邢北深部勘查区低角度正断层成因浅析     

赵克明 《中国煤炭地质》2009,(7):10-11

通过邢北深部勘查区钻孔中所见的断层构造迹象分析,认为原来部分定为高角度的正断层是受太行山隆起赞皇变质核杂岩东侧拆离构造带影响而派生的中、小型低角度正断层。由于变质基底与上覆沉积盖层之间为软硬差距较大的主拆离构造面,在其影响下,上覆地层发育了若干个次级拆离构造面,邢北深部低角度正断层正是受基底拆离构造影响而形成。  相似文献   

Structural Characteristics and Formation Mechanism in the Micangshan Foreland,South China   总被引：1，自引：0，他引：1  

XU Huaming  LIU Shu  QU Guosheng  LI Yanfeng  SUN Gang  LIU Kang 《《地质学报》英文版》2009,83(1):81-91

Lying at the junction of the Dabashan, Longmenshan and Qinling mountains, the Micangshan Orogenic Belt coupled with a basin is a duplex structure and back-thrust triangular belt with little horizontal displacement, small thrust faults and continuous sedimentary cover. On the basis of 3D seismic data, and through sedimentary and structural research, the Micangshan foreland can be divided into five subbelts, which from north to south are: basement thrust, frontal thrust, foreland depression-back-thrust triangle, foreland fold belt or anticline belt, and the Tongjiang Depression. Along the direction of strike from west to east, the arcuate structural belt of Micangshan can be divided into west, middle and east segments. During the collision between the Qinling and Yangtze plates, the Micangshan Orogenic Belt was subjected to the interaction of three rigid terranes: Bikou, Foping, and Fenghuangshan (a.k.a. Ziyang) terranes. The collision processes of rigid terranes controlled the structural development of the Micangshan foreland, which are: (a) the former collision between the Micangshan-Hannan and Bikou terranes forming the earlier rudiments of the structure; and (b) the later collision forming the main body of the structural belt. The formation processes of the Micangshan Orogenic Belt can be divided into four stages: (1) in the early stage of the Indosinian movement, the Micangshan-Hannan Rigid Terrane was jointed to the Qinling Plate by the clockwise subduction of the Yangtze Plate toward the Qinling Plate; (2) since the late Triassic, the earlier rudiments of the Tongnanba and Jiulongshan anticlines and corresponding syncline were formed by compression from different directions of the Bikou, Foping and Micangshan-Hannan terranes; (3) in the early stage of the Himalayan movement, the Micangshan-Hannan Terrane formed the Micangshan Nappe torwards the foreland basin and the compression stresses were mainly concentrated along both its flanks, whereas the Micangshan-Hannan Terrane wedged into the Qinling Orogenic Belt with force; (4) in the late stage of the Himalayan movement, the main collision of the Qinling Plate made the old basement rocks of the terrane uplift quickly, to form the Micangshan Orogenic Belt. The Micangshan foreland arcuate structure was formed due to the non-homogeneity of terrane movement.  相似文献   

浅论津巴布韦康尼玛拉（Connemara）金矿床地质特征及其找矿意义     

李如满  刘峰  柳凤娟 《矿产与地质》2009,23(3):258-260,267

康尼玛拉金矿床的形成与太古宙绿岩带、前寒武系变质岩关系密切,矿体、矿化蚀变体主要受NNW向断裂构造控制,属破碎蚀变岩型金矿,围岩蚀变发育,硅化、黄铁矿化、绢云母化与矿化关系密切,该矿区具有良好的找矿前景。  相似文献   

西成铅锌矿田厂坝―李家沟矿床矿石组构特征          下载免费PDF全文

李文章 《甘肃地质》2009,(2):26-29

西成铅锌矿田位于西秦岭造山带内,该区铅锌矿床点星罗棋布,含矿建造为浅海相--滨海相碎屑岩--碳酸盐岩沉积建造,矿床的生成和分布明显受层位控制,矿床类型可分为沉积变质岩型和沉积变质再造型。本文以厂坝--李家沟铅锌矿床为例,探讨典型矿石组构特征,分析区域变质对岩矿石结构、构造的影响,对比不同矿床类型矿石结构、构造差异,对本区矿产地质及成因研究和勘查找矿具有参考意义。  相似文献   

山东早前寒武纪变质地层形成年代——锆石SHRIMP U-Pb测年的证据     

王世进  ;万渝生  ;张成基  ;杨恩秀  ;宋志勇  ;王立法  ;王金光 《山东地质》2009,(10):18-24

在鲁西地区,确定了泰山岩群主体形成时代为2 750-2 700 Ma,属新太古代早期。锆石SHRIMP U-Pb定年：雁翎关组角闪变粒岩（2 747±7）Ma,柳杭组黑云变粒岩（2 739±16）Ma、（2 703±6）Ma,侵入雁翎关组底部透闪阳起片岩的片麻状石英闪长岩（2 740±6）Ma。济宁（岩）群碎屑锆石年龄（2 700-2 665）Ma,岩浆锆石年龄（2 561±24）Ma,所以济宁（岩）群形成于新太古代晚期,而不是以往认为的古元古代。在鲁东地区,发现了中太古代表壳岩系、花岗质岩石和新太古代早期TTG花岗质岩石;荆山群和粉子山群的形成时代为古元古代晚期。荆山群大理岩被锆石SHRIMP U-Pb年龄（1 868±11）Ma、（1 852±9）Ma的莱州组合西水夼单元辉长岩、闪长岩侵入,并一起遭受变质变形作用改造。  相似文献   

