西南极乔治王岛北海岸火山岩的~（40）Ar／~（39）Ar和K-Ar年龄测定

本文采用４０Ａｒ／３９Ａｒ、Ｋ－Ａｒ和激光微区等时线方法，对乔治王岛北海岸的火山岩进行了系统的年龄测定。实验结果表明，该区的火山活动从晚白垩世延续到始新世末期，主要喷发时代为始新世。岩石的年龄由南西向北东依次变新，表明乔治王岛的火山活动中心在不断迁移，与整个南设得兰群岛火山岩的时、空分布规律相符。侵入岩比火山岩生成晚而岩石化学成分更偏酸性，说明侵入岩可能是火山岩同源岩浆分异演化的产物。这批高质量数据的获得，将为区域火山岩地层时代的厘定和构造岩浆演化过程的研究提供有力的依据。

40 Ar/ 39 Ar AND K Ar DATING OF THE VOLCANIC ROCKS FROM THE NORTHERN COAST OF KING GEORGE ISLAND, WEST ANTARCTICA

The volcanic and intrusive rocks from the northern coast of King George Island have been firstly dated with 40 Ar/ 39 Ar dating technique, K Ar dilute and laser microarea 40 Ar/ 39 Ar isochron dating techniques. Systematically dated results provide that the volcanic activities in studied area lasted from Late Cretaceous to the end of Eocene epoch and the major eruptions occurred in Eocene. Northeastwards younging of rocks along the northern coast suggests a gradual migration of the volcanic centers in King George Island, which correspond to the regularly distributed time space pattern of the volcanic activities on the South Shetland Islands. The intrusive rock was formed later than the eruptive rocks, that implies the granodiorite was from the same magma resource as basaltic lava and underwent differentiation. These new datawith such high precision will give a great support either for collating and stipulating the stratigraphical time or to the research on tectonomagmatic process.