CIM4-Vários
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Browsing CIM4-Vários by Author "Borges, Marisa"
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- Carbon isotope record (d13Ccarbonate) of the Middle to Late Jurassic (Callovian - Oxfordian) from the Algarve Basin, PortugalPublication . Borges, Marisa; Fernandes, Paulo; Rodrigues, Bruno; Goodhue, R.The Algarve Basin is an important Mesozoic depocentre located in southern Portugal which formed during the succesive phases of the North Atlantic rifting following the break-up of Pangea [1]. Several unconformities related to compressive episodes are observed in the stratigraphic record of the Algarve Basin. One of these episodes ocurred in the transition from Middle to Upper Jurassic times and is marked by an important tectonic episode, observed throughout Iberia [1], that caused the tilting and folding of the Middle Jurassic strata. This situation can be observed at Benaçoitão, where Oxfordian limestones rest unconformably over tilted Middle Callovian marly limestones. In this work we present !13Ccarbonate data across the Middle and Upper Jurassic rocks from the Algarve Basin at Benaçoitão.
- d13Ccarbonate chemostratigraphy of the Carrapateira Outlier (Lower Kimmeridgian), Southern PortugalPublication . Borges, Marisa; Goodhue, R.; Fernandes, Paulo; Pereira, Zélia; Matos, Vasco; Rodrigues, B.The Carrapateira Outlier (CO) located 20 km north of Sagres is formed by Upper Triassic to Kimmeridgian sediments. The studied section is located at Três Angras bay and consists of approximately 50 m of limestones interbedded with marls, assigned to the Early Kimmeridgian based on corals, foraminifera and dinoflagellate cysts. The uppermost limestone beds are rich in macrofossils with well-preserved corals in life position. To compile 13C chemostratigraphy for this section, sixty five bulk carbonate samples were studied.
- Jurassic palynostratigraphy of the Algarve Basin and the Carrapateira Outlier, Southern PortugalPublication . Borges, Marisa; Riding, James B.; Fernandes, Paulo; Pereira, ZéliaThe Mesozoic Algarve Basin (AB) corresponds to the southernmost geological province of mainland Portugal. The Carrapateira Outlier (CO) is a small outcrop of Mesozoic rocks located 20 km north of the AB. In this study we investigated the palynology of the Jurassic (Upper Bajocian to Lower Kimmeridgian) of the AB and CO.
- Jurassic Palynostratigraphy of the Sagres Region (Algarve Basin) and the Carrapateira Outlier: preliminary resultsPublication . Borges, Marisa; Fernandes, Paulo; Pereira, Zélia; Riding, James B.The Algarve Basin (AB) corresponds to the southernmost geological province of mainland Portugal. More than 3000m of essentially marine sediments accumulated during Mesozoic-Cenozoic times in the AB.
- Maturação orgânica da Bacia Algarvia. Resultados preliminares e implicações para a prospecção de hidrocarbonetosPublication . Fernandes, Paulo; Rodrigues, B.; Borges, Marisa; Matos, VascoA sondagem RUIVO-1, localizada na região imersa da Bacia Algarvia, foi estudada com a finalidade de se caracterizar o grau de maturação e conhecer as idades das unidades litológicas com base na bioestratigrafia dos dinoflagelados. O estudo do poder reflector da vitrinite indica que a sucessão do Mesozóico está matura em relação à “janela do petróleo”. Por outro lado, os dinoflagelados evidenciaram a presença de uma espessa sucessão do Caloviano, discordante sobre os depósitos evaporíticos do ?Triásico-Hetangiano. Um dinoflagelado característico do intervalo Toarciano-Aaleniano ocorre reciclado nos sedimentos do Caloviano. Este estudo é um contributo para melhorar o conhecimento da parte imersa da Bacia Algarvia e auxiliar em futuros trabalhos de prospecção de hidrocarbonetos.
- Maturação Orgânica da Bacia Mesozóica Algarvia (Sul de Portugal): implicações para a exploração de hidrocarbonetosPublication . Fernandes, Paulo; Matos, Vasco; Rodrigues, Bruno; Borges, Marisa; Clayton, GeoffA Bacia Algarvia (BA) situa-se no sul de Portugale apresenta uma direção principal E - O estando a sua parte emersa representada ao longo da costa, desde o Cabo de São Vicente até ao rio Guadiana, estendendo-se também para o offshore.
- Maturação orgânica e palinoestratigrafia da Sondagem RUIVO-1, região imersa da Bacia Algarvia. Contribuições para a prospecção de hidrocarbonetosPublication . Borges, Marisa; Fernandes, Paulo; Rodrigues, B.; Matos, VascoA sondagem RUIVO-1, localizada na região imersa da Bacia Algarvia, foi estudada com a finalidade de se caracterizar o grau de maturação e conhecer as idades das unidades litológicas com base na bioestratigrafia dos dinoflagelados.
