Acanthomorph Biostratigraphic Succession of the Ediacaran Doushantuo Formation in the East Yangtze Gorges,South China

Large acanthomorphic acritarchs have been found in chert of the Ediacaran Doushantuo Formation at several localities in South China, including the East Yangtze Gorges of Hubei Province,Weng＇an area of Guizhou Province, and elsewhere. However, their potential for biostratigraphic subdivision and correlation of Ediacaran successions is limited by facies control, taphonomic biases,and taxonomic problems. In the Yangtze Gorges, the Doushantuo Formation is generally subdivided into four lithologic members. However, in the Weng＇an area, the Doushantuo Formation comprises just a lower and upper part separated by a mid-Doushantuo erosional surface. In the Yangtze Gorges at the Zhangcunping section, the Doushantuo succession is similar to that at Weng＇an. So far, the correlation between the Yangtze Gorges and Weng＇an area, and elsewhere has been an issue of debate. To resolvethe debate, we selected eight sections in the Yangtze Gorges area and systemically sampled chert nodules of the Doushantuo Formation, focusing in particular on the upper Doushantuo Formation. Our data confirm two different assemblages appearing separately in the second and third members, which are separated by a negative δ13C excursion （EN2）. The lower assemblage is characterized by Tianzhushania and a diverse suite of large acanthomorphic acritarchs. The upper assemblage is distinguished from the lower assemblage, by （1） absence of Tianzhushania; （2） occurrence of abundant,100-150 μm, smooth-walled spherical microfossils; （3） occurrence of highly diverse acanthomorphic acritarchs including species extending from the second member and new forms in this member; （4）occurrence of unnamed new forms of protist; and （5） occurrence of the tubular microfossil Sinocyclocylicus guizhouensis. Since the Tianzhushania-dominated assemblage is not present in Australia, it seems that only the upper acanthomorph assemblage is present and thus the lower Doushantuo acanthomorph assemblage is missing in Australia.

Two Species of Zosterophyllum from South China and Dating of the Xujiachong Formation with a Biostratigraphic Method

ZosterophyUum longa sp. nov. is reported from the Lower Devonian Pingyipu Formation, Jiangyou District, northern Sichuan of China. This new plant has vertically elongate sporangia differing from all known species of Zosterophyllum, demonstrating morphological variations in Zosterophyllophytina. New materials of Zosterophyllum yunnanicum from the Lower Devonian Xujiachong Formation, Qujing District, eastern Yunnan of China show that fertile axes of this species are anisotomous or pseudomonopodial or K-shaped in branching. Sometimes fertile lateral axes are very short and bear an axillary axis at the dividing point. Distinct thickening occurs along the whole margin of a sporangium, with sporangial lobes undeveloped. The evolution of ZosterophyUum is tentatively discussed. A biostratigraphic method of Gerrienne and Streel is introduced and applied to dating of the Lower Devonian Xujiachong Formation, which is considered as of the late Pragian-early Emsian.

Biostratigraphic correlation of the Ordovician black shales in Tarim Basin and its peripheral regions

Ordovician black shales are widely distributed in the Tarim Basin and its peripheral regions,and some of them may serve as potential hydrocarbon source rocks.The present study of the Ordovician graptolite fauna from these shales,together with the yielded conodonts and chitinozoans etc.,permits a refined correlation of the rocks.Based mainly on a new collecting of the graptolites and a study of the faunas in Kalpin and Kuruktag regions,and the successful identification of the new graptolite material from a few drill cores within the basin,we are able to update our knowledge of the Ordovician in the regions,and draw some conclusions:(1) The most widespread distribution of the black shales in the Tarim Basin and its peripheral regions,which correspond to the Nemagraptus gracilis Zone,may be related to a global sea-level rise during this time interval.(2) Black shales of Ordovician occur most frequently and extensively in the Kuruktag(also spelled as Quruq Tagh) region in east-ern Tianshan Mountains,spanning Tremadocian to mid-Katian(D.spiniferus Zone) temporally and extending southeastwards into Manjiaer Depression.The black shales of the D.spiniferus Zone may even extend into the central Tarim Basin.(3) Three different bio-and litho-facies belts(Bachu:carbonate platform and reef belt;Kalpin-Aksu:marginal platform and upper slope belt;Wushi:slope belt) are recognized in the northwestern Tarim Basin.(4) The internationally well-correlated Saergan black shale,which has been considered to possess high potential for hydrocarbon source rock,may possess a restricted distribution in the Kalpin and Aksu areas.

