An orogenic plateau in the southern U.S. Cordillera?

北美西部的山脉通常被统称为北美科迪勒拉山脉，是与海洋板块和大陆板块碰撞有关的古代板块构造系统的极好例子。然而，目前尚不清楚美国南部的科迪勒拉是如何适应这种碰撞框架的。美国南部科迪勒拉的几个特征表明，该地区可能是一个高架高原，类似于今天内华达州大盆地地区的高架高原。目前，对于地壳如何在美国西南部增厚，从而形成这个高原，还没有公认的机制或理论。该项目将测试在亚利桑那州南部地区是否存在一个高架高原和相关的增厚地壳，并确定这样一个高原可能形成的机制。该项目由怀俄明大学的首位NSF研究员领导，包括第一代西班牙裔博士生，并将纳入本科生研究项目。学生将获得实验室和实地方法的经验，包括地质制图。项目参与者还将制作一系列记录该项目的研究活动的短片供公众发布。这个项目的目标是测试在中生代晚期到新生代早期美国南部科迪勒拉是否存在造山带高原“亚利桑那高原”的假设，并限制这种高原可能形成的机制。这项工作的初始阶段将使用中间弧相关火成岩的地球化学指标（例如La/Yb）来确定古地壳厚度。第二阶段将包括对亚利桑那州南部一系列山脉进行新的地质测绘和结构分析，以确定是否存在低角度的“塞维尔式”逆冲断层，是否在区域范围内广泛存在，是否可能使地壳变厚。最近的发现和初步的测绘提供了一个机会，使构造单元在山脉之间相互关联，并组装区域尺度的构造合成截面。本研究的最后阶段将把白垩纪至古近纪沉积岩的构造热史与该地区的变形史联系起来。这项工作通过帮助限制美国西南部科迪勒拉造山带的中生代演化，具有超越区域研究领域的重要意义。该项目由地球科学部的构造学计划和促进竞争研究的建立计划（EPSCoR）共同资助。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The mountain ranges of western North America, often collectively called the North American Cordillera, are excellent examples of ancient plate tectonic systems associated with collisions between oceanic and continental plates. However, it is unclear how the southern U.S. Cordillera fits within this collisional framework. Several features of the southern U.S. Cordillera suggest that the region may have been characterized by an elevated plateau, similar to today's elevated plateau in the Great Basin area of Nevada. At present, there is no accepted mechanism or theory for how the crust may have been thickened in the southwestern U.S. to create this plateau. This project will test whether an elevated plateau and associated thickened crust previously existed in the southern Arizona region and determine the mechanisms by which such a plateau could have been constructed. This project is led by a first-time NSF investigator at the University of Wyoming, includes a first-generation Hispanic Ph.D. student, and will incorporate undergraduate student research projects. Students will gain experience in laboratory and field methods, including geologic mapping. Project participants will also create a series of short-format videos for public release that document research activities of the project.The goal of this project is to test the hypothesis of whether an orogenic plateau, the "Arizonaplano" existed in the southern U.S. Cordillera during the late Mesozoic to early Cenozoic and constrain the mechanisms by which such a plateau could have been constructed. The initial phase of this work will use geochemical indices (e.g., La/Yb) from intermediate arc-related igneous rocks to determine paleo-crustal thickness. The second phase will include new geologic mapping and structural analyses in a series of mountain ranges in southern Arizona to determine whether low-angle, "Sevier-style" thrust faults exist, were regionally extensive, and could have thickened the crust. Recent discoveries and preliminary mapping provides an opportunity to correlate structural units across mountain ranges and assemble regional-scale cross sections for tectonic syntheses. The final phase of this research will link the tectonothermal history of Cretaceous to Paleogene sedimentary rocks to the deformation history of the region. This work has important relevance beyond the regional study area by helping to constrain the Mesozoic evolution of the Cordilleran orogen in the southwestern U.S.This project is jointly funded by the Tectonics program in the division of Earth Sciences and the Established Program to Stimulate Competitive Research (EPSCoR).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.