Zircons from the Tarim basement provide insights into its positions in Columbia and Rodinia supercontinents

摘要

The positions of the Tarim Craton in two Precambrian supercontinents Columbia and Rodinia still remain unknown or controversial, as the craton is largely covered by desert in the central part and only sparse Precambrian basement rocks are scattered at its margins. In this contribution, we attempt to use new in situ zircon U-Pb ages and Hf isotopic data, combined with comprehensive compiled data from Precambrian basement rocks at its margins, to provide new insights into positions in two Precambrian supercontinents. Detrital zircon profiles of northern Tarim and southern Siberia are characterized by a peak at 2.0-1.8 Ga and the lack of 1.7-1.1 Ga zircons. Moreover, both the 2.0-1.8 Ga detrital zircons show remarkable similarities dominated by mostly negative epsilon Hf(t) values ranging from -15 to 0. In addition, 2.0-1.8 Ga collisional granitic rocks are exposed in two terranes. These suggest that northern Tarim likely collided with southern Siberia at 2.0-1.8 Ga during the assembly of Columbia. In southern Tarim, Neoproterozoic magmatic rocks were closely related with the evolution of Rodinia. The similar to 0.9 Ga Ma gneissic granites in Altyn Tagh area were formed in collisional settings due to the collision between southern Tarim and northern India during the assembly of Rodinia, which is supported by distinctly comparable zircon age spectra and Hf isotopes from Neoproterozoic strata in two terrenes. This model considers the Tarim Craton as a single block in the period from Columbia to Rodinia, which can explain different tectonomagamtic events in northern and southern Tarim.