TY - JOUR

T1 - Paleostress pattern and salt tectonics within a developing foreland basin (north-western Subhercynian Basin, northern Germany)

AU - Brandes, Christian

AU - Schmidt, Carolin

AU - Tanner, David Colin

AU - Winsemann, Jutta

N1 - Funding Information: Acknowledgments We are grateful to W. Stackebrandt and an anonymous reviewer for their constructive and helpful comments. Financial support by the Niedersächsisches Ministerium für Wissen-schaft und Kultur (MWK) is gratefully acknowledged (PRO Nie-dersachsen Project No. 11.2-76202-17-3109). We would like to thank Bernhard Cramer, Frank Wiese, Volker Wilde and Frank Wrobel for discussion. Janine Meinsen is acknowledged for help with GOCAD and Jörg Lang is thanked for discussion. Hans-Peter Blohm is thanked for the permission to enter the protected areas and help in the field. Midland Valley Exploration Ltd. is gratefully acknowledged for the use of their software package Move.

PY - 2013/11

Y1 - 2013/11

N2 - Analysing the paleostress field in sedimentary basins is important for understanding tectonic processes and the planning of drilling campaigns. The Subhercynian Basin of northern Germany is a perfect natural laboratory to study the paleostress field in a developing foreland basin. The simple layer-cake geometry of the basin-fill is dominated by several piercing and non-piercing salt structures. We derived the paleostress field from the orientation of fracture sets, faults, slickensides and stylolites. On a regional scale, the basin-fill is characterized by a horizontal compressional paleostress vector that is mainly NNE-SSW-oriented, which reflects the Late Cretaceous inversion phase in Central Europe. We show that the local paleostress field is distinctly perturbated due to the salt structures. Along the edge of the salt pillows, the maximum horizontal paleostress vector is deflected by up to 90° from the regional trend. In the case of the Elm salt pillow, it forms a radial pattern. Restoration of balanced cross-sections demonstrates at least 9 % of the shortening of the north-western part of the Subhercynian Basin was achieved by folding. The salt structures in the north-western Subhercynian Basin are the result of varying stress conditions. Initial extension in the Triassic caused first salt movements that prevailed during the Jurassic and Early Cretaceous. Most important is the Late Cretaceous contractional phase that shortened the diapirs and led to the formation of the salt pillows between diapirs due to detachment folding. We derive four main controlling factors for such salt-dominated contractional basins: (1) the wedge-shape basin-fill is the product of the dynamic load at the southern margin of the basin, (2) a basal salt layer fed the diapirs and acted as a detachment horizon during the later shortening, (3) detachment folding was the dominating deformation mechanism during contraction, and (4) the pre-existing diapirs controlled the position of the detachment folds.

AB - Analysing the paleostress field in sedimentary basins is important for understanding tectonic processes and the planning of drilling campaigns. The Subhercynian Basin of northern Germany is a perfect natural laboratory to study the paleostress field in a developing foreland basin. The simple layer-cake geometry of the basin-fill is dominated by several piercing and non-piercing salt structures. We derived the paleostress field from the orientation of fracture sets, faults, slickensides and stylolites. On a regional scale, the basin-fill is characterized by a horizontal compressional paleostress vector that is mainly NNE-SSW-oriented, which reflects the Late Cretaceous inversion phase in Central Europe. We show that the local paleostress field is distinctly perturbated due to the salt structures. Along the edge of the salt pillows, the maximum horizontal paleostress vector is deflected by up to 90° from the regional trend. In the case of the Elm salt pillow, it forms a radial pattern. Restoration of balanced cross-sections demonstrates at least 9 % of the shortening of the north-western part of the Subhercynian Basin was achieved by folding. The salt structures in the north-western Subhercynian Basin are the result of varying stress conditions. Initial extension in the Triassic caused first salt movements that prevailed during the Jurassic and Early Cretaceous. Most important is the Late Cretaceous contractional phase that shortened the diapirs and led to the formation of the salt pillows between diapirs due to detachment folding. We derive four main controlling factors for such salt-dominated contractional basins: (1) the wedge-shape basin-fill is the product of the dynamic load at the southern margin of the basin, (2) a basal salt layer fed the diapirs and acted as a detachment horizon during the later shortening, (3) detachment folding was the dominating deformation mechanism during contraction, and (4) the pre-existing diapirs controlled the position of the detachment folds.

KW - 3D subsurface model

KW - Paleostress field

KW - Salt diapir

KW - Salt pillow

KW - Structural restoration

KW - Subhercynian basin

UR - http://www.scopus.com/inward/record.url?scp=84885918278&partnerID=8YFLogxK

U2 - 10.1007/s00531-013-0911-7

DO - 10.1007/s00531-013-0911-7

M3 - Article

AN - SCOPUS:84885918278

VL - 102

SP - 2239

EP - 2254

JO - International Journal of Earth Sciences

JF - International Journal of Earth Sciences

SN - 1437-3254

IS - 8

ER -