Development of joints and shear fractures in the Kuqa depression and its implication to regional stress field switching     

Zhang Zhongpei  WANG Qingchen 《中国科学D辑(英文版)》2004,47(Z2)

The superimposed basin must have undergone the changes of regional stress field. Study on the nature and switch of regional stress field of superimposed basin is very useful to understanding its stress state and tectonic events during its formation and evolution. As sensitive markers of small stress changes, joint and shear fracture, characterized by consistency of orientation over wide area, can be used to reconstruct paleostress state and its evolution. Detailed observations and analysis on the orientations, geometrical patterns, sequences of joints and shear fractures and their chronological relation to faults and folds show that, the NEE-SWW systematic joints and NNW-SSE systematic joints developed in the Mesozoic and Cenozoic strata are much more prominent than NW-SE systematic joints and shear fractures with different orientations. And the NWW-SEE and NW-SE systematic joints formed later than NEE-SWW systematic joints but earlier than shear fractures with different orientations. According to the relationships between joint and shear fractures and stress, the NEE-SWW systematic joints are inferred to result from lateral weak extension caused by the late Cretaceous regional uplift, while the NNW-SSE and NW-SE systematic joints are interpreted as syn-tectonic deformation relating to strong N-S compression in the Neogene. But some conjugate shear fractures occur probably due to sinistral strike-slip faulting in the Kuqa depression. At the beginning of the Neogene, the stress field changed and the maximal principal stress σ1 switched from vertical to horizontal.  相似文献   

A Preliminary Analysis of Relations Between Tectonic Deformation of Sedimentary Cover and Basement in Kuqa Depression     

Liu Jie 《中国地震研究》2004,18(4):406-416

Study of seismic activity in the Kuqa area enables us to infer some possible active faults in basement from the epicentral distribution on different profiles. The relations between active faults in the basement and surface structures are analyzed and the difference between sedimentary cover and basement in their deformation characteristics and the genesis are discussed. The following conclusions have been drawn : ( 1 ) the epicentral distribution indicates that, the east Qiulitag and south and north Qiulitag deep faults in the basement correspond to the east and west Qiulitag anticlines, respectively. Moreover, deep faults also exist beneath the Yiqiklik and Yaken anticlines. It indicates that the formation of surface structures is controlled by deep structures; (2) A NE-trending strike-slip fault develops along the line from the western termination of Yiqiklik structure to Dongqiu Well 5 and a NW-trending active fault on the western side of Baicbeng. The two active faults across the tectonic strike are the main causes for tectonic segmentation of the Kuqa depression and possibly the cause for the middle segment (Kuqa-Baicheng) of the depression to be more shortened than both its eastern and western terminations; (3) The difference between the sedimentary cover and basement in their deformation characteristics depends mainly on the different properties of media between them.The lithospheric strength of the basement in the basin is fairly high, which determines the basement deformation to be mainly of brittle fracture seismic activity. While the strength of sedimentary cover is low, where there exist weak thin layers, such as coal and gyps. Under the effect of strong tectonic compression, the sedimentary rocks may undergo strong viscous or plastic flow deformation; meanwhile, an aseismic detachment may take place along the weak layers.  相似文献   

冀中坳陷-黄骅坳陷馆陶组热储发育差异性及成井条件     

沈俊超  王学工  贾兰凤  公利华 《水文地质工程地质》2004,31(3):40-43,54

本文论述了冀中坳陷-黄骅坳陷馆陶组热储砂岩、底部砾岩、砂砾岩的发育、孔隙度及热水水质的差异性,对热储出水特征进行了探讨,提出了馆陶组热储成井的基本条件,对冀中坳陷-黄骅坳陷馆陶组热储成井具有一定的指导意义。  相似文献   

Mesoscale Diagnosis of a Torrential Rainfall Caused by a Tropical Depression     

YU Hui  LIANG Xudong  DUAN Yihong  QI Liangbo 《Acta Meteorologica Sinica》2005,19(2):226-230

