Resistivity Methods(Case Study: Chromite Vein Subsurface Analysis Using Resistivity Methods)

Gunawan

Geophysicist

Introduction

Main purpose of case study using resistivity method was to:

“identification and estimation of chromite vein in subsurface based on resistivity values”

Resistivity Method

Resistivity method is one of the oldest geophysical survey techniques. (M.H. Lokes, 2011)

Main Purpose:

“determination the subsurface resistivity distribution by making measurements on the ground surface”

Ground resistivity is related to various geological parameters such as mineral and fluid content, porosity and degree of water saturation in the rock.

This method have been used for many decades in many exploration such as hydrogeological, mining, geotechnical, environmental, and even hydrocarbon. (Loke el al, 2011, & 2013a)

Basic Theory

Resistivity measurements are still made by injecting current into the ground through the two current electrodes (C1 and C2 in figure above), and measuring the resulting voltage difference at two potential electrodes (P1 and P2 in figure above).

From the current and potential values, an apparent resistivity value is calculated like below:

Kind of Resistivity Configuration

(Loke, 2011)

Result

Interpretation

Boulder (Chromite)

Bedrock (Peridotite)

Boulder (Chromite) : > 800 ΩmBedrock (Peridotite) : < 800 Ωm

Sea Water : 0 – 5.0 ΩmFresh Water : 5.0 – 10.0 Ωm

Conclusion

Based on the resistivity section, the chromite vein can be found about ± 10 metres from measuring surface. In this case, resistivity

interval values of them above 800 Ωm.

Thank You