Description: The Cameros Basin (North Spain) is a Late Jurassic-Early Cretaceous extensional basin, which was inverted during the Cenozoic. It underwent a remarkable thermal evolution, as indicated by the record of anomalous high temperatures in its deposits. In this work the subsidence and thermal history of the basin is reconstructed, using subsidence analysis and 2D thermal modeling. Tectonic subsidence curves provide evidence of the occurrence of two rapid subsidence phases during the syn-extensional stage. In the first phase (Tithonian-Early Berriasian), the largest accommodation space was formed in the central sector of the basin, whereas in the second (Early Barremian-Early Albian), it was formed in the northern sector. These rapid subsidence phases could correspond to relevant tectonic events affecting the Iberian Plate at that time. By distinguishing between the initial and thermal subsidence and defining their relative magnitudes, Royden's (1986) method was used to estimate the heat flow at the end of the extensional stage. A maximum heat flow of 60-65 mW/m 2 is estimated, implying only a minor thermal disturbance associated with extension. In contrast with these data, very high vitrinite reflectance, anomalously distributed in some case with respect to the typical depth-vitrinite reflectance relation, was measured in the central-northern sector of the basin. Burial and thermal data are used to construct a 2D thermal basin model, to elucidate the role of the processes involved in sediment heating. Calibration of the thermal model with the vitrinite reflectance (%Ro) and fluid inclusion (FI) data indicates that in the central and northern sectors of the basin, an extra heat source, other than a typical rift, is required to explain the observed thermal anomalies. The distribution of the %Ro and FI values in these sectors suggests that the high temperatures and their distribution are related to the circulation of hot fluids. Hot fluids were attributed to the hydrothermal metamorphic events affecting the area during the early post-extensional and inversion stages of the basin. This article is protected by copyright. All rights reserved.

Description: Seismic interpretation and structural modelling of the Rotliegend along the northern limit of the Northeast German Basin Dirk Kossow, Holger Rieke, Tommy McCann, Robert Ondrak, *Manfred Strecker, Jörg F.W. Negendank GeoForschungsZentrum Potsdam, PB 3.3. "Sedimente und Beckenbildung", Telegrafenberg, 14473 Potsdam *Universität Potsdam, Mathematisch-Naturwissenschaftliche Fakultät, Institut für Geowissenschaften, 14469 Potsdam Following the cessation of compressive Variscan movement, Central Europe was characterized by a period of widespread basin formation accompanied by extensive magmatic activity (Ziegler 1990). In the study area, basin development is linked with activities along the TESZ, leading to a complex relationship between sedimentation and tectonics. To study the Lower Permian basin morphologies and depositional architectures along-strike of the initial northern limit of the Northeast German Basin, an extensive database consisting of core material and a network of commercial seismic profiles have been used. In the area several NW-SE-trending subbasins are developed. However, the internal structure of these basins and, therefore, the depositional pattern is controlled by the development of approximately N- to NE-trending half grabens reflecting E-W extension during this time. The observed structural style is interpreted as the brittle response to deep-seated ductile deformation along the NW-trending Trans-European Fault (Berthelsen 1992). Dextral crustal shearing had its near-surface expression in the development of N-trending normal faults. Forward modelling using STRETCH (Kuznir et al. 1991) has been used to attempt to quantify the tectono-sedimentary evolution during and after the phase of extension. The program is based on the flexural cantilever model of continental lithosphere extension and is able to compute the complex interference pattern which is induced by the presence of many faults of different size, position and polarity along an investigated profile. Sediment loading, erosional unloading as well as compaction of the syn-rift sediments may be included. Furthermore, the post-rift phase which is mainly characterised by thermal subsidence can be calculated. The analysis showed that extension by multiple faults has resulted in a complex interference pattern between the flexural footwall uplift and hangingwall collapse of each fault. In this phase of mechanical extension the basin geometry and deposition were largely controlled by the fault pattern resulting from the overall extension. Faulting led to rapid thickness variations across the tilted blocks producing a complex sedimentation pattern. The response to the subsequent post-rift stage was the gradual peneplanation of the fault-generated topography. In the study area post-rift thermal subsidence led to deepening of the basin and produced a simpler depositional pattern with a thickening towards the basin centre. The post-rift sediment package overlies the syn-faulted sediments and extends across the former basin margins. By integrating geological and geophysical data, analysis of the depositional and structural development resulted in an improved understanding of the geodynamic evolution of the Lower Permian succession in the region. REFERENCES: ZIEGLER, P. (1990): Geological atlas of western and central Europe. Elsevier, Amsterdam, 239 pp BERTHELSEN, A. (1992): From Precambrian To Variscan Europe. In: BLUNDELL, D., FREEMAN, R., MUELLER ST., A Continent Revealed - The European Geotraverse. Cambridge University Press pp153-164 KUZNIR, N.J., MARSDEN, G. & EGAN, S.S. (1991): A flexural-cantilever simple-shear/pure-shear model of continental lithosphere extension: applications to the Jeanne d' Arc Basin, Grand Banks and Viking Graben, North Sea. In: ROBERTS, A.M., YIELDING, G. & FREEMAN, B. The Geometry of Normal Faults London Geological Society Special Publication 56 41-60.