J 2021

Thermobarometric and geochronologic constraints on the emplacement of the Neoproterozoic Evate carbonatite during exhumation of the Monapo granulite complex, Mozambique

HURAI, Vratislav, Michaela BLAŽEKOVÁ, Monika HURAIOVÁ, Pete R. SIEGFRIED, Marek SLOBODNÍK et. al.

Základní údaje

Originální název

Thermobarometric and geochronologic constraints on the emplacement of the Neoproterozoic Evate carbonatite during exhumation of the Monapo granulite complex, Mozambique

Autoři

HURAI, Vratislav, Michaela BLAŽEKOVÁ, Monika HURAIOVÁ, Pete R. SIEGFRIED, Marek SLOBODNÍK (203 Česká republika, garant, domácí) a Patrik KONEČNÝ

Vydání

Lithos, Amsterdam, Elsevier, 2021, 0024-4937

Další údaje

Jazyk

angličtina

Typ výsledku

Článek v odborném periodiku

Obor

10500 1.5. Earth and related environmental sciences

Stát vydavatele

Nizozemské království

Utajení

není předmětem státního či obchodního tajemství

Odkazy

Impakt faktor

Impact factor: 4.020

Kód RIV

RIV/00216224:14310/21:00120879

Organizační jednotka

Přírodovědecká fakulta

UT WoS

000612255400005

Klíčová slova anglicky

Carbonatite; Fenite; Fluid inclusions; Granulite; Thermobarometry; Geochronology

Štítky

Příznaky

Mezinárodní význam, Recenzováno
Změněno: 14. 7. 2021 13:21, doc. RNDr. Marek Slobodník, CSc.

Anotace

V originále

Fluid inclusion and mineral thermobarometric study supplemented by U-Th-total Pb monazite dating has been carried out in country rocks of the Evate carbonatite, which is an example of a Neoproterozoic (-590 Ma) orogenic carbonatite formed within a post-collisional tectonic setting in the Monapo granulite complex of NE Mozambique. The fluid inclusion analysis of a 573 +/- 13 Ma old fenite subjacent to the Evate carbonatite revealed primary, high-density to superdense CO2-rich fluids (1 g.cm(-3)) with minor admixtures of N-2 (0-17.5 mol%) and CH4 (0-1.1 mol%) accompanied by alkalic hydrocarbonate melts and aqueous fluids with minor sulphates. Isochores of CO2 inclusions intersected by isopleths calculated from Ti-in-quartz and Zr-in-rutile thermometers indicate fenite formation at 480-530 degrees C and 2.1-5.4 kbar. The CO2-rich gas of the fenite-forming fluids/melts is similar to the anhydrous CO2 gas with traces of N-2 (<1.5 mol%) trapped in granulites and paragneisses of the Monapo Complex during granulite-facies metamorphism (similar to 850 degrees C, similar to 9 kbar) and superimposed retrogression under amphibolite-facies conditions (similar to 550 degrees C, similar to 5 kbar) within the time interval between 680 and 590 Ma (Cryogenian to Ediacaran). Peak metamorphic conditions within the Monapo Complex are diagnostic of a hot orogen similar to that in other Pan-African Neoproterozoic HT/UHT granulite terranes. The exhumation PT trajectory of the Monapo Complex diverted from a "near-isochoric"-shaped curve to near-isothermal (similar to 500 degrees C) decompression at similar to 590 Ma coeval with the intrusion of the Evate carbonatite into the disrupted continental crust. The pressure fluctuations during the concomitant fenitization were reflected in densities of carbonic inclusions, ranging between 1.178 and 0.773 g.cm(-3). Secondary, low-density N-2-rich inclusions (82-99 mol% N-2, 0.8-13.7 mol% CH4, 0-4.5 mol% CO2) homogenized to vapour at temperatures below -173 degrees C recorded the fenite cataclasis at temperatures below 400 degrees C and very low pressures. The probable maximum burial depth of the Evate carbonatite, similar to 20 km, is estimated from the maximum fluid pressure of 5.4 kbar attributed to lithostatic load of the crust with an average density of 2.75 g.cm(-3).