
Ángela FraguasRey Juan Carlos University | URJC · Biology and Geology
Ángela Fraguas
PhD in Geology
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55
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Introduction
Additional affiliations
June 2006 - May 2010
Education
October 2004 - July 2006
Publications
Publications (55)
The evolution of the coccolith genus Lotharingius was investigated in 18samples from the West Rodiles section (Asturias, Northern Spain), Upper Pliensbachian-Lower Toarcian in age. In each sample, the length and width of the coccolith and of its central area were measured on 150specimens of Lotharingius. A total of 2700specimens were measured, and...
Pelagic sediments from the subtropical South Atlantic Ocean contain geographically extensive Oligocene ooze and chalk layers that consist almost entirely of the calcareous nannofossil Braarudosphaera. Poor recovery and the lack of precise dating of these horizons in previous studies has limited the understanding of the number of acmes, their timing...
With the aim to understand prolonged and repeated marine anoxia after the Triassic-Jurassic mass- extinction event, a continuously cored, 338 metre thick succession of Rhaetian to Toarcian sediments was retrieved close to the village of Schandelah near Braunschweig (Lower Saxony, northern Germany). Here, preliminary biostratigraphical, lithological...
Quantitative analysis performed on latest Pliensbachian-early Toarcian calcareous nannofossil assemblages from the Camino section (Basque Cantabrian Basin), allowed to decipher their response to the environmental changes recorded during this time interval, characterized by an extinction event. The results were introduced within a principal componen...
El humedal de Carrizal Bajo, en la costa del Desierto de Atacama, es un
entorno árido con sedimentos arenosos posiblemente depositados por un
tsunami ocurrido en 1922 tras un gran terremoto de magnitud (Mw) 8,5-8,6.
El estudio de diatomeas se utiliza para la identificación de depósitos sedimentarios procedentes de eventos marinos de alta energía. S...
Three stratigraphic sections of the Betic External Zones were studied, two from the Median Subbetic (PEL and PR) and one from the External Subbetic (CE). The upper Pliensbachian materials and the transition to the lower Toarcian were dated with calcareous nannofossils in PEL and PR in this paper, while in the CE section, previous ammonite and nanno...
The early Toarcian was a time interval characterized by important environmental changes. A sharp warming was recorded, together with a negative carbon isotope excursion (CIE) in carbonates and organic matter, i.e., the Early Toarcian Oceanic Anoxic Event (T-OAE), and a superregional organic matter preservation interval (OMPI). All these factors led...
Las prácticas de campo son actividades presenciales donde los estudiantes aplican en el campo los conocimientos y habilidades adquiridos en el aula. En el caso de la geología, estas prácticas resultan esenciales en su formación, pues toman contacto con el objeto de estudio. En general, los recorridos que diseñan los profesores tienen en cuenta su i...
Three stratigraphic sections of the Betic External Zones have been studied, two from the Median Subbetic (PEL and PR) and one from the External Subbetic (CE). The upper Pliensbachian materials and the transition to the lower Toarcian have been dated with calcareous nannofossils in PEL and PR in this paper, while in the CE section, previous ammonite...
This paper studies ten Subbetic (Betic External Zones) stratigraphic sections spanning the Pliensbachian–early Toarcian time interval. Eight lithofacies were distinguished: crinoidal limestones, peloidal limestones, breccias, cherty limestones, nodular limestones, hardground surfaces and condensed levels, marls and marly limestone alternance, and d...
Drilling for the International Continental Scientific Drilling Program (ICDP) Early Jurassic Earth System and Timescale project (JET) was undertaken between October 2020 and January 2021. The drill site is situated in a small-scale synformal basin of the latest Triassic to Early Jurassic age that formed above the major Permian-Triassic half-graben...
The Mochras core, UK, an historic reference site for the study of Early Jurassic calcareous nannofossils, has been reinvestigated here across the Hettangian to Lower Pliensbachian. Both relative and absolute abundances of 24 calcareous nannofossil species reveal patterns and occurrences that define not less than 37 defined biohorizons. However, due...
