TIME CONSTRAINTS ON THE CLOSURE OF THE PALEO-ASIAN OCEAN U-Pb DATING AND Hf ISOTOPIC EVIDENCE FROM THE UPPER PALEOZOIC DETRITAL ZIRCON IN THE NORTHEASTERN ORDOS BASIN

The LA-MC-ICPMS U-Pb age test of detrital zircons was conducted on the Late Paleozoic strata samples in the Yulin area of the Ordos Basin. Meanwhile, we collected geochronology data of previous researchers obtained from rocks around the basin and compared them with our data from local samples. Together with our palaeocurrent direction data measured from the typical outcrops of the lower member, we performed a systematic analysis of the sedimentary provenance. The age of detrital zircon is mainly divided into three groups: 2550 similar to 2300 Ma (peak value of 2410 Ma), 2100 similar to 1700 Ma (peak value of 1840 Ma) and 360 similar to 283 Ma (peak value of 327 Ma). The first and second groups are reflections of the basement of the North China Craton. The Hf-176/Hf-177 ratios of the third group of detrital zircons range from 0.282171 to 0.282640, and the epsilon Hf (t) value ranges from -14.78 to 1.90. The age of the first-order Hf model is between 1586 and 908 Ma, and the age of the second-order model is between 2257 and 1217 Ma. It has dual Hf isotopic characteristics in the northern margin of the North China Craton and the Xingmeng orogenic belt, indicating that the northern margin of the North China Craton and the Xingmeng orogenic belt are the common provenance of the Late Paleozoic sedimentary strata in the Ordos Basin.