Testing and Extending the Paleomagnetic Record at Steens Mountain

来自Steens山玄武岩流的地磁场反转的古磁记录为研究反转地球动力的行为提供了有价值的见解。然而，PI的一个有争议的发现，即剩磁方向的大的、系统的变化是退磁温度和单个流的垂直位置的函数，这个发现可以用一个假说很好地解释，这个假说调用了反转期间惊人的快速磁场变化的短暂片段。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测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，以及下地幔的电导率非常低和/或横向不均匀。这些发现的意义是古地磁领域的核心。PI建议对他的假设进行进一步严格的测试，如果没有更好的替代方案取代，将对单个流冷却期间地磁场方向和大小的变化提供更完整和准确的描述。他还计划在过渡带以下对Steens山记录进行填充和大幅度扩展，以检查前兆信号，更好地建立过渡前场的特征。

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.