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1.
古太平洋板块俯冲-增生时限：饶河增生杂岩的地球化学和年代学制约 总被引：1，自引：1，他引：0
饶河杂岩作为那丹哈达增生杂岩的主体,是古太平洋板块西向俯冲的直接证据。饶河增生杂岩组成与增生过程的研究对限定古太平洋板块向欧亚大陆的俯冲与增生过程具有重要的指示意义。本文在野外地质调查和饶河大岱地区大比例尺填图基础上,明确了饶河杂岩主要由枕状玄武岩、辉长岩以及大洋板块沉积地层(OPS)组成,这些岩石均呈构造透镜体状分布在海沟沉积物中,并被中生代花岗质岩脉所穿切,因此为限定饶河增生杂岩的组成、增生和就位时代提供了关键制约。地球化学数据表明玄武岩具有洋岛玄武岩(OIB)的地球化学属性。LA-ICPMS锆石测试结果表明该地区玄武岩和辉长岩的形成时代分别为166±2Ma和214±5Ma,限定了饶河杂岩中镁铁质-超镁铁质岩石的形成时代为晚三叠世至中侏罗世。结合该区粉砂质泥岩和砂岩的沉积时代下限分别为167±3Ma和133±4Ma,表明饶河杂岩的增生时代为167～133Ma,此外样品的碎屑年龄信息表明基质的物源为邻近的佳木斯地块和中亚造山带东段,其中前寒武的碎屑年龄在中国东北的多个陆块均有出现,可能源于早前存在的前寒武纪基底。本文测得侵入饶河杂岩的2个二长花岗岩形成年龄分别为126±1Ma和105±2Ma,表明饶河杂岩中的花岗岩脉主要形成于两个阶段,其中较老的花岗岩侵入体进一步限定了饶河杂岩的最终就位时代为133Ma至126Ma,表明古太平洋板块在中侏罗世至早白垩世存在西向俯冲-增生作用,为古太平洋板块的构造演化提供了重要的制约。 相似文献
2.
那丹哈达地体是中国境内唯一保存的古太平洋板块俯冲-增生的直接记录,包括跃进山杂岩和饶河增生杂岩。跃进山杂岩出露于那丹哈达地体的西缘,属于地体早期阶段的增生产物,对揭示古太平洋板块的俯冲-增生历史以及古亚洲洋构造域、泛大洋和古太平洋构造域之间的转换过程具有重要意义。本文通过野外地质调查明确了跃进山杂岩是一套构造混杂岩,主要由硅质岩、石英片岩、大理岩、二云母片岩、石英-云母片岩、变玄武岩、辉长岩、纯橄榄岩、异剥橄榄岩和单斜辉石岩组成。LA-MC-ICPMS锆石年代学测试结果表明变玄武岩原岩和辉长岩的形成时代分别为303±2Ma和278±2Ma,此外前人报道了跃进山杂岩中最年轻的玄武岩形成于232±5Ma,这些年代学研究成果限定了镁铁质-超镁铁质岩形成于303~232Ma。大量地球化学研究数据证实了跃进山杂岩中的玄武岩为洋中脊玄武岩(MORB)和洋岛玄武岩(OIB)。糜棱岩化绿泥石-绢云母板岩的绢云母^(40)Ar/^(39)Ar测试结果为193±1Ma,根据跃进山杂岩中最年轻的原岩时代为~220Ma,本文限定了跃进山杂岩的最终就位时代为220~193Ma。结合中国东北地区中生代增生杂岩及佳木斯地块和松辽地块东缘晚古生代至中生代的岩浆弧,本文揭示了中国东北地区古亚洲洋和泛大洋构造域向古太平洋构造域的转换发生在晚三叠世至早侏罗世。 相似文献
