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更新世侵蚀和沉积亚利桑那州州立大学阿尔琼·海姆萨斯EAR-1124460ABSTRACTRACT亚利桑那州东南部沉积盆地的遗迹是突出而引人注目的沉积物，因此，从20世纪初到现在，它们一直受到地质学家的关注。尽管大量的描述性工作捕捉到了它们的视觉上的显眼之处，但对于这些矿床的时代或地质来源几乎没有达成一致意见。尽管建造这些地貌的沉积物有明显的来源区域，可以追踪和绘制地图，但导致这些沉积物被遗弃的构造和气候力量的潜在组合远不清楚，也没有得到很好的研究。松散相关的盆地高水位的年龄范围从大约2万年到1.0-2.2 Ma，更多的是基于猜测，而不是定量地质年代学。该项目将为这些盆地被沉积物充填的最后阶段以及随后这些盆地被区域侵蚀事件切割和解剖的最后阶段建立一个绝对时间表。建立这样一个时间表需要应用和发展宇宙核素方法，这种方法将扩大其时间范围，并测试多种稳定和放射性核素的创新使用。采样战略将涵盖亚利桑那州东南部广泛的沉积盆地水平，并将量化矿床的年龄和物源区的侵蚀速率。由于未变形的盆地高水位面和下伏盆地充填可能是该地区活动构造强迫停止的时间，因此地表的侵蚀很可能是由气候强迫驱动的。因此，确定这些特征的年表以及源区的古侵蚀速率有助于在了解构造和气候力量如何塑造地球-S表面之间建立一座桥梁。这些横跨亚利桑那州东南部的表面视觉上的扣人心弦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。通过建立这种广泛研究和几乎没有年代的景观的地质年代学，我们将扩大这个项目的智力范围，远远超出对假说的测试。具体地说，天空岛联盟将帮助我们协调了解过去气候对景观的影响如何有助于更好地预测这项研究的生态敏感地区的未来变化。我们正在研究的每一个沉积矿床都起源于现在是特有物种和空间隔离生态系统的源区。因此，在定量了解这些景观在不同气候制度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运营，在我们的一些野外站点附近设有野外站点。我们正在协调实地工作并与他们制定约会战略，从而确保智力重叠但项目目标截然不同的项目之间的协同效应。我们将与这两个合作者协调本科生和K-12学生的培训和外展，从而进一步扩大项目的覆盖范围。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发展亚利桑那州立大学的设施以及培养研究生。最后，到本项目所用领域的课堂旅行有助于开发我们学校教授的本科生和研究生课程的领域部分和课程。

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.