Editing Sunda Arc (section)

=== Back-arc volcanism ===
The magmatic activities along the back-arc may or may not relate to the main arc materials. Magma and lava appear to have originated from molten materials at a deeper part of the mantle as supported by a higher K<sub>2</sub>O/Na<sub>2</sub>O ratio in comparison to other parts of Sunda Arc.<ref name=":62"/><ref name=":42"/> The most salient volcanoes in the back-arc region are Lasem, [[Mount Muria|Muria]], and [[Bawean]] in which their volcanic rocks show complex patterns in terms of chemical signature.<ref name=":62" />[[File:Screen Shot 2563-11-08 at 11.20.12.png|thumb|upright=2.5|A geologic map of Indonesia Region (ESRI, USGS, HERE, Garmin, NOAA)]]