准噶尔盆地乌尔禾地区二叠系风城组盐类矿物和成因分析

二叠系风城组为准噶尔盆地乌尔禾地区重要的勘探层系,也是成因非常特殊的深湖相含盐火山-沉积建造。通过14口钻井岩心观察,296片薄片鉴定,30块扫描电镜和28件X衍射等分析技术手段,较为详细地研究了风城组盐类矿物及伴生矿物的各项特征,识别出硅硼钠石、碳酸钠钙石、白云石等主要盐类矿物和硬石膏、石膏、玉髓、黄铁矿和蒙脱石等伴生矿物,确定风城组深湖相含盐火山-沉积建造与同期相间发生的火山喷发和湖底热液喷流活动有关,其成因可与酒西盆地下沟组湖相喷流岩和东非裂谷坦噶尼喀湖现代深湖底热液喷流沉积作用相类比,提出"深水湖盆热液喷流含盐火山-沉积建造模式"。

SALT MINERALS AND THEIR GENESIS OF THE PERMIAN FENGCHENG FORMATION IN URHO AREA,JUNGGAR BASIN

In the Urho area of Junggar Basin,the Permian Fengcheng Formation is an important exploration stratam characterized by very special deep lake salt-bearing volcanic-sedimentary formation.Based on the core observation,thin section identification,scanning electron microscopy,X-ray diffraction and chemical analysis,a more detailed study was made on the characteristics of the salt minerals and their associated minerals in the Fengcheng Formation.Salt minerals in the Fengcheng Formation consist of reedmergnerite,shortite,trona,ankerite and associated with anhydrite,gypsum,chalcedony,pyrite and smectite.It was indicated that the Fengcheng Formation were related to the interphase volcanic eruption and lake hydrothermal exhalative activities in the same period.Their characters and genesis can be compared with the lacustrine exhalative rocks of Xiagou Formation in Jiuxi Basin and the modern deep lacustrine hydrothermal exhalative deposition in Tanga Nika Lake,East African rift Valley.Accordingly,a hydrothermal exhalative salt-bearing volcano-sedimentary mode in the deep lake basin was proposed in the paper.