The Cleveland Shale displays a characteristic and distinctive pattern of promontories and recessed intervals on weathered outcrops, which appears to represent cyclicity. This weathering pattern can be observed in other shales, both within and outside the Appalachian Basin; so determining the nature of these cycles may be critical for understanding the origin of, not only the Cleveland Shale, but also of black shales in general. Cyclicity in the Cleveland was examined on a decimeter-to-meter scale using lithologic characterization, gamma-ray stratigraphy and x-ray fluorescence, and on a millimeter-to-centimeter scale using organic petrography. Lithologic characterization and gamma-ray stratigraphy revealed Milankovitch-band fourth- and fifth-order cyclicity related to changes in the earth’s orbital eccentricity (100 ka) and obliquity of the earth’s axis (42 ka), respectively. Sedimentological changes associated with these cycles were identified through organic petrography and x-ray fluorescence. A depositional model was developed from these data sets, which suggests that cyclic changes in local climate — from cold and wet to warm and dry — controlled advancing and retreating glaciation in the adjacent Acadian mountains as well as concomitant sea-level rise and fall in the Black-Shale Sea. Such changes would have controlled sediment influx to the sea and are thought to be reflected in the cycles.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O presente estudo baseou-se na análise das variações verticais do conteúdo orgânico de 50 amostras derivadas do furo de sondagem 9-FBA-61-BA, que permitiu conhecer melhor os representantes palinofaciológicos e palinológicos do Cretáceo Inferior da Bacia do Recôncavo, na área estudada. Através da observação a luz da microscopia óptica em luz branca transmitida e luz ultravioleta, foi possível posicionar temporalmente a seção, e individualizar quatro tipos de palinofácies distintas, levando-se em conta os tipos e o grau de preservação da matéria orgânica. As análises quantitativas do conteúdo orgânico mostram um predomínio de material orgânico de origem alóctone, representado por grãos de pólen, esporos e fitoclastos na base e no topo da seção, sendo sua porção média dominada por material orgânico amorfo autóctone. As mais altas fluorescências são observadas nas porções média e basal da seção indicando um ambiente mais redutor à época de sedimentação, destes estratos. Os dados de ICE apresentam valores de maturação entre 4,5 e 5,0 caracterizando um material orgânico maturo para geração de hidrocarbonetos. A associação palinoflorística identificada, bem como os dados litológicos obtidos, indicam um paleoambiente exclusivamente continental, composto por um sistema fluvial e deltaico-lacustre, sob um clima quente árido para a época deposicional. Tal associação enquadra-se àquelas observadas nas bacias do nordeste brasileiro e insere-se nas características das associações pertencentes à Província Microflorística Dicheiropollis (ex-WASA). Foram identificadas 57 espécies de palinomorfos, incluindo grãos de pólen, esporos, algas e fungos. A detecção das espécies, Dicheiropollis etruscus e Aequitriradites spinulosus, nos permitiu posicionar o intervalo nas biozonas Vitreisporites pallidus e Dicheiropollis etruscus, consideradas como de idades Hauteriviano Barremiano. / The present study was based on vertical variations analysis of the organic matter from 50 core samples collected from the well 9-FBA-61-BA, allowing better understanding of the Early Cretaceous of Reconcavo Basin palynological and palynofacies characteristics. Observations throughout combined light and blue light/UV fluorescence techniques, permitted to defined the section depositional time, and to distinguish four individual types of palynofacies, taking into account the variety and degree of preservation of organic matter.. Quantitative analysis of the organic content shows a predominance of allochthonous organic matter, represented by pollen, spores and phytoclasts on the base and top of the section; however the middle part is dominated by amorphous organic matter. On the other hand, the highest fluorescence was observed at the base and middle portion of the section suggesting a low oxidizing level at this sedimentation time. ICE data presents mature values ranging between 4.5 to 5.0 indicating that the deposits are in the oil generation window. The identified palynoflora and obtained lithological data suggests an exclusively continental paleoenvironment, composed by fluvial and deltaic - lake systems, in a warm and arid climate at the deposition time. Were identified 57 species of palynomorphs, including pollen, spores, algae and fungi. The detection of the Dicheiropollis etruscus and Aequitriradites spinulosus index species indicates these deposits belong to the Hauterivian - Barremian Vitreisporites pallidus and Dicheiropollis etruscus palynozones, respectively. This assemblage fits into those observed in the Brazilian northeastern basins and have the microfloristic assemblage characteristics that fit in to the Dicheiropollis Province (= WASA Province).

