The chemistry of zircon: Variations within and between large crystals from syenite and alkali basalt xenoliths

Journal Article · Fri Nov 01 00:00:00 EST 1991 · Geochimica et Cosmochimica Acta; (United States)

DOI:https://doi.org/10.1016/0016-7037(91)90489-R· OSTI ID:5171742

Hinton, R W; Upton, B G.J. ^[1]

---

1. Univ. of Edinburgh (United Kingdom)

Single grains of zircon can contain zones indicating several generations of crystal growth, each of which should reflect the chemical and physical conditions occurring at the time of its formation. Trace element analyses have been made of large zircon crystals from rocks of alkaline affinities by ion microprobe. The chondrite-normalized rare earth element (REE) concentrations increase rapidly from La to Lu, as would be expected from the decrease in ionic radius and consequent easier substitution into the Zr site within the zircon lattice. Lanthanum, praseodymium, and neodymium are considerably lower than values observed in bulk analyses of zircon. The partition coefficients for the light rare earth elements (LREEs), between zircon and melt or whole rock, must therefore be significantly lower than those calculated using bulk analyses. Cerium is enriched relative to neighboring REEs due to the presence of Ce{sup 4+}. Estimates of partition coefficients of Ce{sup 3+} and Ce{sup 4+} between zircon and melt demonstrate that although the Ce anomalies are large the Ce{sup 4+}/Ce{sup 3+} ratio is very small (less than 3 {times} 10{sup {minus}3}). The size of the Ce anomaly is variable and should be capable of providing information on oxygen fugacity changes.

• OSTI ID: 5171742
• Journal Information: Geochimica et Cosmochimica Acta; (United States), Vol. 55:11; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
RARE EARTHS
QUANTITATIVE CHEMICAL ANALYSIS
ZIRCON
BASALT
CRYSTAL GROWTH
GEOCHEMISTRY
ION MICROPROBE ANALYSIS
QUANTITY RATIO
SYENITES
CHEMICAL ANALYSIS
CHEMISTRY
ELEMENTS
IGNEOUS ROCKS
METALS
MICROANALYSIS
MINERALS
NONDESTRUCTIVE ANALYSIS
PLUTONIC ROCKS
ROCKS
SILICATE MINERALS
VOLCANIC ROCKS
580000* - Geosciences