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The West Qinling Orogen (WQO), which is bounded by the Qilian Orogenic Belt, Qaidam Block and the Songpan-Ganzi Block, is the western extension of the Qinling Orogenic Belt, and experienced complex tectonic evolution processes, involving the opening, subduction and closure history of the Proto- and Paleo-Tethys Oceans. The WQO features widespread Indosinian magmatic rocks, which are crucial to constrain the tectonic evolution of the WQO. The Indosinian magmatic rocks were formed mainly in two stages, 250 to 240 Ma and 225 to 210 Ma. The Early Indosinian magmatic rocks (250 to 240 Ma) are mainly distributed in the west and middle northern WQO. In comparison, the Late Indosinian magmatic rocks are mainly exposed in the eastern WQO, but also in the western WQO and the Bikou terrane. Controversy has existed for a long time on the petrogenesis and tectonic setting of the Early Indosinian magmatic rocks. We selected four respective plutons, including the Heimahe pluton, the Ren’ai pluton, the Daerzang pluton and the Ganjiagongma pluton. Detailed field investigation, petrology, LA-ICP-MS zircon U-Pb dating, zircon Lu-Hf isotope analyses, whole rock geochemistry and Sr-Nd isotope analyses, and mineral EPMA analyses were conducted for the studied plutons. The studied plutons were emplaced between 246 to 241 Ma according to zircon U-Pb dating results. Based on detailed studies on petrology, geochronology and geochemistry, we emphasis the significance of magma mixing in the petrogenesis of the Early Indosinian granitic rocks. The high Mg# signature of the Early Indosinian granitic rocks were generated by magma mixing between mafic and felsic magmas, but not result of direct fractional crystallization of mafic rocks. The granitic rocks with high Sr/Y values in the WQO, represented by the Ganjiagongma pluton, were not derived from thickened continental crust. No evident continental thickening occurred in the WQO during the Early Indosinian. Combining with regional geological evidence, we propose an alternative tectonic model to explain the evolution history of the WQO during the early Mesozoic. The A’nimaque-Mianlue ocean subducted northward with low angle, then the subducted slab rolled back during the Late Permian to Middle Triassic, and the ocean closured in the Late Triassic. This model can explain the spatial and temporal distribution characteristics of the magmatic rocks and sedimentary rocks, as well as Late Triassic uplift and deformation event in the WQO.

The East Kunlun Orogen on the northern margin of the Tethyan orogenic system records a history of Gondwana dispersal and Laurasian accretion. Based on a synthesis of sedimentary, structural, lithological, geochemical, and geochronological data from the East Kunlun Orogen and adjacent regions, we discusses the spreading and northward consumption of the Paleo-Tethys Ocean during Late Paleozoic-Early Mesozoic times. The main evolutionary stages are: (1) During Carboniferous to Middle Permian, the Paleo-Tethys Ocean (Buqingshan Ocean) was in an ocean spreading stage, as suggested by the occurrence of Carboniferous MORB-, and OIB-type oceanic units and Carboniferous to Middle Permian Passive continental margin deposits; (2) The Buqingshan Ocean subducted northward beneath the East Kunlun Terrane, leading to the development of a large continental magmatic arc (Burhan Budai arc) and forearc basin between ~270-240 Ma; (3) During the late Middle Triassic to early Late Triassic (ca. 240-230 Ma), the Qiangtang terrane collided with the East Kunlun-Qaidam terranes, leading to the final closure of the Buqingshan Ocean and occurrences of minor collision-type magmatism and potentially inception of the Bayan Har foreland basin; (4) Finally, the East Kunlun Orogen evolved into a postcollisional stage and produced major magmatic flare-ups and polymetallic mineral deposits between Late Triassic to Early Jurassic (ca. 230-200 Ma), which is possibly related to asthenospheric mantle upwelling induced by delamination of thickened continental lithosphere and partial melting of the lower crust. Accordingly, we propose that the Wilson cycle-like processes controlled the Late Paleozoic-Early Triassic tectonic evolution of East Kunlun, which provides significant implications for the evolution of Paleo-Tethys Ocean.

The Qingshuiquan-Tatuo ophiolites (QTOs), which are located in the central fault of the Kunlun Orogen, can provide critical information regarding the subduction processes of the Proto-Tethys Ocean. This study presents petrological, whole-rock geochemical, Sr Nd isotopic, and zircon U Pb data on these ophiolites. The QTOs consist of mantle peridotites, pyroxenites, and fine-grained low- and high-Ti (alkaline) gabbros (LTGs and HTGs, respectively) and lack mafic lava units. The QTO mafic units can be geochemically subdivided into LTGs and HTGs. The LTGs have high MgO contents (mostly >8.0%), V/Ti ratios (37.41–158.77) and low TiO2 (mostly Pb data yield a crystallization age of 516 Ma for the LTGs. In contrast, the HTGs show relatively high total alkali (1.72–5.66%), TiO2 (1.45–3.68%) and REE contents, high (La/Yb)N (3.37–14.06), Ti/Y (290.78–1058.94), and low ɛNd(t) values (−3.02 to −3.55), which suggest a geochemical signature of oceanic island basalt (OIB) and continental rift-like basalt. The zircon U Pb data yield crystallization ages of 486–485 Ma for the HTGs. Petrogenetic analyses suggest that the LTGs were derived from remelting of forearc mantle peridotites and that the serpentinites (harzburgites) represent the forearc mantle after the extraction of low-Ti mafic melts. In contrast, the HTGs were derived from a fertile asthenospheric mantle upwelling through a slab window followed by minor subcontinental lithospheric mantle (SCLM)/crust contamination. The findings suggest that the QTOs were generated in an epicontinental environment above the subduction zone, which was geodynamically related to slab rollback at 516 Ma and subsequent oceanic-ridge oblique subduction at 485 Ma.

