Testing and Extending the Paleomagnetic Record at Steens Mountain

测试和扩展斯蒂斯山的古地磁记录

• 批准号: 9526553
• 负责人: Robert Coe
• 金额: $ 8.03万
• 依托单位: University of California-Santa Cruz
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-02-15 至 1998-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9526553&HistoricalAwards=false
• 关键词: Testing; Extending; Paleomagnetic; Record; Steens

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.

Coe 9526553 来自Steens山玄武岩流的地磁场反转的古地磁记录为了解反转地球发电机的行为提供了有价值的见解。 然而，PI的有争议的发现大，系统的剩磁方向的变化作为一个函数的退磁温度和垂直位置内的个人流量是很好地解释了一个假设，调用短暂的插曲，在反转过程中的快速磁场变化。 然而，如果这是真的，它对地球发电机、地核和地幔有着重大的影响--地球表面的磁场变化率比目前观测到的大三个数量级，地核顶部的流体速度比目前模拟的要大得多，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学领域的核心。 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，则提供更完整和准确的描述，说明在单独流动冷却期间地磁场的方向和大小的变化。 他还计划填补并大大延长Steens Mountain记录在过渡带以下的位置，以检查异常信号，并更好地确定过渡前区域的特征。