This study provides the most updated stratigraphic, depositional and diagenetic histories of the Early Cretaceous Biyadh and Shu'aiba formations. Carbon isotope data were integrated with core descriptions and well logs to define the age model beyond the resolution of biostratigraphy; they were also used as a geochronology tool for correlating between wells and across platform to basin transitions. The Biyadh Formation consists of one 3rd-order sequence of four high-frequency sequences (S1-S4). S1 and S2 are the TST, composed of deep chalky limestone facies. S3 and S4 are the HST composed of skeletal rudist grainstone deposited in shallow water environments. The Biyadh sequence is capped by a regional subaerial boundary (SB1) corresponding to a global sea level fall. The Shu'aiba Formation consists of one 2nd-order sequence of four 3rd-order sequences and ten HFS's (S1-S10). S1 records the initial TST, followed by the regional MFS (K70) of S2. S3 is the late TST and is dominated by Lithocodium aggregatum/coral facies. S4 to S6 formed the early HST and are dominated by rudist buildups that transitioned basinward into fore-bank, slope and basinal settings with pronounced clinoform geometries. S7 and S8 are composed of shallow lagoonal milliolid packstone, representing the late HST. S9 and S10 are new identified Upper Aptian prograding sequences that formed during forced regression on the northern-block within platform edge and slope settings. The correlation between the Arabian Plate stratigraphic record and the standard Tethys isotope record and eustatic sea-level suggests a direct influence of the 3rd-order sea-level fluctuations on the Biyadh and Shu'aiba formations. This correlation also suggests that the Aptian were mainly controlled by glacio-eustatic fluctuations associated with eccentricity cycles. The Barremian records low magnitude sea-level changes and thinner sequences likely reflecting obliquity cycles. The Shu'aiba Formation records major subaerial hiatus reflecting glacial intervals, interrupted by flooding units reflecting global warming intervals. Trace elements, microprobe analysis, Cathodoluminescence (CL) and stable isotope data were used to define the diagenetic history of the Shu'aiba Formation within the sequence stratigraphic framework. The Shu'aiba Formation was mainly affected by meteoric diagenesis associated with the major unconformity at top of Shu'aiba.

The southern Campos Basin comprises syn- and post-rift strata characterised by thick and extensive units of non-marine limestones. These carbonate platforms are scientifically significant due to their unusual palaeoenvironmental setting, and the complexity of the factors controlling their accumulation. They are of economic importance due to discoveries of giant hydrocarbon accumulations in these non-marine carbonate rocks. 3D seismic interpretations show an oblique extensional rifting system that formed a series of graben, half-graben, accommodation zones and horsts oriented NESW to NNE-SSW. The area is subdivided into three tectonic domains based on structural style, stretching factors and subsidence rates. The structural template of the syn-rift exerts a strong influence on depositional patterns. Core logging and thin-section work together with FMI and sidewall core data indicate proximal to more distal lacustrine carbonate deposits with fluvio-deltaic clastics in marginal areas. The dominant carbonate facies are molluscan rudstones and floatstones and a taphonomic analysis (taphofacies) of the cored intervals and exposure surfaces indicate accumulation in shallowing-upward cycles in response to changes in lake level. Microbialite facies, Aptian in age, appear to occur in the most distal locations in restricted palaeoenvironmental conditions. Facies models are presented for the skeletal, mollusc-rich deposits of the Barremian Coqueiros Formation and the overlying microbialite-rich Aptian Macabu Formation. The deposits are stacked in a hierarchical arrangement of four levels of cyclicity ranging from the entire rift basin fill to metre-scale cycles. Controls on formation of these cycles include structural setting, climate and lacustrine margin progradation. Different types of carbonate platform form in the different basinal settings and include footwall areas of fault-blocks, accommodation zones and buried horst blocks. The southern Campos Basin evolves from an initial alkali lake (Barremian) to a main phase of syn-rift, brackish lake conditions. The post-rift succession (Aptian) is characterised by both brackish and hypersaline conditions.

