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1.
Zoltn Vci Carl B. Agee Munir Humayun Karen Ziegler Yemane Asmerom Victor Polyak Henner Busemann Daniela Krietsch Matthew Heizler Matthew E. Sanborn Qing‐Zhu Yin 《Meteoritics & planetary science》2020,55(3):622-648
Northwest Africa (NWA) 11042 is a heavily shocked achondrite with medium‐grained cumulate textures. Its olivine and pyroxene compositions, oxygen isotopic composition, and chromium isotopic composition are consistent with L chondrites. Sm‐Nd dating of its primary phases shows a crystallization age of 4100 ± 160 Ma. Ar‐Ar dating of its shocked mineral maskelynite reveals an age of 484.0 ± 1.5 Ma. This age coincides roughly with the breakup event of the L chondrite parent body evident in the shock ages of many L chondrites and the terrestrial record of fossil L chondritic chromite. NWA 11042 shows large depletions in siderophile elements (<0.01×CI) suggestive of a complex igneous history involving extraction of a Fe‐Ni‐S liquid on the L chondrite parent body. Due to its relatively young crystallization age, the heat source for such an igneous process is most likely impact. Because its mineralogy, petrology, and O isotopes are similar to the ungrouped achondrite NWA 4284 (this work), the two meteorites are likely paired and derived from the same parent body. 相似文献
2.
Wintertime observations of mesoscale cellular convection (MCC) over the East China Sea have resulted in criteria that have a remarkable similarity to those reported by Woodcock (1975) in the study of thermals and gull flight behavior. It has been determined that the surface wind speed (V) and the air-sea temperature difference (T) prescribe unique and compatible conditons for both the occurrence of MCC and soaring by sea gulls. Specifically, the onset of MCC when V is between 5 and 9 m s–1 is inversely proportional to T in the range 5 to 7 °C. Elsewhere, the onset of MCC occurs under conditions of direct proportionality between V and T. Necessary conditions for the occurrence of MCC due to heating from below are T 5 °C and V 5 m s–1. The boundaries of the convective regime for MCC are discussed and interpreted in accordance with the regime for sea-gull soaring and similarity concepts. 相似文献
3.
Carl Agee 《Meteoritics & planetary science》2017,52(8):1758-1760
4.
Zoltn Vci Carl B. Agee Christopher D. K. Herd Erin Walton Oliver Tschauner Karen Ziegler Vitali B. Prakapenka Eran Greenberg Sylvia Monique‐Thomas 《Meteoritics & planetary science》2020,55(5):1011-1030
Hydrous alteration of olivine macrocrysts in a Martian olivine phyric basalt, NWA 10416, and a terrestrial basalt from southern Colorado are examined using SEM, EPMA, TEM, and µXRD techniques. The olivines in the meteorite contain linear nanotubes of hydrous material, amorphous areas, and fluid dissolution textures quite distinct from alteration identified in other Martian meteorites. Instead, they bear resemblance to terrestrial deuteric alteration features. The presence of the hydrous alteration phase Mg‐laihunite within the olivines has been confirmed by µXRD analysis. The cores of the olivines in both Martian and terrestrial samples are overgrown by unaltered rims whose compositions match those of a separate population of groundmass olivines, suggesting that the core olivines are xenocrysts whose alteration preceded crystallization of the groundmass. The terrestrial sample is linked to deep crustal metasomatism and the “ignimbrite flare‐up” of the Oligocene epoch. The comparison of the two samples suggests the existence of an analogous relatively water‐rich magmatic reservoir on Mars. 相似文献
5.
Christina L. Tague Shirley A. Papuga Cynthia Gerlein-Safdi Salli Dymond Ryan R. Morrison Elizabeth W. Boyer Diego Riveros-Iregui Elizabeth Agee Bhavna Arora Yannis G. Dialynas Amy Hansen Stefan Krause Sylvain Kuppel Steven P Loheide II Stanislaus J. Schymanski Samuel C Zipper 《水文研究》2020,34(7):1665-1673
6.
Alex Ruzicka Jeffrey Grossman Audrey Bouvier Christopher D. K. Herd Carl B. Agee 《Meteoritics & planetary science》2015,50(9):1661-1661
Meteoritical Bulletin 101 contains 2639 meteorites accepted by the Nomenclature Committee in 2012, including 1 fall (Battle Mountain), with 2308 ordinary chondrites, 156 carbonaceous chondrites, 63 HED achondrites, 17 relict meteorites, 16 Rumuruti chondrites, 15 enstatite chondrites, 15 ureilites, 10 iron meteorites, 9 lunar meteorites, 9 primitive achondrites, 8 ungrouped achondrites, 7 mesosiderites, 4 Martian meteorites, and 2 Pallasites, and with 1812 from Antarctica, 437 from Asia, 301 from Africa, 43 from South America, 21 from Europe (including Russia), 21 from North America, 3 from Oceania, and 1 from unknown. Information about approved meteorites can be obtained from the Meteoritical Bulletin Database (MBD) available on line at http://www.lpi.usra.edu/meteor/ . 相似文献
7.
