首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 93 毫秒
1.
金沙江(-哀牢山)弧盆系是西南三江多岛弧盆系的重要组成部分,恢复其时空格架及其形成演化过程对理解古特提斯多岛弧盆系的时空格局具有重要意义。根据新的地质调查资料、研究成果并结合分析数据,系统总结了金沙江弧盆系不同构造单元的物质组成及其构造属性,讨论了其构造演化过程及其对VMS型矿床的控制作用。金沙江洋壳发育时限主要为晚志留世—二叠纪,古洋壳地幔受到了早期俯冲带物质富集组分的影响,主体形成于弧后盆地的构造环境。江达-德钦-维西岩浆弧为一复杂的陆缘弧,经历了俯冲消减(300~260 Ma)、早碰撞聚合(255~250 Ma)、同碰撞伸展(249~237 Ma)和晚碰撞造山(236~212 Ma)等构造事件叠加改造,形成了不同类型、不同环境的岩浆活动及其盆地。金沙江带新发现的贡觉榴辉岩、维西退变榴辉岩等高压变质带,为恢复金沙江古特提斯洋的俯冲-碰撞造山的复杂演化过程提供了重要证据。在此基础上,结合区域地质资料,构建了金沙江弧盆系的演化历史,认为经历了晚志留世—早二叠世金沙江(-哀牢山)弧后洋盆扩张、早二叠世晚期—晚二叠世洋壳俯冲消减、早三叠世—晚三叠世弧-陆碰撞造山与盆-山转换、晚三叠世末期后碰撞陆内造山至陆内汇聚-走滑转换等阶段的演化过程,每个阶段控制着不同类型的VMS型矿床。  相似文献   

2.
青藏高原中的古特提斯体制与增生造山作用   总被引:28,自引:12,他引:16  
青藏高原古特提斯体系的特征表现为古特提斯洋盆中多条状地体的存在,多俯冲、多岛弧增生体系的形成和多地体汇聚、碰撞造山的动力学环境,其构架包括4条代表古特提斯洋壳残片的蛇绿岩或蛇绿混杂岩(昆南-阿尼玛卿蛇绿岩带、金沙江-哀牢山-松马蛇绿岩带、羌中-澜沧江-昌宁-孟连蛇绿岩带和松多蛇绿岩带)、5条火山岩浆岛弧带(布尔汗布达岛弧岩浆带、义敦火山岩浆岛弧带、江达-绿春火山岛弧带、东达山-云县火山岛弧带和左贡-临沧岛弧-碰撞岩浆带)、4个陆块或地体(松潘-甘孜地体、羌北-昌都-思茅地体、羌南-保山地体)、3条洋壳深俯冲形成的高压-超高压变质带(金沙江得荣高压变质带、龙木错-双湖高压变质带、松多高(超)压变质带),以及5条弧前增生楔或增生杂岩(西秦岭增生楔、巴颜喀拉-松潘-甘孜增生楔、金沙江增生楔、双湖-聂荣-吉塘-临沧增生楔、松多增生杂岩)。古特提斯洋盆的俯冲增生造山作用普遍存在于青藏高原古特提斯复合造山体中,构成与多条古特提斯蛇绿岩带(缝合带)相伴随的俯冲增生杂岩带(链)。古特提斯俯冲增生杂岩带包括由弧前强烈变形的沉积增生楔、以及高压变质岩、岛弧岩浆岩、蛇绿岩和外来岩块组成的混杂体,代表在洋盆俯冲过程中的活动陆缘的地壳增生。  相似文献   

3.
三江昌宁-孟连带原-古特提斯构造演化   总被引:4,自引:0,他引:4  
昌宁-孟连特提斯洋的构造演化及其原特提斯与古特提斯的转换方式一直是青藏高原及邻区基础地质研究中最热门的科学问题之一.根据新的地质调查资料、研究成果并结合分析数据,系统总结了三江造山系不同构造单元地质特征,讨论了昌宁-孟连特提斯洋早古生代-晚古生代的构造演化历史.通过对不同构造单元时空结构的剖析和对相关岩浆、沉积及变质作用记录的分析,认为昌宁-孟连结合带内共存原特提斯与古特提斯洋壳残余,临沧-勐海一带发育一条早古生代岩浆弧带,前人所划基底岩系"澜沧岩群"应为昌宁-孟连特提斯洋东向俯冲消减形成的早古生代构造增生杂岩,滇西地区榴辉岩带很可能代表了俯冲增生杂岩带发生了深俯冲,由于弧-陆碰撞而迅速折返就位,这一系列新资料及新认识表明昌宁-孟连结合带所代表的特提斯洋在早古生代至晚古生代很可能是一个连续演化的大洋.在此基础上,结合区域地质资料,构建了三江造山系特提斯洋演化的时空格架及演化历史,认为其经历了早古生代原特提斯大洋扩张、早古生代中晚期-晚古生代特提斯俯冲消减与岛弧带形成、晚二叠世末-早三叠世主碰撞汇聚、晚三叠世晚碰撞造山与盆山转换等阶段.   相似文献   

