Abstract:

This paper give the outline of the volcanic geology and volcanism of Livingston Island,which is based mainly on the new data and new evidences gotten in recent years investigation and researches. The oldest volcanic stratigraphical unit is named Byres Formation,which consists of Late Jurassic to Early Cretaceous basalt,basaltic andesite lava,volcaniclastic,agglomerates and mudstone,siltstone outcropped at Byers Peninsula,the northwest part of Livingston Island. The Mount Bowles Formation of Cretaceous age is an altered volcanic strata,outcropped in the central part of Livingston Island and composed largely of andesitic lava with interbedded pyroclastic rocks. Both the interlayered volcaniclastic rock and lava at Hannah Point and the olivine basalt at Cape Shirreff have the same Middle Cretaceous ages. Dolerite is accumulated at Siddons Point which represents the typical products of Late Cretaceous volcanism. Combining with volcanic activities,Eocene hypabyssal rocks,tonalite,intruded in Cretaceous volcanic strata. Quaternary olivine basalt of Edinburgh Hill Formation occurred in the northern part of island. The spatial distribution of volcanic rocks and the migration of volcanic activities in Livingston Island with time is basically corresponded to that in South Shetland Islands. Petrographical,petrochemical and geochemical data show that the lavas of Byers Peninsula and Cape Shirreff and the dolerite at Siddons Point belong to calc alkaline series and with the characters of lower potassium and magnesium. The Early Tertiary tonalite,caring out the compositional features of olivine basalt and dolerite and being the product of Cenozoic volcanism in the South Shetland magma arc was formed at the late evolution stage of calc alkaline magma. The lavas of Mount Bowles Formation and from Hannah Point are distinguishable both in petrography and petrochemistry from that of other places,the presence of which is related not only to the arc volcanism but also to the distinctive tectonic setting where they formed. Pleistocene to Recent olivine basalt was derived from a primary magma,and the volcanism might be controlled by Late Cenozoic extensional or transtensional tectonics.