利用震源机制解走向判定地震影响场长轴方向     

徐志双  任静  谭专条  高小跃  陈雅慧  杨志高  李志强 《地震研究》2022,45(1):88-99

为了评估以震源机制解走向作为影响场长轴方向的适用性,以1970—2020年145个破坏性地震为研究对象,研究各地震的震源机制解走向和极震区长轴方向之间的偏差,发现两者平均差值为17.0°;走滑型、逆断型和正断型地震分别占研究地震总数的56.6%、19.3%和6.2%,其震源机制解走向与极震区长轴方向的平均差值分别为16.4°、16.2°和20.6°;有82.8%的地震的震源机制解走向与极震区长轴走向差值小于30°,说明该方法是可行的。通过统计研究2010—2020年等震线长轴方向明显的50个强震震中附近区域历史强震震源机制解走向与极震区长轴方向差值,结果表明:有13个地震震中30 km范围内有历史强震发生,最近历史强震震源机制解走向与极震区长轴方向差值小于30°的有8个(62%)。如果在距离地震震中30 km以内发生过历史强震,则可以综合考虑距震中最近的历史强震震源机制解走向和活动断裂走向来判定影响场长轴方向。  相似文献   

Influence of seismic wave type and incident direction on the dynamic response of tall concrete-faced rockfill dams          下载免费PDF全文

Chen-guang Zhou  De-gao Zou  Xiang Yu 《地震科学（英文版）》2022,35(5):343-354

Owing to the stochastic behavior of earthquakes and complex crustal structure, wave type and incident direction are uncertain when seismic waves arrive at a structure. In addition, because of the different types of the structures and terrains, the traveling wave effects have different influences on the dynamic response of the structures. For the tall concrete-faced rockfill dam (CFRD), it is not only built in the complex terrain such as river valley, but also its height has reached 300 m level, which puts forward higher requirements for the seismic safety of the anti-seepage system mainly comprising concrete face slabs, especially the accurate location of the weak area in seism. Considering the limitations of the traditional uniform vibration analysis method, we implemented an efficient dynamic interaction analysis between a tall CFRD and its foundation using a non-uniform wave input method with a viscous-spring artificial boundary and equivalent nodal loads. This method was then applied to investigate the dynamic stress distribution on the concrete face slabs for different seismic wave types and incident directions. The results indicate that dam-foundation interactions behave differently at different wave incident angles, and that the traveling wave effect becomes more evident in valley topography. Seismic wave type and incident direction dramatically influenced stress in the face slab, and the extreme stress values and distribution law will vary under oblique wave incidence. The influence of the incident direction on slab stress was particularly apparent when SH-waves arrived from the left bank. Specifically, the extreme stress values in the face slab increased with an increasing incident angle. Interestingly, the locations of the extreme stress values changed mainly along the axis of the dam, and did not exhibit large changes in height. The seismic safety of CFRDs is therefore lower at higher incident angles from an anti-seepage perspective. Therefore, it is necessary to consider both the seismic wave type and incident direction during seismic capacity evaluations of tall CFRDs.  相似文献   

甘肃省西和县页水河铅锌矿床地质特征及找矿方向          下载免费PDF全文

秦术凯  杨永峰  罗伟 《地质找矿论丛》2021,36(3):276-282

甘肃省西和县页水河铅锌矿地处西秦岭铅锌(金)多金属成矿带之西成铅锌矿田的西部,经过多年生产探矿,矿床规模不断扩大。铅锌矿体产于中泥盆统红岭山组生物灰岩与千枚岩接触部位,其含矿性与地层层位、特定的岩性、褶皱及断裂的关系密切。文章总结了矿床地质特征,分析了控矿因素及找矿标志,指出了下一步的找矿方向。  相似文献   

