青藏高原班公湖-怒江缝合带丁青-碧土段大地构造演化   总被引：5，自引：2，他引：3  

蒋光武  谢尧武  白珍平  西诺朗杰  强巴扎西  彭兴阶 《地质通报》2009,28(9):1259-1266

藏东班公湖-怒江缝合带丁青-碧土段位于该缝合带由东西向转向南北向的转折部位,夹持于冈瓦纳大陆冈底斯-察隅陆块与泛华夏扬子大陆昌都-思茅陆块之间,经历过强烈伸展、挤压、碰撞、急剧沉降和隆升,是地质构造极其复杂的造山带。其沉积构造环境复杂多样,与该缝合带发展演化有关的岩浆活动极其强烈、频繁,并发育有高压变质带。丁青-碧土-怒江洋盆经历了较为完整的威尔逊旋回,包括裂谷-初始洋盆阶段、洋盆扩张阶段、俯冲消减阶段、封闭碰撞阶段的发展和演化。  相似文献   

Recognition of Paleo-Tethys Suture Zone in eastern Myanmar     

Hla Hla AUNG 《地球学报》2009,30(Z1):1-3

The site of final closure of Paleo-Tethys Ocean during the Triassic-Jurassic was marked by the colli-sional event between the Shan Massif and Indochina plate, in eastern Myanmar. Previous site of consumption of Paleo-Tethys is now occupied by a complex zone of suturing and deformation along Than Lwin River and in the east of it, formed by drastic tectonic evolution. It is geographically located approximately between longitudes 98E and 100E, and it extends northwards to Yunnan and southwards into West Thailand. The sigmoidal wrench struc-tures of suture zone is situated in the east of step-like structures of Shan Massif, and the western boundary of the suture zone must be immediately on the west side of Than Lwin River and the eastern boundary is near the east border of Myanmar. The area is largely covered by younger rocks of Paleozoic and Mesozoic age. The Upper Pa-leozoic units of Carboniferous to Permian comprise limestone and dolomite of the Plateau Limestone overlying unconformably the Lower Paleozoic rocks. Metasedimentary rocks of the Carboniferous and their metamorphic equivalents and the flysch-like Triassic-Jurassic units are found as folded and thrusted beds in the area. Large complex of granitic rocks of Late Triassic are also found. Metavolcanics, gabbro and a large number of chromite occur along with these units. A preliminary delineation of a suture zone as the site of closure of Paleo-Tethys Ocean in Myanmar territory is made for the first time and this zone is believed to be a tectonic linkage between Changning-Menglian belt of West China and Inthanon Zone of West Thailand.  相似文献   

Opening and closing process of the Paleo-Tethys in Northern Thailand     

Hidetoshi HARA  Koji WAKITA  Jun-ichiro KURODA  Toshiyuki KURIHARA  Katsumi UENO  Yoshihito KAMATA  Ken-ichiro HISADA  Punya CHARUSIRI  Thasinee CHAROENTITIRAT  Pol CHAODUMRONG 《地球学报》2009,30(Z1):12-12

The Paleo-Tethys formed a large ocean basin that existed between Laurasia and Gondwana during Late Paleozoic to Early Mesozoic times. It opened in the Early Devonian by the rifting of Gondwanaland and closed at around latest Triassic time by the collision of the Cimmerian continent to Laurasia (Metcalfe, 1999). We reconstructed opening and closing process of the Paleo-Tethys in Northern Thailand.  相似文献   

Carboniferous foraminifers from the lower part of Paleo-Tethyan seamount-type carbonates in the Changning-Menglian Belt, western Yunnan, Southwest China     

Tin Tin LATT  Tsutomu NAKAZAWA  WANG Xiang-dong  Katsumi UENO 《地球学报》2009,30(Z1):35-36

The Changning-Menglian Belt in West Yunnan, Southwest China is well-known as a closed remnant of the Paleo-Tethys Ocean in East Asia (Wu et al., 1995; Liu et al., 1996). It is delineated to the east with the Lincang Massif by the Changning-Shuangjiang Fault and to the west with the Baoshan Block by the Kejie-Nandinghe Fault, and is generally subdivided into three zones: east, central, and west zones. In the central zone, various kinds of oceanic rocks such as harzburgite, cumulate websterite, gabbro, both mid-oceanic ridge basalt and oceanic island basalt, Devonian-Triassic radiolarian chert, and Carbonifer-ous-Permian massive and huge carbonates with basaltic effusives as their pedestal are exposed (Liu et al., 1991, 1996; Wu et al., 1995; Ueno et al., 2003). These Central zone rocks are now interpreted to have been emplaced as nappes structurally overlying the East and West zones, which are considered as consisting mainly of passive margin sediments of the Baoshan Block (Wu, 1991; Ueno et al., 2003).  相似文献   

