End-Cretaceous marine mass extinction not caused by productivity collapse

An asteroid impact at the end of the Cretaceous caused mass extinction, but extinction mechanisms are not well-understood. The collapse of sea surface to sea floor carbon isotope gradients has been interpreted as reflecting a global collapse of primary productivity (Strangelove Ocean) or export productivity (Living Ocean), which caused mass extinction higher in the marine food chain. Phytoplankton-dependent benthic foraminifera on the deep-sea floor, however, did not suffer significant extinction, suggesting that export productivity persisted at a level sufficient to support their populations. We compare benthic foraminiferal records with benthic and bulk stable carbon isotope records from the Pacific, Southeast Atlantic, and Southern Oceans. We conclude that end-Cretaceous decrease in export productivity was moderate, regional, and insufficient to explain marine mass extinction. A transient episode of surface ocean acidification may have been the main cause of extinction of calcifying plankton and ammonites, and recovery of productivity may have been as fast in the oceans as on land

HMAP Dataset 10: Catalonian Coast

Fish (various) landings and fishing effort in Catalonia, 1831-1984

Palaeoenvironmental turnover across the Cenomanian-Turonian transition in Oued Bahloul, Tunisia: Foraminifera and geochemical proxies

The integrated analysis of foraminiferal assemblages, geochemical proxies, and stable isotopes in the Oued Bahloul section (Tunisia) allowed us to reconstruct the environmental turnover across the Cenomanian–Turonian boundary. An increase in palaeoproductivity proxies (P/Ti, U/Al, Sr/Al) and in d13C values, and a decrease in foraminiferal diversity and d18O values mark the beginning of the Oceanic Anoxic Event 2 (OAE2) at the Rotalipora cushmani and Whiteinella archaeocretacea biozones boundary. Eutrophic conditions at the seafloor and in the water column are evidenced by high proportions of buliminids and the replacement of planktic oligotrophic specialist Rotalipora by eutrophic opportunist Hedbergella. The enrichment in organic matter and redox sensitive elements, together with the abundance of low-oxygen tolerant benthic foraminifera, indicate dysoxic conditions in the deep-water column and at the seafloor (higher Uaut than Moaut). Among planktic foraminifera, deep- and intermediate-dwellers disappear (Rotalipora and Globigerinelloides), and surface-dwellers proliferate (Hedbergella). The persistency of the poorly oxygenated conditions during the W. archaeocretacea Biozone locally produced euxinic conditions where MoEF and Moaut reach high values, diversity presents minimum values, and benthic foraminifera temporarily disappear. The maximum percentage of heterohelicids indicates a stratified water column with a well-developed oxygen minimum zone. Improved oxygen conditions returned in the upper part of the W. archaeocretacea Biozone and Helvetoglobotruncana helvetica Biozone, with a slow recovery of foraminiferal assemblages, decrease in eutrophic genera (Heterohelix) and increase in mesotrophic genera (Whiteinella). A gradual increase in d18O values suggests decreased temperatures in surface waters. The OAE2 has been attributed to global temperature changes and palaeoceanographic reorganization. The poor mixing of surface and deep waters and enhanced primary productivity related to global warming – associated with increasing continental weathering and nutrient runoff – may have favored the eutrophication of the ocean and the expansion of the oxygen minimum zone

Updating a Paleogene magnetobiochronological time scale through graphical integration

All studies focused on the evaluation of paleoecological variability over geological time must be linked to a specific age or time interval, which can be defined using different time scales (biostratigraphic, chronostratigraphic, geochronological or orbital). Therefore, integrated time scales are essential to allow comparisons of data from different locations and/or to assess evolutionary and other events through time. Here we use a new method to update a Paleogene magnetobiochronological time scale, with the following contributions: • The update of the Paleogene magnetobiochronological scale was made by graphical correlation with new age models and adding calcareous nannoplankton and planktonic foraminiferal biozones from different authors. • An excel file structure was proposed to plot any kind of data in MATLAB software, as long as they are associated with some of the scales shown in our updated version of Paleogene magnetobiochronology. • The excel file structure facilitates the analysis of long-term trends of taxonomic groups throughout the Paleogene, and of their evolution in a period characterized by intense climate variability

