--> Abstract: Reconstruction of Tethys from Permian to Recent: Implications for Sedimentary Facies Distribution and Oceanic Circulation, by J. Dercourt, N. Cotiereau, and B. Vrielynsk; #90987 (1993).

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DERCOURT, JEAN, NICOLAS COTIEREAU, and BRUNO VRIELYNCK, Universite P & M Curie, Paris, France

ABSTRACT: Reconstruction of Tethys from Permian to Recent: Implications for Sedimentary Facies Distribution and Oceanic Circulation

Restoring the various alpine orogens in the Tethyan belt from the Caribbean to Indonesia and integrating the kinematics (Ricou, 1992) in a global framework (Scotese et al., Paleomap, 1992), enables the various paleogeographical reconstructions to be assigned their correct latitudes.

A sequence of 14 maps is established at the 1:20,000,000 scale; the facies are represented on each map and assigned to 12 paleoenvironmental domains (Dercourt et al., 1992). An examination of these maps supports 5 main conclusions:

(1) Tethys has always been a discontinuous seaway; since the beginning of oceanic accretion, in early Jurassic time "seuils" existed (i.e. cratonic sediments, thinned crust and narrow oceanic strips bridging both sides of an ocean). On the seuils water is shallow. Three of them developed in (1) Caribbean, (2) Mediterranean, (3) Indonesian. On the seuils specific facies accumulates (e.g. ammonitico rosso).

(2) Tethyan latitudinal location controls the solar energy received and the major paleoenvironments (e.g. platform carbonates). Clastic influx is a second order parameter; it can mask the climatic carbonate regime but as soon as it disappears or weakens, the carbonates prevail again (e.g. northern margin of the Tethys).

(3) The hydrodynamics of the Tethys can be mapped once parameters such as bathymetry have been established. A preliminary map of Tithonian circulations has been settled (Cottereau, 1992) which shows the sense, direction and intensity of oceanic currents, amongst them upwellings which are of crucial importance for organic deposits (hydrocarbons, phosphates).

(4) Specific facies and concentrations are directly linked to lithospheric evolution (Hydrocarbons, Phosphates, Bauxite, Gold...).

(5) Some planktonic organisms, short lived species, can concentrate minerals which during bloom crises create huge quantities of oozes. Four main crises have been detected (Busson and Noel, 1991). The location of pelagic deposits are directly correlated with paleogeography and paleocirculations.

References: Ricou, 1992, Plate-kinematics of Tethys, in prep.; Dercourt, Ricou and Vrielynck, Paleoenvironment Atlas of the Tethys, in prep.; Scotese et al., this meeting; Cottereau, 1992, UPMC, Thesis; Busson and Noel, 1991, CRACSC (Paris), II.

AAPG Search and Discovery Article #90987©1993 AAPG Annual Convention, New Orleans, Louisiana, April 25-28, 1993.