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Abstract

The profile 9N was recorded in 1988 as part of the DEKORP project, the German deep seismic reflection program. The seismic survey of the ca. 92-km long line 9N was conducted to investigate the deep crustal structure of the northern Upper Rhine Graben with high-fold near-vertical incidence vibroseis acquisition. The objectives of the survey were to delineate the geometry of the major faults, which control the graben subsidence, to map the geometry of deep crustal reflection patterns and to reveal variations of the seismic signature of the lower crust in the context of rift formation. The first results were discussed by Wenzel et al. (1991), summarized by Brun et al. (1992) and supplemented by many other researches. Since the Eocene the Upper Rhine Graben has represented an active rift system. It obliquely intersects the Saxothuringian and the Moldanubian domains, which are separated by the NW vergent and dextrally sheared Lalaye‐Lubine‐Baden‐Baden fault. In the northern Vosges and Black Forest massifs the shear zone is characterized by low-grade Devonian metasediments. The profile starts in the crystalline Odenwald in the east, intersects the Tertiary and Quaternary fill of the Rhine Graben and ends in the late Palaeozoic sequences of the Saar-Nahe Basin in the west, where it crosses the Permian rhyolitic Donnersberg intrusion. The profile 1C creates a continuation of the survey to the west. The seismic section of 9N shows different crustal structures on both sides of the graben and some indications of dipping reflections in the mantle on the western side, which could refer to the genesis of the Upper Rhine Graben.