Biostratigraphical significance of the Devonian Sinoleperditiini(Ostracoda)

The Tribe Sinoleperditiini (Ostracoda), which is mainly distributed in South China and its adjacent areas, is a single natural group of the Leperditiidae, characterized by the development of a trailing chevron muscle scar. This tribe is known only from the Devonian and ranges through most of the Devonian. The evolutionary trends within the Sinoleperditiini have been well documented and are exemplified by changes in the trailing chevron muscle scar. The main evolutionary change is a tendency of the trailing chevron muscle scar to extend ventrally through time, as demonstrated by the increasing ratio (th/ah) of the vertical height of the trailing chevron muscle scar (th) to that of the adductor muscle scar (ah). The recent discovery of a sinoleperditiine assemblage (th/ah values available) in the middle-upper Lower Emsian Shanglun Formation allows to propose a sinoleperditiine biostratigraphical sequence for the Devonian. This sequence contains 11 assemblages (th/ah value available for each assemblage), which cover all the 7 Devonian stages and some substages. This sequence is particularly useful for correlating and dating Devonian rocks in the littoral clastic, lagoonal and restricted or semirestricted car-bonate platform facies where these ostracodes are most abundant and other fossils are un-common.

The Tunggurian Stage of the Continental Miocene in China

The Tunggurian Age was nominated in 1984, and the Second National Commission on Stratigraphy of China formally suggested establishing the corresponding chronostratigraphic unit, the Tunggurian Stage, based on the Tunggurian Age in 1999. The name of this stage comes from a lithostratigraphic unit, the Tunggur Formation, and the stratotype section is located at the Tunggur tableland, 15 km southeast of Saihan Gobi Township, Sonid Left Banner, Inner Mongolia. The Tunggurian Age is correlated to the Astaracian of the European land mammal ages, and they share the same definition of the lower boundary at the base of the paleomagnetic Chron C5Bn.1r with an age of 15.0 Ma. In the Tairum Nor section on the southeastern edge of the Tunggur tableland, this boundary is situated within the successive deposits of reddish-brown massive mudstone of the lower part of the Tunggur Formation, with a distance of 7.6 m from the base of the grayish-white sandstones in the middle part of the section. The Tunggurian is approximately correlated to the upper part of the marine Langhian and the marine Serravallian in the International Stratigraphical Chart. The Tunggurian Stage includes two Neogene mammal faunal units, i.e. NMU 6 （MN 6） and NMU 7 （MN 7/8）. The Tairnm Nor fauna from the Talrnm Nor section corresponds to NMU 6, and the Tunggur fauna （senso stricto） from the localities on the northwestern edge of the Tunggur tableland, such as Platybelodon Quarry, Wolf Camp and Moergen, corresponds to NMU 7. Among the Middle Miocene mammalian faunas in China, the Laogou fauna from the Linxia Basin, Gansu, the Quantougou fauna from the Lanzhou Basin, Gansu, the Halamagai fauna from the northern Junggar Basin, Xinjiang, and the Dingjiaergou fauna from Tongxin, Ningxia correspond to NMU 6.

Possible markers of the Jurassic/Cretaceous boundary in the Mediterranean Tethys:A review and state of art

During the last decades,several integrated studies of Tethyan Jurassic/Cretaceous boundary sections from different countries were published with the objective to indicate problems for the selection of biological,chemical or physical markers suitable for identification of the Jurassic/Cretaceous boundary-the only system boundary within the Phanerozoic still not fixed by GSSP.Drawing the boundary between the Jurassic and Cretaceous systems is a matter of global scale discussions.The problem of proposing possible J/K boundary stratotypes results from lack of a global index fossils, global sea level drop,paleogeographic changes causing development of isolated facies areas,as well as from the effect of Late Cimmerian Orogeny.This contribution summarizes and comments data on J/K boundary interval obtained from several important Tethyan sections and shows still existing problems and discrepancies in its determination.

Stratigraphical Time——Correlation and Mass Extinction Event Near Permian——Triassic Boundary in South China

Shaw's method used to correlate 40 sections across the Permo-Triassic boundary in South China is applied in the paper. Two steps are adopted to get an Integral Composite Section (ICS) by synthesizing these data : First , South China is divided into five areas and composite section developed for each area . Then the second step . the Changxing composite section is regarded as a composite standard (CSRS) while the ICS is produced by matching the CSRS with composite sections of the other areas. Three biozones in the Changxingian and two biozones in the Griesbachian can be discerned on the basis of computing Z values in the ICS. These biozones are marked by the Z values which quantitatively represent their time ranges ; therefore , they may increase accuracy of stratigraphic time correlation . The mass extinction at the end of the Permian is an abrupt event that is supported by the relative rate of extinction near the P/T boundary . About 90% of invertebrate species died out by the end of the Permian . The duration of the mass extinction is rather short ,approximately 0.018Ma .

