摘要
本文对蓟县地区长城系进行了较为系统的生物地层和生态环境研究工作,初步发现和证实在长城系中含有宏体化石5科(类)、5个属、6个种,其中1个新种和1个相似种。通过区内长城纪宏体化石的分布、层应、类型、特征和保存条件等方面的初步研究,同时结合多种分析测试手段,如化石固定炭、有机炭、红外光谱分析,电镜扫描、稳定同位素及微量元素等,初步探讨了化石成分、时代、生态环境、生物归属和地层意义等问题。长城纪串岭沟组、团山子组和高于庄组宏体化石,同位素年龄约在1800～1400Ma 之间,它们是我国目前最早的宏体化石,也可能是世界上最早的宏体化石之一。从高于庄组宏体化石与北美及印度宏体化石对比,具有大致相同时代、相同类型,表明了生物在演化上的同步性和阶段性,具有较大的地层意义。
The occurence of macroorganism is the landmark evolutionary event.According to recent discoveries,it has been proved that the megafossils are real representives of Middle and Upper protero- zoic life.But they are monotonous in form,simple in structure, lack of modern representatives and undergoing late metamorphism etc.,so up to the present each of the fossils sticks to his own stand. The Changchang System,The lower part of the Middle and Upper proterozoic Erathem,in the Jixian stratotype section,has been systematically studied by our predecessors and some megaf- ossils have been found and reported,and which were evoked wide interests and suspicion.During the last few years studies,a lot of investigations on biostratigraphy have been made for the first time: 1)New localities,horizons and forms of megafossils in the Ch- uanlinggou Formation and the Tuanshanzi Formation have been discovered.Some new and more reliable evidence on the disputation of megafossils have been given. 2)Further studies on the megafossils previously discovered in the Gaoyuzhuang Formation,and some new materials found in some new localities have proved that the fossiliferous strata are quite stable.Based on the appraisal of the forms of the megafos- sils,it has been confirmed that the genus Sangshuania from Jixi- an is an synonymous with Grypania from North America 3)By employing such examinations as isotopic dating,infrared spectroscopy,organic carbon analysis,electronic scanning,thin -sections study etc.,the composition and strucure of megafossils have been given. )The distributions,horizons,features and classification of megafossils from this region have been fully expounded in this pa- per.Five families,five genera,six species,including one confor- mis,have been systematically described and illustrated.A tenta- tive study of the ages and ecology of megafossils from each forma- tion of the Changcheng System has been carried out. 5)It has been affirmed that the age of the megafossils is from about 1800 Ma to 1400 Ma.The fossils are probably the earliest megafossils which have been found in the world. 6)The stratigraphical significance and the classification of megafossils have been preliminarly discussed.It is proposed in the paper that the megafossils of the Chuanlinggou Formation be possibly“macroalgae”,and those of the Gaoyuzhuang Formation be neither macroalgae nor trace fossils,they possibly belong to “primitive Metazoan”. 7)The correlation between Sangshuania(now Grypania)and the fossils from North America and Iadia shows the periodicity and synchronization in life evolution.Thus it is suggested that the megafossils of the Mid-proterozoic Changcheng system should be potential guide fossils.
