Geological mapping has defined a distinct group of NNE trending diabase dykes east of the Grenville Front in the Chibougamau area. These dykes are found intruding Archean orthogneisses within a narrow zone, the Parautochthonous terrane, bounded to the northwest by the Grenville Front and to the southeast by the Allochthon Front. The best preserved dykes, exhibiting primary igneous minerals and textures, are located along the Grenville Front, whereas the most metamorphosed dykes (i.e. amphibolites) are located along the Allochthon Front. The dykes are tholeiizic to weakly alkaline and can be divided into four main groups, based on texture and certain major and trace elements: (1) low-TiO$\sb2$; (2) high-TiO$\sb2$; (3) high-TiO$\sb2$ segregations; and (4) high-Al$\sb2$O$\sb3$. Igneous minerals include olivine, augite, plagioclase, magnetite, biotite, and pargasite. The principal metamorphic minerals are enstatite, hornblende, spinel, corundum, garnet, albite, and quartz. (Abstract shortened by UMI.)

At least 36 decametre-scale, largely symmetric high-frequency cycles spanning approximately 15 Ma make up the carbonate-dominated succession of Lower Permian sequence 3 of the Sverdrup Basin in Fosheim and Hamilton peninsulas. These cycles record a rift pulse caracterized by the uplift, passive subsidence, collapse and passive subsidence of the Fosheim-Hamilton subbasin and show that during the rifting phase of the Sverdrup Basin deposition of conformity-bounded sequences was tectonically rather than eustatically controlled. The active rifting-phase of the Sverdrup Basin comprises four unconformity-bounded sequences that range in age from Visean to Kungurian. The third-sequence in Fosheim and Hamilton peninsulas area, west central Ellesmere Island comprises six formations. The Canyon Fiord Formation is composed of lithofacies ranging from basin margin fluvial to marine siliciclastics. The Belcher Channel, Antoinette, Tanquary and Nansen formations are made up of inner- to midshelf carbonates that encompass the Mount Bayley Formation, a thick evaporite succession deposited within the Fosheim-Hamilton subbasin. Petrographic analysis of the carbonate-dominated facies in sequence 3 has delimited nineteen platformal facies representing lagoonal, barrier and shoal, reefal and non-reefal mid-shelf depositional environments. These facies are organized into high-frequency depositional cycles that record the interplay between eustasy, tectonism and sediment supply. In order to facilitate their regional analysis, cycles were grouped into five idealized cycles. From proximal to distal, these cycles include: Sandstone-Grainstone; Grainstone-Palaeoaplysinid; Packstone-Phylloid; Wackestone; and Anhydrite cycles. These high-frequency cycles are grouped into a Pre-, Syn- and Post-evaporite cyclic assemblages, each of which possess an unique stacking pattern. The Pre-evaporite Assemblage comprises 9 cycles characterized by relatively similar thickness and composition. High-frequency cyclicity within this assemblage was controlled by glacio-eustatic oscillations with only local tectonic influence. (Abstract shortened by UMI.)

The Centre Hill complex is part of the mafic to ultramafic Munro Lake sill that occurs within the Stoughton-Roquemaure Group of the Abitibi Subprovince. The complex is approximately 450 m thick and consists of alternating layers of peridotite and clinopyroxenite overlain by 250 m of gabbroic rocks. Two distinct occurrences of cyclic layering are observed: (1) cyclic units of peridotite and clinopyroxenite in the bottom half of the intrusion; and (2) cyclic units of branching-textured gabbro (BTG) and clotted-textured gabbro (CTG) characteristic of the upper layer of gabbro. The upper part of the gabbro is characterized by the presence of spectacular branching crystals that extend away from the upper contact. The primary composition of the branches is interpreted to have been that of Fe-rich olivine based on the actual secondary assemblage. From petrological observations and geochemical data, it is suggested that the branching olivine crystals grew within a crystal-liquid mush in the later stages of fractionation. Two models based on their appearance within the petrogenetic sequence are proposed: (1) the branching olivine crystals grew from the residual melt of the last batch of magma only; or (2) the branching olivine crystallized in the later stages of each cyclic event. The branching textures are truly fractal objects as they are self-similar over a large range of scale. They consistently yield fractal dimensions approximating 1.6. The branching morphologies were qualitatively and quantitatively simulated on the computer using a variation of the Witten-Sander diffusion limited aggregation (DLA) algorithm. From the simulations, it is established that the growth of branching crystals was limited by diffusion of molecules to the crystal-liquid interface, and that the resulting morphology was controlled by two opposing phenomena: (1) the random aggregation of growth molecules along the crystal periphery without relocation; and (2) the systematic arrangement of molecules onto the growing interface according to the internal crystal structure of the mineral. (Abstract shortened by UMI.)