4.
西南三江地区洋板块地层特征及构造演化   总被引:3,自引:3,他引:0  
以大地构造研究为主导,初步梳理了三江地区洋板块地层系统的分布及其构造演化规律。本文阐述了三江地区经历原-古特提斯大洋连续演化、分阶段拼贴增生至最终俯冲消亡的地质演化历程。甘孜-理塘弧后洋盆于早石炭世打开,二叠纪—中三叠世进入顶峰扩张期,晚三叠世洋盆萎缩引起向西俯冲,最终在晚三叠世末局部地区保留残留海。哀牢山弧后洋盆不晚于早石炭世形成,早石炭世—早二叠世整体扩张发育,早二叠世末或晚二叠世初开始向西俯冲,晚三叠世最终完全关闭。金沙江洋盆早石炭世时已扩张成洋,到早二叠世晚期开始俯冲,石炭纪—早二叠世早期是金沙江洋盆扩张的主体时期,早二叠世晚期至早、中三叠世俯冲消亡。澜沧江弧后洋盆中晚泥盆世开始扩张,在石炭纪—早二叠世发育为成熟洋盆,早二叠世晚期洋内俯冲形成洋内弧,晚二叠世—早、中三叠世双向俯冲消亡。昌宁-孟连洋为特提斯洋主带,具有原-古特提斯洋连续演化的地质记录,晚奥陶世开始向东俯冲消减,二叠纪末、早三叠世发生弧-陆碰撞作用,昌宁-孟连洋盆闭合。  相似文献   

5.
秦岭造山带板缘裂解与拼合过程及动力学分析   总被引:1,自引:0,他引:1       下载免费PDF全文
秦岭造山带与原特提斯洋、占特提斯洋扩张作用同步,于震旦世至早奥陶世阿伦尼克期、泥盆纪至早三叠世分别以商丹洋和勉略洋(海)为中心发生两次洋、陆扩张运动,实现了华北板块与扬子板块之间以及各自板缘带的全面裂解破碎,从而形成复杂而不规则的板缘构造带。在主造山期继商丹古洋盆和勉略古洋(海)盆扩张之后分别于早奥陶世、早三叠世晚期开始转变为俯冲消减,并先后于晚古生代末期和中、晚二叠世实现拼合造由,由于商丹古洋壳俯冲消减受到勉略古洋盆同时期的扩张作用影响,秦岭造山带之中的华北板块与扬子板块碰撞过程首先表现为板缘区南方的微地块(或微板块)与北方华北板  相似文献   

6.
笔者根据国内外研究进展和区域地质对比,将特提斯中西段的古生代构造域划分为Iapetus-Tornquist洋加里东造山带、Rheic洋华力西期造山带、乌拉尔-天山中亚造山带和古特提斯Pontides-高加索-Mashhad造山带,并提出4个初步认识:(1) Rodinia超大陆在新元古代裂解形成的原特提斯大洋在欧洲以Iapetus和Tornquist缝合带为代表,它们在约420 Ma闭合形成加里东造山带,与我国秦祁昆造山系相似;(2) Rheic洋类似于特提斯东段的龙木错-双湖-昌宁-孟连洋,为古生代的特提斯主大洋,而泥盆纪形成的古特提斯洋实际上为主洋盆衍生的分支洋盆之一,Rheic洋的各分支洋盆在320~310 Ma闭合,形成华力西造山带和Pangea超大陆;(3)南阿尔卑斯Plankogel带、土耳其北部Pontides带和伊朗北部Rasht-Mashhad为古特提斯缝合带,代表泥盆纪—二叠纪的洋盆,晚石炭世—早三叠世丝绸之路岩浆弧与我国羌塘中部的望果山火山弧相对应;(4)特提斯中西段的基梅里造山带和羌塘中部的印支期造山带为古特提斯增生型造山带的典型代表。  相似文献   

