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

SGER：同生沉积物的探索性热年代学作为限制山地带长期侵蚀历史的新工具

• 批准号: 0629331
• 负责人: Ben van der Pluijm
• 金额: --
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-06-01 至 2007-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0629331&HistoricalAwards=false
• 关键词: SGER; Exploratory; Thermochronology; Synorogenic; Deposits

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.

山带的侵蚀是构造力和气候力复杂相互作用的结果。为了评估这些作用力如何相互作用以控制造山带侵蚀，有必要建立山带长期侵蚀历史的详细记录。同造山带沉积物中保存的热年代学年龄反映了源地挖掘过程中的冷却作用，因此碎屑研究是建立山区侵蚀记录的有力工具。大多数研究使用单一的温度计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，它们可能来自一个山带内的不同地区，这些地区可能以不同的速度侵蚀。这项探索性的、面向实地的研究侧重于开发一种替代方法，该方法使用同造山砾岩矿床的成对热年代学年龄。由于单个鹅卵石中的所有颗粒具有共同的热历史，配对定年可以揭示样品在挖掘过程中所采取的详细时间-温度路径。这些热历史被用来约束源地的侵蚀历史。这种方法正在西班牙比利牛斯山脉的一小块地区进行测试，在那里，西斯山砾岩体保存了2000万年的同造山沉积历史。通过测量地层剖面中几个样品的冷却历史，可以推测在造山带的整个生命周期中，山带的侵蚀速率是如何演变的。为了研究侵蚀速率的变化如何与断层脉冲相关联，还将热年代学结果与断层泥定年获得的局部逆冲时间的新估计进行了比较。这项研究为加强地球科学家对山脉长期演化的理解带来了巨大的希望。现代构造学的一个主要问题是构造力和气候力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必需的详细和长期的侵蚀记录。一旦建立，这种方法可能被广泛应用于揭示世界范围内造山带的侵蚀历史，包括古代环境中所有山带的遗迹都是被侵蚀的残留物。此外，它将支持一个早期职业生涯的博士后科学家。