The geology of Afghanistan is described in relation to hydrocarbon occurrence and future potential. Current gas production, exported to Russia, is abstracted from structural closures in Cretaceous — Neogene sediments on the margin of a Neogene — Recent depression northwest of the Hindu Kush mountain range. Source rocks are thought to be Jurassic paralic sediments and/or Cretaceous platform limestones, the latter outcropping extensively across much of central Afghanistan north of the Herat fault zone, a major fracture separating two tectonically different regions. Future exploration should be directed towards the search for similar structural closures with other Neogene — Recent depressions bordering the Hindu Kush, particularly in the north and west.

Substantial thicknesses of Mesozok and Paieogene clastic and calcareous successions are reported to occur in the southern part of the Katawaz fault block, a geotectonic unit between two major fracture zones in SE Afghanistan. Aeromagnetic and field studies indicate a basin up to 9000m thick containing suitable source and reservoir rocks but tight folding, lack of seal lithologies and excessive depth of erosion lessen the chances of finding hydrocarbon pay zones.

Future discoveries are more likely to be gas than oil as the geothermal gradient, both present and historis is thought to be high in view of the tectonic position within a collision zone. Nevertheless, oil seeps, bitumen and fetid limestone in central and western Afghanistan suggest dissociation may not be complete.

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