Search

The transpressive deformation in the eastern Jiangnan Orogen during the Early Paleozoic is the structural response to the oblique convergence of the Yangtze-Cathaysia blocks, and this relationship is critical for understanding the tectonics of South China. The Jiangwan–Huangshan shear zone (JHSZ) and Baiji–Sanyang shear zone (BSSZ) exhibit NEE–SSW-trending oblique dextral and sinistral shearing, respectively, and their evolution resulted in local E–W dextral strike-slip shearing. Most kinematic vorticity values range from 0.4 to 0.81, which implies that the JHSZ and BSSZ deformed under the contribution of both pure-shear and simple-shear components, suggesting complicated deformation histories for those orogenic shear zones. The quartz and feldspar deformation mechanisms, opening angles and lattice preferred orientation (LPO) patterns of the quartz c-axis fabrics suggest shear deformation temperatures between 400 and 550 °C in the eastern Jiangnan Orogen. Locally deformation occurred under high-temperature (>600 °C) conditions. Combined with previous data and regional geology, these findings indicate that the shearing deformation in the eastern Jiangnan Orogen accommodated the oblique convergence between the Yangtze and Cathaysia blocks during the Early Paleozoic, which was possibly caused by the final assembly of Gondwana. • The eastern Jiangnan orogen experienced transpressive deformation in the Early Paleozoic. • An integrated multi-method study improves our understanding of the orogenic shear zone/transpression zone. • Early Paleozoic deformation of eastern Jiangnan Orogen is a structural response to the Yangtze-Cathaysia convergence. [ABSTRACT FROM AUTHOR]

The E-W Kanggur tectonic belt, a major tectonic belt in the Eastern Tianshan (ETS) of the Central Asian Orogenic Belt (CAOB), records the amalgamation history between the ETS and the Tarim Craton. Two generations of structural deformation (D1 and D2) are recognized by field observations in the Jingerquan, Huangshan-Jingxia, Yamansu North Mountain, and Nanbeidagou-Kanggurtag areas. Early deformation is exhibited by vertical 'A' type (asymmetrical and symmetrical) S0 folds, lenticular symmetrical boudins, S-C fabric, and nearly vertical S1 foliation, demonstrating an ~N-S compressional setting. Late deformation is characterized by ~E-W-trending dextral shearing and local S1 folding. Transpressional deformation explains the kinematic compatibility of these fold and shear structures. The new U-Pb zircon and Ar/Ar age data in this study provide constraints on the timing of deformation, suggesting that D1 occurred in the late Carboniferous-early Permian (300–286 Ma) and that dextral shearing (D2) likely occurred in the middle-late Permian (262–233 Ma). The ~N-S contraction was driven by orogenic thickening during the convergence of the North Tianshan (NTS) island arc system, the Central Tianshan (CTS), and the Tarim Craton. Dextral transpression is related to the oblique convergence between the Eastern Tianshan (ETS) and Tarim Craton. On a larger scale, dextral kinematics along the Main Tianshan Shear Zone in the Eastern and Western Tianshan, together with sinistral shearing in northeastern Kazakhstan and the Chinese Altai, accommodated the eastward escape of central orogenic materials, which were possibly affected by the convergence of the Siberian, Baltic, and Tarim Cratons. [ABSTRACT FROM AUTHOR]

The late Mesozoic tectonic domain of Southeast China transitioned from compression to extension because of the Paleo-Pacific plate rollback. However, the precise timing of the initiation of extensional tectonics remains unclear. This work focuses on the E–W-trending granite belt and the growth strata of Early Cretaceous red beds in Southeast China to establish the extensional tectonic model in Southeast China. The petrogenesis of four granitic plutons from the E–W-trending granite belt in NE Jiangxi is traced on the basis of zircon U–Pb ages and whole-rock major and trace element abundances to elucidate lithosphere evolution in the study area. U–Pb zircon dating reveals the granite emplacement at 130–135 Ma. Geochemical results demonstrate that all granite intrusions can be identified as A-type granites derived from crustal and a few mantle sources respectively through lithospheric thinning and magma upwelling under the extension background. Field observation shows the enlargement of the sedimentary area of the early Cretaceous Huizhou Formation (Fm.) in the Huangshan Basin closely after (or simultaneously) 139 Ma Shiling volcanic activities. The dip angles of the lower part of Huizhou Fm. vary from 49° to 25° towards the basin centre, and the thickness exhibited a slightly increasing trend towards the lower part within the same bed. These phenomena are consistent with the shape of the growth strata. A model, in which the NE–SW-oriented structure lines transfer to the E–W-trending tectono-magmatic belts by meeting and inheriting the previous E–W-trending tectonic axis, is established in the present work. Lithospheric thinning, magma upwelling, and crustal remelting occur within an oblique extension stress field since ca. 140 Ma. Consequently, these phenomena are influenced by the Paleo-Pacific plate rollback and the inheritance of a structural framework from the regional basement series. [ABSTRACT FROM AUTHOR]

Cretaceous syntectonic growth strata in terrigenous basins in Southeast China have scarcely been reported in previous studies. This work focusses on the growth strata of the Early Cretaceous red beds in the East Yangtze Block (EYB), especially in the Huangshan Basin in southern Anhui Province, to help determine the Late Mesozoic tectonic domain and the precise timing of the initiation of extensional tectonics in Southeast China. Field observations show that the dip angles of the red conglomerate‐bearing sandstones from the lower part of the Huizhou Fm. vary from 49° to gentle dips towards the basin centre and that the visible and estimated thickness within a single bed increases slightly downward from the upper to the lower part. These characteristics indicate that the sedimentary area of the Early Cretaceous Huizhou Formation (Fm.) has undergone an extensional process with the expansion and deepening of the sedimentary basin by rotation of the border surface (limb) and thus deposited the extension growth strata simultaneously with (or closely after) the 139 Ma Shiling volcanic activity. Caused by a NW‐SE‐oriented extensional stress field since ca. 140 Ma, a model in which NE‐SW‐oriented tectonic lines transform to E‐W‐trending tectono‐magmatic belts by intersecting and inheriting the previous E‐W‐trending tectonic fabrics is established in the present work. Consequently, these phenomena are influenced by Palaeo‐Pacific Plate rollback and the inheritance of a structural framework from the regional basement strata and deformation series. [ABSTRACT FROM AUTHOR]

