Self-reversal in Titanomaghemite: Implications for the Magnetization of Oceanic Crust

天然回复磁化的自反转，即某些岩石获得与地球地磁场反平行方向的磁化的显著能力，被认为是罕见的;它只在少数含有血红钛铁矿的火成岩中建立。研究人员从不含铁锰铁矿的枕状玄武岩中发现了两种普遍存在的、几乎对极的磁化成分（通过详细的去磁研究揭示）。实验室热释电磁化实验表明，在较低温度下的组件分离表示部分自反转的主磁化。这种自反磁化是由低温氧化形成的钛磁赤铁矿携带的。由于大洋地壳的磁岩化作用普遍存在，部分自反转可能在控制海洋磁异常幅度随年龄变化方面发挥重要作用，研究人员建议调查深海钻探计划和大洋钻探计划回收的大洋玄武岩中钛磁赤铁矿携带的自反转程度和机制。通过对年龄从最近到170 Ma不等的地点的研究，他们希望限制获得自反转磁化的时间尺度。将应用的技术包括古地磁学、岩石磁学、X射线衍射、微探针、扫描电子显微镜和透射电子显微镜。这项工作将支持博士学位。论文和几个本科生在罗切斯特大学的研究。

TardunoEAR-0230230Self-reversal of natural remanent magnetization, the remarkable ability of some rocks to acquire a magnetization in a direction antiparallel to that of the Earth's geomagnetic field, is thought to be rare; it has been established only in a few igneous rocks bearing hemoilmenite. The investigators have have found two pervasive, nearly antipodalcomponents of magnetization (revealed through detailed demagnetization studies) from pillow basalts in which hemoilmenite is absent. Laboratory thermoremanent magnetization experiments suggest that the componentisolated at lower temperatures represents a partial self-reversal of the primary magnetization. This self-reversed magnetization is carried by titanomaghemite formed by low temperature oxidation. Because maghemitization of ocean crust is ubiquitous, partial self-reversals may play an important role in controlling changes in marine magnetic anomaly amplitudes with age.the investigators propose to investigate the extent and mechanism of self-reversal carried by titanomaghemite in oceanic basalt recovered by the Deep Sea Drilling Project and the Ocean Drilling Program. Through astudy of sites having ages ranging from recent to 170 Ma, they hope to constrain the time scales of acquisition of self-reversed magnetizations. Techniques to be applied will include paleomagnetism, rock magnetism, x-ray diffraction, microprobe, scanning electron microscopy and transmitted electron microscopy. The work proposed will support a Ph.D. thesis and the studies of several undergraduate students at theUniversity of Rochester.--