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Background: Annual health examination is recommended for the prevention and treatment of cardiovascular diseases and diabetes. However, whether it is effective for the prevention of hyperlipidemia and hyperglycemia remains unclear. Methods: A retrospective analysis of clinical samples using the laboratory information system was performed. From 2012 to 2019, 5043 participants (1755 males and 3288 females) have completed the annual health examination for 8 consecutive years, which was the follow-up group. In the same period, 136,994 participants (the control group) had a health examination only 1 time. Serum levels of fasting triglyceride (TG), total cholesterol (TC), low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C) and glucose (GLU) were measured.Results: Compared with 2019 of the control group, serum TC and GLU in the 8th year of the follow-up group increased markedly in some of age groups (p < 0.001). Serum TG and TC in the 8th year were much higher compared with the 1st year of the follow-up group, especially for the female (p < 0.001). Moreover, the prevalence of hyperlipidemia and hyperglycemia in the 8th year showed significant increase compared with the 1st year of the follow-up group and 2019 of the control group (all p < 0.05).Conclusions: Annual health examination didn’t perform a positive effect in the prevention of hyperlipidemia and hyperglycemia. Health management should be paid more attention to prevent cardiovascular disease and diabetes.

Using Chinese data from 2004 to 2016, we investigate the effects of business models on bank risk before, during and after financial crisis. Three main results emerge. First, insolvency risk and ROA...

Using data from China’s banks between 1995 and 2017, we employ propensity score matching and difference in differences approaches to investigate the effects of going public on bank risks, including...

Significance Synaptic plasticity in the hippocampus is important for learning and memory formation. In particular, homeostatic synaptic plasticity enables neurons to restore their activity levels in response to chronic neuronal activity changes. While astrocytes modulate synaptic functions via the secretion of factors, the underlying molecular mechanisms remain unclear. Here, we show that suppression of hippocampal neuronal activity increases cytokine IL-33 release from astrocytes in the CA1 region. Activation of IL-33 and its neuronal ST2 receptor complex promotes functional excitatory synapse formation. Moreover, IL-33/ST2 signaling is important for the neuronal activity blockade-induced increase of CA1 excitatory synapses in vivo and spatial memory formation. This study suggests that astrocyte-secreted IL-33 acts as a negative feedback control signal to regulate hippocampal homeostatic synaptic plasticity., Hippocampal synaptic plasticity is important for learning and memory formation. Homeostatic synaptic plasticity is a specific form of synaptic plasticity that is induced upon prolonged changes in neuronal activity to maintain network homeostasis. While astrocytes are important regulators of synaptic transmission and plasticity, it is largely unclear how they interact with neurons to regulate synaptic plasticity at the circuit level. Here, we show that neuronal activity blockade selectively increases the expression and secretion of IL-33 (interleukin-33) by astrocytes in the hippocampal cornu ammonis 1 (CA1) subregion. This IL-33 stimulates an increase in excitatory synapses and neurotransmission through the activation of neuronal IL-33 receptor complex and synaptic recruitment of the scaffold protein PSD-95. We found that acute administration of tetrodotoxin in hippocampal slices or inhibition of hippocampal CA1 excitatory neurons by optogenetic manipulation increases IL-33 expression in CA1 astrocytes. Furthermore, IL-33 administration in vivo promotes the formation of functional excitatory synapses in hippocampal CA1 neurons, whereas conditional knockout of IL-33 in CA1 astrocytes decreases the number of excitatory synapses therein. Importantly, blockade of IL-33 and its receptor signaling in vivo by intracerebroventricular administration of its decoy receptor inhibits homeostatic synaptic plasticity in CA1 pyramidal neurons and impairs spatial memory formation in mice. These results collectively reveal an important role of astrocytic IL-33 in mediating the negative-feedback signaling mechanism in homeostatic synaptic plasticity, providing insights into how astrocytes maintain hippocampal network homeostasis.

Prolonged exposure to negative stressors could be harmful if a subject cannot respond appropriately. Strategies evolved to respond to stress, including repetitive displacement behaviours, are important in maintaining behavioural homoeostasis. In rodents, self-grooming is a frequently observed repetitive behaviour believed to contribute to post-stress de-arousal with adaptive value. Here we identified a rat limbic di-synaptic circuit that regulates stress-induced self-grooming with positive affective valence. This circuit links hippocampal ventral subiculum to ventral lateral septum (LSv) and then lateral hypothalamus tuberal nucleus. Optogenetic activation of this circuit triggers delayed but robust excessive grooming with patterns closely resembling those evoked by emotional stress. Consistently, the neural activity of LSv reaches a peak before emotional stress-induced grooming while inhibition of this circuit significantly suppresses grooming triggered by emotional stress. Our results uncover a previously unknown limbic circuitry involved in regulating stress-induced self-grooming and pinpoint a critical role of LSv in this ethologically important behaviour., Self-grooming is a frequently observed repetitive behaviour in rodents that is believed to contribute to post-stress de-arousal. The authors identified a previously unknown limbic circuit that includes the ventral lateral septum in rats and is involved in regulating stress-induced self-grooming.

Multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) enables the precise determination of mercury (Hg) isotopic compositions in different types of samples. However, isotopic measurements in samples with low Hg concentrations and small sample mass remain a challenge. In this study, we developed an optimized protocol for high precision Hg isotope determination using a modified cone arrangement (X skimmer cone + jet cone) with Neptune Plus MC-ICP-MS. Through modification of the HGX-200 continuous-flow cold-vapor generation system, and careful optimization of the instrument gas flow rates, we obtained steady and high signal sensitivity for Hg (202Hg: 1.78 V per ng mL−1). Our method allowed the precise determination of low Hg concentration in solutions (0.10 ng mL−1), which is the lowest according to the literature. Only 0.70 ng Hg in samples was required according to our new analytical method, which enables the direct measurement of low Hg concentration in samples (down to 5 ng g−1), after direct acid digestion treatment. Using our method, the Hg isotopic compositions of four igneous rock standard reference materials (BCR-2, BHVO-2, GSP-2, and GSR-2) were reported for the first time. The standard reference materials showed large variations of δ202Hg (−1.24 to −2.47‰), indicating that mass dependent fractionation (MDF) of Hg isotopes occurred during magmatic processes.

Using data hand collected in China between 2001 and 2016, this paper examines how political uncertainty affects city bank lending. Our results show that political uncertainty causes banks to significantly increase loan growth. These results are moderated by the characteristics of government officials, bank characteristics, and the degree of marketization. Our results further show that changes by government officials increase medium-term loan growth, mainly for the real estate and public utilities sector. Finally, we show that city government official changes increase bank lending and, thus, increase credit risk, that is, bank lending has a mediating effect.

Using hand-collected data in China from 2001 to 2019, we examine how political uncertainty affects corporate political activities, including corporate corruption and corporate charitable donations, and whether the anti-corruption campaign moderates the relationship between political uncertainty and corporate political activities. First, we find that when city government officials change, local firms significantly increase corporate charitable donations while reducing corporate corruption. Second, the anti-corruption campaign strengthens the effects of political uncertainty on corporate political activities. Third, our results also show that political uncertainty has stronger effects 1) when new government officials come from external appointments, and 2) when former government officials experience abnormal turnover. In addition, the effects of political uncertainty on corporate charitable donations are stronger in non-state-owned enterprises and firms belonging to regulated industries. Finally, political uncertainty increases firms’ government subsidies through corporate political activities. It’s clear that political activities have mediating effects.

Using China’s data between 1995 and 2014, we employ the propensity score matching and difference in differences approaches to investigate the effects of foreign strategic investors (FSIs) on bank prudential behavior, and find the following results. First, lending behavior and reserve behavior become prudential after introducing FSIs. Second, FSIs assigning directors or managers could improve the bank’s prudence. Third, the effects of FSIs on bank prudence are weaker in state-owned banks than in non-state-owned banks. Finally, further analyses show that FSIs may reduce bank risk through improving prudential behavior, that is, prudential behavior is a mediator between FSIs and bank risk.

Introducing foreign strategic investors (FSIs) has been vital to China's bank ownership reforms. Using relevant data between 1995 and 2014, we employ the propensity score matching and difference in differences approaches to investigate the effects of FSIs on bank risks, including insolvency risk, capital risk, liquidity risk, asset quality, and credit risk. We make several findings. First, FSIs may significantly reduce bank risks, with the exception of insolvency risk. Second, the effects of FSIs on capital risk, liquidity risk, asset quality, and credit risk are weaker in state-owned banks than in non-state-owned banks. In addition, FSIs-assigned directors and managers could further decrease bank capital risk, liquidity risk, and credit risk, and improve bank asset quality. And directors and managers have weaker effects on bank risks in state-owned banks. Finally, bank risks exhibit no significant changes after FSI exits, and the effects of FSIs on bank risks do not differ between banks without and with exited FSIs. This suggests that spillover effects work more than monitoring effects in the context of China's financial background.

New geological, geochronological and isotopic data reveal a previously unknown arc system that evolved south of the Kyrgyz Middle Tianshan (MTS) microcontinent during the Middle and Late Ordovician, 467-444 Ma ago. The two fragments of this magmatic arc are located within the Bozbutau Mountains and the northern Atbashi Range, and a marginal part of the arc, with mixed volcanic and sedimentary rocks, extends north to the Semizsai metamorphic unit of the southern Chatkal Range. A continental basement of the arc, indicated by predominantly felsic volcanic rocks in Bozbutau and Atbashi, is supported by whole-rock Nd- and Hf-in-zircon isotopic data. epsilon(Nd(t)) of + 0.9 to -2.6 and epsilon(Hf(t)) of +1.8 to -6.0 imply melting of Neo- to Mesoproterozoic continental sources with Nd model ages of ca. 0.9 to 1.2 Ga and Hf crustal model ages of ca. 1.2 to 1.7 Ga. In the north, the arc was separated from the MTS microcontinent by an oceanic back-arc basin, represented by the Karaterek ophiolite belt. Our inference of a long-lived Early Palaeozoic arc in the southwestern MTS suggests an oceanic domain between the MTS microcontinent and the Tarim craton in the Middle Ordovician. The time of arc-continent collision is constrained as Late Ordovician at ca. 450Ma, based on cessation of sedimentation on the MTS microcontinent, the age of an angular unconformity within the Karaterek suture zone, and the age of syncollisional metamorphism and magmatism in the Kassan Metamorphic Complex of the southern Chatkal Range. High-grade amphibolite-facies metamorphism and associated crustal melting in the Kassan Metamorphic Complex restricts the main tectonic activity in the collisional belt to ca. 450 Ma. This interpretation is based on the age of a synkinematic amphibolite-facies granite, intruded into paragneiss during peak metamorphism. A second episode of greenschist- to kyanite-staurolite-facies metamorphism is dated between 450 and 420 Ma, based on the ages of granitoid rocks, subsequently affected or not affected by this metamorphism. The latest episode is recorded by greenschist-facies metamorphism in Silurian sandstones and granodiorites and by retrogression of the older, higher-grade rocks. This may have occurred at the Silurian to Devonian transition and reflects reorganization of a Middle Palaeozoic convergent margin. Late Ordovician collision was followed by initiation of a new continental arc in the southern MTS. This arc was active in the Early Silurian, latest Silurian to Middle Devonian, and Late Carboniferous, whereas during the Givetian through Mississippian (ca. 385-325 Ma) this area was a passive continental margin. These arcs, previously well constrained west of the Talas-Ferghana Fault, continued eastwards into the Naryn and Atbashi areas and probably extended into the Chinese Central Tianshan. The disappearance of a major crustal block with transitional facies on the continental margin and too short a distance between the arc and accretionary complex suggest that plate convergence in the Atbashi sector of the MTS was accompanied by subduction erosion in the Devonian or Early Pennsylvanian. This led to a minimum of 50-70 km of crustal loss and removal of the Ordovician arc as well as the Silurian and Devonian forearcs in the areas east of the Talas-Ferghana Fault. (C) 2016 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.