In this article, an adaptive repetitive learning control (ARLC) scheme is proposed for permanent magnet synchronous motor (PMSM) servo systems with bounded nonparametric uncertainties, which are divided into two separated parts. The periodically nonparametric part is involved in an unknown desired control input, and a fully saturated repetitive learning law with a continuous switching function is developed to ensure that the estimate of the unknown desired control input is continuous and confined with a prespecified region. The nonperiodically nonparametric part is transformed into the parametric form and compensated by designing the adaptive updating laws, such that a prior knowledge on the bounds of uncertainties is not required in the controller design. With the proposed ARLC scheme, a high steady-state tracking accuracy is guaranteed, and comparative experiments are provided to demonstrate the effectiveness and superiority of the proposed method. [ABSTRACT FROM AUTHOR]

The north–north‐east‐trending (NNE) shear zones, which are defined by the Jiekou shear zone and Huangmao shear zone, are located in the eastern Jiangnan Orogen. This article provides kinematics, geochronological data, and dynamics on the Jiekou and Huangmao shear zones and serves as a reference for understanding the tectonic evolution in the South China Block during the Early Palaeozoic orogeny. All shearing signatures show that the Huangmao shear zone is dextral, and the Jiekou shear zone is sinistral. Both shear zones have certain genetic connections. The rocks from the Jiekou and Huangmao shear zones are metamorphosed and deformed into protomylonite and mylonite. Results of the deformation fabrics of feldspar and quartz and quartz c‐axis fabric analysis indicate that the ductile deformation temperatures of the Jiekou shear zone sinistral shearing are ~400–500°C. Dextral shearing with medium–high temperature (450–550°C) is mainly recorded in the Huangmao shear zone. In combination with the previous geochronology, NNE‐trending sinistral and dextral shearing in the eastern Jiangnan Orogen occurred at 465–430 Ma, coeval with the Early Palaeozoic orogeny. Therefore, the geodynamics of the NNE‐trending shear zones is related to a major strain transformation from NW to WNW, which is remotely affected by the intracontinental convergence of Yangtze and Cathaysia blocks during the Early Palaeozoic orogeny. [ABSTRACT FROM AUTHOR]

Studies on the metamorphic and related magmatic rocks within the Jiangnan Orogen, southern China, are important to understand the formation and evolution of this Neoproterozoic orogen because they can provide evidence for revealing the tectonic evolution of the South China Block. Following on from earlier attempts at stratigraphic correlation and creating a framework for the low‐grade metamorphosed basement, new first‐hand information on the composition and deformation of the East Jiangnan Orogen basement indicates that the sedimentary rocks in the north are composed of the sequential Shangxi Group (Gp) and the overlying Likou Gp, with a clear regional unconformity in between. The Likou Gp includes the Zhentou Formation (Fm.) and the Dengjia Fm., with the previously named Puling Fm. only basalt interbeds within the Dengjia Fm. The Xucun granodiorite pluton of ∼830 Ma intrudes the Shangxi Gp, thereby resulting in a 100 m‐wide hornfels zone within the wall rocks, indicating that the formation of the group occurred earlier than that of the pluton. By contrast, the southern metamorphic rocks of the Xikou Gp and the overlying Jingtan Fm. are flaky, disordered, and strongly deformed. The Jingtan Fm. is roughly equivalent to the Heshangzhen Gp and includes the Zhoujiacun conglomerates in the lower part and a rhyolite in the upper part with interbedded basalt. This assessment of Neoproterozoic stratigraphic sequences and magmatic rocks in the east of the Jiangnan Orogen differs from and rectifies previous studies, emphasizing that explanation of analytical results, particularly geochronology, should be consistent with facts gathered in the field. [ABSTRACT FROM AUTHOR]

Multi-stage Mesozoic thrust-nappe and extensional structures are distributed in the east segment of the Southeast Yangtze Block situated in the junction region of Zhejiang-Jiangxi-Anhui provinces. The features and genetic mechanism of the deformations were analyzed after a detailed field observation of their distribution, geometry, and kinematics. In addition, the time sequences of the thrust and extensional structures were determined by combining the results of the comparative analysis with the chronological evidence of strata and magmatic rocks cut by a fault or formed after a fault according to field facts. This study identified three stages of the nappe structures and at least two stages of the extensional structures during the Mesozoic. The geotectonic setting of the nappe and extensional structures was considered to be related to the different geodynamics in the study area including the Early Mesozoic geological event, i.e., N-S compression, forming Lantian fault, etc.; the Late Mesozoic flat-slab subduction, forming Xiaoxi thrust fault and tectonic window; and the roll-back of the paleo-Pacific Plate, forming extensional structures like basin marginal fault; the last compression, forming Wucheng-Shenxian fault. These findings provide additional evidence for remodeling the tectonic and geodynamic evolution of Southeast China. [ABSTRACT FROM AUTHOR]

