Journal of Petroleum Geology, Vol.12, No.1, pp. 29-50, 1989

©Copyright 2000 Scientific Press, Ltd.

THE HEZAN UNITS: A FRAGMENT OF THE SOUTH NEO-TETHYAN PASSIVE CONTINENTAL MARGIN IN SE TURKEY

J.M. Fontaine (1), O. Monod (2), J. Braud (2), D. Perincek (3)

1. Direction Exploration, Elf ,4quitaine, Tour Elf, 92078 Paris la Défense Cedex 45, France.

2. Université Paris-Sud, Lab. de Géologie Historique. Bâtiment 504, 91405 Orsay Cedex, France.

3. TPAO, Arama Grubu, 22 Mudafaa Cad., Bakanliklar, Ankara, Turkey.

Abstract

Recent progress in structural and stratigraphic analysis of the allochthonous units situated north of Hazro in the Border Fold zone of SE Turkey has shed light on the nature and significance of the Gondwanan margin there. Allochthonous material consists of several superimposed units ranging in age from the Early Trias to the Late Senonian (Hezan units), in which the transition between neritic carbonates and the pelagic and detrital facies is well indicated by an Ammonitico-rosso facies of mid Jurassic age. Above it, ophiolitic material and radiolarites represent the former Tethyan crust and cover. The Hezan units thus belong to the former Gondwanan margin thrust southwards in Late Cretaceous times, and a tentative reconstruction of its Mesozoic evolution there is facilitated by the absence of later major tectonic events.