By present time, Aerogeophysica gained wide experience of DIP survey in different regions of Russia and CIS under different exploration projects:

preparation of the geophysical base for geological mapping on scales 1:200000 – 1:25000;
conductive and non- conducting targets exploration;
primary diamond deposits exploration;
mapping of loose sediments;
paleochannel, landslide and karst zones mapping;
pre-quaternary sediments mapping;
fracturing and watering zones mapping;
tectonic mapping;
permafrost, watering and talik zones mapping;
Successfully  fulfilling the tasks connecting with mapping of upper parts of section, DIP-4A survey in the most cases can replace traditional 2-3 frequency profiling, with scale up to 1:10000, by offering an advantages of work performance and project cost over ground EM measurements. 

DIP-4A can be integrated with any employed to-day airborne geophysical equipment.

EM system EM-4H

This system is destined for ore, non-ferrous and precious metals exploration, ground water exploration.

The core of system EM-4H is frequency EM system (modification of DIP-4A), combining simplicity and informative of the measurements with their high resolution and deep penetration. The transmitter loop is installed onto aircraft (fixed wind or helicopter), and the receiver is mounted in towed bird.

More than sixtyfold difference between higher and low frequencies ensure the depth of reliable measurements and possibility to identify blind targets within different geological sections with high or low conductivity.

The integral module of the system is an airborne magnetometer with mounted in the same as EM receiver towed bird.

For the positioning the combines system GPS Navstar- Glonass is used.

Optionally, depending on the project requirements and geological situation, the EM system can be integrated with airborne spectrometer..

EM-4H on helicopter MI-8 MTV

Technical description

ЕМ system:

The transmitter consists of the generating exiting dipole multi-turn loop, mounted on the fuselage of the aircraft, and the directly coupled with on board power supply generator. The bird with three-axis receiverand magnetometer sensor is towed on 70 m length tow cable.

The output is in-phase and quadrature field components for each of three sensor axis on each of work frequencies.

Features

- Work frequencies (sin impulse): 130, 520, 2080, 8320 Hz.

- Dipole moments: 20000, 10000, 4000, 2000 A∙м².

- Loop square: 42 m² (aircraft AN-2, AN-3), 60 m² (helicopterдля MI-8)

- Required power supply: 540 W (20 A, 27 V).

- Tow-cable: Kevlar shielded twisted-pair cable 70 m.

- Interface: RS232, Ethernet (TCP/IP).

Magnetometer:

Type: cesium vapor

- Resolution 0.001 nT;

- Measurement rate: 20 Hz;

- Tolerance 20000 nТ/m;

- Measurement range: 17000 - 100000 nT;

Sensor Cs-3 (or analog) is mounted in towed bird.

Spectrpmeter: 

- Digital 512 channel spectrometer with NaI(Tl) detectors with total volume up to 48 l.

- Resolution on level 0.662 MeV (Cs-137) better 11%.

- Measurement range 0.38 – 5.0 MeV.

- Registration rate  - 1 sec.

- Automatic stabilization in Th window.

DAS software:

Includes flight control, recording of EM, magnetics, spectrometr, and navigation data. The positioning accuracy allows to carry out the survey on scale 1:5000 and more detailed survey. For registration of diurnal variations and differential GPS correction the ground base stations are used.

 
Below shown the results of EM-4H survey on scale 1:25000. (Kureyka area).

Fig.1 Effective resistance and anomalous magnetic field maps.

Geological map (left). Local magnetic anomalous and conductivity map (right). The perspective areas countered by red. 

Combined airborne geophysical survey in Polar Ural. The survey scale 1:10000.

Maps: effective resistance (above); K concentration and Δ T lower.

 After data processing and interpretation the existing geological map has been essentially detailed. It is illustrated in figure below.

Geological map created in 90’s (left). Detailed map created with recently obtained data (right). As a result was delivered predictive scheme for Fe, Cu,

 EM-4H survey allows to map perspective sites within project area, and, in case of appropriate geo-electrical conditions, to indicate the project target.  

The standard specifications for EM-4H survey are 25 and 50 m flight space.