川西攀枝花—西昌地区结晶基底的划分   总被引：7，自引：0，他引：7  

马玉孝王大可  纪相田阚泽忠张成江  周美夫 《地质通报》2003,22(9):688-694

长期以来，由于同位素年龄依据不足和没有正确区分晚二叠世热接触变质岩、喜马拉雅期动力变质岩与前震旦纪区域变质岩，攀西地区结晶基底的划分存在许多困难和问题。本文依据1：50000区域地质调查结果，将原仁和群(Pt1R)修改为晚二叠世岩浆岩和喜马拉雅期动力变质岩，将五马箐(岩)组(Pt1w)和顶针杂岩(Pt1D)修改为晚二叠世热接触变质岩和喜马拉雅期动力变质岩，将安宁村组(Ptlα)和纸房沟组(Pt1z)修改为震旦系地层，并依据岩石学、岩石化学和微量元素地球化学特征，将结晶基底划分为变质侵入体、变质表壳岩和TTG套岩，论述了结晶基底的成因和演化。  相似文献   

几种常见矿物的接触角测定及其讨论   总被引：4，自引：0，他引：4       下载免费PDF全文

陆现彩  侯庆锋尹琳赵连泽  刘显东 《岩石矿物学杂志》2003,22(4):397-400

为了评价矿物表面与特征液体的界面能量，分别测定了长石、石英、黑云母、方解石、萤石和黄铁矿等7种常见矿物与水、正庚烷和正丁醇的接触角，并计算了相应的表面自由能。结果表明同一矿物不同结晶面(晶面)的接触角有一定的差异，这一差异与矿物结构面上原子种类和相对含量差异有一定的对应关系。  相似文献   

鲁东官山榴辉岩与围岩接触关系的新发现及其对年代学的启示   总被引：14，自引：2，他引：14       下载免费PDF全文

宋明春  金振民  王来明  张希道  李远友 《地质学报》2003,77(2):238-244

鲁东官山榴辉岩呈透镜状包于变质含霓石碱性花岗岩中,榴辉岩的片麻理与主岩片麻理总体呈交切关系,局部可见变质含霓石碱性花岗岩呈细小岩枝状脉贯入榴辉岩中。变质含霓石碱性花岗岩锆石U-Pb法下交点年龄为231±25 Ma,上交点年龄为818±66 Ma。发现了闪长玢岩脉斜切式侵入榴辉岩及变质含霓石碱性花岗岩的接触关系,且闪长玢岩脉中有榴辉岩捕虏体,这种现象指示:闪长玢岩侵位时榴辉岩已折返至地壳较浅部位。研究表明,榴辉岩与变质含霓石碱性花岗岩共同经历了新元古代的超高压变质作用,但变质作用发生时含霓石碱性花岗岩可能处于熔融状态,榴辉岩是其中的固相包体。  相似文献   

Yixunite and Damiaoite—A Twin of New Native Alloys of Indium and Platinum from the Yanshan Mountains     

Yu ZuxiangInstitute of Geology  Chinese Academy of Geological Sciences  Baiwanzhuan  Beijing 《《地质学报》英文版》1997,71(4):480-485

Yixunite and damiaoite Were found in a cobalt- and copper-bearing platinum ore vein of a contact metasomatic deposit. The chief ore minerals are bornite, chalcopyrite, magnetite and carrollite. The platinum minerals include moncheite, sperrylite, daomanite, cobalt malanite and cooperite. Yixunite and damiaoite occur as immiscible globules, 1.0 to 2.0 mm in diameter. Yixunite is always in the central part of a globule. It is opaque with metallic lustre, bright white colour and black streak. HM = 5.8; VHN50 = 634 kg/mm2 (573-681 kg/ mm2); insoluble in HCl, HNO3, HF or H3PO4; no cleavage; no magnetism. Density is hard to measure because of small grain size. Calculated density = 18.21 g/cm3. Reflective colour is bright white with a yellowish tint. Isotropic. The mean analytical results (ranges) (%) are: Pt 82.8 (81.8-83.6), In 16.4(15.6-17.1) and total 99.2. The empirical formula (based on 4 atoms) is Pt2.993 In1.007 . The five strongest lines of X-ray diffraction (hkl, d,I) are 111, 2.30 (100); 200, 1.99 (  相似文献   

Statistical Detection and Characterization of a Deviation from the Gutenberg-Richter Distribution above Magnitude 8     

V. F. Pisarenko  D. Sornette 《Pure and Applied Geophysics》2004,161(4):839-864

— We present a quantitative statistical test for the presence of a crossover c₀ in the Gutenberg-Richter distribution of earthquake seismic moments, separating the usual power-law regime for seismic moments less than c₀ from another faster decaying regime beyond c₀. Our method is based on the transformation of the ordered sample of seismic moments into a series with uniform distribution under condition of no crossover. A simulation method allows us to estimate the statistical significance of the null hypothesis H₀ of an absence of crossover (c₀=infinity). When H₀ is rejected, we estimate the crossover c₀ using two different competing models for the second regime beyond c₀ and the simulation method. For the catalog obtained by aggregating 14 subduction zones of the Circum-Pacific Seismic Belt, our estimate of the crossover point is log(c₀)=28.14 ± 0.40 (c₀ in dyne-cm), corresponding to a crossover magnitude m_W=8.1 ± 0.3. For separate subduction zones, the corresponding estimates are substantially more uncertain, so that the null hypothesis of an identical crossover for all subduction zones cannot be rejected. Such a large value of the crossover magnitude makes it difficult to associate it directly with a seismogenic thickness as proposed by many different authors. Our measure of c₀ may substantiate the concept that the localization of strong shear deformation could propagate significantly in the lower crust and upper mantle, thus increasing the effective size beyond which one should expect a change of regime.  相似文献   

