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1.
根据近来的发现,区域地层的阐明及生物在寒武系界线上下的变化,澄江早寒武世地层划分作了修订。早寒武世岩石地层名称的更换,年代地层及生物地层单位的分带这里作了简述.目前的岩石地层单位从上到上是渔户村组(梅树阶),黑林铺组(筇竹寺阶),红井哨组、乌龙箐组(沧浪铺阶)及山邑村组(龙王庙阶)。此层序可分为2个亚带。所有的组合带在中国西南地台区都有存在,但两个亚带在澄江是区域性的。云南东部震旦系与寒武系的界线暂时置于渔户村且小歪头山段的底界,位于小壳化石最早出现的下部。中国的Parabadiella,摩洛哥的Abadiella及澳大利亚的Abadiella huoi这里重新作了研究。Parabadiella及Abadiella是两个不同的属。模式标本的图片在这里再次刊出。澳大利亚的Abadiella huoi一种应是Wutingaspis的一个新种(Wutingaspis jelli Chang sp.nov)。Opik(1975)的Dolerolenus(?)sp.nov.一种应归属Parabadiella huoi一种。Parabadiella是中国也是澳大利亚寒武系最古老的三叶虫。澳大利亚的Wutingaspis jelli的层位与摩洛哥Abadiella的层位相当,可与中国的Wutingaspis-Eoredichia带的上部对比。  相似文献   

2.
《Palaeoworld》2016,25(3):333-355
The Yangtze platform of South China offers evidence within its Ediacaran–Cambrian geological record of the Cambrian explosion and diversification events in metazoan history. To understand the explosive radiation of animals and the environments in which it took place, the basal Cambrian fauna succession of the Aijiahe section in the Three Gorges area, western Hubei Province, has been studied, revealing the earliest brachiopod fauna (Tsunyidiscus trilobite Zone) in this region, which was dominated numerically by acrotretoids. This is accompanied by abundant skeletal fossils including minute well-preserved phosphatized archaeocyath cups and an assortment of abundant sponge spicules, chancelloriids, mollusks, hyoliths, and bradoriids, retrieved by acid-etching limestone interbeds in the black shale-dominated Shuijingtuo Formation (Series 2). The brachiopods comprise two species of acrotretoids, two types of botsfordiids (Botsfordiidae gen. et sp. indet. A and B), and four species of linguloids. Of the latter, Spinobolus popovi n. gen. n. sp. is strikingly distinctive and typified by spine-like ornamentation seen for the first time in the lower Cambrian; the remaining three linguloid genera, Palaeobolus, Eoobolus, and Lingulellotreta, have a trans-paleocontinental distribution. The Three Gorges Shuijingtuo brachiopod assemblage differs from that of the upper Atdabanian Stage (Cambrian Stage 3) in Siberia and South China, but shows great similarities with those discovered in the Tsanglangpuan (equivalent to Botoman or Stage 4) Stage of eastern Yunnan Province, Siberia, and South Australia, suggesting a much more prolonged sedimentary hiatus in basalmost Shuijingtuo Formation of the Three Gorges area than previously expected. The presence of such unconformities provides a caveat to stable isotope-based correlations that involve a number of discussions of global ocean geochemical changes across the time interval that witnessed Cambrian explosion of metazoans.  相似文献   

3.
4.
黔东早—中寒武世凯里组疑源类组合及其界线意义   总被引:13,自引:0,他引:13  
通过对台江八郎和丹寨两条剖面凯里组中疑源类化石的分析,研究,台江剖面产疑源类化石有17属35各(12未定种),其中以Leiosphaeridia,Synsphareidium,Cymatiosphaera,Pterospermella最为丰富,可划分为3个组合,即Cymatiosphaera cf.cristata-Fimbriaglomerella memebrancea组合,Cristallinium-Micrhystridium-Pterospermella组合和Dictyotidium-Granomarginata组合,丹寨平寨剖面凯里组所产疑源类化石有:13属21种(5未定种),同样划分为3个组合,即Leiosphaeridia-Tasmanites组合,Retisphaeridium-Micrhystridium tentatium组合和Baltisphaeridium-Bubomorpha hunjiangensis组合,本文对两条剖面中的凝源类化石的组成,相对含量做了详细的统计,发现在八郎剖面9-2层和平寨剖面3层疑源类的丰度,分异度开始发生明显的变化,表现由早寒武世向中寒武世疑源类组合面貌的转变,这一疑源类转变层位正好是与三叶虫划分的中,下寒武统界线的层位位置相一致,这充分表明疑源类化石可作为划分中,下寒武统的极有价值的微体生物化石证据。  相似文献   

