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Geology topics

K.B. Krauskopf

Publications and source records attributed to K.B. Krauskopf.

3 recordsLinked to original sources
USGS1956

Factors controlling the concentrations of thirteen rare metals in sea-water

The following factors controlling the concentrations of thirteen metals (Zn, Cu, Pb, Bi, Cd, Ni, Co, Hg, Ag, Cr, Mo, W, V) in sea-water were studied: 1. precipitation of insoluble compounds with ions normally present in aerated sea-water, 2. precipitation of sulphides locally in reducing environments, 3. adsorption by ferrous sulphide, hydrated ferric oxide, hydrated manganese dioxide, apatite, clay, and organic matter. The precipitation reactions were investigated first by calculations based on solubility data, and then by experiments in which equilibrium concentrations of the metal ions were determined in sea-water in contact with their precipitates. Adsorption was measured by adding or precipitating the various adsorbents in sea-water samples containing an excess of one of the metal ions. The principal conclusions are: 1. Sea-water is greatly undersaturated with respect to all thirteen metals; in other words, precipitation of compounds with the ions normally present in aerated sea-water, even under extreme conditions of temperature and pH, cannot be responsible for the observed concentrations. 2. Local precipitation of sulphides is a possible control mechanism for seven of the elements (Cu, Zn, Hg, Ag, Cd, Bi, Pb), but is probably not the chief control, because the concentrations are unrelated to sulphide solubilities. 3. Adsorption is a possible mechanism for all elements except V, W, Ni, Co, and Cr; if Cr is assumed to be removed by local reduction and precipitation of the hydroxide, and the other four metals by organic reactions, the existing concentrations can be fairly adequately accounted for. Adsorption processes supplemented by organic reactions also furnish a qualitative explanation for the distribution of rare metals in sedimentary rocks of marine origin. These conclusions can probably be extended to other metals in the middle of the periodic system, but not to those on either side.

Geochimica et Cosmochimica Acta↗
USGS1948

Lava movement at Parícutin Volcano, Mexico

The lava flows of Parícutin Volcano, Mexico, offer an exceptional opportunity to study details of lava movement, because many flows are accessible throughout their length and can be watched from their birth to the cessation of their movement. Petrographically the lavas show no significant difference from one flow to another or in different parts of the same flow. The maximum lava temperature observed was 1070°C.; the maximum estimated rate of flow was 60 meters per minute; the viscosity is probably on the order of 10 5 to 10 6 poises. The flows start in fissure zones cutting older Parícutin lavas near the southwest base of the volcano. Within a short distance of its orifice a flow is covered with cooled blocks which are broken and slightly abraded as they are carried downstream. Differential movement in a flow takes place principally at its edges, where a reddish breccia and grooved and slickensided surfaces form. Like a glacier, a lava flow develops transverse crescentic ridges and lateral moraines. At its front movement is normally effected by the rolling forward of molten lava within, which carries down cooled blocks from the surface and piles them up ahead of the flow. As a flow dies the lava level lowers in the channel, and small side tongues break through the moraines. Some Parícutin lavas move considerable distances beneath older lava. The longest flow, which covered the town of San Juan in 1944, has a surface of rough curved slabs very different from the blocky surface of other flows but similar to the surface structures developed near lava orifices and by movement of viscous lava through fissures.

Michoacan↗