Late Middle Permian Research Articles

Transgressive–regressive sequences on the slope of an isolated carbonate platform (Middle–Late Permian, Laibin, South China)

From the Middle to Late Permian, the Laibin area in Guangxi, South China, was situated on the slope of an isolated carbonate platform, on which continuous marine successions were deposited. Two global stratotype sections for the boundary between the Guadalupian (Middle Permian) and Lopingian (Late Permian) are located at Penglaitan and Tieqiao in the Laibin area, respectively, and thus are chosen for study. At the two locations, 14 facies are recognized in the Maokou and Heshan Formations, and they are further grouped into four facies associations (basin, lower slope, upper slope, and platform margin). Six main transgressive–regressive (TR) sequences are identified in strata from the Roadian (Middle Permian) to the Wuchiapingian (Late Permian). They are conformable marine sequences that were little influenced by regional uplift (Dongwu Movement) and so provide a good record of the sea-level changes in South China at this time. Based on the significant taxonomic selection and controversial marine faunal loss in the end-Guadalupian mass extinction, and the Middle-Late Permian sea-level changes recorded by the TR sequences in the Laibin area, it is suggested that this extinction event might have been triggered by the reduction and loss of shallow-marine habitat area caused by the end-Guadalupian regression. The global cooling and Emeishan volcanism also occurring at this time could have further enhanced this extinction event.

The Capitanian (Permian) minimum of 87Sr/86Sr ratio in the mid-Panthalassan paleo-atoll carbonates and its demise by the deglaciation and continental doming

The Capitanian minimum in the Permian represents one of the most significant features in the Phanerozoic seawater 87Sr/86Sr history. In order to establish the detailed Sr chemostratigraphy around the Guadalupian minimum, 87Sr/86Sr ratios were measured for the Capitanian (upper Middle Permian) paleo-atoll limestones at Akasaka in Japan. The limestone was primarily deposited on a paleo-seamount in the low-latitude mid-Panthalassa, and was secondarily accreted to Japan (South China block) margin in the Jurassic. As being free from local continental influences, the Akasaka limestone recorded well-mixed seawater isotope composition of the Permian low-latitude mid-superocean. We detected extremely low 87Sr/86Sr ratios (ca. 0.7068–0.7069) in the 70m-thick Capitanian interval, immediately below the Guadalupian–Lopingian (Middle-Late Permian) boundary (G–LB), of the Akasaka limestone. This Sr isotopic profile at Akasaka suggests that the global seawater was least affected by radiogenic continental flux throughout the Capitanian. As these values correspond to the lowest in the Paleozoic, this interval with low 87Sr/86Sr ratios, lasted for at least some milllion years, represents the Capitanian minimum, which marks the significant turning point from the Late Paleozoic decrease to Early Mesozoic increase in seawater 87Sr/86Sr ratio. The geological lines of evidence indicate that the Capitanian minimum was caused likely by the mid-Permian cooling that may have driven extensive ice-cover over continental crusts to suppress continental flux enriched in radiogenic Sr into the superocean. The rapid increase in 87Sr/86Sr values after the minimum can be explained either by the deglaciation or by the Pangean rifting.

Diversity trends in the establishment of terrestrial vertebrate ecosystems: Interactions between spatial and temporal sampling biases

