Palaeoceanography and biogeography in the Early Jurassic Panthalassa and Tethys Oceans

A first conceptual palaeoceanographic model for the Early Jurassic Panthalassa and Tethys Oceans is outlined in the present paper. The new palaeoceanographic model uses fundamental physic–oceanographic principles known from the modern world and a global palaeogeographic reconstruction for the Early Jurassic to examine the long-term response of the Panthalassic and Tethyan fossil invertebrate faunas to the proposed surface ocean circulation. Analysis of palaeobiogeographical data (ostracods, ammonites, brachiopods and bivalves) has enabled circulation changes to be reconstructed over the studied period in some detail. Panthalassic circulation pattern shows an almost hemispherical symmetric pattern, with the development of the two large subtropical gyres that rotates clockwise in the northern hemisphere and anti-clockwise in the southern hemisphere. Surface circulation in the Tethyan Ocean is dominated by monsoonal westerly-directed equatorial surface currents that reached its western corner and droved them off to the north, along the northern side of the Tethys Ocean, during summer and in opposite direction during the winter.