Zircon (U-Th)/He thermochronology and thermal evolution of the Tarim Basin, Western China

Abstract

• Single-grain ZHe ages of the clastic rocks in Tarim Basin are dispersed with 94 Ma-995 Ma. • The forward and inverse modeling reveals four cooling events since the Neoproterozoic. • The samples experienced several thermal events with the highest temperature of 160–180 ℃. Thermal history reconstruction of the deep and ancient strata (Pre-Silurian) in the Tarim Basin is always difficult due to the lack of effective paleo-thermal indicators. This study provides a new strategy for thermal history reconstruction of the Tarim Basin with the zircon (U-Th)/He thermochronology. The obvious dispersion of the single-grain zircon (U-Th)/He ages for all the clastic rocks in the Tarim Basin reflects the complex and protracted thermal histories. The combination of forward and inverse modeling revealed that the Neoproterozoic rocks from the Kalpin and Bachu Uplifts experienced four rapid cooling events beginning in the Late Ordovician, Late Carboniferous, Late Triassic and Early Miocene, while the Silurian rocks in the eastern Tarim Basin just experienced the Late Carboniferous and Late Cretaceous cooling events. In addition, these rocks experienced several thermal events with the highest temperature of 160–180 °C (a precision of 5–10 °C). The unique thermal histories in the Tabei Uplift and Shunbei area was suitable for the crude oil preservation. This study not only promotes the application of the zircon (U-Th)/He thermochronology in sedimentary basins but also clarify the thermal evolution process of the ancient strata in the Tarim Basin, which plays an important role in determining the deeper source rocks maturation phase and hydrocarbon occurrence state.