Dissertations / Theses on the topic 'Intermontane'

The purpose of this study is to develop a terrain evaluation system for road corridor selection applicable to the intermontane basins in northern Thailand. The first stage involves database construction of the terrain factors which have a direct effect on construction costs. These factors are land cover, topography and landforms, surficial geology, soil strength, topsoil removal, difficulty of excavation, embankment height, construction materials, and drainage characteristics. Remote sensing and terrain evaluation techniques, field investigations and geotechnical laboratory tests are used to prepare maps of these terrain factors. The resulting maps are converted into digital database form as map layers by using Geographical Resources Analysis Support System (GRASS)--a raster-based Geographic Information System (GIS).<br>These factors are incorporated into cost models. These are constructed using local engineering cost assessments which control the selection and specification of terrain factors. Under the GRASS environment the digital map layers of different terrain attributes are converted, based on the cost models, into cost surfaces (cost per unit area). The cost surfaces are subsequently combined into an integrated terrain-cost model.<br>With different assigned end points and cost models, the applications of the single theme cost surfaces and the integrated terrain-cost models to least-cost route selection are provided. An existing road network can be incorporated in these applications. The quality and benefits of the database and system developed related to terrain conditions, data capture by remote sensing, GIS manipulation and modelling, and cost modelling are discussed.

The Atnarko complex located in west-central British Columbia comprises pre-Early Jurassic metavolcanic and metasedimentary rocks, termed the Atnarko assemblage, which is structurally interleaved with Late Triassic to Early Cretaceous orthogneiss. The Atnarko assemblage correlates with continental margin assemblages found within the Coast plutonic complex. Tectonic interaction between the Insular and Intermontane superterranes resulted in several phases of deformation including; 1) poorly preserved Jurassic deformation, 2) Early to mid-Cretaceous, southwest to west directed, compression, 3) mid-Cretaceous, north to northeast directed, compression, 4) mid- to Late Cretaceous dextral and sinistral ductile/brittle shearing, and 5) post latest Cretaceous brittle faulting. Peak metamorphism coincides with generation of migmatite in the Early Cretaceous (~117-115 Ma) and is contemporaneous with penetrative ductile fabrics. The Atnarko complex had cooled below 350°C by the Late. Comparison of the Atnarko complex to equivalent portions of the orogen along strike, indicates a post mid-Cretaceous change in structural style. To the northwest the orogen records continued southwest-directed compression which dominates the deformation style; while to the southeast large dextral strike-slip faults dominate. Relative plate motions between ca. 70-60 Ma indicate that dextral transpression occurred between the Kula and North American plates. Strain during this transpressive deformation was partitioned into compressive and translational regions. The Atnarko complex area is situated at the transition between translation and compression. The conditions of the lower and middle crust within the orogen were established by how strain was partitioned across the orogen. The distributed strain also shaped how the orogen responded to Tertiary extension. Continued compression to the northwest of the Atnarko complex led to increased crustal thickness and partial melting of lower and middle crust in the Tertiary. Conversely, the cessation of compression in the southeast lead to a more stable (i.e. cooler) crustal lithosphere. A change in relative plate motions in the early Tertiary triggered full-scale, orogen-perpendicular, collapse in the northwest facilitated by decoupling between the middle and lower crusts along thermally weakened layers. Localized orogen-parallel extension occurred in the southeast which was kinematically linked to large dextral strike-slip faults where the upper crust remained coupled to the middle and lower crust.

The Redfern Complex is a klippe of a dismembered, metamorphosed ophiolite resting on top of the crystalline Snowshoe Group in east-central British Columbia. The Snowshoe Group belongs to the Barkerville terrane of the Omineca Crystalline Belt while the Redfern Complex, which is structurally overlain by the Triassic black phyllite, comprises the basement to Quesnel terrane rocks of the Intermontane Belt. The contiguous boundary between the two belts lies west of the Redfern Complex and is marked by the Crooked Amphibolite, a thin, highly sheared mafic amphibolite with blocks of ultramafic rock near its base. The Redfern Complex and Crooked Amphibolite are correlative assemblages evidenced by similiarities in lithology, whole rock and mineral chemistry, and structural position. Both assemblages are composed of variable amounts of hornblende-epidote-palgioclase amphibolite, dunites, cumulate layered peridotite, and serpentinite. Chemically the rocks are subalkaline, tholeiitic basalts or gabbros and depleted peridotite with relict forsteritic olivine (Fo₈₃ and Fo[sub 87-90.7]), chromian diopside, and chromite spinel. Ultramafic rocks from both assemblages show evidence of plastic deformation under mantle conditions including disolcation glide on the high temperature (010): [100] slip system and glide climb in olivine, plus dynamic recrystallization and dynamic recovery. Although the structural succession of lithologies is best defined at the locality of the Redfern Complex, variably complete structural successions across the Crooked Amphibolite were observed which indicate that the two units occupy the