Electron Microscopy and Rock Magnetism of Ocean Floor Basalts with Implications for Paleo-Intensity Measurements

[804765] Van der Voo提出了一种岩石磁性和电子显微镜研究方法，利用会聚束电子衍射对在近代和侏罗纪之间年龄变化的海底玄武岩中的铁钛氧化物进行研究，以确定所观察到的海洋磁异常强度变化的原因，并检查其对古强度研究的影响。以前，人们认为较老的海底玄武岩的磁场强度降低是由于岩浆化造成的，但最近的观察对这一机制提出了质疑。如果能够证明，在较老的玄武岩中，细粒的钛磁铁矿并不总是被氧化，那么它很可能是关于古代地磁强度的信息来源。由于海底玄武岩在150 Ma以后大量存在，未氧化的钛磁铁矿可能成为测定古强度的一种很有前途的工具

9804765 Van der Voo A rock magnetic and electron microscope investigation, using convergent beam electron diffraction, is proposed for iron titanium oxides in ocean-floor basalts that vary between Recent and Jurassic in age, to determine the causes of the observed changes in intensity of marine magnetic anomalies and to examine their implications for paleo-intensity studies. Previously, the reduced magnetic intensity of older ocean-floor basalts was thought to be due to maghemitization, but recent observations have raised questions about this mechanism. If it can be shown that fine-grained titanomagnetite has not always been oxidized in older basalts, then it may well be a source of information about ancient geomagnetic intensities. Because ocean-floor basalts are abundant for times since 150 Ma, unoxidized titanomagnetites could become a promising tool for paleo intensity determinations.=20