Éditeur(s) : HAL CCSD Société géologique de France
Résumé : International audience
The present study proposes to estimate the influence of climate, eustatism and local tectonics on the sedimentation of a basin margin at the syn-rift to post-rift transition. For that, paleomagnetic measurements were performed on a marine marly-calcareous sedimentary succession ranging from Upper Oligocene to Lower Miocene and located on the northern margin of the Liguro-Provençal basin. The magnetostratigraphic record is correlated to the reference geomagnetic polarity scale [ATNTS04, Lourens et al. 2004] with the help of biostratigraphy based on calcareous nannofossils and planctonic foraminifers [Oudet et al., 2010]. The resulting age model shows that the 100 m-thick sedimentary succession covers a time span of 5 m.y. from the Late Chattian to the Early Burdigalian. Despite several exposure surfaces and a change in the sedimentation rate, no significant hiatus of sedimentation is documented. In addition, we also estimate the paleoenvironmental evolution through the sedimentary succession. Comparing the dated paleoenvironmental reconstruction with global {delta}18O and sea level curves [Miller et al., 2005], we show that the Carry-le-Rouet succession is an excellent paleoclimatic archive. Indeed, coral reefs developed at the glacial-interglacial stage transition marking the end of the Oligocene. In addition, the most diversified coral reefs occurred during the warmest period of the Aquitanian. During rifting, bathymetric variations recorded in the studied succession are related to local synsedimentary tectonics whereas, during oceanic crust accretion, global sea level changes influence the sedimentation. This result allows to characterise and to accurately date the break-up unconformity at 20.35 Ma.
EISSN: 1777-5817

hal-00619040
https://hal.archives-ouvertes.fr/hal-00619040
DOI : 10.2113/gssgfbull.182.1.37

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
The stratigraphy of the last deglaciation sequence is investigated in Lake Saint-Jean (Québec Province, Canada) based on 300 km of echo-sounder two dimensional seismic profiles. The sedimentary archive of this basin is documented from the Late Pleistocene Laurentidian ice-front recession to the present-day situation. Ten seismic units have been identified that reflect spatio-temporal variations in depositional processes characterizing different periods of the Saint-Jean basin evolution. During the postglacial marine flooding, a high deposition rate of mud settling, from proglacial glacimarine and then prodeltaic plumes in the Laflamme Gulf, produced an extensive, up to 50 m thick mud sheet draping the isostatically depressed marine basin floor. Subsequently, a closing of the water body due to glacio-isostatic rebound occurred at 8.5 cal. ka BP, drastically modifying the hydrodynamics. Hyperpycnal flows appeared because fresh lake water replaced dense marine water. River sediments were transferred towards the deeper part of the lake into river-related sediment drifts and confined lobes. The closing of the water body is also marked by the onset of a wind-driven internal circulation associating coastal hydrodynamics and bottom currents with sedimentary features including shoreface deposits, sediment drifts and a prograding shelf-type body. The fingerprints of a forced regression are well expressed by mouth-bar systems and by the shoreface-shelf system, the latter unexpected in such a lacustrine setting. In both cases, a regressive surface of lacustrine erosion (RSLE) has been identified, separating sandy mouth-bar from glaciomarine to prodeltaic muds, and sandy shoreface wedges from the heterolithic shelf-type body, respectively. The Lake Saint-Jean record is an example of a regressive succession driven by a glacio-isostatic rebound and showing the transition from late-glacial to post-glacial depositional systems.
ISSN: 0300-9483

hal-00984683
https://hal.archives-ouvertes.fr/hal-00984683
DOI : 10.1111/bor.12039

Éditeur(s) : Caught in the "fishing net" of information 14th Biennal EURASLIC Meeting 17-20 May, 2011, Lyon, France
Résumé : In addition to its promotion and conservation objectives, Archimer, Ifremer’s institutional repository, offers a wide range of bibliometric tools described in this document. As early as the recording stage, numerous automatic operations homogenize the information (author’s name, research body, department…), thus proving the quality of the bibliometric analyses. Now, Archimer enables, among others, the automatic calculation of several indicators defined by Ifremer and the different ministries in charge in the framework of its four-year contract. It also offers various criteria aimed at analysing its document production (eg. distribution of the value of the journals’ impact factors, evolution of the number of quotations in other publications, presentation of international collaborations…). As a consequence, the centralisation of Ifremer’s document production in Archimer will replace a number of different systems currently used by its research units to carry out such tasks. This should therefore result in an increase in Ifremer’s productivity as well as in a greater reliability of the archived documents.
En complément de ses objectifs de diffusion et de conservation, Archimer, l’archive institutionnelle de l’Ifremer, offre un ensemble d’outils bibliométriques. Dès l'enregistrement, de nombreux automatismes homogénéisent les informations (noms d'auteurs, organismes, affiliation interne...), gage de qualité des analyses bibliométriques. Archimer permet le calcul automatique de plusieurs indicateurs définis entre l'Ifremer et ses Ministères de Tutelles dans le cadre de son contrat quadriennal. Il offre également des éléments d’analyses de sa production documentaire (ex : répartition de la valeur des facteurs d’impacts des revues, évolution du nombre de citations des publications, présentation des collaborations internationales…). La centralisation de cette production documentaire dans Archimer permettra ainsi l’abandon d’une multitude de systèmes actuellement utilisés par les différentes unités de recherche pour assurer ces fonctions. C’est donc un gain de productivité autant que de fiabilité qui est attendu.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/00031/14253/11537.pdf
http://archimer.ifremer.fr/doc/00031/14253/11886.pdf
http://archimer.ifremer.fr/doc/00031/14253/