Research Article| January 01, 2013 Diversity trends in the establishment of terrestrial vertebrate ecosystems: Interactions between spatial and temporal sampling biases Roger B.J. Benson; Roger B.J. Benson * 1Department of Earth Sciences, University College London, Gower Street, London WC1E 6BT, UK2Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK *E-mail: rbb27@cam.ac.uk. Search for other works by this author on: GSW Google Scholar Paul Upchurch Paul Upchurch 1Department of Earth Sciences, University College London, Gower Street, London WC1E 6BT, UK Search for other works by this author on: GSW Google Scholar Geology (2013) 41 (1): 43–46. https://doi.org/10.1130/G33543.1 Article history received: 19 Apr 2012 rev-recd: 04 Jul 2012 accepted: 05 Jul 2012 first online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Roger B.J. Benson, Paul Upchurch; Diversity trends in the establishment of terrestrial vertebrate ecosystems: Interactions between spatial and temporal sampling biases. Geology 2013;; 41 (1): 43–46. doi: https://doi.org/10.1130/G33543.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Analyses of how fossil record sampling influences detection of past biodiversity change, and geographic patterns of animal diversity, are central to understanding macroevolution, deep time macroecology, and interactions between the rock and fossil records. The diversification and establishment of complex trophic structure among terrestrial vertebrates (tetrapods) and three hypothesized mass extinctions occurred in the Permian (299.0–252.3 Ma), during a predominantly icehouse global climate regime. Prominent, short-lived features of Permian species diversity curves, such as a possible end-Guadalupian mass extinction, are robust to sampling biases. However, multivariate and time series approaches show that longer term trends in the accumulation of terrestrial biodiversity are more sensitive. Olson’s extinction, believed to have occurred at the end of the Early Permian, might be an artifact of the abrupt geographic shift from predominant sampling of Lower Permian, amphibian-rich, paleotropical everwet biome in North America, to more tetrapod-depauperate Middle–Late Permian, cool paleotemperate biomes in Russia and South America. Thus, geographic heterogeneity in fossil record sampling, superimposed on a prominent, icehouse latitudinal biodiversity gradient, might have created an artifactual macroevolutionary event. This apparent event remains even after correcting data for uneven temporal sampling. Thus, a complex interplay between spatial and temporal biodiversity trends, and geographic and temporal sampling factors, is responsible for generating observed past biodiversity patterns. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Late Paleozoic Foraminifers from Limestone Blocks and Fragments of the Permian Tsunemori Formation and Their Connection to the Akiyoshi Limestone Group, Southwest Japan

Abstract. Late Early Carboniferous (late Visean) to late Middle Permian (Capitanian) foraminifers have been recovered from limestone blocks and fragments contained in the Tsunemori Formation in Yamaguchi Prefecture, Southwest Japan, which is unconformably overlain by the Upper Triassic Mine Group. An analysis of the Tsunemori fauna shows an almost identical composition with that of the Akiyoshi Limestone Group. The ages of the limestone clasts of the Tsunemori Formation nearly completely coincide with those of the strata of the Akiyoshi Limestone Group. The Akiyoshi Limestone Group is subdivided into 28 foraminiferal zones, and faunal elements corresponding to 24 of these 28 zones are recognized in limestone blocks and fragments of the Tsunemori Formation. Species from the remaining four zones (late Visean Endothyra sp. Zone, the late Moscovian Fusulinella bocki Zone, early Asselian Sphaeroschwagerina fusiformis Zone, and Bolorian Misellina dyhrenfurthi Zone) in the Akiyoshi Limestone Group have not been ...

Combined U-Pb SHRIMP and Hf isotope study of the Late Paleozoic Yaminué Complex, Rio Negro Province, Argentina: Implications for the origin and evolution of the Patagonia composite terrane

We have carried out zircon U-Pb SHRIMP dating and Hf isotope determinations on a biotite paraschist and on a tonalitic orthogneiss of the Yaminué Complex, and re-evaluate this complex in the broader context of the tectonic evolution of the Patagonia composite terrane. In the metasedimentary unit (msuYC), the youngest detrital zircon dated at 318 ± 5 Ma (Mississippian/Pennsylvanian boundary) indicates a Pennsylvanian (or younger) depositional age. The three main age populations peak at 474, 454 and 374 Ma. Preliminary Hf isotope data for two detrital zircons (447 and 655 Ma) yielded ε(Hf) values of −0.32 and 0.48, indicating that their primary sources contained small amounts of recycled crustal components (of Calymmian age; TDM 1.56 Ga). Zircons from the orthogneiss (miuYC; intrusive into msuYC) show a crystallization age of 261.3 ± 2.7 Ma (Capitanian; late middle Permian) which is broadly coeval with deformation, and Neoarchean–Paleoproterozoic inheritance. Meaningful core-rim relationship between Neoarchean zircon cores and late Permian rims is well defined, indicating the occurrence of Archean crust in this sector of Patagonia. Hf TDM of Permian zircons is mainly Meso-Paleoarchean (2.97–3.35 Ga), with highly negative ε(Hf) values (ca. −33). Hf TDM of inherited Neoarchean zircon cores is also Meso-Paleoarchean (3.14–3.45 Ga) but more juvenile (ε(Hf) = −0.3). Hf isotopes reinforce the presence of unexposed ancient crust in this area.Combining geological and isotope data, as well as geophysical models, we identify the Yaminué Complex within the La Esperanza-Yaminué crustal block flanked by two other, distinct crustal blocks: the Eastern block which forms part of the Patagonia terrane sensu stricto, located in the eastern Patagonian region, and the Western block forming part of the Southern Patagonia terrane. Their origins and timing of amalgamation to form the Patagonia composite terrane are also discussed.