Blueschists of the Amassia-Stepanavan Suture Zone (Armenia): linking Tethys subduction history from E-Turkey to W-Iran     

Yann Rolland  Sandra Billo  Michel Corsini  Marc Sosson  Ghazar Galoyan 《International Journal of Earth Sciences》2009,98(3):533-550

The Amassia–Stepanavan blueschist-ophiolite complex of the Lesser Caucasus in NW Armenia is part of an Upper Cretaceous-Cenozoic belt, which presents similar metamorphic features as other suture zones from Turkey to Iran. The blueschists include calcschists, metaconglomerates, quartzites, gneisses and metabasites, suggesting a tectonic mélange within an accretionary prism. This blueschist mélange is tectonically overlain by a low-metamorphic grade ophiolite sequence composed of serpentinites, gabbro-norite pods, plagiogranites, basalts and radiolarites. The metabasites include high-P assemblages (glaucophane–aegirine–clinozoisite–phengite), which indicate maximal burial pressure of ∼1.2 GPa at ∼550°C. Most blueschists show evidence of greenschist retrogression (chlorite—epidote, actinolite), but locally epidote-amphibolite conditions were attained (garnet—epidote, Ca/Na amphibole) at a pressure of ∼0.6 GPa and a temperature of ∼500°C. This LP–MT retrogression is coeval with exhumation and nappe-stacking of lower grade units over higher grade ones. ⁴⁰Ar/³⁹Ar phengite ages obtained on the high-P assemblages range between 95 and 90 Ma, while ages obtained for epidote-amphibolite retrogression assemblages range within 73.5–71 Ma. These two metamorphic phases are significant of (1) HP metamorphism during a phase of subduction in the Cenomanian–Turonian times followed by (2) exhumation in the greenschist to epidote-amphibolite facies conditions during the Upper Campanian/Maastrichtian due to the onset of continental subduction of the South Armenian block below Eurasia.  相似文献   

U–Pb and Sm–Nd dating of high-pressure granulites from Tcholliré and Banyo regions: Evidence for a Pan-African granulite facies metamorphism in north-central Cameroon     

M. Bouyo Houketchang  S.F. Toteu  E. Deloule  J. Penaye  W.R. Van Schmus 《Journal of African Earth Sciences》2009,54(5):144-154

U–Pb (TIMS–ID and SIMS) and Sm–Nd analyses of zircons and garnet-whole rock pairs were applied on high-pressure granulite facies metapelites and metagranodiorite from Tcholliré and Banyo regions, respectively in the Adamawa–Yadé and Western Domains of the Central-African Fold Belt (CAFB) of Cameroon. Cathodoluminescence (CL) images of zircons reveal that they are made up of ubiquitous magmatitic xenocrystic cores, surrounded and/or overprinted by light unzoned recrystallized domains. U–Pb data on cores yield ages ranging from Paleoproterozoic to Neoproterozoic, which we consider as dating inheritances. Data on overgrowths and recrystallized domains give ages ranging between 594 and 604 Ma, interpreted as the time of HP granulite-facies metamorphism in the Tcholliré and Banyo regions. This is also supported by ages derived from Sm–Nd garnet-whole rock pairs. Sediments of the Tcholliré region were deposited after ca. 620 Ma from Paleoproterozoic, Mesoproteroszoic and Neoproterozoic protoliths, while those from the Banyo region were deposited after 617.6 ± 7.1 Ma essentially from Neoproterozoic protoliths.  相似文献   

藏北羌塘中部高压变质带中石榴子石白云母片岩的岩石学和变质特征   总被引：8，自引：2，他引：6  

董永胜  张修政  施建荣  王生云 《地质通报》2009,28(9):1201-1206

羌塘中部的高压变质带位于龙木错-双湖-澜沧江板块缝合带之上,由榴辉岩、蓝片岩和石榴子石白云母片岩组成,其形成过程对探讨板块缝合带的构造演化具有重要意义。以其中的石榴子石白云母片岩为研究对象,通过岩相学研究并结合电子探针成分分析,认为石榴子石白云母片岩中的石榴子石具有多期次变质结晶的特征,保留了岩石多期次变质的信息。结合岩石组构特征,最终确定石榴子石白云母片岩至少经历了3期次的变质作用。第一、二期均为绿片岩相,当时岩石不具定向构造且未达到高压;第三期为低温高压蓝片岩相变质作用,与区域上蓝片岩的形成及榴辉岩的蓝片岩相退变质作用大体同时,该期变质变形作用形成了岩石的片理,最终成为石榴子石白云母片岩,变质作用时代为218Ma左右。  相似文献   

