Maps in pocket inside back cover. / Includes published papers and abstracts of works by the author / "November 2003" / Includes bibliographical references. / Various paging : ill. (chiefly col.), maps, plates, charts (some folded) ; 30 cm. + 2 scaled seismic survey maps / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, School of Earth and Environmental Sciences, National Centre for Petroleum Geology and Geophysics and Discipline of Geology and Geophysics, 2004

The study uses subsidence analysis of three deep wells to basement combined with sequence stratigraphic mapping to show that a 85,000 km² area of the Eastern Venezuelan foreland basin in the region of the Orinoco Delta underwent three main stages of foreland-related subsidence that followed a protracted Cretaceous - late Oligocene period of precollisional, passive margin formation. Phase 1 consists of increased foreland basin subsidence in the late Oligocene to middle Miocene (23 - 13 Ma) at average sedimentation rates of 0.14 mm/yr. Clastic rocks of Phase 1 include the Freites Formation, a 1.2 km-thick section of greenish-gray fissile shale and shaly sandstone deposited in shallow marine- neritic environments. Seismic facies show progradation of Phase 1 clastic rocks as a wedge from the NE and NNE. Clastic rocks deposited during the accelerated Phase 2 in the middle to late Miocene (13 -11 Ma at sedimentation rates of 1.45 mm/yr) include the La Pica Formation, a 2.7 km-thick section of gray silt and fine-grained sandstone deposited in shallow marine/coastal proximal environments. Seismic facies show progradation of Phase 2 clastic rocks as a wedge to the northeast. Phase 3 consists of decelerating foreland basin subsidence in the period of late Miocene-mid Pliocene (11-6 Ma at average sedimentation rates of 0.86 mm/yr). Sedimentary rocks deposited during this period include the Las Piedras Formation, a 1.45 km-thick section of sandstone, carbonaceous siltstone and shale deposited in deltaic environments. Seismic facies show a progradation of Phase 3 clastic rocks as a wedge to the northeast and east-northeast. Deeper marine environments and more rapid subsidence rates of Phases 1 and 2 are interpreted as an underfilled foreland basin controlled by active thrusting along the Serrania del Interior at the northern flank of the basin. Deltaic environments and slower rates of Phase 3 are interpreted as an overfilled foreland related to rapid seaward progradation of the Orinoco Delta and its filling of the former, dynamically- maintained interior seaway. Paleogeographic maps constrained by wells and seismic lines show a large regression of the Orinoco River towards the west across the Columbus basin and Eastern Venezuelan basin during the late Miocene and the Paleocene. In this foreland basin setting, the effects of thrust-related tectonic subsidence and early deposition of the Orinoco Delta play a larger role in the early Miocene-Pleistocene sequences than eustatic effects. / text

The Early Permian coal samples for the study were obtained from the Vasse Shelf, southern Perth Basin, located approximately 200 km south- west of Perth. The selected coal samples for the study were also obtained from the Premier Sub-basin of the Collie Basin and the Irwin Sub-basin of the Perth Basin. The Early Permian coal measures are described as the Sue Coal Measures from the Vasse Shelf, the Ewington Coal Measures from the Premier Sub-basin and the coal measures from the Irwin sub-basin are described as the Irwin River Coal Measures.The Vasse Shelf coal is finely banded and the dominant lithotypes are dull and dull banded types, followed by bright banded and banded types, with minor bright types. The variation of dull and bright lithotypes represents fluctuating conditions of water table level during the growth of peat in the swamp. The maceral composition of the coal is predominantly composed of inertinite, followed by vitrinite and minor exinite and mineral matter. The coal is characterized by very low to medium semifusinite ratio and medium to high vitrinite content, supporting the deposition in anaerobic wet conditions with some degree of oxidation. The coal is classified as sub- bituminous to high volatile bituminous of the Australian classification. In terms of microlithotype group, the predominance of inertite over vitrite suggests the coal was formed under drier conditions with high degree of oxidation during its deposition. On the basis of the interpretations of lithotypes, macerals, microlithotypes and trace elements, the depositional environment of the coal is braided and meandering deltaic-river system without any brackish or marine influence.The maceral composition of the Collie coal predominantly consists of inertinite and vitrinite, with low exinite and mineral matter. The very low to low semifusinite ratio and low to medium vitrinite content of ++ / the coal indicate that the coal was formed under aerobic dry to wet conditions with some degree of oxidation. The coal is categorized as sub-bituminous according to the Australian classification. The domination of inertite and durite over vitrite and clarite contents in the coal reflects the deposition under drier conditions with fluctuations