Problems with pseudosection (tcds55_p07 dataset)

[Samanta Serra Varela]

Hello!
I´m having two problems with my pseudosection: I´m currently using the tcds55_p07 dataset and it is the first time a phase termed "O" appear in my pseudosection. I don´t know why it appears in the phase diagram. I´m modelling without Fe3 and Ti SI(53.103)AL(28.906)CA(0.348)MG(3.166)FE(6.894)K(5.138)NA(1.514)MN(0.076)H(37.269)O(?)
Moreover, margarite appears as a pure phase in the diagram and I was wondering if I should use the ds6 dataset that includes a model for margarite even though this phase is not near the field that contains the association of my rock. I would appreciate your opinion on the matter.
Thanks in advance for the help.
Kind regards
Samanta