ÇAĞRILI KONUŞMALAR / KEYNOTES Invited Speeches ... - TPJD

Investigation of Redox, Provenance and Tectonic Setting of Organic Carbon-
Rich Rocks from the Himmetoğlu (Bolu/Turkey) Field
Demet Banu Koralay 1 , Yasemin Geze Kalanyuva 2 , Ali Sarı 3
1 Pamukkale University, Denizli
2 Turkish Petroleum Corporation, Exploration Department, Ankara
3 Ankara University, Faculty of Engineering, Department of Geological Engineering, Ankara
Among the terrigenous sedimentary rocks, shales are considered to represent the average
crustal composition of the provenance much better than any other siliclastic rocks. Shales retain
most of the mineral constituents of the source and their bulk chemistry preserves the nearorginal
signature of the provenance and more faithfully reveal palaeoweathering conditions. The
present study examines the geochemistry of organic carbon-rich shales and coals. Study area
is the Himmetoglu coal and bituminous shale basin in Goynuk (Bolu) district. The stratigraphic
section from bituminous shales and coals were collected 38 samples. Organic geochemical (Rock-
Eval/Corg), inorganic geochemical (X-ray fluorescence, XRF), and mineralogical studies (scanning
electron microscope, SEM and X-ray difraction, XRD) of samples were performed, and to these
investigations have been made an approach the redox conditions of depositional environments,
their source rocks, paleoweathering and tectonic setting of the provenance. Degree of pyritization
(DOP) values, V/V+Ni (0.11-0.91) and U/Th ratios (0.44-17.85) of the bituminous shales and
coals suggests that anaerobic, or euxinic, dysoxic-anoxic and suboxic-anoxic redox conditions
respectively. Mean major elemental composition of the bituminous shales and coals is in fair
concurrence with that of the Average shale, North American Shale Composite, Upper crust, and
Post-Archean Average Shale. Chemical index of alteration investigations imply weak weathering
of the source material that constitute both bituminous shales and coals. Plots of bituminous
shales and coals on tectonic setting discrimination diagram reveal an active continental margin
setting for the provenance.
Keywords: Himmetoğlu Basin, bituminous shale, coal, redox conditions, provenance
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