Calcatreu Project 3D vein modelling, Río Negro Province, Argentina

MATÍAS SEBASTIÁN WERNERT; DARÍO VERA; MARCELO PAOLINI; DIEGO GUIDO; SEBASTIÁN MIGUEL JOVIC

Londres

Conferencia; SEG 2023 Conference: Resourcing the Green Transition; 2023

Society of Economic Geologists

TheCalcatreu Project is a low-sulphidation epithermal Au-Ag deposit located in RíoNegro Province, Argentina, currently undergoing advanced exploration stages.Indicated resources are estimated at 746 kOz, with ore grades of 2.36 g/t AuEq.Thedistrict is located in the Somún Curá Massif, a geological provincecharacterized by extensive Jurassic vulcanism related to extensional eventslinked to the Gondwanide Orogeny. This sub-explored region bears similargeological features and mining potential with the important low-sulphidationDeseado Massif province.Thedeposit hosts an array of NE-SW trending quartz-carbonate veins, hosted byJurassic andesites and tuffs. Furthermore, the district is intersected by theGastre Fault Zone, a Jurassic NW-SE regional megastructure that controlled veindisposition. The main gold ore is electrum, mostly linked to an openspacefilling pulse comprised of silica, carbonate, adularia, and ginguro bands.Themain exploration targets are Nelson E, Nelson W and 49 veins, where extensivemapping, drilling and geophysical surveys were conducted. This data was used tocreate a 3D geological model of the ore bodies by employing Leapfrog software.Themineralization took place under σ1 stresses of an approximate 60° Norientation. The ore bodies follow an overall NE-SW orientation and a 60° to80° SE dip. Specifically, the main veins trends vary between 40° to 80° N,whereas related splays and offshoots fall between 0° to 30° N ranges.Vein 49 features a well-defined1 km long strike with few secondary ramifications. Normal faulting with varyingshear stresses occurred during mineralization, as evidenced by slickenlineswith rake angles between 40° to 80° E. Post-mineral faulting is also present,as suggested by common vein displacements. A major E-O structure limits Vein 49with the southern Nelson targets, which consists of a 2 kilometre-wide veinswarm that defines a mesh-type architecture.