Abstract The late Early Permian ( c. 278–270 Ma) supra-subduction zone (SSZ) Dun Mountain ophiolite is bordered to the east by the Pataki Melange and to the NE by the Croisilles Melange. In the south, the ophiolite passes into a dismembered incipient oceanic arc (Otama Complex). The above units represent an oceanic forearc generated above a west-dipping subduction zone. Terrigenous sediment reached the subduction trench after the Mid-Permian(?) docking of the oceanic forearc with the long-lived SE Gondwana active continental margin. Mixed terrigenous–volcaniclastic turbidites accumulated in the trench prior to and during melange accretion. Fragments of the overriding oceanic forearc (and incipient arc, locally) detached and mixed to form melange and broken formation. Despite some individual features (e.g. of the basalt chemistry), the Patuki and Croisilles melanges are interpreted as originally representing a single Permian trench–accretionary complex. The more distal (easterly) part was sliced into the adjacent accretionary complex of the Caples Terrane to form the Croisilles Melange (and equivalent Greenstone Melange) probably after the Triassic. The South Island melanges exemplify accretionary processes in which igneous and sedimentary rocks were detached from the overriding plate by subduction–erosion, together with accretion, including seamount material from the subducting oceanic plate, with implications for melanges elsewhere.

Abstract The Dun Mountain ophiolite and related oceanic-arc rocks (Otama Complex) formed above a westward-dipping subduction zone within Panthalassa, with implications for the emplacement of Cordilleran-type ophiolites and arcs elsewhere. The ophiolite is overlain by the Mid–Late Permian Upukerora Formation (up to 850 m), a predominantly very coarse breccia-conglomerate that mainly accumulated by mass flow. Lesser amounts of sediment accumulated from turbidity currents and as background hemipelagic sediments. The succession unconformably overlies ophiolitic basaltic or, rarely, gabbroic rocks after a regional hiatus. Much of the coarse clastic debris was derived from the underlying ophiolite. However, clasts of plagioclase-phyric basalt, felsic volcanics and quartz-bearing intrusive rocks, including plagiogranite, are over-represented compared to the ophiolite. The evolved igneous material was derived from an incipient oceanic arc (the Otama Complex) that bordered or covered the ophiolite, especially in the south. The coarse clastic material accumulated following the activation of north–south-trending, subaqueous, extensional growth faults within the underlying oceanic crust. Large blocks of mainly basalt, diabase and gabbro were also shed down fault scarps from relatively shallow-water to deeper-water settings. Fault-controlled talus accumulated soon after Mid-Permian docking of the ophiolite and oceanic arc with SE Gondwana to initiate the Mid-Permian–Mid-Triassic Maitai continental margin forearc basin.

Abstract The Mid-Late Permian–Mid-Triassic Maitai Group is interpreted as the distal forearc basin of the SE Gondwana active continental margin. The basin initially received very coarse detritus (Upukerora Formation) from the recently emplaced, nearby Dun Mountain ophiolite and related oceanic-arc rocks. Early tectonic subsidence accommodated up to 1000 m of bioclastic gravity-flow deposits from an adjacent carbonate platform, together with terrigenous and volcanic arc-derived material (Wooded Peak Formation). Basin-levelling turbidites then accumulated, composed of mixed terrigenous and arc-derived igneous material, with bottom-current reworking (Tramway Formation). Latest Permian–earliest Triassic gravity-flow deposits (locally absent) are characterized by relatively basic volcanic material (Little Ben Formation). Overlying turbidites accumulated in a relatively oxygen-poor, deeper-water setting (Greville Formation). Fine-grained background sedimentation then switched to well-oxidized, with traction-current reworking (Waiua Formation). The overlying Early–Mid Triassic Stephens Subgroup included the accumulation of lenticular sandstone turbidites, channelized conglomerate, well-oxidized deep-sea mud and felsic tuff. Permian and Early Triassic marginal carbonate platforms collapsed and were emplaced as localized exotic blocks. Extrusive and intrusive clasts within channelized conglomerates (Snowdon Formation) were derived from the adjacent continental margin arc. The forearc basin was subsequently displaced to its present position, possibly with up to 3000 km of southwards translation.

