Process of crustal formation of the Rayner Complex, Enderby Land, East Antarctica

东南极洲恩德比地雷纳复合体的地壳形成过程

• 批准号: 08640584
• 负责人: SHIRAISHI Kazuyuki
• 金额: $ 1.09万
• 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 Scientific Research (C)
• 财政年份: 1996
• 资助国家: 日本
• 起止时间: 1996 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08640584/
• 关键词: East Antarctica; Geochronology; TTG; Napier Complex; SHRIMP; Gondwana; Ultra-high temperature metamorphism; continental crust; レイナ-岩体; セルロンダーネ; 変成作用; イオンマイクロプローブ; East Antarctica; Geochronology; TTG; Napier Complex; SHRIMP; Gondwana; Ultra-high temperature metamorphism; continental crust; レイナ-岩体; セルロンダーネ; 変成作用; イオンマイクロプローブ

The correspondence between metamorphic P-T path and geochronology is the most important issue on the discussion of the formation and evolution of continents. Enderby Land in East Antarctica is the one of the suitable areas for this study. This study aims re-examination of the geological framework in the Enderby Land and it's vicinity. The results would constrain the formation of the supercontinets in Precambrian, particularly it is expected to reveal the Grenvilian event, the world-wide orogeny in the middle to late Proterozoic. Following results have been obtained so far ; 1) The Rayner Complex and the Lutzow-Holm Complex (LHC) show similar metamorphic history of the clockwise retrograde P-T paths. 2) Tonalitic rocks in the Sor Rondane Mountains and metatrondjhemite in LHC have similar geochronological and geochemical characteristics. The petrogenesis for these p.lutonic rocks is interpreted by the melting of hot slabs which were transformed into garnet amphibolite. 3) Detailed petrographic study on the sapphirine-and osumilite-bearing paragenesis in the Napier Complex revealed that the physical condition of ultra-high temperature metamorphism reached more than 1000C and 7-8 kbar. Moreover, two-stage P-T paths were found, suggesting the intrusion of hot pluton into the middle crust as the heat source.

变质P-T路径和地质学之间的对应关系是讨论大陆形成和演变的最重要问题。南极东部的Enderby Land是这项研究的合适区域之一。这项研究旨在重新检查Enderby Land及其附近的地质框架。结果将限制前寒武纪中超强的形成，尤其是预计它将揭示Grenvilian事件，这是中间至晚期的全球造山学。到目前为止，已经获得以下结果； 1）Rayner复合物和Lutzow-Holm复合物（LHC）显示出顺时针逆行P-T路径的变质史。 2）Sor Rondane山脉和LHC中的Metatrondjhemite中的音调岩石具有相似的年代学和地球化学特征。这些扁豆岩石的岩化作用是通过转化为石榴石闪石的热板的融化来解释的。 3）关于纳皮尔复合体中sapphirine和含苏木岩的副膜片的详细岩石学研究表明，超高温度变质的物理状况达到了1000c和7-8 kbar。此外，还发现了两阶段的P-T路径，这表明热岩石作为热源侵入中壳。