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1.
通过同构造沉积物质记录了解物源区剥蚀作用过程进而探索盆山构造相互关系,是大陆构造动力学研究的一个重要方面。砂岩骨架成分分析和重矿物及部分标型矿物分析方法,已被较多地用来探索新疆天山造山带与其南部库车盆地晚中生代以来的相互关系和构造演变过程,但是关于中生代较早时期库车盆地构造属性及北部造山带隆升剥蚀过程的认识仍存在较大分歧。本文运用电子探针微区成分分析方法,对库车盆地北缘中段晚三叠世和早侏罗世砂岩中具代表性的15个砂岩样品中的38颗碎屑长石和26颗碎屑白云母矿物进行了矿物化学成分分析。结果表明,长石主要来自变质岩物源区,25颗碎屑白云母均属多硅白云母,表明其源区岩石曾经历了高压变质作用。这些多硅白云母中Si原子含量显示它们比目前保留在天山造山带高压变质带蓝片岩和榴辉岩中的多硅白云母形成的压力要低,可能反映了源区高压变质岩的正常剥露顺序。这项研究结果表明,至少在晚三叠世-早侏罗世时期,库车盆地北部天山造山带中的高压变质岩已经剥露于地表并遭受剥蚀成为物源供给区。具体是中天山南缘早古生代高压变质带还是晚古生代南天山高压变质带作为重要物源区,尚需进一步的研究工作。 相似文献
2.
CHEN Wei‐Min HUANG Young‐Ching Yoshiyuki IIZUKA LO Ching‐Hua WU Hanquan SONG Shuguang YANG Jingsui XU Zhiqin YANG Houng‐Yi 《《地质学报》英文版》2002,76(1):44-62
After the integration of petrographic study, geothermobarometry and Gibbs method, the synthetic P-T paths for the rocks from different geological profiles in the North Qilian, China, have been derived. The composite P-T paths from different methods indicate that all the high-pressure rocks in the Qilian area recorded P-T paths with clockwise loops starting at the blueschist facies, later reaching peak metamorphism at the blueschist facies, eclogite fades or epidote-amphibolite facies and ending up with the greenschist facies. The incremental Ar-Ar dating shows that the plateau ages for the high-pressure rocks range from 410 to 443 Ma. The plateau ages could be used as a minimum age constraint for the subduction that resulted in the formation of these high-pressure rocks in the Qilian area. It is proposed that the late-stage decompressional and cooling P-T paths with ends at the greenschist facies for these high-pressure rocks probably reflect the uplift process which could occur after shifting the arc-t 相似文献
3.
西天山的增生造山过程 总被引：63，自引：2，他引：61
西天山位于中亚造山带的西南缘,经历了复杂的增生造山过程。它也是标志塔里木地块北部被动陆缘与西伯利亚地块南侧宽阔活动陆缘最后拼合的构造带。根据近年来的研究进展,将西天山划分为北天山弧增生体、伊犁地块北缘活动陆缘、伊犁地块、伊犁地块南缘活动陆缘、中天山复合弧地体、西天山（高压）增生楔和塔里木北部被动大陆边缘。同时综述了西天山蛇绿岩、高压变质岩、花岗岩类的年代学新资料,讨论了其增生造山的过程。西天山增生造山与早古生代帖尔斯克依古洋、早古生代晚期—晚古生代南天山洋和晚古生代北天山洋3个代表洋盆的演化相关,增生造山结束的时间可能是早石炭世末。二叠纪时期,西天山至整个中亚地区进入后碰撞演化阶段。现有资料证实西天山为晚古生代增生造山带,并非三叠纪碰撞造山带。 相似文献
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The late Palaeozoic western Tianshan high‐pressure /low‐temperature belt extends for about 200 km along the south‐central Tianshan suture zone and is composed mainly of blueschist, eclogite and epidote amphibolite/greenschist facies rocks. P–T conditions of mafic garnet omphacite and garnet–omphacite blueschist, which are interlayered with eclogite, were investigated in order to