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The Early Devonian witnessed dramatic changes in climate, ocean chemistry and faunal evolution. However, previous studies have relied mainly on records from North America and Europe (Prague Basin, Carnic Alps) and Australia, while data from China have been rarely reported, hindering robust δ¹³C_carb chemostratigraphic correlation and evidence for the global significance of these events. Here, we report new carbon isotope and conodont apatite oxygen isotope records from the Alengchu section in western Yunnan which represents the most continuous Lower Devonian carbonate succession in China. Our study reports two positive δ¹³C_carb excursions (Klonk isotope event, Lochkovian–Pragian isotope event) that can be correlated with published records globally. However, δ¹⁸O_apatite values are higher compared to coeval data from other sections. These higher values are interpreted as indicating cooler surface water temperatures as consequence of a persistent upwelling system at low latitudes which is consistent with the paleooceanographic circulation pattern reconstructed from combined evidence of climate modelling and geographic distribution of marine benthic ostracod assemblages.

Based on the conodonts recovered for the first time and some brachiopods, this study revises the age of the Wuqingna Formation in eastern Tibet to a late Famennian, challenging prior Carboniferous classification based on coral assemblages. In this study, conodonts are described for the first time from the Wuqingna Formation on the Wuqingka Mountain near Toba Town, Qamdo City in eastern Tibet. The conodont assemblage contains 6 species/subspecies (including morphotypes within open nomenclature) that belong to three genera. The conodont species Polygnathus cf. perplexus, Po. homoirregularis, Po. wuqingnaensis n. sp. and Scaphignathus peterseni suggest an age of late Famennian, probably the Palmatolepis gracilis manca Zone to the Pa. gr. expansa Zone, for the lower part of the Wuqingna Formation, which was previously assigned to the Carboniferous based on the rugose coral assemblages.

Eleven Ordovician conodont species of nine genera from the Ban Tha Kradan area of western Thailand are described and illustrated here for the first time. Based on similar lithological features and stratigraphical range, the upper part of Tha Manao Formation in the Ban Tha Kradan area of Kanchanaburi Province is amended and assigned to the Pa Kae Formation. The Scolopodus striatus Assemblage Zone is recognized in the revised Tha Manao Formation in the Ban Tha Kradan area. Based on conodonts and macrofossils, the Tha Manao Formation in western Thailand is assigned to the upper Floian to Darriwilian, and the conformably overlying Pa Kae Formation to the Sandbian to lower Katian.

We carried out, for the first time, detailed studies on the coral-stromatoporoid patch reefs from the Lazhuglung Formation near Shouxinghu in the Lazhuglung-Badangco area, Ngari Prefecture of Xizang (Tibet) Autonomous Region, China. On the basis of 1085 thin sections prepared from three patch reefs, the fossil components and reef structures are depicted. The patch reefs are found to encompass diverse fossil organisms, including tabulate and rugose corals, stromatoporoids, brachiopods, gastropods, ostracods, nautiloids, calcified cyanobacteria, and tubeworms. Tabulate corals and stromatoporoids are the predominant reef-builder, particularly Alveolites obtortus and Gerronostromaria gromotuchense. The patch reefs are Middle Devonian Givetian in age based on the tabulate coral and stromatoporoid assemblage. Extensive biotic interactions between the reef organisms are found in all three patch reefs, which are beneficial for the reef formation and development. The ecological features of the corals and stromatoporoids indicate a mesophotic ecosystem that is widespread in the Givetian. In addition, the common species and similar characteristics between the faunas in the Lazhuglung Formation, North Qiangtang Block and those in South China suggest a close palaeobiogeographic relationship. This study enhances our understanding on fossil components, reef structure and tectonic affiliation of the Palaeozoic strata in the Lazhuglung-Badangcuo area.

