No description available.

This study uses field, petrographic, fluid inclusion microthermometric, stable isotope and palaeomagnetic techniques to demonstrate that there have been multiple episodes of post-metamorphic, surface-derived fluids infiltrating into the crystalline basement rocks of Southwest Scotland and Northern Ireland. The timing of different episodes of regional fluid infiltration can be related to the tectonic evolution of the area. Late Caledonian faulting within the crystalline basement rocks of the Grampian Highlands and the Southern Uplands region acted as loci for the infiltration of surface-derived fluids. These earliest fluids deposited gold in the Southern Uplands and base metals and gold in the Grampian Highlands. Subsequent infiltration of surface-derived fluids within reactivated Caledonian faults in the crystalline basement rocks of Southwest Scotland and Northern Ireland during Carboniferous N-S regional extension resulted in the formation of basement-hosted, stratabound, base metal mineralization. The Highland Boundary Fault acted as a regional pathway for the penetration of post-metamorphic, surface-derived fluids in Middle Devonian, Lower Carboniferous and late Carboniferous times. Reactivated Caledonian faults in the Grampian Highlands of Scotland also acted as loci for the penetration of oxidising, meteoric fluids into shallow crustal levels during late Permian to early Triassic times. Surface-derived fluids circulating within Caledonian faults that were reactivated during the early plate separation of the North Atlantic in Triassic/Jurassic times resulted in the formation of stratabound barite mineralization in the Midland Valley and uranium mineralization in association with a post-tectonic pluton on the North Solway coast in Southern Scotland.

No description available.

Three colonies of wood-ants Formica lugubris were taken from native Caledonian pinewoods and re-established in the laboratory. Experiments were conducted during which each of these colonies was provided with two discrete patches at which foragers could drink from filter papers saturated with aqueous solutions of sucrose; these patches were replenished continuously with the solutions. Three series of experiments were conducted in which the hypothesis tested was that the ants would distribute themselves between the patches according to the ideal free distribution. During the first series of experiments, the rate of supply of sucrose was manipulated by changing the concentrations of the solutions while maintaining equal rates of supply. Under each concentration ratio an equilibrium distribution was established. When the concentrations were equal, foragers distributed in a ratio of 1:1. When the concentrations were unequal the proportion of foragers at the richer patch was consistently less than the proportion of sucrose available there; ratios of sucrose of 1:2 and 1:4 were associated with equilibrium distributions of foragers in the ratios of approximately 1:1 and 1:2 respectively. In the second series of experiments, it was shown that these ratios were dependent on the overall rate of regeneration of the solutions; increases in the overall rate of regeneration were associated with increased proportional occupation of the richer patch. Throughout this experiment, the concentrations of the solutions were 7% w/v and 28% w/v and the rates of regeneration of the solutions at both patches were equal. Distributions were established at four different rates of regeneration. At the lowest rate of regeneration (0.2ml.h-1) the proportion of foragers at the richer patch was significantly lower than the ideal free prediction of 0.8. At the three higher rates of regeneration (0.4ml.h-1, 0.6ml.h-1 and 0.8ml.h-1) the proportion of foragers at the richer patch was significantly greater than the proportion of sucrose available there.

The Trans-Suture Suite (TSS) of granitic plutons located in Northern Britain span the Iapetus Suture and represent a particularly enigmatic stage of post-Caledonian Devonian magmatism. Despite calc-alkaline affinities, proximity to the Iapetus Suture precludes a direct relationship to active subduction. Furthermore, the absence of inherited zircons distinguishes the TSS from plutons of a similar age throughout the Scottish Highlands, and is not easily reconciled with the abundance of peraluminous and S-type granites. Micro-analytical techniques are employed to analyse accessory zircon and apatite from three TSS plutons (Criffell, Fleet and Shap) in order to investigate connections between magmatic and tectonic processes within a continental suture zone. Accessory minerals contain a robust and accessible record of magma evolution. However, their trace element compositions are shown to document the final stages of pluton emplacement only, and are determined primarily by competitive crystallisation of other accessory phases at shallow crustal levels. By contrast, whole-rock compositions record an earlier stage of magma evolution that occurred in deeper and open-system crustal hot zones. The absence of inherited zircon in the final crystal assemblage reflects resorption during rapid and potentially adiabatic ascent of super-liquidus and water-rich magmas from the crustal hot zone. The concentrations of REE in apatite inclusions decrease with increasing crystallisation of other accessory minerals and in some samples have been distinguished on the basis of their host phase. In metaluminous granodiorites, no preferred crystallisation sequence is observed between host phases. In peraluminous samples, zircon-hosted apatite compositions appear more primitive compared to those hosted by other phases and reflects earlier saturation of zircon in these magmas. The isotopic record of zircon is shown to be biased towards earlier stages of magma evolution in peraluminous magmas and provides a means of assessing zircon isotope compositions in the context of often protracted histories during silicic magma evolution. The Mn content of apatite varies independently to whole-rock composition, correlating positively with decreasing oxygen fugacity and indices of increasing reduction. Apatite is proposed as a robust and effective redox proxy with application to magmatic, detrital and lunar studies of redox conditions. Zircon O-HfU- Th-Pb isotope compositions have identified increasing degrees of compositional heterogeneity in more silicic components of the TSS, including the involvement of more mafic magmas in the generation of the large S-type pluton of Fleet. Compositional trends between zircons from plutons emplaced on both sides of the Iapetus Suture are used to identify a common Avalonian component beneath the Southern Uplands and English Lake District related to Avalonian underthrusting beneath the Laurentian margin during the late Caledonian. New geochronological dating indicates that pluton emplacement occurred during periods of both pre- and post-Acadian transtension. The distinguishing characteristics of these plutons relative to other Caledonian plutons reflect their unique emplacement into the hydrated lithosphere of the Iapetus Suture Zone. Oxygen isotope disequilibrium between the magmatic compositions recorded by zircon and those of the whole-rock and some quartz crystals reflect hydrothermal alteration of the latter two archives. Hydrothermal alteration and exchange caused by 18O-rich magmatic fluids has elevated the 18O compositions of the whole-rock and some quartz crystals, with most disequilibrium observed around the outer margins of the plutons due to further fluid interaction with local 18O-rich sediments. The hydrothermal history of the TSS is markedly different from that of the British Tertiary Igneous Province where hydrothermal alteration resulted from circulation of meteoric water, reflecting significantly different magmatic and emplacement histories.

