Facies and stratigraphic architecture right at the transition from marine to non-marine environments is poorly documented. In the Cretaceous outcrops of Utah, Star Point and Blackhawk Formations are well studied. The nature of spatio-temporal transition of these two Formations, in the deposition-strike orientation, remains undocumented. This study characterizes facies and stratigraphic complexity at the transition of the two Formations that crop out in depositional-strike orientation in the Wasatch Plateau. Data from outcrop including photomosiacs and measured sections demonstrate this complexity at a range of scales. The Star Point constitutes a shoreface environment. The Blackhawk constitutes a coastal-fluvial environment. In the northern part of study area, the transition from marine to continental strata is expressed by intertonguing succession. The dip-oriented outcrops show pinch-outs of two parasequences into coastal-plain deposits. This complexity decreases southward, the southern outcrops show a simple transition. At least two sequence boundaries are correlated across the outcrop belt.

A Formação Piauí registra a deposição de um sistema eólico, fluvial e marinho raso acumulado em uma bacia de sinéclise intracratônica. A caracterização das associações de fácies e do arcabouço estratigráfico foi feito através de uma descrição detalhada das fácies sedimentares e levantamento de perfis de afloramentos. As fácies foram classificadas de acordo com a textura dos grãos (tamanho e seleção) e estruturas sedimentares observadas. Medidas de paleocorrentes foram feitas nas estratificações e laminações cruzadas. Os perfis foram medidos na escala 1:50 em locais com boa exposição vertical. Seis associações de fácies foram reconhecidas, dunas e interdunas eólicas, lençóis de areia eólicos, canais fluviais, canais fluviais influenciados por maré, shoreface superior e shoreface inferior. Através da correlação das superfícies estratigráficas as associações de fácies foram organizadas em tratos de sistema, que formaram oito sequências deposicionais de alta frequência, delimitados por discordâncias subaéreas. Estas sequências são compostas por um trato de sistemas de nível baixo (TSNB), que é dominado por sistemas eólicos ou fluviais, um trato de sistemas transgressivo (TST), que é formado por canais fluviais influenciados por maré e/ou depósitos de shoreface superior e inferior com empilhamento retrogradacional, e um trato de sistemas de nível alto (TSNA), que é formado por depósitos de shoreface superior e inferior com empilhamento progradacional. Duas sequências deposicionais de mais baixa frequência foram determinadas ao observar o empilhamento das sequências de alta frequência. Ambas as sequências são formadas por uma regressão inicial seguida por uma transgressão progressiva. O principal controle das variações no nível relativo do mar durante a acumulação da Formação Piauí foi glacio-eustático. Contudo, mudanças climáticas estavam associadas com as fases glacio-eustáticas e influenciaram a deposição eólica e fluvial. / The Piauí Formation records the deposition of aeolian, fluvial and shallow marine systems accumulated in a cratonic sag basin. Characterization of the facies associations and sequence stratigraphic framework was done by detailed description of sedimentary facies and logging of outcrops. The facies were classified based on grain texture (size and selection) and sedimentary structures observed. Paleocurrent orientations were measured from cross-strata. Stratigraphic sections were measured at a 1:50 scale at outcrops with good vertical exposure. Six facies associations were recognized: aeolian dunes and interdunes, aeolian sandsheets, fluvial channels, tidally-influenced fluvial channels, upper shoreface and lower shoreface. Through correlation of stratigraphic surfaces the facies associations were organized in system tracts, which formed eight high frequency depositional sequences, bounded by subaerial unconformities. These sequences are composed of a lowstand system tract (LST), that is aeolian-dominated or fluvial-dominated, a transgressive system tract (TST) that is formed by tidally-influenced fluvial channels and/or upper and lower shoreface deposits with retrogradational stacking, and a highstand system tract (HST), which is formed by lower and upper shoreface deposits with progradational stacking. Two low frequency cycles were determined by observing the stacking of the high frequency cycles. Both sequences are formed by an initial regression followed by a progressive transgression. The main control on sedimentation in Piauí Formation was glacioeustasy, which was responsible for the changes in relative sea level. Even though, climate changes were associated with glacioeustatic phases and influenced the aeolian and fluvial deposition.

