Environmental Criteria of Stromatolitic Limestones in The Barsrain Formation from Surface Sections, Northeastren Iraq

Abstract

The rock successions of Barsarin Formation Late Kimmeridgian was studied at three surface sections the type section "17m", Sarglu "19m" and Rania "10m"; northeastern Iraq. The detailed sedimentological study reveals that the formation consists mainly of dolomite and dolomitic limestones. A wide spectrum of diagenetic – processes are recognized in the rock successions; these are dolomitization, compaction, cementation, micritization, dissolution, replacement, neomorphism and silisification. By the far, dolomitization and compaction are the most common and widespread processes. Stromatolites are the dominant primary sedimentary structures in this Formation. Based on field observation and textural characteristics four stromatolite types are distinguished: planar, wavy, domal, and bedded. They are normally formed by carbonates (lime muds) and extensively suffered early dolomitization