in the water table. On the basis of the interpretations of macerals, microlithotypes and trace elements distribution, the depositional environment of the coal is lacustrine, braided to meandering fluvial system, without the influence of any marine influx.The maceral composition of the Irwin River coal consists predominantly of vitrinite and inertinite, and minor exinite and mineral matter. The coal has very low semifusinite ratio and medium to high vitrinite content, suggesting the coal was deposited in anaerobic wet conditions with some degree of oxidation. The coal is classified as sub-bituminous of the Australian classification. The predominance of vitrite and clarite over inertite and durite contents in the coal indicates that the coal was formed in wetter conditions and in high water covers with a low degree of oxidation. Based on macerals and microlithotypes contents, the depositional environment of the coal is braided fluvial to deltaic, which is in accordance with the interpreted non- marine and mixed marine environment of deposition in the sub-basin.The petrological comparisons of Vasse Shelf, Collie and Irwin River coals show that the average vitrinite content of the Irwin River coal is highest (49.1%) and of the Collie coal is lowest (37.3%) of the three. The inertinite content is highest in Collie coal (49.1%), followed by Vasse Shelf (46.4%) and Irwin River (39.2%) coals. The exinite content is low in Irwin River coal (6.3%) as compared with Vasse Shelf (9.0°/,) and Collie (8.3%) coals. The mineral matter content ++ / is relatively low for all the three coals. The rank of the Vasse Shelf coal is high as compared with the Collie and Irwin River coals, either due to tectonic uplift after the deposition in post-Permian in the southern Perth Basin, or due to the average depth of burial over Vasse Shelf which is much greater than that of Collie and Irwin River coals.The comparisons of the coal from Western Australia with the selected Gondwana coals show that the predominance of inertinite over vitrinite occurs in the Western Australian coals (Vasse Shelf and Collie Basin). On the other hand, the Brazilian, eastern Australian, Indian and Western Australian (Irwin Sub-basin) coals are dominated by vitrinite over inertinite. The exinite content is highest in the Indian coals and lowest in the eastern Australian coals. The mineral matter content is highest in the Brazilian and Indian coals, and lowest in Western Australian (Vasse Shelf) and eastern Australian (Sydney Basin) coals. The rank of the coals ranges from sub- bituminous to medium volatile bituminous according to the Australian classification.

Regional exploration in the Barrow Sub-basin has dominantly focused on structural traps in the Top Barrow Group. A lack of recent discoveries has focused attention more towards the economic potential of the Early Cretaceous intra-Barrow Group plays. The aim of this study was to interpret the seismic sequence stratigraphy and depositional history of the intra-Barrow Group within the Barrow Sub-basin, with emphasis on the identification of stratigraphic traps and potential locations of economic seal/reservoir couplets within the study area. The study area lies south of Barrow Island, and contains the topsets, foresets and toesets of the ‘Barrow delta’, which are an amalgamation of Mesozoic sandprone fluvial, coastal deltaic and deepwater successions. The final stages of the break-up of Gondwana impacted on the structural development of the Barrow Sub-basin, when a large shelf-margin fluvial/deltaic system built out toward the north to northeast, contributing to northerly shelf margin accretion, with largescale clinoform features and associated depositional environments. The dataset comprises the Flinders 3D seismic survey 1267 km² and 35 well logs. Eleven seismic sequences are identified and a seismic sequence stratigraphic framework tied to the wells has been developed, via detailed sequence stratigraphic mapping, integrated with 3D visualisation techniques with the use of Petrel. These eleven second-order sequences are further subdivided into lowstand, transgressive and highstand systems tracts. The movement of the palaeo-shelf break, slope and base of slope can be traced throughout each sequence, displaying an overall trend of building out in a north to northeast direction. A series of palaeo- geographic maps for each sequence has been developed to illustrate the basin’s evolution. The seismic sequences identified display progradation, followed by aggradation, then downstepping, concluding with progradation and aggradation. A high-resolution sequence stratigraphic study of Seismic Sequence 1 showed that several higher-order sequences can be identified, including numerous lowstand systems wedges, along with associated channel features, which could be targeted as new plays. The sequence stratigraphic framework developed, palaeo-geographic reconstructions and all other interpretations made for this project have been integrated to assess the prospectivity of the intra-Barrow Group over the study area, resulting in the identification of a number of leads and prospectivity summaries for each of the 11 Seismic Sequences identified within the intra-Barrow Group. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1313353 / Thesis (M.Sc.(Petrol.G&G))-- University of Adelaide, Australian School of Petroleum, 2008

