BOREHOLE GEOPHYSICS IN IGNEOUS AND METAMORPHIC ROCKS.

Activities in geothermal energy, radioactive and industrial waste disposal, mineral exploration, engineering geology, and lunar and deep crustal exploration have increased the need for borehole geophysics in igneous and metamorphic rocks. Because there is a lack of knowledge and experience in the application of borehole geophysics to these rocks, the U. S. Geological Survey is conducting research in this area. Examples presented in this paper demonstrate that it is possible to derive important information from geophysical well logs of igneous and metamorphic rocks.