Structural, Mineralogical, and Geophysical Data Implications for the Development of the Salton Sea Magma-Hydrothermal System

Abstract

Structural, mineralogical and seismic reflection data from Controlled Thermal Resources (CTR) Hell’s Kitchen Project, and mineralogical and seismic reflection data from the EnergySource Minerals/Cyrq Energy Hudson Ranch Project, are incorporated into a geological model describing the dynamic Salton Sea magma-hydrothermal system. The resulting model predicts natural flow paths that extend to much greater depth than previously published numerical reservoir models, allowing better estimation of mineralized brine sourceregions, the fate of injected mineral-depleted brine, and Li depletion rates. Within this transtensional-dilational stepover basin, strain is accommodated by presently forming NNE striking structures and reactivation of earlier-formed NE and NW striking faults, accompanied by magma intrusions, thermally driven hydrofractures and seismicity, and development of the youthful oblique slip Brawley Fault. This system is well-described as a Hill-type mesh, with magmatism, high thermal gradients, high fluid pressures, and brine upflow centers coincident with stepovers. Temperature and mineralogical data obtained from XRD analysis demonstrate the dynamic nature of the thermal regime. Changes in mineral assemblages and mineral abundance with depth reflect the location of the high salinity brine dominating the reservoir, the temporal progradation of temperature, and zones of enhanced advective fluid transport.