On August 5, 2001, Shanghai was struck by a torrential rainfall due to the passage of a tropical depression (TD). The rainfall intensity has been the strongest in recent 50 years. In this paper, a set of mesoscale re-analyses data and the planetary boundary layer observation from a wind profiler are used to understand the possible mechanism of such a heavy rain. Results show that the outburst of a southerly jet in the lower atmosphere triggered the explosive development of cyclonically vertical vorticity in the region with steep potential temperature surfaces in front of the TD; while the cyclonic vorticity increased notably at higher levels due to the small atmospheric vertical stability of westerly currents in the vicinity of Shanghai. The simultaneous sharp development of cyclonic vorticity at different levels should be the main cause for the torrential rainfall.  相似文献   

阿拉善地区前寒武纪斜长角闪岩的岩石学、地球化学、形成环境和年代学   总被引：8，自引：0，他引：8  

沈其韩耿元生  王新社吴春明 《岩石矿物学杂志》2005,24(1):21-31

阿拉善地区前寒武纪不同岩群、岩组和杂岩中的斜长角闪岩均呈层状产出 ,其原岩多为高铁拉斑玄武岩 ,普遍具有高钾高钛、稀土元素含量高、轻稀土元素富集的地球化学特征 ,与典型的大洋拉斑玄武岩、太古宙的TH1型和TH2 型拉斑玄武岩有较明显的区别。岩石组合特征和多种地球化学判别图解均表明 ,该区的斜长角闪岩主要形成于板内环境 ,属于板内裂陷或大陆边缘裂陷的大地构造环境。初步的同位素年代学研究表明 ,叠布斯格岩群中斜长角闪岩的原岩形成于新太古代 ,含黑云斜长角闪岩中的角闪石3 9Ar_40 Ar坪年龄和等时线年龄分别为 1918Ma和1919Ma ,说明其曾经历了古元古代角闪岩相变质作用的叠加。巴彦乌拉山岩组中斜长角闪岩形成于 2 2 71Ma～2 2 6 4Ma。波罗斯坦庙片麻杂岩中的斜长角闪岩已被 1818Ma和 1839Ma花岗片麻岩侵入 ,根据该杂岩体中斜长角闪岩与巴彦乌拉山岩组中同类岩石的地球化学特征 ,推断其形成于古元古代早期。阿拉善群德尔和通特组中的斜长角闪岩目前尚无确切的同位素年代学数据 ,但相同层位的石榴石二云母石英片岩中锆石离子探针定年已获得平均同位素年龄值为 136 3Ma ,推测它有可能形成于中元古代  相似文献   

鄂西岩溶槽谷区洼地的水位响应特征及产流阈值估算   总被引：1，自引：0，他引：1  

廖春来  罗明明  周宏 《中国岩溶》2020,39(6):802-809

以湖北省兴山县黄粮镇刘家坝和龙湾两处岩溶洼地作为研究对象，利用其降雨、水文和土壤水等监测数据，探讨灌入式补给条件下洼地汇流的水位响应特征和产流特点，并基于降雨量和洼地内明渠流量的关系，采用数学拟合方程，估算两处洼地的降雨产流阈值，进而分析了影响产流阈值的因素。结果表明:降雨强度增大，产流阈值减小；土壤前期含水率越大，越有利于坡面产流；落水洞和岩溶泉水位与降雨有较好的同步响应关系，水位变化曲线随雨强大小分别表现出“陡升陡降”和“缓升缓降”的特点；刘家坝和龙湾洼地的产流阈值分别为7.4 mm和10.6 mm。   相似文献   

封闭系统中的白云石化作用过程及其油气地质意义——以南羌塘拗陷中侏罗统布曲组白云岩为例     

孙伟  陈明  万友利  何江林  兰叶芳  卫红伟  陈浩 《地质论评》2020,66(5):1217-1229

南羌塘拗陷中侏罗统布曲组结晶白云岩作为盆地最优质的储层是通过埋藏成岩过程中封闭条件下的白云石化作用形成的，岩石所具有的高孔隙度与封闭系统中白云石化反应有关。根据对羌资11井和羌资12井布曲组的岩石结构分类、碳氧同位素组成及温度计算、流体包裹体均一温度等分析结果，可以认为：结晶白云岩碳同位素值分布区间较窄（2. 86‰~4. 27‰），氧同位素值随着白云石晶体变粗（自形程度变差）逐渐偏负（-3. 27‰~-8. 17‰），显著低于保留原始组构的白云岩，表明结晶白云岩碳源来自于先驱灰岩中的碳，其白云石化作用应是在远离大气水的封闭成岩环境中进行；结晶白云岩流体包裹体均一温度主峰值区间为90~140 ℃，且随着白云石晶粒变粗（自形程度变差），均一温度呈升高的趋势，与氧同位素计算温度变化趋势一致，表明白云石化作用过程是在封闭的条件下进行，白云石随地热增温而生长，并非受外来流体的影响。开放系统中的白云石化作用对油气储集空间的形成没有实际意义，而埋藏成岩过程中封闭系统的白云石化是形成南羌塘拗陷优质储层最为重要的成岩机制。  相似文献   