[Display omitted] • Basalt-bearing Neoproterozoic strata in east-southern China are distributed in an arched belt. • Major elemental variations and calculated datasets indicate deep sources of basalts and are dated as 801–755 Ma. • The magmatism after 820 Ma suggests a plume origin in the four rifting basins corresponding to renewal of the Rodinia breakup. • The first stage rifting was occurred during 860–825 Ma and associated with a subduction-related extension event. The initial time (before or after ∼ 820 Ma) and geodynamic mechanism (bottom-up rising mantle plume or top-down deep subduction) of Rodinia breakup remain unresolved. This issue has impacted our current understanding of the tectonic evolution of South China. Some scholars believe that separation of the South China Craton (SCC) from the Rodinia supercontinent and contemporary SCC rifting began at ca. 860 Ma and was induced by a subduction-related extension event. In addition, other researchers consider that the SCC rifting occurred after ca. 820 Ma. We show that renewed Rodinia breakup within or along the margin of South China occurred ca. 820–740 Ma, which is supported by early studies and our newly obtained U–Pb zircon ages of 755.4 ± 1.0 and 801.6 ± 5.2 Ma from basalts and mafic intrusive bodies in an arched (arc-shaped) belt. Major elemental variations and calculated datasets for the rift-related igneous rocks suggest a mantle plume origin for the dated rocks, which indicates that the SCC rifting was driven by a rising mantle plume and formed several rifts. This arched belt, including < 820 Ma sedimentary and igneous rocks within it, may well have been the eastern part of the original Nanhua Rift, i.e., the prototype of the Nanhua Rift should be a "T" shape. Owing to a barren magmatic area at the "T" junction, the Nanhua Rift must have split into the Nanhua Rift and arched rift. We suggest that the first stage of rifting event during 860–825 Ma may occurred in the interior Yangtze or Cathaysia Block and was associated with a subduction-related extension event. [ABSTRACT FROM AUTHOR]

The widespread Late Devonian-Middle Carboniferous volcanic rocks in the Chinese Western Tianshan provide important constraints on the subduction history of the South Tianshan oceanic lithosphere. Here, we investigate the basalt, basaltic andesite, andesite, trachyandesite, and rhyolite from the Dahalajunshan Formation from Western Tianshan. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) U-Pb zircon geochronology constrains their age of formation to between 376 and 333 Ma (i.e., Late Devonian-Middle Carboniferous) with distinct variation in space (from west to east) and time (from early to late). Based on geochemical, zircon geochronological, and Sr-Nd isotopic data, we demonstrate that the Dahalajunshan volcanic was generated in a continental arc setting associated with the subduction of the south Tianshan Ocean during Late Devonian to Middle Carboniferous. The volcanic rocks belonging to Dahalajunshan Formation in the northwestern part of the Yili Block suggest that the northward subduction of the south Tianshan Ocean was initiated in the Early Devonian; those in the southern and eastern part of the Yili Block were probably produced by a northward subduction of South Tianshan Ocean during Late Devonian to Middle Carboniferous. [ABSTRACT FROM AUTHOR]

Abstract: The Caijiaping Pb–Zn deposit is a recently discovered subvolcanic hydrothermal deposit in the North Wuyi area. Its mineralization is generally distributed at the contact of rhyolite porphyry and sandstone, and in the interlayer crushed zone of Early Jurassic sandstone. Sulfide minerals in this deposit mainly consist of abundant sphalerite, galena, pyrite and chalcopyrite. Silicification, chloritization and sericitization are widely developed and closely related to the Pb–Zn mineralization. The δ34S values of early dark brown sphalerite (marmatite), main-stage sphalerite and galena (−1.1–2.5‰, average 0.83‰) suggest that the sulfur was mainly sourced from a magmatic system. Lead isotope ratios in the sulfide minerals, rhyolite porphyry and sandstone are relatively homogeneous (206Pb/204Pb=17.786–18.612, 207Pb/204Pb=15.504–15.635, 208Pb/204Pb=38.115–38.798), and are compatible with metamorphic rocks of Mesoproterozoic Zhoutan Group (Wuyi metamorphosed basement). Early Jurassic sandstone, deposited in an active continental margin or continental arc setting, exhibits low textural maturity and displays geochemical similarities to the Zhoutan Group. The rhyolite porphyry, with features of volcanic arc granite, also shows an affinity with the Zhoutan Group. SIMS zircon U–Pb dating shows that the rhyolite porphyry was emplaced at 156.0±1.2Ma, indicating that Caijiaping mineralization formed later than 156Ma. Hf isotope compositions of the rhyolite porphyry [εHf(t)=−14.3 to −8.5, average −10.6] imply that it was mainly derived from reworking of ancient crust. Potassium feldspar selected from felsic veins within the ore-cutting F4 fault yields a 40Ar/39Ar age of 120.0±4.0Ma, indicating that the Pb–Zn mineralization formed before 120Ma. Therefore, the age of mineralization is bracketed between 156 and 120Ma. Combined with regional geological information, we propose that the Caijiaping mineralization mainly formed from magmatic hydrothermal processes in a regionally extensional setting, and the Wuyi metamorphosed basement significantly contributed to diagenetic and metallogenic processes in this deposit. [Copyright &y& Elsevier]

Xiaoqinling District is an important gold-producing area in China. It ranks second to Jiaodong with regard to gold deposits. The uprising period of the Wenyu granitic pluton and the wall-rocks of the deposit, as well as the mineralizing depth and reserved place of gold ore bodies, are significant to ore exploration. Fission-track (FT) analysis of zircons and apatites of granitic rocks from the Wenyu granitic pluton shows that apatite FT (AFT) data modeling indicates a rapid cooling rate of 20°C/Ma from 138 to 120 Ma after emplacement at 138 Ma. Thermal evolution and inversion curves suggest a secondary phase of fast cooling and uprising from 45 to 35 Ma, and 35 Ma, respectively, with a cooling rate of 6.7°C/Ma and a denudation quantity of ∼4.3 km. The last cooling phase took place from <4 Ma, with an average cooling rate of ∼11.3°C/Ma and a denudation amount of 1.3 km. Total exhumation quantity of 5.6 km and uprising elevation of 7.3 km are similar to the estimated results of fluid inclusions from the Dongtongyu and Wenyu gold deposits. The 39Ar/ 40Ar dating of sericite from the fault planes of the Xunmadao-Xiaohe and Taiyao faults demonstrate two uprising activities of the ore-host metamorphic complex. The Huashan and Wenyu granitic plutons intensively occurred during 77 and 45 Ma, respectively. These data sets are valuable for understanding the uplifting process and for preserving gold ore bodies in the Xiaoqinling area, as well as for further studies on tectonic evolutions of the Taihua Complex and the Qinling-Dabie Orogen. [ABSTRACT FROM AUTHOR]

