Petrological Study of Chilou Formation In Al Hole Field –syria

Abstract

The Chilou Formation is spread in the East and Northeastern part of Syria. In the study area (Al-Hole field) it’s adjacent to the Iraqi border from the east, 50 km from the Al-Hasaka city to the east and 65 km south of Qamishli city. From the tectonic point of view, the study area belongs to the Sinjar-Abdul-Aziz belt unit. The Chilou formation was divided based on index Fossils content with help of well logs into two lithostratographic members, under them a series of lithological units. The lower member dates back to the age of Oligocene, It’s predominantly composed of: limestone, Argillaceous Limestone, Marl, Shale facies. While, the Upper member dates back to the age of the lower Miocene, it’s composed of: limestone, Argillaceous Limestone, Marl, Shale, salt facies and Anhydrite sometimes tinged with gypsum. The facies are rich in planktonic (Lower member) and pelagic foraminifera (Upper member) with deposits of pyrite, gluconate and fissured. The anhydrite is a clear boundary between the members. The formation sediments were subjected to diagenesis phenomenon, including partial and total pyritic processes of some fossil frameworks and dissolution, filling processes – dissolution processes that led to create a stylolite structures. It represents a deep sea facies (Lower member) which turns upward into a lagoon facies as a result of

marine regression (Upper member).