O termo Coal Bed Methane (CBM) refere-se ao metano gerado nas camadas de carvão e é um alvo exploratório na indústria do petróleo. Desde os anos setenta quando o CBM foi visto como uma fonte de energia economicamente viável estudos foram direcionados no entendimento de sua ocorrência, distribuição, viabilidade, produtividade e recuperação (Flores, 1997). Atualmente o CBM é produzido economicamente e investigado em diversas bacias carboníferas do mundo. No Brasil as principais acumulações de carvão são de idade Permiana e fazem parte da Formação Rio Bonito da Bacia do Paraná. De várias jazidas de carvão conhecidas a Jazida de Santa Terezinha, nordeste do estado do Rio Grande do Sul, é a que certamente apresenta o maior potencial para CBM. Seu condicionamento como um baixo estrutural com camadas de carvão de espessuras significativas ocorrendo entre 400m e 1000m de profundidade conferiram a jazida uma situação favorável para geração de metano. Uma boa quantidade de dados geológicos provenientes de diversos poços testemunhados foi utilizada para caracterização estratigráfica do intervalo carbonoso da jazida. A descrição detalhada de testemunhos deu embasamento para análise de fácies e sistemas deposicionais permitindo o reconhecimento de parasseqüências, cujo empilhamento evidenciou uma seqüência deposicional dominantemente transgressiva apresentando na base depósitos aluviais, na porção intermediária sistemas lagunares/paludais com formação de turfeiras, e no topo depósitos marinhos. A análise estrutural revelou uma forte compartimentação tectônica das camadas de carvão, deslocadas por falhamentos normais de alto rejeito. A integração de dados estratigráficos com a determinação do padrão de estruturação atual e demais complexidades forneceu elementos para o reconhecimento de uma zona com melhores condições para exploração de CBM na Jazida de Santa Terezinha. / Coal bed methane (CBM0 refers to the methane gas generated in coal beds and is a worldwide target in the petroleum industry. Since the Seventies when CBM was seen like a economically viable energy source studies had been directed to understand it’s occurrence pattern, distribution, viability, productivity and recovery (Flores, 1997). Nowadays CBM is economically produced and investigated in several coaly basins around the world (USA, China). In Brazil the main coal accumulations are of Permian age being part of the Rio Bonito Formation of Parana Basin. From all known coalfields the Santa Terezinha coalfield, in the northeastern region of Rio Grande do Sul state, certainly is the one that presents greater potential to CBM. The structural conditioning and the good thickness of coal beds occurring in depths between 400m and 1000m emplaced the coalfield in a favorable situation to methane generation. Tens of cored wells were utilized to the stratigraphic characterization of the coal bearing interval. A detailed description of cores supplied informations to facies and depositional environments analysis allowing the recognition of parasequences with a dominant retrogradational pattern characterizing a manly transgressive depositional sequence showing aluvial deposits at the base, marsh and lacustrine deposits in middle portion and marine strata on top. The structural analysis revealed a strong tectonic compartmentation of coal beds, displaced by normal faults with high slip. The integration of stratigraphic data with the determination of actual structural patterns and other complexities allowed the recognition of a zone with better conditions to CBM exploration in the Santa Terezinha coalfield.