We report results of laser ablation inductively coupled plasma-mass spectrometry-based dating, as well as the analysis of bulk-rock major and trace elements, and Sr–Nd isotopes to address the genesis and tectonic settings of the Yanshanian granitoids in neighbouring sections of Zhejiang, Jiangxi, and Anhui provinces (the WZG region) within the Yangtze block. Geochronological results indicate that intense magmatic activity took place during Jurassic to Cretaceous time in the WZG region. Three episodes can be clearly distinguished by their bulk-rock geochemistry. (1) Early–Middle Jurassic granitoids (180–170 Ma) have high Sr and low Yb content, high ϵNd(t)and low initial87Sr/86Sr ratios, and weakly negative Eu anomalies. These granitoids are strongly enriched with LREE, Rb, K, and Th but are depleted of HREE, Nb, and Ta. (2) Late Jurassic to Early Cretaceous granitoids (165–140 Ma) have relatively low Sr and low Yb contents, as well as low ϵNd(t)and high initial87Sr/86Sr ratios, with characteristics similar to those of the Early–Middle Jurassic granitoids in terms of the rare earth element and trace element patterns. (3) Early Cretaceous granitoids (140–120 Ma) have extremely low Sr and high Yb concentrations, as well as high SiO2but low MgO, CaO, and Al2O3content, with strong negative anomalies in Eu, Ba, Sr, P, and Ti. These characteristics indicate that the WZG Jurassic granitoids were related to northwestward subduction of the Izanagi plate, whereas the Early Cretaceous granitoids formed in a within-plate extensional setting. The time of transition between the two tectonic environments can be constrained to ∼140 Ma. This tectonic transition may be attributed to progressive slab roll-back of the Izanagi plate. The presence of two A-type granite belts in the WZG region probably reflects lithospheric thinning. The NE trend of the A-type granite belts indicates that this extension in Southeast China was controlled by underflow of the Izanagi plate. [ABSTRACT FROM AUTHOR]

Precise age determination and source tracing of the granitic and pegmatitic gneisses of the Taihua Complex in the Xiaoqinling area are important to address the debates on the timing and processes of the amalgamation of the Western and Eastern Blocks along the Trans-North China Orogen. This paper conducted zircon dating of metamorphic rocks from the Xiaoqinling area. The results demonstrate that the collision between the Western and Eastern Blocks occurred in the Paleoproterozoic. Laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) zircon uranium–lead (U–Pb) analyses yielded consistent results. The Early Paleoproterozoic (the first period) age of 2346±28Ma was determined for granitic gneiss in the Taihua Complex and 2328±14Ma for the Xiaohe granite pluton that intruded into the granitic gneiss. The gneissose pegmatitic granite and granitic veins that intruded into the granitic gneiss yielded LA-ICP-MS zircon ages of 1881±24 and 1866±19Ma, respectively. These Paleoproterozoic ages strongly indicate that the ocean between the Eastern and Western Blocks were completely subducted at ∼1.85Ga. The ɛ Hf(t) values of the zircons from the granitic gneiss can be divided into a positive group (0.44 to 3.77) and a negative group (−3.11 to −1.27). The two-stage hafnium (Hf) model ages (T DM2(Hf)) corresponding to the positive values are between 2672 and 2887Ma. The ɛ Hf(t) values of the zircons from the Xiaohe granite range from −2.49 to 2.58, with the Hf isotope model ages ranging from 2742 to 3022Ma. Thus, the Xiaohe granite could have resulted from the partial melting of the Late Archean lower crust caused by subduction and the presence of juvenile mantle material. The primary magma of the granitic gneiss of the Paleoproterozoic Taihua Complex was derived from the differentiation of the depleted Late Archean mantle source with a small portion derived from the remelting of the subducted lower crust. [ABSTRACT FROM AUTHOR]

The dating of the uplift onset of the Huangshan pluton in the southern part of Anhui Province associated with the collision between paleo-Pacific Block and the Eurasian Block is a fundamental issue to better understand the uplift mechanisms and the regional tectonic evolution. χ values of seven zircon fission track (ZFT) samples collected from the south part of the Huangshan pluton were all <5%. Based on the grain ages of four typical ZFT samples, three thermal overprints ranging in 113-123, 72-95 and 49-66 Ma were distinguished respectively using the binomial peak-fitting method in accordance with the tectonic thermal events after south China shifted into circum-Pacific tectonic region. Apatite fission track (AFT) study of the Huangshan pluton shows ages lie between 15±3 and 56±6 Ma with all χ values >5%, and all are significantly younger than their host rock formation ages, indicating that the samples have experienced post-formation thermal history. Based on the AFT results and topography characteristics in the Huangshan pluton, three zones with different denudation intensities caused by the differential uplift of the fault blocks were recognized in this paper, indicating that denudation was driven by the increase in elevation significantly. Modeling of the AFT data shows that the earlier cooling phase took place in the early Cenozoic and involved 3.3, 3.8 and 6.0°C/Ma of cooling rates equivalent to the exhumation rates of 90, 104 and 167 m/Ma in different fault blocks. The last phase of cooling took place from ∼10 Ma with average cooling rate of ∼5.6°C/Ma, equivalent to average denudation rates of ∼156 m/Ma. The fission track results imply that the regional compression field plays an important role for the differential exhumation between individual fault blocks of the Huangshan pluton. [ABSTRACT FROM AUTHOR]

