Application of lanthanides tetrad effect as a geochemical indicator to identify fluorite generations: A case study from the Laal-Kan fluorite deposit, NW Iran

Abstract

The Laal-Kan fluorite deposit situated in north margin of the Sanandaj-Sirjan metamorphic belt and Urmia-Dokhtar magmatic arc, NW Iran. The fluorite mineralization in the form of open-space filling, veins and veinlets have been deposited in the contact zone between highly metamorphosed schist, gneiss, amphibolite of the Paleozoic age and the Jangutaran limestone of the Precambrian age. The occurrence of convex tetrad effect and the calculated tetrad values indicate that early and late stage fluorite mineralization display various geochemical behavior, which are supported by the bivariate diagrams including T 1 , T 3 and T 4 versus each other and some geochemical parameters such as La/Ho, Y/Ho and Zr/Hf ratios. It can, therefore, deduced that fluorite have been probably formed during two stages from hydrothermal fluids with a relatively constant composition. The fluid-rock interaction during deposition of fluorite and REE-F complex were likely the main mechanisms for the occurrence of tetrad effect.

Gadolinium-dominant monazite and xenotime: Selective hydrothermal enrichment of middle REE during low-temperature alteration of uraninite, brannerite, and fluorapatite (the Zimná Voda REE-U-Au quartz vein, Western Carpathians, Slovakia)

“…American Mineralogist, in press. , which is dependent mainly on charge and ionic radiuscontrolled behavior (CHARAC)(Bau 1996;Rezaei Azizi et al 2017). Selective enrichment of Gd or other individual MREE and HREE in terms of absolute abundances is a rare process and does not appear to be related to specific lithologies and environments (cf Demartin et al 1993…”

Quantifying the Tetrad Effect, Shape Components, and Ce–Eu–Gd Anomalies in Rare Earth Element Patterns

“…The fractionation can be positive or negative, which is manifested as a series of ridges or troughs on a REE pattern, occasionally called M-type and W-type, respectively. Various combinations of these types can also be observed (Azizi et al 2020). The tetrad effect stems from quantum mechanical effects on the electronic structure and energies of the 4f subshell (Kawabe 1992).…”

Lanthanide tetrad effects in stream sediment rich- gold of Betare Oya area (Cameroon Pan-African fold belt, Betare Oya gold district): implication for REE- bearing phases fractionation

“…Each curve consists of four segments (La-Ce-Pr-Nd, Pm-Sm-Eu-Gd, Gd-Tb-Dy-Ho, Er-Tb-Yb-Lu) called rst, second, third and fourth tetrads respectively. The middle two elements of each tetrad are fractionated relative to the elements at the edges; this fractionation can be positive or negative, combinations are also possible (Azizi et al, 2020).…”

“…The rounded segments are convex or concave and form M-shaped and W-shaped lanthanide distribution patterns, respectively (Azizi et al, 2020;Masuda et al, 1989). M-and W-types tetrad effects point to the opposite behavior of lanthanides at the tetrad boundaries (Masuda et al, 1989;Chen et al, 2020) ie Nd between the rst and the second tetrads, Gd between the second and the third.…”