Abstract: The Xuanlong-type iron deposits formed during the gap interval of Precambrian iron formation (Mid-Proterozoic, 1.8-0.8Ga), and its ore-forming environment remains ambiguous. Previous studies mainly focus on iron ores and their host rocks, including shales and dolostone. This study conducts comparative geochemical and silicon isotope studies on (ferruginous) quartz sandstones and iron ores, which was used to trace the provenance and the intensity of weathering, thereby facilitating further discussion of the formation environment of the Xuanlong-type iron deposits. Both the Xuanlong-type iron ores and the host rock (ferruginous) quartz sandstones in North China Craton has high Chemical Index of Alteration (CIA) and Plagioclase Index of Alteration (PIA) values, indicating that the source underwent intense weathering processes. Chondrite-normalized rare-earth element (REE) patterns of ferruginous quartz sandstones are characterized by enrichment in light rare-earth elements (LREE) relate to that heavy rare-earth elements (HREE) with negative Eu anomaly (Eu/Eu^*=0.65-0.71). The silicon isotopic compositions of quartz in (ferruginous) quartz sandstones are similar to those in iron ores, as well as those in quartz from granite granitic quartz. This suggests that the detrital quartz grains in both (ferruginous) quartz sandstones and iron ores may be derived from the weathering products of Archean granites. Both Fe and Mn are present in the cementation of (ferruginous) quartz sandstone, and MnO is positively correlated with TFe₂O₃, indicating that oxidation occurred in the marine surface layer during the deposition of (ferruginous) quartz sandstone, but the redox interface is very shallow. When combining with previous studies, we proposed that multiple oxynenation episodes may take place during the Mid-Proterozoic, which led to the absence of large-scale iron formations during this period.