Zircon trace elements

Rubatto D. (2002) Zircon trace element geochemistry partitioning with garnet and the link between U—Pb ages and metamorphism. Chem. Geol. 184, 123—138. 

Thomas JB, Bodnar RJ, Shimizu N, Sinha AK (2002) Determination of zircon/melt trace element partition coefficients from SIMS analysis of melt inclusions in zircon. Geochim Cosmochim Acta 66 2887-2901 Thompson GM, Malpas J (2000) Mineral/melt partition coefficients of oceanic alkali basalts determined on natural samples using laser ablation-inductively eouple plasma-mass spectrometry (LAM-ICP-MS). Mineral Mag 64 85-94... 

Behavior of trace element that can be treated as effective binary diffusion The above discussion is for the behavior of the principal equilibrium-determining component. For minor and trace elements, there are at least two complexities. One is the multicomponent effect, which often results in uphill diffusion. This is because the cross-terms may dominate the diffusion behavior of such components. The second complexity is that the interface-melt concentration is not fixed by thermodynamic equilibrium. For example, for zircon growth, Zr concentration in the interface-melt is roughly the equilibrium concentration (or zircon saturation concentration). However, for Pb, the concentration would not be fixed. 

Since oil shale is fine-grained and typically does not contain any trace element-loaded minor minerals such as allanite or zircon, inhomogeneity of the pulverized sample is not likely. Table II shows analytical results for rubidium and strontium on different 0.500-g splits (16) and 300-/xg replicates (21), For most of the elements studied, homogeneity is retained down to the SOO-fig sample sizes. 

Types of analyses PI = fluid inclusions, ME = major element analyses Min = mineral analyses TE = trace element analyses Sr = Sr isotope analyses Nd = Nd isotope analyses Pb = Pb isotope analyses, O = oxygen isotope analyses, C = carbon isotope analyses, U-Pb = U-Pb geochronology on accessory phases (zircon, rutile, titanite, etc.). 

Accessory minerals commonly contain high concentrations of radioactive elements, and are a common target of radiogenic isotope measurements. Specific elements include uranium (zircon, apatite, titanite, monazite, xenotime, allanite) and thorium (monazite and allanite). Each accessory mineral is stabilized in a rock via a single element or suite of related elements, specifically phosphorous (apatite), REE (allanite, monazite, xenotime), zirconium (zircon), and titanium (titanite). Trace elements also occur in the major minerals (particularly phosphorous, zirconium, and titanium), so accessory minerals participate directly in major mineral reactions (Pyle and Spear, 1999, 2000, 2003 Ferry, 2000 Pyle et al, 2001 ... 

A number of models for the very early Earth propose the existence of a Hadean (ca. 4.5 Ga) basaltic crust. The evidence for such a model comes from the study of 142Nd and is consistent with the observed extreme fractionation of 207Pb (Kamber et al., 2003), and with Hf-isotope studies on zircons (Bizzarro et al., 2003). For this reason it has been proposed that an early, trace element enriched mafic crust, created perhaps as a lid to a Hadean magma ocean, was subducted and buried deep in the mantle, where it is thought to be still stored (Galer Goldstein, 1988, 1991). Hence, this material is a candidate for a lower mantle layer and is another possible explanation for a layered mantle created very early in Earth history. 

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Murray RW, Tenbrink MRB, Gerlach DC Russ GP Jones DL (1992) Interoceanic variation in the rare-earth, major, and trace-element depositional chemistry of chert—perspectives gained from the DSDP and ODP record. Geochim Cosmochim Acta 56 1897-1913 Nagasawa H (1970) Rare earth concentrations in zircons and apatites and their host dacites. Earth Planet Sci Lett 9 359-364... 

Maas Rh md McCulloch M.T., 1991, The provenance of Archaean clastic metasediments in the Nartyer Gneiss Complex, western Australia trace element geochemistry, Nd isotopes and U-Pb ages for detrital zircons. Geochim. Cosmochtm. Acta, 55, 1915—1932. McConnaughey T., 1989, C and isotopic disequilibrium in biological carbonates 1. 

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