U-series dating calcrete as a record of past hydroclimate variation on the west coast of South Africa
Calcrete or pedogenic carbonate is ubiquitous on the landscape in South Africa and is often associated with archaeological sites. Developing the U-series chronometer to date calcretes and understanding how its formation relates to changing hydroclimates is the focus of my current research. Careful fieldwork and a lot of trial and error in the lab are beginning to pay off with some exciting results on their way.
U-Th dating carbonates in the Northern Cape
MSc student Jess von der Meden and I are of the North of Kuruman Project research team. Our role is identifying, describing and dating the enormous and amazing tufa deposits on the landscape around the Ga-Mohana rock shelter. Our goal is to characterise and understand the past changes in hydroclimate that lead to the deposition of the tufas and to link these to the newly discovered MSA deposits in the rock shelter. This feeds into a bigger picture of understanding how early modern humans were living in the arid interior of South Africa.
U-Pb dating early hominin cave sites in South Africa
I have spent the last decade developing the U-Pb chronometer to date the early hominin bearing cave deposits in the 'Cradle of Humankind' outside Johannesburg, South Africa. This work has produced the first set of direct ages for these sites. There is plenty more still to do... We had a big paper come out in Nature in late 2018.
Dating Australopithecus sediba
The site of Malapa, in South Africa, preserves fossils of a new human ancestor, Au. sediba. I was part of the team who dated these fossils to 1.95 million years old. We used U-Pb to date the flowstones and palaeomagnetic analysis of the sediments surrounding the fossils to pin down the age. See Dirks et al., 2010 and Pickering et al., 2011 for more.
Stalagmites as archives of South African palaeoclimate variability
Stalagmites from Sudwala and Cango caves were dated using U-Th and analysed for carbon and oxygen isotopes. We used these proxies to reconstruct the palaeoenvironment at both sites and link this to larger drivers of climate variability. See Green et al., 2015 for more.
Primates of the Caribbean
We dated a piece of carbonate encasing the tibia of fossil primate Antillothrix bernensis recovered from an underwater cave in the Dominican Republic. The age of ~1.2 million years changes our understanding of the palaeobiogeography of this small, island dwelling monkey. See Rosenberger et al., 2015 for more.
The world's oldest sea caves?
The coastal cliffs near the town of Mossel Bay in South Africa preserve an amazing archaeological record. We were surprised to find flowstone and cemented dune remnants as old as 1 million years, which opens up the possibility for more, equally ancient deposits along this coast line. See Pickering et al., 2013 for more.
Jessica von der Meden completed her Honours at the University of Cape Town in 2016. Her project is looking at the micromorphology and stable light isotope signatures of the calcretes from the early hominin occupation sites of Elandsfontein in the Western Cape, South Africa. She is currently doing her Masters on the tufa deposits of the Northern Cape.
Wendy Khumalo completed her Hons in Geology at UCT in 2018 and is currently doing her MSc on investigating inter-decadal records of past hydroclimate variability through climate modeling, seasonality indices and detailed study of annually layered carbonates.
Batande Getyengana graduated with a BSc in Geology and Mathematics in 2018 and is currently busy with Hons in Geology at UCT. He is working on the palaeolake deposits in the Witberg Quarry in the Northern Cape and is characterising the sediments geochemically and investigating the diatom record.
Tara Edwards is PhD student in the Archaeology Program at La Trobe University and her research is focused at Bolt's Farm in the Cradle of Humankind. She is dating the deposits using palaeomag and investigating the micromorphology of the flowstone layers.
Phakama Khuzwayo completed his Hons degree in Geology at UCT in 2018. His project focused on the massive, layered calcrete deposits at Sea Harvest on the west coast of South Africa and understanding their depositional environments.
Rebekah Kurpiel graduated with her PhD from the Archaeology Program at La Trobe University in 2017. Her research focuses on raw material procurement in the Willandra Lakes region in Australia. We used Pb isotopes and trace elements to finger print silcrete outcrops with a view to tracing stone tool sources. Read more about her work here.
Sam Boone is a PhD student at the University of Melbourne working in the Thermochronology and Continental Tectonics group, his thesis is titled 'A low-temperature thermochronology investigation of the Turkana Depression: Implications for the geodynamic evolution of the East African Rift System'. We are experimenting with trying to date East African carbonates with U-series as a side project.
Helen Green graduated from the University of Melbourne in 2013, her thesis titled 'Exploring the palaoeclimate potential of South Eastern Australian speleothems' focused on new stalagmite records from a numbers of caves in Victoria, providing valuable insights into southern hemisphere palaeoclimate dynamics. Helen also worked for me as a Research Assistant while I was on maternity leave, writing up two papers in just 6 months. She is now doing a post doc dating Australian Rock Art with the Kimberly Foundation Australia, read about it here.
Jay Sloman worked on stalagmites from Tasmania for his masters thesis, titled 'Trace elements in speleothems: implications for age models and palaeoclimate'. He is now working as a school teacher - lucky kids!
