Search results for "stratigraphy"

Un nouveau modèle d'âge pour l'Autunien du bassin d'Autun à partir de datations U-Pb sur des tonsteins

2021

National audience; Le bassin d’Autun, bassin historique français stéphano-permien connu pour ses huiles de schistes et ses fossiles de plantes et vertébrés terrestres, a permis de définir le stratotype Autunien au 19ème siècle, référence pour les « étages » continentaux du Permien d’Europe. Pendant très longtemps, les âges du bassin et du stratotype Autunien ont reposé sur les biozonations établies par les microflores et macroflores, plus récemment à partir des faunes d’insectes, de crustacés et d’amphibiens (Schneider et al., 2020). L’équivalence d’âge en étages marins reposait sur des corrélations complexes à partir d’environnements mixtes marins et continentaux permettant d’utiliser, ent…

2016

Abstract. To date, very little is known about the distribution of natural gas hydrates in sedimentary matrices and its influence on the seismic properties of the host rock, in particular at low hydrate concentration. Digital rock physics offers a unique approach to this issue yet requires good quality, high-resolution 3-D representations for the accurate modeling of petrophysical and transport properties. Although such models are readily available via in situ synchrotron radiation X-ray tomography, the analysis of such data asks for complex workflows and high computational power to maintain valuable results. Here, we present a best-practice procedure complementing data from Chaouachi et al.…

In situ Laser Induced Breakdown Spectroscopy as a tool to discriminate volcanic rocks and magmatic series, Iceland.

2015

7 pages; International audience; This study evaluates the potentialities of a lab-made pLIBS (portable Laser-Induced Breakdown Spectroscopy) to sort volcanic rocks belonging to various magmatic series. An in-situ chemical analysis of 19 atomic lines, including Al, Ba, Ca, Cr, Cu, Fe, Mg, Mn, Na, Si, Sr and Ti, from 21 sampled rocks was performed during a field exploration in Iceland. Iceland was chosen both for the various typologies of volcanic rocks and the rugged conditions in the field in order to test the sturdiness of the pLIPS. Elemental compositions were also measured using laboratory ICP-AES measurements on the same samples. Based on these latter results, which can be used to ident…

Tracing tsunami signatures of thead551 andad1303 tsunamis at the Gulf of Kyparissia (Peloponnese, Greece) using direct pushin situsensing techniques …

2020

Paleoceanographic and paleoenvironmental changes in the Red Sea during the Messinian/Zanclean: new data from Site 225.

2013

Stratigraphical ranges of tegulated inoceramid bivalves in the type area of the Maastrichtian Stage (Belgium, the Netherlands)

2018

Abstract Recently collected material, in fine- to medium-grained biocalcarenites and in coeval flint nodules, of the tegulated inoceramid taxa Spyridoceramus tegulatus (von Hagenow, 1842) and Tenuipteria argentea (Conrad, 1858) from various members of the Gulpen Formation and the overlying Maastricht Formation allows their stratigraphical ranges to be refined. It is concluded that the ranges correspond closely to those in east-central Poland (Vistula [Wisla] River valley region), where S. tegulatus occurs in the lower Maastrichtian and lower upper Maastrichtian ( Endocostea typica , Trochoceramus radiosus and ‘ Inoceramus ’ ianjonaensis inoceramid zones, or Belemnella occidentalis and Belem…

The Burdigalian GSSP: the missing tile to complete the Neogene interval of the Geological Time Scale

2014

Resumen cronoestratigráfico de las rocas ígneas de Costa Rica basado en dataciones radiométricas

1992

Resume El presente trabajo recopila los resultados de aproximadamente 160 dataciones radiometricas K-Ar y U-Th que se han realizado en Costa Rica en los ultimos 20 anos. Con base en estas dataciones y en relaciones estratigraficas se establecio un cuadro cronoestratigrafico sobre la evolucion del magmatismo desde el Mesozoico hasta el presente. Las rocas igneas del Jurasico hasta el Oligoceno se caracterizan por su tendencia toleitica. A partir del Mioceno tardio predominan rocas de la serie calcoalcalina y la actividad volcanica culmina en el Pleistoceno con la erupcion de grandes volumenes de ignimbritas en la parte norte y central de Costa Rica y la edificacion de los estratovolcanes de …

The Mammalian successions of Sicily and Sardinia: a tentative of correlation with the biochronological frame of the Italian peninsula

2009

230Th/U-dating of carbonate deposits from ancient aqueducts

2016

Abstract Carbonate deposits in aqueducts, known as calcareous sinter, can reach a considerable thickness and are commonly annually laminated. Environmental and palaeoclimate proxies measured in calcareous sinter samples, such as stable oxygen and carbon isotopes and trace elements, can provide important high-resolution information on hydrological conditions, temperature, and local precipitation in the catchment area of an aqueduct. In order to utilize the proxy data for palaeoclimate reconstruction, the sinter deposits must be dated by annual laminae counting and more precisely by 230 Th/U-dating. The major problem of 230 Th/U-dating of calcareous sinter in aqueducts is the relatively large…