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Jurassic to Miocene magmatism and metamorphism in the Mogok metamorphic belt and the India-Eurasia collision in Myanmar


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Barley, ME, Pickard, AL, Zaw, K, Rak, P and Doyle, MG 2003 , 'Jurassic to Miocene magmatism and metamorphism in the Mogok metamorphic belt and the India-Eurasia collision in Myanmar' , Tectonics, vol. 22, no. 3 , pp. 4-1 , doi: 10.1029/2002TC001398.

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Situated south of the eastern Himalayan syntaxis at
the western margin of the Shan-Thai terrane the highgrade
Mogok metamorphic belt (MMB) in Myanmar occupies a key position in the tectonic evolution of Southeast Asia. The first sensitive high-resolution ion microprobe U-Pb in zircon geochronology for the MMB shows that strongly deformed granitic orthogneisses near Mandalay contain Jurassic (~170 Ma) zircons that have partly recrystallized during ~43 Ma high-grade metamorphism. A hornblende syenite
from Mandalay Hill also contains Jurassic zircons with
evidence of Eocene metamorphic recrystallization
rimmed by thin zones of 30.9 plus or minus 0.7 Ma magmatic
zircon. The relative abundance of Jurassic zircons in
these rocks is consistent with suggestions that southern
Eurasia had an Andean-type margin at that time. Mid-
Cretaceous to earliest Eocene (120 to 50 Ma) I-type
granitoids in the MMB, Myeik Archipelago, and Western Myanmar confirm that prior to the collision of India, an up to 200 km wide magmatic belt extended along the Eurasian margin from Pakistan to Sumatra.
Metamorphic overgrowths to zircons in the orthogneiss
near Mandalay date a period of Eocene (~43 Ma)
high-grade metamorphism possibly during crustal
thickening related to the initial collision between
India and Eurasia (at 65 to 55 Ma). This was
followed by emplacement of syntectonic hornblende
syenites and leucogranites between 35 and 23 Ma.
Similar syntectonic syenites and leucogranites intruded
the Ailao Shan-Red River shear belt in southern China
and Vietnam during the Eocene-Oligocene to Miocene,
and the Wang Chao and Three Pagodas faults in
northern Thailand (that most likely link with the MMB)
were also active at this time. The complex history of
Eocene to early Miocene metamorphism, deformation,
and magmatism in the MMB provides evidence that it
may have played a key role in the network of
deformation zones that accommodated strain during
the northwards movement of India and resulting
extrusion or rotation of Indochina.

Item Type: Article
Authors/Creators:Barley, ME and Pickard, AL and Zaw, K and Rak, P and Doyle, MG
Keywords: SE Asia, Myanmar, granitoids, metamorphism, zircon dating, geochronology, SHRIMP, Granite, Mogok
Journal or Publication Title: Tectonics
ISSN: 0278-7407
DOI / ID Number: 10.1029/2002TC001398
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