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Investigating the influence of lithology and water depth on the composition and distribution of sulphides at the worlds deepest known vent sites.

研究岩性和水深对世界上已知最深喷口处硫化物成分和分布的影响。

基本信息

批准号：
NE/I01442X/1
负责人：
Bramley Murton
金额：
$ 37.21万
依托单位：
NATIONAL OCEANOGRAPHY CENTRE
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2011
资助国家：
英国
起止时间：
2011 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FI01442X%2F1
关键词：
Investigating influence lithology water depth

项目摘要

The start of the Age of Metal marked a step-change for mankind. Today, our entire technological society is dependent on metals. But it all started with copper. One of the main sources of this metal in the ancient world was Cyprus in the eastern Mediterranean. Cyprus is named after the Greek word for copper. The island's secret was the Troodos ophiolte, an ancient fragment of oceanic crust that was uplifted to form a mountain range. Here, eighty six million years ago, high-temperature hydrothermal vents deposited large mineral ore bodies on the seafloor. Below the seabed, these were rich in copper minerals, deposited by the hot vent fluids as they mixed with cold seawater. Today, modern hydrothermal vents, their ore deposits, and exotic animals are well known as striking examples of geology in action. But we know relatively little about what determines the distribution and composition of the ore deposits. We think that vent fluids become rich in valuable base metals deep beneath mid-ocean ridges, where pressures are 5000 atmospheres and temperatures reach ~500 degrees Celsius. Under these conditions, seawater is supercritical (i.e. the vapour phase behaves like a fluid) and is so reactive that it can easily dissolve rocks. We also think that the composition of those dissolving rocks is important. Different rocks have different metals in them and this affects the composition and value of the ore deposits. But until now, it has been impossible to sample hydrothermal systems under these pressure and temperature conditions. In April 2010, we made the extraordinary discovery of hydrothermal activity in the deepest mid-ocean ridge on Earth. Within the Cayman Trough, deep beneath the Caribbean Sea, we found vents at 5000m gushing out supercritical fluids at nearly 500 degrees Celsius. These are the hottest ever found, and are close to the conditions normally found where seawater meets magma chambers deep below the seafloor. With another expedition already scheduled for 2012, we have a unique opportunity to use this natural laboratory to test predictions about the distribution and composition of ore deposits formed from such high-temperature supercritical fluids. The significance of this work is multi-fold. Economically, we can apply the knowledge gained from this unique study to predict other, more accessible ore deposits on land and at sea. Already, deep-sea extraction companies are starting to explore seafloor ore deposits. The information we gather from this study will help predict the future viability of these deposits. Our new data will also help inform governments and NGOs (e.g. the United Nations International Seabed Authority) of how to protect these sites and ensure that only sustainable exploration is ever planned. Scientifically, we will gain a new understanding of the role of pressure, temperature and rock composition in the formation of ore deposits. We will also revise our estimates of the exchange of heat and fluids between the ocean and seafloor. This exchange helps explain why the sea is salty and the Earth's climate has been in balance. Our exciting work, in such an extreme environment, will continue to engage the public's imagination and help promote science and technology to tomorrow's generation.

金属时代的开始标志着人类的一大变革。今天，我们整个技术社会都依赖于金属。但这一切都始于铜。古代世界这种金属的主要来源之一是地中海东部的塞浦路斯。塞浦路斯是根据希腊语中铜的意思命名的。这座岛的秘密是奥多斯岛，这是一块古老的洋壳碎片，被隆起形成了山脉。在这里，8600万年前，高温热液喷口在海底沉积了巨大的矿体。在海床下面，它们含有丰富的铜矿物，由热的喷口流体与冷海水混合时沉积下来。今天，现代热液喷口、它们的矿藏和外来动物都是众所周知的地质学作用的显著例子。但我们对是什么决定了矿床的分布和组成知之甚少。我们认为，喷口流体在大洋中脊深处变得富含有价值的贱金属，那里的压力为5000大气压，温度达到~500摄氏度。在这些条件下，海水是超临界的(即蒸气相表现得像流体)，而且非常活泼，很容易溶解岩石。我们还认为，这些溶解岩石的成分很重要。不同的岩石中含有不同的金属，这就影响了矿床的成分和价值。但到目前为止，还不可能在这种压力和温度条件下对热液系统进行采样。2010年4月，我们在地球上最深的大洋中脊发现了非凡的热液活动。在加勒比海深处的开曼海槽内，我们发现5000米的喷口在近500摄氏度的温度下喷发出超临界流体。这是迄今发现的最热的，接近通常情况下海水与海底深处的岩浆室相遇的条件。随着另一次探险计划于2012年进行，我们有一个独特的机会，可以利用这个天然实验室来测试对这种高温超临界流体形成的矿藏的分布和组成的预测。这项工作的意义是多方面的。在经济上，我们可以应用从这项独特的研究中获得的知识来预测陆地和海洋上其他更容易获得的矿藏。深海开采公司已经开始勘探海底矿藏。我们从这项研究中收集的信息将有助于预测这些矿藏未来的生存能力。我们的新数据还将帮助政府和非政府组织(如联合国国际海底管理局)了解如何保护这些地点，并确保只规划可持续的勘探活动。科学地认识压力、温度、岩石成分在矿床形成中的作用。我们还将修订我们对海洋和海底之间的热量和流体交换的估计。这种交流有助于解释为什么海洋是咸的，而地球的气候一直是平衡的。我们令人兴奋的工作，在这样一个极端的环境中，将继续激发公众的想象力，并帮助向明天的一代推广科学技术。