The chemical structure of the Hawaiian mantle plume
The chemical structure of the Hawaiian mantle plume
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DOI：
10.1038/nature03907
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发表时间：
2004-10
期刊：
影响因子：
64.8
通讯作者：
Zhong‐Yuan Ren;S. Ingle;E. Takahashi;N. Hirano;T. Hirata
中科院分区：
文献类型：
--
作者：
Zhong‐Yuan Ren;S. Ingle;E. Takahashi;N. Hirano;T. Hirata
夏威夷-帝王火山岛和海山链通常被归因于位于太平洋岩石圈下方的热地幔热柱，它将来自地幔深处的物质输送到地表。夏威夷群岛的盾状火山呈两条曲线平行分布，其岩石具有普遍的地球化学差异、。这导致了这样一种命题，即夏威夷火山在成分上不同的、同心分区的下伏地幔热柱区域。熔融包裹体，或在结晶过程中冻结在橄榄石斑晶中的当地岩浆样本，可能记录地幔来源的复杂性，从而更好地洞察羽流的化学结构。在这里，我们报道了在个别的屏蔽期夏威夷火山中--甚至在单一岩石样品中--橄榄石寄主的熔体包裹体中发现了类似Kea和Loa的主要和微量元素成分。根据这些数据，我们推断，一种地幔源组分可能主宰了单一的熔岩流，但无论火山的具体地理位置如何，在所有熔岩中，两种地幔源组分在一定程度上是一致的。因此，我们认为夏威夷地幔热柱不太可能在成分上呈中心带状分布。相反，观测到的化学变化可能是由羽流的热结构控制的。
The Hawaiian–Emperor volcanic island and seamount chain is usually attributed to a hot mantle plume, located beneath the Pacific lithosphere, that delivers material sourced from deep in the mantle to the surface,,,,. The shield volcanoes of the Hawaiian islands are distributed in two curvilinear, parallel trends (termed ‘Kea’ and ‘Loa’), whose rocks are characterized by general geochemical differences,,,. This has led to the proposition that Hawaiian volcanoes sample compositionally distinct, concentrically zoned, regions of the underlying mantle plume,. Melt inclusions, or samples of local magma ‘frozen’ in olivine phenocrysts during crystallization, may record complexities of mantle sources, thereby providing better insight into the chemical structure of plumes. Here we report the discovery of both Kea- and Loa-like major and trace element compositions in olivine-hosted melt inclusions in individual, shield-stage Hawaiian volcanoes—even within single rock samples. We infer from these data that one mantle source component may dominate a single lava flow, but that the two mantle source components are consistently represented to some extent in all lavas, regardless of the specific geographic location of the volcano. We therefore suggest that the Hawaiian mantle plume is unlikely to be compositionally concentrically zoned. Instead, the observed chemical variation is probably controlled by the thermal structure of the plume.