The outer arc of the costa rican orogen (oceanic basement complexes of the Nicoya and Santa Elena Peninsulas)

The basement of the Costa Rican outer arc consists of two major complexes. The older is composed of peridotite-serpentinite, pillow lava and radiolarite; the younger is made up of gabbro-diorite, pillow lava, pyroclastic rocks and siliceous limestone.The observational data are interpreted as follows. The older pillow lavas are believed to be oceanic crust generated along the north-south-spreading Carnegie Ridge during the late Coniacian. The younger lavas flowed from fissures along a west-northwest-trending volcanic belt (Culebra arc) which developed in this crust during early to middle Campanian time, when it collided with the Chortis block. Paleomagnetic evidence suggests that the older sequence originated on the Southern Hemisphere, and the younger in the Northern.During the Paleocene, the crust fragmented and separated into the Caribbean and Cocos plates, probably as a result of the outer arc escaping the tectonic influence of the Carnegie Ridge and entering that of the ancestral East Pacific Rise. This fragmentation resulted in the formation of two parallel volcanic belts (San Antonio and Cachimbas arcs) in the inner deep (Tempisque Valley), which remained active throughout the Eocene. It is postulated that subduction of the Cocos beneath the Caribbean plate was initiated during Oligocene time and resulted in the formation of yet another volcanic belt (Tilarán-Talamanca arc). The outer arc was uplifted, folded, and thrust south westward. The resulting pattern shows a gradual clockwise rotation west to northwest, and north-astward migration of the volcanic arcs through time. Aeromagnetic and tectonic data indicate that differential uplift and later gravitational décollement of the sedimentary rock blanket characterize the tectonic deformation of singular volcanic belts, and that tectonic overprinting is usually restricted to one major phase.     

Factors of Localization and Forecasting of Ore Mineralization in the Dzhusa Pyrite–Polymetallic Deposit (Southern Urals)

An analysis of tectonic displacements along fractures and faults revealed changes in the character of tectonic deformations that resulted from tectonic evolution of the Magnitogorsk island arc. Structural conditions of localization of ore mineralization of various types were investigated in the open pit of the Dzhusa deposit. The block diagram of an ore shoot of the Dzhusa deposit, which is confined to intersection of NW-striking and sublongitudinal faults was constructed. Trends in the distribution of sites with enriched mineralization are slightly different for various metals. The obtained data make it possible to predict the localization of rich ore bodies at deeper levels of the deposit and to reveal new prospecting ore sites in the Terensai ore field.     

秦岭造山带重大地质事件、矿床类型和成矿大陆动力学背景

秦岭造山带由两条主缝合带（商丹、勉略缝合带）及其分划的三个地块（华北地块南缘、秦岭微地块和扬子地块北缘）组成。秦岭造山带是在晚太古一中元古代洋陆间杂构造基础上,于晚元古代一中三叠世经历现代板块构造体制的主造山期的华北、秦岭、扬子三板块依次沿商丹和勉略两条缝合带由南向北俯冲碰撞造山,奠定了基本构造格局,并由于后造山期强烈的陆内造山作用的叠加改造成复合型造山带。秦岭造山带内的金属矿床主要有热水喷流沉积型铅一锌矿床、火山喷流型块状硫化物、斑岩一矽卡岩型钼（钨）矿床、卡林一类卡林型金矿床、岩浆热液脉型金矿床和低温热液改造型汞锑矿床。造山带内的商丹和勉略缝合带产有部分岩浆分结或熔离型铬铁矿和铜镍硫化物矿床。沉积一变质成因铁矿床主要分布在扬予和华北古板块边缘。秦岭造山带造山过程与成矿作用演化存在时空耦合关系,因此研究秦岭造山带成矿事件对其不同时期地质事件的响应,对发展我国大陆成矿理论具有重要理论和实际意义。     

