Star Lake

Targets: Carlin-style gold deposits along a structural and geophysical extension of the Carlin trend
Area: ~7380 acres, or ~30 km2
Location: Northern extension of Carlin Trend, northern Nevada, USA
Ownership: 100%

Overview – An Extension of the Carlin Trend

Star Lake consists of 369 unpatented mining claims in northwestern Elko County and northeastern Humboldt County, 145 kilometers northwest of Elko, Nevada. It is an early stage project targeting a district scale extension of the Carlin Gold Trend. The Carlin Trend is one of the world's major gold provinces with more than 80 Moz of gold production and reserves.
Location of the Star Lake project along the projection of the Carlin Trend
Location of the Star Lake project along the projection of the Carlin Trend.
Digital Elevation Model showing gold deposits and mines with crossed shovel symbol. Dashed lines show projections of major gold trends.

Overview – An Exploration Frontier with Carlin geochemistry

In 2006 a USGS evaluation of surficial geochemistry in the northern Great Basin identified numerous principal component factor anomalies related to a suite of elements associated with hydrothermal mineralization. Many of these anomalies are present in major mining districts in northern Nevada, including the Carlin Trend and other gold trends. The USGS concluded that anomalies not associated with known districts "...can be reasonably viewed as exploration frontiers where the probability of discovery of new deposits may be high" Star Lake is one of these anomalies.
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Residual principal component factor geochemical anomalies associated with hydrothermal mineralization.
USGS geochemistry data from Ludington, et. al, 2006, Economic Geology, v. 101, no. 1.

Overview – Gravity Signature similar to North Area of the Carlin Trend

Not only is the project on strike of the Carlin Trend, but a 2007 survey showed that there is a large positive gravity anomaly coincident with the geochemical anomaly. The gravity anomaly indicates the presence of an uplifted horst block of Paleozoic rocks and bears remarkable similarity to the signature of the horst block underlying North Area on the Carlin Trend. Here, major ore bodies such as Post and Meikle are present on the horst margin proximal to the block-bounding structures.
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Star Lake residual complete Bouguer gravity anomaly, showing interpreted structures.
Red lines denote property location. Structures shown as black dashed lines.
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Carlin Trend North Area residual gravity, structures and ore bodies.
Ore body shapes shown in solid red. Structures shown as black dashed lines.

Geology – Stratigraphy and Hydrothermal Alteration

Rocks exposed at surface consist of Miocene tholeitic basalts, cinder cones and sedimentary interbeds. Drilling penetrated approximately 35 to 100 meters of this unit. Underlying the basalts, drilling penetrated approximately 180 to 440 meters of older Tertiary latite to dacite porphyry lavas. Beneath this, there is a rhyolite flow dome of unknown thickness. Drilling has locally intersected a hydrothermal system characterized by quartz veining, argillization and brecciation, with anomalous gold values up to 0.101 g/t.
Soil sampling at Star Lake
Star Lake project surface exposures.

Geology – Structure

A pronounced topographic linear present on the regional and district-scale digital elevation models reflects the northwest-trending fabric of the Carlin Trend. Prominent northeast-striking structures are evident in the gravity data. Some may be a conjugate set to the northwesterly trend. However many are parallel to the northeast trend of the Getchell lineament, which trends into the project area from the southwest. This trend also carries gold mineralization and adds a structural intersection to the target area.
Location of the Star Lake project along the projection of the Carlin Trend
Regional Digital Elevation Model showing major north-central Nevada gold trends.
Digital Elevation Model showing gold deposits and mines with crossed shovel symbol. Dashed lines show projections of major gold trends.
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District-scale Digital Elevation Model showing Star Lake Lineament.
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Star Lake complete Bouguer residual anomaly with interpreted structures.
Red lines denote property location. Structures shown as black dashed lines.

Drilling –First pass test, four widely-spaced holes

Altan Nevada conducted initial drilling in 2009 with four widely-spaced core holes (340 m -770 m) testing structural targets along a reconnaissance MT/CSAMT line. The holes bottomed in Tertiary volcanic rocks, with three ending in a large flow dome. Anomalous gold was locally present. This drilling tested one concept in a limited part of the project. Altan Nevada management will use the results of these holes to further develop targets for future drilling.
2008 reconnaissance MT/CSAMT geophysical plot
2008 reconnaissance MT/CSAMT geophysical plot.

Targets – Untested Carlin-type gold potential

Given the similarity of geochemical and geophysical anomalies to features associated with major ore bodies on the Carlin Trend, Carlin-type gold deposits represent the most compelling target at Star Lake. The 2009 drilling program intersected a rhyolite flow dome in three of the four holes. Data compilation from the drilling indicates that target Carlin Trend host rocks could be present on the margins of the flow dome at depths below 350 meters.
Geologic cross-section of the Star Lake project illustrating target concept
Geologic cross-section of the Star Lake project illustrating target concept.
Flat-lying reddish and greenish units are Tertiary basaltic and intermediate volcanic flows. Thick pink unit is a rhyolite flow dome. Blue unit at right represents possible position of Paleozoic Carlin host strata.

Recent Work – Airborne magnetic survey indicates deep-rooted structure

Altan Nevada completed a 208 line-kilometer airborne magnetic survey in 2012. Primary survey lines were oriented east-west and spaced at 500 meter intervals Regional processing of the data emphasized deeper features relative to shallower ones. A major feature trending slightly east of north extends across the magnetic data. This feature separates two magnetic domains with higher values to the east and lower values to the west. The line of separation is abrupt and likely reflects a structure.
Map showing location of 2012 Star Lake airborne magnetic survey
Map showing location of 2012 Star Lake airborne magnetic survey.
Yellow polygon denotes survey location.
Reduced-to-pole regional magnetic data and interpreted structures
Reduced-to-pole regional magnetic data and interpreted structures.
Heavy dashed blue line is interpreted major deep-rooted NNE-striking structure.

What’s Next – SRK recommends further target definition and drilling

According to SRK Consulting: “The Star Lake Gold Exploration Project remains an exciting exploration play in that if the above concepts are indeed confirmed with drilling, that success will have defined a district-scale extension to the Carlin Trend.” SRK recommends a re-interpretation of the geophysical and geochemical surveys in light of the first 4 drill holes to refine interpreted bedrock structures and define other drill targets in the large area under claim.
Plot of Enzyme Leach soil arsenic geochemical anomalies and gravity showing presence of untested target potential north of 2009 drilling area
Plot of Enzyme Leach soil arsenic geochemical anomalies and gravity showing presence of untested target potential north of 2009 drilling area.
Dashed black lines are structures interpreted from gravity.


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