Experimental and observational evidence suggest that olivine, followed by clinopyroxene and plagioclase, are the earliest crystallizing phases from mafic magma
A late influx of mafic magma
disrupted older mafic rocks and hybridised with granite, producing complex, heterogeneous "diorite".
The Tertiary Capitan dike swarm appears to represent the emanations from a crystallizing and differentiating mafic magma
chamber or chambers that were episodically replenished by influxes of basaltic magma.
Arcs under extension have a steep geothermal gradient and underplating of the crust by mafic magma
may transfer sufficient heat to induce anatexis.
A likely model is that a mafic magma
(possibly mantle derived) of the MPS was emplaced first and underwent substantial crystal fractionation to produce the mafic and ultramafic St.
Hybrids dominated by the crustal melts are expressed by the various facies of the Monte Capanne pluton, whereas the mafic magma
hybrids are represented by the ubiquitous presence of a wide variety of mafic microgranular enclaves.
In these "fossil", high-level magma chambers, such as the Pleasant Bay Complex (Wiebe 1993a), field relations indicate that mafic magma
was episodically injected into the crystallizing felsic magma chamber.
39] studies of these rocks record episodic deformation and varying degrees of metamorphism up to lower amphibolite facies, and a protracted history of mafic magma
injection from a similar source beginning in the Early Silurian.
The PLI mineralized sequences record the introduction of discrete sulphide- and fragment-bearing magma pulses into evolving, dynamic, mafic magma
chambers, as suggested for the Voisey's Bay deposit.
Similarly, Ba behaves incompatibly in mafic magmas
but concentrations either level off of fall in highly differentiated rocks.
Each process produces voluminous mafic magmas
, but on different and independent time scales and with different characteristic plan forms.
1998), we favour a westward subduction model generating the mafic magmas
of the New Hampshire Plutonic Suite and Merrimack belt with transpressive extension to account for the Rochester/Hardwick plutons.