Non-chondritic yttrium/holmium ratio and lanthanide tetrad effect observed in pre-Cenozoic limestones.

Abstract

REE and Y in limestones have been determined by ICP-AES method coupled with pre-concentra tion chemical procedures. The lanthanide tetrad effect has been clearly observed in the REE patterns of two Permian limestones. It is the W-type tetrad effect seen in seawaters. Y/Ho ratios for the limestones show large positive deviations from the chondritic ratio. Similar non-chondritic Y / Ho ratios are seen in a Precambrian limestone from South Africa, seawaters, and marine phosphorites. Their REE patterns are well characterized by the W-type tetrad effect. These facts and recent results of aquatic geochemistry of REE and Y strongly suggest that the positive Y anomalies are intimately associated with the W-type tetrad effect of REE in natural aquatic solutions including seawaters and in some hydrogenous deposits from the solutions. Y is not a pseudo lanthanide that behaves like Ho in natural conditions where the lanthanide tetrad effect is operative. This must be a thermochemical effect related to the absence of 4f electron in Y3+ and the systematic differences in 4f electronic configurations in the REE3+ series. The REE plus Y patterns with positive Y anomalies and the W-type tetrad effect are important for the gochemical studies of limestones and other hydrogeneous deposits.

Characteristics of rare earth element abundances in shallow marine continental platform carbonates of Late Neoproterozoic successions from India.

“…The similarity of Y with Ho in ionic size and Kawabe et al (1991) recognized that marine carbonates display nonchondritic Y/Ho ratios (i.e., Y/Ho > 27). Later studies on REE and Y abundances in marine realm by Bau et al (1995) and Nozaki et al (1997) showed superchondritic Y/Ho ratios in sea water.…”

“…Analytical uncertainties arẽ 5% or less. Detailed analytical method for extractions of REE and Y from carbonate matrix is given in Kawabe et al (1991Kawabe et al ( , 1994.…”

Partitioning of rare earth and high field strength elements between titanite and phonolitic liquid

“…5); the effect appears to become negligible at about 1200°C. This in turn suggests the possible use of Y/Ho ratios as a geochemical tracer of low-temperature melting (below ~1100°C) processes in petrogenesis and magma source history; however, incorporation of sediment into magma sources could have similar effects due to the strong fractionation of Y from Ho in the marine environment (Kawabe et al, 1991;Nozaki et al, 1997).…”

Dolomitization of linrestone with MgCl2 solution at 150.DEG.C.. Preserved original signatures of rare earth elements and yttrium as marine limestone.

“…The REE and Y pattern has a concave tetrad effect, a large negative Ce anomaly, a small negative Eu anomaly and a high Y/Ho ratio. These are the typical characteristics of REE and Y patterns for marine limestones (Kawabe et al, 1991;Miura et al, 1999).…”

“…Each run product was dissolved in HCl. The REE and Y in the solution were separated from matrix elements by the method of coprecipitation with Fe(III) oxyhydroxide and cation-exchange chromatography described elsewhere (Kawabe et al, 1991(Kawabe et al, , 1994. Finally they were analyzed by ICP atomic emission spectrometry (ICP-AES) and ICP mass spectrometry (ICP-MS).…”