Indosinian granitic rocks are widespread in the West Qinling Orogen (WQO) in central China. Some of the early Indosinian granitoids have high Sr and low Y contents, and therefore high Sr/Y ratios, and they have been interpreted as adakitic rocks that formed by partial melting of thickened continental lower crust. However, several studies have revealed that granitoids with high Sr/Y ratios can be formed by various geological processes. Here, we report new zircon U-Pb ages, whole–rock geochemical data, and Sr–Nd–Hf isotope data for the Ganjiagongma pluton in the Xiahe area of the WQO, and we discuss whether the WQO underwent crustal thickening during the early Indosinian. The zircon U-Pb dating results indicate that the Ganjiagongma granodiorite and its mafic microgranular enclaves (MMEs) crystallized at ca 242 Ma. The MMEs are characterized by low SiO2 contents and Sr/Y ratios, and high MgO, Cr, and Ni contents, as well as high Mg# values, and they have evolved zircon Hf and whole–rock Sr-Nd isotopes, indicating they were produced by the partial melting of metasomatized continental lithospheric mantle. The granodiorite samples have some adakitic characteristics with SiO2 = 65.22 to 68.01 wt%, MgO = 1.07 to 1.71 wt%, Mg# = 59 to 62, Sr = 357 to 620 ppm, Y = 9.7 to 17.4 ppm, Sr/Y = 30.26 to 47.46, and no significant Eu anomalies. However, the granodiorites have relatively flat HREE patterns, indicating that amphibole, rather than garnet was the main residue in the source area, and this proposal is consistent with the relatively low but constant Nb/Ta values and varied Zr/Sm ratios. Simple two-end member modeling results indicate that the granodiorite could have been formed in normal or slightly thickened crust by mixing of 20%–30% mantle-derived melt with 70%–80% melt derived from the partial melting of basement rocks in the continental lower crust of the WQO. Taking into account other geological evidence, we propose that the formation of the Ganjiagongma pluton was related to the subduction of the A'nimaque-Mianlue oceanic crust, and that no significant thickening of the continental crust occurred in the WQO during the early Indosinian.

Early Palaeozoic ophiolites emplaced in the central East Kunlun fault zone (CEKF) offer critical clues to the tectonic evolution of the Proto-Tethys ocean and the accretionary process of CEKF. The Qushi'ang Ophiolite, located within the eastern segment of the CEKF, consists of dismembered serpentinites, meta-gabbros and meta-basalts. This study presents petrologic, whole-rock geochemical, and in situ zircon U-Pb and Hf isotope data for basic rocks (both metagabbros and metabasalts) from the Qushi'ang ophiolite to constrain the formation age and tectonic setting of the ophiolite. Zircons from two meta-gabbro samples yield concordant U-Pb ages of ca. 498 Ma and ca. 505 Ma, indicating that the Qushi'ang ophiolite was formed in the late Cambrian. The meta-gabbros and meta-basalts show significant enrichment in large ionic lithophile elements (LILEs), such as Cs, Rb, Ba, U, and Pb, and depletion in high field strength elements (HFSEs), such as Nb, Ta, Zr, and Ti, suggesting the influence of fluids derived from a subducting oceanic slab. On the N-MORB normalized trace element diagrams, these rocks share similar features with arc basalts and back-arc basalts and far away from fore-arc basalts (FABs) and normal mid-ocean basalts (N-MORBs). Low zircon eHf(t) values (−2.9 to +0.2) for the meta-gabbros further indicate that the Qushi'ang ophiolite likely originated from an weakly enriched mantle wedge source. Geochemical discrimination diagrams show that the Qushi'ang ophiolite formed in a back arc basin setting. Our new analyses, combined with previous data, suggest that the Qushi'ang ophiolite represents a relict of a nascent back-arc basin, similar to the scenario of the Okinawa trough in Western Pacific.