刚果(金)卢阿拉巴省康隆卡铜钴矿床地质特征及找矿前景     

张银  胡登攀  余璨  翟建军 《地质与资源》2021,30(4):450

刚果卢阿拉巴省隶属于非洲板块克拉通,该区发育了世界著名的加丹加弧形铜成矿带,康隆卡铜矿即产于该成矿带上.在资料系统收集和二次分析的基础上,结合大量的野外勘探工作,系统厘定康隆卡铜矿矿体特征、矿石类型、围岩蚀变特征,分析地层、构造对成矿的控制,结合物探工作,总结铜矿成矿规律.研究表明：1）矿床中矿石矿物以孔雀石、蓝铜矿、黑铜矿等次生氧化矿物为主,矿石结构以自形-他形粒状结构为主,矿石构造主要为多孔构造、角砾状构造、浸染状构造;2）罗安群木瓦夏组层状白云质砂岩（RSF）及蜂窝状硅质白云岩（RSC）为康隆卡铜矿重要的赋矿层位,矿（化）体层控性质显著;3）构造在空间上与成矿显示出密切联系,坎苏祁（Kansuki）断裂、次级断裂及褶皱构造共同控制着含矿层位,为矿质运移、沉淀、叠加提供场所,初步认为康隆卡铜矿为沉积-热液改造型铜钴矿床;4）结合物探工作成果及找矿标志,NE向次级构造所对应的矿致异常深部具有矿（化）体富集、膨大趋势,找矿潜力良好,矿区内民采遗迹、南部矿点均为找矿工作重点.  相似文献   

内蒙古新巴尔虎地区土壤地球化学异常特征与找矿方向          下载免费PDF全文

裴圣良  袁建江  黄明达 《地质找矿论丛》2018,33(3):449-457

新巴尔虎左地区位于得尔布干成矿带西南端,现已在周边发现多个与火山岩、次火山岩有关的大型及超大型热液型矿床。但本区工作程度相对较低,本次研究在总结前人工作的基础上,对其开展1∶5万土壤地球化学测量。通过分析18种元素的土壤地球化学特征,发现本区Pb、Zn、Ag、Mo等元素具有较好的异常。本区异常多分布于成矿有利部位,具有良好的找矿潜力。综合考虑地球化学异常元素的组合及异常区成矿地质条件和地球化学条件,圈定综合异常12处,并确定4个找矿靶区,为下一步找矿工作提供了依据。  相似文献   

Hydrochemical Dynamic Characteristics and Evolution of Underground Brine in the Mahai Salt Lake of the Qaidam Basin Qinghai-Tibet Plateau   总被引：1，自引：0，他引：1  

HU Shuy  ZHAO Quansheng  WANG Guangcai  ZHANG Jianwei  FENG Juan 《《地质学报》英文版》2018,92(5):1981-1990

The mineral rock salts present in the Mahai Salt Lake of the Qaidam basin exhibit high solubilities in water. In addition, the multicomponent underground brine exhibits a high salinity and is easily precipitated. In the natural state, brine transport in the brine layer is extremely slow, and the brine is in a relatively stable chemical equilibrium state with the rock salt media. However, during mining, both the seepage and the chemical fields fluctuate significantly, thereby disrupting the equilibrium and leading to variations in the chemical composition and dynamic characteristics of the brine. Therefore, we selected underground brine from the Mahai Salt Lake, collecting a total of 183 brine samples over three stages of mining (i.e., the early stage of underground brine extraction, the initial stage of mining, and the later stage of mining). Using a range of analytical techniques, the chemical dynamics of the underground brine water and its evolution were systematically studied. We found that evaporation and enrichment were the main mechanisms of underground brine evolution in the Mahai Salt Lake, with cation exchange and mineral dissolution/precipitation being key factors in determining the dynamic characteristics and evolution of the brine.  相似文献   

宁夏照壁山铁矿成矿地质特征与找矿方向          下载免费PDF全文

李净  海连富  母彩霞  马文文  杨站伟 《地质找矿论丛》2018,33(2):243-247

文章从区域地质背景和矿区地质特征入手,结合前人研究成果,深入分析了照壁山铁矿床地质特征和成矿规律,探讨了矿床成因类型,建立了找矿标志。研究发现:照壁山铁矿主要产于石炭系土坡组和臭牛沟组的砂岩、粉砂岩中,矿体主要沿着近EW向的断裂和裂隙分布,构造控矿明显;矿体多呈脉状、透镜状、似层状,具有原生矿石和氧化矿石2中类型,围岩蚀变表现为硅化、褐铁矿化、碳酸盐化、黄铁矿化等,围岩蚀变较强;铁矿的形成主要与中酸性岩浆的侵入关系密切,矿床类型为中低温热液矿床;近EW向的构造破碎带、弧形构造的扩容带、层间裂隙以及"硅钙面"附近是寻找铁矿的有利部位,在其深部还具有较大找矿潜力。  相似文献   

