TY - JOUR

T1 - Nodular monazite from placers in the Kular Ridge (Arctic Siberia, Russia)

T2 - Composition and age

AU - Lazareva, E. V.

AU - Zhmodik, S. M.

AU - Prokopiev, A. V.

AU - Karmanov, N. S.

AU - Sergeenko, A. I.

PY - 2018/10/1

Y1 - 2018/10/1

N2 - Nodular monazite occurs in metamorphic rocks worldwide and has zonal REE patterns. This paper focuses on the composition of nodular monazite hosted by Permian black shales of the Kular Ridge in the Kular-Nera terrane. This monazite variety (called kularite in the Russian literature) reaches commercial amounts in placers of the area. The contents of Ce, Nd, and La in the analyzed monazite nodules show correlations at Ce/Nd = 14.39La + 0.0919 (in apfu) and Ce/Nd = 0.2318La + 0.1135 (in wt.%) and vary regularly from core to rim. All monazite compositions fall on this trend, but specific grains may plot in its different parts. Thermodynamic calculations indicate that monazite forms via an intermediate precursor (LnPO4·2H2O). The Ce:La:Nd changes in different grains record Eh-pH variations during nucleation and a gradual temperature increase during subsequent growth. The Ce:La:Nd ratio changes partly in grain rims as a result of oxidative dissolution. Judging by the tectonic setting, REE came to the Kular-Nera rocks from the weathered Tomtor Nb-REE deposit, being transported by the Paleo-Khatanga River with monazite nanoparticles bound to the surface of clay minerals.

AB - Nodular monazite occurs in metamorphic rocks worldwide and has zonal REE patterns. This paper focuses on the composition of nodular monazite hosted by Permian black shales of the Kular Ridge in the Kular-Nera terrane. This monazite variety (called kularite in the Russian literature) reaches commercial amounts in placers of the area. The contents of Ce, Nd, and La in the analyzed monazite nodules show correlations at Ce/Nd = 14.39La + 0.0919 (in apfu) and Ce/Nd = 0.2318La + 0.1135 (in wt.%) and vary regularly from core to rim. All monazite compositions fall on this trend, but specific grains may plot in its different parts. Thermodynamic calculations indicate that monazite forms via an intermediate precursor (LnPO4·2H2O). The Ce:La:Nd changes in different grains record Eh-pH variations during nucleation and a gradual temperature increase during subsequent growth. The Ce:La:Nd ratio changes partly in grain rims as a result of oxidative dissolution. Judging by the tectonic setting, REE came to the Kular-Nera rocks from the weathered Tomtor Nb-REE deposit, being transported by the Paleo-Khatanga River with monazite nanoparticles bound to the surface of clay minerals.

KW - Kular Ridge

KW - nodular monazite (kularite)

KW - rare-earth elements

KW - ZIRCON

KW - MINERALS

KW - EH-PH DIAGRAMS

KW - DEPOSIT

KW - U-PB

KW - STREAM SEDIMENTS

KW - GEOCHRONOLOGY

KW - XENOTIME

KW - RARE-EARTH-ELEMENTS

KW - AUTHIGENIC MONAZITE

UR - http://www.scopus.com/inward/record.url?scp=85054927299&partnerID=8YFLogxK

U2 - 10.1016/j.rgg.2018.09.010

DO - 10.1016/j.rgg.2018.09.010

M3 - Article

AN - SCOPUS:85054927299

VL - 59

SP - 1330

EP - 1347

JO - Russian Geology and Geophysics

JF - Russian Geology and Geophysics

SN - 1068-7971

IS - 10

ER -