Late Middle Permian Research Articles

Effects of the Emeishan large igneous province (ELIP) and coastal upwelling on paleoenvironment and organic matter accumulation during the Middle Permian (Capitanian), South China

The late Middle Permian (Capitanian) was characterized by many global geological, biotic and environmental events, along with the widespread deposition of organic-rich strata. Elucidating the relationships between organic matter (OM) accumulation and critical geological events is of significance for Earth system science and petroleum resource geology, but the mechanism remains unclear. To fill the knowledge gap, this study investigated the Gufeng Formation in the middle Yangtze region of South China to examine the links between OM accumulation and geological events, e.g., the Emeishan large igneous province (ELIP) and coastal upwelling. Our results show that the Gufeng Formation exhibits significant OM enrichment, with an average total organic carbon (TOC) content of 8.34 wt%. The paleoceanographic conditions went through three stages during the Capitanian: the early–middle stage of high primary productivity and anoxic–sulfidic conditions; the middle stage of moderate productivity and anoxic conditions; and the late stage of low productivity and dysoxic conditions due to weakened upwelling and a global sea-level fall. OM accumulation was influenced mainly by upwelling-induced high productivity and anoxic conditions related to the oxygen minimum zone (OMZ), with a secondary control of carbonate dilution. The ELIP possibly had a limited contribution to high TOC contents. In South China, the Gufeng and uppermost Maokou formations were marked by high OM contents (average TOC > 3 wt%; maximum = 40 wt%), resulting primarily from widespread coastal upwelling along the eastern margin of the Paleo-Tethys Ocean during the Middle Permian. ELIP volcanism mainly triggered rapid climate warming during the late Capitanian and had a regional and variable effect on OM enrichment for different regions in South China.

Metal remobilization at the Nibao gold deposit in Youjiang basin, SW China: Implications from mineral texture, trace element and sulfur isotope compositions of sulfides and TiO2 polymorphs

Multistage mineralization overprinting is important for the formation of giant hydrothermal gold deposits. The Youjiang basin in SW China has undergone at least three major deformation phases in the Mesozoic, but their relationship with the large-scale gold accumulation in the region remains enigmatic. Here, we study the large Nibao gold deposit (reserve > 70 t Au) in the northern part of the basin, which has both fault-controlled and stratabound orebodies. We identified a pre-ore stage and syn-ore stage including four tectono-hydrothermal (T-H) substages (i.e., T-H stage 1, 2, 3 and 4) for the local mineralization at Nibao. The pre-ore stage is dominated by coarse-grained pyrite coexisting with TiO2 polymorphs in the Middle-Late Permian basaltic rocks. The T-H substage 1 is characterized in that the sedimentary pyrites are brecciated in bedding-parallel faults. Fluorination and silicification occur in the T-H substage 2, which is re-brecciated at the T-H substage 3 forming the highest gold grade ore in high-angle thrust fault. The T-H substage 4 presents as fault reactivation within minor calcite and pyrite deposition. Mineralogy and in-situ trace element analyses reveal that mineral dissolution and reprecipitation (incl. dolomite, auriferous pyrite and TiO2 polymorphs) is ubiquitous during the multistage tectono-hydrothermal process, and the continuous alteration overprinting may have promoted gold accumulation. This replacement process of different generations of auriferous pyrite is also recorded by their inherited sulfur isotopes, giving a narrow δ34S (−3.1 to + 2.1 ‰) range. Anatase is the main accessory phase of TiO2 polymorphs, as identified with LA-ICP-MS trace element and laser Raman spectroscopic analyses. Moreover, the anatase can been divided into two types (type-I and II) based on their texture, alteration and chemistry. The type-I anatase commonly occurring in the stratabound ore is characterized by higher Zr (mean 1,730 ppm), V (mean 1,412 ppm), and Cr (mean 110 ppm) contents than type-II that coexists with zoned pyrite in the fault-controlled ore (mean 26 ppm, 187 ppm, and 38 ppm, respectively). Additionally, W (mean 636 ppm) and Mg (10,021 ppm) in type-II are much higher than type-I ones (mean 135 ppm W and 476 Mg). These features show that the sedimentary-stage Zr-V-Cr-rich type-I anatase was dissolved via fluid metasomatism, and reprecipitated as the hydrothermal-stage W-Mg-rich and Zr-poor anatase, with gold gradually enriched. Besides, the anatase phase of TiO2 polymorphs also indicates that the Nibao gold deposit was formed under low pressure–temperature condition. Overall, we propose that the Nibao is a Carlin-type gold deposit, dominated by multistage tectono-hydrothermal events.

