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- The age of the first pulse of continental rifting associated with the breakup of Pangea in Southwest Iberia: new palynological evidencePublication . Vilas Boas, Margarida; Paterson, Niall W.; Pereira, Zélia; Fernandes, Paulo; Cirilli, SimonettaIn this work, we report the first palynological age for the base strata of the Silves Sandstones of the Silves Group in the Algarve Basin, located in Southern Portugal. The group is the oldest sedimentary unit of the Algarve Basin and was deposited unconformably over late Pennsylvanian turbidites of the Mira Formation, which were folded and faulted during the Variscan Orogeny. The Silves Group comprises a detrital red bed succession, representing the earliest phase of sedimentation associated with the initial rifting of Pangaea. Macrofossils are rare, occurring predominantly in the top layers of this group, and do not accurately constrain the age of the entire group's deposition. From an outcrop exposed in the central Algarve, a grey mudstone bed positioned 2.5 m above the Variscan unconformity plane yielded palynomorphs that date the beginning of sedimentation in this basin to the early Carnian age (Late Triassic). The moderately well preserved and low-diversity palynological association comprises Aulisporites astigmosus, Enzonalasporites densus, Ovalipollis pseudoalatus, Samaropollenites speciosus, Tulesporites briscoensis and Vallasporites ignacii, among others, and is indicative of an early Carnian age.
- Callovian (Middle Jurassic) dinoflagellate cysts from the Algarve Basin, southern PortugalPublication . Borges, Marisa; Riding, James B.; Fernandes, Paulo; Matos, Vasco; Pereira, ZéliaThe palynology of three Callovian (Middle Jurassic) limestone-marl successions from the Algarve Basin in southern Portugal was studied. These localities are Baleeira Harbour, Mareta Beach and Telheiro Quarry; they provide a composite. succession, tied to ammonite zones, through the Lower, Middle and Upper Callovian from the western and eastern subbasins of the Algarve Basin. The three sections generally yielded relatively abundant marine and continental palynofloras. Diversity is low to moderate and the dinoflagellate cyst associations are dominated by Ctenidodinium spp., the Ellipsoidictyum/Valensiella group, Gonyaulacysta jurassica subsp. adecta, Korystocysta spp., Meiourogonyaulax spp., Pareodinia ceratophora, Sentusidinium spp., Surculosphaeridium? vestitum and Systematophora spp. Some intra-Callovian marker bioevents were recorded; these include the range bases of Ctenidodinium ornatum, Gonyaulacysta eisenackii, Korystocysta pachyderma, Mendicodinium groenlandicum, Rigaudella spp. and Surculosphaeridium? vestitum. The occurrences of Endoscrinium acroferum and Impletosphaeridium varispinosum in the Early to Middle Callovian of Mareta Beach and Telheiro Quarry are also characteristic of this interval. At Baleeira Harbour, the presence of Ctenidodinium continuum and Gonyaulacysta centriconnata in the Peltoceras athleta Zone confirms the Late Callovian age of this section. The successions studied were deposited in restricted infralittoral neritic marine environments which lack deep water circulation, and possibly represent restricted embayments. The relatively low diversity nature of the dinoflagellate cyst assemblages appears to be largely due to the highly enclosed nature of this depocentre. Many Callovian index dinoflagellate cyst taxa which are found in northwest Europe are absent in the Algarve Basin. These forms may have been intolerant of enclosed palaeoenvironments which have restricted or no deep circulation. The Callovian marine palynofloras from the Algarve Basin compare well to the few other published records from the Iberian Peninsula of this age. However they are significantly less diverse than coeval floras from elsewhere in the extensive Mid Latitude Callovian phytoprovince. Many typically Callovian dinoflagellate cysts are cosmopolitan, however some provincialism is clearly manifested. The Arctic and Austral Callovian phytoprovinces are characterised by key endemic taxa such as Paragonyaulacysta retiphragmata and Ternia balmei, which are not present in the Algarve Basin and are assumed to have been polar forms.
