Ahn Hyeon-Seon, Park Sujeong, Lim Jaesoo
Quaternary Environment Research Center, Climate Change Response Division, Korea Institute of Geoscience and Mineral Resources (KIGAM), Daejeon, 34132, Republic of Korea.
Department of Geological Science, University of Science and Technology (UST), Daejeon, 34113, Republic of Korea.
Sci Rep. 2024 Sep 12;14(1):21323. doi: 10.1038/s41598-024-72347-6.
Magnetic susceptibility enhancement (kE) is useful for reconstructing terrestrial paleohydroclimate variabilities. However, kE and its driving process(es) in the Korean Peninsula remain uninvestigated. Therefore, this study investigated two kEs of similar magnitudes, dated MIS 1 (Holocene) and late MIS 3 (~ 29-36 ka), from a paleosol sequence in the upland of paleo-fluvial terrace in the central Korean Peninsula. We observed increased ferri- and antiferro-magnetic mineral components,including ultrafine particles, and stronger chlorite weathering for the two kEs, suggesting pedogenic component predominance. The Fe-bearing (phyllo)silicate weathering mechanism proposed for the Chinese Loess Plateau sequences can explain the pedogenesis-induced kEs for the studied site. Superparamagnetic-domain (SPD) to pseudo-single-domain sized particles of pedogenic magnetite are likely major contributors to kEs. Moreover, we recognized the younger kE interval as more SPD contribution but less in total ferrimagnetic contribution, and more antiferromagnetic contribution than the older ones. The magnetic differences between the periods can result from vegetation cover impact and surrounding hydroclimate conditions, consistent with the recent suggestion for part of the southeast Chinese sites with relatively more rainfall. Consequently, our study provides a baseline for improving the relationship between mineral magnetic signals and local/regional hydroclimatic and environmental variabilities.
磁化率增强（kE）有助于重建陆地古水文气候变化。然而，朝鲜半岛的kE及其驱动过程仍未得到研究。因此，本研究调查了朝鲜半岛中部古河流阶地高地一个古土壤序列中两个大小相似的kE，分别为全新世 MIS 1期和MIS 3晚期（约29 - 36 ka）。我们观察到，这两个kE的铁磁性和反铁磁性矿物成分增加，包括超细颗粒，绿泥石风化更强，表明成土成分占主导。针对中国黄土高原序列提出的含铁（层状）硅酸盐风化机制可以解释该研究地点成土作用引起的kE。成土磁铁矿的超顺磁畴（SPD）到假单畴大小的颗粒可能是kE的主要贡献者。此外，我们认识到，较年轻的kE区间SPD贡献更多，但总铁磁性贡献较少，且反铁磁性贡献比老的kE区间更多。不同时期的磁性差异可能是植被覆盖影响和周边水文气候条件所致，这与最近对中国东南部部分降雨相对较多地区的研究结果一致。因此，我们的研究为改善矿物磁性信号与当地/区域水文气候和环境变化之间的关系提供了一个基线。
