MANTLE PLUMES FROM ANCIENT OCEANIC-CRUST
MANTLE PLUMES FROM ANCIENT OCEANIC-CRUST
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DOI：
10.1016/0012-821x(82)90161-3
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发表时间：
1982-01-01
影响因子：
5.3
通讯作者：
WHITE, WM
中科院分区：
文献类型：
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作者：
HOFMANN, AW;WHITE, WM
对于“热点”火山活动的起源，我们提出以下模型：洋壳在俯冲过程中返回到地幔。它与周围的橄榄岩分离，沉入更深的地幔中，并以一定程度的密度补偿积累，可能是核幔边界。局部累积层厚度超过100公里。最终，它由于内部加热而变得不稳定，由此产生的底辟成为洋岛玄武岩（OIB）和其他热点火山活动的源羽流。正如摩根所建议的，这种机制可能会引发上地幔对流[1]。我们的模型为以下问题提供了可能的解释：(1) OIB 的高微量元素浓度，(2) OIB 源中亲岩浆元素富集和损耗的看似矛盾的同位素证据，(3) 大洋玄武岩中明显的地幔等时线现象，以及 (4) 大陆火成岩活动明显的幕式性质。随着有关洋壳实际整体成分（包括其蚀变产物和沉积物覆盖）的知识不断积累，该模型可以得到进一步测试。
We propose the following model for the origin of “hot-spot” volcanism: Oceanic crust is returned to the mantle during subduction. It is separated from the surrounding peridotite, it sinks into the deeper mantle and accumulates at some level of density compensation, possibly the core-mantle boundary. The accumulated layerlocally reaches thicknesses exceeding 100 km. Eventually, it becomes unstable as a consequence of internal heating, and the resulting diapirs become the source plumes of ocean island basalts (OIB) and other hot-spot volcanism. This mechanism may trigger upper mantle convection as suggested by Morgan [1]. Our model provides possible explanations for (1) the high traceelement concentrations of OIB, (2) the seemingly contradictory isotopic evidence for both enrichment and depletion of magmaphile elements in OIB sources, (3) the phenomenon of apparent mantle isochrons in oceanic basalts, and (4) the apparently episodic nature of continental igneous activity. The model can be tested further, as more knowledge accumulates about the actual bulk composition of the oceanic crust, including its alteration products and sediment cover.