On the origin of the Southern Permian Basin, Central Europe

A detailed study of the structural and stratigraphic evolution of the South ern Permian Basin during latest Carboniferous to Early Jurassic times, supp orted by quantitative subsidence analyses and forward basin modelling for 2 5 wells, leads us to modify the conventional model for the Rotliegend-Zechs tein development of this basin. The Late Permian-Early Jurassic tectonic su bsidence curves are typical for a Permian to Early Triassic extensional sta ge that is followed by thermal subsidence. However, a purely extensional mo del is extremely problematic because active faulting during this time is 'm inor' and generally hard to document. Using inverse techniques to model the subsidence curves, we quantitatively show that a significant component of Late Permian and Triassic tectonic subsidence can be explained by thermal r elaxation of Early Permian lithospheric thinning, and by delayed infilling of paleo-topographic depressions that developed during the Early Permian. I n this interpretation, Stephanian-Autunian wrenching resulted in thermal de stabilisation of the lithosphere. deep fracturing of the crust, disruption and erosion of its sedimentary cover and regional uplift of the area of the future Southern Permian Basin. Upon termination of wrench tectonics and as sociated volcanism, towards the end of the Autunian, the Southern Permian B asin began to subside in response to thermal contraction of the lithosphere . The evolving basin was isolated from the World oceans and had subsided po ssibly up to some 700 m below their level at the beginning of Upper Rotlieg end sedimentation. After catastrophic flooding of this paleotopographic dep ression at the beginning of the Zechstein, changing sea level, sedimentatio n and subsidence rates remained essentially in balance. Although the effect s of Triassic rifting overprinted parts of the Southern Permian Basin, its overall subsidence pattern persisted well into the Jurassic. In contrast to the remainder of the Southern Permian Basin, Permian and Triassic crustal extension contributed significantly to the subsidence of the Polish Trough. (C) 2000 Elsevier Science Ltd. All rights reserved.