Study on the Role of Shemshak Formation in Creation of Some Geothermal Resources in Iran

Abstract

It is very clear that one of the important parts of a geothermal system is cap rock which covers reservoir properly. In fact, cap rock doesn’t allow geothermal fluid to escape from the reservoir. During implementation of some geothermal resource assessment projects in Iran it is found that there is a close relationship between some geothermal resources and Shemshak Formation outcrops. More studies revealed that Shemshak Formation is the cap rock of determined geothermal resources around Damāvand volcano, Rāmsar, Mahallāt and Ābegarm cities and Nāyband village. These geothermal systems have different geological characteristics but common cap rock. This Formation’s thickness is 1027 m and consisted of shale, sandstone, siltstone and claystone. Geographically it is outcropped in the Northern, Central and Eastern sections of the country and had been formed during lower Jurassic. Due to the suitable lithology and sufficient thickness of Shemshak Formation it is a unique cap rock for those geothermal reserves which have been formed in the above-mentioned parts of Iran. So, it might be a clue for determining of new geothermal reserves in other regions of Iran.