Lot A4

Barytes

17 New Orebodies Identified For Intensive Investigation

Study Areas: Nasarawa, Benue, Cross River

  • An orientation survey normally consists of a series of preliminary geophysical methods aimed at determining the best methods required to ascertain and outline the mineralization and characteristic signatures associated anomlies
  • The barytes deposits in the Benue Trough appear to be structurally controlled and formed in open spaces or in fault zones frequently with base metal sulphides, here the proper physical and chemical conditions occurred and where metallic minerals can precipitate. 
  • Most of the recorded zones are multi-veined made up of a number of parallel or anastomosing veins generally occurring in an overlapping “en echelon” pattern.  Hence, the control of mineralization is structural. 
  • NMC Vein 17 located in the north-west of Azara town (BlockD2, Middle Benue Trough) was selected for this initial orientation survey.
  • The geophysical surveys were carried out along seven traverses (fig 1) aimed at the exploration of barite using ground magnetic and electromagnetic methods through the following procedures:
    (i) Production of ground magnetic anomaly maps (including their derivatives) of the area of interest.
    (ii) Construction of subsurface conductivity sections and profiles.
    (iii) Mapping of structural architectures that may be favorable to barite mineralization.

Mineralization

  • Linear structures correlating with the known baryte mineralization at Vein 17 have been outlined from the gravity and EM methods.
  • Suspected mineralized veins are characterized by low conductivity responses
  • Barite mineralization is magnetically transparent.
  • The thin nature of some of the ore bodies might make them unsusceptible to geophysical detection
  • Exploration efforts are expected to be focused around the linear structures.

Generally and across the trough, the structural successions that played dominant roles related to  mineralization are as follows:

  • Mineralization is related to the folding episodes that created anticlines and synclines especially in the  Upper and Middle Benue Troughs. The Axes of the anticlinal axes that runs through the axis of the Benue Trough the Lamurde and Keana caused by a Northwest Southeast compression are similar.
  • The later phases of these compressive flexures are accompanied by faulting and fracturing which  were later filled by fluids.
  • The fractures which vary in orientation and possibly favourability for mineralization are also linked to  large scale strike slip faults. In the Upper Benue Trough, these strike slip wrench faults are responsible  for creation of small sub basins. In the Middle Benue however, faulting have been mapped but at a much smaller scales. Vein type deposits are restricted within such fractures accompanied by extensive  silicification.
  • The trends of the baryte veins define three major axes:
    1.  The 090° – 120° (E-W) trends, dominant especially in the highly mineralized Azara Zone.
    2. The 170° – 010° (N-S) trends which appear to be dominant in the Lower Benue Trough, possibly caused by the  NW-SE compression
    3. The 140° – 160°  (NW-SE) trends whose age relationship with possibly succeeding phase of E-W is  not well understood. They occur widespread across the entire region.