AndreaBozzo/ceres-open-data-index huggingface dataset:
Stratigraphy, geochemistry and source rock potential of the Boundary Creek Formation, North Slope, Yukon and a description of its burning shale locality

The Cenomanian-Turonian (Upper Cretaceous) Boundary Creek Formation is a mudstone, shale and silty shale unit that is exposed in river and creek cuts on Yukon’s North Slope. As part of the CASE-15 expedition, co-led by the Yukon Geological Survey and the German Federal Institute for Geosciences and Natural Resources, fieldwork in July 2013 involved measuring and sampling Boundary Creek Formation strata in two locations, and investigating a burning shale exposure near the confluence of Boundary Creek and the Big Fish River. Shale and mudstone samples were analyzed for XRF lithogeochemistry and organic matter quantity, along with thermal maturity and type using RockEval/TOC and vitrinite reflectance techniques. The Boundary Creek Formation is interpreted to have been deposited by turbidity currents moving through an outer shelf to slope environment in the distal part of the foreland basin, outboard of the Cordilleran orogeny. Lithogeochemical data suggest that at times throughout the deposition of Boundary Creek Formation shale, ocean water may have been depleted in oxygen, resulting in anoxic conditions that would have been favourable for organic matter preservation. Analyses of surface samples suggest that some areas have poor to no petroleum potential and are thermally overmature with respect to oil generation. In others, good to very good petroleum potential exists and the shale is oil to oil and gas prone and thermally mature with respect to oil generation. In these latter areas, specifically in the vicinity of the type section on Boundary Creek, the shale has the necessary components for spontaneous combustion: pyrite, organic matter and a fresh supply of oxygen provided by a landslide. Although burning shale is not unknown in northern Canada, the outcrop of burning shale on Yukon’s North Slope is the first observed in shale of the Upper Cretaceous Boundary Creek Formation.

Organization: Government of Yukon | Gouvernement du Yukon
Placer deposits: Their formation, evaluation, and exploitation, Yukon

The formation of placer deposits has several prerequisites. They include a source for the gold, a mechanism to concentrate it, and time for the concentrating mechanism to work. The source of the gold could be gold-quartz veins, gold-bearing sulphide deposits, or previously formed placer deposits.

Concentration of gold in placer deposits occurs through erosion. Concentrations may occur in residual eluvial and deluvial deposits overlying and close to a lode gold source. Most placer deposits have, however, been further concentrated through the action of moving water in streams or on beaches.

Typical sites for accumulation of placer gold deposits occur where the rate of flow decreases. Such sites include the inside of meander curves, at decreases in stream gradients, at the confluence of creeks, and where physical obstructions such as irregularities in the bedrock surface, or the surface of the sand and gravel occur. In deposits of meandering streams, gold occurs in distinct pay-streaks at the base of the deposits. In deposits of braided streams, however, the gold occurs erratically throughout the deposits.

A variety of sampling methods and other techniques can be used to explore and evaluate placer deposits. Black and white aerial photographs and infra-red photographs are used to identify areas of interest. Geological mapping of placer deposits is done to establish the distribution of the horizons bearing valuable minerals and identify potential impediments to mining.

Bulk samples are taken to determine the valuable mineral content of the deposits. Both small-scale panning and large-scale mechanical excavation are used to obtain bulk samples.

Organization: Government of Yukon | Gouvernement du Yukon
Surficial geology of Apex Mountain (115J/08), Yukon

The Apex Mountain map area is located in the central part of the Dawson Range. Apex Mountain is the highest summit reaching an elevation of 2000 m. Upland topography changes from rounded summits throughout much of the southern half of the map area to more rugged terrain in the north part of the map area where the Dawson Range divide is located. Most of the map area is drained by the Klotassin River and Somme Creek. A cluster of streams near Apex Mountain drain northward into the Selwyn River or Hayes Creek.

