Constraints on 87Sr/86Sr of Late Ediacaran seawater: insight from Siberian high-Sr limestones

Melezhik, V.A., Pokrovsky, B.G., Fallick, A.E., Kuznetsov, A.B. and Bujakaite, M.I. (2009) Constraints on 87Sr/86Sr of Late Ediacaran seawater: insight from Siberian high-Sr limestones. Journal of the Geological Society, 166(1), pp. 183-191. (doi: 10.1144/0016-76492007-171)

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Publisher's URL: http://dx.doi.org/10.1144/0016-76492007-171

Abstract

In SE Siberia, carbonate formations with δ13Ccarb values ranging between –12‰ and –7‰ (V-PDB) and Sr concentrations of up to 2.5% occupy an area of 40 000 km2. Several successions exceed 1000 m in thickness and represent the world's largest known exposures of sedimentary carbonates exhibiting extreme depletion in 13C. The carbonates were deposited on a carbonate platform evolving from a mixed carbonate–siliciclastic ramp to a carbonate ramp, and then from a peritidal rimmed shelf to a deep-water open shelf. All sequences reveal a facies-independent, upward rise in marine δ13Ccarb from –12‰ to –7‰. The trend and magnitude of the values mimic those that are characteristic of the 600–550 Ma Shuram–Wonoka isotope event. A coincident stratigraphic rise in 87Sr/86Sr from 0.70802 to 0.70862 in several sections of limestones, containing 4400 µg g–1 Sr on average, is considered to be by far the best available constraint on a temporal variation of seawater isotopic composition through the Late Ediacaran. If the greatest temporal rate of change in seawater 87Sr/86Sr observed in the Cenozoic is applied to the Siberian sections, the calculated minimum duration for the Suram–Wonoka event is 10 Ma.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Fallick, Professor Anthony
Authors: Melezhik, V.A., Pokrovsky, B.G., Fallick, A.E., Kuznetsov, A.B., and Bujakaite, M.I.
Subjects:Q Science > QE Geology
G Geography. Anthropology. Recreation > GE Environmental Sciences
College/School:College of Science and Engineering > Scottish Universities Environmental Research Centre
Journal Name:Journal of the Geological Society
ISSN:0016-7649

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