65 resultados para Upper Strata

em Brock University, Canada


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During the Upper Cambrian there were three mass extinctions, each of which eliminated at least half of the trilobite families living in North American shelf seas. The Nolichucky Formation preserves the record of one of these extinction events at the base of the Steptoean Stage. Sixty-six trilobite collections were made from five sections In Tennessee and Virginia. The lower Steptoean faunas are assigned to one low diversity, Aphelaspis-dominated biofacies, which can be recognized in several other parts of North America. In Tennessee, the underlying upper Marjuman strata contain two higher diversity biofacies, the Coosella-Glaphyraspis Biofacies and the Tricrepicephalus-Norwoodiid Biofacies. At least four different biofacies are present in other parts of North America: the Crepicephalus -Lonchocephalus Biofacies, the Kingstonia Biofacies, the Cedaria Biofacies, and the Uncaspis Biofacies. A new, species-based zonation for the Nolichucky Formation imcludes five zones, three of which are new. These zones are the Crepicephalus Zone, the Coosella perplexa Zone, the Aphelaspis buttsi Zone, the A. walcotti Zone and the A. tarda Zone. The Nolichucky Formation was deposited within a shallow shelf basin and consists largely of subtidal shales with stormgenerated carbonate interbeds. A relative deepening is recorded In the Nolichucky Formation near the extinction, and is indicated In some sections by the appearance of shale-rich, distal storm deposits above a carbonate-rich, more proximal storm deposit sequence. A comparable deepening-upward sequence occurs near the extinction in the Great Basin of southwestern United States and in central Texas, and this suggests a possible eustatic control. In other parts of North America, the extinction IS recorded In a variety of environmental settings that range from near-shore to slope. In shelf environments, there is a marked decrease in diversity, and a sharp reduction in biofacies differentiation. Although extinctions do take place in slope environments, there IS no net reduction in diversity because of the immigration of several new taxa.

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Presently non-commercial occurrences of Mississippi Valley-type ore assemblages in the Middle Silurian strata of the Niagara Peninsula have been studied. Based on this detailed study, a new poly-stage genetic model is proposed which relates ore mineralization in carbonate environments to the evolution of the sedimentary basin. Sulphide ore mineralization occurred during two episodes: 1. During the late diagenesis stage, which is characterized by compaction-maturation of the sediments, the initial mineralization took place by upward and outward movement of connate waters. Metals were probably supplied from all the sediments regardless of their specific lithologies. However, clay minerals were possibly the main contributors. The possible source of sulphur was from petroleum-type hydrocarbons presently mixed with the sediments at the site of ore deposition. Evidence for this is the fact that the greatest abundance of ore minerals is in petroliferous carbonates. The hydrocarbons probably represent liquids remaining after upward migration to the overlying Guelph-Salina reservoirs. The majority of sphalerite and galena formed during this period, as well as accessory pyrite, marcasite, chalcopyrite, chalcocite, arsenopyrite, and pyrrhotite; and secondary dolomite, calcite, celestite, and gypsum. 2. During the presently ongoing surface erosion and weathering phase, which is marked by the downward movement of groundwater, preexisting sulphides were probably remobilized, and trace amounts of lead and zinc were leached from the host material, by groundwaters. Metal sulphides precipitated at, or below, the water table, or where atmospheric oxygen could raise the Eh of groundwaters to the point where soluble metal complexes are unstable and native sulphur co-precipitates with sphalerite and galena. This process, which can be observed today, also results in the transport and deposition of the host rock material. Breakdown of pre-existing sulphide and sulphate, as well as hydrocarbon present in the host rock, provided sulphur necessary for sulphide precipitation. The galena and sphalerite are accompanied by dolomite, calcite, gypsum, anglesite, native sulphur and possibly zincite.

