730 Ma Research Articles

Neoproterozoic arc-magmatism of the Silet Terrane, Western Hoggar (Algeria), new constraints from zircon U-Pb-Hf isotope analyses and whole rock geochemistry

This study presents results of zircon U-Pb-Hf isotope analyses and whole-rock geochemistry applied to magmatic rocks of the Silet terrane in the Western Hoggar, forming a part of the Neoproterozoic arc exposed along the boundary between the LATEA metacraton and the Paleoproterozoic In Ouzzal terrane. According to zircon U-Pb geochronology four distinct pulses of Neoproterozoic granitoids magmatism are recognized in the Silet terrane: Tonian (c. 870–840 Ma), Late Tonian (c. 770 Ma), Latest Tonian (c. 730 Ma) and Late Cryogenian (c. 675 Ma).Geochemical and Hf isotope data indicate a progressive shift in geotectonic settings. The c. 870–840 Ma Tonian TTG pulses (Tonalite-Trondhjemite-Granodiorite) in the North Silet batholith, with superchondritic εHf values (+5.8 to + 7.2), suggest formation in a subduction zone. The subsequent c. 770 Ma Late Tonian magmatism, characterized by mafic compositions, reflects a back-arc tectonic setting, as evidenced by high Ti/V ratios, low V contents, and εHf values of + 6.12 to + 8.95. The c. 730 Ma Latest Tonian magmatism, with more evolved acidic pulses, indicates hybrid mantle–crustal involvement (εHf + 6.53 to + 8.08). The Late Cryogenian intrusions (c. 675 Ma), featuring the lowest εHf values (+1.84 to + 4.09) and inherited c. 870 Ma zircons, suggest formation from the melting of Tonian TTGs during continental collision.Integrating U-Pb dating with geochemical data provides a comprehensive view of the Silet terrane’s tectonic evolution, supporting a continental arc origin. Disparities in magmatism ages between the northern (c. 870–675 Ma) and southern (c. 740–640 Ma) segments of the Silet arc correlate with the diachronous collision/subduction of a V-shaped “Silet Ocean”, forming an introverted oceanic system (oceans that have formed by rifted continental blocks that were subsequently re‑joined in approximately the same position) within the broader West Gondwana context. Structural analysis indicates that the regional structures of the Silet arc were shaped in a WNW-ESE collisional transpressive regime during the Pan-African orogeny, offering new insights into the Neoproterozoic Silet arc’s geodynamic evolution and its paleogeographical location in the West Gondwana orogeny.

Nitrogen‑sulfur doped graphene-loaded SiO2/Co9S8 composites as anode materials for improved lithium storage

Heteroatom-doped graphene lamellae can effectively modulate the physical and chemical surface activities of Co9S8 materials. The addition of a second dopant atom, such as nitrogen (N) can further improve the composite properties. Herein, novel nitrogen‑sulfur double-doped graphene-loaded SiO2/Co9S8 composites (SiO2/Co9S8@NSG) were prepared by a one-step solvothermal method using polyethylene glycol as the carbon source and cobalt chloride hexahydrate as the cobalt source to yield a Deep Eutectic Solvents (DESs) system. The precursor was then obtained by adding tetraethyl silicate as the silicon source, thiourea as the sulfur source, and urea as the nitrogen source. The uniform distribution of Co9S8 in the N/S-doped graphene matrix formed graphene-coated SiO2 particles SiO2/Co9S8@NSG with high specific surface area, superior ionic conductivity, and elevated theoretical specific capacity. The N/S co-doped graphene matrix not only improved the electrical conductivity and hindered the adhesion of the particles, but also buffered the volume of the Co9S8 change and enhanced the electrochemical performance. The testing of SiO2/Co9S8@NSG composite as an anode for lithium-ion batteries (LIBs) revealed an impressive specific capacity with reversible capacity of 850 mA h/g after 900 cycles at a current density of 0.5 A/g and multiplicative capacity of 730 mA h/g at a current density of 0.1 A/g, confirming excellent cycling stability and a Coulombic efficiency close to 100 %. Overall, the proposed doping strategy looks promising for the development of high-performance LIBs.

