|Quadrangle map, 1:250,000-scale||BT|
|Quadrangle map, 1:63,360-scale||A-1|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||The prospect is about 8 to12 miles up the No Name Creek valley from its confluence with the Ray River. Site for this record is the confluence of the south fork of No Name Creek and a small, unnamed tributary from the north. Accuracy of the location is less than 1,000 feet. The prospect area extends into the Beaver Quadrangle. The prospect area is accessible from the Dalton Highway, which crosses the creek about three miles downstream of the site. This placer prospect is on, and potentially includes much of the lower No Name Creek valley, although the creek is infilled with loess and vegetation and drilling would be required. Mineralized exposures at the site are limited to hand trenches that expose a series of bench channels to both the north and south of the present drainage (Barker, 1991a,b), located in the NW¼, NE ¼ Section 22 and the SW ¼ of the SE ¼ Section 15, T. 15 N., R. 12 W., of the Fairbanks Meridian.|
The No Name Creek drainage, including its southern fork with headwaters in the Ft. Hamlin Hills pluton, flows southwesterly approximately 20 miles, ultimately joining the Ray River at the point where the Ray bends south to join the Yukon River. Much of the No Name Creek drainage downstream of the Dalton Highway is incised into, or has cut through, Miocene-age basalt flows (Albanese, 1987; Barker, 1991a, b) that overlay Tertiary (?) white gravel (Barker, 1991b). At least low grade placer tin, rare earth elements (REE), and gold occur in all heavy mineral samples collected from poorly exposed cutbanks downstream of the Dalton Highway (Barker, 1983, 1991a). At the site, however, remnant channel exposures on several low bench features contain up to six pounds of tin per cubic yard (3,580g/m3) plus significant REE mineral concentrate. Gold is noted in all samples from lower No Name but is absent in the bench channels upstream at the site (Barker, 1991a).
The Fort Hamlin Hills pluton is considered part of the broad northeast-trending peraluminous Ruby Batholith of central Alaska (Chapman and others, 1982; Patton and Miller,1970, 1973; Barker and Foley; 1986; Herreid, 1969). Generally the granitic rocks are coarse-grained, equigranular to porphyritic, orthoclase-biotite-quartz monzonite varying to granite with subordinate phases of aplite, biotite aplite, tourmaline aplite, and fine-grained quartz monzonite. Tourmaline pegmatite phases have been recognized locally. The granitic rocks cut Paleozoic schist, phyllite, quartzite, and lesser greenstone and limestone. The granitic plutons feature alteration zones including chloritic and hematic greisen veins/bodies that are the apparent source of at least some of the detrital cassiterite and REE minerals. Mineralogical examination of heavy mineral concentrates from the remnant bench channels confirmed abundant cassiterite and an anomalously high percentage of xenotime relative to monazite (Mariano, A., mineralogist, 2012, personal communication).
The heavy mineral concentration is enhanced by multiple stages of fluvial downcutting of the No Name Creek drainage which has repeatedly re-concentrated earlier sediments. The result of this channel down- cutting/reworking/re-deposition at continually lower elevations is a highly concentrated heavy mineral fraction. Remnants of former alluvial terrace deposits occur high on the west and north slopes of the Fort Hamlin Hills and are found to mantle the basalt flows on lower No Name (Albanese, 1987, Barker, 1991b). Each repeated downcutting event removes and transports more of the lighter aggregate downstream, thus potentially upgrading the residual heavy mineral concentrations. Upgrading of the heavy mineral fraction in the alluvial deposits is well exemplified by the series of bench channels on east fork of No Name Creek where the highest grades are in the lowest elevation bench channels.Remnant (late Tertiary?) terraces as high as 100 meters (320 feet) along the left limit of No Name near the Dalton Highway are evidence of ancient alluvial gravel deposition and though mineralized they contain less REE and tin in heavy mineral fractions than the present creek bed. These high-level channels of ancient No Name Creek have been developed for construction aggregate used along the Trans Alaska Pipeline (Barker, 1991a).
|Geologic map unit||(, )|
|Mineral deposit model||Placer tin (Cox and Singer, 1986; model 39e).|
|Mineral deposit model number||39e|
|Age of mineralization||The Ruby batholith region is within the glacial ice-free Quaternary province of Beringia, defined as the non-glaciated intermontane region extending from eastern Siberia and eastward across a then-dry Bering Sea floor, thence transecting interior Alaska, and extending into northwestern Canada. Across the Beringia region, the fluvial processes have generally continued since the Tertiary and consequently the region is historically known for the Pleistocene mammals that survived there, as well as a multitude of placer gold camps and districts such as the Klondike. In the Ruby batholith region, the on-going erosional and mineral concentration processes that concentrated valuable heavy minerals have apparently remained uninterrupted since the late Tertiary.|
|Alteration of deposit||Thermal alteration from the batholith is widespread and silicification extends well into the Paleozoic host rocks. Locally extensive, tourmalization, potassic, carbonate, and argillic styles of advanced alteration can be mapped and generally are associated with regional-scale faulting. Such zones of altered and weakened rock give rise to locally intense large-scale disintegration of the bedrock granite, which has released the contained heavy minerals. Source of the placer tin- and REE- minerals appears to be widespread argillic alteration and greisen vein-like occurrences locally overprinted with chloritic and/or hematic alteration (Herreid, 1969; Barker and Foley, 1986). Greisen samples will generally contain 100 ppm to as much as 2500 ppm Sn and elevated REE. Cassiterite has also been found associated with quartz veins at a few locations in the batholith. The older fluvial deposits as represented by the remnant channels on No Name Creek also exhibit a degree of residual (in-place) concentration that are characterized by feldspar grains altered variably to white and brown clayey quartz-rich sediments that are locally seen to grade upward into unaltered cross-bedded fluvial gravel.|
|Workings or exploration||The No Name Creek prospect has been explored by the U.S. Bureau of Mines as part of the Critical and Strategic Minerals Program in the 1970s-1980s (Barker, 1983, 1991a,b; Barker and Foley, 1986). Gravel samples have been collected and processed from numerous locations along the creek and from the remnant bench channels at the site. All samples were processed by gravity methods for the analysis of the heavy mineral content (Barker, 1991a). Ucore Rare Metals, Inc. acquired the No Name Creek claim block in 2011 and in 2012 announced additional sample results for heavy mineral concentrates from the bench channels (see data table http://ucore.com/projects/ray-mountains-alaska and (Ucore.com, Ucore Confirms Widespread Rare Earth Mineralogy in Central Alaska, January 16, 2012).|
|Indication of production||None|
|Reserve estimates||A ‘very preliminary’ estimate of the tin resource potential for the combined Ray River and No Name Creek drainages was made by the U.S. Bureau of Mines ‘for the purpose of land-use management and planning purposes.’ A total of 62 to as much as 172 million pounds-tin in 300 million cubic yards of gravel was estimated to be present (Barker, 1991a). Grade is estimated between 0.2 and 0.5 pounds-tin per cubic yard; highest grade values are mostly from upper No Name Creek. No estimate was made for the REE, gold, or other possible placer minerals.|
Additional commentsNo Name Creek flows through lands on which the State of Alaska has filed ‘Priority Selection’ under the land entitlement provision of the 1959 Statehood Act. Various temporary land withdrawals remain to be lifted by the Bureau of Land Management (BLM) before these selections can be processed. The BLM will not issue any permits for surface disturbance activities including exploration under these withdrawals or State Selection status.
|Last report date||3/15/2016|