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Accretion and crustal evolution of continental margin terranes in the Appalachians of Eastern Canada: aprocess-oriented study

加拿大东部阿巴拉契亚山脉大陆边缘地体的增生和地壳演化：面向过程的研究

基本信息

批准号：
162246962
负责人：
Professor Dr. Hans-Joachim Massonne
金额：
--
依托单位：
Geological Survey of Canada
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2010
资助国家：
德国
起止时间：
2009-12-31 至 2017-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/162246962?language=en
关键词：
Accretion crustal evolution continental margin

项目摘要

We further concentrate on low-grade, low- to medium-pressure metamorphic rocks of predominantly mafic and felsic composition within collision zones of microplates along the eastern margin of Laurentia. The continuous accretion of these microplates mainly contributed to the growth of the North American continent during the early Palaeozoic. Our successful integrated and process-oriented approach using petrological and geochronological methods can now be finished within a considerably shortened prolongation period, because in the first period our methods were tested in detail, a huge data base was largely provided and worked out, and all our geochemical themes published. With the existing data base our main goal, to test tectonic models with petrological and geochronological data can be finished. Hence following existing models along three very different collison zones of microplates can substantially be modified and/or refined: (1) weak crustal thickening and dispersion of the colliding microplate succeeded the collision of the Avalonia terrane during the Devonian in northeastern Newfoundland; (2) along the Iapetus suture in central Newfoundland involving soft collision without high pressure metamorphism it can be demonstrated that predominant deformation, crustal thickening and metamorphism occurred substantial time after collision with decreasing intensity and due to large distance effects of further collisions; (3) along a complex collision zone along the Baie Vert Line in western Newfoundland which represents a hard collision with high pressure rocks in the lower plate, unusual late deformation with moderate crustal thickening in the upper plate can be observed and a transition of low-grade high pressure rocks from the lower to the upper plate.

我们进一步关注劳伦大陆东缘微板块碰撞带内主要由镁铁质和长英质组成的低品位、低至中压变质岩。这些微板块的不断增生主要促进了早古生代北美大陆的生长。我们使用岩石学和地质年代学方法成功的集成和面向过程的方法现在可以在相当短的延长期内完成，因为在第一阶段我们的方法经过了详细测试，很大程度上提供和制定了巨大的数据库，并且发布了我们所有的地球化学主题。利用现有的数据库，我们的主要目标是可以完成用岩石学和地质年代学数据测试构造模型。因此，沿着三个非常不同的微板块碰撞区的现有模型可以进行实质性修改和/或细化：（1）碰撞微板块的弱地壳增厚和分散继承了纽芬兰东北部泥盆纪期间阿瓦隆尼亚地体的碰撞； (2) 沿着纽芬兰中部的土卫八缝合线，涉及软碰撞，但没有高压变质作用，可以证明，主要变形、地壳增厚和变质作用在碰撞后很长时间内发生，且强度逐渐减弱，并且由于进一步碰撞的距离效应较大； (3)沿着纽芬兰西部Baie Vert线的复杂碰撞带，代表与下板块高压岩石的硬碰撞，可以观察到上板块不寻常的晚期变形和中度地壳增厚，以及低品位高压岩石从下板块到上板块的过渡。