义敦岛弧带多旋回演化的基本轮廓  

An Overview of the Multicyclic Evolution of the Yidum Island Arc Belt (Southwest China)

作　　者：姚华舟[1] 

机构地区：[1]中国地质科学院宜昌地质矿产研究所,443003

出　　处：《地质论评》1999年第S1期851-857,共7页Geological Review

基　　金：国家自然科学基金项目(编号49872015)资助

摘　　要：位于青藏高原东部边缘的义敦岛弧带,晚二叠世以来经历了伸展与挤压相交替的多旋回式构造演化。根据伸展、挤压交替的阶段性变化,其演化历程可划分为10期(阶段):①二叠纪—前二叠纪:泛扬子板块阶段;②二叠纪末—中三叠世早期:大陆边缘裂谷→海洋;③中三叠世晚期:不成熟岛弧;④早卡尼期:裂谷与海洋;⑤晚卡尼期—早诺尼期:成熟岛弧;⑥中—晚诺尼期:岛弧基底上的裂谷作用;⑦诺尼期末—瑞替期:弧陆碰撞和残留海;⑧侏罗纪—早白垩世:挤压褶皱造山;⑨晚白垩世—第三纪:山原裂谷作用和山间盆地;⑩第四纪—现代:快速隆起造山。二叠纪末—三叠纪初为本区构造格局的转折点,即本区脱离扬子板块主体部分向西漂移并导致产生新的洋壳,出现新的构造格局。三叠纪的构造伸展—挤压转换最为频繁,火山—沉积作用也最为活跃,以钙—碱性中酸性火山岩为代表的义敦火山弧形成于这一时期。The Yidun island arc belt, on the eastern margin of the Qinghai—Xizang Plateau and between the Jinshajiang fracture zone and Garze—Litang fracture zone, is a very important unit of the Sanjiang (Jinshajiang, Lancangjiang and Nujiang Rivers) fold system within the Tethyan tectonic realm. This area undergone a multicyclic evolution characterized by alternation of extension and compression regime, which could be divided into 10 stages. ①Permian and pre-Permian stage:being one part of the pan-Yangtze plate. At present, the Yidun island arc belt is far separated from the Yangtze landmass by the extensive Yajiang fold system, the marginal tract of the present Yangtze landmass. However, in the Permian and pre-Permian this area was directly connected with the present Yangtze landmass, forming a unified and broad plate, which could be called the pan-Yangtze Plate; ② Terminal Permian-early middle Triassic stage:marginal continental rift→ocean. In the terminal Permian the pan-Yangtze plate cracked and formed some land blocks such as Zhongza and Ruoergai blocks. These blocks drifted westward in the early-Early Middle Triassic and the oceanic crust initiated, forming the Garze—Litang ocean, which has its relics represented by a sequence of basic pillow lavas, basic-ultrabasic cumulates and radiolarian siliceous rocks exposed intermittently along the Garze—Litang fracture zone; ③late Middle Triassic stage:short-term's subduction of the Garze—Litang ocean and the appearance of the immature island arc in the Yidun area; ④Early Carnian stage: the rifting Yidun area and the spreading Garze-Litang ocean; ⑤late Carnian—early Norian stage:the thorough subduction of the Garze—Litang ocean and the forming of the Yidun mature island arc; ⑥middle—late Norian stage:rifting on the island arc; ⑦ Terminal Norian—Rhaetian stage:collision and relict sea; ⑧ Jurassic—Early Cretaceous stage: intensive compression and orogeny; ⑨ Late Cretaceous—Tertiary stage: intermontane rift—basin; ⑩Quaternary—tod

关 键 词：义敦岛弧带 多旋回演化 基本轮廓 

分 类 号：P588.14[天文地球—岩石学]