Horizon 1 1 17 ACLN : Articles dans des revues avec comité de lecture non répertoriées par l'AERES Mineralium Deposita 94-97 GEOCHIMIE OR GITOLOGIE MINERALOGIE PARAGENESE BRESIL GOIAS MARIA LAZARA REGION 1994 fdi:41481 ENG Mineralium Deposita 0026-4598 29 https://www.documentation.ird.fr/hor/fdi:41481 https://horizon.documentation.ird.fr/exl-doc/pleins_textes/pleins_textes_6/b_fdi_35-36/41481.pdf Horizon (IRD) The Maria Lazara gold deposit in the Archaean Guarinos greenstone belt, central Brazil, consists of quartz-carbonate veins formed in a ductile shear zone. Study of the sulphides and gold-bearing quartz-carbonate veins and veinlets of the potassic hydrothermal alteration zone reveals two stages of ore paragenesis. The first stage corresponds to S-rich arsenopyrite deposition and the second one to the precipitation of As-rich arsenopyrite and Bi-Te-Au-S phases. Modes of occurrence, textures and Ag contents of native gold define two types of gold. The first type is native gold with Ag contents greater than 5 wt % postdating the S-rich arsenopyrites. The second type has Ag contents less than 3 wt % and is contemporaneous with Bi-Te-S phases. (Résumé d'auteur) 064GEOCHI