|Quadrangle map, 1:250,000-scale||LG|
|Quadrangle map, 1:63,360-scale||B-4|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||This is the original Shorty Creek prospect that was drilled in 1972 (Freeman, 2010). Since 2005, it is one of several prospects often referred to as part of the Shorty Creek project which covers a large area and several other prospects. Conversely, in discussing the Shorty Creek project, this prospect is often referred to as the Hill 1710 prospect (e.g., in Freeman, 2010). The prospect is about 4.9 mile south of Livengood on a north-south ridge at the hill 1710 at the headwaters of Shorty Creek and Ranney Hollow 0.4 mile northeast of the center of section 10, T. 7 N., R. 5 W. of the Fairbanks Meridian.|
The rocks in the Shorty Creek area are mainly the Lower Cretaceous Wilber Creek sequence of folded black carbonaceous siltstone, gray feldspathic sandstone and silty sandstone, black shale, and polymictic conglomerate (Albanese, 1983a; Weber and others, 1992). The sequence disconformably overlies Lower Paleozoic carbonate, volcanic, and pelitic rocks. Several small plutons, mostly of granodiorite composition, are in the Shorty Creek area. Biotite hornfels and lesser diopside hornfels is widespread. Although outcrops of the plutonic rocks crop are sparse, the widespread hornfels suggests large intrusions nearby or at depth. The structure of the area is dominated by northwest-directed, northeast-trending thrust faults and northeast-trending, open to recumbent isoclinal folds (Freeman, 2010).
The Shorty Creek prospect is in a strong geochemical soil anomaly marked by the association of silver, arsenic, bismuth, molybdenum, antimony, tungsten, copper, lead, zinc, and tin. This anomaly continues to the northeast for at least 1.4 miles to peak 1890. Operators drilling at the prospect in the 1970s concluded that the mineralization was associated with felsic dikes and sills that intrude the Cretaceous Wilber Creek sequence (Freeman, 2010).Hill 1710 is associated with a curvilinear magnetic high that is offset by the Ranney Hollow fault in an apparent left lateral sense (Abrams, 2015). The cause of this magnetic anomaly may be related to contact metamorphism around a buried intrusive which has undergone magnetite destructive alteration or the anomaly may be from copper-gold magnetite skarn mineralization hosted in Lower Paleozoic carbonate units dipping to the south beneath the Wilber Creek sequence.
|Geologic map unit||(-148.547300900774, 65.4511642966515)|
|Mineral deposit model||Copper-molybdenum porphyry system (Cox and Singer, 1986; model 21a).|
|Mineral deposit model number||21a|
|Age of mineralization||Probably related to intermediate plutons, one of which has been dated at 63 Ma (Albanese, 1983a).|
|Alteration of deposit||Alteration observed is biotite to lesser diopside hornfels related to contact metamorphism from the intrusion of several plutons (Freeman, 2010).|
|Workings or exploration||
The Shorty Creek prospect was first staked for antimony in 1972 (Freeman, 2010). Some additional sampling soon led to the concept that it was a copper-molybdenum deposit in a large aeromagnetic anomaly. Earth Resources Inc. staked the property and drilled 10 holes in 1972 on the south slope of Hill 1710, possibly in a joint venture with BP Minerals. Eakins (1974) collected four grab samples from drill cuttings left at the Earth Resources drill pads. The samples contained 170 to 1,050 parts per million (ppm) copper, 20 to 60 ppm lead, 105 to 640 ppm zinc, less than 0.2 to 1.1 ppm silver, and less than 100 parts per billion (ppb) gold.
There has been no further drilling on this Shorty Creek prospect. However, there is a long history of geologic mapping, geochemical sampling, aerial and ground geophysical surveys by industry and government, including drilling at one nearby prospect (Freeman, 2010). After the discovery of mineralization in 1979 along the Alyeska Pipeline service road about 2.5 miles south of the Hill 1710 prospect (Robinson and Metz, 1979), there was considerable interest and drilling at the Hill 1835 prospect (LG209) about 1.7 miles southeast of the Hill 1710 prospect. The area was largely dormant from 1990 to 2005.
In 2005, Select Resources leased a large block of claims, staked more, and in 2010 they held several large blocks that totaled more than 300 claims and included several other prospects (Freeman, 2010). In 2005, they did considerable rock and soil sampling on their claims which they collectively call the Shorty Creek project or just Shorty Creek.
Freegold Ventures Limited (Freegold) completed 28.6 kilometers of induced polarization (IP) surveying and collected 354 soil samples in 2014 covering the prospect areas of Hill 1710 and Hill 1835 (LG209). Soil samples with anomalous copper and molybdenum were associated with lower chargeabilities over Hill 1710 (Abrams, 2015).Freegold Ventures Limited’s 2016 drilling program at their intrusion-related Shorty Creek property included 7 holes totaling 3,038 m; 2 holes were drilled in the 'Hill 1835' area, and 5 holes were drilled in the '1710' area to test copper-molybdenum targets. ‘Hill 1835’ mineralization is spatially associated with a magnetic high defined by airborne- (Burns and others, 2015) and ground-based surveys, as well as magnetic highs in inverted profiles. Drilling highlights include 434.5 meters averaging 0.57 percent copper-equivalent, and 409.6 meters averaging 0.41 percent copper-equivalent. In the ‘1710’ area, 5 drill holes totaling 2,019.8 m, tested a copper-molybdenum soil anomaly and magnetic high. Drill hole SC 16-07 intersected 0.11 percent copper and 0.011 percent molybdenum from 0-159 m, including 0.15 percent copper and 0.009 percent molybdenum from 0-70.8 meters within quartz-feldspar porphyry. The entire 396-meter-long drill hole averaged 0.08 percent copper and 0.006 percent molybdenum. Additionally, Freegold conducted new ground-based geochemical sampling, geophysical surveys, and claim staking in 2016, and identified the new Quarry and Steel Creek target areas (Athey and Werdon, 2017).
|Indication of production||None|
Additional commentsThe new Steel Creek geophysically defined target does not correspond to ARDF description LG027 (Steel Creek).
|Reporters||D.J. Grybeck (Contractor, USGS); N.V. King (Alaska Earth Sciences); M.B. Werdon (DGGS)|
|Last report date||8/26/2017|