La sedimentación carbonatada en el Prepirineo aragonés durante el Cretácico superior

Carbonate facies analysis carried out in the Upper Cretaceous of the Aragonese Prepyrenees (South-Pyrenean Basin) allows us to establish the palaeogeographic and palaeoambiental reconstruction for this area. Three stages have been established in order to show the sedimentary evolution for the Upper Cretaceous. During the Stage 1 (Upper Santonian) the sedimentary domain was initially flooded. In the Stage 2 (lowermost Campanian- Upper Campanian) offshore bars developed at the western and eastern ends; the rest of the sedimentary basin consisted of a shallow carbonate platform whose bottom-floor was inhabited by rudists and benthic foraminifera. During the Stage 3 the generalized shallowing of the platform gave way, during the Maastrichtian, to the continental Garumn facies deposit.El análisis de las facies carbonatadas realizado en el Cretácico superior del Prepirineo aragonés ha permitido establecer la reconstrucción paleogeográfica y paleoambiental para este sector de la Cuenca Surpirenaica. Se han establecido tres estadios de evolución de la sedimentación para el Cretácico superior. Durante el Estadio 1 (Santoniense superior) tuvo lugar la inundación inicial de la cuenca de sedimentación; en el Estadio 2 (Campaniense basal-Campaniense superior) se desarrollaron barras costeras en los extremos oriental y occidental del área estudiada, mientras que el resto de la cuenca estaba ocupada por una plataforma carbonatada somera cuyos fondos fueron ampliamente colonizados por organismos bentónicos, principalmente rudistas y foraminíferos. En el Estadio 3 tuvo lugar una somerización generalizada de la plataforma, que durante el Maastrichtiense dio paso al depósito de los materiales continentales correspondientes a la facies Garumn

Turnover and stability in the deep sea: Benthic foraminifera as tracers of Paleogene global change

Benthic foraminifera are the most common meiofaunal unicellular deep-sea biota, forming skeletons used as proxies for past climate change. We aim to increase understanding of past non-analog oceans and ecosystems by evaluating deep-sea benthic foraminiferal responses to global environmental changes over latest Cretaceous through Oligocene times (67–23 million years ago). Earth suffered an asteroid impact at the end of the Cretaceous (~instantaneous; 66 Ma), episodes of rapid global warming during the Paleocene-Eocene Thermal Maximum (PETM; ~56 Ma) and other hyperthermals (millennial timescales), followed by gradual, but punctuated cooling (timescales of hundred thousands of years) from a world without polar ice sheets to a world with a large Antarctic ice sheet. Here we present the first compilation of quantitative data on deep-sea foraminifera at sites in all the world''s oceans, aiming to build a first unique, uniform database that allows comparison of deep-sea faunal turnover across the uppermost Cretaceous through Paleogene. We document variability in space and time of benthic foraminiferal diversity: lack of extinction at the asteroid impact even though other marine and terrestrial groups suffered mass extinction; major extinction at the PETM followed by recovery and diversification; and gradual but fundamental turnover during gradual cooling and increase in polar ice volume (possibly linked to changes in the oceanic carbon cycle). High latitude cooling from ~45 Ma on, i.e., after the end of the Early Eocene Climate Optimum (53.2–49.2 Ma), may have made the middle Eocene a critical period of several millions of years of faunal turnover and establishment of latitudinal diversity gradients. This compilation thus illuminates the penetration of global change at very different rates into the largest and one of the most stable habitats on Earth, the deep sea with its highly diverse biota

Experimentos de disolución de CaCO_3 en foraminíferos bentónicos aglutinados del Paleoceno-Eoceno en Zumaya (Cuenca Vasco-Cantábrica, España)

