南极乔治王岛柯林斯冰帽冰芯（SDT）中火山物质成分特征

The Composition of Volcanic Ash from Ice Core of Collins Cap,King George island of Antarctica

对柯林斯冰帽小冰穹冰芯中物质成分的研究，发现冰芯中有九层火山灰沉积。它们由玻屑（橙玄玻璃）、岩屑（黑色）和晶屑（长石、辉石、橄榄石和微量的钛铁氧化物）组成。长石为钠钙系列的中长石到拉长石。橄榄石为镁质的贵橄榄石。主要元素和微量元素分析结果表明，该类火山灰为玄武质成分，其ＳｉＯ２含量在５０ｗｔ％左右，Ｎａ２Ｏ大于Ｋ２Ｏ，并具有轻稀土元素轻微的富集、重稀土元素亏损、Ｅｕ正异常的特征。这些火山灰的存在，证实了近百年来南极地区的企鹅岛和欺骗岛的火山喷发活动。

According to our study,there are nine layers ot volcanic ash deposited in ice core of small dome from Collins cap,King Creorge Island of Antarctica.These volcanic ashes consist of black color volcanic detritus,yellow volcanic glass and crystal mineral that are plagioclases,clinopyroxenes,olivine and a few of amphiboles, Ti-Fe oxides. The plagioclases belong to albite-anorthic series(An=33～55). Olivine is chrysolite type (Fo= 70～74). Major elements and trace elements analyses of volcanic ashes suggest that they are tholeiite with richer soda and lower potassium features. The REE distribution patterns of these ashes show light REE enriched type. Characteristics of expending mineral chemistry and geochemistry indicate that the ice core has a record of volcanic activity event nearly 100 years in Deception island and Penguin island of southwest Antarctica.