Cretaceous Intensity of Earth's Magnetic Field from Thellier Analyses of Single Plagioclase Crystals

了解地球磁场过去的强度对于理解地球发电机至关重要。不幸的是，由于实验的改变，准确和精确的数据是有限的。研究人员开发了一种新的方法，使用从镁铁质岩石中分离出来的斜长石晶体。他们已经表明，这些晶体含有微小的磁性夹杂物（尺寸为50-250 nm），不易受蚀变的影响。在这项工作中，研究人员将（一）通过岩石磁性和高分辨率扫描透射电子显微镜，加深对斜长石中基本岩石磁性载体的了解;（ii.）约束磁场的性质，在一个时间时，地磁反转频率是在最低限度（白垩纪正常极性超时）使用Thellier paleointensity分析斜长石晶体分离的镁铁质岩石形成在低纬度网站和（iii）。通过对在高反转频率时期形成的熔岩中的斜长石晶体的Thellier分析，进一步检验反转频率和强度的一般关系。重要的是，将研究根据全岩玄武岩和海底玄武岩玻璃分析得出的具有高技术质量的现有古强度结果的地点，从而有机会比较来自不同地质记录仪的结果。这项研究的更广泛影响包括支持一名研究科学家和一名研究生（后者有助于获得博士学位）。论文研究）。此外，调查人员将涉及几个本科生的工作，有助于本科研究和本科高级论文研究在罗切斯特大学。

TardunoEAR-0309968Knowing the past intensity of Earth's magnetic field is essential for understanding the geodynamo. Unfortunately, accurate and precise data are limited because of experimental alteration. The investigators have developed a new approach that uses plagioclase crystals separated from mafic rocks. They have shown that these crystals contain minute magnetic inclusions (50-250 nm in size) that are less susceptible to alteration. In this work, the investigators will (i.) gain an increased understanding of the basic rock magnetic carriers in plagioclase through rock magnetism and high resolution scanning transmission electron microscopy; (ii.) constrain the nature of the field during a time when geomagnetic reversal frequency was at a minimum (the Cretaceous Normal Polarity Superchron) using Thellier paleointensity analyses of plagioclase crystals separated from mafic rocks formed at low latitude sites and (iii.) test further the general relationship of reversal frequency and intensity by Thellier analyses of plagioclase crystals from lavas formed during a time of high reversal frequency. Importantly, sites with existing paleointensity results of high technical quality based on analyses of whole rock basalt and submarine basaltic glass will be studied, affording the opportunity to compare results derived from different geologic recorders. Broader impacts of the study include support for a Research Scientist and a graduate student (the latter contributing to Ph.D. thesis studies). In addition, the investigators will involve several undergraduate students in the work, contributing toward undergraduate research and undergraduate Senior thesis studies at the University of Rochester.