南秦岭三叠系裂陷槽边界断裂带多金属成矿带特征     

张红斌  王才进 《甘肃地质》2011,(3):60-65

南秦岭三叠系裂陷槽主要分布在合作—宕昌—两当大断裂与腊子口—舟曲—成县大断裂之间,向东伸入陕西界内,向西延伸到青海省,以甘肃陇南相关三叠纪地层研究程度最高。其北界为传统意义上中秦岭与南秦岭的分界线,沿此断裂构造带目前已发现有众多的多金属矿点及矿化点。南界属于著名的白龙江背斜的北翼,沿此断裂构造带最近也不断发现了一系列金...  相似文献   

基于Biot-Gassmann 方程的流体替换技术在番禺天然气区PY 气田的应用     

轩义华  袁立忠  汪瑞良  秦成岗  金志臻 《世界地质》2011,30(1):60-64

珠江口盆地番禺天然气区PY 气田位于坡折带上,特殊的沉积环境导致该气田已钻探的各井 T50 储层泊松比关系异常,含油气性特征非常复杂。为更好的判断储层的含油气性,利用Biot-Gassmann 方程对坡折带储层的流体性质进行了替换,考查不同流体性质下储层的含油气响应特征。研究结果表明: Biot-Gassmann 方程能有效的用于坡折带储层的流体替换研究; 坡折带T50 储层含水和含气时的AVO 响应特征相近,但两者响应的幅值不同,含水砂岩的幅值更小。  相似文献   

大别-苏鲁造山带、华南晚中生代花岗岩时空分布及应力场对比          下载免费PDF全文

丁汝鑫  周祖翼 《地学前缘》2011,18(1):9-14

花岗岩原地重熔学说为解释华南晚中生代(晚侏罗世-早白垩世)花岗岩时空分布的大地构造成因提供了一种新的视角.而通过对比可以发现,大别-苏鲁造山带及其以北附近区域(尤其是苏鲁造山带及其以北附近区域)与华南晚中生代花岗岩时空分布规律及应力场具有高度的相似性和一致性,即花岗岩展布方向以北东向为主,从北西到南东方向由老变新;而且...  相似文献   

天津北大港构造带东翼断裂活动浅析     

万贵龙  张德会  张守仁 《地球学报》2011,32(3):373-381

构造因素对油气的分布起着控制性的作用,断裂活动特征决定着一个盆地或凹陷油气的富集与分布.本文通过对北大港构造带东翼所有断裂的仔细研究,统计分析了区内20条规模较大断裂的断距在纵横向上的变化,结合20余条地震剖面和8条构造发育史剖面,综合分析认为北大港构造带东翼的断裂活动主要为:古近纪活动期和新构造期(0.78 Ma至今...  相似文献   

山西省落家河铜矿地质特征及矿床成因浅析     

孙桂琴  霍卫民 《化工矿产地质》2011,(4):232-238

落家河矿田位于中条三叉裂谷南东支的落家河构造剥蚀天窗内,该区域位于线性构造和弧形构造的交叉部位,是成矿有利部位.落家河矿区赋矿岩性为新太古界绛县群宋家山组绿泥片岩和变细碧岩.宋家山组一套钠质中基—中酸性火山凝灰岩夹正常沉积钙质副变质岩组成.经变质后的绿片岩层是主要找矿层位,特别是该岩层沿走向或倾向变化大和膨胀部位.硅化...  相似文献   

栖霞市西陡崖矿床地质特征及找矿方向     

谢军民  肖翔  史宏江  崔煜峰 《山东地质》2011,(6):1-5

西陡崖金矿为台前-陡崖成矿带上又一新发现的金矿床,该金矿受台前-陡崖断裂带严格控制,矿体呈脉状、透镜状;矿床平均品位3.96×10-6,平均厚度1.67 m;围岩蚀变主要有黄铁绢英岩化,矿石中金属矿物主要为银金矿、自然金,黄铁矿等,矿床属岩浆期后中低温热液交代破碎蚀变岩型矿床。通过分析研究,西陡崖金矿在深部及外围找矿前景较大。  相似文献   

Formation of the Dongmozhazhua Pb–Zn Deposit in the Thrust‐Fold Setting of the Tibetan Plateau,China: Evidence from Fluid Inclusion and Stable Isotope Data     

YingChao LIU  ZengQian HOU  ZhuSen YANG  ShiHong TIAN  TianNan YANG  YuCai SONG  HongRui ZHANG  Emmanuel John M. CARRANZA 《Resource Geology》2011,61(4):384-406

