Links of organic carbon cycling and burial to depositional depth gradients and establishment of a snowball Earth at 2.3Ga. Evidence from the Timeball Hill Formation,Transvaal Supergroup, South Africa.

Research Article| June 01, 2006 Links of organic carbon cycling and burial to depositional depth gradients and establishment of a snowball Earth at 2.3Ga. Evidence from the Timeball Hill Formation,Transvaal Supergroup, South Africa. L.L. Coetzee; L.L. Coetzee Paleoproterozoic Mineralization Research Group, Department of Geology, University of Johannesburg, P.O. Box 524, Auckland Park 2006, South Africa e-mail: llc@rau.ac.za; njb@rau.ac.za; jg@rau.ac.za Search for other works by this author on: GSW Google Scholar N.J. Beukes; N.J. Beukes Paleoproterozoic Mineralization Research Group, Department of Geology, University of Johannesburg, P.O. Box 524, Auckland Park 2006, South Africa e-mail: llc@rau.ac.za; njb@rau.ac.za; jg@rau.ac.za Search for other works by this author on: GSW Google Scholar J. Gutzmer; J. Gutzmer Paleoproterozoic Mineralization Research Group, Department of Geology, University of Johannesburg, P.O. Box 524, Auckland Park 2006, South Africa e-mail: llc@rau.ac.za; njb@rau.ac.za; jg@rau.ac.za Search for other works by this author on: GSW Google Scholar T. Kakegawa T. Kakegawa Graduate School of Science, Tohoku University, Aramaki Aza Aoba, Sendai City, Japan, 980-8570 e-mail: kakegawa@mail.tains.tohoku.ac.jp Search for other works by this author on: GSW Google Scholar Author and Article Information L.L. Coetzee Paleoproterozoic Mineralization Research Group, Department of Geology, University of Johannesburg, P.O. Box 524, Auckland Park 2006, South Africa e-mail: llc@rau.ac.za; njb@rau.ac.za; jg@rau.ac.za N.J. Beukes Paleoproterozoic Mineralization Research Group, Department of Geology, University of Johannesburg, P.O. Box 524, Auckland Park 2006, South Africa e-mail: llc@rau.ac.za; njb@rau.ac.za; jg@rau.ac.za J. Gutzmer Paleoproterozoic Mineralization Research Group, Department of Geology, University of Johannesburg, P.O. Box 524, Auckland Park 2006, South Africa e-mail: llc@rau.ac.za; njb@rau.ac.za; jg@rau.ac.za T. Kakegawa Graduate School of Science, Tohoku University, Aramaki Aza Aoba, Sendai City, Japan, 980-8570 e-mail: kakegawa@mail.tains.tohoku.ac.jp Publisher: Geological Society of South Africa First Online: 09 Mar 2017 Online ISSN: 1996-8590 Print ISSN: 1012-0750 © 2006 Geological Society of South Africa South African Journal of Geology (2006) 109 (1-2): 109–122. https://doi.org/10.2113/gssajg.109.1-2.109 Article history First Online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation L.L. Coetzee, N.J. Beukes, J. Gutzmer, T. Kakegawa; Links of organic carbon cycling and burial to depositional depth gradients and establishment of a snowball Earth at 2.3Ga. Evidence from the Timeball Hill Formation,Transvaal Supergroup, South Africa.. South African Journal of Geology 2006;; 109 (1-2): 109–122. doi: https://doi.org/10.2113/gssajg.109.1-2.109 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietySouth African Journal of Geology Search Advanced Search Abstract Closely spaced samples of carbonaceous shales and siltstones from two upwards coarsening deltaic parasequences of the early Paleoproterozoic Timeball Hill Formation of the Pretoria Group, Transvaal Supergroup were analysed for their organic carbon content and isotopic composition. We illustrate that trends in the organic carbon isotopic signature are closely linked to changes in the depositional environment and also to variations in climate. Systematic trends displayed by organic carbon isotope values suggest that a biosynthetic chain transporting organic carbon from the oxygen-rich surface water to anoxic deep water was already present in the early Paleoproterozoic Ocean. Just as in modern deltaic environments, aerobic degradation of organic matter occurred in the shallow water and recycling of organic matter in the deeper water led to the preservation of isotopically light organic carbon. Sampling in a sequence stratigraphic framework also reveals that over time, the preserved organic matter became more13C enriched. This trend may be linked to a global decrease in atmospheric CO2 which eventually led to a major ice-age that is recorded by glacial diamictite capping the Timeball Hill Formation. The results confirm that in order to reach a better understanding of organic carbon cycling in the Precambrian, sedimentary facies, depositional environment and post-depositional modifications of carbon isotopic values must be taken into account. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.