Explosive basaltic and rhyolitic volcanism of the eastern Snake River Plain
Explosive basaltic and rhyolitic volcanism of the eastern Snake River Plain
复制标题
蛇河平原东部爆发性玄武质和流纹质火山活动
DOI：
10.1029/ft305p0038
复制
发表时间：
2013
期刊：
影响因子：
--
通讯作者：
W. Hackett
中科院分区：
文献类型：
--
作者：
L. Morgan;W. Hackett
在本指南中，我们讨论了蛇河平原东部及其沿着边缘的新近纪流纹岩和玄武岩。强调了爆发性火山作用的物理过程和沉积物，包括流纹岩熔结凝灰岩（灰流凝灰岩）和基性岩浆与外部水相互作用过程中形成的玄武质水火山特征。图1是实地考察的索引图，实地考察有九个站点，预计需要两天时间。第一天涵盖了沿着从爱达荷州福尔斯到海瑟的斯内克河平原东部南缘以及沿着斯内克河南支流（1 -5号站点）的流纹岩和玄武质沉积物。第二天包括雷克斯堡附近梅南火山杂岩的玄武岩凝灰岩和沿着从杜波依斯到豪角的斯内克河平原东部北方边缘的流纹凝灰岩（第6-9站）。蛇河平原是爱达荷州南部的主要地貌特征，覆盖了该州近四分之一的土地。火山岩和沉积岩形成了一个40到60英里宽的弧形带，从莎士比亚和俄勒冈州的边界延伸到黄石国家公园大约400英里。斯内克河平原的一个显著特征是流纹质火山作用一般从西南向东北逐渐变年轻（Armstrong等，1975）（图2）。这导致人们猜测，东部蛇河平原是北美西部地幔柱的痕迹，或者是一个向东的-
In this guide, we discuss Neogene rhyolite and Quatemary basalt on the eastern Snake River Plain and along its margins. The physical processes and deposits of explosive volcanism are emphasized, including rhyolite ignimbrites (ash-flow tuffs) and basaltic hydrovolcanic features that formed during interaction between basic magma and external water. Figure 1 is an index map for the field trip, which has nine stops and is intended to take two days. The first day covers rhyolitic and basaltic deposits along the southern margin of the eastern Snake River Plain from Idaho Falls to Heise and along the South Fork of the Snake River (Stops l-5). The second day includes basaltic tuffs of the Menan volcanic complex near Rexburg and rhyolitic tuffs along the northern margin of the eastern Snake River Plain from Dubois to Howe Point (Stops 6-9). The Snake River Plain is the dominant geomorphic feature of southern Idaho and covers nearly a quarter of the state. Volcanic and sedimentary rocks form a 40to 60-mile-wide, arcuate belt that extends about 400 miles from the Idaho-Oregon border to Yellowstone National Park. A remarkable feature of the Snake River Plain is that the rhyolitic volcanism generally becomes younger from southwest to northeast (Armstrong and others, 1975) (Fig. 2). This has led to speculation that the eastern Snake River Plain is the trace of a mantle plume beneath western North America or the tip of an eastward-