Fallick A. E., Giuliani Gaston, Rigaudier T., Boyce A. J., Pham V. L., Pardieu V. (2019). Remarkably uniform oxygen isotope systematics for co-existing pairs of gem-spinel and calcite in marble, with special reference to Vietnamese deposits. Comptes Rendus Geoscience, 351 (1), p. 27-36. ISSN 1631-0713.
Titre du document
Remarkably uniform oxygen isotope systematics for co-existing pairs of gem-spinel and calcite in marble, with special reference to Vietnamese deposits
Fallick A. E., Giuliani Gaston, Rigaudier T., Boyce A. J., Pham V. L., Pardieu V.
Source
Comptes Rendus Geoscience, 2019,
351 (1), p. 27-36 ISSN 1631-0713
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.
Plan de classement
Géologie et formations superficielles [064]
Description Géographique
VIET NAM ; TANZANIE ; NEPAL ; MYANMAR ; TADJIKISTAN ; PAKISTAN ; KENYA