The Central Kunlun ophiolitic melange zone, northern Tibetan Plateau, represents a remnant of the Early Paleozoic oceanic lithosphere. The Middle Ordovician Longshigeng basalts (LBs) are located in south of this melange zone and have important significance for reconstructing the opening and subduction processes of the Proto-Tethys Ocean. This study presents petrological, whole-rock geochemical, and zircon U-Pb data for these basalts. LA-ICP-MS U-Pb zircon data indicate that these basalts formed ca. 463 Ma. Geochemically, the basalts are characterized by low SiO2 (47.00–50.63 wt%) and K2O (0.22–1.05 wt%), intermediate Mg# (47–57) and high TiO2 (1.51–2.72 wt%), and are identified as tholeiitic basalts. Their chondrite-normalized REE patterns feature slight enrichments in LREEs (LREE/HREE = 2.11–3.08) with mild Eu anomalies (δEu = 0.89–1.06), and their patterns are similar to the reference line of enriched mid-ocean ridge basalt (EMORB). The primitive mantle-normalized trace element diagrams also show similarities with EMORB and are characterized by overall enrichments in large ion lithophile and high field strength elements, without notable Nb, Ta, and Ti depletions. Combining these data with the tectonic discrimination diagrams, we infer that these rocks formed in a back-arc environment in response to the northward subduction of the Proto-Tethys Ocean (South Kunlun Ocean) in the East Kunlun region, northern Tibetan Plateau.

Voluminous granitoids located in the East Kunlun orogen (EKO) play an important role in characterizing the crustal growth and northward subduction of the Paleo-Tethys oceanic lithosphere. This paper presents new petrological, whole-rock geochemical, zircon U-Pb isotope geochronological and Sr-Nd-Hf isotopic data for the Halagatu granitoids (HG) pluton. The HG pluton comprises several different textural and compositional types, i.e., medium- to fine-grained granodiorites (MG), porphyritic monzogranites (PMG), coarse-grained monzogranites (CMG), and dark mafic microgranular enclaves (ME). U-Pb dating of zircons from the HG pluton yielded a weighted mean 206Pb/238U age of 248–244 Ma, which represents the crystallization age of the HG pluton. The whole-rock geochemical data indicate that the PMG, CMG and MG have similar geochemical features; for example, they are classified as high-K calc-alkaline, metaluminous to wildly peraluminous I-type granitoids, with negative Nb-Ta and Ti anomalies, low Mg# and Al2O3/(FeOT + MgO + TiO2) values, and high Th/Y ratios. These characteristics suggest the parent magmas were crustally derived. In contrast, the ME are characterized by medium-K calc-alkaline and metaluminous compositions, low Th/Y ratios and relatively high Mg#, Cr, and Ni values, likely suggesting these magmas were derived from a mantle source. Furthermore, the host granodiorites and microgranular enclaves have consistent Sr-Nd-Hf isotopic features, with eNd(t) values of −6.10 to −4.30 and zircon eHf(t) values of −7.8 to −0.4, indicating an enriched subcontinental lithospheric mantle (SCLM). On the basis of these values and the whole-rock geochemistry, the HG pluton magmas were the result of mixing between lithospheric mantle-derived and crust-derived magmas and that fractional crystallization (FC) played an important role in the formation of the HG pluton. The combination of these new data with previously published data reveals that the HG pluton was emplaced in a continental magmatic arc setting by the northward subduction of a branch of the Paleo-Tethys Ocean (Buqingshan Ocean) beneath the East Kunlun-Qaidam terrane (EKT) and that the Buqingshan Ocean began to subduct strongly northward in the late Permian (ca. 260 Ma), with subduction terminating during the late Middle Triassic (ca. 240 Ma).

Freshwater sponges play a major role in freshwater ecological system as important filter-feeding organisms and bioindicators. There are only few data about their ecological diversity and population genetic structure available, though a deeper knowledge is needed to propose proper conservation and effective management. The aim of this study was to assess data on distribution patterns of freshwater sponges to study the connectivity of genotypes of Ephydatia fluviatilis in a river system. We sampled specimens from River-Sieg system (River Agger and River Sieg, Germany). We hypothesized that strong anthropogenic influence would cause a uniform distribution of population structures. The genetic structure of E. fluviatilis populations was analysed with a set of eleven microsatellite loci from seven locations in River-Sieg system. Besides of E. fluviatilis, three other species co-occurred (Ephydatia mulleri, Spongilla lacustris, Eunapius fragilis). In contrast to our hypothesis, we observed an overall correlation between genetic and geographic distances among populations of this sessile species, which follows a clear isolation-by-distance pattern. A significant microsatellite polymorphism and high levels of genetic divergence between populations (FST) in upstream reaches were present. These results will provide important information for conservation management of populations with limited dispersal ability in connected river systems.

The Acite ophiolitic melange represents a remnant of the Proto-Tethys forearc oceanic lithosphere. Two gabbros yield zircon 206Pb/238U ages of 510-512 Ma. The magmatic rocks are divided into three ...

