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1.
本文提出和描述了产自我国西北新疆南部喀拉塔克剖面的一个牙形类新亚种Polygnathus communis gancaohuensis,并根据以前出版的信息,命名了另一个新亚种Polygnathus commuis carmanae。种系发生研究揭示了Polygnathus communis Branson et Mehl的亚种对于法门阶最上部至韦宪阶地层的划分是至关重要的。此种的carina→gancaohuensis谱系,连同发现于喀拉塔克剖面的菊石、有孔虫和腕足动物,被认为是划分杜内一韦宪阶界线的潜在的标志化石。因此,喀拉塔克剖面有可能成为全球杜内-韦宪阶界线的一个候选层型剖面。  相似文献   

2.
本文提出和描述了产自我国西北新疆南部喀拉塔克剖面的一个牙形类新亚种 Polygnathus communis gan-caohuensis,并根据以前出版的信息 ,命名了另一个新亚种 Polygnathus communis carmanae。种系发生研究揭示了Polygnathus communis Branson et Mehl的亚种对于法门阶最上部至韦宪阶地层的划分是至关重要的。此种的 cari-na→ gancaohuensis谱系 ,连同发现于喀拉塔克剖面的菊石、有孔虫和腕足动物 ,被认为是划分杜内 -韦宪阶界线的潜在的标志化石。因此 ,喀拉塔克剖面有可能成为全球杜内 -韦宪阶界线的一个候选层型剖面。  相似文献   

3.
本文系统研究了贵州独山马道剖面泥盆-石炭纪之交的牙形刺,共鉴定出6属25种(包括亚种、比较种、未定亚种)。根据牙形刺的产出情况,在该剖面自下而上可以识别出3个牙形刺带,即法门阶的Bispathodus ultimus带,杜内阶的Siphonodella isosticha带和Polygnathus communis carina带。基于详细的牙形刺材料,讨论了上述生物带的时限和范围,并与其他地区进行了对比。虽然尚未在本剖面找到泥盆-石炭系界线的标志分子Siphonodella sulcata,但综合考虑其他牙形刺的分布以及岩性变化特征,可以将泥盆-石炭系界线暂置于融县组上部白云岩段的底部。以上成果将加深对于这一层段的牙形刺面貌以及牙形刺生物带的理解,也将为开展华南泥盆-石炭系界线再研究以及泥盆-石炭纪之交的生物-环境事件研究提供借鉴。  相似文献   

4.
略阳组分布于南秦岭勉略缝合带附近,是略阳地区重要的岩石地层单元。本次研究在略阳灵岩寺南部剖面的略阳组获得牙形刺13枚,共识别出3属5种,包含2亚种和2未定种,分别为:Siphonodella homosimplex,Polygnathus communis communis,Po.inornatus inornatus,Po. sp.和Pseudopolygnathus sp.。该牙形刺组合可以与华南同时期牙形刺进行对比,时代为早石炭世杜内期早期,这为确定略阳组的下部层位的具体时代提供了新的牙形刺证据。略阳组中所产出的Si.homosimplex为华南地区浅水相牙形刺的典型代表,Po.inornatus inornatus广泛见于西欧的浅水相地层,这表明在早石炭世期间勉略地区为浅水碳酸盐岩台地沉积环境,且与华南地区生物区系存在紧密联系,同前人根据底栖生物化石研究得出的结论相一致。  相似文献   

5.
广西天等把荷剖面下泥盆统埃姆斯阶产较丰富的Polygnathus属牙形刺化石。经详细鉴定,共识别出Polygnathus inversus,Pol.gilberti,Pol.laticostatus,Pol.linguiformis bultyncki,Pol.nothoperbonus,Pol.perbonus,Pol.serotinus,Pol.vigierei等11种(含1个未定种和2个相似种)。根据牙形刺的特征和地层分布,自下而上划分为3个牙形刺带,即nothoperbonus带、inversus带和serotinus带。在系统分类研究的基础上,根据剖面中牙形刺产出层位及齿台口面和反口面特征分析,Pol.serotinus可能由Pol.vigierei通过外齿台边缘的抬升、外侧近脊沟的变宽变深以及齿台前缘的逐渐平行演化而来,Polygnathus属反口面基腔翻转的特征最早出现在Pol.nothoperbonus演化阶段。  相似文献   

