parental magma

parental magma

[pə′rent·əl ′mag·mə]
(geology)
The naturally occurring mobile rock material from which a particular igneous rock solidified or from which another magma was derived.
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Around the Montepuez Belt, ruby formations seem to have resulted mainly from a metasomatic process, when fluid derived from the parental magma interacted with the host rocks in a low-silica environment.
Parental magma likely comprised a plagioclase-phyric basaltic melt, containing ~15-45 vol% plagioclase phenocrysts.
Fiskenoesset, Bad Vermillion Lake), for example, likely formed through flotation of plagioclase phenocrysts during in situ fractional crystallization of basaltic parental magma (Windley et al.
2007), it follows that the parental magma to the pluton had a crystal to melt ratio around ~45:55.
Furthermore, the estimated ~45:55 crystal to melt ratio of the parental magma lies well above the ~35:65 ratio required to form rigid crystal frameworks, suggesting that plagioclase crystal frameworks formed shortly after magma emplacement.
The bulk composition of the Marginal Zone (~74% plagioclase and ~26% pyroxene plus accessory minerals) suggests that the crystal to melt ratio of parental magma was only ~15:85, well below the ~35:65 threshold for developing crystal frameworks.
Just as important is that these processes are consistent with the crystallization of a viscous plagioclase-phyric parental magma.
Since then, no attempt has been made to integrate the field characteristics with the newer petrogenetic models for massif-type anorthosite, leaving some uncertainty in regards to how viscous plagioclase-phyric parental magmas could have crystallized under apparently dynamic conditions.
Using the earliest rock type (diabase porphyry) as a parental magma, it is likely that evolution of rock compositions was produced by crystallization of plagioclase and clinopyroxene.
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