Sedimentological investigation of the upper jurassiclower cretaceous berdiga limestone in the Alucra-Gümüşhane-Bayburt regions (Eastern pontids, ne Turkey)

SEDIMENTOLOGICAL INVESTIGATION OF THE UPPER JURASSIC-LOWER CRETACEOUS BERDÎGA LIMESTONE IN THE ALUCRA-GÜMÜŞHANE-BAYBURT REGIONS (EASTERN PONTIDS, NE TURKEY) ABSTRACT This study has been carried out for the sedimentologi- cal investigation of the Upper Jurassic-Lower Cretaceous Berdiga Limestone sequence, which is extensively exposed in the Southern Zone of the East Pontid. With this aim, stra- tigraphical sections have been measured and samples have been collected sistematically from the sections of the unit exposed in the Suiçti (Alucra), Gelinpertek (Köse), Keçi De resi (Gümüşhane), Danzot (Bayburt) and Karacık Tepe (Bay burt) regions. Microscopic investigations of samples and lithofacies studies have been revealed that the Berdiga Limestone sequ ence have been developed in different lithofacies. According to the stratigraphical positions in the measured sections these lithofacies that have been deposited in different time intervals and environments and that are showing different textural and also partially different lithological features as follows; -Neomorfic limestone lithofacies, -Conglomerate-sandstone-sandy limestone lithofacies, -Rudstone lithofacies, -Peloidal packstone-wackestone lithofacies, -Oolitic grainstone and/or ooidal grainstone-packstone lithofacies, -Turbiditic limestones lithofacies, -Mudstone lithofacies, -Rudstone-grainstone-packstone 1 ithof acies, -Sandstone-sandy limestone-limestone lithofacies, -Dolostone lithofacies, -Peloidal grainstone-mudstone lithofacies, -Skelatal packstone-wackestone lithofacies, -Intraclast grainstone-wackestone lithofacies and dolo- stone-dolomitic grainstone-packstone lithofacies, -Ooidal grainstone and skelatal packstone-wackestone lithofacies, -Floatstone lithofacies. In addition, the vast number of these described lithofacies are locally developed and the minority of which are regio nally developed. Berdiga Limestone are deposited in and be gin their diagenetic history in the marine phreatic environ ment, and then continiued in the diagenetic realms of mixing zone, fresh water phreatic environment, wadose zone and deep burial environment. A number of diagenetic product indica ting these diagenetic realms are seen extensively in diffe rent lithofacies t( sometimes in single lithofacies). On the other hand, secondary silicif ication seen almost in all lit hofacies and particularly on some skelatal grains (echino- derm, Requienia and Toucasia) is developed in the different diagenetic realms from early diagenetic to late diagenetic. VII