A Middle–Upper Devonian Boundary Section in the Open Platform,Platform Margin Facies of Guilin, South China

Abstract: The Caiziyan Middle and Upper Devonian boundary section is located approximately 30 km northeast of Guilin. It hosts relatively abundant benthic and common–rare pelagic fossils, including brachiopods, corals, tentaculites, and conodonts, which may serve as a better suitable section for pelagic and neritic stratigraphic correlation. In this section, 10 “standard” conodont zones are recognized across the Givetian–Frasnian boundary, including, in descending order, the Lower hassi Zone, punctata Zone, transitans Zone, the Upper falsiovalis Zone, the Lower falsiovalis Zone, disparilis Zone, the Upper hermanni–cristatus Zone, the Lower hermanni–cristatus Zone, the Upper varcus Zone, and the Middle varcus Zone, all of which are defined by the first occurrence of their defining conodont species. The Middle–Upper Devonian (Givetian–Frasnian) boundary is defined by the first occurrence of Ancyrodella pristina in accordance with the Global Stratotype Section and Point (GSSP), which is assigned at 6.2m above the base of bed 19 in the Caiziyan section.     

A Middle-Upper Devonian Boundary Section in the Open Platform,Platform Margin Facies of Guilin,South China

The Caiziyan Middle and Upper Devonian boundary section is located approximately 30 km northeast of Guilin.It hosts relatively abundant benthic and common-rare pelagic fossils,including brachiopods,corals,tentaculites,and conodonts,which may serve as a better suitable section for pelagic and neritic stratigraphic correlation.In this section,10"standard"conodont zones are recognized across the Givetian-Frasnian boundary,including,in descending order,the Lower hassi Zone,punctata Zone,transitans Zone,the U...     

Conodont Biostratigraphy and Age Determination of the Lower–Middle Triassic Boundary in South Guizhou Province, China

The demarcation of the Lower–Middle Triassic boundary is a disputed problem in global stratigraphic research. Lower–Middle Triassic strata of different types, from platform to basin facies, are well developed in Southwest China. This is favorable for the study of the Olenekian–Anisian boundary and establishing a stratotype for the Qingyan Stage. Based on research at the Ganheqiao section in Wangmo county and the Qingyan section in Guiyang city, Guizhou province, six conodont zones have been recognized, which can be correlated with those in other regions, in ascending order as follows: 1, Neospathodus cristagalli Interval-Zone; 2, Neospathodus pakistanensis Interval-Zone; 3, Neospathodus waageni Interval-Zone; 4, Neospathodus homeri-N. triangularis Assemblage-Zone; 5, Chiosella timorensis Interval-Zone; and 6, Neogongdolella regalis Range-Zone. An evolutionary series of the Early–Middle Triassic conodont genera Neospathodus-Chiosella-Neogongdolella discovered in the Ganheqiao and Qingyan sections has an intermediate type named Neospathodus qingyanensis that appears between Neospathodus homeri and Chiosella timorensis in the upper part of the Neospathodus homeri-N. triangularis Zone, showing an excellent evolutionary relationship of conodonts near the Lower–Middle Triassic boundary. The Lower–Middle Triassic boundary is located at 1.5 m below the top of the Ziyun Formation, where Chiosella timorensis Zone first appears in the Qingyan section, whereas this boundary is located 0.5 m below the top of the Ziyun Formation, where Chiosella timorensis Zone first appears in the Ganheqiao section. There exists one nearly 6-m thick vitric tuff bed at the bottom of the Xinyuan Formation in the Ganheqiao section, which is usually regarded as a lithologic symbol of the Lower–Middle Triassic boundary in South China. Based on the analysis of high-precision and high-sensitivity Secondary Ion Mass Spectrum data, the zircon age of this tuff has a weighted mean 206Pb/238U age of 239.0±2.9Ma (2s), which is a directly measured zircon U-Pb age of the Lower–Middle Triassic boundary. The Ganheqiao section in Wangmo county can therefore provide an excellent section through the Lower–Middle Triassic because it is continuous, the evolution of the conodonts is distinctive and the regionally stable distributed vitric tuff near the Lower–Middle Triassic boundary can be regarded as a regional key isochronal layer. This section can be regarded not only as a standard section for the establishment of the Qingyan Stage in China, but also as a reference section for the GSSP of the Lower–Middle Triassic boundary.     

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.     

