Geochemistry of the Davis and Aurora Banks: Possible implications on evolution of the North Scotia Ridge

Abstract

Geochemistry of volcanic rocks of the Davis and Aurora Banks, North Scotia Ridge, is presented with the aim to infer their petrogenesis and implications in regional tectonics. The analyses show consistent major and trace element patterns which are conformable with calc-alkaline series volcanics with typical signatures of subduction zone magma. The source melt of the studied volcanics is deciphered to be subduction zone mantle wedge metasomatised by sediments. Geochemical analyses of the volcanics from the Davis and Aurora Banks are compared with geochemical data of volcanics of the South Sandwich island arc and Jurassic, Cretaceous and Paleogene arc volcanics of Patagonia, South America. This comparative study shows that the Davis and Aurora Banks' volcanics are akin to Cretaceous arc volcanics of the Hardy Formation, South America. Rocks of Hardy Formation are also reported from South Georgia. Further, based on established trace element ratio diagrams, it is deciphered that source magma characteristics of arc volcanics from South Georgia, Hardy Formation and Davis and Aurora Banks are the same. Integration of our findings with previous studies, we propose a geodynamic model for the Davis and Aurora Banks in conformity with accepted model for the evolution of the West Scotia Sea.