Data DOI: 10.1594/IEDA/100730
Citation:
Hevelyn dan Silva Monteiro, et al., (2017), A combined (U-Th)/He and cosmogenic 3He record of landscape armoring by biogeochemical iron cycling. Interdisciplinary Earth Data Alliance (IEDA). doi:10.1594/IEDA/100730
Title:
A combined (U-Th)/He and cosmogenic 3He record of landscape armoring by biogeochemical iron cycling
Abstract:
(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 (QF), 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.
Creator(s):
Hevelyn dan Silva Monteiro
Paulo Marcos de Paula Vasconcelos
Kenneth A. Farley
Date Available:
2017-11-10
Date Created:
2017-11-14
Keyword(s):
Regional (Continents, Oceans) (coverage scope)
Brazil, Quadrilátero Ferrífero (geographic location)
Resource Type:
Dataset
File Format(s):
text/plain
application/vnd.openxmlformats-officedocument.spreadsheetml.sheet
application/vnd.openxmlformats-officedocument.wordprocessingml.document
Data Curated by:
Version:
1.0
Language:
en
License:
Creative Commons Attribution-NonCommercial-Share Alike 3.0 United States [CC BY-NC-SA 3.0] URI: https://creativecommons.org/licenses/by-nc-sa/3.0/us/