Page 280 - Handbook of Gold Exploration and Evaluation
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4.28 Depositional environments and typical vertical profiles of facies deposited
during a single phase of glacial advance and retreat in various glacio-terrestrial and
glacio-marine environments (after Eyles and Eyles, 1992).
weathering in a boreal weathering system. The basic problem is to recognise
those elements of a landscape that were adjusted to the base level at the time of
their formation and to fix their elevation relative to the present time. Analysing
these environments and the sequence of geological events is essential to the
study of glacial gold placer development.
The spatial and chronological linkage of depositional environments in Fig.
4.28 identifies two distinctive system tracts during a single phase of glacier
advance and retreat in various glacio-terrestrial and glacio-marine environments.
Cyclicity of these glaciations is proposed for the high rate of colluvium derived
by chemical weathering in humid intervals and concomitant colluvial
encroachment in valleys of those times.
Pleistocene glaciations
Glacial erosion of primary gold placers in the Pleistocene contributed to the
evolution of secondary placers in several ways:
