如何判定俯冲增生杂岩中的高度肢解的洋底高原-海山系统          下载免费PDF全文

肖庆辉  刘勇  程杨  邱瑞照  范玉须  裴斐  杨斌 《沉积与特提斯地质》2021,41(2):152-162

巨型洋底高原或海山系统到达俯冲带发生俯冲以后会在俯冲过程中发生肢解,在增生杂岩带中形成面目全非的小型洋底高原-海山系统的断块或碎片,使得在增生杂岩带中识别古老洋底高原-海山系统变得十分困难。为此,本文提出了基于洋板块地层、岩石学和地球化学联合研究的新方法及其识别标志,重新审定增生杂岩中洋底高原或海山的成因。  相似文献   

Geochronological and geochemical evidence for a Late Ordovician to Silurian arc-back-arc system in the northern Great Xing'an Range,NE China     

Bo Liu  Jia-Fu Chen  Bao-Fu Han  Jun-Lai Liu  Jia-Wei Li 《地学前缘(英文版)》2021,12(1):131-145

The early Paleozoic tectonic evolution of the Xing'an-Mongolian Orogenic Belt is dominated by two oceanic basins on the northwestern and southeastern sides of the Xing'an Block,i.e.,the Xinlin-Xiguitu Ocean and the Nenjiang Ocean.However,the early development of the Nenjiang Ocean remains unclear.Here,we present zircon U-Pb geochronology and whole-rock elemental and Sr-Nd isotopic data on the gabbros in the Xinglong area together with andesitic tuffs and basalts in the Duobaoshan area.LA-ICP-MS zircon U-Pb dating of gabbros and andesitic tuffs yielded crystallization ages of 443-436 Ma and 452-451 Ma,respectively.The Early Silurian Xinglong gabbros show calc-alkaline and E-MORB affinities but they are enriched in LILEs,and depleted in HFSEs,with relatively low U/Th ratios of 0.18-0.36 andεNd(t)values of-1.6 to+0.5.These geochemical features suggest that the gabbros might originate from a mantle wedge modified by pelagic sediment-derived melts,consistent with a back-arc basin setting.By contrast,the andesitic tuffs are characterized by high MgO(>5 wt.%),Cr(138-200 ppm),and Ni(65-110 ppm)contents,and can be termed as high-Mg andesites.Their low Sr/Y ratios of 15.98-17.15 and U/Th values of 0.24-0.25 and moderate(La/Sm)_n values of 3.07-3.26 are similar to those from the Setouchi Volcanic Belt(SW Japan),and are thought to be derived from partial melting of subducted sediments,and subsequent melt-mantle interaction.The Duobaoshan basalts have high Nb(8.44-10.30 ppm)and TiO2 contents(1.17-1.60 wt.%),typical of Nb-enriched basalts.They are slightly younger than regional adakitic rocks and have positiveεNd(t)values of+5.2 to+5.7 and are interpreted to be generated by partial melting of a depleted mantle source metasomatized by earlier adakitic melts.Synthesized with coeval arc-related igneous rocks from the southeastern Xing'an Block,we propose that the Duobaoshan high-Mg andesitic tuffs and Nbenriched basalts are parts of the Late Ordovician and Silurian Sonid Zuoqi-Duobaoshan arc belt,and they were formed by the northwestern subduction of the Nenjiang Ocean.Such a subduction beneath the integrated Xing'an-Erguna Block also gave rise to the East Ujimqin-Xinglong igneous belt in a continental back-arc basin setting.Our new data support an early Paleozoic arc-back-arc model in the northern Great Xing'an Range.  相似文献   

