Coupling Mechanism of the Concealed Rock Body and Metallogenic Structure of the Sarakan Gold Deposit in Laos Investigated Using Magnetic and Electrical Methods

Abstract

The Sarakan Gold Deposit is located in the vicinity of the Songsanu and Napafa villages, north of Sarakan County, Vientiane Province, Laos. It forms part of the Luang Prabang–Loei polymetallic metallogenic belt, and its metallogenic geological conditions are good and mineral resources are abundant. At present, most orebodies (mineralization) are deeply buried and greatly vary in terms of their characteristics; furthermore, the distribution and output of orebodies (mineralization) are not clear, which makes it difficult to find minerals in the area. Based on the comprehensive geological characteristics, geophysical anomalies, and interpretation results in the study area, it is believed that the Sarakan Gold Deposit is closely related to Indosinian felsic substance magmatic intrusions and is controlled by their structure. The type of deposits in the belt are brittle–ductile, shear structured, Quartz-pyrite, vein-type gold deposits. In this study, we carried out comprehensive geophysical methods, including the high-precision magnetic survey, induced polarization survey, and the transient electromagnetic measurement. Based on the characteristics of geophysical anomalies, geological inference, and interpretation, the integrated geophysical and geochemical prospecting criteria of the ore area have been determined: high magnetism, high polarization, and medium–high resistance are the signs pointing to concealed mineralization bodies in the study area, and this provided the best framework for us to discuss the deep geological bodies in the study area. The drilling verification results are consistent with the abnormalities delineated by the magnetic and electrical measurements. Our geophysical exploration results revealed the coupling relationship between the concealed intrusive body of the Sarakan Gold Deposit and the metallogenic structure, which provided a great opportunity for finding potentially similar deposits in the Luang Prabang–Loei polymetallic metallogenic belt.