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Carbonates in the Kaidun chondriteKaidun is a remarkable chondrite breccia fall containing lithic clasts that span a wide range of chondrite groups including C and E chondrites, as well as having clasts with characteristics not yet found in existing chondrite samples. The dominant lithology in Kaidun appears to be CR chondritic, consonant with recent O isotope data. The carbonates in Kaidun are presented as one mineralogical basis for comparing it to the other hydrated chondrites and to better understand its relative alteration history. The four polished thin sections of Kaidun studied contained a variety of lithologies that we classified into four groups -- CR, E, CM-like, and dark inclusions (DIs). DIs contain sulfide and magnetite morphologies that superficially resemble CI chondrites, and some of the previously reported CI lithologies in Kaidun may be what we term DIs. Carbonates were found in all lithologies studied. Carbonates in Kaidun are similar in composition to those in CR chondrites. Some of the DIs in Kaidun, previously characterized as CI, have carbonates similar to those in CR chondrites and are unlike those in CI or CM chondrites. Most carbonates in Kaidun and CR chondrites are calcites, some of which formed at temperatures above 250 C. Dolomite is less common and some may be metastable. Alteration temperatures in the Renazzo CR chondrite were estimated to be approximately 300 C, based on O isotope fractionation between phyllosilicates and magnetite. Temperatures of up to 450 C were proposed for the alteration of a CR-like dark inclusion in Kaidun, based on the presence of hydrothermal pentlandite veins. The alteration temperatures for Kaidun and the other CR chondrites are considerably higher than those suggested for CI or CM parent bodies.
Document ID
19950042279
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Weisberg, M. K.
(American Museum of Natural History, New York, NY US, United States)
Prinz, M.
(American Museum of Natural History, New York, NY US, United States)
Zolensky, M. E.
(NASA Johnson Space Center Houston, TX, US, United States)
Ivanov, A. V.
(Russian Academy of Science Moscow, Russia)
Date Acquired
August 16, 2013
Publication Date
July 1, 1994
Publication Information
Publication: Meteoritics
Volume: 29
Issue: 4
ISSN: 0026-1114
Subject Category
Lunar And Planetary Exploration
Accession Number
95A73878
Distribution Limits
Public
Copyright
Other

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