Variaciones espaciales y temporales del registro del límite K/T en Haiti: implicaciones acerca del evento o eventos

El registro en la capa del límite K/T (KTB), en diferentes localidades de la Península Meridional de Haití, muestra claras evidencias de disrupciones físicas causadas por el impacto postulado de un bólico al final del Maastrichtiense. Tanto el registro bioestratigráfico como el litológico de la capa KTB, en diferentes localidades, muestra también diversos grados de mezcla, con componentes faunísticos de edades congruentes con los bioeventos característicos de la transición del límite, equivalentes a la parte terminal de la Zona de Abathomphalus mayaroensis y partes de las Zonas de Guembelitria cretacea y de Parvularugoglobigerina eugubina. La nanoflora calcárea también muestra taxones de la transición, concurrentes con los datos de foraminíferos, e indicativos de las Subzonas de Micula murus y Micula prinsii, así como de la Subzona de Cruciplacolithus primus (CP1a), del Paleoceno basal. La capa del límite tiene variaciones en su potencia, con un máximo de 75cm en el estratotipo de la Formación Beloc, y a techo de la capa principal tectítica hay un máximo de iridio. Los análisis geoquímicos y la datación radiométrica han demostrado también que las esférulas son tectitas (Premo e Izett, 1991) que pueden estar relacionadas cronológicamente con el evento de impacto registrado en Chicxulub, Yucatán, México, hace 65 Ma. Aún más, las delicadas estructuras sedimentarias primarias en la capa del límite son constantes en todos los afloramientos, aunque hay diferencias espaciales incluso a corta distancia. Además, en las áreas adyacentes al estratotipo (Platon Piton y Madame Toussaint) se encuentra una capa volcanogénica, bajo el nivel tectítico principal relacionado con el evento de Chicxulub, que muestra una laminación cruzada, tanto conspicua como críptica, indicativa de procesos de flujo complejos, multifásicos y subacuáticos que afectaron a la sedimentación de forma parecida a la del lecho KTB. Se conocen tales estructuras como características de la acción de ondas oscilantes sobre la cohesión de los sedimentos. El movimiento de las aguas asociado con un seiche es el único análogo actual conocido de un flujo subacuático que proporcione un mecanismo plausible para explicar el que varios niveles de la columna de agua, en una gran cuenca, pueden oscilar para desarrollar las estructuras observadas. Dada la magnitud del impacto del bólido, debieron desarrollarse ‘megaseiches’ en los océanos a escala mundial y, subsecuéntemente, se producirían otros ‘megaseiches’ más localizados durante los reajustes principales de la corteza. Esos fenómenos pueden así explicar la heterogeneidad de pautas y discrepancias faunísticas observadas en varias localidades del KTB, de distinta profundidad de depósito, en el mundo. Las estructuras representan un registro de los movimientos del agua y de la resuspensión de los sedimentos en momentos diferentes. Tal como se ha observado en seiches modernos a pequeña escala, la duración y atenuación de los movimientos del agua y la magnitud de la tracción y resuspensión estuvieron controlados por diversos modos oscilatorios que dieron lugar a complejas estructuras sedimentarias y al retrabajamiento de los microfósiles

Foraminiferal and calcareous nannoplankton biostratigraphy of the upper Badenian–lower Sarmatian strata in the SE Polish Carpathian Foredeep

The Badenian/Sarmatian boundary in the Central Paratethys has been traditionally identified by the faunal turnover recording an important environmental change possibly controlled by the change from marine to brackish conditions. The strata below the Badenian/Sarmatian boundary in the northern Carpathian Foredeep are included into the Pecten beds, and those above it into the Syndesmya beds. Foraminiferal study of the Babczyn 2 borehole which is one of the crucial sections in the northern Carpathian Foredeep, well-known for the depositional age of rhyolite tuff within the Pecten beds dated by Śliwiński et al. (2012) at 13.06 ±0.11 Ma, indicated that in fact the boundary occurs within the Syndesmya beds. This conclusion is based upon the rapid change from a stenohaline foraminiferal fauna to a euryhaline one, and the appearance of the species Anomalinoides dividens, the taxon regarded as the marker for the Sarmatian. In the Babczyn 2 and Cieszanów 1 (located ~2.5 km basinward of Babczyn 2) boreholes, Anomalinoides dividens appears 3.1–3.8 m above the replacement of stenohaline by euryhaline foraminifers. The calcareous nannoplankton study shows that the upper Badenian and the lower Sarmatian strata in the studied sections represent the NN6, undivided NN6-NN7, and NN7 zones

