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ABSTRACT: Integration of Remote Sensing and Geobotany for the Discrimination of Altered and Unaltered Carbonate Lithologies in the Darwin Hills, California

David A. Mouat, Jeffrey S. Myers

In arid and semiarid regions, exploration geologists often have a highly diverse set of rock exposures with which to construct various models for exploration purposes. When remote sensing is used in an exploration strategy in these regions, the overlying vegetation cover offers little in the way of confusing signals that might interfere with the purpose of discriminating those rock types associated with precious metals. The vegetation is either ignored or considered as a nuisance in the process. Yet, the geologist might be able to take advantage of the scant vegetation by making the assumption that the vegetation, as an effective integrator of the environment, might lead the geologist toward those lithologies of interest.

This paper examines and develops a strategy using geobotanical relationships among vegetation factors and geologic factors associated with hydrothermal alteration in carbonate lithologies occurring in the Darwin Hills. This area, an important lead, silver, and zinc district, is located in an area of diverse carbonate lithologies in a semiarid region west of Death Valley. Ground vegetation composition and cover information was gathered for the altered and unaltered lithologies. Ground spectral information was gathered to characterize the vegetation and rock types. Several NASA aircraft overflights employing the NS001

Thematic Mapper simulator were gathered. Data from these flights were used to discriminate the carbonate lithologies. While some lithologies were directly differentiated, it was found that the vegetation associations were critical for the discrimination of the units.

AAPG Search and Discovery Article #90097©1990 Fifth Circum-Pacific Energy and Mineral Resources Conference, Honolulu, Hawaii, July 29-August 3, 1990