This study identifies Late Quaternary glacial ice-flow direction in east-central Ellesmere Island, N.W.T., by the study of its composition and its relation to bedrock sources. The spatial distribution of five till types suggests a hypothesis which attempts to reconcile the Innuitian Ice Sheet model of Blake with the Franklin Ice Complex model of England. Glaciers draining from ice sheets in northern Ellesmere Island and Greenland filled Kane Basin and flowed southward toward Smith Sound. When this southward-flowing ice reached the bottleneck at Smith Sound (40 km wide), it overrode the adjacent landmasses of Pim Island and Cape Herschel and forced Buchanan Bay ice southward through the channel that is now occupied by Rice Strait. Southward-flowing ice continued to drain towards Baffin Bay, overriding the coastal areas of Nares Strait at Wade Point and Cape Isabella. The results presented here partially support the Innuitian ice sheet hypothesis, but do not negate the Franklin Ice Complex model. (Abstract shortened by UMI.)

Thermokarst sedimentology is the study of the sedimentary processes and facies associated with thermokarst. Using facies analysis, oxygen isotopes and observations of processes in the Tuktoyaktuk Coastlands, this thesis (1) classifies frozen ground according to its cryostructures and cryofacies; (2) describes thermokarst facies, facies associations and sedimentary structures; (3) examines the sedimentary processes associated with thermokarst; (4) proposes thermokarst facies models; and (5) proposes criteria for identifying thermokarst-modified sediments. The thermokarst sedimentary system of the Tuktoyaktuk Coastlands comprises uplands, slopes and basins. Beneath ice-rich uplands, downwearing thermokarst produces a thick ($\le$c. 2.5m) thaw layer in which sediments melt-out from underlying permafrost. Ice-rich slopes are subdivided into steep icy slopes and retrogressive thaw slumps, the former occurring where the percentage of excess ice in upland materials is less than c. 30-40%, the latter where it exceeds this value. As slopes retreat by backwearing thermokarst, upland materials are redeposited by alluvial and colluvial processes. Thermokarst basins form where back- and downwearing thermokarst coincide. In deep non-oriented basins containing thermokarst lakes, three stages of basin infilling are identified. The first occurs during early and rapid basin expansion, when intense backwearing thermokarst at basin margins transports large quantities of upland materials into the basins. This pulse of resedimentation initiates sublacustrine benches. The second stage beings as the rate of basin expansion diminishes, reducing the influx of clastic sediment into lakes; thus the tops of sublacustrine benches are reworked and the main depositional process changes to suspension settling in basin centres. The final stage, commencing as lakes drain, involves basin infilling by peat accumulation and by gelifluction and aeolian deposition. Two sedimentary structures relating to thermokarst are frost-fissure pseudomorphs and thermokarst involutions. Frost-fissure pseudomorphs develop through thaw-modification processes: slow subsidence, thermal erosion, refreezing, loading, buoyancy, spreading, folding, shearing and mass movement. Thermokarst involutions form primarily by water-escape or by loading and buoyancy. Involutions within a thick palaeothaw layer probably reflect the massive scale of soft-sediment deformation that accompanies regional thermokarst, and they provide a potential analogue for some Pleistocene involutions in the mid-latitudes. Five criteria identify thermokarst-modified sediments in the Tuktoyaktuk Coastlands: (1) organic-rich (and sandy) diamicton; (2) granular mud aggregates in stratified facies; (3) impure sand ($\pm$diamicton); (4) frost-fissure pseudomorphs; and (5) thermokarst involutions.

Differences in permafrost conditions between the Qinghai-Xizang (Tibet) Plateau and the Mackenzie Delta region primarily relate to their Quaternary histories and their current climates. For example, the Tibetan Plateau has experienced uplift of at least 3,000 m during the last 2 million years. Under the present climatic conditions, the lower altitudinal limit of the plateau permafrost in the north is at 4,150 m a.s.l. This suggests that if the Plateau were 1,000 m lower than its present elevation, there would be no permafrost. During the Quaternary, the Tibetan Plateau remained unglaciated. This has meant that little water was available for the formation of massive ground ice, in contrast to the Mackenzie Delta region. Located at 68-69$\sp\circ$N, the Mackenzie Delta region experiences a combination of low air temperature in winter, a long solar night and a short thaw period in summer. The result is a relatively thin active layer. Located at 30-34$\sp\circ$N, the Tibetan Plateau experiences much higher solar insolation, and a diurnal temperature rhythm. The thickness of the active layer is much greater than in the Mackenzie Delta region and varies between 1.3 and 3 m or more. Permafrost on the Tibetan Plateau is much warmer and thinner than that in the Mackenzie Delta region. One consequence is that it is more sensitive to any changes in climate and surface conditions. Deep ground temperatures in the Pleistocene Mackenzie Delta indicate a recent warming trend, while a cooling trend in the Modern Delta likely relates to local factors such as channel shifting and emergence and/or sedimentation in the Mackenzie River. Water bodies are a cause of geothermal disturbances common to both regions. Numerical simulation of rapid coastal retreat in the Mackenzie Delta region indicates that subsea permafrost is at least 3$\sp\circ$C warmer than adjacent terrestrial permafrost. On the Tibetan Plateau, faulting also disturbs the geothermal regime. Measurements of in situ permafrost creep in the Fenghuo Shan area are one indicator of the warmer permafrost temperatures on the Tibetan Plateau. The average creep velocity ranges from 0.16 cm/year at 2.8 m depth to 0.54 cm/year at 1.6 m depth. These velocities are greater than those recently obtained from the High Arctic of Canada and are approximately of the order of magnitude as those obtained in the Mackenzie Valley. Inter-continental comparison of creep data suggests that climate controls the regional (large scale) magnitude of creep, and that ground ice is a local factor controlling creep rate in a particular area or site. A constitutive relationship (secondary creep power flow law) was applied to the field creep data; and creep parameters A and n were determined for each of the three different depths in the West Valley, Fenghuo Shan area, Tibetan Plateau.

