Late Permian to Early Triassic tectonic uplift of the Qinling Orogenic Belt in response to initial collision of the North and South China blocks: a sediment provenance analysis

Abstract

The tectonic uplift of the Qinling Orogenic Belt (QOB) records the collision of the North and South China blocks. This study employs sandstone petrography, detrital zircon UPb geochronology, paleogeographic reconstructions, and paleocurrent data, to investigate the provenance of sediments from Late Permian to Early Triassic strata in the Fengxian area of the QOB, and to understand tectonic evolution of the belt. Detrital zircons from the Late Permian Shilidun Formation and the earliest Triassic Xipo Formation show two primary age populations (Late Paleozoic and Neoarchean to Paleoproterozoic), with sediments likely sourced from recycled sedimentary strata in the southern margin of the North China Block (S-NCB). Detrital zircons from the upper Xipo Formation and the Early Triassic Renjiawan Formation are concentrated in two age populations (Early Paleozoic and Neoproterozoic), being primarily derived from the North Qinling Belt (NQB). These provenance data suggest that the S-NCB underwent uplift during the Late Permian and earliest Triassic while significant uplift commenced in the NQB during the late Early Triassic. These uplift patterns are consistent with an overstep thrust tectonic evolution model for the collisional margin. Combined with sedimentary records from both the northern and southern sides of the QOB, this study proposes that the initial collision between the North and South China blocks in the central QOB occurred during the Late Permian.