福建省东部火山岩地区银矿成矿地质条件及找矿方向

通过对该区银矿床地质特征、成矿地质条件和成矿规律的研究，将区内银矿按成因、成矿作用、矿床地质特征等划分为三类六型。指出了火山－次火山热液型银矿是本区银矿的重要类型。总结了银矿的找矿标志，提出了本区银矿的主攻类型和主攻地区。     

内蒙古乌拉山金矿带中大桦背花岗岩与金矿床成因联系探讨

乌拉山金矿带大体背花岗岩成因属陆壳（改造）重熔型。花岗岩在成矿作用中的贡献，不仅能直接提供矿源，而且更重要的是间接提供矿源，花岗岩与金矿床在成因上、空间上、时间上有着密切联系，是形成（花岗岩）与被形成（矿床）的关系。指明乌拉山金矿具有三位一体成矿地质条件，即大古代变质岩系是金等成矿元素的提供者──—成矿基础，中生代构造──—岩浆活动是金等成矿元素的地质营力──—关键成矿作用，随之而进行的是金沿着构造裂隙（与之配套的断裂构造）集中、沉淀的成矿作用。     

The Evolutionary History of Ore-forming Processes of Metallic Ore Deposits in Northern Guangxi1

Abstract The northern Guangxi region is an important rare metal, rare earth metal and polymetallic metallogenic province. In the region there exist five metallogenic series and two metallogenic subseries, whose metallogenesis shows features of polycyclic spiral evolution throughout the geological history. As far as various cycles are concerned, mantle-derived ore substances were reduced while crust-derived ore substances increased from early to late times; in the whole geological evolutionary history, mantle-derived substances decreased gradually while crust-derived ones increased. Meanwhile ore element associations became more and more varied. In terms of space, mineralization migrated from the old basement outwards, i.e. from west to east during the Precambrian, and from north to south during the Phanerozoic, and again from east to west during the Yanshanian.     

山东灵山沟金矿床的矿化阶段划分及成矿意义

灵山沟金矿床位于招掖成矿带中部,是一个兼具“玲珑式”“焦家式”双重矿化特征的典型矿床.该矿床的成矿演化过程大致可划分为4个矿化阶段:I.微量金一黄铁矿一石英阶段;Ⅱ.金一石英一黄铁矿阶段;Ⅲ.金一石英一多金属硫化物阶段;Ⅳ.少量金一黄铁矿一石英一碳酸盐阶段.不同阶段具有不同的矿化特征和成矿意义.Ⅱ、Ⅲ矿化阶段为主成矿阶段.上述认识在整个胶东金矿化集中区具普遍性意义.     

中国东部地洼阶段应力场与锡成矿

中国东部地壳地洼阶段的热塑性变形应力场有利于锡成矿。构造应力场对锡成矿的控制作用,表现为对成矿域的矿液运移势和能量场的控制。推导获得矿液运移势的计算公式:Vi=-(a·K_0/u)·[exp(σ_1-σ_2)]·(σ_1+σ_2),表明地壳构造应力场对成矿域矿液的运移和成矿部位的选择提供了有利的动力学条件。     

康滇地轴石棉—会理段金矿化同位素地质研究

本文在研究康滇地轴石棉－会理段金矿化地质特征的基础上，分析了各类金矿化的同位素年龄、氢、氧、碳、硫和铅同位素的变化特征。指出了它们的流体类型、碳、硫、铅及金等成矿物质的来源，从而建立了本区金矿化的成矿序列。     

Multiple intrusions and low-pressure metamorphism in the central Old Woman Mountains, south-eastern California: constraints from thermal modelling

The Old Woman Mountains in south-eastern California are a Late Cretaceous low-pressure metamorphic terrane where multiple magmatic intrusions generated broad regions of elevated metamorphic temperatures. In the Scanlon Gulch area, two sheet-like, Late Cretaceous granitoid plutons are in contact with the Scanlon shear zone, a 1-km-thick sheet of isoclinally folded and transposed metamorphic rocks. The metaluminous Old Woman granodiorite underlies the shear zone and the peraluminous Sweetwater Wash granite overlies it. Both plutons record emplacement ages of ∼74 Ma. Thermobarometry and phase relations in the shear zone suggest that peak metamorphism was at 650 ± 50† C and 4.3 ± 0.5 kbar. Late Cretaceous metamorphic temperatures were less elsewhere in the Old Woman Mountains, away from the intrusions.
One-dimensional thermal models are used to investigate how differences in the time between the emplacement of plutons would affect the thermal evolution of the central Old Woman Mountains. The prediction of a thermal history inferred from petrological and thermochronological data requires the rapid emplacement of the two plutons around the shear zone; simulations with delays of more than 1 Myr in the emplacement of the second pluton failed to predict peak metamorphic temperatures. Calculations which consider only the emplacement of a single pluton yield metamorphic temperatures that are too low. The time separating the intrusions is by far the most sensitive parameter in the calculations; assumptions concerning the treatment of the initial geothermal gradient and the latent heat of crystallization have relatively small effects on the predicted thermal histories. Our results suggest that for certain geometries, relatively short-lived magmatic events involving rapid emplacement of multiple intrusions can produce low-pressure metamorphism.     

A two-stage evolution of Visakhapatnam-Paradip shelf,east coast of India,from magnetic studies

A detailed analysis of bathymetry and magnetic data of Visakhapatnam-Paradip shelf, east coast of India revealed three major structural lineaments over the shelf/slope of the area. Models derived from the anomalies associated with the trends indicate that trend A represents horst and graben type continental basement while trend B is due to a series of dyke intrusions. Trend C off Chilka lake forms the northward extension of 85°E lineation from deep sea Bengal Fan. A two stage evolution of the eastern continental margin of India has been inferred from the study of this part of the margin, viz., the rift stage evidenced by dyke intrusions of reverse polarity located within the inner part of the shelf and post-rift stage characterized by vertical tectonics in the form of a horst and graben type continental basement. The hotspot related aseismic 85°E ridge further complicated the tectonics of this part of the area.