Exploiting Thermochronology to Quantify Exhumation Histories and Patterns of Uplift Along the Margins of Tibet
Exploiting Thermochronology to Quantify Exhumation Histories and Patterns of Uplift Along the Margins of Tibet
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DOI：
10.3389/feart.2021.688374
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发表时间：
2021-06
期刊：
影响因子：
5.7
通讯作者：
K. Furlong;E. Kirby
中科院分区：
文献类型：
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作者：
K. Furlong;E. Kirby
利用热年代学数据来限制造山过程，利用了造山过程中岩石隆升、挖掘和冷却之间的联系。从概念上讲，快速隆起和相关剥蚀的时期将导致岩石在接近地球表面时冷却。隆升和挖掘之间的联系可能是复杂的，但在实践中，挖掘通常被认为是直接跟踪隆升的。通过热年代学系统重建温度-时间历史提供了一种代理方法，将岩石在向地表挖掘时的冷却与造山作用联系起来。由于热平流、热扰动的传播速率和其他影响冷却行为的过程，在活动造山系统中可能发生的快速掘出速率将是复杂的。随着挖掘速率的增加，这些影响会被放大，在挖掘速率大于~ 0.2-0.3毫米/年（0.2-0.3公里/毫安）的地区，通过恒定地热降温的简单假设会使后续解释产生偏差。在这里，我们通过一套广义模型来探讨挖掘速率和持续时间对所得热历史和表观年龄结果的影响。由此得出的发掘历史对新生代发掘的开始、随后的发掘速度以及龙门山中部主要断裂系统之一的构造历史提供了约束。
The utilization of thermal-chronological data to constrain mountain building processes exploits the links among rock uplift, exhumation, and cooling during orogenesis. Conceptually, periods of rapid uplift and associated denudation will lead to cooling of rocks as they approach Earth’s surface. The linkage between uplift and exhumation can be complex, but in practice exhumation is often assumed to directly track uplift. The reconstruction of temperature-time histories via thermochronologic systems provides a proxy method to relate the cooling of rock as it is exhumed toward the surface to orogenesis. For the rapid exhumation rates that can occur in active orogenic systems the thermal history will be complex as a result of heat advection, rates of propagation of thermal perturbations, and other processes that affect the cooling behavior. These effects become amplified as exhumation rates increase, and in regions experiencing exhumation rates greater than ∼0.2–0.3 mm/yr (0.2–0.3 km/Ma) simple assumptions of cooling through a constant geotherm will bias the subsequent interpretation. Here we explore, through a suite of generalized models, the impact of exhumation rate and duration on the resulting thermal history and apparent age results. We then apply lessons from these simple exhumation systems to data sets from the high-relief ranges along the eastern margin of the Tibetan Plateau to determine exhumation histories constrained by those data. The resulting exhumation histories provide constraints on the onset of Cenozoic exhumation, the subsequent pace of exhumation, and on the tectonic history of one of the major fault systems in the central Longmen Shan.