Late Neogene benthic foraminifera and stable carbon isotope record of the blake Outer Ridge

Carbon isotope and benthic foraminiferal data from Blake Outer Ridge, a sediment drift in the western North Atlantic (Ocean Drilling Program Sites 994 and 997, water depth ~ 2800 m), document variability in the relative volume of Southern Component (SCW) and Northern Component Waters (NCW) over the last 7 Ma. SCW was dominant before ~5.0 Ma, at ~3.6-2.4 Ma, and 1.2-0.8 Ma, whereas NCW dominated in the warm early Pliocene (5.0-3.6 Ma), and at 2.4-1.2 Ma. The relative volume of NCW and SCW fluctuated strongly over the last 0.8 Ma, with strong glacial-interglacial variability. The intensity of the Western Boundary Undercurrent was positively correlated to the relative volume of NCW. Values of Total Organic Carbon (TOC) were > 1.5% in sediments older than ~ 3.8 Ma, and not correlated to high primary productivity indicators, thus may reflect lateral transport of organic matter. TOC values decreased during the intensification of the Northern Hemisphere Glaciation (NHG, 3.8-1.8 Ma). Benthic foraminiferal assemblages underwent major changes when the sites were dominantly under SCW (3.6-2.4 and 1.2-0.8 Ma), coeval with the 'Last Global Extinction' of elongate, cylindrical deep-sea benthic foraminifera, which has been linked to cooling, increased ventilation and changes in the efficiency of the biological pump. These benthic foraminiferal turnovers were neither directly associated with changes in dominant bottom water mass nor with changes in productivity, but occurred during global cooling and increased ventilation of deep waters associated with the intensification of the NHG.

Consolidation characteristics of outer Bengal Fan deposits (Table 1)

The state of consolidation of outer Bengal Fan deposits is closely related to their depositional history. Early Pleistocene sediments are underconsolidated, i.e., fabric strength is lower than under equilibrium with the present overburden stress, at depths greater than 60-80 mbsf. This may be due to rapid accumulation (>15-20 cm/k.y.) and overlying low-permeability (<10**-7 cm/s) deposits. The underlying Pliocene sediments are overconsolidated, i.e., fabric strength is higher than in equilibrium with the present overburden stress; at Sites 717 and 719 the sediments are slightly overconsolidated, whereas at Site 718 the overconsolidation is significant. Overconsolidation is explained by erosion that occurred during the early Pleistocene for which a stratigraphic gap was recorded in the drilled cores. The eroded section is estimated to be in the range of 10-40 m at Sites 717 and 719, respectively, and 130-150 m at Site 718. Below 250-300 mbsf the most sediments are normally consolidated. The amount of erosion seems to be related to block rotation and uplift due to intraplate deformation.

(Table 1) Pollen analysis of peat horizons obtained from sediment cores of Beveroe-lagoon, Outer Flensburg Fjord

Pollen analytical studies were carried out on two sediment cores from Outer Flensburg Fjord taken by N. Exon (1972). 1) Based on the occurrence of Fagopyrum, the lower peat horizon (ca. 40 cm below mean sea level) of the inner lagoon near Beveroe developed after 1400 AD. The dominance of Pinus indicates that its formation may have taken place as late as the end of the 17th. Century. 2) Core No. 10872 from a water depth of 26.5 m contains the pollen zones VIII through the beginning of XI (Overbeck, 1950). Although salinity maxima fall in zone IX, they are not reflected in the pollen curves which show the normal picture found in South Jütland.

Can we delay a greenhouse warming? : the effectiveness and feasibility of options to slow a build-up of carbon dioxide in the atmosphere /

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The 1976 standard atmosphere above 86-km altitude : recommendations of Task Force II to COESA /

Bibliography: p. 68-70

Present state of knowledge of the upper atmosphere, 1990 : an assessment report : report to Congress /

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The atmosphere and the sun,

Publication 3062.

A singer in the outer court; a collection of songs and verses.

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On the necessity of cultivating water bacteria in an atmosphere saturated with moisture.

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A large-scale CO₂ observing plan : in situ oceans and atmosphere (LSCOP) /

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