RUI: Paleomagnetic Study of the Matuyama-Brunhes Reversal from Dated Lava Sequences on Tahiti, French Polynesia

9627927霍夫曼派建议继续他在塔希提岛熔岩中对地球最近的磁极反转--松山-布鲁内斯(M-B)的研究，并利用来自世界各地其他熔岩流动和可靠的沉积序列的现有数据集，将这一记录整合到M-B反转过程的全球模型中。随着最近对发电机过程的成功的3D计算机辅助模拟，对地磁场反转的研究正迅速发展到其复杂程度。这些进展使得从古地磁记录中了解地球表面的实际磁场行为变得至关重要。从全球4个地点熔岩获得的Matuyama-Brunnes反转数据以及最近对这些熔岩的40Ar/39Ar年龄测定支持的不是虚地磁极(VGP)沿自南向北地理轨迹迁移的单一过程，而是一个涉及一系列发电机事件和长期磁场配置的更复杂的过程。PI申请资金，以便在今后两年继续开展以下工作：(1)对记录反转的几个平行切片进行采样，(2)进一步绘制塔希提岛所经历的反转过程的综合年代图，(3)尽可能使用新改进的多标本技术对这些岩石进行古强度测定，以及(4)利用现有的沉积物数据建立松山-布鲁内斯反转过程的全球模型。本次瑞会将继续涉及加州理工学院物理专业的多名本科生。

9627927 Hoffman The PI proposes to continue his studies of the earth's most recent magnetic polarity reversal, Matuyama-Brunhes (M-B) in lavas in Tahiti, and to integrate this record into a global model of the M-B reversal process using available data sets from other lava flows and reliable sedimentary sequences worldwide. The study of geomagnetic field reversals is rapidly evolving in its degree of sophistication with recent successful 3D computer-assisted simulations of the dynamo process. These advances make essential an understanding of actual field behavior at Earth's surface obtained from the paleomagnetic record. Available data of the Matuyama-Brunhes reversal obtained from lavas from 4 sites about the globe and recent 40Ar/39Ar age determinations on these lavas support not a singular process in which the virtual geomagnetic pole (VGP) migrates along a south-to-north geographic track, but rather a more complicated process involving a series of dynamo events and long-standing field configurations. The PI requests funding to continue his effort over the next two years to (1) sample several parallel sections recording the reversal, (2) develop further a composite chronological picture of the reversal process as experienced on Tahiti, (3) perform paleointensity determinations on these rocks whenever possible using a newly-modified multispecimen technique, and (4) construct a global model for the Matuyama-Brunhes reversal process using available data from sediments. This RUI will continue to involve a number of undergraduate physics majors at California Polytechnic.