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首页> 外文期刊>Earth and Planetary Science Letters: A Letter Journal Devoted to the Development in Time of the Earth and Planetary System >High-resolution paleomagnetic records from Holocene sediments from the Palmer Deep, Western Antartic Peninsula
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High-resolution paleomagnetic records from Holocene sediments from the Palmer Deep, Western Antartic Peninsula

机译：来自南极半岛西部帕尔默深部全新世沉积物的高分辨率古磁记录

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摘要

Thick Holocene sedimentary sections (>45 m) cored in the Palmer Deep by the United States Antarctic Program (USAP) and during Ocean Drilling Program (ODP) Leg 178 provide the first opportunity to examine past geomagnetic field behavior at high southern latitudes. After removal of a low-coercivity drilling overprint the sediments display a stable, single-component remanent magnetization. Two short cores that recovered the uppermost 2.6 m of sediment have inclinations that fluctuate about the present day inclination (-57°) measured at Faraday Station, and several features with wavelengths of 10 to 20 cm appear to be correlative. However, shipboard measurements of inclination fluctuations on split-core samples from three holes drilled at ODP site 1098 do not correlate well with each other, even though the intensity and susceptibility data correlate very well and he overall mean inclination for cores from each hole is consistent with the expected geocentric axial dipole (GAD) inclination. The correlation is improved dramatically by using inclinations measured on u-channels taken from the pristine center of a split core. Consequently, the anomalous directions and the resulting poor between-hole correlation of inclinations obtained from shipboard data can be attributed to coring-induced deformation, which is common on the outer edge of ODP piston cores, and/or measurement artifacts in the split-core data. Our preferred inclination record is thus derived from u-channel results. The upper ～25 m represents continuous sedimentation over the past 9000 yr, with an average sedimentation rate exceeding 250 cm/kyr (0.25 cm/yr). Given that remanence measurements on u-channels average over an interval <7 cm long, we obtained independent measurements of the paleo-geomagnetic field that average over only ～30 yr. This high-resolution record is characterized by an inclination that fluctuates within ±15° of the current GAD inclination.
机译：美国南极计划（USAP）和大洋钻探计划（ODP）期间，在帕尔默深层中部的厚全新世沉积剖面（> 45 m）在第178条腿上提供了第一个机会来检查过去在南高纬度地区的地磁场行为。去除低矫顽力钻孔叠印后，沉积物显示出稳定的单组分剩余磁化强度。在法拉第站测得的当前倾角（-57°）附近，有两个短岩心回收了最上层2.6 m的沉积物，其倾角波动，并且一些具有10至20 cm波长的特征似乎是相关的。但是，船上对ODP站点1098钻的三个孔的裂芯样品的倾角波动的船上测量值相互之间没有很好的相关性，即使强度和磁化率数据相关性很好，并且每个孔的岩心的总体平均倾角是一致的具有预期的地心轴向偶极（GAD）倾斜度。通过使用从分裂核心原始中心获取的u通道测量的倾角，可以显着改善相关性。因此，异常方向以及从船上数据获得的倾斜度的孔间相关性差，可归因于在ODP活塞芯的外缘常见的取芯引起的变形，和/或剖分芯中的测量伪影数据。因此，我们的首选倾斜记录是从u通道结果得出的。上部〜25 m代表过去9000年的连续沉积，平均沉积速率超过250 cm / kyr（0.25 cm / yr）。考虑到对u通道的剩磁测量值平均在<7 cm长的时间间隔内，我们获得了仅约30年平均的古地磁场的独立测量值。此高分辨率记录的特点是倾斜度在当前GAD倾斜度的±15°范围内波动。

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