Stratigraphical distribution of the Ordovician graptolite Azygograptus Nicholson & Lapworth in the Central Andean Basin (northwestern Argentina and southern Bolivia)

We analyzed new occurrences of Azygograptus lapworthi from the Cordillera Oriental, Argentina. The bearer sandstones levels, corresponding to the Acoite Formation, are overlying the deposits, in which the Didymograptellus bifidus Biozone (Lower Ordovician, upper Floian, Fl3) was previously recognized, and are overlain by younger pelitic levels yielding Xiphograptus lofuensis (Middle Ordovician, early Dapingian, Dp2). Previous records from the Central Andean Basin are also reviewed in detail and accurately correlated, allowing us to conclude that the Azygograptus lapworthi Biozone corresponds to the Middle Ordovician (lower Dapingian, Dp1). This biostratigraphic framework documents that the transition between the Lower and Middle Ordovician deposits occurs in the uppermost levels of the Acoite Formation in the Argentine Cordillera Oriental. It is additionally integrated with up to date conodont records to establish a high-resolution regional correlation, with equivalent deposits from the Puna of northwestern Argentina and Cordillera Oriental of Bolivia, and to discuss new insights for global correlation.     

Latest Ordovician graptolites from the Mandalay Region,Myanmar

The graptolite fauna of the Mandalay Region, Myanmar, is poorly known. In this paper, 13 species in the genera Avitograptus, Korenograptus, Metabolograptus, Neodiplograptus and Normalograptus are described from the uppermost Ordovician strata of the area. Two of these species, Korenograptus selectus X. Chen n. sp. and Neodiplograptus mandalayensis X. Chen n. sp., are new. On the basis of the graptolite faunas, a biostratigraphic scheme for the uppermost Ordovician (Hirnantian: Metabolograptus extraordinarius Biozone and Metabolograptus? persculptus Biozone?) strata in this area is erected.     

Integrated radiolarian and conodont biostratigraphy of the Middle Permian Gufeng Formation (South China)

Radiolarians are usually abundant in chert sequences and they have thus been widely used for the biostratigraphy of deep-water sediments. However, there are many difficulties in the correlation of radiolarian biostratigraphic schemes with the standard conodont zones. In this study, 21 radiolarian species were extracted from the Gufeng Formation that crops out in the Luojiaba (LJB) section (western Hubei, China), together with 5 co-occurring conodont species. In this way, it is the first time that the Pseudoalbaillella globosa, Follicucullus monacanthus and F. scholasticus radiolarian zones can be directly correlated with the Jinogondolella nankingensis gracilis, J. aserrata and J. postserrata conodont zones. Accordingly, the 3 radiolarians zones are now firmly correlated with the Roadian to middle Capitanian interval (Middle Permian).     

内蒙古乌海大石门奥陶系牙形刺和Histiodella动物群发现的意义

本文描述了内蒙古乌海大石门剖面奥陶系的牙形刺动物群:下克里摩里组主要有Histiodella kristinae,H.holodentata,H.wuhaiensis sp.nov.,Polonodus newfoundlandensis和Paroistodus horridus等,应归属于中奥陶统达瑞威尔阶(Darriwilian)之Histiodella kristinae带,并在同一剖面上与笔石Pterograptus elegans带和Didymograptus murchisoni带下部相当;下克里摩里组顶部产Histiodella kristinae,Baltoplacognathus cf.reclinatus,Periodon aculeatus和Protopanderodus rectus等,所以大石门剖面的Histiodella kristinae带顶部可能已与北欧Pygodus serra带之底部相当;乌拉力克组底部的砾状灰岩透镜体产有牙形刺Pygodus anserinus?,Protopanderodus liripipus,Yangtzeplacognathus protoramosus和Dapsilodus viruensis等,其中Pygodus anserinus?Pa分子(器官种的一组成分子)的口面瘤齿列的瘤齿比较粗糙,与典型的Pygodus anserinus稍有不同,且在牙形刺十分丰富的样品中仅有一枚此种之Pa分子,所以本文尚有疑问地把这层砾状灰岩归入Pygodus anserinus带,同时不能排除把它归入Pygodus serra带顶部Yangtzeplacognathus protoramosus亚带的可能。由于此剖面牙形刺化石与丰富的笔石共生,为牙形刺带与笔石带的精确对比提供了直接证据。Histiodella动物群在此剖面的发现,不仅具有十分重要的地层意义,而且具有明显的岩相古地理意义。本文详细描述了新种Histiodella wuhaiensis并讨论了Histiodella属5个种之区别。     