The West Qinling Orogen (WQO) features widespread Triassic granitic rocks, which are crucial to constrain the tectonic evolution of the WQO. Here, we conducted an integrated petrological, geochronological, geochemical, and Sr-Nd-Hf isotope study on quartz diorites and mafic microgranular enclaves (MMEs) from the Ren’ai and Daerzang plutons, Hezuo area, WQO. The quartz diorites and MMEs have crystallization ages between 244 and 241 Ma. The quartz diorites display intermediate SiO2, high Mg# values (62–66) and evolved S-Nd-Hf isotope compositions, indicating an origin from magma mixing process. The MMEs display mineral compositions similar to those of the host rocks, only with more mafic minerals. The The Ren’ai and Daerzang plutons were part of the early Indosinian magmatic belt mainly distributed in the western and middle parts of the northern WQO. In comparison, late Indosinian magmatic rocks are mainly exposed in the eastern WQO. The asymmetric distribution of Early Mesozoic magmatism in the WQO might have been caused by a specific subduction pattern of the A’nimaque-Mianlue oceanic crust. The western and middle WQO experienced a period of flat or low angle subduction in the early stage, followed by slab rollback of the oceanic crust, which accounted for the flare-up of early Indosinian magmatism in the northern WQO. However, the distribution of late Indosinian magmatism might have been caused by asymmetric crustal delamination in the WQO.

The Neoproterozoic Hengdan Group in the northwestern margin of the Yangtze Block preserves archives for the debated early to middle Neoproterozoic (ca. 835–720 Ma) tectonic evolution of the margin of the Yangtze Block, and could potentially shed lights on the breakup mechanism of the Rodinia supercontinent. However, its depositional age, provenance and tectonic setting remain controversial. We address these issues through studies of petrography, geochemistry and detrital zircon U-Pb ages on the Hengdan Group sandstones. The Hengdan Group sandstones have low compositional and textural maturity and experienced low degree of chemical weathering and sediment recycling. They were mainly sourced from proximal acidic to intermediate arc-related igneous rocks, and their modal compositions, trace elemental contents (i.e., La, Ce, Th, and ΣREE) and ratios (i.e., LaN/YbN and Eu/Eu*) are comparable to those deposited in an active continental margin. Detrital zircons from the Hengdan Group sandstones yield similar unimodal age distributions at 950–740 Ma, with the youngest age clusters at ca. 730 Ma. Combining with previous work, the Hengdan Group was most likely deposited during ca. 733–717 Ma in a forearc basin and its primary provenance was probably from the nearby arc-related acidic to intermediate igneous rocks. In addition, the northwestern margin of the Yangtze Block was most likely in an active continental margin setting between ca. 835 and 720 Ma, and hence the slab retreating during a long-term oceanic subduction is favored as the dominant breakup driving force in the supercontinental margin(s).

A predominance of mantle peridotites over mafic rocks in the Tibetan Xigaze ophiolite distinguishes it from other classic ophiolites in the Tethyan belt, such as the Semail massif of Oman. Despite the abundance of new petrological, geochemical, geochronological and isotopic data on ophiolites that have accumulated over the last few decades, there is still no consensus on the tectonic setting and dynamic mechanisms of formation of these enigmatic bodies. This study involved detailed, large-scale mapping of the well-preserved Baimarang massif in the western part of the Xigaze ophiolite in order to provide key constraints on its tectonic setting.

The Buqingshan Tectonic Melange Belt in the south margin of the East Kunlun Orogen, located in west section of Buqingshan–A'nyemaqen Suture Zone, is one of the key areas to understand continental tectonics and continental dynamics of China. This paper reports zircon U–Pb dating results and geochemistry of the Manite granodiorite (rock mass) in the Buqingshan Tectonic Melange Belt. Zircons from the granodiorite show oscillatory zoning structures and relatively high Th/U ratios, indicating that they are magmatic zircons. Zircon LA–ICP–MS U–Pb dating for the Manite granodiorite yields ages of 487 ± 11 Ma (MSWD = 2.3) and 479 ± 2 Ma (MSWD = 0.56), implying that the Manite granodiorite were formed in the Late Cambrian to Early Ordovician. Geochemical analyses show that the rocks have high contents of SiO2 (66.06 wt.%–68.60 wt.%) and Al2O3 (14.84 wt.%–16.54 wt.%), and low alkaline (6.17 wt.%–7.43 wt.%), belonging to the middle-K calc-alkaline series. The A/CNK (Al2O3/(CaO + Na2O + K2O)) ratios are 1.02–1.15, indicating that the granodiorite is weakly peraluminous. The contents of rare earth elements (REEs) are lower (89.64–130.41 ppm), with weakly negative to weakly positive Eu anomalies (δEu = 0.83–1.12). The primitive mantle-normalized trace elements are characterized by evidently negative anomalies of Nb, Ta, P, Hf, Ti, etc., and positive anomalies of Th, La, Nd, Zr, Eu, etc. Moreover, the rocks show features of typical I-type granite. This leads us to conclude that the Manite granodiorites is derived from the partial melting of crust and formed in an island-arc environment. Combined with previous studies, we believe that the subduction of the Proto-Tethyan Ocean in the Buqingshan area was ongoing during 487 to 479 Ma and formed island-arc-type granites represented by the Late Cambrian to Early Ordovician Manite granodiorite. Copyright © 2016 John Wiley & Sons, Ltd.