大兴安岭中南段布敦化铜矿床地质特征及成矿模式

大兴安岭中南段铜成矿带已探明铜矿床众多,矿化类型主要为热液脉型与斑岩型.布敦化铜矿床由于同时存在两种矿化类型而备受关注,然而针对该矿区内相邻两个矿段（金鸡岭、孔雀山）成矿特征差异性缘由尚未得到解释,有关该矿床成矿机制综合研究尚显薄弱,整体成矿模式亟待建立.在综合前人研究成果基础上,认为布敦化矿区如此小范围内存在两种矿化类型,有可能与晚侏罗世成矿阶段构造演化的不同相关。布敦化挤压带两侧地质体发生垂向位移,孔雀山矿段所在部位（上盘）相对上升,得以形成浅成高温热液脉型铜矿.（165±2）~151.95±0.73Ma,极有可能在金鸡岭矿段深部存在当时未上升的黑云母花岗闪长岩,其内、外接触带极有可能形成浸染状铜矿化,可以作为今后该矿段找矿方向.在上述认识基础上构建布敦化铜矿床成矿模式,为揭示大兴安岭中南段铜多金属成矿规律奠定基础.     

江西银山Cu─Au多金属矿床成矿作用的新认识及其找矿意义

本文根据银山矿床成矿特征及其与邻区矿床的对比,论证了在该矿新发现的一种成矿作用──构造动力热液成矿作用;提出矿床的火山-岩浆热液成矿作用与石英斑岩岩浆阶段关系更为密切,形成内带为斑岩型Cu-Au矿体和外带为脉型Cu(Au)、CuPbZn、PbZnAg矿体的成矿系列。根据这两种成矿作用的时空关系,指出银山矿床是构造动力作用热液与火山-岩浆热液双重耦合成矿作用的产物,这一新的认识对指导找矿具有重要意义。     

西南某汞矿带构造体系及其对汞矿的控制

本文仅就西南某汞矿带南段构造体系作一初步分析,进而说明构造体系对汞矿分布的控制,并探讨该区汞矿找矿方面的一些问题。     

中国大地构造单元新格局——从岩石圈角度的思考

以中国大陆的岩石圈岩石学结构模型和根据岩石圈动力学性质划分的克拉通型、造山带型、裂谷型、边缘海洋壳型和岛弧型5大岩石圈类型为基础,结合现今中国大陆西部挤压、东部拉张伸展的特点,提出以四川盆地、鄂尔多斯盆地和银川盆地西边界的岩石圈不连续为界,把中国大陆分为东部和西部2个一级构造单元;不同类型岩石圈为其二级构造单元,一些造山带型岩石圈的亚类为三级构造单元,并结合地质历史,简要讨论了其形成过程及其意义。     

Geological Anomaly of China

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中国东北地区赋煤构造单元与控煤特征

中国东北地区赋煤构造是在太平洋地球动力学体系影响下形成的一系列NE—NNE向断陷盆地,目前对本区赋煤构造单元划分尚未形成统一认识。根据东北地区含煤岩系赋存特征,将东北赋煤构造单元划分为三级体系,即:东北赋煤构造区—3个赋煤构造亚区—11个赋煤构造带。以地球动力学理论为基础,以构造控煤特征为研究主线,探讨了三级赋煤构造单元的基本控煤特征。该项研究对煤炭资源评价和勘查具有重要意义。      

青藏高原东部成矿带地球物理特征分析

本文应用板块构造理论解释高原东部磁场特征,指出本区存在五个不同特征的成矿带(区),它们依次为:康滇裂谷成矿带;龙门山古岛孤成矿带;雅鲁藏布江古洋脊成矿带;金沙江—哀牢山陆块离合成矿带;巴颜喀拉—雅砻江新生陆壳成矿区。其中,康滇裂谷带矿藏十分独特丰富,蕴藏着具世界规模的钒钛镍铂等矿、金铜铅锌矿、稀土及锡等多金属矿,此外,煤、磷、膏、盐及油气资源也十分丰富,是我国矿产资源储量最大、种类最多的一条成矿带。雅鲁藏布江带实际上是世界著名的地中海铬铁矿带主带的东延地段,是我国铬矿资源最有远景的地带。金沙江—哀牢山带是一条构造特殊、蕴藏着多类有色及贵金属的成矿带,如,含金富银多金属矿及斑岩铜矿等,矿化露头常常连绵数百公里,显示了它的巨大经济价值。文章最后对高原成矿带矿化模型及地球物理普查找矿效果进行了讨论,并建议在七条重要的矿带(区)普查矿产资源。