郯庐断裂带新生代的上地幔剪切作用与火山活动   总被引：4，自引：1，他引：4  

朱光  牛漫兰  宋传中  王道轩  刘国生 《安徽地质》2001,11(2):106-112

沿郯庐断裂带新生代大规模的幔源玄武岩喷发是伴随着上地幔剪切作用而出现的。古近纪(老第三纪)伸展活动期，断裂带在上地幔的伸展剪切及同时的软流圈上涌、岩石圈拆沉是该阶段玄武岩浆活动的主要原因。断裂带内新近纪(新第三纪)至第四纪玄武岩中的幔源包体，不但指示了土地幔韧性剪切带的存在，也反映了断裂切割深度与详细的流变学特征。在新近纪以来的区域挤压背景下，郯庐断裂带压性或压扭性的上地幔剪切一地幔交代．_‘部分熔融是该期玄武岩喷发的主要机制。  相似文献   

内蒙古大青山地区早前寒武纪变质地层的组成及特征   总被引：10，自引：0，他引：10  

徐仲元  刘正宏  杨振升 《世界地质》2001,20(3):209-218

内蒙古大青山地区是华北克拉通北缘早前寒武纪变质杂岩发育地区，也是高级变质地层发育地区。多年来，对该区早产寒武纪变质地层的组成和划分一直存在着争议。近几年来，作者以相同或相似的岩性组合为基本填图单位，以变形变质作用特征的研究为主线，结合岩浆活动作用，原岩建造等方面的研究，通过对内蒙古大青山地区的6幅、：5万区域地质调查，提出自该区早前寒武纪变质地层自下而上可划分为古太古代兴和岩群，中太古代乌拉山岩群和古元古代美岱召岩群3个岩群，并进一步划分为8个岩组。其中兴和岩群和乌拉山岩群均遭受了麻粒岩相－高角闪岩相条件下的多期强烈的变形变质作用改造，并相互参差交错地工生在一起。详细地构造解析结果表明，兴和岩群和乌拉山岩群均遭受到一期下地壳麻粒岩相环境下的近水平剪切变形和高角闪岩相条件下的近南北向和近东西向纵向构造置换作用的改造。早期近水平剪切导致乌拉山岩群的各个地层单元以透镜状岩片叠置于兴和岩群之上，后期纵向构造置换作用导致兴和岩群和乌拉山岩群的不同地层单元沿现存叶理相互穿插，造成以现存叶理为标志的“假互层”或“假夹层”。美岱召岩群为一套浅变质的碎屑沉积岩系，仅遭受绿片岩相变质，变形特征也不同于乌拉山岩群，其以角度不整合覆盖在由乌拉山岩群，兴和岩群及侵入其中变质深成岩组成的高级变质杂岩之上。  相似文献   

关于剪应力和剪应变的思考   总被引：1，自引：0，他引：1  

熊道锟 《四川地质学报》2001,21(3):129-132

对力学中广泛应用的剪应力互等定理提出了质颖，认为该定理并不能广泛成立。根据内力分析的基本原理，运用截面法分析了该定理成立的条件和适用的范围。回顾了现有剪应变概念的主要描述形式，在讨论和分析其内涵的不确定性的基础上，对剪应变的概念作了修正。  相似文献   

环空流动壁面剪应力对固井质量的影响   总被引：3，自引：0，他引：3  

郑毅  刘爱平 《探矿工程》2003,30(3):38-41

应用壁面剪应力固井解决了委内瑞拉Caracoles油田固井实践中存在的顶替效率问题。壁面剪应力固井的主要观点是：水泥浆在环空流动的壁面剪应力达到15Pa时，可以保证CBL、VDL和SBT三项胶结测井结果合格;水泥浆在环空流动的壁面剪应力达到30Pa时，可以保证CBL、VDL和SBT三项胶结测井结果优质。高的壁面剪应力可以通过紊流获得，也可以通过提高水泥浆粘切力获得。  相似文献   

等间距断裂控制机理探讨   总被引：2，自引：0，他引：2  

宇新生 《中国煤田地质》2003,15(4):4-6

断裂有时成组出现并且以规则等间距排列，这种现象有其必然性，并可以通过弹性力学的有限单元法对其生成时的应力状况予以模拟并解释。等间距断裂的形成受控于某些地质因素，如地质体物理力学特性及其边界地应力条件等。本文的讨论相信会有助于断层研究工作。  相似文献   

Les minéralisations Cu(NiBiUAuAg) d'Ifri (district du Haut Seksaoua,Maroc) : apport de l'étude texturale au débat syngenèse versus épigenèse     

Luc Barbanson  Alain Chauvet  Aziz Gaouzi  Lakhifi Badra  Mohamed Mechiche  Jean Claude Touray  Saı̈d Oukarou 《Comptes Rendus Geoscience》2003,335(14):1021-1029

