Triassic deposits are not widespread in Afghanistan but are known from isolated outcrops in northern Afghanistan from the Pamir frontier in the east to the Iranian frontier in the west. In southern Afghanistan they can be traced from Jalalabad to Kandahar, along the southern slopes of the Hindu Kush and the Paro-Pamisus Range.

Three structural-statigraphic provinces involving Triassic rocks may conveniently be recognized: a north Afghan province with a great thickness of terrigenous sediments; a central province with a volcanic-terrigenous regime and a south Afghan province with an essentially carbonate sequence.

East of the north Afghan province are the Badakhshan and Nouristan zones. In the Badakhshan zone the lower and middle parts of the Triassic are composed of conglomerates and sandstones, while the upper part consists of a thick sequence of limestones, flysch-type sandy argillites and marl-argillite alternations. The Triassic sequence from the Nouristan zone is similar in lithology but has less total thickness. In view of the scarcity of diagnostic fossils the correlation of these rocks with those of the Central Pamirs is essentially a lithostratigraphic one.

Ladinian deposits are exposed in central and western parts of the north Afghan province in the Bandi-Turkestan area. Thick flysch-like sandstones and argillites, with interbedded coal layers and lenses, occur along the northern and western perimeter of the region and contain typical Ladinian fossils in their lower part. Above lie beds containing Karnian Halobia and ammonites, while the upper part of the sequence yields bivalves and ammonites of Norian aspect. Northwestwards, the deposits of the north Afghan province can be traced to the Mangishlak Peninsula and westwards to the vicinity of Meshkhed in Iran.

In the central Afghan zone, typical deposits from this region have been described from the area of Doab. In the lower part of the sequence volcanic strata are intercalated with limestone, conglomerate and sandstone beds. The thickness of the volcanic beds increases to over 2,000 m (approximately 6,560 ft) north of Doab, and these beds are overlain by Middle Triassic conglomerates, sandstones and shales with concretions. Fossils include representatives of the genera Progonoceras, Monophyllites, Ceratites, Daonella and Entolium. The overlying flysch-like deposits totalling over 1,000 m (approximately 3,280 ft) in thickness are correlated with the Upper Triassic sequence of the Bandi-Turkestan areas. Their Karnian-Norian age is confirmed by the presence of the bivalves Halobia and Monotis salinaria. Volcanic rocks with interbedded sediments containing Rhaetian Baiera and Rhaetian-Liassic spores and pollen complete the succession.

The thickest Triassic sequence totalling over 6,000 m (approximately 19,680 ft), has been described by Mikhailov and others from the western part of the central zone, north-east of Herat. Lower Triassic limestones, siltstones and sandstones, with species of Eumorphotis, Myophoria, Naticella, Kashmirites and Tirolites, overlie volcanic rocks, while Middle Triassic

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limestones, sandstones and argillites with Sturia sunsovini and Karnian-Norian conglomerates complete the sequence.

The south Afghan province includes two regions: an eastern one (Kabul-Jalalabad) and a western one (Helmand). In the eastern region the Triassic is represented by an almost continuous carbonate sequence. The Lower Triassic strata consist of red and grey limestones with interbedded siltstones. Kemel has described a rich ammonite fauna from the Lower Triassic, enabling the Owenitan and Subcolumbitan zones of the Olenekian Stage to be recognized. Middle Triassic limestones contain Beyrichites, Discoptychites and other fossils in the Kabul area and Japonites near Jalalabad. Upper Triassic limestones and dolomites have yielded the coral Procyclolites, as well as megalodont remains.

In the western part of the south Afghan province ammonites are absent from the Lower Triassic limestones, but the bivalves Claraia aurita, C. orbicularis and Eumorphotis are abundantly represented. The Middle Triassic in this region comprises dolomitic limestones, the Upper Triassic thick megalodontid-rich limestones.

The presence of an essentially continental facies in the north Afghan province during Late Permian and Early Triassic times testifies to the absence of marine basins in the area. A marine transgression began no earlier than the Olenekian in this northern region. In southern Afghanistan, however, Triassic carbonates overlie Upper Permian carbonates without tectonic unconformity, although detailed studies indicate a slight hiatus in the stratigraphic succession. The absence of the earliest Triassic faunal zones here also indicates a time break.

Triassic sequences in the north Afghan province may be correlated eastwards with analogous deposits in the Central Pamirs. There is also a similar sequence in southern Mangishlak, the eastern coast of the Sea of Azov and the mountainous parts of the Crimea. The south Afghan Triassic sequence also has much in common with that of Armenia and Nakhichevan.

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