5.
A well preserved Ediacara-type fauna was recorded for the first time a few years ago from the bases of seven sandstone beds in the type section of the Lower Palaeozoic Booley Bay Formation in County Wexford, Ireland. Four microfossil samples from mudstones interbedded with the sandstones yielded an acritarch microflora considered indicative of a late Late Cambrian age for the Ediacara fauna, thus suggesting extension of its range from the Neoproterozoic to the Late Cambrian, rather than to the Middle Cambrian as had been previously suggested. The current study examines the microfossils in more detail, with 18 samples, all of which were productive. One additional Ediacara bed approximately 100 m above those recorded earlier was also observed. The exceptionally well preserved acritarch assemblages indicate a clear Middle Cambrian age for the Ediacara beds, thus predating the previously suggested upper limit for Ediacara faunas. The uppermost part of the formation, above known occurrences of Ediacara beds, is younger; that is, early Late Cambrian, probably coeval with the Olenus trilobite zone. In addition, the age now proposed for the Booley Bay Formation shows that it is part of the Lower Palaeozoic Ribband Group of southeast Ireland, and not part of the Cahore Group as has recently been suggested by the Irish Geological Survey. Thirty-seven acritarch species (or species groups) are distinguished and illustrated. One new species, Stellechinatum ? mariatheresae Vanguestaine, is established.  相似文献   

6.
新疆乌什下寒武统肖尔布拉克组软舌螺化石   总被引:2,自引:1,他引:1  
首次描述了采自新疆乌什县乌什磷矿肖尔布拉克组中部Kepingaspis-Tianshanocephalus带中的2个软舌螺新种Conotheca xinjiangensis sp.nov.,Nitorcornus wushiensis sp.nov.和下部Ushbaspis带中的1个软舌螺未定种Adyshevitheca?sp.。这些软舌螺化石材料为研究新疆乌什地区下寒武统中部地层与邻区相当层位的对比提供了新的证据,认为肖尔布拉克组中部2个三叶虫化石带和其中的软舌螺化石相当于我国扬子地台下寒武统沧浪铺阶中部,即乌龙箐亚阶和红井哨亚阶之间,可与俄罗斯西伯利亚和哈萨克斯坦下寒武统波特姆阶(Botomian)中的三叶虫带Ushbaspis和软舌螺带Erraticornus-Nitorcornus带对比。  相似文献   

7.
The Global Standard Stratotype-section and Point (GSSP) of the Furongian Series (uppermost series of the Cambrian System) and the Paibian Stage (lowermost stage of the Furongian Series), has been recently defined and ratified by the International Union of Geological Sciences (IUGS). The boundary stratotype is 369 metres above the base of the Huaqiao Formation in the Paibi section, northwestern Hunan Province, China. This point coincides with the first appearance of the cosmopolitan agnostoid trilobite Glyptagnostus reticulatus, and occurs near the base of a large positive carbon isotopic excursion (SPICE excursion).  相似文献   

8.
The Luoyixi section, exposed in a roadcut along the Youshui River (Fengtan Reservoir), Guzhang County, Hunan Province, China, is proposed as the stratotype for the base of an unnamed stage boundary (base of the Cambrian stage provisionally termed Stage 7). The proposed position of the GSSP is 121.3 m above the base of the Huaqiao Formation, at a horizon coinciding with the first appearance of the cosmopolitan agnostoid trilobite Lejopyge laevigata. The section fulfills all the requirements for a GSSP, and the horizon can be constrained not only with the primary stratigraphic marker (L. laevigata) but also with secondary biostratigraphic, sequence-stratigraphic, and chemostratigraphic correlation tools. The first appearance of L. laevigata is one of the most readily recognizable levels in the Cambrian, and can be correlated with precision to all paleocontinents.  相似文献   

