Iberia Versus Europe--Effects of Continental Break-Up and Round-Up on Hydrocarbon Habitat

Robert Bourrouilh, Greg Zolnai

Based on the continuity of foldbelts and the positions of intermountain continental nuclei and transcontinental megashears, a close "Pangea fit" is proposed for the central and north Atlantic borderlands. The Variscan arch segment missing between Brittany and Galicia in the Gulf of Gascony (Biscaye) can tentatively be identified with the Flemish Cap block off Newfoundland. At the same time the northwest African-Gondwana border (central Morocco) was located some 800 km farther to the west-northwest, as compared to its present position in southwestern Europe (Iberia).

During the opening of the central and northern segments of the Atlantic Ocean (Jurassic and Cretaceous) and during the closure of the western Mediterranean basin, i.e., the thrust of Africa toward southern Europe (Tertiary), the European continental mass underwent deformation in the transtensive and transpressive modes, which reactivated parts of its inherited structural network. The "trailing" south European continental margin was partially dismembered into loosely bound continental blocks, to be assembled again during the subsequent Alpine orogenic cycle. These events can be compared with processes known in the northernmost and western segments of the North American continent.

Mechanisms are proposed for the formation and deformation of inter-and intraplate basins by way of moderate shifts (wrenching) and slight rotations, the direction of which changed during the Mesozoic-Tertiary according to the global stress field.

The above evolution and mechanisms had multiple and decisive effects on hydrocarbon generation, habitat, and accumulation.

AAPG Search and Discovery Article #91032©1988 Mediterranean Basins Conference and Exhibition, Nice, France, 25-28 September 1988.