7.
藏东北构造古地理特征及冈瓦纳北界的时空转换   总被引:8,自引:0,他引:8  
研究区位于南北向三江构造带与东西向羌塘构造带的衔接处,是特提斯构造域的重要组成部分。研究区包含金沙江、澜沧江、双湖-昌宁、班公湖-怒江4条古特提斯洋壳带及昌都-芒康、羌北、索县-左贡、多玛-安多4个微陆块的相关部位。4条缝合带时分时合,其间的微陆块则"藕断丝连"。前奥陶纪金沙江带属于泛冈瓦纳"泛非软基底"的北界,早古生代它还是"泛非"混合生物群与扬子区系的界线。泥盆纪—石炭纪,古特提斯形成南北2支,即金沙江带和双湖-昌宁带,与其间亲扬子的中间岛块群(昌都-芒康、羌北、索县-左贡)形成"多岛海"格局,此间,双湖-昌宁转换为冈瓦纳的北界,多玛-安多微陆块为亲冈瓦纳相。早、中二叠世,中间岛块(群)裂解为亲扬子的昌都-芒康和亲冈瓦纳的羌北、索县-左贡三岛块,形成多岛洋,冈瓦纳北界转换到澜沧江带。晚二叠世,古特提斯消亡,形成Pangaea联合古陆,研究区为陆间多岛海。晚三叠世印支运动阶段,金沙江、澜沧江和双湖-昌宁带相继转换为陆内造山带;与此同时,班公湖-怒江带与雅鲁藏布江带形成中特提斯北、南2支,其间为中间陆块群(基墨里),班公湖-怒江带是晚侏罗世—早白垩世消亡的,"基墨里"岛块群是晚白垩世增生在亚洲大陆之上的。喜马拉雅地块是喜马拉雅运动阶段才最后俯冲到亚洲大陆之下,转换为亚洲大陆。  相似文献   

8.
确定南澜沧江缝合带的火山岩地球化学证据   总被引:9,自引:0,他引:9  
本文着重根据火山岩的主量元素、稀土元素和微量元素特征厘定了我国西南“三江”地区昌宁-孟连带C1—P2火山岩和南澜沧江带P—T3火山岩的构造-岩浆类型。昌宁-孟连火山岩带为洋脊/准洋脊型-洋岛型玄武岩、蛇绿混杂岩带,代表澜沧江洋或古特提斯的残迹;南澜沧江火山岩带是一个陆缘火山弧带,是澜沧江洋盆向东俯冲消减、碰撞以及陆内俯冲过程的产物。两带火山岩是成对分布的古特提斯缝合带的产物。  相似文献   

9.
西南三江造山带地层区划   总被引:6,自引:5,他引:1  
西南三江为一复杂造山带,由特提斯大洋板块的怒江-孟连主大洋及欧亚大陆板块的扬子陆块大陆边缘弧盆系、冈瓦纳大陆板块北缘弧盆系构成。随着特提斯大洋怒江-孟连洋俯冲、消亡,后板块发生碰撞、走滑及岩浆岩侵位等,形成了现今由板块缝合带、增生杂岩带构成的西南三江造山带,造就了复杂的地层系统,包含史密斯地层、有限史密斯地层,非史密斯地层。本文突破"传统地层学"概念,按"构造地层学"的现代地层学概念建立了西南三江地层格架,划分出欧亚大陆板块的北羌塘-三江地层大区、特提斯大洋板块的班公湖-怒江-孟连构造-地层大区、冈瓦纳大陆板块的冈底斯-腾冲地层区。  相似文献   

10.
江达—维西陆缘火山弧的形成演化及成矿作用   总被引:16,自引:0,他引:16       下载免费PDF全文
江达-维西陆缘火山弧为金沙江弧后洋盆向西俯冲消减和斜向碰撞过程中形成,其过程经历了俯冲造弧-碰撞成弧-张裂成盆的复杂发展历史。早二叠世晚期-晚二叠世(P^21-P2)形成储冲型弧火山岩,早中三叠世(T1+2)形成碰撞型弧火山岩,晚三叠世早期(T^13)于裂谷盆地中发育“双峰式”火山岩。晚三叠世早期(T^13)裂谷分国地从北向南形成生达-车所-鲁麻弧后盆地、徐中-鲁春-红坡上叠(弧后)裂谷盆地和箐口  相似文献   

