摘要
榆302孔位于松辽盆地东部边缘,钻深899.30 m, 顶部3.15 m为第四系,上部683,65 m以砂岩为主,夹少量泥岩,下部212.50 m以灰色泥岩为主,夹砂岩及少量凝灰岩。以盆地内岩石地层比较,其上部应属登楼库组3段,下部为登楼库组2段,剖面缺失登楼库组4段,未钻及登楼库组1 段。整个剖面上的孢粉组合面貌基本一致,共有苔藓、蕨类植物孢子40属70余种、裸子植物花粉19属28种、被子植物花粉2属3种、藻类及疑源类6属8种。组合中的绝大部分属种都是我国北方早白垩世孢粉植物群的常见分子,如Cicatricosisporites(约占组合的7%—35%),Appendicisporites, Impardecispora, Pilosisporites, Aequitriradites, Kuylisporites, Triporoletes等。特别有意义的是自登楼库组2段开始即已出现大孢子Balmeisporites holodictyus,被子植物花粉Polyporites debi lis, Retitricolpites sp. 和沟鞭藻Vesperopsis zhaodongensis。登楼库组3 段出现曾见于阿尔布期的Scopusporislautus 及晚白垩世的Scopusporis verrucosus, Trochicola scollardiana, Verrucosisporites fuyuensis 等,证明其时代属早—中阿尔布期。榆302孔的孢粉证据表明登楼库组至少自登楼库组2 段起已进入阿尔布期,至于登楼库组1段因无更多新的资料佐证,阿普特期的时代定位?
The Denlouku Formation, lying unconformably on Barremian-Aptian Yincheng Formation and overlain disconformably by Cenomanian (?)-Turonian Quantou Formation, is a series of terrestrial clastic sediments developed in Songliao Basin (Text-fig.1) and has been divided lithologically into four members named by number ascendingly. Li and Liu (1994) referred the formation to Albian age based on the palynological evidence from the borehole Yu-302 drilling in Yushu at eastern margin of the basin, while Gao et al. (1999) and Zhao (2000) considered the age of the formation to be Aptian (Members 1—3) to Albian (Member 4) on the palynological data from the center of the basin. The present restudy demonstrated that the strata revealed by borehole Yu-302 includes only the Members 2 and 3 of the Denglouku Formation (Text-fig.2) based on lithological correlation within the basin and yield similar palynological assemblages through the whole sequence. The assemblage is composed of 108 species assigning to 67 genus of bryophyte and pteridophyte spores and gymnospermous and angiospermous pollen and other palynomorphs (Tab.1) and dominated by Cicatricosisporites spores (7%—35%). Most taxa of the assemblage are those common seen in the Early Cretaceous assemblages of North China (Li and Liu, 1994), such as the species of Cicatricosisporites, Appendicisporites, Impardecispora, Pilosisporites, Aequitriradites, Kuylisporites and Triporoletes. However, the appearance of the angiospermous pollen Polyporites debilis Hua and Retitricolpite spp. and the spores Balmeisporites holodictyus Cookson et Dettmann, Scopusporis lautus Wingate, Scopusporis verrucosus (Chlonova) com. nov., Trochicola scollardiana Srivastava and Verrucosisporites fuyuensis sp. nov., which were known from Albian or later sediments, and the lack of tricolporate angiospermous pollen may confirm an Early to Middle Albian age to the assemblage. The palynological evidence from the Yu-302 indicates that at least the Members 2 to 4 of the Denglouku Formation in the Songliao
出处
《古生物学报》
CAS
CSCD
北大核心
2005年第2期209-228,共20页
Acta Palaeontologica Sinica
基金
国家重点基础研究发展规划项目(G2000077700)资助
