清河镇动物群各类化石的地史分布

清河镇动物群分布于华北地台北缘。建立清河镇动物群时,认为清河镇动物群包括管状化石、壳瓣状化石、球状壳化石、针状化石和近骨状类化石五个类型,并认为清河镇动物群的时代与梅树村动物群的时代相当。本文通过对清河镇动物群各类化石的分布规律和对所产化石地层的地质年代学和地层学的研究,认为不宜把针状化石和壳瓣状化石归入清河镇动物群;近骨状化石分布局限,其地史分布难以确定;管状化石出现于中元古代,至震旦纪和寒武纪大量产出,延续到奥陶纪;球状壳化石出现于寒武纪早期,至奥陶纪仍有。

GEOHISTORICAL DISTRIBUTION OF FOSSILS OF THE QINGHEZHEN FAUNA

The Qinghezhen fauna found along the north margin of the North Chinaplatform occurs in strata originally considered to be Archean, Proterozoic and earlyEarly Paleozoic in age. The fossil zone extends as long as 2000 km from Jiapigou ofsouthern Jilin Province, Kaiyuan of Liaoning Province and Pingquan and Chengdeof Hebei Province to Guyang of Inner Mongolia. Up to now more than 50 fossillocalities have been found and more than 600 pieces of microfossils taken. Studiesof the distribution of the fossils of the Qinghezhen fauna and the geochronologyand stratigraphy of the fossiliferous strata show that it is not advisable to assignthe valualar and aculeilar fossils to the Qinghezhen fauna. Paracarinachitids are oflimited distribution, scanty and cannot provide grounds for regional correlation,and their distribution in geological history are not certain. The Qinghezhen faunaincludes mainly tubular fossils and globular fossils. Tubular fossils appeared in theChangcheng Period (Middle Proterozoic), they also occurred in large numbers duringthe Ordovician. Globular fossils appeared from the Early Cambrian to Ordovician.The study on the geohistorical distribution of the fossils making up the Qinghezhenfauna is very significant for solving the tectonic evolution of the north margin inthe North China platiorm and for making a thorough study of small shelly fossilsin northern China.