11.
西南三江造山带火山岩—构造组合及其意义   总被引:67,自引:0,他引:67  
岩石构造组合是指表示板块边界或特定的板块内部环境特征的岩石结合。中国西南“三江”造山带的火山岩可划分为五种火山岩-构造组合:洋脊型/准洋脊型组合,岛弧及陆缘弧组合,碰撞型组合,碰撞后组合及陆内拉张型组合。阐述了各种火山岩-构造组合的特点及构造含义。对在造山带火山岩岩石-构造组合分析中经常遇到的一些问题,如“构造岩片”研究方法、地球化学判别图解的使用条件、准洋脊型火山型组合的构造含义、蛇绿岩带-火山弧的成对性、岩浆作用的同步性和滞后性、以及火山岩的深部“探针”作用等问题进行了讨论。  相似文献   

12.
《China Geology》2021,4(4):630-643
The Nan Suture and Sukhothai Arc Terrane are products of the eastward subduction of the Paleotethyan Ocean during the Late Carboniferous to Triassic. However, their footprints in northwestern Laos are poorly constrained. New geochronological and geochemical data presented in this study demonstrate a Late Permian origin for the andesitic rocks in the B.Xiengnou area rather than Late Triassic. The breccia-bearing andesitic tuff in the B.On ultramafic complex yield a zircon U-Pb age of 260 ± 1.4 Ma, geochemically displaying a MORB-like signature. The andesitic tuff in the B.Kiophoulan-B.Houayhak belt gave the U-Pb age of 254 ± 1.3 Ma, with arc-like geochemical affinity. By combining geochronological and geochemical data from the Nan Suture and Sukhothai Arc Terrane, the authors suggest that the andesitic rocks in the B.On ultramafic complex formed in a back-arc basin background, which connected the Jinghong and Nan back-arc basin during the Permian; while the andesitic tuff in the B.Kiophoulan-B.Houayhak belt erupted in the Sukhothai continental arc setting.©2021 China Geology Editorial Office.  相似文献   

13.
Volcanism in Sanjiang Tethyan Orogenic Belt:New Facts and Concepts   总被引:1,自引:0,他引:1  
Sanjiang area in Southwestern China is tectonically sit-uated at the east end of Himalaya-Tethys tectonic do-main and at the conjunction of Tethyan MountainChain and Circum-Pacific Mountain Chain.It is one ofthe key areas to understand the global tectonics and alsoone of gigantic metallogenic provinces in China and evenin the world.Volcanism had occurred during the periodof time from Proterozoic to Cenozoic.The most impor-tant and active periods of volcanism,however,areCarboniferous,Permian and Triassic.The pattern ofspatial distribution of Sanjiang volcanic rocks andophiolites can essentially be described as that severalintra——continental micro-massif volcanic districts arerespectively sandwiched between each two of four couplingophiolite—are volcanic belts,which are successively fromwest to east:Dingqing-Nujiang belt,Laneangjiangbelt,Jinshajiang belt and Ganzi-Litang belt.Fourtectono-magmatic types of volcanic rocks have been recognized in Sanjiang area as follows:mid-ocean-ridge/para-mid-ocean-rid  相似文献   

14.
冈底斯造山带的时空结构及演化   总被引:143,自引:72,他引:143  
冈底斯带的构造属性及其构造单元划分一直是青藏高原基础地质研究中最热门的科学问题之一。根据新的地质调查资料、研究成果并结合我们的分析数据,对冈底斯带的地质构造格局进行了厘定和划分,讨论了冈底斯带晚古生代-中生代的构造演化历史。冈底斯带可划分为6类不同的构造单元和18个次级单元,这些不同级别的构造划分较为全面准确地概括了冈底斯带的地质面貌。通过对不同构造单元时空结构的剖析和对相关火山岩浆作用记录的分析,认为冈底斯带不是简单的地块、陆块或地体,而很可能是以隆格尔-念青唐古拉为主轴,经历石炭-二叠纪、早中三叠世、晚三叠世、早中侏罗世、晚侏罗世-早白垩世、晚白垩世-始新世六次造弧增生作用和相关的弧-陆、陆-陆碰撞作用并最终定型于新生代晚期的复合造山带,并在此基础上,提出冈底斯带的构造演化很可能受班公湖-怒江特提斯洋向南、雅鲁藏布洋向北的双向俯冲的制约。强调以增生弧为背景的火山岩浆弧(如昂龙岗日火山岩浆弧、东恰错弧、桑日火山弧)可能是冈底斯地区寻找斑岩铜矿的最佳有利场所。  相似文献   

