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GEOSOX: Geochronology of secondary oxide minerals in bedrock and fluid flow and deformation histories (GEOSOX)
Date du début: 1 août 2012, Date de fin: 31 juil. 2013 PROJET  TERMINÉ 

"Secondary Fe- and Mn-oxide minerals are common in crustal rocks, where they form by fluid flow long after initial formation of their host rocks. This fluid flow represents episodes of deformation, magmatic events, hydrocarbon migration, or topographic and climatic changes that drive groundwater flow. Understanding these processes constrains deformation, resources, hydrology, and landscape evolution.This proposal aims to determine deposition ages of Fe- and Mn-oxides from two geologic environments and to relate them via geochemical tracers to fluid migration processes. The two types of deposits to be studied are 1) vein hematite associated with deformation of crystalline rocks; 2) Fe- and Mn-oxide cements and concretions in sandstones. Preliminary analyses show that these are amenable to dating by (U-Th)/He, and their ages commonly reflect those of oxide formation related to known deformation or fluid flow episodes. This project will 1) improve dating methods for these types of secondary oxides, 2) understand the origin and significance of their compositional variability, and 3) document age-composition relationships in secondary oxides in regional transects in order to understand regional integrated fluid flow and deformation.Professor Reiners (Univ. Arizona) is an internationally renowned leader in low temperature thermochronology. The ideal way to transfer his expertise to the european geoscience community is via close collaboration with local researchers. This project, in developing the methodology for constraining fluid flow using secondary oxides, will transfer these skills to CRPG-CNRS through this collaboration. Funding is requested for Reiners to work at CRPG for 12 months. Reiners will initiate a workshop for master's level students on low temperature thermochronology, including a student exchange program. General public outreach activities will include involvement in ""La Fete de la Science"", Nancy (Oct. 2012)."