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Almahata Sitta-Fragment MS-CH: Characterization of a new chondrite type.
- Source :
-
Meteoritics & Planetary Science . Oct2010, Vol. 45 Issue 10/11, p1657-1667. 11p. 2 Color Photographs, 1 Black and White Photograph, 4 Charts, 2 Graphs. - Publication Year :
- 2010
-
Abstract
- - Among the several hundred, mostly small meteorite fragments, recovered within the Almahata Sitta strewn field, one fragment (MS-CH), weighing 5.68 g, was detected that represents a new type of chondritic meteorite. The detection of short-lived cosmogenic radionuclides clearly indicates that this chondrite fragment results from a fresh meteorite fall consistent with the Almahata Sitta event in October 2008. The fundamental mineralogical characteristics of the Almahata Sitta fragment MS-CH can be summarized as follows: (1) the almost equilibrated olivine has high Fa contents of about 36 mole%. The fragment is of petrologic type 3.8 ± 0.1; (2) the metal abundance of the rock is on the order of 2.5 vol%; (3) the mean chondrule size has been determined to be roughly 450 μm; (4) point-counting and imaging indicate that the matrix abundance is approximately 45 vol%; (5) Cr-spinels have much lower TiO2 concentrations than typical spinels within R chondrites; (6) calcium-aluminum-rich inclusions are spinel-rich and severely altered having abundant Na- and/or Cl-rich alteration products. Spinel also contains significant concentrations of Fe and Zn; (7) magnetites and platinum-group element-rich phases (sulfides, tellurides, and arsenides) characteristic of both R and CK chondrites were not found in fragment MS-CH; and (8) the mean oxygen isotope composition of three small fragments of Almahata Sitta MS-CH is δ17O = +4.35‰, δ18O = +4.94‰, and Δ17O = +1.76‰. The oxygen isotopes relate MS-CH to R chondrites. No established chondrite group having all these characteristics exists. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 10869379
- Volume :
- 45
- Issue :
- 10/11
- Database :
- Academic Search Index
- Journal :
- Meteoritics & Planetary Science
- Publication Type :
- Academic Journal
- Accession number :
- 65028356
- Full Text :
- https://doi.org/10.1111/j.1945-5100.2010.01107.x