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As a result of early Variscan tectonic movements and of differential subsidence, a platform and basin topography was created along the northern margin of the Sahara Craton during the late Devonian. In the Moroccan Anti-Atlas Mountains, the Tafilalt Platform is an approximately N-S running ridge which developed since the late Middle Devonian. It separated a slowly subsiding shallow basin in the east (Tafilalt Basin) from a rapidly subsiding furrow in the west (Mader Basin). Platform deposits are characterized by highly reduced thicknesses, shallow subtidal to supratidal deposits in the late Frasnian and by unconformities at the Lower/Upper Frasnian and the Frasnian/Famennian boundaries. After a local transgression over emergent areas in the north, water depth probably never reached more than several tens to about 100 m in the lower Famennian. Cephalopod limestones of this age, deposited on the platform, represent a very diverse facies pattern comprising quartz-rich brachiopod coquinas, crinoidal limestones, thick-bedded cephalopod limestones and nodular limestones. Sedimentation rates ranged from 1 to 5 mm/ 1000 yr. In the late Famennian more uniform marl and nodular limestone facies suggest slightly deeper environments. Platform margins are characterized by higher rates of subsidence, debris flow deposits and slump structures. In the relatively shallow Tafilalt Basin, mark with intercalated nodular limestones were deposited. In the Mader Basin, sandy and calcareous turbidites suggest deeper water conditions in the late Devonian. During the Strunian/Tournaisian the whole area was overwhelmed by a thick deltaic sequence. The general facies distribution is in agreement with depositional models of other Upper Devonian and Lower Carboniferous cephalopod limestones in the European Variscan orogenic belts. In all these cases, condensed cephalopod limestones occupy a distinct palaeogeographic position in predictable facies sequences that reflect pre-orogenic phases in the Variscan geodynamic cycle. Moreover, close parallels exist with condensed sequences in the Triassic and Jurassic that occur in a very similar position within the Alpine orogenic cycle. R %. s. b 3 --

We present the Euler rotations of the plates involved in the Alpine–West Carpathian orogen. The rotations are defined to a large extent by the magnetic anomalies of the Atlantic Ocean. A few extra rotations occurred during two collisions and a Mid-Cretaceous event. At variance with earlier reconstructions, we additionally control the rotations by the orientation of palaeomagnetic declinations. The plate rotations are integrated into a model illustrated by palaeogeographical maps. Special features of the model are: (1) subdivision of the northern margin of Adria into the two plates, Pelso and Austroalpine–West Carpathia, on the basis of palaeomagnetic data; (2) Eohellenic obduction of Meliata units onto the eastern margins of Pelso and Austroalpine–West Carpathia from the Tethys side; (3) first (Eoalpine) collision of the marginal plates of Adria with Tisza far off the West European plate margin; (4) a 80–90° rotation of Austroalpine–West Carpathia during the Eoalpine collision; (5) subdivision of the Neoalpine collision into a Palaeogene stage of predominantly strong SE–NW shortening and a Neogene stage of predominantly lateral extrusion westward and eastward. In principle, the maps show quantitative ocean spreading, subduction, and plate rotations. However, possible modifications of the model discussed in this paper limit the quantitative evaluation.

The course of the active North Anatolian Fault system from Lake Abant to Lake Sapanca was traced by its high micro-earthquake activity. If approaching from the east this section includes a broad south to north overstep (fault offset) of the main fault.Local seismicity has been recorded in this area by a semi-permanent network of 8 stations since 1985 within the frame of the Turkish-German Joint Project for Earthquake Research. The effect of the overstep and its complex fracture kinematics are reflected by the seismicity distribution, the variations of composite fault-plane solutions, and by the spatial coda-Q distribution. Areas of different stress orientation can be distinguished and assigned to different groups of faults.The stresses and the tectonic pattern only in part correspond to a simple model of an extensional overstep and its correlative pull-apart basin. Other types of deformation involved are characterized by normal faulting on faults parallel to the general course of the main strike-slip fault and by synthetic strike-slip faults oriented similar to Riedel shears. Shear deformation by this fault group widely distributed in an area north and east of the main fault line may play an important role in the evolution of the overstep. The development of a pull-apart basin is inhibited along the eastern half of the overstep and compatibility of both strands of the main fault (Bolu-Lake Abant and Lake SapancaIzmit-Marmara Sea) seems to be achieved with the aid of the fault systems mentioned. The extension of the missing part of the pull-apart basin seems to be displaced to positions remote from the Lake Abant-Lake Sapanca main fault line, i.e. to the Akyazı-Du¨zce basin tract.Highest Q-values (lowest attenuation of seismic waves) were found in the zone of highest seismicity north and west of the overstep which is the zone of strongest horizontal tension. If high coda-Q is an indicator for strong scattering of seismic waves it might be related to extensional opening of fractures.

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