Nannofossil bioevents and biozones of ODP Holes 197-1203A and 197-1204A on Detroit Seamount

Calcareous nannofossils were studied in sedimentary successions recovered from two holes on the Detroit Seamount in the northwestern Pacific Ocean. Preservation of calcareous nannoflora assemblages varies from poor to good throughout the sediments recovered from both Holes 1203A and 1204A. Biostratigraphic investigation allowed the identification of 19 nannofossil zones in Hole 1203A and 7 in Hole 1204A. The sedimentary cover in Hole 1203A ranges from lower Eocene (Zone NP12) to upper Miocene (Zone NN9). The sedimentary interval investigated directly overlying the basalt recovered at Hole 1204A is late Campanian in age (Zones CC22-CC23), and the top of the section is middle Eocene (Zone NP15) in age. Major unconformities were observed in Hole 1204A between upper Campanian (Zones CC22-CC23) and lower Thanetian (Zone NP7) sediments and between upper Thanetian (Zone NP8) and upper Ypresian (Zone NP12) sediments.

Cretaceous stable isotopic record and sea surface temperture estimation for ODP Site 207-1259

The Turonian (93.5 to 89.3 million years ago) was one of the warmest periods of the Phanerozoic eon, with tropical sea surface temperatures over 35°C. High-amplitude sea-level changes and positive d18O excursions in marine limestones suggest that glaciation events may have punctuated this episode of extreme warmth. New d18O data from the tropical Atlantic show synchronous shifts ~91.2 million years ago for both the surface and deep ocean that are consistent with an approximately 200,000-year period of glaciation, with ice sheets of about half the size of the modern Antarctic ice cap. Even the prevailing supergreenhouse climate was not a barrier to the formation of large ice sheets, calling into question the common assumption that the poles were always ice-free during past periods of intense global warming.

De "quantofrenias" y "artefactos" o la "doxa" en el reino de la "episteme" : Uso y abusos de las escalas de estimaciones sumadas en la evaluación del desempeño docente en contextos de educación superior universitaria

Este trabajo presenta una reflexión metodológica relativa al uso de escalas de estimaciones sumadas o Likert en la evaluación del desempeño docente en el contexto universitario. Se presentan antecedentes en el marco de las prescripciones técnicas para este tipo de escalamientos, así como un conjunto de observaciones referidas a la pertinencia de su aplicación con fines evaluativos y a sus limitaciones en tanto herramienta para la generación de conocimiento. Se concluye que la escala de Likert puede ser utilizada en contexto evaluativos, atendiendo al conjunto de requerimientos ligados a su aplicación y tratamiento analítico-interpretativo, reconociendo los problemas insalvables que presenta, de manera de sopesar y relativizar la construcción del dato numeral. De este modo, se hace explícita la crítica al carácter "quantofrénico" y "artefactual" que acompaña su aplicación, y que contradictoriamente se inscribe en un discurso que sitúa la evaluación docente en el marco de políticas de calidad en educación superior

Stratigraphy of the Campanian-Maastrichtian boundary in ODP Hole 122-762C

An integrated framework of magnetostratigraphy, calcareous microfossil bio-events, cyclostratigraphy and d13C stratigraphy is established for the upper Campanian-Maastrichtian of ODP Hole 762C (Exmouth Plateau, Northwestern Australian margin). Bulk-carbonate d13C events and nannofossil bio-events have been recorded and plotted against magnetostratigraphy, and provided absolute ages using the results of the cyclostratigraphic study and the recent astronomical calibration of the Maastrichtian. Thirteen carbon-isotope events and 40 nannofossil bio-events are recognized and calibrated with cyclostratigraphy, as well as 14 previously published foraminifer events, thus constituting a solid basis for large-scale correlations. Results show that this site is characterized by a nearly continuous sedimentation from the upper Campanian to the K-Pg boundary, except for a 500 kyr gap in magnetochron C31n. Correlation of the age-calibrated d13C profile of ODP Hole 762C to the d13C profile of the Tercis les Bains section, Global Stratotype Section and Point of the Campanian-Maastrichtian boundary (CMB), allowed a precise recognition and dating of this stage boundary at 72.15 ± 0.05 Ma. This accounts for a total duration of 6.15 ± 0.05 Ma for the Maastrichtian stage. Correlation of the boundary level with northwest Germany shows that the CMB as defined at the GSSP is ~800 kyr younger than the CMB as defined by Belemnite zonation in the Boreal realm. ODP Hole 762C is the first section to bear at the same time an excellent recovery of sediments throughout the upper Campanian-Maastrichtian, a precise and well-defined magnetostratigraphy, a high-resolution record of carbon isotope events and calcareous plankton biostratigraphy, and a cyclostratigraphic study tied to the La2010a astronomical solution. This section is thus proposed as an excellent reference for the upper Campanian-Maastrichtian in the Indian Ocean.

Abundances and contents of major silicoflagellates from IODP Holes of Exp302

The silicoflagellate taxa obtained in IODP Expedition 302 (ACEX) were identified and counted in order to establish the silicoflagellate biostratigraphy in the central Arctic Ocean. These microfossils in the ACEX samples were preserved in the Lithology Units 1/6 and 2, which are dark silty clay and biosiliceous ooze, respectively. The silicoflagellate skeletons in the ACEX samples are assigned to 56 taxa. Seven taxa were described as new species, which were abundant in Lithology Unit 2. Comparison with several study cases outside the Eocene Arctic Ocean suggested that the silicoflagellate assemblages in ACEX were unique in Lithology Unit 2. The dominance of silicoflagellate taxa varied throughout the lithological section. Based on the cluster analysis by Morishita similarity index C(Lambda), the silicoflagellate assemblageswere divided into nine assemblage groups. The silicoflagellate datum event of the first occurrence of Corbisema hexacantha in the lower part of Lithology Unit 1/6 is regarded. Based on the datum events for silicoflagellate and palynomorphs, the assigned epoch of Lithology Units 1/6 and 2 is the middle Eocene.