黄土磁化率的古气候意义对研究红土磁化率古气候意义的启示  

Paleoclimate implication of magnetic susceptibility in the loess-paleosol will enlighten studying on the paleoclimate of the red soils in southern China

作　　者：曾永耀[1] 赵博 ZENG Yong-yao;ZHAO Bo(LanZhou Resources and Environment Voc-tech College,Lanzhou 730030,China)

机构地区：[1]兰州资源环境职业技术学院,兰州730030

出　　处：《地球物理学进展》2020年第5期1717-1723,共7页Progress in Geophysics

基　　金：甘肃省高等学校科研项目(2020B320);甘肃省高等学校产业支撑引导项目(2019C-16)联合资助.

摘　　要：中国黄土是蕴含古气候信息最为丰富的晚新生代陆相沉积物,也是连续记录第四纪乃至中新世以来亚洲内陆气候演化的物质载体.20世纪80年代学界首次发现黄土-古土壤磁化率可以作为东亚夏季风强弱的代用指标之后,磁化率作为一种能简单、快捷反演古气候的代用指标,在全球很多黄土剖面不断得到证实,被广泛用于海陆气候对比和古气候重建.自此之后,有学者尝试将磁化率反演古气候的应用范围扩大到中国南方红土.然而目前能否将磁化率作为反演古气候的代用指标完全适用于中国南方红土依然存在很大分歧.显然要准确理解红土磁化率是否具有明确的古气候意义,需要首先研究黄土-古土壤磁化率之所以能作为古气候代用指标的物理化学机制是什么,以及红土沉积物是否和黄土一样具有相似的磁性矿物形成机理.因此本文以分析黄土-古土壤磁性增强的原因为逻辑基础,以总结黄土-古土壤磁性矿物的种类和粒度特征为研究切入点,讨论黄土-古土壤磁化率具有古气候意义的原因.在此基础上分析红土磁化率是否具有明确的古气候意义,亦即进一步研究黄土-古土壤的磁气候学理论是否完全适用于中国南方红土.Continuous late Cenozoic loess-paleosol sequences,preserving records of both and palaeoclimatic information,are widely distributed in northern China.And these aeolian deposits are important terrestrial archives to reveal the Asian monsoon and the aridification of the Asian interior.Since the magnetic susceptibility of the loess-paleosol rhythms had been firstly successfully correlated to the marine oxygen isotope records in the 1980 s.The magnetic susceptibility of the loess-paleosol is widely used as an indicator to reflect long-term variations in the East Asian summer monsoon.And then,as an easy measuring proxy record of palaeoclimate,magnetic susceptibility has been widely used in paleoclimatic research of the late Cenozoic loess-paleosol sequences in many parts of the world.Recently some scholars use magnetic susceptibility as a proxy record to deduce the palaeoclimate of red soils in southern China.However,if magnetic susceptibility can be used to deduce the paleoclimate of red soils in southern China,it is also a disputed question.Obviously,if magnetic susceptibility can be used as a tool to deduce the paleoclimate of red soils in southern China,there must be to study the reason why magnetic susceptibility can be used to deduce the paleoclimate in loess and to study if there is the same mechanism of magnetic mineral between loess and red soils in southern China.So analyzing the enhancement of magnetism in the paleosol is the premise of the paper.And summarizing the type and size characteristics of magnetic minerals is the premise of discussing the reason why magnetic susceptibility is used as an indicator to reflect the paleoclimate of the loess-paleosol.Finally,analyzing if magnetic susceptibility can be used as a tool to deduce the paleoclimate of red soils in southern China is the main research contents of the paper.

关 键 词：黄土-古土壤 中国南方红土 磁化率 古气候 

分 类 号：P318[天文地球—固体地球物理学]