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通过震旦系研究历史的回顾,在前人研究的基础上,结合近年来综合地层研究的成果,试图建立可供全球对比的中国末元古系层型剖面。我国震旦系研究历史悠久,典型剖面经历南北之争,数十年来存在多种界定意见。通过近十年的研究,笔者依然认为峡东地区震旦系剖面沉积最为连续,出露完整,具有生物演化特征明显和形态多样的特点,可与世界各地的末元古纪地层进行广泛对比。目前,其上界定位于峡东地区灯影组天柱山段小壳化石带之下(即相当云南晋宁梅树村剖面震旦—寒武系界线小壳化石带B点,年龄为539±34Ma),而底界的厘定在国内一直存在多种意见。本文通过对峡东地区震旦系剖面的综合地层研究,结合生物地层学、年代地层学、层序地层学、C/O同位素研究以及沉积相等方面的综合分析,认为震旦系底界应划定在南沱冰期之后的陡山沱期沉积的下界,重申应选定峡东地区剖面为震旦系的层型剖面。 相似文献
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中国晚前寒武纪至早寒武世生物事件及前寒武系—寒武系界线 总被引:1,自引:0,他引:1
《地层学杂志》1992,(1)
<正> 35亿年前,地球上开始有生物存在,主要是兰藻和细菌。距今10亿年左右,开始出现软躯体动物所形成的遗迹化石。9亿年有蠕形动物的实体化石——淮南生物群保存。7亿年软躯体后生动物——埃迪卡拉动物群(西陵峡生物群、高家山生物群)大量繁殖,使晚前寒武纪的生物演化进入一个新阶段。6亿年左右,骨骼化动物——梅树村动物群(或托莫特动物群)的出现,开创了生物发展、演化史上的新纪元。使更多的生物能够以化石 相似文献
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Abstract There are abundant and highly varied trace fossils in the Sinian—Cambrian boundary beds in eastern Yunnan. Collections from 27 sections and their study give altogether 45 ichnogenera and 87 ichnospecies. Among them, 2 ichnogenera and 7 ichnospecies are new, and 31 known ichnogenera and 38 known ichnospecies first found in the region. According to their order of appearance in the boundary beds and their assemblage features, the trace fossils in the Sinian—Cambrian boundary beds in the region may fall into 4 trace fossil assemblage zones in ascending order. In the paper they are correlated with those in the equivalent horizons abroad and their geological significance is discussed preliminarily. 相似文献
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Contributions to a symposium of the IUGS Subcommission on Cambrian Stratigraphy at the International Geological Congress in Montreal in 1972 are the basis of this paper which is intended to give guidance to further work of what is now a Working Group on the Precambrian—Cambrian boundary of the International Geological Correlation Programme (UNESCO/IUGS). The proposed principles for the definition of the boundary are based on those accepted by the Commission on Stratigraphy, particularly on stratigraphic classification and on defining the Silurian—Devonian boundary. These matters are discussed by the authors in general terms and by W.B. Harland in terms of procedure. They are illustrated by examples of stratigraphic sequences across the boundary in Siberia given by A.Yu. Rozanov and discussed critically by V.E. Savitsky. New relevant discoveries of Early Cambrian faunas and their stratigraphic setting are reviewed by A. Boudda et al. P.E. Cloud's contribution, published elsewhere, and work in Australia are reviewed by the authors.The conclusions, based not only on the symposium material but also on current opinion, are that no single sequence which could serve as a reference standard for the Precambrian—Cambrian boundary has yet been identified but that many significant ones have been described which will be further examined. While the general limits for the choice of a boundary definition should lie between the horizons with fossils of Ediacaran type and those with diversified trilobite assemblages, a number of “Working Reference Points” exist in that interval which are correlatable horizons of faunal change. These cannot be defined simply as horizons of first appearance. 相似文献
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A. Yu. Rozanov V. V. Khomentovsky Yu. Ya. Shabanov G. A. Karlova A. I. Varlamov V. A. Luchinina T. V. Pegel’ Yu. E. Demidenko P. Yu. Parkhaev I. V. Korovnikov N. A. Skorlotova 《Stratigraphy and Geological Correlation》2008,16(1):1-19
It was a serious mistake when subdivision stratotypes had been disposed of in practice of constructing the General stratigraphic scale, because they cannot be substituted by the boundary stratotypes. A subdivision stratotype and respective GSSP are complementary parts characterizing any stratigraphic unit. The best candidates for stage stratotypes of the Lower Cambrian are certainly sections of the Lena-Aldan region in the Siberian platform, which have been studied in detail during many years, are well exposed, and contain abundant and diverse fossils, being insignificantly disturbed by tectonic dislocations. Nomenclature, stage and boundary stratotypes of the Siberian standard can be successfully used therefore for stratigraphic subdivision of the Lower Cambrian. 相似文献
