Collaborative Research: RUI: Orogenic Exhumation and Neogene Foreland Basin Evolution, Central Andes

中安第斯山脉南部（南纬32-35度）的同造山新近纪前陆盆地提供了一个敏感的，但缺乏约束，时空格局的记录，构造，岩浆作用和造山折返在这个经典的收敛大陆弧系统。盆地演化受到纳斯卡板块分段的强烈影响：南纬33度以北，俯冲板片呈近水平状态，产生基底参与的厚皮收缩变形、破碎的前陆和稀疏的岩浆活动;南纬33度以南，俯冲板片达到正常俯冲角度，具有幕式岩浆活动、薄皮构造变形和堆叠背驮式盆地的发育。分割成平坦的，过渡性的和正常的板片段的边缘产生弧岩浆作用，构造变形和盆地的发展，提供了一个理想的实验室，研究对比沿走向模式的造山折返和盆地演化的纵向变化。本研究的主要目的是记录新近纪造山折返的时空格局及其与安第斯山脉中南部（南纬32-35度）的构造变形、地形演化、盆地发育和沉积物散布格局的关系。更具体地说，本研究将探讨同造山前陆盆地的时空分布与板片倾角变化的关系，造山带沿着走向的折返方式和速率的变化，以及先存基底构型对造山带折返和盆地发育的控制。一个系统的实地研究计划将整合碎屑锆石的同位素分析（U-Pb，Hf，（U-Th）/He），并结合地层分析、全岩地球化学和磷灰石（U-Th）/He热年代学来确定时间、事件性、物源，晚第三纪同造山盆地的沉积结构和沉降速率。中安第斯山脉提供了一个理想的实验室，以检查造山剥露的速度和规模与相邻盆地发展的空间和时间模式之间的动态联系。了解这种联系将有助于深入了解盆地地层学的使用，以限制地震活跃区的构造隆起的幅度和速度，经济资源的积累和保存的评估和地球历史的准确重建。该项目与两个国际（阿根廷、智利、法国和美国）多学科区域规模调查紧密结合，研究沿着三个跨安第斯断面（南纬32-35度）的新近纪地壳动力学。来自威斯康星州欧克莱尔大学和圣地亚哥州立大学的学生和教师将在实地和实验室工作以及联合出版物方面与这些小组密切合作。在阿根廷的研究将是威斯康星州欧克莱尔大学跨学科体验式学习活动的组成部分。该项目得到了Tectonics Program和国际综合事务办公室的支持。

Synorogenic Neogene foreland basins of the southern Central Andes (32-35 degrees S) provide a sensitive, but poorly constrained, record of the spatial and temporal patterns of tectonics, magmatism and orogenic exhumation across this classic convergent continental arc system. Basin evolution is strongly influenced by the segmentation of the Nazca plate: North of 33 degrees S, the subducting slab is subhorizontal, producing basement-involved thick-skinned contractional deformation, a broken foreland, and sparse magmatism; south of 33 degrees S, the subducting slab attains a normal subduction angle, with episodic magmatic activity, thin-skinned structural deformation and development of stacked piggy back basins. Segmentation of the margin into flat, transitional and normal slab segments produces longitudinal variations in arc magmatism, structural deformation and basin development that provide an ideal laboratory to examine contrasting along-strike patterns of orogenic exhumation and basin evolution. The primary objective of this investigation is to document the temporal-spatial pattern in Neogene orogenic exhumation and its relation to structural deformation, topographic evolution, basin development and sediment dispersal patterns in the southern Central Andes (32-35 degrees S). More specifically, this investigation will examine the relationship of spatial and temporal distribution of synorogenic foreland basins to variation in slab dip, the variation in pattern and rate of orogenic exhumation along strike, and the control of pre-existing basement configuration on orogenic exhumation and basin development. A systematic field-based research program will integrate isotopic analyses of detrital zircon (U-Pb, Hf, (U-Th)/He) with stratigraphic analysis, whole rock geochemistry and apatite (U-Th)/He thermochronology to constrain the timing, episodicity, provenance, depositional architecture and subsidence rate of Neogene synorogenic basins.The south-central Andes Mountains provides an ideal laboratory to examine the dynamic linkage between the rate and magnitude of orogenic exhumation and the spatial and temporal pattern of adjacent basin development. Understanding this linkage will provide insight into the use of basinal stratigraphy to constrain the magnitude and rate of tectonic uplift in seismically active regions, the evaluation of the accumulation and preservation of economic resources and the accurate reconstruction of earth history. The project is tightly integrated with two international (Argentina, Chile, France, and United States) multidisciplinary regional-scale investigations studying Neogene crustal dynamics along three cross-Andean transects (32-35 degrees S). Students and faculty from University of Wisconsin Eau Claire and San Diego State University will collaborate closely with these groups in field and laboratory work and joint publications. Research in Argentina will be integral in interdisciplinary experiential learning activities at the University of Wisconsin Eau Claire. The project is supported by the Tectonics Program and the Office of International & Integrative Affairs.