Browsing by Author "Doctor, RK"

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    First constraint on historical geomagnetic secular variation in Cambodia, Southeast Asia
    (American Geophysical Union (AGU), 2018-12-13) Doctor, RK; Cai, S; Tauxe, L; Hendrickson, M; Hua, Q
    The geomagnetic field is a consequential component of the Earth, most importantly acting as a deflector of harmful solar radiation. Studying variations over the past thousands of years allows reconstructed field models to be used as a tool for archaeological dating, and helping to constrain the structure of the Earth’s interior. In current geomagnetic field models, Southeast Asia has little empirical historic data; therefore, archaeomagnetic data from Cambodia, an area currently devoid of data, can be used to refine the models. The purpose of this study is to examine the viability of using ancient furnaces to determine the secular variation of the geomagnetic field in Cambodia. Our samples are taken from ancient furnaces used for smelting iron, from the Khmer Empire near Tonle Bak, Cambodia. Via radiocarbon techniques, these furnaces have been dated between the 12th to 13th century. Twenty-six oriented samples were collected from three furnaces. These samples can be analyzed using paleomagnetic methods to measure the magnetic remanence vector and reconstruct the ancient magnetic field. Using a step-wise thermal demagnetization method, the direction of the field during the cooling of the furnaces was determined. Based on preliminary results (~20), samples from the furnaces are good recorders of the ancient magnetic field, resulting in excellent demagnetization behavior. Additionally, paleointensity experiments on the same samples will be conducted and should result in scalar values of intensity. Together, this study will give the full vector information of the geomagnetic field around 12th to 13th century in Cambodia, which can be used to recreate the geomagnetic secular variation in this area. © AGU 2018