Geochemical studies to characterize the amount, origin, and petroleum potential of organic matter in Toarcian rocks have been performed on samples from outcrops and cores within the Mediterranean area and the Middle East. Maps were prepared to show the concentration and nature of organic matter during Toarcian time. These maps show great heterogeneity in the quantity and type of organic matter: (1) marine planktonic material deposited in reducing environments in shallow-water basins in northwestern Europe, or in deep basins in the Tethys; (2) terrestrial organic matter from higher plants, that is moderately degraded along the northern Tethyan margin and in the northern North Sea; and (3) residual or oxidized organic matter that occurs in most of the Tethys basins. These d ta show the existence of several environments where organic matter was preserved during the Toarcian anoxic event.

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