Melt Transport from Mantle Plumes: Integrated Studies of Xenoliths and Associated Basalts from Oceanic Islands

9315698 Hauri这项新提议将对下列大洋岛屿上的碱性玄武岩所寄存的超镁铁质包体进行详细的结构、温度压力、离子探针和锶-钕-铅和锶同位素分析：萨瓦伊岛(西萨摩亚)、图布艾岛(南岛)、塔希提岛和塔哈阿岛(社会群岛)、希瓦岛、乌阿胡卡和努卡希瓦(马尔科萨斯群岛)、瓦胡岛(夏威夷群岛)和艾图塔基(库克群岛)。通过对图布艾岛、瓦胡岛(库劳火山和火奴鲁鲁火山)毛纳罗阿和塔哈岛的受地层控制的玄武岩剖面进行锶、钕、铅和Os同位素研究，将研究这些捕虏体与这些岛屿火山活动的关系。我们建议广泛使用Os同位素作为橄榄岩和地幔岩浆中相容元素的示踪剂，以区分熔体与岩石圈和地幔来源的相互作用。研究将侧重于以下具体问题：1)大洋圈闭包体的地幔热柱与岩石圈成因；2)大洋岩石圈来源对大洋岛屿玄武岩同位素变化的贡献；3)作为岩石圈年龄、厚度和温度的函数，个别岛屿之下岩浆-地幔的对比样式和产物；以及4)岩浆迁移的物理和化学特征在多大程度上受地幔结构和粒度变化的控制。

9315698 Hauri This new proposal will apply detailed textural, thermobarometry, ion microprobe, and Sr-Nd-Pb and Os isotopic analyses to suites of ultramafic xenoliths hosted by alkali basalts on the oceanic islands of Savai'i (Western Samoa), Tubuai (Austral Islands), Tahiti and Tahaa (Society Islands), Hiva Oa, Ua Huka and Nuka Hiva (Marquesas Islands), Oahu (Hawaiian Islands) and Aitutaki (Cook Islands). The relationship of these xenolith suites to volcanism at these islands will be examined by undertaking Sr, Nd, Pb and Os isotopic studies of stratigraphically controlled basalt sections from Tubuai, Oahu (Koolau and Honolulu Volcanics) Mauna Loa, and Tahaa. We propose extensive use of Os isotopes as tracers of compatible elements in peridotites and mantle-derived magmas in order to distinguish melt interaction with lithospheric versus plume derived mantle sources. Research will focus on specific issues such as: 1) mantle plume versus lithospheric origin for OIB-hosted xenoliths, 2) contribution of the oceanic lithosphere sources to isotopic variations in oceanic island basalts, 3) contrasting styles and products of magma-mantle beneath individual islands, as a function of lithospheric age, thickness, and temperature, and 4) the extent to which the physical and chemical characteristics of magma migration are controlled by variations in texture and grain size of the mantle.