Detrital zircon U–Pb geochronology and Hf isotope data from Central Tianshan suggesting a link with the Tarim Block: Implications on Proterozoic supercontinent history

Abstract

The Central Tianshan, which is proposed to be part of the Tarim Block during Precambrian time, holds a pivotal role in the evolution of the Central Asian Orogenic Belt. In this study we employ detrital zircon age spectra to probe the Precambrian history of the region and to evaluate the link with the Proterozoic supercontinents. Detailed U–Pb zircon age data are reported for detrital zircons from Neoproterozoic metasedimentary rocks in the Baluntai region, the heartland of Central Tianshan. The metasediments here are dominated by zircons with major age populations of 2544–2394Ma, 1900–1500Ma, 1070–752Ma, ca. 560Ma and ca. 445Ma. The 2544–2394Ma ages correlate with the generation of continental nuclei in Tarim. The tectonothermal events during the periods of 1900–1500Ma and 1070–752Ma correspond to the assembly and breakup of the Columbia and Rodinia supercontinents. The magmatic ages represented by the age peak at ca. 560Ma correlate with those reported from the Late Neoproterozoic–Cambrian orogens in different fragments of the Gondwana supercontinent. The youngest age peak of ca. 445Ma is interpreted to represent the Caledonian orogenic event in Central Tianshan that is linked to the history of the Central Asian Orogenic Belt. Recyling of ancient crustal materials dominated, with minor input of juvenile materials during the above time intervals, with exception at ca. 2460Ma when significant addition of juvenile material occurred. A combination of U–Pb dating and Hf-isotope data in our study reveals that Central Tianshan was a part of the Tarim Block.