establish an exhumation path for these high‐pressure rocks. Maximum pressure conditions are represented by the assemblage garnet–omphacite–paragonite–phengite–glaucophane–quartz–rutile. Estimated maximum pressures range between 18 and 21 kbar at temperatures between 490 and 570 °C. Decompression caused the destabilization of omphacite, garnet and glaucophane to albite, Ca‐amphibole and chlorite. The post‐eclogite facies metamorphic conditions between 9 and 14 kbar at 480–570 °C suggest an almost isothermal decompression from eclogite to epidote–amphibolite facies conditions. Prograde growth zoning and mineral inclusions in garnet as well as post‐eclogite facies conditions are evidence for a clockwise P–T path. Analysis of phase diagrams constrains the P–T path to more or less isothermal cooling which is well corroborated by the results of geothermobarometry and mineral textures. This implies that the high‐pressure rocks from the western Tianshan Orogen formed in a tectonic regime similar to ‘Alpine‐type’ tectonics. This contradicts previous models which favour ‘Franciscan‐type’ tectonics for the southern Tianshan high‐pressure rocks. 相似文献
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矿床是大地构造演化的重要指示标志,矿床特征和时空分布格局为重建东天山地区大地构造演化提供了新的制约。研究表明,夹于吐哈地块和中天山地块之间的东天山古生代造山带,在空间上可分为吐哈盆地南缘铜矿带(北带)、康古尔金矿带(中带)和阿齐山—雅满苏铁(铜)-银多金属矿带(南带)3个不同的构造-地层(岩浆)-成矿带。在时间上东天山造山带具有明显的三阶段演化性:(1)吐哈盆地南缘奥陶—泥盆纪为活动大陆边缘,形成了包括VMS型铜锌矿床和斑岩型铜矿床在内的古陆缘成矿系统;晚泥盆世末—早石炭世初古洋壳向北俯冲关闭,中天山地块增生拼贴到吐哈地块(属哈萨克斯坦—准噶尔板块组成部分)南缘。(2)早石炭世(维宪期)沿康古尔缝合带再次拉张,形成石炭纪裂陷槽火山-沉积岩系及相应的层控成矿系统(VMS型铜锌矿床、火山岩型铁(铜)矿床、自然铜矿床),裂陷槽封闭过程中发育了夕卡岩型银多金属矿床。(3)早二叠世形成与幔源岩浆底侵作用有关、跨构造单元发育的铜镍硫化物成矿系统和与剪切活动有关的金矿床。依据上述认识,对东天山地区的矿产勘查提出了新建议。 相似文献
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变质地质学新领域——超高压变质作用与地球动力学 总被引：1，自引：0，他引：1
简要总结了近年在欧亚大陆发现的超高压变质岩地质产状，岩石类型，结晶条件和构造位置等基本特片，对超高压变质作用及其地球动力学机制的研究现状及存在的问题进行了评述，基于对大别－苏鲁超高压变质带的研究成果，认为超高压变质作用可能是新型的区域变质作用，而目前所建立的任何一种地球动力学模型都不完善，建议今后在岩石学和矿物学研究基础上，加强对超高压变质杂岩的地球化学，构造地质学，实验岩石学及地球物理学等方面的 相似文献
7.
西南天山造山带是塔里木板块和伊犁-中天山板块聚合碰撞的产物,经历了长期复杂的演化.伊犁-中天山陆块南缘的变质作用研究对于揭示西南天山的地质演化历史具有重要意义.这一地区变质岩分布广泛,但目前的变质作用研究主要集中于木扎尔特的高级变质岩,位于同一构造带上其他变质岩的演化和分布特点缺少详细的研究,尚不清楚它们是作为高温变质带的一部分还是来自造山带的其他构造单元.针对该问题,在详细的岩相学分析基础上,利用碳质拉曼光谱（Raman spectroscopy of carbonaceous material,RSCM）温度计对木扎尔特东侧的阿克牙孜河下游地区多个剖面开展了变质温度研究.根据结构构造特征将这些岩石分为具有变余沉积结构构造且发生不同程度糜棱岩化的浅变质碎屑岩-碳酸盐岩系列和具有变质结晶结构的片岩-变粒岩系列.RSCM温度计显示前者经历的峰期温度为465~597℃,原岩很可能为卷入造山带的石炭纪地层,抬升过程中局部发生糜棱岩化.后者峰期温度为552~617℃,绿片岩相叠加期间发生C-O-H流体活动,可能属于伊犁-中天山的变质基底那拉提岩群.研究表明,伊犁-中天山南缘的阿克牙孜下游一带的变质岩具有不同的变质演化历史,它们来自不同的构造单元,并不是木扎尔特高温变质带的延续. 相似文献
8.
