پاليواكولوژي و پاليوبيوژيوگرافي اليگوسن بالايي ميوسين زيرين غرب اردستان براساس مطالعه فونهاي مرجاني

Paleoecology and Paleobiogeography of the Upper Oligocene-Lower Miocene Sediments Basd on Corals in West Ardestan

The study area is located 110 kms north, northeast of Isfahan and 20 kms west of Ardestan, behind the magmatic arc (Bazman-Uroomieh trend). Thick sequence (465 meters) of sediments equivalent to Qom formation overlain the Eocene volcanic rocks (andesite, trachyandesite and andesitbasalt). Lithologicaly the Qom formation comprises six members and four submembers. The thickness of the Qom Fromation is most increased around the city of Qom. The sediments in the study area (west Ardestan are not dividable into members. In this study numbers at corals are gathered, identified and introduced. Corals are from 150 meters above the base of the section and are used for paleoecology and paleobiogeo graphical considerations. The corals are mixtures of Indopacific and Mediteranian corals. Scattered solitary corals in some horizons reflect turbulence within environment and faviides and porites corals in some other horizons also confirm turbulence in Oligo-Miocene time in the study area. As a result, deposition of the above mentioned sediments took place under strong high energy, turbulent and shallow water depth of deposition.