A deposição aptiana da margem continental brasileira é caracterizada por dois elementos principais: 1) a presença de evaporitos (halita e/ou anidrita) num ambiente definido como lago-mar (de acordo com HSÜ, 1987); e 2) uma configuração tectonossedimentar do tipo sag. A chegada do mar às bacias, antes puramente continentais, é um evento que afeta toda a margem continental do Brasil, bem como tem ocorrência global. A sua presença nas bacias da margem equatorial , em particular, na Bacia Potiguar, possui um forte relacionamento com a existência de petróleo e gás (Bertani et al., 1989). A margem sudeste da Bacia Potiguar possui um razoável cobertura sísimica tanto 2D como 3D. As unidades estratigráficas compõe esta porção da bacia são a Formação Pendência, na base, a Formação Alagamar, a Formação Açu e no topo, a Formação Jandaíra. A Formação Pendência, na realidade mais um grupo do que formação, engloba as rochas depositadas na fase riftee da bacia (Della Favera et al., 1994). A Formação Alagamar envolve os sedimentos depositados no Aptiano, os quais estarão no foco deste trabalho; é formada por três membros: Upanema, Camadas Ponta de Tubarão e Galinhos (Della Favera, 1990). A Formação Açu, do Cretáceo Superior, separa-se discordantemente da seção da Formação Alagamar e é formada principalmente por arenitos fluviais. Esta formação transiciona para a Formação Jandaíra, denatureza carbonática, que constitui o topo da sequência sedimentar. Neste trabalho serão definidos os sistemas deposicionais e respectivos controles da sequência aptiana ao longo da borda sudeste da Bacia Potiguar a partir da identificação de eletrofácies e sismofácies. Sendo assim, nesta dissertação são mostradas as sequências de 3 e 4 ordem que representam, em conjunto, a Fm. Alagamar. Foram identificadas, em perfis elétricos de diferentes poços na área de estudo pelo menos 6 sequências de 4 ordem e 3 sequências de 3 ordem, que também foram identificadas em seções sísmicas arbitrária de direção SW-NE e SE-NW interligando os poços de etudo. A partir da análise dos dados e sequências identificadas, a reconstituiçãopaleoambiental apontou para ambiente de borda de lago (lago-mar) próxima a escarpa de falha, com depósitos de leques aluviais a delta de rios entrelaçados, praias com tempestitosareno-calcíferos, laguna salgada com formação de estromatólitos e eventuais solos carbonáticos. Sendo assim, as sequências de 3 ordem identificadas representariam cada um dos membros da Fm. Alagamar (Mb. Upanema, Mb. Ponta de Tubarão e Mb. Galinhos, da base para o topo). A correlação das sequências de 4 ordem identificadas pode ser aplicada no rastreamento de corpos arenosos, reservatórios de petróleo nessa porção da bacia. / The Aptian deposits of the Brazilian continental margin are characterized by two main elements: 1) the presence of evaporites (halite and / or anhydrite) in an environment defined as lake-sea (according to Hsu, 1987), and 2) a configuration of tectonossedimentar sag type. The arrival of the sea in basins before purely continental, is an event that affects the entire continental margin of Brazil, and has overall occurrence. Their presence in the equatorial margin basins, in particular in the Potiguar Basin, has a strong relationship with the existence of oil and gas (Bertani et al., 1989). The southeastern margin of Potiguar basin has a reasonable 2D and 3D seismic coverage. The stratigraphic units in this portion of the basin are Pendencia Formation at the base, Alagamar Formation, Acu Formation and at the top, Jandaíra Formation. The PendenciaFormation, includes rocks deposited during the rifte phase (Della Favera et al., 1994). The Alagamar Formation involves sediments deposited in the Aptian, which will be the focus of this work, consists of three members: Upanema, Layers Ponta de Tubarão and Galinhos (Della Favera, 1990). Acu Formation, Upper Cretaceous, separates the Alagamar Formation by an unconformity and it consists mainly of fluvial sandstones. The Jandaira Formation from transitional phase is represented by carbonates, which is the top of the sedimentary sequence. This work will define the depositional systems and their controls on Aptian sequence along the southeastern margin of the Potiguar basin Therefore, this dissertation shows the 3rd and 4th order sequences. These sequences, together, represent the AlagamarFm. The sequences were identified in electric logs from different wells in the studied area and at least 6 sequences of 4thand3 sequences of 3rdorder were identified for each well. These 3rd order sequences were also identified in arbitrary seismic sections (SW-NE and SE-NW directions).From the analysis of the data and the identified sequences the paleo-environmental reconstruction showed the edge of the lake (lakesea) near the Carnaubais fault zone. The reconstruction also showed, sandy beachtempestites and salty laguneswith stromatolites and carbonatic soils.Thus, the 3rd order sequences identified represent each member of Alagamar Fm. (Upanema Mb, Ponta de Tubarão Mb. And Galinhos Mb.from bottom to the top). The correlation of the 4th order sequences can be applied onidentification of sandy reservoirs in this part of the basin.

