Physical properties of sediment core AND-2A

Whole-core measurements of Wet Bulk Density (WBD), compressional (P)-wave velocity (Vp), and Magnetic Susceptibility were measured at a sampling interval of 1 or 2 centimetres (cm) throughout the AND-2A drill core for initial core characterisation and on-site correlation with seismic modeling to predict target-reflector depth. Measurements were made using a GEOTEK (Multi-Sensor-Core-Logger MSCL). Density and velocity standards were measured together with core runs of 3-6 metres (m) (and occasionally up to 18 m) throughout the entire depth range to monitor data quality. Drift of the magnetic susceptibility sensor was also monitored and corrected where necessary. These physical properties show a large range of values, reflecting the different nature of the various lithologies including extremely high velocity and density values in individual clasts, and the effects of cementation on porosity. A downcore increase in WBD and Vp occurs in the upper 200 m, however, no systematic trend exists at greater depths although large fluctuations on a m-decimetre- (dm) scale occur. Magnetic susceptibility is generally low (<100 x 10-5 SI), however, four intervals of high (>600 x 10-5 SI) susceptibility occur at 560, 800, 980 and 1 080 mbsf, indicating a relatively greater contribution of volcanic-derived material to the core site in the lower half of the AND-2A core.

(Table T2) Integrated intensity (peak area) of matrix minerals of ODP Hole 173-1068A

Mass-wasting deposits characterize the Upper Jurassic(?) to Lower Cretaceous sedimentary record of the Iberia Abyssal Plain. These deposits include olistostromes at Site 897, olistostromes and/or possible rock-fall deposits at Site 899, a breccia succession at Site 1068, slumped and fractured deposits at Site 1069, and a breccia succession at Site 1070. Whereas the exact origin of these deposits is uncertain, the regional common occurrence of middle to upper Mesozoic mass-wasting deposits suggests that they record the early rifting evolution of the west Iberia margin. This data report presents both qualitative and semiquantitative results from XRD analyses of the breccia matrix at Site 1068. In this study the matrix is defined as the fine-grained particles (as viewed through a binocular microscope) plus cement. Results are based on analytical methods that aimed to isolate the desired matrix from larger clast contamination prior to XRD analyses. In addition, the breccia was sampled at a higher resolution than was conducted aboard ship, producing a more complete description of downcore matrix mineralogical changes. The data presented here may be used to (1) further justify the subunit designation of Unit IV made aboard ship, (2) help determine to what degree the matrix and the larger clasts (studied in thin section aboard ship; Shipboard Scientific Party, 1998, doi:10.2973/odp.proc.ir.173.106.1998) are compositionally distinct, (3) help identify the extent of hydrothermal fluid migration in the breccia, and (4) support the proposed shipboard hypothesis that the Site 1068 breccia succession resulted from multiple mass-wasting.

Macerals in surface sediments of the Laptev Sea (Arctic Ocean)

Surface sediments from the Laptev Sea and adjacent continental slope were studied for their composition of particulate organic matter (OM) by means of maceral analysis. The composition of macerals in sediments gives information about the environment, terrigenous supply from the hinterland, and marine OM. With reference to their biological sources, we distinguish between terrigenous and marine macerals. We found that the particulate OM in the surface sediments of the Laptev Sea is predominantly of terrigenous origin (mean: 78%). However, distinct variations exist when looking in detail. In the shelf area, sediments may contain up to 99% terrigenous OM. Freshwater algae occur directly north of the river mouths, reflecting the strong fluvial influence. Relatively high amounts of marine OM (20-40%) are restricted to the upper continental slope, the Vilkitsky Strait and west of the New Siberian Islands, explained by increased surface-water productivity due to increased fluvial nutrient supply, open-water conditions, and phytoplankton blooms at the ice-edge.