Choice of conodont Idiognathodus simulator （sensu stricto） as the event marker for the base of the global Gzhelian Stage （Upper Pennsylvanian Series,Carboniferous System）

We propose that the level at which the conodont species Idiognathodus simulator （Ellison 1941） （sensu stricto） first appears be selected to mark the base of the Gzhelian Stage, because we believe that this is the optimal level by which this boundary can be correlated. This taxon has a short range and a wide distribution, as shown by correlation of glacial-eustatic cyclothems across the Kasimovian-Gzhelian boundary interval among Midcontinent North America and the Moscow and Donets basins of eastern Europe, based on scale of the cyclothems along with several aspects of biostrati- graphy. Outside of these areas, I. simulator （sensu stricto） is known also from other parts of the U.S., and is reported from the southern Urals and south-central China in its expected position between other widespread taxa. Its first appearance is consistent with the current ammonoid placement of the boundary （first appearance of Shumardites cuyleri）, and it is also compatible with certain aspects of the distribution of Eurasian fusulinid faunas （e.g., lectotype ofRauserites rossicus）.     

Environment and Age of the Upper Devonian‒Carboniferous Zhulumute and Hongguleleng Formations, Junggar Basin, NW China: Ichnological and Palynological Aspects

Two Upper Devonian to Lower Carboniferous sections, namely the Bulongguoer and Haer(Gennaren area) in the Junggar Basin, Central Asian Orogenic Belt, in northwestern China were examined with regard to ichnology and palynology. The deposits of the Hongguleleng Formation and Namu Member of the Heishantou Formation, respectively, are mostly unbioturbated or poorly bioturbated, with poorly diversified trace fossils, which indicate unfavourable conditions for the burrowing benthic community during the Late Devonian and Early Carboniferous. The main factor governing the growth of the bioturbating population was the rapid sedimentation of fine-grained, volcanic material documented as tempestites, which buried the benthic fauna. In the Bulongguoer section, the presence of miospores Teichertospora torquata and Grandispora gracilis enabled identification of the broad Teichertospora torquata–Grandispora gracilis Miospore Zone from the transitional Frasnian/Famennian interval. More accurate identification of palynostratigraphical levels(DE and CZ Miospore zones) is only tentative. On the basis of palynofacies analysis, samples from the lower Bulongguoer section indicate deposition in more proximal conditions, whereas samples from the top of the section indicate deposition in a more distal environment. In the Haer section, only a general biostratigraphic indication for the Tournaisian was possible, owing to poor preservation of organic matter.     

On the Yangtzeconus Priscus-Archaeospira Ornata Assemblage (Mollusca) of the Earliest Cambrian of China

Yangtzeconus priscus-Archaeospira ornata, an important earliest Cambrian benthonic Assemblage of the Yangtze micromolluscan fauna, occurs mainly in the Lower Cambrian Zhongyicun and Dahai Members of the Yuhucun Formation in E Yunnan, the Tianzhushan Member （=Huangshandong Member） of the Dengying Formation in W Hubei and the Maidiping Member of the Hungchunping Formation in C Sichuan, China. About 90% of the genera of this Assemblage are unknown from the Nemakit-Daldynian and Tommotian molluscan Assemblages of the Siberian Platform, Russia. About 90% of the Siberian molluscan genera do not occur in the Zhongyicun and Dahai Members in the Meishucun section and in the corresponding beds of the Yangtze Platform, because the Tommotian molluscan Assemblage is characterizedly abundant archaeocyathids. It is clearly indicated that the Yangtze and Siberian molluscan Assemblages represent different bio- and lithofacies and ages. The age of the pre-trilobitic Yangtzeconus priscus-Archaeospira ornata Assemblage is older than that of the Nemakit-Daldynian and Tommotian molluscan Assemblages and referable to the Earliest Cambrian. Two new genera Mcnamaraconus and Zhangwentangoconus are herein proposed.     

Characteristics of Albaillella （ Albaillellarian ,Radiolarian） Fauna from Guadalupian to Lopingian Series in Permian, South China

On the basis of establishment of radiolarian biostratigraphy and conodont biostratigraphy,a radiolarian Albaillella fauna in the transitional environment from Guadalupian to Lopingian Series in Permian was found at a pelagic chert section in southeast Guangxi, South China. Radiolarian Albaillella is one of the most sensitive biology to the transitional environment. The Albaillella fauna shows an ecological evolutionary process from Guadalupian to Lopingian: declined stage-recovery stage-flourishing stage. The study of characteristics of the Albaillella fauna in the transitional environment may provide more information, not only for the subdivision and correlation of a high-resolution biostratigraphy, but also for influence of radiolarian Albaillella fauna on the pre-Lopingian mass extinction.     

