The geochemical and isotopic (Li, B, Sr, O, C) compositions of veins from altered oceanic lithosphere at Atlantis Massif: Implications for interactions with seawater

亚特兰蒂斯地块改变的海洋岩石圈脉体的地球化学和同位素（Li、B、Sr、O、C）组成：与海水相互作用的影响

• 批准号: 28833161
• 负责人: Professor Dr. Wolfgang Bach
• 金额: --
• 依托单位: Fachgebiet Petrologie der Ozeankruste
• 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 2008-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/28833161?language=en
• 关键词: geochemical; isotopic; Li; Sr; compositions

Subseafloor water-rock interactions during the alteration of oceanic lithosphere are recorded by different stages of carbonate and anhydrite veining. We propose to carry out a comprehensive geochemical study of carbonate and anhydrite veins hosted in upper mantle sections comprised of gabbroic rocks and serpentinized peridotite from slow spreading Mid-ocean Ridges (ODP/IODP Legs 153, 209, 304/305). Altered mafic and ultramafic lithologies are now recognized as abundant seafloor rocks. Hence, the understanding of chemical exchange between lithosphere and seawater during sub-seafloor alteration in these settings is an important issue in assessing geochemical cycles. Trace element abundances and isotope (Li, B, C, O, Sr) compositions will be used to gain insights in the evolution of seawater circulation in basement during exhumation and uplift of lithospheric mantle in oceanic core complexes. Coupling these data with estimates of formation temperatures and ages of veins will allow the reconstruction of reaction pathways and rates. Such data are required for examinations of exchange budgets between oceanic lithosphere and the oceans. In addition, temperature and age information on vein formation will help unravel the dynamics of late-stage accretion and uplift of lithosphere along slow spreading ridges. Data from carbonate veins of ODP Leg 209 demonstrate how trace element abundances, Li, O, Sr isotope compositions, and radiometric age determinations can be combined to decipher the late-stage history of oceanic lithosphere exhumation and interactions with seawater.

碳酸盐岩脉和硬石膏脉记录了大洋岩石圈蚀变过程中海底水-岩相互作用的不同阶段。我们建议对来自缓慢扩张的大洋中脊（ODP/IODP Legs 153、209、304/305）的辉长岩和蛇纹石化橄榄岩组成的上地幔部分中的碳酸盐和硬石膏脉进行全面的地球化学研究。蚀变镁铁质和超镁铁质岩石现在被认为是丰富的海底岩石。因此，了解在这些背景下的海底蚀变过程中岩石圈和海水之间的化学交换是评估地球化学循环的一个重要问题。微量元素丰度和同位素（Li，B，C，O，Sr）组成将被用来了解大洋核杂岩岩石圈地幔折返和隆升过程中基底海水循环的演化。将这些数据与地层温度和矿脉年龄的估计相结合，将允许重建反应途径和速率。研究大洋岩石圈与海洋之间的交换收支需要这些数据。此外，矿脉形成的温度和年龄信息将有助于揭示岩石圈沿着缓慢扩张脊的晚期增生和隆升的动力学。ODP Leg 209碳酸盐岩脉的数据展示了如何将微量元素丰度、Li、O、Sr同位素组成和放射性年龄测定结合起来，以破译海洋岩石圈折返和与海水相互作用的晚期历史。