Spectral time domain induced polarization : factors affecting spectral data information content and applicability to geological characterization

• Main Author: Rezvani, Azadeh
• Format: Other/Unknown Material
• Language: English
• Published: Lunds universitet/Geologiska institutionen 2015
• Subjects: Liikavaar; geology; geophysics; resistivity; induced polarization; Aititk mine; AarhusInv; Earth and Environmental Sciences; Liikavaara; Northern Sweden
• Online Access: http://lup.lub.lu.se/student-papers/record/5467175

The geo-electrical survey (resistivity and induced polarization) with different settings, arrangements, time base, spreads and waveforms (50% and 100% duty cycle waveform) was carried out over the Liikavaara depo-sit, near the Aitik mine, in northern Sweden and all the measured data was inverted in two different softwares: Res2Dinv and AarhusInv. Surveys of induced polarization (IP) often contain data of low quality, due to the high sensitivity against noise sources and coupling effects. Measured data with the new method (applying 100% duty cycle waveform), which is much faster than the conventional one (50% duty cycle waveform), present significant improvements in the quality of IP-data. It was also attempted to increase the data quality by separating current and potential cables and restrict the capacitive coupling, which normally occurs between transmitting current and pot-ential receiving wires. Moreover, conceptual models from different measurements were correlated to boreholes close to the survey line, in order to find geological correlation between the models and logging data. There was also a possibility of modeling Tau and C parameters by the newly developed software (AarhusInv) which gave us more detailed information about the mineralization texture (grain size and grain size distribution). They were also compa-red in different measurements and it appears that Tau and C are sensitive to the duration of current injection. However, lack of reference data for interpretation, made the interpretation of these two parameters, difficult and ambiguous. Since the 1900s electrical resistivity and induced polarization methods are one of the common geophysical survey techniques which are applied in subsurface studies and in particular in mineral exploration. In this paper we show how different settings, arrays, waveforms, cable spreads and time base can affect the data quality/ the final inversion models for resistivity and IP . The results from this study show that the acquired IP data are of higher quality ...