A copy of this thesis is available at the EMR library – QE195.V35 1982.

The study area is underlain by four stratigraphic successions ranging in age from Middle Proterozoic to Early Paleozoic. From oldest to youngest, they are: Middle Proterozoic Wernecke Supergroup; Middle to Upper Proterozoic Pinguicula Group; Upper Proterozoic Windermere Supergroup; and Uppermost Proterozoic to Lower Paleozoic sandstone and carbonate. Together, they represent about a billion years of intermittent sedimentation punctuated by processes such as deformation, uplift, erosion, magmatism and mineralization. Rocks in the study area record eight phases of contractional and extensional deformation, some of which may be related to strike-slip faulting. Two phases of southwest-verging folds and thrust faults may be related to dextral transpression on the Snake River Fault. Mineral enrichments occur in two general forms:: breccia-related (Middle Proterozoic), and veins (Mesozoic to Tertiary). The breccia-related occurrences have enrichments of Cu ± U, Co, Au and Ag, as dissemminations and veinlets in and near intrusive breccia zones (Wernecke breccia). The vein occurrences comprise Zn-Pb-Ag ± Cu and Au, in veins and related lenses and irregular replacements of carbonate.

Paleozoic rocks of the Pelly Mountains, central Yukon, preserve greater than 150 m.y. of sedimentation, magmatism and base-metal mineralization. To identify secular trends in regional tectonics and metallogeny, a multi-year project on the stratigraphy of the Pelly Mountains in the Quiet Lake (105F) and Finlayson Lake (105G) map areas was initiated. Field studies during summer 2015 focused on two stratigraphic intervals: (1) mafic volcanic, volcaniclastic and clastic rock successions assigned to the Cambrian-Ordovician Cloutier and Groundhog formations (Kechika group); and (2) felsic volcanic, volcaniclastic and clastic rock successions assigned to the Devonian-Mississippian Black Slate and Felsic Volcanic formations (Seagull group). Cambrian-Ordovician strata were deposited in a marine environment characterized by episodic mafic volcanism and extensional tectonism. Devonian-Mississippian strata record the transition from an extensional turbidite basin to a metalliferous volcanic rift basin, and resemble key rock assemblages of the Selwyn basin (Earn Group) and Yukon-Tanana terrane (Grass Lakes and Wolverine Lake groups).

The Quartet Lakes map area is underlain by rocks that range in age from Early Proterozoic to early Paleozoic. Stratified rocks include, from oldest to youngest, the Lower Proterozoic Fairchild Lake and Quartet groups (Wernecke Supergroup), the Middle to Late Proterozoic Tsezotene Formation, Katherine Group, and Little Dal Formation Mackenzie Mountains Supergroup), and the Cambrian Slats Creek Formation. Five igneous units are recognized, including the Early Proterozoic Bonnet Plume River Intrusions, the Middle Proterozoic Bear River dykes, the Late Proterozoic Tsezotene Sills, Late Proterozoic to Cambrian lamprophyre, and Late Proterozoic to early Paleozoic diorite. Older rocks (Wernecke Supergroup, Wernecke Breccia and Bonnet Plume River Intrusions) were thrust northward over the Mackenzie Mountains Supergroup along a portion of the Knorr Fault. This part of the fault may be a restraining bend in an otherwise dextral strike-slip system. Copper-golduranium mineral occurrences in the area include disseminated and vein mineralization associated with zones of Wernecke Breccia.

Geochemical, isotopic and U-Pb dating studies of volcanic rocks of the Tlansanlin Formation in central Aishihik Lake map area (115H) show that these are Late Cretaceous (75.8 ± 0.4 Ma to 77.3 ± 1.3 Ma), relatively primitive magmas that were emplaced in a continental arc setting. Intrusive rocks in the immediate area, associated with the Hopper porphyry and skarn and Sato porphyry occurrences (Yukon MINFILE 115H 019, 021, respectively), are similar in age and composition to the Tlansanlin Formation rock units, confirming the presence of a significant Late Cretaceous igneous and mineralizing event in the area. Significant porphyry and skarn occurrences associated with the Late Cretaceous intrusions in the Aishihik Lake area, as well as the important mineral deposits and occurrences associated with this magmatic event in the Dawson Range to the northeast (e.g., Casino, Revenue-Nucleus, Sonora Gulch), underscore the metallogenic potential of this previously poorly recognized magmatic event.

Cassiterite (SnO2), a main ore mineral in tin deposits, was collected by multiple Russian geologists or obtained from museum collections in both the USA and Russia and dated at the U.S. Geological Survey. The dated samples represent four different mining districts spanning the entire country from the village of Pitkäranta in the west (31° E Longitude) to the Merekskoe Deposit in the Russian Far East (134°E Longitude). The samples were recovered from a variety of host deposit types that range from the Proterozoic to Phanerozoic. Cassiterite (in the form of mounted loose grains) was prepared and analyzed for direct age dating on a laser ablation inductively coupled plasma mass spectrometer (LA-ICP-MS) system at the USGS in Denver, Colorado from February 2017 to October 2019. This data supports the following associated publication: Neymark, L.A., Larin, A.M., and Moscati, R.J., 2021, Pb-Pb and U-Pb dating of cassiterite by in situ LA-ICPMS: Examples spanning ~1.85 Ga to ~100 Ma deposits in Russia and implications for dating Proterozoic to Phanerozoic tin deposits, Minerals.

