The Thermal-Mechanical Evolution of Middle Hsuehshan Range, Taiwan: Using Numerical Modeling and Zircon Fission Track Ages
Date Issued
2014
Date
2014
Author(s)
Shyu, Chase Jhih-Huang
Abstract
Located in northern Taiwan, the Hsuehshan Range is the second largest range and has its own special lithology, structural and thermochronological features with high exhumation rate. In most previous studies of forward modeling of Taiwan mountain building, however, the existence of the Hsuehshan Range was ignored. Its thermal-mechanical evolution should be investigated in addition to the evolution of Taiwan mountain range. Moreover, in the aspect of thermochronology, most of the previous studies that discussed the age-elevation relationship do not consider the effect of cooling rate on closure temperature. In this study, we simulate this effect numerically and discuss local exhumation rate in middle Hsuehshan Range using six new zircon fission track ages together with previously published data via the 1-D thermal advection-diffusion model. Furthermore, for the purpose of applying the cooling-rate-closure-temperature relationship to 2-D model and testing the assumption of the initial tectonic framework of the Hsuehshan Range, we simulate the formation of the Hsuehshan Range by introducing the 2-D thermal-mechanical model and compared the modeling predictions with real geochemical data. In the 1-D model, we found a unique phenomenon that we call "Wide-zoned Closure" in the initial stage of orogen. The Wide-zoned Closure signature will induce a spatially vertical zone with similar thermochronological ages. As a result, a vertical profile of thermal age would show a slowly decreasing age trend. By regulating parameters reasonably, the best-fitting 1-D model to the thermochronological data in middle Hsuehshan Range suggests that this area started to exhume with a rate of 5.0 km/Myr around 3.1 Ma. On the other hand, the 2-D modeling results imply that the initial lithology setting would influence the deformation behavior of orogen and result in different distribution of thermo-chronological ages. Additionally, the results suggest that the Hsuehshan Range has inherited influence from the Hsuehshan Basin and that the eastern part of the Hsuehshan Range was an active deformation zone in initial stage of orogen.
Subjects
台灣
雪山山脈
熱年代-高度關係
鋯石核飛跡
寬帶癒合
數值模型
Type
thesis
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