15.
青藏高原东南缘“三江”复合造山成矿带南、北两段发育若干火成岩带,其间的时空关系并不清晰,原因在于位于构造带中段的兰坪盆地内火山岩缺乏年代学、地球化学制约。兰坪盆地西侧火山岩带由下至上由安山质晶屑凝灰岩、安山质集块-块状安山岩、玄武质熔岩组成,上部玄武质熔岩夹紫红色泥岩,并被紫红色泥岩覆盖。LA-ICP-MS锆石U-Pb测年结果表明,火山岩下部的晶屑凝灰岩形成时代为238Ma,中段安山岩喷发时间为233Ma,上段玄武质熔岩形成时代为229Ma。这套火山岩属于钙碱性-高钾钙碱性系列,具有高Al2O3和低MnO、P2O5和TiO2的特征,具有轻稀土元素富集的右倾型配分模式,无明显Eu异常。安山岩相对富集La、U等大离子亲石元素,Nb、Ta等高场强元素明显亏损,具有俯冲带弧火山岩典型特征,而玄武质熔岩具有富集型洋中脊玄武岩地球化学特征。结合其野外产状(覆于石炭纪陆缘碎屑岩之上)、地球化学特点及其随时间变化规律,认为这套岩石形成于陆缘弧环境,而晚期岩浆活动可能与俯冲板片断离、拆沉过程有关。兰坪盆地西缘火山岩与造山带内其他同时代火成岩一起组成一条近连续的大型岩浆岩带,带内绝大部分岩浆岩具有弧岩浆岩构造属性,部分显示板内岩浆岩地球化学特征。这条岩浆岩带可与具同等规模的龙木错-双湖(-澜沧江)-昌宁-孟连缝合带对应,推测其为该缝合带所代表的古特提斯主洋盆向由西(南)向东、北(东)方向俯冲过程的产物。  相似文献   

16.
In an attempt to constrain a Late Paleozoic tectono-metamorphic event along the Lancang River Zone, fourteen samples were processed for K/Ar dating on fine mineral fractions and detrital muscovites from this zone in southwestern Yunnan, China. The samples include mica schists, mylonites and gneisses from the Proterozoic Lancang Group and phyllites from the western part of the Simao Basin. In addition, one Ar/Ar analysis was performed on separated phengites from a blueschist of the central part of the Lancang Group. The results reveal a considerable spread of ages; the tectonic evolution of the zone is constrained by the new data, which accentuate two temporally separate, but spatially overlapping events: (i) a Late Carboniferous high-P/low-T metamorphism related to an east-vergent, Late Paleozoic thrust belt, inverting a Devonian to Carboniferous marginal basin of the Yangtze-Platform, and (ii) an upper Permian and Triassic low-P/high-T belt caused by a post-orogenic stage of rifting with distinct petrological and geochemical similarities of the igneous rocks to the Emeishan Large Igneous Province. These results imply that no active continental margin accounts for the subduction of the Paleotethys main branch, proposed to be recorded either along the Lancang River or the Changning-Menglian Belt.  相似文献   

17.
In an attempt to constrain a Late Paleozoic tectono-metamorphic event along the Lancang River Zone, fourteen samples were processed for K/Ar dating on fine mineral fractions and detrital muscovites from this zone in southwestern Yunnan, China. The samples include mica schists, mylonites and gneisses from the Proterozoic Lancang Group and phyllites from the western part of the Simao Basin. In addition, one Ar/Ar analysis was performed on separated phengites from a blueschist of the central part of the Lancang Group. The results reveal a considerable spread of ages; the tectonic evolution of the zone is constrained by the new data, which accentuate two temporally separate, but spatially overlapping events: (i) a Late Carboniferous high-P/low-T metamorphism related to an east-vergent, Late Paleozoic thrust belt, inverting a Devonian to Carboniferous marginal basin of the Yangtze-Platform, and (ii) an upper Permian and Triassic low-P/high-T belt caused by a post-orogenic stage of rifting with distinct petrological and geochemical similarities of the igneous rocks to the Emeishan Large Igneous Province. These results imply that no active continental margin accounts for the subduction of the Paleotethys main branch, proposed to be recorded either along the Lancang River or the Changning-Menglian Belt.  相似文献   

