Palaeoproterozoic structural evolution of polyphase migmatites in Olkiluoto, SW Finland

IF 1.3 4区地球科学 Q2 GEOLOGY

Bulletin of the Geological Society of Finland Pub Date : 2022-12-27 DOI:10.17741/bgsf/94.2.002

Jon Engström, A. Kärki, S. Paulamäki, I. Mänttäri

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引用次数: 1

Abstract

In migmatitic environments the behaviour of the system is controlled by the generation and amount of the anatectic melt. Accordingly, migmatites typically show a genetic linkage between the tectonic deformation and melt migration. We investigated this relationship in Olkiluoto (SW Finland) and identified four phases of ductile deformation, which are distinguished by the multiple folding phases, ductile shear events and cross-cutting features associated with pegmatitic leucosomes and/or a specific type of diatexitic migmatite with feldspar megacrysts. U–Pb LA-MC-ICPMS data on zircon cores and rims from migmatites and cross-cutting pegmatites indicate two distinct metamorphic events associated with melt generation and migration at 1.87–1.84 Ga and 1.82–1.78 Ga. These two migmatitic events suggest that the orogenic evolution of the area was long-lasting and characterized by slow cooling. The structural data and the age constraints presented in this paper support the idea of similar tectonic evolution and metamorphic environment in SW Finland and central E Sweden.

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芬兰西南部Olkiluoto地区古元古代多相杂岩的构造演化

在混染岩环境中，系统的行为受消熔熔体的产生和数量的控制。因此，混合岩在构造变形和熔体迁移之间具有典型的成因联系。我们研究了Olkiluoto(芬兰西南部)的这种关系，并确定了四个韧性变形阶段，这些阶段以多个褶皱阶段、韧性剪切事件和与伟晶质白色小体和/或具有长石巨晶的特定类型的闪长质混辉岩相关的交叉切割特征为特征。混合岩和横切辉晶岩的锆石芯和边缘的U-Pb LA-MC-ICPMS数据表明，在1.87 ~ 1.84 Ga和1.82 ~ 1.78 Ga，两个不同的变质事件与熔体的产生和迁移有关。这两次混染事件表明该地区的造山演化是长期的，具有缓慢降温的特征。本文的构造资料和年龄约束支持芬兰西南部和瑞典中部具有相似的构造演化和变质环境的观点。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Bulletin of the Geological Society of Finland GEOLOGY-

CiteScore

1.30

自引率

0.00%

发文量

审稿时长

>12 weeks

期刊介绍： Bulletin of the Geological Society of Finland (BGSF) publishes research articles and short communications in all branches of geosciences. Contributions from outside Finland are welcome, provided that they contain material relevant to Finnish geology or are of general interest.