Microfacies and palaeoenvironments of late Cisuralian and Guadalupian (Early to Middle Permian) alatoconchid-bearing limestone in Loei fold belt, Indochina Terrane

This study presents the first record of Early Permian alatoconchid bivalves from Thailand, the Erawan section, in the north of Loei fold belt with prolific fusulines in association with gastropods, and brachiopods. Fusuline taxa are dominated by Pseudofusulina sp. with Darvasites sp., Staffella cf. labanalensis, Staffella sp., Nankinella sp., Neofusulinella sp., Schubertella sp., Pamirina darvasica, Pseudoendothyra sp. and others, indicating an Artinskian age. Fusuline wackestone with common, well-preserved smaller foraminifers, Pseudovermiporella sp. and ostracods indicates a restricted lagoon environment with low to moderate water circulation. These fossils, along with well-preserved, articulated alatoconchids in life-position, suggest the autochthonous nature of the deposits in an intertidal environment.In the central part of the fold belt, the Pak Chong section exhibits intervals of alatoconchid biostromes and coquinites. Carbonate build-ups of the alatoconchid biostromes with gregarious bivalves, in life-position embedded in a micritic wackestone matrix, suggest their preferred life habit and environment. The bivalve coquinites containing packed bivalve shells and fragments, however, indicate a high-energy event. This rock fabric along with common fusuline storm sheets suggests occasional storm events in a restricted, with moderate water circulation to open lagoon environment. Fusulines are predominated by staffellids and others including Staffella sphaerica, Staffella sp., Sphaerulina croatica, Pisolina subsphaerica, Nankinella sp., Neoschwagerina simplex, Presumatrina sp., Afghanella sp. and others, indicating a Wordian (Middle Permian) age.In the southern portion of the fold belt along the Thai-Cambodian border, the Khao Taa Ngog section contains limestone with alatoconchid shells with massive rugose corals which formed local carbonate build-ups in high-energy open platform environments. Poorly-sorted bioclasts with common fusuline tests, shell fragments and coated grains suggest an open marine, lagoon, back reef environment. The occurrence of a fusuline assemblage including Neoschwagerina sp., Yabeina sp., Lepidolina sp., Codonofusiella sp., Verbeekina verbeeki and Chusenella sp. indicates the Capitanian (late Middle Permian) age.

Permian tectonic evolution and continental accretion in the eastern Central Asian Orogenic Belt: A perspective from the intrusive rocks

The tectonic evolution and history of continental accretion of the eastern Central Asian Orogenic Belt (CAOB) are not yet fully understood. In this study, we investigate Permian intrusive rocks from the Jiamusi Block of the eastern CAOB to constrain the tectonic evolution and continental accretion of this region during the late-stage evolution of the Paleo-Asian Ocean. Our new data show that Early Permian gabbro-diorites were derived from the partial melting of depleted mantle metasomatized by oceanic-slab-released fluids. Middle Permian adakitic granites have low Na2O and MgO and high K2O contents, indicating a thickened-lower-crust source. Late Permian S-type granites were derived from the partial melting of continental crust. A compilation of the available geochronological data for Permian intrusive rocks (including adakitic and A-, S-, and I-type granites and mafic rocks) from the eastern CAOB reveals that the A-type granites formed mainly during the Early–Middle Permian, S-type and adakitic granites mostly during the Middle–Late Permian, and I-type granites and mantle-derived mafic rocks throughout the Permian. The A-type granites, which are proposed to have been sourced from thinned continental crust, indicate an extensional setting in the eastern CAOB during the Early Permian. The Middle–Late Permian adakitic granites imply a thickened continental crust, which indicates a compressional setting. Therefore, the eastern CAOB underwent a transition from extension to compression during the Middle Permian, which was probably triggered by the late-stage subduction of Paleo-Asian oceanic crust. Considering the petrogenesis of the intrusive rocks and inferred regional tectonic evolution of the eastern CAOB, we propose that vertical underplating of mantle- and oceanic-slab-derived magmas contributed the materials for continental crust accretion.

