Is there a Pangean suture zone in southeastern New England?

新英格兰东南部是否存在盘古缝合带？

基本信息

批准号：
1827429
负责人：
Yvette Kuiper
金额：
$ 19.71万
依托单位：
Colorado School of Mines
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2018
资助国家：
美国
起止时间：
2018-08-15 至 2022-07-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1827429&HistoricalAwards=false
关键词：
there Pangean suture zone southeastern

项目摘要

Ever since Tuzo Wilson asked whether the Atlantic Ocean closed and then reopened in a famous 1966 paper in the journal Nature, this idea has been generally accepted and explored. It is well established that ~180 million years ago the Atlantic Ocean opened along approximately the same line as where the continents around the pre-Atlantic Ocean had closed and formed supercontinent Pangea by ~250 million years ago. This supercontinent included the Americas to the west and Eurasia (Europe and Asia) and Africa to the east of the Pangean suture zone. It is possible, however, that some continental fragments were transferred from Eurasia/Africa to the Americas and/or vice versa, if the Atlantic Ocean opened anywhere along a line that did not follow the suture zone. To date, this has not been demonstrated. The eastern New England Appalachians consist of a collage of microcontinents that collided with and became part of North America between ~470 and ~360 million years ago, before the formation of Pangea. One of the last of these arriving microcontinents, the Avalon terrane, is interpreted to constitute southeastern Massachusetts, Rhode Island, and southeastern Connecticut. Recently, the principal investigator and coauthors of a 2017 paper published in the journal Geology discovered a fragment of West African (Moroccan) crust in offshore Massachusetts that was stranded during the breakup of Pangea. Careful review of existing data for what has been interpreted as the Avalon terrane of southeastern New England suggests that part of it may in fact be part of this West African fragment. The purpose of the proposed work is to test this hypothesis. If true, southeastern New England will be the first known location where the major Pangean suture zone is exposed on land. It may become the first location where geologists and geophysicists who work in the Appalachians, West Africa and beyond can come together and study the main suture zone that formed the most recent supercontinent. Bedrock geologic maps and our understanding of the geology of Massachusetts, Rhode Island, Connecticut and the northern Appalachians may change significantly.The idea that part of what is generally accepted to be the southeastern New England Avalon terrane may actually be a west African fragment that remained after the breakup of Pangea has not previously been explored, because Avalonian and west African rocks have similar characteristics and ages. However, the ages of zircon in sedimentary and granitic rocks distinguishes them. For example, Avalonian rocks have a strong affinity with approximately one billion year old crust, and West African rocks with approximately two billion year old crust. Therefore, one billion year old zircon is common in Avalonian sedimentary rocks, where they were deposited as grains of sediment, and in Avalonian granitic rocks, where they were incorporated in the granitic melt as it penetrated the crust. The same is true for two billion year old zircon in West African rocks. At the latitude of Boston and to the north, existing data are indicative of the Avalon terrane. To the south, existing data are sparse and can be interpreted either way. The purpose of the proposed work is to analyze the ages of zircon grains in sedimentary and granitic rocks from the area south of the latitude of Boston to understand their origins and affinities. Where no bedrock is exposed, samples from existing drill core will be used.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

自从图佐·威尔逊（Tuzo Wilson）问大西洋是否关闭，然后在《大自然》杂志上的著名论文中重新开放，这一想法已被普遍接受和探索。众所周知，约有1.8亿年前，大西洋沿着大西洋周围的大洲关闭并在约2.5亿年前结束并形成了超大陆的潘吉亚。这个超大型大陆包括西方和欧亚大陆（欧洲和亚洲）和非洲的美洲。但是，如果大西洋沿没有沿缝合区的线路开放，那么有可能将一些大陆碎片从欧亚/非洲转移到美洲，反之亦然，反之亦然。迄今为止，尚未证明这一点。新英格兰东部的阿巴拉契亚族人由小核心的拼贴画，与北美相撞并成为470至3.6亿年前的北美的一部分。这些到达的微型植物中的最后一个是阿瓦隆地形，被解释为构成马萨诸塞州东南部，罗德岛州和康涅狄格州东南部。最近，在《地质》杂志上发表的2017年论文的主要研究者和合着者发现了马萨诸塞州近海的西非（摩洛哥）地壳的片段，该碎片被困在Pangea分手期间。仔细审查现有数据，以解释为新英格兰东南部的阿瓦隆地形，这表明其中一部分实际上可能是该西非碎片的一部分。拟议工作的目的是检验这一假设。如果是的话，新英格兰东南部将是第一个已知的Pangean缝合区域在陆地上暴露的地方。它可能成为第一个在阿巴拉契亚人，西非及以后工作的地质学家和地球物理学家可以聚集在一起，研究构成最新超大陆的主要缝合区。基岩地质地图以及我们对马萨诸塞州，罗德岛，康涅狄格州和阿巴拉契亚省北部的地质学的理解可能会发生很大的变化。这种观念的观点可能实际上是新英格兰东南部的新英格兰阿瓦隆地形，实际上可能是西非碎片，这可能是一个以前没有探索过的帕吉亚人，因为Avalan and Agrany and Agran and Agran and Agran and Agran and Agran and Agran and Agran and Agran and Agran and Agran and Agran and Agran and Agran and Agran and Agran and Agran and Agran and Agran and Agran and Agran。但是，沉积物和花岗岩岩石中锆石的年龄使它们区分开来。例如，阿瓦隆（Avalonian）的岩石具有大约十亿年的地壳的强烈亲和力，西非岩石的岩石约有20亿年的地壳。因此，十亿年历史的锆石在阿瓦隆沉积岩中很常见，在那里它们被沉积为沉积物颗粒，在阿瓦隆的花岗岩岩石中，在渗透地壳时，它们被掺入花岗岩融化中。西非岩石中有20亿年历史的锆石也是如此。在波士顿和北部的纬度上，现有数据表明了阿瓦隆地座。在南部，现有数据稀疏，可以用任何一种方式来解释。拟议工作的目的是分析来自波士顿纬度南部地区的沉积和花岗岩岩石中锆石颗粒的年龄，以了解其起源和亲和力。如果未暴露基岩，将使用现有钻芯的样本。该奖项反映了NSF的法定任务，并使用基金会的知识分子优点和更广泛的影响审查标准，被认为值得通过评估来获得支持。