Young porphyries, old zircons: new constraints on the timing of deformation and gold mineralisation in the Eastern Goldfields from SHRIMP U-Pb zircon dating at the Kanowna Belle Gold Mine, Western Australia
MetadataShow full item record
The Kanowna Belle Gold Mine is a Late Archaean orogenic lode-gold deposit hosted by felsic volcaniclastic and intrusive rocks (porphyries) of the Kalgoorlie Terrane, Western Australia. Rare gold occurs in fragments of veins and alteration that form clasts within the Black Flag Group volcaniclastic rocks at the Kanowna Belle mine, indicating that epithermal gold mineralisation accompanied Black Flag Group volcanism. The SHRIMP U-Pb zircon age of the volcaniclastic unit is 2668 9 Ma, and xenocrystic zircons with ~2.68, 2.70 and 2.71 Ga age groupings are common. The Black Flag Group rocks are faulted by a D1 thrust, and ~2670 Mais thus an older limit for regional D1 deformation. Although SHRIMP U-Pb zircon ages of felsic porphyries commonly give the best constraints on the timing of deformation and structurally controlled gold mineralisation, the data are complex and dates from single samples can be ambiguous. Four Porphyry samples from the Kanowna Belle Gold Mine were analysed. Back scattered electron and cathodoluminescence imaging show that most magmatic zircon in the porphyries is either high-U and metamict, or restricted to rims on older xenocrysts that are too narrow to be dated by SHRIMP. Some porphyries appear to have been saturated with zircon at source and contain only xenocrystic zircons.Zircons that are interpreted to be magmatic in a sample of the mineralised Kanowna Belle Porphyry gives a mean age of 26556 Ma. The Kanowna Belle Porphyry is cross cut by regional D2 fabrics and ~2655 Ma is thus the maximum age for regional D2 deformation. This is a maximum age for epigeneticlode-gold mineralisation. The age of resetting of high-U zircon grains (2.63 Ga) and the age of ore-related Pb-Pb galenas (2.63 Ga) serves as an approximate date for lode-gold mineralisation. If the complex zircon history of the felsic porphyries at Kanowna Belle is typical of this suite throughout the Eastern Goldfields Province, it is clear that existing single zircon dates from this Province require reevaluation, backed up by careful backscattered and cathodoluminescence imaging and textural studies.
The link to the journal’s home page is: http://www.elsevier.com/wps/find/journaldescription.cws_home/503357/description#description. Copyright © 2004 Elsevier B.V. All rights reserved
Showing items related by title, author, creator and subject.
Long-lived, autochthonous development of the archean murchison domain, and implications for yilgarn craton tectonicsVan Kranendonk, M.; Ivanic, T.; Wingate, M.; Kirkland, Chris; Wyche, S. (2013)Map, geochemical, and geochronological data are used to develop anewstratigraphic scheme and unravel the Archean tectonic evolution of the Murchison Domain of the Yilgarn Craton. Greenstones are divided into four groups: ...
Timing and Duration of High-Temperature Gold Mineralization and Spatially Associated Granitoid Magmatism at Chalice, Yilgarn Craton, Western AustraliaBucci, L.; McNaughton, Neal; Fletcher, Ian; Groves, D.; Kositcin, N.; Stein, H.; Hagemann, S. (2004)The Chalice gold deposit, in the Eastern Goldfields province, Yilgarn Craton, Western Australia, is located in a middle to upper amphibolite facies metamorphic domain and is hosted by a mafic-ultramafic rock sequence that ...
Structural and geochronological studies on the Liba goldfield of the West Qinling Orogen, Central ChinaZeng, Qing-Tao; McCuaig, T; Hart, Craig; Jourdan, Fred; Muhling, Janet; Bagas, Leon (2012)The Liba goldfield, located to the northeast of the Zhongchuan Granite in the West Qinling Orogen (WQO) of mainland China, contains the largest known gold resource of 2.8 Moz in the Zhongchuan area. Devonian metasedimentary ...