[HCG32-P06] Implications for paleoenvironment and tectonic setting of Khujirt area, Northern Mongolia
Keywords:sedimentology, geochemistry, Mongolia
The average value of CAI for the samples is 82.8±1.6, reflecting intensive weathering in the source area. The plotted data on A-CN-K diagram displays that rocks in coal were sourced mainly from Early Permian andesite and basalt and Early Paleozoic granodiorite, which borders Khujirt syncline. It is also supported by AlO2O3/TiO2 (avg. 18.4±0.3) and TiO2/Zr (63.4±2.4) ratios. To infer tectonic setting, two multi-dimensional discrimination diagrams were used. The results suggest that the tectonic setting of Khujirt was foreland basin that was probably formed by closure of Mongol-Okhotsk Ocean. This finding is consistent with generally accepted tectonic history of the region. Low Rb/Sr (0.02-0.04) and high Sr/Cu (13.8-30.6) ratios of the studied samples indicate that arid climate condition was dominant during the deposition of Khujirt peat accumulation. This conclusion is supported by C-values of the samples range from 0.1 to 0.3 as well. Due to arid condition, salinity was high reflecting substantially high Sr/Ba ratio varying from 1.7 to 2.7.