The halogen budget of the shoshonitic series of the Bolivian Altiplano has been assessed, and found that they have contents similar to other enriched basalts worldwide. We observe F (range between 0.02 and 0.24 wt%) behaviour as similar to that of crustal derived elements in this environment, while Cl (range between 0.01 and 0.26 wt%) is more complex and probably is controlled by heterogenous source regions. F and Cl both decrease in abundance towards the more evolved end of the series that, despite large distances (~300 km) between the furthest samples, bear a striking similarity in numerous geochemical indices. It follows that the lack of F in Bolivian Sn-systems is due to petrogenetic process rather than parental material. A model involving amphibole fractionation promoted by the anomalously thick crust is proposed to account for these observations.
|Number of pages||10|
|Journal||Revista brasileira de geociências : órgão da Sociedade Brasileira de Geologia|
|Publication status||Published - 2012|