Abstract Occurring after the early Palaeozoic collisional orogeny and continental deep subduction, late Palaeozoic tectonic magmatism in the northern Qaidam Tectonic Belt (NQTB) related to the Palaeo-Tethys Ocean has become a critical issue. We performed a detailed geochronological and geochemical study of Lenghu (LH) granitic rocks in the western NQTB to obtain better constraints on the subduction processes of the Palaeo-Tethys Ocean in the northern Qinghai–Tibetan Plateau. LA–ICP–MS U–Pb dating of zircons from LH granitic rocks in the western NQTB yields emplacement ages of 253 ± 4 Ma and 264 ± 4 Ma, indicating a two-stage emplacement process. Geochemical analyses show that both the late Permian and Early Triassic granitic rocks have low A/CNK and A/NK values and are enriched in LILEs (Rb, Th, Ba, Zr, and Hf) and depleted in HFSEs (Sr, P, Ti, Nd, and Ta). The SREE contents range from 36 to 189 ppm, and the samples are enriched in LREEs (LREE/HREE =1.5–7.3). Values of (La/Yb)N range between 0.9 and 6.5, and all samples show negative Eu anomalies (δEu =0.2–0.6), with typical characteristics of island arc magmatism. The two-stage granitic rocks have εHf(t) values of -3.7 to +8.0 and yield a two-stage depleted mantle Hf model age of 1.51-0.78 Ga. The data suggest that the late Permian–Early Triassic granitic rocks were derived from partial melting of Proterozoic crust-related mafic to intermediate rocks with significant crust–mantle interactions. The results, combined with regional magmatic information, indicate that the South Kunlun Oceanic plate might have experienced plate rollback in the late Permian and plate retraction in the Triassic under the Kunlun–Qaidam Block.
The late Palaeozoic tectonic magmatism in the northern Qaidam tectonic belt (NQTB) related to the Palaeo-Tethys Ocean has become a critical issue.We performed a detailed geochronological and geochemical study of Lenghu (LH) granitic rocks in the western NQTB.LA-ICP-MS U-Pb dating of zircons from LH granitic rocks yields emplacement ages of 253 ± 4 Ma and 264 ± 4 Ma, indicating a two-stage emplacement process.Geochemical analyses show that the LH granitic rocks have low ACNK values and are enriched in LILEs (Rb, Th, Ba) and depleted in HFSEs (Sr, Nd, and Ta).The samples are enriched in LREEs (LREE/HREE =1.5-7.3).Values of (La/Yb) N range between 0.9 and 6.5, and all samples show negative Eu anomalies (δEu =0.2-0.6), with typical characteristics of island arc magmatism.The LH granitic rocks have εHf(t) values of -3.7 to +8.0 and yield a TCDM age of 1.51-0.78Ga.The data suggest that the LH granitic rocks were derived from partial melting of Proterozoic crust-related mafic to intermediate rocks with significant crust-mantle interactions.The results, combined with regional magmatic information, indicate that the Late Permian-early Triassic magmatism in western NQTB were controlled by subduction rollbackretraction of South Kunlun Oceanic plate under the Kunlun-Qaidam Block.
