Coastal sabkha dolomites and calcitised sulphates preserving the Lomagundi-Jatuli carbon isotope signal

Brasier, A.T., Fallick, A.E., Prave, A.R., Melezhik, V.A. and Lepland, A. (2011) Coastal sabkha dolomites and calcitised sulphates preserving the Lomagundi-Jatuli carbon isotope signal. Precambrian Research, 189(1-2), pp. 193-211. (doi: 10.1016/j.precamres.2011.05.011)

Full text not currently available from Enlighten.

Publisher's URL:


Palaeoproterozoic Tulomozero Formation carbonates of the Onega basin were targeted by ICDP FAR-DEEP Hole 10B. The recovered rocks contain abundant evidence for Palaeoproterozoic gypsum and anhydrite, particularly in the form of pseudomorphs of inclusion-containing nodules, swallow-tail twinned crystals and evaporite dissolution breccias. Similarly, sand-patch fabric indicates the former presence of surface-covering salt crusts in the Palaeoproterozoic. Atmospheric oxygen and seawater sulphate levels at that time must have been sufficient to allow such sulphates to form. Carbonate δ<sup>13</sup>C values are considered sedimentary or early diagenetic, predating greenschist facies metamorphism associated with the Svecofennian Orogeny. These carbonate δ<sup>13</sup>C values range from +7.7 to +15.7‰, with the highest (and lowest) values found in dolostones. The dolostones as well as calcitised calcium sulphates record the Lomagundi-Jatuli signal. However evidence for activity of sulphate-reducing and/or methanogenic bacteria seems to be lacking. Dolomite precipitation (or dolomitisation), calcium sulphate calcitisation and production of the high <sup>13</sup>C values (processes which typically involve such bacteria in the Phanerozoic) are thus inferred to have proceeded without the direct influence of sulphate reducers and methanogens. The most plausible explanation for the Lomagundi-Jatuli excursion seems to remain significant sequestration of organic carbon in a location yet to be identified.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Brasier, Dr Alexander and Fallick, Professor Anthony
Authors: Brasier, A.T., Fallick, A.E., Prave, A.R., Melezhik, V.A., and Lepland, A.
College/School:College of Science and Engineering > Scottish Universities Environmental Research Centre
Journal Name:Precambrian Research
Published Online:16 June 2011

University Staff: Request a correction | Enlighten Editors: Update this record