河北坝上丰宁黄土剖面记录的230 ka BP以来的环境演化

发布时间：2018-06-21 12:20

本文选题：黄土 + 古地壤　；参考：《古地理学报》2017年04期

【摘要】：河北坝上地区位于东亚季风气候边缘区,对气候变化响应敏感。丰宁黄土剖面为研究该区域长时间尺度的环境演化提供了理想材料。通过丰宁黄土剖面地球化学元素和磁化率分析,结合光释光测年结果,恢复了该地区230 ka BP以来的环境演化历史;通过野外观察,识别出了S_1古土壤之下发育的风化淋滤黄土层,探讨了S_1古土壤发育时期的风化淋滤特征及其所揭示的气候变化问题。结果表明:(1)230 ka BP以来的磁化率记录可与深海氧同位素3—8阶段进行细节上的对比,表明丰宁黄土堆积区对全球气候变化有着积极的响应;(2)S_1古土壤发育时期,由于受到强降水的影响,土壤中元素受到强烈淋溶从而向下迁移到L_2黄土中,造成L_2上部地球化学记录与磁化率的差异;(3)从S_1古土壤顶部到钙结核层之间土壤属于酸性淋溶土,可能相当于现今中国北亚热带的黄棕壤,其剖面由土壤层、风化淋滤黄土层和CaCO_3淀积层构成;(4)S_1古土壤发育时期的温度和降水量与现今江苏泗洪和六合地区相当,表明当时研究区为亚热带气候。
[Abstract]:Bashang area is located in the edge of East Asian monsoon climate and is sensitive to climate change. The Fengning loess section provides an ideal material for studying the environmental evolution of the region on a long time scale. Based on the analysis of geochemical elements and magnetic susceptibility of Fengning loess section and the results of photoluminescence dating, the environmental evolution history of the area since 230 ka BP was restored, and the field observation was carried out. The weathering and leaching loess layer developed under the S-1 paleosol was identified, and the weathering and leaching characteristics and the problems of climate change revealed during the development period of the SSP _ 1 paleosol were discussed. The results show that the magnetic susceptibility records since 230ka BP can be compared in detail with the 3-8 stages of deep-sea oxygen isotopes. The results show that the Fengning loess accumulation area has a positive response to global climate change. As a result of heavy precipitation, the elements in the soil are strongly leached and migrated down to the L2 loess, resulting in the difference between the geochemical records and magnetic susceptibility in the upper part of L2. 3) the soil belongs to acidic leached soil from the top of SSP _ 1 paleosol to the layer of calcium nodules. It may be equivalent to the yellow brown soil in the north subtropics of China. Its profile is composed of soil layer, weathered leached loess layer and CaCO3 deposition layer. The temperature and precipitation during the paleosol development period are comparable to those in Sihong and Liuhe areas of Jiangsu Province. The results show that the study area was subtropical at that time.
【作者单位】：中国地质科学院水文地质环境地质研究所;中国地质科学院第四纪年代学与水文环境演变重点实验室;中国地质大学地球科学学院;中国地质大学地球物理与空间信息学院;
【基金】：中国地质科学院基本科研业务费专项(编号:YWF201411) 国家自然科学基金项目(编号:41602194)联合资助~~
【分类号】：P532

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