Abstract: In 1841, Murchison coined the term Permian for strata in the Russian Urals. Recognition of the Permian outside of Russia and central Europe soon followed, but it took about a century for the Permian to be accepted globally as a distinct geological system. The work of the Subcommission on Permian Stratigraphy began in the 1970s and resulted in current recognition of nine Permian stages in three series: the Cisuralian (lower Permian) – Asselian, Sakmarian, Artinskian and Kungurian; the Guadalupian (middle Permian) – Roadian, Wordian and Capitanian; and the Lopingian (upper Permian) – Wuchiapingian and Changhsingian. The 1990s saw the rise of Permian conodont biostratigraphy, so that all Permian Global Stratigraphic Sections and Points (GSSPs) use conodont evolutionary events as the primary signal for correlation. Issues in the development of a Permian chronostratigraphic scale include those of stability and priority of nomenclature and concepts, disagreements over changing taxonomy, ammonoid v. fusulinid v. conodont biostratigraphy, differences in the perceived significance of biotic events for chronostratigraphic classification, and correlation problems between provinces. Further development of the Permian chronostratigraphic scale should focus on GSSP selection for the remaining, undefined stage bases, definition and characterization of substages, and further integration of the Permian chronostratigraphic scale with radioisotopic, magnetostratigraphic and chemostratigraphic tools for calibration and correlation.

Abstract: Permian rugose corals underwent evolutionary episodes of assemblage changeover, biogeographical separation and extinction, which are closely related to geological events during this time. Two coral realms were recognized, the Tethyan Realm and the Cordilleran–Arctic–Uralian Realm. These are characterized by the families Kepingophyllidae and Waagenophyllidae during the Cisuralian, Waagenophyllidae in the Guadalupian and the subfamily Waagenophyllinae in the Lopingian, and the families Durhaminidae and Kleopatrinidae during the Cisuralian and major disappearance of colonial and dissepimented solitary rugose corals from the Guadalupian to the Lopingian, respectively. The development of these coral realms is controlled by the geographical barrier resulting from the Pangaea formation. According to the changes in the composition and diversity of the Permian rugose corals, a changeover event might have occurred at the end-Sakmarian and is characterized by the mixed Pennsylvanian and Permian faunas to typical Permian faunas, probably related to a global regression. In addition, three extinction events are present at the end-Kungurian, the end-Guadalupian and the end-Permian, which are respectively triggered by the northward movement of Pangaea, the Emeishan volcanic eruptions and subsequent global regression, and the global climate warming induced by the Siberian Traps eruption.

Abstract: Establishing a Permian brachiopod biochronological scheme for global correlation is difficult because of strong provincialism during the Permian. In this paper, a brief overview of brachiopod successions in five major palaeobiogeographical realms/zones is provided. For Gondwanaland and peri-Gondwanan regions including Cimmerian blocks, Bandoproductus and Punctocyrtella (or Cyrtella ) are characteristic of the lower Cisuralian, as is Cimmeriella for the middle Cisuralian. As the Cimmerian blocks continued drifting north during the late Kungurian, accompanied by climate amelioration, contemporaneous brachiopods inhabiting these blocks showed a distinct shift from cold-water to mixed or warm-water affinities. However, coeval brachiopods in the Northern Transitional Zone (NTZ) are characterized by warm-water faunas and are associated with fusulinids in the lower Cisuralian. The Guadalupian brachiopods of the NTZ were clearly mixed between the Boreal and palaeoequatorial affinities. The end-Guadalupian is marked by the disappearance of a few characteristic genera, such as Vediproductus , Neoplicatifera and Urushtenoidea , in the Palaeotethyan region. The onset of the end-Permian mass extinction in the latest Changhsingian is clearly exhibited by the occurrence of the dwarfed and thin-shelled brachiopods commonly containing Paracrurithyris .

The major tectonic units of the Neoarchean Volgo-Uralia continent, which is ~600,000 km 2 in area, are contrastingly expressed in regional gravity and magnetic maps. Interpretations of seismic images of the crust along the TATSEIS geotraverse in combination with 3D density and magnetic crust models provide insights into the volumetric representation of tectonic structures of various ranks. Granulite-gneiss crust of Volgo-Uralia is characterized by elevated thickness (~60 km and locally up to 65–70 km). The deep structure of Volgo-Uralia assumes that the entire crustal section, including the lower crust, is composed of high-density granulite metamorphic facies rocks. Specific structural units called ovoids play the main role in the structure of this continent. The ovoids are bowl-shaped crustal blocks, round or oval in plan view, 300–600 km across, and with the base reaching a level of crust-mantle interface at ~60 km. Ovoids are bounded by conic surfaces of reverse (thrust)-faults, along which their outer parts are thrust over the framework. The Tokmov, Buzuluk, Verkhnekamsk, Krasnoufimsk, and Orenburg ovoids, which generally are not in contact with one another, are dominated by mafic granulites, gabbroic rocks, gabbroanorthosites, and ultramafic rocks. A significant contribution of deep-seated intrusive rocks suggests that metamorphism developed in the lower and middle crust at high PT parameters that exceed the maximum estimates (940–950 °C, 9.5 kbar) recorded in samples of borehole cores. The interovoidal space is occupied by elongated oval synforms up to 200–400 km long. This space is considered to be an interovoidal domain, which includes three relatively narrow, compressed synforms (Yelabuga-Bondyug, Kilmez, Chusovaya) and four oval synforms (Srednevyatka, Verkhnevyatka, North-Tatar, Almetevsk). The Tokmov ovoid is framed in the southeast by the Tuma and Penza belts. Synforms are filled with metasedimentary granulites and mafic metaigneous rocks. The protoliths were formed over the time interval from 3.4–3.2 to 3.1–3.0 Ga. The internal zoning of the Volgo-Uralia crust is related to numerous local centers within ovoids and interovoidal region. At least two high-temperature metamorphic events were followed by periods of retrogression: 2.74–2.70 and 2.62–2.59 Ga. The areal and especially high-temperature character of tectonothermal processes during formation of the Neoarchean crust of the Volgo-Uralia Craton, and distinct geometrization of space with recognition of several concentric domains, finds a universal explanation in ascent of multiple plumes.