J 2017

New insights into the origin of the Evate apatite-iron oxide-carbonate deposit, Northeastern Mozambique, constrained by mineralogy, textures, thermochronometry, and fluid inclusions

HURAI, Vratislav, Jean-Louis PAQUETTE, Monika HUIRAIOVÁ, Marek SLOBODNÍK, Pavel HVOŽĎARA et. al.

Basic information

Original name

New insights into the origin of the Evate apatite-iron oxide-carbonate deposit, Northeastern Mozambique, constrained by mineralogy, textures, thermochronometry, and fluid inclusions

Authors

HURAI, Vratislav (703 Slovakia), Jean-Louis PAQUETTE (250 France), Monika HUIRAIOVÁ (703 Slovakia), Marek SLOBODNÍK (203 Czech Republic, guarantor, belonging to the institution), Pavel HVOŽĎARA (703 Slovakia), Peter SIEGFRIED (528 Netherlands), Michaela GAJDOŠOVÁ (703 Slovakia) and Stanislava MILOVSKÁ (703 Slovakia)

Edition

Ore geology reviews, Amsterdam, ELSEVIER SCIENCE BV, 2017, 0169-1368

Other information

Language

English

Type of outcome

Článek v odborném periodiku

Field of Study

10500 1.5. Earth and related environmental sciences

Country of publisher

Netherlands

Confidentiality degree

není předmětem státního či obchodního tajemství

References:

Impact factor

Impact factor: 3.993

RIV identification code

RIV/00216224:14310/17:00096233

Organization unit

Faculty of Science

DOI

UT WoS

000387625800059

Keywords in English

Carbonatite; Apatite; East-African orogen; U-Th-Pb dating; Fluid inclusions; Evate deposit

Tags

Tags

International impact, Reviewed
Změněno: 9/4/2018 16:20, Ing. Nicole Zrilić

Abstract

V originále

The Evate deposit represents the largest resource of apatite in south-east Africa (155 Mt. ore grading 9.3 wt.% P2O5) accumulated in up to 100 m thick magnetite-carbonate-apatite horizons conformable to the granulitic gneiss of the Monapo Klippe. Baddeleyite and zircon from early iron-oxide (magnetite, geikielite, spinel), apatite- and forsterite-bearing rocks have been dated to 590±6 Ma using the LA-ICPMS U-Pb method, whereas monazites from anhydrite-apatite-carbonate rocks show a concordant U-Pb-Th age corresponding to 449 ± 2 Ma. Temperatures inferred fromcalcite-dolomite solvus data and graphite structural ordering span the interval from >=815 to 276 °C. Primary and secondary fluid inclusions in apatite document calciocarbonatite melts associated with early apatite, and CO2-bearing sulfate-chloride brines progressively dilutedwith low-salinity, probably meteoric waters, towards ultimate stages of the deposit formation. The calciocarbonatite melts have initially coexisted with liquid nitrogen and later with sulfate-chloride brines mixed with N2± CO2 gas. Crystallization of spinel around baddeleyite by the mechanismof Ostwald ripening, nucleation of graphite spherules along pyrrhotite-carbonate boundaries, the occurrence of molybdenite, baddeleyite-to-zircon transformation, and high crystallization temperatures inferred from graphite structural ordering and calcite-dolomite thermometry suggest a magmatic origin of the early mineral assemblages. In contrast, microthermometric characteristics of primary aqueous inclusions in the late apatite and the presence of zeolites (thomsonite-Ca, mezolite) is diagnostic of a low-temperature hydrothermal crystallization. Formation of the early magnetite-apatite-forsterite assemblage is thought to be coeval with mafic alkalic intrusions of the Mazerapane Suite superimposed on the granulite facies metamorphism of the Monapo Klippe. The low-temperature, anhydrite-bearing mineralization was associated with the massive circulation of sulfate-rich brines along fractures activated during the Late Cambrian-Ordovician extension. Origin of the sulfate-rich brines may be genetically related either with the magmatic-hydrothermal differentiation, or with the remobilization of crustal evaporites.