“大洋板块地层”的重建与意义——以藏南仲巴地区为例  

The reconstruction of oceanic plate stratigraphy and its implications: A case study of Zhongba area, southern Tibet

作　　者：魏玉帅[1,2] 李亚林[1,2] 陈曦[1,2] 王成善[1,2] 李祥辉[3] 李鑫[1] 钟瀚涏 

机构地区：[1]中国地质大学地球科学与资源学院,北京100083 [2]中国地质大学青藏高原地质研究中心,北京100083 [3]南京大学地球科学系,江苏南京210000

出　　处：《地质通报》2015年第10期1789-1801,共13页Geological Bulletin of China

基　　金：中国地质调查局项目(编号:1212011086037;1212011121229)

摘　　要：混杂岩是古增生楔存在的标志之一,一般由枕状玄武岩、灰岩、放射虫硅质岩、硅质页岩、砂岩等混乱无序组成。目前"大洋板块地层"(OPS)运用放射虫地层学方法对混乱的增生楔断片进行重建取得了良好效果,并清晰地展示了大洋板块俯冲和洋底物质连续增生的历史。在西藏仲巴地区填图过程中,结合放射虫年代学分析鉴定结果,以OPS重建的思路和理论作为指导,重建了仲巴地区混杂岩的大洋板块地层,并恢复了该区域特提斯洋在洋中脊大洋板块增生至消亡的岩石序列,自下而上分别为侏罗纪海山玄武岩、海山覆盖物侏罗系—白垩系碳酸盐岩、海山周围沉积的侏罗系—白垩系放射虫硅质岩和硅质页岩,以及海沟附近的白垩系陆源碎屑岩等,为特提斯洋大洋板块俯冲的方向、持续时间和古大地构造环境提供了信息。Melange generally consists of such chaotic blocks as pillow lava, limestones, radiolarian cherts, siliceous shales and sandstones, which tectonically contact with each other. Melange serves as a piece of evidence of the accretionary prism （AP） related to the subduction zones. Recently, by using radiolarian biostratigraphy, the theory of ocean plate stratigraphy （OPS） is referred to as an approach to the accretionary process of these blocks. In order to reconstruct the process of subduction and successive accretion of ocean floor material of Neo-tethys, the authors used the theory to mapping the accretionary prism related to the Yalung Zangbo suture zone in Zhongba area, southern Tibet. The OPS of AP in Zhongba area consists of Jurassic basalt of sea mountain, Jurassic- Cretaceous reefs on the sea mountain, the pelagic sediments such as siliceous shales and radiolarian cherts and the Cretaceous terrigenous clasts close to the trough. This study provides new information on the direction, duration and the tectonic settings of the subduction of the Neo-tethys Ocean.

关 键 词：放射虫硅质岩 海山 大洋板块地层 特提斯洋 仲巴 藏南 

分 类 号：P53[天文地球—古生物学与地层学] P56[天文地球—地质学]