Detrital Zircon Geochronology of Colorado Plateau Mesozoic Strata: Implications for Continental Paleogeography and Paleotectonics

科罗拉多高原中生代地层的碎屑锆石年代学：大陆古地理和古构造学的意义W.R.Dickinson，G.E.Gehrels，P.G.DeCelle(亚利桑那大学)EAR-0341987 EAR-0341987通过测定锆石中所含铀和铅的同位素比率获得矿物锆石单个砂粒的放射性年龄的能力现在使确定为沉积地层贡献沙粒的侵蚀基岩来源的年龄成为可能。通过首次系统地将这项技术应用于科罗拉多高原的地层，我们希望将对该大陆中生代古地理的理解提高到以前无法达到的水平。科罗拉多高原揭示了北美最完整的中生代地层序列。通过将北美不同地区潜在基岩物源的年龄知识与科罗拉多高原地层中锆石颗粒年龄的新信息结合起来，我们可以推断出中生代古河流的模式，以及负责沉积全球地质记录中最大的大片古丘田的古风系统。了解中生代以来横贯大陆的沉积物运移方向将反过来揭示大陆边缘的阿巴拉契亚山脉(东部)和科迪勒山脉(西部)的演化，因为古流域起源于高地，并随着高地被构造活动抬升或被侵蚀而改变形态。该项目的设计涉及本科生作为教职调查人员的初级同事参与研究的所有阶段。

Detrital Zircon Geochronology of Colorado Plateau Mesozoic Strata: Implications for Continental Paleogeography and PaleotectonicsW.R. Dickinson, G.E. Gehrels, P.G. Decelles (University of Arizona)EAR-0341987ABSTRACTThe ability to obtain radiometric ages for individual sand grains of the mineral zircon by determining isotopic ratios of uranium and lead contained within the zircon now makes it possible to establish the ages of the eroded bedrock sources that contributed sand grains to sedimentary strata. By applying this technique systematically for the first time to strata of the Colorado Plateau, which exposes the most complete Mesozoic succession in North America, we expect to advance our understanding of the Mesozoic paleogeography of the continent to a level not previously attainable. By coupling knowledge of the ages of potential bedrock sources in different parts of North America with the new information on the ages of zircon grains in strata of the Colorado Plateau, we can infer the patterns of Mesozoic paleorivers that transported sand across the ancient continental surface, and of paleowind systems responsible for deposition of vast paleodune fields that are among the largest in the global geologic record. Knowing the directions of transcontinental sediment transport through Mesozoic time will shed light in turn on evolution of the Appalachian (eastern) and Cordilleran (western) mountain chains of the continental margins because paleodrainages head in highlands, and change configuration as highlands are uplifted by tectonic activity or subdued by erosion. The design of the project involves participation by undergraduate students in all phases of the research as junior colleagues of the faculty investigators.