The Burmese Jade Mines belt : origins of jadeitites, serpentinites and ophiolitic peridotites and gabbros
Date
21/07/2023Metadata
Show full item recordAbstract
Ophiolitic peridotites in Burma (Myanmar) occur along three major tectonic zones, the Kaleymyo–Nagaland suture, Indo-Burman ranges, the Jade Mines belt, and the Tagaung–Mytkyina belt. These belts all show harzburgite–lherzolite–dunite peridotites, but the Hpakan-Taw Maw region (Jade Mines belt) hosts jadeitites including pure jadeite, mawsitsit (chromium-rich jadeite) kosmochlore (chromium-rich clinopyroxene), and albitite. High Na and Al contents of jadeitites require either very unusual Al-rich, Si-poor protoliths, or extensive fluid metasomatism, or both. The Hpakan jadeitites formed by Na-, Al-, (and Si) metasomatic alteration of pyroxenite–wehrlite intrusions into harzburgite–dunite, from widespread fluid alteration. Fluids could have been derived from a mid-Jurassic intermediate pressure subduction event during ophiolite formation and emplacement. In the Indawgyi Lake area, normal ophiolitic peridotites, including harzburgite and dunite with pyroxenite veins, have not been jadeitised. Gabbros related to the Jade Mines ophiolite gave a U-Pb zircon age of 169.71±1.3 Ma (MSWD 2.2), similar timing to the Myitkyina ophiolite (173 Ma) to the east, suggesting that the ophiolite belts were originally continuous. The jade ‘boulders’ in the Uru conglomerate beds at Hpakan have also resulted from normal in situ serpentinisation weathering processes, followed by limited fluvial mass transport processes along the Uru river.
Citation
Searle , M P , Palin , R M , Gardiner , N J , Htun , K & Wade , J 2023 , ' The Burmese Jade Mines belt : origins of jadeitites, serpentinites and ophiolitic peridotites and gabbros ' , Journal of the Geological Society , vol. 180 , no. 4 , jgs2023-004 . https://doi.org/10.1144/jgs2023-004
Publication
Journal of the Geological Society
Status
Peer reviewed
ISSN
0016-7649Type
Journal article
Description
Funding: MPS and NJG thank the Oxford–Burma Aung San Suu Kyi Trust and the Fell Fund for funding the fieldwork in Myanmar.Collections
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