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The moisture and thermal characteristics of expansive soil slopes have a significant impact on the strength and overall stability of the soil. In this study, the medium-strength expansive soil vegetated slope in Baise, Guangxi, was taken as the research object. Through the combination of numerical simulation and measured meteorological data, the impact of moisture and heat characteristics on slope stability was then analyzed, and optimal geometric parameters conducive to the stability of vegetated slopes were proposed based on these findings. The research results indicate that under long-term climatic conditions, solar net radiation has the most sensitive effect on the evaporation of slope soil. During the evaporation process, vegetation transpiration dominates in the vegetation-covered layer, while below the depth of the vegetation cover layer, soil evaporation itself plays a dominant role. Under the conditions of evaporation-rainfall-evaporation, slopes with a smaller permeability coefficient in the vegetation cover layer have significantly higher safety factors than slopes with a larger permeability coefficient and bare slopes. A steep vegetated slope with a slope gradient of 50° can maintain slope stability with proper handling of its height. The research findings have reference value for the design and construction of vegetated slopes with expansive soil. [ABSTRACT FROM AUTHOR]

Systematical analyses of data from GEOROC and PetDB database show that large amount of Cenozoic andesites occurred in the various oceanic environments such as mid-oceanic ridge, plume-related island and oceanic arc. In this study, we employed the geochemical data of 351 mid-ocean ridge andesites (MORA), 2 539 plume-related andesites (PRA) and 3 488 oceanic arc andesites (OAA) from the database to discuss the relationship between andesite tectonic settings and their geochemical features, thereby making an attempt to construct tectonic discrimination diagrams. Based on the data-driven pattern, all available elements were employed to derive logratios for the possible coordinates, and the overlap-rate calculation was adopted to evaluate the discrimination effect of more than 330 000 prospective diagrams. Finally, four tectonic discrimination diagrams have been successfully established to identify MORA, PRA and OAA, which can be utilized to identify the original settings of andesite with an age range from Cenozoic to Archean a certain extent. Of these diagrams, PRA is mainly distinguished by high LREE/HREE ratio due to enriched mantle source. Whereas, OAA is mainly characterized by high LILE/HFSE ratio, which reveals that fluids derived from subducted slab play an important role in forming oceanic arc andesites. Consequently, the petrogenesis of andesites is closely related to their tectonic settings. However, it should be noted that those andesites formed in both continental and oceanic environments cannot be effectively distinguished using these diagrams. We strongly recommend integrating the discrimination diagrams result with other geological information to reach a comprehensive interpretation of evolution history with those ancient andesites. This paper presents a case study which suggests that data-driven method is a powerful tool for solving geological problems in this 'big data" era. [ABSTRACT FROM AUTHOR]

SiO2 aerogel @ carbon nanotube anchored on graphene sheet (SiO2/CNT/GE) has been produced by a mechanical mixing method. The SiO2 nanoparticle and carbon nanotube are dispersed on graphene sheet. When the current density of the SiO2/CNT/GE material is 120 mA g−1 for lithium ion semi-battery, the first discharge and charge capacities are 839.3 mA h g−1 and 303.5 mA h g−1, respectively. After 200 cycles, its discharge capacity retains 624.3 mA h g−1. When the SiO2/CNT/GE material is used as a negative electrode and LiMn2O4 as a positive electrode for a full cell, the first discharge capacity is 732 mA h g−1, and the first coulomb efficiency is 93.18%. After 200 cycles, the discharge capacity can still be maintained at 217.9 mA h g−1, indicating its potential as a negative electrode material for lithium ion battery. [ABSTRACT FROM AUTHOR]

