Lava-Dam Outburst Floods and Related Volcanic Features in Western Grand Canyon

西大峡谷熔岩坝溃决洪水及相关火山特征pis建议使用宇宙成因3He定年结合水文、岩石学和地球化学技术来解决科罗拉多河第四纪溃决洪水的历史。这项工作将补充一些熔岩流的40Ar/39Ar工作，以及熔岩的地球化学表征。初步的3He年代测定提供了熔岩流和爆发洪水的证据，比以前的K/Ar年代测定要年轻得多，这大大改变了对大峡谷西部地貌演化的解释。他们将对玄武岩表面进行测年，这些玄武岩表面被主要洪水事件冲刷过，爆发洪水沉积物，熔岩流，废弃的冲刷通道，以及栖息的巨石坝，以限制大峡谷西部晚第四纪的事件。这项工作将使他们能够将熔岩流与熔岩坝和溃决洪水沉积物联系起来，并根据古洪水证据估计洪水的震级。这项工作将极大地改变对大峡谷西部地貌演化的解释，因为它能够准确地确定过去50万年的时间。

Lava-Dam Outburst Floods and Related Volcanic Features in Western Grand CanyonPIs propose to use cosmogenic 3He dating combined with hydrologic, petrographic, and geochemical techniques to resolve the history of Quaternary outburst floods in the Colorado River. This work will be supplemented by 40Ar/39Ar work on some lava flows, and by geochemical characterization of lavas. Preliminary 3He dating provides evidence for lava flows and outburst floods much younger than have been previously dated by K/Ar, significantly changing interpretations of the geomorphic evolution of western Grand Canyon. They will date basalt surfaces scoured by major flood events, outburst flood deposits, lava flows, abandoned scour channels, and perched boulder bars to constrain late Quaternary events in the western Grand Canyon. This work will allow them to correlate lava flows with lava dams and outburst flood deposits and to estimate flood magnitudes based on paleoflood evidence. This work will significantly change interpretations of the geomorphic evolution of western Grand Canyon because of the ability to accurately date events of the last 0.5 million years.