大巴山西段高川地体构造变形特征及其意义   总被引：1，自引：0，他引：1  

胡健民董树文  孟庆任 《地质通报》2008,27(12)

勉略缝合带华北与华南大陆于印支期完成拼合的主要拼接带,在中国大陆的形成与演化中占据重要地位。但是,勉略带的东、西延伸,至今没有确定的结论,尤其陕西省勉县以东到湖北随州一带,还没有找到确凿的缝合带的证据。现今一些重要的文章多认为勉略带在勉县以东到达宁陕县两河口之后向南转折,沿着高川岩片的位置顺大巴山弧形构造带向东延伸到湖北随州一带。然而,本文的研究表明,高川岩片是一个独立于大巴山构造带的外来地质体,并称之为高川地体。高川地体是一个由近南北向右行走滑断层与轴向近南北向的走滑剪切褶皱构造组成的右行走滑构造系统,作者认为,它是大巴山冲断推覆构造向南推覆过程中,被从原勉略缝合带中挤过来的一片,它仅仅是被挟持在大巴山冲断—推覆构造带与大巴山前陆构造带之间的地壳浅层地质体,高川地体现在的位置不能代表勉略带向东的延伸。因此,大巴山弧形构造带也不是中国南北大陆最终碰撞拼贴的位置  相似文献   

Structural and remote sensing studies of the southern Betsimisaraka Suture, Madagascar     

Tsilavo Raharimahefa  Timothy M. Kusky 《Gondwana Research》2006,10(1-2):186

An assessment of the southern Betsimisaraka Suture (B.S.) of southeastern Madagascar using remote sensing and field investigation reveals a complex deformation history. Image processing of Landsat ETM+data and JERS-I Synthetic Aperture Radar (SAR) imagery was integrated with field observations of structural geology and field petrography. The southern B.S. divides the Precambrian basement rocks of Madagascar in two parts. The western part includes Proterozoic rocks whereas the eastern part is an Archean block, named the Masora block. The southern part of the B.S. includes high-grade metamorphic rocks, recording strong deformation and has mineral deposits including chromite, nickel, and emerald, characteristic of oceanic material that is compatible with a suture zone.Large-scale structural features indicate ductile deformation including three generations of folding (F1, F2, and F3) associated with dextral shearing. The first folding event (F1) shows a succession of folds with NE striking axial planes. The second folding event (F2) mainly has north–south striking axial planes and the last event (F3) is represented by mega folds that have ENE–WSW axial plane directions and have NNW and SSE contractional strain patterns. Closure of the Mozambique Ocean between two components of Gondwana sandwiched rocks of the B.S. and formed upright folds and shortening zones which produced N–S trending lineaments. Later dextral movements followed the contraction and formed NW–SE trending lineaments and N–S trending normal faults associated with dextral strike slip faults and fractures.  相似文献   

A N–S receiver function profile across the Variscides and Caledonides in SW Ireland     

Michael Landes  J. R. R. Ritter  B. M. O'Reilly  P. W. Readman  V. C. Do 《Geophysical Journal International》2006,166(2):814-824

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新疆鄯善康古尔塔格蛇绿岩及其大地构造意义   总被引：4，自引：1，他引：4  

李文铅  夏斌吴国干  王核王冉 《岩石学报》2005,21(6):1617-1632

康古尔塔格蛇绿岩的岩石组合为变质橄榄岩-堆晶橄榄岩-辉长岩-斜长花岗岩-辉绿岩-玄武岩。方辉橄榄岩（蛇纹岩）、蛇纹石化辉石岩、蚀变辉长岩与特罗多斯蛇绿岩中同类型岩石类似，岩石总体低钾。变质橄榄岩MgO／（MgO＋TFeO）为0．834～0．866，TiO，（wt％）为0．02％，为SSZ型蛇绿岩的变质橄榄岩。玄武岩的构造环境判别显示其形成于边缘海盆。放射虫硅质岩的Al2O3／（Al2O3＋Fe2O3）值平均为0．047，MnO／TiO2比值平均为0．93，Ce具负异常，Ce／Ce^＊=0．548，Lan／Cen=1．661．表明放射虫硅质岩的形成环境与洋中脊有密切关系。该蛇绿岩位于塔里木板块和哈萨克斯坦-准噶尔板块的艾比湖-康古尔塔格缝合线上，为一套无序产出的古生代北天山洋在该区的古洋壳残片。  相似文献   

