Source Enrichment Control on the Scale of Magmatic-Hydrothermal W-Sn Mineralization:Insights from Triassic and Jurassic Magma Reservoirs in the Continental Crust,Xitian,South China

There are two factors,source composition and magmatic differentiation,potentially controlling W-Sn mineralization.Which one is more important is widely debated and may need to be determined for each individual deposit.The Xitian granite batholith located in South China is a natural laboratory for investigating the above problem.It consists essentially of two separate components,formed in the Triassic at ca.226 Ma and Jurassic at ca.152 Ma,respectively.The Triassic and Jurassic rocks are both composed of porphyritic and fine-grained phases.The latter resulted from highlydifferentiated porphyritic ones but they have similar textural characteristics and mineral assemblages,indicating that they reached a similar degree of crystal fractionation.Although both fine-grained phases are highly differentiated with elevated rare metal contents,economic W–Sn mineralization is rare in the Triassic granitoids and this can be attributed to less fertile source materials than their Jurassic counterparts,with a slightly more enriched isotopic signature and whole-rockεNd(226 Ma)of−10.4 to−9.2(2σ=0.2)compared withεNd(152 Ma)of−9.2 to−8.2(2σ=0.2)for the Jurassic rocks.The initial W-Sn enrichment was derived from the metasedimentary rocks and strongly enhanced by reworking of the continental crust,culminating in the Jurassic.

Construction Safety Management of Mechanical and Electrical Installation Projects

Various industries today rely on the support of electromechanical equipment,expanding its scope of application and leading to an increase in electromechanical installation projects.However,due to the high level of expertise required and the potential risks involved,it is crucial to emphasize safety management during construction.This paper delves into the significance of construction safety management for electromechanical installation projects,identifies common problems encountered during construction,and proposes solutions.This analysis aims to provide relevant personnel with essential guidance and references for managing electromechanical installation projects safely.

Magma Chamber Process of Post-collisional Magmatism: Insight from Textural and Elemental Characteristics of Plagioclase from the Tatun Volcanic Group, Northern Taiwan Volcanic Zone

The Taiwan mountain belt, one of the youngest orogenies in the world, is caused by the collision of the Luzon arc with the Eurasian margin, which leads to post-collisional extension and magmatism in the Northern Taiwan Volcanic Zone(NTVZ). The magma chamber process in this region has not previously been elucidated in detail. In this paper, the textural and compositional features of plagioclase phenocrysts in basalt from the Tatun Volcanic Group(TTVG) were studied to restrict the dynamics of magma system. Results show that the magma melts in TTVG are mainly sourced from the underlying MORB-like mantle wedge but influenced by incorporation of subduction components, causing the elevated Sr/Y and Ba/Y ratios in magma melts. The subduction components are mainly transported in the form of sediment melt. The plagioclase phenocrysts in the TTVG volcanic rocks are generally coarsely core-sieved with a clear rim. The An contents in the rims of plagioclase are much lower than those of cores, and elevated FeO concentrations are detected in the plagioclase rims. We propose there exists a double-layer magma chamber in this region. The core of the plagioclase was crystalized in the deeper quiescent magma chamber(~21 km), which was subsequently partially dissolved during the ascent of magma melt under H_(2)O-undersaturated condition, forming the typical coarsely sieved texture and synneusis. When this crystal-rich melt migrates into the shallower chamber, water saturation is reached and more sodic plagioclase formed as the rim of phenocryst. Due to the considerably higher fO_(2) in the shallow chamber than in the deeper one, and the distribution of Fe between plagioclase and melt positively correlates with fO_(2), the FeO content in the plagioclase rim elevates in conjunction with increasing fO_(2).

