Geochemical characteristics of gold mineralization of the Huai Kham On deposit, Sukhothai Fold Belt, Northern Thailand

Abstract

The Huai Kham On gold deposit is located in the central part of the Sukhothai Fold Belt, northern Thailand. The Sukhothai Fold Belt represents an accretionary complex formed by subduction and collision between the Indochina and Sibumasu Terranes. There are many small gold deposits in the Sukhothai Fold Belt; however, the styles and formation environments of those gold deposits are not clear. The geology of the Huai Kham On deposit consists of volcanic and volcanosedimentary rocks, limestone, and low‐grade metamorphic rocks of Carboniferous to Triassic age. Gold‐bearing quartz veins are hosted by volcanic and volcanosedimentary rocks. The quartz veins can be divided into four stages. The mineral assemblage of the gold‐bearing quartz veins of Stages I and II comprises quartz, calcite, illite, pyrite, native gold, galena, chalcopyrite, and sphalerite. Quartz veins of Stage III consist of microcrystalline quartz, dolomite, calcite, pyrite, native gold, and chalcopyrite. Veins of Stage IV consist of calcite, dolomite, chlorite, and quartz. Fluid inclusions in quartz veins are classified into liquid‐rich two‐phase (Types IA and IB), carbonic‐aqueous (Type II), and carbonic (Type III) fluid inclusions. The homogenization temperatures of Types IA and II fluid inclusions that are related to the gold‐bearing quartz veins from Stages I to III ranged from 240° to 280°C. The δ18O values of quartz veins of Stages I to III range from +12.9 to +13.4‰, suggesting the presence of a homogeneous hydrothermal solution without temperature variation such as a decrease of temperature during the formation of gold‐bearing quartz veins from Stages I to III in the Huai Kham On gold deposit. Based on the calculated formation temperature of 280°C, the δ18O values of the hydrothermal solution that formed the gold‐bearing quartz veins range from +3.2 to +3.7‰, which falls into the range of metamorphic waters. The gold‐bearing quartz veins of the Huai Kham On deposit are interpreted to be the products of metamorphic water.

Zircon Hf‐isotope constraints on the formation of metallic mineral deposits in Thailand

“…The mineral deposit types in this belt are sediment‐hosted gold, orogenic gold, and orogenic and epithermal polymetallic deposits (Figures 2 and 3; Crow and Zaw, 2011; Zaw et al ., 2014). The orogenic gold deposits in the belt generally occur in sedimentary and low‐grade metamorphic rocks, such as the Huai Kham On gold deposit in the Wang Chin district, Phrae Province and the Huai Yuak gold deposit in the Si Satchanalai district, Sukhothai Province (Figures 2 and 3; Khositanont, 2008; Khositanont et al ., 2009; Tangwattananukul et al ., 2020; Tangwattananukul, 2021). The orogenic gold deposits in the Doi Tung and the Ban Yan areas are characterized by free gold in quartz veins, veinlets, and stockwork (Figures 2 and 3; Arunsrisanchai and Potisat, 1992).…”

“…Several studies dedicated to the geochemical characteristics and classification of the mineral deposits suggest that the different types of ore deposits have a heterogeneous distribution in the various tectonic terranes. For example, porphyry‐related skarn copper–gold and iron and epithermal gold deposits are abundant in the Loei Fold Belt, located on the western margin of Indochina Terrane (Khositanont, 2008; Kamvong et al ., 2014; Salam et al ., 2014); orogenic gold and epithermal antimony deposits are common in the Sukhothai Fold Belt (Dill et al ., 2008; Khositanont, 2008; Khositanont et al ., 2009; Paipana, 2014; Tangwattananukul et al ., 2020); and S‐type granite‐related tin and tungsten deposits are found in the Inthanon Zone and the Sibumasu Terrane (Cobbing et al ., 1992; Charusiri et al ., 1993; Linnen and Williams‐Jones, 1995; Schwartz et al ., 1995; Yokart et al ., 2003). However, the relationship between the distribution of mineral deposits and magmatism, and the crustal evolution of Thailand have not been investigated in detail.…”