Icnología de vertebrados de las facies Buntsandstein de Mallorca

Se describen, por primera vez en Mallorca, hasta cinco tipos diferentes de icnitas y pistas de vertebrados continentales dentro de las facies cuarzoareniticas y limosas rojas de la facies Buntsandstein del Triásico inferio

Karst, acantilados y calas en el Migjorn de Menorca

[spa]La costa sur de la isla de Menorca se caracteriza por la presencia, de forma más o menos continua, de acantilados verticales cortados en los depósitos carbonatados que constituyen una plataforma atribuida al Mioceno superior. Los acantilados se encuentran interrumpidos en la zona litoral por una marcada incisión producida por los barrancos que drenan toda la plataforma miocena del sur de la isla y que, en su desembocadura al mar, dan lugar a las denominadas calas. La forma de éstas viene controlada no tan sólo por la fracturación, que a su vez controla la red de drenaje, sino que también por la contribución de los procesos kársticos que están directamente relacionados con la zona de mezcla de aguas en los acuíferos litorales. La acción de la dinámica marina y en especial la oscilación del nivel marino durante el Cuaternario también participan en la configuración de la morfología de la calas. Las paredes verticales y un fondo plano debido al relleno sedimentario de las zonas inundadas por el nivel del mar durante el Holoceno son otras de sus características básicas.[eng]A continuous cliffy coast built up by a carbonate platform developed in a reef environment during the Upper Miocene characterizes the southern region –Migjorn– of Menorca. This structural platform is dissected by a set of canyon-like creeks that when reach the coast result in narrow and cliffy bays known as “cala”. The cala morphology, as well as the fluvial network with a preferential N-S orientation–, is controlled mainly by fractures but also by the karstic processes that are dominant in the area. These processes are related with the mixing zone water interference in coastal aquifers. The marine action is also quite important, since sea-level oscillation during Quaternary, the shape and attributes of calas were modified, and the sedimentary infilling related with the Holocene inundation, resulted in a flat floor that contrasts with the cliffy sides of the calas

Las costas rocosas del Migjorn de Menorca: acantilados y calas

[spa]La zona meridional de Menorca (Migjorn) se caracteriza por ser una plataforma carbonatada desarrollada en un ambiente arrecifal durante el Mioceno superior. Está surcada por una serie de cursos torrenciales fuertemente encajados que en su desembocadura al mar dan lugar a una forma de bahía denominada “cala” que está delimitada por paredes de elevada pendiente. La fracturación y la diaclasación penetrativa que afecta a la alternancia de materiales calcareníticos y calcisiltiticos miocenos, junto con la distribución de éstos, es el principal factor que condiciona el trazado de los cursos fluviales, así como el desarrollo de los procesos de tipo kárstico asociados a la circulación preferencial y la formación de conductos. La interacción en la zona litoral de los procesos endokársticos, en los cuales la mezcla de aguas favorece los procesos de disolución, la actividad torrencial, así como la dinámica marina –teniendo presente la variabilidad glacio-eustàtica acontecida durante el Cuaternario– favorece el desarrollo y dinamismo del propio karst (i.e. colapso de cavidades, formación de dolinas, etc.) lo que se traduce, finalmente, en la configuración de la geoforma tan característica y compleja que es la cala.[eng]The southern region of Menorca –Migjorn– is built up by a carbonate platform developed in a reef environment during the Upper Miocene. This structural platform is dissected by a set of canyon-like creeks that when reach the coast result in narrow and cliffy bays known as “cala”. Joints and penetrative fractures that affect the Upper Miocene calcarenites and calcilutites rock outcroups exert the main control of the streams pathway and direction. Karst processes also play a critical contribution related to the preferential circulation and void formation. The interaction at the coast between marine and endokarstic processes –where mixing zone waters enhance rock solution–, between the fluvial processes and sea level (including sea level fluctuations during Quaternary times– enhance the dynamics and the development of karst (i.e. cave collapse, dolines formation, etc.) and this, finally, results in the configuration of a very representative rock coast macroform such as the “cala”

A new fulmarine petrel (Aves: Procellariiformes) from the upper miocene of the Western Mediterranean

A new sea bird, Pterodromoides minoricensis gen. et sp. nov., similar in size and proportions to species of the modern genus Pterodroma, is described from Late Miocene breccias situated on the north-west coast of Menorca. The cranial osteology is similar to that of fulmarine petrels, but the large orbitonasal opening and characters of the postcranial skeleton justify its classification as a separate genus. At least one other species of procellariid occurs in the accompanying fossil asemblage, suggesting that Late Tertiary ecological conditions favoured sea bird populations in this area of the Mediterranean.PB94-1175 and PB98-0132 and AMB96-0843Peer Reviewe

