Hemipelagic sediments

Goodfellow, W.D. and Blaise, B. (1988) Sulfide formation and hydrothermal alteration of hemipelagic sediment in Middle Valley, northern Juan de Fuca Ridge. Can. Mineral, 26, 675-696. 

Hemipelagic sediments Sediments that lie in water depths of 200 to 3000 m (roughly encompassing the continental slope and upper part of the rise). 

Stolz, J.E. Chang, S.R. Kirschvink, J.L (1986) Magnetotactic bacteria and single-domain magnetite in hemipelagic sediments. Nature 321 849-851... 

Aller, R.C. (1990) Bioturbation and manganese cycling in hemipelagic sediments. Phil. Trans. Royal Soc. London 331, 51-68. 

AUer, R. C., HaU, P. O. J., Rude, P. D., and AUer, J. Y. (1998). Biogeochemical heterogeneity and suboxic diagenesis in hemipelagic sediments of the Panama Basin. Deep-Sea Research Part I-Oceanographic Research Papers. 45(1), 133—165. 

Murray J. W. and Kuivila K. M. (1990) Organic matter diagenesis in the northeast Pacific transition from aerobic red clay to suboxic hemipelagic sediments. Deep-Sea Res. 37, 59-80. 

Arthur, E., Carson, B. and von Huene, R. 1980. Initial tectonic deformation of hemipelagic sediment at the leading edge of the Japan convergent margin. Initial Report Deep Sea Drilling Project, 56, 57, part 1, pp. 569-613. 

The hemipelagic sediments are basically made of the same components as the deep-sea red clay... 

Fig. 1.9 Hemipelagic sediment from Sierra Leone Rise, tropical North Atlantic. Left Fine silt-size fraction composed of coccoliths (c), foraminiferal fragments (f) and of detrital quartz (q) and mica (m). Right Coarse silt-sized fraction predominately composed of foraminiferal fragments (f), some detrital quartz (q) and mica (m), scalebar 10 pm.

Fig. 7.16 Pore water and extraction results from hemipelagic sediments off Uruguay (redrawn from Haese et al. 2000). Dissolution and precipitation of Fe is reflected by the easy reducible iron oxyhydroxide fraction whereas less reducible iron oxides soluble by subsequent citrate/dithionite/bicarbonate (CDB) extraction remain constant. A concurrent liberation of Mn and Fe indicates dissimilatory iron reduction and subsequent iron reoxidation by manganese oxides, which results in the build-up of Mn Under these conditions the actual dissimilatory iron reduction rate is higher than deduced from iron pore water gradients.

Karlin, R. and Levi, S., 1983. Diagenesis of magnetic minerals in recent hemipelagic sediments. Nature, 303 327-330. 

In a comparison of pore water profiles of red clays and hemipelagic sediments, Sawlan and Murray (1983) showed that Mn and Fe are below the detection limit in the pore waters of red clays, Ni is present in the same concentation as in ocean bottom water and Cu shows a pronounced maximum at the sediment-water interface. In hemipelagic clays, denitrification becomes important and remobilization of Mn and Fe takes place. Ni correlates with Mn in the pore waters suggesting that it is associated with the Mn oxides in the solid phase. Cu is regenerated very rapidly at the sediment-water interface. The diffusive flux of Mn in hemipelagic sediments was determined to be in the range 2,200-... 

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