Geological Mapping

Eighteen (18) geological Quarter Degree Sheets covering an approximate area of 54,000 km2 have been selected for geological mapping and maps will be published at a scale of 1:100,000. Out of these, there are 12 unmapped QDS and six (6) QDS will be up-dated from a scale of 1:125,000 to 1:100,000. In addition two blocks covering a total of 314,928 sq km will be compiled followed by field checks and maps published at scale of 1:500,000
Upgrading of Six geological QDSs (scale 1:100,000)
Acquisition of new data and information through field geological mapping, geophysical and geochemical surveys as well as updating existing geological maps. Six (6) QDSs covering an area of about 18,000 km2 have been selected for updating. They include QDSs 146, 147, 148 and 165 (Handeni and Kilindi) in Tanga region; QDS 228 and 229 (Lupa Goldfield in Mbeya region) (see figure 2). The scope of work to be undertaken include compilation of available data and information; field checks and map editing, data processing and interpretation; map preparation, publication and reporting.
Geological mapping of 12 QDSs (scale 1:100,000)
A total of 12 QDSs covering about 36,000 km2, will be mapped and compiled at a scale of 1:100,000. These include QDS 82, 83, 101, 102 (Singida-Iramba Sekenke); QDS 185 (Coastal region); QDS 178, 79 (Dodoma-Mafurungu); QDS 272, 273, 230 (Mbeya region); and QDS 263 (Ruvuma region). The work shall involve compilation of available data and information; field work; petrological and petrophysical studies; laboratory analysis and map preparation at a scale of 1:100,000.
Compilation of regional geological, geophysical and mineral potential block maps (scale 1:500,000)
This will entail compilation and synthesis of existing data and information; conducting geological and geophysical field checks in selected areas; laboratory analysis; data compilation and production of geophysical maps from the old airborne geophysical data archived at GST. Samples for geochronology age determination of rocks will be collected for the purpose of age correlation. Two blocks covering 324 km2 have been selected for compilation of regional geological, geophysical and mineral potential maps at the scale of 1:500,000. They include the Singida-Handeni corridor (Block A with 54 QDS sheets) and Mbeya-Songea corridor (Block B with 54 QDS sheets) as shown in figure 2. Twenty eight (28) QDSs are within the areas selected for the airborne geophysical survey in the Singida – Handeni corridor.

Fig.2:Proposed Areas for Undertaking Geological Mapping

Expected Products From Geological And Geochemical Mapping:

  • Soft and hard copy of the interpreted remote sensing data integrated with topographical data for scales 1:100,000 and 1:500,000 of the project area. The digital copies shall be compatible with MIS;
  • Digital data of selected thematic geophysical maps and images and interpretations as compatible Arc Info/Arc View coverage including ternary images of radiometric data, filtered grey-scale and other derivative images of total magnetic field, geophysical modeling of selected geophysical anomalies and cross-sections;
  • Petrophysical and age dating database of major rock types found in the survey area;
  • A set of digital and hard copies of provisional geological, geophysical (magnetic and radiometric) and structural maps (two copies of each sheet) at scale 1:100,000 and 1:500,000 of the project area. The digital copies shall be compatible with MIS, coded and presented as separate digital layers;
  • A set of digital and hard copies of geochemical maps at scale 1:100,000;
  • Published geochemical report;
  • Provisional geological, geophysical, geochemical exploration programmes for short-, medium- and long-term.

Geoscientific Data Management

The following activities shall be implemented under the Project:

  • modernizing the existing geological and mineral information system, including system design, training, equipment and software, including GIS update;
  • compiling, digitizing and storing into GIS all available geological and mineral information generated prior and during the proposed project;
  • Upgrading the capacity of the GST to process and disseminate geo-scientific data for a multi-sector client demand; and establish Geological Mineral Information System (GMIS) based on the GIS technology and relational databases.

