从孢粉组合论证松辽盆地泉头组的地质时代及上、下白垩统界线

松辽盆地发育我国最好的白垩纪地层,岩石地层系统早已确立,但年代地层系统仍存不少争议。泉头组时代的确定是解决盆地内上,下白垩统界线的关键。泉头组上部孢粉化石丰富,孢粉组合以频繁出现Quanto nenpollenites crassatus,及Schizaeoisporites,Asterisporites,Foraminisporis,Cibotiidites等属孢子,Quantonenpollenites tarimensis及被子植物花粉Cranwellia,Scollardia,Lythraties,Xinjiangpollis等少量出现为主要特征,与塔里木盆地库克拜组上段的孢粉组合可以比较,时代应为土仑期,泉头组为一套连续沉积,与其下的登楼库组（阿尔必期）为平行不整合关系,泉头组下部的孢粉组合中被子植物花粉的分异度尚低,但已有相当含量（最高达30．3％）,可与塔里木盆地库克拜组中,下段的孢粉组合比较,时代为赛诺曼期,孢粉化石的研究表明,松辽盆地上,下白垩统的界线应在泉头组的底界,即泉头组与登楼库组之间,而不是在泉头组的顶界,文内描述1新种：Interulobites radialimbosus sp.nov.,5新组合：Neoraistrickia rareuverrucosa(Chlonova)comb.nov.,Asterisporites montanensis(Tschudy)comb.nov.,Cranwellia striatella(Mtschedllishvili)comb.nov.,Quantonenpollenites causea(Stover)comb.nov.,Quantonenpollenistes tarimensis(Zhoang et Zhan)comb.nov,并修订了Yichangsporites和Quantonpollenites属的特征。

PALYNOFLORA FROM THE QUANTOU FORMATION OF SONGLIAO BASIN, NE CHINA AND ITS BEARING ON THE UPPER-LOWER CRETACEOUS BOUNDARY

In the Songliao Basin of northeastern China is well developed a non marine Cretaceous sequence composed of 10 lithological formations (see Li Wen ben and Liu Zhao sheng, 1994, fig.16). Although all the formations are rich in fossils including bivalves, gastropods, conchostracans, ostracods, fishes, reptiles, charophytes, sporomorphs and plant megafossils, researchers on different fossil groups have not yet reached a consensus to chronological problems for each formation. Unfortunately, the divergence of view points even exists among the palynologists. For the Upper Lower Cretaceous boundary, palynologists have given two different proposals: between the Quantou and Denglouku formations (Li Wen ben and Liu Zhao sheng 1994) and between the Qinshankou and Quantou formations (Gao Rui qi, 1982; Gao Rui qi et al ., 1999). Obviously, the dispute is mainly caused by the different datings of the Quantou Formation.