- New palynostratigraphic data of the Irati (Assistencia Member) and the Corumbatai formations, Parana Basin, Brazil, and correlation with other south American basinsPublication . Rocha, H., V; Mendes, M.; Pereira, Z.; Rodrigues, C.; Manuel Carvalho Fernandes, Paulo; Lopes, Gilda; Sant'Anna, L. G.; Tassinari, C. C. G.; Lemos de Sousa, M. J.This research presents the palynostratigraphy of organic-rich shales from the Irati and the Corumbatai formations, Parana Basin (PB), Southeastern Brazil, as part of an unconventional hydrocarbon source rock and CO2 reservoir assessment study. Thirty-four samples from the Corumbatai Formation and the Assistencia Member of the Irati Formation were collected in the states of Goias (northern border of the PB), Sao Paulo and Parana (eastern and southern border of the PB, respectively). The acquired data allowed to establish a comprehensive palynostratigraphic study across the basin where a total of 18 pollen genera (34 pollen species), seven spore genera, four microplankton genera (1 species), and Chlorophyceae algae species where identified. The palynostratigraphic analysis also reveals a clear dominance of bisaccate pollen grains such as Corisaccites alutas, Lueckisporites virkkiae, and Weylandites lucifer. The Lueckisporites virkkiae zone was identified in the upper part of the Irati Formation (Assistencia Member) and the lowermost part of the Corumbatai Formation, indicating a Kungurian to Roadian age for this part of the succession. Differences in the Guttulapollenites hannonicus and Tornopollenites toreutos biostratigraphic ranges, recovered in the Corumbatai Formation, suggest an earlier development of these species in the Parana Basin during the middle Permian. Therefore, to evaluate the differences in the first occurrences of key species within the Parana Basin, a close palynostratigraphic correlation between the main Guadalupian-Lopingian South American Gondwana basins is tentatively established.
- A new approach to palynostratigraphy of the middle–late Famennian Gafo Formation, southern sector of the Pulo do Lobo Domain, SW Iberia (Portugal and Spain)Publication . Mendes, Márcia; Pereira, Zélia; Vaz, Nuno; Díez-Montes, Alejandro; Matos, João X.; Albardeiro, Luis; Manuel Carvalho Fernandes, Paulo; Jorge, Raul; Chew, DavidNew palynological results from the Gafo Formation (southern sector of the Pulo do Lobo Domain, South Portuguese Zone) are integrated with recently studied sections and drillholes from the Portuguese and Spanish sectors. A total of 44 samples were studied, 27 of which were positive for palynomorph taxonomy. This research revealed well preserved palynological assemblages, including 73 spore species allocated to 28 genera, four acritarch genera, three prasinophyte algae genera plus common chitinozoan remains. Some additional forms were retained under open nomenclature. From this, the first complete age determination for the Gafo Formation in Portugal and Spain was achieved, indicating a middle Famennian (Grandispora gracilis–Grandispora famenensis, GF Biozone) to a late Famennian (Grandispora echinata, VH Biozone) age. A greywacke sample from the same Gafo Formation was dated by U–Pb zircon geochronology and a maximum depositional age of 369 ± 2.5 Ma was obtained. A correlation between these palynological and U–Pb zircon data and the palynoflora assemblages of previous authors was made, as well as with the ages of felsic volcanic rocks found intercalated in the Gafo Formation, confirming the complex stratigraphy of Pulo do Lobo Domain. The results are consistent with stratigraphic mapping and structural interpretations, allowing a middle–late Famennian age (GF and VH Biozone) to be assigned to the Gafo Formation sedimentary rocks. This work has also contributed to a reinterpretation of Gafo Formation depositional facies correlatives (e.g. the Santa Barbara Group in Spain) as being the same lithological unit.
