Spatial distribution of the critical mineral resource element titanium in China and its influencing factors

In China, titanium is found in multi-metal symbiotic ore deposits that present sorting difficulties, low recovery rates, high production costs, and low overall resource utilization rates. The concentration and distribution of titanium in the pedosphere must be better understood to assess the potential titanium resources. The China Geochemical Baseline project obtained harmonized soil and rock geochemical data covering mainland China and provided reliable data for 76 elements (including titanium) from 3382 top (0-25 cm) and 3380 deep (>100 cm) sediment or alluvial soil samples and 12,201 rock samples. In this study, titanium concentrations were determined by X-ray fluorescence spectrometry under strict quality control. The median titanium concentration values in the top and deep samples, which were considered geochemical baseline values, were 3498 mg/kg and 3406 mg/kg, respectively, with mean values of 3661 mg/kg and 3585 mg/kg, respectively. The titanium concentrations ranged from 266 to 24,674 mg/kg and 324 to 25,504 mg/kg in the top and deep soil samples, respectively. The 75 % range (Q25-Q95) of titanium concentrations in the rock ranged from 978 to 8299 mg/kg. The median titanium concentration was 2555 mg/kg in the rock samples, while the mean concentration was 3089 mg/kg. The geochemical map of titanium indicated that low titanium concentrations below Q25 (<3498 and 3406 mg/ kg in the top and deep samples, respectively) are primarily distributed in southern Xinjiang, Tibet, Qinghai, Gansu, and Inner Mongolia. The distribution of low titanium content in the soils is likely attributed to these regions being covered by deserts (e.g., Gobi) and glaciers. Soils with high titanium concentrations are widely distributed in the Emeishan large igneous province at the southwest margin of the Yangzi block, which is related to the large distribution of intermediate-basic rock in the area, as well as along the northeast-southwest direction of the Yangtze block, which extends for nearly 1600 km. Moreover, these soils are mainly associated with the black rock system and intermediate-basic dikes. Soil titanium concentrations are affected by various factors, including the occurrence of tectonic activity and distribution of the black rock system, intermediate-basic rock (especially basalt), and V-Ti magnetite deposits. In particular, the large igneous province area generated by a mantle column represents the main location of V-Ti magnetite deposit formation and the area with the highest titanium content. In addition to providing detailed information about the titanium distribution in the pedosphere and rock of mainland China, the project can also provide basic geochemical data for the development and utilization of titanium resources and the formulation of critical mineral industry policies.