吐哈盆地台北凹陷西山窑组（J2）孢粉组合

台北凹陷是吐哈盆地的主要含油气区，而西山窑组煤系地层是该地区的主力烃源岩。对采自葡１井与草南１井西山窑组孢粉化石的，鉴定和统计，共发现孢粉化石31属57例，依据属种含量分布和地史意义，可建立以Cyathiites－Cycadopites－Quadraeculina为代表的孢粉组合，其中裸子植物花粉略占优势，含量为51％，蕨类植物孢子含量为49％。通过对主要孢粉类型和重要属种地史分布的讨论、与邻区及国内外同时代孢粉组合特征的对比，加之本区西山窑组与下伏早侏罗世晚期的三工河组为整合接触关系，认为西山窑组孢粉组合与陕甘宁盆地中部地区的延安组、辽宁西部的海房沟组等地层所产孢粉组合较相似，其地质时代应属中侏罗世早期，大致相当Aalenian－Bajocian期。

SPORO POLLEN ASSEMBLAGE FROM THE MIDDLE JURASSIC XISHANYAO FORMATION OF THE TAIBEI DEPRESSION IN TUHA BASIN

The Taibei Depression is the main oil and gas bearing area of Tuha Basin, and the coal bearing stratum of the Xishanyao Formation is the most important source rock in the area. The sporo-pollen fossils from the well pu-1 and wel1 Caonan-l have been analyzed, identified and counted. The sporo-pollen fossils discovered from the Xishanyao Formation consist of 31 genera and 57 species. The assemblage is named as Cyathidites-Cycadopites-Quadraec-ulina based on their high percentages and stratigraphic significance. It is characterized by the slight dominance of gymnospermous pollen(51％). The pteridophyta spore amounts to 49％. The genera Cyathidites and Osmundacidites of the pteridophyta spores are predominant, their percentages amounting to 20％ and 13％ respectively. Gleicheniidites, Asseretospora and Deltoidospora are common, their percentages being 2-4％. Among gymnospermae pollen, the most abundant genera are Quadraeculina (17.5％ )and Cycadopites(13.3％). Moreover, Podocarpidites, Piceites and Classopollis are of higher percentage (3.5％, 5.5％ and 4.9％ in order). By analysing the geological distribution of main classes and important species and genera, comparing with the known assemblages which are of the same geologic age from the various districts in the world, and considering the conformable relationship of the Xishanyao Formation with the underlying late Early Jurassic Sangonghe Formation, the author thought that the assemblage of the Xishanyap Formation is similar to the ones from the Yanan Formation of Central Shanganning Basin, the Haifanggou Formation of Western Liaoning Province etc. The geologic age might be referred to early Middle Jurassic(Aalenian-Bajocian).