Late Cambrian (∼490 Ma) Arc Volcanic Rocks of the North Tianshan of Kyrgyzstan: Age Constraints from U-Pb Zircon Dating

In the present contribution, we aim to better constrain the age of the oldest arc-related volcanic units in the North Tianshan of Kyrgyzstan (NTS) in order to improve our understanding of the early evolution of subduction systems in the western part of the Central Asian Orogenic Belt. We conducted zircon U-Pb dating (LA-ICP-MS) on andesitic tuffs from the Sultansary and Tashtambektor formations, which were previously believed to be of early Cambrian and middle Cambrian to early Ordovician age, respectively. The results reveal ages of 491 +/- 3 and 487 +/- 3 Ma for these formations, indicating that both units are of Late Cambrian age. We conclude that these volcanic rocks belong to a major magmatic arc that evolved on a heterogeneous basement in the NTS during the Late Cambrian and Early Ordovician.