6.
本文报道了在桂东仁义剖面中上泥盆统巴漆组中一段八十余米厚地层中发现的牙形石3属10种(包括亚种)和腕足动物16属17种(包括属种未定类型).根据牙形石的组合分布,识别出Schmidtognathus hermanni带、Polygnathus cristatus带和Klapperina disparilis带上亚带,表...  相似文献   

7.
广西宜山浅水相区的一个泥盆系-石炭系界线层型剖面   总被引:4,自引:1,他引:3  
1979年,国际地科联泥盆系-石炭系界线工作组决定,泥盆系-石炭系界线应以Siphonodella praesulcata至S.sulcata的连续演化系列中S.sulcata首先出现为准。1983年,西班牙马德里会议上,泥盆系-石炭系界线工作组推荐如下四个剖面作为国际泥盆系-石炭系界线层型的候选剖面:Hasselbachtal(联邦德国1),Kija(苏联),Berchogur(苏联)和睦化(中国)。睦化剖面是熊剑飞、王成源在1980年1月测制的。1983年4月,侯鸿飞等介绍给国际泥盆系-石炭系界线工作组时,认为剖面是连续的灰岩沉积。笔者  相似文献   

8.
新疆准噶尔盆地北缘铁尔斯哈巴合地层剖面构造简单并含有丰富的晚渐新世及早中新世哺乳动物化石.其中铁尔斯哈巴合组及索索泉组沉积基本连续,两组界线位于剖面米距33 m处.依据该剖面中8个层位和相邻的XJ99005剖面中18个层位上采集的化石以及它们的上下关系和生物组合性质,划分出5个哺乳动物组合带,其中两个位于铁尔斯哈巴合组中(铁-Ⅰ,Ⅱ带),3个在索索泉组下部(索-Ⅰ,Ⅱ,Ⅲ带).从剖面的铁尔斯哈巴合组、索索泉组和哈拉玛盖组中以0.5 m的间距采集了348组古地磁样品,获得的磁性剖面包含了16个正向带和16个反向带(事件),其中包含了相当于地磁极时间表中C7n~C5E段的完整磁极带.铁-Ⅰ~Ⅱ带与塔本布鲁克哺乳动物群相近,为中国已知位置最西、构成门类和数量最多的一个晚渐新世哺乳动物组合.索-Ⅰ带应为中国目前所知的最晚渐新世的哺乳动物带.早中新世索-Ⅱ带与谢家动物群和蒙古中部渐新世-中新世过渡带D带可以对比.早中新世索-Ⅲ带相当于过去使用的"索索泉动物群",时代大致与乌尔图动物群相当.根据地磁极时间校正,铁尔斯哈巴合剖面中铁尔斯哈巴合组和索索泉组跨越了从24.5 Ma(地磁极时带C7n.2n)到18 Ma(地磁极时带C5Dr.2r)大约6.5 Ma的时间,岩体平均沉积速率大约为2.5 cm/千年.剖面中5个生物组合带的时间跨度大致分别为:铁-Ⅰ带:24.4~24.15 Ma;铁-Ⅱ带:23.2~23.1 Ma;索-Ⅰ带接近但还未到达渐新世/中新世界线的23.03 Ma;索-Ⅱ带:21.9~21.7Ma;索-Ⅲ带:21.68~21.15 Ma.我们推荐将铁尔斯哈巴合剖面作为中国区域年代地层单位谢家阶(期)底界界线层型的一个候选剖面.与谢家阶底界相对应的界线暂定在剖面由底向上40.25 m处,对应于地磁极时带C6Cn.2n底界.该界线位于索索泉组内部,索-Ⅰ和索-Ⅱ带之间.根据定义,该界线也分别对应于阿基坦阶、中新统以及新近系的底界,年龄为23.03 Ma.文章还讨论了下列问题:1)索索泉组的绝大部分应当和谢家阶以及山旺阶地层对比,仅其底部含有索-Ⅰ带化石组合的部分可与塔本布鲁克阶地层对比.2)在进行生物地层对比时尽量使用不同的索索泉组哺乳动物组合带,传统的"索索泉动物群"仅大体相当于索-Ⅲ带.3)许多过去认为的渐新世哺乳动物分子的生存时代实际上延伸到了早中新世,仅以这些分子的存在,不能说明一个动物群及其地层的确切年代.4)塔本布鲁克动物群及相关的期、阶名为有效名称,具有合法性;该阶底界有待确立.5)如果山旺阶底界(谢家阶顶界)位于地磁极时带C6An.1r底,年代为20.43 Ma,相应的界线应位于铁尔斯哈巴合剖面89.25 m处,因此,铁尔斯哈巴合剖面中有可能产生谢家阶的单位层型,该阶的地质时间跨度为2.6 Ma.6)5个生物带都是以兔形类、啮齿类以及食虫类等小哺乳动物为主要分子,而且同门类的属种间具有相当近的演化关系,说明这个地区从晚渐新世到早中新世的一段时期中,动物群性质没有明显变化,总体上反映了一个从早渐新世以来就比较干旱的环境;渐新世和中新世动物群成分在种一级上仍有明显差异;而相当于谢家动物群的索-Ⅱ带则带有明显的过渡性质.7)从索索泉组的岩性、分布的地理部位以及与甘肃秦安剖面相近的时代和动物群等来看,不排除含有风成沉积物的可能.  相似文献   

