The Geochemical Characteristics of the Hawaiian Plume: Constraints From Studies of Lavas Forming the Koolau and Kahoolawe Shields

夏威夷羽流的地球化学特征：来自形成 Koolau 和 Kahoolawe 地盾的熔岩研究的限制

• 批准号: 0105557
• 负责人: Frederick Frey
• 金额: $ 26.33万
• 依托单位: Massachusetts Institute of Technology
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-08-01 至 2006-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0105557&HistoricalAwards=false
• 关键词: Geochemical; Characteristics; Hawaiian; Plume; Constraints

FreyEAR-0105557Terrestrial volcanoes are associated with three different tectonicsettings. Two are associated with plate boundaries, that is, regions ofplate divergence and convergence, and the third is intraplate volcanism.Magmas erupted in these different environments differ significantly ingeochemical characteristics. In this proposed research the goal is tounderstand the source and processes which determine the geochemicalcharacteristics of Hawaiian lavas. This endmember is of great interestbecause it may in part represent the consequences of subducting oceaniccrust deep into the mantle at subduction zones.The approach will be to determine abundances of major and trace elementsand isotopic ratios of O, Sr, Nd, Pb, Hf and Os in lavas of varyingrelative age from these two shields. For Koolau the samples to be studiedare from a recently drilled core, that penetrates the shield to a greaterdepth and older age than previously studied surficially exposed samples.For Kahoolawe, which has not been intensively studied, the samples will befrom several stratigraphic sections across the shield. The principalobjective is to understand the source components contributing to thesemagmas; hence emphasis will be on evaluating correlations between abundanceratios of highly incompatible elements, e.g., Ba/Th, Ce/Pb and La/Nb, andisotopic ratios. These geochemical characteristics will be determinedusing analytical facilities such as inductively couples plasma massspectrometry and thermal ionization mass spectrometry.Because of their oceanic plate setting, relatively simple mineralogy and awealth complementary studies, Hawaiian volcanoes present the bestopportunity for understanding the role of recycled crustal components inoceanic island volcanism. In particular, this research will aid inconstraining the processes and source components which create a geochemicalendmember of Hawaiian shield lavas.

地面火山与三种不同的构造背景有关。 两种环境与板块边界有关，即板块辐散和会聚区，第三种环境与板内火山作用有关，这两种环境下喷发的岩浆地球化学特征有明显差异。 在这项研究中，我们的目标是了解决定夏威夷熔岩地球化学特征的来源和过程。 这个端元很有意义，因为它可能部分代表了洋壳在俯冲带俯冲到地幔深处的结果。方法是确定这两个地盾不同相对年龄熔岩中常量和微量元素的丰度以及O、Sr、Nd、Pb、Hf和Os的同位素比值。 对于Koolau，待研究的样品来自最近钻探的岩心，该岩心穿透屏蔽层的深度比以前研究的地表暴露样品更深，年龄更大。对于Kahoolawe，尚未进行深入研究，样品将来自屏蔽层的几个地层剖面。 主要目的是了解造成这些岩浆的源成分，因此重点是评价高度不相容元素丰度之间的相关性，例如，Ba/Th、Ce/Pb和La/Nb等同位素比值。 这些地球化学特征将用电感耦合等离子体质谱和热电离质谱等分析设备来确定。由于夏威夷火山的大洋板块背景、相对简单的矿物学和丰富的互补研究，夏威夷火山为理解大洋岛屿火山作用中再循环地壳成分的作用提供了最佳的条件。 特别是，这项研究将有助于inconstrained的过程和源组件，创造一个geochemicalendmember夏威夷盾熔岩。