Skip to Main Content
GEOREF RECORD

Round Hill shear zone-hosted gold deposit, Macraes Flat, Otago, New Zealand; evidence of a magmatic ore fluid

Cornel E. J. de Ronde, Kevin Faure, Colin J. Bray and David J. Whitford
Round Hill shear zone-hosted gold deposit, Macraes Flat, Otago, New Zealand; evidence of a magmatic ore fluid
Economic Geology and the Bulletin of the Society of Economic Geologists (August 2000) 95 (5): 1025-1048

Abstract

The 0.8 M oz Round Hill Au deposit is one of several located on or near the Hyde-Macraes shear zone, N of Dunedin. Field relationships show that stockwork veins are the oldest part of the hydrothermal system, followed by flat and ramp veins. Fluid inclusions are dominated by aqueous, low-salinity, CO (sub 2) -bearing fluids. CO (sub 2) ranges from 0.14 and 0.76 mol.% and accounts for approximately 1/3 of the freezing point depressions (apparent salinities). Early stockwork veins have fluid inclusions with salinities < 1 wt.% NaCl equivalent. Detection of Li (more rarely K and Mg), together with (super 87) Sr/ (super 86) Sr data and delta (super 18) OH (sub 2) O values, provide evidence for interaction with the surrounding country rock. Au mineralization at Macraes is a result of mixing between equilibrated meteoric water and a magmatic water component. Evidence for this mixing comes from higher salinities for inclusions in flat and ramp veins, when compared to early stockwork and hanging-wall veins, and fluid inclusion delta DH (sub 2) O values.


ISSN: 0361-0128
EISSN: 1554-0774
Coden: ECGLAL
Serial Title: Economic Geology and the Bulletin of the Society of Economic Geologists
Serial Volume: 95
Serial Issue: 5
Title: Round Hill shear zone-hosted gold deposit, Macraes Flat, Otago, New Zealand; evidence of a magmatic ore fluid
Affiliation: Institute of Geological and Nuclear Sciences, Lower Hutt, New Zealand
Pages: 1025-1048
Published: 200008
Text Language: English
Publisher: Economic Geology Publishing Company, Lancaster, PA, United States
References: 60
Accession Number: 2001-003067
Categories: Economic geology, geology of ore deposits
Document Type: Serial
Bibliographic Level: Analytic
Annotation: Includes appendix
Illustration Description: illus. incl. sects., 5 tables, sketch map
S46°40'60" - S44°16'00", E166°25'00" - E171°07'60"
Secondary Affiliation: Geological Survey of Japan, JPN, JapanUniversity of Toronto, CAN, CanadaCSIRO, AUS, Australia
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
Update Code: 200101
Close Modal
This Feature Is Available To Subscribers Only

Sign In or Create an Account

Close Modal
Close Modal