The Chancellor succession accumulated in a deep-water trough bordering a wide, epeiric shelf during Middle and Late Cambrian time. The Chancellor is divisible into seven major lithostratigraphic units, which are correlative with an eastern shelf assemblage comprising eight cabonate and siliciclastic formations. The deep-water carbonate and siliciclastic sediments in the Chancellor are divisible into five basic lithofacies, each of which has several variants due to a variety of depositional and diagenetic factors. Sediments in the argillite lithofacies were deposited by dilute, muddy and silty turbidity currents and hemipelagic settling. The ribbon calcilutite lithofacies was probably deposited in a similar manner, but owes its final appearance to diagenetic enhancement of rhythmic, primary variations in sediment composition. Both of these lithofacies contain a variety of synsedimentary deformation structures indicative of slope instability. The ribbon calcisiltite lithofacies is composed of interbedded silty carbonate and terrigenous mud turbidites. The calcarenite lithofacies is the product of high-concentration turbidity flows. It locally occupies large, channel-like features ("megachannels"), which are inferred to be slide scars incised into the upper slope. Most of the sediments assigned to the conglomerate lithofacies show evidence of matrix strength, and were laid down by debris flows. This lithofacies includes spectacular megaconglomerates containing Epiphyton boundstone blocks up to 50 m in maximum dimension. Periplatform talus blocks of similar size are scattered throughout the Chancellor. During most of Chancellor time, silt- and sand-sized material either bypassed the upper slope or was confined to the shelf. The high proportion of carbonate and siliciclastic turbidites in the Duchesnay and Oke units (middle Chancellor) is a direct reflection of an abrupt, regressive shift in the position of the cratonal shoreline. Spectacular cross-strike exposures have revealed that the Eldon-Pika margin and adjoining upper slope strata (Tokumm and Vermilion sub-units) are traversed by at least three megatruncation surfaces. (Abstract shortened by UMI.)

The Upper Carboniferous Canyon Fiord Formation is genetically related to continental rifting during the early history of Sverdrup Basin. The basal part of the formation, on southwestern Ellesmere Island, has been subdivided into five distinct facies assemblages: (i) a lower sandstone assemblage, deposited in the floodplain environment of high sinuosity streams, and locally in lacustrine and paludal environments; (ii) a conglomerate assemblage, deposited in the alluvial fan to proximal braided stream environment; (iii) an upper sandstone assemblage, deposited in braided stream and coastal plain environments; (iv) an evaporite assemblage, deposited in a local coastal playa and hypersaline lagoon; and (v) a limestone assemblage, deposited in restricted to relatively open, shallow marine environments. These assemblages are exposed within two N-S-oriented outcrop belts, informally called the Trold Fiord belt and the Blind Fiord belt. The outcrop belts are separated by a N-S oblique strike-slip fault of Tertiary age, and are associated with two distinct, Late Carboniferous half-grabens of opposite polarity: (i) the Trold Fiord Depression, situated in the northeastern part of the study area; and (ii) the Blind Fiord Depression, situated in the southwestern part of the study area. The characteristics of the Trold Fiord and Blind Fiord basin-fill successions indicate that sedimentation was controlled by at least two tectono-sedimentary episodes (TSE-1 and TSE-2). (Abstract shortened by UMI.)

Simberi Island is an eroded Pliocene alkaline volcano, the oldest in the Pliocene to Holocene Tabar-Lihir-Tanga-Feni (TLTF) island arc. These islands are derived from partial melting of subduction-modified mantle at $>$60 km depth along extensional, pull-apart structures. Explosive volcanism has brought samples of the mantle wedge to the surface. Within these samples are sulphate-, carbonate-, hydrous-, alkali-rich aluminosilicate glasses which represent quenched slab-derived magmas (SCHARM). SCHARM reacts with mantle peridotite to create a vertically zoned mantle wedge consisting of phlogopite-clinopyroxenite at P $>$ 30 kbar and amphibole-clinopyroxenite at 21 to 30 kbar at 930-1080$\sp\circ$C. Metasomatism of the mantle wedge by SCHARM controls the mineralogical, chemical and isotopic composition of TLTF arc volcanics. The presence of sulphate within SCHARM indicates a high intrinsic oxygen fugacity of FMQ + 4. Oxidative metasomatism of the mantle wedge by SCHARM is responsible for high $\rm Fe\sb2O\sb3$/FeO ratios in the lavas, the early appearance of magnetite on the liquidus and the crystallization of a sulphate-bearing feldspathoidal mineral (ha uyne) in the TLTF lavas. Titanium depletion in the rocks of the TLTF arc is accounted for by the low initial solubility of Ti in SCHARM, coupled with the strong partitioning of Ti into phlogopite at high fo$\sb2.$ Enhanced solubility of sulphur in high fO$\sb2$ melts, caused destabilization of mantle sulfides and concomitant enrichment of chalcophile Au and Cu in volatile-rich, mantle-derived melts, and may be a significant factor in the development of volcanic-hosted Au-Cu deposits in the arc. Enrichments of large ion lithophile elements and rare-earth element in basanites and alkali basalts are also due to SCHARM contamination. Negative Ce and positive Eu anomalies in Simberi basalts are produced by partial melting of feldspathic minerals in subducted, seawater altered mid-ocean ridge basalt (MORB), at the basalt-eclogite transition zone in the mantle. Eutectic melting constraints indicate that SCHARM could be derived during the melting of scapolite, produced by prograde metamorphic reactions between MORB plagioclase and low temperature secondary minerals (calcite, gypsum) in the subducting slab. Metasomatic replacement of forsteritic olivine $\rm(\delta\sp O=5\perthous)$ by high $\rm\delta\sp O$ SCHARM produces $\sp $O-enriched sodian diopside and magnetite $\rm(\delta\sp O$ = 6.3-6.8$\perthous)$ in Simberi basanites. Isotopic disequilibrium exists because of the short 6 Ma) residence time of SCHARM in the mantle.

