Full Vector Studies of Polarity Transitions and Excursions Recorded in Long Sequences in the Koolau Volcano, O'ahu, Hawai'i.

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，因此获取有关反转磁场的详细古地磁信息是一个真正的挑战。和过渡性领域。确实需要从长的火山序列中获得反转记录，以便更好地了解油田的生成。因此，本文建议研究6个厚度从300~800米不等的长火山序列，它们记录了库劳火山(O‘ahu，Hawaii)记录的几次古磁场连续反转和漂移，覆盖了约0.7 Ma的地磁场变化。其中包括Gauss-Matuyama(2.57 Ma)、Cryptochron C2r.2r-L(约2.42-2.44 Ma)、留尼汪岛(S)、哈克贝利(2.137-2.086 Ma)和下奥杜瓦(1.922 Ma)的连续反转的详细记录。这项为期三年的拟议研究的目标主要涉及对逆转和漂移等时期的场变化的了解，但也涉及逆转前后的关键时间间隔，特别是2.6Ma至1.8年Ma之间的间隔，这一间隔在留尼汪岛(S)和新近报道的哈克贝利岭事件方面仍未得到很好的定义。反转研究不能脱离周围的极性区间，到目前为止发表的大多数记录都不足以提供完整的信息。这些序列提供了第一次特殊的机会来记录包括几个极性间隔的时间段内的场变化，从而记录了各种时间常数上的场行为。这是提取和提出对地球发电机的理论和数值模拟的重要约束的基本条件。拟议活动的智力优点：本提议侧重于定向分析和古强度研究，以实现总场矢量的确定。如上所述，测量将集中在极性的连续周期及其相关的反转上。使用一种改进的Thellier-Coe技术对来自几个Koolau流的每个熔岩流的一个样本进行了古强度的初步实验。我们已经制定了一个严格的标准来丢弃受磁矿学转换影响的样品以及涉及多域颗粒的磁化成分。事实上，重要的是要处理依赖于每一次熔岩流至少五到八次测定的古强度值(方向就是这种情况)，以便用适当的误差棒进行适当的统计处理。首席调查员和4名本科生将执行这里提出的研究项目。本科生的参与将是这个项目的优先事项，从实地工作到实验室工作，分析和出版。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，以维持休斯顿大学的古地磁学和岩石组构业务，该业务由不同的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 reversal and excursions occur over a few thousand years at most, it is a real challenge to acquire detailed paleomagnetic information about the reversing field. and the transitional field. There is a real need to obtain reversal records from long volcanic sequences to have a better understanding of the generation of the field. Therefore it is proposed here to study six long volcanic sequences varying in thickness from 300 to 800 meters that have registered several successive reversals and excursions of the paleofield recorded in the Koolau Volcano (O'ahu, Hawaii) covering about 0.7 Ma of geomagnetic field changes. These include detailed records of the successive Gauss-Matuyama (2.57 Ma), Cryptochron C2r.2r-l (ca. 2.42-2.44 Ma), Reunion(s), Huckleberry (2.137-2.086Ma) and Lower Olduvai (1.922 Ma) reversals. The objectives of this three year proposed study are primarily related to the knowledge of the field variations during periods like reversals and excursions but are also related to the critical time intervals that precede and follow reversals, particularly for the interval between 2.6 to 1.8 Ma years that is still not very well defined in terms of the Reunion(s) and the newly reported Huckleberry Ridge events. Reversal studies cannot be separated from the surrounding polarity intervals, and most records published so far were not long enough to provide complete information. These sequences offer the first exceptional opportunity to document field changes over a time period that includes several polarity intervals, thus documenting the field behavior over various time constants. This is a basic condition to extract and bring up significant constraints for theoretical and numerical modeling of the geodynamo.Intellectual merit of the proposed activity: The present proposal is focused on directional analyses and paleointensity studies in order to achieve determinations of the total field vector. The measurements will focus on the successive periods of polarity and their associated reversals as mentioned above. Preliminary experiments of paleointensity have been conducted on one sample per lava flow from several Koolau flows using a modified version of the Thellier-Coe technique. We have imposed a severe criteria to discard samples affected by magnetomineralogical transformations as well as magnetization components involving multidomain grains. Indeed it is important to deal with paleointensity values that rely on a minimum number of five to eight determinations per lava flow (as is the case for directions) in order to perform a suitable statistical treatment with appropriate error bars.Broader impacts of the proposed activity. The principal investigator and 4 undergraduate students will carry out the research project proposed here. The involvement of undergraduate students will be a priority in this project, from field work through lab work, analysis and publication. Data will be disseminated through publications, the web and community maintained paleomagnetic databases. This project will also provide stimulus to maintain the paleomagnetics and petrofabrics operation at UH which is used by a diverse group of students and researchers.--