same structural position on top of the Hadrynian to Paleozoic metasedimentary Snowshoe Group and that both units are structurally overlain by the Triassic black phyllite. The two assemblages differ in intensity of metamorphism and degree of hydration alteration related to their relative structural positions and their size and permiability. While the Crooked Amphibolite bears the chlorite-zone assemblage actinolite + chlorite + plagioclase and related ultramafic rocks are dominantly completely serpentinized, the Redfern amphibolite metamorphic assemblage of hornblende + albite + epidote belongs to the albite-epidote amphibolite facies. In addition the large, coherent Redfern peridotite body shows evidence of complete serpentinization only at its margins and also bears an amphibolite facies assemblage of tremolite + olivine + chlorite + talc. Thus the Redfern Complex experienced more intense metamorphism because it occupied a deeper structural level than the Crooked Amphibolite. The local and regional setting of the Redfern Complex reflects a complex geologic history of multiple defomration episodes and syntectonic, locally intense metamorphism related to the emplacement of the Complex onto the Snowshoe Group along the east-vergent Redfern thrust. Prior to emplecement, the Snowshoe Group underwent one enigmatic phase of deformation and metamorphism. The intrusion of the felsic Redfern orthogneiss which has a poorly constrained U-Pb age of Devono-Mississippian may be related to this deformation. A second orthogneiss which intrudes the Redfern amphibolite and contains ultramafic xenoliths probably intruded during or soon after emplacement. Tight, east-vergent folds and a pervasive second foliation developed in the Snowshoe Group while tight folds and a pervasive foliation developed in the Redfern amphibolite and Triassic black phyllite during emplacement. Microfracturing and grain sliding predominantly on the margins of the Redfern peridotite are the only structures developed during emplacement. Metamorphism peaked after emplacement stresses had relaxed, producing sillimanite in the Snowshoe metapelites, albite-epidote amphibolite assemblages in mafic lithologies, and possibly only kyanite in the black phyllites. Post-emplacement deformation accompanied sustained but decreased temperatures of metamorphism. Large-scale, west-vergent, overturned to the east buckles fold the Redfern thrust and refold earlier structures and produced the current map patterns and distribution of foliation. Kinked metamorphic porphyroblasts and an S₂ crenulation cleavage overgrown by staurolite in the Triassic black phyllite indicate that intense deformation and fluid enhanced retrograde metamorphic reactions were localised in a structurally lower "pocket" of this unit in the core of a post-emplacement synform on the east side of the map area.<br>Science, Faculty of<br>Earth, Ocean and Atmospheric Sciences, Department of<br>Graduate

The Tatla Lake Metamorphic Complex (TLMC) underlies 1000 km² on the western side of the Intermontane Belt (1MB) northeast of the Yalakom fault Three fault-bounded lithotectonic assemblages are recognized in the area studied: an amphibolite grade gneissic and migmatitic core, structurally overlain by a 1 to 2.5 + km-thick zone of amphibolite and greenschist grade mylonite and ductilely sheared metamorphic rocks, the ductilely sheared assemblage (DSA), which is in turn structurally overlain by weakly deformed to unstrained subgreenschist grade rocks of the upper plate which flank the TLMC on three sides. Structures in the gneissic core include a gneissic foliation and schistosity (Sic), which has been deformed by west to northwest-trending tight to isoclinal folds (F2c). Tectonic fabrics observed throughout the DSA which formed during Ds deformation include a gently dipping mylonitic foliation (Ss), containing a mineral elongation (stretching) lineation (Ls) which trends towards 280° ± 20°. Minor folds of variable trend (Fs), almost exclusively confined to DSA metasedimentary rocks, are interpreted as coeval with ductile shear. Vergence of these folds defines movement sense and direction of top towards 290° ± 20°. Kinematic indicators from DSA rocks which have not been deformed by syn-ductile shear folds indicate a top-to-the-west sense of shear while those deformed by Fs folds yield conflicting results, with a top-to-the-west sense predominating. The entire lower plate comprising the TLMC has been deformed by broad, upright, west to west-northwest trending, shallowly plunging map-scale folds (F3) during D3, which deform Sic and Ss surfaces. The steeply dipping, northwest-trending Yalakom fault truncates all units and structures of the TLMC. Gently to moderately dipping normal faults of Ds and post-D3 relative age are the southern and eastern boundaries between DSA upper plate rocks and 1MB lower plate rocks. U-Pb zircon dates from igneous arid meta- igneous rocks from the lower plate range from Late Jurassic (157 Ma) through Eocene (47 Ma). These dates bracket the timing of Cretaceous (107 Ma to 79 Ma, in the core) and Eocene (55 Ma to 47 Ma, in the DSA) deformation and metamorphism in the lower plate. Biotite and hornblende K-Ai dates of 53.4 Ma to 45.6 Ma for lower plate rocks are in sharp contrast to Jurassic dates from nearby upper plate rocks; they record the uplift and cooling of the TLMC. Whole rock initial ⁸⁷Sr/⁸⁶Sr ratios (and for most samples present-day values) of less ≤0.704 have been determined for igneous and meta-igneous rocks of the TLMC; such values are typical of magmatic arc rocks of the 1MB and Coast Plutonic Complex of B.C. Whole rock major and trace element chemistry of lower plate igneous and meta-igneous rocks indicate sub-alkaline, calcalkaline, volcanic arc affinities. Garnet-biotite temperatures (interpreted as Eocene in age), from pelitic schist in the southern part of the DSA increase from about 