The boundary between Proterozoic and Archaean crustal blocks in central West Greenland and northern Labrador
The boundary between Proterozoic and Archaean crustal blocks in central West Greenland and northern Labrador
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格陵兰岛西部中部和拉布拉多北部元古代和太古代地壳块之间的边界
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发表时间：
1987
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影响因子：
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通讯作者：
R. Wardle
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作者：
J. Korstgård;B. Ryan;R. Wardle
早元古代Nagssugtoqidian移动的带与西格陵兰的西太平洋克拉通之间的接触，以及丘吉尔省与北方拉布拉多的西太平洋克拉通之间的接触，代表了早元古代造山边界的两个横截面。这两个地区的中生代造山带显示了元古代造山事件的边缘效应。元古宙对太古代岩脉的影响的最佳指标是晚太古代-早元古宙岩脉和不整合地覆盖在片麻岩和岩脉上的早元古宙表壳岩。格陵兰边界带的演化特征为晚白垩世（Nag. 1)横向剪切，早元古代Kangâmiut岩墙侵入和随后的（Nag. 2)韧性逆冲推覆韧性逆冲断层是Nagssugtoqidian-Eugenean边界的特征，证明了该地区地壳的大幅缩短。在拉布拉多，边界地区被划分为几个不同的区域。虽然它的演化方面类似于格陵兰的边界，但有几个根本的区别，其中最重要的是，横流运动似乎比韧性逆冲作用占主导地位。这些差异暂时有关的对比构造环境的两个地区在早元古代大陆碰撞，格陵兰岛段的正面碰撞带，而拉布拉多段文件略斜横流运动。
Summary The contact between the Early Proterozoic Nagssugtoqidian Mobile Belt and the Archaean craton in West Greenland, and that between the Churchill Province and the Archaean (Nain) craton in Northern Labrador represent two cross-sections of an Early Proterozoic orogenic boundary. The Archaean cratons in both regions display the peripheral effects of Proterozoic orogenic events. The best indicators of Proterozoic effects on the Archaean cratons are the Late Archaean-Early Proterozoic dykes and the Early Proterozoic supracrustal rocks which unconformably overlie the gneisses and dykes. In Greenland the boundary zone evolution is characterized by Late Archaean (Nag. 1) transcurrent shearing, Early Proterozoic Kangâmiut dyke intrusion and subsequent (Nag. 2) ductile overthrusting. Ductile overthrusts are characteristic of the Nagssugtoqidian-Archaean boundary and attest to substantial shortening of the crust in this region. In Labrador the boundary region has been divided into several distinct zones. Although facets of its evolution are analogous to the boundary in Greenland there are several fundamental differences, the most important of which is that transcurrent movement appears to have been dominant over ductile overthrusting. These differences are provisionally related to contrasting tectonic settings of the two areas during Early Proterozoic continental collision, the Greenland segment being the frontal collision zone whilst the Labrador segment documents slightly oblique transcurrent motion.