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1.
琼中基性麻粒岩是海南岛高级变质杂岩中最重要的组成部分之一,对其深入研究可为客观恢复海南岛晚古生代—早中生代构造演化历史、查明古特提斯洋向东如何延伸等基础地质问题提供新的制约。本次研究以琼中地区出露的基性麻粒岩为研究对象,对基性麻粒岩中锆石采用内部矿物包体自动矿物分析系统(TIMA)扫描、阴极发光图像照相、LA- ICP- MS U- Pb定年与稀土元素分析等综合研究发现,琼中基性麻粒岩中锆石可划分为岩浆锆石和变质锆石两类;30个岩浆锆石测点206Pb/238U年龄介于245~230 Ma之间,相应的加权平均年龄为238±2 Ma(MSWD=0. 38),应代表琼中基性麻粒岩的原岩时代;24个变质锆石测点206Pb/238U年龄介于243~231 Ma之间,其加权平均年龄为237±2 Ma(MSWD=1. 70),代表琼中基性麻粒岩的变质时代。综合海南岛已发表的相关数据,琼中基性麻粒岩原岩形成时代与变质时代均为三叠纪,而不是前人所认为的中元古代,其形成可能与古特提斯洋闭合后印支陆块、华南陆块在碰撞造山后伸展垮塌阶段的岩浆- 变质作用有关。  相似文献   

2.
本文通过几何学与运动学等构造变形分析, 勾勒出南秦岭佛坪地区龙草坪混合岩化片麻岩穹隆、佛坪县城片麻岩穹隆以及秧田坝—十里铺走滑剪切带的基本形态。同时, 对该区混合岩、麻粒岩以及变形花岗岩进行了系统的岩石学与年代学研究。结果表明, 混合岩的锆石具有明显的核-边结构, 其中中色体年龄集中在(211.8±1.9) Ma, 浅色体中锆石边部年龄为(203.7±1.6) Ma, 而继承核部则显示了与本地区泥盆纪变质沉积岩中碎屑锆石一致的年龄谱系。麻粒岩的锆石也具有明显的核-边结构, 核与边分别得到(201.5±7.0) Ma和(188.1±1.5) Ma的加权平均年龄。伟晶岩和细粒花岗岩样年龄分别为(200.4±2.0) Ma和(201.1±1.5) Ma, 误差范围内一致。穹隆一带的副片麻岩和走滑剪切带南侧变质沉积岩分别得到(198.1±2.2) Ma和(196.1±2.1) Ma的变质年龄。佛坪县城片麻岩穹隆一带的变形花岗岩年龄为(205.5±3.0) Ma。综合以上构造变形与变质-深熔-岩浆作用的研究, 我们构建了佛坪地区早中生代构造演化序列, 并提出片麻岩穹隆侵位过程中得到了作为勉略带东侧部分的秧田坝—十里铺韧性走滑剪切带活动的促进。并认为南秦岭构造带至少在217~212 Ma之前仍处于俯冲环境, 于211~201 Ma进入同碰撞背景, 并于200~190 Ma完成同碰撞向伸展体制的转变。  相似文献   

3.
本文采用LA-ICP-MS技术,对胶北地体TTG片麻岩和花岗质片麻岩中锆石进行系统原位U-Pb定年和稀土、微量元素的分析,发现研究区早前寒武变质结晶基底存在多期岩浆-变质热事件。4件TTG片麻岩和2件花岗质片麻岩锆石样品记录了2909±13Ma、2738±23Ma、2544±15~2564±12Ma和2095±12Ma 4组岩浆事件年龄,以及2504±16~2513±32Ma和1863±41Ma 2组变质事件年龄。结合以往TTG片麻岩和花岗质片麻岩的地球化学及Nd同位素研究发现,约2738Ma的TTG岩浆事件可能代表胶北地体地壳最主要的生长事件,而2544~2564Ma的岩浆事件则可能代表古老地壳重熔的最强烈岩浆事件,约2095Ma岩浆事件则反映了胶-辽-吉构造带内部在该时期与地壳拉张作用有关的岩浆活动。2504~2513Ma是研究区以及华北克拉通早前寒武基底最主要的一期变质热事件,可能与地幔柱(热点)岩浆的底侵作用有关,而TTG片麻岩记录的约1863Ma的变质年龄与研究区基性和泥质高压麻粒岩相岩石记录的麻粒岩相变质时代一致,暗示TTG片麻岩可能也经历了古元古代高压麻粒岩相变质作用,上述研究进一步表明胶北地体在古元古代的确存在一期陆-陆碰撞的重要造山事件。该项研究成果对于进一步深入探讨胶北乃至华北克拉通早前寒武纪变质基底的形成演化、岩浆-变质热事件序列及其构造背景具有重要的科学意义。  相似文献   

