Experimental studies on trace element partitioning between mafic minerals and alkaline melts

Abstract

Trace elements are a small fraction of geochemical systems and their variations are sensitive to geological processes because they are influenced by the physic-chemical properties of the system. Therefore, these elements help to understand and to model the genesis and evolution of various magmatism. The present research proposal aims to determine trace elements partition coefficients (D_i^(Crytal/melt)) for mafic minerals by means of fusion / crystallization experiments from natural and synthetic compositions, similar to those observed in mafic-ultramafic rocks of the Serra do Mar Alkaline Province, under conditions of pressure, temperature and volatile activity compatible with those verified in this province. Although there are already coefficients in the literature, they do not cover the compositions and crystallization conditions of most of the rocks of the magmatism in question. In order to fill this gap, experimental simulation techniques with piston-cylinder and vertical tubular furnace and high spatial resolution (MEV, EMPA, LA-ICP-MS) of the products will be used. Thus, it is expected to obtain geochemical parameters that allow a more precise modeling of the genesis and evolution of crystallized alkaline magmas in subvolcanic and plutonic environments and contribute to a better understanding of the magmatic processes that have built the province, as well as similar provinces on the South American platform.