措勤地区竟柱山组沉积特征及构造意义   总被引：3，自引：0，他引：3       下载免费PDF全文

唐熊  陶晓风 《沉积与特提斯地质》2009,29(1):53-57

上白垩统竟柱山组在西藏措勤地区主要沿班公湖-怒江缝合带、且坎-古昌-阿索断裂带和塔若错北-达瓦错南-秋措麦凹陷带断续分布。主要为一套磨拉石的紫红色碎屑岩,其沉积环境以扇三角洲和三角洲为主。扇三角洲和三角洲的前积层理指示了其进积方向,表明早期物源来自北部,而晚期来自南部的陆源物质增加。竞柱山组磨拉石沉积的发育,是班公湖-怒江缝合带造山运动的证据。  相似文献   

云县-景谷火山弧带大中河晚志留世火山岩的发现及其地质意义   总被引：9，自引：4，他引：5  

毛晓长  王立全  李冰  王保弟  王冬兵  尹福光  孙志明 《岩石学报》2012,28(5):1517-1528

云县-景谷火山弧带大中河地区新识别出一套晚志留世中基性-中酸性火山岩组合,其LA-ICPMS锆石U-Pb年龄为421.2±1.2Ma和417.6±5.1Ma。该套火山岩具有富铝(12.73%～16.63%)、富钠(K₂O/Na₂O=0.56～0.99)和高Mg^#(46.0～50.0)的特征,属于钙碱性系列岩石;同时富集轻稀土,Eu具有不同程度的弱亏损,亏损高场强元素(Nb、Ta、Ti),具有正ε_Nd(t)值(3.86～4.39)和较高的Th/Ta比值(15～17),显示与活动大陆边缘岛弧型火山岩相似的地球化学性质。大中河晚志留世火山岩很可能是俯冲沉积物流体交代地幔楔物质部分熔融的产物,并在岩浆上升过程中经历了一定的分离结晶作用和浅部地壳物质的同化混染;结合区域同期(410～420Ma)岩浆活动及相关的高压变质事件分析,应为原-古特提斯洋在早古生代末期向东俯冲消减作用的产物,从而为扬子陆块西部边缘晚古生代"三江"多岛弧盆系的形成演化提供了前锋弧发育的岩石学证据及其动力学机制。  相似文献   

西藏班公湖-怒江缝合带中段碰撞后A型花岗岩的时代及其对洋盆闭合时间的约束   总被引：20，自引：0，他引：20  

曲晓明  辛洪波  杜德道  陈华 《地球化学》2012,(1):1-14

近年来地质调查在班公湖-怒江缝合带中段发现了一批A型花岗岩,岩体呈面积不大(＜1 km2)的岩株产出,岩性上分为钾长花岗岩和花岗闪长斑岩两种,侵入白垩系地层中.岩石化学上这些A型花岗岩相对富硅,SiO2含量在68.62％～75.36％之间,全碱含量(K2O+Na2O=8.03％ ～ 9.37％)和全铁含量(FeO(T)...  相似文献   

Age and nature of the late Early Cretaceous Zhaga Formation,northern Tibet: constraints on when the Bangong–Nujiang Neo-Tethys Ocean closed     

《International Geology Review》2012,54(3):342-353

This article reports the depositional environment, provenance, and U–Pb zircon age constraints for the newly identified Zhaga Formation in northern Tibet and uses these to better understand the tectonic evolution of the Bangong–Nujiang suture. One transect across the Zhaga Formation was investigated. The Zhaga Formation is ~2 km thick, dominated by greywacke and conglomerate at the base, basalt and limestone in the middle, and greywacke and shale at the top. Greywacke in the Zhaga Formation typically contains 70–75% quartz, 5% feldspar, 3–5% rock debris, and >15% matrix, with normal grading and convolute bedding, basal flow structures, and distinct Bouma sequences interpreted as bathyal to abyssal turbidites. One rhyolite sample and one greywacke sample from the studied transect were collected for zircon U–Pb dating. The rhyolite yields a concordia age of 118 Ma, and the greywacke yields nine age peaks of 247, 330, 459, 541, 611, 941, 1590, 1871, and 2482 Ma, indicating that the Zhaga Formation formed during the late Early Cretaceous and the provenance of its detritus was the Qiangtang area. These data, combined with the Early Cretaceous ocean islands, indicates that the Bangong–Nujiang Neo-Tethys Ocean must have been open during the late Early Cretaceous. We conclude that the Bangong–Nujiang Neo-Tethys Ocean closed after the late Early Cretaceous and not during the Late Jurassic or the early Early Cretaceous as proposed by previous workers.  相似文献   

