The B prospect is located at the southeast of the Chatree gold-silver deposit. The mineralization is hosted in the Late Permian-Early Triassic Chatree volcanic sequence consisting of volcaniclastic and volcanogenic-sedimentary rocks ranging in composition from basaltic andesite to rhyolite. At the study area, the total thickness of volcanic succession is about 300 meters, and the succession can be divided into 3 main stratigraphic units from bottom to top, namely 1) porphyritic andesite unit (Unit 3), 2) polymictic intermediate breccia unit (Unit 2), and 3) volcanogenic sedimentary unit (Unit 1). The ore zones are mainly confined to polymictic intermediate breccia and volcanogenic sedimentary units (Unit 1 and 2). At least 3 stages of mineralization have been identified, namely 1) quartz-pyrite (Stage 1), 2) quartz-chlorite-calcite-sulfide-electrum (Stage 2), and 3) quartz-calcite (Stage 3) veins/veinlets. Gold occurs chiefly in Stage 2 mineralization which is characterized by typical vein textures of low sulfidation epithermal deposit (e.g., crustiform, colloform banding, and comb textures). Pyrite is the primary sulfide mineral with minor sphalerite, chalcopyrite, and galena. Gold occurs as electrum with fineness ranging from 506 to 632. The hydrothermal alteration at B prospect is composed of 2 main types: (1) quartz-adularia (silicic alteration) assemblage close to ore zone and (2) adularia-quartz-illite-calcite-chlorite (phyllic alteration) assemblage distal to ore zone. Based on characteristics of mineral assemblages, textures, and alterations, the mineralization at B prospect can be classified as a low sulfidation epithermal gold-silver style deposit.

H-pit is one of the significant ore lenses of the Chatree mine in Thailand. Au-Ag mineralization mainly occurs as veins, stockworks, and minor breccias hosted by volcanic and volcaniclastic rocks. Disseminated pyrites are commonly present near mineralized veins in the hanging wall zone. This study aims to assess the acid rock drainage (ARD) potential and heavy metal content from the H-pit area. The results indicate that hanging wall rock is a potential acid-forming (PAF) material related to disseminated pyrite formed by hydrothermal alteration. In contrast, the footwall and ore zone materials are classified as non-acid forming (NAF). Because the ore zone has calcite in the veins, it may help buffer the material’s acidity. The results of heavy metal analysis reveal that the ore zone has significantly higher contents of As, Cd, Cu, Pb, and Zn than those in the hanging wall and footwall zones. Moreover, the hanging wall and footwall materials have exceeding values for As, Cd, and Zn compared to those in typical igneous rocks. These heavy metals are interpreted to be sourced from (1) the primary composition in base metal sulfides (e.g., Cu, Pb, and Zn), (2) the substitution of trace elements in sulfides (e.g., As and Cd), and (3) the substitution of trace elements in calcite (e.g., Mn), as evidenced in the EPMA results. In conclusion, the hanging wall rocks in this study containing high sulfur in proximity to the ore zone are a PAF material with heavy metal contaminant sources, whereas the footwall and ore zone materials have a lower potential to be such sources at the Chatree mine.

<p>The B prospect is located at the southeast of the Chatree gold-silver deposit. The mineralization is hosted in the Late Permian-Early Triassic Chatree volcanic sequence consisting of volcaniclastic and volcanogenic-sedimentary rocks ranging in composition from basaltic andesite to rhyolite. At the study area, the total thickness of volcanic succession is about 300 meters, and the succession can be divided into three main stratigraphic units from bottom to top, namely, 1) porphyritic andesite unit (Unit 3), 2) polymictic intermediate breccia unit (Unit 2), and 3) volcanogenic sedimentary unit (Unit 1). The ore zones are mainly confined to polymictic intermediate breccia and volcanogenic sedimentary units (Units 1 and 2). At least three stages of mineralization have been identified, namely 1) quartz -pyrite (Stage 1), 2) quartz-chlorite-calcite-sulfides-electrum (Stage 2) and 3) quartz-calcite (stage 3) veins/veinlets. Gold occurs chiefly in Stage 2 mineralization which is characterized by typical vein textures of low sulfidation epithermal deposit (e.g., crustiform, colloform banding, comb textures). Pyrite is a primary sulfide mineral with minor sphalerite, chalcopyrite, and galena. Gold occurs as electrum with fineness ranging from 506 to 632 ppm. The hydrothermal alteration at B prospect is composed of two main types: 1) quartz-adularia (silicic alteration) assemblage close to ore zone, and 2) adularia-quartz-illite-calcite-chlorite (phyllic alteration) assemblage distal to ore zone. Based on characteristics of mineral assemblages, textures, and alterations the mineralization at B prospect can be classified as a low sulfidation epithermal gold-silver style deposit. </p>