华北地块南缘向北的薄皮推覆构造及北秦岭加里东造山作用   总被引：1，自引：0，他引：1  

马志和  李海平  计文化 《陕西地质》1996,(1)

通过对华北地块南缘向北的薄皮推覆构造及北秦岭构造带结构、构造特征分析，认为它们同属于加里东期造山作用产物。北秦岭属于加里东造山带根带（即核部），华北地块南缘小秦岭（及豫西）地区属于该期造山带的外带，渭北褶皱隆起区则属于其前锋冲断褶带。秦岭造山带现今几何模型是一个复合型不对称扇状大陆造山带。  相似文献   

Crustal thickening under the palaeo-meso-Proterozoic Delhi Fold Belt in northwestern India: evidence from deep reflection profiling   总被引：1，自引：0，他引：1  

H. C. Tewari  M. M. Dixit  N. Madhava Rao  N. Venkateswaralu  V. Vijaya Rao 《Geophysical Journal International》1997,129(3):657-668

The results of deep reflection profiling studies carried out across the palaeo-meso-Proterozoic Delhi Fold Belt (DFB) and the Archaean Bhilwara Gneissic Complex (BGC) in the northwest Indian platform are discussed in this paper. This region is a zone of Proterozoic collision. The collision appears to be responsible for listric faults in the upper crust, which represent the boundaries of the Delhi exposures. In these blocks the lower crust appears to lie NW of the respective surface exposures and the reflectivity pattern does not correspond to the exposed blocks. A fairly reflective lower crust northwest of the DFB exposures appears to be the downward continuation of the DFB upper crust. The poorly reflective lower crust under the exposed DFB may be the westward extension of the BGC upper crust at depth. Thus, the lower crust in this region can be divided into the fairly reflective Marwar Basin (MB)-DFB crust and a poorly reflective BGC crust. Vertically oriented igneous intrusions may have disturbed the lamellar lower-crustal structure of the BGC, resulting in a dome-shaped poorly reflective lower crust whose base, not traceable in the reflection data, may have a maximum depth of about 50 km, as indicated by the gravity modelling.
The DFB appears to be a zone of thick (45-50 km) crust where the lower crust has doubled in width. This has resulted in three Moho reflection bands, two of which are dipping SE from 12.5 to 15.0 s two-way time (TWT) and from 14.5 to 16.0 s TWT. Another band of subhorizontal Moho reflections, at ≈ 12.5 s TWT, may have developed during the crustal perturbations related to a post-Delhi tectonic orogeny. The signatures of the Proterozoic collision, in the form of strong SE-dipping reflections in the lower crust and Moho, have been preserved in the DFB, indicating that the crust here has not undergone any significant ductile deformation since at least after the Delhi rifting event.  相似文献   

济阳坳陷及其邻近地区早第三纪海侵问题之我见   总被引：5，自引：0，他引：5  

张玉宾 《沉积与特提斯地质》1997,17(1):45-49

本文针对长期争议的早第三纪时期济阳坳陷及其邻近地区是否存在海侵问题，根据沉积特征及古生物资料，以济阳坳陷为例，重点研究了下第三系沙河街组二段至一段的演化特征，提出了新的观点——海啸。指出了遍布于整个渤海湾盆地的沙二段上部冲积相是由强海啸形成，它也是造成沙一段时期发生第三纪以来最大湖淹的主要原因。认为海啸的成因很可能与星体对地球的碰撞有关，属于地质时期的偶然事件  相似文献   

山西省五台山晚太古代镁铁质—超镁铁质岩：一种可能的古蛇绿混杂岩   总被引：18，自引：5，他引：18  

王凯怡  李继亮 《岩石学报》1997,13(2):139-151

在五台山地区，在原五台群南北金岗库组内分布着大小不等的超镁铁质岩块体，包括蛇纹岩，滑石片岩，透闪石片岩，辉石岩，变辉长岩，斜长角闪岩和簿层硅质岩。这些块体作为外来岩块产出在强变形的复理石型基质中，分别代表了阜平陆块和弧地质体及恒山陆块和弧地质体之间的海洋岩石圈的残余  相似文献   

A review on the lithospheric structures in the Tibetan Plateau and constraints for dynamics   总被引：3，自引：0，他引：3  

