Results of Geochemical Analysis of Seeps and Potential Source Rocks from Northern Turkey and the Turkish Black Sea
A. Sami Derman, Y. Haluk İztan, 1997. "Results of Geochemical Analysis of Seeps and Potential Source Rocks from Northern Turkey and the Turkish Black Sea", Regional and Petroleum Geology of the Black Sea and Surrounding Region, A. G. Robinson
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Hydrocarbon shows have been known in northern Turkey for more than 100 years. Close to the Black Sea, several source rock units, mainly from outcrops but also from wells, have been tested for source rock potential. Organic geochemical studies on subsurface and surface samples indicate that there are several potential hydrocarbon source rock units in the region: the Kartal Formation (Early Devonian), Yilanli Formation (Middle Devonian–Early Carboniferous), Alacaagzi and Zonguldak Formations (Carboniferous), Himmetpaga Formation (Middle Jurassic), (Çağlayan and Ülüs Formations (Cretaceous), Yemişliçay Formation (Late Cretaceous) and Kusuri Formation (Eocene). The Zonguldak and Himmetpaga formations are composed of predominantly gas-prone vitrinite macerals. The coal samples from the Alacaağzi Formation have a different maceral composition consisting predominantly of sporinite, which is capable of producing oil. Four surface oil seeps, one seep from offshore of Rize, one oil show from İğneada-1 well, one gas seep from the Ülüs Basin, and one gas sample from the Akçakoca-1 well, have been analyzed using classical organic geochemical techniques (pyrolysis, gas chromatography, and gas chromatography-mass spectrometry). An attempt has been made to correlate possible source rock in the area with the Armutçuk oil seep. Results of geochemical analysis of the oil seeps from different localities in the Black Sea region indicate that they have been derived from different units.
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Regional and Petroleum Geology of the Black Sea and Surrounding Region
In 1967 and 1969, two oceanographic cruises were made in the Black Sea under the guidance of the Woods Hole Oceanographic Institute: The cruises included scientists from many countries and disciplines. Their aims were to determine the recent geological and geochemical evolution of the Black Sea, to map the shallow structure of the basin, and to study the interaction between the oxidized surface waters and the anoxic waters beneath them. The results were published 23 years ago, as AAPG Memoir 20 (Ross and Degens, 1974). During the 1969 cruise, the vessel Atlantis II collected 40 piston cores, which formed the basis of most of the subsequent geological studies that were restricted to very recent sedimentation. Speculations concerning the origin of the basin and the relationship of the geology offshore to that exposed around the margins of the Black Sea were rooted in pre-plate tectonic concepts of basin formation and were in any case hampered by a lack of relevant data (Brinkmann, 1974).
In 1976, the Glomar Challenger visited the Black Sea on Leg 42B of the Deep Sea Drilling Project and drilled and cored three deep-water sites (379, 380, and 381). Well 381 north of the Bosporus encountered sediments as old as Miocene, including some apparently deposited in shallow water (Ross, 1978).
The next major volume in Western literature to deal with the Black Sea was published a decade later, collecting papers presented two years earlier at a conference in Yalta. In this volume, a number of seismic reflection lines