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《地学前缘》2017,(4):200-212
东亚陆缘中生代增生造山过程及变形响应一直以来都是中国区域地质研究的重大课题,也是东亚地质构造演化的一个难点和热点。其中一个最为关键的科学问题就是,古太平洋板块(Izanagi)何时开始启动俯冲?对中生代东亚大陆边缘产生何种影响?那丹哈达地体出露于中国东北,为一套构造混杂岩系,是中国境内由古太平洋板块俯冲-增生形成的唯一证据,为解决这一问题提供了可能。本文通过总结大量前人最新的岩石学、同位素年代学、沉积岩石组合、主干断裂、岩浆活动、古生物及古地磁等资料,试图厘定那丹哈达地体构造属性、增生过程、拼贴时间以及古太平洋板块开始俯冲的时间,并与周缘地体进行对比。结果表明:(1)那丹哈达增生杂岩分为饶河杂岩和跃进山杂岩,饶河杂岩具有洋岛玄武岩(OIB)的特征,不是前人认为的蛇绿岩,可称之为洋岛(海山)杂岩;跃进山杂岩具有洋中脊玄武岩(MORB)的特征,是典型的蛇绿岩,同时暗示古太平洋板块可能于晚三叠世开始启动俯冲,并在136~131 Ma期间就位于现今位置。(2)那丹哈达与日本丹波—美浓—尾足地体都是侏罗纪增生楔,在沉积岩石组合和年龄、放射虫类型及分布、地质构造等特征上都非常相似,在中新世日本海打开之前应是一个统一的超级地体。 相似文献
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跃进山杂岩中二叠纪变玄武岩的锆石U-Pb年代学、地球化学及其地质意义 总被引：4，自引：0，他引：4
那丹哈达增生杂岩为中国东部古太平洋板块俯冲最为可靠的地质记录之一,对限定古大洋板块的西向俯冲具有重要意义。跃进山杂岩位于那丹哈达增生杂岩的增生前锋位置,发育典型的增生杂岩组合。其中变玄武岩类多呈构造透镜体状与硅质岩、片理化泥岩和片岩相伴产出,部分可见变余枕状构造。本文对位于研究区北部勤得利和南部东方红地区的3件变玄武岩样品进行了同位素年代学和地球化学研究。变玄武岩样品中含有数量不等的锆石,多呈自形-半自形,条带结构,结合其较高Th/U比值(0.15~2.4),暗示其具有典型的基性岩岩浆锆石特征。锆石LA-ICP-MS U-Pb年代学证据显示跃进山杂岩中的变玄武岩形成于270±2 Ma~279±4 Ma,表明其原岩形成时代应为早二叠世。地球化学分析显示,跃进山杂岩南、北地区的地球化学组成略有不同,北部勤得利地区的变玄武岩具有富Na2O,贫Mg O,轻度富集轻稀土元素,富集大离子亲石元素Sr和Ba,亏损高场强元素Nb等特征,南部东方红地区变玄武岩具有贫Na2O、K2O和Mg O,亏损轻稀土元素和富集大离子亲石元素Rb、Sr等特征,结合构造判别图解,北部勤得利地区变玄武岩形成于消减带或俯冲带(SSZ)构造背景下,而南部东方红地区变玄武岩显示为N-MORB型,形成于大洋中脊(MOR)环境。结合前人资料及北部勤得利地区岩石的年代学与地球化学研究确定了佳木斯地块与那丹哈达地体之间的缝合线的具体位置为勤得利-二龙山-尖山子乡—线,并对该岩浆岩演化的动力学背景进行了初步分析。 相似文献
5.
