内蒙古二叠系哲斯组的牙形刺及其时代

CONODONTS FROM THE PERMIAN JISU HONGUER(ZHESI) FORMATION IN INNER MONGOLIA, CHINA

哲斯组是我国北方最有代表性的海相二叠纪地层,但其时代尚未得到解决。以往的研究多偏重于底栖大化石,难以解决洲际间的对比。作者对哲斯组的牙形刺进行了研究,在哲斯组上段下部发现了Mesogondolellaaserrata动物群,从其同层的其它牙形刺化石分析,产这一牙形刺化石的层位的时代应为Wordian期晚期至Capitanian期早期,而整个哲斯组的时代可能为中二叠世Wordian期至Capitanian期早期,推测义和乌苏组的时代可能为Capitanian期。哲斯地区可能不存在吴家坪阶的海相沉积。对MesogondolellaneoprolongataWang,2004,M.mandulaensisWang,2004,WardlawellajisuensisWang,2004作了重新描述,这3个种可能为地方性分子或北方区(Borealrealm)分子。

The Jisu Honguer Formation （the Zhesi Formation） is the most typical Permian marine deposits in North China, but its age had not been determined in the last century, the previous study was focused on benthic macrofossils which can not be used for precise international correlation. The present paper provides a conodont study. A typical Mesogondolella aserrata Fauna has been found in the lower part of the upper member of the Jisu Honguer （Zhesi） Formation, indicating that the age of the Jisu Honguer （Zhesi） Formation should be Middle Permian Wordian Stage, most probably Wordian to early Capitanian. The Yihewusu Formation should be assigned to the Capitanian. There are no Wuchiapigian marine deposits in Zhesi area. As characteristic for the open sea Guadalupian conodont faunas of the Tethys, smooth Mesogondolella are dominating （Kozur, 1995; Kozur et al. , 2001）. Three species are redescribed in Chinese in this paper： Mesogondolella neoprolongata C-y Wang, Mesogondolella mandulaensis C-y Wang, and Wardlazoella jisuensis C-y Wang. Original description is published in Geobios 37（2004）, 471--480.