Paleozoic Accretion-Collision Events and Kinematics of Ductile Deformation in the Eastern Part of the Southern-Central Tianshan Belt, China 总被引：3，自引：0，他引：3
The Tianshan range could have been built by both late Early Paleozoic accretion and Late Paleozoic collision events. The late Early Paleozoic Aqqikkudug-Weiya suture is marked by Ordovician ophiolitic melange and a Silurian flysch sequence, high-pressure metamorphic relics, and mylonitized rocks. The Central Tianshan belt could principally be an Ordovician volcanic arc; whereas the South Tianshan belt, a back-arc basin. Macro- and microstructures, along with unconformities, provide some kinematic and chronological constraints on 2-phase ductile deformation. The earlier ductile deformation occurring at ca. 400 Ma was marked by north-verging ductile shearing, yielding granulite-bearing ophiolitic melange blocks and garnet-pyroxene-facies ductile deformation, and the later deformation, a dextral strike-slip tectonic process, occurred during the Late Carboniferous-Early Permian. Early Carboniferous molasses were deposited unconformably on pre-Carboniferous metamorphic and ductilely sheared rocks, implying t 相似文献
9.
《地学前缘(英文版)》2020,11(3):915-924
Knowing the phase relations of carbon-bearing phases at high-pressure(HP) and high-temperature(HT) condition is essential for understanding the deep carbon cycle in the subduction zones.In particular,the phase relation of carbon-bearing phases is also strongly influenced by redox condition of subduction zones,which is poorly explored.Here we summarized the phase relations of carbon-bearing phases(calcite,aragonite,dolomite,magnesite,graphite,hydrocarbon) in HP metamorphic rocks(marble,metapelite,eclogite) from the Western Tianshan subduction zone and high-pressure experiments.During prograde progress of subduction,carbonates in altered oceanic crust change from Ca-carbonate(calcite) to Ca,Mg-carbonate(dolomite),then finally to Mgcarbonate(magnesite) via Mg-Ca cation exchange reaction between silicate and carbonate,while calcite in sedimentary calcareous ooze on oceanic crust directly transfers to high-pressure aragonite in marble or amorphous CaCO3 in subduction zones.Redox evolution also plays a significant effect on the carbon speciation in the Western Tianshan subduction zone.The prograde oxygen fugacity of the Western Tianshan subduction zone was constrained by mineral assemblage of garnet-omphacite from FMQ-1.9 to FMQ-2.5 at its metamorphic peak(maximum P-T) conditions.In comparison with redox conditions of other subduction zones,Western Tianshan has the lowest oxygen fugacity.Graphite and light hydrocarbon inclusions were ubiqutously identified in Western Tianshan HP metamorphic rocks and speculated to be formed from reduction of Fe-carbonate at low redox condition,which is also confirmed by high-pressure experimental simulation.Based on petrological observation and high-pressure simulation,a polarized redox model of reducing slab but oxidizing mantle wedge in subduction zone is proposed,and its effect on deep carbon cycle in subduction zones is further discussed. 相似文献
10.
