Big Chunk Super Project
At a glance
|Property rights||Exclusive mineral exploration rights held by wholly-owned Alaskan subsidiary Big Chunk Corp|
|Location||Approximately 200 miles southwest of Anchorage on the north side of Cook Inlet|
|Area||54 State mining claims on 12 square miles (7,680 acres) in 2 blocks|
|Metals sought||Copper, gold, molybdenum (moly), silver and zinc|
About the company
As August, 2012 Liberty Star has commenced exploratory drilling on the BCSP, south block. The phase 1 drilling plan retrieved core from depths extending to 1,696 feet.
Liberty Star’s ground is located near year-round ice-free tidewater on the Pacific Ocean at Cook Inlet. Known mineralization in this area occurs near surface in an area of gentle topography and low elevations. The Pebble Project, a joint venture between Northern Dynasty Minerals and mining industry giant AngloGold seeks to construct and operate an open pit and underground mine in an area considered one of the richest for porphyry gold, copper and molybdenum in the world. Further development of a port on the Cook Inlet, nearby roads, and suitable energy sources are already in process with the approval of the State of Alaska and the Federal Government.
In May 2010 Liberty Star announced that its geophysical contractor (Geotech Ltd.) had confirmed multiple porphyry copper ZTEM geophysical signatures in Big Chunk’s south claim-block. In August 2012 Liberty Star began drilling in the BCSP south block.
2009 ZTEM Surveys
In June 2009 Liberty Star contracted Geotech Ltd. (a Canadian based full service contractor specializing in airborne geophysical surveys) to participate in performing assessment work required by the Alaska Bureau of Mineral Resources for the assessment year 2009/2010 on the Big Chunk Super Project.
At the request of Mr. Briscoe, Geotech Ltd. executed a full ZTEM program over the south block of the Big Chunk claims. ZTEM (Z Axis Tipper Electromagnetic System) is a helicopter borne survey method measuring electromagnetic activity. Geotech’s technology and sensitive measuring equipment enables detection and modeling of the shape of metallic mineral bodies at more than two kilometers (3,300 feet) below the surface. Conducted in August 2009, the survey consisted of 1,256 line km (780 line miles) of ZTEM and very detailed airborne magnetics. The survey lines were spaced 250 meters (825 feet) apart.
In April 2010 Liberty Star received initial word from Geotech that the 1D models resulting from the ZTEM surveys confirmed Mr. Briscoe’s projections for multiple porphyry centers and associated Carlin Style and Round Mountain Style stand-alone gold deposits to be discovered within the Big Chunk caldera.
By May 2010 Geotech had presented the results of computer processing derived from the ZTEM data; the results were a 2D inversion which allows for a three dimensional approximation of the porphyry systems present in the south block of the Big Chunk Super Project.
With the ZTEM data in hand, Mr. Briscoe, Liberty Star’s Chief Geologist, collaborated with other experienced geology specialists to analyze all existing geologic, geochemical, and geophysical data sets compiled from the 2004-2009 exploration work. Commented Mr. Briscoe, “Over the last six years we have carefully gathered across the entire Big Chunk caldera some 11 thousand geochem samples and assayed them for 64 elements each, completed low level high resolution aeromagnetics and compiled base geology. Additionally, we have completed over 140 miles of ground based IP geophysics. All of this data is in digital format and can be compared and interpreted together at the same scale. The new ZTEM data for the Big Chunk Super Project-South Block will be another step in our meticulous exploration process. Along with all the preceding studies, it will be used to refine and pinpoint what these mutually reinforcing data appear to show – anomalies that are characteristic of large porphyry copper mineral bodies, which may contain significant mineralization. Accurately placed drill holes to test these mutually reinforcing data will be the final step in testing for the presence of significant mineralization.”
In May 2010 Liberty Star received word from Geotech Ltd. that their interpretation showed at least 6 to 7 signatures that are consistent with porphyry copper responses. Stated in their report: “Comparison against ZTEM 2D resistivity inversion results have defined resistivity features that resemble typical potassic-altered core and pyritic-propylitic halos over known porphyry systems, extending to great depth ( 2 km or about 6562 feet).”
These anomalies are in the size range of the footprint of the nearby Pebble deposit(s), also within the Big Chunk caldera, and go to significant depth. Also stated in the report “Porphyry coppers… tend to be associated with pronounced resistivity highs associated with a potassium rich altered core, surrounded by resistivity lows associated with pyrite propylitic alteration halos (i.e. Mt Milligan, San Juan-Lone Star, Morrison etc.).” Geotech’s conclusions are consistent with the Porphyry Copper Model, which Company Director Dr. John Guilbert co-developed and is described and illustrated in his book, Geology of Ore Deposits. In June, 2012 Geotech delivered enhance imagery of the ZTEM surveyed area that added a more detailed understanding of the terrain.
2004 – 2005 Exploration Program and Results
Initial staking & aeromag
Liberty Star staked the property in December 2003. An aeromag survey was flown over the property in January through May, 2004. Field work, including surface sampling, Induced Polarization (IP) geophysics, and drilling, was conducted from June through October 2004.
The aeromag survey was flown in January through May 2004 by McPhar Geophysics with the use of a fixed-wing aircraft. The survey covered approximately 1,407 square miles. It was flown at 820 foot line spacing and an optimum elevation of 395 feet; both of these controls lead to a highly detailed survey.
A majority of the 2004 field work was surface sampling. The table below summarizes the number of samples collected during this work. Water samples were collected and analyzed for fluorine in a field lab, for rapid response to fluorine anomalies.
|Sample Type||# of samples|
Thirty days of both dipole-dipole and Reconnaissance IP (RIP) was conducted in August and September 2004. Approximately 26 miles of dipole-dipole was completed and 30 RIP stations were measured, over an area of 13 square miles. A few small areas of IP response were detected with the RIP survey. IP response was measured on all four IP lines at White Sox. These results indicate the presence of disseminated metallic material with consistent readings above 30 msec or mrad.
Four drill holes, totaling 1329 feet, were completed in the White Sox area. Visible copper mineralization was noted in two holes and visible molybdenite was noted in several places in one hole. Low grade gold was also encountered with the other mineral intercepts. This mineralization and the associated alteration may be indicative of a copper porphyry system.
2005 Exploration Program
The Big Chunk property is in various stages of exploration. The White Sox area has received the most work and is a little more advanced than other portions of the property. A mineralized center has been identified with drilling and geophysics there. Additional drilling on and near the IP response is planned. Four months of planned IP should fully delineate the IP response at White Sox with additional IP planned to the north, east and south of the 2004 survey. The company proposes to continue to drill to evaluate those areas where the appropriate IP response is >30 mRad. If ore-grade mineralization is encountered, the company hopes to initiate a grid drilling program to delineate resources, if and as time in the season allows.The company proposes to conduct dipole-dipole and reconnaissance IP on the remainder of the property. Any higher quality geochemical anomalies will be evaluated with dipole-dipole IP. If time in the season permits, the company intends to drill test dipole-dipole IP responses over 40 mRad, if any are detected.The company intends to evaluate lower quality geochemical anomalies with RIP and to detail any RIP anomalies with dipole-dipole IP.
Read about “The Acquisition of Big Chunk“