| Chlorite is a common alteration mineral in porphyry deposits, and its chemical composition is closely related to the physicochemical conditions during formation, rendering it a significant indicator for locating the hydrothermal center of porphyry deposits. To elucidate the mineral chemical characteristics and exploration significance of chlorite in the Songshugou gold mining area, North Qilian, this study investigates chlorite from the alteration zones of the West deposit in the Songshugou gold mining area. Based on systematic field geological surveys and detailed petrographic observations, the major and trace element compositions of chlorite in the West deposit were analyzed using electron probe microanalysis (EPMA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Chlorite can be classified into two types according to the hosting hydrothermal alteration zones: chlorite from the propylitic alteration zone (Chl-Ⅰ) and chlorite from the sericite-chlorite alteration zone (Chl-Ⅱ). The analytical results indicate that most chlorite is Mg-rich chlorite, with a minor proportion being Fe-chlorite. Chl-Ⅰ predominantly consists of clinochlore–chamosite, whereas Chl-Ⅱ mainly belongs to pennine–ripidolite. The substitution mechanisms of chlorite are primarily Tschermak substitution, di-trioctahedral substitution, and Fe-Mg substitution. The formation temperatures of chlorite range from 210 to 304 °C, with Chl-Ⅰ forming at 210–301 °C and Chl-Ⅱ at 251–304 °C. The contents of trace elements Ga, Li, Ni, and V in chlorite decrease with increasing distance from the hydrothermal center, while Sr content increases. In contrast, Mn and Zn exhibit an initial increase followed by a decrease with distance, peaking at 240–340 m from the hydrothermal center. The Ti/Sr ratio of trace elements decreases with increasing distance from the hydrothermal center. Based on the Ti/Sr ratio, the hydrothermal center of the West deposit in the Songshugou gold deposit is inferred to be located in the central part of the deposit and the southwestern surface area at a vertical depth of approximately 300–400 m, corresponding to an elevation of 3500–3600 m along profile A1-A2. Therefore, this study proposes that the spatial variations in Ga, Li, Ni, V, Mn, Sr, and Zn contents in chlorite, together with the Ti/Sr ratio, can serve as effective exploration indicators for the West deposit and its peripheral areas. |