Universität zu Köln

Schulz, Toni, Viehmann, Sebastian ORCID: 0000-0001-6138-5862, Hezel, Dominik C., Koeberl, Christian and Bau, Michael (2021). Highly Siderophile Elements and Coupled Fe-Os Isotope Signatures in the Temagami Iron Formation, Canada: Possible Signatures of Neoarchean Seawater Chemistry and Earth's Oxygenation History. Astrobiology, 21 (8). S. 924 - 940. NEW ROCHELLE: MARY ANN LIEBERT, INC. ISSN 1557-8070

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Abstract

Banded iron formations (BIFs) were deposited before and concurrent with the Great Oxidation Event at similar to 2.33 Ga. They provide useful archives that document the transformation of the Precambrian hydrosphere from anoxic to progressively oxygenated conditions. Their formation involves removal of oceanic Fe by either inorganic or biologically promoted Fe2+ oxidation, or both. To evaluate depositional settings, elemental sources that affect seawater chemistry, and oxidation pathways, we present the first combined highly siderophile element (HSE) and Fe-Os isotope study for the similar to 2.7 Ga Temagami BIF, Abitibi Greenstone Belt, Ontario (Canada). HSE abundances and Os-187/Os-188 ratios show no systematic variation between alternating magnetite and (meta)chert bands of the Temagami BIF. Whereas HSE concentrations mostly resemble modern crustal values, present-day Os-187/Os-188 ratios range from similar to 0.17 to similar to 10.8. Magnetite samples define a regression line corresponding to an age of 2661 +/- 126 Ma. A chondrite-like Os-187/Os-188 initial value is in agreement with earlier studies on Neoarchean marine sediments and is thought to reflect seawater composition, which, unlike modern oceans, is dominated by mantle-like Os-187 inventory most likely derived from deep-sea hydrothermal vents. Our delta Fe-56 data vary from about +0.6 parts per thousand to +0.9 parts per thousand and define a sawtooth-like pattern between alternating magnetite and (meta)chert layers. Partial oxidation of hydrothermally sourced Fe(II) and a lack of microbially mediated dissimilatory iron reduction provide the most plausible explanation for the positive delta Fe-56 values. Notably, our delta Fe-56 data for Temagami are in accord with trends defined by literature results for other Algoma-type BIFs that were deposited throughout the Archean.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Schulz, Toni UNSPECIFIED UNSPECIFIED UNSPECIFIED Viehmann, Sebastian UNSPECIFIED orcid.org/0000-0001-6138-5862 UNSPECIFIED Hezel, Dominik C. UNSPECIFIED UNSPECIFIED UNSPECIFIED Koeberl, Christian UNSPECIFIED UNSPECIFIED UNSPECIFIED Bau, Michael UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-580783
DOI:	10.1089/ast.2020.2311
Journal or Publication Title:	Astrobiology
Volume:	21
Number:	8
Page Range:	S. 924 - 940
Date:	2021
Publisher:	MARY ANN LIEBERT, INC
Place of Publication:	NEW ROCHELLE
ISSN:	1557-8070
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language MARINE OS-187/OS-188 RECORD; PLATINUM-GROUP ELEMENTS; ISUA SUPRACRUSTAL BELT; RE-OS; GREENSTONE-BELT; SOUTH-AFRICA; FE(III) REDUCTION; IMPACT SPHERULES; OSMIUM ISOTOPES; HAMERSLEY GROUP Multiple languages Astronomy & Astrophysics; Biology; Geosciences, Multidisciplinary Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/58078