Rongsheng Zeng  Zhifeng Ding  Qingju Wu 《Pure and Applied Geophysics》1995,145(3-4):425-443

In the last decade, several international joint projects were conducted in the Tibetan Plateau by Chinese, American and French geophysicists and geologists. In the present review, the results from vertical reflections, wide-angle reflections and broadband digital seismic recordings are reviewed and compared. Constraints for the dynamics of continent-continent collision from the lithospheric structures, seismicity, focal mechanism and anisotropy are discussed.The velocities ofPn,Sn, , were accurately determined by using their travel times from local events. They evidenced that the uppermost mantle underneath the Tibetan Plateau was similar to that of the ordinary continental mantle.The reflection profile from INDEPTH-I furnishes convincing evidence that the Indian crust penetrates into the Tibetan lower crust. The results from teleseismic waveform inversion reveal that the Moho discontinuity dips northwards, and an offset of Moho occurs near Bangong suture.The fact that materials within the Tibetan Plateau escape laterally has been proposed by several authors. Recent data and studies provide further convincing evidence that eastward mass transfer does occur, and their paths and natures are investigated.Some authors suggested that the large strike slip faults (Kun Lun, Xianshuihe) in the eastern plateau may be related to the lateral extrusion. However, most of the strike slips are left-lateral, and extrusion could not occur without right-lateral strike slips. Recent observations of the focal mechanisms and geological structure indicate that the earthquakes in the Yanshiping-Changdu belt are left-lateral strike slip. It is the southeast zone of the left-lateral slip faults in the eastern Tibetan plateau. Geological and seismological evidence show that the Bencuo-Jiali belt is the only large right-lateral fault in the eastern plateau. It was proposed that the present eastward extrusion occurs between the Yangshiping-Changdu left-lateral strike slip and the Bencuo-Jiali right-lateral strike slip. The other left-lateral strike slips north of the Yangshiping-Changdu belt are considered to be the fossils of the ancient flow paths.  相似文献   

珠江三角洲的活动断裂与区域稳定性分析     

钟建强  聂颂平 《热带海洋学报》1991,(4)

珠江三角洲的活动断裂主要为弱活动断裂,分别属于NW,NE和EW向三组断裂,活动断裂是控制该三角洲断块运动和地震活动的关键。珠江三角洲主要为区域稳定性中等地区。  相似文献   

From oblique subduction to intra-continental transpression: Structures of the southern Kermadec-Hikurangi margin from multibeam bathymetry,side-scan sonar and seismic reflection     

Jean-Yves Collot  Jean Delteil  Keith B. Lewis  Bryan Davy  Geoffroy Lamarche  Jean-Christophe Audru  Phil Barnes  Franck Chanier  Eric Chaumillon  Serge Lallemand  Bernard Mercier de Lepinay  Alan Orpin  Bernard Pelletier  Marc Sosson  Bertrand Toussaint  Chris Uruski 《Marine Geophysical Researches》1996,18(2-4):357-381

The southern Kermadec-Hikurangi convergent margin, east of New Zealand, accommodates the oblique subduction of the oceanic Hikurangi Plateau at rates of 4–5 cm/yr. Swath bathymetry and sidescan data, together with seismic reflection and geopotential data obtained during the GEODYNZ-SUD cruise, showed major changes in tectonic style along the margin. The changes reflect the size and abundance of seamounts on the subducting plateau, the presence and thickness of trench-fill turbidites, and the change to increasing obliquity and intracontinental transpression towards the south. In this paper, we provide evidence that faulting with a significant strike-slip component is widespread along the entire 1000 km margin. Subduction of the northeastern scrap of the Hikurangi Plateau is marked by an offset in the Kermadec Trench and adjacent margin, and by a major NW-trending tear fault in the scarp. To the south, the southern Kermadec Trench is devoid of turbidite fill and the adjacent margin is characterized by an up to 1200 m high scarp that locally separates apparent clockwise rotated blocks on the upper slope from strike-slip faults and mass wasting on the lower slope. The northern Hikurangi Trough has at least 1 km of trench-fill but its adjacent margin is characterized by tectonic erosion. The toe of the margin is indented by 10–25 km for more than 200 km, and this is inferred to be the result of repeated impacts of the large seamounts that are abundant on the northern Hikurangi Plateau. The two most recent impacts have left major indentations in the margin. The central Hikurangi margin is characterized by development of a wide accretionary wedge on the lower slope, and by transpression of presubduction passive margin sediments on the upper slope. Shortening across the wedge together with a component of strike-slip motion on the upper slope supports an interpretation of some strain partitioning. The southern Hikurangi margin is a narrow, mainly compressive belt along a very oblique, apparently locked subduction zone.  相似文献   

