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Chronology and Tectonic Evolution of the Southern Anti-Atlas Orogen, Morocco

摩洛哥南反阿特拉斯造山带的年代学和构造演化

基本信息

批准号：
0106853
负责人：
Scott Samson
金额：
$ 23.91万
依托单位：
Syracuse University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2001
资助国家：
美国
起止时间：
2001-06-15 至 2005-05-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=0106853&HistoricalAwards=false
关键词：
Chronology Tectonic Evolution Southern Anti

项目摘要

0106853SamsonSubstantial advances have been made in recent years in the understanding of the geological evolution of several major North American and European 'pan-African' Neoproterozoic (750-550 million year old) terranes, but there is still a fundamental gap in the knowledge of 'pan-African' orogenic belt evolution in Africa itself. Much of the uncertainty about the accretionary history of the African Neoproterozoic orogens stems from the limited database of reliable radiometric ages of structurally important units, combined with a lack of detailed modern kinematic analysis in these deformed regions. These critical data are being collected by performing combined structural, uranium-lead geochronological, and neodymium-lead-hafnium isotopic analyses of one of the pivotal Neoproterozoic African orogens, the Anti-Atlas orogen of Morocco. Through a detailed structural analysis of the deformed rocks in the region, combined with high precision uranium-lead zircon age determinations, many significant questions about the accretionary history of the southern Anti-Atlas belt are being answered. Such questions include the age and timing of obduction of ocean-floor crust (ophiolites), the relationship of these ophiolites to one another, the connections between arc-terranes to the north with ophiolites and an associated blueschist belt to the south, the age and nature of the basement of these terranes, the degree of interaction of basement with Neoproterozoic magmas, and the timing of accretion of these terranes to the West African Craton. Through modern, multi-disciplinary studies the geological 'family-tree' of the circum-Atlantic terranes with the orogens surrounding the West African Craton is being established.

近年来，对北美和欧洲几个主要的“泛非”新元古代（7.5 - 5.5亿年）地体的地质演化的认识取得了实质性进展，但对非洲本身的“泛非”造山带演化的认识仍然存在根本性的空白。非洲新元古代造山带增生史的许多不确定性源于有限的可靠的结构重要单元的辐射年龄数据库，以及对这些变形区域缺乏详细的现代运动学分析。这些关键数据是通过对一个关键的新元古代非洲造山带——摩洛哥的反阿特拉斯造山带——进行结构、铀-铅年代学和钕-铅-铪同位素分析来收集的。通过对该地区变形岩的详细构造分析，结合高精度的铀铅锆石年龄测定，回答了有关南反阿特拉斯带增生史的许多重要问题。这些问题包括海底地壳（蛇绿岩）逆冲的年龄和时间，蛇绿岩之间的相互关系，北部的弧形地体与蛇绿岩和南部的蓝片岩带之间的联系，这些地体的基底的年龄和性质，基底与新元古代岩浆的相互作用程度，以及这些地体与西非克拉通的增生时间。通过现代的多学科研究，正在建立环大西洋地体与西非克拉通周围造山带的地质“家族树”。