U-Th-Pb, Nd and Hf isotopic investigation of a complete in situ section of upper oceanic crust formed at a superfast spreading ridge (IODP Site 1256D)

对超快扩张脊形成的上洋地壳的完整原位剖面进行 U-Th-Pb、Nd 和 Hf 同位素研究（IODP 站点 1256D）

• 批准号: 28422929
• 负责人: Professor Dr. Kaj Hoernle
• 金额: --
• 依托单位: Forschungseinheit Magmatische und Hydrothermale Systeme
• 依托单位国家: 德国
• 项目类别: Infrastructure Priority Programmes
• 财政年份: 2006
• 资助国家: 德国
• 起止时间: 2005-12-31 至 2009-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/28422929?language=en
• 关键词: Th; Pb; Nd; Hf; isotopic

We propose the systematic determination of high-resolution Pb isotopic data and U, Th and Pb concentrations, as well as Nd and Hf isotopic compositions of a complete in situ section of oceanic crust (extrusive lavas, sheeted dikes, gabbros) drilled during IODP Exp. 309 and 312 (Site 1256D). Newly formed oceanic crust undergoes extensive chemical exchange with seawater during hydrothermal circulation processes and subsequent low-temperature alteration. This interaction influences the chemistry of the oceans, the oceanic crust and, through subduction, the composition of the upper mantle and eventually contributes to the characteristic signatures in mantle plumes by crustal recycling. A complete understanding of these chemical interactions depends on knowing the elemental fluxes between the oceans and the entire ocean crust section. Little information, however, presently exists on the heterogeneity of hydrothermal alteration at different crustal depths. The results of this project will allow us to assess the impact of high- and low-temperature alteration on the Pb isotopic budget of the oceanic crust.

我们建议系统测定 IODP 实验期间钻探的完整原位洋壳剖面（喷出熔岩、片状岩脉、辉长岩）的高分辨率 Pb 同位素数据和 U、Th 和 Pb 浓度，以及 Nd 和 Hf 同位素组成。 。 309 和 312（站点 1256D）。新形成的洋壳在热液循环过程和随后的低温蚀变过程中与海水进行广泛的化学交换。这种相互作用影响海洋、洋壳的化学成分，并通过俯冲影响上地幔的组成，并最终通过地壳循环形成地幔羽流的特征特征。对这些化学相互作用的完整理解取决于了解海洋和整个洋壳部分之间的元素通量。然而，目前关于不同地壳深度热液蚀变的异质性的信息很少。该项目的结果将使我们能够评估高温和低温变化对洋壳铅同位素预算的影响。