摘要
根据采自松潘-阿坝和西秦岭地区的约180件三叠系砂岩样品的薄片观察和统计,利用Dickinson三角图解对其物源区背景进行了判别,在此基础上对三叠纪原型盆地性质进行了探讨。松潘-阿坝和西秦岭三叠系复理石砂岩以岩屑长石杂砂岩和长石岩屑杂砂岩为主,具有高杂基含量、低成分成熟度和低结构成熟度的特点,物源主要来自于碰撞造山带。若尔盖坳陷北部与洮河坳陷物源区相似,碎屑主要来自过渡再旋回、切割弧及二者的混合区,大洋物质多于大陆物质,显示源区具有成熟度和稳定度较差到中等构造背景。若尔盖坳陷南部和马尔康坳陷北部物源主要来自石英再旋回;但大洋物质少于大陆物质,源区具有成熟度和稳定度较高的构造背景。中三叠世拉丁晚期到晚三叠世卡尼期,松潘-阿坝地区为一残余海盆,向其提供物源的是北侧的东昆仑-秦岭造山带、东侧的大别造山带和东南侧的扬子古陆。
The Songpan-Ganzi fold belt of central China is situated at the junction of the North China Block, the Yangtze Block and the Qiangtang Block, bounded to the north by the East Kunlun and West Qinling orogenic belts, to the southwest by the Jinshajiang suture belt and to the east by the Longmenshan thrust belt, covering a huge triangular area of more than 0.2 × 10^6 km^2. The Songpan- Ganzi fold belt comprises the deformed and partially metamorphosed Middle to Late Tirassic flysch with a great thickness of more than 5 kin. One hundred and eighty sandstone samples from the Triassic flysch in Songpan-Aba and West Qinling areas are checked under microscope to analyse of their detrital modes and evaluate their provenance and the tectonic setting in which they deposited by using the Dickinson triangular plots. The sandstones are mainly feldspathic greywacke and lithic greywacke with low compositional and textural maturities, and they are mainly derived from collisional orogenic belt. The provenances of sandstones from the northern Ruoergai depression are similar with those from the Taohe depression, and most detritus are plotted in the ranges of transitional recycled, dissected arc and mixed in the QmFLt plot, with more oceanic component than continental, suggesting these sandstones are mainly derived from provenance terranes related suture and collisional belt. The sandstones from the southern Ruoergai depression and the northern Maerkang depression are dominated by quartzose recycled origin, but with more continental component than oceanic, implying these sandstones are derived from continental block and/or foldthrust belt. During the middle to late Triassic （late Ladinian to Carnian）, the Songpan-Ganzi flysch basin was a remnant basin underlain by continental crust and was supplied from the Kunlun-Qinling orogenic belt in the north, the Dabie orogenic belt in the east and the Yangtze oldland in the southeast.
出处
《成都理工大学学报（自然科学版）》
CAS
CSCD
北大核心
2009年第5期465-474,共10页
Journal of Chengdu University of Technology: Science & Technology Edition
关键词
松潘-甘孜褶皱带
西秦岭
三叠纪
复理石
砂岩组分
物源
原型盆地
Songpan-Ganzi fold belt
West Qinling
Triassic
flysch
sandstone composition
provenance
prototype basin
