--> ABSTRACT: Integration of Remote Sensing and Geototany for Mineral Exploration and Lithologic Discrimination, by David A. Mouat; #90097 (1990).

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ABSTRACT: Integration of Remote Sensing and Geototany for Mineral Exploration and Lithologic Discrimination

David A. Mouat

Mineral exploration in areas of vegetated terrain is often hampered by the vegetation: Rock outcrops are typically few and the vegetation obstructs access. When remote sensing is used in an exploration strategy, the vegetation is typically ignored. Yet, the remote sensing signal is derived predominantly from the vegetation. The geologist must examine structure or some other geologic attribute that appears through the vegetation. The science of geobotany presupposes that relationships exist among vegetation and geologic factors. If this assumption is valid, then by examining some attribute or attributes of the vegetation, the geologist can infer information that has value.

Two study areas have been established to illustrate the utility of geobotany and remote sensing for mineral exploration and lithologic discrimination. In the Josephine Ophiolite of southwest Oregon, a study area was established within which vegetation and lithologic information were obtained. Relationships relating the vegetation to the varying ultramafic and non-ultramafic lithologies were established. These showed close correlations between vegetation assemblages and a number of the lithologies. While the strongest correlations existed between the vegetation types and ultramafic and non-ultramafic lithologies, important relationships existed between the vegetation and the varying ultramafic lithologies. Remote sensing techniques based upon Landsat Thematic Mapper spectral bandpasses were used to discriminate the vegetation-defined rock types. Results are highly encouraging for the use of this strategy for the exploration of strategic and precious metals associated with an ophiolitic complex.

A second study area was established in west central California within the Fort Hunter-Liggett Military Reservation. In this area, aggregate is a critical mineral resource and techniques for its location are expensive and time-consuming. A strategy that involved the establishment of vegetation composition and phenological status ("greening up") relationships with aggregate resources and employing airborne Thematic Mapper imagery at the appropriate season. Results showed that sand and gravel aggregate sources were associated with vegetation that "browned off" sooner than other alluvial parent materials while residual aggregate sources had only a moderate correlation with vegetation composition. Remote sensing clearly identified both sources.

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