东北中生代增生杂岩及对古太平洋向欧亚大陆俯冲历史的制约 总被引：8，自引：7，他引：1
吉林-黑龙江东部地区的中生代增生杂岩,主要由吉林-黑龙江高压变质带和那丹哈达增生杂岩(或那丹哈达地体)组成。它们将为古亚洲洋与环太平洋构造域的转换作用,大洋板块地层(OPS)层序重建,特别是古太平洋板块向欧亚大陆的俯冲历史提供重要的科学依据。吉林-黑龙江高压带分布在佳木斯-兴凯与松辽地块之间的具有高压变质带性质的缝合带,新的地质年代学研究表明其形成时代为210～180Ma,表明晚三叠-早侏罗世为南北向古亚洲洋关闭和西向俯冲增生开始的关键时期。那丹哈达增生杂岩则发育在佳木斯-兴凯地块东侧,并具体分为西部的跃进山杂岩和东部的饶河杂岩。新近发表的数据显示,跃进山杂岩就位时代为210～180Ma,这与佳木斯-兴凯地块西缘的吉黑高压带形成时代相似。而饶河杂岩就位时代为晚侏罗-早白垩世,最晚期就位的时代为早白垩世(137～130Ma)。因此,吉黑东部地区的中生代增生杂岩为古太平洋向欧亚大陆中生代的俯冲过程提供了关键的信息。 相似文献
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那丹哈达地体中的跃进山和饶河增生杂岩对于重建古太平洋板块的俯冲—增生过程以及揭示古太平洋和古亚洲洋之间的构造体制转换过程提供了重要地质证据。然而古太平洋板块俯冲至欧亚大陆下的起始时间以及跃进山增生杂岩相关的古洋盆属性存在较大争议。本文对跃进山增生杂岩的野外地质调查显示其具有“基质+岩块”的物质组成特征,对其中的基质变泥质粉砂岩碎屑锆石U- Pb定年结果显示其沉积时代不早于233. 1 ± 5. 1 Ma,绿片岩岩块的锆石U- Pb定年结果显示其原岩的结晶年龄为194. 7 ± 4. 8 Ma,并具有洋岛玄武岩的地球化学属性。结合前人新近发表的跃进山地区和区域上增生杂岩的岩块和基质的年代学资料,表明跃进山增生杂岩的增生时代主体为三叠纪,而最终就位时代为早侏罗世早期,它为古太平洋板块俯冲—增生的物质记录。 相似文献
7.
江南造山带西南段梵净山地区镁铁质-超镁铁质岩:形成时代、地球化学特征与构造环境 总被引：1，自引：0，他引：1
梵净山地区位于江南造山带的西南缘,这里新元古代的镁铁质-超镁铁质岩浆岩广泛发育,岩性包括枕状熔岩、超镁铁质-镁铁质岩床群以及浅成侵入的辉长岩,成分属拉斑玄武岩系列。其中枕状熔岩以富集轻稀土元素和Rb、Ba、Th、U等强不相容元素,亏损高场强元素Nb和Ta,低的εNd(t)值为特征,明显不同于洋脊玄武岩,推测其成因可能与富集型地幔的部分熔融有关,形成于与俯冲有关的弧后小洋盆环境。超镁铁质-镁铁质岩床群主要由辉绿岩和碳酸辉橄岩组成,其中超镁铁质岩床群中出现大量的原生碳酸盐矿物,指示它们形成于拉张(甚至裂谷)的构造环境。辉长岩可能是区内最晚形成的岩浆岩,其SHRIMP锆石U-Pb年龄为821±4Ma。由枕状熔岩经超镁铁质-镁铁质岩床群到辉长岩,高场强元素Nb和Ta的亏损程度减弱、轻稀土元素的富集程度降低、εNd(t)值由负值变为正值,指示随时间的由早到晚,来自亏损地幔的物质不断增加。推测梵净山地区新元古代岩浆作用的顺序大致为:枕状熔岩(～840Ma)→白云母花岗岩(～838Ma)→碳酸超镁铁质岩床群→镁铁质岩床群→辉长岩(～821Ma),构造环境由俯冲-碰撞到拉张-裂谷。 相似文献
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9.