Planktonic Foraminiferal Biostratigraphy of the Upper Cretaceous of the Central European Basin

Planktonic foraminifera are one of the most stratigraphically important groups of organisms for the Cretaceous system. However, standard foraminiferal zonations based mostly on species from the Tethyan bioprovince are hardly applicable in temperate regions where warm-water taxa are scarce or lacking. We propose a foraminiferal zonation based on foraminiferal events recognized in the northern Foraminiferal Transitional Bioprovince, which likely has a high correlation potential at least at a regional scale. Fifteen planktonic foraminiferal zones are distinguished from the upper Albian up to the uppermost Maastrichtian strata in extra-Carpathian Poland and western Ukraine. From the bottom to the top, Thalmanninella appenninica, Th. globotruncanoides, Th. reicheli, Rotalipora cushmani, Whiteinella archaeocretacea, Helvetoglobotruncana helvetica, Marginotruncana coronata, M. sinuosa, Pseudotextularia nuttalli, Globotruncana linneiana, G. arca, Contusotruncana plummerae, Rugoglobigerina pennyi, Globotruncanella petaloidea and Guembelitria cretacea. These zones are calibrated by macrofaunal zonations

Planktonic Foraminiferal Biostratigraphy of the Upper Cretaceous of the Central European Basin

Planktonic foraminifera are one of the most stratigraphically important groups of organisms for the Cretaceous system. However, standard foraminiferal zonations based mostly on species from the Tethyan bioprovince are hardly applicable in temperate regions where warm-water taxa are scarce or lacking. We propose a foraminiferal zonation based on foraminiferal events recognized in the northern Foraminiferal Transitional Bioprovince, which likely has a high correlation potential at least at a regional scale. Fifteen planktonic foraminiferal zones are distinguished from the upper Albian up to the uppermost Maastrichtian strata in extra-Carpathian Poland and western Ukraine. From the bottom to the top, Thalmanninella appenninica, Th. globotruncanoides, Th. reicheli, Rotalipora cushmani, Whiteinella archaeocretacea, Helvetoglobotruncana helvetica, Marginotruncana coronata, M. sinuosa, Pseudotextularia nuttalli, Globotruncana linneiana, G. arca, Contusotruncana plummerae, Rugoglobigerina pennyi, Globotruncanella petaloidea and Guembelitria cretacea. These zones are calibrated by macrofaunal zonations

Late Maastrichtian cephalopods, dinoflagellate cysts and foraminifera from the Cretaceous-Paleogene succession at Lechowka, southeast Poland: Stratigraphic and environmental implications

© 2015 Elsevier Ltd. The Lechówka section comprises the most complete Cretaceous-Paleogene (K-Pg) boundary succession in Poland and is among 29 sites worldwide with the youngest ammonite record. Here, cephalopods (ammonites and nautilids), organic-walled dinoflagellates (dinocysts) and foraminifera from the uppermost Maastrichtian interval are studied. In terms of ammonite biostratigraphy, the upper Maastrichtian Hoploscaphites constrictus crassus Zone is documented up to a level 120 cm below the K-Pg boundary. There is no direct, ammonite-based evidence of the highest Maastrichtian H. constrictus johnjagti Zone. However, the predominance of the dinocyst marker taxon Palynodinium grallator suggests the presence of the equivalent of the uppermost Maastrichtian Thalassiphora pelagica Subzone, which is correlatable with the H. c. johnjagti ammonite Zone. The planktonic foraminiferal assemblage is coeval with that from the H. c. johnjagti Zone as well. These data indicate that the top of the Maastrichtian at Lechówka is complete within the limits of biostratigraphic resolution, albeit slightly condensed. The dinocyst and foraminiferal assemblages are dominated by taxa that are characteristic of high-energy, marginal marine environments. A reduction in test size among the calcareous epifaunal benthic foraminifera is observed at a level 50 cm below the K-Pg boundary, which is possibly related to environmental stress associated with Deccan volcanism.publisher: Elsevier articletitle: Late Maastrichtian cephalopods, dinoflagellate cysts and foraminifera from the Cretaceous–Paleogene succession at Lechówka, southeast Poland: Stratigraphic and environmental implications journaltitle: Cretaceous Research articlelink: http://dx.doi.org/10.1016/j.cretres.2015.08.012 content_type: article copyright: Copyright © 2015 Elsevier Ltd. All rights reserved.status: publishe

