Stratigraphic Signatures of the Tectonic and Eustatic Effects During the Post-Rift History of the Tethyan Margin in the Southern Vercors (France): ABSTRACT

Abstract

The stratigraphic record of the southern European peri-tethyan platforms displays numerous major transgressive/regressive facies cycles with a duration of more than 10 m.y. during Mesozoic time. In the sub-Alpine basin, southeastern France, shaly sediments dominate during transgressive phases, and calcareous sediments dominate during regressive phases. These major facies cycles relate to major tectonic events associated with the tethyan passive margin history. It appears that these major facies cycles are formed in time intervals bracketed by periods of significant increases in the rate of tectonic subsidence. They are interpreted as second-order tectonic events (the evolution of the sedimentary basin being of first order). At a smaller scale, depositional sequences with lowstand, transgressive and highstand systems tracts are recognizable within the major transgressive/regressive facies cycles. They are interpreted to be caused by third-order eustatic cycles. During periods of high rates of tectonic subsidence, the accommodation space increases on the shelf. Thick transgressive and highstand systems tracts develop. These thick shelfal sequences are characteristic of the transgressive phase of the major facies cycles. When the rate of tectonic subsidence decreases, the accommodation space on the shelf also decreases, which greatly enhances the effect of eustatic sea level falls. During the regressive phase of more » the major facies cycles, depositional sequences develop thick lowstand systems tracts in the basin and major subaerial exposure surfaces on the shelf. « less