新疆乌什下寒武统肖尔布拉克组软舌螺化石

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。     

New graptolite,chitinozoan and acritarch records from the Pascha-Incamayo area,Cordillera Oriental,Argentina

A new fossil assemblage bearing graptolites, chitinozoans and acritarchs is analyzed based on material collected in the Pascha-Incamayo area, Salta Province, NW Argentina. The occurrence of Hunnegraptus copiosus (Lindholm, 1991), associated with specimens of the genus Tetragraptus (Salter, 1863), is highly relevant to improve the age assignment and correlate the fossil-bearing levels previously assigned to the Devendeus Formation. Different stages in the development of the index species of the Upper Tremadocian H. copiosus Biozone are described and illustrated. The precise stratigraphic ranges of the associated chitinozoans and acritarchs are discussed, according to the biostratigraphic analysis, and the stratigraphic relationships for the studied section are considered.     

An Early Ordovician Trilobite assemblage from the Lashkarak Formation, Damghan area, northern Iran

A low diversity Lower Ordovician trilobite assemblage is described from the middle part of the Lashkarak Formation at Simeh-Kuh, northwest of Damghan, northern Iran. Co-occurrence with conodonts of the lowermost Paroistodusproteus Biozone suggests an uppermost Tremadocian age. This assemblage includes four taxa, including one new genus and two new species, Damghanampyxginteri nov. gen. nov. sp. and Asaphellusfecundus nov. sp. The third diagnosable species from the formation is Taihungshaniamiqueli (Bergeron, 1894) which has previously been reported from southern France and the Turkish Taurides, suggesting north Gondwanan faunal affinities.     

The Lerhamn drill core and its bearing for the graptolite biostratigraphy of the Ordovician Tøyen Shale in Scania,southern Sweden

Maletz, J. & Ahlberg, P. 2011: The Lerhamn drill core and its bearing for the graptolite biostratigraphy of the Ordovician Tøyen Shale in Scania, southern Sweden. Lethaia, Vol. 44, pp. 350–368. A drill core through the Lower Ordovician Tøyen Shale Formation at Lerhamn, NW Scania, southern Sweden, provides important new information for the precise biostratigraphic resolution of the Floian to lower Darriwilian time interval in southern Scandinavia. The Hunnegraptus copiosus, Tetragraptus phyllograptoides, Cymatograptus protobalticus (new), Baltograptus vacillans (new), Baltograptus sp. cf. Baltograptus deflexus (new), Baltograptus minutus (new), Isograptus victoriae, Undulograptus austrodentatus (Arienigraptus zhejiangensis and Undulograptus sinicus Subzones) and the (?)Corymbograptus retroflexus (new) biozones are differentiated in the core and their correlation in Scania is discussed. The Lerhamn drill core provides the most detailed graptolite record of the Floian Stage in Scandinavia. The interval is dominated by a number of species of the genus Baltograptus, endemic to the Atlantic Faunal realm and highly useful for regional biostratigraphic correlation. The biostratigraphic framework is based on endemic and pandemic faunal elements. The mixture of both elements in the drill core allows a more precise inter‐continental correlation of Lower to Middle Ordovician graptolite faunas and may – in the future – provide information as to the climatic history of regions dominated by Baltograptus faunas in the Floian. The (?)C. retroflexus Biozone is based on species originally described from Bohemia, but the record of the zone in the Lerhamn drill core indicates a wider distribution of its fauna. □Biostratigraphy, graptolites, Ordovician, Scania, Sweden.     

