Ophiolites from the Mianlue Suture in the Southern Qinling and Their Relationship with the Eastern Paleotethys Evolution     

LAI Shaocong  ZHANG Guowei  LI SanzhongKey Laboratory of Continental Dynamics  Ministry of Education  Department of Geology  Northwest University  Xi''an  Shaanxi  College of Earth Science  Ocean University of Qingdao  Qingdao  Shandong 《《地质学报》英文版》2004,78(1)

The Mianlue suture extends from Derni-Nanping-Pipasi-Kangxian to the Lueyang-Mianxian area, then traverses the Bashan arcuate structure eastward to the Huashan region, and finally to the Qingshuihe area of the southern Dabie Mountains. From east to west, with a length of over 1500 km, the ophiolitic melange associations are distributed discontinuously along the suture. The rock assemblages include ophiolite, island-arc and oceanic island rock series, indicating that there existed a suture zone and a vanished paleo-ocean basin. The Mianliie paleo-ocean basin experienced its main expansion and formation process during the Carboniferous-Permian and closed totally in the Triassic. It belongs to the northern branch of the eastern paleotethys, separated from the northern margin of the Yangtze block under the paleotethys mantle dynamic system.  相似文献   

Cretaceous volcanic rocks of the South Tethyan suture zone, Pakistan: implications for the Réunion hotspot and Deccan Traps   总被引：1，自引：0，他引：1  

J.J. Mahoney  R.A. DuncanW. Khan  E. GnosG.R. McCormick 《Earth and Planetary Science Letters》2002,203(1):295-310

The location, ages, and geochemical characteristics of marine volcanic rocks preserved in the South Tethyan suture zone of Pakistan suggest that the Réunion hotspot was active off northwestern Greater India well before the emplacement, far to the south, of the Deccan flood basalts, the great bulk of which were erupted at 65-66 Ma and are widely believed to be associated with the hotspot’s plume-head phase. Most of the suture zone samples have Nd-Pb-Sr isotopic ratios (e.g. age-corrected ?_Nd(t)=+3.0 to +4.6) close to those expected for modern-type Réunion source mantle in the Late Cretaceous, and their incompatible element patterns resemble those of recent Réunion shield lavas. ⁴⁰Ar-³⁹Ar incremental heating yields ages of 73.4-72.0 Ma. Nevertheless, unless even older ages are discovered among the suture zone rocks, a pre-Deccan marine phase of Réunion hotspot activity on the Tethyan side of Greater India can be accommodated within the framework of the plume-head model.  相似文献   

Was there a wind-driven Tethys circumglobal current in the Late Cretaceous?     

N.M.M. Cousin-Rittemard  H.A. DijkstraT. Zwagers 《Earth and Planetary Science Letters》2002,203(2):741-753

The problem of the existence of a Tethys circumglobal current (TCC) in the Late Cretaceous continental geometry (Campanian) is addressed. Within an ocean model which is expected to strongly overestimate the wind-driven TCC volume transport, a relatively weak TCC is found for the reconstructed Campanian paleogeography used. As a measure of the strength of the TCC, a circumglobal flow index is introduced. This index is based on volume fluxes through meridional sections within the equatorial part of the domain. The impact of changes in the paleogeography on the TCC is considered by computing steady flows for different shapes of Eurasia. The results on the extent of Eurasia such that a strong TCC appears provide support that no strong wind-driven TCC has existed during the Campanian.  相似文献   

兰州马衔山北缘断裂带古地震初步研究   总被引：4，自引：0，他引：4       下载免费PDF全文

袁道阳  贾亚会  才树华  刘百篪  刘小龙  王永成 《地震工程学报》2002,24(1):27-33

兰州马衔山北缘断裂带为一条全新世活动断裂 ,大致由 4条次级断裂段组成 .沿断裂带发现了多期古地震事件 ,其活动具有时空不均匀性 .其中东段的马衔山段可以确定 2次古地震事件 ,距今 5850± 50 0aB .P .,2 0 60± 42 0aB .P .,复发间隔约 380 0a ;震级 7～ 7.5级左右 .中段的七道梁段发现 2次古地震事件 ,距今 1 682 0± 80aB .P .,1 0 80 0± 1 40aB .P ..西段的雾宿山咸水沟段可以确定一次古地震事件 ,其年代为 1 2 45± 560aB .P .,结合史料考证结果 ,认为就是 1 1 2 5年兰州 7级地震 .从古地震活动年代及复发间隔分析 ,马衔山北缘断裂带未来的强震危险段应为东段的马衔山段和西段的雾宿山咸水沟段 .  相似文献   

