Dalrymple G B, Hamblin W K
College of Oceanic and Atmospheric Sciences, 104 Ocean Administration Building, Oregon State University, Corvallis, OR 97331, USA.
Proc Natl Acad Sci U S A. 1998 Aug 18;95(17):9744-9. doi: 10.1073/pnas.95.17.9744.
At least 13 times during the Pleistocene Epoch lava flowed into the inner gorge of the Grand Canyon and formed lava dams, as high as 600 m, that temporarily blocked the flow of the Colorado River. K-Ar ages on these lava dams indicate that the seven youngest formed within a short period of time between about 0.6 and 0.4 mega-annum (Ma). The physiography of the lava dam remnants within the canyon shows that each dam was destroyed by erosion, the Colorado River rapidly reaching its pre-existing grade level, before the next dam was emplaced by new eruptions. The total time for emplacement and destruction for an individual lava dam was probably as little as 0. 01-0.02 million years. The K-Ar ages of the two oldest dams, the Lava Butte dam (0.577 +/- 0.054 Ma) and the Prospect dam (0.684 +/- 0.051 Ma) are somewhat younger than the physiography of their remnants suggest.
在更新世时期，熔岩至少有13次流入大峡谷的内峡谷并形成了高达600米的熔岩坝，这些熔岩坝暂时阻挡了科罗拉多河的水流。对这些熔岩坝的钾-氩年代测定表明，最年轻的七个熔岩坝是在大约0.6至0.4百万年（Ma）的短时间内形成的。峡谷内熔岩坝残余物的地貌显示，每个熔岩坝都被侵蚀破坏，在新的火山喷发形成下一个熔岩坝之前，科罗拉多河迅速恢复到先前的河床高度。单个熔岩坝的形成和破坏总时间可能短至0.01 - 0.02百万年。两个最古老的熔岩坝，即熔岩丘坝（0.577 +/- 0.054 Ma）和远景坝（0.684 +/- 0.051 Ma）的钾-氩年代比其残余物的地貌所显示的年代要稍年轻一些。
