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I. What Parameters the High-power IP System Gain?
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• Tx sycle: as the figure shows, it is the time of “+supply, power off, -supply, power off”.
• M1 width: the width of the first sub-sample(M1), the selections include 20ms, 40ms, 80ms, 160ms.
Four groups polarization sampling width:
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• Power off delay: the time from power off to the start of M1, which is used to reduce the interference of the electromagnetic coupling to the measurement.
• Decay curve: after cutting off the stable current to the ground, the difference of potential electrode decreased rapidly at beginning, then slow the decreasing speed, and decay to zero after quite a long time, the slowly decaying secondary field curve is decay curve.
• Apparent resistivity (R0/ρs): a parameter that can well reflect electrical state and illustrate geological structure. It also plays an important role in groundwater exploration.
 K is the array constant,
 Unit is meter, AM, AN, BM, BN are the distance between A,B and M,N.
• Self-potential (SP): Small currents are naturally produced beneath the Earth‘s surface ; larger ground potentials are produced by conductive mineralised ore bodies that are partially immersed below the water table.
• Induced polarization (IP): Induced polarization is observed when a steady current through two electrodes in the Earth is shut off: the voltage does not return to zero instantaneously, but rather decays slowly, indicating that charge has been stored in the rocks , reflected by M1~M7. often used in exploration for minerals and can sometimes distinguish different types of mineralization.
• Apparent plarizability (M1~M7): We often choose M1.
• Half decay time (TH): half life can exactly plots groundwater structure; for earth that containing water, half life is relatively higher and apparent resistivity is relatively lower.
• Deviation (r): in inverse proportion to water amount.
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| II. What Information They Tell Us? |
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• High induced polarization/ chargeability is usually caused by the presence of metallic or conductive minerals.
• Low resistivity in rocks having a low chargeability is more likely due to conductive moist clays instead of metallic minerals.
• Distinctly low resistivity may correspond to zones containing abundant metallic sulfides.
• Distinctly high resistivity (low chargeability) may correspond to areas containing abundant quartz or silicification.
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| III. How System Gains the Parameters? |
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• A controlled electric current (IP) is passed through the soil between four electrodes (A, B and M, N).
• Current/Receiving electrodes A, B carry the current (I); Potential/Receiving electrodes M, N measure voltage (V)
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| IV. How to Detect Deeper? |
 • Spacing between the electrode pairs needs to increases.
• Stronger current (transmitting power and voltage) is need.
• Theoretical derivations and practical tests have shown that the approximate detection depth can vary from1/3 to 1/6 of [AB] for the arrays of Schlumberger and Wenner types.
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