Determining sources of placer minerals using U-Pb ages of detrital zircons: example of auriferous quartz pebble conglomerates in Otago and Southland, New Zealand

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Authors

Nicholas Mortimer, J Michael Palin, Paul Wopereis

Abstract

We have dated populations of detrital zircons in two Miocene gold-bearing quartz pebble conglomerates, one at
St Bathans in Central Otago and one near Gore in Northern Southland. Both samples contain large numbers of
Triassic-Permian zircon grains that indicate a source area dominated by Eastern Province Torlesse Composite
Terrane protoliths. On the basis that the detrital quartz, zircon and gold are derived from the same source, we can
thus confirm a textural zone IV Otago Schist source for the gold content of both Miocene deposits. Hypotheses
invoking a Western Province Buller Terrane (e.g. Reefton) source for Central Otago gold are thus refuted. Our
investigation highlights the power of the detrital zircon dating method to identify and/or confirm suspected
sources of economic placer minerals.

DOI

https://doi.org/10.31223/osf.io/xv56g

Subjects

Earth Sciences, Geology, Physical Sciences and Mathematics

Keywords

provenance, U-Pb dating, Zircon, gold, Miocene, placer

Dates

Published: 2019-03-01 03:17

License

CC BY Attribution 4.0 International