Third New Epithermal Gold Zone at Las Calandrias Gold-Silver Project, Santa Cruz, southern Argentina
Mariana Resources Ltd ('Mariana' or 'the Company'), the AIM quoted exploration and development company focused in Argentina and Chile, announces positive results from scout drilling at the Nido Norte prospect, one of several key target areas at the Company's 100% owned Las Calandrias Gold-Silver Project ('Las Calandrias'), located in the prospective Deseado Massif gold-silver district in Southern Argentina. Sixty-two holes for a total of 9,650m have been drilled during this third drill campaign at Las Calandrias.
Overview
* Third epithermal gold zone discovered at Las Calandrias in the Nido Norte rhyolite dome complex;
* Results from 12 exploratory drill holes within a 750m section of the 1.8km long La Despreciada vein-breccia structure confirm the Nido Norte prospect as a prime target for follow up drilling;
* Best epithermal vein-breccia intersections include: 26.3m @ 1.0 g/t Au and 8 g/t Ag from 55m, 2.0m @ 3.9 g/t Au and 6 g/t Ag from 33m; and 2.2m @ 1.4 g/t Au and 59 g/t Ag from 106m;
* Mineralisation intersected along the La Despreciada vein-breccia structure is typical of an intact high level epithermal system and is centred on the large 2km x 0.6km Nido Norte rhyolite dome complex, possibly the largest in the dome field;
* Follow up drilling is now testing this 1.8km zone for higher grade targets at depth;
* Several prospective structures from ground magnetics provide new focus for Nido Norte and Calandria Norte type structure-hosted vein-breccia epithermal mineralization;
* Further assay results are awaited from scout drilling of other El Nido targets including Nido Sur and Gamekeeper prospects;
* Calandria Norte target - further bonanza silver intersections at La Morena Vein and high gold assays from La Calandria Vein were received with follow up drilling planned on both vein systems;
* Calandria Sur bulk tonnage target - exploratory drilling underway at the disseminated gold-silver discovery targeting subsurface rhyolite domes in the immediate vicinity of known mineralisation - maiden resource due by the end of April 2011.
Commenting today, Chairman John Horsburgh said, "These latest results from scout drilling at the Nido Norte target confirm the prospect as a prime target for follow up drilling. Mineralisation intersected is considered by Mariana geologists to be consistent with the upper parts of a high-level epithermal precious metal system. Consequently, deeper exploration drilling along the 1.8km Despreciada vein-breccia structure is underway to further investigate the epithermal gold vein system and its bonanza grade potential. Additionally, the structural setting at Nido Norte and Calandria Norte enhances the potential of a number of unexplored structures across the dome field."
Nido Norte
Dome-hosted mineralisation at Nido Norte was intersected in all twelve holes received with encouraging gold/silver values in nine of them. The drilling has tested the target structures mostly in a vertical range of 17m to 60m below surface. A broad zone of mineralisation related to chalcedonic breccias up to 3m wide and sulphide stockwork halo (30m wide) was intersected in exploration hole NND162 - 26.3m @ 1.0 g/t Au and 8 g/t Ag from 55m, including 1.6m @ 5.2 g/t Au & 71 g/t Ag from 64.5m.
The Despreciada mineralisation has no surface expression from mapping and reconnaissance rock chip sampling along the strike of the vein. In addition, petrological studies indicate the mineralisation at Nido Norte is a higher level in the epithermal system compared to the Calandria Sur target. High grade mineralisation at La Calandria vein in the nearby Calandria Norte dome also has minimal surface expression but commences from 50 to 90m below surface.