This study documents the metamorphic evolution of mafic granulites from the Eastern Hebei Complex in the Eastern Block of the North China Craton. Mafic granulites from Eastern Hebei occur as boudins or enclaves within Neoarchean high-grade TTG gneisses. Petrographic observations reveal three characteristic metamorphic mineral assemblages in the mafic granulites: the pre-peak hornblende + plagioclase + ilmenite + quartz + sphene assemblage (M1) existing as mineral inclusions within coarse-grained peak assemblage (M2) represented by garnet + clinopyroxene + orthopyroxene + plagioclase + hornblende + ilmenite + quartz, and post-peak assemblage (M3) marked by garnet + quartz ± ilmenite symplectites surrounding the peak pyroxene and plagioclase. Based on pseudosection modeling calculated in the NCFMASHTO model system using the program THERMOCALC, P–T conditions of the pre-peak (M1), peak (M2) and post-peak (M3) assemblages are constrained at 600–715 °C/6.0 kbar or below, 860–900 °C/9.6–10.3 kbar, and 790–810 °C/9.6–10.4 kbar, respectively. These P–T estimates, combined with their mineral compositions and reaction relations, define an anticlockwise P–T path incorporating isobaric cooling subsequent to the peak medium-pressure granulite-facies metamorphism for the mafic granulites from Eastern Hebei. Such an anticlockwise P–T path suggests that the end-Neoarchean metamorphism of the Eastern Hebei Complex correlated closely with underplating and intrusion of voluminous mantle-derived magmas. In conjunction with other geological considerations, a mantle-plume model is favored to interpret the Neoarchean tectonothermal evolution of the Eastern Hebei Complex and other metamorphic complexes in the Eastern Block. The prograde amphibolite-facies metamorphism (M1) was initiated due to the upwelling of the relatively cooler mantle plume head, followed by the peak medium-pressure granulite-facies metamorphism (M2) as triggered by the uprising hotter plume “tail”, and finally when plume activity ceased, the heated metamorphic crust experienced nearly isobaric cooling (M3).

Zircon age data for felsic metavolcanic rocks of the Sandspruit and Theespruit formations, the two oldest supracrustal components in the Palaeoarchaean Barberton Greenstone Belt, show that these two successions are time-equivalent and constitute one single volcanic event at ca. 3530 Ma. The Sandspruit felsic rocks are ubiquitously metasomatized, intensely deformed and intruded by, and tectonically interlayered with, ca. 3450 Ma granitoid sills that are probably part of the Theespruit Pluton. One metasomatized Sandspruit sample contains abundant metamorphic zircons with a weighted mean 207Pb/206Pb age of 3220.1 ± 1.6 Ma, reflecting a widespread metamorphic event in parts of the eastern Kaapvaal craton in South Africa and Swaziland. Several samples of felsic metavolcanic rocks of the Theespruit formation confirm a previously established magmatic emplacement age of ca. 3530 Ma, but slightly older rocks up to 3552 Ma were found in the easternmost exposure of the Theespruit sequence near the South African/Swaziland border and may represent a lower lithostratigraphic level than exposed farther west. Hf-in-zircon isotopic data for most felsic metavolcanic rocks confirm earlier results suggesting that these rocks predominantly originated from melting of a felsic continental basement, possibly related to the oldest, ca. 3660–3550 Ma components of the Ancient Gneiss Complex in Swaziland. However, several Sandspruit samples also suggest that a juvenile source was involved in their generation, perhaps a mafic underplate. We see no evidence in the geochemistry and isotopic signatures of felsic volcanic rocks of the Sandspruit and Theespruit formations for partial melting of a metabasaltic protolith and for Palaeoarchean oceanic crust that formed in connection with subduction. We rather favor a plateau-type setting on older continental crust.

