Taking Full Use of Achievements of Remote Sensing and Geophysics in Exploration of Potash Deposit in China

2.1 Gamma-spectrometric well-logging Because of the gamma-radiation of natural isotope K40, radiometric geophysics is one of the few geophysical methods that can be used for direct detection of a certain element (Fig. 1). The gamma spectrometric well-logging and bore-hole gamma spectrometer were proposed and developed by us in 1963 which has been updated 5 times up to the 1980s. The 5 updates are: 205-shallow, 205-deep, NC-75, NC-76 and JHW-1. The gamma spectrometer well logging method and bore hole gamma spectrometers has been successfully applied in 6 provinces: the most effective results were obtained in Yunnan, Sichuan and Hubei provinces. Ischelite and glaserite (with 16.8% of KCl) were found by gamma-spectrometric well-logging in 1972. A bore-hole radioactivity-spectra interactive interpretation software system (HRSIS) was developed in 1995.