我国核地球物理勘查的若干新进展   总被引：2，自引：0，他引：2       下载免费PDF全文

吴慧山  谈成龙 《地球物理学报》1997,40(Z1):317-325

回顾了近半个世纪以来，特别是近几年来我国核地球物理勘查的发展及取得的成就．它已由50年代创建初期的单纯用于找铀矿，发展到现在在环境科学、水文地质和工程地质、寻找油气田、钾盐、磷矿、铜锡矿等方面的全方位应用；在理论上有所突破，方法技术上有所创新，并已逐步走向系列化和标准化；在与其他学科相互渗透方面得到了发展；以及在油气、煤炭测井的测试仪器等方面也都有重要进展．本文还对核地球物理今后的发展提出了看法，首先，为适应多领域应用和方法技术本身的发展，应深化应用基础理论研究；其次，要发展和提高测量结果的推断解释水平，研究消除、减少干扰因素的理论和技术；第三，应更多地运用近代科学技术的新成果，创立自已的理论和方法；第四，要根据经济的发展和生产的需要，使核物探稳步走向市场．  相似文献   

Structure and tectonics of convergent plate margins     

Aleš Špi?ák  Ond?ej ?adek  E.Robert Engdahl 《Physics of the Earth and Planetary Interiors》2004,141(4):241

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Influence of the zone of weakness on dip angle and shear heating of subducted slabs     

Martin Kuka?ka  Ctirad Matyska 《Physics of the Earth and Planetary Interiors》2004,141(4):243-252

We study the importance of the zones of weakness and the pattern of downgoing flow in steady-state models of subducting lithosphere, which interacts mechanically and thermally with the ambient mantle. The non-linear system of governing equations consists of (i) the momentum equation in stream function formulation and (ii) the steady-state heat transfer equation including conduction and advection of heat and dissipation. A finite element method has been applied to this system. We consider the viscosity to be a non-linear function of both the temperature and the stream function. In steady-state two-dimensional (2D) flow, the stream function isolines follow material trajectories. They are used to follow the top of the subducting slab, which because of its possible increase in water content, is assumed to have a lower viscosity. The zone of weakness has been thus obtained in the self-consistent fashion since the stream function as well as the temperature are the output from our modeling and no a priori assumptions about the shape of the bending lithosphere are taken into account. It was shown that several orders decrease of viscosity in the zone of weakness is required to obtain the dip angle of about 45°. If the decrease of viscosity is not sufficient enough, the subducted slab either sinks almost vertically or does not exhibit a plate-like behavior. We have also demonstrated that shear heating can unrealistically increase at the zone of weakness for fast subductions if decrease of viscosity is underestimated.  相似文献   

A Modeling Study of the Effects of Anomalous Snow Cover over the Tibetan Plateau upon the South Asian Summer Monsoon   总被引：1，自引：0，他引：1  

刘华强  孙照渤王举 闵锦忠 《大气科学进展》2004,21(6):964-975

The effect of anomalous snow cover over the Tibetan Plateau upon the South Asian summer monsoon is investigated by numerical simulations using the NCAR regional climate model (RegCM2) into which gravity wave drag has been introduced. The simulations adopt relatively realistic snow mass forcings based on Scanning Multi-channel Microwave Radiometer (SNINIR) pentad snow depth data. The physical mechanism and spatial structure of the sensitivity of the South Asian early summer monsoon to snow cover anomaly over the Tibetan Plateau are revealed. The main results are summarized as follows. The heavier than normal snow cover over the Plateau can obviously reduce the shortwave radiation absorbed by surface through the albedo effect, which is compensated by weaker upward sensible heat flux associated with colder surface temperature, whereas the effects of snow melting and evaporation are relatively smaller.The anomalies of surface heat fluxes can last until June and become unobvious in July. The decrease of the Plateau surface temperature caused by heavier snow cover reaches its maximum value from late April to early May. The atmospheric cooling in the mid-upper troposphere over the Plateau and its surrounding areas is most obvious in May and can keep a fairly strong intensity in June. In contrast, there is warming to the south of the Plateau in the mid-lower troposphere from April to June with a maximum value in May.The heavier snow cover over the Plateau can reduce the intensity of the South Asian summer monsoon and rainfall to some extent, but this influence is only obvious in early summer and almost disappears in later stages.  相似文献   

粤北下庄铀矿田富铀矿找矿前景探讨   总被引：7，自引：4，他引：7  

吴烈勤  谭正中 《铀矿地质》2004,20(1):10-15

本文通过对下庄矿田铀矿找矿潜力分析 ,探讨区内富铀矿找矿方向和找矿前景。研究表明 :下庄矿田是铀元素高度富集的矿集区 ,具有较大的找矿潜力和发展前景 ,是粤北富铀矿找矿的重点地区之一 ;区内“交点”型、碱交代碎裂岩型和群脉型铀矿是该区今后找矿的主要目标类型和找矿方向。  相似文献   