Precambrian tectonic history of Zhejiang, Fujian, and Jiangxi provinces of south China is important for understanding the tectonic evolution of South China but its magmatic activity, petrogenesis, stratigraphic sequence of the Mamianshan Group is still strongly controversial. Here we present new sensitive high resolution ion micro-probe (SHRIMP) U-Pb zircon geochronological data for the Mamianshan Group and petrographical data to constrain the tectonic framework of the regions. Our results showed that the SHRIMP U-Pb zircon age of green schists of the Dongyan Formation is 796.544.3 Ma, the Daling Formation is 756.2±7.2 Ma, and mica-quartz schist of the Longbeixi Formation is 825.5±9.8 Ma. These data indicate that the Mamianshan Group was formed not in the Mesoproterozoic, but in the Neoproterozoic and its stratigraphic sequences should be composed of Longbeixi, Dongyan, and Daling Formations from the bottom to the top. Rocks from this Group, from Zhejiang, Fujian and Jiangxi provinces, constituted the upper basement of the Cathaysia Block that overlay the lower basement of the Mayuan Group. Detailed petrographic studies demonstrate that the amphibole schists of the Dongyan Formation in the Mamianshan Group were formed within an intra-arc rift setting rather than a continental rift as previously suggested. Rather, this island-arc type formation was developed by collision and/or subduction between various blocks resulting from the breakup of the supercontinent Rodinia at c.850-750 Ma. The Zhuzhou conglomerate, distributed near Dikou Town, Jian'ou City, Fujian Province and previously considered as evidence of the Mesoproterozoic Dikou movement, is shown here not to be the basal conglomerate above the angular unconformity between the upper and lower basements. Our conclusions have important implications for understanding the Precambrian tectonics of South China. [ABSTRACT FROM AUTHOR]

This paper presents the latest progress made on the research of Mesozoic tectonic system transition from the E-W paleo-Tethyan tectonic domain into NE-NNE western Pacific domain in southeast China. Tectonism of the west Pacific domain began at middle Jurassic (J2) and formed a set of NE-trending structures, non-coaxially overprinting on E-trending tectonic belts which may be early and coevally produced by the paleo-Tethyan domain. Thus began the tectonic domain transition from the E-trending paleo-Tethyan to the NE-trending Pacific and fully finished at the early Cretaceous. The eastern Nanling area was a junction zone of the transition at middle Jurassic (J2), and ever since the junction zone might obliquely migrate to the coastal region, where is the east part of this study area. To the north of the Nanling area, the Ganjiang Fault Zone was the boundary between two tectonic domains. Corresponding to the transition of tectonic system, the geodynamics of SE China changed from a compressional system to an extensional system, which continued until the end of Mesozoic-Tertiary. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents new geological data from the Lantian area of Anhui Province, SE China, that contradict the hypothesis of the Lantian tectonic window—one of the key argument in Hsü''s Mesozoic collision tectonic model for south China. The 1:50,000-scale geological mapping of the Lantian area -located along the eastern part of the Neoproterozoic Jiangnan Belt, confirms that the Sinian–Cambrian strata unconformably overlies the Pre-Sinian formations, and that they form a syncline preserved from early Paleozoic deformation. Pre-Sinian formations (including the Banxi Group distributed in the Jiangnan Belt) do not form a Mesozoic tectonic mélange, but a normal Pre-Sinian stratigraphic sequence. The subsequent tectonic events only slightly transformed the structural framework of this area, which does not exhibit a tectonic window. Thus, these geological data call into question the model of ‘Huanan Alps’ that invokes large Mesozoic overthrust tectonics in south China. We believe that early Paleozoic tectonic activity has clearly affected the Sinian-Early Paleozoic formations in the Lantian area and given rise to the Jiangnan Belt. [Copyright &y& Elsevier]

The N55°E−trending Sanyang shear zone is located in the eastern Jiangnan orogen, and the northeastern junction between the Cathaysia and Yangtze blocks is the key to understanding the evolution of the South China Block (SCB) for early Paleozoic crustal reworking. Most shear-sense indicators (e.g., asymmetric folds, porphyroclasts, S–C fabrics, and mica fish) indicate that the Sanyang shear zone is characterized mainly by oblique sinistral shear and locally by dextral shear. Mineral deformation behavior, quartz C-axis fabrics, and the Kruhl thermometer demonstrate that shear deformation developed under high greenschist-to low amphibolite facies conditions with temperatures ranging from 450 to 550 °C. Differential stresses deduced from recrystallized quartz grain sizes were approximately 22.4–46.5 MPa, and strain rates were on the order of 10−9 to 10−10 S−1. Three dimensional (3D) strain ellipsoid measurements and the Flinn diagram of the Sanyang shear zone indicate that all samples yield oblate and flattened strain ellipsoids, which imply a contractional regime. The kinematic vorticity (Wk) 0.716–0.999, estimated by using 3D strain ellipsoid-based methods, indicates a high simple shear contribution in the shear zone. All structural, strain, and vorticity analyses suggest that the Sanyang shear zone experienced general shear with transpression. The numerical estimates allow kinematic modeling of the Sanyang shear zone, which provides important information about the structural framework for the SCB. The development of the Sanyang shear zone was a response to the oblique convergence of the Yangtze and Cathaysia blocks during the early Paleozoic orogeny. • Sanyang shear zone with sinistral shear, kinematic vorticity number from 0.719 to 0.999, and temperature conditions of 450–550 °C. • The Sanyang shear zone resulted from general shear dominated by simple shear. • 3D strain ellipsoid shape is oblate and flattened, indicating that deformation occurred under transpressional conditions. • The Sanyang shear zone developed in response to the oblique convergence of the Yangtze and Cathaysia blocks during the early Paleozoic. [ABSTRACT FROM AUTHOR]

