Garnier V., Ohnenstetter D., Giuliani G., Maluski H., Deloule E., Trong T. P., Van L. P., Quang V. H. (2005). Age and significance of ruby-bearing marble from the Red River Shear Zone, northern Vietnam. Canadian Mineralogist, 43 (Part 4), p. 1315-1329. ISSN 0008-4476.
Titre du document
Age and significance of ruby-bearing marble from the Red River Shear Zone, northern Vietnam
Garnier V., Ohnenstetter D., Giuliani G., Maluski H., Deloule E., Trong T. P., Van L. P., Quang V. H.
Source
Canadian Mineralogist, 2005,
43 (Part 4), p. 1315-1329 ISSN 0008-4476
Marble-hosted ruby deposits occur in the Lo Gam tectonic zone along the northeastern flank of the Day Nui Con Voi Range in the Red River Shear Zone, in the northern part of Vietnam. Crystals of zircon included in ruby and spinel from Luc Yen and An Phu deposits were dated in situ by the U-Pb method with an ion microprobe. The patchy zoning of the zircon crystals and the wide range of ages (266-38 Ma) provide evidence for a complex metamorphic history, with at least two main thermal events: (1) Zircon included in spinel crystals probably crystallized during the Permian (256.6 +/- 9.4 Ma), with a possible reopening of their U-Pb system in the early Triassic (231.7 +/- 5.6 Ma). (2) Ruby formed at about 38 Ma when the Red River Shear Zone was the site of ductile deformation during the peak of metamorphism. The dating of zircon and phlogopite syngenetic with ruby documents the temporal relationship between high-temperature metamorphism and the cooling history of the Red River metamorphic belt. Ruby deposits hosted by marble sequences, in central and southeastern Asia seem to be an excellent marker; they allow an interpretation of the timing of the activity of Cenozoic structures linked to the collision between Indian and Eurasian continents.
