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Basin modelling of a lignite‐bearing salt rim syncline: insights into rim syncline evolution and salt diapirism in NW G ermany
Author(s) -
Brandes Christian,
Pollok Lukas,
Schmidt Carolin,
Wilde Volker,
Winsemann Jutta
Publication year - 2012
Publication title -
basin research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.522
H-Index - 83
eISSN - 1365-2117
pISSN - 0950-091X
DOI - 10.1111/j.1365-2117.2012.00544.x
Subject(s) - syncline , geology , structural basin , diapir , paleontology , fold (higher order function) , anticline , structural geology , subsidence , geochemistry , mechanical engineering , engineering
The H elmstedt‐ S taßfurt salt wall is 70 km long, 6–8 km wide and one of the most important diapiric structures in northern G ermany, based on the economically significant lignite‐bearing rim synclines. The analysed S chöningen rim syncline, located on the southwestern side of the H elmstedt‐ S taßfurt structure, is 8 km long and 3 km wide. The basin‐fill is up to 366 m thick and characterized by 13 major lignite seams with thicknesses between 0.1 and 30 m. The key objectives of this article were to expand on the classical cross‐section based rim syncline analysis by the use of 3 D models and basin simulations. Cross‐sections perpendicular to the basin axis indicate that the basin‐fill has a pronounced lenticular shape. This shape varies from more symmetric in the NW to clearly asymmetric in the SE . Isopach maps imply a two‐fold depocentre evolution. The depocentre migrated over time towards the salt wall and also showed some distinct shifts parallel to the salt wall. The basin modelling part of the study was carried out with the software PetroMod ® , which focused on the burial history of the rim syncline. Modelling results also show the progressive migration of the rim syncline depocentre towards the salt wall. The present‐day asymmetry of the basin‐fill was already developed in the early phases of rim syncline evolution. The extracted geohistory curve shows initial rapid subsidence between 57 and 50 Ma and more moderate subsidence from 50 to 34 Ma. This pattern is interpreted to reflect salt evacuation from the source layer into the salt wall. The initial salt‐withdrawal rate was rapid, but later decreased probably due to depletion of the source layer.