非洲东北部阿拉伯-努比亚地盾(ANS)构造演化与金成矿作用     

魏浩 《地质与勘探》2015,51(2):283-394

阿拉伯-努比亚地盾(Arabian Nubian Shield,简称ANS)是900~550Ma期间冈瓦纳超大陆汇聚过程中形成的增生造山带,这一造山过程也被称为是泛非造山运动。它记录了一个长期的造山演化历史,经历了从大洋俯冲、岛弧形成及弧后的岩浆作用到大陆板块碰撞地体的拼合,再到新生地壳的逃逸构造、走滑剪切、张性断裂一系列的构造演化过程。这个演化可以分为四个阶段:(1)洋盆形成阶段(870~800 Ma);(2)洋壳俯冲阶段(800~670 Ma);(3)造山阶段(750~550 Ma);(4)后造山阶段(550 Ma~三叠纪),其中后三个阶段都有金的富集成矿作用。洋壳俯冲阶段的金矿化主要赋存在Algoma型含铁建造层(BIF)、凝灰质变质碎屑岩,以及火山成因的块状硫化物矿床内。造山阶段的主要金矿化类型为含金石英-碳酸盐脉状金矿化、与斑岩铜矿化有关的金矿化,以及与辉长岩类岩体有关的含金石英脉状矿化。与后造山阶段有关的金矿化以少量浸染状、网脉状并伴有Sn-W-Ta-Nb矿化的石英脉为特征。目前在ANS中发现了大量金矿床或矿点,它们具有各种不同的成因类型。根据构造背景及赋矿围岩,ANS原生金矿化可以划分为三类:(1)与火山沉积序列有关的金矿化,包括VMS型、浅成热液型;(2)空间分布上与碳酸盐化蛇绿岩带相关的金矿化;(3)与后造山或造山晚期闪长岩-花岗岩岩体或次火山岩有关的金矿化。  相似文献   

海洋三维遥感与海洋剖面激光雷达     

唐军武  陈戈  陈卫标  赵朝方  贺岩  吴松华  刘秉义  毛志华  何惠馨  杨杰  陈树果  胡连波  何兴道  史久林  郑永超  刘建强  林明森  吴立新  郭华东  蒋兴伟  潘德炉  顾逸东 《遥感学报》2021,25(1):460-500

本文从海洋与气候变化等重大前沿科学与应用对空间海洋观测系统的需求出发,基于当前国内外空间激光技术水平与前期海洋激光遥感的探索,提出了海洋遥感从二维向三维发展的紧迫性,并将海洋剖面探测激光雷达作为未来“海洋三维遥感”的主要技术手段。本文对近50年国内外激光海洋剖面探测技术的理论与应用、基础性关键探测机理问题,尤其是近10年来的试验性探索及其在多个海洋科学问题中的应用进行了综述。结合中国自主“观澜号”海洋科学卫星计划中海洋剖面探测激光雷达的系统论证与指标要求,提出了未来海洋剖面探测激光雷达发展路线图建议以及中国有望率先在空间海洋剖面激光探测领域取得突破的设想。  相似文献   

Permian Tectonic Evolution in Southwestern Khanka Massif: Evidence from Zircon U‐Pb Chronology,Hf isotope and Geochemistry of Gabbro and Diorite   总被引：8，自引：0，他引：8  

CAO Huahu  XU Wenliang  PEI Fuping  ZHANG Xingzhou 《《地质学报》英文版》2011,85(6):1390-1402

Laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS) zircon U-Pb dating and geochemical data for the Permian gabbros and diorites in the Hunchun area are presented to constrain the regional tectonic evolution in the study area. Zircons from gabbro and diorite are euhedral-subhedral in shape and display fine-scale oscillatory zoning as well as high Th/U ratios (0.26–1.22), implying their magmatic origin. The dating results indicate that the gabbro and diorite formed in the Early Permian (282±2 Ma) and in the Late Permian (255±3 Ma), respectively. In addition, the captured zircons with the weighted mean age of 279±4 Ma are also found in the diorite, consistent with the formation age of the gabbro within uncertainty. The gabbros belong chemically to low-K tholeiitic series, and are characterized by low rare earth element (REE) abundances, flat REE pattern, weak positive Eu anomalies (δEu), and depletion in high field strength elements (HFSEs, Nb, Ta, and Ti), similar to the high-aluminum basalts from island arc setting. Initial Hf isotopic ratios of zircons from the gabbro range from +7.63 to +14.6, suggesting that its primary magma could be mainly derived from partial melting of a depleted lithospheric mantle. The diorites belong to middle K calc-alkaline series. Compared with the gabbros, the diorites have higher REE abundance, weak negative Eu anomalies, and more depletion in HFSEs (Nb, Ta, and Ti), similar chemically to the volcanic rocks from an active continental margin setting. Initial Hf isotopic ratios and Hf two-stage model ages of zircons from the diorite range from +11.22 to +14.17 and from 424 to 692 Ma, respectively, suggesting that its primary magma could be mainly derived from partial melting of the Early Paleozoic and/or Neoproterozoic accretted lower crust. Taken together, it is suggested that geochemical variations from the Early Permian gabbros to the Late Permian diorites reveal that the subduction of the Paleo-Asian oceanic plate beneath the Khanka Massif and collision between the arc and continent (Khanka Massif) happened in the late stage of the Late Paleozoic.  相似文献   

