抄録
A hidden porphyry copper deposit of primary ore has been discovered in Andes Mountains, southern Peru. The exploration works were initiated by aeromagnetic survey and interpretation of colored aerial photo followed by detailed geological mapping combined with geoche-mical and I.P. surveys. Thus Quechua was finally selected for diamond drilling.
The deposit, consisting of flat laying parallel veinlets with minor dissemination of chalcopyrite and garnet magnetite chalcopyrite skarn, occurs in a fracture zone, developed in Cretaceous sediments which are intruded by numerous flat laying dykes of porphyry. Wall rock alteration is characterized by carbonatization with moderate silicification while potassic alteration is rather weak.
These features suggest that the Quechua deposit was formed at offshoots far from a possible intrusive stock, and sulphide mineralization took place after solidification of porphyritic intrusives.
