Kinematic evolution of the Tethys belt from the Atlantic ocean to the pamirs since the Triassic |
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| Authors: | Lonid A Savostin Jean-Claude Sibuet Lev P Zonenshain Xavier Le Pichon Marie-Jos Roulet |
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| Institution: | Léonid A. Savostin, Jean-Claude Sibuet, Lev P. Zonenshain, Xavier Le Pichon,Marie-José Roulet |
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| Abstract: | We present an updated series of kinematic reconstructions of the major plates around the Tethys from the Atlantic Ocean to the Pamirs between the Early Jurassic and the Present. This set is used elsewhere as a basis for paleogeographic maps of the entire region. The problems related to the positions of the continents in the Lower Triassic are also discussed. No direct analyses of magnetic anomalies and fracture zones in the Atlantic have been made. Rather, all available poles and rotations have been tested in order to eliminate or minimize possible kinematic errors. The reconstructions are shown for nine key geological periods which correspond to well recognized magnetic anomalies, except for the Jurassic-Cretaceous boundary and the Cretaceous-Tertiary boundary which correspond to interpolated positions. Paleolatitudes have been drawn using the study of Westphal et al. (1986). An attempt has been made to take into account the displacements caused by formation of the continental margins and basins by stretching. The resulting relative vector of motions along the northern boundary of the Tethys shows a significant change 80 m.y. ago. Left-lateral motion with compression dominates before whereas right-lateral motion with compression dominates after. To the east, rates of motion vary by a factor of three with time and four maxima can be clearly related to tectonic events in the Late Jurassic, Late Cretaceous, Eocene and post Middle Miocene. To the west, north of Apulia, on the contrary, the motion rate has not changed significantly since the Early Cretaceous and is close to 1 cm/yr as an average. These rather complex adjustments in rates and directions of relative motion are produced in great part through a complex migration of the Africa-Eurasia pole of rotation and seem to be mostly governed by the tectonics of the Tethys plate boundary. |
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