Pore structure characteristics of ultra-low permeability reservoirs are studied in this paper. The impact of pore structure characteristics on permeability and reservoir development effect is analyzed by conventional and constant-rate mercury penetration experiments. The results show that the frequency curve of pore radius distribution of ultra-low permeability reservoirs has little change with permeability. The average pore radius in ultra-low permeability reservoirs with different permeability levels had little difference, and its distribution ranges from 98.5 to 110.1 μm. With decrease of permeability, the frequency distribution curves of throat radius and pore-throat ratio change significantly. The peak value of throat radius curve moves to the left and increases significantly, and the average throat-radius distribution decreases from 2.33 to 0.91 μm. However, the impact of pore-throat ratio on permeability is contrary to that of throat radius. Both throat radius and pore-throat ratio has strong correlation with permeability, and they are in exponential relationship. With the in-depth study, it is found that seepage capacity of reservoirs is restricted mainly by throat radius and pore-throat ratio. When throat radius decreases to less than 1 μm and pore-throat ratio increases more than 130, permeability decreases sharply and obviously. When permeability is less than 2 × 10−3μm2, the proportion of fine throats and medium throats under the condition of effective water injection is significantly lower, and the production of single well and the recovery efficiency by water flooding in ultra-low permeability reservoirs are low. The study explains effectively the fundamental reason for the poor efficiency of production and recovery of ultra-low permeability reservoirs from the mechanism. [ABSTRACT FROM AUTHOR]

A waste corn cob core-derived SiO2 @ graphene-like carbon nanocomposite (CCC) has been synthesized by a hydro-thermal and high-temperature carbonization process. The CCC material is carbonized at 900 °C (CCC-900). The SiO2 nanoparticle with a granule size of 100–200 nm could be grown on the graphene-like carbon nanosheets. The BET-specific surface area can be calculated to be 481.81 m2 g−1. When it is used as an anode material for lithium-ion battery, the CCC composite can display the foremost discharge capacity of 2051.5 mAh g−1 at 200 mA g−1 and the maintain capacity of 125 mAh g−1 after 200 cycles. The high foremost discharge capacity could be attributed to the synergistic effect of SiO2 nanoparticles and graphene-like sheets. [ABSTRACT FROM AUTHOR]

The development of a novel signal amplification system is described for sensitive determination of α2,6-sialylated glycans (α2,6-sial-Gs), an important prognostic tumor biomarker. First, Fe-based metal-organic frameworks (Fe-MOFs) with silver nanoparticles (AgNPs) decorated onto the outer surface were designed and synthesized with controlled octahedron structures. The new Ag/Fe-MOFs nanocomposite possessed strong conductivity and a large surface area to carry more nanoprobes. To connect the Ag/Fe-MOFs nanocomposite with more groups, the nanocomposite was functionalized by -COOH with SH-PEG-COOH to bind with an α2,6-sial-Gs catcher, M-APBA, via -CONH- bonds. More importantly, the Ag/Fe-MOFs also exhibited an excellent endogenous redox mediator property to produce electrons, which is the fundamental mechanism underlying amplification of an electronic signal. A gold electrode was used to accelerate electron transfer and immobilize the α2,6-sial-Gs lectin (SNA). After the sandwich-type catcher recognition (SNA/α2,6-sial-Gs/M-APBA), the current peak response was provoked in the process of oxidizing AgNPs to Ag+ in the forward anodic potential sweep, while Cl− in a PBS solution was transferred into Ag+ to maintain charge neutrality. Optimized particles were employed for direct fabrication of the sandwich-type affinity biosensor, which was found to show a linear detection range from 1 fg mL−1 to 1 ng mL−1 with a detection limit of 0.09 fg mL−1. Furthermore, the biosensor exhibited excellent specificity and stability, indicating that such a novel nanobiotechnology platform can be used to initiate potential utility for monitoring biomarkers in serum. [ABSTRACT FROM AUTHOR]

A simple colloidal crystal template method was used to prepare Sn/TiO2/graphite carbon microsphere composites (xSn/TiO2/GCM, x = 2.0, 1.0, 0.2, 0.5) with porous layers. Then, the composites were represented using X-ray diffraction, energy dispersive spectrometry, scanning electron microscopy, transmission electron microscopy, and nitrogen physical adsorption/desorption. Meanwhile, the photocatalytic activities in CO2 reduction were studied under simulation of visible light exposure. It was confirmed that the Sn/TiO2/GCM composites had layered porosity, graphitized carbon matrix, and high metal compound content, and their morphology was greatly affected by the acetone amount. The outputs of CO and CH4 coming into the photocatalytic CO2 reduction reaction of Sn/TiO2/GCM were 619.46 and 14.46 μmol g−1, respectively. Among the two products, the highest production rate observed in 0.5Sn/TiO2/GCM. Because of these factors, the layered porous Sn/TiO2/GCM composites have good photocatalytic performance under simulated visible light irradiation and have unique composition and structure characteristics, which give broad application prospects in electrode materials, catalysts, and adsorbents. [ABSTRACT FROM AUTHOR]