Stratigraphic distribution of selected acritarchs in the Ordovician subsurface,Canning Basin,Western Australia

Palynological investigation of 80 core samples from four boreholes, drilled through the Lower to Middle Ordovician marine sections of the central-northeastern Canning Basin, northwestern Australia, reveals diverse acritarch associations including a number of stratigraphically significant species. The stratigraphic succession studied, embracing the Willara Formation and conformably overlying Goldwyer Formation, has been independently dated as early Arenig to Llanvirn by conodont faunas (Oepikodus communis through Phragmodus-Plectodina zonal interval). Nine morphologically distinctive acritarch species have relatively narrow vertical ranges within the study interval and likely constitute serviceable palynostratigraphic indices for the Ordovician in and possibly beyond the Western Australian study area. Three new species, Comasphaeridium setaricum, Polyancistrodorus kunzeanensis, and Stelomorpha calix, are established; and one new combination, Baltisphaeridium variocavatum (Playford and Martin, 1984), is proposed. Other stratigraphically significant species include Petaloferidium comptum Playford and Martin, 1984 and Peteinosphaeridium sp. cf. P. exornatum Tongiorgi et al., 1995; together with Dorsennidium symmetricum (Lu, 1987) Sarjeant and Stancliffe, 1994, Peteinosphaeridium coronula Yin et al., 1998, and Striatotheca rarirrugulata (Cramer et al., 1974) Eisenack et al., 1976, which are found for the first time in Australia. The vertical distribution, and hence the stratigraphic utility, of each of the above species is documented through the studied sections.     

High‐resolution conodont biostratigraphy from the Darriwilian Stage (Middle Ordovician) of the Argentine Precordillera and biodiversity analyses: a CONOP9 approach

Ordovician conodonts have been extensively documented in the Argentine Precordillera, providing a robust database for a diverse set of palaeontological studies. Despite the numerous studies, the published taxonomy and stratigraphical ranges, data remain contradictory for particular time intervals. Data from a new conodont collection from the Gualcamayo Formation exposed at the Cerro La Chilca section, and new information on the occurrence and ranges of species from the Las Chacritas and Las Aguaditas sections are presented herein. We used a computer‐assisted numerical sequencing program (CONOP9) to construct a composite stratigraphical range chart from data of 57 conodont species in four sections from the Argentine Precordillera. The identified zones of Lenodus variabilis, Yangtzeplacognathus crassus, Eoplacognathus pseudoplanus and Eoplacognathus suecicus allowed us to verify and adjust the biostratigraphical scheme for the Darriwilian of the Central Precordillera. Additionally, species of the genera Histiodella, namely Histiodella sinuosa, Histiodella holodentata, Histiodella kristinae and Histiodella bellburnenisis, enable a reasonable correlation between the Histiodella‐based zonation and the Baltoscandian zonation. Conodont diversity is evaluated using conventional measures (total diversity and normalized diversity) and an interval‐free approach with CONOP9 software. Our data show a positive pattern in conodont diversification, increasing rapidly through the L. variabilis to the Y. crassus zones and reaching a peak in the E. pseudoplanus Zone. When analysing diversity fluctuations with respect to the environmental changes within the depositional basin, migrations in and out of the basin related to local sea level fluctuations appear to be an important process driving the conodont diversity pattern in the Precordillera.     

Discovery of Anticostia uniformis from the Xiazhen Formation at Zhuzhai,South China and its stratigraphic implication

The Xiazhen Formation is an Upper Ordovician lithostratigraphic unit in the Jiangshan-Changshan-Yushan (JCY) area, which contains series of Late Ordovician reef successions. The reef successions of the Xiazhen Formation at Zhuzhai are critical for evaluation of the Late Ordovician marine diversity and palaeoecology. However, their age has long been uncertain and generally is regarded as of upper Katian, based on the occurrences of shelly fossils and correlation with the stratigraphic equivalent Changwu Formation. The newly discovered graptolite species Anticostia uniformis, in the Xiazhen Formation, together with the combined evidence of brachiopods and sedimentology, indicates an age range for the graptolite locality from the Dicellograptus complanatus Biozone to the Diceratograptus mirus Subzone of late Katian, but the graptolites do not rule out the possibility that it is Hirnantian.     

