Geology and Petroleum Potentials of Central and South Afghanistan

Abstract

Afghanistan is in a broad mobile belt extending mainly east-west between the old shield of Fennosarmatia in the north and Gondwana in the south. Four major geotectonic units separated by deep-seated fault systems can be recognized. These units are: (1) North Afghan-Tadjik unit, (2) East Iran-Central Afghan unit, (3) East Afghanistan-West Pakistan unit, and (4) marginal region of the Indian shield. In central and south Afghanistan the following blocks can be distinguished: in the East Iran-Central Afghan unit, the Farah, Helmand, and Seistan fault blocks; in the East Afghanistan-West Pakistan unit, the Nooristan fault block, and in the marginal region of the Indian shield, the Katawaz fault block. No prospects, or at best poor prospects, exist for the discovery of economically exploitable petroleum in the Farah, Helmand, Seistan, and Nooristan fault blocks. Petroleum possibilities are assumed to exist in the Katawaz fault block of southeastern Afghanistan. The Katawaz fault block is the only one in southern Afghanistan in which a maximum of 9,000 m (30,000 ft) of late Paleozoic, Mesozoic, and Paleogene sediments have been deposited on the basement. The facies are predominantly marine. Potential reservoir rocks probably are represented by clastic strata deposited at the Cretaceous-Tertiary transition and by sandstone intercalated in the Paleogene sequence. Good to excellent trapping conditions could exist in regularly folded anticlines of Oligocene age as much as 50 km (30 mi) long. Depositional wedges within the subsurface Mesozoic and Paleogene formations could be present. Seismic reconnaissance surveys would provide more precise data pertinent to the existence of favorable structures.