Alkali–surfactant–polymer (ASP)-produced effluent contains polymer, alkali and surfactant, and it has higher content of suspended oil droplets and suspended solids than ordinary effluent. To decrease environmental pollution caused by the discharge of produced effluent, the feasibility of re-injecting a new ASP flooding system prepared with ASP-produced effluent was studied and discussed in this paper. The results of the experiments reveal that three main factors affect the performance of the new ASP system: the polymer concentration, the suspended oil droplet and suspended solids content and the salinity of the ASP-produced effluent. It is recommended that the average content of suspended oil droplets and suspended solids does not exceed 500 mg/l and that the salinity does not exceed 8000 mg/l when the produced effluent is introduced into a new ASP system. Subsequently, a laboratory displacement experiment on ASP flooding was performed. The experimental results reveal that the oil recovery of the new ASP flooding system was improved by 20.38%, and the ultimate oil recovery was 65.46%, which is 0.65% higher than that of an ASP flooding system prepared with ordinary effluent. ASP-produced effluent and ordinary effluent achieve nearly the same oil recovery. However, ASP-produced effluent is more environmentally friendly. An oil displacement test of ASP flooding with a new ASP flooding system was conducted in block A of W oil field, and good development results were achieved: The 25 production wells in the pilot test area were all effectively improved, with the minimum water cut reduced by 14.40% and the average daily oil production increased by 51.28 tons. [ABSTRACT FROM AUTHOR]

The waste buttonwoods, pineapple peels, and lettuce leaves have been activated by KOH and carbonized through a high-temperature process. When used as the anode materials for lithium-ion battery, the activated buttonwoods (BWs), pineapple peels (PPs), and lettuce leaves (LLs) can display that the first discharge capacities of BWs, PPs, and LLs are 313.9 mAh g−1, 296.6 mAh g−1, and 674.5 mAh g−1 and those of charge are 162.2 mAh g−1, 129.0 mAh g−1 and 357.2 mAh g−1, respectively. After 200 cycles, their discharge capacities are 164.8 mAh g−1, 96.1 mAh g−1, and 209.6 mAh g−1, respectively. In addition, the energy density of LLs is the highest among the three materials, while its capacity retention ratios are lower than those of BWs. It could be due to the high Si content of LLs, a honeycomb-like porous structure of BWs and high-specific surface area of BWs and LLs. [ABSTRACT FROM AUTHOR]

In 2011, Chris Peikert and Brent Waters proposed the concept of lossy trapdoor functions, which is an inherent and powerful cryptographic concept. Lossy trapdoor functions can be used for simple black-box constructing CCA encryption schemes, collision-resistent hash functions and oblivious transfer schemes. Chris Peikert and Brent Waters constructed lossy trapdoor functions based on decisional Diffie–Hellman assumption and learning with errors problem separately, which can be generalized to all-but-one trapdoor functions. In this paper, we generalize the lossy trapdoor functions and all-but-one trapdoor functions based on the polynomial ring separately, and we construct two types of trapdoor functions based on polynomial learning with errors assumption, which have more throughput and efficiency. [ABSTRACT FROM AUTHOR]

The "strong trapdoor function for lattice" has been constructed by Daniele Micciancio and Chris Peikert in EUROCRYPT 2012, which is simple, efficient, and easy to implement. In this paper, we present a new trapdoor function based on "ring learning with errors" problem (Ring-LWE) on lattice, and simultaneously the corresponding efficient inverse algorithm is given which involves two sub-algorithms: the trapdoor inverse algorithm and the iterative inverse algorithm. Our trapdoor function for lattice based on Ring-LWE is simultaneously more simple and efficient because of the ring structure. In addition to these advantages, our algorithm extends the parameters, and this can make our trapdoor function have a wider choice of applications. [ABSTRACT FROM AUTHOR]

