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Alpine karst throughout the world has been affected by past glaciation, and yet little is known of the interactions between glacier ice and karst. This dissertation attempts to gain some understanding of the problem through the study of the Castleguard Area, Alberta, where a karst aquifer is presently overlain by temperate glacier ice.
Quantitative fluorometric tracing and hydrometric measurements generated a broad data base on aquifer behaviour. Tracer breakthrough curves were interpreted using a new systematic approach which considers an explicit set of processes likely to affect the particular tracer under the given experimental conditions. Non-linearity in aquifer behaviour and rapid groundwater velocities demonstrated the aquifer to be an extreme conduit type Conduit springs are elements in a vertical hierarchy in which the topmost springs are "overflows" and exhibit greater flow variability than their associated "underflows". A numerical model was developed to simulate a conduit aquifer. It demonstrated that pulse train and recession analysis widely accepted methods of karst aquifer investigation, could be rather misleading when applied to conduit aquifers.
Interactions between ice and groundwater were observed at two scales: regulation water appeared to feed a diffuse percolation system and supraglacial melt passed into subglacial conduits which entered open vadose shafts. Karst is unlikely to be entirely subglacial in origin because of the limited aggressiveness of subglacial waters.
The Castlegaurd karst appeared to have originated preglacially in response to the breaching of impermeable caprock. Glaciation re-ordered the landscape and produced abundant clastic debris which subsequently blocked or obstructed karst conduits. Much of the resulting karst is paragenetic and comparatively immature due to glacial disruption and slow growth rates. Geomorphic and hydrologic interactions between ice and karst depend intimately upon the relationship between the geographic zones of the glacier and the aquifer.
The relative significance of straw speleothem growth from evaporation and from CO2 degassing was determined in Lilli-Pilli and Moons Caves (Buchan, Victoria) from a seven-month study of cave climate and water chemistry. The relative importance of these two mechanisms was inferred from the calculation of the straw growth rates according to a degassing model and an evaporation model. The modelled straw growth rates from the carbon dioxide degassing model were on hundred to one thousand times those attributable to evaporation. A third model was used to calculate straw growth rates from the overall supersaturation of the water. Growth rates were found to be within the range of 0.01 to 0.07mm per annum.
The aim of this project was to collect samples of stalagmites from Northern and Central America in order to produce records of the palaeosecular variation of the earth's magnetic field. Two stalagmites were sampled from Western Canada and ten from Mexico and Guatemala which could be compared with contemporaneous stalagmite records from these areas (Latham, 1981; Latham et al, 1982; 1986; 1987; 1989).
The stalagmites were generally weakly magnetised but remanence directions were stable upon stepwise thermal and alternating-field demagnetisation. Consistency in directions recorded between central and corresponding lateral sub-samples within two stalagmites (MSC2 from Canada and CP1 from Guatemala) inferred that any depositional errors caused by surface effects were less than the measurement errors. Grain size analysis showed the presence of a fine-grained magnetic fraction (0.01 - 0.1?:m) sourced from the cave drip-waters (either by direct deposition or by chemical precipitation) and a coarser magnetic fraction (0.01 - >10?:m) sourced from the flood-borne detritus. The latter source was dominant in stalagmites which were regularly inundated with water. The type of magnetic mineral present was determined by the geology of the catchment area; magnetite dominated in the Vancouver Island stalagmites, titanomagnetite in the Mexican stalagmites and haematite in the Guatemalan stalagmite.
Uranium-series dating of samples was hindered by the young ages of many of the samples, by low uranium concentrations and by the presence of allogenic thorium. If significant amounts of allogenic thorium were present, a sample age could be calculated based on an estimate of the initial thorium ratio ([230Th/232Th]0). Analysis of samples from Sumidero Recuerdo in Mexico, however, suggested that this ratio is not constant with time and may vary by a factor of two over approximately 1700 years. Due to these imprecisions many dates were out of stratigraphic sequence and age estimates were made assuming constant growth rates, except where growth had ceased for a finite length of time.
Records of sequential change of palaeomagnetic direction were obtained from the Mexican stalagmite SSJ3 and the Canadian stalagmite MSC2. The reliability of the latter record was confirmed by comparison with another Canadian stalagmite record (Latham et al, 1987) and contemporaneous lacustrine records. Other records were disappointing due to poor temporal resolution; each sub-sample represented a period of approximately 1000 years in Mexican stalagmites SSJ2 and SSJ4. Such slow growth rates are insufficient for the resolution of secular variation features with periods of less than 2000 years and are only suitable to gain information about the nature of long-term secular variations, for example the far-sided virtual geomagnetic poles and low inclinations predominant throughout the Holocene in Southern Mexico.
The existence of matching contemporaneous stalagmite records of secular variation together with the demonstrated lack of depositional inclination errors is encouraging, despite the sometimes "hit or miss" aspects of sample selection. Nevertheless it has been proved that speleothem records have the potential to complement the existing archaeomagnetic, lava and lacustrine data.
This study has produced records of the palaeosecular variation (PSV) of the earth's magnetic field from Speleothems from China and Spain. The ultimate aim of this project was to produce contemporaneous PSV records which would show that Speleothems accurately record ambient geomagnetic field behaviour. From Sichuan Province, China, five Speleothems were collected of which four were studied for their records of PSV. Eight Spanish Speleothems from the Cantabrian coast were collected but their weak magnetisation allowed only one record of PSV to be produced.
All speleothem sub-samples were weakly magnetised and had, on average, initial intensities of <100 x 10-8 Am2kg-1. Despite this, the majority of sub-samples were stable during stepwise alternating-field and thermal demagnetisation and each displayed a single component of magnetisation after removal of any secondary overprints. Rock magnetic experiments were hampered by low mineral concentrations but suggested that the remanences of each speleothem were carried by a mixture of multi and single-domain (titano-) magnetite and also by haematite present in significant quantities. The primary method of remanence acquisition appeared to be a depositional remanence sourced from flooding. This was corroborated by a linear relationship between sub-sample intensities and weight % acid insoluble detritus.
A selection of sub-samples from each speleothem were dated using uranium-thorium disequilibrium and alpha spectrometry. For the majority of sub-samples the low concentrations of uranium, high levels of detrital contamination and initially low chemical yields raised the associated dating inaccuracies above the quoted level for alpha spectrometry of 5-10%. Two Spanish Speleothems had high uranium concentrations and little, or no, detrital contamination. Percent age errors of these Speleothems ranged from 1 to 6%. Comprehensive experiments on the efficiencies of three electrodeposition methods were also undertaken. The most efficient method was found to be a modified version of the Hallstadius method (Hallstadius, 1984), which consistently achieved chemical yields between 40 and 90% for uranium and thorium.
In order to correct more analytically for the presence of detrital contamination, the leachate/leachate method of Schwarcz and Latham (1989) was tested. The maximum likelihood estimation data treatment technique (Ludwig and Titterington, 1994) was used to calculate dates from these analyses. Tests on Mexican speleothem SSJ2 gave excellent results allowing a revised dating scheme to be adopted. Tests on some sub-samples from Chinese Speleothems were generally unsuccessful due to analytical errors.
The isotope 210Pb was used to date the top surface of one speleothem. A constant growth rate was inferred which was significantly less than that calculated from the 230Th - 234U dating method. This was thought to be due to the former techniques inability to resolve growth rates of periods of less than 200 years.
Despite the dating errors associated with each speleothem the records of PSV compare well with each other and with contemporaneous records from China, Japan and also the UK (for the Spanish record). In addition. agreement with PSV data modelled from observatory records suggested that westward drift of the non-dipole geomagnetic field was predominant during the past 10ka.
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