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The Alberta Basin has been the subject of various diagenetic studies but the precise understanding of the processes behind deep burial cementation remains unclear. This study investigates late-diagenetic calcites from the Devonian Southesk-Cairn Carbonate Complex with the purpose of constraining temperature, relative timing and chemistry of the paleo-fluids involved during calcite precipitation. Two types of late-diagenetic calcites were petrographically andgeochemicallycharacterized.Whereascalcite-Iresultedfrom thermochemical sulfate reduction, calcite-II precipitated with no or little oxidized organic carbon present. As shown by the Sr isotopic signatures, some reservoirs were exposed to radiogenic Sr-bearing fluids. A slight trend of increasing fluid inclusion homogenization temperatures with depth is only seen in calcite-I, and bitumen reflectance also increases with depth following a normal burial gradient. These results, however, are not conclusive to interpret the influence of tectonically-driven fluids during deep burial.

Hydrothermal veins in the Paleozoic of the Barrrandian testify for fluid migration during diagenesis and/or epigenesis. A more detailed mineralogical and geochemical research of these veins has started since the end of the 20th century. The subject of a research included in this thesis is determination of conditions of formation of syntectonic calcite and quartz-calcite veins in the lokality called Žák's quarry in Velká Chuchle. This thesis is based on field determination of succession of hydrothermal veins and laboratory study of fluid inclusions in minerals as a basic tool for determination of temperatures during formation of veins. In total, there were distinguished four types/generations of calcite and quartz-calcite veins in Žák's quarry (from oldest to youngest): 1) veins of ,,beef calcite", 2) veins with flat crystals of smoky quartz located in joints perpendicular to bedding, 3) shear veins with calcite located in the big fold, 4) a big calcite vein with tectonic striae spatially bound to significant local fault. Veins have thickness aproximatelly from 1 mm to about 15 cm. By the way, veins of ,,beef calcite" are characteristic by orientation of prolonged grains of calcite in the direction orthogonal towards to the plane of vein. The microscopic study of fluid inclusions revealed presence of...

The results of a combined mineral equilibria and fluid inclusion study show that the Manhattan Prong, southeastern New York, has experienced multiple metamorphic events. Two episodes of intrusion, separated by approximately 100 million years, have superimposed contact aureoles on the Taconic regional metamorphic gradient in the northeastern Manhattan Prong and have modified the regional assemblage to different degrees. The assemblage Sil-Bt-Grt-Qtz-Pl+Ksp+Ms in regionally metamorphosed Manhattan Schist records P-T conditions of 4-5 kbar and 650-700 oC. Garnet porphyroblasts, homogenous with respect to major elements but zoned with respect to P and Y, contain ubiquitous, primary, CO2-rich fluid inclusions which have a Th = 10-24 oC. Manhattan Schist collected adjacent to the Croton Falls and Peach Lake mafic complexes, intrusions thought to be related to the Late Ordovician Cortlandt Complex, record P-T estimates of 4 kbar and 700 oC and 4.2 kbar and 550-600 oC respectively. The lack of fluid inclusions in garnet porphyroblasts indicates that the regional metamorphic assemblage has been completely modified by the contact effects of the mafic intrusions. However, the presence of Ky+Sta along with the slight compositional zoning of garnets in Peach Lake samples suggests that the contact assemblage may have been modified by a later metamorphism. Manhattan Schist collected adjacent to ~350 Ma granites (Brock, 1993) has been partially modified by contact metamorphism and shearing but vestiges of the regional metamorphic assemblage remain. Garnet porphyroblasts contain abundant CO2-rich fluid inclusions and P-T estimates using Bt and Pl inclusions and garnet core compositions are similar to estimates of regional metamorphic conditions. Evidence of modification includes garnet overgrowths that are elevated in Ca and depleted in Mn, Y and Sc, and CO2-rich fluid inclusions that have reequilibrated to higher density (Th = 2-18 oC). Rim compositions of porphyroblasts yield P-T estimates of 5-6 kbar and 550-600 oC. The elevated Ca content of the overgrowths along with the presence of Ky in the matrix suggests that the reaction An = Ky + Grs + Qtz may have been active during the overprinting metamorphism. The increase in pressure recorded in the granite aureoles in the Manhattan Prong is inconsistent with the results of P-T studies of the Rowe-Hawley belt, approximately 20 km to the east across Cameron's Line. This suggests that these two terranes may have been separated in the Devonian. / Master of Science

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第18802号 / 理博第4060号 / 新制||理||1584(附属図書館) / 31753 / 京都大学大学院理学研究科地球惑星科学専攻 / (主査)教授 竹村 惠二, 教授 平原 和朗, 教授 大沢 信二 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

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<P> The Faymar Gold Property, near Timmins Ontario, is cross-cut by two quartz-carbonate veins. Isotopic measurements of carbon species in fluid inclusions in these quartz-carbonate veins, reveal the presence of CO2 and other light carbon species (eg. CH4). The inclusion contents were liberated using thermal decrepitation. The results obtained are found to vary quite significantly with various periods and temperatures of heating. The most useful results were obtained from samples heated for 5 minutes at 550 °C. The short heating period reduces fractionation and reaction effects. Mass spectrometer measurements of the carbon isotopes reveal that the CO2 and total carbon in the inclusions are characterized by a δ13c of -3.O and -4.7 respectively. A magmatic source for the fluids most easily explains these values. Petrographic observations indicate that secondary inclusions dominate. Thus, the isotopic measurements are of fluids which post-date the deposition of the quartz-carbonate or at least represent a late stage of this process. Since the mineralization in the veins also appears to be secondary to the quartz-carbonate (ie. in fractures), it is possible that the carbon species in the inclusions are distinct of the mineralizing fluids. </p> / Thesis / Bachelor of Science (BSc)

<p> The Meguma Group is situated in the southeastern and southwestern regions of Nova Scotia. The Meguma Group is divided into two formations: the Goldenville and the Halifax. Both formations are comprised of A and E divisions of the Bouma sequence. Thus, the Meguma Group is a turbidite deposit. Auriferous quartz veins strike parallel to bedding and occur between the lower Bouma cycle's E division and the overlying Bouma cycle's A division. The development of bedding-parallel veins was due to hydraulic fracturing of the Bouma units.</p> <p> The bedding-parallel quartz veins were emplaced at low temperatures, from 260°C to 300°C. The fluid which precipitated the gold-arsenopyrite-quartz veins consisted of a divalent cation salt species (MgCl2) and hydrosulphide ligands which were the main complexing agent of gold.</p> <p> Gold was precipitated due to the reduction of sulphide ligands as they came into contact with the organic-rich slates of the E division of the Bouma sequence. Sulphide reduction was not complete, thus a large concentration of gold remained in solution later to be precipitated with arsenic in arsenopyrite.</p> / Thesis / Bachelor of Science (BSc)