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21.
Ihsan S. Al-Aasm 《Aquatic Geochemistry》2000,6(2):227-248
Mississippian shoal carbonates of Western CanadaSedimentary Basin are important hydrocarbon hosts.Dolomitization plays a major role in the evolution ofreservoir porosity in these carbonates. This processvaries across the basin and reflects, in part, divergentsources and chemistry of pore fluids. Dolomites fromseveral petroleum reservoirs were analyzed formineralogical, geochemical and isotopic variation. Thedata clearly demonstrate the progressive and complexrecrystallization of dolomite during shallow and deepburial in modified marine, meteoric and burial fluids.These data include: change in crystal size,stoichiometry, cathodoluminscence characteristics,stable oxygen and carbon isotopic shifts and changesin radiogenic Sr isotopic composition. However,regional geology, tectonic history and fluid flowevolution play important roles in the diageneticimprints and the degree of recrystallization.Early microcrystalline dolomite formed in normalmarine and evaporative conditions in Mississippiancarbonates from Western Canada Sedimentary Basinhave undergone variable degrees of recrystallization, frompristine dolomite akin to Holocene sabkha dolomitewith preserved mineralogical and chemical attributesto highly recrystallized mesodolomite, however stillnonstoichiometric, but with highly altered chemicalsignatures. Careful attention should be made to localgeology, hydrodynamics and fluid flow when investigatingdolomite recrystallization in sedimentary basins. 相似文献
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23.
Ahmad Hammad Ali Asad Fatima Syeda Hira Zaidi Farrah Khisroon Muhammad Rasheed Syed Basit Ullah Ihsan Ullah Saleem Shakir Muhammad 《Stochastic Environmental Research and Risk Assessment (SERRA)》2020,34(7):1023-1036
Stochastic Environmental Research and Risk Assessment - During the span of August–October, 2017 a major outbreak of Dengue fever happened in Khyber Pakhtunkhwa province of Pakistan. Cases... 相似文献
24.
Hydrothermal alteration zones have been investigated by X-ray diffraction, mineralogical–petrographical techniques, and geochemical analysis. Examination of cores and cuttings from two drill sites, obtained from a depth of about 814–1020 m, show that the hydrothermal minerals occuring in the rock include: K-feldspar, albite, chlorite, alunite, kaolinite, smectite, illite, and opaque minerals.In the studied area, silicified, smectite, illite, alunite, and opal zones have been recognized. These alteration mineral assemblages indicate that there are geothermal fluids, which have temperatures of 150–220°C in the reservoir.The distribution of the hydrothermal minerals shows changes in the chemical composition of the hydrothermal fluid, which are probably due not only to interaction with host rock, but also to dilution of the Na–K–Cl-rich hydrothermal fluid of the deep reservoir by cold sea water at shallow levels. Geochemical analyses of the solid and liquid phases indicate that the hydrothermal fluids of the Tuzla geothermal system are in equilibrium with alteration products.The tectonic structure of the studied area is caused by NW–SE and NE–SW directional forces. The volcanic rocks where hydrothermal zones are observed in the studied area are of Lower–Middle Miocene age comprise latite, andesite, dacite, rhyolite-type lavas, tuff, and ignimbrites. 相似文献
25.
Ihsan Ketin 《International Journal of Earth Sciences》1948,36(1):77-83
Ohne Zusammenfassung 相似文献
26.
Ihsan Kaya Cengiz Kahraman 《Stochastic Environmental Research and Risk Assessment (SERRA)》2009,23(4):529-541
Air pollution is one of the most important threats for the humanity. It can damage not only human health but also Earth’s
ecosystem. Because of the harmful effects of air pollution, it should be controlled very carefully. To do the risk assessment
of air pollution in Istanbul, the process capability indices (PCIs) which are very effective statistics to summarize the performance
of process are used in this paper. Fuzzy PCIs are used to determine the levels of the air pollutants which are measured in
different nine stations in Istanbul. Robust PCIs (RPCIs) are used when air pollutants have correlation. Fuzzy set theory has
been applied for both PCIs and RPCIs to have more sensitive results. More flexible PCIs obtained by using fuzzy specification
limits and fuzzy standard deviation are used to evaluate the air pollution’s level of Istanbul. Additionally some evaluation
criteria have been constructed for fuzzy PCIs to interpret the air pollution. 相似文献
27.
