TY - JOUR
T1 - The Burmese Jade Mines belt
T2 - origins of jadeitites, serpentinites and ophiolitic peridotites and gabbros
AU - Searle, M.P.
AU - Palin, R.M.
AU - Gardiner, N.J.
AU - Htun, Kyi
AU - Wade, J.
N1 - Funding: MPS and NJG thank the Oxford–Burma Aung San Suu Kyi Trust and the Fell Fund for funding the fieldwork in Myanmar.
PY - 2023/7/21
Y1 - 2023/7/21
N2 - 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.
AB - 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.
UR - https://doi.org/10.6084/m9.figshare.c.6655269
U2 - 10.1144/jgs2023-004
DO - 10.1144/jgs2023-004
M3 - Article
SN - 0016-7649
VL - 180
JO - Journal of the Geological Society
JF - Journal of the Geological Society
IS - 4
M1 - jgs2023-004
ER -