Thesis (Ph.D.)--Australian National University, 2003.

No description available.

Spatial competition indices for Scots pine and birch growing in heterogeneous Caledonian forest in Glen Affric were developed. Competition indices (CIs) have frequently been used in empirical models of individual tree growth. However, the contribution of CIs to the predictive ability of growth models is often very small. The poor performance of CIs may relate to the choice of spatial descriptors and functional form of the index. To improve CI performance a novel approach utilising neural networks and simulated annealing for the optimisation of CIs was developed.

This study is a detailed investigation concerning the construction of granite plutons by the incremental emplacement of granitic sheets. The modem consensus is that sheeted plutons are often controlled by tectonic structures such shear zones. The Main Donegal Granite (MDG), NW Ireland forms the basis to this study. This pluton is the largest presently exposed member of the Caledonian Donegal Batholith (~405 Ma). Field evidence from this highly deformed pluton, attest to emplacement along the long-axis of a sinistral transcurrent shear zone. The presence of long and persistent xenolith "trains" within the pluton has been taken as evidence of an overall sheeted structure; however detailed maps have not been available to test this hypothesis. Two earlier members of the Donegal Batholith, the Ardara and Thorr plutons, whilst having their main outcrops outside the MDG, also occur as xenoliths within the main body. It can be demonstrated in a number of critical situations that these xenoliths are commonly more deformed than the host MDG facies. Furthermore the presence of original country rock contacts implies these xenoliths were originally in situ. These features imply that the shear zone was active prior to the emplacement of the MDG, with it controlling the emplacement of substantial parts of these earlier plutons. Further evidence from the study of parts of the petrographically similar and younger Trawenagh Bay Granite implies the sinistral shear zone was still operational after the majority of the MDG had crystallised. New, detailed (scale 1:250) and reconnaissance mapping of the MDG, reveals its hitherto unrecognised heterogeneity. At least seven major plutonic zones or packages have been identified. All these units have an NE -SW elongate form parallel to the long axis of the pluton and are often, but not always, separated by extensive "raft-trains" of country rock and older plutons. The major packages in the central regions of the pluton are often complex and are composed of three main granitoid phases, ranging in composition form early granodiorites and tonalites to latest porphyritic and to lesser extent equigranular, monzogranites. The early granodiorite and tonalite sheets are now only preserved as xenolithic rafts within the later monzogranites. The broad range in composition/chemistry together allied with field observations implies a complex intrusion history, with these granitoid packages representing sites of long-standing intrusion within the pluton. In contrast, towards the more marginal areas of the pluton there are large units of monzogranite which are characterised by general homogeneity, but in reality are believed to consist of relatively small compostionally similar sheets. On all scales, either meta-sediments, older plutonic material, or early MDG facies are found to lie along the boundaries of younger intrusive units. This implies the pluton is primarily sheeted in character and that the "raft-trains" are partially disrupted, in situ roof material which has been wedged apart during the intrusion of the sheets. The appearance of sheets within the field is dependent on the rheology of the material into which the granitic material was intruded into, i.e. to what extent has the host was crystallised. The degree of crystallisation in the host is related to how fast later sheets were being intruded, i.e. the rate of emplacement. The field relationships, in the central regions of the pluton, between the granodiorites tonalites and the later monzogranites, are interpreted as representing zones of episodic-to slow emplacement, where earlier phases had become essentially competent by the time later units were intruded (i.e. capable of fracture). These earlier phases may be preserved as angular rafts within later sheets. At moderate emplacement rates earlier sheets may still be crystallising but sufficiently viscous to prevent mixing, except at their immediate boundaries with transitional contacts developing. The more homogeneous zones are believed to be related to rapid emplacement with original contacts between pulses being destroyed at the level of emplacement due to homogenisation of pulses which had similar viscosities and hence allowed mixing. The emplacement of granitic melts within active shear zones can lead to the development of a self- perpetuating situation, where melts in a shear zone will enhance deformation rates and cause greater displacements subsequently allowing more melt to enter the shear zone promoting even greater displacement rates. This process is only halted when melts within the source regions are drained; hence the rate of pluton construction and appearance of sheets within plutons is ultimately related to how fast granitic melts are being generated within the source regions.

Thesis (Ph.D.)--Aberdeen University, 2007. / Title from web page (viewed on Mar. 2, 2009). Includes bibliographical references.