Malbex Resources Inc. (TSX VENTURE:MBG) announced results today from five holes at the Rojo Grande target on the Company's Del Carmen gold-silver project in San Juan province, Argentina.
Near-surface gold-silver mineralization has now been identified over a strike length of approximately 500 metres at Rojo Grande, and remains open along strike and at depth. The Rojo Grande target consists of reddish, iron oxide-stained silicified rocks hosting gold-silver mineralization on the north side of the massif that cores the Del Carmen Norte hydrothermal alteration system.
"As our drilling program continues to expand the Rojo Grande mineralization, we're encouraged by its continuity, generally shallow depth and strong gold recovery shown in preliminary metallurgical testing. Additionally, today's results show the potential for higher grade zones," said Tim Warman, President and CEO. "While we still need to demonstrate an economic resource through more drilling, Rojo Grande is beginning to show potential for a low-cost open-pit, heap leach mining scenario."
With today's release, seven holes totalling 1,258 m have been reported of the 10,000 metres budgeted for the 2010/2011 field season at Del Carmen Norte. Drill production has been slower than anticipated, which will likely result in completion of less than the 10,000 metres planned for this season. Malbex is working closely with the drilling contractor to improve production, and expects to complete sufficient drilling at Del Carmen Norte to support an initial resource calculation at Rojo Grande and to test several geophysical targets identified in the last field season.
The first hole designed to test the large geophysical anomaly between Cerro Amarillo and Rojo Grande was lost prior to reaching the target depth, and a new hole targeting the anomaly has been started from a nearby drill pad. The target depth for these holes is approximately 500 m.
Today's results
DDHC-10-035 (azimuth 310°, dip 70°) intersected mineralization below and to the south-east of DDHC-10-020. Mineralization occurs below the silicified ledge within advanced argillic (quartz-kaolinite) altered volcanic rocks. This hole encountered some of the highest grades intersected to date at Rojo Grande including 8.0 metres at 7.08 g/t gold and 11.6 g/t silver (7.27 g/t Au-EQ).
DDHC-10-036 (azimuth 310°, dip 50°) and DDHC-10-038 (azimuth 090°, dip 60°) represent the southwestern-most drill tests at Rojo Grande. DDHC-10-036 did not intercept significant mineralization. The hole encountered variably advanced argillic (quartz-kaolinite) altered volcanic rocks with only minor development of silicification and vuggy silica with one short zone of low grade mineralization. The hole is interpreted to pass above the CSAMT resistive anomaly coincident with the shallow northwest-dipping silicified ledge. DDHC-10-038 was drilled to the east to cross a fault mapped on surface at a high angle before intersecting the silicified ledge and this hole contained two +20m long mineralized intervals, including 24 m grading 1.12 g/t Au-EQ. The cross section showing both holes is non-planar and the geological interpretation of this area of Rojo Grande remains in progress.
DDHC-10-037 (azimuth 140°, dip 50°) intersected near surface low grade mineralization in strongly silicified volcanic rocks that are truncated by a northeast-trending fault zone that defines the south-eastern margin of the silicified ledge. DDHC-10-039 was a vertical hole on the same section as DDHC-10-037, and these holes constitute the northeastern-most intersections of Rojo Grande mineralization. DDHC-10-039 encountered 86 metres of gold-silver mineralization grading 0.77 g/t gold and 9.3 g/t silver in moderately to strongly faulted (brecciated) rocks. The mineralization remains open to the northeast and at depth. Geological interpretation of the controls on mineralization in this area is ongoing.
Del Carmen Norte and Rojo Grande
Rojo Grande consists of prominent reddish weathering silicified outcrops on the northern flank of the massif of high sulphidation hydrothermal alteration at Del Carmen Norte. Silicified outcrops and geophysical data identify a shallow-dipping NE-SW striking, near-surface silicified ledge at Rojo Grande measuring approximately 800 m long by up to 300 m wide. Six diamond holes at Rojo Grande in the previous campaign intersected near-surface gold-silver mineralization in silicified rocks over an area about 200 m by 150 m.
