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首页> 外文期刊>Earth, planets and space: EPS >High-resolution evidence for dynamic transitional geomagnetic field behaviour from a Miocene reversal, McMurdo Sound, Ross Sea, Antarctica
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High-resolution evidence for dynamic transitional geomagnetic field behaviour from a Miocene reversal, McMurdo Sound, Ross Sea, Antarctica

机译：来自中新世逆转的动态过渡地磁场行为的高分辨率证据，麦克默多峡湾，南极罗斯海

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We report a high-resolution record of a Miocene polarity transition (probably the Chron C6r-C6n transition) from glacimarine sediments in McMurdo Sound, Ross Sea, Antarctica, which is the first transition record reported from high southern latitudes. The transition is recorded in two parallel cores through a 10.7 m stratigraphic thickness. The sediments are interpreted as having been deposited in a marine environment under the influence of floating ice or seaward of a glacier terminus from which a large sediment load was delivered to the drill site. The core was recovered using rotary drilling, which precludes azimuthal orientation of the core and determination of a vector record of the field during the transition. However, constraints on transitional field behaviour are provided by the exceptional resolution of this record. Large-scale paleomagnetic inclination fluctuations in the two cores can be independently correlated with each other using magnetic susceptibility data, which suggests that the sediments are reliable recorders of geomagnetic field variations. Agreement between the two parallel transition records provides evidence for highly dynamic field behaviour, as suggested by numerous large-scale inclination changes (～90°) throughout the transition. These large-scale changes occur across stratigraphically narrow intervals, which is consistent with the suggestion of rapid field changes during transitions. In one intact portion of the core, where there is no apparent relative core rotation between samples, declinations and inclinations are consistent with the presence of a stable cluster of virtual geomagnetic poles within the transition (although the possibility that this cluster represents a rapid depositional event cannot be precluded). These observations are consistent with those from other high-resolution records and provide a rare detailed view of transitional field behaviour compared to most sedimentary records, which are not as thick and which appear to have been smoothed by sedimentary remanence acquisition processes
机译：我们报告了南极洲罗斯海麦克默多峡湾冰川沉积物中中新世极性过渡（可能是Chron C6r-C6n过渡）的高分辨率记录，这是南高纬度地区首次报道的过渡记录。该过渡记录在两个平行的岩心中，地层厚度为10.7 m。沉积物被解释为是在浮冰或冰川终点向海的影响下沉积在海洋环境中的，大量的沉积物负载从这些沉积物输送到钻探现场。使用旋转钻孔回收岩心，这可以防止岩心的方位角取向和过渡过程中磁场矢量记录的确定。但是，此记录的特殊分辨率提供了对过渡场行为的限制。利用磁化率数据可以将两个岩心的大规模古磁倾角波动相互独立地联系起来，这表明沉积物是可靠的地磁场变化记录器。两次平行过渡记录之间的一致性为高动态场行为提供了证据，整个过渡期间发生了许多大规模的倾角变化（〜90°）。这些大范围变化发生在地层上较窄的间隔内，这与过渡期间快速场变化的建议是一致的。在岩心的一个完整部分中，样品之间没有明显的相对岩心旋转，偏角和倾角与过渡中存在稳定的虚拟地磁极簇相一致（尽管该簇代表快速沉积事件的可能性）不能排除）。这些观测结果与其他高分辨率记录的观测结果相符，并且与大多数沉积记录相比，这些过渡观测场的行为提供了罕见的详细视图，这些沉积记录不那么厚，并且似乎已被沉积残留物采集过程所平滑。

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