四川若尔盖北部寒武系太阳顶群硅质岩的热水沉积成因

四川若尔盖北部寒武系太阳顶群为金矿矿源层,硅质岩为其中的主要组成部分.研究矿源层的成因,硅质岩成因是关键所在.硅质岩已遭受变质成为微晶石英岩,以块状为主.岩石中均含有不等量的有机碳.岩石中还保留了较多的沉积组构.主要化学成分以SiO_2为主,结合微量元素及稀土元素等综合研究表明,太阳顶群硅质岩为热水沉积成因,硅可能来自下伏及深部地层.     

压碎台测定矿物包裹体在寻找内生金矿床中的应用

本文综述了液态包裹体压碎法的机理以及该方法在寻找热液型金矿中的应用,例举了用该方法判别岩石的含金性、圈定蚀变晕的空间位置等方面的实例。     

The evidence from inclusions in pumices for the direct degassing of volatiles from the magma to the hydrothermal fluids in the Okinawa Trough

This article presents the evidence in support of the direct magma degassing as the principal mechanism of volatiles releasing into the hydrothermal fluids in the Okinawa Trough, as contrasted to the argument for the hydrothermal stripping of volatiles from the volcanic rocks. Laser Raman microprobe and stepped-heating techniques are employed to determine the compositions and contents of the volatiles in pumices in the middle Okinawa Trough. The results show that the volatiles are similar to the gases in the hydrothermal fluids and hydrothermal minerals in composition, the mean percent content of each component and variation trend. This indicates the direct influence of magma degassing on the hydrothermal fluid. In addition, the contents of volatiles in pumices are rather low and do not support the hydrothermal stripping as the main mechanism to enrich the fluids with gases. The results are consistent with the idea that the direct magma degassing is more important than hydrothermal stripping in supplying gases to the hydrothermal fluids in the Okinawa Trough.     

试论与埃达克岩有关的热液矿床成因类型和成矿系列——以中国北方若干矿床为例

中国北方埃达克岩比较发育,有形成于早古生代岛弧环境、中生代中晚期陆弧环境及晚古生代中期和中生代中期大陆板块内环境3种埃达克岩.与形成于岛弧环境埃达克岩相关的热液矿床的成因类型为斑岩型,成矿系列为Cu-Au;与形成于陆弧环境埃达克岩相关的热液矿床的成因类型为斑岩型和浅成低温热液型,成矿系列为Au-Cu-Mo;与形成于板内环境埃达克岩相关的热液矿床的成因类型为斑岩型、夕卡岩和浅成低温热液型,成矿系列为Au-Cu-Pb-Zn.     

贵州盘县地区峨眉山玄武岩铜矿的成矿地质条件

以峨眉山玄武岩底部与中二叠统茅口组灰岩接触界面上赋存的黄见坑-哈树富铜矿带为例，论述了这一新类型玄武岩铜矿的成矿地质条件及峨眉山玄武岩浆喷-溢对Cu(Au、Pb、zn、Pt、Pd、Sb、F等)元素的富集和后期热液改造成矿作用，以扩大找矿思路。     

藏北美多锑矿床容矿硅质岩的地质地球化学特征及成因

文章通过野外地质调查和系统的岩石学、岩石化学、稀土及微量元素地球化学研究，探讨了藏北美多锑矿床容矿硅质岩的成因和大地构造环境。研究结果表明，美多锑矿容矿硅质岩以致密块状硅质岩为主；主元素化学组成表明，其形成时有大量陆源火山碎屑物质的介入；稀土元素组成及配分模式与热水硅质岩不同，显示其形成于大陆边缘环境；硅质岩和凝灰岩均呈Ba、Sr、P、Ti明显亏损和Nb弱亏损的特点，类似于成熟大陆弧花岗岩。     

The Paleoproterozoic McArthur River (HYC) Pb/Zn/Ag deposit of northern Australia: organic geochemistry and ore genesis