The Proterozoic to Cambrian carbonate rocks of the Bonnet Plume area are hosts to many lead-zinc occurrences. Some are classified as Mississippi-Valley-type deposits (MVTs) while others are thought to be veins. Six of the showings were sampled during the summer of 2000 for isotopic age dating (Pb/Pb) in order to help clarify classification and shed light on the timing of the different mineralization sources and processes. Preliminary results show that some occurrences previously described as MVTs contain surprisingly high amounts of silver or antimony, elements usually indicative of higher temperatures than those usually associated with MVT deposits; while some evidence of stratigraphic replacement is observed in "vein" occurrences.

Four main styles of quartz veining are recognized in the Klondike District. These include foliaform and discordant mesothermal quartz veins in schistose metamorphic rocks, quartz-carbonate veins in altered ultramafic rocks and greenstones, epithermal chalcedony veins cutting Eocene igneous and sedimentary rocks, and low-temperature epithermal veins associated with intensely altered Plio-Pleistocene White Channel Gravel deposits. Foliaform mesothermal quartz veins are invariably barren; however discordant mesothermal veins locally contain visible gold. Both styles of epithermal veins in the Klondike contain at least geochemically anomalous levels of gold. The complex history of hydrothermal activity in the Klondike has led to considerable confusion about the nature of veining in this area. The results of this study provide a preliminary framework within which to evaluate the various prevailing theories regarding the major sources of gold in the Klondike placer deposits.

Yukon-Tanana Terrane in Grass Lakes map area south of Finlayson Lake consists of highly deformed though regionally mappable metasedimentary and metavolcanic rocks. Four newly revised map units and various subunits have been traced throughout the area. These include unit 1, a quartz-rich metaclastic unit with felsic metavolcanic rocks at its lowest exposed level and a middle calcareous marker; unit 2, a mafic metavolcanic unit with lesser carbonaceous metasedimentary rocks; unit 3, a carbonaceous phyllite and quartzite and felsic metavolcanic unit, and unit 4, an upper unit of carbonaceous phyllite, mafic metavolcanic rocks and coarse-grained quartzofeldspathic metaclastic rocks. Units 2 and 4 have been redefined from a previous report based on new observations and a consideration of the provenance of coarse-grained quartzofeldspathic metaconglomerates now included in unit 4. In the current interpretation, the metaconglomerate-bearing strata north of and overlying the felsic meta-volcanic rocks hosting Kudz Ze Kayah are considered to unconformably overlie them. Three of these map units are associated with mineral occurrences or deposits. Rusty, locally malachite-stained muscovite-quartz schist at Arcturus Resources' First Base claims and Expatriate Resources' Blue Line and Winger claims belong to the felsic metavolcanic part of unit 1. Columbia Gold's Fyre Lake deposit is hosted in unit 2 mafic metavolcanic rocks, possibly associated with a synvolcanic fault. Cominco's Kudz Ze Kayah deposit occurs in unit 3 felsic metavolcanic rocks. Gossans on Cominco's Cobb claims, Expatriate's Overtime and NHL claims, and Atna/Westmin's Pack claims and anomalous copper in soils at Arcturus' Bas claims are also spatially associated with this unit.

This data set contains 3 tables containing uranium-lead (U-Pb) isotopic data and crystallization ages of zircon and titanite from igneous, metamorphic, and sedimentary rocks collected from the Yukon-Tanana upland of eastern interior Alaska between 2013 and 2019. Bulk samples of igneous and metamorphic rocks were processed into concentrated mineral separates of zircon and (or) titanite in USGS laboratories in Denver, Colorado, or by Apatite to Zircon, Inc. (A2Z) and analyzed by USGS research scientists at the Stanford-USGS Sensitive High Resolution Ion Microprobe with Reverse-Geometry (SHRIMP-RG) at Stanford University. Bulk samples of sedimentary and metasedimentary rocks were processed into concentrated mineral separates of detrital zircon and analyzed by Apatite to Zircon, Inc. and GeoSep Services (GSS) using laser-ablation-inductively-coupled-plasma-mass spectrometry (LA-ICP-MS) techniques. The 2 data tables (geology_detritalZircon_easternAK_Jones.csv; geology_SHRIMPRGData_easternAK_Jones.csv) accompanying this data release report the isotopic composition of uranium (U) and thorium (Th) measured in each grain, ratios of two isotopes of lead (207Pb and 206Pb) and two isotopes of uranium (235U and 238U), and the age of each grain. A third table (geology_sampleSummary_easternAK_Jones.csv) reports sample locations, rock characteristics, and interpreted ages. The SHRIMP-RG data table (geology_SHRIMPRGData_easternAK_Jones.csv) also reports concentrations of selected trace elements measured in each grain.