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O presente estudo baseou-se na análise das variações verticais do conteúdo orgânico de 50 amostras derivadas do furo de sondagem 9-FBA-61-BA, que permitiu conhecer melhor os representantes palinofaciológicos e palinológicos do Cretáceo Inferior da Bacia do Recôncavo, na área estudada. Através da observação a luz da microscopia óptica em luz branca transmitida e luz ultravioleta, foi possível posicionar temporalmente a seção, e individualizar quatro tipos de palinofácies distintas, levando-se em conta os tipos e o grau de preservação da matéria orgânica. As análises quantitativas do conteúdo orgânico mostram um predomínio de material orgânico de origem alóctone, representado por grãos de pólen, esporos e fitoclastos na base e no topo da seção, sendo sua porção média dominada por material orgânico amorfo autóctone. As mais altas fluorescências são observadas nas porções média e basal da seção indicando um ambiente mais redutor à época de sedimentação, destes estratos. Os dados de ICE apresentam valores de maturação entre 4,5 e 5,0 caracterizando um material orgânico maturo para geração de hidrocarbonetos. A associação palinoflorística identificada, bem como os dados litológicos obtidos, indicam um paleoambiente exclusivamente continental, composto por um sistema fluvial e deltaico-lacustre, sob um clima quente árido para a época deposicional. Tal associação enquadra-se àquelas observadas nas bacias do nordeste brasileiro e insere-se nas características das associações pertencentes à Província Microflorística Dicheiropollis (ex-WASA). Foram identificadas 57 espécies de palinomorfos, incluindo grãos de pólen, esporos, algas e fungos. A detecção das espécies, Dicheiropollis etruscus e Aequitriradites spinulosus, nos permitiu posicionar o intervalo nas biozonas Vitreisporites pallidus e Dicheiropollis etruscus, consideradas como de idades Hauteriviano Barremiano. / The present study was based on vertical variations analysis of the organic matter from 50 core samples collected from the well 9-FBA-61-BA, allowing better understanding of the Early Cretaceous of Reconcavo Basin palynological and palynofacies characteristics. Observations throughout combined light and blue light/UV fluorescence techniques, permitted to defined the section depositional time, and to distinguish four individual types of palynofacies, taking into account the variety and degree of preservation of organic matter.. Quantitative analysis of the organic content shows a predominance of allochthonous organic matter, represented by pollen, spores and phytoclasts on the base and top of the section; however the middle part is dominated by amorphous organic matter. On the other hand, the highest fluorescence was observed at the base and middle portion of the section suggesting a low oxidizing level at this sedimentation time. ICE data presents mature values ranging between 4.5 to 5.0 indicating that the deposits are in the oil generation window. The identified palynoflora and obtained lithological data suggests an exclusively continental paleoenvironment, composed by fluvial and deltaic - lake systems, in a warm and arid climate at the deposition time. Were identified 57 species of palynomorphs, including pollen, spores, algae and fungi. The detection of the Dicheiropollis etruscus and Aequitriradites spinulosus index species indicates these deposits belong to the Hauterivian - Barremian Vitreisporites pallidus and Dicheiropollis etruscus palynozones, respectively. This assemblage fits into those observed in the Brazilian northeastern basins and have the microfloristic assemblage characteristics that fit in to the Dicheiropollis Province (= WASA Province).

