Rock physics modeling for massive sulfide rock samples from seafloor hydrothermal areas
Abstract
Seafloor hydrothermal areas are known as forming fields of massive sulfide minerals and are expected to be metal mineral resources so that several geophysical explorations have been conducted for recent years. However, there are technical problems to make an appropriate interpretation from the explorations' result because of lack of rock physics model which can estimate chemical composition from physical properties of rocks in hydrothermal areas. Therefore, we conducted laboratory investigation for rock samples obtained in seafloor hydrothermal areas, on the several physical properties and chemical composition such as porosity, complex electrical conductivity, grain density, elemental composition, and mineral composition. Subsequently, we constructed a new rock physics model that can explain the measurement results. As a result of the investigation, we observed the high electrical conductivity of more than 10 S/m under the condition of being saturated by seawater and its phase characteristics in our rock samples. They also showed features such as high porosity of more than 20 %, high density of more than 3.0 g/cm3, and concentration of heavy metal elements. By applying our new rock physics model to several physical properties that we measured, we succeeded in reproducing the electrical conductivity characteristics of rock samples. Furthermore, calculating the chargeability of rock samples with our new model, we observed the positive correlation between the heavy metal elements inherent in conductive sulfide minerals and calculated chargeability. These results suggest that our new model can be applied not only to reproduce the electrical conductivity of rock but also to estimate its chemical components from physical properties observed by geophysical exploration. It is thought that it is possible to estimate the content of specific mineral species by analysis based on physical properties with our new model.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.V43F0186O
- Keywords:
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- 0930 Oceanic structures;
- EXPLORATION GEOPHYSICSDE: 1034 Hydrothermal systems;
- GEOCHEMISTRYDE: 3616 Hydrothermal systems;
- MINERALOGY AND PETROLOGYDE: 8424 Hydrothermal systems;
- VOLCANOLOGY