The thrust nappe played an important role in the Mesozoic tectonic evolution of the middle part of the Central Asian Orogenic Belt (CAOB). However, the timing, structural style and kinematic processes of the thrust nappe remain controversial, particularly the detail of the thrust nappe in the Guaizihu region (110 km east of Ejinaq). In this study, we investigate new field mapping, seismic sections, geochronology and low‐temperature thermochronometric dating to provide constraints on the history of this thrust nappe in the Chaheilingashun area (northwestern Guaizihu region). The field mapping, seismic sections and structural analysis reveal that the autochthonous system had developed a series of strong fold structures in the upper Permian strata. The allochthonous system mainly contains Devonian monzogranite (U‐Pb age, ranges from 386.7 to 389.0 Ma) and Meso–Neoproterozoic schists (the maximum depositional age, ∼880 Ma), which were thrust upon the upper Permian strata during Middle to Late Triassic. Based on similar rocks, geochronological dating and the Yagan thrust, we suggest that the postulated root zone of this allochthon might have originated from the Huhetaoergai area (40–60 km northwest of the study area). The geochronological results reveal that the lower age limit of this thrust nappe is constrained by the Lower–Middle Triassic syntectonic sediments (tuffaceous sandstone, ∼247 Ma), which is the sedimentary response of the fold structure., The timing of the termination of this thrust nappe is defined by the cooling age (40Ar/39Ar data, 217–211 Ma) of the Devonian monzogranite and Meso–Neoproterozoic schists. Thus, we consider this thrust event in the study area to potentially have occurred in the period from 247 Ma to 211 Ma, which may represent the tectonic response to the closure of the Paleo‐Asian Ocean. [ABSTRACT FROM AUTHOR]

Cold stress is a significant abiotic stress that profoundly impacts the quality of fruits and vegetables. This study parsed the effects of fermentation supernatant (CFS-R1) and bacterial suspension (CRS-R1) of antagonistic bacteria R1 on the physiological quality and sugar metabolism of 'Nanguo' pears under chilling stress. The results demonstrated that both CFS-R1 and CRS-R1 significantly reduced the browning and weight loss of the fruit and suppressed the chilling injury. The relative electrolyte leakage of CFS-R1 and CRS-R1 treated fruits were reduced by 9.4 % and 9.9 % respectively on day 7 of storage, indicating improved cell membrane stability. Furthermore, both CFS-R1 and CRS-R1 maintained the sucrose content of the fruits, with CFS-R1 also increasing the content of glucose and fructose. In conclusion, the antagonist R1 can serve as a biological preservative to enhance the cold tolerance of Nanguo pear fruit by regulating sugar metabolism. [ABSTRACT FROM AUTHOR]

• New flow pattern with less downward airflow is developed and investigated. • Upper upward vortex and lower reverse-flow one for particle classification. • Upward vortex has great washing effect on fine particles at near-wall region. • Radial centrifugal sedimentation and axial washing effect are combined. • New classifier has better classification accuracy with lower energy consumption. Physical principle of conventional top-inlet classifier (CTC) with reverse-flow pattern leads to the heavily fine particles entrainment in coarse fraction. Present work concentrates on the flow-field design for less downward airflow at near-wall region of the classifier. A new middle-inlet classifier (NMC) is proposed and analyzed using computational fluid dynamics (CFD) method and powder classification experiments. The results showed that new flow pattern characterized by a pair of vortexes was created in the new classifier. The upper vortex with 80% of the total air volume moves upward and forms the washing effect at near-wall region, which effectively reduces the fine particles entrainment in coarse fraction. The downer vortex with reverse-flow pattern discharges the coarse particles timely. The radial centrifugal sedimentation combined with the axial counter-current washing effect dominates the particle classification in the NMC. Compared to the CTC, classification accuracy index of the NMC with double-vortex averagely increases by 27% with a pressure drop reduction of more than 38%. This work offers a new principle for high-efficiency particle classification and new strategy for improving the classification performance of turbo air classifiers and hydrocyclones. [ABSTRACT FROM AUTHOR]

In this study, we report U–Pb and Lu–Hf isotopic data for zircons from the Mesozoic sandstones of the Upper Yangtze area, which provide critical constraints on the provenance of these sediments and further shed light on the crustal evolution of the Upper Yangtze block. The results of isotopic chronology indicate the following: (1) The provenances of the study area are very complex, and the tectonic evolution process is relatively closed. (2) The provenances are mainly Archean–Proterozoic crystalline basement or recycled material; Paleoproterozoic crustal accretion in the western margin of the Yangtze block and Neoproterozoic magmatic activities related to subduction of the western margin of the Yangtze block; early Cambrian oceanic magmatic activity, which resulted from the intraplate extension of the northern margin of the Yangtze block; late Ordovician–early Silurian magmatic activity in the northern Yangtze block and Hercynian–Indochina uplift and erosion during the Hercynian movement. (3) The Yangtze crustal growth is episodic, and an increasing amount of ancient recycled material became part of the magmatic activity, as the zircon U–Pb ages are relatively young. [ABSTRACT FROM AUTHOR]

• Particle classification efficiency depends strongly on particle injection position. • Particle injection in strong force region truncates particle residence time. • Particle injection far away from wall reduces fines carry-over to coarse fraction. • Particle injection around peak tangential gas velocity provides efficient particle classification. This study investigates the effect of the particle injection position on particle classification performance of a cyclonic classifier. The Rankine-type vortex flow in the cyclonic classifier is divided into three characteristic regions from the wall to the center according to the tangential and axial velocity distribution. Three representative particle injection positions are selected within those regions. The particle flow and the particle residence time are investigated via the Reynolds stress and discrete phase models. The simulation result shows that particles injected in the near-wall region provide the highest separation efficiency but the lowest classification accuracy. The residence time of particles injected within the region of maximum tangential gas velocity is shorter, facilitating a rapid and efficient particle classification. The powder classification experiment result confirms the simulation result and the feasibility of this method to enhance the separation degree of particles in the vortex flow. [ABSTRACT FROM AUTHOR]

• The experimental research of gas-liquid two-phase flow was carried out. • The oscillation of gas-liquid flow will destroy the stagnant layer of wall surface. • Too high or too low WFR will both cause the poor heat transfer effect. • Oscillation frequency is the key factor of heat transfer effect. Piston cooling effect is one of the key factors affecting the reliability of internal combustion engine. In order to investigate the influence of oscillatory flow structure of engine oil in the cooling oil gallery of piston on the heat transfer enhancement, and to reveal the oscillatory heat transfer mechanism of gas-liquid two-phase flow, the oscillatory flow structure of gas-liquid two-phase flow in the simplified rectangular cavity was obtained by high-speed photography technology. The effects of oscillatory structure of two - phase flow on average heat transfer coefficient of wall surface at different oscillation frequencies and water filling ratios were analyzed, and the effects of different oscillation frequencies and water filling ratios on maximum bubble diameter and mixing ratio were also studied. Results show that oscillation frequency is the primary factor influencing the oscillatory heat transfer effect of gas-liquid two-phase flow, the higher the oscillation frequency, the higher the average heat transfer coefficient of wall surface. The average heat transfer coefficient of wall surface will decrease if the water filling ratio is extra large or small, which is the highest at water filling ratio of 40%-60%. [ABSTRACT FROM AUTHOR]