*=one of my wonderful postgraduate students
Braun, K., Nehme, C., Pickering, R., Rogerson, M., Scroxton, N. 2019. A window into Africa’s past hydroclimates: the SISAL_V1 database contribution, Quaternary, 2, 4, doi:10.3390/quat2010004
Edwards, T.R*., Armstrong, B.J., Birket-Rees, J., Blackwood, A.F., Herries, A.I.R., Penzo-Kajewski, P., Pickering, R., Adams, J.W. 2019. Combining legacy data with new drone and DGPS mapping to identify the provenance of Plio-Pleistocene fossils from Bolt’s Farm, Cradle of Humankind (South Africa), PeerJ, 7, e6202, https://doi.org/10.7717/peerj.6202
Pickering, R., Herries, A., Woodhead, J.D., Hellstrom, J.C., Green, H.E*., Paul, P., Ritzman, T., Strait, D.S., Schoville, B.J., Hancox, J. 2019. South African hominin record restricted to dry phases as demonstrated by U-Pb dated flowstones. Nature, 565, 7738, 226-229, https://doi.org/10.1038/s41586-018-0711-0
Kurpiel, R*., Pickering, R., Maas, R., Stern, N. 2019. Discrete Pb isotope signatures for silcrete sources from the Willandra Lakes region, Australia: a new method for provenancing silcrete artefacts, Journal of Archaeological Science: reports, 23, 62-71, https://doi.org/10.1016/j.jasrep.2018.10.031
Atsawawanunt, K., Comas-Bru, L., Amirnezhad Mozhdehi, S., Deininger, M., Harrison, S.P., Baker, A., Boyd, M., Kausha, N., Masood Ahmed, S., Arienzo, M., Brahim, Y., Bajo, P., Braun, K., Burstyn, Y., Chawchai1, S., Duan, W., Hatvani, I., Hu, J., Kern, Z., Labuhn, I., Lachniet, M., Lechleiter, F.A., Lorrey, A., Pérez-Mejías, C., Pickering, R., Scroxton, N. and SISAL Working Group Members. 2018. The SISAL database: a global resource to document oxygen and carbon isotope records from speleothems. Earth System Science Data, 10(#), 1687-1713
Wurz, S., Bentsen, S., Van Pletzen-Vos, L., Reynard, J. , Brenner M. , Mentzer, S., Pickering, R. Green, H.E*. 2018 Connections, culture and environments 100 000 years ago at Klasies River main site. Quaternary International, 495, 102-115
Herries, AIR., Murszewski, A., Pickering, R., Mallett, T., Joannes-Boyau,R., Armstrong, B., Adams, J., Baker, S., Blackwood, A., Penzo-Kajewski, P., Kappen, P., Leece, A.B., Martin, J., Rovinsky, D., Boschian, G. 2018. Geoarchaeological and 3D visualisation approaches for contextualising in-situ fossil bearing palaeokarst in South Africa: A case study from the ∼2.61 Ma Drimolen Makondo, Quaternary International, 484, 90-110
Pickering, R. 2015. Middle – Lower Pleistocene U-Pb ages for buried speleothems from Wonderwerk Cave, South Africa. African Archaeological Review, 32, 645-668
Rosenberger, A.L., Pickering, R., Green, H., Cooke, S.B., Tallman, M., Morrow, A. Rimoli, R. 2015. 1.3±0.11 Ma ages for underwater remains constrain antiquity and longevity of Dominican primate Antillothrix bernensis, Journal of Human Evolution, 88, 85-96
Hellstrom, J., Pickering, R., 2015. Recent advances and future prospects of the U-Th and U-Pb dating applicable to archaeology, Journal of Archaeological Science, 56, 32-40
Green, H., Pickering, R, Drysdale, R., Johnson, B., Hellstrom, J. 2015. Evidence for global teleconnections in a late Pleistocene speleothem record of water balance and vegetation change at Sudwala Cave, South Africa, Quaternary Science Reviews, 110, 114-130
Braun, D.R., Levin, N.E., Stynder, D., Herries, A.I.R., Archer, W., Forrest, F., Roberts, D.L., Bishop, L.C., Matthews, T., Lehmann, S.B., Pickering, R., Fitzsimmons, K., 2013. Mid-Pleistocene Hominin occupation at Elandsfonein, Western Cape, South Africa, Quaternary Science Reviews, 82, 145-166.
Green, H., Woodhead, J.D., Hellstrom, J., Pickering, R., Drysdale, R., 2013. Re-analysis of key evidence in the case for a hemispherically synchronous response to the Younger Dryas climatic event. Journal of Quaternary Science, 28, 8-12.
Pickering, R., Jacobs, Z., Herries, A.I.R., Karkanas, P., Bar-Matthews, M., Woodhead, J.D., Kappen, P., Fisher, E., Marean, C.W., 2013. Paleoanthropologically Significant South African Sea Caves dated to 1.0 Million Years using a combination of U-Pb, TT-OSL and palaeomagnetism. Quaternary Science Reviews, 65, 39-52.
