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.

FreyEAR-0105557陆地火山与三种不同的构造环境有关。 两个与板块边界有关，即板块辐散和汇聚区域，第三个是板内火山作用。在这些不同环境中喷发的岩浆的地球化学特征存在显着差异。 在这项拟议的研究中，目标是了解决定夏威夷熔岩地球化学特征的来源和过程。 这个端元非常有趣，因为它可能部分代表了俯冲带洋壳深入地幔的后果。该方法将确定主量元素和微量元素的丰度以及 O、Sr、Nd、Pb、Hf 和 Os 的同位素比率在这两个盾牌的不同相对年龄的熔岩中。 对于 Koolau，要研究的样本来自最近钻探的岩心，与之前研究的地表暴露样本相比，该岩心穿透地盾的深度更大，年龄也更老。对于尚未深入研究的 Kahoolawe，样本将来自地盾上的几个地层剖面。 主要目标是了解这些岩浆的来源成分；因此，重点将放在评估高度不相容元素（例如 Ba/Th、Ce/Pb 和 La/Nb）丰度比与同位素比之间的相关性。 这些地球化学特征将使用感应耦合等离子体质谱和热电离质谱等分析设施来确定。由于其海洋板块背景、相对简单的矿物学和丰富的互补研究，夏威夷火山为了解大洋岛再循环地壳成分的作用提供了最佳机会火山作用。 特别是，这项研究将有助于限制产生夏威夷地盾熔岩地球化学端元的过程和源成分。