The mining newspaper for Alaska and Canada's North
Anomalies on central Alaska copper-gold-silver property may warrant aggressive follow-up; drilling at Livengood gets under way
International Tower Hill Mines Ltd. May 13 said the results from a recent high resolution airborne magnetic and EM survey completed over 30 square kilometers of mineralized areas of the company's BMP project in central Alaska show huge anomalies that warrant aggressive follow-up exploration.
A day earlier the Vancouver, B.C.-based junior announced the start of resource expansion drilling at the Livengood Gold Project 100 kilometers, or 60 miles, north of Fairbanks. The company plans to drill about 42,000 meters, 136,500 feet, in 150-175 holes within the core target area, which covers an area of about 1.5 square kilometers.
The junior plans to spend C$9 million on 2008 exploration in Alaska, including C$7.5 million at Livengood where it has identified a multimillion-ounce gold resource.
BMP features excite explorers
Earlier this year, Fugro, the company's contractor, completed an airborne magnetic and electromagnetic survey of the core target area at the BMP project, covering two blocks with nominal line spacing of 50 meters.
International Tower Hill said the surveys at BMP showed large geophysical anomalies spatially associated with the outcropping copper-gold-silver skarn deposits discovered in 2007.
The largest anomaly is associated with the 6120 target area and covers about 1 square kilometer forming at an important structural intersection on the south side of the core intrusive. Twenty rock samples collected from a 150-meter-diameter area of outcropping skarn at the 6120 target averaged 2.3 percent copper, 3.4 grams per metric ton gold, 33 g/t silver, 0.16 percent nickel and 0.07 percent cobalt. In addition, similar skarn-type mineralization was found 2 kilometers, or 1.24 miles to the north at the 6920 prospect.
The Dall and Little Bird prospects, located on the northern target block (about 5 kilometers north), also appear to be associated with skarn and distal skarn-type mineral systems. The Dall target was drilled by Anaconda Mining Company in the 1980s with two diamond drill holes, each of which intersected very significant high-grade mineralization-4.0 percent copper, 11.8 oz (370 g/t) silver, 1.0 percent zinc and 0.3 percent lead over a true thickness of 3.5 meters and 0.9 percent copper, 6.0 percent zinc, 5.7oz (177 g/t) silver and 1.0 percent lead over a true thickness of 5.5 meters.
In total, the past and recent work in this one relatively small area of the BMP land package suggest that the high-grade mineral system has a strike length of at least 8 kilometers, or about 5 miles, and that the Dahl-6120 target offers significant potential for discovery of a major new precious-metal-rich, base metal deposit, according to International Tower Hill.
"The size and dynamic range of the anomalies suggest that they are related to a large base- and precious-metal bearing hydrothermal system, which warrants aggressive follow-up exploration," the company said May 13.
High-grade zones confirmed in 2007
The BMP property is located 250 kilometers, or 155 miles, northwest of Anchorage, and about 40 kilometers, or 21 miles, north of the company's Terra project. It covers some 13,193 hectares, 3,869 acres, and is composed of 108 Alaska State mining claims staked in October 2006 and owned 100 percent by the company and about 6,200 hectares or 1,818 acres, of fee simple lands held under the exploration agreement with option to lease from Alaska Native regional corporation Cook Inlet Region, Inc.
The property is underlain by Paleozoic sediments which have been intruded by dikes and plugs of early Tertiary age. Exploration in 2007 confirmed a number of mineralized zones with numerous high-grade copper, silver, zinc and gold values being returned the company said.
This work linked much of the mineralization to a prolific skarn-type mineralizing environment and highlighted the potential of the belt. At the 6120 and 6920 prospects calcareous horizons have been extensively replaced by skarn mineralization, including massive pyrrhotite with chalcopyrite and sphalerite. High gold values are present at both of these prospects with grades of several grams in specific samples. Both prospects occur on the flank of a Tertiary intrusive body.
Drilling targets higher-grade zone
International Tower Hill said the resource expansion program at the Livengood property will focus on the higher-grade Lillian Zone of the deposit and is designed to double the size of the prospect's 2 million-ounce inferred gold resource (87.8 million metric tons at a grade of 0.71 grams per metric ton, using a 0.50 g/t gold cutoff). This is part of the global inferred resource of 3.3 million ounces of gold (188 million metric tons at a grade of 0.54 g/t gold using a 0.30 g/t gold cutoff).
The Lillian Zone has returned a number of higher grade intervals such as 8.8 meters of 9.95 g/t gold, 8.5 meters of 9.64 g/t gold and 3.5 meters of 7.33 g/t gold contained within thick (greater than 50-meter) intervals averaging greater than 1 g/t gold, the company said.
The grade-tonnage curve produced from the initial resource calculation using 48 drill holes indicates a significant potential to define a large resource at Livengood. With just 25 percent of the core target area drilled to date, the company said it considers the upside potential for the deposit to be "enormous."
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