Proposition d’une nouvelle biozonation par ammonites de l’Albien du Bassin andin (Pérou)

The study of the ammonite fauna of the Albian formations allows a major revision of its biostratigraphic frame in northern and central Peru. A carving in ammonite biozones is proposed for the Inca, Chulec and Pariatambo Formations and the Pulluicana group. The Lower Albian is represented by the Nicholsoni Biozone (subdivided into the umbilicostatus, and nicholsoni biohorizons, followed by an interval subzone) and by the Raimondii Biozone (carved in three subzones: Haasi, Raimondii – itself subdivided into the ebrayi and alternum biohorizons – and Mathewsi, including the pseudolyelli biohorizon). The Middle Albian is characterised by the Carbonarium Biozone, carved in the Ulrichi and Carbonarium Subzones. The base of Upper Albian is represented by the Cristatum Subzone.     

Lower Emsian biostratigraphy and event stratigraphy of Ha Giang Province,northern Vietnam

A new species of rugose coral, Sanidophyllum dubium n. sp., and the typical Emsian (Early Devonian) rugose coral Xystriphylloides nobilis are described from the Mia Le Formation in northern Vietnam. The lower Emsian index conodonts ranging from the Polygnathus excavatus zone to the P. nothoperbonus zone are illustrated. The biostratigraphic correlation between northern Vietnam and South China shows that the Mia Le Formation in northern Vietnam is early Emsian in age, and its upper part can be correlated with the lower part of the Shizhou Member of the Yukiang Formation in Liujing, Guangxi and its equivalents in South China. Based on the study of the lower Emsian biostratigraphic sequence, the disappearance of Xystriphylloides nobilis fauna in the overlying bed of the uppermost Mia Le Formation and the extinction of the “tonkinensis fauna” (sensu lato) in the interval between the basal Si Phai Formation and the uppermost Mia Le Formation demonstrate the influence of the Yujiang Event in northern Vietnam.     

Famennian (Late Devonian) ammonoids from the Ouarourout section (Saoura Valley,Algeria)

In North Africa, the ammonoids constitute an important part of the Devonian marine macro-invertebrates. New material has been recently collected in the ‘Argiles de Marhouma’ Formation from several sections located near Béni-Abbès in the Saoura Valley (Ougarta Mountains, Algerian Sahara). Red nodular limestones (i.e., ‘griotte’ facies) characterize this formation rich in ammonoids. The assemblages from the Ouarourout section are composed of Goniatitida and Clymeniida constituting 30 species and 19 genera belonging to 11 families, with Cyrtoclymenia, Erfoudites, Kosmoclymenia, Planitornoceras, Platyclymenia, and Prionoceras, as the most abundant genera. The taxonomic comparison and the biostratigraphic correlations are made by considering the assemblages recorded in the Anti-Atlas of Morocco, which are very close to those observed in Algeria. In the Ouarourout area, the ‘Argiles de Marhouma’ Formation contains middle and late Famennian ammonoid assemblages and three biostratigraphic intervals can be identified: Planitornoceras, Platyclymenia and Medioclymenia.     

Dispersal of Pleistocene Equus (Family Equidae) into South America and Calibration of GABI 3 Based on Evidence from Tarija,Bolivia