Regional exploration in the Barrow Sub-basin has dominantly focused on structural traps in the Top Barrow Group. A lack of recent discoveries has focused attention more towards the economic potential of the Early Cretaceous intra-Barrow Group plays. The aim of this study was to interpret the seismic sequence stratigraphy and depositional history of the intra-Barrow Group within the Barrow Sub-basin, with emphasis on the identification of stratigraphic traps and potential locations of economic seal/reservoir couplets within the study area. The study area lies south of Barrow Island, and contains the topsets, foresets and toesets of the ‘Barrow delta’, which are an amalgamation of Mesozoic sandprone fluvial, coastal deltaic and deepwater successions. The final stages of the break-up of Gondwana impacted on the structural development of the Barrow Sub-basin, when a large shelf-margin fluvial/deltaic system built out toward the north to northeast, contributing to northerly shelf margin accretion, with largescale clinoform features and associated depositional environments. The dataset comprises the Flinders 3D seismic survey 1267 km² and 35 well logs. Eleven seismic sequences are identified and a seismic sequence stratigraphic framework tied to the wells has been developed, via detailed sequence stratigraphic mapping, integrated with 3D visualisation techniques with the use of Petrel. These eleven second-order sequences are further subdivided into lowstand, transgressive and highstand systems tracts. The movement of the palaeo-shelf break, slope and base of slope can be traced throughout each sequence, displaying an overall trend of building out in a north to northeast direction. A series of palaeo- geographic maps for each sequence has been developed to illustrate the basin’s evolution. The seismic sequences identified display progradation, followed by aggradation, then downstepping, concluding with progradation and aggradation. A high-resolution sequence stratigraphic study of Seismic Sequence 1 showed that several higher-order sequences can be identified, including numerous lowstand systems wedges, along with associated channel features, which could be targeted as new plays. The sequence stratigraphic framework developed, palaeo-geographic reconstructions and all other interpretations made for this project have been integrated to assess the prospectivity of the intra-Barrow Group over the study area, resulting in the identification of a number of leads and prospectivity summaries for each of the 11 Seismic Sequences identified within the intra-Barrow Group. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1313353 / Thesis (M.Sc.(Petrol.G&G))-- University of Adelaide, Australian School of Petroleum, 2008

Title page, table of contents and abstract only. The complete thesis in print form is available from the University of Adelaide Library. / The occurrence of palaeo-oil columns in Late Jurassic and Cretaceous reservoirs in the Vulcan sub-basin indicates that hydrocarbon accumulations have leaked. It is unclear whether accumulations have leaked through breach of top seal or fault seal. This study evaluates the top seal potential for hydrocarbon accumulations in the Vulcan Sub-basin. For this purpose a top seal potential assessment methodology was developed. Seal potential (SP) combines seal capacity (the hydrocarbon column height that can physically be held back by seal), seal geometry (the areal extent and thickness of the seal) and seal integrity (rock mechanical properties of the seal). Seal capacities are measured using mercury injection capillary pressure calculations. Areal extent is evaluated using sedimentological and sequence stratigraphic principles. Thickness is determined empirically from well logs and seismic data. Seal integrity is derived from a brittleness index. In addition, a component relating to data quality and quantity is included in seal potential evaluation. The main sample set for this study is composed of drill cuttings. For this reason a comparison of seal capacity results measured from cuttings and cores has verified that cuttings samples provide accurate seal capacity measurements. Lower Vulcan Formation SP ranges from low to high due to variations in seal capacity and thickness risks as well as data quality and quantity. High SP occurs in the main depocentres and low SP occurs on the palaeo-highs and basin margins. Upper Vulcan Formations SP ranges from low to moderate due to variations in seal capacity. Moderate SP occurs in the depocentres and low SP on the basin margins. In the Echuca Shoals Formations seal capacity. Formation seal extent and integrity as well as data quality and quantity are good. However seal thickness is inconsistent, resulting in SP variations from good to poor as a function of thickness. Jamieson Formation has high seal capacities, is thick and areally extensive, however the seal potential is locally moderate (for example on the Ashmore Platform) due to seal integrity risk. SP for the Jamieson is controlled by the thickness