Modelización del cambio de la línea de costa en la comarca del Bajo Segura (Sinus Ilicitanus, S provincia de Alicante) en los últimos 15.000 años

Durante varios años los equipos de Geofísica marina de la Universidad de Alicante han recogido datos en la plataforma continental alicantina. El estudio de dichos datos fue postergado una y otra vez, hasta que aparecieron los primeros trabajos de Tent-Manclús et al. (2009) y de la Vara et al. (2011). Con motivo de mi ingreso en el Instituto Multidisciplinar para el Estudio del Medio “Ramón Margalef” (IMEM), me comprometí en el año 2010 a dar una conferencia sobre la plataforma continental alicantina enfocada a la evolución de la línea de costa la Comarca del Bajo Segura, desde el último máximo glaciar (últimos 18.000 años), integrando todas las fuentes de información a mi alcance (Fig. 1). El objetivo era realizar una serie de mapas de cómo había sido la posición de la línea de costa a intervalos de 100 años, desde la actualidad hacia atrás en el tiempo hasta el último máximo glaciar. Con una simple división se obtiene que, al menos, serían necesarios 180 mapas. El mayor problema de esta empresa no fue el número de mapas a realizar, al final fueron 164 (Fig. 2), sino la falta de información al sureste de la Isla de Tabarca. De las sucesivas campañas de geofísica sólo se habían obtenido tres perfiles sísmicos de dicha zona, por lo que no había suficiente información para saber si los ríos Vinalopó y Segura convergieron durante el último periodo glaciar. Así que la modelización abarca la zona en que se tiene información, esto es: los últimos 15.000 años desde que el nivel del mar se encontraba a 70 metros por debajo del nivel actual y subía. En futuras campañas espero completar la zona hasta alcanzar el borde de la plataforma continental.Este trabajo recoge parte de los resultados del proyecto de investigación BTE2009-07830 del MCIT y en una aportación del GRUPOS03/085 de la Generalitat Valenciana

Development and desiccation of the sinus ilicitanus (South Alicante) in the last 15,000 years

En este trabajo se describe el cambio de la línea de costa en la parte sur de la provincia de Alicante para los últimos 15.000 años. Se ha obtenido integrando datos de diferentes fuentes y especialmente de perfiles sísmicos de alta resolución marinos de la plataforma continental anexa. Se han distinguido 10 periodos. Comienza con la transgresión marina tras la última glaciación, le sigue la formación del sinus ilicitanus entre los años 4.000 y 3.000 AC, y finaliza con un lento proceso de desecación hasta la actualidad, reducido a las lagunas del Fondo y Salinas de Santa Pola.This paper describes the change of the coastline in the southern part of the province of Alicante for the last 15,000 years. It is obtained by integrating data from different sources and especially high-resolution seismic profiles of the nearby marine continental shelf. Ten periods have been distinguished ranging from the marine transgression after the last glaciation, following the development of the sinus ilicitanus between 4,000 and 3,000 BC, and finally it begins a slow drying process until today, when it is reduced to the lagoons of the Fondo and Salinas of Santa Pola.Este trabajo ha sido financiado por el proyecto CGL2009-07830/BTE del Ministerio de Ciencia e Innovación y el grupo GV04B-629 de la Generalitat Valenciana

Origin and evolutionary trends of the Neogene genera Amaurolithus and Nicklithus (calcareous nannofossils)

Sediment samples from Ocean Drilling Program (ODP) Sites 999 and 1237 in the Caribbean Sea and Eastern Pacific Ocean were studied to monitor the evolution of ceratoliths from 7.4 Ma to 6 Ma. Orthorhabdus rugosus shows high variability at the end of the Tortonian to the Early Messinian (7.35 Ma to 6.91 Ma), resulting in the Amaurolithus (7.354 Ma) and Nicklithus branches (6.985 Ma). Orthorhabdus rugosus is an ortholith with three blades (sinistral, median, and dextral). The first ceratholith, A. primus, has two arms and a horseshoe shape with marked laths, and is stable and concave upwards. Its sinistral arm is formed from the sinistral blade of O. rugosus and the right arm is formed from the other blades. Early robust A. primus evolved into stylised forms and then to A. delicatus (7.226 Ma), an almost plain horseshoe ceratolith with two arms. The left arm, usually the longer one, comes from the sinistral wing of A. primus and has a characteristic flattened omega section (Ω) without laths. There is a distribution overlap between A. primus and A. delicatus; the highest occurrence of the first one, at 6.282 Ma, is a newly proposed bioevent for the Messinian. After this, Amaurolithus does not have laths in its longer left arm and should be included in A. delicatus. The second branch has only one species, Nicklithus amplificus, which became extinct at 6.049 Ma. In addition, the dextral and median blades of O. rugosus form N. amplificus dextral arm and the sinistral arm, which has the characteristic beak, hook, or hawk's bill, which is the main difference between the development of this horseshoe and that of the previous one. The descriptions of A. primus, A. delicatus, and N. amplificus were specified based on the proposed evolutionary genesis.This work was supported by projects RTI2018-099489-B-I00 and PID2020-114381GB-I00 (Spanish Ministry of Science, Innovation and Universities). This study was funded by the European Union NextGenerationEU project GVA-THINKINAZUL/2021/039