The ca. 3480–3430 Ma Tsawela Gneiss (TG) is a well-preserved coarse-grained diorite to tonalite suite within the Ancient Gneiss Complex of Swaziland, eastern Kaapvaal craton. These gneisses are texturally and compositionally distinct from the hosting oldest components of the ca. 3200–3660 Ma TTG-type Ngwane Gneisses (NG). Major and trace elements, in combination with whole-rock hafnium-neodymium isotopic data, were analyzed in the TG and in three samples of ca. 3450 Ma grey NG to constrain sources and magmatic processes. High-field-strength element data (HFSE) were combined with U-Pb SHRIMP II ages and Hf-in-zircon data for key samples to constrain their ages and petrogenesis. In contrast to the widespread view that Archaean crust is mainly composed of TTG igneous suites that formed from juvenile sources, the geochemical and isotopic compositions of the TG indicate that these rocks represent a calc-alkaline plutonic suite which possibly formed by magma mixing processes involving juvenile, mantle-derived tholeiitic melts as well as partial melts of the older Ngwane gneiss. Alternatively, the TG may represent a magmatic suite that formed by fractional crystallization of a hydrous intermediate magma. These results contrast with field evidence of a relatively uniform and homogeneous composition. Our geochronological and isotopic data show that the TG intruded the NG during a time span of at least 50 Ma without any significant compositional change of the source. The predominant influence of fractional crystallization of a tholeiitic mafic magma, as well as assimilation-fractional-crystallization processes (AFC) can be excluded for the TG from major and trace element modelling. The magma processes proposed here suggest efficient mixing of approximately equal amounts of TG magmas with those derived from the NG basement and is supported by the largely homogeneous Hf-Nd isotopic compositions of the whole-rock samples. We propose that melting and mixing occurred in the lower crust that mainly consisted of >3.50 Ga NG and was possibly triggered by plume-related underplated and intraplated tholeiitic magmas in sills and/or laccoliths. This model is supported by geochemical evidence for a mafic end member lacking a negative Nb anomaly and implying that subduction processes were not involved in the formation of the TG.

Sanukitoids and their equivalents are rare subduction-related rock types that have been found in modern arc settings and in Late Archean sequences. The investigation of sanukitoids is of particular importance to a better understanding of crust-forming processes and continental growth. In this paper we report zircon U–Pb and Ar–Ar ages and major element, trace element, and Sr–Nd–Hf isotope data for the Bieluagaxi dioritic pluton and dikes from the southern part of the West Junggar, NW China. These rocks formed in the Early Permian and show a remarkable geochemical affinity with Cenozoic sanukitoids of the Setouchi Volcanic Belt of SW Japan with high Mg# (48–73) values, Cr (54–539 ppm), Ni (21–197 ppm) contents and Th/La (0.15–0.37) ratios and low Sr/Y ratios (16–27) and Sr (263–442 ppm) contents. They may be generated by the partial melting of subducting sediments, and subsequent melt–mantle interaction. Additionally, the sanukitoids are also widespread in the Karamay–Baogutu area of West Junggar accompanied by high Sr (average 713 ppm) contents and Sr/Y (50–130) ratios, and low Y (6.9–12.6 ppm) contents. The difference in petrochemical characteristics between the Baogutu–Karamay and Bieluagaxi sanukitoids can be explained by the difference in depth of initial melting, origin composition and fractional crystallization. The Baogutu–Karamay sanukitoids were probably formed under eclogitic conditions, while the Bieluagaxi sanukitoids were at a shallower depth. Moreover, the compositional similarity between continental-crust forming rocks and the Bieluagaxi sanukitoids suggests that the sanukitoids genesis could be closely related to the process of continental crust formation. The Late Carboniferous–Early Permian sanukitoids in the West Junggar may be an indicator of anomalous thermal activity. Ridge subduction may play a crucial role in the evolution and growth of the continental crust in Central Asia.

The ability to abandon old strategies and adopt new ones is essential for survival in a constantly changing environment. While previous studies suggest the importance of the prefrontal cortex and some subcortical areas in the generation of strategy-switching flexibility, the fine neural circuitry and receptor mechanisms involved are not fully understood. In this study, we showed that optogenetic excitation and inhibition of the prelimbic cortex-nucleus accumbens (NAc) pathway in the mouse respectively enhances and suppresses strategy-switching ability in a cross-modal spatial-egocentric task. This ability is dependent on an intact dopaminergic tone in the NAc, as local dopamine denervation impaired the performance of the animal in the switching of tasks. In addition, based on a brain-slice preparation obtained from Drd2-EGFP BAC transgenic mice, we demonstrated direct innervation of D2 receptor-expressing medium spiny neurons (D2-MSNs) in the NAc by prelimbic cortical neurons, which is under the regulation by presynaptic dopamine receptors. While presynaptic D1-type receptor activation enhances the glutamatergic transmission from the prelimbic cortex to D2-MSNs, D2-type receptor activation suppresses this synaptic connection. Furthermore, manipulation of this pathway by optogenetic activation or administration of a D1-type agonist or a D2-type antagonist could restore impaired task-switching flexibility in mice with local NAc dopamine depletion; this restoration is consistent with the effects of knocking down the expression of specific dopamine receptors in the pathway. Our results point to a critical role of a specific prelimbic cortex-NAc subpathway in mediating strategy abandoning, allowing the switching from one strategy to another in problem solving.

The Ider Complex of the Tarbagatai Block in northwestern Mongolia is part of a Precambrian microcontinental terrane in the Central Asian Orogen Belt and has experienced a polymetamorphic tectono-metamorphic evolution. We have investigated an enderbitic gneiss, derived from a quartz diorite and a charnockite, derived from a leucogranite, and zircon SHRIMP data reveal late Archaean protolith ages of 2520–2546 Ma for these rocks. Metamorphic overgrowth on these zircons as well as newly-formed metamorphic zircons document a high-temperature metamorphic event (T = 930–950 °C) at about 1855–1860 Ma. Nd whole-rock isotopic systematics show these and other gneisses of the Ider Complex straddling the CHUR-line in a Nd isotope evolution diagram, suggesting both crustal reworking and input of some juvenile material, with Nd model ages ranging between ca. 2.5 and 3.1 Ga. Hf-in-zircon isotopic data provide a similar pattern and also yielded Archaean Hf crustal model ages. The metamorphic zircons seem to have inherited their Hf isotopic composition from the igneous grains, suggesting a complex process of dissolution, transportation, and re-precipitation involving a fluid phase during high-grade metamorphism. The zircon age patterns do not make it possible to unambiguously assign the Tarbagatai Block to any of the cratons bordering the Central Asian Orogenic Belt, since age peaks at ca. 2520–2550 and ca. 1860 Ma are common in the Siberian, North China and Tarim cratons.