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A comprehensive elemental, isotopic and microstructural analyses was undertaken of brachiopod calcites from the Hamilton Group (Middle Devonian), Clinton Group (Middle Silurian) and Middle to Upper Ordovician strata of Ontario and New York State. The majority of specimens were microstructurally and chemically preserved in a pristine state, although a number of specimens show some degree of post-depositional alteration. Brachiopod calcites from the Hamilton and Clinton Groups were altered by marine derived waters whereas Trenton Group (Middle Ordovician) brachiopods altered in meteorically derived fluids. Analysis of the elemental and isotopic compositions of pristine Hamilton Group brachiopods indicates there are several chemical relationships inherent to brachiopod calcite. Taxonomic differentiation of Mg, Sr and Na contents was evident in three co-occuring species from the Hamilton Group. Mean Mg contents of pristine brachiopods were respectively Athyris spiriferoides (1309ppm), Mucrospirifer mucronatus (1035ppm) and Mediospirifer audacula (789ppm). Similarly, taxonomic differentiation of shell calcite compositions was observed in co-occuring brachiopods from the Clinton Group (Middle Silurian) and the Trenton Group (Middle Ordovician). The taxonomic control of elemental regulation into shell calcite is probably related to the slightly different physiological systems and secretory mechanisms. A relationship was observed in Hamilton Group species between the depth of respective brachiopod communities and their Mg, Sr and Na contents. These elements were depleted in the shell calcites of deeper brachiopods compared to their counterparts in shallower reaches. Apparently shell calcite elemental composition is related to environmental conditions of the depositional setting, which may have controlled the secretory regime, mineral morphology of shell calcite and precipitation rates of each species. Despite the change in Mg, Sr and Na contents between beds and formations in response to environmental conditions, the taxonomic differentiation of shell calcite composition is maintained. Thus, it may be possible to predict relative depth changes in paleoenvironmental reconstructions using brachiopod calcite. This relationship of brachiopod chemistry to depth was also tested within a transgressiveregressive (T-R) cycle in the Rochester Shale Formation (Middle Silurian). Decreasing Mg, Sr and Na contents were observed in the transition from the shallow carbonates of the Irondequoit Formation to the deeper shales of the lowest 2 m of Rochester Shale. However, no isotopic and elemental trends were observed within the entire T-R cycle which suggests that either the water conditions did not change significantly or that the cycle is illusory. A similar relationship was observed between the Fe and Mn chemistries of shell calcite and redox/paleo-oxygen conditions. Hamilton Group brachiopods analysed from deeper areas of the shelf are enriched in Mn and Fe relative to those from shallow zones. The presence of black shales and dysaerobic faunas, during deposition of the Hamilton Group, suggests that the waters of the northern Appalachian Basin were stratified. The deeper brachiopods were marginally positioned above an oxycline and their shell calcites reflect periodic incursions of oxygen depleted water. Furthermore, analysis of Dalmanella from the black shales of the Collingwood Shale (Upper Ordovician) in comparison to those from the carbonates of the Verulam Formation (Middle Ordovician) confirm the relationship of Fe and Mn contents to periodic but not permanent incursions of low oxygen waters. The isotopic compositions of brachiopod calcite found in Hamilton Group (813C; +2.5% 0 to +5.5% 0; 8180 -2.50/00 to -4.00/00) and Clinton Group (813C; +4.00/00 to +6.0; 8180; -1.8% 0 to -3.60/ 00) are heavier than previously reported. Uncorrected paleotemperatures (assuming normal salinity, 0% 0 SMOW and no fractionation effects) derived from these isotopic values suggest that the Clinton sea temperature (Middle Silurian) ranged from 18°C to 28°C and Hamilton seas (Middle Devonian) ranged between 24°C and 29°C. In addition, the isotopic variation of brachiopod shell calcite is significant and is related to environmental conditions. Within a single time-correlative shell bed (the Demissa Bed; Hamilton Group) a positive isotopic shift of 2-2.5% 0 in 013C compositions and a positive shift of 1.0-1.50/00 in 0180 composition of shell calcite is observed, corresponding with a deepening of brachiopod habitats toward the axis of the Appalachian Basin. Moroever, a faunal succession from deeper Ambocoelia dominated brachiopod association to a shallow Tropidoleptus dominated assocation is reflected by isotopic shifts of 1.0-1.50/00. Although, other studies have emphasized the significance of ±20/oo shifts in brachiopod isotopic compositions, the recognition of isotopic variability in brachiopod calcite within single beds and within depositional settings such as the Appalachian Basin has important implications for the interpretation of secular isotopic trends. A significant proportion of the variation observed isotopic distribution during the Paleozoic is related to environmental conditions within the depositional setting.

