From reef to pelagic and evaporite evolution of transgressive and regressive successions in the northwestern part of the Malatya Mesozoic basin, east Anatolia of Turkey

摘要

Malatya basin is located in the southern Taurus-Anatolian Platform, which acted as a part of the Mediterranean Province of the Tethyan Realm through Cretaceous time. In the study area, the transgressive unit was started with patch reefs which unconfor-mably overlie ophiolitic basement or directly rest on terrestrial sediments with gradual transition of siliciclastic shore passing upward into siliciclastic-dominated turbidites and followed by pelagic-bearing calciturbidites. The transgressive unit was terminated by a shallow water carbonate deposition composed of generally coral- and loftusia sp.- bearing banks and local coal-bearing coastal swamp. Evaporites were precipitated as last depositional phase of the regressive unit, represented by individual outcrops running along the northeast margin of the basin. This situation suggests that a sulphate platform was developed from north to south. 87Sr/86Sr isotopic values obtained from evaporates are consistent with that those of seawater values of the Uppermost Cretaceous time. The studied unit consists of a superimposed deposition which is resulted from transgressive and regressive episodes of the Upper Cretaceous sea (Campanian to Maastrichtian), accompanied with regional tectonic and paleoclimatic changes in the east Anatolian inner basins.