Geochemical Characteristics and Genesis of the Kujinggou Graphite Deposit in Weining Beishan, Ningxia

The Kujinggou graphite deposit is located in the southern area of Weining Beishan, Ningxia and Alashan Zuoqi, Inner Mongolia. The ore body is hosted in the regional metamorphic rocks of the Lower Carboniferous Chouniugou Formation, and the original rocks are sedimentary construction of shallow marine terrestrial clastic and carbonate rocks. The ore body is distributed in parallel layers in the metamorphic quartz sandstone, which is basically consistent with the stratigraphic production, with a near east-west orientation. The ore is mainly graphite-bearing carbonaceous slate with an average fixed carbon content of 5.53%. Graphite is mainly produced as irregularly scaled single crystals or as massive polycrystalline assemblages, mostly larger than 1 μm. Graphite ore is characterized by low Si, low alkali and high LOI as a whole, and trace element analysis shows enrichment of Rb, Ba and Sr. The ∑REE of graphite ore ranges from 101×10⁻⁶ to 137×10⁻⁶, with an average of 117×10⁻⁶, and the ∑REE of the host rocks is 42×10⁻⁶. The REE distribution patterns of both graphite ore and host rocks are high on the left and low on the right, and the ∑REE in graphite ore is higher than that in host rocks, which shows a high degree of REE differentiation in ore and host rocks in general, and a significant enrichment of LREE. The negative anomalies of Eu and Ce are obvious. The carbon isotope values of the graphite ore vary very little and are concentrated between −24.3‰ and −24.0‰, indicating that the carbonaceous source is mainly organic with some inorganic carbon involved. The genesis type of this deposit is regional metamorphic, and the shallow marine and lagoonal sedimentary environment makes the material basis for the graphite formation in Kujinggou, graphite formation is closely related to regional metamorphic deformation