SHRIMP dating of magmatic zircons from granitoid gneisses and charnockites of the Trivandrum and Nagercoil Blocks in the granulite terrane of southernmost India yielded well-defined protolith emplacement ages between 1765 and ca. 2100 Ma and also document variable recrystallization and/or lead-loss during the late Neoproterozoic Pan-African event at around 540 Ma. Hf-in-zircon and whole rock Nd isotopic data suggest that the granitoid host rocks were derived from mixed crustal sources, and Hf–Nd model ages vary between 2.2 and 2.8 Ga. A gabbroic dyke, emplaced into a charnockite protolith and deformed together with it, only contained metamorphic zircon whose mean age of 542.3 ± 4.0 Ma reflects the peak of granulite–facies metamorphism during the Pan-African high-grade event. The Sm–Nd whole-rock isotopic system of several granitoid samples dated in this study was significantly disturbed during granulite–facies metamorphism, most likely due to a CO 2 -rich fluid phase. Whole-rock Nd model ages are consistently older than zircon-derived Hf model ages. The Trivandrum and Nagercoil Blocks are reinterpreted as a single tectono-metamorphic terrane predominantly consisting of Palaeoproterozoic granitoids interlayered with supracrustal rocks that must be older than ca. 2100 Ma. Ductile deformation, migmatization and anatexis have obliterated the original rock relationships. These blocks probably have their counterpart in the Highland Complex of neighbouring Sri Lanka and in the high-grade Palaeoproterozoic terrane of southern Madagascar. We speculate that the southern Indian khondalites may have their counterparts in the khondalite belt of the North China Craton.

We report detrital zircon ages for Precambrian and early Palaeozoic metasediments from the Tianshan orogen in Kyrgyzstan, an important component of the Central Asian Orogenic Belt and compare these with published ages from the Chinese Tianshan and the Tarim craton. These data provide information on possible source terrains and suggest that Precambrian basement is widespread in the Tianshan and may, at least in part, represent continental fragments rifted off the Tarim craton during the early history of the Central Asian Orogenic Belt. Distinct differences in the Precambrian zircon age distribution between the North and Middle Tianshan of Kyrgyzstan support earlier ideas that these two terranes had different crustal histories prior to their amalgamation in the early Palaeozoic. We envisage an archipelago-type scenario for the Palaeo-Asian Ocean south of the Siberian craton in the late Neoproterozoic to early Palaeozoic in which numerous island arcs and Precambrian crustal fragments derived from Tarim drifted northwards (in present coordinates) and were amalgamated and tectonically stacked together during several ocean closure and accretion–collision events. This is surprisingly similar to what has been envisaged for the evolution of Indonesia where Mesozoic rifting of fragments from the Australian margin was followed by Cretaceous collisions and Cenozoic collision of Australia with the SE Asian margin. In both Central Asia and Indonesia continental crust has arrived in the region in multiple episodes and has been fragmented and juxtaposed by subduction-related processes. Continental growth during this process was minimal.

The precise age of the volcano-sedimentary Soutpansberg Group, which was deposited upon the Palala shear belt separating the Kaapvaal Craton from the Central Zone of the Limpopo Belt, has long been debated. The Soutpansberg Group is subdivided into a lower and upper succession, which are separated from each other by a prominent regional unconformity. Zircon grains from silicic pyroclastic rocks of both successions were investigated in order to constrain the timing of deposition of the Soutpansberg Group rocks. The zircon grains of the investigated samples from both successions yield a wide range of ages, spanning from 1831 to 3937 Ma. Most of the zircon grains have rounded shapes, however it is not clear whether they are mainly xenocrystic or detrital, or have been rounded by resorption in a silicic magma chamber. The youngest zircon grain ages obtained come from the lower succession and are 1832 ± 9 and 1831 ± 15 Ma. We interpret these youngest zircon grains as magmatic grains that have been rounded by resorption. This view is corroborated by the fact that no magmatic rocks of this particular age have been observed in the Kaapvaal Craton or the Central Zone of the Limpopo Belt, and that no apparent sedimentary admixtures are present in the well exposed pyroclastic rocks. We therefore conclude that deposition of the Soutpansberg volcano-sedimentary succession commenced around 1830 Ma. The Soutpansberg rocks were deposited apparently over a lengthy period of time (ca. 230 Ma), as provided by the published age of 1604 Ma for pyroclastic rocks of the upper succession in Botswana. Zircon grain age spectra of our Soutpansberg samples show prominent peaks at 2.0, 2.6 and 3.2 Ga, indicating the Central Zone of the Limpopo Belt as the source area, but excludes the adjacent northern part of the Kaapvaal Craton. The oldest zircon grain identified in the Soutpansberg samples has an age of 3937 ± 4 Ma, one of the oldest zircon grain ages yet reported from the African continent.