The dispersal of Equus into South America during the Great American Biotic Interchange (GABI) represented a major event for Pleistocene land-mammal age chronology on that continent. It has been argued that this dispersal occurred during the late Pleistocene, ∼0.125 Ma, and it defines the base of the Lujanian South American Land Mammal Age (SALMA). In this scenario, Equus dispersed during the fourth and latest recognized phase of the interchange, i.e., GABI 4. Although Equus was widely distributed in South America during the Pleistocene, only a few localities are calibrated by independent chronostratigraphic data. In this paper, new biostratigraphic evidence documents that Equus occurs from 15 superposed faunal horizons or zones throughout the Tolomosa Formation at Tarija, Bolivia. This biostratigraphic sequence is independently calibrated to occur between ∼0.99 to <0.76 Ma during the middle Pleistocene Ensenadan SALMA and coincident with GABI 3, not GABI 4. Tarija remains the only well calibrated Ensenadan locality at which Equus is found. The new biostratigraphic data presented here are unambiguous and document the earlier (pre-Lujanian) occurrence of this genus in South America. The hypothesized dispersal of the genus Equus into South America at ∼0.125 Ma is no longer supportable in light of the new biostratigraphic evidence presented here. The new data from Tarija thus have continent-wide implications for the origins and biogeography of Equus in South America as well as the calibration of GABI 3.     

Age constraints of the Hungshihyen Formation (Early to Middle Ordovician) on the western margin of the Yangtze Platform,South China: New insights from chitinozoans

The Hungshihyen Formation represents the Lower to Middle Ordovician near-shore siliciclastic deposits on the western margin of the Yangtze Platform, South China. However, its age is still debated, largely because of insufficient studies. Here we documented the Bursachitina maotaiensis–B. qianbeiensis chitinozoan assemblage from the lower part of the Hungshihyen Formation at Songliang, Qiaojia County, eastern Yunnan Province. This assemblage is remarkably similar to an assemblage that roughly correlates to the middle part of the Corymobograptus deflexus graptolite Biozone in northern Guizhou Province, indicating that the Hungshihyen Formation at Songliang is probably of late Floian age and may extend into the early Dapingian. Additionally, a revision on the chitinozoans previously documented from the strata assigned to the same formation in the Wuding area was made according to the latest classification. The revision allows the recognition of the Euconochitina symmetrica–Eremochitina brevis assemblage, and therefore suggests a late Tremadocian age for this interval based on regional and global chitinozoan biostratigraphic correlations. Considering also its lithologic succession, we argue that the chitinozoan-bearing strata in the Wuding area previously assigned to the Hungshihyen Formation correspond most likely to the uppermost part of the underlying Tangchi Formation or the lowermost part of the Hungshihyen Formation. The base of the Hungshihyen Formation appears therefore to be diachronous in eastern Yunnan Province.     

Paleogene ostracodes from the Dawenkou Basin,East China and their biostratigraphic significance for the age of mineral resources

The Dawenkou Basin is a Cenozoic terrestrial fault basin in Shandong Province, East China, containing abundant mineral resources, especially gypsum. Recently a borehole was drilled in this basin unearthing the upper and middle members of the Dawenkou Formation. From the upper member, well-preserved ostracodes were discovered, which are entirely non-marine taxa including species of Eucypris, Caspiolla, Candona and Candoniella. Based on the new material, a new species Candona dawenkouensis n. sp. was erected. The ostracode assemblage biostratigraphically indicates an age of middle Eocene to Oligocene of the upper member of the Dawenkou Formation and the strata bearing mineral resources (mainly gypsum) of the middle member of the Dawenkou Formation is likely early Eocene.     

