0000000000291142
AUTHOR
Elise Chenot
Changements climatiques et océanographiques au cours du Campanien – approche couplée minéralogie et géochimie
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.…
Environmental and climatic controls of the clay mineralogy of Albian deposits in the Paris and Vocontian basins (France)
18 pages; International audience; High-resolution clay mineral analyses were performed on lower and middle Albian deposits from the Paris and Vocontian basins in order to specify the weathering conditions that prevailed at that time. The clay mineral assemblages are composed of small proportions of chlorite and vermiculitic clays associated with abundant illite, R0 type illite-smectite mixed-layers (smectite) and kaolinite. Clay minerals originated from the physical alteration and chemical weathering of rocks and soils outcropping on the Variscan massifs bordering the studied areas. In the Paris Basin, the covariation of illite and kaolinite suggests the reworking of these latter minerals f…
The formation of peak rings in large impact craters.
The Chicxulub impact crater, known for its link to the demise of the dinosaurs, also provides an opportunity to study rocks from a large impact structure. Large impact craters have “peak rings” that define a complex crater morphology. Morgan et al. looked at rocks from a drilling expedition through the peak rings of the Chicxulub impact crater (see the Perspective by Barton). The drill cores have features consistent with a model that postulates that a single over-heightened central peak collapsed into the multiple-peak-ring structure. The validity of this model has implications for far-ranging subjects, from how giant impacts alter the climate on Earth to the morphology of crater-dominated …
Extraordinary rocks from the peak ring of the Chicxulub impact crater: P-wave velocity, density, and porosity measurements from IODP/ICDP Expedition 364
Joint International Ocean Discovery Program and International Continental Scientific Drilling Program Expedition 364 drilled into the peak ring of the Chicxulub impact crater. We present P-wave velocity, density, and porosity measurements from Hole M0077A that reveal unusual physical properties of the peak-ring rocks. Across the boundary between post-impact sedimentary rock and suevite (impact melt-bearing breccia) we measure a sharp decrease in velocity and density, and an increase in porosity. Velocity, density, and porosity values for the suevite are 2900–3700 m/s, 2.06–2.37 g/cm3, and 20–35%, respectively. The thin (25 m) impact melt rock unit below the suevite has velocity measurements…