Recording Fidelity of Relative Paleointensity Characteristics in the North Pacific Ocean
Recording Fidelity of Relative Paleointensity Characteristics in the North Pacific Ocean
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DOI：
10.1029/2021jb022068
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发表时间：
2021-07
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影响因子：
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通讯作者：
C. Gai;Yanguang Liu;Xuefa Shi;Chunqing Sun;Xiaodong Jiang;Jianxing Liu;Yi Zhong;Qingsong Liu
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文献类型：
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作者：
C. Gai;Yanguang Liu;Xuefa Shi;Chunqing Sun;Xiaodong Jiang;Jianxing Liu;Yi Zhong;Qingsong Liu
北太平洋沉积物是地磁场和古环境演化的重要档案，但晚第四纪沉积序列在北太平洋的探索较少，因为一般较低的沉积速率和沉积物的年龄低于方解石补偿深度的挑战。来自北太平洋的NP 02岩心沉积物包含三个可见的火山灰层，分别被确定为To‐Of、Spfa‐1和Kt‐3火山灰。根据火山灰对比和一个放射性碳年龄建立了NP 02柱样的年龄模型，其平均沉积速率为11.6cm/kyr。磁性分析表明，占主导地位的两个剩磁载体，碎屑涡旋状态和生物单畴磁铁矿。两个剩磁载体携带的相对古强度（RPI）信号之间的可变深度偏移给NP 02岩心RPI记录增加了可忽略的年龄误差（<0.5 kyr）。观察到明显的RPI振幅变化，并根据年龄模型在岩心NP 02 RPI记录中识别出Rockall和Laschamp偏移。通过与其他RPI堆栈和记录的比较，进一步验证了核心NP 02 RPI记录的保真度，并且我们证明RPI变化可以帮助细化时间顺序。
North Pacific Ocean sediments are important archives of geomagnetic field and paleoenvironmental evolutions, yet late Quaternary sedimentary sequences in the North Pacific Ocean are less explored because of generally low sedimentation rates and the challenge of dating sediments deposited below the calcite compensation depth. Core NP02 sediments from the North Pacific Ocean contain three visible tephra layers, which are identified as the To‐Of, Spfa‐1, and Kt‐3 tephra, respectively. An age model for core NP02 is established based on tephra correlation and one radiocarbon date, which gives a mean sedimentation rate of ∼11.6 cm/kyr. Magnetic analyses suggest the dominance of two remanence carriers; detrital vortex state and biogenic single domain magnetite. Variable depth offsets between the relative paleointensity (RPI) signals carried by the two remanence carriers adds a negligible age error (<0.5 kyr) to the core NP02 RPI record. Pronounced RPI amplitude variations are observed, and the Rockall and Laschamp excursions are identified in the core NP02 RPI record based on the age model. The fidelity of the core NP02 RPI record is further verified by comparison with other RPI stacks and records, and we demonstrate that the RPI variations can assist in chronology refinement.