Helium, Argon, and Xenon Isotopic Compositions of Ore-formingFluids in Jinding-Baiyangping Polymetallic Deposits,Yunnan, Southwest China

The Jinding superlarge lead and zinc deposit has attracted the attention of geologists of the world and its metallogenesis has long been in dispute. This paper takes the Jinding deposit and the Baiyangping Cu-Ag-Co deposit which was recently found at about 30 km north of Jinding as one ore belt, and, based on researches on the helium, argon, and xenon isotopic compositions of primary inclusions in ore-forming solutions of the main stage, the authors have found that the 3He/4He ratio of the ore-forming fluid is 2.7′ 10- 6 (varying from 0.19 to 1.97 Ra), the 4He/40Ar ratio (0.24- 3.12) is close to the mantle characteristic ratio, and the xenon isotopic composition and evolution show characters of the mantle xenon. The above results reveal the characteristics of mantle source and crust-mantle fluid mixing (mantle helium reaching 32%) and the metallogenic contributions of the deep processes in the Jinding-Baiyangping ore belt.     

鹿井铀矿床成矿流体演化的地球化学模拟

借助水文地球化学研究中水－岩相互作用地球化学模拟的思路和NETPATH2.0反向地球化学模拟软件,以华南鹿井铀矿床不同成矿阶段矿物包裹体分析资料为基础,对该矿床成矿流体的地球化学演化进行了初步的模拟。结果表明,NETPATH2.0所产生的溶液描述模型提供了比流体包裹体丰富得多的资料和信息,而溶液分配模型则计算出了每种元素（尤其是成矿元素）的若干种存在形式及每种形式的相对重要性。模拟所得到的地球化学模型揭示了矿床内主要相态在成矿流体不同演化阶段的质量迁移情况,为全面理解矿床的形成机制和动力学过程提供了新的途径。     

Genesis and evolution of hydrocarbons entrapped in the fluorite deposit of Koh-i-Maran, (North Kirthar Range, Pakistan)

The exceptional development of coeval hydrocarbon and aqueous fluid inclusions (FI) in fluorite from the MVT-type ore deposit of Koh-i-Maran, Baluchistan (North Kirthar range, Pakistan), provides samples which are representative of the ore-forming fluid and which support the hypothesis of petroleum migration in the province. Primary brines at 125°C (10 wt% equ. NaCl) and secondary CH₄-rich brines at 135°C (7 wt% equ. NaCl), are recognised to be associated with oil migration in the fluid inclusions. They support the model of a per ascensum MVT (Mississippi Valley Type) stratabound hydrothermal deposit. A pressure–temperature path of 120–125°C to 165–200 bars is calculated from microthermometric data and PVT modelling of hydrocarbon FI using the modified Peng–Robinson Equation of State (IFP software) from primary cogenetic inclusions (oil and brines).The composition of gas and oil fractions is obtained by a combination of Synchrotron FTIR microanalysis and gas chromatography performed on individual fluid inclusions. The oil entrapped as a coeval primary fluid phase is a light aliphatic normal oil in the range C₈–C₃₅ with a high CO₂ content. The brown solid phase found systematically in the oil is probably asphaltene resulting from precipitation after trapping of the heavy fraction, which commonly occurs by decreasing pressure and temperature and\or by CO₂ injection. Later CH₄-rich brine influx probably modified part of the oil in the primary fluid inclusions because degraded oil is observed within such inclusions. Biomarkers obtained by GC-MS analysis indicate a terpane distribution quite similar to the nearest oil seepage in the Gokurt area. This result and the high CO₂ content of organic fluid inclusions indicate a restricted/confined sedimentary environment for the source rock, which could correspond to the Eocene Carbonate formation with type-II organic matter. A possible additional input of gas from the Sambar formation is suggested as feasible. The link between the fluid inclusion data and the geodynamic evolution lead us to propose a circulation of basinal fluids driven mainly by the fault system during dewatering in the foredeep. In Pakistan, they are coeval to major compressional NW–SE Oligocene episode in the thrust belt. The origin of the fluorine may be found in the basin sediments as well as near the basement. The brines originated in salt structures recognized in eocambrian at the decollement level, the source rock was already mature.     

Incipient sediment motion based on turbulent fluctuations

The current study modifies the representation of the Shields parameter using turbulent strength,i.e.the root-mean-square(rms) fluid velocity.Experiments were done under a steady,uniform flow using eight sediment sizes with particle Reynolds numbers(Rep) ranging between 1.0(fine sediment) and 183.4(coarse sediment).Utilising the peak rms horizontal(u) values,the critical Shields parameter,θ_c,was calculated and a trend similar to the well-established Shields curve was developed.The analysis was extended to the Shields curve obtained based on the critical shear velocity,Reynolds shear stress,and data extracted fro m the oscillating grid-turbulence experiments.Results show that turbulent fluctuations are crucial for the incipient sediment motion and are essentially better predictors than the commonly used critical shear velocity.A quadrant analysis to identify the role of turbulent bursting events in incipient sediment motion also was done where sweeps and ejections are dominant for finer and coarser sediment sizes,respectively.     