The environmental processes and conditions controlling productivity and organic matter (OM) accumulation/preservation as well as bottom–water redox conditions in the lower black shale (LBS) and upper black shale (UBS) members of the Devonian-Mississippian (D–M) Bakken Formation were evaluated utilizing trace metal (TM) concentrations, degree of pyritization (DOPT), enrichment factors (EF) of TMs, bi–metal ratios (V/Cr, V/(V+Ni), Ni/Co, U/Th), total sulfur (ST) vs. iron (Fe), total organic carbon (TOC), carbon–sulfur–iron relationships (C–S–Fe), as well as Mo–TOC and Mo EF–U EF relationships. High-resolution (1- to 3-cm scale) chemostratigraphic records were generated for twelve drill cores, four of which closely flank the N–S-trending axis of the Nesson Anticline, proximal to the center of the Williston Basin in northwest North Dakota, USA. Furthermore, five of the twelve drill cores were selected (sample selection was based on down–core spacing and TM concentrations) for petrographic and Rock-Eval analysis to assess variations in kerogen type, quantity, quality, and thermal maturity (based on solid bitumen reflectance (%SBRo), vitrinite reflectance equivalence (%VRE), Rock–Eval Tmax–derived vitrinite reflectance (%Ro)) from immature to condensate, wet gas hydrocarbon generation windows. Degree of pyritization (DOPT) values (0.25 to 1.0) indicate that bottom waters were frequently dysoxic (> 60%) with intermittent aerobic and anoxic/euxinic conditions which is in agreement with C–S–Fe and total ST vs. Fe assessments of paleoredox conditions and sedimentological evidence. Furthermore, using published Mo–TOC relationships from modern anoxic-euxinic basins, it is estimated that renewal time of the sub-chemoclinal water mass during accumulation of the LBS and UBS approximated 10 and 30 yrs., respectively. Agreement is also seen between Mo/TOC and Mo EF/U EF where both suggest the Bakken shales were deposited under relatively unrestricted water mass conditions resulting in consistent renewal of TMs into the basin. However, bi–metal ratios suggest > 80% of samples were deposited under suboxic to anoxic/euxinic conditions. Trace metal concentrations for the Bakken Fm. show considerable range for Co (0–10324 ppm), Mo (0–2018 ppm), Ni (0–1574 ppm), U (0–1604 ppm), and V (0–3194 ppm), and bi–metal ratios for the Bakken Fm. are up to 5x greater than those reported for other D–M black shale formations. The Bakken black shales represent a unique sedimentary system where the EF of various TMs such as Cu (6.2–7.7), Mo (219.7–237.8), Ni (9.4–10.2), U (20.6–29.3), V (9.9–14.2), and Zn (10.4–12.2) as well as total organic carbon contents (LBS = 10.80 and UBS = 11.80 avg. wt.%) are considerably higher than other Devonian–Mississippian black shales. In this study, raw distributions of elemental concentrations combined with bivariate and principal component analysis (PCA) were used to elucidate the processes that could have contributed to the high EF of TMs in the Bakken shales. Total organic carbon shares heavier PCA component loadings (>0.445) and stronger correlation coefficients (r) with Cu, Mo, Ni, U, V, and Zn rather than with pyrite-associated (As, Co, Fe, and S) elements, suggesting that TOC played a primary role in the scavenging and accumulation of TMs in the sediments. Reducing conditions within bottom waters or sediment pore waters may have accelerated the accumulation of redox-sensitive Cu, Mo, Ni, V, and Zn introduced into the sediments via primarily an organic matter (OM) detritus host and most likely played a secondary role in the enrichment of TMs. The high EF of TMs observed in the Bakken shales may be the result