The East Spruce project explores potential Carlin-style sediment-hosted gold mineralization in the eastern part of Spruce Mountain mining district. The project area is on trend to the southwest from Newmont's recently discovered Long Canyon gold deposit. The project consists of 69 claims 100% owned by Miranda.
The Long Canyon trend, is emerging as a new gold trend in northeast Nevada, and the East Spruce project is well positioned within it. Regional aeromagnetic data suggest that the project lies on the east margin of an interpreted large buried intrusion that is part of a northeast alignment of intrusive rocks that extends about 130 mi (220 km) from the gold-bearing Bald Mountain mining district in the southwest, through East Spruce, Long Canyon, and further northeast to the Tecoma (gold) mining district (Fig. 1).
Regional reconnaissance during 2009/2010 in the East Spruce project area revealed an area of elevated rock-chip gold, silver, and arsenic along 2,000 ft (610 m) of a north-northwest-trending fault zone. The elevated gold occurs in silicified and decalcified limestones along the fault. Gold mineralization in the fault zone is interpreted as upward leakage from an underlying gold system.
The East Spruce project covers 2 sq mi (5.2 sq km) in 69 unpatented mining claims on the east flank of Spruce Mountain Ridge 37 miles (63 km) southeast of Wells, Elko County, Nevada. The project is 28 mi (47 km) southwest of the Long Canyon gold deposit (Fig. 1). Access to the property is via gravel and dirt roads starting about 10 mi south of Wells. Relief at the property ranges from 6,400 to 7,600 ft (1,950 to 2,320 m) and dominant vegetation is juniper and pinion pine.
The geologic setting at the East Spruce project is similar to other Nevada Carlin-style sediment-hosted gold systems (e.g., Goldstrike, Pipeline, Cortez Hills, Star Pointer) where gold mineralization is in folded carbonate strata adjacent to variably mineralized intrusive systems. On the East Spruce property and adjacent areas folded and faulted Upper Paleozoic limestones are intruded by Cretaceous/Tertiary granitic stocks and porphyritic dikes (Fig. 2). The exposed carbonate units are the Pennsylvanian Riepe Spring Limestone and successively overlying Lower Permian Rib Hill and Pequop Formations. These units form a north-northeast-trending dome at least 3 mi (5 km) long by 1.5 mi (2.4 km) wide. Thin rhyolite porphyry dikes and faults trending northwest, north-northwest, and northeast cut the carbonate units.
Anomalous gold (>50 ppb Au) in rock chips is closely associated with the structures. Gold-bearing replacement silicification occurs along faults proximal to the axis of the dome and as irregularly distributed localized zones in the area of the fold. At the north end of the property, seven of nine rock samples contain gold values from 0.148 to 0.548 g Au/t (0.004 to 0.016 oz Au/ton) along 2000 ft (610 m) of a silicified and decalcified north-northwest-trending fault zone that cuts the lower Pequop Formation (Fig. 3). These samples are also anomalous in pathfinder elements with maximum values of 3.85 ppm Ag, 1,100 ppm As, 25.6 ppm Sb, and 0.58 ppm Hg. This silicified fault zone is mappable for 3,200 ft (975 m) and projects under the pediment cover to the south-southeast.
Historically, the base and precious metal mineralization of the Spruce Mountain mining district attracted numerous explorers, even to the extent of establishing the historic town site of Sprucemont in the 1870's, about four miles west of the project area. Revived exploration interest by companies including Newmont, Freeport, and AMAX from the 1950's to the early 1980's evolved from the porphyry copper-molybdenum occurrences in the district. Across the Spruce Mountain Mining District, the presence of widespread, but variably distributed precious and base metals, favorable sedimentary host rocks, granitic porphyry intrusions, and variably altered and mineralized structures attract continued exploration interest.
At the East Spruce property, overgrown shallow prospect pits, trenches, and reclaimed drill pads give evidence of historic exploration efforts. Only minor drilling, probably by Echo Bay (BLM records) and some smaller companies, is indicated from the few existing reclaimed drill pads. No information is currently available for the results of past exploration or drilling on the property.
Miranda's entry into the East Spruce project area resulted from stream sediment and rock chip anomalies developed by Miranda geologists in a regional generative exploration program during 2009 and 2010.
The principal exploration target at the East Spruce project is sediment-hosted gold mineralization associated with the north-northwest trending fault zone near the northern part of the property. The fault cuts the eastern limb of a north-northeast-trending dome at least three miles long in the Upper Paleozoic platform carbonate section. Miranda believes alteration and mineralization along the fault represent upward leakage from underlying Carlin-type gold mineralization. The fault zone displays silicified, decalcified, and hematite stained rock for its exposed 3,200 ft (975 m) length. Rock chip samples from its northern 2,000 feet (600 m) are anomalous in gold up to 0.548 g Au/t (0.016 oz Au/ton) and the Carlin-type pathfinder elements (Ag, As, Sb, Hg). The southern end of the altered and mineralized fault projects onto gravel-covered pediment.
Other localized zones of gold-bearing silicified limestone occur within about 2,000 ft (600 m) of the long axis of the dome.
Miranda's Business Model
Miranda Gold Corp. is a gold prospect generator. In keeping with its business model, Miranda will seek a joint venture partner for the East Spruce project