Temperature-HF Fugacity Trends During Crystallization of Calcite Carbonatite Magma in the Fen Complex, Norway

摘要: Calcite carbonatite (scvite), associated apatite cumulates and contact metasomatic phlogopite-rocks in the Fen complex (S. Norway) contain coexisting phlogopite. Two distinct compositional groups are recognized: fluorapatite (XF = 0.5--0.8) coexists with hydroxy-phlogopite XF 0.110.26, whereas hydroxyapatite 0.34-0.44) low-F --~ 0.03). Apatite-biotite geothermometry suggests that minerals equilibrated at igneous temperatures (less than 1200 to ca. 625 ~ were not significantly disturbed by late low-temperature re-equilibration. This, combined HF-barometry based on apatite-fluid phlogopite-fluid F-OH exchange equilibria, makes it possible recognize two crystallization trends different levels of hydrogen fluoride fugacity. The existence such reflects internal buffering HI: fugacity and/or recorded differences HF suggest or more independent semi-independent lines magmatic descent gave rise calcite magma complex. Combined apatite-phlogopite barometry is a useful tool enabling us see through post-magmatic alteration carbonatites, establish primary controls even cases where carbonate iron-titanium oxide have re-equilibrated much lower temperatures.