Mass-accumulation rates for the non-authigenic, inorganic, crystalline, eolian component of sediments recovered at DSDP Sites 62-464 to 62-466

The mass-accumulation rate (MAR) of the non-authigenic, inorganic, crystalline component of deep-sea sediments from the Pacific aseismic rises apparently reflects influx of eolian sediment. The eolian sediment usually is dominated by volcanic material, except during glacial times. Sediments from Hess Rise provide a discontinuous record of eolian MARs. During Albian to Cenomanian time, the influx of volcanic material was fairly high (0.35-0.6 g/cm**2/10**3 yr), recording the latest stages of the Albian volcanism that formed Hess Rise. From the Campanian through the Paleocene, influx of eolian sediment was low, averaging 0.03 g/cm**2/10**3 yr. None of the four Hess Rise drill sites show evidence of the Late Cretaceous volcanic episode recorded at many sites now in the equatorial to subtropical Pacific. Pliocene to Pleistocene samples record a peak in volcanic influx about 4 to 5 m.y. ago, which has been well documented elsewhere. The several-fold increase in eolian accumulation rates elsewhere which are correlated with the onset of severe northernhemisphere glaciation 2.5 m.y. ago is not obvious in the Hess Rise data.

Flow rates, hydraulic conductivities and permeabilities of sediments from ODP Holes 190-1173A and 190-1174B

Understanding the role of fluids in active accretionary prisms requires quantitative knowledge of parameters such as permeability. We report here the results of permeability tests on four samples from Ocean Drilling Program Leg 190 at the Nankai Trough accretionary prism-two from Site 1173 and two from Site 1174. Volcanic ash is present in one of the samples; otherwise, the material is hemipelagic mud. A constant-rate-of-flow technique was used at various effective pressures and rates of flow. The permeability of the four samples ranges between 10**-15 and 10**-18 m**2, with the ash-bearing sample showing the highest values.