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

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。     

安徽大别山石英质玉矿矿床地质特征及开发利用前景分析 ——以霍山县白莲岩地区石英质玉矿为例

大别山地区石英质玉简称"大别山玉",主要分布于北大别变质杂岩带核部.地层为古元古代—新太古代大别岩群,新元古代中酸性侵入岩、燕山期花岗岩分布广泛,断裂构造极为发育.霍山县白莲岩地区石英质玉矿矿体呈脉状、透镜状伴随硅化构造破碎带产出,玉石颜色丰富,质地细腻,具有一定的经济价值和开发利用前景.     

华南在Rodinia古陆中位置的讨论——扬子地块西缘变质-岩浆杂岩证据及其与Seychelles地块的对比

沿扬子地块西缘出露的一系列变质杂岩的构造性质及形成时代是分析华南地块大地构造属性的关键。这些杂岩均被初始为低角度的正断层所围限 ,具有变质核杂岩的构造性质 ,其剥露时间在177Ma左右。目前 ,对这一区域几个代表性杂岩体进行的系统的岩石学和地球化学分析表明 ,这是一套主体为与俯冲板块有关的岛弧型岩浆杂岩 ,其形成时代从 72 6～ 86 4Ma ,时间跨度在 10 0Ma以上。证明这些岩石的形成与地幔柱作用无关。上述结果与最近在Madagascar东北缘、Seychelles岛及印度的Malani的一条类似的变质岩浆杂岩带的地球化学与地质年代学研究结果完全吻合 ,这个构造带被解释为一条沿Mozambique洋东缘的巨大的向东俯冲的安第斯型俯冲 岩浆岛弧带。据此我们推测在Rodinia古大陆中 ,华南地块位于印度板块东北缘 ,其南东则可能与澳大利亚相接。     

西太平洋俯冲带的演变: 来自东北亚陆缘增生杂岩的制约

本文系统总结了东北亚陆缘晚古生代和中生代增生杂岩的构成与形成时代,并结合同时代火成岩组合及其时空变异以及沉积建造组合,重塑了西太平洋板块俯冲带的演变历史。结果表明: ① 位于佳木斯地块东缘的跃进山杂岩代表了二叠纪俯冲带,它是古亚洲洋构造体制的产物;② 侏罗纪增生杂岩代表了侏罗纪俯冲带,与陆缘同期钙碱性火成岩组合以及含煤建造一起,共同揭示了古太平洋板块西向俯冲的开始;③ 侏罗纪增生杂岩中—晚侏罗世和早白垩世早期陆源碎屑岩物源的变化,与古地磁和生物学证据一起,共同揭示了古太平洋板块小角度斜向俯冲和东北亚陆缘走滑的构造属性,导致了低纬度侏罗纪增生杂岩向高纬度的推移;④ 白垩纪—古近纪增生杂岩与陆缘白垩纪—古近纪岩浆作用一起代表了该期俯冲带的存在,自早白垩世到晚白垩世再到古近纪岩浆作用范围向海沟方向的收缩,揭示了古太平洋板块西向俯冲以及俯冲板片后撤（rollback）过程的发生,同时标志着东亚大地幔楔的形成;⑤古近纪晚期—新近纪早期日本海的打开,标志着现今太平洋板块俯冲带以及东北亚大地幔楔的形成。     

宿松杂岩中白云母的矿物学特征及地质意义

大别山为印支期扬子陆块和华北陆块之间的碰撞造山带。太湖—宿松地区位于大别山东段部位,主要由扬子陆块北缘不同变质程度的变质基底和少量浅变质盖层组成。本文选择了宿松杂岩中的白云母进行探针分析以及X射线粉末衍射分析,研究结果表明宿松杂岩中的白云母都是2M₁型且均为多硅白云母。其中,多硅白云母的晶胞参数b₀平均值为9.039,显示宿松杂岩的变质压力为中压—高压。根据宿松杂岩中白云母的显微变形特征可以知道白云母至少存在着两期变形,一期是导致石榴子石压力影形成和白云母右旋的构造作用,应该对应着燕山期大别造山带中-下地壳物质发生平行造山带向东流动的地质事件。另一期是导致白云母形成涡流构造形成的构造作用,这一期构造应该对应扬子板块和华北板块碰撞事件。根据白云母中的Ti温度计和多硅白云母压力计可以得出宿松杂岩的变质条件为T=480 ℃～579 ℃,P=0.7～1.2 GPa,属于绿片岩相到角闪岩相。     