The late Early Paleozoic volcanic rocks in the East Kunlun orogen are crucial to determining collisional processes related to the evolution of the Proto-Tethys Ocean. We report new zircon U-Pb ages, whole-rock geochemistry and Sr-Nd isotopes from these volcanic rocks and constrain their tectonic setting and magmatic processes. This volcanic suite consists mainly of foliated metarhyolites and minor metabasalts. Zircon U-Pb ages indicate that the bimodal volcanic rocks formed from Late Silurian to Early Devonian (ca. 420−409 Ma). The basalts show tholeiitic geochemical signatures characterized by low contents of SiO2 (47.19–54.83 %), MgO (2.21–7.52 %), and K2O/Na2O ratios (0.32−0.77%) and high contents of TiO2 (1.80–2.91 %). Their chondrite-normalized REE patterns are characterized by enrichments in LREEs (LREE/HREE = 3.68–6.09) with slight Eu anomalies (δEu = 0.67–1.00); their patterns are similar to the reference line of oceanic island basalt (OIB). The primitive mantle-normalized trace element diagram also shows similarities with OIBs and features overall enrichments in large ion lithophile and high field strength elements, except for Nb and Ta. The eNd(t = 422 Ma) values range narrowly from −1.79 to +1.32. These features suggest that the basalts were most likely derived from an asthenospheric mantle that was contaminated by small volumes of subcontinental lithospheric mantle (SCLM)/crust. The variations in major and trace elements show that the basalts experienced fractional crystallization of olivine, pyroxene and plagioclase. In contrast, the metarhyolites have high SiO2 (65.85–70.83 %), Na2O + K2O (6.71–10.09 %), K2O/Na2O ratios (1.69–2.80 %) and low MgO, Ni, and Cr contents. Their trace element signatures show enrichments in LILEs and LREEs (e.g. Cs, Rb, Ba), depletion of HFSEs (e.g. Nb, Ti, Ta) and high negative Eu anomalies. These features suggest a crustal origin lacking interactions with mantle melts. Considering all the geochemical and tectonic events of this area, it is concluded that the Maoniushan Formation volcanic rocks in EKOB formed in a postcollisional extensional setting related to asthenospheric mantle upwelling and continental delamination processes during the Late Silurian to Early Devonian. These tectonic-magmatic events, together with previous data, suggest that the Proto-Tethys Ocean had closed and evolved to postcollisional collapse stage since the Late Silurian.

The Yangtianba Formation in the northwestern Bikou Terrane preserves sedimentary archives for the Early to Middle Neoproterozoic tectonic evolution of the northwestern margin of the Yangtze Block (YB). However, its provenance and depositional mechanism are still matter of debates. This paper presents geochronological and petrographic studies of two granite gravel samples and one coarse-grained sandstone sample as well as facies analysis of the conspicuous Yangtianba Formation conglomerates (YFC). The weighted average 206Pb/238U ages of the two granite gravels are 743 ± 6 Ma and 762 ± 4 Ma, respectively. The detrital zircon U-Pb ages of the sandstone sample peak at ca. 880 to 740 Ma, close to the depositional age of the Yangtianba Formation. Together with the dominantly angular to subangular morphology and clear oscillatory or broad zoning of these detrital zircons, the Yangtianba Formation is likely sourced from the Early to Middle Neoproterozoic igneous rocks. Facies analysis of the YFC shows they are stacked bundles of fining- and thinning-upward units of conglomerates-sandstone, suggesting a decreasing supply of coarse clastic materials from the episodic mass flow (debris flow) in the submarine channels rather than tillites. Combining with the previous work, the Yangtianba Formation probably mainly sourced from the Neoproterozoic igneous rocks in the Micangshan-Hannan area in the northwestern margin of the YB and is subaqueous sediment gravity flow deposits rather than glacial-marine deposits. These findings favor the model that the northwestern margin of the YB may be an active continental margin setting during the Early- to Middle- Neoproterozoic (ca. 835 to 720 Ma).

The granite is one of most widely distribution rocks in crust, and its petrogenesis is crucial to advance our knowledge of thermal condition in continental crust. The long-time tectonic evolution of crust in the active continental margin could be recorded by multi-stages of granitic assemblage. In order to reveal the subduction of Neo-Tethys and initial collision of Indian-Asian continents in eastern Tibetan Plateau, we selected the Early Paleocene to Early Eocene granitic rocks with associated enclaves in Tengchong Block, southeastern extension of Gangdese magmatic belt, to clarify their different derivation regimes using geochemical and isotopic compositions, mineral compositional variation. The zircon data show that Early Paleocene granites formed at 64 Ma, and Early Eocene granitic rocks formed at 54 Ma. Combing with the field contact relationship, the similar and enriched Sr-Nd-Pb and zircon Hf isotopic compositions indicate that the two stages of granitic rocks have a common and ancient lower crustal source. The enclaves in Early Paleocene granites could represent crystallization of coeval and cognate magmas at margin of magmatic conduit, but the enclaves in Early Eocene granitic rocks are products of magma mixing between mafic and felsic magma. According to rock assemblages and geochemical signatures of granitic rocks during Early Paleocene to Early Eocene in Tengchong Block, we propose that Early Paleocene granitic rocks are derived from partial melting of lower crustal rocks induced by long-lived heat accumulation with no or minimal basalt flux during the Neo-Tethyan subduction, whereas Early Eocene granitic rocks are derived from melting of crustal materials resulted from high mafic magma flux during Indian-Asian continental collision. The initial collision occurred at ca. 55 Ma.