Na costa do leste do Brasil, destacam-se importantes acumulações de carbonatos lacustres do Cretáceo (Aptiano) relacionadas à fase de rift que precede a abertura do Oceano Atlântico, estes carbonatos consistem principalmente em espessos pacotes de bivalves associados a sedimentos siliciclásticos finos. Na bacia de Campos este intervalo equivale a Formação Coqueiros e é portador de hidrocarbonetos sendo reservatório nos campos de Badejo, Linguado, Pampo e Trilha. Estes reservatórios são o foco deste estudo, que teve como objetivo aprofundar o conhecimento desses depósitos através da análise das fácies e associações de fácies para definição de sequências seguindo a compreensão atual dos conceitos de estratigrafia de sequência. Foram descritos testemunhos de poços associados a análise de dados de perfil e sísmica através das quais foram definidas dezesseis fácies. A classificação das fácies utilizou critérios sedimentológicos associados a conceitos tafonômicos o que permitiu a intepretação dos processos sedimentares envolvidos em sua deposição Estas fácies foram agrupadas em associações de acordo com gradiente hidrodinâmico de uma plataforma dominada por ondas o que permitiu a interpretação dos padrões de empilhamento e definição de tratos de sistema transgressivos e regressivos. Foi proposto um ciclo ideal de alta frequência com a sucessão esperada de fácies para cada trato que serviu de base para interpretação de sequências de alta e média frequência. Esta análise permitiu a definição de três sequências internas no intervalo conhecido como Coquina Inferior, correlacionadas entre os poços que possuíam a melhor amostragem do intervalo permitindo assim analisar a variação vertical e lateral de fácies. A metodologia proposta permite a intepretação da estratigrafia em uma escala de maior detalhe auxiliando a interpretação da ocorrência de fácies e sua distribuição espacial na escala de dezenas a centenas de metros. Este tipo de análise é importante para desenvolvimento da produção de campos de hidrocarbonetos sendo útil na construção de modelos geológicos. Pode ser aplicável a ambientes análogos com similaridades quanto à composição das rochas e os processos envolvidos em sua deposição, como a Formação Itapema análoga na Bacia de Santos. / On the eastern Brazilian coast there is an important accumulation of Cretaceous lacustrine carbonates linked to the rift phase, which precedes the opening of the Atlantic Ocean. These carbonates consist mainly of bivalve packages associated with fine siliciclastic sediments. In the Campos Basin this interval is denominated Coqueiros Formation and constitutes a hydrocarbon reservoir in the fields of Badejo, Linguado, Pampo and Trilha. These reservoirs are the focus of this study, which aimed to detail the knowledge of these deposits through the analysis of facies and their associations in order to define sequences according to the present understanding of sequence stratigraphy concepts. Core samples description, well logs and seismic data analyses have been carried out, allowing the definition of sixteen facies. The facies classification was based on sedimentary characteristics associated with taphonomic concepts that allowed the interpretation of sedimentary processes involved in the deposition. These facies were grouped in associations according to a hydrodynamic gradient of a wave-dominated platform, which allowed the interpretation of stacking patterns and the definition of both transgressive and regressive system tracts It was proposed an ideal high frequency cycle with the facies succession from each tract which was used for the interpretation of high and medium frequency sequences. This analysis allowed the definition of three internal sequences in the so-called Lower Coquina Interval correlated among the best sampled wells, and the analysis of vertical and lateral variation of facies. The proposed methodology allows the interpretation of the stratigraphy in a small scale contributing to the interpretation of the occurrence of facies and their spatial distribution in a scale of tens to hundreds of meters. This type of analysis is important for the development of production in a hydrocarbon field and is useful for the construction of geological models and is applicable to similar environments with same composition of the rocks and similarities in the processes involved in their deposition, such as the Itapema Formation in the Santos Basin.

