US-Mexico Cooperative Research: Geomagnetic Paleointensity Determinations on Historic Lava Flows

该奖项将支持明尼苏达大学的Horst Worm教授和Subir Banerjee教授与墨西哥国立自治大学（UNAM）的Jaime urrutia - fuugauchi教授合作。研究人员打算研究历史熔岩流中的磁记录，并将其与磁观测数据进行比较。墨西哥非常适合这一目的，因为它的活跃火山历史提供了许多具有不同成分和冷却历史的历史熔岩流。同样重要的是，自1791年以来就有了对地磁场的直接测量。拟议的研究将分为两个阶段。首先，系统地研究了不同特征的熔岩流在垂直和水平剖面上的剩磁变化。此外，还将确定磁性能和矿石岩石学特征。第一阶段的研究结果将为系统的古强度方法研究提供良好的基础。热法和非热法将评估其适用性、准确性和效率。自然剩余磁化（NRM）将在UNAM的古地磁实验室进行研究，而磁滞、各向异性和其他测量以及详细的强度测定将在明尼苏达大学进行。此外，显微探针和扫描电子显微镜的工作将由德国的Negendank教授参与，从而为该项目增加了一个多边的维度。这项提议的工作将是研究古强度记录的第一阶段，一直追溯到二叠纪时期，那时墨西哥几乎保留了一个独特的连续火山记录。

This award will support Professor Horst Worm and Professor Subir Banerjee of the University of Minnesota in collaboration with Prof. Jaime Urrutia-Fucugauchi of the Universidad Nacional Autonoma de Mexico (UNAM). The researchers intend to study the magnetic record in historic lava flows and to compare it with magnetic observatory data. Mexico is uniquely suited for this purpose because its active volcanic history has supplied numerous historic lava flows of varying composition and cooling history. Equally important, direct deter- minations of the geomagnetic field are available since 1791. The proposed research will consist of two phases. First, the variation of magnetic remanences in lava flows of different charac- teristics will be systematically studied in vertical and horizontal profiles. Additionally, magnetic properties and ore petrological characteristics will be determined. Results from the first phase of the study will provide an excellent basis for systematic paleointensity method studies. Thermal and non- thermal methods will be evaluated for their applicability, accuracy, and efficiency. Natural remanent magnetizations (NRM's) will be studied in the paleomagnetic laboratory at UNAM while magnetic hysteresis, anisotropy and other measurements as well as detailed intensity determinations will be performed at the University of Minnesota. In addition microprobe and scanning electron microscope work will involve Prof. Negendank in Germany, thus adding a multi- lateral dimension to this project. The proposed work will be the first stage in studying the paleointensity record all the way back to Permian times since when Mexico has retained an almost unique continuous volcanic record.