大兴安岭地区古生代构造格架重建:来自俯冲增生杂岩研究进展

大兴安岭地区古生代处于古亚洲洋闭合阶段,其间发育众多的弧盆系和蛇绿岩带,笔者等在大兴安岭地区1: 1 000 000地质编图和野外地质调研基础上,应用“洋板块地质”学术思想在大兴安岭地区元古宙、古生代地质体中划分出一系列“俯冲增生杂岩”、地块基底残块、岛弧、弧前盆地、弧后盆地等构造单元,结合陆(地)块和岩浆弧、弧前盆地、弧后盆地和“俯冲增生杂岩”的时空展布,划分出9条俯冲增生杂岩带,其中新识别出3条俯冲增生杂岩带。俯冲增生杂岩带主要分布于兴蒙造山带内部各地块之间和地块与大型岛弧带之间,相当于地块间及地块与岛弧带间的缝合带。依据俯冲增生杂岩带两侧对应的陆(地)块、岛弧带等构造级别,归并出5条结合带。俯冲增生杂岩带的展布方向以北东向为主,时代自北向南依次变新,从早奥陶世演化到中—晚二叠世,暗示古亚洲洋洋盆向大兴安岭地区陆(地)块俯冲作用最早发生在北部额尔古纳一带,逐渐向南后撤,不断形成新的洋壳和产生俯冲增生作用,相应的活动陆缘从北部额尔古纳地块向南逐渐增生,配套弧盆系时代也逐渐向南变新。早—中三叠世至西拉木伦一带发生陆-陆拼贴,完成华北板块与西伯利亚板块的对接。通过对大兴安岭地区古生代“俯冲增生杂岩”的研究,重建了大兴安岭地区古生代构造格架,提高了古亚洲洋东段洋-陆转换的研究程度。     

益阳火山岩特征及其形成构造环境分析

益阳火山岩中的熔岩、辉长辉绿岩和玄武质科马提岩,分别与蛇绿岩套中的熔岩、熔岩中的脉岩或岩墙杂岩和层状堆晶辉长岩有相似或相同的化学成分与微量元素含量,它们具有蛇绿岩套属性。与邻区广西、江西和安徽等省的蛇绿岩套分布在同一带上。因而认为,湖南境内沿通道—淑浦—宁乡—浏阳一带存在一条元古宙的古板块消减带,它控制了湖南中北部地区大地构造的演化和发展。     

辽北法库韧性剪切带变形及其区域构造意义

晚古生代—早中生代古亚洲洋板块俯冲华北板块在辽北法库地区形成大型产状近水平的韧性剪切带。剪切带发展伴随着多期幔源及壳源的岩浆侵入,侵入岩在韧性剪切作用下发生韧性变形,记录了韧性剪切带变形历史。详细的野外地质调查结合岩石的宏观变形、显微构造及石英c轴组构特征分析,揭示了法库韧性剪切带内五龙山杂岩、高丽沟杂岩、早期十间房超单元变形处于上盘向北的剪切作用之下,晚期十间房超单元岩石变形指示构造运动转变为上盘向南剪切。LA-ICP-MS锆石U-Pb分析结果显示高丽沟杂岩变形时间为264.7±3.6 Ma(MSWD=1.3),早期十间房超单变形时间为253.9±4.3 Ma(MSWD=3.3),晚期十间房超单元244.0±3.0 Ma(MSWD=1.9)。岩石地球化学特征表明早期十间房超单元及小房申岩体中部分岩石来源于部分熔融的岩石圈地幔。结合前人研究成果,我们认为华北板块北缘东段(辽北地区)晚二叠世(264.7~253.9 Ma)处于古亚洲洋板块俯冲华北板块作用之下;晚二叠世至早三叠世(253.9~244.0 Ma)构造体制转变为碰撞后伸展且逐渐停止,244.0±3.0 Ma碰撞后伸展逐渐结束;构造体制转变并逐渐结束的过程是壳幔共同作用的结果,暗示了古亚洲洋板块的俯冲板片断离、重力失衡,这标志着辽北地区古亚洲洋构造域演化结束。     

