Influence of Weathering on the Engineering Properties of Dacites in Northeastern Turkey
Figure 6
Photomicrographs showing plagioclase phenocrystals in the dacites representing each weathering grade from I to IV ((a)–(d)) (crosed nicols, ; Plj phe.: plagioclase phenocrystal). Fresh dacite with an unweathered plagioclase phenocrystal showing cooling microfractures and opaque inclusions, and with unstained plagioclase microlites in abundance (a), slightly weathered dacite with a slightly sericitized plagioclase phenocrystal and lesser amount of plagioclase microlites (b), moderately weathered dacite with a plagioclase phenocrystal showing an increasing amount of sericite around the edges and center (c), and highly weathered dacite with a plagioclase phenocrystal extensively weathered to clay minerals (d).