Organization: Government of Yukon | Gouvernement du Yukon
Element distribution in Yukon gold-silver deposits

One third of the gold and gold-silver deposits in Yukon were examined and sampled in 1980 to establish a framework of geology and rock chemistry from which variations within and between deposits could be detected and evaluated. Lithologic units within the samples were analyzed for Au, Ag, B, Mn, Cu, Zn, As, Se, Tl, Pb, Bi, Sb, Te, W, Hg, Mo and Cd - elements commonly associated with precious metal deposits. A problem which prevented systematic sampling of many deposits is the lack of underground access and the locally intense oxidation of vein outcrops.

Three aspects of the rock geochemistry are discussed:: 1) different levels of element concentration in the deposits and implications regarding pathfinder elements; 2) distribution of elements in deposit types; and 3) element distribution in specific deposits.

The geology of the deposits is summarized from published works and interpreted in light of recent theories on gold deposits. This report emphasizes common features of the deposits and several genetic models.

Organization: Government of Yukon | Gouvernement du Yukon
Cenozoic syntectonic sedimentation and strike-slip basin development along the Denali fault system, Yukon Territory

This is a multidisciplinary study which combines sedimentology and sedimentary petrology, palynology, organic petrology and structural analysis of the middle Cenozoic Amphitheatre Formation in the St. Elias Mountains, and documents syntectonic deposition in strike-slip basins along the Denali fault system. The outcrops of the Amphitheatre Formation can be divided into two discrete basins:: the northern Burwash basin and the southern Bates Lake basin.

Sedimentological analysis of the Burwash basin identified fault-controlled depocentres which allowed the development of several different types of non-marine depositional environments in close proximity. Palynology and organic petrology data indicate that the Amphitheatre Formation is diachronous and spans the Eocene-Oligocene boundary.

Light-mineral provenance studies of sandstones, clast-counts in conglomerates and paleocurrent analyses suggest that the Wrangellia and Yukon Crystalline Terranes were sources for the Amphitheatre Formation in the Burwash basin. In contrast, preliminary work suggests that Wrangellia and possibly the Gravina-Nutzotin Terrane may have been important sources for the Amphitheatre Formation in the Bates Lake basin.

Structural data combined with geologic mapping indicate a predominance of strike-slip deformation during and after deposition of the Amphitheatre Formation in the Burwash basin. The presence of syndepositional faults with subhoriziontal slickenside indicates that strike-slip deformation occurred during deposition of the Amphitheatre sediments. The Burwash basin contains structures indicative of both contractional and strike-slip deformation, whereas the Bates Lake basin contains structures indicative of both extensional and strike-slip deformation. The change in structural style between the two basins suggests that the Amphitheatre Formation may have been deposited in transpressional as well as transtensional tectonic settings along individual segments of the Denali fault system during the middle Cenozoic.

Organization: Government of Yukon | Gouvernement du Yukon
Investigating a Triassic overlap assemblage in Yukon: On-going field studies and preliminary detrital-zircon age data.

New field and detrital-zircon age data from the Selwyn basin indicate the Yukon-Tanana terrane (YTT) was a source region for Triassic sediments (Smithian Norian; conodont ages) that were deposited along the ancestral margin of North America (NAM). Triassic rocks of the NAM contain middle to late Paleozoic detrital-zircon and geochemical signatures which are unique to the YTT and absent from the NAM, demonstrating that the Triassic rocks represent the earliest observed overlap assemblage linking allochthonous terranes to the NAM in the northern Cordillera. New provenance data also defines and characterizes Jurassic assemblages. Terrane accretion in the northern Cordillera was previously thought to have commenced in Early to Middle Jurassic time; however, the presence of a 40-50 m.y. older Triassic overlap assemblage requires that Triassic rocks were deposited in a collision-related foreland basin setting rather than a stable continental terrace and rise.

Organization: Government of Yukon | Gouvernement du Yukon
Gold in skarns of the Whitehorse Copper Belt southern Yukon

Skarns in the Whitehorse Copper Belt occur in both dolomitic and calcareous carbonate rocks near contacts with the diorite contact phase of the Whitehorse Batholith. The skarns are mineralogically and compositionally similar to typical copper skarns.

The bulk of sulphide mineralization is associated with retrograde alteration. Chalcopyrite and pyrite are preferentially associated with actinolite and chlorite, whereas bornite and chalcocite are preferentially associated with epidote and locally serpentine. The other important copper mineral, valleriite, is restricted to magnesian rocks and is commonly associated with phlogopite, serpentine, and chlorite. Overall, the Whitehorse system is copper-rich and sulphur-poor; iron sulphide minerals are not abundant.

