花岗岩残积土中人工挖孔桩流泥施工病害及防治   总被引：3，自引：0，他引：3  

黄力平  李荣强 《地质灾害与环境保护》1998,9(4):59-62

探讨龙岗岩残积土中人工挖孔桩的流泥施工病害产生机制,模拟模型及防治措施,并介绍一个典型的工程实例。  相似文献   

Interaction of rock and atmosphere: patinas on Mediterranean monuments   总被引：2，自引：0，他引：2  

M. Garcia-Vallès  M. Vendrell-Saz  J. Molera  F. Blazquez 《Environmental Geology》1998,36(1-2):137-149

 This paper analyzes – chemically, mineralogically, and petrolographically – the patinas developed on several Mediterranean monuments made with different stones (siliceous and carbonatic) in order to establish their origin and their evolution under the present environmental conditions, and to evaluate the environmental parameters controling their development. Most of the patinas show a common sequence of layers, which, from the outer to the inner zone, are: (1) present bioactivity and/or biological remains, (2) gypsum-rich patina, and (3) calcitic brown to orange patina. Each one may exhibit different fabrics (from micritic to stromatolitic) and may be more or less continuous and homogeneous. The main mineral components are calcite and gypsum, but Ca-oxalates and Ca-phosphates have also been found associated to biological structures, as well as quartz and clays. The different fabrics and textures have been interpreted as consequence of changes in the environmental conditions which seem to be related to the biological activity, facilitating the growth of different organisms and leading to the development of a deposit with distinct characteristics (fabric, texture, porosity, etc.). The gypsum-rich patina has been interpreted as a sulphation of the underlying calcitic layer by the action of atmospheric pollutants or as dry or wet deposition from the atmospheric dust. The mineralogy and texture of the patina is independent of the nature of the underlying rock and only in few cases a micritization process has been observed as interaction between patina and rock. Recently, the penetration of endolithic microflora produced drillings and the development of a fissuration system parallel to the surface, and thus the detachment of the crust from the rock and even flackening of the rock itself has been observed. Consequently, under the present climatic conditions in the Mediterranean basin, erosion is a more active process than deposition, and the crusts and patinas show a tendency to disappear from the surface of the monuments. Received: 3 November 1996 · Accepted: 10 September 1997  相似文献   

苏州花岗岩中钽矿化机理的研究     

聂桂平 《江苏地质》1998,22(1):23-26

苏州花岗岩岩体中稀有元素含量远高于克拉克值,在岩体中Ｔａ／Ｎｂ比值从下向上逐渐升高,边缘相中Ｔａ含量要比内部相高出４～５倍,氧同位素分析表明边缘相样品δ１８Ｏ的亏损是受到雨水交换作用的强烈影响。综合考察苏州花岗岩边缘相的雨水交换与富集稀有元素的岩浆体系之间的关系,可以认为苏州花岗岩在演化结晶至晚期时,在顶部和边缘与雨水热液作用,导致岩浆物理化学条件改变,使稀有元素络合物发生解体,从而发生Ｔａ矿化作用。  相似文献   

内蒙古额仁陶勒盖花岗岩成因与银矿床的形成   总被引：2，自引：0，他引：2  

陈祥  李鹤年 《矿产与地质》1997,11(2):91-98

对额仁陶勒盖花岗岩的地质学、地球化学的研究表明，它为岩浆成因，是壳幔混合源岩浆演化的产物；岩体在成岩过程中发生了强烈的结晶分异作用，导致岩浆后期及期后热液中银的富集，银矿床与石英斑岩（花岗岩结晶分异的产物）在地质及地球化学诸多方面存在着显著的成因联系。  相似文献   

花岗岩岩相学特征及岩石可锯性研究     

梁磊 《矿产与地质》1996,10(3):198-200

花岗岩岩石中矿物的成分、结构、构造类型和矿物力学性质是制约岩石可锯性的主要因素。花岗岩岩石中石英矿物多（岩石偏酸性）、颗粒结晶粗大，矿物裂理和解理发育差，岩石呈致密块状构造，则可锯性差，反之则可锯性好。并以四川红系列花岗岩石材加工为例，说明了花岗岩岩相学特征对岩石可锯性影响的程度。从而，为花岗岩石材开发过程中，如何选择金刚石锯片提供科学参考资料  相似文献   

新疆阿拉套山花岗岩类高ε_Nd值的成因探讨   总被引：13，自引：0，他引：13       下载免费PDF全文

周泰禧  陈江峰 《地质科学》1996,31(1):71-79

新疆阿拉套山广泛出露的华力西期花岗岩类的一般岩石学和地球化学性质可与我国以及世界上大部分地区出露的花岗岩相类比,但其ε_Nd(t)高,为+2.2-+3.2,其中一部分花岗岩的⁸⁷Sr/⁸⁶Sr(t)也高,可达0.715.这可能是壳幔物质AFC式混合的结果,也可能是准噶尔地块及其两缘特殊地质环境的反映。  相似文献   