The study of basement geochronology provides crucial insights into the tectonic evolution of oceans. However, early studies on the basement of the Xisha Uplift were constrained by limited geophysical and seismic data; Xiyong1 was the only commercial borehole drilled during the 1970s because of the huge thickness of overlying Cenozoic strata on the continental margin. Utilizing two newly-acquired basement samples from borehole XK1, we present petrological analysis and zircon uranium (U)-lead (Pb) isotope dating data in this paper that enhance our understanding of the formation and tectonic features of the Xisha Uplift basement. Results indicate that this basement is composed of Late Jurassic amphibole plagiogneisses that have an average zircon Pb/U age of 152.9±1.7 Ma. However, the youngest age of these rocks, 137±1 Ma, also suggests that metamorphism termination within the Xisha basement occurred by the Early Cretaceous. These metamorphic rocks have adamellites underneath them which were formed by magmatic intrusions during the late stage of the Early Cretaceous (107.8±3.6 Ma). Thus, in contrast to the Precambrian age (bulk rubidium (Rb)-strontium (Sr) analysis, 627 Ma) suggested by previous work on the nearby Xiyong1 borehole, zircons from XK1 are likely the product of Late Mesozoic igneous activity. Late Jurassic-Early Cretaceous regional metamorphism and granitic intrusions are not confined to Xisha; rocks have also been documented from areas including the Pearl River Mouth Basin and the Nansha Islands (Spratly Islands) and thus are likely closely related to large-scale and long-lasting subduction of the paleo-Pacific plate underneath the continental margins of East Asia, perhaps the result of closure of the Meso-Tethys in the South China Sea (SCS). Controversies remain as to whether, or not, the SCS region developed initially on a uniform Precambrian-aged metamorphic crystalline basement. It is clear, however, that by this time both Mesozoic compressive subduction and Cenozoic rifting and extension had significantly modified the original basement of the SCS region. [ABSTRACT FROM AUTHOR]

The Qinling orogen is a typical composite orogen for understanding multi-stages of magmatism and orogenic processes. Many studies have been carried out on the magmatic rocks in the Qinling orogen but their petrogenesis is still controversial. This paper presents a review of all granitoid rocks based on previous and new studies of geochronology and geochemistry. Four distinct periods of granitoid magmatism, Neoproterozoic (979-711 Ma), Paleozoic (507-400 Ma), Early Mesozoic (250-185 Ma) and Late Mesozoic (160-100 Ma), have been recognized from the Qinling orogen according to zircon U-Pb ages, intrusion associations and deformation, as well as regional geology. The Neoproterozoic granitic rocks consist of three stages at 979-911, 894-815 and 759-711 Ma, respectively, corresponding to strongly deformed S-type, weakly deformed I-type and A-type granitoids. They can be interpreted as magmatic occurrences in syn-collisional, post-collisional and extensional settings, respectively, in response to old continental terranes of the Neoproterozoic tectonomagmatic events in the old continents of China, such as South China and Tarim cratons. Although this continental terrane would be involved in the Phanerozoic Qinling orogeny, the Neoproterozoic magmatic rocks are not the products of the Qinling orogenic processes. The Paleozoic magmatic rocks can be classified into three stages at 507-470, 460-422 and 415-400 Ma, respectively. The first-stage magmatism is temporally associated with ultra-high pressure metamorphism in the North Qinling terrane. These magmatic rocks are interpreted as magmatic occurrences in subductional, syn-collisional and post-collisional settings, respectively. The Early Mesozoic magmatic rocks occur in two stages at 252-185 and 225-200 Ma, respectively. The first-stage granitoids are mainly represented by I-type quartz diorites and granodiorites, and the second stage by granodiorites and monzogranites with the I-to A-type characteristics and some with rapakivi textures. Their emplacement ages and geochemical parameters such as A/CNK, KO/NaO ratios and εNd( t) values do not show any polarity change in perpendicular to subduction/collision zone. Therefore, all these Early Mesozoic granitoids are unlikely the product of continental subduction as some researchers suggested. Instead, they are plausibly related to the subduction of the Mianlue Ocean and the subsequent collision between the South China Craton and the South Qinling terrane. The Late Mesozoic granitoids were emplaced mainly at two stages of 160-130 and 120-100 Ma, and characterized by the evolution from I- to I-A- and A-type granitoids. These characteristics are consistent with the granitoid magmatic evolution from contractional to extensional settings during the Jurassic/Cretaceous in eastern China. Accordingly, the Late Mesozoic granitoid rocks in the Qinling orogen probably have a similar petrogenetic mechanism to those of the huge magmatic belt along the western Pacific margin, i.e., intra-continent magmatism related to a far-field effect of the subduction of Paleo-Pacific plate. [ABSTRACT FROM AUTHOR]