and the amount of calcite present in the rock, which affects the brittleness of the formation and hence the seal integrity. The Woolaston, Gibson and Fenelon (WGF) Formations are grouped together as a regional seal and in this group SP varies from low to high. The WGF rocks generally have high seal capacities, are areally extensive and thick with good data quality and quantity sample set wise. Where the WGF is predominantly marl and calcilutite some of the highest brittleness index values were recorded and hence the WGF has a low SP in these areas. Based on the overall seal potential analysis, almost all seals in the area are capable of holding back hydrocarbon columns greater then present or palaeocolums recorded. This suggests that hydrocarbon leakage in the Vulcan Sub-Basin did not occur as a result of top seal capillary failure. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1313021 / Thesis (Ph.D.) -- University of Adelaide, Australian School of Petroleum, 2008

FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico / Este trabalho teve como objetivo avaliar as variÃveis fÃsicas, quÃmicas, biolÃgicas e a ocorrÃncia tanto da toxicidade aguda como da diversidade e quantidade da biomassa fitoplanctÃnica, ao longo de um ciclo climÃtico, na sub-bacia B1, integrante da bacia hidrogrÃfica do rio CocÃ, Fortaleza â CE. A amostragem ocorreu em frequÃncia mensal para os quatorzes pontos de coleta, no perÃodo de setembro de 2010 a abril de 2011, com a exceÃÃo de fevereiro de 2011, quando nÃo foi possÃvel executÃ-la. Os parÃmetros analisados, temperatura, transparÃncia, pH, turbidez, cor verdadeira, condutividade elÃtrica, sÃlidos e fraÃÃes, Ãleos e graxas, alcalinidade e fraÃÃes, dureza e fraÃÃes, cÃlcio, magnÃsio, oxigÃnio dissolvido, cloretos, DBO5, DQO, fÃsforo e fraÃÃes, sulfato, sulfeto, ferro total, clorofila âaâ, amÃnia total, nitrito, nitrato, nitrogÃnio orgÃnico, nitrogÃnio total kjeldahl, Coliformes Termotolerantes, Escherichia coli, toxicidade aguda, identificaÃÃo e contagem do fitoplÃncton, indicaram variaÃÃo no espaÃo devido aos diferentes impactos antrÃpicos sofridos. Toda a sub-bacia B1 encontra-se eutrofizada, principalmente devido ao lanÃamento de matÃria orgÃnica e nutrientes, especialmente o fÃsforo. Apesar do perÃodo monitorado apresentar quadra invernosa atÃpica, Ãndices pluviomÃtricos acima da mÃdia, isso nÃo foi suficiente para ocasionar a diluiÃÃo e possÃvel enquadramento legal, principalmente, com relaÃÃo aos teores de DBO5, Ãleos e graxas, fÃsforo total e Coliformes Termotolerantes. Na maior parte do monitoramento, a sub-bacia B1 apresentou indÃcios de toxicidade; somente no mÃs de abril foi evidenciada toxicidade aguda, o que pode ser devido à ocorrÃncia de chuvas no dia anterior à coleta. Com relaÃÃo à diversidade fitoplanctÃnica, no perÃodo seco houve a ocorrÃncia de 58 tÃxons e 7 classes; na quadra invernosa, houve o aumento da diversidade, 65 tÃxons e 10 classes. As classes que lideram os dois perÃodos sÃo: Chlorophyceae e Cyanobacteria. No entanto, Aphanocapsa spp à a classe dominante para os dois perÃodos, em todos os pontos monitorados, apresentando valores superiores ao limite estabelecido pela legislaÃÃo vigente, o que se torna preocupante, pois se trata de uma espÃcie potencialmente tÃxica. / This study aimed to evaluate the physical, chemical, biological, and the occurrence of both the acute toxicity and the diversity and quantity of phytoplankton biomass, along a climatic cycle, on sub-basin B1, a member of the Cocà River basin, Fortaleza - CE. The sampling occurred monthly on fourteen collecting points in the period of September 2010 to April 2011, in the exception of February 2011 that could not run it. With the parameters analyzed, temperature, transparency, pH, turbidity, true color, conductivity electrical, solids and fractions, calcium, magnesium, dissolved oxygen, chlorides, BOD5, QOD, phosphorus and fractions, sulfate, sulfide, total iron, Chlorophyll "a", total ammonia, nitrite, nitrate, organic nitrogen, total kjeldahl nitrogen, thermotolerant coliforms, Escherichia coli, acute toxicity, identification and enumeration of phytoplankton, have indicated variation in space due to different human impacts suffered. All the sub-basin B1 is found eutrophic, mainly due to the release of organic matter and nutrients, especially phosphorus. Although the monitored period to present court wintry atypical, with above the average rainfall, it was not enough to cause the dilution and possible legal framework, mainly at the oil and grease, total phosphorus and thermotolerant coliforms. In most of the monitoring, the sub-basin B1 showed signs of toxicity; only in the month of April was observed acute toxicity, which may be due to the rainfall some days before collection. With respect to phytoplanktonic diversity during the dry season to occurred the presence of 58 taxon and 7 classes and at court wintry, diversity increases to taxon 65 and 10 classes. The classes who lead both periods are: Chlorophyceae e Cyanobacteria. However, Aphanocapsa spp is the dominant class in both periods, at all points monitored, with values above the limit set by law, which is very worrying, because it is a potentially toxic species.

