准噶尔盆地石莫1井中生代孢粉组合及其地层意义

Mesozoic Sporopollen Assemblages and Their Stratigraphical Significance in Well Shimo-1 of Junggar Basin

为解决准噶尔盆地石莫地区井下地层划分以及与周边地区地层对比问题,对石莫1井中生界孢粉化石进行了系统研究。所见孢粉化石共计98属195种,建立了5个孢粉组合,依次为Concavissimisporites-ClassopollisRugubivesiculites组合,对应下白垩统清水河组;Cyathidites-Cerebropollenites-Piceaepollenites组合,对应下—中侏罗统三工河组;Osmundacidites-Cycadopites-Protoconiferus组合,对应下侏罗统八道湾组;Dictyophyllidites-AratrisporitesAlisporites组合,对应上三叠统白碱滩组至下侏罗统八道湾组下部;Punctatisporites-Converrucosisporites xinjiangensisParataeniaesporites pseudostriatus组合,对应中—上三叠统克拉玛依组。其组合特征可分别与准噶尔盆地南缘清水河组、三工河组、八道湾组、黄山街组和郝家沟组、克拉玛依组孢粉组合对比。孢粉化石资料表明,该井区侏罗系发育不全,缺失头屯河组、齐古组和喀拉扎组;三工河组的时代为早侏罗世晚期—中侏罗世早期,中侏罗统与下侏罗统的界线应划在三工河组下段与上段之间;八道湾组底部时代为晚三叠世,三叠系与侏罗系的界线应划在八道湾组下部。

To solve the problems existed in stratigraphic classification and correlation in Shimo area,the paper systematically studies the Mesozoic sporopollen fossils in Well Shimo-1.The sporopollen fossils can be divided into 195 species of 98 genera,and 5 sporopollen as-semblages are identified,including the Concavissimisporites-Classopollis-Rugubivesiculites assemblage corresponding to the Lower Creta-ceous Qingshuihe formation,Cyathidites-Cerebropollenites-Piceaepollenites assemblage corresponding to the Lower-Middle Jurassic San-gonghe formation,Osmundacidites-Cycadopites-Protoconiferus assemblage corresponding to the Lower Jurassic Badaowan formation,Dicty-ophyllidites-Aratrisporites-Alisporites assemblage corresponding to the Upper Triassic Baijiantan formation-the Lower Jurassic Badaowan formation,and Punctatisporites-Converrucosisporites xinjiangensis-Parataeniaesporites pseudostriatus assemblage corresponding to the Mid-dle-Upper Triassic Karamay formation.The characteristics of the 5 sporopollen assemblages can be correlated with the assemblages in the Qingshuihe formation,Sangonghe formation,Badaowan formation,Huangshanjie formation and Haojiagou formation,and Karamay forma-tion in the southern margin of Junggar basin,respectively.The data of the sporopollen fossils show that the strata of Jurassic are incomplete-ly developed in the wellblock with the absences of Toutunhe formation,Qigu formation and Kalazha formation;the age of Sangonghe forma-tion may be the late of Early Jurassic-the early of Middle Jurassic,the stratigraphic boundary between Middle Jurassic and Lower Jurassic should be located between the upper and lower member of Sangonghe formation;the age of the bottom of Badaowan formation may be the late Triassic,and the stratigraphic boundary between Triassic and Jurassic should be the lower Badaowan formation.