Universität zu Köln

Fischer-Goedde, Mario, Elfers, Bo-Magnus ORCID: 0000-0003-0548-772X, Muenker, Carsten, Szilas, Kristoffer ORCID: 0000-0002-5541-306X, Maier, Wolfgang D., Messling, Nils, Morishita, Tomoaki, Van Kranendonk, Martin and Smithies, Hugh (2020). Ruthenium isotope vestige of Earth's pre-late-veneer mantle preserved in Archaean rocks. Nature, 579 (7798). S. 240 - 256. BERLIN: NATURE RESEARCH. ISSN 1476-4687

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Abstract

The accretion of volatile-rich material from the outer Solar System represents a crucial prerequisite for Earth to develop oceans and become a habitable planet(1-4). However, the timing of this accretion remains controversial(5-8). It has been proposed that volatile elements were added to Earth by the late accretion of a late veneer consisting of carbonaceous-chondrite-like material after core formation had ceased(6,9,10). This view could not be reconciled with the ruthenium (Ru) isotope composition of carbonaceous chondrites(5,11), which is distinct from that of the modern mantle(12), or of any known meteorite group(5). As a possible solution, Earth's pre-late-veneer mantle could already have contained a fraction of Ru that was not fully extracted by core formation(13). The presence of such pre-late-veneer Ru can only be established if its isotope composition is distinct from that of the modern mantle. Here we report the first high-precision, mass-independent Ru isotope compositions for Eoarchaean ultramafic rocks from southwest Greenland, which display a relative Ru-100 excess of 22 parts per million compared with the modern mantle value. This Ru-100 excess indicates that the source of the Eoarchaean rocks already contained a substantial fraction of Ru before the accretion of the late veneer. By 3.7 billion years ago, the mantle beneath southwest Greenland had not yet fully equilibrated with late accreted material. Otherwise, no Ru isotopic difference relative to the modern mantle would be observed. If constraints from other highly siderophile elements besides Ru are also considered(14), the composition of the modern mantle can only be reconciled if the late veneer contained substantial amounts of carbonaceous-chondrite-like materials with their characteristic Ru-100 deficits. These data therefore relax previous constraints on the late veneer and are consistent with volatile-rich material from the outer Solar System being delivered to Earth during late accretion.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Fischer-Goedde, Mario UNSPECIFIED UNSPECIFIED UNSPECIFIED Elfers, Bo-Magnus UNSPECIFIED orcid.org/0000-0003-0548-772X UNSPECIFIED Muenker, Carsten UNSPECIFIED UNSPECIFIED UNSPECIFIED Szilas, Kristoffer UNSPECIFIED orcid.org/0000-0002-5541-306X UNSPECIFIED Maier, Wolfgang D. UNSPECIFIED UNSPECIFIED UNSPECIFIED Messling, Nils UNSPECIFIED UNSPECIFIED UNSPECIFIED Morishita, Tomoaki UNSPECIFIED UNSPECIFIED UNSPECIFIED Van Kranendonk, Martin UNSPECIFIED UNSPECIFIED UNSPECIFIED Smithies, Hugh UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-342946
DOI:	10.1038/s41586-020-2069-3
Journal or Publication Title:	Nature
Volume:	579
Number:	7798
Page Range:	S. 240 - 256
Date:	2020
Publisher:	NATURE RESEARCH
Place of Publication:	BERLIN
ISSN:	1476-4687
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language HIGHLY SIDEROPHILE ELEMENT; SOUTHERN WEST GREENLAND; ISUA SUPRACRUSTAL BELT; PLATINUM-GROUP; ULTRAMAFIC ROCKS; BUSHVELD COMPLEX; W-182 EVIDENCE; 3.8 GA; SILICATE; DIFFERENTIATION Multiple languages Multidisciplinary Sciences Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/34294