塔里木盆地北部地区早—中白垩世地层(白垩系一般为二分,国内外有人主张三分,国内三分条件尚未成熟.本文只是为与国外同行对比行文方便而使用早—中白垩世.)发育,是研究塔里木盆地该断代陆相地层的理想地区之一.亚格列木组过去由于化石较少,时代划分存有争议.笔者等在拜城县卡普沙良剖面首次发现该组孢粉化石之后,本次又发现51属22种(其余为未定种),将该组置于早白垩世贝利阿斯期至凡兰吟期.舒善河组孢粉以往报道很多,化石丰富,根据孢粉本文将该组划为早白垩世欧特里夫至巴列姆期.本次重要发现是该组下部赋存丰富的双手粉(Dicheiropollis),含量可达30％以上,1996年笔者等在该组上部发现含量高达53.7％ ～ 60.5％的双手粉.国内外孢粉学家将其视为早—中白垩世北冈瓦纳孢粉植物区系的典型分子,它出现的时限很短,仅限于早白垩世早—中期.这类花粉如此高含量在本区出现,为重新认识早—中白垩世的植物古地理分区提供了不可多得的证据和材料.许多孢粉工作者都将我国早白垩世孢粉植物区归入南劳亚孢粉植物大区.本次新材料的发现并综合前人资料可以认为早—中白垩世时期新疆塔北地区应归为北冈瓦纳植物区,而且很可能是这类孢粉发展中心地区之一.%The northern part of the Tarim Basin is typical for its terrestrial Lower and Middle Cretaceous sequences. Two formations, namely the Yageliemu Formation and the Shushanhe Formation in ascending order, are found to yield rich spore-pollen assemblages in the Kapushaliang section, Beicheng County, Xinjiang. The age of the Yageliemu Formation has been long time disputed due to the poor discovery of fossils. According to the pollen and spores discovered in this study, the age of this formation fits from the Berriasian to the Valanginian. The Early-Middle Cretaceous floral assemblages in this region contain typical North Gondwanan province elements such as Dicheiropollis etruscus, D. Laevigatus and D. Reticulates; the genus amounts from 30% to 60. 5% of the total. This indicates that the northern Tarim Basin would be one of the most flourishing or dispersal centres of these sporomorphs. Their presence not only provides new data for the age of the Shushanhe Formation but also devote to the reconstruction of Early-Middle Cretaceous floral province and palaeogeography in that region.
展开▼
