title: Protracted core formation and rapid accretion of protoplanets.
abstract: Understanding core formation in meteorite parent bodies is critical for constraining the fundamental processes of protoplanet accretion and differentiation within the solar protoplanetary disk. We report variations of 5 to 20 parts per million in (182)W, resulting from the decay of now-extinct (182)Hf, among five magmatic iron meteorite groups. These (182)W variations indicate that core formation occurred over an interval of ~1 million years and may have involved an early segregation of Fe-FeS and a later segregation of Fe melts. Despite this protracted interval of core formation, the iron meteorite parent bodies probably accreted concurrently ~0.1 to 0.3 million years after the formation of Ca-Al-rich inclusions. Variations in volatile contents among these bodies, therefore, did not result from accretion at different times from an incompletely condensed solar nebula but must reflect local processes within the nebula.
authors.affiliation: Institut für Planetologie, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Strasse 10, DE-48149 Münster, Germany. ETH Zürich, Inst. of Geochemistry and Petrology, Clausiusstrasse 25, CH-8092 Zürich, Switzerland.
authors.forename: T S
authors.initials: TS
authors.lastname: Kruijer
authors.affiliation: Department of Geology, University of Maryland, College Park, MD 20742, USA.
authors.forename: M
authors.initials: M
authors.lastname: Touboul
authors.affiliation: Institut für Planetologie, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Strasse 10, DE-48149 Münster, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Fischer-Gödde
authors.affiliation: Department of Geology, University of Maryland, College Park, MD 20742, USA.
authors.forename: K R
authors.initials: KR
authors.lastname: Bermingham
authors.affiliation: Department of Geology, University of Maryland, College Park, MD 20742, USA.
authors.forename: R J
authors.initials: RJ
authors.lastname: Walker
authors.affiliation: Institut für Planetologie, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Strasse 10, DE-48149 Münster, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Kleine