摘要
本文对赤山组创名剖面的岩相及沉积环境进行了详细研究。赤山组为典型内陆盆地沙漠环境沉积物,具较复杂的层序结构,其下段主要为沙漠湖或干盐湖沉积,上段为风成沙丘沉积。对上段风成沙丘沉积系统内的不同级别边界面的特征及成因进行了描述分析;探讨了赤山组沉积的构造背景,认为是在干热气候条件下,苏北盆地已从断陷转为拗陷并逐渐封闭时的沉积物。
The sedimentological analysis of the Chishan Formation is the result of the detailed,bed - by- bed study of the standard profile of Chishan Formation in Chishan Mountain,Jurong County,Jiangsu.Considering lithologies are diverse and according to the genetic type,six recurring lithophases are distinguished as follows: Lithophase 1.Purplish red fine calcareous feldspathic graywacke. Lithophase 2.Purplish Ted fossiliferous calcareous clay siltite or silty claystone. Lithophase 3.Purplish red thin bedded silty clay dolomite(or dolomitic fine-silty sandstone) with polygonal fracture. Lithophase 4.Bricky red fine feldspathic quartz sandstone with large - scale and high - angle cross - bedding. Lithophase 5.Purplish red thick bedded medium - fine feldspathic quartz sandstone with plane bed lamination,intercalating muddy flate gravel conglomerate and thin bedded gravelstone. Lithophase 6.Bricky red lenticular unequigranular graywacke> fine feldspathic quartz sandstone and silty claystone,which consist of hemicycles with fining- upward grain size. The Chishan Formation can be subdivided into two members.The lower member consists dominantly of lithophases 1、2 and 3 which make up hemicycles.The upper member is mainly composed of lithophases 4、6.According to the features of the sedimentary structure and texture and lithophase associations of Chishan Formation,the sedimentary environment of the lower member is explained the desert lake or playa and the upper member interpreted aeolian desert sea. In this paper,it is discussed that the bounding surfaces within the aeolian sandstones with large scale and high - angle cross -bedding (lithophase 4),discribed the sedimentary characteristics of the first - order surfaces(Stokes surfaces) and inquired into the depositional tectonic setting of the Chishan Formation.We consider that the Late Cretaceous Chishan Formation formed during the periods from slowly thermal cooling subsidence to shrinking of the Subei Basin.
出处
《沉积学报》
CAS
CSCD
北大核心
1997年第A12期1-7,共7页
Acta Sedimentologica Sinica
基金
江苏省自然科学基金资助项目(编号BK95129207)
关键词
沉积环境
赤山组
晚白垩世
江苏
sedimentary environment
Chishan Formation
Late Cretaceous
Jiangsu
