Part 2- Trace Element Modeling of Igneous Processes Flashcards Preview

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Flashcards in Part 2- Trace Element Modeling of Igneous Processes Deck (16):

What is Batch/Equilibrium melting?

Complete equilibrium between the solid phase and the melt


Give the mass balance equation for batch melting in terms of element concentrations.

Define each of the terms.

Co = CL*F + Cs (1 - F)

Co : original conc of solid(whole system)
CL : conc of liquid
Cs : conc of solid
F : Melt fraction


Define the term 'Melt Fraction' (F).

Mass of the melt divided by the mass of the system.


Give an equation for D in terms of concentrations

D = Cs / CL


How is the degree of enrichment and the degree of melting for a highly incompatible trace element related?

They are inversely proportional


What is the maximum enrichment that can be achieved for a trace element



How is fractional melting modelled?

As a case of equilibration of the solid with an infinitesimally small amount of liquid.


Give the equation for fractional melting.

What does it describe?

CL / Co = 1/D (1 - F)^^1/D - 1

The composition of a single melt increment (droplet).


How is an aggregate liquid formed?

By mixing various melt increments over the melting interval F = 0 to F


How would you calculate the composition of an aggregate liquid?

CL / Co = 1/F [1-(1-F)^^1/D]


What is equilibrium crystallisation?

When the total liquid and solid remain in equilibrium throughout crystallisation of a magma


What is the equation for equilibrium crystallisation the same as?

Identical to batch melting equation


What can the equilibrium crystallisation model be used for?

Give an example.

The equilibrium between two immiscible melts

E.g. Equilibrium between a silicate and a metallic melt during earth's core formation


What is fractional crystallisation?

An instantaneous equilibrium between liquid and an infinitesimally thin surface layer of a crystal


What is the relevant partitioning equation for fractional crystallisation?

CL / Co = F^^D-1


What affect does fractional crystallisation have on compatible element abundances in the melt?

They are dramatically and rapidly depleted.