Mineralogy and geochemistry of Late Permian coals from the Taoshuping Mine, Yunnan Province, China: Evidences for the sources of minerals

This paper describes the mineralogy and geochemistry of a batch of 17 coal samples covering the Late Permian Longtan Formation from a drill core from the Taoshuping mine, eastern Yunnan Province, China. The results show that minerals in the coals include quartz, kaolinite, calcite, chamosite, pyrite, mixed-layer I/S and minor marcasite, siderite, anatase, ankerite, and dolomite. Modes of occurrences of authigenic quartz and chamosite suggest that they were mainly precipitated from Fe–Mg-rich siliceous solution derived from the weathering of Emeishan basalt, which was induced by mantle plume eruption during late Middle Permian and covers most places of southwest China. Kaolinite and mixed layer I/S are mainly of detrital origin. Correspondingly, the elevated trace elements, including V, Cr, Co, and Ni, in the coals are closely related to Emeishan basalt. Trace amounts of detrital calcite, ankerite and siderite in the coals probably originated from the Maokou limestone. The frequent presence of high temperature quartz indicates that felsic volcanic eruption took place through the entire Late Permian Epoch. Mineral matter in the coals was not only derived from Emeishan basalt in the Kangdian Oldland, but also felsic volcanic ashes, mafic volcanic ashes, and limestone of the Maokou Formation.

First records of hindwings of Permian beetles (Coleoptera)

Three isolated hindwings of beetles are described from the locality of Isady, late Middle Permian of northern European Russia. The wings share all main features characteristic of beetles and combine plesiomorphic and apomorphic states of characters found in different suborders. The wings most probably belonged to beetles of the families Asiocoleidae and/or Taldycupedidae.

Preservation of exceptional vertebrate assemblages in Middle Permian fluviolacustrine mudstones of Kotel'nich, Russia: stratigraphy, sedimentology, and taphonomy

The Kotel'nich locality in European Russia has long been a rich source of high-quality tetrapod fossils, including pareiasaurs, dicynodonts, gorgonopsians and theriodonts. The age of the Kotel'nich locality has been debated, but it corresponds to early Severodvinian in the Russian stratigraphic scheme, equivalent to the late Capitanian (late Middle Permian) on the international time scale. Remarkably, the majority of specimens are complete, quite unlike those from most Russian Permo-Triassic red bed localities; commonest of all are 1–2-metre long pareiasaur skeletons of the genus Deltavjatia, preserved in hollows on top of a consolidated palaeosol horizon. Previous taphonomic scenarios in the Russian literature have included suggestions that the animals were overwhelmed beneath sand dunes, mired in soft fluviatile sediments, caught at the bottom of a deep lake, trapped in burrows, or dumped in fluviatile scours. It is probable that the pareiasaurs were searching for water in a time of catastrophic aridification, and died, weakened, in shallow hollows. In this case, we also emphasise the importance of floodplain microtopography in creating the sedimentary conditions necessary for the preservation of exceptional vertebrate assemblages in a slowly aggrading fluviolacustrine setting.

