DOI: 10.1002/2017JF004282
Scopus记录号: 2-s2.0-85042178921
论文题名: A Combined (U-Th)/He and Cosmogenic 3He Record of Landscape Armoring by Biogeochemical Iron Cycling
作者: Monteiro H.S. ; Vasconcelos P.M.P. ; Farley K.A.
刊名: Journal of Geophysical Research: Earth Surface
ISSN: 21699003
出版年: 2018
卷: 123, 期: 2 起始页码: 298
结束页码: 323
语种: 英语
英文关键词: (U-Th)/He dating
; BIF landscapes
; canga
; cosmogenic 3He
Scopus关键词: banded iron formation
; biogeochemistry
; cementation
; geochronology
; goethite
; iron oxide
; precipitation (chemistry)
; uranium series dating
; Brazil
; Minas Gerais
; Quadrilatero Ferrifero
英文摘要: (U-Th)/He geochronology and cosmogenic 3He in iron oxides reveal mineral precipitation ages as old as 55 Ma and exposure ages greater than 5 Ma for canga-cemented plateaus in the Quadrilátero Ferrífero, Brazil, showing that lateritic profiles overlying banded iron-formation (BIF) landscapes in tropical regions have a long history of surface exposure. The long-term erosion history obtained from cosmogenic 3He on BIF plateaus confirms that relic surfaces persist in the landscape for millions of years. Combined 3He and (U-Th)/He dating shows that cangas are preferentially goethite cemented by biogeochemical reactions in the subsurface. Importantly, pebbles of hematite-magnetite in colluvia or shallow creeks draining the canga-cemented plateaus record a much longer exposure history than in situ canga blocks, showing that even older duricrusts, now eroded, once blanketed these plateaus. Physically stable but biogeochemically dynamic, cangas armor the landscape by pervasive and recurrent iron cycling and cementation, slowing down the delivery of weathered BIF or friable hematite–magnetite ore to erosion. ©2018. American Geophysical Union. All Rights Reserved. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/114565
Appears in Collections: 气候减缓与适应
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作者单位: School of Earth and Environmental Sciences, University of Queensland, Brisbane, QLD, Australia; Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, United States
Recommended Citation:
Monteiro H.S.,Vasconcelos P.M.P.,Farley K.A.. A Combined (U-Th)/He and Cosmogenic 3He Record of Landscape Armoring by Biogeochemical Iron Cycling[J]. Journal of Geophysical Research: Earth Surface,2018-01-01,123(2)