4.
北秦岭造山带的早古生代多期变质作用   总被引:2,自引:13,他引:2  
张建新  于胜尧  孟繁聪 《岩石学报》2011,27(4):1179-1190
北秦岭造山带的秦岭岩群以高级变质岩石为特征,主要包括少量榴辉岩、高压麻粒岩和区域上广泛分布的麻粒岩-角闪岩相变质岩石。年代学研究显示秦岭岩群中不同岩石记录了多期变质作用。已有的定年资料给出北秦岭官坡地区的榴辉岩的年龄为500Ma左右,代表榴辉岩相的变质时代。结合岩相学资料,对两个高压麻粒岩样品的SHRIMP和LA-ICPMS U-Pb测定分别获得504±7Ma 和506±3Ma的年龄,应代表高压麻粒岩相变质时代。这表明高压麻粒岩和相邻的榴辉岩有相近的变质时代,但形成在造山带中不同的构热造环境中。西峡地区的角闪二辉麻粒岩的U-Pb定年给出两组早古生代年龄,一组为440±2Ma,可能代表了中低压麻粒岩相的变质时代,另一组为426±1Ma,应代表区域角闪岩相的变质时代。桐柏山北部的石榴二辉麻粒岩的U-Pb定年数据给出436±1Ma的年龄,为中压麻粒岩相的变质时代。这些资料表明北秦岭造山带经历了早奥陶世的俯冲和地壳增厚作用,并在晚志留世遭受了广泛的巴罗式区域变质作用。  相似文献   

5.
辽东清原地区太古代岩石Rb—Sr年代   总被引:3,自引:0,他引:3  
清原地区太古界岩石和矿物的Rb-Sr研究给出五个等时线年龄:2924±325Ma(城子疃组麻粒岩),2625±376Ma(通什村组麻粒相岩石),2359±81Ma(线金厂紫苏花岗岩),2366±48Ma(斗虎屯附近混合岩中的包体角闪岩),1639±49Ma(城子疃组麻粒岩的分离矿物)。根据等时线和模式年龄推断:城子疃组和通什村组的火成原岩年龄分别为2900—2800Ma和2600Ma;紫苏花岗岩侵位和麻粒岩相变质作用几乎同时发生于2600Ma前;2360Ma前发生广泛的混合岩化;1640Ma前有后期变质作用叠加。  相似文献   

6.
南秦岭佛坪地区麻粒岩相岩石锆石U-Pb年龄   总被引:17,自引:0,他引:17  
对南秦岭佛坪地区麻粒岩相岩石中锆石的特征进行了详细的研究和U-Pb同位素年龄测定。中酸性麻粒岩中3个变质成因锆石的~(256)Pb/~(238)U表面年龄统计权重平均值(谐和年龄)为221.4±3.6Ma,是这些变质锆石较为准确的生成年龄;该样品4个锆石颗粒组成的不一致线上、下交点年龄分别为822±272Ma和218±14Ma;石榴夕线黑云片麻岩中4个锆石颗粒构成的不一致线的上下交点年龄分别为2283±162Ma和271±15Ma。两个样品的数据点均比较靠近下交点而远离上交点,其上交点年龄不具明确地质意义。综合各方面因素,认为麻粒岩相峰变质作用时代为印支期—海西晚期(220~270Ma左右),这是迄今为止秦岭地区所报道过的最年轻的麻粒岩地质体。  相似文献   

7.
南秦岭佛坪地区麻粒岩相岩石锆石U—Pb年龄   总被引:3,自引:0,他引:3  
杨崇辉  魏春景 《地质论评》1999,45(2):173-179
对南秦岭佛坪地区麻粒岩相岩石中锆石的特征进行了详细的研究和U-Pb同位素年龄测定。中酸性麻粒岩中3个变质成因锆石的~(256)Pb/~(238)U表面年龄统计权重平均值(谐和年龄)为221.4±3.6Ma,是这些变质锆石较为准确的生成年龄;该样品4个锆石颗粒组成的不一致线上、下交点年龄分别为822±272Ma和218±14Ma;石榴夕线黑云片麻岩中4个锆石颗粒构成的不一致线的上下交点年龄分别为2283±162Ma和271±15Ma。两个样品的数据点均比较靠近下交点而远离上交点,其上交点年龄不具明确地质意义。综合各方面因素,认为麻粒岩相峰变质作用时代为印支期—海西晚期(220~270Ma左右),这是迄今为止秦岭地区所报道过的最年轻的麻粒岩地质体。  相似文献   

