| Zusammenfassung: |
Drift prospecting in glaciated terrain is based on the premise that geochem...
Drift prospecting in glaciated terrain is based on the premise that geochemical, mineralogical, isotopic and lithological indicators of economic mineralization recovered from sediments can be traced back to their primary bedrock source by reconstructing the glacial flow history. It is increasingly recognized however, that simple linear, one or two dimensional reconstructions of past glacial flow direction(s) do not capture the complex history of glacial erosion, entrainment and deposition. Greater understanding of what is often a palimpsest glacial history, means of entrainment, and variations in the nature of glacial dispersal such as glacial sediment thickness, bedrock topography, bedrock erodibility, and basal glacial flow velocities are required to accurately determine an up-ice bedrock source. Development of complex ice sheet models, and the acquisition of empirical ice-flow records, drift composition, and glacial history over the last two decades have increased the accuracy and efficiency of drift prospecting in Canada. Increased attention to the dynamic nature of glacial dispersal centers and related ice-flow complexes has become increasingly important. Recognition of relict ice-flow trajectories from multiple glaciations puts in perspective the complexity of the former Laurentide Ice Sheet and has important implications for the interpretation of compositional data generated by regional till surveys. Continental-scale interpretations and small-scale remote sensing imagery of the glacial system of North America are lacking in the deciphering of glacial dispersal trains and property-scale mineral exploration, often failing to recognize the key details that field investigations have revealed. Regional and local-scale mapping of all glacial flow indicators, sediment stratigraphy and derived interpretations are proven to be most effective. The message for exploration is that relations among bedrock, drift composition and ice flow history must be inferred in both regional and local context of the ice sheet and glacial history in order to successfully decipher drift prospecting data.
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