TEMPERATURE LOGGING IN MINERAL EXPLORATION

Although a number of parameters affect the temperature-depth profile i n a borehole, temperature measurements have been successfully used to detect and map fracture zones with moving water and massive sulfide mi neralization, and they have been used to map lithology. In drill holes without water flow, temperature gradient logs have been used to map l ithology where significant thermal conductivity contrasts exist betwee n different materials. Because of the high thermal conductivity of mas sive sulfides, temperature measurements show significant anomalies nea r or within mineralized zones and may be used successfully to locate s ulfide occurrences. Although temperature measurements may not replace conventional electrical methods in exploration for most massive sulfid e deposits, non-conducting and non-polarizable sulfides, such as sphal erite, may be explored for with temperature methods. Electrochemical r eactions within massive sulfide deposits may generate sufficient heat to be detected on the temperature-depth profile. Their detection provi des information to aid in interpreting self potentials within massive sulfide deposits. Field examples of four applications of temperature m easurements in mineral exploration are presented: (1) lithological map ping; (2) fracture detection; (3) direct detection of massive sulfides ; (4 ) use in correcting and interpreting other geophysical logs.