نتایج جستجو برای: enstatite
تعداد نتایج: 374 فیلتر نتایج به سال:
An Almahata Sitta EL3 fragment: implications for the complex thermal history of enstatite chondrites
Abstract Almahata Sitta is a polymict breccia, consisting of many kinds clasts. Here we present our mineralogical and petrological results on an EL3 fragment, MS-177 from Sitta. This fragment shows typical type 3 chondritic texture, well-defined chondrules, isolated silicate minerals, opaque nodules. Most chondrules are enstatite-rich with some having olivine. Although these components chondrit...
X-ray fluorescence spectra obtained by the MESSENGER spacecraft orbiting Mercury indicate that the planet's surface differs in composition from those of other terrestrial planets. Relatively high Mg/Si and low Al/Si and Ca/Si ratios rule out a lunarlike feldspar-rich crust. The sulfur abundance is at least 10 times higher than that of the silicate portion of Earth or the Moon, and this observat...
Murrell and Burnett (M-B) ( 1982) reported that oldhamite (CaS) is the primary host phase ofU and Th in the E6 chondrites. E-chondrite Th/U values were all cosmic, indicating a lack of Th-U fractionation in both oldhamite and in the bulk meteorites. In Khairpur (E6), they attributed excess fossil fission tracks to the presence of Pu in oldhamite. Rare earth (REE) enrichments were inferred for a...
Introduction: CM carbonaceous chondrites display a wide range of aqueous alteration products that occurred by low temperature water-rock reactions on their parent bodies [1,2]. Previous modeling studies have verified that these reactions occurred at low temperatures (0-50C), for they reproduced many of the observed mineral assemblages [3]. The dominant phases are tochilinite and Mg-Fe phyllosil...
Chondrites are sediments of materials left over from the earliest stage solar system history. Based on their undifferentiated nature and less fractionated chemical compositions, chondrites widely considered to represent unprocessed building blocks terrestrial planets embryos. Models composition generally find chondritic relative abundances refractory lithophile elements (RLE) in bulk bodies ("c...
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