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Pre-Alpine high-pressure metamorphism in the Gemer unit: mineral textures and their geodynamic implications for Variscan Orogeny in the Western Carpathians
International Journal of Earth Sciences ( IF 2.3 ) Pub Date : 2020-04-15 , DOI: 10.1007/s00531-020-01856-2
S. W. Faryad , P. Ivan , R. Jedlicka

We report mineral textures of retrogressed eclogites from the gneiss–amphibolite complex, which is represented by a series of isolated bodies that were thrusted over the greenschist-facies Rakovec group in the Gemer unit (Western Carpathians). Peak pressure and temperature conditions of about 2.0 GPa and 650 °C are estimated for the eclogite-facies assemblage (omphacite, garnet and rutile). The eclogites show strong amphibolite-facies re-equilibration that is characteristic for the rest of gneiss–amphibolite complex rocks. Pressure and temperature conditions for both eclogite and subsequent amphibolite-facies stages are comparable with those reported from the retrogressed eclogites in the Vepor and Tatra units. The underlying Rakovec group rocks indicate greenschist-facies conditions, but relicts of high-pressure (blueschist facies) metamorphism are also preserved. The Pre-Alpine age of the eclogite-facies metamorphism in the gneiss–amphibolite complex and blueschist-facies metamorphism in the Rakovec group is confirmed by the presence of their pebbles in the overlaying upper Carboniferous conglomerates. The origin of eclogites and blueschists in the Gemer unit and their relationship to eclogites in the Vepor and Tatra units are discussed with respect to the subduction zone along which they originated, but also in relation to the high-pressure rocks occurring along the European Variscan Belt. As the whole Gemer unit underwent Alpine metamorphism, the retrogressed eclogites and associated gneisses were also studied to clarify possible degree of this metamorphic overprint in the gneiss–amphibolite complex rocks.



中文翻译:

Gemer单元中的高山前高压变质作用:喀尔巴阡山脉瓦里斯坎造山作用的矿物质地及其对地球动力学的影响

我们报告了片麻岩-闪石复合物中倒榴榴岩的矿物质地,这是由一系列孤立的物体代表的,这些物体被推到盖默单元(西喀尔巴阡山脉)的绿片岩相拉科维克群上。据估计,榴辉岩相组合(方英石,石榴石和金红石)的峰值压力和温度条件约为2.0 GPa和650°C。榴辉岩显示出强的闪石-岩相重新平衡,这是片麻岩-闪石复合岩的其余部分所特有的。榴辉岩和随后的角闪岩相阶段的压力和温度条件与Vepor和Tatra单元中退化榴辉岩报道的压力和温度条件相当。下层的拉科维奇群岩石表明了绿片岩相条件,但是也保留了高压(blueschist相)变质的遗迹。通过覆盖在上部的石炭纪砾岩中的卵石的存在,证实了拉科维奇组中片麻岩-闪石复合物中的榴辉岩-岩相变质和蓝片岩-岩相变质的高山前年龄。讨论了Gemer单元中的榴辉岩和blueschist的起源以及它们与Vepor和Tatra单元中的榴辉岩的关系,涉及它们起源的俯冲带,也讨论了沿欧洲Variscan带发生的高压岩石。随着整个Gemer单元经历了高山变质作用,还研究了倒退的榴辉岩和相关的片麻岩,以弄清在片麻岩-闪石复合岩中这种变质叠印的可能程度。通过覆盖在上部的石炭纪砾岩中的卵石的存在,证实了拉科维奇组中片麻岩-闪石复合物中的榴辉岩-岩相变质和蓝片岩-岩相变质的高山前年龄。讨论了Gemer单元中的榴辉岩和blueschist的起源,以及它们与Vepor和Tatra单元中的榴辉岩的关系,涉及它们起源的俯冲带,也讨论了沿欧洲Variscan带发生的高压岩石。随着整个Gemer单元经历了高山变质作用,还研究了倒退的榴辉岩和相关的片麻岩,以弄清在片麻岩-闪石复合岩中这种变质叠印的可能程度。通过覆盖在上部的石炭纪砾岩中的卵石的存在,证实了拉科维奇组中片麻岩-闪石复合物中的榴辉岩-岩相变质和蓝片岩-岩相变质的高山前年龄。讨论了Gemer单元中的榴辉岩和blueschist的起源以及它们与Vepor和Tatra单元中的榴辉岩的关系,涉及它们起源的俯冲带,也讨论了沿欧洲Variscan带发生的高压岩石。随着整个Gemer单元经历了高山变质作用,还研究了倒退的榴辉岩和相关的片麻岩,以弄清在片麻岩-闪石复合岩中这种变质叠印的可能程度。

更新日期:2020-04-21
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