The Haggart Creek study area contains unconsolidated sediments, which represent six main geomorphic settings: 1) Reid-age glacial and glaciofluvial deposits; 2) McConnell-age proximal braided stream deposits to periglacial alluvial fans; 3) McConnell-age medial to distal braided stream deposits; 4) post-McConnell wandering gravel bed river; 5) Holocene gulch deposits; and 6) Holocene colluvium. Placer gold within the study area is known to originate from at least two main local lode sources: 1) gold in sheeted quartz veins within a Late Cretaceous-age granodiorite stock; and 2) gold in isolated quartz-sulphide fissure veins found in bedrock along Haggart Creek. Placer gold is believed to have formed as a result of reworking and re-concentration of gold during interglacial times, as well as reworking of older auriferous interglacial gravel by McConnell-age periglacial alluvium. The primary setting for placer gold deposits is Late McConnell to Early Holocene alluvium, on or near bedrock. Sub-crystalline to crystalline placer gold grains recovered from sediments found far removed from currently known local bedrock sources suggests that other lode sources may be present within the study area. A copy of this thesis is available at the EMR library – QE195.W47 1999. This thesis is available online at http://hdl.handle.net/1880/25379.

Placer gold deposits in the Indian River area, west-central Yukon, are grouped into five classes based on thickness, grain size, composition, age, process, landform and exposure. The placers vary from 1.5-16 m in thickness and consist of slightly muddy, sandy gravel that is dominated by either vein quartz clasts, or igneous and metamorphic clasts. The gravel was deposited on floodplains, now preserved as terraces and creek and river valley fills, that range from Pliocene(?) to Holocene in age. The formation of the placers is related to a hierarchy of physical scales: at the lithofacies scale (ms), bed roughness determined sites of gold deposition; at the element scale (10s of ms), gravel bars were preferentially enriched in gold; at the reach scale (100s of ms), stream gradient was an important factor; at the system scale (100s of kms), braided river environments transported large amounts of gold; and at the sequence scale (1,000s of km 2 ), economic placers formed in the White Channel Gravel unit in downstream parts of the Indian River drainage, and in upstream parts of the drainage in the unit herein referred to as the Local Creek Gravel.

Dominion Creek and its tributaries (Sulphur and Gold Run creeks) are one of the largest placer gold producing areas in North America. The placer gravel is divided into: (1) Pliocene White Channel gravel, (2) Pleistocene terraces, (3) early Pleistocene incised-valley gravel (Ross gravel), (4) Pleistocene Dominion Creek gravel, and (5) creek and gulch deposits. Paleomagnetically, the White Channel gravel is normally magnetized at one site, suggesting a pre-Brunhes normal chron (likely recording the Gauss chron, or an earlier sub-chron older than 2.6 million years). These results are broadly similar to those paleomagnetic investigations of the White Channel gravel in the Klondike River drainage. The Ross gravel is magnetically reversed and may be correlated to the Matuyama reversed chron (older than 780,000 years). Furthermore, the Ross gravel has a younger normally magnetized alteration overprint presumably of Brunhes age (younger than 780,000 years). Dominion Creek gravel overlies the Ross gravel in lower Dominion, Sulphur and Gold Run creeks, and at all sites sampled revealed normal polarity, presumably of Brunhes age (younger than 780,000 years). Radiocarbon ages from the Dominion Creek gravel range from older than 47,000 years BP to 6000 years BP, and likely represent a composite unit of fluvial activity over the last several hundred thousand years. The oldest and volumetrically largest placer deposits are associated with the Ross gravel, and little gold appears to have been subsequently mobilized from bedrock sources during the last 800,000 years. Gold within Dominion Creek deposits is largely flat, rounded and well travelled,suggesting the main source was likely near King Solomon Dome in the headwaters of the basin.