- Upper barremian−lower aptian charophyte biostratigraphy from arrifes section (Algarve Basin, Southern Portugal): correlation with dinoflagellate cyst biostratigraphyPublication . Pérez-Cano, Jordi; Pereira, Hélder; Mendes, Marcia; Pereira, Zélia; Callapez, Pedro Miguel; Fernandes, PauloThe Arrifes section (Algarve Basin, Southern Portugal) has been studied from the viewpoint of char-ophyte biostratigraphy. The previous sedimentological studies in this section showed that it is built of the interbedding of continental and marine facies that contain both marine and continental palynomorphs (pollen, spores, and dinoflagellates), providing an excellent sedimentary context to perform direct cor-relations between marine and continental domains. In the present work, the identified charophyte biozones have been correlated with dinoflagellate biozones previously recognized in the Arrifes section, being the first time that these two biochronologies can be directly correlated. From the charophyte biostratigraphy viewpoint, two assemblages are distinguished. The older one is found between 65 and 135 m of the stratigraphic section, and it is composed of the species Echinochara lazarii, Atopochara trivolvis var. triquetra, A. trivolvis var. trivolvis, Clavator grovesii var. jiuquanensis, Clavator harrisii var. harrisii, C. harrisii var. reyi, and C. harrisii var. zavialensis. This assemblage belongs to the upper Barremian -lower Aptian Clavator grovesii var. jiuquanensis Eurasian biozone and also to the Ascidiella cruciata-Pseudoglobator paucibracteatus European biozone and it is described in beds with the dinoflagellate cyst Subtilisphaera scabrata (lower to lowermost upper Barremian) and Odontochitina operculata (from upper Barremian upwards). The younger charophyte assemblage is found between 135 and 155 m of the stratigraphic section, and it is composed of the species A. trivolvis var. trivolvis, Clavator grovesii var. corrugatus, Clavator harrisii var. harrisii, C. harrisii var. reyi, and C. harrisii var. zavialensis. This assemblage belongs to Clavator grovesii var. corrugatus biozone, previously assigned to upper Aptian (Clavator grovesii var. lusitanicus biozone). However, in the Arrifes section, this assemblage is found in beds assigned to the dinoflagellate cyst Odontochitina operculata (from upper Barremian-lower Aptian). The direct correlation of the base of the C. grovesii var. corrugatus biozone with the dinoflagellate cyst O. operculata, indicates that the base of the Clavator grovesii var. corrugatus biozone is in the upper lower Aptian, which is slightly older than was previously suggested, and it is extended until the middle Albian.
- 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.
- New palynostratigraphic data of the irati (Assistência Member) and the corumbataí formations, Paraná Basin, Brazil, and correlation with other south American basinsPublication . Rocha, H. V.; Mendes, M.; Pereira, Z.; Rodrigues, C.; Fernandes, Paulo; Lopes, Gilda; Sant’Anna, L. G.; Tassinari, C.C.G.; Lemos de Sousa, M.J.This research presents the palynostratigraphy of organic-rich shales from the Irati and the Corumbataí formations, Paraná Basin (PB), Southeastern Brazil, as part of an unconventional hydrocarbon source rock and CO2 reservoir assessment study. Thirty-four samples from the Corumbataí Formation and the Assistência Member of the Irati Formation were collected in the states of Goiás (northern border of the PB), São Paulo and Paraná (eastern and southern border of the PB, respectively). The acquired data allowed to establish a comprehensive palynostratigraphic study across the basin where a total of 18 pollen genera (34 pollen species), seven spore genera, four microplankton genera (1 species), and Chlorophyceae algae species where identified. The palynostratigraphic analysis also reveals a clear dominance of bisaccate pollen grains such as Corisaccites alutas, Lueckisporites virkkiae, and Weylandites lucifer. The Lueckisporites virkkiae zone was identified in the upper part of the Irati Formation (Assistência Member) and the lowermost part of the Corumbataí Formation, indicating a Kungurian to Roadian age for this part of the succession. Differences in the Guttulapollenites hannonicus and Tornopollenites toreutos biostratigraphic ranges, recovered in the Corumbataí Formation, suggest an earlier development of these species in the Paraná Basin during the middle Permian. Therefore, to evaluate the differences in the first occurrences of key species within the Paraná Basin, a close palynostratigraphic correlation between the main Guadalupian-Lopingian South American Gondwana basins is tentatively established.
