Geology, mineralization, and alteration of B Prospect of the epithermal Au-Ag deposit in Central Thailand: A study on Chatree?s satellite deposit for future gold exploration

Abstract

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.

Mineralogical and Geochemical Characteristics of the H-Pit of the Chatree Gold Deposit, Central Thailand: A Case Study for Assessment of Acid Rock Drainage and Heavy Metal Sources

“…However, other geological characteristics, including textural features of quartz, alteration, and mineral assemblages, allow us to classify the H ore lens into a low-sulfidation epithermal deposit model, similar to other ore lenses presented in the Chatree deposit [28,30,31,33]. Furthermore, the H ore lens is considered to represent the deeper part of the epithermal system, as higher contents of base metal sulfides (i.e., chalcopyrite, galena, sphalerite) are found in the H ore lens compared to other lenses at the Chatree deposit [30].…”

“…This belt is the most important mineral belt in Thailand, especially for copper and gold resources. The significant copper and gold deposits of the belt include the Phu Lon (Cu-Au skarn) [24], Phuthep (Cu-Au skarn) [23,25], Phu Thap Fah (Au skarn) [26,27], Chatree (Au-Ag low-sulfidation epithermal) [28][29][30][31][32][33], Khao Phanom Pha (Au skarn) [21], Khao Lek (Fe-Cu skarn) [34], and French mine deposit (Cu-Au skarn) [35]. (c) Geological map of the Chatree deposit and the surrounding areas showing dominant volcanic and volcanogenic sedimentary rocks.…”