No description available.

An investigation of shale pore structure and compositional/geochemical heterogeneities has been undertaken to elucidate the controls upon gas capacities of potential shale gas reservoirs in northeastern British Columbia, western Canada. Methane sorption isotherms, pore structure and surface area data indicate a complex interrelationship of total organic carbon (TOC) content, mineral matter and thermal maturity affect gas sorption characteristics of Devonian-€”Mississippian (D-€”M) and Jurassic strata. Methane and carbon dioxide sorption capacities of D-€”M shales increase with TOC content, due to the microporous nature of the organic matter. Clay mineral phases arealso capable of sorbing gas to their internal structure; hence D-€”M shales which are both TOC- and clay-rich have the largest micropore volumes and sorption capacities on a dry basis. Jurassic shales, which are invariably less thermally mature than D-€”M shales, do not have micropore volumes which correlate with TOC. The covariance of methane sorption capacity with TOC, independent of micropore volume, indicates a solute gas contribution (within matrix bituminite) to the total gas capacity. On a wt% TOC basis, D-M shales sorb more gas than Jurassic shales: a result of thermal-maturation induced, structural transformation of the D-€”M organic fraction. Organic-rich D-€”M strata are considered to be excellent candidates for gas shales in Western Canada. These strata have TOC contents ranging between 1-5.7 wt%, thermal maturities into the dry-gas region, and thicknesses in places of over 1000 m. Total gas capacity estimates range between 60 and 600 bcf/section where a substantial percentage of the gas capacity is free gas, due to high reservoir temperatures and pressures. Inorganic material influences modal pore size, total porosity and sorption characteristics of D-M shales. Carbonate-rich samples often have lower organic carbon contents (oxic deposition) and porosity, hence potentially lower sorbed and free-gas capacities. Highly mature Devonian shales are both silica and TOC-rich (up to 85% quartz and 5 wt% TOC) and as such, deemed excellent potential shale gas reservoirs because they are both brittle (fracable), and gas-charged. However, quartz-rich Devonian shales display tight-rock characteristics, with poorly developed fabric, small median pore diameters and low permeabilities. Hence potential `frac-zones' will require an increased density of hydraulic fracture networks for optimum gas production.

A presente dissertação aborda questões relacionadas aos fósseis de lingulídeos da Sucessão devoniana da Bacia do Paraná, região dos Campos Gerais, PR, Brasil. Para a construção da análise tafonômica básica adotou-se metodologia de coleta de alta resolução, contando com um total de valvas de aproximadamente 2.300. Aspectos referentes à biologia e ecologia de lingulídeos atuais foram levantados e descritos em conjunto a considerações relativas aos fósseis. Realizou-se análise de composição química (EDS) de rochas e de valvas, na intenção de se obter os tipos de fossilização ocorrentes, que resultou na confirmação de fossilização na forma de moldes, impressões e substituições. Na análise tafonômica básica foi possível constatar a ocorrência de morte catastrófica; são raras as ocorrências de lingulídeos em aparente posição de vida; valvas inteiras e fragmentadas foram preservadas; dúvidas permanecem em relação ao grau de autoctonia / aloctonia dos bioclastos; na comparação entre a quantidade de lingulídeos ocorrentes em diferentes afloramentos observou-se a ausência de representantes da Província Malvinocáfrica, quando da abundância de lingulídeos. / The present paper approaches questions related to fossil lingulides that are present in de Devonian Sucession of the Paraná Basin, Campos Gerais region, Paraná state, Brazil. For the construction of the basic taphonomic analysis, approximately 2.300 fossil valves were collected, with a methodology of high resolution. Aspects related to the biology and ecology of extant lingulides were described associated with conjectures about the fossils. An analysis of chemical composition (EDS) was made on the rocks and valves, to know the type of fossilization that occurred on the material; from this analysis resulted the following types: molds, impressions and substituitions. The basic taphonomic analysis showed the following assertions: the occurrence of catastrophic death; that the occurrences of lingulids in life position are rare; the occurrence of valves completes and also fragments; none decisive conclusions were made about de degrees of autoctony / aloctony of the fossils. On the comparison between different outcrops, was noted an absence of Malvinokaffric representants when the lingulids were present in abundance.

