西南极南设得兰群岛中新生代地层特征

南设得兰群岛是晚中生代以来古太平洋板块向南极板块俯冲消减过程中形成的，目前对整个群岛的地层特征及沉积演化无统一认识。通过归纳总结国内外研究成果，认为该群岛出露的地层具明显的时空规律。群岛主体的西南部出露上侏罗统-下白垩统，发育海底扇、深海、斜坡裙、扇三角洲等沉积相，相伴随的火山作用主要为钙碱性玄武岩和玄武安山岩的喷发，记录了弧前盆地-火山岛弧的演化过程；群岛主体的东北部主要出露上白垩统-下渐新统，其中上白垩统-始新统发育一套玄武质熔岩、火山碎屑-沉积岩建造，为温暖气候下的陆相沉积，火山活动具有岛弧拉斑玄武岩与钙碱性火山岩的过渡性质。渐新统-下中新统则记录了从间冰期正常海相到冰期冰海相沉积的转变过程。

STRATIGRAPHIC CHARACTERISTICS OF THE MESOZOIC-CENOZOIC IN THE SOUTH SHETLAND ISLANDS, ANTARCTICA

South Shetland Islands is a magmatic arc formed in the subduction of the palaeo-Pacific plate beneath Antarctic Plate since late Mesozoic. Due to the subduction, the distribution of strata is rather regular in time and space. The exposing strata in southwestern South Shetland Islands is mainly the upper Jurassic- lower Cretaceous, The types of sedimentary facies are submarine fan, deep sea, marine slope apron, fan delta, and so on. The volcanism is manifested by eruption of alkaline basalt and basaltic andesite. It has recorded the evolution from fore-arc basin to volcanic islands. While the strata in northeastern South Shetland Islands is mainly upper Cretaceous to Neogene. The sedimentary environment of the upper Cretaceous-Eocene is continental basin in warm climate, which consist mainly of basaltic lava, pyroclastic debris and sedimentary rock. The volcanics are transitional from alkaline basalt to tholeiite in geochemistry. The Oligocene- Miocene has recorded the transformation from normal marine facies in interglacial stage to glacio-marine facies in glacial stage.