Abstract:

The possible genetic relationship between iron oxide-copper-gold (IOCG) and magnetite-(apatite) Mt(Ap) (also known as Kiruna type) deposits has been a controversial topic for many years. Spatial and age relationships, and relatively similar mineralogy, between these two types of deposits, has led many researchers to suggest that MtAp and IOCG deposits are opposite endmembers in a continuous spectrum of mineralization. The Montecristo mining district in northern Chile is one of a few places on Earth where MtAp mineralization occurs with IOCG mineralization in the same mining district. The Abundancia deposit at Montecristo contains both mineralization types, often with cross-cutting relationships (though both types of mineralization occur there, it is primarily known as an IOCG deposit). The San Juan MtAp deposit at Montecristo is a massive MtAp dyke (~4m wide by ~600m long) and thought to be temporally and spatially related to Abundancia. In the current MSc project several types of analyses were done in order to determine if a genetic relationship exists between the two deposits. This includes ⁴⁰Ar-³⁹Ar dating of actinolite, whole-rock Pb, Sr, and Nd isotopes, and EPMA analyses of major and minor elements in actinolite, magnetite, and apatite, X-ray maps of actinolite, and LA-ICPMS analyses of trace elements in actinolite, from both the Abundancia and San Juan deposits. Furthermore, S isotopes, Re-Os dating of molybdenite, and LASS U-Pb dating and Hf tracer isotopes in zircon from the host rock for the Abundancia deposit were also done. The results from this study will help provide a better understanding if IOCG and MtAp deposits are genetically related or not by identifying chronological and geochemical similarities in the IOCG and MtAp mineralization types. The results from this study will contribute to a better understanding of the formation of these type of deposits in northern Chile and will be useful for mineral exploration purposes elsewhere.

Biography of the presenter: Laura Mateo received her BSc in geology (2009) degree from the University of the Basque Country in northern Spain. Following completion of her BSc degree, she worked as a project geologist for seven years for the Mineral Resources Unit at the Geological Survey of Chile, in Santiago, working in the areas of metallogenesis of ore deposits. Currently, she is working on finishing her MSc degree in geology at the Memorial University of Newfoundland.

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Laura Mateo