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1.
西藏曲水岩基的Pb、Sr同位素组成及其三元混合成因模式 总被引：7，自引：0，他引：7
本文综合分析了西藏曲水岩基的Pb、Sr同位素组成特征，并运用同位素的混合模式对该岩基的物质来源和成因进行了进一步的深入研究。结果表明，该岩基的Pb、Sr同位素组成较好地符合三元混合模式。结合冈底斯岩带的地质、构造及其他地球化学特征，得出曲水岩基花岗岩类岩石的物质来源包括幔源岩浆、前造山带和上地壳物质三部分。 相似文献
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尼木渐新世黑云母二长花岗岩中含有丰富的形态各异的暗色镁铁质微粒包体。本文报道了寄主岩和镁铁质包体的年代学、元素地球化学及Sr- Nd- Hf同位素组成,据此阐明了岩石的成因,并探讨了岩浆混合作用在成岩中的意义及其对陆壳增生的启示。锆石LA- ICP- MS U- Pb定年结果表明,寄主岩和镁铁质包体的成岩年龄在误差范围内基本一致,均为约30Ma,说明它们同时形成。元素地球化学组成上,寄主黑云母二长花岗岩为高钾钙碱性、准铝质,富集Rb、Th、U等大离子亲石元素,亏损Nb、Ta、Ti、P等高场强元素,且具有高Sr、低Y和Yb含量,Sr/Y比值高,缺乏明显铕负异常,表现出埃达克质岩石的特征。镁铁质包体贫硅,富铁、镁,具有与寄主岩相似的稀土与微量元素分布模式。二者的全岩Sr、Nd同位素和锆石Hf同位素组成也相近\[寄主岩:(87Sr/86Sr)i=0.7057~0.7064,εNd(t)=-1.45~0.35,εHf(t)=1.21~7.34;镁铁质包体:(87Sr/86Sr)i=0.7058~0.7064,εNd(t)=-2.23~-1.57,εHf(t)=2.40~7.04\]。综合分析表明,尼木渐新世黑云母二长花岗岩应主要起源于碰撞加厚的新生镁铁质下地壳的部分熔融,镁铁质包体应为幔源玄武质岩浆与其诱发加厚地壳熔融形成的埃达克质岩浆经不均匀混合作用的产物。结合对冈底斯带岩浆岩已有资料的全面分析,表明幔源玄武质岩浆的底侵及其诱发的岩浆混合作用既是冈底斯岩基形成的主要方式,也是导致青藏高原陆壳增生的重要途径。 相似文献
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青藏高原中新生代花岗岩Sr、Nd同位素研究 总被引：10，自引：2，他引：10
青藏高原中新生代岩浆活动强烈，本文报道青藏高原西部中新生代代表性花岗岩的Sr，Nd同位素测定结果，结合前人已发表的东部地区花岗岩同位素资料，初步探讨了青藏高原地区中新生代花岗岩的Sr，Nd同位素组成、物质来源与成因。研究表明，分布于冈底斯地块北南边界(即冈底斯花岗岩北带和南带)与洋壳俯冲有关的燕山晚期花岗岩，具有低^87Sr／^86Sr初始值(小于0．706)、正εNd(t)值和年轻的t2DM模式年龄的特征，岩浆来源于俯冲洋壳的熔融；与陆-陆碰撞及碰撞后有关的冈底斯花岗岩^87Sr／^86Sr初始值变化大(0．706～0719)，而εNd(t)值和t2DM都在很小范围变化，Sr、Nd同位素组成似乎与时代、岩性无关，说明壳幔混合花岗岩的同位素源区长时期保持相对均一。无洋壳物质参与的通过陆内俯冲作用形成的喜马拉雅区花岗岩，具有高^87Sr/^86Sr初始值(大于0.720)、古老模式t2DM年龄(1792～2206Ma)和低εNd(t)值(-10．3～-16．3)特征，并与基底岩石的Sr，Nd组成一致，岩浆源区为壳源。由此说明花岗岩类及其岩石组合的形成主要取决于深部部分熔融物质的成分，不同火成岩组合的差异反映了青藏高原岩石圈组成和演化的不均一性。 相似文献
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对内蒙古红花尔基白钨矿矿床的赋矿花岗岩进行了全岩Sr、Nd同位素、钾长石Pb同位素以及LA-MC-ICPMS锆石Hf同位素特征研究。结果表明,从肉红色二长花岗岩、灰白色二长花岗岩到石英二长岩,它们的(~(87)Sr/~(86)Sr)_i值依次降低,均值分别为0.70525、0.70517和0.70482,_(εNd)(t)值则依次增加,均值分别为+2.2、+2.3和+3.1。2种二长花岗岩的钾长石Pb同位素值较均一,其中~(206)Pb/~(204)Pzb为18.258~18.276,~(207)Pb/~(204)Pb为15.507~15.512;~(208)Pb/~(204)Pb为37.994~38.018。3种花岗岩的锆石Hf同位素特征显示~(εHf)(t)值分别为+5.2~+10.4(均值+8.1)、+3.1~+9.8(均值+7.5)、+5.8~+14.4(均值+9.2)。赋矿花岗岩的Sr-Nd-Pb-Hf同位素特征指示其源岩物质很可能是以新元古代起源于亏损地幔的下地壳物质为主,石英二长岩可能是岩浆混合了少量地幔物质形成的包体。区域构造分析表明,红花尔基白钨矿矿床赋矿花岗岩岩浆源区的形成可能与新元古代古亚洲洋演化过程中俯冲大洋板块与上地幔的相互作用有关;早侏罗世,蒙古—鄂霍次克洋盆在本区闭合后,板块碰撞隆起的挤压环境触发了源岩物质的部分熔融,从而形成了赋矿花岗岩。 相似文献
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本文对Rb—Sr等时线的理论基础提出了疑问,並从理论上对初始Rb—Sr体系中变量~(86)Sr与~(87)Sr/~(86)Sr对等时线正确性的影响进行了讨论。从数学上表明,用~(86)Sr作为公分母可增强Rb—Sr等时图上的线性相关.盐说明只有当初始~(87)Sr/~(86)Sr比值形成—水平线,或者在初始时等时图上就存在线性相关的时候才产生线性排列。在初始值为水平线时,线性排列常可得到正确的等时线而给出真实年龄和体系的初始比,而在初始值为线性相关时可产生异常等时线,它没有明确的地质意义。于是视等时线被用来概括迄今文献中所发表的异常等时线,並因此推导出视等时线方程。文中分别论述了分离结晶作用、部分熔融、混合及变质作用对Rb—Sr等时线的影响。可以得出结论,只要初始体系中~(87)Sr/~(86)Sr与~(87)Rb/~(86)Sr间比值满足线性相关,就可得到所观测的Rb—Sr等时线。由于仅根据Rb—Sr同位素数据不能区分正确的等时线与视等时线,因此在解释任何地质体系的Rb—Sr等时线年龄方面必须谨慎。 相似文献
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江苏栖霞山铅锌多金属矿床深部碳-氧-锶同位素地球化学特征及其指示意义 总被引：1，自引：0，他引：1