The Baoshan Block was part of the eastern Cimmerian continent along the northeastern margin of Gondwana during the late Paleozoic, and preserves continuous sedimentary records during the apex of the Early Permian glaciation. Although much work has been carried out on biostratigraphy and paleogeography, detailed sedimentological study of the glacial records in the Baoshan Block has gained little attention, which hampers the understanding of depositional processes along the northeastern margin of Gondwana. Here, we conduct a high-resolution sedimentological study on the Lower Permian Dingjiazhai Formation of the Baoshan Block, with the aim of reconstructing the evolution of sedimentary environments. Six major lithological facies and three facies associations are recognized from the Dongshanpo section. The diamictite facies association is composed of weakly stratified diamictite, stratified diamictite, and massive sandy siltstone facies, which are formed by proglacial outwash debris flows and settling of melt-water plumes. The lenticular gravelly sandstone facies association consists of lenticular gravelly sandstone, thin-bedded siltstone, and homogenous silty mudstone facies, suggesting a distal subaqueous proglacial offshore setting with episodic melt water plumes. The bioclastic rudstone facies association comprises of bioclastic rudstone and floatstone, and thin-bedded siltstone facies, which suggest an offshore depositional environment punctuated by bioclastic gravity flows. Accordingly, we reconstructed a gradually changed sedimentary model responding to the Early Permian deglaciation in the Baoshan Block, which probably represents a typical evolution of sedimentary environments along the northeastern margin of Gondwana during the Early Permian.

The opening time of the Bangong-Nujiang Ocean (BNO, also known as the Meso-Tethys Ocean) remains controversial. It was documented to have opened during the Permian, Early Palaeozoic or Mesozoic times. The Permian faunas and their palaeobiogeographical affinities of the Lhasa and South Qiangtang blocks bordered by the Bangong-Nujiang Suture Zone are crucial for reconstructing the tectonic evolution of both blocks and determining the opening time of the BNO. This paper describes two new lower Cisuralian brachiopod faunas from the uppermost Yunzhug Formation of the Lhasa Block and the Zhanjin Formation of the South Qiangtang Block. These two faunas exhibit a high similarity in composition, both containing species of Bandoproductus, Spirelytha and Sulciplica thailandica. Comparable brachiopod faunas are found from the glaciomarine diamictites in the blocks of the eastern Cimmerian belt including the Baoshan, Irrawaddy and Sibuma, as well as the Tethys Himalaya and the Gondwanaland. They are herein named the Bandoproductus-Spirelytha association, which exhibits apparent Gondwanan affinities. Cluster analysis and principal components analysis are employed to conduct a palaeobiogeographical reconstruction of the Asselian–Sakmarian brachiopod faunas primarily from the aforementioned tectonic units. A single palaeobiogeographical unit, the Indoralian Province, is recognised and represented by the unified brachiopod association. This suggests that most of the Cimmerian blocks, including the Lhasa and South Qiangtang blocks, were attached to the northern Gondwanan margin during the early Cisuralian. This is in contrast to our previous results revealed by multiple quantitative analyses for the Kungurian–Roadian brachiopod faunas in the Tethys, which show distinct faunal differences between the Lhasa and South Qiangtang blocks. This palaeobiogeographical discrepancy suggests that the two blocks probably had varying northward drifting tempos after they detached from the Gondwanaland, that is, the South Qiangtang Block drifted faster and incorporated into the temperate-warm region of the Northern Cimmerian Subprovince; whereas the Lhasa Block drifted relatively slowly and retained to be close to the northern Gondwanan margin and belonged to the Southern Cimmerian Subprovince during the late Cisuralian. The faunal differences provided critical implications that the BNO probably had opened in the Artinskian and reached a certain width with distinct faunal differences during the Kungurian.

The Earth’s climate has been proved to be consistently paced by the quasi-periodic sunspot activity since the Paleoproterozoic. However, climatic response to the sunspot cycles in high-altitude areas under greenhouse condition is still unclear, largely due to the lack of high-resolution palaeoclimatic data. Here we present a continuous, 30-cm-long core sample from the Eocene upper Xiaganchaigou Formation in the southwestern Qaidam Basin in the northern Tibetan Plateau. This core is marked by well-preserved annually chemogenic varves, composed of couplets of light micrite and dark clastic laminae. Varve thickness mainly ranges from 0.1 to 0.5 mm. Power spectrum of the bed number series of varve thickness shows a distinct cycle with a period of ∼20 year, which can be related to the 22-year Hale sunspot cycle. In addition, we use XRF (X-ray fluorescence) Ca concentration and K/Ti ratio data and μ-XRF (micro-X-ray fluorescence) Ca and K intensity data as paleoclimate proxies to conduct detailed cyclostratigraphic analyses. Power spectra of these proxies show sedimentary cycles at wavelengths of ∼40–12 mm, ∼8–3 mm, 3–1 mm and 0.2–0.1 mm, which are most likely caused by the ∼90-year Gleissberg sunspot cycle, 22-year Hale sunspot cycle, 11-year Schwabe sunspot cycle and annually seasonal cycle, respectively. The consistent results from the above five independent paleoclimate proxies indicate that climate in the high-altitude Qaidam Basin in the Eocene greenhouse period was paced by multiple-scale sunspot cycles. Periodic variances in total solar irradiance (TSI) and galactic cosmic ray (GCR)-related clouds paced by sunspot cycles may play a key role on modulating regional climatic changes in the Qaidam Basin.

