Origin of mélange complexes in the Sunda and Banda arcs: Tectonic, sedimentary, or diapiric mélange

Abstract

The origin of mélange complexes has been the subject of speculation of geologists since their first recognition in the 1900s. Type of mélange complex plays a role in the tectonic reconstruction of active margin. Several locations in the southern Sundaland margin expose remnant of Mesozoic subduction zone as basement and sedimentary rocks in mélange complexes. Ciletuh, Luk Ulo, and Meratus formed along the southern margin of Cretaceous Sundaland subduction system have been known as tectonic mélanges based on observation of the exposed rocks and its structural configuration. However, mélange complexes in the western Sunda arc (Nias) and Banda arc (Timor) have been concluded to form as diapiric mélange rather than tectonic origin. Recent studies in these two areas showed that mud diapirism was developed in a dynamically active environment. The role of tectonism in these mélange complexes appears to be indirect. Here, we described results of published results on mélanges along the Sunda and Banda arc to understand the mechanism of their processes.