吉林南部老岭群的原岩恢复和古沉积环境

PROTOLITH RECOVERING AND PALEOSEDIMENTARY ENVIRONMENT OF LAOLING GROUP IN SOUTHERN JILIN PROVINCE

吉林南部地区老岭群划分为下亚群大东岔组、临江组和大栗子组,上亚群石青沟组和珍珠门组.老岭群原岩主要类型为泥岩、砂岩、粉砂岩、粉砂质黏土岩、泥砂质岩、石英砂岩、白云质黏土岩及杂砂岩等,均具有明显的沉积特征.分析显示吉南地区的古沉积环境变迁与海平面的升降旋回对应,分别经历了下亚群临江期高能滨海相,大栗子组低能浅海相、浅海陆棚相、半封闭湖相到高能的潮坪环境沙坪相过渡,以及上亚群石青沟组高能滨海相到低能半闭塞台地相的过渡,珍珠门组经历了由低能半闭塞台地相、开阔台地相到高能台地边缘相,再到低能浅海陆棚相的过渡.

Laoling group in Southern Jilin Province can be divided into lower subgroup（including Dadongcha formation,Linjiang formation and Dalizi Formation）and upper subgroup（includint Shiqinggou and Zhenzhumen formations）.The main protolith types of Laoling group are mudstone,sandstone,siltstone,silty claystone,pelitopsammite,quartz sandstone,dolomitic claystone and apogrit,which were formed in sedimentary environment.The paleosedimentary environment experienced high energy offshore facies during Linjiang formation,low energy neritic facies,neritic-continental shelf facies,semi-closed lagoon facies and high energy sand flat facies in Dalizi formation,high energy offshore facies and slow energy semi-closed platform facies in Shiqinggou formation,low energy semi-closed platform facies,open platform facies,high energy platform margin facies,and low energy neritic-continental shelf facies in Zhenzhumen formation.The analysis shows that the change of paleosedimentary environment was corresponding with that of the eustatic sea level.