Mohamed Ali Kalefa El-ghali Howri Mansurbeg Sadoon Morad Ihsan Al-Aasm George Ajdanlisky 《Sedimentary Geology》2006,190(1-4):299-321
Elucidation of diagenetic alterations in the Petrohan Terrigenous Group (fluvial; highstand systems tract HST) sandstones and Svidol Formation (tide-dominated deltaic and tidal flat, transgressive systems tract TST and highstand systems tract HST, respectively) sandstones and calcarenite, Lower Triassic, NW Bulgaria was constrained within a sequence stratigraphic framework. Eogenetic alterations in the fluvial HST sandstones include (i) formation of grain-coating infiltrated clays as a result of percolation of mud-rich surface waters into underlying coarse-grained and permeable channel-fills and crevasse splay sandstones; (ii) formation of pseudomatrix by mechanical compaction of mud intraclasts that were incorporated into the coarse-grained channel sandstones during their lateral avulsion; and (iii) cementation by calcite (δ18OVPDB = − 6.5‰ to − 3‰; δ13CVPDB = − 5.1‰ to + 0.6‰) and dolomite (δ18OVPDB = − 6.1‰ to − 0.3‰; δ13CVPDB = − 7.2‰ to − 5.8‰) in the crevasse splay and floodplain sediments. Mesogenetic alterations that are encountered in the fluvial HST sandstones include (i) illitization of grain-coating clays, mud intraclasts, and mica, possibly because of simultaneous albitization of feldspars; (ii) cementation by calcite (δ18OVPDB = − 14.5‰ to − 8.4‰; δ13CVPDB = − 7.7‰ to + 0.6‰) and dolomite (δ18OVPDB = − 15.8‰ to − 5‰; δ13CVPDB = − 7.9‰ to + 1.5‰); and (iii) limited amounts of quartz overgrowths in the channel sandstones owing to occurrence of thick grain-coating clays.
Conversely, the tide-dominated deltaic TST sandstones and the tidal flat HST calcarenite were pervasively cemented by calcite (δ18OVPDB = − 6.6‰ to − 3.1‰; δ13CVPDB = − 5.1‰ to + 0.6‰) and siderite (δ18OVPDB = − 7.2‰ to − 5.7‰; δ13CVPDB = + 0.3‰ to + 0.9‰) particularly below marine and maximum flooding surfaces, due to the presence of abundant bioclasts and prolonged residence time of the sediments under certain geochemical conditions along these surfaces. The remaining open pores were cemented during mesodiagenesis by calcite (δ18OVPDB = − 6.6‰ to − 3.1‰ and δ13CVPDB = − 5.1‰ to + 0.6‰) and dolomite (δ18OVPDB = − 6.6‰ to − 3.1‰ and δ13CVPDB = − 5.1‰ to + 0.6‰).
This study shows that constructing a conceptual model for the distribution of diagenetic alterations is possible by integration of diagenesis with sequence stratigraphy. The model shows that tide-dominated deltaic TST sandstones and tidal flat HST calcarenite were pervasively cemented by carbonates during near-surface eodiagenesis, owing to the presence of abundant bioclasts. Conversely, fluvial LST sandstones remained poorly cemented during near-surface eodiagenesis due to the lack of bioclasts, but were cemented by mesogenetic calcite, dolomite and quartz overgrowths instead. 相似文献
28.
Black and white dolomite crystals (mm to cm width) of different isotopic composition are associated with Triassic diapirism in central Tunisia, as well as with evaporite minerals and clays. The white dolomites occur mostly in the Jabal Hadifa diapir near the contact with Cretaceous limestones, whereas the smaller black dolomites occur in the Jabal Hamra diapir. The former dolomite has a narrow range of δ18O and δ13C values (− 3.83‰ to − 6.60‰ VPDB for δ18O; − 2.11‰ to − 2.83‰ VPDB for δ13C), whereas the latter dolomite has a wider range and more depleted values (− 4.92‰ to − 9.97‰ for δ18O; − 0.55‰ to − 6.08‰ for δ13C). However, the 87Sr / 86Sr ratios of most of the samples are near Triassic seawater values. Dolomite formation is due to at least two different fluids. The main fluid originated from deeper hydrothermal or basinal sources related to the Triassic saliferous rocks and ascended through faults during the diapiric intrusion. The second, less important fluid source is related to meteoric water originating from Cretaceous rocks. 相似文献
29.
Several researchers have suggested that upward and lateral hydrothermal fluid flow was responsible for dolomitization of various Devonian and Mississippian reservoirs in the Western Canada Sedimentary Basin (WCSB) based on sedimentological, geochemical and diagenetic evidence. In this study, a numerical model was applied to investigate hydrothermal fluid flow in the Wabamun Group, Parkland field, northeastern British Columbia, Canada. Our numerical results indicate that faults play the most critical role in controlling hydrothermal fluid flow. They provide a pathway connecting the basement of the basin and overlying sedimentary layers. Upwelling fluid flow via faults may bring reactants and heat from underlying strata to shallow formations for diagenetic reactions (e.g. dolomitization and/or chertification) or forming ore deposits. Salinity distribution of formation water, permeability configuration of host rock and regional fluid flow are also important factors affecting hot and brine fluid flow and accompanying heat and mass distribution. 相似文献