白音查干凹陷古生态及古气候探讨

Discussion on palaeoecology and palaeoclimate of Baiyinchagan Depression

从介形类化石群的成分、产状与丰度、个体形态特征及孢粉组合特征等多方面对白音查干凹陷的古生态及古气候进行了探讨,认为阿尔善组沉积期为白音查干凹陷中生代断陷湖盆发育初期,湖盆地形高差大,物源丰富,生物不发育,气候为较干燥的热带—亚热带型;腾格尔组沉积期,湖盆面积扩大,水体加深,生物活动加强,气候为干旱的热带—亚热带型;都红木组沉积期,湖盆范围进一步扩大,水深进一步增加,水体盐度适于生物生长,生物种类繁多,数量丰富,气候逐步转为湿润的热带—亚热带型,其中都二段沉积期为该凹陷湖盆发育的最鼎盛时期;赛汉塔拉组时期,盆地回返,湖盆逐渐消亡,生物不发育,气候转为干燥的热带—亚热带型。

This paper discusses on the palaeoecology and palaeoclimate of Baiyinchagan Depression from the composition, occurrence, abundance, individual morphological features of ostracode fossils and sporopollen assemblage features. It is thought that the deposition of Aersan Formation is initial development of Mesozoic faulted lake basin with big elevation difference, rich source and undeveloped organism in Baiyinchagan Depression. The climate of this period is dry tropical to subtropical zone. When Tenggeer Formation deposits, the lake basin spreads, water body becomes deeper and bioactivity becomes strong. The climate is also dry tropical to subtropical zone. When Duhongmu Formation deposits, the lake basin spreads more widely, water becomes deeper and deeper, salinity is suitable for many varieties of organisms to grow. The climate turns to be wet tropical to subtropical zone. The deposition of Du 2 Member is the top development of this faulted lake basin. When Saihantala Formation deposits, the basin becomes to disappear with no organism development. The climate turns to be dry tropical to subtropical zone again.