MAKO LWIR HYPERSPECTRAL DATA ANALYSIS FOR FAULT STUDIES UTILIZING CORRELATION OF OFFSET PLUTONIC TERRAINS AND SOURCING OF ALLUVIAL DEPOSITS TO CROSS-FAULT DRAINAGE BASINS

Recently acquired Mako (The Aerospace Corporation) LWIR hyperspectral data over the South Bristol Mountains (SBM), Old Dad Mountains, and adjacent drainages, central Mojave Desert, California , is used to test the geologic materials identification capabilities of the instrument. The SBM Fault Zone (SBMFZ), part of the Miocene to recent Eastern California Shear Zone fault system, cuts obliquely through the range. The SBM have been mapped at 1:10k scale along the fault and at ~1:50k in the southern basement terrain. We compare the 2.7 meter pixel Mako data, over 700 square km, with existing detailed ground truth and use it for surficial identification in the adjacent regions. The high spatial and spectral resolution of Mako enables us to extend the mapping of key rock units and alteration zones, previously identified adjacent to the SBMFZ, throughout the range. The rock units include plutonic and metamorphic basement, effusive and explosive volcanic rocks, and sedimentary rocks, which exhibit differing spectral characteristics due to compositional and morphological variation, requiring customized analysis in each terrain. Identifiable carbonate signatures range from penetrative mineral scale carbonate alteration to pure bedded limestone; however, scene-dependent overcorrection of atmospheric absorption in the mid-range LWIR by in-scene atmospheric compensation (ISAC) as implemented in ENVI removes small percentage abundance signals of carbonate in some scenes.

In the full surface coverage Mako data, basement trends offset by the SBMFZ extend relatively continuously and linearly in map view away from the SBMFZ, supporting their use as total fault offset markers. In the heterogeneous southern basement terrain, range front drainages run perpendicular to the SBMFZ, and alluvial deposits can be classified as mixtures of their source region compositions. While the spectra of Quaternary and younger Tertiary terrace tops are heavily biased by the age dependent degree of 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 (up to 2 km) from their source drainages while younger units are not.