(Table 1) Average aluminium accumulation rate at 40 DSDP Sites for the time interval 0-10 Ma and relative rates for other time intervals

A six-fold increase in the rate of accumulation of Al in north and central Atlantic and Pacific Ocean sediments indicates vastly increased denudation of the continents during the past 15 Ma. The increase is more apparent in hemipelagic than pelagic sites, demonstrating widely distributed local controls. Similarities in the rate of increase in the Atlantic and Pacific show that tectonic elevation is not responsible for the difference in sedimentation rate. Also, similarities in the difference at sites of low and high latitude suggest that glaciation is not the most significant source. A lack of correspondence between sedimentation rates and Vail's sea-level curve similarly rule out that effect. The conclusion drawn here is that worldwide climatic deterioration during the late Tertiary is the explanation for the striking increase in detrital sedimentation in the World ocean.

(Table T1) Calcium carbonate mineralogy and stable isotopic composition of ODP Hole 182-1132C sediments

Petrographic observation and carbonate mineralogic and stable isotopic investigation were conducted on lower Oligocene to middle Miocene sediments recovered during Ocean Drilling Program Leg 182 from Site 1132, located at a water depth of 218.5 m immediately seaward of the shelf-slope break of the eastern Eyre Terrace in the western Great Australian Bight. The middle Miocene section consists of bioclastic packstone and grainstone with an interval of partially silicified nannofossil-foraminiferal chalk and is slightly to densely dolomitized. By contrast, the lower Oligocene to lower Miocene section is characterized by a predominance of planktonic and benthic foraminifers, high porosity, absence of chert, and weak dolomitization. The carbon and oxygen isotopic composition of calcites and dolomites between two sections, however, shows no significant difference.

(Table 1) Petrological description and consolidation properties of ODP Site 186-1150 and Hole 186-1151A

In order to determine the shear parameters of the forearc sedimentary strata drilled during Ocean Drilling Program Leg 186, West Pacific Seismic Network, Japan Trench, eight whole-round samples were selected from different depths in the drilled sections of Sites 1150 and 1151. Whereas Site 1150 lays above the seismically active part of the subduction zone, Site 1151 is situated in an aseismic zone. The aim of the triaxial tests was, apart from determination of the static stress strain behavior of the sediments, to test the hypothesis that the static stress strain parameter could differ for each sites. In order to simulate undrained deformation conditions according to the high clay mineral content of the strata, consolidated undrained shear tests were performed in a triaxial testing setup. Measurements of water content, grain density, organic content, and microtextural investigations under the scanning electron microscope (SEM) accompanied the compression experiments. After the saturation and consolidation stages were completed, failure occurred in the compression stage of the experiments at peak strengths of 280-7278 kPa. The stiffness moduli calculated for each sample from differential stress vs. strain curves show a linear relationship with depth and range between 181 and 5827 kPa. Under the SEM, the artificial fault planes of the tested specimen only show partial alignment of clay minerals because of the high content of microfossils.

Trace element abundance, and Sr and Nd isotope ratios of dust samples in the Pacific Ocean (Table 2)

Eolian dust preserved in deep-sea sediment cores provides a valuable indicator of past atmospheric circulation and continental paleoclimate. In order to identify the provenance of eolian dust, Nd and Sr isotopic compositions and Rb, Sr and rare earth element (REE) concentrations have been determined for the silicate fractions of deep-sea sediments from the north and central Pacific Ocean. Different regions of the Pacific Ocean are characterized by distinct air-borne inputs, producing a large range in epsolin-Nd (-10 to +1), 87Sr/86Sr (0.705-0.721), La/Yb (5-15), EuN/EuN* (0.6-1.0) and Sr/Nd (4-33). The average Nd isotopic composition of Pacific deep-sea sediments (epsilon-Nd = -6), is more radiogenic than the average from the Atlantic (epsilon-Nd = -8). In contrast, the average147Sm/144Nd ratio for Pacific sediments (0.114) is identical to that of Atlantic sediments and to that of global average riverine suspended material. The values of epsilon-Nd and147Sm/144Nd are positively correlated for the Pacific samples but negatively correlated for Atlantic samples, reflecting a fundamental difference between the dominant components in the end members with radiogenic Nd (island-arc components in the Pacific and LREE-enriched intraplate ocean island components in the Atlantic). Samples from the north central Pacific have distinctive unradiogenic epsilon-Nd values of -10, 87Sr/86Sr > 0.715, high La/Yb (> 12), and low EuN/EuN* (0.6) and Sr/Nd (3-6). These data are virtually identical to the values for loess from Asia and endorse the use of these sediments as indicators of Asian paleoclimate and paleowind directions. Island-arc contributions appear to dominate in the northwest Pacific, resulting in higher epsilon Nd (-1 to +1) and lower 87Sr/86Sr (~ 0.705) and La/Yb (~ 5). Sediments from the eastern Pacific tend to have intermediate Sr and Nd isotopic compositions but regionally variable Sr/Nd and REE patterns; they appear to be derived from the west margin of the North and South American continents, rather than from Asia. Our results confirm that dust provenance can be constrained by isotopic and geochemical analyses, which will facilitate reconstructions of past atmospheric circulation and continental paleoclimate.

Nd isotope ratios of surface sediments from the Pacific Ocean (Table 2)

The neodymium isotopic composition of the silicate fraction of Holocene pelagic sediments from the North Pacific define two provinces: a central North Pacific province characterized by unradiogenic and remarkably homogeneous end (-10.2 +/- 0.5) and a narrow circum-Pacific marginal province characterized by more radiogenic and variable end (-4.2 +/- 3.8). The silicate fraction in the central North Pacific is exclusively eolian; based on prevailing wind patterns, meteorological data, and neodymium isotopic data, the only significant sediment source is Chinese loess. Leaching experiments on Chinese loess confirm that leachable Nd is isotopically indistinguishable from bulk and residual silicate Nd. Silicates in the circum-North Pacific marginal province comprise eolian loess, volcanic ash, and hemipelagic sediments derived from volcanic arcs. A compilation of Pacific seawater and Mn nodule epsilon-Nd data shows no clear spatial variation except for a general decrease from surface to deep waters from -3 to -4 and slightly lower epsilon-Nd in bottom waters along the western North Pacific due to the incursion of Antarctic Bottom Water. The relative homogeneity of bottom water epsilon-Nd, which contrasts sharply with the distinctive variation in sediment epsilon-Nd, plus the large difference between the average end of bottom waters and the central North Pacific eolian silicates (-4 vs. -10), suggests that any contribution of REE to seawater from eolian materials is insignificant. Furthermore, leaching of REE from eolian particles as they sink though the water column must be insignificant because Nd in shallow waters is more radiogenic than Nd in deeper waters. That there is no contrast in the Nd isotopic composition of bottom waters that overlie the central and marginal sediment provinces suggests that the ash and hemipelagic sediments derived from Pacific rim volcanic arcs also contribute minimal REE to seawater. The elimination of eolian, ash, and hemipelagic sediments leaves only near-shore riverine particulates as a possibly significant particulate source of REE to seawater.