The Maricunga and the El Indio Belts in Chile’s Andean Cordillera host a number of the larger gold deposits in Chile. Since 1980 a total of 40 million ounces of gold have been identified in the region in a series of large porphyry-style deposits, each containing several millions of ounces of gold and silver. Porphyry deposits are often associated with an overlying lithocap of highly altered volcanic rocks.
The Falda Project lies in the Maricunga Belt. The highly-altered Falda lithocap is composed of a major unit of volcanic breccia and thin sequences of bedded tuffs. The two hills making up the original exploration target at La Falda (Falda Norte and Falda Sur) show the distinct white, yellow and red colour anomaly typical of advanced alteration of the original volcanic rocks which is often indicative of epithermal gold mineralisation. Several near-vertical, silicified breccia structures cutting across the lithocap carry anomalous levels of gold, silver, arsenic and lead. In this geological setting structures such as these can carry high grade epithermal gold mineralisation at depth. Drilling is planned investigate the epithermal system to appropriate depths, deeper than an earlier phase of drilling by previous owners.
In addition to the potential epithermal mineralisation, Catalina has discovered two porphyry intrusives (Porphyry Norte and Porphyry Central) in two hills immediately to the west of the La Falda lithocap. These host a series of distinctive narrow banded quartz vein stockworks that carry gold.
A third porphyry occurs to the south although no such mineralisation has been observed there to date. The quartz veins are very similar in appearance and grade to those which host ore-grade mineralisation at the Refugio and Marte mines and the Volcan exploration project - 60 to 100 km to the south of Falda.
By analogy, the main exploration target at La Falda is now a multi-million ounce near-surface gold-porphyry with associated epithermal gold-silver mineralisation. The potential target size can be extrapolated from Kinross’ Maricunga Mine, Lobo-Marte and Cerro Casale deposits; Andina Minerals’ Volcan Project and Exeter Minerals Caspiche deposit – see table below.
| Deposit / Mine | Owner | Category | Tonnes (Mt) | Gold (g/t) | Gold (M Oz) | Copper (%) | Copper (Mlb) | |
|---|---|---|---|---|---|---|---|---|
| Maricunga | Kinross | Reserves & Resources | 111.45 | 0.63 | 2.27 | |||
| Volcan | Andina | Total Resources | 337.1 | 0.87 | 9.38 | |||
| Lobo-Marte | Kinross | Total Resources | 106.93 | 1.71 | 5.87 | |||
| Caspiche | Exeter | Inferred | 449.8 | 0.6 | 8.73 | 0.21 | 2,091 | |
| Cerro Casale | Kinross | Reserves & Resources | 1,665.33 | 0.54 | 28.78 | 0.21 | 7,751 |
At most of the Maricunga mines, erosion has removed the upper parts of the lithocap and exposed the deeper structures which carry economic gold mineralisation. In contrast, the Falda Norte and Sur areas show very little erosion. The porphyry intrusives and their associated gold mineralisation appear to have been preserved almost intact.
Geophysical surveys - ground magnetics and IP - have been completed and confirm the geological model.
Ground magnetic data has outlined a large (approximately 2 km by 1 km) weak magnetic high in and around the underlying intrusive. Magnetic highs (pink) are due to the presence of magnetite and are often flanked and cut by strong magnetic lows (dark blue) which may represent areas where alteration associated with the mineralising process may have destroyed magnetite. Similar patterns are observed in other Maricunga porphyries.
The Induced Polarisation survey has revealed a promising target zone (approximately 2 km E-W by 600 m N-S) within a larger 2.4 km by 2 km chargeability anomaly which encompasses the entirety of the magnetic anomaly. Sulphides are associated with large geological features (an intrusive porphyry?) as opposed to simple linear fracture/breccia zones. A second promising target zone is a zone of higher resistivity within a circular zone of low-resistivity. The zone includes most of the weak magnetic high anomaly and the chargeability anomaly.
A deep high-resistivity zone measuring approximately 1 km by 400 m and possibly indicative of silicification (and gold?) is well-defined on the 4100-m elevation resistivity plan.
The chargeability anomaly is consistent with the presence of sulphides below a depth of approximately 100m - persisting to at least 350-400m indicate extensive sulphides beneath both the lithocap and the porphyry intrusives.
Drilling will start at the Porphyry Norte sector and step out along the strike of the anomalies.
On 31 March 2009 Catalina and AIM-listed Minera IRL Limited (“MIRL”) announced the signature of a Letter of Intent (“LOI”) to form a Joint Venture with Catalina Resources over the La Falda Project. After completion of a definitive Joint Venture agreement before 31 August 2009, MIRL will spend US$3.7 million on exploration and property acquisition payments to perfect a 75% interest in the project.