As camadas de carvão de idade Permiana da Formação Rio Bonito de Candiota constituem o maior depósito do país. Atualmente são mineradas duas camadas, denominadas “Camada Candiota Superior” e “Camada Candiota Inferior”. As outras camadas, S1-S9 (camadas superiores) e I1-I5 (camadas inferiores), não são explotadas. O objetivo deste trabalho foi realizar um detalhamento das camadas inferiores, superiores e Banco Louco do depósito, utilizando como metodologia a aplicação dos conceitos de sedimentologia e estratigrafia de sequências; petrologia do carvão (descrição dos litotipos, análise da reflectância da vitrinita e análise de macerais) e análises químicas (imediatas, elementares, poder calorífico e difração de raios X). Foram identificados quatro sistemas deposicionais na área: leque aluvial, fluvial, laguna-barreira e marinho raso. A partir da base, a sucessão de litofácies compreende conglomerados matriz-suportado e arenitos grossos, sugerindo um ambiente típico para sistemas de leques aluviais e fluviais, com camadas de carvão pouco desenvolvidas (camadas inferiores). As principais camadas de carvão (espessas e contínuas) ocorrem no subambiente lagunar, no final do Trato de Sistemas Transgressivo da seqüência 2. As camadas superiores desenvolvem-se no Trato de Sistemas de Nível Alto e Trato de Sistemas de Nível Baixo, sendo tipicamente finas e descontinuas. Em seguida ocorrem sedimentos marinhos no topo da seção (Formação Palermo), sobrepostos à sucessão portadora de carvão. Os resultados das reflectâncias da vitrinita das camadas analisadas indicam um rank de carvão sub-bituminoso C (Rrandom= 0,36% - 0,47%), com evidências de alguns valores anômalos baixos relacionados ao alto conteúdo de matéria mineral. A análise dos litotipos determinou o litotipo fosco (durênio) predominante. A composição dos macerais é altamente variável, com algumas camadas extremamente ricas em macerais do grupo da inertinita (fusinita, semifusinita, inertodetrinita). A petrologia juntamente com a estratigrafia de seqüências mostra que as características do carvão são controladas pelo ambiente deposicional. Os resultados da análise elementar apresentam teores médios em peso das amostras de 28,3% para o carbono, 2,8% para o hidrogênio, 0,6% para o nitrogênio, 1,9% para o enxofre total e 20,3% para o oxigênio. A matéria volátil apresenta em média 43,6% em peso (d.a.f.) classificando as camadas de carvão como sub-bituminoso A. O poder calorífico calculado em uma base seca e livre de cinzas (d.a.f.) obteve valor médio de 5588 cal/g, classificando as amostras como sub-bituminoso B. Através da difração de raios X a mineralogia é constituída principalmente por quartzo, caolinita e ilita. As camadas de carvão analisadas são ricas em cinzas, utilizando os critérios do International Classification of in-Seam Coals (1998), a maioria das camadas é classificada como carvões de categoria muito inferior, entretanto, as camadas S4, I1, I4 e I5 são classificadas como rochas carbonosas (>50% em peso de cinza). Conforme dados da CRM, a usina termelétrica Presidente Médici pode operar com até 53% % em peso de cinzas e 2,0 de enxofre total. Assim sendo, as camadas S3, S6, S7, S8, S9, BL, I3 e I4 atenderiam as exigências de teor de cinzas e enxofre total máximo e exigido pela termelétrica. / The Candiota Coalfield, RS, is the largest coal deposit in the country, with coal seams developed in the Permian age the Rio Bonito Formation. Currently two seams are mined, called "Seam Candiota Superior" and "Seam Candiota Inferior". The other seams, S1-S9 (upper seams) and I1-I5 (lower seams) have not being mined so far. The aim of the present study was a characterization of the lower and upper seams of the deposit using methods of sequence stratigraphy and sedimentology, coal petrology (coal lithotypes, vitrinite reflectance, maceral analyses), and chemical characterization (proximate analysis, ultimate analysis, calorific value determination and x-ray diffraction). Sedimentological analyses identified four depositional systems in the area: alluvial fan, fluvial, lagoon-barrier and shallow marine. From the base, the succession of lithofacies comprises matrix-supported conglomerates and coarse grained sandstones, suggesting a typical environment for systems dominated by alluvial fans and river, with poorly developed coal seams (lower seams). The main coal seams (continuous, thick) occur in a lagoon-type subenvironment at the final stage of a transgressive systems tract of sequence 2. The upper seams developed in a Highstand Systems