Writers : Ghavidel- Syooki,M.
Refference : Geosciences Scientific Quarterly Journal,No.:15-16,P.:74
Publishing Year : 1374

Abstract :
The Paleozoic sequence has an outcrop at Kuh-e- Gahkum. The sequence has been sub- divided in ascending order into the Barut Formation, Silurian Shales, Faraghan and Dalan Formations (Szabo and Kheradpir, 1978). So far the Silurian deposits have been used to be called as "Silurian Shales'. In this study, the use of "Silurian Shales" is dropped and the Sarchahan Formation is introduced for the Silurian sediments in the Zagros basin. The name of Sarchahan Formation originates from the Sarchahan village where is located approximately 120 Km northern Bandar Abbas city. The type section of Sarchahan Formation is at Tang-e-Abzagh of Kuh-e- Gahkum where is located, approximately 10km northern Sarchahan village. This Formation is well- developed and accessible at Kuh-e-Gahkum and Kuh-e-Faraghan as well. The Sarchahan Formation is 102m and 66m thick, respectively at Kuh-e-Gahkum and Kuh-e- Faraghan. Ukewise, this Formation is found with a thickness of 75m and 70m, respectively in exploration wells of Persian Gulf (G-3) and Zirreh No.1.
The Sarchahan Formation mainly consists of clastic sediments with subordinate limestone stringers.
The lowermost beds of the Sarchahan Formation comprise of buff calcareous conglomerates interbedded with dark- gray shales and sandstones. Overlying beds of these conglomerates change into olive- gray shales with thin- interbeds of limestones and sandstones. The lower contact of Sarchahan Formation is disconformable with the Barut Formation at Kuh-e-Gahkum and is graditional with the Seyahou Formation at Kuh-e-Faraghan. The upper contact of this formation is disconformable with the Faraghan Formation at both Kuh-e-Gahkum and Kuh-e- Faraghan. The Sarchahan Formation contains brachiopod, bryozoa, graptolite, acritarch and chitinozoan species. Therefore, it has been deposited in a shallow marine environment. Some graptolite species such as Monograptus intermedius, Manograptus socialis, and Chinacagraptus scalaris have been recorded from the Sarchahan Formation at Kuh-e- Faraghan (Kheradpir and Nicol, 1973). Based on the above- mentioned graptolites, the lower Silurian has been suggested for the Sarchahan Formation. Moreover, all samples of Sarchahan and Faraghan Formations at Kuh-e- Gahkum were treated and studied for palynomorph taxa. A total of 54 palynomorph taxa were encountered in this study (Fig.2). These have been arranged in six local ascending zones; the zones I and II appear in the Sarchahan Formation and are characterized by presence of Visbysphiaera !o,'ffera, Visbyszhaera microspincsa, Visbysphaera oligofurcata.
Subject List : Stratigraphy