BROAD TRENDS IN GEOMAGNETIC PALEOINTENSITY ON HAWAII DURING HOLOCENE TIME
BROAD TRENDS IN GEOMAGNETIC PALEOINTENSITY ON HAWAII DURING HOLOCENE TIME
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DOI：
10.1029/93jb00024
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发表时间：
1993-05-10
影响因子：
3.9
通讯作者：
CHAMPION, DE
中科院分区：
文献类型：
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作者：
MANKINEN, EA;CHAMPION, DE
用Thelliers方法测定了夏威夷岛上22个玄武岩熔岩流的古强度。放射性碳测年表明，这些流动爆发的间隔约为200至1000年，实验结果提供了估计的广泛趋势，在全新世时期在夏威夷附近的地磁古强度。大多数样品是从快速冷却的流动边缘，因此，通常包含两个钛磁铁矿人口。只有两个分析的79个样本未能产生的古磁场的估计，表明古强度可以从这样的样品，如果仔细选择。虚拟的偶极矩计算的流量进行了比较，使用世界各地的古地磁数据构建的偶极场强度的公布曲线。大nondipole领域，以前假设的夏威夷附近得到证实，目前的数据表明，他们是目前从约5000年B. P.，也许是最近的过去200年。然而，这些数据表明，这些非偶极子源在距今12000 ~ 5000年之间实际上是不存在的。
Paleointensity determinations have been obtained from 22 basaltic lava flows on the island of Hawaii using the Thelliers' method. Radiocarbon dating indicates that these flows erupted at intervals ranging from about 200 to 1000 years, and results of the experiments provide an estimate of broad trends in geomagnetic paleointensity during Holocene time in the vicinity of Hawaii. Most of the samples were obtained from quickly cooled flow margins and, as a consequence, typically contain two titanomagnetite populations. Only two of the 79 samples analyzed failed to yield an estimate of the paleofield, demonstrating that paleointensities can be obtained from such samples if carefully selected. Virtual dipole moments calculated for the flows are compared with a published curve of dipole field intensity that was constructed using worldwide archeomagnetic data. The large nondipole fields that were previously postulated for the vicinity of Hawaii are confirmed, and the present data indicate that they were present from about 5000 years B.P. to perhaps as recently as the past 200 years. The data indicate, however, that these nondipole sources must have been virtually absent between about 12,000 and 5000 years B.P. as they are at the present time.