Tectonic evolution of the Western Eger rift: a tale of two faults

Tectonophysics, 2009

Quaternary Science Reviews, 2005

The Roer valley rift system (RVRS) is located in the northern prolongation of the upper Rhine Graben. During the Cenozoic, the evolution of the RVRS was influenced by two different rift systems situated in the North and in the South (the North Sea rift system and the West European rift system, respectively). During the last decades, moderate seismicity revealed the continuous activity of the graben border faults (the Peel Boundary fault zone -PBFZ- and the Feldbiss fault zone-FFZ-). We use a high precision digital elevation model (DEM) to characterize and quantify the present-day deformation along these faults. The fault pattern shows similarity to a strike-slip structure. However, analysis of the DEM reveals that the Recent to Quaternary formations and landforms affected by the fault activity are only vertically offset. This suggests a pure normal faulting mode for the main border faults and a direction of extension perpendicular to the graben (i.e., NE–SW). Quantification of the offset dated markers allows the determination of the displacement rates along the fault segments. In the southeastern part of the RVRS, the vertical displacement rates inferred for the FFZ and the southeastern PBFZ range between 55 and 65 mm/ky and around 65 mm/ky, respectively. In contrast, the displacement rates determined for the northwestern segment of the PBFZ are around 200 mm/ky. We explain these differences between the northwestern and southeastern parts of the RVRS by the large-scale geometry of the graben, the RVRS being symmetric in the south-east and asymmetric (half-graben) in the north-west. The deformation is accommodated by two border faults (FFZ and the south-eastern part of the PBFZ) in the south-east and by only one fault in the north-west (the north-western segment of the PBFZ). In addition, the thickness of the Neogene main depocentre in the northwestern half of the RVRS indicates a larger amount of extension in this part of the graben than in the south-east. The combination of the graben geometry and the amount of extension can explain the differences in the displacement rate.

Earth and Planetary Science Letters, 2014

Available online xxxx Editor: T.M. Harrison Keywords: thermal inheritance detrital thermochronology margin inversion inverse modeling Pyrenees

Tectonophysics, 2005

Quaternary Science Reviews, 2005

The West Netherlands Basin (WNB) and the neighbouring Roer Valley Rift System (RVRS) form the most prominent tectonic features of the onshore Netherlands. The two basins have a common tectonic origin and similar Mesozoic evolution, their Neogene–Quaternary evolution, however, is markedly different. While the WNB is tectonically/seismically inactive and is characterised by uniform Neogene–Quaternary subsidence, in the RVRS fault controlled intra-plate deformation has taken place since Late Oligocene times with pronounced seismic activity. Considering the present-day NE–SW regional extension as well as the similar basin orientation and Mesozoic evolutions one would not expect strikingly different neotectonic activity in the two basins. Detailed analysis of Mesozoic, Tertiary and Quaternary fault patterns revealed that (1) the Palaeozoic–Mesozoic tectonic fabric has great influence on the Cenozoic deformation style of the basin system; (2) present-day faulting in the RVRS is related to the reactivation of pre-existing faults and (3) the Mesozoic fault pattern is slightly different in the two basins. Using a novel technique (three-dimensional (3-D) slip tendency analysis) we aim to determine whether these differences in fault orientation are substantial enough to produce significantly different resolved stresses along the faults. This modelling not only tests a common geological phenomena but indirectly also delivers important constraints regarding the origin of faulting in the study area. During the analysis 3-D geometric models of 84 mapped faults were investigated. The results of this recently developed modelling technique reveal that the faults in both basins should behave similarly under the condition of a laterally homogeneous regional stress field, which is in disagreement with the present-day tectonic activity of the region. On the other hand the modelling also reveals that the predicted tendency of slip is very sensitive to the ratio of the minimum horizontal and the vertical stress (S). As an explanation for the pronounced fault activity in the RVRS and the tectonic quietness of the WNB it is proposed that either the regional extension in the WNB is “weaker” (in term of higher S ratio) than that in the RVRS or the slip thresholds in the two basins are different. The study emphasised that differentiation in the tectonic evolution has already started in the Tertiary, therefore, it is reasonable to assume that the different tectonic stress field and/or slip threshold between the two areas is directly related to the origin of the Cenozoic rifting in the RVRS. Several hypotheses are discussed to account for these two possibilities, taking into account the lithospheric structure and the Cenozoic tectonic evolution of the two basins as well as surrounding areas.

Geology, 1998

A mechanism to explain rift-basin subsidence and stratigraphic patterns Email alerting services articles cite this article to receive free e-mail alerts when new www.gsapubs.org/cgi/alerts click Subscribe to subscribe to Geology www.gsapubs.org/subscriptions/ click Permission request to contact GSA http://www.geosociety.org/pubs/copyrt.htm#gsa click official positions of the Society. citizenship, gender, religion, or political viewpoint. Opinions presented in this publication do not reflect presentation of diverse opinions and positions by scientists worldwide, regardless of their race, includes a reference to the article's full citation. GSA provides this and other forums for the the abstracts only of their articles on their own or their organization's Web site providing the posting to further education and science. This file may not be posted to any Web site, but authors may post works and to make unlimited copies of items in GSA's journals for noncommercial use in classrooms requests to GSA, to use a single figure, a single table, and/or a brief paragraph of text in subsequent their employment. Individual scientists are hereby granted permission, without fees or further

