渤海湾盆地中生代地层划分与对比

Stratigraphic Subdivision and Correlation of the Mesozoic in the Bohai Bay Basin

渤海湾盆地中生界长期缺乏统一的岩石地层格架.基于测井、录井、孢粉组合及年龄数据分析,开展了地层划分和对比研究.研究表明,中生界可划分为8个岩石地层单元:(1)三叠系陆相红层,发育Aratrisporites-Triassisporis-Chordasporites组合,最大沉积年龄为(241.4±6.8)Ma至(248.2±1.9)Ma;(2)侏罗系含煤地层,发育Cyathidites-Osmundacidites-Cycadopites-Classopollis组合,最大沉积年龄为(173.4±1.1)Ma至(187.2±4.8)Ma;(3)侏罗系灰色砂岩层,发育Cyathidites-Osmundacidites-Deltoidospora-Cycadopites组合,最大沉积年龄为(155.3±1.3)Ma至(164.4±3.8)Ma;(4)侏罗系红色砂砾岩层,发育Classopollis-Abietineaepollenites组合;(5)下白垩统下部含基性火山岩红层,发育Cicatricosisporites-Lygodiumsporites-Classopollis组合;火山岩年龄在140~132 Ma之间;(6)下白垩统中部含中、基性火山岩灰色地层,发育Lygodiumsporites-Cicatricosisporites-Osmundacidites-Cycadopites组合,火山岩年龄在130~116 Ma之间;(7)下白垩统上部含中、基性火山岩地层,发育Cicatricosisporites-Schizaeoisporites-Classopollis-Piceites组合,火山岩年龄在119~103Ma之间;(8)上白垩统含酸性火山岩红层,发育Schizaeoisporites-Ephedripites-Classopollis组合,火山岩年龄在76~69Ma之间.

The Mesozoic in the Bohai Bay basin lacks unified stratigraphic framework.Based on logging data,sporopollen assemblage and age analysis of clastic and volcanic rocks,the stratigraphic subdivision and correlation of the Mesozoic were studied.The Mesozoic strata can be divided into eight stratigraphic units.The Triassic continental red strata develops the AratrisporitesTriassisporisChordasporites assemblage,and the maximum depositional ages range from(241.4±6.8)Ma to(248.2±1.9)Ma.The CyathiditesOsmundaciditesCycadopitesClassopollis assemblage forms in the Jurassic coal-bearing strata,and the maximum depositional ages of the strata are from(173.4±1.1)Ma to(187.2±4.8)Ma.For the Jurassic gray sandstone strata,the maximum depositional ages range from(155.3±1.3)Ma to(164.4±3.8)Ma and the CyathiditesOsmundaciditesDeltoidosporaCycadopites assemblage are developed.The Jurassic red sandstone and gravel strata develop the ClassopollisAbietineaepollenites assemblage.In early stage of early Cretaceous,the red clastic strata with basic volcanic rock and the CicatricosisporitesLygodiumsporitesClassopollis assemblage formed.The volcanic rocks ages are from 140 to 132 Ma.For the gray clastic strata with intermediate-basic volcanic rock in the middle part of the lower Cretaceous,the LygodiumsporitesCicatricosisporitesOsmundaciditesCycadopites assemblage and the volcanic rocks of the ages from 130 to 116 Ma are developed.The clastic strata with intermediate-basic volcanic rock in the upper part of the lower Cretaceous develop the assemblage of CicatricosisporitesSchizaeoisporitesclassopollis⁃Piceites,and the volcanic rocks ages range from 119 to 103 Ma.The Schizaeoisporites⁃Ephedripites⁃Classopollis assemblage forms in the Upper Cretaceous red clastic strata with acidic volcanic rock ranging from 76 to 69 Ma in age.