西南天山高压-超高压变质带是世界上少有的经历深俯冲的增生杂岩带,是古天山洋向北俯冲的结果。针对该俯冲杂岩带内部结构的研究目前仍存在争论。本文以木扎尔特地区一条长约4 km的南北向剖面为例,对西南天山高压-超高压变质带的野外特征、矿物学和变质演化研究进行了综述。目前的研究表明,木扎尔特地区存在超高压和高压两类硬柱石榴辉岩,但绝大部分都经历了强烈的退变质和变形改造,被蓝片岩相或绿片岩相矿物组合取代。这些变基性岩在空间上构成北部和南部两个榴辉岩带,二者为构造接触。木扎尔特超高压硬柱石榴辉岩与其围岩经历相似的峰期压力,构成西南天山超高压带的西端。与东侧阿克牙孜地区超高压榴辉岩相比,它们在变形特征、岩石组合和变质演化方面表现出一定的独特性,很可能说明深俯冲板片在折返过程中沿构造带走向存在差异变质-变形演化。这些基础研究对全面认识冷俯冲增生杂岩带的变质演化及其俯冲和折返的地球动力学机制具有重要意义。 相似文献
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北祁连造山带是早古生代大洋板块"冷"俯冲的典型地区,形成了一系列高压低温变质的岩石组合.基性榴辉岩是俯冲洋壳变质的产物,根据其结构构造特征可以划分为(1)粒状榴辉岩,峰期变质矿物组合为Grt+Omp+Phn+Rut±Lws,硬柱石呈包裹体和假象分布于石榴石内,变质温压条件T=465～508℃,P=2.30～2.60GPa.(2)片状榴辉岩,岩石具片状构造,其共生矿物组合Omp+Czo/Ep+Phn+Gln构成透入性面理S1和线理L1,以及宏观和显微同斜褶皱F1.其峰期变质温压条件为T=466～510℃,P=1.9～2.2GPa.(3)蓝片岩相退化变质榴辉岩,蓝片岩相变质矿物Gln+Ep+Phn±Ab强烈交代榴辉岩相矿物,并发生强烈D2期变形作用,岩石形成明显的透入性面理S2和线理L2,以及同斜剪切褶皱F2.蓝闪石和多硅白云母线理的统计揭示D2期变形以斜向走滑剪切为主,与D1期变形的榴辉岩的运动学特征大体相似.D2同变质的温压条件为T=422～487℃,P=1.15～1.37GPa.高压变质带晚期的绿片岩相叠加和D3期变形,形成透入性面理S3和线理L3,其运动特征为近于垂直构造线的逆冲剪切.结合榴辉岩变形特征,变质温压条件和同位素年代学资料,我们认为退变质的强弱与变形程度有密切关系.峰期变质后的榴辉岩经过早期绿帘石榴辉岩相到蓝片岩相斜向走滑剪切,和晚期绿片岩相逆冲,在泥盆纪早期快速折返的出露地表. 相似文献
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Recently, a huge ultrahigh‐pressure (UHP) metamorphic belt of oceanic‐type has been recognized in southwestern (SW) Tianshan, China. Petrological studies show that the UHP metamorphic rocks of SW Tianshan orogenic belt include mafic eclogites and blueschists, felsic garnet phengite schists, marbles and serpentinites. The well‐preserved coesite inclusions were commonly found in eclogites, garnet phengite schists and marbles. Ti‐clinohumite and Ti‐chondrodite have been identified in UHP metamorphic serpentinites. Based on the PT pseudosection calculation and combined U‐Pb zircon dating, the P‐T‐t path has been outlined as four stages: cold subduction to UHP conditions before ～320 Ma whose peak ultrahigh pressure is about 30 kbar at 500oC, heating decompression from the Pmax to the Tmax stage before 305 Ma whose peak temperature is about 600oC at 22kbar, then the early cold exhumation from amphibolite eclogite facies to epidote‐amphibolite facies metamorphism characterized by ITD PT path before 220 Ma and the last tectonic exhumation from epidote amphibolite facies to greenschist facies metamorphism. Combining with the syn‐subduction arc‐like 333‐326 Ma granitic rocks and 280‐260 Ma S‐type granites in the coeval low‐pressure and high‐temperature (LP‐HT) metamorphic belt, the tectonic evolution of Tianshan UHP metamorphic belt during late Cambrian to early Triassic has been proposed. 相似文献