山东莒南-日照地区榴辉岩与围岩的接触关系及其地质意义   总被引：1，自引：2，他引：1  

宋明春  金振民  赵庆龄  段京文 《矿物岩石》2004,24(2):1-5

对山东莒南日照地区榴辉岩与不同围岩的接触关系进行研究发现：包裹榴辉岩的斜长角闪岩有窄的细粒边；榴辉岩在变质地层及超镁铁岩中呈夹层状产出，与超镁铁岩相伴产出的榴辉岩有角闪石化边；变质含霓石花岗岩及闪长玢岩侵入榴辉岩。认为榴辉岩是“就地的”．其原岩类型较复杂。其形成时代可能为新元古代。  相似文献   

列车荷载对平行换乘地铁车站深基坑变形影响   总被引：1，自引：0，他引：1  

高伟君  姚燕明  蔚俊霞 《岩土力学》2004,25(Z2):375-378

根据地铁车站轨道结构的特点,利用集总参数法建立了轮轨竖向耦合振动模型;分析了新建地铁车站深基坑开挖过程中既有车站内的轮轨接触荷载对车站结构及其周围土层变形的影响.通过计算分析认为,列车荷载引起的结构变形在允许值的7 %范围以内,引起的地面沉降在允许值的3 %范围以内.  相似文献   

金丽温高速公路K81高边坡变形动态数值分析     

汪会帮  陆锡铭  吕庆  许建聪 《岩土力学》2004,25(Z2):479-481

对金丽温高速公路K81高边坡进行接触大变形有限元动态数值分析.结果表明,路堑边坡开挖,导致滑面的法向应力减小、抗滑力下降,是引起古滑坡复活的根本原因.研究结果也说明了接触大变形有限元分析方法可以较好地分析潜在滑面的力学作用,是研究滑坡的滑动机理的有效方法.  相似文献   

Grain coarsening in contact metamorphic carbonates: effects of second-phase particles, fluid flow and thermal perturbations   总被引：3，自引：0，他引：3  

A. Berger  M. Herwegh 《Journal of Metamorphic Geology》2004,22(5):459-474

Under contact metamorphic conditions, carbonate rocks in the direct vicinity of the Adamello pluton reflect a temperature‐induced grain coarsening. Despite this large‐scale trend, a considerable grain size scatter occurs on the outcrop‐scale indicating local influence of second‐order effects such as thermal perturbations, fluid flow and second‐phase particles. Second‐phase particles, whose sizes range from nano‐ to the micron‐scale, induce the most pronounced data scatter resulting in grain sizes too small by up to a factor of 10, compared with theoretical grain growth in a pure system. Such values are restricted to relatively impure samples consisting of up to 10 vol.% micron‐scale second‐phase particles, or to samples containing a large number of nano‐scale particles. The obtained data set suggests that the second phases induce a temperature‐controlled reduction on calcite grain growth. The mean calcite grain size can therefore be expressed in the form D = C₂ e^Q*/RT(d_p/f_p)^m*, where C₂ is a constant, Q* is an activation energy, T the temperature and m* the exponent of the ratio d_p/f_p, i.e. of the average size of the second phases divided by their volume fraction. However, more data are needed to obtain reliable values for C₂ and Q*. Besides variations in the average grain size, the presence of second‐phase particles generates crystal size distribution (CSD) shapes characterized by lognormal distributions, which differ from the Gaussian‐type distributions of the pure samples. In contrast, fluid‐enhanced grain growth does not change the shape of the CSDs, but due to enhanced transport properties, the average grain sizes increase by a factor of 2 and the variance of the distribution increases. Stable δ¹⁸O and δ¹³C isotope ratios in fluid‐affected zones only deviate slightly from the host rock values, suggesting low fluid/rock ratios. Grain growth modelling indicates that the fluid‐induced grain size variations can develop within several ka. As inferred from a combination of thermal and grain growth modelling, dykes with widths of up to 1 m have only a restricted influence on grain size deviations smaller than a factor of 1.1. To summarize, considerable grain size variations of up to one order of magnitude can locally result from second‐order effects. Such effects require special attention when comparing experimentally derived grain growth kinetics with field studies.  相似文献   

Field and petrological evidence for a Late Palaeozoic (Upper Carboniferous–Permian) age of the Erfaulet orthogneiss (Gran Paradiso,western Alps)     

Benjamin Le Bayon  Michel Ballèvre 《Comptes Rendus Geoscience》2004,336(12):1079-1089

In the Gran Paradiso massif (western Alps), the boundary between the Erfaulet orthogneiss and the overlying metasediments (Money Complex) is interpreted as a Late Palaeozoic intrusive contact. Major arguments in favour of this hypothesis are: (i) the obliquity of the sedimentary layering with respect to the contact; (ii) the presence of aplitic dykes within the Money Complex; (iii) the lack of a mylonitic zone; and (iv) rare relics of an early generation of garnet in the Money metasediments, interpreted as evidence of the contact metamorphism of the Erfaulet granite. To cite this article: B. Le Bayon, M. Ballèvre, C. R. Geoscience 336 (2004).  相似文献