Placer deposits in the Mayo area occur in a wide variety of geomorphic settings, including alluvial fans, gulch gravels, valley-bottoms (alluvial plains), and bedrock terrace (bench gravel) settings which have been variably buried and reworked by glaciofluvial processes. Placer gold is also known to occur in glacial till and glaciofluvial gravels especially where these sediment types are close to bedrock. Three major Quaternary glaciations (the pre-Reid, Reid and McConnell, in order of oldest to most recent) and their associated interglacials have modified the drainage and topography of this area, and these events have affected the formation, preservation and proportionate size of the District's placer gold deposits. Duncan Creek, a tributary of the Mayo river which drains Mayo Lake, is one of the most actively-mined drainages in the Mayo District. Placer mining began in the Duncan Creek area in the early 1900's and has continued almost continuously to the present day. Gold production from Duncan Creek in the last 15 years has been nearly 20,000 crude ounces, with historical production estimated to be at least twice that for the last 95 years. Although the McConnell ice limit only reached into the first few kilometres of the Duncan Creek valley at its mouth and its headwaters, associated glaciolacustrine and glaciofluvial sediments have inundated the valley to depths of up to 40 or more metres. Gold-bearing gravels are currently being mined beneath this thick cover of barren overburden. Preliminary sedimentological and stratigraphic data indicate three main lithostratigraphic assemblages:: 1) Crudely stratified, imbricate boulder-cobble gravel and muddy boulder-cobble diamict; 2) Stratified cobble-pebble gravel, stratified sand and laminated silt; and 3) Stratified silt, massive boulder-cobble gravel and silty boulder diamict. Lithostratigraphic assemblage 1 is gold-bearing and is interpreted as Reid-age subglacial or proximal glaciofluvial outwash and Reid-age proximal alpine glacial till. Gold in these sediments is concentrated either as a function of hydraulic interaction with bedrock topography, or as a result of incorporation and dispersion of a pre-existing placer deposit formed during a previous interglacial period. Lithostratigraphic assemblage 2 is interpreted as an interglacial wandering gravel bed river indicated by several fining upward sequences and wood radiocarbon dated at 32 320a. ±1270 B.P. (Beta-86851). Lithostratigraphic assemblage 3 is interpreted to be McConnell age glaciolacustrine silt, glaciofluvial outwash and glacial till. The Keno Hill Silver District (United Keno Hill Mines) lies a few kilometres upstream of the placers and native silver nuggets have been recovered during present and historic placer mining. Lode sources of gold are also known to occur on nearby Mt. Hinton, which indicates the gold in the placers is likely from local bedrock sources. The ubiquitous and extensive nature of facies assemblage 2 combined with the possible existence of other hardrock sources of gold indicates that a significant potential exists for more placer gold reserves in the same drainage.

Twelve lithostratigraphic units, including ten autochthonous and two allochthonous units, are recognized, and most of these are divided into 27 subunits. They range from Cambrian to Quaternary in age and include a wide range of sedimentary, igneous and metamorphic rock types. Lower Cambrian siliciclastic and carbonate rocks of the Cassiar Batholith predominate. Three phases of structures are identified. First phase structures include bedding and slaty cleavage, of which the latter is attributed to late stage diagenetic recrystallization. Second phase structures trend northwest and include crenulation cleavage and related folds and lineations. They are attributed to northeast-southwest compression resulting from accretion and obduction of allochthonous rocks during arc-continent collision in Late Jurassic-Early Cretaceous time. Third phase structures are approximately 90° to the second phase structures and trend northeast. They include joints and related folds and lineations and are attributed to dextral transcurrent movement on Tintina, Kechika and Cassiar faults. Precious and base metal mineralization is found mostly within Paleozoic sedimentary rocks and Cretaceous plutonic rocks and forms predominantly veins and replacement lenses. The dominant sulphides include galena, sphalerite, pyrite and chalcopyrite. Arsenopyrite, freibergite, tetrahedrite, pyrrhotite, wolframite, cassiterite, stannite, fluorite and lepidolite are also present. Common gangue minerals include quartz, siderite and iron and manganese oxides. Mineralization appears to be structurally controlled by the northeast-southwest jointing and, to a lesser extent, lithologically controlled by limestone-phyllite contacts. It is attributed to hydrothermal solutions migrating along the joints and was probably deposited approximately 50 Ma ago. The most useful exploration guide to finding additional mineralization is iron and manganese gossans.

Historic placer mining areas in Yukon can be grouped into ten areas: Klondike; Sixtymile; Fortymile; Clear Creek; Moosehorn Range; Stewart River; Clear Creek; Mayo; Dawson Range; and Livingstone Creek. Each area has its own geomorphic setting and depositional history which is related to its glacial history. Several Quaternary glacial advances have been described in Yukon, and these are generally divided into three episodes, commonly known as the pre-Reid, Reid and McConnell, in order of oldest to most recent. Placer deposit in the unglaciated Klondike, Sixtymile, Fortymile and Moosehorn drainages occur in valley-bottoms, alluvial fans, in gulch gravels and as high level terraces. Placer deposits in glaciated areas occur in variably reworked and buried valley-bottom, bench and gulch settings, in auriferous glacial till and glaciofluvial gravels, and in non-glacial gravels which were deposited on top of glacial drift. Targets for new placer deposits in unglaciated areas include drainages such as Stewart, North Ladue and Yukon Rivers which lie outside of the pre-Reid glacial limit. Mineable placer deposits may also have formed on top of pre-Reid glacial drift and may be buried in valleys beneath Reid-age non-glacial alluvium. Prospective areas of this type are drainages which are near lode gold deposits in the Clear Creek area and in drainages near felsic volcanics in the Dawson Range. At the limits of both the Reid and McConnell glaciations, auriferous pre-glacial or interglacial gravel can often be buried by glacial and glaciofluvial deposits. Low-grade auriferous glaciofluvial gravel can also be derived form the reworking of pre-glacial gold-bearing gravel. Prospective areas for these types of placer deposits are the South McQuesten River valley and the creeks draining the Ruby Range on the east side of Kluane Lake. Within the McConnell glacial limits, placer deposits may be found in valleys oriented obliquely to the paleoflow direction of the glacial ice. Economic to sub-economic placers may also be found along meltwater channels within the McConnell ice limit. Prospective areas of this type of deposit are the drainages which lie to the north of Livingstone placer camp. The possibilities for new placer mining areas within glaciated areas must be investigated, and new placer gold reserves will undoubtedly be found within these areas. These potential gold deposits may be explored by techniques such as surficial mapping, airphoto interpretation and bulk sampling of potential gold-bearing units.

