Cenozoic Migration of Topography in the North American Cordillera Recorded in Coupled Basin-Detachment Systems

该课题组正在对北部盆地、山脉和毗邻的落基山脉内的盆地-变质核杂岩对进行古海拔测量研究，以重建该地区的新生代高程史，并检验伸展动力的相互竞争的假说。基于这些假设的构造模型可以广泛地与三种相互竞争的地表抬升和伸展机制相关联：(1)黄石热点热柱在岩石圈底部的撞击，(2)地幔岩石圈的拆离，(3)重力势能梯度驱动的浮力相关流动。这些模型中的每一个都预测了不同的和可测试的地形响应。用稳定同位素方法重建了蒙大拿州、内华达州和犹他州的变质核杂岩和邻近盆地的新生代古海拔历史。这项古高度学研究将提供一套独特的约束条件，结合地球物理和地质数据集，应能更好地理解北部盆地和山脉以及北美科迪拉拉新生代伸展背后的驱动力。这一研究项目建立在之前对美国西部变质核杂岩和山间盆地的古海拔研究的基础上，这些研究表明，北美西部的地形发展具有时空变化的历史，地表隆起随着时间的推移向南迁移。地球上的所有大陆都有大山脉。然而，这些山脉是如何生长的，仍然是地球科学中比较难以捉摸的问题之一。了解山脉的地形历史对于评估不同的构造模型以及确定山脉的增长如何影响气候变化至关重要。对于新生代(地球历史的最后6500万年)来说尤其如此，因为有人提出，喜马拉雅/西藏和北美西部科迪勒拉等新生代大山脉的建设改变了地球的气候。这项研究利用稳定同位素古高度计研究了美国西部科迪勒拉新生代的地形和气候历史，并对已提出的该地区的构造模型进行了评估。它将提供关于美国西部山脉如何形成的新见解，以及关于山脉增长和气候之间的联系和反馈的关键信息。

This research group is conducting a paleoaltimetry study of basin-metamorphic core complex pairs within the northern Basin and Range and contiguous Rocky Mountains in order to reconstruct the Cenozoic elevational history of this region and to test competing hypotheses of the driving forces for extension. Tectonic models based on these hypotheses can be broadly associated with three competing surface uplift and extension mechanisms: (1) impingement of the Yellowstone hot spot plume at the base of the lithosphere, (2) delamination of mantle lithosphere, and (3) buoyancy-related flow driven by gradients in gravitational potential energy. Each of these models predicts distinct and testable topographic responses. Cenozoic paleoelevation history is being reconstructed for metamorphic core complexes and adjacent basins in Montana, Nevada, and Utah using stable isotope methods. This paleoaltimetry study will provide a unique set of constraints, which combined with geophysical and geologic data sets, should yield a better understanding of the driving forces behind Cenozoic extension in the northern Basin and Range and the North American Cordillera. This research project builds upon previous paleoelevation studies of metamorphic core complexes and intermontane basins in the western United States that suggest a history of spatially and temporally varying topographic development of western North America with surface uplift migrating southward with time.Large mountain ranges are found on all the Earth's continents. How these mountain ranges grow, however, remains one of the more elusive questions in earth sciences. Understanding the topographic history of mountain ranges is critical for evaluating different tectonic models as well as determining how the growth of mountains affects climate change. This is particularly true for the Cenozoic (last 65 million years of Earth's history) because it has been proposed that the construction of the large Cenozoic mountain belts, such as the Himalaya/Tibet and western North America Cordillera, have altered the Earth's climate. This study examines the Cenozoic topographic and climate history of the western U.S. Cordillera using stable isotope paleoaltimetry and evaluates the tectonic models that have been proposed for this region. It will provide new insights regarding how the American western mountain ranges formed as well as critical information on the links and feed-backs between growth of mountain ranges and climate.