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中国蓝闪石片岩带的一般特征及其分布 总被引：28，自引：4，他引：28
蓝闪石片岩相可依据其温度划分为蓝闪石-硬柱石和蓝闪石-绿片岩相区,并与一些变质相组成不同相系。中国蓝闪石片岩带根据其平均温度-压力梯度和构造地质环境可分为:(1)元古代克拉通内蓝闪石片岩带;(2)加里东期克拉通内裂谷型蓝闪石片岩带;(3)古生代中国陆台北缘蓝闪石片岩带;(4)中新生代与俯冲作用有关的蓝闪石片岩带。蓝闪石变质作用的形成和演化与构造地质环境有关。中国蓝闪石片岩带大部分形成于硅铝壳环境,从陆壳开始裂开,直至出现洋壳。这一演化与地壳内热流变化格局有关,形成机理不属于均变论的观点。 相似文献
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在苏尼特左旗以南地区的中古生代造山带的混杂岩带内发现了以岩块形式出现的蓝片岩,其矿物组合为斜长石+阳起石+蓝闪石+绿帘石+榍石。蓝片岩化学成分说明由基性火山岩变质而成。矿物化学分析表明,蓝片岩中角闪石可分为钙质、钙钠质和钠质3类。钙质闪石均为阳起石,钙钠质闪石为蓝透闪石和冻蓝闪石,钠质闪石为蓝闪石和青铝闪石及少量镁钠闪石。利用Na(M4)和AlⅣ的含量推测本区钙质、钙钠质和钠质3类闪石的压力从0.3～0.7Gpa,表明蓝片岩相变质作用的压力约为0.7GPa。用化学反应限定蓝片岩的形成温度为200～375℃左右。40Ar39Ar同位素年代学测定蓝闪石的等时线年龄为383±13Ma(1δ)。这些结果进一步证实沿贺根山—苏尼特左旗南是一条中古生代的缝合线,其俯冲—碰撞的标志即为混杂岩带以及其中的蓝片岩。 相似文献
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中国蓝闪片岩相的变质作用 总被引：7，自引：1，他引：7
本文论述了中国蓝闪片岩的分布、变质条件及其构造位置。中国的蓝闪片岩从中晚元古代开始,各变质期均有出现。根据矿物组合,可分为两类:第一类蓝闪片岩常含有高压矿物,如硬柱石、硬玉和文石以及蓝闪石、绿纤石、黑硬绿泥石、多硅白云母、红帘石等,属高压亚绿片岩相,称蓝闪—硬柱石片岩相,形成温度约250—350℃,压力大于500—800MPa,甚至可达1200MPa。此类蓝闪—硬柱石片岩相多代表海洋板块古消减带。第二类蓝闪片岩的常见矿物为蓝闪石、青铝闪石或镁钠闪石、黑硬绿泥石、红帘石和绿片岩相中的绿帘石、阳起石、绿泥石、白云母、有时还有黑云母、铁铝榴石和钠质辉石。形成温度约350—450℃,压力500—800MPa。此类蓝闪绿片岩相虽处于活动带,但与板块构造没有直接关系。我国西藏南部和内蒙温都尔庙属第一类,但大部分蓝闪片岩带属第二类。 相似文献
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北阿尔金高压/低温(HP/LT)变质岩呈构造岩片分布在俯冲-增生杂岩中，主要由强变形的变质沉积岩(泥质片岩、钙质片岩和石英片岩)和少量呈透镜状分布在变沉积岩中的蓝片岩和榴辉岩组成，与相邻的蛇绿混杂岩呈断层接触。榴辉岩主要矿物为绿辉石、石榴子石、多硅白云母、石英、冻蓝闪石，含少量蓝闪石、绿泥石、方解石、钠长石、榍石。蓝片岩主要矿物为蓝闪石、石榴子石、碳酸盐类矿物、阳起石、绿帘石、钠云母、绿泥石、钠长石和石英，偶见多硅白云母，其中在部分蓝片岩的石榴子石中有少量硬柱石和绿辉石包体。本文对蓝片岩(样品A06-16-7)和榴辉岩(样品A03-3-5.3)开展了岩石学和相平衡模拟研究，得到它们形成的压力峰期的温压条件分别是：T=～524℃、P=～2.1GPa和T=～527℃、P=～2.2GPa,并均经历了后期蓝片岩相的退变质叠加。结合区域上已有的研究表明，北阿尔金HP/LT混杂岩片中不同类型岩石可能经历了不同的变质演化历史，反映了古俯冲隧道的不均匀性，并在俯冲隧道的较浅部混杂在一起，共同经历了蓝片岩相或蓝片岩-绿片岩过渡相条件下的透入性变形作用。 相似文献
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在苏北连云港地区(红石咀、东西连岛及蟹脐沟)发现以岩块、岩片形式出现的蓝闪绿片岩相岩石，其由石榴石、蓝透闪石、冻蓝闪石、阳起石、钠长石、多硅白云母、榍石及文石等矿物组成。石榴石变斑晶作为低扩散的刚性矿物，经历了多期变质变形作用，变质反应证据保存在石榴石的成分环带及包体矿物组合中。蓝透闪石、冻蓝闪石及文石包体的存在表明，本区出露的绿片岩相岩系属早期经历低温高压变质作用、晚期又叠加绿片岩相变质作用的高压变质地体。这一发现为苏鲁高压地体的构造单元划分提供了重要依据。 相似文献
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牡丹江地区蓝片岩中脉状青铝内石^40Ar—^39Ar年龄及其地质意义 总被引：5，自引：0，他引：5
对穆棱县的磨刀石、椅子圈地区的蓝片岩研究，确定其经受过三期叠加变质作用：第一期为蓝片岩相变质作用：第二期为蓝闪绿片岩相变质作用；第三期为受断裂构造控制的动力变质作用，形成脉状青铝闪石、钠长石等变质矿物。通过对脉状产出的青铝闪石＾４０Ａｒ－＾３９Ａｒ年龄测定，获得较好的年龄谱，坪年龄为１５４．７±０．７Ｍａ。此年龄表明了该期变质作用与敦－密断裂发生大规模左行走滑有关，由于大型走滑断裂造成局部构造超高 相似文献
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黑龙江依兰地区蓝片岩的变质演化P-T-t轨迹 总被引：3，自引：3，他引：0
黑龙江省依兰地区出露了一套经高压变质形成的蓝片岩、云母片岩、长英质糜棱岩和少量超基性岩及大理岩并经历了强变形作用改造,一直被认为是佳木斯地块与其西侧松嫩地块碰撞拼贴所形成的缝合带产物。本次研究,通过岩相学与矿物化学分析,根据矿物组合的不同,识别出研究区内三种不同类型的蓝片岩;并获得了绿帘蓝闪石片岩(T=350~550℃,P=10~14kbar)、蓝闪霓辉石片岩(T=350~550℃,P=10~14kbar)和石榴石冻蓝闪石片岩(T=500~540℃,P=10~12kbar)的峰期变质温压条件。结合前人发表的地质年代学数据,建立了变质演化P-T-t轨迹。其中,绿帘蓝闪石片岩具"发卡式"变质演化P-T-t轨迹;而蓝闪霓辉石片岩与石榴石冻蓝闪石片岩具顺时针的演化轨迹。我们推测其成因可能为不同类型的蓝片岩形成于不同的俯冲阶段,由动力学机制的变化所造成。该研究成果为进一步探索佳木斯地块与松嫩地块碰撞拼贴的构造演化过程提供重要的依据。 相似文献
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High pressure-low temperature metamorphism in the Gran Paradiso basement, Western Alps 总被引：1，自引：0，他引：1