北大别黄土岭麻粒岩锆石U—Pb离子探针定年   总被引：28，自引：6，他引：28  

吴元保  陈道公  夏群科  Etienne DELOULE  程昊 《岩石学报》2002,18(3):378-382

阴极发光显微结构分析表明 ,北大别黄土岭麻粒岩中存在三种类型的锆石 :原岩锆石、麻粒岩相锆石和残留锆石。对它们分别进行离子探针定年 ,得到黄土岭麻粒岩的原岩年龄约为 2 70 0 Ma、麻粒岩相变质事件的年龄为 2 0 5 2± 10 0 Ma、残留锆石的年龄为约 3.4 Ga。以上研究表明黄土岭麻粒岩为残存的扬子板块的结晶基底 ,而约 3.4 Ga残留锆石的发现 ,则首次证明大别山地区存在古太古代的陆壳物质  相似文献   

西藏南部硅质岩的特征及相关问题探讨   总被引：1，自引：0，他引：1  

付伟周永章  杨志军聂凤军  何俊国李文 《地质通报》2007,26(4):492-501

西藏南部广泛发育中生代古海洋沉积硅质岩,在空间上集中分布于雅鲁藏布江缝合带和喜马拉雅沉积带,呈东西向条带状分布,断断续续延伸达数千公里。可大致厘定出3条硅质岩带:缝合带蛇绿岩北侧早白垩世硅质岩带、缝合带蛇绿岩南侧三叠纪至白垩纪硅质岩带和喜马拉雅沉积带白垩纪硅质岩带,产出块状、层状、角砾状和结核状4种类型的硅质岩。在沉积建造特征上,缝合带蛇绿岩北侧硅质岩带以蛇绿岩-硅质岩建造为主;缝合带蛇绿岩南侧硅质岩带主要以火山岩-硅质岩建造和改造型硅质岩建造为主;喜马拉雅沉积带硅质岩则以浊积岩-硅质岩建造为特征。藏南硅质岩具有重要的研究意义,其薄弱环节和科学问题主要包括:硅质岩的成因问题、硅质岩的微组构问题、硅质岩中的古海洋沉积事件信息、硅质岩对沉积环境的指相意义等。  相似文献   

深海相中的砂质碎屑流沉积--以西藏特提斯喜马拉雅侏罗-白垩系为例   总被引：4，自引：1，他引：3  

李祥辉  王成善  胡修棉 《矿物岩石》2000,20(1)

阐述了砂质碎屑流沉积特征、研究现状及其与其他深海碎屑沉积的区别 ,认为西藏特提斯喜马拉雅上侏罗统 -下白垩统深海沉积背景下的块状砂岩具有砂质碎屑流沉积性质 ,指出深海相中的块状砂岩可以预测。  相似文献   

BIOGEOGRAPHIC RELATIONS OF THE JURASSIC PECTINOIDA AND OSTREOIDA (BIVALVIA) BETWEEN TANGGULA AND OTHER AREAS   总被引：2，自引：0，他引：2  

Sha Jingeng 《地学前缘》2000,(Z1)

BIOGEOGRAPHIC RELATIONS OF THE JURASSIC PECTINOIDA AND OSTREOIDA (BIVALVIA) BETWEEN TANGGULA AND OTHER AREAS  相似文献   

FORMATION AND EUOLUTION OF TETHYS IN THE TIBETAN PLATEAU     

Pan YushengWT  ”BX 《地学前缘》2000,(Z1)

FORMATION AND EUOLUTION OF TETHYS IN THE TIBETAN PLATEAU  相似文献   

羌塘盆地性质及构造演化   总被引：20，自引：1，他引：19  

黄继钧 《地质力学学报》2000,6(4):58-66

羌塘盆地位于班公湖-怒江缝合带和西金乌兰-金沙江缝合带之间,是一沉积盆地,分为羌南坳陷、中央隆起、羌北坳陷。盆地形成演化受特提斯构造带地球动力学控制。对盆地地层格架和区内碎屑岩的主要矿物成分、化学成分、微量元素以及火成岩化学成分的分析表明,羌塘盆地系不同类型盆地叠置而成的多旋回叠合盆地。晚古生代至中生代初为克拉通裂谷盆地、晚三叠世-侏罗纪为前陆盆地、白垩纪-第四纪为挤压抬升阶段,形成山间断陷盆地。   相似文献