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Palaeogeographic world map (adapted from SCOTESE & DENHAM 1988; Mollweide equatorial projection) illustrating the "Psigraptus Seaway", a regionally restricted shallow to open-shelf habitat in tropical latitudes during "mid" Tremadocian times. In this configuration the spreading of post-Rodinia continental plates has been estimated derived from the "AUSWUS-model" of KARLSTROM et al. (1999) and data on the Sino-Korean and Yangtze Platform palinspastic positions have been incorporated from CHOI et al, (2001). The palaeobasin outlines for Australia are adapted from GRAVESTOCK • SHERGOLD (2001) and for NW Canada from JACKSON & LENZ (2000). The locations of Psigraptus occurrences are indicated by solid dots.
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Based on a systematic study of Tremadocian graptolites from the Early Ordovician Yehli Formation at Dayangcha, Baishan of Jilin, NE China, a revised graptolite zonation is proposed for the Tremadocian rocks in the area. In ascending order, the graptolite zones include theRhabdinopora flabelliformis parabola Zone, theAnisograptus matanensis Zone, th...
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... breccias have been observed which overlie rippled surfaces, all point- ing to stormwave influenced depositional environments of an open carbonate shelf. This assessment differs somewhat from the ecostratigraphic model of COOPER (1999: fig. 4), in which a distinctly deep-water habitat was suggested for Psigraptus, whereas ERDTMANN (1988a: fig. 5) already placed Psigraptus into a "low lat- itude deep shelf to slope break" environment. Both lithologically and faunally there are striking similarities in facies between the northeastern Chinese and South Korean developments of the Yehli and Mungok forma- tions whose collective biofacies, on the other hand, is completely different ...
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... open-shelf to slope deposits and their non-pandemic palaeogeographic distribution invites a reconstruction of a potentially restricted Trem- adocian "seaway" which may have encompassed all lo- cations of psigraptids within a palaeogeographically limited series of basins -nowadays bordering far-away areas on opposite sides of the Pacific Ocean (Fig. ...
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... laeo-southern latitude for a Gondwanan "Yangtze- Block". By also bringing northwestern Laurentia into a relatively close juxtaposition with the Sino-Korea Block a "limited-size" equatorial basin would best accommo- date the palaeogeographic constraints of the original distribution of endemic psigraptids during the "mid" Tremadocian (as shown in Fig. 5). With regard to the ca. 60 Ma time span between the Latest Proterozoic and the "mid" Tremadocian (at ca. 487 Ma) the post-Rodinia break-up would support a wider opening of this "sea- way" than before. This is also reflected in the palaeo- geographic map of Fig. 5. The characteristic "endemic" distribution pattern of nematophorous, ...
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... distribution of endemic psigraptids during the "mid" Tremadocian (as shown in Fig. 5). With regard to the ca. 60 Ma time span between the Latest Proterozoic and the "mid" Tremadocian (at ca. 487 Ma) the post-Rodinia break-up would support a wider opening of this "sea- way" than before. This is also reflected in the palaeo- geographic map of Fig. 5. The characteristic "endemic" distribution pattern of nematophorous, i.e. potentially pandemic psigraptids and their narrow stratigraphic range coupled with a specific carbonate shelf biotope favours a significant biomarker role for these graptolites in the definition of a geographically limited basin during early Ordovician times. ...
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... including at Taishan in Guangdong Province (WANG et al. 1979), at Chongyi in southern Jiangxi (XIAO & XIA 1984), and near Jiangshan in west- ern Zhejiang (Mu 1955). XIAO & CHEN (1993) de- scribed some specimens from Chongyi, which they assigned to Anisograptus ruedemanni BULMAN (e. g. pl. 1 fig. 9) and Adelograptus asiaticus Mu (e. g. pl. 3 fig. 5). These specimens show, as illustrated, long isolated metasiculae and asymmetrical proximal end belonging more likely to Kiaerograptus. Some others, previously identified as A. victoriae, were not illustrated clearly, and thus remain unidentifiable ...