Evidence for, and significance of, the Neoproterozoic Xuefeng Orogeny, South China

The recognition of unconformities is important for determining the long-term evolution of orogenic belts. We document an unconformity between Tonian and Cryogenian strata of the Nanhua Basin of South China. This stratigraphic break has previously been termed the Xuefeng Movement and is developed within the Yangtze Block and western Cathaysia Block. Deformation characteristics and detrital zircon U-Pb geochronology from rock units underlying and overlying the unconformity (i.e., the Niuguping and Gucheng formations, respectively) from the Anhua region of the northern Hunan Province in the southeastern Yangtze Block are documented. The Niuguping Formation displays a set of top-to-northwest imbricate thrust faults and related fault-propagation folds, NEE-plunging subparallel crenulation lineations, a foliation, and shows widespread greenschist facies metamorphism. In contrast, the overlying Gucheng Formation exhibits no obvious stratal deformation (apart from a mild inclination of bedding) and is unmetamorphosed. Detrital zircon age spectra of the samples from the Niuguping Formation are characterized by unimodal age peaks of ca. 750–730 Ma, while those of the samples from the Gucheng Formation yield a multimodal age distribution, with a few syn-sedimentary detrital zircons (<700 Ma), and much older zircons with age peaks of ca. 800 Ma, 2.1–1.9 Ga, and 2.6–2.3 Ga. Combining this data with previous geochronology indicates deposition of the Niuguping and Gucheng formations in the late Tonian (725–720 Ma) and Cryogenian (690–660 Ma), respectively. The time gap across the unconformity is some 30 Ma (720–690 Ma). The unconformity and associated structural and metamorphic break extend across the Yangtze Block and western Cathaysia Block, defining a major regional orogenic event. The significantly different detrital zircon spectra of strata across the unconformity suggest a dramatic change in the source due to the Xuefeng Orogeny in the Yangtze Block. Zircon U-Pb-Hf isotopic evidence indicates that detritus of the Niuguping Formation below the unconformity was derived from syn-depositional magmatic activity in the northern Yangtze Block, while a significant increase of Archean to Paleoproterozoic ages for the Gucheng Formation, suggests that the Xuefeng Orogeny resulted in crustal thickening and denudation in the northern Yangtze Block. These changes in provenance, along with changing deformational and metamorphic patterns, indicate evolution of the Nanhua Basin from a compressional to an extensional back-arc basin, which we infer is related to tectonic switching from an advancing to a retreating subduction system in the northern Yangtze Block at the time of the unconformity.

Fabrication of NiO-CuO/RGO Composite for Lithium Storage Property

The lithium storage performance of binary transition metal oxide/graphene composites as anode materials has been attracting more interest from researchers, based on the fact that binary transition metal oxides and graphene are expected to create a synergistic effect and exhibit improved lithium storage characteristics. In this work, a NiO-CuO/reduced graphene oxide composite (NiO-CuO/RGO) was prepared by an ultrasonic agitation process. When the NiO-CuO/RGO is applied to the anode material for lithium-ion batteries (LIBs), the batteries display high discharge capacities (at 730 mA h/g after 100 cycles at 100 mA/g), high-rate performance (311 mA h/g with 5000 mA/g), and excellent stable cyclability (375 mA h/g within 2000 mA/g after 400 cycles). Such results indicate that the combination of NiO-CuO and RGO leads to enhanced lithium storage performance, for the RGO sheets inhibit the large volume change of binary NiO-CuO and enhance the fast transport of both lithium ions and electrons during the repeated lithium cycling processes.

POMs-based metal-organic frameworks with interpenetrating structures and their carbon nanotube-coated materials for lithium-ion anode applications

The inherent characteristics of abundant, stable, and swift electron transfer make polyoxometalates (POMs) exceptionally suitable for utilization in energy storage applications, particularly in Lithium-ion batteries (LIBs). By immobilizing POMs within metal-organic frameworks, Ag-BTBA-POM was synthesized to address the challenges associated with the low electronic conductivity and solubility of POMs. To enhance the electronic conductivity of POMOFs crystals further, CNT@Ag-BTBA-POM was developed. This carbon composite material exhibits exceptional cyclic stability and electrochemical characteristics, with the discharge specific capacity stabilizing at around 730 mA h g−1 over 100 cycles.