The formation and evolution of an intracontinental basin triggered via the subduction or collision of plates at continental margins can record intracontinental tectonic processes. As a typical intracontinental basin during the Jurassic, the Qaidam Basin in western China records how this extensional basin formed and evolved in response to distant subduction or collisional processes and tectonism caused by stresses transmitted from distant convergent plate margins. The Jurassic evolution of the Qaidam Basin, in terms of basin-filling architecture, sediment dispersal pattern and basin properties, remains speculative; hence, these uncertainties need to be revisited. An integrated study of the stratigraphic succession, conglomerates, U-Pb geochronology, and Hf isotopes of detrital zircons was adopted to elucidate the Jurassic evolutionary process of the Qaidam Basin. The results show that a discrete Jurassic terrestrial succession characterized by alluvial fan, braided stream, braided river delta, and lacustrine deposits developed on the western and northern margins of the Qaidam Basin. The stratigraphic succession, U-Pb age dating, and Hf isotope analysis, along with the reconstructed provenance results, suggest small-scale distribution of Lower Jurassic sediments deposited via autochthonous sedimentation on the western margin of the basin, with material mainly originating from the Altyn Tagh Range. Lower Jurassic sediments in the western segment of the northern basin were shed from the Qilian Range (especially the South Qilian) and Eastern Kunlun Range. And coeval sediments in the eastern segment of the northern basin were originated from the Quanji massif. During the Middle-Late Jurassic, the primary source areas were the Qilian Range and Eastern Kunlun Range, which fed material to the whole basin. The Jurassic sedimentary environment in the Qaidam Basin evolved from a series of small-scale, scattered, and rift-related depressions distributed on the western and northern margins during the Early Jurassic to a larger, extensive, and unified depression occupying the whole basin in the Middle Jurassic. The Altyn Tagh Range rose to a certain extent during the Early Jurassic but lacked large-scale strike-slip tectonism throughout the Jurassic. At that time, the North Qaidam tectonic belt had not yet been uplifted and did not shed material into the basin during the Jurassic. The Qaidam Basin experienced intracontinental extensional tectonism with a northeast-southwest trend throughout the Jurassic in response to far-field effects driven by the sequential northward or northeastward amalgamation of blocks to the southern margin of the Qaidam Block and successive accretion of the Qiangtang Block and Lhasa Block onto the southern Eurasian margin during the Late Triassic−Early Jurassic and Late Jurassic−Early Cretaceous, respectively.
The ductile shear deformation of Precambrian basement rocks in Wuyishan provides a crucial perspective on intraplate orogeny in the South China Block (SCB). This study focuses on the Longquan‐Badu ductile shear zone in southeastern Zhejiang, employing field observations, thin section analysis, quartz electron backscatter diffraction (EBSD), zircon U–Pb dating and 40 Ar/ 39 Ar geochronology. Two distinct phases of deformation, referred to as D1 and D2, have been identified. D1 is primarily characterized by a WNW–ESE striking foliation within a NE‐plunging lineation, indicating top‐to‐SSW shearing. The paragneiss within the Badu complex that experienced D1 deformation has been dated to 247–239 Ma through zircon U–Pb analysis, corresponding to the prevalent high‐pressure metamorphic age in the region. This correlation suggests that the D1 deformation event coincided with crustal thickening during the Early Triassic. D2 deformation exhibits folds, foliation, S‐C fabrics and mylonitic microstructures and is mainly characterized by striking NNE–SSW with steeply dip, demonstrating a dominant dextral strike–slip component. Quartz c‐axis orientations in mylonitic rocks indicate deformation temperatures between 350°C and 550°C with asymmetric girdle patterns suggesting simultaneous basal and prism slip. The plateau ages of muscovite from mylonitic rocks obtained through 40 Ar/ 39 Ar dating are approximately ~228 Ma implying that the D2 deformation occurred under retrograde amphibolite to greenschist facies metamorphic conditions during Middle Triassic. Collectively these data along with regional geological evidence signify two distinct intracontinental orogenic processes occurring in eastern SCB. Considering Early Mesozoic tectonothermal events in Cathaysia Block, it can be inferred that intraplate orogeny in Wuyishan resulted from plate‐margin collisions between SCB and peripheral plates following scissors closure of Palaeo‐Tethys from east to west.
Using orthogonalty design L9(34),the effects of plant growth regulators,AgNO3 and activated carbon etc on the induction of callus,adventition buds induction and the adventition bud rooting with Zoysia sinica Hance tender meristem were studied.The results showed that the best medium for callus inducing was MS + 0.15 mg/L NAA+1.0 mg/L 6-BA+ 27 g/L sucrose + 5.5 g/L agar,with the induction frequency of 56.8%,;the best medium for the adventitious buds induction was MS+ 0.5 mg/L 2,4-D + 1.0 mg/L CPPU +3.5 mg/L AgNO3+ 29 g/L sucrose+ 6.5 g/L agar,and differentiation rate is 68.42%,the multiplication rate was 6.3;the rooting and growing was the best on the medium 1/2MS+0.4 mg/L IBA+0.3 mg/L NAA+ 1.5 mg/L activated carbon + 25 g/L sucrose + 7.0 g/L agar.The rooting rate was 95.1%.Plant material was the best with the vermiculite + pearlite + leaf mold(1∶1∶1),and the survival rate was 99.5%.
