Aïn Barbar, Edough-Cap de Fer Massif, Constantine District, Constantine Province, Algeria

Located in the NE of the Constantine District.

Langhian (16-15 My) terrestrial palaeogeothermal field (stratified aquifer) with polymetallic Fe/Zn/Cu/Pb-veins.
Host rocks : Nappe of Numidian clay-quartz oligo-miocene flysch and Cretaceous clay-carbonate flysch (deeply altered by the high energy geothermal system).
The flyschs are crosscut by microgranite and rhyolite dykes ; propylitic, sericitic and potassic alteration.
The silification is important.
The vein mineralization is located in shear zones (Playfair and Abaïd veins), it is quite complex:
- Early stage
Chlorite-epidote
- Main stage
Sphalerite, pyrrhotite H
Quartz, sphalerite
Quartz (silicification), chlorite, phengite
Illite, chalcopyrite, pyrrhotite M
Pyrite, calcite
- Late stage
Vein breccia fillings, comb quartz with microcrystalline quartz and chalcedony.
Quartz, adularia
Calcite, chlorite
Siderite
Phengitic illite
Fluorite
Various sulfides

Evolution : 130-80 bars, 320-180°C.

Ref::
Ch. Marignac (1988): Bull. Minéral., 111, 359-381.