18.
The Xing’an–Mongolia orogenic belt is located in the southeastern segment of the Central Asian Orogenic Belt. Its tectonic evolution, especially during the Late Palaeozoic to Early Mesozoic, remains controversial. Here, we report new zircon U–Pb dates, whole-rock geochemistry, and Hf isotopes of representative samples from four plutons in the Linxi area of Northeast China to provide new constraints on this issue. Zircon U–Pb dating indicates that the intrusions were emplaced in two stages: (1) Late Permian to Early Triassic (the Banshifangzi and Xinangou plutons (252 ± 3)–(246.3 ± 3.3) Ma); and (2) Late Triassic (the Baoshan and Hada plutons (220.8 ± 2.7)–(211.4 ± 2.6) Ma). Their positive εHf(t) values (6.6–14.1), coupled with their geochemical characteristics, suggest that the provenance of investigated granitoids were most likely to be dominated by juvenile crustal materials. Based on these new data and previous studies, we propose three stages of tectonic evolution during the Late Palaeozoic–Early Mesozoic in the XMOB: (1) Late Carboniferous–Early Permian (330–270 Ma): double-sided subduction of the Palaeo-Asian Ocean; (2) Middle Permian–Middle Triassic (270–237 Ma): the closure of the Palaeo-Asian Ocean and subsequent continent–continent collision between the North China Craton and the South Mongolia Terrane; and (3) Late Triassic (237–211 Ma): post-collisional extension.  相似文献   

19.
The paleogeography of the Eastern Pontides was defined by the Paleotethys ocean to the north and a continental assemblage to the south, prior to Carboniferous time. The S-dipping subduction of Paleotethys beneath Gondwana caused the development of arc magmatism, mostly active in the Early Carboniferous. Cessation of magmatism during Late Carboniferous-Early Permian time was accompanied by the deposition of platform carbonates, which were rifted to open a back-arc oceanic basin (Karakaya ocean) during the Triassic.

Accompanying closure of this Triassic basin, the Ladinian-Late Triassic products of Neotethys, opening in the south, transgressively overlay the basement in the Keban continent to the south. However, transgression reached the northern region (Pontide continent) during Liassic time, because of a topographic high created by southward subduction of the Paleotethys ocean as well as closure of the Karakaya ocean.

During the late Cenomanian/Turonian to Eocene, an island arc evolved as a result of N-dipping subduction of Neotethys. The ophiolite-melange association was obducted onto the Pontide continent as a retrocharriage process in the Turonian-Maastrichtian, Paleocene, and the end of the early Eocene, and onto the Keban continent in Campanian-Maastrichtian and pre-late Lutetian time.

A continental-lacustrine environment developed, and partial melting of the thickened crust initiated the development of volcanic units in the Miocene. The region was affected by right-lateral strike-slip faulting (the North Anatolian fault) and a NE-SW-trending left-lateral strike-slip fault system (the Northeast Anatolian fault).  相似文献   

20.
本文在系统收集内蒙古林西-东乌旗地区晚古生代-早中生代岩浆岩的年代学、岩石地球化学以及锆石Hf同位素资料基础上,通过分析岩浆岩岩石组合随时空的变化规律,并结合区域地质资料,探讨了中亚造山带东南部洋盆演化和地壳增生等重要地质问题。研究结果表明,二连浩特-贺根山蛇绿岩带南、北两侧晚古生代-早中生代岩浆岩在年代学上显示不同的活动期次,具有不同岩石组合和地球化学特征,指示它们分属于不同的构造岩浆岩带。蛇绿岩带以北晚泥盆世-中二叠世岩浆活动在时间上呈连续分布的特征,并在晚石炭-早二叠世时期达到活动峰值。火成岩构造组合分析表明,晚泥盆世-石炭纪和早-中二叠世岩浆活动分别与二连浩特-贺根山洋盆向乌里雅斯太大陆边缘之下的俯冲和洋盆闭合后俯冲板片断离引起的软流圈上涌造成的区域伸展背景有关。蛇绿岩带以南岩浆活动时间上呈现石炭纪、早-中二叠世、晚二叠世-三叠纪幕式分布特征,各期岩浆活动前锋有随时间向南迁移的趋势。这三期岩浆活动分别与古亚洲洋板片向宝力道岛弧之下的俯冲、板片后撤以及洋盆消失之后古板块的碰撞造山作用有关。锆石Hf同位素分析表明,中亚造山带东南部晚古生代至早中生代时期存在显著的地壳增生;其中二连浩特-贺根山蛇绿岩带以北表现为地壳的垂向增生,以南表现为地壳的侧向增生。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号