According to the color variations of different geological bodies in the same wave band or the same geological body in different wave bands,a close geological interpretation has been made for the ETM images from the East Wenquan Basin of the east Kunlun Mountains,resulting in the establishment of interpretation makers for the Cenozoic strata and new structures.The interpretation allows us to accurately define the Cenozoic strata boundaries and Cenozoic fault locations on the ETM images.The Cenozoic strata in the mapping area can be divided into 10 mapping units based on the field survey.The Cenozoic faults include nearly NW left-lateral strike-slip faults and nearly NWW thrust nappe structures.It is believed that multispectral remote sensing image can play an important role in Cenozoic geological mapping.
Trichomonascaceae is the largest family of ascomycetous yeast in the order Saccharomycetales. In spite of the extensive body of research on Trichomonascaceae in China, there remain new species to be discovered. Here, we describe four new species isolated from several rotting wood samples from Henan Province, Central China. Phylogenetic analysis of a combined ITS and nrLSU dataset with morphological studies revealed four new species in the Trichomonascaceae: Diddensiellaluoyangensis, Sugiyamaellacylindrica, Su.robnettiae, and Zygoascusdetingensis. Clustering in the Diddensiella clade, D.luoyangensis' closest neighbour was D.transvaalensis. Meanwhile, Su.cylindrica clustered in the Sugiyamaella clade closest to Su.marilandica and Su.qingdaonensis. Also clustering in the Sugiyamaella clade, Su.robnettiae was most closely related to Su.chuxiongensis. Finally, Z.detingensis occupied a distinct and separated basal branch from the other species of the genus Zygoascus. These results indicate a high species diversity of Trichomonascaceae.
To accurately measure and evaluate reserves is critical for ensuring successful production of unconventional oil and gas. This work proposes a volumetric model to evaluate the tight sandstone gas reserves of the Permian Sulige gas field in the Ordos Basin. The reserves can be determined by four major parameters of reservoir cutoffs, net pay, gas‐bearing area and compression factor Z , which are controlled by reservoir characteristics and sedimentation. Well logging, seismic analysis, core analysis and gas testing, as well as thin section identification and SEM analysis were used to analyze the pore evolution and pore‐throat structure. The porosity and permeability cutoffs are determined by distribution function curve, empirical statistics and intersection plot. Net pay and gas‐bearing area are determined based on the cutoffs, gas testing and sand body distribution, and the compression factor Z is obtained by gas component. The results demonstrate that the reservoir in the Sulige gas field is characterized by ultralow porosity and permeability, and the cutoffs of porosity and permeability are 5% and 0.15×10 –3 μm 2 , respectively. The net pay and gas‐bearing area are mainly affected by the sedimentary facies, sand body types and distribution. The gas component is dominated by methane which accounts for more than 90%, and the compression factor Z of H8 (P 2 h 8 ) and S1 (P 1 s 1 ) are 0.98 and 0.985, respectively. The distributary channels stacked and overlapped, forming a wide and thick sand body with good developed intergranular pores and intercrystalline pores. The upper part of channel sand with good porosity and permeability can be sweet spot for gas exploration. The complete set of calculation systems proposed for tight gas reserve calculation has proved to be effective based on application and feedback. This model provides a new concept and consideration for reserve prediction and calculation in other areas.
The relatively balanced status of production process is a goal which all businesses want to achieve,but the conflicts of business operations will be covered up by the long-term relatively balanced production process and the further expansion of business scale will be restricted too.Based on the Theory of Constraints(TOC),a management mode creating production bottlenecks actively is presented to cope with systems which are relatively balanced in a long period and a fuzzy relation matrix is introduced.By applying this method to powder metallurgy parts manufacturing corporation,it is validated that the production capacity will improve in the reciprocating cycle of making and eliminating the production bottlenecks.And it is also found that the method can be applied to the operation of the whole system.
'/%3e%3cuse xlink:href='%23a' transform='rotate(23.036 .093 25.536)'/%3e%3cuse xlink:href='%23a' transform='rotate(45.87 1.273 16.18)'/%3e%3cuse xlink:href='%23a' transform='rotate(69.945 .996 12.078)'/%3e%3cuse xlink:href='%23a' transform='rotate(20.66 -19.689 31.932)'/%3e%3c/svg%3e)