Olistostromas originados por glaciares de sal al Sur de la Sierra del Cajar (cuenca neógena de Mula, Murcia)

Se describen unos glaciares de sal en la cuenca de Mula

Origin and evolution of the Neogene calcareous nannofossil Ceratolithus

Sediment samples of deep marine oceanic ODP boreholes from sites 999 in the Caribbean Sea and 1237 in the Eastern Pacific Ocean covering the period between 6 and 4.5 Ma have been studied with a focus on ceratolith evolution. Orthorhabdus rugosus is a nannolith with three blades (sinistral, median, and dextral) that first appeared during the Serravallian, it is not-birefringent in its stable orientation. It shows a high morphological variability time-interval at the end of the Messinian to the basal Pliocene (5.5 to 5 Ma) during which Ceratolithus (5.484 Ma) evolved. Changes occurred in the sinistral and median blades, whilst the dextral blade was reduced. Ceratolithus finifer n. comb is the first species of the evolutionary line. The nannolith stable position changed during its evolution, resulting in the older forms showing low birefringence and the younger ones moderate to high birefringence in the most stable orientation. Ceratolithus acutus, with an arrowhead shape, Ceratolithus armatus, and the morphologically distinct C. larrymayeri evolved from C. finifer with all three species showing high birefringence. The previous O. rugosus and C. finifer continued. Finally, C. armatus gives rise to C. cristatus. Ceratolithus atlanticus and C. tricorniculatus also evolved from C. finifer. All the species mentioned become extinct during the Pliocene except Ceratolithus cristatus that lives today. Detailed observations permit the analysis of the evolutionary trends of the group, possible mechanisms, patterns, and processes of speciation, and establish new criteria to define the species that, by their relative abundance and short geologic range, have permitted adjustment of biostratigraphic markers for this period.This work was supported by the projects RTI2018-099489-B-I00 and PID2020-114381GB-I00 (Spanish Ministry of Science, Innovation, and Universities). This study was funded by the European Union NextGenerationEU (PRTR-C17.I1) project GVA-THINKINAZUL/2021/039

Braquiópodos fósiles del Jurásico Inferior de la Sierra de Los Frailes (Alicante). Resultados preliminares

The revision of the fossil collection of Daniel Jiménez de Cisneros join with the re-study of his Early Jurassic quarries has allowed to obtain new collections of brachiopods, mainly of Sinemurian and Pliensbachian age. These collections contain, in addition to the classic species described, new species of species mentioned for the first time in the Early Jurassic of the Betic Range. In the present paper, an outcrop in the Sierra de los Frailes (London de las Nieves, Alicante), located in the front of a aggregate quarry which containing an abundant fauna of brachiopods is characterized. New studies, at the moment in course, will preview more diversity and greater abundance of this fauna, because of the result of new collections.Este trabajo ha sido realizado en el marco del proyecto BTE 2002-01113, del grupo de investigación GRUPOS03/085 (Generalitat Valenciana), y de la beca de Investigación COL-2102 de la Universidad de Alicante

3D geological model of the NW Bajo Segura Basin (Alicante, SE Spain)

Se ha realizado un modelo geológico en 3D de la porción NO de la Cuenca del Bajo Segura, por ser esta la que mostraba una menor complicación geológica. La cuenca se ha dividido en 7 sintemas (nombrados Ab,M1, M2, P1, P2, Pc y Q) y se ha utilizado como base de la cuenca el techo de la Formación Calizas de Las Ventanas (Ve). La construcción del modelo 3D permite un mejor conocimiento geológico de la cuenca. El modelo apunta a una mayor complicación tectónica de lo supuesto en un principio.It has been made a 3D geological model of the NW portion of the Bajo Segura Basin, as this is the one showed a more simple geology. The basin has been divided into 7 synthems (named Ab, M1, M2, P1, P2, Pc, and Q) and has been used as the bottom of the basin the top of the Las Ventanas Formation limestones (Ve). The construction of the 3D model allows a better understanding of the basin geology. The model suggests a much more complicated tectonic structure.Este trabajo ha sido financiado por el proyecto CGL2009-07830/BTE del Ministerio de Ciencia e Innovación y el grupo GV04B-629 de la Generalitat Valenciana

