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.

最近，IODP在伊豆-波宁-马里亚纳（IBM）弧、弧前和弧后进行了350、351和352次考察，以测试现有模型，海洋岛弧的岩浆演化及其对俯冲起始的潜在影响受到了广泛关注。因此，大多数关于俯冲起始的想法都是基于IBM弧，但这些想法是否也适用于其他海洋岛弧尚不清楚。新赫布里底岛弧（New Hebrides island arc， NHIA）是地球上最年轻的岛弧之一，是由俯冲板块在1500万年前与Ontong爪哇高原碰撞后发生极性反转后的俯冲引发形成的。ODP的134号腿在新赫布里底岛弧前和弧后钻了7个长度达1100米的岩心，并回收了岩浆岩样本以及中中新世的火山灰层。我们建议重新分析来自ODP Leg的岩石样本以及其他来自潜水和疏浚巡航的分析不佳的潜艇样本，以便将NHIA的岩浆演化与IBM进行比较。此外，我们建议对NHIA中部进行采样，以确定古岛弧地壳到20 Ma的岩浆演化。新的数据集还将提供关于大约2 Ma前d 'Entrecasteaux岛弧俯冲后NHIA岩浆演化的见解。我们提出的项目对全球了解上地幔的俯冲过程和相关岩浆形成具有重要意义。