

    2002-01-01

    Martian meteorite (shergottite) impact melt glasses that contain high concentrations of martian atmospheric noble gases and show significant variations in Sr-87/Sr-86 isotopic ratios are likely to contain Martian surface fines mixed with coarser regolith materials. The mixed soil constituents were molten due to shock at the time of meteoroid impact near the Martian surface and the molten glass got incorporated into the voids and cracks in some shergottite meteorites. Earlier, Rao et al. found large enrichments of sulfur (sulfate) during an electron-microprobe study of several impact melt glass veins and pods in EET79001,LithC thin sections. As sulfur is very abundant in Martian soil, these S excesses were attributed to the mixing of a soil component containing aqueously altered secondary minerals with the LithC precursor materials prior to impact melt generation. Recently, we studied additional impact melt glasses in two basaltic shergottites, Zagami and Shergotty using procedures similar to those described. Significant S enrichments in Zagami and Shergotty impact melt glass veins similar to the EET79001, LithC glasses were found. In addition, we noticed the depletion of the mafic component accompanied by the enrichment of felsic component in these impact melt glass veins relative to the bulk host rock in the shergottites. To explain these observations, we present a model based on comminution of basaltic rocks due to meteoroid bombardment on martian regolith and mechanical fractionation leading to enrichment of felsics and depletion of mafics in the fine grained dust which is locally mobilized as a result of saltation and deflation due to the pervasive aeolian activity on Mars.

  3. Shergottite Impact Melt Glasses Contain Soil from Martian Uplands

    NASA Technical Reports Server (NTRS)

    Rao, M. N.; McKay, D. S.

    2002-01-01

    Martian meteorite (shergottite) impact melt glasses that contain high concentrations of martian atmospheric noble gases and show significant variations in Sr-87/Sr-86 isotopic ratios are likely to contain Martian surface fines mixed with coarser regolith materials. The mixed soil constituents were molten due to shock at the time of meteoroid impact near the Martian surface and the molten glass got incorporated into the voids and cracks in some shergottite meteorites. Earlier, Rao et al. found large enrichments of sulfur (sulfate) during an electron-microprobe study of several impact melt glass veins and pods in EET79001,LithC thin sections. As sulfur is very abundant in Martian soil, these S excesses were attributed to the mixing of a soil component containing aqueously altered secondary minerals with the LithC precursor materials prior to impact melt generation. Recently, we studied additional impact melt glasses in two basaltic shergottites, Zagami and Shergotty using procedures similar to those described by Rao et al. Significant S enrichments in Zagami and Shergotty impact melt glass veins similar to the EET79001, LithC glasses were found. In addition, we noticed the depletion of the mafic component accompanied by the enrichment of felsic component in these impact melt glass veins relative to the bulk host rock in the shergottites. To explain these observations, we present a model based on comminution of basaltic rocks due to meteroid bombardment on martian regolith and mechanical fractionation leading to enrichment of felsics and depletion of mafics in the fine grained dust which is locally mobilized as a result of saltation and deflation due to the pervasive aeolian activity on Mars.

  4. Martian meteorite Tissint records unique petrogenesis among the depleted shergottites

    NASA Astrophysics Data System (ADS)

    Basu Sarbadhikari, A.; Babu, E. V. S. S. K.; Vijaya Kumar, T.; Chennaoui Aoudjehane, H.

    2016-09-01

    Tissint, a new unaltered piece of Martian volcanic materials, is the most silica-poor and Mg-Fe-rich igneous rock among the "depleted" olivine-phyric shergottites. Fe-Mg zoning of olivine suggests equilibrium growth (<0.1 °C h-1) in the range of Fo80-56 and olivine overgrowth (Fo55-18) through a process of rapid disequilibrium (~1.0-5.0 °C h-1). The spatially extended (up to 600 μm) flat-top Fe-Mg profiles of olivine indicates that the early-stage cooling rate of Tissint was slower than the other shergottites. The chemically metastable outer rim of olivine (shergottites. Dominance of augite over plagioclase induced augite to control the Ca-buffer in the residual melt suppressing the plagioclase crystallization, which also caused a profound effect on the Al-content in the late-crystallized pyroxenes. Mineral chemical stability, phase-assemblage saturation, and pressure-temperature path of evolution indicates that the parent magma entered the solidus and left the liquidus field at a depth of 40-80 km in the upper mantle. Petrogenesis of Tissint appears to be similar to LAR 06319, an enriched olivine-phyric shergottite, during the early to intermediate stage of crystallization. A severe shock-induced deformation resulted in remelting (10-15 vol%), recrystallization (most Fe-rich phases), and exhumation of Tissint in a time scale of 1-8 yr. Tissint possesses some distinct characteristics, e.g., impact-induced melting and deformation, forming phosphorus-rich recrystallization rims of olivine, and shock-induced melt domains without relative enrichment of LREEs compared to the bulk; and shared characteristics, e.g., modal

  5. Martian meteorite Tissint records unique petrogenesis among the depleted shergottites

    NASA Astrophysics Data System (ADS)

    Basu Sarbadhikari, A.; Babu, E. V. S. S. K.; Vijaya Kumar, T.; Chennaoui Aoudjehane, H.

    2016-07-01

    Tissint, a new unaltered piece of Martian volcanic materials, is the most silica-poor and Mg-Fe-rich igneous rock among the "depleted" olivine-phyric shergottites. Fe-Mg zoning of olivine suggests equilibrium growth (<0.1 °C h-1) in the range of Fo80-56 and olivine overgrowth (Fo55-18) through a process of rapid disequilibrium (~1.0-5.0 °C h-1). The spatially extended (up to 600 μm) flat-top Fe-Mg profiles of olivine indicates that the early-stage cooling rate of Tissint was slower than the other shergottites. The chemically metastable outer rim of olivine (shergottites. Dominance of augite over plagioclase induced augite to control the Ca-buffer in the residual melt suppressing the plagioclase crystallization, which also caused a profound effect on the Al-content in the late-crystallized pyroxenes. Mineral chemical stability, phase-assemblage saturation, and pressure-temperature path of evolution indicates that the parent magma entered the solidus and left the liquidus field at a depth of 40-80 km in the upper mantle. Petrogenesis of Tissint appears to be similar to LAR 06319, an enriched olivine-phyric shergottite, during the early to intermediate stage of crystallization. A severe shock-induced deformation resulted in remelting (10-15 vol%), recrystallization (most Fe-rich phases), and exhumation of Tissint in a time scale of 1-8 yr. Tissint possesses some distinct characteristics, e.g., impact-induced melting and deformation, forming phosphorus-rich recrystallization rims of olivine, and shock-induced melt domains without relative enrichment of LREEs compared to the bulk; and shared characteristics, e.g., modal

  6. Formation of Secondary Lherzolite and Refertilization of the Subcontinental Lithospheric Mantle: The Record of Orogenic Peridotites

    NASA Astrophysics Data System (ADS)

    Garrido, Carlos J.; Varas-Reus, María Isabel; Bodinier, Jean-Louis; Marchesi, Claudio; Bosch, Delphine; Hidas, Károly

    2016-04-01

    Correlations observed between major and minor transition elements in tectonically-emplaced orogenic peridotites have classically been ascribed to variable degrees of melt extraction. There is a growing body of evidence indicating that these chemical variations mostly reflect melt redistribution and near solidus reactions superimposed onto previous melting depletion events. Here we will assess this hypothesis using a large database of peridotites from orogenic peridotites in the westernmost Mediterranean (Ronda and Beni Bousera peridotites). We show that lherzolite samples show some trends in major elements and modal variations that are inconsistent with their interpretation as depleted MORB mantle (DMM). These trends are more consistent with the secondary formation of lherzolites by refertilization processes involving a least two different near-solidus, melt-processes: refertilization by pyroxenite-derived melts and by hydrous melts leading, respectively, to secondary lherzolites with Ol/Opx and Cpx/Opx ratios greater than those expected from residues from a primitive upper mantle source. Together with their N-MORB, LREE-depleted pattern, their fertile lherzolitic composition may have been acquired as a result of melt-rock interaction processes associated with the thermomechanical erosion of lithospheric mantle by asthenosphere. Major refertilization of depleted subcontinental mantle is an alternative to the small degrees of melt extraction to account for LREE depletion in otherwise fertile orogenic lherzolites.

  7. On the chondrite-achondrite transition - Mineralogy and chemistry of Yamato 74160 (LL7)

    NASA Technical Reports Server (NTRS)

    Takeda, H.; Huston, T. J.; Lipschutz, M. E.

    1984-01-01

    Petrology, mineralogic properties and contents of major elements and trace elements Ag, Au, Bi, Cd, Co, Cs, Ga, In, Rb, Se, Te, Tl, U and Zn are reported (determined by radiochemical neutron activation analysis) in Yamato 74160, interpreted as an LL7 chondrite. All properties are consistent with this meteorite having been recrystallized and partially melted locally once at temperatures well above 1090 C under conditions such that some minerals (e.g. plagioclase, euhedral pyroxene, tetrataenite) grew from melt pockets and siderophilic and chalcophilic elements were lost by extraction into eutectic melt that drained away. Inhomogeneous plagioclase compositions and mobile element loss suggest shock as the most likely heat source. Yamato 74160, while inferentially chondritic, is a larval achondrite: even higher temperatures and longer times would have been required to cause the separations necessary to transform it to an identifiable achondrite type.

  8. Putative indigenous carbon-bearing alteration features in martian meteorite Yamato 000593.

    PubMed

    White, Lauren M; Gibson, Everett K; Thomas-Keprta, Kathie L; Clemett, Simon J; McKay, David S

    2014-02-01

    We report the first observation of indigenous carbonaceous matter in the martian meteorite Yamato 000593. The carbonaceous phases are heterogeneously distributed within secondary iddingsite alteration veins and present in a range of morphologies including areas composed of carbon-rich spheroidal assemblages encased in multiple layers of iddingsite. We also observed microtubular features emanating from iddingsite veins penetrating into the host olivine comparable in shape to those interpreted to have formed by bioerosion in terrestrial basalts. PMID:24552234

  9. PGE distribution in deformed lherzolites of the Udachnaya kimberlite pipe (Yakutia)

    NASA Astrophysics Data System (ADS)

    Ilyina, O. V.; Tychkov, N. S.; Agashev, A. M.; Golovin, A. V.; Izokh, A. E.; Kozmenko, O. A.; Pokhilenko, N. P.

    2016-04-01

    The results of the first study of the PGE distribution in deformed lherzolites of the Udachnaya kimberlite pipe (Yakutia) are presented here. The complex character of evolution of the PGE composition in the Deformed lherzolites is assumed to be the result of silicate metasomatism. At the first stage, growth in the amount of clinopyroxene and garnet in the rock is accompanied by a decrease in the concentration of the compatible PGE (Os, Ir). During the final stage, the rock is enriched with incompatible PGE (Pt, Pd) and Re possible due to precipitation of submicron-sized particles of sulfides in the interstitial space of these mantle rocks.

  10. The Martian Surface is old and so are Shergottites

    NASA Astrophysics Data System (ADS)

    Bouvier, A.; Blichert-Toft, J.; Vervoort, J. D.; Albarede, F.

    2005-12-01

    We report new Sm-Nd, Lu-Hf, and Pb-Pb mineral and whole-rock (WR) isotope data for the basaltic shergottite (BS) Zagami (Zag), as well as Pb-Pb WR isotope data for the BS Los Angeles (LA). The isotopic analyses were carried out by MC-ICP-MS at ENSL. The Sm-Nd and Lu-Hf data for Zag yield internal isochron ages of 155±9 Ma (MSWD=0.45) and 185±36 Ma (MSWD=1.2), respectively. While these young ages overlap with earlier Rb-Sr, Sm-Nd, and U-Pb ages (2), the Pb-Pb age does not. Our Pb isotope data on Zag and LA lie on the same Pb-Pb array as previous analyses of BS by (1), which, if interpreted as an isochron, indicate an age of ~4 Ga. The range of δ18O (3.9-5.2 permil) observed in shergottites (3, 4) is too broad to be accounted for by igneous processes only and attests to low-T interaction with fluids. The Martian surface appears to be covered with sulfates, while essentially lacking carbonates (5, 6), implying that the surface of Mars was once covered with acidic water bodies of unknown depths (7). An important observation is that apatite is a common phase in Zag and LA, as in all the shergottites (8), and explains why most of the REE, Th, U, and some fraction of Pb can be removed by leaching (9). The main inventory of Pb, however, resides in maskelynite. The Pb isotope data on shergottites, in conjunction with the existing body of geochemical and geophysical evidence, have important implications for the history of the Martian surface and lithosphere. A fundamental problem with the young crystallization ages for the Martian meteorites has been that these ages are difficult to reconcile with the large 182W and 142Nd isotopic anomalies present in these meteorites. On one hand, the anomalies from the extinct radionuclides appear to require a static, non-convecting mantle, whereas widespread volcanism on Mars as young as 150 Ma seems to require an actively convecting mantle. We suggest, based on the Pb isotope systematics of shergottites, that the Martian surface is

  11. Enriched Shergottite NWA 5298 As An Evolved Parent Melt: Trace Element Inventory

    NASA Technical Reports Server (NTRS)

    Hui, Hejiu; Peslier, Anne H.; Lapen, Thomas J.; Shafer, John; Brandon, Alan; Irving, Anthony

    2010-01-01

    Martian meteorite Northwest Africa 5298 is a basaltic shergottite that was found near Bir Gandouz (Morocco). Its martian origin was confirmed by oxygen isotopes [1], as well as Mn/Fe ratios in the pyroxenes and K/anorthite ratios in the plagioclases [2]. Here we present a petrographic and geochemical study of NWA 5298. Comparison of mineralogical and geochemical characteristics of this meteorite with other Martian rocks shows that NWA 5298 is not likely paired with any other known shergottites, but it has similarities to another basaltic shergottite Dhofar 378.

  12. Rare earth patterns in shergottite phosphates and residues

    NASA Technical Reports Server (NTRS)

    Laul, J. C.

    1987-01-01

    Leaching experiments with 1M HCl on ALHA 77005 powder show that rare earth elements (REE) are concentrated in accessory phosphate phases (whitlockite, apatite) that govern the REE patterns of bulk shergottites. The REE patterns of whitlockite are typically light REE-depleted with a negative Eu anomaly and show a hump at the heavy REE side, while the REE pattern of apatite (in Shergotty) is light REE-enriched. Parent magmas are calculated from the modal compositions of residues of ALHA 77005, Shergotty, and EETA 79001. The parent magmas lack a Eu anomaly, indicating that plagioclase was a late-stage crystallizing phase and that it probably crystallized before the phosphates. The parent magmas of ALHA 77005 and Shergotty have similar REE patterns, with a subchondritic Nd/Sm ratio. However, the Sm/Nd isotopoics require a light REE-depleted source for ALHA 77005 (if the crystallization age is less than 600 Myr) and a light REE-enriched source for Shergotty. Distant Nd and Sr isotopic signatures may suggest different source regions for shergottites.

  13. Petrogenesis of olivine-phyric shergottites Sayh al Uhaymir 005 and Elephant Moraine A79001 lithology A

    NASA Astrophysics Data System (ADS)

    Goodrich, Cyrena Anne

    2003-10-01

    Martian meteorites Sayh al Uhaymir (SaU) 005 and lithology A of EETA79001 (EET-A) belong to a newly emerging group of olivine-phyric shergottites. Previous models for the origin of such shergottites have focused on mixing between basaltic shergottite-like magmas and lherzolitic shergottite-like material. Results of this work, however, suggest that SaU 005 and EET-A formed from olivine-saturated magmas that may have been parental to basaltic shergottites. SaU 005 and EET-A have porphyritic textures of large (up to ˜3 mm) olivine crystals (˜25% in SaU 005; ˜13% in EET-A) in finer-grained groundmasses consisting principally of pigeonite (˜50% in SaU 005; ˜60% in EET-A), plagioclase (maskelynite) and < 7% augite. Low-Ti chromite occurs as inclusions in the more magnesian olivine, and with chromian ulvöspinel rims in the more ferroan olivine and the groundmass. Crystallization histories for both rocks were determined from petrographic features (textures, crystal shapes and size distributions, phase associations, and modal abundances), mineral compositions, and melt compositions reconstructed from magmatic inclusions in olivine and chromite. The following observations indicate that the chromite and most magnesian olivine (Fo 74-70 in SaU 005; Fo 81-77 in EET-A) and pyroxenes (low-Ca pyroxene [Wo 4-6] of mg 77-74 and augite of mg 78 in SaU 005; orthopyroxene [Wo 3-5] of mg 84-80 in EET-A) in these rocks are xenocrystic. (1) Olivine crystal size distribution (CSD) functions show excesses of the largest crystals (whose cores comprise the most magnesian compositions), indicating addition of phenocrysts or xenocrysts. (2) The most magnesian low-Ca pyroxenes show near-vertical trends of mg vs. Al 2O 3 and Cr 2O 3, which suggest reaction with a magma. (3) In SaU 005, there is a gap in augite composition between mg 78 and 73. (4) Chromite cores of composite spinel grains are riddled with cracks, indicating that they experienced some physical stress before being overgrown

  14. Highly Siderophile Elements in Terrestrial Planets: Evidence From Shergottite Meteorites

    NASA Astrophysics Data System (ADS)

    Brandon, A. D.; Puchtel, I. S.; Walker, R. J.

    2011-12-01

    Mechanisms for the emplacement of highly siderophile elements (HSE) in Earth's mantle have been debated for several decades. The chief conundrum is accounting for the high absolute and chondritic relative abundances of these elements in the terrestrial mantle, despite their strong tendency to partition into metal during core formation. Two end member models are most frequently discussed with respect to this issue. In the first model, abundances of HSE in planetary mantles are controlled by partitioning between segregating metal and silicate at high pressures, where some or all of the HSE may be considerably less siderophile, as may be appropriate for the base of a terrestrial magma ocean. A major weakness of this model is the generally chondritic HSE ratios in the mantle, which would require conditions under which the metal-silicate partitioning of all HSE would converge to approximately the same values. In the second model, termed late accretion, core extraction removes >99% of HSE from the Earth's mantle. The mantle is subsequently reseeded with HSE via continued accretion of 0.5 to 1% by mass of additional material. This model has been questioned because the timing of late accretion is poorly defined, and the mechanisms that can rapidly mix the late accreted materials to homogeneity within the mantle are difficult to envision. To examine this issue, 23 mafic to ultramafic shergottite meteorites from Mars, were measured for 187Re-187Os isotopes and HSE abundances. The objective is to gain insights on the early chemical evolution of the martian mantle to address the issue of HSE controls on the mantles of terrestrial bodies, with Mars serving as an important point of comparison to Earth. The shergottites display calculated initial 187Os/188Os ratios that correlate with the initial 143Nd/144Nd. Shergottites from mantle sources with long-term melt-depleted characteristics (initial ɛ143Nd of +36 to +40) have chondritic initial γ187Os ranging from -0.5 to +2

  15. Lead Isotope Compositions of Acid Residues from Olivine-Phyric Shergottite Tissint: Implications for Heterogeneous Shergottite Source Reservoirs

    NASA Technical Reports Server (NTRS)

    Moriwaki, R.; Usui, T.; Yokoyama, T.; Simon, J. I.; Jones, J. H.

    2015-01-01

    Geochemical studies of shergottites suggest that their parental magmas reflect mixtures between at least two distinct geochemical source reservoirs, producing correlations between radiogenic isotope compositions and trace element abundances. These correlations have been interpreted as indicating the presence of a reduced, incompatible element- depleted reservoir and an oxidized, incompatible- element-enriched reservoir. The former is clearly a depleted mantle source, but there is ongoing debate regarding the origin of the enriched reservoir. Two contrasting models have been proposed regarding the location and mixing process of the two geochemical source reservoirs: (1) assimilation of oxidized crust by mantle derived, reduced magmas, or (2) mixing of two distinct mantle reservoirs during melting. The former requires the ancient Martian crust to be the enriched source (crustal assimilation), whereas the latter requires isolation of a long-lived enriched mantle domain that probably originated from residual melts formed during solidification of a magma ocean (heterogeneous mantle model). This study conducts Pb isotope and trace element concentration analyses of sequential acid-leaching fractions (leachates and the final residues) from the geochemically depleted olivine-phyric shergottite Tissint. The results suggest that the Tissint magma is not isotopically uniform and sampled at least two geochemical source reservoirs, implying that either crustal assimilation or magma mixing would have played a role in the Tissint petrogenesis.

  16. Noble gases in twenty Yamato H-chondrites: Comparison with Allan Hills chondrites and modern falls

    NASA Technical Reports Server (NTRS)

    Loeken, TH.; Scherer, P.; Schultz, L.

    1993-01-01

    Concentration and isotopic composition of noble gases have been measured in 20 H-chrondrites found on the Yamato Mountains ice fields in Antarctica. The distribution of exposure ages as well as of radiogenic He-4 contents is similar to that of H-chrondrites collected at the Allan Hills site. Furthermore, a comparison of the noble gas record of Antarctic H-chrondrites and finds or falls from non-Antarctic areas gives no support to the suggestion that Antarctic H-chrondrites and modern falls derive from differing interplanetary meteorite populations.

  17. An "Andesitic" Component in Shergottites with Restored LREE Abundances?

    NASA Technical Reports Server (NTRS)

    Nyquist, L. E.; Shih, C.-Y.; Wiesmann, H.; Barrat, J. A.

    2002-01-01

    The shergottite Martian meteorites present a variety of oft-confusing petrologic features. In particular, represented among this subgroup are basalts with very depleted LREE abundances, as well as those with nearly chondritic overall REE abundances. The LREE-depleted basalts appear to more closely record the REE and isotopic features of their mantle source legions. Those basalts with more nearly chondritic REE abundances appear to contain an extra component often referred to as a "crustal" component. The addition of the crustal component tends to restore the overall REE abundance pattern towards chondritic relative abundances. Here we suggest that the crustal component could derive from andesitic rocks observed remotely to occur on the Martian surface, and which were analysed at the Pathfinder site.

  18. An "Andestic" Component in Shergottites with Restored LREE Abundances?

    NASA Technical Reports Server (NTRS)

    Nyquist, L. E.; Shih, C.-Y.; Wiesmann, H.; Barrat, J. A.

    2002-01-01

    The shergottite Martian meteorites present a variety of oft-confusing petrologic features. In particular, represented among this subgroup are basalts with very depleted LREE abundances, as well as those with nearly chondritic overall REE abundances. The LREE-depleted basalts appear to more closely record the REE and isotopic features of their mantle source regions. Those basalts with more nearly chondritic REE abundances appear to contain an extra component often referred to as a "crustal" component. The addition of the crustal component tends to restore the overall REE abundance pattern towards chondritic relative abundances. Here we suggest that the crustal component could derive from "andesitic" rocks observed remotely to occur on the Martian surface, and which were analysed at the Pathfinder site.

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

    NASA Technical Reports Server (NTRS)

    2004-01-01

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

  20. Solidus and liquidus temperatures and mineralogies for anhydrous garnet-lherzolite to 15 GPa

    NASA Technical Reports Server (NTRS)

    Herzberg, C. T.

    1983-01-01

    Strong convergence is noted, in experimental data for systems pertaining to anhydrous fertile garnet-lherzolite in the 6.5-15 GPa range, either to a common temperature or to temperatures differing by only about 100 C. The major element composition of magmas generated by even minor degrees of partial melting may be similar to the composition of the primordial, bulk silicate earth in an upper mantle stratigraphic column more than 160 km deep. Whether or not the solidus and liquidus intersect, the liquidus mineralogy for undepleted garnet-lherzolite compositions is found to change from olivine, at low pressures, to pyroxene, garnet, or a solid solution of both, at pressures greater than 10-15 GPa.

  1. Petrology and trace element geochemistry of Tissint, the newest shergottite fall

    NASA Astrophysics Data System (ADS)

    Balta, J. Brian; Sanborn, Matthew E.; Udry, Arya; Wadhwa, Meenakshi; McSween, Harry Y.

