Acquisition of a Sensitive Magnetic Susceptibility System and a Reflected Light Microscope for Studies of Self-Reversal in Titanomaghemite

一些岩石具有与地球地磁场方向相反的磁化能力，或自然剩余磁化的自我逆转，这种非凡的能力被认为是罕见的；它只在少数含血红铁矿的火成岩中得到证实。罗彻斯特的古磁学实验室通过详细的热消磁研究揭示了两种几乎对映的磁化成分，这些成分来自不含铁铁矿的枕状玄武岩。实验室部分热磁化的应用表明，在较低温度下分离的元件代表了一次磁化的部分自反转。由于海洋地壳岩浆化现象普遍存在，部分自反转可能是近3000万年形成的地壳中海洋磁异常振幅随年龄减小的重要原因。这笔拨款将用于购置两套设备系统，以协助进一步研究海洋玄武岩中钛磁铁矿的自反转程度和机制：(1)磁化率系统，配有炉具，用于居里点测定；(2)反射光显微镜系统，用于基本表征磁相。该设备将支持一篇博士论文和几名本科生的论文研究。该设备还将支持其他研究生、本科生和博士后研究人员在地磁、构造学、岩石磁学和环境磁学方面的持续工作，以及罗切斯特大学的正式课程指导

0236383TardunoThe remarkable ability of some rocks to acquire a magnetization in a direction antiparallel to the Earth's geomagnetic field, or self-reversal of natural remanent magnetization, is thought to be rare; it has been established only in a few igneous rocks bearing hemoilmenite. The paleomagnetism lab at Rochester has reported on two, nearly antipodal components of magnetization, revealed through detailed thermal demagnetization studies, from pillow basalts in which hemoilmenite is absent. Application of laboratory partial thermoremanent magnetizations have shown that the component isolated at lower temperatures represents a partial self-reversal of the primary magnetization. Because maghemitization of oceanic crust is ubiquitous, partial self-reversals may make an important contribution to the decrease in marine magnetic anomaly amplitudes with age observed for crust formed during the last 30 million years.Funds from this grant will be used to acquire two equipment systems to assist in further investigations of the extent and mechanism of self-reversal carried by titanomaghemite in oceanic basalt: (1) a magnetic susceptibility system with a furnace apparatus for Curie point determinations and (2) a reflected light microscope system for basic characterization of magnetic phases. The equipment will support a Ph.D. thesis and the thesis studies of several undergraduate students. The equipment will also support the continuing work of other graduate students, undergraduates and postdoctoral researchers conducting studies in geomagnetism, tectonics, rock magnetism and environmental magnetism, and in formal course instruction at the University of Rochester.***