The geochemical evolution of Hawaiian magmatism: ODP Leg 197 drilling of the Emperor Seamounts

夏威夷岩浆作用的地球化学演化：皇帝海山 ODP Leg 197 钻探

• 批准号: 5339418
• 负责人: Professor Dr. Albrecht W. Hofmann
• 金额: --
• 依托单位: GEOMAR Helmholtz-Zentrum für Ozeanforschung Kiel
• 依托单位国家: 德国
• 项目类别: Infrastructure Priority Programmes
• 财政年份: 2001
• 资助国家: 德国
• 起止时间: 2000-12-31 至 2004-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/5339418?language=en
• 关键词: geochemical; evolution; Hawaiian; magmatism; ODP

Long-lived, intra-plate (hotspot) magmatism, such as occurs on Hawaii, is thought to be the surface expression of mantle plumes: Columns of relatively hot material rising from deeper in the mantle. Geochemical studies of hotspot magmatism can thus give insights into the structure and composition of the Earth's deep interir, which cannot be directly sampled. We plan to carry out a geochemical and isotopic study of samples of volcanic rocks from the Emperor Seamounts, in the northern Pacific Ocean, which will be recovered by drilling on ODP Leg 197 (Juli - August, 2001). The Emperor Seamounts were creted when the Pacific Plate passed over the Hawaiian hotspot, and the samples to be analysed provide a unique, 40 Ma record (from 85 to 45 Ma ago) of the geochemistry of this hotspot. This study will document the geochemical evolution of Hawaiian magmatism over this period. Specific questions to be addressed are, (a) the nature, scale and origin of mantle heterogeneity in mantle plumes, and the temporal evolution of plume composition; (b) the influence of shallow-level processes such as lithospheric contamination, melting and spreading ridge interaction on the composition of intraplate lavas; (c) the origin of shield and post-shield intra-plate magmatism.

长期存在的板块内（热点）岩浆活动，如发生在夏威夷的岩浆活动，被认为是地幔柱的表面表现：相对较热的物质柱从地幔深处上升。因此，对热点岩浆活动的地球化学研究可以深入了解地球深部的结构和组成，而这些都是无法直接采样的。我们计划对来自北太平洋皇帝海山的火山岩样本进行地球化学和同位素研究，这些样本将通过钻探ODP Leg 197（2001年7月至8月）进行回收。皇帝海山是在太平洋板块经过夏威夷热点时形成的，要分析的样本提供了这个热点的独特的40 Ma地球化学记录（从85到45 Ma以前）。这项研究将记录这一时期夏威夷岩浆活动的地球化学演化。需要解决的具体问题有：(a)地幔柱中地幔非均质性的性质、规模和起源，以及地幔柱组成的时间演化；(b)岩石圈污染、熔融和伸展脊相互作用等浅层过程对板内熔岩组成的影响；(c)盾构和后盾构板块内岩浆活动的成因。