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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.

The Longmenshan region is the geographical boundary between the Sichuan Basin and the eastern Tibetan Plateau, but whether it is the tectonic boundary between the Yangtze Block and Songpan-Garze terrane is still controversial. Meanwhile, the Early Devonian floral differentiation between the Longmenshan region and the southern part of the Yangtze Block, such as Yunnan and Guizhou provinces, also leads to controversy. Here we report U-Pb ages of detrital zircons from Lower Devonian sandstones of the Longmenshan region, providing evidence to discuss the tectonic affinity of the Longmenshan region and possible reasons for the Early Devonian floral differentiation. Detrital zircon U-Pb age patterns show that the Pingyipu Group defines three principal age populations of 2.6–2.4 Ga, 1.2–0.7 Ga, and 0.7–0.5 Ga, with two minor distributions of 1.8–1.5 Ga and 480–420 Ma. This U-Pb age spectrum is consistent with that of the Lower Devonian Danlin Formation of Guizhou, indicating that the Pingyipu Group and the Danlin Formation might share the same or similar sources. Together with fossil evidence, it is suggested that the Devonian sedimentary successions in the Longmenshan region are deposited in the western margin of the Yangtze Block, indicating the western boundary of this block is likely in somewhere to the west of Longmenshan fault, such as the Longriba fault. The Neoproterozoic strata located between the Longmenshan region and Yunnan–Guizhou provinces contain dominant Paleoproterozoic detrital zircons (2.1–1.9 Ga), however, this population is almost absent in the Pingyipu Group and the Danlin Formation, suggesting that there might not exist a denudation area (about 3000 masl) to supply sediments for Lower Devonian strata and separate the Longmenshan region and Guizhou. Therefore, the Early Devonian floral differentiation between the Longmenshan region and Yunnan–Guizhou provinces might not be caused by tectonic or mountainous barriers as previously suggested, but instead, might be caused by different depositional ages of the strata at a finer temporal resolution and environmental factors, such as different climatic conditions and/or habitat heterogeneity.

Many new specimens (36 in total) of gastropods were collected from the Ordovician Alai Formation of the Chiatsun Group at Jiacun village, Nyalam County, southern Xizang (Tibet). These gastropods comprise five species assigned to two genera, including Maclurites parviumbilicatus Yu, M. cf. nyalamensis Yu, M. cf. xizangensis Yu, M. cf. subconicus Yu, and “Hormotoma” ordosensis Yu, forming a Maclurites-“Hormotoma” association. All the species are described in detail herein, and some of which are redefined. This fauna is of middle to late Darriwilian age, and palaeoecologically characterised by species of shallow-water within the photic zone. A comparison of the Maclurites community with the contemporary gastropod fauna from the Zhuozishan Formation exposed along the west margin of the North China Block shows a close palaeogeographical affinity. The occurrences of Ordovician gastropods from China are analyzed biogeographically and the results reveal that the peri-Gondwana gastropod faunal turnover event was initiated during the Middle to Late Ordovician transition. The coincident faunal turnover and the lithofacies changes in the Himalaya and western margin of North China suggest that tectonic activities and relative sea-level changes may account for the biogeographical affinities of some specific fossil groups in peri-Gondwanan regions.

The Pennsylvanian rugose corals are not well understood in Northwest China due to their low diversity and restricted distribution under the impact from coeval Gondwana glaciation. In this study, nine rugose coral species of eight genera are described from the Shiqiantan and Jingou formations (Moscovian to Kasimovian stages) in the new Shuangjingzi Section, northern Xinjiang, Northwest China. These species include dissepimented solitary rugose corals (Arctophyllum shuangjingziense n. sp., Arctophyllum intermedium, Caninophyllum ürümqiense, Gshelia qitaiensis, Pseudotimania aff. junggarensis, Pseudozaphrentoides paramapingensis), and non-dissepimented solitary corals (Amplexizaphrentis sp., Bradyphyllum bellicostatum and Hapsiphyllum sp.). This coral assemblage includes local taxa of the Junggar Basin, with a few common elements from Urals Mountains, Novaya Zemlya, and Spitsbergen in northwestern Palaeotethys Ocean. The composition of the Shuangjingzi corals is characterized by the medium-large dissepimentarium Caninophyllum ürümqiense-Gshelia qitaiensis assemblage, indicating open shallow carbonate environments. Compared with the Shiqiantan Formation, the obvious increase in the abundance of narrow-dissepimentarium corals of Gshelia in the upper Jingou Formation, implies that low-energy environments could have developed, with an increase of shales in this interval.

We report isolated postcranial materials newly excavated from the Middle Jurassic Dongdaqiao Formation in Chaya County, Qamdo City, eastern Tibet. The specimens are assignable to Eusauropoda based on the following combination of characters: huge size of caudal vertebrae and humeral shaft, weakly developed amphicoelous caudal centrum, femoral distal ends with two condyles and a shallow intercondylar groove, and rod-like transverse process of the anterior caudal vertebra with its base not extending to the neural arch. Due to the fragmentary nature of the specimens, we refrain from assigning them to lower taxonomic levels or new species of sauropod until more complete materials are excavated from Qamdo. Nevertheless, the new materials from Qamdo demonstrate that some gigantic sauropods migrated to eastern Tibet during the Middle Jurassic and were more widely distributed than previously known.