西昆仑库地混杂岩带中深海浊积岩的浊积相划分及其特征   总被引：9，自引：3，他引：9  

方爱民  侯泉林  李继亮  郝杰  肖文交  周辉 《地质科学》2003,38(1):1-12

西昆仑库地混杂岩带中发育一套深海浊积岩。本文在系统的沉积相分析基础上,识别并划分出本区浊积岩的7类浊积相及14种亚相,结合其成因分别对各浊积相(亚相)的沉积特征、垂向分布规律进行了总结与描述。此外,垂向上还识别出3种浊积相组合,文中对其沉积序列特征及其所代表的环境意义进行了阐述。结合其它资料,探讨了这套浊流沉积的沉积环境,认为它形成于位于消减带和海沟之间的弧前盆地环境。  相似文献   

西昆仑北缘新元古代片麻状花岗岩锆石SHRIMP年龄及其意义   总被引：19，自引：0，他引：19  

张传林  杨淳  沈加林  王爱国  赵宇  董永观  郭坤一 《地质论评》2003,49(3):239-244

在西昆仑北缘早前寒武纪变质地层中,笔者等识别出大量不同时代的片麻状花岗岩,其中包括新元古代片麻状花岗岩。获得最新的新元古代片麻状花岗岩的单颗粒锆石SHRIMP年龄为815±57Ma,片麻状花岗岩的岩石学特征反映它们形成于裂解构造背景,结合对区域上新元古代地层及中元古代末期构造事件的研究,笔者认为新元古代片麻状花岗岩反映了古塔里木板块作为Rodinia超大陆一员发生裂解的时间,这对研究古塔里木板块在Rodinia超大陆中的位置及中国Rodinia超大陆裂解的研究提供了重要的地质依据。  相似文献   

Caledonian Low-Temperature Granulite-Facies Metamorphism in the West Kunlun Orogenic Belt—SHRIMP Chronological Evidence from Zircon     

Zhang Chuanlin  Shen Jialin  Wang Aiguo  Zhao Yu  Guo Kunyi  Li Chunhai 《中国地球化学学报》2003,22(4):345-351

The West Kunlun orogenic belt is located at the conjunction of the paleo-Asian tectonic system and the Tethys tectonic system. Petrological and mineralogical studies of the Early Cambrian metamorphic surface crust in this region have shown that in case the metamorphism reached low-temperature granulate facies, the typical mineral assemblage is biotite-garnet-silimanite-K feldspar-plagioclase-quartz. The peak metamorphic temperatures are within the range of 720–740°C and the pressure is 0.6 GPa ±. Three types of metamorphic zircon have been detected in the metamorphic rocks: the complex inclusion-bearing type ; the early relic zircon inclusion-bearing type; and the inclusion-free type. SHRIMP age determination of these three types of metamorphic zircon have revealed that these zircons were formed principally during 400–460 Ma, indicating that pre-Cambrian metamorphic surface crust rocks underwent low-temperature granulite facies metamorphism during the Caledonian. In combination with the geological characteristics of this region, it is considered that when the oceanic basin was closed, there occurred intense intracontinental subduction (type A), bringing part of the Early Cambrian metamorphic basement in this region downwards to the lower crust. Meanwhile, there were accompanied with tectonic deformation at deep levels and medium- to high-grade metamorphism. This study provided important chronological and mineralogical evidence for the exploration of the evolutionary mechanism and process of the West Kunlun Early Paleozoic. Part of the results from the research project “ Research on the West Kunlun pre-Cambrian tectonic events” under the program “ Research on the important geological problems of China’ s pre-Cambrian” (No. 200113900070) sponsored by the China National Geological Surveying Bureau.  相似文献   

东昆仑造山带花岗岩类Pb-Sr-Nd-O同位素特征   总被引：19，自引：1，他引：19  

刘成东  莫宣学  罗照华  喻学惠  谌宏伟  李述为  赵欣 《地球学报》2003,24(6):584-588

本文报道了东昆仑造山带三叠纪辉长岩、花岗岩类及其包裹体的Pb、Sr、Nd和O同位素组成。东昆仑造山带花岗质岩石全岩和长石Pb同位素组成相差不大，具明显的造山带Pb同位素特征；Sr同位素初始值(ISr)变化于0．70144～0．70972之间，暗示幔源成因；εNd值变化于-4．49939～-9．19258之间，具壳源成因特点；Nd同位素模式年龄(tDM)在1．38～1．761Ga之间，与中元古代变质岩相当；O同位素组成变化范围7．8～9．5，表明花岗岩类成岩物质主要来自地壳。综合岩石的同位素组成，结合矿物学、岩石地球化学的研究，表明花岗岩浆主要起源于地壳，但与来自地幔的基性岩浆曾发生过混合作用，从而导致同位素组成趋于一致。  相似文献   

2001年11月14日昆仑山口西8.1级地震前地震活动性异常及其思考s   总被引：7，自引：0，他引：7       下载免费PDF全文

刘蒲雄  郑大林  车时  潘怀文  刘桂萍  杨立明 《地震学报》2003,25(2):205-210

2001年11月14日在昆仑山口西发生了8.1级地震，震中位置为90.9E、36.2N．分析表明，8.1级地震前一些主要地震活动性异常都出现了，例如空区、条带、增强、平静和震群等，且与7级大震比较，这些前兆图象的演变具有类似的过程，所不同的是8.1级地震的前兆地震活动图象涉及的区域范围更大、地震震级更高，这为特大地震的前兆识别和预报提供了依据．最后回顾了对这次大震的粗略预测，并讨论了有关大震预测的某些问题．   相似文献   