9.
A new trilobite, Longaspis paiwuensis n. gen. n. sp., from the Balang Formation (Cambrian Stage 4) in northwestern Hunan, South China, is described. This rare trilobite adds to an expanding taxonomic list of organisms recognized from the Balang Lagerstätte, a deposit of exceptional preservation from the Cambrian. Longaspis paiwuensis is an unusually large-sized, micropygous oryctocephalid trilobite that has proparian facial sutures, pit-like lateral glabellar furrows, up to 17 thoracic segments, and a distinct medial notch in the pygidium; it lacks marginal spines.The classification of the family Oryctocephalidae is reviewed. Three subfamilies are recognized, and Longaspis n. gen. is assigned to the subfamily Oryctocarinae.  相似文献   

10.
本文描述了陕西镇巴下寒武统水井沱组中的小壳化石3新属5新种。样品采自镇巴小洋坝曾家坡,共生化石有三叶虫、古介形虫、海绵骨针和大量软舌螺等。化石组合面貌表明其地质时代属筇竹寺期。另外,在峡东水井沱组中发现了微网虫(Microdictyonsp.)化石骨片(图版I,图18,19),可与云南筇竹寺组及陕南水井沱组对比,说明Microdictyon广泛分布于扬子地台区。  相似文献   

11.
Global records of Early Cambrian acritarchs from the Skiagia plexus reveal that they are stratigraphically significant and can be used as biostratigraphic markers. Skiagia ornata and Skiagia ciliosa have a cosmopolitan distribution and the levels of their first appearance datums are proposed to serve as biostratigraphic horizons for interregional correlation. These levels are close to the lower boundary of the undefined Cambrian Stage 3, and within the Stage 3, respectively. The acritarch assemblage diagnostic of the Heliosphaeridium dissimilare-S. ciliosa Zone of Baltica is recorded worldwide and some species are traced on four of the Cambrian continents that include South Australia, South China and Laurentia. This supports the intercontinental correlation of certain Lower Cambrian strata and establishes the time equivalence between the regional trilobite zones to which these strata are attributed. The regional zonation is briefly reviewed for the purpose of comparing and evaluating the acritarch ranges. The biostratigraphic correlation of the Lower Cambrian strata, belonging to different faunal provinces, is based for the first time on the same fossil species, which have a cosmopolitan distribution and well-defined first appearance datums, and on the entire diagnostic acritarch assemblages.  相似文献   

12.
The association of isolated remains of lobopods with a netlike structure, including plates of Microdictyon rozanovi sp. nov. and sclerites with spinelike process of Onychomicrodictyon spiniferum gen. et sp. nov., as well as saberlike sclerites of Protohertzina yudomica sp. nov. interpreted as grasping spines of chaetognaths, is described from the middle part of the Inikan Formation of the Toyonian Stage of the Lower Cambrian (Lermontovia dzevanovskii Zone). The diagnoses and species composition of the genera Microdictyon and Protohertzina are refined.  相似文献   

13.
三叶虫是寒武纪演化动物群中最引人注目的成员之一,其内部解剖结构一直以来受到广泛关注.与其他非生物矿化软体结构相比,三叶虫的消化系统更容易留下化石记录,为探索其内部结构提供了难得的机会.本文描述了来自山东省潍坊市寒武系馒头组的Proasaphiscus,Lioparia,Deiradonyx和Iranoleesia,以及...  相似文献   