    2015-01-01

    AbstractThe fall and recovery of the Tissint meteorite in 2011 created a rare opportunity to examine a Martian sample with a known, short residence time on Earth. Tissint is an olivine-phyric <span class="hlt">shergottite</span> that accumulated olivine antecrysts within a single magmatic system. Coarse olivine grains with nearly homogeneous cores of Mg# >80 suggest slow re-equilibration. Many macroscopic features of this sample resemble those of LAR 06319, including the olivine crystal size distribution and the presence of evolved oxide and olivine compositions. Unlike LAR 06319, however, no magmatic hydrous phases were found in the analyzed samples of Tissint. Minor and trace element compositions indicate that the meteorite is the product of closed-system crystallization from a parent melt derived from a depleted source, with no obvious addition of a LREE-rich (crustal?) component prior to or during crystallization. The whole-rock REE pattern is similar to that of intermediate olivine-phyric <span class="hlt">shergottite</span> EETA 79001 lithology A, and could also be approximated by a more olivine-rich version of depleted basaltic <span class="hlt">shergottite</span> QUE 94201. Magmatic oxygen fugacities are at the low end of the <span class="hlt">shergottite</span> range, with log fO2 of QFM-3.5 to -4.0 estimated based on early-crystallized minerals and QFM-2.4 estimated based on the Eu in pyroxene oxybarometer. These values are similarly comparable to other depleted <span class="hlt">shergottites</span>, including SaU 005 and QUE 94201. Tissint occupies a previously unsampled niche in <span class="hlt">shergottite</span> chemistry: containing olivines with Mg# >80, resembling the enriched olivine-phyric <span class="hlt">shergottite</span> LAR 06319 in its crystallization path, and comparable to intermediate olivine-phyric <span class="hlt">shergottite</span> EETA 79001A, depleted olivine-phyric <span class="hlt">shergottite</span> DaG 476, and depleted basaltic <span class="hlt">shergottite</span> QUE 94201 in its trace element abundances and oxygen fugacity. The apparent absence of evidence for terrestrial alteration in Tissint</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.V53B4849U','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.V53B4849U"><span id="translatedtitle">Thermodynamic model for the calculation of multi pressure melting phase relation of anhydrous spinel <span class="hlt">lherzolite</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ueki, K.; Iwamori, H.</p> <p>2014-12-01</p> <p>Partial melting of mantle peridotite is an essential process for both material fractionation and cooling of the Earth. Melt generation process in the natural system is an open system process in terms of both energy and mass, and evolves with time. Thermodynamic modeling is a powerful approach to describe such phase relation, mass balance and energy balance during melting. This study presents a new thermodynamic model for the calculation of phase relations during the melting of anhydrous spinel <span class="hlt">lherzolite</span> at pressures between 1-2.5 GPa. The model is based on the total energy minimization algorithm for calculating phase equilibria within multicomponent systems and the thermodynamic configuration of Ueki and Iwamori [2013]. The model is based on a SiO2-Al2O3-FeO-Fe3O4-MgO-CaO system that includes silicate melt, olivine, clinopyroxene, orthopyroxene, and spinel as possible phases. The thermodynamic parameters for silicate melt end-member components are newly calibrated with a expanded-pressure calibration database. The temperatures and pressures used in this newly compiled calibration dataset are 1230-1600◦C and 0.9-3 GPa, corresponding to the stability range of spinel <span class="hlt">lherzolite</span>. The modeling undertaken during this study reproduces the general features of experimentally determined spinel <span class="hlt">lherzolite</span> melting phase relations at 1-2.5 GPa, including the solidus temperature, the melt composition, melting reaction, the degree of melting and the dF/dT curve. This new thermodynamic modeling also reproduces phase relations of various bulk compositions from relatively fertile to deplete spinel <span class="hlt">lherzolite</span> and can be used in the modeling of multi-pressure mantle melting within various natural settings.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016Litho.260...28S&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016Litho.260...28S&link_type=ABSTRACT"><span id="translatedtitle">Melt extraction and enrichment processes in the New Caledonia <span class="hlt">lherzolites</span>: Evidence from geochemical and Sr-Nd isotope data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Secchiari, Arianna; Montanini, Alessandra; Bosch, Delphine; Macera, Patrizia; Cluzel, Dominique</p> <p>2016-09-01</p> <p>The New Caledonia ophiolite (Peridotite Nappe) is dominated by mantle lithologies, composed of forearc-related refractory harzburgites and minor <span class="hlt">lherzolites</span> in both the spinel and plagioclase facies. In this study, a comprehensive geochemical data set (major, trace elements and Sr-Nd isotopes) is used to constrain the mantle evolution of the <span class="hlt">lherzolites</span> and their relationships with the basalts from the Poya Terrane, which tectonically underlies the mantle rocks. The majority of the <span class="hlt">lherzolites</span> are low-strain porphyroclastic tectonites. They likely record an asthenospheric origin followed by re-equilibration at lithospheric conditions, as supported by geothermometric estimates (T = 1100-940 °C and 920-890 °C for porphyroclastic and neoblastic spinel-facies assemblages, respectively). Olivine composition (Fo = 88.5-90.0 mol%), spinel Cr# ([molar 100 • Cr/(Cr + Al)] = 13-17) and relatively high amounts (7-8 vol%) of Al2O3- and Na2O-rich clinopyroxene (up to 0.5 and 6.5 wt.%, respectively) indicate a moderately depleted geochemical signature for the spinel <span class="hlt">lherzolites</span>. Bulk rock and clinopyroxene rare earth elements (REE) patterns display a typical abyssal-type signature, i.e. steeply plunging LREE accompanied by nearly flat HREE to MREE. Clinopyroxene REE compositions of the spinel <span class="hlt">lherzolites</span> may be reproduced by small amounts of fractional melting of a garnet <span class="hlt">lherzolite</span> precursor (~ 4%), followed by 4%-5% melting in the spinel peridotite field. The plagioclase <span class="hlt">lherzolites</span> show melt impregnation microstructures, Cr- and Ti-rich spinels and incompatible trace element enrichments (REE, Ti, Y, and Zr) in bulk rocks and clinopyroxenes. Impregnation modelling for these elements suggests that the plagioclase <span class="hlt">lherzolites</span> originated from residual spinel <span class="hlt">lherzolites</span> by entrapment of highly depleted (non-aggregated) MORB melt fractions in the shallow oceanic lithosphere. Nd isotope compositions of the investigated peridotites are consistent with derivation from an</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1983LPSC...14..229S&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1983LPSC...14..229S&link_type=ABSTRACT"><span id="translatedtitle">Mineral chemistry of the <span class="hlt">shergottites</span>, nakhlites, Chassigny, Brachina, pallasites and urelites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Smith, J. V.; Steele, I. M.; Leitch, C. A.</p> <p>1983-11-01</p> <p>The mineral chemistry is compared for selected achondrites. Olivine in the ALHA 77005 and EETA 79001 <span class="hlt">shergottites</span>, olivine-rich Chassigny and Brachina, and the nakhlites, contains Ni indicative of oxidizing conditions, whereas pallasitic and ureilitic olivines contain much lower Ni due to reducing conditions. The Brachina olivine and pyroxene have distinctively higher Fe/Mn than the <span class="hlt">shergottites</span> and Chassigny, further indicating that Brachina is unique. The Chassigny and 77005 olivines contain lower Cr2O3 (0.03 wt. pct) than the Brachina and 79001 olivines. Values of Fe/Mn for cumulus augites in nakhlites are higher than for the <span class="hlt">shergottites</span>, whereas those for ferropigeonites are not. The 77005 <span class="hlt">shergottite</span> contains troilite FeS in contrast to 79001, Shergotty, Zagami, and Chassigny, which contain pyrrhotite. Further analyses are needed, but the present survey indicates that at least Brachina is not chemically cogenetic with the other 'oxidized achondrites', and that the Fe/Mn ratio of the cumulus augites in nakhlites is a problem for the assignment of the nakhlites, <span class="hlt">shergottites</span>, and Chassigny to a single genetic group.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19840035683&hterms=PYRRHOTITE&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DPYRRHOTITE','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19840035683&hterms=PYRRHOTITE&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DPYRRHOTITE"><span id="translatedtitle">Mineral chemistry of the <span class="hlt">shergottites</span>, nakhlites, Chassigny, Brachina, pallasites and urelites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Smith, J. V.; Steele, I. M.; Leitch, C. A.</p> <p>1983-01-01</p> <p>The mineral chemistry is compared for selected achondrites. Olivine in the ALHA 77005 and EETA 79001 <span class="hlt">shergottites</span>, olivine-rich Chassigny and Brachina, and the nakhlites, contains Ni indicative of oxidizing conditions, whereas pallasitic and ureilitic olivines contain much lower Ni due to reducing conditions. The Brachina olivine and pyroxene have distinctively higher Fe/Mn than the <span class="hlt">shergottites</span> and Chassigny, further indicating that Brachina is unique. The Chassigny and 77005 olivines contain lower Cr2O3 (0.03 wt. pct) than the Brachina and 79001 olivines. Values of Fe/Mn for cumulus augites in nakhlites are higher than for the <span class="hlt">shergottites</span>, whereas those for ferropigeonites are not. The 77005 <span class="hlt">shergottite</span> contains troilite FeS in contrast to 79001, Shergotty, Zagami, and Chassigny, which contain pyrrhotite. Further analyses are needed, but the present survey indicates that at least Brachina is not chemically cogenetic with the other 'oxidized achondrites', and that the Fe/Mn ratio of the cumulus augites in nakhlites is a problem for the assignment of the nakhlites, <span class="hlt">shergottites</span>, and Chassigny to a single genetic group.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19910054777&hterms=Koeberl&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DKoeberl','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19910054777&hterms=Koeberl&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DKoeberl"><span id="translatedtitle">Preliminary examination of the <span class="hlt">Yamato</span>-86032 lunar meteorite. II - Major and trace element chemistry</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Koeberl, Christian; Warren, Paul H.; Lindstrom, Marilyn M.; Spettel, Bernhard; Fukuoka, Takaaki</p> <p>1989-01-01</p> <p>Results of the chemical composition analysis of <span class="hlt">Yamato</span>-86032, found in Antarctica in 1986, are summarized. The meteorite may be classified as an anorthositic breccia, but its trace element composition is different from the composition of the other known lunar meteorites. The major element chemistry of Y-86032 is similar to the other lunar meteorites, except for the iron content, which is lower by a factor of about 1.4. The abundances of incompatible and lithophile elements such as Zr, Hf, Ta, Th, or the REEs are very low and comparable to Y-82192/3. Other elements, in particular Fe, Ti, Sc, Cr, Mn, and Co, have lower abundances in Y-86032 than in Y-82192/3. Variations between individual analysis demonstrate that the rock itself is heterogeneous.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19940016420&hterms=Koeberl&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DKoeberl','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19940016420&hterms=Koeberl&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DKoeberl"><span id="translatedtitle">Consortium reports on lunar meteorites <span class="hlt">Yamato</span> 793169 and Asuka 881757, a new type of mare basalt</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Yanai, Keizo; Takeda, Hiroshi; Lindstrom, M. M.; Tatsumoto, M.; Torigoe, N.; Misawa, K.; Warren, P. H.; Kallemeyn, G. W.; Koeberl, C.; Kojima, H.</p> <p>1993-01-01</p> <p>Consortium studies on lunar meteorites <span class="hlt">Yamato</span> 793169 and Asuka 881757 (formerly Asuka-31) were performed to characterize these new samples from unknown locations in the lunar mare. Both meteorites are coarse-grained mare rocks having low Mg/Fe ratios (bulk mg'=30-35) and low TiO2 (1.5-2.5 percent in homogenized bulk samples). They are intermediate between VLT and low-Ti mare basalts. Although these meteorites are not identical to each other, their mineral and bulk compositions, isotopic systematics, and crystallization ages are remarkably similar and distinct from those of all other mare basalts. They appear to represent a new type of low-Ti mare basalt that crystallized at about 3.9Ga. These meteorites are inconsistent with the canonical correlation between the TiO2 contents and ages of mare basalts and suggest that our knowledge of lunar volcanism is far from complete.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993Metic..28..451T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993Metic..28..451T"><span id="translatedtitle">Xenoliths in the EETA 79001 <span class="hlt">Shergottite</span>: Geological and Astronomical Implications of Similarities to the ALHA 77005 and LEW 88516 <span class="hlt">Shergottites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Treiman, A. H.</p> <p>1993-07-01</p> <p>The EETA79001 <span class="hlt">shergottite</span> basalt contains xenoliths (to 1 cm diameter) that are comparable to the nonpoikilitic lithologies in the ALHA77005 and LEW88516 <span class="hlt">shergottites</span>. The xenoliths are fragments of an olivine-low-Ca-pyroxene rock, with lesser augite, chromite, and maskelynite; their textural patterns suggest an original heteradcumulate igneous rock [1,2] similar to ALHA77005 and LEW88516 [3,4]. Mineral phases in the xenoliths have experienced some chemical exchange with the host basalt [5]; however, their core compositions, especially pyroxenes, are nearly identical to those in LEW88516, and somewhat less restricted than those in ALHA77005 (new data; [1]; [2]; G. McKay, personal communication). Olivines in the xenoliths contain multiphase inclusions, ellipsoidal aggregates (to 200 micrometers diameter) of augite, alkali-rich, and Si-rich glasses, chromite, and a phosphate, in radiating or variolitic textures. These are interpreted as magmatic inclusions, remnants of original magma trapped in the olivines, and are petrographically identical to magmatic inclusions in the olivines of ALHA77005 and LEW88516 [4,6,7]. Shock effects in the xenoliths include zones of brown pleochroism in olivine, mosaickism of both olivine and pyroxene, formation of maskelynite from original plagioclase, recrystallization, and melting; these same effects are present but more severe in ALHA77005 and LEW88516 [8,9]. These many similarities among ALHA77005, LEW88516, and the EETA79001 xenoliths suggest that all were derived from similar, closely related igneous rocks (radioisotope ratios apparently preclude a comagmatic origin for ALHA77005 and the EETA79001 xenoliths [7,10,11]). If these three lithologies are closely related, they may be contemporaneous, and thus older than the EETA79001 basalt (host to the xenoliths). This inference may be consistent with radiometric crystallization ages: for ALHA77005 the age is 187 +- 12 (2 sigma) m.y. [11,5] or 154 +- 6 (2 sigma) m.y. [7]; for the EETA</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20040059931&hterms=rouge+planets&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Drouge%2Bplanets','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20040059931&hterms=rouge+planets&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Drouge%2Bplanets"><span id="translatedtitle">Compositional Controls on the Formation of Kaersutite Amphibole in <span class="hlt">Shergottite</span> Meteorites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Pitman, K. M.; Treiman, A. H.</p> <p>2004-01-01</p> <p>The <span class="hlt">shergottite</span> basalts, meteorites of Martian origin, contain rare small grains (approx. 10-100 microns diam.) of kaersutite, a Ca-amphibole rich in Al and Ti. Kaersutites have been used to estimate the water content of <span class="hlt">shergottites</span> and the Martian mantle; however, questions remain about the original water content of the amphiboles and if they formed from magma. We investigated the petrographic settings of amphiboles in two <span class="hlt">shergottites</span> and confirm that these amphiboles occur only in multiphase inclusions in pyroxene. In fact, kaersutite is found only in pigeonite. This suggests that the occurrence of amphibole is controlled in part by the composition of its host phase. Crystallization of host (cognate) pigeonite from a magmatic inclusion will enrich the remaining melt in Ca, Al, and Ti, supporting formation of kaersutite.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120011726','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120011726"><span id="translatedtitle">Complex Formation History of Highly Evolved Basaltic <span class="hlt">Shergottite</span>, Zagami</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Niihara, T.; Misawa, K.; Mikouchi, T.; Nyquist, L. E.; Park, J.; Hirata, D.</p> <p>2012-01-01</p> <p>Zagami, a basaltic <span class="hlt">shergottite</span>, contains several kinds of lithologies such as Normal Zagami consisting of Fine-grained (FG) and Coarse-grained (CG), Dark Mottled lithology (DML), and Olivine-rich late-stage melt pocket (DN). Treiman and Sutton concluded that Zagami (Normal Zagami) is a fractional crystallization product from a single magma. It has been suggested that there were two igneous stages (deep magma chamber and shallow magma chamber or surface lava flow) on the basis of chemical zoning features of pyroxenes which have homogeneous Mg-rich cores and FeO, CaO zoning at the rims. Nyquist et al. reported that FG has a different initial Sr isotopic ratio than CG and DML, and suggested the possibility of magma mixing on Mars. Here we report new results of petrology and mineralogy for DML and the Olivine-rich lithology (we do not use DN here), the most evolved lithology in this rock, to understand the relationship among lithologies and reveal Zagami s formation history</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19870038806&hterms=Beryllium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DBeryllium','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19870038806&hterms=Beryllium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DBeryllium"><span id="translatedtitle">Beryllium-10 contents of <span class="hlt">shergottites</span>, nakhlites, and Chassigny</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Pal, D. K.; Tuniz, C.; Moniot, R. K.; Savin, W.; Kruse, T.</p> <p>1986-01-01</p> <p>Accelerator mass spectrometry gives the following Be-10 contents (dpm/kg) for the SNC meteorites: Shergotty, 13.0 + or - 1.5 and 17.3 + or - 2.7; Zagami, 18.6 + or - 2.5 and 20.0 + or - 3.2; ALHA 77005, 15 + or - 3; EETA 79001A, 7.8 + or - 1.1 and 6.3 + or - 0.5; EETA 79001B, 8.5 + or - 1.1; Nakhla, 19.7 + or - 3.3; Lafayette, 18.1 + or - 2.5; Governador Valadares, 25.6 + or - 3.6; Chassigny, 20.5 + or - 3.1. The Be-10 contents of the NC meteorites indicate that significant accumulation of cosmogenic nuclides occurred in decimeter rather than planetary-size bodies. The agreement of the He-3, Ne-21, and Be-10 exposure ages of the <span class="hlt">shergottites</span> also supports small-body irradiation. A long terrestrial age for EETA 79001 appears unlikely.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19980018466','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980018466"><span id="translatedtitle">The <span class="hlt">Shergottite</span> Age Paradox and the Relative Probabilities of Ejecting Martian Meteorites of Differing Ages</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Borg, L. E.; Shih, C.-Y.; Nyquist, L. E.</p> <p>1998-01-01</p> <p>The apparent paradox that the majority of impacts yielding Martian meteorites appear to have taken place on only a few percent of the Martian surface can be resolved if all the <span class="hlt">shergottites</span> were ejected in a single event rather than in multiple events as expected from variations in their cosmic ray exposure and crystallization ages. If the <span class="hlt">shergottite</span>-ejection event is assigned to one of three craters in the vicinity of Olympus Mons that were previously identified as candidate source craters for the SNC (<span class="hlt">Shergottites</span>, Nakhlites, Chassigny) meteorites, and the nakhlite event to another candidate crater in the vicinity of Ceraunius Tholus, the implied ages of the surrounding terranes agree well with crater density ages. EN,en for high cratering rates (minimum ages), the likely origin of the <span class="hlt">shergottites</span> is in the Tharsis region, and the paradox of too many meteorites from too little terrane remains for multiple <span class="hlt">shergottite</span>-ejection events. However, for high cratering rates it is possible to consider sources for the nakhlltes which are away from the Tharsis region. The meteorite-yielding impacts may have been widely dispersed with sources of the young SNC meteorites in the northern plains, and the source of the ancient orthopyroxenite, ALH84001, in the ancient southern uplands. Oblique-impact craters can be identified with the sources of the nakhlites and the orthopyroxenite,, respectively, in the nominal cratering rate model, and with the <span class="hlt">shergottites</span> and orthopyroxenite, respectively, in the high cratering rate model. Thus, oblique impacts deserve renewed attention as an ejection mechanism for Martian meteorites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/19058996','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/19058996"><span id="translatedtitle">First finding of burkeite in melt inclusions in olivine from sheared <span class="hlt">lherzolite</span> xenoliths.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Korsakov, Andrey V; Golovin, Alexander V; De Gussem, Kris; Sharygin, Igor S; Vandenabeele, Peter</p> <p>2009-08-01</p> <p>For the first time burkeite was observed as a daughter phase in the melt inclusions in olivine by Raman spectroscopy. The olivine comes from sheared <span class="hlt">lherzolite</span> xenoliths from the Udachnaya-East kimberlite pipe (Yakutia, Russia). This anhydrous sulfate-carbonate mineral (Na(6)(CO(3))(SO(4))(2)) is generally considered to be a characteristic mineral in saline soils or in continental lacustrine evaporite deposits. Recently, however, this mineral was identified in hydrothermal fluids. Our observations indicate that burkeite can also be formed from a mantle-derived melt. PMID:19058996</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20130003564','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20130003564"><span id="translatedtitle">Water in Nominally Anhydrous Minerals from Nakhlites and <span class="hlt">Shergottites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Peslier, Anne H.</p> <p>2013-01-01</p> <p>Estimating the amount of water in the interior of terrestrial planets has tremendous implications on our understanding of solar nebula evolution, planet formation and geological history, and extraterrestrial volcanism. Mars has been a recent focus of such enquiry with complementary datasets from spacecrafts, rovers and martian meteorite studies. In planetary interiors, water can be dissolved in fluids or melts and hydrous phases, but can also be locked as protons attached to structural oxygen in lattice defects in nominally anhydrous minerals (NAM) such as olivine, pyroxene, or feldspar [1-3]. Measuring water in Martian meteorite NAM is challenging because the minerals are fragile and riddled with fractures from impact processes that makes them break apart during sample processing. Moreover, curing the sample in epoxy causes problems for the two main water analysis techniques, Fourier transform infrared spectrometry (FTIR) and secondary ionization mass spectrometry (SIMS). Measurements to date have resulted in a heated debate on how much water the mantle of Mars contains. SIMS studies of NAM [4], amphiboles [5], and apatites [6-8] from Martian meteorites report finding enough water in these phases to infer that the martian mantle is as hydrous as that of the Earth. On the other hand, a SIMS study of glass in olivine melt inclusions from <span class="hlt">shergottites</span> concludes that the Martian mantle is much drier [9]. The latter interpretation is also supported by the fact that most martian hydrous minerals generally have the relevant sites filled with Cl and F instead of H [10,11]. As for experimental results, martian basalt compositions can be reproduced using water as well as Cl in the parent melts [12,13]. Here FTIR is used to measure water in martian meteorite minerals in order to constrain the origin of the distribution of water in martian meteorite phases.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110007848','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110007848"><span id="translatedtitle">Rb-Sr And Sm-Nd Ages, and Petrogenesis of Depleted <span class="hlt">Shergottite</span> Northwest Africa 5990</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Shih, C. Y.; Nyquist, L. E.; Reese, Y.; Irving, A. J.</p> <p>2011-01-01</p> <p>Northwest Africa (NWA) 5990 is a very fresh Martian meteorite recently found on Hamada du Draa, Morocco and was classified as an olivine-bearing diabasic igneous rock related to depleted <span class="hlt">shergottites</span> [1]. The study of [1] also showed that NWA 5990 resembles QUE 94201 in chemical, textural and isotopic aspects, except QUE 94201 contains no olivine. The depleted <span class="hlt">shergottites</span> are characterized by REE patterns that are highly depleted in LREE, older Sm-Nd ages of 327-575 Ma and highly LREE-depleted sources with Nd= +35+48 [2-7]. Age-dating these samples by Sm-Nd and Rb-Sr methods is very challenging because they have been strongly shocked and contain very low abundances of light rare earth elements (Sm and Nd), Rb and Sr. In addition, terrestrial contaminants which are commonly present in desert meteorites will compromise the equilibrium of isotopic systems. Since NWA 5990 is a very fresh meteorite, it probably has not been subject to significant desert weathering and thus is a good sample for isotopic studies. In this report, we present Rb-Sr and Sm-Nd isotopic results for NWA 5990, discuss the correlation of the determined ages with those of other depleted <span class="hlt">shergottites</span>, especially QUE 94201, and discuss the petrogenesis of depleted <span class="hlt">shergottites</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20100003465','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20100003465"><span id="translatedtitle">Sulfur Isotopes in Gas-rich Impact-Melt Glasses in <span class="hlt">Shergottites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rao, M. N.; Hoppe, P.; Sutton, S. R.; Nyquist, Laurence E.; Huth, J.</p> <p>2010-01-01</p> <p>Large impact melt glasses in some <span class="hlt">shergottites</span> contain huge amounts of Martian atmospheric gases and they are known as gas-rich impact-melt (GRIM) glasses. By studying the neutron-induced isotopic deficits and excesses in Sm-149 and Sm-150 isotopes resulting from Sm-149 (n,gamma) 150Sm reaction and 80Kr excesses produced by Br-79 (n,gamma) Kr-80 reaction in the GRIM glasses using mass-spectrometric techniques, it was shown that these glasses in <span class="hlt">shergottites</span> EET79001 and Shergotty contain regolith materials irradiated by a thermal neutron fluence of approx.10(exp 15) n/sq cm near Martian surface. Also, it was shown that these glasses contain varying amounts of sulfates and sulfides based on the release patterns of SO2 (sulfate) and H2S (sulfide) using stepwise-heating mass-spectrometric techniques. Furthermore, EMPA and FE-SEM studies in basaltic-<span class="hlt">shergottite</span> GRIM glasses EET79001, LithB (,507& ,69), Shergotty (DBS I &II), Zagami (,992 & ,994) showed positive correlation between FeO and "SO3" (sulfide + sulfate), whereas those belonging to olivine-phyric <span class="hlt">shergottites</span> EET79001, LithA (,506, & ,77) showed positive correlation between CaO/Al2O3 and "SO3".</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20070000533','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20070000533"><span id="translatedtitle">Ar-Ar Age of NWA-1460 and Evidence For Young Formation Ages of the <span class="hlt">Shergottites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bogard, Donald D.; Park, Jisun</p> <p>2006-01-01</p> <p>Agreement of Ar-Ar, Sm-Nd, and Rb-Sr ages for NWA1460, and the inconsistency between a low shock-heating temperature for Zagami and the proposition that a 4.0 Gyr-old Zagami lost most of its Ar-40 are inconsistent with ancient formation ages for these <span class="hlt">shergottites</span>, but are consistent with relatively young igneous formation ages.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20100026405','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20100026405"><span id="translatedtitle">Argon Analyses of Lherzolic <span class="hlt">Shergottites</span> Y984028 and Y000097</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Park, J.; Nyquist, L. E.; Bogard, D. D.; Garrison, D. H.; Shih, C.-Y.; Mikouchi, T.; Misawa, K.</p> <p>2010-01-01</p> <p>Antarctic Martian meteorites <span class="hlt">Yamato</span> (Y) 984028 and Y000027/47/97 have similar textures, mineralogy, chemistry, and isotopic composition and are possibly paired. We analyzed the argon isotopic composition of Y984028 whole rock (WR) and pyroxene mineral separates (Px) in order to evaluate their trapped Ar components and compare with Y000097 Ar data. WR and Px yield an apparent Ar-39-Ar-40 age spectra of roughly 2 Ga, much older than the crystallization age determined by other isotopic techniques. Sm-Nd and Rb-Sr ages for Y984028 are approximately 170 Ma. This discrepancy is likely the byproduct of several coexisting Ar components, such as radiogenic 40Ar*, cosmogenic Ar, and trapped Ar from the multiple minerals, as well as multiple source origins. Similarly, the reported Ar-39-Ar-40 age of Y000097 is approximately 260 Ma with a Rb-Sr age of 147+/- 28 Ma and a Sm-Nd age of 152 +/- 13 Ma [4]. Apparently Ar-Ar ages of both Y984028 and Y000097 show trapped Ar components. Stepwise temperature extractions of Ar from Y984028 Px show several Arcomponents released at different temperatures. For example, intermediate temperature data (800-1100 C) are nominally consistent with the Sm-Nd and Rb-Sr radiometric ages (approximately 170 Ma) with an approximately Martian atmosphere trapped Ar composition with a Ar-40-Ar-36 ratio of approximately 1800. Based on K/Ca distribution, we know that Ar-39 at both lower and intermediate temperatures is primarily derived from plagioclase and olivine. Argon released during higher temperature extractions (1200-1500 C), however, differs significantly. The thermal profile of argon released from Martian meteorites is complicated by multiple sources, such as Martian atmosphere, Martian mantle, inherited Ar, terrestrial atmosphere, cosmogenic Ar. Obviously, Ar release at higher temperatures from Px should contain little terrestrial atmospheric component. Likewise, Xe-129/Xe-132 from high temperature extractions (1200-1800 C) gives a value above that</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015M%26PS..tmp..249H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015M%26PS..tmp..249H"><span id="translatedtitle">Petrography and geochemistry of the enriched basaltic <span class="hlt">shergottite</span> Northwest Africa 2975</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>He, Qi; Xiao, Long; Balta, J. Brian; Baziotis, Ioannis P.; Hsu, Weibiao; Guan, Yunbin</p> <p>2015-11-01</p> <p>We present a study of the petrology and geochemistry of basaltic <span class="hlt">shergottite</span> Northwest Africa 2975 (NWA 2975). NWA 2975 is a medium-grained basalt with subophitic to granular texture. Electron microprobe (EMP) analyses show two distinct pyroxene compositional trends and patchy compositional zoning patterns distinct from those observed in other meteorites such as Shergotty or QUE 94201. As no bulk sample was available to us for whole rock measurements, we characterized the fusion crust and its variability by secondary ion mass spectrometer (SIMS) measurements and laser ablation inductively coupled plasma spectroscopy (LA-ICP-MS) analyses as a best-available proxy for the bulk rock composition. The fusion crust major element composition is comparable to the bulk composition of other enriched basaltic <span class="hlt">shergottites</span>, placing NWA 2975 within that sample group. The CI-normalized REE (rare earth element) patterns are flat and also parallel to those of other enriched basaltic <span class="hlt">shergottites</span>. Merrillite is the major REE carrier and has a flat REE pattern with slight depletion of Eu, parallel to REE patterns of merrillites from other basaltic <span class="hlt">shergottites</span>. The oxidation state of NWA 2975 calculated from Fe-Ti oxide pairs is NNO-1.86, close to the QFM buffer. NWA 2975 represents a sample from the oxidized and enriched <span class="hlt">shergottite</span> group, and our measurements and constraints on its origin are consistent with the hypothesis of two distinct Martian mantle reservoirs: a reduced, LREE-depleted reservoir and an oxidized, LREE-enriched reservoir. Stishovite, possibly seifertite, and dense SiO2 glass were also identified in the meteorite, allowing us to infer that NWA 2975 experienced a realistic shock pressure of ~30 GPa.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70026675','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70026675"><span id="translatedtitle">Garnet <span class="hlt">lherzolites</span> from Louwrensia, Namibia: Bulk composition and P/T relations</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Boyd, F.R.; Pearson, D.G.; Hoal, Karin O.; Hoal, B.G.; Nixon, P.H.; Kingston, M.J.; Mertzman, S.A.</p> <p>2004-01-01</p> <p>Bulk, mineral and trace element analyses of garnet <span class="hlt">lherzolite</span> xenoliths from the Louwrensia kimberlite pipe, south-central Namibia, together with previously published Re-Os isotopic data [Chem. Geol. (2004)], form the most extensive set of chemical data for off-craton suites from southern Africa. The Louwrensia suite is similar to those from the Kaapvaal craton in that it includes both predominantly coarse-grained, equant-textured peridotites characterised by equilibration temperatures 1200 ??C. Redepletion ages range back to 2.1 Gy, concordant with the age of the crustal basement and about 1 Gy younger than the older peridotites of the adjacent Kaapvaal craton root. The coarse, low-temperature Louwrensia peridotites have an average Mg number for olivine of 91.6 in comparison to 92.6 for low-temperature peridotites from the craton. Orthopyroxene content averages 24 wt.% with a range of 11-40 wt.% for Louwrensia low-temperature peridotites, in comparison to a mean of 31.5 wt.% and a range of 11-44 wt.% for low-temperature peridotites from the Kaapvaal craton. Other major, minor and trace element concentrations in minerals forming Louwrensia <span class="hlt">lherzolites</span> are more similar to values in corresponding Kaapvaal peridotite minerals than to those in lithospheric peridotites of Phanerozoic age as represented by off-craton basalt-hosted xenoliths and orogenic peridotites. Proportions of clinopyroxene and garnet in both the Louwrensia and Kaapvaal <span class="hlt">lherzolites</span> overlap in the range up to 10 wt.% forming a trend extending towards pyrolite composition. Disequilibrium element partitioning between clinopyroxene and garnet for some incompatible trace elements is evidence that some of the trend is caused by enrichment following depletion. The disequilibrium is interpreted to have been caused by relatively recent growth of diopside, as previously suggested for cratonic peridotites. Attempts to constrain the depth of melting required to produce the Louwrensia peridotites suggests</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li class="active"><span>5</span></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_5 --> <div id="page_6" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li class="active"><span>6</span></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="101"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20090022115','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20090022115"><span id="translatedtitle">Sm-Nd, Rb-Sr, and Mn-Cr Ages of <span class="hlt">Yamato</span> 74013</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nyquist, L. E.; Shih, C.- Y.; Reese, Y.D.</p> <p>2009-01-01</p> <p><span class="hlt">Yamato</span> 74013 is one of 29 paired diogenites having granoblastic textures. The Ar-39 - Ar-40 age of Y-74097 is approximately 1100 Ma. Rb-Sr and Sm-Nd analyses of Y-74013, -74037, -74097, and -74136 suggested that multiple young metamorphic events disturbed their isotopic systems. Masuda et al. reported that REE abundances were heterogeneous even within the same sample (Y-74010) for sample sizes less than approximately 2 g. Both they and Nyquist et al. reported data for some samples showing significant LREE enrichment. In addition to its granoblastic texture, Y-74013 is characterized by large, isolated clots of chromite up to 5 mm in diameter. Takeda et al. suggested that these diogenites originally represented a single or very small number of coarse orthopyroxene crystals that were recrystallized by shock processes. They further suggested that initial crystallization may have occurred very early within the deep crust of the HED parent body. Here we report the chronology of Y-74013 as recorded in chronometers based on long-lived Rb-87 and Sm-147, intermediate- lived Sm-146, and short-lived Mn-53.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110015619','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110015619"><span id="translatedtitle">The Formation of Wassonite: A New Titanium Monosulfide Mineral in the <span class="hlt">Yamato</span> 691 Enstatite Chondrite</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nakamura-Messenger, K.; Keller, L. P.; Messenger, S.; Rubin, A. E.; Choi, B.-G.; Petaev, M. I.; Clemett, S. J.; Zhang, S.; Rahman, Z.; Oikawa, K.</p> <p>2011-01-01</p> <p>Wassonite, ideally stoichiometric TiS, is a titanium monosulfide not previously observed in nature, that was discovered within the <span class="hlt">Yamato</span> 691 EH3 enstatite chondrite [1]. Because of the submicrometer size of the wassonite grains, it was not possible to determine conventional macroscopic properties. However, the chemical composition and crystal structure were well constrained by extensive quantitative energy dispersive x-ray analysis and electron diffraction using transmission electron microscopy (TEM). The crystal system for wassonite is rhombohedral (a = 3.42 plus or minus 0.07, c = 26.50 plus or minus 0.53 Angstroms) with space group: R(sup 3 raised bar) m (R9 type), cell volume: 268.4 plus or minus 0.53 Angstroms(sup 3), Z=9, density (calculated): 4.452 grams per cubic centimeter, empirical formula: (Ti(sub 0.93), Fe(sub 0.06), Cr(sub 0.01))S. In this study, we discuss possible formation mechanisms of wassonite and its associated minerals based on the petrology, mineralogy, crystallography, thermodynamic calculations, Al/Mg isotopic systematics and the O-isotopic composition of the wassonite-bearing BO chondrule.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5142786','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5142786"><span id="translatedtitle">Mineral-chemical comparisons of MAC88105 with <span class="hlt">Yamato</span> lunar meteorites</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Takeda, Hiroshi; Mori, Hiroshi; Saito, Jun ); Miyamoto, Masamichi )</p> <p>1991-11-01</p> <p>The new lunar meteorite MAC88105 has been studied by mineral-chemical techniques and was compared with the <span class="hlt">Yamato</span> lunar meteorites. Clast types and pyroxene compositions of MAC88105 indicate that evidence for a pairing with any known lunar meteorites is unlikely. Clast-laden vitric breccia and comminuted mineral fragments in glassy matrix are common components as in other lunar meteorites, but granulitic clasts are not as common as in other lunar meteorites. The large and common granulite-like meta-igneous clasts still preserve lath-shaped plagioclase crystals with fine-grained olivine and pyroxenes in the interstices. Pyroxenes with mg number = Mg {times} 100/(Mg + Fe) between 70-48 mol% are common, but more Mg-rich pyroxenes and plutonic pyroxenes from nonmare pristine crustal rocks are rare. One basaltic clast contains pyroxenes with zoning trends more MG-rich than the above mg range and than those of the VLT basalts common in lunar meteorites. MAC88105 preserves true glass in the matrix as observed by a transmission electron microscope (TEM). The preservation of glassy materials indicates that MAC 88105 had a metamorphic annealing history different from other lunar meteorites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.V31A2769W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.V31A2769W"><span id="translatedtitle">An experimental study of the kinetics of <span class="hlt">lherzolite</span> and basalt interaction: Effect of water</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, C.; Liang, Y.; Xu, W.</p> <p>2012-12-01</p> <p>Melt-rock reaction happens in the asthenospheric mantle when interstitial melt and its host mantle rock are out of chemical equilibrium. It occurs in almost all major active tectonic regimes within the upper mantle and is responsible or partially responsible for a range of petrologic and geochemical observations. Significant progresses have been made in understanding the kinetics of melt-peridotite interaction in anhydrous systems through laboratory peridotite reactive dissolution experiments. The present study focuses on the effect of water on melt-peridotite interaction, a topic that is especially relevant to magma transport in the mantle wedge. A series of hydrous basalt-<span class="hlt">lherzolite</span> interaction experiments were conducted at 1250-1385°C and 0.8-2 GPa (3 hrs) using Au-Pd lined Mo capsules. To minimize Fe-loss, we first pre-saturated the Au-Pd-Mo capsule with the reacting melt at T-P conditions identical to dissolution runs, although Fe-unsaturated Au-Pd-Mo capsules were also used in a set of preliminary experiments. Starting material for the reacting hydrous basalt is a hornblende-bearing garnet pyroxenite (~13% Hb). For comparison, an anhydrous basalt-<span class="hlt">lherzolite</span> dissolution experiment was also conducted at 1385°C and 2 GPa (6 hrs) using the same starting composition but a graphite-lined Mo capsule that cannot retain water in the experimental charge. In the hydrous experiments, the starting pyroxenite is completely molten and the spinel <span class="hlt">lherzolite</span> is partially molten. A layer (100-760 μm) of mostly orthopyroxene (opx) + melt is formed between the reacting melt and starting <span class="hlt">lherzolite</span> that has transformed into a clinopyroxene depleted harzburgite. The opx grains in the high-porosity orthopyroxenite layer are euhedral and significantly larger than olivine and opx in the harzburgite. Furthermore, these opx grains are chemically zoned, and have small olivine inclusions, suggesting the growth of opx is at the expense of olivine. The opx rims are lower in MgO and SiO2</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1999Litho..48..287M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1999Litho..48..287M"><span id="translatedtitle">Growth of subcontinental lithosphere: evidence from repeated dike injections in the Balmuccia <span class="hlt">lherzolite</span> massif, Italian Alps</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mukasa, Samuel B.; Shervais, John W.</p> <p>1999-09-01</p> <p>The Balmuccia alpine <span class="hlt">lherzolite</span> massif is a fragment of subcontinental lithospheric mantle emplaced into the lower crust 251 Ma ago during the final, extensional phase of the Hercynian orogeny. The Balmuccia massif consists largely of <span class="hlt">lherzolite</span>, with subordinate harzburgite and dunite, and an array of dike rocks formed in the mantle before crustal emplacement. Dike rocks include websterite and bronzitite of the Cr-diopside suite, spinel clinopyroxenite and spinel-poor websterite of the Al-augite suite, gabbro and gabbronorite of the late gabbro suite, and hornblendite of the hydrous vein suite. The dike rocks display consistent intrusive relationships with one another, such that Cr-diopside suite dikes are always older than dikes and veins of the Al-augite suite, followed by dikes of the late gabbro suite and veins of the hydrous vein suite. Phlogopite (phl) veinlets that formed during interaction with the adjacent crust are the youngest event. There are at least three generations of Cr-diopside suite dikes, as shown by crosscutting relations. Dikes of the Al-augite suite form a polybaric fractionation series from spinel clinopyroxenite to websterite and feldspathic websterite, which crystallized from aluminous alkaline magmas at relatively high pressures. The late gabbro suite of dikes intruded at lower pressures, where plagioclase saturation occurred before significant mafic phase fractionation. Hornblendite veins have distinct compositional and isotopic characteristics, which show that they are not related to either the Al-augite suite or to the late gabbro dike suite. Cr-diopside suite dikes have Nd and Sr isotopic compositions similar to those of the host <span class="hlt">lherzolite</span> and within the range of compositions defined by ocean-island basalts. The Al-augite dikes and the hornblendite veins have Sr and Nd isotopic compositions similar to those of Cr-diopside suite <span class="hlt">lherzolite</span> and websterite. The late gabbro dikes have Nd and Sr isotopic compositions similar to mid</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.V23A2804G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.V23A2804G"><span id="translatedtitle">Hydration of Archean lithosphere: A chemico-physical case study of the <span class="hlt">lherzolitic</span> upper mantle below the Kaapvaal Craton</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gauert, C. D.; Globig, J.; Sommer, H.</p> <p>2013-12-01</p> <p>Since its formation in the Archean the subcratonic upper mantle of the Kaapvaal in southern Africa has undergone several processes of modification. Detailed analysis of Kaapvaal xenoliths from kimberlites show clear differences in age, origin, mineralogy, fertility and degree and type of alteration illustrating a period of complex interaction between asthenospheric and lithospheric mantle domains. The evolution of the cratonic lithosphere through time involved several metasomatic events leading to chemical and thermal anomalies. Global and regional 3-D shear wave velocity models are imaging a low velocity zone for the lower Kaapvaal lithosphere. However, regardless the resolution and significance of the lithospheric low velocity zone its origin is a matter of debate and is discussed to be either of thermal or chemical nature. Petrological evidence points to a rather chemical origin caused by refertilization and/or hydration of lithospheric mantle by metasomatizing fluids. Here we present a chemico-physical study of the <span class="hlt">lherzolitic</span> lithosphere below South Africa using a recalculated bulk composition based on analyses of the rock forming minerals from <span class="hlt">lherzolites</span> from the Roberts Victor Mine. The thermo-chemical calculations were carried out for a water saturated <span class="hlt">lherzolite</span> representative of published compositions of garnet <span class="hlt">lherzolites</span> from the Kaapvaal Craton in order to estimate the distribution of hydrous phases and the combined influence on physical properties as density and P- and S- wave velocities. Our results confirm the existence of a zone with slightly lower S-wave velocities and are supporting the idea of chemically layered <span class="hlt">lherzolitic</span> mantle that has been repeatedly hydrated by slab released volatiles in a two sided subduction model.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/9933162','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/9933162"><span id="translatedtitle">16O excesses in olivine inclusions in <span class="hlt">Yamato</span>-86009 and Murchison chondrites and their relation to CAIs.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hiyagon, H; Hashimoto, A</p> <p>1999-02-01</p> <p>In situ ion microprobe analyses of oxygen isotopes in <span class="hlt">Yamato</span>-86009 and Murchison chondrites show that they contain abundant olivine-rich inclusions that have large oxygen-16 (16O) excesses, similar to those in spinel grains in calcium-aluminium-rich inclusions in Allende and other carbonaceous chondrites. The existence of 16O-enriched olivine-rich inclusions suggests that oxygen isotopic anomalies were more extensive in the early solar system than was previously thought and that their origin may be attributed to a nebular chemical process rather than to an unidentified 16O-rich carrier of presolar origin. PMID:9933162</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120017925','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120017925"><span id="translatedtitle">Rb-Sr Isotopic Systematics of Alkali-Rich Fragments in the <span class="hlt">Yamato</span>-74442 LL-Chondritic Breccia</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Yokoyama, T.; Misawa, K.; Okano, O.; Shih, C.-Y.; Nyquist, L. E.; Simo, J. I.; Tappa, M. J.; Yoneda, S.</p> <p>2012-01-01</p> <p>Alkali-rich igneous fragments were identified in the brecciated LL-chondrites, Kr henberg (LL5)], Bhola (LL3-6) and <span class="hlt">Yamato</span> (Y)-74442 (LL4), and show characteristic fractionation patterns of alkaline elements. The K-Rb-Cs-rich fragments in Kr henberg, Bhola, and Y-74442 are very similar in mineralogy and petrography (olivine + pyroxene + glass), suggesting that they could have come from related precursor materials. We have undertaken Rb-Sr isotopic studies on alkali-rich fragments in Y-74442 to precisely determine their crystallization ages and the isotopic signatures of their precursor material(s).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1992Metic..27Q.218E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1992Metic..27Q.218E"><span id="translatedtitle">Mn-Cr Systematics in Sphalerites and Niningerites From Qingzhen and <span class="hlt">Yamato</span>69001: Implications Regarding Their Formation Histories</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>El Goresy, A.; Wadhwa, M.; Zinner, E. K.; Nagel, H.-J.; Janicke, J.; Crozaz, G.</p> <p>1992-07-01</p> <p>Recent Cr isotopic measurements of sphalerites and alabandites in three EL3 chondrites MAC88136, MAC88180, and MAC88184 and of sphalerites in the EH4 chondrite Indarch (El Goresy et al., 1992) revealed ^53Cr excesses (^53Cr*), resulting from the in situ decay of ^53Mn (tau(sub)1/2=3.7 Ma), in most grains analysed. However, the initial ^53Mn/^55Mn ratios calculated for these grains were quite variable, and it was concluded that redistribution of ^53Cr* by diffusional processes was the most likely cause for these variations. In a continuation of the previous work (El Goresy et al., 1992), we report new mineral-chemical and Cr-isotopic data for two EH3 chondrites, Qingzhen and <span class="hlt">Yamato</span> 69001. The distribution of Fe, Mg, and Mn in niningerites and sphalerites occurring in individual sulfide assemblages was determined by electron microprobe analysis. Among the meteorites of the EH3 subgroup, Qingzhen and <span class="hlt">Yamato</span> 69001 are unique in that niningerites in both meteorites display normal as well as reversed zoning, indicating complex thermal histories (Ehlers and El Goresy, 1988; Lin et al., 1989; Lin, 1991; Nagel, 1991). Niningerites have different MnS contents (9.2-32.6 mol% MnS in Qingzhen vs. 4.2- 6.3 mol% MnS in <span class="hlt">Yamato</span> 69001), as do the sphalerites (4.0-9.2 mol% MnS in Qingzhen vs. 2.0-3.5 mol% in <span class="hlt">Yamato</span> 69001). Sphalerites in both meteorites are normally zoned, with 46.0-49.8 mol% FeS in sphalerites from Qingzhen, and 42.3-49.7 mol% FeS in sphalerites from <span class="hlt">Yamato</span> 69001. The spatial distributions of Fe and Mg in niningerites and of Fe and Mn in sphalerites indicate complex processes that may have occurred before accretion and/or during later metamorphic events in the parent body (El Goresy and Ehlers, 1989; Lin, 1991; Nagel, 1991). Ion microprobe measurements of 6 sphalerites and 3 niningerites in Qingzhen and of 3 sphalerites and 2 niningerites in <span class="hlt">Yamato</span> 69001 showed that ^55Mn/^52Cr ratios in these sulfide phases are significantly lower than in sphalerites and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20090020654','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20090020654"><span id="translatedtitle">Sulfur Speciation in the Martian Regolith Component in <span class="hlt">Shergottite</span> Glasses</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rao, M. N.; Nyquist, Laurence E.; Sutton, S.; Huth, J.</p> <p>2009-01-01</p> <p>We have shown that Gas-Rich Impact-Melt (GRIM) glasses in Shergotty, Zagami, and EET79001 (Lith A and Lith B) contain Martian regolith components that were molten during impact and quenched into glasses in voids of host rock materials based on neutron-capture isotopes, i.e., Sm-150 excesses and Sm-149 deficits in Sm, and Kr-80 excesses produced from Br [1, 2]. These GRIM glasses are rich in S-bearing secondary minerals [3.4]. Evidence for the occurrence of CaSO4 and S-rich aluminosilicates in these glasses is provided by CaO-SO3 and Al2O3-SO3 correlations, which are consistent with the finding of gypsum laths protruding from the molten glass in EET79001 (Lith A) [5]. However, in the case of GRIM glasses from EET79001 (Lith B), Shergotty and Zagami, we find a different set of secondary minerals that show a FeO-SO3 correlation (but no MgOSO3 correlation), instead of CaO-SO3 and Al2O3-SO3 correlations observed in Lith A. These results might indicate different fluidrock interactions near the <span class="hlt">shergottite</span> source region on Mars. The speciation of sulfur in these salt assemblages was earlier studied by us using XANES techniques [6], where we found that Lith B predominantly contains Fe-sulfide globules (with some sulfate). On the other hand, Lith A showed predominantly Casulfite/ sulfate with some FeS. Furthermore, we found Fe to be present as Fe2+ indicating little oxidation, if any, in these glasses. To examine the sulfide-sulfate association in these glasses, we studied their Fe/Ni ratios with a view to find diagnostic clues for the source fluid. The Fe-sulfide mineral (Fe(0.93)Ni(0.3)S) in EET79001, Lith A is pyrrhotite [7, 8]. It yields an Fe/Ni ratio of 31. In Shergotty, pyrrhotite occurs with a molar ratio of Fe:S of 0.94 and a Ni abundance of 0.12% yielding a Fe/Ni ratio of approx.500 [8]. In this study, we determined a NiO content of approx.0.1% and FeO/NiO ratio of approx.420 in S-rich globules in #507 (EET79001, Lith B) sample using FE-SEM. In the same sample</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19860063607&hterms=earth+formation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dearth%2Bformation','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19860063607&hterms=earth+formation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dearth%2Bformation"><span id="translatedtitle">Core formation in the earth and <span class="hlt">shergottite</span> parent body (SPB) - Chemical evidence from basalts</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Treiman, A. H.; Drake, M. J.; Janssens, M.-J.; Wolf, R.; Ebihara, M.</p> <p>1986-01-01</p> <p>Abundances of siderophile and chalcophile elements in the <span class="hlt">shergottite</span> parental body (SPB) have been compared with those of the earth. To this end, new INAA and RNAA analyses of non-Antarctic meteorites have been performed, and the composition of the <span class="hlt">shergottite</span> SPB mantle has been inferred from the compositions of the SNC meteorites. The composition of the earth's mantle has been inferred from the compositions of terrestrial basalt. Finally, the effects of volatile depletion, core formation, and mineral/melt fractionation on the abundances of siderophile and chalcophile elements in the SPB and the earth have been taken into consideration. Compared to the earth, the SPB mantle is richer in moderately siderophile elements and more depleted with respect to chalcophile elements. The observed relative abundances of siderophile and chalcophile elements in the SPB and the earth mantles indicate that the SPB underwent accretion and/or differentiation processes which differ from those in the earth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19940016396&hterms=elephant&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Delephant','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19940016396&hterms=elephant&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Delephant"><span id="translatedtitle">Weathering features and secondary minerals in Antarctic <span class="hlt">Shergottites</span> ALHA77005 and LEW88516</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wentworth, Susan J.; Gooding, James L.</p> <p>1993-01-01</p> <p>Previous work has shown that all three sub-groups of the <span class="hlt">shergottite</span>, nakhlite, and chassignite (SNC) clan of meteorites contain aqueous precipitates of probable pre-terrestrial origin. In the context of secondary minerals, the most thoroughly studied <span class="hlt">shergottite</span> has been Elephant Moraine, Antarctica A79001 (EETA79001). The recognition of LEW88516 as the latest SNC specimen, and its close similarity with ALHA77005, invite a comparative study of the latter two meteorites, and with EETA79001, from the perspective of aqueous alteration. The fusion crusts of the two meteorites are quite similar except that ALHA77005 is more vesicular (possibly indicating a higher indigenous volatile content). Secondary aluminosilicates (and salts on LEW88516) of definite Antarctic origin partially fill vesicles and fractures on both fusion crusts. Interior samples of the two meteorites are grossly similar in that traces of secondary minerals are present in both.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150002847','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150002847"><span id="translatedtitle">Correlations Between Surficial Sulfur and a REE Crustal Assimilation Signature in Martian <span class="hlt">Shergottites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Jones, J. H.; Franz, H. B.</p> <p>2015-01-01</p> <p>Compared to terrestrial basalts, the Martian <span class="hlt">shergottite</span> meteorites have an extraordinary range of Sr and Nd isotopic signatures. In addition, the S isotopic compositions of many <span class="hlt">shergottites</span> show evidence of interaction with the Martian surface/ atmosphere through mass-independent isotopic fractionations (MIF, positive, non-zero delta(exp 33)S) that must have originated in the Martian atmosphere, yet ultimately were incorporated into igneous sulfides (AVS - acid-volatile sulfur). These positive delta(exp 33)S signatures are thought to be governed by solar UV photochemical processes. And to the extent that S is bound to Mars and not lost to space from the upper atmosphere, a positive delta(exp 33)S reservoir must be mass balanced by a complementary negative reservoir.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/618157','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/618157"><span id="translatedtitle">Sulfide isotopic compositions in <span class="hlt">shergottites</span> and ALH84001, and possible implications for life on Mars</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Greenwood, J.P.; McSween, H.Y. Jr.; Riciputi, L.R.</p> <p>1997-10-01</p> <p>The <span class="hlt">shergottite</span> and ALH84001 meteorites hold keys for understanding geologic and possibly biologic processes on Mars. Recently, it has been proposed that carbonates in ALH84001, and the Fe-sulfides they contain, are products of extraterrestrial biogenic activity. Here we report ion microprobe analyses of sulfides in <span class="hlt">shergottites</span> and ALH84001. The sulfur isotope ratios of igneous pyrrhotites in <span class="hlt">shergottites</span> (mean {delta}{sup 34}S{sub CDT}: Shergotty = -0.4{per_thousand}, Zagami = +2.7{per_thousand}, EETA79001A = 1.9{per_thousand}, EETA79001B = -1.7{per_thousand}, LEW88516 = -1.9{per_thousand}, QUE94201 = +0.8{per_thousand}) are similar to those of terrestrial ocean-floor basalts, suggesting that the sulfur isotopic composition of the Martian mantle may be similar to that of the mantle of the Earth. The sulfur isotopic systematics of ALH84001 sulfides are distinct from the <span class="hlt">shergottites</span>. Measured sulfur isotope ratios of eight pyrite grains ({delta}{sup 34}S{sub CDT} = +2.0 to +7.3{per_thousand}) in crushed zones confirm previously reported analyses of isotopically heavy sulfides and are indistinguishable from an Fe-sulfide zone within a carbonate globule ({delta}{sup 34}S{sub CDT} = +6.0{per_thousand}). Analyses of synthesized, fine-grained mixtures of sulfide, carbonate, and magnetite indicate than the measured sulfur isotope ratio is independent of the presence of carbonate and magnetite in the sputtered volume, confirming the accuracy of the analysis of the fine-grained sulfide in the carbonate globule. Terrestrial biogenic sulfate reduction typically results in light isotopic enrichments. The similarity of {delta}{sup 34}S values of the sulfides in ALH84001 imply that the Fe-sulfide zones within ALH84001 carbonates are probably not the result of bacterial reduction of sulfate. 38 refs., 3 figs., 1 tab.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110012697','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110012697"><span id="translatedtitle">Stabile Chlorine Isotope Study of Martian <span class="hlt">Shergottites</span> and Nakhlites; Whole Rock and Acid Leachates and Residues</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nakamura, N.; Nyquist, L. E.; Reese, Y.; Shih, C-Y; Fujitani, T.; Okano, O.</p> <p>2011-01-01</p> <p>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 <span class="hlt">shergottites</span> and nakhlites; whole rocks, HNO3-leachates and residues, and discuss the chlorine isotope evolution of planetary Mars.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.V52B..05G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.V52B..05G"><span id="translatedtitle">The Behavior of Fe3+/∑Fe During Partial Melting of Spinel <span class="hlt">Lherzolite</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gaetani, G. A.</p> <p>2014-12-01</p> <p>The use of wet chemistry and X-ray absorption near edge structure (XANES) spectroscopy to determine the oxidation state of Fe in submarine glasses and olivine-hosted melt inclusions has provided important new insights into the global systematics of Fe3+/∑Fe in mid-ocean ridge basalts (MORB) [1, 2]. Because MORB are aggregates of near-fractional partial melts formed by decompression melting of variably depleted peridotite, it is difficult to judge the extent to which they directly reflect the oxidation state of the oceanic upper mantle. To provide a theoretical framework within which to interpret Fe3+/∑Fe in MORB, I have developed a model that describes the behavior of Fe3+/∑Fe during spinel <span class="hlt">lherzolite</span> partial melting in a system closed to oxygen. Modeling is carried out by calculating the Fe3+/∑Fe of olivine using the point defect model of [3], and determining Fe3+/∑Fe of the bulk peridotite from mineral-mineral partitioning. The inter-mineral Fe3+/Fe2+ exchange coefficients are derived from Mössbauer data on natural spinel peridotites, and are parameterized in terms of oxygen fugacity, temperature, and the Fe content of the olivine. The Fe3+/∑Fe of the melt is determined by combining mass-balance with an equation relating the Fe3+/∑Fe of the melt to the fugacity of oxygen [4]. Spinel <span class="hlt">lherzolite</span> partial melting is modeled after [5]. Modeling results indicate that oxygen fugacity does not follow the fayalite-magnetite-quartz (FMQ) buffer during partial melting. For isobaric partial melting, the system becomes reduced relative to FMQ with increasing extent of melting. This results from an increase in the FMQ buffer with increasing temperature, whereas oxygen fugacity in the peridotite remains nearly constant. Conversely, during polybaric partial melting the oxidation state of the residual peridotite increases relative to FMQ. The effective partition coefficient for Fe3+is larger than previously thought, so that a redox couple with S is not required to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20070021571','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20070021571"><span id="translatedtitle">Excess Ar-40 in the Zagami <span class="hlt">Shergottite</span>: Does It Reveal Crystallization History?</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bogard, Donald D.; Park, Jisun</p> <p>2007-01-01</p> <p>The Zagami basaltic <span class="hlt">shergottite</span> has fine- and coarse-grained (FG & CG) areas, which may reflect partial crystallization in a deep, slowly cooled magma chamber to form Mg-rich pyroxene cores, followed by entrainment of these crystals into a magma that rose and crystallized near the surface. Late-stage melt pockets formed mesostasis and feldspar (maskelynite) having a range of compositions, but low water abundance. Higher I(sub Sr) in the FG portion may result from the second stage having incorporated old crustal rocks that failed to reach isotopic equilibrium. Zagami, like other <span class="hlt">shergottites</span>, contains excess Ar-40(sub xs) beyond that expected from internal decay of K-40 during its Sm-Nd age of 177 Myr. We suggest that at least a portion of this Ar-40(sub xs) in Zagami and some other <span class="hlt">shergottites</span> was inherited from the magma, much as is the case of MORBs on Earth. We made Ar-39-Ar-40 age determinations on feldspar and pyroxene separates from both the FG and CG portions of Zagami. If Zagami experienced an evolving fractional crystallization history, including possible crustal contamination of the magma, that might be indicated in differing amounts of Ar-40(sub xs) between mineral phases and between FG and CG portions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20130004220','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20130004220"><span id="translatedtitle">Chemical Composition of Four <span class="hlt">Shergottites</span> from Northwest Africa (NWA 2800, NWA, 5214, NWA 5990, NWA 6342)</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Yang, S.; Humayun, M.; Jefferson, G.; Fields, D.; Righter, K.; Irving, A. J.</p> <p>2013-01-01</p> <p><span class="hlt">Shergottites</span> represent the majority of recovered Martian meteorites. As basic igneous rocks, they formed from magmas that were emplaced in the Martian crust [1]. Due to the low ambient pressure of the Martian atmosphere, subaerial lavas and shallow magma chambers are expected to outgas volatile metals (e.g., Cd, Te, Re, Bi) [2]. The planetary abundances of the volatile siderophile and chalcophile elements are important at establishing the depth of core formation for Mars, and must be known as a baseline for understanding volcanic outgassing on Mars, particularly the large enrichments of S and Cl observed in modern Martian soils [3]. There is little data on volatile siderophile and chalcophile elements from Martian meteorites, excluding a few well-analyzed samples [2]. Further, a large number of <span class="hlt">shergottites</span> being recovered from North West Africa are in need of chemical analysis. All of the <span class="hlt">shergottites</span> are in need of state-of-the art analysis for such ratios as Ge/Si and Ga/Al, which can now be accomplished by LA-ICP-MS [2].</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011M%26PS...46....1Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011M%26PS...46....1Z"><span id="translatedtitle">Bounce Rock - A <span class="hlt">shergottite</span>-like basalt encountered at Meridiani Planum, Mars</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zipfel, Jutta; Schräder, Christian; Jolliff, Bradley L.; Gellert, Ralf; Herkenhoff, Kenneth E.; Rieder, Rudolf; Anderson, Robert; Bell, James F., III; Brückner, Johannes; Crisp, Joy A.; Christensen, Philip R.; Clark, Benton C.; de Souza, Paulo A., Jr.; Dreibus, Gerlind; D'Uston, Claude; Economou, Thanasis; Gorevan, Steven P.; Hahn, Brian C.; Klingelhäfer, Göstar; McCoy, Timothy J.; McSween, Harry Y., Jr.; Ming, Douglas W.; Morris, Richard V.; Rodionov, Daniel S.; Squyres, Steven W.; Wńnke, Heinrich; Wright, Shawn P.; Wyatt, Michael B.; Yen, Albert S.</p> <p>2011-01-01</p> <p>Abstract- The Opportunity rover of the Mars Exploration Rover mission encountered an isolated rock fragment with textural, mineralogical, and chemical properties similar to basaltic <span class="hlt">shergottites</span>. This finding was confirmed by all rover instruments, and a comprehensive study of these results is reported here. Spectra from the miniature thermal emission spectrometer and the Panoramic Camera reveal a pyroxene-rich mineralogy, which is also evident in Mössbauer spectra and in normative mineralogy derived from bulk chemistry measured by the alpha particle X-ray spectrometer. The correspondence of Bounce Rock’s chemical composition with the composition of certain basaltic <span class="hlt">shergottites</span>, especially Elephant Moraine (EET) 79001 lithology B and Queen Alexandra Range (QUE) 94201, is very close, with only Cl, Fe, and Ti exhibiting deviations. Chemical analyses further demonstrate characteristics typical of Mars such as the Fe/Mn ratio and P concentrations. Possible shock features support the idea that Bounce Rock was ejected from an impact crater, most likely in the Meridiani Planum region. Bopolu crater, 19.3 km in diameter, located 75 km to the southwest could be the source crater. To date, no other rocks of this composition have been encountered by any of the rovers on Mars. The finding of Bounce Rock by the Opportunity rover provides further direct evidence for an origin of basaltic <span class="hlt">shergottite</span> meteorites from Mars.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70033801','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70033801"><span id="translatedtitle">Bounce Rock-A <span class="hlt">shergottite</span>-like basalt encountered at Meridiani Planum, Mars</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Zipfel, J.; Schroder, C.; Jolliff, B.L.; Gellert, Ralf; Herkenhoff, K. E.; Rieder, R.; Anderson, R.; Bell, J.F., III; Brückner, J.; Crisp, J.A.; Christensen, P.R.; Clark, B. C.; de Souza, P.A.; Dreibus, G.; D'uston, C.; Economou, T.; Gorevan, S.P.; Hahn, B.C.; Klingelhofer, G.; McCoy, T.J.; McSween, H.Y.; Ming, D. W.; Morris, R.V.; Rodionov, D.S.; Squyres, S. W.; Wanke, H.; Wright, S.P.; Wyatt, M.B.; Yen, A. S.</p> <p>2011-01-01</p> <p>The Opportunity rover of the Mars Exploration Rover mission encountered an isolated rock fragment with textural, mineralogical, and chemical properties similar to basaltic <span class="hlt">shergottites</span>. This finding was confirmed by all rover instruments, and a comprehensive study of these results is reported here. Spectra from the miniature thermal emission spectrometer and the Panoramic Camera reveal a pyroxene-rich mineralogy, which is also evident in M??ssbauer spectra and in normative mineralogy derived from bulk chemistry measured by the alpha particle X-ray spectrometer. The correspondence of Bounce Rock's chemical composition with the composition of certain basaltic <span class="hlt">shergottites</span>, especially Elephant Moraine (EET) 79001 lithology B and Queen Alexandra Range (QUE) 94201, is very close, with only Cl, Fe, and Ti exhibiting deviations. Chemical analyses further demonstrate characteristics typical of Mars such as the Fe/Mn ratio and P concentrations. Possible shock features support the idea that Bounce Rock was ejected from an impact crater, most likely in the Meridiani Planum region. Bopolu crater, 19.3km in diameter, located 75km to the southwest could be the source crater. To date, no other rocks of this composition have been encountered by any of the rovers on Mars. The finding of Bounce Rock by the Opportunity rover provides further direct evidence for an origin of basaltic <span class="hlt">shergottite</span> meteorites from Mars. ?? The Meteoritical Society, 2011.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li class="active"><span>6</span></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_6 --> <div id="page_7" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active"><span>7</span></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="121"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19990020865&hterms=Dunite&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DDunite','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19990020865&hterms=Dunite&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DDunite"><span id="translatedtitle">What Were the Major Factors That Controlled Mineralogical Similarities and Differences of Basaltic, <span class="hlt">Lherzolitic</span> and Clinopyroxentic Martian Meteorites Within Each Group</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mikouchi, T.; Miyamoto, M.; McKay, G. A.</p> <p>1998-01-01</p> <p>Twelve martian meteorites that have been re- covered so far are classified into five groups (basalt, <span class="hlt">lherzolite</span>, clinopyroxenite, dunite, and orthopyroxenite) mainly from petrology and chemistry. Among them, the dunite and orthopyroxenite groups consist of only one meteorite each (dunite: Chassigny, orthopyroxenite: ALH 84001). The basalt group is the largest group and consists of four meteorites (Shergotty, Zagani, EETA 79001, and QUE 94201). The <span class="hlt">lherzolitic</span> and clinopyroxenitic groups include three meteorites each (<span class="hlt">Lherzolite</span>: ALH 77005, LEW 88516, and Y793605, clinopyroxenite: Nakhla, Governador Valadares, and Lafayette). These meteorites within each group are generally similar to the others, but none of them is paired with the others. In this abstract, we discuss the major factors that controlled mineralogical similarities and differences of basaltic, <span class="hlt">lherzolitic</span>, and clinopyroxenitic meteorites within each group. This may help in understanding their petrogenesis and original locations on Mars in general.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70018247','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70018247"><span id="translatedtitle">A study of REE and Pb, Sr and Nd isotopes in garnet-<span class="hlt">lherzolite</span> xenoliths from Mingxi, Fujian Province</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Wankang, H.; Junwen, W.; Basu, A.R.; Tatsumoto, M.</p> <p>1993-01-01</p> <p>The REE and Pb, Sr, Nd isotopes in three xenoliths from limburgite and scoria-breccias, including spinel-<span class="hlt">lherzolite</span>, spinel-garnet-<span class="hlt">lherzolite</span> and phlogopite-gamet-<span class="hlt">lherzolite</span>, were analysed. The REE contents of the xenoliths are 1.3 to 3.3 times those of the chondrites with their REE patterns characterized by weak LREE depletion. The143Nd/144Nd values of whole rocks and minerals range from 0.51306 to 0.51345 with ??Nd=+ 8.2- +15.8,206Pb/204 Pb < 18.673, and207Pb/204Pb < 15.574. All this goes to show that the upper mantle in Mingxi at the depth of 67-82 km is a depleted mantle of MORB type, with87Sr/86 Sr ratios 0.70237-0.70390. In Nd-Sr diagram the data points of whole rocks are all out of the mantle array, implying that the xenoliths from Mingxi have more radiogenic Sr isotopes than those of the mantle array. ?? 1993 Institute of Geochemistry, Chinese Academy of Sciences.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015P%26SS..117...24M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015P%26SS..117...24M"><span id="translatedtitle">Lunar meteorite <span class="hlt">Yamato</span>-983885: Noble gases, nitrogen and cosmic ray exposure history</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mahajan, Ramakant R.</p> <p>2015-11-01</p> <p>Noble gases and nitrogen have been in lunar meteorite from antartcica: the polymict regolith breccias, <span class="hlt">Yamato</span>-983885 (hereafter Y-983885). Y-983885 has highest concentration of trapped noble gases (Ar, Kr, and Xe) among all the lunar meteorites and returned lunar samples. Noble gases and nitrogen abundances measured in two samples of the lunar meteorite Y-983885. The concentration of trapped noble gases in Y-983885 (A) are, 20Ne=3.69×10-3, 36Ar=12.6×10-4, 84kr=8.57×10-7 and 132Xe=1.63×10-7 ccSTP/g. The cosmic-ray exposure ages for Y-983885 are thus calculated to be T21 (A)=1592±232 Ma and T21 (B)=574±85 Ma for 2π geometry (using production rates as per Hohenberg et al., 1978 and bulk composition). The exposure ages of samples A and B differ, indicating that they have undergone different exposure scenarios on the lunar surface. The different irradiation ages (T21 (A)=1592±232 Ma and T21 (B)=574±85 Ma) indicates that the regolith material which constitutes the meteorite Y-983885 resided at different shielding depths on lunar surface before agglomeration into the final meteorite. Exposure ages calculated using end member compositon like norite, basalt, tractolite (1947 to 1365 and 711 to 455 for A and B respectively) indicates clearly that the two samples A and B has undergone different exposure on Moon. The 20Ne/22Ne ratio of 13.60±0.01 in temperature step 400 °C of Y-983885 (A) demonstrate a clear retention of solar wind signature in this meteorite. The presence of high contents of trapped solar wind gases indicates that Y-983885 consists of mature lunar regolith material. Variable amounts of solar gases as well as cosmogenic noble gases indicate that Y-983885 (A and B) is compacted from several fragments that were exposed at the surface and/or at various depths in the regolith, before becoming part of Y-983885.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011CoMP..162.1139P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011CoMP..162.1139P"><span id="translatedtitle">The evolution of spinel <span class="hlt">lherzolite</span> xenoliths and the nature of the mantle at Kilbourne Hole, New Mexico</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Perkins, Dexter; Anthony, Elizabeth Y.</p> <p>2011-12-01</p> <p>In peridotites, olivine, clinopyroxene, and orthopyroxene are complex solid solutions with wide stability fields. Depending mostly on bulk composition and pressure, these minerals may be accompanied by plagioclase (low pressure), spinel (moderate pressure), or garnet (high pressure), resulting in 4-phase and rarer 5-phase assemblages. Although a particular mineral assemblage is stable over a range of P-T, the compositions of the individual minerals vary with changing P-T conditions. Application of standard geothermobarometers to olivine-clinopyroxene-orthopyroxene-spinel peridotites is problematic. An alternative approach is to use a bulk rock composition to calculate equilibrium phase diagrams to determine the conditions under which a particular assemblage is stable. This requires consideration of the 7-component system SiO2-Al2O3-Cr2O3-FeO-MgO-CaO-Na2O, internally consistent thermodynamic data for end members, and reliable mixing models for all mineral solutions. Experimental studies in simpler systems, and solution models from the literature, permit derivation of multicomponent thermodynamic mixing models for the key minerals. The models, when applied to xenoliths from Kilbourne Hole, constrain P and T of equilibration and are less sensitive to mineral compositional variations, or uncertainty in activity models, than standard thermobarometry. Our modeling provides the first tightly constrained pressure estimates for Kilbourne Hole, placing the xenoliths in the spinel stability field at depths (30-45 km) that correspond to the uppermost mantle beneath the Rio Grande Rift. The fine-grained equigranular <span class="hlt">lherzolite</span>, porphyroclastic <span class="hlt">lherzolite</span>, and some harzburgite-dunite specimens equilibrated at average conditions of 11.5 Kbar-930°C, 12 Kbar-990°C, and 13 Kbar-1,080°C, respectively. The mantle beneath the Rio Grande Rift is layered; the fine-grained equigranular <span class="hlt">lherzolite</span> derives from relatively shallow depth (35 km average), and the porphyroclastic <span class="hlt">lherzolite</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JAESc..67..199N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JAESc..67..199N"><span id="translatedtitle">Seismic structure of the extended continental crust in the <span class="hlt">Yamato</span> Basin, Japan Sea, from ocean bottom seismometer survey</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nakahigashi, Kazuo; Shinohara, Masanao; Yamada, Tomoaki; Uehira, Kenji; Mochizuki, Kimihiro; Kanazawa, Toshihiko</p> <p>2013-05-01</p> <p>We present the result of a seismic experiment conducted using ocean bottom seismometers and an airgun in the <span class="hlt">Yamato</span> Basin, of the Japan Sea. The Japan Sea is one of the most well-studied back-arc basins in the western Pacific. The Japan Sea is believed to have been formed by back-arc opening. However, the timing and formation processes of the opening of individual basins in and around the Japan Sea are not clear. To reveal the crustal structure of the <span class="hlt">Yamato</span> Basin it is important to consider the formation process of the Japan Sea. Therefore, we conducted a seismic survey and estimated the P-wave seismic velocity structure beneath the 170-km profile using a 2-D ray-tracing method. A layer with a P-wave velocity of 3.4-4.0 km/s underlies the sedimentary sections, which is thought to consist of a sill-and-sediment complex. The upper crust below the profile varies greatly in thickness. The thickness of the upper crust is 3.5 km in the thinnest part and 7 km in the thickest part. The thickness of the lower crust is approximately 8 km and is relatively constant over the profile. The total thickness of the crust is approximately 15 km including the sedimentary layer. The distribution of P-wave velocities and the thickness indicate that the crust in the <span class="hlt">Yamato</span> Basin is neither a typical continental nor a typical oceanic crust. From the point of view of seismic velocity, the obtained structure is more similar to a continental crust than to an oceanic crust. The large lateral thickness variation in the upper crust and the uniform thickness of the lower crust suggest that the crust in the study area was formed by rifting/extension of continental crust during the opening of the Japan Sea. The margins of the continent or of island arcs can be divided into two types: volcanic rifted margins and non-volcanic rifted margins. Volcanic rifted margins are normally classified by the presence of a high-velocity body in the lower crust. At the volcanic rifted margin, the high</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1990Tectp.179..227S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1990Tectp.179..227S"><span id="translatedtitle">Microstructure and texture in <span class="hlt">lherzolites</span> of the Balmuccia massif and their significance regarding the thermomechanical history</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Skrotzki, W.; Wedel, A.; Weber, K.; Müller, W. F.</p> <p>1990-07-01</p> <p>The microstructure and crystallographic preferred orientation (here referred to as texture) in <span class="hlt">lherzolites</span> of the Balmuccia massif have been investigated in order to unravel the thermomechanical history of this massif. Two deformation events may be recognized in the microstructure. In olivine the first deformation led to a coarse-grained dynamic recrystallization. The second deformation produced the subgrain and dislocation structure and a fine-grained dynamically recrystallized rim around the matrix grains. The subgrain boundaries are (100) and occasionally (001) tilt boundaries with variable tilt axis. The free dislocations are mainly screw dislocations with an [001] Burgers vector. An analysis of the dislocations bound in subgrain boundaries and the free dislocations yields {0 kl}[100] and { hk0}[001] as main activated slip systems. The orthopyroxenes are not recrystaUized and show deformation-induced clinoenstatite lamellae. The texture of olivine is characterized by [010] perpendicular to the foliation and [100] parallel to the lineation. In the orthopyroxene [100] is normal to the foliation and [001] normal to the lineation. The results are comparable with those found in similar massifs except the texture in the orthopyroxene. Stress and temperature estimates based on the dislocation density, subgrain size, dynamically recrystaUized grain sizes and the ortho-clinoenstatite transformation yield ≈ 20 MPa and ≈ 1000°C for deformation event I and 300 MPa and 650°C for deformation event II. The first and second deformation events are interpreted as intrusion of mantle material into the lower crust and the tilting of the Ivrea zone, respectively. From the correlation of the texture and microstructure it is concluded that the texture in the olivine reflects the first deformation event. The texture of the relatively hard and therefore only weakly deformed orthopyroxene may be explained by external rotation in the ductile olivine matrix.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20040062072&hterms=Samarium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DSamarium','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20040062072&hterms=Samarium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DSamarium"><span id="translatedtitle">Sm-Nd Age and Initial Sr-87/Sr-86 for <span class="hlt">Yamato</span> 980318: An Old Cumulate Eucrite</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nyquist, L. E.; Takeda, H.; Shih, C.-Y.; Wiesmann, H.</p> <p>2004-01-01</p> <p>The complex pyroxene exsolution texture of the Moore County cumulate eucrite was interpreted by Miyamoto and Takeda as indicating initial cooling at 160 C/Ma followed by a sudden temperature rise and final cooling at 0.35 C/yr. They suggested initial cooling at a depth of approx. 8 km near the base of Vesta s crust, followed by impact excavation to its surface. Young Sm-Nd ages of approx. 4456, 4460, and 4410 Ma, respectively, for the Moore County, Moama, and Serra de Mag cumulate eucrites are puzzling because closure to Nd isotopic exchange would occur in only a few Ma at the above initial cooling rate. The exception to young ages among the cumulate eucrites is EET87520, with a 147Sm-147 - Nd-143 age of 4547-4598 Ma. We report here initial results of a combined mineralogical/chronological study of the <span class="hlt">Yamato</span> 980318 feldspar-cumulate eucrite.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110007857','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110007857"><span id="translatedtitle">Acid-Sulfate-Weathering Activity in <span class="hlt">Shergottite</span> Sites on Mars Recorded in Grim Glasses</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rao, M. N.; Nyquist, L. E.; Ross, K.; Sutton, S. R.; Schwandt, C. S.</p> <p>2011-01-01</p> <p>Based on mass spectrometric studies of sulfur species in Shergotty and EET79001, [1] and [2] showed that sulfates and sulfides occur in different proportions in <span class="hlt">shergottites</span>. Sulfur speciation studies in gas-rich impact-melt (GRIM) glasses in EET79001 by the XANES method [3] showed that S K-XANES spectra in GRIM glasses from Lith A indicate that S is associated with Ca and Al presumably as sulfides/sulfates whereas the XANES spectra of amorphous sulfide globules in GRIM glasses from Lith B indicate that S is associated with Fe as FeS. In these amorphous iron sulfide globules, [4] found no Ni using FE-SEM and suggested that the globules resulting from immiscible sulfide melt may not be related to the igneous iron sulfides having approximately 1-3% Ni. Furthermore, in the amorphous iron sulfides from 507 GRIM glass, [5] determined delta(sup 34)S values ranging from +3.5%o to -3.1%o using Nano-SIMS. These values plot between the delta(sup 34)S value of +5.25%o determined in the sulfate fraction in Shergotty [6] at one extreme and the value of -1.7%o obtained for igneous sulfides in EET79001 and Shergotty [7] at the other. These results suggest that the amorphous Fe-S globules likely originated by shock reduction of secondary iron sulfate phases occurring in the regolith precursor materials during impact [7]. Sulfates in the regolith materials near the basaltic <span class="hlt">shergottite</span> sites on Mars owe their origin to surficial acid-sulfate interactions. We examine the nature of these reactions by studying the composition of the end products in altered regolith materials. For the parent material composition, we use that of the host <span class="hlt">shergottite</span> material in which the impact glasses are situated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002M%26PS...37..487B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002M%26PS...37..487B"><span id="translatedtitle">Petrology and chemistry of the basaltic <span class="hlt">shergottite</span> North West Africa 480</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Barrat, J. A.; Gillet, Ph.; Sautter, V.; Jambon, A.; Javoy, M.; Göpel, C.; Lesourd, M.; Keller, F.; Petit, E.</p> <p>2002-04-01</p> <p>North West Africa (NWA) 480 is a new martian meteorite of 28 g found in the Moroccan Sahara in November 2000. It consists mainly of large gray pyroxene crystals (the largest grains are up to 5 mm in length) and plagioclase converted to maskelynite. Excluding the melt pocket areas, modal analyses indicate the following mineral proportions: 72 vol% pyroxenes extensively zoned, 25% maskelynite, 1% phosphates (merrillite and chlorapatite), 1% opaque oxides (ilmenite, ulvospinel and chromite) and sulfides, and 1% others such as silica and fayalite. The compositional trend of NWA 480 pyroxenes is similar to that of Queen Alexandra Range (QUE) 94201 but in NWA 480 the pyroxene cores are more Mg-rich (En77-En65). Maskelynites display a limited zoning (An42-50Ab54-48Or2-4). Our observations suggest that NWA 480 formed from a melt with a low nuclei density at a slow cooling rate. The texture was achieved via a single-stage cooling where pyroxenes grew continuously. A similar model was previously proposed for QUE 94201 by McSween et al. (1996). NWA 480 is an Al-poor ferroan basaltic rock and resembles Zagami or Shergotty for major elements and compatible trace element abundances. The bulk rock analysis for oxygen isotopes yields V17O = +0.42%o, a value in agreement at the high margin, with those measured on other <span class="hlt">shergottites</span> (Clayton and Mayeda, 1996; Romanek et al., 1998; Franchi et al., 1999). Its CI-normalized rare earth element pattern is similar to those of peridotitic <span class="hlt">shergottites</span> such as Allan Hills (ALH)A77005, suggesting that these <span class="hlt">shergottites</span> shared a similar parent liquid, or at least the same mantle source.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013GeCoA.121..546P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013GeCoA.121..546P"><span id="translatedtitle">Ar-Ar ages and trapped Ar components in Martian <span class="hlt">shergottites</span> RBT 04262 and LAR 06319</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Park, Jisun; Bogard, Donald D.; Nyquist, Laurence E.; Garrison, Daniel H.; Mikouchi, Takashi</p> <p>2013-11-01</p> <p>We made 39Ar-40Ar (Ar-Ar) analyses of whole rock (WR) and mineral samples of two Martian <span class="hlt">shergottites</span>, RBT 04262 (RBT) and LAR 06319 (LAR), in order to determine their Ar-Ar ages and the 40Ar/36Ar ratios of the trapped Martian Ar they contain. All samples released trapped (excess) 40Ar and 36Ar and suggested Ar-Ar ages older than their formation ages. Because trapped Ar components having different 40Ar/36Ar were released at different extraction temperatures, we utilized only a portion of the data to derive preferred Ar-Ar ages. We obtain Ar-Ar ages of 171 ± 8 Ma for RBT plagioclase and 163 ± 13 Ma for LAR whole rock. We identify two trapped Ar components. At low temperatures, particularly for plagioclase, Trapped-A with 40Ar/36Ar 285 ± 3 was released, and we believe this is most likely absorbed terrestrial air. At high extraction temperatures, particularly for pyroxene, Trapped-B with 40Ar/36Ar 1813 ± 127 was released. The poikilitic/non-poikilitic texture of RBT and the presence of large pyroxene oikocrysts allowed a clear definition of Trapped-B. This Ar component is Martian, and its isotopic similarity to the Martian atmospheric composition suggests that it may represent Martian atmospheric Ar incorporated into the <span class="hlt">shergottite</span> melt via crustal rocks. Trapped-B partitioned into pyroxene at a constant molar ratio of K/36ArTr = 33.2 ± 9.5 × 106 for RBT 04262, and 80 ± 21 × 106 for LAR 06319. Trapped-A mixed in different proportions with Trapped-B could give apparently intermediate trapped 40Ar/36Ar compositions commonly observed in <span class="hlt">shergottites</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080009608','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080009608"><span id="translatedtitle">Petrology and Mineral Chemistry of New Olivine-Phyric <span class="hlt">Shergottite</span> RBT04262</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Dalton, H. A.; Peslier, A. H.; Brandon, A. D.; Lee, C.-T. A.; Lapen, T. J.</p> <p>2008-01-01</p> <p>RBT04262 was found by the 2004-2005 ANSMET team at the Roberts Massif in Antarctica. It is paired with RBT04261 and is classified as an olivine-phyric <span class="hlt">shergottite</span>. RBT04261 is 4.0 x 3.5 x 2.5 cm and 78.8 g, and RBT04262 is 6.5 x 5.5 x 3.5 cm and 204.6 g. Both were partially covered by a fusion crust [1]. Chemical analysis and mapping of this meteorite was performed using the Cameca SX100 electron microprobe at NASA Johnson Space Center.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015E%26PSL.411..142E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015E%26PSL.411..142E"><span id="translatedtitle">Partitioning of light lithophile elements during basalt eruptions on Earth and application to Martian <span class="hlt">shergottites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Edmonds, Marie</p> <p>2015-02-01</p> <p>An enigmatic record of light lithophile element (LLE) zoning in pyroxenes in basaltic <span class="hlt">shergottite</span> meteorites, whereby LLE concentrations decrease dramatically from the cores to the rims, has been interpreted as being due to partitioning of LLE into a hydrous vapor during magma ascent to the surface on Mars. These trends are used as evidence that Martian basaltic melts are water-rich (McSween et al., 2001). Lithium and boron are light lithophile elements (LLE) that partition into volcanic minerals and into vapor from silicate melts, making them potential tracers of degassing processes during magma ascent to the surface of Earth and of other planets. While LLE degassing behavior is relatively well understood for silica-rich melts, where water and LLE concentrations are relatively high, very little data exists for LLE abundance, heterogeneity and degassing in basaltic melts. The lack of data hampers interpretation of the trends in the <span class="hlt">shergottite</span> meteorites. Through a geochemical study of LLE, volatile and trace elements in olivine-hosted melt inclusions from Kilauea Volcano, Hawaii, it can be demonstrated that lithium behaves similarly to the light to middle rare Earth elements during melting, magma mixing and fractionation. Considerable heterogeneity in lithium and boron is inherited from mantle-derived primary melts, which is dominant over the fractionation and degassing signal. Lithium and boron are only very weakly volatile in basaltic melt erupted from Kilauea Volcano, with vapor-melt partition coefficients <0.1. Degassing of LLE is further inhibited at high temperatures. Pyroxene and associated melt inclusion LLE concentrations from a range of volcanoes are used to quantify lithium pyroxene-melt partition coefficients, which correlate negatively with melt H2O content, ranging from 0.13 at low water contents to <0.08 at H2O contents >4 wt%. The observed terrestrial LLE partitioning behavior is extrapolated to Martian primitive melts through modeling. The zoning</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6322645','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6322645"><span id="translatedtitle">Magmatic/metasomatic amphibole in the mantle: evidence from the Balmuccia <span class="hlt">lherzolite</span> massif, Ivrea zone, western Italian Alps</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Shervais, J.W.</p> <p>1985-01-01</p> <p>Amphibole and mica are the most important alkali-rich phases stable under mantle P-T conditions, and constitute the primary source of the alkalis needed to form basaltic magmas. Yet, the origin and distribution of these phases in the upper mantle is poorly understood. The Balmuccia <span class="hlt">lherzolite</span> massif is a small slice of subcontinental mantle in the western Alps that intruded granulite facies lower crust 250 m.y. ago, and was exposed during the Alpine orogeny. Amphibole (HB) ranging in composition from Ti-pargasite to kaersutite in a minor but widespread accessory phase in the <span class="hlt">lherzolite</span>, in websterite and bronzite dikes of the Cr-Di suite, and in pyroxenite and gabbro dikes of the Al-Aug suite. Textural and compositional relations show that HB in the Cr-Di and Al-Aug suite dikes formed by crystallization of residual magma, or by reaction between this magma and earlier formed phases (primarily spinel). Hb also occurs in thin (1-2 cm) veins of hornblendite and pyroxene hornblendite, and in the HB-enriched wallrock adjacent to these veins. Similar Hb veins in the Lherz massif have been shown to form from an alkali and water-enriched residual magma derived by filter pressing of Al-Aug pyroxenites. This origin is not possible at Balmuccia because the Hb veins have higher Ti, Cr, K/Na and Mgnumbers than any accessory Hb in Al-Aug suite dikes. Fractionation trends in the veins are controlled by HB. This requires that the HB veins formed from a separate and distinct parent magma that metasomatically enriched the <span class="hlt">lherzolite</span> on a local scale. However, remelting of the widespread pyroxenite dikes may constitute a more important source of alkalis than the rare HB-rich veins.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016GeCoA.185...64G&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016GeCoA.185...64G&link_type=ABSTRACT"><span id="translatedtitle">The behavior of Fe3+/∑Fe during partial melting of spinel <span class="hlt">lherzolite</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gaetani, Glenn A.</p> <p>2016-07-01</p> <p>This study presents an internally consistent model for the behavior of Fe3+/∑Fe during partial melting of spinel <span class="hlt">lherzolite</span>. The Fe3+/∑Fe ratio for olivine is calculated on the basis of point defect thermodynamics, and the oxidation states of iron in the other solid phases are calculated using Fe3+/Fe2+ distribution between olivine and orthopyroxene, clinopyroxene, or spinel. Conservation of mass is used to relate the Fe3+/Fe2+ ratio of partial melt to the concentrations of Fe3+ and Fe2+ in the initial and residual solids as a function of pressure, temperature, and oxygen fugacity. Results from isobaric batch melting calculations demonstrate that the Fe3+/∑Fe ratio of the partial melt decreases with increasing melt fraction. Conversely, the Fe3+/∑Fe ratio of the partial melt increases with increasing melt fraction during decompression batch melting. The relative oxygen fugacity of the upper mantle depends on both the oxidation state of iron and mantle potential temperature. Results from incremental decompression melting calculations in which 1% melt is produced for each 100 MPa of decompression and then removed from the residual solid indicate that relative oxygen fugacity calculated from the oxidation state of iron in basaltic glass does not represent a unique value for the oceanic upper mantle but, rather, reflects conditions in the lower portion of the melting regime. A 100 °C change in mantle potential temperature produces a change in relative oxygen fugacity of ∼0.8 log units, similar to the global range inferred from mid-ocean ridge basalt glasses. It is necessary, therefore, to compare relative oxygen fugacity calculated from basaltic glass with proxies for potential temperature before drawing conclusions on heterogeneity of the oxidation state of iron in the oceanic upper mantle. Results from model calculations also suggest that the sub-arc mantle is intrinsically more oxidizing than the oceanic mantle because it is cooler. The global correlation</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1987JGG....39..431N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1987JGG....39..431N"><span id="translatedtitle">Magnetic properties and remanent magnetization of a mixture of Fe-Ni alloys simulated to the <span class="hlt">Yamato</span> 74646 (LL6) chondrite</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nagai, H.; Momose, K.-I.; Funaki, M.</p> <p></p> <p>Magnetic properties of mixtures of two alloys, 5 at pct Ni-Fe and 29 at pct Ni-Fe, containing varying (from 0.0 to 100 at pct) concentrations of the former, were investigated and compared to those of a Ni-Fe alloy mixture simulating the <span class="hlt">Yamato</span> 74646 (LL6) chondrite; this mixture was prepared in accordance with the analysis data of Nagahara (1979). The original thermoremanent magnetization of alloy mixtures was acquired by heating for 2 h at 850 C and cooling to room temperature in a geomagnetic field. Remanent magnetization (RM) was measured during cooling at 77 K. It was found that the RM of the alloys simulating the <span class="hlt">Yamato</span> chondrite was thermally stable. The intensity of RM obtained by cooling at 77 K in geomagnetic field increased by about 10 percent compared to the original one, whereas that acquired by cooling at 77 K in zero magnetic field decreased by about 25 percent.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1986GeCoA..50.1031H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1986GeCoA..50.1031H"><span id="translatedtitle">Thermoluminescence and the shock and reheating history of meteorites. III - The <span class="hlt">shergottites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hasan, F. A.; Haq, M.; Sears, D. W. G.</p> <p>1986-06-01</p> <p>Thermoluminescence (TL) measurements on Shergotty, ALHA 77005, Zagami, and EETA 79001 (lithology A) have been used to obtain further information on the shock history of these meteorites. The level of TL sensitivity in the <span class="hlt">shergottites</span> varied by a factor of 10, but was always low, probably reflecting the amount of crystalline material in the maskelynite. There are trends in the TL peak temperature, peak width, and TL sensitivity which are believed to be associated with different proportions of feldspar in high- and low-temperature forms. This interpretation is consistent with the observed changes induced in the TL properties by annealing <span class="hlt">shergottites</span> at 400-900 C. It is suggested that the observed trends were produced during postshock crystallization at a variety of cooling rates, the increasing order of cooling rate being EETA 79001, Zagami, ALHA 77005, and Shergotty, and that there is high-temperature feldspar present in all the samples. This implies a postshock temperature above 600 C, and a small (less than 10 m) size of the ejecta. Current theories are well able to explain how objects of this size could have been ejected from Mars.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150002923','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150002923"><span id="translatedtitle">Formation and Preservation of the Depleted and Enriched <span class="hlt">Shergottite</span> Isotopic Reservoirs in a Convecting Martian Mantle</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kiefer, Walter S.; Jones, John H.</p> <p>2015-01-01</p> <p>There is compelling isotopic and crater density evidence for geologically recent volcanism on Mars, in the last 100-200 million years and possibly in the last 50 million years. This volcanism is due to adiabatic decompression melting and thus requires some type of present-day convective upwelling in the martian mantle. On the other hand, martian meteorites preserve evidence for at least 3 distinct radiogenic isotopic reservoirs. Anomalies in short-lived isotopic systems (Sm-146, Nd-142, Hf-182, W-182) require that these reservoirs must have developed in the first 50 to 100 million years of Solar System history. The long-term preservation of chemically distinct reservoirs has sometimes been interpreted as evidence for the absence of mantle convection and convective mixing on Mars for most of martian history, a conclusion which is at odds with the evidence for young volcanism. This apparent paradox can be resolved by recognizing that a variety of processes, including both inefficient mantle mixing and geographic separation of isotopic reservoirs, may preserve isotopic heterogeneity on Mars in an actively convecting mantle. Here, we focus on the formation and preservation of the depleted and enriched isotopic and trace element reservoirs in the <span class="hlt">shergottites</span>. In particular, we explore the possible roles of processes such as chemical diffusion and metasomatism in dikes and magma chambers for creating the isotopically enriched <span class="hlt">shergottites</span>. We also consider processes that may preserve the enriched reservoir against convective mixing for most of martian history.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19860063603&hterms=effect+nuclear&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Deffect%2Bnuclear','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19860063603&hterms=effect+nuclear&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Deffect%2Bnuclear"><span id="translatedtitle">Nuclear tracks, Sm isotopes and neutron capture effects in the Elephant Morraine <span class="hlt">shergottite</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rajan, R. S.; Lugmair, G.; Tamhane, A. S.; Poupeau, G.