Geochemical Effects of Deep Subduction of Oceanic Crust: An Experimental Study of 4-20 GPa

洋壳深俯冲地球化学效应：4-20 GPa的实验研究

• 批准号: 9706517
• 负责人: Robert Rapp
• 金额: $ 7.14万
• 依托单位: SUNY at Stony Brook
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-07-01 至 1999-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9706517&HistoricalAwards=false
• 关键词: Geochemical; Effects; Deep; Subduction; Oceanic

9706517 Rapp This experimental study on the geochemical effects of deep subduction of the oceanic crust has two parts. The first aspect is to place experimental constraints on the linked processes of tonalite-trondhjemite granodiorite plutonism and cratonization. A series of multi-anvil experiments on hydrous natural basalts will be conducted in the pressure range 4-8 GPa at 900-1200oC, to complement existing experimental data at 1-3 GPa. Objectives include defining the wet basalt solidus in this range, determining the compositions of the phases in the hydrous melt-eclogite restite assemblage, and estimating the trace element mineral-melt partition coefficients in order to constrain the geochemical characteristics of eclogite residues of partial melting. The second aspect of the proposal aims to examine the geochemical changes oceanic crust undergoes as it subducts beyond the island arc regime into the transition zone, again by conducting phase equilibria experiments on hydrous basalt in the multi-anvil apparatus. This aspect will be addressed by defining the general phase relations for hydrous basalt in the P-T range 4-20 GPa and 900-1300oC, and then focusing on trace element systematics in garnet, clinopyroxene, and their solid solutions in natural basalt compositions as a function of pressure.

9706517 Rapp大洋地壳深俯冲地球化学效应的实验研究有两个部分。 第一个方面是对英云闪长岩-奥长花岗岩花岗闪长岩深成作用和花岗岩化的相互联系过程进行实验约束。 将对含水天然玄武岩进行一系列多砧实验，压力范围为4-8 GPa，温度为900- 1200 oC，以补充现有的1-3 GPa实验数据。 目的包括定义该范围内的湿玄武岩固相线，确定含水熔体-榴辉岩残余岩组合中的相组成，并估计微量元素矿物-熔体分配系数，以约束部分熔融榴辉岩残余物的地球化学特征。 该提案的第二个方面旨在再次通过在多砧装置中对含水玄武岩进行相平衡实验，研究洋壳在俯冲越过岛弧体系进入过渡区时所经历的地球化学变化。 这一方面将通过定义在P-T范围4-20 GPa和900- 1300 oC的含水玄武岩的一般相关系来解决，然后集中在天然玄武岩成分中的石榴石，单斜辉石及其固溶体中的微量元素系统学作为压力的函数。