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Owing to the fact that low-Mg calcite fossil shells are so important in paleoceanographic research, 249 brachiopod, cement and matrix specimens from two neighboring localities (Jemez Springs and Battleship Rock), of the Upper Pennsylvanian Madera Formation were analyzed. Of which, about 86% of the Madera brachiopods are preserved in their pristine mineralogy, microstructure and geochemistry. Cement and matrix samples, in contrast, have been subjected to complete but variable post-deposition~1 alteration. It is confirmed that the stable isotope data of brachiopods are much better than that of matrix material in defining depositional parameters. Because there is no uniform or constant relationship between the two data bases (e.g., from 0.1 to 3.0%0 for 0180 and from 0.2 to 6.7%0 for 013C in this study), it is not possible to make corrections for the matrix data. Regarding the two stratigraphic sections, elemental and petrographic analyses suggest that Jemez Springs is closer to Penasco Uplift than Battleship Rock. Seawater at Jemez Springs is more aerobic, and the water chemistry is more influenced by continental sources than that at Battleship Rock. In addition, there is a relatively stronger dolomitization in the mid-section of the Battleship Rock. Results further suggest that no significant biogenic fractionation or vital effects occurred during their shell secretion, suggesting that the Madera brachiopods incorporated oxygen and carbon isotopes in equilibrium with the ambient seawater. This conclusion is not only drawn from the temporal and spatial analyses, but also supported by brachiopod inter-generic comparison (Composita and Neospirifer) and statistical analysis ( t-test).

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The Upper Cambrian Pika Formation in the southern Canadian Rocky Mountains forms a complete lithologic Grand Cycle. The overall pattern of deposition is one of shallowing upwards from a subtidal, muddy, storm-influenced basin to a shallow carbonate bank. The Pika passes gradationally into the overlying inter- to supratidal siliciclastics of the Arctomys Formation. This transition probably reflects a fall in relative sea level. 2 Twenty seven collections from three sections yielded trilobites. The faunas are assigned to two low-diversity biofacies: the Marjumia - Spencella Biofacies and the GZyphaspis - menomoniid Biofacies. In contrast to biofacies of deeper, open-shelf environments, such as the Wheeler and Marjum formations of Utah, the Pika biofacies lack agnostid trilobites. Consequently, agnostid-based zonations defined elsewhere in North America cannot be applied to the Pika and a new sequence of three zones and one informal fauna is proposed for use in inner shelf facies. Eleven species belonging to six genera are described and illustrated. The species Marjumia bagginsi is new. Other genera present are: Bolaspidella, Knechtelia, GZyphaspis and Spencella, in addition to a number of indeterminate forms

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Inscribed on verso of front cover: H.R. Morgan Esq. with compts of E.A. Cruikshank.

