Proterozoic 40Ar/39Ar ages from cave deposits of the Malapa, Sterkfontein and Dinaledi fossil sites, Cradle of Humankind, South Africa

Research Article| March 01, 2017 Proterozoic 40Ar/39Ar ages from cave deposits of the Malapa, Sterkfontein and Dinaledi fossil sites, Cradle of Humankind, South Africa T.V. Makhubela; T.V. Makhubela Department of Geology, University ofjohannesburg, Auckland Park, 2006, South Africa e-mail: tvmakhubela@uj.ac.za; jkramers@uj.ac.za; gabelyanin@uj.ac.za Search for other works by this author on: GSW Google Scholar J.D. Kramers; J.D. Kramers Department of Geology, University ofjohannesburg, Auckland Park, 2006, South Africa e-mail: tvmakhubela@uj.ac.za; jkramers@uj.ac.za; gabelyanin@uj.ac.za Search for other works by this author on: GSW Google Scholar G.A. Belyanin; G.A. Belyanin Department of Geology, University ofjohannesburg, Auckland Park, 2006, South Africa e-mail: tvmakhubela@uj.ac.za; jkramers@uj.ac.za; gabelyanin@uj.ac.za Search for other works by this author on: GSW Google Scholar P.H.G.M. Dirks; P.H.G.M. Dirks College of Science, Technology and Engineering, James Cook University, Townsville, Qld 4811, Australia e-mail: paul.dirks@jcu.edu.au; eric.roberts@jcu.edu.au Search for other works by this author on: GSW Google Scholar E.M. Roberts E.M. Roberts College of Science, Technology and Engineering, James Cook University, Townsville, Qld 4811, Australia e-mail: paul.dirks@jcu.edu.au; eric.roberts@jcu.edu.au Search for other works by this author on: GSW Google Scholar Author and Article Information T.V. Makhubela Department of Geology, University ofjohannesburg, Auckland Park, 2006, South Africa J.D. Kramers Department of Geology, University ofjohannesburg, Auckland Park, 2006, South Africa G.A. Belyanin Department of Geology, University ofjohannesburg, Auckland Park, 2006, South Africa P.H.G.M. Dirks College of Science, Technology and Engineering, James Cook University, Townsville, Qld 4811, Australia E.M. Roberts College of Science, Technology and Engineering, James Cook University, Townsville, Qld 4811, Australia e-mail: tvmakhubela@uj.ac.za; jkramers@uj.ac.za; gabelyanin@uj.ac.za e-mail: paul.dirks@jcu.edu.au; eric.roberts@jcu.edu.au Publisher: Geological Society of South Africa First Online: 10 Apr 2018 Online Issn: 1996-8590 Print Issn: 1012-0750 © 2017 March Geological Society of South AfricaGeological Society of South Africa South African Journal of Geology (2017) 120 (1): 21–44. https://doi.org/10.25131/gssajg.120.1.21 Article history First Online: 10 Apr 2018 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation T.V. Makhubela, J.D. Kramers, G.A. Belyanin, P.H.G.M. Dirks, E.M. Roberts; Proterozoic 40Ar/39Ar ages from cave deposits of the Malapa, Sterkfontein and Dinaledi fossil sites, Cradle of Humankind, South Africa. South African Journal of Geology 2017;; 120 (1): 21–44. doi: https://doi.org/10.25131/gssajg.120.1.21 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 We have explored the use of 40Ar/39Ar dating on Mn ooids and peloids, and fragments of indurated, extremely fine-grained mudstone occurring in cave sediments in the Cradle of Humankind (CoH) UNESCO world heritage site, to obtain ages of fossil-bearing cave sediments. Samples analysed were from the Malapa site (envisaged as a testing ground because it was previously dated with high precision by the uranium-lead method and paleomagnetism), the floor of the Dinaledi Chamber in Rising Star Cave, as well as boreholes 2 and 3 of the Sterkfontein Cave. The 40Ar/39Ar apparent ages of the dated samples turned out to be unrelated to cave formation processes, rendering the Malapa-based validation irrelevant. The results do, however, provide insight into aspects of the origin of the cave sediments and dated material. Most samples yielded disturbed 40Ar/39Ar spectra. The apparent pooled gas ages for the Mn ooids analysed from Malapa range between 476 ± 13 Ma and 1964 ± 13 Ma. Of 5 ooids from Sterkfontein, one yielded 1597 ± 13 Ma, while the rest range between 1960 ± 35 Ma and 2081 ± 13 Ma, the latter being a plateau age. Peloidal Mn nodules from Dinaledi Chamber samples yielded apparent ages between 1975 ± 9 Ma and 2096 ± 13 Ma. Indurated mudstone fragments were analysed from Sterkfontein and for 3 out of 4 samples, the apparent pooled gas ages range from 1970 ± 14 Ma to 2059 ± 13 Ma (one yielded 1623 ± 15 Ma). We conclude that ooids, peloids and indurated mudstone fragments are derived from higher levels in the Transvaal Supergroup stratigraphy, trapped in karst features over time as these were eroded, and finally washed into the caves. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.