宁夏中卫晚石炭世维斯发期孢粉组合

WESTPHALIAN SPOWESTPHALIAN SPORO-POLLEN ASSEMBLAGESFROM THE UPPER CARBONIFEROUSIN ZHONGWEI, NINGXIA

研究了宁夏中卫下河沿上石炭统羊虎沟组孢子花粉化石５５ 属９８ 种，建立了两个孢粉组合带，即Ｌａｅｖｉｇａｔｏｓｐｏｒｉｔｅｓ ｍ ｅｄｉｕｓ－Ｃｙｃｌｏｇｒａｎｉｓｐｏｒｉｔｅｓ ａｕｒｅｕｓ （ＭＡ）带和Ｔｏｒｉｓｐｏｒａ ｓｅｃｕｒｉｓ－Ｐｕｎｃ－ｔａｔｉｓｐｏｒｉｔｅｓｈｉａｎｓ（ＳＨ）带，其地质时代分别相当于维斯发Ａ－Ｂ期和维斯发Ｃ－Ｄ期．根据孢粉植物群特征，结合古地磁证据。

About 98 speciesoffossilspores and pollen referred to 55 genera from the Upper Car- boniferous Yanghugou Form ation in Zhongw ei, Ningxia have been studied. Tw o sporo- pollen assem blage zones are recognized in ascending order as follow s∶1. Laevigatosporites m edius-Cyclogranisporites aureus (MA) zone∶This assem blage corresponds to the low er partofthe Yanghugou Form ation, and ischaracterized by the predom inance ofpteridophy- tic sporesand therelative abundance ofgym nosperm ouspollen. Azonotriletesand m onoletes are dom inant, w hile zonates are of im portance. The m ost com m on species are Leiotriletes spp., Cyclogranisporites aureus Potoniéet Krem p, Granulatisporites granulatus Ibrahim , MicroreticulatisporitesconcavusButterw orth etWilliam s, M. nobilis(Welcher) Knox, Triq-uitrites bransoniiWilson etHoffm eister, Dictyotriletes bireticulatus (Ibrahim ) Sm ith et But- terw orth, Ahrensisporitesguerickei(Horst) PotoniéetKrem p, Lycospora spp., Crassispora kosankei(Potoniéet Krem p) Bharadw aj, Cirratriradites saturni(Ibrahim ) Schopf, Wilson et Bentall, Laevigatosporites spp., Colum inisporites ovalis Peppers, Florinites junior Potnié etKrem p and Vesicaspora w ilsonii(Schem el) Wilson et Venkatachata. This assem blage is com parable w ith thoseofthe Yanghugou Form ation in BaiyantaohaiofInnerMongolia (Yu, 1983), the 8th zone of North China by Gao (1979), the Triquitrites sinani-Cirratriradites saturni(SS) Zone and the Microreticulatisporitesnobilis-Florinitesjunior (NJ) Zone ofWest Europe, w hich are considered corresponding to Westphatian A-Bin age. 2. Torispora se- curis-Punctatisporites hians (SH) zone∶This assem blage is equivalent to the upper part of the Yanghugou Form ation, and is also characterized by dom inance of pteridophytic spores and subdom inance of gym osperm ous pollen. In addition to the m ost com m en species m en- tioned above, the im portant taxas in the presentassem blage com prise Punctatisporites hians Wang, Gulisporites cochlearius Im grund, Verrucosisporites kaipingiensis Im grund, En- dosporitesglobiform is(Ibrahim ) Schopf, Wilson et Bentall, Densosporitesanulatus (Loose) Sm ith et Butterw orth, D. reticuloides Ouyang et Li, Sim ozonotriletes labellatus Wang, Torispora securis Balm e, Thym ospora thiessenii (Kosanke) Wilson et Venkatachala, Pityosporites w estphalensisWilliam s and Platysaccus. Illinites. Cycadopites, etc. This zone com pares closely w ith those ofthe upper partof the Yanghugou Form ation in Hengshanbu (Wang Hui, 1984) and OrdosBasin (Geng, 1985), the BenxiForm ation in Shanxi(Liao, 1987; Ouyang and Li, 1980; Gao, 1979), as w elllas Torispora securis-T. laevigata (SL) Zone and Thym ospora obscura-T. thiessenii(OT) Zone ofWestEurope. Therefore, the pre- sentSH Zone should be referred to Westphalian C-Din age. TheWestphalian palynoflora in Zhongw eiis dom inated by Filicopsida and pteridosperm opsida; Sphenopsida and lycopsida occupy the subdom inant position, w hile Cordaitopsida and Coniferopsida do not develop w ell. Thispalynoflora indicates a tropical-subtropicalw arm and hum id paleoclim ate.