CAREER: Paleotopography using Clumped Isotopes in the Basin and Range: Refining the Three Dimensional Evolution of a Continental Extensional Province

职业：在盆地和山脉中使用丛集同位素进行古地形学：完善大陆伸展省的三维演化

• 批准号: 1151247
• 负责人: Nathan Niemi
• 金额: $ 51万
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-06-01 至 2018-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1151247&HistoricalAwards=false
• 关键词: CAREER; Paleotopography; using; Clumped; Isotopes

The Basin and Range province of the western United States is perhaps the best exposed and most accessible example of an intracontinental extensional province on Earth today. Although a variety of lines of geological and geophysical evidence indicate that this region has experienced approximately 200% east-west extension since middle Miocene time, the Basin and Range is underlain today by continental crust of typical (30 km) thickness, but that lies at an average elevation (1-1.5 km) substantially higher than one would expect based on simple geophysical calculations. How the continental crust of the Basin and Range has evolved throughout Cenozoic time to have the characteristics that it has today is an outstanding question that bears directly on the nature of diffuse continental deformation, far away from plate boundaries, and the processes that lead the crust to stretch and thin without rupturing to create new oceanic basins. A variety of tectonic models have been invoked to explain the evolution of the Basin and Range, but the geologic observations that would allow one to discriminate between these models are unresolved. One potential discriminant between these models is the predictions each makes for the paleoelevation history of the western United States. Recent advances in the development of paleo-thermometers, using clumped isotopes in lacustrine carbonates, offers a new approach to determining paleotemperatures from the geologic record, and thus, indirectly the paleoelevations at which the carbonates formed. By applying these new methods to measure the temperature differences between a suite of low-elevation, near sea-level lacustrine carbonates, and coeval lacustrine carbonates in the Basin and Range, this project will develop new constraints on the temporal and spatial evolution of topography across the Basin and Range throughout its Cenozoic evolution, and thus address several key questions about the tectonic evolution of the Basin and Range, including: (1) Was the Basin and Range a high-standing plateau prior to extension?; (2) What was the spatial extent of such a plateau, if it existed?; (3) How did the elevation of the Basin and Range change during late Cenozoic extension?; and (4) What processes accommodated large-magnitude extension in late Cenozoic time?This research will be incorporated into an education and outreach program directed at early middle-school-aged students in the Greater Detroit area through the development and production of a full-dome planetarium movie on plate tectonics, in collaboration with the Exhibit Museum of Natural History and the 3DLabs at the University of Michigan. Early in middle school is the time when many students begin to lose interest in science. This educational project will incorporate the research data gathered from this project, along with the wealth of geological and geophysical data being collected from other ongoing NSF projects, such as Earthscope, into a fully immersive film on the history of the Earth, the processes that drive plate tectonics, the hazards associated with plate boundaries, and the technology we can apply to study modern plate motions. This movie will be incorporated into outreach days on earth sciences at the Exhibit Museum, which reach 3,000-6,000 students annually, and which are designed to get students to think of science as an active and evolving field of study. By developing new and engaging ways of presenting earth science that demonstrate the elements of excitement of discovery and societal relevance that draw in so many who study the earth, the project aims to increase the participation of students in STEM subjects through middle school and beyond.

美国西部的盆地和山脉省可能是当今地球上最容易接触到的陆内伸展省的例子。尽管各种地质和地球物理证据表明，该地区自中新世以来经历了约200%的东西向伸展，但该盆地和山脉今天被典型的(30公里)厚度的陆壳覆盖，但其平均海拔(1-1.5公里)大大高于根据简单地球物理计算得出的预期。盆地和山脉的陆壳是如何在整个新生代时期演化成今天所具有的特征的，这是一个突出的问题，它直接关系到远离板块边界的扩散大陆变形的性质，以及导致地壳拉伸和变薄而不破裂以形成新的洋盆的过程。人们引用了各种构造模型来解释盆地和山脉的演化，但能够区分这些模型的地质观察尚未得到解决。这些模型之间的一个潜在区别是，每个模型都对美国西部的古海拔历史做出了预测。利用湖相碳酸盐中的块状同位素发展古温度计的最新进展，提供了一种根据地质记录确定古温度的新方法，从而间接地确定了形成碳酸盐的古海拔。通过应用这些新方法来测量盆地和山脉中一套低海拔、接近海平面的湖泊碳酸盐和同时代湖泊碳酸盐之间的温差，这个项目将在整个新生代演化过程中对盆地和山脉的地形的时空演变产生新的限制，从而解决关于盆地和山脉构造演化的几个关键问题，包括：(1)盆地和山脉在伸展之前是高海拔高原吗？(2)这样的高原的空间范围是什么，如果它存在的话？(3)盆地和山脉的高程在晚新生代伸展期间是如何变化的？(4)晚新生代是什么过程适应了大规模的伸展？这项研究将被纳入一个针对大底特律地区早期中学生的教育和推广计划，与密歇根大学自然历史陈列馆和3DLabs合作，开发和制作一部关于板块构造的全穹顶天文电影。中学早期是许多学生开始对科学失去兴趣的时期。这个教育项目将把从这个项目中收集的研究数据，以及从其他正在进行的NSF项目(如Earthcope)收集的丰富的地质和地球物理数据，整合到一个关于地球历史、驱动板块构造的过程、与板块边界相关的灾害以及我们可以应用于研究现代板块运动的技术的完全身临其境的电影中。这部电影将被纳入展览馆的地球科学外展日，每年有3,000-6,000名学生参加，旨在让学生将科学视为一个活跃和不断发展的研究领域。通过开发展示地球科学的新的、引人入胜的方式，展示发现的兴奋和社会相关性的元素，吸引了如此多研究地球的人，该项目旨在增加学生在中学及以后的STEM科目的参与度。