Cigdem Saydam Eker
Department of Geology, Engineering Faculty, Gumushane University, 29000—Gumushane, Turkey
e-mail: csaydam@gumushane.edu.tr, csaydam@hotmail.com
Received April 09, 2010; in final form April 27, 2011
Abstract—Subaerial weathering level, source area and tectonic environments were interpreted by using petro-
graphic and geochemical characteristics of Eocene age sandstones found in the eastern Pontides. The thickness
of Eocene age clastic rocks in the eastern Pontides ranges from 195 to 400 m. Mineralogical components of
sandstones were mainly quartz, feldspar, rock fragments, and opaque and accessory minerals. Depending on
their matrix and mineralogical content, Eocene age sandstones are identified as arkosic arenite–lithic arenite
and feldspathic wacke–lithic wacke. CIA (Chemical Index of Alteration) values observed in the Eocene age
sandstones (43–55) suggest that the source terrain of the sandstones was not affected by intense chemical
weathering. Low CIW/CIA (Chemical Index of Weathering/Chemical Index of Alteration) values of the sand-
stones studied here suggest only slightly decomposed material and having undergone little transport until final
deposition. Zr/Hf, Th/Sc, La/Sc and CIA ratios are low and demonstrate a mafic source; on the other hand, high
LREE/HREE ratios and a slightly negative Eu anomaly indicate a subordinate fclsic source. Modal mineralog-
ical and SiO2/Al2O3 and K2O/Na2O and Th, Zr, Co, Sc of Eocene age sandstone contents indicate that they are
probably magmatic arc originated and deposited in the back arc basin.
Keywords: Eastern Pontides, sandstone provenance, source area, tectonosedimentary environment
DOI: 10.1134/S001670291206002X
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