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The bimodal fluid evolution of the Nimbus Zn-Ag deposit: an Archean VHMS with epithermal characteristics
Caruso, Stefano; Fiorentini, Marco L.; LaFlamme, Crystal; Hollis, Steven P.; et al.
SGA Quebec 2017, Quebec City, Canada, 20-23 August 2017 The Nimbus Zn-Ag VHMS deposit represents an exceptional mineralised occurrence in the Yilgarn Craton. While other VHMS systems in the craton are restricted to paleo-rift zones, Nimbus is associated to a plume-related stratigraphy (Hollis et al., 2017). Furthermore, the epithermal characteristics resulting from low temperature and shallow water conditions allowed the development of an unusual mineralisation dominated by Ag-rich sulfosalts. In this study we take advantage of state-of-the-art in-situ techniques to investigate the fluid evolution of this peculiar VHMS system. From the trace element compositions and S-isotope signatures we suggest that Nimbus experienced a bimodal fluid evolution consisting of (i) an initial intense interaction between deep-magmatic fluids and seawater that developed barren pyritic lenses, and (ii) a subsequent closure of the hydrothermal system during which the Agrich ore formed sourcing sulfur almost entirely from a deepmagmatic source.
Keyword(s): Bimodal fluid evolution; Volcanic-hosted massive sulfide; Nimbus
Publication Date:
2018
Type: Other
Peer-Reviewed: Unknown
Language(s): English
Institution: University College Dublin
Publisher(s): Society for Geology Applied to Mineral Deposits
First Indexed: 2019-05-11 06:34:50 Last Updated: 2019-05-11 06:34:50