Permian post-orogenic terrestrial successions in the western and northern peripheral orogens of the Junggar Basin: Records of sedimentary provenance, paleogeographic and tectonic changes

The Permian terrestrial successions were deposited in peripheral orogens of the main Junggar Basin, including the West Junggar and Chinese Altai orogens. These successions probably marked the termination of the Paleozoic orogeny in the SW Central Asian Orogenic Belt and document paleogeographic and tectonic changes during that time. However, comprehensive research of these successions is still lacking. This study investigated representative sections and outcrops of Permian successions in West Junggar and Chinese Altai, and we present a detailed sedimentological comparison in the specific chronological framework according to new zircon U-Pb ages of syn-depositional volcanics. This comparison shows that the Lower Permian successions consist of almost equal amounts of sedimentary rocks (46–56%), characterized by fluvial (meandering river-dominated)-deltaic and lacustrine facies, and volcanic rocks (44–54%). By contrast, the Middle–Upper Permian is dominated by alluvial facies (>79%) with highly reduced fluvial-deltaic and lacustrine facies. Furthermore, detrital modes and detrital zircon dating were applied to sandstones from four selected areas for provenance analysis. As a result, two major provenances were detected by detrital zircon ages, including the syn-depositional volcanics and granitoids (40–65%) and the Devonian–Early Carboniferous subduction-related plutons and arc volcano-sedimentary rocks (31–51%). Samples in Tarbagatay received a certain contribution from the Early Paleozoic arcs, and materials from the metamorphic basement in Chinese Altai localized in the vicinity and northernmost West Junggar. In summary, the Early Permian paleogeographic pattern of West Junggar is proposed as a series of small-scale fluvial plains and lacustrine basins that were separated by syn-depositional volcanoes and uplifted Paleozoic orogenic units under a tectonic setting of active rifting. The great shrinkage of sedimentation and coarsening of deposits during the Middle–Late Permian was triggered by intracontinental deformation rather than regional climate change.

Sedimentary Facies, Paleogeography, and Depositional Models of the Middle–Late Permian in the Sichuan Basin, Southwest China

This study focuses on the analysis of the sedimentary facies of the Middle–Late Permian, including the Qixia, Maokou, Wujiaoping/Longtan, and Changxing/Dalong Formations, in the Sichuan Basin, southwest China. Integrating drilling data and field outcrop data, various sedimentary facies indicators were employed to define eight sedimentary facies types in the Sichuan Basin during the Middle–Late Permian, namely, mixed tidal flat, tidal flat, restricted platform, open platform, platform margin, slope, basin, and volcanic facies. Detailed facies analysis was conducted on selected well logs, and sedimentary facies distribution maps were compiled for different time intervals, establishing depositional models. During the Qixia to Maokou stages, an extensive open platform was developed in the Sichuan Basin, accompanied by shallow intra-platform shoals. Towards the west along the Dayi–Ya’an line, platform margins were developed, followed by slope facies and basin facies in a northwest direction. During the Changxing stage, the Kaijiang–Liangping fault block subsided, forming the “Kaijiang-Liangping” paleochannel, which controls reef–shoal deposition in the region. This study provides comprehensive insights into the sedimentary facies characteristics and depositional environments of the Middle–Late Permian in the Sichuan Basin, contributing to the understanding of the regional sedimentary history and geological evolution.

First record of the rare dicynodont Colobodectes from the southern Karoo Basin of South Africa has implications for middle permian continental biostratigraphy

Colobodectes is a dicynodont therapsid known from five partial skulls. All are from the western and north-western part of the Beaufort Group in the Karoo Basin and occur in close stratigraphic proximity to the contact between the Ecca and Beaufort groups. Although the provenance of all specimens is near the base of the late middle Permian (Guadalupian) Abrahamskraal Formation, their precise age is uncertain as a result of diachroneity of the base of the formation and the absence of index taxa to correlate this horizon with the biostratigraphy established in the southern Karoo Basin. Here we describe an additional specimen of Colobodectes recently discovered from a locality low in the Abrahamskraal Formation in the southern Karoo Basin. Given the unusual associated fauna at this locality, the occurrence of Colobodectes provides an interesting correlation between the base of the Abrahamskraal Formation in the Northern Cape Province and lower Abrahamskraal Formation in the southwestern part of the basin. It occurs at a similar level to the dicynodont Lanthanostegus, adds an additional species to the transition between the Eodicynodon and Tapinocephalus assemblage zones (AZ), and provides a link between the basal Beaufort rocks in the Northern and Eastern Cape provinces. This supports earlier work proposing that the Eodicynodon AZ is present only on the southwestern side of the Karoo Basin and that the transition from a marine to continental depositional environment occurred later toward the North and East.