The Hengdan Group in the northwestern part of the Bikou Terrane preserves sedimentary archives for the debated early to middle Neoproterozoic tectonic evolution of the northwestern margin of the Yangtze Block (YB), while its depositional age, provenance and tectonic setting remain controversial. This research has reported the geochemical and geochronological studies on the sandstones in the Hengdan Group. Our work indicates that the sandstones in the Hengdan Group experienced low degree of chemical weathering and sedimentary recycling, and are mainly sourced from acidic to intermediate igneous rocks. In addition, their elemental contents (i.e., La, Ce, Th and ΣREE) and ratios (i.e., LaN/YbN and Eu/Eu*) are comparable to those deposited in an active continental margin setting. All samples yield similar age distribution, having a dominated age range at ca. 850 to 720 Ma. Together with the dominantly angular to subangular morphology and clear oscillatory or broad zoning internal structure of these aged detrital zircons, indicating that the Hengdan Group should be proximally sourced from the early to middle Neoproterozoic igneous rocks. In addition, the youngest group of detrital zircon U-Pb ages of the sandstones in the Hengdan Group suggest that the onset and ending of the deposition of this group is later than ca. 741 Ma and ca. 722 Ma, respectively. Combining with previous work, the Hengdan Group was most likely deposited during ca. 741 to 717 Ma in a forearc basin setting at the northwestern margin of the YB, and with its primary provenance probably from nearby acidic to intermediate igneous rocks. In addition, all these above further supports that the northwestern margin of the YB should be a long-lived active continental margin setting during early to middle Neoproterozoic (ca. 835 to 717 Ma) and, the South China Block should be located at the relative peripheral location of the Rodinia supercontinent.

As a new environmentally friendly liquid dielectric material, vegetable insulating oil has good fire-retardant and insulation properties, and it has been used in oil-immersed transformers more and more widely. Thermal ageing and thermal faults are usually occurred in transformers. During these processes the insulating oil and insulating paper will decompose, and gases will be generated and dissolve in the oil, then the dissolved gases formed. In this paper, the microcosmic molecular simulation of thermal decomposition of camellia insulating oil and insulating paper were studied. The molecular model system of camellia oil and insulation paper were established, the molecular dynamics (MD) simulation based on ReaxFF (Reactive Force-Field) was adopted to analyze the pyrolysis process of molecules in insulating oil and paper from 1400 K to 2200 K, and main gas products were obtained. Results showed that the increase of temperature and heating duration promoted the decomposition of the oil, and contents of characteristic gases were positively related to the temperature and the heating duration. C 2 H 6 was the main hydrocarbon gas of camellia insulating oil under thermal decomposition, in addition during the decomposition process there are lots of CO 2 and H 2 generated. H 2 O s the main product and CO 2 as well as CO are main gas products of insulating paper under thermal decomposition process. Finally gas production path and mechanism of camellia oil and insulating paper are obtained through atom tracking method.

Mid-Neoproterozoic rift-related Tadong amphibolites (TDA) are situated in the junction of the East Kunlun Orogen (EKO) and the West Qinling Orogen (WQO) in western China, and have important significance in the break-up of the Supercontinent Rodinia. The mineral assemblage of the TDA exhibits amphibolite facies metamorphism, and the protolith is basic volcanic rocks. Here, we present a detailed laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) zircon U–Pb age and geochemical data of TDA. LA-ICP-MS U–Pb zircon age determination indicates that the basic volcanics formed at ca. 743–711 Ma. Geochemically, TDAs are characterized by low SiO2 (46.06–50.18%), K2O (0.66–1.86%), and Mg# (40–45) and high TiO2 (1.9–3.5%), and are attributed to tholeiite basalts. Their chondrite-normalized REE patterns are characterized by moderate enrichments in LREEs (LREE/HREE = 4.98–5.51) with insignificant Eu anomalies (δEu = 0.99–1.12). The primitive mantle-normalized trace element diagrams are chara...

The Yikehalaer intrusives are distributed in the Buqingshan tectonic melange belt at the southern margin of East Kunlun, China. They tectonically intruded the conglomerate of Permian Gequ Formation to the south and the marble of Mesoproterozoic Kuhai Group to the north. These intrusives mainly consist of off-white coarse- and fine-grained granodiorite and granite. U–Pb dating of zircons from the intrusive samples yielded weighted mean 206Pb/238U ages of 436 ± 7 Ma and 437 ± 6 Ma, indicating Early Silurian crystallization age. The intrusives are high-silica, Na-rich, I-type calc-alkalic rocks. They are divisible into two subgroups on the basis of their trace element content: adakitic rocks in the northern part and normal calc-alkalic arc rocks in the southern part. Rocks in the northern part exhibit high Sr (280–493 ppm), low Y (3.8–11.7 ppm), high Sr/Y ratios (23.9–125.0), high light rare earth elements (LREE)/ heavy rare earth elements (HREE) (15.1–35.7), and invisible Eu/Eu∗. They resemble adakites formed by slab melting in subduction zones. However, the rocks in the southern part possess the attributes of normal arc rocks. In addition, the eHf(t) values of the intrusives are consistently positive (0.6–7.6), implying that they were generated by melting of an isotopically depleted mantle source, with insignificant contributions from crustal materials. The source residues likely contained 10–20% garnet and hornblende, and plagioclase was either absent or totally consumed during partial melting. Combining the regional tectonic data, we conclude that the Buqingshan paleo-ocean may have started to subduct in Middle Cambrian until Early Silurian (436 Ma), generating an important adakitic magma event during the late stage of oceanic crust subduction. Moreover, the Proto-Tethyan Ocean closed, and the Bayan Har, East Kunlun, and Qaidam blocks collided during the Middle–Late Silurian.

