Have Many Large Sedimentary Basins Originated in the Thermal Metamorphism of Their Lower Crust Due to Hotspot Heat Sources? The North German Permian Basin in a Global Review

Heinz-Juergen Brink
Consultant/University of Hamburg, Hannover, Germany

Since the stretching model appears to be not applicable to subsidence of accretionary crust, basins located on this crust type may have a particular origin. Examples of basins located on an accretionary crust are the West Siberia Basin and the North German Permian Basin. Both basins show, like many others, intensive volcanism and magmatism during the initial phase of the basin development. Remarkably, the West Siberia Basin is closely located to the (hotspot related) Siberian flood basalts with a similar Permotriassic age, and the location of the North German Permian Basin in Permian times is identical with the present day position of the Tibesti hotspot in Northern Africa. Since the Sichuan Basin in China, probably developed on a continental crust (!?), is closely located to flood basalts of similar age (Emeishan) as well, it is assumed that a relation between the evolution of these basins and hotspot heat sources of the underlying Earth mantle may exist. Due to these heat sources, thermal metamorphism within the lower layers of the (accretionary) crust may occur, resulting in rock density increase and subsequent shrinkage of the effected rock volumes. These shrinkage processes will lead to the development of topographic lows, their filling with sedimentary debris, and the subsequent ignitions of exponential declining isostatic/metamorphic basin subsidence. Analyses of metamorphic processes, potential field anomalies, temperature fields, and histories of subsidence have been integrated into a model that can especially explain the development of the North German Permian Basin. Other traces of the East African Rift Hotspot and the Eifel Hotspot, which affected some of the overriding drifting continental plates, are investigated, too, and either linked to the Afar flood basalts and the evolution of the Dniepr-Donets Basin or to the North Sea Basin. Continental drift templates, present day hotspot locations, flood basalt areas, metamorphic facies as function of temperature, and crust categories are taken as given.

AAPG Search and Discover Article #90066©2007 AAPG Hedberg Conference, The Hague, The Netherlands

AAPG Search and Discover Article #90066©2007 AAPG Hedberg Conference, The Hague, The Netherlands