Gold occurrences are distributed across the Serrita–Salgueiro District in the Western Transversal Zone, Borborema Province, Brazil. Host rocks include sulfide-bearing quartz veins in metasedimentary units of the Salgueiro Complex and quartz-monzodiorites, granodiorites, and tonalites of the Serrita Suite. In both areas, gold is hosted in quartz veins arranged in extensional fractures, sheeted veins, and hydrothermal breccias. These veins are 0.1–1.5 m thick, vertical to subvertical, and oriented dominantly NW–SE, with E–W, NE–SW, and NNW–SSE sets also present. In Salgueiro, gold occurs both free in quartz and as inclusions in pyrite, chalcopyrite, and arsenopyrite, with hematite and martite subordinated; in Serrita, gold is associated with pyrite, chalcopyrite, centimeter-scale galena, and locally Hg-bearing electrum. Gold particles from Salgueiro show Au = 44–92.5 wt% and Ag = 6.8–51.5 wt%; in Serrita, Au = 74.4–94.7 wt% and Ag = 6–22 wt%. Fineness ranges from 770 to 930 (average 875) in Serrita and from 461 to 930 (average 707) in Salgueiro. Potassic to phyllic-like K-feldspar–muscovite ± fluorite halos adjacent to granites indicate F-rich magmatic–hydrothermal inputs, whereas major shear zones and chlorite–carbonate ± sericite ± cordierite halos in metasediments are consistent with shallow orogenic conditions. Taken together, we propose a mixing-dominated model in which magmatic–hydrothermal fluids exsolved from reduced intrusions interacted with metamorphic–orogenic fluids in epizonal conditions to precipitate gold.
