Palaeoproterozoic evaporites in Fennoscandia: implications for seawater sulphate, the rise of atmospheric oxygen and local amplification of the delta C-13 excursion

Melezhik, V.A., Fallick, A.E., Rychanchik, D.V. and Kuznetsov, A.B. (2005) Palaeoproterozoic evaporites in Fennoscandia: implications for seawater sulphate, the rise of atmospheric oxygen and local amplification of the delta C-13 excursion. Terra Nova, 17(2), pp. 141-148. (doi: 10.1111/j.1365-3121.2005.00600.x)

Abstract

This paper addresses global oxygenation and establishment of a marine sulphate reservoir in the Palaeoproterozoic. We report syn-depositional, marine, anhydrite-containing pseudomorphs after Ca-sulphates as widespread throughout the Tulomozero Formation in the SE Fennoscandian Shield, implying that surface waters were oxidized and a large SO42- marine reservoir was developed as early as 2100 Ma. The Ca-sulphates and associated magnesite and halite precipitated syn-depositionally from oxidized, evolved and modified seawater in coastal playa, sabkha and intertidal flat settings. Sr-87/Sr-86 and delta(13)C of associated C-13-rich stromatolitic dolostones were environmentally controlled with the highest ratios occurring in playa and sabkha carbonates. The results imply that the Palaeoproterozoic delta(13)C(carb) excursion was amplified by 8% by local environmental factors and calls into question many observations of putative delta(13)C global signals reported previously from similar Palaeoproterozoic, evaporitic, dolostones. The local environmental amplification can explain a large regional and intercontinental delta(13)C discrepancy observed in synchronous carbonates.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Fallick, Professor Anthony
• Authors: Melezhik, V.A., Fallick, A.E., Rychanchik, D.V., and Kuznetsov, A.B.
• Subjects: Q Science > QE Geology
• College/School: College of Science and Engineering > Scottish Universities Environmental Research Centre
• Journal Name: Terra Nova
• Publisher: Wiley-Blackwell Publishing Ltd.
• ISSN: 0954-4879
• ISSN (Online): 1365-3121