Integrated Geoelectrical Methodes Over Woxi Gold Deposit

The study area, Woxi gold-antimony, tungsten deposit, is located in Woxi town of Yuanling County of West Hunan, at 110° 54' E and 28° 32' N and with an area of 12 square kilometers, 114 km to the southwest of Changde City and 79 km to the east of Yuanling. Structures in the area can be divided into arc, WE-trending and NE-trending structures. The mining area is situated at the northeast wing of Xian'ebaodan Anticline. The outcropped strata are mainly the Proterozoic Lengjiaxi Group, Banxi Group and Sinian system as well as the Cambrian system. Under the role of early Wuling Movement, commonly known as the Dong'an Movement, the Lengjiaxi and Banxi Groups contacted in an incomplete angle.To study geology of the ore deposit, mapping geological structures and looking for new prosperous mineralized zones, geoelectrical methods including CSAMT, MT, and IP were employed. Scalar controlled-source audio magnetotellurics (CSAMT) survey was carried out over the Woxi deposit in two individual stages (A and B). For the first time in China, Tensor CSAMT was employed in the third stage (stage C). The CSAMT data provided important information about the mineralized layers and structures in the study area. Follow-up detailed geological mapping and drilling works verified most of the achieved results. In addition, RRI inversion was used as an effective method for producing 2-D resistivity images from CSAMT measurements made along surface traverses.Near-ore IP profiling results along three survey lines subjected to intensive drilling and geological studies show efficiency and reliability of the implemented CSAMT method.Pseudo-random multi-frequency IP sounding shows high conformity with the produced 2-D CSAMT models. The drilled boreholes based on the achieved results demonstrate the effectiveness of the combined use of both methodsMT data was collected in 11 stations on 20 km line with 2 km spacing to study deep structures of the region. The result shows a relatively deep concealed extension fault under the Woxi deposit.As indicated by employed integrated geoelectrical methods outcome, field geology and borehole data, some new faults were traced and mapped and two important large-scale reserves were explored in the area. The results of geophysical work along with fieldwork and borehole data directed us to new idea about geology of the deposit. In the offered model the concealed main fault in the area, named Wuhe (武赫) along with other main faults in the area such as Woxi Fault and other newly mapped, F2, F3, F4, and Ganziping faults are all were classified as normal faults in an extensional basin.Based on the proposed model, exploration should be carried out towards north of Ganziping and northwest of Xintianwan Faults. Meanwhile, prospecting in the east and west should also be paid close attention.