1:25万比如县幅、丁青县幅、嘉黎县幅、边坝县幅地质调查成果与进展

1:250 000 Biru, Dengqen, Lhari and Banbar Sheets in Xizang

关键词:  1:25万  地质调查  比如县幅  丁青县幅  嘉黎县幅  成果与进展  西藏

Key words:  1:250 000  geological survey  Biru Sheet  Dengqen Sheet  Lhari sheet  Banbar Sheet  development  Xizang

摘要:

在丁青蛇绿岩以西的色扎岩体顶部单元硅质岩中首次发现早侏罗世菊石化石;在丁青县雪拉山口南的雀莫错组、布曲组中新采获双壳、桦树等化石;在巴青县雅安大山雀莫错组、马里组板岩中新采获云雀贝化石;边坝县的多尼组可分为3套岩性组合,在灰岩中发现大量的双壳类化石,可望建立一个新的岩性地层单位;拉孜北凼木曲东岸的拉贡塘组碳酸盐岩应为一套多旋回凝灰岩,发现丰富的苏铁类和真蕨类植物化石,具有晚侏罗世至早白垩世植被面貌;在索县次汝乡北多尼组中新发现白云母花岗岩岩滴;将嘉黎断裂带南侧娘蒲乡至错高乡一带的原蒙拉组解体为4套地层,并在其中发现变质侵入体;新发现几处蛇绿岩。

Abstract:

There occur the Early Jurassic ammonites in the siliceous rocks from the top units of the Serca massif west of the Dengqen ophiolite zone, bivalves and Betula in the Qoimaco and Biqu Formations south of the Xuela Pass in Dengqen, and Alauda in the slates from the Qoimaco and Mali Formations in Ya'andashan, Baqen. Three lithologic associations may be discriminated in the Duoni Formation, Banbar, that is expected to be defined as a new lithostratigraphic unit where abundant bivalves appear in the limestones. The Lagongtang Formation carbonate rocks on the eastern bank of the Dangmu River in northern Lhaze should be considered as a succession of polycyclic tuff in which abundant plant fossils occur, including Cycas and Filicinae characteristic of the Late Jurassic to the Early Cretaceous vegetation features. The muscovite granite tears are identified in the Duoni Formation north of Ciru, Sog County. The formerly Mengla Formation in the Nyangbo-Conggo zone on the southern flank of the Lhari fault zone is redivided into four successions of strata, in which metamorphic intrusive rocks are hosted. There occur also ophiolites in several places.