The extreme case of this process is episyenitization, a natural postmagmatic
process resulting in episyenite formation (Hecht, 1999; Petersson and Eliasson, 1997).
However, we suggest that the skarn-type mineralogy hosted in this metamorphic unit should be related both magmatic and postmagmatic
stages of the Santa Martha Batholith, and is the result of a very complex skarn-type mineralogy zonation (Castellanos and co-workers, personal communication).
mineral deposits of the northern edge of the Bohemian massif (Erzgebirge-Harz), Central Geological Institute GDR.
Since the pyroclastic material is prone to hydration and other postmagmatic
alterations affecting predominantly the alkali contents, the classification was further confirmed in the diagram of Winchester & Floyd (1977; Fig.
The upper part of the lava flow became vesicular and scoriaceous due to lava degassing, and strongly affected by postmagmatic zeolitization evidencing volatile-phase activity after the eruption.
Owing to the activity of postmagmatic hydrothermal fluids, a complete conversion of feldspathoid (nepheline, sodalite?
The effects of postmagmatic alteration in samples chosen for bulk rock analyses were assessed using petrographic and textural features where possible.
16 are particularly noteworthy as Ce/Yb and Zr/Nb ratios are parameters least affected by postmagmatic alteration (Gill 1981).
The carbonate rocks were transformed into marble and, at a postmagmatic stage, mineralization formed in the contact zone with the intrusive rocks.
It is interesting to note that all of these minerals are typical of a retrograded calcic skarn (aposkarn) in a postmagmatic phase.