DETERMINATION OF TRACE ELEMENTAL SIGNATURES IN PLACER GOLD BY LASER-ABLATION INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY AS A POTENTIAL AID FOR GOLD EXPLORATION
Pm. Outridge et al., DETERMINATION OF TRACE ELEMENTAL SIGNATURES IN PLACER GOLD BY LASER-ABLATION INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY AS A POTENTIAL AID FOR GOLD EXPLORATION, Journal of geochemical exploration, 60(3), 1998, pp. 229-240
It is possible that placer gold retains the trace element composition
('signature') of the pal ent lode. Laser ablation-inductively coupled
plasma-mass spectrometry (LA-ICP-MS) offers sensitive detection limits
of 59 elements with sub-millimetre sample spot sizes, ideal for signa
ture analysis of placer. Here, the optimum laser parameters, analytica
l precision and reproducibility of elemental signatures are determined
in placer nuggets by infrared LA-ICP-MS. The highest precision was of
fered by Q-switched ablation at a relatively low energy level; using A
u as an internal standard; these parameters gave median precision valu
es of 33-82% RSD for trace elements in nuggets. In addition to major c
onstituents such as Ag, Cu and Hg, placer from several rivers world-wi
de commonly contained a wide range of trace elements including, in som
e cases, unusual REE patterns. At least two distinct signatures could
be distinguished in placer fi om most of the rivers examined, while mu
ltiple examples of certain signatures were also seen. Tracking these s
ignatures back to their original tributaries may offer a means of iden
tifying the number and approximate location of deposits within a river
watershed, thereby significantly aiding exploration. (C) 1998 Elsevie
r Science B.V.