TY - JOUR

T1 - Layered Nb-REE ores in the Tomtor Complex (Arctic Siberia)

T2 - 16th International Symposium on Water-Rock Interaction, WRI 2019 and 13th International Symposium on Applied Isotope Geochemistry, 1st IAGC International Conference

AU - Lazareva, Elena

AU - Zhmodik, Sergey

AU - Dobretsov, Nikolay

AU - Tolstov, Alexander

AU - Karmanov, Nikolay

AU - Dar'In, Andrey

AU - Kirichenko, Ivan

N1 - Publisher Copyright: © The Authors, published by EDP Sciences, 2019.

PY - 2019/6/7

Y1 - 2019/6/7

N2 - We study a unique deposit of Nb-REE ores that occur as three orebodies overlying weathered rocks of the Tomtor ultramafic alkaline-carbonatite complex in the northern Sakha Republic (Yakutia). The formation conditions of the rich Tomtor ores remain poorly constrained. Our hypothesis is that these ores, composed of detrital and authigenic minerals, were deposited in a hydrothermal lake. The Eh-pH parameters of water are reconstructed from REE distribution in ores and in monazite, with reference to results of thermodynamic calculations. The stability fields of hydrous Ce, La, and Nd phosphates in the Pourbaix diagrams are proximal in a region within a small range of pH (4-6) and Eh (-0.25 -+0.25 V). Monazite apparently formed by dehydration of the precursor phase of hydrous REE phosphate. This inference is supported by coexistence of Fe3+ and Fe2+ minerals.

AB - We study a unique deposit of Nb-REE ores that occur as three orebodies overlying weathered rocks of the Tomtor ultramafic alkaline-carbonatite complex in the northern Sakha Republic (Yakutia). The formation conditions of the rich Tomtor ores remain poorly constrained. Our hypothesis is that these ores, composed of detrital and authigenic minerals, were deposited in a hydrothermal lake. The Eh-pH parameters of water are reconstructed from REE distribution in ores and in monazite, with reference to results of thermodynamic calculations. The stability fields of hydrous Ce, La, and Nd phosphates in the Pourbaix diagrams are proximal in a region within a small range of pH (4-6) and Eh (-0.25 -+0.25 V). Monazite apparently formed by dehydration of the precursor phase of hydrous REE phosphate. This inference is supported by coexistence of Fe3+ and Fe2+ minerals.

KW - MINERALS

UR - http://www.scopus.com/inward/record.url?scp=85067297527&partnerID=8YFLogxK

U2 - 10.1051/e3sconf/20199805011

DO - 10.1051/e3sconf/20199805011

M3 - Conference article

AN - SCOPUS:85067297527

VL - 98

JO - E3S Web of Conferences

JF - E3S Web of Conferences

SN - 2555-0403

M1 - 05011

Y2 - 21 July 2019 through 26 July 2019

ER -