Suture Dynamics of the Banda Arc Collision Zone: Geochemical and Age Analysis of Ultramafic and Mafic Bodies in Timor, Indonesia
Abstract
New age and geochemical data confirm that most ultramafic bodies on the north coast of Timor are derived from the distal reaches of the Australian continental margin lower plate that was exhumed by extension during Late Paleozoic to Mesozoic rifting. The ultramafic bodies were accreted to Timor during Late Miocene to present arc-continent collision. One of the lherzolitic ultramafic bodies near Caicua was previously unknown, but yields clear isotopic indicators that it is kin to the Hili Manu mafic and ultramafic complex further to the west. Zircon grains from metagabbro of the Hili Manu complex have cores with mostly Early Permian ages and rims of Latest Miocene ages. Isotopic analysis indicates abyssal plain, or passive margin affinity of the Caicua ultramafic body. One important exception to this pattern are mafic and ultramafic bodies associated with the Ocussi volcanics, which yield Miocene and Pliocene ages and supra-subduction zone chemical signatures. The Ocussi body is clearly part of the upper plate of the collision and formed after collision initiated further to the east. It is also structurally higher than the Hili Manu complex and has no affinities with the Australian plate. This study documents that both the upper and lower plates of the active arc-continent collision contribute mafic and ultramafic rocks to the evolving suture zone between the Indo-Australian and Asian plates in the Banda Arc region.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2013
- Bibcode:
- 2013AGUFM.T51B2471V
- Keywords:
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- 8140 TECTONOPHYSICS Ophiolites;
- 8170 TECTONOPHYSICS Subduction zone processes;
- 9320 GEOGRAPHIC LOCATION Asia;
- 8139 TECTONOPHYSICS Obduction tectonics