Polycyclic aromatic hydrocarbons (PAHs) in ore and mudstone within the McArthur River ore deposit show compound distribution patterns similar to those of hydrothermally generated petroleum in the Guaymas Basin and significantly different from those found in conventional oil. PAH abundances and their isomer distributions result from a temperature gradient between the source of mineralizing fluids and the sediments fringing the ore system during ore formation. Along with other geochemical, geological, paleobiological and mineralogical lines of evidence, these data provide strong evidence that the ore formed within partially lithified sediments under marine conditions. Given that the McArthur River ore body is an exquisitely preserved example of a sediment-hosted base-metal deposit, these results may be widely applicable. The McArthur deposit is also a rich repository of paleobiological information, allowing studies of the microbiology of ore formation and the paleobiology of an ancient hydrothermal system, as is discussed elsewhere.     

Fluxes of fluid and heat from the oceanic crustal reservoir

Recent discoveries define a global scale fluid reservoir residing within the uppermost igneous oceanic crust, a region of seafloor that is both warm and may harbor a substantial biosphere. This hydrothermal fluid reservoir formed initially within volcanic rocks newly erupted at mid-ocean ridges, but extends to the vastly larger and older ridge flanks. Upper oceanic crust is porous and permeable due to the presence of lava drainbacks, fissuring, and inter-unit voids, and this porosity and permeability allows active fluid circulation to advect measurable quantities of lithospheric heat from the crust to an average age of 65 Myr. A compilation of crustal porosities shows that this fluid reservoir contains nearly 2% of the total volume of global seawater. Heat flow and sediment thickness data allow calculation of reservoir temperatures, predicting 40°C mean temperatures in Cretaceous crust. Utilizing these temperature estimates, heat flow measurements and models for the thermal structure and evolution of the oceanic lithosphere, we have computed mean hydrothermal fluxes into the deep ocean as a function of plate age. The total hydrothermal volume flux into the oceans approaches 20% of the total riverine input and may contribute to the global seawater mass balance.     

Seawater transport and reaction in upper oceanic basaltic basement: chemical data from continuous monitoring of sealed boreholes in a ridge flank environment

Osmotically pumped fluid samplers were deployed in four deep-sea boreholes that were drilled during Ocean Drilling Program (ODP) Leg 168 on the eastern flank of the Juan de Fuca Ridge. Samplers were recovered from ODP Sites 1024 and 1027 and aliquots were analyzed for a variety of dissolved ions. Results from both of the samplers show a drastic change in the major ion composition within the first 20-40 days after the borehole was sealed at the seafloor followed by a more gradual change in composition. This gradual change ceased after 820 days at Site 1024 but continued throughout the 3-year deployment at Site 1027. We modeled this change in composition to estimate the flux of formation fluid through the open borehole. The rapid early change requires a flow of ∼1500 kg of formation fluid per day. The more gradual later change requires flow rates of 38 kg/day at Site 1024 and 17.5 kg/day at Site 1027. The latter fluxes require a minimum average specific discharge of meters to hundreds of meters per year through the surrounding basaltic matrix. Trace element data show surprisingly little contamination given the presence of steel casing, Li-organic-rich grease at each joint, cement, and drilling muds. Observed changes in trace element concentrations relative to those of bottom seawater provide a measure for the global significance of cool (23°C; ODP Site 1024) ridge flank hydrothermal systems relative to warm (64°C; Baby Bare and ODP Site 1027) hydrothermal systems and illustrate the importance of these cooler systems to global geochemical budgets.     

山西地震带热流体对强震活动的影响

以山西地震带热水点为基础资料，计算每个热水点的年热释放量，分析山西地区热水点的年热释放量与地震活动的关系。结果表明，热释放量低值区中小地震不活跃而强震活跃，高值区强震不活跃，而中小地震活跃。通过研究，还表明山西地区地壳活动所积累的能量，每年以热能形式释放的能量相当于一个7.3级地震，这对强震的孕育起到了缓解的作用，因此可能推迟或减少地震的发生。