14.
《Annales de Paléontologie》2017,103(4):271-281
Additional Cambrian Series 3, Stage 5, trilobite fauna comprising Peronopsis sp., Eosoptychoparia cf. Spinosa Gaotanaspis cf. pingzhaiensis and Gaotanaspis cf. transversa have been recorded just immediately above the known Oryctocephalus indicus biozone (Cambrian Series 3, Stage 5) in the Parahio valley section (Spiti region). The FAD of Peronopsis and LAD of Gaotanaspis are used to establish a PeronopsisGaotanaspis concurrent biozone immediately above the Oryctocephalus indicus biozone. The first records of Gaotanaspis cf. pingzhaiensis and G. transversa from the Cambrian of Spiti region and the other faunal elements are correlated with the Peronopsis taijiangensis biozone of the Kaili Formation (South China). The stratigraphic thickness from the base of the O. indicus biozone to the top of the PeronopsisGaotanaspis concurrent biozone in the Kunzam La (=Parahio) Formation and its comparison to the Kaili Formation (South China) indicate a possible stratigraphic condensation in the basal part of the Cambrian Series 3, Stage 5 of the Parahio valley (Spiti). Sedimentological and sequence stratigraphic analysis supports this contention.  相似文献   

15.
《Comptes Rendus Palevol》2019,18(3):298-305
Refinement of the Cambrian biozonation in the Parahio valley, Spiti region (Himalaya) leads to the demarcation of the stratigraphic distance between the Haydenaspis parvatya level (Series 2, Stage 4) and the Oryctocephalus indicus Biozone (base of the Miaolingian Series, Wuliuan Stage), which has been a subject of debate. The present work suggests that these two trilobite beds in the Kaltarbo section are separated by 183.4 m of strata. Whether either taxon ranges beyond the beds they are found in this section or others in the Parahio Valley is yet unknown.  相似文献   

16.
贵州遵义松林中南村黑沙坡下寒武统牛蹄塘生物群下部层位产有大型三叶虫,计有2属3种,1未定种:Zhenbaspis subconica S. G Zhang in Lu et al. , 1974, Z. longa Zhou in Lee et al. , 1975 ; Zhenbaspis sp. , Runnania similis Lee in Yin et Lee, , 1978, 确认 Zhenbaspis (Zhenxiongaspis) Lin et Yin in Yin et Lee, 1978,为 Zhenbastn‘sChang et Chu in Lu et al. ,1974的同义名。探讨Zhenbaspis的古地理分布及演化趋势。论文还描述与Zhenbaspis,Runnania共生的Tsunyidiscus及Mianxiandiscus,其中Mianxiandiscus产于下生物群即牛蹄塘组近底部,再次证实牛蹄塘下生物群的时代早于澄江生物群。  相似文献   

17.
Carbon and oxygen isotopes were studied in fossiliferous Cambrian carbonates in northwestern Hunan Province (South China) and in northern Anhui and southern Shandong provinces (North China). Two major C isotope excursions related to biological events occur in the Wangcun section (Yongshun County, northwestern Hunan), which consists of a slope carbonate sequence (510 m thick) containing abundant trilobites. The first C isotope excursion (δ13C value shifts from -2.3‰ to 2‰) occurs near the boundary between the Qingxudong and Aoxi formations, close to the traditional Lower-Middle Cambrian boundary. The second excursion (δ13C value shifts from 0‰ to 3‰) occurs in the interval between the Linguagnostus reconditus Zone and the Glyptagnostus reticulatus Zone. The base of the G. reticulatus Zone define the base of the Paibi Stage and Furongian Series. Similar C isotope excursions also occur in shallow - water carbonate sections in North China. In Jiagou section near Huainan (Anhui Province), recently considered an important interval for defining the lower-middle Cambrian boundary because of dramatic changes in the trilobite fauna (extinction of redlichiids and appearances of ptychopariids), a negative C isotope excursion (δ13C value shifts from +1.21‰ to -1.93‰) occurs at the top of the lower member of the Mantou Formation. In the Gushan section (Changqing County, Shandong Province), a C isotope excursion (δ13C value shifts from -0.04‰ to 2.23‰) occurs at the base of the Changshan Formation and is coincident with the base of the Chuangia Zone. This excursion can be correlated with the excursion in the lower part of Glyptagnostus reticulatus Zone in the Wangcun section. The above two distinct C isotope excursions, which occur both in slope carbonates in South China and in shallow - water carbonates in North China, have also been recognized in Cambrian sections on other continents, and they coincide with global mass extinctions of trilobites. The two excursions evidently reflect global changes of Cambrian sea level, and they have utility for Cambrian subdivisions and for both regional and global stratigraphic correlation. In addition, a negative carbon excursion below the base of the Ptychagnostus atavus Zone in the Wangcun section supports previous suggestions that the FAD of P. atavus can be considered as a global correlatable horizon within the middle Cambrian.  相似文献   

