Indicator mineral and till geochemical methods for kimberlite exploration in glaciated terrain

CIM Vancouver 2002
Abstract Kimberlite is a mineralogically and chemically
distinct point source which may yield discrete
dispersal trains in glacial sediments.
Understanding the ice flow history and
depositional history of glacial sediments and
identifying multiple till sheets in areas covered
by thick glacial sediments are essential to
successful sampling, interpretation and follow-up
of indicator mineral and geochemical anomalies
related to these rocks. Kimberlite indicator
minerals survive glacial transport over long
distances. Indicator mineral distributions
observed at a regional scale define the net effect
of glacial dispersal, often along different ice
flow directions. Local scale distributions define
individual dispersal trains and the relative
abundance of each mineral in till is a function of
the primary mineralogy of individual kimberlites.
The finer (0.25 to 0.5 mm) fraction of heavy
mineral concentrates prepared from till samples is
best suited for indicator mineral surveys. Till
geochemistry is gaining popularity in diamond
exploration because of its lower cost and quick
turn-around time. Kimberlite pathfinder elements
that provide good contrast in till geochemical
surveys include Ni, Cr, Ba, Co, Sr, Rb, Nb, Mg,
Ta, Ca, Fe, K, Ti and REE, the relative importance
of which will depend on kimberlite composition as
well as that
Keywords: diamond exploration, Till, Glaciated terrain, indicator minerals, Kimberlite
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