洋板块地质研究进展

中国存在多个时代、多种类型的造山带,发育了多种多样的俯冲增生杂岩带,经历了复杂多变的洋陆转换过程,如何揭示包括洋内演化和洋陆转换等的造山过程一直是一个难题。为此,中国区域地质志项目组提出了洋板块地质研究,试图通过对造山系俯冲增生杂岩带、蛇绿岩带等洋岩石圈地质建造、结构构造进行系统研究,再造洋岩石圈从洋中脊形成到海沟俯冲消亡、转换成陆的地质作用全过程。本文介绍了洋板块地质提出到现今主要的研究进展,包括四个方面。一是,初步建立了洋板块地质格架,洋板块地质的研究包括俯冲增生杂岩的物质组成、蛇绿岩类型及其形成的构造环境、洋板块沉积组合和洋板块地层、岛弧火成岩组合、洋陆转换的过程和机制、洋-陆转换过程与成矿作用等重要内容。二是,识别出北山牛圈子—马鬃山、嘉荫—依兰、陈蔡、东昆仑布青山—阿尼玛卿、鹰扬关、大洪山、甘孜—理塘、新余神山—新干神政桥等中国陆域62条主要的俯冲增生杂岩带/增生杂岩带。俯冲增生杂岩带是认识、理解造山系时空结构、组成和演化的关键。三是,在祁连地区识别出较为完整的洋内弧岩石组合。洋盆演化形成大陆过程中的洋内俯冲带是大陆的诞生地,洋内俯冲作用形成的洋内弧是洋盆演化形成大陆的初始弧。洋内弧火成岩组合序列的发现为研究洋陆转换过程提供了岩石学依据。祁连造山带是洋板块地质研究的经典地区之一。研究显示,当金山出露完整的洋内弧岩石组合,这些岩石记录了洋内弧从初始俯冲到发育成熟的全过程,为探讨祁连造山带原特提斯洋构造演化提供了新的依据。四是,制定了洋板块地质构造图编图方案,编图内容主要包括俯冲增生杂岩带、岩浆弧、高压-超高压带、俯冲期和碰撞期构造形变要素和构造演化等。编图单元分为三级:一级为俯冲增生杂岩带;二级为岩片;三级包括基质和岩块。编图过程中需要明确岩浆弧的性质和归属,明确图面上某一岩浆弧与哪个蛇绿混杂岩或大洋配套。图面上对于构造要素的表达重点是区分俯冲和碰撞阶段。通过构造变形的时态、相态、位态研究,识别俯冲期和碰撞期的构造变形形迹。这是洋板块地质初步的研究成果,以俯冲增生杂岩带的研究为基础,探讨特提斯洋等大洋的演化、中国东部古太平洋/太平洋转换与中新生代成矿关系等重大基础地质问题是洋板块地质研究下一步的工作方向。目前,洋板块地质的研究还处于试点阶段,洋板块地质与成矿的成因联系等重大地质问题尚需今后更深入地研究。     