Pelitic granulite from the Khondalite Belt, North China Craton, is composed of garnet, sillimanite, perthite, biotite and quartz. Oriented rutile needles in garnet are reported for the first time from the granulite. The rutile needles have been identified by optical microscopy and confirmed by in situ Raman spectroscopy, where they show the characteristic bands at 446-448 and 610 cm. Because of their very strong shape preferred orientation in 3-4 easily observable directions, these rutile needles are interpreted to have formed by precipitation during exhumation and cooling following peak metamorphism. The ternary feldspar geothermometer gives a peak metamorphic temperature of ~ 980 °C at 10 kbar. The presence of oriented rutile needles in garnet is suggested to be a valuable indicator of ultrahigh-temperature (UHT) metamorphism in the Khondalite Belt and therefore likely in other UHT terrains. [ABSTRACT FROM AUTHOR]

Zircon U-Pb dating of early Paleozoic granitoids in North Qinling yields three age peaks of ∼500, ∼452 and ∼420 Ma. They can be temporally correlated with high-pressure to ultrahigh-pressure metamorphism at ca. 500 Ma, retrograde granulite-facies metamorphisms at ca. 450 Ma and amphibolite-facies metamorphism at ca. 420 Ma, respectively. The first episode of granitic magmatism is considered to have resulted from continental collision, whereas the second and third episodes of magmatism are attributed to crustal uplifting. Combined with the regional geological setting and new results from high-pressure and ultrahigh-pressure metamorphic rocks, the ca. 500 Ma magmatism is interpreted as the result of partial melting of sedimentary rocks in accretionary wedge between the south Qinling microcontinent and the north Qinling belt including the southern margin of the North China Craton. The ca. 450 Ma intensive magmatism is ascribed to dehydration melting of deeply subducted continental crust at thickened conditions in response to slab breakoff, and the final magmatism in ca. 420 Ma is interpreted as the product of partial melting during the tectonic transition from contraction to extension. [ABSTRACT FROM AUTHOR]

Any linear code can be used to construct a linear secret sharing scheme. In this paper, it is shown how to decide optimal linear codes (i.e., with the biggest information rate) realizing a given access structure over finite fields. It amounts to solving a system of quadratic equations constructed from the given access structure and the corresponding adversary structure. The system becomes a linear system for binary codes. An algorithm is also given for finding the adversary structure for any given access structure. [ABSTRACT FROM AUTHOR]

