摘要:
吉林省延边地区松江盆地早白垩世大拉子组地层非常发育,按照岩性组合特征,自下而上可分为砂砾岩段和含油页岩段。通过对大拉子组野外剖面、露头的岩石类型、粒度特征、原生沉积构造及古生物化石组合等研究,识别出冲积扇相、扇三角洲相、湖泊相及湖泊水下扇相4种沉积相和9种沉积亚相类型。平面上,冲积扇相主要发育于盆地东南缘头道沟以南地区、羊草沟—东南岔一带及盆地东北部;扇三角洲相主要分布在盆地周缘,在砂金沟—羊草沟以东、羊草沟—小沙河以南一带、小沙河西南部最为发育;湖泊相主要分布于盆地中部,老偏坡—东山—砂金沟—松江屯一线地区;湖泊水下扇发育于松江镇—砂金沟以北一带,东南岔南部地区也有分布。区内大拉子组沉积及演化明显受到区域构造活动、古地形、古气候和基准面变化等因素的影响和控制。大拉子组沉积早期发育冲积扇相和扇三角洲相,湖相分布局限,沉积物主要来自盆地东南部,沉积中心位于小沙河—新丰一带。中晚期盆地向南扩张,沉积中心迁移至杨木屯—胜利屯一带,湖相广泛发育,在半深湖—深湖区局部发育了湖泊水下扇相沉积。
Abstract:
It is typically developed Dalazi Formation stratigraphy of Early Cretaceous in Songjiang Basin of Yanbian region of Jilin Province. According to lithologic series, from bottom to top, the stratigraphy of Dalazi Formation is divided into sandstoneconglomerate sector and oilbearing shale sector. On the basis of the analyses of rock types of field sections and outcrops, grain features, primary sedimentary structure, paleontology fossil combination of Dalazi Formation, 4 sedimentary facies are recognized: luvial fan facies, fan delta facies, lake facies and lake subaqueous fan, with 9 sedimentary subfacies. Plan view, fluvial fan is mainly formed in the south of Toudaogou, southeast of Basin, the belt zone along Yangcaogou to Dongnancha and northeast of Basin; Fan delta chiefly occurs at the circum of Basin, the east of ShajingouYangcaogou and the south of YangcaogouXiaoshahe, and of which is much rich in northwest of Xiaoshahe; Lake facies mostly emergent at the center of Basin and the zone along Laopianpo, Dongshan, Shajingou, Songjiangtun; Lake subaqueous fan nearly concentrated in the zone north of SongjiangzhenShajingou, and some formed in the south of Dongnancha. The sedimentation and evolution of Dalazi Formation in Songliao Basin is obviously influenced and controlled by local tectonic activities, paleotopography, paleoclimate and baselevel change. Early of Dalazi Formation, the Basin developed fluvial fan and fan delta, but lake facies is confided .The deposit center located in the belt of XiaoshaheXinfeng and the sediments maily came from the northeast of the basin. After that, the basin expanded southwards, with deposit center moving to the zone of YangmutunShenglitun. The basin developed lake facies, with some lake subaqueous fans distributed in somewhere of moderate deep lake and deep lake.