Facies analysis, sedimentary environment and sequence stratigraphy of the lower cretaceous deposits in the Kalahroud area, at north of Esfahan, Iran

Abstract

Background/Objectives: Rocks of the Mesozoic era in Iran, especially Cretaceous period, have been studied frequently from stratigraphic point of view, but little research has been done from sedimentology viewpoint. This study aims to restore the sedimentation condition and the conditions governing the sedimentary basins during that period (lower Cretaceous). Methods: One stratigraphic section was measured along the outcrop in Kalahroud Area, at North of Esfahan. 52 thin sections samples were studied to determine the facies and a polarizan microscope was used for the procedure. Findings: Based on lithological properties, 3 lithostratigraphic units have identified in the area. Facies analysis and field observations led to identification of 6 carbonate facies, 4 terrigenous facies and also 3 mixed (terrigenous and carbonate). Kalahroud area was deposited on a homoclinal ramp setting within four zones including Continental, tidal flat, lagoon and bar environments. Sequence stratigraphic analysis identified one third-order depositional sequences in the studied area. Lower boundary in this sequence is unconformity first-type boundary (SB1) (with Jurassic deposits) and consists of Lowstand Systems Tract (LST), Transgressive Systems Tract (TST) and Highstand Systems Tract (HST). Application: These results could be used for comparison with other worldwide localities and provide additional data for lower Cretaceous paleogeographic reconstructions.