Permian fusulinid assemblages and stratigraphy of the transcaucasia

The Permian sequence of the Transcaucasia, which comprises the Davaly, Asni , Gnishik, Arpa, Khachik, and Akhura Formations, is described. A precise da ting of the formations based on the analysis of fusulinid assemblages is al so provided. The Davaly Formation corresponds to the Bolorian Stage of the Lower Permian (Cisuralian); the Asni Formation corresponds to the Kubergand ian Stage, and to the lower half of the Murgabian Stage of the Middle Permi an (Guadalupian); the Gnishik Formation corresponds approximately to the up per half of the Murgabian Stage; and the Arpa and Khachik Formations repres ent the entire Midian Stage of the Middle Permian. Only che uppermost Chana khchy Beds of the Khachik Formation are referred to the upper series of the Permian (Lopingian), based on the latest proposal of the International Sub commission on Permian Stratigraphy concerning series boundaries. The Akhura Formation encompasses the Dzhulfian and Dorashamian Stages of che Upper Pe rmian. Refined correlations between the Permian sequence of the Transcaucasia and the most complete Permian sequences of the Tethyan region (Central Iran, so uthestern Pamirs, South China, Japan) are presented. The transgressive over lapping of the Permian deposits is recorded in these areas, similar to the Transcaucasia. Although the transgression began during the Bolorian, it rea ched the widest extent in the Kubergandian and therefore, in most sections the transgressive series begins with deposits of Kubergandian age. The Midd le and Upper Permian deposits of the Transcaucasia, Iran, and southern Turk ey belonged to a single carbonate platform. Similar extensive carbonate pla tforms are recorded in the southern parts of Afghanistan and China. A chang e in the sedimentary regime was recorded in all these platforms at the boun dary between the Guadalupian and Lopingian epochs. The Guadalupian time was marked by the intensive accumulation of biolitithic and detrital limestone s produced by benthic organisms, mainly algae and foraminifers, whereas in the Lopingian time, carbonate and clayey micritic deposition dominated, and the role of nectonic-planctonic and nectonic organisms, such as cephalopod s and conodonts, increased. The sedimentation change was abrupt and caused probably by the short-term post-Midian regression. The change resulted in a significant biotic crisis when larger fusulinids, goniatitids and agoniati tids, tabulate corals, most rugose corals and other organisms became extinc t. These events marked the onset of the Late Permian "Great Extinction", wh ich ended at the Permian/Triassic boundary. Nine paleontological places sho w the main fusulinid assemblages. Nine new species are described: Codonofus iella (?) vediensis, Chalaroschwagerina davalensis, Pseudofusulina arpaensi s, P. araxensis, P. pjatakovae, Rugosochusenella davalensis, Misellina (Mis ellina) caucasica, Cancellina armenica, and Sumatrina vediensis.