Maceral evolution of lacustrine shale and its effects on the development of organic pores during low mature to high mature stage:A case study from the Qingshankou Formation in northern Songliao Basin,northeast China

Organic matter(OM)hosted pores are crucial for the storage and migration of petroleum in shale reservoirs.Thermal maturity and macerals type are important factors controlling the development of pores therein.In this study,six lacustrine shale samples with different thermal maturities from the first member of the Qingshankou Formation in the Songliao Basin,of which vitrinite reflectance(R_(o))ranging from 0.58% to 1.43%,were selected for a comparative analysis.Scanning electron microscopy(SEM)and reflected light microscopy were combined to investigate the development of organic pores in different macerals during thermal maturation.The results show that alginite and liptodetrinite are the dominant primary macerals,followed by bituminite.Only a few primary organic pores developed in the alginite at the lowest maturity(R_(o)=0.58%).As a result of petroleum generation,oil-prone macerals began to transform to initial-oil solid bitumen at the early oil window(R_(o)=0.73%)and shrinkage cracks were observed.Initial-oil solid bitumen cracked to oil,gas and post-oil bitumen by primary cracking(R_(o)=0.98%).Moreover,solid bitumen(SB)was found to be the dominant OM when R_(o)>0.98%,which indicates that SB is the product of oil-prone macerals transformation.Many secondary bubble pores were observed on SB,which formed by gas release,while devolatilization cracks developed on migrated SB.Additionally,at the late oil window(Ro?1.16%),migrated SB filled the interparticle pore spaces.With further increase in temperature,the liquid oil underwent secondary cracking into pyrobitumen and gas,and spongy pores developed on the pyrobitumen at higher levels of maturity(Ro=1.43%),which formed when pyrobitumen cracked into gas.Vitrinite and inertinite are stable without any visible pores over the range of maturities,verifying their low petroleum generation potential.In addition,it was concluded that clay minerals could have a catalytic effect on the petroleum generation,which may explain why organicclay mixtures had more abundant pores than single OM particles.However,after R_(o)>0.98%,authigenic minerals occupied the organic pore spaces on the organic-clay mixtures,resulting in fewer pores compared to those observed in samples at the early to peak oil window.

3D forward modeling and response characteristics of low-resistivity overburden of the CFS-PML absorbing boundary for ground-well transient electromagnetic method

This study used the stable and convergent Dufort-Frankel method to differentially discretize the diffusion equation of the ground-well transient electromagnetic secondary field.The absorption boundary condition of complex frequency-shifted perfectly matched layer(CFS-PML)was used for truncation so that the low-frequency electromagnetic wave can be better absorbed at the model boundary.A typical three-dimensional(3D)homogeneous half-space model was established and a low-resistivity cube model was analyzed under the half-space condition.The response patterns and drivers of the low-resistivity cube model were discussed under the influence of a low-resistivity overburden.The absorption boundary conditions of CFS-PML significantly affected the low-frequency electromagnetic waves.For a low-resistivity cube around the borehole,its response curve exhibited a single-peak,and the extreme point of the curve corresponded to the center of the low-resistivity body.When the low-resistivity cube was directly below the borehole,the response curve showed three extreme values(two high and one low),with the low corresponding to the center of the low-resistivity body.The total field response of the low-resistivity overburden was stronger than that of the uniform half-space model due to the low-resistivity shielding effect of electromagnetic waves.When the receiving-transmitting distance gradually increased,the effect of the low-resistivity overburden was gradually weakened,and the response of the low-resistivity cube was strengthened.It was affected by the ratio of the overburden resistivity to the resistivity of the low-resistivity body.

Petrological and Geochemical Constraints on the Origin of Strongly Peraluminous Granitoids from the Triassic Guangtoushan Pluton in South Qinling

As an important part of the early Mesozoic granites in the South Qinling tectonic belt(SQTB),the Guangtoushan pluton provides a material basis for research on the composition of magma sources and the effects of peritectic assemblage entrainment(PAE)on the changes in the granite composition.As shown by the results of LA-ICP-MS zircon U-Pb dating,the Guangtoushan pluton was emplaced during the Late Triassic(214-212 Ma)and was formed in the post-collision stage between the SQTB and the Yangtze plate.The collected samples had high SiO_(2)content and low Cr and Ni contents,indicating that the magmas did not undergo significant crust-mantle mixing during their evolution.The Guangtoushan granitoids were distributed along the trend line of magmatic fractional crystallization in the F-An-Or diagram.This result,combined with the relatively homogeneous Sr-Nd isotopic composition,implies that the Guangtoushan pluton underwent slight assimilation and contamination.As can be inferred from the comparison between the compositions of the Guangtoushan granitoids and various fluid-absent experimental melts,the magma sources of the Guangtoushan granitoids contain a variety of materials,such as graywackes,pyroclastic graywackes,and pelites and are not derived from lower crustal mafic rocks.The correlation between the maficity and the major and trace elements further indicates that the strongly peraluminous granitoids from the Guangtoushan pluton was formed by the partial melting of biotite-bearing crustal rocks and its magmatic evolution was accompanied by the entrainment of clinopyroxenes and accessory minerals.