</p> <p>1986-01-01</p> <p>Nuclear track studies, uranium concentration measurements and Sm-isotope studies have been performed on both lithologies A and B of the Elephant Morraine <span class="hlt">shergottite</span>, EETA 79001. Track studies show that EETA 79001 was a rather small object in space with a preatmospheric radius of 12 + or - 2 cm, corresponding to a preatmospheric mass of 28 + or - 13 kg. Phosphates have U concentrations ranging from 0.3 to 1.3 ppm. There are occasional phosphates with excess fission tracks, possibly produced from neutron-induced fission of U and Th, during the regolith exposure in the <span class="hlt">shergottite</span> parent body (SPB). Sm-isotope studies, while not showing any clear-cut excess in Sm-150, make it possible to derive meaningful upper limits to thermal neutron fluences of 2 to 3 x 10 to the 15th n/sq cm, during a possible regolith irradiation. These limits are consistent with the track data and also make it possible to derive an upper limit to the neutron exposure age of EETA 79001 of 55 Myr in the SPB regolith.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19870046806&hterms=earth+chemical+composition&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dearth%2Bchemical%2Bcomposition','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19870046806&hterms=earth+chemical+composition&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dearth%2Bchemical%2Bcomposition"><span id="translatedtitle">Core formation in the <span class="hlt">shergottite</span> parent body and comparison with the earth</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Treiman, Allan H.; Jones, John H.; Drake, Michael J.</p> <p>1987-01-01</p> <p>Abundances of elements in <span class="hlt">shergottite</span>, nakhlite, and Chassigny meteorites which originated on a single planet, the <span class="hlt">shergottite</span> parent body (SPB), were examined with the aim of elucidating the chemical conditions of metal separation and core formation in the SPB and of testing present models of planetary core formation. Using partition coefficients and the SPB mantle composition determined in earlier studies, the abundances of Ag, Au, Co, Ga, Mo, Ni, P, Re, S, and W were modeled, with free parameters being oxygen fugacity, proportion of solid metal formed, proportion of metallic liquid formed, and proportion of silicate that is molten. It is shown that the abundances of all elements (except Mo) could be reproduced using models with these four free parameters. In contrast to the SPB, an equivalent model used to predict element abundances in the earth's mantle was shown by Jones and Drake (1986) to be inadequate; there is at present no hypothesis capable of quantitatively reproducing the elemental abundances of the earth's mantle. The contrast suggests that these two terrestrial planets (assuming that the SPB is Mars) may have accreted or differentiated differently.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1986GeCoA..50.1039R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1986GeCoA..50.1039R"><span id="translatedtitle">Nuclear tracks, SM isotopes and neutron capture effects in the Elephant Morraine <span class="hlt">shergottite</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rajan, R. S.; Lugmair, G.; Tamhane, A. S.; Poupeau, G.</p> <p>1986-06-01</p> <p>Nuclear track studies, uranium concentration measurements and Sm-isotope studies have been performed on both lithologies A and B of the Elephant Morraine <span class="hlt">shergottite</span>, EETA 79001. Track studies show that EETA 79001 was a rather small object in space with a preatmospheric radius of 12 + or - 2 cm, corresponding to a preatmospheric mass of 28 + or - 13 kg. Phosphates have U concentrations ranging from 0.3 to 1.3 ppm. There are occasional phosphates with excess fission tracks, possibly produced from neutron-induced fission of U and Th, during the regolith exposure in the <span class="hlt">shergottite</span> parent body (SPB). Sm-isotope studies, while not showing any clear-cut excess in Sm-150, make it possible to derive meaningful upper limits to thermal neutron fluences of 2 to 3 x 10 to the 15th n/sq cm, during a possible regolith irradiation. These limits are consistent with the track data and also make it possible to derive an upper limit to the neutron exposure age of EETA 79001 of 55 Myr in the SPB regolith.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active"><span>7</span></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_7 --> <div id="page_8" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="141"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19860063602&hterms=thermoluminescence&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dthermoluminescence','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19860063602&hterms=thermoluminescence&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dthermoluminescence"><span id="translatedtitle">Thermoluminescence and the shock and reheating history of meteorites. III - The <span class="hlt">shergottites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hasan, F. A.; Haq, M.; Sears, D. W. G.</p> <p>1986-01-01</p> <p>Thermoluminescence (TL) measurements on Shergotty, ALHA 77005, Zagami, and EETA 79001 (lithology A) have been used to obtain further information on the shock history of these meteorites. The level of TL sensitivity in the <span class="hlt">shergottites</span> varied by a factor of 10, but was always low, probably reflecting the amount of crystalline material in the maskelynite. There are trends in the TL peak temperature, peak width, and TL sensitivity which are believed to be associated with different proportions of feldspar in high- and low-temperature forms. This interpretation is consistent with the observed changes induced in the TL properties by annealing <span class="hlt">shergottites</span> at 400-900 C. It is suggested that the observed trends were produced during postshock crystallization at a variety of cooling rates, the increasing order of cooling rate being EETA 79001, Zagami, ALHA 77005, and Shergotty, and that there is high-temperature feldspar present in all the samples. This implies a postshock temperature above 600 C, and a small (less than 10 m) size of the ejecta. Current theories are well able to explain how objects of this size could have been ejected from Mars.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19860034312&hterms=Dunite&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DDunite','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19860034312&hterms=Dunite&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DDunite"><span id="translatedtitle">SNC meteorites - Clues to Martian petrologic evolution?. [<span class="hlt">Shergottites</span>, Nakhlites and Chassigny</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mcsween, H. Y., Jr.</p> <p>1985-01-01</p> <p><span class="hlt">Shergottites</span>, nakhlites and the Chassigny meteorites (SNC group) may have originated on Mars. The <span class="hlt">shergottites</span> are medium-grained basalts, the nakhlites are pyroxenites and the Chassigny is a dunite. The SNC group is petrologically diverse but differs from all other known achondrites in terms of mineral chemistry, the redox state, the oxygen isotopic composition and the radiometric ages. The SNC stones are mafic and ultramafic cumulate rocks with mineralogies that indicate rapid cooling and crystallization from tholeiitic magmas which contained water and experienced a high degree of oxidation. The characteristics suggest formation from a large parent body, i.e., a planet, but not earth. The estimated ages for the rocks match the estimated ages for several mapped Martian volcanoes in the Tharsis region. Additionally, the elemental and isotopic abundances of atmospheric gases embedded in melts in the SNC stones match Viking Lander data for the Martian atmosphere. However, reasons are cited for discounting the possibility that a large meteorite(s) collided with Mars about 180 myr ago and served as the mechanism for ejecting the SNC stones to earth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/803430','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/803430"><span id="translatedtitle">Exposure History of <span class="hlt">Shergottites</span> Dar Al Gani 476/489/670/735 and Sayh Al Uhaymir 005</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Nishiizumi, N.; Caffee, M.; Jull, A.J.T.; Klandrud, S.E.</p> <p>2001-04-01</p> <p>Four basaltic <span class="hlt">shergottites</span>, Dar al Gani (DaG) 476, 489, 670, and 735 were found in the Libyan Sahara [1-3]; two basaltic <span class="hlt">shergottites</span>, Sayh al Uhaymir (SaU) 005 and 008 were found in Oman [4]. Recently SaU 051 was also recognized as a possible pair of SaU 005/008. Although the collection sites were different, the texture, bulk chemical compositions, and noble gas compositions of these <span class="hlt">shergottites</span> are similar [e.g. 4]. However, cosmic-ray-produced noble gases alone cannot unambiguously constrain the irradiation history for these objects. From a combination of cosmogenic stable- and radionuclides, exposure histories, and ejection conditions from the hypothesized Martian parent body, and genetic relationships between the Martian meteorites can be determined. In addition to those nuclides produced by galactic cosmic rays (GCR) are those produced by solar cosmic rays (SCR). Radionuclides produced by SCRs reside in the uppermost few centimeters of extraterrestrial bodies and their presence in meteorites indicates the degree to which a meteorite has been ablated. Previous work shows ablation is less than 1-2 cm in at least three <span class="hlt">shergottites</span>, ALH 77005, Shergotty, and EETA79001 [e.g. 5] and so it is possible some SCR signal may be observed in these meteorites. This suggests that the atmospheric entry velocity and/or entry angle of these <span class="hlt">shergottites</span> is much lower than the velocity and/or entry angle of most ordinary chondrites. We report here preliminary results of cosmogenic nuclides, {sup 14}C (half-life = 5,730 yr), {sup 36}Cl (3.01 x 10{sup 5} yr), {sup 26}Al (7.05 x 10{sup 5} yr), and {sup 10}Be(1.5 x 10{sup 6} yr).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..1613367G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..1613367G"><span id="translatedtitle">Petrology of pyroxenitic vein in spinel-plagioclas <span class="hlt">lherzolites</span> from Zabargad island, Red Sea, Egypt</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gjerazi, Ingrid; Ntaflos, Theodoros</p> <p>2014-05-01</p> <p>) supporting the lithospheric mantle origin of the Zabargad peridotites. The presence of amphibole appears to be the result of a reaction between metasomatic introduced fluids and matrix clinopyroxene. The plagioclase is Ca-rich (An63--73) and always is surrounding spinel. A metasomatic origin of the plagioclase seems to be unlike because augites have plagioclase exsolution lamellae with similar composition to the spinel surrounding plagioclase. This is an evidence for incipient transformation of spinel- to plagioclase-<span class="hlt">lherzolite</span> stability field as the result of pressure and temperature decrease. As comparisons with mantle xenoliths show, the Zabargad ultramafites are not ophiolithes but rather, represent the fertile upper mantle. Results indicate, in concordance with previous papers such as Bonatti et al., 1981 and Kurat et al., 1993, that the studied peridotite represents an uplifted fragment of the Red Sea upper mantle which is also evidence for the Red Sea rifting and the formation of the island itself.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMDI21A4258B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMDI21A4258B"><span id="translatedtitle">Partial Melting of Garnet <span class="hlt">Lherzolite</span> with H2o and CO2 at 3 GPa: Implications for Intraplate Magmatism.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Baasner, A.; Medard, E.; Laporte, D.</p> <p>2014-12-01</p> <p>The origin and source rock of alkali-rich and SiO2-undersatured magmas in the Earth`s upper mantle have been under debate for a long time. The garnet signature in rare earth element patterns of such magmas suggest a garnet-bearing source rock, which could be garnet <span class="hlt">lherzolite</span> or garnet pyroxenite. Partial melting experiments were performed at 3 GPa and 1345-1445 °C in a piston-cylinder apparatus using mixtures of natural <span class="hlt">lherzolite</span> with 0.4-0.7 wt% H2O and 0.4-0.7 wt% CO2 as starting materials. Different designs of AuPd capsules were used for melt extraction. Mineral and melt phases were analysed with electron microprobe and laser ablation inductively coupled plasma mass spectrometry. The degree of partial melting in the experiments ranges from ~20% to ~4% and decreases with decreasing temperature and decreasing volatile content in the starting material. All samples contain olivine and orthopyroxene. Garnet is present in experiments performed below 1420 °C. The amount of clinopyroxene decreases with increasing degree of partial melting and volatile concentration in the starting material. Depending on the capsule design the melts quenched to glasses or to a mixture of quench crystals and residual glass. The composition of the partial melts ranges from basalts through picrobasalts to foidites. The alkali concentration increases and the SiO2 concentration decreases with decreasing degree of partial melting and increasing volatile concentration in the starting material. The partial melts are similar in many aspects to alkali intraplate magmas (basanites to melilitites), although they are richer in MgO. Compositions closer to natural basanites could be obtained either at lower degree of melting (and lower volatile contents) or through olivine fractionation. Our results strongly suggests that. SiO2-undersaturated intraplate magmas can be generated by mantle melting of garnet-<span class="hlt">lherzolite</span> in the presence of H2O and CO2 in the Earth`s upper mantle at 3 GPa (~100 km depth).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1987CoMP...97..473C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1987CoMP...97..473C"><span id="translatedtitle">Garnet <span class="hlt">lherzolite</span> xenoliths in the kimberlites of northern Lesotho: revised P-T equilibration conditions and upper mantle Palaeogeotherm</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Carswell, D. A.; Gibb, F. G. F.</p> <p>1987-12-01</p> <p>Evidence is presented that the inflected palaeogeotherm for northern Lesotho, previously highlighted by Boyd (1973), Boyd and Nixon (1973, 1975), Finnerty and Boyd (1984, 1987), is essentially an artifact of the unsatisfactory, over-simplified barometer formulation (based on MacGregor 1974) employed. The absence of an inflection in the palaeogeotherm for Udachnaya, Siberia based on P-T estimates for garnet <span class="hlt">lherzolite</span> xenoliths calculated with the same barometer, does not prove the reality of an inflected palaeogeotherm for northern Lesotho. Rather, it reflects, at least in part, chemical differences between the equivalent deformed, high- T xenoliths in these two areas — most importantly expressed in the respective contents of Jadeite relative to ureyite in the constituent orthopyroxenes. Accurate estimation of P-T equilibration conditions for garnet <span class="hlt">lherzolite</span> xenoliths requires both complete and precise mineral analyses and adequate consideration of the influence of minor elements, such as Cr and Na, on the element exchange reaction thermometers and barometers employed. The barometer formulation of Nickel and Green (1985) is judged to be the best currently available. As no single thermometer is entirely satisfactory and dependable throughout the P-T range of interest, equilibration temperatures are currently best assessed as a mean value obtained from application of the most accurate formulations for both the two-pyroxene solvus thermometer (Bertrand and Mercier 1985) and Fe2+-Mg2+ exchange reactions between garnet-clinopyroxene (Powell 1985), garnet-orthopyroxene (Harley 1984a) and garnet-olivine (O'Neill and Wood 1979) mineral pairs. Such ‘best’ P-T estimates for xenoliths in the kimberlites of northern Lesotho indicate a somewhat elevated, non-inflected, upper mantle palaeogeotherm, compatible with a 120 145 km thick thermally conductive lithosphere above a convecting asthenosphere. The common coarse textured, chemically depleted, garnet <span class="hlt">lherzolite</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20060049101&hterms=Host&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DHost','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20060049101&hterms=Host&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DHost"><span id="translatedtitle">Oxygen-isotopic Compositions of Relict and Host Grains in Chondrules in the <span class="hlt">Yamato</span> 81020 CO3.0 Chondrite</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kunihiro, Takuya; Rubin, Alan E.; McKeegan, Kevin D.; Wasson, John T.</p> <p>2006-01-01</p> <p>We report the oxygen-isotope compositions of relict and host olivine grains in six high-FeO porphyritic olivine chondrules in one of the most primitive carbonaceous chondrites, CO3.0 <span class="hlt">Yamato</span> 81020. Because the relict grains predate the host phenocrysts, microscale in situ analyses of O-isotope compositions can help assess the degree of heterogeneity among chondrule precursors and constrain the nebular processes that caused these isotopic differences. In five of six chondrules studied, the DELTA O-17 (=delta O-17 - 0.52 (raised dot) delta O-18) compositions of host phenocrysts are higher than those in low-FeO relict grains; the one exception is for a chondrule with a moderately high-FeO relict. Both the fayalite compositions as well as the O-isotope data support the view that the low-FeO relict grains formed in a previous generation of low-FeO porphyritic chondrules that were subsequently fragmented. It appears that most low-FeO porphyritic chondrules formed earlier than most high-FeO porphyritic chondrules, although there were probably some low-FeO chondrules that formed during the period when most high-FeO chondrules were forming.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140000409','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140000409"><span id="translatedtitle">Ar-Ar and Rb-Sr Ages of the Tissint Olivine-phyric Martian <span class="hlt">Shergottite</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Park, J.; Herzog, G. F.; Nyquist, L. E.; Shih, C.-Y.; Turin, B.; Lindsay, F. N.; Delaney, J. S.; Swisher, C. C., III; Agee, C.</p> <p>2013-01-01</p> <p>The fifth martian meteorite fall, Tissint, is an olivine-phyric <span class="hlt">shergottite</span> that contains olivine macrocrysts (approximately 1.5 mm) [1]. [2] reported the Sm-Nd age of Tissint as 596 plus or minus 23 Ma along with Rb-Sr data that defined no isochron. [3] reported Lu-Hf and Sm-Nd ages of 583 plus or minus 86 Ma and 616 plus or minus 67 Ma, respectively. The cosmic-ray exposure ages of Tissint are 1.10 plus or minus 0.15 Ma based on 10Be [4], and 1.0-1.1 Ma, based on 3He, 21Ne, and 38Ar [5,6].We report Ar-Ar ages and Rb-Sr data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010Sci...328..347L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010Sci...328..347L"><span id="translatedtitle">A Younger Age for ALH84001 and Its Geochemical Link to <span class="hlt">Shergottite</span> Sources in Mars</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lapen, T. J.; Righter, M.; Brandon, A. D.; Debaille, V.; Beard, B. L.; Shafer, J. T.; Peslier, A. H.</p> <p>2010-04-01</p> <p>Martian meteorite ALH84001 (ALH) is the oldest known igneous rock from Mars and has been used to constrain its early history. Lutetium-hafnium (Lu-Hf) isotope data for ALH indicate an igneous age of 4.091 ± 0.030 billion years, nearly coeval with an interval of heavy bombardment and cessation of the martian core dynamo and magnetic field. The calculated Lu/Hf and Sm/Nd (samarium/neodymium) ratios of the ALH parental magma source indicate that it must have undergone extensive igneous processing associated with the crystallization of a deep magma ocean. This same mantle source region also produced the <span class="hlt">shergottite</span> magmas (dated 150 to 570 million years ago), possibly indicating uniform igneous processes in Mars for nearly 4 billion years.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/20395507','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/20395507"><span id="translatedtitle">A younger age for ALH84001 and its geochemical link to <span class="hlt">shergottite</span> sources in Mars.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lapen, T J; Righter, M; Brandon, A D; Debaille, V; Beard, B L; Shafer, J T; Peslier, A H</p> <p>2010-04-16</p> <p>Martian meteorite ALH84001 (ALH) is the oldest known igneous rock from Mars and has been used to constrain its early history. Lutetium-hafnium (Lu-Hf) isotope data for ALH indicate an igneous age of 4.091 +/- 0.030 billion years, nearly coeval with an interval of heavy bombardment and cessation of the martian core dynamo and magnetic field. The calculated Lu/Hf and Sm/Nd (samarium/neodymium) ratios of the ALH parental magma source indicate that it must have undergone extensive igneous processing associated with the crystallization of a deep magma ocean. This same mantle source region also produced the <span class="hlt">shergottite</span> magmas (dated 150 to 570 million years ago), possibly indicating uniform igneous processes in Mars for nearly 4 billion years. PMID:20395507</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140012799','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140012799"><span id="translatedtitle">Preliminary Report on U-Th-Pb Isotope Systematics of the Olivine-Phyric <span class="hlt">Shergottite</span> Tissint</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Moriwaki, R.; Usui, T.; Yokoyama, T.; Simon, J. I.; Jones, J. H.</p> <p>2014-01-01</p> <p>Geochemical studies of <span class="hlt">shergottites</span> suggest that their parental magmas reflect mixtures between at least two distinct geochemical source reservoirs, producing correlations between radiogenic isotope compositions, and trace element abundances.. These correlations have been interpreted as indicating the presence of a reduced, incompatible-element- depleted reservoir and an oxidized, incompatible-element-rich reservoir. The former is clearly a depleted mantle source, but there has been a long debate regarding the origin of the enriched reservoir. Two contrasting models have been proposed regarding the location and mixing process of the two geochemical source reservoirs: (1) assimilation of oxidized crust by mantle derived, reduced magmas, or (2) mixing of two distinct mantle reservoirs during melting. The former clearly requires the ancient martian crust to be the enriched source (crustal assimilation), whereas the latter requires a long-lived enriched mantle domain that probably originated from residual melts formed during solidification of a magma ocean (heterogeneous mantle model). This study conducts Pb isotope and U-Th-Pb concentration analyses of the olivine-phyric <span class="hlt">shergottite</span> Tissint because U-Th-Pb isotope systematics have been intensively used as a powerful radiogenic tracer to characterize old crust/sediment components in mantle- derived, terrestrial oceanic island basalts. The U-Th-Pb analyses are applied to sequential acid leaching fractions obtained from Tissint whole-rock powder in order to search for Pb isotopic source components in Tissint magma. Here we report preliminary results of the U-Th-Pb analyses of acid leachates and a residue, and propose the possibility that Tissint would have experienced minor assimilation of old martian crust.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..14.5667G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..14.5667G"><span id="translatedtitle">Phase relationships of a <span class="hlt">lherzolite</span> from the Roberts Victor Mine, South Africa: A study of chemical and physical parameters in the Kaapvaal Craton.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Globig, J.; Sommer, H.</p> <p>2012-04-01</p> <p>The Roberts Victor kimberlite pipe-dike system is well known as type locality for intensively studied eclogitic xenoliths. Since more than 95% of the Roberts Victor xenoliths are rather of eclogitic than of peridotitic type, mineralogical data of <span class="hlt">lherzolitic</span> peridotites from the mine is extremely rare. In fact, there is no detailed petrological study of peridotitic mantle xenoliths from the Roberts Victor Mine up to the present day. As the <span class="hlt">lherzolitic</span> xenolith nodules from the Roberts Victor Mine are strongly altered, due to contact with the aqueous fluid of the ascending kimberlitic melt bulk chemistry analyses result in too low SiO2 and too high MgO concentrations. Thus, Roberts Victor <span class="hlt">lherzolites</span> provide a distorted image of the sampled mantle regions. To avoid inaccuracies in composition, we used mineral analyses of the rock forming minerals from lherzolithes from the Roberts Victor Mine and implemented a planimetric method to recalculate a proper bulk rock composition that is free of volatiles and representative of a garnet <span class="hlt">lherzolite</span> from the Kaapvaal Craton. The recalculated bulk chemistry for the four-phase <span class="hlt">lherzolite</span> composition Ol-Opx-Cpx-Gt is; SiO2≈45.83 wt.%, TiO2≈0.04 wt.%, Cr2O3≈0.51 wt.%, Al2O3≈1.84 wt.%, FeO≈6.27 wt.%, MnO≈0.07 wt.%, MgO≈43.51 wt.%, CaO≈0.53 wt.%, Na2O≈0.10 wt.%. As our bulk composition fits accurately the composition range of <span class="hlt">lherzolites</span> from the Kaapvaal Craton, analysed by Carswell and Dawson (1970), it is seen to represent the chemistry of the upper mantle beneath South Africa. By the use of the Gibbs minimization software PerpleX (Connolly, 2005) we created a petrological p-T phase diagram for a water saturated <span class="hlt">lherzolite</span> from 473-2073 K and 10-100 kbar, based on the recalculated bulk composition, to estimate the proportion of <span class="hlt">lherzolite</span> in the lithospheric-asthenospheric mantle of the Kaapvaal Craton. Furthermore and more importantly, we used PerpleX to model the modal distribution of the phases Atg, Br, Chl</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19840043311&hterms=Mars+planet&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DMars%2Bplanet','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19840043311&hterms=Mars+planet&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DMars%2Bplanet"><span id="translatedtitle">Petrogenesis of the SNC (<span class="hlt">shergottites</span>, nakhlites, chassignites) meteorites - Implications for their origin from a large dynamic planet, possibly Mars</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Smith, M. R.; Laul, J. C.; Ma, M. S.; Huston, T.; Verkouteren, R. M.; Lipschutz, M. E.; Schmitt, R. A.</p> <p>1984-01-01</p> <p>Comprehensive chemical data are presented on the <span class="hlt">shergottites</span> Shergotty, Zagami, Allan Hills (ALHA) 77005, and the new member Elephant Moraine (EETA) 79001 using results of sequential instrumental and radiochemical neutron activation analysis. The close relationship of the Antarctic shergotites indicates that ALHA 77005 is a residual source produced by incongruent melting of a source similar in bulk composition to EETA 79001A and that EETA 79001B and the interstitial phases in EETA 79001A are the melts produced by such melting episodes. The large ion lithophile LIL) trace element abundanced of the <span class="hlt">shergottites</span> require variable but extensive degrees of nomodal melting of isotopically constrained parent sources. The SNG sources are consistent with their derivation by extensive fractionation of a primitive magma initially produced from a source having chondritic refractory LIL trace element abundances. Petrogenetic and age relationships among SNC meteorites suggest a single complex-provenance on a dynamic planet not unlike earth, probably Mars.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140012817','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140012817"><span id="translatedtitle">Identification of Martian Regolith Sulfur Components in <span class="hlt">Shergottites</span> Using Sulfur K Xanes and Fe/S Ratios</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Sutton, S. R.; Ross, D. K.; Rao, M. N.; Nyquist, L. E.</p> <p>2014-01-01</p> <p>Based on isotopic anomalies in Kr and Sm, Sr-isotopes, S-isotopes, XANES results on S-speciation, Fe/S ratios in sulfide immiscible melts [5], and major element correlations with S determined in impact glasses in EET79001 Lith A & Lith B and Tissint, we have provided very strong evidence for the occurrence of a Martian regolith component in some impact melt glasses in <span class="hlt">shergottites</span>. Using REE measurements by LA-ICP-MS in <span class="hlt">shergottite</span> impact glasses, Barrat and co-workers have recently reported conflicting conclusions about the occurrence of Martian regolith components: (a) Positive evidence was reported for a Tissint impact melt, but (b) Negative evidence for impact melt in EET79001 and another impact melt in Tissint. Here, we address some specific issues related to sulfur speciation and their relevance to identifying Martian regolith components in impact glasses in EET79001 and Tissint using sulfur K XANES and Fe/S ratios in sulfide immiscible melts. XANES and FE-SEM measurements in approx. 5 micron size individual sulfur blebs in EET79001 and Tissint glasses are carried out by us using sub-micron size beams, whereas Barrat and coworkers used approx. 90 micron size laser spots for LA- ICP-MS to determine REE abundances in bulk samples of the impact melt glasses. We contend that Martian regolith components in some <span class="hlt">shergottite</span> impact glasses are present locally, and that studying impact melts in various <span class="hlt">shergottites</span> can give evidence both for and against regolith components because of sample heterogeneity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003M%26PS...38.1849T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003M%26PS...38.1849T"><span id="translatedtitle">Chemical compositions of martian basalts (<span class="hlt">shergottites</span>): Some inferences on basalt formation, mantle metasomatism, and differentiation on Mars</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Treiman, A. H.</p> <p>2003-12-01</p> <p>Bulk chemical compositions of the <span class="hlt">shergottite</span> basalts provide important constraints on magma genesis and mantle processes in Mars. Abundances of many major and trace elements in the <span class="hlt">shergottites</span> covary in 2 distinct groups: Group 1 (G1) includes mostly highly incompatible elements (e.g., La, Th), and Group 2 (G2) includes mostly moderately incompatible elements (e.g., Ti, Lu, Al, Hf). Covariations of G2 elements (not necessarily linear) are consistent with partitioning between basalt magma and orthopyroxene + olivine. This fractionation represents partial melting to form the <span class="hlt">shergottites</span> and their crystallization; the restite minerals cannot include aluminous phase(s), phosphate, ilmenite, zircon, or sulfides. Overall, abundances of G1 elements are decoupled from those of G2. In graphing abundances of a G1 element against those of a G2 element, G1/G2 abundance ratios do not appear to be random but are restricted to 4 values. <span class="hlt">Shergottites</span> with a given G1/G2 value need not have the same crystallization age and need not fall on a single fractionation trajectory involving compatible elements (e.g., Ti versus Fe*). These observations imply that the G1/G2 families were established before basalt formation and suggest metasomatic enrichment of their source region (major carrier of G2 elements) by a component rich in G1 elements. Group 1 elements were efficiently separated from G2 elements very early in Mars' history. Such efficient fractionation is not consistent with simple petrogenesis; it requires multiple fractionations, "complex" petrogenetic processes, or minerals with unusual geochemistry. The behavior of phosphorus in this early fractionation event is inexplicable by normal petrogenetic processes and minerals. Several explanations are possible, including significant compatibility of P in majoritic garnet and the presence of P-bearing iron metal (or a phosphide phase) in the residual solid assemblage (carrier of G2 elements). If the latter, Mars' mantle is more</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150001926','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150001926"><span id="translatedtitle">Mineralogical Comparison of Olivine in <span class="hlt">Shergottites</span> and A Shocked L Chondrite: Implications for Shock Histories of Brown Olivine</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Takenouchi, A.; Mikouchi, T.; Yamaguchi, A.; Zolensky, M. E.</p> <p>2015-01-01</p> <p>Most Martian meteorites are heavily shocked, exhibiting numerous shock features, for example undulatory extinction of olivine and pyroxene, the presence of diaplectic glass ("maskelynite") and the formation of shock melt. Among these shock features, olivine darkening ("brown" olivine) is unique in Martian meteorites because no other meteorite group shows such a feature. Although the presence of brown olivine in <span class="hlt">shergottites</span> was reported thirty years ago, detailed observation by TEM has not been performed until the NWA 2737 chassignite was discovered, whose olivine is darkened, being completely black in hand specimen. Fe metal nano-particles were found in NWA 2737 olivine which are considered to have been formed by olivine reduction during heavy shock. Subsequently, magnetite nano-particles were also found in other Martian meteorites and the coexistence of Fe metal and magnetite nano-particles was reported in the NWA 1950 <span class="hlt">shergottite</span> and some Fe metal nano-particles were mantled by magnetite. Therefore, the formation process of nano-particles seems to be complex. Because "brown" olivine is unique to Martian meteorites, they have a potential to constrain their shock conditions. In order to better understand the shock history of Martian meteorites, we compared olivine in several <span class="hlt">shergottites</span> with that in a highly-shocked L chondrite which contains ringwoodite.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013Litho.172...61C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013Litho.172...61C"><span id="translatedtitle">Melting of plagioclase + spinel <span class="hlt">lherzolite</span> at low pressures (0.5 GPa): An experimental approach to the evolution of basaltic melt during mantle refertilisation at shallow depths</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chalot-Prat, Françoise; Falloon, Trevor J.; Green, David H.; Hibberson, William O.</p> <p>2013-07-01</p> <p>The presence of plagioclase + spinel <span class="hlt">lherzolites</span> among ocean floor samples and in some ophiolite complexes invites speculation on their origin and relationships to processes of magmatism and lithosphere refertilisation beneath mid-ocean ridges. In an experimental approach to their petrogenesis, we have determined the compositions of liquids and co-existing minerals in the six phase assemblage [liquid + olivine + orthopyroxene + clinopyroxene + plagioclase + spinel] at 0.5 GPa and 1100 °C to 1200 °C. In our experimental approach we maintained the olivine Mg# [Mg / (Mg + Fe)] close to 90 (i.e., 88.8-95.5) but varied plagioclase from anorthite to albite. The major variations in liquid compositions are related to plagioclase composition. Liquids have much lower MgO and FeO and higher SiO2 and Al2O3 than liquids in the 6-phase plagioclase + spinel <span class="hlt">lherzolite</span> at 0.75 GPa and 1 GPa. Liquids are quartz-normative (silica-oversaturated) for plagioclase that are more calcic than An40 but nepheline-normative (critically silica-undersaturated) for plagioclase that are more sodic than An25. Liquid compositions are quite unlike natural MORB glasses with similar Mg# (i.e., compatible with parental magmas from <span class="hlt">lherzolitic</span> mantle with Mg# ≈ 90). Our study provides no support for models of MORB petrogenesis which suggest extraction of near-solidus melts from plagioclase <span class="hlt">lherzolite</span> at low pressure. Similarly, referring to numerical models of melting volumes beneath mid-ocean ridges (Langmuir et al., 1992; McKenzie and Bickle, 1988) in which melt increments are calculated for different sites and these increments pooled to form MORB, our data argue that melts equilibrated with plagioclase ± spinel <span class="hlt">lherzolite</span> at < 1 GPa cannot be significant components of such ‘pooled melt’ focussed from within the melting volume. The compositions of minerals from plagioclase ± spinel <span class="hlt">lherzolite</span> at Lanzo (northern Italy; Piccardo et al., 2007) are compared with our experimental assemblages at 0</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080026094','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080026094"><span id="translatedtitle">Feldspathic Clasts in <span class="hlt">Yamato</span> 86032: Remnants of the Lunar Crust with Implications for its Formation and Impact History</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nyquist, L.; Bogard, D.; Yamaguchi, A.; Shih, C.-Y.; Ebihara, M.; Reese, Y.; Garrison, D.; Takeda, H.</p> <p>2006-01-01</p> <p><span class="hlt">Yamato</span> (Y)-86032 is a relatively large, feldspathic lunar highlands meteorite composed of a variety of highland lithologies. Low bulk contents of Th and Fe indicated that it came from a region of the moon far distant from the Procellarum KREEP Terrain (PKT) and the Apollo landing sites, perhaps from the farside. A large (5.2 x 3.6 cm) slab was cut from Y-86032 . We report results from coordinated textural, mineralogical-petrological, chemical, and isotopic studies of lithologies identified in the slab, emphasizing the results of Ar-39/Ar-40, Rb-Sr, and Sm-Nd chronological studies as well as Sm-isotopic studies. These studies characterize the history of Y-86032 and its precursors in the farside mega-regolith, leading to inferences about the formation and evolution of the lunar crust. Textural studies establish that the Y-86032 breccia is composed of a variety of highland components including feldspathic breccias, and other components, such as possible VLT mare basalts. Impact melt veins smoothly abut the other lithologies. Thus, Y-86032 experienced at least two impact events. These impacts occurred on a predominantly feldspathic protolith, which formed 4.43+/-0.03 Ga ago as determined from a Sm-Nd isochron for mineral clasts separated from the two dominant lithologies. Initial Nd-143/Nd-144 in the protolith at that time was -0.64+/-0.13 epsilon-units below Nd-143/Nd-144 in reservoirs having chondritic Sm/Nd ratios, consistent with prior fractionation of mafic cumulates from the LMO. Although the mineral chemistry of these clasts differs in detail from that of minerals in Apollo 16 Ferroan Anorthosites (FANs), the Rb-Sr studies establish that the initial Sr-87/Sr-86 in them was the same as in the FANs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFM.P51B1423S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.P51B1423S"><span id="translatedtitle">Martian Pyroxenes in the <span class="hlt">Shergottite</span> Meteorites; Zagami, SAU005, DAG476 and EETA79001</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stephen, N.; Benedix, G. K.; Bland, P.; Hamilton, V. E.</p> <p>2010-12-01</p> <p>The geology and surface mineralogy of Mars is characterised using remote sensing techniques such as thermal emission spectroscopy (TES) from instruments on a number of spacecraft currently orbiting Mars or gathered from roving missions on the Martian surface. However, the study of Martian meteorites is also important in efforts to further understand the geological history of Mars or to interpret mission data as they are believed to be the only available samples that give us direct clues as to Martian igneous processes [1]. We have recently demonstrated that the spectra of Martian-specific minerals can be determined using micro-spectroscopy [2] and that these spectra can be reliably obtained from thin sections of Martian meteorites [3]. Accurate modal mineralogy of these meteorites is also important [4]. In this study we are using a variety of techniques to build upon previous studies of these particular samples in order to fully characterise the nature of the 2 common pyroxenes found in Martian <span class="hlt">Shergottites</span>; pigeonite and augite [5], [6]. Previous studies have shown that the <span class="hlt">Shergottite</span> meteorites are dominated by pyroxene (pigeonite and augite in varying quantities) [4], [5], commonly but not always olivine, plagioclase or maskelynite/glass and also hydrous minerals, which separate the Martian meteorites from other achondrites [7]. Our microprobe study of meteorites Zagami, EETA79001, SAU005 and DAG476 in thin-section at the Natural History Museum, London shows a chemical variability within both the pigeonite and augite composition across individual grains in all thin sections; variation within either Mg or Ca concentration varies from core to rim within the grains. This variation can also be seen in modal mineralogy maps using SEM-derived element maps and the Photoshop® technique previously described [4], and in new micro-spectroscopy data, particularly within the Zagami meteorite. New mineral spectra have been gathered from the <span class="hlt">Shergottite</span> thin-sections by</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1996GeCoA..60.4241C&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1996GeCoA..60.4241C&link_type=ABSTRACT"><span id="translatedtitle">On the recent enrichment of subcontinental lithosphere: A detailed UPb study of spinel <span class="hlt">lherzolite</span> xenoliths, Yukon, Canada</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Carignan, Jean; Ludden, John; Francis, Don</p> <p>1996-11-01</p> <p>Lead strontium, and osmium isotopic data have been obtained for whole rocks and mineral separates (olivine, orthopyroxene, clinopyroxene, and spinel) for spinel <span class="hlt">lherzolite</span> xenoliths hosted by lavas of the Quaternary Alligator Lake volcanic centre, southern Yukon. Whole-rock xenolith samples display a large variation of lead concentrations, from 16 ppb for a harzburgite to up to 400 ppb for a <span class="hlt">lherzolite</span>. However, their lead isotope ratios are relatively homogeneous with 206Pb /204Pb of 19.07 ± 0.08, 207Pb /204Pb of 15.65 ± 0.07, and 208Pb /204Pb of 38.67 ± 0.17 ( n = 7). However, the 238U /204Pb ratios display a large variation, from 12.2 to 46.5, and do not correlate with indices of fertility such as calcium or aluminum content. Mineral separates yield even larger variations in lead isotopic composition and lead and uranium concentrations. Some olivine fractions have both the lowest radiogenic compositions ( 206Pb /204Pb = 18.75 ) and the lowest 238U /204Pb ratios (˜3.1). Clinopyroxenes (cpx) display the highest lead and uranium concentrations (up to 1277 ppb and 195 ppb, respectivelly) and generally similar or more radiogenic lead isotopic composition and higher 238U /204Pb ratios than their whole-rock compositions. Orthopyroxene and spinel fractions yield intermediate compositions between olivine and cpx. Although whole rocks and cpx for individual samples yield almost identical 87Sr /86Sr , the xenoliths ( n = 5) display a large variation of strontium isotopic compositions ( 87Sr /86Sr from 0.07033 to 0.7050), lead and strontium isotope ratios of cpx and the distribution of the data in a UPb isochron diagram suggest that the subcontinental lithosphere under the Yukon was affected by a recent (< ˜30 Ma) enrichment in uranium, lead, and strontium. The metasomatic fluid/magma might have had an isotopic composition close to that of some sediments in the northern Pacific Ocean. When compared to K d values reported in the literature, olivine is enriched in</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_8 --> <div id="page_9" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="161"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70017934','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70017934"><span id="translatedtitle">Evidence for a late thermal event of unequilibrated enstatite chondrites: a Rb-Sr study of Qingzhen and <span class="hlt">Yamato</span> 6901 (EH3) and Khairpur (EL6)</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Torigoye, N.; Shima, M.</p> <p>1993-01-01</p> <p>The Rb-Sr whole rock and internal systematics of two EH3 chondrites, Qingzhen and <span class="hlt">Yamato</span> 6901, and of one EL6 chondrite, Khairpur, were determined. The internal Rb-Sr systematics of the EH3 chondrites are highly disturbed. Fractions corresponding to sulfide phases show excess 87Sr, while other fractions corresponding to silicate phases produce a linear trend on a Rb-Sr evolution diagram. If these linear relations are interpreted as isochrons, the ages of the silicate phases are 2.12?? 0.23 Ga and 2.05 ??0.33 Ga with the initial Sr isotopic ratios of 0.7112 ?? 0.0018 and 0.7089 ?? 0.0032, for Qingzhen and <span class="hlt">Yamato</span> 6901, respectively. The Rb-Sr results are interpeted as indicative of a late thermal event about 2Ga ago on the parent bodies of these EH3 chondrites. These ages agree well with previously published K-Ar ages. An older isochron age of 4.481 ?? 0.036 Ga with a low initial Sr isotopic ratio of 0.69866 ?? 0.00038 was obtained for the data from silicate fractions of Khairpur, indicating early petrological equilibrium on the parent body of EL6 chondrites. -from Authors</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014EGUGA..16.5060C&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014EGUGA..16.5060C&link_type=ABSTRACT"><span id="translatedtitle">Experimental quantification of P-T conditions of mantle refertilisation at shallow depth under spreading ridges and formation of plagioclase + spinel <span class="hlt">lherzolite</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chalot-Prat, Françoise; Falloon, Trevor J.; Green, David H.</p> <p>2014-05-01</p> <p>We studied the first-order melting process of differentiation in the Earth, and the major process of rejuvenation of the upper mantle after melting related to plate spreading (Chalot-Prat et al, 2010; 2013). We conducted experiments at High Pressure (0.75 and 0.5 GPa) and High Temperature (1260-1100°C) to obtain magma compositions in equilibrium with the mineral assemblages of a plagioclase + spinel <span class="hlt">lherzolite</span>. These PT conditions prevail at 17-30km below axial oceanic spreading ridges. We used a "trial and error" approach in a system involving nine elements (Cr-Na-Fe-Ca-Mg-Al-Si-Ti-Ni). This approaches as closely as possible a natural mantle composition, Cr being a key element in the system. Our objectives were : • to determine experimentally the compositions of melts in equilibrium with plagioclase + spinel <span class="hlt">lherzolite</span>, with emphasis on the role of plagioclase composition in controlling melt compositions; • to test the hypothesis that MORB are produced at shallow depth (17-30kms) • to quantify liquid- and mantle residue compositional paths at decreasing T and low P to understand magma differentiation by "percolation-reaction" at shallow depth in the mantle; • to compare experimental mantle mineral compositions to those of re-fertilised oceanic mantle lithosphere outcropping at the axis of oceanic spreading ridges, enabling quantification of the pressure (i.e. depth) and temperature of the re-fertilisation process that leads to formation of plagioclase and indicates the minimum thickness of the lithosphere at ridge axes. In the normative basalt tetrahedron, liquids plot on two parallel cotectic lines from silica-oversaturated (basaltic andesite at 0.75 GPa or andesite at 0.5 GPa) at the calcic end to silica-undersaturated compositions (trachyte) at the sodic end. The lower the pressure, the greater the silica oversaturation. Besides the plagioclase solid solution has a dominant role in determining the solidus temperature of plagioclase + spinel <span class="hlt">lherzolites</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016CoMP..171...45B&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016CoMP..171...45B&link_type=ABSTRACT"><span id="translatedtitle">Partial melting of garnet <span class="hlt">lherzolite</span> with water and carbon dioxide at 3 GPa using a new melt extraction technique: implications for intraplate magmatism</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Baasner, Amrei; Médard, Etienne; Laporte, Didier; Hoffer, Géraldine</p> <p>2016-05-01</p> <p>The origin and source rocks of alkali-rich and SiO2-undersatured magmas in the Earth's upper mantle are still under debate. The garnet signature in rare earth element patterns of such magmas suggests a garnet-bearing source rock, which could be garnet <span class="hlt">lherzolite</span> or garnet pyroxenite. Partial melting experiments were performed at 2.8 GPa and 1345-1445 °C in a piston-cylinder using mixtures of natural <span class="hlt">lherzolite</span> with either 0.4 wt% H2O and 0.4 wt% CO2 or 0.7 wt% H2O and 0.7 wt% CO2. Different designs of AuPd capsules were used for melt extraction. The most successful design included a pentagonally shaped disc placed in the top part of the capsule for sufficient melt extraction. The degrees of partial melting range from 0.2 to 0.04 and decrease with decreasing temperature and volatile content. All samples contain olivine and orthopyroxene. The amounts of garnet and clinopyroxene decrease with increasing degree of partial melting until both minerals disappear from the residue. Depending on the capsule design, the melts quenched to a mixture of quench crystals and residual glass or to glass, allowing measurement of the volatile concentrations by Raman spectroscopy. The compositions of the partial melts range from basalts through picrobasalts to foidites. Compared to literature data for melting of dry <span class="hlt">lherzolites</span>, the presence of H2O and CO2 reduces the SiO2 concentration and increases the MgO concentration of partial melts, but it has no observable effect on the enrichment of Na2O in the partial melts. The partial melts have compositions similar to natural melilitites from intraplate settings, which shows that SiO2-undersaturated intraplate magmas can be generated by melting of garnet <span class="hlt">lherzolite</span> in the Earth's upper mantle in the presence of H2O and CO2.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21344499','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21344499"><span id="translatedtitle">Cathodoluminescence Characterization of Maskelynite and Alkali Feldspar in <span class="hlt">Shergottite</span> (Dhofar 019)</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kayama, M.; Nakazato, T.; Nishido, H.; Ninagawa, K.; Gucsik, A.</p> <p>2009-08-17</p> <p>Dhofar 019 is classified as an olivine-bearing basaltic <span class="hlt">shergottite</span> and consists of subhedral grains of pyroxene, olivine, feldspar mostly converted to maskelynite and minor alkali feldspar. The CL spectrum of its maskelynite exhibits an emission band at around 380 nm. Similar UV-blue emission has been observed in the plagioclase experimentally shocked at 30 and 40 GPa, but not in terrestrial plagioclase. This UV-blue emission is a notable characteristic of maskelynite. CL spectrum of alkali feldspar in Dhofar 019 has an emission bands at around 420 nm with no red emission. Terrestrial alkali feldspar actually consists of blue and red emission at 420 and 710 nm assigned to Al-O{sup -}-Al and Fe{sup 3+} centers, respectively. Maskelynite shows weak and broad Raman spectral peaks at around 500 and 580 cm{sup -1}. The Raman spectrum of alkali feldspar has a weak peak at 520 cm{sup -1}, whereas terrestrial counterpart shows the emission bands at 280, 400, 470, 520 and 1120 cm{sup -1}. Shock pressure on this meteorite transformed plagioclase and alkali feldspar into maskelynite and almost glass phase, respectively. It eliminates their luminescence centers, responsible for disappearance of yellow and/or red emission in CL of maskelynite and alkali feldspar. The absence of the red emission band in alkali feldspar can also be due to the lack of Fe{sup 3+} in the feldspar as it was reported for some lunar feldspars.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016M%26PS..tmp..287H&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016M%26PS..tmp..287H&link_type=ABSTRACT"><span id="translatedtitle">Postcrystallization metasomatism in <span class="hlt">shergottites</span>: Evidence from the paired meteorites LAR 06319 and LAR 12011</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Howarth, Geoffrey H.; Liu, Yang; Chen, Yang; Pernet-Fisher, John F.; Taylor, Lawrence A.</p> <p>2016-03-01</p> <p>Apatite is the major volatile-bearing phase in Martian meteorites, containing structurally bound fluorine, chlorine, and hydroxyl ions. In apatite, F is more compatible than Cl, which in turn is more compatible than OH. During degassing, Cl strongly partitions into the exsolved phase, whereas F remains in the melt. For these reasons, the volatile concentrations within apatite are predictable during magmatic differentiation and degassing. Here, we present compositional data for apatite and merrillite in the paired enriched, olivine-phyric <span class="hlt">shergottites</span> LAR 12011 and LAR 06319. In addition, we calculate the relative volatile fugacities of the parental melts at the time of apatite formation. The apatites are dominantly OH-rich (calculated by stoichiometry) with variable yet high Cl contents. Although several other studies have found evidence for degassing in the late-stage mineral assemblage of LAR 06319, the apatite evolutionary trends cannot be reconciled with this interpretation. The variable Cl contents and high OH contents measured in apatites are not consistent with fractionation either. Volatile fugacity calculations indicate that water and fluorine activities remain relatively constant, whereas there is a large variation in the chlorine activity. The Martian crust is Cl-rich indicating that changes in Cl contents in the apatites may be related to an external crustal source. We suggest that the high and variable Cl contents and high OH contents of the apatite are the results of postcrystallization interaction with Cl-rich, and possibly water-rich, crustal fluids circulating in the Martian crust.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19950047179&hterms=gases+combustion&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dgases%2Bcombustion','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19950047179&hterms=gases+combustion&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dgases%2Bcombustion"><span id="translatedtitle">Nitrogen and noble gases in a glass sample from the LEW88516 <span class="hlt">shergottite</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Becker, Richard H.; Pepin, Robert O.</p> <p>1993-01-01</p> <p>A glass separate from the LEW88516 <span class="hlt">shergottite</span> was analyzed by step-wise combustion for N and noble gases to determine whether it contained trapped gas similar in composition to the martian atmosphere-like component previously observed in lithology C of EETA79001. Excesses of Ar-40 and Xe-129 were in fact observed in this glass, although the amounts of these excesses less than or = to 20% of those seen in the latter meteorite, and are comparable to the amounts seen in whole-rock analyses of LEW88516. The isotopic composition of N in LEW88516 does not show an enrichment in delta N-15 commensurate with the amount of isotopically-heavy N expected from the noble gases excesses. One must posit some extreme assumptions about the nature of the N components present in LEW88516 in order to allow the presence of the trapped nitrogen component. Alternatively, the N has somehow been decoupled from the noble gases, and was either never present of has been lost.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013E%26PSL.366...38Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013E%26PSL.366...38Y"><span id="translatedtitle">Rb-Sr isotopic systematics of alkali-rich fragments in the <span class="hlt">Yamato</span>-74442 LL-chondritic breccia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yokoyama, Tatsunori; Misawa, Keiji; Okano, Osamu; Shih, Chi-Yu; Nyquist, Laurence E.; Simon, Justin I.; Tappa, Michael J.; Yoneda, Shigekazu</p> <p>2013-03-01</p> <p>We have undertaken mineralogical, petrographical and Rb-Sr isotopic studies on alkali-rich igneous rock fragments in the <span class="hlt">Yamato</span> (Y)-74442 LL-chondritic breccia. The fragments are a few mm in size and are composed mainly of porphyritic olivine and dendritic pyroxene set in alkali-rich groundmass glass. Minor phases include chromite, troilite and metallic nickel-iron. Bulk chemical compositions of the fragments are almost identical to the host chondrite except for a depletion of sodium and an enrichment of potassium. Isotopic analyses of nine fragments from Y-74442 yield a Rb-Sr age of 4429±54 Ma (2σ) for λ(87Rb)=0.01402 Ga-1 with an initial ratio of 87Sr/86Sr=0.7144±0.0094 (2σ). Assuming precursors of the fragments formed 4568 Ma with 87Sr/86Sr=0.69889 when the Solar System formed, a time-averaged Rb/Sr (weight) ratio of the source material for the fragments is calculated to be 2.58+0.91/-0.93. The extremely high Rb/Sr value of this source is difficult to interpret by any igneous fractionation or liquid immiscibility, but can be explained by mixing of a chondritic component with an alkali-rich component formed in the early solar nebula. In our preferred model, the alkali component with Rb/Sr≫30 would have condensed from the residual nebular gas after removal of refractory strontium and must have been isolated for a long time in a region where the temperature was sufficiently low to prevent reaction with other silicates/oxides. A mixture of the alkali component (early nebular condensates) and the ferromagnesian component could reflect flash heating induced by impact on an LL-chondritic parent body at least 4429 Ma ago, and further enrichments of rubidium and potassium relative to strontium could have occurred during this event. The resulting impact-melt rocks could have been fragmented by later impact event(s) and finally incorporated into the Y-74442 parent body. Thus, a remarkable signature of alkali enrichments both in the early solar nebula and later on</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001JGR...106..645C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001JGR...106..645C"><span id="translatedtitle">Depth variation of seismic anisotropy and petrology in central European lithosphere: A tectonothermal synthesis from spinel <span class="hlt">lherzolite</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Christensen, N. I.; Medaris, L. G., Jr.; Wang, H. F.; Jelínek, E.</p> <p>2001-01-01</p> <p>Spinel <span class="hlt">lherzolite</span> xenoliths from the Neogene Kozákov volcano in central Europe, yielding temperatures from 680°C to 1065°C and estimated to originate from depths of 32 to 70 km, provide an exceptionally continuous record of the depth variation in seismic and petrological properties of subcontinental lithospheric mantle. Extraction depths of the xenoliths and thermal history and rheological properties of the mantle have been evaluated from a tectonothermal model for basaltic underplating associated with Neogene rifting. The chemical depletion of sub-Kozákov mantle decreases with depth, the Mg number in olivine decreasing from ˜91.4 to 90.5 and the Cr number in spinel, decreasing from ˜38.9 to 14.7. Texturally, the sampled mantle consists of an equigranular upper layer (32-43 km), an intermediate protogranular layer (43-67 km), and a lower equigranular layer (below 67 km). Olivine petrofabrics show strong axis concentrations, which change with depth from orthorhombic symmetry in the equigranular upper layer to axial symmetry in the lowermost layer. Calculated compressional and shear wave anisotropies, which average 8% and 6%, respectively, show significant depth trends that correlate with variations in depth of olivine fabric strengths and symmetries. Comparisons of the xenolith anisotropies with field observations of Pn anisotropy and SKS shear wave splitting in the region suggest that foliation is horizontal in the upper layer of the lithospheric mantle and vertical in the middle and lower layers. The depth variation in mantle properties and complexity in central Europe is the result of Devonian to Early Carboniferous convergence, continental accretion, and crustal thickening, followed by Late Carboniferous to Permian extension and gravitational collapse and final modification by Neogene rifting, thinning, and magmatic heating.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1980CoMP...75..111S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1980CoMP...75..111S"><span id="translatedtitle">Phase relations in the partial melting of the Baldissero spinel-<span class="hlt">lherzolite</span> (Ivrea-Verbano zone, Western Alps, Italy)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sinigoi, Silvano; Comin-Chiaramonti, Piero; Alberti, Antonio A.</p> <p>1980-12-01</p> <p>The occurrence of various types of mobilizates in the Baldissero spinel <span class="hlt">lherzolite</span> is due to partial melting of the same body. The study of the relationships between the peridotite and its mobilizates demonstrates that olivine did not take an active part in the fusion. Estimates of the degree of partial melting vary from 10% for the average composition, to 20% for the most depleted samples. These values refer to an initial pyrolitic composition, and thus are relative, as they can vary depending on the actual primary composition. The calculated composition of the liquid generated by partial melting is quite similar to that of a picritic basalt, and is practically the same irrespective of the 10% and 20% fusion. This fact provides strong evidence that melting took place at a unique invariant point of the natural system, producing a liquid with a remarkably constant composition. Projection of the liquid in the fo-an-di-si diagram is fairly well aligned with the modal compositions of the solid residua, but does not coincide with the minimum of the simplified system. The proposed solution is based on the enlargement of the spinel field (at constant pressure), due to the Cr content in this phase. Therefore, the position of the invariant minimum is not fixed, but rather controlled by the Cr content of the spinel. Is is suggested that, by an increase in the Cr content, spinel might at a given moment become refractory. Thus, saturated or over-saturated magmas are produced depending on the phase relations between olivine, orthopyroxene and clinopyroxene. This would happen in the case of very advanced fusions or in the case of fusion of already depleted peridotites. The relationships between mobilizates of different generations suggest a non adiabatic mantle upwelling.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110007805','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110007805"><span id="translatedtitle">Recognizing the Effects of Terrestrial Contamination on D/H Ratios in <span class="hlt">Shergottite</span> Phosphates</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ross, D. K.; Ito, M.; Hervig, R.; Rao, M. N.; Nyquist, L. E.</p> <p>2011-01-01</p> <p>Hydrogen isotope ratios in <span class="hlt">shergottite</span> phosphate minerals have been investigated by SIMS in the meteorites Queen Alexandra Range (QUE) 94201 and Los Angeles. We have also collected electron probe data on these phosphates in order to characterize the phosphate minerals and attempt to document any potential hydrogen isotopic differences between chlor-apatite and whitlockite. In the section of Los Angeles we studied (748), we found both chlor-apatite and whitlockite, but in the section of QUE 94201,38 studied, we found only whitlockite. In both meteorites, D/H ratios (expressed in units of delta D (sub SMOW) vary, from terrestrial values up to approximately 5400%o in QUE 94201, and to approximately 3800%o in Los Angeles. We have carefully examined the ion probed pits with high-resolution FE-SEM. In most cases where the D/H ratios are low, we have iden-tified cracks that instersect the ion probe pit. These cracks are not visible in the optical microscope attached to the SIMS instument, making them impossible to avoid during SIMS data collection. We contend that the low ratios are a function of substantial terrestrial contamination, and that similar contamination is a likely factor in previously published studies on D/H ratios in martian phosphates. Here we highlight the difficulty of attempts to constrain the martian mantle D/H ratio using phosphate data, given that both terrestrial contamination and martian mantle hydrogen will move phosphate D/H ratios in the same direction, toward lower values. We note that our data include some of the most deuterium-rich values ever reported for martian phosphates. It is clear that some of our measurements are only minimally or totally uncontaminated, but the question arises, are intermediate values diminished because of true martian variability, or do they reflect contamination?</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20130011096','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20130011096"><span id="translatedtitle">Compositions of Magmatic and Impact Melt Sulfides in Tissint And EETA79001: Precursors of Immiscible Sulfide Melt Blebs in <span class="hlt">Shergottite</span> Impact Melts</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ross, D. K.; Rao, M. N.; Nyquist, L.; Agee, C.; Sutton, S.</p> <p>2013-01-01</p> <p>Immiscible sulfide melt spherules are locally very abundant in <span class="hlt">shergottite</span> impact melts. These melts can also contain samples of Martian atmospheric gases [1], and cosmogenic nuclides [2] that are present in impact melt, but not in the host <span class="hlt">shergottite</span>, indicating some components in the melt resided at the Martian surface. These observations show that some regolith components are, at least locally, present in the impact melts. This view also suggests that one source of the over-abundant sulfur in these impact melts could be sulfates that are major constituents of Martian regolith, and that the sulfates were reduced during shock heating to sulfide. An alternative view is that sulfide spherules in impact melts are produced solely by melting the crystalline sulfide minerals (dominantly pyrrhotite, Fe(1-x)S) that are present in <span class="hlt">shergottites</span> [3]. In this abstract we report new analyses of the compositions of sulfide immiscible melt spherules and pyrrhotite in the <span class="hlt">shergottites</span> Tissint, and EETA79001,507, and we use these data to investigate the possible origins of the immiscible sulfide melt spherules. In particular, we use the metal/S ratios determined in these blebs as potential diagnostic criteria for tracking the source material from which the numerous sulfide blebs were generated by shock in these melts.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20020046467&hterms=Gadolinium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DGadolinium','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20020046467&hterms=Gadolinium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DGadolinium"><span id="translatedtitle">An Experimental Study of Eu/Gd Partitioning Between a <span class="hlt">Shergottite</span> Melt and Pigeonite: Implications for the Oxygen Fugacity of the Martian Interior</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>McCanta, M. C.; Rutherford, M. J.; Jones, J. H.</p> <p>2002-01-01</p> <p>We experimentally investigated the partitioning behavior of Eu/Gd between a synthetic <span class="hlt">shergottite</span> melt and pigeonite as a function of oxygen fugacity. This has implications for the oxidation state of the source region of the martian meteorites. Additional information is contained in the original extended abstract.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006GeCoA..70.5990N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006GeCoA..70.5990N"><span id="translatedtitle">Feldspathic clasts in <span class="hlt">Yamato</span>-86032: Remnants of the lunar crust with implications for its formation and impact history</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nyquist, L.; Bogard, D.; Yamaguchi, A.; Shih, C.-Y.; Karouji, Y.; Ebihara, M.; Reese, Y.; Garrison, D.; McKay, G.; Takeda, H.</p> <p>2006-12-01</p> <p>Low concentrations of Th and Fe in the <span class="hlt">Yamato</span> (Y)-86032 bulk meteorite support earlier suggestions that Y-86032 comes from a region of the moon far distant from the Procellarum KREEP Terrain (PKT), probably from the lunar farside. 39Ar- 40Ar, Rb-Sr, Sm-Nd, and Sm-isotopic studies characterize the chronology of Y-86032 and its precursors in the mega regolith. One of the rock types present in a light gray breccia lithology is an anorthosite characterized by plagioclase with An ˜93, i.e., more sodic than lunar FANs, but with very low 87Rb/ 86Sr and 87Sr/ 86Sr similar to those of FANs. (FAN stands for Ferroan Anorthosite). This "An93 anorthosite" has Nd-isotopic systematics similar to those of nearside norites. A FAN-like "An97 anorthosite" is present in a second light-colored feldspathic breccia clast and has a more negative ɛNd value consistent with residence in a LREE-enriched environment as would be provided by an early plagioclase flotation crust on the Lunar Magma Ocean (LMO). This result contrasts with generally positive values of ɛNd for Apollo 16 FANs suggesting the possibility of assymetric development of the LMO. Other possible explanations for the dichotomy in ɛNd values are advanced in the text. The Y-86032 protolith formed at least 4.43 ± 0.03 Ga ago as determined from a Sm-Nd isochron for mineral fragments from the breccia clast composed predominantly of An93 anorthosite and a second clast of more varied composition. We interpret the mineral fragments as being predominatly from a cogenetic rock suite. An 39Ar- 40Ar age of 4.36-4.41 ± 0.035 Ga for a third clast composed predominantly of An97 anorthosite supports an old age for the protolith. Initial 143Nd/ 144Nd in that clast was -0.64 ± 0.13 ɛ-units below 143Nd/ 144Nd in reservoirs having chondritic Sm/Nd ratios, consistent with prior fractionation of mafic cumulates from the LMO. A maximum in the 39Ar- 40Ar age spectrum of 4.23 ± 0.03 Ga for a second sample of the same feldspathic breccia clast</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014GeoJI.197..900M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014GeoJI.197..900M"><span id="translatedtitle">The temperature dependence of thermal conductivity for <span class="hlt">lherzolites</span> from the North China Craton and the associated constraints on the thermodynamic thickness of the lithosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Miao, Sheqiang; Li, Heping; Chen, Gang</p> <p>2014-05-01</p> <p>In this study, the authors aimed to compute the lithospheric thickness beneath the North China Craton (NCC) by combining the measurement of the thermophysical properties of <span class="hlt">lherzolite</span> xenoliths from the Cenozoic basalts in North China with the corresponding geothermal data, thus providing geothermal constraints for the lithospheric thinning beneath the NCC. Based on the precise measurement of the thermal diffusivity, specific heat capacity at high temperatures, and density at room temperature for <span class="hlt">lherzolites</span> from the NCC, the temperature dependence of lattice thermal conductivity for <span class="hlt">lherzolites</span> was obtained. Combining with the surface heat flow, heat production of rocks and other relevant conditions, the average thickness of the lithosphere beneath the NCC and the lithospheric thickness of secondary massifs were computed, and we identified the relationship between depth and temperature beneath the NCC and each secondary massif. The computed lithospheric thickness is highly consistent with the results of geophysical observations. The computation results of this study indicate that the average lithospheric thickness of the current NCC and the average thickness of the eastern NCC were 101 and 75 km, the lithospheric thickness of the Ordos block increases from 110 km in the east to approximately 200 km in the west, and the average thickness is 141 km, that were thinner than that in the Archean era (200 km) by approximately 100, 125 and 60 km. These results reveal that, in addition to eastern NCC, the Taihang orogenic belt and Ordos block have also experienced varying degrees of thinning with a thinning centre oriented in the north-south direction, consistent with the direction of the thinning centre along the Tanlu fault zone beneath the east NCC.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003EAEJA.....8111L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003EAEJA.....8111L"><span id="translatedtitle">The effects of small amounts of H2O on partial melting of model spinel <span class="hlt">lherzolite</span> in the system CMAS</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, X.; St. C. Oneill, H.</p> <p>2003-04-01</p> <p>Water (H_2O) is so effective at lowering the solidus temperatures of silicate systems that even small amounts of H_2O are suspected to be important in the genesis of basaltic magmas. The realization that petrologically significant amounts of H_2O can be stored in nominally anhydrous mantle minerals (olivine and pyroxenes) has fundamental implications for the understanding of partial melting in the mantle, for it implies that the role that H_2O plays in mantle melting may not be appropriately described by models in which the melting is controlled by hydrous phases such as amphibole. Although the effect of water in suppressing the liquidus during crystallization is quite well understood, such observations do not provide direct quantitative information on the solidus. This is because liquidus crystallization occurs at constant major-element composition of the system, but at unbuffered component activities (high thermodynamic variance). By contrast, for partial melting at the solidus the major-element component activities are buffered by the coexisting crystalline phases (low variance), but the major-element composition of the melt can change as a function of added H_2O. Accordingly we have determined both the solidus temperature and the melt composition in the system CMAS with small additions of H_2O, to 4 wt%, in equilibrium with the four-phase <span class="hlt">lherzolite</span> assemblage of fo+opx+cpx+sp. Experiments were conducted at 1.1 GPa and temperatures from 1473 K to the dry solidus at 1593 K in a piston-cylinder apparatus. Starting materials were pre-synthesised assemblage of fo+opx+cpx+sp, plus an oxide/hydroxide mix of approximately the anticipated melt composition. H_2O was added as either Mg(OH)_2 or Al(OH)_3. The crystalline assemblage and melt starting mix were added as separate layers inside sealed Pt capsules, to ensure large volumes of crystal-free melt. After the run doubly polished sections were prepared in order to analyse the quenched melt by FTIR spectroscopy, to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150002838','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150002838"><span id="translatedtitle">Gusev-Meridiani-Type Soil Component Dissolved in Some Shock Glasses in <span class="hlt">Shergottites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ross, D. K.; Rao, M. N.; Nyquist, L. E.; Shi, C. Y.; Sutton, S.; Harrison, D. H.</p> <p>2015-01-01</p> <p>Modal analysis, based on APXS, MiniTES and Mossbauer results obtained at Gusev and Meridiani sites on Mars, indicates that Martian soils consist predominantly of igneous minerals such as olivine, pyroxene and feldspar (approximately70 - 80%), with the balance consisting of alteration minerals such as sulfates, silica and chlorides]. These studies also showed that soil alteration did not occur in-situ and igneous and alteration components are derived from different sources. Below, we analyse the chemical abundance data obtained from shock glasses in <span class="hlt">shergottites</span> using mass balance mixing models. In these models, the two main end members used are (a) host rock chemical composition and (b) the GM soils average composition as the second component. Here, we consider the S-bearing phases as indicators of added alteration phases in the shock glasses and GM soils. Although the S-bearing phase in shock glasses occurs as micron sized sulfide blebs, we showed in earlier abstracts that sulfur was originally present as sulfate in impact glass-precursor materials and was subsequently reduced to sulfide during shock melting. This conclusion is based on results obtained from S-K XANES studies, Fe/S atomic ratios in sulfide blebs and 34S/32S isotopic measurements in these sulfide blebs. Additionally, sulfur in several EET79001 Lith. A glasses is found to correlate positively with Al2O3 and CaO (and negatively with FeO and MgO), suggesting the presence of Al- and Ca- sul-fate-bearing phases. The distribution of the 87Sr/86Sr iso-topic ratios determined in Lith. A glasses (,27 &,188 and,54) indicate that Martian soil gypsum and host rock material were mixed with each other in the glass precursors. In some vugs in Lith A glass,27 detected gypsum laths. Furthermore, the Martian regolith-de-rived component (where sulfur typically occurs as sul-fate) is identified in these glasses by determining neutron produced isotopic excesses/deficits in 80Kr and 149Sm isotopes. Moreover, the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.P43D4010B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.P43D4010B"><span id="translatedtitle">Comparing MSL ChemCam Analyses to <span class="hlt">Shergottite</span> and Terrestrial Rock Types</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bridges, J.; Edwards, P.; Dyar, M. D.; Fisk, M. R.; Schwenzer, S. P.; Forni, O.; Wiens, R. C.</p> <p>2014-12-01</p> <p>The ChemCam instrument on Mars Science Laboratory determines the elemental composition of target areas at ≤6m range, and has acquired over 145000 spectra. Here we use the individual shots and averaged targets with the PLS1 dataset on both outcrops and float rocks. Various localities were sampled, including Rocknest, Sheepbed, Shaler, Cooperstown, Darwin and Kimberley. Rocknest and Sheepbed shots have quite homogeneous, basaltic compositions with Gini factors of 0.66 and 0.67 respectively (a Gini factor of 0 indicates a completely homogeneous dataset). Shaler is similarly homogeneous with a Gini factor 0.62 but is more felsic in composition. Darwin and Kimberley both follow a basaltic mixing trend between pyroxene and alkali feldspars. They have a heterogeneous spread with factors of 0.77 and 0.74. Kimberley and Darwin are the most alkaline outcrops, and then Shaler, finally Sheepbed and Rocknest are the least alkaline. The Na2O and K2O contents are controlled by variable abundances of alkaline feldspars. Many float rocks were also analysed. They include samples with mm-sized, visible feldspar grains, which are probable phenocrysts and cumulate grains. These rocks likely come from different sources as their compositions are quite heterogeneous e.g. the Gini factor for the whole set of feldspar-rich float rocks is 0.76 (using an average composition for each target). We compare these compositions with data from the MER APXS, and from this we can see that the float rocks sampled by MSL are closer to the alkaline feldspar end of the basaltic mixing trend than the more FeO+MgO-rich MER basalts (e.g. Rieder et al. 2004 10.1126/science.1104358) The basaltic <span class="hlt">shergottite</span> meteorites also have higher FeO+MgO contents and lower Al2O3 than the MSL rocks. When compared on Al2O3-(FeOMgO)-(Na2OK2O)-CaO and other plots, the float rocks have compositions similar to a spread between terrestrial diorite and gabbro, though some have high Na2O+K2O contents.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.V52B..03M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.V52B..03M"><span id="translatedtitle">Fe3+ partitioning during basalt differentiation on Mars: insights into the oxygen fugacity of the <span class="hlt">shergottite</span> mantle source(s).</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Medard, E.; Martin, A. M.; Collinet, M.; Righter, K.; Grove, T. L.; Newville, M.; Lanzirotti, A.</p> <p>2014-12-01</p> <p>The partitioning of Fe3+ between silicate melts and minerals is a key parameter to understand magmatic processes, as it is directly linked to oxygen fugacity (fO2). fO2 is, a priori, not a constant during magmatic processes, and its evolution depends on the compatibility of Fe3+. We have experimentally determined the partition coefficients of Fe3+ between augite, pigeonite, and silicate melt, and use them to constrain the fO2of the martian mantle and of differentiated martian basalts. A series of experiments on various martian basaltic compositions were performed under controlled fO2 in one-atmosphere gas-mixing furnaces. Fe3+/Fetotal ratios in silicate melts and pyroxenes were determined using synchrotron Fe K-edge XANES on the 13 IDE beamline at APS (Argonne). Fe3+ mineral/melt partition coefficients (DFe3+) for augite and pigeonite were obtained with a relative uncertainty of 10-15 %. Both are constant over a wide range of oxygen fugacity (FMQ-2.5 to FMQ+2.0). DFe3+ for augite and pigeonite are broadly consistent with previous data by [1], but DFe3+ for augite is significantly higher (by a factor of 2) than the indirect determinations of [2]. Since augites in [2] are extremely poor in iron compared to ours (0.18 wt% vs 13 wt% FeO), this strongly suggests that DFe3+ varies with Mg#, indicating that Fe3+is more compatible than previously thought in terrestrial mantle pyroxenes (3 wt% FeO) as well. Crystallization paths for <span class="hlt">shergottite</span> parental melts have been calculated using the MELTS software, combined with our partition coefficients. fO2 in the residual melts is calculated from the models of [3] and [4]. It stays relatively constant at high temperatures, but increases very strongly during the latest stages of crystallization. These results explain the large range of fO2 determined in enriched <span class="hlt">shergottites</span>. In order to estimate the fO2 of the martian mantle, only the highest temperature phases in the most primitive martian samples should be used. The most</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016DokES.467..303K&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016DokES.467..303K&link_type=ABSTRACT"><span id="translatedtitle">Composition of a carbonatitic melt in equilibrium with <span class="hlt">lherzolite</span> at 5.5-6.3 GPa and 1350°C</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kruk, A. N.; Sokol, A. G.; Chebotarev, D. A.; Palyanov, Yu. A.; Sobolev, N. V.</p> <p>2016-03-01</p> <p>Generation of ultra-alkaline melts by the interaction of <span class="hlt">lherzolite</span> with cardonatites of various genesis was simulated at the P- T parameters typical of the base of the subcratonic lithosphere. Experiments with a duration of 150 h were performed at 5.5 and 6.3 GPa and 1350°C. The concentrations of CaO and MgO in melts are buffered by the phases of peridotite, and the concentrations of alkalis and FeO depend on the composition of the starting carbonatite. Melts are characterized by a low (<7 wt %) concentration of SiO2 and Ca# from 0.40 to 0.47. It is demonstrated that only high-Mg groups of carbonatitic inclusions in fibrous diamonds have a composition close to that of carbonatitic melts in equilibrium with <span class="hlt">lherzolite</span>. Most likely, the formation of kimberlite-like melts relatively enriched in SiO2 requires an additional source of heat from mantle plumes and probably H2O fluid.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015DokES.460..123S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015DokES.460..123S"><span id="translatedtitle">Mantle sources of quaternary volcanism on Zhokhov Island (De Long Islands, East Arctic): Isotope-geochemical features of the basalts and spinel <span class="hlt">lherzolite</span> xenoliths</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sakhno, V. G.; Krymsky, R. Sh.; Belyatsky, B. V.; Shevchenko, S. S.; Sergeev, S. A.</p> <p>2015-02-01</p> <p>This paper reports the results of isotope-geochemical studies and distribution patterns for trace elements and rare earth elements in a collection of specimens of Cenozoic alkaline olivine basalts and spinel <span class="hlt">lherzolite</span> xenoliths sampled at Zhokhov Island, De Long Archipelago (New Siberian Islands), East Arctic. In spite of various contributions of xenogenic minerals of mantle <span class="hlt">lherzolite</span> xenoliths (olivine, pyroxene and spinel), the bulk-rock isotope composition of the studied specimens deviates within insignificant limits. This evidences the isotopic and geochemical homogeneity of the mantle source and the absence of a significant effect of processes of contamination by crustal host rocks, which frequently occur within the basalts as xenoliths. On the other hand this reflects the short lifetime of existence and evolution of the mantle melt source. The studied basalts by their isotope and geochemical characteristics resemble volcanics of oceanic islands, intraplate continental volcanics, and those of ocean rises, relate to the activity of mantle plumes. The lack of elevated U/Pb in the studied specimens permits us to correlate the occurrence of the Cenozoic volcanism at De Long Islands of East Arctic with intraplate continental plume volcanism of the rifting stage (analogous to plume magmatism of the East African Rift, Mesozoic alkaline ultramafic volcanism of Eastern India, and others).</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_9 --> <div id="page_10" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="181"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19910025973&hterms=Cerium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DCerium','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19910025973&hterms=Cerium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DCerium"><span id="translatedtitle">Rare earth elements in minerals of the ALHA77005 <span class="hlt">shergottite</span> and implications for its parent magma and crystallization history</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lundberg, Laura L.; Crozaz, Ghislaine; Mcsween, Harry Y., Jr.</p> <p>1990-01-01</p> <p>Analyses of mineral REE and selected minor and trace elements were carried out on individual grains of pyroxenes, whitlockite, maskelynite, and olivine of the Antarctic <span class="hlt">shergottite</span> ALHA77005, and the results are used to interpret its parent magma and crystallization history. The results of mineral compositions and textural observations suggest that ALHA77005 is a cumulate with about half cumulus material (olivine + chromite) and half postcumulus phases. Most of the REEs in ALHA77005 reside in whitlockite whose modal concentration is about 1 percent. Mineral REE data support previous suggestions that plagioclase and whitlockite crystallized late, and that low-Ca pyroxene initiated crystallization before high-Ca pyroxene. The REE patterns for the intercumulus liquid, calculated from distribution coefficients for ALHA77005 pyroxene, plagioclase, and whitlockite, are in very good agreement and are similar to that of Shergotty.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012E%26PSL.341..195N&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012E%26PSL.341..195N&link_type=ABSTRACT"><span id="translatedtitle">U-Pb isotopic systematics of shock-loaded and annealed baddeleyite: Implications for crystallization ages of Martian meteorite <span class="hlt">shergottites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Niihara, Takafumi; Kaiden, Hiroshi; Misawa, Keiji; Sekine, Toshimori; Mikouchi, Takashi</p> <p>2012-08-01</p> <p>Shock-recovery and annealing experiments on basalt-baddeleyite mixtures were undertaken to evaluate shock effects on U-Pb isotopic systematics of baddeleyite. Shock pressures up to 57 GPa caused fracturing of constituent phases, mosaicism of olivine, maskelynitization of plagioclase, and melting, but the phase transition from monoclinic baddeleyite structure to high-pressure/temperature polymorphs of ZrO2 was not confirmed. The U-Pb isotopic systems of the shock-loaded baddeleyite did not show a large-scale isotopic disturbance. The samples shock-recovered from 47 GPa were then employed for annealing experiments at 1000 or 1300 °C, indicating that the basalt-baddeleyite mixture was almost totally melted except olivine and baddeleyite. Fine-grained euhedral zircon crystallized from the melt was observed around the relict baddeleyite in the sample annealed at 1300 °C for 1 h. The U-Pb isotopic systems of baddeleyite showed isotopic disturbances: many data points for the samples annealed at 1000 °C plotted above the concordia. Both radiogenic lead loss/uranium gain and radiogenic lead gain/uranium loss were observed in the baddeleyite annealed at 1300 °C. Complete radiogenic lead loss due to shock metamorphism and subsequent annealing was not observed in the shock-loaded/annealed baddeleyites studied here. These results confirm that the U-Pb isotopic systematics of baddeleyite are durable for shock metamorphism. Since <span class="hlt">shergottites</span> still preserve Fe-Mg and/or Ca zonings in major constituent phases (i.e. pyroxene and olivine), the shock effects observed in Martian baddeleyites seem to be less intense compared to that under the present experimental conditions. An implication is that the U-Pb systems of baddeleyite in <span class="hlt">shergottites</span> will provide crystallization ages of Martian magmatic rocks.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19860063595&hterms=Igneous+rocks&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3D%2528Igneous%2Brocks%2529','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19860063595&hterms=Igneous+rocks&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3D%2528Igneous%2Brocks%2529"><span id="translatedtitle">A discussion of isotopic systematics and mineral zoning in the <span class="hlt">shergottites</span> - Evidence for a 180 m.y. igneous crystallization age</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Jones, J. H.</p> <p>1986-01-01</p> <p>The chronologies of the Shergotty, Zagami, ALHA 77005, and EETA 79001 meteorites were reexamined on the basis of <span class="hlt">shergottites</span>' 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 <span class="hlt">shergottites</span> represent the youngest known extraterrestrial basalts. This conclusion supports the hypothesis that the SNC meteorites are samples of Mars.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140011731','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140011731"><span id="translatedtitle">Sm-Nd and Rb-Sr Isotopic Systematics of a Heavily Shocked Martian Meteorite Tissint and Petrogenesis of Depleted <span class="hlt">Shergottites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Shih, C.-Y.; Nyquist, L. E.; Park, J.; Agee, Carl B.</p> <p>2014-01-01</p> <p>Tissint is a very fresh Martian meteorite that fell near the town of Tissint in Morocco on July 18, 2011. It contains abundant olivine megacrysts (23%) in a fine-grained matrix of pyroxene (55%), maskelynitized plagioclase (15%), opaques (4%) and melt pockets (3%) and is petrographically similar to lithologies A and C of picritic <span class="hlt">shergottite</span> EETA 79001 [1,2]. The presence of 2 types of shock-induced glasses and all 7 high-pressure mineral phases that were ever found in melt pockets of Martian meteorites suggests it underwent an intensive shock metamorphism of 25 GPa and 2000 C localized in melt pockets [2]. Mineral textures suggest that olivines, pyroxenes and plagioclases probably did not experience such hightemperature. Earlier determinations of its age yielded 596+/-23 Ma [3] and 616+/-67 Ma [4], respectively, for the Sm-Nd system and 583+/-86 Ma for the Lu-Hf system [4], in agreement with the 575+/-18 Ma age of the oldest olivine-phyric depleted <span class="hlt">shergottite</span> Dho 019 [5]. However, the exposure ages of Tissint (1 Ma [1, 6, 7]) and Dho 019 (20 Ma [8]) are very different requiring two separate ejection events. These previously determined Sm-Nd and Lu-Hf ages are older than the Ar-Ar maskelynite plateau age of 524+/-15 Ma [9], reversing the pattern usually observed for Martian meteorites. In order to clarify these age issues and place models for Tissint's petrogenesis on a firm basis, we present new Rb-Sr and Sm- Nd isotopic results for Tissint, and discuss (a) the shock effects on them and the Ar-Ar chronometer, (b) correlation of the determined ages with those of other depleted <span class="hlt">shergottites</span>, and (c) the petrogenesis of depleted <span class="hlt">shergottites</span>. Since the meteorite is a recent fall, terrestrial contamination is expected to be minimal, but, the strong shock metamorphism might be expected to compromise the equilibrium of the isotopic systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19940016384&hterms=similarity&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dsimilarity','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19940016384&hterms=similarity&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dsimilarity"><span id="translatedtitle">Consortium study of lunar meteorites <span class="hlt">Yamato</span>-793169 and Asuka-881757: Geochemical evidence of mutual similarity, and dissimilarity versus other mare basalts</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Warren, Paul H.; Lindstrom, Marilyn M.</p> <p>1993-01-01</p> <p>Compositions of bulk powders and separated minerals from two meteorites derived from the mare lava plains of the Earth's Moon, <span class="hlt">Yamato</span>-793169 and Asuka-881757, indicate a remarkable degree of similarity to one another, and clearly favor lunar origin. However, these meteorites are unlike any previously studied lunar rock. In both cases, the bulk-rock TiO2 content is slightly greater than the level separating VLT from low-Ti mare basalt, yet the Sc content is much higher than previously observed except among high-Ti mare basalts. Conceivably, the Sc enrichment in A881757 reflects origin of this rock as a cumulate from a mare magma of 'normal' Sc content, but this seems unlikely. Mineral-separate data suggest that most of the Sc is in pyroxene, and a variety of evidence weighs against the cumulus hypothesis as a major cause for the high Sc. The remarkable similarity between Y793169 and A881757 suggests the possibility that they were derived from a single source crater on the Moon.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016CoMP..171...19K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016CoMP..171...19K"><span id="translatedtitle"><span class="hlt">Lherzolitic</span> versus harzburgitic garnet trends: sampling of extended depth versus extended composition. Reply to the comment by Ivanic et al. 2015</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kopylova, M.; Hill, P. J. A.; Russell, J. K.; Cookenboo, H.</p> <p>2016-02-01</p> <p>Using the Hill et al. (Contrib Mineral Petrol 169:13, 2015. doi: 10.1007/s00410-014-1102-7) modeling technique, we have tested the idea of Ivanic et al. (Contrib Mineral Petrol 164:505-520, 2012) that decompression and metamorphic re-equilibration of garnet with spinel causes garnet zoning perpendicular to the Cr-Ca harzburgitic trend in garnet composition. The modeling confirms that garnet zoning across the harzburgitic trend cannot form without spinel buffering. The harzburgitic trend is very rare because it results from extreme compositional heterogeneity of the mantle at the same depth. In contrast, the common <span class="hlt">lherzolitic</span> trend requires less diversity in the bulk composition of the mantle, as it can be established with only a few samples of metamorphically re-equilibrated mantle peridotite deriving from a variety of depths.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFM.P53A1432W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFM.P53A1432W"><span id="translatedtitle">Unique Ground-Truthing of a <span class="hlt">Shergottitic</span> Lithology as a Potential Orbital End-Member Provided by Mini-TES/MER and Laboratory TIR Data of Terrestrial Shocked Basalt</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wright, S.; Christensen, P.; Wyatt, M.</p> <p>2008-12-01</p> <p>The majority of the equatorial regions of Mars are basaltic sands labeled Surface Type 1 (ST1). This MGS TES orbital thermal infrared (TIR) end-member is often compared to laboratory TIR data of Deccan Trap flood basalt from central India. Although subtle spectral differences exist (to be shown), the two likely have similar abundances and composition of labradorite and clinopyroxenes augite and pigeonite. This has been confirmed by recent works utilizing Mini-TES data of Meridiani sands and Gusev soils (both ST1) along with data from other MER instruments. Further, the TIR spectrum of Deccan basalt from Lonar Crater, India that was shocked 20-40 GPa is an exact match to the TIR spectrum of the Los Angeles <span class="hlt">shergottite</span> in that both contain 45% maskelynite and 35% augite/pigeonite. This strengthens the comparison of ST1 to Deccan basalt and suggests that Los Angeles was ST1 bedrock before ejection. However, the TIR spectrum of ST1 and Deccan basalt both differ from the laboratory spectra of most basaltic <span class="hlt">shergottites</span>, which contain more clinopyroxene than plagioclase. Further, the <span class="hlt">shergottites</span> contain shattered clinopyroxenes and maskelynite, or plagioclase feldspar shock compressed to a diaplectic glass of plagioclase composition, that was created in the impact event that launched them from Mars. Presumably, the original basaltic bedrock from which <span class="hlt">shergottites</span> originated contain the original plagioclase feldspar and unshattered clinopyroxenes. Whereas there exists evidence for olivine and orthopyroxene on Mars, large occurrences of these CPX-rich <span class="hlt">shergottites</span> (not to be confused with pyroxenites or Nakhlites) have not been located using a laboratory TIR spectrum as an orbital end-member. However, one particular MER-B target named Bounce Rock has APXS and Mössbauer spectra similar to some <span class="hlt">shergottites</span> such as Zagami. Mineral abundances resulting from the deconvolution of the Mini-TES spectrum of Bounce Rock, where the effects of dust have been removed, are similar</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080013380','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080013380"><span id="translatedtitle">Sulfur and Iron Speciation in Gas-rich Impact-melt Glasses from Basaltic <span class="hlt">Shergottites</span> Determined by Microxanes</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Sutton, S. R.; Rao, M. N.; Nyquist, L. E.</p> <p>2008-01-01</p> <p>Sulfur is abundantly present as sulfate near Martian surface based on chemical and mineralogical investigations on soils and rocks in Viking, Pathfinder and MER missions. Jarosite is identified by Mossbauer studies on rocks at Meridian and Gusev, whereas MgSO4 is deduced from MgO - SO3 correlations in Pathfinder MER and Viking soils. Other sulfate minerals such as gypsum and alunogen/ S-rich aluminosilicates and halides are detected only in martian meteorites such as <span class="hlt">shergottites</span> and nakhlites using SEM/FE-SEM and EMPA techniques. Because sulfur has the capacity to occur in multiple valence states, determination of sulfur speciation (sulfide/ sulfate) in secondary mineral assemblages in soils and rocks near Mars surface may help us understand whether the fluid-rock interactions occurred under oxidizing or reducing conditions. To understand the implications of these observations for the formation of the Gas-rich Impact-melt (GRIM) glasses, we determined the oxidation state of Fe in the GRIM glasses using Fe K micro-XANES techniques.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.T11B2447Q','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.T11B2447Q"><span id="translatedtitle">Probing the structure of the sub-Salinia mantle lithosphere using spinel <span class="hlt">lherzolite</span> xenoliths from Crystal Knob, Santa Lucia Range, California</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Quinn, D. P.; Saleeby, J.; Ducea, M. N.; Luffi, P. I.</p> <p>2013-12-01</p> <p>We present the first petrogenetic analysis of a suite of peridotite xenoliths from the Crystal Knob volcanic neck in the Santa Lucia Range, California. The neck was erupted during the Plio-Pleistocene through the Salinia terrane, a fragment of the Late Cretaceous southern Sierra-northwest Mojave supra-subduction core complex that was displaced ~310 km in the late Cenozoic along the dextral San Andreas fault. The marginal tectonic setting makes these xenoliths ideal for testing different models of upper-mantle evolution along the western North American plate boundary. Possible scenarios include the early Cenozoic underplating of Farallon-plate mantle lithosphere nappes (Luffi et al., 2009), Neogene slab window opening (Atwater and Stock, 1998), and the partial subduction and stalling of the Monterey microplate (Pisker et al., 2012). The xenoliths from Crystal Knob are spinel <span class="hlt">lherzolites</span>, which sample the mantle lithosphere underlying Salinia, and dunite cumulates apparently related to the olivine-basalt host. Initial study is focused on the spinel <span class="hlt">lherzolites</span>: these display an allotriomorphic granular texture with anisotropy largely absent. However, several samples exhibit a weak shape-preferred orientation in elongate spinels. Within each xenolith, the silicate phases are in Fe-Mg equilibrium; between samples, Mg# [molar Mg/(Mg+Fe)*100] ranges from 87 to 91. Spinels have Cr# [molar Cr/(Cr+Al)*100] ranging from 10 to 27. Clinopyroxene Rb-Sr and Sm-Nd radiogenic isotope data show that the <span class="hlt">lherzolites</span> are depleted in large-ion lithophile (LIL) elements, with uniform enrichment in 143Nd (ɛNd from +10.3 to +11.0) and depletion in 87Sr (87/86Sr of .702). This data rules out origin in the continental lithosphere, such as that observed in xenoliths from above the relict subduction interface found at at Dish Hill and Cima Dome in the Mojave (Luffi et al., 2009). The Mesozoic mantle wedge, which is sampled by xenoliths from beneath the southern Sierra Nevada batholith</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeoOD..58....1M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeoOD..58....1M"><span id="translatedtitle">Chemical composition and osmium-isotope systematics of primary and secondary PGM assemblages from high-Mg chromitite of the Nurali <span class="hlt">lherzolite</span> massif, the South Urals, Russia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Malitch, K. N.; Anikina, E. V.; Badanina, I. Yu.; Belousova, E. A.; Pushkarev, E. V.; Khiller, V. V.</p> <p>2016-01-01</p> <p>The isotopic and geochemical characteristics of PGE mineralization in high-Mg chromitite from the banded dunite-wehrlite-clinopyroxenite complex of the Nurali <span class="hlt">lherzolite</span> massif, the South Urals, Russia is characterized for the first time. Electron microprobe analysis and LA MC-ICP-MS mass spectrometry are used for studying Cr-spinel and platinum-group minerals (PGM). Two processes synchronously develop in high-Mg chromitite subject to metamorphism: (1) the replacement of Mg-Al-rich Cr-spinel, orthopyroxene, and diopside by chromite, Cr-amphibole, chlorite, and garnet; (2) the formation of a secondary mineral assemblage consisting of finely dispersed ruthenium or Ru-hexaferrum aggregate and silicate-oxide or silicate matter on the location of primary Ru-Os-sulfides of the laurite-erlichmanite solid solution series. Similar variations of Os-isotopic composition in both primary and secondary PGM assemblages are evidence for the high stability of the Os isotope system in PGM and for the possibility of using model 187Os/188Os ages in geodynamic reconstructions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20160003470','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20160003470"><span id="translatedtitle">The Mineralogy, Geochemistry, and Redox State of Multivalent Cations During the Crystallization of Primitive <span class="hlt">Shergottitic</span> Liquids at Various (f)O2. Insights into the (f)O2 Fugacity of the Martian Mantle and Crustal Influences on Redox Conditions of Martian Magmas.</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Shearer, C. K.; Bell, A. S.; Burger, P. V.; Papike, J. J.; Jones, J.; Le, L.; Muttik, N.</p> <p>2016-01-01</p> <p>The (f)O2 [oxygen fugacity] of crystallization for martian basalts has been estimated in various studies to range from IW-1 to QFM+4 [1-3]. A striking geochemical feature of the <span class="hlt">shergottites</span> is the large range in initial Sr isotopic ratios and initial epsilon(sup Nd) values. Studies by observed that within the <span class="hlt">shergottite</span> group the (f)O2 [oxygen fugacity] of crystallization is highly correlated with these chemical and isotopic characteristics with depleted <span class="hlt">shergottites</span> generally crystallizing at reduced conditions and enriched <span class="hlt">shergottites</span> crystallizing under more oxidizing conditions. More recent work has shown that (f)O2 [oxygen fugacity] changed during the crystallization of these magmas from one order of magnitude in Y980459 (Y98) to several orders of magnitude in Larkman Nunatak 06319. These real or apparent variations within single <span class="hlt">shergottitic</span> magmas have been attributed to mixing of a xenocrystic olivine component, volatile loss-water disassociation, auto-oxidation during crystallization of mafic phases, and assimilation of an oxidizing crustal component (e.g. sulfate). In contrast to the <span class="hlt">shergottites</span>, augite basalts such as NWA 8159 are highly depleted yet appear to be highly oxidized (e.g. QFM+4). As a first step in attempting to unravel petrologic complexities that influence (f)O2 [oxygen fugacity] in martian magmas, this study explores the effect of (f)O2 [oxygen fugacity] on the liquid line of descent (LLD) for a primitive <span class="hlt">shergottite</span> liquid composition (Y98). The results of this study will provide a fundamental basis for reconstructing the record of (f)O2 [oxygen fugacity] in <span class="hlt">shergottites</span> and other martian basalts, its effect on both mineral chemistries and valence state partitioning, and a means for examining the role of crystallization (and other more complex processes) on the petrologic linkages between olivine-phyric and pyroxene-plagioclase <span class="hlt">shergottites</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/1009042','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/1009042"><span id="translatedtitle">Sulfur and iron speciation in gas-rich impact-melt glasses from basaltic <span class="hlt">shergottites</span> determined by microXANES</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Sutton, S.R.; Rao, M.N.; Nyquist, L.E.