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Fault detection in 3D by sequential Gaussian simulation of Rock Quality Designation (RQD)

Case study: Gazestan phosphate ore deposit, Central Iran


Gazestan phosphate ore deposit (Central Iran) is an apatite deposit which is instrumental in selecting the method of excavation. The position of fault systems and the condition of rock quality also play a role in the method used for mineral resources and ore reserves estimation. Conversely, the Rock Quality Designation (RQD) is a parameter that provides a quantitative judgment of rock mass quality obtained from drill cores. This factor can be applied to detect the fractured zones which occur due to fault systems. Additionally, the faulted areas can be determined by surface geological map and a few by core drilling. Some of the faulted areas are not distinguishable in the surface and are covered by soils, especially within 3D modeling and visualization. In this study, an attempt has been made to establish a relationship between the RQD percentages which were geostatistically simulated and faulted areas through the region. In comparison, the results showed that low RQD domains (RQD <20 %) can be interpreted as fault zones; high RQD domains (RQD >50 %) correspond to less fractured areas, and the contact between high and low RQD domain is gradual. Therefore, this categorization of RQD domains can be incorporated to detect the faulted zones in 3D models for mine design. Based on the categorization, the uncertainty within the area was calculated to introduce two new core drilling points for the completion of this phase of exploratory grid from the fault structural viewpoint, in order to have a proper model of ore reserve to estimate. It was concluded that this procedure can be utilized for conceptual comprehension of fault trends in 3D modeling for the method selection of excavation and complete the estimation procedure phase.

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The authors acknowledge the financial support of the University of Tehran for this research under grant number 28350/1/04.

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Correspondence to Nasser Madani Esfahani.

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Madani Esfahani, N., Asghari, O. Fault detection in 3D by sequential Gaussian simulation of Rock Quality Designation (RQD). Arab J Geosci 6, 3737–3747 (2013).

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  • RQD
  • Sequential Gaussian simulation
  • Gazestan ore deposit. 3D fault detection