Silicic volcanism at an off-axis geothermal field in the Mariana Trough back-arc basin
Silicic volcanism at an off-axis geothermal field in the Mariana Trough back-arc basin
复制标题
DOI：
10.1130/0016-7606(1985)96
复制
发表时间：
1985-07
影响因子：
4.9
通讯作者：
P. Lonsdale;J. Hawkins
中科院分区：
文献类型：
--
作者：
P. Lonsdale;J. Hawkins
在马里亚纳海槽活动海脊西侧3英里处有一个局部高热流的深海丘陵遗址，有几组倾斜的断层陡峭，由多束凌日绘制，以及用Deep Tow测量检查的直径为50至1000米的圆顶群。一些圆顶，包括20到30米高的覆盖着锰氧化物的小岩石旋钮，从沉积物覆盖层中露出，但是，尽管有热流证据表明它们是热液排放的地点，但这些基岩特征与一些大洋中脊上发现的热液丘陵有着根本的不同。挖掘一个圆顶发现了一块流纹岩浮石，我们认为它在盆地内2,600-3,600米深喷发。硅质岩可能是拉斑玄武岩岩浆的极端差异，但更有可能的来源是盆地沉积充填物的部分熔融。
An abyssal-hill site with localized high heat flow on the 3-m.y.-old west flank of the active ridge in the Mariana Trough has sets of oblique fault scarps, mapped by multi-beam transits, and clusters of 50- to 1,000-m-diameter domes examined with a Deep Tow survey. Some of the domes, including small, 20- to 30-m-high rocky knobs encrusted with manganese oxide, crop out through the sediment cover, but, despite heat-flow evidence that they are sites of hydrothermal discharge, these bedrock features are fundamentally different from the hydrothermal mounds found on some mid-ocean ridges. Dredging one dome recovered a rhyodacite pumice that we believe erupted at a depth of 2,600–3,600 m within the basin. The siliceous rock may be an extreme differentiate of a tholeiitic magma, but a more likely origin is partial melting of the basin's sedimentary fill.