Receiver function analysis of the crust and upper mantle from the North German Basin to the Archaean Baltic Shield   总被引：1，自引：0，他引：1  

A. Alinaghi  G. Bock  R. Kind  W. Hanka  K. Wylegalla  TORSVEKALAPKOWorking Groups 《Geophysical Journal International》2003,155(2):641-652

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雅鲁藏布江缝合带中部硅岩地球化学特征及构造环境制约   总被引：4，自引：0，他引：4       下载免费PDF全文

孙立新  万晓樵  贾建称  胡华斌 《地质学报》2004,78(3):380-389

硅岩在雅鲁藏布江缝合带广泛发育。在 1∶ 2 5万萨嘎县幅、桑桑区幅区域地质调查中 ,在缝合带及其南侧宗卓组中识别出 3种硅岩沉积组合 :1嘎学群内与玄武岩伴生的硅岩 ;2构造混杂带内夹于页岩中的硅岩 ;3宗卓组内夹于页岩—岩屑石英杂砂岩的硅岩。在硅岩中分离出的放射虫组合时代为白垩纪。运用地球化学研究手段 ,对硅岩岩石组合、岩石化学、微量元素和稀土元素特征进行了综合分析 ,与玄武岩伴生的硅岩 Al/ (Al Fe Mn)为 0 .5 33～ 0 .5 4 6 <0 .6 19(除 9号样外 ) ,Ce/ Ce* 为 0 .6 7(平均 ) ,L an/ Ybn为 0 .83～ 1.37和 L an/ Cen为0 .82～ 2 .2 3;夹于页岩中的硅岩 Al/ (Al Fe Mn)为 0 .5 5 7～ 0 .6 19,Ce/ Ce*为 0 .995～ 1.35 0 ,L an/ Ybn为 0 .71～ 1.0 3和 L an/ Cen为 0 .6 8～ 0 .98;宗卓组内的硅岩 Al/ (Al Fe Mn)为 0 .6 15～ 0 .70 7>0 .6 19,Ce/ Ce* 为 0 .94～1.14 ,L an/ Ybn 为 1.4 4～ 1.6 6和 L an/ Cen 为 0 .85～ 1.0 7。研究证实 ,3种背景的硅岩均反映非热水或生物成因。嘎学群内与玄武岩伴生的硅岩具深水盆地沉积特征 ;宗卓组中的硅岩具典型大陆边缘沉积环境特征 ;构造混杂带内的硅岩形成于近大陆边缘环境中  相似文献   

Evidence for Neotethys rooted within the Vardar suture zone from the Voras Massif, northernmost Greece   总被引：2，自引：0，他引：2  

