Universität zu Köln

Shah, Jay ORCID: 0000-0001-8660-4814, Bates, Helena C., Muxworthy, Adrian R., Hezel, Dominik C., Russell, Sara S. and Genge, Matthew J. (2017). Long-lived magnetism on chondrite parent bodies. Earth Planet. Sci. Lett., 475. S. 106 - 119. AMSTERDAM: ELSEVIER SCIENCE BV. ISSN 1385-013X

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Abstract

We present evidence for both early- and late-stage magnetic activity on the CV and LOLL parent bodies respectively from chondrules in Vigarano and Bjurbole. Using micro-CT scans to re-orientate chondrules to their in-situ positions, we present a new micron-scale protocol for the paleomagnetic conglomerate test. The paleomagnetic conglomerate test determines at 95% confidence, whether clasts within a conglomerate were magnetized before or after agglomeration, i.e., for a chondritic meteorite whether the chondrules carry a pre- or post-accretionary remanent magnetization. We found both meteorites passed the conglomerate test, i.e., the chondrules had randomly orientated magnetizations. Vigarano's heterogeneous magnetization is likely of shock origin, due to the 10 to 20 GPa impacts that brecciated its precursor material on the parent body and transported it to re-accrete as the Vigarano breccia. The magnetization was likely acquired during the break-up of the original body, indicating a CV parent body dynamo was active similar to 9 Ma after Solar System formation. Bjurbole's magnetization is due to tetrataenite, which transformed from taenite as the parent body cooled to below 320 degrees C, when an ambient magnetic field imparted a remanence. We argue either the high intrinsic anisotropy of tetrataenite or brecciation on the parent body manifests as a randomly orientated distribution, and a L/LL parent body dynamo must have been active at least 80 to 140 Ma after peak metamorphism. Primitive chondrites did not originate from entirely primitive, never molten and/or differentiated parent bodies. Primitive chondrite parent bodies consisted of a differentiated interior sustaining a long-lived magnetic dynamo, encrusted by a layer of incrementally accreted primitive meteoritic material. The different ages of carbonaceous and ordinary chondrite parent bodies might indicate a general difference between carbonaceous and ordinary chondrite parent bodies, and/or formation location in the protoplanetary disk. (C) 2017 The Authors. Published by Elsevier B.V.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Shah, Jay UNSPECIFIED orcid.org/0000-0001-8660-4814 UNSPECIFIED Bates, Helena C. UNSPECIFIED UNSPECIFIED UNSPECIFIED Muxworthy, Adrian R. UNSPECIFIED UNSPECIFIED UNSPECIFIED Hezel, Dominik C. UNSPECIFIED UNSPECIFIED UNSPECIFIED Russell, Sara S. UNSPECIFIED UNSPECIFIED UNSPECIFIED Genge, Matthew J. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-216197
DOI:	10.1016/j.epsl.2017.07.035
Journal or Publication Title:	Earth Planet. Sci. Lett.
Volume:	475
Page Range:	S. 106 - 119
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 SOLAR NEBULA; CARBONACEOUS CHONDRITE; REMANENT MAGNETIZATION; HYSTERESIS PROPERTIES; SHOCK MAGNETIZATION; IRON PARTICLES; PALEOMAGNETISM; CHONDRULES; DYNAMO; METAL Multiple languages Geochemistry & Geophysics Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/21619