EVOLUTION OF GONDWANA - THE ANTARCTIC PERSPECTIVE WITH SHRIMP GEOCHRONOLOGY

东南极洲的印度板块德龙宁-毛德地被称为泛非莫桑比克移动的带的南延，是研究冈瓦纳大陆地壳演化的最佳场所之一。本研究的目的是利用变质作用P-T轨迹结合SHRIMP精确年龄数据重建冈瓦纳大陆的构造模式。主要结果如下：（1）纳皮耶杂岩由3.8-2.6 Ga的地壳碎片组成，最后一次造山运动在2.52-2.46 Ga的超高温变质作用中结束。（2）对Lutzow霍尔姆杂岩的变质年龄和原岩年龄的重新研究，阐明了前冈瓦纳历史与Sor Ronnian山脉的历史完全不同。此外，在Sor Ronaldo山脉，泛非事件的两个阶段得到确认。这些事实对冈瓦纳大陆的构造历史提供了制约。3）在中部德龙宁毛德地，通过变质作用模式的比较，提出内陆山区与希尔马赫丘陵属于不同的构造单元，4）对南非纳塔尔带中零星产出的格伦维尔晚期A型花岗岩体的SHRIMP年龄测定，揭示了该期花岗岩体形成的时间-5）利用格陵兰岛西南部的SHRIMP It Itsaq杂岩，苏格兰西北部的Harris杂岩，喜马拉雅山西部，越南的Kontum盆地和日本的日高带和甲府盆地。作为国家极地研究所开发和维护SHRIMP II研究的一部分，进行了U-Pb和Mn-Cr方法的标准化以及REE的测量。此外，还制备了杜卢斯联合公司的锆石标准样品。用常规U-Pb-Th同位素方法对新锆石标准进行了评价。

The Dronning Maud Land, which is the Indian sector of the East Antarctica is referred as the southern extension of the Pan-African Mozambique mobile belt, and is one of the best fields to elucidate the evolution of the Gondwana continental crust. The aim of this study is to reconstruct the tectonic model of the Gondwana using the meamorphic P-T paths combined with precise age data by SHRIMP. The major results are:1) The Napier Complex consists of crustal fragments formed during 3.8-2.6 Ga, and the last orogeny was terminated in 2.52-2.46 Ga with the ultra-high temperature metamorphism.2) Re-examination of the metamorphic and protolith ages of the Lutzow Holm Complex elucidated that the pre-Gondwana history is totally different from those in the Sor Rondane Mountans. Moreover, in the Sor Rondane Mts., two stages of the Pan-African events are recognized. These facts give the constraints far the tectonic history of the Gondwana3) In the central Droning Maud Land, it is suggested that the inland mountain area and the Schirmacher Hill belong different tectonic units by comparison of modes of metamorphism, plutorism and preliminary SHRIMP ages.4) The SHRIMP age dating for the late Grenvillian A-type granite bodies sporadically occurring in the Natal Belt of South Africa revealed the time-space transition of the igneous activity.5) Studies on the continental crust of many areas from the world were performed as collaboration work using SHRIMP It Itsaq Complex in SW Greenland, the Harris Complex in NW Scotland, western Himalaya, the Kontum massif in Vietnam and Hidaka Belt and Kofu basin in Japan.6) As a part of the study of the development and maintenance of the SHRIMP II at the National Institute of Polar Research, standardization of the U-Pb and Mn-Cr methods, and measurement of REE were performed. In addition zircon standard samples from Duluth Complex was prepared. New zircon standards were evaluated with the conventional U-Pb-Th isotope measurement.