Submitted by JÚLIO HEBER SILVA (julioheber@yahoo.com.br) on 2017-03-17T17:48:27Z No. of bitstreams: 2 Tese - Mariana Nascimento Siqueira - 2016.pdf: 4136078 bytes, checksum: 45863950dcc863dc639c8228c08c9584 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2017-03-20T13:42:35Z (GMT) No. of bitstreams: 2 Tese - Mariana Nascimento Siqueira - 2016.pdf: 4136078 bytes, checksum: 45863950dcc863dc639c8228c08c9584 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-03-20T13:42:35Z (GMT). No. of bitstreams: 2 Tese - Mariana Nascimento Siqueira - 2016.pdf: 4136078 bytes, checksum: 45863950dcc863dc639c8228c08c9584 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-03-08 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / Anthropogenic changes have changed land cover patterns and caused fragmentation of ecosystems. These changes have several consequences for biodiversity, such as habitat loss and isolation, creation of anthropic matrix, and edge effect. Few studies have evaluated the effects of fragmentation in the Cerrado, especially the effects on vegetation structure and abiotic attributes of savanna formations. Here, we sampled 17 fragments of Dense Cerrado in the Upper Rio Araguaia basin, which is a highly fragmented area. Specifically, we compared the more altered Sub-basin of the Rio Claro with the more conserved Sub-basin Rio Garças. Fragments had the fragile Quartzipsamment soils. All fragments were larger than 50 ha and had pasture matrix. Specifically, we asked the following questions: 1) What is the percentage of area lost by fragments in the last 30 years? 2) How area loss influence the woody plant community structure? 3) The species composition similarity decreases with geographical distance between fragments? 4) The edge-interior gradient affects the woody plant community structure? 5) How microclimate and physico-chemical variables vary along an edgeinterior gradient? 6) The community structure of woody plants is influenced by microclimate and physico-chemical characteristics of the soil? We sampled all woody plants with diameter ground higher than 30 cm or equal to 5 cm, in three 20 x 50 m plots along a edge-interior gradient in each fragment. We collected soils between 0 to 20 cm deep in all plots and the matrix. The air and soil temperatures, air humidity, altitude, geographical position, and light intensity were collected along with soil samples. We recorded 8,749 woody plants, belonging to 131 species. Fragment area was significantly reduced between 1985 and 2013, but the historical and current area were not associated with community structure and species diversity. We also did not find a correlation between compositional similarity and geographic distance between fragments. Additionally, 2,877 individuals of 116 species occurred at the edge, 3,038 individuals of 110 species occurred at intermediate environments, and 2,995 individuals of 107 species occurred in the center of fragments. However, species composition and community structure did not differ along the edge-interior gradient. Also, abiotic variables did not differ along the matrix-edge-interior gradient. However, these variables differed between the two sub-basins. The Rio Claro Sub-basin had higher values of Ca/CTC and xiii Ca/K, which are related to nutrient availability in the soil. The spatial distribution of plant species was influenced by altitude, humidity, silt, organic matter, pH, and calcium. / As mudanças antrópicas na cobertura do solo têm ocasionado um processo denominado fragmentação