Surface property variations in flotation performance of calcite particles under different grinding patterns

基于料层粉碎工作方式,高压辊磨制备的矿物颗粒具有区别于其他磨矿方式制备颗粒的表面特性,对矿物浮选会产生较大的影响。本文研究了高压辊磨、颚式破碎、干式球磨、湿式球磨及湿式棒磨下方解石纯矿物颗粒的浮选行为,并通过比表面积、粒径分布、原子力学显微镜、表面电子能谱及动电位等手段表征了不同磨矿方式制备颗粒的表面特性以揭示其浮选机理。结果表明:当磨矿细度较低时,相比于其他磨矿方式高压辊磨制备的方解石颗粒在油酸钠和十二胺体系均能够获得更好的浮选指标;由磨矿方式导致的矿物颗粒比表面积、粒度分布、表面粗糙度、Fe^(3+)沾染物、键合能及Zeta电位差异是其浮选行为差异化的主要原因。

基于level set方法的含水层参数识别

简单介绍了level set方法的基本原理,并将其应用到含水层参数识别问题。将含水层中两种介质的界面看作level set函数的零水平集。首先给定一个初始界面,然后根据观测水头与计算水头之差,使lcvel set函数以一定方式运动,从而使计算出来的界面逐步逼近真实界面。文中给出了两个数值算例,结果表明该方法可以有效地处理含水层参数识别问题。

高压辊磨终粉磨工艺制备颗粒的均匀性分析（英文）

针对高压辊磨终粉磨工艺中存在的过磨和粒度不均匀现象,本文采用高压辊磨终粉磨、阳离子反浮选以及准静态料层粉碎模拟等试验方法从评价指标、工艺条件参数的影响、颗粒均匀性对浮选的影响及颗粒均匀性强化机制等方面展开研究。理论分析表明,对颗粒均匀性分析的评价指标必须涵盖均匀性系数和平均粒径两个方面;试验结果表明,高压辊磨终粉磨工艺中选粉机循环风机转速对颗粒均匀性影响最为明显,其次是高压辊磨机工作压力和辊缝,辊面转速的影响最弱;颗粒平均粒径对方解石浮选精矿品位有较大影响而均匀性系数对精矿回收率有较大影响,综合考虑浮选精矿回收率和品位,终粉磨制备颗粒的平均粒径最佳值为50~55μm、均匀性系数为1.1~1.2;为了提高产品颗粒均匀性,高压辊磨终粉磨工艺中有利于料层屏蔽效应和密实效应的操作参数应该得到强化。

Finite element modelling of the geodynamic processes of the Central Andes subduction zone:A Reference Model

This paper presents preliminary results of three-dimensional thermomechanical finite-element models of a parameter study to compute the current temperature and stress distribution in the subduction zone of the central Andes （16°S-26°S） up to a depth of 400 km, the bottom of the asthenosphere. For this purpose a simulation running over c. 50,000 years will be realized based on the geometry of a generic subduction zone and an elasto-viscoplastic Drucker-Prager rheology. The kinematic and thermal boundary conditions as well as the rheological parameters represent the current state of the study area. In future works the model will be refined using a systematic study of physical parameters in order to estimate the influence of the main parameters （e.g. viscosity, fault friction, velocity, shear heating） on the results of the reference model presented here. The reference model is kept as simple as possible to be able to estimate the influence of the parameters in future studies in the best possible way, whilst minimizing comnutational time.

