Abstract
At La Granja, Northern Peru, a granodiorite porphyry of probably Mid-Tertiary age intruded into an Upper Triassic to Lower Tertiary volcano-sedimentary sequence. It was followed by intensive hydrothermal alteration and cogenetic mineralization processes which influenced the intrusive body as well as its sedimentary cover and host rocks, producting hydrothermal alteration assemblages typical of porphyry Cu deposits (potassic, propylitic, phyllic, advanced argillic, silicic). The investigation of fluid inclusions showed that: (1) generally three types of fluid inclusions can be distinguished. Apparently coexisting vapour- and liquid-rich inclusions are taken as evidence for boiling in the hydrothermal system; and (2) the overall abundance of different inclusion types correlates well with different alteration types. The microthermometric data obtained fit well into the published range for other Cu porphyry deposits. Together with the petrographic data the following model of fluid and alteration development is proposed: Highly saline fluids of probably magmatic origin developed - possibly by dilution - towards a boiling system of moderate salinity, producing potassic alteration centers surrounded by propylitic alteration and/or skarnification. A younger low-salinity fluid regime affected the centers by overprinting phyllic and/or advanced argillic alteration. Silicification partly occurred during the latest stage of hydrothermal activity. Possible practical aspects of the fluid inclusion investigations are discussed.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
