Electromagnetic Study in the Minas-Bahia Graphite Province (MBGP)

Description

The Inter-American Development Bank (IDB), in close coordination with the Geological Survey of Brazil (SGB), invites specialized contractors and consulting firms to submit proposals for a helicopter-borne Time Domain Electromagnetic (TDEM) survey across the southeastern portion of the Minas-Bahia Graphite Province (MBGP).

The primary objective of the project is to map subsurface electrical conductivity distributions to advance the geological understanding of the region and support the identification and characterization of graphite-mineralized zones. The survey covers a total of 334.50 linear kilometers across 15 planned flight lines in the SIRGAS2000 coordinate system.

1. Scope of Services & Key Activities
Inception & Executive Planning: Review cartographic/geological data provided by SGB and prepare an Inception Report detailing the execution methodology, mobilization plan, team structure, equipment/software specs, safety protocols, and quality control procedures.

Airborne Field Data Acquisition: Mobilize helicopter-borne TDEM equipment to collect high-resolution data over the designated 334.5 km survey area, maintaining strict adherence to planned flight lines, line spacing, sensor elevation, and noise limits.

Data Processing & Quality Control: Execute advanced data processing including stacking, filtering, removal of atmospheric contribution, transmitter waveform and drift corrections, channel leveling, decay constant calculations, and 2D Conductivity Depth Imaging (CDI) inversions.

Institutional Coordination: Work in direct alignment with SGB's technical team under IDB supervision, observing all regulatory, safety, and data traceability standards.

2. Core Technical Deliverables
Work Plan & Methodology Report: Detailed execution schedule, equipment descriptions, software specifications, and operational procedures for all survey stages.

Technical Report on EM System Effectiveness: Comprehensive assessment verifying system geometry, loop configuration, dipole moment, bandwidth, depth of investigation, noise mitigation (sferics and 50 Hz), and primary/secondary field processing.

Point Location Databases: Validated georeferenced raw and processed data delivered in ASCII (.xyz), Geosoft binary (.gdb), and ASEG-GDF2 formats.

Gridded Data & Map Package:

2D vertical conductivity-depth sections (CDI inversions).

Surface apparent conductivity maps and at least three depth-slice maps.

Secondary field decay time maps and ternary images (early, mid, late channels) for X and Z components.

Stacked profile maps, digital plotting files, and high-resolution PDF map sets at project scale.

Note: Interested companies must review the requirements in the BEO Bidders Portal.