Magmatic evolution of an oceanic island arc – The New Hebrides case

大洋岛弧的岩浆演化——新赫布里底群岛案例

• 批准号: 428591405
• 负责人: Professor Dr. Karsten Matthias Haase
• 金额: --
• 依托单位: GeoZentrum Nordbayern
• 依托单位国家: 德国
• 项目类别: Infrastructure Priority Programmes
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/428591405?language=en
• 关键词: Magmatic; evolution; oceanic; island; arc

The magmatic evolution of oceanic island arcs and their potential implications for subduction initiation received much attention recently with the IODP expeditions 350, 351, and 352 in the Izu-Bonin-Mariana (IBM) arc, forearc and rear-arc dedicated to test existing models. Most of the ideas on subduction initiation are thus based on the IBM arc but it is unknown whether these can be applied also to other oceanic island arcs. The New Hebrides island arc (NHIA) is one of the youngest arcs on Earth and formed by subduction initiation following polarity reversal of the subducting plate after the collision of the Ontong Java Plateau some 15 million years ago. Leg 134 of the ODP drilled seven cores with lengths of up to 1100 m in the New Hebrides forearc and backarc and recovered magmatic rocks samples as well as ash layers ranging to the Mid-Miocene. We suggest to re-analyse the rock samples from this ODP Leg as well as other poorly analysed submarine samples from dive and dredge cruises in order to compare the magmatic evolution of the NHIA to the IBM. Additionally, we propose sampling of the central NHIA to establish the magmatic evolution of the old island arc crust to 20 Ma. The new data set will also provide insights into the magma evolution of the NHIA following the subduction of the d’Entrecasteaux island arc that occurred some 2 Ma ago. Our proposed project has important implications for the global understanding of subduction processes and the associated magma formation in the upper mantle.

大洋岛弧的岩浆演化及其对俯冲开始的潜在影响最近引起了人们的极大关注，IODP探险队350、351和352次在Izu-Bonin-Mariana(IBM)弧、弧前和弧后专门测试现有模型。因此，大多数关于俯冲开始的想法都是基于IBM弧，但尚不清楚这些想法是否也适用于其他大洋岛弧。新赫布里底斯岛弧(NHIA)是地球上最年轻的岛弧之一，是约1500万年前安通爪哇高原碰撞后俯冲板块发生极性反转后俯冲引发的。ODP134号钻探在新赫布里底斯弧前和弧后钻探了长达1100米的7个岩芯，并发现了岩浆岩样品以及从中中新世到中新世的火山灰层。我们建议重新分析这段ODP线的岩石样品，以及潜水和挖潜巡航中分析较差的其他海底样品，以便将NHIA和IBM的岩浆演化进行比较。此外，我们还建议对NHIA中部进行采样，以确定古老岛弧地壳的岩浆演化至20 Ma。新的数据集还将提供对大约2 Ma前发生的d‘Entrecasteaux岛弧俯冲后NHIA的岩浆演化的洞察。我们提出的项目对于全球理解俯冲过程和相关的上地幔岩浆形成具有重要意义。