Expected Products at the end of the Project:

  • A fully equipped, operational remote sensing laboratory , GIS and internet/ Intranet network at GST
  • A well-functioning GMIS with efficient data sets inter-linkages and all the necessary security measures; a geoscientific resource centre linking all the information systems within GST as well as possible links to other geoscientific institutions and MEM.
  • digital data dissemination policy manuals;
  • Knowledgeable and skilled personnel that can manage and maintain the new systems;
  • A comprehensive user manual of the new geological and mineral information system and internet/intranet as well as up to date standards for map production;
  • Computer based cataloguing system for the library, archive, museum displays and rock store;
  • Updated geological and metallogenic maps of Tanzania ; an authoritative book on the geology, stratigraphy and mineral resources potential of Tanzania;
  • Published 60 digital geological QDS maps ;
  • Mineral resources potential of the country and GST services promotional materials; and
  • A modern geological museum

Technical specifications

Aerogeophysical survey description

The survey includes three survey methods:

  • Magnetic total field measurements
  • Dual-frequency electromagnetic measurements
  • Radiometric gamma-ray measurements

Survey equipment

QDS map sheets 30-31, 44-45, 62, 78 (Twin Otter aircraft)

Two Caesium magnetometers installed at the wing tips

  • Distance 21.36 meters
  • Registration frequency 10 Hz

Dual-frequency electromagnetic unit

  • Coil distance 21.36 meters
  • Lower frequency 3 125 Hz, higher frequency 14 368 Hz
  • Registration frequency 4 Hz

Gamma-ray spectrometers

  • Two sets of NaI crystal units (four downward and one upward looking crystal)
  • Total volume 42 liters
  • 256 channels, energy range 0.01 – 3.00 MeV
  • Registration frequency 1 Hz

QDS map sheets 4-5, 12-13, 153-155 (Cessna Caravan aircraft)

One Caesium magnetometer installed at a back boom

Registration frequency 10 Hz

Dual-frequency electromagnetic unit

  • Coil distance 21.36 meters
  • Lower frequency 3 125 Hz, higher frequency 14 368 Hz
  • Registration frequency 4 Hz

Gamma-ray spectrometers

  • Two sets of NaI crystal units (four downward and one upward looking crystal)
  • Total volume 42 liters
  • 256 channels, energy range 0.01 – 3.00 MeV
  • Registration frequency 1 Hz

Data format description
XYZ Files

There is one Geosoft XYZ file corresponding to each survey method (magnetic, radiometric and electromagnetic measurements) and each QDS map sheet. In addition to the measured component files there are also separate files for calculated apparent resistivities, digital terrain models and total gamma-ray dose data.

As the map sheets 4-5, 12-13 and 153-155 were surveyed using one magnetometer whereas on the map sheets 30-31, 44-45, 62 and 78, two magnetometers were used, there are two different naming conventions and file structures for magnetic data files.

The files are named as follows (# means the varying QDS map sheet number):
AP#.XYZ apparent resistivity data (all map sheets)
DTM#.XYZ digital terrain model (all map sheets)
EM#.XYZ electromagnetic data (all map sheets)
MB#.XYZ back boom magnetometer data (map sheets 4-5, 12-13, 153-155)
ML#.XYZ left wingtip magnetometer data (map sheets 30-31, 44-45, 62, 78)
MR#.XYZ right wingtip magnetometer data (map sheets 30-31, 44-45, 62, 78)
RA#.XYZ radiometric data (all map sheets)
TO#.XYZ gamma-ray dose data (all map sheets)

XYZ File Columns

Each row in these ASCII files corresponds to one measurement point. One column of the row corresponds to one measurement parameter.

The data includes the following columns:

Electromagnetic data files
X, Y ARC1960 coordinate pair X, Y (easting, northing respectively) (meters)
DAY Day number from the beginning of the year
TIME Measurement time stamp (hhmmss)
DIR Flight direction (degrees, clockwise from north)
RALT Radar altitude (meters)
LFR In-phase component of the lower frequency (3 005 / 3 125 Hz) (ppm)
LFI Quadrature component of the lower frequency (3 005 / 3 125 Hz) (ppm)
HFR In-phase component of the higher frequency (14 368 Hz) (ppm)
HFI Quadrature component of the higher frequency (14 368 Hz) (ppm)