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Citations
... According to the morphological difference of the reclined graptolites, they had successively established four new genera and one new subgenus, which include Muenzhigraptus, Diphygraptus, Hunjianggraptus, Holpsigraptus and Neoclono graptus Zhang 1985, 1986;Zhao et al. 1988). Most scholars believe that the above five (sub-)genera and Yukongraptus Lin, 1981 are all synonymous with Psigraptus (Wang and Erdtmann 1986;Rickards et al. 1991;Maletz 1992;Wang et al. 1996;Zhang and Erdtmann 2004), while others have also classified a group of mor phologically similar graptolites as the subgenus Clonograptus (Neoclonograptus) Zhao and Zhang, 1985 into the genus Ancoragraptus (Cho et al. 2009). ...
... The base of the Upper Tremadocian is identified by the first appearance of Adelograptus tenellus (Linnarsson), as soci ated with Ancoragraptus gracilis (Zhao and Zhang). Ancoragraptus gracilis was originally defined by Zhao and Zhang (1985) as Clonograptus (Neoclonograptus) gracilis, but subsequently considered the synonym of Psigraptus jacksoni Richkards and Stait (Wang and Erdtmann 1986;Rickards et al. 1991;Maletz 1992;Wang et al. 1996;Jackson and Lenz 2003;Zhang and Erdtmann 2004). Based on the reclined rhabdosome with free metasicula and non-free metathe cae, Cho et al. (2009) assigned the subgenus Neoclonograptus to the genus Ancoragraptus Jackson and Lenz. ...
... В Горной Шории выделяются слои с Anisograptus richardsoni Bulman [14,28]. Граптолитовая зона richardsoni выделяется в ордовике Китая [97]. ...
New data are given on zonal graptolite units in the structure of the new Ordovician stage standard within the framework of the International Stratigraphic Chart. Ordovician zonal graptolite successions in the largest regions of Russia have been analyzed and correlated. Научные дискуссии о независимом параллельном или взаимодополняющем (взаимозаменяющем) использовании двух категорий хроностратиграфических шкал продолжаются уже более 50 лет. К первой категории относится Международная («глобальная» или «планетарная») шкала с ярусными подразделениями и ее российский эквивалент-Общая стратиграфическая шкала, а ко второй-реги-ональные шкалы с подразделениями, именуемыми горизонтами [44]. Инициаторами постановки этого вопроса у нас в стране и последующего его широкого обсуждения были сибирские стратиграфы, воз-главляемые тогда в ведущем отраслевом институте СНИИГГиМС Л. Л. Халфиным [3, 45-47], а в акаде-мическом Институте геологии и геофизики-Б. С. Соколовым [40-43]. Л. Л. Халфин кратко охарактеризо-вал эту проблему следующим образом: «Международная шкала-это счисление времени, хронология, а региональные схемы-это сама история, события которой датируются посредством хронологии» [45, с. 390]. Б. С. Соколов отмечал следующее: «…общая (международная) стратиграфическая шкала по сути своей может быть только синтетической (составной)… независимой от системы реальных геологи-ческих стратонов» и «региональные стратиграфические подразделения и их сопокупность в регионе-это исходная реальность…» [42]. История становления идей автономности и дополнительности стра-тиграфических шкал была недавно подробно рассмотрена А. В. Каныгиным [6]. Не вдаваясь в детали вопроса из-за ограничения объема рамками статьи, следует отметить, что методические приемы корре-ляции и их прикладное применение при сопоставлениях двух параллельных хроно стратиграфических шкал были и остаются в числе наиболее дискуссионных вопросов при пространственно-временных ре-конструкциях