400 ± 50 to 650 ± 50 C with increasing structural depth. A GT-BI-QZ-Al₂SiO₅ pressure of 8 ± 3 kb has been calculated for one of these samples. A T-P of 650 ± 50 C and 5.3 ± 3 kb, calculated from inclusions and garnet cores in a small pelitic pendant in the northwest part of the DSA, reflects conditions during intrusion of the surrounding 71 ± 3 Ma igneous body. A pressure of 7.2 ± 1.4 kb, based on the total Al in hornblende, has been calculated for this body. Cretaceous ductile deformation in the gneissic core may be related to folding and thrusting which occured in high level rocks to the west and east of the field area. During Early Eocene time (55-47 Ma) the TLMC acquired the characteristics of a Cordilleran metamorphic core complex. Mylonites of the DSA were emplaced by faulting beneath weakly deformed, low metamorphic grade rocks of the upper plate. Synchronously, metamorphic rocks of the gneissic and migmatitic core of the TLMC were moved to higher crustal levels along the footwall of the DSA normal ductile shear zone. The formation of F3 folds and final uplift of the TLMC (47-35 Ma) is postulated to be the consequence of transpression related to later Eocene dextral motion along the Yalakom fault The TLMC has structural style and timing of deformation similar to metamorphic core complexes in southeastern B.C. Local and regional evidence is consistent with the formation of the TLMC in a regional extensional setting within a vigorous magmatic arc.<br>Science, Faculty of<br>Earth, Ocean and Atmospheric Sciences, Department of<br>Graduate

The Ingenika Range forms part of a large zone of structural divergence that roughly coincides with the boundary between North America and Superterrane I. Contrasting tectonic histories from the Intermontane, Omineca and Foreland Belts at the latitude of the thesis area are consistent with a collisional model involving tectonic wedging, delamination and large-scale backthrusting.<br>The Upper Proterozoic Ingenika Group in the Ingenika Range has undergone a progressive deformational history involving pre-, syn-, and post-metamorpic structures. During the Middle Jurassic regional structural vergence changed from northeast- to southwest-directed folds and faults. Regional metamorphism reached amphibolite grade and was synchronous with west-vergent deformation. Minor structures in the study area suggest that the Swannell fault was an east-dipping thrust fault that emplaced North American strata over allochthonous rocks of Quesnellia. The Swannell fault was probably also active during the Middle Jurassic and may have acted as the structural discontinuity between a backthrusted crustal flake and an underlying, eastward moving wedge.

This study presents 48 new U-Pb and 35 new K-Ar dates for magmatic rocks of the Coast Plutonic Complex (CPC) between 53°N and 54°N. The eastern flank of the CPC is underlain by the Gamsby Complex, an early Late Jurassic (160-155 Ma) magmatic, metamorphic and ductile compressional belt superimposed on Early (197-190 Ma) and Middle (178 Ma) Jurassic magmatic rocks of the Intermontane superterrane. The Gamsby Complex was uplifted and cooled in latest Jurassic-Early Cretaceous time (145-132 Ma). Small Early Cretaceous intrusions (132-120 Ma) in the Gamsby Complex are clearly post-kinematic, and no evidence was found for a major middle Cretaceous orogenic episode in the eastern flank of the CPC. The Central Gneiss Complex in the core of the CPC contains large Late Cretaceous (80 Ma) and Eocene plutons that are commonly sill-like. The Central Gneiss Complex gives Eocene K-Ar dates, and is proposed to be an Eocene (51 Ma) metamorphic core complex, which underlies the eastern flank of the CPC beneath a gently to moderately dipping ductile extenslonal shear zone; the tectonic boundary with the western flank of the CPC is gently to steeply dipping. Biotites from positions structurally low in the Gamsby Complex give K-Ar dates (51-50 Ma) which appear to reflect resetting above a rapidly rising hot Central Gneiss Complex. The Eocene extenslonal boundary between the Central Gneiss Complex and the Gamsby Complex was disrupted by steep brittle faults of the Sandifer Lake fault zone, which localize Oligocene (33 Ma) lamprophyre dyke swarms. The west flank of the CPC contains three major tectonic belts, from west to east: 1) The Banks Island belt, composed of large, 160-155 Ma pre-, syn-, and post-kinematic plutons intrusive Into strata of the Insular superterrane; this belt cooled in latest Late Jurassic time (148-143 Ma). 2) The McCauley Island belt, containing Early Cretaceous (131-123 Ma) plutons which cooled in middle Cretaceous time (109-97 Ma). 3) The Ecstall belt, representing a major middle Cretaceous (110-94 Ma) magmatic pulse; this belt cooled by Late Cretaceous time (67 Ma). The new geochronometric results are integrated into a regional tectonic model in which all Jurassic-Eocene components of the CPC and adjacent belts are related to changing patterns of east-dipping subduction beneath a single allochthonous Alexander-Wrangellia-Stikinia (AWS) megaterrane, which was emplaced against the western margin of North America in Middle Jurassic time, closing off the Cache Creek-Bridge River ocean. Following accretion of the AWS megaterrane an early Late Jurassic magmatic arc and associated structures were built mainly along the new outboard margin of North America, but they also overprinted the Cache Creek suture and eastern terranes, including rocks of North American affinity. Early in its history the Washington to Alaska central part of the Late Jurassic arc was rifted (and perhaps displaced longitudinally as well) causing the formation of intra-arc flysch basins and in effect breaking up the AWS megaterrane into two fragments corresponding to the Insular and Intermontane superterranes. These were subsequently overprinted by magmatic belts that define the present CPC. A major middle Cretaceous magmatic pulsewas accompanied by widespread crustal shortening across the CPC, and Eocene magmatism was accompanied by crustal extension, which may have continued into late Tertiary time. Successive episodes are presumably related to changes in relative plate motions and velocities between the North American continent and Pacific oceanic lithosphere, within a primary setting of long-lived, obliquely east-dipping subduction beneath a single terrane. This intra-terrane model for the evolution of the CPC differs from the superterrane collision model of Monger et al. (1982), and is compatible with the scenario suggested by Brew and Ford (1983), who first suggested that the CPC may be an intra-terrane feature. There are no sutures in the CPC, and the CPC is not the result of a collision between discrete superterranes.