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

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216224%3A14310%2F17%3A00096233" target="_blank" >RIV/00216224:14310/17:00096233 - isvavai.cz</a>

Výsledek na webu

<a href="http://dx.doi.org/10.1016/j.oregeorev.2016.09.017" target="_blank" >http://dx.doi.org/10.1016/j.oregeorev.2016.09.017</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.oregeorev.2016.09.017" target="_blank" >10.1016/j.oregeorev.2016.09.017</a>

Jazyk výsledku

angličtina

Název v původním jazyce

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

Popis výsledku v původním jazyce

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 &gt;=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.

Název v anglickém jazyce

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

Popis výsledku anglicky

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 &gt;=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.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10500 - Earth and related environmental sciences

Projekt

—

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2017

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Ore geology reviews

ISSN

0169-1368

e-ISSN

—

Svazek periodika

80

Číslo periodika v rámci svazku

January

Stát vydavatele periodika

NL - Nizozemsko

Počet stran výsledku

20

Strana od-do

1072-1091

Kód UT WoS článku

000387625800059

EID výsledku v databázi Scopus

—