以栖霞山铅锌多金属矿床深部找矿钻孔岩心为对象,开展碳-氧-锶同位素地球化学研究。结果表明,栖霞山矿床矿石样品δ13CV-PDB同位素值为-5.1‰～1.9‰,且由浅部至深部,矿石样品的δ13C、δ18O值处于增大的趋势,指示成矿流体中的碳起源于碳酸盐岩、源自地幔和岩浆的深源碳。对锶同位素的研究显示,栖霞山矿石~(87)Sr/~(86)Sr值为0.704816～0.71405,部分大于矿体围岩黄龙组灰岩的~(87)Sr/~(86)Sr值(0.708329～0.709685),部分小于矿体围岩黄龙组灰岩的~(87)Sr/~(86)Sr值,并与不同来源的Sr同位素对比,揭示栖霞山矿石中Sr兼具基底地层Sr和幔源Sr的混合来源特征,且在围岩蚀变过程中~(87)Sr/~(86)Sr的变化应主要由成矿流体引起。结合本区成矿地质特征认为,栖霞山矿床成矿流体可能来自花岗岩的期后热液,在热动力作用下,流经元古宇基底地层,形成具有混合物质来源的成矿流体,成矿作用过程主要为成矿流体与围岩碳酸盐岩发生水-岩反应所致。 相似文献
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铲子坪金矿位于雪峰山构造岩浆岩带的白马山复式花岗岩体外接触带附近。本文通过对铲子坪金矿床岩石地球化学以及稳定同位素的研究,探讨其矿床成矿物质来源及矿床成因。研究结果表明:矿石中金属硫化物的δ34S介于-7.58‰~+0.32‰,平均为-2.44‰,富轻硫,表明硫化物中的硫主要来自花岗岩浆,有部分地层硫酸盐中的硫混入;铅同位素组成相对稳定,变化范围很小。根据铅构造模式图解和△γ-△β图解,铅同位素主要来源于地幔,有部分地壳铅的加入;氢、氧同位素表明成矿流体具有变质热液和岩浆热液的双重性,成矿晚期热液有大气水成分加入;碳同位素表明成矿流体与砂质板岩关系密切,与地幔或深部流体有一定的关系,矿床成矿流体中的CO2很可能为壳幔混合;锶同位素研究表明,铲子坪金矿床的(87Sr/86Sr)i组成特征与华南陆壳重熔性花岗岩初始岩浆水的(87Sr/86Sr)i组成特征基本一致,表明其成矿作用可能与岩浆热液有关。铲子坪金矿成因类型为岩浆热液型。 相似文献
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通过矿物流体包裹体Rb-Sr同位素测年,获得鄂北黑龙潭金矿石英Rb-Sr等时线年龄为132.6±2.7Ma,表明该金矿床形成于早白垩世中期。矿石石英中流体包裹体Sr同位素初始比(~(87)Sr/~(86)Sr)i平均值为0.710798,小于陆源硅酸盐的值(0.720),高于地幔Sr的初始值(0.707),暗示成矿物质来源于壳幔混合。结合各类岩矿石Au丰度变化,S、Pb、H、O等同位素组成,以及稀土和微量元素特征、成矿流体等研究,认为该矿床的形成可能与燕山期持续伸展阶段大规模构造-岩浆活动有关,燕山期中酸性岩浆活动为金矿成矿提供了主要矿源和热源。 相似文献
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浙江莫干山花岗岩体锆石U-Pb、全岩Rb-Sr年代学、Sr-Nd-O同位素地球化学及成因研究 总被引：2，自引：0，他引：2
莫干山花岗岩体位于东天目山晚中生代火山盆地东端,用LA-ICPMS进行锆石U-Pb定年得到年龄为128.1±2.1Ma,全岩Rb Sr等时线定年结果为135.4±4.3 Ma,表明其属燕山晚期岩浆活动产物.莫干山花岗岩的Sr-Nd-O同位素分析结果为:初始87Sr/86Sr=0.70933;εNd(t)=-3.75～ - 6.4;δ18O=8.86‰～10.78‰,表明其成因类型属Ⅰ型花岗岩,是壳-幔物质混合形成的.按Sr Nd双变量二元混合模型计算得出源区物质中地壳端员和亏损地幔端员的贡献份额分别为47％～49％、51％～53％.莫干山花岗岩与建德群黄尖组火山岩的锆石U-Pb年龄、全岩Rb Sr等时线年龄基本一致,其Nd-Sr同位素组成也很相似,表明它们来自同一岩浆源. 相似文献
11.
区域蒸散发量的气候学计算方法 总被引：6，自引：0，他引：6
本文介绍了一种计算区域蒸散发量的气候学方法。本法应用Ｂｏｕｃｈｅｔ区域蒸散发互补关系概念，以陕西省５５个流域或区间的常规地面气候观测资料为基本输入，建立了区域蒸散发互补关系模型。该模型具有计算成果合理，精度较高，适应性广等特点。 相似文献
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区域崩塌滑坡的易发性评价--以四川省珙县为例 总被引：4，自引：0，他引：4
以四川省珙县为例，探讨了以GIS技术为支撑的区域崩塌、滑坡易发性评价的基本思路和技术路线；对评价指标的选取作了概括的分析和说明，认为其预测评价因素分为基本因素和诱发因素2大类；采用模糊综合评判方法对崩塌、滑坡的易发性进行评价，并在模糊综合评判方法的具体应用、评价指标隶属度的确定以及权重确定等方面也作了分析和阐述；对珙县区域崩塌、滑坡的易发程度讲行了评价，结果与实际较为吻合。 相似文献
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人文因素与自然因素的耦合是人地关系探讨中的一个热点和难点问题. 基于行政单元获取的人文因素存在着诸多缺陷, 与基于自然单元获取的自然要素的耦合存在着困难. 人文因素空间化是解决二者耦合研究的一种有效途径, 提出从IPAT(IPACT)模型出发识别可空间化的人文因素, 从面插值与统计建模两个方面对空间化方法进行了梳理, 对比分析了各种方法的优缺点及其适用领域, 并提出今后人文因素空间化研究的主要方向. 相似文献
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The achievements of the mineral industry of Israel and an overall reconnaissance of the natural resources endowment of the country have been evaluated by the areal value estimation method, using the COMOD software package. In broad terms, the evaluation relies on geological variables obtained from quantifying the geological map of a region and on cumulative past production records, which, when prorated per unit area, yield a series of unit regional values (u.r.v.)measurements for individual commodities, resource sectors, and total resources. The two groups of variables facilitate conducting comparisons with other well-developed and/or geologically similar regions from which the future potential of the region, with respect to both overall endowment and individual commodities, can be assessed. The model underlying this appraisal method assumes that all regions above a size of about 5,000 sq kms are equally valuable with respect to total endowment in natural resources, regardless of inherent geological characteristics. To date, several areal value estimation studies have been carried out for 11 different countries, encompassing a total of 111 politically-administratively defined regions. These studies provide an adequate information base for between-region comparisons. The individual states of the United States, constituting what can be regarded as well-developed regions, may serve as an expectation for all such comparisons. The distribution of the u.r.v. of total resources of the individual states is lognormal with a geometric mean of 54,954 1967 U.S. dollars per square kilometer. Based on the above assumption, this value can serve as a conservative estimate for the total output any region can be expected to produce. Thirty different mineral commodities are known to exist in Israel. Of these, 19 are economically exploited and the remaining 11 are at present uneconomical mineral occurrences. Past production records have been obtained and assembled for 14 of the exploited commodities. From these records, a number of statistics were computed to evaluate the development of the mineral industry of the country and its future potential. In absolute figures, the overall cumulative production has been rather small, amounting to only 1,679.8 million deflated 1967 U.S. dollars (equivalent to 2,082 million current U.S. dollars or 10,260 million current Israeli pounds). Only bromine, potash, and phosphate are of worldwide significance, amounting respectively to 10, 2.9, and 1 percent of the world production in 1977. Construction materials, with the longest production history, have been the most valuable, accounting for 53.6 percent of the total cumulative output. They are followed by nonmetals (34.7 percent),metals (8 percent)and fuels (3.7 percent).The value-ranking of individual commodities and their respective contribution to the total cumulative output is: cement, 35 percent; potash, 19 percent; stone, 15 percent; phosphate, 11 percent; copper, 8 percent; sand and gravel, 4 percent; bromine, 3 percent; petroleum, 2.5 percent; natural gas, 1 percent; periclase, 0.7 percent; salt, 0.4 percent; and glass sand, 0.2 percent. Total annual output for the period 1948–1977 exhibited a constant growth with no indication of approaching a plateau of diminishing returns. As new commodities became exploited, the share of constructional