8.
北大别片麻岩的超高压变质证据——来自锆石提供的信息   总被引:10,自引:1,他引:10  
本文对北大别片麻岩锆石中矿物包体及年代学进行了研究,首次发现了北大别片麻岩的超高压变质作用证据。结合阴极发光图像和同位素定年,片麻岩锆石中矿物包体组合至少可分出三期:(1)原岩岩浆矿物组合,即斜长石、黑云母、石英和磷灰石;(2)超高压变质矿物组合,即金刚石、石榴子石和金红石等;(3)麻粒岩相退变质矿物组合,如透辉石等。其中,金刚石和石榴子石主要以包体形式被包裹于透辉石中,而透辉石是北大别麻粒岩相退变质阶段形成的代表性矿物。锆石SHRIMP U-Pb定年结果表明,北大别片麻岩的峰期变质时代和麻粒岩相退变质时代分别为218±3Ma和199±10Ma。这些证明北大别片麻岩,如同其中的榴辉岩一样,经过了印支期超高压变质作用。  相似文献   

9.
为了搞清大别山地区高压麻粒岩和高压超高压榴辉岩的关系,了解大别山地区加里东期构造-热事件的性质和特征,探索大别造山带的区域延伸和对比等,选择大别山东部惠兰山麻粒岩及安徽太湖石马榴辉岩的直接围岩——含榴斜长片麻岩进行了同位素年代学研究。惠兰山麻粒岩呈似层状夹于长英质片麻岩中,岩性为石榴角闪二辉麻粒岩,其峰变质条件t=682~880℃;P=0.9~1.29 GPa,峰变质压力与大别山西部熊店加里东期榴辉岩相当。惠兰山麻粒岩存在两类不同晶形特征和不同成因的锆石。其中长柱状锆石用~(207)Pb/~(206)Pb蒸发法给出平均年龄443±23 Ma,代表了麻粒岩相峰变质年龄;浑圆粒状锆石用同样方法给出的年龄为2300±15 Ma,可能反映麻粒岩原岩形成年龄或前期变质事件的时代。石马含榴斜长片麻岩  相似文献   

10.
中国与蒙古之地质   总被引:26,自引:0,他引:26  
东昆仑中部缝合带清水泉一带发育石榴斜长紫苏麻粒岩、紫苏辉石黑云母石榴子石麻粒岩、石榴二辉斜长麻粒岩和石榴单斜辉石麻粒岩,它们与混合岩化黑云母石榴子石变粒岩、黑云母辉石变粒岩、石墨大理岩、含透辉石透闪石大理岩、透辉石大理岩、黑云斜长角闪岩和片麻岩等高级变质岩系以及纯橄岩、辉橄岩、橄长岩、辉长岩、辉绿岩和玄武岩等共同构成蛇绿混杂岩。麻粒岩相变质作用的温压条件为T=760~880℃,p=830~1200MPa,为高温中高压麻粒岩相变质作用,估算其形成深度为40~45km。麻粒岩相变质作用的SHRIMP锆石U-Pb年龄为(507·7±8·3)Ma。清水泉地区蛇绿岩形成于~520Ma,到~508Ma时俯冲至地下40~45km深处而发生中高压麻粒岩相变质作用,然后发生构造折返而剥露至地表。证实了清水泉高级变质岩和基性—超基性岩片是形成于早—中寒武世的蛇绿混杂岩,标志一个古生代早期的非常重要的板块汇聚边界,这对于进一步研究东昆仑造山带构造演化、乃至中国西部大地构造格局具有非常重要的意义。  相似文献   