Guadalupian–Lopingian (Middle–Late Permian) radiolarians from clastic rocks and zircon U–Pb ages of intercalated tuff and tuffaceous sandstone on Sado Island, central Japan

We investigated Permian strata in the Ota area of the Kosado Hills, Sado Island, central Japan, and their depositional ages were determined based on radiolarian biostratigraphy and zircon U–Pb dating. We also focused on the geology of the region and its lithologic correlation with other geological units in the Inner Zone of Southwest Japan. The radiolarian analysis identified the presence of Follicucullus porrectus and F. dilatatus in mudstone exposed on the coastline of Ota, indicating a middle–late Capitanian to early Changhsingian age. Mudstone exposed along the forest road in the Ota area contained Cariver charveti, suggesting a late Capitanian–early Changhsingian age. Zircon U–Pb dating of the tuff layer intercalated within the Follicucullus-bearing mudstone yielded a weighted-mean age of 259.9 ± 2.0 Ma, corresponding to a Capitanian–Wuchiapingian age. The tuffaceous sandstone interbedded with mudstone containing C. charveti yielded a weighted-mean age of 264.1 ± 6.3 Ma, which covers the Roadian to Wuchiapingian ages. The youngest model peak age (256.6 ± 2.6 Ma; Wuchiapingian) provides the most reliable estimate of the maximum depositional age. The Paleozoic strata in the Kosado Hills have previously been correlated with the Ultra-Tamba and Maizuru belts in Southwest Japan based on fossil occurrences. Our findings indicate that the Permian rocks in the Kosado Hills exhibit differences in lithology from those in the Ultra-Tamba belt but share similarities with the upper Guadalupian–Lopingian strata in the Maizuru belt.

Tectonic evolution of the Middle-Late Permian orogenic belt in the eastern part of the CAOB: Implications from the magmatism in the Changchun-Kaiyuan area

AbstractVarious magmatisms during the subduction-collision process are crucial to reveal the long-term tectonic evolution of the eastern Central Asian Orogenic Belt. In this paper, we present major and trace elements of whole-rock, zircon U-Pb dating and Hf isotope of the Shanmen pluton. Results imply that the Shanmen pluton consists of quartz diorite and mylonitic granite, with zircon U-Pb ages of 263.7–259.6 Ma. The studied quartz diorite contains high Sr/Y (51.19–90.87) and (La/Yb)N (7.82–13.62) ratios, and belongs to adakitic rocks. Coupled with the positive εHf(t) values of +5.71 to +12.8 with no obvious Eu anomaly, we propose that quartz diorite is the product of the interaction between different degrees of slab melt and the overlying mantle wedge. In contrast, the mylonitic granite has lower MgO (0.28 wt% – 0.47 wt%) contents and positive εHf(t) values of +7.79 to +10.15, indicating an affinity with I-type granite originated by partial melting of the intermediate-basic lower crust. The geochemical characteristics and lithological assemblages, along with the Permian magmatic rocks in the Changchun-Kaiyuan area displaying arc rocks affinity, propose their formation is related to the southward subduction of the Paleo-Asian Ocean (PAO). Based on this study and previous evidence, we lean towards adopting a middle-late Permian slab break-off model, wherein the PAO did not close until the late Permian.

Petroleum geology and sub-source hydrocarbon accumulation of Permian reservoirs in Jinan Sag, eastern Junggar Basin, NW China

According to the latest drilling and the analysis of the burial history, source rock evolution history and hydrocarbon accumulation history, the sub-source hydrocarbon accumulation characteristics of the Permian reservoirs in the Jinan Sag, eastern Junggar Basin, are clarified, and the hydrocarbon accumulation model of these reservoirs is established. The results are obtained in four aspects. First, the main body of the thick salified lake basin source rocks in the Lucaogou Formation has reached the mature stage with abundant resource base. Large-scale reservoirs are developed in the Jingjingzigou, Wutonggou and Lucaogou formations. Vertically, there are multiple sets of good regional seals, the source-reservoir-caprock assemblage is good, and there are three reservoir-forming assemblages: sub-source, intra-source and above-source. Second, dissolution, hydrocarbon charging and pore-preserving effect, and presence of chlorite film effectively increase the sub-source pore space. Oil charging is earlier than the time when the reservoir becomes densified, which improves the efficiency of hydrocarbon accumulation. Third, buoyancy and source-reservoir pressure difference together constitute the driving force of oil charging, and the micro-faults within the formation give the advantage of “source-reservoir lateral docking” under the source rock. Microfractures can be critical channels for efficient seepage and continuous charging of oil in different periods. Fourth, the Jingjingzigou Formation experienced three periods of oil accumulation in the Middle–Late Permian, Middle–Late Jurassic and Late Neogene, with the characteristics of long-distance migration and accumulation in early stage, mixed charging and accumulation in middle stage and short-distance migration and high-position accumulation in late stage. The discovery and theoretical understanding of the Permian reservoirs in the Jinan Sag reveal that the thrust belt has good conditions for forming large reservoirs, and it is promising for exploration. The study results are of guidance and reference significance for oil and gas exploration in the Jinan Sag and other geologically similar areas.