Brachiopod faunal exchange through an epioceanic-epicontinental transitional area from the Early Jurassic South Iberian platform system

The La Mola region (eastern External Betic Zone) can be regarded as one of the easternmost complete Jurassic successions of the Betic Cordillera in the Iberian Peninsula, but the paleogeographical setting of their outcrops remains widely discussed. Analysis of brachiopod assemblages from the Lower Jurassic improves the accuracy of previous paleogeographical data, enabling identification of a mainly epioceanic transitional area in which influences of epicontinental habitats are also detected. Assemblage 1, mainly with a Mediterranean affinity but also sharing several constituents with the African and Northeastern Iberian basins, typifies the Sinemurian–Pliensbachian transition. Assemblage 2, as a whole, shows a transitional character between epioceanic and epicontinental habitats; it is subdivided into two successive and interrelated sub-assemblages: Ass. 2a (Demonense–Tenuicostatum Zones) reveals a free connection with the epioceanic Subbetic area, whereas Ass. 2b (Uppermost Pliensbachian–Lower Toarcian) shows a closer relationship with epicontinental environments. Assemblage 3 (Uppermost Spinatum–basal Serpentinum Zones) is commonly recorded in the peri-Iberian epicontinental platform system integrated within the NW-European bioprovince, but it can also be regarded as a marginal assemblage that is widespread in the westernmost Tethyan margin prior to the Early Toarcian extinction event. Assemblage 2 constitutes a suitable index for assessing the paleobiogeographical affinity of the La Mola region, as Ass. 2a is progressively replaced by Ass. 2b, thus triggering the arrival of epicontinental taxa to the more intra-epioceanic Subbetic environments, inferring a possible connection through the La Mola transitional slope. Consequently, this region enabled a faunal mixing and exchange between both environments, and La Mola likely remained as an area that would facilitate migration and an effective dispersal seaway or, at least, did not constitute an ecological filter-barrier for brachiopods. Biostratigraphical data from brachiopods and ammonites are correlated for the first time in La Mola, refining and calibrating biochronostratigraphical gaps in the pre-Domerian deposits where biochronological markers are usually scarce, and around the Pliensbachian–Toarcian boundary, a crucial timespan in which the Early Toarcian extinction event took place.This research is a contribution to projects CGL2015-66604-R (MINECO/FEDER) and to Research Group VIGROB-167 (University of Alicante)

Rediscovery of the Moratalla amber (Murcia, Spain): a Cretaceous outcrop in the southernmost end of the peninsular amber strip

This study is a contribution of the Spanish Ministry of Economy and Competitiveness project CGL2011-23948/BTE

Early Jurassic brachiopods from northern Spain in the Jiménez de Cisneros collection

Se actualizan sistemáticamente las especies de braquiópodos del Jurásico Inferior procedentes de varias localidades del N y NE de España alojados en la colección Jiménez de Cisneros, refiriéndolas a contextos actualmente contrastados, dotándolas así de un conveniente marco lito- y cronoestratigráfico. Se encuentran representados especímenes de la Rama Castellana y Aragonesa de la Cordillera Ibérica, Asturias, Pirineos y la Cordillera costera Catalana. La actualización ha permitido identificar 18 especies distintas desde el Sinemuriense al Aaleniense basal, contextualizándolas y comparándolas paleobiogeográficamente con el conjunto de plataformas que ocupaban los paleomárgenes de la Subplaca Ibérica durante el Jurásico Inferior.Early Jurassic brachiopods from several localities in North and Northeast Spain housed in the Jiménez de Cisneros historical collection have been updated.These specimens have been referred to nowadays widely recognized geological settings in the Iberian Peninsula, thus providing a lithological and cronostratigraphical context. As a results of this updating, eighteen species were identified derived from the Castilian and Aragonese branches of the Iberian Range as well as Asturias, Pyrenees and the Coastal Catalan Range. These species are dated in the Sinemurian-earliest Aalenian timespan and they have been paleobiogeographically settled and compared within the platforms system existing in the Early Jurassic Iberian paleomargins.Este trabajo se ha realizado bajo el marco del grupo de investigación VIGROB-167 (Universidad Alicante) y de los proyectos CGL2011-25894 y CGL2011-23947 del MICINN