materials in the total output gradually declined from 100 percent in 1948 to 45 percent in 1977. The contribution of the mineral industry to the annual gross national product rose steadily from 0.55 percent in 1951 to 2.2 percent in 1964. Thereafter, it fluctuated around an average of about 1.8 percent. Total output and production of constructional materials correlate very highly with both gross national product (GNP)and population size. However, when only the annual changes in these variables are considered, the correlation coefficients are found to be insignificant. The u.r.v. of Israel (with an area of 20,700 sq kms and a population of 3,653,000)is 81,154 deflated 1967 U.S. dollars per sq km. It exceeds the expected value for well-developed regions. It can therefore be concluded that Israel is not exceptionally poor in natural resources, as is commonly felt. On the other hand, its high u.r.v. also implies (unfortunately)that the development potential of its mineral industry is rather limited. The u.r.v. estimates, which are based on area alone, can be refined to some degree by considering the geological characteristics of the investigated area. The geological composition of the country was quantified by point counting the geological map, using a grid network of 40.3 sq km cells. Each map unit was assigned to one of 65 standard time-petrographic units. This sampling density results in the recognition of 11 time-petrographic units (instead of 15, which are actually present).Based on linear statistical association between mineral resource diversity and geological diversity established for the states of the United States, Israel can be expected to possess 31 different commodities. Since only 19 have thus far been exploited, Israel can be expected to produce 12 additional commodities. The identity of these missing resources can be inferred by examining the inventory of commodities produced in other regions with a similar geological framework and by evaluating the potential of the 11 noneconomical mineral occurrences, which have already been discovered in the country. The geology of Israel was compared to 12 other regions; of these Egypt, Libya, Sudan, and Sinai were found to be most similar to Israel, each having 8 or 9 time-petrographic rock types in common with Israel, 7 of which are identical. Based on these comparisons and on additional information from other sources, it appears that the commodities that are more likely to be produced in the foreseeable future include manganese, feldspar, uranium (from phosphates),lignite, oil shale, and iron. The mineral industry of Israel accomplished quite significant achievements in the course of its modern history of only 35 years. These resulted from concerted national exploration and development efforts, which were supported by massive governmental capital investments. The areal value method of mineral resources appraisal is based on a cybernetic black box system model in which the degree of commitment derived from the socioeconomic infrastructure is viewed as the driving agent in converting the inherited geological characteristics of the region into economic marketable mineral commodities. The case history of Israel provides a strong substantiation for this generalized system model. 相似文献
