Paragenetic sequence interpretation of Upper Cretaceous carbonates of northeast of Bajestan


Upper Cretaceous cliff forming limestones exposed at north of Bajestan (NW Khorassan Razavi pronince). These rocks are composed of skeletal calcarenite to calcirudite with calcareous shale interbeds. Two stratigraphic sections were measured and 160 samples collected for petrographical and geochemical analysis. 11 lithofacies and three facies associations have been identified that may have been deposited in a carbonate platform ramp type. The most important diagenetic features identified, include cementation, micritization, boring, neomorphism, chemical and physical compaction, fracturing and vein filling, replacement, pyritization and dissolution. Carbon and oxygen isotopes values vary from 0.85 to 3.49 and -8.55 to -2.23 per mil PDB, respectively. These variation as well as elemental cross plots reviewed burial diagenetic realm that is supported by petrographic evidences. Carbonate rocks of Bajestan deposited in warm