Global oceanic anoxia linked with the Capitanian (Middle Permian) marine mass extinction

The timing and causation of the Capitanian (late Middle Permian) biocrisis remain controversial. Here, a detailed uranium-isotopic (δ238U) profile was generated for the mid-Capitanian to lower Wuchiapingian of the Penglaitan section (the Guadalupian/Lopingian Permian global stratotype) in South China for the purpose of investigating relationships between the biocrisis and coeval oceanic anoxic events (OAEs). Negative δ238U excursions indicate two distinct OAEs, a mid-Capitanian (OAE-C1) and an end-Capitanian (OAE-C2) event. Mass balance modeling shows that the anoxic sink of uranium (Fanox; i.e., the fraction of the total U burial flux) and anoxic seafloor area (Farea; i.e., the fraction of total seafloor area) increased during each OAE. A dynamic mass balance model yields increases of Fanox from <30% to >60% and Farea from ∼1% to ∼4-7% during each OAE. These two OAEs coincided with two extinction episodes during the Capitanian biocrisis, supporting a causal relationship between oceanic anoxia and mass extinction during the Middle Permian. The most likely driver of middle to late Capitanian global warming and oceanic anoxia was episodic magmatism of the Emeishan Large Igneous Province.

Depositional response to the Emeishan mantle plume: evidence from the eastern Sichuan Basin, South China

ABSTRACT The Emeishan large igneous province (ELIP) is among the prominent large igneous provinces in the world and has been associated with mantle plume activity. In this study we investigated the impact of the Emeishan mantle plume on generating the sedimentary rock suites of the eastern Sichuan Basin. We present petrology, detrital zircon U – Pb ages, trace elements, and Hf isotopic compositions of the Middle-Late Permian sedimentary sequences in the Huayingshan region to constrain the provenance and characterize the depositional response to the Emeishan mantle plume activity. The detrital zircon U – Pb ages of the Middle Permian Maokou Formation indicate that terrigenous detritus was mainly sourced from the Kangdian paleoland in the southwestern margin of South China. Detrital zircon grains from the bottom of the Late Permian Longtan Formation yield a lower intercept age of 257 ± 28 Ma, interpreted as the contemporaneous metamorphism related to the ELIP magma. The detrital zircon U – Pb ages of the middle part of the Longtan Formation are characterized by unimodal age spectra with a peak at 259 Ma. Provenance analysis indicates that the Longtan Formation was mainly sourced from the Emeishan volcanic rocks in the Huayingshan region. We propose that the Kangdian paleohigh may have been regionally uplifted as the result of the pre-eruption rise of the Emeishan mantle plume in the late Middle Permian. Moreover, this paleohigh was translated into a denuded zone and provided voluminous detritus into the eastern Sichuan Basin. In the early Late Permian, the ELIP magmas upwelled and outpoured from the Huayingshan fault, and flowed past the peripheral rocks to the low terrain in the Huayingshan region. The ELIP volcanic rocks in the Huayingshan region underwent intense post-eruption erosion, resulting in the deposition of voluminous volcanic detritus in the eastern Sichuan Basin.

