新疆巴音沟蛇绿混杂岩带中硅质岩及硅质泥岩的元素地球化学特征及其形成环境     

韩文中  欧阳征健  岳艳  柳益群  周鼎武 《西北地质》2009,42(2):55-63

巴音沟蛇绿混杂岩带中成薄层状产出的硅质岩、硅质泥岩的Si02：55．37％～91．19％,Al2O3含量较高,变化在3．07～17．66,TiO2=0．12～0．8,Al2O3与TiO2具有较好的正相关关系,表明它们含有较高比例的陆源泥质沉积物质。样品经北美页岩标准化的稀土模式呈现无Ce负异常（Ce／Ce^＊=1．03～1．45）的平坦稀土谱型,球粒陨石标准化稀土模式为轻稀土富集,Eu具明显负异常的右倾谱型。均显示与大陆边缘沉积硅质岩、硅质泥岩相似的稀土配分模式。它们的（La／Ce）N=0．62～0．92,V／Y=0．32～8．87,Th／U=2．99～6．45,表明这些硅质岩、硅质泥岩形成于与陆源物质输入密切相关的大陆边缘环境,综合大地构造背景、蛇绿岩带中超基性、基性岩元素地球化学以及年代学分析认为,蛇绿岩就位于早石炭世晚期,形成在大陆裂谷向大洋裂谷转换并形成小洋盆的环境。  相似文献   

北吕宋岛菲律宾活动带蛇绿岩及其上覆浊积岩的放射虫研究新进展     

Keisuke ISHIDA  Shigeyuki SUZUKI  Carla DIMALANTA  Graciano YUMUL JR.  Karlo QUEA?O  Decibel FAUSTINO-ESLAVA  Edanjarlo MARQUEZ  Noelynna RAMOS  Rolando PE?A 《地球学报》2012,33(S1):29-31

The basement of the Philippine Mobile Belt (PMB) is mainly composed of ophiolites that are mostly overlain by Paleogene to Miocene turbidites in central Luzon. To clarify the geological development of the PMB with respect to the initial stage of the arc volcanism (eg. Yumul et al., 2003, 2008; Dimalanta and Yumul, 2003; Suzuki et al., 2011), radiolarian dating was examined in siliceous sediments associated with the ophiolites and turbidites. The samples were collected from sites identified with the Zambales and Montalban ophiolites, basic tuff phyllites in NW Din-galan, and their overlying formations.  相似文献   

西秦岭楔的构造属性及其增生造山过程   总被引：27，自引：17，他引：10  

闫臻  王宗起  李继亮  许志琴  邓晋福 《岩石学报》2012,28(6):1808-1828

西秦岭楔是叠置于早古生代造山作用基础上形成的并插入祁连和昆仑早古生代造山带内部的楔形地质体,以大面积出露三叠系并发育多条蛇绿混杂岩带、大型韧性剪切带、中生代火山-岩浆作用和斑岩-矽卡岩型矿床为典型特征,具有增生造山作用的典型特征。这些蛇绿混杂岩带和岛弧钙碱性火山-岩浆岩的形成时代均具有向南逐渐变年轻的空间演化特征,显示了特提斯洋演化过程中海沟具有向南撤退的基本特征。砂岩碎屑组成以及源区特征研究结果表明,西秦岭楔三叠系形成于活动大陆边缘,其碎屑沉积物来自于古特提斯洋北侧的增生杂岩及岛弧。丰富的岛弧钙碱性火山-岩浆岩和沉积组合以及赋存的斑岩-矽卡岩型矿床,均与东昆仑及南秦岭相一致,呈现出相似的岩石组合类型以及岩石地球化学和同位素地球化学特征。这些事实表明,三叠纪时期,东昆仑、西秦岭以及祁连造山带是一个有机整体,自西向东存在一条三叠纪增生岩浆弧。锆石Hf同位素及岩石地球化学成分结果则表明,该增生岩浆弧部分岩浆来自于俯冲增生杂岩的部分熔融。  相似文献   

新疆伊吾阿勒吞昆多蛇绿混杂岩特征   总被引：1，自引：0，他引：1  

秦彪  张小林  樊文军 《新疆地质》2012,30(2):152-156

前人将唐巴勒-卡拉麦里缝合线置于伊吾县以南哈尔里克山塔水河一线。1993年巴瑞士等在伊吾西北大黑山发现超镁铁岩-镁铁岩洋壳残片,认为卡拉麦里蛇绿岩从伊吾西北大黑山一带向东延伸。2009年笔者参与伊吾县阿尔通盖一带1∶5万区域地质矿产调查工作,于伊吾县以北阿勒吞昆多一带发现阿勒吞昆多蛇绿混杂岩,该蛇绿岩中斜长花岗岩形成于早石炭世((351±6)Ma),大地构造为哈萨克斯坦-准噶尔板块及准噶尔微板块、唐巴勒-卡拉麦里古生代沟弧体系。在研究前人资料基础上,提出阿勒吞昆多蛇绿混杂岩为卡拉麦里蛇绿岩(属唐巴勒-卡拉麦里缝合线)向东延伸部分,唐巴勒-卡拉麦里缝合线(沟弧体系)西起唐巴勒,向东经达拉布特-卡拉麦里-塔克扎勒-大黑山至伊吾县阿勒吞昆多一带,可能延伸至蒙古境内。  相似文献   

