GPR measurements to detect major discontinuities at Cheshmeh-Shirdoosh limestone quarry, Iran

In recent years, the Iranian rich quarry industry has been looking for efficient scientific investigations to improve the extraction operations in different dimension stone quarries. Kerman Province is one of the most potential zones with a variety of dimension stone quarries near the city of Kerman. In this research, GPR measurements were carried out to detect major discontinuities at Cheshmeh-Shirdoosh limestone quarry, northeast of Kerman city. This quarry is being extracted by the diamond wire sawing method. As the first GPR study in Iranian quarries, a total length of about 1200 m was surveyed with 50 MHz and 250 MHz GPR antennas collecting data on the surface of the three extraction benches of the quarry. A 800 MHz antenna was also used to map the main defects of a block, which was extracted from a fractured section of the quarry. Six parallel profiles at 10 cm intervals were measured along one side of the block. The results obtained from the 250 MHz dataset were very encouraging and could detect all the major discontinuities. Interpreted profiles were also used to prepare depth slices of the density of joints for two main survey areas. As expected, GPR sections obtained from the 50 MHz antenna had a lower resolution but could clearly detect fault zones. The 800 MHz antenna could map the main defects of the extracted block. However, a higher frequency antenna (e.g., 2GHz or more) is recommended for mapping thin fractures.