Horizon 1 1 17 ACL : Articles dans des revues avec comité de lecture répertoriées par l'AERES Comptes Rendus Geoscience 27-36 Marble deposits Asia East Africa Spinel-calcite pair Oxygen isotope fractionation Temperature of formation VIET NAM TANZANIE NEPAL MYANMAR TADJIKISTAN PAKISTAN KENYA 2019 fdi:010075174 ENG Comptes Rendus Geoscience 1631-0713 ISI:000458134400004 1 10.1016/j.crte.2018.11.008 https://www.documentation.ird.fr/hor/fdi:010075174 https://www.documentation.ird.fr/intranet/publi/2019/02/010075174.pdf 351 Horizon (IRD) Oxygen isotope systematics for co-existing pairs of gem-spinel and calcite in marble from Vietnam and other worldwide deposits have been determined in order to characterize the O-isotope fractionation between calcite and spinel. In Vietnam, the Delta O-18(cc-sp) (= 3.7 + 0.1 parts per thousand for six samples from the An Phu and Cong Troi deposits) is remarkably constant. The combination of these data with those obtained on calcite-spinel pairs of Paigutan (Nepal, n = 2), Ipanko (Tanzania, n = 1), and Mogok (Myanmar, = 2) are also consistent with an overall Delta O-18(cc-sp) of 3.6 + 0.3 parts per thousand for all the spinel samples (n = 11). The straight line correlation delta O-18(cc) = 0.96 delta O-18(sp) + 4.4 is excellent despite their worldwide geographic spread. The increment method of calculating oxygen isotope fractionation gave a geologically unreasonable temperature of formation for both minerals at 1374 degrees C when compared to temperatures obtained by mineral assemblage equilibrium of these marble type deposits, between 610 and 750 degrees C. The constant Delta O-18(cc-sp) reflects a constant temperature for this amphibolite facies assemblage, whose current best estimate is calculated at 620 + 40 degrees C, but unquantified uncertainties remain. 064 UR234 Vietnam