The detailed bio- and chemostratigraphy (d13Ccarb, 87Sr/86Sr) of the mid-oceanic limestone around the G-L (Middle-Late Permian) boundary: Akasaka Limestone case

The detailed bio- and chemostratigraphy (d13Ccarb, 87Sr/86Sr) of the mid-oceanic limestone around the G-L (Middle-Late Permian) boundary: Akasaka Limestone case

Shallow burial dolomitisation of Middle–Upper Permian paleosols in an extensional tectonic context (SE Iberian Basin, Spain): Controls on temperature of precipitation and source of fluids

This work is focused on carbonate paleosols developed in three stratigraphic sections (Landete, Talayuelas and Henarejos) of the Middle–Late Permian Alcotas Formation in the SE Iberian Basin. The Alcotas Formation, of alluvial origin, was deposited in semi-connected half-grabens developed during the early stages of the Permian–Triassic rifting stage that affected the Iberian Basin. The studied sections were located in two of these half-grabens, the Henarejos section being much closer to the basin boundary fault than the other two sections. The mineralogy and texture of the carbonate precursor of paleosols in the three studied sections are not preserved because original carbonate is replaced by coarse crystals of dolomite and/or magnesite. Dolomite crystals are typically euhedral, displaying rhombohedral shapes and reddish luminescence, although in the Henarejos section dolomite displays non-planar boundaries and frequently saddle habit. Micas are deformed and adapted to dolomite crystals, which, in turn, are affected by stylolites, suggesting that dolomite precipitated before mechanical and chemical compaction. Carbon and oxygen isotopic compositions of dolomite from the three sections show different values (δ 13C VPDB mean values = − 6.7‰, − 5.5‰ and − 7.5‰; δ 18O VPDB mean values = − 4.0‰; –5.6‰ and − 8.2‰, at Landete, Talayuelas and Henarejos sections, respectively). The 87Sr/ 86Sr ratios are similar in the three sections yielding values between 0.71391 and 0.72213. The petrographic and geochemical features of dolomite in the three studied sections suggest precipitation from similar fluids and during shallow burial diagenesis. Assuming that the minimum temperature for dolomite precipitation in the Henarejos section was 60 °C (as suggested by the presence of non-planar saddle habit), and that the dolomitizing fluid had similar δ 18O values at the three localities, then dolomite in the Talayuelas and Landete sections precipitated at temperatures around 16 and 25 °C cooler, respectively. In addition, the δ 18O VSMOW values of the water from which dolomite precipitated would have ranged between − 0.3 and − 2.9‰. Dolomite is partially or totally replaced by non- to dark dull luminescent magnesite in the Landete and Talayuelas sections. Magnesite crystals are affected by stylolites, indicating that it precipitated before chemical compaction. The δ 13C mean values are − 6.5 and − 6.0‰ and the δ 18O VPDB mean values are − 6.7 and − 7.8‰, in the Landete and Talayuelas sections, respectively. The 87Sr/ 86Sr ratios of magnesite are similar in both sections yielding values between 0.71258 and 0.72508. This suggests that they probably precipitated from similar fluids during progressive burial and at higher temperatures than dolomites at the same sections. Assuming that magnesite precipitated from a fluid with similar δ 18O values in both sections, then it had to precipitate at a temperature around 8 °C higher in Talayuelas than in the Landete section. Dolomitisation and magnesite precipitation probably occurred via reflux of saline to hypersaline brines from the overlying Mid-Late Triassic Muschelkalk and/or Keuper facies. The temperatures inferred for dolomite precipitation, however, are too high for shallow burial if a normal geothermal gradient is applied. Thus, it can be inferred that saline fluids were heated as they flowed through the syn-sedimentary extensional faults that controlled Middle Permian to Middle Triassic sedimentation; consequently fluids would have been at higher temperatures near the Henarejos area, which was closer to the basin boundary fault than at the Talayuelas and Landete areas, which were situated further away. This contention is in agreement with recent studies which demonstrate that an important thermal event took place during Late Triassic–Early Jurassic times in the Iberian Peninsula.

