Magnetostratigraphy and Polarity transitions studies of lavas of the island of Lanai, Hawaii

古地磁资料是了解地磁转变的唯一观测资料来源，从而了解磁场产生中涉及的地球动力学过程。然而，由于地磁倒转和偏移最多只发生在几千年的时间里，因此获取有关地磁倒转和过渡磁场的详细古地磁信息是一项真正的挑战。另外，由于为了更好地了解该场的生成，需要从长火山层序中获得反转记录，我们建议进行详细的研究。拉奈岛的一个长火山层序（约320米）熔岩，主要目的是研究方向行为（即赤纬和倾角）以及拉奈岛剖面记录的几次连续极性转变前后记录的地磁场强度。我们已经在拉奈岛（夏威夷）确定了一个火山剖面，覆盖了大约40万年的地磁场变化，包括研究连续的吉尔萨、加尔达、比约恩和科布山亚时纪和旅行的详细记录的可能性，因为该剖面的底部是1.6 +/-0.08 Ma，根据Ar/Ar辐射年龄测定。我们还建议对拉奈熔岩层序的反转边界和预期偏移进行高精度的Ar/Ar辐射定年。显然，对这些观测结果进行适当的分析需要记录总场矢量，因此，本文建议对拉奈火山熔岩流序列所记录的古场的方向变化和绝对古强度进行详尽的研究。这项为期两年的研究计划的目标主要与了解反转和偏移等时期的磁场变化有关，但也与反转前后的关键时间间隔有关，到目前为止，这些时间间隔仅从少数沉积序列中记录下来，观察结果相互矛盾。特别是在160万年到120万年之间，这个时间间隔仍然不能很好地用上述地磁场的反转和偏移来定义。反转研究不能与周围的极性间隔分开，迄今为止发表的大多数记录都不够长，无法提供完整的信息。拉奈层序提供了第一个特殊的机会来研究一个时间段内的磁场变化，包括几个极性间隔，从而记录了不同时间常数下的古磁场行为。这是提取并提出地球动力学理论和数值模拟的重要约束条件。主要研究员和三名本科生将完成这里提出的整个科研项目。在这个项目中，本科生的参与将是一个优先事项，从实地考察到实验室工作，分析和出版。该项目将帮助支持一位来自代表性不足的少数民族（PI）的美国科学家。数据将通过出版物、网络和社区维持的古地磁数据库传播。该项目还将为维持休斯敦大学的古地磁和岩石结构操作提供刺激，这些操作由来自世界各地的不同学生和研究人员使用。

Paleomagnetic data are the unique source of observations to understand the geomagnetic transitions and hence the geodynamo processes involved in field generation. However, because reversals and excursions occur over a few thousands years at most, it is a real challenge to acquire detailed paleomagnetic information about the reversing and the transitional field. In addition, due to the fact that there is a real need to obtain reversal records from long volcanic sequences in order to have a better understanding of the generation of the field, we propose to study in detail, a long volcanic sequence (about 320 meters) of lavas from the island of Lanai with the main objective of investigating the directional behavior (i.e. Declination and Inclination) as well as the geomagnetic field strength recorded before during and after several successive polarity transitions registered by the Lanai section. We have already identified a volcanic section on the island of Lanai (Hawaii) covering about 400,000 years of geomagnetic field changes that includes the possibility of studying the detailed records of the successive Gilsa, Gardar, Bjorn and Cobb Mountain Subchron and excursions, since the base of the section is 1.6 +/-0.08 Ma old according to Ar/Ar radiometric age determinations. We also propose to do additional high precision Ar/Ar radiometric dating of the reversal boundaries and the expected excursions of the Lanai lava sequences. It is clear that proper analysis of these observations requires documenting the total field vector and therefore conducting an exhaustive study of the directional changes and absolute paleointensity of the paleo-field recorded by the sequence of lava flows of the Lanai Volcano is proposed here. The objectives of this two year proposed study are primarily related to the knowledge of the field variations during periods like reversals and excursions but also related to the critical time intervals that precede and follow reversals that so far have only been documented from a few sedimentary sequences with conflicting observations, particularly for the interval between 1.6 to ~1.2 Million years that is still not very well defined in terms of the above mentioned reversals and excursions of the geomagnetic field. Reversal studies cannot be separated from the surrounding polarity intervals and most records published so far were not long enough to provide complete information. The Lanai sequence offers the first exceptional opportunity to study field changes over a time period that includes several polarity intervals and thus documents the paleofield behavior over various time constants. This is a basic condition to extract and bring up significant constraints for the theoretical and numerical modeling of the geodynamo. The principal investigator and three undergraduate student(s) will carry out the entire scientific research project proposed here. The involvement of undergraduate students will be a priority in this project, from fieldwork through lab work, analysis and publication. The project will help support a US scientist of an underrepresented ethnic group (the PI). Data will be disseminated through publication the web and community maintained paleomagnetic databases. This project will also provide the stimulus to maintain the paleomagnetics and petrofabrics operation at UH which is used by a diverse group of students and researchers from all over the world.