Publication detail

Development of REE mineralization in the giant Maoniuping deposit (Sichuan, China): insights from mineralogy, fluid inclusions, and trace-element geochemistry

LIU, Y. CHAKHMOURADIAN, A. HOU, ZQ. SONG, W. KYNICKÝ, J.

Original Title

Development of REE mineralization in the giant Maoniuping deposit (Sichuan, China): insights from mineralogy, fluid inclusions, and trace-element geochemistry

Type

journal article in Web of Science

Language

English

Original Abstract

Rare-earth deposits associated with intrusive carbonatite complexes are the world's most important source of these elements (REE). One of the largest deposits of this type is Maoniuping in the Mianning-Dechang metallogenic belt of eastern Tibet (Sichuan, China). In the currently mined central part of the deposit (Dagudao section), REE mineralization is hosted by a structurally and mineralogically complex Late Oligocene (26.4 +/- 1.2Ma, Ar-40/Ar-39 age of fluorphlogopite associated with bastnasite) hydrothermal vein system developed in a coeval syenite intrusion. Low-grade stockworks of multiple veinlets and breccias in the lower part of the orebody grade upwards into progressively thicker veins (up to 12m in width) that are typically zoned and comprise ferromagnesian micas (biotite to fluorphlogopite), sodium clinopyroxenes (aegirine to aegirine-augite), sodium amphiboles (magnesio-arfvedsonite to fluororichterite), K-feldspar, fluorite, barite, calcite, and bastnasite. The latter four minerals are most common in the uppermost 80m of the Dagudao section and represent the climax of hydrothermal activity. Systematic variations in the fluid inclusion data indicate a continuous hydrothermal evolution from about 230-400 degrees C (fluid inclusions in feldspar, clinopyroxene, and amphibole) to 140-240 degrees C (fluid inclusions in bastnasite, fluorite, calcite). Hydrothermal REE transport was probably controlled by F-, (SO4)(2-), Cl-, and (CO3)(2-) as complexing ligands. We propose that at Dagudao, silicate magmas produced orthomagmatic fluids that explored and expanded a fissure system generated by strike-slip faulting. Initially, the fluids had appreciable capacity to transport REE and, consequently, no major mineralization developed. The earliest minerals to precipitate were alkali- and Fe-rich silicates containing low levels of F, which caused progressive enrichment of the fluid in Ca, Mg, F, Cl, REE, (SO4)(2-), and (CO3)(2-), leading to the crystallization of aegirine-augite, fluororichterite, fluorphlogopite, fluorite, barite, calcite, and bastnasite gradually. Barite, fluorite, calcite, and bastnasite are the most common minerals in typical ores, and bastnasite generally postdates these gangue minerals. Thus, it is very probable that fluid cooling and formation of large amount of fluorite, barite, and calcite triggered bastnasite precipitation in the waning stage of hydrothermal activity.

Keywords

Maoniuping deposit; Mianning-Dechang metallogenic belt; REE mineralization; Carbonatite-syenite complex; Mineral compositions; Fluid inclusions; Ar-Ar age

Authors

LIU, Y.; CHAKHMOURADIAN, A.; HOU, ZQ.; SONG, W.; KYNICKÝ, J.

Released

30. 6. 2019

ISBN

0026-4598

Periodical

MINERALIUM DEPOSITA

Year of study

54

Number

5

State

Federal Republic of Germany

Pages from

701

Pages to

718

Pages count

18

URL

https://doi.org/10.1007/s00126-018-0836-y

BibTex

@article{BUT163420,
  author="LIU, Y. and CHAKHMOURADIAN, A. and HOU, ZQ. and SONG, W. and KYNICKÝ, J.",
  title="Development of REE mineralization in the giant Maoniuping deposit (Sichuan, China): insights from mineralogy, fluid inclusions, and trace-element geochemistry
",
  journal="MINERALIUM DEPOSITA",
  year="2019",
  volume="54",
  number="5",
  pages="701--718",
  doi="10.1007/s00126-018-0836-y",
  issn="0026-4598",
  url="https://doi.org/10.1007/s00126-018-0836-y"
}