Paleointensity during a chron C26r excursion recorded in west Greenland lava flows
Paleointensity during a chron C26r excursion recorded in west Greenland lava flows
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西格陵兰熔岩流记录的 C26r 时间偏移期间的古强度
DOI：
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发表时间：
2004
期刊：
影响因子：
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通讯作者：
A. Pedersen
中科院分区：
文献类型：
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作者：
J. Riisager;P. Riisager;Xixi Zhao;R. Coe;A. Pedersen
[1]我们目前Thellier的古强度数据Vaigat组熔岩喷发在磁时C26 r（年龄60 Ma）在格陵兰岛西部。详细的现场观测表明，熔岩是在流场中就位的，连续熔岩的发现记录了相同的古磁场（强度和方向），以及暗示相同岩浆源的相似成分。特别令人感兴趣的是一个140米厚的熔岩序列的31个熔岩记录距离古磁极160 °的横向方向。这些技术质量较好的古强度测定表明，在偏移期间平均古场强为35.0 ± 13.2 μT，略强于平均29.4 ± 14.5 μT的稳定极性无向场强。在夏威夷、加那利岛和日本的熔岩序列中也观察到了相对较强的地磁漂移场强度，这表明某些地磁漂移代表了强的局部非偶极场的周期，而不是偶极场明显减弱的异常反转。
[1] We present Thellier paleointensity data from Vaigat Formation lavas erupted during magnetochron C26r (age ∼60 Ma) in west Greenland. The lavas were emplaced in flow fields, as demonstrated by detailed field observations, the finding of consecutive lavas recording the same paleomagnetic field (intensity and direction), and similar composition suggestive of an identical magma-source. Of particular interest is a ∼140 m thick lava sequence of 31 lavas recording excursional directions that lie ∼60° away from the paleomagnetic pole. Thellier paleointensity determinations of good technical quality demonstrate an average paleofield of 35.0 ± 13.2 μT during the excursion, which is slightly stronger than the average 29.4 ± 14.5 μT stable polarity non-excursional field intensity. Relatively strong excursional field intensity has also been observed in lava sequences in Hawaii, Canary Island, and Japan, suggesting that some geomagnetic excursions represent periods of strong local nondipole fields rather than aborted reversals with significantly weakened dipole field.