<br>Science, Faculty of<br>Earth, Ocean and Atmospheric Sciences, Department of<br>Graduate

L’évolution du bassin du Golfe de Guayaquil-Tumbes (BGGT) est contrôlée par une extension parallèle à la fosse qui résulte de l’échappement du Bloc Nord Andin (BNA) vers le nord. Cette extension de direction N-S est accommodée le long du plateau continental par une série de failles normales à faible pendage (les détachements de Posorja, Jambelí et Tumbes) pendant le Pléistocène inférieur. Au contraire, le long de la pente continentale, la subsidence commence au Miocène et est liée à un régime de subduction érosion. Ces deux régimes extensifs sont limités par un système de transfer placé le long de la zone de rupture de la pente continentale (i. E. Le système de failles de Domito et la faille du Banco Peru). Le détachement de Tumbes correspond à la faille principale qui contrôle l’évolution du BGGT. Il se prolonge probablement vers les structures pouvant correspondre à la frontière est du BNA le long des Andes équatoriens, là où la formation des bassins intramontagneux est également liée à l’échappement du BNA. Dans ce contexte les bassins de Santa Isabel et le BGGT semblent avoir évolués avec un scénario d’échappement tectonique similaire<br>The Gulf of Guayaquil-Tumbes basin (GGTB) evolution is controlled by the trench-parallel extension that results from the North Andean block (NAB) northward drifting. This N-S directed extension is accommodated along the shelf by low-angle detachment normal faults (the Posorja, Jambelí and Tumbes detachment systems) during Pleistocene. In contrast, along the continental margin E-W directed subsidence began in Miocene times produced by a subduction erosion regime working at depth. Both regimes are limited by a major transfer system roughly located at the continental margin shelf break extending from the Domito faults system to the Banco Peru fault. The Tumbes detachment system corresponds to the master fault of basin evolution. It probably connects with the continental structures assumed to define part of the eastern frontier of the NAB, where intermontane basin formation along the central Ecuadorian Andes is also related to NAB drifting. In this discrete basin formation setting the Santa Isabel basin and the GGTB seem to have evolved along the same escape tectonic scenario

The intermontane Ipswich Basin, which is situated 30km south-west of Brisbane, contains coal measures formed in the Late Triassic Epoch following a barren non-depositional period. Coal, tuff, and basalt were deposited along with fluvial dominated sediments. The Ipswich Coal Measures mark the resumption of deposition in eastern Australia after the coal hiatus associated with a series of intense tectonic activity in Gondwanaland during the Permo-Triassic interval. A transtensional tectonic movement at the end of the Middle Triassic deformed the Toogalawah Group before extension led to the formation of the Carnian Ipswich Coal Measures in the east. The Ipswich Coal Measures comprise the Brassall and Kholo Subgroups. The Blackstone Formation, which forms the upper unit of the Brassall Subgroup, contains seven major coal seams. The lower unit of the Brassall Subgroup, the Tivoli Formation, consists of sixteen stratigraphically significant coal seams. The typical thickness of the Blackstone Formation is 240m and the Tivoli Formation is about 500m. The coal seams of the Ipswich Basin differ considerably from those of other continental Triassic basins. However, the coal geology has previously attracted little academic attention and the remaining exposures of the Ipswich coalfield are rapidly disappearing now that mining has ceased. The primary aim of this project was to study the patterns of coal sedimentation and the response of coal seam characteristics to changing depositional environments. The coal accumulated as a peat-mire in an alluvial plain with meandering channel systems. Two types of peat-mire expansion occurred in the basin. Peat-mire aggradation, which is a replacement of water body by the peatmire, was initiated by tectonic subsidence. This type of peat-mire expansion is known as terrestrialisation. It formed thick but laterally limited coal seams in the basin. Whereas, peat-mire progradation was related to paludification and produced widespread coal accumulation in the basin. The coal seams were separated into three main groups based on the mean seam thickness and aerial distribution of one-meter and four-meter thickness contour intervals. Group 1 seams within the one-meter thickness interval are up to 15,000m2 in area, and seams within the four-meter interval have an aerial extent of up to 10,000m2. Group 1A contains the oldest seam with numerous intraseam clastic bands and shows a very high thickness to area ratio, which indicates high subsidence rates. Group 1B seams have moderately high thickness to area ratios. The lower clastic influx and slower subsidence rates favoured peat-mire aggradation. The Group 1A seam is relatively more widespread in aerial extent than seams from Group 1B. Group 