REE enrichment in granite-derived regolith deposits of the southeast United States: Prospective source rocks and accumulation processes

By:  and 
Edited by: G.J. Simandl and M. Neetz

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Abstract

The Southeastern United States contains numerous anorogenic, or A-type, granites, which constitute promising source rocks for REE-enriched ion adsorption clay deposits due to their inherently high concentrations of REE. These granites have undergone a long history of chemical weathering, resulting in thick granite-derived regoliths, akin to those of South China, which supply virtually all heavy REE and Y, and a significant portion of light REE to global markets. Detailed comparisons of granite regolith profiles formed on the Stewartsville and Striped Rock plutons, and the Robertson River batholith (Virginia) indicate that REE are mobile and can attain grades comparable to those of deposits currently mined in China. A REE-enriched parent, either A-type or I-type (highly fractionated igneous type) granite, is thought to be critical for generating the high concentrations of REE in regolith profiles. One prominent feature we recognize in many granites and mineralized regoliths is the tetrad behaviour displayed in REE chondrite-normalized patterns. Tetrad patterns in granite and regolith result from processes that promote the redistribution, enrichment, and fractionation of REE, such as late- to post- magmatic alteration of granite and silicate hydrolysis in the regolith. Thus, REE patterns showing tetrad effects may be a key for discriminating highly prospective source rocks and regoliths with potential for REE ion adsorption clay deposits.

Additional publication details

Publication type Conference Paper
Publication Subtype Conference Paper
Title REE enrichment in granite-derived regolith deposits of the southeast United States: Prospective source rocks and accumulation processes
Year Published 2015
Language English
Publisher British Columbia Ministry of Energy and Mines
Contributing office(s) Eastern Mineral and Environmental Resources Science Center
Description 8 p.
Larger Work Type Book
Larger Work Subtype Conference publication
Larger Work Title Symposium on strategic and critical materials proceedings (British Columbia Geological Survey Paper 2015-3)
First page 131
Last page 138
Conference Title Symposium on Strategic and Critical Materials
Conference Location Victoria, BC
Conference Date November 13-14, 2015
Country United States