A new Caloneurodea family (Insecta, Archaeorthoptera) increases the insect palaeodiversity of the middle Permian Salagou Formation (southern France)

A new genus and species of the archaeorthopteran order Caloneurodea are described and illustrated from the Salagou Formation (France) as Lodevogramma pumilia gen. et sp. nov. The particular wing venation of this species precludes its placement within one of the already described families of Caloneurodea. Consequently, the family Lodevogrammatidae fam. nov. is created to accommodate this specimen. A detailed comparison of the new species with other Caloneurodea is provided. This new species differs from all other Caloneurodea because it has: petiolate wings; the area between C and R/RA is very narrow; vein RA ends near the wing apex; vein RP has two branches; the fork of CuP basad the base of M; and two very short anal veins are present. This new species increases the diversity of Caloneurodea in the Salagou Formation and provides additional information on the diversity of the order around the late Capitanian extinction. We compared the diversity of Caloneurodea with that of Megasecoptera, another order with a similar history between the Carboniferous and the Permian, and hypothesized that the decrease in the size of both groups could be an indicator of their declines, possibly related to floral changes, following a pattern similar to that of Permian tetrapods. The decline of Caloneurodea could also be related to the diversification of the Orthoptera during the middle–late Permian. http://zoobank.org/urn:lsid:zoobank.org:pub:1A14DF89-0F25-4105-B087-DC79D644728F

Evolution and driving mechanisms of water circulation during the late Paleozoic to early Mesozoic

<p indent="0mm">Water circulation plays a crucial role in the Earth’s systems, linking the atmosphere, hydrosphere, lithosphere, and biosphere. During the Paleozoic-Mesozoic transition, climatic and environmental conditions turned into crises, caused by a sudden and serious global warming, accompanied by the largest known extinction event of all time. Several studies have been conducted to discover the causes of this notable climate change. Nevertheless, the evolution of water circulation processes during the Paleozoic-Mesozoic transition is still unclear. Several lithologic indicators present in paleoclimate records have been described over the last few decades. Based on these data, we defined climate zones and calculated their area values using Thiessen polygons and Geographic Information System technology to visualize climate evolution during the Paleozoic-Mesozoic transition. Results of a few of the climate simulations showed changes in precipitation and the amplitudes of the inter-tropical convergence zone (ITCZ) seasonal migration. The results showed several changes in water circulation during the late Paleozoic to early Mesozoic. (1) The climate zones reconstructed by sedimentary and paleontological records showed a remarkable arid expansion. The distribution area of evaporites began to expand in the Middle to Late Permian and reached a peak in the Early Triassic, returned to Middle-Late Permian levels in the Middle Triassic, and thereafter continued to narrow during the Late Triassic to Early Jurassic. (2) Global precipitation was higher during the Late Carboniferous and Early Jurassic and lower in the Middle to Late Permian and Early Triassic. Such a “V” shape represents considerable swing. (3) The assembly of Pangea might have led to “giant land surface winds” in Pangaea and “trans-equatorial winds” in the Tethys region, resulting in a global “megamonsoon”. (4) Seasonal movements of the ITCZ were located at lower latitudes from the Silurian to Carboniferous and from the Jurassic to the present, while reaching higher latitudes with large seasonal oscillations during the Permian-Triassic. Depending on the timing of events, these major changes in water circulation coincided with the assembly of Pangaea, the Variscan or Hercynian orogeny, the end of the late Paleozoic ice age, major carbon emissions, and global warming. These factors are closely related to the changes in atmospheric and water circulation during the Paleozoic-Mesozoic transition. The assembly of Pangea redistributed water storage and altered atmospheric circulation and the “megamonsoon”, while the elevation reduction of mountains traversing middle Pangea weakened the resistance of north and south winds. These factors promoted the evolution of a “megamonsoon” with strong seasonal swings of the ITCZ, which led to the expansion of arid zones and reduced precipitation during the Middle and Late Permian. Meanwhile, large carbon emissions and dramatic global warming altered the energy transition within global systems, which influenced atmospheric circulation. In addition, transformations of global plant clades affected the carbon budget and altered water circulation. In summary, strong fluctuations in water circulation were present during the Paleozoic-Mesozoic transition, especially as observed through climate zones, precipitation and runoff, the “monsoon”, and ITCZ. These crucial processes reflect the interaction between the lithosphere, atmosphere, hydrosphere, and biosphere. However, we have limited knowledge of the complete process of water circulation because geological records and climate simulations are extremely imprecise for the Paleozoic-Mesozoic transition. Future research could focus on other water circulation processes, such as the evolution of underground water, reserves, and fluxes of lakes, rather than only precipitation and “monsoons”. Moreover, the upgrade and extension of big data platforms and a larger number of climate simulations should be considered in future studies.

