The global warming event across the Kasimovian-Gzhelian boundary (KGB) of the late Pennsylvanian recorded prominent perturbations of global biogeochemical cycles, accompanied by abrupt global warming, widespread marine anoxia, and a distinct biodiversity loss. However, marine primary productivity and redox evolution during the KGB warming event have not yet been explored from the perspective of marine nitrogen cycle. Nitrogen (N) plays a key role in regulating marine primary productivity and is also sensitive to marine redox variations, which thus has the potential for tracking oceanic changes during climatic transitions. Here, we present high-resolution sedimentary delta N-15 records from three carbonate slope successions across the KGB in South China in order to investigate N cycling during the KGB warming event. Our data show consistently four-phase changes in delta N-15 from the three study sections: (I) a slow decline from similar to 12 parts per thousand to similar to 8 parts per thousand, (II) a rapid increase to 15 parts per thousand, (III) a distinct negative excursion from 15 parts per thousand to 8 parts per thousand, and (IV) constant. The delta N-15 records suggest dynamic changes in water-column denitrification and N-fixation in response to marine redox conditions. Notably, the distinct negative excursion in delta N-15 (Phase III) immediately below the KGB suggests enhanced nitrogen fixation, which possibly resulted from expanded anoxia during the KGB warming event.

Deep-time hyperthermal/transient warming events provide critical analogs for modern climatic warming and its impacts. However, all ancient hyperthermals documented to date have occurred under greenhouse climate states, limiting their relevance for understanding the trajectory of present-day climate change. Here, we present conodont oxygen isotope data and climate modeling for the Kasimovian-Gzhelian Thermal Maximum (KGTM) at ~304 Ma. This transient warming event is inferred to have been marked by a ~7.5 ± 1 °C rise in global mean surface temperature and an increase in atmospheric CO2 concentrations from ~[Formula: see text] to ~700 ± 100 ppm over ~175 kyr during the Late Paleozoic Ice Age. Carbon and mercury isotope records indicate large-scale carbon release and the development of photic-zone euxinia during the KGTM, coincident with a marine biocrisis. The KGTM was initiated by a modest carbon release and temperature increase potentially associated with enhanced volcanic activity at an orbital eccentricity maximum, which likely crossed a climatic tipping point and triggered massive carbon release and abrupt large-scale warming. These findings demonstrate that transient warming events and severe oceanic deterioration can be caused by a modest thermal perturbation within an icehouse climate state analogous to that of the modern Earth.

The Naqing section in Luodian (Guizhou, South China) contains a deep-water carbonate-dominated succession of the Late Devonian through the Permian. In this study, 72 conodonts species/subspecies of 11 genera were obtained from the lower part of this section including. Seven middle to late Famennian and four early to late Tournaisian conodont biozones were recognized as, in ascending order, Palmatolepis marginifera marginifera Zone, Palmatolepis marginifera utahensis Zone, Polygnathus granulosus Zone, Palmatolepis rugosa trachytera Zone, Polygnathus styriacus Zone, Palmatolepis gracilis manca Zone, Palmatolepis rugosa rugosa Zone, Siphonodella isosticha Zone, Gnathodus punctatus Zone, Gnathodus typicus-Gnathodus cuneiformis Zone, and Gnathodus typicus-Protognathodus cordiformis Zone. Several key conodont biozones across the Devonian–Carboniferous Boundary (DCB) interval found elsewhere are not discovered in the Naqing section, likely due to a conodont-barren interval in the siliciclastic facies. The middle Famennian–late Tournaisian conodont biozones illustrated in this study provide a robust chronostratigraphic framework for further research on biotic and paleo-environmental events during the Late Devonian through Early Mississippian critical greenhouse-icehouse climate transition.

Based on the conodonts recovered for the first time and some brachiopods, this study revises the age of the Wuqingna Formation in eastern Tibet to a late Famennian, challenging prior Carboniferous classification based on coral assemblages. In this study, conodonts are described for the first time from the Wuqingna Formation on the Wuqingka Mountain near Toba Town, Qamdo City in eastern Tibet. The conodont assemblage contains 6 species/subspecies (including morphotypes within open nomenclature) that belong to three genera. The conodont species Polygnathus cf. perplexus, Po. homoirregularis, Po. wuqingnaensis n. sp. and Scaphignathus peterseni suggest an age of late Famennian, probably the Palmatolepis gracilis manca Zone to the Pa. gr. expansa Zone, for the lower part of the Wuqingna Formation, which was previously assigned to the Carboniferous based on the rugose coral assemblages.

