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Protolith origin and plate tectonic setting of metamorphic complexes in the Timor fold and thrust belt, Indonesia
  • Michael Maurice Earle
Michael Maurice Earle

Corresponding Author:earlemm@gmail.com

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Geologically, Eastern Indonesia is a 180o orocline created by the dynamic interaction of three opposing tectonic plates. Additional complexity resulted from the sporadic breakup of Gondwana that fragmented the northern margin of New Guinea-Australia (NGA) and caused crustal blocks to collide with SE Asia before the Pliocene arc-continent collision with Australia. One consequence is that protoliths of two distinct metamorphic associations on Timor have mixed Gondwanan and SE Asian affinities. This article presents a reclassification of the metamorphic rocks of Timor that links their formation and radiometric ages to tectonic provenance and key events that occurred as NeoTethys was consumed by subduction. Four periods of metamorphism are recognised, plus radiometric dating evidence of peak and cooling P-T conditions and the tectonic settings that caused metamorphism and deformation of different complexes on the island. Key conclusions are: [1] a basement complex accreted to the Sunda margin from Gondwana in the Cretaceous. [2] Oceanic crust and pelagic sediment of Jurassic to Early Cretaceous age form a tectono-metamorphic complex comprised of volcanic greenstones, greenschists, mn-rich sediments, and radiolarian cherts metamorphosed in the pre-collision Sunda forearc. [3] Eocene back arc spreading led to injection of gabbro and peridotite, and a metamorphic episode that peaked at 45Ma. [4] The metamorphosed Permo-Triassic Aileu Complex originated on Gondwana but includes Sunda upper plate peridotite that became attached during subduction and extrusion at the close of the Miocene.
05 May 2023Submitted to ESS Open Archive
05 May 2023Published in ESS Open Archive