Processos diagenéticos controlam a porosidade e permeabilidade dos reservatórios de petróleo. Um estudo petrográfico sistemático de 71 arenitos e conglomerados da Formação Itabapoana (Aptiano), selecionadas de testemunhos de 13 poços na porção offshore da Bacia de Campos, Leste do Brasil, permitiu o reconhecimento dos principais constituintes primários, diagenéticos, tipos de poros e das relações temporais e espaciais entre eles. Essas rochas são contemporâneas aos extensos reservatórios lacustres do “Pré-Sal” atualmente em exploração. As rochas variam de arenitos muito finos a conglomerados, com predominância de arenitos muito grossos, e sua composição detrítica original corresponde a arcósios líticos e litarenitos feldspáticos, ricos em fragmentos de rochas vulcânicas (FRV). Argilominerais esmectíticos são os mais abundantes constituintes diagenéticos, relacionados principalmente à alteração de FRV, minerais pesados e biotita. A história térmica e de soterramento, e o fluxo de fluídos também exerceram um papel fundamental nos processos diagenéticos e na evolução da qualidade de reservatório. Os principais processos diagenéticos registrados foram a dissolução de FRV, feldspatos e minerais pesados, a autigênese de esmectitas, hematita, dolomita, calcita, zeolitas e óxidos de titânio cimentando e substituindo FRV, feldspatos, biotita e minerais pesados, a compactação mecânica e química, e a albitização dos feldspatos, principalmente dos plagioclásios. A porosidade primária intergranular foi fortemente reduzida pela compactação e cimentação por argilominerais esmectíticos, calcita, dolomita e zeolitas. Por outro lado, porosidade secundária foi gerada pela dissolução de constituintes primários e diagenéticos, e por faturamento. Futuros estudos específicos e detalhados, incluindo análises de microscopia eletrônica, difratometria de raios-X e isótopos estáveis, deverão contribuir para um melhor entendimento da distribuição espacial e temporal dos processos diagenéticos nessas rochas, de modo a embasar o desenvolvimento de modelos preditivos quanto à sua qualidade, que possam contribuir para reduzir os riscos envolvidos na sua exploração. / Diagenetic processes control the porosity and permeability of petroleum reservoirs. A systematic study of 71 sandstones and conglomerates of the Itabapoana Formation (Aptian), selected from the cores of 13 wells in the offshore portion of Campos Basin, eastern Brazil, allowed the recognition of the main primary and diagenetic constituents, pore types, and of the space and time relations among them. These rocks are contemporaneous to the extensive lacustrine Pre-Salt carbonate reservoirs under exploration. The rocks range from very fine-grained sandstones to conglomerates, with predominance of very coarse-grained sandstones, and their original detrital composition corresponds to lithic arkoses and feldspathic litharenites, rich in volcanic rock fragments (VFR). Smectitic clay minerals are the most abundant diagenetic constituents, related mostly to the alteration of VRF, heavy minerals and biotite. The burial and thermal history and the flow of fluids also exerted a fundamental role on the diagenetic processes and on the of reservoir quality. The main diagenetic processes recorded were the dissolution of volcanic fragments, feldspars and heavy minerals, the authigenesis of smectites, hematite, dolomite, calcite, zeolites and titanium oxides in intergranular pores and replacing VRF, feldspars, biotite and heavy minerals, mechanical and chemical compaction, and the albitization of feldspars, mostly plagioclase. Primary intergranular porosity was strongly reduced by compaction and smectite, calcite, dolomite and zeolite cementation. On the other hand, secondary porosity was generated by the dissolution of primary and diagenetic constituents, and by fracturing. Future specific and detailed studies, including electron microscopy, X-ray diffraction and stable isotope analyses, shall contribute to a better understanding of the space and time distribution of diagenetic processes in these rocks, in order to support the development of predictive models of their quality that may contribute to the reduction of risks involved in their exploration.

