Petrography characteristics of Quaternary volcanoes in Rawa Danau Caldera, Banten Province

The caldera from volcano eruptions often been found in Indonesia. However, the caldera which has swamp and lake such as Rawa Danau, Serang, Banten is rare in Indonesia. It encompasses with a swamp at the outer part and lake on the central part. The caldera surrounded by five Quaternary volcanoes, which are Mount Karang, Mount Parakasak, Mount Aseupan at the south, and Mount Tukung-Gede along with Mount Marikangen at the north side of the swamp. The Rawa Danau location is about 50 km to the East of Krakatau Volcano, so it might have been some linkage to its rock properties. This similarity can be seen from the textures and mineral compositions of their thin sections. Most of the volcano material resulted from different volcanoes. The challenging work was how to differentiate their sources eruption in the field because the weathering rate is high. Thus, this paper aims to differentiate the products of each young volcanoes in Rawa Danau using petrography analysis. In general, young volcanoes in Rawa Danau have trachytic and porphyritic textures, with plagioclase, pyroxene, and opaque as the phenocryst and microlite plagioclase as the matrix. The plagioclase can be found around 15-30 % as the phenocryst, microlite plagioclase as the matrix. The plagioclase type is around An55 compared with Krakatau which has An58. The magma characteristics of these young volcanoes might have a similarity with the magma of Krakatau Volcano.