The South China Block (SCB) is composed of the Yangtze Block in the northwest and the Cathysia Block in the southeast. The earliest Neoproterozoic granitic rocks in the SCB are important for our understanding of the tectonic regime and location of this ancient continent in relation to the Rodinia supercontinent. However, such rocks have rarely been reported for the Cathaysia Block so far. In this study, six granitic gneisses from the Wuyi-Yunkai domain gave zircon U–Pb ages of 985–913 Ma, indicating the presence of the early Neoproterozoic granitic magmatism in the Cathaysia interior. These granitic gneisses are peraluminous with high FeOt, MgO, TiO 2 and CaO/Na 2 O but low SiO 2 , Al 2 O 3 /TiO 2 , Al 2 O 3 /(MgO + FeOt) and Rb/Sr ratios. They show steep REE chondrite-normalized patterns with δEu values of 0.35–0.70. These samples have strongly negative Ba, Sr, Nb-Ta, P and Ti anomalies in primitive mantle-normalized diagrams, and ɛNd( t ) values of −9.54 to −3.81, similar to those of the Kwangsian granitic rocks and Precambrian volcanosedimentary package in the Cathysia Block. The zircon grains with the earliest Neoproterozoic age gave ɛHf(t) values of −9.64 to +2.78 with the peak values at −2.5 and −7.5, and Hf model ages of 1.35–2.00 Ga with the two-peaks of 1.57 Ga and 1.75 Ga, respectively. These data suggest that the granitic gneisses originated dominantly from a binary mixing of metapelitic and metaigneous components, with insignificant input of juvenile materials. We consider that these rocks are closely related to the closure of the earliest Neoproterozoic (∼980 Ma) Wuyi-Yunkai back-arc basin in an accretionary continental margin setting. In combination with other data, it is proposed that the previously-defined Cathaysia block might consist of various sub-blocks separated by the arc-back-arc basin prior to the early Neoproterozoic period. The Wuyi-Yunkai arc-back-arc system was finally closed at ∼920 Ma, significantly younger than the classical Grenvillian Orogenic event, and thus the SCB was located on the margin of the Rodinia supercontinent.

The metamorphosed Early Paleoproterozoic granitoids in the Quanji massif, Northwestern China provide constraints for relationship between the Tarim Craton and North China Craton. Among granitoids batholiths, rocks of the Mohe quartz-diorite show typically adakitic geochemical characteristics, with medium K2O/Na2O ratios (0.56–1.17) and high Sr (519–619 ppm) low Y (9.37–20.40 ppm) and Yb (0.97–1.77 ppm) concentrations. The rocks have ɛ Nd(t) values between +2.4 and +4.4 and depleted mantle Nd model ages of 2.43–2.59 Ga. The magmatic zircons have positive ɛ Hf(t) values ranging from +0.40 to +7.60 and depleted mantle Hf model ages of 2.43–2.70 Ga, with major peaks at ∼2.54 and ∼2.65 Ga. The geochemical and Nd-Hf isotopic characteristics indicate that the Mohe quartz-dioritic rocks might be formed by partial melting of high-pressure metamorphosed juvenile crustal rocks in post-orogenic extensional regime in the Early Paleoproterozoic. It suggests that important crustal growth occurred in the Quanji massif and the Tarim Craton at ∼2.4 and 2.5–2.7 Ga. The Quanji massif and Tarim Craton might share a similar crustal evolution history with the North China Craton in the Neoarchean.

This study reports new zircon U–Pb and Hf isotopes and whole-rock elemental and Sr–Nd isotopic data for the gneissic granite and leucogranite from the Nabang metamorphic zone, Yingjiang area (West Yunnan, SW China). The metamorphosed granitoids crystallized during the early Eocene (~ 55–50 Ma) with zircons showing eHf(t) values from + 11 to − 5.3 and crustal model ages of 1.5 to 0.42 Ga, comparable to those of coeval I-type granitoids from the Gangdese batholith, southern Lhasa. The rocks are characterized by metaluminous and weakly peraluminous hornblende-bearing gneissic granites with A/CNK = 0.95–1.09, Na2O > K2O, coupled with low initial Sr isotopic values of 0.7049–0.7070 and high eNd(t) values from + 1.1 to − 7.1. The rocks were derived from crustal materials involving ancient upper crust/sedimentary and juvenile mantle-derived rocks. Together with available data from nearby regions, it is proposed that the early Eocene granitoids in the Nabang and Tengliang area can be correlated to the Gangdese granitoids and represent the southeastward continuation of the magmatic arc resulting from the Neotethyan subduction in southern Tibet. The petrogenesis of early Eocene granitoids in western Yunnan was probably related to the rollback of the subducting Neotethyan slab that caused the remelting of the crustal materials newly modified by the underplated basaltic magma.

A comparative geochemical characteristics of Late Precambrian sedimentary rocks (Ust’-Kelyana and Tuluya rock units) in the Anamakit–Muya zone of the Baikal–Muya belt is given, and the conditions of their sedimentation are considered. The first results of U–Pb (LA-ICP-MS) dating of detrital zircons and Sm–Nd isotope data on the Tuluya unit deposits are presented. Petrogeochemical study showed that the studied sediments are first-cycle rocks similar in composition to terrigenous island-arc sediments. The low contents of Th, Rb, Zr, Hf, and LREE and high contents of Co, Ni, Sc, V, Cr, and Fe2O3* in the sandstones of the Ust’-Kelyana unit evidence that these rocks are similar to oceanic-arc deposits. In contrast, the enrichment of the Tuluya unit rocks in Zr, LREE, Th, Rb, and Nb indicates their similarity to deposits of continental island arcs or active continental margin. Isotope-geochronological studies of the Tuluya rock unit showed the mixing of detrital material resulted from the erosion of Neoproterozoic island-arc igneous rock associations (625–700 Ma), like those in the Karalon–Mamakan zone (Yakor’ and Karalon Formations), and more ancient associations, like the Kelyana (812–824 Ma) and/or Dzhaltuk Groups. Judging from the minimum age of detrital zircon, the lower time bound of sedimentation corresponds to 0.6 Ga.