滇西北鲁甸花岗岩的特征   总被引：2，自引：1，他引：2  

罗万林  尹怀模 《岩石学报》1988,4(2)

鲁甸花岗岩侵位于上三叠统崔依比组,又被上三叠统石钟山组不整合覆盖,为印支期花岗岩。主要由黑云母二长花岗岩和角闪黑云母二长花岗岩组成,边缘相有少量黑云斜长花岗岩出露。副矿物以磁铁矿为主。多数含有标准矿物刚玉。它是介于Ⅰ型和S型之间的一种花岗岩类型,大体相当于加里东型岩体。  相似文献   

腾冲新岐花岗岩岩石学特征     

白嘉芬 《岩石学报》1987,3(3)

新岐花岗岩可分为细粒花岗岩、似斑状花岗岩、中粒铁锂云母花岗岩和蚀变二长岩四类。在化学成分上这些岩石富硅、富氟、富钾,而贫钛、铁、钙,镁,属于铝过饱和系列。主化学成分、微量元素特征、钾长石的三斜度、锶同位素初始比值表明本区花岗岩的成因类型属改造型(或S型)。伴生矿产有Sn、W、Nb、Ta、Li、Rb、Cs和TR等。  相似文献   

强力侵位花岗岩体与金矿的关系——以丹东三股流岩体为例     

吕贻峰  李江风  张鸣 《国土资源》1993,(2)

辽宁丹东五龙金矿、四道沟金矿位于五龙背—大堡花岗岩体与三股流花岗岩体之间,成矿作用与三股流岩体密切。据分析,这两个岩体的岩浆来源相同,岩石化学性质相似,岩体侵位时间相当,且同处于丹东北东向韧性剪切带内,但由于岩体侵位时受控的局部构造环境不同,导致岩体以不同的方式侵位。三股流岩体在韧性推覆剪切带发展演化过程中沿剪切面理以气球膨胀式强力侵位;而五龙背—大堡岩体则是沿该剪切带晚期发育的北西向脆性张裂面被动侵位。不同方式侵位的岩体具有不同的成岩环境,从而在一定程度上控制岩浆气水溶液的分离和聚集。强力侵位的花岗岩体在成岩过程中具有较好的封闭条件,因此可能有利于成矿热液的分泌、聚集和保存,而被动侵位的花岗岩体则不具备这种有利的成矿条件。  相似文献   

Immiscible phases of magmatic fluid and their relation to Be and Mo mineralization at the Yermakovka F–Be deposit, Transbaikalia, Russia     

F. G. Reyf   《Chemical Geology》2004,210(1-4):49-71

Melt and fluid inclusions in minerals from the peralkaline granite intrusion and associated mineralized country rocks from the Yermakovka F–Be deposit were studied to characterize the behaviour of trace elements and exsolved fluids in the transition from magmatic to hydrothermal processes. Ore mineralization was mostly due to volatile release from a deep-seated pluton for which crystallization history and fluid exsolution can be tracked by three batches of magma (Gr1→Gr3) intruded at the level of the ore deposition to form the Yermakovka stock. Each batch of the sequential granite group is found to intrude at decreasing temperature (from 840 to 730 °C) and progressively increasing extent of crystallization of magma in the parental pluton. This resulted in the enrichment of the ascending melts in H₂O (3.9 to 6.1 wt.%), F (2.6 to 4.1 wt.%) and some incompatible elements (Zr, Nb, Th, Rb, Pb). Although the earliest evidence for the exsolution of homogeneous fluoride–sulphate brine correlates with the final stage of the Gr2 ascent, the most intensive volatile(s) release from the emplaced magmas is shown to occur during their in situ crystallization, which was associated with the separation of exsolved fluid into immiscible phases, brine and low-salinity solution. Compositions of these fluid phases are determined using atomic emission spectroscopy of the appropriate fluid inclusions opened by a laser microprobe and EMPA and SEM–EDS analyses of daughter crystals. The brine phase is enriched in Mo, Mn, Be (up to 17, 8, and 0.3 g/kg, respectively) and contains perceptible abundances of Ce, La, Pb, Zn, whereas the low-salinity phase is enriched only in Be (up to 0.6 g/kg). The selective mobilization of the metals from the melt into fluids is considered to result from the oxidized state of the melt and fluids, peralkalinity of the melt during crystallization, and high F content of the melt. The immiscible fluid phases are shown to migrate together through the solidifying stock giving rise to the albitized granite that is enriched in molybdenite but devoid of Be minerals. In the country rocks, solutions similar to the brine and low-salinity phases of the magmatic fluid made up separate fluid flows, which produced Be and Mo mineralization and were issued predominantly from the parental pluton. Both types of mineralization are nearly monometallic which suggests that of the metals, jointly transported by the brine, only Mo and, in part, Ce and La precipitated separately at the level where the low-salinity solutions deposited Be ores.  相似文献