西伯利亚西部侏罗纪植物微体化石的热变质作用

研究了西伯利亚西部几个地点钻孔侏罗纪岩芯样中的植物微体化石。在有关组合中，Lycopodium sp., Coniopteris spp.和Gleicheniidites sp.的孢子少，Klukiasporites sp.极少；代表性花为有Pinus exilioides,P.disulgaus,sciadopites sp.和Classopollis;微体浮游植物占优势，例如Crassisphaera sp.,Tasmanites sp.,Pterospermopsis eurypteris. P.harti和Cymatiosphaera sp.颇丰富，有时出现Pareodinia sp.和Trichodinium sp.。虽然各个组合中孢子、花粉、微体浮游植物在含量上有变化，但总的组成在西伯利亚西部不同地区尚稳定，此等微化石的颜色或有变化，它们（特别是微体浮游植物）可用来检测沉积有机质受热变质的成熟度级别。

THERMAL ALTERATION OF JURASSIC VOLGA PLANT MICROFOSSILS OF WESTERN SIBERIA

Core samples from the Jurassic deposits of well sections of Chuel'skaya, Salymskaya, Ombinskaya, Priobskaya,Varioganskaya and other areas were studied. It was revealed that spores of Lycopodium sp., Coniopteris spp. and Gleicheniiditessp. are rare in plant microfossils assemblages; those of Klukiasporites sp. are extremely rare. The following representatives ofpollen were recorded: Pinus exilioides Bolch., P. divulgata Bolch., Sciadopitys sp. and Classopollis sp. Among spores, pollengrains, and microphytoplanktons, the latter dominates. Thus, Crassisphaera sp., Tasmanites sp., Pterospermopsis eurypterisCookson et Eisenack, P. harti Sarjeant and Cymatiospaera sp. are abundant; Pareodinia sp. and Trichodinium sp. sometimesoccur. Although the taxa of pollen, spores as well as microphytoplanktons vary quantitatively in the present assemblages,general composition of these assemblages is constant for different areas of Western Siberia. The colour of plant microfossils,indicating the level of thermal maturation of the sedimentary organic matter, can be different. Accordingly, plant microfossils(in particular very abundant in these deposits microphytoplanktons) can be used for testing catagenesis of the organic matter.