Figure 4:

(a) Arrhenius plot of oxygen diffusion coefficients in spinel, åkermanite, gehlenite, diopside, forsterite, and anorthite under dry and wet conditions. Data from GILETTI et al (1978), OISHI & ANDO (1984), FARVER (1989), YURIMOTO et al (1989), and RYERSON & MCKEEGAN (1994). (b) Temperature and time dependencefor a complete oxygen isotopic exchange in a 10 μm-sized anorthite (typical size of plagioclase grains in Kaba chondrules) under dry (red line) and wet (blue line) conditions. Under the estimated conditions of metasomatic alteration ofKaba (200–300°C), it takes between 0.1 and 0.001 Ma to exchange oxygen isotopic cormposition of plagioclase ivith an aqueous fuid.