</p> <p>2008-04-28</p> <p>Sulfur and iron K XANES measurements were made on GRIM glasses from EET 79001. Iron is in the ferrous state. Sulfur speciation is predominately sulfide coordination but is Fe coordinated in Lith B and, most likely, Ca coordinated in Lith A. Sulfur is abundantly present as sulfate near Martian surface based on chemical and mineralogical investigations on soils and rocks in Viking, Pathfinder and MER missions. Jarosite is identified by Moessbauer studies on rocks at Meridian and Gusev, whereas MgSO{sub 4} is deduced from MgO-SO{sub 3} correlations in Pathfinder MER and Viking soils. Other sulfate minerals such as gypsum and alunogen/S-rich aluminosilicates and halides are detected only in martian meteorites such as <span class="hlt">shergottites</span> and nakhlites using SEM/FE-SEM and EMPA techniques. Because sulfur has the capacity to occur in multiple valence states, determination of sulfur speciation (sulfide/sulfate) in secondary mineral assemblages in soils and rocks near Mars surface may help us understand whether the fluid-rock interactions occurred under oxidizing or reducing conditions. On Earth, volcanic rocks contain measurable quantities of sulfur present as both sulfide and sulfate. Carroll and Rutherford showed that oxidized forms of sulfur may comprise a significant fraction of total dissolved sulfur, if the oxidation state is higher than {approx}2 log fO{sub 2} units relative to the QFM buffer. Terrestrial samples containing sulfates up to {approx}25% in fresh basalts from the Galapagos Rift on one hand and high sulfide contents present in oceanic basalts on the other indicate that the relative abundance of sulfide and sulfate varies depending on the oxygen fugacity of the system. Basaltic <span class="hlt">shergottites</span> (bulk) such as Shergotty, EET79001 and Zagami usually contain small amounts of sulfur ({approx}0.5%) as pyrrhotite. But, in isolated glass pockets containing secondary salts (known as GRIM glasses) in these meteorites, sulfur is present in high abundance ({approx}1-12%). To</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20040062419&hterms=location&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dlocation','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20040062419&hterms=location&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dlocation"><span id="translatedtitle">In Situ Location and Characterization of Carbon-bearing Phases in Carbonaceous Chondrites: Insights from <span class="hlt">Yamato</span> 791198, a Weakly-altered CM2 Chondrite</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Brearley, Adrian J.</p> <p>2004-01-01</p> <p>Intense studies of carbonaceous chondrites have provided remarkable insights into the behavior of carbon during the earliest stages of our solar system. This research has demonstrated that carbonaceous meteorites contain a diverse array of organic compounds, whose origins are probably the result of multiple processes that occurred in different locations including interstellar space, the solar nebula and asteroidal parent bodies [1-3]. The most abundant organic carbon component in CI1 and CM2 carbonaceous chondrites is so-called macromolecular carbon, a high molecular weight material that has some affinities to terrestrial kerogen and constitutes approximately 60-70% of the organic material in these meteorites. Although recent studies e.g. [3] have radically improved our understanding of the structural and compositional characteristics of this material, a number of key questions remain to be addressed. In particular, our knowledge of where this macromolecular material is distributed at the fine-scale within carbonaceous chondrites is scant. [4] have shown that organic material is associated with phyllosilicate-rich matrix in CM chondrites, but the detailed mineralogical associations are not well-known. Over the past 2 years, we have begun to address this question by using energy filtered transmission electron microscopy (EFTEM) to locate carbon-bearing materials in situ, focusing specifically on the CM2s. To date we have reported data on the Murchison CM2 chondrite [5], a meteorite that has experienced a modest degree of aqueous alteration. To extend our observations to other CM2 chondrites, we have examined the occurrence of carbon-bearing phases in <span class="hlt">Yamato</span> 791198. Our recent studies [5] have shown that Y-791198 is among the most weakly-altered CM chondrite currently known and hence is likely to preserve a quite primitive distribution of carbonaceous material. In this study, we present initial observations on the distribution of these materials in one fine</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016M%26PS...51..407W&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016M%26PS...51..407W&link_type=ABSTRACT"><span id="translatedtitle">Noble gases in 18 Martian meteorites and angrite Northwest Africa 7812—Exposure ages, trapped gases, and a re-evaluation of the evidence for solar cosmic ray-produced neon in <span class="hlt">shergottites</span> and other achondrites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wieler, R.; Huber, L.; Busemann, H.; Seiler, S.; Leya, I.; Maden, C.; Masarik, J.; Meier, M. M. M.; Nagao, K.; Trappitsch, R.; Irving, A. J.</p> <p>2016-02-01</p> <p>We present noble gas data for 16 <span class="hlt">shergottites</span>, 2 nakhlites (NWA 5790, NWA 10153), and 1 angrite (NWA 7812). Noble gas exposure ages of the <span class="hlt">shergottites</span> fall in the 1-6 Ma range found in previous studies. Three depleted olivine-phyric <span class="hlt">shergottites</span> (Tissint, NWA 6162, NWA 7635) have exposure ages of ~1 Ma, in agreement with published data for similar specimens. The exposure age of NWA 10153 (~12.2 Ma) falls in the range of 9-13 Ma reported for other nakhlites. Our preferred age of ~7.3 Ma for NWA 5790 is lower than this range, and it is possible that NWA 5790 represents a distinct ejection event. A Tissint glass sample contains Xe from the Martian atmosphere. Several samples show a remarkably low (21Ne/22Ne)cos ratio < 0.80, as previously observed in a many <span class="hlt">shergottites</span> and in various other rare achondrites. This was explained by solar cosmic ray-produced Ne (SCR Ne) in addition to the commonly found galactic cosmic ray-produced Ne, implying very low preatmospheric shielding and ablation loss. We revisit this by comparing measured (21Ne/22Ne)cos ratios with predictions by cosmogenic nuclide production models. Indeed, several <span class="hlt">shergottites</span>, acalpulcoites/lodranites, angrites (including NWA 7812), and the Brachina-like meteorite LEW 88763 likely contain SCR Ne, as previously postulated for many of them. The SCR contribution may influence the calculation of exposure ages. One likely reason that SCR nuclides are predominantly detected in meteorites from rare classes is because they usually are analyzed for cosmogenic nuclides even if they had a very small (preatmospheric) mass and hence low ablation loss.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015GCarp..66...41N&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015GCarp..66...41N&link_type=ABSTRACT"><span id="translatedtitle">Orthopyroxene-enrichment in the <span class="hlt">lherzolite</span>-websterite xenolith suite from Paleogene alkali basalts of the Poiana Ruscă Mountains (Romania)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nédli, Zsuzsanna; Szabó, Csaba; Dégi, Júlia</p> <p>2015-12-01</p> <p>In this paper we present the petrography and geochemistry of a recently collected <span class="hlt">lherzolite</span>-websterite xenolith series and of clinopyroxene xenocrysts, hosted in Upper Cretaceous-Paleogene basanites of Poiana Ruscă (Romania), whose xenoliths show notable orthopyroxene-enrichment. In the series a slightly deformed porphyroclastic-equigranular textured series could represent the early mantle characteristics, and in many cases notable orthopyroxene growth and poikilitic texture formation was observed. The most abundant mantle lithology, Type A xenoliths have high Al and Na-contents but low mg# of the pyroxenes and low cr# of spinel suggesting a low degree (< 10 %) of mafic melt removal. They are also generally poor in overall REE-s (rare earth elements) and have flat REY (rare earth elements+ Y) patterns with slight LREE-depletion. The geochemistry of the Type A xenoliths and calculated melt composition in equilibrium with the xenolith clinopyroxenes suggests that the percolating melt causing the poikilitization can be linked to a mafic, Al-Na-rich, volatile-poor melt and show similarity with the Late Cretaceous-Paleogene (66-72 Ma) subduction-related andesitic magmatism of Poiana Ruscă. Type B xenoliths, with their slightly different chemistry, suggest that, after the ancient depletion, the mantle went through a slight metasomatic event. A subsequent passage of mafic melts in the mantle, with similar compositions to the older andesitic magmatism of Poiana Ruscă, is recorded in the pyroxenites (Fe-rich xenoliths), whereas the megacrysts seem to be cogenetic with the host basanite. The Poiana Ruscă xenoliths differ from the orthopyroxene-enriched mantle xenoliths described previously from the Carpathian-Pannonian Region and from the Dacia block.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMDI21A4257G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMDI21A4257G"><span id="translatedtitle">Melting Processes at the Base of the Mantle Wedge: Melt Compositions and Melting Reactions for the First Melts of Vapor-Saturated <span class="hlt">Lherzolite</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Grove, T. L.; Till, C. B.</p> <p>2014-12-01</p> <p>Vapor-saturated melting experiments have been performed at pressures near the base of the mantle wedge (3.2 GPa). The starting composition is a metasomatized <span class="hlt">lherzolite</span> containing 3 wt. % H2O. Near-solidus melts and coexisting mineral phases have been characterized in experiments that span 925 to 1100 oC with melt % varying from 6 to 9 wt. %. Olivine, orthopyroxene, clinopyroxene and garnet coexist with melt over the entire interval and rutile is also present at < 1000 oC. Melt is andesitic in composition and varies from 60 wt. % SiO2 at 950 oC to 52 wt. % at 1075 oC. The Al2O3 contents of the melt are 13 to 14 wt. %, and CaO contents range from 1 and 4 wt. %. Melting is peritectic with orthopyroxene + liquid produced by melting of garnet + olivine + high-Ca pyroxene. In addition to quenched melt, we observe a quenched silicate component that is rhyolitic (>72 % SiO2) that we interpret as a precipitate from the coexisting supercritical H2O-rich vapor. Extrapolation of the measured compositional variation toward the solidus suggests that the first melt may be very SiO2 rich (i.e., granitic). We suggest that these granitic melts are the first melts of the mantle near the slab-wedge interface. As these SiO2-rich melts ascend into shallower, hotter overlying mantle, they continue to interact with the surrounding mantle and evolve in composition. These first melts may elucidate the geochemical and physical processes that accompany the beginnings of H2O flux melting.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2005AGUFM.P51A0902D&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2005AGUFM.P51A0902D&link_type=ABSTRACT"><span id="translatedtitle">Assimilation of High 18O/16O Crust by <span class="hlt">Shergottite</span>-Nakhlite-Chassigny (SNC) Magmas on Mars</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Day, J. M.; Taylor, L. A.; Valley, J. W.; Spicuzza, M. J.</p> <p>2005-12-01</p> <p>There is significant geochemical evidence for assimilation of crustal material into sub-aerial, mantle-derived, terrestrial basaltic magmas. Some of the most powerful constraints on crustal assimilation come from oxygen isotope studies, because supracrustal rocks often have distinct 18O/16O ratios resulting from interaction with Earth's hydrosphere. From a planetary perspective, studies of carbonate concretions from meteorite ALH84001 have yielded evidence for low-temperature crustal interaction at or near the surface of its putative parent body, Mars. This finding raises the possibility that crustal assimilation processes may be tracked using oxygen isotopes in combination with geochemical data of other reputed martian (SNC) meteorites. The whole-rock oxygen isotope ratios (Laser fluorination δ18O = +4.21 to +5.85‰ VSMOW) of SNC meteorites, correlate with aspects of their incompatible element chemistry. Some of the oxygen isotope variability may be explained by post-magmatic alteration on Mars or Earth; however, it appears, based on petrographic and geochemical observations, that a number of SNC meteorites, especially <span class="hlt">Shergottites</span>, retain the original whole-rock oxygen isotope values of their magmas prior to crystallisation. Correlations between oxygen isotopes and incompatible element geochemistry are consistent with assimilation of a high-18O/16O, incompatible-element rich, oxidizing crustal component by hot, mantle-derived magmas (δ18O = ~~4.2‰). A crustal component has previously been recognized from Sr-Nd-Os isotope systematics and oxygen fugacity measurements of SNC meteorites. Oxygen isotope evidence from SNC meteorites suggests high-18O/16O crustal contaminants on Mars result from low temperature (< 300°C) interaction with martian hydrosphere. The extent of apparent crustal contamination tracked by oxygen isotopes in SNC meteorites implies that the majority of martian crust may have undergone such interactions. Evidence for assimilation of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/10154294','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10154294"><span id="translatedtitle">Ga, Ca, and 3d transition element (Cr through Zn) partitioning among spinel-<span class="hlt">lherzolite</span> phases from the Lanzo massif, Italy: Analytical results and crystal chemistry</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wogelius, R.A.; Fraser, D.G.</p> <p>1994-06-01</p> <p>Ultramafic rocks exposed in Lanzo massif, Italy is a record of mantle geochemistry, melting, sub-solidus re-equilibration. Plagioclase(+ spinel)-<span class="hlt">lherzolite</span> samples were analyzed by Scanning Proton Microscopy, other techniques. Previous work postulated partial melting events and a two-stage sub-solidus cooling history; this paper notes Ga enrichment on spinel-clinopyroxene grain boundaries, high Ga and transition element content of spinel, and pyroxene zonation in Ca and Al. Trace element levels in olivine and orthopyroxene are also presented. Zoning trends are interpreted as due to diffusion during cooling. Olivine-clinopyroxene Cr and Ca exchange as well as clinopyroxene and spinel zonation trends indicate that the massif experienced at least two sub-solidus cooling episodes, one at 20 kbar to 1000 C and one at 8 kbar <750C. Ga levels in cores of Lanzo high-Cr spinels are high (82-66 ppM) relative to other mantle spinels (66-40 ppM), indicating enrichment. Ga content of ultramafic spinels apparently increases with Cr content; this may be due to: increased Ga solubility stemming from crystal chemical effects and/or higher Ga activities in associated silicate melts. Thus, during melting, high-Cr residual spinel may tend to buffer solid-phase Ga level. These spinels are not only rich in Ga and Cr (max 26.37 el. wt %), but also in Fe (max 21.07 el. wt %), Mn (max 3400 ppM), and Zn (max 2430 ppM). These enrichments are again due to melt extraction and partitioning into spinel structure. Low Ni (min 1050 ppM) levels are due to unsuccessful competition of Ni with Cr for octahedral structural sites caused by crystal field. Comparisons of change in partitioning vs Cr content among several 3d transition elements for spinels from Lanzo, other localities allow us to separate crystal field effects from bulk chemical effects and to show that in typical assemblages, inversion of olivine-spinel partition coefficient for Ni from <1 to >1 should occur at 11% el. wt. Cr in spinel.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016E%26PSL.444....1D&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016E%26PSL.444....1D&link_type=ABSTRACT"><span id="translatedtitle">Variable microstructural response of baddeleyite to shock metamorphism in young basaltic <span class="hlt">shergottite</span> NWA 5298 and improved U-Pb dating of Solar System events</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Darling, James R.; Moser, Desmond E.; Barker, Ivan R.; Tait, Kim T.; Chamberlain, Kevin R.; Schmitt, Axel K.; Hyde, Brendt C.</p> <p>2016-06-01</p> <p>The accurate dating of igneous and impact events is vital for the understanding of Solar System evolution, but has been hampered by limited knowledge of how shock metamorphism affects mineral and whole-rock isotopic systems used for geochronology. Baddeleyite (monoclinic ZrO2) is a refractory mineral chronometer of great potential to date these processes due to its widespread occurrence in achondrites and robust U-Pb isotopic systematics, but there is little understanding of shock-effects on this phase. Here we present new nano-structural measurements of baddeleyite grains in a thin-section of the highly-shocked basaltic <span class="hlt">shergottite</span> Northwest Africa (NWA) 5298, using high-resolution electron backscattered diffraction (EBSD) and scanning transmission electron microscopy (STEM) techniques, to investigate shock-effects and their linkage with U-Pb isotopic disturbance that has previously been documented by in-situ U-Pb isotopic analyses. The shock-altered state of originally igneous baddeleyite grains is highly variable across the thin-section and often within single grains. Analyzed grains range from those that preserve primary (magmatic) twinning and trace-element zonation (baddeleyite shock Group 1), to quasi-amorphous ZrO2 (Group 2) and to recrystallized micro-granular domains of baddeleyite (Group 3). These groups correlate closely with measured U-Pb isotope compositions. Primary igneous features in Group 1 baddeleyites (n = 5) are retained in high shock impedance grain environments, and an average of these grains yields a revised late-Amazonian magmatic crystallization age of 175 ± 30 Ma for this <span class="hlt">shergottite</span>. The youngest U-Pb dates occur from Group 3 recrystallized nano- to micro-granular baddeleyite grains, indicating that it is post-shock heating and new mineral growth that drives much of the isotopic disturbance, rather than just shock deformation and phase transitions. Our data demonstrate that a systematic multi-stage microstructural evolution in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.P31B1709S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.P31B1709S"><span id="translatedtitle">EBSD analysis of the <span class="hlt">Shergottite</span> Meteorites: New developments within the technique and their implication on what we know about the preferred orientation of Martian minerals</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stephen, N.; Benedix, G. K.; Bland, P.; Berlin, J.; Salge, T.; Goran, D.</p> <p>2011-12-01</p> <p>What we know about the geology and mineralogy of the Martian surface has been characterised by both the use of remote sensing techniques and the analysis of Martian meteorites. Various techniques are employed to conduct these analyses including crystallographic, geochemical and spectral measurements, all of which enable us to infer a geological history for these rocks. Several references have been made to the potential for preferred orientation of crystals within the <span class="hlt">Shergottites</span> [1] and their implication for the cooling history of the respective magmas on Mars [2]. We have already shown that a preferred orientation of the two pyroxenes, augite and pigeonite, can be seen in the Zagami meteorite using electron back-scatter diffraction (EBSD) analysis [3]. However, when compared to previous modal studies of the same meteorites [4], it becomes apparent that the current EBSD datasets for Martian meteorites are incomplete. Indexing of some minerals can be hampered by the lack of available matches within library databases for EBSD, or become difficult to resolve between minerals where crystallographic differences between similar minerals fall below the technical limitations of the instrument [3]. Recent advances in EBSD technologies combined with the simultaneous acquisition of energy-dispersive spectra (EDS) however now allow us to determine a more comprehensive set of analyses in a much shorter period of time, fully resolving even similar minerals where areas have been left with no indexing previously [5]. Preliminary investigations suggest that the new technology can successfully index >90% of the sample. The most recent EBSD analyses potentially reveals previously unseen fabrics in the meteorites alongside the EDS hyper-spectral imaging helping to resolve any unknown or questionable phases within them. In this study we will present new data from an investigation using EDS alongside EBSD analysis on 2 <span class="hlt">Shergottite</span> meteorites, SAU 005 and Zagami, to further resolve</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_10 --> <div id="page_11" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="201"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19970019937','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19970019937"><span id="translatedtitle">Constraints on Martian Differentiation Processes from Rb-Sr and Sm-Nd Isotopic Analyses of the Basaltic <span class="hlt">Shergottite</span> QUE 94201</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Borg, Lars E.; Nyquist, Larry E.; Taylor, Larry A.; Wiesmann, Henry; Shih, Chi-Y.</p> <p>1997-01-01</p> <p>Isotopic analyses of mineral, leachate, and whole rock fractions from the Martian <span class="hlt">shergottite</span> meteorite QUE 94201 yield Rb-Sr and Sm-Nd crystallization ages of 327 +/- 12 and 327 +/- 19 Ma, respectively. These ages are concordant, although the isochrons are defined by different fractions within the meteorite. Comparison of isotope dilution Sm and Nd data for the various QUE 94201 fractions with in situ ion microprobe data for QUE 94201 minerals from the literature demonstrate the presence of a leachable crustal component in the meteorite. This component is likely to have been added to QUE 94201 by secondary alteration processes on Mars, and can affect the isochrons by selectively altering the isotopic systematics of the leachates and some of the mineral fractions. The absence of crustal recycling processes on Mars may preserve the geochemical evidence for early differentiation and the decoupling of the Rb-Sr and Sm-Nd isotopic systems, underscoring one of the fundamental differences between geologic processes on Mars and the Earth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFMMR12A..03E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFMMR12A..03E"><span id="translatedtitle">Shock-Induced Melting of Maskelynite and the High-pressure Mineral Inventory of <span class="hlt">Shergottites</span>: Implications to Evaluation of the Shock History of Martian Meteorites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>El Goresy, A.</p> <p>2009-12-01</p> <p>Maskelynite [1-2] and the shock-induced melt pockets in <span class="hlt">shergottites</span> are diagnostic features evidencing a major dynamic event on their parent body, Mars. Several models have been proposed for the origin of maskelynite: shock-induced solid-state vitrification of labradorite [3-4], metastable melting and quenching at high-pressure (high-P) [5], or ductile mobilization [4, 6]. Similarly, the origin and relevance of shock-melt pockets and veins as the main locations of high-P minerals in <span class="hlt">shergottites</span> are controversial: localized formation by P-temperature (T) spikes in excess of 70-80 GPa [3, 4] or equilibrium assemblages evidencing peak-shock-P in the range of 25-35 GPa are discussed [7-10]. Crystallization ages are also controversial, with peaks at 160-190 Ma [11] and ≥ 4.1 Ga [12]: shock-induced age resetting may have been misinterpreted as igneous ages. We present ample evidence that maskelynite formed by metastable melting of plagioclase and quenching to glass at high-pressures as a result of the sluggishness of its inversion to lingunite. The direct consequence of our findings is the irrelevance of the refractive indices (RIs) of maskelynite as pressure indicators [3-4], since RIs were first established after decompression and quenching of maskelynite at its closure temperature of relaxation. We investigated the phase assemblages in Shergotty, Zagami, DAG 476, SAU 005, NWA 480, and NWA 856. Maskelynite contains the dense silica polymorph seifertite and the very dense monoclinic polymorph [8 -10]. Lingunite, CAS polymorph and Stishovite are present in shock-melt pockets [7-10]. Akimotoite, and silicate titanite were reported in shock-melt veins [13, 14]. The silicate liquids in which these dense minerals crystallized were perfect P-transmitting media, hence, contrary to [3-4], the dense minerals formed in equilibrium. The shock-induced events could be sequentially delineated commencing with the solid-state inversion to seifertite followed by pervasive melting of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013M%26PS...48.1359B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013M%26PS...48.1359B"><span id="translatedtitle">Magmatic history and parental melt composition of olivine-phyric <span class="hlt">shergottite</span> LAR 06319: Importance of magmatic degassing and olivine antecrysts in Martian magmatism</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Balta, J. Brian; Sanborn, Matthew; McSween, Harry Y.; Wadhwa, Meenakshi</p> <p>2013-08-01</p> <p>Several olivine-phyric <span class="hlt">shergottites</span> contain enough olivine that they could conceivably represent the products of closed-system crystallization of primary melts derived from partial melting of the Martian mantle. Larkman Nunatak (LAR) 06319 has been suggested to represent a close approach to a Martian primary liquid composition based on approximate equilibrium between its olivine and groundmass. To better understand the olivine-melt relationship and the evolution of this meteorite, we report the results of new petrographic and chemical analyses. We find that olivine megacryst cores are generally not in equilibrium with the groundmass, but rather have been homogenized by diffusion to Mg# 72. We have identified two unique grain types: an olivine glomerocryst and an olivine grain preserving a primary magmatic boundary that constrains the time scale of eruption to be on the order of hours. We also report the presence of trace oxide phases and phosphate compositions that suggest that the melt contained approximately 1.1% H2O and lost volatiles during cooling, also associated with an increase in oxygen fugacity upon degassing. We additionally report in situ rare earth element measurements of the various mineral phases in LAR 06319. Based on these reported trace element abundances, we estimate the oxygen fugacity in the LAR 06319 parent melt early in its crystallization sequence (i.e., at the time of crystallization of the low-Ca and high-Ca pyroxenes), the rare earth element composition of the parent melt, and those of melts in equilibrium with later formed phases. We suggest that LAR 06319 represents the product of closed-system crystallization within a shallow magma chamber, with additional olivine accumulated from a cumulate pile. We infer that the olivine megacrysts are antecrysts, derived from a single magma chamber, but not directly related to the host magma, and suggest that mixing of antecrysts within magma chambers may be a common process in Martian magmatic</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016M%26PS..tmp..325F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016M%26PS..tmp..325F"><span id="translatedtitle">Effect of chlorine on near-liquidus crystallization of olivine-phyric <span class="hlt">shergottite</span> NWA 6234 at 1 GPa: Implication for volatile-induced melting of the Martian mantle</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Farcy, Benjamin J.; Gross, Juliane; Carpenter, Paul; Hicks, Jacob; Filiberto, Justin</p> <p>2016-05-01</p> <p>Martian magmas are thought to be rich in chlorine compared with their terrestrial counterparts. Here, we experimentally investigate the effect of chlorine on liquidus depression and near-liquidus crystallization of olivine-phyric <span class="hlt">shergottite</span> NWA 6234 and compare these results with previous experimental results on the effect of chlorine on near-liquidus crystallization of the surface basalts Humphrey and Fastball. Previous experimental results showed that the change in liquidus temperature is dependent on the bulk composition of the basalt. The effect of chlorine on liquidus depression is greater for lower SiO2 and higher Al2O3 magmas than for higher SiO2 and lower Al2O3 magmas. The bulk composition for this study has lower Al2O3 and higher FeO contents than previous work; therefore, we provide additional constraints on the effect of the bulk composition on the influence of chlorine on near-liquidus crystallization. High pressure and temperature crystallization experiments were performed at 1 GPa on a synthetic basalt, of the bulk composition of NWA 6234, with 0-4 wt% Cl added to the sample as AgCl. The results are consistent with previous notions that with increasing wt% Cl in the melt, the crystallization temperature decreases. Importantly, our results have a liquidus depression ∆T (°C) from added chlorine that is consistent with the difference in bulk composition and suggest a dependence on both the bulk Al2O3 and FeO content. Our results suggest that the addition of chlorine to the Martian mantle may lower magma genesis temperatures and potentially aid in the petrogenesis of Martian magmas.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009M%26PS...44..805F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009M%26PS...44..805F"><span id="translatedtitle">40Ar-39Ar age determinations of lunar basalt meteorites Asuka 881757, <span class="hlt">Yamato</span> 793169, Miller Range 05035, La Paz Icefield 02205, Northwest Africa 479, and basaltic breccia Elephant Moraine 96008</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fernandes, Vera A.; Burgess, Ray; Morris, Adam</p> <p>2009-06-01</p> <p>40Ar-39Ar data are presented for the unbrecciated lunar basaltic meteorites Asuka (A-) 881757, <span class="hlt">Yamato</span> (Y-) 793169, Miller Range (MIL) 05035, LaPaz Icefield (LAP) 02205, Northwest Africa (NWA) 479 (paired with NWA 032), and basaltic fragmental breccia Elephant Moraine (EET) 96008. Stepped heating 40Ar-39Ar analyses of several bulk fragments of related meteorites A-881757, Y-793169 and MIL 05035 give crystallization ages of 3.763 ± 0.046 Ga, 3.811 ± 0.098 Ga and 3.845 ± 0.014 Ga, which are comparable with previous age determinations by Sm-Nd, U-Pb Th-Pb, Pb-Pb, and Rb-Sr methods. These three meteorites differ in the degree of secondary 40Ar loss with Y-793169 showing relatively high Ar loss probably during an impact event ˜200 Ma ago, lower Ar loss in MIL 05035 and no loss in A-881757. Bulk and impact melt glass-bearing samples of LAP 02205 gave similar ages (2.985 ± 0.016 Ga and 2.874 ± 0.056 Ga) and are consistent with ages previously determined using other isotope pairs. The basaltic portion of EET 96008 gives an age of 2.650 ± 0.086 Ga which is considered to be the crystallization age of the basalt in this meteorite. The Ar release for fragmental basaltic breccia EET 96008 shows evidence of an impact event at 631 ± 20 Ma. The crystallization age of 2.721 ± 0.040 Ga determined for NWA 479 is indistinguishable from the weighted mean age obtained from three samples of NWA 032 supporting the proposal that these meteorites are paired. The similarity of 40Ar-39Ar ages with ages determined by other isotopic systems for multiple meteorites suggests that the K-Ar isotopic system is robust for meteorites that have experienced a significant shock event and not a prolonged heating regime.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120001831','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120001831"><span id="translatedtitle">Laboratory Shock Experiments on Basalt - Iron Sulfate Mixes at Approximately 40-50 GPa and Their Relevance to the Martian Regolith Component Present in <span class="hlt">Shergottites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rao, M. N.; Nyquist, L. E.; Ross, D. K.; Asimow, P. D.; See, T.; Sutton, S.; Cardernas, F.; Montes, R.; Cintala, M.</p> <p>2012-01-01</p> <p>Basaltic <span class="hlt">shergottites</span> such as Shergotty, Zagami and EET79001 contain impact melt glass pockets that are rich in Martian atmospheric gases [1] and are known as gas-rich impact-melt (GRIM) glasses. These glasses show evidence for the presence of a Martian regolith component based on Sm and Kr isotopic studies [2]. The GRIM glasses are sometimes embedded with clusters of innumerable micron-sized iron-sulfide blebs associated with minor amounts of iron sulfate particles [3, 4]. These sulfide blebs are secondary in origin and are not related to the primary igneous sulfides occurring in Martian meteorites. The material comprising these glasses arises from the highly oxidizing Martian surface and sulfur is unlikely to occur as sulfide in the Martian regoilith. Instead, sulfur is shown to occur as sulfate based on APXS and Mossbauer results obtained by the Opportunity and Spirit rovers at Meridiani and Gusev [5]. We have earlier suggested that the micron-sized iron sulfide globules in GRIM glasses were likely produced by shock-reduction of iron sulfate occurring in the regolith at the time when the GRIM glasses were produced by the meteoroid impact that launched the Martian meteorites into space [6]. As a result of high energy deposition by shock (approx. 40-60 GPa), the iron sulfate bearing phases are likely to melt along with other regolith components and will get reduced to immiscible sulfide fluid under reducing conditions. On quenching, this generates a dispersion of micron-scale sulfide blebs. The reducing agents in our case are likely to be H2 and CO which were shock-implanted from the Martian atmosphere into these glasses along with the noble gases. We conducted lab simulation experiments in the Lindhurst Laboratory of Experimental Geophysics at Caltech and the Experimental Impact Laboratory at JSC to test whether iron sulfide globules can be produced by impact-driven reduction of iron sulfate by subjecting Columbia River Basalt (CRB) and ferric sulfate mixtures to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016M%26PS...51..390S&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016M%26PS...51..390S&link_type=ABSTRACT"><span id="translatedtitle">Determination of volatile concentrations in fluorapatite of Martian <span class="hlt">shergottite</span> NWA 2975 by combining synchrotron FTIR, Raman spectroscopy, EMPA, and TEM, and inferences on the volatile budget of the apatite host-magma</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>SłAby, Ewa; Koch-Müller, Monika; FöRster, Hans-Jürgen; Wirth, Richard; Rhede, Dieter; Schreiber, Anja; Schade, Ulrich</p> <p>2016-02-01</p> <p>We combined the focused ion beam sample preparation technique with polarized synchrotron-based FTIR (Fourier transform infrared) spectroscopy, laser-Raman spectroscopy, electron microprobe analysis (EMPA), and transmission electron microscope (TEM) analysis to identify and quantify structurally bound OH, F, Cl, and CO3 groups in fluorapatite from the Northwest Africa 2975 (NWA 2975) <span class="hlt">shergottite</span>. In this study, the first FTIR spectra of the OH-stretching region from a Martian apatite are presented that show characteristic OH-bands of a F-rich, hydroxyl-bearing apatite. Depending on the method of apatite-formula calculation and whether charge balance is assumed or not, the FTIR-based quantification of the incorporated OH, expressed as wt% H2O, is in variably good agreement with the H2O concentration calculated from electron microprobe data. EMP analyses yielded between 0.35 and 0.54 wt% H2O, and IR data yielded an average H2O content of 0.31 ± 0.03 wt%, consistent with the lower range determined from EMP analyses. The TEM observations implied that the volatiles budget of fluorapatite is magmatic. The water content and the relative volatile ratios calculated for the NWA 2975 magma are similar to those established for other enriched or intermediate <span class="hlt">shergottites</span>. It is difficult to define the source of enrichment: either Martian wet mantle or crustal assimilation. Comparing the environment of parental magma generation for NWA 2975 with the terrestrial mantle in terms of water content, it displays a composition intermediate between enriched and depleted MORB.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001CoMP..140..383F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001CoMP..140..383F"><span id="translatedtitle">Petrogenesis of the amphibole-rich veins from the Lherz orogenic <span class="hlt">lherzolite</span> massif (Eastern Pyrenees, France): a case study for the origin of orthopyroxene-bearing amphibole pyroxenites in the lithospheric mantle</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fabriès, J.; Lorand, J.-P.; Guiraud, M.</p> <p></p> <p>The Lherz orogenic <span class="hlt">lherzolite</span> massif (Eastern French Pyrenees) displays one of the best exposures of subcontinental lithospheric mantle containing veins of amphibole pyroxenites and hornblendites. A reappraisal of the petrogenesis of these rocks has been attempted from a comprehensive study of their mutual structural relationships, their petrography and their mineral compositions. Amphibole pyroxenites comprise clinopyroxene, orthopyroxene and spinel as early cumulus phases, with garnet and late-magmatic K2O-poor pargasite replacing clinopyroxene, and subsolidus exsolution products (olivine, spinel II, garnet II, plagioclase). The original magmatic mineralogy and rock compositions were partly obscured by late-intrusive hornblendites and over a few centimetres by vein-wallrock exchange reactions which continued down to subsolidus temperatures for Mg-Fe. Thermobarometric data and liquidus parageneses indicate that amphibole pyroxenites started to crystallize at P>=13kbar and recrystallized at P<12kbar. The high AlVI/AlIV ratio (>1) of clinopyroxenes, the early precipitation of orthopyroxene and the late-magmatic amphibole are arguments for parental melts richer in silica but poorer in water than alkali basalts. Their modelled major element compositions are similar to transitional alkali basalt with about 1-3wt% H2O. In contrast to amphibole pyroxenites, hornblendites only show kaersutite as liquidus phase, and phlogopite as intercumulus phase. They are interpreted as crystalline segregates from primary basanitic magmas (mg=0.6; 4-6wt% H2O). These latter cannot be related to the parental liquids of amphibole pyroxenites by a fractional crystallization process. Rather, basanitic liquids mostly reused pre-existing pyroxenite vein conduits at a higher structural level (P<=10kbar). A continuous process of redox melting and/or alkali melt/peridotite interaction in a veined lithospheric mantle is proposed to account for the origin of the Lherz hydrous veins. The</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6716326','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6716326"><span id="translatedtitle">Compositional evolution of high-temperature sheared <span class="hlt">lherzolite</span> PHN 1611</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Smith, D. ); Griffin, W.L.; Ryan, C.G. )</p> <p>1993-02-01</p> <p>The evolution of fertile' mantle has been studied by proton microprobe (PIXE) analysis of minerals of a high-temperature sheared xenolith from the Thaba Putsoa kimerlite in Lesotho, southern Africa. Analyzed elements include Ni, Cu, Zn, Ga, Sr, Y, and Zr. Garnets are homogeneous in Ni and Zn but have rims enriched relative to cores in Zr and Y. Compositions of olivine neoblasts define intergranular gradients of Fe, Zn, and Ni; Fe-rich olivine is relatively Zn-rich but Ni-poore. Although individual clinopyroxene grains are nearly homogeneous, clinopyroxene associated with Fe-rich olivine is relatively Fe- and Zn-rich but Sr- and Cr-poor. The trace-element abundances and compositional gradients constrain the processes of periodotite enrichment and the thermal history. Enrichment of Zr, Y, and Fe in garnet rims documents infiltration of a silica-undersaturated melt. The Fe-rich olivine compositions and the Zn and Fe gradients establish that the xenolith was sampled from near a melt conduit. Mechanical mixing of inhomogeneous peridotite and melt infiltration may have been concurrent. Because garnets appear homogeneous in Ni, mantle temperature changes affecting PHN 1611 occurred before or over a longer period than the melt infiltration. Measured and calculated abundances of many incompatible trace elements in the rock are similar to those proposed for primitive mantle. Calculated chondrite-normalized abundances of Sr, Ti, Zr, and Y are like those of appropriate REE. Enrichment processes in PHN 1611 proceeded at unusually high recorded temperature and in the apparent absence of minor phases common in lower-temperature metasomatized rocks, but similar processes may be common. In particular, mechanical mixing near mantle dikes may frequently occur. These enrichment mechanisms may produce xenolith compositions that resemble some proposed for primitive mantle but that have different implications for mantle evolution. 61 refs., 7 figs., 2 tabs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013PCM....40..425B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013PCM....40..425B"><span id="translatedtitle">Shock-induced formation mechanism of seifertite in <span class="hlt">shergottites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bläß, Ulrich W.</p> <p>2013-05-01</p> <p>The Martian meteorites Shergotty, Zagami and Dhofar 378 have been re-investigated in order to elucidate the shock-induced formation of seifertite. The occurrence of orthorhombic seifertite (α-PbO2 structured SiO2) has been confirmed for the mesostasis of Shergotty and Zagami by transmission electron microscopy with lattice parameters of a = 4.05(1) Å, b = 5.05(1) Å and c = 4.45(1) Å. Seifertite crystals are interpreted as shock-induced transformation products occurring together with maskelynite of both plagioclase and alkali-feldspar composition in a largely preserved eutectic crystallisation texture. Shock-induced microstructures in accessory minerals demonstrate that these regions cannot have been completely re-molten. No further features indicating shock-pressures above ~30 GPa are detected. Hence, seifertite must have been formed below its stability field by a fast solid-state process. Significantly higher shock-pressures of Dhofar 378 indicate an inhibition of a potential seifertite crystallisation by resulting high post-shock temperatures. Crystallographic considerations reveal that a direct formation of seifertite from a high-pressure derivate of cristobalite is possible without breaking any silicon-oxygen bonds. Important implications arise from the existence of such a non-equilibrium pathway. Inferring shock-pressures from metastably formed phases appears implausible, and the transition pressure could be even below 30 GPa. Furthermore, the transformation product is determined by the precursor phase. Epitaxial intergrowth with other silica high-pressure polymorphs should be induced by certain features of the precursor, for example, planar defects, or heterogeneous strain conditions. Due to symmetrical considerations, seifertite will get amorphous during a potential back-transformation, which provides an explanation for the formation of numerous amorphous lamellae.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20100036694','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20100036694"><span id="translatedtitle">Crystallization of the Zagami <span class="hlt">Shergottite</span>: An Experimental Study</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lofgren, Gary E.; McCoy, Timothy J.</p> <p>2000-01-01</p> <p>Spherulites are usually rounded or spherical objects found in rhyolitic obsidian. They usually comprise acicular crystals of alkali feldspar that radiate from a single point. The radiating array of crystalline fibers typically have a similar crystallographic orientation such that a branch fiber departs slightly but appreciably from that of its parent fiber. Individual fibers range from 1 to several micrometers in diameter. The spherulites most likely form by heterogeneous nucleation on microscopic seed crystals, bubbles, or some other surface at high degrees of supercooling. They grow very rapidly stabilizing their fibrous habit and typically range in size from microscopic to a few cm in diameter.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20010045297&hterms=information+age&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dinformation%2Bage','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20010045297&hterms=information+age&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dinformation%2Bage"><span id="translatedtitle">Age of EET79001B and Implications for <span class="hlt">Shergottite</span> Origins</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nyquist, L. E.; Reese, Y.; Wiesmann, H.; Shih, C.-Y.</p> <p>2001-01-01</p> <p>A precise Rb-Sr age of 174+/-3 Ma was determined for EET79001B. A Sm-Nd age of 169+/-23 Ma also was determined, but the Nd isotopic systematics are disturbed. This disturbance is attributed to incomplete isotopic equilibration during petrogenesis. Additional information is contained in the original extended abstract.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120007400','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120007400"><span id="translatedtitle">Iron Redox Systematics of <span class="hlt">Shergottites</span> and Martian Magmas</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Righter, Kevin; Danielson, L. R.; Martin, A. M.; Newville, M.; Choi, Y.</p> <p>2010-01-01</p> <p>Martian meteorites record a range of oxygen fugacities from near the IW buffer to above FMQ buffer [1]. In terrestrial magmas, Fe(3+)/ SigmaFe for this fO2 range are between 0 and 0.25 [2]. Such variation will affect the stability of oxides, pyroxenes, and how the melt equilibrates with volatile species. An understanding of the variation of Fe(3+)/SigmaFe for martian magmas is lacking, and previous work has been on FeO-poor and Al2O3-rich terrestrial basalts. We have initiated a study of the iron redox systematics of martian magmas to better understand FeO and Fe2O3 stability, the stability of magnetite, and the low Ca/high Ca pyroxene [3] ratios observed at the surface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003EAEJA....10642D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003EAEJA....10642D"><span id="translatedtitle">Chemical Alterations in Martian Meteorites from Cold and Hot Deserts</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dreibus, G.; Huisl, W.; Spettel, B.; Haubold, R.; Jagoutz, E.</p> <p>2003-04-01</p> <p>Martian meteorites (SNC) provide evidence of the magmatic fractionation processes of their parent body. As 23 of the total of 27 meteorites are finds, the influence of chemical alterations during their residence time on Earth must be considered, when interpreting the mineralogical, chemical, or isotopic features. Many basaltic <span class="hlt">shergottites</span> and nakhlites were collected both in the cold desert, Antarctica, and in hot deserts of North Africa and Asia. To detect alteration processes in the finds we have to compare their analytical data with those obtained from the very scarce falls. In this way, we find an overabundance of iodine in meteorites from Antarctica. The iodine contamination is caused by aerosols adhering to the ice. Therefore, iodine can penetrate into the meteorite during its residence in Antarctica. The iodine content measured in the Antarctic <span class="hlt">shergottites</span> varies from 0.060 to 4.6 ppm and seems to depend on their residence time on ice. The paired <span class="hlt">Yamato</span> nakhlites Y-000593 and Y-000749 recently discovered in Antarctica also reveal an iodine overabundance compared to Nakhla, which is the only fall among the nakhlites. However, in Nakhla we have another problem of alteration. Nakhla has unusually high Br and Cl concentrations which could originate from terrestrial or parent body alterations. As Cl and Br are readily extracted during water leaching experiments we favor a terrestrial contamination. A Br overabundance was also found in many olivine-rich <span class="hlt">shergottite</span> finds from hot deserts, DaG 476, Dhofar 019, and SaU 005. However, in the basaltic <span class="hlt">shergottite</span> Dhofar 378 and in the nakhlite NWA 817 [1] no Br contamination was observed. The olivine phases of the <span class="hlt">shergottites</span> seem to be preferably attacked by weathering reactions in the hot deserts. In the <span class="hlt">shergottites</span> from hot deserts, the subchondritic La/U ratios are remarkable, indicating a U contamination. All these meteorites are covered with an evaporation product, caliche. Caliche has a high content of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014M%26PS...49..346K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014M%26PS...49..346K"><span id="translatedtitle">Petrology and bulk chemistry of <span class="hlt">Yamato</span>-82094, a new type of carbonaceous chondrite</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kimura, M.; Barrat, J. A.; Weisberg, M. K.; Imae, N.; Yamaguchi, A.; Kojima, H.</p> <p>2014-03-01</p> <p>Carbonaceous chondrites are classified into several groups. However, some are ungrouped. We studied one such ungrouped chondrite, Y-82094, previously classified as a CO. In this chondrite, chondrules occupy 78 vol%, and the matrix is distinctly poor in abundance (11 vol%), compared with CO and other C chondrites. The average chondrule size is 0.33 mm, different from that in C chondrites. Although these features are similar to those in ordinary chondrites, Y-82094 contains 3 vol% Ca-Al-rich inclusions and 5% amoeboid olivine aggregates (AOAs). Also, the bulk composition resembles that of CO chondrites, except for the volatile elements, which are highly depleted. The oxygen isotopic composition of Y-82094 is within the range of CO and CV chondrites. Therefore, Y-82094 is an ungrouped C chondrite, not similar to any other C chondrite previously reported. Thin FeO-rich rims on AOA olivine and the mode of occurrence of Ni-rich metal in the chondrules indicate that Y-82094 is petrologic type 3.2. The extremely low abundance of type II chondrules and high abundance of Fe-Ni metal in the chondrules suggest reducing condition during chondrule formation. The depletion of volatile elements indicates that the components formed under high-temperature conditions, and accreted to the parent body of Y-82094. Our study suggests a wider range of formation conditions than currently recorded by the major C chondrite groups. Additionally, Y-82094 may represent a new, previously unsampled, asteroidal body.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120002806','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120002806"><span id="translatedtitle">Crystallization of <span class="hlt">Yamato</span> 980459 at 0.5 GPA: Are Residual Liquids Like QUE 94201?</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rapp, J. F.; Draper, D. S.; Mercer, C.</p> <p>2012-01-01</p> <p>The Martian basaltic meteorites Y980459 and QUE94201 (henceforth referred to as Y98 and QUE respectively) are thought to represent magmatic liquid compositions, rather than being products of protracted crystallization and accumulation like the majority of other martian meteorites. Both meteorite compositions have been experimentally crystallized at 1 bar, and liquidus phases were found to match corresponding mineral core compositions in the meteorites, consistent with the notion that these meteorites represent bona fide melts. They also represent the most primitive and most evolved basaltic martian samples, respectively. Y98 has Mg# (molar Mg/Mg+Fe) approximates 65, and lacks plagioclase; whereas QUE has Mg# approximates 40, and lacks olivine. However they share important geochemical characteristics (e.g. superchondritic CaO/Al2O3, very high epsilon(sub Nd) and low Sr-87/Sr-87) that suggest they sample a similar highly depleted mantle reservoir. As such, they represent likely endmembers of martian magmatic liquid compositions, and it is natural to seek petrogenetic linkages between the two. We make no claim that the actual meteorites themselves share a genetic link (the respective ages rule that out); we are exploring only in general whether primitive martian liquids like Y98 could evolve to liquids resembling QUE. Both experimental and computational efforts have been made to determine if there is indeed such a link. Recent petrological models at 1 bar generated using MELTS suggest that a QUE-like melt can be derived from a parental melt with a Y98 composition. However, experimental studies at 1 bar have been less successful at replicating this progression. Previous experimental crystallization studies of Y98 by our group at 0.5 GPa have produced melt compositions approaching that of QUE, although these results were complicated by the presence of small, variable amounts of H2O in some of the runs owing to the use of talc/pyrex experimental assemblies. Therefore we have repeated the four experiments, augmented with additional runs, all using BaCO3 cell assemblies, which are devoid of water, and these new experiments supersede those reported earlier. Here we report results of experiments simulating equilibrium crystallization; fractional crystallization experiments are currently underway.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20010045199&hterms=PYRRHOTITE&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DPYRRHOTITE','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20010045199&hterms=PYRRHOTITE&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DPYRRHOTITE"><span id="translatedtitle">Mineralogy and Petrology of <span class="hlt">Yamato</span> 86029: A New Type of Carbonaceous Chondrite</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Tonui, E.; Zolensky, M. E.</p> <p>2001-01-01</p> <p>Y-86029 resembles CI chondrites. Its matrix is very fine-grained. Olivine shows evidence of shock, which has rarely been observed in carbonaceous chondrites. Y-86029 experienced aqueous and thermal alteration during or after accretion in parent body. Additional information is contained in the original extended abstract.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70012220','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70012220"><span id="translatedtitle">Samarium-neodymium systematics in kimberlites and in the minerals of garnet <span class="hlt">lherzolite</span> inclusions</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Basu, A.R.; Tatsumoto, M.</p> <p>1979-01-01</p> <p>The initial ratios of neodymium-143 to neodymium-144 in kimberlites ranging in age between 90 ?? 106 to 1300 ?? 106 years from South Africa, India, and the United States are different from the corresponding ratios in the minerals of peridotite inclusions in the kimberlites but are identical to the ratios in the basaltic achondrite Juvinas at the times of emplacement of the respective kimberlite pipes. This correlation between the kimberlites and Juvinas, which represents the bulk chondritic earth in rare-earth elements, strongly indicates that the kimberlite's source in the mantle is chondritic in rare-earth elements and relatively primeval in composition. Copyright ?? 1979 AAAS.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/17790851','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/17790851"><span id="translatedtitle">Samarium-neodymium systematics in kimberlites and in the minerals of garnet <span class="hlt">lherzolite</span> inclusions.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Basu, A R; Tatsumoto, M</p> <p>1979-07-27</p> <p>The initial ratios of neodymium-143 to neodymium-144 in kimberlites ranging in age between 90 x 10(6) to 1300 x 10(6) years from South Africa, India, and the United States are different from the corresponding ratios in the minerals of peridotite inclusions in the kimberlites but are identical to the ratios in the basaltic achondrite Juvinas at the times of emplacement of the respective kimberlite pipes. This correlation between the kimberlites and Juvinas, which represents the bulk chondritic earth in rare-earth elements, strongly indicates that the kimberlite's source in the mantle is chondritic in rare-earth elements and relatively primeval in composition. PMID:17790851</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050169505','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050169505"><span id="translatedtitle">Ar-Ar Ages of Nakhlites Y000593, NWA998, and Nakhla and CRE Ages of NWA998</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Garrison, D. H.; Bogard, D. D.</p> <p>2005-01-01</p> <p>The seven known Martian nakhlites are Nakhla, Lafayette, Governador Valadares, and four recent finds from hot and cold deserts: MIL03346 from the Transantarctic Mountains, a paired group from the <span class="hlt">Yamato</span> Mountains (Y000593, Y000749, and Y000802, and two from Morocco (NWA998 and NWA817. Radiometric ages (Sm-Nd, Rb-Sr, U-Pb, and Ar-Ar) for the first three nakhlites, along with Chassigny, fall in the range of 1.19-1.37 Gyr and may suggest a common formation age. These meteorites also show very similar cosmic-ray (space) exposure ages, suggesting a single ejection event from Mars. The ages for nakhlites are different from those of Martian <span class="hlt">shergottites</span>, whose radiometric ages vary by nearly a factor of three (approx. 165-475 Myr) and whose space exposure ages vary over a factor of approx. 20. <span class="hlt">Shergottite</span> ages suggest that multiple locations on the Martian surface have been sampled, whereas nakhlite data imply sampling of only one Mars surface location. Because older Martian surfaces are expected to be more abundant, it seems surprising that all nakhlites would represent only one Martian impact event. To address this issue, we are measuring the (39)Ar-(40)Ar ages of Y-000593, NWA-998, Nakhla, and MIL-03346, and the space (CRE) exposure age of NWA998. Additional information is included in the original extended abstract.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_11 --> <div id="page_12" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="221"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015MsT..........1T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015MsT..........1T"><span id="translatedtitle">Hydrogen Isotopic Systematics of Nominally Anhydrous Phases in Martian Meteorites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tucker, Kera</p> <p></p> <p>Hydrogen isotope compositions of the martian atmosphere and crustal materials can provide unique insights into the hydrological and geological evolution of Mars. While the present-day deuterium-to-hydrogen ratio (D/H) of the Mars atmosphere is well constrained (~6 times that of terrestrial ocean water), that of its deep silicate interior (specifically, the mantle) is less so. In fact, the hydrogen isotope composition of the primordial martian mantle is of great interest since it has implications for the origin and abundance of water on that planet. Martian meteorites could provide key constraints in this regard, since they crystallized from melts originating from the martian mantle and contain phases that potentially record the evolution of the H 2O content and isotopic composition of the interior of the planet over time. Examined here are the hydrogen isotopic compositions of Nominally Anhydrous Phases (NAPs) in eight martian meteorites (five <span class="hlt">shergottites</span> and three nakhlites) using Secondary Ion Mass Spectrometry (SIMS). This study presents a total of 113 individual analyses of H2O contents and hydrogen isotopic compositions of NAPs in the <span class="hlt">shergottites</span> Zagami, Los Angeles, QUE 94201, SaU 005, and Tissint, and the nakhlites Nakhla, Lafayette, and <span class="hlt">Yamato</span> 000593. The hydrogen isotopic variation between and within meteorites may be due to one or more processes including: interaction with the martian atmosphere, magmatic degassing, subsolidus alteration (including shock), and/or terrestrial contamination. Taking into consideration the effects of these processes, the hydrogen isotope composition of the martian mantle may be similar to that of the Earth. Additionally, this study calculated upper limits on the H2O contents of the <span class="hlt">shergottite</span> and nakhlite parent melts based on the measured minimum H2O abundances in their maskelynites and pyroxenes, respectively. These calculations, along with some petrogenetic assumptions based on previous studies, were subsequently used</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150001940','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150001940"><span id="translatedtitle">Early Solar System Alkali Fractionation Events Recorded by K-Ca Isotopes in the <span class="hlt">Yamato</span>-74442 LL-Chondritic Breccia</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Tatsunori, T.; Misawa, K.; Okano, O.; Shih, C.-Y.; Nyquist, L. E.; Simon, J. I.; Tappa, M. J.; Yoneda, S.</p> <p>2015-01-01</p> <p>Radiogenic ingrowth of Ca-40 due to decay of K-40 occurred early in the solar system history causing the Ca-40 abundance to vary within different early-former reservoirs. Marshall and DePaolo ] demonstrated that the K-40/Ca-40 decay system could be a useful radiogenic tracer for studies of terrestrial rocks. Shih et al. [3,4] determined 40K/40Ca ages of lunar granitic rock fragments and discussed the chemical characteristics of their source materials. Recently, Yokoyama et al. [5] showed the application of the K-40/Ca-40 chronometer for high K/Ca materials in ordinary chondrites (OCs). High-precision calcium isotopic data are needed to constrain mixing processes among early solar system materials and the time of planetesimal formation. To better constrain the solar system calcium isotopic compositions among astromaterials, we have determined the calcium isotopic compositions of OCs and an angrite. We further estimated a source K/Ca ratio for alkali-rich fragments in a chondritic breccia using the estimated solar system initial Ca-40/Ca-44.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120013688','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120013688"><span id="translatedtitle">Martian Igneous Geochemistry: The Nature of the Martian Mantle</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mittlefehldt, D. W.; Elkins-Tanton, L. T.; Peng, Z. X.; Herrin, J. S.</p> <p>2012-01-01</p> <p>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 <span class="hlt">lherzolites</span> (<span class="hlt">shergottites</span>).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/936965','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/936965"><span id="translatedtitle">Uranium-lead isotope systematics of Mars inferred from the basaltic <span class="hlt">shergottite</span> QUE 94201</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gaffney, A M; Borg, L E; Connelly, J N</p> <p>2006-12-22</p> <p>Uranium-lead ratios (commonly represented as {sup 238}U/{sup 204}Pb = {mu}) calculated for the sources of martian basalts preserve a record of petrogenetic processes that operated during early planetary differentiation and formation of martian geochemical reservoirs. To better define the range of {mu} values represented by the source regions of martian basalts, we completed U-Pb elemental and isotopic analyses on whole rock, mineral and leachate fractions from the martian meteorite Queen Alexandra Range 94201 (QUE 94201). The whole rock and silicate mineral fractions have unradiogenic Pb isotopic compositions that define a narrow range ({sup 206}Pb/{sup 204}Pb = 11.16-11.61). In contrast, the Pb isotopic compositions of weak HCl leachates are more variable and radiogenic. The intersection of the QUE 94201 data array with terrestrial Pb in {sup 206}Pb/{sup 204}Pb-{sup 207}Pb/{sup 204}Pb-{sup 208}Pb/{sup 204}Pb compositional space is consistent with varying amounts of terrestrial contamination in these fractions. We calculate that only 1-7% contamination is present in the purified silicate mineral and whole rock fractions, whereas the HCl leachates contain up to 86% terrestrial contamination. Despite the contamination, we are able to use the U-Pb data to determine the initial {sup 206}Pb/{sup 204}Pb of QUE 94201 (11.086 {+-} 0.008) and calculate the {mu} value of the QUE 94201 mantle source to be 1.823 {+-} 0.008. This is the lowest {mu} value calculated for any martian basalt source, and, when compared to the highest values determined for martian basalt sources, indicates that {mu} values in martian source reservoirs vary by at least 100%. The range of source {mu} values further indicates that the {mu} value of bulk silicate Mars is approximately three. The amount of variation in the {mu} values of the mantle sources ({mu} {approx} 2-4) is greater than can be explained by igneous processes involving silicate phases alone. We suggest the possibility that a small amount of sulfide crystallization may generate large extents of U-Pb fractionation during formation of the mantle sources of martian basalts.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20060020745','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20060020745"><span id="translatedtitle">Ar-Ar Age of <span class="hlt">Shergottite</span> Dhofar 378: Formation or Early Shock Event?</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Park, J.; Bogard, Don D.</p> <p>2006-01-01</p> <p>The Ar-39-Ar40 data for 16 stepwise temperature extractions of mixed mesostasis plus plagioclase show the following major characteristics. Changes in the K/Ca ratio and in the differential rate of Ar-39 release with extraction temperature suggest three distinct, but overlapping Ar diffusion domains: <13%, 13-45%, and >45% cumulative Ar-39 release:. The youngest Ar-Ar age, approx.162-165 Myr is observed at approx.28-40% Ar-39 release, which we attribute primarily to the mesostasis. Extractions releasing >45% Ar-39, probably from plagioclase, suggest older Ar-Ar ages and indicate release of trapped martian Ar-40. An isochron plot for 8 extractions, releasing 3-45% of the Ar-39 and corrected for 36Arcos using directly measured 36Arcos, gives an Ar-Ar age of 143+/-4 Myr (where the +/- ignores the uncertainty in applying a correction for Ar-36cos). Applying a correction assuming only one-half of the measured Ar-36cos gives an age of 159+/-2 Myr. Correcting for cos-Ar-36 using the minimum measured Ar-36/Ar-37 ratio gives a minimum possible age of 138+/-5 Myr. All of these ages are within combined uncertainties of the Sm-Nd age of 157+/-24 Myr [4]. The trapped Ar-40/Ar-36 ratio obtained from the isochron is largely defined by the highest [K] data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1019058','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1019058"><span id="translatedtitle">Disturbance of isotope systematics in meteorites during shock and thermal metamorphism and implications for <span class="hlt">shergottite</span> chronology</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gaffney, A M; Borg, L E; Asmerom, Y</p> <p>2008-12-10</p> <p>Shock and thermal metamorphism of meteorites from differentiated bodies such as the Moon and Mars have the potential to disturb chronometric information contained in these meteorites. In order to understand the impact-related mechanisms and extent of disturbance to isochrons, we undertook experiments to shock and heat samples of 10017, a 3.6 billion year old lunar basalt. One sub-sample was shocked to 55 GPa, a second subsample was heated to 1000 C for one week, and a third sub-sample was maintained as a control sample. Of the isotope systems analyzed, the Sm-Nd system was the least disturbed by shock or heat, followed by the Rb-Sr system. Ages represented by the {sup 238}U-{sup 206}Pb isotope system were degraded by shock and destroyed with heating. In no case did either shock or heating alone result in rotated or reset isochrons that represent a spurious age. In some cases the true crystallization age of the sample was preserved, and in other cases age information was degraded or destroyed. Although our results show that neither shock nor thermal metamorphism alone can account for the discordant ages represented by different isotope systems in martian meteorites, we postulate that shock metamorphism may render a meteorite more susceptible than unshocked material to subsequent disturbance during impact-related heating or aqueous alteration on Mars or Earth. The combination of these processes may result in the disparate chronometric information preserved in some meteorites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19830067592&hterms=Peridotite&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DPeridotite','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19830067592&hterms=Peridotite&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DPeridotite"><span id="translatedtitle">Petrogenesis of the Elephant Moraine A79001 meteorite Multiple magma pulses on the <span class="hlt">shergottite</span> parent body</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mcsween, H. Y., Jr.; Jarosewich, E.</p> <p>1983-01-01</p> <p>The EETA 79001 achondrite consists of two distinct igneous lithologies joined along a planar, non-brecciated contact. Both are basaltic rocks composed primarily of pigeonite, augite, and maskelynite, but one contains zoned megacrysts of olivine, orthopyroxene, and chromite that represent disaggregated xenoliths of harzburzite. Both lithologies probably formed from successive volcanic flows or multiple injections of magma into a small, shallow chamber. Many similarities between the two virtually synchronous magmas suggest that they are related. Possible mechanisms to explain their differences involve varying degrees of assimilation, fractionation from similar parental magmas, or partial melting of a similar source peridotite; of these, assimilation of the observed megacryst assemblage seems most plausible. However, some isotopic contamination may be required in any of these petrogenetic models. The meteorite has suffered extensive shock metamorphism and localized melting during a large impact event that probably excavated and liberated it from its parent body.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150019423','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150019423"><span id="translatedtitle">Evidence from Hydrogen Isotopes in Meteorites for a Subsurface Hydrogen Reservoir on Mars</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Usui, Tomohiro; Alexander, Conel M. O'D.; Wang, Jianhua; Simon, Justin I.; Jones, John H.</p> <p>2015-01-01</p> <p>The surface geology and geomorphology of Mars indicates that it was once warm enough to maintain a large body of liquid water on its surface, though such a warm environment might have been transient. The transition to the present cold and dry Mars is closely linked to the history of surface water, yet the evolution of surficial water is poorly constrained. We have conducted in situ hydrogen isotope (D/H) analyses of quenched and impact glasses in three Martian meteorites (<span class="hlt">Yamato</span> 980459, EETA79001, LAR 06319) by Cameca ims-6f at Digital Terrain Models (DTM) following the methods of [1]. The hydrogen isotope analyses provide evidence for the existence of a distinct but ubiquitous water/ice reservoir (D/H = 2-3 times Earth's ocean water: Standard Mean Ocean Water (SMOW)) that lasted from at least the time when the meteorites crystallized (173-472 Ma) to the time they were ejected by impacts (0.7-3.3 Ma), but possibly much longer [2]. The origin of this reservoir appears to predate the current Martian atmospheric water (D/H equals approximately 5-6 times SMOW) and is unlikely to be a simple mixture of atmospheric and primordial water retained in the Martian mantle (D/H is approximately equal to SMOW [1]). Given the fact that this intermediate-D/H reservoir (2-3 times SMOW) is observed in a diverse range of Martian materials with different ages (e.g., SNC (<span class="hlt">Shergottites</span>, Nakhlites, Chassignites) meteorites, including <span class="hlt">shergottites</span> such as ALH 84001; and Curiosity surface data [3]), we conclude that this intermediate-D/H reservoir is likely a global surficial feature that has remained relatively intact over geologic time. We propose that this reservoir represents either hydrated crust and/or ground ice interbedded within sediments. Our results corroborate the hypothesis that a buried cryosphere accounts for a large part of the initial water budget of Mars.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015M%26PS...50.1703B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015M%26PS...50.1703B"><span id="translatedtitle">Influence of redox conditions on the intensity of Mars crustal magnetic anomalies</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brachfeld, Stefanie; Shah, Deepa; First, Emily; Hammer, Julia; Bowles, Julie</p> <p>2015-10-01</p> <p>We evaluate the relationship between the intensity of remanent magnetization and fO2 in natural and synthetic Mars meteorites. The olivine-phyric <span class="hlt">shergottite</span> meteorite <span class="hlt">Yamato</span> 980459 (Y-980459) and a sulfur-free synthetic analog (Y-98*) of identical major element composition were analyzed to explore the rock magnetic and remanence properties of a basalt crystallized from a primitive melt, and to explore the role of magmatic and alteration environment fO2 on Mars crustal anomalies. The reducing conditions under which Y-980459 is estimated to have formed (QFM-2.5; Shearer et al. 2006) were replicated during the synthesis of Y-98*. Y-980459 contains pyrrhotite and chromite. Chromite is the only magnetic phase in Y-98*. The remanence-carrying capacity of Y-980459 is comparable to other <span class="hlt">shergottites</span> that formed in the fO2 range of QFM-3 to QFM-1. The remanence-carrying capacity of these low fO2 basalts is 1-2 orders of magnitude too weak to account for the intense crustal anomalies observed in Mars's southern cratered highlands. Moderately oxidizing conditions of >QFM-1, which are more commonly observed in nakhlites and Noachian breccias, are key to generating either a primary igneous assemblage or secondary alteration assemblage capable of acquiring an intense remanent magnetization, regardless of the basalt character or thermal history. This suggests that if igneous rocks are responsible for the intensely magnetized crust, these oxidizing conditions must have existed in the magmatic plumbing systems of early Mars or must have existed in the crust during secondary processes that led to acquisition of a chemical remanent magnetization.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002EGSGA..27.3164D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002EGSGA..27.3164D"><span id="translatedtitle">Lead Abundance In The Martian Mantle Deduced From The Isotopic Data In Snc Meteorites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dreibus, G.; Jagoutz, E.</p> <p></p> <p>Isotopic data are a powerful tool for the study of planetary evolution. Assuming that the SNC meteorites are rocks from Mars their Sm-Nd-, Rb-Sr- and Pb-Pb-isotope systematics reveal the time scale for the chemical evolution of the Martian mantle. From the Rb -Sr isotopic systematic the existence of 3 isotopically distinct reservoirs on Mars was postulated, which remained isolated for a period of 4.3 +/- 0.2 Ga. The basaltic <span class="hlt">shergottites</span> Shergotty, Zagami and Los Angeles have relatively high radiogenic Sr, which might come from a planetary crust. A second group, characterized by non radiogenic Sr, consists of the two mafic cumulates Nakhla and Chassigny, the olivine rich basaltic <span class="hlt">shergottites</span> DaG 476, SaU 005, Dhofar 019and the basaltic <span class="hlt">shergottite</span> QUE 94201, which may represent the depleted mantle. The depletion of this reservoir must have taken place during a very early process. as derived from the primitive Sr isotopes and the existence of Nd-142, the daughter product of the extinct Sm-146, found in Chassigny, the Nakhlites, SaU 005, and DaG476. A third group, with intermediate Sr isotopic composition, represented by the <span class="hlt">lherzolitic</span> <span class="hlt">shergottites</span>, could be derived from a primitive, unfractionated mantle. Our observed correlation of Sr-isotopes with Pb-isotopes in SNC's permits to estimate the Pb abundance for the Martian mantle. The Pb isotopes of all measured SNCs show a similar pattern as Sr isotopes. The initial Pb data of Los Angeles, Shergotty, and Zagami from the enriched crustal reservoir and of Nakhla and SaU 005 from the depleted mantle reservoir plot close to the 4.5 Ga Pb -Pb isochron.. We used this correlation to estimate the µ value (238U/204Pb) of 3.1 for the Martian mantle. This corresponds to 366 ppb Pb. Compared to the Earth with a µ = 8.8, Pb is enriched on Mars by at least a fact or of 2.5. The same enrichment was found for all other moderately volatile and volatile elements on Mars. From the high abundance of Pb in the sulfide phases of iron</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20030111022&hterms=rim&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Drim','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20030111022&hterms=rim&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Drim"><span id="translatedtitle">Mineralogy and Textural Characteristics of Fine-grained Rims in the <span class="hlt">Yamato</span> 791198 CM2 Carbonaceous Chondrite: Constraints on the Location of Aqueous Alteration</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Chizmadia, Lysa J.; Brearley, Adrian J.</p> <p>2003-01-01</p> <p>Carbonaceous chondrites provide important clues into the nature of physical and chemical processes in the early solar system. A question of key importance concerns the role of water in solar nebular and asteroidal processes. The effects of water on primary mineral assemblages have been widely recognized in chondritic meteorites, especially the CI and CM carbonaceous chondrites. These meteorites have undergone extensive aqueous alteration that occurred prior to their arrival on Earth. In the case of the CM chondrites, this alteration has resulted in the partial to complete replacement of the primary nebular phases with secondary alteration phases. Considerable controversy exists as to the exact location where the alteration of the CM chondrites occurred. Several textural lines of evidence have been cited in support of aqueous alteration prior to the accretion of the final parent asteroid. An important line of evidence to support this hypothesis is the dis-equilibrium nature of fine-grained rims and matrix materials. [2] also noted the juxtaposition of micron-sized Fe-Ni metal grains and apparently unaltered chondrule glass against hydrated rim silicates. Conversely, there is a large body of evidence in favor of parent body alteration such as the occurrence of undisturbed Fe-rich aureoles and the systematic redistribution of elemental components over millimeters, e.g., Mg(+2) into the matrix and Fe(+2) into chondrules etc.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20010045186&hterms=rim&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Drim','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20010045186&hterms=rim&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Drim"><span id="translatedtitle">Petrographic Studies of Fine-grained Rims in the <span class="hlt">Yamato</span> 791198 cm Carbonaceous Chondrite and Comparison to Murchison and ALH81002</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Chizmadia, L. J.; Brearley, A. J.</p> <p>2001-01-01</p> <p>Fine-grained rims in Y791198 (CM2) have been studied in detail using SEM and EPMA techniques. In comparison with the more highly altered CM chondrite, ALH 81002, the rims are texturally and compositionally more heterogeneous. Additional information is contained in the original extended abstract.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19890049155&hterms=Dunite&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DDunite','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19890049155&hterms=Dunite&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DDunite"><span id="translatedtitle">Allan Hills 84025 - The second brachinite, far more differentiated than brachina, and an ultramafic achondritic clast from L chondrite <span class="hlt">Yamato</span> 75097</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Warren, P. H.; Kallemeyn, G. W.</p> <p>1989-01-01</p> <p>New bulk-compositional and petrographic data tend to confirm that dunitic-wehrlitic meteorite ALH84025 is a second brachinite. It is suggested here that ALH84025 originated as an olivine heteradcumulate, whereas Brachina, or ALH84025, originated as an olivine orthocumulate. The tendency for pyroxenes among brachinites to be high-Ca may be a consequence of a relatively low MgO/FeO ratio, and/or high Na/Ca and K/Ca ratios in the bulk parent body. New data for a 2.5-cm dunite-melatroctolite clast from L6 chondrite Y75097 are reported. This clast has experience depletion of middle REE, except for a large (+) Eu anomaly. The clast as a whole is enriched in phosphates, but almost exclusively in its least-metamorphosed 'core' portion, whereas the analyzed samples represent phosphate-poor portions. It is suggested that this bizarre assemblage probably originated as an achondrite containing cumulus olivine, plagioclase, and phosphate, not necessarily all from a single igneous source rock.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20100008620','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20100008620"><span id="translatedtitle">SM-ND Age and REE Systematics of Larkman Nunatek 06319: Closed System Fractional Crystallization of a <span class="hlt">Shergottite</span> Magma</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Shafer, J. T.; Brandon, A. D.; Lapen T. J.; Righter, M.; Peslier, A. H.</p> <p>2010-01-01</p> <p>Sm-Nd isotopic data were collected on mineral separates and bulk rock powders of LAR 06319, yielding an age of 180+/-13 Ma (2(sigma)). This age is concordant with the Lu-Hf age (197+/-29 Ma, [1]) determined in conjunction with these data and the Sm-Nd age (190+/-26 Ma) of Shih et al., 2009 [2]. The Sm-Nd data form at statistically significant isochron (Fig. 1) that is controlled largely by leachate-residue pairs (samples with the R suffix are residues after leaching in cold 2N HCl for 10 minutes).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19870038381&hterms=friedrich&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dfriedrich%252C%2Bh.','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19870038381&hterms=friedrich&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dfriedrich%252C%2Bh."><span id="translatedtitle">Shock-implanted noble gases - An experimental study with implications for the origin of Martian gases in <span class="hlt">shergottite</span> meteorites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bogard, Donald D.; Horz, Friedrich; Johnson, Pratt H.</p> <p>1986-01-01</p> <p>The shock-implantation of gases is studied by artificially shocking whole rock and power samples of terrestrial basalt to pressures of 2-40 GPa. Ar, Kr, Xe, and Ne were implanted into the silicate. It is observed that the amount of implanted gas is linearly proportional to its partial pressure over a pressure range of 0.0001 to 0.1 atmosphere. The fractionation effect in the implanted gas and the gas diffusion properties are examined. The amounts of gas that would have been implanted with 100 percent efficiency are calculated from the measured porosities of the power samples and are compared to observed abundances. It is determined that the implantation efficiencies are approximately 0.5 percent at 2 GPa, 7 percent at 5 GPa, and greater than 50 percent at both 20 and 35 GPa. The experimental data correlate with the shock implantation of Martian gases without mass fractionation into the shock-melted phase of meteorite EETA 79001.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20090011793','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20090011793"><span id="translatedtitle">Noble Gas Analysis for Mars Robotic Missions: Evaluating K-Ar Age Dating for Mars Rock Analogs and Martian <span class="hlt">Shergottites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Park, J.; Ming, D. W.; Garrison, D. H.; Jones, J. H.; Bogard, D. D.; Nagao, K.</p> <p>2009-01-01</p> <p>The purpose of this noble gas investigation was to evaluate the possibility of measuring noble gases in martian rocks and air by future robotic missions such as the Mars Science Laboratory (MSL). The MSL mission has, as part of its payload, the Sample Analysis at Mars (SAM) instrument, which consists of a pyrolysis oven integrated with a GCMS. The MSL SAM instrument has the capability to measure noble gas compositions of martian rocks and atmosphere. Here we suggest the possibility of K-Ar age dating based on noble gas release of martian rocks by conducting laboratory simulation experiments on terrestrial basalts and martian meteorites. We provide requirements for the SAM instrument to obtain adequate noble gas abundances and compositions within the current SAM instrumental operating conditions, especially, a power limit that prevents heating the furnace above approx.1100 C. In addition, Martian meteorite analyses from NASA-JSC will be used as ground truth to evaluate the feasibility of robotic experiments to constrain the ages of martian surface rocks.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008GeCoA..72.5819W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008GeCoA..72.5819W"><span id="translatedtitle">Isotopic and petrographic evidence for young Martian basalts</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Walton, Erin L.; Kelley, Simon P.; Herd, Christopher D. K.</p> <p>2008-12-01</p> <p>Radiometric age data for <span class="hlt">shergottites</span> yield ages of 4.0 Ga and 180-575 Ma; the interpretation of these ages has been, and remains, a subject of debate. Here, we present new 39Ar- 40Ar laser probe data on <span class="hlt">lherzolitic</span> <span class="hlt">shergottites</span> Allan Hills (ALH) 77005 and Northwest Africa (NWA) 1950. These two meteorites are genetically related, but display very different degrees of shock damage. On a plot of 40Ar/ 36Ar versus 39Ar/ 36Ar, the more strongly shocked ALH 77005 (45-55 GPa) does not yield an array of values indicating an isochron, but the data are highly scattered with the shock melts yielding 40Ar/ 36Ar ratios of 1600-2026. Apparent ages calculated from these extractions range from 374-8183 Ma, with 50% of the data, particularly from the shock melts, yielding impossibly old ages (>4.567 Ga). On the same plot, extractions from igneous minerals in the less shocked NWA 1950 (30-44 GPa) yield a fitted age of 382 ± 36 Ma. Argon extractions from the shock melts are well distinguished from minerals, with the melts exhibiting the highest 40Ar/ 36Ar ratios (1260-1488) and the oldest apparent ages. Laser step heating was also performed on maskelynite separates from NWA 1950 yielding ages of 1000 Ma at the lowest release temperatures, and ages of 360 and 362 Ma at higher temperature steps. Stepped heating data from previous studies have yielded ages of 500 and 700 Ma to 1.7 Ga for ALH 77005 maskelynite separates. If the ages obtained from igneous minerals represent undegassed argon from an ancient (4.0 Ga) rock, then the ages are expected to anticorrelate with the degree of shock heating. The data do not support this inference. Our data support young crystallization ages for minerals and Martian atmosphere as the origin of excess 40Ar in the shock melts. The shock features of <span class="hlt">shergottites</span> are also reviewed in the context of what is known of the geologic history of the Martian surface through remote observation. The oldest, most heavily cratered surfaces of Mars are thought to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080009609','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080009609"><span id="translatedtitle">Duration of a Magma Ocean and Subsequent Mantle Overturn in Mars: Evidence from Nakhlites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Debaille, V.; Brandon, A. D.; Yin, Q.-Z.; Jacobsen, B.</p> <p>2008-01-01</p> <p>It is now generally accepted that the heat produced by accretion, short-lived radioactive elements such as Al-26, and gravitational energy from core formation was sufficient to at least partially melt the silicate portions of terrestrial planets resulting in a global-scale magma ocean. More particularly, in Mars, the geochemical signatures displayed by <span class="hlt">shergottites</span>, are likely inherited from the crystallization of this magma ocean. Using the short-lived chronometer Sm-146 - Nd-142 (t(sup 1/2) = 103 Myr), the duration of the Martian magma ocean (MMO) has been evaluated to being less than 40 Myr, while recent and more precise ND-142/ND-144 data were used to evaluate the longevity of the MMO to approximately 100 Myr after the solar system formation. In addition, it has been proposed that the end of the crystallization of the MMO may have triggered a mantle overturn, as a result of a density gradient in the cumulate layers crystallized at different levels. Dating the mantle overturn could hence provide additional constraint on the duration of the MMO. Among SNC meteorites, nakhlites are characterized by high epsilon W-182 of approximately +3 and an epsilon Nd-142 similar to depleted <span class="hlt">shergottites</span> of +0.6-0.9. It has hence been proposed that the source of nakhlites was established very early in Mars history (approximately 8-10 Myr). However, the times recorded in HF-182-W-182 isotope system, i.e. when 182Hf became effectively extinct (approximately 50 Myr after solar system formation) are less than closure times recorded in the Sm-146-Nd-142 isotope system (with a full coverage of approximately 500 Myr after solar system formation). This could result in decoupling between the present-day measured epsilon W-182 and epsilon Nd-142 as the SM-146 may have recorded later differentiation events in epsilon ND-142 not observed in epsilon W-182 values. With these potential complexities in short-lived chronological data for SNC's in mind, new Hf-176/Hf-177, Nd-143/Nd-144 and Nd</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20050167788&hterms=PT&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DPT.','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20050167788&hterms=PT&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DPT."><span id="translatedtitle">Lunar and Planetary Science XXXVI, Part 4</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2005-01-01</p> <p>Contents include the following: High-Resolution Electron Energy-Loss Spectroscopy (HREELS) Using a Monochromated TEM/STEM. Dynamical Evolution of Planets in Open Clusters. Experimental Petrology of the Basaltic <span class="hlt">Shergottite</span> <span class="hlt">Yamato</span> 980459: Implications for the Thermal Structure of the Martian Mantle. Cryogenic Reflectance Spectroscopy of Highly Hydrated Sulfur-bearing Salts. Implications for Core Formation of the Earth from High Pressure-Temperature Au Partitioning Experiments. Uranium-Thorium Cosmochronology. Protracted Core Differentiation in Asteroids from 182Hf-182W Systematics in the Eagle Station Pallasite. Maximizing Mission Science Return Through Use of Spacecraft Autonomy: Active Volcanism and the Autonomous Sciencecraft Experiment. Classification of Volcanic Eruptions on Io and Earth Using Low-Resolution Remote Sensing Data. Isotopic Mass Fractionation Laws and the Initial Solar System (sup26)Al/(sup27)Al Ratio. Catastrophic Disruption of Porous and Solid Ice Bodies (sup187)Re-(sup187)Os Isotope Disturbance in LaPaz Mare Basalt Meteorites. Comparative Petrology and Geochemistry of the LaPaz Mare Basalt Meteorites. A Comparison of the Structure and Bonding of Carbon in Apex Chert Kerogenous Material and Fischer-Tropsch-Type Carbons. Broad Spectrum Characterization of Returned Samples: Orientation Constraints of Small Samples on X-Ray and Other Spectroscopies. Apollo 14 High-Ti Picritic Glass: Oxidation/Reduction by Condensation of Alkali Metals. New Lunar Meteorites from Oman: Dhofar 925, 960 and 961. The First Six Months of Iapetus Observations by the Cassini ISS Camera. First Imaging Results from the Iapetus B/C Flyby of the Cassini Spacecraft. Radiative Transfer Calculations for the Atmosphere of Mars in the 200-900 nm Range. Geomorphologic Map of the Atlantis Basin, Terra Sirenum, Mars. The Meaning of Iron 60: A Nearby Supernova Injected Short-lived Radionuclides into Our Protoplanetary Disk.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120012511','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120012511"><span id="translatedtitle">Nature of Reduced Carbon in Martian Meteorites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gibson, Everett K., Jr.; McKay, D. S.; Thomas-Keprta, K. L.; Clemett, S. J.; White, L. M.</p> <p>2012-01-01</p> <p>Martian meteorites provide important information on the nature of reduced carbon components present on Mars throughout its history. The first in situ analyses for carbon on the surface of Mars by the Viking landers yielded disappointing results. With the recognition of Martian meteorites on Earth, investigations have shown carbon-bearing phases exist on Mars. Studies have yielded presence of reduced carbon, carbonates and inferred graphitic carbon phases. Samples ranging in age from the first approximately 4 Ga of Mars history [e.g. ALH84001] to nakhlites with a crystallization age of 1.3 Ga [e.g. Nakhla] with aqueous alteration processes occurring 0.5-0.7 Ga after crystallizaton. <span class="hlt">Shergottites</span> demonstrate formation ages around 165-500 Ma with younger aqueous alterations events. Only a limited number of the Martian meteorites do not show evidence of significance terrestrial alterations. Selected areas within ALH84001, Nakhla, <span class="hlt">Yamato</span> 000593 and possibly Tissint are suitable for study of their indigenous reduced carbon bearing phases. Nakhla possesses discrete, well-defined carbonaceous phases present within iddingsite alteration zones. Based upon both isotopic measurements and analysis of Nakhla's organic phases the presence of pre-terrestrial organics is now recognized. The reduced carbon-bearing phases appear to have been deposited during preterrestrial aqueous alteration events that produced clays. In addition, the microcrystalline layers of Nakhla's iddingsite have discrete units of salt crystals suggestive of evaporation processes. While we can only speculate on the origin of these unique carbonaceous structures, we note that the significance of such observations is that it may allow us to understand the role of Martian carbon as seen in the Martian meteorites with obvious implications for astrobiology and the pre-biotic evolution of Mars. In any case, our observations strongly suggest that reduced organic carbon exists as micrometer- size, discrete structures</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_12 --> <div id="page_13" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="241"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMMR23B2362D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMMR23B2362D"><span id="translatedtitle">New Bulk Sulfur Measurements of Martian Meteorites - Implications for Sulfur Cycle on Mars</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ding, S.; Dasgupta, R.; Lee, C.; Wadhwa, M.</p> <p>2013-12-01</p> <p>Magmatic degassing was likely critical in giving rise to a thick atmosphere of ancient Mars and SO2 and H2S could have been key greenhouse gases. How much S was released depends on (1) the S content of the mantle-derived magma and (2) the magmatic sulfur budget of the basaltic crust. While the former is estimated by S content of basaltic melts at sulfide saturation (SCSS) [1,2], assuming mantle-derived magma is sulfide saturated, it is unclear how much S gets trapped during crystallization of basalts in the crust versus how much is released to the atmosphere. S content of the martian crust can be estimated from martian meteorites, yet bulk S concentration data of martian meteorites is limited [3]. Further, most martian meteorites contain cumulus minerals and some have experienced secondary alteration (weathering/ impact effects), which could either deplete or enrich S in these samples. To better constrain the degassing of S from the martian interior, we measured bulk S contents of 7 martian meteorites via high mass-resolution solution ICP-MS [4]. Basaltic <span class="hlt">shergottites</span> Los Angeles, Zagami and NWA 856 have S contents of 2865×224, 1954×91 and 1584×10 ppm, respectively while clinopyroxenites Nakhla and NWA 998 give values of 690×60 and 253×42 ppm S. Olivine-phyric <span class="hlt">shergottites</span> NWA 1068 and Tissint have intermediate S contents of 1280×48 and 2120×68 ppm. The meteorites have lower S contents than the predicted SCSS of ~3500-4500 ppm [2] along liquid line of descent for a liquid similar to <span class="hlt">Yamato</span> 980459 at 1 GPa, estimated using alphaMELTS. Taking into account the possible proportion of inter-cumulus liquid (f= 6-70 wt.%) in the analyzed meteorites estimated by previous studies, the degassed S could be as low as ~300-1900 ppm (estimated by the difference between the SCSS×f and the S in the meteorites). However, nakhlite Nakhla and basaltic <span class="hlt">shergottites</span> NWA 856 and Zagami show higher S than the calculated SCSS×f. In these two meteorites, sulfides occur as</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20040059920&hterms=Stone+Age&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3D%2528Stone%2BAge%2529','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20040059920&hterms=Stone+Age&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3D%2528Stone%2BAge%2529"><span id="translatedtitle">Rb-Sr and Sm-Nd Isotope Systematics of <span class="hlt">Shergottite</span> NWA 856: Crystallization Age and Implications for Alteration of Hot Desert SNC Meteorites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Brandon, A. D.; Nyquist, L. E.; Shih, C.-Y.; Wiesmann, H.</p> <p>2004-01-01</p> <p>Nakhlite NWA 998 was discovered in Algeria in 2001, and is unique among the six known members of this group of Martian meteorites in containing significant modal orthopyroxene. Initial petrologic and isotopic data were reported by Irving et al. This 456 gram stone consists mainly of sub-calcic augite with subordinate olivine and minor orthopyroxene, titanomagnetite, pyrrhotite, chlorapatite, and intercumulus An(sub 35) plagioclase. We report here preliminary results of radiogenic isotopic analyses conducted on fragmental material from the main mass.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080030951','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080030951"><span id="translatedtitle">Oxygen Fugacity of the Upper Mantle of Mars. Evidence from the Partitioning Behavior of Vanadium in Y980459 (Y98) and other Olivine-Phyric <span class="hlt">Shergottites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Shearer, C. K.; McKay, G. A.; Papike, J. J.; Karner, J.</p> <p>2006-01-01</p> <p>Using partitioning behavior of V between olivine and basaltic liquid precisely calibrated for martian basalts, we determined the redox state of primitive (olivine-rich, high Mg#) martian basalts near their liquidus. The combination of oxidation state and incompatible element characteristics determined from early olivine indicates that correlations between fO2 and other geochemical characteristics observed in many martian basalts is also a fundamental characteristic of these primitive magmas. However, our data does not exhibit the range of fO2 observed in these previous studies.. We conclude that the fO2 for the martian upper mantle is approximately IW+1 and is incompatible-element depleted. It seems most likely (although clearly open to interpretation) that these mantle-derived magmas assimilated a more oxidizing (>IW+3), incompatible-element enriched, lower crustal component as they ponded at the base of the martian crust.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19990063444&hterms=geochemistry&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dgeochemistry','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19990063444&hterms=geochemistry&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dgeochemistry"><span id="translatedtitle">Petrology and Geochemistry of a Mg- and Al-Rich Orthopyroxenite Xenolith in the EETA79001 <span class="hlt">Shergottite</span>: Implications for Mars Crustal Evolution</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Berkley, John L.</p> <p>1999-01-01</p> <p>EETA79001 is a Mars meteorite (SNC) consisting of multiple rock types, including two basalt types, olivine and pyroxene xenocrysts, and ultramafic xenoliths. This study is focused on the petrology and geochemistry of one orthopyroxenite xenolith in PTS 68, designated X-1. It consists of chemically homogeneous orthopyroxene cores with exceptionally high Mg/Fe (mg#=85) and Al. Cores are permeated by minute high-Si+Al glassy inclusions, some with augite microlites. Magnesian core areas are mantled by more Fe-rich orthopyroxene rims grading to pigeonite away from cores. The xenolith is transected by cross-cutting shear planes, some of pre-incorporation origin. Major and minor element composition and variation suggest that core areas are primarily igneous, crystallized from a high temperature mafic melt. However, nearly constant mg# across cores suggest metamorphic equilibration. Si+Al inclusions may result from, among other processes, exsolution of feldspathic material during subsolidus cooling, or may be solid materials (alkali feldspar) poikilitically enclosed by growing igneous orthopyroxene crystals. Late reaction with more fractionated melts produced Fe-rich mantles, the whole assemblage later cut by tectonic micro-shear planes. Raw electron microprobe data produced during this study are available on request from the author.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993GeCoA..57..907K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993GeCoA..57..907K"><span id="translatedtitle">Examination of organic compounds from insoluble organic matter isolated from some Antarctic carbonaceous chondrites by heating experiments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Komiya, M.; Shimoyama, A.; Harada, K.</p> <p>1993-02-01</p> <p>Insoluble organic matter isolated from five Antarctic CM2 chondrites was heated in a thermal analyzer from room temperature to 800 C under helium atmosphere. Organic compounds from the thermal decomposition of the <span class="hlt">Yamato</span>-791198 sample were studied by a gas chromatograph-mass spectrometer (GC-MS). The number of compounds identified was over 120, belonging mainly to the two following groups: (1) benzene and naphthalene, and their alkyl derivatives; and (2) sulfur-containing heterocycles and their alkyl derivatives. Small amounts of aliphatic hydrocarbons and nitriles were also detected. Relative amounts of compounds released from the five chondrite samples were monitored by the MS with increasing temperature. <span class="hlt">Yamato</span>-74662 and <span class="hlt">Yamato</span>-791198 showed organic compounds mainly over the temperature range of 300-600 C, while the other three (<span class="hlt">Yamato</span>-793321, <span class="hlt">Yamato</span>-86720, and Belgica-7904) did not show any, except small amounts of benzene. These results indicate that the insoluble organics in <span class="hlt">Yamato</span>-74662 and <span class="hlt">Yamato</span>-791198 possess a thermally labile organic fraction, whereas those in <span class="hlt">Yamato</span>-793321, <span class="hlt">Yamato</span>-86720, and Belgica-7904 do not and are graphitic. The difference between the insoluble organic fractions may be related to aqueous alteration and thermal metamorphism on the parent bodies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMMR11C2507D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMMR11C2507D"><span id="translatedtitle">Sulfur Concentration of Martian Magmas at Sulfide Saturation at High Pressures and Temperatures - Implications for Martian Magma Ocean and Magmatic Differentiation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ding, S.; Dasgupta, R.</p> <p>2012-12-01</p> <p>Sulfur is critical for a wide range of processes of terrestrial planets including thermal evolution of core and atmosphere and geochemistry of mantle and crust. For Mars, sulfur is particularly important because it may be abundant in the core [1] while SO 2 and H2 S might have exerted a strong greenhouse climate in the past [2]. A critical parameter that affects sulfur distribution during differentiation is the sulfur carrying capacity of mantle melts. However, most experiments constraining sulfur content at sulfide saturation (SCSS) are conducted on FeO poor (~5-12 wt.%) basalts [3] and recent experiments on high-FeO (~16-22 wt.%, [4]) Martian basalts are restricted to ≤0.8 GPa [5]. To constrain SCSS of Martian magmas at mantle conditions, we simulated basalt-sulfide melt equilibria (S added as 15-30 wt.% FeS) in Gr capsules using a piston cylinder at 1-3 GPa and 1500-1700 °C. Two starting compositions, equivalent to olivine-phyric <span class="hlt">shergottites</span> <span class="hlt">Yamato</span>980459 (Y98; ~17.53 wt.% FeO) and NWA 2990 (NWA; ~16.42 wt.% FeO) and thought to be primary magma [6] were used. A composition Y98+1.4 wt.% H2O was also explored to constrain the effect of water on SCSS. All experiments produced quenched sulfide and silicate melts ± opx . FeS species in the NWA glasses was confirmed from peaks at 300-400 cm-1 in Raman spectra [7]. At 1600 °C, SCSS, measured using EPMA, decreases with pressure, 4800 to 3500 ppm from 1 to 2.5 GPa for Y98, ~5440 to 4380 ppm from 1 to 2 GPa for Y98+1.4 wt.% H2O, and 5000 to 3000 ppm from 1 to 3 GPa for NWA. At 2 GPa, SCSS of NWA increases with temperature, 3300 to 4600 ppm from 1500 to 1700 °C. Combining new and previous experiments on Martian basalts [5] (a total of 28 SCSS data with FeO* of 9.3-32.78 wt.%), a preliminary equation of the form LnS (ppm) = a + b.P + c/T +d.XSiO2 + e.XAl2O3 + f.LnXFeO was fitted, where P is in GPa, T in K, and X represents mole fraction of a given oxide. Our study suggests that at conditions of final melt</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014LPICo1819.1004S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014LPICo1819.1004S"><span id="translatedtitle">The Chlorine Isotope Composition of Martian Meteorites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sharp, Z. D.; Shearer, C. K.; Agee, C.; Burger, P. V.; McKeegan, K. D.</p> <p>2014-11-01</p> <p>The Cl isotope composition of martian meteorites range from -3.8 to +8.6 per mil. Ol-phyric <span class="hlt">shergottites</span> are lightest; crustally contaminated samples are heaviest, basaltic <span class="hlt">shergottites</span> are in-between. The system is explained as two component mixing.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20130011110','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20130011110"><span id="translatedtitle">The Effects of Oxygen Fugacity on the Crystallization Sequence and Cr Partitioning of an Analog Y-98 Liquid</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bell, A. S.; Burger, P. V.; Le, Loan; Papike, J. J.; Jones, J.; Shearer, C. K.