Palynological characteristics of Middle and Upper Jurassic deposits in East Transbaikalye

The author dwells on palynological characteristics of Middle and Upper Jurassic continental deposits in Transbaikalye within the Chita region adjacent to the territory of China. The paper contains descriptions of three sets of spores and pollen taken from Shadoronsk and one set from Undino-Dainsk biostratigraphic horizons. It also provides comparison characteristics of palynocomplexes that belong to Middle and Upper Jurassic deposits in East Transbaikalye with coeval complexes in Siberia and Kazakhstan and provides geological sequence of their formation.

A comprehensive construction of the domain ontology for stratigraphy

Stratigraphic knowledge,the cornerstone of geoscience,needs to be represented by the Knowledge Graph based upon ontology,in order to apply the state-of-the-art big-data techniques.This study aims to comprehensively construct the ontologies for the stratigraphic domain.This has been achieved by a federated,crowd intelligence-based collaboration among domain experts of major stratigraphic subdisciplines.The initial step is to enumerate key terms from authoritative references and incorporate them into the Geoscience Professional Knowledge Graphs(GPKGs)of Deep-time Digital Earth Project.During this process,semantic heterogeneities were meticulously addressed by professional judgement aided by an automatic detection of Homonyms at the GPKGs platform.Afterwards,these terms were further differentiated as either classes or properties and arranged in a hierarchical framework in a top-down process.Consequently,seven ontologies are constructed for major stratigraphic branches,i.e.,Lithostratigraphy,Biostratigraphy,Chronostratigraphy,Chemostratigraphy,Magnetostratigraphy,Cyclostratigraphy and Sequence Stratigraphy.The ontology of Biostratigraphy,among them,is elaborated here,as no biostratigraphic ontology has been attempted before to our knowledge.The constructed biostratigraphic ontology comprises following major root classes:Fossil,Biostratigraphic unit,Biostratigraphic horizon.Altogether,they contribute to the eventual dating and correlating of strata in another root class:Biostratigraphic correlation.In summary,the achievements of this study are probably heretofore the most comprehensive ontologies for the stratigraphic domain.Moreover,a proto model of semantic search engine was conceived to discuss potential application of our work for better querying stratigraphic references,utilizing the semantic liaison of the classes in the constructed ontologies.

End-Permian conodont fauna from Dongpan section:Correlation between the deep-and shallow-water facies

This paper systematically investigated the conodonts from the uppermost Permian to the Lower Triassic at the Dongpan Section, Southern Guangxi, South China, and obtained abundant Late Permian conodonts from the syndepositional limestone lenses of beds 3 and 5-2 at this section. One genus and eight species of conodont P1 element including one new species, Neogondolella dongpanensis sp. nov., have been identified. The feature of conodont fauna indicates that conodonts collected from beds 3 and 5 at the Dongpan Section belong to the Neogondolella yini conodont zone, and correspond to bed 24 at the Meishan Section. Based on these conodont data, we suggest that the Neoalbaillella optima radiolarian zone at the Dongpan Section at least extended to the upper part of the N. yini conodont zone.

Roadian-Wordian(Middle Permian)Conodont Biostratigraphy,Sedimentary Facies and Paleotemperature Evolution at the Shuixiakou Section,Xikou Area,Southeastern Qinling Region,China

Focusing on the Shuixiakou Section(Xikou area,Zhen’an County,Shaanxi Province,southeastern Qinling region,China),the Roadian-Wordian conodonts are investigated.More than 2000 conodont elements including 6 genera and 14 species have been obtained.Based on these materials,the Guadalupian Jinogondolella nankingensis and J.aserrata zones have been recognized.The Roadian-Wordian boundary is tentatively defined by the first occurrence of J.aserrata in the lower part of UnitⅢin the Shuixiakou Formation.The sedimentary succession of Xikou area records similar sea-level changes to those observed in Laibin area(South China).The 40 m-thick bioclastic limestone of UnitⅣin this section can be correlated with the reefs of Bed 114 in Laibin area.A temperature drop indicated byδ18Oapatite values suggests this Wordian interval coincides with a period of glaciation and global regression.