Significant amounts of gold and silver have been recovered from the Whitehorse skarns. Cu, Ag, and Au metal raiots of spot sample assays can be used to discriminate among the different Whitehorse skarns. Deposits formed from relatively pure limestone appear to have low precious metal ratios. Deposits formed from more magnesian protoliths appear to be silver-rich. Deposits with the highest gold ratios appear to have formed from mixed limestone-dolostone lithology.

Organization: Government of Yukon | Gouvernement du Yukon
Assisted revegetation of fine-grained tailings at Whitehorse Copper Mine: A pilot project, 1994-1996

Whitehorse Copper Mine, within the city limits of Whitehorse, produced about 10 million tons of fine-grained calc-silicate tailings before its closure in 1982. The tailings, now desiccated, do not support plants although some areas have been undisturbed for more than 20 years. Barren tailings have high pH and electrical conductivity (E.C.) but are otherwise non-toxic.

The minimum requirements for sustainable plant growth are under study in a pilot project in which freely available compost from various sources was mixed with the uppermost tailings as a proto-soil. Six plots were initially treated with one dose of chemical fertilizer, regularly irrigated and protected from wind. Planted Yukon native grasses germinated and both transplanted trees and seeds in the compost survived. Grass growth was measured after 2 growing seasons and is directly related to the quantity and quality of the compost tilled into the upper 10 centimetres of the tailings. Soil texture, moisture retention and organic nutrients improved. Similar abandoned sites could benefit from the addition of readily available compost and the use of locally propagated seeds and native plants.

Organization: Government of Yukon | Gouvernement du Yukon
Anatomy of a late Jurassic Gilbert-type delta in basal strata of the Tantalus Formation, Whitehorse Trough, Yukon

Most chert-pebble conglomerate units within the Late Jurassic to mid-Cretaceous Tantalus Formation were deposited in shallow, deep and meandering gravel-bed rivers. However, the presence of largescale angle of repose foresets of large- to small-pebble conglomerate, with distinct down-slope termination in laminated mudrocks, indicates that at least some >5 m foresets were formed by episodic flood-controlled progradation of a small river-dominated lobate delta. Architectural analysis of exposures at the Whitehorse Coal deposit, 26 km south-southwest of Whitehorse, indicates periodic rapid progradation into a small lake that was at least 6 m deep. Thinning and downlap of some foreset units indicate shifting location of topset distributary channels. Down-slope transition of gravel foresets into thin sub-horizontal beds of massive and graded sandstone and pebbly sandstone suggests that the foresets were inertia-dominated. Deformation of bottomset beds is directly related to foreset progradation over under-compacted lacustrine clays.

Organization: Government of Yukon | Gouvernement du Yukon
Retrogressive thaw slump susceptibility in the northern hemisphere permafrost region

Mean annual temperatures in the Arctic and subarctic have increased in recent decades, increasing the number of permafrost hazards. Retrogressive thaw slumps (RTSs), triggered by the thawing of ground ice in permafrost soil, have become more common in the Arctic. Many studies report an increase in RTS activity on a local or regional scale. In this study, the primary goals are to: (i) examine the spatial patterns of the RTS occurrences across the circumpolar permafrost region, (ii) assess the environmental factors associated with their occurrence and (iii) create the first susceptibility map for RTS occurrence across the Northern Hemisphere. Based on our results, we predicted high RTS susceptibility in the continuous permafrost regions above the 60th latitude, especially in northern Alaska, north-western Canada, the Yamal Peninsula, eastern Russia and the Qinghai-Tibetan Plateau. The model indicated that air temperature and soil properties are the most critical environmental factors for the occurrence of RTSs on a circumpolar scale. Especially, the climatic conditions of thaw season were highlighted. This study provided new insights into the circumpolar susceptibility of ice-rich permafrost soils to rapid permafrost-related hazards like RTSs and the associated impacts on landscape evolution, infrastructure, hydrology and carbon fluxes that contribute to global warming.