西昆仑造山带大红柳滩岩体年代学、成因及其构造意义（英文）

西昆仑造山带东部大红柳滩花岗岩体对于理解西昆仑造山带大陆演化具有重要的指示意义。本文对该花岗质岩体主、微量元素、Li-Sr-Nd-Hf同位素和锆石的U-Pb年龄进行了系统研究。LA-ICP-MS锆石U-Pb年龄数据显示,大红柳滩花岗岩体的侵位时代为(213±2.1)Ma,说明大红柳滩岩体形成于晚三叠世。地球化学数据显示该岩石SiO2含量为68.45%~73.62%,铝饱和指数(A/CNK)变化区间为1.11~1.21,A/NK为在1.52~1.67,属于富钾钙碱性过铝质花岗岩。岩石富集Rb、Th、K等大离子亲石元素,亏损Nb、Ta、P、Ti等高场强元素;大红柳滩花岗岩锶同位素初始比值为(87Sr/86Sr)i=0.7087~0.71574,εNd(t)=8.71~4.73;锆石176Hf/177Hf比值为0.2826181~0.2827683,εHf(t)值在0附近,与同时期的亏损地幔的εHf(t)偏离较远,二阶段模式年龄(tDM2)为974~1307 Ma;花岗岩样品的δ7Li含量为0.76‰~3.25‰,平均2.53‰。推测岩体为中元古代古老地壳物质部分熔融形成,同时可能有少量幔源物质的加入。综合前人研究成果,本文认为大红柳滩岩体形成于南昆仑地体和甜水海地体发生陆-陆碰撞造山过程的后碰撞伸展环境下,幔源岩浆底侵作用引起下地壳部分熔融的结果。

伊朗扎格罗斯地区Mansuri油田储集层物性模拟

以伊朗Mansuri油田50口井的常规测井资料为基础,优选人工智能算法,对Mansuri油田白垩系Ilam组4个层的孔隙度和渗透率分布进行模拟。首先利用5口有岩心物性分析资料的井,遴选出常规测井的声波时差、密度和中子孔隙度作为输入参数,采用反向传播人工神经网络(BP神经网络)和支持向量回归方法进行储集层孔隙度和渗透率计算,根据计算结果与岩心实测结果的相关性,选择采用BP神经网络法进行物性计算。然后,利用克里金地质统计算法,对Mansuri油田Ilam组4个层的孔隙度和渗透率分布进行模拟,结果表明,层2.1和层2.2为高孔隙度层,层1、层2.1和和层2.2高渗透层,层3为非储集层;储集层孔隙度和渗透率分布总体呈北部高、南部低的特点。

Petrology, Geochemistry and Tectonomagmatic Setting of Neshveh Intrusion (NW Saveh)

Neshveh intrusion is located in the NW of Saveh City and is a part of Orumieh-Dokhtar magmatic arc. This intrusion consists of quartz monzodiorite, granodiorite and granite that have intruded into the Eocene volcano-sedimentary rocks. This intrusion is high-K calk-alkaline and metaluminous and is classified as I-type granitoids. Field investigations along with petrographic and geochemical studies indicate that all phases of Neshveh intrusion are derived from a common magma source as a result of mineral differentiation. Different phases of this intrusion have low Mg#, Ni, Cr, Co and V which are indicative for higher evolution of magma during the magma ascent and before complete crystallization. All phases of Neshveh granitoid are characterized by LREE-rich patterns with high LREE/HREE ratio and negative Eu anomalies. Similarity of the mentioned patterns suggests a comagmatic source for these rocks and demonstrates the role of magmatic differentiation in their evolution. There are negative anomalies in the Nb and Ti along with positive anomalies of Rb, Ba, K and Pb on the spider diagrams. These anomalies are indicative for a subduction setting for magma source of these rocks. Geochemical studies indicate that the Neshveh granitoid is formed in a volcanic arc and active continental margin. In this base, it is assumed that this intrusion is formed as a result of Neo-Tethys oceanic lithosphere subduction beneath the Central Iran zone which is replaced in the Orumieh-Dokhtar magmatic arc.

Investigating the minimum detectable activity concentration and contributing factors in airborne gamma-ray spectrometry

In this study,the theory of minimum detectable activity concentration(MDAC)for airborne gamma-ray spectrometry(AGS)was derived,and the relationship between the MDAC and the intrinsic effi-ciency of a scintillation counter,volume,and energy res-olution of scintillation crystals,and flight altitude of an aircraft was investigated.To verify this theory,experi-mental devices based on NaI and CeBr 3 scintillation counters were prepared,and the potassium,uranium,and thorium contents in calibration pads obtained via the stripping ratio method and theory were compared.The MDACs of AGS under different conditions were calculated and analyzed using the proposed theory and the Monte Carlo method.The relative errors found via a comparison of the experimental and theoretical results were less than 4%.The theory of MDAC can guide the work of AGS in probing areas with low radioactivity.