Tract and Lowstand Systems Tract, and are typically thin and discontinuous. Marine sediments occur at the top of the section (Palermo Formation), overlapping the coal-bearing strata. The results of the vitrinite reflectance measurements of the coal seams indicate a rank of sub-bituminous C (Rrandom = 0.36 - 0.47%), with evidence of some anomalous low values related to the high content of mineral matter. The dominant lithotype in the coal seams is durain. The maceral composition is highly variable, with some seams extremely rich in the maceral group inertinita (fusinite, semifusinite, inertodetrinite). The petrology along with the sequence stratigraphic interpretation show that the characteristics of the coal seams are controlled by depositional environment. Results from elemental analysis show that the average content (wt.%) were: 28.3% carbon, 2.8 % hydrogen, 0.6% for nitrogen, 1.9% for total sulfur and 20.3% for oxygen. The average volatile matter content obtained from proximate analyses is 43.6 wt% (daf), classifying the seams as sub-bituminous A. The average calorific value calculated on an dry, ash-free basis (daf) is 5588 cal /g, classifying the samples as sub-bituminous B. Based on results from x-ray diffraction the mineralogy consists mainly of quartz, kaolinite and illite. The coal seams are rich in ashes, ranging from 32,0 to 62,3 wt%, with most seams according to the International Classification System ranked as very low quality coals. Seams such as S4, I1, I4 and I5 are classified as carbonaceous rocks (> 50 wt.% ash). According to data from CRM, the President Medici power plant in Candiota can operate with coal containing of up to 53% wt% ash and 2,0 wt% total sulfur. Thus, coal seams S3, S6, S7, S8, S9, BL, I3 and I4 meet the requirements of maximum ash and total sulphur contents for combustion in the power plant.

The Middle Ordovician Ancell Group, including the St. Peter Sandstone, Glenwood Shale and Starved Rock Formation, records intracontinental basin development during eustatic sea level changes in Iowa and Illinois. The St. Peter Sandstone overlies the Prairie du Chien Group across an erosional unconformity that marks a major sequence boundary, whereas upper contact of the St. Peter Sandstone with the Glenwood Shale also is a second sequence boundary. Data from 80 wells, selected well logs, and 20 cores were integrated to refine the high-resolution sequence stratigraphy of the Ancell Group. Two main sequences bounded by three sequence boundaries are interpreted to represent 3rd order sequences. Distinctive shallowing-upward parasequences bounded by flooding surfaces in many cores record higher frequency relative sea level fluctuations in the Ancell Group, but these cannot presently be correlated regionally. Facies variations define an aggradational transgressive systems tract TST), a prograding highstand systems tract (HST) and down stepping falling stage system tract (FSST) in both the St. Peter Sandstone and the Glenwood Shale-Starved Rock Formation units. The St. Peter Sandstone thickens towards the northeast and thins to the northwest and southwest in Iowa. In contrast, the St. Peter Sandstone in Illinois thickens to the south likely recording a prolonged FSST incised valley or channel fill. Detrital zircon geochronology of 13 samples from the St. Peter Sandstone and Starved Rock Formation define common peaks at 1100-1500 Ma and 2500-2700 Ma with minor components at 1670-1750 Ma and 3000-3600 Ma. The detrital zircon signature is dominated by Archean, and Grenville (1000-1300 Ma) ages. The detrital zircon geochronology indicates that the Ancell Group was sourced directly from the Archean Superior Province to the north and Grenville Province to the northeast, although recycling of Archean grains from the Paleoproterozoic Huron Basin cannot be ruled out. The near complete lack of 1800-1900 Ma ages argues against derivation of detritus from the Trans-Hudson or Penokean Orogens. The Transcontinental Arch northwest of the Iowa Basin acted as a barrier to sediment transport from the Trans-Hudson Orogen. Basement rocks of the Penokean Orogen are inferred to have been covered by water or younger sediments southeast of the Iowa Basin. CIA analyses of Ordovician shale samples from around the Transcontinental Arch indicate that the climate condition during Middle Ordovician time was warm and humid. This is consistent with a paleoclimate interpretation where mechanical erosion and chemical weathering yielded first cycle mature quartz arenites (Witzke, 1980).

