Universität zu Köln

Pringle, Emily A., Moynier, Frederic, Beck, Pierre, Paniello, Randal and Hezel, Dominik C. (2017). The origin of volatile element depletion in early solar system material: Clues from Zn isotopes in chondrules. Earth Planet. Sci. Lett., 468. S. 62 - 72. AMSTERDAM: ELSEVIER SCIENCE BV. ISSN 1385-013X

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Abstract

Volatile lithophile elements are depleted in the different planetary materials to various degrees, but the origin of these depletions is still debated. Stable isotopes of moderately volatile elements such as Zn can be used to understand the origin of volatile element depletions. Samples with significant volatile element depletions, including the Moon and terrestrial tektites, display heavy Zn isotope compositions (i.e. enrichment of Zn-66 vs. Zn-64), consistent with kinetic Zn isotope fractionation during evaporation. However, Luck et al. (2005) found a negative correlation between delta Zn-66 and 1/[Zn] between CI, CM, CO, and CV chondrites, opposite to what would be expected if evaporation caused the Zn abundance variations among chondrite groups. We have analyzed the Zn isotope composition of multiple samples of the major carbonaceous chondrite classes: CI (1), CM (4), CV (2), CO (4), CB (2), CH (2), CK (4), and CK/CR (1). The bulk chondrites define a negative correlation in a plot of delta Zn-66 vs 1/[Zn], confirming earlier results that Zn abundance variations among carbonaceous chondrites cannot be explained by evaporation. Exceptions are CB and CH chondrites, which display Zn systematics consistent with a collisional formation mechanism that created enrichment in heavy Zn isotopes relative to the trend defined by CI-CK. We further report Zn isotope analyses of chondrite components, including chondrules from Allende (CV3) and Mokoia (CV3), as well as an aliquot of Allende matrix. All chondrules are enriched in light Zn isotopes (similar to 500 ppm on Zn-66/Zn-64) relative to the bulk, contrary to what would be expected if Zn were depleted during evaporation, on the other hand the matrix has a complementary heavy isotope composition. We report sequential leaching experiments in un-equilibrated ordinary chondrites, which show sulfides are isotopically heavy compared to silicates and the bulk meteorite by ca. +0.65 per mil on Zn-66/Zn-64. We suggest isotopically heavy sulfides were removed from either chondrules or their precursors, thereby producing the light Zn isotope enrichments in chondrules. (C) 2017 The Author(s). Published by Elsevier B.V.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Pringle, Emily A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Moynier, Frederic UNSPECIFIED UNSPECIFIED UNSPECIFIED Beck, Pierre UNSPECIFIED UNSPECIFIED UNSPECIFIED Paniello, Randal UNSPECIFIED UNSPECIFIED UNSPECIFIED Hezel, Dominik C. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-227663
DOI:	10.1016/j.epsl.2017.04.002
Journal or Publication Title:	Earth Planet. Sci. Lett.
Volume:	468
Page Range:	S. 62 - 72
Date:	2017
Publisher:	ELSEVIER SCIENCE BV
Place of Publication:	AMSTERDAM
ISSN:	1385-013X
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language NEBULA RESERVOIRS; FRACTIONATION; CHONDRITES; ZINC; CONSTRAINTS; METAL; GEOCHEMISTRY; TIMESCALES; METEORITES; IMPACT Multiple languages Geochemistry & Geophysics Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/22766