副蝴蝶虫(Parablackwelderia)在山东的发现及其地层学意义

THE FIRST RECORD OF Parablackwelderia FROM LAIWU AND XINTAI,SHANDONG AND ITS STRATIGRAPHIC SIGNIFICANCE

在山东莱芜-新泰地区盘车沟剖面崮山组底界上下首次发现了副蝴蝶虫(Parablackwelderia)。研究表明Parablackwelderia是独立的属,而非Blackwelderia的晚出异名。长期以来,作为我国华北寒武纪崮山组和崮山阶(期)的标准地区,山东的崮山组被认为与崮山阶完全相当,这个认识在莱芜-新泰地区需要修正,新的化石材料表明,该区的崮山组下部有一部分为张夏期的沉积。也就是说,在该区崮山组的底界与崮山阶的底界并不一致,崮山阶的底界要高于该组的底界,位于崮山组内。因此,在莱芜-新泰地区崮山组是一跨阶(期)的岩石地层单位。莱芜-新泰地区可能比作为标准的长清张夏地区更早地接受崮山组的沉积。同时澄清了长期争议的崮山组上下界线附近动物群混生的错误认识,可能是把Parablackwelderia鉴定为Blackwelderia。

Parablackwelderia Kobayashi,1942 is recorded for the first time from the lower part of the Gushan Formation at the Jiulongshan and Panchegou Sections,western Shandong.We concluded that Parablackwelderia is a valid genus,not a junior Synonym of Blackwelderia.For a long time,as the type area of the Cambrian System of North China,the Gushan Formation of Shandong has been equated to the Gushanian Stage,but this is incorrect at least in the Laiwu-Xintai area.New fossils indicate that the lower part of the Gushan Formation in this area belongs to the Changhsian Stage.Thus,the lower limit of the Gushan Formation and lower limit of the Gunshanian stage are not the same in the Laiwu-Xintai area,and the lower limit of the Gushanian Stage lies within the Gushan Formation.Consequently,as a litho-stratigraphy unit,the Gushan Formation in the Laiwu-Xintai area is diachronous.And the initial deposition of the lower Gushan Formation in the Laiwu-Xintai area was earlier than in the Changqing-Changhia area.We also clarified the confusion about the mixed fauna near the lower boundary of the Gushan Formation,which was in part caused by the misidentification of Parablackwelderia as Blackwelderia.