the use of low-frequency GPR Loza, for prospecting and exploration of mineral resources. Capabilities. Methodology. Examples. Comparison with other methods.

1. PhD in Geology Kadurin Sergii
GPR technique applied to mineral exploration

2. Kadurin Sergii
PhD in Geology
Assotiate Proffesor of
Odessa I.I. Mechnikov National
University (Ukraine)
KadurinS@gmail.com
+38-0687524133
Faculty of Geology and
Geography
ONU

3. Why GPR?
• GPR is easy to use;
• You can get information about the deep structure quickly;
• The prices for GPR equipment and services are lower that for the
another geoelectrical methods.

4. What is the GPR?
• GPR – ground-penetrating radar.
• GPR works with electromagnetical wave reflections.

5. The depth of study:
Limited by next parameters:
• Electrical permittivity and conductivity of the ground;
• Transmitted frequency;
• Radiated power.

6. Electrical properties
• Conductivity is the ability of a material to support an electrical
current (material property that describes the movement of electrons
or ions) due to an applied electrical field. (units – Siemens/metere
(S/m))
• As conductivity increases, the penetration depth decreases

7. General divisions of materials by electrical
conductivity
 Low conductivity – excellent radar conditions (<10-7 S/m)
 Air;
 Dry granite, dry limestone;
 Concrete
 Medium conductivity – medium radar conditions (10-7 – 10-2 S/m)
 Freshwater, freshwater ice, snow;
 Sand, silt, dry clay, basalt, seawater ice.
 High conductivity – poor radar conditions (>10-2 S/m)
 Wet clay, wet shale,
 Seawater.

8. Transmitted frequency
• Usually GPR uses high-frequency electro-magnetic waves;
• Higher frequencies do not penetrate as far as lower frequencies, but give
better resolution.
Antenna frequency Maximum penetration depth Examples of potential use
900 MHz 1 m Pipe and void detection or assessing of concrete thickness
400 MHz 4 m Utility survey, storage tank detection, assessing structural
integrity
300 MHz 6 m Utility survey, geology and archeology.
25 MHz 190 – 205 m Exploration.

9. Power of transmitter
• The GPR transmitter produces the short duration high-power pulses of
energy that are radiated into ground by the antenna.
• There are two types of pulses can be used in GPR: oscillating and non-
oscillating.
oscillatingnon-oscillating

10. Received data

11. Data analysis
Depth can be calculated:
c – propagation velocity in free space
(3*108 m/s)
Vm – propagation velocity through the
material
εr – relative permittivity

12. Dielectric constant
• Dielectric permittivity is the property that describes the ability of
material to store electric energy by separating opposite polarity
charges in space (units – Farad/meter (F/m))
• Relative dielectric permittivity (dielectric constant) is the ratio of the
permittivity of a material to that of free space – 8.854*10-12 F/m (No
unit)

13. Relative dielectric permittivity
• The range of relative dielectric permittivity is 1 – 81;
• Dielectric permittivity differences at boundaries cause reflections in
the radar data, the strength of reflections is controlled by contrast in
the dielectric permittivity;
• The value of relative dielectric permittivity is primarily controlled by
water content.

14. Approximate electrical properties of various materials

15. Reflections
• When the waves hits the buried object or a boundary with different
dielectric constants, the receiving antenna records variations in the
reflected return signal.

16. Simplified diagram of GPR construction and profiles (adopted
from Butler an al (1991) and Daniel at al (1988)

17. Some questions:
• How it works if we need to find subvertical geological bodies like
veins, dykes or cracks and faults?
• How to detect a body with smooth geological boundary?
• Is that possible to detect mineralization in the rocks?

18. GPR “LOZA”
LOZA series is commercial GPR produced by a Russian company VNIISMI
and is widely used in industrial geology, archeology and civil engineering.

19. GPR “LOZA”
LOZA GPR series has been designed specially for high-conductivity soils (wet clay, loam). To
increase the devise effective potential we raise the transmitter peak power by a factor of 10000
and replace stroboscopic transformation with direct registration. Note that despite the peak
power enhancement the average power decreases by a factor 10 due to reduced repetition rate.
• We use high power transmitter on basis of hydrogen spark-gap;
• Transmitter pulses are in asynchronous mode. Synchronization realize in the receiver as a waiting
mode by air waves;
• We replace stroboscopic transformation by direct registration in the working frequency range;
• Transmitter and receiver have no electrical coupling;
• We use only resistive loaded dipoles as antenna. That antennas have the low level of “ringing”.

