Paleoproterozoic positive δ13C excursion recorded in the carbonatite of southeast Tarim Craton, northwest China

• The Aketashitage carbonatites have features aligning with crustal-origin carbonate rocks . • The remarkable positive δ 13 C excursion sets them apart from conventional carbonates. • They might be formed by the anatexis of metasedimentary marbles during peak metamorphism. • They underscore the potential impact of the Lomagundi-Jatuli event on the Tarim Craton . The Paleoproterozoic Aketashitage carbonatite of northwest China is one of few high-δ 13 C carbonatites worldwide. Its absence of associated alkaline silicate rocks positions it as an intriguing case for probing the complex formation process of carbonatites. To provide further constraints on the genesis of these carbonatites, we have executed an exhaustive study encompassing petrography, geochemistry, geochronology, and radiogenic-stable isotope analysis. The Aketashitage carbonatites exhibit complex intrusive relationships with surrounding wall-rocks and house a diverse array of xenoliths, unmistakably signifying their igneous origin. Their rare earth elements (REE) diagrams are characterized by a nearly flat pattern and pronounced positive Eu anomalies, indicating a significant impact from hydrothermal fluids. These carbonatites are notably deficient in REEs, Ba, Sr, U, Th, Nb, and Ta. Their 143 Nd/ 144 Nd ratios and εNd (t) values range from 0.5109 to 0.5111 and −8.13 to −6.11, respectively. Remarkably, their δ 13 C V-PDB values (V-PDB, Vienna Pee Dee Belemnite) are exceptionally elevated, ranging from +13.31 to +15.48 ‰, thereby setting them apart from typical mantle-derived carbonatites, which exhibit δ 13 C values below 0 ‰. These comprehensive geochemical traits diverge significantly from those of mantle-derived carbonatites but share striking resemblances with crustal-origin carbonate rocks. Moreover, petrographic and mineralogical analyses reveal indicators of regional metamorphism within these carbonatites, proposing their possible for formation through the anatexis of high-grade marbles during the peak metamorphic event of the Paleoproterozoic era. Coupled with determined formation ages, these results imply a potential connection of Aketashitage carbonatites formation to the collision and amalgamation of the supercontinent Columbia. Moreover, the notable δ 13 C enrichment observed in these carbonatites presents substantial evidence for the impactful reach of the global Lomagundi-Jatuli event on the Tarim Craton.