Organization: Government of Yukon | Gouvernement du Yukon
Geology and U-Pb zircon geochronology of upper Dorsey assemblage near the TBMB claims, upper Swift River area, southern Yukon

Meta-sandstone, siltstone and phyllite, with marble and intermediate-to-felsic tuffaceous horizons, host the Munson (TBMB) and Mod zinc-lead occurrences, about 7 km southwest of the Dan and Crescent properties. These host rocks are part of the Late Devonian Dorsey assemblage. Complexities resulting from isoclinal folding and faulting inhibit direct correlation of strata from one ridge exposure to another.
The strata are overlain by dark meta-siltstone of the mid-Mississippian Swift River succession. Although faulted, the lack of a strong lithologic contrast between the units suggests only minor dislocation.
Pre-Jurassic and Cretaceous granites and a diorite sill intrude the Dorsey rocks. Chloritic tuffaceous layers host showings of pyrrhotite, chalcopyrite and sphalerite; carbonate pods contain sphalerite + galena ± pyrrhotite; and quartz-feldspar meta-tuff layers are pyritic.
U-Pb zircon age results for leucosome from a nearby exposure of lower Dorsey rocks indicate an approximate crystallization age of 373 Ma, and about 358 Ma for a granitic dyke in the upper Dorsey assemblage, bracketing the age of deposition of this Yukon-Tanana Terrane assemblage.

Organization: Government of Yukon | Gouvernement du Yukon
Natural Vegetation Succession & Sustainable Reclamation at Yukon Mine and Mineral Exploration Sites

In the Yukon, the goal of most reclamation programs is to return disturbed lands as close to their original wildlands state as is feasible. The revegetation process, an integral component of reclamation, can be manipulated in ways to reflect this ultimate land use objective. The report reviews past Yukon reclamation practices and looks at how natural successional processes can be encouraged on lands disturbed by mining and mineral exploration practices.

By examining the factors that affect the successional patterns of revegetation on disturbed sites, and by noting the composition of plant communities that colonize these areas, the most appropriate pioneering shrub species can be selected for assisted revegetation programs. The species selected for revegetation must reflect each site's ecological variables, as well as the nature of the mining-related disturbances. The reclamation potential of Yukon native shrub species is discussed in this report, along with techniques for assisted revegetation, including the collection of plant materials and propagation methods.

The reclamation capabilities of 23 locally occurring shrub species is appended to this report. This information has been extracted primarily from vegetation experimentation in Alaska and northern Alberta. In order to determine whether these native shrubs are viable as species for reclamation work in the local environment, seeding and planting trials are recommended at Yukon mine and mineral exploration sites.

Organization: Government of Yukon | Gouvernement du Yukon
Glenlyon project: Preliminary stratigraphy and structure of Yukon-Tanana Terrane, Little Kalzas Lake area, central Yukon (105L/13)

Yukon-Tanana Terrane in Little Kalzas Lake area consists of a lower quartzite package and an upper metavolcanic package. The lower quartzite package includes a discontinuous metavolcaniclastic and mafic metavolcanic unit. The upper metavolcanic package consists predominantly of intermediate to felsic metavolcanic rocks in the northern part of the map area. These rocks pass southward into a clastic-dominated metavolcanic assemblage. A conspicuous crinoidal marble occurs in the middle of the upper metavolcanic package and can be traced between the northern and southern domains.

The layered metamorphic rocks are intruded by the multi-phase Little Kalzas orthogneiss complex in the northeastern part of the map area along the southwestern side of Tintina Trench. The Little Kalzas orthogneiss complex, of uncertain age, comprises granodioritic to granitic gneiss and contains abundant xenoliths of country rock. Younger (Jurassic?), post-kinematic quartz monzonite (in the north) to quartz-diorite (in the south) plutons also intrude the area. The youngest intrusive rocks are small plugs of Tertiary quartz-feldspar porphyry.

A pervasive transposition foliation and mineral lineation are developed throughout the area, except in local low-strain domains where primary textures are preserved. The transposition foliation is axial-planar to tight south southwest-vergent folds whose axial surfaces become progressively upright to south southwest-dipping toward the northeast. These structures are deformed by younger crenulation cleavages and associated open folds.

