六盘山弧形构造带铜多金属矿床的成矿环境

六盘山弧形构造带位于青藏高原东北缘,自震旦-寒武纪以来,经历了"威尔逊旋回"构造演化.在陆内裂谷和板块俯冲阶段,成矿类型主要为海底火山块状硫化物型和与韧性剪切作用有关的构造蚀变岩型,而在碰撞造山和陆内造山阶段,成矿类型演变为与大型推覆体构造有关的似层状热液型,显示出不同构造演化阶段所反映的成矿环境不同.     

阿尔金山中段清水泉—茫崖蛇绿构造混杂岩带地质特征

清水泉—茫崖蛇绿构造混杂岩带沿阿尔金山南坡分布,呈醒目的"绿色岩带",其主要由蛇绿岩、蛇绿岩上覆岩系和元古代外来岩片或岩块组成,现多为构造透镜体,蛇绿岩上覆岩系具远洋深海沉积特征;岩石地球化学资料研究证明,蛇绿岩中的玄武岩与洋内岛弧拉斑玄武岩相似;同位素测年结果显示蛇绿岩形成于早古生代,蛇绿岩源自亏损的软流圈地幔,同时有富集地幔物质加入,暗示早古生代研究区曾出现过小洋盆构造环境。     

西藏冈底斯矿带成矿作用及远景分析

冈底斯带矿床众多,类型复杂,主要有斑岩型铜（金钼）矿床、矽卡岩型铁铜-铅-锌（银）矿床、层控铅-锌-银矿床、火山岩型金-银矿床及雄村式铜-金矿床。矿床地质特征和同位素年龄表明,冈底斯带南部的矿床与新特提斯洋壳向北俯冲-陆陆碰撞及碰撞期后的构造岩浆事件有关;冈底斯带北部的矿床与班公湖-怒江洋壳向南俯冲-陆陆碰撞及碰撞期后构造岩浆事件有关。冈底斯带与洋壳的俯冲-碰撞有关的岩浆活动强烈,成矿条件优越。西藏高原在碰撞后发生了快速抬升剥蚀,部分矿床顶部出现低温组合矿化,多数矿床保存良好。     

西藏冈底斯带石炭纪—二叠纪岛弧造山作用：火山岩及地球化学证据

系统研究了西藏冈底斯带石炭纪—二叠纪火山岩的时空分布、岩相学、元素及Sr、Nd、Pb 同位素地球化学和构造环境、源区性质,并与喜马拉雅带二叠纪火山岩进行了对比研究。冈底斯带石炭纪—二叠纪火山岩近东西向集中分布在冈底斯构造带中北部地带,空间上从东至西火山活动的强度和规模渐次减小,时间上从早至晚火山活动的强度和规模总体由弱到强。冈底斯带石炭纪—二叠纪火山岩形成于活动大陆边缘的岛弧构造环境,从早到晚岛弧造山作用经历了初始岛弧→早期岛弧→成熟岛弧的发展演变过程,火山岩浆来源于富集型地幔部分熔融作用,原始岩浆在形成和演化的过程中有俯冲洋壳及随带的深海沉积物和再循环进人地慢的地壳物质组分的强烈混染,明显不同于受地壳物质组分强烈混染的喜马拉雅带二叠纪陆缘裂陷型火山岩。综合研究冈底斯带及其邻区近年来的最新调查与研究成果,从北向南拟建了石炭纪—二叠纪冈底斯岛弧→雅鲁藏布江弧后裂谷盆地→喜马拉雅陆缘裂陷盆地的弧盆系时空结构演化模式,探讨了冈瓦纳大陆北缘石炭纪—二叠纪活动大陆边缘的岛弧造山作用与青藏高原古特提斯演化的耦合关系及其动力学机制,讨论了冈底斯带松多乡榴辉岩的形成过程。     

The double solid reactant method: II. An application to the shallow groundwaters of the Porto Plain,Vulcano Island (Italy)

This paper presents an example of application of the double solid reactant method (DSRM) of Accornero and Marini (Environmental Geology, 2007a), an effective way for modeling the fate of several dissolved trace elements during water–rock interaction. The EQ3/6 software package was used for simulating the irreversible water–rock mass transfer accompanying the generation of the groundwaters of the Porto Plain shallow aquifer, starting from a degassed diluted crateric steam condensate. Reaction path modeling was performed in reaction progress mode and under closed-system conditions. The simulations assumed: (1) bulk dissolution (i.e., without any constraint on the kinetics of dissolution/precipitation reactions) of a single solid phase, a leucite-latitic glass, and (2) precipitation of amorphous silica, barite, alunite, jarosite, anhydrite, kaolinite, a solid mixture of smectites, fluorite, a solid mixture of hydroxides, illite-K, a solid mixture of saponites, a solid mixture of trigonal carbonates and a solid mixture of orthorhombic carbonates. Analytical concentrations of major chemical elements and several trace elements (Cr, Mn, Fe, Ni, Cu, Zn, As, Sr and Ba) in groundwaters were satisfactorily reproduced. In addition to these simulations, similar runs for a rhyolite, a latite and a trachyte permitted to calculate major oxide contents for the authigenic paragenesis which are comparable, to a first approximation, with the corresponding data measured for local altered rocks belonging to the silicic, advanced argillic and intermediate argillic alteration facies. The important role played by both the solid mixture of trigonal carbonates as sequestrator of Mn, Zn, Cu and Ni and the solid mixture of orthorhombic carbonates as scavenger of Sr and Ba is emphasized.

