publisher = {Selbstverlag Fachbereich Geowissenschaften, FU Berlin},

abstract = {At the beginning of Late Jurassic both the Lochen (LA) and the Cracow areas (CA) were palaeotopographic highs in an epicontinental basin located at the stable northern margin of the Tethyan Ocean. The topographically high position of the LA was probably caused by intensive carbonate production which proceeded on a small sea-floor bulge located close to the boundary between middle and lower parts of the low-angle carbonate ramp. Lack of deep structural control of this rise caused prograding facial unification during the Oxfordian and Kimmeridgian and led to gradual disappearance of the LA individuality in relation to the neighbouring areas. The topographical high of the CA resulted from anomalously low subsidence rate in comparison to the adjacent areas which has lasted at least for the whole Oxfordian. Low subsidence directly gave rise to the development of a barrier (so-called Cracovian Platform) which separated the interior basin in the north from the deeper parts of the basin in the south. Topography of the Polish part of epicontinental basin along the Czestochowa-Cracow line corresponds to the low-gradient rimmed carbonate shelf which graded laterally (to the northeast and east) into the low-angle carbonate ramp. Stratigraphic subdivision of Upper Jurassic strata is very precise in the LA and rather poor in the CA due to scarcity of ammonites in the massive facies which predominates in the latter area. However, ammonite fauna from both areas belongs to the same German-Polish Submediterranean Subprovince which allows to attempt the correlation of lithologies and determination of factors which controlled deposition. Both the studied areas show distinct differences in the development of carbonate buildups. In the LA the main components of carbonate buildups during whole Oxfordian and the Early Kimmeridgian were siliceous sponges and microbolites whilst in the CA the flourishing growth of microbolites and gradual decline of siliceous sponges domination took place during the Late Oxfordian. The sediment was initially diversified into the two varieties: that formed by siliceous sponges and the microbolites incipient rigid framework, and the soft mud. In such carbonate buildups stromatactis cavities might have developed even in early diagenesis due to internal erosion of the soft mud. The principal reason of the internal erosion was turbulent water flow through the sediment. However, in generally low-energy sedimentary environments such flow could be triggered by submarine gravity flows or strong bottom currents. Pseudonodular textures encountered in carbonate buildups in both the areas resulted from shallow-burial diagenesis. During the burial diagenesis some parts of the sediment has been disintegrated under the pressure of overlying strata owing to the existing open spaces and different susceptibility to compaction showed by the incipient rigid framework and the soft sediment. Deposition in the LA was controlled mainly by sea-level pulses and ecological factors. In the CA principal control was provided by subsidence rate supported by synsedimentary tectonics, sea-level changes and ecological factors. All these controlling factors were variable in time which provoked changes in carbonate production rates from intensive, aggradational growth of the buildups to drowning of the carbonate ramp and rimmed shelf. The drowning of carbonate ramp on which the LA was located took place at the Oxfordian/Kimmeridgian break. It is documented by spectacular development of redeposited pelagites of skeletal-calciturbidites type with abundant fragments of Saccocoma sp. which have appeared for the first time in mass quantities in the Upper Jurassic. By analogy, it can be inferred that in the CA similar Saccocoma-calciturbidites prove the drowning of rimmed shelf related to the same trangressive event at the Oxfordian/Kimmeridgian break.},
note = { \url {http://resolver.sub.uni-goettingen.de/purl?gldocs-11858/11583}},
note = { \url {http://dx.doi.org/10.23689/fidgeo-5965}},
}