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W. T. Chang 《Australian Journal of Earth Sciences》2013,60(1-2):137-150
The sedimentary history and biostratigraphy of China during the Cambrian Period are broadly discussed within the framework of major tectonic divisions of the country. Five platform domains (North China Platform, southwest China Platform, Chiangnan Belt, Tarim Platform, and Tsaidem Platform) and five eugeosynclinal belts (South Tibet‐western Yunnan Belt, Tienshan‐Altai‐Great Khingan Geosyncline, Chilian Geosyncline, Kunlun‐Tibet‐western Yunnan Geosyncline and Southeast China Geosyncline) are recognised and discussed individually. A zonal scheme for Chinese Cambrian biostratigraphy is provided and the problems of the Precambrian to Cambrian, Cambrian to Ordovician and also the series boundaries are discussed. International correlation of the Cambrian of China, especially with Australia, is outlined in some detail. 相似文献
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Exceptionally preserved fossils,such as those from Cambrian Burgess Shale-type fossil-Lagerstatten are critical because of their unique contributions to knowledge of the phylogenetic radiation and palaeoecological expansion of metazoans during the Cambrian explosion.Critically,these deposits provide information that is usually unobtainable from shelly and skeletonized fossils alone.The Guanshan Biota(Cambrian Series 2,Stage 4)in the Yunnan Province of South China,has produced abundant and diverse,exquisitely preserved fossils that often retain soft tissues and organs.To date,most fossils from the Guanshan Biota have been collected from localities such as Gaoloufang and Gangtoucun,which have become inaccessible due to new urban expansions and constructions of residential buildings.Here we present the first report of soft bodied fossils from a new section at Kanfuqing,close to the Wulongqing village in Malong County,approximately 3 km east of the Wulongqing Formation stratotype section.Fossils retain soft morphology,and include brachiopods with delicate marginal setae,priapulids with well-preserved sclerites and vetulicolians with entire sections of body.In addition,this fauna includes rare occurrences of trilobites preserved with soft tissues replicated as pyrite pseudomorphs after weathering.This discovery represents an important palaeogeographical extension of soft-bodied fossils of the Guanshan fauna to the east of the Xiaojiang Fault(related to Tsinning tectonic movements ca.700 Ma).The fauna from the new Kanfuqing section is similar to that reported from the Wulongqing Formation west of the Xiaojiang Fault,and thus has significant implications for early Cambrian palaeogeography,faunal successions and palaeoenvironments of eastern Yunnan. 相似文献
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我国早期生命进化研究的进展和展望 总被引:1,自引:0,他引:1
概述了中国在晚前寒武纪——寒武纪生物化石群研究多方面(尤其是大化石)的主要成就。其中,近年发现的震旦纪陡山沱期化石生物(包括庙河生物群和蓝田植物群),对植物界的进化说来是个重要阶段;早寒武世澄江生物群(包括软躯体生物和软部保存的带骨骼生物)早于国外著名的布吉斯页岩生物群,逼近了带骨骼动物最初的爆发式辐射期。这些珍稀化石的研究将促进对早期生物进化历程的重新认识。这个研究领域有无可限量的前景。 相似文献
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双峰具下寒武统灰绿色板岩、硅质板岩中产大量小壳动物化石,为研究湘中南地区震旦一寒武系界面划分提供了古生物资料。 相似文献
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长江三峡地区震旦系的微体植物化石 总被引:1,自引:0,他引:1
《地层学杂志》1986,(4)
<正> 1980年,笔者同余汶、钱逸、王宗哲、侯先光、赵自强等在宜昌莲沱的王丰岗,南沱至石牌村以及秭归县庙河震旦系剖面采集了岩样(图1)。莲沱砂岩和南沱冰碛层中的化石贫乏,仅发现球形疑源类Leiominuschla sp.Protoleiosphaeridium spp.以及一些微体植物残片。陡山沱组微体植物类型多样化,数量可观。有疑源类(acritarchs)的刺球亚类(Acanthomorphitae)的分子,如微刺藻(Micrhystridium),波罗地藻(Baltishaeridium)和毛发藻(Comasphaeridium)等,其中Micrhystridium的数量多至千万计。有晚前寒武纪常见的球形亚类(sphaeromorphitae)的分子外,出现许多具有各种裂口、开口及至口盖的疑源类属种,如Leiosphaeridia?operculia sp.n.,Stictosphaeridium?apertum sp.n.,Paiaeostomc cystis angoformis,Eoaperturilites monoscissus gen. et sp. n., Eo. gonostomus gen. et sp. n., Tasmanites? sp. A。 相似文献
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中国前寒武纪痕迹化石的分布及其古生物学、地层学意义 总被引:2,自引:0,他引:2
