Biostratigraphy and Sequence Stratigraphy of the Tarbur Formation (Maastrichtian) from Iranian Zagros Foreland Basin, Southwest of Iran

Shallow carbonate deposits(Tarbur Formation)were formed in the Zagros foreland basin with dynamic tectonics during the Maastrichtian age.From the viewpoint of reconstruction of depositional conditions in these deposits,studies of biostratigraphy,microfacies,microtaphofacies,and sequence stratigraphy were performed in a single area at Tang-e Shabi Khoon,northwest of Zagros.Based on the identification of two assemblage zones consisting of benthic foraminifera in these strata,the formation was deposited during the middle to late Maastrichtian.The number of cycles in test size and type of coiling in Loftusia decreased from the study area toward the northwest of the Neotethys basin.The input of clastic sediments affected the distribution of Loftusia and rudists in the study area.Nine microfacies,six microtaphofacies,and one terrigenous facies(shale)were identified based on the sedimentary features.These deposits of the middle-late Maastrichtian were deposited on a homoclinal carbonate ramp.The platform can be divided into restricted and semi-restricted lagoon,shoal,and open marine environments.In the study area,the deposits of the Tarbur Formation were deposited during four third-order depositional sequences.Local fault activities affected the formation of depositional sequences in the study area.     

Saqez–Sardasht Goldfield, North Sanandaj-Sirjan Zone, Iran: A Tectono-Metallogenic Synthesis

The Sanandaj–Sirjan Zone (SSZ), as the metamorphic-magmatic core of the Zagros Orogen in southwestern Iran, contains several styles of gold deposit of Phanerozoic age. The northern SSZ includes an ENE-trending goldfield belt. This area that encompasses the main orogenic gold deposits, e.g., Qolqoleh, Kervian, Qabaqhlujeh, and the Barika VMS goldfield, was chosen for this research to study the spatial and temporal relationships between gold mineralization and orogenic phases. Regarding the rock unit variations, metamorphism, magmatism and the settings of the structures, the study area is divided into four distinct tectonic blocks, separated by three main NW-trending thrust faults (suture lines) including, from NE to SW, the Tamugheh, the Ebrahim Hesar and the Zagros main thrust (ZMT) faults. The area between the Tamugheh and Ebrahim Hesar faults is a tectonized/uplifted basement of accretionary wedge-originated thrust slivers, hosting the above orogenic gold mineralizations. The other area between the here termed Ebrahim Hesar fault and the ZMT is an island-arc basin, proposed here as the Sardasht–Barika zone, including the only recognized massive sulfide gold district all over the SSZ, named Barika. The Barika goldfield was metamorphosed, deformed and enriched due to the island-arc collision to the Arabian continent, before the closure of Neotethys on the eastern flank.