| 翻訳と辞書 |
| Dharwar Craton ： ウィキペディア英語版 |
Dharwar Craton
The Dharwar Craton in South India presents a natural cross-section of late-Archaean continental crust. There are three main structural zones: a root zone of highly heterogeneous petrology (from monzonite to granite) and texture (phenocryst accumulation), a "channel zone" where evidences of large scale magma ascent can be observed, and a zone of superficial intrusions, consisting in independent homogeneous intrusive bodies. In the root zone, mantle-derived magma underwent fractional crystallisation which was followed by mingling between the residual liquids and melts generated by anatexis of the surrounding gneissic basement.
The term Dharwaar Supergroup is now used as synonymous with metamorphosed Archaean sediments and including all the schistose series below the eparchaean unconformity. The Dharwarian rocks are mostly unfossiliferous.
==Lithology of the Dharwars==
The rocks of this age show extremely complex nature with clastic and chemically precipitated sediments, volcanic and plutonic rocks - all of which show varying degrees of metamorphism. The majority of the rocks are often phyllites, schists and slates. There are hornblende-, chlorite-, haematite-, and magnetite- schists, felspathic schists: quartzites and highly altered volcanic rocks, like rhyolites and andesites turned into hornblende-schists; abundant and widespread granitic intrusions; crystalline limestones and marbles; serpentinous marbles; steatite masses; beds of jaspers and massive beds of iron and manganese oxides.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
■ウィキペディアで「Dharwar Craton」の詳細全文を読む
スポンサード リンク
| 翻訳と辞書 : 翻訳のためのインターネットリソース |
Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.
|
|