</p> <p>2013-01-01</p> <p>Interpreting the relationship between "enriched" olivine-phyric <span class="hlt">shergottites</span> (e.g. NWA 1068/1110) and the "enriched" pyroxene-plagioclase <span class="hlt">shergottites</span> (e.g. Shergotty, Los Angeles) is problematic. Symes et al. [1] and Shearer et al. [2]) proposed that the basaltic magma that crystallized to produce olivine-phyric <span class="hlt">shergottite</span> NWA 1068/1110 could produce pyroxene-plagioclase <span class="hlt">shergottites</span> with additional fractional crystallization. However, additional observations indicate that the relationship among the enriched <span class="hlt">shergottites</span> may be more complex [1-3]. For example, Herd [3] concluded that some portion of the olivine megacrysts in this meteorite was xenocrystic in origin, seemingly derived from more reduced basaltic liquids. This conclusion may imply that a variety of complex processes such as magma mixing, entrainment, and assimilation may play important roles in the petrologic history of these meteorites. It is therefore possible that these processes have obscured the petrogenetic linkages between the enriched olivine-phyric <span class="hlt">shergottites</span> and the pyroxene-plagioclase <span class="hlt">shergottites</span>. As a first order step in attempting to unravel these petrologic complexities, this study focuses upon exploring the effect of fO2 on the crystallization history for an analog primitive <span class="hlt">shergottite</span> liquid composition (Y98). Results from this work will provide a basis for reconstructing the record of fO2 in <span class="hlt">shergottites</span>, its effect on both mineral chemistries and valence state partitioning, and a means for examining the role of crystallization on the petrologic linkages between olivine-phyric and pyroxene-plagioclase <span class="hlt">shergottites</span>. A companion abstract [4] explores the behavior of V over this range of fO2.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010PolSc...4..215S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010PolSc...4..215S"><span id="translatedtitle">Bacterial communities in two Antarctic ice cores analyzed by 16S rRNA gene sequencing analysis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Segawa, Takahiro; Ushida, Kazunari; Narita, Hideki; Kanda, Hiroshi; Kohshima, Shiro</p> <p>2010-08-01</p> <p>Antarctic ice cores could preserve ancient airborne microorganisms. We examined bacteria in two Antarctic ice core samples, an interglacial age sample from Mizuho Base and a glacial age sample from the <span class="hlt">Yamato</span> Mountains, by 16S rRNA gene sequencing analysis. Bacterial density, the number of bacterial OTUs and Simpson’s diversity index was larger in the Mizuho sample than in the <span class="hlt">Yamato</span> sample. The 16S rDNA clone library from the Mizuho sample was dominated by the phylum Firmicutes, while the large part of that from the <span class="hlt">Yamato</span> sample was composed of the Gamma proteobacteria group. Major sources of these identified bacteria estimated from their database records also differed between the samples: in the Mizuho sample bacterial species recorded from animals were higher than that of the <span class="hlt">Yamato</span> sample, while in the <span class="hlt">Yamato</span> sample bacteria from aquatic and snow-ice environments were higher than that of the Mizuho sample. The results suggest that these bacteria were past airborne bacteria that would vary in density, diversity and species composition depending on global environmental change. Our results imply that bacteria in Antarctic ice cores could be used as new environmental markers for past environmental studies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19800036000&hterms=ice+age&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dice%2Bage','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19800036000&hterms=ice+age&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dice%2Bage"><span id="translatedtitle">Measurements of Cl-36 in Antarctic meteorites and Antarctic ice using a Van de Graaff accelerator</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nishiizumi, K.; Arnold, J. R.; Finkel, R. C.; Elmore, D.; Ferraro, R. D.; Gove, H. E.; Beukens, R. P.; Chang, K. H.; Kilius, L. R.</p> <p>1979-01-01</p> <p>The paper presents measurements of cosmic-ray produced (Cl-36) in Antarctic meteorites and ice using a Van de Graaff accelerator as an ultrasensitive mass spectrometer. Results from this ion counting technique are used to support a two-stage irradiation model for the <span class="hlt">Yamato</span>-7301 and Allan Hills-76008 meteorites and to show a long terrestrial age for Allan Hills-77002. <span class="hlt">Yamato</span>-7304 has a terrestrial age of less than 0.1 m.y., and the (Cl-36) content of the Antarctic ice sample from the <span class="hlt">Yamato</span> mountain is consistent with levels expected in currently depositing snow implying that the age of the ice cap at this site is less than on (Cl-36) half-life.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008M%26PS...43.1241S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008M%26PS...43.1241S"><span id="translatedtitle">Petrogenetic linkages among Martian basalts: Implications based on trace element chemistry of olivine</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shearer, C. K.; Burger, P. V.; Papike, J. J.; Borg, L. E.; Irving, A. J.; Herd, C.</p> <p>2008-10-01</p> <p>The <span class="hlt">shergottites</span> exhibit a range of major and trace element compositions, crystallization ages, and initial Sr, Nd, Hf, and Pb isotopic compositions. To constrain the physical mechanisms by which <span class="hlt">shergottites</span> obtain their compositional characteristics, we examined the major and trace element record preserved in olivine in the more primitive <span class="hlt">shergottites</span>. Based on such characteristics as the Mg#, V zoning, calculated DNi,Co, the olivine in Y-980459 are most likely phenocrysts. Many of these same characteristics indicate that the olivines in other <span class="hlt">shergottites</span> are not in equilibrium with the adjacent melt. However, in most cases they are not xenocrystic, but additions of olivine from the same basaltic system. Elephant Moraine (EET) A79001 may be an exception with the olivine data suggesting that it is xenocrystic. In this case, the olivine crystallized from a reduced and LREEdepleted melt and was incorporated into an oxidized and enriched basalt. Vanadium and CaO in olivine appear to record the appearance of spinel and pyroxene on the liquidus of most of the <span class="hlt">shergottites</span>. Most of the olivine <span class="hlt">shergottites</span> represent basalts produced by melting of reduced (IW to IW + 1), depleted mantle sources. Olivine data indicate that many of the primary melts derived from this source had similar Ni, Co, and Mn. <span class="hlt">Shergottites</span> such as Northwest Africa (NWA) 1110/1068 and perhaps Roberts Massif (RBT) 04261 that appear to be derived from more enriched sources have distinctly different olivine. In the case of NWA 1110/1068, the olivine data suggests that the enriched component was added to system prior to olivine crystallization.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20090032652','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20090032652"><span id="translatedtitle">Controls on Highly Siderophile Element Concentrations in Martian Basalt: Sulfide Saturation and Under-Saturation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Righter, Kevin</p> <p>2009-01-01</p> <p>Highly siderophile elements (HSE; Re, Au and the platinum group elements) in <span class="hlt">shergottites</span> exhibit a wide range from very high, similar to the terrestrial mantle, to very low, similar to sulfide saturated mid ocean ridge basalt (e.g., [1]). This large range has been difficult to explain without good constraints on sulfide saturation or under-saturation [2]. A new model for prediction of sulfide saturation places new constraints on this problem [3]. <span class="hlt">Shergottite</span> data: For primitive <span class="hlt">shergottites</span>, pressure and temperature estimates are between 1.2-1.5 GPa, and 1350-1470 C [4]. The range of oxygen fugacities is from FMQ-2 to IW, where the amount of Fe2O3 is low and thus does not have a significant effect on the S saturation values. Finally, the bulk compositions of <span class="hlt">shergottites</span> have been reported in many recent studies (e.g., [5]). All of this information will be used to test whether <span class="hlt">shergottites</span> are sulfide saturated [3]. Modeling values and results: The database for HSE partition coefficients has been growing with many new data for silicates and oxides [6-8] to complement a large sulfide database [9- 11]. Combining these data with simple batch melting models allows HSE contents of mantle melts to be estimated for sulfide-bearing vs. sulfide-free mantle. Combining such models with fractional crystallization modeling (e.g., [12]) allows HSE contents of more evolved liquids to be modeled. Most primitive <span class="hlt">shergottites</span> have high HSE contents (and low S contents) that can be explained by sulfide under-saturated melting of the mantle. An exception is Dhofar 019 which has high S contents and very low HSE contents suggesting sulfide saturation. Most evolved basaltic <span class="hlt">shergottites</span> have lower S contents than saturation, and intermediate HSE contents that can be explained by olivine, pyroxene, and chromite fractionation. An exception is EET A79001 lithology B, which has very low HSE contents and S contents higher than sulfide saturation values . evidence for sulfide saturation</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20070003723','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20070003723"><span id="translatedtitle">Rb-Sr and Sm-Nd Isotopic Studies of Martian Depleted Shergottes SaU 094/005</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Shih, C.-Y.; Nyquist, L. E.; Reese, Y.</p> <p>2007-01-01</p> <p>Sayh al Uhaymir (SaU) 094 and SaU 005 are olivine-phyric <span class="hlt">shergottites</span> from the Oman desert and are considered as pairs. [e.g., 1]. They are very similar to the Libyan desert <span class="hlt">shergottite</span> Dar al Gani (DaG) 476 in petrology, chemistry and ejection age [2-6]. This group of <span class="hlt">shergottites</span>, also recognized as depleted <span class="hlt">shergottites</span> [e.g. 7] has been strongly shocked and contains very low abundances of light rare earth elements (REE). In addition, terrestrial contaminants are commonly present in meteorites found in desert environments. Age-dating these samples is very challenging, but lower calcite contents in the SaU meteorites suggest that they have been subjected to less severe desert weathering than their DaG counterparts [3-4]. In this report, we present Rb-Sr and Sm-Nd isotopic results for SaU 094 and SaU 005, discuss the correlation of their ages with those of other similar <span class="hlt">shergottites</span>, and discuss their petrogenesis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19940016419&hterms=LL&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DLL','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19940016419&hterms=LL&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DLL"><span id="translatedtitle">Regolith breccia consisting of H and LL chondrite mixture</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Yanai, Keizo; Kojima, Hideyasu</p> <p>1993-01-01</p> <p>Antarctic meteorite <span class="hlt">Yamato</span>-8424 (Y-8424) is a regolith breccia that is homogenized mixture of H and LL chondrite components. The breccia consists mainly of a fine-grained material with mineral fragments of olivine, pyroxene, and Fe-Ni metal with traces of plagioclase.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19860019361','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19860019361"><span id="translatedtitle">Over 5,600 Japanese collection of Antarctic meteorites: Recoveries, curation and distribution</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Yanai, K.; Kojima, H.</p> <p>1986-01-01</p> <p>The history of recovery of meteorite fragments in the <span class="hlt">Yamato</span> Mountains, Allan Hills, and Victoria Land, Antarctica is reviewed. The Japanese collection of Antarctic meteorites were numbered, weighed, photographed, identified, and classified. Sample distribution of the Japanese Antarctic meteorites is described.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/15303347','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/15303347"><span id="translatedtitle">Genetic structure of a Japanese allotetraploid loach of the genus Cobitis (Osteichthyes, Cobitidae).</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kitagawa, Tadao; Yoshioka, Motoi; Kashiwagi, Masaaki; Okazaki, Toshio</p> <p>2003-01-01</p> <p>The Japanese allotetraploid spined loach of the genus Cobitis "<span class="hlt">yamato</span> complex" sensu SAITOH et al. (2000), distributed in Western Japan, originated from hybridization between C. biwae on the maternal side and C. striata (Kyushu form) on the paternal side. Mitochondrial (mt) and nuclear DNA were analyzed in order to determine the genetic relationships among 15 populations spanning the entire range of the <span class="hlt">yamato</span> complex. PCR-RFLP analysis of the ND1 mtDNA gene indicated that the <span class="hlt">yamato</span> complex contains two divergent types of mtDNA: type A, consisting of one haplotype observed only in the Fukagawa River and type B consisting of 12 haplotypes found in the entire area. Phylogenetic analysis based on the cytochrome b mtDNA gene corroborated RFLP analysis, and indicated that type A was closely related to a different species, C. biwae (Kochi group) and C. striata (large race), rather than type B. The results of RAPD analysis on the Fukagawa River individuals, where types A and B sympatrically existed suggested that no reproductive isolation occurs between them. The existence of two distinct mtDNA types within the <span class="hlt">yamato</span> complex suggest either multiple maternal origin at the speciation (tetraploidization) time or mtDNA introgression from other species afterwards. PMID:15303347</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19840009021','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19840009021"><span id="translatedtitle">Radioactivities in returned lunar materials and in meteorites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Fireman, E. L.</p> <p>1984-01-01</p> <p>Carbon 14 terrestial ages were determined with low level minicomputers and accelerator mass spectrometry on 1 <span class="hlt">Yamato</span> and 18 Allan Hills and nearby sited meteorites. Techniques for an accelerator mass spectrometer which make C(14) measurements on small samples were developed. Also Be(10) concentrations were measured in Byrd core and Allan Hills ice samples.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://files.eric.ed.gov/fulltext/ED401419.pdf','ERIC'); return false;" href="http://files.eric.ed.gov/fulltext/ED401419.pdf"><span id="translatedtitle">Adult Education for a Multiethnic Community: Japan's Challenge.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Sasagawa, Koichi</p> <p></p> <p>Modern education in Japan from 1868 to 1945 stressed "national education" in order to promote a sense of belonging to the Japanese state. The Japanese culture was thought to be superior to that of its "less advanced" East Asian neighbors, and Japanese people were encouraged to adopt a "<span class="hlt">Yamato</span>" identity (the seat of an ancient Japanese kingdom).…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/24872069','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24872069"><span id="translatedtitle">Revision of the genus Apophua Morley, 1913, from Japan (Hymenoptera, Ichneumonidae, Banchinae).</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Watanabe, Kyohei; Maeto, Kaoru</p> <p>2014-01-01</p> <p>Japanese species of the genus Apophua Morley, 1913, are revised. Eleven species are found from Japan and two of them, A. elegans sp. nov. and A. <span class="hlt">yamato</span> sp. nov., are newly described. Distribution data and an updated key to Japanese species are provided. PMID:24872069</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19980019921','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980019921"><span id="translatedtitle">Lunar Meteorite Queen Alexandra Range 93069 and the Iron Concentration of the Lunar Highlands Surface</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Korotev, Randy L.; Jolliff, Bradley L.; Rockow, Kaylynn M.</p> <p>1996-01-01</p> <p>Lunar meteorite Queen Alexandra Range 93069 is a clast-rich, glassy-matrix regolith breccia of ferroan, highly aluminous bulk composition. It is similar in composition to other feldspathic lunar meteorites but differs in having higher concentrations of siderophile elements and incompatible trace elements. Based on electron microprobe analyses of the fusion crust, glassy matrix, and clasts, and instrumental neutron activation analysis of breccia fragments, QUE 93069 is dominated by nonmare components of ferroan, noritic- anorthosite bulk composition. Thin section QUE 93069,31 also contains a large, impact-melted, partially devitrified clast of magnesian, anorthositic-norite composition. The enrichment in Fe, Sc, and Cr and lower Mg/Fe ratio of lunar meteorites <span class="hlt">Yamato</span> 791197 and <span class="hlt">Yamato</span> 82192/3 compared to other feldspathic lunar meteorites can be attributed to a small proportion (5-10%) of low-Ti mare basalt. It is likely that the non- mare components of <span class="hlt">Yamato</span> 82192/3 are similar to and occur in similar abundance to those of <span class="hlt">Yamato</span> 86032, with which it is paired. There is a significant difference between the average FeO concentration of the lunar highlands surface as inferred from the feldspathic lunar meteorites (mean: approx. 5.0%; range: 4.3-6.1 %) and a recent estimate based on data from the Clementine mission (3.6%).</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_13 --> <div id="page_14" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="261"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20040056053&hterms=magmatism&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dmagmatism','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20040056053&hterms=magmatism&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dmagmatism"><span id="translatedtitle">The Edge of Wetness: The Case for Dry Magmatism on Mars</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Jones, J. H.</p> <p>2004-01-01</p> <p>The issue of whether martian magmas are wet or dry is an important one. The answer to this basic question has profound consequences for how we think about Mars as a planet. Recently, several lines of evidence have been presented that collectively suggest that <span class="hlt">shergottite</span> parent magmas were once wet. These include: (i) phase equilibria studies that indicate that the Shergotty parent magma required 2 wt.% water in order to be co-saturated with both pigeonite and augite, (ii) reverse zoning of light lithophile elements (Li and B) in <span class="hlt">shergottite</span> pyroxenes, suggesting the exsolution and removal of an aqueous fluid, and (iii) measurement of D/H ratios in SNC minerals that are much lower than atmospheric, suggesting that there may be juvenile (primordial) mantle water. Below I will review the evidence for the diametrically opposite case, that <span class="hlt">shergottite</span> magmas were effectively dry (<< 1 wt.% H2O).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19790049197&hterms=Peridotite&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DPeridotite','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19790049197&hterms=Peridotite&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DPeridotite"><span id="translatedtitle">A petrogenetic model of the relationships among achondritic meteorites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Stolper, E.; Hays, J. F.; Mcsween, H. Y., Jr.</p> <p>1979-01-01</p> <p>Petrological evidence is used to support the hypothesis that although the magma source regions and parent bodies of basaltic achondrite, <span class="hlt">shergottite</span>, nakhlite, and chassignite meteorites are clearly distinct, they may be simply related. It is proposed that the peridotites which on partial melting generated the parent magmas of the <span class="hlt">shergottite</span> meteorites differed from those which gave rise to eucritic magmas by being enriched in a component rich in alkalis and other volatiles. Similarly, the source regions of the parent magmas of the nakhlite and chassignite meteorites differed from those on the <span class="hlt">shergottite</span> parent body by being still richer in this volatile-rich component. These regions could have been related by processes such as mixture of variable amounts of volatile-rich and volatile-poor components in planetary or nebular settings, or alternatively by variable varying degrees of volatile loss from volatile-rich materials.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19800035999&hterms=Peridotite&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DPeridotite','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19800035999&hterms=Peridotite&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DPeridotite"><span id="translatedtitle">Petrogenetic relationship between Allan Hills 77005 and other achondrites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mcsween, H. Y., Jr.; Taylor, L. A.; Stolper, E. M.; Muntean, R. A.; Okelley, G. D.; Eldridge, J. S.; Biswas, S.; Ngo, H. T.; Lipschutz, M. E.</p> <p>1979-01-01</p> <p>The paper presents chemical and petrologic data relating the Allan Hills (ALHA) 77005 achondrite from Antarctica and explores their petrogenetic relationship with the <span class="hlt">shergottites</span>. Petrologic similarities with the latter in terms of mineralogy, oxidation state, inferred source region composition, and shock ages suggest a genetic relationship, also indicated by volatile to involatile element ratios and abundances of other trace elements. ALHA 77005 may be a cumulate crystallized from a liquid parental to materials from which the <span class="hlt">shergottites</span> crystallized or a sample of peridotite from which <span class="hlt">shergottite</span> parent liquids were derived. Chemical similarities with terrestrial ultramafic rocks suggest that it provides an additional sample of the only other solar system body with basalt source origins chemically similar to the upper earth mantle.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150003794','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150003794"><span id="translatedtitle">New Martian Meteorite Is One of the Most Oxidized Found to Date</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hui, Hejiu; Peslier, Anne; Lapen, Thomas J.; Shafer, John T.; Brandon, Alan D.; Irving, Anthony J.</p> <p>2014-01-01</p> <p>As of 2013, about 60 meteorites from the planet Mars have been found and are being studied. Each time a new Martian meteorite is found, a wealth of new information comes forward about the red planet. The most abundant type of Martian meteorite is a <span class="hlt">shergottite</span>; its lithologies are broadly similar to those of Earth basalts and gabbros; i.e., crustal igneous rocks. The entire suite of <span class="hlt">shergottites</span> is characterized by a range of trace element, isotopic ratio, and oxygen fugacity values that mainly reflect compositional variations of the Martian mantle from which these magmas came. A newly found <span class="hlt">shergottite</span>, NWA 5298, was the focus of a study performed by scientists within the Astromaterials Research and Exploration Science (ARES) Directorate at the Johnson Space Center (JSC) in 2012. This sample was found in Morocco in 2008. Major element analyses were performed in the electron microprobe (EMP) laboratory of ARES at JSC, while the trace elements were measured at the University of Houston by laser inductively coupled plasma mass spectrometry (ICPMS). A detailed analysis of this stone revealed that this meteorite is a crystallized magma that comes from the enriched end of the <span class="hlt">shergottite</span> spectrum; i.e., trace element enriched and oxidized. Its oxidation comes in part from its mantle source and from oxidation during the magma ascent. It represents a pristine magma that did not mix with any other magma or see crystal accumulation or crustal contamination on its way up to the Martian surface. NWA 5298 is therefore a direct, albeit evolved, melt from the Martian mantle and, for its lithology (basaltic <span class="hlt">shergottite</span>), it represents the oxidized end of the <span class="hlt">shergottite</span> suite. It is thus a unique sample that has provided an end-member composition for Martian magmas.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20060021587','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20060021587"><span id="translatedtitle">Ar-Ar Dating of Martian Meteorite, Dhofar 378: An Early Shock Event?</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Park, J.; Bogard, D. D.</p> <p>2006-01-01</p> <p>Martian meteorite, Dhofar 378 (Dho378) is a basaltic <span class="hlt">shergottite</span> from Oman, weighing 15 g, and possessing a black fusion crust. Chemical similarities between Dho378 and the Los Angeles 001 <span class="hlt">shergottite</span> suggests that they might have derived from the same Mars locale. The plagioclase in other <span class="hlt">shergottites</span> has been converted to maskelenite by shock, but Dho378 apparently experienced even more intense shock heating, estimated at 55-75 GPa. Dho378 feldspar (approximately 43 modal %) melted, partially flowed and vesiculated, and then partially recrystallized. Areas of feldspathic glass are appreciably enriched in K, whereas individual plagioclases show a range in the Or/An ratio of approximately 0.18-0.017. Radiometric dating of martian <span class="hlt">shergottites</span> indicate variable formation times of 160-475 Myr, whereas cosmic ray exposure (CRE) ages of <span class="hlt">shergottites</span> indicate most were ejected from Mars within the past few Myr. Most determined Ar-39-Ar-40 ages of <span class="hlt">shergottites</span> appear older than other radiometric ages because of the presence of large amounts of martian atmosphere or interior Ar-40. Among all types of meteorites and returned lunar rocks, the impact event that initiated the CRE age very rarely reset the Ar-Ar age. This is because a minimum time and temperature is required to facilitate Ar diffusion loss. It is generally assumed that the shock-texture characteristics in martian meteorites were produced by the impact events that ejected the rocks from Mars, although the time of these shock events (as opposed to CRE ages) are not directly dated. Here we report Ar-39-Ar-40 dating of Dho378 plagioclase. We suggest that the determined age dates the intense shock heating event this meteorite experienced, but that it was not the impact that initiated the CRE age.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150001626','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150001626"><span id="translatedtitle">Peology and Geochemistry of New Paired Martian Meteorites 12095 and LAR 12240</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Funk, R. C.; Brandon, A. D.; Peslier, A.</p> <p>2015-01-01</p> <p>The meteorites LAR 12095 and LAR 12240 are believed to be paired Martian meteorites and were discovered during the Antarctic Search for Meteorites (ANSMET) 2012-2013 Season at Larkman Nunatak. The purpose of this study is to characterize these olivine-phyric <span class="hlt">shergottites</span> by analyzing all mineral phases for major, minor and trace elements and examining their textural relationships. The goal is to constrain their crystallization history and place these <span class="hlt">shergottites</span> among other Martian meteorites in order to better understand Martian geological history.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20070023926&hterms=United+States+History&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3D%2528%2528United%2BStates%2529%2BHistory%2529','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20070023926&hterms=United+States+History&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3D%2528%2528United%2BStates%2529%2BHistory%2529"><span id="translatedtitle">The Early Differentiation History of Mars from W-182-Nd-142 Isotope Systematics in the SNC Meteorites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Foley, C. Nicole; Wadhwa, M.; Borg, L. E.; Janney, P. E.; Hines, R.; Grove, T. L.</p> <p>2005-01-01</p> <p>We report here the results of an investigation of W and Nd isotopes in the SNC (<span class="hlt">Shergottite</span>-Nakhlite-Chassignite (martian)) meteorites. We have determined that epsilon W-182 values in the nakhlites are uniform within analytical uncertainties and have an average value of approx. 3. Also, while epsilon W-182 values in the <span class="hlt">shergottites</span> have a limited range (from 0.3-0.7), their epsilon Nd-142 values vary considerably (from -0.2-0.9). There appears to be no correlation between epsilon W-182 and epsilon Nd-142 in the nakhlites and <span class="hlt">shergottites</span>. These results shed new light on early differentiation processes on Mars, particularly on the timing and nature of fractionation in silicate reservoirs. Assuming a two-stage model, the metallic core is estimated to have formed at approx. 12 Myr after the beginning of the solar system. Major silicate differentiation established the nakhlite source reservoir before approx. 4542 Ma and the <span class="hlt">shergottite</span> source reservoirs at 4525 [sup +19 sub -21] Ma. These ages imply that, within the uncertainties afforded by the Hf-182-W-182 and Sm-146-Nd-142 chronometers, the silicate differentiation events that established the source reservoirs of the nakhlites and <span class="hlt">shergottites</span> may have occurred contemporaneously, possibly during crystallization of a global magma ocean. The distinct W-182-Nd-142 isotope systematics in the nakhlites and the <span class="hlt">shergottites</span> imply the presence of at least three isotopically distinct silicate reservoirs on Mars, two of which are depleted in incompatible lithophile elements relative to chondrites, and the third is enriched. The two depleted silicate reservoirs most likely reside in the Martian mantle, while the enriched reservoir could be either in the crust or the mantle. Therefore, the W-182-Nd-142 isotope systematics indicate that the nakhlites and the <span class="hlt">shergottites</span> originated from distinct source reservoirs and cannot be petrogenetically related. A further implication is that the source reservoirs of the nakhlites and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JGRE..120.2224B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JGRE..120.2224B"><span id="translatedtitle">The Pb isotopic evolution of the Martian mantle constrained by initial Pb in Martian meteorites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bellucci, J. J.; Nemchin, A. A.; Whitehouse, M. J.; Snape, J. F.; Bland, P.; Benedix, G. K.</p> <p>2015-12-01</p> <p>The Pb isotopic compositions of maskelynite and pyroxene grains were measured in ALH84001 and three enriched <span class="hlt">shergottites</span> (Zagami, Roberts Massif 04262, and Larkman Nunatuk 12011) by secondary ion mass spectrometry. A maskelynite-pyroxene isochron for ALH84001 defines a crystallization age of 4089 ± 73 Ma (2σ). The initial Pb isotopic composition of each meteorite was measured in multiple maskelynite grains. ALH84001 has the least radiogenic initial Pb isotopic composition of any Martian meteorite measured to date (i.e., 206Pb/204Pb = 10.07 ± 0.17, 2σ). Assuming an age of reservoir formation for ALH84001 and the enriched <span class="hlt">shergottites</span> of 4513 Ma, a two-stage Pb isotopic model has been constructed. This model links ALH84001 and the enriched <span class="hlt">shergottites</span> by their similar μ value (238U/204Pb) of 4.1-4.6 from 4.51 Ga to 4.1 Ga and 0.17 Ga, respectively. The model employed here is dependent on a chondritic μ value (~1.2) from 4567 to 4513 Ma, which implies that core segregation had little to no effect on the μ value(s) of the Martian mantle. The proposed Pb isotopic model here can be used to calculate ages that are in agreement with Rb-Sr, Lu-Hf, and Sm-Nd ages previously determined in the meteorites and confirm the young (~170 Ma) ages of the enriched <span class="hlt">shergottites</span> and ancient, >4 Ga, age of ALH84001.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20040056036&hterms=Samarium&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DSamarium','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20040056036&hterms=Samarium&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DSamarium"><span id="translatedtitle">Oxygen Fugacity of the Martian Mantle from Pigeonite/Melt Partitioning of Samarium, Europium and Gadolinium</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Musselwhite, D. S.; Jnes, J. H.; Shearer, C.</p> <p>2004-01-01</p> <p>This study is part of an ongoing effort to calibrate the pyroxene/melt REE oxybarometer for conditions relevant to the martian meteorites. These efforts have been motivated by reports of redox variations among the <span class="hlt">shergottites</span> . We have conducted experiments on martian composition pigeonite/melt rare earth element partitioning as a function of fO2.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015LPICo1856.5054N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015LPICo1856.5054N"><span id="translatedtitle">"Normal Planetary" Ne-Q in Chelyabinsk and Mars</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nyquist, L. E.; Park, J.; Nagao, K.; Haba, M. K.; Mikouchi, T.; Kusakabe, M.; Shih, C.-Y.; Herzog, G. F.</p> <p>2015-07-01</p> <p>Chelyabinsk contains “Q”-noble gases. Martian <span class="hlt">shergottite</span> Dhofar 378 contains trapped 20Ne/22Ne = 7.3±0.3, derivable from Q-Ne with 20Ne/22Ne = 10.67 via fractionation by solar wind induced sputtering. Martian juvenile Ne is suggested to be Q-Ne.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2013AGUFM.P51H..06B&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2013AGUFM.P51H..06B&link_type=ABSTRACT"><span id="translatedtitle">Evolution of the martian mantle as recorded by igneous rocks</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Balta, J. B.; McSween, H. Y.</p> <p>2013-12-01</p> <p>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 <span class="hlt">shergottite</span> 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 <span class="hlt">shergottite</span> 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 <span class="hlt">shergottite</span>-like parent magma. However, we show that the <span class="hlt">shergottite</span> magmas do resemble older martian rocks in composition and mineralogy. The Noachian-aged meteorite ALH 84001 has similar radiogenic-element signatures to the <span class="hlt">shergottites</span> and may derive from a similar mantle source despite the age difference2. Thus, <span class="hlt">shergottite</span>-like magmas may represent melting of mantle sources that were much more abundant early in martian history. We propose that the <span class="hlt">shergottites</span> 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</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5256989','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5256989"><span id="translatedtitle">Degree of equilibration of eucritic pyroxenes and thermal metamorphism of the earliest planetary crust</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Takeda, Hiroshi; Graham, A.L. Natural History Museum, London )</p> <p>1991-06-01</p> <p>The pyroxenes in two new monomict eucrites from Antarctica, <span class="hlt">Yamato</span> 791186 and <span class="hlt">Yamato</span> 792510, have been studied and compared with those of other Antarctic and non-Antarctic eucrites. The purpose of this study is to identify compositional and textural relationship shown by these pyroxenes which may be used as indicators of the thermal history of the meteorite. An attempt is made, using petrographic and compositional criteria, to distinguish between the initial cooling history and subsequent thermal events. It is suggested that it is possible to identify stages of thermal 'metamorphism' which may be used to indicate the conditions on the surface and crust of the parent body. A picture of the geological setting of the HED (Howardites, Eucrites, Diogenites) parent body is proposed, for which thermal metamorphism by impact heating is an important process. 22 refs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19920032188&hterms=mass+spectrometry+neutrons&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dmass%2Bspectrometry%2Bneutrons','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19920032188&hterms=mass+spectrometry+neutrons&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dmass%2Bspectrometry%2Bneutrons"><span id="translatedtitle">Exposure histories of lunar meteorites - ALHA81005, MAC88104, MAC88105, and Y791197</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nishiizumi, K.; Arnold, J. R.; Klein, J.; Fink, D.; Middleton, R.; Kubik, P. W.; Sharma, P.; Elmore, D.; Reedy, R. C.</p> <p>1991-01-01</p> <p>The cosmogenic radionuclides Ca-41, Cl-36, Al-26, and Be-10 in the Allan Hills 81005, MacAlpine Hills 88104, MacAlpine Hills 88105, and <span class="hlt">Yamato</span> 791197 meteorites were measured by accelerator mass spectrometry. Mn-53 in Allan Hills 81005 and <span class="hlt">Yamato</span> 791197 was measured by neutron activation. These four lunar meteorites experienced similar histories. They were ejected from near the surface of the moon ranging in depth down to 400 g/sq cm and had very short transition times (less than 0.1 Ma) from the moon to the earth. A comparison of the cosmogenic nuclide concentrations in MacAlpine Hills 88104 and MacAlpine Hills 88105 clearly indicates that they are a pair from the same fall.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20040062060&hterms=Samarium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DSamarium','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20040062060&hterms=Samarium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DSamarium"><span id="translatedtitle">Lunar and Planetary Science XXXV: Achondrites: An Awesome Assortment</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2004-01-01</p> <p>The session "chondrites: An Awesome Assortment" included the following reports:Nucleation of the Widmanstatten Pattern in Iron Meteorites; Compositions of the Group IVB Iron Meteorites; Sm-Nd Age and Initial 87Sr/86Sr for <span class="hlt">Yamato</span> 980318: An Old Cumulate Eucrite; Petrology of New Stannern-trend Eucrites and Eucrite Genesis; The Dichotomous HED Meteorite Suite; Early Thermal Evolution of HED Parent Body; Thermal History of the Lodranite <span class="hlt">Yamato</span> 74357: Constraints from Compositional Zoning and Fe-Mg Ordering; Late Thermal Evolution of Acapulcoites-Lodranites Parent Body: Evidence from Sm-Nd Isotopes and Trace Elements of the LEW 86220 Acapulcoite; Partial Melting Under Reducing Conditions: How are Primitive Achondrites Formed?; Evolution of the Ureilite Parent Body; Complex, Contrasting Behavior of Chromium During Late-Stage Processes in Ureilites; Sahara 99555 and D Orbigny: Possible Pristine Parent Magma of Quenched Angrites; and Devolatilized-Allende Partial Melts as an Analog for Primitive Angrite Magmas.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19820037373&hterms=Hares&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DHares','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19820037373&hterms=Hares&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DHares"><span id="translatedtitle">Organic analysis of the Antarctic carbonaceous chondrites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kotra, R. K.; Shimoyama, A.; Ponnamperuma, C.; Hare, P. E.; Yanai, K.</p> <p>1981-01-01</p> <p>Thus far, organic analysis of carbonaceous chondrites has proven the only fruitful means of examining complex organic matter of extraterrestrial origin. The present paper presents the results of organic analysis of two Antarctic meteorites, Allan Hills (77306) and <span class="hlt">Yamato</span> (74662), which may be considered free from terrestrial contamination. Ion-exchange chromatography, gas chromatography and mass spectrometery of meteorite samples reveal the presence in <span class="hlt">Yamato</span> of 15 and in Allan Hills of 20 protein and nonprotein amino acids, the most abundant of which are glycine and alanine. Abundances of the D and L enantiomers of each amino acid are also found to be nearly equal. Data thus indicate an abiotic extraterrestrial origin for the matter, and confirm a lack of terrestrial contamination.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015CoMP..169...13H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015CoMP..169...13H"><span id="translatedtitle">Mineralogical controls on garnet composition in the cratonic mantle</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hill, P. J. A.; Kopylova, M.; Russell, J. K.; Cookenboo, H.</p> <p>2015-02-01</p> <p>Garnet concentrates are a rich source of geochemical information on the mantle, but the mineralogical implications of wide ranging garnet compositions are poorly understood. We model chemical reactions between mantle minerals that may buffer the Ca-Cr <span class="hlt">lherzolitic</span> garnet trend common in the lithospheric mantle. A harzburgitic trend of garnet compositions featuring a lower increase in Cr with Ca relative to the conventional <span class="hlt">lherzolitic</span> trend is reported for the first time. Representation of garnet chemistry in terms of additive and exchange components in the Thompson space shows that the <span class="hlt">lherzolitic</span> and harzburgitic trends are controlled by the cation exchanges MgFeAl ↔ Ca2Cr and MgFeAl4 ↔ Ca2Cr4, respectively. Various equilibrium reactions are presented to explain the trends assuming a closed or open system mantle. The compositional variability of the natural garnets from the Canastra 8 kimberlite (Brazil) is modeled by a linear system of mass balance equations. The solution returns the reaction coefficients of products (positive values) and reactants (negative values), which are then evaluated against the observed mantle mineralogy. In the isochemical mantle, the <span class="hlt">lherzolitic</span> trend can form in the absence of clinopyroxene, but requires the presence of spinel and reflects the thickness of the spinel-garnet transition zone. This requirement contradicts observations on natural occurrences of the trend and the thermobarometry of the host peridotites. In the preferred model of a variably depleted mantle, the <span class="hlt">lherzolitic</span> trend critically depends on the presence of clinopyroxene. The occurrence of <span class="hlt">lherzolitic</span> garnet compositions in harzburgite can be explained by exhaustion of clinopyroxene as a result of garnet buffering. The open system behavior of the peridotitic mantle also provides a better explanation for the harzburgitic trend in garnet compositions. In an isochemical mantle, the trend can be controlled by many possible reactions, and no single mineral is</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JSAES..41..122R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JSAES..41..122R"><span id="translatedtitle">Petrology of ultramafic xenoliths in Cenozoic alkaline rocks of northern Madagascar (Nosy Be Archipelago)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rocco, Ivana; Lustrino, Michele; Zanetti, Alberto; Morra, Vincenzo; Melluso, Leone</p> <p>2013-01-01</p> <p>Late Miocene basanites of Nosy Be and Nosy Sakatia islands (Nosy Be Archipelago, northern Madagascar) carry spinel-facies anhydrous ultramafic xenoliths (<span class="hlt">lherzolites</span>, harzburgites and wehrlites). Geothermobarometric estimates indicate that these xenoliths derive from shallow mantle depths of 35-40 km, with those from Nosy Be island showing equilibration T (averages in the range of 945-985 °C) lower than the Nosy Sakatia analogues (averages ranging from 1010 to 1110 °C). One Nosy Sakatia mantle xenolith exhibits relatively fertile <span class="hlt">lherzolite</span> composition, with trace and major element mineral chemistry consistent with a residual character after low degrees (1-2%) of mafic melt extraction. We interpret this composition as that resembling a depleted mantle (DM)-like lithospheric composition before metasomatic overprints. The other <span class="hlt">lherzolites</span> and harzburgites display petrochemical characters consistent with variable extent of partial melting (up to 18%), associated with pronounced metasomatic overprints caused by migrating melts, as highlighted by enrichments in highly incompatible trace elements (e.g. light rare earth elements, LREE and Sr), together with the abundant occurrence of wehrlitic lithologies. The variability of petrochemical features points to different styles of metasomatism and metasomatic agents. The estimated composition of the parental melts of wehrlites matches that of host basanites. The combination of this evidence with the petrographic features, characterized by coarse-granular to porphyroclastic textures and by the presence of olivine without kink-banding, suggests that wehrlites are veins or pockets of high pressure cumulates within the mantle peridotite. The same melts also metasomatized via porous-flow percolation some <span class="hlt">lherzolites</span> and harzburgites. Distinctly, a group of <span class="hlt">lherzolites</span> and harzburgites was metasomatized by a different alkaline melt having markedly lower incompatible trace element contents. Late infiltration of metasomatic fluids</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120011125','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120011125"><span id="translatedtitle">What Lunar Meteorites Tell Us About the Lunar Highlands Crust</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Korotev, R. L.; Jolliff, B. L.; Zeigler, R. A.</p> <p>2012-01-01</p> <p>The first meteorite to be found1 that was eventually (1984) recognized to have originated from the Moon is <span class="hlt">Yamato</span> 791197. The find date, November 20, 1979, was four days after the end of the first Conference on the Lunar Highland Crust. Since then, >75 other lunar meteorites have been found, and these meteorites provide information about the lunar highlands that was not known from studies of the Apollo and Luna samples</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080013410','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080013410"><span id="translatedtitle">Sm-Nd for Norite 78236 and Eucrite Y980318/433: Implications for Planetary and Solar System Processes</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nyquist, L. E.; Shih, C-Y.; Reese, Y. D.</p> <p>2008-01-01</p> <p>Here, we compare Sm-147-Nd-143 and Sm-146-Nd-142 data for lunar norite 78236 to those for approximately 4.54-4.56 Ga old cumulate eucrite <span class="hlt">Yamato</span> 980318/433 and show that the norite data are compatible with its derivation from an isotopic reservoir similar to that from whence the eucrite pair came. Thus, lunar-like Sm-Nd isotopic systematics are not unique to the Earth-Moon system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20040062378&hterms=Breccia&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DBreccia','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20040062378&hterms=Breccia&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DBreccia"><span id="translatedtitle">Petrography of Lunar Meteorite PCA02007, a New Feldspathic Regolith Breccia</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zeigler, R. A.; Korotev, R. L.; Jolliff, B. L.</p> <p>2004-01-01</p> <p>PCA 02007 is a 22.4 g lunar meteorite collected in 2003 near the Pecora Escarpment in Antarctica [1]. PCA is a feldspathic regolith breccia composed of mature regolith. It is compositionally and texturally similar to other feldspathic lunar meteorites (FLMs) [2] and may be launch paired with <span class="hlt">Yamato</span> 791197 [3]. Here we present a petrographic description and compositions of mineral clasts, glass clasts, lithic clasts, and the bulk meteorite.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_14 --> <div id="page_15" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="281"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011GeCoA..75.6160R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011GeCoA..75.6160R"><span id="translatedtitle">Mineralogical and geochemical constraints on the shallow origin, ancient veining, and multi-stage modification of the Lherz peridotite</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Riches, Amy J. V.; Rogers, Nick W.</p> <p>2011-10-01</p> <p>New major- and trace-element data of bulk-rocks and constituent minerals, and whole-rock Re-Os isotopic compositions of samples from the Lherz Massif, French Pyrenees, reveal complex petrological relationships between the dominant lithologies of <span class="hlt">lherzolite</span> ± olivine-websterite and harzburgite. The Lherz peridotite body contains elongate, foliation parallel, lithological strips of harzburgite, <span class="hlt">lherzolite</span>, and olivine-websterite cross-cut by later veins of hornblende-bearing pyroxenites. Peridotite lithologies are markedly bimodal, with a clear compositional gap between harzburgites and <span class="hlt">lherzolites</span> ± olivine-websterite. Bulk-rock and mineral major-element oxide (Mg-Fe-Si-Cr) compositions show that harzburgites are highly-depleted and result from ˜20-25 wt.% melt extraction at pressures <2 GPa. Incompatible and moderately-compatible trace-element abundances of hornblendite-free harzburgites are analogous to some mantle-wedge peridotites. In contrast, <span class="hlt">lherzolites</span> ± olivine-websterite overlap estimates of primitive mantle composition, yet these materials are composite samples that represent physical mixtures of residual <span class="hlt">lherzolites</span> and clinopyroxene dominated cumulates equilibrated with a LREE-enriched tholeiitic melt. Trace-element compositions of harzburgite, and some <span class="hlt">lherzolite</span> bulk-rocks and pyroxenes have been modified by; (1) wide-spread interaction with a low-volume LREE-enriched melt +/- fluid that has disturbed highly-incompatible elements (e.g., LREEs, Zr) without enrichment of alkali- and Ti-contents; and (2) intrusion of relatively recent, small-volume, hornblendite-forming, basanitic melts linked to modal and cryptic metasomatism resulting in whole-rock and pyroxene Ti, Na and MREE enrichment. Rhenium-Os isotope systematics of Lherz samples are also compositionally bimodal; <span class="hlt">lherzolites</span> ± olivine-websterite have chondritc to suprachondritic 187Os/ 188Os and 187Re/ 188Os values that overlap the range reported for Earth's primitive upper mantle, whereas</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140002778','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140002778"><span id="translatedtitle">Water Contents of the Mantle Beneath the Rio Grande Rift: FTIR Analysis of Kilbourne Hole Peridotite Xenoliths</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Schaffer, Lillian A.; Peslier, Anne; Brandon, Alan</p> <p>2013-01-01</p> <p>Although nominally anhydrous mantle minerals contain only trace amounts of water, they are the main reservoir of water in the mantle. Added up at the scale of the Earth's mantle, these trace amounts of water represent oceans worth in mass]. Mantle xenoliths from Kilbourne Hole in southern New Mexico are ideal to study mantle water distribution in a rift tectonic setting as they come from a recently-erupted maar in the middle of the Rio Grande Rift. Eleven <span class="hlt">lherzolites</span>, one harzburgite, and one dunite are being analyzed for water contents by FTIR. The xenoliths will also be analyzed for major and trace element composition, Fe3+/Summation (Fe) ratios, and characterized petrologically. Olivines exhibit variable water contents with less water at the rims compared to the cores. This is probably due to H loss during decompression and xenolith transport by the host magma. Mantle water contents appear to have been primarily preserved in the core of the olivines, based on diffusion modeling of the typically plateau-shaped water content profiles across these grains. Water concentrations are in equilibrium between clino- and orthopyroxene, but olivine concentrations are typically not in equilibrium with those of either pyroxene. <span class="hlt">Lherzolites</span> analyzed so far have water contents of 2-12 ppm H2O in olivines, 125-165 ppm H2O in orthopyroxenes, and 328-447 ppm H2O in clinopyroxenes. These water contents are similar to, but with a narrower range, than those for the respective minerals in other continental peridotite xenoliths. The <span class="hlt">lherzolites</span> have bulk-rock (BR) Al2O3 contents that range between 3.17 and 3.78 wt%, indicating similar degrees of partial melting, which could explain the narrow range of their pyroxene water contents. Primitive mantle normalized rare earth element (REE) profiles of the bulk <span class="hlt">lherzolites</span> vary from light REE depleted to flat, with no significant differences between, nor relation to, their mineral water contents. Consequently, the metasomatic agents that</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050182099','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050182099"><span id="translatedtitle">Metamorphosed CM and CI Carbonaceous Chondrites Could Be from the Breakup of the Same Earth-crossing Asteroid</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zolensky, Michael; Abell, Paul; Tonui, Eric</p> <p>2005-01-01</p> <p>Far from being the relatively unprocessed materials they were once believed to be, we now know that a significant number of carbonaceous chondrites were thermally metamorphosed on their parent asteroid(s). Numerous studies indicate that 7 "CM" and 2 "CI" chondrites have been naturally heated, variously, at from 400 to over 700 C on their parent asteroid(s). Petrographic textures reveal that this thermal metamorphism occurred after the dominant aqueous alteration phase, although some meteorites show evidence of a heating event between two aqueous alteration episodes, i.e. pro- and retrograde aqueous alteration. Aside from the issues of the identification of the transient heat source, timing of metamorphism, and the relation of these materials (if any) to conventional CM and CI chondrites, there is also a mystery related to their recovery. All of these meteorites have been recovered from the Antarctic; none are falls or finds from anyplace else. Indeed, the majority have been collected by the Japanese NIPR field parties in the <span class="hlt">Yamato</span> Mountains. In fact, one estimate is that these meteorites account for approx. 64 wt% of the CM carbonaceous chondrites at the NIPR. The reasons for this are unclear and might be due in part to simple sampling bias. However we suggest that this recovery difference is related to the particular age of the <span class="hlt">Yamato</span> Mountains meteorite recovery surfaces, and differences in meteoroid fluxes between the <span class="hlt">Yamato</span> meteorites and recent falls and substantially older Antarctic meteorites. Additional information is included in the original extended abstract.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/945809','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/945809"><span id="translatedtitle">Olivine compositions from the Hawaii Scientific Drilling Project, Phase 2: Evidence for a peridotite mantle source region</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Putirka, K D; Ryerson, F J</p> <p>2008-10-27</p> <p>To the extent that mantle plumes reflect whole mantle convection, Hawaii may provide the clearest window into Earth's lower mantle. Samples from the Hawaii Scientific Drilling Project (HSDP) thus provide valuable tests for models of mantle mineralogy and composition. In this vein, it has been argued recently that Hawaiian olivines, especially those from the shield-building phase as sampled by HSDP, are so high in Ni (Sobolev et al., 2005, 2007), and that Hawaiian whole rocks are so low in CaO (Herzberg, 2006) and high in SiO{sub 2} (Hauri, 1996) that a peridotite mantle source cannot generate such compositions. The Hawaiian plume, so the argument goes, is thus supposedly rich in pyroxenite, and possibly olivine-free. However, comparisons of HSDP olivines to <span class="hlt">lherzolites</span>, and HSDP whole rocks to <span class="hlt">lherzolites</span> and partial melting experiments belie these premises. Testable predictions of the pyroxenite model also fail. New comparisons instead show that Hawaiian lavas can be produced from a peridotite source. First, it is unclear that the Hawaiian source is enriched in NiO. The NiO contents of olivines hosted by <span class="hlt">lherzolites</span> (GEOROC) have the same range as olivines from the HSDP; indeed, the maximum NiO for olivines from <span class="hlt">lherzolites</span> (0.6 wt.%) is as high as that reported for olivines from any oceanic volcano locality. There is a compositional separation between <span class="hlt">lherzolite</span>- and HSDP-hosted olivines. But HSDP olivines are not NiO enriched so much as <span class="hlt">lherzolite</span> olivines are higher in Fo at a given NiO. Lower Fo contents at Hawaii (at a given NiO) ensue because olivine compositions there follow a liquid line of descent, where both Ni and Mg decrease with differentiation. In contrast, subsolidus equilibria involving orthopyroxene enforce a higher and less variable Fo content for <span class="hlt">lherzolite</span>-derived olivines. Moreover, the pyroxenite mantle model predicts that whole rocks with low CaO and high SiO{sub 2} should host olivines with high NiO. But in HSDP samples, neither correlation</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003E%26PSL.214...27M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003E%26PSL.214...27M"><span id="translatedtitle">Volatiles (nitrogen, noble gases) in recently discovered SNC meteorites, extinct radioactivities and evolution</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mathew, K. J.; Marty, B.; Marti, K.; Zimmermann, L.</p> <p>2003-09-01</p> <p>We report noble gas and nitrogen analyses of newly discovered SNC meteorites, one nakhlite (NWA817) and four <span class="hlt">shergottites</span> (NWA480, NWA856, NWA1068, and SaU 005). The K-Ar age (1.3 Ga) as well as the cosmic-ray exposure (CRE) age (10.0±1.3 Ma) of nakhlite NWA817 agree with data of Nakhla. The CRE ages of NWA480, NWA856, and NWA1068 (2.35±0.20, 2.60±0.21 and 2.01±0.65 Ma, respectively) are consistent, within uncertainties, with other basaltic <span class="hlt">shergottites</span>, but the CRE age of SaU 005 (1.25±0.07 Ma) is distinct and indicates a different ejection event. Bulk K-Ar ages of all <span class="hlt">shergottites</span> exceed the reported radiometric ages and reveal the presence of inherited radiogenic 40Ar in basaltic lavas. The isotopic composition of nitrogen trapped in these SNC meteorites is not homogeneous, since δ 15N values of either +15 to 20‰ or +45‰, indicate different nitrogen reservoirs. All <span class="hlt">shergottites</span> contain fission xenon from 238U, and fission Xe of extinct ( T1/2=82 Ma) 244Pu, previously identified in ALH84001, in Chassigny and in Nakhla is also present in at least one <span class="hlt">shergottite</span> (NWA856). The <span class="hlt">shergottites</span> contain less fissiogenic Xe than other SNC, suggesting that either their source was more degassed or that the magma source region closed at a later time. In nakhlites, fission xenon from 244Pu correlates with uranium, a geochemical proxy of plutonium. Thus it is possible that fissiogenic Xe was not inherited during magma differentiation, but rather was produced in situ and retained in refractory mineral assemblages. In this interpretation, the magma evolution that settled the mineralogy and geochemistry of nakhlites took place at a time when 244Pu was alive and pre-dated the (late) events recorded in their radiometric ages. Alternatively, fissiogenic xenon was trapped from a mantle source during closed system evolution of the parent magmas, in which case such evolution might have taken place at considerable depth (pressure) in order to inhibit magma degassing during the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1997GeCoA..61..161C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1997GeCoA..61..161C"><span id="translatedtitle">Oxygen isotopic composition of hydrous and anhydrous mantle peridotites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chazot, Gilles; Lowry, David; Menzies, Martin; Mattey, David</p> <p>1997-01-01</p> <p>Oxygen isotope ratios, determined using the laser fluorination technique, are reported for minerals from anhydrous and hydrous (i.e., amphibole-bearing) spinel <span class="hlt">lherzolites</span> from Yemen, as well as from hydrous spinel <span class="hlt">lherzolites</span> and amphibole megacrysts from Nunivak Island, Alaska. Oxygen isotopic compositions of olivine vary from 5.1-5.4%c and of pyroxene from 5.5-6.0%c and no systematic difference exists between minerals in hydrous and anhydrous <span class="hlt">lherzolites</span>. The oxygen isotopic composition of the amphibole in the peridotites and of the amphibole megacrysts is also very homogeneous and varies from δ 18O = 5.3-5.6%o. These results indicate that the metasomatic minerals in the <span class="hlt">lherzolites</span> are in oxygen isotopic equilibrium with the peridotitic minerals. The only isotopic disequilibria are observed in minerals which have grown in melt-pockets formed by partial melting of amphibole. The homogeneity of the oxygen isotopic ratios of mantle minerals in this study indicate that the fluids circulating in the mantle and precipitating amphibole or mica had the same oxygen isotopic compositions as the mantle protolith or that the fluids had been buffered by the isotopic composition of the olivine, the most abundant mineral, during percolation through the peridotites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015EGUGA..1711482F&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015EGUGA..1711482F&link_type=ABSTRACT"><span id="translatedtitle">Crystal preferred orientations of minerals from mantle xenoliths in alkali basaltic rocks form the Catalan Volcanic Zone (NE Spain)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fernández-Roig, Mercè; Galán, Gumer; Mariani, Elisabetta</p> <p>2015-04-01</p> <p>Mantle xenoliths in alkali basaltic rocks from the Catalan Volcanic Zone, associated with the Neogene-Quaternary rift system in NE Spain, are formed of anhydrous spinel <span class="hlt">lherzolites</span> and harzburgites with minor olivine websterites. Both peridotites are considered residues of variable degrees of partial melting, later affected by metasomatism, especially the harzburgites. These and the websterites display protogranular microstructures, whereas <span class="hlt">lherzolites</span> show continuous variation between protogranular, porphyroclastic and equigranular forms. Thermometric data of new xenoliths indicate that protogranular harzburgites, <span class="hlt">lherzolites</span> and websterites were equilibrated at higher temperatures than porphyroclastic and equigranular <span class="hlt">lherzolites</span>. Mineral chemistry also indicates lower equilibrium pressure for porphyroclastic and equigranular <span class="hlt">lherzolites</span> than for the protogranular ones. Crystal preferred orientations (CPOs) of olivine and pyroxenes from these new xenoliths were determined with the EBSD-SEM technique to identify the deformation stages affecting the lithospheric mantle in this zone and to assess the relationships between the deformation fabrics, processes and microstructures. Olivine CPOs in protogranular harzburgites, <span class="hlt">lherzolites</span> and a pyroxenite display [010]-fiber patterns characterized by a strong point concentration of the [010] axis normal to the foliation and girdle distribution of [100] and [001] axes within the foliation plane. Olivine CPO symmetry in porphyroclastic and equigranular <span class="hlt">lherzolites</span> varies continuously from [010]-fiber to orthorhombic and [100]-fiber types. The orthorhombic patterns are characterized by scattered maxima of the three axes, which are normal between them. The rare [100]-fiber patterns display strong point concentration of [100] axis, with normal girdle distribution of the other two axes, which are aligned with each other. The patterns of pyroxene CPOs are more dispersed than those of olivine, especially for clinopyroxene, but</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010M%26PS...45..495B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010M%26PS...45..495B"><span id="translatedtitle">Geochemistry of the Martian meteorite ALH84001, revisited</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Barrat, Jean-Alix; Bollinger, Claire</p> <p>2010-04-01</p> <p>Major and trace element abundances were determined on powders prepared from four distinct chips from Allan Hills (ALH) 84001 to constrain the bulk rock composition, and to assess the trace element abundances of orthopyroxenes and phosphates. Our new determinations were used to evaluate the composition of the parental melt of this stone. An unrealistic light rare earth element (REE)-enriched parental melt is calculated from the composition of the orthopyroxene and relevant equilibrium partition coefficients. The involvement of a small amount of trapped melt and subsolidus reequilibrations between orthopyroxene and the interstitial phases can account for this discrepancy. A parental melt that displays a trace element pattern (REE, Zr, and Hf) that closely resembles enriched <span class="hlt">shergottites</span> such as Zagami or Los Angeles is calculated if these effects are taken into account. These results suggest that some <span class="hlt">shergottitic</span> melts were already erupted on Mars during the Noachian.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20000094532&hterms=Dunite&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DDunite','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20000094532&hterms=Dunite&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DDunite"><span id="translatedtitle">Radiometric Ages of Martian Meteorites compared to Martian Surfaces Ages</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nyquist, L. E.; Shih, C.-Y.</p> <p>1999-01-01</p> <p>The surprisingly young Rb-Sr age of the Shergotty meteorite contributed to early suggestions that it might be of martian origin. their redox state and oxygen isotopic compositions linked the <span class="hlt">shergottites</span> to the clino-pyroxenite nakhlites and the dunite Chassigny, causing them to be grouped as SNC meteorites. These characteristics, but especially the similarity of the elemental and isotopic compositions of gases trapped in <span class="hlt">shergottites</span> to those of the martian atmosphere, have caused the martian origin of the SNC and related meteorites to be widely accepted. Although the young ages were one of the early hints of a martian origin for the SNC meteorites, their interpretation has remained somewhat ambiguous. We will review the radiometric ages of the martian meteorites and attempt to place them into the context of martian surface ages.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110011532','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110011532"><span id="translatedtitle">Effect of Cooling Rate and Oxygen Fugacity on the Crystallization of the Queen Alexandra Range 94201 Martian Melt Composition</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Koizumi, E.; Mikouchi, T.; McKay, G.; Schwandt, C.; Monkawa, A.; Miyamoto, M.</p> <p>2002-01-01</p> <p>Although many basaltic <span class="hlt">shergottites</span> have been recently found in north African deserts, QUE94201 basaltic <span class="hlt">shergottite</span> (QUE) is still important because of its particular mineralogical and petrological features. This meteorite is thought to represent its parent melt composition [1 -3] and to crystallize under most reduced condition in this group [1,4]. We performed experimental study by using the synthetic glass that has the same composition as the bulk of QUE. After homogenization for 48 hours at 1300 C, isothermal and cooling experiments were done under various conditions (e.g. temperature, cooling rates, and redox states). Our goals are (1) to verify that QUE really represents its parent melt composition, (2) to estimate a cooling rate of this meteorite, (3) to clarify the crystallization sequences of present minerals, and (4) to verity that this meteorite really crystallized under reduced condition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFM.T21H..05M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.T21H..05M"><span id="translatedtitle">Melt Impregnation, Strain Localization, and Deformation Mechanisms in a Fossil Oceanic Fracture Zone (Ingalls Ophiolite)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Miller, R. B.; Gordon, S. M.</p> <p>2010-12-01</p> <p>A steep mantle shear zone that deforms ultramafic rocks of the Jurassic Ingalls ophiolite is inferred to preserve a record of the interplay of melt impregnation, strain localization, and switching deformation mechanisms in a fossil oceanic fracture zone. This ~2-km-wide, E-W-striking shear zone separates harzburgite and dunite on the south from <span class="hlt">lherzolite</span> and cpx-rich harzburgite on the north. Geochemical data from the <span class="hlt">lherzolite</span>, which contains veinlets of plagioclase and cpx, suggest impregnation by infiltrating basaltic melt. The shear zone reworks the <span class="hlt">lherzolite</span> unit, but also contains widespread plagioclase peridotite and hornblende peridotite, and shear-zone mylonites are less depleted than the adjacent units. Olivine is reduced in average grain size from 1.5-3.0 mm in the <span class="hlt">lherzolites</span> to 50 µm in some mylonites. In the mylonites, opx and cpx porphyroclasts are set in a mosaic of olivine, cpx, opx +/- hornblende +/- plagioclase. Lattice preferred orientations (LPO) determined by EBSD indicate that olivine in the dunite-harzburgite and <span class="hlt">lherzolite</span> units deformed by glide on [100] (010), a common mechanism for dislocation creep in the upper mantle. In contrast, olivine in the mylonites has much weaker, poorly defined LPOs. This weakening of the LPO and the microstructures are compatible with dynamic recrystallization and grain-size reduction resulting from dislocation creep leading to a change to a grain-size-sensitive deformation mechanism. We suggest that impregnation by infiltrating melts may have helped localize strain, and the formation of multiple phases, in part as a result of impregnation, may have stabilized the small olivine grain size.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011CoMP..162..889M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011CoMP..162..889M"><span id="translatedtitle">Metasomatized lithospheric mantle beneath Turkana depression in southern Ethiopia (the East Africa Rift): geochemical and Sr-Nd-Pb isotopic characteristics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Meshesha, Daniel; Shinjo, Ryuichi; Matsumura, Risa; Chekol, Takele</p> <p>2011-11-01</p> <p>Mantle xenoliths entrained in Quaternary alkaline basalts from the Turkana Depression in southern Ethiopia (the East Africa Rift) were studied for their geochemical and Sr-Nd-Pb isotopic compositions to constrain the evolution of the lithosphere. The investigated mantle xenoliths are spinel <span class="hlt">lherzolites</span> in composition with a protogranular texture. They can be classified into two types: anhydrous and hydrous spinel <span class="hlt">lherzolites</span>; the latter group characterized by the occurrences of pargasite and phlogopite. The compositions of whole-rock basaltic component (CaO = 3.8-5.6 wt%, Al2O3 = 2.5-4.1 wt%, and MgO = 34.7-38.1 wt%), spinel (Cr# = 0.062-0.117, Al2O3 = 59.0-64.4 wt%) and clinopyroxene (Mg# = 88.4-91.7, Al2O3 = 5.2-6.7 wt%) indicate that the <span class="hlt">lherzolites</span> are fertile and have not experienced significant partial melting. Both types are characterized by depleted 87Sr/86Sr (0.70180-0.70295) and high 143Nd/144Nd (0.51299-0.51348) with wide ranges of 206Pb/204Pb (17.86-19.68) isotopic compositions. The variations of geochemical and isotopic compositions can be explained by silicate metasomatism induced by different degree of magma infiltrations from ascending mantle plume. The thermobarometric estimations suggest that the spinel <span class="hlt">lherzolites</span> were derived from depths of 50-70 km (15.6-22.2 kb) and entrained in the alkaline magma at 847-1,052°C. Most of the spinel <span class="hlt">lherzolites</span> from this study record an elevated geotherm (60-90 mW/m2) that is related to the presence of rising mantle plume in an active tectonic setting. Sm-Nd isotopic systematic gives a mean TDM model age of 0.95 Ga, interpreted as the minimum depletion age of the subcontinental lithosphere beneath the region.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010JGeo...49..261G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010JGeo...49..261G"><span id="translatedtitle">Mineral chemical composition and geodynamic significance of peridotites from Nain ophiolite, central Iran</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ghazi, Javad Mehdipour; Moazzen, Mohssen; Rahgoshay, Mohammad; Moghadam, Hadi Shafaii</p> <p>2010-05-01</p> <p>The peridotites from north of the town of Nain in central Iran consist of clinopyroxene-bearing harzburgite and <span class="hlt">lherzolite</span> with small lenses of dunite and chromitite pods. The <span class="hlt">lherzolite</span> contains aluminous spinel with a Cr number (Cr # = Cr/[Cr + Al]) of 0.17. The Cr number of spinels in harzburgite and chromitite is 0.38-0.42 and 0.62, respectively. This shows that the <span class="hlt">lherzolite</span> and harzburgite resulted from <18% of partial melting of the source materials. The estimated temperature is 1100 ± 200 °C for peridotites, the estimated pressure is <15 ± 2.3 kbar for harzburgites and >16 ± 2.3 kbar for <span class="hlt">lherzolites</span> and estimated fo2 is 10 -1±0.5 for peridotites. Discriminant geochemical diagrams based on mineral chemistry of harzburgites indicate a supra-subduction zone (SSZ) to mid-oceanic ridge (MOR) setting for these rocks. On the basis of their Cr #, the harzburgite and <span class="hlt">lherzolite</span> spinels are analogous to those from abyssal peridotites and oceanic ophiolites, whereas the chromites in the chromitite (on the basis of Cr # and boninitic nature of parental melts) resemble those from SSZ ophiolitic sequences. Therefore, the Nain ophiolite complex most likely originated in an oceanic crust related to supra-subduction zone, i.e. back arc basin. Field observations and mineral chemistry of the Nain peridotites, indicating the suture between the central Iran micro-continent (CIM) block and the Sanandaj-Sirjan zone, show that these peridotites mark the site of the Nain-Baft seaway, which opened with a slow rate of ocean-floor spreading behind the Mesozoic arc of the Sanandaj-Sirjan zone as a result of change of Neo Tethyan subduction régime during middle Cretaceous.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70010791','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70010791"><span id="translatedtitle">Maskelynite: Formation by explosive shock</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Milton, D.J.; De Carli, P. S.</p> <p>1963-01-01</p> <p>When high pressure (250 to 300 kilobars) was applied suddenly (shock-loading) to gabbro, the plagioclase was transformed to a noncrystalline phase (maskelynite) by a solid-state reaction at a low temperature, while the proxene remained crystalline. The shock-loaded gabbro resembles meteorites of the <span class="hlt">shergottite</span> class; this suggests that the latter formed as a result of shock. The shock-loading of gabbro at 600 to 800 kilobars raised the temperature above the melting range of the plagioclase.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20040059917&hterms=Weathering&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DWeathering','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20040059917&hterms=Weathering&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DWeathering"><span id="translatedtitle">Lunar and Planetary Science XXXV: Martian Meteorites: Chemical Weathering</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2004-01-01</p> <p>The session "Martian Meteorites: Chemical Weathering" included the following reports:Chemical Weathering Records of Martian Soils Preserved in the Martian Meteorite EET79001; Synchrotron X-Ray Diffraction Analysis of Meteorites in Thin Section: Preliminary Results; A Survey of Olivine Alteration Products Using Raman Spectroscopy; and Rb-Sr and Sm-Nd Isotope Systematics of <span class="hlt">Shergottite</span> NWA 856: Crystallization Age and Implications for Alteration of Hot Desert SNC Meteorites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20100009797','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20100009797"><span id="translatedtitle">Is EETA79001 Lithology B A True Melt Composition?</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Arauza, S. J.; Jones, John H.; Mittlefehldt, D. W.; Le, L.</p> <p>2010-01-01</p> <p>EETA79001 is a member of the SNC (<span class="hlt">shergottite</span>, nakhlite, chassignite) group of Martian meteorites. Most SNC meteorites are cumulates or partial cumulates [1] inhibiting calculation of parent magma compositions; only two (QUE94201 and Y- 980459) have been previously identified as true melt compositions. The goal of this study is to test whether EETA79001-B may also represent an equilibrium melt composition, which could potentially expand the current understanding of martian petrology.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20160007506','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20160007506"><span id="translatedtitle">Petrology and Geochemistry of New Paired Martian Meteorites Larkman Nunatak 12240 and Larkman Nunatak 12095</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Funk, R. C.; Peslier, A. H.; Brandon, A. D.; Humayun, M.</p> <p>2016-01-01</p> <p>Two of the latest Martian meteorites found in Antarctica, paired olivine-phyric <span class="hlt">shergottites</span> LAR 12240 and LAR 12095, are described in order to decipher their petrological context, and place constraints on the geological history of Mars. This project identifies all phases found in LAR 12240 and 12095 and analyzes them for major and trace elements. The textural relationships among these phases are examined in order to develop a crystallization history of the magma(s) that formed these basalts.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080026098','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080026098"><span id="translatedtitle">Characterization and Petrologic Interpretation of Olivine-Rich Basalts at Gusev Crater, Mars</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>McSween, H. Y.; Wyatt, M. B.; Gellert, R.; Bell, J. F., III; Morris, R. V.; Herkenhoff, K. E.; Crumpler, L. S.; Milam, K. A.; Stockstill, K. R.; Tornabene, L. L.; Arvidson, R. E.; Bartlett, P.; Blaney, D.; Cabrol, N. A.; Christensen, P. R.; Clark, B. C.; Crisp, A.; DesMarais, D. J.; Economou, T.; Farmer, J. D.; Farrand, W.; Ghosh, A.; Golombek, M.; Gorevan, S.; Greeley, R.</p> <p>2006-01-01</p> <p>Rocks on the floor of Gusev crater are basalts of uniform composition and mineralogy. Olivine, the only mineral to have been identified or inferred from data by all instruments on the Spirit rover, is especially abundant in these rocks. These picritic basalts are similar in many respects to certain Martian meteorites (olivine-phyric <span class="hlt">shergottites</span>). The olivine megacrysts in both have intermediate compositions, with modal abundances ranging up to 20-30%. Associated minerals in both include low-calcium and high-calcium pyroxenes, plagioclase of intermediate composition, iron-titanium-chromium oxides, and phosphate. These rocks also share minor element trends, reflected in their nickel-magnesium and chromium-magnesium ratios. Gusev basalts and <span class="hlt">shergottites</span> appear to have formed from primitive magmas produced by melting an undepleted mantle at depth and erupted without significant fractionation. However, apparent differences between Gusev rocks and <span class="hlt">shergottites</span> in their ages, plagioclase abundances, and volatile contents preclude direct correlation. Orbital determinations of global olivine distribution and compositions by thermal emission spectroscopy suggest that olivine-rich rocks may be widespread. Because weathering under acidic conditions preferentially attacks olivine and disguises such rocks beneath alteration rinds, picritic basalts formed from primitive magmas may even be a common component of the Martian crust formed during ancient and recent times.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20090012324','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20090012324"><span id="translatedtitle">LU-HF Age of Martian Meteorite Larkman Nunatek 06319</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Shafer, J. T.; Brandon, A. D.; Lapen, T. J.; Righter, M.; Beard, B.; Peslier, A. H.</p> <p>2009-01-01</p> <p>Lu-Hf isotopic data were collected on mineral separates and bulk rock powders of LAR 06319, yielding an age of 197+/- 29 Ma. Sm-Nd isotopic data and in-situ LA-ICP-MS data from a thin section of LAR 06319 are currently being collected and will be presented at the 2009 LPSC. These new data for LAR 06319 extend the existing data set for the enriched <span class="hlt">shergottite</span> group. Martian meteorites represent the only opportunity for ground truth investigation of the geochemistry of Mars [1]. At present, approximately 80 meteorites have been classified as Martian based on young ages and distinctive isotopic signatures [2]. LAR 06319 is a newly discovered (as part of the 2006 ANSMET field season) martian meteorite that represents an important opportunity to further our understanding of the geochemical and petrological constraints on the origin of Martian magmas. Martian meteorites are traditionally categorized into the <span class="hlt">shergottite</span>, nakhlite, and chassignite groups. The <span class="hlt">shergottites</span> are further classified into three distinct isotopic groups designated depleted, intermediate, and enriched [3,4] based on the isotope systematics and compositions of their source(s).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70031054','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70031054"><span id="translatedtitle">Characterization and petrologic interpretation of olivine-rich basalts at Gusev Crater, Mars</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>McSween, H.Y.; Wyatt, M.B.; Gellert, Ralf; Bell, J.F.; Morris, R.V.; Herkenhoff, K. E.; Crumpler, L.S.; Milam, K.A.; Stockstill, K.R.; Tornabene, L.L.; Arvidson, R. E.; Bartlett, P.; Blaney, D.; Cabrol, N.A.; Christensen, P.R.; Clark, B. C.; Crisp, J.A.; Des Marais, D.J.; Economou, T.; Farmer, J.D.; Farrand, W.; Ghosh, A.; Golombek, M.; Gorevan, S.; Greeley, R.; Hamilton, V.E.; Johnson, J. R.; Joliff, B.L.; Klingelhofer, G.; Knudson, A.T.; McLennan, S.; Ming, D.; Moersch, J.E.; Rieder, R.; Ruff, S.W.; Schrorder, C.; de Souza, P.A.; Squyres, S. W.; Wanke, H.; Wang, A.; Yen, A.; Zipfel, J.</p> <p>2006-01-01</p> <p>Rocks on the floor of Gusev crater are basalts of uniform composition and mineralogy. Olivine, the only mineral to have been identified or inferred from data by all instruments on the Spirit rover, is especially abundant in these rocks. These picritic basalts are similar in many respects to certain Martian meteorites (olivine-phyric <span class="hlt">shergottites</span>). The olivine megacrysts in both have intermediate compositions, with modal abundances ranging up to 20-30%. Associated minerals in both include low-calcium and high-calcium pyroxenes, plagioclase of intermediate composition, iron-titanium-chromium oxides, and phosphate. These rocks also share minor element trends, reflected in their nickel-magnesium and chromium-magnesium ratios. Gusev basalts and <span class="hlt">shergottites</span> appear to have formed from primitive magmas produced by melting an undepleted mantle at depth and erupted without significant fractionation. However, apparent differences between Gusev rocks and <span class="hlt">shergottites</span> in their ages, plagioclase abundances, and volatile contents preclude direct correlation. Orbital determinations of global olivine distribution and compositions by thermal emission spectroscopy suggest that olivine-rich rocks may be widespread. Because weathering under acidic conditions preferentially attacks olivine and disguises such rocks beneath alteration rinds, picritic basalts formed from primitive magmas may even be a common component of the Martian crust formed during ancient and recent times. Copyright 2006 by the American Geophysical Union.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940011917','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940011917"><span id="translatedtitle">The dregs of crystallization in Zagami</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mccoy, T. J.; Keil, K.; Taylor, G. J.</p> <p>1993-01-01</p> <p>The Zagami <span class="hlt">shergottite</span> is a basaltic meteorite which formed when a phenocryst-bearing lava flow was emplaced at or near the surface of Mars. Recently, a cm-sized olivine-rich lithology has been identified in Zagami by Mossbauer spectroscopy. Olivine is extremely rare in <span class="hlt">shergottites</span>, particularly in Zagami and Shergotty, where it occurs only as minute grains. We report petrologic and microprobe studies of this olivine-rich lithology. This material represents the last few percent of melt and is highly enriched in phosphates, opaques and mesostases, all of which are late-stage crystallization products. Phosphates replaced augite as a phenocryst phase when the magma became saturated in P. This late stage melt also includes a fayalite-bearing, multi-phase intergrowth which crystallized after the melt became too rich in iron to crystallize pigeonite. We can now reconstruct the entire crystallization history of the Zagami <span class="hlt">shergottite</span> from a deep-seated magma chamber to crystallization of the final few percent of melt in a near-surface dike or thick flow. Small pockets (tens of microns) of late-stage melt pockets are ubiquitous but volumetrically minor in Zagami. We do not know the physical relationship between these areas and the cm-sized olivine-rich material described here. It is possible that these small pockets were mobile, forming larger areas. Perhaps inspection of the entire hand specimen of Zagami would clarify this relationship.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016M%26PS..tmp..321W&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016M%26PS..tmp..321W&link_type=ABSTRACT"><span id="translatedtitle">The chlorine isotopic composition of Martian meteorites 1: Chlorine isotope composition of Martian mantle and crustal reservoirs and their interactions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Williams, J. T.; Shearer, C. K.; Sharp, Z. D.; Burger, P. V.; McCubbin, F. M.; Santos, A. R.; Agee, C. B.; McKeegan, K. D.</p> <p>2016-05-01</p> <p>The Martian meteorites record a wide diversity of environments, processes, and ages. Much work has been done to decipher potential mantle sources for Martian magmas and their interactions with crustal and surface environments. Chlorine isotopes provide a unique opportunity to assess interactions between Martian mantle-derived magmas and the crust. We have measured the Cl-isotopic composition of 17 samples that span the range of known ages, Martian environments, and mantle reservoirs. The 37Cl of the Martian mantle, as represented by the olivine-phyric <span class="hlt">shergottites</span>, NWA 2737 (chassignite), and Shergotty (basaltic <span class="hlt">shergottite</span>), has a low value of approximately -3.8‰. This value is lower than that of all other planetary bodies measured thus far. The Martian crust, as represented by regolith breccia NWA 7034, is variably enriched in the heavy isotope of Cl. This enrichment is reflective of preferential loss of 35Cl to space. Most basaltic <span class="hlt">shergottites</span> (less Shergotty), nakhlites, Chassigny, and Allan Hills 84001 lie on a continuum between the Martian mantle and crust. This intermediate range is explained by mechanical mixing through impact, fluid interaction, and assimilation-fractional crystallization.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20090043037','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20090043037"><span id="translatedtitle">Chlorine Abundances in Martian Meteorites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bogard, D.D.; Garrison, D.H.; Park, J.</p> <p>2009-01-01</p> <p>Chlorine measurements made in martian surface rocks by robotic spacecraft typically give Chlorine (Cl) abundances of approximately 0.1-0.8%. In contrast, Cl abundances in martian meteorites appear lower, although data is limited, and martian nakhlites were also subjected to Cl contamination by Mars surface brines. Chlorine abundances reported by one lab for whole rock (WR) samples of Shergotty, ALH77005, and EET79001 range 108-14 ppm, whereas Cl in nakhlites range 73-1900 ppm. Measurements of Cl in various martian weathering phases of nakhlites varied 0.04-4.7% and reveal significant concentration of Cl by martian brines Martian meteorites contain much lower Chlorine than those measured in martian surface rocks and give further confirmation that Cl in these surface rocks was introduced by brines and weathering. It has been argued that Cl is twice as effective as water in lowering the melting point and promoting melting at shallower martian depths, and that significant Cl in the <span class="hlt">shergottite</span> source region would negate any need for significant water. However, this conclusion was based on experiments that utilized Cl concentrations more analogous to martian surface rocks than to <span class="hlt">shergottite</span> meteorites, and may not be applicable to <span class="hlt">shergottites</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19940016412&hterms=Peridotite&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DPeridotite','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19940016412&hterms=Peridotite&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DPeridotite"><span id="translatedtitle">The carbon components in SNC meteorites of feldspathic harzburgite composition</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wright, I. P.; Douglas, C.; Pillinger, C. T.</p> <p>1993-01-01</p> <p>Two meteorites collected in Antarctica, ALH A77005 and LEW 88516, have characteristics which link them to the <span class="hlt">shergottite</span> group of SNC meteorites. Essentially, ALH A77005 and LEW 88516 are feldspathic harzburgites, being comprised of roughly equal quantities of olivine and pyroxene, with an additional few percent of feldspar which has subsequently been converted to maskelynite by shock. The meteorites represent samples of a cumulate rock which is itself composed of two different lithologies: in one, large pyroxenes poikilitically enclose olivine crystals, while the other consists of interstitial areas made up of pyroxene, olivine, maskelynite, whitlockite, troilite, ilmenite and chlorapatite. It has been proposed that meteorites such as ALH A77005 (and LEW 88516) are relict samples of the source peridotite from which the other <span class="hlt">shergottites</span> formed. As such it should be informative to study in detail the carbon components present within these samples, in order to make comparisons with data from other <span class="hlt">shergottites</span>. Although not plutonic in origin, and therefore not sampling a truly deep source, analyses of ALH A77005 and LEW 88516 should assist with attempts to define the bulk carbon isotopic composition of Mars. This has been assessed previously through analyses of carbon of presumed magmatic origin in other SNC meteorites, but the carbon isotopic compositions obtained seem to be at variance with what might be expected. It is important to constrain the carbon isotopic composition of Mars as well as possible so that models of atmospheric evolution, based on carbon isotopic data, can yield the most reliable results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1990Tectp.181..277K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1990Tectp.181..277K"><span id="translatedtitle">Geological structure, composition and evolution of crustal layers of the Japan Sea</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Karp, Boris Ya.; Lelikov, Eugene P.</p> <p>1990-09-01</p> <p>Seismic refraction data have shown that the crustal thickness in the Japan Sea basins (Japan Basin and <span class="hlt">Yamato</span> Basin) is 12-16 km, but the crustal thickness under the <span class="hlt">Yamato</span> Rise has not been determined, although it seems to be considerably larger. The crustal thickness in the Asian continental slope and shelf reaches 26 km. All crustal structure studied has a similar seismic layering: a sedimentary layer, a layer 2 (or intermediate layer) and a layer 3 (or the lower crustal layer). The velocities and ranges of velocity variations in the layers are almost similar. The greatest difference in crustal thickness is between layer 2 and layer 3. The thickness of layer 2 in the deep-sea basins is 1.5-5.3 km, beneath the <span class="hlt">Yamato</span> Rise it is 6.0-7.5 km and beneath the shelf and continental slope it is 9.8-11.7 km. The composition of layer 2 beneath the topographic highs and the continental slope has been studied by bottom sampling. Proterozoic to Paleogene granitic rocks and Archean-Proterozoic metamorphic rocks are the most common rock types. These rocks were formed at great and medium crustal depths, presumably in crust with a thickness of 30-40 km containing a layer 2 with a thickness of 10-15 km. The discrepancy between original and present crustal thickness suggests that the continental crust was thinned during the formation of the Japan Sea basin. Magmatic erosion of the intermediate layer during the ascent of mantle masses is proposed as a probable mechanism of this process. The result of this process could be a replacement of the sialic layer of the crust by basaltic rocks, which resulted in the formation of acid and alkahne melts erupted onto the surface during Oligocene-Early Miocene time.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.usgs.gov/of/1983/0172/report.pdf','USGSPUBS'); return false;" href="http://pubs.usgs.gov/of/1983/0172/report.pdf"><span id="translatedtitle">Garnet peridotites from Williams kimberlites, north-central Montana, U.S.A</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Hearn, B.C.; McGee, E.S.</p> <p>1983-01-01</p> <p>Two Williams kimberlites, 250x350m and 37x390m, in the eastern part of a swarm of 30 middle Eocene alnoitic diatremes in north-central Montana, USA, contain xenoliths of garnet-bearing <span class="hlt">lherzolites</span>, harzburgites and dunites, in addition to spinel peridotites and upper and lower crustal amphibolites and granulites. Colluvial purple, red, and pink garnets are dominantly Mg- and Cr-rich, indicating their derivation From peridotites or megacrysts, and have CaO and Cr2O3 contents that fall in the <span class="hlt">lherzolite</span> trend. Temperatures were calculated by the Lindsley-Dixon 20 kb method for <span class="hlt">lherzolites</span> and by the O'Neill-Wood method for harzburgites and dunites, and pressures were calculated by the MacGregor method, or were assumed to be 50 kb for dunites. Most peridotites equilibrated at 1220-1350?C and 50-60 kb, well above a 44mW/m2 shield geotherm and on or at higher P than the graphite-diamond boundary. Four <span class="hlt">lherzolites</span> are low T-P (830-990?C, 23-42 kb) and are close to the shield geotherm. All four low T-P <span class="hlt">lherzolites</span> have coarse textures whereas the high T-P cluster has both coarse and porphyroclastic textures, indicating a range of conditions of deformation and recrystallization in a restricted high T-P range. The tiny size (0.01-0.2 mm) of granulated and euhedral olivines in several xenoliths shows that deformation was occurring just prior to incorporation in kimberlite and that ascent was rapid enough (40-70 km/hr) to retard Further coarsening of fine-grained olivine. For other high T-P peridotites, cessation of deformation and beginning of recrystallization before or during inclusion in kimberlite is suggested by larger (up to 3mm) euhedral olivines in a matrix of fine granulated olivine or by optical continuity of large and nearby small olivines. Two low T-P <span class="hlt">lherzolites</span> contain distinctive, phlogopite-rimmed, 5-8mm clots of moderate-Cr garnet + Cr-spinel + Cr-diopside + enstatite that are inferred to have formed by reaction of an initial high-Cr garnet brought into the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.T21A4556C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.T21A4556C"><span id="translatedtitle">Lithospheric Mantle Contribution to High Topography in Central Mongolia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Carlson, R. W.; Ionov, D. A.</p> <p>2014-12-01</p> <p>Over 110 spinel peridotite xenoliths collected from four localities in the Tariat region, central Mongolia, show a predominance (over 90%) of fertile <span class="hlt">lherzolites</span> with subordinant harzburgite and peridotites veined with pyroxenite. Equilibration temperatures are high (~900°C at 1.5 GPa [1]). Major element compositions of the fertile samples are consistent with them being the residues of 0-6% partial melt removal at shallow depths [2]. The clinopyroxenes in the <span class="hlt">lherzolites</span> are moderately LREE depleted (average chondrite normalized La/Sm = 0.45) and most whole rocks show small, if any, depletions in Re and Pd compared to the other HSE. These data point to minimal metasomatic overprinting of these fertile <span class="hlt">lherzolites</span>. 187Os/188Os for samples with more than 3.2% Al2O3 range only from 0.126 to 0.131, within the range of modern fertile asthenospheric mantle. In contrast to the indicators of fertility in most samples, Sr, Nd and Hf isotopic composition of acid-leached clinopyroxene separates from the <span class="hlt">lherzolites</span> plot within the range of modern MORB with 87Sr/86Sr from 0.7021 to 0.7026, eNd from +7.7 to +9.8 and eHf from +13.3 to +18.5. The <span class="hlt">lherzolites</span> thus appear to sample a section of mantle that has compositional and isotope characteristics consistent with modern fertile asthenosphere. The isotopic composition of the Tariat <span class="hlt">lherzolites</span> are distinct from that of Cenozoic Mongolian basaltic volcanism pointing to limited involvement of the lithospheric mantle in magma generation in this area. The implied asthenospheric provenance of the mantle lithosphere suggests that it either could be the replacement for recently delaminated lithosphere or, more likely, a section of fertile mantle accreted to the base of the crust earlier, e.g. during construction of the Central Asian Orogenic Belt in the Mesozoic/Paleozoic. Although fertile, and hence compositionally dense, the high temperatures of the shallow lithospheric mantle under this section of Mongolia likely contribute to the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013GeCoA.115..241X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013GeCoA.115..241X"><span id="translatedtitle">Large magnesium isotope fractionation in peridotite xenoliths from eastern North China craton: Product of melt-rock interaction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xiao, Yan; Teng, Fang-Zhen; Zhang, Hong-Fu; Yang, Wei</p> <p>2013-08-01</p> <p>To investigate the effects of melt-rock interaction on Mg isotope fractionation and mantle Mg isotopic heterogeneity, we report high-precision Mg isotopic data of olivine (Ol), orthopyroxene (Opx), clinopyroxene (Cpx) and spinel (Spl) for 25 peridotite xenoliths from the eastern North China craton. These xenoliths range from <span class="hlt">lherzolites</span>, Cpx-rich <span class="hlt">lherzolites</span> to wehrlites, and are variably metasomatised. The <span class="hlt">lherzolites</span> have Ol with Fo contents from 89 to 90 and have a homogeneous Mg isotopic composition (δ26Mg = -0.26 to -0.20), similar to the typical mantle value. By contrast, Cpx-rich <span class="hlt">lherzolites</span> and wehrlites have lower Ol with Fo contents (78-88) and exhibit larger Mg isotopic variations, with δ26Mg ranging from -0.39 to +0.09. The δ26Mg values of minerals in these xenoliths are also variable and range from -0.45 to -0.03 in Ol, from -0.26 to -0.01 in Opx, from -0.34 to +0.22 in Cpx and from -0.16 to +0.25 in Spl. Inter-mineral fractionations between coexisting pyroxene and Ol in <span class="hlt">lherzolites</span> and most isotopically light wehrlites (Δ26MgOpx-Ol = -0.04 to +0.09‰; Δ26MgCpx-Ol = + 0.02 to +0.25‰) vary as a function of temperature and are consistent with equilibrium inter-mineral isotope fractionations. By contrast, large disequilibrium Mg isotope fractionation occurs between coexisting pyroxene and Ol in the majority of Cpx-rich <span class="hlt">lherzolites</span> (Δ26MgOpx-Ol = +0.16 to +0.32‰; Δ26MgCpx-Ol = +0.04 to +0.34‰). Both types of isotope fractionations also occur between Spl and Ol, with Spl being consistently heavier than Ol (Δ26MgSpl-Ol = +0.15 to +0.55‰). Overall, the isotopically equilibrated but light wehrlites may result from mantle metasomatism by isotopically light melt, whereas large disequilibrium isotope fractionations in Cpx-rich peridotites likely reflect kinetic isotope fractionation during melt-peridotite interaction. Both processes result in the heterogeneous Mg isotopic composition of the lithospheric mantle beneath the eastern North China</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016E%26PSL.438...57X&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016E%26PSL.438...57X&link_type=ABSTRACT"><span id="translatedtitle">Southward trench migration at ∼130-120 Ma caused accretion of the Neo-Tethyan forearc lithosphere in Tibetan ophiolites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xiong, Qing; Griffin, William L.; Zheng, Jian-Ping; O'Reilly, Suzanne Y.; Pearson, Norman J.; Xu, Bo; Belousova, Elena A.</p> <p>2016-03-01</p> <p>The preservation of ultrahigh-pressure and super-reduced phases (diamond, moissanite, etc.) in the harzburgites and chromitites of the Yarlung Zangbo ophiolites (South Tibet, China) has major implications for mantle recycling and lithosphere evolution in the tectonic system related to the closing of the Neo-Tethyan Ocean. However, important aspects of the genesis of these enigmatic ophiolites and the related geodynamic evolution are still unclear. In the Zedang ophiolite of the eastern Yarlung Zangbo Suture, detailed mineral chemical data reveal that the harzburgite domain in the east [spinel Cr# (mole Cr3+/(Cr3+ + Al3+) = 0.62-0.33] is more depleted than the <span class="hlt">lherzolite</span> domain in the west (spinel Cr# = 0.30-0.17) and shows much lower equilibration temperatures (by ∼250-150 °C) than the <span class="hlt">lherzolites</span>. Clinopyroxene trace-element compositions indicate that the harzburgites underwent pervasive metasomatism after melt extraction, while the <span class="hlt">lherzolites</span> did not. New zircon U-Pb ages show that the harzburgites were intruded by dolerite dykes with chilled margins at ∼130-128 Ma, consistent with the widespread mafic magmatism at ∼130-120 Ma in the Yarlung Zangbo ophiolites. Nd-Hf isotopic data indicate that the Zedang <span class="hlt">lherzolites</span> subcreted the pre-emplaced harzburgites concurrently with the intrusion of the dolerite dykes into the harzburgites, and that the <span class="hlt">lherzolites</span> and dolerites both were derived from upwelling asthenosphere with minor slab input. Available zircon geochronology and Hf-isotope data show that juvenile magmatism in the adjacent Gangdese Arc was almost completely interrupted from ∼130-120 Ma. We suggest that the extension of the overlying harzburgitic lithosphere, subcretion of <span class="hlt">lherzolites</span>, intrusion of mafic dykes, and the waning of Gangdese-Arc magmatism all reflect a southward trench migration in the Neo-Tethyan subduction system from the Gangdese Arc to the oceanic forearc lithosphere. This magmatic relocation and tectonic linkage are inferred to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19860019355','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19860019355"><span id="translatedtitle">Terrestrial ages of Antarctic meteorites: Implications for concentration mechanisms</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Schultz, L.</p> <p>1986-01-01</p> <p>Antarctic meteorites differ from meteorites fallen in other places in their mean terrestrial ages. Boeckl estimated the terrestrial half-life for the disintegration of stone meteorites by weathering under the climatic conditions of the Western United States to be about 3600 years. Antarctic meteorites, however, have terrestrial ages up to 70000 years, indicating larger weathering half-lives. The terrestrial ages of meteorites are determined by their concentration of cosmic-ray-produced radionuclides with suitable half-lives (C-14, Al-26, and Cl-36). These radionuclides have yielded reliable ages for the Antarctic meteorites. The distribution of terrestrial ages of Allan Hills and <span class="hlt">Yamato</span> meteorites are examined.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012Icar..221.1183F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012Icar..221.1183F"><span id="translatedtitle">Impact ejection of lunar meteorites and the age of Giordano Bruno</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fritz, Jörg</p> <p>2012-11-01</p> <p>Based on literature data from lunar meteorites and orbital observations it is argued that the lunar crater Giordano Bruno (22 km ∅) formed more than 1 Ma ago and probably ejected the lunar meteorites <span class="hlt">Yamato</span> 82192/82193/86032 at 8.5 ± 1.5 Ma ago from the Th-poor highlands of the Moon. The efficiency and time scale to deliver 3He-rich lunar material into Earth’s sediments is discussed to assess the temporal relationship between the Giordano Bruno cratering event and a 1 Ma enduring 3He-spike which is observed in 8.2 Ma old sediments on Earth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050182075','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050182075"><span id="translatedtitle">Petrography of Lunar Meteorite MET 01210, A New Basaltic Regolith Breccia</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zeigler, R. A.; Korotev, R. L.; Jolliff, B. L.; Haskin, L. A.</p> <p>2005-01-01</p> <p>Lunar meteorite MET 01210 (hereafter referred to as MET) is a 22.8 g breccia collected during the 2001 field season in the Meteorite Hills, Antarctica. Although initially classified as an anorthositic breccia, MET is a regolith breccia composed predominantly of very-low-Ti (VLT) basaltic material. Four other brecciated lunar meteorites (NWA 773, QUE 94281, EET 87/96, <span class="hlt">Yamato</span> 79/98) with a significant VLT basaltic component have been identified. We present here the petrography and bulk major element composition of MET and compare it to previously studied basaltic lunar meteorite breccias.