辽西热河群上亚群孢粉组合

辽西热河群含有丰富的煤炭资源,它的时代归属问题,是我国中生代地层长期争论的焦点。作者从热河群上亚群三个岩组发现了丰富而保存完好的孢子花粉。本文建立了上亚群三个孢粉组合序列,从老至新为:九佛堂组是以Concavissimisporites-Heliosporites-Aeq-uitriradites为代表的组合,时代为早白垩世早期;沙海组是以Cicatricosisporites-Pilosisporites-Piceaepollenites为代表的组合,时代为早白垩世中期;阜新组以Appenidicisp

SPORO-POLLEN ASSEMBLAGES FROM THE UPPER PART OF THE REHE GROUP, LI AONING PROVINCE

The Rehe Group is widely distributed in the Western Liaolin Province. The upper part of this Group is represented by grey, yellowish green, black coloured conglomerate, sandstone, siltstone, siltpelite, battie and oil shale with thick coal-seams. It can be subdivided (in ascending order) into Jiufotang Formation, Shahai Formation and Fuxin Formation and three palynological assemblages may be recognized as follows:1) Concavissimisporiies-Heliosporites-Aequitriradites assemblage (Jiufotang Formation). It contains plenty of Concavissimisporites(l.6-6.8%), Densoisporites (2.0-7.9%), Aequitriradites(1.2-8.8%)and Osmundacidites (2.0-9.2%), species of those above genera: Concavissimisporites variverrucatus, C. punctatus, C. longiverrucatus, C. potoniei, C. penolaensis, Densoisporites microrugulatus,Aequi-triradites tilchaensis, A. verrucosus and A. ornatus etc. Cicatricosisporites, Impar-decispora, Foraminisporis and Heliosporites occur frequently, While these genera count less than 3.0%, together with scacity of Couperisporites complexus, Pilosisporites verus, Fixisporites tortus and Polycingulatisporites reduncus, suggesting the early Early Cretaceous (Valanginian) in age.2) Cicatricosisporites - Pilosisporites - Piceaepollenites assemblage (Shahai Formation). The assemblage appears to be distinguished from that of the under assemblage by the relative abundance of Cicatricosisporites (6.7%), comprising C. hldbrooki, C. subrotundlts, and C.pacificus. The proportion of Pilo- sisporites amounnts to 3% of the total number besides P. verus, here occuring P. trichopapillosus. It is the first time that there appears Appendcisporites which is accompained by a large number of Cyathidites, Deltoidospora and Laveigatosporites. Aequitriradites and Densoisporites which are relatively abundant in the Jinfotang Formation and become very rare in this assemblage. This assemblage is dominated by winged Conifer us pollen, with long-ranging elements, such as Callialu sporites, Cerebropollenites, Araucariacites, Cycadopites andPerinopollenites, referring to Early Cretaceous (Hauterivian-Barxemian) and it may be compared with the Wealden assemblage in southern England.3) Appendicisporites-Cicatricosisporites-Clavatipollenites assemblage (Fuxin Formation). Cicatricosisporites increases teadily and reaches 21.0% of the total number in the upper part of the Formation. The Appendices parites becomes abundant(7.6)and includes A.crimensis, A.auritus, A. potomacensis, A. erdtmanii, A. bilateralis, and A. perforatus. And it is rich in Laevigatosporites (16-50.0%) and Deltoidospora with a few Crybelosporites striatns, C. speciosus, Knylisporites lunaris, Triporoletes reticulatus and Foraminisporis wontha ggiensis.It should be noted that Clavatipollenites and Tricolpites make their first appearance only in this Formation. It belongs to late Early Cretaceous(Aptian -early Albian).