Universität zu Köln

Friend, Pia ORCID: 0000-0002-9042-3300, Hezel, Dominik C., Barrat, Jean-Alix ORCID: 0000-0003-3158-3109, Zipfel, Jutta, Palme, Herbert and Metzler, Knut (2018). Composition, petrology, and chondrule-matrix complementarity of the recently discovered Jbilet Winselwan CM2 chondrite. Meteorit. Planet. Sci., 53 (12). S. 2470 - 2492. HOBOKEN: WILEY. ISSN 1945-5100

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Abstract

Jbilet Winselwan (JW) is a recently found CM2 chondrite breccia containing two lithologies. A study of 508 chondrules provides the first statistically reliable size distribution for CM chondrite chondrules, which is about log normal with a mean chondrule size of 149 mu m (lithology I) and 141 mu m (lithology II). Chondrules are surrounded by fine-grained rims. Apparent chondrule diameters and their apparent rim thicknesses are positively correlated with slopes of 0.12 (lithology II) and 0.18 (lithology I), the latter typical of CM chondrites. The CM chondrites are generally primitive and parts of JW experienced only mild aqueous alteration. Bulk JW element ratios are solar (=CI chondritic), e.g., Si/Mg (1.12), Fe/Mg (1.80-1.83), Ti/Al (0.053), and about solar for Ca/Al. The 26 chemically studied chondrules have subchondritic Si/Mg (0.88) and Fe/Mg ratios (0.21). Matrix and the fine-grained chondrule rims on the other hand have superchondritic Si/Mg ratios with means of 1.34 and 1.41, respectively. The Fe/Mg ratios are also superchondritic, with means of 2.41 (matrix) and 2.61 (fine-grained rims). The refractory element ratios in chondrules are superchondritic (Ti/Al: 0.106; Ca/Al: 1.64), and subchondritic in the JW matrix (Ti/Al: 0.031; Ca/Al: 0.71) and in the fine-grained rims (Ti/Al: 0.023; Ca/Al: 0.68). These complementary element ratios require formation of chondrules and matrix/rims from the same reservoir in order to obtain a chondritic bulk composition. Most chondrules are mineralogically zoned, with olivine in the core and low-Ca pyroxene in the rim; hence, CM chondrules were open systems, exchanging material with the surrounding gas.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Friend, Pia UNSPECIFIED orcid.org/0000-0002-9042-3300 UNSPECIFIED Hezel, Dominik C. UNSPECIFIED UNSPECIFIED UNSPECIFIED Barrat, Jean-Alix UNSPECIFIED orcid.org/0000-0003-3158-3109 UNSPECIFIED Zipfel, Jutta UNSPECIFIED UNSPECIFIED UNSPECIFIED Palme, Herbert UNSPECIFIED UNSPECIFIED UNSPECIFIED Metzler, Knut UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-164090
DOI:	10.1111/maps.13139
Journal or Publication Title:	Meteorit. Planet. Sci.
Volume:	53
Number:	12
Page Range:	S. 2470 - 2492
Date:	2018
Publisher:	WILEY
Place of Publication:	HOBOKEN
ISSN:	1945-5100
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language FINE-GRAINED RIMS; ISOTOPE COMPOSITION; AQUEOUS ALTERATION; CARBONACEOUS CHONDRITE; SOLAR-SYSTEM; METEORITES; ORIGIN; ACCRETION; DUST; FRACTIONATION Multiple languages Geochemistry & Geophysics Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/16409