Cenozoic thermal-tectonic evolution of Sundaland: Constraints from low-temperature thermochronology

Subduction of the Pacific and Indian-Australian Plates, regional transpression, lateral block extrusion, and structural inversion have all interacted to affect the crustal deformation and enhance local and regional exhumation across Sundaland during the Cenozoic. The Cenozoic tectonics of Sundaland has been studied using various thermochronometric techniques over the past three decades. In this study, we provide new apatite (U-Th)/He data in Vietnam and Borneo and compile published low-temperature thermochronologic ages to estimate temporal and spatial variation of exhumation rates in the Indochina Peninsula and Borneo. Our findings indicate that Early Cenozoic regional transpression controlled the Paleogene widespread exhumation from Peninsular Malaysia, through the Gulf of Thailand, to central Thailand and into Yunnan due to early oblique collision. Local rapid exhumation of lower crustal units, young granite plutons, and hilly terranes occurred during the Oligocene to Miocene driven by rifting, block lateral extrusion, structural inversion, and buoyant doming. Borneo Island experienced diachronous exhumation history likely due to the subduction of Proto-South China Sea, collision between Australia and southeastern Borneo, and dynamic support from the mantle. A synthesis of our (U-Th)/He data, published thermochronologic data, and thermal modeling contribute to revealing the Cenozoic local structural evolution and regional tectono-thermal events across Sundaland and give new insights into the driving dynamic mechanisms.