Organic Facies Characteristics in the Paleocene Shale of the Northern Part of the Tuz Go¨lu¨Basin, Central Anatolia, Turkey

Abstract

Paleocene sequence in the Tuz GölüBasin displays a range of lithofacies that vary greatly in thickness. The Paleocene units are made up of sandstone, conglomerate, shale, and limestone. Organic-rich intervals are present in the Paleocene of marine shale with 0.02-1.88 wt% organic carbon content. Pyrolysis yields (S1 + S2 = 80-10100 ppm) indicate that some intervals within the Paleocene shale have weak to good gas potential. It contains type III organic matter based upon Rock- Eval pyrolysis assay. Both organic petrographic and geochemical parameters place the Paleocene shale of the Tuz GölüBasin within the CD and D or C organic facies of Jones (1987). The lower sulphur content (< 0.08%) in the Paleocene units point to normal marine depositional conditions. Maturity is high in the lower Paleocene units where Tmax values are above 465°C. Most of the Upper Paleocene rocks are thermally immature to marginally mature with Tmax ranging from 345 to 456°C. The high oxygen index indicates that organic matter in the Paleocene units possibly generated other organic matter or alteration organic matter. Therefore we believe that Paleocene units may have gas and/or oil potential in the Tuz Gölü basin, provided that no alteration took place in organic matter.