Provenance analysis of the Ordovician sandstones in northern Sonid Left Banner area of Inner Mongolia and its geological significance

The petrology and zircon ages of the Ordovician sandstones in northern Sonid Left Banner area of Inner Mongolia were studied in this paper. The sandstones belong to a kind of lithic sandstone with lots of volcanic debris. The sandstone grain matrix component diagrams show that the sandstones came from the recycled orogenic belts. LA-ICP-MS dating technique was used to make detrital zircon analysis for one sandstone sample, and the age periods obtained are from low to high as follows: ①440~574Ma with the major peak at 506Ma and subordinate peak at 442Ma; ②650~799Ma with the peak at 767Ma; ③874~936Ma with the peak at 887Ma; ages of the other four zircon samples are 1145Ma, 1756Ma, 2618Ma and 2626Ma, respectively. Based on the comparison of ages and magmatic events with relative adjacent cratons and/or terrenes, the authors infer that the sandstones formed at 440Ma, and the provenances were mainly derived from the Erguna and Xing'an terranes, with the sedimentary process affected by volcanic events.