Late Paleozoic reefs and their significance for tectonics and oil-gas exploration in the Hinggan-Inner Mongolia area

Many reefs of the Late Paleozoic have been discovered recently in the Hinggan-Inner Mongolia area. These reefs clearly are geographically extensive, and possess distinctive features and well-developed reef-facies. They have been found to contain five reef-building communities and were constructed in four periods. Colonial coral-algal reefs at Aohan and Chifeng represent a warm shallow-sea in the Carboniferous. Different reefs in the Xiwu Banner were formed in three periods: early Late Carboniferous, late Late Carboniferous and Early Permian. These reefs were built in warm sea conditions. Their buildup types include colonial coral frameworks, algae-buildings and lime-mud mounds. Bryozoan reefs in the Zhalaite and Dongwu banners were built in the late Middle Permian and thrived in a cold shallow-sea. All reefs grew independently on two kinds of sedimentary platforms, carbonate and carbonate-clastic mixed platforms. Four reef-forming periods occurred later from south to north, along a collisional course between the North China Plate and the Siberian Plate. These reefs can be arranged into three ‘reef-links’ or reef zones that extend along plate margins. Among these, the Aohan-Chifeng reef-link indicates a northern margin of the North China Plate, the Zhalaite-Dongwu reef-link marks a southern margin of the Siberian Plate, and the Xiwu-Beishan reef-link reflects the former existence of some inter-plates. The strata of each reef-facies are thick and contain rich asphalt deposits. Overlapping and heteropic layers are very thick and contain dark oil/gas-rich horizons; TOC analyses verify that most of these are good hydrocarbon source rocks. This study shows that the study area is an excellent candidate for oil-gas exploration.

Late Middle Permian (Capitanian) Foraminifers from the Uppermost Part of the Taishaku Limestone, Akiyoshi Terrane, Japan

Forty-four species assignable to 32 genera of late Middle Permian (Capitanian) foraminifers are distinguished from Lepidolina limestone and microbial limestone of the uppermost part of the Taishaku Limestone, northeastern part of Hiroshima Prefecture, Japan. The microbial limestone contains Kahlerina taishakuensis sp. nov. enclosing problematic microfossils within their tests and is taxonomically less diversified than the Lepidolina limestone. Faunal composition of nonfusuline foraminifers is clarified in the Lepidolina Zone of the Akiyoshi Terrane for the first time. In addition to the new species, seven species are systematically described. They are Codonofusiella sp. cf. C. ashioensis Kobayashi, Chusenella otai (Nogami), Parafusulina sp., Lepidolina multiseptata (Deprat), Hemigordiopsis renzi Reichel, Baisalina ovata Han, and Partisania typica Sosnina. Taxonomic comments are given on Kahlerina and Hemigordiopsis.

Lake deposits of moderate salinity as sensitive indicators of lake level fluctuations: Example from the Upper Rotliegend saline lake (Middle–Late Permian, Northeast Germany)

The Rotliegend saline lake periodically covered wide areas of the Southern Permian Basin in Northwest Europe during the Permian. The sedimentology, mineralogy and geochemistry of lake deposits were studied to document very high frequency lake level fluctuations and to evaluate their triggers. Increased precipitation and marine ingressions into the basin resulted in lake extension. Increased run-off is documented by intercalated fluvial deposits in low-salinity deposits of the lake. Because lake deposits reflect mainly deposition in relatively wet climate phases, they are not correlatable to halite deposits in other basin areas. Decreased precipitation is followed by shrinkage of the lake, desiccation at its margins, and higher lake salinity due to concentration of the brine. Carbonate and anhydrite contents of lake deposits increased considerably before the areas fell dry, but halite is not preserved in the study area. Falling lake level is also reflected by the occurrence of wave ripples, reflecting decreased water depth and finally by desiccation and formation of evaporite crusts. Not only the mineralogical content, but also the colour of lake claystones changes with varying salinity. Anhydrite- and carbonate-free red claystones were replaced by violet to green and grey anhydritic and calcareous claystone or marls with increasing salinity. The amount of boron adsorbed on illite also corresponds to changes in salinity and can therefore be used as a palaeosalinity indicator. Rare earth element concentrations within lake deposits do not reflect variations in salinity but different palaeogeographical settings. Marine ingressions into the lake are neither reflected by the amount of boron adsorbed onto illite nor by rare earth element contents of the lake deposits. Highly saline deposits are partly characterised by intensive deformation, which can be interpreted as seismites or dissolution breccias.

