Hydrothermal Fluids and Cold Meteoric Waters along Tectonic-Controlled Open Spaces in Upper Cretaceous Carbonate Rocks, NE-Iraq: Scanning Data from In Situ U-Pb Geochronology and Microthermometry

The Upper Cretaceous carbonates along the Zagros thrust-fold belt “Harir-Safin anticlines” experienced extensive hot brine fluids that produced several phases of hydrothermal cements, including saddle dolomites. Detailed fluid inclusion microthermometry data show dolomites precipitated from (83–160 °C) and saline (up to 25 eq. wt.% NaCl; i.e., seven times higher than seawater salinity). interacted with brine/rocks during their circulation before invading carbonates. Two entrapment episodes (early late) FIs “HT” cements are recognized. early episode is linked fault-related fractures was contemporaneous precipitation HT cements. inclusions leaked were refilled a later diagenetic phase. late consistent low (0.18 2.57 NaCl) which had meteoric origin. Utilizing laser ablation U-Pb age dating method, two numerical absolute ages ~70 Ma 3.8 identified calcrete levels in These obtained same level indicate this unit twice exposed subaerial conditions. earlier exposure associated alveolar other features, such as dissolution, micritization, cementation, while second laminae, pisolitic, microstromatolite features formed regional uplifting area Pliocene times. In conclusion, hydrothermal-saddle high temperature fluids, entrapped large monophase very salinity inclusions, indicative for water