苏鲁超高压岩石部分熔融时间的准确限定：来自含黑云母花岗岩中锆石U-Pb定年、REE和Lu-Hf同位素的证据   总被引：13，自引：8，他引：5  

刘福来  薛怀民  刘平华 《岩石学报》2009,25(5):1039-1055

在北苏鲁超高压变质带中,广泛分布强变形的新三叠纪含黑云母花岗岩和伟晶岩脉。锆石中矿物包体激光拉曼测试、阴极发光图像分析、不同性质锆石微区LA-(MC)-ICP-MS和SHRIMP U-Pb定年、REE及Lu-Hf同位素测试等综合研究结果表明,北苏鲁威海地区超高压正片麻岩在构造折返的 (高压)麻粒岩相升温减压阶段,发生部分熔融 (深熔)作用形成了花岗质岩浆,并在临近角闪岩相退变质作用之前结晶结束形成了含黑云母的花岗岩。该类含黑云母花岗岩中的锆石成因复杂,可划分为三类锆石微区。第一类为强发光效应 (白色)继承性岩浆锆石 (微区I),具有典型的岩浆结晶环带,矿物包体为Qtz+Kfs+Ap,记录的²⁰⁶Pb/²³⁸U年龄为790~782Ma;第二类为新生锆石微区 (微区II),发光强度相对较弱 (灰色-灰白色),也具有较明显的岩浆结晶环带,矿物包体为Qtz+Kfs+Ab+Ap,记录的²⁰⁶Pb/²³⁸U年龄为222~217Ma,加权平均年龄为219±2Ma,表明苏鲁超高压地体的部分熔融 (深熔)作用发生在新三叠纪,这组年龄比苏鲁地体超高压变质时代 (235~225Ma)明显偏新,指示部分熔融 (深熔)作用的时代要晚于苏鲁地体的超高压变质时代;第三类锆石微区 (微区III)围绕第二类锆石微区分布,发光强度最弱 (黑色),也具有典型的岩浆结晶环带,矿物包体十分少见,为Qtz+Ap,记录的²⁰⁶Pb/²³⁸U年龄集中于216~209Ma之间,加权平均年龄为214±2Ma,应代表部分熔融 (深熔)而成的岩浆结晶结束的年龄,这组年龄比苏鲁地体构造折返晚期角闪岩相退变质时代(210~200Ma)偏老,表明新生岩浆结晶结束的时间要早于角闪岩相退变质时代。继承性岩浆结晶锆石 (微区I) ¹⁷⁶Hf/¹⁷⁷Hf(t)=0.281975~0.281984,¹⁷⁶Hf/¹⁷⁷Hf=0.00196~0.00221,ε_Hf(t)=-11.6~-11.8,相应的t_DM2=2160~2170Ma,与研究区周围新元古代 (795~730Ma)正片麻岩继承性岩浆结晶锆石的Lu-Hf同位素特征十分相似,表明新元古代正片麻岩是新三叠纪部分熔融 (深熔)成因的含黑云母花岗岩的母岩。新三叠纪新生岩浆结晶锆石的核部 (微区II)和边部 (微区III)具有类似的¹⁷⁶Hf/¹⁷⁷Hf(t)、¹⁷⁶Hf/¹⁷⁷Hf比值和ε_Hf(t)值,¹⁷⁶Hf/¹⁷⁷Hf(t)=0.282110~0.282199,¹⁷⁶Hf/¹⁷⁷Hf=0.00041~0.00183,ε_Hf(t)=-15.8~-19.1,t_DM2=1980~2130Ma,表明新三叠纪由超高压正片麻岩部分熔融而成的岩浆自结晶开始到结束是在一个相对封闭体系条件下完成的。晚期角闪岩相退变质作用对其Lu-Hf同位素体系也未造成破坏。  相似文献   

新疆西南天山木扎尔特河一带低压泥质麻粒岩岩石学特征、独居石U-Th-Pb定年及其地质意义   总被引：6，自引：5，他引：1  

苟龙龙  张立飞 《岩石学报》2009,25(9):2271-2280

古南天山洋闭合过程中,由于洋壳俯冲产生的岛弧岩浆作用加热大陆地壳,在新疆西南天山木扎尔特一带形成了一套低压高温泥质麻粒岩相变质岩石.本文用Theriak-Domino热力学软件对该套岩石中的堇青石榴夕线石黑云母片麻岩和含夕线石堇青石榴黑云母片麻岩进行了岩石学相平衡计算研究,得到它们峰期变质的温压条件分别是：T=630～674℃,P=5.2～5.5kbar和T=645～684℃,P=5.4～5.7kbar.并采用独居石Th-U-Pb电子探针定年方法,对样品WQ006中的3颗独居石进行了原位年龄测定(38个分析点),得到2组等时线年龄,分别是376±8Ma和280σ8Ma(2σ).结合独居石的岩相学特征,提出了新疆西南天山低压高温麻粒岩相峰期变质作用的时代为280±8Ma,而376±8Ma(2σ)可能为原沉积岩的原岩/成岩年龄.表明西南天山洋壳开始俯冲发生在晚古生代,进一步证明了西南天山造山带俯冲碰撞发生在晚二叠纪之后的观点.  相似文献