9.
采用“图式对比”方法对西南地区假希瓦格类109种(亚种)的地层分布进行了研究,计算了这些种(亚种)的区域性地层分布延限,论述了该地假希瓦格类的地层分布规律,并根据其主要属种的地层分布初步建立了西南地区马平阶的“复合标准剖面”。研究结果表明,西南地区有关剖面马平阶底、顶界线的类生物地层对比存在较大的误差。建议以贵州紫云扁平剖面作为我国马平阶的层型剖面  相似文献   

10.
古地磁测年表明,甘肃董湾晚新近纪剖面代表了7.3~3.5 Ma间的连续风成古土壤堆积。在74.8 m厚的剖面上,发现了小哺乳动物化石层位40个,共产出小哺乳动物39种。根据小哺乳动物组合特点,董湾剖面可以划分出4个生物地层带,Ⅰ+Ⅱ带为晚中新世晚期,相当于保德期;Ⅲ+Ⅳ带为上新世早期,相当于榆社期早期。中新统/上新统界线(5.33 Ma)位于剖面距顶部35.5 m处,比以鼢鼠Mesosiphneus最早出现为标志的生物地层Ⅲ带的底界低2 m。由于榆社阶底界直接对应于中新统/上新统界线,该剖面因其良好的地层和生物条件可被推荐为榆社阶界线层型的候选剖面。  相似文献   

11.
《Geobios》2014,47(6):389-401
The conodont faunas of Tournaisian shallow-water carbonates from central Guangxi are described mainly for biostratigraphic purposes. A complete series of samples was collected from the Long’an and Du’an formations in the Long’an section. These formations are characterized by lime-mudstone, skeletal and peloidal wackestone, packstone and grainstone with typical shallow-water biota. Overall, these samples produced 809 identifiable Pl elements, belonging to 50 species in 11 genera, of which one species and one subspecies are new. The fauna enables the establishment of seven biozones (in ascending order): Polygnathus spicatus, Siphonodella homosimplex, S. sinensis, S. dasaibaensis, Polygnathus communis carina Acme, Gnathodus cuneiformis, and P. communis porcatus zones. Based on these new collections from central Guangxi and on data from the literature, a conflated Tournaisian conodont zonation is proposed for shallow-water successions in South China. Most of the conodont zones correlate well with their counterparts recognized in Western Europe, which may be of greater significance in stratigraphic correlation than previously thought.  相似文献   