J. R. VEARNCOMBE 《Journal of Metamorphic Geology》1983,1(2):103-115
The Gran Paradiso basement complex of the French and Italian Alps is composed of metasediments, termed the gneiss minuti, and metabasic rocks, both of which are intruded by a late Hercynian granite. The Bonneval gneiss, which crops out at the western edge of the complex, is composed of highly deformed metasediments, volcanics and volcaniclastic rocks. Eclogites, now highly altered, occur in the metabasic rocks. Kyanite and blue-green amphibole are locally present in the gneiss minuti and aegirine plus riebeckite occur in the Bonneval gneiss. A moderately high pressure - low temperature metamorphic event of probable Alpine age occurred in the basement complex. This metamorphic event differs from that in the overlying Sesia unit and ophiolites of the Schistes lustrés nappe in being at lower pressures (below the ab = jd100 + qz transition) and post-dating the major (D2A ) deformation. The origin of the metamorphism is discussed and interpreted as a probable consequence of the overlying nappe pile which was emplaced during the D2A event. Subsequent greenschist facies metamorphism in the basement complex is a consequence of thermal relaxation during uplift. 相似文献
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The metamorphic history of mafic exotic blocks from a tectonic melange zone within an allochthonous ophiolitic terrane (Marmora Terrane) of the Pan-African Gariep orogenic belt in south-western Namibia was studied, based on mineral parageneses and amphibole composition. Glaucophane described previously from these rocks could not be verified. Instead, two types of blue amphiboles were distinguished: (i) rims of (ferro-) edenitic to pargasitic to barroisitic hornblende composition around brownish amphibole phenocrysts replacing magmatic clinopyroxene, and (ii) deep blue porphyroblasts of magnesio-riebeckite with little ferro-glaucophane component in a highly metasomatized albite-rich rock. Textural and mineralogical evidence, particularly the existence of up to three different amphibole generations in metagabbro samples, supports a multiphase metamorphic history experienced by these exotic blocks. The first metamorphic event, M1, is interpreted as very low- P hydrothermal oceanic metamorphism that affected the igneous protoliths at up to amphibolite facies temperatures. Subsequent M2 metamorphism was syntectonic and is characterized by temperatures similar to those attained during M1 but higher pressures indicating burial to 15–20 km. This event is related to a subduction process. The third metamorphic event, M3, was low grade and of regional nature. It is the only one recorded in the sedimentary envelope of the exotic blocks. The formation of magnesio-riebeckite is considered a retrograde reaction at greenschist facies during M2. The results indicate that in the Gariep belt subduction and subsequent obduction have occurred, although blueschist facies metamorphism has not been reached. 相似文献