Origin and geodynamic environments of the metamorphic sole rocks from the İzmir–Ankara–Erzincan suture zone (Tokat,northern Turkey)     

《International Geology Review》2012,54(15):1839-1855

ABSTRACT

The Late Cretaceous accretionary complex of the ?zmir–Ankara–Erzincan suture zone, near Artova, is composed mainly of peridotites (variably serpentinized), amphibolite, garnet-micaschist, calc-schist, marble, basalt, sandstones, neritic limestones. The metamorphic rocks were interpreted as the metamorphic sole rocks occurring at the base of mantle tectonites, because: (i) amphibolites were observed together with the serpentinized peridotites suggesting their occurrences in the oceanic environment; (ii) foliation in amphibolites and serpentinized peridotites run subparallel to each other; (iii) all these metamorphic rocks and serpentinized peridotites are cross-cut by the unmetamorphosed dolerite dikes with island arc tholeiite-like chemistry. Geochemical characteristics of the amphibolites display enriched mid-ocean ridge basalt (E-MORB)- and ocean island basalt (OIB)-like signatures. The dolerite dikes, on the other hand, yield an island arc tholeiite-like composition. Geothermobarometric investigations of the metamorphic sole rocks suggest that the metamorphic temperature was ~650 ± 30°C and the pressure condition was less than 0.5 GPa. Dating of hornblende grains from amphibolite yielded age values ranging from 139 ± 11 to 157 ± 3.6 Ma (2σ). The oldest weighted average age value is regarded as approximating the timing of the intra-oceanic subduction. These cooling ages were interpreted to be the intra-oceanic subduction/thrusting time of the ?zmir–Ankara–Erzincan oceanic domain.  相似文献   

Characteristics and genesis of diachronous Carboniferous volcano-sedimentary sequences: insights from geochemistry,petrology and U–Pb dating in the North Junggar basin,China     

《International Geology Review》2012,54(4):404-423

ABSTRACT

The subduction of oceanic lithosphere during the Carboniferous Period contributed to the formation of widely distributed subduction-related volcanic rocks within the Junggar basin. These volcanic rock associations contain significant clues for understanding the subduction of the Keramaili oceanic lithosphere and the filling of the remnant oceanic basin. Here, we report regional gravity and magnetic data, petrology, geochemistry, and U–Pb dating for Carboniferous volcanic rocks from the North Junggar basin (NJB). Using samples from well Y-1, we distinguish upper and lower volcanic sequences on the basis of selected geochemical data. An isochronous stratigraphic framework of Carboniferous volcano-sedimentary sequences is then constructed and the petrogenesis of these volcanic rocks is discussed. Finally, we propose an explanation for the genesis of these diachronous Carboniferous volcano-sedimentary sequences. The results show that various volcanic rocks are distributed in different areas of the NJB, and mainly consist of calc-alkaline basalt–andesite–dacite assemblages and alkaline basalt–basaltic andesite–andesite assemblages. The geochemical data also demonstrate a binary nature of the Carboniferous volcanic rocks. In the eastern NJB, the lower and upper volcanic sequences are formed during the early and late Carboniferous, respectively. However, all of these volcano-related sequences in the western of the NJB are formed during the late Carboniferous. These volcano-sedimentary sequences exhibit a ‘ladder-style’ of temporospatial evolution from east to west. The geochemical results also indicate that the upper volcanic rocks include island arc components formed in an extensional setting, whereas the lower volcanic rocks were derived from deep crustal cycling metasomatism by various mantle components in a continental arc environment. Earlier closure of the Keramaili oceanic basin and slab roll-back of the Junggar oceanic lithosphere in eastern versus western Junggar basin led to the formation of these diachronous volcano-sedimentary sequences.  相似文献