Previous significant intersections at Rojo Grande include:
- DDHC-10-017: 41 m grading 1.18 g/t gold and 31.2 g/t silver
- DDHC-10-018: 15 m grading 1.07 g/t gold and 27.3 g/t silver
- DDHC-10-020: 124.5 m grading 0.57 g/t gold and 8.8 g/t silver
- DDHC-10-031: 38 m grading 0.88 g/t gold and 12.2 g/t silver
- DDHC-10-032: 142.15 m grading 0.88 g/t gold and 13.7 g/t silver
- including 40.15 m grading 1.45 g/t gold and 17.4 g/t silver
- DDHC-10-034: 73 m grading 0.74 g/t gold and 31.2 g/t silver
Mineralization at Rojo Grande is generally hosted by vuggy silica and massive silicification with fine-grained hematite, goethite and jarosite veinlets and red-brown staining. Selective chip sampling of northeast-striking zones of hydrothermal breccias cemented by chalcedony and very fine-grained quartz that cut pre-existing silicification yielded samples with up to 10 g/t gold.
The silicified reddish outcrops at Rojo Grande are interpreted to be part of a sub-horizontal ledge (sheet) formed by preferential silicification and quartz-alunite alteration of volcanic breccias within the strongly argillic (illite) to advanced argillic (kaolinite) altered tuffs and fine-grained flows that dominate the andesitic volcanic sequence. The alteration is cut by northeast-, north-northwest- and east-striking fault zones. The mineralized intersections are bounded by changes in style of alteration, by faults or both. While some faults abruptly truncate silicification and thereby clearly post-date the hydrothermal events, hydrothermal feeder structures that controlled alteration and mineralization are inferred to preferentially coincide with one or more of these directions.
Del Carmen work program
The 147 km2 Del Carmen concession package is located near the southern end of the El Indio Gold Belt, and hosts the Del Carmen Norte and Del Carmen Sur high sulphidation epithermal gold-silver systems. The Del Carmen Norte hydrothermal alteration system covers approximately 9 km2. A second, less exposed, high sulphidation epithermal system occurs at Del Carmen Sur some 5 km to the south of Del Carmen Norte.
Del Carmen Norte consists of a strongly altered, sub-horizontal sequence of andesitic volcanic rocks that is cut by numerous faults. Volcanic breccias appear to be selectively silicified with silicification hosting mineralization sandwiched between less favourable argillic altered volcanic layers. Steep faults have strongly influenced hydrothermal fluid flow within the volcanic sequence. High-sulphidation alteration is therefore zoned outward from the combination of both lithological and structural controls on silicification. Controlled source audio-magneto-telluric surveying (CSAMT) in the previous field campaign identified elevated resistivity coincident with silicified rocks at Rojo Grande. Other larger CSAMT resistivity anomalies to the southwest are directly associated with steam-heated siliceous alteration at high elevations at Cerro Amarillo but continue to the depth limits of detection of the survey (roughly 500 m vertically).
In addition to Rojo Grande, other zones of vuggy silica and other styles of silicification, and enargite-bearing quartz veins on surface were drill tested in the 2009-2010 field campaign. The current drilling campaign at Del Carmen Norte will focus on defining the extent of gold-silver mineralization at Rojo Grande, testing CSAMT resistivity anomalies (including the large anomaly between Rojo Grande and Cerro Amarillo), and following up on encouraging initial drill results from Naciente Quebrada Pedregosa.
Technical information
Diamond drill hole samples consist of HQ-3 (6.11 cm diameter) core that is sawn in half by electric saw on site. Core samples are sealed in new plastic bags, which are inserted into rice sacks for transport by Malbex personal or commercial trucking service to ALS Global prep lab in Mendoza. All samples are crushed and pulped and powders sent by ALS to one of their laboratories (typically La Serena, Chile or North Vancouver, BC). Fire assay for gold is conducted on 30 gram (g) pulps with atomic absorption finish. Over limits (>10 g/t gold) are fire assayed with gravimetric finish. In addition, all samples receive multi-element analysis including silver by ICP after aqua regia digestion and mercury by cold vapour atomic absorption.
Malbex's quality assurance-quality control (QA-QC) program consists of the insertion in every 20 samples of at least one certified standard of known gold content, one blank (sample known to consist of very low levels of gold to ensure adequate cleaning of the sample preparation equipment between samples) and one field duplicate. Samples of significant drill intercepts will be sent to two additional independent laboratories to verify gold and silver analyses when necessary. Metallic screen fire analyses for gold will also be run regularly on discovered mineralization as an additional QA-QC check. The half core remaining after sampling is stored in a Malbex-run facility in San Juan for verification and reference purposes.
Peter Stewart, PhD, Vice-President Exploration of Malbex Resources Inc., is a Professional Geoscientist in the Province of Ontario, and is the Qualified Person as defined by NI 43-101 responsible for the technical information presented in this news release.
Source: Malbex Resources Inc.