河北小石门银金矿床地质地球化学特征与矿床成因

河北小石门银金矿床位于小寺沟斑岩铜钼矿床的南西侧.矿体呈脉状、透镜状,银金矿化受NNE向断裂控制,成矿与杂岩体及二长斑岩有关;矿物组合主要为中低温矿物组合,成矿温度240～365℃;流体包裹体研究表明成矿流体富硫,有较高的K ,NH4 ,Ca2 和Na ,成矿热液为岩浆热液;硫同位素分析显示,硫来源于岩浆;稀土元素分析亦表明成矿物质来自于二长斑岩及小寺沟岩体,而铅锌矿可能部分来源于地层.推断小石门银金矿床为中低温热液矿床.     

冀东迁西—迁安地区紫苏花岗岩的地球化学特征及其成因

本文根据地质和地球化学的研究提出本区紫苏花岗岩主要是由英云闪长质、花岗闪长质岩浆侵位之后经麻粒岩相变质而形成的。根据地球化学特征,本区的紫苏花岗岩可分为大离子亲石元素亏损的北区(太平寨—三屯营)和大离子亲石元素较富集的南区(水厂—松汀),它们的地球化学差异反映了其形成时构造条件的不同。     

Alpine olivine- and titanian clinohumite-bearing assemblages in the Erro-Tobbio peridotite (Voltri Massif, NW Italy)

The microstructures in the Erro-Tobbio peridotite indicate several stages of recrystallization of olivine + titanian clinohumite-bearing assemblages. The development of these assemblages is closely associated with serpentinite mylonites, in which they occur in shear bands and foliations and are inferred to have grown synkinematically, in veins, and as post-kinematic radial aggregates. In the peridotite wall-rock adjacent to these mylonites, the same assemblages have recrystallized statically at the expense of original olivine and pyroxenes, mesh-textured chrysolite and antigorite veins. In addition, the olivine-bearing assemblage occurs in widespread vein systems. The brittle deformation of the peridotite resulting in the development of these vein systems is closely related to ductile deformation of metagabbroic dykes in the peridotite. Although early metasomatism resulted in extensive rodingitization of the gabbros, some dykes show an eclogitic assemblage of Na-clinopyroxene + garnet + chloritoid + chlorite ± talc. These observations, the microstructures and the mineral chemistry all suggest that the assemblages in the ultramafic rocks and metagabbros developed during a prograde evolution towards high pressures (>13–16 kbar, 450–550° C), and during subsequent decompression. This metamorphic evolution is considered to be related to Late Cretaceous intraoceanic subduction in the Alps-Apennine system and closure of the Piedmont-Ligurian basin.     

冀东太平寨地区斜方辉石的地质特征和成因研究

冀东太平寨地区太古宙麻粒岩相变质杂岩中,含有岩浆成因和变质成因的两类斜方辉石,后者又可分为早、晚两期。在地质产状研究的基础上,据岩相学、矿物化学成分和温度、压力条件,阐明了斜方辉石的成因。研究结果为该区划分地质事件和探索早期地壳演化历史提供了重要的依据。     

马17井映震灵敏的应力条件数学模拟研究

本文利用线弹性理论的二维有限元方法,计算了马17井的区域应力及井区平面与剖面的应力状态,研究该井映震灵敏的应力条件。计算结果表明井区在华北地区中强以上地震活动时具有一定的应力集中     

冀东陆壳结构的岩石学模型

冀东地区的古老变质岩系是一个出露的大陆地壳断面。根据变质岩系的变质相、亚相的研究和地质温压计计算的结果推定的深度,并结合地球物理测深资料,以及笔者测定和前人的岩石高压下波速实验资料提出了本区大陆地壳结构的岩石学模型。下地壳由麻粒岩相岩石组成,上部为角闪石麻粒岩亚相的中性成分的麻粒岩,下部为辉石麻粒岩亚相的基性成分的麻粒岩构成,底部夹有透镜状蛇纹石化橄榄岩以及紫苏花岗岩。中地壳主要由高角闪岩相的中性-中酸性成分的片麻岩、片岩构成,顶部为低角闪岩相的片麻岩、片岩,广泛发育英云闪长岩和花岗闪长岩岩体,含隙间高温流体相(fluid phase),形成高导-低速层。上地壳主要为绿片岩相(部分低角闪岩相)的板岩、千枚岩、片岩、变粒岩以及花岗岩组成,顶部为沉积盖层     

冀北坝上地区深部地质构造特征及其对火山活动和铀成矿的控制作用

冀北坝上地区位于华北地台北缘。其深部地质构造有两个显著特征：一是全区性的莫霍面下拗，地壳增厚；二是软流圈部分伸入到下岩石图上部，造成局部地区地幔上隆，地壳减薄。火山喷发形成的沽源火山盆地和大滩火山盆地与两个地幔上隆，地壳减薄区，上下相互对应。铀矿床（点）沿地幔隆起周边构造活动带规律性分布。上述两事实有力地证明了深部地质构造对中新生代火山活动和铀成矿的控制作用。沿地幔隆起周边构造活动带是今后寻找铀及多金属矿产的有利地段。     

冀中中奥陶统高频率旋回层序的基本特征

通过野外实测剖面及路线观察，河北中部中奥陶统马家沟群的高频率旋回可划分为三个级别，并与层序地层学术语可以对比，由低到高为；六级旋回──韵律层；五级旋回──准层序；四级旋回──准层序组。这些由米兰柯维奇驱动力所控制的旋回层序在不同的沉积环境中具有不同岩石组合特征，反映了高频率旋回的沉积模式。     

Late Ordovician evolution of the intracratonic basins in north-west Gondwana

The Palaeozoic intracratonic basins in northwest Gondwana, i.e. the Amazonas, Parnaiba and Acera basins, probably opened during late Caradoc and Ashgill times. The fluviatile sedimentation later changed to littoral at the basinal margins. A transgression from the north-west region of Gondwana slowly overlapped the margins of the intracratonic basins. The transgression reached its maximum in the Rawtheyan (late Ashgill), as evidenced by fossiliferous shallow marine sediments in the Amazonas Basin. The Hirnantian glaciation in north Gondwana lowered the sea level, and in the Amazonas Basin a littoral sedimentation followed on shallow marine strata. From the opening of the basins onwards, a shallow sea probably existed close to the epicontinental basins in north-west Gondwana. The basins were connected via a narrow passage between the Guayana and Ivorian cratons.