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

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地壳的60%。与空中火山不同的是，MOR火山活动隐藏在几公里的水下，使其过程在很大程度上是未知的。对于许多MORs来说，这种火山作用形成了轴向火山脊（avr），宽几公里，长几十公里，在其演化过程中表现为幕式或周期性。尽管产生avr的过程、它们的偶发性、渗出率以及与地幔融水提取的联系是许多猜测的焦点，但实际上很少有足够的细节来揭示它们的演变。这在很大程度上是因为我们还没有足够的工具来研究火山结构，对火山地层学进行采样，或者在所需的精细尺度上确定喷发单元之间的年龄关系。近年来，新一代潜水仪器已经开发出来，现在使我们能够以亚米分辨率成像，并以类似的精度收集样本，从而直接解决AVR的成因。年代测定技术的最新发展，加上地球化学分析精度的提高，现在为检验许多描述摩尔火山作用的模型提供了手段。在这里，我们提出了一项详细的研究，利用目前可用的高分辨率工具来解开MOR火山作用的复杂过程。我们将使用测量地球磁场强度的变化、沉积物堆积的变化和年轻玄武岩的放射性中心测年（包括新开发的铀系列测年）来估计精确的年龄。这项研究的复杂性需要不同实验室之间和不同大陆之间的合作。把我们的资源集中在这个国际项目上。我们的研究将对时间尺度、喷发速率、熔岩量以及火山与其下地幔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个关键组成部分，以及它与整个地球演化的关系，这些见解是必不可少的。

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.