滇西北永胜地区主要活动断裂与活动构造体系

位于滇西北断陷带东北部、程海-宾川断裂带北端的永胜地区上新世以来断裂活动强烈,构造地貌特征显著。永胜地区1:50000活动构造填图发现,区内共存在各类断裂14条。其中金官断裂（F₁）、永胜断裂（F₂）、木耳坪羊坪断裂（F₃）三者规模最大,活动性亦远超其他断裂,属于程海-宾川断裂带的一级分支断裂,其他断裂为程海-宾川断裂的二级分支断裂。构造地貌特征、错断地质体及擦痕统计等均指示区内断裂现今主要以伸展正断活动为主,根据活动性的差异可将其分为强、较强、中等、弱、极弱5类,其中金官断裂的活动性最强,垂向活动速率可达0.20~0.26 mm/a。对永胜地区主要断裂几何学、运动学特征的研究及动力学机制的讨论可知,永胜地区主要断裂在平面上构成向东突出的弧形旋扭构造体系,在剖面上表现为张扭性断裂常见的负花状构造;程海-宾川断裂带现今活动主要是在近南北向主压应力作用下产生的近东西向的伸展正断,并因为叠加了旋扭作用而具有一定左旋走滑。永胜地区的弧形旋扭构造体系及滇西北断陷带等均是在川滇内弧带顺时针旋转及南汀河断裂、畹町断裂与理塘断裂的走滑拉分共同作用下形成的。      

青山洞金矿床成因及找矿模型探讨

青山洞金矿位于湖南西南部的雪峰弧形构造成矿带上,是该成矿区带近年来新发现的重要金矿床。通过对青山洞金矿床地质特征的研究,分析其矿床成因类型属构造岩浆＋变质热液并以充填交代方式形成的韧脆性剪切带型金矿床,具硫化物-自然金矿石建造,工业类型为破碎蚀变岩型。并初步总结了成矿模式并建立了找矿模型,为寻找同类型金矿提供参考和指导。     

东天山板块构造分区、演化与成矿地质背景研究

围绕东天山找矿的基础地质构造问题，编制了新的1：50万东天山地区大地构造图和1：100万东天山地区成矿规律图。划分出新的大地构造单元，确认了中天山结晶轴的存在。将东天山地区显生宇以来的大地构造演化划分为洋壳扩张、俯冲岛弧、弧后盆地和碰撞造山期及造山期后伸展5个阶段，各阶段分别形成了对应的矿床和矿床组合，明确了主要矿床如土屋铜矿（泥盆纪－早石炭世增生弧背景）、黄山－香山铜镍矿（早二叠世同碰撞背景）的成矿时代和成矿环境。     

滇西北独龙江花岗岩及岩浆作用特征

滇西北独龙江地区的燕山期花岗岩可划分为6个单元，归并为早，晚2个序列。早期－龙岗不若序列由巴坡，东哨启等2个单元组成，生成于晚侏罗世－早白垩世，为壳幔混源岩浆形成，属火山弧花岗岩，是班公湖－东巧－怒江结合带俯冲消减的产物，晚期－独龙江序列由机独，其期，麻毕当，斯拉罗等4个单元组成，生成于晚白晋世，为壳源花岗岩，形成于同碰撞环境。是班公湖－东巧－怒江结合带碰撞造山的物质记录。     

Abundance and distribution of PGE and Au in the island-arc mantle: implications for sub-arc metasomatism

Ultramafic xenoliths from a veined mantle wedge beneath the Kamchatka arc have non-chondritic, fractionated chondrite-normalized platinum-group element (PGE) patterns. Depleted (e.g., low bulk-rock Al₂O₃ and CaO contents) mantle harzburgites show clear enrichment in the Pd group relative to the Ir group PGEs and, in most samples, Pt relative to Rh and Pd. These PGE signatures most likely reflect multi-stage melting which selectively concentrates Pt in Pt–Fe alloys while strongly depleting the sub-arc mantle wedge in incompatible elements. Elevated gold concentrations and enrichment of strongly incompatible enrichment (e.g., Ba and Th) in some harzburgites suggest a late-stage metasomatism by slab-derived, saline hydrous fluids. Positive Pt, Pd, and Au anomalies coupled with Ir depletions in heavily metasomatized pyroxenite xenoliths probably reflect the relative mobility of the Pd and Ir groups (especially Os) during sub-arc metasomatism which is consistent with Os systematics in arc mantle nodules. Positive correlations between Pt, Pd, and Au and various incompatible elements (Hf, U, Ta, and Sr) also suggest that both slab-derived hydrous fluids and siliceous melts were involved in the sub-arc mantle metasomatism beneath the Kamchatka arc.