RUI: Paleomagnetic Study of Transitional Fields Recorded Throughout the Cenozoic by Australasian Lavas

RUI：澳大利亚熔岩在整个新生代记录的过渡场的古地磁研究

• 批准号: 0230347
• 负责人: Kenneth Hoffman
• 金额: $ 31万
• 依托单位: California Polytechnic State University Foundation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-12-01 至 2007-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0230347&HistoricalAwards=false
• 关键词: RUI; Paleomagnetic; Study; Transitional; Fields

Hoffman0230347The most remarkable feature of Earth's magnetic field is its ability to reverse polarity, and much of our knowledge of this phenomenon has come from the paleomagnetic record found in rocks. The goal of this project is to locate, sample and analyze transitional field behavior recorded in Australasia by hotspot-erupted lavas that comprise the Great Dividing Range of Eastern Australia and New Zealand's South Island volcanoes. These volcanics are known to span the past 70 Ma, that is, the entire Cenozoic period, and thus offer an unprecedented opportunity to investigate aspects of Earth's reversing geodynamo from a single regional site over considerable geologic time. In particular, the investigators plan to test the claim that an inordinate number of transitional virtual geomagnetic poles (VGPs) associated with several available paleomagnetic reversal records are found near Australia. This observation has prompted an intriguing possibility, namely, that a concentration of magnetic flux emanating from Earth's fluid outer core below Australasia has largely dominated the field structure during many past reversals, and further, that this flux feature is a consequence of long-standing physical conditions of the lowermost mantle. Because the volcanics of Australia and New Zealand are almost directly above the claimed flux concentration, the project is designed to test this hypothesis. It is anticipated that results from this project will shed light on whether the lower mantle has had such a pronounced effect on the transitioning field over much, or all, of the Cenozoic period, and if so, whether any observable variation, or drift, of the flux feature has occurred since the end of the Mesozoic. In addition, an attempt will be made to determine both paleointensity over this span of time as well as precise radiometric ages of the lava sections. The project will be assisted by undergraduate physics majors working on their senior projects (a mandatory requirement for graduation at Cal Poly State University), exposing them to many aspects of original basic research. Dr Gary Acton of Texas A& M University and Professor Brad Singer of the University of Wisconsin will collaborate on this research.--

霍夫曼0230347地球磁场最显著的特征是它能够反转极性，我们对这一现象的许多知识都来自于在岩石中发现的古地磁记录。 该项目的目标是定位，采样和分析在澳大利亚记录的热点喷发熔岩，包括东澳大利亚和新西兰的南岛火山的大分水岭的过渡领域的行为。 已知这些火山岩跨越过去70 Ma，即整个新生代，因此提供了一个前所未有的机会，可以从一个单一的区域站点在相当长的地质时间内调查地球的逆转地球发电机的各个方面。 特别是，研究人员计划测试澳大利亚附近发现的与几个可用的古地磁反转记录相关的过渡虚拟地磁极（VGP）数量过多的说法。 这一观测结果引发了一个有趣的可能性，即，从地球的流体外核以下澳大拉西亚的磁通量集中在很大程度上主导了过去的许多逆转期间的场结构，并进一步，这种通量功能是长期存在的最低地幔的物理条件的结果。 由于澳大利亚和新西兰的火山岩几乎直接高于声称的通量浓度，因此该项目旨在验证这一假设。 预计该项目的结果将揭示下地幔是否在新生代的大部分或全部时间内对过渡场产生如此明显的影响，如果是这样，自中生代结束以来是否发生了任何可观察到的通量特征的变化或漂移。 此外，还将尝试确定这段时间内的古强度以及熔岩部分的精确放射性年龄。 该项目将由从事高级项目的本科物理专业的学生协助（这是加州理工州立大学毕业的强制要求），使他们接触到原始基础研究的许多方面。 德克萨斯农工大学的加里阿克顿博士和威斯康星州大学的布拉德辛格教授将合作进行这项研究。