Dear Bettina,

There is a study which includes oxygen isotope analysis in a metamorphic
terrain (Grenvillian of SW Sweden), although not giving an
apatite-mineral/calcite fractionation as you asked for. The reference
is:

N.C. Munksgaard and H.P. Zeck, Oxygen-isotope systematics of a strongly
recrystallized granitic rock complex, Grenvillian Belt, SW Sweden.,
Contrib. Mineral. Petrol. 85, 67-73, 1984.

Anorther place to look for oxygen isotope compositions of apatites is in
studies on biogenic apatites (phosphates), although there fractionations
at low temperatures will be found only. Anyway, some refs:

A. Shemesh, Y. Kolodny and B. Luz, Oxygen isotope variations in
phosphate of biogenic apatites, II Phosphorite rocks. Earth Planet. Sci.
Lett. 64, 405-416, 1983.

L.K. Aycliffe, H.H. Veeh and A.R. Chivas, Oxygen isotopes of phosphate
and the origin of island apatite deposits. Earth Planet. Sci. Lett. 108,
119-129, 1992.

I hope some of this is useful for you.
Best wishes, Pier.
**************************************************************
Dr. P.A. de Groot
University of the Witwatersrand
Economic Geology Research Unit
Department of Geology
Private Bag 3
2050 Johannesburg
South Africa
Tel.    +27 11 7162564
Fax.    +27 11 3391697
E-mail  <[log in to unmask]>

Visit the combined HOME-PAGE of EGRU-Geology on the Internet:
        http://www.wits.ac.za/science/geology/1stpage.htm
**************************************************************