The "Hercynian" Disturbance in Arabia and North Africa

By

 Saad Z Jassim¹, Ian W Somerton¹

(1) GETECH, Leeds, West Yorkshire, United Kingdom

 Analysis of gravity and magnetic data and over 1600 wells from Arabia and North Africa suggest that the "Hercynian" collision of the Mauritanids was simultaneously associated with a massive mantle plume that affected most parts of Africa and Arabia during the Permocarboniferous. The plume(s) resulted in a series of N-S arches during the Early Carboniferous. Some of these arches were associated with extensions in the Early Permian. Volcanicity is known only from the Karoo system of S and E Africa and from the margins of Arabia. At the Indian Ocean-Arabian Sea-Zagros triple junction, SE of Oman, Alpine-type Gondwanan glaciation affected southern Arabia. The "Hercynian" N-S arching resulted in the removal of a large thickness of Lower Paleozoic sequence, during both the Early Carboniferous, and Early Permian where extension did not follow arching, (for example in Jordan and the Tibesti region of Libya). On the other hand where extension did occur, during the Early Permian, fluvio-lacustrine clastics were laid down in narrow basins over L Paleozoic rocks, (in Central Arabia and E Algeria). The hydrocarbon systems related to the "Hercynian" disturbance are outlined.

The highly disturbed Mauritanids tectonic block seems to be in sharp contact with a virtually undisturbed tectonic block to its east, and it is thought that a dextral strike slip fault might be the culprit.