塔里木盆地北部晚泥盆世孢子组合

UPPER DEVONIAN SPORES FROM THE NORTH TARIM BASIN, NW CHINA

塔里木盆地北部草 2井东河塘组产丰富的、保存完好的孢子化石 ,计 37属 73种 ,据此建立Apiculire tusisporahunanensis Ancyrosporafurcula (HF)孢子组合带。对一些孢子的已知地质分布记录及其与西欧和塔西南晚泥盆世孢子组合带序列的对比讨论 ,表明HF孢子带的时代为晚泥盆世法门期 ,大致与爱尔兰晚泥盆世LL +LE孢子带时代相当。描述孢子 3新种 ,图示孢子

The present paper concerns chiefly with the Donghetang Formation of borehole Cao 2, North Tarim Basin, with emphasis laid on the description and the age of the proposed spore zone from a palynological point of view. Seventy three miospore taxa assigned to thirty seven genera have been recognized, of which, 61 species of spores are illustrated in the plates, three species are discribed as new. Based on the quantitative and qualitative analyses of compositions of spore assemblages, a new spore zone, i.e. Apiculiretusispora hunanensis Ancyrospora furcula (HF) zone is proposed to accomodate the miospores found from the Donghetang Formation. The HF spore assemblage zone is dominated by three spore taxa (each over 10%): Apiculiretusispora hunanensis (Hou) Ouyang et Chen, A. rarissima Wen et Lu and Spelaeotriletes radiatus Zhu. Some species are frequent (3%—10%) in the zone: Aneurospora tarimensis Zhu, Apiculiretusispora fructicosa Higgs, Auroraspora conia Zhu, A. corporiga Higgs, Clayton et Keegan, Spelaeotriletes spissus sp. nov., Cymbosporites bellus Zhu, C. tarimensis Zhu, Grandispora clandestina Playford, Punctatisporites debilis Hacquebard and Retusotriletes planus Dolby et Neves. The following spores are common (1%—3%): Ancyrospora langii (Taugourdeau Lantz) Allen, Apiculiretusispora nitida Owens, Auroraspora macra Sullivan, Geminospora spongiata Higgs, Clayton et Keegan, Grandispora uniformis Zhu, Punctatisporites planus Hacquebard, Raistrickia platyraphia Zhu, Retusotriletes incohatus Sullivan, Rugospora sp., Tumulispora ordinaria Staplin et Jansonius, etc. Comparison of the Late Devonian to Early Carboniferous miospore assemblages of western Europe with that of North Tarim Basin suggests that the HF zone of borehole Cao 2 can be roughly correlated with the LL and LE zones of the Irish palynological zonation and the age of zone HF is Late Devonian. Although none of the spores are assignable to Retispra lepidophyta (Kedo) Playford in the HF zone, the fact that twenty seventy common spore species, including Retispora cassicula (Higgs) Higgs et Russell, Ancyrospora furcula Owens, A. involucra Owens, Diducites versabilis (Kedo) Van Veen, Knoxisporites literatus (Waltz) Playford, Apiculiretusispora hunanensis (Hou) Ouyang et Chen, and Grandispora gracilis (Kedo) Streel, etc. recognised from both the present HF zone and the RL zone of the Qizilafu Formation of Sache County, SW Tarim Basin, the latter is believed to be a correlative of the Donghetang Formation and Late Devonian in age according to fossil plants Leptophloeum rhombicum Dawson, brachiopod Cyrtospirifer spp. and spores Retispora lepidophyta (Kedo) Playford in association with them, lends support to the present age determination. Besides, the Antiarchian fish fossils from the same horizons with the HF spore assemblage in borehole Cao 2 (Wang, 1997) also indicates an age of Devonian.