11.
海南岛几个重大基础地质问题的探讨   总被引:25,自引:0,他引:25  
张业明  徐安武 《地质论评》1998,44(6):568-575
海南岛有无泥盆纪地层?有无加里东运动?有无加里东期花岗岩?历来是大家关注和争论的焦点问题。在1:5万昌江县幅和邦溪幅地质调查研究中,笔者对上述问题进行了探讨,并取得了一些重要进展:首次在海南岛发现珊瑚化石Cystophrentis kalaohoensis Yu,结合旋回地层学研究主为,在昌江县鸡心-鸡实一带南好组(C1n)中下部可能存在中晚泥盆世地层;首次发现并圈定了加里东期花岗岩体,时代为36  相似文献   

12.
沈其韩  耿元生  宋会侠 《岩石学报》2014,30(10):2777-2807
本文重点介绍我国显生宙造山带中麻粒岩的地质特征、岩石类型、P-T轨迹、变质时代及其形成的大地构造背景。我国显生宙造山带主要包括阿尔泰造山带、南天山-西南天山造山带、西昆仑造山带、东昆仑造山带、阿尔金-柴北缘造山带、北秦岭造山带、南秦岭勉略造山带、东秦岭-桐柏-大别造山带、班公湖-怒江造山带和喜马拉雅中东段造山带。这些造山带中麻粒岩的围岩有许多为蛇绿岩套或蛇绿混杂岩带,部分为副片麻岩和花岗质片麻岩,并一起经历了麻粒岩相变质改造,造山带中大多出现一种高压麻粒岩,有的与榴辉岩并存,但少数造山带中(例如阿尔泰造山带)多种压力类型麻粒岩并存,既有低-高压泥质麻粒岩、中低压基性麻粒岩、高压基性和长英质麻粒岩,又有高温-超高温泥质麻粒岩。变质时代除个别为新元古代晚期外,变质时间多为加里东、海西、印支、燕山、喜山期。麻粒岩的P-T轨迹除西天山木札尔特河低压麻粒岩具逆时针轨迹,反映大陆弧构造环境外,其它都是具有等温降压(ITC)特点的顺时针轨迹,形成的大地构造环境大部分为洋陆俯冲碰撞环境,少部分为陆-陆碰撞环境。目前显生宙造山带中麻粒岩的研究大多数尚在起步阶段,少数研究较详细,不少造山带中麻粒岩的类型和变质时代以及形成的构造背景还不清楚,有待深入研究,新的麻粒岩产地有待发现。  相似文献   

13.
刘松峰  李顺  聂鑫  邹俪琦  蔡观强 《地球科学》2021,46(11):4084-4096
为探索海南岛东南海域表层沉积物来源,揭示物源区主要地质构造演化事件,采用箱式取样法获取8个站位沉积物样品,进行锆石U-Pb定年.结果表明,773个有效年龄分布在33~3 205 Ma,主要年龄峰集中在燕山期(100 Ma、140 Ma和159 Ma)、印支期(242 Ma)和加里东期(439 Ma),次要年龄峰集中在新元古代(776 Ma、965 Ma)和古元古代(1 836 Ma、2 487 Ma),并零星保留太古宙基底年龄信息.少量变质锆石记录了加里东期和印支期强烈的变质事件.与潜在物源区对比分析表明,海南岛东南海域沉积物以约100 Ma的年龄峰值为识别标志,主要来源于海南岛.结合前人资料,本研究年龄频谱指示加里东期华夏武夷-云开造山带可延伸到海南岛,海西-印支期古特提斯洋的闭合及印支-华夏地块的碰撞导致其强烈的构造-岩浆-变质作用,燕山期受太平洋板块俯冲的影响发育多期次岩浆活动.   相似文献   

14.
Mid-Cretaceous granulite gneisses crop out in a narrow belt in the Cucamonga region of the south-eastern foothills of the San Gabriel Mountains, southern California. Interlayered mafic granulites and pelitic, carbonate, calc-silicate and quartzofeldspathic metasediments record hornblende granulite subfacies metamorphism at approximately 8 kbar and 700–800°C. Regional deformation and formation of banded gneisses ceased by c. 108 Ma. although mafic-intermediate magmatism and high-grade metamorphism continued locally as late as c. 88 Ma. Garnet zoning in metapelitic gneisses suggests that peak metamorphism was followed locally by a period of near-isobaric cooling, but this interpretation requires diachronous cooling of the granulite belt which cannot be demonstrated without detailed thermo-chronological data. It is more likely that the entire terrane remained at granulite facies P–T conditions until 88 Ma, followed by rapid uplift associated with juxtaposition against adjacent middle and upper crustal arc terranes. Uplift occurred between c. 88 and 78 Ma at rates of approximately 1–2 km Ma-1. The geotectonic evolution of the Cucamonga granulites is similar to mid-Cretaceous high- P granulites in the Sierra Nevada and Salinian block of central California. Late Cretaceous uplift common to these granulites may provide an important tectonic link between dismembered Mesozoic batholithic terranes in the California Cordillera.  相似文献   