Sally A. M. Brown  Alastair H. F. Robertson   《Tectonophysics》2004,381(1-4):143

Three conflicting models are currently proposed for the location and tectonic setting of the Eurasian continental margin and adjacent Tethys ocean in the Balkan region during Mesozoic–Early Tertiary time. Model 1 places the Eurasian margin within the Rhodope zone relatively close to the Moesian platform. A Tethyan oceanic basin was located to the south bordering a large “Serbo-Pelagonian” microcontinent. Model 2 correlates an integral “Serbo-Pelagonian” continental unit with the Eurasian margin and locates the Tethys further southwest. Model 3 envisages the Pelagonian zone and the Serbo-Macedonian zone as conjugate continental units separated by a Tethyan ocean that was sutured in Early Tertiary time to create the Vardar zone of northern Greece and former Yugoslavia. These published alternatives are tested in this paper based on a study of the tectono-stratigraphy of a completely exposed transect located in the Voras Mountains of northernmost Greece. The outcrop extends across the Vardar zone, from the Pelagonian zone in the west to the Serbo-Macedonian zone in the east.Within the Voras Massif, six east-dipping imbricate thrust sheets are recognised. Of these, Units 1–4 correlate with the regional Pelagonian zone in the west (and related Almopias sub-zone). By contrast, Units 5–6 show a contrasting tectono-stratigraphy and correlate with the Paikon Massif and the Serbo-Macedonian zone to the east. These units form a stack of thrust sheets, with Unit 1 at the base and Unit 6 at the top. Unstacking these thrust sheets places ophiolitic units between the Pelagonian zone and the Serbo-Macedonian zone, as in Model 3. Additional implications are, first, that the Paikon Massif cannot be seen as a window of Pelagonian basement, as in Model 1, and, secondly, Jurassic andesitic volcanics of the Paikon Massif locally preserve a gneissose continental basement, ruling out a recently suggested origin as an intra-oceanic arc.We envisage that the Almopias (Vardar) ocean rifted in Triassic time, followed by seafloor spreading. The Almopias ocean was consumed beneath the Serbo-Macedonian margin in Jurassic time, generating subduction-related arc volcanism in the Paikon Massif and related units. Ophiolites were emplaced onto the Pelagonian margin in the west and covered by Late Jurassic (pre-Kimmeridgian) conglomerates. Other ophiolitic rocks formed within the Vardar zone (Ano Garefi ophiolite, Unit 4) in latest Jurassic–Early Cretaceous time and were not deformed until Early Tertiary time. The Vardar zone finally sutured in the Early Tertiary creating the present imbricate thrust structure of the Voras Mountains.  相似文献   

Delineation and assessment of Central Indian Suture through lineament extraction approach using Remote Sensing and Geographic Information System     

Kuntal Ganguly  Tarik Mitran 《国际地球制图》2016,31(3):308-327

Lineament extraction approach allowed mapping of larger number of lineaments in a classical manner in tectonic and structural studies. In the present study, various techniques were adopted to extract lineaments using Landsat ETM+ images. To remove the biasness of the images, some pre-processing techniques like stream ordering, band differencing, colour texturing were employed to enhance the edges of the structural features. Extracted lineaments and its distribution and orientation were mapped using ArcGIS Spatial analyst tool. Results of the study showed maximum number of lineaments were oriented in the ENE–SWS direction with 63° overall inclination. Accuracy assessment and validation were made with respect to visual interpretation and overlaying the lineament on Digital Topographic Model as well as with respect to an existing geological lineament map of the study site. The result of accuracy assessment indicates higher compatibility of Central Indian Suture with the geological map of the study area.  相似文献   

The Late Triassic I–Type Granites from the Longmu Co–Shuanghu Suture Zone in the interior of Tibetan Plateau, China: Petrogenesis and Implication for Slab Break–Off     

ZHAO Zhen  WU Zhenhan  LU Lu  YU Junqiu  WU Yanjun 《《地质学报》英文版》2018,92(3):935-951

The Jiangaidarina granitic mass(JM) is an important part of the magmatic belt in Longmu CoShuanghu Suture Zone(LSSZ) in the central Tibetan Plateau. An integrated research involving wholerock geochemistry, zircon LA-ICP-MS U-Pb ages and Hf isotopic compositions was carried out to define the timing, genesis and tectonic setting of the JM. Zircon LA-ICP-MS U-Pb ages have been obtained ranging from 210 to 215 Ma, rather than the Early Jurassic as previously thought. Fifteen granite samples contain hornblendes and show a negative correlation between P_2 O_5 and SiO_2, indicating that the JM is an I-type granite. All the granites are enriched in LREE relative to HREE, with negative Eu anomalies(Eu/Eu*=0.56-0.81), and have similar trace elements patterns, with depletion of Ba, Nb, Sr and P. These suggest that the JM was fractionated, and this is also proved by the characteristic of negative correlations between oxide elements(TiO_2, MgO, FeOt, MnO, CaO) and SiO_2. Almost all ε_(Hf)(t) values of the granites are between-10.3 and-5.8, implying that the JM has a crustal source intimately related with the South Qiangtang Block(SQB), except for one(+10.2), showing a minor contribution from mantle source.Moreover, relatively low Na_2 O/K_2 O ratios(0.42-0.93) and high A/CNK values(0.91-1.50) reflect that the JM was predominately derived from the medium-high potassium basaltic crust, interacted with greywacke. Our new geochemical data and geochronological results imply that the Late Triassic magmas were generated in a post-collisional tectonic setting, probably caused by slab break-off of the Longmu Co-Shuanghu Tethyan Ocean(LSTO). This mechanism caused the asthenosphere upwelling, formed extension setting, offered an enormous amount of heat, and provided favorable conditions for emplacement of voluminous felsic magmas. Furthermore, the LSTO could be completely closed during the Middle Triassic, succeed by continental collision and later the slab broke off in the Late Triassic.  相似文献   