近年来,在我国前寒武纪不同时代的地层中发现了大量的痕迹化石,其中前寒武纪冰期前的痕迹化石主要分布于我国北方的长城纪和青白口纪地层中。这些痕迹化石产出时代古老,表明在我国北方14~17亿年前的海水中就可能生活有古老的后生动物,这些痕迹化石的发现对于探索后生动物的起源及演化具有重要意义。前寒武纪冰期后所发现的痕迹化石主要分布于我国西南地区震旦纪晚期的地层中,这些痕迹化石在震旦纪地层中的广泛分布,对震旦系及震旦系与寒武系界线的划分对比将提供重要依据。 相似文献
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《International Geology Review》2012,54(10):1146-1152
Differences in altitude, degree of metamorphism, radiological dating, and paleontological evidence support the claim of the existence of the Sung-yang movement represented by the unconformity between the Teng-feng complex and the overlying Sung-shan group in Western Honan. The Sinian system unconformably underlies the tillite bed in Western Honan, or, if the tillite is missing, the Early Cambrian Kuang Ko conglomerate. The base of the Sung-shan quartzite of the Sung-shan group serves as the lower boundary of the Sinian system because 1) algal fossils are found in the Sung-shan group and 2) lithologically the Sung-shan group is similar to the Lower Sinian Chang Cheng series in Yen-shan region. Other evidence convinces the author that the Sinian system represents an era or sub-era of Precambrian time, instead of what is generally considered an epoch. The tillite bed in Western Honan is Early Cambrian, consequently younger than the Sinian glacial deposits in South China. – Author. 相似文献
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A subdivision of the Precambrian of China 总被引:1,自引:0,他引:1
Precambrian rocks are widely distributed in China. The Precambrian is divided into two time units, i.e., the Archaean and Proterozoic Eon, each of these is separated into three chronological intervals, also with the status of eras, with the prefixes early, middle or late. The time boundary between the Archaean and Proterozoic Eon is placed at ~ 2500 Ma.According to the present isotopic data, the proposed subdivision for the Archaean of China is two-fold. The age of the Fuping Group is younger than 2800–2900 Ma, and that of the Qianxi Group and the corresponding stratigraphic units of eastern Liaoning are older than 2800 Ma, so that 2800+ Ma is selected as the boundary between the early—middle and late Archaean.Based on the representative stratigraphic units, the Wutai and Huto Groups, and an intervening major unconformity formed by the Wutaiian orogeny at 2200–2300 Ma, the early Proterozoic is further divided into two periods, with a time demarcation at 2200+ Ma. A major episode of orogeny known as the “Luliangian Movement” occurred at the end of the early Proterozoic at ~ 1900 Ma. This disturbance was very extensive and is, in a way, responsible for the difference in geological conditions between the lower and middle—upper Proterozoic in China. The boundary (1900 Ma) that relates to the Luliangian Movement is more important than the boundary corresponding to the age of 1600 Ma, which is recommended as the time boundary between Proterozoic I and II, so we propose to use 1900 Ma as the boundary between the early and middle Proterozoic in China.The time boundary between the middle Proterozoic, including the Changcheng System and the Jixian System, and the late Proterozoic, which is composed of the Qingbaikou and Sinian Systems, is ~ 1000 Ma. The age for the boundary between Cambrian and Precambrian, based upon the recent isochron data, is inferred to be 610 Ma. 相似文献
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M. D. BRASIER 《Geology Today》1985,1(5):141-146
Over the last decade, palaeontologists around the world have been striving to understand one of the most remarkable episodes in the fossil record: the explosive evolution of skeletal fossils around the Precambrian–Cambrian boundary. When examined in the field, the close association of geological and biological events is apparent. An important succession in this respect is the classic Precambrian and Cambrian area of Charnwood–Nuneaton in the English Midlands. Here it can be seen that the boundary also spans a time of major tectonic and oceanographic changes. Could these have contributed to the ‘Cambrian evolutionary explosion’? 相似文献
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须腕动物门(Pogonophora)皱节虫科(Sabelliditidae)的化石(图版Ⅲ,图2)在前寒武纪和寒武纪沉积内均大量发现,最近此种化石还发现于苏联的中里菲界(约11亿年),被认为是一种可靠的最古老的后生动物化石。 相似文献