MAKO LWIR HYPERSPECTRAL SENSOR DATA AS A TOOL FOR IDENTIFYING TECTONIC DISPLACEMENT, MINERALIZATION AND ALTERATION: EXAMPLES FROM THE EASTERN CALIFORNIA SHEAR ZONE

Recent acquisition of 870 km²of Mako (The Aerospace Corporation) LWIR hyperspectral data over the South Bristol (SBM), Old Dad (ODM), and Marble (MM) Mountains, Mojave desert, has demonstrated the geologic materials identification capabilities of the instrument. The high spatial (2.7 m pixels) and spectral resolution (128 bands) of Mako has enabled us to extend the local mapping of key rock units and alteration zones at high resolution throughout the ranges.

The SBM fault zone (SBMFZ) and the Bristol-Granite Mountains fault zone (BGMFZ), in the eastern California shear zone system, strike NW through the SBM and between the SBM/ODM and Granite mountains. Full surface coverage from Mako has confirmed that offset basement trends identified adjacent to the SBMFZ extend relatively continuously and linearly in map view away from the fault in the SBM providing additional confidence for their use as total fault offset markers. Band ratio analysis utilizes high percentage but sub-pixel abundances of garnet, carbonate, and secondary silica that dominate single pixel spectra. Metasomatic alteration in Jurassic plutons can be identified by spectral unmixing. A best-fit estimate of 7.5 km of total offset along the main strand of the SBMFZ can be produced by combining multiple uncorrelated apparent offset markers from MAKO.

Alluvial deposits in range front drainages perpendicular to the southern SBMFZ can be classified as mixtures of their source region compositions. While spectra of younger Tertiary and Quaternary terrace tops are heavily biased by age dependent surface alteration, the high spatial resolution of Mako allows for derivation of undiluted alluvial signatures from inset terrace risers on the oldest deeply incised alluvial units, demonstrating that these older terraces have been offset from their heterogeneous source drainages while younger units have not, providing incremental fault slip markers for the SBMFZ where the fault is inferred beneath only minorly deformed younger Quaternary deposits.