Search results for "diagenesis."
showing 3 items of 113 documents
Fosildiagénesis del anélido Rotularia spirulaea (Lamarck, 1818) (Polychaeta, Serpulidae) en el Eoceno del dominio pirenaico occidental
2018
The presence of the fossil polychaete Rotularia spirulaea (Lamarck, 1818) in Eocene deposits (middle Lutecian – upper Bartonian and (?) Priabonian) belonging to the western Pyrenean Domain is verified. In this paper, a fossildiagenetic study has been carried out. Fossils from three areas, corresponding to diff erent depositional settings, have been analysed. In area 1, sediments of the Ardanatz Sandstone and Ilundain Marls formations [Pamplona Basin and adjoining areas (Navarre)], were sampled. Here, the specimens of R. spirulaea were not substantially affected by taphonomic reworking and the original microstructure of the carbonate tube is preserved. The test consists of a thick external …
Holocene Spatiotemporal Redox Variations in the Southern Baltic Sea
2021
Low oxygen conditions in the modern Baltic Sea are exacerbated by human activities; however, anoxic conditions also prevailed naturally over the Holocene. Few studies have characterized the specific paleoredox conditions (manganous, ferruginous, euxinic) and their frequency in southern Baltic sub-basins during these ancient events. Here, we apply a suite of isotope systems (Fe, Mo, S) and associated elemental proxies (e.g., Fe speciation, Mn) to specifically define water column redox regimes through the Baltic Holocene in a sill-proximal to sill-distal transect (Lille Belt, Bornholm Basin, Landsort Deep) using samples collected during the Integrated Ocean Drilling Program Expedition 347. At…
Mise en évidence d'un Sénonien gypseux sous la série phosphatée du bassin des Ouled Abdoun: un nouveau point de départ pour l'origine des zones déran…
2013
In the Ouled Abdoun sedimentary basin (Morocco), the phosphatic series is composed of regular interbedded phosphatic and marly limestone layers. Exploitation of the phosphate in some deposits in this basin collides frequently with problems bound to the existence, in the phosphatic series, of disturbed areas (sterile bodies) qualified as derangements by the mining engineers of the Office Cherifian Phosphate Group (OCP). Their presence in the phosphatic layers causes two kinds of problems: (1) since the whole phosphatic sequence is overlain by a Quaternary cover, we do not know their volume proportion in the phosphatic layers, and therefore the reserves estimations can be wrong (2) they are g…