四川大邑—崇州地区的白垩、第三系

THE CRETACEOUS AND TERTIARY SYSTEMS IN DAYI AND CHONGZHOU REGIONS, SICHUAN

四川大邑、崇州地区的白垩、第三系发育良好 ,地层呈北东—南西走向。在《万家坪幅》区域地质调研期间 ,对该区的白垩系、第三系测制了多条剖面 ,划分出了天马山组、夹关组、灌口组、名山组及大邑砾岩等岩石地层单元 ,总结了它的岩石特征相变情况 ,讨论了白垩、第三纪地的地质时代及划分对比 ,简述了这一时期沉积环境的演变是由冲积扇到河。

The Cretaceous and Tertiary Systems are well developed and strike NE—SW in the Dayi and Chongzhou regions, Sichuan. Some Cretaceous and Tertiary sections were surveyed in these regions during the mapping of the 1∶50000 sheet of Wanjiaping from 1997 to 1999. From these sections,four lithostratigraphical units, namely Tianmashan, Jiaguan, Guankou and Mingshan Formations,and one informal lithostratigraphical unit, namely Dayi Conglomerate was recognized.Their lithological characters and facies changes were summarized.The Cretaceous and Tertiary chronostratigraphy is discussed.The bases for the evolution of the depositionary environment from alluvial fan to fluviolacustrine facies are briefly described.