EAPSI:Determining the characteristics of deformation and role of fluids along deep faults associated with mountain belt formation in South Korea

在造山带的形成过程中，两个构造板块发生碰撞，与碰撞相关的压缩和缩短导致岩石片相互堆叠。这就形成了一系列断层和褶皱，称为褶皱-冲断带。最低的断层（基底拆离断层）允许其上方的一切物质移动，在褶皱冲断带的演化中起着重要作用，但很少发现其暴露在地表。韩国的Okcheon带是在大约2.5亿年前的构造碰撞中形成的。它有一个暴露良好的基底拆离带，这为直接研究它提供了一个难得的机会。除了野外测绘外，还将收集野外数据和岩石样品，以观察沿着基底拆离带发生的大规模和小规模变形和流体流动。这项研究将与延世大学的Sanghoon Kwon博士合作进行，Sanghoon Kwon博士是二叠纪-三叠纪碰撞构造地质学方面的著名专家。这一合作将提供与山脉带形成有关的沿着基底沉积物发生的过程的第一个直接证据，并将使人们进一步了解山脉形成的过程。褶皱冲断带是造山带的重要组成部分。在现有的模型中，基底滑脱在FTB的演化中起着关键作用，但它很少暴露在地表。韩国玉川带的最低构造断层是碰撞二叠纪-三叠纪造山带的暴露良好的基底滑脱，它将京畿和Yeongnam地块连接在一起。本项目将与韩国首尔延世大学的Sanghoon Kwon博士合作研究该滑脱。为了记录观测结果和收集数据，将对沿着和横跨滑脱带的一系列结构断面进行研究。将沿着断面采集手工样品，用于断层岩（如糜棱岩、碎裂岩）中变形结构的显微结构分析。为了确定流体沿着的作用，将沿断面沿着采集矿脉的滑脱样品，以进行稳定同位素和流体包裹体分析。除了这些微观和化学分析，变形结构的介观分析将进行，以确定运动学，力学和流体在基底滑脱变形区的作用。这将导致更全面地了解滑脱流变学对褶皱冲断带的几何形状和演化的影响。该奖项是东亚和太平洋夏季研究所计划下的一个奖项，支持美国研究生的夏季研究，由NSF和韩国国家研究基金会共同资助。

During the formation of a mountain belt (orogeny), two tectonic plates collide and the compression and shortening associated with this collision result in slices of rocks stacking up on one another. This forms a series of faults and folds, known as a fold-thrust belt. The lowest fault (basal detachment), which allows everything above it to move, plays an important role in the evolution of the fold-thrust belt but is seldom found exposed at the surface. The Okcheon Belt in South Korea formed during a tectonic collision ~250 million years ago. It has a well-exposed basal detachment providing a rare opportunity to directly study it. Field data and rock samples will be gathered, in addition to field mapping, to look at the large scale and small scale deformation and flow of fluids occurring along the basal detachment. This research will be conducted in collaboration with Dr. Sanghoon Kwon at Yonsei University, a noted expert on the structural geology of the Permo-Triassic Collision. This collaboration will provide the first direct evidence of the processes occurring along basal detachments associated with the formation of mountain belts and will give further understanding of the processes by which mountains form. A fold-thrust belt (FTB) is an important component of any orogenic belt. In existing models, the basal decollement plays a key role in the evolution of the FTB, but it is rarely exposed at the surface. The structurally lowest fault of the Okcheon Belt in South Korea is the well-exposed basal decollement of the collisional Permo-Triassic orogeny, which brought together the Gyeonggi and Yeongnam Massifs .This project will examine this decollement in collaboration with Dr. Sanghoon Kwon at Yonsei University in Seoul, South Korea. To record observations and collect data, a series of structural transects will be studied both along and across the decollement zone. Hand samples will be taken along the transects to be used for microstructural analysis of deformation structures in the fault rocks (e.g. mylonites, cataclasites). To determine the role of fluids along the decollement samples of veins will be collected along the transects to conduct stable isotope and fluid inclusion analyses. In addition to these microscopic and chemical analyses, mesoscopic analysis of deformation structures will be conducted to determine the kinematics, mechanics, and role of fluids in a basal decollement deformation zone. This will lead to a more complete understanding of the effects of decollement rheology on the geometry and evolution of fold-thrust belts.This award under the East Asia and Pacific Summer Institutes program supports summer research by a U.S. graduate student and is jointly funded by NSF and the National Research Foundation of Korea.