Pelecyogyra (Mollusca) from the Early Ordovician of the Montagne Noire,France

A new occurrence of the onychochilid mollusc Pelecyogyra is reported from the late Floian Landeyran Formation (Apatokephalus incisus Biozone) in the Montagne Noire, southern France, where it is associated with the two tergomyans Carcassonnella courtessolei and Thoralispira laevis, and a mollusc indet. With a low cap-shaped shell. The Montagne Noire specimens compare morphologically with Pelecyogyra fezouataensis from the late Tremadocian Fezouata Formation (Araneograptus murrayi Biozone) in Morocco and are tentatively referred to this species. Each occurrence of Pelecyogyra is from one or two localities only, but separated in time. They differ further in the deeper facies, association with Carcassonnella and Thoralispira, and non-gregarious occurrence in Montagne Noire compared to the shallower facies, lack of other molluscs and gregarious occurrence in the Fezouata Formation. In the Lower Ordovician, Pelecyogyra, Carcassonnella courtessolei, the rare C. vizcainoi and Thoralispira laevis are taxa that occur only in Montage Noire and the Anti-Atlas, while Lesueurilla prima also occurs in the Prague basin of the Czech Republic. Contrary to other faunal elements, like echinoderms and trilobites, these genera seem to have a wide environmental tolerance and are long ranging taxa. The main occurrence of the three key taxa Carcassonnella, Thoralispira and Lesueurilla in the Montagne Noire is in the lower part of the La Maurerie Formation (Taihungshania miqueli acme Zone), while the same taxa appear just slightly later in Morocco (?Cymatograptus protobalticus Biozone). Migration to the Anti-Atlas during the early Floian seems to have been possible during a period of general faunal exchange. Pelecyogyra may either have migrated from the Anti-Atlas to Montagne Noire during the same interval or possibly during the late Floian as indicated by shared faunal elements between these two regions at that time.     

Proposal for adoption of the base of the Undulograptus austrodentatus Biozone as a global Ordovician stage and series boundary level

The base of the Undulograptus austrodentatus Biozone appears to be a synchronous event that is widely recognizable within graptolitic facies around the world. It occurs within an interval in which graptolite species ranges are now well known and in which there is a rapid turnover in the composition of graptolite faunas. This turnover reflects the rapid evolutionary radiation of the Diplograptacea simultaneously with the appearance of several distinctive pseudisograptid and glossograptid species. These events provide the basis for the recognition of two thin but widely applicable subzones; a lower Arienigraptus zhejiangensis Subzone and an upper U. sinicus Subzone. The occurrence of the lower boundary of the U. austrodentatus Biozone within a succession of first appearances also permits accurate and reliable identification of the boundary as well as assessment of stratigraphic completeness across the boundary interval in correlated sections. Diverse graptolite faunas of late Yapeenian and early Darriwilian age occur in association with the Histiodella altifrons Biozone of the North American midcontinent conodont zonation and the Paroistodus originalis and Microzarkodina parva biozones of the North Atlantic conodont zonation. They also occur in association with the shelly-fossil zonations developed for several different continents. These features of the base of the U. austrodentatus Biozone make it a suitable level for use as the boundary level for a global stage. Its stratigraphic position within the Ordovician System relative to other likely global stages as well as its coincidence with one of the major events in graptolite evolutionary history suggest that this level also may be a suitable level for the base of a global Middle Ordovician Series.Ordovician System, Ordovician stages, graptolite zonation, chronostratigraphy, international correlation. Charles E. Mitchell and Jörg Maletz, Department of Geology, State University of New York at Buffalo, Buffalo, New York 14260-1550, USA; 13th July, 1994; revised 22nd May, 1995.     

Age of the Silurian Wuxiahe Formation in Langao,Northwest China: New conodont data

A recent study of conodonts from the Wuxiahe Formation (lower to middle part) in the Ziyang-Langao region suggested its age of middle Telychian (Llandovery) to lower Sheinwoodian (Wenlock), contradicted by subsequent graptolite studies indicating an age of late Telychian for the same interval. New samples from the Qiaoxi section for conodonts to re-access the age of the Wuxiahe Formation collected in this study show that the lower to middle part of the formation belongs to the Pterospathodus amorphognathoides amorphognathoides Biozone, suggesting the age of late Telychian; thus, the Llandovery–Wenlock boundary in the section is most probably higher than previously estimated, but its precise position is not determined since the identification of the Wenlock graptolite Cyrtograptus cf. lundgreni in the section is to be further confirmed. Based on the conodont faunas recognized in the Qiaoxi and Tianwancun sections, the base of the Wuxiahe Formation in the Ziyang-Langao region is diachronous, i.e., not higher than the upper Telychian Pterospathodus amorphognathoides amorphognathoides Biozone at Qiaoxi, but not lower than the lower Sheinwoodian Kockelella ranuliformis Biozone at the Tianwancun setion.