3 resultados para Reconnaissance de formes

em Brock University, Canada


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The Island Lake greenstone belt is one of the major Archean supracrustal exposures in the northwestern part of the Superior Province of the Canadian Shield. This belt is subdivided into two units: 1) a lower sequence characterised by pillowed to massive, locally pyroclastic, basalt to andesite with a thin central zone of felsic derivatives, all of which are interbedded with and overlain by thick sequences of turbidite facies rock; 2) the upper unit which consists of thick stratified conglomerate overlain by thickly bedded arkose and feldspathic greywacke. Reconnaissance sampling traverses were completed across both the strike of the belt and along its margins with adjacent granitoids. Most of the belt is within the greenschist metamorphic f acies with amphibolite facies occurring in certain areas near t he margins. A post-tectonic, low pressure thermal event may be responsible for the development of a unit of cordierite schi s t which stretches southeastwards from the east end of Cochrane Bay. Volcanism is cyclical in nature changing from tholeiitic to calc-alkaline. There is a general progression in the character of the lavas from mafic t o felsic with stratigraphic height. Chemica l d a ta sugges t that h i gh level fractionation of a mantle- derived ' dry' magma i s t he s ource of the thole i iti c lavas. Contamination of this magma with 'we t' sia l and subsequent fractionation may be r esponsi b l e for the calcalkaline phases .Observations of stratigraphic relationships (in particular the contact between the supracrustals and the granitoids) coupled with the metamorphic and chemical studies, allow the construction of a preliminary model for the evolution of the Island Lake greenstone belt. The following sequential development is suggested: 1) a platform stage characterised by the subaqueous effusion of mafic to intermediate lavas of alternating tholeiitic and calc-alkaline affinities; 2) an edifice stage marked by the eruption of felsic calc-alkaline rocks; 3) an erosional stage characterised by the deposit~on of thick sequences of turbidite facies rocks; 4) the impingement of granitic masses into the margins of the greenstone belt, which was probably related to a downward warping of the supracrustal pilei 5) the erosion of sialic massifs surrounding and within the greenstone belt and of early supracrustal piles, to give the clastic upper unit.

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A regional geochemical reconnaissance by bottom stream sediment sampling, has delineated an area of high metal content in the north central sector of the North Creek Watershed. Development of a geochemical model, relating to the relative chemical concentrations derived from the chemical analyses of bottom sediments, suspended sediments, stream waters and well waters collected from the north central sector, was designed to discover the source of the anomaly. Samples of each type of material were analysed by the A.R.L. Direct Reading Multi-element Emission Spectrograph Q.A. 137 for elements: Na, K, Ca, Sr, Si, As, Pb, Zn, Cd, Ni, Ti, Ag, Mo, Be, Fe, AI, Mn, Cu, Cr, P and Y. Anomalous results led to the discovery of a spring, the waters of which carried high concentrations of Zn, Cd, Pb, As, Ni, Ti, Ag, Sr and Si. In addition, the spring waters had high concentrations of Na, Ca, Mg, 504 , alkalinity, N03' and low concentrations of K, Cl and NH3. Increased specific conductivity (up to 2500 ~mho/cm.) was noted in the spring waters as well as increased calculated total dissolved solids (up to 2047 mg/l) and increased ionic strength (up to 0.06). On the other hand, decreases were noted in water temperature (8°C), pH (pH 7.2) and Eh (+.154 volts). Piezometer nests were installed in the anomalous north central sector of the watershed. In accordance with the slope of the piezometric surface from wells cased down to the till/bedrock interface, groundwater flow is directed from the recharge area (northwest of the anomaly) towards the artesian spring via the highly fractured dolostone aquifer of the Upper Eramosa Member. The bedrock aquifer is confined by the overlying Halton till and the underlying Lower Eramosa Member (Vinemount Shale). The oxidation of sphalerite and galena and the dissolution of gypsum, celestite, calcite, and dolomite within the Eramosa Member, contributed its highly, dissolved constituents to the circulating groundwaters, the age of which is greater than 20 years as determined by tritium dating. Groundwater is assumed to flow along the Vinemount Shale and discharge as an artesian spring where the shale unit becomes discontinuous. The anomaly is located on a topographic low where bedrock is close to the surface. Thermodynamic evaluation of the major ion speciation from the anomalous spring and surface waters, showed gypsum to be supersaturated in these spring waters. Downstream from the spring, the loss of carbon dioxide from the spring waters resulted in the supersaturation with respect to calcite, aragonite, magnesite and dolomite. This corresponded with increases in Eh (+.304 volts) and pH (pH 8.5) in the anomalous surface waters. In conclusion, the interaction of groundwaters within the highly, mineralized carbonate source (Eramosa Member) resulted in the characteristic Ca*Mg*HC03*S04 spring water at the anomalous site, which appeared to be the principle effect upon controlling the anomalous surface water chemistry.

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Percy Carruthers Band was born on November 27, 1892 in Toronto, Ontario to Charles Walter Band, a grain merchant and Jessie Camp Shaw Band. He graduated from Upper Canada College and became a broker. He worked at the Dominion Bank and then at Maple Leaf Milling Company. He was stationed at Port Colborne for a while. Before leaving for the front, he was with Bankers Bond Company of Toronto and is also listed as working with the firm of Bailey, Wood and Cross. Lieutenant Band received a Certificate of Military Qualifications on Dec. 24th, 1914. He received his Certificate of Military Instruction on Nov. 30, 1915. He received these certificates while with the 48th Regiment (Highlanders). He enlisted in 1914 and went overseas in August of 1915 as an officer in the 35th Battalion. By August 26, 1915, he is listed as being with the 23rd Reserve Battalion. A year later, in August of 1916 Lieutenant Band arrived in France and was posted to the 2nd Battalion – “The Second Iron”. In 1916, Band was the victim of shell shock received during a charge. He was wounded in April of 1917 at Vimy Ridge yet he remained on duty. At this time he received a gunshot wound to his right jaw. He earned a promotion to Captain on September 16th, 1917. He was wounded again in November of 1917 at Passchendaele where he suffered a gunshot wound to the ear. For his courage and determination Percy Band received the Military Cross on February 18, 1918. He led his company under difficult circumstances even though he was wounded. He was awarded a bar to the Military Cross for gallantry during a successful attack on two villages on December 2nd, 1918. During this attack he led his company against enemy machine guns. It is said that he displayed exceptional leadership qualities and skill during this time. On the 30th of August in 1918, he made a daring reconnaissance to the front under heavy fire in an attack on Upton Wood. He was also commended on his gallantry during attacks on Cagnicourt and the Canal du Nord in September of 1918. He was awarded the second bar to the Military Cross on February 1, 1919. The award of the Croix de Guerre was conferred on Captain Percy Carruthers Band by the President of the French Republic on December 15th, 1918 for distinguished service rendered during the course of the campaign. His general demobilization took place on April 25, 1919. Percy Band married Margaret Julia Woodruff on November 25, 1919, and they had three children: Charles Woodruff Band (1921), Margaret Elizabeth Band (1924) and Robert DeVeaux Woodruff Band (1927). After the war, Mr. Band was a manager at Geo. Weston Bread and Cakes Limited, St. Catharines. Percy Band was also an avid collector. His collections included antique toys and art. He died suddenly on May 19, 1961. The Toronto Telegram published this about him: “Captain Percy Carruthers Band, M.C. with two Bars, Croix de Guerre with Palm – was an officer whose buoyant spirit and gallantry mirrored the vibrant soul of the Battalion. Blythe of heart, yet endowed with a fine sense of responsibility, he gave inspired leadership of No. 3 Company.”