Geomagnetic Paleointensity During Anomolous Field Behavior (Mid-Jurassic)

在太平洋侏罗纪海洋玄武岩中有一个令人兴奋的地磁场行为的发现。在400米玄武岩层序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。如此快速、连续的反转行为以前从未被观察到过。~170 Ma洋壳与0 ~ 20 Ma洋壳相似，没有明显的变化。玄武岩的磁场强度对于未改变的海洋地壳来说是正常到略高的，显微探测工作表明，这不是钛磁铁矿剩余物载体的不寻常化学反应的结果。丰富的玻璃，通常保存原始的钛磁铁矿存在于整个400米。在这种不寻常的磁场行为中，玻璃丰度提供了检查地磁场强度的机会。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，在这个间隔上地磁场强度预计是最低的。在连续变化的磁场行为和中间和零倾斜方向的记录中，玻璃丰度允许在这种不寻常的方向行为中询问地磁场的强度。将测量每个“极性”状态的古强度，以及所有存在玻璃的中间方向间隔。该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。研究结果将提供有助于约束地磁发电机理论的数据。

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.