Chemical weathering indices on marine detrital sediments from a low-latitude Capitanian to Wuchiapingian carbonate-dominated succession and their paleoclimate significance

The Late Paleozoic Ice Age (LPIA) represents the most recent ice-house state on Earth, attracting significant interest from those studying recent climate change and contemporary global warming. But the duration and evolutionary pattern of LPIA are still controversial, especially when it comes to the Middle-Late Permian. A series of weathering indices on detrital sediment built from a carbonate-dominated succession in central China provides an opportunity to reveal the Capitanian to Wuchiapingian climatic fluctuations in the low latitudes and their far-field responses to the Permian glacial evolution. The weathering indices exhibit consistent trends and divide the Capitanian to Wuchiapingian interval into four phases. The first and third phases are characterized by relatively lower values in weathering indices of logarithmic parameters, CIAcor, CIXcor, CIW, αAlNa, and relatively higher values of τNa and WIPcor, which suggest a relatively cold climate occurring in the early Capitanian and late Capitanian to early Wuchiapingian. These two cold phases were relevant to the Permian glacial epochs of P3 and P4. While the second and fourth phases show opposite features in those weathering indices, which indicate the middle Capitanian and late Wuchiapingian were under a relatively warm climate. The third phase was superimposed by several cooling-warming cycles, which keep consistent in tune with sea-level fluctuations. Both of them have an average duration of about 1.0 Ma, possibly suggesting an astronomical (obliquity)-forced glacioeustatic controlling mechanism for the unstable P4 epoch. The end of co-variation of climate and sea-level fluctuation and the increase of weathering indices happened in the middle Wuchiapingian, which suggests the demise of Permian glaciation. Additionally, the latest Capitanian warming period that happened during the P4 glaciation interval corresponds to the increasing strength of the eruption of the Emeishan Large Igneous Province (ELIP), which possibly indicates the interruption of P4 was mainly controlled by the active ELIP. The limited diversity loss at the end-Guadalupian was suggested as a result of climate warming to a restricted degree, due to a limited rate and magnitude of ELIP volcanism that happened in a cold period.

The Evolution of Permian Source-to-Sink Systems and Tectonics Implications in the NW Junggar Basin, China: Evidence from Detrital Zircon Geochronology

The basin type of the Junggar Basin changed during the Permian, but the time constraint of the tectonic evolution remains unclear. Besides, the fan deltas developed in the Permian in the Mahu Sag in the northwestern of the oil-rich basin. However, the provenances of the sedimentary systems remain unclear. Based on petrology and detrital zircon U-Pb ages, this study investigates the source-to-sink systems evolution and tectonics implications. Abundant lithic clasts in sandstones with low compositional and textural maturity imply proximal sources. The dating results showed a dominant peak (310–330 Ma) and a secondary peak (400–440 Ma) in the northern Mahu Sag, only one peak at 295–325 Ma in the central Mahu Sag, several peaks at 270–350 Ma in the southern Mahu Sag, and multiple peaks at 370–450 Ma in the Zhongguai Uplift. Thus, the north-western Junggar Basin was divided into four major source-to-sink systems, with adjacent central West Junggar as the main provenance and northern and southern West Junggar as the secondary provenance. The proportion of sediment supply from the southern and northern West Junggar is higher during the Middle-Late Permian. It suggests that the source-to-sink systems show inheritance and evolve from a single provenance into a complex provenance, indicating the uplift of West Junggar. The tectonic inversion may occur early in the Middle Permian and the response to tectonic activity is stronger in the southern West Junggar than in the northern West Junggar.

Sedimentary characteristics and main controlling factors of the Middle-Upper Permian and Middle-Upper Triassic around Bogda Mountain of Xinjiang, NW China

Based on field geological survey, interpretation of seismic data and analysis of drilling and logging data, the evolution of geological structures, stratigraphic sedimentary filling sequence and sedimentary system around the Bogda Mountain were analyzed according to the idea of “structure controlling basin, basin controlling facies and facies controlling assemblages”. The tectonic evolution of the basin around the Bogda Mountain can be divided into nine stages. The Middle-Late Permian–Middle-Late Triassic was the development stage of intracontinental rift, foreland basin and inland depression basin when lake, fan delta and braided river delta sedimentary facies developed. Early intracontinental rifting, late Permian tectonic uplift, and middle-late Triassic tectonic subsidence controlled the shape, type, subsidence rate and sedimentary system evolution of the basin. The Bogda Mountain area was the subsidence center and deposition center of the deep water lake basin in the Middle Permian with mainly deep-water deposition and local gravity flow deposition. This area had tectonic inversion in the Late Permian, when the Bogda Mountain uplifted to form a low bulge and a series of fan delta sand bodies. In the Middle-Late Triassic, subsidence occurred in the Bogda low uplift, characterized by extensive development of braided river delta deposits.