Microbial mercury (Hg) methylation and methylmercury (MeHg) degradation processes were examined using radiolabled model Hg
compounds in San Francisco Bay-Delta surface sediments during three seasonal periods: late winter, spring, and fall. Strong
seasonal and spatial differences were evident for both processes. MeHg production rates were positively correlated with microbial
sulfate reduction rates during late winter only. MeHg production potential was also greatest during this period and decreased
during spring and fall. This temporal trend was related both to an increase in gross MeHg degradation, driven by increasing
temperature, and to a build-up in pore water sulfide and solid phase reduced sulfur driven by increased sulfate reduction
during the warmer seasons. MeHg production decreased sharply with depth at two of three sites, both of which exhibited a corresponding
increase in reduced sulfur compounds with depth. One site that was comparatively oxidized and alkaline exhibited little propensity
for net MeHg production. These results support the hypothesis that net MeHg production is greatest when and where gross MeHg
degradation rates are low and dissolved and solid phase reduced sulfur concentrations are low. 相似文献
8.
Trace element analyses of 1-atm and high-pressure experiments show that in komatiite and peridotite, the olivine (OL)/liquid (L) distribution coefficient for Al2O3 (
) increases with pressure and temperature. Olivine in equilibrium with liquid accepts as much as 0.2 wt% Al2O3 in solution at 6 GPa. Convergence to equilibrium compositions at this high level is shown by cation diffusion of Al into synthetic forsterite crystals of low-Al contents in the presence of melt. Convergence to low-Al equilibrium compositions at lower P and T is shown by diffusion of Al out of synthetic forsterite with high initial Al content. Isobaric and isothermal experimental data subsets reveal that temperature and pressure variations both have real effects on
. Variation in silicate melt composition has no detectable effect on
within the limited range of experimentally investigated mixtures. Least-squares regression for 24 experiments, using komatiite and peridotite, performed at 1 atm to 6 GPa and 1300 to 1960°C, gives the best fit equation:
Increase in
with increasingly higher-pressure melting is consistent with incorporation of a spinel-like component of low molar volume into olivine, although other substitutions possibly involving more complex coupling cannot be ruled out. High P-T ultrabasic melting residues, if pristine, may be recognized by the high
calculated from microprobe analyses of Al2O3 concentrations in residual olivines and estimated Al2O3 concentration in the last liquid removed. In general the low levels of Al in natural olivine from mantle xenoliths suggest that pristine residues are rarely recovered. 相似文献
9.
Alex Ruzicka Jeffrey Grossman Audrey Bouvier Carl B. Agee 《Meteoritics & planetary science》2017,52(5):1014-1014
Meteoritical Bulletin 103 contains 2582 meteorites including 10 falls (Ardón, Demsa, Jinju, Kri?evci, Kuresoi, Novato, Tinajdad, Tirhert, Vicência, Wolcott), with 2174 ordinary chondrites, 130 HED achondrites, 113 carbonaceous chondrites, 41 ureilites, 27 lunar meteorites, 24 enstatite chondrites, 21 iron meteorites, 15 primitive achondrites, 11 mesosiderites, 10 Martian meteorites, 6 Rumuruti chondrites, 5 ungrouped achondrites, 2 enstatite achondrites, 1 relict meteorite, 1 pallasite, and 1 angrite, and with 1511 from Antarctica, 588 from Africa, 361 from Asia, 86 from South America, 28 from North America, and 6 from Europe. Note: 1 meteorite from Russia was counted as European. The complete contents of this bulletin (244 pages) are available on line. Information about approved meteorites can be obtained from the Meteoritical Bulletin Database (MBD) available on line at http://www.lpi.usra.edu/meteor/ . 相似文献
10.
Alex Ruzicka Jeffrey Grossman Audrey Bouvier Christopher D. K. Herd Carl B. Agee 《Meteoritics & planetary science》2015,50(9):1662-1662
Meteoritical Bulletin 102 contains 3141 meteorites including 12 falls (Boumdeid (2003), Boumdeid (2011), Braunschweig, Chelyabinsk, Dongyang, Draveil, Heyetang, Indian Butte, Katol, Ladkee, Ouadangou, Xining), with 2611 ordinary chondrites, 264 HED achondrites, 124 carbonaceous chondrites, 30 ureilites, 20 Martian meteorites, 16 primitive achondrites, 16 Rumuruti chondrites, 15 mesosiderites, 12 iron meteorites, 10 lunar meteorites, 9 enstatite chondrites, 4 enstatite achondrites, 4 Pallasites, 4 ungrouped achondrites, and 2 angrites, and with 1708 from Antarctica, 956 from Africa, 294 from South America, 126 from Asia, 47 from North America, 6 from Europe (including Russia), and 4 from Oceania. Information about approved meteorites can be obtained from the Meteoritical Bulletin Database (MBD) available on line at http://www.lpi.usra.edu/meteor/ . 相似文献