1:25万喀纳幅、日土县幅地质调查成果与进展

1:250 000 Kana and Rutog Sheets in Xizang

关键词:  1:25万  地质调查  喀纳幅  日土县幅  成果与进展  西藏

Key words:  1:250 000  geological survey  Kana Sheet  Rutog Sheet  development  Xizang

摘要:

地层方面,重新厘定了地层区划界线并建立接奴群多仁组、日松组,发现了中晚志留世地层;厘定与划分了日干配错群,修订了欧利组并确定其时代,建立五峰尖组。岩石方面,建立侵入岩岩石谱系单位并划分构造-岩浆组合带;在南羌塘地区发现了海西期石英闪长岩石炭—侏罗纪地层中发现火山岩夹层及透镜体。构造方面,首次在班公湖-怒江带北侧划分出五峰尖-拉热拉新晚侏罗世—早白垩世陆缘火山岩浆弧带Ⅲ级构造单元,将班公湖蛇绿混杂岩带划分为北亚带和南亚带两个构造单元,基本查明了班公湖蛇绿混杂岩带的内部结构、物质组成及其边界断裂特征,探讨了班公湖-怒江结合带西段的弧-盆系时空结构,对班公湖地区中生代特提斯洋的演化规律作了系统总结。新发现一些矿产资源。

Abstract:

Stratigraphically, the redelineation of the stratigraphic boundaries resulted in the re-establishment of the Duoren and Risum Formations in the Jienu Group, Rigain Punco Group, Ouli and Wufengjian Formations. Petrologically, the lineage units are reconstructed for the intrusive rocks and the tectonic-magmatic belts are determined for the surveyed areas. There occur the Hercynian quartz diorite in southern Qiangtang, and volcanic interbeds and lenses in the Carboniferous-Jurassic strata. Tectonically, the Wufengjian-Larelaxin Late Jurassic-Early Cretaceous continental-margin volcanic-magmatic arc zone is discriminated as a third-order tectonic unit. The Bangong Lake ophiolitic mélange zone is subdivided into the northern and southern subzones. The former was emplaced during the Late Jurassic and the latter during the Late Cretaceous. The Mesozoic Tethyan Ocean in the Bangong Lake area has undergone the following stages of evolution:spreading during the Triassic to Early and Middle Jurassic, bidirectional subduction during the Middle and Late Jurassic, generation of a residual oceanic basin during the Late Jurassic to Early Cretaceous, southward subduction during the latest Early Cretaceous, and continent-arc (continent) collision during the Middle Cretaceous to Middle Eogene.