鲁西南二叠纪近海盆地缓坡三角洲沉积古地理演化

运用沉积学、岩石学的方法，结合野外露头实测与钻井观察，在鲁西南二叠纪近海盆地缓坡三角洲沉积中识别出6种岩相和8种沉积微相，其中6种岩相为灰黄色粗砂岩相（CS）、浅灰色中砂岩相（MS）、浅灰色细砂岩相（FS）、深灰色互层的泥岩与粉砂岩相（MFS）、煤（CB）、暗色泥岩相（DM）；8种沉积微相为分流河道相（MS与CS相组合）、河口砂坝相（MS与FS相组合）、天然堤相（FS与MFS相组合）、决口扇相（MS、FS与MFS相组合）、分流间湾相（DM与MFS相组合）、泥炭沼泽相（DM与CB相组合）、远砂坝相（MFS）和海湾或滨浅海相（DM）。在此基础上，采用层序地层方法进行等时地层对比，发现本区三角洲沉积序列含有4个沉积旋回，C1旋回早期以前三角洲的海湾相为主，晚期为三角洲前缘和三角洲平原沉积；C2旋回早期以三角洲前缘、前三角洲和三角洲平原沉积为主，晚期为三角洲平原沉积；C3旋回早期为三角洲前缘沉积，晚期为三角洲平原沉积；C4旋回主要以三角洲平原为主和陆相的河流沉积。

Permian Paralic Basin Sedimentary Paleogeographic Evolution of Gently DiDDin~ Delta in Southwestern Shandong

Using sedimentological and petrological methods combined with field outcrop measuring and borehole observation, 6 lithofa- cies and 8 sedimentary microfacies have been identified. In which, 6 lithofacies have grayish yellow coarse sandstone （CS）, light gray me- dium sandstone （MS）, light gray fine sandstone （FS）, dark gray intercalated mudstone and siltstone （MFS）, coal （CB） and dark mudstone （DM）; 8 sedimentary microfacies have distributary channel （associated MS and CS）, channel-mouth bar （associated MS and FS）, levee （associated FS and MFS）, crevasse splay （associated MS, FS and MFS）, interdistributory bay （associated DM and MFS）, peat bog （associ- ated DM and CB）, distal bar （MFS）, and bay or littoral-neritic （DM）. On this basis, carried out isochronous strata correlation through se- quence stratigraphic method, found that the delta sedimentary succession in the area contains 4 cycles, the cycle C1 is mainly bay facies of predeha in early stage, delta front and delta plain in later stage; cycle C2 is mainly delta front, predelta and delta plain in early stage, delta plain in later stage; cycle C3 is mainly delta front in early stage, delta plain in later stage; cycle C4 is mainly delta plain and conti- nental fluvial deposits.