12.
This paper summarizes the results of investigations carried out in the Mokrá quarry since 2006 on the biostratigraphy of the Tournaisian-Visean (T-V) boundary interval. It also integrates previous results obtained by J. Kalvoda and collaborators. The main focus is on the boundary itself, but stratigraphically lower and higher levels have been investigated as well to provide a biostratigraphical context spanning the late Tournaisian to early Visean. This stratigraphical level has been the focus of intense international research in the recent years under the auspices of the Subcommission on Carboniferous Stratigraphy (SCCS) in order to find a new criterion and reference section (Global Stratotype Section and Point, GSSP) for the base of the Visean Stage. The appearance of Eoparastaffella simplex from its ancestor E.ovalis” and the Pengchong section (Guangxi, southern China) have recently been proposed by the Task Group on the Tournaisian-Visean Boundary and ratified by the SCCS as the new biostratigraphic criterion and GSSP for the base of the Visean, respectively. The sequence exposed in Mokrá is not suitable as a GSSP, notably because it is an active quarry, but it contains most of the foraminifer and conodont guides allowing a high-resolution biostratigraphy of the boundary interval. In addition, it contains abundant trilobites. For these reasons, it constitutes one of the best sections across the T-V boundary in Europe and can serve as a useful additional reference.  相似文献   

13.
Middle Devonian conodonts from the Si Phai section in NE Vietnam are described. The section ranges from the Middle Devonian ensensis to timorensis conodont zones to the Late Devonian rhomboidea conodont Zone. A rich overall assemblage is described, including 27 taxa of species or subspecies rank and 11 taxa described in an open nomenclature. Among the dominant Polygnathus forms, four new taxa are described: Polygnathus linguiformis saharicus subsp. nov., Polygnathus linguiformis vietnamicus subsp. nov., Polygnathus rhenanus siphai subsp. nov., and Polygnathus xylus bacbo subsp. nov. Conodont assemblages are attributed to polygnathid, polygnathid-klapperinid, and klapperinid conodont biofacies representing hemipelagic to pelagic environments. The klapperinid biofacies, unreported in the previous literature, are here attributed to offshore areas of the external shelf. The taxonomic compositions of the studied conodont assemblages, as well as their CAI characteristics (CAI 4–5), suggest a palaeogeographic affinity of the studied strata to the Chinese Devonian Guangxi Basin, and the South China Terrane in general. Furthermore, the conodont biofacies and the palaeogeographic distribution of the fauna are discussed.  相似文献   

14.
The genus Juniperus L. (Cupressaceae), an aromatic evergreen plant, consists of up to 68 species around the world. We classified five species of Juniperus found in Iran using molecular markers to provide a means for molecular identification of Iranian species. Plants were collected (three samples of each species) from two different provinces of Iran (Golestan and East Azarbayejan). The DNA was extracted from the leaves using a Qiagen Dneasy Plant Mini Kit. Amplification was performed using 18 ten-mer RAPD primers. Genetic distances were estimated based on 187 RAPD bands to construct a dendrogram by means of unweighted pair group method of arithmetic means. It was found that J. communis and J. oblonga were differentiated from the other species. Genetic distance values ranged from 0.19 (J. communis and J. oblonga) to 0.68 (J. communis and J. excelsa). Juniperus foetidissima was found to be most similar to J. sabina. Juniperus excelsa subspecies excelsa and J. excelsa subspecies polycarpos formed a distinct group.  相似文献   

15.
16.
A new conodont species, Polygnathus postvogesi sp. nov., from the Tournaisian deepwater deposits of the northern Urals, southeastern part of the Chernyshev Ridge, and central Pai-Khoi is described. The new species continue the phylogenetic lineage of the Late Devonian polygnathid P. marginvolutus Gedik, P. vogesi Ziegler.  相似文献   