On November 10th, 1922, at 23h 53m Chilean time, the Mw8.6 Atacama earthquake shook generating a highly destructive transoceanic tsunami with flood depths in the coastal cities near the epicenter of 7 to 9 m. There is no historical description of the tsunami arrival time to Carrizal Bajo (Atacama, Chile) but the chronicles report that two waves hit...
We are using calcareous nannofossils for dating the Colomera section, located at 400 m northeast to the Colomera village (Granada Province, Southern Spain). It belongs to the Median Subbetic (Betic Cordillera), and its Mesozoic materials were deposited in the South Iberian Paleomargin under hemipelagic conditions. This 42-m-thick section is part of...
A 95 m thick succession of grey siliceous limestone and marl on Mount Rettenstein in the Northern Calcareous Alps allowed us to study well-preserved and diverse radiolarian assemblages across the Sinemurian–Pliensbachian boundary. The distribution of 31 most characteristic radiolarian species is presented. Ammonites of the Jamesoni Subzone, the top...
Calcareous nannofossils are one of the main constituents of marly and carbonate lithologies, including common, recognizable, and widespread taxa. Therefore, they are one of the best biostratigraphic tools for dating rocks. This work gives new information about Lower Jurassic nannofossils from the Weitenhausgraben Cirque section (Austria), made up o...
Here, we present the results of a quantitative analysis performed on Pliensbachian calcareous nannofossil assemblages from the E Rodiles section (northern Spain), which allowed us to determine their changes in response to paleoenvironmental variations in a key connection between the Boreal and Tethyan realms. Nannofossil data are compared to publis...
Alrededor del límite Triásico/Jurásico tuvo lugar una de las cinco grandes extinciones masivas ocurridas en la historia de la Tierra. Esta se caracterizó por una intensa actividad volcánica de la Provincia Magmática del Atlántico Central (CAMP; Marzoli
et al., 2019), por rápidas fluctuaciones en el nivel del mar (Guex et al., 2016) y por importante...
The Palaeontological and Archaeological Museum “Ildefonso
Recio Valverde” was recently opened in Totanés (Toledo).
The material included in this museum mostly belonged
to the personal collection of I. Recio, who donated it to
this municipality to contribute to the dissemination of
Palaeontology and Archaeology. Its creation, and the even
more recen...
We have studied the latest Rhaetian-earliest Hettangian transition in a composite section, belonging to the Dürrnberg Formation and well-dated with ammonites, of the Hallstatt-Zlambach Basin (Northern Calcareous Alps, Austria), located in the Euroboreal outer shelf transitional to the Tethys Ocean. The first occurrence of the ammonite Psiloceras sp...
Calcareous nannofossil response to the paleoenvironmental changes recorded during the Early Toarcian has been deeply investigated during the last decade (Mattioli et al., 2008; Fraguas et al., 2012; Casellato et al., 2015; Clémence et al., 2015). However, there is still a great controversy about the mechanisms which led to the Early Toarcian nannof...
A total of 129 samples, Late Sinemurian-Pliensbachian in age, were collected from the well-dated and expanded E Rodiles section (Asturias, Northern Spain). 5 main events: the first occurrences (FOs) of Crepidolithus crassus, Similiscutum cruciulus, Biscutum novum, Lotharingius hauffii and Lotharingius sigillatus, were identified on the basis of con...
The Early Toarcian (Early Jurassic) was characterized by a significant seawater warming, a transgressive peak and a mass extinction event, which affected many different groups of marine organisms. Furthermore, major perturbations in the global carbon cycle were inferred based on the negative carbon isotope excursion recorded in bulk rock and organi...
A continuous record across the "Braarudosphaera chalks" was recovered from mid-Oligocene (~30-27Ma) deep-sea sediments in the subtropical South Atlantic Ocean and has been studied in detail. This stratigraphic section from ODP Site 1264 (Walvis Ridge) documents a succession of several chalky layers that consist almost completely of Braarudosphaera...
