Search results for "Campanian"
showing 5 items of 5 documents
Stage boundaries, global stratigraphy, and the time scale: towards a simplification
2004
International audience; This paper examines four facets of stratigraphic terminology and usage considered faulty and proposes corrective measures. The four perfectible areas are: (1) The system of dual nomenclature requiring discrete terminologies for the superpositional and temporal aspects of rock units. (2) The premise that a GSSP establishes the base of a stage as being coincident with the top of the preceding stage rather than simply defining it as the boundary between stages. (3) The rejection of supplementary (auxiliary) sections that would broaden the knowledge of a GSSP and enlarge the area in which it is easily usable. (4) The current dual system of nomenclature for Precambrian an…
Notes on some Late Cretaceous goniasterid starfish (Echinodermata, Asteroidea) from Belgium and Germany
2021
Both partially articulated specimens and dissociated marginal ossicles form the basis for erection of two new species of Late Cretaceous goniasterids from the Mons and Liège-Limburg basins (Belgium) and the Hannover area (Germany). Chomataster breizh sp. nov., which recalls the type species, Chomataster acules Spencer, 1913, but differs in several respects, is based on a partial external mould of the marginal frame of disc and arms in flint (upper Campanian Spiennes Chalk Formation; Mons Basin), as well as on a more or less complete individual, preserving small, spherical spines and granules and encased in a flint nodule from the upper Maastrichtian Nekum Member (Maastricht Formation; Liège…
Changements climatiques et océanographiques au cours du Campanien – approche couplée minéralogie et géochimie
2018
The origin of the Late Cretaceous (~100 – 65 Ma) global cooling is not yet well understood. The evolution of sea surface and bottom temperatures shows an acceleration of the cooling during the Campanian stage (~84 Ma). The main goal of this study was to explore the processes driving this cooling, focusing on Campanian sediments from the Tethyan, Boreal and Atlantic realms.The clay mineralogical assemblages of several (hemi)pelagic sites, selected along a S-N transect, from 5° to 45°N, reveal an increase in continental weathering during the Campanian, expressed by enhanced kaolinite inputs. The detrital input related to the uplift of new continental areas seems to evolve from south to north.…
SEM–EDS ANALYSIS AS A RAPID TOOL FOR DISTINGUISHING CAMPANIAN A WARE AND SICILIAN IMITATIONS
2013
The aim of this work is to examine whether it is possible to find chemical markers that allow a distinction to be made between the imported black glossed ‘Campanian A’ and the Sicilian imitation (end of fourth to first century BC) of these productions by carrying out quantitative chemical microanalysis of the slip using the SEM–EDS technique. The efficiency of the proposed analytical method has been tested on a set of ceramic samples corresponding to Sicilian black gloss imitations whose ceramic body has already been characterized petrographically by thin-section microscopy and chemically by XRF. The analytical data point to Na2O as a suitable chemical marker to distinguish between original…
ANALYSIS OF THE SEXUAL VARIABILITY IN THE SHELL OF THE SPANISH UPPER CRETACEOUS TURTLE DORTOKA VASCONICA (PAN-PLEURODIRA, DORTOKIDAE)
2021
The present study characterizes the morphological variability related to the sexual dimorphism in the shells of the Spanish Upper Cretaceous turtle Dortoka vasconica . This study is based on the material from its type locality: Lano, Burgos. Two morphotypes were identified there based on the posterior plastral area as well as two for the anterior plastral lobe. However, a correlation with the previously indicated morphotypes could not be established due to the disarticulation of the specimens and the limited information available on the sexual dimorphism of Pleurodira. The morphological variability previously identified for Dortoka vasconica is analysed here through a quantitative approa…