и обобщениях. Инстументом такой достоверной корреляции с дробностью необходимого уровня для ордовика и силура служат зональные шкалы по граптолитам и конодонтам. РЕГИОНАЛЬНЫЕ СТРАТИГРАФИЧЕСКИЕ ПОДРАЗДЕЛЕНИЯ ОРДОВИКА И ИХ КОРРЕЛЯЦИЯ С ЯРУСНЫМИ ПОДРАЗДЕЛЕНИЯМИ МЕЖДУНАРОДНОЙ СТРАТИГРАФИЧЕСКОЙ ШКАЛЫ В региональных стратиграфических схемах первый раздел состоит из подразделений соответству-ющей системы Общей стратиграфической шкалы, а второй представляет собой последовательность региональных стратиграфических подразделений с основной таксономической единицей-горизонтом [44]. Горизонты («региоярусы») в ордовике различных регионов России выделялись по комплексам бентосных групп организмов, установленных в опорных разрезах какого-либо геологического регио-на, главным образом трилобитов и брахиопод, вместе с табулятами, ругозами, остракодами и др. Это обеспечивало «внутрирегиональную коррелятивную функцию горизонта»-сопоставление разрезов по комплексам групп организмов, наиболее распространенных в регионе (палеобассейне) по латерали и встречающихся в максимальном спектре фациальных обстановок. Пелагические сообщества (грапто-литы, конодонты, хитинозои, радиолярии) вследствие неравномерной их встречаемости (как по площа-ди, так и в стратиграфическом разрезе) и немногочисленности в большинстве регионов не включались в ранг основных параметров при выделении горизонтов и рассматривались как вспомогательные для межрегиональных корреляций. Этим в какой-то мере принижалась хронометрическая функция гори-зонта-осуществление «прямых» (по одноименным зональным подразделениям) сопоставлений серий разрезов отдельного геологического региона по комплексам пелагических групп организмов с ярусными подразделениями Общей (или Международной) стратиграфической шкалы. ИННГ СО РАН (Новосибирск)
... The biota comprises acritarchs, conodonts, brachiopods, graptolites and trilobites in great variety and abundance. Erdtmann (1986), Lin ( , 1986, Wang and Erdtmann (1987), Zhang and Erdtmann (2004), Maletz et al. (2017) and studied graptolites from the section and the region. followed by Chen and Gong (1986) and Wang et al. (2019) documented the conodont succession with additional information provided by Nowlan and Nicoll (1995) and Nicoll et al. (1999). ...
... The overlying Yeli Formation (Grabau, 1922;Zhang, 1962;Wang et al., 1996;Zhang and Erdtmann, 2004;Wang et al., 2019) is composed of carbonate sedimentary rocks with subordinate shale bed (Zhang, 1962;Wang et al., 1996Wang et al., , 2019. The Yeli Formation is exposed in the other small rivulet, extending westward, immediately to the south of the Xiaoyangqiao section, along the road heading to the northeast Fig. 1B), at the Laotougou Quarry section near the village of Erdaopuzi and along the main road (Zhang and Erdtmann, 2004;Yan et al., 2019). ...
... The overlying Yeli Formation (Grabau, 1922;Zhang, 1962;Wang et al., 1996;Zhang and Erdtmann, 2004;Wang et al., 2019) is composed of carbonate sedimentary rocks with subordinate shale bed (Zhang, 1962;Wang et al., 1996Wang et al., , 2019. The Yeli Formation is exposed in the other small rivulet, extending westward, immediately to the south of the Xiaoyangqiao section, along the road heading to the northeast Fig. 1B), at the Laotougou Quarry section near the village of Erdaopuzi and along the main road (Zhang and Erdtmann, 2004;Yan et al., 2019). ...
In 2019 the Sub-Commission on the Ordovician System
approved the Xiaoyangqiao section, North China as a
new ASSP section for the base of the Ordovician System.
