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

在山带形成过程中（造山运动），两个构造板块碰撞，与此碰撞相关的压缩和缩短导致岩石片相互堆积。这形成了一系列的断层和褶皱，被称为褶皱冲断带。最低的断裂（基底滑脱）在褶皱冲断带的演化过程中起着重要作用，但很少在地表暴露出来。韩国的沃川带形成于2.5亿年前的一次构造碰撞中。它有一个暴露良好的基底脱离，为直接研究它提供了难得的机会。除了实地测绘外，还将收集现场数据和岩石样本，以观察沿基底剥离发生的大尺度和小尺度变形和流体流动。此次研究将与二叠纪-三叠纪碰撞构造地质学专家、延世大学的权相勋博士共同进行。这项合作将提供第一个直接证据，证明与山带形成有关的基底分离过程，并将进一步了解山脉形成的过程。褶皱冲断带是任何造山带的重要组成部分。在现有的模型中，基底脱落在FTB的演化中起着关键作用，但很少在地表暴露出来。韩国沃川带构造最低的断裂是二叠纪-三叠纪碰撞造山运动中暴露良好的基底滑脱，将京畿地块和岭南地块聚集在一起。该项目将与韩国首尔延世大学的Sanghoon Kwon博士合作，研究这种脱落。为了记录观测结果和收集数据，将沿滑脱带和整个滑脱带研究一系列的结构样带。将沿着样带采集手样，用于断层岩石（如糜棱岩、碎裂岩）变形结构的微观结构分析。为了确定流体在滑脱过程中的作用，将沿着样带收集矿脉样本，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外，还将进行变形结构的细观分析，以确定运动学、力学和流体在基底脱落变形区的作用。这将使我们更全面地了解滑脱流变学对褶皱冲断带几何形态和演化的影响。该奖项是由美国国家科学基金会（NSF）和韩国国立科学研究财团共同资助的东亚太平洋暑期研究所项目，旨在支持美国研究生的暑期研究。

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.