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造山带中成对出现的高压麻粒岩与榴辉岩及其地球动力学意义 总被引：18，自引：13，他引：5
在一些典型碰撞造山带中,高压麻粒岩与榴辉岩在空间和时间上密切相关,它们之间的关系对揭示碰撞造山带的造山过程和造山机制具有重要意义.本文以中国西部的南阿尔金、柴北缘及中部的北秦岭造山带为例,详细陈述了这3个地区榴辉岩和相关的高压麻粒岩的野外关系、变质演化和形成时代,目的是要建立大陆碰撞造山带中榴辉岩和相关高压麻粒岩形成的地球动力学背景模式.南阿尔金榴辉岩呈近东西向分布在江尕勒萨依,玉石矿沟一带,与含夕线石副片麻岩、花岗质片麻岩和少量大理岩构成榴辉岩一片麻岩单元,榴辉岩中含有柯石英假象,其峰期变质条件为P=2.8～3.0GPa,T=730～850℃,并在抬升过程中经历了角闪岩-麻粒岩相的叠加;大量年代学研究显示其峰期变质时代为485～500Ma.南阿尔金高压麻粒岩分布在巴什瓦克地区,包括高压基性麻粒岩和高压长英质麻粒岩,它们与超基性岩构成了一个大约5km宽的构造岩石单元,与周围角闪岩相的片麻岩为韧性剪切带接触.长英质麻粒岩和基性麻粒岩的峰期组合均具有蓝晶石和三元长石(已变成条纹长石),形成的温压条件为T=930～1020℃,P=1.8～2.5GPa,并在退变质过程中经历了中压麻粒岩相变质作用叠加.锆石SHRIMP测定显示巴什瓦克高压麻粒岩的峰期变质时代为493～497Ma.都兰地区的榴辉岩分布柴北缘HP-UHP变质带的东端,在榴辉岩和围岩副片麻岩中均发现有柯石英保存,形成的峰期温压条件为T=670～730℃和P=2.7～3.25GPa,退变质阶段经过了角闪岩相的叠加;榴辉岩相变质时代为420～450Mao都兰地区的高压麻粒岩分布在阿尔茨托山西部,高压麻粒岩包括基性麻粒岩长英质麻粒岩,基性麻粒岩的峰期矿物组合为Grt+Cpx+Pl±Ky±Zo+Rt±Qtz,长英质麻粒岩的峰期矿物组合为：Grt+Kf+Ky+Pl+Qtz.峰期变质条件为T=800～925℃,P=1.4～1.85GPa,退变质阶段经历了角闪岩-绿片岩的改造,高压麻粒岩的变质时代为420～450Ma.北秦岭榴辉岩分布在官坡-双槐树一带,榴辉岩的峰期变质组合为Grt+Omp±Phe+Qtz+Rt,所计算的峰期温压条件为T=680～770℃和P=2.25～2.65GPa,年代学数据显示榴辉岩的变质时代为500Ma左右.北秦岭高压麻粒岩分布在含榴辉岩单元的南侧松树沟一带,包括高压基性麻粒岩和高压长英质麻粒岩,与超基性岩在空间上密切伴生,高压麻粒岩的峰期温压条件为T=850～925℃,P=1.45～1.80GPa,锆石U-Pb年代学研究显示其峰期变质时代为485～507Ma.以上三个实例显示,出现在同一造山带、在空间上伴生的高压麻粒岩和榴辉岩有各自不同的变质演化历史,但榴辉岩中的榴辉岩相变质时代和相邻的高压麻粒岩中的高压麻粒岩相变质作用时代相同或相近,这种成对出现的榴辉岩和高压麻粒岩代表了它们同时形成在造山带中不同的构造环境中,即榴辉岩的形成于大陆俯冲带中,而高压麻粒岩可能形成在俯冲带之上增厚的大陆地壳根部. 相似文献
15.
松多榴辉岩是约束拉萨板块中部古特提斯洋演化的重要材料,前人对其形成年代、变质P-T轨迹等诸多方面已进行了详细的研究,然而对其原岩的研究却较为薄弱,地球化学分析是恢复榴辉岩原岩的重要手段,也是反演区域古特提斯洋演化的重要依据.在系统收集区域地球化学数据的基础上,采集了17件松多榴辉岩样品,进行了地球化学研究,意在对区域构造演化提供新的制约.松多地区主要出露双矿物榴辉岩和退变质榴辉岩,两类榴辉岩都表现出亚碱性拉斑玄武岩的特征,在微量元素和各类构造环境判别图解中,两种榴辉岩分别都落入了N-MORB和E-MORB区域.基于上述分析结果,并结合区域地质资料,表明松多古特提斯洋在演化过程中可能长期存在地幔柱岩浆和正常洋中脊亏损地幔岩浆的相互作用. 相似文献
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羌塘中部高压变质带是目前青藏高原内部延伸规模最大的高压变质带,是理解特提斯演化的关键地质记录。高压变质带主要沿龙木措-双湖-澜沧江缝合带一线出露,主要由榴辉岩、蓝片岩、石榴子石多硅白云母片岩及少量高压麻粒岩组成。其中,榴辉岩主要出露于戈木、果干加年山、冈玛错、巴青及滇西的勐库地区,主要呈透镜状产于石榴子石多硅白云母片岩中。除巴青地区的榴辉岩外,其余地区榴辉岩的峰期变质温度较低且含有硬柱石及其假象,峰期变质条件位于硬柱石榴辉岩相稳定区域,是洋壳冷俯冲的产物。虽然对于戈木地区榴辉岩锆石成因仍有争议,但已有资料显示,羌塘中部高压变质带主体变质时代集中在晚三叠世,其相关高压变质岩石的折返可能与洋盆的闭合及随后的陆-陆碰撞相关。近期研究表明,羌塘中部可能存在二叠纪低温高压变质岩,折返于大洋俯冲阶段,可能与洋岛或海山的俯冲及引发的俯冲侵蚀作用相关。此外,羌塘香桃湖地区出露早古生代的基性高压麻粒岩,是冈瓦纳大陆北缘陆块拼贴的记录。因此,对羌塘中部高压变质带进行进一步系统的研究工作,对于深入理解冈瓦纳北缘构造演化及古特提斯的俯冲与闭合过程具有重要的意义。 相似文献