Late Maastrichtian cephalopods, dinoflagellate cysts and foraminifera from the Cretaceous-Paleogene succession at Lechówka, southeast Poland : Stratigraphic and environmental implications

The Lechówka section comprises the most complete Cretaceous-Paleogene (K-Pg) boundary succession in Poland and is among 29 sites worldwide with the youngest ammonite record. Here, cephalopods (ammonites and nautilids), organic-walled dinoflagellates (dinocysts) and foraminifera from the uppermost Maastrichtian interval are studied. In terms of ammonite biostratigraphy, the upper Maastrichtian Hoploscaphites constrictus crassus Zone is documented up to a level 120 cm below the K-Pg boundary. There is no direct, ammonite-based evidence of the highest Maastrichtian H. constrictus johnjagti Zone. However, the predominance of the dinocyst marker taxon Palynodinium grallator suggests the presence of the equivalent of the uppermost Maastrichtian Thalassiphora pelagica Subzone, which is correlatable with the H. c. johnjagti ammonite Zone. The planktonic foraminiferal assemblage is coeval with that from the H. c. johnjagti Zone as well. These data indicate that the top of the Maastrichtian at Lechówka is complete within the limits of biostratigraphic resolution, albeit slightly condensed. The dinocyst and foraminiferal assemblages are dominated by taxa that are characteristic of high-energy, marginal marine environments. A reduction in test size among the calcareous epifaunal benthic foraminifera is observed at a level 50 cm below the K-Pg boundary, which is possibly related to environmental stress associated with Deccan volcanism

Late Maastrichtian cephalopods, dinoflagellate cysts and foraminifera from the Cretaceous-Paleogene succession at Lechówka, southeast Poland : Stratigraphic and environmental implications

The Lechówka section comprises the most complete Cretaceous-Paleogene (K-Pg) boundary succession in Poland and is among 29 sites worldwide with the youngest ammonite record. Here, cephalopods (ammonites and nautilids), organic-walled dinoflagellates (dinocysts) and foraminifera from the uppermost Maastrichtian interval are studied. In terms of ammonite biostratigraphy, the upper Maastrichtian Hoploscaphites constrictus crassus Zone is documented up to a level 120 cm below the K-Pg boundary. There is no direct, ammonite-based evidence of the highest Maastrichtian H. constrictus johnjagti Zone. However, the predominance of the dinocyst marker taxon Palynodinium grallator suggests the presence of the equivalent of the uppermost Maastrichtian Thalassiphora pelagica Subzone, which is correlatable with the H. c. johnjagti ammonite Zone. The planktonic foraminiferal assemblage is coeval with that from the H. c. johnjagti Zone as well. These data indicate that the top of the Maastrichtian at Lechówka is complete within the limits of biostratigraphic resolution, albeit slightly condensed. The dinocyst and foraminiferal assemblages are dominated by taxa that are characteristic of high-energy, marginal marine environments. A reduction in test size among the calcareous epifaunal benthic foraminifera is observed at a level 50 cm below the K-Pg boundary, which is possibly related to environmental stress associated with Deccan volcanism

Cryogenic separation of glauconite and foraminifera from Cretaceous/Paleogene boundary in Nasiłów, Poland, for radiometric dating and stratigraphy

We have demonstrated that cryogenic separation of glauconite and foraminifera from the host rock allows to preserve the integrity of extracted specimens, assures minimal damage and causes no artificial fractionation. The K/Ar dating of two glauconite samples from Cretaceous/Paleogene boundary in the Nasiłów outcrop yields 62.0 and 66.3 Ma. The discrepancy in these dates, much larger than expected from analytical precision, may result from too low %K, which was 5.91 and 5.73, respectively