Age, petrogenesis, and tectonic setting of granitic gneiss and amphibolite from the Weizigou gold deposit, Heilongjiang Province, NE China: Constraints from geochronology and geochemistry

The Weizigou gold deposit is located in the western Jiamusi Massif, Northeast China. Gold mineralization is hosted in the amphibolite, which intruded the granitic gneiss. Although the deposit shows similarities to iron-oxide–copper–gold deposits, the detailed ore-forming process remains uncertain. To determine the formation age, petrogenesis, and tectonic setting of the granitic gneiss and amphibolite, LA–ICP–MS zircon, titanite, and monazite UPb dating, whole-rock major- and trace-element analyses, and LA–ICP–MS in situ zircon Hf isotope analyses were conducted on samples from these rocks. The granitic gneiss yielded two age populations of 951–882 Ma, and ca. 500 Ma, with a monazite UPb concordia age of 501.5 ± 5.1 Ma. The amphibolite yielded a crystallization age of 292 Ma, consistent with the results for magmatic titanite UPb dating, and a metamorphic age of 272–258 Ma. The granitic gneiss contains typical aluminum-rich minerals, such as garnet and muscovite, mean SiO2 = 73.31 wt%, and molar ratio Al2O3/(CaO + K2O + Na2O) values of 1.02–1.07, indicating an S-type granite protolith. The amphibolite belongs to the tholeiitic basalt series and has low SiO2 and high MnO contents. These results, together with εHf(t) values and two-stage model ages ranging from −9.5 to 2.3 and − 0.3 to 5.7, and from 2010 to 1659 Ma and from 1331 to 947 Ma, respectively, allow us to infer that the parental magmas of the granitic gneiss and amphibolite were derived from the partial melting of Paleoproterozoic lower crust and the partial melting of metasomatized depleted mantle, respectively. The granitic gneiss is characterized by positive Th and Hf anomalies, and negative Nb, Ta, Sr and Ti anomalies, whereas the amphibolite is enriched in K, Rb, and depleted in Ba, Nb, Ti, and Zr. These geochemical features suggest that the S-type granite was formed in an active continental margin during the Neoproterozoic and underwent granulite-facies metamorphism during the early Paleozoic. The protolith of the amphibolite was gabbro that formed in an extensional setting (e.g., a backarc basin) associated with westward subduction of the Paleo-Pacific oceanic plate beneath the eastern Jiamusi Massif during the early Permian. The gold mineralization can most likely be attributed to contact metasomatic metamorphism of gabbro during the middle–late Permian.

Stratigraphic-Tectonic Evolution and Characterization of the Carboniferous in the Karamay–Baikouquan Fault Zone in the Northwestern Margin of the Junggar Basin, Northwest China

The northwestern margin of the Junggar Basin has a complex tectonic history, which is challenging for hydrocarbon exploration. This study highlights the structural patterns, tectonic evolution, and controlling factors of the Karamay–Baikouquan Fault Zone (KBFZ) in the northwestern margin of the Junggar Basin based on well-log and 3D seismic data. The main findings of this study include the following: spatially, we have divided the structural patterns of KBFZ into three zones on the plane, namely, northern, central, and southern zones; temporarily, the tectonic evolution has been divided into five stages from Late Carboniferous to Cretaceous, namely, Early-Middle Carboniferous, Late Carboniferous-Early Permian, Middle-Late Permian, Triassic-Middle Jurassic, and Late Jurassic-Cretaceous. During the Hercynian and Indochina orogeny, the compressional stress from the movement of the Dalabute strike-slip fault and the Genghis–Junggar strike-slip fault produced various degrees of deformation in different locations in the KBFZ. The general structural style is a mixture of strike-slip and thrust-nappe. The main controlling factors include stress period, stress direction, and stratigraphic-lithologic associations. This study has implications for hydrocarbon exploration and development in the northwestern margin of the Junggar Basin.

Disturbance of Organizational Equilibrium during the Change of Ancient Tetrapod Communities: Its Manifestations at the Middle–Late Permian Transition

Disturbance of Organizational Equilibrium during the Change of Ancient Tetrapod Communities: Its Manifestations at the Middle–Late Permian Transition