Ruby Mts - S. Carlin Trend (Wannamaker and Doerner, 2002, Ore Geol. Rev.)
Tullis et al. (Geol., 1996) Sawyer (J. Metam. Geol., 2001) Anisotropy: Stress or Fabric?
GB-CP Transition Zone models; uniform vs non-uniform rifting
OPPORTUNITIES - EM 1. Imaging of melt or high temperature zones in upper mantle. 2. Degree of mantle hydration if temperature constrained. 3. Ponding of basaltic melts in lower crust and release of fluids from crystallization. 4. Lower crustal conductor from 0.1-.4% hypersaline brines. 5. CGB lower crustal conductor strongly anisotropic, controlled by pre-B&R fabric. 6. CGB Mantle resistivity not resolvably anisotropic, compatible with ACMA T and dry conductivity. 7. GB-CP TZ upper mantle active, with melting, non-uniform extension; CPI and CGB upper mantle less active. 8. Crustal scale detachments imaged from fluidization. 9. Crustal scale normal faults hosting eq’s, ore fluid flow.
CHALLENGES - EM • 1. Footprint, sampling, aperature, quality, dimensionality. • 2. Must be interpreted in context (constraints on temperature, composition, metamorphic grade). • 3. Controls on domain, amplitude of lower crustal conductor. • 4. Relation between conductivity and seismic anomalies.