During the past ten years, various types of HP-UHP metamorphic rocks have been discovered in the South Altyn Tagh, the North Qaidam and the North Qinling (秦岭) in the West and Middle Central China orogen. The UHP rocks, as lentoid bodies in regional gneisses, include eclogite (garnet-bearing pyroxenite), garnet peridotite and various pelitic or felsic gneisses. There are many records of minerals and microstructures of exsolution indicate the UHP metamorphism, such as coesite (or its pseudomorph), diamond, exsolution of clinopyroxene/amphibole/+rutile or rutile+quartz+apatite in garnet, exsolution of quartz in omphacite and exsolution of kyanite+spinel in precursor stishovite. The discovery of microstructure evidence for the presence of precursor stishovite in typical Alrich gneiss from the South Altyn Tagh reveals continental subduction and exhumation to and from a depth of more than 350 km. It is the petrological record of the deepest subduction and exhumation of continental rock in the world. The in situ zircon U-Pb dating using LA-ICP-MS or SHRIMP methods shows that the metamorphic ages of the HP-UHP rocks in the South Altyn Tagh, the North Qaidam and the North Qinling are 475-509, 420-457, and 485-514 Ma, respectively. The metamorphic ages of HP-UHP rocks in the North Qaidam are 20-80 Ma younger than those in the South Altyn Tagh and the North Qinling, and the metamorphic ages do not systematically increase or decrease from the South Altyn Tagh through the North Qaidam to the North Qinling. The absence of time transgressive variety of the metamorphism in the three regions does not support the hypothesis that the HP-UHP rocks in these regions form the same HP-UHP metamorphic zone. And the HP-UHP rocks in these regions can not be simply correlated to the collision between the North China plate and the South China plate. At present, the study of the HP-UHP rocks in the West and Middle Central China orogen faces several key issues or challenges, such as: (1) the continental subduction to the mantle depth of stishovite stability field (>9 GPa) is occasional or universal; (2) the mechanism of exhumation for the continental rocks subducted to the depth of stishovite stability field (>300 km); (3) the tectonic setting and geodynamical mechanism of producing the HP-UHP metamorphic zones in the South Altyn Tagh, the North Qaidam and the North Qinling. Further studies aiming at these problems will make important progress not only in metamorphism of the HP-UHP rocks in the West and Middle Central China orogen, but also in continental deep subduction and exhumation in solid earth science. It will also contribute to the establishment of the theory of continental deep subduction. [ABSTRACT FROM AUTHOR]

Integrated zircon U-Pb dating and whole rock geochemical analyses have been carried out for two typical S- and I-type granitoids in the north Qinling. Zircon dating by SIMS of the Piaochi S-type granitoids yields an emplacement age of 495±6 Ma. The granitoids show whole-rock ɛ Nd( t)=−8.2–−.8.8, zircon ɛ H f ( t)=−6–−39. The Huichizi I-type granitoids have emplacement ages of 421±27 Ma and 434±7 Ma established by LA-ICP-MS and SIMS methods, respectively. Their whole-rock ɛ Nd( t)=−0.9–0.9 and zircon ɛ Hf( t)=−11–8.4. Combined with statistical analyses of 28 zircon ages of granitoid plutons collected from the literature, Paleozoic magmatism in the north Qinling can be divided into three stages. The first-stage magmatism (∼505−470 Ma) mainly occurred in the east part of the north Qinling and has features of an I-type arc, associated with which are S-type granitoids such as Piaochi pluton. The early granitoids (∼505−490 Ma) have close spatio-temporal relations to ultra-high-pressure (UHP) rocks, and thus are interpreted as an oceanic subduction system along a continental margin. The second-stage magmatism (∼450−422 Ma) occured through the whole north Qinling, and is characterized by I-type granitoids represented by the Huichizi pluton. The magma is interpreted as partial melting of lower crust mixed by mantle-derived magma in a collisional setting with the uplift of terranes. The third-stage magmatism (∼415−400 Ma) is dominated by I-type granitoids and only took place in the middle part of the north Qinling, and is regarded as a late-stage collision. The spatial and temporal variations of the Qinling Paleozoic magmatism reveal protracted subduction/collision. The subduction was initiated from the east part of the north Qinling, earlier than that in the Qilian-northern Qaidam, Kunlun, and northern Dabie regions. This demonstrates variations in time of subduction, accretion and collision of separate blocks or terranes in the orogenic systems in central China. [ABSTRACT FROM AUTHOR]

Late Early Paleozoic mafic-ultramafic dykes and volcanic rocks from the South Qinling belt are characterized by ɛNd( t) = +3.28 − +5.02, (87Sr/86Sr)i = 0.70341 − 0.70555, (206Pb/204Pb)i = 17.256 − 18.993, (207Pb/204Pb)i = 15.505 − 15.642, (208Pb/204Pb)i = 37.125 − 38.968, Δ8/4=21.18 − 774.43, Δ7/4 = 8.11 − 18.82. These charac-teristics suggest that they derived from a Middle Neoproterozoic mantle with isotopic compositions of mixed HIMU, EMII and minor EMI components. We interpret that these rocks were melting products of depleted mantle modified by subducted ancient oceanic crust and continental margin sediments along the northern margin of Yangtze block during Early Neoproterozoic. [ABSTRACT FROM AUTHOR]

