Formation Environment and Genesis of the Oncolite in Lower Cretaceous Liupanshan Group of Liupan Mountain Area

• 责任者：Zhong Fuping (Guangzhou Institute of Geochemistry ; Chinese Academy of Sciences ; Guangzhou 510640 ; China) ; Zhong Jianhua
• 刊名：Acta Petrologica et Mineralogica
• 出版年：2010
• 卷期：29(2)
• 关键词：核形石 ; oncolites ; 沉积环境 ; sedimentary environment ; 六盘山 ; Liupan Mountains
• 页码：p.206-212
• 图表：4 illus., 1 table, 17 refs.
• 分类号：0803
• issnNo：ISSN1000-6524
• isbnNo：CN11-1966/P

Oncolites were found in Lower Cretaceous Naijiahe Formation of Liupanshan Group in a tunnel of Sikouzi Reservoir in the Liupan Mountain. A study of their external core and lamination characteristics suggests that they were formed mainly in a turbulent and high-energy water-environment. CaO content of concolites reaches 48.18%, indicating  obvious effect of the capturing and adhesion of calcium carbonate particles. Calcified algae itself and in situ precipitation of micro-organisms might also have been the causes for the formation of these concolites. In the study area concolites were formed in a high salinity, high temperature, hot and strong evaporation arid environment. A study of the formation environment of these oncolites in Liupanshan area shows that their formation environment was consistent with the tectonic setting at that time.