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举例对矿产资源勘查区块的划分及编号方法进行了介绍.并按纬度差10′的间隔,计算出了安徽省不同纬度上基本单位区块、四分之一区块和小区块的面积,为在全省境内实施的矿产资源勘查项目的勘查面积计算提出了统一标准. 相似文献
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基于中国自动气象站与CMORPH降水产品融合的0.1°×0.1°高分辨率逐时降水量网格数据集以及气象站点日降水的实测资料,对青藏高原面雨量的空间分布做了研究,并运用线性分析法对青藏高原季节面雨量和逐时面雨量的年际变化做了分析。结果表明：（1）0.1°×0.1°高分辨率格点降水数据能够准确地反映青藏高原面雨量的空间分布特征,东南缘的降雨量远大于西北部。格点数据与站点数据之间偏差率小于20%的站点占到站点总数（84个）的65.48%,相关系数大于0.9的站点有48个。（2）2008-2013年青藏高原总面雨量的年均值为133.42×1010 m3,夏季面雨量最大,占到全年面雨量的51.48%。四季面雨量均呈增长趋势,春、夏、秋、冬的线性倾向率分别为0.40×1010 m3·a-1、3.11×1010 m3·a-1、1.30×1010 m3·a-1和0.92×1010 m3·a-1。（3）面雨量峰值出现在19：00-20：00（北京时间,下同）,面雨量增多的时间出现在17：00-02：00。 相似文献
17.
面金属量法是一种基于地球化学分析数据的资源量定量估算方法,该方法的应用主要局限于在数据层面上,结果只能反映数据异常本身的特点,而不是控制异常性质的地质条件。为解决这一局限性,文章引入相似系数的概念,相似系数的计算原理是将控矿地质因素数值化,从而转换成数据模型,通过某种数学算法与已知的模型区相类比,得出一个表示与模型区相似程度的数值,再用此相似系数对面金属量法估算的资源量进行校正,从而间接地实现控矿地质条件对定量预测结果的控制。该方法实现了纯数据驱动与智能驱动的有效结合,使得该定量方法更具科学性,同时增加了定量预测结果的可信度。从试验结果看,改进后方法的定量预测结果更加合理,具有实用价值。 相似文献
18.
B. Chattopadhyay 《Mathematical Geology》1990,22(5):589-598
The Main Hill Arkasani Granophyre Pluton (MAG), a product of Proterozoic intraplate acid magmatic activity, represents an anatectic melt of the enveloping rocks of dominantly pelitic composition with subordinate trondhjemitic gneiss and basic rocks. Petrography, chemistry, correlation between compositional attributes, areal variation of volume percent granophyric intergrowth, and varimax rotated factor analysis of compositional attributes of these rocks suggest that in the MAG pluton, plagioclase phenocrysts and biotite crystallized first, followed by change of level of emplacement of the magma when the groundmass started crystallizing at a rapid rate. The rapid growth of quartz and alkali feldspar crystallizing from the residual melt gave rise to the ubiquitous granophyric intergrowth in the late stage of crystallization. The alkali-rich residual liquid tended to concentrate toward the margin of the pluton where there is a profusion of granophyric intergrowths. 相似文献
19.
对国内29家由各地地矿行政主管局创办的地质期刊的发展现状作了概要介绍;综合整理了相关单位公布的期刊评价和引文数据等定量分析成果;简要分析了地方地质期刊的特点;提出了发挥地域优势、开展学术争鸣、强化刊文引用等有效提升期刊影响的初步建议。《贵州地质》在同类期刊中综合优势明显,具有很高水准,办刊经验值得借鉴。 相似文献
20.
中国南方岩溶地下水面源污染风险评价及防控对策 总被引：1，自引：0，他引：1
我国南方发育分布了约80万km2的碳酸盐岩地层、3 620个岩溶地下水系统,赋存了1 806×108 m3/a岩溶水资源,为南方69个城市约5 000万城市居民及8 000多万农村人口提供了供水水源。但是岩溶水受到了程度不同的污染,而农业面污染源对岩溶水所产生的污染已经远远超过非面源污染,威胁着岩溶地区供水安全。岩溶地下水污染风险评估研究意义重大。作者在全面系统地分析了南方岩溶水特点、污染类型及污染途径等的基础上,结合已有的实验研究结果总结了岩溶地下水污染的防护能力,提出了污染风险识别、污染概率估算、污染风险评价与防控的理论方法,并以贵阳为例,对岩溶地下水面源污染风险进行了评价,针对岩溶地下水面源污染特点提出了防控对策。 相似文献