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147612_Staged formation of the supergiant Olympic Dam uranium deposit, Australia.pdf (2.09 MB)

Staged formation of the supergiant Olympic Dam uranium deposit, Australia

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posted on 2023-05-21, 03:55 authored by Kathy EhrigKathy Ehrig, Vadim Kamenetsky, Jocelyn McPhieJocelyn McPhie, Macmillan, E, Thompson, J, Maya KamenetskyMaya Kamenetsky, Mass, R
The origins of many supergiant ore deposits remain unresolved because the factors responsible for such extreme metal enrichments are not understood. One factor of critical importance is the timing of mineralization. However, timing information is commonly confounded by the difficulty of dating ore minerals. The world's largest uranium resource at Olympic Dam, South Australia, is exceptional because the high abundance of U allows U-Pb dating of ore minerals. The Olympic Dam U(-Cu-Au-Ag) ore deposit is hosted in ca. 1.59 Ga rocks, and the consensus has been that the supergiant deposit formed at the same time. We argue that, in fact, two stages of mineralization were involved. Paired in situ U-Pb and trace element analyses of texturally distinct uraninite populations show that the supergiant size and highest-U-grade zones are the result of U addition at 0.7–0.5 Ga, at least one billion years after initial formation. This conclusion is supported by a remarkable clustering of thousands of radiogenic 207Pb/206Pb model ages of Cu sulfide grains at this time. Upgrading of the original ca. 1.59 Ga U deposit to its present size at 0.7–0.5 Ga may have resulted from perturbation of regional fluid flow triggered by global climatic (deglaciation) and tectonic (breakup of Rodinia) events.

Funding

Australian Research Council

BHP Billiton Olympic Dam Corporation

History

Publication title

Geology

Volume

49

Issue

11

Pagination

1312-1316

ISSN

0091-7613

Department/School

School of Natural Sciences

Publisher

Geological Soc America

Place of publication

Inc, Po Box 9140, Boulder, USA, Co, 80301-9140

Rights statement

© 2021 The Authors. Gold Open Access: This paper is published under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) license. (https://creativecommons.org/licenses/by-nc/4.0/)

Repository Status

  • Open

Socio-economic Objectives

Expanding knowledge in the earth sciences

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