Petrolog

Main features of Petrolog

Petrolog4 is software for modelling fractional and equilibrium crystallisation of silicate magmas at variable pressure, melt oxidation state and melt volatile contents.

Other calculation options include modelling reverse of fractional crystallisation and modelling post-entrapment re-equilibration of melt inclusions in olivine.

Modelling of crystallisation in Petrolog4 is based on the concept of pseudo-liquidus temperatures (Nathan, Vankirk, 1978; Nielsen, Dungan, 1983; Ariskin et al., 1986). The method relies on the ability of the mineral-melt equilibrium models to calculate liquidus temperature not only for the range of melt compositions where the minerals are stable, but also for melt compositions outside the stability regions of each mineral (i.e., pseudo-liquidus temperatures).

The essence of the technique is to compare calculated pseudo-liquidus temperatures for a selected set of mineral species that may crystallize from a given melt composition. The mineral with the highest calculated temperature is considered the mineral on the liquidus of the given melt composition. This mineral is subtracted from melt, and then the process is repeated. The algorithm automatically determines the order of appearance of phases on the liquidus of the melt.

Petrolog4 offers a model-independent algorithm, which can incorporate a potentially unlimited number of phase-melt equilibrium models for major and trace elements, of solubility models for fluid components in silicate melts, of melt oxidation state models, and of models describing melt physical parameters such as density and viscosity, and other types of models.

- New feature in Petrolog4

• Modelling equilibrium between H2O-CO2 fluid and silicate melt during magma evolution;

• Modelling open and closed system degassing of H2O-CO2 fluid
  during magma evolution;

• Modelling sulphide melt - silicate melt immiscibility
  during magma evolution;

• Modelling redox equilibrium between Fe and S species
  in the silicate melt

• Modelling Fe oxidation state in the silicate melt as a function of melt composition, temperature and oxygen fugacity

• Modelling S oxidation state in silicate melt
  as a function of oxygen fugacity

• Modelling S solubility in silicate melts as sulphide and sulphate

• Modelling silicate melt recharge during magma evolution

• Modelling crystallisation of 9 silicate minerals (olivine, plagioclase, clinopyroxene, orthopyroxene, pigeonite, quartz, orthoclase,
  nepheline, leucite)

• Modelling crystallisation of 3 oxide minerals (magnetite, spinel, ilmenite)

• Incorporating corrections for the effects of the H2O content
  of the silicate melt and crystallisation pressure
  on the liquidus temperatures of silicate and oxide minerals

• Variable extent of fractionation of each phase during magma crystallisation

• Modelling trace-element distribution between silicate melt and
  other phases in the magma

  We recommend reading the manual and presentations for the full list of features

- New models in Petrolog4