DOI: 10.1016/j.palaeo.2020.109604
论文题名: Iron oxide characteristics of the Chinese loess-red clay sequences and their implications for the evolution of the East Asian summer monsoon since the Late Oligocene
作者: Zhao H. ; Qiang X. ; Xu X. ; Sun Y.
刊名: Palaeogeography, Palaeoclimatology, Palaeoecology
ISSN: 310182
出版年: 2020
卷: 543 语种: 英语
英文关键词: Chinese Loess Plateau
; Fed/Fet
; Lingtai
; Monsoon evolution
; Rock magnetism
; Zhuanglang
Scopus关键词: chemical weathering
; climate variation
; depositional sequence
; goethite
; hematite
; iron oxide
; maghemite
; magnetite
; Miocene
; monsoon
; Oligocene
; paleomagnetism
; paleosol
; pedogenesis
; proxy climate record
; red soil
; China
; Gansu
; Lingtai
; Loess Plateau
; Qinghai-Xizang Plateau
英文摘要: The most significant climatic change in East Asia involved the formation and evolution of the coupled monsoon-arid environmental system during the Cenozoic, which was dynamically linked to global cooling and the growth of the Qinghai-Tibet Plateau. However, our understanding of monsoon evolution since the Late Oligocene remains controversial due to differences in the interpretation of various environmental proxies from loess archives. In this study, the composition and relative abundance of pedogenic iron oxides of two eolian sequences from the Lingtai section and the Zhuanglang drill core were investigated using rock magnetic, optical spectroscopy, and geochemical analyses. The results indicate that while the composition of iron oxides in the Mio-Pliocene red clay and Quaternary loess-paleosol sequences is similar, the concentrations of magnetite, maghemite, hematite and goethite are quite different between loess, paleosol and red clay. The combination of magnetic proxies (magnetic susceptibility, Fed/Fet, and color a* values) reveals that precipitation and temperature played varying roles in driving pedogenesis and chemical weathering since the Late Oligocene. During the Late Oligocene to Early Miocene, the occurrence of relatively strong pedogenesis and chemical weathering was likely the result of high temperatures rather than high precipitation. The East Asian summer monsoon intensified during the Middle Miocene Climate Optimum (16.5–14.5 Ma), in response to global climatic warming; subsequently, during the Middle to Late Miocene, the monsoon intensity gradually weakened due to global cooling. After ~8 Ma, the summer monsoon strengthened substantially and reached a maximum during 4.5–2.6 Ma, possibly as a result of the uplift of the northeastern margin of the Qinghai-Tibetan Plateau during the Late Miocene. The monsoon intensity then commenced a decreasing trend in the Early Pleistocene, but then strengthened again after ~1.0 Ma. © 2020 Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/158593
Appears in Collections: 气候变化与战略
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作者单位: State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, 710061, China; Xi'an Institute for Innovative Earth Environment Research, Xi'an, 710061, China; CAS Center for Excellence in Quaternary Science and Global Change, Chinese Academy of Sciences, Xi'an, 710061, China; College of Urban and Environmental Sciences, Northwest University, Xi'an, Shaanxi 710127, China
Recommended Citation:
Zhao H.,Qiang X.,Xu X.,et al. Iron oxide characteristics of the Chinese loess-red clay sequences and their implications for the evolution of the East Asian summer monsoon since the Late Oligocene[J]. Palaeogeography, Palaeoclimatology, Palaeoecology,2020-01-01,543