TEXTURAL AND MICROANALYSIS OF IGNEOUS ROCKS: TOOLS ...

(i.e., using textural, seismic, or other geophysical data) data. Magma chamber
architecture has a profound influence on the chemistry of evolving magmas [98].
Geochemists customarily envisage magma chambers as large vats of magma, where
processes such as fractional crystallization, magma mixing, and assimilation are
modeled within a physically simple context (e.g., Fig. 1.1a). For example, Fig-
ure 1.1a, from Sano and Yamashita [123], illustrates a relatively simple magma
chamber model for the Ontong Java Plateau (OJP) based only upon geochemical
data and petrographic observations. The magma chamber system of Kilauea vol-
cano, Hawaii is depicted much differently as a complicated interconnected network
of dikes, sills, and chambers [122]. This Kilauea model was constructed using seis-
mic data by Ryan [122] (Fig. 1.1b). Neither model is necessarily ill-constructed,
but each model was contrived to explain either physical observations or chemical
observations but not both. Chemical and physical magma chamber models must
be better integrated in order to generate more realistic (and accurate) models
of magma chamber architecture and how this architecture is related to magma
dynamics and the chemical evolution of magma.
1.2.1 Magma Chamber Processes: How Do Magmas Evolve?
Magma chamber processes such as partial crystallization, magma mixing, and/or
assimilation play a controlling role in shallow level differentiation and need to be
understood if a parental (or even primary) magma compositions are to be es-
timated. Magma chamber architecture influences the physical manner in which
differentiation processes occur (i.e., homogenous crystallization vs. solidification
front crystallization)[97]. The role of solidification fronts, crystal-mush piles, and
their interstitial liquids have increasingly recognized roles in magmatic differen-
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