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Tree ferns and tea trees in biogeochemical exploration for epithermal Au and Ag in New Zealand

C. E. Dunn and A. B. Christie
Tree ferns and tea trees in biogeochemical exploration for epithermal Au and Ag in New Zealand
Geochemistry - Exploration, Environment, Analysis (July 2019) Pre-Issue Publication


Biogeochemical orientation surveys were undertaken at low sulphidation epithermal Au-Ag occurrences in the Hauraki Goldfield - Coromandel Volcanic Zone (CVZ) and Taupo Volcanic Zone (TVZ), and at the Waiotapu active geothermal area in the TVZ. Several plant species were sampled including the foliage of tree ferns and tea trees. The ferns - silver fern ('ponga'), rough tree fern ('wheki') and black tree fern ('mamaku') - were the most ubiquitous and were easiest to sample, although tea tree was the dominant genus at Waiotapu. At the Waiotapu geothermal area, significantly higher concentrations of Ag, Au, Sb, As, Cs and Rb were present in samples close to Champagne Pool than elsewhere confirming its location as the main outflow source of Au, Ag and their pathfinder elements. The fern survey areas at Luck at Last mine, Pine Sinter and Ohui in the CVZ each exhibited biogeochemical anomalies which successfully highlighted most known quartz veins and provided additional anomalies for further investigation. At Goldmine Hill, Puhipuhi (TVZ), rough tree fern is the most common species. Although this species absorbs lower concentrations of many elements than the silver fern, the spatial distribution of elements is of greater significance than absolute concentrations. Highest Au, Ag, As and Al concentrations occurred in samples from a ridge extending west-north-westward from Goldmine Hill. Antimony and Bi were at anomalous levels in an area peripheral to the precious metal anomalies, indicating potential zonation of elements distal from the Au and Ag.

ISSN: 1467-7873
EISSN: 2041-4943
Serial Title: Geochemistry - Exploration, Environment, Analysis
Serial Volume: Pre-Issue Publication
Title: Tree ferns and tea trees in biogeochemical exploration for epithermal Au and Ag in New Zealand
Affiliation: Colin Dunn Consulting, North Saanich, BC, Canada
Published: 20190725
Text Language: English
Publisher: Geological Society Publishing House, London, United Kingdom
References: 43
Accession Number: 2019-065674
Categories: Economic geology, geology of ore deposits
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 5 tables, sketch maps
S37°10'60" - S36°28'60", E175°19'60" - E175°55'00"
Secondary Affiliation: GNS Science, NZL, New Zealand
Country of Publication: United Kingdom
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data from The Geological Society, London, London, United Kingdom
Update Code: 201934
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