Empire Creek
Empire Creek Exploration
Empire Creek Geology
Republic Graben
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Empire Creek Project
Overview |
Exploration |
District Geology |
Republic Graben
Empire Creek has the potential to host a substantial gold deposit similar to others in northeast Washington, including the geologically-similar Overlook and Buckhorn deposits.
Project Overview
The Empire Creek Project consists of 34 unpatented claims on the western edge of the Republic Graben, twelve miles north of Republic, Washington. The Tertiary grabens of northeastern Washington contain some of the highest-grade, bulk-tonnage gold deposits in the United States.
The primary objective at Empire Creek is the discovery of gold-bearing massive sulphide deposits in Permo-Triassic age host rocks. Consulting geologists believe that Empire Creek may contain high-grade gold skarns similar to those found at the nearby Overlook and Buckhorn deposits. Empire Creek bears many similarities to the 1.6-million ounce Buckhorn Deposit including graben margin location, alteration-type host rock, laterally-extensive magnetic highs, and local high-grade gold.
Recently completed drilling tested an intense ground magnetic anomaly roughly 3000 feet long and 1000 feet wide.
Exploration
Kimberly completed its initial reverse-circulation drilling program at Empire Creek. The program consisted of five holes totaling 2,410 feet, targeting intense magnetic anomalies found in Greenstones with associated high threshold gold-silver soils and rocks. Preliminary results indicate the presence of epidote-quartz-calcite veining along with zones of anomalous magnetite and sulfide.
Both an IP-Resistivity survey and at least two ground magnetic surveys have been completed at Empire Creek. The IP-Resistivity survey was inconclusive, but the ground magnetic survey completed by Kennecott in 1995 confirmed the results of an aeromagnetic survey undertaken by the State of Washington in 1960. The magnetic surveys have revealed an intense ground magnetic high covers an area of over 1,000 feet in width and 3,000 feet in length.
The geophysical similarities between Empire Creek and the productive mines of the district are noteworthy. The ground magnetic anomaly compares favorably in size and intensity to others that overlie regional gold skarn systems, particularly the one seen at Overlook Deposit. A visual comparison suggests that the Empire Creek anomaly represents a deep-buried gold skarn, which is shallower, longer, and of comparable width to Overlook.
In the present area of interest, detailed mapping and complimentary geophysical and geochemical surveys completed in the 1980s and 1990s by U.S. Borax and Kennecott did not result in tangible drill targets. However, as more information has emerged with the development of the Overlook and Buckhorn Deposits, so have obvious similarities between the geology of Empire Creek and other local skarn/replacement occurrences that were not previously known.
District Geology
Permo-Triassic age rocks of the Anarchist Series host spotty, high-grade gold mineralization in the vicinity of Empire Creek. These metasediments have been altered, commonly appearing as hornfels and pyroxene skarn. Host rocks in the previously drilled areas consist primarily of silicified and hornfelsed clastics of Permo-Triassic age. The field term 'greenstone' has also been used to describe these rocks.
Structurally, the property lies on the western edge of the Republic Graben. The host sediments exist either as the upper plate of a thrust fault or as a roof pendant within a granitic cupola. The Lambert Creek Thrust Fault is spatially associated with the nearby Overlook, Key East and Key West deposits.
Drilling by Crown Resources has shown that skarn mineralization at the Buckhorn Deposit grades laterally into hornfelsed clastics at the Crystal Butte property, two miles to the south. A possible analogy exists at Empire Creek. Hornfelsed clastics, shown to host erratic, high-grade gold in drilling just over one mile to the north, could grade laterally into a gold skarn concealed at depth beneath the ground magnetic high at Empire Creek.
Republic Graben
The mines of the Republic Graben have reportedly accounted for five million ounces of gold production since the first claims were staked in 1896, most notably from the Knob Hill Mine which operated for nearly a century before being closed by Hecla in 1995.
More recently, Echo Bay (now Kinross) has mined a series of modest-sized VMS and epithermal gold deposits, providing ore to a centralized mill at Kettle River. Since 1989, the Kettle, Overlook, Key East, Key West, Lamefoot, and K-2 deposits contributed to gold production that exceeded 100,000 ounces through the late-1990s before declining sharply over the last few years. Ore grades, recovery rates, and cash costs have remained relatively stable at roughly 0.20 ounces per ton (oz/t) gold, 84 percent, and $230 per ounce, respectively, during that time.
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