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: Radioisotopic age determinations targeted at key stratigraphic successions worldwide continue to refine the geological timescale with increasing precision and accuracy and to unravel the tempo of global geological, palaeoclimatic and palaeobiotic processes that have shaped our planet. The last decade has witnessed significant progress in the calibration of the Permian Period through integrated stratigraphic, palaeontological and high-precision geochronological investigations. These studies have largely focused on the Cisuralian and Lopingian stages, particularly the end-Permian mass extinction, whereas much of the Guadalupian and its associated events remain inadequately calibrated. A compilation of the high-precision U–Pb geochronology generated in the past ten years yields ages of 298.92±0.19 Ma for the onset of the Permian, 293.52±0.17 Ma for the base-Sakmarian, 290.10±0.14 Ma for the base-Artinskian, 272.95±0.11 Ma for the Cisuralian–Guadalupian boundary, 265.22±0.34 Ma for the base-Capitanian, 254.14±0.12 Ma for the base-Changhsingian and 251.90±0.10 Ma for the Permian–Triassic boundary. Extension of modern astrochronological methods to the Palaeozoic Era presents new opportunities for broader stratigraphic correlations and enhanced calibration of the Permian timescale. Supplementary material: Table S1 (U–Pb data) is available at https://doi.org/10.6084/m9.figshare.c.3917425

Abstract: The secular evolution of the Permian seawater 87 Sr/ 86 Sr ratios carries information about global tectonic processes, palaeoclimate and palaeoenvironments, such as occurred during the Early Permian deglaciation, the formation of Pangaea and the Permian–Triassic (P–Tr) mass extinction. Besides this application for discovering geological aspects of Earth history, the marine 87 Sr/ 86 Sr curve can also be used for robust correlations when other bio-, litho- and/or chemostratigraphic markers are inadequate. The accuracy of marine 87 Sr/ 86 Sr reconstructions, however, depends on high-quality age control of the reference data, and on sample preservation, both of which generally deteriorate with the age of the studied interval. The first-order Permian seawater 87 Sr/ 86 Sr trend shows a monotonous decline from approximately 0.7080 in the earliest Permian (Asselian) to approximately 0.7069 in the latest Guadalupian (Capitanian), followed by a steepening increase from the latest Guadalupian towards the P–Tr boundary ( c. 0.7071–0.7072) and into the Early Triassic. Various higher-order changes in slope of the Permian 87 Sr/ 86 Sr curve are indicated, but cannot currently be verified owing to a lack of sample coverage and significant disagreement of published 87 Sr/ 86 Sr records. Supplementary material: Numbers, information, data and references of the samples discussed are available at https://doi.org/10.6084/m9.figshare.c.3589460

Abstract: Forty Permian conodont biozones are summarized and 35 additional regional zones are correlated. The Lower Permian is largely zoned on the basis of partial range lineage interval zones of species of Streptognathodus , Sweetognathus , Neostreptognathodus and Mesogondolella . The Middle and Upper Permian are zoned, respectively, on the basis of partial range lineage interval zones of species of Jinogondolella and Clarkina . The ranges of all key taxa to develop this zonation are depicted in relation to the geochronological ages of Permian stages. The lowest Permian succession has been astronomically tuned with 400 kyr cyclothems linked to interpolated ages in the Uralian succession.

Abstract: Tetrapod footprints are among the most common fossil remains in continental Permian strata and thus are of biostratigraphic interest. Based on the vertical distribution of the 13 best-known Permian tetrapod ichnotaxa, three footprint biochrons are suggested for the period: (1) Dromopus – latest Carboniferous (approximately Gzhelian) to late Early Permian (approximately Artinskian), representing ichnoassemblages dominated by tracks of temnospondyls, reptiliomorphs, pelycosaurs and early diapsids; (2) Erpetopus – late Early Permian (approximately Kungurian) to late Middle Permian (approximately Capitanian), representing ichnoassemblages dominated by tracks of non-diapsid eureptiles; and (3) Paradoxichnium – Late Permian (Wuchiapingian and Changhsingian), representing ichnoassemblages dominated by tracks of medium- and large-sized parareptiles, non-diapsid eureptiles and early saurians. This is the most conservative ichnostratigraphic concept, and it may be possible to refine it to almost stage-level resolution by future comprehensive analysis, especially of Permian captorhinomorph and therapsid footprints. Other major tasks to improve Permian tetrapod footprint ichnostratigraphy include enhanced knowledge of Middle Permian tetrapod footprints, and clarification of the palaeoenvironmental factors that may control the distribution of tetrapod footprints in space and time.