Organization: Government of Yukon | Gouvernement du Yukon
Geological Mapping in the Campbell Range, Southeastern Yukon (Parts of 105 G/8, G/9 and 105 H/5, H/12)

The Finlayson Lake fault zone forms the boundary between autochthonous North American rocks and rocks of the innermost accreted Slide Mountain and Yukon-Tanana terranes in southeastern Yukon. Geological mapping at
1::50 000 scale in a well exposed area of the Campbell Range, southeastern Yukon, was undertaken to examine the kinematics of the Finlayson Lake fault zone and rock types of the Slide Mountain terrane.

Five units were identified: (1) chloritic schist and phyllite, (2) laminated metachert and carbonaceous black slate, (3) tan weathering metachert and maroon siliceous and argillaceous metasiltstone, (4) greenstone and associated breccia, gabbro, metagreywacke, metachert and maroon metasiltstone and (5) serpentinite. Unit 2 is structurally interleaved with submap-scale bodies or layers of serpentinite, hornblende-plagioclase porphyry, plagioclase-potassium fledspar porphyry, quartz-eye muscovite-chlorite phyllite or schist, chloritic schist and minor grey, calcareous metacarbonate. Serpentinite is also exposed in unit 4 and as small slivers along the thrust contact between units 3 and 4.

Lithologically, units 4 and 5 are similar to the upper division of the Slide Mountain terrane in east-central and north-central British Columbia. Unit 2 has similarities with the lowest division of the Sylvester allochthon and is tentatively correlated with the Slide Mountain terrane. Maroon metasiltstone in unit 3 is indistinguishable lithologically from metasiltstone in the overlying greenstone unit suggesting that the eastern thrust fault juxxtaposes parts of the same depositional sequence, ie. The Slide Mountain terrane. Regional correlation of unit 1 is unclear.

Unit 2 is inferred to be bounded to the east and west by northwest-striking faults and to the south, by an east-striking, steeply dipping, normal (north-side down) fault. The northern boundary of unit 2 is unconstrained. Greenstone (unit 4) is thrust towards the southwest over unit 1 in the western part of the map area along a northwest-striking, gently northeast-dipping thrust fault. In the eastern part of the map area, greenstone is thrust towards the northeast over unit 3 along a northwest-striking, moderately southwest-dipping thrust fault. Outcrop data and topographic patterns suggest that the eastern thrust fault is truncated by a northwest-striking, steeply dipping fault and that the normal fault truncates the westernmost northwest-striking fault. The northwest-striking faults are poorly exposed and their kinematics have yet to be determined. However, if they are steep faults, they are likely dextral strike-slip faults.

Field data indicate that the Finlayson Lake fault zone consists of diverging thrust faults and subparallel strike-slip(?) faults. These structures are consistent with the interpretation of the Finlayson Lake fault zone as a transpressive fault zone. More constraints on the relative timing of faulting and the kinematics of the steep faults are required to test this hypothesis,

Organization: Government of Yukon | Gouvernement du Yukon
Mel property, southeastern Yukon

The Mel deposit consists of a concordant, folded lens of barite and coarse recrystallized galena and sphalerite at the contact between Cambro-Ordovician limestone and shaly limestone. Based on diamond drilling since 1972, the deposit contains geological reserves of 6,200,000 tons grading 6.77% Zn, 1.92% Pb and 49.6% barite to a depth of 457 m. The mineralization is open to depth and the higher grade part of the deposit lies below 305 m.

Organization: Government of Yukon | Gouvernement du Yukon
Logan property, southeastern Yukon

Sphalerite and tetrahedrite occur with arsenopyrite and minor chalcopyrite and galena in a tabular, fault-bounded body which cuts granitic rocks of the Cassiar batholith. Diamond drilling between 1986 and 1988 outlined a deposit 1100 m long and 50-100 m wide containing geological reserves of 12.3 million tonnes grading 6.17% Zn and 26 g/t Ag. These reserves are amenable to open pit mining and the deposit is open to depth.

Organization: Government of Yukon | Gouvernement du Yukon