A presente dissertação aborda questões relacionadas aos fósseis de lingulídeos da Sucessão devoniana da Bacia do Paraná, região dos Campos Gerais, PR, Brasil. Para a construção da análise tafonômica básica adotou-se metodologia de coleta de alta resolução, contando com um total de valvas de aproximadamente 2.300. Aspectos referentes à biologia e ecologia de lingulídeos atuais foram levantados e descritos em conjunto a considerações relativas aos fósseis. Realizou-se análise de composição química (EDS) de rochas e de valvas, na intenção de se obter os tipos de fossilização ocorrentes, que resultou na confirmação de fossilização na forma de moldes, impressões e substituições. Na análise tafonômica básica foi possível constatar a ocorrência de morte catastrófica; são raras as ocorrências de lingulídeos em aparente posição de vida; valvas inteiras e fragmentadas foram preservadas; dúvidas permanecem em relação ao grau de autoctonia / aloctonia dos bioclastos; na comparação entre a quantidade de lingulídeos ocorrentes em diferentes afloramentos observou-se a ausência de representantes da Província Malvinocáfrica, quando da abundância de lingulídeos. / The present paper approaches questions related to fossil lingulides that are present in de Devonian Sucession of the Paraná Basin, Campos Gerais region, Paraná state, Brazil. For the construction of the basic taphonomic analysis, approximately 2.300 fossil valves were collected, with a methodology of high resolution. Aspects related to the biology and ecology of extant lingulides were described associated with conjectures about the fossils. An analysis of chemical composition (EDS) was made on the rocks and valves, to know the type of fossilization that occurred on the material; from this analysis resulted the following types: molds, impressions and substituitions. The basic taphonomic analysis showed the following assertions: the occurrence of catastrophic death; that the occurrences of lingulids in life position are rare; the occurrence of valves completes and also fragments; none decisive conclusions were made about de degrees of autoctony / aloctony of the fossils. On the comparison between different outcrops, was noted an absence of Malvinokaffric representants when the lingulids were present in abundance.

A presente dissertação aborda questões relacionadas aos fósseis de lingulídeos da Sucessão devoniana da Bacia do Paraná, região dos Campos Gerais, PR, Brasil. Para a construção da análise tafonômica básica adotou-se metodologia de coleta de alta resolução, contando com um total de valvas de aproximadamente 2.300. Aspectos referentes à biologia e ecologia de lingulídeos atuais foram levantados e descritos em conjunto a considerações relativas aos fósseis. Realizou-se análise de composição química (EDS) de rochas e de valvas, na intenção de se obter os tipos de fossilização ocorrentes, que resultou na confirmação de fossilização na forma de moldes, impressões e substituições. Na análise tafonômica básica foi possível constatar a ocorrência de morte catastrófica; são raras as ocorrências de lingulídeos em aparente posição de vida; valvas inteiras e fragmentadas foram preservadas; dúvidas permanecem em relação ao grau de autoctonia / aloctonia dos bioclastos; na comparação entre a quantidade de lingulídeos ocorrentes em diferentes afloramentos observou-se a ausência de representantes da Província Malvinocáfrica, quando da abundância de lingulídeos. / The present paper approaches questions related to fossil lingulides that are present in de Devonian Sucession of the Paraná Basin, Campos Gerais region, Paraná state, Brazil. For the construction of the basic taphonomic analysis, approximately 2.300 fossil valves were collected, with a methodology of high resolution. Aspects related to the biology and ecology of extant lingulides were described associated with conjectures about the fossils. An analysis of chemical composition (EDS) was made on the rocks and valves, to know the type of fossilization that occurred on the material; from this analysis resulted the following types: molds, impressions and substituitions. The basic taphonomic analysis showed the following assertions: the occurrence of catastrophic death; that the occurrences of lingulids in life position are rare; the occurrence of valves completes and also fragments; none decisive conclusions were made about de degrees of autoctony / aloctony of the fossils. On the comparison between different outcrops, was noted an absence of Malvinokaffric representants when the lingulids were present in abundance.

