Perturbation of isotherms below topography: constraints from tunnel transects through the Alps

地形以下等温线的扰动：穿过阿尔卑斯山的隧道横断面的约束

• 批准号: 5450720
• 负责人: Professor Dr. Wolfgang Frisch
• 金额: --
• 依托单位: Fachgebiet Geodynamik der Polargebiete
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2005
• 资助国家: 德国
• 起止时间: 2004-12-31 至 2009-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/5450720?language=en
• 关键词: Perturbation; isotherms; below; topography; constraints

... This study, in contrast, aims to directly measure the position of isotherms below topographic relief under a given framework of denudation rate, topographic wavelengths, relief amplitued, and geothermal gradient. Our study areas are three tunnel transects through the Central and Western Alps; the Gotthard, Lötschberg, and Mont Blanc tunnels. All three profiles are situated in rapidly exhuming areas with relief between 1500 and 2800 m and topographic wavelength of about 10 km, thus representing typical geomorphic features of active orogens. Samples from the tunnel profiles and their corresponding surface profile will be dated by zircon fission track, apatite fission track, and apatite (U-Th)/He analysis. Distributions of these ages will yield two-dimensional profiles showing the positions of isotherms below topography. The two-dimensional profiles may at least partly be correlated to three-dimensional images, show the sensitivity of the different thermochronologic dating techniques to the perturbation effect, and give a measure of the perturbation-induced overestimation of exhumation rates inherent to the different dating techniques. The results will be used to test existing models and to provide benchmarks for future model concepts.

...相反，本研究的目的是在给定的剥蚀率、地形波长、起伏幅度和地热梯度的框架下，直接测量地形起伏以下等温线的位置。我们的研究区域是通过阿尔卑斯山中部和西部的三个隧道断面;圣哥达，Lötschberg和勃朗峰隧道。这三个剖面都位于快速折返区，地形起伏在1500 - 2800 m之间，地形波长约为10 km，代表了典型的活动造山带地貌特征。隧道剖面及其相应表面剖面的样品将通过锆石裂变径迹、磷灰石裂变径迹和磷灰石（U-Th）/He分析确定年代。这些年龄的分布将产生二维剖面图，显示地形下等温线的位置。二维剖面至少可以部分地与三维图像相关，显示不同热年代学测年技术对扰动效应的敏感性，并给出不同测年技术固有的扰动引起的折返速率高估的度量。结果将用于测试现有模型，并为未来的模型概念提供基准。