1C seams have low mean thicknesses and small areas, suggesting short-lived peat-mires as a result of high clastic influx. Group 2 seams arebetween 15,000 and 35,000m2 in area within the one-meter interval, and between 5,000 and 10,000m2 within the four-meter interval. They have moderately high area to thickness ratios, indicating that peat-mire expansion occurred due to progressively shallower accommodation and a rising groundwater table. Group 3 seams, which have aerial extents from 35,000 to 45,000m2 within the one-meter thickness contour interval and from 10,000 to 25,000m2 within the four-meter interval, show high aerial extent to thickness ratios. They were deposited in quiet depositional environments that favoured prolonged existence of peat-mires. Group 3 seams are all relatively young whereas most Group 1 seams are relatively old seams. All the major fault systems, F1, F2 and F3, trend northwest-southeast. Apart from the West Ipswich Fault (F3), the F1 and F2 systems are broad Palaeozoic basement structures and thus they may not have had a direct influence on the formation of the much younger coal measures. However, the sedimentation patterns appear to relate to these major fault systems. Depocentres of earlier seams in the Tivoli Formation were restricted to the northern part of the basin, marked by the F1 system. A major depocentre shift occurred before the end of the deposition of the Tivoli Formation as a result of subsidence in the south that conformed to the F2 system configuration. The Blackstone Formation depocentres shifted to the east (Depocentre 1) and west (Depocentre 2) simultaneously. This depocentre shift was associated with the flexural subsidence produced by the rejuvenation of the West Ipswich Fault. Coal accumulation mainly occurred in Depocentre 1. Two types of seam splitting occurred in the Ipswich Basin. Sedimentary splitting or autosedimentation was produced by frequent influx of clastic sediments. The fluvial dominant depositional environments created the random distribution of small seam splits. However, the coincidence of seam splits and depocentres found in some of the seams suggests tectonic splitting. Furthermore, the progressive splitting pattern, which displays seam splits overlapping, was associated with continued basin subsidence. The tectonic splitting pattern is more dominant in the Ipswich Basin. Alternating bright bands shown in the brightness profiles are a result of oscillating water cover in the peat-mire. Moderate groundwater level, which was maintained during the development of the peat, reduced the possibility of salinisation and drowning of the peat swamp. On the other hand, a slow continuous rise of the groundwater table, that kept pace with the vertical growth of peat, prevented excessive oxidation of peat. Ipswich coal is bright due to its high vitrinite content. The cutinite content is also high because the dominant flora was pteridosperms of Dicroidium assemblage containing waxy and thick cuticles. Petrographic study revealed that the depositional environment was telmatic with bog forest formed under ombrotrophic to mesotrophic hydrological conditions. The high preservation of woody or structured macerals such as telovitrinite and semifusinite indicates that coal is autochthonous. The high mineral matter content in coal is possibly due to the frequent influx of clastic and volcanic sediments. The Ipswich Basin is part of a much larger Triassic basin extending to Nymboida in New South Wales. Little is known of the coal as it lacks exposures. It is apparently thin to absent except in places like Ipswich and Nymboida. This study suggests that the dominant control on depocentres of thick coal at Ipswich has been the tectonism. Fluvial incursions and volcanism were superimposed on this.

Amphibian populations are declining globally, and pesticides have been suggested as one of the contributing factors. Field experiments involving ponds immersed in agricultural environments have been observed to have dramatically lower biodiversity and amphibian abundance than ponds located in non-agricultural settings. There has been much work involving in situ pond experiments, and a plethora of laboratory pesticide experiments often involving test concentrations much higher than those observed in the field. To determine which pesticides impact amphibian embryo survivorship and tadpole development, three insecticides currently used in British Columbia were tested at their detected field concentrations in a laboratory environment. The commercial formulations of endosulfan, azinphos-methyl and diazinon were tested alone and in combination. Embryos of the Great Basin Spadefoot (Spea intermontana and Pacific Treefrog (Pseudacris regilla) were collected from reference sites in the South Okanagan of BC, and transported to a federal government laboratory facility in North Vancouver, BC. Here, 8-day LC20 experiments were conducted on the young embryos and young tadpoles with the following toxicological endpoints: acute mortality, behavioral abnormalities, morphological abnormalities and developmental abnormalities. Overall, endosulfan (LC20₈d = 77.1 ng/L) was the most toxic pesticide to both species in the tadpole stage, causing acute mortality, behavioral abnormalities and morphological abnormalities. Embryos were observed to be very resilient to the low test concentrations of endosulfan, with the majority of mortalities occurring post-hatch (LC20₈d = 2872.7 ng/L). The second most toxic insecticide was found to be azinphos-methyl (LC20₈d > 50 000 ng/L); and lastly, diazinon was found to be the least toxic (LC20₈d > 175 000 ng/L) to both life stages of amphibians. In addition to acute mortality, several behavioral abnormalities arose in the tadpoles exposed to endosulfan, including extreme agitation in both species of amphibians, tail kinking and melanophore aggregation in P. regilla tadpoles.