Role of Mo thickness in growth of nanostructured MoO3 and their optical sensing properties

The main objective of the present work is to investigate the role Mo thickness in growth of nanostructured MoO3 and their application for optical sensors like photodetectors. The devices were fabricated using standard scalable microfabrication techniques. MoO3 was synthesized by Mo thin film deposition using sputtering followed by dry oxidation at 550 °C. Further, these samples were tested as photodetectors for visible regions. The test results confirm that the devices are more sensitive towards 450 nm. The photodetector made on 80 nm Mo thickness exhibited a higher responsivity of 730 mA W–1, higher detectivity of 2.47 × 1011 Jones, and higher photo to dark current ratio (PDCR) of 1.33 × 102 compared to other tested samples. Moreover, the optimized photodetector showed higher repeatability and a faster speed of 13/11 ms. These developed photodetectors could be vital for the visible light optical sensing era.

Construction of heterostructured Fe2O3/Fe7S8 hollow fibers to boost the electrochemical kinetics of lithium storage.

Heterostructured Fe2O3/Fe7S8 hollow fibers were rationally designed and synthesized via the electrospinning technique, followed by a calcination process and sulfuration treatment. Benefitting from the synergistic effect of the hollow structure and the built-in electric field induced by the heterostructure, the as-prepared Fe2O3/Fe7S8 composite anode exhibits high specific capacity (947 mA h g-1 after 100 cycles at 0.2 A g-1), excellent rate capability, and long-term cycling stability (730 mA h g-1 after 1000 cycles at 1 A g-1).

Novel solution plasma synthesis of highly durable carbon shell encapsulated platinum-based cathode catalyst for polymer electrolyte membrane fuel cells

Developing an effective method for synthesizing high-performance and durable catalysts for the oxygen reduction reaction is of great importance for cost reduction and the wide application of fuel cells. This study presents a simple and effective strategy using a plasma reaction in the liquid phase to synthesize carbon-shell-encapsulated Pt and PtFe catalysts. A carbon-shell-encapsulated PtFe catalyst alloyed with up to 29 at.% Fe exhibits a mass activity of 730 mA·mgpt−1 and a specific activity of 1772 μA cm−1, which are 2.4 and 5 times higher than that of commercial Pt/C, respectively. The carbon shell effectively maintained the low oxidation state of Pt by suppressing the formation of Pt–OH and significantly improved the durability of the catalyst in accelerated durability tests, increasing the gap in mass activity with Pt/C by a factor of up to six after 50,000 cycles. In addition, the decrease in the electrochemical surface area by the carbon shell enabled a more stable 4-electron reaction over a wide potential range. This study may provide fascinating insights into the effect of the carbon shell contributing to the improvement of the catalytic activity and durability of fuel cells as well as the novel plasma-based synthesis strategy of core-shell catalyst.

A SiO2@Al as stable and long-cycle anode for lithium-ion batteries

Silicon oxides (SiO, SiO2, SiOx, etc.) are considered as new generation of anode materials for lithium-ion batteries due to their high theoretical specific capacity and low-cost. However, the low conductivity and unsatisfied electrochemical performance have impeded their advance. In order to solve the mentioned issues, here, a porous SiO2 filled with Al anode is designed and fabricated via simple but effective melt-self-assembly method, in which, SiO2 being from the diatomite with natural porous structure. The presence of Al not only contribute certain specific capacity but also improve the conductivity of the SiO2 anodes. As expected, a high capacity of 730 mA h g−1 is obtained in the fabricated SiO2@Al electrode and the capacity retention rate reaching 95% after 312 cycles. Importantly, the rate capability is significantly enhanced delivering capacity up to 635 mA h g−1 at current density of 800 mA g−1 superior to the single SiO2 electrode. The results indicate the great potential of the fabricated SiO2@Al composite electrode as a high-performance and low-cost electrode material for the next-generation high-specific-energy lithium-ion batteries.

New evidence for the Baltican cratonic affinity and Tonian to Ediacaran tectonic evolution of West Avalonia in the Avalon Peninsula, Newfoundland, Canada

