Seismic evidence for active magmatic underplating beneath the Basin and Range Province, western United States
Seismic evidence for active magmatic underplating beneath the Basin and Range Province, western United States
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DOI：
10.1029/93jb02021
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发表时间：
1993-12
影响因子：
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通讯作者：
C. Jarchow;G. A. Thompson;R. Catchings;W. Mooney
中科院分区：
文献类型：
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作者：
C. Jarchow;G. A. Thompson;R. Catchings;W. Mooney
近垂直和广角地震反射数据提供了证据，证明在内华达州西北部的布埃纳维斯塔山谷下的地壳底部存在岩浆体。该岩浆体的地震响应特征为高振幅、近垂直的P波反射和强烈的P-S转换相。这里称之为布埃纳维斯塔岩浆体的岩浆体可能是一个厚度不超过200 m、长度不超过1.8 km的单一岩床。岩床中的熔体分数无疑大于20- 30%，并且可能超过50%。熔体组成不受约束。虽然布埃纳维斯塔岩浆体的年龄很难精确确定，但它可能不超过50万年。这表明，在盆地和山脉省的岩浆活动是一个持续的过程，尽管相对缺乏火山岩喷发在地表在过去的6百万年。
Near-vertical and wide-angle seismic reflection data provide evidence for the presence of a magma body at the base of the crust beneath Buena Vista Valley in northwestern Nevada. The seismic response of this hypothesized magma body is characterized by high-amplitude, near-vertical P wave reflections and a comparably strong P-to-S converted phase. The magma body, referred to here as the Buena Vista Magma Body, is probably a single sill with thickness no greater than 200 m and length no greater than 1.8 km. The melt fraction in the sill is undoubtedly greater than 20–30%, and probably exceeds 50%. Melt composition is unconstrained. Although the age of the Buena Vista Magma Body is difficult to determine precisely, it is probably no older than 500,000 years. This suggests that magmatism in the Basin and Range Province is an ongoing process, despite the relative paucity of volcanic rocks erupted at the surface during the last 6 m.y.