The central Yunnan region represents a significant phosphate rock province located along the western margin of the Yangtze Craton. Phosphate deposits occur within the Lower Cambrian Yuhucun Formation, which consists of a carbonate—phosphatic rock succession. The primary lithologies include phosphate- bearing dolostone, phosphorite, and interbedded siliceous rocks. Siliceous rocks commonly occur as banded, massive, or lenticular layers, closely associated with phosphate- bearing dolostone or phosphorite beds. Due to their sensitivity to depositional conditions, siliceous rocks serve as key indicators for reconstructing paleoenvironments, facilitating stratigraphic correlation, and recording paleobiological evolution. Results:This study investigates the petrological and geochemical characteristics of siliceous rocks associated with phosphorites in the Chengjiang, Yiliang, and Luliang areas of central Yunnan. The results indicate that the Al/(Al+Fe+Mn) ratio is less than 0. 4 in the Chengjiang and Yiliang regions, whereas it exceeds 0. 4 in the Luliang area. Rare earth element (REE) distribution patterns exhibit a gentle leftward trend, with pronounced negative Ce anomalies and low Ti concentrations. Total REE contents are relatively low, with slight enrichment in heavy rare earth elements (HREE). The U/Th ratios range from 1. 0 to 8. 8, all exceeding 1, indicating an oxidizing depositional environment. The Co/Ni ratios vary between 0. 04 and 0. 27, suggesting Ni enrichment relative to Co. Geochemical data suggest that siliceous rocks in Chengjiang and Yiliang are predominantly of hydrothermal origin, whereas those in Luliang are mainly biogenic. These siliceous rocks are spatially and temporally associated with phosphorites. Integrated with regional geological evidence, this study proposes that the extensive phosphate deposits along the Xiaojiang fault zone originated from submarine exhalative hydrothermal activity, leading to the formation of super- large phosphate accumulations such as those at Chengjiang, Kunyang, and Zhenxiong. In contrast, the Luliang area lies farther from the hydrothermal center, resulting in limited hydrothermal influence. Conclusions: The formation of siliceous rocks in the Luliang area is closely linked to planktonic activity, and the genesis of its small- scale phosphate deposits is primarily biogenic. Submarine exhalative hydrothermal fluids likely provided favorable thermal conditions for the early Cambrian biological radiation. Moreover, the substantial input of phosphorus from hydrothermal sources supplied essential nutrients, creating optimal conditions for both large- scale phosphogenesis and the rapid diversification of life during the Early Cambrian, exemplified by the Chengjiang biota.