Mineralization of the Bayan Obo Rare Earth Element Deposit by Recrystallization and Decarbonation

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F41601670%3A_____%2F22%3AN0000006" target="_blank" >RIV/41601670:_____/22:N0000006 - isvavai.cz</a>

Výsledek na webu

<a href="https://pubs.geoscienceworld.org/segweb/economicgeology/article/117/6/1327/612483/Mineralization-of-the-Bayan-Obo-Rare-Earth-Element" target="_blank" >https://pubs.geoscienceworld.org/segweb/economicgeology/article/117/6/1327/612483/Mineralization-of-the-Bayan-Obo-Rare-Earth-Element</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.5382/econgeo.4926" target="_blank" >10.5382/econgeo.4926</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Mineralization of the Bayan Obo Rare Earth Element Deposit by Recrystallization and Decarbonation

Popis výsledku v původním jazyce

The genesis of the Bayan Obo giant rare earth element (REE) deposit has been debated for several decades. Here, we report the isotopic effects of dynamic recrystallization in the H8 carbonatite, which is the principal ore carrier in the deposit. We studied fresh drill core to a depth of 1.78 km and documented the elemental and C-O-Sr isotope evolution of rock-forming dolomite during its deformation and reaction with fluids. The precursor dolomite and the products of its recrystallization differ in δ13CVienna-PeeDee Belemnite (V-PDB) (–1.09 to 2.37 vs. –3.59 to 0.79‰, respectively) and 87Sr/86Sr (0.70241–0.70394 vs. 0.70288–0.71409, respectively), and show a similar δ18Ovienna-standard mean ocean water (V-SMOW) range (10.3–16.9‰). The strong negative shift in δ13CV-PDB indicates that, locally, there was as much as 40% loss of CO2 from the precursor dolomite, although most of the recrystallized dolomite experienced decarbonation on a smaller scale. Clumped monazite grains associated with apatite in paragenetically similar samples yielded variable in situ Th-Pb dates (980–340 Ma), whereas those in monomineralic veinlets give a consistent age of ~400 Ma and consistent initial Nd isotope ratios. This indicates that the wide range of dates may not represent real REE depositional events and that the primary REE minerals deposited in the Mesoproterozoic underwent isotopic reequilibration and REE remobilization in the mid-Paleozoic. Recrystallization and decarbonation of dolomite in the H8 unit were facilitated by its reaction with subduction-derived silica- and halogen-rich fluid, genetically linked to plate-convergence processes along the northern margin of the North China craton, and did not require an influx of REEs from an external source.

Název v anglickém jazyce

Mineralization of the Bayan Obo Rare Earth Element Deposit by Recrystallization and Decarbonation

Popis výsledku anglicky

The genesis of the Bayan Obo giant rare earth element (REE) deposit has been debated for several decades. Here, we report the isotopic effects of dynamic recrystallization in the H8 carbonatite, which is the principal ore carrier in the deposit. We studied fresh drill core to a depth of 1.78 km and documented the elemental and C-O-Sr isotope evolution of rock-forming dolomite during its deformation and reaction with fluids. The precursor dolomite and the products of its recrystallization differ in δ13CVienna-PeeDee Belemnite (V-PDB) (–1.09 to 2.37 vs. –3.59 to 0.79‰, respectively) and 87Sr/86Sr (0.70241–0.70394 vs. 0.70288–0.71409, respectively), and show a similar δ18Ovienna-standard mean ocean water (V-SMOW) range (10.3–16.9‰). The strong negative shift in δ13CV-PDB indicates that, locally, there was as much as 40% loss of CO2 from the precursor dolomite, although most of the recrystallized dolomite experienced decarbonation on a smaller scale. Clumped monazite grains associated with apatite in paragenetically similar samples yielded variable in situ Th-Pb dates (980–340 Ma), whereas those in monomineralic veinlets give a consistent age of ~400 Ma and consistent initial Nd isotope ratios. This indicates that the wide range of dates may not represent real REE depositional events and that the primary REE minerals deposited in the Mesoproterozoic underwent isotopic reequilibration and REE remobilization in the mid-Paleozoic. Recrystallization and decarbonation of dolomite in the H8 unit were facilitated by its reaction with subduction-derived silica- and halogen-rich fluid, genetically linked to plate-convergence processes along the northern margin of the North China craton, and did not require an influx of REEs from an external source.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

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OECD FORD obor

10505 - Geology

Projekt

<a href="/cs/project/GX19-29124X" target="_blank" >GX19-29124X: VÝVOJ STAVEB A GEOCHEMICKÉ SIGNATURY KARBONATITŮ V ČASE: VÝZNAM MOBILITY A KONCENTRACE KRITICKÝCH KOVŮ</a><br>

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2022

Kód důvěrnosti údajů

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

Název periodika

Economic Geology

ISSN

0361-0128

e-ISSN

—

Svazek periodika

117

Číslo periodika v rámci svazku

6

Stát vydavatele periodika

US - Spojené státy americké

Počet stran výsledku

12

Strana od-do

1327-1338

Kód UT WoS článku

000827078800004

EID výsledku v databázi Scopus

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