Publication Date:
2003-07-01
Description:
The Upper Rhine graben is a north-northeast–trending, small-displacement, crustal-scale rift of Tertiary age. Retrodeformation of its southeastern part demonstrates that it is a product of sinistral oblique rifting. Early extension was toward 80°. Later, the major stretching axis changed to a 60° direction. The modeling results suggest that the eastern Main Border fault developed first, and that faulting later propagated into the evolving graben interior. Considerable along-strike variations in heave, throw, and displacement are evident. Displacement partitioning causes warping of the rift floor with a 30–35-km wavelength. We consider this to be a characteristic of oblique rifting. Contact deformation of the wall rocks to the major faults may have caused widespread smaller scale faulting and brecciation and may be the location of later movements. Close spatial coincidence of the depth projections of some of the faults studied and the hypocenters of recent small earthquakes indicates continuing activity of the fault system. Apparently, three fault segments in the Freiburg area are currently active and may be an increased earthquake risk. Jan Behrmann is a structural geologist and head of the department at the Geologisches Institut, Universität Freiburg. He has a doctorate from the University of Oxford. His research interests are evolution of active plate margins (e.g., Chile, Lesser Antilles) and collisional mountain belts (Alps, Hercynian orogen). He has recently studied the kinematics and dynamics of continental (Rhine graben) and back-arc rifting (Woodlark basin). He also has professional experience in gold exploration.Oliver Herrmann received a Diploma in geology from the Universität Freiburg in 2002. His interests are in structural geology and geo-computing. He is an engineering geologist with Terrasond GmbH (Günzburg, Germany) and works on tunneling projects in southern Germany. Mathias Horstmann received a Diploma in geology from the Universität Freiburg in 2002. He is interested in hydrocarbon geology, reservoir modeling, and structural geology. He is currently a drilling service engineer for Schlumberger Drilling and Measurements. David Tanner is researcher at GeoForschungsZentrum Potsdam (Germany). He received a B.Sc. in geology from Liverpool University, an M.Sc. from Imperial College, London, and a doctorate from Universität Giessen, Germany. He has worked on deformation of high-grade metamorphics and problems of melt segregation and transfer, and now specializes in 3-D kinematic and physical modeling of complexly deformed terrains. Guillaume Bertrand is postdoctoral researcher at Geologisches Institut, Universität Freiburg. He graduated in geology from Université Pierre et Marie Curie, Paris, and completed a doctoral study at Ecole Normale Supérieure, Paris. His first postdoctoral research position was at the University of Houston. He has worked on the neotectonics and thermochronology of Burma, and now investigates the dynamics of the European rift system.
Print ISSN:
0149-1423
Electronic ISSN:
1943-2674
Topics:
Geosciences
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