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 Aratrisporites-Triassisporis-Chordasporites assemblage,and the maximum depositional ages range from(241.4±6.8)Ma to(248.2±1.9)Ma.The Cyathidites-Osmundacidites-Cycadopites-Classopollis 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 Cyathidites-Osmundacidites-Deltoidospora-Cycadopites assemblage are developed.The Jurassic red sandstone and gravel strata develop the Classopollis-Abietineaepollenites assemblage.In early stage of early Cretaceous,the red clastic strata with basic volcanic rock and the Cicatricosisporites-Lygodiumsporites-Classopollis 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 Lygodiumsporites-Cicatricosisporites-Osmundacidites-Cycadopites 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 Cicatricosisporites-Schizaeoisporites-classopollis-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.
stratigraphic subdivisionstratigraphic correlationsporopollen assemblagemaximum depositional agesMesozoicBohai Bay basinstratigraphygeochronology
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