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19830034111&hterms=cmas&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dcmas%2Br','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19830034111&hterms=cmas&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dcmas%2Br"><span id="translatedtitle">Theoretical prediction of phase relationships in planetary mantles</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wood, B. J.; Holloway, J. R.</p> <p>1982-01-01</p> <p>Thermodynamic and phase equilibrium data are used to generate an internally consistent set of enthalpies and entropies for important components of the CaO-MgO-Al2O3-SiO2 (CMAS) system in silica-undersaturated compositions. The addition of Na and Fe(2+) to the CMAS system produces shifts in the plagioclase, spinel and garnet stability fields. While the Morgan and Anders (1979) model Martian composition has stability fields of plagioclase and garnet <span class="hlt">lherzolite</span>, and a small spinel <span class="hlt">lherzolite</span> field at temperatures below 900 C, the Martian mantle composition of McGetchin and Smyth (1978) would not contain orthopyroxene, and a low pressure assemblage of plagioclase-spinel wehrlite would be replaced by garnet-spinel wehrlite at higher pressure. In both cases, the Fe-Mg ratio would be substantially greater than that found in primitive terrestrial basalts.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012Litho.150..171L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012Litho.150..171L"><span id="translatedtitle">The Xinchang peridotite xenoliths reveal mantle replacement and accretion in southeastern China</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, Chuan-Zhou; Wu, Fu-Yuan; Sun, Jing; Chu, Zhu-Yin; Qiu, Zhi-Li</p> <p>2012-10-01</p> <p>The Xinchang mantle xenoliths, including garnet <span class="hlt">lherzolites</span>, spinel <span class="hlt">lherzolites</span> and harzburgites, have been studied for the nature and age of the lithospheric mantle beneath southeastern (SE) China. The spinel harzburgites have refractory compositions, with 0.95-1.73 wt.% Al2O3, 0.65-1.47 wt.% CaO, 0.03-0.16 wt.% TiO2 and 2134-2422 ppm Ni. The <span class="hlt">lherzolites</span> (both spinel- and garnet-) have more fertile compositions, containing 2.4-5.43 wt.% Al2O3, 2.17-3.22 wt.% CaO, 0.1-0.38 wt.% TiO2 and 1733-2055 ppm Ni. Olivines in the harzburgites have Fo contents of 88.7-91.4, which is 88.4-90.2 for the <span class="hlt">lherzolites</span>. Both clinopyroxene and orthopyroxene have lower Al2O3 but higher Cr2O3 contents than those in the <span class="hlt">lherzolites</span>. Modeling of the Y and Yb contents in clinopyroxenes indicates that the spinel harzburgites have been subjected to ca. 20% degrees of partial melting. Reaction textures, in particular the sieve-texture in clinopyroxene, is widely developed in the Xinchang mantle xenoliths, which resulted from reaction with the host lavas. The sieve-textured clinopyroxenes show compositional zonation; the sieve-textured rims have lower Na2O and Al2O3 but higher Cr2O3 and CaO than the inclusion-free cores. The inclusion-free cores of clinopyroxene in the harzburgites show clearly enriched characteristics in trace elements, reflecting they have been metasomatized before the entrainment in the host lavas. Clinopyroxenes have high Ti/Eu but low La/Ya ratios, suggesting that the Xinchang mantle xenoliths were metasomatized by silicate melts. The spinel harzburgites have 187Os/188Os of 0.11999-0.12258, giving TRD age of 0.99-1.35 Ga relative to the primitive upper mantle (PUM). In comparison, both spinel and garnet <span class="hlt">lherzolites</span> have more radiogenic 187Os/188Os ratios (0.12424-0.12801) and younger model ages (0.22-0.75 Ga). We explain that the spinel harzburgites represent the ancient lithosphere relic beneath the Xinchang region, whereas both spinel and garnet <span class="hlt">lherzolites</span> represent</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002CRGeo.334..387Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002CRGeo.334..387Z"><span id="translatedtitle">Les xénolites ultramafiques du volcanisme alcalin quaternaire d'Oranie (Tell, Algérie occidentale), témoins d'une lithosphère cisaillée et enrichieUltramafic xenoliths from Quaternary alkali volcanism from Oranie (Tell, western Algeria): witnesses of a sheared and enriched lithosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zerka, Mohamed; Cottin, Jean-Yves; Grégoire, Michel; Lorand, Jean-Pierre; Megartsi, M'Hamed; Midoun, Mohamed</p> <p></p> <p>Numerous ultramafic xenoliths occur within the Aı̈n-Temouchent volcanic complex (Northwestern Oranie, Algeria). Most of them are type I mantle tectonites (<span class="hlt">lherzolites</span> and harzburgites) and composite xenoliths (harzburgite/clinopyroxenite) are rare. Only a few samples of spinel <span class="hlt">lherzolites</span> display relatively fertile compositions when the major part of type I xenoliths have refractory major element compositions but enriched LREE contents showing that they have been affected by mantle metasomatism. The composite xenoliths are witnesses of reactions of alkaline magmas with the upper mantle. An asthenospheric rising, in relation with the large strike slip fault affecting the North African plate margin at Trias time is proposed as a possible geodynamical setting. To cite this article: M. Zerka et al., C. R. Geoscience 334 (2002) 387-394.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..15.5541B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15.5541B"><span id="translatedtitle">A Dynamic study of Mantle processes applying In-situ Methods to Compound Xenoliths: implications for small to intermediate scale heterogeneity</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Baziotis, Ioannis; Asimow, Paul; Koroneos, Antonios; Ntaflos, Theodoros; Poli, Giampero</p> <p>2013-04-01</p> <p>The mantle is the major geochemical reservoir of most rock-forming elements in the Earth. Convection and plate-tectonic driven processes act to generate local and regional heterogeneity within the mantle, which in turn through thermal and chemical interactions modulates ongoing geophysical processes; this feedback shapes the dynamics of the deep interior. Consequently, these processes contribute to the evolution of the earth throughout its geological history. Up to now, the heterogeneity of the mantle has been extensively studied in terms of conventional methods using basalt chemistry, bulk rock and mineral major and trace element analysis of isolated xenolith specimens of varying lithology, and massif exposures. The milestone of the present study, part of an ongoing research project, is the application of in-situ analytical methods such as microprobe, LA-ICP-MS and high resolution SEM in order to provide high quality major and trace element analyses as well as elemental distribution of the coexisting phases in the preserved intra-mantle lithologies, Particularly, in the context of the current study we used selected compound xenoliths from San Carlos (Arizona, USA), Kilbourne Hole (New Mexico, USA), Cima Dome and Dish Hill suites (California, USA), San Quintin (Baja California, Mexico) and Chino Valley (Arizona, USA), from the Howard Wilshire collection archived at the Smithsonian Institution. The selection of these compound xenoliths was based upon freshness and integrity of specimens, maximum distance on both sides of lithologic contacts, and rock types thought most likely to represent subsolidus juxtaposition of different lithologies that later partially melted in contact. The San Carlos samples comprise composite xenoliths with websterite, <span class="hlt">lherzolite</span> and clinopyroxenite layers or clinopyroxenite veins surrounded by <span class="hlt">lherzolite</span> or orthopyroxenite-rich rims. The Kilbourne Hole suite comprises spinel-(olivine) clinopyroxenite and orthopyroxenite dikes cutting</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/17831161','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/17831161"><span id="translatedtitle">Diamonds in an upper mantle peridotite nodule from kimberlite in southern wyoming.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>McCallum, M E; Eggler, D H</p> <p>1976-04-16</p> <p>Diamonds in a serpentinized garnet peridotite nodule from a diatreme in southern Wyoming are the first known occurrence in an upper mantle peridotite xenolith from a kimberlite intrusion in North America as well as the second authenticated occurrence of diamonds from kimberlite pipes in North America. The nodule is believed to have come from a section of depleted (partially melted) <span class="hlt">lherzolite</span> at a depth of 130 to 180 kilometers. PMID:17831161</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150019464','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150019464"><span id="translatedtitle">Water in the Lithospheric Mantle Beneath a Phanerozoic Continental Belt: FTIR Analyses of Alligator Lake Xenoliths (Yukon, Canada)</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gelber, McKensie; Peslier, Ann H.; Brandon, Alan D.</p> <p>2015-01-01</p> <p>Water in the mantle influences melting, metasomatism, viscosity and electrical conductivity. The Alligator Lake mantle xenolith suite is one of three bimodal peridotite suites from the northern Canadian Cordillera brought to the surface by alkali basalts, i.e., it consists of chemically distinct <span class="hlt">lherzolites</span> and harzburgites. The <span class="hlt">lherzolites</span> have equilibration temperatures about 50 C lower than the harzburgites and are thought to represent the fertile upper mantle of the region. The harzburgites might have come from slightly deeper in the mantle and/or be the result of a melting event above an asthenospheric upwelling detected as a seismic anomaly at 400-500 km depth. Major and trace element data are best interpreted as the <span class="hlt">lherzolite</span> mantle having simultaneously experienced 20-25% partial melting and a metasomatic event to create the harzburgites. Well-characterized xenoliths are being analyzed for water by FTIR. Harzburgites contain 29-52 ppm H2O in orthopyroxene (opx) and (is) approximately140 ppm H2O in clinopyroxene (cpx). The <span class="hlt">lherzolites</span> have H2O contents of 27-150 ppm in opx and 46-361 ppm in cpx. Despite correlating with enrichments in LREE, the water contents of the harzburgite pyroxenes are low relative to those of typical peridotite xenoliths, suggesting that the metasomatic agents were water-poor, contrarily to what has been suggested before. The water content of cpx is about double that of opx indicating equilibrium. Olivine water contents are low ((is) less than 5 ppm H2O) and out of equilibrium with those of opx and cpx, which may be due to H loss during xenolith ascent. This is consistent with olivines containing more water in their cores than their rims. Olivines exclusively exhibit water bands in the 3400-3000 cm-1 range, which may be indicative of a reduced environment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EP%26S...66...46J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EP%26S...66...46J"><span id="translatedtitle">Characterization of olivine fabrics and mylonite in the presence of fluid and implications for seismic anisotropy and shear localization</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jung, Sejin; Jung, Haemyeong; Austrheim, Håkon</p> <p>2014-12-01</p> <p>The Lindås Nappe, Bergen Arc, is located in western Norway and displays two high-grade metamorphic structures. A Precambrian granulite facies foliation is transected by Caledonian fluid-induced eclogite-facies shear zones and pseudotachylytes. To understand how a superimposed tectonic event may influence olivine fabric and change seismic anisotropy, two lenses of spinel <span class="hlt">lherzolite</span> were studied by scanning electron microscope (SEM) and electron back-scattered diffraction (EBSD) techniques. The granulite foliation of the surrounding anorthosite complex is displayed in ultramafic lenses as a modal variation in olivine, pyroxenes, and spinel, and the Caledonian eclogite-facies structure in the surrounding anorthosite gabbro is represented by thin (<1 cm) garnet-bearing ultramylonite zones. The olivine fabrics in the spinel bearing assemblage were E-type and B-type and a combination of A- and B-type lattice preferred orientations (LPOs). There was a change in olivine fabric from a combination of A- and B-type LPOs in the spinel bearing assemblage to B- and E-type LPOs in the garnet <span class="hlt">lherzolite</span> mylonite zones. Fourier transform infrared (FTIR) spectroscopy analyses reveal that the water content of olivine in mylonite is much higher (approximately 600 ppm H/Si) than that in spinel <span class="hlt">lherzolite</span> (approximately 350 ppm H/Si), indicating that water caused the difference in olivine fabric. Fabric strength of olivine gets weaker as the grain size reduced, and as a result, calculated seismic properties for the two deformation stages reveal that P- and S-velocity anisotropies are significantly weaker in the mylonite. Microtextures and LPO data indicate that the deformation mechanism changed from dominant dislocation creep in spinel <span class="hlt">lherzolite</span> to dislocation creep accompanied by grain-boundary sliding in mylonite. Shear localization in the mylonite appears to be originated from the grain size reduction through (1) enhanced dynamic recrystallization of olivine in the presence of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1988CoMP..100..261V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1988CoMP..100..261V"><span id="translatedtitle">Isotopic constraints on the origin of ultramafic and mafic dikes in the Balmuccia peridotite (Ivrea Zone)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Voshage, H.; Sinigoi, S.; Mazzucchelli, M.; Demarchi, G.; Rivalenti, G.; Hofmann, A. W.</p> <p>1988-11-01</p> <p>The Balmuccia peridotite massif in the central Ivrea Zone constitutes an upper mantle slice which has been tectonically emplaced into the crust. It represents the residue from partial melting of undepleted mantle material and varies in composition from <span class="hlt">lherzolite</span> to harzburgite and subordinate dunite. Dikes of websterite and gabbroic pods within the peridotite can be subdivided into an older Crdiopside suite and a younger Al-augite suite. Nd isotopic data on whole rocks of these lithotypes in combination with independent observations suggest that the dikes formed during a Hercynian event about 270 Ma ago. The rocks of the Cr-diopside dikes, in particular, display isotopic signatures similar to those of the <span class="hlt">lherzolite</span> and represent fractionates from partial melts derived from the <span class="hlt">lherzolite</span> wall rock. The Sm-Nd data of the pyroxenites and gabbros of the Al-augite suite, in contrast, scatter widely and suggest that partial melting of <span class="hlt">lherzolite</span> was triggered or at least accompanied by introduction of fluids and/or liquid phases. These fluids or liquids carried exotic isotopic components from elsewhere in the crust-mantle complex, and deposited them within the rocks by metasomatic reactions. Two distinct types of metasomatism must have operated not only within the Balmuccia body, but also in the complex of Finero: The first type of metasomatism introduced mantle-derived volatiles and is responsible for formation of amphibole. The other type has a crustal source and led to formation of phlogopite, which occurs mainly within mantle rocks of Finero, but occasionally, within the Balmuccia body also.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1811144M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1811144M"><span id="translatedtitle">Geochemical record of subduction initiation in the sub-arc mantle: insights from Loma Caribe peridotite (Dominican Republic)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Marchesi, Claudio; Garrido, Carlos J.; Proenza, Joaquín A.; Hidas, Károly; Varas-Reus, María Isabel; Butjosa, Lidia; Lewis, John F.</p> <p>2016-04-01</p> <p>The Loma Caribe peridotite body is mainly composed of serpentinized spinel harzburgite and <span class="hlt">lherzolite</span> and minor (Opx-bearing) dunite. Modal proportions, mineral and whole-rock major and trace element compositions generally coincide with those of abyssal mantle rocks from mid-ocean ridges for <span class="hlt">lherzolite</span> and refractory supra-subduction peridotites for harzburgite and (Opx-) dunite. Cpx-bearing harzburgite has intermediate compositions that overlap those of residual mantle from both these settings. Major elements in peridotite were mostly undisturbed by serpentinization and/or seafloor weathering whereas LREE and LILE were enriched by syn- and/or post-melting interaction with fluids/melts. Major element variations support that protoliths of Loma Caribe peridotite mostly melted at 1-2 GPa and 1300-1500 °C, as normal mid-ocean ridge and supra-subduction zone mantle. MREE/HREE fractionations in whole-rocks and clinopyroxene can be explained by initial low (5-6%) fractional melting of a garnet <span class="hlt">lherzolite</span> source followed by variable (5-20%) melting in the spinel stability field. <span class="hlt">Lherzolite</span> and Cpx-harzburgite are residues of increasing melting triggered by increasing addition of fluids to a spinel peridotite source, while melting of the harzburgite protolith was likely promoted by focused flux of hydrous melts. Dunite and Opx-bearing dunite are products of pyroxene dissolution in residual peridotite caused by reaction with two different subduction-related melts, likely the parental magmas of Early Cretaceous low-Ti IAT and boninite from Central Hispaniola, respectively. We propose that the geochemical heterogeneity of Loma Caribe peridotite records shifting conditions of melting during the development of subduction beneath the incipient Greater Antilles paleo-island arc in the Early Cretaceous. The common presence in the Caribbean realm of oceanic mantle rocks related to subduction indicates that most peri-Caribbean ophiolitic bodies are not fragments of an oceanic</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19800039413&hterms=Dunite&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DDunite','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19800039413&hterms=Dunite&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DDunite"><span id="translatedtitle">A summary of the petrology and geochemistry of pristine highlands rocks</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Norman, M. D.; Ryder, G.</p> <p>1979-01-01</p> <p>The petrology and geochemistry of pristine lunar highlands rock samples consisting of ferroan anorthosites, norites, troctolites, spinel troctolites/dunite/<span class="hlt">lherzolite</span>, and KREEP, are described. In addition, petrographic and chemical evidence is presented which shows that low-siderophile rocks are the result of endogenous igneous activity and not impact melt differentiation. For example, these rocks contain Fe-metal as a late-crystallizing phase, and have W/La ratios higher than polymict breccias.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012CoMP..164..441T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012CoMP..164..441T"><span id="translatedtitle">Carbonate-rich melt infiltration in peridotite xenoliths from the Eurasian-North American modern plate boundary (Chersky Range, Yakutia)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tschegg, Cornelius; Ntaflos, Theodoros; Akinin, Vyacheslav V.; Hauzenberger, Christoph</p> <p>2012-09-01</p> <p>A suite of mainly spinel peridotite and subordinate pyroxenite xenoliths and megacrysts were studied in detail, enabling us to characterize upper mantle conditions and processes beneath the modern North American-Eurasian continental plate boundary. The samples were collected from 37-Ma-old basanites cropping out in the Main Collision Belt of the Chersky Range, Yakutia Republic (Russian Far East). The spinel <span class="hlt">lherzolites</span> reflect a mantle sequence, equilibrated at temperatures of 890-1,025 °C at pressures of 1.1-2 GPa, with melt extraction estimated to be around 2-6 %. The spinel harzburgites are characterized by lower P-T equilibration conditions and estimated melt extraction up to 12 %. Minor cryptic metasomatic processes are recorded in the clinopyroxene trace elements, revealing that percolating hydrous fluid-rich melts and basaltic melts affected the peridotites. One of the <span class="hlt">lherzolites</span> preserves a unique melt droplet with primary dolomite in perfect phase contact with Na-rich aluminosilicate glass and sodalite. On the basis of the well-constrained P-T frame of the xenolith suite, as well as the rigorously documented melt extraction and metasomatic history of this upper mantle section, we discuss how a carbonated silicate melt infiltrated the <span class="hlt">lherzolite</span> at depth and differentiated into an immiscible carbonate and silicate liquid shortly before the xenolith was transported to the surface by the host basalt. Decreasing temperatures triggered crystallization of primary dolomite from the carbonate melt fraction and sodalite as well as quenched glass from the Na-rich aluminosilicate melt fraction. Rapid entrainment and transport to the Earth's surface prevented decarbonatization processes as well as reaction phenomena with the host <span class="hlt">lherzolite</span>, preserving this exceptional snapshot of upper mantle carbonatization and liquid immiscibility.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016Litho.252....1M&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016Litho.252....1M&link_type=ABSTRACT"><span id="translatedtitle">Geochemical record of subduction initiation in the sub-arc mantle: Insights from the Loma Caribe peridotite (Dominican Republic)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Marchesi, Claudio; Garrido, Carlos J.; Proenza, Joaquín A.; Hidas, Károly; Varas-Reus, María Isabel; Butjosa, Lidia; Lewis, John F.</p> <p>2016-05-01</p> <p>The Loma Caribe peridotite body is mainly composed of serpentinized spinel harzburgites and <span class="hlt">lherzolites</span> and minor orthopyroxene-bearing dunites and dunites. Modal proportions, mineral and whole-rock major and trace element compositions generally coincide with those of abyssal mantle rocks from mid-ocean ridges for the <span class="hlt">lherzolites</span>, and refractory supra-subduction peridotites for the harzburgites and dunites. The clinopyroxene-bearing harzburgites have intermediate compositions that overlap with those of residual mantle from both these settings. Major elements in the peridotites were mostly undisturbed by serpentinization and/or seafloor weathering whereas light rare earth elements (LREE) and large ion lithophile elements (LILE) were enriched by syn- and/or post-melting interaction with fluids/melts. Major element variations indicate that protoliths of the Loma Caribe peridotites mostly melted at 1-2 GPa and 1250 °C-1500 °C, as normal mid-ocean ridge and supra-subduction zone mantle. The MREE/HREE fractionations in both whole rocks and clinopyroxene can be explained by initial low (5%-6%) fractional melting of a garnet <span class="hlt">lherzolite</span> source followed by variable (5%-20%) melting in the spinel stability field. The <span class="hlt">lherzolites</span> and clinopyroxene-bearing harzburgites are residues of increasing melting triggered by increasing addition of slab fluids to a spinel peridotite source, while melting of the harzburgite protoliths was likely the result of focused flux of slab hydrous melts. The dunites and orthopyroxene-bearing dunites are products of pyroxene dissolution in residual peridotites caused by reaction with two different subduction-related melts, probably the parental magmas of Early Cretaceous low-Ti island arc tholeiites (IAT) and boninites from Central Hispaniola, respectively. We conclude that the geochemical heterogeneity of the Loma Caribe peridotites records shifting conditions of melting during the development of subduction beneath the incipient Greater Antilles</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/10102809','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/10102809"><span id="translatedtitle">Clinoenstatite in alpe arami peridotite: additional evidence of very high pressure</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bozhilov; Green; Dobrzhinetskaya</p> <p>1999-04-01</p> <p>Observations by transmission electron microscopy show that lamellae of clinoenstatite are present in diopside grains of the Alpe Arami garnet <span class="hlt">lherzolite</span> of the Swiss Alps. The simplest interpretation of the orientation, crystallography, and microstructures of the lamellae and the phase relationships in this system is that the lamellae originally exsolved as the high-pressure C-centered form of clinoenstatite. These results imply that the rocks were exhumed from a minimum depth of 250 kilometers before or during continental collision. PMID:10102809</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015EGUGA..17.4941J&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015EGUGA..17.4941J&link_type=ABSTRACT"><span id="translatedtitle">Characterization of olivine fabrics and mylonite in the presence of fluid and implications for seismic anisotropy and shear localization</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jung, Sejin; Jung, Haemyeong; Austrheim, Håkon</p> <p>2015-04-01</p> <p>The Lindås Nappe, Bergen Arc, is located in western Norway and displays two high-grade metamorphic structures. A Precambrian granulite facies foliation is transected by Caledonian fluid-induced eclogite-facies shear zones and pseudotachylytes. To understand how a superimposed tectonic event may influence olivine fabric and change seismic anisotropy, two lenses of spinel <span class="hlt">lherzolite</span> were studied by SEM and EBSD techniques. The granulite foliation of the surrounding anorthosite complex is displayed in ultramafic lenses as a modal variation in olivine, pyroxenes and spinel, and the Caledonian eclogite-facies structure in the surrounding anorthosite gabbro is represented by thin (<1 cm) garnet-bearing ultramylonite zones. The olivine fabrics in the spinel bearing assemblage were E-type and B-type and a combination of A- and B-type LPOs. There was a change in olivine fabric from a combination of A- and B-type LPOs in the spinel bearing assemblage to B- and E-type LPOs in the garnet <span class="hlt">lherzolite</span> mylonite zones. FTIR analyses reveal that the water content of olivine in mylonite is much higher (~600 ppm H/Si) than that in spinel <span class="hlt">lherzolite</span> (~350 ppm H/Si), indicating that water caused the difference in olivine fabric. Fabric strength of olivine gets weaker as the grain size reduced, and as a result calculated seismic properties for the two deformation stages reveal that P- and S-velocity anisotropies are significantly weaker in the mylonite. Microtextures and LPO data indicate that the deformation mechanism changed from dominant dislocation creep in spinel <span class="hlt">lherzolite</span> to dislocation creep accompanied by grain-boundary sliding in mylonite. Shear localization in the mylonite appears to be originated from the grain size reduction through (1) enhanced dynamic recrystallization of olivine in the presence of water and (2) Zener pinning of clinopyroxene, or (3) by ultracommunition during the pseudotachylyte stage.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5870369','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5870369"><span id="translatedtitle">Mantle metasomatism</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Menzies, M.; Hawkesworth, C.</p> <p>1986-01-01</p> <p>The concept of metasomatism and its role in the geochemical enrichment and depletion processes in upper mantle rocks remains contentious. This volume makes a comprehensive contribution to the study of metasomatic and enrichment processes: origin and importance in determining trace element and isotopic heterogeneity in the lithospheric mantle. It begins with a theoretical thermodynamic and experimental justification for metasomatism and proceeds to present evidence for this process from the study of mantle xenoliths. Finally the importance of metasomatism in relation to basaltic volcanism is assessed. The contents are as follows: Dynamics of Translithospheric Migration of Metasomatic Fluid and Alkaline Magma. Solubility of Major and Trace Elements in Mantle Metasomatic Fluids: Experimental Constraints. Mineralogic and Geochemical Evidence for Differing Styles of Metasomatism in Spinel <span class="hlt">Lherzolite</span> Xenoliths: Enriched Mantle Source Regions of Basalts. Characterization of Mantle Metasomatic Fluids in Spinel <span class="hlt">Lherzolites</span> and Alkali Clinophyroyxenites from the West Eifel and South-West Uganda. Metasomatised Harzburgites in Kimberlite and Alkaline Magmas: Enriched Resites and ''Flushed'' <span class="hlt">Lherzolites</span>. Metasomatic and Enrichment Phenomena in Garnet-Peridotite Facies Mantle Xenoliths from the Matsoku Kimberlite Pipe Lesotho. Evidence for Mantle Metasomatism in Periodite Nodules from the Kimberley Pipes South Africa. Metasomatic and Enrichment Processes in Lithospheric Peridotites, an Effective of Asthenosphere-Lithosphere Interaction. Isotope Variations in Recent Volcanics: A Trace Element Perspective. Source Regions of Mid-Ocean Ridge Basalts: Evidence for Enrichment Processes. The Mantle Source for the Hawaiian Islands: Constraints from the Lavas and Ultramafic Inclusions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015E%26PSL.417..164W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015E%26PSL.417..164W"><span id="translatedtitle">Comment on "A non-primitive origin of near-chondritic Ssbnd Sesbnd Te ratios in mantle peridotites: Implications for the Earth's late accretionary history" by König S. et al. [Earth Planet. Sci. Lett. 385 (2014) 110-121</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Zaicong; Becker, Harry</p> <p>2015-05-01</p> <p>The abundances and ratios of S, Se and Te in rocks from the Earth's mantle may yield valuable constraints on the partitioning of these chalcophile elements between the mantle and basaltic magmas and on the compositions of these elements in the primitive mantle (PM) (e.g. Wang and Becker, 2013). Recently, König et al. (2014) proposed a model in which the CI chondrite-like Se/Te of mantle <span class="hlt">lherzolites</span> (Se /Te = 8 ± 2, 1σ) are explained by mixing of sulfide melts with low Se/Te with harzburgites containing supposedly residual sulfides with high Se/Te. In this model sulfide melts and platinum group element (PGE) rich telluride phases with low Se/Te are assumed to have precipitated during refertilization of harzburgites by basic melts to form <span class="hlt">lherzolites</span>. Because of the secondary nature of these re-enrichment processes, the authors state that abundances and ratios of S, Se and Te in fertile <span class="hlt">lherzolites</span> cannot reflect the composition of the PM.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015JAfES.111...26N&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015JAfES.111...26N&link_type=ABSTRACT"><span id="translatedtitle">Sub-continental lithospheric mantle structure beneath the Adamawa plateau inferred from the petrology of ultramafic xenoliths from Ngaoundéré (Adamawa plateau, Cameroon, Central Africa)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nkouandou, Oumarou F.; Bardintzeff, Jacques-Marie; Fagny, Aminatou M.</p> <p>2015-11-01</p> <p>Ultramafic xenoliths (<span class="hlt">lherzolite</span>, harzburgite and olivine websterite) have been discovered in basanites close to Ngaoundéré in Adamawa plateau. Xenoliths exhibit protogranular texture (<span class="hlt">lherzolite</span> and olivine websterite) or porphyroclastic texture (harzburgite). They are composed of olivine Fo89-90, orthopyroxene, clinopyroxene and spinel. According to geothermometers, <span class="hlt">lherzolites</span> have been equilibrated at 880-1060 °C; equilibrium temperatures of harzburgite are rather higher (880-1160 °C), while those of olivine websterite are bracketed between 820 and 1010 °C. The corresponding pressures are 1.8-1.9 GPa, 0.8-1.0 GPa and 1.9-2.5 GPa, respectively, which suggests that xenoliths have been sampled respectively at depths of 59-63 km, 26-33 km and 63-83 km. Texture and chemical compositional variations of xenoliths with temperature, pressure and depth on regional scale may be ascribed to the complex history undergone by the sub-continental mantle beneath the Adamawa plateau during its evolution. This may involve a limited asthenosphere uprise, concomitantly with plastic deformation and partial melting due to adiabatic decompression processes. Chemical compositional heterogeneities are also proposed in the sub-continental lithospheric mantle under the Adamawa plateau, as previously suggested for the whole Cameroon Volcanic Line.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70015625','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70015625"><span id="translatedtitle">DUPAL anomaly in the Sea of Japan: Pb, Nd, and Sr isotopic variations at the eastern Eurasian continental margin</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Tatsumoto, M.; Nakamura, Y.</p> <p>1991-01-01</p> <p>Volcanic rocks from the eastern Eurasian plate margin (southwestern Japan, the Sea of Japan, and northeastern China) show enriched (EMI) component signatures. Volcanic rocks from the Ulreung and Dog Islands in the Sea of Japan show typical DUPAL anomaly characteristics with extremely high ??208/204 Pb (up to 143) and enriched Nd and Sr isotopic compositions (??{lunate}Nd = -3 to -5, 87Sr 86Sr = ~0.705). The ??208/204 Pb values are similar to those associated with the DUPAL anomaly (up to 140) in the southern hemisphere. Because the EMI characteristics of basalts from the Sea of Japan are more extreme than those of southwestern Japan and inland China basalts, we propose that old mantle lithosphere was metasomatized early (prior to the Proterozoic) with subduction-related fluids (not present subduction system) so that it has been slightly enriched in incompatible elements and has had a high Th/U for a long time. The results of this study support the idea that the old subcontinental mantle lithosphere is the source for EMI of oceanic basalts, and that EMI does not need to be stored at the core/ mantle boundary layer for a long time. Dredged samples from seamounts and knolls from the <span class="hlt">Yamato</span> Basin Ridge in the Sea of Japan show similar isotopic characteristics to basalts from the Mariana arc, supporting the idea that the <span class="hlt">Yamato</span> Basin Ridge is a spreading center causing separation of the northeast Japan Arc from Eurasia. ?? 1991.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19980004741','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980004741"><span id="translatedtitle">Workshop on Parent-Body and Nebular Modification of Chondritic Materials</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zolensky, M. E. (Editor); Krot, A. N. (Editor); Scott, E. R. D. (Editor)</p> <p>1997-01-01</p> <p>Topics considered include: thermal Metamorphosed Antarctic CM and CI Carbonaceous Chondrites in Japanese Collections, and Transformation Processes of Phyllosilicates; use of Oxygen Isotopes to Constrain the Nebular and Asteroidal Modification of Chondritic Materials; effect of Revised Nebular Water Distribution on Enstatite Chondrite Formation; interstellar Hydroxyls in Meteoritic Chondrules: Implications for the Origin of Water in the Inner Solar System; theoretical Models and Experimental Studies of Gas-Grain Chemistry in the Solar Nebula; chemical Alteration of Chondrules on Parent Bodies; thermal Quenching of Silicate Grains in Protostellar Sources; an Experimental Study of Magnetite Formation in the Solar Nebula; the Kaidun Meteorite: Evidence for Pre- and Postaccretionary Aqueous Alteration; a Transmission Electron Microscope Study of the Matrix Mineralogy of the Leoville CV3 (Reduced-Group) Carbonaceous Chondrite: Nebular and Parent-Body Features; rubidium-Strontium Isotopic Systematic of Chondrules from the Antarctic CV Chondrites <span class="hlt">Yamato</span> 86751 and <span class="hlt">Yamato</span> 86009: Additional Evidence for Late Parent-Body Modification; oxygen-Fugacity Indicators in Carbonaceous Chondrites: Parent-Body Alteration or High-Temperature Nebular Oxidation; thermodynamic Modeling of Aqueous Alteration in CV Chondrites; asteroidal Modification of C and O Chondrites: Myths and Models; oxygen Fugacity in the Solar Nebular; and the History of Metal and Sulfides in Chondrites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005GeoRL..3220202T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005GeoRL..3220202T"><span id="translatedtitle">Ion microprobe U-Pb dating of phosphates in lunar basaltic breccia, Elephant Moraine 87521</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Terada, Kentaro; Saiki, Tomoyo; Oka, Yoshimi; Hayasaka, Yasutaka; Sano, Yuji</p> <p>2005-10-01</p> <p>We report ion microprobe U-Pb dating of phosphates in lunar meteorite ``Elephant Moraine 87521 (EET87521),'' which is a fragmental breccia consisting of Very-Low Ti (VLT) basaltic clasts and a small component of highland-derived materials. The observed Pb-Pb age of phosphates in EET87521 is 3503 +/- 140 Ma, which is distinct from the results from previous chronological studies on VLT mare basalt of 3.2-3.3 Ga for LUNA-24. This suggests that the VLT basalt volcanism appears to have been prolonged on the Moon. Moreover, the age is apparently different from those of other VLT meteorites (3.8 Ga for QUE94281 and 4.0 & 4.4 Ga for <span class="hlt">Yamato</span>793274), which are proposed to have been launched by a single impact event based on the similarity of launching ages, mineralogical and geochemical signatures. This evidence questions the validities of bulk age analyses for the <span class="hlt">Yamato</span> & QUE meteorites in the literature and/or the hypothesis of a single-crater origin.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1992AIPC..256..583K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1992AIPC..256..583K"><span id="translatedtitle">Gold seal and Kyushu dynasty: Unsolved mysteries of ancient Japan</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kamimura, Masayasu</p> <p>1992-05-01</p> <p>A central dogma of the Japanese history is that, throughout the history, there was absolutely no other dynasty or kingdom than the dynasty of the Imperial House of Japan (<span class="hlt">Yamato</span> dynasty) which continues to exist since some 1500˜2000 years ago. Although much inconsistency has been noted between this dogma and accumulated records of Chinese historical documents on ancient Japan, almost all the Japanese historians have not taken such inconsistency seriously and even attributed it to mistakes or confusion of the Chinese historians who wrote the documents. But, one historian, Takehiko Furuta, who fully believes in the Chinese records, analyzed them recently in a very logical and even scientific manner and reached a surprising conclusion that there was a dynasty in northern Kyushu (Kyushu dynasty) and it was always this dynasty that appeared in the Chinese old records until 648 A.D., whereas the <span class="hlt">Yamato</span> dynasty which started as a branch of the Kyushu dynasty finally overcame the Kyushu dynasty around 700 A.D. This new theory seems to be supported by many archaeological discoveries in and around the Fukuoka area, one of the most notable examples of which is the Gold Seal that appears in the Symposium poster. These remind us of the famous story that Heinrich Scliemann who believed in Homer's The Iliad as real finally succeeded in excavating the ruins of Troy.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110007913','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110007913"><span id="translatedtitle">Comparisons of Mineralogy Between Cumulate Eucrites and Lunar Meteorites Possibly from the Farside Anorsothitic Crust</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Takeda, H.; Yamaguchi, A.; Hiroi, T.; Nyquist, L. E.; Shih, C.-Y.; Ohtake, M.; Karouji, Y.; Kobayashi, S.</p> <p>2011-01-01</p> <p>Anorthosites composed of nearly pure anorthite (PAN) at many locations in the farside highlands have been observed by the Kaguya multiband imager and spectral profiler [1]. Mineralogical studies of lunar meteorites of the Dhofar 489 group [2,3] and <span class="hlt">Yamato</span> (Y-) 86032 [4], all possibly from the farside highlands, showed some aspects of the farside crust. Nyquist et al. [5] performed Sm-Nd and Ar-Ar studies of pristine ferroan anorthosites (FANs) of the returned Apollo samples and of Dhofar 908 and 489, and discussed implications for lunar crustal history. Nyquist et al. [6] reported initial results of a combined mineralogical/chronological study of the <span class="hlt">Yamato</span> (Y-) 980318 cumulate eucrite with a conventional Sm-Nd age of 4567 24 Ma and suggested that all eucrites, including cumulate eucrites, crystallized from parental magmas within a short interval following differentiation of their parent body, and most eucrites participated in an event or events in the time interval 4400- 4560 Ma in which many isotopic systems were partially reset. During the foregoing studies, we recognized that variations in mineralogy and chronology of lunar anorthosites are more complex than those of the crustal materials of the HED parent body. In this study, we compared the mineralogies and reflectance spectra of the cumulate eucrites, Y-980433 and 980318, to those of the Dhofar 307 lunar meteorite of the Dhofar 489 group [2]. Here we consider information from these samples to gain a better understanding of the feldspathic farside highlands and the Vesta-like body.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20030111517&hterms=mantle&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dmantle','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20030111517&hterms=mantle&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dmantle"><span id="translatedtitle">Oxygen Fugacity of the Martian Mantle From Pyroxene/Melt Partitioning of REE</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Musselwhite, D. S.; Jones, J. H.</p> <p>2003-01-01</p> <p>This study is part of an ongoing effort to calibrate the pyroxene/melt REE oxybarometer for conditions relevant to the martian meteorites. Redox variations have been reported among the <span class="hlt">shergottites</span>. Wadhwa used the Eu and Gd augite/melt partitioning experiments of McKay, designed for the LEW86010 angrite, to infer a range of fo2 for the <span class="hlt">shergottites</span>. Others inferred fo2 using equilibria between Fe-Ti oxides. There is fairly good agreement between the Fe-Ti oxide determinations and the estimates from Eu anomalies in terms of which meteorites are more or less oxidized. The Eu anomaly technique and the Fe-Ti oxide technique both essentially show the same trend, with Shergotty and Zagami being the most oxidized and QUE94201 and DaG 476 being the most reduced. Thus, the variation in fo2 appears to be both real and substantive. However, although the redox trends indicated by the two techniques are similar, there is as much as two log unit offset between the results of three researchers. One explanation for this offset is that the Eu calibration used for the <span class="hlt">shergottites</span> was actually designed for the LEW86010 angrite, a silica-undersaturated basalt whose pyroxene (diopside) compositions are rather extreme. To correct this, experiments have been conducted on the redox relationship of Eu partitioning relative to Sm and Gd for pyroxene/melt compositions more relevant to Martian meteorites. We report here preliminary results for experiments on pigeonite/melt partitioning as a function of fO2.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016M%26PS..tmp..309M&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016M%26PS..tmp..309M&link_type=ABSTRACT"><span id="translatedtitle">Heterogeneous distribution of H2O in the Martian interior: Implications for the abundance of H2O in depleted and enriched mantle sources</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>McCubbin, Francis M.; Boyce, Jeremy W.; Srinivasan, Poorna; Santos, Alison R.; Elardo, Stephen M.; Filiberto, Justin; Steele, Andrew; Shearer, Charles K.</p> <p>2016-04-01</p> <p>We conducted a petrologic study of apatite within 12 Martian meteorites, including 11 <span class="hlt">shergottites</span> and one basaltic regolith breccia. These data were combined with previously published data to gain a better understanding of the abundance and distribution of volatiles in the Martian interior. Apatites in individual Martian meteorites span a wide range of compositions, indicating they did not form by equilibrium crystallization. In fact, the intrasample variation in apatite is best described by either fractional crystallization or crustal contamination with a Cl-rich crustal component. We determined that most Martian meteorites investigated here have been affected by crustal contamination and hence cannot be used to estimate volatile abundances of the Martian mantle. Using the subset of samples that did not exhibit crustal contamination, we determined that the enriched <span class="hlt">shergottite</span> source has 36-73 ppm H2O and the depleted source has 14-23 ppm H2O. This result is consistent with other observed geochemical differences between enriched and depleted <span class="hlt">shergottites</span> and supports the idea that there are at least two geochemically distinct reservoirs in the Martian mantle. We also estimated the H2O, Cl, and F content of the Martian crust using known crust-mantle distributions for incompatible lithophile elements. We determined that the bulk Martian crust has ~1410 ppm H2O, 450 ppm Cl, and 106 ppm F, and Cl and H2O are preferentially distributed toward the Martian surface. The estimate of crustal H2O results in a global equivalent surface layer (GEL) of ~229 m, which can account for at least some of the surface features on Mars attributed to flowing water and may be sufficient to support the past presence of a shallow sea on Mars' surface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19940007579&hterms=gases+combustion&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dgases%2Bcombustion','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19940007579&hterms=gases+combustion&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dgases%2Bcombustion"><span id="translatedtitle">Nitrogen and noble gases in a glass sample from LEW88516</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Becker, R. H.; Pepin, R. O.</p> <p>1993-01-01</p> <p>The Antarctic meteorite LEW88516 has been classified as a member of the SNC group of meteorites, specifically a <span class="hlt">shergottite</span>. It is reported to be remarkably similar in mineralogy, petrogenesis and chemistry to the previously known ALH77005 <span class="hlt">shergottite</span>, with both being compositionally distinct from other <span class="hlt">shergottites</span>. LEW88516 shows pervasive shock features and has been found to contain glass veins attributable to a shock origin. In an effort to determine whether the glass in LEW88516 contains any of the isotopically-heavy trapped nitrogen component observed in EETA 79001 glass, as well as the related high-Ar-40/Ar-36 and high-Xe-129/Xe-132 components, we undertook an analysis of an 11.9 mg glass sample (LEW88516,4) provided to us by H. Y. McSween, Jr. as part of a consortium study of this meteorite. Nitrogen and noble gases were extracted from LEW88516,4 in a series of combustion steps at increasing temperatures followed by a final pyrolysis. Initial steps at 550 C were intended to remove any surface-sited nitrogen-containing contaminants, while the 700 C step was expected to show the onset of release of a trapped argon component, based on our previous data for EETA 79001. It was hoped that the bulk of any trapped gas release would be concentrated in one of two steps at 1100 C and approximately 1400 C, maximizing our analytical sensitivity. Results of the analysis are shown. Except for He and Ne, data obtained for the 550 C steps will be omitted from further consideration on the assumption that they represent terrestrial contamination.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003EAEJA....11377M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003EAEJA....11377M"><span id="translatedtitle">Experimental melting of arc crustal pyroxenites and the origin of ultracalcic ne-normative melts in arc settings</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Médard, E.; Schiano, P.; Schmidt, M. W.</p> <p>2003-04-01</p> <p>Primitive ultracalcic melts have been documented at mid-ocean-ridges, back-arc basins, oceanic islands and volcanic arcs. Ultracalcic nepheline-normative melts in island arcs occurs both as glass inclusions and lavas (Schiano et al., G3, 2000). The high CaO contents (up to 18 wt%), low SiO_2 contents (down to 43 wt%) and high CaO/Al_2O_3 ratios (up to 1.2) of these melts cannot be simply explained by <span class="hlt">lherzolite</span> melting under anhydrous or hydrous conditions. <span class="hlt">Lherzolite</span> melting involving CO_2-rich fluids produces high-CaO/Al_2O_3 liquids, however, low amounts of CO_2 (500 ppm, Sisson and Bronto, Nature, 1998) have been mesured in arc-related ultracalcic glass inclusions. Ne-normative ultracalcic melts could be generated by melting of carbonate-bearing <span class="hlt">lherzolites</span> or by <span class="hlt">lherzolite</span> melting in the garnet stability field (as suggested for nephelinites and melilitites). However, the ultracalcic ne-normative melts observed in arcs do not bear the caracteristic trace-element signatures of these processes. Is it possible to generate ultracalcic ne-normative liquids without CO_2? In order to add new constraints on this problem, multiple saturation experiments and direct melting experiments were performed on ne-normative compositions. Model ultracalcic melts are in equilibrium with olivine and clinopyroxene at crustal pressures (0.2 -- 0.7 GPa) and temperatures near 1250^oC. These results suggest that in arc settings, such melts can be derived at crustal levels from partial melting of ol-cpx rich rocks. Therefore, melting experiments were conducted on amphibole-bearing cpx-ol compositions at 0.50--1.0 GPa. Partial melts are ultracalcic above 1220--1250^oC, and in equilibrium with ol and cpx. Compared to <span class="hlt">lherzolite</span> melting, cpx is more Ca-rich and a residual phase to higher melt fractions, so the maximum CaO content, reached at the cpx out, is higher. Mg# of melts increase with melt fraction, as do equilibrium Mg# of residual olivine (Fo82 to Fo89 at very high melt fraction</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013E%26PSL.362...66M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013E%26PSL.362...66M"><span id="translatedtitle">Mantle refertilization by melts of crustal-derived garnet pyroxenite: Evidence from the Ronda peridotite massif, southern Spain</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Marchesi, Claudio; Garrido, Carlos J.; Bosch, Delphine; Bodinier, Jean-Louis; Gervilla, Fernando; Hidas, Károly</p> <p>2013-01-01</p> <p>Geochemical studies of primitive basalts have documented the presence of crustal-derived garnet pyroxenite in their mantle sources. The processes whereby melts with the signature of garnet pyroxenite are produced in the mantle are, however, poorly understood and somewhat controversial. Here we investigate a natural example of the interaction between melts of garnet pyroxenite derived from recycled plagioclase-rich crust and surrounding mantle in the Ronda peridotite massif. Melting of garnet pyroxenite at ˜1.5 GPa generated spinel websterite residues with MREE/HREE fractionation and preserved the positive Eu anomaly of their garnet pyroxenite precursor in whole-rock and clinopyroxene. Reaction of melts from garnet pyroxenite with depleted surrounding peridotite generated secondary fertile spinel <span class="hlt">lherzolite</span>. These secondary <span class="hlt">lherzolites</span> differ from common spinel <span class="hlt">lherzolite</span> from Ronda and elsewhere by their lower-Mg# in clinopyroxene, orthopyroxene and olivine, lower-Cr# in spinel and higher whole-rock Al2O3, CaO, Sm/Yb and FeO* at a given SiO2. Remarkably, secondary spinel <span class="hlt">lherzolite</span> shows the geochemical signature of ghost plagioclase in the form of positive Eu and Sr anomalies in whole-rock and clinopyroxene, reflecting the transfer of a low-pressure crustal imprint from recycled pyroxenite to hybridized peridotite. Garnet pyroxenite melting and melt-peridotite interaction, as shown in the Ronda massif, may explain how the signature of subducted or delaminated crust is transferred to the mantle and how a garnet pyroxenite component is introduced into the source region of basalts. The efficiency of these processes in conveying the geochemical imprint of crustal-derived garnet pyroxenite to extruded lavas depends on the reactivity of pyroxenite melt with peridotite and the mantle permeability, which may be controlled by prior refertilization reactions similar to those documented in the Ronda massif. Highly fertile heterogeneities produced by pyroxenite</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010Litho.119..485M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010Litho.119..485M"><span id="translatedtitle">Age and geochemistry of mantle peridotites and diorite dykes from the Baldissero body: Insights into the Paleozoic-Mesozoic evolution of the Southern Alps</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mazzucchelli, Maurizio; Zanetti, Alberto; Rivalenti, Giorgio; Vannucci, Riccardo; Correia, Ciro Teixeira; Tassinari, Colombo Celso Gaeta</p> <p>2010-10-01</p> <p>Trace element and isotopic data obtained for mantle spinel <span class="hlt">lherzolites</span> and diorite dykes from the Baldissero massif (Ivrea-Verbano Zone, Western Italy) provide new, valuable constraints on the petrologic and geodynamic evolution of the Southern Alps in Paleozoic to Mesozoic times. Whole rock and mineral chemistry indicates that Baldissero <span class="hlt">lherzolites</span> can be regarded as refractory mantle residues following limited melt extraction. In particular, the Light Rare Earth Elements (LREE)-depleted and fractionated compositions of whole rock and clinopyroxene closely match modelling results for refractory residues after low degrees (~ 4-5%) of near-fractional melting of depleted mantle, possibly under garnet-facies conditions. Following this, the peridotite sequence experienced subsolidus re-equilibration at lithospheric spinel-facies conditions and intrusion of several generations of dykes. However, <span class="hlt">lherzolites</span> far from dykes show very modest metasomatic changes, as evidenced by the crystallisation of accessory titanian pargasite and the occurrence of very slight enrichments in highly incompatible trace elements (e.g. Nb). The Re-Os data for <span class="hlt">lherzolites</span> far from the dykes yield a 376 Ma (Upper Devonian) model age that is considered to record a partial melting event related to the Variscan orogenic cycle s.l. Dioritic dykes cutting the mantle sequence have whole rock, clinopyroxene and plagioclase characterised by high radiogenic Nd and low radiogenic Sr, which point to a depleted to slightly enriched mantle source. Whole rock and mafic phases of diorites have high Mg# values that positively correlate with the incompatible trace element concentrations. The peridotite at the dyke contact is enriched in orthopyroxene, iron and incompatible trace elements with respect to the <span class="hlt">lherzolites</span> far from dykes. Numerical simulations indicate that the geochemical characteristics of the diorites can be explained by flow of a hydrous, silica-saturated melt accompanied by reaction with the</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013Litho.170...90V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013Litho.170...90V"><span id="translatedtitle">The provenance of sub-cratonic mantle beneath the Limpopo Mobile Belt (South Africa)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>van der Meer, Quinten H. A.; Klaver, Martijn; Waight, Tod E.; Davies, Gareth R.</p> <p>2013-06-01</p> <p>Petrological, whole rock major element and mineral chemical analysis of mantle xenoliths from the Venetia kimberlite pipes (533 Ma) in South Africa reveals an apparently stratified cratonic mantle beneath the Central Zone of the Limpopo Mobile Belt (LMB) that separates the Kaapvaal and Zimbabwe Cratons. Combined pressure-temperature (P-T) data and petrographic observations indicate that the mantle consists of an upper layer of Low-T coarse-equant garnet + spinel <span class="hlt">lherzolite</span> (~ 50 to ~ 130 km depth). This layer is underlain by a region of mixed garnet harzburgites and garnet <span class="hlt">lherzolites</span> that are variably deformed (~ 130 to ~ 235 km depth). An equilibrated geotherm did not exist at the time of kimberlite eruption (533 Ma) and a localised heating event involving the introduction of asthenospheric material to the High-T lithosphere below 130 km is inferred. Low-T garnet-spinel <span class="hlt">lherzolites</span> are highly melt depleted (40% on average). In contrast, the High-T lithosphere (mostly at diamond stable conditions) consists of a mixed zone of variably sheared and melt depleted (30% on average) garnet harzburgite and mildly melt depleted (20% on average) garnet <span class="hlt">lherzolite</span>. The chemistry of the High-T xenoliths contrasts with that of minerals included in diamond originating from the same depth. Inclusions suggest diamond crystallisation in a more melt depleted lithosphere than represented by either Low- or High-T xenoliths. High-T xenoliths are proposed to represent formerly melt depleted lithosphere, refertilised by asthenosphere-derived melts during the diapiric rise of a proto-kimberlitic melt pocket. This process is coupled to the positive temperature perturbation observed in the High-T xenoliths and may represent a common process in the lower lithosphere related to localised but intense tectono-magmatic events immediately preceding kimberlite eruption. The presence of clinopyroxene, garnet and abundant orthopyroxene in the Low-T <span class="hlt">lherzolite</span> implies a history of melt depletion</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016Litho.248..339K&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016Litho.248..339K&link_type=ABSTRACT"><span id="translatedtitle">Asthenosphere-lithosphere interactions in Western Saudi Arabia: Inferences from 3He/4He in xenoliths and lava flows from Harrat Hutaymah</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Konrad, Kevin; Graham, David W.; Thornber, Carl R.; Duncan, Robert A.; Kent, Adam J. R.; Al-Amri, Abdullah M.</p> <p>2016-04-01</p> <p>Extensive volcanic fields on the western Arabian Plate have erupted intermittently over the last 30 Ma following emplacement of the Afar flood basalts in Ethiopia. In an effort to better understand the origin of this volcanism in western Saudi Arabia, we analyzed 3He/4He, and He, CO2 and trace element concentrations in minerals separated from xenoliths and lava flows from Harrat Hutaymah, supplemented with reconnaissance He isotope data from several other volcanic fields (Harrat Al Birk, Harrat Al Kishb and Harrat Ithnayn). Harrat Hutaymah is young (< 850 ka) and the northeasternmost of the volcanic fields. There is a remarkable homogeneity of 3He/4He trapped within most xenoliths, with a weighted mean of 7.54 ± 0.03 RA (2σ, n = 20). This homogeneity occurs over at least eight different xenolith types (including spinel <span class="hlt">lherzolite</span>, amphibole clinopyroxenite, olivine websterite, clinopyroxenite and garnet websterite), and encompasses ten different volcanic centers within an area of ~ 2500 km2. The homogeneity is caused by volatile equilibration between the xenoliths and fluids derived from their host magma, as fluid inclusions are annealed during the infiltration of vapor-saturated magmas along crystalline grain boundaries. The notable exceptions are the anhydrous spinel <span class="hlt">lherzolites</span>, which have a lower weighted mean 3He/4He of 6.8 ± 0.3 RA (2σ, n = 2), contain lower concentrations of trapped He, and have a distinctly depleted light rare earth element signature. 3He/4He values of ~ 6.8 RA are also commonly found in spinel <span class="hlt">lherzolites</span> from harrats Ithnayn, Al Birk, and from Zabargad Island in the Red Sea. Olivine from non-xenolith-bearing lava flows at Hutaymah spans the He isotope range of the xenoliths. The lower 3He/4He in the anhydrous spinel <span class="hlt">lherzolites</span> appears to be tied to remnant Proterozoic lithosphere prior to metasomatic fluid overprinting. Elevated 3He/4He in the western harrats has been observed only at Rahat (up to 11.8 RA; Murcia et al., 2013), a</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2007Litho..99..136K&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2007Litho..99..136K&link_type=ABSTRACT"><span id="translatedtitle">Petrogenetic significance of spinel-group minerals from the ultramafic rocks of the Iti and Kallidromon ophiolites (Central Greece)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Karipi, Sofia; Tsikouras, Basilios; Hatzipanagiotou, Konstantin; Grammatikopoulos, Tassos A.</p> <p>2007-11-01</p> <p>The peridotites occurring at Iti and Kallidromon ophiolites comprise <span class="hlt">lherzolite</span> with lensoid dunitic bodies (only at Kallidromon) and harzburgite. The <span class="hlt">lherzolite</span> contains spinel of aluminous composition forming subhedral to anhedral grains with lobate boundaries. The dunite and harzburgite contain chromite and magnesiochromite, respectively, forming subhedral to euhedral grains. The dunitic chromite displays commonly richer-in-Cr core compositions rimmed by poorer-in-Cr ones. Infrequently, the magnesiochromitic rims show irregular distribution of small areas of poorer-in-Cr composition. On the basis of their Cr#, the <span class="hlt">lherzolitic</span> spinels and the harburgitic magnesiochromites are analogous to those from abyssal peridotites and oceanic (including back-arc basins) ophiolites, whereas the chromites in the dunite resemble those from arc-related ophiolitic sequences. The <span class="hlt">lherzolitic</span> spinels show a linear covariation of Cr# with Mg#, compatibly with their being products of restricted partial melting. The richer-in-Cr chromites cluster at high Cr#, as a result of their crystallization from a boninitic melt while the poorer-in-Cr chromites and the magnesiochromites show a linear covariation, with the latter being the Cr-poor end-member of that trend, suggesting crystallization during the evolution of the boninitic melt that interacted with the mantle peridotites. The dunite formation is assigned to the interaction of that melt with the <span class="hlt">lherzolite</span> after consuming pyroxenes and crystallizing olivine and chromite. This melt subsequently migrated upwards in the harzburgite and evolved, thus magnesiochromite, lower in Cr#, was crystallized. Textural evidence and mineral chemistry data from the harzburgitic magnesiochromite are in agreement with a melt-peridotite interaction after a partial melting event. Later hydrothermal alteration imprinted in the samples by forming ferrian chromite and magnetite at the expense of the spinel-group minerals and developing the silicate</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20100010148','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20100010148"><span id="translatedtitle">Sm-Nd Isotopic Studies of Two Nakhlites, NWA 5790 and Nakhla</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>C.-Y. Shih; Nyquist, L. E.; Reese, Y.; Jambon, A.</p> <p>2010-01-01</p> <p>NWA 5790 is a Martian meteorite recently found in the Mauritania part of the Saharan desert and is classified as a nakhlite, containing a small amount of interstitial plagioclase. Unlike other Martian meteorites ( e.g., <span class="hlt">shergottites</span>), nakhlites have been only moderately shocked and their original igneous textures are still well-preserved. In this report, we present Sm-Nd isotopic data for NWA 5790 and Nakhla, a rare "fall" nakhlite, correlate their ages with those of other nakhlites and discuss their petrogenesis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19860029054&hterms=PRIMUS&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DPRIMUS','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19860029054&hterms=PRIMUS&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DPRIMUS"><span id="translatedtitle">Sulfur in achondritic meteorites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gibson, E. K.; Moore, C. B.; Primus, T. M.; Lewis, C. F.</p> <p>1985-01-01</p> <p>The sulfur abundances of samples of nearly 50 achondrites were examined to enlarge the database on the sulfur contents of various categories of achondrites. The study covered eucrites, howardites, diogenites, <span class="hlt">shergottites</span>, chassignites, nakhilites, aubrites and three unique specimens. The study was spurred by the possibility that the S abundances could help identify the meteorites as originating on Mars or Venus. The S abundances and distributions varied widely, but confirmed that the data were valid indicators of the brecciation and thermal metamorphic history of each meteorite.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.P51E3986O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.P51E3986O"><span id="translatedtitle">What Can Spectral Properties of Martian Surface and Snc Can Tell Us about the Martian Crust Composition and Evolution</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ody, A.; Poulet, F.; Baratoux, D.; Quantin, C.; Bibring, J. P.</p> <p>2014-12-01</p> <p>While the study of Martian meteorites can provide detailed information about the crust and mantle composition and evolution, remote-sensing observations, through the merging of compositional and geological data, allow highlighting planetary-scale trends of the Martian crustal evolution [1,2]. Recently, the analysis of the global distribution of mafic minerals [3] has put new constraints on the Martian crust formation and evolution. One of the major results is a past global event of olivine-bearing fissural volcanism that has filled craters and low depressions in the southern highlands and a large part of the Northern plains during the late Noachian/early Hesperian. Petrologic models show that this sudden increase of the olivine content at the Noachian-Hesperian boundary could be the result of a rapid thickening of the lithosphere at the end of the Noachian era [4]. A recent study based on the OMEGA/MEx data has shown that the spectral properties of the <span class="hlt">shergottites</span> are similar to those of some Noachian and Hesperian terrains [5]. To contrary, the Nakhla spectral properties are very different from those of the observable surface and could be representative of Amazonian terrains buried under dust. These results are best explained with an old age of the <span class="hlt">shergottites</span> [6] and with the present understanding of the evolution of magma composition at a planetary scale [7]. On the other hand, if <span class="hlt">shergottites</span> are young [8], the similarities between the <span class="hlt">shergottites</span> and ancient terrains implies that exceptional conditions of melting with respect to the ambient mantle (e.g., hot spots or water-rich mantle source) were responsible for the formation of these samples [9]. References: [1] McSween et al., 2009, Science, 324. [2] Ehlmann & Edwards 2014, AREPS, vol. 42. [3] Ody et al., 2013, JGR,117,E00J14. [4] Ody et al., 2014, 8th Inter. Conf. on Mars,#1190. [5] Ody et al., 2013, 44th LPSC, #1719. [6] Bouvier et al., 2009, EPSL, 280. [7] Baratoux et al., 2013, JGR, 118. [8] Nyquist</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1991SSRv...56...23O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1991SSRv...56...23O"><span id="translatedtitle">Composition of the Martian atmosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ott, U.</p> <p>1991-04-01</p> <p>Data on the composition of the Martian atmosphere obtained by instruments aboard the Viking spacecraft are not of sufficient accuracy to address important questions regarding the compsition and history of Mars. Laboratory analyses of gases trapped in glassy phases of <span class="hlt">shergottite</span> meteorite EETA 79001 yield precise data, but it remains to be ascertained that these gases constitute unfractionated Martian atmosphere. Return from Mars of a gas sample for laboratory analysis appears preferable to another in situ measurement, especially if rocks of documented origin will become available for gas analysis as well.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1986GeCoA..50..955C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1986GeCoA..50..955C"><span id="translatedtitle">Formation ages and evolution of Shergotty and its parent planet from U-Th-Pb systematics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, J. H.; Wasserburg, G. J.</p> <p>1986-06-01</p> <p>The isotopic composition of Pb from Shergotty, Zagami, and EETA 79001 meteorites was determined for different phases. Using phases with low U-238/Pb-204 ratio, the initial leads of these meteorites were defined. Samples from all three meteorites were shown to have distinct initial leads, and, thus to have evolved from different reservoirs over most of solar system history in a low U-238/Pb-204 environment. It follows that the parent planet of the <span class="hlt">shergottites</span> has a high Pb-204 concentration relative to U and must also be high in other volatiles. The possibility of the Martian origin of the SNC-type meteorites is discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/17737107','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/17737107"><span id="translatedtitle">Maskelynite: Formation by Explosive Shock.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Milton, D J; de Carli, P S</p> <p>1963-05-10</p> <p>When high pressure (250 to 300 kilobars) was applied suddenly (shock-loading) to gabbro, the plagioclase was transformed to a noncrystalline phase (maskelynite) by a solid-state reaction at a low temperature, while the proxene remained crystalline. The shock-loaded gabbro resembles meteorites of the <span class="hlt">shergottite</span> class; this suggests that the latter formed as a result of shock. The shock-loading of gabbro at 600 to 800 kilobars raised the temperature above the melting range of the plagioclase. PMID:17737107</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19930030880&hterms=water+chemistry&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26Nf%3DPublication-Date%257CLT%2B20121231%26N%3D0%26No%3D90%26Ntt%3Dwater%2Bchemistry','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19930030880&hterms=water+chemistry&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26Nf%3DPublication-Date%257CLT%2B20121231%26N%3D0%26No%3D90%26Ntt%3Dwater%2Bchemistry"><span id="translatedtitle">Soil mineralogy and chemistry on Mars - Possible clues from salts and clays in SNC meteorites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gooding, James L.</p> <p>1992-01-01</p> <p>If the <span class="hlt">shergottite</span>, nakhlite, and chassignite (SNC) meteorites' parent planet is Mars, then the aqueous precipitates found in them imply that oxidizing, water-based solutions may have been chemically active on that planet over the past 200-1300 million yrs. It is suggested that the mixture of aqueous precipitates found in the SNCs furnish a self-consistent model for the bulk elemental composition of surface sediments at the Viking Lander sites. Further mineralogical and stable-isotope studies of the secondary minerals may establish the limits for biological activity over the last 1300 million years of Mars' water-based chemistry.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930014003','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930014003"><span id="translatedtitle">Workshop on chemical weathering on Mars, part 2</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Burns, Roger (Editor); Banin, Amos (Editor)</p> <p>1992-01-01</p> <p>The third Mars Surface and Atmosphere Through Time (MSATT) Workshop, which was held 10-12 Sep. 1992, at Cocoa Beach/Cape Kennedy, focused on chemical weathering of the surface of Mars. The 30 papers presented at the workshop described studies of Martian weathering processes based on results from the Viking mission experiments, remote sensing spectroscopic measurements, studies of the <span class="hlt">shergottite</span>, nakhlite, and chassignite (SNC) meteorites, laboratory measurements of surface analog materials, and modeling of reaction pathways. A summary of the technical sessions is presented and a list of workshop participants is included.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20070003720','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20070003720"><span id="translatedtitle">Ar-39-Ar-40 Ages of Two Nakhlites, MIL03346 and Y000593: A Detailed Analysis</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Park, Jisun; Garrison, Daniel; Bogard, Donald</p> <p>2007-01-01</p> <p>Radiometric dating of martian nakhlites by several techniques have given similar ages of approx.1.2-1.4 Ga [e.g. 1, 2]. Unlike the case with <span class="hlt">shergottites</span>, where the presence of martian atmosphere and inherited radiogenic Ar-40 produce apparent Ar-39-Ar-40 ages older than other radiometric ages, Ar-Ar ages of nakhlites are similar to ages derived by other techniques. However, even in some nakhlites the presence of trapped martian Ar produces some uncertainty in the Ar-Ar age. We present here an analysis of such Ar-Ar ages from the MIL03346 and Y000593 nakhlites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19940007544&hterms=Bohr+Niels&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3D%2528Bohr%2BNiels%2529','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19940007544&hterms=Bohr+Niels&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3D%2528Bohr%2BNiels%2529"><span id="translatedtitle">Moessbauer spectroscopy of the SNC meteorite Zagami</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Agerkvist, D. P.; Vistisen, L.</p> <p>1993-01-01</p> <p>We have performed Mossbauer spectroscopy on two different pieces of the meteorite Zagami belonging to the group of SNC meteorites. In one of the samples we found a substantial amount of olivine inter grown with one kind of pyroxene, and also another kind of pyroxene very similar to the pyroxene in the other sample we examined. Both samples showed less than 1 percent of Fe(3+) in the silicate phase. The group of SNC meteorites called <span class="hlt">shergottites</span>, to which Zagami belongs, are achondrites whose texture, mineralogy and composition resembles those of terrestrial diabases. The results from the investigation are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080026344','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080026344"><span id="translatedtitle">Ar-Ar Dating of Martian Chassignites, NWA2737 and Chassigny, and Nakhlite MIL03346</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bogard, D. D.; Garrison, D. H.</p> <p>2006-01-01</p> <p>Until recently only three nakhlites and one chassignite had been identified among martian meteorites. These four exhibit very similar radiometric ages and cosmic ray exposure (CRE) ages, indicating that they may have derived from a common location on Mars and were ejected into space by a single impact. This situation is quite different from that of martian <span class="hlt">shergottites</span>, which exhibit a range of radiometric ages and CRE ages (1). Recently, several new nakhlites and a new martian dunite (NWA2737) have been recognized. Here we report our results of Ar-39-Ar-40 dating for the MIL03346 nakhlite and the NWA2737 "chassignite", along with new results on Chassigny.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19920001032&hterms=Peridotite&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DPeridotite','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19920001032&hterms=Peridotite&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DPeridotite"><span id="translatedtitle">Clays on Mars: Review of chemical and mineralogical evidence</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Banin, Amos; Gooding, James L.</p> <p>1991-01-01</p> <p>Mafic igneous bedrock is inferred for Mars, based on spectrophotometric evidence for pyroxene (principally in optically dark areas of the globe) and the pyroxenite-peridotite petrology of <span class="hlt">shergottite</span> nakhlite chassignite (SNC) meteorites. Visible and infrared spectra of reddish-brown surface fines (which dominate Martian bright areas) indicate ferric iron and compare favorably (though not uniquely) with spectra of palagonitic soils. Laboratory studies of SNC's and Viking Lander results support a model for Martian soil based on chemical weathering of mafic rocks to produce layer structured silicates (clay minerals), salts, and iron oxides.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19980002913','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980002913"><span id="translatedtitle">Phase Equilibrium Investigations of Planetary Materials</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Grove, T. L.</p> <p>1997-01-01</p> <p>This grant provided funds to carry out experimental studies designed to illuminate the conditions of melting and chemical differentiation that has occurred in planetary interiors. Studies focused on the conditions of mare basalt generation in the moon's interior and on processes that led to core formation in the <span class="hlt">Shergottite</span> Parent Body (Mars). Studies also examined physical processes that could lead to the segregation of metal-rich sulfide melts in an olivine-rich solid matrix. The major results of each paper are discussed below and copies of the papers are attached as Appendix I.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..1412161M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..1412161M"><span id="translatedtitle">Mineral and whole rock compositions of peridotites from Loma Caribe (Dominican Republic): insights into the evolution of the oceanic mantle in the Caribbean region</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Marchesi, C.; Garrido, C. J.; Proenza, J. A.; Konc, Z.; Hidas, K.; Lewis, J.; Lidiak, E.</p> <p>2012-04-01</p> <p>Several mantle peridotite massifs crop out as isolated dismembered bodies in tectonic belts along the northern margin of the Caribbean plate, especially in Cuba, Guatemala, Jamaica, Hispaniola and Puerto Rico. Among these bodies, the Loma Caribe peridotite forms the core of the Median Belt in central Dominican Republic and is considered to have been emplaced in Aptian time as result of the collision between an oceanic plateau (the Duarte plateau terrane) and the primitive Caribbean island arc. This peridotite massif is mainly composed of clinopyroxene-rich harzburgite, harzburgite, <span class="hlt">lherzolite</span> and dunite which mainly have porphyroclastic texture with strongly deformed orthopyroxene porphyroclasts, as commonly observed in ophiolitic mantle tectonites. Mg# [100*Mg/(Mg+Fe2+)] of olivine increases from lower values in <span class="hlt">lherzolite</span> (89-90), to higher values in harzburgite (89-91) and dunite (91-92). Orthopyroxene in harzburgite has higher Mg# (91-92) and lower Al2O3 (0.89 to 1.12 wt.%) than in <span class="hlt">lherzolite</span> (Mg# = 89-91; Al2O3 = 2.4-3.5wt.%), similarly to clinopyroxene (Mg# = 94-95 and Al2O3 = 0.89-1.10 wt% in harzburgite, versus Mg# = 86-94 and Al2O3 = 2.3-4.0 wt% in <span class="hlt">lherzolite</span>). Cr# [Cr/(Cr+Al)] of spinel spans from 0.30 in <span class="hlt">lherzolite</span> to 0.88 in dunite. These variations in terms of Mg# in olivine and Cr# in spinel overlap the mineral compositions in both abyssal and supra-subduction zone peridotites. The sample/chondrite REE concentrations of peridotites are variable (0.002 < LREE chondrite-normalized < 0.11 and 0.002 < HREE chondrite-normalized < 1.02) and their HREE contents generally reflect the clinopyroxene proportions in the samples, i.e. harzburgite has lower HREE abundances than <span class="hlt">lherzolite</span>. These trace element abundances are transitional between those of highly depleted supra-subduction peridotites from ophiolites in eastern Cuba and those of fertile mantle rocks in ultramafic massifs from Puerto Rico. Chondrite-normalized patterns are U-shaped (i.e., relatively</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFM.V23D0651L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFM.V23D0651L"><span id="translatedtitle">Kinetics of Peridotite and Pyroxenite-derived Melts Interaction: Implications for the Style and Extent of Melt-rock Reaction in the Mantle</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lo Cascio, M.; Liang, Y.</p> <p>2006-12-01</p> <p>Distinct geochemical and petrologic features of ocean floor basalts and mantle peridotites suggest that the upper mantle is lithologically heterogeneous, consisting predominantly of peridotite and a small amount of eclogite [1]. An important issue of this marble cake mantle, is the nature of the peridotite and pyroxenite interface during mantle melting. It has been suggested that during mantle melting eclogite and peridotite develop a reactive boundary layer composed of a second generation eclogite and a layer of orthopyroxenite [2]. The existence of such a boundary layer has also been used to explain the observation that oceanic basalts are extracted with only limited interaction with the surrounding peridotite [3]. In spite of recent progresses, the kinetics of peridotite and pyroxenite-derived melts reaction is still not well understood. It is likely that there are two regimes of peridotite-pyroxenite melt interaction: a high T/low P regime where both the peridotite and pyroxenite are partially molten; and a low T/high P regime where only pyroxenite is partially molten. In this study we explored the kinetics of such interactions in both regimes by conducting <span class="hlt">lherzolite</span> dissolution experiments using a pyroxenite-derived melt at 1300°C and 1-2 GPa. Dissolution couples were formed by juxtaposing pre-synthesized rods of a basaltic andesite (54.6% SiO2, Mg# 0.42), whose composition is similar to pyroxenite derived liquid at 1300°C and 2 GPa [1,4], and a <span class="hlt">lherzolite</span> (ol+opx+cpx) in a Pt and graphite lined Mo capsule. The <span class="hlt">lherzolite</span> solidus is below 1300°C at 1 GPa [5], but above 1300°C at 2 GPa. <span class="hlt">Lherzolite</span> hardly dissolves (~35 μm in 6 hours) into the melt at 2 GPa and a thin opx layer (<10 μm thick) decorated with a few garnet crystals is observed at the <span class="hlt">lherzolite</span>-melt interface. From the concentration profiles of Al2O3 and MgO in the melt, we estimated the effective binary diffusion coefficient at 10^{-12}m2/s. Assuming an average mantle upwelling rate of ~50</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..1413129K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..1413129K"><span id="translatedtitle">Petrogenetic implications from ultramafic rocks and pyroxenites in ophiolitic occurrences of East Othris, Greece</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Koutsovitis, P.; Magganas, A.</p> <p>2012-04-01</p> <p>Ultramafic rocks and pyroxenites in east Othris are included within ophiolitic units near the villages of Vrinena, Karavomilos, Pelasgia, Eretria, Agios Georgios, Aerino and Velestino. The first five ophiolitic occurrences are estimated to have been emplaced between the Oxfordian and Tithonian-Berriasian[1,2,3], while the latter two have been emplaced during the Eocene[4]. Ultramafic rocks include variably serpentinized harzburgites and <span class="hlt">lherzolites</span>. Pyroxenites are usually found in the form of crosscutting veins within the harzburgites. Ultramafic rocks include depleted <span class="hlt">lherzolites</span>, with Al2O3 ranging from 1.12 to 1.80 wt% and Cr from 3250 to 3290 ppm, as well as moderate to highly depleted serpentinized harzburgites, with Al2O3 ranging from 0.69 to 1.98 wt% and Cr from 2663 to 5582 ppm. Pyroxenites have generally higher Al2O3 ranging from 1.91 to 3.08 wt% and variable Cr ranging from 1798 to 3611 ppm. <span class="hlt">Lherzolites</span> mostly include olivines (Fo=87.07-89.23) and clinopyroxenes (Mg#=85.71-90.12). Spinels from Eretria <span class="hlt">lherzolite</span> (TiO2=0.02-0.08 wt%, Al2O3=36.06-42.45 wt%, Cr#=31.67-36.33) are compositionally similar with those of MORB peridotites[5], while those from Vrinena <span class="hlt">lherzolite</span> (TiO2=0.16-0.43 wt%, Al2O3=6.90-22.12 wt%, Cr#=57.69-76.88) are similar to SSZ peridotites[5]. Serpentinized harzburgites include few olivines (Fo=90.51-91.15), enstatite porphyroclasts (Mg#=87.42-88.91), as well as fine grained enstatites of similar composition. Harzburgites from Pelasgia, Eretria and Agios Georgios include spinels (TiO2=0.03-0.08 wt%, Al2O3=23.21-31.58 wt%, Cr#=45.21-56.85) which do not clearly show if they are related with MORB or SSZ peridotites[5]. Spinels from Karavomilos harzburgite (TiO2=0.02-0.05 wt%, Al2O3=45.71-50.85 wt%, Cr#=16.84-22.32) are compositionally similar with MORB peridotites[5], whereas spinels from Vrinena harzburgite (TiO2=0.15-0.19 wt%, Al2O3=1.42-1.86 wt% Cr#=91.64-93.47) with SSZ peridotites[5]. Pyroxenites include clinopyroxenes (Mg#=84</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015EGUGA..1712007P&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015EGUGA..1712007P&link_type=ABSTRACT"><span id="translatedtitle">Petrological study of Greene Point mantle xenoliths, Northern Victoria Land, Antarctica.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pelorosso, Beatrice; Bonadiman, Costanza; Faccini, Barbara; Coltorti, Massimo; Ntaflos, Theodoros; Grégoire, Michel</p> <p>2015-04-01</p> <p>A petrological study of mantle, anhydrous spinel-bearing <span class="hlt">lherzolites</span> and harzburgites from Greene Point (GP) (Northern Victoria Land, NVL) have been carried out. Texturally they vary from protogranular to porphyroclastic with large orthopyroxene (opx) and olivine (ol) grains. Clinopyroxene (cpx) is smaller and often associated with vermicular and lobated spinel (sp). Several types of reaction textures occur with secondary phases represented by olivine (ol2), clinopyroxene (cpx2), cpx with spongy rim, and glass. Ol in <span class="hlt">lherzolites</span> presents lower forsteritic content (90.5-91.7) than in harzburgites (Fo: 91.6-92.3), but for three samples with an anomalously high Fo contents (92.3-92.7). Irrespective of lithology NiO contents are on the average ~0.38 wt%. Opx, equilibrated with ol1, has mg# (Mg/(Mg+Fe)*100mol) values ranging from 91.0 to 92.6 with the highest values found in harzburgites. As for Ol, however three <span class="hlt">lherzolitic</span> samples have mg# in opx overlapping the most residual harzburgites; Al2O3 varies from 2.33 to 4.92 wt% following a residual trend. Opx is characterized by fractionated REE-chondrite normalized patterns, depleted in light REE (LREE), with the most residual character in harzburgites. Cpx1 has mg# varying from 91.5 to 93.9, with cpx in harzburgites presenting the highest values. As for the other two phases, cpx in three <span class="hlt">lherzolites</span> presents mg# values comparable with those of harzburgites. Al2O3 contents is between 4.00 and 6.42 wt% in <span class="hlt">lherzolites</span> and from 2.32 to 4.37 wt% in harzburgites. TiO2 never exceeds 0.66 wt%. Cpx in <span class="hlt">lherzolites</span> are usually depleted in Th, U, Nb, and Ta with Ti, Zr and Hf negative anomalies. They present a REE patterns variable from slightly LREE-enriched (with La and Ce inflections) to LREE-depleted with a general convex-upward trend. This latter trend is related to mg# rich <span class="hlt">lherzolites</span>. In harzburgites cpx show the lowest HREE contents (YbN 1.00-2.94), with a strong positive fractionated L-MREE and flat HREE. Sp1 show a</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015EGUGA..1712342P&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015EGUGA..1712342P&link_type=ABSTRACT"><span id="translatedtitle">Petrological features of mantle xenoliths from Handler Ridge, Northern Victoria Land (NVL) , Antarctica</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pelorosso, Beatrice; Bonadiman, Costanza; Coltorti, Massimo; Giacomoni, Pier Paolo; Ntaflos, Theodoros; Grégoire, Michel</p> <p>2015-04-01</p> <p>A petrological study of ultramafic xenoliths from Handler Ridge has been carried out, in order to characterize the lithospheric mantle domain of the Western Antarctic Rift System, from Mt Melbourne (74°21'S 164°42'E) to Handler Ridge (72°31'167°18'E). Samples are mainly anhydrous spinel (sp)-bearing <span class="hlt">lherzolites</span>, but few wehrlites also occur. Two textures were recognized: i) medium to coarse grained and ii) fine grained types. Evidences of melt/rock interaction (secondary clinopyroxene cpx2, cpx spongy and cloudy rims, glassy patches) can be also observed. Olivine (ol) is forsteritic in composition with Fo varying from 87.5 to 91.0. Within <span class="hlt">lherzolites</span> a more fertile group can be recognized with Fo ranging between 87.5 and 88.6. In wehrlites ol varies from Fo 84.5 to 86.1. NiO ranges from 0. 28 to 0.44 wt% for <span class="hlt">lherzolites</span>, while it has a lower content for wehrlites (0.20-0.40 wt%) As for ol, orthopyroxene (opx) in the most fertile <span class="hlt">lherzolites</span> presents mg# from 88.1 to 88.3, while it varies from 88.3 to 91 in the residual <span class="hlt">lherzolitic</span> group. None differences in Al2O3 and TiO2 contents between the two groups were recognized. In chondrite-normalized incompatible element patterns opx is depleted in light REE (LREE), with remarkable Ti and Zr positive anomalies. In <span class="hlt">lherzolites</span> mg# of primary clinopyroxene (cpx1) varies between 87.6 and 92.1. As for ol and opx, two groups can be recognized, although some overlap exists for two samples. Al2O3 and TiO2 vary from 3.68-6.51 wt% and from 0.19 to 0.71 wt% respectively. Secondary cpx (cpx2) is generally richer in FeO, TiO2 and N2O with respect to cpx1. In wehrlites cpx is characterized by very low mg# (84.3-88.6) and higher TiO2 contents (0.69-1.39 wt%) than <span class="hlt">lherzolites</span>. Irrespective to the lithology, chondrite-normalized incompatible trace element cpx1 patterns are variable enriched in Th, U, Nb, and Ta with negative Sr, Zr and Hf anomalies. Two trends can be recognized. The first one with (La/Yb)N varying from 1.28 to 9</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013GeCoA.108...21W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013GeCoA.108...21W"><span id="translatedtitle">Partial re-equilibration of highly siderophile elements and the chalcogens in the mantle: A case study on the Baldissero and Balmuccia peridotite massifs (Ivrea Zone, Italian Alps)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Zaicong; Becker, Harry; Gawronski, Timo</p> <p>2013-05-01</p> <p>The conditions at which melt percolation and reactive infiltration of depleted mantle peridotites fractionate highly siderophile elements (HSE) and cause re-equilibration of 187Os/188Os in mantle rocks are still poorly constrained. In a comparative study of the Paleozoic Balmuccia (BM) and Baldissero (BD) peridotite tectonites (Ivrea-Verbano Zone, Northern Italy), the influence of partial melting and melt infiltration on abundances of HSE, chalcogens (S, Se and Te) and 187Os/188Os have been studied. At BM, Re depletion ages (TRD) of <span class="hlt">lherzolites</span> and replacive dunites display a uniform distribution with a maximum near 400-500 Ma. BD peridotites also display a Paleozoic distribution peak but a significant number of samples yielded Proterozoic TRD. The predominance of Paleozoic Re depletion ages in both bodies is consistent with Sm-Nd ages and the late Paleozoic magmatic and geodynamic evolution of the Ivrea-Verbano Zone. The different extents of preservation of ancient 187Os/188Os in BM and BD peridotites are interpreted to reflect different degrees of isotopic homogenization and chemical re-equilibration with incompatible element-depleted infiltrating melt during the Paleozoic. The differences between the two bodies are also reflected by differences in HSE and chalcogen abundances, with BD displaying large scatter among HSE patterns, slight re-enrichment of Re relative to Au, and linear trends of Pd, Se and Te with Al2O3. The differences in distributions of model ages and heterogeneity in HSE abundances support the view that the lithophile element, HSE and chalcogen variations of different suites of <span class="hlt">lherzolites</span> likely reflect different extents of reactive melt infiltration in mantle peridotites, with partial re-equilibration and melt extraction in open system environments. However, the variable re-equilibration of BM and BD <span class="hlt">lherzolites</span> apparently did not produce significant differences in HSE ratios such as Os/Ir, Ru/Ir, Rh/Ir, and Pd/Pt, which are in the range of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1999Tectp.306..199N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1999Tectp.306..199N"><span id="translatedtitle">Deep crustal structure off Akita, eastern margin of the Japan Sea, deduced from ocean bottom seismographic measurements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nishizawa, Azusa; Asada, Akira</p> <p>1999-06-01</p> <p>A seismic exploration was carried out to detect the heterogeneity of the seismic wavespeed structure associated with the plate convergence at the eastern margin of the Japan Sea. Two airgun-OBS (ocean bottom seismograph) profiles were shot off Akita, Japan, where a seismic gap seems to exist but the location of the plate boundary has not been confirmed. One of the profiles was 60 km long, trending NNE-SSW, named Line OBS-9, at the northeastern end of the <span class="hlt">Yamato</span> Basin and the other was 170 km long, trending WNW-ESE, Line NT95-1, parallel to the direction of the supposed plate convergence. The crustal structure beneath Line OBS-9 consists of six layers. The uppermost layer is sediment. Three layers are identified beneath the top sedimentary layer and their P wavespeeds are estimated to be 3.3-3.4 km/s, 5.1-5.4 km/s and 5.8-6.3 km/s, which corresponds to the upper crust. Underneath these layers, a layer with P wavespeed ranges of 6.3-7.2 km/s comprises the middle and lower crust. The depth of Moho is inferred to be 19 km. These wavespeed values are comparable with those of the present Japanese island arc, while the thickness of the crust is one-half of that of the Japanese arc. The crustal model supports the scenario that the <span class="hlt">Yamato</span> Basin is formed by extension of the island arc. The crustal model for Line NT95-1 shows a transition from the extended island arc structure beneath the <span class="hlt">Yamato</span> Basin to a thicker crust similar to the Japanese arc. P wavespeed heterogeneity related to the plate boundary is not detected. However, a significant change in the structural model along the profile is found around the region where the largest change in the seafloor topography exists. In that region, the wavespeeds in the middle crust have lower values than those of the neighboring area and the Moho begins to deepen towards the Japanese island arc. From comparison with the relationship between P wavespeed structure and aftershock distribution of the 1993 Hokkaido</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3076842','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3076842"><span id="translatedtitle">Natural dissociation of olivine to (Mg,Fe)SiO3 perovskite and magnesiowüstite in a shocked Martian meteorite</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Miyahara, Masaaki; Ohtani, Eiji; Ozawa, Shin; Kimura, Makoto; El Goresy, Ahmed; Sakai, Takeshi; Nagase, Toshiro; Hiraga, Kenji; Hirao, Naohisa; Ohishi, Yasuo</p> <p>2011-01-01</p> <p>We report evidence for the natural dissociation of olivine in a <span class="hlt">shergottite</span> at high-pressure and high-temperature conditions induced by a dynamic event on Mars. Olivine (Fa34-41) adjacent to or entrained in the shock melt vein and melt pockets of Martian meteorite olivine-phyric <span class="hlt">shergottite</span> Dar al Gani 735 dissociated into (Mg,Fe)SiO3 perovskite (Pv)+magnesiowüstite (Mw), whereby perovskite partially vitrified during decompression. Transmission electron microscopy observations reveal that microtexture of olivine dissociation products evolves from lamellar to equigranular with increasing temperature at the same pressure condition. This is in accord with the observations of synthetic samples recovered from high-pressure and high-temperature experiments. Equigranular (Mg,Fe)SiO3 Pv and Mw have 50–100 nm in diameter, and lamellar (Mg,Fe)SiO3 Pv and Mw have approximately 20 and approximately 10 nm in thickness, respectively. Partitioning coefficient, KPv/Mw = [FeO/MgO]/[FeO/MgO]Mw, between (Mg,Fe)SiO3 Pv and Mw in equigranular and lamellar textures are approximately 0.15 and approximately 0.78, respectively. The dissociation of olivine implies that the pressure and temperature conditions recorded in the shock melt vein and melt pockets during the dynamic event were approximately 25 GPa but 700 °C at least. PMID:21444781</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/1036314','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/1036314"><span id="translatedtitle">Unusual Iron Redox Systematics of Martian Magmas</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Danielson, L.; Righter, K.; Pando, K.; Morris, R.V.; Graff, T.; Agresti, D.; Martin, A.; Sutton, S.; Newville, M.; Lanzirotti, A.</p> <p>2012-03-26</p> <p>Martian magmas are known to be FeO-rich and the dominant FeO-bearing mineral at many sites visited by the Mars Exploration rovers (MER) is magnetite. Morris et al. proposed that the magnetite appears to be igneous in origin, rather than of secondary origin. However, magnetite is not typically found in experimental studies of martian magmatic rocks. Magnetite stability in terrestrial magmas is well understood, as are the stabilities of FeO and Fe{sub 2}O{sub 3} in terrestrial magmas. In order to better understand the variation of FeO and Fe{sub 2}O{sub 3}, and the stability of magnetite (and other FeO-bearing phases) in martian magmas, we have undertaken an experimental study with two emphases. First, we determine the FeO and Fe{sub 2}O{sub 3} contents of super- and sub-liquidus glasses from a <span class="hlt">shergottite</span> bulk composition at 1 bar to 4 GPa, and variable fO{sub 2}. Second, we document the stability of magnetite with temperature and fO{sub 2} in a <span class="hlt">shergottite</span> bulk composition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19930022752&hterms=Igneous+rocks&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3D%2528Igneous%2Brocks%2529','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19930022752&hterms=Igneous+rocks&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3D%2528Igneous%2Brocks%2529"><span id="translatedtitle">On the weathering of Martian igneous rocks</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Dreibus, G.; Waenke, H.</p> <p>1992-01-01</p> <p>Besides the young crystallization age, one of the first arguments for the martian origin of <span class="hlt">shergottite</span>, 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 <span class="hlt">shergottite</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19910057730&hterms=redox+reactions&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dredox%2Breactions','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19910057730&hterms=redox+reactions&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dredox%2Breactions"><span id="translatedtitle">Moessbauer spectra of olivine-rich achondrites - Evidence for preterrestrial redox reactions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Burns, R. G.; Martinez, S. L.</p> <p>1991-01-01</p> <p>Moessbauer spectral measurements at 4.2 K were made on several ureilites and the two <span class="hlt">shergottites</span> found in Antarctica, as well as two ureilite falls, three SNC meteorite falls, and two finds in order to distinguish products of preterrestrial redox reactions from phases formed during oxidative weathering on the earth. The spectra indicated that several ureilites contain major proportions of metallic iron, much of which resulted from preterrestrial carbon-induced reduction of ferrous iron in the outermost 10-100 microns of olivine grains in contact with carbonaceous material in the ureilites. The cryptocrystalline nature of these Fe inclusions in olivine renders the metal extremely vulnerable to aerial oxidation, even in ureilites collected as falls. It is inferred that the nanophase ferric oxides or oxyhydroxides identified in Brachina and Lafayette were produced by terrestrial weather of olivines before the meteorites were found. The absence of goethite in two olivine-bearing Antarctic <span class="hlt">shergottites</span> suggests that the 2 percent ferric iron determined in their Moessbauer spectra also originated from oxidation on Mars.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19860010806','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19860010806"><span id="translatedtitle">Magnetism of nakhlites and chassignites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Cisowski, S. M.</p> <p>1985-01-01</p> <p>Hysteresis measurements on three <span class="hlt">shergottite</span> and two nakhlite meteorites indicate single domain grain size behavior for the highly shocked Shergotty, Zagami, and EETA 79001 meteorites, with more multidomain-like behavior for the unshocked Nakhla and Governador Valadares meteorites. High viscosity and initial susceptibility for Antarctic <span class="hlt">shergottite</span> ALHA 7705 indicate the presence of superparamagnetic grains in this specimen. Thermomagnetic analysis indicate Shergotty and Zagami as the least initially oxidized, while EETA 79001 appears to be the most oxidized. Cooling of the meteorite samples from high temperature in air results in a substantial increase in magnetization due to the production of magnetite through oxidation exsolution of titanomagnetite. However, vacuum heating substantially suppresses this process, and in the case of EETA 79001 and Nakhla, results in a rehomogenization of the titanomagnetite grains. Remanence measurements on several subsamples of Shergotty and Zagami meteorites reveal a large variation in intensity that does not seem related to the abundance of remanence carriers. The other meteorites carry only weak remanence, suggesting weak magnetizing fields as the source of their magnetic signal. The meteorites' weak field environment is consistent with Martian or asteroidal body origin but inconsistent with terrestrial origin.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013M%26PS...48.1919G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013M%26PS...48.1919G"><span id="translatedtitle">Opaque minerals, magnetic properties, and paleomagnetism of the Tissint Martian meteorite</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gattacceca, JéRôMe; Hewins, Roger H.; Lorand, Jean-Pierre; Rochette, Pierre; Lagroix, France; Cournède, CéCile; Uehara, Minoru; Pont, Sylvain; Sautter, Violaine; Scorzelli, Rosa. B.; Hombourger, Chrystel; Munayco, Pablo; Zanda, Brigitte; Chennaoui, Hasnaa; FerrièRe, Ludovic</p> <p>2013-10-01</p> <p>We present a description of opaque minerals, opaque mineral compositions, magnetic properties, and paleomagnetic record of the Tissint heavily shocked olivine-phyric <span class="hlt">shergottite</span> that fell to Earth in 2011. The magnetic mineralogy of Tissint consists of about 0.6 wt% of pyrrhotite and 0.1 wt% of low-Ti titanomagnetite (in the range ulvöspinel 3-15 magnetite 85-97). The titanomagnetite formed on Mars by oxidation-exsolution of ulvöspinel grains during deuteric alteration. Pyrrhotite is unusual, with respect to other <span class="hlt">shergottites</span>, for its higher Ni content and lower Fe content. Iron deficiency is attributed by an input of regolith-derived sulfur. This pyrrhotite has probably preserved a metastable hexagonal monosulfide solution structure blocked at temperature above 300 °C. The paleomagnetic data indicate that Tissint was magnetized following the major impact suffered by this rock while cooling at the surface of Mars from a post-impact equilibrium temperature of approximately 310 °C in a stable magnetic field of about 2 µT of crustal origin. Tissint is too weakly magnetic to account for the observed magnetic anomalies at the Martian surface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/24740066','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24740066"><span id="translatedtitle">Isotopic links between atmospheric chemistry and the deep sulphur cycle on Mars.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Franz, Heather B; Kim, Sang-Tae; Farquhar, James; Day, James M D; Economos, Rita C; McKeegan, Kevin D; Schmitt, Axel K; Irving, Anthony J; Hoek, Joost; Dottin, James</p> <p>2014-04-17</p> <p>The geochemistry of Martian meteorites provides a wealth of information about the solid planet and the surface and atmospheric processes that occurred on Mars. The degree to which Martian magmas may have assimilated crustal material, thus altering the geochemical signatures acquired from their mantle sources, is unclear. This issue features prominently in efforts to understand whether the source of light rare-earth elements in enriched <span class="hlt">shergottites</span> lies in crustal material incorporated into melts or in mixing between enriched and depleted mantle reservoirs. Sulphur isotope systematics offer insight into some aspects of crustal assimilation. The presence of igneous sulphides in Martian meteorites with sulphur isotope signatures indicative of mass-independent fractionation suggests the assimilation of sulphur both during passage of magmas through the crust of Mars and at sites of emplacement. Here we report isotopic analyses of 40 Martian meteorites that represent more than half of the distinct known Martian meteorites, including 30 <span class="hlt">shergottites</span> (28 plus 2 pairs, where pairs are separate fragments of a single meteorite), 8 nakhlites (5 plus 3 pairs), Allan Hills 84001 and Chassigny. Our data provide strong evidence that assimilation of sulphur into Martian magmas was a common occurrence throughout much of the planet's history. The signature of mass-independent fractionation observed also indicates that the atmospheric imprint of photochemical processing preserved in Martian meteoritic sulphide and sulphate is distinct from that observed in terrestrial analogues, suggesting fundamental differences between the dominant sulphur chemistry in the atmosphere of Mars and that in the atmosphere of Earth. PMID:24740066</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20060022081','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20060022081"><span id="translatedtitle">Sm-Nd Age and Nd- and Sr- Isotopic Evidence for the Petrogenesis of Dhofar 378</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nyquist, L. E.; Ikeda, Y.; Shih, C.-Y.; Reese, Y. D.; Nakamura, N.; Takeda, H.