Abstract:
The Mayidang, Tu'erkuli, Keyinnan and other graphite deposits in the Moqinwula area of the East Junggar Basin, Xinjiang, are newly discovered deposits with industrial value in recent years. Taking the Tu'erkuli graphite Deposit as the research object, this study carried out LA-ICP-MS zircon U-Pb dating and petrogeochemical analysis. Chronological results show that the ore-hosting stratum of this deposit formed at 334±9 Ma, and the graphite mineralization occurred at 313 Ma. The petrogeochemical characteristics are as follows: the graphite ore is enriched in lithophile elements such as Rb, Ba, Pb and Sr, and depleted in high field strength elements (HFSEs) including Th, Nb, Ta and Ti; the total content of rare earth elements (REEs) is relatively low, with ΣREE ranging from 52.16×10
−6 to 134.21×10
−6 and an average of 81.71×10
−6. These features indicate that the sedimentary materials of the ore-bearing rocks were derived from terrigenous clastic rocks, and the rocks formed in a neritic-epicontinental anoxic reducing sedimentary environment. Comprehensive research suggests that the ore-hosting stratum of graphite deposits in the Moqinwula area of East Junggar is the Lower Carboniferous Jiangbasitao Formation, which corrects the previous understanding that it belonged to the Upper Silurian-Lower Devonian Hongliugou Formation. This deposit is a contact metamorphic graphite deposit. Its genetic mechanism is as follows: under the superimposed transformation of late tectonic activities and magmatic intrusion, the organic matter in the carbon-bearing sedimentary rock series of the Lower Carboniferous Jiangbasitao Formation was activated, undergoing deoxidation and dehydrogenation reactions followed by recrystallization, and finally forming crystalline graphite.