The Intermontane Superterrane and Coast Plutonic Complex in southern Yukon Territory are characterized by four episodes of Mesozoic and Cenozoic magmatism which are defined by geological mapping, geochronometry, and whole rock and Sr isotopic geochemistry. Late Triassic to Early Jurassic Klotassin Episode (220-175 Ma), mid-Cretaceous Whitehorse Episode (115-106 Ma), Late Cretaceous Carmacks Episode (85-68 Ma) and Early Tertiary Skukum Episode (61-54 Ma). There was a pronounced magmatic lull between 172-120 Ma. Twenty-two U-Pb, 25 K-Ar dates and greater than 60 strontium isotopic analyses from plutonic and volcanic rocks across the study area are presented to define the timing and nature of magmatic and tectonic events. U-Pb dates are mostly concordant to mildly discordant with minor amounts of Pb-loss-older inherited components are rare. Each magmatic episode is represented by two or more plutonic suites. The Klotassin Episode comprises the pre-accretionary Stikine and Red Ridge suites, the syn-accretionary Aishihik and Long Lake suites and the post-accretionary Bennett and Fourth of July suites. The Stikine suite is the plutonic equivalent to Lewes River Group volcanism, whereas Long Lake granites are coeval with Nordenskiold dacite. The Whitehorse Episode is composed of the Teslin, Whitehorse and Mount Mclntyre suite. The Carmacks Episode is composed of felsic and mafic phases of the Wheaton River suite as well as the Carcross suite. Skukum Episode magmatism includes Nisling Range plutonic suite as well as high level rhyolite plugs that are associated with Skukum Group volcanism. All plutonic suites have characteristics of calc-alkaline, magnetite-series, l-type subduction-related granitoids except those of the Skukum Episode which contain fluorite and have high Rb/Sr ratios (up to 100) and are akin to A-type magmas. Initial 8 7Sr/8 6Sr ratios of all suites are largely transitional (~ 0.7045) and range from 0.7035 to 0.7066. Elevated values reflect local upper crustal contamination from the pericratonic Nisling Terrane Post-accretionary volcanic successions in southwestern Yukon Territory were deposited as part of a continental margin volcanic arc across the amalgamated terranes during Late Mesozoic time. Isotopic dating indicates that volcanism occurred episodically during mid- to Late Cretaceous time at 106, 98, 84 and 81-78 Ma. The mid-Cretaceous (106 Ma) Carbon Hill volcanic rocks comprise a few small occurrences of intermediate to felsic pyroclastic units around a comagmatic pluton. The Montana Mountain volcanic rocks occur in a fault-bounded complex comprising 98 Ma intermediate flows and pyroclastics overlain by felsic flows that are -13 m.y. younger. Late Cretaceous Wheaton River volcanics (81-78 Ma) consist of an extensive succession of basic to intermediate lava flows cut by 70-62 Ma rhyolite dykes and plugs. The ages of these volcanic successions provide maximum age constraints for the epigenetic precious metal deposits they host, and minimum ages for the underlying coal-bearing strata of the Tantalus Formation. Major element geochemistry indicates that all three suites were formed from medium to high-K, calc-alkaline magmas. Initial strontium ratios vary considerably between the suites (0.7041 to 0.7061). Low ratios in the Wheaton River and Montana Mountain suites (-0.7042) indicate derivation from primitive, mantle-derived magmas. Higher initial strontium ratios in the Carbon Hill suite (-0.7052) suggest contamination from ancient continental material-probably from Nisling Terrane metasedimentary rocks. U-Pb zircon dating of granitic cobbles, and paleocurrents in Lower Jurassic Laberge Group conglomerate of the Mesozoic Whitehorse Trough suggest provenance from a western source containing Late Triassic (ca. 215 to 208 Ma) plutons. Small, isotopically unevolved plutons of Late Triassic to earliest Jurassic age that intrude the Lewes River Group volcanic arc rocks along the western margin of the Whitehorse Trough are the likely source. The age dates, the lack of zircon inheritance, and the primitive initial strontium values of the clasts rule out previous suggestions that the clasts were derived from the Early Jurassic Klotassin suite batholiths which intrude Nisling Terrane rocks. The deposition of very coarse Lower Jurassic boulder conglomerate on top of Late Triassic carbonate fades represents a dramatic change in the depositional style of the Whitehorse Trough. Sudden uplift incised a Lower Jurassic erosional disconformity into arc and arc-flanking shelf deposits along the western margin of the Whitehorse Trough. Episodic uplift resulted in paleotopographic relief in the arc sufficient to prograde coarse-grained debris flows into the basin and expose the plutonic roots of the arc throughout Early Jurassic time.