</p> <p>2006-01-01</p> <p>Dhofar 378 (hereafter Dho 378) is one of the most ferroan lithologies among martian meteorites, resembling the Los Angeles basaltic <span class="hlt">shergottite</span> in lithology and mineral chemistry, although it is more highly shocked than Los Angeles. All plagioclase (Pl) grains in the original lithology were melted by an intense shock in the range 55-75 GPa. Clinopyroxenes (Cpx) sometimes show mosaic extinction under a microscope showing that they, too, experienced intense shock. Nevertheless, they zone from magnesian cores to ferroan rims, reflecting the original lithology. Cpx grains also often contain exsolution lamellae, showing that the original lithology cooled slowly enough for the lamellae to form. Because all plagioclase grains were melted by the intense shock and subsequently quenched, the main plagioclase component is glass (Pl-glass) rather than maskelynite. Like Los Angeles, but unlike most basaltic <span class="hlt">shergottites</span>, Dho 378 contains approximately equal modal abundances of Cpx and Pl-glass. The grain sizes of the original minerals were comparatively large (approximately 1 mm). The original plagioclase zoning has been severely modified. Following shock melting, the plagioclase melts crystallized from the outside inward, first forming outer rims of Cpx-Pl intergrowths (approximately 10 micrometers) followed by inner rims (10's to 100 micrometers) of An(sub 40-50) feldspar, and finally Pl-gl cores of compositions An(sub 33-50) with orthoclase compositions up to Or(sub 12).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080026133','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080026133"><span id="translatedtitle">Rb-Sr and Sm-Nd Isotopic Studies of Antarctic Nakhlite MIL 03346</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Shih, C.-Y.; Nyquist, L. E.; Reese, Y.</p> <p>2006-01-01</p> <p>Nakhlites are olivine-bearing clinopyroxenites with cumulate textures, and probably came from Mars [e.g., 1]. A total of seven nakhlites have been identified so far. Unlike other martian meteorites (e.g., <span class="hlt">shergottites</span>), nakhlites have been only moderately shocked and their original igneous textures are still well-preserved. Also, these meteorites have similarly older crystallization ages of approx.1.3 Ga compared to <span class="hlt">shergottites</span> with ages of approx.0.18-0.57 Ga [e.g., 2]. MIL 03346 is characterized by abundant (approx.20 vol %) glassy mesostasis, indicating that it cooled rapidly and probably formed near the top [3] or at the bottom [4] of the chilled margin of a thick intrusive body. The mesostasis quenched from the trapped intercumulus liquid may provide information on the parent magma compositions of the nakhlites. In this report, we present Rb-Sr and Sm-Nd isotopic data for MIL 03346, discuss correlation of its age with those of other nakhlites and the nature of their source regions in the Martian mantle.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080012523','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080012523"><span id="translatedtitle">Prospects for Chronological Studies of Martian Rocks and Soils</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nyquist, L. E.; Shih, C-Y.; Reese, Y. D.</p> <p>2008-01-01</p> <p>Chronological information about Martian processes comes from two sources: Crater-frequency studies and laboratory studies of Martian meteorites. Each has limitations that could be overcome by studies of returned Martian rocks and soils. Chronology of Martian volcanism: The currently accepted chronology of Martian volcanic surfaces relies on crater counts for different Martian stratigraphic units [1]. However, there is a large inherent uncertainty for intermediate ages near 2 Ga ago. The effect of differing preferences for Martian cratering chronologies [1] is shown in Fig. 1. Stoeffler and Ryder [2] summarized lunar chronology, upon which Martian cratering chronology is based. Fig. 2 shows a curve fit to their data, and compares to it a corresponding lunar curve from [3]. The radiometric ages of some lunar and Martian meteorites as well as the crater-count delimiters for Martian epochs [4] also are shown for comparison to the craterfrequency curves. Scaling the Stoeffler-Ryder curve by a Mars/Moon factor of 1.55 [5] places Martian <span class="hlt">shergottite</span> ages into the Early Amazonian to late Hesperian epochs, whereas using the lunar curve of [3] and a Mars/Moon factor 1 consigns the <span class="hlt">shergottites</span> to the Middle-to-Late Amazonian, a less probable result. The problem is worsened if a continually decreasing cratering rate since 3 Ga ago is accepted [6]. We prefer the adjusted St ffler-Ryder curve because it gives better agreement with the meteorite ages (Fig.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110005444','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110005444"><span id="translatedtitle">Effect of Sulfur on Siderophile Element Partitioning Between Olivine and Martian Primary Melt</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Usui, T.; Shearer, C. K.; Righter, K.; Jones, J. H.</p> <p>2011-01-01</p> <p>Since olivine is a common early crystallizing phase in basaltic magmas that have produced planetary and asteroidal crusts, a number of experimental studies have investigated elemental partitioning between olivine and silicate melt [e.g., 1, 2, 3]. In particular, olivine/melt partition coefficients of Ni and Co (DNi and DCo) have been intensively studied because these elements are preferentially partitioned into olivine and thus provide a uniquely useful insight into the basalt petrogenesis [e.g., 4, 5]. However, none of these experimental studies are consistent with incompatible signatures of Co [e.g., 6, 7, 8] and Ni [7] in olivines from Martian meteorites. Chemical analyses of undegassed MORB samples suggest that S dissolved in silicate melts can reduce DNi up to 50 % compared to S-free experimental systems [9]. High S solubility (up to 4000 ppm) for primitive <span class="hlt">shergottite</span> melts [10] implies that S might have significantly influenced the Ni and Co partitioning into <span class="hlt">shergottite</span> olivines. This study conducts melting experiments on Martian magmatic conditions to investigate the effect of S on the partitioning of siderophile elements between olivine and Martian primary melt.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1985RvGeo..23..391M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1985RvGeo..23..391M"><span id="translatedtitle">SNC meteorites - Clues to Martian petrologic evolution?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>McSween, H. Y.</p> <p>1985-11-01</p> <p><span class="hlt">Shergottites</span>, nakhlites and the Chassigny meteorites (SNC group) may have originated on Mars. The <span class="hlt">shergottites</span> are medium-grained basalts, the nakhlites are pyroxenites and the Chassigny is a dunite. The SNC group is petrologically diverse but differs from all other known achondrites in terms of mineral chemistry, the redox state, the oxygen isotopic composition and the radiometric ages. The SNC stones are mafic and ultramafic cumulate rocks with mineralogies that indicate rapid cooling and crystallization from tholeiitic magmas which contained water and experienced a high degree of oxidation. The characteristics suggest formation from a large parent body, i.e., a planet, but not earth. The estimated ages for the rocks match the estimated ages for several mapped Martian volcanoes in the Tharsis region. Additionally, the elemental and isotopic abundances of atmospheric gases embedded in melts in the SNC stones match Viking Lander data for the Martian atmosphere. However, reasons are cited for discounting the possibility that a large meteorite(s) collided with Mars about 180 myr ago and served as the mechanism for ejecting the SNC stones to earth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110022974','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110022974"><span id="translatedtitle">Iron Redox Systematics of Martian Magmas</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Righter, K.; Danielson, L.; Martin, A.; Pando, K.; Sutton, S.; Newville, M.</p> <p>2011-01-01</p> <p>Martian magmas are known to be FeO-rich and the dominant FeO-bearing mineral at many sites visited by the Mars Exploration rovers (MER) is magnetite [1]. Morris et al. [1] propose that the magnetite appears to be igneous in origin, rather than of secondary origin. However, magnetite is not typically found in experimental studies of martian magmatic rocks [2,3]. Magnetite stability in terrestrial magmas is well understood, as are the stability of FeO and Fe2O3 in terrestrial magmas [4,5]. In order to better understand the variation of FeO and Fe2O3, and the stability of magnetite (and other FeO-bearing phases) in martian magmas we have undertaken an experimental study with two emphases. First we document the stability of magnetite with temperature and fO2 in a <span class="hlt">shergottite</span> bulk composition. Second, we determine the FeO and Fe2O3 contents of the same <span class="hlt">shergottite</span> bulk composition at 1 bar and variable fO2 at 1250 C, and at variable pressure. These two goals will help define not only magnetite stability, but pyroxene-melt equilibria that are also dependent upon fO2.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120001839','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120001839"><span id="translatedtitle">Unusual Iron Redox Systematics of Martian Magmas</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Danielson, L.; Righter, K.; Pando, K.; Morris, R. V.; Graff, T.; Agresti, D.; Martin, A.; Sutton, S.; Newville, M.; Lanzirotti, A.</p> <p>2012-01-01</p> <p>Martian magmas are known to be FeO-rich and the dominant FeO-bearing mineral at many sites visited by the Mars Exploration rovers (MER) is magnetite. Morris et al. proposed that the magnetite appears to be igneous in origin, rather than of secondary origin. However, magnetite is not typically found in experimental studies of martian magmatic rocks. Magnetite stability in terrestrial magmas is well understood, as are the stabilities of FeO and Fe2O3 in terrestrial magmas. In order to better understand the variation of FeO and Fe2O3, and the stability of magnetite (and other FeO-bearing phases) in martian magmas, we have undertaken an experimental study with two emphases. First, we determine the FeO and Fe2O3 contents of super- and sub-liquidus glasses from a <span class="hlt">shergottite</span> bulk composition at 1 bar to 4 GPa, and variable fO2. Second, we document the stability of magnetite with temperature and fO2 in a <span class="hlt">shergottite</span> bulk composition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20160003883','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20160003883"><span id="translatedtitle">The Germanium Dichotomy in Martian Meteorites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Humayun, M.; Yang, S.; Righter, K.; Zanda, B.; Hewins, R. H.</p> <p>2016-01-01</p> <p>Germanium is a moderately volatile and siderophile element that follows silicon in its compatibility during partial melting of planetary mantles. Despite its obvious usefulness in planetary geochemistry germanium is not analyzed routinely, with there being only three prior studies reporting germanium abundances in Martian meteorites. The broad range (1-3 ppm) observed in Martian igneous rocks is in stark contrast to the narrow range of germanium observed in terrestrial basalts (1.5 plus or minus 0.1 ppm). The germanium data from these studies indicates that nakhlites contain 2-3 ppm germanium, while <span class="hlt">shergottites</span> contain approximately 1 ppm germanium, a dichotomy with important implications for core formation models. There have been no reliable germanium abundances on chassignites. The ancient meteoritic breccia, NWA 7533 (and paired meteorites) contains numerous clasts, some pristine and some impact melt rocks, that are being studied individually. Because germanium is depleted in the Martian crust relative to chondritic impactors, it has proven useful as an indicator of meteoritic contamination of impact melt clasts in NWA 7533. The germanium/silicon ratio can be applied to minerals that might not partition nickel and iridium, like feldspars. We report germanium in minerals from the 3 known chassignites, 2 nakhlites and 5 <span class="hlt">shergottites</span> by LAICP- MS using a method optimized for precise germanium analysis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20070007301','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20070007301"><span id="translatedtitle">Oxidation State of Nakhlites as inferred from Fe-Ti oxide Equilibria and Augite/Melt Europium Partitioning</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Makishima, J.; McKay, G.; Le, L.; Miyamoto, M.; Mikouchi, T.</p> <p>2007-01-01</p> <p>Recent studies have shown that Martian magmas had wide range of oxygen fugacities (fO2) and that this variation is correlated with the variation of La/Yb ratio and isotopic characteristics of the Martian basalts, <span class="hlt">shergottite</span> meteorites. The origin of this correlation must have important information about mantle sources and Martian evolution. In order to understand this correlation, it is necessary to know accurate value of oxidation state of other Martian meteorite groups. Nakhlites, cumulate clinopyroxenites, are another major group of Martian meteorites and have distinctly different trace element and isotopic characteristics from <span class="hlt">shergottites</span>. Thus, estimates of oxidation state of nakhlites will give us important insight into the mantle source in general. Several workers have estimated oxidation state of nakhlites by using Fe-Ti oxide equilibrium. However, Fe-Ti oxides may not record the oxidation state of the parent melt of the nakhlite because it is a late-stage mineral. Furthermore, there is no comprehensive study which analyzed all nakhlite samples at the same time. Therefore, in this study (1) we reduced the uncertainty of the estimate using the same electron microprobe and the same standards under the same condition for Fe-Ti oxide in 6 nakhlites and (2) we also performed crystallization experiments to measure partition coefficients of Eu into pyroxene in the nakhlite system in order to estimate fO2 when the pyroxene core formed (i.e. Eu oxybarometer [e.g. 2,6]).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFMMR13B1678M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFMMR13B1678M"><span id="translatedtitle">Shock Recovery and Heating Experiments on Baddeleyite: Implications for U-Pb Isotopic Systematics of Martian Meteorites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Misawa, K.; Niihara, T.; Kaiden, H.; Sekine, T.; Mikouchi, T.</p> <p>2009-12-01</p> <p>Introduction: Radiometric ages of Martian meteorites, <span class="hlt">shergottites</span> are generally young (i.e., ~165-475 Ma), and are in the late Amazonian chronostratigraphic unit [1]. Bouvier et al. [2-4] reported ~4.1-4.3 Ga old Pb-Pb ages for <span class="hlt">shergottites</span>, and suggested that young Rb-Sr, Sm-Nd, and Lu-Hf ages so far obtained were affected by alteration of phosphates, interaction with Martian subsurface fluids, or intense shock metamorphism. Baddeleyite (ZrO2) with apparently primary igneous morphology is an important phase in <span class="hlt">shergottites</span> for U-Pb age determination. In order to investigate shock effects on U-Pb isotopic systematics of baddeleyite, we undertook shock recovery and heating experiments on baddeleyite. Experimental: We used coarse-grained baddeleyite from Phalaborwa for a starting material. The baddeleyite was mixed with a coarse-grained terrestrial basalt with a weight ratio of 1:2. Shock-recovery experiments were performed using a propellant gun at NIMS [5]. The run products were placed in a vertical gas-mixing furnace and heated for 1-3 h at 1000-1300oC under log fO2 of IW+2.5 at 105 Pa. Textures were observed by a scanning electron microprobe and Raman spectra of shocked baddeleyite were obtained. In situ U-Th-Pb isotopic analysis was carried out with the SHRIMP II at NIPR [6]. Results and Discussion: We observed Raman peak shifts of 2-4 cm-1 in the 34-57 GPa samples. Lead loss from baddeleyite was not observed for the experimentally shocked samples. In addition, the U-Pb and Pb-Pb ages of shocked and heated baddeleyites are indistinguishable from those of unshocked baddeleyite within errors except minor lead loss from the baddeleyite shocked at 57 GPa and heated for 1 h at 1300oC. Although duration of peak shock-pressure and grain size of baddeleyite are different from the nature of basaltic <span class="hlt">shergottites</span>, our experimental results suggest that it is hard to completely reset U-Pb isotopic systematics of baddeleyite in Martian meteorite by shock events below ~60</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.V43A2825T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.V43A2825T"><span id="translatedtitle">Comparing Mantle Xenoliths from Mount Taylor and Rio Puerco Necks, New Mexico: Evidence for Metasomatism</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Thomas, A. E.; Schmidt, M. E.; Schrader, C. M.; Crumpler, L. S.</p> <p>2012-12-01</p> <p>The Mount Taylor Volcanic Field (MTVF) is located along the Jemez Lineament at the south eastern margin of the Colorado Plateau in north western New Mexico. To learn about its underlying lithospheric mantle, we conducted a survey of xenoliths from basaltic vents peripheral to the Mount Taylor edifice and the Rio Puerco Volcanic Necks. A total of 89 thin sections (32 from Mount Taylor and 57 from Rio Puerco) were examined. The population of thin sections from Mount Taylor and Rio Puerco listed respectively is: 18 and 20 <span class="hlt">lherzolites</span>; 8 and 24 pyroxenites; 4 and 3 wehrlites; 1 and 6 dunites; and 1 and 4 harzburgites. Pyroxenite grain size ranged from 1 to 9 mm and <span class="hlt">lherzolite</span> grains were typically 0.5 to 2 mm. Spinels ranged in colour from dark green, brown to black and they were generally <1 mm and interstitially concentrated. Spinel concentrations between the two suites were comparable, with an average of 2.6% for Mount Taylor and 2.0% for Rio Puerco. The largest concentration of spinels was in a pyroxenite at 12.5% from Mount Taylor. Up to 5% primary calcite is present in the Rio Puerco suite; in contrast calcite has not been identified in the Mount Taylor suite. Calcite grains were <0.5 mm in size and located at grain boundaries and as inclusions in clinopyroxene and orthopyroxene. Equilibrium textures include triple junction grain boundaries between olivines and clinopyroxenes in some <span class="hlt">lherzolites</span>. Disequilibrium textures include rounded, optically continuous olivine and orthopyroxene in clinopyroxene, complex intergrowths between clinopyroxene and orthopyroxene, and sheared olivine. Electron microprobe analyses were performed on 9 representative thin sections with 5 pyroxenites, 4 <span class="hlt">lherzolites</span> and 1 wehrlite; samples included green, brown, red and black spinels. Pyroxenes for the two suites decrease in Cr2O3 and increase in Al2O3 with decreasing Mg numbers, increase in CaO with decreasing MgO and increase in Na2O with increasing Al2O3. The presence of optically</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..1611589S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..1611589S"><span id="translatedtitle">Pyroxenites - Melting or Migration?: Evidence from the Balmuccia massif</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sossi, Paolo; O'Neill, Hugh</p> <p>2014-05-01</p> <p>The recognition of pyroxenites in the mantle, combined with their lower solidus temperatures than peridotite, have been proposed as contributors to melting (Pertermann and Hirschmann, 2003; Sobolev et al, 2005; 2007). Geochemical fingerprints of this process invoke an unspecified 'pyroxenite' as the putative source. In reality, mantle pyroxenites are diverse (Downes, 2007), requiring that their mode of origin and compositional variability be addressed. Due to the excellent preservation and exposure of the Balmuccia massif, it has become an archetype for orogenic peridotites, providing information on their composition, field relationships and metamorphic history (Shervais and Mukasa, 1991; Hartmann and Wedepohl, 1993; Rivalenti et al., 1995; Mazzucchelli et al., 2009). The Balmuccia massif consists of fertile <span class="hlt">lherzolite</span> with subordinate harzburgite and dunite and is riddled with pyroxenite bands, which fall into two suites - Chrome-Diopside (Cr-Di) and Aluminous-Augite (Al-Aug), a pairing present in most massif peridotites. Two-pyroxene thermometry gives temperatures of 850±25°C at 1-1.5 GPa, 500°C lower than asthenospheric mantle at that pressure, meaning they do not preserve their original, high temperature mineralogy. Decimetre-sized Cr-Di bands (≡75% CPX, 25% OPX) occur as initially Ol-free and bound by refractory dunite, but, as the bands are rotated into the plane of foliation, they mechanically incorporate olivine. Al-Aug veins (60% CPX, 25% OPX, 15% Sp) discordantly cut the body, intruding <span class="hlt">lherzolites</span> which show enrichments in Fe, Al and Ti adjacent to the dykes. Both the Cr-Di suite and the Al-Aug series have indistinguishable Sr-, Nd-isotopic compositions to the host peridotite (Mukasa and Shervais, 1999). The major element compositions of pyroxenes in the Cr-Di bands and those in the surrounding peridotites are identical. Together with isotopic evidence, this suggests a local source, not only chemically but spatially, where a very low degree melt (</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..15.9134A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15.9134A"><span id="translatedtitle">Evolution of mantle column beneath Bartoy volcanoes.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ashchepkov, Igor; Karmanov, Nikolai; Kanakin, Sergei; Ntaflos, Theodoros</p> <p>2013-04-01</p> <p>Pleistocene Bartoy volcanoes 1.5-0.8 Ma (Ashchepkov et al., 2003) represent variable set of hydrous cumulates and megacrysts and peridotite mantle xenoliths from spinel facies (Ashchepkov, 1991; Ionov, Kramm, 1992). Hydrous peridotites give series of the temperature groups: 1) deformed Fe - <span class="hlt">lherzolites</span> (1200-1100o) , 2) Phl porhyroclastiμ (1100-1020o), 3) Amph -Phl (1020-940o), 4) Dry protogranular (1020-940o), 5)Amph equigranular (940-880o) and 6) dry and fine grained (880-820o). and Fe-rich poikilitic (700-600o) (Ashchepkov, 1991). T according (Nimis, Taylor, 2000) The sequence of the megacrysts crystallized on the wall of basaltic feeder in pre - eruption stage is starting from HT dark green websterites (1300-1200o), black Cpx- Gar varieties (1250-1200o) evolved to Phl -CPx (1200-1130o) and Cpx - Kaers (1130-1020o) - Cpx low in TiO2., Ilm and San (<1000o) like in Vitim (Ashchepkov et la., 2011). The differentiation trends looks branched but the question if they. Differentiation ain relatively large magma bodies p produced Ga- Cpx (+Amph-Phl- Ilm +-San) and then Cpx-Gar -Pl cumulates in( ~8-12 kbar) interval. In the ToC-Fe# diagram the Intermediate trend between <span class="hlt">lherzolites</span> and megacrysts sub parallel to <span class="hlt">lherzolitic</span> is correspondent to the fractionation of the hydrous alkali basalt melts in vein network created from the highly H2O bearing basaltic derivates formed in intermediate magma chambers. The interaction of the peridotites with the pulsing rising and evolving basaltic system produced the wall rock metasomatism and separate groups of peridotites in different levels of mantle column. PT calculations show two PT path and probably melt intrusion events. Trace elements in glass from crystalline basalts show Zr, Pb dips and Ta, Nb, Sr enrichment for the black megacrystalline Cpx , Gar series. They show link with evolved basalts by HFSE, Ba enrichment but Cpx from kaersutite and further Gar - Cpx cumulates show depressions in Ta, Nb, Zr, and Pb moderate</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PCM....42...95G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PCM....42...95G"><span id="translatedtitle">Experimental petrology of peridotites, including effects of water and carbon on melting in the Earth's upper mantle</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Green, David H.</p> <p>2015-02-01</p> <p>For over 50 years, the use of high-pressure piston/cylinder apparatus combined with an increasing diversity of microbeam analytical techniques has enabled the study of mantle peridotite compositions and of magmas derived by melting in the upper mantle. The experimental studies have been guided by the petrology and geochemistry of peridotites from diverse settings and by the remarkable range of mantle-derived magma types. Recent experimental study using FTIR spectroscopy to monitor water content of minerals has shown that fertile <span class="hlt">lherzolite</span> (MORB-source upper mantle) at ~1,000 °C can store ~200 ppm H2O in defect sites in nominally anhydrous minerals (olivine, pyroxenes, garnet and spinel). Water in excess of 200 ppm stabilizes amphibole (pargasite) at P < 3 GPa up to the <span class="hlt">lherzolite</span> solidus. However, at P > 3 GPa, water in excess of 200 ppm appears as an aqueous vapour phase and this depresses the temperature of the upper mantle solidus. Provided the uppermost mantle (lithosphere) has H2O < 4,000 ppm, the mantle solidus has a distinctive P, T shape. The temperature of the vapour- undersaturated or dehydration solidus is approximately constant at 1,100 °C at pressures up to ~3 GPa and then decreases sharply to ~1,010 °C. The strongly negative d T/d P of the vapour-undersaturated solidus of fertile <span class="hlt">lherzolite</span> from 2.8 to 3 GPa provides the basis for understanding the lithosphere/asthenosphere boundary. Through upward migration of near-solidus hydrous silicate melt, the asthenosphere becomes geochemically zoned with the `enriched' intraplate basalt source (>500 ppm H2O) overlying the `depleted' MORB source (~200 ppm H2O). From the study of primitive MOR picrites, the modern mantle potential temperature for MORB petrogenesis is ~1,430 °C. The intersection of the 1,430 °C adiabat with the vapour-saturated <span class="hlt">lherzolite</span> solidus at ~230 km suggests that upwelling beneath mid-ocean ridges begins around this depth. In intraplate volcanism, diapiric upwelling begins from</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014JPhCS.495a2016N&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014JPhCS.495a2016N&link_type=ABSTRACT"><span id="translatedtitle">Instantaneous and scale-versatile gourdron theory: pair momentum equation, quasi-stability concept, and statistical indeterminacy revealing masses of elementary, bio-molecular, and cosmic particles</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Naitoh, Ken</p> <p>2014-04-01</p> <p>Flexible particles, including hadrons, atoms, hydrated biological molecules, cells, organs containing water, liquid fuel droplets in engines, and stars commonly break up after becoming a gourd shape rather than that of a string; this leads to cyto-fluid dynamics that can explain the proliferation, differentiation, and replication of biomolecules, onto-biology that clarifies the relationship between information, structure, and function, and the gourd theory that clarifies masses, including quark-leptons and Plank energy. The masses are related to the super-magic numbers, including the asymmetric silver ratio and symmetric <span class="hlt">yamato</span> ratio, and reveal further mechanisms underlying symmetry breaking. This paper gives further theoretical basis and evidence, because the gourd theory reported previously is a little analogical and instinctive.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1982PolRe..25..178K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1982PolRe..25..178K"><span id="translatedtitle">Non-destructive measurements of cosmogenic Al-26, natural K-40 and fallout Cs-137 in Antarctic meteorites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Komura, K.; Tsukamoto, M.; Sakanoue, M.</p> <p>1982-12-01</p> <p>Non-destructive gamma-ray measurements have been made to determine cosmogenic Al-26, natural K-40 and fallout Cs-137 activities in 15 Antarctic meteorites (14 from <span class="hlt">Yamato</span> Mountains and 1 from Allan Hills). The Al-26 activities range from 72 to 29 dpm/kg. If it is assumed that the saturation activity of Al-26 in chondrites is 60, about 1/3 of the measured meteorites show the contents close to this value; however, the rest show lower values. A simple graphical method was applied to estimate the exposure and terrestrial ages based on Al-26 and Mn-53 data, and these ages are compared with exposure ages obtained by Ne-21 measurements. The results are generally consistent with the Ne-21 data. It must be noted that the Antarctic meteorites are highly contaminated with fallout Cs-137 derived from nuclear test explosions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20040062375&hterms=metamorphic+rock&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3D%2528metamorphic%2Brock%2529','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20040062375&hterms=metamorphic+rock&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3D%2528metamorphic%2Brock%2529"><span id="translatedtitle">Lunar and Planetary Science XXXV: Lunar Rocks from Outer Space</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2004-01-01</p> <p>The following topics were discussed: Mineralogy and Petrology of Unbrecciated Lunar Basaltic Meteorite LAP 02205; LAP02205 Lunar Meteorite: Lunar Mare Basalt with Similarities to the Apollo 12 Ilmenite Basalt; Mineral Chemistry of LaPaz Ice Field 02205 - A New Lunar Basalt; Petrography of Lunar Meteorite LAP 02205, a New Low-Ti Basalt Possibly Launch Paired with NWA 032; KREEP-rich Basaltic Magmatism: Diversity of Composition and Consistency of Age; Mineralogy of <span class="hlt">Yamato</span> 983885 Lunar Polymict Breccia with Alkali-rich and Mg-rich Rocks; Ar-Ar Studies of Dhofar Clast-rich Feldspathic Highland Meteorites: 025, 026, 280, 303; Can Granulite Metamorphic Conditions Reset 40Ar-39Ar Ages in Lunar Rocks? [#1009] A Ferroan Gabbronorite Clast in Lunar Meteorite ALHA81005: Major and Trace Element Composition, and Origin; Petrography of Lunar Meteorite PCA02007, a New Feldspathic Regolith Breccia; and Troilite Formed by Sulfurization: A Crystal Structure of Synthetic Analogue</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993Metic..28R.381K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993Metic..28R.381K"><span id="translatedtitle">Isotopically Anomalous Nitrogen in Unequilibrated Ordinary Chondrites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kiyota, K.; Sugiura, N.; Hashizume, K.</p> <p>1993-07-01</p> <p>Introduction: Presolar grains such as diamond, SiC, and graphite have been reported to have isotopically anomalous nitrogen [1-3]. Because of their stability to chemical treatment, they are relatively easily concentrated in laboratories. There are probably other, less-durable presolar materials in primitive meteorites. We have therefore been searching for such presolar grains in UOCs, using the nitrogen isotope ratio as an indicator. In fact, isotopically heavy nitrogen in <span class="hlt">Yamato</span> 74191 (LL3.7) and light nitrogen in ALHA 77214 (L3.4), which are not those of diamond, SiC, or graphite, have been reported [4]. Here, we report some other nitrogen isotope anomalies, especially light nitrogen found in many UOCs. Results and Discussion: Nitrogen and argon extracted by the stepped combustion method from 200 degrees C to 1200 degrees C every 100 degrees C are measured with a static QMS. ALHA 77278 (LL3.7), LEW 86018 (L3.1), and ALHA 77216 (H3.7/3.9) have isotopically heavy nitrogen. There is a possibility that these chondrites have solar nitrogen, because ALHA 77216 has a large amount of solar neon and ALHA 77278 has a small amount of solar neon. ALHA 78119 (L3.5) shows a similar degassing profile to ALHA 77214 [4]. Therefore, it may have the same carriers of anomalous nitrogen as ALHA 77214. Since Chainpur also has a similar degassing profile to ALHA 77214, although its light nitrogen abundance is smaller, it has probably the same nitrogen carrier. ALHA 78084 (H4), Grady (H3.7), and <span class="hlt">Yamato</span> 74024 (L3.8) have very small amounts of nitrogen, probably because of metamorphic loss, and their delta ^15N values are nearly 0 per mil. ALHA 81251 (H3.2/3.4) degasses isotopically light nitrogen and primordial ^36Ar around 1100 degrees C (see Fig. 1), and delta ^15N goes down to -60 per mil at this temperature. Nearly the same degassing profiles have been found in ALH 83007 (L3.2/3.5), ALH 83010 (L3.3), EET 83399 (L3.3), LEW 86022 (L3.2), <span class="hlt">Yamato</span> 791500, <span class="hlt">Yamato</span> 82038, and Mezo Madaras</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110020558','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110020558"><span id="translatedtitle">Mineralogy of Inverted Pigeonite and Plagioclase in Cumulate Eucrites Y-980433 and Y-980318 with Reference to Early Crust Formation of the Vesta-Like Body</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Takeda, H.; Ohtake, M.; Hiroi, T.; Nyquist, L. E.; Shih, C.-Y.; Yamaguchi, A.; Nagaoka, H.</p> <p>2011-01-01</p> <p>On July 16, the Dawn spacecraft became the first probe to enter orbit around asteroid 4 Vesta and will study the asteroid for a year before departing for Ceres. The Vesta-HED link is directly tied to the observed and inferred mineralogy of the asteroid and the mineralogy of the meteorites [1]. Pieters et al. [2] reported reflectance spectra of the <span class="hlt">Yamato</span>- (Y-)980318 cumulate eucrite as a part of their study on the Asteroid-Meteorite Links in connection with the Dawn Mission. Pyroxenes and calcic plagioclase are the dominant minerals present in HED meteorites and provide multiple clues about how the parent body evolved [1]. The differentiation trends of HED meteorites are much simpler than those of the lunar crust</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1991GeCoA..55.2453M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1991GeCoA..55.2453M"><span id="translatedtitle">Rare earth elements in Japan Sea sediments and diagenetic behavior of Ce/Ce∗: Results from ODP Leg 127</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Murray, Richard W.; Buchholtzten Brink, Marilyn R.; Brumsack, Hans J.; Gerlach, David C.; Russ, G. Price</p> <p>1991-09-01</p> <p>The relative effects of paleoceanographic and paleogeographic variations, sediment lithology, and diagenetic processes on the recorded rare earth element (REE) chemistry of Japan Sea sediments are evaluated by investigating REE total abundances and relative fractionations in 59 samples from Ocean Drilling Program Leg 127. REE total abundances (ΣREE) in the Japan Sea are strongly dependent upon the paleoceanographic position of a given site with respect to terrigenous and biogenic sources. REE concentrations at Site 794 (<span class="hlt">Yamato</span> Basin) overall correspond well to aluminosilicate chemical indices and are strongly diluted by SiO2 within the late Miocene-Pliocene diatomaceous sequence. Eu/Eu∗ values at Site 794 reach a maximum through the diatomaceous interval as well, most likely suggesting an association of Eu/Eu∗ with the siliceous component, or reflecting slight incorporation of a detrital feldspar phase. ΣREE at Site 795 (Japan Basin) also is affiliated strongly with aluminosilicate phases, yet is diluted only slightly by siliceous input. At Site 797 (<span class="hlt">Yamato</span> Basin), REE is not as clearly associated with the aluminosilicate fraction, is correlated moderately to siliceous input, and may be sporadically influenced by detrital heavy minerals originating from the nearby rifted continental fragment composing the <span class="hlt">Yamato</span> Rise. The biogenic influence is largest at Site 794, moderately developed at Site 797, and of only minor importance at Site 795, reflecting basinal contrasts in productivity such that the <span class="hlt">Yamato</span> Basin records greater biogenic input than the Japan Basin, while the most productive waters overlie the easternmost sequence of Site 794. Ce/Ce∗ profiles at all three sites increase monotonically with depth, and record progressive diagenetic LREE fractionation. The observed Ce/Ce∗ record does not respond to changes in oxygenation state of the overlying water, and Ce/Ce∗ correlates slightly better with depth than with age. The downhole increase in Ce</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19800039440&hterms=c4&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dc4','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19800039440&hterms=c4&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dc4"><span id="translatedtitle">Total carbon and sulfur abundances in Antarctic meteorites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gibson, E. K., Jr.; Yanai, K.</p> <p>1979-01-01</p> <p>Total carbon and sulfur abundances have been measured in five Antarctic meteorites. Two C2 carbonaceous chondrites <span class="hlt">Yamato</span> 74662 and Allan Hills 77306 have sulfur abundances (3.490 plus or minus .040% and 3.863 plus or minus 0.050% respectively) similar to other C2 chondrites but their carbon abundances (1.514 plus or minus 0.050% and 1.324 plus or minus .040% respectively) are lower than previously measured C2 chondrites. The decreased carbon abundances may reflect the effects of weathering in cold environments. Carbon and sulfur abundances for one C4 carbonaceous chondrite, one E4 enstatite chondrite and one ureilite are similar to values reported previously for meteorites of the same petrologic grades.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19850035874&hterms=history+chemical&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dhistory%2Bchemical','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19850035874&hterms=history+chemical&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dhistory%2Bchemical"><span id="translatedtitle">Mineralogical comparison and cooling history of lunar and chondritic vesicular melt breccias</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Miyamoto, M.; Takeda, H.; Ishii, T.</p> <p>1984-01-01</p> <p>Lunar sample 77135, an impact melt breccia full of vesicles, has been reinvestigated by electron microprobe and X-ray diffraction techniques and compared with a vesicular melt LL chondrite, <span class="hlt">Yamato</span> 790964, in an attempt to understand their impact heating processes and subsequent cooling history. Notable similarities between the lunar and chondritic melt breccias include: abundant vesicles, similar pyroxene chemical zoning trends, the presence of variable amounts of clastic material, and similar chemical compositions except for K and Na contents of glass and mesostasis. Some constraints on the cooling history are estimated from Mg-Fe diffusion profiles in olivine and pyroxene. The burial depth of lunar sample 77135 during cooling was 0.2-100 m; the depth for the chondrite was probably smaller. Impact melts were probably produced and a layer of regolith retained on the parent body sufficiently thick to allow the olivines to homogenize during slow cooling.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19860049963&hterms=uranium+series+dating&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Duranium%2Bseries%2Bdating','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19860049963&hterms=uranium+series+dating&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Duranium%2Bseries%2Bdating"><span id="translatedtitle">Lunar and Planetary Science Conference, 16th, Houston, TX, March 11-15, 1985, Proceedings. Part 2</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ryder, G. (Editor)</p> <p>1986-01-01</p> <p>The present conference presents papers on the criteria, data and implications of pristine lunar glasses, lunar granulities and their precursor anorthositic norites of the early lunar crust, characterization and evidence for early formation in the megaregolith of Apollo 16 regolith breccias, and anorthosite assimilation and the origin of the Mg/Fe-related bimodality of pristine moon rocks in support of the magmasphere hypothesis. Other topics include the mineralogy of <span class="hlt">Yamato</span> 791073 with reference to crystal fractionation of the howardite parent body, the geology and geomorphology of the Venus surface as revealed by the radar images obtained by Veneras 15 and 16, tidal dissipation in a viscoelastic planet, and cosmogenic neutron-capture-produced nuclides in stony meteorites. Also considered are the first results of hydrous alteration of amorphous silicate smokes, elemental analysis of a comet nucleus by passive gamma ray spectrometry from a penetrator, and uranium series dating of Allan Hills ice.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20040056051&hterms=Dunite&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DDunite','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20040056051&hterms=Dunite&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DDunite"><span id="translatedtitle">Signatures in Martian Volatiles and the Magma Sources of NC Meteorites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Marti, K.; Mathew, K. J.</p> <p>2004-01-01</p> <p>We report nitrogen and xenon isotopic signatures in <span class="hlt">Yamato</span> nakhlites and use the data to assess properties of the magma source of NC meteorites in planet Mars. The Chassigny meteorite was investigated by Floran et al, who classified it as a cumulate dunite with hydrous amphibole-bearing melt inclusions with no preferred orientation of the olivines. Their inferred composition of the parent magma, which was based on electron microprobe analyses, has been questioned. The trace and minor elements in minerals were analyzed in nakhlites and in Chassigny and the authors conclude that nakhlites may represent samples from different horizons of the same lithologic unit, but that Chassigny was not co-magmatic with the nakhlites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19920033558&hterms=paleomagnetism&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dpaleomagnetism','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19920033558&hterms=paleomagnetism&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dpaleomagnetism"><span id="translatedtitle">Remanent magnetic properties of unbrecciated eucrites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Cisowski, Stanley M.</p> <p>1991-01-01</p> <p>This study examines the remanent magnetic properties of five unbrecciated eucrites, ranging from the coarse-grained cumulate Moore County to the quenched melt rock ALH 81001 in order to assess the strength of the magnetic field associated with their parent body during their formation. Two of the meteorites are judged as unlikely to have preserved their primary thermal remanence because of large variations in subsample remanence intensity and direction (Ibitira), and lack of NRM resistance to AF and thermal demagnetization (PCA 82502). The lack of a strong (greater than 0.01 mT) magnetizing field during their cooling on the eucrite parent body is inferred from the low normalized NRM intensities for subsamples of ALH 81001 and <span class="hlt">Yamato</span> 791195.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016MinPe.110...87G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016MinPe.110...87G"><span id="translatedtitle">Mineral associations and major element compositions of base metal sulphides from the subcontinental lithospheric mantle of NE Spain</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Galán, Gumer; Cruz, Erzika; Fernández-Roig, Mercè; Martínez, Francisco J.; Oliveras, Valentí</p> <p>2016-02-01</p> <p>This study deals with textural types and major element compositions of Cu-Ni-Fe sulphides from spinel <span class="hlt">lherzolite</span>, harzburgite and olivine websterite xenoliths found in alkali basaltic rocks of the Neogene-Quaternary volcanic zone of Catalonia (NE Spain). Sulphides in harzburgites and websterites are scarce. Four textural types have been distinguished: inclusions in silicates and spinel, trails of small droplets often radiating from inclusions, interstitial grains, and grains related to pyrometamorphic textures. The mineral associations are dominated by one or two low-temperature monosulphide solid solutions: mss1, mss2, occasionally accompanied by pyrrhotite, pentlandite and Cu-rich sulphides. Compositions of mss1 are more Fe-enriched in inclusions and interstitial grains than in grains related to pyrometamorphism. Compositions of mss2 are Ni-rich very close to pentlandite. Sulphide bulk compositions correspond to high-temperature monosulphide solid solution equilibrated with a relatively Cu-Ni enriched sulphide melt at 1100-1000 °C. The breakdown products of these earlier compositions could have been either equilibrated below 600, 300 °C or being at disequilibrium. A restitic origin is consistent with the main sulphide mineral associations, the estimated melt extraction for peridotites (<30 %) and with the fact that <span class="hlt">lherzolites</span> are less affected by cryptic metasomatism than harzburgites . However, Ni exchange coefficients between olivine and the high-temperature monosulphide solid solution underestimate equilibrium values. This suggests that some <span class="hlt">lherzolites</span> could derive from pervasive refertilization. The scarcity of sulphides in websterites is explained by S incompatible behaviour during the formation of earlier cumulates from the mafic alkaline magmas which caused the cryptic metasomatism.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016Litho.254...67E&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016Litho.254...67E&link_type=ABSTRACT"><span id="translatedtitle">The basaltic volcanism of the Dumisseau Formation in the Sierra de Bahoruco, SW Dominican Republic: A record of the mantle plume-related magmatism of the Caribbean Large Igneous Province</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Escuder-Viruete, Javier; Joubert, Marc; Abad, Manuel; Pérez-Valera, Fernando; Gabites, Janet</p> <p>2016-06-01</p> <p>The basaltic volcanism of the Dumisseau Fm in the Sierra de Bahoruco, SW Dominican Republic, offers the opportunity to study, on land, the volcanism of the Caribbean Large Igneous Province (CLIP). It consists of an at least 1.5 km-thick sequence of submarine basaltic flows and pyroclastic deposits, intruded by doleritic dykes and sills. Three geochemical groups have been identified: low-Ti tholeiites (group I); high-Ti transitional basalts (group II); and high-Ti and LREE-enriched alkaline basalts (group III). These geochemical signatures indicate a plume source for all groups of basalts, which are compositionally similar to the volcanic rocks that make up various CLIP fragments in the northern region of the Caribbean Plate. Trace element modelling indicates that group I magmas are products of 8-20% melting of spinel <span class="hlt">lherzolite</span>, group II magmas result 4-10% melting of a mixture of spinel and garnet <span class="hlt">lherzolite</span>, and group III basalts are derived by low degrees (0.05-4%) of melting of garnet <span class="hlt">lherzolite</span>. Dynamic melting models suggest that basalts represent aggregate melts produced by progressive decompression melting in a mantle plume. There is no compositional evidence for the involvement of a Caribbean supra-subduction zone mantle or crust in the generation of the basalts. Two 40Ar/39Ar whole-rock ages reflect the crystallisation of group II magmas at least in the late Campanian (~ 74 Ma) and the lower Eocene (~ 53 Ma). All data suggest that the Dumisseau Fm is an emerged fragment of the CLIP, which continues southward through the Beata Ridge</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PCM....42..143F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PCM....42..143F"><span id="translatedtitle">Novodneprite (AuPb3), anyuiite [Au(Pb, Sb)2] and gold micro- and nano-inclusions within plastically deformed mantle-derived olivine from the Lherz peridotite (Pyrenees, France): a HRTEM-AEM-EELS study</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ferraris, Cristiano; Lorand, Jean-Pierre</p> <p>2015-02-01</p> <p>To contribute the problem of the missing ("invisible") gold fraction in mantle rocks, olivine grains separated from orogenic <span class="hlt">lherzolite</span> of the peridotite body of Lherz (Eastern Pyrenees, France) have been investigated by transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS). The results indicate the presence of micrometric inclusions of novodneprite, AuPb3, and anyuiite, Au(Pb,Sb)2, together with nanometric clusters of metallic gold. Both minerals have been recognised on TEM images as darker contrast inclusions and identified through selected area electron diffraction (SAED) and energy dispersive spectroscopy (EDS) analyses. Gold clusters have been indirectly identified in randomly distributed nano-sized rectangular areas that occur in TEM images obtained from the edges of olivine crystals. Within these volumes the EDS analyses reveal a constant presence of Au (0.1-0.2 wt %). High-resolution TEM (HRTEM) investigations evidence series of regularly alternating sigmoidal and ellipsoidal domains developed along [110]. The EELS investigations revealed that the Au signal (M-series lines) arises from the ellipsoidal domains. It is proposed that novodneprite and anyuiite are the result of subsolidus recrystallization of the Pyrenean <span class="hlt">lherzolites</span> accompanied by a secondary olivine grains growth that trapped inter-granular components. Likely, a process of plastic deformation favoured the formation of edge dislocations within olivine grains and thus, the circulation through them of Au-enriched fluids. A mass balance calculation of the missing gold percentage within this <span class="hlt">lherzolite</span> points to olivine as one of the potential hosts for about the 80 % of the "invisible" gold in form of nano-inclusions, whereas only 20 % of the whole-rock Au-budget, would be hosted within assemblages of Cu-Fe-Ni sulphides.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009Litho.112..896K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009Litho.112..896K"><span id="translatedtitle">Nature and timing of multiple metasomatic events in the sub-cratonic lithosphere beneath Labait, Tanzania</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Koornneef, Janne M.; Davies, Gareth R.; Döpp, Sonja P.; Vukmanovic, Zoja; Nikogosian, Igor K.; Mason, Paul R. D.</p> <p>2009-11-01</p> <p>Petrography, mineral major- and trace element analyses and Rb-Sr and Sm-Nd systematics of xenoliths from Labait volcano, north-central Tanzania, document multiple metasomatic events after initial depletion of the Archaean sub-lithospheric mantle. Four distinct metasomatic phases occurred during the 2.8-3.2 Ga history of the mantle section of the Tanzanian craton. 1) Garnet and Cr-diopside in two depleted <span class="hlt">lherzolites</span> record LREE enrichment in an early cryptic metasomatic event (~ 2 Ga) resulting in unradiogenic ɛ Nd (- 6.6) and relatively radiogenic Sr signature ( 87Sr/ 86Sr = 0.7049); 2) Four texturally equilibrated peridotites contain phlogopite and Cr-diopside inferred to be introduced by a hydrous melt/fluid that produced LREE enrichment related to the subduction and collision during the 650 Ma Pan-African Orogeny; 3) Fe-enrichment is observed in many garnet-free wehrlites and dunites having low Mg# olivines. Timing of this enrichment event remains poorly defined; and 4) One spinel <span class="hlt">lherzolite</span> records orthopyroxene replacing clinopyroxene due to recent infiltration of a rift-related H 2O poor, K-alkaline silicate melt. This ongoing metasomatic reaction caused by rift-related magmatism would result in the conversion of <span class="hlt">lherzolite</span> to orthopyroxene-rich harzburgite. The reaction possibly represents the mechanism involved in the formation of orthopyroxene-rich sub-continental lithospheric mantle below the Kaapvaal and Siberian cratons. Generally, the rift-related metasomatism beneath Tanzania has caused formation of interstitial clinopyroxene, melt veins and melt pockets and new rims of phlogopite, all of which are in chemical disequilibrium with the original xenolith mineralogy.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..1513248P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..1513248P"><span id="translatedtitle">Wehrlitisation in the upper mantle beneath the Nógrád-Gömör Volcanic Field (Northern Pannonian Basin)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Patkó, Levente; Előd Aradi, László; Liptai, Nóra; Szabó, Csaba</p> <p>2013-04-01</p> <p>The Nógrád-Gömör Volcanic Field is situated in the northern part of the Pannonian Basin, where Plio-Pleistocene alkaline basalts brought upper mantle xenoliths to the surface. We collected great number of ultramafic xenoliths from the central part of the region, Medves-plateau (Eresztvény, Magyarbánya) and Baby hill (Ratka, Filakovske Kovace, Terbelovce), and detailed petrographic studies were carried out. As a result, beside the dominating <span class="hlt">lherzolite</span> xenoliths, large number of wehrlite xenoliths also appeared, in which the modal proportion of clinopyroxene was increased in contrast to the descending amount of ortopyroxene. These wehrlite xenoliths show very unique texture, which is characterized by irregularly shaped olivine grains hosted in clinopyroxene and vermicular spinel inclusions in clinopyroxenes. According to petrographic features, ten wehrlite xenoliths have been selected for a detailed study. Based on the major elements of rock forming minerals, Fe and Mn enrichment in olivines, Ti, Al and Fe enrichment in clinopyroxenes, and Fe and Ti enrichment in spinels can be observed compared to those of <span class="hlt">lherzolite</span> xenoliths. In the studied wehrlite xenoliths silicate, fluid and sulfide inclusions are also abundant. We focused on the latter ones in this thesis. The mineralogy of these multi-phase sulfides is in agreement with those usually found in the upper mantle with domination of pyrrhotite, pentlandite and chalcopyrite. However, bulk composition of the sulfides slightly differs from the <span class="hlt">lherzolite</span> xenoliths. Sulfides in wehrlite xenoliths show higher Fe and lower Cu concentrations. Based on our detailed petrography and geochemistry of rock forming constituents and sulfide minerals, wehrlite xenoliths are products of a process called stealth mantle metasomatism where new minerals, in our case clinopyroxene is introduced to the system that is mineralogically indistinguishable from common upper mantle peridotites. This metasomatism is supposed to be</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.V11D3088M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.V11D3088M"><span id="translatedtitle">Variably Depleted Peridotites from Loma Caribe (Dominican Republic): A Possible Record of Subduction Initiation beneath the Greater Antilles Paleo-Arc</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Marchesi, C.; Garrido, C. J.; Proenza, J. A.; Butjosa, L.; Lewis, J. F.</p> <p>2015-12-01</p> <p>Several mantle peridotite massifs crop out as isolated dismembered bodies in tectonic belts along the northern margin of the Caribbean plate. Among these bodies, the Loma Caribe peridotite forms the core of the Median Belt in central Dominican Republic. This peridotite massif is mainly composed of Cpx-bearing harzburgite, harzburgite, <span class="hlt">lherzolite</span> and (Opx-bearing) dunite, locally intruded by gabbroic rocks of Barremian age (~ 125 Ma). Mg# of olivine increases from lower values in <span class="hlt">lherzolite</span> (90), to higher values in Cpx-harzburgite (91), harzburgite (92) and dunite (92-94). Cr# of spinel spans from 0.23 in <span class="hlt">lherzolite</span> to 0.87 in dunite, and progressively increases from fertile to refractory lithologies. These variations overlap the mineral compositions of both abyssal and supra-subduction zone peridotites. The sample/chondrite REE concentrations of whole rocks are variable (0.002 < LREEN < 0.11 and 0.003 < HREEN < 1.02), and the HREE contents generally reflect the fertility of the samples. Similar to mineral chemistry, these trace element abundances overlap the compositions of both highly depleted supra-subduction and more fertile abyssal peridotites. Peridotites are variably enriched in the most incompatible and fluid-mobile trace elements (Cs, Rb, Ba, Th, U and Pb), and show negative anomalies of Nb and Ta. MREE/HREE fractionations in whole rocks and clinopyroxene support that these rocks are residues after initial fractional melting (~ 4%) in the garnet stability field and additional melting (~ 5-15%) in the spinel peridotite facies. The relative enrichment in incompatible and fluid-mobile elements (e.g., LILE and LREE) probably resulted from interaction of melting residues with ascending fluids/melts. We interpret the compositional variability of the Loma Caribe peridotite as reflecting different stages of generation of sub-oceanic mantle lithosphere during the Lower Cretaceous initiation of subduction beneath the Greater Antilles Paleo-arc.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.6385M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.6385M"><span id="translatedtitle">Geochemical composition of subcontinental lithospheric mantle in the westernmost Mediterranean: constrains from peridotite xenoliths in Plio-Pleistocene alkali basalts (eastern Betic Cordillera, SE Spain)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Marchesi, Claudio; Konc, Zoltán; Bosch, Delphine; Garrido, Carlos J.; Hidas, Károly; Varas-Reus, María Isabel</p> <p>2016-04-01</p> <p>Peridotite xenoliths in Plio-Pleistocene alkali basalts from the eastern Betic Cordillera (Murcia, SE Spain) provide key information on Alpine tectono-magmatic processes that affected the subcontinental lithospheric mantle beneath the westernmost Mediterranean. Here we present a detailed geochemical study comprising whole-rock and mineral major- and trace-element, as well as Sr-Nd-Pb isotopic compositional data of spinel ± plagioclase <span class="hlt">lherzolite</span>, spinel ± plagioclase harzburgite and spinel wehrlite xenoliths from Tallante and Los Perez volcanic centers. The whole-rock major element compositions and mineral chemistry of the studied xenoliths reflect increasing fertility from clinopyroxene-poor peridotites (Group I; Mg# up to 91.5), to common <span class="hlt">lherzolites</span> (Group II; Mg# up to 90.6), fertile <span class="hlt">lherzolites</span> (Group III; Mg# = 86.8-88.9) and wehrlites (Mg# = 86.7-87.4). The mineral major element chemistry records the geochemical imprint of maximum 10-12 % partial melting in the most depleted Group I peridotites. However, trace element and isotopic data attest for various degrees of metasomatic enrichment that overprinted the previously depleted lithospheric mantle. Interaction with melts produced enrichment of LREE in Group II and Group III peridotites, as well as in wehrlites. In contrast to major and trace elements, Sr-Nd-Pb radiogenic isotope systematic is unrelated to compositional groups and shows isotopic variations between DMM and EM2 end-members and contribution of an Atlantic sediment-like component. Different whole-rock trace element compositions coupled to similar isotopic signatures indicate that metasomatism was caused by external melt(s) issued from a common source not before the Tertiary. These geochemical evidences attest for the percolation of slab-derived, SiO2-undersaturated melts (and hydrous fluids) with carbonate sediment affinity in the pre-Miocene supra-subduction continental lithospheric mantle beneath the Alboran Basin.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.8766V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.8766V"><span id="translatedtitle">How mantle heterogeneity can affect geochemistry of magmas and their styles of emplacement: a fascinating tale revealed by Etna alkaline lavas</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Viccaro, Marco; Zuccarello, Francesco</p> <p>2016-04-01</p> <p>Geochemical investigations of Mt. Etna magmas have led to notable findings on the nature of compositional heterogeneity of the mantle source beneath the volcano. Some of the observed features explain the short-term geochemical variability of volcanic rocks erupted at Mt. Etna in recent times, which are characterized by increase of LILE, 87Sr/86Sr and decrease of 143Nd/144Nd, 206Pb/204Pb,176Hf/177Hf. This compositional behavior has not attributed exclusively to differentiation processes such as fractional crystallization, crustal assimilation and effects of volatile flushing. In this study, based on some geochemical similarities of the Etnean and Hyblean alkaline magmas, we have modeled partial melting of a composite source constituted by two rock types, inferred by various observations performed on some Hyblean xenoliths, namely: a spinel <span class="hlt">lherzolite</span> bearing phlogopite-amphibole and a garnet pyroxenite in form of veins intruded into <span class="hlt">lherzolite</span> that is interpreted as metasomatic high-temperature fluids (silicate melts) crystallized at mantle conditions. Partial melting modeling has been applied to each rock type and the resulting primary liquids have been then mixed in various proportions. The concentrations of major and trace elements along with the water obtained from the modeling are remarkably comparable with those of Etnean melts re-equilibrated at primary conditions. Different proportions of spinel <span class="hlt">lherzolite</span> bearing metasomatic phases and garnet pyroxenite can account for the signature of a large spectrum of Etnean alkaline magmas and for their geochemical variability through time. Our study implies that magmas characterized by variable compositions and volatile contents directly inherited from the source can undergo distinct histories of ascent and evolution in the plumbing system at crustal levels, potentially leading to a wide range of eruptive styles. A rather shallow source inferred from the model also excludes the presence of deep mantle structures</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014E%26PSL.397...80C&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014E%26PSL.397...80C&link_type=ABSTRACT"><span id="translatedtitle">Experimental melting of phlogopite-bearing mantle at 1 GPa: Implications for potassic magmatism</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Condamine, Pierre; Médard, Etienne</p> <p>2014-07-01</p> <p>We have experimentally investigated the fluid-absent melting of a phlogopite peridotite at 1.0 GPa (1000-1300 °C) to understand the source of K2O- and SiO2-rich magmas that occur in continental, post-collisional and island arc settings. Using a new extraction technique specially developed for hydrous conditions combined with iterative sandwich experiments, we have determined the composition of low- to high-degree melts (Φ=1.4 to 24.2 wt.%) of metasomatized <span class="hlt">lherzolite</span> and harzburgite sources. Due to small amounts of adsorbed water in the starting material, amphibole crystallized at the lowest investigated temperatures. Amphibole breaks down at 1050-1075 °C, while phlogopite-breakdown occurs at 1150-1200 °C. This last temperature is higher than the previously determined in a mantle assemblage, due to the presence of stabilizing F and Ti. Phlogopite-<span class="hlt">lherzolite</span> melts incongruently according to the continuous reaction: 0.49 phlogopite + 0.56 orthopyroxene + 0.47 clinopyroxene + 0.05 spinel = 0.58 olivine + 1.00 melt. In the phlogopite-harzburgite, the reaction is: 0.70 phlogopite + 1.24 orthopyroxene + 0.05 spinel = 0.99 olivine + 1.00 melt. The K2O content of water-undersaturated melts in equilibrium with residual phlogopite is buffered, depending on the source fertility: from ∼3.9 wt.% in <span class="hlt">lherzolite</span> to ∼6.7 wt.% in harzburgite. Primary melts are silica-saturated and evolve from trachyte to basaltic andesite (63.5-52.1 wt.% SiO2) with increasing temperature. Calculations indicate that such silica-rich melts can readily be extracted from their mantle source, due to their low viscosity. Our results confirm that potassic, silica-rich magmas described worldwide in post-collisional settings are generated by melting of a metasomatized phlogopite-bearing mantle in the spinel stability field.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMPP42C..08I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMPP42C..08I"><span id="translatedtitle">Mid-Miocene to Pleistocene Radiolarian fossil record from IODP Expedition 346: Faunal response to the global climatic changes and local/regional tectonics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Itaki, T.; Motoyama, I.; Kamikuri, S.; Tada, R.; Murray, R. W.; Alvarez Zarikian, C. A.</p> <p>2014-12-01</p> <p>It is well known that radiolarian fossils can be used as a geological tool for the age assignment and paleoceanographic reconstruction. In this study, we analyzed radiolarian fossils for seven drilled sites of IODP Exp. 346 from the Japan, <span class="hlt">Yamato</span> and Ulleung (JYU) basins in a marginal sea of the mid-latitude NW Pacific. Significant variations of the well-preserved fossil assemblage imply that the unique oceanic circulation changes in the basins through Mid-Miocene to Pleistocene might be controlled by global climatic changes and topographic changes with local/regional tectonics. Warm water radiolarians Dictyocoryne spp. and Tetrapyle spp. characterized in the Tsushima Current water occurred commonly since 1.7 Ma suggesting a beginning of the warm water inflow from the southern strait of the basins. It might be coincident with an opening of the Okinawa Trough in the East China Sea. On the other hand, during the Pliocene period, sporadic occurrence of the warm water species was recognized in southern part of the examined area. This implies that a minor influence of the warm water was present in the southern coastal area of the <span class="hlt">Yamato</span> Basin. Typical deep dwelling species such as Cornutella profunda and Peripyramis circumtexta is absent in the present JYU basins, however they occurred frequently during Pliocene and Miocene. This suggests the deep-water exchange between the JYU basins and the North Pacific via the deeper strait, which might be present in the northern part of the sea. These deep-water radiolarians disappeared from the JYU basins at the early Pleistocene (~2.7 Ma to 1.7 Ma), which is almost coincident with the Northern Hemisphere Glaciation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/12215642','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/12215642"><span id="translatedtitle">Diamond genesis, seismic structure, and evolution of the Kaapvaal-Zimbabwe craton.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Shirey, Steven B; Harris, Jeffrey W; Richardson, Stephen H; Fouch, Matthew J; James, David E; Cartigny, Pierre; Deines, Peter; Viljoen, Fanus</p> <p>2002-09-01</p> <p>The lithospheric mantle beneath the Kaapvaal-Zimbabwe craton of southern Africa shows variations in seismic P-wave velocity at depths within the diamond stability field that correlate with differences in the composition of diamonds and their syngenetic inclusions. Middle Archean mantle depletion events initiated craton keel formation and early harzburgitic diamond formation. Late Archean accretionary events involving an oceanic lithosphere component stabilized the craton and contributed a younger Archean generation of eclogitic diamonds. Subsequent Proterozoic tectonic and magmatic events altered the composition of the continental lithosphere and added new <span class="hlt">lherzolitic</span> and eclogitic diamonds to the Archean diamond suite. PMID:12215642</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JGeo...61..154S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JGeo...61..154S"><span id="translatedtitle">The formation of volcanic centers at the Colorado Plateau as a result of the passage of aqueous fluid through the oceanic lithosphere and the subcontinental mantle: New implications for the planetary water cycle in the western United States</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sommer, Holger; Regenauer-Lieb, Klaus; Gasharova, Biliana; Jung, Haemyeong</p> <p>2012-10-01</p> <p>We provide new petrological evidence for the strong influence of water on the formation of the oceanic lithospheric mantle, the subcontinental mantle above, and the continental lithosphere. Our analysis throws new light on the hypothesis that new continental lithosphere was formed by the passage of silicate-rich aqueous fluid through the sub-continental mantle. In order to investigate this hypothesis, we analyzed a representative collection of <span class="hlt">lherzolite</span> and harzburgite xenoliths from the sample volcano known as "The Thumb", located in the center of the Colorado Plateau, western United States. The studied sample collection exhibits multi-stage water enrichment processes along point, line and planar defect structures in nominally anhydrous minerals and the subsequent formation of the serpentine polymorph antigorite along grain boundaries and in totally embedded annealed cracks. Planar defect structures act like monomineralic and interphase grain boundaries in the oceanic lithosphere and the subcontinental mantle beneath the North American plate, which was hydrated by the ancient oceanic Farallon plate during the Cenozoic and Mesozoic eras. We used microspectroscopical, petrological, and seismological techniques to confirm multi-stage hydration from a depth of ˜150 km to just below the Moho depth. High-resolution mapping of the water distribution over homogeneous areas and fully embedded point, line and planar defects in olivine crystals of <span class="hlt">lherzolitic</span> and harzburgitic origin by synchrotron infrared microspectroscopy enabled us to resolve local wet spots and thus reconstruct the hydration process occurring at a depth of ˜150 km (T ≈ 1225 °C). These <span class="hlt">lherzolites</span> originated from the middle part of the Farallon mantle slab; they were released during the break up of the Farallon mantle slab, caused by the instability of the dipping slab. The background hydration levels in homogeneous olivines reached ˜138 ppm wt H2O, and the water concentration at the planar defects</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/20865000','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/20865000"><span id="translatedtitle">Water and its influence on the lithosphere-asthenosphere boundary.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Green, David H; Hibberson, William O; Kovács, István; Rosenthal, Anja</p> <p>2010-09-23</p> <p>The Earth has distinctive convective behaviour, described by the plate tectonics model, in which lateral motion of the oceanic lithosphere of basaltic crust and peridotitic uppermost mantle is decoupled from the underlying mechanically weaker upper mantle (asthenosphere). The reason for differentiation at the lithosphere-asthenosphere boundary is currently being debated with relevant observations from geophysics (including seismology) and geochemistry (including experimental petrology). Water is thought to have an important effect on mantle rheology, either by weakening the crystal structure of olivine and pyroxenes by dilute solid solution, or by causing low-temperature partial melting. Here we present a novel experimental approach to clarify the role of water in the uppermost mantle at pressures up to 6 GPa, equivalent to a depth of 190 km. We found that for <span class="hlt">lherzolite</span> in which a water-rich vapour is present, the temperature at which a silicate melt first appears (the vapour-saturated solidus) increases from a minimum of 970 °C at 1.5 GPa to 1,350 °C at 6 GPa. We have measured the water content in <span class="hlt">lherzolite</span> to be approximately 180 parts per million, retained in nominally anhydrous minerals at 2.5 and 4 GPa at temperatures above and below the vapour-saturated solidus. The hydrous mineral pargasite is the main water-storage site in the uppermost mantle, and the instability of pargasite at pressures greater than 3 GPa (equivalent to more than about 90 km depth) causes a sharp drop in both the water-storage capacity and the solidus temperature of fertile upper-mantle <span class="hlt">lherzolite</span>. The presence of interstitial melt in mantle with more than 180 parts per million of water at pressures greater than 3 GPa alters mantle rheology and defines the lithosphere-asthenosphere boundary. Modern asthenospheric mantle acting as the source for mid-oceanic ridge basalts has a water content of 50-200 parts per million (refs 3-5). We show that this matches the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015AGUFM.V53F3167G&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015AGUFM.V53F3167G&link_type=ABSTRACT"><span id="translatedtitle">Water in the lithospheric mantle beneath a Phanerozoic continental belt: FTIR analyses of Alligator Lake Xenoliths (Yukon, Canada)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gelber, M.; Peslier, A. H.; Brandon, A. D.</p> <p>2015-12-01</p> <p>Water in the mantle influences melting, metasomatism, viscosity and electrical conductivity. The Alligator Lake mantle xenolith suite is one of three bimodal peridotite suites from the northern Canadian Cordillera brought to the surface by alkali basalts, i.e., it consists of chemically distinct <span class="hlt">lherzolites</span> and harzburgites [1-2]. The <span class="hlt">lherzolites</span> have equilibration temperatures about 50 °C lower than the harzburgites and are thought to represent the fertile upper mantle of the region. The harzburgites might have come from slightly deeper in the mantle and/or be the result of a melting event above an asthenospheric upwelling detected as a seismic anomaly at 400-500 km depth [3]. Major and trace element data are best interpreted as the <span class="hlt">lherzolite</span> mantle having simultaneously experienced 20-25% partial melting and a metasomatic event to create the harzburgites [3]. Well-characterized xenoliths are being analyzed for water by FTIR. Harzburgites contain 29-52 ppm H2O in orthopyroxene (opx) and ~140 ppm H2O in clinopyroxene (cpx). The <span class="hlt">lherzolites</span> have H2O contents of 27-150 ppm in opx and 46-361 ppm in cpx. Despite correlating with enrichments in LREE, the water contents of the harzburgite pyroxenes are low relative to those of typical peridotite xenoliths [4], suggesting that the metasomatic agents were water-poor, contrarily to what has been suggested before [3]. The water content of cpx is about double that of opx indicating equilibrium. Olivine water contents are low (< 5 ppm H2O) and out of equilibrium with those of opx and cpx, which may be due to H loss during xenolith ascent. This is consistent with olivines containing more water in their cores than their rims. Olivines exclusively exhibit water bands in the 3400-3000 cm-1 range, which may be indicative of a reduced environment [5]. [1] Francis. 1987 JP 28, 569-97. [2] Eiche et al. 1987 CMP 95, 191-201. [3] Shi et al. 1997 CMP 131, 39-53. [4] Peslier et al. 2015 GGG 154, 98-117. [5] Bai et al. 1993 PCM 19, 460-71.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015Litho.212..189D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015Litho.212..189D"><span id="translatedtitle">Characterization of hydration in the mantle lithosphere: Peridotite xenoliths from the Ontong Java Plateau as an example</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Demouchy, Sylvie; Ishikawa, Akira; Tommasi, Andréa; Alard, Olivier; Keshav, Shantanu</p> <p>2015-01-01</p> <p>We report concentrations of hydrogen (H) in upper mantle minerals of peridotites (olivine and pyroxenes) transported by alnöitic lavas, which erupted on the southwestern border of the Ontong Java Plateau (Malaita, Solomon Islands, West Pacific). Unpolarized FTIR analyses show that olivine, orthopyroxene, and diopside contain 2-32 ppm, 162-362 ppm and 159-459 ppm wt H2O, respectively. In the studied <span class="hlt">lherzolites</span>, garnets are anhydrous. The concentration of hydrogen within individual olivine and pyroxene grains is almost homogeneous, indicating no evidence of dehydration or hydration by ionic diffusion. In the <span class="hlt">lherzolite</span>, the concentration of hydrogen in olivine tends to increase weakly with depth (based on geothermobarometry), consistent with the increase of water solubility with increasing water fugacity as a function of pressure, but concentrations remain well below water-saturation values determined experimentally. The highest concentration of H in olivine (32 ppm wt H2O) is, however, found in refractory spinel harzburgites, which equilibrated at depths of 85 km., while deeper specimens as the high-temperature spinel harzburgites, and some of the garnet <span class="hlt">lherzolites</span>, contain less hydrogen in olivine. Olivines from pyroxene- or pargasite-rich peridotites have also lower hydrogen concentrations. We interpret the high hydrogen concentrations in olivine from the refractory spinel harzburgites as due to (1) simultaneous hydration and metasomatism of the lithospheric mantle by a water-rich silicate melt/fluid, during which hydrogen follows MREE and where spinel harzburgite have experienced 'stealth' metasomatism, and/or (2) to a late 'fleeting' hydrogen metasomatism, which would hydrate the rock after this first 'stealth' metasomatism event. In the second case, the composition of the 'fleeting' percolating fluid (small volume fraction of very evolved fluids, with high volatiles concentration and transient properties) is likely to be linked to the decrease of the plume</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/569490','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/569490"><span id="translatedtitle">Platinum-group element abundance patterns in different mantle environments</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Rehkaemper, M.; Halliday, A.N.; Barfod, D.; Fitton, J.G.; Dawson, J.B.</p> <p>1997-11-28</p> <p>Mantle-derived xenoliths from the Cameroon Line and northern Tanzania display differences in their platinum-group element (PGE) abundance patterns. The Cameroon Line <span class="hlt">lherzolites</span> have uniform PGE patterns indicating a homogeneous upper mantle over several hundreds of kilometers, with approximately chondritic PGE ratios. The PGE patterns of the Tanzanian peridotites are similar to the PGE systematics of ultramafic rocks from ophiolites. The differences can be explained if the northern Tanzanian lithosphere developed in a fluid-rich suprasubduction zone environment, whereas the Cameroon Line lithosphere only experienced melt extraction from anhydrous periodotites. 32 refs., 2 figs., 1 tab.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70010076','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70010076"><span id="translatedtitle">Al-augite and Cr-diopside ultramafic xenoliths in basaltic rocks from western United States</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Wilshire, H.G.; Shervais, J.W.</p> <p>1975-01-01</p> <p>Ultramafic xenoliths in basalts from the western United States are divided into Al-augite and Cr-diopside groups. The Al-augite group is characterized by Al, Ti-rich augites, comparatively Fe-rich olivine and orthopyroxene, and Al-rich spinel, the Cr-diopside group by Cr-rich clinopyroxene and spinel and by Mg-rich olivine and pyroxenes. Both groups have a wide range of subtypes, but the Al-augite group is dominated by augite-rich varieties, and the Cr-diopside group by olivine-rich <span class="hlt">lherzolites</span>. ?? 1975.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012AGUFMOS51B1875C&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012AGUFMOS51B1875C&link_type=ABSTRACT"><span id="translatedtitle">Implications of spinel compositions for the petrotectonic history of abyssal peridotite from Southwest Indian Ridge (SWIR)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, T.; Jin, Z.; Wang, Y.; Tao, C.</p> <p>2012-12-01</p> <p>Abyssal peridotites generate at mid-ocean ridges. <span class="hlt">Lherzolite</span> and harzburgite are the main rock types of peridotites in the uppermost mantle. The <span class="hlt">lherzolite</span> subtype, less depleted and less common in ophiolites, characterizes mantle diapirs and slow-spreading ridges. Along the Earth's mid-ocean ridges, abyssal peridotites undergo hydration reactions to become serpentinite minerals, especially in slow to ultraslow spreading mid-ocean ridges. Spinel is common in small quantities in peridotites, and its compositions have often been used as petrogenetic indicators [1]. The Southwest Indian Ridge (SWIR) is one of the two ultraslow spreading ridges in the world. The studied serpentinized peridotite sample was collected by the 21st Voyage of the Chinese oceanic research ship Dayang Yihao (aka Ocean No. 1) from a hydrothermal field (63.5°E, 28.0°S, and 3660 m deep) in SWIR. The studied spinels in serpentinized <span class="hlt">lherzolite</span> have four zones with different compositions: relic, unaltered core is magmatic Al-spinels; micro- to nano- sized ferrichromite zoned particles; narrow and discontinuous magnetite rim; and chlorite aureoles. The values Cr# of the primary Al-spinels indicate the range of melting for abyssal peridotites from SWIR extends from ~4% to ~7% [2]. The alteration rims of ferrichromite have a chemical composition characterized by Fe enrichment and Cr# increase indicating chromite altered under greenschist-amphibolite facies. Magnetites formed in syn- and post- serpentinization. Chlorite (clinochlore) formed at the boundary and crack of spinel indicating it had undergone with low-temperature MgO- and SiO2-rich hydrothermal fluids [3]. It suggests that serpentinized <span class="hlt">lherzolite</span> from SWIR had undergone poly-stage hydration reactions with a wide range of temperature. Acknowledgments: EMPA experiment was carried out by Xihao Zhu and Shu Zheng in The Second Institute of Oceanography and China University of Geosciences, respectively. The work was supported by NSFC</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015Litho.224...32H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015Litho.224...32H"><span id="translatedtitle">Re-Os isotopic constraints on the evolution of the Bangong-Nujiang Tethyan oceanic mantle, Central Tibet</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Huang, Qi-Shuai; Shi, Ren-Deng; O'Reilly, Suzanne Y.; Griffin, William L.; Zhang, Ming; Liu, De-Liang; Zhang, Xiao-Ran</p> <p>2015-05-01</p> <p>Geochemical (including Re-Os isotopic) studies of the mantle rocks of ophiolites in the Bangong-Nujiang suture zone in central Tibet have provided a coherent picture of the evolution of the Bangong-Nujiang Tethyan oceanic mantle from mid-ocean ridge (MOR) to subduction-zone (SSZ) settings. Clinopyroxene (cpx)-harzburgites and <span class="hlt">lherzolites</span> in the Bangong Lake ophiolite were formed in a MOR setting, as demonstrated by the Cr# of spinels (< 0.60) and whole-rock LREE-depleted patterns. Suprachondritic 187Re/188Os ratios (up to 1.833) of cpx-harzburgites and their spinels can be explained by interaction with melts derived from high Re/Os sources. Re-depletion (TRD) model ages (0.48-0.55 Ga) suggest these rocks may represent a Pan-African domain beneath the Gondwana continent. High TiO2 contents of spinels and whole-rock samples imply that the <span class="hlt">lherzolites</span> were formed through a refertilization process. Similarly, Re-Os isotopic systematics of sulfides in the <span class="hlt">lherzolites</span> (187Re/188Os: 0.173-1.717, 187Os/188Os: 0.12646-0.17340) demonstrate that they are mixtures of primary and secondary sulfides. 187Os/188Os ratios (0.1211-0.1226) of whole-rock <span class="hlt">lherzolites</span> give TRD ages of 0.73-0.97 Ga, indicating the presence of Neoproterozoic lithospheric mantle under the spreading ridges. Mantle rocks in the SSZ-type ophiolites from Bangong Lake, Dongqiao and Nagqu reflect the complex evolution of the Bangong-Nujiang oceanic mantle during the SSZ stage. Most harzburgites from the Bangong Lake ophiolite give TRD ages of 1.0-1.5 Ga, possibly representing relics of a Mesoproterozoic lithospheric mantle. However, three samples have both high Os contents (1.32-4.45 ppb) and near-chondritic 187Os/188Os (0.1260-0.1297), and may represent Mesozoic oceanic lithospheric mantle. 187Os/188Os ratios of dunites and harzburgites from the Dongqiao and Nagqu ophiolites vary from 0.1174 to 0.1316 and give TRD ages up to 1.43 Ga, also suggesting the existence of a Mesoproterozoic lithospheric mantle which</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016JAESc.126....1Z&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016JAESc.126....1Z&link_type=ABSTRACT"><span id="translatedtitle">Variable mineralization processes during the formation of the Permian Hulu Ni-Cu sulfide deposit, Xinjiang, Northwestern China</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhao, Yun; Xue, Chunji; Zhao, Xiaobo; Yang, Yongqiang; Ke, Junjun; Zu, Bo</p> <p>2016-08-01</p> <p>The Permian Hulu Ni-Cu sulfide deposit is located at the southern margin of the Central Asian Orogenic Belt (CAOB) in Northern Xinjiang, Northwestern China. The host intrusion of the Hulu deposit is composed of a layered mafic-ultramafic sequence and a dike-like unit. The layered sequence is composed of harzburgite, <span class="hlt">lherzolite</span>, pyroxenite, gabbro, gabbrodiorite and diorite. The dike-like body comprises <span class="hlt">lherzolite</span> and gabbro. Sulfide orebodies occur mainly within the harzburgite, pyroxenite and <span class="hlt">lherzolite</span> at the base of the layered sequence and within the <span class="hlt">lherzolite</span> in the dike-like body. Sulfide mineralization from the Hulu deposit shows significant depletion of PGE relative to Cu and Ni. These elements show good positive correlations with S in the sulfide mineralization from the dike-like unit but relatively weak correlations in the sulfide mineralization from the layered sequence. The sulfide mineralization from the layered unit shows excellent positive correlations between Ir and Os, Ru or Rh, and poor relationships between Ir and Pt or Pd. On the contrary, sulfide mineralization from the dike-like unit shows good correlations in the diagrams of Os, Ru, Rh, Pt and Pd against Ir. Both high Cu/Pd ratios (8855-481,398) and our modeling indicate that PGE depletion resulted from sulfide removal in a deep staging magma chamber. The evolved PGE-depleted magmas then ascended to the shallower magma chamber and became sulfide saturation due to crustal contamination. Both low Se/S ratios (33.5 × 10-6-487.5 × 10-6) and a negative correlation between Se/S and Cu/Pd ratios are consistent with the addition of crustal S. A large number of sulfide liquids segregated with minor crystallization of monosulfide solid solution (MSS) in the shallower magma chamber. When new magma pulses with unfractionated sulfide droplets entered the shallower magma chamber, the sulfide slurry containing crystallized MSS may be disrupted and mixed with the unfractionated sulfide droplets. The</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFMMR33A1660S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFMMR33A1660S"><span id="translatedtitle">Fabric Characterization of Mantle beneath South Central North America: Constraints from Peridotite Xenoliths from Knippa and Kilbourne Hole</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Satsukawa, T.; Michibayashi, K.; Raye, U.; Stern, R. J.; Anthony, E. Y.</p> <p>2009-12-01</p> <p>Knippa quarry and Kilbourne Hole are sites where we can study samples of the upper mantle beneath Texas and New Mexico. Knippa peridotite xenoliths are hosted by ~86 Ma nepehlinites of the Balcones Igneous Province in central Texas. Kilbourne Hole maar, Potrillo volcanic field (PVF) near El Paso, erupted basanite approximately 10 Ka ago and thus the xenoliths represent present-day thermal and compositional character of this segment of the continental mantle. Both provide rare snapshots of upper mantle processes and compositions beneath south-central Laurentia. The xenolith suites are dominated by <span class="hlt">lherzolite</span>, harzburgite and dunite, although pyroxenites are also common at Kilbourne Hole. Temperatures determined using the Ca in opx thermometer (Brey and Kohler, 1990) range between 900 and 1000C. Kilbourne Hole peridotites are several types. Fine-grained <span class="hlt">lherzolite</span> has the lowest temperatures, porphyroclastic <span class="hlt">lherzolite</span> intermediate temperature, and harzburgite and dunite the highest temperature. Large olivine grains commonly contain subgrain boundaries. The dominant slip system in olivine was determined from the orientations of the axes of subgrain rotation and CPO data. Olivine CPO data show strong concentration in [100] and [100]{0kl} patterns in Knippa peridotites, and [100](010) and [010]-fiber patterns in Kilbourne peridotites. We interpret the development of [010]-fiber patterns to: (i) axial shortening or 3D transpressive deformation, (ii) activation of multiple glide directions, (iii) deformation in the presence of melt. Presence of melt is also indicated by xenolith elemental compositions, which indicate melt infiltration and reaction. CPO strength is characterized by the dimensionless texture index “J”. J-index of Knippa peridotites varies from 4.6 to 11.4. Kilbourne Hole peridotite J-indices positively correlate with temperature, varying from 5 to 10 for the low temperature <span class="hlt">lherzolite</span> to an unusually high value of 20 for the harzburgite and dunite</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70168926','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70168926"><span id="translatedtitle">Asthenosphere–lithosphere interactions in Western Saudi Arabia: Inferences from 3He/4He in xenoliths and lava flows from Harrat Hutaymah</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Konrad, Kevin;; Graham, David W; Thornber, Carl; Duncan, Robert A; Kent, Adam J.R.; Al-Amri, Abdulla</p> <p>2016-01-01</p> <p>Elevated 3He/4He in the western harrats has been observed only at Rahat (up to 11.8 RA; Murcia et al., 2013), a volcanic field situated above thinned lithosphere beneath the Makkah-Medinah-Nafud volcanic lineament. Previous work established that spinel <span class="hlt">lherzolites</span> at Hutaymah are sourced near the lithosphere-asthenosphere boundary (LAB), while other xenolith types there are derived from shallower depths within the lithosphere itself (Thornber, 1992). Helium isotopes are consistent with melts originating near the LAB beneath many of the Arabian harrats, and any magma derived from the Afar mantle plume currently appears to be of minor importance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014Litho.202..267S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014Litho.202..267S"><span id="translatedtitle">Composition and structure of the lithospheric mantle beneath NE Iran: Constraints from mantle xenoliths</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Su, Ben-Xun; Chung, Sun-Lin; Zarrinkoub, Mohammad Hossein; Pang, Kwan-Nang; Chen, Ling; Ji, Wei-Qiang; Brewer, Aaron; Ying, Ji-Feng; Khatib, Mohammad Mahdi</p> <p>2014-08-01</p> <p>A detailed study on petrology and mineral chemistry of 32 mantle xenoliths has been conducted to decipher the physical and chemical characteristics of the lithosphere beneath NE Iran. Spinel <span class="hlt">lherzolite</span>, the most abundant xenolith type, is made up of olivine, orthopyroxene, clinopyroxene, and spinel. Clinopyroxenes in the spinel <span class="hlt">lherzolites</span> display a primitive mantle-like composition, typical of non-cratonic peridotites. Pyroxenite, another major xenolith type, shows equilibrated textures and highly variable compositions including olivine websterite, websterite and clinopyroxenite. These pyroxenites, together with an equigranular dunite, delineate a clear metasomatic trend, characterized by systematic Mg#, Cr#, Al2O3, and TiO2 variations in the constituent minerals, coupled with light rare earth element enrichment and high field strength element depletion in clinopyroxene. The pyroxenites are therefore suggested to have formed by the interaction between garnet-bearing peridotites within the lithospheric mantle and melts from a stagnant slab within the asthenosphere. The lithospheric mantle may have undergone multiple stages of partial melting. The earliest stage, evidenced by the equigranular dunite, resulted in significant NiO depletion in olivine, low Al2O3 and TiO2 coupled with high Mg# and Cr# in clinopyroxene, and high Cr# in spinel. The second stage occurred more widely and gave rise to the large ion lithophile element depletion in clinopyroxenes of all rock types. The extent of melting is lower in the spinel <span class="hlt">lherzolites</span> than that in the pyroxenites, implying that the partial melting was not caused by decompression and thus most likely related to Tethyan subduction. A third and more recent melting stage, responsible for the spongy texture in some clinopyroxenes, is attributed to the extensional tectonic regime that started in the middle Miocene in the region. Temperature estimates show that both the spinel <span class="hlt">lherzolites</span> and pyroxenites equilibrated at ~ 900</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..1414193T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..1414193T"><span id="translatedtitle">Peridotite xenoliths from the Chersky belt (Yakutia): Infiltrated carbonate-rich melts leaving no metasomatic record</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tschegg, C.; Ntaflos, Th.</p> <p>2012-04-01</p> <p>The Chersky seismic belt (NE-Russia) forms the modern plate boundary of the Eurasian-North American continental plate. The geodynamic evolution of this continent-continent setting is highly complex and it remains a matter of debate, how the extent of the Mid-Arctic Ocean spreading influenced the North Asian continent in this region since the Eocene. We constrained a model (Tschegg et al. 2011, Lithos) showing that volcanism in the Chersky area was triggered by extension and thinning of the lithosphere combined with adiabatic upwelling of the underlying mantle at 37 Ma. This implicates that the rift tectonics of the Mid-Arctic Ocean, at that time, affected the North Asian continent causing volcanic activity. Luckily, the basanites that were studied for these purposes host a representative number of peridotite xenoliths, which allow further constraints on the evolution of this area. The suite of spinel peridotites (<span class="hlt">lherzolites</span> and harzburgites), pyroxenites and mega-crysts enable to characterize upper mantle conditions as well as to observe different processes within the lithospheric mantle beneath the Chersky belt. Equilibration temperatures of the spinel <span class="hlt">lherzolites</span> reveal approx. 900-1000 °C at pressures of 1-2 GPa, with melt extraction volumes around 4 %. The analyzed spinel harzburgites reflect equilibration at lower P-T conditions and around 8 % higher melt extraction rates. We were able to find a completely preserved interstitial melt droplet in a <span class="hlt">lherzolite</span>, in which a primary dolomite is in perfect phase contact with Na-rich alumosilicate glass and sodalite. Based on detailed and integrated investigations, we reconstructed origin and evolution of this spectacular carbonatic liquid that at depth differentiated from a carbonated silicate melt to an immiscible carbonate and silicate liquid, entered the <span class="hlt">lherzolite</span> and quenched shortly before it was transported in the xenolith to the earth surface. To our surprise, the carbonate-rich melt infiltration did not</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JAESc..79..312A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JAESc..79..312A"><span id="translatedtitle">Mineral chemistry and petrology of highly magnesian ultramafic cumulates from the Sarve-Abad (Sawlava) ophiolites (Kurdistan, NW Iran): New evidence for boninitic magmatism in intra-oceanic fore-arc setting in the Neo-Tethys between Arabia and Iran</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Allahyari, Khalil; Saccani, Emilio; Rahimzadeh, Bahman; Zeda, Ottavia</p> <p>2014-01-01</p> <p>The Sarve-Abad (Sawlava) ophiolitic complex consists of several tectonically dismembered ophiolitic sequences. They are located along the Main Zagros Thrust Zone, which marks the ophiolitic suture between the Arabian and Sanandaj-Sirjan continental blocks. They represent a portion of the southern Neo-Tethyan oceanic lithosphere, which originally existed between the Arabian (to the south) and Eurasian (to the north) continental margins. The Sarve-Abad ophiolites include cumulitic <span class="hlt">lherzolites</span> bearing minor dunite and chromitite lenses in places. The main rock-forming minerals in ultramafic cumulates are cumulus olivine and inter-cumulus clinopyroxene and orthopyroxene. Minor (<5%) chromian spinel occurs as both cumulus and inter-cumulus phases.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19770051908&hterms=Spinel&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DSpinel','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19770051908&hterms=Spinel&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DSpinel"><span id="translatedtitle">Pyroxene-spinel intergrowths in lunar and terrestrial pyroxenes</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Okamura, F. P.; Mccallum, I. S.; Stroh, J. M.; Ghose, S.</p> <p>1976-01-01</p> <p>The paper describes the oriented intergrowth of spinel and pyroxene in a pigeonite from Luna 20, an augite from Apollo 16 anorthosite 67075, and an orthopyroxene from a spinel <span class="hlt">lherzolite</span> nodule from the San Quintin volcanic field, Mexico. Using Mo K alpha radiation, photographs were taken of small, hand-picked single-crystals. A mechanism of exsolution is suggested in which the oxygen framework remains intact and spinel nuclei are formed by the migration of cations from interstitial sites and tetrahedral sites in the original non-stoichiometric pyroxene.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014RMxAC..44..133V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014RMxAC..44..133V"><span id="translatedtitle">The SNC Meteorites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Varela, M. E.</p> <p>2014-10-01</p> <p>The SNC (Shergotty-Nakhla-Chassigny) group, are achondritic meteorites. Of all SNC meteorites recognized up to date, <span class="hlt">shergottites</span> are the most abundant group. The petrographic study of Shergotty began several years ago when Tschermak, (1872) identified this rock as an extraterrestrial basalt. Oxygen isotopes in SNC meteorites indicate that these rocks are from a single planetary body (Clayton and Mayeda, 1983). Because the abundance patterns of rare gases trapped in glasses from shock melts (e.g., Pepin, 1985) turned out to be very similar to the Martian atmosphere (as analyzed by the Viking landers, Owen, 1976), the SNC meteorites are believed to originate from Mars (e.g. McSween, 1994). Possibly, they were ejected from the Martian surface either in a giant impact or in several impact events (Meyer 2006). Although there is a broad consensus for nakhlites and chassignites being -1.3Ga old, the age of the <span class="hlt">shergottites</span> is a matter of ongoing debates. Different lines of evidences indicate that these rocks are young (180Ma and 330-475Ma), or very old (> 4Ga). However, the young age in <span class="hlt">shergottites</span> could be the result of a resetting of these chronometers by either strong impacts or fluid percolation on these rocks (Bouvier et al., 2005-2009). Thus, it is important to check the presence of secondary processes, such as re-equilibration or pressure-induce metamorphism (El Goresy et al., 2013) that can produce major changes in compositions and obscure the primary information. A useful tool, that is used to reconstruct the condition prevailing during the formation of early phases or the secondary processes to which the rock was exposed, is the study of glass-bearing inclusions hosted by different mineral phases. I will discuss the identification of extreme compositional variations in many of these inclusions (Varela et al. 2007-2013) that constrain the assumption that these objects are the result of closed-system crystallization. The question then arises whether these</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.P54B..02A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.P54B..02A"><span id="translatedtitle">Northwest Africa 8159: New Type of Martian Meteorite</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Agee, C. B.; Muttik, N.; Ziegler, K. G.; Walton, E. L.; Herd, C. D. K.; McCubbin, F. M.; Santos, A. R.; Simon, J. I.</p> <p>2014-12-01</p> <p>Up until recently the orthopyroxenite ALH 84001 and basaltic breccia NWA 7034 were the only martian meteorites that did not fit within the common SNC types. However with the discovery of Northwest Africa (NWA) 8159, the diversity is expanded further with a third unique non-SNC meteorite type. The existence of meteorite types beyond the narrow range seen in SNCs is what might be expected from a random cratering sampling of a volcanically long-lived and geologically complex planet such as Mars. NWA 8159, a fine-grained, augite basalt, is a new type of martian meteorite, with SNC-like oxygen isotopes and Fe/Mn values, but having several characteristics that make it distinct from other known martian meteorite types. NWA 8159 is the only martian basalt type known to have augite as the sole pyroxene phase in its mineralogy. NWA 8159 is unique among martian meteorites in that it possesses both crystalline plagioclase and shock amorphized plagioclase, often observed within a single grain, the bracketing of plagioclase amorphization places the estimated peak shock pressures at >15 GPa and <23 GPa. Magnetite in NWA 8159 is exceptionally pure, whereas most martian meteorites contain solid-solution titano-magnetites, and this pure magnetite is a manifestation of the highest oxygen fugacity (fO2) yet observed in a martian meteorite. Although NWA 8159 has the highest fO2 of martian meteorites, it has a pronounced light rare earth (LREE) depletion pattern similar to that of very low fO2 basaltic <span class="hlt">shergottites</span> such as QUE 94201. Thus NWA 8159 displays a striking exception to well documented correlation between fO2 and LREE patterns in SNC meteorites. Finally, NWA 8159 stands apart from other martian meteorites in that it has an an early Amazonian age that is not represented in the SNCs, ALH 84001, or the NWA 7034 pairing group. NWA 8159 appears to be from an eruptive flow or shallow intrusion that is petrologically distinct from <span class="hlt">shergottite</span> basalts, and its crystallization age</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013M%26PS...48..493L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013M%26PS...48..493L"><span id="translatedtitle">The Ksar Ghilane 002 shergottite—The 100th registered Martian meteorite fragment</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Llorca, Jordi; Roszjar, Julia; Cartwright, Julia A.; Bischoff, Addi; Ott, Ulrich; Pack, Andreas; Merchel, Silke; Rugel, Georg; Fimiani, Leticia; Ludwig, Peter; Casado, José V.; Allepuz, David</p> <p>2013-03-01</p> <p>We report on the discovery of a new <span class="hlt">shergottite</span> from Tunisia, Ksar Ghilane (KG) 002. This single stone, weighing 538 g, is a coarse-grained basaltic <span class="hlt">shergottite</span>, mainly composed of maskelynitized plagioclase (approximately 52 vol%) and pyroxene (approximately 37 vol%). It also contains Fe-rich olivine (approximately 4.5 vol%), large Ca-phosphates, including both merrillites and Cl-apatites (approximately 3.4 vol%), minor amounts of silica or SiO2-normative K-rich glass, pyrrhotite, Ti-magnetite, ilmenite, and accessory baddeleyite. The largest crystals of pyroxene and plagioclase reach sizes of approximately 4 to 5 mm. Pyroxenes (Fs26-96En5-50Wo2-41). They typically range from cores of about Fs29En41Wo30 to rims of about Fs68En14Wo17. Maskelynite is Ab41-49An39-58Or1-7 in composition, but some can be as anorthitic as An93. Olivine (Fa91-96) occurs mainly within symplectitic intergrowths, in paragenesis with ilmenite, or at neighboring areas of symplectites. KG 002 is heavily shocked (S5) as indicated by mosaic extinction of pyroxenes, maskelynitized plagioclase, the occurrence of localized shock melt glass pockets, and low radiogenic He concentration. Oxygen isotopes confirm that it is a normal member of the SNC suite. KG 002 is slightly depleted in LREE and shows a positive Eu anomaly, providing evidence for complex magma genesis and mantle processes on Mars. Noble gases with a composition thought to be characteristic for Martian interior is a dominant component. Measurements of 10Be, 26Al, and 53Mn and comparison with Monte Carlo calculations of production rates indicate that KG 002 has been exposed to cosmic rays most likely as a single meteoroid body of 35-65 cm radius. KG 002 strongly resembles Los Angeles and NWA 2800 basaltic <span class="hlt">shergottites</span> in element composition, petrography, and mineral chemistry, suggesting a possible launch-pairing. The similar CRE ages of KG 002 and Los Angeles may suggest an ejection event at approximately 3.0 Ma.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/16710568','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/16710568"><span id="translatedtitle">Garnets from the Camafuca-Camazambo kimberlite (Angola).</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Correia, Eugénio A; Laiginhas, Fernando A T P</p> <p>2006-06-01</p> <p>This work presents a geochemical study of a set of garnets, selected by their colors, from the Camafuca-Camazambo kimberlite, located on northeast Angola. Mantle-derived garnets were classified according to the scheme proposed by Grütter et al. (2004) and belong to the G1, G4, G9 and G10 groups. Both sub-calcic (G10) and Ca-saturated (G9) garnets, typical, respectively, of harzburgites and <span class="hlt">lherzolites</span>, were identified. The solubility limit of knorringite molecule in G10D garnets suggests they have crystallized at a minimum pressure of about 40 to 45 kbar (4-4.5 GPa). The occurrence of diamond stability field garnets (G10D) is a clear indicator of the potential of this kimberlite for diamond. The chemistry of the garnets suggests that the source for the kimberlite was a <span class="hlt">lherzolite</span> that has suffered a partial melting that formed basaltic magma, leaving a harzburgite as a residue. PMID:16710568</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009GGG....10.5X06M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009GGG....10.5X06M"><span id="translatedtitle">Peridotites from a ductile shear zone within back-arc lithospheric mantle, southern Mariana Trench: Results of a Shinkai 6500 dive</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Michibayashi, K.; Ohara, Y.; Stern, R. J.; Fryer, P.; Kimura, J.-I.; Tasaka, M.; Harigane, Y.; Ishii, T.