Origin and nature of peridotites from the East-Azores Fracture Zone

东亚速尔群岛断裂带橄榄岩的起源和性质

• 批准号: 395839325
• 负责人: Dr. Felix Genske
• 金额: --
• 依托单位: Institut für Mineralogie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2018-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/395839325?language=en
• 关键词: Origin; nature; peridotites; East; Azores

Studies of abyssal peridotites have the potential to unravel the composition of Earths heterogeneous mantle. During cruise M128 with RV METEOR in July 2016, such abyssal peridotites were recovered from the southern margin of the Azores Plateau. These rocks represent the first mantle rocks recovered from this region in the central North-Atlantic. Due to their proximity to the volcanic Azores islands, these mantle samples hold important constraints about this geodynamic setting. The questions to be addressed during the proposed project concern the chemical and isotopic (Hf-Nd) composition of these key-samples. One question in particular is, if these rocks are peridotites from the oceanic lithosphere that existed prior to the formation of the Azores Plateau, or if they represent residual mantle rocks of the outflowing Azores mantle plume. The latter is thought to be the ultimate mantle source for the lavas erupted on the Azores islands. New chemical and isotopic data will be acquired in the proposed study. The results will be contrasted to existing literature data on volcanic rocks from the Azores islands and the nearby MAR, which show that they originate from geochemically different mantle sources. Owing to these clearly established geochemical and isotopic differences between the MAR and Azores mantle, the proposed study will provide key constraints on the nature and origin of the exposed mantle at the EAFZ.

对深海橄榄岩的研究有可能揭开地球非均质地幔的组成。2016年7月，在搭载RV流星的M128巡航期间，在亚速尔高原南缘发现了这样的深海橄榄岩。这些岩石代表了在北大西洋中部这个地区发现的第一批地幔岩石。由于它们靠近火山亚速尔群岛，这些地幔样本对地球动力学环境有重要的制约作用。拟议项目期间要解决的问题涉及这些关键样品的化学和同位素(Hf-Nd)组成。一个特别的问题是，这些岩石是来自亚速尔高原形成之前存在的大洋岩石圈的橄榄岩，还是它们是流出的亚速尔地幔热柱的残余地幔岩石。后者被认为是亚速尔群岛上喷发的熔岩的最终地幔来源。拟议的研究将获得新的化学和同位素数据。这一结果将与现有文献中关于亚速尔群岛和邻近MAR的火山岩的数据进行对比，后者表明它们来自不同的地幔来源。由于MAR和亚速尔群岛地幔之间存在这些明确的地球化学和同位素差异，拟议的研究将对EAFZ暴露的地幔的性质和来源提供关键限制。