Timing of the Erlangping back‐arc basin in the Qinling orogen, central China and its tectonic significance

Abstract

Back-arc basins hold the key in understanding the geodynamics of orogenic processes. The Qinling-Dabie orogenic belt in central China is one of the most important orogenic belts constraining the tectonic framework of eastern Asia. However, its Palaeozoic accretionary processes remain equivocal, mainly derived from the age uncertainty of the back-arc basin in the Qinling orogen. We carried out zircon U-Pb geochronology for two pyroclastic volcanic rocks intercalated within the Erlangping back-arc basin basalts. They yield U-Pb ages of 435.8 ± 4.2 Ma and 435.7 ± 3.8 Ma, which precisely constrain the timing of the back-arc basin opening. The opening of the Erlangping back-arc basin might have been triggered by the rollback of the Proto-Tethyan oceanic slab due to the southward migration of arc magmatism at ca. 440 Ma. The Palaeozoic tectonic evolution and orogen-scale geodynamic processes of the Qinling orogen are thus reconstructed. S U PP O RTI N G I N FO R M ATI O N Additional supporting information may be found online in the Supporting Information section at the end of the article. Appendix. SIMS zircon U-Pb results and analytical methods for volcanic tuffs performed by a Cameca IMS-1280 secondary ion mass spectrometer (SIMS) at the Institute of Geology and Geophysics, Chinese Academy of Sciences (IGGCAS), Beijing, China; Wholerock geochemistry determined by Shimadzu sequential X-ray fluorescence spectrometer (XRF) and inductively coupled plasma mass spectrometry (ICP-MS) at the State

Ordovician tectonic transition from passive margin into peripheral foreland in the southern Ordos: A diagnostic insight into the closure of Erlangping Ocean between the North Qinling Arc and North China Block

“…Based on the biochronologic constraint of the coral genus Halysites , the age of the Erlongping Group was proposed to be no younger than the Silurian (Wang, 1989). Accordingly, some authors further proposed that the Erlangping back‐arc Ocean was sustained until the Silurian (Hu et al, 2019; Meng & Zhang, 2000; Ratschbacher et al, 2003; Wu & Zheng, 2013). However, the coral genus Halysites were sampled from the upper Damiao Formation overlying the pillow lavas and massive basalts of the Erlangping ophiolitic unit, and generally lived during the Ordovician–Silurian (Tong & Yin, 2006).…”

“…EAGE SUN et al and chronostratigraphic clues from the Erlangping Group (Hu et al, 2019;Wang, 1989), the latter viewpoint argued that the Erlangping Ocean should last until ca. 430 Ma.…”

“…The ophiolitic mélanges were intruded by the S-type Erlangping granitic pluton with zircon U-Pb age of 441 ± 0.7 Ma (Lu et al, 2003), proposing the time of accretion and/or collision along the Erlangping Suture to be no later than Ordovician (Dong & Santosh, 2016). Two zircon U-Pb ages of 435.8 ± 4.2 Ma and 435.7 ± 3.8 Ma for the pyroclastic volcanic rocks from the same sections (Hu et al, 2019) possibly constrain the age of the post-collisional sedimentary unit.…”

“…The closure time of the Erlangping back‐arc Ocean is more controversial varying from the late‐Ordovician (Dong, Zhang, Hauzenberger, et al, 2011; Liu et al, 2016) to the end‐Silurian (Meng & Zhang, 2000; Ratschbacher et al, 2003; Wu & Zheng, 2013). According to the Silurian biostratigraphic and chronostratigraphic clues from the Erlangping Group (Hu et al, 2019; Wang, 1989), the latter viewpoint argued that the Erlangping Ocean should last until ca. 430 Ma.…”