黑龙江饶河枕状玄武岩地质、地球化学特征及其构造属性 总被引：1，自引：0，他引：1
为了确定饶河玄武岩的构造属性,在野外地质观察的基础上,对玄武岩进行岩石学研究和地球化学分析。玄武岩具有典型的枕状构造、淬冷边、中空骸晶和鬣刺结构等特征,反映其形成于海底喷发环境。化学分析样品具有高TiO_2、MgO和低Al_2O_3、CaO、P_2O_5、K_2O等特征,富集大离子亲石元素(Rb、Sr和Ba),微量元素蛛网图呈向上隆起形态,稀土元素配分曲线为右倾型(∑LREE/∑HREE为5.8~6.5),无δEu异常(0.92~0.97),表明样品具有洋岛玄武岩特征。主量和微量元素构造环境判别图指示了样品形成于洋岛或板内环境。样品与亚速尔型和夏威夷型洋岛玄武岩地球化学特征对比,表现出明显的夏威夷型洋岛玄武岩特征。岩石源区分析揭示出岩浆具有地幔热柱起源,并有先期交代地幔熔体的混入,岩浆源区还受壳幔循环的影响。研究表明,饶河枕状玄武岩为夏威夷型洋岛玄武岩,形成于洋壳消减阶段的洋中脊轴外板内喷发环境,为饶河地区存在成熟的洋盆提供直接证据。结合区域研究成果,认为饶河地区经历了古太平洋板块的扩张、洋中脊轴外板内地幔柱上涌、洋壳俯冲消减以及向佳木斯地块仰冲增生的构造演化过程。 相似文献
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鄂北随州大洪山地区出露大量镁铁质岩(如:辉长岩、辉绿岩、(枕状)玄武岩),它们主要以岩块的形式构造混杂在一套碎屑岩中,表现为典型造山带基质-岩块混杂的特征。大洪山镁铁质岩为拉斑玄武岩系列岩石组合,地球化学方面,不相容元素Rb、Ba、K、Th、U富集,高场强元素Nb、Ta亏损,表现为岛弧玄武岩的特点,而平坦的稀土配分模式(ΣLREE/ΣHREE=1.41～4.48,LaN/YbN=0.76～4.79),Zr/Y=2.65～5.38,Ti/V=29.19～54.97,又可与洋中脊玄武岩对比。因此,我们推测大洪山镁铁质岩属于MORB-like玄武岩(或前弧玄武岩)类岩石组合,其形成于洋内初始俯冲环境,成岩岩浆由俯冲洋板片脱水交代亏损洋中脊地幔减压熔融产生。通过LA-ICP-MS锆石U-Pb测年,分别获得南风垭、绿林寨玄武岩(816.6±7.6) Ma (MSWD=0.47)、(813.1±4.8) Ma (MSWD=0.37)的成岩年龄,结合已经取得的杨家棚辉长岩947 Ma、厂河枕状玄武岩824 Ma、绿林辉绿岩820 Ma的年龄结果,说明大洪山地区的这套前弧镁铁质岩组合大致形成于817～947 Ma,它们可能是多阶段洋内俯冲的产物。大洪山地区这套前弧镁铁质岩的厘定说明扬子地块与桐柏-大别地块之间晋宁期发生过一定规模的洋内-洋陆俯冲和造山运动,二者可能曾在青白口纪晚期拼合到一起。 相似文献
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The eastern segment of Central Asian Orogenic Belt underwent not only a long evolution history related to the Paleo-Asian Ocean during Paleozoic but also the tectonic overprinting by the westward subduction of Paleo-Pacific Ocean crust during Mesozoic. When the subduction of Paleo-Pacific Ocean crust started has been long debated issue for understanding the tectonic evolution of the eastern Asian continental margin. The eastern margin of the Jimusi Block (Wandashan Terrane) preserved complete records for the accretionary process of the westward subduction of Paleo-Pacific Ocean crust. Comprising the Yuejinshan Complex and Raohe Accretionary Complex (RAC), the Wandashan Terrane is located in the eastern margin of Jiamusi Block, NE China, and is considered to be an accretionary wedge of the westward subducting oceanic crust. To reconstruct the marginal accretion processes of the Jiamusi Block, the structural deformation of the Wandashan Terrane was investigated in the field and the geochronology of the Dalingqiao and Yongfuqiao formations were studied, which were formed syn-and-post RAC accretion respectively. The Yuejinshan and Raohe complexes were discontinuously accreted to the eastern margin of the Jiamusi Block. Contrary to the previous consideration of the Late Triassic to Early Jurassic, this study suggests that the Yuejianshan Complex in southwest Wandashan Terrane probably accreted from Late Carboniferous to Middle Permian, which was driven by unknown oceanic crust subduction existing to the east (present position) of the Jiamusi Block at that time. The siltstones of the Dalingqiao Fm. yield the youngest zircon U-Pb age of 142 ± 2 Ma, indicating the emplacement of the RAC not earlier than the Late Jurassic. Thus, the RAC might start to accrete from the Jurassic and emplace during 142–131 Ma, resulted from the Paleo-Pacific subduction which started from the Late Triassic to Early Jurassic. 相似文献
