Facies Analysis, Depositional Environment and Cyclostratigraphy of the Lower Permian Deposits Chili formation in the Kalmard Block, East Central Iran (godar-e-gachal Section)

Abstract

Lower Permian deposits in Kalmard region recognize with informal Group of Khan. They have various features in the different places. This Formation consists of carbonate and sandstone rocks. Chili Formation encompassing 170 meters of carbonate deposits with thick to massive sandstone and sandy limestone interbeds. Lower boundary of this Formation is disconformable with member D of Gachal Formation; and upper boundary, is disconformable with unnamed Lower Permian deposits. According to the lithological characters and microscopic studies, the above mentioned section divided into 20 carbonate microfacies. The combination of field and microscopic studies, cause identifications of beach, Intratidal, open and semi-restricted lagoon, shoals and bar, tidal channel and open marine sub-environments for the Chili Formation. Vertical changes of microfacies and depth changes curve show much more thickness of shoals and bar, lagoon and beach microfacies, and little thickness of open marine, tidal channel microfacies. Chili Formation in Godar-e-Gachal section precipitation in the gentle gradient Homoclinal ramp in the south of Paleotethys Ocean. In sequence stratigraphy view carbonate-sandstone succession in Chili Formation are formed from four Depositional Sequences (DS) which are separated by type 2 Sequence Boundaries (SB2). Depositional sequence 1 of this Formation separated from member D of Gachal Formation and Depositional sequence 4 of Chili Formation separated from unnamed Lower Permian deposits by type 1 Sequence Boundary (SB1). Four depositional sequences in this Formation show Sakmarian age which has adaptation with lower Absaroka II, III. The upper erosioned boundary, between of Chili Formation and member D of Gachal Formation have conformable with falling of sea level in global scale.