Miocene to Early Pleistocene Depositional History and Tectonic Evolution of the Issyk‐Kul Basin, Central Tian Shan

The Issyk‐Kul Basin (Kyrgyzstan), situated in the central Tian Shan Mountains, hosts the largest and deepest mountain lake in Central Asia. Erosion of the surrounding Terskey and Kungey ranges led to the accumulation of up to 4 km of sediment in the adjacent depression. Creation of the basin from regional shortening and uplift likely initiated around the Oligocene‐Miocene, yet precise age control is sparse. To better understand the timing of these processes, we obtained magnetostratigraphic age constraints on fossil‐poor, fluvio‐lacustrine sediments exposed south of Lake Issyk‐Kul, that agree well with previous age constraints of the equivalent strata outside the Issyk‐Kul Basin. Two 500–650 m thick sections comprised mainly of Chu Group sediments were dated at 6.3–2.8 Ma and 7.0–2.4 Ma (late Miocene to early Pleistocene). Together with reinterpreted magnetostratigraphic constraints from underlying strata, we find that syn‐tectonic deposition commenced at ∼22 Ma with average sedimentation rates