The Cu ore of Ifri is a chalcopyrite stockwork hosted by Cambrian formations and was until now interpreted as a syngenetic massive sulphide deposit. Textural studies highlight two generations of pyrite early (Py I) and late (Py II) with respect to the regional deformation. The chalcopyrite stockwork overprinted Py II, outlining the epigenetic nature of the Cu mineralization. Regarding the origin of Cu-depositing fluids, the presence in the stockwork paragenesis of an U, W, Sn association and preliminary Pb/Pb dating of a brannerite belonging to this association suggest a contribution of the Tichka granite. To cite this article: L. Barbanson et al., C. R. Geoscience 335 (2003).  相似文献   

胶东地区绿岩型金矿地球化学成矿规律及其远景预测   总被引：3，自引：0，他引：3  

鹿粗  李洪志 《现代地质》1997,11(2):191-196

通过对胶东地区绿岩中韧性剪切带的地质、地球化学特征的研究，认为胶东地区变质作用、韧性剪切作用、混合岩化作用以及新华夏系构造作用和岩浆作用等在金矿的成矿作用上具有继承关系；绿岩型金矿的成矿作用和控矿规律具有特殊性，从而突破了胶东地区新华夏构造单一控矿的认识。在此基础上，对胶东地区绿岩型金矿进行了远景预测  相似文献   

Characteristics of fault rocks and paleo-earthquake source along the Koktokay-Ertai fault zone,Xinjiang,China     

史兰斌  林传勇  陈孝德  张小鸥  柏美祥 《地震学报(英文版)》1997,10(3):365-373

ＣｈａｒａｃｔｅｒｉｓｔｉｃｓｏｆｆａｕｌｔｒｏｃｋｓａｎｄｐａｌｅｏｅａｒｔｈｑｕａｋｅｓｏｕｒｃｅａｌｏｎｇｔｈｅＫｏｋｔｏｋａｙＥｒｔａｉｆａｕｌｔｚｏｎｅ，Ｘｉｎｊｉａｎｇ，ＣｈｉｎａＬＡＮＢＩＮＳＨＩ１）（史兰斌）ＣＨＵＡＮＹＯＮ...  相似文献   

Formation of the Micro-Disseminated Strata-bound Gold Deposits,With Special Reference to Structural Evolution,Miliang Area,Zhen‘an County,Shaanxi Province,China   总被引：1，自引：1，他引：1  

Zhang Fuxin  Ma Jianqin  Wei Kuangyi 《中国地球化学学报》1996,15(4):314-323

Based on detailed geologic study,the important role of structuring in the formation of gold deposits in the area is discussed with special reference to structural evolution,Syngenetic faulting contemporaneous with tectonic-volcanic events is thought to be responsible for providing the ore-forming material at depth.The lithofacies formed by highly alternating deposition of terrestrial and carbonate detritus is chemically characterized by the assemblage of Au-Sb-As,constituteing a favorable source bed for the activation and enrichment of gold.This gold source bed has undergone four major stages of structural deformation,accompanied by multi-staged alteration and mineralization.  相似文献   

Structural geology of the Dugald River ZnPbAg deposit, Mount Isa Inlier, Australia     

G. Xu 《Ore Geology Reviews》1996,11(6):339-361

The sediment-hosted ZnPbAg deposit at Dugald River is situated 87 km northeast of Mount Isa, NW Queensland. It is a mid-scale base metal accumulation restricted to a black slate sequence of low metamorphic grade. The orebody is tabular and consists of fine- to medium-grained sulphides with a dominant mineralogy of sphalerite, pyrrhotite, pyrite, galena, quartz and muscovite. Three different ore types have been recognized based on mineralization textures; laminated, banded and brecciated. The present reserve stands at 38 million tons of ore averaging 13.0% Zn, 2.1% Pb and 42 g/t Ag. A structural investigation has revealed that six stages of deformation have affected the metasediments in the Dugald River area. The first four (D₁, D₂, D₃ and D₄) are characterized by the extensive development of folds and associated axial plane cleavage. They were all generated in a ductile regime and are of considerable significance for the structural evolution of this region as well as for the emplacement and localization of the sulphide mineralization. D₅ provides a transition towards brittle deformation developing strong kink folds with subhorizontal axial planes. D₆ was a brittle event, producing E-W-trending open folds and major NE and NW strike-slip faults crosscutting all the pre-existing structural elements plus segmenting the orebody. Correlation between the development of deformation and the formation of mineralization can be observed from macro- to microscales. Relationships of mineralization with folds and cleavage indicate a post-D₂ (dominant deformation event) and probably syn-D₄ deformation timing for the ZnPbAg mineralization at Dugald River, as suggested by the ubiquitous truncations of D₂ fabrics by ore mineral assemblages throughout the deposit.  相似文献