Universität zu Köln

Peters, Stefan T. M., Muenker, Carsten, Pfeifer, Markus ORCID: 0000-0002-2335-8860, Elfers, Bo-Magnus ORCID: 0000-0003-0548-772X and Sprung, Peter ORCID: 0000-0003-4862-1415 (2017). Distribution of p-process Hf-174 in early solar system materials and the origin of nucleosynthetic Hf and W isotope anomalies in Ca-Al rich inclusions. Earth Planet. Sci. Lett., 459. S. 70 - 80. AMSTERDAM: ELSEVIER. ISSN 1385-013X

Full text not available from this repository.

Abstract

Some nuclides that were produced in supernovae are heterogeneously distributed between different meteoritic materials. In some cases these heterogeneities have been interpreted as the result of interaction between ejecta from a nearby supernova and the nascent solar system. Particularly in the case of the oldest objects that formed in the solar system - Ca-Al rich inclusions (CAls) - this view is confirm the hypothesis that a nearby supernova event facilitated or even triggered solar system formation. We present Hf isotope data for bulk meteorites, terrestrial materials and CAIs, for the first time including the low-abundance isotope Hf-174 (similar to 0.16%). This rare isotope was likely produced during explosive 0/Ne shell burning in massive stars (i.e., the classical p-process), and therefore its abundance potentially provides a sensitive tracer for putative heterogeneities within the solar system that were introduced by supernova ejecta. For CAls and one LL chondrite, also complementary W isotope data are reported for the same sample cuts. Once corrected for small neutron capture effects, different chondrite groups, eucrites, a silicate inclusion of a JAB iron meteorite, and terrestrial materials display homogeneous Hf isotope compositions including 174Hf. Hafnium-174 was thus uniformly distributed in the inner solar system when planetesimals formed at the <50 ppm level. This finding is in good agreement with the evidently homogeneous distributions of p-process isotopes W-180, Os-184 and possibly Pt-180 between different iron meteorite groups. In contrast to bulk meteorite samples, CAls show variable depletions in p-process 174Hf with respect to the inner solar system composition, and also variable r-process (or s-process) Hf and W contributions. Based on combined Hf and W isotope compositions, we show that CAls sampled at least one component in which the proportion of r- and s-process derived Hf and W deviates from that of supernova ejecta. The Hf and W isotope anomalies in CAls are therefore best explained by selective processing of presolar carrier phases prior to CAI formation, and not by a late injection of supernova materials. Likewise, other isotope anomalies in additional elements in CAIs relative to the bulk solar system may reflect the same process. The isotopic heterogeneities between the first refractory condensates may have been eradicated partially during CAI formation, because W isotope anomalies in CAls appear to decrease with increasing W concentrations as inferred from time -integrated (182)w/W-184. Importantly, the Lu-178-Hf-176 and Hf-182-W-182 chronometers are not significantly affected by nucleosynthetic heterogeneity of Hf isotopes in bulk meteorites, but may be affected in CAls. (C) 2016 Elsevier B.V. All rights reserved.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Peters, Stefan T. M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Muenker, Carsten UNSPECIFIED UNSPECIFIED UNSPECIFIED Pfeifer, Markus UNSPECIFIED orcid.org/0000-0002-2335-8860 UNSPECIFIED Elfers, Bo-Magnus UNSPECIFIED orcid.org/0000-0003-0548-772X UNSPECIFIED Sprung, Peter UNSPECIFIED orcid.org/0000-0003-4862-1415 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-241245
DOI:	10.1016/j.epsl.2016.11.009
Journal or Publication Title:	Earth Planet. Sci. Lett.
Volume:	459
Page Range:	S. 70 - 80
Date:	2017
Publisher:	ELSEVIER
Place of Publication:	AMSTERDAM
ISSN:	1385-013X
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language CORE FORMATION; NEUTRON-CAPTURE; LU-HF; CROSS-SECTIONS; STELLAR ORIGIN; METEORITES; HETEROGENEITY; CHONDRITES; NEBULA; ALLENDE Multiple languages Geochemistry & Geophysics Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/24124