Person: Canales Fernández, María Luisa
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First Name
María Luisa
Last Name
Canales Fernández
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Geológicas
Department
Geodinámica, Estratigrafía y Paleontología
Area
Paleontología
Identifiers
6 results
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Item El mar subtropical del Jurásico en Guadalajara(Geología de Guadalajara, 2008) Gómez Fernández, Juan José; Canales Fernández, María Luisa; Calonge García, María Amelia; Rodríguez Martínez, MartaItem Foraminifera from the Aalenian and the Bajocian GSSP (Middle Jurassic) of Murtinheira section (Cabo Mondego, West Portugal): Biostratigraphy and paleoenvironmental implications(Marine micropaleontology, 2008) Canales Fernández, María Luisa; Henriques, María Helena PaivaThe detailed study of benthic foraminifera in 28 samples from Late Toarcian–Aalenian–Early Bajocian hemipelagic sediments of the Murtinheira section (Cabo Mondego, Lusitanian Basin, West Portugal), has permitted the recognition of the assemblage composition and the analysis of their evolution throughout this time interval. The representatives of the Suborder Lagenina dominate all the assemblages and, in the majority of them, the most abundant species is Lenticulina münsteri. The Late Toarcian and Early Aalenian assemblages are very similar. From the Comptum Subzone, a gradual replacement of the Early Jurassic forms by characteristic Middle Jurassic taxa takes place. During the Late Aalenian–Early Bajocian interval, a significant number of last occurrences (LOs) of taxa are recorded. The assemblages composition, the estimation of the relative taxa abundances and the data obtained from the calculation of several diversity indexes, together with the previous sedimentological and paleontological works in this area, indicate that these assemblages were developed in a shelfal basin environment. This platform showed normal marine salinity values, good oxygenation and was always located above calcite compensation depth (CCD). However, the environmental conditions were not always the best for the development of rich and diverse foraminiferal assemblages. These conditions were probably unstable during the Late Toarcian (Aalensis Subzone)–Early Aalenian (lower part of the Comptum Subzone). From the Comptum Subzone to the lower part of the Limitatum Subzone (Late Aalenian), conditions were more stable and more favourable for the development of foraminiferal communities. However, in the Aalenian–Bajocian transition the environmental conditions changed again and affected the development of this group. In the Limitatum Subzone a decrease in the diversity of the assemblages was recorded. This fact seems to be related to a global perturbation in the carbon-cycle that could have affected the foraminifera, together with other marine and continental organism groups.Item Ostracods from the global stratotype section for de base of the Aalenian stage, Jurassic, at Fuentelsaz section (Cordillera Ibérica, Spain)(Rivista italiana di paleontologia e stratigrafia, 2009) Arias Fernández, María Del Carmen; García Frank, Alejandra; Canales Fernández, María Luisa; Ureta Gil, María SoledadThe Toarcian/Aalenian Global Stratotype Section and Point (GSSP) have been recently placed in the Fuentelsaz section, northeastern Spain. This paper is part of a long-term project that attempts to describe for the first time the fossil ostracod assemblages present in the Toarcian-Aalenian boundary GSSP, and to assess their palaeobiogeographical significance. The study of the Late Toarcian-Early Aalenian Turmiel and Casinos formations at the Fuentelsaz section has produced a detailed stratigraphy and a large collection of stratigraphically constrained ostracod faunas. Twenty benthic ostracod species have been identified and for the first time described in Spain. Higher part of the Mactra Subzone, Late Toarcian, have yielded abundant ostracod faunas, including mostly species of the genera Praeschuleridea, Cytherelloidea and Kinkelinella; fossiliferous marls of the Late Toarcian and part of the Early Aalenian and poorly fossiliferous marls at the beginning of the Opalinum Zone are dominated by Praeschuleridea and Cytherelloidea. The boundary between