This post is a summary and review of Murphy, B., Hjuizenga, J. and Bedrosian, P., 2022. Graphite as an electrically conductive indicator of ancient crustal-scale fluid flow within mineral systems. Earth and Planetary Science Letters. https://doi.org/10.1016/j.epsl.2022.117700

Summary

• Magnetotelluric (MT) imaging has shown an apparent connection between crustal-scale electrical conductivity anomalies and major magmatic-hydrothermal iron oxide-apatite/iron oxide-copper-gold (IOA-IOCG) deposits in Australia and the United States
• The exact cause of these anomalies has been unclear
• Murphy et al (2022), interpret the conductors to be the result of graphite precipitation from CO₂-rich magmatic fluids during cooling
• These fluids exsolved from mafic magmas at mid- to lower-crustal depths
• Saline magmatic fluids that could drive mineralization were likely derived from more evolved intrusions at shallower crustal levels
• The conductivity anomalies mark zones that once were the deep roots of ancient magmatic-hydrothermal mineral systems

Continue reading Unravelling the Mystery of Graphite-Rich Magmatic-Hydrothermal Mineral Systems: MT Imaging Results from Australia and the US →