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

古地磁数据是了解地磁转变的唯一观测来源，因此也是地球发电机过程中涉及的场的产生。然而，由于反转和漂移最多发生在几千年之间，因此获取有关反转和过渡场的详细古地磁信息是一个真正的挑战。此外，由于确实需要从长火山序列中获得反转记录，以便更好地了解磁场的产生，我们建议详细研究拉奈岛的一个长火山序列(约320米)，主要目的是研究拉奈岛熔岩的定向行为(即偏角和倾角)以及在拉奈剖面记录的几次连续极性转变之前、期间和之后记录的地磁强度。我们已经在夏威夷拉奈岛上发现了一段覆盖了大约40万年的地磁场变化的火山段，其中包括研究吉尔萨、加达尔、比约恩和科布山亚时和漂移的详细记录的可能性，因为根据Ar/Ar辐射年龄测定，该段的底部年龄为1.6+/-0.08 Ma。我们还建议对拉奈熔岩序列的反转边界和预期的漂移进行额外的高精度Ar/Ar辐射测年。显然，对这些观测的正确分析需要记录总场矢量，因此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。这项为期两年的拟议研究的目标主要涉及对诸如反转和漂移等时期的场变化的了解，但也与迄今仅从少数几个相互矛盾的观测序列中记录到的反转前后的关键时间间隔有关，特别是关于1.6至~120万年之间的间隔，这一间隔仍不能很好地用上述地磁场反转和漂移来界定。反转研究不能脱离周围的极性间隔，到目前为止发表的大多数记录都不足以提供完整的信息。拉奈序列提供了第一次特殊的机会来研究包括几个极性区间的一段时间内的场变化，从而记录了各种时间常数上的古场行为。这是提取和提出重要约束条件的基本条件，对发电机的理论和数值模拟具有重要意义。首席研究员和三名本科生(S)将执行这里提出的整个科研项目。本科生的参与将是这个项目的优先事项，从田野工作到实验室工作，分析和出版。该项目将帮助支持一位代表人数较少的美国科学家(PI)。数据将通过出版物、网络和社区维护的古地磁数据库进行传播。该项目还将提供刺激，以维持UH的古地磁和岩石组构业务，该业务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.