Fault-fluid interaction in porphyry copper hydrothermal systems: Faulted veins in radomiro Tomic, northern Chile

Jensen, Erik; Gonzalez, Gabriel; Faulkner, Daniel R.; Cembrano, Jose; Mitchell, Thomas M.

Abstract

The relationship between hydrothermal fluids and fault development is studied through a petrographic analysis of faulted veins in an open-pit copper mine, Radomiro Tomic (RT), northern Chile. Brittle deformation in RT was initiated with the formation of veins, disrupting low-strain crystal-plastic deformation. Following cooling, shear fractures propagated along these veins with associated fluid influx, leading to phyllic alteration. Hydrolysis converted all plagioclase to kaolinite within the damage zones and all orthoclase to illite within fault cores and the less deformed rocks surrounded by faults. In turn, precipitation of quartz and pyrite locally cemented gouge in the fault cores. Concentration of clays around faults and veins weakened the rocks and promoted shear strain along them. These processes are expected to occur in any porphyry-related hydrothermal system and can combine during the development of the system. Although cementation tends to strengthen fault cores, the overall strength of the faults is expected to be reduced by hydrolysis of plagioclase, reducing the friction of the faults and their capacity to accumulate stress. These findings may have strong implications for understanding the evolution of ore deposit, the rheology of the crust, earthquake generation, and natural hazard assessment.

Más información

Título según WOS: Fault-fluid interaction in porphyry copper hydrothermal systems: Faulted veins in radomiro Tomic, northern Chile
Título según SCOPUS: Fault-fluid interaction in porphyry copper hydrothermal systems: Faulted veins in radomiro Tomic, northern Chile
Título de la Revista: JOURNAL OF STRUCTURAL GEOLOGY
Volumen: 126
Editorial: PERGAMON-ELSEVIER SCIENCE LTD
Fecha de publicación: 2019
Página de inicio: 301
Página final: 317
Idioma: English
DOI:

10.1016/j.jsg.2019.06.013

Notas: ISI, SCOPUS