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The Wandashan accretionary complex(AC),consisting of the Raohe and Yuejinshan complexes,is located on the continental margin of Northeast Asia and represents an excellent source of information about Paleo-Pacific subduction and accretion.However,the protolith nature and tectonic evolution of the Wandashan AC are under debate.This contribution reports new geochronological,geochemical,and Sr-Nd-Pb-Hf isotopic data for ophiolitic rocks from the Wandashan AC.The 169-166 Ma plagioclasites and homogeneous gabbros from the Raohe complex are OIBs while 228-214 Ma homogeneous gabbros are continental VABs.Cumulate gabbros from the Yuejinshan complex formed at 280-278 Ma and～220 Ma and have similar characteristics with E-MORB and N-MORB,respectively.They are BABBs and their primary magma was derived from a source region between EMI and EMII that was affected by con-tinental crustal contamination as well as subduction-zone metasomatism.Combined with previous stud-ies,we suggest that the onset of subduction of the Paleo-Pacific Plate was in the Early Permian.Subsequently,a back-arc basin,whose present suture is on the eastern margin of the Jiamusi Massif,formed and widened during 280-232 Ma,after which the basin closed and BABBs were emplaced to form the Yuejinshan complex during 210-180 Ma.The formation of VABs of the Raohe complex is coincident with the closure of the back-arc basin,and together with the 169-166 Ma OIBs,they constitute a major part of the Raohe complex.The accretionary process was completed during 133-131 Ma.Taken together,the ophiolitic rocks indicating multistage magmatism in the Paleo-Wandashan region recorded the formation-closure process of back-arc basin and the accretionary process of the Wandashan AC,during the westward subduction of the Paleo-Pacific plate.The back-arc basin identified in our study sheds new lights on geodynamic evolution model of subduction and accretion of the Paleo-Pacific Plate on the continental margin of NE Asia. 相似文献
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佳木斯地块位于中亚造山带东段,是我国东北地区一个重要的大地构造单元,古生代以来经历了复杂的多构造体系叠合的演化过程。本文在总结近二十年已报导的相关研究成果基础上,结合笔者近年工作,探讨了佳木斯地块的基底属性和来源,重塑了佳木斯地块西缘碰撞拼贴,以及东缘俯冲-增生的构造演化过程。研究表明,佳木斯地块具有亲冈瓦纳大陆的构造属性,裂离后经历了长距离的北漂。与松辽地块先后两次拼合,首次发生于中志留世(～425Ma),在晚二叠世前后(～250Ma)沿原缝合带位置发生裂解,拉张出新的有限洋盆(牡丹江洋),并于侏罗纪(185～145Ma)与松辽地块沿牡丹江-依兰构造带再次碰撞拼贴,形成了高压变质的黑龙江增生杂岩带。而佳木斯地块东缘受晚石炭世-晚三叠世(305～250Ma)泛大洋的俯冲-增生事件影响,形成了跃进山增生杂岩,随后于中侏罗世-早白垩世(165～128Ma)在古太平洋板块的西向俯冲作用下,形成了饶河增生杂岩。因此,佳木斯地块的构造演化既涉及了晚古生代古亚洲洋构造域的消亡,又经历了中生代古太平洋构造域的叠加与改造,而黑龙江杂岩的形成标志着古太平洋构造体制与古亚洲洋构造体制的转换始于晚三叠世(～210Ma)。 相似文献