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Calcite cements from the Upper Paleozoic sequences 2, 3 and 4 of the Sverdrup Basin (Canadian Arctic Archipelago) are the subject of this study. On a micro-scale, petrography with light microscopy, cathodoluminescence (CL), scanning electron microscopy (SEM) and staining helped to identify two main textural groups of cements, neomorphic and primary. Both are, in turn, subdivided into two categories: calcitized aragonite and recrystallized high-magnesium calcite for the former, and meteoric calcite and burial (late) calcite, for the latter. In neomorphic cements, eleven micro-scale CL eleven patterns can be recognized. The combination of relationships of these patterns suggests that stabilization operated via numerous diagenetic systems and involved more than one dissolution-reprecipitation step. In an associated trace element study, application of Secondary Ion Mass Spectrometry (SIMS) enabled direct measurements of chemical composition in thin sections, constituting a precedent. The precisions obtained were 12, 6, 6 and 6% for Mg, Fe, Mn and Sr, respectively. Petrographic observations guided the micro-sampling for geochemical studies, including $\delta\sp $C, $\delta\sp $O, $\sp‡$Sr/$\sp†$Sr, Sr, Mg, Fe and Mn. For marine neomorphic cements, the CL patterns--or stages of textural preservation--do not correlate with preservation of the isotopic signal. Many texturally well preserved cements show clearly altered isotopic signatures and vice versa. Moreover, a detailed trace element study of uniform cathodoluminescence zones revealed that cements with less than about 1000 ppm of Fe and 225 ppm of Mn may be luminescent, nonluminescent or dull. The existence of this "undifferentiated" domain implies that the redox sensitive Fe-Mn pair is not the sole control of cathodoluminescence zoning. On a regional scale, analysis of the stratigraphic distribution of cements, and of their geochemical attributes, suggests the following main diagenetic trends in the three carbonate sequences. The general succession consists of (1) early marine cementation, (2) recrystallization of marine cements concurrent with late cementation during shallow burial, mostly in a marine environment, and (3) continuing burial cementation at greater depths. In sequence 2, the western region of the Moscovian Sverdrup Basin was affected by upward migration of oxygenated hot waters. This hydrothermal activity apparently ceased prior to burial. In contrast, the eastern early cements were possibly recrystallized first by cold marine waters following drowning, and subsequently by saline waters during shallow burial. In sequence 3, precipitation of early marine cements has been followed by partial exposure of the sequence to meteoric diagenetic realm that resulted, at least partly, in their dissolution and recrystallization. Through the studied time span, the best $\delta\sp $O and $\delta\sp $C estimates indicate that the Sverdrup Sea composition remained relatively constant. (Abstract shortened by UMI.)

In the Kokanee Range, southeastern British Columbia, more than 370 Ag-Pb-Zn vein and replacement deposits are hosted by the Middle Jurassic Nelson batholith and surrounding Cambrian to Triassic metasedimentary rocks in the hangingwall of the Slocan Lake Fault, an Eocene, east-dipping, low angle normal fault. K-Ar and step heating $\sp{40}$Ar/$\sp{39}$Ar analyses on hydrothermal vein and alteration muscovite indicate that hydrothermal fluids were forming vein and replacement deposits 58-59 Ma ago. A 100 Ma time interval is therefore documented between batholith emplacement and spatially associated mineralisation, ruling out any genetic link between the two. The Pb isotope compositions of galena permit the deposits to be divided into four groups that result from mixing Pb leached from three reservoirs located in the local, upper crustal country rocks, the lower crust, and the upper mantle. Sulfur was derived from local country rocks, and carbon was derived from mantle CO$\sb2$ degassing. The $\rm \delta\sp{34}S\sb{sulphide},$ $\rm \delta\sp O\sb{quartz},$ $\rm \delta\sp O\sb{siderite},$ and galena Pb isotopic ratios from veins display regional zonations revealing fluid flow paths of a large, fossil hydrothermal system. Regional isotopic zonations are controlled by deep fracture zones, such as the Slocan Lake Fault, which channelled lower crustal and mantle Pb, and mantle CO$\sb2$ to higher crustal levels where mixing occurred with upper crustal fluids which had leached local sulfur and upper crustal Pb. Three contrasting fluids are identified: (i) a high salinity, deep-seated and isotopically crust-equilibrated fluid; (ii) a low salinity upper crustal fluid of evolved meteoric origin; (iii) a late stage meteoric fluid. Silver-lead-zinc veins from a distinct type of vein deposit characterised by their mineralogy, form, and metal content. Silver-lead-zinc veins are late orogenic features of metamorphosed sedimentary basins within Pb-Zn metallogenic provinces and commonly occur near large crustal faults.