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内蒙古头道桥地区出露了一套经高压变质形成的岩石组合。本次研究通过岩相学和矿物化学分析,根据矿物组合的不同,识别出蓝片岩、绿片岩两种不同类型的岩石类型。其中,蓝片岩的矿物组合为角闪石（蓝闪石、蓝透闪石）+绿帘石+钠长石+绿泥石+石英+赤铁矿±多硅白云母±方解石±榍石;绿片岩的矿物组合为绿泥石+钠长石+石英±绿帘石±角闪石（阳起石、镁角闪石、蓝透闪石、冻蓝闪石等）±多硅白云母±赤铁矿。确定了蓝片岩的峰期变质级别为绿帘-蓝闪片岩相,峰期变质温度为400~600℃,压力为1.2~1.4 GPa。绿片岩的峰期变质级别为绿帘-角闪岩相。结合前人研究成果,认为蓝片岩和绿片岩的形成与额尔古纳地块和兴安地块的碰撞拼合有关。 相似文献
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中条山早元古代变质岩石的PTt轨迹和构造演化 总被引：2，自引：0，他引：2
中条山早元古代变质岩石呈北东向分布，经历了中低级变质作用。本文在变质作用研究的基础上，结合地质构造和显微构造，利用近来发展的石榴石环带定量测量Ｐ－Ｔ轨迹的技术，建立了绛县群和中条群泥质岩石经历的ＰＴｔ轨迹。ＰＴｔ轨迹表明绛县群经历拉张作用，地壳发生抬升，产生绿片岩相变质；在中条第Ⅰ期运动中，地壳略有增厚或不变升温和抬升，产生低角闪岩相变质；而中条群岩石经历低绿片岩相埋深变质后，于中条第Ⅰ期运动中， 相似文献
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Fabio Zulbati 《Geological Journal》2011,46(1):82-103
Metabasites from the northern Adula Nappe Complex (ANC) display a complex microstructural evolution recording episodes of deformation and metamorphic re‐equilibration that were obliterated in the surrounding phengite‐bearing schists. Pre‐D1 and D1 deformation episodes are preserved as mineral inclusions within garnet cores of some amphibole‐bearing eclogites and record high‐temperature greenschist‐/amphibolite‐facies conditions. D2 produced an eclogite‐facies foliation which developed at 580 ± 70°C and 19 ± 3 kbar. D3 was a composite deformation episode which can be divided into three sub‐episodes D3m, D3a and D3b which occurred as the metamorphism evolved from post‐eclogitic high‐pressure and low‐temperature conditions through to amphibolite‐facies conditions at 590 ± 30°C and 11.7 ± 1.3 kbar. The D3 deformation episode was responsible for the development of the S3 regional‐scale foliation in the surrounding schists, whilst D4 caused the development of an S4 greenschist foliation. The composite nature of the D3 episode indicates that rocks of the northern ANC experienced a protracted post‐eclogitic structural reworking and that the current structure of this part of the Alps is a late‐Alpine feature. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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Sushina nepheline syenite gneisses of Early Proterozoic North Singhbhum Mobile Belt (NSMB), eastern India suffered regional metamorphism under greenschist-amphibolite transitional facies condition. The Agpaitic Sushina nepheline syenite gneisses consist of albite, K-feldspar, nepheline (close to Morozewicz-Buerger composition), aegirine, biotite, epidote, piemontite, sodalite, cancrinite, natrolite and local alkali amphibole. Accessory phases include zircon, hematite, magnetite, rare pyrochlore and occasional eudialyte and manganoan calcic zirconosilicates. Mineral chemistry of albite, K-feldspar, nepheline, aegirine, alkali amphibole, natrolite and zirconium silicate minerals are described. The detailed textural features together with chemical data of some minerals indicate metamorphic