Tethys Ocean

Abstract: Kinematic Section: The Plate Tectonic History of the Past Tethys Ocean (L.E. Ricou). Apparent Polar Wandering Paths for North America, Europe, Africa, Laurussia, and West Gondwana Since the Upper Carboniferous: A Review (J. Besse et al.). New Geologic Data: Late Carboniferous to Recent Geodynamic Evolution of the West Gondwanian Cratonic Tethyan Margins (R. Guiraud, Y. Bellion). Crustalscale, Thrust Complex in the Rhodope Massif: Evidence from Structures and Fabrics (J.P. Burg et al.). Paleogeographic Reconstructions: Late Permian to Late Triassic Tethyan Paleoenvironments (J. Marcoux, A. Baud). Synthetic View: Tethyan Carbonate Platforms (J. Philip et al.). Radiolarians and Tethyan Radiolarites from Primary Production to Their Paleogeography (P. De Wever et al.). Paleoenvironments and Organicrich Facies Deposition in the Tethyan Realm: Toarcian, Kimmeridgian and Cenomanian Time Intervals (F. Baudin, J.P. Herbin). Geodynamics of Bauxites in the Tethyan Realm (P.J. Combes, G. Bardossy). Tethyan Phosphates and Bioproductites (J. Lucas, L. PrevotLucas). From Tethys to Panthalassa: The Role of Tethys in the Evolution of the Northern Andes between Late Permian and Late Eocene Times (E. Jaillard et al.). Conclusions: The Tethys: An Ocean Broken by Seuils Lithospherique (B. Vrielynck et al.). 4 additional articles. Index.

Abstract: Some considerations on the palaeogeography of the Mediterranean and Paratethys Oligocene to Miocene are presented in ten time-slices. The time-slices start with the vanishing Tethys Ocean in the late Eocene and the birth of two new marine realms at its western end: the Mediterranean Sea and the intercontinental Eurasian Paratethys basin. The time-slices were selected according to general palaeogeographic changes of seaways and arising land bridges for continental migrations. The palaeogeographic sketches were based on Cenozoic plate reconstructions, and the intermediate levels are interpolated accordingly. Strong changes occurred in the history of the Paratethys. From an open ocean in the Eocene with connections to the Polar Sea via the Turgai Strait, it changed to an enclosed basin in the early Oligocene with reduced salinity and endemic faunas. From the middle Oligocene on, the basin opened again, reaching a maximum connection with the Indian Ocean during late Oligocene and early Miocene (late Chattian ‐ early Burdigalian). Intermittent seaways and regional close-off of basins with endemic development characterize the late Burdigalian and middle Miocene. By the mid-Serravallian the final disconnection of the Paratethys occurred, and since Sarmatian time reduced salinity conditions and endemisms prevailed. The Mediterranean was the connecting sea between Indo-Pacific and Atlantic Oceans until the late Burdigalian. With the collision of the Arabian and Anatolian plates in the late Burdigalian, an Eurasian ‐ African landbridge opened for mammal migrations. A short interruption is proposed for the Langhian transgression, followed by a final closure in the Serravallian.

Abstract: The post-Hercynian sequence of the Middle East is dominated by carbonate sedimentation on a stable platform flanked on the northeast by the Tethys ocean. Two principal types of depositional systems alternated in time: (1) ramp-type mixed carbonate-clastic units and (2) differentiated carbonate shelves. The first type was deposited during regressive conditions, when clastics were brought into the basin and resulted in "layer-cake" formations. The second type was formed during transgressive periods and is dominated by carbonate cycles separated by lithoclines, time-transgressive submarine lithified surfaces. Differentiation is marked, with starved euxinic basins separated by high-energy margins from carbonate-evaporite platforms. The tectonic development of the Middle East can be divided into several stages. The first stage, which ended with the Turonian, was characterized by very stable platform conditions. Three types of positive elements were dominant: (1) broad regional paleohighs, (2) horsts and tilted fault blocks trending NNE-SSW, and (3) salt domes. All three influenced deposition through synsedimentary growth. The subsequent stage, from Turonian to Maestrichtian, was one of orogenic activity, with the formation of a foredeep along the Tethys margin and subsequent ophiolite-radiolarite nappe emplacement. From the Late Cretaceous to the Miocene the platform regained its stability, only to lose it again at the close of the Tertiary, when the last Alpine orogenic phase affected the region, creating the Za ros anticlinal traps. Source rocks were formed in the starved basins during the transgressive periods. Marginal mounds, rudist banks, oolite bars and sheets, and regressive sandstones form the main reservoirs. Supratidal evaporites and regressive shales are the regional seals. The spatial arrangement of these elements and the development of source maturity through time explain the observed distribution of the oil and gas fields.