17.
New conodont species of the genus Polygnathus from the Upper Famennian of the Urals and Cis-Urals are described. Po. tsygankoi sp. nov. is distributed from the expansa‑praesulcata conodont zones. This species occupies an intermediate position in the phylogenetic lineage Polygnathus atasuensis–Po. tsygankoi sp. nov.–Po. lobatus sensu Kononova. Po. serriformis sp. nov. is known from the praesulcata Zone. Evolutionary relationships of Po. serriformis sp. nov. are unknown.  相似文献   

18.
This project tested whether, and how, man-made changes in the environment would affect the boundary between parapatric-related taxa of Laudakia ( Reptilia: Agamidae ), whose distributions meet at a boundary between ecological regions. Israel is ecologically diverse with a mesic (Mediterranean) north and an arid (Saharo-Arabian) south. The lizard hardun Laudakia stellio is represented in Israel mainly by two subspecies: the Mediterranean Lau . s . ssp. and the desert Lau. s. brachydactyla . These are conventionally distinguished by the key character, number of subdigital lamellae under the fourth toe, visible in museum specimens examined for the purpose. The results revealed that during 1935–1978, the boundary between the two subspecies had shifted 15 km southwards. This is interpreted as resulting from the documented southwards spread of irrigated agriculture. During this time, the average subdigital count of each subspecies near the inter-taxa boundary shifted slightly towards the average of the other subspecies. In each subspecies, in this area, at the same time, the coefficient of variation of the subdigital count increased. The last two processes are interpreted as reflecting reciprocal migration, enhanced by the documented expanded road system and intensified human transportation. Hence, in this case, anthropogenic developments have changed both the location and the genetic structure of the boundary between two parapatric taxa.  相似文献   

19.
We study conodonts from the upper part of the Shizhou Member of the Yujiang Formation in Liujing area for the first time. Relatively abundant conodonts were collected from six sampling levels located between the uppermost part of the Shizhou Member to the lowermost part of the Daliancun Member at the Shizhou section, Liujing, Guangxi. The material includes Polygnathus excavatus excavatus Carls and Gandl, P. excavatus ssp. 114 Carls and Valenzuela-Ríos, P. nothoperbonus Mawson, P. perbonus (Philip) as well as ?Ozarkodina? midundenta (Wang and Ziegler) and ?O.? prolata Mawson. The lowest record of P. nothoperbonus is documented 0.35 m below the boundary between the Shizhou and Daliancun members. Correlation of conodont biostratigraphy between the Shizhou and Liujing sections indicates that the upper part of the Shizhou Member (partially) belongs to the excavatus Zone and the Daliancun Member belongs to the nothoperbonus Zone.  相似文献   

20.
《Palaeoworld》2021,30(4):659-676
The lower/upper Emsian boundary witnessed prominent diversification of biostratigraphically important genera Polygnathus Hinde, Caudicriodus Bultynck, and Latericriodus Müller. In contrast, conodonts previously reported around this boundary from the South China Block were characterized by relatively low species or subspecies diversity, and only a few widely distributed and extensively studied zone-defining taxa were recorded. In this paper, conodonts from the Daliantang Formation at the Daliantang section (Guangnan, southeastern Yunnan), one of the representative sections of the transitional facies between the benthic Xiangzhou facies and the pelagic Nandan facies, are investigated. The conodont fauna shows a remarkably high species or subspecies diversity, with fourteen taxa that are assignable to the notoperbonus Zone and inversus Zone. Five polygnathid species are described: P. gronbergi Klapper and Jonson, P. inversus Klapper and Jonson, Polygnathus sp. B, P. luciae Martínez-Pérez and Valenzuela-Ríos, and P. mashkovae Bardashev. The latter two are reported for the first time from the South China Block. Additionally, three icriodontid taxa are also described, of which L. guangnanensis n. sp. is characterized by distinctly chevron-shaped transverse rows in the anterior part and a well-developed process branching off to the outer side. The new conodont record increases our understanding of the diversification and faunal composition around the lower/upper Emsian boundary in the South China Block. It contributes to the regional and inter-regional biostratigraphical correlation between shallower- and deeper-water facies and also furnishes important South China material for future discussion and deliberation on the position of the lower/upper Emsian boundary.  相似文献   

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