Closure time in the East Qilian Ocean and Early Paleozoic ocean–continent configuration in the Helan Mountains and adjacent regions, NW China

Lithofacies and faunal assemblage affinities of the Helan Mountains and its adjacent blocks are explored using field investigations and analysis of previous results. The tectonic affinity between the Alxa Block and the North China Block is analyzed by means of LA-ICP-MS detrital U–Pb zircon age spectrums. The Early Paleozoic stratigraphic framework is constructed and stratigraphic contact relationships between the study area and its adjacent...