of the frequent resupply of TMs into basin waters, enhanced primary productivity that is necessary in scavenging TMs from the water column, the presence of H2S within sediment pore or bottom waters, or possibly secondary processes associated with basin-wide fluid and hydrocarbon migration. Factors controlling TM accumulation during time of deposition (e.g., TM availability, bottom-water redox conditions, adsorption onto organic matter) and during diagenesis and catagenesis (e.g., alteration and break down of organic matter, movement of fluid hydrocarbons or other basinal fluids) likely contribute to the lack of agreement between redox proxies, and subsequently, the lack of applicability of bi–metal ratios (i.e., V/Cr, V/(V+Ni), Ni/Co, U/Th) in assessing bottom–water conditions for the Bakken shales. Solid bitumen (SB), a secondary organic matter formed as a residue after hydrocarbon generation (through either sufficient thermal maturation or microbial degradation) and expulsion, is primarily dispersed within the mineral matrix and increases in quantity with increasing thermal maturity. Rock-Eval II and HAWK analyzers were used to measure and estimate the hydrogen index (HI; avg. 201 mg HC/g TOC), oxygen index (OI; avg. 7mg CO2/g TOC), S1 (free hydrocarbons; avg. 8.0 mg HC/g rock), S2 (hydrocarbons generated after cracking kerogen; avg. 24.3 mg HC/g rock), and %Ro (0.60–1.03%; estimated from Tmax). The HI and OI values are calculated from TOC as well as S2 and S3 (oxygen bonded to hydrocarbons). Plots of HI vs. Tmax (ºC) and HI vs. OI as well as S2 vs. S3 ratio were utilized to determine the type of kerogen, primary OM that is insoluble in organic solvents. However, these relationships are not in agreement with kerogen typing based on petrographic observations, where samples from more thermally mature cores plot as Type III (vitrinite) kerogen instead of observed Type I/II (marine algae) kerogen. This is largely due to the abundant presence of SB in the more thermally mature section of the Bakken (Rock-Eval Ro = 0.83–1.03%) as SB is known to have a lower HI content than Type II kerogen. Petrographic evidence shows greater abundance of alginite and amorphous organic matter (AOM or bituminite) in the thermally less mature (Rock-Eval Ro = 0.60–0.83%) section of the Bakken compared to the greater abundance of dispersed SB in the more thermally mature section where AOM is absent. Early research on the Bakken Fm. reported lower than expected vitrinite reflectance values attributed to vitrinite “suppression". The overall lack of vitrinite and abundance of solid bitumen in these shales suggests that these early attempts likely reported solid bitumen reflectance rather than vitrinite reflectance. More recent attempts to assess the thermal maturity of the Bakken Fm. black shales have measured and converted SBRo to vitrinite reflectance equivalent (VRE). However, samples selected for SBRo by some previous workers have included heterogenous, granular as well as high reflecting SB samples, which introduce error in the measurements. As such, reported reflectance values are most likely lower than they would be if smooth, homogenous solid bitumen with no inclusions were measured. For this project, smooth and homogenous SB was measured to produce consistent and reliable VRE values to assess the thermal maturity gradient from the Bakken Fm. basin margins to the depocenter. Blue-light fluorescence petrography was done to support thermal maturity assessments. Results from SBRo, Rock-Eval Ro, VRE, and blue-light fluorescence observations suggest that cores from the current study range from early oil window into condensate, wet gas.

