New incision rates along the Colorado River system based on cosmogenic burial dating of terraces: Implications for regional controls on Quaternary incision
New incision rates along the Colorado River system based on cosmogenic burial dating of terraces: Implications for regional controls on Quaternary incision
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DOI：
10.1130/ges00724.1
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发表时间：
2012-10
期刊：
影响因子：
2.5
通讯作者：
A. Darling;K. Karlstrom;D. Granger;A. Aslan;E. Kirby;W. Ouimet;G. Lazear;D. Coblentz;R. Cole-R.
中科院分区：
文献类型：
--
作者：
A. Darling;K. Karlstrom;D. Granger;A. Aslan;E. Kirby;W. Ouimet;G. Lazear;D. Coblentz;R. Cole-R.
新的宇宙成因埋藏和公布日期的科罗拉多和绿色河流阶地被用来推断变量的切割率沿着河流在过去的10马。利斯渡口的一个缺口将科罗拉多河流域的上游和下游分开。在犹他州牛蛙盆地（Bullfrog Basin，Lees Ferry上游）一个190 m高的斯特拉特阶地上获得了1.5 ± 0.13 Ma的等时宇宙成因埋藏年龄。这个年龄产生的平均切割率为126 + 12/-10 m/Ma以上的断点，是三倍以上的宇宙成因的表面年龄在同一阶地，这表明表面日期推断暴露年龄可能是最低年龄。Lees Ferry以下的切割速率更快，约为170 m/Ma-230 m/Ma，表明在过去的几百万年里，上游的断点迁移。Hite（Lees Ferry上方）的阶地产生的等时线埋藏年龄为0.29 ± 0.17 Ma，速率为300-900 m/Ma，证实了Glen峡谷的切割加速。在上游盆地内，犹他州Desolation峡谷绿色河附近60 m阶地上的等时宇宙成因埋藏年龄为1.48 ± 0.12 Ma，怀俄明州Flaming Gorge上游120 m阶地上的等时宇宙成因埋藏年龄为1.2 ± 0.3 Ma，分别给出41± 3 m/Ma和100 + 33/-20 m/Ma的切割速率。相比之下，切口率沿着上游科罗拉多河是150米/马超过0.64和10 Ma的时间框架。较高的切口率，梯度，并沿着上科罗拉多河相对于绿色河的流量是一致的差异岩石隆起的科罗拉多落基山脉相对于科罗拉多高原。
New cosmogenic burial and published dates of Colorado and Green river terraces are used to infer variable incision rates along the rivers in the past 10 Ma. A knickpoint at Lees Ferry separates the lower and upper Colorado River basins. We obtained an isochron cosmogenic burial date of 1.5 ± 0.13 Ma on a 190-m-high strath terrace near Bullfrog Basin, Utah (upstream of Lees Ferry). This age yields an average incision rate of 126 +12/–10 m/Ma above the knickpoint and is three times older than a cosmogenic surface age on the same terrace, suggesting that surface dates inferred by exposure dating may be minimum ages. Incision rates below Lees Ferry are faster, ∼170 m/Ma–230 m/Ma, suggesting upstream knickpoint migration over the past several million years. A terrace at Hite (above Lees Ferry) yields an isochron burial age of 0.29 ± 0.17 Ma, and a rate of ∼300–900 m/Ma, corroborating incision acceleration in Glen Canyon. Within the upper basin, isochron cosmogenic burial dates of 1.48 ± 0.12 Ma on a 60 m terrace near the Green River in Desolation Canyon, Utah, and 1.2 ± 0.3 Ma on a 120 m terrace upstream of Flaming Gorge, Wyoming, give incision rates of 41± 3 m/Ma and 100 +33/–20 m/Ma, respectively. In contrast, incision rates along the upper Colorado River are 150 m/Ma over 0.64 and 10 Ma time frames. Higher incision rates, gradient, and discharge along the upper Colorado River relative to the Green River are consistent with differential rock uplift of the Colorado Rockies relative to the Colorado Plateau.