Provenance studies of quartzite clasts and enclosing sandstone units in the Avalon Peninsula, Newfoundland, Canada, were conducted to test the Baltican or Gondwanan cratonic affinities of West Avalonia and examine the stratigraphic archives of Neoproterozoic arc evolution. Four cobble-sized quartzite clasts from a syn-orogenic, Ediacaran fluvial unit mostly yield ca. 1220, 1510, and 1900–2200 Ma detrital zircon age maxima and were probably derived from sub-arc basement units. Detrital zircon U-Pb-Hf isotope statistical assessments of the clasts indicate provenance ties with Proterozoic strata of the Sarmatian craton and Timanian passive margin of northern Fennoscandia, which corroborates models for proto-Avalonia to have originated near southern or northeastern Baltica, respectively. Analogous quartzite basement units in Nova Scotia and New England also have Baltican cratonic affinities and reflect provenance from southern Fennoscandia. Ediacaran exhumation of arc and basement infrastructure was accommodated by transpressive faults during the Avalonian orogeny and resulted in the deposition of Signal Hill Group terrestrial strata. Eleven Signal Hill Group sandstone samples are correspondingly dominated by Tonian to Ediacaran detrital zircon age fractions that constrain the crustal evolution of West Avalonia. The composite dataset includes 818–777 Ma detrital zircon grains that record the rifting of a proto-Avalonia sliver or ribbon arc from Baltica. Tonian igneous rocks are rare in West Avalonia, but ca. 760 Ma and 730 Ma detrital zircon grains indicate both crust and mantle contributions to the oceanic Burin arc, its tectonic interactions with proto-Avalonia, and subsequent arc magmatism across the composite terrane. Cryogenian detrital zircon ages substantiate the timing of 700–670 Ma magmatism and 670–640 Ma tectonic interactions with Baltica or another block. The detrital zircon U-Pb-Hf isotope record of the 640–600 Ma magmatic phase includes 6–9 Myr-long, fluctuating cycles that indicate the frequency of West Avalonian arc processes in the Mirovoi Ocean prior to Avalonian orogenesis.

Early Neoproterozoic fore-arc basin strata of the Malyi Karatau Range (South Kazakhstan): Depositional ages, provenance and implications for reconstructions of Precambrian continents

Multidisciplinary geochronological, isotopic, chemical, and facial studies in the Malyi Karatau Range (MK) of South Kazakhstan elucidate the Precambrian stratigraphic framework and evolution of the Ishim Middle Tianshan microcontinent (IMT) in the western Central Asian Orogenic Belt. Detrital zircon and apatite U-Pb ages for siliciclastic rocks and chemostratigraphic Sr-C isotopic data for carbonates indicate that they deposited during 800–730 Ma. The sediments are dominated by deeper marine facies in the southwest and shallow marine facies in the northeast. According to paleocurrent indicators, the main provenance located to the west of the basin. Based on the detrital zircon age spectra, the source terrane represented a Paleoproterozoic to Archean crustal block, reworked by an early Neoproterozoic c. 850–720 Ma continental arc. Erosion of Archean and Paleoproterozoic crust is also evidenced by negative εNd values for the sandstones. The petrographic and chemical compositions of the sandstones are consistent with a continental arc source; however anomalously high concentrations of chromium in some layers point to the presence of ultramafic rocks in the source terrane. The ages of metamorphic zircons indicate a high-grade metamorphic event at provenance at c. 2.0 Ga and the ages of detrital apatites suggest a reset of U-Pb isotope system in apatite at c. 1.8–1.9 Ga. In the early Neoproterozoic, the MK located between the continental arc in the west and the oceanic basin in the east and represented a fore-arc basin. The similarity of the Precambrian magmatic and metamorphic histories and sedimentary facies indicates that the IMT, the Tarim and Yangtze cratons constituted a single Precambrian Ulutau-Tarim-Yangtze Continent (UTY). Judging from the ages of continental arcs that evolved on the northern and southern sides of the UTY, it represented an independent continent at c. 950–840 Ma and was incorporated in Rodinia at c. 830–820 Ma.

Tonian Low‐Latitude Marine Ecosystems Were Cold Before Snowball Earth

AbstractPrecambrian marine carbonate strata are commonly assumed to have formed in warm‐water carbonate factories due to the temperature dependence of non‐skeletal carbonate precipitation rates. However, some climate models and geological observations suggest that global climate was cool for tens of millions of years prior to the onset of Snowball Earth glaciation at ∼717 Ma, in conflict with common interpretations of pre‐glacial carbonates as warm‐water carbonate factories. We report the occurrence of guttulatic microfabric—a petrographic fingerprint of ikaite, a carbonate mineral that only forms in cold sedimentary environments—in the Beck Spring Dolomite, a carbonate succession deposited in a low‐latitude shallow marine environment between ∼780 and 730 Ma. This interpretation of pre‐glacial carbonate factories aligns cold conditions with vase‐shaped microfossils, possible algal fossils, and molecular clock dates for crown‐group metazoans. Our observations indicate that these marine ecosystems were able to thrive in cold low‐latitude environments millions of years before the Snowball glaciations.