Icnología de vertebrados de las facies Buntsandstein de Mallorca

Se describen, por primera vez en Mallorca, hasta cinco tipos diferentes de icnitas y pistas de vertebrados continentales dentro de las facies cuarzoareniticas y limosas rojas de la facies Buntsandstein del Triásico inferio

On the origin of the North Pacific arcs

We present a new hypothesis that relates global plate tectonics to the formation of marginal basins, island arcs, spreading ridges and arc-shaped mountain belts around the North Pacific Ocean. According to our model, the ellipsoidal-shaped Paleogene basins of the South China Sea, Parece-Vela Basin, Shikoku Basin, Sea of Japan and the Sea of Okhotsk in addition to those of the North American Cordillera can be attributed to the change in plate convergence direction at 42 Ma between the Indoaustralian and Eurasian plates. The new direction of convergence was parallel to the eastern continental margin of Asia and resulted in widespread extension perpendicular to this margin and to the western margin of North America. Both margins form part of a circle parallel to the Indoaustralian-Eurasian direction of convergence

Noves dades sobre el poblament paleolític al massís del Garraf-Ordal

Des de l"any 2000, el Grup de Recerca del Quaternari (GRQ) del SERP de la Universitat de Barcelona ha estat fent tasques arqueològiques en un conjunt de jaciments de cronologia plistocena a les comarques del Baix Llobregat i del Garraf, en l"entorn geogràfic dominat pel massís del Garraf. La major part de les localitats que s"han investigat eren inèdites com a jaciments abans d"aquestes intervencions, motiu pel qual l"estudi que se n"està fent està omplint un important buit de coneixement en el registre de la prehistòria d"aquesta part del territori, especialment entorn a aspectes que fan referència al medi natural i al comportament dels primers grups humans

MAGY project: MAllorca hydroloGY over the last few centuries. Instrumental validation of speleothem archives

Geochemical analyses of speleothems and cave monitoring offer a complete framework for cave systems concerning hydrological changes and climate variability at very different timescales. In this regard, one critical target becomes the period when paleoclimatic records overlap with the directly measured instrumental records of climate. In order to improve the interpretation of speleothems as paleoclimatic records and therefore elucidate past climate changes in the western Mediterranean region, the MAGY project intent is the comparison of a new collection of speleothem records from Mallorca Island, which spans the last centuries, with precipitation and temperature data acquired in the weathering station from the Mallorca airport. This information is particularly critical on this island which is likely to face high hydrological stress under the current conditions of climate change. The implementation of this study requires high-resolution trace element profiles obtained by LA-ICP-MS to detect even seasonality variability in the speleothems and parallel well-resolved age models. The combination of U/Th dating, the 14C technique, and the confocal laser scanning microscopy technique, which allows annual layer counting, will provide solid chronologies. Preliminary results show that the Mg/Ca signal corresponds with the precipitation patterns recorded by regional instrumental records

Noves dades sobre el poblament paleolític al massís del Garraf-Ordal

Des de l"any 2000, el Grup de Recerca del Quaternari (GRQ) del SERP de la Universitat de Barcelona ha estat fent tasques arqueològiques en un conjunt de jaciments de cronologia plistocena a les comarques del Baix Llobregat i del Garraf, en l"entorn geogràfic dominat pel massís del Garraf. La major part de les localitats que s"han investigat eren inèdites com a jaciments abans d"aquestes intervencions, motiu pel qual l"estudi que se n"està fent està omplint un important buit de coneixement en el registre de la prehistòria d"aquesta part del territori, especialment entorn a aspectes que fan referència al medi natural i al comportament dels primers grups humans

Structural Control on the Presence and Character of Calas: Observations from Balearic Islands Limestone Rock Coast Macroforms

Calas are characteristic embayed rocky coastline landforms related to steep-sided drowned valleys that were deeply incised during low sea-level stages into carbonate plateaus. This paper studies the factors that control the presence and character of calas in three different islands of the Balearic Archipelago (Mallorca, Menorca and Formentera) by means of Digital Elevation Model (DEM) reconstructions, embayment and catchment morphometric analysis and through the compilation of fault and joint orientations. All islands exhibit emerged carbonate platforms (Upper Miocene in age) characterised by horizontal or very gently-dipping bedding. Two distinct patterns observed at all study sites are the absence or poor development of calas when carbonate plateaus exhibit strong coast-parallel structures and a greater variability of cala embayment size according to stream catchment size, lithology or their catchment distance from the coastline. Furthermore, the amount of stream incision, and consequently the characteristics of a cala at its mouth, depends on the proportion of impermeable rocks exposed in each drainage basin and on the density and spacing of fractures. Karst collapse, dolines and valley infilling associated with Quaternary sea-level oscillations are also important in determining the shape and size of calas