18.
《Palaeoworld》2008,17(2):108-114
The base of the Guzhangian Stage (Cambrian) has been ratified recently at the lowest occurrence of the cosmopolitan agnostoid trilobite Lejopyge laevigata (base of the Lejopyge laevigata Zone) in the Huaqiao Formation in the Luoyixi section, Guzhang County, Hunan Province, China.Sampling of the Luoyixi section in the boundary interval reveals 16 protoconodont and paraconodont taxa. The conodont succession can be correlated with the Gapparodus bisulcatus-Westergaardodina brevidens and the Shandongodus priscus-Hunanognathus tricuspidatus zones of South China and with the Laiwugnathus laiwuensis and the Shandongodus priscus zones of North China. Laiwugnathus laiwuensis occurs immediately below the lowest occurrence of Lejopyge laevigata. The first occurrence of Shandongodus priscus is 14.95 m above the base of the Lejopyge laevigata Zone. A significant change in the conodont associations occurs in the interval corresponding to the uppermost Lejopyge armata trilobite Zone. This interval is characterized by an increase in diversity with the appearance of the paracondont genera Furnishina and Laiwugnathus. Laiwugnathus laiwuensis, which occurs immediately below the lowest occurrence of Lejopyge laevigata, has a short stratigraphic record and allows confident correlation with North China.  相似文献   

19.
河南叶县下寒武统辛集组单板类和腹足类化石的研究   总被引:5,自引:3,他引:5  
本文描述和讨论了河南叶县杨寺庄下寒武统辛集组单板类13种,腹足类2种,未定类1种。其中包括2新属6新种:Repenoconus xinjiensis gen.nov.,Scenella pycna sp.nov.,Securiconus vulgaris sp.nov.,Obtusocnus grossicostus sp.nov.,Igorellina proboscis sp.nov.,Gal  相似文献   

20.
The Middle to Upper Cambrian Machari Formation in Korea is well known for abundant and diverse trilobites along with other invertebrate fossils. Based on recent reappraisal on the trilobites of the Machari Formation, eight trilobite zones have been proposed for the Upper Cambrian sequence: i.e., in ascending order the Glyptagnostus stolidotus, Glyptagnostus reticulatus, Proceratopyge tenuis, Hancrania brevilimbata, Eugonocare longifrons, Eochuangia hana, Agnostotes orientalis and Pseudoyuepingia asaphoides zones. Trilobites from the lower five zones and part of the Pseudoyuepingia asaphoides Zone have been already published elsewhere. In this paper, we describe the agnostoid trilobites of the upper three zones, Eochuangia hana, Agnostotes orientalis and Pseudoyuepingia asaphoides zones, of the Machari Formation. These comprise 24 species belonging to 13 genera, including one new genus (Yongwolagnostus) and ten new species (Homagnostus? sulcatus, Ivshinagnostus alatus, Ivshinagnostus quadratus, Yongwolagnostus stenorhachis, Yongwolagnostus dubius, Nahannagnostus pratti, Pseudagnostus? dividuus, Pseudagnostus medius, Pseudorhaptagnostus? urceus and Ammagnostus serus). These biozones correlate well with middle Upper Cambrian zones established in South China, Australia, Kazakhstan, Siberia, and Canadian Rocky Mountains.  相似文献   

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