武夷山新元古代蛇绿混杂岩岩石地球化学特征   总被引：5，自引：0，他引：5       下载免费PDF全文

王淼  舒良树 《中国地质》2007,34(4):572-583

岩石地球化学研究表明,华南造山带东段武夷山新元古代蛇绿混杂岩中的玄武岩和安山岩可以分为两种类型:一种为拉斑玄武岩类,TiO2含量为2.26%～2.59%(平均2.43%),轻稀土元素比重稀土元素富集,(La)N/(Yb)N=6.4～9.4(平均7.8),相对富集Nb、Ta和Ti,微量元素特征类似于洋岛玄武岩;另一种岩石属于钙碱系列,TiO2含量为0.69%～0.93%(平均0.83%),表现为轻稀土元素富集,(La)N/(Yb)N=4.2～12.6(平均8.4),略显Eu负异常,并以低Nb、Ta、Ti等元素为特征,富集Ba、Rb、Th、K等大离子亲石元素,具有岛弧玄武岩的特征,属于俯冲作用的产物。蛇绿混杂岩中这两类岩石共生,记录了扬子地块和华夏地块之间古大洋消减闭合和弧-弧碰撞拼贴的历史。  相似文献   

用陆块旋转解释藏东南渐新世—中新世伸展作用——来自点苍山及邻区变质核杂岩的证据   总被引：11，自引：0，他引：11  

刘俊来  曹淑云  翟云峰  宋志杰  王安建  修群业  曹殿华  高兰  管烨 《地学前缘》2007,14(4):40-48

沿红河断裂带(RRFZ)分布的点苍山变质核杂岩是一个不完整的变质核杂岩,它由两个特征迥异的单元组成,包括被同构造二长花岗岩侵入角闪岩相构造岩组成的下盘和绿片岩相的拆离断层带。下盘岩石包括具有高温构造组合,具有指示左行走滑剪切运动方向的L型糜棱岩或LS型糜棱岩。拆离断层带是一个上盘向E到SE伸展剪切的低温剪切带,由具有剪应变和压应变的典型S-L糜棱岩构成。低温构造岩也包括发育于下盘的几个糜棱岩化似斑状二长花岗岩侵入体。变质核杂岩与西侧覆盖未变质的中生代沉积岩并置,东部受第四纪断层作用影响为沿洱海分布的更新世—全新世沉积盆地。通过对点苍山变质核杂岩的构造研究,结合邻区变质核杂岩的地质年代学及古地磁学分析,我们认为:位于东南亚红河断裂和实皆断裂带之间的扇形区域内出现的变质核杂岩与渐新世—中新世时期区域性伸展作用有关,而伸展作用是由印支地块的差异性旋转产生的,其原因是由于约33Ma开始斜向俯冲的印度板块的顺时针旋转和回退所致。  相似文献   

昆仑造山带晚泥盆世沉积特征及构造古地理环境   总被引：6，自引：4，他引：6  

陈守建  李荣社  计文化  赵振明  孟勇  史秉德 《大地构造与成矿学》2007,31(1):44-51

昆仑造山带基本构造-地层格架奠基于古生代,晚泥盆世是加里东造山旋回和华力西造山旋回转换的关键阶段,加里东碰撞造山和其后的伸展裂陷等记录均存在于晚泥盆世沉积地层中。西昆仑晚泥盆世奇自拉夫组为一套紫红色碎屑岩沉积,属典型的碰撞造山型磨拉石建造,为加里东碰撞造山的产物;东昆仑晚泥盆世黑山沟组和哈尔扎组岩性组合特征与牦牛山组极为相似,均为一套陆相、滨浅海相的碎屑岩、碳酸盐岩和中酸性火山岩组合,为典型的裂陷伸展型磨拉石建造,是晚古生代裂陷伸展盆地演化开始的标志。  相似文献