- Middle-Upper Jurassic palynology of the Sagres region and the Carrapateira outlier: southern PortugalPublication . Borges, Marisa; Fernandes, Paulo; Pereira, Zélia; Riding, JimThe palynology of the Middle-Upper Jurassic fill of the Sagres region (Algarve Basin) and the Carrapateira outlier, southern Portugal was investigated. Samples were collected from Mareta beach, Cilheta beach and the Carrapateira outlier. Dinoflagellate cysts are confined to the Upper Bajocian to Upper Callovian sedimentary rocks exposed at Mareta and Cilheta beaches and the Lower Kimmeridgian strata of the Carrapateira outlier. The palynostratigraphical study of the Jurassic successions has yielded new biostratigraphical data based on dinoflagellate cysts and miospores. The results confirm, and in some cases refine, the existing macrofaunal age determinations of these successions.
- Miocene dinoflagellate cyst assemblages: preliminary correlation between the Lower Tagus and Algarve Basins (Portugal)Publication . Castro, Lígia; Borges, Marisa; Pereira, Zélia; Fernandes, Paulo; Pais, JoãoBiostratigraphic studies of several sections and a borehole (Belverde) of the Lower Tagus Basin, based on Miocene dinoflagellate cyst assemblages, have allowed a detailed stratigraphic investigation to be conducted. Assemblages are very diverse and abundant and can be used as important biostratigraphic guides. Recently, a palynostratigraphic study based on dinoflagellate cysts was conducted in two offshore wells, Ruivo-1 and Corvina, located in the Algarve Basin (southern Portugal). The recovered dinoflagellate assemblages are less abundant and diverse than those obtained in the Lower Tagus Basin. New inferences are made regarding the correlation between the dinoflagellate cysts known from the Lower Tagus Basin with the assemblages recently recovered from the Algarve Basin. Species of selected dinoflagellate cyst assemblages recovered are similar in both basins. Continuing progress with these new palynological studies and biostratigraphic data will help to refine knowledge of and correlations between Portuguese Miocene deposits.
- New palynological data from the Ruivo-1 and Corvina wells, offshore Algarve Basin, Portugal: implications for future hydrocarbon explorationPublication . Borges, Marisa; Riding, James B.; Fernandes, Paulo; Pereira, Zélia; Matos, VascoThe Algarve Basin is an important Mesozoic sedimentary basin located in southern Portugal. Its onshore part consists largely of marine carbonate sediments with more than 2000 m in thickness. The basin extends offshore where its geology is recognized seismically and a few hydrocarbon exploration wells were drilled in the mid 70’s and early 80’s. The palynostratigraphical study of two of these wells, Ruivo- 1 and Corvina, has yielded new biostratigraphical data based on dinoflagellate cysts. The Ruivo-1 well has a total depth of 2100 m and drilled a thick Callovian succession between 1800 and 2030 m. The samples from this interval yielded abundant organic residues that comprise well-preserved palynomorphs together with plant fragments. The dinoflagellate cysts assemblage include Batiacasphaera spp., Ctenidodinium sp., Ctenidodinium sellwoodii group, Ellipsoidictyum gochtii, Ellipsoidictyum/Valensiella group, Gonyaulacysta jurassica subsp. adecta, Impletosphaeridium spp., Korystocysta gochtii, Meiourogonyaulax caytonensis group, Pareodinia ceratophora, Sentusidinium spp., Systematophora areolata, Systematophora penicillata, Systematophora spp. and Tubotuberella dangeardii. This association is indicative of the Middle-Late Callovian. However, the presence in this interval of Nannoceratopsis deflandrei subsp. deflandrei, a Toarcian-Aalenian marker, suggesting reworking. The Corvina well cored a 2700 m thick succession of Miocene to Upper Jurassic sediments. Samples collected between 1595 and 2680 m yielded relatively abundant organic residues dominated by dinoflagellate cysts. The pollen associations are of low diversity and include bisaccate pollen, Callialasporites dampieri, Callialasporites turbatus, Callialasporites spp., Classopollis classoides and Perinopollenites elatoides. The dinoflagellate cyst floras from these samples are indicative of the ?Early-Middle Oxfordian due principally to the occurrence of Ctenidodinium ornatum, Compositosphaeridium polonicum, Hystrichosphaerina orbifera, Endoscrinium luridum, Gonyaulacysta jurassica subsp. jurassica, Rigaudella aemula, Surculosphaeridium vestitum, Stephanelytron redcliffense, Systematophora spp. and Wanaea acollaris. The dinoflagellate cyst assemblages from the two wells are less diverse than typical Callovian-Oxfordian associations from further north in Europe. The results are also consistent with the onshore Algarve Basin and could be explained by the partially enclosed nature of the Algarve Basin during Jurassic times. This new biostratigraphical data will help to refine the time calibration of the available seismic lines and help in future hydrocarbon exploration work.