First Lead Isotopes Analysis of Fe–Cu Skarn Deposit of the Loei Fold Belt: Insight From Khao Thap Kwai Deposit, Lop Buri Province, Central Thailand

Fe–Cu skarns of the Loei Fold Belt have been poorly investigated in terms of lead isotopic signatures. We report the first MC‐ICP‐MS dataset from the belt, based on 15 ore samples from the Khao Thap Kwai deposit (Lop Buri, Thailand). Ores signatures display internally coherent yet dispersed signatures ( 206 Pb/ 204 Pb = 17.794–18.335, 207 Pb/ 204 Pb = 15.495–15.601, and 208 Pb/ 204 Pb = 37.628–38.256). The data plot between mantle and upper‐crust evolutionary fields and overlaps the orogenic growth curve; binary mixing between hydrous mantle‐derived arc melts and upper‐crustal reservoirs provides a parsimonious explanation. Regionally, Khao Thap Kwai field partly overlaps the Chatree epithermal system but shows distinctly lower 208 Pb/ 204 Pb ratios, whereas ore deposits of the Truong Son Belt are more radiogenic, highlighting the utility of Pb isotopes for discriminating metallogenic provinces in western Indochina.