--> Deceleration of Sea-Level Rise at 8000-7000 Years B.P. as the Dominant Factor in Progradation of Holocene Marine Deltas, by D. J. Stanley and A. G. Warne; #90986 (1994).

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Abstract: Deceleration of Sea-Level Rise at 8000-7000 Years B.P. as the Dominant Factor in Progradation of Holocene Marine Deltas

Daniel Jean Stanley, Andrew G. Warne

Stratigraphic analysis of radiocarbon-dated core sections recovered in modern deltas in the Mediterranean Sea and other world oceans indicates that many, if not most, of these depocenters took on their present form about 8000 to 7000 years ago. This short time span is one during which Holocene progradational series started to accumulate unconformably above late Pleistocene facies. These stratigraphic sequences were deposited in diverse settings, with variable sedimentary supply and processes, climatic conditions, geomorphologic configuration, tectonic framework and structural mobility. The significance of these Holocene sequences is that they relate directly to the marked deceleration in sea-level rise which began at 8000-7000 years B.P.

Deltaic sequences which record initial development at 8000-7000 years B.P. in the Mediterranean are the Nile delta in an arid setting on the North African margin and the Rhone in a more temperate setting on the southern Europe margin, both which began to form on gentle lowlands at about 7500 years B.P. In marked contrast is the coarser-grained Ebro delta which, at this time, accumulated at the base of highlands south of the Pyrenees. Deltas in other oceans and in a variety of climatic and geologic settings which also began to form between 8000 and 7000 years B.P. include the Mississippi and Yangtze, lying at about the same latitude as the Nile delta and, at other latitudes, the Orinoco, Nile, Alta (Norway), and various fjord-head deltas in British Columbia. The modem record indicates hat deceleration of sea-level rise is the dominant control resulting in initial progradation of marine deltas, and overprints other significant factors including geographic and tectonic setting and depositional conditions. These observations are pertinent in formulating stratigraphic models for the rock record.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994