ÇAĞRILI KONUŞMALAR / KEYNOTES Invited Speeches ... - TPJD

Factors Controlling Element Composition Variations of Organic-Rich Rocks
(Taşpınar/Nallıhan)
Derya Koca 1 , Ali Sarı 2
1 Ankara University, Graduate School Of Natural And Applied Sciences, Ankara
2 Ankara University, Faculty of Engineering, Department of Geological Engineering, Ankara
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 ∑REE
values of Taşpınar samples indicate a higher ratio relatively to chondrite, these have lower ratios
with average shale, PAAS, UCC.
Keywords: Geochemistry, provenance, black shales, organic matter, rare earth element
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