Petrogenetic and tectonic implications of Neoproterozoic igneous rocks from the western Yangtze Block, South China

Spatiotemporal variations in magma sources and the petrogenetic types of igneous rocks generally record major changes in tectonic styles and crustal growth mechanisms and thus play vital roles in tectonic reconstruction. In this study, we present new petrological, geochronological, geochemical and Sr-Nd-Hf isotopic data for Neoproterozoic igneous rocks in the Western Yangtze Block (WYB), South China, aiming to constrain their petrogenesis and tectonic implications. Geochronological and geochemical data compilations indicate a prolonged (ca. 910 to 730 Ma) Andean-type magmatic arc system in the WYB; however, the initial magmatism and subsequent magmatic flare-up events in different regions of the WYB are asynchronous. Petrogenetic study reveals that most Tonian mafic rocks exhibiting typical arc-related geochemical affinities and depleted Nd-Hf isotopes are generated by the partial melting of mantle wedge that is metasomatized by subduction-related fluids and/or melts. Elemental and isotopic studies suggest that the newly identified ca. 880–851 Ma adakitic rocks in the WYB are derived from melting of thickened juvenile or ancient continental crust, while the studied A2-type and I-type granitoids originate from differentiation of mantle-derived magma or reworking of continental crust, which are the key mechanisms of crustal evolution in the WYB. This study indicates that the Yangtze Block probably lies on the periphery of the Rodinia supercontinent, and long-lived arc magmatism including mafic magma underplating and crustal reworking, and episodic magmatic flare-up that occur due to slab rollback play key roles in Neoproterozoic continental evolution of the WYB.

Reversible multi-electron redox chemistry of organic salt as anode for high-performance Li-ion/dual-ion batteries

Organic electrode materials are attracting increasing attention for rechargeable secondary batteries because of their low cost, high capacity, nontoxic and environmentally friendly. Herein, we report an excellent anode of a novel organic hexalithium salt of mellitic acid (Li6C12O12) for lithium-ion battery (LIB)/dual-ion battery (DIB). A combination of electrochemical and spectroscopic studies verifies a reversible coordination reaction mechanism based on carboxylic carbonyl and Li+ ions. Li6C12O12 delivers large reversible capacities of 730 mA h g−1 at 0.21 A/g and 372 mA h g−1 even at 2 A/g. Furthermore, the Li6C12O12 electrode enables LiFePO4//Li6C12O12 full LIB and graphite//Li6C12O12 full DIB to exhibit high capacity and good cycling stability. This work presents a new perspective on designing and tailoring organic electrode materials to build high-performance lithium-ion batteries/dual-ion batteries.

3D Hierarchical Porous Carbon Aerogel Electrocatalysts Based on Cellulose/Aramid Nanofibers and Application in High-Performance Zn–Air Batteries

Three-dimensional (3D) carbon aerogels (CAs) are composed of interconnected networks and emerge as appealing platforms for the combination of heteroatom dopants, defective sites, and hierarchical porous structures. Here, we propose an effective and sustainable strategy to construct TOCNF/ANF-Cd hydrogels/aerogels using TEMPO-oxidized cellulose nanofibers (TOCNFs), thermally stabilized aramid nanofibers (ANFs), and low-boiling-point Cd2+. Hierarchical porous N-doped aerogel catalysts (N/CA-Cd) with TOCNF/ANF synergistic cross-linking were obtained by moderate temperature pyrolysis. Apart from serving as a source of N, ANF also improves carbon retention and graphitization, increasing the electrical conductivity of carbon aerogels. Due to the spatially continuous structure and multiscale porous structure and abundant N dopants and edges/defects, the as-obtained N/CA0.5-Cd carbonaceous catalysts manifest an impressive electrocatalytic efficacy with a positive half-wave potential (0.86 V). In particular, the Zn–air batteries assembled with N/CA0.5-Cd as the air cathode catalyst have an excellent peak power density of 186 mW cm–2 and a splendid specific capacity of 730 mA h g–1.