北大别超高压榴辉岩中麻粒岩相变质的多期记录

<正>大别山是三叠纪华南板块向华北板块之下俯冲形成的碰撞型造山带,包含南大别低温榴辉岩带、中大别超高压变质带和北大别杂岩带等3个含榴辉岩的岩石单位,简称南大别、中大别和北大别。北大别超高压榴辉岩普遍经历过多阶段变质演化过程,特别是峰期之后的麻粒岩相变质叠加,表现为早期的绿辉石退变为细粒的单斜辉石+斜长石+斜方辉石后成合晶(Xu S-T et al.,2000;Liu Y-C et al.,2005,2007,2011,     

大别地区的变质作用及与碰撞造山过程的关系

大别造山带从南到北可分为５个变质构造单元：扬子北缘蓝片岩带、突松变质杂岩带、南大虽碰撞杂岩带、北大别变质杂岩带和北淮阳变质带。各个变质构造单元中不同岩石的变质作用可划分为３种类型：（１）超高压型。以含柯石英（及金刚石）的榴辉岩为代表,仅见于南大别碰撞杂岩带中,这类岩石的ＰＴ轨迹反映洋壳Ｂ型俯冲的特点。（２）高压型。见于大别山南部的蓝片岩带、宿松变质杂岩带和南大别杂岩中的变质沉积岩及部分片麻岩中,与     

Plate kinematics, origin and tectonic emplacement of supra-subduction ophiolites in SE Asia

A unique feature of the Circum Pacific orogenic belts is the occurrence of ophiolitic bodies of various sizes, most of which display petrological and geochemical characteristics typical of supra-subduction zone oceanic crust. In SE Asia, a majority of the ophiolites appear to have originated at convergent margins, and specifically in backarc or island arc settings, which evolved either along the edge of the Sunda (Eurasia) and Australian cratons, or within the Philippine Sea Plate. These ophiolites were later accreted to continental margins during the Tertiary. Because of fast relative plate velocities, tectonic regimes at the active margins of these three plates also changed rapidly. Strain partitioning associated with oblique convergence caused arc-trench systems to move further away from the locus of their accretion. We distinguish “relatively autochthonous ophiolites” resulting from the shortening of marginal basins such as the present-day South China Sea or the Coral Sea, and “highly displaced ophiolites” developed in oblique convergent margins, where they were dismantled, transported and locally severely sheared during final docking. In peri-cratonic mobile belts (i.e. the Philippine Mobile Belt) we find a series of oceanic basins which have been slightly deformed and uplifted. Varying lithologies and geochemical compositions of tectonic units in these basins, as well as their age discrepancies, suggest important displacements along major wrench faults.We have used plate tectonic reconstructions to restore the former backarc basins and island arcs characterized by known petro-geochemical data to their original location and their former tectonic settings. Some of the ophiolites occurring in front of the Sunda plate represent supra-subduction zone basins formed along the Australian Craton margin during the Mesozoic. The Philippine Sea Basin, the Huatung basin south of Taiwan, and composite ophiolitic basements of the Philippines and Halmahera may represent remnants of such marginal basins. The portion of the Philippine Sea Plate carrying the Taiwan–Philippine arc and its composite ophiolitic/continental crustal basement might have actually originated in a different setting, closer to that of the Papua New Guinea Ophiolite, and then have been displaced rapidly as a result of shearing associated with fast oblique convergence.     

On the origin of ophiolite complexes in the southern Tethys region

Regional geological evidence appears to be incompatible with the hypothesis that the alpine-type ophiolites, which are found at numerous localities on the northern margins of the Arabian and Indian continental blocks, represent oceanic lithosphere emplaced by obduction. All of them were emplaced during the same brief period in the Late Cretaceous, at which time these Gondwana continents were at varying distances from Eurasia and were drifting passively northwards towards a north-dipping subduction zone at the opposing, northern side of the closing Tethys ocean: they were apparently emplaced on inactive continental margins which show no evidence of underlying subduction or, necessarily, of compression. As a possible solution to the problem of their origin, it is suggested that they reached their present positions above the miogeosynclines on the continental margins by means of gravitational gliding from an uplift, caused by the intrusion/extrusion of mantle material at a locus of weakness along those margins. Although some material from the former Tethys floor may be included, the ophiolites are thought to consist primarily of mantle material that has broken through the earth's surface under conditions of tension. The necessary identification of ophiolites as fragments of oceanic lithosphere, as marking former plate boundaries, and as indicative of a compressive environment, should be regarded with caution.     

