TY - JOUR
T1 - Paleoanthropologically significant South African sea caves dated to 1.1-1.0 million years using a combination of U-Pb, TT-OSL and palaeomagnetism
AU - Pickering, Robyn
AU - Jacobs, Zenobia
AU - Herries, Andy I R
AU - Karkanas, Panagiotis
AU - Bar-Matthews, Miryam
AU - Woodhead, Jon D.
AU - Kappen, Peter
AU - Fisher, Erich
AU - Marean, Curtis
N1 - Funding Information:
Acknowledgements to the MAP staff for their assistance and competence in the field, the Dias Museum for use of their facilities, SAHRA and HWC for permits. Funding received from the Swiss National Research Foundation ( PBBEP2-126195 to RP), Australian Research Council ( FT120100399 to AIRH), the US National Science Foundation (grants # BCS-9912465 , BCS-0130713 , and BCS-0524087 to CWM), the Hyde Family Foundation , the Institute of Human Origins at Arizona State University , and Arizona State University. The palaeomagnetic analysis was undertaken by AIRH at the University of Liverpool Geomagnetism Laboratory with the support of Mimi Hill. The synchrotron analysis was undertaken on the XFM beamline at the Australian Synchrotron (beamtime granted to AIRH, PK and RP). Thanks to Mark Foster and Ben Elliot for assistance with rock climbing and rope access work needed for the exploration and sampling of PPOH and PP13G. We would like to thank two anonymous reviewers for their thorough and constructive comments.
PY - 2013/4/1
Y1 - 2013/4/1
N2 - Deposits in sea caves found along the southern coastline of South Africa have produced a rich and detailed archaeological record of early modern humans. There is, however, little evidence for coastal cave deposits and human occupation older than MIS5e (~120 ka). Based on the correlation of four different chronological methods we present evidence for remnant cave deposits of 1.1-1.0 Ma from the quartzite sea cliff of Pinnacle Point, near Mossel Bay. Initial uranium-thorium ages at isotopic equilibrium indicated an age of >500 ka for two flowstone layers, confirmed by uranium-lead dating of these flowstones from 1.099 ± 0.012 to 1.047 ± 0.011 Ma. TT-OSL (thermally transferred optically stimulated luminescence) provides an age of 1.02 ± 0.088 Ma for the sand grains imbedded in the tufa underlying the flowstone and 0.720 ± 0.066 to 0.665 ± 0.056 for the overlying beach sediments, producing an internally consistent age sequence centring on 1.0-1.1 Ma. The normal palaeomagnetic signal of the younger section of the flowstone is interpreted to represent the Jaramillo between 1.07 and 0.99 Ma. There is a clear hiatus in the middle of this flowstone, leading us to interpret the lower normal signal as the Punaruu event at ~1.115-1.1051 Ma. Together these four techniques point to an age of 1.1-1.0 Ma for these cave deposits at Pinnacle Point, far older than anticipated. The persistent presence of these 1.1-1.0 Ma deposits means that the enigmatic lack of Earlier Stone Age (Acheulean) artefacts in the sea caves along this coastal region can no longer be explained entirely by the age of the caves or through removal of sediments by previous sea level highstands. We believe that these and other coastal caves from this region, if located high enough above sea level, may contain deposits of great antiquity, which could provide outstanding records of climate, environment, sea level change, and human occupation back into the early to middle Pleistocene.
AB - Deposits in sea caves found along the southern coastline of South Africa have produced a rich and detailed archaeological record of early modern humans. There is, however, little evidence for coastal cave deposits and human occupation older than MIS5e (~120 ka). Based on the correlation of four different chronological methods we present evidence for remnant cave deposits of 1.1-1.0 Ma from the quartzite sea cliff of Pinnacle Point, near Mossel Bay. Initial uranium-thorium ages at isotopic equilibrium indicated an age of >500 ka for two flowstone layers, confirmed by uranium-lead dating of these flowstones from 1.099 ± 0.012 to 1.047 ± 0.011 Ma. TT-OSL (thermally transferred optically stimulated luminescence) provides an age of 1.02 ± 0.088 Ma for the sand grains imbedded in the tufa underlying the flowstone and 0.720 ± 0.066 to 0.665 ± 0.056 for the overlying beach sediments, producing an internally consistent age sequence centring on 1.0-1.1 Ma. The normal palaeomagnetic signal of the younger section of the flowstone is interpreted to represent the Jaramillo between 1.07 and 0.99 Ma. There is a clear hiatus in the middle of this flowstone, leading us to interpret the lower normal signal as the Punaruu event at ~1.115-1.1051 Ma. Together these four techniques point to an age of 1.1-1.0 Ma for these cave deposits at Pinnacle Point, far older than anticipated. The persistent presence of these 1.1-1.0 Ma deposits means that the enigmatic lack of Earlier Stone Age (Acheulean) artefacts in the sea caves along this coastal region can no longer be explained entirely by the age of the caves or through removal of sediments by previous sea level highstands. We believe that these and other coastal caves from this region, if located high enough above sea level, may contain deposits of great antiquity, which could provide outstanding records of climate, environment, sea level change, and human occupation back into the early to middle Pleistocene.
KW - Geochronology
KW - Palaeomagnetism
KW - Pinnacle Point
KW - South African cave deposits
KW - TT-OSL dating
KW - U-Pb dating
UR - http://www.scopus.com/inward/record.url?scp=84873551829&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84873551829&partnerID=8YFLogxK
U2 - 10.1016/j.quascirev.2012.12.016
DO - 10.1016/j.quascirev.2012.12.016
M3 - Article
AN - SCOPUS:84873551829
SN - 0277-3791
VL - 65
SP - 39
EP - 52
JO - Quaternary Science Reviews
JF - Quaternary Science Reviews
ER -