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

中安第斯山脉南部的同造山新近纪前陆盆地(S 32-35度)提供了一个敏感但约束较差的记录，记录了这个典型的会聚大陆弧系的构造、岩浆作用和造山折返的时空格局。盆地演化受纳斯卡板块分段的强烈影响：在33度S以北，俯冲板块处于俯冲水平，产生与基底有关的厚皮收缩变形、破碎的前陆和稀疏的岩浆活动；在33度S以南，俯冲板块达到正常的俯冲角度，具有幕式岩浆活动、薄皮构造变形和叠置背靠式盆地的发育。将边缘分成平坦的、过渡的和正常的板片段，在弧岩浆作用、构造变形和盆地发展方面产生了纵向变化，这为研究造山折返和盆地演化的沿走向对比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(S 32-35度)新近纪造山折返作用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格局的关系。具体地说，这项研究将研究同造山前陆盆地的时空分布与板片倾角的变化、造山折返模式和速率沿走向的变化以及先前存在的基底构造对造山折返和盆地发育的控制。一项系统的野外研究计划将把碎屑锆石(U-Pb、Hf、(U-Th)/He)的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，以限制新近纪同造山盆地的时间、幕式、物源、沉积结构和沉降速率。安第斯山脉中南部提供了一个理想的实验室，以检验造山折返速度和大小与相邻盆地发展的时空格局之间的动态联系。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抬升的幅度和速度、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在一起，研究沿三个安第斯山脉横断面(S 32-35度)的新近系地壳动力学。来自威斯康星大学、Eau Claire大学和圣地亚哥州立大学的学生和教职员工将在实地和实验室工作以及联合出版物方面与这些组织密切合作。在阿根廷的研究将是威斯康星大学Eau Claire大学跨学科体验式学习活动的组成部分。该项目得到了构造计划和国际与国际事务综合办公室的支持。

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.