A 17,000 yr paleomagnetic secular variation record from the southeast Alaskan margin: Regional and global correlations
A 17,000 yr paleomagnetic secular variation record from the southeast Alaskan margin: Regional and global correlations
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DOI：
10.1016/j.epsl.2017.05.022
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发表时间：
2017-09
影响因子：
5.3
通讯作者：
M. Walczak;J. Stoner;A. Mix;J. Jaeger;G. Rosen;J. Channell;D. Heslop;C. Xuan
中科院分区：
文献类型：
--
作者：
M. Walczak;J. Stoner;A. Mix;J. Jaeger;G. Rosen;J. Channell;D. Heslop;C. Xuan
阿拉斯加湾边缘两个岩心的高分辨率沉积记录允许开发一个17,400年的古地磁长期变化（PSV）重建。这两个记录之间的一般协议，其独立的年表确认，当地PSV记录，表明这种档案，尽管复杂性，由于可变的沉积制度，沉积速率和成岩条件，提供有意义的信息过去的变化的地磁场。与其他来自东北太平洋的独立定年的沉积古地磁记录的比较表明，倾斜记录在很大程度上是一致的，这些倾斜记录结合在一起创建了东北太平洋沉积倾斜异常叠加（NEPSIAS），该叠加捕获了从阿拉斯加到俄勒冈州再到夏威夷的跨越30°经度和纬度的区域的共同信号。NEPSIAS与北大西洋（NNA）北方高质量磁偏角记录的比较表明，NEPSIAS的负（浅）倾角异常与NNA的东向磁偏角有关，而NNA的正（陡）倾角异常与NNA的向西向磁偏角有关。这些方向记录的区域地磁强度在过去的103000年在北美和欧洲/地中海地区近8000年的比较，是一致的北美和欧洲/地中海通量瓣的相对强度振荡的驱动机制。这些动态的持久性，通过全新世暗示了一个长寿的组织结构可能施加在地磁场的下地幔和/或内核。这些观测结果强调了北太平洋定向PSV与北大西洋定向PSV之间的基本联系，支持定向PSV作为年代地层工具进行长距离对比的潜力。
High-resolution sedimentary records on two cores from the Gulf of Alaska margin allow development of a ∼17,400-yr reconstruction of paleomagnetic secular variation (PSV). General agreement between the two records on their independent chronologies confirms that local PSV is recorded, demonstrating that such archives, notwithstanding complexities due to variable sedimentary regimes, deposition rates, and diagenetic conditions, provide meaningful information on past changes of the geomagnetic field. Comparisons with other independently dated sedimentary paleomagnetic records from the NE Pacific indicate largely coherent inclination records that in combination create a NE Pacific sedimentary inclination anomaly stack (NEPSIAS) capturing the common signal over an area spanning >30° longitude and latitude from Alaska through Oregon to Hawaii. Comparisons of NEPSIAS with high quality declination records from the northern North Atlantic (NNA) show that negative (shallow) inclination anomalies in NEPSIAS are associated with eastward NNA declinations while positive (steep) inclination anomalies in NEPSIAS are associated with westward NNA declinations. Comparison of these directional records to regional geomagnetic intensities over the past ∼3000 yrs in North America and back nearly 8000 yrs in the Euro/Mediterranean region, are consistent with a driving mechanism of oscillations in the relative strength of the North American and Euro/Mediterranean flux lobes. The persistence of these dynamics through the Holocene implicates a long-lived organizing structure likely imposed on the geomagnetic field by the lower mantle and/or inner core. These observations underscore a fundamental connection between directional PSV in the North Pacific with that of the North Atlantic, supporting the potential for long-distance correlation of directional PSV as a chronostratigraphic tool.