Fluid evolution in base‐metal sulphide mineral deposits in the metamorphic basement rocks of southwest Scotland and Northern Ireland

The Dalradian and Ordovician–Silurian metamorphic basement rocks of southwest Scotland and Northern Ireland host a number of base‐metal sulphide‐bearing vein deposits associated with kilometre‐scale fracture systems. Fluid inclusion microthermometric analysis reveals two distinct fluid types are present at more than half of these deposits. The first is an H₂O–CO₂–salt fluid, which was probably derived from devolatilization reactions during Caledonian metamorphism. This stage of mineralization in Dalradian rocks was associated with base‐metal deposition and occurred at temperatures between 220 and 360°C and pressures of between 1.6 and 1.9 kbar. Caledonian mineralization in Ordovician–Silurian metamorphic rocks occurred at temperatures between 300 and 360°C and pressures between 0.6 and 1.9 kbar. A later, probably Carboniferous, stage of mineralization was associated with base‐metal sulphide deposition and involved a low to moderate temperature (T_h 70 to 240°C), low to moderate salinity (0 to 20 wt% NaCl eq.), H₂O–salt fluid. The presence of both fluids at many of the deposits shows that the fractures hosting the deposits acted as long‐term controls for fluid migration and the location of Caledonian metalliferous fluids as well as Carboniferous metalliferous fluids. Copyright © 2004 John Wiley & Sons, Ltd.     

临清坳陷德南洼陷含油气性的流体包裹体分析

应用流体包裹体观察和激光拉曼探针等微观技术对临清坳陷东北部的德南洼陷流体包裹体特征及成分、压力等物理化学条件的研究表明,研究区共有6种类型的包裹体:单相盐水包裹体、富液相包裹体、富气相包裹体、含液态CO2三相包裹体、富液态烃有机包裹体、富气态烃有机包裹体,其中富液态烃有机包裹体的均一温度为100～140°C的较多.包裹体的液相成分主要为H2O和Cl-,气相成分主要为CO2、CH4以及微量的C2H6等,包裹体成分研究结果表明在古近系和新近系中主要为未成熟-低成熟的液态烃流体活动;在古生界及部分上部层段中主要为成熟、高成熟的气态烃流体活动.根据盐水溶液包裹体的均一温度和冷冻温度计算得出研究区的流体压力为10～95 MPa,其中,在烃类流体大量排出运移时期经历过压力由突破到释放的过程;初步评价了区内的油气有利远景区.     

CL植物胶复合无固相冲洗液在复杂地层绳索取心钻进中的应用与研究

为满足复杂地层绳索取心钻探技术的需要,寻找、配制了既能代替泥浆具有良好的护壁堵漏性能,又能满足绳索取心钻进技术要求的CL植物胶复合无固相冲洗液。详细介绍了CL植物胶复合无固相冲洗液的配方和配制工艺、性能指标测试与评价、护壁机理认识及应用效果。     

流体 花岗岩 金矿

流体地质研究是当代地学研究中的重要前沿课题，已成为发展地质科学、建立新的知识体系的一个主要支柱和知识生长点。本文阐述了当今国内外流体的研究现状、发展水平、流体的涵义、性质、研究方法和研究重点及其与板块构造、变质作用、岩浆作用、成矿作用、成矿作用的重要意义。流体地质为地质科学提出了许多新的研究机会和挑战。该文在简要评述当今花岗岩研究现状的基础上，对花岗岩与金矿的关系进行了深入的讨论，指出了不同成因类型的花岗岩与金矿有着完全不同的关系。人们所说的花岗岩与金矿关系多数情况下应考虑是流体作用的结果。最后指出加强流体地质研究对提高河南地质与金矿的研究水平具有十分重要的实际意义和理论意义。     

pH值对适于页岩气储层的SDBS压裂液性能的影响研究

在低渗、低孔隙率页岩气储层压裂改造过程中,压裂液体系的pH值直接影响地层中的造缝、稳缝效果。pH值对阴离子表面活性剂压裂液的粘度、表面张力和页岩膨胀抑制性影响很大。通过改变阴离子表面活性剂的浓度,测定了在不同pH值条件下压裂液体系基本性能的变化。研究表明：SDBS压裂液体系的粘度随着pH值的增加先增大后减小,在pH值=9时达到最大;体系在pH值=5时降低体系表面张力的能力最好;页岩的膨胀量随着pH值的增大逐渐增大,在pH=7时膨胀量最大,且随着pH值的进一步增大,页岩膨胀量先减小后增大,在pH值=9时膨胀量最小;当体系的pH值一定时,SDBS在临界胶束浓度状态能够最大程度抑制页岩的膨胀。从化学微观角度上分析了pH值对SDBS压裂液性能的影响,有利于SDBS压裂液体系配方优化。