overprint of these rocks. A new reaction is given for the genesis of metamorphic epidote. Metamorphic piemontite suggests greenschist facies metamorphism under high fO2 (Hematite-Magnetite buffer). Up to 15.34 mol% of jadeite component in aegirine suggests that the metamorphic grade of the nepheline syenite gneiss reached at least to greenschist-amphibolite transitional facies or higher. Nepheline geothermometry suggests temperature of metamorphism <500 °C, which is consistent with greenschist facies metamorphism of surrounding chlorite-biotite-garnet phyllite country rock. 相似文献
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胶北蓬莱群的变形与变质及其区域大地构造意义 总被引：6，自引：0，他引：6
朱光 《大地构造与成矿学》1993,17(3):259-270
本文通过构造与变质研究及伊利石结晶度和同位素年龄测定。分析胶北蓬莱群的变形,变质及其区域大地构造意义。作为胶北唯一盖层的蓬莱群,在晚石炭世(299±4Ma)北北东—南南西区域挤压下首次遭受了强烈的蓬莱事件变形及低绿片岩相变质。其后的后蓬莱事件在胶北地区仅造成了局部的北北东—南南西向变形构造。作为华北板块南缘的胶北带,其上的蓬莱事件是华北与扬子板块沿胶南带碰撞的结果。这表明郯庐断裂带以东这两扳块碰撞发生在晚石炭世。在秦岭—大别山碰撞带以北的华北扳块南缘,由于碰撞也出现了类似胶北带的挤压变形。 相似文献
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内蒙古色尔腾山地区花岗绿岩带糜棱岩变形变质过程探讨 总被引：2，自引：0，他引：2
采用不同研究方法分析和解读岩石和矿物的显微构造特征，能再造结晶基底岩石复杂的变形和变质演化过程和条件。通过对色尔腾山地区花岗绿岩带中韧性剪切带的糜棱岩显微构造、石英组构、矿物化学等综合分析，发现该区糜棱岩在经历了低角闪岩相区域变质及绿帘角闪岩相退变质变形之后，发生了不均匀进变质重结晶作用及中低绿片岩相退变质变形等几个演化阶段。由不同阶段温压条件所限定的p-T演化轨迹为一个在早期顺时针的基础上叠加了一个晚期逆时针环的复杂图像。 相似文献
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《Journal of Asian Earth Sciences》2007,29(4-6):385-408
The Dadeldhura thrust sheet inm western Nepal consists of Proterozoic–Lower Paleozoic sedimentary and plutonic rocks, and their metamorphic equivalents, that rest structurally on Proterozoic strata of the Lesser Himalayan sequence. Although regional metamorphism and ductile deformation were widespread during Tertiary thrust emplacement, relicts of early Paleozoic tectonism are preserved locally. New field and geochronologic studies, together with the findings of previous workers, indicate that this early Paleozoic tectonism included: (1) regional metamorphism to at least garnet grade, (2) regional folding of a thick metamorphic sequence into a broad east–west trending syncline, (3) outcrop-scale folding of metasedimentary rocks, (4) emplacement of Cambro–Ordovician granitic bodies during and after the metamorphism and deformation, (5) uplift and erosion of the metamorphic sequence, with garnet-grade rocks locally exposed at the surface, and (6) derivation of Ordovician conglomeratic sandstones from the early Paleozoic orogen. Similar records of metamorphism, deformation, and uplift/erosion have been found in other regions of the Himalaya, indicating that rocks of the Dadeldhura thrust sheet were originally involved in a regionally extensive orogenic system. Future tectonic models of Himalayan orogenesis must accommodate this early Paleozoic event. 相似文献
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本文对中国早前寒武纪太古期、早元古期、中晚元古期的变质作用的分布、岩石类型、变质相特点、变质相划分及同位素年龄数据等进行了论述。将中国前寒武纪地壳划分为华北、西北、华南、西南四个变质区、各变质区有自己的不同特点和演化历史。前寒武纪地壳演化是陆壳增长的历史,区域高温和中温变质作用是太古代原始地壳特有的变质作用。 相似文献