Conference Proceedings
1992 AusIMM New Zealand Branch Annual Conference
Conference Proceedings
1992 AusIMM New Zealand Branch Annual Conference
Physical and Chemical Recycling of Placer Gold: Implications for Exploration in Central Otago
Uplift of the antiformal ranges in Central Otago, New Zealand , has resulted in the progressive evolution of eluvial placer deposits in tectonic sediments on the range flanks and along their margins. The placers are derived from the reworking of fine-grained gold from the auriferous Manuherikia Group fluvial sediments which covered the basement prior to uplift of the ranges. Gold in the tectonic sediments at Matakanui shows a progressive increase in grainsize in successively younger sediments and nuggets in the youngest gravel sequence are up to two orders of magnitude larger than gold grains in the parent alluvial source. Most of the gold in the tectonic sediments is highly irregular in shape, commonly with delicate surface textures which could not have survived fluvial transport and are indicative of authigenic precipitation. Some coarse grains have been rounded by recycling, and further addition of authigenic gold has occurred. Placer gold values result from both physical and chemical enrichment during sedimentary recycling. Continued range uplift and back-thrusting of sediments on to the ranges results in recycling of earlier formed placer sediments. They also result in further enrichment of gold values through the incorporation of additional supplies of the parent alluvial source sediment The host sediments are widespread along the ranges and are not confined to sites of historic mining activity.
Contributor(s):
J H Youngson, D Craw
-
Physical and Chemical Recycling of Placer Gold: Implications for Exploration in Central OtagoPDFThis product is exclusive to Digital library subscription
-
Physical and Chemical Recycling of Placer Gold: Implications for Exploration in Central OtagoPDFNormal price $22.00Member price from $0.00
Fees above are GST inclusive
PD Hours
Approved activity
- Published: 1992
- PDF Size: 1.251 Mb.
- Unique ID: P199212003