俄罗斯白海活动带中的太古宙榴辉岩 |
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引用本文: | 李小犁,张立飞,魏春景.俄罗斯白海活动带中的太古宙榴辉岩[J].地学前缘,2013,20(2). |
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作者姓名: | 李小犁 张立飞 魏春景 |
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作者单位: | 北京大学地球与空间科学学院;造山带与地壳演化教育部重点实验室,北京100871 |
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摘 要: | 在俄罗斯白海活动区发现的迄今为止最古老的太古宙榴辉岩的出露,对整个地质学领域是一次革命性事件。白海活动带位于芬诺斯干地亚地盾东北部太古宙陆核,处于科拉半岛大陆和卡累利阿克拉通之间的太古宙增生碰撞带中,在新太古代和古元古代期间多次受到中高压变质和构造变形作用。榴辉岩出露包括Gridino和Salma两大地区。Gridino榴辉岩区的榴辉岩产状可分为TTG片麻岩围岩中具有复杂成因的太古宙榴辉岩包裹镶体(2.72Ga),组成强烈构造变形的混合混杂岩体(mélange),以及众多古元古代侵入岩墙岩脉状基性榴辉岩。Salma榴辉岩区的榴辉岩年龄应该晚于2.87Ga,其中的Fe-Ti-榴辉岩年龄测定为约2.80Ga。两大榴辉岩区的p-T演化轨迹比较类似,Gridino榴辉岩的峰期变质温压值(T=740~865℃,p=1.4~1.8GPa)比Salma榴辉岩(T≈700℃,p=1.3~1.4GPa)要高。Salma榴辉岩原岩可能与大洋环境有关。
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关 键 词: | 白海活动带 太古宙榴辉岩 Gridino榴辉岩 Salma榴辉岩 |
Archean eclogites from Belomorian Mobile Belt, Russia |
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Abstract: | The oldest eclogite outcrops with Archean age were found in Belomorian Mobile Belt in Russia,which is a sharp breakthrough in geology.The Belomorian Mobile Belt is located at the north-east of Archean nucleus of the Fennoscandian shield,in the Belomorian accretionary-collisional orogeny between Kola Peninsula and Karelian craton,which was affected many times by high-moderate-pressure metamorphism and structural deformation in Neoarchean and Paleoproterozoic periods.There are two eclogite-bearing areas,Gridino and Salma.Gidino eclogites include polygenetic Archean eclogite fragments(~2.72 Ga) with complicated composition,consisting of migmatized and strongly deformed tectonic mélange,and various Paleoproterozoic mafic dykes and veins.Salma eclogites were considered to be formed at 2.87 Ga,and the Fe-Ti-eclogite variety at 2.8 Ga.The two eclogite assemblages have similar p-T evolution paths in general,and the p-T condition of Gridino eclogite(T=740—865 ℃,p=1.4—1.8 GPa) should be higher than that of Salma eclogites(T≈700 ℃,p=1.3—1.4 GPa).The protolith of Salma eclogite might be related with oceanic environment. |
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Keywords: | Belomorian mobile belt Archean eclogite Gridino eclogite Salma eclogite |
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