Dispersion hydromorphic

Fig. 1. Distribution of Hg (and Cd) in till at the MFN deposit. DDH MF00-31 and DDH MF00-29 are marked with an X subcropping mineralization is marked by a dashed line. Arrows indicate ice flow directions, the youngest flow was northeastward, elements by electrochemical mechanisms and hydromorphic dispersal. These conclusions are supported by qualitative mass balance calculations and variable geochemical distribution patterns in till, in the context of local and regional ice flow.

KEYWORDS uranium, aqueous chemistry, redox equiiibria, radon, hydromorphic dispersion... 

The rationale for using Hg as a pathfinder element in mineral exploration is attractive. Because of its volatility, Hg is presumed to form broader halos in the hypogene environment than most elements. It is envisaged that both vapour-phase and solution transport are responsible for a wide dispersion of the element. In the secondary environment it is well known that Hg exerts a measurable vapour pressure at ambient temperatures and possesses redox properties that allow the metal to exist in the elemental state under a range of natural conditions. Therefore it has been claimed that, as a host sulphide-body weathers, it can be expected that Hg will be converted partly to the vapour state, thereby overcoming the constraint of hydromorphic or solution dispersion that applies to other target and indicator elements. Vapour-phase dispersion through permeable rock or cover would allow Hg to be detected in soil or soil gas, and perhaps as an atmospheric anomaly. 

Because of its almost universal association with porphyry copper deposits and its mobility characteristics. Mo has been used extensively as a pathfinder element for geochemical prospecting for porphyry copper deposits (Rose, Hawkes, and Webb, 1979). Dispersion of Mo in mineralized areas has been shown to occur by both hydromorphic (Bradshaw, 1974) and mechanical (Hansuld, 1966) processes. 

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