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

合作研究：了解安第斯山脉中部逆冲锋的第四纪时空变形历史

• 批准号: 0711530
• 负责人: Benjamin Brooks
• 金额: $ 11.44万
• 依托单位: University of Hawaii
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-03-01 至 2012-02-29
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0711530&HistoricalAwards=false
• 关键词: Collaborative; Research; Towards; Quaternary; Spatial

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.

这项多学科研究旨在测量阿根廷安第斯山脉中部逆冲断层前缘的变形速率，以便（1）更好地了解薄皮前心和厚皮帕米尔构造带交汇处变形的运动学和几何学;（2）评估该地区盲冲断层对人口中心（如附近的门多萨和圣胡安）造成的风险。通过结合地质数据（地震测线、年代地层学、结构剖面）和地貌数据（变形和过时的阶地和风隙，排水模式），美国研究小组与阿根廷研究人员合作，将转换逆冲断层的滑动速率，逆冲断层上盘和盲冲背斜的抬升速率，和各构造上盘背斜翼部的旋转速率，综合成一个完整的时空变形史。五个构造-巴兰卡斯背斜、埃尔博尔博隆背斜、拉斯佩纳斯逆冲断层、蒙特西托背斜和塞罗萨利纳斯逆冲断层-是地震解释、地貌测绘、宇宙成因年代测定和排水分析的目标。这项研究将涉及构造和地震灾害。该研究区位于薄皮，东向的前Cordillera和西向，厚皮的Sierras Pampeanas构造域之间的交叉点。导致安第斯板块内部缩短的条件以及同时驱动厚皮和薄皮变形的条件知之甚少。一个时间和空间约束的变形历史是至关重要的回答问题，如：结构滑动最快;是变形历史均匀，或率随时间变化;如果率是可变的，是什么关系相邻的结构，或属于不同的结构省之间的结构？该项目将记录安第斯前陆的三个隐蔽逆冲构造。盲冲断层对门多萨-圣胡安走廊以及世界其他地区构成重大风险。这种类型的断层在地震危险性分析中特别有意义，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，调查与盲冲在不同的发展阶段，以及区域变化的排水网络，这可能表明以前未被发现的变形的地貌变化。