Journal of Geodynamics, 2003

The earthquake distribution pattern of Central Europe differs systematically from the neighbouring areas of NW and southern Europe regarding the fault plane kinematics. Within a belt between the French Massif Central and the northern part of the Bohemian Massif (1000 km) sinistral faulting along N-S zones dominates on the contrary to the Alps and their foreland with common bookshelf shears. One of the prominent N-S structures is the Regensburg-Leipzig-Rostock Zone (A) with several epicentral areas, where the main seismic center occurs in the northern Cheb Basin (NW Bohemia). The study demonstrates new structural results for the swarm-quake region in NW-Bohemia, especially for the Novy´Kostel area in the Cheb Basin. There the N-S-trending newly found Pocˇatky-Plesna´zone (PPZ) is identical with the main earthquake line. The PPZ is connected with a mofette line between Hartusˇov and Bubla´k with evidence for CO 2 degassing from the subcrustal mantle. The morphologically more prominent Maria´nske´La´zneˇfault (MLF) intersects the PPZ obliquely under an acuate angle. In the past the MLF was supposed to be the tectonic structure connected with the epicentral area of Novy´Kostel. But evidence from the relocated hypocentres along the PPZ (at 7-12 kms depth) indicate that the MLF is seismically non-active. Asymmetric drainage patterns of the Cheb Basin are caused by fault related movement along Palaeozoic basement faults which initiate a deformation of the cover (Upper Pliocene to Holocene basin filling). The PPZ forms an escarpment in Pliocene and Pleistocene soft rock and is supposingly acting as an earthquake zone since late Pleistocene time. The uppermost Pleistocene of 0.12-0.01 Ma deposited only in front of the fault scarp dates the fault activity. The crossing faults envelope crustal wedges under different local stress conditions. Their intersection line forms a zone beginning at the surface near Novy´Kostel, dipping south with increasing depth, probably down to about 12 km. The intersection zone represents a crustal anomaly. There fault movements can be blocked up and peculiar stress condition influence the behaviour of the adjacent crust. An ENE-WNW striking dextral wrench fault was detected which is to expect as kinematic counterpart to the ca. N-S striking sinistral shear zones. Nearly E-W striking fracture segments were formerly only known as remote sensing lineaments or as joint density zones. The ENE shear zone is characterized by a set of compressional m-scale folds and dm-scale faults scattered within a 20 m wide wrench

Eos, Transactions American Geophysical Union, 1981

Tectonophysics, 2003

The Roer Valley Rift System (RVRS) is located between the West European rift and the North Sea rift system. During the Cenozoic, the RVRS was characterized by several periods of subsidence and inversion, which are linked to the evolution of the adjacent rift systems. Combination of subsidence analysis and results from the analysis of thickness distributions and fault systems allows the determination of the Cenozoic evolution and quantification of the subsidence. During the Early Paleocene, the RVRS was inverted (Laramide phase). The backstripping method shows that the RVRS was subsequently mainly affected by two periods of subsidence, during the Late Paleocene and the Oligocene–Quaternary time intervals, separated by an inversion phase during the Late Eocene. During the Oligocene and Miocene periods, the thickness of the sediments and the distribution of the active faults reveal a radical rotation of the direction of extension by about 70–80° (counter clockwise). Integration of these results at a European scale indicates that the Late Paleocene subsidence was related to the evolution of the North Sea basins, whereas the Oligocene–Quaternary subsidence is connected to the West European rift evolution. The distribution of the inverted provinces also shows that the Early Paleocene inversion (Laramide phase) has affected the whole European crust, whereas the Late Eocene inversion was restricted to the southern North Sea basins and the Channel area. Finally, comparison of these deformations in the European crust with the evolution of the Alpine chain suggests that the formation of the Alps has controlled the evolution of the European crust since the beginning of the Cenozoic.

Basin Research

We performed a detailed analysis of the thermal state of the Cenozoic Roer Valley Graben, the northŵ estern branch of the European Cenozoic Rift System, based on a new set of temperature data.We developed a numerical technique for correcting bottom hole temperatures, including an evaluation of the uncertainty of thermal parameters. Comparison with drill stem test temperatures indicated that the uncertainty in corrected bottom hole temperatures using a two -component numerical model is approximately AE 4 1C, which is much more accurate than the up to15 1C errors encountered in oftenused line-source or Horner correction methods.The subsurface temperatures and the derived regional heat £ow estimates of 53 AE 6 to 63 AE 6 mWm À 2 show no signi¢cant di¡erence between the central rift and the adjacent structural highs.The absence of an elevated heat £ow is attributed to the low amount of lithospheric thinning during the Cenozoic rifting phase (b 5 1.06^1.15). A local thermal anomaly exceeding 110 1C was found in ¢ve wells in the north^western part of the rift basin at depths of 1000^1500 m, and is most likely caused by the upward £ow of £uids along faults, whereas lower temperatures in the upper1500 m in the southern part of the rift basin could indicate cooling by topography-driven groundwater £ow. Con£icting ideas exist on the active or passive rifting mechanisms responsible for the formation of the di¡erent rift basins of European Cenozoic Rift System.The low spatial variation in heat £ow found in this study suggests that the mechanism responsible for forming the Roer Valley Graben is passive rifting.