Development of the induced polarization theory with application to exploration of strategic raw materials

近二十年来，光谱诱导极化（SIP）方法因其可以远程研究土工材料的界面特性而备受关注。因此，SIP在水文地质、污染物水文、岩土工程和矿产勘探等领域的应用越来越广泛。然而，迄今为止，在感应极化现象的物理和化学理论中有许多观点是矛盾的和未充分研究的。首先，不同机制（界面机制、p-和n-载流子扩散、电磁感应和麦克斯韦-瓦格纳效应）在金属粒子极化（MP）中的作用尚不清楚。其次，每种岩石极化机制模型只描述一种机制（电双层极化的斯特恩层、膜极化或麦克斯韦-瓦格纳极化）。没有一个模型包括所有的机制。该项目的目标是填补上述空白。我们期望：-建立统一的金属粒子IP模型；-改进岩石极化的机理模型。为了验证这些模型，我们将对一些具有重要经济意义的矿床典型的岩浆岩和热液蚀变岩的天然样品进行一系列广泛的实验室实验。然而，天然样品（高度非均质）在矿物组成和孔隙结构方面总是分选不佳。因此，我们将使用控制良好的合成样品来阐明新模型的某些方面。因此，我们将编制一个新的广泛的SIP数据数据库，供科学界重用。此外，为了测试这些模型，我们将利用COMSOL Multiphysics软件包对Nernst-Plank - Poisson-Boltzmann微分方程的解进行数值再现，以负责IP的现象。此外，我们还讨论了SIP数据处理的两个方法学方面。首先，可以假设并非所有的极化响应都具有德拜特性。然而，实验数据经常用德拜分解（DD）程序拟合。我们建议将DD方法扩展到非debye松弛情况。然后，通常使用时域（TD）技术进行现场调查，而岩石物理研究则使用频域（FD）技术进行。因此，必须对TD和FD数据进行比较。然而，对于真实的实验室，特别是现场数据，TD - FD转换并不简单。为此，我们计划改进TD - FD转换技术。最后，将理论和方法成果应用于找矿工作。提出研制TD IP录井样机，在矿床内进行测试，并对IP录井的信息输出进行评价。如果这项任务成功，我们相信将获得一种有前途的矿石勘探技术，商业和国有企业将需要这种技术。

Within last two decades, Spectral Induced Polarization (SIP) method attracts researchers because it allows to remotely investigate interface properties of geo-materials. As a result, SIP is increasingly used in hydrogeology, contaminant hydrology, geotechnics and mineral exploration. However, to date many points in the physical and chemical theory of Induced Polarization (IP) phenomena are contradictory and understudied. First, the role of different mechanisms (interfacial mechanisms, diffusion of p- and n-charge carriers, electromagnetic induction, and Maxwell-Wagner effect) in polarization of metallic particles (MP) is unclear. Second, each mechanistic model of rock polarization describes only one mechanism (the Stern layer of the Electrical Double Layer polarization, the membrane polarization, or the Maxwell-Wagner polarization). No model includes all of the mechanisms. The objectives of the project are to fill the above-mentioned gaps. We expect: - to develop an unified model of IP of metallic particles;- to improve the mechanistic models of rock polarization.In order to validate these models, we will carry out an extensive series of laboratory experiments with natural samples of magmatic and hydrothermally altered rocks typical of some economically important ore deposits. However, natural samples (being highly heterogeneous) are always poorly sorted in terms of mineral composition and pore structure. Therefore, we will use well-controlled synthetic samples to clarify some aspect of the new models. As a result, we will compile a new extensive database of SIP data available for the scientific community for reuse.Moreover, to test the models we will reproduce numerically the phenomena responsible for IP based on solution of the Nernst-Plank - Poisson-Boltzmann differential equations with the COMSOL Multiphysics package. In addition, we address two methodological aspects of SIP data processing. First, it can be assumed that not all polarization responses indicate a Debye character. However, experimental data are frequently fitted with a Debye Decomposition (DD) procedure. We propose to extend the DD approach for non-Debye relaxation case. Then, field surveys are typically performed with the Time Domain (TD) technique, whereas petrophysical researches are carried out with the Frequency Domain (FD) technique. So, TD and FD data must be compared. However, for real lab, and, especially, field data the TD – FD transformation is not straightforward. For this reason, we plan to improve the TD - FD transformation technique. Finally, the theoretical and methodological results will be applied to ore exploration. We propose to develop a prototype of TD IP logging instrument, to test it within ore deposits, and to assess the information output of IP logging. If this task is successful, we believe to obtain a promising technology for ore exploration, which will be demanded by commercial and state enterprises.