A case of ore deposition associated with paleogeothermal activity: The polymetallic ore veins of Aïn Barbar (NE Constantinois,Algeria)

The Aïn Barbar area was at Langhian times the site of a terrestrleial high energy geothermal field related to acid Langhian magmatic activity. A granite body probably occurs at depth, as evidenced by microgranite and rhyolite dikes. The reservoir is made up of Upper Cretaceous Massylian flyschs, overlain by an impermeable cover of Oligo-Miocene Numidian flysch. Due to erosional unroofing, its thickness, initially on the order of one kilometer, was probably halved towards the termination of activity of the liquid-dominated geothermal field.Geothermal activity, which lasted about 1 Ma, developed in two stages: