Clay Mineralogy of the Middle Miocene Paghumayan Formation Vallehermoso Negros Oriental Philippines

抄録

Clay minerals of stratified tuff and mud rocks of the Middle Miocene Paghumayan Formation in Vallehermoso Negros Oriental Philippines were examined. The results showed homogeneity of clays in the sedimentary sequence with smectite as the only phyllosilicate present. Feldspar and zeolites are typical which therefore yield the mineral assemblage smectite-feldspar-zeolite. A calcareous horizon may be present as revealed by one sample detected to contain almost entirely of crystalline calcite with very minimal smectite.