Tracing tectonic processes from Proto- to Paleo-Tethys in the East Kunlun Orogen by detrital zircons

The East Kunlun Orogen (EKO), a crucial Tethys composite accretionary belt in the northern Tibetan Plateau, experienced a polyphase tectonic history during an orogenic evolution from the Proto-Tethys to the Paleo-Tethys oceans. It is thus an ideal natural laboratory for tracing the Tethys orogenic cycles. Although numerous studies have been done on the geologic evolution of the East Kunlun Orogen, the timing of initial subduction, final closure, and the transition from the Proto-Tethys to the Paleo-Tethys still remain controversial. This study presents U-Pb-Hf isotopic analyses of 794 detrital zircons from three modern river drainage samples and two sedimentary samples in the EKO. The analysed zircons cluster in five age groups: 2900–2100 Ma, 1900–1300 Ma, 1200–730 Ma, 550–370 Ma, and 290–200 Ma, in which almost 67 % are of Phanerozoic age. The εHf(t) values of the 550–370 Ma detrital zircons have a broad range from −28.8 to + 15.9 and exhibit a trend towards positive values, suggesting that subduction of the Proto-Tethys Ocean initiated at ca. 550 Ma and accretion of the continental arc occurred with increasing addition of mantle material. The εHf(t) values (−8 to + 13) of 290–200 Ma detrital zircons have no obvious evolutionary trend, reflecting the continuous crust-mantle interaction during the evolution of Paleo-Tethys arc. Our results, combined with previous research, reveal two discontinuous and distinct orogenic cycles from the Proto-Tethys to the Paleo-Tethys in the EKO: the Proto-Tethys orogenic cycle from oceanic subduction to continental collision and orogenic collapse at ca. 550–370 Ma, and orogenesis of the Paleo-Tethys Ocean at ca. 290–200 Ma in the EKO, with a gap of ∼ 80 Myr, during which time there was no subduction, and the extensional setting resulted in rare identifiable zircon record.

Geochronology and geochemistry of the granitoids in the Diancangshan-Ailaoshan fold belt: Implications on the Neoproterozoic subduction and crustal melting along the southwestern Yangtze Block, South China

The Neoproterozoic magmatic and tectonic history of the South China Craton (SCC) is critical for the reconstruction of Rodinia break-up and subsequent Gondwana assembly. Nonetheless, the tectonic attribution of the Neoproterozoic igneous rocks in the southwestern Yangtze is contentious, and the mechanism for crustal anatexis remains unclear. Here, we report mineralogical, whole-rock geochemical and Sr-Nd isotope data, and zircon U-Pb-Hf-O isotope data from the newly found Neoproterozoic trondhjemites and granites in the Diancangshan-Ailaoshan (DCS-ALS) fold belt along the southwestern Yangtze. Both the trondhjemites (ca. 771–762 Ma) and granites (ca. 767 Ma) have high SiO2 and low MgO contents. The trondhjemites have relatively high CaO, Na2O and Sr contents, but low K2O contents and Rb/Sr ratios, and show positive to slightly negative Eu anomalies and heavy rare earth elements (HREEs) depletions, resulting in high Sr/Y and La/Yb ratios. In contrast, the granites have lower CaO, Na2O, and Sr contents, but higher K2O and Rb/Sr, and display negative Eu anomalies and flat HREEs patterns. The trondhjemites have negative εNd(t) (-4.12 to −3.85), positive to negative εHf(t) (-2.50 to + 5.28) and low δ18O (4.37 ‰–7.27 ‰) values. In comparison, the granites have positive εNd(t) (0.09 to 0.26), εHf(t) (+1.24 to + 9.86) and higher δ18O (6.50 ‰–7.24 ‰) values. The distinct elemental and isotopic compositions between the trondhjemite and granite samples reflect two different types of crustal anataxis within different crustal levels. The trondhjemites were formed by water-fluxed melting of the juvenile mafic lower continental arc crust (with addition of ancient Yangtze basement). The granites were derived from dehydration melting of juvenile felsic middle crust. Our results imply that the trondhjemites and granites were formed in a continental arc setting. The melting processes revealed here should be applicable to decipher the widespread Neoproterozoic crustal melting along the southwestern Yangtze, which was most likely fluid-controlled via subduction-induced asthenosphere upwelling. Combined with available regional geological data, we suggest that a long-lived Neoproterozoic (∼880–730 Ma) subduction zone may have extended from the Panxi-Hanna region in the northern/western Yangtze Block to the DCS-ALS fold belt in the southwestern Yangtze. Thus, the SCC may have located on the northwestern margin of Rodinia.

