Proterozoic basin–orogen framework in the northern Tarim Craton, China

Abstract

The Tabei Uplift is the oldest unit in the Tarim Basin, but its initiation and evolution are unclear, which restricts our understanding of the Neoproterozoic basin–orogen framework of the northern Tarim Craton, and the breakup process at the margin of the Rodinia supercontinent. In this study, we analyzed U–Pb age spectra of detrital zircons from sedimentary rocks of the Tabei Uplift and surrounding regions. By integrating these data of outcrops, wells, and seismic investigation, we identify spatial–temporal changes in Neoproterozoic sedimentary provenances, establish a geological framework of basin–orogen structure, and elucidate the long-term evolution of the Tabei Uplift.Five sedimentary rock samples were dated by zircon U–Pb geochronology to constrain their depositional ages and regional stratigraphic correlations. Precambrian strata of Well YL1 in the Yuli region belong to the upper Cryogenian–lower Ediacaran (ca. 660 Ma); Precambrian strata of the Sawapuqi region belong to the Ediacaran (ca. 595 Ma); and strata of the Wikiritag region belong to the middle Paleozoic (ca. 410 Ma).Analysis of 3962 zircons from these 5 new samples and 54 published Neoproterozoic samples reveals temporal and spatial variations in their U–Pb age spectra. From the periphery of the northern Tarim Craton to the Tabei Uplift for a given period (such as the Tonian Aksu Group, Cryogenian, and Ediacaran), the proportion of Neoproterozoic zircons decreases, whereas the proportion of Neoarchean–Paleoproterozoic zircons increases. From the Tonian to the Ediacaran for a given location, the proportion of Neoproterozoic zircons decreases, whereas the proportion of Neoarchean–Paleoproterozoic zircons increases. Combining this information with a Neoproterozoic wedge structure in the northern Tarim Craton observed in three geological/seismic profiles, the North Tarim Orogen and adjacent rift basin are inferred to have formed simultaneously during the Neoproterozoic. The Proterozoic North Tarim Orogen served as the provenance for surrounding regions in the northern Tarim Craton. We propose two main phases of Proterozoic orogenesis in the northern Tarim Craton, during the Paleoproterozoic and Neoproterozoic. The Paleoproterozoic orogen was initiated at ca. 1.9–1.8 Ga and terminated at ca. 1.8 Ga, whereas the Neoproterozoic orogen was initiated at ca. 900–740 Ma and terminated at ca. 600 Ma. The temporal–spatial evolution of the Neoproterozoic basin–orogen framework in the northern Tarim Craton was closely related to the breakup process at the margin of the Rodinia supercontinent.