The antelope-brush shrub-steppe of the South Okanagan is small in size yet home to many of the unique and endangered flora and fauna of British Columbia and Canada. More insect species are found in this ecosystem than other grassland ecosystems. Antelope-brush ecosystems are dominated by bunchgrasses, antelope-brush, and a well-developed cryptogam crust, owing to the hot and dry summers of the South Okanagan. Urban and vineyard development are the most immediate threat to this fragile ecosystem, followed by unmanaged livestock grazing. Livestock grazing exposes soil, stunts plant growth, and fragments the cryptogam crust. Less than 9% of the antelope-brush ecosystem is relatively undisturbed and only two small ecological reserves exist. Orthopterans are the most important invertebrate herbivore in North American grasslands and are one of the main biotic influences on grasslands. While Orthopterans assist with biomass turnover and nutrient cycling processes of ecosystem functioning, they may add to the effects of livestock overgrazing. Numerous studies have shown contradictory results of the relationship between grasshopper abundances and grazing pressures. As part of a larger study of the biodiversity and impact of grazing on this threatened ecosystem, this study was conducted to determine how livestock grazing in the intermontane grasslands of the South Okanagan of British Columbia influenced the abundance and species assemblage of Orthopterans. Orthopterans were collected with pitfall traps in ten locations in the antelope-brush ecosystem of the South Okanagan over two years. The study sites were of three different grazing levels: 1) non-grazed; 2) moderately grazed; and 3) heavily grazed. Vegetation data were collected with Daubenmire plots at each site. Twenty-four orthopteran species were captured (seventeen grasshopper species and seven cricket species). All seventeen grasshopper species were previously known to occur in British Columbia, but the taxonomies of four of the cricket species are currently being revised. Grazing did not affect orthopteran species abundance or diversity. Regression analyses showed that the number of orthopteran species and Shannon-Wiener Index values increased with increasing bare soil. The effects of grazing on the vegetation community and structure, and its corresponding effects on the orthopteran species assemblage, are discussed.<br>Science, Faculty of<br>Zoology, Department of<br>Graduate

The evolution and structure of a dendritic peat deposit in the interior lowland of tropical Peninsular Malaysia is investigated as a viable archive of paleoecological and paleoclimatological changes. The project was initiated due to the lack of understanding fundamental processes of intermontane peat accumulating systems mainly because previous studies have focused exclusively on coastal lowland deposits. Peat stratigraphy, mineralogy, organic petrography and geochemistry are some methods utilized in this study. The modern depositional environment of the Tasek Bera Basin includes lowland dipterocarp forest, swamp forest, Cyperaceae/Pandanaceae swamp and open water areas. Widespread peat deposition in the basin started about 5300 years BP, when Holocene climate changes led to the evolution of a wetland system. Peat accumulation progressively expanded by processes of terrestrialization of channels and subbasins and paludification of the riparian part of the lowland forest zone. Stratigraphic facies can be distinguished in the field and combined with the ash yield, which indicates rapid and cyclic changes of frequency and magnitude of runoff events, demonstrating that hydrologic and in turn climate dynamics dictate peat evolution. Although tropical peat deposits are widespread, few classification systems exist that recognize the distinctive characteristics specifically of tropical peats. A three-group field classification (fibric, hemic, sapric) for organic soils based on texture and fiber content is proposed. In addition, a new classification of organic soils based on loss of ignition and carbon content for geological, engineering, agricultural and economical studies of tropical peatlands is developed. Peat is defined as having a loss of ignition of 45 to 100 wt-%, muck 35 to 45 wt-%, organic-rich soils/sediments 20 to 35 wt-%, and mineral soils/sediments 0 to 20 wt-%. Abundant and unique Al-Si bioliths exist in the mire system of Tasek Bera. These Al- and Sihydroxides and the opaline silica from diatoms and sponges represent a repository of Al and Si, which may contribute to mineral transformation, neoformation and alteration processes during coalification of the peat deposits. Most plant-essential nutrients are biocycled within the top 150 cm of the organic deposits causing an upward migration of plant-essential elements, such as Mg, Ca, or P, during mire evolution. Hence, incorrect paleoclimatic and paleodepositional interpretation may result from utilizing geochemical data (e.g. normalization of elements with Al, interpretations of major element data) of tropical peat deposits. With burial, the deposits of Tasek Bera Basin would yield a dendritic sediment pattern of sandstone, shale, carbonaceous shale and low to high ash coal, overlain by carbonaceous shale. Because of the dendritic nature of the basin, coal seams would most likely have a similar pattern as the Carboniferous coal deposits of the Black Warrior Basin in Alabama (USA). The peat deposits of southern Tasek Bera reveal that thick, low-ash, low sulfur peat may originate in narrow tributary valleys with moderately steep flank gradients. The deposits may be favorable precursors to dulling-upward coals, in that they contain high wood and low-ash content at depth and medium wood and slightly increasing ash content in the upper parts.

