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

中安第斯山脉南部（32-35°S）的同造性新近纪前陆盆地提供了一个敏感的、但约束较差的记录，记录了这个经典的辐合大陆弧体系的构造、岩浆活动和造山活动的时空格局。盆地演化受纳斯卡板块分割的强烈影响：在南纬33度以北，俯冲板块为亚水平，形成基底型厚皮收缩变形，前陆破碎，岩浆活动稀疏；在33°S以南，俯冲板块达到正常俯冲角，岩浆活动幕式，薄皮构造变形，发育叠合型猪背盆地。将边缘划分为平坦、过渡和正常的板块，产生了弧岩浆作用、构造变形和盆地发育的纵向变化，为研究造山掘出和盆地演化的沿走向模式提供了理想的实验室。本研究的主要目的是记录中安第斯山脉南部（32-35°S）新近系造山发掘的时空格局及其与构造变形、地形演化、盆地发育和沉积物扩散模式的关系。具体而言，本研究将探讨同造前陆盆地的时空分布与板块倾角变化、造山掘出模式和速度沿走向变化的关系，以及原有基底构造对造山掘出和盆地发育的控制作用。系统的野外研究计划将碎屑锆石（U-Pb、Hf、(U-Th)/He）同位素分析与地层分析、全岩地球化学和磷灰石(U-Th)/He热年代学相结合，以约束新近系同造盆地的时间、幕式、物源、沉积结构和沉降速率。安第斯山脉中南部为研究造山带挖掘的速度和规模与邻近盆地发展的时空格局之间的动态联系提供了一个理想的实验室。了解这种联系将有助于深入了解利用盆地地层学来限制地震活动区构造隆升的幅度和速率，评估经济资源的积累和保存以及准确重建地球历史。该项目与两个国际（阿根廷、智利、法国和美国）多学科区域尺度调查紧密结合，研究沿三个跨安第斯横断面（32-35°S）的新近纪地壳动力学。威斯康星大学欧克莱尔分校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。在阿根廷的研究将成为威斯康星大学欧克莱尔分校跨学科体验式学习活动的一部分。该项目得到了构造学计划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.