de ecossistemas, que geram consequências diversas para a biodiversidade como perda, isolamento e forma do habitat, matriz antrópica, efeito de borda e outras interferências antrópicas. Poucos estudos avaliando efeitos da fragmentação ocorreram em áreas de Cerrado, especialmente avaliando consequências na estrutura da vegetação de formações savânicas e os atributos abióticos. Com o objetivo de preencher essas lacunas, a presente pesquisa selecionou 17 fragmentos de Cerrado Denso na Alta Bacia do Rio Araguaia, que representa bem os processos de fragmentação antrópica no Cerrado. Optou-se pela Sub-bacia mais degradada e pela mais conservada, a Sub-bacia do Rio Claro e Sub-bacia do Rio Garças, respectivamente. Os fragmentos foram selecionados sobre Neossolos Quartzarênicos, solos considerados frágeis do ponto de vista ambiental. A matriz de todos os fragmentos foi a pastagem e todos eles apresentavam área superior à 50 ha. Para a área de estudo, buscou-se responder as seguintes questões: 1) Qual a porcentagem de área perdida pelos fragmentos de Cerrado Denso ao longo dos últimos 30 anos? 2) Como a perda de área pode influenciar a estrutura da comunidade de planta lenhosa em fragmentos de Cerrado Denso? 3) A similaridade de espécies diminui com o aumento da distância geográfica entre os fragmentos amostrados? 4) O gradiente borda-interior afeta a estrutura da comunidade de plantas lenhosas? 5) Como se comportam as variáveis microclimáticas e físicoquímicas do solo ao longo de um gradiente borda-interior? 6) A estrutura da comunidade de plantas lenhosa é influenciada pelas características microclimáticas e físico-químicas do solo? Diante dessas questões, foram coletadas amostras da vegetação lenhosa através do método de parcelas de 20 x 50 m, em três ambientes distintos de cada fragmento (ambiente de borda, intermediário e central), incluindo todos os indivíduos lenhosos com diâmetro a 30 cm do solo maior ou igual a 5 cm. Os solos foram coletados em todas as parcelas e na pastagem para análise físico-química. A temperatura do ar, do solo, umidade relativa do ar, altitude, posição geográfica e intensidade luminosa foram coletadas no ponto de coleta de solos. Como resultados, registrou-se 8.749 indivíduos lenhosos, distribuídos em 131 espécies nos 17 fragmentos. Observou-se que a área dos fragmentos estudados reduziu significativamente entre os anos de 1985 e 2013, mas a perda histórica de área dos fragmentos e a área atual não apresentaram relação com a estrutura da comunidade lenhosa e a diversidade de xi espécies. Também não foi observada uma correlação entre a similaridade de espécies e a distância entre os fragmentos amostrados. Adicionalmente, constatou-se que dos espécimes amostrados, 2877 indivíduos em 116 espécies eram de ambiente de borda, 3038 indivíduos em 110 espécies de ambiente intermediário e 2995 indivíduos em 107 espécies do centro dos fragmentos. No entanto, não foram encontradas alterações na composição e estrutura da comunidade lenhosa ao longo do gradiente borda-interior. As variáveis abióticas não diferiram ao longo do gradiente pasto-borda-interior nos fragmentos analisados. Entretanto, estas variáveis diferiram entre as duas Sub-bacias amostradas, em que a Sub-bacia do rio Claro apresentou os maiores valores de Ca/CTC e Ca/K, relacionadas com a disponibilidade de nutrientes no solo. Também registrou-se que a distribuição espacial de espécies vegetais foi influenciada por variáveis abióticas, como altitude, umidade, silte, matéria orgânica, pH e cálcio.

