Cosmogenic 3He exposure ages of Pleistocene debris flows and desert pavements in Capitol Reef National Park, Utah
Cosmogenic 3He exposure ages of Pleistocene debris flows and desert pavements in Capitol Reef National Park, Utah
复制标题
犹他州圆顶礁国家公园更新世泥石流和沙漠路面的宇宙成因 3He 暴露年龄
DOI：
10.1016/j.geomorph.2004.11.004
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发表时间：
2005
期刊：
影响因子：
3.9
通讯作者：
T. Cerling
中科院分区：
文献类型：
--
作者：
David W. Marchetti;T. Cerling
犹他州圆顶礁地区的第四纪历史与覆盖大部分景观的玄武岩-安山岩巨石沉积物密切相关。了解这些沉积物的年龄和沉积模式对于破译科罗拉多高原这一部分的第四纪演化至关重要。通过宇宙成因 3He 暴露年龄测定，我们获得了圆顶礁地区几个关键矿床的表观暴露年龄。覆盖约翰逊台地和卡卡斯溪台地的粗砾岩并不像之前认为的那样与布尔湖冰川作用有关，而是沉积于 180±15 至 205±17 ka（最小年龄），是泥石流沉积的结果。约翰逊梅萨表面的沙漠路面的暴露年龄范围为 97±8 至 159±14 ka，比巨石暴露年龄年轻 34-96 年。巨石和路面暴露年龄之间的偏移似乎与路面形成的延迟有关，直到倒数第二次冰期/间冰期过渡或自泥石流沉积以来路面碎屑的周期性掩埋和暴露。根据巨石暴露年龄计算得出，弗里蒙特河圆顶礁河段的切割率范围为 0.40 至 0.43 m kyear−1（最大率），并且是科罗拉多高原上最高的切割率之一。
The Quaternary history of the Capitol Reef area, Utah, is closely linked to the basaltic-andesite boulder deposits that cover much of the landscape. Understanding the age and mode of emplacement of these deposits is crucial to deciphering the Quaternary evolution of this part of the Colorado Plateau. Using cosmogenic3He exposure age dating, we obtained apparent exposure ages for several key deposits in the Capitol Reef area. Coarse boulder diamicts capping the Johnson Mesa and Carcass Creek Terraces are not associated with the Bull Lake glaciation as previously thought, but were deposited 180±15 to 205±17 ka (minimum age) and are the result of debris flow deposition. Desert pavements on the Johnson Mesa surface give exposure ranging from 97±8 to 159±14 ka and are 34–96 kyears younger than the boulder exposure ages. The offset between the boulder and pavement exposure ages appears to be related to a delay in pavement formation until the penultimate glacial/interglacial transition or periodic burial and exposure of pavement clasts since debris flow deposition. Incision rates for the Capitol Reef reach of the Fremont River calculated from the boulder exposure ages range from 0.40 to 0.43 m kyear−1(maximum rates) and are some of the highest on the Colorado Plateau.