The Lower to Middle Ordovician Garden City Formation and Pogonip Group are coeval successions of mixed carbonate and siliciclastic rocks deposited under normal marine conditions on a shallow carbonate ramp on the western margin of Laurentia. The Garden City Formation was deposited in the Northern Utah Basin and the Pogonip Group was deposited in the Ibex Basin. These two basins experienced different rates of thermal subsidence following Neoproterozoic rifting along the western margin of Laurentia resulting in significant thickness differences between rock units and varying lithologic expressions of eustatic change. This study provides a unique opportunity to examine the lithologic, geochemical, and paleontological responses to eustatic oscillations of two coeval sedimentary basins in Utah that formed under different tectonic settings and subsidence rates. The Garden City Formation is composed of fourteen lithotypes and the Pogonip Group is composed of eleven lithotypes. These lithotypes mainly represent depositional environments ranging from inner ramp and middle ramp with minor outer ramp deposits. Many lithologies appear to be storm influenced due to the presence of abundant rip-up clasts (intraclasts), fragmented bioclasts, and occasional mega-ripples. Other lithologies have been extensively bioturbated and burrowed. Nine stratigraphic sequences have previously been identified within the Pogonip Group. Eight equivalent, albeit compressed, sequences within the Garden City Formation were located using biostratigraphic and chemostratigraphic correlations, and increases in insoluble residues often found at the bases of sequence boundaries. Sequences are expressed as deepening-upward packages containing silty/sandy lowstand deposits that transition into wackestones and lime mudstone-rich highstand deposits. Several sequence boundaries appear to coincide with conodont and/or trilobite extinction events. Important sequence boundaries mark the Sauk III-m and Sauk IV-m transition and the Ibexian- Whiterockian Series boundary. Meter-scale cycles are common and likely related to Milankovitch cyclicity. Insoluble residue increases upsection at each location which may indicate a gradual overall drop in sea level due to the onset of the regressive upper portion of the Sauk III supersequence. Insoluble residue from the Pogonip Group ranges from 1.2 to 84.7 wt. % with an average of 16.0 wt. % ± 0.7 wt. %. Insoluble residue from the Garden City Formation ranges from 1.5 to 63.8 wt. % with an average of 13.4 wt. % ± 1.0 wt. %. New stable carbon isotope data (δ13C) from the Garden City Formation and the Pogonip Group range from -2.92 to 1.23 ‰ V-PDB and -2.19 to 0.56 ‰ V-PDB, respectively. Four distinct δ13C trends are recognized in both sections: 1) a drop in δ13C from positive values between 0.2-1.0 ‰ to negative values approaching -1.0 ‰ near the base of the Ordovician, 2) a 0.5 to 1.0 ‰ positive δ13C excursion near the top of the Rossodus manitouensis Zone, 3) a drop in δ13C values to near -2.0 ‰ through most of the Acodus deltatus –Oneotodus costatus Zone, and 4) a gradual increase in δ13C from - 2.0 ‰ to -1.0 ‰ throughout the remainder of the sections. δ13C of the Garden City Formation and the Pogonip Group appear to be correlative based on these distinct trends. This correlative relationship was verified by the lowest occurrence of conodont species Scolopodus filosus and Scalpellodus n. sp. A of the Low Diversity Interval which coincides with the positive δ13C excursion in both the Garden City Formation and the Pogonip Group. New δ13C data likely represent global primary seawater chemistry based on the correlation of similar δ13C trends from the Argentine Precordillera and western Newfoundland.