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Yamirka Rojas-Agramonte Daniel Herwartz Antonio García-Casco Alfred Kröner Dmitriy V. Alexeiev Reiner Klemd Stephan Buhre Matthias Barth 《Contributions to Mineralogy and Petrology》2013,166(2):525-543
High-pressure and ultrahigh-pressure (UHP) eclogite-bearing metamorphic assemblages in the North Tianshan of Kyrgyzstan are known from the Aktyuz and Makbal areas, where eclogites and garnet amphibolites are associated with continental rocks such as granitoid gneisses in Aktyuz and shallow-water clastic (passive margin?) metasediments in Makbal. We present the first Lu–Hf isotope data for an eclogite and two garnet amphibolite samples from the two metamorphic terranes which, combined with petrological analysis, tightly constrain the age of high-pressure metamorphism in the Kyrgyz North Tianshan. A five-point isochron for an Aktyuz eclogite sample provides a Lu–Hf age of 474.3 ± 2.2 Ma, and a four-point isochron on a Makbal sample corresponds to 470.1 ± 2.5 Ma. A prograde, subduction-related path is inferred for both samples with peak P–T conditions ranging from 1.4 to 1.6 GPa and 610–620 °C. A further Makbal sample provided a significantly older Lu–Hf age of 486 ± 5.4 Ma, most likely due to late alteration in the sample (late addition of unradiogenic Hf). We conclude that garnet growth in all three samples occurred around ca. 474 Ma and that these rocks likely experienced UHP metamorphism contemporaneously. Our results support previous geochronological evidence for an Early Ordovician collision belt in the North Tianshan and allow refinement of a tectonic model involving subduction of thinned continental crust to considerable depth along the margin of a small microcontinent. 相似文献
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南天山金矿带是世界上一个重要的金矿资源地,产出数个超大型金矿。这些矿床有许多共同点:如大地构造背景、构造环境、含矿岩系、容矿岩石、控矿构造、矿体形态、矿石类型、主要金属矿物、载金矿物、围岩蚀变、成矿时代和成矿方式等相似。但是,进一步分析可以发现他们之间也存在一定差异。例如,在构造位置、物质成分、围岩蚀变等方面存在差异。对本区一些基本的成矿特征进行分析后,认为矿带的形成与南天山造山带的形成和演化关系密切,华力西期与花岗岩活动有关的热液成矿作用应是主要的成矿作用。因此,该矿带应属于细脉浸染型金矿较为合适。南天山尚有寻找此类金矿的远景。 相似文献
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羌塘中部的高压变质带位于龙木错—双湖—澜沧江板块缝合带之上,由榴辉岩、蓝片岩和石榴石白云母片岩组成。其形成过程对探讨板块缝合带的构造演化具有重要意义。2008年笔者在果干加年山地区的展金岩群湖南山岩组中发现了硬玉石榴石二云母片岩这种新的高压变质岩石类型,文中以其为研究对象,做了较为详细的岩石学、矿物学以及变质作用的研究,认为硬玉石榴石二云母片岩至少经历了二期的变质作用:第一期早期绿片岩相,形成了片理S1,其pT条件为T=425～434℃,p=300～500MPa;第二期主期蓝片岩相高压变质作用,形成岩石主期片理S2,其pT条件为T=472～481℃,p=1200～1700MPa。硬玉石榴石二云母片岩是榴辉岩折返过程中构造事件的产物,这期折返事件形成了218～220Ma的一期蓝片岩相变形-变质作用。 相似文献