The tectonic setting of the West Qinling orogenic belt (QOB) during the Middle–Late Triassic remains a subject of debate. Petrogenesis of adakitic granodiorite plays a critical role in determining the nature of the lower continental crust and mantle dynamics during orogenic processes in the region. The Tadong adakitic granodiorite pluton in the western part of the West QOB is an important element of this system. Its petrogenesis can place severe constraints on the nature of the lower continental crust and mantle dynamics during the formation of the orogenic belt. U–Pb dates obtained through zircon laser-ablation inductively coupled mass spectrometry indicate that the Tadong pluton was emplaced at 220.2 ± 2.5 Ma, coeval with abundant magmatic rocks in the region. This indicates a prominent magmatic event in the western part of West Qinling during the Late Triassic. Geochemically the granodiorites are metaluminous to peraluminous high-K calc-alkalic and characterized by relatively high SiO2 (63.84–67.91 wt....

Owning to the characteristics such as high sensitivity and simplicity of apparatus, electrochemiluminescence (ECL) has become a powerful analytical technique and has been widely used. Ru(phen) 3 2+ can be intercalated into the grooves of dsDNA and act as an ECL probe efficiently, which has been applied to develop a sensitive ECL biosensor for folate receptor in this study. One ssDNA with a thiol group at its 3′ termini had been modified on the Au electrode first, and the other ssDNA with folic acid at its 3′ termini hybridized with the former one being modified on the electrode surface to form a dsDNA. In the absence of folate receptor, the 3′-terminus in the dsDNA region can be specificity hydrolyzed into mononucleotides by ExoIII and on dsDNA presents on the electrode surface, leading to the lower of ECL intensity detected. However, in the presence of the target (folate receptor), ExoIII failed to hydrolyze the dsDNA since the one 3′-terminus had been protected by the target and the other protected by the Au electrode, resulting in the enhancement of ECL intensity. The enhanced ECL intensity has a linear relationship with the logarithm of folate receptor concentration in the range of 0.66 nmol/L and 26.31 nmol/L with a detection limit of 0.1204 nmol/L. The proposed biosensor had been applied to detect HeLa cells concentration with satisfied results.

This study focuses on the zircon U–Pb geochronology and geochemistry of the Bairiqiete granodiorite intrusion (rock mass) from the Buqingshan tectonic melange belt in the southern margin of East Kunlun. The results show that the zircons are characterized by internal oscillatory zoning and high Th/U (0.14–0.80), indicative of an igneous origin. LA–ICP–MS U–Pb dating of zircons from the Bairiqiete granodiorite yielded an age of 439.0 ± 1.9 Ma (MSWD = 0.34), implying that the Bairiqiete granodiorite formed in the early Silurian. Geochemical analyses show that the rocks are medium-K calc-alkaline, relatively high in Al2O3 (14.57–18.34 wt%) and metaluminous to weakly peraluminous. Rare-earth elements have low concentrations (45.49–168.31 ppm) and incline rightward with weak negative to weak positive Eu anomalies (δ5Eu = 0.64–1.34). Trace-element geochemistry is characterized by negative anomalies of Nb, Ta, Zr, Hf and Ti and positive anomalies of Rb, Th and Ba. Moreover, the rocks have similar geochemical features with adakites. The Bairiqiete granodiorite appears to have a continental crust source and formed in a subduction-related island-arc setting. The Bairiqiete granodiorite was formed due to partial melting of the lower crust and suggests subduction in the Buqingshan area of the Proto-Tethys Ocean.

Epidermal growth factor receptor (EGFR) that has been over-expressed in many different types of cancers has become logical targets for both diagnosis and therapy. Herein, we report an electrochemical peptide-based biosensor for the detection of EGFR, in which ferrocene moiety modified peptide ligands that are specific to EGFR were immobilized on gold electrode through Au–S interaction. Upon the binding of peptide ligands with EGFR, complex formation changes occurred on the electrode surface, which resulted in current increase. The amplitude of the current increase displayed a linear relationship with logarithm of the EGFR concentrations in the range of 1.0 × 10−6–1.0 × 10−10 g L−1, with a detection limit of 3.7 × 10−11 g L−1. The proposed method has been applied for determination of EGFR in diluted human serum samples with satisfied results.

