Paleoproterozoic collisional orogeny in Central Tianshan: Assembling the Tarim Block within the Columbia supercontinent

Abstract

The Central Tianshan region is a key to evaluate the Paleoproterozoic evolution of the Tarim Block and its correlation with the Columbia supercontinent. In this study, we present U–Pb age data on detrital zircons in Paleoproterozoic schists from Central Tianshan and employ the magmatic age spectra to probe the Precambrian history of the region. We use the U–Pb ages of metamorphic zircons to constrain the Paleoproterozoic collisional event of the Tarim Block, and to evaluate its link with the Columbia supercontinent. The age populations of the detrital igneous zircons and inherited cores show peaks at ∼2544Ma, ∼2397Ma, ∼2264Ma, ∼2161Ma, ∼1970Ma and ∼1882Ma, corresponding to the major tectonomagmatic events previously recorded in the Tarim Block. Combined with the results from previous studies, we conclude that the northern Tarim was an active continental margin from late Neoarchean to late Paleoproterozoic. Zircons in the Paleoproterozoic schists display a wide range of two-stage model ages (3.3–2.7Ga), revealing prolonged growth of juvenile crust in Tarim from late Paleoarchean to early Neoarchean. The tightly constrained age range of 1830–1788Ma (weighted mean 1808Ma) obtained from the metamorphic zircons and overgrowth mantles mark the timing of the thermal event associated with the final collisional orogeny along the northern margin of Tarim, coinciding with the assembly of the Columbia supercontinent.