The evolution of Paleozoic vascular land plant diversity of South China

Data of Paleozoic and some Early Triassic vascular land plant fossils from South China are synthetically analyzed, revealing evolutionary characteristics of Paleozoic vascular land plant diversity. Vascular land plant diversity keeps increasing in the Paleozoic as a whole. The Silurian witnessed the earliest evolution and initial diversification of land plants. From the Early Devonian to the Early Carboniferous (Mississippian), the great development, diversification, and differentiation really occurred in vascular land plants, with fluctuations of diversity, rapid replacement of the plant types, and an all-out takeover of terrestrial ecological niches. From the Early Permian, land plant diversity dramatically increased, and reached a climax in the Middle-Late Permian. Comparisons between late Paleozoic marine and terrestrial biodiversity reveal co-evolution of the late Paleozoic animals and plants as well as the individual evolutionary patterns of sea/land ecosystems. Vascular land plant diversity dramatically declined in the Frasnian as a result of the F/F event, and the end-Permian mass extinctions completely turned over the phytogroups.

The Permian–Triassic transition and the onset of Mesozoic sedimentation at the northwestern peri-Tethyan domain scale: Palaeogeographic maps and geodynamic implications

The main aim of this paper is to review Middle Permian through Middle Triassic continental successions in European. Secondly, areas of Middle–Late Permian sedimentation, the Permian–Triassic Boundary (PTB) and the onset of Triassic sedimentation at the scale of the westernmost peri-Tethyan domain are defined in order to construct palaeogeographic maps of the area and to discuss the impact of tectonics, climate and sediment supply on the preservation of continental sediment.At the scale of the western European peri-Tethyan basins, the Upper Permian is characterised by a general progradational pattern from playa-lake or floodplain to fluvial environments. In the northern Variscan Belt domain, areas of sedimentation were either isolated or connected to the large basin, which was occupied by the Zechstein Sea. In the southern Variscan Belt, during the Late Permian, either isolated endoreic basins occurred, with palaeocurrent directions indicating local sources, or basins underwent erosion and/or there was no deposition. These basins were not connected with the Tethys Ocean, which could be explained by a high border formed by Corsica–Sardinia palaeorelief and even parts of the Kabilia microplate. The palaeoflora and sedimentary environments suggest warm and semi-arid climatic conditions.At the scale of the whole study area, an unconformity (more or less angular) is observed almost everywhere between deposits of the Upper Permian and Triassic, except in the central part of the Germanic Basin. The sedimentation gap is more developed in the southern area where, in some basins, Upper Permian sediment does not occur. The large sedimentary supply, erosion and/or lack of deposition during the Late Permian, as well as the variable palaeocurrent direction pattern between the Middle–Late Permian and the Early Triassic indicate a period of relief rejuvenation during the Late Permian. During the Induan, all the intra-belt basins were under erosion and sediment was only preserved in the extra-belt domains (the northern and extreme southern domains). In the northern domain (the central part of the Germanic Basin), sediment was preserved under the same climatic conditions as during the latest Permian, whereas in the extreme southern domain, it was probably preserved in the Tethys Ocean, implying a large amount of detrital components entering the marine waters. Mesozoic sedimentation began in the early Olenekian; the ephemeral fluvial systems indicate arid climatic conditions during this period. Three distinct areas of sedimentation occur: a northern and southern domain, separated by an intra-belt domain. The latter accumulated sediments during the Early–Middle Permian and experienced erosion and/or no-deposition conditions between the Middle–Late Permian and the beginning of Mesozoic sedimentation, dated as Anisian to Hettangian. At the top of the Lower Triassic, another tectonically induced, more or less angular unconformity is observed: the Hardegsen unconformity, which is dated as intra-Spathian and is especially found in the North European basins. This tectonic activity created new source areas and a new fluvial style, with marine influences at the distal part of the systems. During the Anisian and Ladinian, continental sedimentation was characterised by a retrogradational trend. In other words, the fluvial system evolved into fluvio-marine environments, attesting to a direct influence of the Tethys Ocean in the southern and northern domains. Both at the end of the Olenekian (Spathian) and during the Anisian, the presence of palaeosols, micro- and macrofloras indicate less arid conditions throughout this domain.