The fault-bounded Cianzo basin represents a Cenozoic intermontane depocenter between the Puna plateau and Eastern Cordillera of the central Andean fold-thrust belt in northern Argentina. New characterizations of fold-thrust structure, nonmarine sedimentation, and sediment provenance for the shortening-induced Cianzo basin at 23°S help constrain the origin, interconnectedness, and subsequent uplift and exhumation of the basin, which may serve as an analogue for other intermontane hinterland basins in the Andes. Structural mapping of the Cianzo basin reveals SW and NE-plunging synclines within the >6000 m-thick, upsection coarsening Cenozoic clastic succession in the shared footwall of the N-striking, E-directed Cianzo thrust fault and transverse, NE-striking Hornocal fault. Growth stratal relationships within upper Miocene levels of the succession indicate syncontractional sedimentation directly adjacent to the Hornocal fault. Measured stratigraphic sections and clastic sedimentary lithofacies of Cenozoic basin-fill deposits show upsection changes from (1) a distal fluvial system recorded by vi fine-grained, paleosol-rich, heavily bioturbated sandstones and mudstones (Paleocene‒Eocene Santa Bárbara Subgroup, ~400 m), to (2) a braided fluvial system represented by cross-stratified sandstones and interbedded mudstones with 0.3 to 8 m upsection-fining sequences (Upper Eocene–Oligocene Casa Grande Formation, ~1400 m), to (3) a distributary fluvial system in the distal sectors of a distributary fluvial megafan represented by structureless sheetflood sandstones, stratified pebble conglomerates and sandstones, and interbedded overbank mudstones (Miocene Río Grande Formation, ~3300 m), to (4) a proximal alluvial fan system with thick conglomerates interbedded with thin discontinuous sandstone lenses (upper Miocene Pisungo Formation, ~1600 m). New 40Ar/39Ar geochronological results for five interbedded volcanic tuffs indicate distributary fluvial deposition of the uppermost Río Grande Formation from 16.31 ± 0.6 Ma to 9.69 ± 0.05 Ma. Sandstone petrographic results show distinct upsection trends in lithic and feldspar content in the Casa Grande, Río Grande, and Pisungo formations, potentially distinguishing western magmatic arc (Western Cordillera) sediment sources from evolving eastern thrust-belt sources (Puna‒Eastern Cordillera). In addition to growth stratal relationships and 40Ar/39Ar constraints, conglomerate clast compositions reflect distinct lithologic differences, constraining the activation of the Cianzo thrust and coeval movement on the reactivated Hornocal fault. Finally, U-Pb geochronological analyses of sandstone detrital zircon populations in conjunction with paleocurrent data and depositional facies patterns help distinguish localized sources from more distal sources west of the basin, revealing a systematic eastward advance of Eocene to Miocene fold-thrust deformation in the central Andes of northern Argentina.<br>text

Road expansion and increased traffic likely exacerbates barriers to amphibian migration and dispersal. Within British Columbia’s south Okanagan valley there is particular concern that the COSEWIC-listed blotched tiger salamander (Ambystoma mavortium melanostictum) and Great Basin spadefoot (Spea intermontana) are vulnerable to road effects in their annual movements from upland overwintering habitat to lowland breeding areas. My study utilizes a before after control impact approach to assess amphibian movement and population threats across this highway-bisected landscape. Throughout the spring and summer of 2010-2012, fifty two kilometers of roadways (31 km of highway, 21 km of paved backroad) were repeatedly surveyed from the Canada-USA border to north of Oliver, BC; surveys were carried out utilising vehicles and on foot. Along Highway 97, a three kilometer four-lane highway expansion project was constructed through 2010 and open to traffic use in 2011. Adjacent to a floodplain, survey effort was focused throughout this transect for informed roadkill mitigation structure placement and ongoing ecopassage effectiveness monitoring. Automated camera trap monitoring of culverts within highly concentrated amphibian road hotspots during spring and summer 2011 (three culverts) and 2012 (two culverts) resulted in over eight hundred amphibian culvert events observed. Two sample Wilcoxon tests revealed differences between years in amphibian occurrence between 2010 and 2012 (W = 4679.5, p= 0.02), and mortalities among transect areas, with the largest differences between years within the Osoyoos passing lanes transect. Amphibian mortalities within the passing lanes transect were significantly reduced with the implementation of mitigation structures (x̅2010= 13.2 ± 32.5, x̅2011= 4.7 ± 12.8, x̅2012= 2.3 ± 7.3; 2010 vs. 2012: W= 1535.5, p< 0.001). Roadkill mitigation structures proved effective in observed amphibian occurrence of the entire passing lanes stretch as well as at distances 100 m and 200 m from observed culverts. Double fenced areas resulted in a 94% reduction in amphibian road occurrence. Five species of amphibians were observed over the three survey years (4051 road incidences over 657 survey hours): Pacific chorus frog (Pseudacris regilla), Western toad (Anaxyrus boreas), long-toed salamander (Ambystoma macrodactylum) plus blotched tiger salamander and Great Basin spadefoot. This study aims to provide a better understanding of amphibian hotspots on roadways and ecopassage use within the south Okanagan. It may act as a catalyst to further wildlife-vehicle interaction studies with improved mitigation solutions for amphibian roadway fatalities.