The Mooshla intrusion is an elliptical body, 4.0 x 1.5 km and is hosted by the Blake River Group, a fault bounded sequence of bi-modal volcanic and volcaniclastic rocks. The intrusion is calc-alkaline in affinity and comprises four distinct units; (1) cumulate gabbros, (2) quartz diorites, (3) tonalites, and (4) leucotonalites. The cumulate gabbros are composed of two textural facies; (1) mesocumulates and (2) a layered sequence. Textural and geochemical evidence suggests that the leucotonalite is the hydrothermally altered and sheared equivalent of the tonalite. The intrusion records four generations of structures; D$\sb1$, D$\sb2$, D$\sb3$, and D$\sb4$. D$\sb1$ produced an E-W striking foliation, S$\sb1$, that dips moderately to the south and is localized to the core of the intrusion. D$\sb2$ represents a period of subhorizontal N-S compression and is the principal deformation event. It is responsible for an $\approx$E-W trending, regionally penetrative foliation, S$\sb2$, that dips steeply to the south and onto which most geological objects are flattened. Both D$\sb3$ and D$\sb4$ are reflected by predominantly brittle structures related to dominantly E-W directed horizontal shortening. The Mooshla intrusion can be subdivided into three structural domains defined by which foliation they contain and the nature and frequency of the high strain zones that they host. (Abstract shortened by UMI.)

Fracture propagation in rock often produces complex patterns, such as the branching patterns of fracture networks, or the irregular radiating patterns on fracture surfaces. These patterns often appear complex because they are unpredictable in detail, yet predictable in the sense that smaller pieces of the pattern, when suitably enlarged, are statistically similar to larger pieces of the pattern. This property of statistical self-similarity can be quantified using fractal geometry. The fractal nature of rock fracture patterns is related to lithological properties and to the dynamics of the fracturing processes. Joint surfaces in homogeneous rocks display rough radiating ridges. A "plumose joint" surface was analyzed using the slit island method and found to have a fractal dimension (D$\sb{\rm f}$) of 2.24 $\pm$.14 (95%). Surfaces with similar fractal dimensions (2.2-2.5) are produced by a three-dimensional computer simulation of jointing. In the simulation, randomly-distributed defects cause local mis-orientations of the stress field and local deflection of the propagating fracture front. After passing through the defect the joint surface is re-oriented relative to remote stresses, and a planar radial fracture segment (i.e. inclusion hackle) is formed. Collectively, the numerous inclusion hackle form the plumose surface pattern. For the simulation results, D$\sb{\rm f}$ increases (i.e. the surface gets rougher) in proportion to the log of the defect density. The simulation also demonstrates a complex relationship between D$\sb{\rm f}$ of the propagating fracture front and D$\sb{\rm f}$ of the fracture surface. Shatter cones are conical fracture surfaces produced during high energy events such as meteorite impact and nuclear explosion. These fractures also display radiating surface features. Using a modified version of the slit island method, the fractal dimension of a shatter cone surface in limestone is estimated to be 2.24 $\pm$ 0.09. The observation of shingled convex fracture surfaces within the conical envelope surrounding the shatter cone surface is demonstrated to support the genetic model of Johnson and Talbot (1964). Striations on these fracture surfaces are reinterpreted as micro-fracture intersections. The measured fractal dimensions of the joint and shatter cone surfaces (i.e 2.24) are within the range reported for most fracture surfaces in metals (i.e. 2.1 $\sim$ 2.3).