A Study on the Provenance of Early to Late Triassic Clastic Rocks From the Northwestern Sichuan Basin, Southwestern China: Constraints on the Early Mesozoic Tectonic Evolution of the Western Yangtze Block

U–Pb ages of 637 new detrital zircons of Triassic sandstones from the Northwestern Sichuan Basin (NWSB), together with the petrology and paleocurrent data, are used to constrain the sediment provenance and tectonic–paleogeographic evolution of the western Yangtze Block. The U–Pb age data for the Lower Triassic detrital zircons generally show populations at ∼1,850 Ma, 980–705 Ma, 680–510 Ma, and 290–230 Ma with a minor cluster at ∼2.4 Ga. Such age spectrum features together with the eastward to northeastward paleocurrent direction implied that the Northwestern Sichuan Basin was dominantly fed by the uplifted Khamdian Paleoland. The Upper Triassic detrital zircons yield age populations at 855–730 Ma, 455–415 Ma, and 290–215 Ma and a prominent age group of 1.9–1.7 Ga. These age spectrum features together with paleocurrent data showed a provenance change with a major source of the Longmenshan thrust belt and Songpan-Ganzi terrane for the south area of NWSB and the Qinling orogenic belt for the north part of NWSB. Such transition of the provenance probably indicated the subsidence of the Khamdian Paleoland and uplift of the Songpan-Ganzi terrane and Qinling orogenic belt from the Early Triassic to the Late Triassic. This tectonic inversion most likely resulted from the gradually thermal subsidence of the Emeishan large igneous province (ELIP) and the gravitational loading triggered by the eastward shortening of the Songpan-Ganzi terrane as well as the ongoing convergence between Yangtze Block and North China Block.

Geochemistry and U-Pb-Hf zircon systematics of Cryogenian syn-rift magmatic rocks from the subsurface of the Tarim Craton: Implications for subduction-related continental rifting

Neoproterozoic rifting within the supercontinent Rodinia is generally linked to superplume activity, although the mechanisms are not well constrained at the supercontinent’s outer margins. The Tarim Craton, on the northern margin of Rodinia, is a key area for evaluating the process. We present zircon U-Pb-Hf isotopic data and whole-rock geochemistry from Neoproterozoic granitoids from drill cores in the Tarim Craton. Zircon SHRIMP geochronology yielded U-Pb ages of 744 ± 4 Ma, 750 ± 4 Ma, 755 ± 9 Ma and 734 ± 8 Ma for granitoid emplacement. The granitoids are enriched in light rare earth elements (LREE), depleted in high field strength elements (HSFE) including Nb, Ta, Sr, P and Ti, and most samples show weak negative Eu anomalies (Eu* = 0.56–1.02). Elemental data and negative zircon εHf(t) values (-18.72 to -10.23) indicate derivation from reworked continental crust. Compiled data suggest that ca. 760–730 Ma magmatism was widespread and marks the onset of extensive rifting throughout the Tarim Craton. The early Cryogenian granitoids are mainly slab failure-related and formed in a subduction-induced rift setting. Our findings consequently suggest that active continental rifting on the Tarim outer margin of Rodinia was triggered by subduction processes.

Improvement of Plasmonic CuS Nanocrystals’ Optoelectronic Properties via Cation Exchange for Infrared Detection Enhancement

Colloidal quantum dot (CQD) active thin films benefitting from plasmonic light trapping have emerged as an ideal platform to boost the performance of optoelectronic devices. Copper chalcogenides exhibit infrared absorption in concomitance with tunable localized surface plasmon resonances (LSPRs) within the near to mid infrared range. Regardless of the facile adjustment of the plasmonic oscillation and strong absorption in the infrared range, the application is limited due to very short-living photo-carriers followed by carrier recombination (∼100 ps). Herein, CuS nanocrystals (NCs) are developed as an infrared photoactive material to be functionalized via Pb2+ cation substitution. A short period of cation exchange causes a large reduction in photoluminescence, reaching efficient photo-response in near infrared as a consequence of charge separation. Estimated detectivity and responsivity as high as 2.16 × 1011 Jones and 870 mA W–1 at 750 nm illumination, respectively, were achieved. Increased reaction time and Pb2+ contents result in a growing trend in photoluminescence intensity, consistent with trap passivation: detectivity = 2.15 × 1011 Jones and responsivity = 730 mA W–1 at 950 nm illumination and 1.94 × 1011 Jones and 659 mA W–1 at 840 nm. Manipulation of optical and electrical properties of Cu2–xS NCs with precise cation substitution may open up possibilities for the application of plasmonic semiconductor NCs in optoelectronic devices.