Assessment of landslide susceptibility using DBSCAN-AHD and LD-EV methods

Landslide susceptibility assessment plays a vital role in understanding landslide information in advance and taking preventive as well as control measures. The need to initially specify the number of clusters, difficulty in handling noise and quantifying rainfall data, limits the application of traditional clustering models in landslide susceptibility assessment which then lowers their performance accuracy. Thus, to overcome these limitations, this study proposed an improved clustering algorithm titled the DBSCAN-AHD algorithm, which combines the traditional DBSCAN(Density Based Spatial Clustering of Application with Noise) algorithm and an Adaptive Hausdorff Distance(AHD) for landslide susceptibility modeling. Firstly, AHD was introduced to the traditional DBSCAN to quantify rainfall. Then,the DBSCAN-AHD grouped the mapping units with similar topology and geology characteristics into subclasses without specifying the number of clusters in advance for its ability to handle noise in the data.Furthermore, the LD-EV(landslide density or eigenvalues) approach was introduced to obtain the susceptibility levels using K-means algorithm. Finally,to verify the model’s performance, statistical indices and the area under the curve(AUC) were applied and compared to the traditional DBSCAN, KPSO, Kmeans and Hierarchical Clustering algorithms,whereby, the proposed model outperformed the others. Also, the obtained susceptibility map can provide references in taking relevant preventive and control measures.

Geological characteristics,metallogenic regularity,and research progress of lithium deposits in China

China is rich in abundant lithium resources characterized by considerable reserves and a concentrated distribution of metallogenic zones or belts,with proven reserves of 4046.8×10^(3) t(calculated based on Li_(2)O)by 2021.China is also a big consumer of lithium.By 2019,China’s lithium consumption in the battery sector alone had reached 99×10^(3) t,with an average annual growth rate of nearly 26%.China has become the world’s largest importer of lithium resources,showing a severely unbalanced relationship between supply and demand for lithium resources.Therefore,there is an urgent need for the prospecting,exploitation,and study of lithium resources in China.This study collected,organized,and summarized the data on the major lithium deposits in China,analyzed and compared the spatial-temporal distribution patterns,geological characteristics,and metallogenic regularity of these lithium deposits,and summarized the prospecting and research achievements over the last decade.The major lithium deposits in China are distributed in provinces and regions such as Qinghai,Jiangxi,Sichuan,Tibet,and Xinjiang.These deposits are mostly small in scale.According to different genetic types,this study divided lithium deposits into granitic pegmatite type,granite type,saline lake brine type,underground brine type,and sedimentary type,as well as new types including hot spring type and magmatic-hydrothermal type,and summarized the characteristics and key metallogenic factors of these different types of deposits.Sixteen metallogenic prospect areas of lithium deposits were delineated according to the deposit types and the distribution patterns of metallogenic belts.The paper introduced the research progress in major metallogenic models and lithium extraction techniques made over the past decade.Based on the comprehensive analysis of the prospecting potential of lithium deposits,the authors concluded that the future prospecting of lithium resources in China should focus on lithium metallogenic belts,the deep and peripheral areas of currently determined large-scale pegmatite-type lithium deposits,geophysical-geochemical anomalous areas with mineralization clues,and areas with developed large-scale low-grade associated granite-type and sedimentary lithium resources.The study aims to serve as a guide for the future prospecting of lithium deposits in China.

Evaluation of Maturity and Depositional Environment of Bitumen Shale of Asmari Reservoir's Caprock in Pazanan Oil Field with Use of GC-MS and Isotopic(δ^(13)C)&(δ^(34)S) Methods

The study of each part of petroleum system is necessary.However,recently,petroleum geologists focused their attention on the study of source rock, migration and accumulation with use of different geochemical methods.Of these,carbon isotope and biomarkers or chemical fossils are new scopes in petroleum geology especially in correlation.The member 1 of Gachsaran formation can be divided into 6 keybeds,among them the B keybed is

