Paleobathymetry of Cretaceous Turbidite Basins of the East Alps Relative to the Calcite Compensation Level

Abstract

The paleobathymetry of ancient turbidite basins has traditionally been dealt with in terms of paleontologic depth indicators. The calcite compensation depth now provides an additional bathymetric reference level. In this study the concept of carbonate compensation levels (CCL) has for the first time been applied in detail to Cretaceous turbidite basins. Out of the four East Alpine basins studied two (i.e., Flysch Zone of the East Alps and Kossen Gosau Basin) have calcite-free hemipelagic green claystones of Campanian-Early Maestrichtian age and were below the CCL. Alternative causes such as climatic variations and terrigenous influx of carbonate-free detritus are unlikely to be major controlling factors for the absence of calcite in the hemipelagic claystones. Distinction between hemipelagic and turbiditic mudstones is facilitated by the high calcium carbonate content of the latter. Hemipelagic and pelagic layers of the same age in the other two basins (Reichenhall Gosau Basin and Ultrahelvetic flysch) co...