The Dongmozhazhua deposit, the largest Pb–Zn deposit in south Qinghai, China, is stratabound, carbonate‐hosted and associated with epigenetic dolomitization and silicification of Lower–Middle Permian—Upper Triassic limestones in the hanging walls of a Cenozoic thrust fault system. The mineralization is localized in a Cenozoic thrust‐folded belt along the northeastern edge of the Tibetan plateau, which was formed due to the India–Asia plate collision during the early Tertiary. The deposit comprises 16 orebodies with variable thicknesses (1.5–26.3 m) and lengths (160–1820 m). The ores occur as dissemination, vein, and breccia cement. The main sulfide assemblage is sphalerite + galena + pyrite + marcasite ± chalcopyrite ± tetrahedrite, and gangue minerals consist mainly of calcite, dolomite, barite, and quartz. Samples of pre‐ to post‐ore stages calcite yielded δ¹³C and δ¹⁸O values that are, respectively, similar to and lower than those yielded by the host limestones, suggesting that the calcite formed from fluids derived from carbonate dissolution. Fluid inclusions in calcite and sphalerite in the polymetallic sulfidization stage mostly comprise liquid and gas phases at room temperature, with moderate homogenization temperatures (100–140°C) and high salinities (21–28 wt% NaCl eq.). Micro‐thermometric fluid inclusion data point to polysaline brines as ore‐forming fluids. The δD and δ¹⁸O values of ore fluids, cation compositions of fluid inclusions, and geological information suggest two main possible fluid sources, namely basinal brines and evaporated seawater. The fluid inclusion data and regional geology suggest that basinal brines derived from Tertiary basins located southeast of the Dongmozhazhua deposit migrated along deep detachment zones of the regional thrust system, leached substantial base metals from country rocks, and finally ascended along thrust faults at Dongmozhazhua. There, the base‐metal‐rich basinal brines mixed with bacterially‐reduced H₂S‐bearing fluids derived from evaporated seawater preserved in the Permo–Triassic carbonate strata. The mixing of the two fluids resulted in Pb–Zn mineralization. The Dongmozhazhua Pb–Zn deposit has many characteristics that are similar to MVT Pb–Zn deposits worldwide.  相似文献   

Cobalt‐Bearing Grunerite in the Metamorphosed Banded Iron Formation in Orissa,India     

Prasanta Kumar NAYAK  Birendra Kumar MOHAPATRA  Prem Prakash SINGH  Ranjit Kumar MARTHA 《Resource Geology》2011,61(3):281-289

Banded iron formation (BIF) comprising high grade iron ore are exposed in Gorumahisani‐Sulaipat‐Badampahar belt in the east of North Orissa Craton, India. The ores are multiply deformed and metamorphosed to amphibolite facies. The mineral assemblage in the BIF comprises grunerite, magnetite/martite/goethite and quartz. Relict carbonate phases are sometimes noticed within thick iron mesobands. Grunerite crystals exhibit needles to fibrous lamellae and platy form or often sheaf‐like aggregates in linear and radial arrangement. Accicular grunerite also occur within intergranular space of magnetite/martite. Grunerite needles/accicules show higher reflectivity in chert mesoband and matching reflectance with that of adjacent magnetite/martite in iron mesoband. Some grunerite lamellae sinter into micron size magnetite platelets. This grunerite has high ferrous oxide and cobalt oxide content but is low in Mg‐ and Mn‐oxide compared to the ones, reported from BIFs, of Western Australia, Nigeria, France, USA and Quebec. The protolith of this BIF is considered to be carbonate containing sediments, with high concentrations of Fe and Si but lower contents of cobalt and chromium ± Mg, Mn and Ni. During submarine weathering quartz, sheet silicate (greenalite) and Fe‐Co‐Cr (Mg‐Mn‐Ni)‐carbonate solid solution were formed. At the outset of the regional metamorphic episode grunerite, euhedral magnetite and recrystalized quartz were developed. Magnetite was grown at the expense of carbonate and later martitized under post‐metamorphic conditions. With the increasing grade of metamorphism greenalite transformed to grunerite.  相似文献   

内蒙古乌斯尼黑蛇绿混杂岩带形成时代的地质新证据   总被引：3，自引：0，他引：3  

鲍庆中  张长捷  吴之理 《地质与资源》2011,20(1):16-20

贺根山-乌斯尼黑蛇绿混杂岩带的属性和形成时代存在明显的认识上的分歧.早期认为是二叠纪侵入的超镁铁质岩体.该超镁铁质岩体侵入了下二叠统格根敖包组,并被哲斯组地层不整合覆盖,形成时代为二叠纪.20世纪80年代以来,通过中国北方板块构造研究,在硅质岩中采集到的一系列化石资料表明,贺根山地区蛇绿混杂岩的形成时代应为中-晚泥盆世...  相似文献   

藏南昂仁县桑桑地区林子宗群火山岩的形成时代 和地球化学特征   总被引：4，自引：1，他引：3  

谢克家  曾令森  刘静  高利娥  胡古月 《地质通报》2011,30(9):1339-1352

桑桑地区林子宗群火山岩Sr、Nd同位素地球化学特征和SHRIMP锆石U-Pb地质年代学数据表明:①林子宗火山岩以高钾流纹岩为主,属于高钾钙碱性系列岩石,形成于49.8Ma± 0.92 Ma,属于帕那组火山岩地层;②林子宗火山岩稀土元素配分模式较为一致,相对于HREE,强烈富集LREE;③林子宗火山岩具有相对低的初始Sr同位素值(87Sr/86Sr(i)=0.70488~0.70569)和较高的初始Nd值(εNd(i)=-1.38~-1.58);④总体上富集大离子亲石元素,亏损高场强元素,与岛弧型火山岩的地球化学特征类似。桑桑地区林子宗火山岩在形成过程中明显受到角闪石和斜长石分离结晶作用的影响。可能是俯冲的新特提斯洋板片断离或变陡,进而导致经历过俯冲交代作用的富集岩石圈地幔甚至局部下地壳发生部分熔融,形成的初始岩浆发生混合作用,并在近封闭条件下发生高度分离结晶作用的产物。结合已有的结果,认为冈底斯带南带普遍经历了50Ma左右的岩浆作用。  相似文献