Magmatism and tectonic evolution of West Antarctica

West Antarctica is mainly composed of five distinct micro-continental blocks, namely Haag Nunataks, Antarctic Peninsula, Thurston Island, Marie Byrd Land and Ellsworth-Whitmore Mountains. In order to understand the geological evolution of West Antarctica, this paper presents a brief overview of the main magmatic events of the five blocks and their tectonic significance. The oldest rock is the Precambrian orthogneiss from Haag Nunataks with zircon U-Pb age of~1238 Ma, indicating the development of Mesoproterozoic arc magmatism in West Antarctica. The other four blocks preserve the geological records since~500 Ma. During the Paleozoic, the Ellsworth-Whitmore Mountains block was formed in a rapidly subsiding continental rift basin environment which was related to the back-arc extension caused by the Ross Orogeny, and the magmatic activity was rare. A set of convergence-related magmatism occurred in the middle to late Paleozoic in Mary Byrd Land block, which was formed in an active continental margin environment. The Antarctic Peninsula-Thurston Island blocks record the development of the Carboniferous-Permian arc during this time. During the Mesozoic, the tectonic setting of these blocks began to differentiate since the Jurassic. The Ellsworth-Whitmore Mountains block records Jurassic intra-plate magmatism, which may be associated with large igneous province. In Marie Byrd Land, the lithology changed from Ⅰ-type arc magmatic rocks to A-type alkaline magmatic rocks in the Jurassic-Early Cretaceous to the mid-Cretaceous period. This reflects a major change in tectonic setting from subduction to rifting during the mid-Cretaceous. The Jurassic-Cretaceous flare-up in arc magmatism record on the Antarctic Peninsula-Thurston Island blocks with a pulse of Jurassic large igneous provinces. These are the product of the interaction of continuous subduction and rifting. The Cenozoic magmatism was represented by the Antarctic Peninsula block with arc magmatism continuing until the Eocene. The temporal and spatial distribution of the arc magmatism was related to the subduction and collision of spreading ridge which was cut into several segments by sinistral transform faults.