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PAN-AFRICAN EVENT AND FORMATION OF GONDWANA

泛非事件和冈瓦纳大陆的形成

基本信息

批准号：
09041116
负责人：
SHIRAISHI Kazuyuki
金额：
$ 9.47万
依托单位：
NATIONAL INSTITUTE OF POLAR RESEARCH
依托单位国家：
日本
项目类别：
Grant-in-Aid for international Scientific Research
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1999
项目状态：
已结题

项目摘要

This collaborative study between South Africa and Japanese geologists who had been studying in the East Antarctica aims to investigate the crustal formation during Neoproterozoinc to early Cambrian and reveal the Pan African orogeny related to the formation of Gondwana. During the three years program we investigated many parts of South Africa. In particular, the Grenvillian Natal-Namaqualand Belt extending around the southern and southwestern margins of the Kaapvaal Craton of South Africa was throughly investigated. This Province connects with the Dronning Maud Land in the Antarctica and the Grenville Province of the North America. Sr and Nd isotopic studies obtained various formation ages and model ages of the granitic and metamorphic rocks from the Namaqualand area. The isotopically juvenile Tugela terrane, part of the Natal belt, consists of a heterogeneous assemblage of regionally metamorphosed mafic and felsic rocks. The Tugela terrane is divisible on the basis of lithology and structural style, from east to west, into four major thrust sheets. The lithologically and geochemically distinct thrust sheets that comprise the oceanic Tugela terrane were each derived from distinct tectonic settings. The Kotongweni tonalite and its wall rocks, preserved in the Tugela sheet, provide a record of middle Proterozoic magmatic arc development prior to the obduction of the Natal belt onto the Kaapvaal craton at about 1.1 Ga. In addition, we have obtained some "new" mineralogical and petrological data in the metamorphic rocks from the Proterozoic Natal-Namaqualand Mobile Belt and Archean Limpopo Mobile Belt. The comprehensive results obtainted through this study will be published in a Memoir of the National Institute of Poal Research in 2001.

南非与在东南极研究的日本地质学家合作开展的这项研究旨在研究新元古代至早寒武世的地壳形成，揭示与冈瓦纳大陆形成有关的泛非造山带。在三年的计划中，我们调查了南非的许多地方。特别是，Grenvillian Natal-Namaqualand带延伸到南非Kaapvaal山脉的南部和西南边缘。该省与南极洲的德龙宁毛德地和北美的格伦维尔省相连。Sr和Nd同位素研究获得了纳马夸兰地区花岗岩和变质岩的各种形成年龄和模式年龄。同位素幼年Tugela岩是纳塔尔带的一部分，由区域变质镁铁质岩和长英质岩的异质组合组成。根据岩性和构造样式，Tugela盆地从东到西可分为四个主要的逆冲岩席。构成大洋图格拉火山岩的岩石学和地球化学特征不同的逆冲岩席分别来自不同的构造环境。Tugela幅中保存的Kotongweni英云闪长岩及其围岩记录了大约1.1 Ga时纳塔尔带向Kaapvaal克拉通逆冲前中元古代岩浆弧的发育。此外，我们还在元古宙纳塔尔-纳马夸兰移动的带和太古代林波波移动的带的变质岩中获得了一些“新的”矿物学和岩石学资料。通过这项研究获得的综合结果将于2001年在国家Poal研究所的一份备忘录中发表。