Neogene Fallout Tuffs from the Yellowstone Hotspot in the Columbia Plateau Region, Oregon, Washington and Idaho, USA
Neogene Fallout Tuffs from the Yellowstone Hotspot in the Columbia Plateau Region, Oregon, Washington and Idaho, USA
复制标题
美国俄勒冈州、华盛顿州和爱达荷州哥伦比亚高原地区黄石热点地区的新近纪沉降凝灰岩
作者：
B. Nash;M. E. Perkins
太平洋西北部哥伦比亚高原地区的沉积序列年龄范围为16-4 Ma，其中含有沉降凝灰岩，其起源位于内华达州西北部、俄勒冈州东部和爱达荷州蛇河平原的黄石热点的火山中心。硅质火山活动开始在该地区的早期喷发的哥伦比亚河玄武岩群（CRBG），和广泛的沉降凝灰岩的丰富提供了机会，建立一个火山灰地层框架的区域。具有火山岩沉积物的沉积盆地还包含在中新世中期气候适宜期保存下来的各种动物群和植物群，包括沙克尔溪、马斯科、拉塔、维尔京谷和特劳特克里克。灰降单元的对比表明，俄勒冈州东部的布利溪地层下部与俄勒冈州和爱达荷州的维珍谷地层、吸盘溪地层、俄勒冈州的特劳特克里克地层以及华盛顿州和爱达荷州清水湾的拉塔地层是同时代的。此外，可以确定的是，特劳特克里克的植物群比马斯科和拉塔植物群年轻。从克拉克化石层，爱达荷州，浮岩床在布利河形成的地方非常保存完好的克拉克植物群组合之间的马斯科和特劳特克里克植物群的沉降凝灰岩的初步相关性。11.8和10.1马之间的Bruneau-Jarbidge和双福尔斯火山中心的黄石热点在蛇河平原中部的大体积超喷发沉积大量的沉降凝灰岩在Ellensberg形成CRBG沉积夹层。这些事件将这些沉降凝灰岩的已知分布延伸到蛇河平原源头西北500公里处。迄今为止，这些大喷发的远距离产物只在内布拉斯加州和堪萨斯高平原的源头以东被发现。
Sedimentary sequences in the Columbia Plateau region of the Pacific Northwest ranging in age from 16–4 Ma contain fallout tuffs whose origins lie in volcanic centers of the Yellowstone hotspot in northwestern Nevada, eastern Oregon and the Snake River Plain in Idaho. Silicic volcanism began in the region contemporaneously with early eruptions of the Columbia River Basalt Group (CRBG), and the abundance of widespread fallout tuffs provides the opportunity to establish a tephrostratigrahic framework for the region. Sedimentary basins with volcaniclastic deposits also contain diverse assemblages of fauna and flora that were preserved during the Mid-Miocene Climatic Optimum, including Sucker Creek, Mascall, Latah, Virgin Valley and Trout Creek. Correlation of ashfall units establish that the lower Bully Creek Formation in eastern Oregon is contemporaneous with the Virgin Valley Formation, the Sucker Creek Formation, Oregon and Idaho, Trout Creek Formation, Oregon, and the Latah Formation in the Clearwater Embayment in Washington and Idaho. In addition, it can be established that the Trout Creek flora are younger than the Mascall and Latah flora. A tentative correlation of a fallout tuff from the Clarkia fossil beds, Idaho, with a pumice bed in the Bully Creek Formation places the remarkably well preserved Clarkia flora assemblage between the Mascall and Trout Creek flora. Large-volume supereruptions that originated between 11.8 and 10.1 Ma from the Bruneau-Jarbidge and Twin Falls volcanic centers of the Yellowstone hotspot in the central Snake River Plain deposited voluminous fallout tuffs in the Ellensberg Formation which forms sedimentary interbeds in the CRBG. These occurrences extend the known distribution of these fallout tuffs 500 km to the northwest of their source in the Snake River Plain. Heretofore, the distal products of these large eruptions had only been recognized to the east of their sources in the High Plains of Nebraska and Kansas.
影响因子：
3.5
作者：
B. Ellis;T. Barry;M. Branney;John A. Wolff;I. Bindeman;Rob Wilson;B. Bonnichsen
通讯作者：
B. Ellis;T. Barry;M. Branney;John A. Wolff;I. Bindeman;Rob Wilson;B. Bonnichsen