Placer gold deposits are widespread throughout the largely unglaciated Stewart River and southern part of the Dawson map areas. These deposits include the world famous Klondike goldfields, the historic Fortymile and Sixty Mile goldfields, and well known placers along Black Hills, Scroggie, Thistle and Kirkman creeks. Although the deposits have been mined for over 100 years and have produced an estimate 311 tonnes of gold, they still account for about 85% of Yukon's annual placer gold production. The placer deposits are classified into three levels of gravel with four main units: high-level gravel, which usually forms prominent, continuous high-level terraces and is subdivided into the White Channel Gravel (which is locally subdivided into a lower White Gravel and an upper Yellow Gravel unit) and Klondike Gravel; intermediate-level gravel, which mostly forms relatively small, irregularly distributed intermediate to low-level terraces; and low-level gravel, which represents alluvium along present day creeks, gulches and rivers. The White Channel Gravel, is up to 46 m thick and characterized by a predominance of quartz clasts (which are generally more abundant in the White Gravel than in the Yellow Gravel). It is considered Early Pliocene to earliest Late Pliocene in age (~5 to 3 Ma). The Klondike Gravel, not considered an economical placer, is up to 53 m thick and is distinguished by chert clasts derived from the Ogilvie Mountains, located northeast of the map areas. It was deposited as glaciofluvial outwash during the end of the initial and most widespread of the pre-Reid glaciations, and is probably latest Early Pliocene to earliest Late Pliocene (~3 Ma). The intermediate-level gravel, the least important economically, is up to 9 m thick. The low-level gravel, historically the most important gold-bearing unit, is 5 m thick in creeks and up to 20 m thick in rivers. The intermediate-level and low-level gravel have similar amounts of quartz, igneous and metamorphic rock particles, although locally, the low-level gravel contains sedimentary rock particles. The intermediate-level gravel is thought to be Late Pliocene to Early Pleistocene (~3 Ma to 750 Ka) in age and the low-level gravel is considered Late Pleistocene to Holocene in age. Practically all of the placers are fluvial in origin and were deposited primarily in braided streams that flowed parallel to the present day streams along which the deposits occur. Gold recovered from the various levels of gravel is detrital in origin and was mainly derived from early Mesozoic auriferous quartz veins. The concentration of gold in the gravel is related to a hierarchy of physical scales: at the lithofacies scale (metres), bed roughness determined sites of gold deposition; at the element scale (tens of metres), gravel bars were preferentially enriched in gold; at the reach scale (hundreds of metres), stream gradient was an important factor; at the system scale (hundreds of kilometres), braided river environments transported large amounts of gold; and at the sequence scale (thousands of kilometres), economic placers formed initially in the high-level White Channel Gravel and later in the intermediate- and low-level gravel.

Historic placer mining areas in Yukon can be grouped into ten areas: Klondike; Sixtymile; Fortymile; Clear Creek; Moosehorn Range; Stewart River; Whitehorse South; Mayo; Dawson Range and Livingstone Creek. Each area has its own geomorphic setting and depositional history which is related to its glacial history. Several Quaternary glacial advances have been described in Yukon, and these are generally divided into three episodes, commonly known as the pre-Reid, Reid and McConnell, in order of oldest to most recent. Distributed from [GeoYukon](https://yukon.ca/geoyukon) by the [Government of Yukon](https://yukon.ca/maps) . Discover more digital map data and interactive maps from Yukon's digital map data collection. For more information: [geomatics.help@yukon.ca](mailto:geomatics.help@yukon.ca)

Within the Sixtymile River drainage basin, Quaternary placer deposits include tributary valley bottom gulch gravel, a broad main valley alluvial plain, and high level terrace systems in both tributary and main valley settings. After downcutting, paleo-Miller Creek underwent valley widening during alluvial fan erosion and sedimentation. During this time, the main Sixtymile River valley was also being laterally eroded during braidplain aggradation. Terrace development and incision through both fan and braidplain sediments coincided with significant debris flow sedimentation. The Sixtymile River changed from a braided environment to single channel meandering environment during terrace development. Incision of Miller Creek through the fan surface to present levels probably coincided with downcutting of the Sixtymile River. Economic concentrations of placer gold are found in:: 1) the upper Miller Creek terrace where coarse-grained, massive and angular flood flow gravel forms a crude pay streak above the bedrock surface; 2) the distal Miller Creek terrace where discontinuous concentrations of gold were formed over a broad paleo-surface of lag gravel prior to fan aggradation; 3) laterally discontinuous pockets in the main Sixtymile valley terrace which was originally part of an aggraded braidplain sequence; and 4) lower, but still economic placer concentrations in gravels of the alluvial plain in the main Sixtymile valley.