Application and Significance of Geological, Geochemical, and Geophysical Methods in the Nanpo Gold Field in Laos

Abstract

As the main part of the Indosinian metallogenic province in the eastern part of the Tethys metallogenic domain, Southeast Asia has experienced multiple stages of tectonic magnetic activities accompanied by the formation of rich mineral resources. However, due to the undeveloped economy, low degree of geological work, dense vegetation cover, and lack of obvious prospecting marks, traditional geological prospecting work in the area is not optimal. Consequently, the combination of high-precision geophysics and geochemistry has become an important method of looking for ore bodies deep underground in this area. The Nanpo gold deposit is a hydrothermal gold deposit that occurs in the Indosinian felsic volcanic rock body, and its mineralization is closely related to felsic magmatism. This study carried out comprehensive geophysical and geochemical exploration methods of soil geochemical survey, induced polarization (IP) survey, and audio-frequency magnetotelluric (AMT) survey. Based on the characteristics of geophysical and geochemical anomalies, geological inference, and interpretation, the integrated geophysical and geochemical prospecting criteria of the ore area have been determined: The large-scale and overlapping Au-Ag-Cu anomaly area in the host felsic magmatic rocks (mainly diorite, monzodiorite and granodiorite) is a favorable metallogenic area. Two anomalies, P1–H1 and P3–H6, with the best metallogenetic conditions and the deepest extensions of the known ore bodies, were further selected as engineering verification targets. After the study of the drill core, gold (mineralized) bodies consistent with the anomalies were found, indicating that the combined method is suitable for the exploration of mineral resources in this area, and the prospecting effect is good. At the same time, the metallogenic prediction shows that the deep part of the mining area still has great metallogenic prospects and prospecting potential. The characteristics of geophysical and geochemical anomalies and prospecting experience in the study area can provide references for the prospecting of hydrothermal gold deposits in the Luang Prabang–Loei structural belt.

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

“…There is a huge potential for large gold deposits. Owing to the low degree of geological prospecting and geological research in Laos, basic theoretical problems such as the evolution of the geological structure and the law of mineralization in the study area have not been sufficiently investigated [8,[21][22][23]. Although a small number of Au-Ag-Cu orebodies and a low amount of mineralization have been discovered in the study area, the shallow orebodies on the surface are smaller in scale and lower in taste [24][25][26].…”

“…Further, the induced polarization (IP) method is a relatively mature geophysical exploration method for finding sulfide mineral deposits [5,6]. It has a high working efficiency, fast surface-sweeping speed, and is relatively unaffected by topography [7][8][9]. The ores or mineralized bodies and surrounding rocks in the area have differing magnetic properties and electrical parameters, which indicates that there are certain prerequisites for the development of magnetic and Minerals 2023, 13, 912 2 of 18 IP methods, and the delineated magnetic anomalies and IP anomalies can be regarded as good prospecting signs.…”

Application of Audio-Magnetotelluric and Dual-Frequency Induced Polarization Joint Inversion in a Pb-Zn Deposit Exploration in Inner Mongolia, China

“…The development of electromagnetic (EM) geophysical methods in the 1950s has played a crucial role in mapping the lateral and vertical 2 variations in subsurface resistivity. These methods, such as natural source audio magnetotelluric (AMT) and controlled source (CSAMT), have found wide-range of applications in metallic mineral exploration [5][6][7][8][9], groundwater studies [10], and geothermal system investigations [11][12][13][14]. Induced polarization (IP) also has a longstanding history in geophysics, initially employed in the field of mining geophysics to delineate and localize ore bodies [15,16].…”

Depth Estimation of Sedimentary Sections and Basement Rocks in the Bornu Basin, Northeast Nigeria Using High-Resolution Airborne Magnetic Data

“…Potential field techniques have various successful applications in exploration geophysics [1][2][3][4][5][6][7][8][9][10]. One of the most essential applications of the magnetic dataset is to define the location and depth of magnetic bodies.…”