| Title | The changing architecture of sea-level lowstand deposits across the Mid-Pleistocene Transition: South Evoikos Gulf, Greece |
| Author | Anastasakis, G; Piper, D J W |
| Source | Quaternary Science Reviews vol. 73, 2013 p. 103-114, https://doi.org/10.1016/j.quascirev.2013.04.018 |
| Year | 2013 |
| Alt Series | Earth Sciences Sector, Contribution Series 20130240 |
| Publisher | Elsevier BV |
| Document | serial |
| Lang. | English |
| Media | paper; on-line; digital |
| File format | pdf; html |
| Area | Evoikos Gulf; Aegean Sea; Greece |
| Lat/Long WENS | 24.0000 24.5000 38.0000 37.5000 |
| Subjects | surficial geology/geomorphology; marine geology; continental shelf; coastal studies; sea level changes; sea level fluctuations; Pleistocene; sedimentation; Cenozoic; Quaternary |
| Illustrations | location maps; seismic profiles; logs |
| Program | GSC Atlantic Division, Director Office |
| Abstract | directly dependent on relative sea-level changes. In the past w0.6 Ma, sea-level change has been dominated by asymmetric 100 ka eustatic sea-level cycles, whereas the record of sea-level changes in
earlier Pleistocene progradational sequences is less clear. In a steadily subsiding basin in which accommodation balances sediment flux, the depth of a eustatic lowstand determines the paleo-depth of
the deepest clinoform inflection point and the
seaward limit of the erosional transgressive surface, whereas the duration of a lowstand controls the amount of progradation that takes place. We report high-resolution seismic profiles of an exceptionally preserved coastal progradational sequence
from a coastal embayment in the Aegean Sea that is subsiding at w100 m/Ma. The seismic profiles show clinoforms of smaller amplitude and volume that were deposited before the 100 ka cyclic progradational units. This contrasts with literature reports
of complexity in progradational sequences at that time. We assume that published stacked benthic foram O-isotope records are a good proxy for the duration and a reasonable proxy for the amplitude of Pleistocene eustatic sea-level cycles. The MIS 6e5
eustatic sealevel rise is recognised based on sedimentation rates from cores. The underlying major progradational units are correlated with the long-duration, extreme lowstand 100 ka cycles of MIS 6, 12 and 16. Changes in the elevation of lowstand
inflection points in clinoforms are used to tentatively extend the record back to MIS 38, by comparison with the benthic foram proxy. The deposits of the higher and longer highstands of MIS 25, 31 and 37 are also recognised. This record provides a
testable template for future studies of short early Pleistocene sections on land and raises questions of detail about parts of the published d18O records. It independently supports the recent evidence that the Mid-Pleistocene transition was an abrupt
event, with an extreme lowstand in MIS 22. |
| Summary | (Plain Language Summary, not published)
This study reports a remarkable archive of sea-level change over the past 1.2 million years preserved in a coastal bay in Greece. The archive has been
imaged by seismic reflection profiling by a scientific colleague at the University of Athens. He sought my advice on interpretation based on my previous publications on similar data. Its importance is that it confirms that the first extreme lowstand
of sealevel during the ice ages of the past two million years took place 900, 000 years ago. The finding is applicable to understanding geological records in the offshore marine areas of Canada and potentially to more precise dating of Arctic
glacial events that are known to be approximately 1 million years old. |
| GEOSCAN ID | 293069 |
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