Carbon isotopic composition and dissolved CO2 concentration in pore waters of ODP Leg 174A sites

Microbially mediated redox diagenetic processes in marine sediments are reflected in the amount and carbon isotopic composition of dissolved CO2 and CH4 (Claypool and Kaplan, 1974). Oxidation of organic matter gives rise to dissolved CO2 with about the same 13C/12C ratio as the starting organic matter. Subsequent reduction of CO2 to form CH4 involves a large (~70) kinetic isotopic effect, resulting in significant 13C depletion in the CH4, and 13C enrichment in the residual CO2. Ocean Drilling Program Leg 174A (offshore New Jersey) presented an opportunity to study these processes in shelf and upper slope sediments. Holes 1071A-1071D, 1071F, and 1072A were drilled on the shelf in water depths of 88.0-98.1 m. Hole 1073A was drilled on the slope in 639.4 m of water. Pore-water samples were collected for analysis at all three sites, whereas gas samples could only be obtained from Hole 1073A on the slope.

Grain size analyses of ODP Leg 116 holes

Ocean Drilling Program (ODP) Leg 116 cored the distal part of the Bengal Fan at three closely spaced sites (717-719). The recovered sediments consisted dominantly of turbidites that varied in thickness between a few centimeters and 2 m or more. A number of different facies have been identified in the sequence and are described by Stow et al. (1990, doi:10.2973/odp.proc.sr.116.110.1990). Representative examples of these facies types were selected and sampled for grain-size analysis. The results of these analyses are tabulated in this data report.

Geochemistry and structural formulas of heavy minerals from sands and sandstones of ODP Leg 126 samples

Lower Oligocene to Pleistocene volcaniclastic sands and sandstones recovered around the Izu-Bonin Arc during Ocean Drilling Program Leg 126 were derived entirely from Izu-Bonin Arc volcanism. Individual grains consist of volcanic glass, pumice, scoria, basaltic or andesitic fragments, plagioclase, pyroxene, and minor olivine and hornblende. In Pliocene-Pleistocene samples plagioclase and heavy minerals in the volcaniclastic sands and sandstones are present in the following abundances: plagioclase > orthopyroxene > clinopyroxene > pigeonite > olivine. In contrast, plagioclase and heavy minerals found in Oligocene-Miocene samples occur in the following order: plagioclase > clinopyroxene > orthopyroxene > hornblende. The low concentration of Al, Ti, and Cr in calcium-rich clinopyroxenes in Oligocene to Holocene sediments suggests that the sources of the volcaniclastic detritus were nonalkalic igneous rocks. There are, however, some distinctive differences in the chemical composition of pyroxene between the Pliocene-Pleistocene and Oligocene-Miocene volcaniclastic sands and sandstones. Orthopyroxene belongs to the hypersthene-ferrohypersthene series (Fe-rich) in Pliocene-Pleistocene sediments, and the bronzitehypersthene series (Mg-rich) in Oligocene-Miocene sediments. Clinopyroxene is characterized by augite and pigeonite in Pliocene-Pleistocene sediments, and by the diopside-augite series in Oligocene-Miocene sediments. Mineral assemblages and mineral chemistry of the volcaniclastic sands and sandstones reflect those of the volcanic source rocks. Therefore, the observed changes in mineralogy record the historical change in volcanism of the Izu-Bonin Arc. The mineralogy is consistent with the geochemistry of the volcaniclastic sands and sandstones and the geochemistry of forearc volcanic rocks of the Izu-Bonin Arc since the Oligocene.

(Table 2) Major and trace element content of ODP Leg 130 basalts

Estimated relative errors on major and minor elements are 1%. For trace elements, errors (% standard deviation at levels measured) are estimated at 1 % for Cr, 3% for Ni, 3% for Rb at 30 ppm, and >20% at < 10 ppm; 2% for Sr and V, and 4% for Y and Zr.

Eolian accumulation rates of ODP Leg 121 holes

The late Cenozoic history of eolian sedimentation in the eastern Indian Ocean was developed from samples recovered during drilling of Sites 752, 754, and 756. Temporal changes in the mass accumulation rate of eolian material reflect major climatic shifts in the southern African source region. A significant drop in dust mass flux values occurs near the end of the lower Oligocene. Younger sediments are characterized by a gradual reduction in dust accumulation rates until the middle Miocene after which values remain consistently low throughout the late Cenozoic, although a slight increase in eolian accumulation rate occurs near 2.5 Ma. This pattern of dust mass flux appears related to the supply of dust-sized particles in the source region and represents a shift in the climatic regime of southern Africa to increasingly more arid conditions throughout the late Cenozoic.