新疆西准噶尔拉巴西蛇绿混杂岩带地质特征及其意义     

杨红宾  靳松  陈志彬  张兆祎  谢汝斌  许肖斌  刘树兴 《华北地质》2011,34(3):161-169,178

新疆西准噶尔地区是古生代经过俯冲-增生形成的复合造山带。该地区分布有多条蛇绿岩带,其中的拉巴西蛇绿岩带是比较重要的一条,通过对该蛇绿混杂岩特征的研究,认为该区蛇绿岩尽管受到强烈的多期构造肢解,但根据岩石类型仍能恢复蛇绿岩的原始层序。本文重点讨论了拉巴西蛇绿混杂岩的地球化学特征,认为其形成时代为晚寒武世-中奥陶世,就位时...  相似文献   

Tectonic Zonation and Tectonic Rock Assemblages of Melange in Bangong Lake Area   总被引：1，自引：0，他引：1  

ZHOU Tao  LI Dewei  FENG Minxuan 《《地质学报》英文版》2013,87(Z1):200-200

  相似文献   

内蒙古达茂旗满都拉地区晚古生代板块活动探讨   总被引：7，自引：0，他引：7  

苏新旭  孟二根  张永清 《内蒙古地质》2000,(1)

内蒙古达茂旗满都拉地区位于西伯利亚板块和华北板块的接合带。近年来的1∶ 5万区调识别出本区存在着诸多板块活动遗迹 ,如构造混杂带、洋壳残片、岛弧火山岩、弧后盆地沉积等 ,记录了在石炭纪至二叠纪这段地质时期内本区从拉张、收敛到碰撞等板块活动的全过程。这一成果 ,为研究内蒙古北部地槽区的板块活动历史提供了丰富而可靠的地质资料  相似文献   

Gravity variations along the Southeast Bohol Ophiolite Complex (SEBOC), Central Philippines: Implications on Ophiolite Emplacement     

Jenny Anne L. Barretto  Carla B. Dimalanta and  Graciano P. Yumul  JR   《Island Arc》2000,9(4):575-583

Abstract The basement complex of Bohol Island consists of the Southeast Bohol Ophiolite Complex (SEBOC), Cansiwang Melange and Alicia Schist. The SEBOC is a complete, but dismembered ophiolite with outcrops generally trending northeast– southwest and dipping north-west. The harzburgite units of the SEBOC are almost always observed to be thrusted onto the Cansiwang Melange, which in turn is thrusted onto the Alicia Schist. Bouguer gravity values on Bohol range from about +60 mGal in the west to +120 mGal in the east, in the region to the north-east of the SEBOC outcrops. Based on the present distribution of the SEBOC units and their thrust fault relationship with the Cansiwang Melange and Alicia Schist, it is proposed that the SEBOC was emplaced by onramping towards the south-eastward direction. However, the orientation of the Bouguer highs suggests that the thrusting direction of the ophiolite units is towards the south-west and not towards the south-east.  相似文献   

The Jinshajiang suture zone: tectono-stratigraphic subdivision and revision of age   总被引：2，自引：0，他引：2  

WANG Xiaofeng  Ian Metcalfe  JIAN Ping  HE Longqing  WANG Chuanshang 《中国科学D辑(英文版)》2000,43(1):10-22

Integrated study of rock assemblage, tectonic setting, geochemical feature, fossil contained and isotopic geochronology on the metamorphic mixed bodies, exposed in the Jinshajiang suture zone, suggests that one informal lithostratigraphic unit, the Eaqing Complex, and three tectono-stratigraphic units, the Jinshajiang ophiolitic melange, the Gajinxueshan Group and the Zhongxinrong Group, can be recognized there. It is first pointed out that the redefined Eaqing Complex might represent the Meso- to Neo-Proterozoic remnant metamorphic basement or mi-crocontinental fragment in the Jinshajiang area. The original rocks of it should be older than (1627 ±192) Ma based on the geochronological study. The zircon U-Pb age of plagiogranites within the Jinshajiang ophiolitic assemblage is dated for the first time at (294 ± 3) Ma and (340 ± 3) Ma respectively. The Jinshajiang ophiolite is approximately equivalent to the Ailaoshan ophiolite in the formation age, covering the interval from the Late Devonian to the Carboniferous. Dating of U-Pb age from basalt interbeds indicates that the redefined Gajinxueshan Group and Zhongxinrong Group may be considered Carboniferous to Permian and latest Permian to Middle Triassic in age. In geotectonic terms the Jinshajiang suture zone is thought to be a back-arc basin in the eastern margin of the Paleo-Tethys. This back-arc basin started in the Late Devonian, and formed in the Devonian-Carboniferous. The collision event around the Permian/Triassic boundary to the Middle Triassic led to the closure of the back-arc basin and formation of suture.  相似文献   

吉林延边开山屯地区地层时代的新证据   总被引：11，自引：1，他引：10  

唐克东  赵爱林 《地层学杂志》2007,31(2):141-150

吉林延边开山屯地区古生代地层,在构造地层学研究的基础上,取得一些地层时代的新资料在混杂岩中新发现中二叠世北方型动物群化石;对混杂岩中的花岗岩砾石,测得SHRIMP锆石U-Pb年龄(286.8±5.6Ma),代表岛弧岩浆岩结晶时间;在变蛇绿岩和糜棱岩中采取白云母样品,测得40Ar-39Ar年龄,分别为408Ma和205.7Ma。由此,可以得出开山屯地区地层时代和混杂岩形成与演化的时间表泥盆纪洋壳形成;在中石炭世—中二叠世由南向北的运移过程中,洋壳之上发生硅质和碳酸盐沉积,形成海山;洋壳与由北向南移动的兴凯地块相对运动,二叠纪时向大陆俯冲,在兴凯地块西缘(现代方位)发育岛弧活动,并在中、晚二叠世形成滑塌堆积。可能与晚三叠世的洋壳俯冲作用有关,在兴凯地块前陆边缘发生逆冲作用,形成构造岩片。  相似文献