the Toarcian and Aalenian is not characterized by any radical change in the ostracod faunal composition. The Fuentelsaz sequence exhibits ostracod assemblages comparable to those recorded in western Europe, with many of their species having similar stratigraphical distributions.Item Seawater temperature and carbon isotope variations in belemnites linked to mass extinction during the Toarcian (Early Jurassic) in Central and Northern Spain. Comparison with other European sections(Palaeogeography, palaeoclimatology, palaeoecology, 2008) Gómez Fernández, Juan José; Goy Goy, Antonio; Canales Fernández, María LuisaThe Early Toarcian mass extinction marks one of the critical events in the history of the Earth. Many of these events have been linked to important climate changes. Two sections of the Toarcian showing high-resolution ammonite-based biostratigraphy are studied in Central and Northern Spain. Stable isotope datasets, based on the analysis of 192 diagenetically screened belemnite calcite and 41 bulk carbonates, allowed the construction of δ13C curves and a δ18O-based palaeotemperature. Comparison of the extinction pattern with other sections in Europe and northern Africa shows that the Early Toarcian mass extinction boundary occurred at the Tenuicostatum–Serpentinum transition, and that the organic-rich facies linked to the Oceanic Anoxic Event and the associated negative δ13C excursion are diachronous. From a latest Pliensbachian cooling interval, a first increment of seawater temperature averaging about 4.5 °C, started around the Pliensbachian–Toarcian boundary and developed during the earliest Toarcian Tenuicostatum Biochron, marking the beginning of the main extinction interval. From the Tenuicostatum–Serpentinum transition up to the Bifrons Biochron, a rise in seawater temperature averaging 5.7 °C to 7.8 °C was recorded. This warming interval, which started rapidly and which seems to be synchronous at least in Western Europe, is considered one of the main factors responsible for mass extinction. For some authors this rapid warming was probably due to a massive injection of greenhouse gases into the atmosphere, but it does not seem to be recorded in belemnite calcite, and the origin of these possible gases is largely debated in the literature. Additional isotope excursions were found in the studied sections in Spain during the Middle and Late Toarcian. A negative δ13Cbel excursion has been recorded at the latest Bifrons Biochron. Above this shift, the Illustris–Vitiosa subzones thermal peak, which represents a 2–3 °C ΔT, could be linked to one of the tectonomagmatic activity peaks recorded in the Karoo Basin. A renewal in the ammonite and brachipod faunas coincident with this climatic change has been recognized in NW Europe and Western Tethys. An interesting thermal peak has also been detected in belemnites of the Insigne Subzone. ΔT is in the order of 3 °C, and in both sections the thermal peak is included into a δ13Cbel negative excursion of about −1.5‰. Relative synchrony with the new age for the Karoo main magmatic activity (178–180 Ma) indicates that the δ13C negative anomaly and the warming interval could be caused by the release of volcanogenic greenhouse gases. At this short interval, noteworthy changes in the abundance and diversity of the recorded assemblages in several faunal groups of NW Europe and Tethys are observed. The uppermost Levesquei Subzone thermal peak has only been recognized in the deposits of the section located in Central Spain and coincides with a positive δ13C excursion.Item Palaeoclimatic and biotic changes during the Aalenian (Middle Jurassic) at the southern Laurasian Seaway (Basque–Cantabrian Basin, northern Spain)(Palaeogeography, palaeoclimatology, palaeoecology, 2009) Gómez Fernández, Juan José; Canales Fernández, María Luisa; Ureta Gil, María Soledad; Goy Goy, AntonioThe uppermost Toarcian–lowermost Bajocian deposits have been studied in 10 sections located in the western part of the Basque–Cantabrian Basin (northern Spain). The studied 276 successive recorded ammonite assemblages allowed detailed biostratigraphical subdivision and the correlation of the sections at the ammonite zone and subzone scale. The foraminifers were studied in 96 samples and 55 diagenetically