Universität zu Köln

Montinaro, Alice, Strauss, Harald, Mason, Paul R. D., Roerdink, Desiree ORCID: 0000-0002-1182-3606, Muenker, Carsten, Schwarz-Schampera, Ulrich, Arndt, Nicholas T., Farquhar, James, Beukes, Nicolas J., Gutzmer, Jens and Peters, Marc (2015). Paleoarchean sulfur cycling: Multiple sulfur isotope constraints from the Barberton Greenstone Belt, South Africa. Precambrian Res., 267. S. 311 - 323. AMSTERDAM: ELSEVIER SCIENCE BV. ISSN 1872-7433

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Abstract

Mass-dependent and mass-independent sulfur isotope fractionation archived in volcanic and sedimentary rocks from the Barberton Greenstone Belt (3550-3215 Ma), South Africa, provide constraints for sulfur cycling on the early Earth. Four different sample suites were studied: komatiites and tholeiites, barite, massive and disseminated sulfide ores, and non-mineralized black shales. Variable but generally slightly positive 8348 values between -0.7 and +5.2 parts per thousand, negative Delta S-33 values between -0.50 and -0.09 parts per thousand, and a negative correlation between delta S-34 and Delta S-33 as well as between Delta S-33 and Delta S-36 for komatiites and tholeiites from the Komati Formation and from the Weltevreden Formation are outside the expected range of unfractionated juvenile sulfur. Instead, results suggest alteration of oceanic crustal rock sulfur through interactions with fluids that most likely derived their sulfur from seawater. Barite from the Mapepe Formation displays positive delta S-34 values between +3.1 and +8.1 parts per thousand and negative Delta S-33 values between -0.77 and -0.34 parts per thousand. The mass-independent sulfur isotope fractionation indicates an atmospheric sulfur source, notably photolytic sulfate, whereas the positive delta S-34 values suggest bacterial sulfate reduction of the marine sulfate reservoir. Non-mineralized black shale samples from the presumed stratigraphic equivalent of the Mapepe Formation show positive delta S-34 values between 0.0 and +1.3 parts per thousand and positive Delta S-33 values between +0.59 and +2.45 parts per thousand. These results are interpreted to result from the reduction of photolytic elemental sulfur, carrying a positive Delta S-33 signature. Positive delta S-34 values ranging from +0.7 to +3.5 parts per thousand and slightly negative Delta S-33 values between -0.17 and -0.12 parts per thousand characterize massive and disseminated sulfides from the Bien Venue Prospect. Results suggest unfractionated juvenile magmatic sulfur source as the primary sulfur source, but a contribution from recycled seawater sulfate, which would be indicative of submarine hydrothermal activity, cannot be ruled out. Massive and disseminated sulfides from the M'hlati prospect are distinctly different from massive and disseminated sulfide from the Bien Venue Prospect. They show negative delta S-34 values between -1.2 and -0.1 parts per thousand and positive Delta S-33 values between +2.66 and +3.17 parts per thousand thus, displaying a sizeable mass-independent sulfur isotopic fractionation. Again, these samples clearly exhibit the incorporation of an atmospheric MIF-S signal. The source of sulfur for these samples has positive Delta S-33 values, suggesting a connection with photolytic elemental sulfur. In conclusion, the sulfur isotope signatures in Paleoarchean rocks from the Barberton Greenstone Belt are diverse and indicate the incorporation of different sources of sulfur. For komatiites and tholeiites, barite and massive and possibly also disseminated sulfides from Bien Venue, multiple sulfur isotopes are related to ambient seawater sulfate and its photolytic origin, while massive and disseminated sulfides from M'hlati and non-mineralized black shales are related to a second (photolytic elemental sulfur) end member. (C) 2015 Elsevier B.V. All rights reserved.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Montinaro, Alice UNSPECIFIED UNSPECIFIED UNSPECIFIED Strauss, Harald UNSPECIFIED UNSPECIFIED UNSPECIFIED Mason, Paul R. D. UNSPECIFIED UNSPECIFIED UNSPECIFIED Roerdink, Desiree UNSPECIFIED orcid.org/0000-0002-1182-3606 UNSPECIFIED Muenker, Carsten UNSPECIFIED UNSPECIFIED UNSPECIFIED Schwarz-Schampera, Ulrich UNSPECIFIED UNSPECIFIED UNSPECIFIED Arndt, Nicholas T. UNSPECIFIED UNSPECIFIED UNSPECIFIED Farquhar, James UNSPECIFIED UNSPECIFIED UNSPECIFIED Beukes, Nicolas J. UNSPECIFIED UNSPECIFIED UNSPECIFIED Gutzmer, Jens UNSPECIFIED UNSPECIFIED UNSPECIFIED Peters, Marc UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-394867
DOI:	10.1016/j.precamres.2015.06.008
Journal or Publication Title:	Precambrian Res.
Volume:	267
Page Range:	S. 311 - 323
Date:	2015
Publisher:	ELSEVIER SCIENCE BV
Place of Publication:	AMSTERDAM
ISSN:	1872-7433
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language Geosciences, Multidisciplinary Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/39486