The genesis of the large Dabaiyang Au-Te deposit in the North China Craton: Insights from deposit geology, pyrite geochemistry and S-O isotope

The genesis of the Dabaiyang Au-Te deposit on the northern margin of North China Craton remain poorly constrained due to limitations of previous studies that were mainly based on bulk quartz δ 18 O isotope analyses and fluid inclusion microthermometry potentially affected by post-entrapment modification. Here, we presented an integrating study of paragenetic sequence, in-situ trace element and isotopic (δ 34 S and δ 18 O) analyses of pyrite and K-feldspar to decipher fluid source and evolution history. The δ 18 O values of pre-ore K-feldspar (8.2 to 9.6 ‰) and δ 34 S values of pre-ore pyrite (–5.5 to –0.1 ‰) indicate a magmatic source for the ore fluids, with negligible meteoric water input in the pre-ore stage. Trace element compositions of three pyrite generations (Py-1, Py-2a, Py-2b) reveal a two-stage gold enrichment process. The pre-ore stage was characterized by high-temperature, oxidized, and alkaline fluids, where Au was mainly incorporated as invisible gold into the As-rich Py-1. The syn-ore stage involved vigorous fluid boiling and mixing with meteoric water, leading to fluid cooling and the precipitation of visible native gold. The enrichment of gold during this stage was further facilitated by polymetallic Te-rich melts, accounting for the close association between native gold and tellurides. Integrating our results and previously published data, we propose that the Dabaiyang is more appropriately classified as an oxidized intrusion-related gold deposit, likely associated with a concealed Late Triassic granitic intrusion, rather than an epithermal system as previously suggested.