The Hajjar deposit of Guemassa (SW Meseta, Morocco): a metamorphosed syn-sedimentary massive sulphide ore body of the Iberian type of volcano-sedimentary massive sulphide deposits

摘要

The Hajjar deposit is a concordant massive sulphide lens of presumably Visean age located at the top of a volcanic-dominated formation (tuffites, hyaloclastites, pyroclastites, lava domes of rhyolitic affinity, silt-stones and pelites). At the footwall of the massive banded ore (pyrrhotitesphalerite>galena>arsenopyrite and chalcopyrite), a stockwork of sulphide stringers interconnecting thin layers of sulphides are ubiquitous. A quartz-chlorite alteration is present. Chloritites are found below and laterally to the massive ore. All these features pre-date the Variscan tectono-metamorphism (up to 2.4 kbar and c. 400℃). The well preserved primary features are evidence for a very early (syn-sedimentary) stage of sulphide deposition and related alterations close to the sea-floor. The Hajjar deposit bears much similarities with the massive sulphide ores of the South Iberian Pyrite Belt that are considered to be transitionnal between the VMS and Sedex class of deposits (Saez et al. 1999).