Julian E. Andrews (J.Andrews@uea.ac.uk), Clive Portman, Peter J. Rowe,
Michael R. Leeder, Jenni Turner, and Jan Kramers1
School of Environmental Sciences, University of East Anglia, Norwich, NR4 7TJ, UK
1Institut für Geologie, Universität Bern, Baltzerstrasse 3, 3012 Bern, Switzerland
Uplifted marine isotope stage (MIS) 5e carbonate deposits in the Gulf of Corinth (GoC) demonstrate two rapid, sub-orbitally forced, sea-level oscillations in the early part of MIS 5e (Andrew et al., 2007). Microbial bioherms with inter-grown marine coralline algae are interpreted as early highstand deposits, forming at a time when climate was wet, such that enhanced runoff made the riverine end of the GoC brackish. Presence of thin vadose flowstone (speleothem) coating inter-bioherm surfaces mark a short-lived regression of >10 m, followed by sea-level recovery and re-establishment of the highstand, marked by coralline algae coating inter-bioherm cavity surfaces. These marine algae are then coated by a younger vadose flowstone, thick enough to provide an uncontaminated U/Th date of 134.8±2.0 ka. The dated flowstone is itself encrusted by marine fauna and the entire sequence overlain by highstand marine sediments and marine aragonite cements dated to 114-118 ka, part of the sustained MIS 5e highstand.
The age of the younger flowstone demonstrates that the early highstand occurred before 134.8±2.0 ka, and uplift arguments suggest that the bioherms are unlikely to be older than ~136 ka. These data are consistent with the notion that most of termination II (TII) sea level rise had occurred before 135 ka (e.g. see Gallup et al., 2002); indeed they suggest sea-level at this time reached about 2-4(±4) m below present sea level, 6-18 (±4) m higher than previous estimates. This early highstand was itself punctuated by a rapid sea-level oscillation of >10 m (as yet undated), and this oscillation, supported by new TII sea-level data from the Red Sea (Siddall et al. 2006), probably occurred in about 1000 years. The flowstone dated at 134.8±2.0 ka is interpreted to record the early part of the ‘Aladdin’s Cave’ regressive event from Papua New Guinea, although in Greece only the first 16 m of the event is recorded. The new data presented here support a recently published Red Sea TII sea-level curve: they also highlight minor discrepancies in the absolute dating of these early MIS 5e sea-level events worldwide.
We are currently in the process of U/Th dating flowstones and marine aragonites from the GoC that are associated with uplifted shorelines that are demonstrably (stratigraphic arguments) older than Holocene and younger than the MIS 5e deposits described above. We infer these are of MIS 5c age and await the data with considerable interest. We hope these new data will help constrain the height of MIS 5c highstands, about which there has been considerable disagreement. These inferred MIS 5c deposits are associated locally with wadi deposits, flowstones, and nearby tufa deposits, all of which suggest that regional palaeoclimate was particularly wet at this time, the first positive evidence of wet conditions since the early MIS 5e deposits described above.
Andrews, J.E., Portman, C., Rowe, P.J., Leeder, M.R., Kramers, J.D., 2007. Sub-orbital sea-level change
in early MIS 5e: new evidence from the Gulf of Corinth, Greece. Earth and Planetary Science Letters 259, 457-458.
Gallup, C.D., Cheng, H., Taylor, F.W., Edwards, R.L., 2002. Direct determination of the timing of sea level change during termination II, Science 295, 310-313.
Siddall, M., Bard, E., Rohling, E.J., Hemleben, C., 2006, Sea-level reversal during termination II, Geology, 34, 817-820.