The Guadalupian (Permian) Kamura event in European Tethys

In order to document paleoenvironmental conditions of the equatorial western Paleo-Tethys during the late Middle Permian prior to the end-Guadalupian mass extinction, chemostratigraphic analysis using stable carbon isotopes was conducted for the Guadalupian rocks at Brusane in the Velebit Mtn., central Croatia. By analyzing 72 carbonate samples of the Capitanian (Upper Guadalupian) Velebit Formation, we found an interval with unusually high δ 13C carb values (+ 4 to + 6‰) in the ca. 150 m-thick Yabeina (fusuline) Zone. The present find clarifies that the primary productivity and burial rate into the sediments were considerably high during the Capitanian in westernmost Paleo-Tethys. This chemostratigraphic signal is properly correlated with the “Kamura event” detected in a mid-Panthalassan paleo-atoll limestone in Japan. The present results identify the Capitanian “Kamura event” for the first time in European Paleo-Tethys on the opposite side of the globe from the mid-Panthalassan paleo-seamount, and prove the global context of the event as well as its utility in chemostratigraphic correlation. In order to enhance bioproductivity on a global scale, the increase in nutrient supply is inevitable. In addition to riverine run-off from Pangea, active oceanic circulation, in particular upwelling of deep-sea water enriched in nutrients, was likely vital both in Panthalassa and Paleo-Tethys. The extinction of some Guadalupian fauna, in particular photosymbiotic community (large-tested fusulines, large bivalves, rugose corals), was likely related to a temporary cooling coupled with eutrophication in low-latitude shallow marine environments of Paleo-Tethys and Panthalassa.

The youngest rostroconch mollusc from North America, Minycardita capitanensis n. sp.

Rostroconchs are an extinct class of mollusc that lived worldwide through most or all of the Paleozoic Era (Runnegar 1978). They were most diverse in the early Paleozoic (Pojeta 1985), perhaps due to a lower rate of evolution in the rostroconch clade that survived the end-Ordovician mass extinction event (Wagner 1997). Rostroconchs have a univalved larval shell and a pseudo-bivalved adult shell. Their ecology appears to have ranged from infaunal to rarely epifaunal, and from deposit to suspension feeding (Pojeta et al. 1972, Pojeta & Runnegar 1976, Runnegar 1978, Pojeta 1987). A single but well-preserved, essentially complete rostroconch specimen was recovered from the region surrounded by the famous Capitan Reef of the Permian of West Texas (Newell et al. 1953). In particular, the specimen is from the upper scaphopod bed of the Reef Trail Member of the Bell Canyon Formation exposed in the Guadalupe Mountains National Park (Rigby & Bell 2005: fig. 2). The fusulinid biostratigraphic zonal indicator Paraboultonia splendens Skinner & Wilde, 1954 occurs both below the upper scaphopod bed and above it, indicating that this horizon was deposited during the latest Guadalupian (late middle Permian) (Rigby & Bell 2006), and thus is the youngest known deposit in North America to contain a rostroconch. Most known Permian rostroconchs have been recovered from rocks in North America, and only one occurrence stands out as clearly younger than this one: Pseudoconocardium Zavodowsky, 1960 from the Late Permian of Siberia, a large rostroconch that differs significantly in shape and ornamentation from rostroconchs of the late Paleozoic in North America (Hoare et al. 2002). Permian rostroconchs are rare, having been described from only sixteen localities worldwide (listed in Hoare & Plas 2003). In contrast, rostroconchs were relatively abundant during the preceding Pennsylvanian (Hoare et al. 2002). Thus the occurrence described herein represents the youngest known record of the North American rostroconch lineages, and is one of the last snapshots of a major molluscan clade.

