Guatemala City, Guatemala — Trench-sampling over 15 sq. km of the El Tambor project in Guatemala has outlined a new gold discovery for junior
Over the past year, the Simon Ridgway-led company has focused its attention on developing multiple new gold zones in a previously unrecognized and unexplored gold belt.
“We’ve had six to eight geologists working on the project for over 14 months,” Radius Vice-President Robert Wasylyshyn told The Northern Miner during a site visit.
The junior has zeroed in on the Montagua fault, a major crustal shear zone that bisects central Guatemala, separating a younger volcanic belt to the south from older basement rocks in the north. The Tambor property is only 5 km south of this zone of crustal weakness.
The project covers a series of low-sulphidation, epithermal gold zones hosted by highly deformed Paleozoic-aged schists. Situated 50 km north of Guatemala City and 700-1,100 metres above sea level, it is easily accessible via paved road.
Gold mineralization is hosted by the Tambor Group Schist, the same stratigraphic package that hosts the San Martin gold mine in Honduras. San Martin was discovered by the Ridgway-Wasylyshyn team in conjunction with Mar-West Resources. In many ways, El Tambor is similar to San Martin. Both are associated with low-angle structures, and, at each, mineralization is hosted in oxidized Paleozoic-aged schistose rocks. In addition, both sites are spatially associated with hot-spring systems, suggesting epithermal origin.
San Martin was eventually sold to Glamis Gold in 1998 for $48 million and is currently in production. This year, the mine is expected to pour 113,000 oz. gold at a cash cost of US$113 per oz. The average gold grade at San Martin is 0.9 gram gold per tonne.
After a brief stint with Glamis, the principals of Mar-West turned their attention toward managing Radius Explorations. In December 1999, the junior acquired the right to a 100% interest in the El Tambor gold prospect in central Guatemala. In return, the company agreed to pay a subsidiary of
To date, Radius has spent in excess of $1.5 million on the El Tambor property. Extensive ash cover, combined with thick vegetation, has made prospecting difficult; however, company geologists have managed to prospect the 66 sq. km property and collect more than 2,100 rock samples, 3,000 soil samples and 500 silt samples.
In addition, Radius has applied for more than 2,000 sq. km of new concessions adjacent to the Motagua fault and along strike of the structural and geological setting at El Tambor. Once these applications are granted, Radius will hold a 100% interest in these new land packages.
“This part of Guatemala has never seen a rock hammer,” noted Wasylyshyn.
Preliminary reconnaissance work on the La Lagoona prospect, 10 km west of the Bridge prospect, has already revealed anomalous gold concentrations.
Five zones
Exploration work at El Tambor has identified five significant gold zones that seem to be related to a low-angle fault structure known as the Tambor Shear zone. This structural zone trends east-west and dips gently to the north at about 8. The mineralization discovered to date in this shear zone is distributed over an area that measures 6 by 2.5 km.
The gold is hosted in strongly deformed and brecciated units within the Tambor shear. These rocks are oxidized and friable, with a low silica content. Chlorite and sericite schists seem to be the dominant host rock. Mica schists and meta-sediments become more prevalent as one moves west, toward the Bridge zone. Gold mineralization tends to be associated with silica veining and agillization, as well as carbonate flooding.
Late in 2000, Radius conducted extensive trenching over the five most prospective zones: Sastre, Bridge, Lupita, Valery and TBS. These zones range in thickness from 10 to 50 metres and average 25 metres. Geochemical evidence indicates that some of these mineralized “pancakes” may be stacked.
The Sastre zone, which is about 500 metres long and has a true thickness that ranges from 11 to 24 metres, currently hosts the highest grades on the property. Several old tunnels and exploration pits have been found. A grab sample of float material taken from one of the exploration pits assayed 350 grams gold per tonne. A sample from a tunnel driven on a low-angle breccia yielded 14.5 grams gold. At this spot on the property, the mineralized zone appears to be tilted to the southwest at about 30. Wasylyshyn postulates that this may be due to block faulting.
The Sastre zone has been cut by five trenches, results are as follows:
– Trench S-1 intersected 14.2 metres grading 5.54 grams gold and remains open.
– Trench S-2 cut 11.25 metres grading 4.09 grams and remains open.
– Trench SN-1 cut 29.4 metres grading 10.60 grams gold.
– Trench SN-4 intersected 24 metres grading 2.09 grams gold.
– Trench SN-5 cut 20 metres grading 10.52 grams gold.
Vertical trenches
All of the trenches at Sastre are vertical, and the sample intervals represent the true thickness of the zone. Trenches SN-2, 3 and 6 were all dug on the western side of the Sastre ridge and returned only narrow zones of mineralization. Radius now believes that these trenches tested the hangingwall of the shear zone.