A deposição aptiana da margem continental brasileira é caracterizada por dois elementos principais: 1) a presença de evaporitos (halita e/ou anidrita) num ambiente definido como lago-mar (de acordo com HSÜ, 1987); e 2) uma configuração tectonossedimentar do tipo sag. A chegada do mar às bacias, antes puramente continentais, é um evento que afeta toda a margem continental do Brasil, bem como tem ocorrência global. A sua presença nas bacias da margem equatorial , em particular, na Bacia Potiguar, possui um forte relacionamento com a existência de petróleo e gás (Bertani et al., 1989). A margem sudeste da Bacia Potiguar possui um razoável cobertura sísimica tanto 2D como 3D. As unidades estratigráficas compõe esta porção da bacia são a Formação Pendência, na base, a Formação Alagamar, a Formação Açu e no topo, a Formação Jandaíra. A Formação Pendência, na realidade mais um grupo do que formação, engloba as rochas depositadas na fase riftee da bacia (Della Favera et al., 1994). A Formação Alagamar envolve os sedimentos depositados no Aptiano, os quais estarão no foco deste trabalho; é formada por três membros: Upanema, Camadas Ponta de Tubarão e Galinhos (Della Favera, 1990). A Formação Açu, do Cretáceo Superior, separa-se discordantemente da seção da Formação Alagamar e é formada principalmente por arenitos fluviais. Esta formação transiciona para a Formação Jandaíra, denatureza carbonática, que constitui o topo da sequência sedimentar. Neste trabalho serão definidos os sistemas deposicionais e respectivos controles da sequência aptiana ao longo da borda sudeste da Bacia Potiguar a partir da identificação de eletrofácies e sismofácies. Sendo assim, nesta dissertação são mostradas as sequências de 3 e 4 ordem que representam, em conjunto, a Fm. Alagamar. Foram identificadas, em perfis elétricos de diferentes poços na área de estudo pelo menos 6 sequências de 4 ordem e 3 sequências de 3 ordem, que também foram identificadas em seções sísmicas arbitrária de direção SW-NE e SE-NW interligando os poços de etudo. A partir da análise dos dados e sequências identificadas, a reconstituiçãopaleoambiental apontou para ambiente de borda de lago (lago-mar) próxima a escarpa de falha, com depósitos de leques aluviais a delta de rios entrelaçados, praias com tempestitosareno-calcíferos, laguna salgada com formação de estromatólitos e eventuais solos carbonáticos. Sendo assim, as sequências de 3 ordem identificadas representariam cada um dos membros da Fm. Alagamar (Mb. Upanema, Mb. Ponta de Tubarão e Mb. Galinhos, da base para o topo). A correlação das sequências de 4 ordem identificadas pode ser aplicada no rastreamento de corpos arenosos, reservatórios de petróleo nessa porção da bacia. / The Aptian deposits of the Brazilian continental margin are characterized by two main elements: 1) the presence of evaporites (halite and / or anhydrite) in an environment defined as lake-sea (according to Hsu, 1987), and 2) a configuration of tectonossedimentar sag type. The arrival of the sea in basins before purely continental, is an event that affects the entire continental margin of Brazil, and has overall occurrence. Their presence in the equatorial margin basins, in particular in the Potiguar Basin, has a strong relationship with the existence of oil and gas (Bertani et al., 1989). The southeastern margin of Potiguar basin has a reasonable 2D and 3D seismic coverage. The stratigraphic units in this portion of the basin are Pendencia Formation at the base, Alagamar Formation, Acu Formation and at the top, Jandaíra Formation. The PendenciaFormation, includes rocks deposited during the rifte phase (Della Favera et al., 1994). The Alagamar Formation involves sediments deposited in the Aptian, which will be the focus of this work, consists of three members: Upanema, Layers Ponta de Tubarão and Galinhos (Della Favera, 1990). Acu Formation, Upper Cretaceous, separates the Alagamar Formation by an unconformity and it consists mainly of fluvial sandstones. The Jandaira Formation from transitional phase