An ultrasensitive and specific electrochemiluminescence (ECL) biosensor has been designed for the p53 DNA sequence, which is based on cascade signal amplification of nicking endonuclease assisted target recycling and hyperbranched rolling circle amplification (HRCA). First of all, biotin modified hairpin capture DNA (HP) probe was immobilized on the surface of streptavidin magnespheres paramagnetic particles (PMPs). Target DNA hybridized with the loop portion of the HP probe, therefore unfolding HP to form a double-stranded DNA (dsDNA) containing the specific nicking site of the nicking endonuclease. Then, the nicking endonuclease recognized the specific nicking site and cleaved the HP into two pieces, liberating target DNA and the complementary sequence piece for the padlock probe. The intact target DNA would initiate the next cycle of hybridization and cleavage, thereby releasing multiple complementary sequences for the padlock probes. The liberated complementary sequences hybridized with the padlock probes, subsequently inducing the HRCA reaction and generating numerous dsDNA segments. Herein, Ru(phen)3(2+) was embedded into dsDNA and worked as ECL signal reporter. The reaction products were eventually pretreated by dialysis tube with the cutoff membrane to remove the residual Ru(phen)3(2+) in the solution for the following ECL measurements. Using this cascade amplification strategy, an ultrasensitive p53 DNA sequence detection method was developed with a wide linear range from 0.05 to 100 fM and a low detection limit of 0.02 fM. Moreover, this cascade amplified ECL biosensor had specific recognition capacity for noncomplementary and single- and double-base mismatched DNA. The proposed ECL biosensor might have a great potential in biomedical research and clinic analysis.

The granite of Jiaoziding dome core is located in back-Longmenshan area of the northwestern margin of Yangtze Block. The objectives of the study carried out by applying zircon SHRIMP U-Pb geochronology and geochemistry are to constrain its formation age and petrogenesis. The results show that the zircons of the samples in deformative granite and massive granite of the Jiaoziding intrusions have internal oscillatory zoning, zircons of the Jiaoziding intrusions have higher Th/U ratios (0.52–1.23, 0.32–1.16) and are igneous in origin. The results of zircon SHRIMP U-Pb dating for deformative granite and massive granite are 793 ± 11 Ma and 792 ± 11 Ma, which indicates that the granite intrusions formed in the Nanhuan of late Neoproterozoic, and formation of their time is fully consistent. The Jiaoziding intrusions are high in SiO2 (72.01%–77.65%) and Al2O3 (12.12%–14.18%) composition, and A/CNK = 0.95–1.13 (1.04 on average). It is a typical peraluminous granite, with supersaturation in Al and Si, and identified to be S-type granite. The abundance of ∑REE varies in the range of (75.81–79.97) × 10−6 (77.89 × 10−6 on average). The rocks show a LREE enrichment pattern and obvious weak to intermediate negative Eu anomalies. The trace element geochemistry is characterized evidently by negative anomaly of Ta, Nb, Ti, etc. and positive anomaly of Rb, Ba, Sr, etc. The granite emplaced by underplating of granitic magma, which formed through partial melting of sedimentary mainly of arenite, and is typical crust source petrogenesis. The Jiaoziding intrusions show postcollisional granite characteristics and regarded as postorogenic granites. Thus, the granite intrusions are interpreted as syncollisional granites resulted from the crustal thickening caused by active continental margin subduction and arc-continent collision orogeny during the Neoproterozoic in the northwestern margin of Yangtze Block. The granitic intrusion formed in a transitional environment from syncollision (compressional environment) to postcollision (extensional environment) and is the products of Rodinia supercontinent initial break-up.

The Nanyili (南一里), Laohegou (老河沟), and Shaiziyan (筛子岩) granitic intrusions are located in the southern margin of the Bikou (碧口) block in Pingwu (平武) area, Northwest Sichuan (四 川). The petrography and geochemical characteristics of the granitic intrusions as well as their source and tectonic settings are reported and discussed in this article. The Laohegou and Shaiziyan granites are with high SiO2 (69.89 wt.%–73.05 wt.%) and Al2O3 contents, and A/CNK=1.04–1.12. They are typical strongly peraluminous granites, with supersaturation in Al and Si. The abundance of ΣREE varies in the range of (33.13−89.12)×10−6. The rocks show an LREE enrichment pattern and obvious Eu negative anomaly. The trace element geochemistry is characterized evidently by a negative anomaly of Ta, Nb, Ti, etc. and a positive anomaly of Rb, Ba, Sr, etc.. Zircons of the Nanyili granite have higher Th/U ratios, and their CL images have internal oscillatory zoning, suggesting that the zircons of the samples are igneous in origin. The LA ICP-MS zircon U-Pb isotopic concordia diagram yields an age of 223.1±2.6 Ma (MSWD=1.4), which indicates that the granodiorite intrusions formed in the early Late Triassic. The Nanyili, Laohegou, and Shaiziyan granites have the characteristics of post-collisional granites and are regarded as post-orogenic granites. Thus, the granite intrusions are interpreted as syn-collisional granites that resulted from the crustal thickening caused by the collisions between the North China plate and the Yangtze plate during the Indosinian. The granitic intrusions formed in a transitional environment from syn- (compressional environment) to post-collision (extensional environment).