Metallogeny of modern and ancient oceans

在海底火山中发现能沉积金属的热泉，尤其是发现它与化学合成生命的联系，是20世纪最引人注目的科学进步之一。世界上80%的活火山位于海洋中，火山和热液活动现在被认为在海洋环境的硫、碳和金属循环中起着关键作用。然而，关于海底热液系统的多样性、不同来源的金属通量以及热液喷口金属流入海洋的历史，仍然存在重要问题。海底火山活动在地球的古代海洋中更为普遍，相关的热液活动是世界上许多最大和最有价值的矿藏的原因。 然而，控制这些资源分布的基本地球动力学因素尚未完全了解。为了解决其中一些问题，我们正在参加一项国际努力，以探索和记录海洋中各种不同火山和构造环境中的热液活动。研究的具体目标是：㈠查明现代海底热液系统中金属的不同来源、汇和迁移途径，㈡量化不同热液来源的金属自然流入海洋的量，包括具有潜在持久远场环境影响的金属，㈢将目前的金属通量与过去海底金属积聚的地质记录进行比较; ㈣改进现代和古代火山岩的金属清单模型。这些目标将通过一项海底测绘和取样方案、相关的实验室研究以及关于古代矿床的实地工作来实现。这项研究的数据将有助于建立地球海洋地球化学演变的新模型，并将直接实际应用于陆地矿产资源的勘探。

The discovery of metal-depositing hot springs at volcanoes on the seafloor, and especially the link to chemosynthetic life, was one of the most compelling scientific advances of the 20th century. 80% of the world's active volcanoes occur in the oceans, and the volcanic and hydrothermal activity is now recognized as having a critical role in the sulfur, carbon and metal cycles of the marine environment. However, important questions remain about the diversity of seafloor hydrothermal systems, the flux of metals from different sources, and the history of metal loading to oceans from hydrothermal vents. Seafloor volcanism was even more prevalent in Earth's ancient oceans, and the associated hydrothermal activity was responsible for many of the world's largest and most valuable mineral deposits. However, the underlying geodynamic factors controlling the distribution of these resources are not fully understood. To address some of these questions, we are participating in an international effort to explore and document hydrothermal activity in a variety of different volcanic and tectonic settings in the oceans. The specific objectives of the research are: (i) to identify different sources, sinks and transport pathways for metals in modern seafloor hydrothermal systems, (ii) to quantify the natural loading of metals to the oceans from different hydrothermal sources, including those metals with potentially lasting far-field environmental significance, (iii) to compare present-day fluxes of metals with the geological record of past metal accumulations on the seafloor, and (iv) to improve models of the metal inventory of both modern and ancient volcanic terranes. These objectives will be achieved through a program of seafloor mapping and sampling, related laboratory studies, and field work on ancient ore deposits. Data from this research will contribute to new models of the geochemical evolution of Earth's oceans and will have direct practical application in the exploration for land-based mineral resources.