【摘要】 冈瓦纳古陆的研究已经有百年历史 ,而东南极又成为冈瓦纳研究的热点地区之一。在东南极拉斯曼丘陵地质考察与构造热年代学研究的基础上 ,中国科学家成为国际上最早一批阐明冈瓦纳古陆 ,特别是东冈瓦纳陆块形成于 5亿年前的“泛非”期构造运动的科学家。通过南极内陆格罗夫山地质调查 ,查明格罗夫山主要出露高角闪岩相—麻粒岩相深变质岩 ,岩石化学特征显示紫苏花岗岩、花岗质片麻岩和花岗岩属铝质A型深成岩系列 ,而长英质和镁铁质麻粒岩则来自岛弧、洋岛和洋中脊环境的表壳岩系列。测区以低角度面理构造为主 ,局部出现强剪切变形带。韧性变形可分为 3个阶段 :D1与前泛非期的构造事件有关 ,D2 相应于区域性麻粒岩相变质作用 ,D3 则可能反映泛非期造山作用后期的伸展作用。变质反应结构多显示为简单的区域性麻粒岩相变质作用 ,但镁铁质麻粒岩可鉴别出 3个阶段 :M1的温压条件为 80 0℃ ,9.3× 10 5Pa ;M2 为 80 0 - 810℃ ,6 .4×10 5Pa ;M3 仅 6 5 0℃。代表性花岗质片麻岩的锆石U Pb的离子探针分析显示峰期变质年龄集中于5 2 9± 14Ma ,花岗岩侵位年龄 5 34± 5Ma ,细晶岩脉年龄 5 0 1± 7Ma ,属于“泛非”期构造热事件。这些地质新证据显示在东南极内陆存在着一条从普里兹湾、格罗夫山到南查尔斯王子山?更多还原

【Abstract】 It is more than a century that the research on the Gondwana Super Continent remains,in which the East Antarctica Shield is one of the "hot point" regions.Based on the field investigation and thermal-tectonic chronological analyses,Chinese scientists have proposed,as first range in the world that the Gondwana Land,especially the East Gondwana Continent has been formed in the Pan-African aged orogen(～500 my).After the geological survery in the Grove Mountains,it is clear that the Grove Mts.consist mainly of a series of high-grade(upper amphibolite to granulite facies)metamorphic rocks.Geochemical analysis demonstrates that the charnockite,granitic gneiss and granite were belong to aluminous A type plutonic rocks,thus the felsic and mafic granulite were from supracrustal as island arc,oceanic island and middle oceanic ridge basalt.A few high-strained shear zones disperse in regional stable sub-horizontal foliated metamorphic rocks.Three generations of ductile deformation were identified,in which the D 1 is related to the event before Pan-African age,D 2 corresponds to the regional granulite peak metamorphism,whereas D 3 reflects ductile extension in late Pan-African orogenic period.The metamorphic reactions from granitic gneiss indicate a single granutite facies event,but 3 steps were disinterred from mafic granulite,with P-T condition of M 1 800℃,9 3×10 5Pa;M 2800±810℃,6 4×10 5Pa;and M 3 650℃.The U-Pb age data from representative granitic gneiss indicate(529±14)Ma of peak metamorphism,and (534±5)Ma of granite emplacement,and (510±7)of post-tectonic granodioritic veins.All these evidences suggest a huge Pan-African aged mobile belt inside of East Antarctica Shield extending from Prydz Bay via Grove Mountains to the southern Prince Charles Mountains,bisecting the East Antarctic Craton which was thought stable since 1000 Ma.This orogenic belt could link with the Tibet Block(Qiang Tang Plateau) in north,being another major suture during the Gondwana Land assemblage.更多还原