Many of the islands of Indonesia (Java, Sumatra, Borneo), which are located adjacent to a subduction zone next to the edge of the continental shelf of SE Asia, consist of felsic lava. This means that the lava that produces these islands is derived from

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The presence of felsic lava in the islands of Indonesia suggests that the lava originates from the melting of continental shelf material along with ocean floor material. This is because felsic lava contains a high percentage of silica, which is typically found in continental crust rather than oceanic crust. Additionally, the proximity of the islands to a subduction zone suggests that the continental shelf material is being subducted and melted in the mantle, resulting in the formation of the felsic lava that produces these islands.

Many of the Islands of Indonesia (Java, Sumatra, Borneo), Which