Paleomagnetic Secular Variation and Relative Paleointensity During the Holocene in South China—Huguangyan Maar Lake Revisited
Paleomagnetic Secular Variation and Relative Paleointensity During the Holocene in South China—Huguangyan Maar Lake Revisited
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DOI：
10.1029/2018gc008106
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发表时间：
2019-06
期刊：
影响因子：
3.7
通讯作者：
Mei Sheng;Xishen Wang;M. Dekkers;Yun Chen;G. Chu;L. Tang;J. Pei;Zhenyu Yang
中科院分区：
文献类型：
--
作者：
Mei Sheng;Xishen Wang;M. Dekkers;Yun Chen;G. Chu;L. Tang;J. Pei;Zhenyu Yang
东亚尤其是低纬度地区可靠的古地磁长期变化（PSV）记录的缺乏阻碍了更好地了解全球 PSV 机制。在此，我们报告了从中国亚热带-热带南部高沉积率湖光岩玛珥湖 (HML) 收集的约 6.7 米长的复合岩心的放射性碳测年全新世 PSV 记录。岩石磁性结果表明，自然剩磁存在于单畴磁铁矿中。在 u 通道样品上以 1 厘米间距进行的交变场退磁实验揭示了六个不同的倾角高点，分别位于公元前 7,500 年、公元前 5,100 年、公元前 4,600 年、公元前 3,600–3,400 年、公元前 1,600–1,200 年和公元 600–800 年；三个倾角低点分别位于公元前 4,800 年、公元前 600–300 年和公元 1,000–1,300 年；以及公元前约 3,600–3,200 年、约公元前 2,600–2,400 年和公元前 400 年至公元 200 年的三个东赤纬趋势。 HML PSV 记录与东亚其他独立测年记录和地磁场模型之间的相似性证实了我们的年龄模型和全新世 PSV 记录的稳健性。引人注目的是，在年龄不确定性范围内，HML 的百年到千年尺度的 PSV 特征与来自欧洲、北美和加拿大的其他全新世记录具有可比性，这表明这种方向模式可能是半球尺度的。尽管HML的相对古强度数据受到环境因素（如有机质成岩作用）的影响，但该记录仍然提供了一条具有区域重要意义的新PSV参考曲线，其显着特征可作为东亚古记录的地层标志。
The scarcity of reliable paleomagnetic secular variation (PSV) records from East Asia especially from low‐latitude regions impedes better understanding of global PSV mechanisms. Here we report on a radiocarbon‐dated Holocene PSV record from a composite ~6.7‐m‐long core collected from the high‐sedimentation‐rate Huguangyan Maar Lake (HML) in subtropical‐tropical South China. Rock magnetic results demonstrate that the natural remanent magnetization resides in single‐domain magnetite. Alternating field demagnetization experiments at 1‐cm spacing on u‐channel samples reveal six distinct inclination highs at ~7,500 BCE, ~5,100 BCE, ~4,600 BCE, ~3,600–3,400 BCE, ~1,600–1,200 BCE, and 600–800 CE; three inclination lows at ~4,800 BCE, ~600–300 BCE, and ~1,000–1,300 CE; and three eastward declination trends at ~3,600–3,200 BCE, ~2,600–2,400 BCE, and 400 BCE to 200 CE. The similarity between the HML PSV record and other independently dated records from East Asia and geomagnetic field models corroborates the robustness of our age model and Holocene PSV record. Strikingly, centennial‐ to millennial‐scale PSV features of the HML are comparable, within age uncertainties, with other Holocene records from Europe, North America, and Canada, suggesting that such directional patterns are likely to be hemispheric in scale. Although relative paleointensity data of HML are affected by environmental factors (e.g., organic matter diagenesis), the record still provides a regionally important new PSV reference curve whose conspicuous features may serve as stratigraphic markers for East Asian paleorecords.