“江南造山带”变质基底形成的构造环境及演化特征  

Tectonic Environment of the Metamorphosed Basement in the Jiangnan Orogen and Its Evolutional Features

作　　者：王自强[1] 高林志[2] 丁孝忠[2] 黄志忠 

机构地区：[1]中国地质大学(北京),北京100083 [2]中国地质科学院地质研究所,北京100037 [3]江西省地质调查院,南昌330201

出　　处：《地质论评》2012年第3期401-413,共13页Geological Review

基　　金：科技部科技基础性工作专项(编号2011FY120100);中国地质调查局地调项目(编号121201011120131)的成果

摘　　要："江南造山带"变质基底的形成和演化长期存在不同认识。本文试图通过区域地层对比、火山—沉积组合、构造变形特征,大量新的测年数据以及淡色花岗岩(MPG)和含堇青石花岗闪长岩(CPG)等岩体的分布及产出的构造环境分析,再次探讨"江南造山带"变质基底的构造环境和演化特征。笔者等认为"江南造山带"变质基底的形成和演化与1.1～0.9Ga的"格林威尔运动"无关,它是Rodinia超大陆裂解后的不同陆块(如扬子陆块、华夏陆块等)的大陆边缘沉积,经830～780Ma之晋宁运动期碰撞造山,进而构成新元古代中—晚期扬子古陆新的増生大陆边缘。晋宁期碰撞造山的特征是:在时间演化方面经历了早期初始强烈碰撞、挤压变形—松弛拉张接受不同规模裂陷盆地或裂谷火山—碎屑沉积—终期再碰撞演化过程;在空间变化方面则显示为构造环境的多样性。以湘、赣边界剪切断裂带和鄱阳湖—赣江剪切断裂带为界,形成三种不同的构造环境。湘黔桂代表的西部区段和赣西北代表的中部区段均为被动大陆边缘的陆—陆对接碰撞构造环境。但二者在挤压和拉张强度和规模的差别,导致两区段构造形态的不同。赣皖浙东部区段为活动大陆边缘具多列岛弧及弧后盆地的洋—陆俯冲—碰撞构造环境。There are many different ideas about the forming and evolution of the metamorphosed basement of the ＂Jiangnan Orogen＂. This paper tries again to discuss its tectonic types and evolution features, based on regional stratigraphic correlation, volcanic-sedimentary assemblages, teetono-deformation, a large amount of isotopic dating in recent years, the distribution of magmatic rocks and analysis of tectonic environments of muscovite-peraluminous granite （MPG） and eordierite-peraluminous granodiorite （CPG）. The writers consider that the ＂Jiangnan Orogen＂ can not correlated with the 1100 -950 Ma ＂Grenvillian Orogen＂ in the formation of the metamorphosed basement and its tectonic evolution. It was the deposits of the continental margin of different blocks （ e. g. Yangtze Block and Cathysia Block） after Rodinia Super continent was broken up. They underwent 820 - 780 Ma ＂regional＂ Jinningian movement and reformed the Middle and Late Neoproterozoic continental margin of the Yangtze Oldland. The feature of the ＂Jinningian Orogen＂ are as follows ： （ 1 ） in evolution, it had a strong collision in early stage; then extrusion deformation--relaxation and extension formed different rift basins or rift elastic-- volcanic deposits ; finally re - collision. （2） In region, it was bounded by shear faults of Hunan--Jiangxi provinces and Poyang Lake--Ganjiang River. The metamorphosed basement of the ＂Jiangnan Orogen＂ was formed by three different tectonic environments; a collision of continent to continent of the passive continent margin was formed in the western part （Hunan, Guizhou and Guangxi ） and the middle part （northwestern Jiangxi ）. However, the difference between them in extrusion and extension led to the different tectonic forms. The tectonic environments from active continental island arc and back-arc basins to oceanic -continental subduetion collision are the features of the eastern part （Jiangxi, Anhui and Zhejiang Province）.

关 键 词：“江南古陆”变质基底 扬子陆快 华夏陆块 淡色花岗岩 大陆边缘 

分 类 号：P542[天文地球—构造地质学]