20. LOZA-N GPR low frequency, deep penetration

21. The signal energy dissipation in geological section
h
σε1
ε2
1
2
3
1. Signal attenuation from transmitter to geological boundary on depth h.
𝐴1 = 𝐴0 𝑒−2𝑝ℎ
Where p is the attenuation coefficient p =
𝜔
с
𝜀
2
( 1 + tan2 𝛿 − 1)
2. Reflection coefficient on the geological boundary
R =
𝜀1
− 𝜀2
𝜀1
+ 𝜀2
3. Signal attenuation from geological boundary on depth h to receiver.
𝐴3 = 𝐴2 𝑒−2𝑝ℎ
A2 = RA1
tan 𝛿 =
𝜀′
𝜀′′
=
𝜎
2𝜋𝑓𝜀0 𝜀
𝜔 = 2𝜋𝑓

22. The signal energy dissipation of Loza-N GPR in limestone – granite geological section
h
σ=0.0005
ε1=9
ε2=4
1
2
3
limestone
granite
0
50
100
150
200
250
1E-08 0.0000001 0.000001 0.00001 0.0001 0.001 0.01 0.1 1 10
Depthh
Returned energy A3
A0 = 21kV A3 - ?
Receiver sensitivity

23. LOZA-N applications

24. Loza-N in Peru (Condor area)
• Distrito de Pachaconas, provincia de Antabamba, Apurímac.
• Veins with mineralization are the main target.

25. Main objectives of the work:
• Identification of fractures and cracks;
• Identification of mineralized veins;
• Identification of deep structure.
Section of
Maiskoe Gold deposit
Russia.

26. Work process
• The work was done 25 /07 /2016;
• 3 profiles have been done with total length 576 m;

27. Loza-N in Peru
• There are 3 profiles have been made
1
2
3
PROFILE 1- 176 m
PROFILE 2- 192 m
PROFILE 3- 208 m
N

28. Profile 1 (50 m depth)

29. Profile 1 (200 m depth)

30. Profile 2 (50 m depth)

31. Profile 2 (200 m depth)

32. Profile 3 (50 m depth)

33. Profile 3 (200 m depth)

34. How to detect intrusive body by GPR?
Another project in Peru – Ica area.
Numerous andesite and quartz monzonite dykes and veins are crossed
the area.
Granodiorite intrusion is the biggest magmatic body in that area
Zone of mineralization can be detected on the border between
granodiorites and country rocks.

35. Geological map of
studied area.

36. Profiles on the area.

37. Profile 2.2
• Andesite dyke can be detected.
• Deeping of dyke and underground
structure can be detected.

38. Profile 2.0
• Dykes and veins can be
detected.
• Intrusive body with weathered
top part have been detected.

39. GPR profiles interpretation in 3D

40. How to detect ore body?
• The low frequency GPR allows to reveal the structural features (bedding,
faults, intrusive bodies and other structural heterogeneity), as well as the
identification of polarizable and low conductivity areas.
• Parts of sections where the rocks can be polarized we can interpret as
rocks with ferromagnetic properties, and the areas of low conductivity,
we call “dielectric zones”.

41. Example of polarized ore body
Potential ore‐bodyFaults
Dielectric
Contact –
Weathered /
non‐ weathered
zone

42. Project “Cobre”

43. Project “Cobre”

44. Project “Manuelito”

45. How we can compare GPR with IP?
There are three veins can be
detected on GPR profile (top).
On IP profile only some round
anomalies can be identified.
Because of GPR profiling
we can identify the real
shape of underground
geological body.

46. GPR and IP comparison.
Please note:
steep topography has influence
on our path through the area –
so IP lines are not exactly the same
as GPR profiles because we had to
use paths to walk on.

47. Hierro project
with Hematite
mineralization

48. Hierro project.
Ore bodies with Hematite – Magnetite mineralization

49. Conclusions about GPR LOZA-N using in
mining projects:
• The low frequency GPR like Loza-N can give a good result for sub-vertical
veins and fracture zone detection;
• Powerful transmitter (20 MV) allows to make geophysical profile to the
200 m depth and to see the deep structure and position of veins on the
big depth.
• Ore zones can be detected on GPR profile and distinguished from
surrounding rocks.

50. GRACIAS
THANKS