Pela primeira vez incêndios florestais são identificados em uma associação de fácies contendo a Flora Dicroidium nos sedimentos avermelhados do Triássico Médio (Ladiniano) na parte sul da Bacia do Paraná (Formação Santa Maria, Rio Grande do Sul). A extensão geográfica dessa assembleia de plantas foi, assim, estendida no Gondwana brasileiro. As análises por petrografia orgânica, fluorescência, microscopia eletrônica de varredura (MEV) e microscopia eletrônica de varredura (tipo field emission gun - MEV-FEG) revelaram a presença recorrente de carvão vegetal (charcoal) na sucessão vertical de fácies relacionadas a um modelo deposicional de fluxos efêmeros de baixa densidade do tipo inunditos. O carvão microscópico (micro-charcoal) ocorre como fragmentos comuns em diferentes fácies, enquanto que o carvão vegetal macroscópico (macro-charcoal) é representado por espécimes tridimensionais de lenhos atribuídos a gimnospermas (Pinaceae?) e por fragmentos achatados, finos e alongados atribuídos a pteridospermas (rachises de Dicroidium?) Os valores médios de reflectância da inertinita entre 2,80-6,61 %Ro medidos nos fragmentos de macro-charcoal evidenciaram processos de queima de alta temperatura, envolvendo tanto incêndios na copa quanto na interface copa-superfície. A recorrência de fragmentos queimados em várias fácies do perfil estudado indica a ocorrência de incêndios regionais que afetaram tanto as comunidades meso-xerófilas distais quanto às associações proximais higro- mesófilas, compostas majoritariamente por espécimes da Flora Dicroidium. A integração dos resultados obtidos a partir das múltiplas análises dos fragmentos de charcoal é consistente com um teor de oxigênio atmosférico superior a 20%. / For the first time wildfires are reported from an association of different facies containing a Dicroidium flora from the Middle Triassic (Ladinian) red beds in the southern part of the Paraná Basin (Santa Maria Formation, Rio Grande do Sul state). The geographical extension of the Dicroidium plant assemblage has thus been extended in the Brazilian Gondwana. Analyses through petrography, fluorescence microscopy, scanning (SEM) and field emission gun scanning electron microscopy (FEG-SEM) revealed recurrent charcoal presence in a vertical facies succession of depositional cycles related to ephemeral prograding low density flows. Microscopic charcoal occurs as common fragments within different facies whereas macroscopic charcoal is represented by tridimensional wood specimens assigned to gymnosperms (Pinaceae?) and by flattened, thin, elongated remains assigned to pteridospermophytes (rachises of Dicroidium?). Average reflectance values between 2.80-6.61 %Ro measured in the macro-charcoals evidenced burning processes of high temperature, involving fires both in the crown and in the crown-surface interface. The recurrence of charcoal in several facies of the studied profile indicates regional wildfires, which affected hinterland, meso-xerophyllous coniferous assemblages and marginal hygro-mesophyllous Dicroidium-like assemblages. The integration of results obtained from the multiple charcoal analyses is consistent with atmospheric oxygen content higher than 20%.

Pela primeira vez incêndios florestais são identificados em uma associação de fácies contendo a Flora Dicroidium nos sedimentos avermelhados do Triássico Médio (Ladiniano) na parte sul da Bacia do Paraná (Formação Santa Maria, Rio Grande do Sul). A extensão geográfica dessa assembleia de plantas foi, assim, estendida no Gondwana brasileiro. As análises por petrografia orgânica, fluorescência, microscopia eletrônica de varredura (MEV) e microscopia eletrônica de varredura (tipo field emission gun - MEV-FEG) revelaram a presença recorrente de carvão vegetal (charcoal) na sucessão vertical de fácies relacionadas a um modelo deposicional de fluxos efêmeros de baixa densidade do tipo inunditos. O carvão microscópico (micro-charcoal) ocorre como fragmentos comuns em diferentes fácies, enquanto que o carvão vegetal macroscópico (macro-charcoal) é representado por espécimes tridimensionais de lenhos atribuídos a gimnospermas (Pinaceae?) e por fragmentos achatados, finos e alongados atribuídos a pteridospermas (rachises de Dicroidium?) Os valores médios de reflectância da inertinita entre 2,80-6,61 %Ro medidos nos fragmentos de macro-charcoal evidenciaram processos de queima de alta temperatura, envolvendo tanto incêndios na copa quanto na interface copa-superfície. A recorrência de fragmentos queimados em várias fácies do perfil estudado indica a ocorrência de incêndios regionais que afetaram tanto as comunidades meso-xerófilas distais quanto às associações proximais higro- mesófilas, compostas majoritariamente por espécimes da Flora Dicroidium. A integração dos resultados obtidos a partir das múltiplas análises dos fragmentos de charcoal é consistente com um teor de oxigênio atmosférico superior a 20%. / For the first time wildfires are reported from an association of different facies containing a Dicroidium flora from the Middle Triassic (Ladinian) red beds in the southern part of the Paraná Basin (Santa Maria Formation, Rio Grande do Sul state). The geographical extension of the Dicroidium plant assemblage has thus been extended in the Brazilian Gondwana. Analyses through petrography, fluorescence microscopy, scanning (SEM) and field emission gun scanning electron microscopy (FEG-SEM) revealed recurrent charcoal presence in a vertical facies succession of depositional cycles related to ephemeral prograding low density flows. Microscopic charcoal occurs as common fragments within different facies whereas macroscopic charcoal is represented by tridimensional wood specimens assigned to gymnosperms (Pinaceae?) and by flattened, thin, elongated remains assigned to pteridospermophytes (rachises of Dicroidium?). Average reflectance values between 2.80-6.61 %Ro measured in the macro-charcoals evidenced burning processes of high temperature, involving fires both in the crown and in the crown-surface interface. The recurrence of charcoal in several facies of the studied profile indicates regional wildfires, which affected hinterland, meso-xerophyllous coniferous assemblages and marginal hygro-mesophyllous Dicroidium-like assemblages. The integration of results obtained from the multiple charcoal analyses is consistent with atmospheric oxygen content higher than 20%.