Packages of Late Paleozoic tectonic nappes and associated major NE-trending strike-slip faults are widely developed in the Altai–Sayan folded area. Fragments of early deformational phases are preserved within the Late Paleozoic allochthons and autochthons. Caledonian fold-nappe and strike-slip structures, as well as accompanying metamorphism and granitization in the region, are typical of the EW-trending suture-shear zone separating the composite Kazakhstan–Baikal continent and Siberia. In the Gorny Altai region, the Late Paleozoic nappes envelop the autochthon, which contains a fragment of the Vendian–Cambrian Kuznetsk–Altai island arc with accretionary wedges of the Biya–Katun’ and Kurai zones. The fold-nappe deformations within the latter zones occurred during the Late Cambrian (Salairian) and can thus be considered Salairian orogenic phases. The Salairian fold-nappe structure is stratigraphically overlain by a thick (up to 15 km) well-stratified rock unit of the Anyui–Chuya zone, which is composed of Middle Cambrian–Early Ordovician fore-arc basin rocks unconformably overlain by Ordovician–Early Devonian carbonate-terrigenous passive-margin sequences. These rocks are crosscut by intrusions and overlain by a volcanosedimentary unit of the Devonian active margin. The top of the section is marked by Famennian–Visean molasse deposits onlapping onto Devonian rocks. The molasse deposits accumulated above a major unconformity reflects a major Late Paleozoic phase of folding, which is most pronounced in deformations at the edges of the autochthon, nearby the Kaim, Charysh–Terekta, and Teletskoe–Kurai fault nappe zones. Upper Carboniferous coal-bearing molasse deposits are preserved as tectonic wedges within the Charysh–Terekta and Teletskoe–Kurai fault nappe zones. Detrital zircon ages from Middle Cambrian–Early Ordovician rocks of the Anyui–Chuya fore-arc zone indicate that they were primarily derived from Upper Neoproterozoic–Cambrian igneous rocks of the Kuznetsk–Altai island arc or, to a lesser extent, from an Ordovician–Early Devonian passive margin. A minor age population is represented by Paleoproterozoic grains, which was probably sourced from the Siberian craton. Zircons from the Late Carboniferous molasse deposits have much wider age spectra, ranging from Middle Devonian–Early Carboniferous to Late Ordovician–Early Silurian, Cambrian–Early Ordovician, Mesoproterozoic, Early–Middle Proterozoic, and early Paleoproterozoic. These ages are consistent with the ages of igneous and metamorphic rocks of the composite Kazakhstan–Baikal continent, which includes the Tuva-Mongolian island arc with accreted Gondwanan blocks, and a Caledonian suture-shear zone in the north. Our results suggest that the Altai–Sayan region is represented by a complex aggregate of units of different geodynamic affinity. On the one hand, these are continental margin rocks of western Siberia, containing only remnants of oceanic crust embedded in accretionary structures. On the other hand, they are represented by the Kazakhstan–Baikal continent composed of fragments of Gondwanan continental blocks. In the Early–Middle Paleozoic, they were separated by the Ob’–Zaisan oceanic basin, whose fragments are preserved in the Caledonian suture-shear zone. The movements during the Late Paleozoic occurred along older, reactivated structures and produced the large intracontinental Central Asian orogen, which is interpreted to be a far-field effect of the colliding East European, Siberian, and Kazakhstan–Baikal continents.

The ca. 1.0–1.1 Ga Vijayan Complex (VC) of eastern and southeastern Sri Lanka is one of three high-grade metamorphic terranes making up the basement of the island and is in tectonic contact with the adjacent, older Highland Complex. It consists predominantly of granitoid gneisses ranging in composition from diorite to leucogranite, with a distinct calc-alkaline geochemical signature, and is interpreted as a magmatic arc. Strong ductile deformation has obliterated almost all original intrusive relationships. High-grade metamorphism during the Pan-African event at ca. 610–520 Ma has produced widespread granulite-facies assemblages that are now largely retrogressed and were affected by extensive late metamorphic K-metasomatism. In southern Sri Lanka the Vijayan gneisses are tectonically interlayered with rocks of the Highland Complex in a so-called mixed zone. We report zircon ages, whole-rock Nd and Hf-in-zircon isotopic systematics and geochemical data for a large selection of Vijayan gneissses in order to better characterize this complex and its tectonic setting. The zircon ages are predominantly in the range 1100–1000 Ma with a few early Neoproterozoic intrusions, and identify the VC as a Grenville-age magmatic arc. Many zircons experienced minor to significant lead-loss at about 580 Ma. The Nd and Hf isotopic data confirm a generally primitive origin for most Vijayan gneisses, but significant variations in both isotopic systems argue for source heterogeneities and the possible involvement of minor amounts of older continental material in their genesis. Immobile trace and rare earth element distributions favour an origin of the gneiss protoliths through melting at relatively shallow depth, and the chemical variation from diorite and tonalite via granodiorite to granite in the VC can be explained by increasing fractionation of plagioclase and biotite, accompanied by amphibole and accessory phases. The VC may be comparable, in some respect, to the composition and evolution of the Kohistan Arc in Pakistan. The unique composition, age and isotopic characteristics of the VC find no convincing counterpart in other fragments of the Gondwana supercontinent, and its origin therefore remains exotic and enigmatic.