The Effect of Emeishan Supper Mantle Plume on the Thermal Evolution of Hydrocarbon Source Rocks in the Sichuan Basin

AbstractBoth the structural evolution and thermal history of the Middle ‐ Late Permian Sichuan Basin are closely related to activity of the Emeishan Supper Mantle Plume (ESMP). The ESMP played an important role in the thermal evolution of the pre‐Middle Permian hydrocarbon source rocks in the southwestern part of the Sichuan basin. On the basis of reconstructed thermal history of the Sichuan basin, based on vitrinite reflectance (Ro) from boreholes in the basin, using a paleo‐heat flow method, the effect of the ESMP on the evolution of the pre‐Middle Permian source rocks is studied. The results show that in the southwestern part of the Sichuan Basin (the intermediate zone of the ESMP) the organic matter of the Paleozoic source rocks became mature in middle Late Permian. This indicates that the thermal evolution of the Paleozoic source rocks was strongly affected by the ESMP. In more detail, in the region close to the ESMP, the source rocks of lower Permian were heated to peak maturity (maximum Ro > 3%) at around 260 Ma and later there was no secondary hydrocarbon generation. However, in the regions far away from the ESMP, secondary Mesozoic hydrocarbon generation of the source rocks existed. The thermal evolution of the Mesozoic source rocks was related with Mesozoic foreland basin evolutionburial history and subsequent regional denudation of the basin, rather than the ESMP. Therefore, except in the regions far away from the ESMP, the prospect of oil and gas from Paleozoic source rocks is unfavorable.

Radiolarian and fusuline fossils from oceanic rocks in the Ashio Terrane of the Kambara Massif, Niigata Prefecture, Southwest Japan

Radiolarian and fusuline fossils were discovered respectively from chert and limestone blocks in the Ashio Terrane of the Kambara Massif, Southwest Japan. Radiolarians in gray bedded chert indicate an age of late Middle Permian (Capitanian) to early Late Permian (Wuchiapingian), and those in black massive chert indicate a latest Permian (Changhsingian) age. This is the first report of Late Permian oceanic rocks in the Kambara Massif. Fusulines in a piece of limestone float indicate a latest Carboniferous (Kasimovian and late Gzhelian) age. This limestone is probably the same as that reported in a previous study, broadly inferred to be Late Carboniferous to Early Permian in age. Therefore, the age of the limestone is now well constrained. These fossil data are important in reconstructing the oceanic plate stratigraphy of the Ashio Terrane of the Kambara Massif.

Effects of Middle–Late Permian sea-level changes and mass extinction on the formation of the Tieqiao skeletal mound in the Laibin area, South China

A skeletal mound is described for first time from a Middle–Late Permian succession that contains the Guadalupian–Lopingian (G/L) boundary at the Tieqiao section in the Laibin area, Guangxi Province, South China. The Tieqiao mound grew on a deep-water, south-facing carbonate ramp during the late Middle Permian. The mound features a range of grainstone–packstone to rudstone–floatstone facies together with sponge boundstone facies. Both sponges and algae acted as frame builders which colonised skeletal debris on the ramp and initiated mound growth. Diverse benthic biota comprising mound dwellers and constructors proliferated in the Tieqiao mound complex. The water depth changes recorded in the Tieqiao mound successions reflect the refined trajectory of global sea-level changes during the great regression at the end of the Middle Permian. The timing of sea-level lowstand coincides with disappearance of the Jinogondella granti conodont zone at Tieqiao. The change to sea-level rise pre-dated the G/L boundary. Growth and demise of the mound is interpreted to have been controlled by changes in sea-level. Abrupt disappearance of both body fossils and fossil fragments of leading fossil groups at Tieqiao is interpreted as the result of the G/L mass extinction rather than environmental change. The potential extinction horizon is ∼30 cm above the G/L boundary at Tieqiao and also records a rise in sea-level. The regional fall in sea-level destroyed the Tieqiao mound, but the G/L crisis halted redevelopment of the mound in the earliest Late Permian. Most mound builders suffered severely the Lazarus effect of the G/L mass extinction.