桐柏—大别山高压超高压变质带

桐柏—大别山高压超高压变质带自南向北可划分为３个带：绿帘－蓝片岩相变质带，高压榴辉岩相变质和超高压榴辉岩相变质带，超高压变质带形成于加里东期洋壳俯冲作用过程中，而前两个高压变质带则是印支期陆－陆俯冲－碰撞作用的产物。     

早前寒武纪洋壳的地质记录及其板块构造意义

元古宙蛇绿岩的不断发现表明威尔逊旋回至少在早元古代已经明显起作用，部分太古宙绿岩带由不同的构造单元拼合而成，并发育不同于显生宙蛇绿岩的大洋壳岩石组合，地幔柱在早太古代构造演化过程中起重要作用，是板块构造的重要补充机制，地球早期热产量较高，可能是造成板块规模较小，洋壳较厚，板块运动速度较快的原因，并以缓倾角俯冲为特征。     

中国天山花岗岩类的时空分布及构造意义

天山花岗岩类具明显的时空分带特征,以古生代最为明显.它们可分为:1.中天山南缘中加里东期花岗岩带:2.中天山北缘晚加里东期花岗岩带;3.中天山南缘早华力西期花岗岩带;4.中天山北缘中华力西期花岗岩带;5.马宗山南缘晚华力西期花岗岩带;6.南天山南坡晚华力西期花岗岩带.在时空上,花岗岩类在中天山陆壳南、北缘呈交替分布的格局,显示出与天山陆壳南、北张合呼应、交替演化的和谐一致关系.中天山花岗岩类是几个地槽主旋回的产物.天山花岗岩带与蛇绿岩带成“对”分布,沿“中天山南缘深断裂”,及“中国天山主干断裂”两侧延伸,二者互相平行.天山花岗岩类是多成因的.分为洋壳重熔型、陆壳重熔型及洋壳陆壳混合重熔型花岗岩.     

大别山南部的低级变质岩:宿松群和张八岭群

大别山南部的浅变质岩指宿松群和张八岭群。前者为扬子大陆被动边缘沉积,不整合在扬子大陆晚元古代的结晶基底之上,后者为古大别洋的洋壳,它和北部浅变质岩佛子岭群和梅山群一起,与洋壳俯冲造山带主要构造单元有良好的对应关系。     

Tectonic evolution of a composite collision orogen: An overview on the Qinling–Tongbai–Hong'an–Dabie–Sulu orogenic belt in central China

