Geology topics

D.Z. Piper

Publications and source records attributed to D.Z. Piper.

40 records · Page 3Linked to original sources

USGS1980

New constraint on the maintenance of Mn nodules at the sediment surface

Investigations into the association of manganese nodules with pelagic sediment in many areas of the deep ocean have mainly considered either (1) the source of metals in nodules, or (2) the occurrence of nodules predominantly at the sediment surface. The second problem is duscussed here. The mechanisms previously proposed have failed to consider that nodules retain their orientation at the sediment surface for several hundred-thousand years, during which time several tens of centimetres of sediment are fluxed down beneath them. Although we have no conclusive evidence, we consider the most plausible explanation for the surface occurrence of nodules to be bioturbation by infauna. ?? 1980 Nature Publishing Group.

Nature↗

USGS1980

Treasures from the deep ( Metallic nodules).

The composition, distribution, metric growth rates and variations in sea-floor metallic nodules are outlined and discussed The considerable age, slow accretion and relationship to underlying sediments are problems of origin which are yet to be solved and some speculative answers are discussed. Mining of the nodules is reviewed and its related difficulties mentioned.-D.A.Lewis

Water Spectrum↗

USGS1978

Cobalt and scandium partitioning versus iron content for crystalline phases in ultramafic nodules

Fractionation of Co and Sc between garnets, olivines, and clino- and orthopyroxenes, separated from a suite of Salt Lake Crater ultramafic nodules that equilibrated at the same T and P , is strongly dependent on Fe contents. This observation suggests that petrogenetic equilibrium models of partial melting and crystal fractionation must take into account effects of magma composition, if they are to describe quantitatively geochemical evolutionary trends.

Earth and Planetary Science Letters↗

USGS1977

Rapidly-formed ferromanganese deposit from the eastern Pacific Hess Deep

A thick ferromanganese deposit encrusting fresh basaltic glass has been dredged from the Hess Deep in the eastern Pacific. Contiguous layers within the Fe-Mn crust have been analysed for uranium-series isotopes and metal contents. The rate of accumulation of the deposit, based on the decline of uranium-unsupported 230Th, is calculated to be approximately 50 mm per 106 yr. Based on hydration-rind dating of the underlying glass and an 'exposure age' calculation, this rate is concluded to be too slow, and an accretion rate on the order of 1 mm per 103 yr is more consistent with our data. ?? 1977 Nature Publishing Group.

Nature↗