The properties and tectonic significance of the fault bound zone on the northern margin of the Central Tianshan belt are key issues to understand the tectonic framework and evolutionary history of the Tianshan Orogenic Belt. Based on the geological and geochemical studies in the Tianshan orogenic belt, it is suggested that the ophiolitic slices found in the Bingdaban area represent the remaining oceanic crust of the Early Paleozoic ocean between the Hazakstan and Zhungaer blocks. Mainly composed of basalts, gabbros and diabases, the ophiolites were overthrust onto the boundary fault between the Northern Tianshan and Central Tianshan belts. The major element geochemistry is characterized by high TiO2 (1.50%–2.25%) and MgO (6.64%–9.35%), low K2O (0.06%–0.41%) and P2O5 (0.1%–0.2%), and Na2O>K2O as well. Low ΣREE and depletion in LREE indicate that the original magma was derived from a depleted mantle source. Compared with a primitive mantle, the geochemistry of the basalts from the Bingdaban area is featureded by depletion in Th, U, Nb, La, Ce and Pr, and unfractionated in HFS elements. The ratios of Zr/Nb, Nb/La, Hf/Ta, Th/Yb and Hf/Th are similar to those of the typical N-MORB. It can be interpreted that the basalts in the Bingdaban area were derived from a depleted mantle source, and formed in a matured mid-oceanic ridge setting during the matured evolutionary stage of the Northern Tianshan ocean. In comparison with the basalts, the diabases from the Bingdaban area show higher contents of Al2O3, ΣREE and HFS elements as well as unfractionated incompatible elements except Cs, Rb and Ba, and about 10 times the values of the primitive mantle. Thus, the diabases are thought to be derived from a primitive mantle and similar to the typical E-MORB. The diabases also have slight Nb depletion accompanying no apparent Th enrichment compared with N-MORB. From studies of the regional geology and all above evidence, it can be suggested that the diabases from the Bingdaban area were formed in the mid-oceanic ridge of the Northern Tianshan ocean during the initial spreading stage. [ABSTRACT FROM AUTHOR]

Paleozoic cherts from the Mianlüe and the Erlangping ophiolite zones of the Qinling orogenic belt are characterized by low Si/Al ratios (52.14 - 683.52 in the Mianlüe cherts, 12.29 - 58.62 in the Erlangping cherts), Fe2O3 (0.01 - 0.35 and 0.02 - 1.24) and high Al2O3/(Al2O3+Fe2O3) ratios (0.82 - 0.99 and 0.83 - 0.99). The negative correlation between Si2O and Al2O3 in the cherts reflects the important role of terrigenous components. The Erlangping cherts have Lan/Cen=0.9 - 1.15 and Ce/Ce*=0.95 - 1.15 with low contents of V, Ni and Cu, consistent with those of cherts forming on the continental margin. In contrast, the Ce/Ce* ratios of the Mianlüe cherts range from 0.71 to 1.18 and Lan/Cen from 0.88 to 1.43 with slightly high V, Ni and Cu, which are similar to cherts found in the mid-ocean ridges and pelagic basins. Combined with the features of basic lavas associated with the cherts, it is suggested that during the Paleozoic, when the back-arc basin represented by the Erlangping ophiolite commenced shrinking in size in the mid-Ordovician, the southern Qinling was still in an extensional regime and finally grew into a new limited oceanic basin in the early Carboniferous. [ABSTRACT FROM AUTHOR]

The early Paleozoic alkali dyke swarms in the Ziyang-Langao areas of south Qinling are characterized by bimodal volcanic association. They show the patterns of enriched LREE with high fractionation of light and heavy REE and enrichment of incompatible elements in the primitive mantle-normalized spider-diagrams with peaks of Ba and Nb and valleys of Pb and Sr. The ratios of Ta/Hf are larger than 0.3 and those of Th/Ta less than 1.6, indicating that they were derived from enriched mantle sources closely related to plume. The occurrence of alkali dyke swarm demonstrates an extensional event of crust resulting from deep plume activity in the Qinling orogeny during early Paleozoic. The rifting extension could not continue due to the short activity of plume. Consequently, no new oceanic basin was formed. [ABSTRACT FROM AUTHOR]

Presents a study that examined the geochemistry of basic dykes in the Wudang block of south Qinling, China and discussed their tectonic significance. Regional geology; Geochemistry of the basic dykes; Origin and tectonic implications.