冀中坳陷束鹿凹陷潜山不整合特征与油气运聚模式     

蔡川  邱楠生  刘念  李振明  王元杰  鱼占文  焦亚先 《地质学报》2020,94(3):888-904

本文从冀中坳陷束鹿凹陷潜山顶面不整合接触类型及分布规律、结构特征及输导类型出发，精细刻画了不整合面之下半风化岩石层的垂向岩溶分带特征。在此基础上对典型剖面烃源岩热演化、油气运移进行模拟，建立了研究区潜山油气的运聚模式。结果表明，束鹿凹陷潜山顶面不整合包括4种接触类型、5种结构模式，具有3种输导类型，其中斜坡区和洼槽区西部以侧向型为主，斜坡区局部构造高点与洼中隆为侧向+圈闭型，凸起区以侧向+垂向型为主。不整合面之下半风化岩石孔缝洞体系发育，垂向上可划分为表层岩溶带、垂直渗流带以及三个水平潜流带，具有多期岩溶旋回特征。潜山顶部发育的垂直渗流带是油气沿不整合面运移的主力输导层，而内幕发育的多期水平潜流带是油气向内幕运移的潜在通道。深、浅部烃源岩热演化的差异以及与薄层砾岩是否接触导致了斜坡区与洼中隆潜山油气充注的差异，形成了斜坡区晚期薄层砾岩高效中转、不整合侧向运移、水平潜流带向内幕输导、顺向断层向上输导、反向断层圈闭成藏的油气运聚模式。  相似文献   

广西忻城福六浪洼地堵洞成库施工实践          下载免费PDF全文

邓忠  韦兴标  何德顺 《探矿工程》2020,47(11):61-69

为解决广西忻城县城关镇弄长村一带万余人饮水问题及该岩溶石山区干旱农田引水灌溉问题，在广西忻城县隆光地下河福六浪洼地3号天窗下游钻取了投料孔和帷幕灌浆孔，先在投料孔投放碎石骨料，后在帷幕灌浆孔内灌入水泥砂浆或水泥浆液对先期投放的碎石骨料进行固结，修筑地下堵体防渗帷幕对流经福六浪洼地的隆光地下河管道实施堵截，成功地截住了隆光地下河水向下游排泄量，减少了洼地积水通过天窗、落水洞向下游的渗漏量，增加了天窗向洼地的溢洪量，建成了库容约250万m3的溶洼水库，基本解决了城关镇弄长村一带万余人生活饮水难的问题，提高了该溶洼水库周边、岩溶大石山区干旱农田灌溉水平和改善了当地村民的饮水条件。  相似文献   

文昌B凹陷差异伸展- 走滑机制及控藏作用研究     

江汝锋  周家雄  杨希冰  游君君  李珊珊  陈林  张霞 《地质学报》2020,94(8):2422-2432

为查明文昌B凹陷油气富集差异性的原因，基于断裂展布和形成期次、构造样式组合、构造演化和断层活动的差异等标志，建立了差异伸展- 走滑机制，识别出19洼为伸展- 强走滑、14洼为伸展- 中等走滑、30洼为伸展- 弱走滑。差异伸展- 走滑作用控制了优质烃源岩的展布和供烃方向，控制输导体系类型和运移动力，提供物源通道和改造储层，还控制了圈闭类型和力学性质。进一步深化了走滑增压理论，基于先存断裂形态、伸展应力场右旋演化和应变差异，建立了走滑增压圈闭识别方法，识别出S型增压、右行左阶增压、斜交型增压3种走滑增压构造。研究表明，文昌B凹陷的油气富集受伸展- 走滑构造背景、源- 运时空配置关系所控制，强—中等走滑变形、发育优质中深湖源岩的文昌19洼和14洼是油气富集区。该研究成果成功推动了文昌凹陷近期的多个勘探发现。  相似文献