科研之友
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摘要
A ca. 320 m thick composite section (Goppling section) of a turbidite-rich deep-water system outcropping between Teisendorf and Oberteisendorf (Bavaria) encompasses the upper Maastrichtian to Ypresian (calcareous nannoplankton Zones CC25 to NP11). These deposits conformably overlie red clayey marlstone (Buntmergelserie). The whole succession is part of the Ultrahelvetic thrust unit, which is a detached part of the continental margin of the southern European Plate. In the latest Maastrichtian and early Paleogene, subsidence to below the calcite compensation depth coeval with the onset of turbidite sedimentation indicates the development of slope-basins by subsiding crustal fault blocks. These basins acted as sediment traps and caused a dearth of turbidite sedimentation in the adjoining Penninic basin. During the Danian, turbidites in the Goppling slope-basin were deposited from currents, that flowed parallel with the E-W-trending basin axis and the strike of the slope. In the Selandian, sedimentation rates outpaced subsidence rates and the basin filled up to the spill-point. This is indicated by a shift in the section from sand-rich to mud-rich lithologies and a change from basin-axial to downslope (N-S) paleotransport directions. Turbidites were deposited on the smooth bathymetry of the filled basin due to the reduction of slope gradient. Another pulse of subsidence formed a new depression at this site in the Ypresian and caused the deposition of a sand-rich turbidite succession from longitudinal flowing turbidity currents. For the entire deep-water system overlying the Buntmergelserie, the new lithostratigraphic term Achthal Formation is introduced.
- 出版日期2010
