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

对深海橄榄岩的研究有可能揭示地球非均质地幔的组成。2016年7月，在M128号RV METEOR巡航期间，在亚速尔高原南缘回收了这种深海橄榄岩。这些岩石代表了在北大西洋中部这一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，这些地幔样本对这种地球动力学背景具有重要的限制。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海洋岩石圈的橄榄岩，还是它们代表了流出的亚速尔地幔柱的残余地幔岩石。后者被认为是亚速尔群岛上熔岩喷发的最终地幔来源。在拟议的研究中将获得新的化学和同位素数据。结果将与亚速尔群岛和附近MAR的现有火山岩文献数据进行对比，表明它们起源于地球化学上不同的地幔源。由于这些明确确定的MAR和亚速尔群岛地幔之间的地球化学和同位素差异，拟议的研究将为EAFZ暴露地幔的性质和起源提供关键限制。

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.