东部欠发达地区特征,原因及对策——以沧州市为例     

孟斌 《地域研究与开发》1997,16(1):58-61

对东部欠发达地区的特征，原因进行分析和研究，不仅有助于这些地区经济早日腾飞，对中西部地区的开发与发展也会有较大的参考价值。本文以河北省沧州市为例，分析了东部欠发达地区的特征和原因，并在此基础上提出东部欠发达地区经济发展的对策。  相似文献   

中国东部中新生代盆地成因及其地球动力学   总被引：9，自引：1，他引：9  

孙加鹏  杨宝俊 《世界地质》1997,16(3):1-6

中国东部大兴安岭－太行山－武陵山重力梯度带一线以东至太平洋西岩，大陆连缘中新生代盆地系的形成，中生代岩浆活动，盆地基本特征同Ｍｏｈｏ、岩石圈和软流圈及上地幔基本特征的内在联系等都表明，它们在时空和成因上有一定联系，可以纳入同一地球动力学过程之中，这种动力学机制可能与岩石圈界，地壳底界的拆离作用有关。  相似文献   

A traverse through the western Kunlun (Xinjiang,China): tentative geodynamic implications for the Paleozoic and Mesozoic   总被引：13，自引：0，他引：13  

F. Mattern  W. Schneider  Y. Li  X. Li 《International Journal of Earth Sciences》1996,85(4):705-722

The northern part of the western Kunlun (southern margin of the Tarim basin) represents a Sinian rifted margin. To the south of this margin, the Sinian to Paleozoic Proto-Tethys Ocean formed. South-directed subduction of this ocean, beneath the continental southern Kunlun block during the Paleozoic, resulted in the collision between the northern and southern Kunlun blocks during the Devonian. The northern part of the Paleo-Tethys Ocean, located to the south of the southern Kunlun, was subducted to the north beneath the southern Kunlun during the Late Paleozoic to Early Mesozoic. This caused the formation of a subduction-accretion complex, including a sizeable accretionary wedge to the south of the southern Kunlun. A microcontinent (or oceanic plateau?), which we refer to as “Uygur terrane,” collided with the subduction complex during the Late Triassic. Both elements together represent the Kara-Kunlun. Final closure of the Paleo-Tethys Ocean took place during the Early Jurassic when the next southerly located continental block collided with the Kara-Kunlun area. From at least the Late Paleozoic to the Early Jurassic, the Tarim basin must be considered a back-arc region. The Kengxiwar lineament, which “connects” the Karakorum fault in the west and the Ruogiang-Xingxingxia/Altyn-Tagh fault zone in the east, shows signs of a polyphase strike-slip fault along which dextral and sinistral shearing occurred.  相似文献   

腾冲火山区S波速度结构接收函数反演   总被引：13，自引：0，他引：13       下载免费PDF全文

郝平  傅征祥  田勤俭  刘杰  刘桂萍 《地震学报》2004,26(1):30-37

腾冲火山区临近印度板块与欧亚板块碰撞、俯冲的边界，火山活动与构造环境关系密切．采用远震接收函数反演的方法揭示了该区域的深部结构特征. 结果显示, 腾冲火山区S波低速结构明显受到NE向大盈江断裂的影响，断裂的南部存在明显的S波低速构，断裂的北部低速结构不十分明显．火山区存在浅部的低速结构，低速结构与地震活动性存在对应关系．证实了低速结构是火山区热活动的直接因素, 并认为腾冲火山区存在再次活动的基本条件．   相似文献   

东昆仑阿尔格山二叠纪生物礁的特征及其古地理古气候的意义          下载免费PDF全文

范嘉松  田树刚  吴亚生 《古地理学报》2004,6(3):329-338

东昆仑山脉西段二叠纪生物礁由早二叠世、中二叠世的栖霞期和茅口期三个层位组成，早二叠世的礁和中二叠世栖霞期的礁是我国首次发现的，填补了我国二叠纪礁的空白。早二叠世礁的时代相当于阿赛尔-萨克马尔-阿丁斯克期，主要表现为海绵礁、苔藓虫礁和Shamovella(Tubiphytes)-古石孔藻礁。但缺失由Palaeoaplysina组成的礁。中二叠世栖霞期的礁表现为海绵-苔藓虫礁、Shamovella-苔藓虫礁和叶状藻礁。中二叠世茅口期的礁与栖霞期的礁类型基本一致。阿尔格山礁是塔吉克斯坦-喀拉昆仑地体的一个部分，该地体位于南纬30°以北的东特提斯海内。此处的二叠纪礁由各种生物组成，包括珊瑚海绵、苔藓虫、Shamovella.古石孔藻、棘皮类、有孔虫、叶状藻、粗枝藻以及腹足类等，推测该礁形成于温暖和炎热气候条件下的暖水内，而非冷水礁。  相似文献