Tethyan suturing in Southeast Asia; zircon U-Pb and Hf-O isotopic constraints from Myanmar ophiolites

Ophiolites that crop out in Southeast Asia represent the relics of the Tethys Ocean, which existed between the continents of Gondwana and Laurasia during much of the Mesozoic. Two ophiolite belts in Myanmar, i.e., the Eastern Belt and the Western Belt, have been conventionally regarded as parts of a...

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Bibliographic Details
Published in:Geology (Boulder) 2016-04, Vol.44 (4), p.311-314
Main Authors: Liu Chuanzhou, Liu Chuanzhou, Chung, Sun-Lin, Wu Fuyuan, Wu Fuyuan, Zhang Chang, Zhang Chang, Xu Yang, Xu Yang, Wang Jiangang, Wang Jiangang, Chen Yi, Chen Yi, Guo Shun, Guo Shun
Format: Article
Language:English
Subjects:
absolute age
amphibolites
Asia
Burma
diorites
Far East
gabbros
geochemistry
Geochronology
Geology
Geophysics
Gondwana
hafnium
Hf-177/Hf-176
igneous and metamorphic rocks
igneous rocks
isotope ratios
Isotopes
Laurasia
Mass spectrometry
Mesozoic
metals
metamorphic rocks
metasomatic rocks
nesosilicates
O-18/O-16
ophiolite
ophiolite complexes
orthosilicates
oxygen
Petrology
plate tectonics
plutonic rocks
rodingite
silicates
solid Earth (tectonophysics)
Southeast Asia
stable isotopes
suture zones
Tethys
U/Pb
zircon
zircon group
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Summary:Ophiolites that crop out in Southeast Asia represent the relics of the Tethys Ocean, which existed between the continents of Gondwana and Laurasia during much of the Mesozoic. Two ophiolite belts in Myanmar, i.e., the Eastern Belt and the Western Belt, have been conventionally regarded as parts of a single suture connecting with the Yarlung-Tsangpo suture in the Tibetan Plateau and displaced by the dextral Sagaing Fault. Here we present for the first time a combined analysis of zircon secondary ion mass spectrometry U-Pb ages and Hf-O isotopes of two Myanmar ophiolites, the Kalaymyo Ophiolite from the Western Belt and the Myitkyina Ophiolite from the Eastern Belt. Our results show that the Kalaymyo Ophiolite has an Early Cretaceous age (ca. 127 Ma), coeval with Neo-Tethyan ophiolites along the Yarlung-Tsangpo suture. In contrast, the Myitkyina Ophiolite was formed during the Middle Jurassic (ca. 173 Ma) and thus the Eastern Belt is the southern continuation of the Meso-Tethyan Bangong-Nujiang suture in the Tibetan Plateau. Consequently, we argue that the two Myanmar Ophiolite belts belong to two different sutures of the Meso-Tethys and Neo-Tethys, and that the boundary between the Sibumasu and west Burma Blocks is a Jurassic suture rather than a transcurrent shear zone.
ISSN:0091-7613
1943-2682
DOI:10.1130/G37342.1