The sedimentary succession of the section is exposed in a
natural outcrop near the Dayangcha Village at a position
of 42°3'24''N, 126°42'21''E. It has a well-preserved, abundant
and diverse fossil record across the boundary with
key markers (conodonts and graptolites), which provide
improved intercontinental correlation of the Cambrian–
Ordovician boundary. The appearance of the first planktonic
graptolites is immediately below the base of the Cordylodus
lindstromi Conodont Zone. Other fossils, including
acritarchs, brachiopods and trilobites are also present in
the Xiaoyangqiao ASSP section. Non-biotic secondary global
markers near the base of the Ordovician System include
a positive carbon isotopic excursion with the maximum peak
(named HSS) below the boundary, a prominent unnamed
negative peak immediately below the boundary and a
prominent carbon isotope excursion with positive peaks
above the boundary. The latter excursion is associated with
the appearance of the planktonic graptolites in the Ordovician.
The strength of the Xiaoyangqiao ASSP section is
the correlation between the conodonts and graptolites,
correspondence of sea-level lowstands, and the matches
of geochemical parameters.
... Correlations between conodont and graptolite zones are facilitated by the conodont-and graptolite-bearing sections of western Newfoundland (e.g., Cooper et al., 2001a,b), southwest Sweden (Löfgren, 1993(Löfgren, , 1996, the eastern Cordillera of Argentina (e.g., Ortega and Albanesi, 2005;Zeballo et al., 2008), and Dayangcha, China (Chen, 1986, Chen et al., 1988Zhang and Erdtmann, 2004). Integrated graptolite and conodont biostratigraphy together with recent studies in stable isotope geochemistry (e.g., Azmy et al., 2014) provide a global correlation framework of high precision for the Tremadocian Stage. ...
... The fauna comprises acritarchs, conodonts, graptolites and trilobites in high variety and abundance. Erdtmann (1986), Lin (1986), Wang and Erdtmann (1987), and Zhang and Erdtmann (2004) studied the graptolites from the section. The conodonts have been documented by Chen et al. (1985) followed by Chen and Gong (1986) with additional information by Nowlan and Nicoll (1995) and Nicoll et al. (1999). ...
... The Yeli strata are composed mainly of carbonate sedimentary rocks with only subordinate calcareous shale. The Yeli Formation is exposed in the other small rivulet immediately to the south of the Xiaoyangqiao section and along the new main road (Zhang and Erdtmann, 2004;Fig. 1B). ...
The Cambrian–Ordovician boundary interval exposed at the Xiaoyangqiao section, North China is presented. The distribution of stratigraphically important fossils in the Xiaoyangqiao section revealed several nearly coeval graptolite, conodont, trilobite, and acritarch bioevents in the uppermost Cambrian–lowermost Ordovician carbonate-siliciclastic sedimentary sequence. The precise correlation to the Green Point GSSP section, western Newfoundland, Canada allows for the identification of the corresponding GSSP level in the Xiaoyangqiao section. The combined data from the Xiaoyangqiao section and the Green Point GSSP section provide a series of events that all can be applied as proxies for identification of the Cambrian–Ordovician boundary horizon outside the GSSP. Based on this, the Xiaoyangqiao section, Dayangcha, is here strongly recommended as a candidate for an Auxiliary Boundary Stratigraphic Section and Point section (ASSP) for the base of the Ordovician System, because it provides one of the best and most complete Cambrian–Ordovician transitions in the world and because the first planktic graptolites are from the Xiaoyangqiao section. © 2019 Elsevier Ireland Ltd Elsevier B.V. and Nanjing Institute of Geology and Palaeontology, CAS
... Overall, the Chinese fauna has been referred to the Late Tremadocian s.l.; nevertheless, biostratigraphical information from the ostracod-bearing units offers a slightly more precise approach to their stratigraphical position. According to Zhang & Erdtmann (2004, fig. 2), the Yehli Formation ranges from the Cambrian-Ordovician boundary to the Early-Late Tremadocian (Aorograptus victoriae Zone, Tr2). ...
