Landscape Sensitivity to Changing Climate: Plio-Pleistocene Erosion and Sedimentation in SE Arizona

景观对气候变化的敏感性：亚利桑那州东南部的上新世-更新世侵蚀和沉积arjun Heimsath， Arizona State university -1124460[摘要]亚利桑那州东南部沉积盆地水平的残余物是突出而引人注目的沉积物，因此从20世纪初到现在，它们一直吸引着地质学家的注意。尽管大量的描述工作捕捉到它们的视觉显著性，但对这些矿床的年龄或地质起源却几乎没有共识。虽然形成这些地貌的沉积物有明显的源区，可以追踪和绘制，但构造和气候力量的潜在组合，使这些沉积物被遗弃，远不清楚，也没有得到很好的研究。推断出的松散相关盆地高地的年龄范围为~2万年至1.0-2.2 Ma，更多的是基于推测，而不是定量的地质年代学。该项目将为这些盆地何时充满沉积物的最后阶段以及盆地随后被区域侵蚀事件切割和解剖的时间建立一个绝对的时间表。建立这样一个时间表需要应用和发展宇宙核素方法，这将扩大其时间范围，并测试多种稳定核素和放射性核素的创新使用。采样策略将覆盖亚利桑那州东南部广泛的沉积盆地水平，并将量化沉积物的年龄和源区侵蚀率。由于未变形的盆地高地面和下垫盆地填充物可以追溯到该地区活跃的构造强迫停止的时间，因此表面的侵蚀很可能是由气候强迫驱动的。牢固地建立这些特征的年表，以及源区的古侵蚀率，因此有助于在构造和气候力量如何塑造地球之间建立一座桥梁。年代的表面。这些表面在亚利桑那州东南部的视觉上引人注目的性质确保了人们对它们的起源以及它们如何能够洞察构造和气候力量的广泛兴趣。通过建立如此广泛研究和几乎没有日期的景观的地质年代学，我们将扩大这个项目的知识范围，远远超出假设的检验。具体来说，天空岛联盟将帮助我们协调如何理解过去气候对景观的影响，从而更好地预测本研究中生态敏感地区的未来变化。我们正在研究的每一个沉积层都起源于现在特有物种和空间隔离生态系统的发源地。因此，在定量地了解这些景观在不同气候条件下如何变化方面存在跨学科的兴趣。此外，由美国国家科学基金会资助的杰梅兹河临界区天文台（CZO），由亚利桑那大学的同事管理，在我们的一些实地地点附近有实地地点。我们正在与他们协调领域的努力和约会策略，从而确保具有智力重叠但项目目标非常不同的项目之间的协同作用。我们将与双方协调本科生和K-12学生的培训和外展，从而进一步扩大项目的范围。该项目与伯克利地质年代学中心之间的合作研究将有助于开发亚利桑那州立大学的设施，并培养研究生。最后，本项目所使用的实地考察活动有助于开发我校本科和研究生课程的实地组成部分和课程。

Landscape sensitivity to changing climate: Plio-Pleistocene erosion and sedimentation in SE ArizonaArjun Heimsath, Arizona State UniversityEAR-1124460ABSTRACTRemnants of sedimentary basin levels in southeastern Arizona are prominent and striking deposits, and as such they have attracted the attention of geologists from the early 20th century through the present. Despite extensive descriptive work capturing their visual conspicuousness, there is little consensus on the ages or geologic origins of these deposits. Although the sediments with which these landforms were built have obvious source areas that can be traced and mapped, the potential combinations of tectonic and climatic forces conspiring to leave such deposits abandoned are far from clear and have not been well examined. The ages inferred for loosely correlative basin high stands have ranged from ~20,000 years ago to 1.0-2.2 Ma and are based more on conjecture than quantitative geochronology. This project will establish an absolute timeline for the final stages of when these basin were filled with sediments, as well as when the basins were subsequently incised and dissected by regional erosional events. Establishing such a timeline requires application and development of cosmogenic nuclide methodology that will extend its temporal reach and test the innovative use of multiple stable and radio-nuclides. The sampling strategy will cover a broad range of sedimentary basin levels across southeast Arizona and will quantify both the ages of the deposits and the source area erosion rates. Because the undeformed basin high stand surfaces and underlying basin fill may date to the time that active tectonic forcing ceased in the region, the erosion of the surfaces is likely to have been driven by climatic forcing. Firmly establishing the chronology of these features, as well as the paleo-erosion rates of the source areas thus helps to build a bridge in understanding between how tectonic and climatic forces shape the Earth?s surface.The visually arresting nature of these surfaces across southeastern Arizona insures broad interest in their origins as well as how they may enable insight into tectonic and climatic forces. By establishing the geochronology of such widely studied and virtually undated landscapes we will expand the intellectual reach of this project well beyond the testing of hypotheses. Specifically, the Sky Island Alliance will help us coordinate how understanding the impacts of past climates on the landscape will help better predict future changes across the ecologically sensitive areas of this study. Each of the sedimentary deposits that we are studying originates in source area that is now home to endemic species and spatially isolated ecosystems. There is, therefore, interdisciplinary interest in quantitatively understanding how these landscapes change under different climate regimes. Additionally, the NSF-funded Jemez River Critical Zone Observatory (CZO), run by colleagues at the University of Arizona, has field sites near some of our field sites. We are coordinating field efforts and dating strategies with them, thus insuring synergy between projects with intellectual overlap, but very different project objectives. We will coordinate training and outreach of undergraduate and K-12 students with both collaborators, thus further widening the reach of the project. Collaborative research between this project and the Berkeley Geochronology Center will help develop facilities at Arizona State University as well as train graduate students. Finally, class trips to the field areas used for this project are helping to develop both the field component and the curriculum of undergraduate and graduate courses taught in our school.