Fig. 4 | Nature Communications

Fig. 4

From: Global Fe–O isotope correlation reveals magmatic origin of Kiruna-type apatite-iron-oxide ores

Fig. 4

Oxygen isotope results. a Oxygen isotopes of magnetite samples from Kiruna, Grängesberg, El Laco, and the Bafq district from this study are compared to reference samples from layered igneous intrusions, recent volcanic magnetites, and low-temperature or hydrothermal ore deposits as well as b data from the Chilean Iron Belt14, the Pea Ridge and Pilot Knob deposits48. The range of typical igneous magnetite is outlined in the reference box50. The majority of magnetite samples from apatite-iron oxide ores plot within the reference field for common magmatic δ18O-values and overlap with magnetite values from recent volcanic rocks and layered intrusions. The low-temperature or hydrothermal reference suite, together with low-temperature magnetite literature data14,44, plot dominantly to the left of the magmatic magnetite field, with only one exception, a magnetite from the Fe-skarn deposit at Dannemora. This particular outlier comes from a part of the deposit (Konstäng) which itself represents a geochemical anomaly within the Dannemora deposit. Our values for El Laco overlap with results from previous studies5,14,17,18,32

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