... Nevertheless, the Ac. sinensis and H. copiosus Zones (Tr3) of the Fenghsiang Formation were referred to the latest Tremadocian by Zhang & Erdtmann (2004), and more recently, the upper half of the unit was referred to the Early Floian (Zhen et al. 2009). Hence, the ostracod fauna from South China is distinctly younger than that described by Hou (1953a) from North China. ...
Tremadocian–Floian siliciclastic successions in the Argentine Cordillera Oriental are of great interest for the study of early ostracod radiation. Four genera and five species of ostracods have so far been documented in the basin from the Early–Late Tremadocian (Tr2). This contrasts with occurrences from other palaeocontinental areas, where typically only one species is described. Patterns of environmental distribution and ecological approaches of ostracod assemblages were analysed on the basis of richness, Fisher’s alpha diversity, relative abundance and occupancy. Ecological patterns remained stable throughout the studied interval, mostly with one genus notably dominant over the others. At the regional scale, dominant taxa occur at a relatively large number of sites, which display high occupancy. The literature data on carbonate successions from the Baltoscandian basin show a similar pattern, with a single taxon dominant over the others in local assemblages and wide regional distribution of these dominants. This ecological pattern would therefore have persisted at least until the Dapingian, independently of the sedimentary regime. Ostracods were already present along the onshore–offshore gradient during the initial stages of radiation, showing a strong preference for deep subtidal settings during Tr2 and then spreading to shallower environments in Tr3 and to deeper ones in the Floian (Fl2–Fl3). A compilation of ostracod diversity data from several regions shows a remarkable increase during the Darriwilian. Based on the regions studied herein, this rise in diversity is decoupled from the environmental expansion of ostracods, as they were already recorded along the onshore–offshore profile early in their history on both siliciclastic and carbonate shelves. The Argentine Cordillera Oriental could be considered as a cradle of diversity, with an important role in the subsequent radiation of the group.
... The Cambrian-Ordovician boundary interval at Dayangcha section, Jilin, northeastern China (Baishan, Jilin in table 1 of Myrow et al., 2015), has been intensively studied in terms of sedimentology, paleontology, and sequence stratigraphy (Chen et al., 1988, and references therein;Ripperdan et al., 1993;Zhang et al., 1999;Zhang and Erdtmann, 2004). Although Myrow et al. (2015, their table 1) added the section as an unconformity-bearing locality in North China with geological features of "subaerial exposure," the Cambrian-Ordovician succession in the Dayangcha section was in fact described as "rhythmical sequence of lime mudstone and shales" deposited along the outer shelf of the platform (Chen et al., 1988, p. 415). ...
... Correlations between conodont and graptolite zones are facilitated by the conodont-and graptolite-bearing sections of western Newfoundland (e.g., Cooper et al., 2001a,b), southwest Sweden (Löfgren, 1993(Löfgren, , 1996, the eastern Cordillera of Argentina (e.g., Ortega and Albanesi, 2005;Zeballo et al., 2008), and Dayangcha, China (Chen, 1986, Chen et al., 1988Zhang and Erdtmann, 2004). Integrated graptolite and conodont biostratigraphy together with recent studies in stable isotope geochemistry (e.g., Azmy et al., 2014) provide a global correlation framework of high precision for the Tremadocian Stage. ...
... BSEM images illustrate both the chemical compositional differences on the surface layer and the surface morphology of the sample. On the BSEM pictures of Psigraptus jacksoni rickarDs & strait, 1984(zhang & erDtMann, 2004 fig. 11), the carbonized fuselli are marked as dark lines, whereas the rock matrix is brighter because of the dominance of silicon and heavy elements. ...
... BSEM images illustrate both the chemical compositional differences on the surface layer and the surface morphology of the sample. On the BSEM pictures of Psigraptus jacksoni rickarDs & strait, 1984(zhang & erDtMann, 2004 fig. 11), the carbonized fuselli are marked as dark lines, whereas the rock matrix is brighter because of the dominance of silicon and heavy elements. ...
