Structure and evolution of Axial Volcanic Ridges: Constraining the architecture, chronology and evolution of ocean ridge magmatism.

大洋中脊(MORS)是地球上规模最大的火山活动的所在地，其产物产生了地球表面60%的地壳。与其空中对应的火山不同，莫尔火山隐藏在几公里深的水下，因此其过程基本上是未知的。对于许多MORS来说，这种火山活动形成了几公里宽、几十公里长的轴向火山脊(AVR)，它们的演化似乎是间歇性的或周期性的。尽管产生AVR的过程、它们的偶然性、渗漏率以及与从地幔中熔融提取的联系是许多猜测的焦点，但实际上人们对它们的演化细节知之甚少。这在很大程度上是因为我们没有能够研究火山建筑、采样火山地层或确定所需精细规模的喷发单元之间年龄关系的工具。近年来，新一代潜水仪器已经开发出来，现在使我们能够成像到亚米级分辨率，并采集类似精度的样品，从而直接探讨AVR的成因。测年技术的最新发展，加上地球化学分析精度的提高，现在提供了测试许多描述莫尔火山作用的模型的手段。在这里，我们建议使用目前可用的高分辨率工具进行一项详细的研究，以揭开莫尔火山活动的复杂过程。我们将利用对地球磁场强度变化、沉积物堆积变化的测量，以及年轻玄武岩的辐射定年(包括新开发的铀系列定年)来估计准确的年龄。这项研究的复杂性需要跨不同实验室和不同大陆之间的合作。通过将我们的资源集中在这一国际计划中。我们的研究将对火山的时间尺度、喷发率、熔岩量以及火山与其下伏地幔来源之间的相互作用产生新的见解。如果我们要了解地球系统的这一关键组成部分，以及它与整个地球进化的关系，这些洞察是必不可少的。

Mid-ocean ridges (MORs) are the loci of the most voluminous volcanism on our planet, the products of which have generated 60% of the Earth's surface crust. Unlike its sub-aerial counterpart, MOR volcanism is hidden from view beneath several kilometres of water, leaving the processes largely unknown. For many MORs, this volcanism forms axial volcanic ridges (AVRs), a few kilometres wide and tens of kilometres long, which appear episodic or cyclic in their evolution. Although the processes that generate AVRs, their episodicity, effusion rates and links to melt extraction from the Earth's mantle are the focus of much speculation, little is actually known in sufficient detail to unravel their evolution. This is largely because we have not had the tools capable of studying volcanic architecture, sampling volcanic stratigraphy or determining age relationships between erupted units at the fine scale required. In recent years a new generation of submersible instruments has been developed that now allow us to image to sub-metre resolutions and to collect samples to similar precision, and hence to address AVR genesis directly. Recent developments in dating techniques, coupled with improvements in the precision of geochemical analyses, are now providing the means to test many of the models describing MOR volcanism. Here, we propose a detailed study using the high-resolution tools now available to unravel the complex processes of MOR volcanism. We will use measurements of the variation of the Earth's magnetic field strength, variations in sediment accumulation, and radiomentric dating (including newly-developed uranium series dating) of young basalts, to estimate precise ages. The complexity of the study requires collaboration across different laboratories and between different continents. By pooling our resources in this international programme. our study will yield new insights into the time scales, eruption rates, lava volumes and interaction between the volcanoes and their underlying mantle source. These insights are essential if we are to understand this key component of the Earth System - and hence its relationship to Earth evolution as a whole.