摘要
松辽地区西部斜坡英台地区姚家组二、三段,是在干旱一半干旱、源近流短、东倾陡坡背景下,在洪积扇前,由辫状河入湖形成的辫状河三角洲沉积。可明显区分出狭窄的辫状河三角洲平原,河口坝不太发育的辫状河三角洲前缘和夹浊积砂的辫状河前三角洲三种沉积亚相。辫状河三角洲平原由灰色含砾砂岩,粗、中砂岩,少量细砂岩,粉砂岩夹紫红色泥岩组成。具有明显的正韵律为特征。辫状河三角洲前缘沉积为灰色-绿灰色中、粗砂岩、细砂岩、少量的含砾砂岩,成正韵律或反韵律夹在灰绿色、灰黑色泥质岩中。辫状河前三角洲沉积多为灰绿色、灰黑色泥质岩,可夹少量砂质浊积岩。上述沉积特征明显地区别于正常河流三角洲沉积和扇三角洲沉积。
The braided Streamdelta deposits of Y2+3 member in Yingtai area of west slope of Songliao Basin were formed in front of pluvial fan by braided stream entering lake with the characteristics of dry and half dry climate, proximal sediment source and short steam and steep slope to the east. It can obviously be divided into three kinds of sedimentary facies: the delta plain of the narrow braided stream, the delta front of the braided steam whose channel-mouth bars are not delopment and the prodelta of the braided steam in which turbidite sandstone are interspersed. The delta plain of braided steam consists of gray gravel-bearing sandstone, coarse-grained and medium-grained sandstone, a little of fine - grained and siltstone in which purplish red mudstone is interspersed, it owes to the obvious normal rhythm features. The delta front of braided steam has the normal or inverse rhythm feature of gray, green gray medium-grained and coarse - grained sandstone, fine - grained sandstone and a little of gravel-bearing sandstone intcrspered in gray green, gray black argillaceous. The prodelta of braided steam consists of gray green, gray black argillaceous and a little of sandy turbidite. Above - mentioned sedimentary features can obviously be used to distinguish normal steam delta with fan delta deposits.
关键词
松辽盆地
三角洲
沉积特征
Songliao Basin
braided river
delta
sedimentary features.