内蒙古东乌旗宝力高庙组地层划分及其同位素年代学研究   总被引：11，自引：0，他引：11  

辛后田  滕学建  程银行 《华北地质》2011,34(1):1-9

在1/5万内蒙古东乌旗狠麦温都尔地区的矿产远景调查工作中,首次按照岩性组合的差异,将宝力高庙组划分出以安山岩、安山质火山碎屑岩夹砂砾岩为主和以酸性火山岩-火山碎屑岩、炭质板岩、河流相砂砾岩为主的上、下段.在其中分别采集地层中的流纹岩、英安质晶屑凝灰岩和安山岩夹层样品,挑选其中的锆石进行U-Pb SHRIMP同位素测年,...  相似文献   

上海地学研究：从长江口到深海——中国科学院院士汪品先教授接受本刊专访     

《上海国土资源》2011,32(3):1-6

2011年8月30日下午,本刊主编、上海市地质调查研究院总工程师严学新教授,本刊编辑部主任、上海市地质调查研究院总工程师办公室副主任龚士良教授,在同济大学海洋与地球科学学院杨守业教授的陪同下,拜访了中国科学院院士、同济大学海洋与地球科学学院汪品先教授,并作了专题访谈。  相似文献   

卫星高度计资料在三维海温和盐度数值预报中的应用   总被引：2，自引：0，他引：2  

李云  万莉颖  刘钦政 《海洋学报》2011,33(6):64-72

随着卫星遥感观测技术的发展,越来越多的卫星观测资料被应用于数值模式的同化研究中.基于国家海洋环境预报中心西北太平洋三维湿盐流预报系统,利用法国CLS中心的沿轨高度计资料的海表面高度异常的融合数据,结合基于三维变分的OVALS(ocean variational analysis system)同化系统,在垂向将海面高度...  相似文献   

Evolution of a coastal upwelling event during summer 2004 in the southern Taiwan Strait   总被引：3，自引：0，他引：3  

ZHANG Caiyun  HONG Huasheng  HU Chuanmin  SHANG Shaoling 《海洋学报(英文版)》2011,30(1):1-6

A coastal upwelling event in the southern Taiwan Strait (STWS) was investigated using intensive cruise surveys (four repeated transects in a month) and satellite data in July and early August 2004.The extensive upwelling-associated surface cold water was first observed in early July (～2.0×10 4 km 2) along the STWS coast.Then,the cold surface water reduced in size by ～50% with decreased chlorophyll concentrations after 15 days,indicating the weakening of the upwelling event.At the end of July,the cold surface water disappeared.The temporal variations of the surface cold water and the 3-D hydrography around Dongshan Island are thought to be mainly attributed to the weakened upwelling-favorable southwestern wind,the asymmetric spatial structure of the wind field and the intrusion of warm water from the northern South China Sea.  相似文献   

Editorial: Reflections from Ireland     

Valerie Anne Cummins  Kathrin Kopke 《Marine Policy》2011

Responses of governance systems to change in coastal and marine ecosystems vary from country to country around the globe. Lessons can be learned from country specific case studies, as national governments strive to adapt and respond to issues of concern. This short paper highlights the benefits of a country-specific, special edition of Marine Policy, with a focus on Ireland. Despite the uniqueness of socio-ecological setting, many of the issues faced by policy makers in Ireland, such as the reconciliation of economic development and conservation needs, are shared elsewhere. This special edition was produced at the end of the ‘Celtic Tiger’ in Ireland. As a result, it reflects an era when economic development was very much a priority. The same period represented an unparalleled investment in marine science since the foundation of the State in 1922. Despite this, the papers in the Special Edition point to varying degrees of progress in policy integration and implementation. Papers covering a range of sectors (fisheries, ocean energy, conservation and fisheries) and disciplines (economics, science and management) will be of interest to academics, policy makers, students and practitioners of marine policy.  相似文献