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Tectonic implications of the Nan Suture Zone and its relationship to the Sukhothai Fold Belt, Northern Thailand 总被引：2，自引：0，他引：2
The Nan Suture and the Sukhothai Fold Belt reflect the processes associated with the collision between the Shan-Thai and Indochina Terranes in southeast Asia. The Shan-Thai Terrane rifted from Gondwana in the Early Permian. As it drifted north a subduction complex developed along its northern margin. The Nan serpentinitic melange is a thrust slice within the Pha Som Metamorphic Complex and in total this unit is a Late Permian accretionary complex containing offscraped blocks from subducted oceanic crust of Carboniferous and Permian age. The deformational style within the Pha Som Metamorphic Complex supports a west-dipping subduction zone. The Late Permian to Late Triassic fore-arc basin sediments are preserved in the Sukhothai Fold Belt and include a near continuous sedimentary record, at least locally. The whole sequence was folded and complexly thrust in the Late Triassic as a result of the collision. Late syn- to post-kinematic granites place an upper limit of 200 Ma on the time of collision. Post-orogenic sediments prograded across the suture in the Jurassic. 相似文献
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重点分析和总结了由显生宙增生复合体和造山带混杂岩重建的年轻造山带洋板块地层--太平洋洋板块地层,也简要介绍了东古印度洋(东新特提斯洋)和古亚洲洋洋板块地层的重建情况。通过对阿拉斯加南部中生代增生地体、俄罗斯远东和中国东北侏罗纪-早白垩世增生复合体、日本二叠纪-侏罗纪-白垩纪等不同时期的增生复合体、菲律宾侏罗纪增生复合体和美国加州海岸山脉中侏罗世-古新世弗朗西斯卡杂岩体等不同单元的岩石学特征、古生物地层学、年代地层学、因逆冲导致的构造叠置和混杂失序特征及演化阶段的分析,重建了太平洋洋板块地层。其中加州海岸山脉中侏罗世-古新世弗朗西斯卡杂岩体的研究比较深入,对该区俯冲带上叠蛇绿岩(大峡谷群弧前盆地蛇绿岩)和弗朗西斯卡北部马林海岬杂岩体(原岩为洋中脊玄武岩)进行了有效区分,不仅还原了太平洋板块的俯冲碰撞过程,还厘清了与之伴生的弧前盆地裂陷和扩张过程。另外,板块俯冲的滞留和幕式增生在活动时间较短的板块俯冲体系中可能不容易识别。 相似文献
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Liu K.Zhang J.-J.Ge M.-H.Ling Y.-Y. 《矿物岩石地球化学通报》2016,(6):1098-1108
The eastern pari of the Xing-Meng Orogenic Belt( XMOB )consists of the Lesser Xing'an-Zhangguangcai Range Orogenic belt, the Bureya-Jiamusi-khanka Block and the Sikhote-Alin accretionary belt. This area is located between the Paleo-Asian oceanic and Paleo-Pacific tectonic regimes. Recent researches imply that the Paleo-Pacific subduction might have begun since early Permian and influenced the both sides of the Mudanjiang Fault during Triassic, which generated a N-S trending magmatic belt and accretionary complexes, such as the Heilongjiang Complex. In Late Jurassic to Early Cretaceous, some tectono st rati graph ic terranes were produced in Sikhote-Alin, which were then dismembered and migrated northwards in late Early Cretaceous by sinistral strike-slip faults. The continental margin parallel transportion weakened subduction-related magmatism in NE China which was under an extensional setting. However, in Lite Cretaceous, the Paleo-Pacific subduction was re-Activated in the eastern XMOB, which contributed to the magmatism in Sikhote-Alin. 相似文献