Oligocene plaktonic foraminifera of the Indian Ocean ODP Leg 115 sites

We drilled 13 holes on Ocean Drilling Program Leg 115 in the Indian Ocean and recovered Paleogene sediments that consisted primarily of pelagic components. Planktonic foraminifer assemblages displayed high diversity throughout the Paleogene from the late Paleocene to the Oligocene/Miocene boundary and consist of predominantly warm-water species. Faunas of middle Eocene age are remarkably well represented. Biostratigraphic assignment was, however, very difficult because of the turbiditic character of most of the Paleogene sediments. Reworking is a constant feature of the middle Eocene through early Oligocene planktonic faunas, with reworked faunas frequently overwhelming the younger ones. Preservation within turbidites ranges from excellent to very poor to total destruction of planktonic foraminifers. A major dissolution episode is recorded in the interval that spans most of the late Eocene through the early Oligocene, especially at the deeper sites where the source area was probably well below the lysocline. Redeposition decreases markedly by the mid-Oligocene, but it is only by late Oligocene Zone P22 that normal sedimentation resumes and/or redeposition decreases even at the most affected sites (such as Hole 709C). Comparison with other sites drilled previously in the Indian Ocean reveals that mixed assemblages were already known for sediments from the Mascarene Plateau-Seychelles Bank and surrounding basins during that time span. Because of the disturbances that characterize Paleogene deposits, hiatuses are difficult to detect; nevertheless, a hiatus of less local importance, spanning Subzone P21b, was detected in three holes at different water depths.

Chemical composition of <0.001 mm grain size fraction from sedimentary rocks and bottom sediments of the Philippine Sea

Distriburtion and formation of clay minerals in different types of bottom sediments from the West Pacific are under consideration.

Grain size distributions of the Bossons glacier (France)

The study presented in this PhD memory aim at better define and quantify the present timeerosion processes in glacial and proglacial domain. The Glacier des Bossons, situated in theMont-Blanc massif (Haute-Savoie, France), is a good example of a natural and nonanthropizedsystem which allows us to study this topic. This glacier lies on two mainlithologies (the Mont-Blanc granite and the metamorphic bedrock) and this peculiarity is usedto determine the origin of the glacial sediments. The sediments were sampled at the glaciersurface and at the glacier sole and also in the subglacial streams in order to understand themechanisms of mechanical erosion and particle transportation in glacial domain. The study ofthe granulometric distribution and the origin of the sediments were performed by a lithologicanalysis at macro-scale (naked-eye) and a geochemical analysis at micro-scale (U-Pb datingof zircons). These analyses allowed specifying the characteristics of glacial erosion andtransport. (1) the supraglacial sediments derived from the erosion of the rocky valley sides aremainly coarse and the glacial transport does not mix these clasts with those derived from thesub-glacial erosion, except in the lower tongue; (2) the sub-glacial erosion rates areinhomogeneous, erosion under the temperate glacier (0.4-0.8 mm/yr) is at least sixteen timesmore efficient than the erosion under the cold glacier (0.025-0.05 mm/yr); (3) the sub-glacialsediments contain a silty and sandy fraction, resulting from processes of abrasion andcrushing, which is evacuated by sub-glacial streams. The high-resolution temporal acquisitionof hydro-sedimentary data during the 2010 melt season, between the May 5th and theSeptember 17th, allowed defining the seasonal behavior of the hydrologic and sedimentaryfluxes. The sediment exportation occurs mainly during the melt season therefore, quantify thesediment fluxes in the Bossons stream and measure regularly the topographic evolution of thefluvio-glacial system allows to perform a sedimentary balance of the erosion of glacial andnon-glacial domains. During the year 2010, about 3000 tons of sediments were eroded with430 tons settled on the fluvio-glacial system. By analyzing the evolution of suspendedparticulate matter concentrations in the Bossons stream upstream and downstream the fluvioglacialsystem, the part of glacial erosion and non-glacial denudation in the sedimentarybalance could be proportioned. The erosion during the stormy events of the uncoveredmoraines, confining the fluvio-glacial system of the Bossons stream, furnishes at least 59% ofthe sediments exported by the Bossons stream and glacial erosion (41% of the flux) istherefore less efficient comparatively. The long-term evolution of the glacial systems inperiod of global warming would show a sustained erosion of proglacial environments(mountain sides and moraines) recently exposed and therefore an increasing of the detritalfluxes. The Glacier des Bossons protects the summit of the Mont-Blanc, the differentialerosion between zones under the ice and non-glacial could lead to an increase of thedifference of altitude between valleys and summits.

Grain size composition of 275 sediment profiles from the Arctic seas

This data set contains grain size analyses of bottom sediments collected by scientists from the V.P. Zenkovich Laboratory of Shelf and Sea Coasts (P.P. Shirshov Institute of Oceanology, Russian Academy of Sciences) during the Project ''Arctic Shelf of the Eurasia in the Late Quaternary'' in a number of expeditions to the Barents, Kara, East Siberian and Chukchi Seas on board the research vessels R/V Professor Shtokman, H/V Dmitry Laptev, H/V Malygin, and icebreaker Georgy Sedov since 1978. The analyses have been carried out according to the methods published by Petelin (1967) in the Analytical Laboratory of the P.P. Shirshov Institute of Oceanology. Archiving and electronic publication was performed through a data rescue by Evgeny Gurvich in 2003.