Melting models

Pickett et al. 1997) in MORE samples played an important role, not only to address the problem of magma transfer times, but also in the development of dynamic melting models able to sustain such disequilibria over long periods. In subduction zone volcanoes, the combined study of and Ra- °Th disequilibria place unique constraints on the... 

Figure 6. The tree of models showing the relationships and differences between various U-series melting models.

Iwamori H (1993) Dynamic disequilibrium melting model with porous flow and diffusion-controlled chemical equilibration. Earth Planet Sci Lett 114 301-313 Iwamori H (1994) U- °Th- Ra and Pa disequihbria produced by mantle melting with porous and channel flows. Earth Planet Sci Lett 125 1-16... 

As explained below, most melting models are highly sensitive to the D values chosen for the parent elements U and Th. For example, in the case of simple batch melting, it can be shown that the U- Pa fractionation will only depend on the partition coefficients for U as long as Dpa is essentially zero ... 

Time dependent melting models for hotspot magmatism... 

Table 1. Main parameters used in melting models.

Dynamic melting models provide results that are similar to those obtained from the chromatographic porous flow melting model in that the extent of ( Ra/ Th)... 

While over the past ten years, our ability to measure U-series disequilibria and interpret this data has improved significantly it is important to note that many questions still remain. In particular, because of uncertainties in the partition coefficients, fully quantitative constraints can only be obtained when more experimental data, as a function of P and T as well as source composition, become available. Furthermore, the robustness of the various melting models that are used to interpret the data needs to be established and 2D and 3D models need to be developed. However, full testing of these models will only be possible when more comprehensive data sets including all the geochemical parameters are available for more locations and settings. 

ANALYTICAL SOLUTIONS FOR TIME DEPENDENT MELTING MODELS... 

Batch and equilibrium porous flow melting models... 

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