A sequence stratigraphic study was conducted on the Mendi and Darai Limestone Megasequences in the foreland area of the Papuan Basin in Papuan New Guinea. It involved the integrated use of seismic, wireline log, well core and cuttings, strontium isotope age and biostratigraphic data. This study enhanced the understanding of the structure, stratigraphy and depositional architecture of the limestones, and the morphology of the basin at the time of deposition. The results of the study were integrated with published geological and tectonic models for the Papuan Basin to develop a consistent and coherent model for the depositional history of the limestones. Eleven third-order sequences were delineated within the Mendi and Darai Limestone Megasequences. Eight depositional facies were interpreted across these sequences, namely deep-shelf, shallow-shelf, backreef, reef, shoal, forereef, basin margin and submarine fan facies. Each facies was differentiated according to seismic character and geometry, well core and cuttings descriptions, and its position in the depositional framework of the sequence. Deposition of the Mendi Limestone Megasequence commenced in the Eocene in response to thermal subsidence and eustatic sea-level rise. Sedimentation comprised open-marine, shallow-water, shelfal carbonates. During the middle of the Oligocene, the carbonate shelf was exposed and eroded in response to the collision of the Australian and Pacific Plates, or a major global eustatic sea-level fall. Sedimentation recommenced in the Late Oligocene, however, in response to renewed extensional faulting and subsidence associated with back-arc extension. This marked the onset of deposition of the Darai Limestone Megasequence in the study area. The KFZ, OFZ and Darai Fault were reactivated during this time, resulting in the oblique opening of the Omati Trough. Sedimentation was initially restricted to the Omati Trough and comprised deep and shallow-marine shelfal carbonates. By the Early Miocene, however, movement on the faults had ceased and an extensive carbonate platform had developed across the Gulf of Papua. Carbonate reef growth commenced along topographic highs associated with the KFZ, and led to the establishment of a rimmed carbonate shelf margin. Shallow to locally deeper-marine, shelfal carbonates were deposited on this shelf, and forereef, submarine fan and basin margin carbonates were deposited basinward of the shelf margin. The Uramu High and parts of the Pasca High became submerged during this time and provided sites for pinnacle reef development. During the middle of the Early Miocene, a major global eustatic sea-level fall or flexure of the Papuan Basin associated with Early Miocene ophiolite obduction subaerially exposed the carbonate shelf. This resulted in submarine erosion of the forereef and basin margin sediments. Towards the end of the Early Miocene, however, sedimentation recommenced. Shallow-marine, undifferentiated wackestones and packstones were deposited on the shelf; forereef, submarine fan and basin margin sediments were deposited basinward of the shelf margin; and reef growth recommenced along the shelf margin and on the Pasca and Uramu Highs. By the end of the Early Miocene, however, the pinnacle reef on the Pasca High had drowned. During the middle of the Middle Miocene, subtle inversion associated with ophiolite obduction subaerially exposed the carbonate shelf, and resulted in submarine erosion of the forereef and basin margin sediments. Sedimentation recommenced towards the end of the Middle Miocene, however, in response to eustatic sea-level rise and flexure of the crust associated with foreland basin development. Shallow marine, undifferentiated wackestones, packstones and grainstones were deposited on the shelf; carbonate shoals were deposited along the shelf margin; and forereef, submarine fan and basin margin carbonates were deposited basinward of the shelf margin. Carbonate production rapidly outpaced accommodation space on the shelf during this time, resulting in highstand shedding and the development of a large prograding submarine fan complex basinward of the shelf margin. By the Late Miocene, carbonate deposition had ceased across the majority of the study area in response to a major global eustatic sea-level fall or inversion associated with terrain accreation events along the northern Papuan margin. Minor carbonate deposition continued on parts of the Uramu High, however, until the middle of the Late Miocene. During the latest Miocene, clastic sediments prograded across the carbonate shelf, infilling parts of the foreland basin. Plio-Pleistocene compression resulted in inversion and erosion of the sedimentary package in the northwestern part of the study area. In the southeastern part of the Papuan Basin, however, clastic sedimentation continued to the present day.

