Ba, Al and SO4 concentrations in sediments and pore fluid of ODP Leg 127/128 samples

The barium distribution in sediments and pore fluids from five sites drilled in the Japan Sea have been used to illustrate the geochemical behavior of this element as it pertains paleoproductivity reconstructions, diagenetic remobilization, and barite precipitation in authigenic fronts. Sites where sulfate is depleted in the pore fluids also show high concentrations of dissolved barium, reflecting dissolution of biogenic barite. The high rate of sedimentation at Sites 798 and 799 results in a rapid sulfate depletion, which in turn leads to barite dissolution and reprecipitation in diagenetic fronts. The dissolved barium distribution at these sites has been used to quantify the rate of barite dissolution; we estimate a first-order rate constant for barite dissolution to be 2*10**-6/s at Site 799 and 2*10**-7/s at Site 798. Authigenic barite has been documented in sediments from Site 799 at 323 meters below seafloor by scanning electron microscopy and X-ray fluorescence analysis. These results indicate barite precipitation in a diagenetic front near the zone of sulfate depletion by upward migration of dissolved barium and downward diffusion of sulfate. Barite precipitation has also been inferred at Sites 796 and 798 based on sedimentary and dissolved barium distributions. Sulfate is not depleted in the pore fluids of Site 794. The lack of diagenetic remobilization of biogenic barium at this site preserves the high barium signal associated with the high-productivity sequences deposited during the late Miocene to Pliocene. Significantly, the organic carbon distribution does not indicate high accumulation rates during the periods of high opal and barium deposition. Instead, higher organic carbon accumulations are recorded in the Quaternary and middle Miocene sequences; intervals that are also characterized by deposition of siliciclastic turbidites. The presence of a terrestrial component in the organic carbon record renders barium a more useful indicator than organic carbon for paleoproductivity reconstructions in this marginal sea.

Experimental petrology of basement basaltic rocks from ODP Leg 127/128 samples

The relatively fresh basement basaltic rocks cored at Sites 794 and 797 during ODP Legs 127 and 128 show compositional variations suggesting the following: (1) the aphyric rocks might be differentiated from compositional equivalents of the aphyric sample with the lowest FeO*/MgO (Sample 127-797C-12R-4, 35-37 cm); and (2) the plagioclase-phyric rocks (i.e., another constituent of the basement basaltic rocks from the sites) may be derivatives from the same parents; in this case, however, crystallized plagioclase was not effectively removed. Melting experiments were conducted for Sample 127-797C-12R-4, 35-37 cm, and the differentiation processes for the basement basaltic rocks were assessed. The high-pressure melting-phase relation can not account for the compositional variation of the aphyric rocks, suggesting that the variation was developed at relatively low pressure where olivine and plagioclase fractionation was followed by Ca-rich clinopyroxene fractionation. The density of Sample 127-797C-12R-4,35-37 cm, is comparable to that of plagioclase at some depth, but at still relatively low pressure, making it possible that the liquidus plagioclase was retained in the successive liquids to produce the plagioclase-phyric rocks. According to backtrack calculation assuming the olivine maximum fractionation, Sample 127-797C-12R-4, 35-37 cm, was differentiated from primary picritic high-Al basalt magma. The estimated primary magma composition was experimentally proved to coexist with harzburgite mantle at about 14 kbar, suggesting relatively shallow production (approximately 40-50 km below surface) of the rifting-related primary magma.

Distinguishing attack on SOBER-128 with linear masking

We present a distinguishing attack against SOBER-128 with linear masking. We found a linear approximation which has a bias of 2^− − 8.8 for the non-linear filter. The attack applies the observation made by Ekdahl and Johansson that there is a sequence of clocks for which the linear combination of some states vanishes. This linear dependency allows that the linear masking method can be applied. We also show that the bias of the distinguisher can be improved (or estimated more precisely) by considering quadratic terms of the approximation. The probability bias of the quadratic approximation used in the distinguisher is estimated to be equal to O(2^− − 51.8), so that we claim that SOBER-128 is distinguishable from truly random cipher by observing O(2^103.6) keystream words.