15.
A high‐P granulite facies gneiss complex occurs in north‐west Payer Land (74°28′?74°47′N) in the central part of the East Greenland Caledonian (Ordovician–Devonian) orogen. High‐P metamorphism of the Payer Land gneiss complex resulted in formation of the assemblages Grt + Cpx + Amp + Qtz + Ru ± Pl in mafic rocks, and Grt + Ol + Cpx + Opx + Spl in rare ultramafic pods. Associated metapelites experienced anatexis in the kyanite stability field. Peak metamorphic assemblages formed around 800–850 °C at pressures of c. 1.4–1.7 GPa, corresponding to crustal depths of c. 50 km. Mafic granulites contain abundant reaction textures, including the replacement of garnet by symplectites of Opx + Spl + Pl, indicating that the high‐P event was followed by decompression while the granulites remained at elevated temperatures. Charnockitic gneisses from Payer Land show evidence of late Archean (c. 2.8–2.4 Ga) crustal growth and subsequent Palaeoproterozoic (c. 1.85 Ga) metamorphism. The gneiss complex experienced intense reworking during the Caledonian continental collision. On the basis of Caledonian monazite ages recorded from the high‐P anatectic metapelites, the clockwise P–T evolution and formation of the high‐P granulite facies assemblages is related to Caledonian crustal thickening, which resulted in formation of eclogites approximately 300 km north of Payer Land. The Payer Land granulites comprise a metamorphic core complex, which is separated from the overlying low‐grade supracrustal rocks (the Neoproterozoic Eleonore Bay Supergroup) by a late Caledonian extensional fault zone, the Payer Land Detachment. The steep, nearly isothermal, unloading P–T path recorded by the granulites can be explained by erosional and tectonic unroofing along the Payer Land Detachment.  相似文献   

16.
海南岛昌江灰色片麻岩包体及其地球化学特征   总被引:3,自引:1,他引:3  
灰色片麻岩包体出露于海南岛昌江中元古代花岗质岩石中,主要由花岗闪长质-英云间长质片麻岩及其糜棱岩组成,遭受过强烈的剪切作用和变质作用,野外产出与岩石矿物学特点及其地球化学特征均表明灰色片麻岩是正片麻岩,是以片麻岩形式存在的高Al型英云间长岩-花岗间长岩深成岩体。具有轻稀土富集型和轻稀土亏损型两种分配模式,岩石成因复杂,其Nd模式年龄为2735~2791Ma,说明海南岛存在太古宙古陆壳。||关键词##4灰色片麻岩包体;;英云间长岩-花岗间长岩;;地球化学特征;;海南昌江  相似文献   

17.
The oldest crystalline complexes of the Early Caledonian superterrane of Central Asia were formed in the Early Precambrian. They are exposed in the basement of microcontinents, which represent old cratonic fragments. Among the latters are the crystalline complexes of the Tarbagatai block previously ascribed to the Dzabkhan microcontinent. It was shown that the crystalline complexes of the Tarbagatai block have a heterogeneous structure, consisting of the Early Precambrian and later Riphean lithotectonic complexes. Structurally, the Early Precambrian complexes are made up of tectonic sheets of gneisses, migmatites, and gneiss granites of the Ider Complex that are cut by gabbroanorthosite massif. The Riphean Jargalant Complex comprises alternating hornblende crystalline schists and biotite (sometimes sillimanite-bearing) gneisses with marble horizons. The upper age boundary of the Riphean Complex is determined by the subautochthonous granitoids with age about 810 Ma. The presence of the Riphean high-grade rocks indicates that structures with newly formed crust were formed in the paleooceanic framing of the Early Precambrian blocks of the Rodinia supercontinent by the Mid-Late Riphean. Divergence that began at that time within old Rodinian cratons and caused rifting and subsequent break-up of the supercontinent was presumably changed by convergence in the paleooceanic area.  相似文献   

