Reference : The stability of primary alluaudites in granitic pegmatites: an experimental investig...
Scientific journals : Article
Physical, chemical, mathematical & earth Sciences : Earth sciences & physical geography
http://hdl.handle.net/2268/7849
The stability of primary alluaudites in granitic pegmatites: an experimental investigation of the Na-2(Mn2-2x Fe1+2x )(PO4)(3) system
English
Hatert, Frédéric mailto [Université de Liège - ULg > Département de géologie > Minéralogie et cristallochimie >]
Fransolet, André-Mathieu mailto [Université de Liège - ULg > Département de géologie > Minéralogie et cristallochimie >]
Maresch, Walter W. [> > > >]
Oct-2006
Contributions to Mineralogy & Petrology
Springer
152
4
399-419
Yes (verified by ORBi)
International
0010-7999
New York
[en] primary alluaudites ; Na-Mn-Fe-2-Fe3+ phosphates ; phase relations ; petrological implications ; pegmatites
[en] In order to assess the geothermometric potential of the Na-2(Mn2-2x Fe1+2x )(PO4)(3) system (x = 0-1), which represents the compositions of natural weakly oxidized alluaudites, we performed hydrothermal experiments between 400 and 800 degrees C, at 1 kbar, under an oxygen fugacity (f(O-2)) controlled by the Ni-NiO (NNO), Fe2O3-Fe3O4 (HM), Cu2O-CuO (CT), and Fe-Fe3O4 (MI) buffers. When f(O-2) is controlled by NNO, single-phase alluaudites crystallize at 400 and 500 degrees C, whereas the association alluaudite + maricite appears between 500 and 700 degrees C. The limit between these two fields corresponds to the maximum temperature that can be reached by alluaudites in granitic pegmatites, because maricite has never been observed in these geological environments. Because alluaudites are very sensitive to variations of oxygen fugacity, the field of hagendorfite, Na2MnFe2+Fe3+(PO4)(3), has been positioned in the f(O-2)-T diagram, and provides a tool that can be used to estimate the oxygen fugacity conditions that prevailed in granitic pegmatites during the crystallization of this phosphate.
Researchers ; Professionals ; Students
http://hdl.handle.net/2268/7849

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