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41.
The compositions of coexisting orthopyroxene, clinopyroxene and garnet in the CaO-MgO-Al2O3-SiO2 system are fixed at any givenP andT. Reversed hydrothermal experiments over theP/T range 15–40 kb/900°–l,100° C indicate that the garnet composition is nearly constant at Py86Gr14; the Alcontent and Ca/Ca+Mg values of the pyroxenes vary significantly, however:
T 相似文献
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Effect of Sewage Sludge on Formation of Acidic Ground Water at a Reclaimed Coal Mine 总被引:1,自引:0,他引:1
Charles A. Cravotta III 《Ground water》1998,36(1):9-19
44.
M. S. Westmoquette L. J. Smith J. S. Gallagher III K. M. Exter † 《Monthly notices of the Royal Astronomical Society》2007,381(3):913-931
We present a set of four Gemini-North Multi-Object Spectrograph/integral field unit (IFU) observations of the central disturbed regions of the dwarf irregular starburst galaxy NGC 1569, surrounding the well-known superstar clusters A and B. This continues on directly from a companion paper, in which we describe the data reduction and analysis techniques employed and present the analysis of one of the IFU pointings. By decomposing the emission-line profiles across the IFU fields, we map out the properties of each individual component identified and identify a number of relationships and correlations that allow us to investigate in detail the state of the ionized interstellar medium (ISM). Our observations support and expand on the main findings from the analysis of the first IFU position, where we conclude that a broad (≲400 km s
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Katrina D. van Drongelen Douglas Rumble III Kimberly T. Tait 《Meteoritics & planetary science》2016,51(6):1184-1200
Northwest Africa (NWA) 5232, an 18.5 kg polymict eucrite, comprises eucritic and exogenic CM carbonaceous chondrite clasts within a clastic matrix. Basaltic clasts are the most abundant eucritic clast type and show a range of textures and grain size, from subophitic to granoblastic. Other eucritic clast types present include cumulate (high‐En pyroxene), pyroxene‐lath, olivine rich with symplectite intergrowths as a break‐down product of a quickly cooled Fe‐rich metastable pyroxferroite, and breccia (fragments of a previously consolidated breccia) clasts. A variable cooling rate and degree of thermal metamorphism, followed by a complex brecciation history, can be inferred for the clasts based on clast rounding, crystallization (and recrystallization) textures, pyroxene major and minor element compositions, and pyroxene exsolution. The range in δ18O of clasts and matrix of NWA 5232 reflects its origin as a breccia of mixed clasts dominated by eucritic lithologies. The oxygen isotopic compositions of the carbonaceous chondrite clasts identify them as belonging to CM group and indicate that these clasts experienced a low degree of aqueous alteration while part of their parent body. The complex evolutionary history of NWA 5232 implies that large‐scale impact excavation and mixing was an active process on the surface of the HED parent body, likely 4 Vesta. 相似文献
48.
Neyda M. ABREU Frans J. M. RIETMEIJER Joseph A. NUTH III 《Meteoritics & planetary science》2011,46(8):1082-1096
Abstract– We have experimentally produced nanophase sulfide compounds and magnetite embedded in Si‐rich amorphous materials by flash‐cooling of a gas stream. Similar assemblages are ubiquitous, and often dominant components of samples of impact‐processed silica aerogel tiles and submicron grains from comet 81P/Wild 2 were retrieved by NASA’s Stardust mission. Although the texture and compositions of nanosulfide compounds have been reproduced experimentally, the mechanisms of formation of these minerals and their relationship with the surrounding amorphous materials have not been established. In this study, we present evidence that both of these materials may not only be produced through cooling of a superheated liquid but they may have also been formed simultaneously by flash‐cooling and subsequent deposition of a gas dominated by Fe‐S‐SiO‐O2. In a dust generator at the Goddard Space Flight Center, samples are produced by direct gas‐phase condensation from gaseous precursors followed by deposition, which effectively isolates the effects of gas‐phase reactions from the effects of melting and condensation. High‐resolution transmission electron microscopy images and energy‐dispersive spectroscopy analysis show that these experiments replicate key features of materials from type B and type C Stardust tracks, including textures, distribution of inclusions, nanophase size, and compositional diversity. We argue that gas‐phase reactions may have played a significant role in the capture environment for nanophase materials. Our results are consistent with a potential progenitor assemblage of micron and submicron‐sized sulfides and submicron silica‐bearing phases, which are commonly observed in chondritic interplanetary dust particles and in the matrices of the most pristine chondritic meteorites. 相似文献
49.
Andrew W. BECK David W. MITTLEFEHLDT Harry Y. McSWEEN Jr Douglas RUMBLE III Cin‐Ty A. LEE Robert J. BODNAR 《Meteoritics & planetary science》2011,46(8):1133-1151
Abstract– The absence of dunite (>90 vol% olivine) in the howardite, eucrite, and diogenite (HED) meteorite suite, when viewed with respect to spectroscopic and petrologic evidence for olivine on Vesta, is problematic. Herein, we present petrologic, geochemical, and isotopic evidence confirming that Miller Range (MIL) 03443, containing 91 vol% olivine, should be classified with the HED clan rather than with mesosiderites. Similarities in olivine and pyroxene FeO/MnO ratios, mineral compositions, and unusual mineral inclusions between MIL 03443 and the diogenites support their formation on a common parent body. This hypothesis is bolstered by oxygen isotopic and bulk geochemical data. Beyond evidence for its reclassification, we present observations and interpretations that MIL 03443 is probably a crustal cumulate rock like the diogenites, rather than a sample of the Vestan mantle. 相似文献
50.
Jutta ZIPFEL Bradley L. JOLLIFF Ralf GELLERT Kenneth E. HERKENHOFF Rudolf RIEDER Robert ANDERSON James F. BELL III Johannes BRÜCKNER Joy A. CRISP Philip R. CHRISTENSEN Benton C. CLARK Paulo A.
De SOUZA Jr. Gerlind DREIBUS Claude
D’USTON Thanasis ECONOMOU Steven P. GOREVAN Brian C. HAHN Göstar KLINGELHÖFER Timothy J. McCOY Harry Y. McSWEEN Jr. Douglas W. MING Richard V. MORRIS Daniel S. RODIONOV Steven W. SQUYRES Heinrich WÄNKE Shawn P. WRIGHT Michael B. WYATT Albert S. YEN 《Meteoritics & planetary science》2011,46(1):1-20
Abstract– The Opportunity rover of the Mars Exploration Rover mission encountered an isolated rock fragment with textural, mineralogical, and chemical properties similar to basaltic shergottites. 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 shergottites, 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 shergottite meteorites from Mars. 相似文献
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