Presents a study that focused on the strontium, neodymium, lead and oxygen isotopes of basic dyke swarms in the Wudang Block and basic volcanics of the Yaolinghe Group in China. General geology; Sample and analysis; Isotope geochemistry of the elements.

High-temperature diffusion of major elements may obscure the records of early and peak metamorphic stages in granulites, while trace elements are more likely to preserve these records due to their lower diffusion rates. Thus, using calibrated REE-based thermobarometers has proved essential for reconstructing these key stages, drawing considerable attention and application from scholars. However, the precision of these thermobarometers depends on including both major and trace elements from coexisting minerals to define the correlation coefficients (A, B, and D) among mineral pairs, indicating that the elemental composition of these pairs can affect the results. Our study examines the mafic-ultramafic granulites in the southern granulite terrain, India, employing integrated methods such as petrography, mineral chemistry, phase equilibrium modeling, and REE-based thermobarometers. We aim to determine their metamorphic conditions and evolutionary history and to identify potential challenges in using REE-based thermobarometers. The garnet, clinopyroxene, and orthopyroxene in the mafic-ultramafic granulite samples display homogeneous compositional profiles, with pronounced Fe-Mg diffusion zones at the interfaces between garnet and clinopyroxene. Conversely, the profiles of trace elements within garnet and clinopyroxene are better preserved. Investigations into Fe-Mg exchange and randomly selected mineral pairs significantly influence the accuracy of REE-based thermobarometers. Fe-Mg exchange can increase in coefficient A, while decreasing coefficient B for light rare earth elements (LREEs) and increasing it for heavy rare earth elements (HREEs), ultimately resulting in over-estimations when calculating REE-based thermobarometers. For example, selecting major compositions with an Ex (=(XMgC−XMg0)/XMg0×100%\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$=\left(X_{\text{Mg}}^{C}-X_{\text{Mg}}^{0}\right)/X_{\text{Mg}}^{0}\times100\%$$\end{document}; where XMgC\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$X_{\text{Mg}}^{C}$$\end{document} is the value after Fe-Mg exchange, XMg0\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$X_{\text{Mg}}^{0}$$\end{document} is the value before Fe-Mg exchange; XMg=Mg/(Fe2++Mg)\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$X_{\text{Mg}}=\text{Mg}/\left(\text{Fe}^{2+}+\text{Mg}\right)$$\end{document}) value of ∼10 for calculation using the REE-in-Grt-Cpx thermobarometer will result in pressures and temperatures being ∼10 kbar and 30–40°C higher than the true values. Random pairing, such as selections based solely on the core or rim of minerals with changes in trace elements, can severely impact the distribution coefficient D, resulting in substantial discrepancies in thermobarometric calculations and potentially producing anomalous results. Thus, to minimize the impact of these factors, it is necessary to first analyze the profiles of major and trace elements in coexisting minerals before applying the REE-based thermobarometers to evaluate the P-T conditions of granulites. Based on this analysis, major element compositions less affected by Fe-Mg exchange (such as avoiding the selection of major compositions at the boundaries of minerals) and in relative equilibrium in trace element compositions among coexisting minerals (same growth periods) should be selected for pairing. Furthermore, integrating additional methods should also be considered when applying the REE-based thermobarometers, to prevent the misinterpretation of the P-T conditions obtained. [ABSTRACT FROM AUTHOR]

This paper first gives a regularity theorem and its corollary. Then, a new construction of generating hard random lattices with short bases is obtained by using this corollary. This construction is from a new perspective and uses a random matrix whose entries obeyed Gaussian sampling which ensures that the corresponding schemes have a wider application future in cryptography area. Moreover, this construction is more specific than the previous constructions, which makes it can be implemented easier in practical applications. [ABSTRACT FROM AUTHOR]