The formation of collisional orogens is a prominent feature in convergent plate margins. It is generally a complex process involving multistage tectonism of compression and extension due to continental subduction and collision. The Paleozoic convergence between the South China Block (SCB) and the North China Block (NCB) is associated with a series of tectonic processes such as oceanic subduction, terrane accretion and continental collision, resulting in the Qinling–Tongbai–Hong'an–Dabie–Sulu orogenic belt. While the arc–continent collision orogeny is significant during the Paleozoic in the Qinling–Tongbai–Hong'an orogens of central China, the continent–continent collision orogeny is prominent during the early Mesozoic in the Dabie–Sulu orogens of east-central China. This article presents an overview of regional geology, geochronology and geochemistry for the composite orogenic belt. The Qinling–Tongbai–Hong'an orogens exhibit the early Paleozoic HP–UHP metamorphism, the Carboniferous HP metamorphism and the Paleozoic arc-type magmatism, but the three tectonothermal events are absent in the Dabie–Sulu orogens. The Triassic UHP metamorphism is prominent in the Dabie–Sulu orogens, but it is absent in the Qinling–Tongbai orogens. The Hong'an orogen records both the HP and UHP metamorphism of Triassic age, and collided continental margins contain both the juvenile and ancient crustal rocks. So do in the Qinling and Tongbai orogens. In contrast, only ancient crustal rocks were involved in the UHP metamorphism in the Dabie–Sulu orogenic belt, without involvement of the juvenile arc crust. On the other hand, the deformed and low-grade metamorphosed accretionary wedge was developed on the passive continental margin during subduction in the late Permian to early Triassic along the northern margin of the Dabie–Sulu orogenic belt, and it was developed on the passive oceanic margin during subduction in the early Paleozoic along the northern margin of the Qinling orogen.Three episodes of arc–continent collision are suggested to occur during the Paleozoic continental convergence between the SCB and NCB. The first episode of arc–continent collision is caused by northward subduction of the North Qinling unit beneath the Erlangping unit, resulting in UHP metamorphism at ca. 480–490 Ma and the accretion of the North Qinling unit to the NCB. The second episode of arc–continent collision is caused by northward subduction of the Prototethyan oceanic crust beneath an Andes-type continental arc, leading to granulite-facies metamorphism at ca. 420–430 Ma and the accretion of the Shangdan arc terrane to the NCB and reworking of the North Qinling, Erlangping and Kuanping units. The third episode of arc–continent collision is caused by northward subduction of the Paleotethyan oceanic crust, resulting in the HP eclogite-facies metamorphism at ca. 310 Ma in the Hong'an orogen and low-P metamorphism in the Qinling–Tongbai orogens as well as crustal accretion to the NCB. The closure of backarc basins is also associated with the arc–continent collision processes, with the possible cause for granulite-facies metamorphism. The massive continental subduction of the SCB beneath the NCB took place in the Triassic with the final continent–continent collision and UHP metamorphism at ca. 225–240 Ma. Therefore, the Qinling–Tongbai–Hong'an–Dabie–Sulu orogenic belt records the development of plate tectonics from oceanic subduction and arc-type magmatism to arc–continent and continent–continent collision.     

浅变质岩在示踪大别—苏鲁造山带大陆板块俯冲与折返过程中的意义

中国大别-苏鲁造山带为大陆板块俯冲形成的碰撞造山带,该带北缘和内部产有原岩时代为新元古代-晚古生代的浅变质岩。这些浅变质岩对应于扬子板块北缘前寒武变质基底和扬子板块北缘古生代大陆架沉积物,形成过程于印支期扬子板块向北俯冲过程中的刮削作用密切相关,与大洋板块俯冲过程中刮削形成的加积楔具有类似的动力学过程。对大别-苏鲁造山带浅变质岩的深入研究,不仅有助于揭示大陆板块俯冲过程中高压-超高压岩石形成与折返过程,而且确定了扬子板块与华北板块之间的缝合线位置位于大别造山带北淮阳带的北部和苏鲁造山带的五莲-蓬莱群的北侧。     

西准噶尔蛇绿岩:古大洋俯冲增生过程的记录

蛇绿岩记录了大洋岩石圈形成、演化、消亡的全过程,是刻画区域板块构造和洋 陆格局演化的关键证据。本文通过系统梳理前人相关研究,总结西准噶尔蛇绿岩最新研究成果,探讨大陆地壳增生方式、恢复古大洋演化历史,从而对西准噶尔构造体制转化提供新制约。西准噶尔地区发育多条震旦纪—石炭纪被构造肢解的蛇绿岩带,具有典型的岩块 基质结构,绝大多数蛇绿岩包括正常洋壳组分和海山/大洋高原残片,其中基性岩具有MORB和OIB的地球化学特征。基于前人研究,本文认为在西准噶尔古大洋发育过程中,发育不同时代与地幔柱有关的海山/大洋高原,同时存在增生型和侵蚀型两类汇聚板块边界。另外,大洋高原增生不仅是大陆地壳增生的有效途径之一,还可能诱发俯冲极性反转和传递。而在大洋高原形成初期,还可能存在地幔柱诱发俯冲起始机制。