Durante el evento de calentamiento global conocido como Máximo Térmico del Paleoceno-Eoceno (PETM por sus siglas en inglés; hace ~55.8 Ma) tuvo lugar la mayor extinción de foraminíferos bentónicos de medios profundos de todo el Cenozoico. Mucho se ha especulado sobre las causas de dicha extinción, que incluyen cambios en la productividad y/o en la oxigenación de las aguas, cambios metabólicos y en la composición del aporte alimenticio al fondo marino, o la acidificación de los océanos relacionada con el aporte masivo de isótopos de carbono ligero al sistema océano-atmósfera, entre otros. En el presente estudio se analiza el potencial de la acidificación como agente desencadenante de las extinciones. En el corte de Zumaya (Cuenca Vasco-Cantábrica), el Eoceno inicial está marcado por un intervalo de 4 m con muy bajo contenido en CaCO3. Con el fin de analizar si la disolución del carbonato tuvo una incidencia directa sobre las extinciones del PETM, se han realizado experimentos de disolución en diversas especies de foraminíferos bentónicos aglutinados procedentes de Zumaya. En general, las especies aglutinadas que no desaparecen en el intervalo de máxima disolución en Zumaya son aquellas que fueron poco o nada afectadas por los experimentos de disolución, pues no presentan partículas y/o cemento calcáreo. No obstante, algunas especies que se extinguieron y/o desaparecieron localmente durante el Eoceno inicial, como Dorothia cylindracea, Spiroplectammina spectabilis y Haplophragmoides cf. walteri, resultaron ser resistentes a la disolución. Estos resultados sugieren que, además de la acidificación, debieron darse otros factores que contribuyeron a la desestabilización de las asociaciones de foraminíferos bentónicos

The era of nano-bionic: 2D materials for wearable and implantable body sensors

Nano-bionics have the potential of revolutionizing modern medicine. Among nano-bionic devices, body sensors allow to monitor in real-time the health of patients, to achieve personalized medicine, and even to restore or enhance human functions. The advent of two-dimensional (2D) materials is facilitating the manufacturing of miniaturized and ultrathin bioelectronics, that can be easily integrated in the human body. Their unique electronic properties allow to efficiently transduce physical and chemical stimuli into electric current. Their flexibility and nanometric thickness facilitate the adaption and adhesion to human body. The low opacity permits to obtain transparent devices. The good cellular adhesion and reduced cytotoxicity are advantageous for the integration of the devices in vivo. Herein we review the latest and more significant examples of 2D material-based sensors for health monitoring, describing their architectures, sensing mechanisms, advantages and, as well, the challenges and drawbacks that hampers their translation into commercial clinical devices

Paleoenvironmental Changes at ODP Site 702 (South Atlantic): Anatomy of the Middle Eocene Climatic Optimum

The Middle Eocene Climatic Optimum (MECO) was an unusual global warming event that interrupted the long-term Eocene cooling trend ca. 40 Ma. Here we present new high-resolution bulk and benthic isotope records from South Atlantic ODP Site 702 to characterize the MECO at a high latitude setting. The MECO event, including early and peak warming as well as recovery to background levels, had an estimated ~300 Kyr duration (~40.51 to ~40.21 Ma). Cross-plots (delta O-18 vs. delta C-13) suggest that the mechanisms driving coupled changes in O and C isotope values across the MECO were weaker or absent before the event. The paleoecological response has been evaluated by quantitative analysis of calcareous nannofossils and benthic foraminifera assemblages. We document a shift in the biogeographical distribution of warm and temperate calcareous nannoplankton taxa, which migrated toward higher latitudes due to increased temperatures during the MECO. Conversely, changes in the organic matter flux to the seafloor appear to have controlled benthic foraminifera dynamics at Site 702. Benthic phytodetritus exploiting taxa increased in abundance coinciding with a positive delta C-13 excursion, ~150 Kyr before the start of the delta O-18 negative excursion that marks the start of MECO warming. Our data suggest that paleoecological disturbance in the deep sea predates MECO delta O-18 excursion and that it was driven by changes in the type and/or amount of organic matter reaching the seafloor rather than by increased temperature