The Gemsbok Sub-basin is situated in the south-western corner of the Kalahari Karoo Basin and extends south from the Kgalagadi District of Botswana into the Northern Cape (South Africa); and west into the Aranos Basin (southeast Namibia). The Sub-basin preserves a heterogeneous succession of Upper Palaeozoic to Lower Mesozoic sedimentary and volcanic rocks of the Karoo Supergroup. Because the succession is largely covered by the Cenozoic Kalahari Group, the stratigraphy of the succession is not as well understood as the Main Karoo Basin in South Africa. Most research in the Gemsbok Sub-basin is based on borehole data. This study focuses on the intrabasinal correlation, depositional environments and provenance of the Karoo Supergroup in the Gemsbok Sub-basin in Botswana and Namibia. Based on detailed sedimentological analyses of 11 borehole cores of the Karoo Supergroup in the Gemsbok Sub-basin of Botswana and Namibia, 8 facies associations (FAs) comprising 14 lithofacies and 2 trace fossil assemblages (Cruziana and Skolithos ichnofacies) were identified. The facies associations (FA1 to FA8) correspond to the lithostratigraphic subdivisions (the Dwyka Group, Ecca Group, Beaufort equivalent Group, Lebung Group [Mosolotsane and Ntane formations] and Neu Loore Formation) of the Karoo Supergroup. Sedimentological characteristics of the identified facies associations indicate the following depositional environments: glaciomarine or glaciolacustrine (FA1, Dwyka Group), deep-water (lake or sea) (FA2, Ecca Group), prodelta (FA3, Ecca Group), delta front (FA4, Ecca Group), delta plain (FA5, Ecca Group), floodplain (probably shallow lakes) (FA6, Beaufort Group equivalent), fluvial (FA7, Mosolotsane and Neu Loore formations) and aeolian (FA8, Ntane Sandstone Formation). The Dwyka Group (FA1) forms the base of the Karoo Supergroup in the Gemsbok Subbasin and overlain by the Ecca Group deposits. Three types of deltas exist within the Ecca Group: fluvial-dominated; fluvial-wave interaction and wave-dominated deltas. The Gemsbok Sub-basin was characterised by rapid uplift and subsidence and high sediment influx during the deposition of the Ecca Group. Petrographic and geochemical analyses of the Ecca Group sandstones revealed immature arkose and subarkose type sandstones dominated by angular to subangular detrital grains, sourced from transitional continental and basement uplifted source areas. The sandstones of Ntane Sandstone Formation are classified as subarkoses and sourced from the craton interior provenances.

A chronostratigraphic subdivision of the Upper Jurassic synrift sediments in the eastern Barrow Sub-basin was developed from the integration of core logging, petrography, well log sequence analyses and seismic stratigraphy. From this basis, the Callovian to base Cretaceous sediments may be subdivided into five depositional sequences. The development of the sequence boundaries, in most part, is closely related to periods of major changes in basin configuration associated with the sequential breakup of eastern Gondwanaland. Initiation of the Upper Jurassic rift complex occurred during late Callovian early Oxfordian associated with the development of a northeast-southwest trending spreading centre on the Argo Abyssal Plain. The spreading centre propagated southwards during the Late Jurassic. This resulted in active rifting in the Barrow Sub-basin and ultimately led to the separation of the Indian and Australian plates during Valanginian time.Upper Jurassic synrift sediments in the eastern Barrow Sub-basin consist of detached basin floor fan complexes, channelised and canyon fed fan systems, slump deposits, prograding outer shelfal to slope deposits and deep marine claystones. Post-depositional uplift of the eastern shelfal areas during the Late Jurassic resulted in erosion of the transgressive and highstand fluvial-deltaic to shelfal deposits. These periods of uplift and erosion provided much of the sediment redeposited in the basinal areas during the lowstand periods. Seven sandstone facies were recognised in the Upper Jurassic sedimentary section based on core control. Each sandstone has unique reservoir characteristics which can be related to the depositional setting. / The abundance of glauconite and belemnites combined with ichnology and biostratigraphic assemblages associated with marine environments, indicate that deposition of all the sandstone facies occurred within an outer shelfal - deep marine environment. Reservoir quality was best developed in the dominantly medium grained, moderate - well sorted sandstones, (facies 7), which were deposited as detached, basin floor submarine fan sands or interbedded turbidites. In contrast, reservoir quality was relatively poorly developed in the remaining facies which were deposited as slope fans, slumps, or distal turbidite deposits.The abundance of quartz and presence of banded iron, jasper, and potassic feldspar grains support the provenance for the basinal sandstone facies being the Precambrian alkyl granites and banded iron formation of.the Pilbara Shield and Hammersley Ranges. These Precambrian igneous rocks and metasediments mark the eastern boundary of the Barrow Sub-basin study area. To predict the distribution of sedimentary facies in the Upper Jurassic synrift sediments of the eastern Barrow Sub-basin, the interplay between the major controlling depositional processes, namely tectonics, sediment supply and eustasy must be understood. Subdivision of the synrift sedimentary section on the basis of lithostratigraphy can be misleading and does not adequately resolve the facies relationships observed in the well intersection. The results of this research form the basis for a regional sequence analysis and seismic stratigraphic study.