摘要
靖远—白银地区白垩系见大型板状交错层理,层系厚3~5m 以上,细层厚5cm,倾角30°~32°,向下收敛,具风成砂岩特征.砂岩呈桔黄色,粒度0.125~0.5mm 者呈园状,粒度单峰态.薄片粒度分析作出的概率图为双跳跃总体,斜率高,分选好.用萨胡公式判别也为风成砂.显微镜下及扫描电镜下,砂粒的许多特征也都代表了大陆性干旱沙漠环境的产物.
The sandstones exposed at Jingyuan-Baiyin district show largescaletabular cross-bedding with over 3~5m-thick cosets and 5cm thick laminas,it has the angle 30°—32°and evidently converges downward.Allthese characteristics suggest the aeolian sandstons.The aeolian sandstones are orange(colour),round,0.125~0.5mm grainsize.They display one-peak size distribution.The probability curve mapsize analysis on thin section is almost totally composed of two-saltationpopulation with high incline rate which indicates high sorting index.The sandstones can also be distinguished as aeolian sands by Sahu form-ula.Many features of the sands under mic.and SEM present themselvesas caused by continental environment of arid desert.
出处
《兰州大学学报(自然科学版)》
CAS
CSCD
北大核心
1989年第4期113-117,共5页
Journal of Lanzhou University(Natural Sciences)
关键词
白垩系
风成砂岩
aeolian sandstone
cretaceous system