Middle and Late Carboniferous Tetracoral Assemblages and Biogeography of China

China is rich in Middle and Carboniferous fossil corals. The coral faunas in different regions have varying characteristics and can be divided into distinct assemblages. The coral fauna in South China is dominated by the order Caninida and contains numerous endemic elements; that in North China has a lot of Middle Carboniferous corals which are monotonous in species, with Late Carboniferous solitary corals being predominant. The coral fauna in Junggar mainly contains large bi-zoned solitary caninids, while that in southern Khingan is similar to that in South China due to the presence of abundant tri-zoned compound corals. In northern Tibet the coral fauna is also similar to that in South China, but in southern Tibet it is of a cold-water type. Therefore, the Middle and Late Carboniferous coral geography of China can be divided into the Tethys, Boreal and Gondwana Realms.     

Biostratigraphy,Microfacies, Sedimentary Environments and Sequence Stratigraphy of the Late Devonian–Carboniferous Deposits at the Anarak Section,Central Iran

The Late Devonian–early Carboniferous deposits of the Anarak section in northeastern Isfahan, Central Iran, evaluated based on conodont biostratigraphy, sedimentary environment and sequence stratigraphy. According to the field observations, five lithological units were identified. Investigating the conodont fauna of the Late Devonian–Carboniferous(Mississippian–Pennsylvanian) deposits of Bahram, Shishtu, and Qaleh(Sardar 1) formations in Anarak section led to the identification of 67 species of ...     

广西象州中坪马鞍山剖面上泥盆统弗拉斯阶/法门阶(F/F)界线的研究

笔者在广西象州中坪马鞍山剖面上泥盆统“融县组”中部,首次发现了地层连续、岩性均一、牙形石带齐全的弗拉斯阶/法门阶界线层。这一界线层完全符合国际泥盆纪地层分会(SDS 1983)作出的关于划分弗拉斯阶/法门阶界线条件的决议。并与被誉为盆地相最佳剖面的西德Schmidt剖面(SDS Newsl.1986,no.1,Doc.C)的牙形石序列基本一致。无论是从岩石的均一性或是牙形石生物的连续性上,马鞍山剖面完全可与西德Schmidt剖面媲美,它是目前国内研究弗拉斯阶/法门阶界线的理想剖面之一。本文除了对这一界线进     

湘中佘田桥剖面上泥盆统弗拉斯阶地层研究新进展

湘中佘田桥剖面的佘田桥阶大致与弗拉斯阶范围一致 ,其下为吉维阶泥质灰岩 ,含腕足类 Emanuella tak-wanensis等及竹节石 Viriatellina kienelensis等。佘田桥阶自下而上分别为榴江组、蒸水河组、老江冲组。榴江组主要是紫红色粉砂质泥岩 /粉砂岩互层、底部为黑色薄层硅质岩。蒸水河组下部以灰黑色及暗灰色钙质泥页岩为主 ,含介形虫 Bertillonella erecta、B.cicatricosa?、Franklinella calcarata、Entomozoe(N ehdentomis) tenera及菊石 Meso-beloceras?sp.;上部泥质灰岩、似瘤状灰岩、粉砂质泥岩含牙形石 Palmatolepis cf.semichatovae、大型菊石 Mantico-ceras sp.及介形虫 Entomozoe(N ehdentomis) pseudorichterina。老江冲组以泥页岩为主 ,顶部附近则出现一些泥质灰岩、似瘤状泥灰岩层 ,产丰富的小嘴贝类、无洞贝类及弓石燕类等腕足动物 ,少量海绵 (?)及珊瑚等。佘田桥阶的顶界与弗拉斯阶的顶界一致 ,即以无洞贝类和大量四射珊瑚的绝灭为标志 ,而 Yannanellina腕足动物群的出现开始于锡矿山阶 (或法门阶 )。综合各类化石资料 ,佘田桥剖面的榴江组大致相当于牙形石 falsiovalis带— punctata带 ,蒸水河组相当于 L ower hassi带— L ower rhenana带 ,老江冲组相当于 U pper rhenana带— linguiform     

