Collaborative Research: Creating Earth’s earliest continents—an integrated investigation of the growth and modification of western Australia’s Pilbara Craton

合作研究：创造地球最早的大陆——对澳大利亚西部皮尔巴拉克拉通的生长和改造进行综合调查

基本信息

批准号：
2020057
负责人：
Basil Tikoff
金额：
$ 29.99万
依托单位：
University of Wisconsin-Madison
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2020
资助国家：
美国
起止时间：
2020-08-01 至 2024-07-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=2020057&HistoricalAwards=false
关键词：
Collaborative Research Creating Earth earliest

项目摘要

The formation of Earth’s earliest continents is topic of significant interest in the Earth Sciences. A major issue is that rocks preserved from Earth’s earliest history are rare; there are few rocks from the first billion years of Earth’s history, and no intact rocks at all remaining from the first 500 million years. Geologists must use a very fragmental record to determine when first continental crust formed, what was it composition, and how much of it existed. This grant will support geologists to study the Earth’s oldest, unmodified fragment of a tectonic plate – the Pilbara terrane of West Australia – to address these issues. The approach is to first determine the age of the rocks through the formation of minerals, such as zircons, that act a radioactive clocks (geochronology). Once the age is known, the chemistry of the rocks can determine if they were derived from an earlier crust or extracted directly from the Earth’s mantle (geochemistry). The patterns and fabrics of these rocks (structural geology), when integrated with geochemistry and geochronology, will determine how and when the rocks were added to the crust to create these early continents. The major outcome of this work will be a better understanding of the history of the Earth’s earliest crust and the processes that formed it. The work includes student training, mentorship and support for a junior scientist (post-doctoral fellow), and international collaboration. Additionally, work with a cognitive scientist will help students envision geological processes over large time scales. The proposal will allow technique development of sophisticated geochemical and geochronologic analyses and their use in the WSU isotope laboratory by national and international visitors.This proposal seeks to address the fundamental processes of crustal formation, modification, and stabilization by examining granitic complexes—the Mt Edgar and Corunna Downs—and associated surpracrustal rocks of the 3.5 – 2.8 Ga East Pilbara terrane of West Australia, through an integrated geochronological, geochemical, and structural study. The East Pilbara terrane is one of the best-preserved examples of Paleo- to Mesoarchean crust on Earth, displaying the classic dome-and-keel pattern in which granitic complexes (domes) are surrounded by steeply dipping volcanic and volcaniclastic supracrustal lithostratigraphy (keels). Two central, interlinking questions guide our research: 1) What were the mechanisms and timing of emplacement of the granitic complexes; and 2) What were the mantle and crustal source regions for the rocks of the East Pilbara terrane. To investigate these questions, our work will focus on: 1) The geochemistry and structure of the compositionally and deformationally heterogeneous granitic dome complexes; 2) The timing, metamorphic conditions, and structure in the deformed regions of the supracrustal lithostratigraphy (“greenstone keels”); and 3) The geochemistry of the metavolcanic rocks in the supracrustal lithostratigraphy and the grantic domes, in regions of minimal deformation, to address the mantle and crustal source regions. This integrated geochemical and structural approach will provide information on first-order tectonic processes that resulted in the formation, modification, and stabilization of one of Earth’s earliest cratons and, therefore, provide important insights into the formation and preservation on some of the earliest continental crust on Earth.This project is supported by both the Petrology & Geochemistry and Tectonics programs.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.

地球最早的大洲的形成是地球科学引起了重大兴趣的话题。一个主要问题是，从地球最早的历史中保存的岩石很少见。从地球历史的前十亿年开始，很少有岩石，而且从头5亿年开始，几乎没有完整的岩石。地质学家必须使用非常碎片的记录来确定何时形成第一次大陆壳，它的组成以及其中的数量。该赠款将支持地质学家研究地球最古老的，未修改的构造板块 - 西澳大利亚州的皮尔巴拉地座，以解决这些问题。该方法是首先通过矿物的形成（例如锆石）来确定岩石的年龄，该矿物的作用是放射性时钟（地质学）。一旦知道了年龄，岩石的化学反应就可以确定它们是源自较早的地壳还是直接从地球地幔（地球化学）中提取。这些岩石的模式和织物（结构地质）与地球化学和年代学集成在一起时，将决定如何以及何时将岩石添加到地壳中以创建这些早期大陆。这项工作的主要结果将更好地理解地球最早地壳的历史以及形成它的过程。这项工作包括针对初级科学家（博士后研究员）和国际合作的学生培训，指导和支持。此外，与认知科学家合作将帮助学生设想在大时尺度上的地质过程。 The proposal will allow technical development of sophisticated geochemical and geochronological analyses and their use in the WSU isotope laboratory by national and international visitors.This proposal seeks to address the fundamental processes of crustal formation, modification, and stabilization by examining granitic complexes—the Mt Edgar and Corunna Downs—and associated surfacrustal rocks of the 3.5 – 2.8 Ga East Pilbara terrane of West澳大利亚通过综合的地质学，地球化学和结构研究。东比尔巴拉地座是地球上最保存完好的古代甲壳的最保存完好的例子之一，展示了经典的圆顶和冰川图案，其中花岗岩络合物（圆顶）被蒸蒸日上的火山和火山碎裂的上层上层岩性岩石植物（Keels）所包围。两个中心的相互联系的问题指导我们的研究：1）花岗岩复合物的增强的机制和时间是什么？ 2）什么是东比尔巴拉地层岩石的地幔和地壳来源。为了研究这些问题，我们的工作将重点放在：1）综合和变形异质的花岗岩圆顶络合物的地球化学和结构； 2）在岩性岩性地层学的变形区域（“ Greenstone Keels”）的变形区域中的时间，变质条件和结构； 3）在最小变形区域中，岩性岩石地层学和良好的域中的Metavolcanic岩石的地球化学，以解决地幔和地壳源区域。 This integrated geochemical and structural approach will provide information on first-order tectonic processes that resulted in the formation, modification, and stabilization of one of Earth’s earliest cratons and, therefore, Provide important insights into the formation and preparation on some of the earliest continental crust on Earth.This project is supported by both the Petrology & Geochemistry and Tectonics programs.This award reflects NSF's statutory mission and has been使用基金会的智力优点和更广泛的影响标准，认为通过评估被认为是宝贵的支持。