新疆塔里木盆地塔中地区上奥陶统良里塔格组钙化蓝细菌化石

CALCIFIED CYANOBACTERIA FROM THE UPPER ORDOVICIAN LIANGLITAGE FORMATION,CENTRAL TARIM BASIN,XINJIANG

首次描述塔里木盆地塔中地区井下的上奥陶统良里塔格组的钙化蓝细菌化石2纲、2目、5科11属:Girvanella,Subtifloria,Rothpletzella,Hedstroemia,Ortonella,Garwoodia,Di morphosiphonoides,Izhella,Renal-cis,Proaulopora,Phacelophyton,和存疑分子2属:Wetheredella,Nuia。对多数属进行到种一级鉴定。对Gar-woodiaceae中的几个近似属的鉴定标准进行讨论,对Hedstroemia,Ortonella属的定义进行修改,建议废弃Mi-theldeania,Sphaerocodium两个属名,将原来归入绿藻的Di morphosiphonoides归入蓝细菌。

The Cyanophyceae or blue-green algae in recent decades have been transferred to a group of bacteria,the cyanobacteria.This acknowledges that these organisms are more closely related to the other prokaryotices than to eukaryotic algae. Some cyanobacteria are able to precipitate tiny carbonate grains within their mucilaginous sheath,and so can form fossils in sedimentary strata.Here we des-cribe 11 genera of calcified cyanophycede from well cores of the Upper Ordovician Lianglitage Formation in the central Tarim Basin： Girvanella,Rothpletzella,Subtifloria,Hedstroemia,Ortonella,Garwoodia,Dimorphosiphonoides,Izhella,Renalcis,Proaulopora and Phacelophyton.Accor-ding to Luchinina＇s（1987）classification,these fossils fall into 5 families of 2 orders,belonging to two classes.Two questionable calcified cyanobacteria fossils,Nuia and Wetheredella,are also included,and the definitions of Hedstroemia and Ortonella,are emended.We recommend that two genera,Mitheldeania and Sphaerocodium,are abandoned. The genus Dimorphosiphonoides,which previously was ascribed to Chlorophyta,is here attributed to Cyanophyceae.