中国古生代放射虫十年来研究的进展

ON PROGRESS IN THE STUDY OF PALEOZOIC RADIOLARIANS IN CHINA

自1982年以来,我国古生代放射虫研究取得了很大的进展,自奥陶纪至二叠纪放射虫化石相继在许多地点发现,早古生代的放射出在华北和西北地区分布较为广泛,晚古生代的则在华南多见,在北方较少。文章简单介绍了10年来我国古生代放射虫的研究状况.包括已发现的Llanvirnian期、Llandeiloan—Early Caradocian期、Ashgillian期、Wenlockian中期、中泥盆世、Frasnian期、Famennian期、Tournaisian期、Wolfcampian期、Guadalupian期和Changhsingian期放射虫动物群特征及其对比,并提出了今后研究的方向、重点地区和目标层位。

The study of Paleozoic radiolarians in China has been much improved ever since thepublication of the first paper on Paleozoic Radiolaria in 1982(Sheng & Wang, 1982, inChinese) with radiolarian faunas ranging from Ordovician to Permian discovered in manylocalities. This paper gives a summary of the progress in the study of Paleozoic radiolariansduring the last 10 years. All the materials used in this paper have not been published unlessotherwise stated. The Early Paleozoic radiolarians are mainly distributed in North and NorthwestChina. The Llanvirnian radiolarians found in the limestones of the Klimuli Formation inTongxin, Ningxia, are dominated by the family Inaniguttidae, including Haplentactiniaarmillata (Nazarov), Inanigutta akdjmensis (Nazarov), Inanibigutta sp. cf. I. verrucula(Nazarov), Inanihella bakanasensis(Nazarov), Anakrusa sp., etc., in association with the graptolite Amplexograptus confetus Zone. This fauna is similar to the Arenigian--Llanvirnian radiolarians of central Kazakhstan, USSR and may be correlated with theHaplentactinia armillata-Proventocitus procerulum Assemblage Zone (Nazarov, 1988). The Llandeilian-Early Caradocian radiolarians have been found in the limestones ofthe Pingliang Formation in Pingliang and Huanxian, Gansu, as well as in the cherts on thenorth bank of the Ebinur Lake, Xinjiang. The Pingliang Formation contains Inanihellapenrosei (Ruedemann et Wilson), Inanigutta complanata (Nazarov), Oriundoguttacornuta(Hinde), O. miscella miscella (Nazarov), Cessiphlorum sp. cf. C. aperta (Nazarov),Inanibigutta verrucula (Nazarov), Ceratoikiscum sp. 1, Entactiniidae gen. et sp. 1, in associ-ation with the graptolite Nemagraptus gracilis Zone (Syndyograptus Subzone) and theconodont Pygodus anserrinus Zone. These radiolarians are equivalent to those of easternKazakhstan, USSR in aspects of genera and species. Since the Pingliang radiolarian faunais dominated by Inanihella penrosei (occupying half the total number of individuals), it isnamed the I.penrosei Assemblage Zone, which may correspond to the Middle OrdovicianHaplentactinia juncta-Inanigutta unica Zone (Nazarov, 1988). The Ashgillian radiolarians are yielded from the cherts of the Wufeng Formation inSouth China, but their preservation is so poor that it is rather difficult to make an identifi-cation of the species. Among these radiolarians, a large number of individuals are flattened,with only a few of them still retaining some characters of the inaniguttids, which seem to becomposed of the genera Inanigutta and Inanibigutta. The Middle Silurian (Wenlockian) radiolarians encountered in the tuffaceous siltstonein Kelkada area near Toli, Xinjiang (Li, 1991) are characterized by the presence ofpalaeoactinommids, ceratoikiscids, inaniguttids and palaeosceniids, includingPalaeoephippium radices Goodbody, P. pariramosus Goodbody, Palaeoscenidiumflammatum Goodbody, Palaeotripus cancellatus Goodbody, P. nudus Goodbody,Ceratoikiscum leonides Renz, C. cotoplenra Renz, and so on. These fossils are similar tothose from the Cape Phillips Formation of the Canadian Arctic Archipelago. On the whole, the Early Paleozoic radiolarians of North and Northwest China belongto the same paleobiogeographic realm together with those from Kazakhstan, USSR,Spitzbergen, North America and the Canadian Arctic Archipelago. The Late Paleozoic radiolarians discovered are more common in South than in NorthChina, but no radiolarians of the Early Devonian have ever been found in China so far. The Middle Devonian fossil radiolarians found from the limestones of the ChitzechiaoFormation in Xintian of Hunan (Sheng & Wang, 1982) and from the chert belts in Yingdeof northern Guangdong are characterized by the presence of entactinids which can beroughly correlated with those of Osobudani Assemblage Ⅲ from the Hida-Gaien Belt inthe Fukuji area, Central Japan (Furutani, 1986). The Late Devonian (Frasnian) radiolarians are widely distributed in eastern andsoutheastern Guangxi. This fauna recently found in Hexian, Zhongshan, Lipu and Yulin is dominated by entactinids, including Entacti