f Factors Controlling Element Composition Variations of Organic-Rich Rocks (Taşpınar/Nallıhan)

Samples investigated in this work are composed from Paleocene-Eocene organic-rich black shales and marls of Çamalan Formation. Several geochemical (organic and inorganic) and mineralogical analysis were used for determining the factors controlling composition variations and source rock of Taşpınar organic-rich rocks. 52 samples taken from the study area suggest an average of 2,97 %wt. of organic carbon values, with a range between 0,12 and 11,32 %wt. Mineralogical analysis of 5 samples show that these rocks are mainly composed of dolomite, quartz, clay minerals, analcime, mica group with traces of feldspar and calcite. Furthermore Chemical Alteration Index (CIA) values indicate that Taşpınar samples were generated from a moderately weathered source rocks. Results of redox conditions of depositional environment obtained with several geochemical parameters such as Ni/Co, V/Cr, U/Th, and the relationship between Corg with certain elements show element compositional variations of samples. While average ΣREE values of Taşpınar samples indicate a higher ratio relatively to chondrite, these have lower ratios with average shale, PAAS, UCC.