- First record of Permo-Triassic palynomorphs of the N'Condedzi sub-basin, Moatize-Minjova Coal Basin, Karoo Supergroup, MozambiquePublication . Galasso, Francesca; Pereira, Zelia; Manuel Carvalho Fernandes, Paulo; Spina, Amalia; Marques, JoaoPermian-Triassic ages have been identified for the first time in the Karoo Supergroup of the N'Condedzi sub-basin, Moatize-Minjova Coal Basin, Mozambique. This transition was identified in a coal exploration borehole that penetrated the Matinde and Cadzi formations. The top of the Matinde Formation is dated latest Permian (Lopingian), and the Cadzi Formation is attributed to Triassic based on palynostratigraphy. The Lopingian age is established by the identification of three palyno-assemblages: Assemblage L1 based on the first occurrence (FO) of Guttulapollenites pollen, Assemblage L2 is marked by the FO of Thymospora pseudothiessenii, and Assemblage L3 is defined by the FO of Osmundacidites senectus. Triassic palynomorphs were identified for the first time in Mozambique (Karoo basins). The data allowed the identification of three assemblages: Assemblage T1 defined by the FO of Densoisporites nejburgii of Induan age, Assemblage T2 is marked by the FO of Platysaccus queenslandi and assigned to the Olenekian age, and Assemblage T3 is defined by the FO of Samaropollenites speciosus and Enzonalasporites vigens, indicating a Carnian age. No Middle Triassic rocks were identified, and the early Triassic sediments are overlain by sedimentary rocks of Carnian age, a hiatus that may correspond to an important tectonic event with uplift and erosion. This tectonic event is also suggested by the occurrence of common reworked Permian palynomorphs in the Carnian sedimentary rocks. These new data constrain the age of the Karoo Supergroup formations of Mozambique and contribute to improve the palaeoecological, palaeoclimatic evolution, and the palaeogeographic position of the Karoo Mozambique basins within the Gondwana supercontinent. (C) 2019 Elsevier Masson SAS. All rights reserved.
- Palynology of the kingscourt outlier (Ireland)Publication . Fernandes, Paulo; Clayton, GeoffThe Kingscourt Outlier occupies a roughly triangular area on the southern part of the Lower Palaeozoic Longford–Down Massif in eastern Ireland. It comprises a condensed succession of sedimentary rocks that record the onset of fluvio‐deltaic sedimentation across eastern Ireland during Late Viséan to Late Bashkirian (Jackson, 1955, 1965). The outlier forms a syncline structure with an axis orientated approximately north‐south and parallel with the normal Kingscourt Fault that downthrows beds of Carboniferous and Permo‐Triassic age against the Lower Palaeozoic rocks.
- The Jurassic (Pliensbachian to Kimmeridgian) palynology of the Algarve Basin and the Carrapateira outlier, southern PortugalPublication . Borges, Marisa; Riding, James B.; Fernandes, Paulo; Pereira, ZéliaThe palynology of the Jurassic (Upper Pliensbachian to Lower Kimmeridgian) fill of the Algarve Basin and the Carrapateira outlier, southern Portugal was investigated. Samples were collected from Armação Nova Bay, Mareta Beach, Cilheta Beach and the Carrapateira outlier. At Armação Nova Bay the Upper Pliensbachian–Lower Toarcian succession proved barren, or yielded sparse, non age-diagnostic palynomorphs. 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. At Mareta Beach, the Upper Bajocian, Bathonian and Callovian produced relatively low to moderate diversity dinoflagellate cyst assemblages. Several key bioevents confirm the Bathonian and Callovian ages of the succession; no age-significant Late Bajocian bioevents were noted. The Upper Callovian of Cilheta Beach yielded moderately diverse dinoflagellate cyst associations dominated by Ctenidodinium spp. Key Late Callovian bioevents confirm the age of this succession. Many familiar marker forms known from northwest Europe were not encountered. No typically Arctic forms were recovered throughout the Upper Bajocian to Callovian of this part of the Algarve Basin. It is clear that there was no significant Late Bajocian to Late Callovian dinoflagellate cyst provincialism within southern and northern Europe and adjacent regions. The Carrapateira outlier yielded a moderately diverse Early Kimmeridgian dinoflagellate cyst flora. The Early Kimmeridgian age assessment based on corals and foraminifera is confirmed. Amphorula and Histiophora are present; these are typical of the Late Jurassic of the Tethyan Realm, and their presence is consistent with Late Jurassic provincialism within Europe. The relatively low diversity nature of these Late Bajocian to Early Kimmeridgian dinoflagellate cyst floras is probably mainly due to the relatively deep water, partially enclosed depositional setting. The partially enclosed nature of this part of the Algarve Basin and the Carrapateira outlier seems to have prevented the free migration of dinoflagellates between southern Portugal and elsewhere in Europe.