The Lupita zone is about 250 metres west of the northern end of the Sastre zone. This mineralized unit ranges in thickness from 8 to 45 metres and has been traced by rock and soil geochemistry for more than 1,000 metres. The surface expression of the unit snakes its way toward the southwest, following a ridge line. To date, nine trenches (all vertical) have been dug, and sample widths represent the apparent true thickness of mineralization. Results are as follows:
– Trench LW-1 cut 18.2 metres grading 1.57 grams gold and remains open.
– Trench LW-2 intersected 23.6 metres averaging 2.41 grams gold.
– Trench LW-3 cut 19.2 metres grading 1.8 grams gold and remains open.
– Trench LW-4 cut 21.5 metres grading 1.31 grams gold and remains open.
– Trench LW-5 cut 5.5 metres averaging 1.87 grams gold.
– Trench CH-1 cut 45.9 metres grading 0.9 gram gold and remains open.
– Trench CH-2 cut 21 metres grading 1.45 grams gold.
– Trench CH-3 intersected 28 metres averaging 0.6 gram gold.
– Trench CH-4 cut 18 metres grading 0.67 gram gold.
The Valery zone is about 1 km southwest of the Lupita zone. Here the gold mineralization is exposed on a hillside and forms the dip-slope of the hill for a distance of 250 metres before it is lost under cover. Four trenches were completed at the Valery site, each of which tested an area measuring 250 by 300 metres. Trenches VA-2, VA-3 and VA-4 were dug vertically, and sample intervals represent the true thickness of mineralization. Trench VA-1 was dug along the horizontal. Results are shown below.
– Trench VA-1 cut 65 metres grading 1.47 grams gold.
– Trench VA-2 cut 25 metres grading 2.48 grams gold and still remains open.
– Trench VA-3 cut 21 metres grading 0.85 gram gold and remains open.
– Trench VA-4 cut 18.5 metres grading 1.46 grams gold and remains open.
The Bridge zone is 1.7 km west of the Valery zone and lies at the bottom of a river valley. This zone was the first prospect discovered by the Radius team. Chip sampling along the banks of the river yielded 3.89 grams gold over 75 metres. Initial sampling across the river, along an old railway cut, returned 2.6 grams over 65 metres.
Recent trench results in the same area yielded 85 metres grading 3.59 grams gold, as well as 65 metres of 2.58 grams gold.
True thickness unknown
Mineralization at the Bridge zone outcrops over a known strike length of 400 metres and is open in all directions. Unconsolidated volcanic ash blankets the mineralization above the river valley; however, hand-trenching has confirmed that the mineralized unit underlies the ash cover. All trench results from the Bridge zone are cut along-strike on horizontal exposures, so the true thickness of the mineralization is still unknown.
The TBS zone, 1,000 metres southeast of the Sastre zone, is undergoing trenching. To date, 150 rock and chip samples have been taken from the prospect. These average 1.75 grams gold.
Just west of the TBS zone lies the Escondida prospect, which hosts five zones of mineralization. Near the bottom of the hill, chip samples from a 16-metre trench averaged 5.4 grams gold per tonne. At the top of the prospect, an 8.5-metre trench averaged 3.4 grams gold. The total height of the Escondida zone is 70 metres.
Prior to releasing the trench results, Radius geologists re-sampled many of the higher-grade trenches at smaller intervals to test for inhomogeneous gold distribution or nugget effect. “The numbers are holding together,” commented Wasylyshyn. “There are no spikey veins; the gold grades are very consistent.”
Supergene enrichment of the mineralization is another concern in tropical regions. However, Wasylyshyn says that until the prospects are drilled, there is no definite way to determine the extent of enrichment. Radius intends to begin a first phase of drilling before mid-year. The program will likely focus on the Bridge and Sastre zones.
El Salitre
Meanwhile, at the El Salitre project, in Mexico,
El Salitre is centred on a gold-enriched hot springs system related to a large graben fault. The fault can be traced for at least 35 km, and mineralization is associated with three sinter bodies that cover 3.5 km of strike length. A first-phase exploration program defined two gold anomalies: one at the Salitre zone, and the other at the Bartolome zone.
High volumes of hot water posed problems for Radius at the drilling stage. At the Salitre zone, for example, only three short holes totalling 209 metres could be completed. All three holes intersected anomalous gold values with associated silver, arsenic, zinc and antimony. The best values were encountered in hole ESRC-2, which returned 0.7 gram gold over 13.7 metres.
The Bartolome zone was tested by five holes, which totalled 1,099 metres. All the holes cut anomalous gold values associated with zones of quartz veining; however, gold values were weak and the mineralized zones, narrow. The strongest intersection was 0.4 gram gold across 15.3 metres.
At last report, Radius had 10.7 million shares outstanding, 15.2 million fully diluted and $1.5 million in its coffers.
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