论文部分内容阅读
在青藏高原北羌塘盆地青海南部,青海省杂多县扎青乡地区的然者涌一带,发现以基性火山熔岩为主夹有中基性火山碎屑岩,具大陆板内裂谷拉斑玄武岩喷发特点的一套火山地层。该地层底部角度不整合接触覆盖在早中二叠世开心岭群诺日巴尕日保组、九十道班组之上,其上被晚三叠世结扎群甲丕拉组角度不整合覆盖。主要岩性为灰绿—灰紫色橄榄玄武岩、粗面玄武岩、玄武粗安岩及流纹岩、中基性火山角砾岩、角砾凝灰岩夹少量流纹岩和紫红色岩屑砂岩及细砾岩,其特征与峨眉山低钛玄武岩相似,具陆相喷发-沉积特征。区域对比在北羌塘地区具有独特地层特征,可与四川峨眉山玄武岩地层进行对比。而区域上该地区晚二叠世主要为一套海陆交互相含煤碎屑岩建造,未发现陆相火山岩出露,本文建立正式地层单位扎青组,以供参考,其时代暂归晚二叠—早三叠世。
In the northern Qiangtang basin of Qinghai-Tibet Plateau in southern Qinghai Province, Zhaogong Township, Zaoguang County, Qinghai Province, Ranch Chung area found foundations of basic volcanic lava are mainly composed of the basement pyroclastic rocks with continental plate rift pull A set of volcanic formations characterized by eruptive basalt. The unconformity contact at the bottom of the stratigraphic cover is covered by the unconformity of the Late Triassic ligation group Jiapila Formation over the Early Pleistocene Kaixilingling Group of Norriba Ga Rihibao and Jiuduansa Formation. The main lithology is gray-green-purple purplish-black basalt, rough basalt, basalt and rhyolite, medium-basic volcanic breccia, brecciated tuff with a small amount of rhyolite and purplish-red lithic sandstone and fine gravel Rock, which is similar to Emeishan low-Ti basalts and has continental facies-eruption-sedimentary features. Regional contrasts have unique stratigraphic features in the northern Qiangtang area, which can be compared with the Emeishan basalts in Sichuan Province. The Late Permian in the area mainly consisted of a set of sea-land interaction coal-bearing clastic rocks, and no continental volcanic rocks were found. In this paper, a formal formation unit Zhaqing Formation was established for reference. Overlaid - Early Triassic.