Abstract

Metamorphosed massive sulfide deposits in the Swedish Caledonides were investigated using sphalerite geobarometry and arsenopyrite geothermometry. The sphalerite investigations yield pressure estimates of 3 to 5 kb for six deposits from host rocks of greenschist-lower amphibolite facies. A bimodal FeS distribution is apparent for the chlorite-grade deposits whereas the FeS distribution in biotite-grade deposits is unimodal. The arsenopyrite geothermometry is apparently sensitive to high contents (>0.2 wt %) of either of the trace elements Co and Ni, and possibly also of Sb. Temperature estimates for six deposits from the chlorite zone of greenschist facies yield 371 degrees + or - 45 degrees C, whereas one deposit from the biotite zone gives a temperature of 422 degrees + or - 25 degrees C. The pressure and temperature data obtained for the deposits correspond excellently with the metamorphic grade of the host rocks. Thus, sphalerite geobarometry and arsenopyrite geothermometry can be applied successfully to metamorphosed sulfide orebodies if attention is paid to textural relationships and minor element distribution in the minerals investigated.

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