18.
The anorthosite complexes and related rock types of the Indian Precambrian shield are primarily associated with either cratons or mobile belts. They were metamorphosed under amphibolites to granulite facies conditions. The major rock types are chromite-bearing meta-anorthosites, amphibolites, basic granulites, pink granites and gneisses. This study was carried out on chromitite bearing samples from Sittampundi layered anorthosite complex, Tamil Nadu, to evaluate the textural and compositional relationships of rutile and chromite. The pristine composition of the chromites is still preserved inspite of intense metamorphic and tectonic process. The rutiles are differentiated into isolated, clustered and exsolved rutile grains.  相似文献   

19.
Several bodies of granulites comprising charnockite, charno-enderbite, pelitic and calc-silicate rocks occur within an assemblage of granite gneiss/granitoid, amphibolite and metasediments (henceforth described as banded gneisses) in the central part of the Aravalli Mountains, northwestern India. The combined rock assemblage was thought to constitute an Archaean basement (BGC-II) onto which the successive Proterozoic cover rocks were deposited. Recent field studies reveal the occurrence of several bodies of late-Palaeoproterozoic (1725 and 1621 Ma) granulites within the banded gneisses, which locally show evidence of migmatization at c. 1900 Ma coeval with the Aravalli Orogeny. We report single zircon ‘evaporation’ ages together with information from LA-ICP-MS U-Pb zircon datings to confirm an Archaean (2905 — ca. 2500 Ma) age for the banded gneisses hosting the granulites. The new geochronological data, therefore, suggest a polycyclic evolution for the BGC-II terrane for which the new term Sandmata Complex is proposed. The zircon ages suggest that the different rock formations in the Sandmata Complex are neither entirely Palaeoproterozoic in age, as claimed in some studies nor are they exclusively Archaean as was initially thought. Apart from distinct differences in the age of rocks, tectono-metamorphic breaks are observed in the field between the Archaean banded gneisses and the Palaeoproterozoic granulites. Collating the data on granulite ages with the known tectono-stratigraphic framework of the Aravalli Mountains, we conclude that the evolution and exhumation of granulites in the Sandmata Complex occurred during a tectono-magmatic/metamorphic event, which cannot be linked to known orogenic cycles that shaped this ancient mountain belt. We present some field and geochronologic evidence to elucidate the exhumation history and tectonic emplacement of the late Palaeoproterozoic, high P-T granulites into the Archaean banded gneisses. The granulite-facies metamorphism has been correlated with the thermal perturbation during the asymmetric opening of Delhi basins at around 1700 Ma.  相似文献   

20.
A structural, petrological and geochronological (U‐Th‐Pb of zircon and monazite) study reveals that the lower crust sequences of the Variscan high‐grade basement cropping out between Solenzara and Porto Vecchio, south‐east Corsica (France) have been tectonically juxtaposed along with middle crustal rocks during the extrusion of the orogenic root of the Variscan chain. We propose that a system of high‐temperature, orogen‐parallel shear zones that developed under a transpressive dextral tectonic regime caused the exhumation of the entire sequence. This tectonic complex is thus made up of rocks having undergone different P–T conditions (eclogite‐?, high‐pressure granulite facies and amphibolite facies) at different times, reflecting the progressive foreland migration of the orogenic front. The Solenzara granulites were derived from burial of continental crust to high‐pressure (1.8–1.4 GPa) and high‐ to ultrahigh‐temperature conditions (900–1000 °C) during the Variscan convergence: U–Pb ELA‐ICPMS zircon dating constrained the timing of this metamorphism at c. 360 Ma. The gneisses cropping out at Porto Vecchio are middle crustal‐level rocks that reached their peak temperature conditions (700–750 °C at <1.0 GPa) at c. 340 Ma. The diachronism of the metamorphic events, the foliation patterns and their geometry suggest that the granulites were exhumed to middle crustal levels through channel flow tectonics under continuous compression. The amphibolite facies gneisses of Porto Vecchio and the granulites of Solenzara were accreted through the development of a major dextral mylonitic zone forming under amphibolite facies conditions: in situ monazite isotope dating (ELA‐ICPMS) revealed that this deformation occurred at c. 320 Ma and was accompanied by the emplacement of syntectonic high‐K melts. A final HTLP static overprint, constrained at 312–308 Ma by monazite U‐Th‐Pb isotope dating, is related to the emplacement of the igneous products of the Sardinia‐Corsica batholith and marks the transition from the Variscan orogenic event to the Permian extension.  相似文献   

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