Woodhead, J.D., Hellstrom, J., Pickering, R., Drysdale, R., Paul, B, Bajo, P. U and Pb variability in older speleothems and strategies for their chronology. 2012. Quaternary Geochronology, 14, 105-113.
Woodhead, J.D., Pickering, R. Beyond 500 ka: progress and prospects in the U-Pb chronology of speleothems, and their application to studies in palaeoclimate, human evolution, biodiversity and tectonics. Chemical Geology, 322–323, 290–299.
Pickering, R., Dirks, P.H.G.M., Jinnah, Z., de Ruiter, D.J., Churchill, S.E., Herrires, A.I.R., Woodhead, J.D., Hellstrom, J.C., Berger, L.R. 2011. Australopithecus sediba at 1.977 Ma and implications for the origins of Genus Homo. Science 333, 1421-1423.
Pickering, R., Kramers, J.D., Hancox, P.J., deRuiter, D.J., Woodhead, J.D., 2011. Contemporary flowstone development links early hominin bearing cave deposits in South Africa. Earth and Planetary Science Letters, 306, 23-32.
Pickering, R. & Kramers, J.D. 2010. A re-appraisal of the stratigraphy and new U-Pb dates at the Sterkfontein hominin site, South Africa. Journal of Human Evolution, 56, 70-86.
Pickering, R., Kramers, J.D., Partridge, T., Kodolanyi, J., Pettke, T. 2010. U–Pb dating of calcite–aragonite layers in speleothems from hominin sites in South Africa by MC-ICP-MS. Quaternary Geochronology, 5 (5), 544-558.
Dirks, P.H.G.M., Kibii, J.M., Kuhn, B.F., Steininger, C., Churchill, S.E., Kramers, J.D., Pickering, R., Farber, D.L., Meriaux, A-S., Herries, A.I.R., King, G.C.P. & Berger, L.R. 2010. Geological setting and age of Australopithecus sediba from Southern Africa. Science, 328, 205-208.
Fleitmann, D., Cheng, H., Badertscher, S., Edwards, R.L., Mudelsee, M., Göktürk, O.M., Fankhauser, A., Pickering, R., Raible, C.C., Matter, A., Kramers, J. & Tüysüz, O. 2009. Timing and climatic impact of Greenland interstadials recorded in stalagmites from northern Turkey. Geophysical Research Letters, 36(19), L19707.
de Ruiter, D.J., Pickering, R., Steininger, C.M., Kramers, J.D., Hancox, P.J., Churchill, S.E. & Berger, L.R. 2009. New Australopithecus robustus fossils and associated U-Pb dates from Cooper’s Cave (Gauteng, South Africa). Journal of Human Evolution, 56, 5, 497-513.
Backwell, L.R., Pickering, R., Brothwell, D., Berger, L.R., Witcomb, M., Martill, D., Penkman, K. & Wilson, A. 2009. Probable human hair found in a fossil hyaena coprolite from Gladysvale cave, South Africa. Journal of Archaeological Science. 36(6): 1269-1276.
Berger, L.R., Pickering, R., Kuhn, B., Backwell, L.R., Hancox, P.J., Kramers, J.D., & Boshoff, P. 2009. A Mid-Pleistocene in situ fossil brown hyaena (Parahyaena brunnea) latrine from Gladysvale Cave, South Africa. Palaeogeography, Palaeoclimatology, Palaeoecology. 279, 3-4, 131-136.
Sutton, M., Pickering, T.R., Pickering, R., Brain., C.K., Clarke, R.J., Heaton, J.L. & Kuman, K. 2009 Newly Discovered Fossil- and Artifact-Bearing Deposits, Uranium-Series Ages and Plio- Pleistocene Hominids at Swartkrans Cave, South Africa. Journal of Human Evolution, 57, 688-696.
Hajdas, I., Ivy-Ochs, S., Pickering, R., Preusser, F. 2008. Recent developments in Quaternary dating methods. Geographica Helvetia 1, 1-5.
Pickering, R., Hancox, P.J., Lee-Thorp, J.A., Grün R., Mortimer, G.E., McCulloch, M. & Berger, L.R. 2007. Stratigraphy, U-series chronology and palaeoenvironments at Gladysvale Cave: insights into the climatic control of South African hominin bearing caves, South Africa, Journal of Human Evolution, 53, 602-619.
Ustaszewski, M., Herwegh, M., McClymont, A.F., Pfiffner, A.O., Pickering, R. & Preusser, F. 2007. Unravelling the evolution of an Alpine to post-glacially active fault in the Swiss Alps, Journal of Structural Geology, 29, 1943-1959.
Hall, G., Pickering, R., Lacruz, R., Hancox, P.J., Berger, L.R & Schmid, P. 2006. An Acheulean handaxe from Gladysvale Cave Site, Gauteng, South Africa. South African Journal of Science, 102, 103-105.
Pickering, R. 2006. Regional geology, setting and sedimentology of the Middle Stone Age deposits at Sibudu Cave, KwaZulu-Natal, South Africa. Southern African Humanities 18 (1): 123-29.