To identify its type and evolution features of the Middle Jurassic–Early Cretaceous basin at the northern margin of the Lhasa Block (NMLB) is of great significance for reconstructing its tectonic-paleogeography and assessing the petroliferous basins in the Bangong-Nujiang suture zone (BNSZ) and its adjacent area. This study conducted the sedimentary characteristic analyses and detrital zircon U-Pb dating of the Middle Jurassic–Lower Cretaceous strata exposed in the northern part of Nagqu County (NPNC), Tibet. The Middle–Upper Jurassic Lagongtang Formation was mainly deposited in a steep slope delta and its middle part is characterized by debris flows moving southeastward. The lower part of the Upper Jurassic–Lower Cretaceous Duoni Formation was characterized by molasses formation, and its middle and upper part were primarily deposited on a tidal flat-mixed shelf. The 384 detrital zircons from the debris-flow deposits of the Lagongtang Formation yielded ages of 2800∼210 Ma, except for one yielding an age of 174 Ma. The detrital zircons from the lower part of the Duoni Formation yielded ages of 2744∼152 Ma. Comprehensive research results show that the basin located at the NMLB is a peripheral foreland basin controlled by the BNSZ and had dual source supply, and around 152 Ma, the basin was accompanied by a stronger overthrust event and experienced the conversion from flysch basin to molasses one. Subsequently, a new foreland basin formed marked by the deposition of the Shamuluo Formation in the BNSZ.

The South Qiangtang Block (SQB) was widely acknowledged as a part of the Cimmerian Continent, which rifted away from Gondwanan margin during the Early Permian. However, the sedimentary response to this rifting event has thus far not been unequivocally confirmed, which makes this event ambiguous. In this contribution, three stratigraphic successions are recognised, which are characterised by distinct facies and record different stages in the tectonic evolution of the basin and associated changes in the rates of basin subsidence and sediment accommodation. Succession 1 comprises glacio-marine deposits which are dominated by dark shales and diamictites (Cameng and Zhanjin formations) originated mainly from both gravity flow and downslope resedimentation. Succession 2 is predominated by shallow-water sandstones of delta setting (lower Qudi Formation). Succession 3 is composed of deposits of tidal flat and platform (upper Qudi and Tunlonggongba formations). The sedimentary facies changes fit well with marine rift-basin successions: (1) Succession 1 clearly records ‘sediment underfilled’ stage characterised by rapid tectonic subsidence, low sediment supply, and marks an early to climax stage of syn-rift; (2) deltaic sandstones facies of Succession 2 records ‘sediment filled and overfilled’ when sediment supply consumes up the accommodation, and marks a late stage of syn-rift during the tectonic quiescence period; (3) tidal-rhythmites of Succession 3 is likely a record of short-term autogenic cycles, indicating a possible post-rift stage. Therefore, these successions within the western SQB during the Early Permian was best explained by the tectonic subsidence resulted from the rifting of the SQB from the Gondwanan margin.

We report conodont assemblages from the Dardong Formation of the Xainza area, Lhasa Block, yielding several chronostratigraphically significant conodont elements discovered from the Lhasa Block for the first time, including Gondwania profunda, Polygnathus pannonicus, P. kitabicus, P. cf. sokolovi and P. excavatus excavatus. Two conodont zones are identified, namely, the middle Pragian profunda Zone and the lower Emsian excavatus Zone. The Pragian–Emsian boundary is presumably located within the interval between bioclastic limestone beds 4 and 6 with an interbed of siltstones. Although the sparse conodont occurrences in this study precludes more precise chronostratigraphic subdivision, the Xainza area of the Lhasa Block is potentially important for recognition of Lower Devonian stage boundaries in China and deserves further conodont investigations.