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Functional Electrically Stimulated (FES) ami cycle ergometry is a relatively new technique for exercise in individuals with impairments of the upper limbs. The purpose of this study was to determine the effects of 12 weeks of FES arm cycle ergometry on upper limb function and cardiovascular fitness in individuals with tetraplegia. F!ve subjects (4M/1F; mean age 43.8 ± 15.4 years) with a spinal cord injury of the cervical spine (C3- C7; ASIA B-D) participated in 12 weeks of3 times per week FES arm cycle ergometry training. Exercise performance measures (time to fatigue, distance to fatigue, work rate) were taken at baseline, 6 weeks, and following 12 weeks of training. Cardiovascular measures (MAP, resting HR, average and peak HR during exercise, cardiovascular efficiency) and self reported upper limb function (as determined by the CUE, sf-QIF, SCI-SET questionnaires) were taken at baseline and following 12 weeks of training. Increases were found in time to fatigue (84.4%), distance to fatigue (111.7%), and work rate (51.3%). These changes were non-significant. There was a significant decrease in MAP (91.1 ± 13.9 vs. 87.7 ± 14.7 mmHg) following 12 weeks ofFES arm cycle ergometry. There was no significant change in resting HR or average and peak HR during exercise. Cardiovascular efficiency showed an increase following the 12 weeks ofFES training (142.9%), which was non-significant. There were no significant changes in the measures of upper limb function and spasticity. Overall, FES arm cycle ergometry is an effective method of cardiovascular exercise for individuals with tetraplegia, as evidenced by a significant decrease in MAP, however it is unclear whether 12 weeks of thrice weekly FES arm cycle ergometry may effectively improve upper limb function in all individuals with a cervical SCI.

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In March 1931, Captain Bruce Angus was sent to Sarnia by Gordon C. Leitch, general manager of Toronto Elevators. He was sent to inspect the Sarnian to ensure it was still seaworthy. Leitch was a savvy business man, who had been active in the business community for a number of years. Leitch began his career with a partner in the lumber business. When that went under he moved into graineries and worked for the Winnipeg Wheat Pool for 12 years. After Winnipeg he moved to Toronto, which was closer to his home town of Ridgetown, Ontario. In Toronto Leitch became manager of the Toronto branch of the Canadian Wheat Pool. While managing the wheat pools in Toronto Leitch became aware of huge costs associated with shipping the grains from the praries into the Toronto area. He felt that there was no need for such costs and decided to do something to make them better and cheaper for the business. Originally the grain was loaded onto Lakers that would bring the grain from the praries to Lake Huron and Georgian Bay. It was stored there until needed by the Toronto graineries and then hauled across land by either truck or train. The land journey was the most expensive and the one which Leitch wanted to eliminate. This was a fine plan except for 2 obstacles that were quickly overcome. First of all the Welland canals were not large enough to accommodate the large carriers that were bringing in the grain. This was changing as the expansion and widening of the canals was already underway. The second issue was the lack of storage in Toronto for the grain. The grain elevators had been destroyed by fire in the late 1880s and never replaced. Leitch propsed his company built its own storage elevators along the water front to allow not only for easier access to the grain, and more timely production of products. The elevators would aslo create a reduction in shipping costs and an overall more competitoive price for the customers of the grainery. The company refused, so Leitch went elsewhere to friends and contacts within the grain industry. The elevators were built and Leitch quit his job with the Canadian Wheat Pool and became the general manager of the elevators. Although the elevators were built and ready for storage the next issue was filling them. None of the carriers wanted to do business with Leitch because the competition in Georgian Bay threatened to cancel their contracts if they did. Leitch saw no way around this, but to provide his own transportation. This is when he sent Captain Bruce Angus to scout out potential ships. The ship was purchased for $37,000 and after another $30,000 was spent to fix it up, it was ready for business. The need for transportation and the finding of a seaworthy ship, lead to the beginnings of the Northland Steamship Company. The Sarnian proved to not be enough for the business underway. Leitch decided another ship was necessary. He joined forces with James Norris the owner of the Norris Grain Company. He proposed they join forces to create a more economical means of transportating their products.

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The Statutes of his Majesty's Province of Upper Canada in North America outlining the recruitment, administration and discipline of the militia.

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Full Title: A geographical view of the province of Upper Canada : and promiscuous remarks on the government, in two parts, with an appendix, containing a complete description of the Niagara Falls, and remarks relative to the situation of the inhabitants respecting the war, and a concise history of its progress, to the present date. William and David Robinson, Printers