首页|The effect of titanite crystallisation on Eu and Ce anomalies in zircon and its implications for the assessment of porphyry Cu deposit fertility

The effect of titanite crystallisation on Eu and Ce anomalies in zircon and its implications for the assessment of porphyry Cu deposit fertility

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The redox sensitivity of Ce and Eu anomalies in zircon has been clearly demonstrated by experimental studies, and these may represent an important tool in the exploration for porphyry Cu deposits which are thought to be derived from oxidised magmas. These deposits are significant because they are the source of much of the world's copper and almost all of the molybdenum and rhenium, key elements in many modern technologies. However, Ce and Eu anomalies in zircon are also affected by the co-crystallisation of REE bearing phases, such as titanite. Here, we report the trace element chemistry of zircons from titanite-bearing intrusions associated with mineralisation at the world class Oyu Tolgoi porphyry Cu Au deposit (Mongolia). Based on these data, we suggest that neither zircon Eu/Eu*, nor Ce4+/Ce3+ are robust proxies for melt redox conditions, because they are both too strongly dependent on melt REE concentrations, which are usually poorly constrained and controlled by the crystallisation of titanite and other REE-bearing phases. In spite of this, Eu/Eu* can broadly distinguish between fertile and barren systems, so may still be an indicator of porphyry magma fertility, and a useful tool for exploration. (C) 2017 Elsevier B.V. All rights reserved.

zircontitaniteporphyry Curedoxrare earth elementseconomic geology

Loader, Matthew A.、Wilkinson, Jamie J.、Armstrong, Robin N.

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Imperial Coll London, Dept Earth Sci & Engn, Royal Sch Mines, Prince Consort Rd, London SW7 2BP, England

Nat Hist Museum, Dept Earth Sci, Cromwell Rd, London SW7 5BD, England

2017

Earth and Planetary Science Letters

Earth and Planetary Science Letters

EISCI
ISSN:0012-821X
年,卷(期):2017.472
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