129 samples, Upper Sinemurian-Pliensbachian in age, were collected from the East Rodiles section, which is well-dated with ammonites and crops out in a coastal cliff located on the eastern part of the Rodiles Cape, in Asturias (Northern Spain). 5 main events: the first occurrences (FOs) of Crepidolithus crassus, Similiscutum cruciulus, Biscutum nov...
Los nanofósiles calcáreos son uno de los principales constituyentes de los sedimentos margosos y calcáreos del Mesozoico, e incluyen taxones comunes y fácilmente identificables tanto en el dominio Boreal como en el del Tethys (Bown y Cooper 1998; Mattioli y Erba 1999; Fraguas et al. 2015). Por estas razones, este grupo fósil es considerado una herr...
This paper provides a synthesis of the Upper Sinemurian–Lower Toarcian (Lower Jurassic) calcareous nannofossil biostratigraphy for the Cantabrian Range (Northern Spain), based on four sections from the Basque–Cantabrian Basin and one section from Asturias. Data derive from previously published bio -stratigraphic schemes and unpublished data, based...
The Early Jurassic epoch was a time of extreme environmental
change: there are well-documented examples of rapid
transitions from cold, or even glacial, climates to super
greenhouse events, the latter characterized worldwide by
hugely enhanced organic carbon burial, multiple large isotopic
anomalies, global sea-level change, and mass extinction
(Pr...
A comprehensive calcareous nannofossil zonation scheme for Lower Jurassic low- to mid-latitude sequences from NW Europe has been proposed by Bown & Cooper (1998), and it has been successfully applied in Italy and S France (Mattioli & Erba, 1999) and N Spain (Perilli et al., 2010). However, a detailed nannofossil zonation is currently not available...
Quantitative analysis of Late Pliensbachian-Early Toarcian calcareous nannofossil assemblages
from the West Rodiles section (Asturias, Northern Spain) has been performed in order to interpret
the palaeoenvironmental changes that occurred during this time interval, characterized by a major
extinction event. Nannofossil data were compared to the s...
Quantitative analysis of Late Pliensbachian-Early Toarcian calcareous nannofossil assemblages from the West Rodiles section (Asturias, Northern Spain) has been performed in order to interpret the paleoenvironmental changes that occurred during this time interval, characterized by a major extinction event, and especially around the Lower Toarcian Te...
Resumen: Los análisis cuantitativos de nanofósiles calcáreos del Pliensbachiense Superior-Toarciense Inferior de dos secciones de la Cordillera Cantábrica (norte de España), han permitido interpretar los cambios paleoambientales ocurridos durante este periodo, caracterizado por un evento de extinción masiva. Los datos obtenidos de la sección de O R...
Calcareous nannofossils represent one of the most important constituents of the
marly and carbonate lithologies, and include common and easily recognizable,
widespread taxa. For these reasons, nannofossils are considered a very helpful tool for
both biostratigraphy and paleoceanography.
In order to improve the knowledge about Late Sinemurian–Early...
Biometric analyses were performed on 20 Pliensbachian samples from the Santotis section (Basque-Cantabrian
Basin, N Spain), in order to separate the species Crepidolithus crassus and Crepidolithus crucifer based on their
size, and to evaluate the role, if any, of the paleoenvironmental conditions on C. crassus and C. crucifer size
changes. In each...
Based on calcareous nannofossil assemblages identified in four expanded and well-dated sections from the Basque-Cantabrian Basin, the main objective of this paper is to improve the knowledge of the Pliensbachian calcareous nannofossil events, and to calibrate these events to the ammonite zones established for this area. The semiquantitative analysi...
The target of this paper is to study the succession of the Pliensbachian calcareous nannofossil assemblages recovered from the Santotis section (Northern Spain) in order to calibrate the biohorizons against the ammonite zones. In this section, one hundred nineteen marly and carbonate-dominated levels have been recognized and forty-one of them have...
Se estudian los nanofósiles calcáreos identificados en materiales del Pliensbachiense de la sección de Tudanca (Cuenca Vasco-Cantábrica, España). Se han reconocido doscientos catorce niveles estratigráficos constituidos, fundamentalmente, por una alternancia de margas y calizas, de los que se han tomado un total de sesenta y cinco muestras. Se ha r...