Detrital zircon geochronology of Cambrian—Ordovician sedimentary rocks in southern Hunan—Northeast Guangxi area and its tectonic implications

In this paper, the authors studied detrital zircon geochronology of the Cambrian-Ordovician sedimentary rocks sampled from the southern Hunan to northeastern Guangxi area by using LA-ICP-MS and obtained 239 groups of effective age data, with the ages ranging from 3146 Ma to 474 Ma. Most of the data are concentrated in five periods, i.e., 2633-2473 Ma (peak value around 2500 Ma), 1880-1521 Ma (peak value around 1650 Ma), 1146-911 Ma (peak value around 970 Ma), 896-720 Ma (peak value around 800 Ma) and 682-474 Ma (peak value around 520 Ma). All the four samples recorded Paleoarchean-Mesoarchean information, and their ages are concentrated on 1146-911 Ma and 896-848 Ma, suggesting that the Grenville and Rodinia orogeny events profoundly influenced the study area. Moreover, the authors obtained a large number of ages representing the Pan-African time, implying that the global Pan-African event significantly affected the Cathaysia Block and its adjacent regions. Combined with previous researches, the authors hold that the study area is located in the southeast of the southwestern section of the collision orogenic belt between the Yangtze block and the Cathaysia block. The strata in the study area received material sources from the two blocks with the material from the Cathaysia block being dominant.