The Late Carboniferous to Early Permian is a critical period for the formation of particular high-temperature magmatic associations in West Junggar, NW China and the geodynamic processes of ridge subduction and related slab windows in the Central Asian Orogenic Belt. Mafic to intermediate dikes, exposed in the central and southeastern West Junggar extensively, mainly consist of Nb-enriched and magnesian suites. The Nb-enriched dikes (305 Ma) are characterized by high Nb contents (5.63–9.08 ppm) and large variations of major element contents, exhibiting high-K to medium-K calc-alkaline characteristics with high Na2O/K2O (1.33–3.85) and low Sr/Y (9–32) ratios. The dikes have moderate Mg# (44.6–52.9), LREE-rich and sub-horizontal HREE patterns ((La/Yb)N = 3.05–7.18; (Gd/Yb)N = 1.43–1.78) with weak Eu anomalies (Eu⁎/Eu = 0.81–1.10) and positive eNd (t) values (+ 5.2 to + 8.0), and likely originate from partial melting of mantle peridotite that was metasomatized by subducted sediment-derived melts and slab fluids. The medium-K magnesian dikes (305 Ma) are characterized by high MgO (3.05–7.28 wt.%), Cr (22.3–311 ppm) and Ni (32.6–199 ppm) contents and all plot in the field of high-Mg andesite. Some have very high Mg numbers (Mg# > 60), suggesting a primitive melt composition. These samples display positive Ba, Sr, K and negative Nb–Ta–Ti anomalies as well as strongly-depleted HREE patterns with weak positive Eu anomalies. They have high Sr/Y (27–126) and relatively high eNd (t) values (+ 6.0 to + 8.3), which suggest a similar petrogenesis as the Nb-enriched dikes, but were metasomatized by adakitic melts. The high-K magnesian dikes (284 Ma) are high-K calc-alkaline and have lower MgO (3.63–5.57 wt.%) compared with the medium-K suite. They have high Sr (422–819 ppm), Sr/Y (26–62) ratios and eNd (t) values (+ 7.0 to + 7.1) with relatively flat REE patterns ((La/Yb)N = 2.4–5.5), probably originating from partial melting of K-enriched mantle wedge peridotite metasomatized by adakitic slab melts. Based on these petrogenetic features, we suggest that a ridge subduction regime likely prevailed in West Junggar in the Late Carboniferous. The opening of related slab windows and upwelling asthenosphere have possibly triggered the formation of Late Carboniferous–Early Permian magmatic associations in West Junggar.

The Neoproterozoic mafic rocks of the Jiangnan Orogen in South China provide a critical geological record for unraveling regional tectonic history and testing different tectonic models. However, the geochronology, geochemistry and petrogenesis of >835 Ma mafic igneous rocks in the Central and Southwestern Jiangnan Orogen have not been well reported so far, in contrast to the extensive study of such rocks in the Eastern Jiangnan Orogen. An integrated study of geochronology and geochemistry has been carried out for the basaltic rocks from NE Hunan and NW Jiangxi Provinces of the Central Jiangnan Orogen. SHRIMP, SIMS and LA-ICP-MS zircon U–Pb dating of three mafic samples yielded zircon U–Pb ages of 860 ± 20 Ma, 838 ± 12 Ma and 847 ± 18 Ma, respectively. This provides evidence for the development of early Neoproterozoic (∼850 Ma) mafic lava along the Central Jiangnan Orogen. SiO2 ranges from 49.43 wt% to 52.07 wt% and MgO from 7.36 wt% to 9.04 wt% with mg-number of 68–57. Their chondrite-normalized REE patterns exhibit a left-sloping pattern with more depleted LREEs relative to HREEs. On the N-MORB-normalized multi-element patterns, they are characterized by enriched highly incompatible elements, depleted moderately incompatible elements relative to those in N-MORB, insignificant Nb–Ta depletion and remarkably positive Sr and weakly negative Ti anomalies, resembling those of modern Eastern Lau back-arc basin basalts. In addition, these rocks have positive ɛNd(t) values of 1.30–9.36 with initial 87Sr/86Sr ratios in the range of 0.70796–0.71126. The geochemical characteristics above indicate an origination of the MORB-like source modified by the flux of the slab-derived fluid and input of the recycled sediment-derived melt. This finding, together with other geological observations, suggests that the mafic rocks in the Central Jiangnan Orogen might be formed in a back-arc basin in the eastern SCB. In conjunction with other data, it is inferred that the closure of the back-arc basin along the Central Jiangnan Orogen is contemporaneous with that in the Fuchuan area.

The Quanji (全吉) Massif is located in the Northwest China, which is interpreted as a micro-continent that is composed of metamorphic basement and stable cover strata. There are some controversies of genetic relationship between the Quanji Massif and the major cratons in China. In this study, we obtained in situ zircon U-Pb and Hf isotopic compositions of the Yingfeng (鹰峰) rapakivi granites from the northwest Quanji Massif by application of LA-MC-ICP-MS technique. Twenty U-Pb age measurements points are concordant or near concordant, and their weighted mean 207Pb/206Pb age is 1 793.9±6.4 Ma (MSWD= 1.09), yields an upper intercept age of 1 800±17 Ma (MSWD=0.41); 19 Hf isotope measurements yield a two-stage Hf model ages (T DM2) of 2.63 to 2.81 Ga, with a weighted average age of about 2.70±0.02 Ga and ɛHf(t) values variate between -8.91 to -5.35. This indicates that magma source of the Yingfeng rapakivi granites were produced from partial melting of late stage of Neoarchean juvenile crust, and suggests a significant crustal growth event occurred in the Quanji Massif at that time. The Quanji Massif might be an ancient continental segment detached from the Tarim Craton based on the crustal growth history and other geological records. The Tarim Craton (including the Quanji Massif) and the North China Craton had a similar or homological early crustal evolution around ∼2.7 Ga, which implies that Tarim Craton might be one of the component parts of North China Craton.