Duration of the Huangling Dome Activity in the Northern Margin of the South China Continent: Insight From Integration of Zircon (U–Th)/He Dating and Thermal Modeling

Abstract

AbstractThe Huangling dome, which is one of the largest tectonic domes in the South China continent, was formed between the Late Jurassic and Early Cretaceous, when regional compression was eventually replaced by regional extension. This raises an issue about whether the dome was generated by compression, extension or both. This study integrates single‐grain zircon (U–Th)/He (ZHe) dating with thermal modeling to better constrain the formation process of the dome. The measured ZHe ages of samples collected from the dome and adjacent synclines are all younger than the depositional or crystallization ages of the sampled rocks, and the western and eastern dome sides have much older ZHe mean ages than those of the dome and synclines' cores. They make clear the complex interactions between uplift, denudation, and heating processes during dome formation. For simplicity, we developed one‐dimensional heat‐conduction models that cover a wide range of heating and exhumation scenarios (assuming that uplift rate equals denudation rate) within an interval of 152.1–121.4 Ma. These models were solved and searched for the predictions of the measured ages. The best models have a fast decrease in uplift rate with time and a constant heating rate, indicative of an early interval shaping of the dome in a compressional setting.