Space Shuttle

A previously unprospected area, which was subjected to magma-heated steam and hot water tens of millions of years ago and is potentially rich in ore deposits, was located in remote Mexican desert by JPL infrared instrument carried on NASA's space shuttle, it was reported today.

The finding marks the first time that group of minerals typical of metal-rich areas has been pinpointed from space. The identification made by the shuttle-borne instrument was verified at the site in cooperative research last October by American and Mexican scientists. The project was sponsored on the Mexican side by the Secretario de Patrimonio Fermento Industrial.

The new results from the Shuttle Multispectral Infrared Radiometer (SMIRR) experiment, flown on the Columbia in November 1981, were reported at the International Symposium on Remote Sensing for Exploration Geology in Ft. Worth, Tex., by co-investigators Dr. Alexander F.H. Goetz of JPL and Dr. Lawrence C. Rowan of the U.S. Geological Survey, Reston, Va.

SMIRR measurements of the Baja California site were found to have identified iron oxide minerals as well as kaolinite (a clay), and possibly alunite (a potassium aluminum sulfate), as constituents in the surface materials in the area. These minerals are indicators of past hydrothermal activity and were probably formed at this site when volcanic rocks were subjected to hot circulating acidic waters and changed to clays, alunite and secondary quartz. Areas containing these minerals are high-priority exploration sites for gold, silver, copper, lead and zinc deposits.

The surface minerals identified by SMIRR are similar to those found in other large hydrothermal areas in the western United States.

The three-mile-diameter site is located in the mountainous central Baja California desert between Rosario on the Pacific side of the peninsula, and Bahia de los Angeles on the Gulf of California side. As there are no roads in the region, helicopters provided by the Mexican government were used to reach the desolate area. No known prospecting has been conducted in the area.

Dr. G.P. Salas, director of the Consejo Recurses Minerales and leader of the Mexican team, said that follow-up geophysical and geochemical measurements would be made to determine the ore potential for the area.

From the shuttle's payload bay, the instrument sampled 80,000 kilometers (50,000 miles) in swaths 100-meters (330-feet) wide circling the Earth.

SMIRR identified minerals by their reflectances in the infrared portion of the spectrum. In sampling four continents, the instrument identified limestone (a carbonate bearing rock), the clays kaolinite and possibly montmorillo nite from orbit. The results represent the first time minerals other than limonite (a common group of iron-bearing minerals) have been identified by spacecraft sensor.

SMIRR was developed for NASA's Office of Space Science and Terrestrial Applications.

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