Geochemical characteristics and indication of graphite deposits in Xinrong Region, Shanxi, China

The NE–SW-trending graphite belt found in the Xinrong Region, Datong City is one the richest graphite reserves in China, extending for more than 22 km. The ore-bearing layer of the Huangtuyao Formation is a graphite-bearing gneiss. Based on major and trace element analysis data, we determined from three diagrams that the graphite-bearing gneiss is a parametamorphic rock, and this gneiss was formed by the regional metamorphism of carbonaceous argillite. The detritus of this ore deposit originated from an arc region as seen from the K 2 O/Na 2 O–SiO 2 diagram. According to the Ta/Yb, Sr/Yb and K 2 O/Na 2 O ratios as well as the composition of Gehuyao gneiss, we concluded that this gneiss has typical low-potassium adakitic rock characteristics. Combined with the MgO/SiO 2 diagram and the characteristics of low K 2 O and high Al 2 O 3 , the genetic model of Gehuyao gneiss is melted subducted oceanic crust. Based on regional geological data and comparison of samples, we found an inherent relationship in the main composition content between the graphite-bearing gneiss and the Gehuyao gneiss. This indicates that the ore deposit accumulated the weathering products of Gehuyao gneiss during the sedimentary period. This research provides evidence for ore body evolution and makes it possible to establish the sedimentary–metamorphic model of the graphite ore in this region. In light of the range of the ore body, we predict that the potential area for graphite mineralization in the North China Craton was 2 ± 1.5 km away from the boundary. Thematic collection: This article is part of the Applications of Innovations in Geochemical Data Analysis collection available at: https://www.lyellcollection.org/cc/applications-of-innovations-in-geochemical-data-analysis