Universität zu Köln

Koefoed, Piers ORCID: 0000-0002-4036-6088, Pravdivtseva, Olga, Chen, Heng, Gerritzen, Carina, Thiemens, Maxwell M. and Wang, Kun (2020). Potassium isotope systematics of the LL4 chondrite Hamlet: Implications for chondrule formation and alteration. Meteorit. Planet. Sci., 55 (8). S. 1833 - 1848. HOBOKEN: WILEY. ISSN 1945-5100

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Abstract

Here, we apply recently developed high-precision K isotope analyses to individual components of the LL4 chondrite Hamlet in order to investigate key processes which occurred during chondrite formation. The K isotopic compositions of all Hamlet chondrules range from -1.36 parts per thousand to -0.24 parts per thousand delta K-41 while the matrix and bulk samples show ranges of -0.89 parts per thousand to -0.80 parts per thousand and -0.86 parts per thousand to -1.08 parts per thousand delta K-41, respectively. This range of delta K-41 values is significantly less than what was seen by in situ K isotopic analysis of Semarkona and Bishunpur chondrules, a likely effect of the different chondrite petrologic types, analytical artifacts in the SIMS analyses, and chondrule rim effects. Strong evidence for secondary parent-body alteration effects within Hamlet suggests its K fractionation and distribution are dominantly controlled by these processes. Interestingly, the strong correlation between delta K-41 and chondrule mass suggests that chondrule size played a significant role in the K isotopic distribution within Hamlet. This trend is likely a result of either inherited initial differences in the chondrule K isotopic ratios which were not completely overprinted or mechanisms involved in the metamorphism processes creating variations. This K isotope correlation with chondrule mass could also be suggestive of chondrule-forming nebular processes; nevertheless, it is currently unable to definitively favor any specific model. The K isotopic similarities between Hamlet and bulk ordinary chondrites suggest that all LL chondrites, if not all ordinary chondrites, may have formed via the same processes. Nevertheless, analysis of more pristine chondrules from chondrites of lower metamorphic grade is required to further assess any nebular processes of chondrule formation.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Koefoed, Piers UNSPECIFIED orcid.org/0000-0002-4036-6088 UNSPECIFIED Pravdivtseva, Olga UNSPECIFIED UNSPECIFIED UNSPECIFIED Chen, Heng UNSPECIFIED UNSPECIFIED UNSPECIFIED Gerritzen, Carina UNSPECIFIED UNSPECIFIED UNSPECIFIED Thiemens, Maxwell M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Wang, Kun UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-325688
DOI:	10.1111/maps.13545
Journal or Publication Title:	Meteorit. Planet. Sci.
Volume:	55
Number:	8
Page Range:	S. 1833 - 1848
Date:	2020
Publisher:	WILEY
Place of Publication:	HOBOKEN
ISSN:	1945-5100
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language MC-ICP-MS; ORIGIN; FRACTIONATION; EARTH; TEMPERATURES; CONSTRAINTS; SEMARKONA; ANOMALIES; ASTEROIDS; DEPLETION Multiple languages Geochemistry & Geophysics Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/32568