Seafloor hydrothermal processes and deposits

海底热液过程和沉积物

• 批准号: 7069-2006
• 负责人: Scott, Steven
• 金额: $ 4.34万
• 依托单位: University of Toronto
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2008
• 资助国家: 加拿大
• 起止时间: 2008-01-01 至 2009-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=389464
• 关键词: Seafloor; hydrothermal; processes; deposits

This research aims to solve the mystery of how base and precious metal ore bodies are formed in volcanic rocks. Some of these deposits contain in excess of 100 million tons of ore. These are rare but very desirable because they represent the most cost effective means of producing metals such as zinc, copper, lead, silver and gold that are essential to modern society. Canadian examples such as Kidd Creek in Ontario and Brunswick #12 in New Brunswick would completely fill 10 Toronto Skydomes. Another aspect of my research is to determine the dispersal patterns of contaminants in sediments resulting from the ore-forming process. These contaminants (various metals, barium and arsenic) may provide vectors towards ores. Yet another is to understand the role of micro-organisms in the formation or iron and other base metal ores through the process of "biomineralization". It is generally considered that ore bodies now on land formed in ancient seas where seawater circulating through hot volcanic rocks became heated to 350°C (hot enough to melt lead). This hot sea water leached metals from the rocks and precipitated them as minerals where it discharged onto the sea floor. These metal-rich hot springs, known as "black smokers" because they resemble a dirty industrial process, are found in many regions of the world's oceans but none of them are accumulating metals in anywhere near the amounts of a Kidd Creek. From where, then, did all the metals in Kidd Creek come? The answer may be from fluids and gases, a so-called "magmatic fluid", issuing directly from the molten rock ("magma") that produces lavas from the depths of the Earth. As magmas rise within the seafloor crust, they cool and give off gases, mostly carbon dioxide and water. Some of these gases are trapped as tiny bubbles within the lavas. Careful work on such rocks from the sea bed off eastern Papua New Guinea with high resolution microscopes and micro analytical instruments has shown that accidentally trapped magmatic fluids are extremely rich in metals, many times more that the hot sea water of the black smokers.

这项研究的目的是解开火山岩中贱金属矿体和贵金属矿体是如何形成的谜团。其中一些矿床的矿石储量超过1亿吨。这些矿床很稀有，但却非常令人向往，因为它们是生产锌、铜、铅、银和金等现代社会必不可少的金属的最具成本效益的方法。加拿大的例子，如安大略省的基德溪和新不伦瑞克省的不伦瑞克12号，将完全填满10个多伦多天空穹顶。我研究的另一个方面是确定成矿过程产生的沉积物中污染物的扩散模式。这些污染物（各种金属、钡和砷）可能为矿石提供载体。另一个是通过“生物矿化”过程了解微生物在铁和其他贱金属矿形成中的作用。人们普遍认为，现在陆地上的矿体是在古代海洋中形成的，在那里，流经热火山岩的海水被加热到350°C（足以熔化铅）。这种热海水从岩石中滤出金属，并将其沉淀为矿物质，然后排放到海底。这些富含金属的温泉，被称为“黑烟”，因为它们像一个肮脏的工业过程，在世界上的许多海洋地区都有发现，但没有一个地方的金属积累量接近基德溪。那么，基德溪的所有金属都是从哪里来的呢？答案可能是流体和气体，一种所谓的“岩浆流体”，直接从地球深处产生熔岩的熔融岩石（“岩浆”）中释放出来。当岩浆在海底地壳中上升时，它们冷却并释放出气体，主要是二氧化碳和水。其中一些气体以微小气泡的形式被困在熔岩中。用高分辨率显微镜和微型分析仪器对巴布亚新几内亚东部海底的这些岩石进行了仔细研究，结果表明，意外捕获的岩浆流体中含有极其丰富的金属，比黑烟区热海水中的金属含量高出许多倍。