<p>Development of a predictive model for the distribution of diagenetic alterations and related evolution of reservoir quality of sandstones was achieved by integrating the knowledge of diagenesis to sequence stratigraphy. This approach allows a better elucidation of the distribution of eogenetic alterations within sequence stratigraphy, because changes in the relative sea level induce changes to: (i) pore water chemistry, (ii) residence time of sediments under certain near-surface geochemical conditions, (iii) variations in the detrital composition, and (iv) amounts and type of organic matter.</p><p>This thesis revealed that eogenetic alterations, which are linked to sequence stratigraphy and have an impact on reservoir quality evolution, include formation of: (i) pseudomatrix and mechanically infiltrated clays in fluvial sandstones of the lowstand and highstand systems tracts (LST and HST, respectively), (ii) kaolinite in tide-dominated deltaic and foreshore-shoreface sandstones of HST, Gilbert-type deltaic sandstones of LST and fluvial deltaic sandstones of LST, (iii) kaolinite and mechanically infiltrated clays in sandstones lying below sequence boundary, (iv) K-feldspar overgrowths in fluvial deltaic LST, (v) glaucony towards the top of fluvial deltaic LST immediately below and at transgressive surface (TS) and in foreshore and shoreface transgressive systems tracts (TST) below parasequence boundaries (PB) and maximum flooding surface (MFS), (vi) framboidal pyrite and extensive cementation by calcite and dolomite in foreshore and shoreface and tide-dominated deltaic TST, and shoreface and tidal flat HST bioclastic-rich arenites particularly in the vicinity of PB, TS and MFS, (vii) pervasive cementation by iron oxide in shoreface-offshore and shoreface sandstones of TST immediately below the MFS, (viii) zeolites and palygroskite in shoreface sandstones of TST and HST, particularly above PB, and (ix) cementation by siderite in Gilbert-type deltaic sandstones of LST, tide-dominated deltaic and foreshore-shoreface sandstones of HST and in tide-dominated deltaic sandstones of TST, particularly at MFS. Moreover, this thesis revealed that the distribution of eogenetic alterations strongly control, and thus provide information for constraining the distribution patterns of mesogenetic alterations, such as illitization of mechanically infiltrated clays and dickitization of kaolinite, and hence of related reservoir quality evolution of sandstones during progressive burial.</p>

<p>This thesis constrains the distribution of diagenetic alterations and their impact on reservoir-quality and heterogeneity evolution pathways in relation to depositional environments and sequence stratigraphy (systems tracts and key sequence stratigraphic surfaces) of four selected paralic and shallow marine siliciclastic successions. </p><p>Typical eogenetic alterations encountered include the dissolution and kaolinitization of framework silicates, which are closely associated to shoreface facies of forced regressive systems tract (FRWST), lowstand systems tract (LST), upper part of the highstand systems tract (HST), and below the sequence boundary (SB). These alterations are attributed to incursion of meteoric water owing to rapid and considerable fall in the relative sea level. Extensive carbonate cementation is most evident below marine and maximum flooding surfaces (MFS), whereas dissolution of carbonate cement and detrital dolomite occur in LST, HST and below SB. Parameters controlling the patterns and texture (microcrystalline vs. poikilotopic) of calcite cement have been constrained within sequence stratigraphic framework of the sandstones. Coarse crystalline to poikilotopic calcite textures of meteoric water origin are thus closely linked to the FRWST, LST and upper part of the HST sandstones and occur mainly as stratabound concretions, whereas microcrystalline calcite, which was precipitated from marine porewaters, occurs as continuously cemented layers in the transgressive systems tract (TST) and lower part of the HST sandstones.</p><p>Eogenetic alterations impose, in turn, profound control on the distribution pattern of mesogenetic alterations, and hence on reservoir quality evolution (destruction vs. preservation) pathways of sandstones. Eogenetic infiltrated clays, which occur in the tidal estuarine TST and HST sandstones, have helped preserving porosity in deeply buried sandstone reservoirs (≈ 5 km) through inhibition of extensive cementation by quartz overgrowths. Other essential findings of this thesis include deciphering the control on the formation of authigenic illite and chlorite by ultra-thin (≤ 1 µm thick), grain-coating clay mineral substrate. </p>