1 samples, with dominating sanidine crystals, anorthoclase glomerocrysts and poikilocrysts (Figure 10).
In thin section (Figure 14) they are classified as vitric and vitric-crystalline flow tuffs (Figure 5) with occasional plagioclase, anorthoclase and sanidine free phenocrysts in a vitroclastic matrix.
with anorthoclase phenocrysts up to 1,5 cm (Figure 15).
all samples have high contents of alkalis (7-10%), in which Na content is greater than K content, which is consistent with anorthoclase, Na-amphibole and Na-Pyroxene crystallization.
On the other hand, anorthoclase poikilocrysts with plagioclase nucleus (Figures 3A and 6F) suggest the following hypothesis (Pardo-Villaveces, 2004): (1) following Carmichael et al.