is represented by carbonates, which is the top of the sedimentary sequence. This work will define the depositional systems and their controls on Aptian sequence along the southeastern margin of the Potiguar basin Therefore, this dissertation shows the 3rd and 4th order sequences. These sequences, together, represent the AlagamarFm. The sequences were identified in electric logs from different wells in the studied area and at least 6 sequences of 4thand3 sequences of 3rdorder were identified for each well. These 3rd order sequences were also identified in arbitrary seismic sections (SW-NE and SE-NW directions).From the analysis of the data and the identified sequences the paleo-environmental reconstruction showed the edge of the lake (lakesea) near the Carnaubais fault zone. The reconstruction also showed, sandy beachtempestites and salty laguneswith stromatolites and carbonatic soils.Thus, the 3rd order sequences identified represent each member of Alagamar Fm. (Upanema Mb, Ponta de Tubarão Mb. And Galinhos Mb.from bottom to the top). The correlation of the 4th order sequences can be applied onidentification of sandy reservoirs in this part of the basin.

Processos diagenéticos controlam a porosidade e permeabilidade dos reservatórios de petróleo. Um estudo petrográfico sistemático de 71 arenitos e conglomerados da Formação Itabapoana (Aptiano), selecionadas de testemunhos de 13 poços na porção offshore da Bacia de Campos, Leste do Brasil, permitiu o reconhecimento dos principais constituintes primários, diagenéticos, tipos de poros e das relações temporais e espaciais entre eles. Essas rochas são contemporâneas aos extensos reservatórios lacustres do “Pré-Sal” atualmente em exploração. As rochas variam de arenitos muito finos a conglomerados, com predominância de arenitos muito grossos, e sua composição detrítica original corresponde a arcósios líticos e litarenitos feldspáticos, ricos em fragmentos de rochas vulcânicas (FRV). Argilominerais esmectíticos são os mais abundantes constituintes diagenéticos, relacionados principalmente à alteração de FRV, minerais pesados e biotita. A história térmica e de soterramento, e o fluxo de fluídos também exerceram um papel fundamental nos processos diagenéticos e na evolução da qualidade de reservatório. Os principais processos diagenéticos registrados foram a dissolução de FRV, feldspatos e minerais pesados, a autigênese de esmectitas, hematita, dolomita, calcita, zeolitas e óxidos de titânio cimentando e substituindo FRV, feldspatos, biotita e minerais pesados, a compactação mecânica e química, e a albitização dos feldspatos, principalmente dos plagioclásios. A porosidade primária intergranular foi fortemente reduzida pela compactação e cimentação por argilominerais esmectíticos, calcita, dolomita e zeolitas. Por outro lado, porosidade secundária foi gerada pela dissolução de constituintes primários e diagenéticos, e por faturamento. Futuros estudos específicos e detalhados, incluindo análises de microscopia eletrônica, difratometria de raios-X e isótopos estáveis, deverão contribuir para um melhor entendimento da distribuição espacial e temporal dos processos diagenéticos nessas rochas, de modo a embasar o desenvolvimento de modelos preditivos quanto à sua qualidade, que possam contribuir para reduzir os riscos envolvidos na sua exploração. / Diagenetic processes control the porosity and permeability of petroleum reservoirs. A systematic study of 71 sandstones and conglomerates of the Itabapoana Formation (Aptian), selected from the cores of 13 wells in the offshore portion of Campos Basin, eastern Brazil, allowed the recognition of the main primary and diagenetic constituents, pore types, and of the space and time relations among them. These rocks are contemporaneous to the extensive lacustrine Pre-Salt carbonate reservoirs under exploration. The rocks range from very fine-grained sandstones to conglomerates, with predominance of very coarse-grained sandstones, and their original detrital composition corresponds to lithic arkoses