Organic facies variation from well data on the Cudi Group, the eastern part of SE Turkey

Abstract

South Turkey is situated on the transition zonebetween the Arabian–African plate and Alpine–Hima-layan orogenic belt. The eastern segment of South Tur-key is located at the northern margin of the Arabianplate (Fig. 1). This is the only tectonostratigraphic unitin Turkey where significant petroleum production istaking place. The region includes rock units, ranging inage from Cambrian to Miocene Derik, and HaburGroup strata are the basement of the autochthonousrock units of Southeast (SE) Turkey (Fig. 2).The Middle Triassic–Lower Jurassic Cudi Group(Figs. 2, 3) units are composed mainly of evaporiticdeposits in the west and marine carbonates in the eastpart of SE Turkey. During the detailed geological stud-ies, the geological structures and the tectonostrati-graphic relations that have developed at different geo-logical periods of the southeastern Anatolia are rela-tively well known and have been documented innumerous publications [1–16]. Also source rock poten-tial has been reported from several sedimentary unitswhich was deposited in the western and eastern part ofSE Turkey [17–34]. By contrast, only a few studieshave reported the organic facies in the Cudi Group. Inthis study, six geochemical logs from Cilesiz-1, B.Yolacan-1, G. Dincer-1, Camurlu-101, Camurlu-102, andYolacan-3 wells, which were drilled by the TurkishPetroleum Corporation in the same area, were used.The purpose of this work is to characterize the organicgeochemistry of the Middle Triassic to the LowerJurassic Cudi Group of the eastern part of SE Turkey, todetermine their kerogen type, and to assess theirorganic facies properties.Southeast Anatolia was situated in the southernhemisphere as a part of the Gondwanaland during thePaleozoic. The Arabian Plate and its northern edge (SEAnatolia) were affected by the epirogenic movementsof Caledonian and Hercynian orogenic events [35–38].All sediments were deposited on the continental shelf