Magma reservoir evolution at a slow-spreading mid-ocean ridge

缓慢扩张的洋中脊的岩浆储层演化

• 批准号: NE/X019098/1
• 负责人: Cornelis Lissenberg
• 金额: $ 3.49万
• 依托单位: CARDIFF UNIVERSITY
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FX019098%2F1
• 关键词: Magma; reservoir; evolution; slow; spreading

Mid-ocean ridges form the largest magmatic system on Earth. Oceanic crust is formed when the upper mantle wells up and partially melts in response to plate separation. The melts thus formed rise upwards, forming the magma reservoirs of the lower oceanic crust, and erupt to form mid-ocean ridge basalts.The nature of magma reservoirs at mid-ocean ridges remains poorly constrained. Traditional models hold that they are bodies of pure melt in which magma evolution is controlled by fractional crystallisation. This model is increasingly challenged, and a new paradigm in which magma reservoirs are comprised of crystal mush - a mixture of melt and crystals - has now emerged. Melt transport and evolution in mush reservoirs may be controlled by porous flow, which has fundamental implications for the eruption dynamics and geochemical signatures of mid-ocean ridge basalts.This project will reconstruct the architecture and evolution of magma reservoirs at the Mid-Atlantic Ridge. It will capitalise on core that will be recovered from Hole U1309D (30 degrees N) by scientific ocean drilling. Previous drilling at this location has shown that this section contains an excellent record of fossilised magma reservoirs beneath a slow-spreading mid-ocean ridge.This project will integrate core observations with state-of-the-art element mapping and measurements of mineral major- and trace elements to address three challenges:1) The size of magma reservoirs;2) The melt composition and evolution within these reservoirs;3) The thermal histories of the reservoirs.Together, these different components will enable a test of the different end member models for reservoir architecture and melt transport. The outcome is a rigorous assessment of the nature and evolution of magma reservoirs beneath the Mid-Atlantic Ridge, with implications for magma evolution of oceanic basalts, which may serve as a template for mafic igneous systems generally.

中海脊构成地球上最大的岩浆系统。当上地幔孔向上并部分融化时，会形成海洋壳。因此，融化形成向上升起，形成了下海壳的岩浆储层，并爆发形成了海洋山脊中部。中山脊中岩浆储层的性质仍然受到良好的约束。传统模型认为它们是纯熔体的体，其中岩浆进化是由分数结晶控制的。该模型越来越挑战，并且岩浆储层由晶体糊和晶体的混合物组成的新范式现已出现。蘑菇储层中的熔体传输和进化可以由多孔流控制，这对中源山脊的喷发动力和地球化学特征具有根本性的影响。该项目将重建中型山脊的岩浆储层的建筑和进化。它将利用科学钻孔从孔U1309D（30摄氏度）中回收的核心。以前在此地点进行的钻探表明，本节包含在缓慢扩张的中山山脊下面的化石岩浆储层的出色记录。本项目将将核心观察与最先进的元素映射和矿物质的矿物质和痕量测量的测量结合在一起，以解决三个挑战：1）在岩浆储存中; 2）均置换; 2）梅尔特; 2）梅尔特; 2）梅尔特; 2）梅尔特; 2）储层的历史。结果是对中大西洋山脊下岩浆储层的性质和演变的严格评估，对海洋玄武岩的岩浆演化有影响，这可以用作通常通常的模板。