Wollaston Peninsula and most of southern Victoria Island comprise Palaeozoic carbonate lowlands, scarps, and tableland situated between rises and arches of underlying Precambrian sedimentary and igneous rocks. Quaternary sediments are hummocky, thick and ice-cored near escarpments where ice flow resistance, thrusting and meltwater concentrated glacial debris; thinner, streamlined drift occurs in lowlands. Quaternary sediments are mainly Late Wisconsinan in age. Glacial sediments predominate but surficial raised marine and periglacial sediments are noted. Fluvial modification of the landscape is minor. Many of the spectacular glacial landforms on Wollaston Peninsula are streamlined and indicate formation under thick, warm-based (i.e. free subglacial water) glaciers. A set of distinctive landforms, including ground moraine (with small moraines and marginal channels), hummocky moraine, lateral moraines, and streamlined forms, relates to varying flow conditions within one major glacial advance. Stratified drift within moraines indicates the importance of glaciofluvial processes in addition to ice action. Collectively, these landforms record ice-marginal retreat, marginal stagnation following compressional flow, surging, flooding and regional stagnation during deglaciation. Freeze-on and ice stagnation trapped extensive bodies of drift-rich ice in zones of hummocky moraine. Arborescent networks of narrow eskers record subglacial meltwater drainage beneath major ice lobes and long broad eskers record subaerial deposition by meltwater of mainly supraglacial derivation. Late glacial events are dated relative to the incursion of the sea during deglaciation of northwest areas of Wollaston Peninsula by about 12 000 BP. Active ice-marginal conditions existed just before 10 000 BP, during formation of the large Colville moraines. Ice downwasted in the area causing glacier thinning. Prominent ground-ice features include pingos, thermokarst scars, and debris-flow lobes. Ground ice occurs as massive icy bodies, ice-wedge ice, and buried pingo ice. Based on its setting in hummocky moraine, its stratigraphy, debris content, and isotopic composition, the massive ice is likely buried glacial ice. Landscape modification by thermokarst erosion has produced ubiquitous diamictons similar to till, and landforms similar to glacial forms. Thick ground ice bodies exist only above marine limit and the limits of streamlined landforms because permafrost degradation occurred below these limits. Widespread thaw slumps and large-scale thermal contraction cracks also indicate ice-cored terrain.

The Upper Ordovician to Lower Devonian platform in the Canadian Arctic twice evolved from a ramp to a rimmed shelf profile. Platform backstepping occurred in the fastigatus, acuminatus, cyphus?, sakmaricus (in North Greenland only) and linearis graptolite zones. Two major phases of pinnacle reef development followed platform backstepping, the first beginning in the lower Llandovery (cyphus Zone) and the second in the Ludlow (linearis Zone). Pinnacles of the first phase are uncommon, occur in the vicinity of Baumann Fiord, and show a vertical succession of lime mudstone, poorly exposed microbial carbonate, and coralgal biolithite, representing upward shallowing. The last named lithofacies is newly interpreted as representing a high-energy, wave-stressed environment that excluded stromatoporoid growth but favoured a sparse skeletal metazoan fauna, thickly encrusted by microbes. Paleo-surface area of these structures was apparently important for the accumulation of extensive ooids, which are associated with the upper parts of some pinnacle reefs. Three large mud buildups on central Ellesmere Island were established on the shelf margin subsequent to Upper Ordovician (fastigatus Zone) platform drowning. These structures show a vertical lithofacies succession: bioturbated lime mudstone is overlain by microbial carbonate then by mudstone-rich stromatoporoid floatstone and bindstone. The succession records overall upward shallowing. The olive green shale unit, well exposed in the vicinity of Trold Fiord, is an areally extensive and mappable middle Ludlow unit of the Cape Phillips Formation that postdates diachronous, middle Ludlow platform backstepping in the vicinity of Baumann Fiord. After backstepping, condensed sequences occurred over paleotopographic highs and expanded sections over lows, and a subsequent second major phase of platform rimming occurred. Stratigraphy known in the southern Arctic Islands is generally applicable to northeastern Ellesmere Island, but local lithological variations occur. The upper part of the Allen Bay Formation at Darling Peninsula, in particular, is unusually thick, and subtidal, perhaps resulting from greater subsidence, related to lithospheric flexure and deep marine clastic sedimentation that drowned the contiguous platform on North Greenland. Other formations recognized in this area include the Cape Storm, Douro, and Goose Fiord formations, although these, too, show minor lithological differences from type sequences. A thick grey siltstone unit in the vicinity of Bay and Vesle fiords is suggested to be a distal facies of the Red Canyon River Formation. This sequence is a progradational clastic wedge that likely represents the first, largest phase of the tripartite Caledonian Inglefield Uplift which profoundly affected carbonate deposition in the areas of southern and central Ellesmere Island during the late Silurian and early Devonian time. The base of this unit is diachronous and likely late Silurian in age. (Abstract shortened by UMI.)