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A model for carbonatite hosted REE mineralisation — the Mianning–Dechang REE belt, Western Sichuan Province, China

journal contribution
posted on 2023-05-18, 07:33 authored by Xie, Y, Li, Y, Hou, Z, David CookeDavid Cooke, Leonid Danyushevsky, Dominy, SC, Yin, S
The Mianning–Dechang (MD) REE belt of Sichuan, China is one of the most important REE belt in China, which includes Maoniuping, the third largest REE deposit in the world and a series of large to small REE deposits. Mineralization styles varied across the belt, as well as within different parts of the same deposit. Styles include vein-stockworks, pegmatites, breccias and disseminated REE mineralization. Based on geological, geochemical and inclusion studies, this paper proposes a new model for carbonatite hosted REE mineralization. The results show that ore-forming fluid is derived from carbonatite magma, which has high temperature, pressure and density, and is characterized by high K, Na, Ca, Sr, Ba, REE and SO4 contents. The supercritical ore fluid underwent a distinctive evolution path including phase separation, exolution of sulfate melt and unmixing between aqueous fluid and liquid CO2. Rapid geochemical evolution of a dense carbonatite fluid causes REE mineralization and associated alteration to occur within or proximal to the source carbonatite. Veins, pegmatites and carbonatite comprise a continuum of mineralization styles. Veins occur in the outer zone of the upper levels of the deposit. Pegmatites occur in the inner zone of upper levels, whereas disseminated REE ore occurs at the base of the carbonatite. High water solubility in the carbonatite magma and low water, high REE in the exsolved ore-forming fluids, imply that a giant carbonatite body and deep magma chamber are not necessary for the formation of giant REE deposits.

Funding

Australian Research Council

AMIRA International Ltd

ARC C of E Industry Partner $ to be allocated

Anglo American Exploration Philippines Inc

AngloGold Ashanti Australia Limited

Australian National University

BHP Billiton Ltd

Barrick (Australia Pacific) PTY Limited

CSIRO Earth Science & Resource Engineering

Mineral Resources Tasmania

Minerals Council of Australia

Newcrest Mining Limited

Newmont Australia Ltd

Oz Minerals Australia Limited

Rio Tinto Exploration

St Barbara Limited

Teck Cominco Limited

University of Melbourne

University of Queensland

Zinifex Australia Ltd

History

Publication title

Ore Geology Reviews

Volume

70

Pagination

595-612

ISSN

0169-1368

Department/School

School of Natural Sciences

Publisher

Elsevier Science Bv

Place of publication

Po Box 211, Amsterdam, Netherlands, 1000 Ae

Rights statement

© 2014 Elsevier

Repository Status

  • Restricted

Socio-economic Objectives

Titanium minerals, zircon, and rare earth metal ore (e.g. monazite) exploration

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