Pela primeira vez incêndios florestais são identificados em uma associação de fácies contendo a Flora Dicroidium nos sedimentos avermelhados do Triássico Médio (Ladiniano) na parte sul da Bacia do Paraná (Formação Santa Maria, Rio Grande do Sul). A extensão geográfica dessa assembleia de plantas foi, assim, estendida no Gondwana brasileiro. As análises por petrografia orgânica, fluorescência, microscopia eletrônica de varredura (MEV) e microscopia eletrônica de varredura (tipo field emission gun - MEV-FEG) revelaram a presença recorrente de carvão vegetal (charcoal) na sucessão vertical de fácies relacionadas a um modelo deposicional de fluxos efêmeros de baixa densidade do tipo inunditos. O carvão microscópico (micro-charcoal) ocorre como fragmentos comuns em diferentes fácies, enquanto que o carvão vegetal macroscópico (macro-charcoal) é representado por espécimes tridimensionais de lenhos atribuídos a gimnospermas (Pinaceae?) e por fragmentos achatados, finos e alongados atribuídos a pteridospermas (rachises de Dicroidium?) Os valores médios de reflectância da inertinita entre 2,80-6,61 %Ro medidos nos fragmentos de macro-charcoal evidenciaram processos de queima de alta temperatura, envolvendo tanto incêndios na copa quanto na interface copa-superfície. A recorrência de fragmentos queimados em várias fácies do perfil estudado indica a ocorrência de incêndios regionais que afetaram tanto as comunidades meso-xerófilas distais quanto às associações proximais higro- mesófilas, compostas majoritariamente por espécimes da Flora Dicroidium. A integração dos resultados obtidos a partir das múltiplas análises dos fragmentos de charcoal é consistente com um teor de oxigênio atmosférico superior a 20%. / For the first time wildfires are reported from an association of different facies containing a Dicroidium flora from the Middle Triassic (Ladinian) red beds in the southern part of the Paraná Basin (Santa Maria Formation, Rio Grande do Sul state). The geographical extension of the Dicroidium plant assemblage has thus been extended in the Brazilian Gondwana. Analyses through petrography, fluorescence microscopy, scanning (SEM) and field emission gun scanning electron microscopy (FEG-SEM) revealed recurrent charcoal presence in a vertical facies succession of depositional cycles related to ephemeral prograding low density flows. Microscopic charcoal occurs as common fragments within different facies whereas macroscopic charcoal is represented by tridimensional wood specimens assigned to gymnosperms (Pinaceae?) and by flattened, thin, elongated remains assigned to pteridospermophytes (rachises of Dicroidium?). Average reflectance values between 2.80-6.61 %Ro measured in the macro-charcoals evidenced burning processes of high temperature, involving fires both in the crown and in the crown-surface interface. The recurrence of charcoal in several facies of the studied profile indicates regional wildfires, which affected hinterland, meso-xerophyllous coniferous assemblages and marginal hygro-mesophyllous Dicroidium-like assemblages. The integration of results obtained from the multiple charcoal analyses is consistent with atmospheric oxygen content higher than 20%.