Apatite low-temperature thermochronology constraints on the Cenozoic differential uplift/denudation of the Ke'eryin lithium ore field in western China: Implications for lithium exploration

Abstract

The Ke'eryin pegmatite-type lithium ore field is a major lithium concentration area in the Songpan-Garze fold belt, western China. However, there is a notable spatial variability in lithium mineralization, with the northeastern and southeastern regions showing higher mineralization intensity than the western and northern parts. Previous studies suggest that this difference is likely related to the development of a Cenozoic thrust fault, the Ke'eryin thrust fault (KEYF), which traverses the eastern and southern parts of the ore field. However, direct chronological evidence is lacking. This study employs apatite fission track thermochronology on three representative deposits located in the northeastern, southeastern, and western regions of the Ke'eryin ore field, offering insights into differential uplift/denudation. The integration of regional tectonic evolution, apatite fission track age data, and thermal modelling results reveals that the Ke'eryin ore field has underwent two primary phases of rapid cooling after its formation: initially from the Late Jurassic to the Cretaceous, and subsequently from the Early Miocene to the present. The initial rapid cooling phase is mainly attributed to the LhasaQiangtang collision, whereas the subsequent phase is connected to significant fault activity and regional river incision due to the India-Asia continental collision. Apatite fission track age data and thermal modelling results indicate that differential uplift/denudation between the eastern and western Ke'eryin ore field primarily took place during the Late Miocene of the Cenozoic. The development of the thrust fault, which has been constrained to have initiated since 12 Ma, has led to the denudation of lithium deposits in the hanging wall (the western and northern parts of the Ke'eryin ore field), whereas those in the footwall (the eastern part) remain relatively well preserved. Based on these characteristics, this study recommends focusing exploration efforts for pegmatite-type lithium resources in the footwall regions, particularly in exploration gaps that are away from river valleys between large and super-large deposits. Additionally, in the entire Songpan-Garze fold belt, there is significant pegmatite-type lithium exploration potential in the high elevation, arid, and less topographically relieved western regions