Relative palaeointensity records from the Ontong-Java Plateau
Relative palaeointensity records from the Ontong-Java Plateau
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翁通爪哇高原的相对古强度记录
DOI：
10.1111/j.1365-246x.1994.tb02469.x
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发表时间：
1994
影响因子：
2.8
通讯作者：
N. Shackleton
中科院分区：
文献类型：
--
作者：
L. Tauxe;N. Shackleton
摘要 提供了从翁通爪哇高原 (OJP) 回收的岩心 RNDB 75p 的岩石磁性、古地磁和氧同位素结果。磁特性的高度均匀性以岩心上部 4 m 的浓度和晶粒尺寸变化相对较小为特征，加上归一化剩磁和岩石磁数据之间缺乏一致性，表明饱和剩磁归一化的自然剩磁反映了地磁场相对古强度的变化。 RNDB 75p 的记录复制了过去 400Ka 的其他 Ontong-Java 记录，并将记录扩展到大约 700Ka。 Ontong-Java 记录的光谱分析表明，相对古强度记录中存在周期性行为，主导周期在 30 至 40Ka 之间，这似乎不是岩性变异的产物。这个主导周期位于描述气候进动和地球轨道倾角变化的函数之间。然而，将归一化剩磁记录与天文进动（26 Ka 周期）进行比较要有利得多。尽管如此，将古强度记录“调整”为天文进动的记录似乎与从 SPECMAP 时间尺度得出的现有同位素年龄限制不一致。基于这些数据，我们必须在假设地球轨道控制冰量（在 SPECMAP 时间尺度中固有）和假设地球磁场由天文进动驱动之间做出选择。前一种假设具有坚实的理论和观测基础，我们更愿意将此处提供的数据解释为表明地球轨道在磁场调制中并未发挥可检测的作用。饱和剩磁和磁化率图对磁晶粒尺寸的细微变化非常敏感。在 RNDB 75p 中约 4m 处检测到伪单域晶粒尺寸范围内向多域（或超顺磁）场的轻微偏移。晶粒尺寸的这种变化可能反映了磁铁矿的成岩变化（例如溶解），并且可能与在该区域的其他岩心中检测到的深度处剩磁损失的现象有关。
SUMMARY Rock magnetic, palaeomagnetic and oxygen isotopic results are presented from core RNDB 75p, which was recovered from the Ontong-Java Plateau (OJP). A high degree of uniformity in magnetic properties characterized by relatively small changes in concentration and grain size in the upper 4 m of the core, combined with a lack of coherence between the normalized remanence and rock magnetic data suggests that the natural remanence normalized by saturation remanence reflects variations in relative palaeointensity of the geomagnetic field. The record from RNDB 75p replicates other Ontong-Java records spanning the last 400Ka and extends the record back to some 700Ka. Spectral analysis of the Ontong-Java record suggests periodic behaviour in the relative palaeointensity record with a dominant period of between 30 and 40Ka, which appears not be be an artefact of lithologic variability. This dominant period lies between functions describing climatic precession and obliquity changes in the Earth’s orbit. Comparison of the normalized remanence record with astronomical precession (26 Ka period), however, is much more favorable. None the less, ‘tuning’ the palaeointensity record to that of astronomical precession appears inconsistent with existing isotopic age constraints derived from the SPECMAP time-scale. Based on these data, we must choose between assuming that the Earth’s orbit controlled ice volume (inherent in the SPECMAP time-scale) and assuming that the Earth’s magnetic field is driven by astronomical precession. The former assumption has a substantial theoretical and observational base and we prefer to interpret the data presented here as suggesting that the Earth’s orbit has not played a detectable role in the modulation of the magnetic field. Plots of saturation remanence and magnetic susceptibility are very sensitive to quite subtle changes in magnetic grain size. A slight shift within the pseudo-singledomain grain-size range toward the multidomain (or superparamagnetic) field was detected at about 4m in RNDB 75p. This change in grain size may reflect a diagenetic alteration of the magnetite (such as dissolution) and may be related to the phenomenon responsible for the loss of magnetic remanence at depth detected in other cores from the region.
DOI：
10.1098/rspa.1953.0064
发表时间：
1953-01-01
影响因子：
--
作者：
FISHER, R
通讯作者：
FISHER, R