Apesar do grande número de estudosenvolvendo taxonomia esistemática de braquiópodes, poucos foramos estudos que utilizassema metodologia de análise cladística. Desta forma,no estudo aqui apresentado, foi feita uma análise cladística dos taxabasais da Ordem Spiriferida, comatenção especialà superfamília Delthyridoidea. Esta superfamília, Siluro-Devoniano, temcomointegrante o taxon Australospirifer, representante típico do Domínio Malvinocáfrico, e presente no Devoniano brasileiro. A análise cladística tambémtem por objetivo testar a hipótese filogenética apresentada por Lespèrance e Bizarro (1999) para a superfamília Delthyridoidea. Braquiópodes, bivalves, tentaculítideos e trilobitas, típicos representantes do Província Malvinocáfrica, foram descritos para o flanco norte da Formação Ponta Grossa (Eo-mesodevoniano), Estado de Goiás, Brasil, uma área compoucos estudos paleontológicos. Foi descrita uma nova espécie para o gênero Ptychopteria, e umnovo gênero e nova espécie de espiriferídeo, comafinidades filogenéticas ao gênero Australospirifer. A análise cladística foi realizada com enraizamento a posteriori no taxon Eospirifer.O cladograma semiestrito resultante, escolhido como proposta detrabalho, apresentou CI=0,40, RI=0,70, RC=0,30. Apesar da baixa resolução, este estudo aqui discutido apresenta uma acuidade maior emrelação ao anteriormente realizado por Lespèrance e Bizarro (1999), principalmente por conter um maior número de caracteres e taxa.Como resultado, pôde ser observado que alguns grupos tradicionalmente considerados basais emSpiriferida, como Delthyridoidea e Cyrtioidea não são considerados monofiléticos. Por outro lado Reticularioidea e Martinioidea (excluindo Tenellodermis) são confirmados comogrupos monofiléticos. Além disso, o gênero Australospiriferé considerado um metataxon, sendo basal emrelação a um grupo inteiro, que corresponde tanto a taxatípicos do Hemisfério Norte quanto ao taxonnovo aqui descrito. / Despite the large number of taxonomic studies on fossil brachiopods, few include cladistic analysis. This study is one of the first to apply thismethod to basal taxa amongs Spiriferida, with special attention to the superfamily Delthyridoidea. This superfamily, restricted to the Silurian and Devonian, includes the taxon Australospirifer, which is common in Devonian deposits of Brazil and representative of the Malvinocafric Realm. This analysis also tests the phylogenetichypothesis proposed by Lespèrance and Bizarro (1999) for the superfamily Delthyridoidea. Brachiopods, bivalves, tentaculitids and trilobites, typical elements of the Malvinocafric Realm,are describedfrom the Ponta Grossa Formation (Early to Middle Devonian) in the northern portion of the Parana Basin in the State of Goiás, Brazil, a region still poorly known paleontologically, especially for brachiopods, when compared to the southern portion of the basin. A new species ofthe genus Ptychopteria,and a new genus and species ofspiriferidhaving phylogenetic affinities with the genus Australospiriferare described. The cladistic analysis was carriedout with a posteriorirooting in the taxon Eospirifer. The resulting semistrict cladogram, the preferred working hypothesis, presented CI=0,40, RI=0,70 and RC=0,30. Despite its relatively low topological resolution, this cladogrampresents greater accuracy than that proposed by Lespèrance and Bizarro (1999), mainly because of the greater number of characters, and taxa utilized. As a result,some groups, traditionally considered as basal within the Spiriferida, such as Delthyridoidea and Cyrtioidea, can not be interpreted here as monophyletic. On the other hand, Reticularioidea and Martinioidea (excluding Tenellodermis) are confirmed as monophyletics groups. In addition, the genus Australospirifer is considered a metataxon, and basal not only to the group including typical Northern Hemisphere taxa but also to the new genus and species described here.