露天灰岩矿纹理特征分析及面向对象的分类     

张永彬 《地质与勘探》2018,54(2):348-357

矿产资源过度开发造成了严重的环境污染,可持续发展面临严峻挑战,矿山治理迫在眉睫。遥感信息提取技术能够便捷地获取矿山开发信息,为矿山治理提供依据。然而,目前信息提取的精度和自动化程度仍有提升空间,并且就矿产类型而言,关于石灰岩矿开采信息提取的研究甚少。针对以上现状,本文以唐山市的一处灰岩矿山为例,以Landsat-8影像作为基础数据,通过计算不同地物的纹理信息,包括地物均值、方差、信息熵、偏离度和数据范围,构造了能够突出露天灰岩矿开采区域的纹理指数模型(texture variance index,简称TVI)。结合已有的光谱和空间特征,设定准确的阈值并建立决策树,以面向对象方法为依托,进行露天灰岩矿山开采边界的信息提取。结果表明,将纹理方差指数作为灰岩矿山开发信息提取的规则之一,总体精度、用户精度和Kappa系数与原有决策树相比皆有所提高。以文中灰岩矿开采范围提取结果为基础,根据高分辨率影像的纹理特征,进一步实现了新矿区与待复垦旧矿区的分类,总体精度约为0.916。  相似文献   

皖江经济带地热资源调查与开发利用          下载免费PDF全文

陈学锋  魏永霞  李永军 《中国地质调查》2018,5(2):57-63

地热资源调查是皖江经济带地质调查的重要工作之一,是调整能源结构,构建环境友好型社会的要求。基于皖江经济带以往地热资源调查评价成果,阐述研究区地热资源的分布特点、形成机理、种类及资源总量,分析总结研究区目前地热资源开发利用现状及存在问题: 皖江经济带地热资源虽然丰富,但仅有部分水热型地热资源开发利用程度高,且资源利用效率较低; 水热型地热资源以温热水、温水为主,总体品位不高; 浅层地热能资源总量丰富,分布广泛,开发利用技术成熟,适宜大力开发利用,但大部分未开展调查评价工作。建议采取梯级或循环利用措施提高利用效率,综合开发利用地热资源; 突破现有模式,寻找高品位地热资源; 开展县级浅层地热能调查评价工作; 建设地热资源开发利用监管平台。  相似文献   

“Source-Diagenesis-Accumulation” enrichment and accumulation regularity of marine shale gas in southern China     

《China Geology》2018,1(3):319-330

After the breakthrough of shale gas exploration and development in the Ordovician Wufeng Formation (Fm.) and Silurian Longmaxi Fm. of Chongqing Jiaoshiba area, Changning-Weiyuan area, etc. in Sichuan basin, a series of discovery and breakthrough were obtained by China Geological Survey in the Cambrian Niutitang Fm. and Sinian Doushantuo Fm. shale of the areas with complicated structure outside Sichuan basin. Based on the understanding of the law of shale gas enrichment in Longmaxi Fm. in the basin, this paper puts forward three elements of the formation and enrichment of shale gas, which are the “Source”, the “Diagenesis” and the “Accumulation”, after deeply studying the law shale gas enrichment and accumulation in Sinian-Cambrian reservoir of the complex structure area outside the basin. The “Source” means the sedimentary environment and petrological characteristics of organic shale. The “Diagenesis” means the basin tectonic subsidence and hydrocarbon generation and expulsion process of organic matter. The “Accumulation” means the tectonic uplift and shale gas preservation. It is proposed that the Sinian-Cambrian and Ordovician-Silurian black shale series in the middle and upper Yangtze region of southern China were both formed in the deep-water shelf environment of rift trough and foreland basin respectively. The dessert intervals were formed in the strong reduction environment under transgressive system tract. The shale lithology belongs to calcium-siliceous and charcoal-siliceous respectively. Based on the summary of structural evolution in Yangtze area, the correlation of structural burial depth with shale diagenesis and the coupling evolution of organic matter with pore structure are discussed. Combining with structural styles, the preservation conditions of shale gas are discussed. Five types of shale gas reservoir control models are further described. Two types of future exploration directions, which are reverse fault syncline and paleo-uplift margin in complex structural area outside the basin, are proposed.  相似文献