and feldspathic litharenites, rich in volcanic rock fragments (VFR). Smectitic clay minerals are the most abundant diagenetic constituents, related mostly to the alteration of VRF, heavy minerals and biotite. The burial and thermal history and the flow of fluids also exerted a fundamental role on the diagenetic processes and on the of reservoir quality. The main diagenetic processes recorded were the dissolution of volcanic fragments, feldspars and heavy minerals, the authigenesis of smectites, hematite, dolomite, calcite, zeolites and titanium oxides in intergranular pores and replacing VRF, feldspars, biotite and heavy minerals, mechanical and chemical compaction, and the albitization of feldspars, mostly plagioclase. Primary intergranular porosity was strongly reduced by compaction and smectite, calcite, dolomite and zeolite cementation. On the other hand, secondary porosity was generated by the dissolution of primary and diagenetic constituents, and by fracturing. Future specific and detailed studies, including electron microscopy, X-ray diffraction and stable isotope analyses, shall contribute to a better understanding of the space and time distribution of diagenetic processes in these rocks, in order to support the development of predictive models of their quality that may contribute to the reduction of risks involved in their exploration.

Processos diagenéticos controlam a porosidade e permeabilidade dos reservatórios de petróleo. Um estudo petrográfico sistemático de 71 arenitos e conglomerados da Formação Itabapoana (Aptiano), selecionadas de testemunhos de 13 poços na porção offshore da Bacia de Campos, Leste do Brasil, permitiu o reconhecimento dos principais constituintes primários, diagenéticos, tipos de poros e das relações temporais e espaciais entre eles. Essas rochas são contemporâneas aos extensos reservatórios lacustres do “Pré-Sal” atualmente em exploração. As rochas variam de arenitos muito finos a conglomerados, com predominância de arenitos muito grossos, e sua composição detrítica original corresponde a arcósios líticos e litarenitos feldspáticos, ricos em fragmentos de rochas vulcânicas (FRV). Argilominerais esmectíticos são os mais abundantes constituintes diagenéticos, relacionados principalmente à alteração de FRV, minerais pesados e biotita. A história térmica e de soterramento, e o fluxo de fluídos também exerceram um papel fundamental nos processos diagenéticos e na evolução da qualidade de reservatório. Os principais processos diagenéticos registrados foram a dissolução de FRV, feldspatos e minerais pesados, a autigênese de esmectitas, hematita, dolomita, calcita, zeolitas e óxidos de titânio cimentando e substituindo FRV, feldspatos, biotita e minerais pesados, a compactação mecânica e química, e a albitização dos feldspatos, principalmente dos plagioclásios. A porosidade primária intergranular foi fortemente reduzida pela compactação e cimentação por argilominerais esmectíticos, calcita, dolomita e zeolitas. Por outro lado, porosidade secundária foi gerada pela dissolução de constituintes primários e diagenéticos, e por faturamento. Futuros estudos específicos e detalhados, incluindo análises de microscopia eletrônica, difratometria de raios-X e isótopos estáveis, deverão contribuir para um melhor entendimento da distribuição espacial e temporal dos processos diagenéticos nessas rochas, de modo a embasar o desenvolvimento de modelos preditivos quanto à sua qualidade, que possam contribuir para reduzir os riscos envolvidos na sua exploração. / Diagenetic processes control the porosity and permeability of petroleum reservoirs. A systematic study of 71 sandstones and conglomerates of the Itabapoana Formation (Aptian), selected from the cores of 13 wells in the offshore portion of Campos Basin, eastern Brazil, allowed the recognition of the main primary and diagenetic constituents, pore types, and of the space and time relations among them. These rocks are contemporaneous to the extensive lacustrine Pre-Salt carbonate reservoirs under