screened belemnite rostra were analyzed for C and O isotope. Facies and thickness distribution of the Aalenian sediments suggest that deposition took place in a nearly symmetrical sub-basin included into an intraplate shallow platform, developed over continental crust, on which flexure was the main control responsible for subsidence and basin evolution. Noteworthy negative δ13Cbel excursions, coinciding with seawater temperature changes, were recorded during the Bradfordensis Biochron, around the Concavum–Limitatum biochron boundary, and around the Aalenian–Bajocian boundary. A close relationship between the changes in seawater temperature and the biotic changes observed in the foraminiferal and in the ammonoids assemblages has been evidenced. During the Comptum Biochron, the δ18Obel-based palaeotemperature shows a remarkable cooling interval with an average seawater temperature of 15.7 °C. This cooling favoured the immigration of species of foraminifers that thrived in platforms with colder seawater temperatures located north of the Basque–Cantabrian Basin. As a consequence, a strong increase in the diversity of the foraminiferal assemblages (28.5% of first appearances) occurred. This interval also coincides with the highest ammonoid abundance recorded during the Aalenian. A notable increase in temperature with peak values up to 24.3 °C, was measured during the Bradfordensis Biochron. This warming marks the beginning of progressive loss of foraminifer diversity and the decrease in the abundance of ammonoids. However, the increase in the relative abundances of some foraminiferal taxa such as the genus Spirillina during the warming phase is remarkable. Some of the foraminiferal species that had their last occurrence during this interval seem to be immigrants from NW Europe that arrived during the Comptum cooling interval, and that did not survive to rise of the seawater temperature. Another drop in temperature was recorded during the late Gigantea and the early Concavum biochrons. Coinciding with this cooling interval nearly 20% of the foraminiferal species disappeared while the ammonoid abundance increased. A new and significant warming episode occurred during the latest Aalenian (Limitatum Biochron), extending to the earliest Bajocian (Discites Biochron). Biotic response to this new ΔT of 2.5 °C is remarkable, marking one of the most important crises of the Aalenian. More than 30% of the foraminiferal species disappeared and no new appearances were recorded. Ammonoids show a decrease in the specimen abundance during the Limitatum–Discites warming, preceding a drastic decrease in the species abundance. The remarkable biotic changes linked to the variations of seawater temperature recorded in the Basque– Cantabrian Basin during the Aalenian, open the possibility that some of these faunal turnovers, specially marked in the benthic foraminifers, were of global extent and mainly forced by climate changes.Item The Global Boundary Stratotype Section and Point (GSSP) of the Toarcian-Aalenian Boundary (Lower-Middle Jurassic)(Episodes, 2001) Cresta, S.; Goy Goy, Antonio; Ureta Gil, María Soledad; Arias Fernández, María Del Carmen; Barrón López, Eduardo; Bernard García, Julio; Canales Fernández, María Luisa; García Joral, Fernando; García Romero, Emilia; Gialanella, P.R.; Gómez Fernández, Juan José; González, J.A.; Herrero Matesanz, M. De La Concepción; Martínez Gutiérrez, Gemma; Osete López, María Luisa; Perilli, Nicola; Villalaín, J.J.The Global Boundary Stratotype Section and Point (GSSP) for the Aalenian Stage, formally defined at the base of bed FZ107 in the Fuentelsaz section, Castilian Branch of the Iberian Range (Spain), has been ratified by the IUGS. Multidisciplinary biostratigraphical data, based on ammonites, brachiopods, ostracods, bivalves, foraminifera, calcareous nannofossils assemblages and palynomorphs, assure worldwide correlations; magnetostratigraphic data increase this correlation power. The position of the boundary coincides with the first occurrence of the ammonite assemblage characterized by Leioceras opalinum and Leioceras lineatum and corresponds with a normal polarity interval correlated with the up-to-date Jurassic magnetic polarity time scale (Gradstein and others, 1994; Ogg, 1995).