Hunter Dickinson Inc. has set out to bring continuity to the disjointed picture that geologists have of the precious metals-rich Delta volcanogenic massive sulfide property in the eastern Alaska Range about 36 miles, or 58 kilometers southwest of Tok, Alaska.
Over the past 35 years, geologists representing a throng of mining companies have traversed the Delta project investigating the promising mineralization known to exist there. This exploration, which includes 23,711 meters of drilling, has discovered 40 mineral occurrences on the property, seven of which have had inferred resources calculated for them.
Re-examining and re-interpreting the disparate data was the first task for Hunter Dickinson’s geological team.
The privately-held company decided the best way to unify and expand the historical data is to fly a 725-line-kilometer versatile time-domain electromagnetic survey over the entire 61-square-mile, or 158-square-kilometer, property.
The response the geophysical survey returns over areas of known mineralization will provide a signature Hunter Dickinson geologists can use to delineate targets for a drill program expected to start in 2011.
“We are in the process of flying an airborne VTEM survey over the entire project, including the new claims we staked. We have done some forward modeling with the geophysics, and we feel pretty comfortable that the VTEM survey is going to give us some really good drill targets,” Interim Delta Project Manager Lena Brommeland told Mining News during an August 20 interview.
Segmented geologyThe VMS mineralization at Delta is nearly as segmented as its geological investigations. An inferred resource of 15.4 million metric tons grading 0.6 percent copper, 1.7 percent lead, 3.8 percent zinc, 62 g/t silver, and 1.7 g/t gold is distributed amongst seven deposits.
Four of the deposits in the resource – LP, MID, DW and VAL – are considered to be four sections of what was once a 3,200-meter-long sulfide sheet that has since been broken by faulting. According to an NI 43-101 report prepared for the project in 2006, these four zones, known as DW-LP, have the potential for significant expansion. While additional drilling would be needed to validate the concept, geologists believe this sulfide system could contain around 25 million metric tons with 0.6 percent copper, 2.2 percent lead, 1.9 percent lead, 5 percent zinc, 58 g/t silver and 2 g/t gold.
A fifth deposit, known as PP2, was originally thought to be a part of DW-LP sulfide sheet, but was later determined to be a deeper sulfide layer.. Not much is yet known about these lower strata of VMS mineralization.With gold grades that average 2.6 g/t, DDN and DDS contain significantly higher grades than the five other deposits included in the resource. These deposits, which are considered to be related, are open for expansion and have about 1,200 meters of untested area lying between them.
Trio and Supercub, two prospects not included in the resource, hold the promise for new high-grade discoveries at Delta
Originally thought to be massive sulfide outcrops, large boulders averaging 7.3 percent lead, 5.6 percent zinc, 113 g/t silver and 0.7 g/t gold led geologists to Trio. It was later determined that these stones and the surrounding region was part of a landslide area. The source of the sulfides has yet to be discovered.
Supercub, about 1,500 meters northwest of Trio, was also discovered with the help of massive sulfide boulders. These high-grade rocks, which average 25 percent combined copper, lead and zinc plus 200 g/t silver and 11.3 g/t gold, are believed to be transported by glacier from a location indicated by a geophysical anomaly. Only one hole, which did not cut massive sulfides, has been drilled in the prospective area.
New junior?Hunter Dickinson optioned the Interior Alaska VMS property through a joint venture with Grayd Resource Corp. A key part of the venture was expanding the property to 61 square miles, or 158 square kilometers, by staking an additional 238 claims.
The Vancouver B.C.-based company will hold a 60 percent interest in a limited liability company formed for the Delta joint venture by reimbursing Grayd for staking the additional claims, funding US$3 million in exploration by the end of 2012. Following the initial earn-in, Hunter Dickinson has the option to acquire Grayd’s 40 percent in the joint venture company.
Mining News expects that Hunter Dickinson will form a publicly traded juniorto carry out the continued exploration at Delta. The company took a similar approach when it optioned the Niblack project in Southeast Alaska, later forming Heatherdale Resources Ltd. to conduct an aggressive exploration campaign at the VMS deposit.
Like the Niblack project, Brommeland sees Delta as promising precious metals-rich VMS with the potential to become a world-class deposit.
“We are very encouraged by what we have seen. There is opportunity there to establish some continuity in the high-grade resources that the project is known for. There is precious metal enhancement in the system, and we look forward to moving the project forward and building on those resources,” she said.