The Eocene – Oligocene Facieses and Sedimentary Environments in Sardarreh Area, Garmsar

Abstract

This research studies the Eocene – Oligocene facieses and sedimentary environments have in Sardarreh, Garmsar. Field studies were conducted to achieve this goal. So, 95 samples were taken from the studied section. Because of the similarity of the samples, 49 samples were selected for the preparation of thin sections. For facies interpretation and providing sedimentary model (Carruzi, 1989((Flugel, 2011) and naming of carbonate rocks (Dunham, 1962)، (Folk, 1962) and (Chen, 2011) were used. Thin section consists of: skeletal elements, including(Mollusks, Brakiopoda, Akinoderma, Foraminifera, Algae, Ostracoda, Gastropods) and Non-skeletal particles(pelloidy, intra-clast), Quartz(grains of sand), Gloconite, Feldspar,  Chert, Gypsum, Salt, Anhydrite and facies’s matrix are calcareous mud and micritic or Asparitic cement. These studies led to the identification and separation of 7carbonate and destruction facies that have deposited in 4 facies belt. Open marine facies includes: A1: Bio-clast pack stone. Barrier facies takes in: B1: Pelloid bio-clast grain stone. Pool facies holds: C1: Gypsi- ferrous marl, C2: Calcareous sandstone.Tidal facies zone comprises: D1: Sandy pelloid wack stone / pack stone, D2: Sandy intra-clast wack stone / pack stone and D3: Fenestral mudstone. Due to interpretation of these facieses and their environments, the ancient geographical situation of this area is characterized. This is a carbonate platform which is a kind of carbonate Rimmed shelf.