Updated Geological Data from the Drilling of the NW Sabalan Geothermal Project, Iran

Abstract

Four deep exploration wells drilled in the Northwest Sabalan geothermal project encountered Quaternary terrace deposits and Pliocene andesite-trachyandesitic volcanics at the beginning. The most northerly of the wells continued into a sequence of Pliocene to Neogene volcanics before drilling down the dip of a sequence of Eocene volcanics and running along a disconformity with Paleozoic metalitharenite. Similar Eocene volcanics were encountered in the other wells, with the most southerly well penetrating a Miocene monzonite batholith and surrounding hornfels. Diorite porphyry dykes were found just in the two southern wells with the youngest known dykes being found in the most southerly well.
The alteration occurance through all well samples are believed to produced by hydrothermal events associated initially with the monzonite and the two phases of dyke intrusion rather than volcanics related hydrothermal systems. The more aboundant lithological data gathered by sample studies made a better understanding of Sabalan geothermal field geological concept and future exploration-production management of project.