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Regional, Contact Metamorphism, and Autometamorphism of the Olkhon Terrane (West Baikal Area)
Petrology ( IF 1.5 ) Pub Date : 2020-04-02 , DOI: 10.1134/s0869591120010051 E. V. Sklyarov , A. V. Lavrenchuk , V. S. Fedorovsky , D. P. Gladkochub , T. V. Donskaya , A. B. Kotov , A. M. Mazukabzov , A. E. Starikova
Petrology ( IF 1.5 ) Pub Date : 2020-04-02 , DOI: 10.1134/s0869591120010051 E. V. Sklyarov , A. V. Lavrenchuk , V. S. Fedorovsky , D. P. Gladkochub , T. V. Donskaya , A. B. Kotov , A. M. Mazukabzov , A. E. Starikova
The rocks of the Olkhon terrane experienced high-grade regional metamorphism reaching granulite facies. In addition to regional metamorphism, they were subjected to contact metamorphism and autometamorphism (mafic dikes). Three types of regional metamorphism have been distinguished. A terrane collage north of the Orso Zone revealed two stages of regional metamorphism: early-stage granulite metamorphism (Т = 750–900°С, Р = 8–9 kbar, around 500 Ma) and late-stage amphibolite and low–amphibolite facies (Т = 550–710°С, Р = 4–6 kbar, 460–470 Ma). The Orso microterrane separating the Krestovsky island-arc subterrane from a collage of other microterranes contains high-pressure mineral assemblages (up to 10 kbar), which are characterized by the presence of high-calcium garnet in metapelites. The Orso microterrane and Krestovsky subterrane are characterized by relatively high-pressure path of metamorphism. An extended zone of contact high-temperature metamorphism related to the emplacement of gabbro of the second phase of the Ustkrestovsky Complex has been mapped in the Krestovsky subterrane. The temperature of formation of two-pyroxene hornfels after metaporphyrites of the Birkhin volcanoplutonic association is estimated at 750–850°С. Beerbachites were formed by autometamorphism of subvolcanic mafic bodies, which compose the northern part of the Tazheran composite massif (syenite, Ne-syenite, subalkaline gabbro), dikes in the Birkhin gabbro massif, as well as dikes and separate blocks in marble mélange. The temperature of autometamorphism during formation of beerbachites is estimated from two-pyroxene geothermometer as 700–1000°С.
中文翻译:
Olkhon Terrane(西贝加尔湖地区)的区域,接触变质作用和自变质作用
Olkhon地层的岩石经历了高级的区域变质作用,并达到了花岗石相。除了区域变质外,它们还经历了接触变质和自变质(铁堤)。区分了三种类型的区域变质作用。奥索地带以北的一个地层拼贴揭示了区域变质的两个阶段:早期的花岗石变质(Т = 750–900°С,Р = 8–9 kbar,约500 Ma)和晚期的闪石和低闪石相(Т = 550–710°С,Р= 4–6 kbar,460–470 Ma)。将Krestovsky岛弧地下与其他微地形拼贴分开的Orso微型地形包含高压矿物组合(最高10 kbar),其特征是在变质岩中存在高钙石榴石。Orso微型地带和Krestovsky地下的特征是变质作用的相对高压路径。与Ustkrestovsky复杂第二阶段的辉长岩的位置有关的接触高温变质作用的扩展区域已绘制在Krestovsky地下。估计Birkhin火山光成岩结合体的斑岩后形成的2 rox角horn的温度为750-850°С。Beerbachite是由亚火山岩基体的自变质形成的,它由Tazheran复合地块的北部(正长岩,Ne-正长岩,次碱性辉长岩),Birkhin辉长岩地块中的堤防以及大理石混杂岩中的堤防和单独的地块组成。根据2 geo地热仪估计,在重沸石形成过程中自变质温度为700-1000°С。
更新日期:2020-04-02
中文翻译:
Olkhon Terrane(西贝加尔湖地区)的区域,接触变质作用和自变质作用
Olkhon地层的岩石经历了高级的区域变质作用,并达到了花岗石相。除了区域变质外,它们还经历了接触变质和自变质(铁堤)。区分了三种类型的区域变质作用。奥索地带以北的一个地层拼贴揭示了区域变质的两个阶段:早期的花岗石变质(Т = 750–900°С,Р = 8–9 kbar,约500 Ma)和晚期的闪石和低闪石相(Т = 550–710°С,Р= 4–6 kbar,460–470 Ma)。将Krestovsky岛弧地下与其他微地形拼贴分开的Orso微型地形包含高压矿物组合(最高10 kbar),其特征是在变质岩中存在高钙石榴石。Orso微型地带和Krestovsky地下的特征是变质作用的相对高压路径。与Ustkrestovsky复杂第二阶段的辉长岩的位置有关的接触高温变质作用的扩展区域已绘制在Krestovsky地下。估计Birkhin火山光成岩结合体的斑岩后形成的2 rox角horn的温度为750-850°С。Beerbachite是由亚火山岩基体的自变质形成的,它由Tazheran复合地块的北部(正长岩,Ne-正长岩,次碱性辉长岩),Birkhin辉长岩地块中的堤防以及大理石混杂岩中的堤防和单独的地块组成。根据2 geo地热仪估计,在重沸石形成过程中自变质温度为700-1000°С。