粤北笋洞花岗岩的形成时代、地球化学特征与成因   总被引：25，自引：10，他引：25  

凌洪飞沈渭洲  邓平蒋少涌  高剑峰叶海敏濮巍  谭正中 《岩石学报》2004,20(3):413-424

笋洞花岗岩体是粤北贵东复式花岗岩体的一个重要组成部分。锆石U-Pb年龄为189.1±0.7Ma,是燕山早期岩浆活动产物。该岩体的主要元素显示富硅、富碱、强过铝质和低 CaO/Na_2O比值等特征;微量元素方面,富集Rb,Th,U,Ce,Sm,Y,亏损 Ba,Sr,P,Ti;LREE轻微富集(LREE/HREE=6.6～8.8,(La/Yb)_N=6.44～10.74),Eu亏损明显(δEu=0.14～0.31);它具有低的ε_(Nd)(t)(-11.4～-9.3),高的δ~(18)O(10.2～12.7‰)、(~(87)Sr/~(86)Sr);(0.72949～0.74923)、~(206)Pb/~(204)Pb(18.180～18.488)、~(207)Pb/~(204)Pb(15.655～15.661)和古老的Nd模式年龄(1762～1933Ma)。上述这些特征表明,笋洞岩体属于典型的壳源型花岗岩,是在地壳伸展-减薄的构造背景下,通过以泥质成分为主的古-中元古代变质沉积岩部分熔融的方式形成。  相似文献   

个旧锡矿区域地壳演化与成矿探讨   总被引：3，自引：0，他引：3  

谈树成  秦德先  陈爱兵  范柱国  薛传东  李俊  夏既胜  普传杰 《矿物学报》2004,24(2):157-163

个旧锡多金属矿床是驰名中外的特大型矿床，过去认为是燕山晚期“花岗岩岩浆期后气液矿床”。但通过探讨区域上前震旦纪地壳演化、震旦纪-早古生代地壳演化、泥盆纪-三叠纪地壳演化以及侏罗纪-第四纪地壳演化，以及与成矿之间的关系，发现个旧矿区至少经历了印支中晚期海底基性火山-沉积成矿、印支中晚期海底喷流热水沉积成矿、燕山晚期花岗岩叠加改造成矿以及喜山期陆相表生沉积成矿作用，厘定了个旧锡矿区的印支中晚期海底基性火山．沉积Sn-Cu-Zn(Au)矿床系列、印支中晚期海底喷流-沉积Sn-Cu-Pb-Zn矿床系列、燕山晚期花岗岩叠加改造Sn-Cu-W-Be-Bi-Pb-Zn-Ag矿床系列、喜山期陆相表生沉积砂矿矿床系列等4大矿床系列及12种矿床类型。  相似文献   

塔里木盆地西部古岩盐地质地球化学特征与成钾条件分析   总被引：11，自引：1，他引：11  

谭红兵  马海州  马万栋  董亚萍  张西营  许建新 《矿物岩石地球化学通报》2004,23(3):194-199

塔里木盆地是我国重要的成盐盆地,为我国最有远景的找古钾矿地区之一。本文通过多年野外实地调查和大量岩盐样品的化学分析,特别是岩盐中可以指示沉积阶段的Br×103/Cl系数等区域分布特征,联系前人研究资料,分别从构造环境、地层和岩相古地理、地球化学特征等方面进行了成钾条件分析。结果表明,莎车盆地西部喀什坳陷和库车盆地中部拜城坳陷宏观地质特征均有利于钾盐沉积;岩盐地球化学组成相对于正常海相沉积表现出明显的贫Br特征,属海陆交互相或海源陆相沉积。相比之下,莎车盆地的喀什次级坳陷是目前最有前景的找钾远景区。  相似文献   

楚雄盆地晚三叠世古地理变迁   总被引：4，自引：1，他引：4       下载免费PDF全文

尹福光  万方  许效松  谭富文  陈明  汪正江 《沉积与特提斯地质》2004,24(3):52-57

楚雄盆地晚三叠世为一建立在扬子板块西缘前寒武纪基底之上的海相—海陆过渡相—陆相沉积盆地。中三叠世拉丁期—晚三叠世卡尼期沉积了一套深水的灰色薄层状粉砂质泥岩和泥质粉砂岩；诺利期早期以华坪隆起为界有两个沉降中心，华坪隆起以西的推覆体之上为广海陆架相的细碎屑岩沉积、远源浊积岩，以东为局限环境下的细碎屑岩沉积夹浊积岩；诺利期晚期为大规模的三角洲前缘砂体组成下超的复合体，古地理格局继续保持东西向分带，呈对称分布，盆地西部为陆相、海陆过渡相，盆地中部为海相沉积。瑞替期在原形盆地中形成舍资组的河流—滨岸沉积，在推覆体上形成白土田组的冲洪积物。总之，表现古地理变迁为一个由西东逐渐超覆、由下向上粒度逐渐变粗、由海相变为陆相的过程。  相似文献   

基于遗传算法的巷道位移反分析研究   总被引：4，自引：4，他引：4  

赵同彬  谭云亮  刘传孝 《岩土力学》2004,25(Z1):107-109

将遗传算法应用到位移反分析研究中,采用遗传算法与FLAC数值软件相结合的手段,研制了弹塑性巷道位移反分析程序。对该程序测试的结果表明,用遗传算法这一模拟生物进化的方法,进行巷道位移反分析,可以同时反演E,μ,C,ф,σx,σy,τxy7个参数,反演精度较高。  相似文献