Geomagnetic Paleointensity During Anomolous Field Behavior (Mid-Jurassic)

莫琳B。在太平洋的侏罗纪海洋玄武岩中，人们发现了一个令人兴奋的地磁场行为。在一个400米长的玄武岩序列中观察到地磁极性的连续变化。观测到六个极性“间隔”，对应于大约每5万年一次的地磁场反转。这种快速、连续的逆转行为以前从未被观察到。~170 Ma洋壳明显未发生蚀变（类似于0-20 Ma洋壳玄武岩）。玄武岩的磁场强度是正常的略高的未蚀变的洋壳，微探针工作表明，这不是一个不寻常的化学钛磁铁矿剩磁载体的结果。在整个400米的范围内存在大量的玻璃，通常保存着原始的钛磁铁矿。玻璃丰度提供了机会，以检查地磁场强度在这一不寻常的领域行为。在不断变化的极性记录中，也存在许多中间方向的间隔，包括零倾角的间隔，预计地磁场强度将是最低的。在连续变化的磁场行为和中间和零倾斜方向的记录中的玻璃丰度允许在这种不寻常的方向行为期间询问地磁场的强度。古强度将被测量为每个“极性”状态和所有中间方向的玻璃存在的间隔。这一结果有望提供有关地磁场在如此快的时间尺度上变化的能力的信息。这些结果将为地磁发电机理论提供数据。

EAR-0126561Maureen B. SteinerAn exciting discovery of geomagnetic field behavior was made in Jurassic oceanic basalts of the Pacific Ocean. Continuous change of geomagnetic polarity was observed in a four hundred meter basalt sequence. Six polarity "intervals" were observed, corresponding to geomagnetic field reversals roughly once every 50,000 years. Such fast, continuously reversing behavior has never before been observed. The ~170 Ma oceanic crust is remarkably unaltered (similar to 0-20 Ma age oceanic basalt). Magnetic intensities of the basalt are normal to slightly high for unaltered oceanic crust, and microprobe work shows that this is not the result of an unusual chemistry of the titanomagnetite remanence carriers. An abundance of glass, which commonly preserves pristine titanomagnetite is present throughout the 400 m. The glass abundance provides the opportunity to examine geomagnetic field intensity during this unusual field behavior. In the record of constantly changing polarity, numerous intervals of intermediate directions also are present, including intervals of zero inclination at which geomagnetic field intensity would be expected to be lowest. The glass abundance in a record of continuously changing field behavior and the intermediate and zero-inclination directions allow interrogation of the intensity of the geomagnetic field during this unusual directional behavior. Paleointensities will be measured for each "polarity" state and for all intermediate-direction intervals for which glass is present. The result is expected to provide information about the geomagnetic field's ability to change on such a fast time scale. The results should provide data to help constrain geomagnetic dynamo theory.