Research achievements of the Qinghai-Tibet Plateau based on 60 years of aeromagnetic surveys     

《China Geology》2021,4(1):147-177

The Qinghai-Tibet Plateau (also referred to as the Plateau) has long received much attention from the community of geoscience due to its unique geographical location and rich mineral resources. This paper reviews the aeromagnetic surveys in the Plateau in the past 60 years and summarizes relevant research achievements, which mainly include the followings. (1) The boundaries between the Plateau and its surrounding regions have been clarified. In detail, its western boundary is restricted by West Kunlun-Altyn Tagh arc-shaped magnetic anomaly zone forming due to the arc-shaped connection of the Altyn Tagh and Kangxiwa faults and its eastern boundary consists of the boundaries among different magnetic fields along the Longnan (Wudu)-Kangding Fault. Meanwhile, the fault on the northern margin of the Northern Qilian Mountains serves as its northern boundary. (2) The Plateau is mainly composed of four orogens that were stitched together, namely East Kunlun-Qilian, Hoh-Xil-Songpan, Chamdo-Southwestern Sanjiang (Nujiang, Lancang, and Jinsha rivers in southeastern China), and Gangdese-Himalaya orogens. (3) The basement of the Plateau is dominated by weakly magnetic Proterozoic metamorphic rocks and lacks strongly magnetic Archean crystalline basement of stable continents such as the Tarim and Sichuan blocks. Therefore, it exhibits the characteristics of unstable orogenic basement. (4) The Yarlung-Zangbo suture zone forming due to continent-continent collisions since the Cenozoic shows double aeromagnetic anomaly zones. Therefore, it can be inferred that the Yarlung-Zangbo suture zone formed from the Indian Plate subducting towards and colliding with the Eurasian Plate twice. (5) A huge negative aeromagnetic anomaly in nearly SN trending has been discovered in the middle part of the Plateau, indicating a giant deep thermal-tectonic zone. (6) A dual-layer magnetic structure has been revealed in the Plateau. It consists of shallow magnetic anomaly zones in nearly EW and NW trending and deep magnetic anomaly zones in nearly SN trending. They overlap vertically and cross horizontally, showing the flyover-type geological structure of the Plateau. (7) A group of NW-trending faults occur in eastern Tibet, which is intersected rather than connected by the nearly EW trending that develop in middle-west Tibet. (8) As for the central uplift zone that occurs through the Qiangtang Basin, its metamorphic basement tends to gradually descend from west to east, showing the form of steps. The Qiangtang Basin is divided into the northern and southern part by the central uplift zone in it. The basement in the Qiangtang Basin is deep in the north and west and shallow in the south and west. The basement in the northern Qiangtang Basin is deep and relatively stable and thus is more favorable for the generation and preservation of oil and gas. Up to now, 19 favorable tectonic regions of oil and gas have been determined in the Qiangtang Basin. (9) A total of 21 prospecting areas of mineral resources have been delineated and thousands of ore-bearing (or mineralization) anomalies have been discovered. Additionally, the formation and uplift mechanism of the Plateau are briefly discussed in this paper.©2021 China Geology Editorial Office.  相似文献