Mantle heat drives hydrothermal fluids responsible for carbonate-hosted base metal deposits: evidence from 3He/4He of ore fluids in the Irish Pb-Zn ore district

Davidheiser-Kroll, B., Stuart, F. M. and Boyce, A. J. (2014) Mantle heat drives hydrothermal fluids responsible for carbonate-hosted base metal deposits: evidence from 3He/4He of ore fluids in the Irish Pb-Zn ore district. Mineralium Deposita, 49(5), pp. 547-553. (doi:10.1007/s00126-014-0516-5)

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Abstract

There is little consensus on whether carbonate-hosted base metal deposits, such as the world-class Irish Zn+Pb ore field, formed in collisional or extensional tectonic settings. Helium isotopes have been analysed in ore fluids trapped in sulphides samples from the major base metal deposits of the Irish Zn-Pb ore field in order to quantify the involvement of mantle-derived volatiles, that require melting to be realised, as well as test prevailing models for the genesis of the ore fields. 3He/4He ratios range up to 0.2 Ra, indicating that a small but clear mantle helium contribution is present in the mineralising fluids trapped in galena and marcasite. Sulfides from ore deposits with the highest fluid inclusion temperatures (~200°C) also have the highest 3He/4He (> 0.15 Ra). Similar 3He/4He are recorded in fluids from modern continental regions that are undergoing active extension. By analogy we consider that the hydrothermal fluids responsible for the carbonate-hosted Irish base metal mineralization circulated in thinned continental crust, undergoing extension, and demonstrates that enhanced mantle heat flow is ultimately responsible for driving fluid convection.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Boyce, Professor Adrian and Stuart, Professor Finlay
Authors: Davidheiser-Kroll, B., Stuart, F. M., and Boyce, A. J.
College/School:College of Science and Engineering > Scottish Universities Environmental Research Centre
Journal Name:Mineralium Deposita
Publisher:Springer
ISSN:0026-4598
ISSN (Online):1432-1866
Copyright Holders:Copyright © 2014 Springer-Verlag Berlin Heidelberg
First Published:First published in Mineralium Deposita 49(5):547-553
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher

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