</p> <p>2009-05-01</p> <p>Two N-S fault zones in the southern Mariana fore arc record at least 20 km of left-lateral displacement. We examined the eastward facing slope of one of the fault zones (the West Santa Rosa Bank fault) from 6469 to 5957 m water depth using the submersible Shinkai 6500 (YK06-12 Dive 973) as part of a cruise by the R/V Yokosuka in 2006. The dive recovered residual but still partly fertile <span class="hlt">lherzolite</span>, residual <span class="hlt">lherzolite</span>, and dunite; the samples show mylonitic, porphyroclastic, and coarse, moderately deformed secondary textures. Crystal-preferred orientations of olivine within the peridotites show a typical [100](010) pattern, with the fabric intensity decreasing from rocks with coarse secondary texture to mylonites. The sampled peridotites therefore represent a ductile shear zone within the lithospheric mantle of the overriding plate. Peridotites were probably exposed in association with a tear in the subducting slab, previously inferred from bathymetry and seismicity. Furthermore, although the dive site is located in the fore arc close to the Mariana Trench, spinel compositions within the sampled peridotites are comparable to those from the Mariana Trough back arc, suggesting that back-arc basin mantle is exposed along the West Santa Rosa Bank fault.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001JAESc..19..517Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001JAESc..19..517Z"><span id="translatedtitle">Melt/mantle interaction and melt evolution in the Sartohay high-Al chromite deposits of the Dalabute ophiolite (NW China)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhou, M.-F.; Robinson, P. T.; Malpas, J.; Aitchison, J.; Sun, M.; Bai, W.-J.; Hu, X.-F.; Yang, J.-S.</p> <p>2001-06-01</p> <p>The Sartohay block of the Dalabute ophiolite consists chiefly of mantle harzburgite and <span class="hlt">lherzolite</span> with minor dunite. These rocks host voluminous chromite deposits with lenticular or vein-like shapes. The podiform chromitites are associated with, and cross-cut by, numerous troctolite dykes. Chromite in the chromitites has Al 2O 3 (23-31 wt%), TiO 2 (0.29-0.44 wt%), and Cr 2O 3 contents (<45 wt%) with Cr#s [100Cr/(Cr+Al)] (<60), typical of high-Al chromite deposits. The host peridotites in Sartohay have been texturally and geochemically modified by magmas from which the high-Al chromitites and mafic dykes formed. Dunites commonly envelop the podiform chromite bodies and show transitional contacts with the peridotites. Some of the peridotites and chromitites contain plagioclase that crystallized from impregnated melts. The dunite locally grades into troctolite with increasing plagioclase contents. As a result of melt impregnation, peridotites and dunites show variable Ca and Al contents and LREE enrichment. The parental magma of the chromitites was likely tholeiitic in composition, derived from partial melting of the asthenospheric mantle in a rising diapir. The interaction between this magma and pre-existing lithospheric mantle, composed of depleted <span class="hlt">lherzolite</span>, would have formed a more silicic, tholeiitic magma from which high-Al chromitites crystallized. During this interaction, harzburgite and dunite were depleted in modal pyroxene and enriched in some incompatible elements (such as Al, Ca and LREE) due to melt impregnation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMDI31A2548T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMDI31A2548T"><span id="translatedtitle">Multi-Isotopic evidence from West Eifel Xenoliths</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Thiemens, M. M.; Sprung, P.</p> <p>2015-12-01</p> <p>Mantle Xenoliths from the West Eifel intraplate volcanic field of Germany provide insights into the nature and evolution of the regional continental lithospheric mantle. Previous isotope studies have suggested a primary Paleoproterozoic depletion age, a second partial melting event in the early Cambrian, and a Variscan metasomatic overprint. Textural and Sr-Nd isotopic observations further suggest two episodes of melt infiltration of early Cretaceous and Quaternary age. We have investigated anhydrous, vein-free <span class="hlt">lherzolites</span> from this region, focusing on the Dreiser Weiher and Meerfelder Maar localities. Hand separated spinel, olivine, ortho- and clinopryoxene, along with host and bulk rocks were dissolved and purified for Rb-Sr, Sm-Nd, and Lu-Hf analysis on the Cologne/Bonn Neptune MC-ICP-MS. We find an unexpected discontinuity between mineral separates and whole rocks. While the latter have significantly more radiogenic ɛNd and ɛHf, mineral separates imply close-to chondritic compositions. Our Lu-Hf data imply resetting of the Lu-Hf systematic after 200 Ma. Given the vein-free nature of the <span class="hlt">lherzolites</span>, this appears to date to the second youngest metasomatic episode. We suggest that markedly radiogenic Nd and Hf were introduced during the Quarternary metasomatic episode and most likely reside on grain boundaries.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016Litho.244..205S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016Litho.244..205S"><span id="translatedtitle">Gold in the mantle: The role of pyroxenites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Saunders, J. Edward; Pearson, Norman J.; O'Reilly, Suzanne Y.; Griffin, William L.</p> <p>2016-02-01</p> <p>Mantle pyroxenites are the crystallised products of mafic silicate melts, which are commonly invoked as metasomatic agents in the upper mantle. This study has analysed the trace elements of sulfides, with a specific focus on gold, hosted in a suite of mantle pyroxenite xenoliths from Qilin in the Cathaysia Block, southeast China. These are compared with sulfides hosted in peridotite xenoliths from the same locality to assess the difference in the abundances of Au, and a suite of siderophile and chalcophile elements between the sulfides hosted in mobile melts in the upper mantle and their host "wall" rocks. Both the peridotite- and pyroxenite-hosted sulfides show a wide spectrum of trace element contents. The pyroxenite-hosted sulfides typically have PGE and Au concentrations that are an order of magnitude or more below those measured in the peridotite-hosted sulfides (<span class="hlt">lherzolite</span>-hosted sulfides: total PGE = 95 ± 118 ppm, Au = 1.4 ± 2.6 ppm; pyroxenite-hosted sulfides: total PGE = 0.25 ± 0.70 ppm, Au = 0.14 ± 0.39 ppm). Furthermore, the Ir group PGE (Ir, Os and Ru) are present in lower concentrations than the Pd-group PGE (Pd, Pt and Rh). This may lead to a distinct signature if the melts from which these sulfides crystallise interact with <span class="hlt">lherzolitic</span> sulfides. The overall low abundances of these elements within the pyroxenites suggests that the parent melts are an inefficient medium for enriching any of these elements in the upper mantle.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015OGeo....7...16M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015OGeo....7...16M"><span id="translatedtitle">Geochemistry of the Madawara Igneous Complex, Bundelkhand Craton, Central India: Implications for PGE Metallogeny</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Manavalan, Satyanarayanan; Singh, Surya Prakash; Balaram, Vysetti; Niranjan, Mohanty</p> <p>2015-12-01</p> <p>The southern part of the Bundelkhand craton contains a series of a E-W trending mafic and ultramafic rocks, about 40 km in length and 2-4 km wide, that occur as intrusions within the Bundelkhand Gneissic Complex (BnGC). They are confined between the Madawara- Karitoran and Sonrai-Girar shear zones. Dunite, harzburgite, <span class="hlt">lherzolite</span> and websterite are the commonly occurring ultramafic rocks that have high MgO, Ni, Cr, PGE and low Al2O3, CaO, K2O, TiO2 and V contents, and shows peridotitic affinity. A distinct trend of crystallization from peridotite to komatiitic basalt has been inferred from geochemical plots, which also indicates the occurrence of at least two varieties among the ultramafic suite of the Madawara ultramafic complex, namely, Group I comprising dunite, spinel peridotite, harzburgite and <span class="hlt">lherzolite</span>, and Group II consisting of pyroxenite, websterite and olivine websterite. In several places, the rocks of Group II have an intrusive relationship with Group I, and are relatively enriched in total platinum group elements (PGE ~ 300 ppb). The discrimination diagrams suggest that the PGE are enriched in low sulphur-fugacity source magma at moderate to deeper depths by high degree of partial melting of the mantle.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016JAfES.116..105B&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016JAfES.116..105B&link_type=ABSTRACT"><span id="translatedtitle">Sapphirine and fluid inclusions in Tel Thanoun mantle xenoliths,Syria</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bilal, Ahmad</p> <p>2016-04-01</p> <p>Volcanoes along the Syrian rift, which extend a distance of about 1000 km, brought to the surface mantle xenoliths within erupted basalts, during multiples periods of volcanic activity. Xenoliths in early Cretaceous volcanoes originate in the garnet peridotite field of the subcontinental mantle, whereas those in recent Cenozoic volcanoes, the prime object of this study, are issued from shallower levels (spinel peridotite field). The recent discovery of sapphirine-bearing websterite in Tel Thanoun, a small volcanic diatreme inside the larger Quaternary volcanic field (Djebel Al Arab), allows us to estimate the P-T evolution and fluid-rock interaction at the volcanic source. Harzburgites and <span class="hlt">lherzolites</span> are equilibrated at a temperature of about 1000 °C at a depth of 35-40 km. Sapphirine appears to have formed during cooling, at depth at a temperature of about 900 °C, at a time where spinel exsolution occurred in harzburgite and <span class="hlt">lherzolite</span> pyroxenes. This occurred in the presence of a high-density pure CO2 fluid phase, still present in primary fluid inclusions. The highly-aluminous sapphirine-bearing protolith might be former garnet websterite (possibly uplifted during cretaceous magmatism), which resided and cooled in the spinel peridotite stability field, and was then dragged and brought to the surface by quaternary basalts.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..1616878T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..1616878T"><span id="translatedtitle">P-T Equilibrium Conditions of Xenoliths from the Udachnaya Kimberlite Pipe: Thermal Perturbations in the Lithospheric Mantle</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tychkov, Nikolay; Agashev, Alexey; Malygina, Elena; Pokhilenko, Nikolay</p> <p>2014-05-01</p> <p>Integrated study of 250 peridotite xenoliths from Udachnaya -East pipe show difference in mineral paragenesises and textural-structural peculiarities in the different level of cratonic lithosphere mantle (CLM). The compositions of minerals were determined using EPMA. Thermobarometric parameters (Brey, Kohller, 1990) were determined for all rocks occupying different fields on geothermal curve. The deepest layer (the pressure interval of 5.0-7.0 GPa) contains mostly pophyroclastic <span class="hlt">lherzolites</span>. Anyway, some rocks of this layer have an idiomorphic texture being also enriched in incompatible components. Higher in the CLM sequence, the interval (4.2-6.3 GPa) is composed of the most depleted rocks: megacristalline ultradepleted harzburgite-dunites and depleted granular harzburgite-dunites, as well as <span class="hlt">lherzolites</span> in a subordinate amount. They correspond strate to 35 mW/m2 and partly overlap the deeper layer in dapth. It is likely that rocks of this layer are in equilibrium and were not subject to significant secondary changes due to kimberlite magma intrusion. Thus, this interval of the CLM sequence reflects the true (relic) geotherm for the area of the Udachnaya kimberlite pipe. Moreover, it is obvious that this interval was a major supplier of diamonds into kimberlites of the Udachnaya pipe. The interval of 4.2-2.0 GPa in the CLM sequence is also composed of coarse depleted <span class="hlt">lherzolites</span> and harzburgites. Rocks of this interval are slightly more enriched than those of the underlying interval. This is confirmed by the distinct predominance of <span class="hlt">lherzolites</span> over harzburgite-dunites. The heat flow in this layer varies in the range of 38-45 mW/m2 and shows a general tendency to increase with decreasing depth. According to occurrence of nonequilibrium mineral assemblages and increased heat flow relative to the major heat flow of 35 mW/m2, this interval is similar to the deepest interval of secondary enriched rocks. Interval of less than 2.0 GPa composed of spinel <span class="hlt">lherzolites</span> and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016Litho.240..295A&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016Litho.240..295A&link_type=ABSTRACT"><span id="translatedtitle">Petrological constraints on evolution of continental lithospheric mantle beneath the northwestern Ethiopian plateau: Insight from mantle xenoliths from the Gundeweyn area, East Gojam, Ethiopia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Alemayehu, Melesse; Zhang, Hong-Fu; Zhu, Bin; Fentie, Birhanu; Abraham, Samuel; Haji, Muhammed</p> <p>2016-01-01</p> <p>Detailed petrographical observations and in-situ major- and trace-element data for minerals from ten spinel peridotite xenoliths from a new locality in Gundeweyn area, East Gojam, have been examined in order to understand the composition, equilibrium temperature and pressure conditions as well as depletion and enrichment processes of continental lithospheric mantle beneath the Ethiopian plateau. The peridotite samples are very fresh and, with the exception of one spinel harzburgite, are all spinel <span class="hlt">lherzolites</span>. Texturally, the xenoliths can be divided into two groups as primary and secondary textures. Primary textures are protogranular and porphyroclastic while secondary ones include reaction, spongy and lamellae textures. The Fo content of olivine and Cr# of spinel ranges from 86.5 to 90.5 and 7.7 to 14.1 in the <span class="hlt">lherzolites</span>, respectively and are 89.8 and 49.8, respectively, in the harzburgite. All of the <span class="hlt">lherzolites</span> fall into the lower Cr# and Fo region in the olivine-spinel mantle array than the harzburgite, which indicates that they are fertile peridotites that experienced low degrees of partial melting and melt extraction. Orthopyroxene and clinopyroxene show variable Cr2O3 and Al2O3 contents regardless of their lithology. The Mg# of orthopyroxene and clinopyroxene are 87.3 to 90.1 and 85.8 to 90.5 for <span class="hlt">lherzolite</span> and 90.4 and 91.2 for harzburgite, respectively. The peridotites have been equilibrated at a temperature and pressure ranging from 850 to 1100 °C and 10.2 to 30 kbar, respectively, with the highest pressure record from the harzburgite. They record high mantle heat flow between 60 and 150 mW/m2, which is not typical for continental environments (40 mW/m2). Such a high geotherm in continental area shows the presence of active mantle upwelling beneath the Ethiopian plateau, which is consistent with the tectonic setting of nearby area of the Afar plume. Clinopyroxene of five <span class="hlt">lherzolites</span> and one harzburgite samples have a LREE enriched pattern and the rest</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015CoMP..170...13M&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015CoMP..170...13M&link_type=ABSTRACT"><span id="translatedtitle">Melting the hydrous, subarc mantle: the origin of primitive andesites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mitchell, Alexandra L.; Grove, Timothy L.</p> <p>2015-08-01</p> <p>This experimental study is the first comprehensive investigation of the melting behavior of an olivine + orthopyroxene ± spinel—bearing fertile mantle (FM) composition as a function of variable pressure and water content. The fertile composition was enriched with a metasomatic slab component of ≤0.5 % alkalis and investigated from 1135 to 1470 °C at 1.0-2.0 GPa. A depleted <span class="hlt">lherzolite</span> with 0.4 % alkali addition was also studied from 1225 to 1240 °C at 1.2 GPa. Melts of both compositions were water-undersaturated: fertile <span class="hlt">lherzolite</span> melts contained 0-6.4 wt% H2O, and depleted <span class="hlt">lherzolite</span> melts contained ~2.5 wt% H2O. H2O contents of experimental glasses are measured using electron microprobe, secondary ion mass spectrometry, and synchrotron-source reflection Fourier transform infrared spectroscopy, a novel technique for analyzing H2O in petrologic experiments. Using this new dataset in conjunction with results from previous hydrous experimental studies, a thermobarometer and a hygrometer-thermometer are presented to determine the conditions under which primitive lavas were last in equilibration with the mantle. These predictive models are functions of H2O content and pressure, respectively. A predictive melting model is also presented that calculates melt compositions in equilibrium with an olivine + orthopyroxene ± spinel residual assemblage (harzburgite). This model quantitatively predicts the following influences of H2O on mantle <span class="hlt">lherzolite</span> melting: (1) As melting pressure increases, melt compositions become more olivine-normative, (2) as melting extent increases, melt compositions become depleted in the normative plagioclase component, and (3) as melt H2O content increases, melts become more quartz-normative. Natural high-Mg# [molar Mg/(Mg + Fe2+)], high-MgO basaltic andesite and andesite lavas—or primitive andesites (PAs)—contain high SiO2 contents at mantle-equilibrated Mg#s. Their compositional characteristics cannot be readily explained by melting</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009EGUGA..11.7646E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009EGUGA..11.7646E"><span id="translatedtitle">Mineral chemistry and thermobarometry of peridotite xenoliths from Central Tien Shan basalts</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Egorova, V.; Batalev, V.; Simonov, V.; Bagdassarov, N.; Litasov, Yu.</p> <p>2009-04-01</p> <p>Meso-Cenozoic basaltoids were revealed in the Tien Shan on a vast area (>285.000 km2), from the mountainous framing of the Fergana basin in the west to the Dzhungar Alatau spurs in the east. They occur as dikes and stocks among the Paleozoic Tien Shan complexes. Basaltic flows and sills were found among the deposits of the Suluterek Formation localized in the basement of the section of continental sediments filling the Tien Shan neotectonic depressions. In the Toyun basin in China and in the Fergana valley, basaltic flows and sills occur among Cretaceous-Paleogene marine deposits. Meso-Cenozoic effusive bodies are mainly olivine and plagioclase basalts. The trace- and rare-earth-element compositions of rocks show that most of the studied basaltic series in the Tien Shan formed in within-plate magmatic systems related to mantle plume sources. Spinel <span class="hlt">lherzolite</span> xenoliths were found in basalts from Ortosuu sites located in Kyrgyzstan. New basalt sites with ultramafic xenoliths have high significance for reconstruction of the composition, structure and evolution of the upper mantle of Tien Shan and geodynamic processes in Central Asia. Spinel <span class="hlt">lherzolite</span> xenoliths are characterized by an anhydrous four-phase mineral assemblage: olivine, clinopyroxene, orthopyroxene, and brown Cr-spinel. Peridotite textures are largely protogranular. Rock forming minerals have high Mg# = 0.87-0.91 in Ol, 0.87-0.91 in Opx, 0.88-0.91 in Cpx, and 0.75-0.77 in Sp. NiO content in olivine reaches 0.4 wt.%. Clinopyroxenes are Cr-diopside and characterized by high Al2O3 (4.6-7.5 wt%), Cr2O3 (0.7 - 1.11 wt%), Na2O (1.4-1.7 wt%) contents and 0.44-0.5 Ca/(Ca+Mg) ratio. Cr/(Cr+Al) ratio in spinel is equal to 0.09-0.18. Temperatures of equilibration for spinel <span class="hlt">lherzolites</span> range from 920 to 1150C for Opx-Cpx thermometer and from 920 to 1070C for Ca-in-opx thermometer of Brey, Kohler (1990) and 912-1080C for Opx-Cpx thermometer of Wells (1977). Pressures calculated from Cpx barometer of Nimis (1999</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFM.T43C2037P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFM.T43C2037P"><span id="translatedtitle">Dynamics of Melting and Melt Migration as Inferred from Incompatible Trace Element Abundance in Abyssal Peridotites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Peng, Q.; Liang, Y.</p> <p>2008-12-01</p> <p>To better understand the melting processes beneath the mid-ocean ridge, we developed a simple model for trace element fractionation during concurrent melting and melt migration in an upwelling steady-state mantle column. Based on petrologic considerations, we divided the upwelling mantle into two regions: a double- lithology upper region where high permeability dunite channels are embedded in a <span class="hlt">lherzolite</span>/harzburgite matrix, and a single-lithology lower region that consists of partially molten <span class="hlt">lherzolite</span>. Melt generated in the single lithology region migrates upward through grain-scale diffuse porous flow, whereas melt in the <span class="hlt">lherzolite</span>/harzburgite matrix in the double-lithology region is allowed to flow both vertically through the overlying matrix and horizontally into its neighboring dunite channels. There are three key dynamic parameters in our model: degree of melting experienced by the single lithology column (Fd), degree of melting experienced by the double lithology column (F), and a dimensionless melt suction rate (R) that measures the accumulated rate of melt extraction from the matrix to the channel relative to the accumulated rate of matrix melting. In terms of trace element fractionation, upwelling and melting in the single lithology column is equivalent to non-modal batch melting (R = 0), whereas melting and melt migration in the double lithology region is equivalent to a nonlinear combination of non-modal batch and fractional melting (0 < R < 1). Given the nonlinear nature of the melting model and uncertainties in trace element data for the abyssal peridotite, we showed, with the help of Monte Carlo simulations, that it is difficult to invert for all three dynamic parameters from a set of incompatible trace element data with confidence. However, given Fd, it is quite possible to constrain F and R from incompatible trace element abundances in residual peridotite. As an illustrative example, we used the simple melting model developed in this study and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004AGUFM.V51B0552G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004AGUFM.V51B0552G"><span id="translatedtitle">Generation of Primary Kilauea Magmas: Constraints on Pressure, Temperature and Composition of Melts</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gudfinnsson, G. H.; Presnall, D. C.</p> <p>2004-12-01</p> <p>Picrite glasses from the submarine extension of Kilauea, Puna Ridge, which contain up to 15.0 wt% MgO, are the most magnesian glass samples reported from Hawaii. Their compositions form a distinct olivine fractionation trend. A comparison of this trend with phase relations of garnet <span class="hlt">lherzolite</span> in the CaO-MgO-Al2O3-SiO2 (CMAS) and CaO-MgO-Al2O3-SiO2-Na2O-FeO (CMASNF) system indicates that melts parental to the Hawaiian picrites are produced by melting of a garnet <span class="hlt">lherzolite</span> source at a pressure of 5 ± 1 GPa. The primary melt composition for Kilauea proposed by Clague et al. (1995), which has 18.4 wt% MgO, is close to the expected 5 GPa melt composition. By using the pressure-independent CMASNF geothermometer (Gudfinnsson and Presnall, 2001), we obtain a temperature of formation of 1450° C for the most magnesian Puna Ridge glass after correction for the presence of 0.4 wt% H2O and 0.7 wt% CO2. This assumes that the glass is not much modified after separation from the <span class="hlt">lherzolite</span> source. However, comparison with phase relations in the CMAS system strongly suggests that the most magnesian Puna Ridge glasses are the product of some olivine fractionation, and therefore give temperature considerably lower than that of the source. When applied to the proposed Kilauea primary melt composition of Clague et al. (1995), the CMASNF geothermometer gives a melting temperature of 1596° C or about 1565° C after correction for the presence of volatiles. This compares well with the anhydrous solidus temperature of 1600 ± 15° C at 5 GPa for the fertile KR4003 <span class="hlt">lherzolite</span> (Lesher et al., 2003), which has the complete garnet <span class="hlt">lherzolite</span> phase assemblage present at the solidus at this pressure. This consistency supports use of phase relations from the CMAS system and the CMASNF geothermometer to the Puna Ridge picrite compositions. With the pressure and temperature of melting known, one can calculate the potential temperature of the Hawaiian mantle, provided certain conditions are met</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19930022755&hterms=clay&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dclay','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19930022755&hterms=clay&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dclay"><span id="translatedtitle">Aqueous geochemistry on Mars: Possible clues from salts and clays in SNC meteorites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gooding, James L.</p> <p>1992-01-01</p> <p>All subgroups of the <span class="hlt">shergottite</span>, nakhlite, and chassignite (SNC) meteorites contain traces of water precipitated minerals that include various combinations of carbonates, sulfates, halides, ferric oxides, and aluminosilicate clays of preterrestrial origin. Oxygen three-isotope analysis of thermally extracted bulk water has confirmed that at least some of the water in SNC's is, indeed, extraterrestrial. A mixture of aqueous precipitates found in the SNC's, comprising smectite, illite, and gypsum (with minor halite +/- calcite and hematite), provides a self-consistent, though not unique, model for the bulk elemental composition of surface sediments at the Viking Lander sites. Therefore, if the salts and clays in SNC's are truly linked to aqueous alteration and soil formation on Mars, then the suite of SNC secondary minerals might provide the best currently available insight into near-surface martian chemistry.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20030110767&hterms=ALH84001&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DALH84001','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20030110767&hterms=ALH84001&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DALH84001"><span id="translatedtitle">Magnetite-Magnesioferrite Phase Relations and Application to ALH84001</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Koziol, Andrea M.</p> <p>2003-01-01</p> <p>Oxygen fugacity (fO2) is an important factor in planetary formation and evolution. Certain minerals or assemblages of minerals are stable only under certain fO2 conditions (at a constant T and P) and can be recorders of ambient fO2 during geologic processes. The best estimate of oxygen fugacity from mineral assemblages has implications, from large-scale models of planetary evolution to interpretation of single meteorites. For example, redox conditions are part of the discussion of the origin and history of <span class="hlt">shergottites</span>, basaltic rocks in meteorites from Mars [1-4]. In addition oxygen fugacity may be an important factor to consider in the interpretation of the carbonate and magnetite assemblages seen in ALH84001 [5].</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/11542002','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/11542002"><span id="translatedtitle">Fluid inclusions in stony meteorites--a cautionary note.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rudnick, R L; Ashwal, L D; Henry, D J; Gibson, E K; Roedder, E; Belkin, H E; Colucci, M T</p> <p>1985-02-15</p> <p>Newly discovered fluid inclusions in thin sections of Bjurbole chondrules, <span class="hlt">shergottite</span> EETA79001, lunar meteorite ALHA81005, and Apollo 16 glasses possess physical properties similar to those fluid inclusions found in thin sections of five stony meteorites recently described by Warner et al. (1983). The distribution and physical properties of these new fluid inclusions indicate they may be artifacts of thin section preparation; we suggest that saw coolant was sucked into vacuum vesicles in glasses and minerals through submicroscopic fractures produced during sawing. The similarities between these fluid inclusions and fluid inclusions previously described by Warner et al. (1983) lead us to conclude that many of the fluid inclusions reported earlier may be artifacts. Consequently, the origin of any fluid inclusions observed in thin sections of extraterrestrial materials must be interpreted with caution. The most probable true extraterrestrial fluid inclusions are those that have been observed in grains prepared without exposure to liquids of any kind. PMID:11542002</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20040085427&hterms=Barometers&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DBarometers','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20040085427&hterms=Barometers&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DBarometers"><span id="translatedtitle">Oxygen Fugacity of the Martian Mantle from Pigeonite/Melt Partitioning of Samarium, Europium and Gadolinium</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Musselwhite, S.; Jones, J. H.; Shearer, C.</p> <p>2004-01-01</p> <p>This study is part of an ongoing effort to calibrate the pyroxene/melt Eu oxybarometer for conditions relevant to the martian meteorites. There is fairly good agreement between a determinations using equilibria between Fe-Ti oxides and the estimates from Eu anomalies in <span class="hlt">shergottite</span> augites in tenns of which meteorites are more or less oxidized. The Eu calibration was for angrite composition pyroxenes which are rather extreme. However, application of a calibration for martian composition augites 113 does not significantly reduce the discrepancy between the two methods. One possible reason for this discrepancy is that augites are non-liquidus. The use of pigeonite rather than augite as the oxy-barometer phase is considered. We have conducted experiments on martian composition pigeonite/melt REE partitioning as a function of fO2.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19940016389&hterms=water&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DTitle%26N%3D0%26No%3D60%26Ntt%3Dwater','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19940016389&hterms=water&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DTitle%26N%3D0%26No%3D60%26Ntt%3Dwater"><span id="translatedtitle">High D/H ratios of water in magmatic amphiboles in Chassigny: Possible constraints on the isotopic composition of magmatic water on Mars</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Watson, L. L.; Hutcheon, I. D.; Epstein, S.; Stolper, E. M.</p> <p>1993-01-01</p> <p>The D/H ratios of kaersutitic amphiboles contained in magmatic inclusions in the <span class="hlt">Shergottites</span> Nakhlites Chassignites (SNC) meteorite Chassigny using the ion microprobe were measured. A lower limit on the delta(D(sub SMOW)) of the amphiboles is +1420 +/- 47 percent. Assuming Chassigny comes from Mars and the amphiboles have not been subject to alteration after their crystallization, this result implies either that recycling of D-enriched Martian atmosphere-derived waters into the planetary interior has taken place, or that the primordial hydrogen isotopic composition of the interior of Mars differs significantly from that of the Earth (delta(D(sub SMOW)) approximately 0 percent). In addition, the measurements indicate that the amphiboles contain less than 0.3 wt. percent water. This is much lower than published estimates, and indicates a less-hydrous Chassigny parent magma than previously suggested.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19820048233&hterms=Igneous+rocks&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3D%2528Igneous%2Brocks%2529','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19820048233&hterms=Igneous+rocks&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3D%2528Igneous%2Brocks%2529"><span id="translatedtitle">SNC meteorites - Igneous rocks from Mars</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wood, C. A.; Ashwal, L. D.</p> <p>1982-01-01</p> <p>It is argued that SNC (<span class="hlt">shergottite</span>, 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/17774694','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/17774694"><span id="translatedtitle">Water on Mars: Clues from Deuterium/Hydrogen and Water Contents of Hydrous Phases in SNC Meteorites.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Watson, L L; Hutcheon, I D; Epstein, S; Stolper, E M</p> <p>1994-07-01</p> <p>Ion microprobe studies of hydrous amphibole, biotite, and apatite in <span class="hlt">shergottite</span>-nakhlite-chassignite (SNC) meteorites, probable igneous rocks from Mars, indicate high deuterium/hydrogen (D/H) ratios relative to terrestrial values. The amphiboles contain roughly one-tentn as much water as expected, suggesting that SNC magmas were less hydrous than previously proposed. The high but variable D/H values of these minerals are best explained by postcrystallization D enrichment of initially D-poor phases by martian crustal fluids with near atmospheric D/H (about five times the terrestrial value). These igneous phases do not directly reflect the D/H ratios of martian "magmatic" water but provide evidence for a D-enriched martian crustal water reservoir. PMID:17774694</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19930050902&hterms=erosion+water&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Derosion%2Bwater','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19930050902&hterms=erosion+water&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Derosion%2Bwater"><span id="translatedtitle">Outgassed water on Mars - Constraints from melt inclusions in SNC meteorites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mcsween, Harry Y., Jr.; Harvey, Ralph P.</p> <p>1993-01-01</p> <p>The SNC (<span class="hlt">shergottite</span>-nakhlite-chassignite) meteorites, thought to be igneous rocks from Mars, contain melt inclusions trapped at depth in early-formed crystals. Determination of the pre-eruptive water contents of SNC parental magmas from calculations of the solidification histories of these amphibole-bearing inclusions indicates that Martian magmas commonly contained 1.4 percent water by weight. When combined with an estimate of the volume of igneous materials on Mars, this information suggests that the total amount of water outgassed since 3.9 billion years ago corresponds to global depths on the order of 200 meters. This value is significantly higher than previous geochemical estimates but lower than estimates based on erosion by floods. These results imply a wetter Mars interior than has been previously thought and support suggestions of significant outgassing before formation of a stable crust or heterogeneous accretion of a veneer of cometary matter.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1987Icar...70..153W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1987Icar...70..153W"><span id="translatedtitle">Mars regolith versus SNC meteorites - Possible evidence for abundant crustal carbonates</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Warren, P. H.</p> <p>1987-04-01</p> <p>Viking XRF analyses of the Martian regolith are compared with typical igneous rocks of the Earth, the Moon, the eucrite parent asteroid, and especially the <span class="hlt">shergottites</span>, nakhlites, and Chassigny (SNC) meteorites, which are suspected to be basalts and mafic cumulates from Mars. A striking feature of the Martian regolith is its extraordinarily low Ca/Si ratio. Several models might conceivably account for the low Ca/Si ratio, but the author suggests that most of the "missing" Ca was removed from the regolith as Ca-carbonate. Formation of a mass of carbonate equivalent to a global shell 20 m thick would suffice to remove 1000 mbar of CO2 from the Martian atmosphere. Thus, the peculiar Ca/Si ratio of the Martian regolith tends to support the hypothesis that the climate of Mars was once far warmer and wetter than it is today.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/1008887','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/1008887"><span id="translatedtitle">Oxidation state of vanadium in glass and olivine from terrestrial and Martian basalts: Implications for oxygen fugacity estimates</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Karner, J.M.; Sutton, S.R.; Papike, J.J.; Shearer, C.K.; Newville, M.</p> <p>2005-04-22</p> <p>Several studies have demonstrated the usefulness of synchrotron micro x-ray absorption near-edge structure ({mu}-XANES or SmX) spectroscopy in determining the oxidation state of elements in planetary materials. Delaney et al. used SmX to investigate the oxidation states of Fe, Cr, and V in extraterrestrial samples, and they later determined the oxidation state of V in experimental glasses as a function of oxygen fugacity. More recently, Sutton et al. studied the oxidation state of V in meteoritic fassaite and also in synthetic pyroxene. This report discusses our first results using SmX spectroscopy to determine the oxidation state of V in olivine and glass from a terrestrial ocean floor (OF) basalt and a martian basaltic <span class="hlt">shergottite</span> meteorite, Dar Al Gani 476. The goal of this and future studies is to use V (and Cr, Fe) valence states to determine the oxygen fugacity of basalts from different planetary bodies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20090006828','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20090006828"><span id="translatedtitle">Isotopic Evidence for a Martian Regolith Component in Martian Meteorites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rao, M. N.; Nyquist, L. E.; Bogard, D. D.; Garrison, D. H.; Sutton, S.</p> <p>2009-01-01</p> <p>Noble gas measurements in gas-rich impact-melt (GRIM) glasses in EET79001 <span class="hlt">shergottite</span> showed that their elemental and isotopic composition is similar to that of the Martian atmosphere [1-3]. The GRIM glasses contain large amounts of Martian atmospheric gases. Those measurements further suggested that the Kr isotopic composition of Martian atmosphere is approximately similar to that of solar Kr. The (80)Kr(sub n) - (80)Kr(sub M) mixing ratio in the Martian atmosphere reported here is approximately 3%. These neutron-capture reactions presumably occurred in the glass-precursor regolith materials containing Sm- and Br- bearing mineral phases near the EET79001/ Shergotty sites on Mars. The irradiated materials were mobilized into host rock voids either during shock-melting or possibly by earlier aeolian / fluvial activity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19830017366','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19830017366"><span id="translatedtitle">Mineralogy and chemistry of planets and meteorites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1983-01-01</p> <p>The data collection and the interpretation with respect to the mineralogy of meteoritic and terrestrial samples are summarized. The key conclusion is that the Moon underwent a series of melting episodes with complex crystal-liquid differentiation. It was not possible to determine whether the Moon melted completely or only partially. The stage is now set for a systematical geochemical and geophysical survey of the Moon. Emphasis was moved to meteorites in order to sort out their interrelationships from the viewpoint of mineral chemistry. Several parent bodies are needed for the achondrites with different chemical properties. Exploration of Mars is required to test ideas based on the possible assignment of <span class="hlt">shergottites</span>, nakhlites and chassignite to this planet. Early rocks on the Earth have properties consistent with a heavy bombardment and strong volcanic activity prior to 4 billion years ago.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1983JGR....88R.785N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1983JGR....88R.785N"><span id="translatedtitle">Do oblique impacts produce Martian meteorites?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nyquist, L. E.</p> <p></p> <p>Geochronological and geochemical characteristics of several achondritic meteorites match those expected of Martian rocks. Several authors have suggested that these meteorites might have originated on Mars, but no satisfactory explanation has been given of how they may have been ejected from the Martian surface. It is suggested that the oblique impact of large meteoroids may produce ejecta which is entrained with the ricocheting projectile and accelerated to velocities in excess of Martian escape velocity. This suggestion is based on earlier experimental studies of oblique impacts and on the observation of several large Martian craters with the characteristic 'butterfly' ejecta pattern produced by low angle impacts. Several acceleration mechanisms may act on the Martian ejecta. The considerations suggest that a Martian origin of the <span class="hlt">shergottite</span> meteorites is dynamically possible.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1983LPSC...13..785N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1983LPSC...13..785N"><span id="translatedtitle">Do oblique impacts produce Martian meteorites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nyquist, L. E.</p> <p>1983-11-01</p> <p>It is pointed out that several achondritic meteorites, classified as <span class="hlt">shergottites</span>, nakhlites, and chassignites, have a number of unusual characteristics. Following the suggestion of Wood and Ashwal (1981) these meteorites are collectively referred to as SNC meteorites. The major element compositions of the SNC meteorites are, in general, distinct from those of other meteorites and lunar samples, and similar to certain terrestrial rocks. The geochemical and geochronological characteristics of the SNC meteorites strongly imply that their parent body was on the order of lunar size or larger and geologically active. Serious attention must be given to the hypothesis of a Martian origin of the SNC meteorites and to dynamic processes capable of delivering Martian meteorites to earth. In connection with the present investigation, it is suggested that oblique impacts of large meteoroids can produce ejecta which is entrained with the ricocheting projectile and accelerated to velocities in excess of Martian escape velocity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19910017749','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19910017749"><span id="translatedtitle">Chemistry and mineralogy of Martian dust: An explorer's primer</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gooding, James L.</p> <p>1991-01-01</p> <p>A summary of chemical and mineralogical properties of Martian surface dust is offered for the benefit of engineers or mission planners who are designing hardware or strategies for Mars surface exploration. For technical details and specialized explanations, references should be made to literature cited. Four sources used for information about Martian dust composition: (1) Experiments performed on the Mars surface by the Viking Landers 1 and 2 and Earth-based lab experiments attempting to duplicate these results; (2) Infrared spectrophotometry remotely performed from Mars orbit, mostly by Mariner 9; (3) Visible and infrared spectrophotometry remotely performed from Earth; and (4) Lab studies of the <span class="hlt">shergottite</span> nakhlite chassignite (SNC) clan of meteorites, for which compelling evidence suggests origin on Mars. Source 1 is limited to fine grained sediments at the surface whereas 2 and 3 contain mixed information about surface dust (and associated rock) and atmospheric dust. Source 4 has provided surprisingly detailed information but investigations are still incomplete.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19920003711','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19920003711"><span id="translatedtitle">Iddingsite in the Nakhla meteorite: TEM study of mineralogy and texture of pre-terrestrial (Martian?) alterations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Treiman, Allan H.; Gooding, James L.</p> <p>1991-01-01</p> <p>Rusty-colored veinlets and patches in the Nakhla meteorite, identified as iddingsite, are pre-terrestrial. The rusty material is iddingsite (smectites + hematite + ferrihydrite); like terrestrial iddingsites, it probably formed during low-temperature interaction of olivine and water. Fragments of rusty material with host olivine were removed from thin sections of Nakhla with a tungsten needle. Fragments were embedded in epoxy, microtomed to 100 nanometers thickness, and mounted on Cu grids. Phase identifications were by Analytical Electron Microscopy/Energy Dispersive X-ray Analysis (EM/EDX) standardless chemical analyses (for silicates), electron diffraction (hematite and ferrihydrite), and lattice fringe imaging. This iddingsite in Nakhla is nearly identical to some formed on Earth, suggesting similar conditions of formation on the <span class="hlt">Shergottites</span>-Nakhlites-Chassigny (SNC) meteorite parent planet. A more detailed account of the results is presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19880051946&hterms=Calcium+Deposits&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DCalcium%2BDeposits','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19880051946&hterms=Calcium+Deposits&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DCalcium%2BDeposits"><span id="translatedtitle">Calcium carbonate and sulfate of possible extraterrestrial origin in the EETA 79001 meteorite</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gooding, James L.; Zolensky, Michael E.; Wentworth, Susan J.</p> <p>1988-01-01</p> <p>Two varieties of Ca-carbonate were found in a total of three interior (greater than 2-cm depth) samples of glass inclusions from the <span class="hlt">shergottite</span> meteorite, Elephant Moraine, Antarctica, A79001. Two of the samples, including the largest deposit around a vug near the center of the meteorite (8-cm depth), contained veins of granular calcite with significant Mg and P, either as Mg-calcite with dissolved P or as calcite with very finely intergrown Mg-bearing phosphate. The second variety, which occurred in a third sample with a previously documented high concentration of trapped gases, consisted of disseminated 10-20-micron anhedral grains of nearly pure CaCO3 and was intimately associated with laths and needles of Ca-sulfate (possibly gypsum). All evidence considered, it is probable that both varieties of Ca-carbonate (and the Ca-sulfate) formed on a planetary body (probably Mars) before the meteorite fell on earth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19920019778&hterms=Keynes&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DKeynes','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19920019778&hterms=Keynes&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DKeynes"><span id="translatedtitle">The stable isotopic compositions of indigenous carbon-bearing components in EETA 79001</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hartmetz, C. P.; Wright, I. P.; Pillinger, C. T.</p> <p>1992-01-01</p> <p>It is now widely accepted that the most likely source of SNC meteorites is Mars. An oblique impact on Mars, or vaporization of permafrost, by an impactor seem to be the most likely ejection mechanisms capable of accelerating material to the 5 km/s velocity needed to overcome the gravitational field of Mars. These ejection mechanisms involve a large shock event in the SNC class, the <span class="hlt">shergottites</span> EETA 79001 and ALHA 77055 are the most likely shocked samples, in which whole rock pressures of 35 to 45 GPa have been estimated. Martian weathering products have also been identified in EETA 79001. Here, the author started a series of analyses of EETA 79001 using a high-sensitivity static mass spectrometer capable of measuring sub-nanogram quantities of carbon. Recent measurements of lithology C confirm that the shock-implanted atmospheric CO2 is released during the 1100 to 1200 C step.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20040060020&hterms=Basalt&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DBasalt','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20040060020&hterms=Basalt&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DBasalt"><span id="translatedtitle">Sulfide Stability of Planetary Basalts</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Caiazza, C. M.; Righter, K.; Gibson, E. K., Jr.; Chesley, J. T.; Ruiz, J.</p> <p>2004-01-01</p> <p>The isotopic system, 187Re 187Os, can be used to determine the role of crust and mantle in magma genesis. In order to apply the system to natural samples, we must understand variations in Re/Os concentrations. It is thought that low [Os] and [Re] in basalts can be attributed to sulfide (FeS) saturation, as Re behaves incompatibly to high degrees of evolution until sulfide saturation occurs [1]. Previous work has shown that lunar basalts are sulfide under-saturated, and mid-ocean ridge, ocean-island and Martian (<span class="hlt">shergottites</span>) basalts are saturated [2,3]. However, little is known about arc basalts. In this study, basaltic rocks were analyzed across the Trans-Mexican Volcanic Belt.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016E%26PSL.433..241B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016E%26PSL.433..241B"><span id="translatedtitle">A Pb isotopic resolution to the Martian meteorite age paradox</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bellucci, J. J.; Nemchin, A. A.; Whitehouse, M. J.; Snape, J. F.; Kielman, R. B.; Bland, P. A.; Benedix, G. K.</p> <p>2016-01-01</p> <p>Determining the chronology and quantifying various geochemical reservoirs on planetary bodies is fundamental to understanding planetary accretion, differentiation, and global mass transfer. The Pb isotope compositions of individual minerals in the Martian meteorite Chassigny have been measured by Secondary Ion Mass Spectrometry (SIMS). These measurements indicate that Chassigny has mixed with a Martian reservoir that evolved with a long-term 238U/204Pb (μ) value ˜ two times higher than those inferred from studies of all other Martian meteorites except 4.428 Ga clasts in NWA7533. Any significant mixing between this and an unradiogenic reservoir produces ambiguous trends in Pb isotope variation diagrams. The trend defined by our new Chassigny data can be used to calculate a crystallization age for Chassigny of 4.526 ± 0.027 Ga (2σ) that is clearly in error as it conflicts with all other isotope systems, which yield a widely accepted age of 1.39 Ga. Similar, trends have also been observed in the <span class="hlt">Shergottites</span> and have been used to calculate a >4 Ga age or, alternatively, attributed to terrestrial contamination. Our new Chassigny data, however, argue that the radiogenic component is Martian, mixing occurred on the surface of Mars, and is therefore likely present in virtually every Martian meteorite. The presence of this radiogenic reservoir on Mars resolves the paradox between Pb isotope data and all other radiogenic isotope systems in Martian meteorites. Importantly, Chassigny and the <span class="hlt">Shergottites</span> are likely derived from the northern hemisphere of Mars, while NWA 7533 originated from the Southern hemisphere, implying that the U-rich reservoir, which most likely represents some form of crust, must be widespread. The significant age difference between SNC meteorites and NWA 7533 is also consistent with an absence of tectonic recycling throughout Martian history.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/23887429','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/23887429"><span id="translatedtitle">Solving the Martian meteorite age conundrum using micro-baddeleyite and launch-generated zircon.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Moser, D E; Chamberlain, K R; Tait, K T; Schmitt, A K; Darling, J R; Barker, I R; Hyde, B C</p> <p>2013-07-25</p> <p>Invaluable records of planetary dynamics and evolution can be recovered from the geochemical systematics of single meteorites. However, the interpreted ages of the ejected igneous crust of Mars differ by up to four billion years, a conundrum due in part to the difficulty of using geochemistry alone to distinguish between the ages of formation and the ages of the impact events that launched debris towards Earth. Here we solve the conundrum by combining in situ electron-beam nanostructural analyses and U-Pb (uranium-lead) isotopic measurements of the resistant micromineral baddeleyite (ZrO2) and host igneous minerals in the highly shock-metamorphosed <span class="hlt">shergottite</span> Northwest Africa 5298 (ref. 8), which is a basaltic Martian meteorite. We establish that the micro-baddeleyite grains pre-date the launch event because they are shocked, cogenetic with host igneous minerals, and preserve primary igneous growth zoning. The grains least affected by shock disturbance, and which are rich in radiogenic Pb, date the basalt crystallization near the Martian surface to 187 ± 33 million years before present. Primitive, non-radiogenic Pb isotope compositions of the host minerals, common to most <span class="hlt">shergottites</span>, do not help us to date the meteorite, instead indicating a magma source region that was fractionated more than four billion years ago to form a persistent reservoir so far unique to Mars. Local impact melting during ejection from Mars less than 22 ± 2 million years ago caused the growth of unshocked, launch-generated zircon and the partial disturbance of baddeleyite dates. We can thus confirm the presence of ancient, non-convecting mantle beneath young volcanic Mars, place an upper bound on the interplanetary travel time of the ejected Martian crust, and validate a new approach to the geochronology of the inner Solar System. PMID:23887429</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016GeCoA.187..279C&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016GeCoA.187..279C&link_type=ABSTRACT"><span id="translatedtitle">A new approach to cosmogenic corrections in 40Ar/39Ar chronometry: Implications for the ages of Martian meteorites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cassata, W. S.; Borg, L. E.</p> <p>2016-08-01</p> <p>Anomalously old 40Ar/39Ar ages are commonly obtained from <span class="hlt">Shergottites</span> and are generally attributed to uncertainties regarding the isotopic composition of the trapped component and/or the presence of excess 40Ar. Old ages can also be obtained if inaccurate corrections for cosmogenic 36Ar are applied. Current methods for making the cosmogenic correction require simplifying assumptions regarding the spatial homogeneity of target elements for cosmogenic production and the distribution of cosmogenic nuclides relative to trapped and reactor-derived Ar isotopes. To mitigate uncertainties arising from these assumptions, a new cosmogenic correction approach utilizing the exposure age determined on an un-irradiated aliquot and step-wise production rate estimates that account for spatial variations in Ca and K is described. Data obtained from NWA 4468 and an unofficial pairing of NWA 2975, which yield anomalously old ages when corrected for cosmogenic 36Ar using conventional techniques, are used to illustrate the efficacy of this new approach. For these samples, anomalous age determinations are rectified solely by the improved cosmogenic correction technique described herein. Ages of 188 ± 17 and 184 ± 17 Ma are obtained for NWA 4468 and NWA 2975, respectively, both of which are indistinguishable from ages obtained by other radioisotopic systems. For other <span class="hlt">Shergottites</span> that have multiple trapped components, have experienced diffusive loss of Ar, or contain excess Ar, more accurate cosmogenic corrections may aid in the interpretation of anomalous ages. The trapped 40Ar/36Ar ratios inferred from inverse isochron diagrams obtained from NWA 4468 and NWA 2975 are significantly lower than the Martian atmospheric value, and may represent upper mantle or crustal components.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150002918','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150002918"><span id="translatedtitle">The Mineralogical Record of Oxygen Fugacity Variation and Alteration in Northwest Africa 8159: Evidence for Interaction Between a Mantle Derived Martian Basalt and a Crustal Component(s)</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Shearer, Charles K.; Burger, Paul V.; Bell, Aaron S.; McCubbin, Francis M.; Agee, Carl; Simon, Justin I.; Papike, James J.</p> <p>2015-01-01</p> <p>A prominent geochemical feature of basaltic magmatism on Mars is the large range in initial Sr isotopic ratios (approx. 0.702 - 0.724) and initial epsilon-Nd values (approx. -10 to greater than +50). Within this range, the <span class="hlt">shergottites</span> fall into three discreet subgroups. These subgroups have distinct bulk rock REE patterns, mineral chemistries (i.e. phosphate REE patterns, Ni, Co, V in olivine), oxygen fugacity of crystallization, and stable isotopes, such as O. In contrast, nakhlites and chassignites have depleted epsilon-Nd values (greater than or equal to +15), have REE patterns that are light REE enriched, and appear to have crystallized near the FMQ buffer. The characteristics of these various martian basalts have been linked to different reservoirs in the martian crust and mantle, and their interactions during the petrogenesis of these magmas. These observations pose interesting interpretive challenges to our understanding of the conditions of the martian mantle (e.g. oxygen fugacity) and the interaction of mantle derived magmas with the martian crust and surface. Martian meteorite NWA 8159 is a unique fine-grained augite basalt derived from a highly depleted mantle source as reflected in its initial epsilon-Nd value, contains a pronounced light REE depleted pattern, and crystallized presumably under very oxidizing conditions. Although considerably older than both <span class="hlt">shergottites</span> and nahklites, it has been petrogenetically linked to both styles of martian magmatism. These unique characteristics of NWA 8159 may provide an additional perspective for deciphering the petrogenesis of martian basalts and the nature of the crust of Mars.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_23 --> <div id="page_24" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="461"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003EAEJA.....5124B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003EAEJA.....5124B"><span id="translatedtitle">Shock-Induced Melting of Martian Basalts: Insights on Subducting Oceanic Crust Melting Processes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Beck, P.; Gillet, P.; Barrat, J.-A.; Gautron, L.; Daniel, I.; El Goresy, A.</p> <p>2003-04-01</p> <p>Experiments carried out on rocks at upper and lower mantle P-T conditions have produced series of candidate minerals for the Earth mantle mineralogical model. Basaltic compositions can also suffer ultra high-pressure and temperature when subducting in the mantle. The phase diagram of basalts has been studied to characterize potential chemical and mineralogical heterogeneities produced by partial melting and phase transformations of the oceanic crust. <span class="hlt">Shergottites</span> that represent the most important sub-class of Martian meteorite have compositions close to terrestrial basalts and gabbros. During their extraction from Mars, they were severely shocked with pressures up to 50 GPa. These shocks induced partial melting. These melt pocket are an opportunity to study melting phenomena of basaltic compositions (i.e. oceanic crust) under high-pressure. We have performed a Raman spectroscopy investigation to determine the mineralogy of the melt pockets. Four <span class="hlt">shergottites</span> were studied, NWA 480, NWA 856, NWA 1068 and Zagami. In each meteorite, abundant "large" minerals in melt pockets are hollandite (both Ca-Na and K-Na hollandite), stishovite, amorphous pyroxene and high-pressure phosphate. Meltpocket matrix seems to have a similar mineralogy as "megacrysts". In NWA 856 we observed at a melt pocket rim that maskelynite successively transforms into hollandite, and a polycrystalline aggregate. This aggregate was identified as a mixture of stishovite and a calcium aluminosilicate phase (CAS), a phase previously described in high-pressure experiments, but never observed in natural samples. The Raman spectra identifies unambiguously this silicate of composition CaAl_4Si_2O11 and of Ba-ferrite type structure. Such a phase is supposed to be present in basalt subsolidus melting experiments for pressures above 25 GPa and temperatures between 2500 and 2700 K. Its discovery reinforces the proposition that this CAS phase is a valuable candidate for hosting Al in subducting oceanic crust.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993Metic..28..400M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993Metic..28..400M"><span id="translatedtitle">Cosmogenic Radionuclides in Antarctic Meteorites: Preliminary Results on Terrestrial Ages and Temporal Phenomena</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Michlovich, E.; Vogt, S.; Wolf, S. F.; Elmore, D.; Lipschutz, M. E.</p> <p>1993-07-01</p> <p> the production rates for these radionuclides in this group of meteorites to be 18.2 +/- 2.3 and 58 +/- 13 dpm/kg respectively, consistent with production rates cited for falls [8]. Cosmic ray exposure ages using the ^10Be/^21Ne method outlined by Graf et al. [9] substantially agree with ages calculated from noble gases alone. Similar agreements are obtained between cosmic ray exposure ages based solely on noble gases and those calculated using ^26Al/^21Ne [9]. We calculated terrestrial ages using the secular equilibrium distribution for ^36Cl of 22.8 +/- 3.1 dpm/kg [10]. Our results are similar to those seen by Nishiizumi et al. [10], with a few ages ranging up to several hundred thousand years. It is worth noting that the <span class="hlt">Yamato</span> meteorites measured in the present study, all of which happen to have been collected in the 1979 recovery effort ("Y79"), have a much older terrestrial age distribution (median age of 140 ka) than the <span class="hlt">Yamato</span> distribution shown in [10]. We find it interesting that our <span class="hlt">Yamato</span> age distribution is, however, consistent with the distribution of Y79 ages (median age, 110 ka) listed in [10], and that non-Y79 <span class="hlt">Yamato</span> meteorites (median age in [10], 22 ka) seem to be responsible for a disproportionate number of the youngest <span class="hlt">Yamato</span> meteorites. This possible collection area phenomenon is under investigation. Preliminary statistical analysis of the results using the preliminary terrestrial ages calculated here, trace-element data [3,4,11], and the methods elucidated in [2] is consistent with the notion that the meteorite flux sampled by the Earth has changed as a function of time. The latest results will be presented in Vail. References: [1] Koeberl C. and Cassidy W. A. (1991) GCA, 55, 3-18. [2] Lipschutz M. E. and Samuels S. M. (1991) GCA, 55, 19-34. [3] Wolf S. F. and Lipschutz M. E. (1992) LPS XXIII, 1545-1546. [4] Dodd R. T. et al. (1993) JGR, submitted. [5] Wetherill G. W. (1986) Nature, 319, 357-358. [6] Schultz L., personal communication. [7</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009EGUGA..1112146A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009EGUGA..1112146A"><span id="translatedtitle">Implications of an ultramafic body in a basalt-dominated oceanic hydrothermal system on the vent fluid composition and on processes within sediments overlying a hydrothermal discharge zone: results of reactive-transport modeling</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Alt-Epping, P.; Diamond, L. W.</p> <p>2009-04-01</p> <p>We use 2D reactive transport simulations to assess the hydraulic, thermal and chemical implications of an ultramafic body of <span class="hlt">lherzolitic</span> composition within a basalt-dominated oceanic hydrothermal system. The simulations are fully coupled and hence account for the progressive serpentinization and the associated porosity/permeability reduction of the model <span class="hlt">lherzolite</span> over time. We focus on the chemical fingerprints that reveal the presence of the ultramafic body at depth and that may be detected by direct seafloor exploration. These are the vent fluid composition and the porewater and mineral alteration within the rock column overlying a hydrothermal discharge zone. We compare ocean crust sections with and without sedimentary cover. Simulations suggest that the boundary between the basalt and the <span class="hlt">lherzolite</span> constitutes a sharp reaction front. The type and distribution of alteration phases that form at the reaction front are a result of fluid flow across the basalt-<span class="hlt">lherzolite</span> interface and thus are determined by the geometry and rate of hydrothermal fluid flow. Consequently, observations of the occurrence and extent of alteration phases, such as Fe-rich chlorite in the <span class="hlt">lherzolite</span> or of rodingitization of the basalt, may be interpreted in terms of the reactive-transport model to reconstruct paleo-fluid flow in the permeable oceanic basement. The alteration of the <span class="hlt">lherzolite</span> produces a fluid that is strongly reducing and depleted in silica. The most important chemical indicator of this rock-water interaction is an elevated H2 concentration. Under reducing (i.e. SO4-2 and CO2 free) conditions the enrichment in H2 is proportional to the extent of reaction between the fluid and the ultramafic rock. Under these conditions H2 behaves conservatively and the fluid remains enriched in H2 even though the concentration of all other major aqueous species is quickly buffered to new values when the fluid subsequently passes through basalt. This produces a vent fluid which is</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006GeCoA..70.5957D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006GeCoA..70.5957D"><span id="translatedtitle">Evolved mare basalt magmatism, high Mg/Fe feldspathic crust, chondritic impactors, and the petrogenesis of Antarctic lunar breccia meteorites Meteorite Hills 01210 and Pecora Escarpment 02007</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Day, James M. D.; Floss, Christine; Taylor, Lawrence A.; Anand, Mahesh; Patchen, Allan D.</p> <p>2006-12-01</p> <p>Antarctic lunar meteorites Meteorite Hills 01210 and Pecora Escarpment 02007 are breccias that come from different regolith lithologies on the Moon. MET 01210 is composed predominantly of fractionated low-Ti basaltic material and is classified as an immature, predominantly basaltic glassy matrix regolith breccia. PCA 02007 is a predominantly feldspathic regolith breccia consisting of metamorphosed feldspathic, noritic, troctolitic and noritic-anorthosite clasts, agglutinate and impact-glasses, as well as a number of basaltic clasts with mare and possible non-mare affinities. The basalt clasts in MET 01210 have undergone 'Fenner' trend enrichments in iron and may also have witnessed late-stage crystallization of zircon or a zirconium-rich mineral. Some of the features of MET 01210 are similar to other basaltic lunar breccia meteorites (e.g., Northwest Africa 773; Elephant Moraine 87521/96008; <span class="hlt">Yamato</span> 793274/981031), but it is not paired with them. The presence of metamorphic anorthositic clasts as well as agglutinates indicates a small regolith component. Similarities with previously discovered evolved (e.g., LaPaz Icefield 02205; Northwest Africa 032) and ferroan (e.g., Asuka 881757; <span class="hlt">Yamato</span> 793169) basaltic lunar meteorites suggest a similar mare source region for MET 01210. Despite lack of evidence for pairing, PCA 02007 shares many features with other feldspathic regolith breccias (e.g., <span class="hlt">Yamato</span> 791197, Queen Alexandra Range 94281), including a high Mg/Fe whole-rock composition, glass spherules, agglutinate fragments and a diverse clast inventory spanning the range of ferroan anorthosite and high magnesium suite rocks. Some of the basalt fragments in this sample are fractionated and have an igneous origin. However, the majority of the basalt fragments are impact melt clasts. PCA 02007 supports previous studies of feldspathic lunar meteorites that have suggested an aluminous crust for the Moon, with compositions more similar to magnesium granulite breccias than</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.T51A2562N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.T51A2562N"><span id="translatedtitle">Crustal architecture of the eastern margin of Japan Sea: back-arc basin opening and contraction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>No, T.; Sato, T.; Takahashi, N.; Kodaira, S.; Kaneda, Y.; Ishiyama, T.; Sato, H.</p> <p>2012-12-01</p> <p>Although large earthquakes such as the 1964 Niigata earthquake (M 7.5), 1983 Nihonkai-Chubu earthquake (M 7.8), and 1993 Hokkaido Nansei-Oki earthquake (M 7.8) have caused large amounts of damage to the eastern margin of the Japan Sea, a substantial number of seismic studies have been conducted for the seismogenic zone on the Pacific Ocean side of Japan. In addition, the detail of the source fault model for the eastern margin of the Japan Sea is not well defined for all cases. This highlights the need for further studies to investigate seismic imaging. Therefore, we have collaborated with other Japanese research institutions for a project titled "Priority Investigations of Strain Concentration Areas" (which is funded by Special Coordination Funds for Promoting Science and Technology, Japan). This project has conducted seismic surveys from 2009 to 2012 using the deep-sea research vessel, Kairei, from the Japan Agency for Marine-Earth Science and Technology. There is a strain concentration area in the eastern part of the survey area (Okamura et al., 1995). The western part of the survey area includes the <span class="hlt">Yamato</span> Basin and Japan Basin. It is very important to study the crustal structure in the seismotectonic studies of the eastern margin of the Japan Sea. We conducted a marine seismic survey by using a multichannel seismic (MCS) system and ocean bottom seismographs (OBSs) along the eastern margin of the Japan Sea. Seismic data were acquired along 42 lines with a total length of approximately 9,000 km. The following results were obtained from seismic imaging. On the basis of the results of the MCS imaging, active reverse faults and folds were observed in the margin of the Toyama Trough; however, the sedimentary layers in the trough were flat. In the sedimentary layers and crusts of the Sado Ridge, Mogami Trough, and source area of the 1964 Niigata earthquake located north of the Sado Island, greater deformation was observed. The deformation weakened toward the <span class="hlt">Yamato</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015AGUFM.V21C3054S&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015AGUFM.V21C3054S&link_type=ABSTRACT"><span id="translatedtitle">Volatiles in Kimberlitic Magmas: Forced Multiple Saturation with a Mantle Source</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stamm, N.; Schmidt, M. W.</p> <p>2015-12-01</p> <p>The geochemistry and mineralogy of the mantle source for primary kimberlite melts is still very much debated, the primary melt is argued to be either of carbonatitic or kimberlitic nature and proposed melting mechanisms range from low-degree partial melting of a carbonated peridotite to high-degree melting of strongly metasomatized veins. Experimental multiple saturation of a proposed close-to-primary kimberlitic composition from Jericho (Kopylova et al. 2007, GCA) at 7 GPa shows that saturation of a <span class="hlt">lherzolitic</span> mineral assemblage occurs at 1300-1350 °C resulting in a carbonatitic melt with less than 8 wt% SiO2 and >35 wt% CO2. At higher temperatures, where the Jericho melt stays kimberlitic, it is only saturated in opx and garnet. We hence forced the close-to-primary Jericho kimberlite into multiple saturation with a <span class="hlt">lherzolitic</span> assemblage (7 GPa, 1400-1650 °C) by adding a volatile-free peridotite with the aim to saturate the system in olivine, opx, cpx and garnet. This mineral assemblage is obtained over a wide temperature range (1400-1600 °C) for a starting Jericho composition with 20-22.5 wt% CO2, H2O was kept at 0.46 wt% corresponding to the K:H ratio of phlogopite. The transition from a carbonatitic melt with ~10 wt% SiO2 and >35 wt% CO2 to a kimberlitic melt with ~27 wt% SiO2 and <25 wt% CO2 occurs from 1450 to 1600 °C. Compared to the Jericho composition, these melts have higher Na2O and lower XMg. At lower CO2 contents (10 wt%) opx was absent, while at higher CO2 (30 wt%) olivine and cpx were not stable. Kimberlitic melts in equilibrium with a <span class="hlt">lherzolite</span> are obtained for temperatures of >1500 °C, requiring a few hundred degrees more than estimated for the base of the cratonic lithosphere (1200-1400 °C at a heat flux of 40-45 mW/m2). If lower temperature carbonatites intrude into the base of the lithosphere it is questionable how these should develop into kimberlites within the lithosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009E%26PSL.283...59W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009E%26PSL.283...59W"><span id="translatedtitle">Origin of primitive high-Mg andesite: Constraints from natural examples and experiments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wood, Bernard J.; Turner, Simon P.</p> <p>2009-06-01</p> <p>The occurrence in arcs of high-magnesium andesites with Mg#'s of around 0.7 implies that such rocks are generated in, or equilibrated with, mantle peridotite under conditions which do not pertain beneath ridges. In this paper we use a review of experimental data on anhydrous peridotite melting to show that these primitive high-Mg andesites cannot be generated by anhydrous melting of <span class="hlt">lherzolite</span>. Addition of H 2O to peridotitic compositions has been shown, in numerous studies, to displace partial melts from basaltic towards more andesitic compositions leading to the possibility that high-Mg andesites are "wet" melts of <span class="hlt">lherzolite</span>. Our review of the experimental data demonstrates however, that addition of H 2O alone cannot explain the increases in both SiO 2 and MgO contents (on an anhydrous basis) required to shift from basaltic to high-Mg andesitic melts in equilibrium with <span class="hlt">lherzolite</span> residue. A much more plausible alternative is that these melts are extracted from a harzburgite residue, a model which we develop in more detail. We performed experiments at 0.6 GPa in which high Mg-andesitic melts were equilibrated with an olivine + orthopyroxene residue and find (in the absence of H 2O) that MgO and SiO 2 contents increase in the ratio 2:1 as the degree of undersaturation in clinopyroxene increases. This is the right sign and magnitude of effect to explain the compositions of primitive high-Mg andesites. Data from earlier studies of the CaO-MgO-SiO 2 system at 1 atm and natural compositions at 1.5-2 GPa are in excellent agreement with our observations. When the effects of H 2O and clinopyroxene undersaturation are added together we obtain a line in Pressure-H 2O space which describes the conditions under which a given high Mg-andesite could be in equilibrium with a harzburgite residue. Application to rocks from White Island (New Zealand), Amphlett Island (Papua New Guinea), Setouchi Belt (Japan), Mt. Shasta (USA), Adak Island and Piip volcano (Aleutians, USA) yield</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015E%26PSL.427..272S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015E%26PSL.427..272S"><span id="translatedtitle">Fe-XANES analyses of Reykjanes Ridge basalts: Implications for oceanic crust's role in the solid Earth oxygen cycle</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shorttle, Oliver; Moussallam, Yves; Hartley, Margaret E.; Maclennan, John; Edmonds, Marie; Murton, Bramley J.</p> <p>2015-10-01</p> <p>3]source) we project observed liquid compositions to an estimate of Fe2O3 in the pure enriched endmember melt, and then apply simple fractional melting models, considering <span class="hlt">lherzolitic</span> and pyroxenitic source mineralogies, to estimate [Fe2O3](source) content. Propagating uncertainty through these steps, we obtain a range of [Fe2O3](source) for the enriched melts (0.9-1.4 wt%) that is significantly greater than the ferric iron content of typical upper mantle <span class="hlt">lherzolites</span>. This range of ferric iron contents is consistent with a hybridised <span class="hlt">lherzolite</span>-basalt (pyroxenite) mantle component. The oxidised signal in enriched Icelandic basalts is therefore potential evidence for seafloor-hydrosphere interaction having oxidised ancient mid-ocean ridge crust, generating a return flux of oxygen into the deep mantle.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007Litho..94..181P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007Litho..94..181P"><span id="translatedtitle">Melt/peridotite interaction in the Southern Lanzo peridotite: Field, textural and geochemical evidence</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Piccardo, G. B.; Zanetti, A.; Müntener, O.</p> <p>2007-03-01</p> <p>This paper presents field, petrographic-structural and geochemical data on spinel and plagioclase peridotites from the southern domain of the Lanzo ophiolitic peridotite massif (Western Alps). Spinel <span class="hlt">lherzolites</span>, harzburgites and dunites crop out at Mt. Arpone and Mt. Musinè. Field evidence indicates that pristine porphyroclastic spinel <span class="hlt">lherzolites</span> are transformed to coarse granular spinel harzburgites, which are in turn overprinted by plagioclase peridotites, while strongly depleted spinel harzburgite and dunite bands and bodies replace the plagioclase peridotites. On the northern flank of Mt. Arpone, deformed, porphyroclastic (lithospheric) <span class="hlt">lherzolites</span>, with diffuse pyroxenite banding, represent the oldest spinel-facies rocks. They show microstructures of a composite subsolidus evolution, suggesting provenance from deeper (asthenospheric) mantle levels and accretion to the lithosphere. These protoliths are locally transformed to coarse granular (reactive) spinel harzburgites and dunites, which show textures reminiscent of melt/rock reaction and geochemical characteristics suggesting that they are products of peridotite interaction with reactively percolating melts. Geochemical data and modelling suggest that <1-5% fractional melting of spinel-facies DMM produced the injected melts. Plagioclase peridotites are hybrid rocks resulting from pre-existing spinel peridotites and variable enrichment of plagioclase and micro-gabbroic material by percolating melts. The impregnating melts attained silica-saturation, as testified by widespread orthopyroxene replacement of olivine, during open system migration in the lithosphere. At Mt. Musinè, coarse granular spinel harzburgite and dunite bodies replace the plagioclase peridotites. Most of these replacive, refractory peridotites have interstitial magmatic clinopyroxene with trace element compositions in equilibrium with MORB, while some Cpx have REE-depleted patterns suggesting transient geochemical features of the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1987CoMP...95..191E&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1987CoMP...95..191E&link_type=ABSTRACT"><span id="translatedtitle">Primary alkaline magmas associated with the Quaternary Alligator Lake volcanic complex, Yukon Territory, Canada</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Eiché, G. E.; Francis, D. M.; Ludden, J. N.</p> <p>1987-02-01</p> <p>The Alligator Lake complex is a Quaternary alkaline volcanic center located in the southern Yukon Territory of Canada. It comprises two cinder cones which cap a shield consisting of five distinct lava units of basaltic composition. Units 2 and 3 of this shield are primitive olivine-phyric lavas (13.5 19.5 cation % Mg) which host abundant spinel <span class="hlt">lherzolite</span> xenoliths, megacrysts, and granitoid fragments. Although the two lava types have erupted coevally from adjacent vents and are petrographically similar, they are chemically distinct. Unit 2 lavas have considerably higher abundances of LREE, LILE, and Fe, but lower HREE, Y, Ca, Si, and Al relative to unit 3 lavas. The 87Sr/86Sr and 143Nd/144Nd isotopic ratios of these two units are, however, indistinguishable. The differences between these two lava types cannot be explained in terms of low pressure olivine fractionation, and the low concentrations of Sr, Nb, P, and Ti in the granitoid xenoliths relative to the primitive lavas discounts differential crustal contamination. The abundance of spinel <span class="hlt">lherzolite</span> xenoliths and the high Mg contents in the lavas of both units indicates that their compositional differences originated in the upper mantle. The Al and Si systematics of these lavas suggests that, compared to unit 3 magmas, the unit 2 magmas may have segregated at greater depths from a garnet <span class="hlt">lherzolite</span> mantle. The identical isotopic composition and similar ratios of highly incompatible elements in these two lava units argues against their differences being a consequence of random metasomatism or mantle heterogeneity. The lower Y and HREE contents but higher concentrations of incompatible elements in the unit 2 lavas relative to unit 3 can be most simply explained by differential partial melting of similar garnet-bearing sources. The unit 2 magmas thus appear to have been generated by smaller degrees of melting at a greater depth than the unit 3 magmas. The contemporaneous eruption of two distinct but</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70012107','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70012107"><span id="translatedtitle">Composition of the earth's upper mantle-I. Siderophile trace elements in ultramafic nodules</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Morgan, J.W.; Wandless, G.A.; Petrie, R.K.; Irving, A.J.</p> <p>1981-01-01</p> <p>Seven siderophile elements (Au, Ge, Ir, Ni, Pd, Os, Re) were determined by radiochemical neutron activation analysis in 19 ultramafic rocks, which are spinel lherzollites-xenoliths from North and Central America, Hawaii and Australia, and garnet Iherzolitexenoliths from Lesotho. Abundances of the platinum metals are very uniform in spinel <span class="hlt">lherzolites</span> averaging 3.4 ?? 1.2 ppb Os, 3.7 ?? 1.1 ppb Ir, and 4.6 ?? 2.0 ppb Pd. Sheared garnet <span class="hlt">lherzolite</span> PHN 1611 has similar abundances of these elements, but in 4 granulated garnet <span class="hlt">lherzolites</span>, abundances are more variable. In all samples, the Pt metals retain cosmic ( Cl-chondrite) ratios. Abundances of Au and Re vary more than those of Pt metals, but the Au/Re ratio remains close to the cosmic value. The fact that higher values of Au and Re approach cosmic proportions with respect to the Pt metals, suggests that Au and Re have been depleted in some ultramafic rocks from an initially chondrite-like pattern equivalent to about 0.01 of Cl chondrite abundances. The relative enrichment of Au and Re in crustal rocks is apparently the result of crust-mantle fractionation and does not require a special circumstance of core-mantle partitioning. Abundances of moderately volatile elements Ni, Co and Ge are very uniform in all rocks, and are much higher than those of the highly siderophile elements Au, Ir, Pd, Os and Re. When normalized to Cl chondrites, abundances of Ni and Co are nearly identical, averaging 0.20 ?? 0.02 and 0.22 ?? 0.02, respectively; but Ge is only 0.027 ?? 0.004. The low abundance of Ge relative to Ni and Co is apparently a reflection of the general depletion of volatile elements in the Earth. The moderately siderophile elements cannot be derived from the same source as the highly siderophile elements because of the marked difference in Cl chondrite-normalized abundances and patterns. We suggest that most of the Ni, Co and Ge were enriched in the silicate by the partial oxidation of pre-existing volatile-poor Fe</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.V51E..08S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.V51E..08S"><span id="translatedtitle">Experimental determination of the H2O-undersaturated peridotite solidus</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sarafian, E. K.; Gaetani, G. A.; Hauri, E. H.; Sarafian, A. R.</p> <p>2014-12-01</p> <p>Knowledge of the H2O-undersaturated <span class="hlt">lherzolite</span> solidus places important constraints on the process of melt generation and mantle potential temperatures beneath oceanic spreading centers. The small concentration of H2O (~50-200 μg/g) dissolved in the oceanic mantle is thought to exert a strong influence on the peridotite solidus, but this effect has not been directly determined. The utility of existing experimental data is limited by a lack of information on the concentration of H2O dissolved in the peridotite and uncertainties involved with identifying small amounts of partial melt. We have developed an experimental approach for determining the peridotite solidus as a function of H2O content that overcomes these difficulties. Our initial results demonstrate that the solidus temperature for spinel <span class="hlt">lherzolite</span> containing 150 μg/g H2O is higher than existing estimates for the anhydrous solidus. Our approach to determining the H2O-undersaturated <span class="hlt">lherzolite</span> solidus is as follows. First, a small proportion (~5 %) of San Carlos olivine spheres, ~300 μm in diameter, are added to a peridotite synthesized from high-purity oxides and carbonates. Melting experiments are then conducted in pre-conditioned Au80Pd20 capsules over a range of temperatures at a single pressure using a piston-cylinder device. Water diffuses rapidly in olivine resulting in thorough equilibration between the olivine spheres and the surrounding fine-grained peridotite, and allowing the spheres to be used as hygrometers. After the experiment, the concentration of H2O dissolved in the olivine spheres is determined by secondary ion mass spectrometry. Melting experiments, spaced 20°C apart, were performed from 1250 to 1430°C at 1.5 GPa. The starting material has the composition of the depleted MORB mantle of Workman and Hart (2005) containing 0.13 wt% Na2O and 150 µg/g H2O. The concentration of H2O in the olivine spheres remains constant up to 1350°C, and then decreases systematically with increasing</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2013Litho.182..185S&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2013Litho.182..185S&link_type=ABSTRACT"><span id="translatedtitle">Petrogenesis and economic potential of the Erhongwa mafic-ultramafic intrusion in the Central Asian Orogenic Belt, NW China: Constraints from olivine chemistry, U-Pb age and Hf isotopes of zircons, and whole-rock Sr-Nd-Pb isotopes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sun, Tao; Qian, Zhuang-Zhi; Li, Chusi; Xia, Ming-Zhe; Yang, Su-Hong</p> <p>2013-12-01</p> <p>The Erhongwa mafic-ultramafic intrusion is located in the southern margin of the Central Asian Orogenic Belt in northern Xinjiang where many early-Permian mafic-ultramafic intrusions host important Ni-Cu sulfide deposits. In this paper we report zircon U-Pb age, olivine chemistry and integrated whole-rock chemical and isotopic compositions for the Erhongwa mafic-ultramafic intrusion. This intrusion is composed of <span class="hlt">lherzolites</span> and gabbroic rocks. The U-Pb age of zircon from a large olivine gabbro sample from the intrusion is 283.1 ± 1.5 Ma, which indicates that the Erhongwa intrusion is contemporaneous with the early-Permian sulfide ore-bearing mafic-ultramafic intrusions in the central Tianshan region. Olivine from the Erhongwa intrusion contains up to 89.5 mol% Fo and 3000 ppm Ni, which are the highest among all known early-Permian mafic-ultramafic intrusions in the region. The occurrence of small sulfide inclusions in the most primitive olivine and significant Ni depletion in more fractionated olivine in the Erhongwa intrusion indicate that sulfide segregation took place during olivine fractional crystallization. The Erhongwa intrusive rocks are characterized by light REE enrichment relative to heavy REE, negative Nb anomalies, positive εNd (t = 283 Ma) values from + 6.3 to + 7.7, low initial 87Sr/86Sr ratios from 0.7034 to 0.7036, initial 206Pb/204Pb ratios from 17.8 to 17.9 and zircon εHf values from 8.0 to 15.5. The Erhongwa mafic-ultramafic rocks and coeval A-type granites in the region have similar isotopic compositions but the former have lower Th/Nb ratios than the latter. These similarities and differences are consistent with the interpretation that the Erhongwa magma formed by the mixing of a mafic magma derived from a depleted mantle with a granitic melt derived from a juvenile arc crust. It is deduced that sulfide saturation in the Erhongwa magmatic system was related to the magma mixing event at depth. More significant sulfide mineralization may</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012EGUGA..14.4799K&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012EGUGA..14.4799K&link_type=ABSTRACT"><span id="translatedtitle">Selenium and Tellurium concentrations of ultradepleted peridotites determined by isotope dilution ICPMS: implications for Se-Te systematics of the Earth's mantle</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>König, S.; Luguet, A.; Lorand, J.-P.; Wombacher, F.; Lissner, M.</p> <p>2012-04-01</p> <p>As for highly siderophile elements, selenium and tellurium may constitute key tracers for planetary processes such as formation of the Earth's core and the Late Veneer composition, provided that their geochemical behaviour and abundances in the primitive upper mantle (PUM) are constrained. Within this scope, we have developed a high precision analytical method for the simultaneous determination of selenium and tellurium concentrations from a single sample aliquot and various rock matrices, including ultradepleted peridotites. The technique employs isotope dilution, thiol cotton fiber (TCF) separation and hydride generation MC-ICP-MS. A selection of international mafic and ultramafic rock reference materials BIR-1, BE-N, TDB-1, UB-N, FON B 93, BIR-1 and BHVO-2 with a range of 30 to 350 ppb Se and 0.7 to 12 ppb Te show external reproducibilities of 3 to 8% for Se and 0.4 to 11% for Te (2 relative standard deviations (r.s.d.)). We have applied this method to a suite of refractory mantle peridotites (Al2O3 <1.5 wt. %) from Lherz, previously shown to be strongly and uniformly depleted in Se, Te and incompatible elements by high degree of partial melting (20 ± 5%). In contrast to fertile <span class="hlt">lherzolites</span> which remain at broadly chondritic values (Se/Te = 9), the ultradepleted harzburgites show highly fractionated and up to suprachondritic Se/Te (< 35) that correlate with decreasing Te concentrations. The fractionation is displayed by the depleted peridotites as well as multiple analysis of a single Lherz harzburgite sample (64-3). This shows 1) a strong sample heterogeneity effect for Te and 2) a more incompatible behaviour of Te compared to Se on the whole rock scale, once base metal sulfides are highly depleted and in some cases entirely consumed by partial melting. The marked differences in Se-Te systematics observed between fertile <span class="hlt">lherzolites</span> and depleted harzburgites can be explained by the combined effect of i) different abundances and proportions of residual and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFM.V51B1674U','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFM.V51B1674U"><span id="translatedtitle">Ductile and brittle deformation in peridotite recorded in ultramafic pseudotachylytes and associated fault rocks (Balmuccia, Italian Alps)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ueda, T.; Obata, M.; Ozawa, K.; di Toro, G.</p> <p>2009-12-01</p> <p>Fault rocks exhumed from the upper mantle and the lower crust allow to investigate the mechanics of lithospheric break-up and of the ductile-brittle transition in the lithosphere. Moreover, given the large confining pressures, seismic ruptures possibly result in the production of friction melts. The study of ultramafic pseudotachylyte(PST)-bearing faults might shed some light on the mechanics of shallow mantle earthquakes. The Balmuccia peridotite massif in the Ivrea-Verbano zone, NW Italy, provides an excellent opportunity to investigate these topics. Published and very recent field and microstructural work revealed that different types of fault rocks occur in the massif, including (1) deep-seated spinel-peridotite facies mylonites with porhyroclastic texture, (2) deep-seated (recrystallized under spinel-<span class="hlt">lherzolite</span> condition) PSTs, (3) deep-seated (partially/fully recrystallized under plagioclase-<span class="hlt">lherzolite</span> condition) PSTs, (4) S-C foliated fault rock formed under plagioclase-<span class="hlt">lherzolite</span> condition and (5) relatively shallow-seated PST (they are fresh looking and preserve the pristine cooling microstructures). The occurrence of these fault rocks indicates that the Balmuccia massif contains a record of the ductile-to-brittle deformation history and associated coseismic frictional melting. Crosscutting relationships between the shear zones confirm the deformation sequence inferred from the mineral and microstructural assemblages of the different fault rock types. A mylonite shear zone with porphyroclastic texture is cut by shear zones with mylonite and recrystallized PST; the latter are cut by shear zones with an S-C foliation. In other crystralline lithologies, the S-C foliation and PSTs are typical of the brittle-ductile transition regime. The “fresh-looking” PST is believed to record the latest deformation event because glass and microlites of olivine and pigeonite (the latter is a clinopyroxene prone to break-down into other pyroxenes) are preserved in it. The</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003EAEJA....13331M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003EAEJA....13331M"><span id="translatedtitle">Formation of dunite conduits in the mantle: observations from the Lanzo peridotite in NW-Italy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Müntener, O.; Pettke, T.; Piccardo, G.; Zanetti, A.</p> <p>2003-04-01</p> <p>Mantle dunites may be the most important conduits for melt transport in the shallow upper mantle (1). Dunites as observed in the Lanzo ophiolites are generally tabular bodies with sharp, replacive contacts and are oriented parallel or discordant to the foliation in the surrounding harzburgite and plagioclase <span class="hlt">lherzolites</span> (2, 3). In order to evaluate the mechanisms of how dunite formed, we examined in detail dunite - plagioclase <span class="hlt">lherzolite</span> transects by a combined field, electron microprobe and Laser ablation ICP-MS study. Field observations show that some discordant dunites locally contain small interstitial clinopyroxene, and large clinopyroxene megacrysts sometimes associated with plagioclase. Calculated liquids in equilibrium with clinopyroxenes have REE slopes and concentrations similar to MORB crystallised from low percentage aggregate liquids (less than 5%). In addition spinel in Lanzo dunite is similar to spinels from MORB (4), with high TiO2 and elevated Cr#. Preliminary results on a dunite transect containing a small gabbro dikelet in its center indicate, however, that spinel compositions consistently vary perpendicular to the contact. The Cr#, TiO2 and a number of trace elements (Zn, Co V, Cr, Mn) decrease with increasing distance from the medial gabbro, while Ni increases. In addition, spinels far from the medial gabbro rarely contain inclusions of primary hydrous phases (pargasite and phlogopite). Compositional variations in olivine are more subtle, e.g. contents of compatible trace elements (Co, Ni) are systematically lower in dunite olivine than in olivine from plagioclase <span class="hlt">lherzolite</span>. The observed spatial chemical variations may reflect melt focussing with time even within a single dunite conduit. These data might be used to place constraints on the relative importance of focused porous flow vs cracks in the shallow mantle. 1. Kelemen, P. B., Hirth, G., Shimizu, N., Spiegelman, M. &Dick, H. J. B. (1997) Philosophical Transactions of the Royal Society of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016IJEaS.tmp...53A&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016IJEaS.tmp...53A&link_type=ABSTRACT"><span id="translatedtitle">Nature and evolution of lithospheric mantle beneath the southern Ethiopian rift zone: evidence from petrology and geochemistry of mantle xenoliths</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Alemayehu, Melesse; Zhang, Hong-Fu; Sakyi, Patrick Asamoah</p> <p>2016-06-01</p> <p>Mantle xenoliths hosted in Quaternary basaltic lavas from the Dillo and Megado areas of the southern Ethiopian rift are investigated to understand the geochemical composition and associated processes occurring in the lithospheric mantle beneath the region. The xenoliths are comprised of predominantly spinel <span class="hlt">lherzolite</span> with subordinate harzburgite and clinopyroxenite. Fo content of olivine and Cr# of spinel for peridotites from both localities positively correlate and suggest the occurrence of variable degrees of partial melting and melt extraction. The clinopyroxene from <span class="hlt">lherzolites</span> is both LREE depleted (La/Sm(N) = 0.11-0.37 × Cl) and LREE enriched (La/Sm(N) = 1.88-15.72 × Cl) with flat HREEs (Dy/Lu(N) = 0.96-1.31 × Cl). All clinopyroxene from the harzburgites and clinopyroxenites exhibits LREE-enriched (La/Sm(N) = 2.92-27.63.1 × Cl and, 0.45 and 1.38 × Cl, respectively) patterns with slight fractionation of HREE. The 143Nd/144Nd and 176Hf/177Hf ratios of clinopyroxene from <span class="hlt">lherzolite</span> range from 0.51291 to 0.51370 and 0.28289 to 0.28385, respectively. Most of the samples define ages of 900 and 500 Ma on Sm-Nd and Lu-Hf reference isochrons, within the age range of Pan-African crustal formation. The initial Nd and Hf isotopic ratios were calculated at 1, 1.5, 2 and 2.5 Ga plot away from the trends defined by MORB, DMM and E-DMM which were determined from southern Ethiopian peridotites, thus indicating that the Dillo and Megado xenoliths could have been produced by melt extraction from the asthenosphere during the Pan-African orogenic event. There is no significant difference in 87Sr/86Sr ratios between the depleted and enriched clinopyroxene. This suggests that the melts that caused the enrichment of the clinopyroxene are mainly derived from the depleted asthenospheric mantle from which the xenoliths are extracted. Largely, the mineralogical and isotopic compositions of the xenoliths show heterogeneity of the CLM that could have been produced from various</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.V33C2890S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.V33C2890S"><span id="translatedtitle">Formation of plagioclase-bearing peridotite and a peridotite-wehrlite-gabbro suite through melt-rock reaction: An experimental study</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Saper, L.; Liang, Y.</p> <p>2012-12-01</p> <p>Plagioclase-bearing peridotites are observed among abyssal peridotites, massif peridotites, and mantle sections of ophiolites of <span class="hlt">lherzolite</span> subtype. Formation of plagioclase-bearing peridotites is often attributed to basalt impregnation into host harzburgite or <span class="hlt">lherzolite</span> in a thermal boundary layer. During transport through asthenospheric mantle, melt generated in the deep mantle will inevitably interact with the overlying mantle column through reactive dissolution and may leave geochemical imprints on plagioclase-bearing peridotites. To assess the role of melt-rock reaction on the formation of plagioclase-bearing peridotites and its implications for lithosphere composition, we conducted dissolution experiments in which a 88% spinel <span class="hlt">lherzolite</span> + 12% basalt starting mixture was juxtaposed against a primitive MORB in a graphite-lined molybdenum capsule. The reaction couples were run at 1300°C and 1 GPa for 1 or 24 hrs, and then stepped cooled to 1050°C and 0.7 GPa over the next several days. Cooling promotes in situ crystallization of interstitial melts, allowing us to better characterize the mineral compositional trends produced and observed by melt-rock reaction and crystallization. A gabbro and a plagioclase-bearing peridotite were observed in the two halves of the reaction couple after the experiments were completed. The peridotite from the 24 hr reaction experiment is mostly composed of subhedral to euhedral olivines (10-50 μm in size, Mg# 75-83), poikilitic clinopyroxene (~100 μm in size, Mg# 73-83) with olivine and spinel chadocrysts, and interstitial plagioclase (An# 68-78) and melt. In a control experiment quenched after a 24 hour reaction at 1300°C the basalt completely dissolved the pyroxenes and spinels leaving a residue of rounded olivine grains (10-100 μm in size) surrounded by a relatively large melt fraction. Textural results from the step-cooling experiments suggest the following crystallization sequence from the olivine+melt mush: olivine</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002EGSGA..27.6513A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002EGSGA..27.6513A"><span id="translatedtitle">Mantle Evolution Beneath The Colorado Palteau: Interpreta-tion of The Study of Mineral Concentrate From Kimberlite Pipe Kl-1 Colorado.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ashchepkov, I.; Vladykin, N.; Mitchell, R.; Coopersmith, H.; Garanin, V.; Saprykin, A. I.; Khmelnikova, O. S.</p> <p></p> <p>Mineral grains and their intergrowth from the concentrate form the KL1- kimberlite pipe Colorado plateau was analyzed by EPMA and LAM ICP MS in Analytic Center of UIGGM. Garnets reveal nearly continuous trend of the compositions divided into 5 intervals. 1 cumulates from the crust and Sp facie mantle; 2. Gar-Sp <span class="hlt">lherzolites</span>; 3- Gar- wehrlites, <span class="hlt">lherzolites</span> and harzburgites; 4- Gar <span class="hlt">lherzolites</span> and harzburgites; 4. Pyroxenites and Il peri-dotites . They reveal three trend of Ti decrease with the ris- ing Cr content. Those in the inter-growth with the pyroxenes are less in Tio2 as well as the pyroxenes. Discrete large Cpx grains are richer in Na, Al, Cr. TP conditions determined for the clinopyroxenes with Nimis- Taylor, 2001 thermobarometer and barometer Ashchepkov, 2001 reveal the heating from 35 to 40-42 mv/m2 in 30-50kbar interval. The spinels show two compositional intervals 64-50% Cr2O3 and 47-30%. The branch with the essential enrichment to 8% TiO2with the Cr decrease what also suppose the peridotite alteration due to rising of evolving Ti-rich melts. Two descend- ing crystallization lines for the ilmenites suggest the (polybaric) differentiation in two magmatic chambers. The Cr-rich ilmenites and most Cr-rich subcalcis garnets were found in the serpentinized ilmenite harzburgites that probably surround the most deep mag-matic chamber. The Ilm -Q (coesite) intergrowth suggests the deep differenti- ation. Several ilmenites contain up to 11%MnO. Trace elements determined for the clinopyroxenes suppose small decree melting possibly under influence of subducted- related melts having definite U peak and Ta-Nb minimums. Their reaction with peri- dotites with garnet dissolution according to AFC model decrease La/Ybn ration as well as the Pb* and U peak. Two stages of the Ti-rich melt percolations suggested to be accompanied the plum- re-lated melts influence on the peridotite of Wyoming craton keel which was followed with fur-ther followed by submelting of the subducted</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110014358','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110014358"><span id="translatedtitle">The 100th Anniversary of the Fall of Nakhla: The Subdivision of BM1913,25</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>McBridge, Kathleen M.; Righter, K.</p> <p>2011-01-01</p> <p> <span class="hlt">Yamato</span> and four from Miller Range regions in Antarctica. The <span class="hlt">Yamato</span> Nakhlites are paired as are the Miller Range samples.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_24 --> <div id="page_25" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="481"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMMR44A..03B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMMR44A..03B"><span id="translatedtitle">XANES Measurements of Cr Valence in Olivine and their Applications to Planetary Basalts (Invited)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bell, A. S.; Burger, P.; Le, L.; Shearer, C. K.; Papike, J.; Sutton, S. R.; Newville, M.; Jones, J. H.</p> <p>2013-12-01</p> <p>The oxidation state and partitioning behavior of trace Cr in terrestrial and planetary basaltic magmas has long been a subject of petrologic inquiry. We have performed a series of experiments designed to examine the relationship between oxygen fugacity and the ratio of divalent to trivalent Cr present in olivine crystals grown from a basaltic liquid. The experimental olivine crystals were grown at fO2 values ranging from IW-1 to IW+3.4. The melt composition used in this work was modeled after the bulk composition of the primitive, basaltic martian meteorite <span class="hlt">Yamato</span> 980459 (Y-98). Chromium valence in the olivine crystals was measured with X-ray-Absorption-Near-Edge-Spectroscopy (XANES) at the Advanced Photon Source, Argonne National Laboratory. Chromium K-edge XANES data were acquired with the x-ray microprobe of GSECARS beamline 13-ID-E. Beam focusing was accomplished with dynamically-figured Kirkpatrick-Baez focusing mirrors; this configuration yielded a beam focused to a final spot size of ~ 4 μm2. Results from the XANES measurements indicate that the ratio of divalent to trivalent Cr in the olivine is systematically correlated with fO2 in a manner that is consistent with the expected redox systematics for Cr2+- Cr3+ in the melt. In this way, measurements of the Cr2+/Cr3+ in olivine phenocrysts can indirectly reveal information about the Cr valence ratio and fO2 the liquid from which it grew even in the absence of a quenched melt phase. Although the results from the experiments presented in this work specifically apply to the <span class="hlt">Yamato</span> 98 parental liquid, the concepts and XANES analytical techniques used in this study present a novel, generalized methodology that may be applicable to any olivine-bearing basalt. Furthermore, the XANES based measurements are made on a micron-scale, thus potential changes of the Cr2+/Cr3+ in the melt occurring during crystallization may be recorded in detail.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5688591','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5688591"><span id="translatedtitle">Petrological characteristics of the Masontown, Pennsylvania kimberlite dike</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Prellwitz, H.S.; Bikerman, M. . Dept. of Geology and Planetary Science)</p> <p>1993-03-01</p> <p>The Masontown, PA, kimberlite dike intrudes flat-lying Pennsylvanian and ea