Magnetic data files: map sheets 4-5, 12-13, 153-155
X, Y ARC1960 coordinate pair X, Y (easting, northing respectively) (meters)
DAY Day number from the beginning of the year
TIME Measurement time stamp (hhmmss)
DIR Flight direction (degrees, clockwise from north)
RALT Radar altitude (meters)
MB65 Total magnetic field of the back boom magnetometer at IGRF65 level (nT)

Magnetic data files: map sheets 30-31, 44-45, 62, 78
X, Y ARC1960 coordinate pair X, Y (easting, northing respectively) (meters)
DAY Day number from the beginning of the year
TIME Measurement time stamp (hhmmss)
DIR Flight direction (degrees, clockwise from north)
RALT Radar altitude (meters)
ML65 Total magnetic field of the left wingtip magnetometer at IGRF65 level (nT)
MR65 Total magnetic field of the right wingtip magnetometer at IGRF65 level (nT)

Radiometric data files
X, Y ARC1960 coordinate pair X, Y (easting, northing respectively) (meters)
DAY Day number from the beginning of the year
TIME Measurement time stamp (hhmmss)
DIR Flight direction (degrees, clockwise from north)
RALT Radar altitude (meters)
BALT Barometric altitude (m)
TOUT Temperature outside the aircraft (°C)
D_KAL Potassium concentration (% K)
D_URA Uranium concentration (ppm equivalent uranium eU)
D_THO Thorium concentration (ppm equivalent thorium eTh)

Apparent resistivity data files
X, Y ARC1960 coordinate pair X, Y (easting, northing respectively) (meters)
DAY Day number from the beginning of the year
TIME Measurement time stamp (hhmmss)
DIR Flight direction (degrees, clockwise from north)
RALT Radar altitude (meters)
LFA Calculated lower frequency (3 005 / 3 125 Hz) apparent resistivity (m)
LFS Calculated apparent depth corresponding to LFA (m)
HFA Calculated higher frequency (14 368 Hz) apparent resistivity (m)
HFS Calculated apparent depth corresponding to HFA (m)

Digital terrain model files
X, Y ARC1960 coordinate pair X, Y (easting, northing respectively) (meters)
DAY Day number from the beginning of the year
TIME Measurement time stamp (hhmmss)
DIR Flight direction (degrees, clockwise from north)
RALT Radar altitude (meters)
DTM Digital terrain model above the WGS84 ellipsoid (m)

Gamma-ray dose data
X, Y ARC1960 coordinate pair X, Y (easting, northing respectively) (meters)
DAY Day number from the beginning of the year
TIME Measurement time stamp (hhmmss)
DIR Flight direction (degrees, clockwise from north)
RALT Radar altitude (meters)
BALT Barometric altitude (m)
08:38:50TOUT Temperature outside the aircraft (°C)
D_TOT Dose rate (nGy/h

Grids
The grids are interpolated with the minimum curvature algorithm of Geosoft Oasis Montaj for all the parameters except apparent resistivity in which Akima spline method is used. Grid cell size is 50 meters for all the grids.
There is a corresponding grid for all the geophysical parameters of each map sheet. In addition there are also grids for digital terrain models (base level WGS84 ellipsoid). The units of the grid values correspond to those in the XYZ files.

Grids are named as follows (# means the varying QDS map sheet number):
DTM#.GRD Digital terrain model
HFA#.GRD Higher frequency (14 368 Hz) apparent resistivity
HFI#.GRD Higher frequency (14 368 Hz) EM quadrature component
HFR#.GRD Higher frequency (14 368 Hz) EM in-phase component
KAL#.GRD Potassium
LFA#.GRD Lower frequency (3 005 / 3 125 Hz) apparent resistivity
LFI#.GRD Lower frequency (3 005 / 3 125 Hz) EM quadrature component
LFR#.GRD Lower frequency (3 005 / 3 125 Hz) EM in-phase component
MAG#.GRD Magnetic total field
THO#.GRD Thorium
TOT#.GRD Total radiation dose rate
URA#.GRD Uranium

Tanzania Census 2022