The twelve Nido Norte intersections included:
Hole NND154 - 2.0m @ 3.9 g/t Au and 6 g/t Ag from 33m
Hole NND155 - 1.7m @ 1.8 g/t Au and 9 g/t Ag from 39m
Hole NND156 - 14.0m @ 0.6 g/t Au and 8 g/t Ag from 34m
Hole NND157 - 6.7m @ 0.8 g/t Au and 12 g/t Ag from 66m
Hole NND154 - 2.0m @ 3.9 g/t Au and 6 g/t Ag from 33m
Hole NND162 - 26.3m @ 1.0 g/t Au and 8 g/t Ag from 55m
Hole NND164 - 6.5m @ 0.4 g/t Au and 2 g/t Ag from 10m
Hole NND167 - 5.0m @ 0.6 g/t Au and 11 g/t Ag from 85m
Hole NCD175 - 1.5m @ 2.1 g/t Au and 17 g/t Ag from 176m
Hole NCD178 - 2.2m @ 1.4 g/t Au and 59 g/t Ag from 106m
Hole locations and cross-sections are shown on the drill plans (see figures) and a summary of intersections is included in the table at the bottom of this release. Assays results are awaited for a further 28 holes drilled to date along the Despreciada structure for a total of 4,624m.
Calandria Norte
Remaining assays were received for four holes at La Morena and five at La Calandria veins within the Calandria Norte target area. CND139 intersected a wide zone of stockwork veinlets in the hanging wall of the eastern part of La Calandria Vein assaying 45.6m @ 0.4 g/t Au. Hole CND141 intersected a stockwork halo in the western part with 16.5m @ 0.5 g/t Au and a vein breccia assaying 0.5m @ 9.8 g/t Au. Two deeper holes (CND 149 and 150) intersected a stockwork vein halo with low gold and silver values.
An updated gm-m Au longitudinal section (gm Au x metres, see figure) shows the vein system extending over at least 400m strike. NE trending vein-breccias (up to 1.5m wide) dip steeply NW and plunge at a shallow angle to the SW within a broad stockwork zone up to 100m wide. Further drilling will target extensions to previously announced intersections of 8.0m @ 2.2 g/t Au from 91m (CND129), 7.0m @ 5.6 g/t Au from 120.5m (CND131), 0.8m @ 90.2 g/t Au and 198 g/t Ag from 132.1m (CND132) and 13.5m @ 3.0 g/t Au from 159m (CND137).
Remaining assays for four holes at La Morena Vein in the northern part of Calandria Norte dome returned 1.0 m @ 0.1 g/t Au and 981 g/t Ag from 140 m (CND153) and 0.5m @ 3.5 g/t Au and 44 g/t Ag from 71m (CND153) with follow up drilling planned.
Other El Nido Targets
The 2010 ground magnetic survey provides a new focus for a number of untested structures across the dome field prospective for Nido Norte and Calandria Norte style mineralisation. Results are awaited for a total of 21 holes testing Induced Polarisation ('IP') targets in other El Nido target areas at Nido Sur and Gamekeeper. No significant assays were received for seven scout holes at the Nido Oeste target area.
Calandria Sur
Resource modelling is underway by consultants Mine Development Associates ('MDA') of Reno, Nevada. Preliminary metallurgical test work being undertaken at Metcon Laboratories in Sydney, Australia, under the supervision of Consulting Metallurgist Peter Lewis, is outlined in the NI 43-101 technical report on Las Calandrias Project by MDA 24 November 2010 (see website). Test work has included LeachWell assaying, preparation of bulk composites, gravity concentration, carbon-in-leach tests and heap leaching of the oxide mineralisation. Tests on primary mineralisation have included fine grinding, flotation, oxidation of the flotation concentrate and cyanidation of the oxidised concentrate. The final test results and report are expected in March/April 2011.
Las Calandrias Project Background
Las Calandrias comprises multiple zones of gold mineralisation hosted by rhyolite domes over a 10.5km2 area. In 2009, 16 scout holes (1,763m) tested the Calandria Norte vein- breccia and Calandria Sur dome breccia targets where significant gold mineralisation was discovered (see news release 28 October 2009). The Q1/Q2 2010 drill programme consisted of 4,400m in 37 holes and tested Calandria Sur (28 holes/3,212m); Calandria Norte (2 holes/299m), El Nido Este (2 holes/309m) and El Nido Norte (5 holes/580m). The Q3 2010 programme consisted of 14,004 m in 110 holes; Calandria Sur (56 holes/6,186m); Calandria Norte (43 holes/6,175m); Nido Norte (7 holes/1,054m); Nido Oeste (2 holes/421m); La Herradura (2 holes/168m).
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