Laboratory investigations and theoretical considerations on the electrical properties of seafloor massive sulfides

海底块状硫化物电特性的实验室研究和理论思考

• 批准号: 326799290
• 负责人: Professor Dr. Andreas Hördt
• 金额: --
• 依托单位: Institut für Geophysik und Extraterrestrische Physik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2016
• 资助国家: 德国
• 起止时间: 2015-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/326799290?language=en
• 关键词: Laboratory; investigations; theoretical; considerations; electrical

In order to satisfy future global demands for metals, there is an increasing interest in deep-sea mining. Seafloor massive sulfides (SMS) are considered an important marine metal resource. They are generated in regions of submarine volcanic activity, in particular mid-ocean ridges. Since underwater mining is difficult and expensive, a careful exploration and characterisation of seafloor deposits is essential. Electrical methods, and in particular induced polarization, are considered to play a key role, because they determine the electrical conductivity of the rocks, which depends on mineral content. Unlike for continental ores, where a wealth of data exists, the electrical properties of SMS are poorly known. Seafloor samples are rare and difficult to obtain, and only a small number of studies exists. Results obtained for continental sulfides cannot easily be transferred to seafloor conditions, because the marine fluids are considerably more saline, and the rock chemistry and texture may differ. In this project, we measure the frequency-dependent electrical properties of a large number of SMS samples from several worldwide locations, including deposits in the Atlantic, Pacific and Mediterranean. The results will be analysed in the context of mineralogical data, in order to identify potential relationships between electrical parameters and mineral content, that will constitute a basis for future exploration programs. The measurements will be preceded by methodological studies to define the optimum procedure to measure electrical properties of samples of irregular shapes. The SMS samples are valuable and it is generally not desired to destroy them, such that standard methods using cylindrical plugs cannot be applied to all samples. The data interpretation will be supported by extensive theoretical considerations, in order to obtain a fundamental understanding of the physical processes that control the electrical impedance of mineralized rock. Existing theories exclusively assume that the minerals are disseminated, whereas experimental evidence suggests that connected veins have a huge influence on electrical conductivity and cannot be neglected. Our theoretical advancements will combine existing models of the electrochemistry with new methods recently developed for unmineralized sediments.

为了满足未来全球对金属的需求，人们对深海采矿的兴趣日益浓厚。海底块状硫化物（SMS）被认为是重要的海洋金属资源。它们产生于海底火山活动区域，特别是洋中脊。由于水下采矿既困难又昂贵，因此对海底矿床进行仔细勘探和表征至关重要。电方法，特别是诱发极化，被认为发挥着关键作用，因为它们决定了岩石的电导率，而岩石的电导率取决于矿物含量。与存在大量数据的大陆矿石不同，SMS 的电特性人们知之甚少。海底样本稀有且难以获取，并且只有少量的研究存在。大陆硫化物获得的结果不能轻易转移到海底条件，因为海洋流体的含盐量要高得多，并且岩石化学和质地可能有所不同。在该项目中，我们测量了来自全球多个地点（包括大西洋、太平洋和地中海沉积物）的大量 SMS 样本的频率相关电特性。结果将在矿物学数据的背景下进行分析，以确定电参数和矿物含量之间的潜在关系，这将构成未来勘探计划的基础。测量之前将进行方法学研究，以确定测量不规则形状样品的电性能的最佳程序。 SMS 样品很有价值，通常不希望破坏它们，因此使用圆柱形塞的标准方法不能应用于所有样品。 数据解释将得到广泛的理论考虑的支持，以便获得对控制矿化岩石电阻抗的物理过程的基本了解。现有理论完全假设矿物是浸染状的，而实验证据表明，相连的矿脉对导电率有巨大影响，不容忽视。我们的理论进步将把现有的电化学模型与最近为未矿化沉积物开发的新方法结合起来。