Testing and Extending the Paleomagnetic Record at Steens Mountain

CoE 9526553斯蒂恩斯山脉玄武岩流动的地磁场逆转的古地磁记录为地球发电机的逆转行为提供了有价值的见解。然而，PI有争议地发现了剩磁方向作为退磁温度和单个流动中垂直位置的函数的大的、系统的变化，这一发现被一个假说很好地解释得很好，该假说在反转过程中调用了令人惊讶的快速场变化的短暂事件。然而，如果这是真的，它将对地球发电机、地核和地幔产生重大影响--地球表面的磁场变化率比目前观察到的要大三个数量级，地核顶部的流体速度比目前模拟的要大得多，并且下地幔的导电率非常低和/或横向上不均匀。这些发现的意义是古地磁学领域的核心。PI建议对他的假设进行更严格的测试，如果没有更好的替代方案，则提供更完整和准确的描述，说明在个别气流冷却期间地球磁场的方向和大小的变化。他还计划在过渡地带下方填写并大大扩展斯蒂恩斯山记录，以便检查前兆信号，并更好地确定过渡前区域的特征。

Coe 9526553 The paleomagnetic record of a geomagnetic field reversal from Steens Mountain basalt flows has provided valuable insights into the behavior of the reversing geodynamo. However, the PI's controversial discovery of large, systematic variation of remanence direction as a function of demagnetization temperature and vertical position within individual flows is explained quite well by a hypothesis that invokes brief episodes of astonishingly rapid field change during the reversal. If true, however, it has significant implications for the geodynamo, the core, and mantle--rates of change of field at the earth's surface three orders of magnitude larger than currently observed, fluid velocities at the top of the core much larger than currently modeled, and very low and/or laterally inhomogeneous electrical conductivity of the lower mantle. The implications of these findings are central to the field of paleomagnetics. The PI proposes to undertake further stringent tests of his hypothesis, and, if it is not supplanted by a better alternative, to provide a more complete and accurate description of the changes in direction and magnitude of the geomagnetic field during cooling of the individual flows. He also plans to fill in and greatly extend the Steens Mountain record below the transition zone in order to check for precursory signals and to better establish the character of the pre-transitional field.