Collaborative Research: Towards a Quaternary Spatial and Temporal Deformation History at the Central Andean Thrust Front

这项多学科研究旨在测量阿根廷中部安第斯冲断前缘的变形速率，以便：(1)更好地了解薄皮Precordilleran构造带和厚皮Pampean构造带相交处的变形运动学和几何形状；(2)评估该地区盲目推力对门多萨和圣胡安等附近城市等人口中心构成的风险。通过将地质数据（地震线、年代地层、构造剖面）与地貌数据（变形和年代的阶地、风隙、排水模式）相结合，美国研究小组与阿根廷研究人员合作，将转化逆冲断层的滑动速率、逆冲断层上盘和逆冲背斜的隆升速率，并将上盘背斜分支对单个构造的旋转速率转化为完整的时空变形史。五个构造- Barrancas背斜，El Borbollon背斜，Las Penas逆冲断层，Montecito背斜和Cerro Salinas逆冲断层-是地震解释，地貌测绘，宇宙成因定年和排水分析的目标。这项研究将解决构造和地震的危害。研究区位于薄皮东向Precordillera构造域和厚皮西向sierra Pampeanas构造域的交汇处。导致缩短转移到安第斯板块内部的条件，以及同时驱动厚皮和薄皮变形的条件，人们知之甚少。时间和空间约束的变形历史对于回答以下问题至关重要：哪些结构滑动最快；变形历史是均匀的，还是速率是暂时变化的？如果费率是可变的，相邻结构之间或属于不同结构省的结构之间的关系是什么？该项目将记录安第斯前陆的三个隐伏逆冲构造。盲目逆冲断层对门多萨-圣胡安走廊以及世界其他地区构成了重大威胁。这种类型的断层在地震危险分析中特别有趣，因为有时微妙的地貌表达使它们难以识别，特别是在被城市化改变的地区。该地区提供了一个机会，可以研究与不同发展阶段的盲目冲断相关的地貌变化，以及可能表明以前未检测到的变形的排水网络的区域变化。

This multidisciplinary research aims to measure deformation rates at the central Andean thrust front in Argentina in order to (1) better understand the kinematics and geometry of deformation at the intersection of the thin skinned Precordilleran and thick-skinned Pampean structural zones; and (2) assess the risk posed by blind-thrusts in this region for population centers such as the nearby cities of Mendoza and San Juan. By combining geologic data (seismic lines, dated stratigraphy, structural cross-sections) with geomorphic data (deformed and dated terraces and wind gaps, drainage patterns), the U.S. research team in collaboration with Argentine researchers will translate slip rates on thrust faults, uplift rates in the hanging wall of thrusts and blind-thrust anticlines, and rotation rates on the limbs of hanging wall anticlines on individual structures into an integrated spatial and temporal deformation history. Five structures - the Barrancas anticline, El Borbollon anticline, Las Penas thrust fault, Montecito anticline and Cerro Salinas thrust - are targeted for seismic interpretation, geomorphic mapping, cosmogenic dating, and drainage analysis.This study will address both tectonics and seismic hazards. The study region lies at the intersection between the thin-skinned, east-vergent Precordillera and the west-vergent, thick-skinned Sierras Pampeanas tectonic domains. The conditions that have led to the transferal of shortening far into the interior of the Andean plate and that simultaneously drive both thick- and thin-skinned deformation are poorly understood. A temporally and spatially constrained deformation history is of critical importance for answering questions such as: which structures are slipping fastest; is the deformation history uniform, or are rates temporally variable; if rates are variable, what is the relationship between adjacent structures, or between structures belonging to different structural provinces? The project will document three blind thrust structures in the Andean foreland. Blind-thrust faults pose a significant risk to the Mendoza-San Juan corridor as well as other parts of the world. This type of fault is of particular interest in seismic hazard analysis because the sometimes subtle geomorphic expression makes them difficult to identify, especially in areas that have been altered by urbanization. This region presents an opportunity to investigate changes in geomorphology associated with blind-thrusts in different stages of development, as well as regional changes in the drainage network which might indicate previously undetected deformation.