广西六景泥盆系弗拉斯阶-法门阶界线层牙形石生物地层及碳同位素组成

广西六景泥盆系剖面是中国泥盆系标准剖面之一,通过对其弗拉斯阶-法门阶(F-F)界线附近地层进行详细的牙形石生物地层研究,自下而上识别出3个牙形石带:晚rhenana带、linguiformis带和triangularis带。F-F界线位于融县组下部(第7号层与第8号层之间),在谷闭组顶界之上3.32,m处。碳同位素的分析结果表明,F-F之交δ13C具有显著正偏移,增幅为2.0‰,与湖南老江冲、广西垌村和杨堤以及欧洲、美洲、非洲和澳洲等地的F-F界线附近的碳同位素记录一致,且具有相近的变化幅度。δ13C正异常与F-F界线上的生物灭绝有关,由于食微生物的高等生物灭绝,微生物大量繁盛,诱导海水缺氧,导致海洋有机碳埋藏速率增加,从而形成δ13C的正偏。F-F界线层发育一套以碎屑灰岩为特色的事件沉积,该事件沉积在广西乃至全球具有等时性,可能与小行星碰撞地球引起的全球性海啸有关。     

广西全州地区晚泥盆世牙形石和腕足类生物地层

广西东北部泥盆系发育良好,化石丰富,对研究中国华南地区泥盆纪生物地层具有重要意义。对广西全州地区东山剖面上泥盆统佘田桥组、锡矿山组和孟公坳组进行了系统的化石采集及室内分析,共获得104枚牙形石化石和34件腕足类化石。经鉴定,牙形石共21属19种,腕足类化石共6属9种。根据化石种属在东山剖面上的分布,自下而上可划分出8个牙形石带:Icriodus brecis带,Schmidtognathus hermanni-Polygnathus cristatus带,Schmidtognatus wittekindtii带,Palmatolepis linguiformis带,Palmatolepis triangularis带,Palmatolepis rhomboidea带,Icriodus cornutus带和Palmatolepis gracilis manca-Rhodalepis polylophodontiformis带,指示研究区内佘田桥组、锡矿山组、孟公坳组分别对应国际年代地层单位的弗拉斯阶上部、法门阶下部和法门阶中上部,并通过Palmatolepis triangularis的首现确立了该地区弗拉斯阶和法门阶(F-F)的界线;在东山剖面共划分出2个腕足类组合带:弓石燕(Cyrtospirifer)组合带和云南贝(Yunnanella)-帐幕石燕(Tenticosififer)组合带,它们分别与东山剖面中牙形石Palmatolepis falsiovalis-Palmatolepis linguiformis带、Palmatolepis rhomboidea-Palmatolepis marginifera带对应。     

新疆巴楚地区的“Icriodus de formatus”（牙形刺）与巴楚组和东河塘组的时代

新疆巴楚小海子剖面发现的牙形刺被有关作者鉴定为Icriodus de formatus Han，并将弗拉斯阶-法门阶界线置于巴楚组中段底部，认为东河塘组的时代为弗拉斯期或更老。但巴楚小海子剖面的牙形刺不是Icriodus de formatus，泥盆系-石炭系的界线应划在巴楚组中段下部之内，东河塘组的时代很可能是法门期的。     

Frasnian–Famennian crisis in the Malaguide Complex (Betic Cordillera,Spain)

Devonian sediments of the Malaguide Complex potentially could include the Frasnian–Famennian boundary, one of the five greatest Phanerozoic biotic crises. Conodont biofacies and microfacies of carbonate clasts from a pebbly mudstone underlying Tournaisian radiolarites allows identification, for the first time in the Malaguide Complex, of Devonian shallow marine environments laterally grading to deeper realms. The clasts yielded Frasnian conodont associations of the falsiovalis to rhenana biozones, with six biofacies that reveal different environmental conditions in their source areas. Source sediments were dismantled and redeposited within the pebbly mudstone, whose origin is tentatively related to one of the events that are associated worldwide with the Frasnian–Famennian crisis. The latter is recorded, in two equivalent Malaguide pelagic successions, by stratigraphic discontinuities, and it was, probably, tectonically and/or eustatically controlled, as in other Alpine‐Mediterranean Paleotethyan margins.     

