松辽盆地来D13井地层划分对比研究

岩石组合特征和同位素数据表明,松辽盆地来D13井137.0—142.0m井段属于早白垩世晚期(Aptian—Albian期)营城组。104.2—137.0m井段光山核桃粉(Caryapollenites simplex)-拟榛莫米粉(Momipites coryloides)-朴粉未定种(Celtispollenites sp.)-具缘铁杉粉(Tsugaepollenites igniculus)组合特征可以与前人的大安组孢粉组合特征对比,反映的都是暖温带至北亚热带中生气候,而与晚白垩世嫩江组的孢粉组合特征截然不同,应该确定为早中新世晚期至中中新世的大安组。54.2—104.2m井段小蒿粉(Artemisiaepollenites minor)-拟桦粉未定种(Betulaceoipollenites sp.)-枥粉未定种(Carpinipites sp.)-水龙骨单缝孢未定种(Polypodiaceaesporites sp.)组合特征可以与前人的泰康组孢粉组合特征对比,反映的都是暖温带至北亚热带中生偏旱气候,这与前人依据岩石组合特征确定为泰康组的结论一致,孢粉组合时代分析表明,该井段沉积的时间为晚中新世至上新世初期。研究结果丰富了松辽盆地新近纪孢粉地层学内容,为松辽盆地西部斜坡区井下新近纪孢粉地层学对比提供了新资料,也为邻区新近纪生物地层学对比以及古植被和古气候分析提供了新的依据。

STRATIGRAPHIC SUBDIVISION AND CORRELATION OF BOREHOLE LAI D13IN THE SONGLIAO BASIN,NE CHINA

The lithological characteristics and isotopic dating indicate that the layer of the well depth 137.0—142.0m in Borehole Lai D13 belongs to the late Early Cretaceous(Aptian—Albian)Yingcheng Formation,rather than the Huoshiling Formation assigned formerly.The layer of the well depth 104.2—137.0min Lai D13 yields pollen and spores assemblage named Caryapollenites simplex-Momipites coryloides-Celtispollenites sp.-Tsugaepollenites igniculus assemblage.The assemblage can be correlated to that of the Da'an Formation.Both assemblages suggest a mesophytic climate from warm temperate to north subtropical zone.This is totally different from that of the late Cretaceous Nenjiang Formation,although they are similar lithologically.Therefore,this layer should be assigned to the Da'an Formation,being the late Early Miocene to middle Middle Miocene.The layer of well depth 54.2—104.2min Lai D13,yields pollen and spores assemblage Artemisiaepollenites minor-Betulaceoipollenites sp.-Carpinipites sp.-Polypodiaceaesporites sp.This assemblage is comparable with that of the Taikang Formation,and indicates a xerophilous mesophytic climate from warm temperate to north subtropical zone.This layer should be assigned to the Taikang Formation.This is consistent with the previous result based on the lithological correlation.The age of this layer is the Late Miocene to the Early Pliocene,according to the palynological data.The above results enrich the research on Neogene palynological stratigraphy in the Songliao Basin.It provides new data on the correlation of Neogene strata among the boreholes in the west slope of Songliao Basin,and new basis for both biostratigraphical correlation and paleovegetational and paleoclimatical analysis in the adjacent regions.