LEAD-ZINC MINERALIZATION IN THE CRETACEOUS SEDIMENTS OF BENUE TROUGH OF NIGERIA

The Nigeria lead-zinc (Pb-Zn) deposits occur in the Cretaceous sediments of the Benue Trough. The tectonic activities which led to the formation of the Benue Trough are believed to be responsible for the lead-zinc occurrence.

The Benue Trough is believed to have originated as a failed arm of an aulacogen, and at the time of the separation of the South American and African plates.

The Nigeria Benue Trough is subdivided into Upper-Benue Trough, Middle-Benue Trough, and Lower-Benue Trough. These segments have their various characteristics, lithological associations and stratigraphic sequences which plays host to the deposits.

The sediments of the Asu-River Group which unconformably overlies the Basement Complex in Lower and Middle Benue plays host to the deposits, while the medium-grained arkosic sandstones intercalated by characteristic cross-beddings of the Bima (Upper Albian) and the Yolde formation does same in the Upper Benue Trough.

Barites (BaSO4), Copper (Cu), Silver (Ag), Chalcopyrites (CuFe2), marcasites (FeS2) are some of the minerals that occur are in association with lead-zinc. The mineralization is restricted to NE-SW trending belt of slightly deformed volcanic and sedimentary Cretaceous sequences.