Collaborative Research: Paleomagnetic Investigation of Quaternary Volcanics from Kenya and the Galapagos Islands: In Search of the Time-Averaged Magnetic Equator

合作研究：肯尼亚和加拉帕戈斯群岛第四纪火山岩的古地磁调查：寻找时间平均磁赤道

• 批准号: 0608998
• 负责人: Neil Opdyke
• 金额: --
• 依托单位: University of Florida
• 依托单位国家: 美国
• 项目类别: Continuing grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-07-01 至 2010-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0608998&HistoricalAwards=false
• 关键词: Collaborative; Research; Paleomagnetic; Investigation; Quaternary

The study seeks to obtain high-quality paleomagnetic data from normal and reverse polarity lava flows of Pleistocene age (0-1.7 Ma) from Kenya to constrain the time-averaged field at the equator and to determine the Time-Averaged Magnetic Equator. A previous study on equatorial lavas from Ecuador (Opdyke et al., G-cubed, in revision) leads to the hypothesis that the magnetic field at the equator is best modeled with a ~5% axial quadrupole contribution to the geocentric axial dipole field. This model predicts that the geomagnetic field at a latitude of approximately 3 deg. north will be horizontal and represent the position of the Time-Averaged Magnetic Equator whereas at the geographical equator it will be inclined about 4 deg. These differences are small but detectable with the large data sets that we hope to obtain from lavas at the equator in the vicinity of Mt Kenya and about 3 deg. north of the equator in the area around Loyangalani on the east shore of Lake Turkana, where a large volcano, Mt. Kulal, lies just to the east and there are also voluminous lava flows in the Gregory rift on the southern shore of Lake Turkana that can be sampled. Sampling will be done over two years in two sampling trips each of about a month's duration. The time-averaged geomagnetic field is expected to be symmetrical around the Earth's spin axis and this study will test that hypothesis since the region of the proposed study is 135 deg. east from Ecuador. Data will also obtained and processed from samples from 80 sites collected from the Galapagos Islands. Preliminary results for this sample collection were reported by Rochette et al. (1997) and the unused portions of the drill cores will be fully demagnetized. Thellier paleointensity studies will be done on selected samples from both the Kenya and the Galapagos collections in an attempt to obtain a full vector characterization of the paleofield. Therefore, at the conclusion of this study, high-quality paleomagnetic data will be available from three large studies of lavas from near the equator (Equador, Kenya and Galapagos Islands) and these data will greatly increase the knowledge of the configuration of the time-averaged geomagnetic field. Among the broader impacts of this work are training of graduates and undergraduates.

该研究旨在从肯尼亚更新世年龄（0-1.7 Ma）的正极性和反极性熔岩流中获得高质量的古地磁数据，以限制赤道的时间平均场并确定时间平均磁赤道。以前对厄瓜多尔赤道熔岩的研究（Opdyke等人，G-cubed，in revision）导致假设赤道处的磁场最好用对地心轴向偶极场的~5%轴向四极贡献来建模。该模型预测纬度约3度的地磁场。北是水平的，代表时间平均磁赤道的位置，而在地理赤道上，它将倾斜约4度。这些差异很小，但可检测到的大型数据集，我们希望从熔岩在赤道附近的肯尼亚山和约3度。赤道以北，图尔卡纳湖东海岸的洛扬加拉尼周围地区，那里有一座大火山，Kulal就位于东部，在图尔卡纳湖南部海岸的格雷戈里裂谷也有大量的熔岩流可以取样。取样将在两年期间分两次进行，每次约一个月。时间平均的地磁场预计是对称的地球自转轴，这项研究将测试这一假设，因为该地区的拟议研究是135度。东从厄瓜多尔。还将从从加拉帕戈斯群岛80个地点收集的样本中获得数据并进行处理。Rochette等人（1997年）报告了这次样品采集的初步结果，未使用的岩心部分将被完全消磁。Thellier paleointensity研究将在肯尼亚和加拉帕戈斯采集的选定样品上进行，以获得古磁场的完整矢量特征。因此，在这项研究结束时，将从赤道附近（厄瓜多尔、肯尼亚和加拉帕戈斯群岛）的三项大型熔岩研究中获得高质量的古地磁数据，这些数据将大大增加对时间平均地磁场结构的了解。 这项工作的更广泛影响包括对毕业生和本科生的培训。