Soil inorganic carbon (SIC) accounts for up to half of the global soil carbon stock and is mainly distributed in arid and semi-arid areas. However, our understanding on the drivers of vertical and spatial variations in SIC remains uncertain due to strong heterogeneity and data limitations. In this study, we conducted soil investigations across arid and semi-arid zones with climate gradients and surveyed 365 soil profiles. Statistical analysis, Shapley additive explanations and threshold detection were employed to quantify SIC variations and correlations between SIC and predictors. The average SIC density in this region was 2.78 kg/m2, which was more abundant at depths of 40-120 cm (3.34 kg/m2) than at 0-20 cm (1.31 kg/m2). Soil pH, depth and aridity were the key drivers of SIC variation, with the highest mean absolute Shapley values of 1.00, 0.63 and 0.35, respectively. The pH threshold affecting SIC variation was 7.7. Thresholds for SIC distribution occurred in both vertical and horizontal dimensions. Depths of initial SIC deposition are generally increase as aridity decreases, which was 28, 43 and 46 cm, with enhanced, reduced and uniform deposition occurring below this depth thresholds under hyper arid, arid and semi-arid zone, respectively. Aridity values below 0.62 marked SIC loss threshold at depths of 0-20 cm, whereas above 0.78 signified stable SIC accumulation threshold at depths of 20-40 cm. This research provides new insights into SIC formation and decomposition and benchmarks for modeling SIC dynamics in the context of climate change.