SGER: Exploratory Thermochronology of Synorogenic Deposits as a New Tool to Constrain the Long-Term Erosional History of Mountain Belts

山脉地带的侵蚀是构造和气候力量复杂相互作用的结果。为了评估这些力量如何相互作用以控制造山带的侵蚀，必须详细记录山带的长期侵蚀历史。同造山沉积中保存的热年代学年龄反映了源岩折返过程中的冷却，因此碎屑研究是建立山脉侵蚀记录的有力工具。大多数研究使用单一的温度计时器来评估保存在谷物种群中的冷却历史。然而，沉积物或沉积岩中的单个颗粒不一定具有共同的热历史，很可能来自山带内的不同地区，这些地区可能以不同的速度侵蚀。这项探索性的、以野外为导向的研究集中于开发一种替代方法，该方法使用来自同造山砾岩沉积的成对热年代学年龄。由于单个鹅卵石中的所有颗粒都有共同的热历史，配对测年揭示了样本在挖掘过程中采取的详细的时间-温度路径。这些热历史被用来约束源岩的侵蚀历史。这种方法正在西班牙比利牛斯山的一小片地区进行测试，那里的塞斯山脉砾岩机构保存了2000万年的同造山沉积历史。整个地层剖面的几个样品的冷却历史正在被测量，以假设造山带的侵蚀速度在造山带的整个生命周期中可能是如何演变的。为了研究侵蚀速率的变化如何与断层脉冲有关，还将热年代学结果与通过断层泥测年获得的局部冲断时间的新估计进行了比较。这项研究对加强地球科学家对山脉长期演化的理解具有重要的前景。当代构造学中的一个主要问题是，构造和气候力量如何相互作用来控制山带的形状和结构。这项探索性研究正在寻找新的工具，以获得解决这一问题所需的详细和长期的侵蚀记录。一旦建立，这种方法可能会被广泛应用于揭示世界各地造山带的侵蚀史，包括古代环境，在那里，山带的所有遗迹都是它被侵蚀的残留物。此外，它还将支持一名早期职业博士后科学家。

Erosion in mountain belts results from the complex interplay between tectonic and climatic forces. In order to assess how these forces interact to control orogenic erosion, it is essential to establish a detailed record of the long-term erosional history of mountain belts. The thermochronologic ages preserved in syn-orogenic sediments reflect cooling during exhumation of the source terrane and therefore detrital studies represent a powerful tool with which to establish a record of mountain erosion. Most investigations utilize a single thermochronometer to assess the cooling history preserved in a population of grains. However, the individual grains in a sediment or sedimentary rock do not necessarily share a common thermal history and were likely derived from different areas within a mountain belt that may erode at distinct rates. This exploratory, field-oriented study is focused on developing an alternative approach that uses paired thermochronologic ages from syn-orogenic conglomerate deposits. Because all grains in a single cobble share a common thermal history, paired dating reveals the detailed time-temperature path taken by the sample during exhumation. These thermal histories are used to constrain the erosional history of the source terrane. This approach is being tested in a small area of the Spanish Pyrenees, where the Sierra de Sis conglomerate body preserves a 20 million year history of syn-orogenic deposition. The cooling histories from several samples throughout the stratigraphic section are being measured to hypothesize how the rate of erosion in the mountain belt may have evolved throughout the lifespan of the orogen. To investigate how variations in the erosion rate may be associated with pulses of faulting, the thermochronologic results is also compared with new estimates on the timing of local thrusts obtained from the dating of fault gouge. This research holds significant promise for enhancing earth scientists' understanding of the long-term evolution of mountains. A major question in contemporary tectonics is how tectonic and climatic forces interact to control the shape and structure of mountain belts. This exploratory study is seeking new tools to obtain the detailed and long-term records of erosion necessary to address this problem. Once established, this approach may be widely applied to reveal the erosional history of orogenic belts worldwide, including ancient settings where all that remains of a mountain belt are its eroded remnants. In addition, it will support an early career post-doctoral scientist.