Palynological and bulk geochemical constraints on the paleoceanographic conditions across the Frasnian–Famennian boundary,New Albany Shale,Indiana

A down-core record of stable isotope and geochemical results is integrated with palynofacies (kerogen) data from the New Albany Shale (Indiana) to reconstruct environmental changes that occurred across the Frasnian–Famennian boundary. Preliminary interpretations are focused on developing several multiproxy linkages that will potentially lead toward a more robust understanding of the occurrence and significance of phytoplankton assemblage variations during the Late Devonian, a time of widespread black shale formation. Development of such linkages will potentially provide a more comprehensive assessment of the various controls on 1) primary production, and 2) carbon sequestration in a large, low-paleolatitude intracratonic basin.An abrupt change in the geochemical and biotic proxies for particulate organic matter across the Frasnian–Famennian boundary coincides with a distinct lithological change, characterized by laminated, brownish-black Famennian mudstones unconformably overlying alternating bioturbated, greenish-gray and non-bioturbated, dark-gray Frasnian mudstones. Elemental and isotopic profiles reflect different patterns of production, degradation, and removal of organic carbon in the two shale facies. A shift from acritarch- to prasinophyte-dominated waters across the boundary indicates the overall importance of bathymetric fluctuations, chemico-physical conditions, and nutrient availability related to eustatic sea-level change. A positive δ¹³C_V-PDB shift of 1.1‰ across the boundary is interpreted to be correlative with the global Upper Kellwasser Event. A preliminary model is proposed to explain the sustainable primary production during times of maximum flooding, thereby enhancing organic preservation during black shale formation.     

Upper Famennian and Lower Tournaisian sections of the Moravian Karst (Moravo‐Silesian Zone,Czech Republic): a proposed key area for correlation of the conodont and foraminiferal zonations

Foraminiferal and conodont faunas at the Devonian–Carboniferous (D–C) boundary in the southern part of the Moravian Karst (Czech Republic) were studied in different facies of the basin slope. The joint presence of foraminifers and conodonts in calciturbidites along with a positive δ¹³C excursion of the Hangenberg anoxic event enabled the high‐resolution calibration of the late Famennian–early Tournaisian interval (Upper expansa–crenulata conodont zones). The conodont stratigraphic and biofacies succession reveals a strong correlation with other European areas. The Siphonodella sulcata morphotype (close to Group 1 sensu Kaiser and Corradini and “nov. gen. nov. sp. 1” sensu Tragelehn) enters prior to the Hangenberg Event, which resembles Upper and Uppermost Famennian conodont successions from Franconia, Bavaria and Morocco. The diversification of the early siphonodellids takes place after the Hangenberg Event and after the protognathodid radiation. In terms of foraminiferal biostratigraphy, the D–C boundary interval is characterized by the first appearance datum (FAD) of Tournayellina pseudobeata close below the D–C boundary followed by a sequence of Tournaisian bioevents, where apart from the last appearance datums (LADs) of quasiendothyrs, the FADs of the Neoseptaglomospiranella species and chernyshinellids play an important role in a similar manner as in Eastern Europe. The correlation of these bioevents elsewhere is often hindered by glacioeustatically‐driven unconformities and widespread occurrences of unfavourable facies for plurilocular foraminifers (Malevka beds and Bisphaera beds). Copyright © 2013 John Wiley & Sons, Ltd.     

Oxygen isotope evolution of biogenic calcite and apatite during the Middle and Late Devonian

Oxygen isotope ratios of well-preserved brachiopod calcite and conodont apatite were used to reconstruct the palaeotemperature history of the Middle and Late Devonian. By assuming an oxygen isotopic composition of –1 V-SMOW for Devonian seawater, the oxygen isotope values of Eifelian and early Givetian brachiopods and conodonts give average palaeotemperatures ranging from 22 to 25 °C. Late Givetian and Frasnian palaeotemperatures calculated from ¹⁸O values of conodont apatite are close to 25 °C in the early Frasnian and increase to 32 °C in the latest Frasnian and early Famennian. Oxygen isotope ratios of late Givetian and Frasnian brachiopods are significantly lower than equilibrium values calculated from conodont apatite ¹⁸O values and give unrealistically warm temperatures ranging from 30 to 40 °C. Diagenetic recrystallization of shell calcite, different habitats of conodonts and brachiopods, as well as non-equilibrium fractionation processes during the precipitation of brachiopod calcite cannot explain the ¹⁸O depletion of brachiopod calcite. Moreover, the ¹⁸O depletion of brachiopod calcite with respect to equilibrium ¹⁸O values calculated from conodont apatite is too large to be explained by a change in seawater pH that might have influenced the oxygen isotopic composition of brachiopod calcite. The realistic palaeotemperatures derived from ¹⁸O _apatite may suggest that biogenic apatite records the oxygen isotopic composition and palaeotemperature of Palaeozoic oceans more faithfully than brachiopod calcite, and do not support the hypothesis that the ¹⁸O/¹⁶O ratio of Devonian seawater was significantly different from that of the modern ocean.