exploration. The rocks range from very fine-grained sandstones to conglomerates, with predominance of very coarse-grained sandstones, and their original detrital composition corresponds to lithic arkoses and feldspathic litharenites, rich in volcanic rock fragments (VFR). Smectitic clay minerals are the most abundant diagenetic constituents, related mostly to the alteration of VRF, heavy minerals and biotite. The burial and thermal history and the flow of fluids also exerted a fundamental role on the diagenetic processes and on the of reservoir quality. The main diagenetic processes recorded were the dissolution of volcanic fragments, feldspars and heavy minerals, the authigenesis of smectites, hematite, dolomite, calcite, zeolites and titanium oxides in intergranular pores and replacing VRF, feldspars, biotite and heavy minerals, mechanical and chemical compaction, and the albitization of feldspars, mostly plagioclase. Primary intergranular porosity was strongly reduced by compaction and smectite, calcite, dolomite and zeolite cementation. On the other hand, secondary porosity was generated by the dissolution of primary and diagenetic constituents, and by fracturing. Future specific and detailed studies, including electron microscopy, X-ray diffraction and stable isotope analyses, shall contribute to a better understanding of the space and time distribution of diagenetic processes in these rocks, in order to support the development of predictive models of their quality that may contribute to the reduction of risks involved in their exploration.

An important episode of carbon sequestration, Oceanic Anoxic Event 1a (OAE-1a), characterizes the Lower Aptian worldwide, and is mostly known from deeper-water settings. The present work of two Lower Aptian deposits, Madotz (N Spain) and Curití Quarry (Colombia), is a multiproxy study that includes fossil assemblages, microfacies, X-ray diffraction bulk and clay mineralogy, elemental analyses (major, minor, trace elements), Rock-Eval pyrolysis, biomarkers, inorganic and organic carbon content, and stable carbon isotopes. The results provide baseline evidence of the local and global controlling environmental factors influencing OAE-1a in shallow-water settings. The data also improve our general understanding of the conditions under which organic-carbon-rich deposits accumulate. The sequence at Madotz includes four intervals (Unit 1; Subunits 2a, 2b and 2c) that overlap the times prior to, during and after the occurrence of OAE-1a. The Lower Unit 1(3m thick) is essentially siliciclastic, and Subunit 2a (20m) contains Urgonian carbonate facies that document abruptly changing platform conditions prior to OAE-1a. Subunit 2b (24.4 m) is a mixed carbonate-siliciclastic facies with orbitolinid-rich levels that coincides with OAE-1a δ13C stages C4-C6, and is coeval with the upper part of the Deshayesites forbesi ammonite zone. Levels with pyrite and the highest TOC values (0.4-0.97%), interpreted as accumulating under suboxic conditions, and are restricted to δ13C stages C4 and C5. The best development of the suboxic facies is at the level representing the peak of the transgression. Subunit 2c, within δ13C stage C7, shows a return of the Urgonian facies. The 23.35-m section at Curití includes a 6.3-m interval at the base of the Paja Formation dominated by organic-rich marlstones and shales lacking benthic fossils and bioturbation, with TOC values as high as 8.84%. The interval overlies a level containing reworked and phosphatized assemblages of middle Barremian to lowest Aptian ammonites. The range of values and the overall pattern of the δ13Corg (-22.05‰ to -20.47‰) in the 6.3m-interval is comparable with Lower Aptian δ13C stage C7. Thus, conditions of oxygen depletion at this site also occurred after Oceanic Anoxic Event-1a, which developed between carbon isotope stages C3 and C6. Both sites, Madotz and Curití, attest to the importance of terrigenous and nutrient fluxes in increasing OM productivity that led to episodic oxygen deficiency.

