Geology

Regional Geology

The project area is underlain by early to mid-Cretaceous andesites, rhyolitic tuffs, ignimbrites, arenites and quartzites which have been intruded by upper Cretaceous to lower Tertiary calc-alkali granodiorites, dacites, monzonites, and aplites.

The bulk of the volcanic rocks existing along the main mineralised trend are rhyolitic in composition, and quite siliceous in character. Dacites and andesites are also present interlayered with the rhyolitic volcanics.

Project Geology

The Productora project area secures a NNE-trending fault zone which is an interpreted splay off the Atacama fault zone (AFZ), 5kms to the west. Metasomatic and hydrothermal alteration is widespread and intense, associated with late Cretaceous to early Tertiary movement along the NNW-SSE Atacama Fault Zone.

The host rock sequence for the Productora mineralisation is a rhyolitic breccia (based on exposures near the Santa Innes mine). Metasomatised granitoid intrusions are evident in outcrop to the south and east of the mineralised zone. The granitoids are interpreted to be middle-Cretaceous to early-Tertiary in age (Fortin, 1990). Andesitic to latitic dykes cross-cut the host sequence. These rocks tend to be far less altered than the host sequence suggesting they were emplaced relatively late in the geological history.

Geochemical work completed has recognised two zones of intense copper, gold, molybdenum, cobalt and uranium–associated metasomatic surface alteration along the main NNE-trending mineralised trend: one at Productora (central area) and one at Carmen (northern area).

There is a distinct metal association comprising copper, gold, molybdenum, cobalt, uranium, silver, vanadium, bismuth and phosphorus.

 Alteration

The following alteration, structural observations and mineralisation styles and interpreted controls were documented by Dr J. Beeson during his 2009 field reconnaissance review of the project.

Silicification with pyrite and chalcopyrite is accompanied by potassic alteration (K-feldspar), argillisation, tourmalinisation, iron-oxide alteration and sericitisation. This pattern of alteration and mineralisation suggests that it is a member of the IOCG mineral system.

There is an obvious zonation of alteration mineralogy from K-feldspar-tourmaline in the south to chlorite-K-feldspar-carbonate in the north which probably reflects a temperature gradient. The alteration mineralogy suggests a cooling of the system northwards and probably also indicates a gentle northerly plunge to the hydrothermal system.

Structural Controls & Observations

Changes in strike are obvious along the Productora fault zone. These are expressed as discrete clockwise jogs where the fault locally changes from a N-S orientation into a NNE orientation. Such jogs in the fault zone represent interesting areas as they are likely to be associated with wider damage zones which promote increased secondary permeability suitable for focusing hydrothermal fluids. The Productora fault trends NNE in the area between the Productora and Santa Innes mines; thus these mineralised zones are located broadly proximal to either end of the NNE-trending fault jog.

A sub-parallel but slightly convergent regional fault has been mapped to the west of Productora. This structure is also associated with mineralisation (magnetite and copper). This more westerly fault trends more uniformly NNE and joins with the Productora fault approximately 2 km north of the Productora mine. The geometry of this more westerly structure is reminiscent of a splay off the Productora fault and is referred to as the Western Splay fault. Numerous abandoned copper workings are distributed along the trace of the Western Splay fault and many of these workings are weakly to moderately radioactive.

Numerous cross-cutting NW-trending faults have been documented in previous mapping. Many of these structures are associated with copper mineralisation and variably elevated radiation levels. In addition, numerous examples of E-W and N-E trending faults were observed; again these faults are commonly in association with copper mineralisation.

Mineralisation Styles & Controls

The association between faulting and mineralisation is very obvious at Productora. Primary mineralisation appears to rely upon the interplay of favourable lithological units (primary permeability), regional faults and cross faults (both providing secondary permeability). Sites where favourable lithological units coincide with cross-faults and with regional fault jogs (and adjacent damage zones) represent obvious targets for mineralisation. In addition, areas where regional fault splays bifurcate from the master fault, as is the case 2km north of Productora mine; appear to be associated with relatively large damage zones that contain many mineralised veins. The abundance of old copper shafts in the damage zone between the Western Splay fault and the Productora fault is relatively well mineralised and represents an obvious target for further exploration.