Gas generation from coal: taking Jurassic coal in the Minhe Basin as an example

The gas generation features of coals at different maturities were studied by the anhydrous pyrolysis of Jurassic coal from the Minhe Basin in sealed gold tubes at 50 MPa.The gas component yields(C1,C2,C3,i-C4,n-C4,i-C5,n-C5,and CO2);theδ13C of C1,C2,C3,and CO2;and the mass of the liquid hydrocarbons(C6+)were measured.On the basis of these data,the stage changes ofδ13C1,δ13C2,δ13C3,andδ13CO2 were calculated.The diagrams ofδ13C1–δ13C2 vs ln(C1/C2)andδ13C2–δ13C1 vsδ13C3–δ13C2 were used to evaluate the gas generation features of the coal maturity stages.At the high maturity evolution stage(T>527.6°C at 2°C/h),the stage change ofδ13C1 and the CH4 yield are much higher than that of CO2,suggesting that high maturity coal could still generate methane.When T<455°C,CO2 is generated by breaking bonds between carbons and heteroatoms.The reaction between different sources of coke and water may be the reason for the complicated stage change inδ13CCO2 when the temperature was higher than 455°C.With increasing pyrolysis temperature,δ13C1–δ13C2 vs ln(C1/C2)has four evolution stages corresponding to the early stage of breaking bonds between carbon and hetero atoms,the later stage of breaking bonds between carbon and hetero atoms,the cracking of C6+and coal demethylation,and the cracking of C2–5.Theδ13C2–δ13C1 vsδ13C3–δ13C2 has three evolution stages corresponding to the breaking bonds between carbon and hetero atoms,demethylation and cracking of C6+,and cracking of C2–5.

Quantitative Gas-in-place Comparison of Original and Bitumen-free Lacustrine Shale

Residual bitumen in organic-rich shale of oil windows exists widely, and its effect on the gas storage capacity of shale could be two-fold. Bitumen could occupy and block the nanopores of shale, thereby reducing the gas storage capacity. On the other hand, gas could be dissolved in bitumen in shale gas reservoirs, leading to enhanced gas storage capacity. To quantify the effect of bitumen on the gas-in-place(GIP) estimation of lacustrine organic-rich shale, the micropore characteristics and methane sorption capacity of original and bitumen-free shale from the Triassic Yangchang Formation of the Ordos Basin, combined with the methane dissolution capacity for the isolated bitumen, were analyzed and compared. GIP for the original and bitumen-free shale in the depth range of 500–2500 m was evaluated. The results show that micropores in the shale samples were mainly related to organic matter. Clay mineral-hosted pores contributed slightly to microporosity. Bitumen significantly reduced the micropore surface area and volume of the original shale, with average percentages of 28.09% and 51.26%, respectively. The methane sorption capacity decreased after bitumen removal. When normalized to the original shale mass, the sum of the methane sorption capacity for bitumen-free shale and the methane dissolution capacity for isolated bitumen was similar to the methane sorption capacity of the original shale, indicating that the lack of methane absorbed on bitumen is the main reason for the decrease in methane sorption capacity after bitumen removal. The contribution of absorbed methane on bitumen to sorbed methane in shale could be higher than 36.23%. Dual effects of bitumen on shale GIP were observed. A high content of bitumen(1.12%) increased the GIP of the shale samples, with an average percentage of 23.5% in the depth range of 500–2500 m, while a low content of bitumen(0.06%) decreased the GIP, with an average percentage of 13.6%.

A multi-stage triaxial testing procedure for low permeable geomaterials applied to Opalinus Clay

In many engineering applications,it is important to determine both effective rock properties and the rock behavior which are representative for the problem’s in situ conditions.For this purpose,rock samples are usually extracted from the ground and brought to the laboratory to perform laboratory experiments such as consolidated undrained(CU)triaxial tests.For low permeable geomaterials such as clay shales,core extraction,handling,storage,and specimen preparation can lead to a reduction in the degree of saturation and the effective stress state in the specimen prior to testing remains uncertain.Related changes in structure and the effect of capillary pressure can alter the properties of the specimen and affect the reliability of the test results.A careful testing procedure including back-saturation,consolidation and adequate shearing of the specimen,however,can overcome these issues.Although substantial effort has been devoted during the past decades to the establishment of a testing procedure for low permeable geomaterials,no consistent protocol can be found.With a special focus on CU tests on Opalinus Clay,this study gives a review of the theoretical concepts necessary for planning and validating the results during the individual testing stages(saturation,consolidation,and shearing).The discussed tests protocol is further applied to a series of specimens of Opalinus Clay to illustrate its applicability and highlight the key aspects.