• New cyclonic classifier with middle primary and secondary tangential inlets. • Flow field characterized by two pairs of vortexes regardless of inlet air velocity. • Secondary air has great wash effect of fine particles mixed into coarse fraction. • Newton efficiency of 88% with coarse product yield of 92% was obtained. Due to the low particle classification accuracy or powder production of static air classifiers, a new cyclonic classifier with middle primary and secondary tangential inlets and feed tube was designed. The flow field and classification performance of the lab-scale classifier were investigated numerically and experimentally. The industrial cyclonic classifier's performance was also on-site tested. The simulated results show that the classifier has a main flow characterized by an upper upward vortex and a downer reverse-flow. The secondary air forms the other two vortexes with high tangential velocity near the wall and high axial velocity at the center, which helps to wash the fine particles and accelerate their discharge. The primary and secondary air occupies the separated space with a sharp dynamic boundary in the classifier regardless of inlet air velocity. The experimental lab-scale classifier has a maximum Newton efficiency of 88% with coarse product yield of 92%. The industrial classifier has been used to classify the waste microsilica for the reutilization, which well meets the industrial requirements of the classification efficiency and energy consumption. [ABSTRACT FROM AUTHOR]

The Mesozoic to Cenozoic mountain uplift, exhumation, and deformation of the SW Tianshan Mountains (Kyrgyzstan and Northwest China) offer an important window to understand the intra-continental rejuvenation mechanism of the Central Asian Orogenic Belt (CAOB), as response to the far-field effects of the India-Asia collision. This article presents new observation and data for the planation surface and sedimentation and deformation features of the regional intermountain basins to rebuild the orogenic history in Mesozoic to Cenozoic. Three planation surfaces were recognized by field observation, showing that the mountain may have experienced lengthy erosion since the end Cretaceous, and a continuous planation surface may have formed at the Eocene to Oligocene. The filling sequences and deformation character revealed that the orogenic disintegrate and intermountain basin formation likely began in the end of Oligocene. Subsequently, the uniform planation surface in Western Tianshan may have begun to disintegrate, leading to the basin-and-range landform formation. Folds and nappes in the Cenozoic basins, large-scale thrusting of Palaeozoic rocks over Cenozoic sediments at the basin margin associated with the rapid mountain uplift may have occurred at the end of Early Pleistocene, suggesting a tectonic inversion. The Mesozoic-Cenozoic Tianshan uplift and deformation were likely induced by the collision/accretion along the southern margin of Eurasia. Both the northward propagation of the Parmir syntaxis to the SW Tianshan and the oblique dextral faulting of the Talas-Fergana fault have likely played an important role on the formation and deformation of the Cenozoic basins in the SW Tianshan. [ABSTRACT FROM AUTHOR]

• Source region of the Ordovician sandstones suffered stronger weathering than that of the Cambrian sandstones. • Baoshan block was located at Indian margin of East Gondwana in the early Paleozoic. • Subduction initiation of the Proto-Tethys Ocean was at 540-500 Ma. • A shift in the tectonic setting occurred at East Gondwana margin. • Subduction of the Proto-Tethys Ocean and formation of the peripheral orogens provided the driver for ecological evolution. The effect of plate interactions on surface processes, environmental changes of the earth and their contributions to biodiversification during Gondwana assembly has been hotly debated in the last decades. The late Neoproterozoic-early Paleozoic was a key period in the tectonic assembly of Gondwana, global climate change and metazoan evolution. During this interval, the amalgamation of Greater Gondwana was succeeded by the subduction initiation of oceanic slabs in the Proto-Tethys Ocean. Here, we use whole-rock geochemical data, detrital zircon U-Pb and Hf isotopic of Cambrian and Ordovician sedimentary rocks from the Baoshan block in the Southeastern Tibetan Plateau combined with existing data in the literature to constrain the timing of subduction initiation of the Proto-Tethys Ocean at 540-500 Ma. The results show that the Baoshan block, adjacent to the Pinjarra Orogen on the northern margin of India, witnessed the transition from passive to active continental margin in East Gondwana. After the subduction initiation, the source of the sedimentary rocks experienced more intense weathering, causing a higher sediment flux. Contemporaneously, the Cambrian Explosion and stepwise increase in atmospheric oxygen accompanied the Greater Gondwana assembly at the late Neoproterozoic-early Paleozoic boundary. Subduction of the Proto-Tethys Ocean and occurrence of peripheral orogens further increased atmospheric O 2 content, transported nutrients to the ocean and reduced the greenhouse effect, which provided major propulsion for biological evolution. [ABSTRACT FROM AUTHOR]

Large-scale volcanism in the late Mesozoic was a prominent geological event in southeast China. The late Mesozoic volcanic sequences, named the Moshishan Group, are exposed in Zhejiang Province and are predominantly felsic in composition with subordinate mafic magma and rare andesites. To understand the late Mesozoic tectonic evolution of southeast China, we present zircon U–Pb dating, major and trace element analyses, and Hf isotopic compositions from felsic volcanic rocks of the Moshishan Group. Zircon U–Pb dating shows that the Moshishan Group formed between 145 and 129 Ma. The εHf(t) of the analysed zircons ranges from −16.58 to +6.89, and theTDM2age ranges from 753 to 2238 Ma with a major peak at ca. 1870 Ma. Hf isotopic compositions of zircons in Early Cretaceous volcanic rocks are more radiogenic than that of the metamorphic basement rocks, indicating a juvenile component in these magmas. Major element concentrations show that the volcanic rocks mainly belong to the high-K calc-alkaline series. Both zircon saturation temperatures and the εHf(t) values of zircons gradually increased with the evolution of the magma. Trace element data indicates that neither magmatic differentiation of mantle-derived magma nor mixing of magmas from different sources were the predominant magmagenetic processes. Earlier studies suggest that contemporaneous underplating contributed to the heat source that induced crustal melting and to the material origin that inconsistently mixed with the local crustal melts. Magmatic underplating is likely to have occurred because of the southwestward subduction of the Pacific plate with episodic slab rollback. The data obtained in this study suggest that the crust–mantle interaction under the influence of slab rollback played a progressive role in the formation of Early Cretaceous felsic volcanic rocks in southeast China. [ABSTRACT FROM AUTHOR]

