The Evolution of Permian Source-to-Sink Systems and Tectonics Implications in the NW Junggar Basin, China: Evidence from Detrital Zircon Geochronology

Abstract

The basin type of the Junggar Basin changed during the Permian, but the time constraint of the tectonic evolution remains unclear. Besides, the fan deltas developed in the Permian in the Mahu Sag in the northwestern of the oil-rich basin. However, the provenances of the sedimentary systems remain unclear. Based on petrology and detrital zircon U-Pb ages, this study investigates the source-to-sink systems evolution and tectonics implications. Abundant lithic clasts in sandstones with low compositional and textural maturity imply proximal sources. The dating results showed a dominant peak (310–330 Ma) and a secondary peak (400–440 Ma) in the northern Mahu Sag, only one peak at 295–325 Ma in the central Mahu Sag, several peaks at 270–350 Ma in the southern Mahu Sag, and multiple peaks at 370–450 Ma in the Zhongguai Uplift. Thus, the north-western Junggar Basin was divided into four major source-to-sink systems, with adjacent central West Junggar as the main provenance and northern and southern West Junggar as the secondary provenance. The proportion of sediment supply from the southern and northern West Junggar is higher during the Middle-Late Permian. It suggests that the source-to-sink systems show inheritance and evolve from a single provenance into a complex provenance, indicating the uplift of West Junggar. The tectonic inversion may occur early in the Middle Permian and the response to tectonic activity is stronger in the southern West Junggar than in the northern West Junggar.

Late Permian‐Early Triassic intracontinental tectonic inversion in the Junggar Basin, NW China: New insights from detrital zircon geochronology and seismic reflection data

“…Petrological data show that the Middle Permian-Lower Triassic sandstone samples in the Mahu sag are mainly lithic sandstones, containing a large number of poorly sorted and angular lithic clasts (Figure 8), indicating rapid near-source accumulation. The detrital zircon age patterns of Late Palaeozoic and Early Mesozoic sandstone samples reported from the Mahu sag (Chen et al, 2022;Tang et al, 2021b;Tang, Song, He, et al, 2022), on the northwestern margin of the Junggar Basin, are significantly different from those reported on the southern margin of the Junggar Basin (Yang et al, 2013). To reveal the temporal and spatial variation of the source regions, we compare the zircon U-Pb age patterns of the Middle Permian-Lower Triassic samples with magmatic rock ages in different parts of West Junggar terrane.…”