The thermal history of the western lower Saxony Basin, Germany

Since about 30 years the maturity and geophysical anomalies within the Lower Saxony Basin (LSB) were interpreted as a result of a deep lying igneous intrusion called “Bramsche Massif”. Based on the lignite/subbituminous coal stage of Upper Campanian rocks overlying the Lower Cretaceous units, a late Early Cretaceous or early Late Cretaceous age was concluded for the time of intrusion. Vitrinite reflectances for the central and southern part of the LSB confirm a low reflectance increase with depth which is more likely caused by deep burial of the Jurassic to Carboniferous sequence at only moderate heat flows than by an igneous intrusion. Due to inversion tectonics in the Coniacian/Santonian, the LSB developed to the Lower Saxony Tectogene. During this inversion, the basin fill was uplifted and partly thrusted on the surrounding swells. Contemporaneous significant erosion uncovered Triassic up to Paleozoic sediments in the basin. Estimations of maximum burial depths and thicknesses of then eroded sedimentary rocks range from about 3500 to 8000 m. The highest former overburdens were deduced for the centre of the basin and mostly for Jurassic and Cretaceous sequences. Towards the basin margins, erosion thicknesses decrease. An explanation for the differences of eroded thicknesses might be variable synsedimentary subsidence within the LSB during late Jurassic and early Cretaceous times due to rift and wrench tectonics. Due to the extension, graben and secondary halfgraben systems were formed. In the course of the compressional phase during the inversion period, these areas became those with strongest uplift. Investigations on zircon and apatite fission tracks indicate a complex thermal history of the basin. The data imply that the Lower Saxony Basin has experienced three thermal heating events after the deposition of the Carboniferous. Moreover, fission track ages imply that the high thermal maturity of the organic matter in the centre of the Lower Saxony Basin was already obtained in the Upper Jurassic/Early Cretaceous. These findings would ask for much higher sedimentation rates during Upper Jurassic and earliest Cretaceous times than previously assumed.

Grantor dc:publisher

Publikationsserver der RWTH Aachen University

Year dc:date

2008

Author dc:creator

• Adriasola Muñoz, Yvonne

Contributors dc:contributor

• Littke, Ralf

• info:eu-repo/classification/ddc/550
• Niedersächsisches Becken <West>
• Inkohlung
• Erosion
• Kohlenwasserstoffe
• Inversion <Geologie>
• Geowissenschaften
• Spaltspuren
• Flüssigkeitseinschlüsse
• struckturelle Rekonstruktion
• Beckenmodellierung
• fission tracks
• fluid inclusions
• structural balancing
• basin modelling

Statement dc:rights

• info:eu-repo/semantics/openAccess

Language dc:language

eng

Identifier

https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-112499%22

OAI record oai:identifier

https://publications.rwth-aachen.de/oai2d?verb=GetRecord&metadataPrefix=oai_dc&identifier=oai%3Apublications.rwth-aachen.de%3A49931