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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Harsh or balmy weathering conditions onto the first continent surface?

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Author(s):
Fabre, Sebastien [1] ; Jean Antonio, Paul Yves [2] ; Le Hir, Guillaume [3]
Total Authors: 3
Affiliation:
[1] Univ Paul Sabatier, IRD, IRAP, CNRS, 14 Ave Edouard Belin, F-31400 Toulouse - France
[2] Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer IAG, Rua Matao 1226, BR-05508090 Sao Paulo, SP - Brazil
[3] IPGP Bur, 130-1 Rue Jussieu, F-75238 Paris 05 - France
Total Affiliations: 3
Document type: Journal article
Source: Precambrian Research; v. 353, FEB 2021.
Web of Science Citations: 0
Abstract

The weathering conditions prevailing during Proterozoic times differ likely from Present-day ones mainly because of the climate conditions driven by high CO2 atmospheric levels. The question of weathering intensity onto one of the first continent surface, so-called ``Columbia{''}, is here addressed using the combination of a thermochemical and climatic model. Based on the dissolution of a mix of silicates representative of the presumed fresh rocks and the precipitation of secondary phases, the plausible reaction pathways of weathering seem to indicate that approximately 10% of initial silicates minerals should be dissolved to explain the measured high Chemical Index of Alteration (CIA), classically measured in the rocks belonging to this geological period. In addition, global climatic simulations were performed to evaluate the respective contributions of pCO(2), pluviometry, temperature and topographic parameters upon the weathering intensity. This finding could suggest the weathering intensity have been, at the very most, two orders of magnitude greater than tropical present-day one over the Paleoproterozoic era: the runoff seemed to be similar whereas the dissolution reaction extent was enhanced. These calculations are confronted with the geological record of weathering conditions, namely well-preserved sandstone deposits belonging to the 1.9 Ga Roraima Supergroup in the Guiana Shield, Brazil. The field data indicating very high Chemical Index of Alteration are in line with the model calculations. (AU)

FAPESP's process: 18/23755-0 - Testing the Amazônia-West Africa connection: new paleomagnetic poles for West Africa
Grantee:Paul Yves Jean Antonio
Support Opportunities: Scholarships abroad - Research Internship - Post-doctor
FAPESP's process: 17/18840-6 - Testing the Amazônia-West Africa connection and true polar wander in the Neoproterozoic
Grantee:Paul Yves Jean Antonio
Support Opportunities: Scholarships in Brazil - Post-Doctoral