Leti (island)

The geology of Leti reveals how continental crust is subducted to at least 30 km depth causing pieces to rip off, then move up the subduction channel back to the surface [1] For example, Leti is the only island in the Maluku chain with in situ blueschist.

This rare occurrence of blueschist in Leti was first documented in 1915 by Dutch geologists who spent one month on the island producing a detailed geological map, cross section and description of the geological units[2] In their 220 page monograph they report finding sodic amphibole (crossite) in mafic and pelitic metamorphic rocks structurally overlain by an ultramafic body.

They also found melange below and around the ultramafic body with blocks of Tertiary limestone scattered among a variety of other igneous, metamorphic and sedimentary material.

They relate this unit to melange of similar composition reported in West Timor.

Arc-continent collision, Frontiers in Earth Sciences 2, Springer Verlag, Heidelberg, p. 163-211. overschuivingsbladen op de eilanden Timor en Letti.