Northwestern Fujian contains abundant well-studied Precambrian basement, and was a composite terrane in Cathaysia during the Neoproterozoic; however, its magmatic activity, petrogenesis, and tectonic evolution remain controversial. This article focuses on the geochronology and geochemistry of the Neoproterozoic Group in order to resolve the above problems. We provide new SHRIMP U-Pb zircon dating for the Mamianshan Group: 851.9 ± 9.2 to 825.5 ± 9.8 Ma for the Longbeixi Formation, 796.5 ± 9.3 Ma for the Dongyan Formation, and 756.2 ± 7.2 Ma for the Daling Formation. These ages document the existence of Neoproterozoic magmatism in the northwestern Cathaysia Block. Dongyan Nd-Sr isotopic data show that mafic amphibolite schists, mafic greenschists, and quartzofeldspathic schists were derived from a more depleted mantle (initial εNd˜ +5.5 and87Sr/86Sr ratio 0.703409643), a mixture of depleted mantle and crustal components (initial εNd˜ −1 and87Sr/86Sr ratio 0.702045282–0.704147714), and late Palaeoproterozoic continental crustal materials (initial εNd< −1 and87Sr/86Sr ratio 0.71083603), respectively. These new data, together with previous studies, suggest a bi-subduction-collision orogenic model for the Neoproterozoic evolution of the Yangtze and Cathaysia blocks. Our plate tectonic scenario involves earlier NW-dipping subduction during 1.0 Ga–860 Ma along the southeastern margin of the Yangtze Block and later NW-dipping subduction near the northwestern margin of the Cathaysia Block starting at ca. 850 Ma. The 796.5 ± 9.3 Ma age of the volcanic Dongyan Formation suggests that the final assembly of the Yangtze and Cathaysia blocks probably occurred after ca. 800 Ma. The 756.2 ± 7.2 Ma age of the Daling Formation indicates that post-orogenic extensional magmatism took place after 800 Ma along the northwestern margin of Cathaysia. [ABSTRACT FROM AUTHOR]

The force that drives continental drift has been one of the most challenging subjects of the plate tectonics theory in the last decades. The Proto-Tethys evolution exemplifies a scenario of drifting of continental plates during closure of the Proto-Tethys Ocean. The Pan-Cathaysian blocks in the Southeast Asian tectonic realm (SATR) derived from break-up of the Rodinia supercontinent witnessed the entire process of the Proto-Tethys evolution. The blocks and suture zones between them offer crucial information on the dynamics of continental drifting linked to shallow mantle convection and deep mantle flow. Break-up of the Pan-Cathaysian blocks from the Rodinia and opening of the Proto-Tethys Ocean, e.g., the Changning-Menglian (CM) Ocean and the Tam Ky-Phuoc Son-Po Ko (TPP) Ocean, is evidenced by the volcano-sedimentary records in the SATR and their source affinities. Subsequent convergent tectonics occurred during the subduction of the Proto-Tethys CM oceanic plate beneath the northern margin of the Gondwana and of the oceanic plate of the TPP subsidiary ocean beneath the Truong Son and Kontum blocks. Occurrence of tectonic mélanges, e.g., the Lancang mélange, and extensive arc (continental or intra-oceanic) magmatic rocks attests the switch from passive to active plate margins, forming advancing subduction zones (Andean-type) along both the distal and proximal margins of the CM Ocean, and within the TPP Ocean. Jinshajiang-Ailao Shan-Song Ma (JAS) rifting proceeded and Dapingzhang back-arc rifting occurred during or subsequent to the transition from advancing to retreating subduction along the southern margin of the Indochina block. Closing of the CM and TPP oceans in the SATR by suturing of the oceans and collision of the continental blocks occurred in the late early Paleozoic, which is evidenced by, e.g., existence of high-pressure rocks along the CM suture and post-collisional magmatic rocks along the TPP suture zone. The Proto-Tethys evolution in the SATR narrates a scenario of supercontinent break-up and assembly through continental drifting. Progressive Gondwana-centered convergent drifting of the Pan-Cathaysian blocks induced progressive closure of the Proto-Tethys main and subsidiary oceans, and rifting and closing of the rift basin and back-arc basin. Advancing subduction-ridge spreading-retreating subduction systems (ARRs) or subduction-spreading-subduction systems (SSSs) were formed and transported toward the Gondwana during the convergent drifting of the continental blocks. It is suggested that coupled shallow- and deep mantle flow, i.e., stratified mantle convection, is the major driving mechanism of the Gondwana-centered convergence of the Pan-Cathaysian blocks. In the model, the shallow-mantle convections directly control the subduction geometries and plate kinematics, while the deep-mantle convection is responsible for the drifting of the continental blocks, formation and migration of the SSSs and ARRs. [Display omitted] • The Pan-Cathaysian blocks witnessed the entire Proto-Tethys evolution. • The Proto-Tethys evolution narrates a cycle of supercontinent break-up and assembly. • Pacific-type continental margins occurred during closure of the Proto-Tethys ocean. • ARRs or SSSs formed and transported toward the Gondwana during closure of the Tethys ocean. • Stratified mantle convection as the driving mechanism of closure of the Tethys ocean. [ABSTRACT FROM AUTHOR]