Geochronology of detrital zircons and its geological significance for the Hekou Formation of Late Cretaceous in Tongtianzhai, Shicheng County, Jiangxi Province

Tongtianzhai is located in the Nanfeng-Huichang Mesozoic-Cenozoic basin of Shicheng County, Jiangxi Province. The Late Cretaceous Hekou Formation is mainly composed of a red clasolite series in continental alluvial fan, and can be divided into three sections, representing fan root, fan middle and fan margin sedimentary facies from bottom upwards. And the provenance was derived from two uplift erosion areas from the NW and SE direction based on the lithofacies paleogeographic analysis. The authors obtained 111 and 108 detrital zircon U-Pb ages from two samples in the Hekou Formation respectively using the LA-ICP MS geochronology. There are four age peaks in age spectrum. i.e., 104~137Ma, 400~418Ma, 750~752Ma, and 1854~1895Ma, which show four main tectonic thermal events in the source area. Thermal events in 1854~1895Ma and 750~752Ma may be the response to the meeting and parting of the Columbia and Rodinia supercontinent; thermal event in 400~418Ma was a response to the ocean-continent conversion of Huaxia orogenic belt; thermal event in 104~137Ma was a response of the tectonic magma event on the eastern margin of South China Plate resulting from the transformation of the western margin of the paleo Pacific plate into an active continental margin.