Les calcaires sont des roches sensibles aux phénomènes physiques et chimiques qui peuvent les dissoudre, les cimenter ou les fracturer. Dans ce cas, les propriétés des calcaires vont évoluer en fonction de ces différents processus qui varient dans le temps et dans l’espace. Or les réservoirs carbonatés peuvent s’étendre sur plusieurs centaines de kilomètres. Afin d’exploiter ces réservoirs géologiques (ressources en eau, gaz ou pétrole), il est donc nécessaire de caractériser en 3 dimensions leurs propriétés (porosité, perméabilité) ainsi que les hétérogénéités géologiques ou tectoniques, qui peuvent modifier la géométrie du réservoir ou ses propriétés. L’acquisition de données locales (affleurements, forages), réparties sur la totalité du réservoir, pose la question de leurs représentativités projetées sur l’ensemble du volume de roche mais aussi de leurs distributions entre les points d’acquisitions qui sont espacés de plusieurs kilomètres. Cette thèse propose d’étudier les propriétés des calcaires Urgoniens (d’âge Barrémien supérieur – Aptien inférieur) situés en Provence, analogues aux calcaires des réservoirs d’hydrocarbures présents au Moyen-Orient. Trois sites comportant différentes échelles sont étudiés afin de caractériser cette série carbonatée. L’étude propose ensuite des règles géologiques dans le but d’extrapoler les mesures réalisées sur des échantillons d’unités centimétriques à l’échelle hectométrique / Carbonates are sensitive to physical and chemical processes which can dissolve, cement or fracturing them. In this case, the carbonate properties evolve according to these different changes that vary in time and space. Carbonated reservoirs can extend for hundreds of kilometres. To prospect these geological reservoirs (water, gas or oil resources), it’s therefore necessary to characterize in 3 dimensions their properties (porosity, permeability), as well as geological and structural heterogeneities which can modify the basin geometry or the reservoir properties. The acquisition of local data (outcrops, boreholes) compared to the properties distributed at field scale ponder their representativeness at multi-kilometres scale but also their distribution between the acquisition area. This thesis proposes to study the properties of Urgonian limestones (Upper Barremian - Lower Aptian) located in Provence, analogue of Middle East hydrocarbon reservoirs. Three sites with different scales are studied to characterize this carbonate series. Additionally, this study proposes geological rules to upscale the measurements made on centimetric samples to hectometric scale

This study is a multi-proxy analysis of a 30-m section of a Barremian-Aptian succession of interbedded, grayish black (N2) and black (N1) limestones from a quarry of the Sierra de Prada. Index taxa include planktic foraminifera Globigerinelloides blowi and Hedbergella sigali, which combined with δ13C data from Cresmina and Gorgo a Cerbara sections indicate a late Barremian to early Aptian age. The rocks are organic-rich with 0.67 - 3.10 wt% total organic carbon (TOC). A marlstone interval (~1m) at 2.24 m has a low bioturbation index (1), TOC ~6.66 wt%, framboidal pyrite, and enrichment spikes of major, biolimiting, and redox-sensitive trace elements (Al, Si, Ti, P, Fe, and Mo, Cr, Cu, V, Th), indicating an anoxic episode. Biomarker analyses show a predominance of n-alkanes (≤nC20) at this level, suggesting an in situ origin of organic matter from phytoplankton. Pr/Phy ratios below 2 imply that organic matter did not reach overmaturity.