M.Sc. / The Lower Devonian Bokkeveld Group is the Middle unit of the tripartite Cape Supergroup, which outcrops along the western, southern and eastern coastline of South Africa. A well-established sedimentary and stratigraphic understanding of the Bokkeveld Group allowed for geochemical and geochronological investigation in order to gain insight into the provenance characteristics, as well as the paleotectonic environment of the provenance areas. In order to observe any changes within the Bokkeveld Basin, complete profiles for geochemical investigation were sampled in the western, southern and eastern parts of the basin, and compared. Major and trace element patterns suggest that the western part of the basin received detrital input from felsic, magmatically evolved, and possibly alkaline sources, and that the sediment was highly recycled before deposition. Furthermore, the geochemistry suggests that the western part of the basin experienced “passive margin” type sedimentation. The geochemistry of the southern basin, in contrast, suggests input from less evolved, non-alkaline sources, and predicts sedimentation under “active margin” conditions for the lower part of the group. The eastern basin is geochemically intermediate between the western and southern basins. Zircon populations for the three parts of the basin further suggest that sources of different ages fed the three parts of the basin. The zircon population of the western basin suggests that the Namaqua Natal Belt (Mesoproterozoic) and Neoproterozoic cover successions were the major source of detritus, with only minor input from Paleozoic sources. The eastern basin also appears to have sourced mainly Namaquan aged material as well as Neoproterozoic material, with no Paleozoic input. The southern basin has a remarkably different zircon population, with the majority of grains being Paleozoic in age, and only a few Neoproterozoic and Mesoproterozoic grains. Furthermore, many of the grains are younger than any known source-rocks on the Kalahari Craton, and thus allude to input from an extra-Kalahari source into the southern part of the basin. The youngest grain from the southern basin overlaps with the established depositional age of the Bokkeveld Group, suggesting some syn-depositional or briefly pre-depositional magmatic activity in the source area(s) of the southern basin, as predicted by the geochemistry. The complete lack of zircon ages older than the Namaqua Natal Belt (Mesoproterozoic), would suggest that the Archean to Paleoproterozoic inner part of the Kalahari Craton, the Kaapvaal Craton, was not sourced by the Bokkeveld Group. This is most likely due to the Namaqua Natal Belt having served as a large east-west trending morphological divide during Bokkeveld deposition, preventing transport of detritus from the craton interior. Remarkably, this would suggest that the Namaqua Natal Mountain Range must have survived erosion and persisted as a morphological boundary for ca. 600 Ma to serve as the major source of detritus for the Bokkeveld Group. Even an extensive, craton-fringing sedimentary cover-succession such as the Bokkeveld Group, may thus not provide a “detrital fingerprint” of the craton interior, and paleogeographical implications must be taken into consideration during provenance studies. Paleocurrent directions for the Bokkeveld Group indicate a west to east transport direction in the southern part of the basin, and as such, a western, extra-Kalahari source, most likely the Rio de La Plata Craton and surrounds, is expected to have been the source of both the young Paleozoic zircons, as well as undifferentiated material as revealed in the geochemistry.

No description available.

No description available.

An investigation of shale pore structure and compositional/geochemical heterogeneities has been undertaken to elucidate the controls upon gas capacities of potential shale gas reservoirs in northeastern British Columbia, western Canada. Methane sorption isotherms, pore structure and surface area data indicate a complex interrelationship of total organic carbon (TOC) content, mineral matter and thermal maturity affect gas sorption characteristics of Devonian- Mississippian (D- M) and Jurassic strata. Methane and carbon dioxide sorption capacities of D- M shales increase with TOC content, due to the microporous nature of the organic matter. Clay mineral phases arealso capable of sorbing gas to their internal structure; hence D- M shales which are both TOC- and clay-rich have the largest micropore volumes and sorption capacities on a dry basis. Jurassic shales, which are invariably less thermally mature than D- M shales, do not have micropore volumes which correlate with TOC. The covariance of methane sorption capacity with TOC, independent of micropore volume, indicates a solute gas contribution (within matrix bituminite) to the total gas capacity. On a wt% TOC basis, D-M shales sorb more gas than Jurassic shales: a result of thermal-maturation induced, structural transformation of the D- M organic fraction. Organic-rich D- M strata are considered to be excellent candidates for gas shales in Western Canada. These strata have TOC contents ranging between 1-5.7 wt%, thermal maturities into the dry-gas region, and thicknesses in places of over 1000 m. Total gas capacity estimates range between 60 and 600 bcf/section where a substantial percentage of the gas capacity is free gas, due to high reservoir temperatures and pressures. Inorganic material influences modal pore size, total porosity and sorption characteristics of D-M shales. Carbonate-rich samples often have lower organic carbon contents (oxic deposition) and porosity, hence potentially lower sorbed and free-gas capacities. Highly mature Devonian shales are both silica and TOC-rich (up to 85% quartz and 5 wt% TOC) and as such, deemed excellent potential shale gas reservoirs because they are both brittle (fracable), and gas-charged. However, quartz-rich Devonian shales display tight-rock characteristics, with poorly developed fabric, small median pore diameters and low permeabilities. Hence potential `frac-zones' will require an increased density of hydraulic fracture networks for optimum gas production. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate