U-Pb geochronology, provenance and geological implications of Early Paleozoic volcano-sedimentary rocks in the Danghenanshan-Muli area, Central Qilian belt

Sedimentary basins related to the processes of plate subduction and collision in orogenic belt play a key role in tectonic reconstruction of the Qilian orogen. Seven samples for laser ablation ICP-MS U-Pb zircon dating were collected from Early Paleozoic volcano-sedimentary rocks in the Danghenanshan-Muli area. Our results indicate that : (1) Volcano-sedimentary sequences from the lower Wuligou Formation to the middle Yanchiwan Formation show characteristics of a backarc basin, while sedimentary rocks of the upper Duosuoqu Formation have characteristics of a foreland basin; (2) Basaltic andesite of the Wuligou Formation was formed at 472 +/- 10Ma, and depositional ages of the Yanchiwan and Duosuoqu formations are ca. 467 similar to 450Ma and 450 similar to 440Ma, respectively; (3) Detrital zircon U-Pb data and epsilon(Hf) (t) values of the Yanchiwan Formation show similar data to arc granitoids of the Central Qilian belt, while those of the Duosuoqu Formation record a source derived from associated volcanic rocks or granitoids of the South Qilian belt and the Precambrian material of the Central Qilian belt. These results suggest that Early Paleozoic volcano-sedimentary rocks in the Danghenanshan-Muli area was likely developed in a backarc basin and a foreland basin formed during the closure of the former.