西藏申扎永珠乡晚石炭世和早二叠世的腕足动物化石

UPPER CARBONIFEROUS AND LOWER PERMIAN BRACHIOPODS FROM SHENZHA COUNTY, XIZANG (TIBET)

申扎地区石炭二叠系发育良好,化石丰富。本文描述的化石采自上下两个层位,下部化石少,以石燕贝类为主, 其组合特征反映了石炭纪腕足类的特点与改则县玛米雪山地区上石炭统所产相似;上部化石丰富,以石燕贝类的Spiriferella和Syrin-gothyris的出现为特征,共生还有长身贝类的Chonetinella,Echinauris,Tylo-pecta等。这个化石组合与西藏其他地区相同时代的化石组合不同。特别是Syringothy-ris在下二叠统的发现具有重要意义。

Fossils described in this paper were collected in 1979 by Wang mingzhou, Cheng Liren and others of Xizang Research team of Changchun University of Earth Sciences from Yongzhu Village of Shenzha County. Fossils were collected from two horizons including 11 genera and 14 species as following: Schel-lwienella sp., Chonetinella sp. ,Echinauris circularis Cooper et Grant,,Marginifera sp.,Tylopecta sp.,Syringothyris sp. 1, Syringothyris sp. 2, Spirifer sp.,Neospi-rifer spp.,Spiriferella cf. qubuensis Chang,S. cf. sinica Chang,Stenoscisma cf. multicostum Stehli, Stenoscisma sp.,and Hustedia sp. The Lower horizon is characterized by Spirifer, Neospirifer and Schellwienella etc.,bivalve Deltopecten was also found in this horizon, whichclosely resemble to those in Mamixueshan Formation of upper Carboniferous in Gai Ze County. The upper horizon yields abundant fossils including Chonetinella, Echinauris, Tylopecta, Syringothyrts, Spiriferella Stenoscisma and Hustedia. The discovery of Syringothyris in upper horizon together with Spiriferella cf .qubuensis Chang and S. cf. sinica Chang, Stenoscisma cf. multicostum Stehli etc. is very significant because Syringothyris is usually found in Lower Carboniferous in Xizang.Fan Yingnian (1988) reported Syringothyris occurred in the upper Carboniferous in Shen Zha, but no exact information of Syringothyris was reported in Permian of Xizang.The brachiopod assemblage of theupper horizon closely resembles to that of Houtoumiao Formation of Xiujimqinqi in Inner Mongolia. Syringothyris sp. 1 and S. sp. 2 closely resembles to Syringothyris sp. B and Syringothyris sp. A of Xiujimqinqi respectively; Spiriferella qubuensis Chang and S.sinica Chang were first described by Chang and Ching (1976) from Selong Formation of Permian in Himalayan Region and was reported by Zhan et al (1982) from Permian of Shen Zha. Stenoscisma multicostum Stehli has been reported from Hess, Cibolo, and Bone Spring Formation of Sakmarian-Artinskian age in Texas. Therefore, the upper horizon is Permian in age; according to lithological characters it is referred to Ri-a Formation.