Marble-hosted ruby deposits from Central and Southeast Asia : towards a new genetic model

2008

Article référencé dans le Web of Science WOS:000259917500011

Garnier V., Giuliani Gaston, Ohnenstetter D., Fallick A. E., Dubessy J., Banks D., Vinh H. Q., Lhomme T., Maluski H., Pecher A., Bakhsh K. A., Van Long P., Trinh P. T., Schwarz D.

Ore Geology Reviews, 2008, 34 (1-2 Special Issue), p. 169-191 ISSN 0169-1368

Marble-hosted ruby deposits represent the most important source of colored gemstones from Central and South East Asia. These deposits are located in the Himalayan mountain belt which developed during Tertiary collision of the Indian plate northward into the Eurasian plate. They are spatially related to granitoid intrusions and are contained in platform carbonates series that underwent high-grade meta morph ism. All occurrences are located close to major tectonic features formed during Himalayan orogenesis, directly in suture zones in the Himalayas, or in shear zones that guided extrusion of the Indochina block after the collision in South East Asia. Ar-Ar dating of micas syngenetic with ruby and U-Pb dating of zircon included in ruby gives evidence that these deposits formed during Himalayan orogenesis, and the ages document the extensional tectonics that were active, from Afghanistan to Vietnam, between the Oligocene and the Pliocene. The petrography shows that ruby-bearing marbles formed in the amphibolite facies (T=610 to 790 degrees C and P-6 kbar). A fluid inclusion Study defines the conditions of gem ruby formation during the retrograde metamorphic path (620