The typical Mississippian shallow-water deposits of the Jiusi and Shangsi formations are well exposed in the Yashui section in southern Guizhou, South China. The strata are composed mainly of platform limestones intercalated with shales and sandstones. Conodonts obtained from the limestones are dominated by two assemblages of cavusgnathids: the Cavusgnathus aff. Cav. unicornis and Clydagnathus windsorensis assemblage from the upper Jiusi Formation and the Cavusgnathus unicornis assemblage from the lowest Shangsi Formation. Vogelgnathus campbelli (Rexroad, 1957) is reported for the first time in Eastern Paleotethys and is characterized by small lateral denticles. The evolutionary first occurrence of Cavusgnathus unicornis Youngquist and Miller, 1949 is recognized as a marker for the regional Shangsian stage. This biostratigraphic datum is interpreted to be correlative with other shallow-water conodont zones marked by Cavusgnathus unicornis s.l. and similar species from North America and Europe.

Abstract Late Moscovian–early Gzhelian conodonts occur abundantly in a newly discovered slope section, the Shanglong section, southern Guizhou, South China. The conodont fauna is dominated by P1 elements of Idiognathodus and associated with elements of Swadelina , Streptognathodus and Heckelina . A total of 62 species, including species in open nomenclature, were identified, which are assigned to eight genera. Index conodont species of Middle and Late Pennsylvanian, e.g. I. podolskensis Group, Sw. sp. A, Sw . subexcelsa , Sw . makhlinae , I . heckeli , I . magnificus , I . guizhouensis , H. eudoraensis , I . naraoensis , and H . simulator are all recovered, and their 10 conodont zones are recognized. The richness and abundance of the conodonts throughout the section are analysed. Conodont richness ranges from 1 to 14 and is positively related to conodont abundance (1–379). The composition of conodont elements, i.e. sinistral v. dextral, P1 v. non-P1 and adult v. subadult and juvenile, is presented. The numerical cluster technique is employed to identify four subbiofacies of the slope setting, namely the I . podolskensis , Swadelina , I. swadei–magnificus and Streptognathodus – Heckelina–Idiognathodus subbiofacies.

The Late Paleozoic Ice Age (LPIA) is the so far longest-last icehouse climate state during the Phanerozoic, and recorded a complete transition from icehouse to greenhouse climate state since the occurrence of vascular plants and complex terrestrial ecosystem. Therefore, integrated studies on the icehouse-greenhouse transition of the LPIA are critical to understanding the driver and mechanism of the deep-time paleoclimate system, particularly in an icehouse climate state. However, frequent subaerial exposures and stratigraphic discontinuities in low-latitude areas due to glacio-eustatic changes from the Pennsylvanian (Late Carboniferous) to Cisuralian (Early Permian) potentially altered the primary δ13C signals, which hampered a valid global correlation. Here, three carbonate slope successions (Naqing, Shanglong, and Narao) in the Luodian Basin, South China Block, were selected for detailed sedimentology and high-resolution carbonate δ13C study. The variation of δ13C is compared with the sedimentary characteristics and can be correlated with global glacial events and atmospheric pCO2 during the apex and deglaciation period of the LPIA. It suggests that δ13C of the Luodian Basin can potentially represent the global mean δ13C of the seawater dissolved inorganic carbon and provide a reference for the future study on global carbon cycling.

UUID: http://zoobank.org/bae1f4cb-c5c1-4dfd-85e2-22bfc929e4a0

Significance Massive carbon (C) release with abrupt warming has occurred repeatedly during greenhouse states, and these events have driven episodes of ocean deoxygenation and extinction. Records from these paleo events, coupled with biogeochemical modeling, provide clear evidence that with continued warming, the modern oceans will experience substantial deoxygenation. There are, however, few constraints from the geologic record on the effects of rapid warming under icehouse conditions. We document a C-cycle perturbation that occurred under an Earth system state experiencing recurrent glaciation. A suite of proxies suggests increased seafloor anoxia during this event in step with abrupt increase in CO2 partial pressure and a biodiversity nadir. Warming-mediated increases in marine anoxia may be more pronounced in a glaciated versus unglaciated climate state.

根据对中国小阳桥剖面高精度生物、层序、化学和磁性地层学综合研究的新成果及其与绿岬全球界线层型剖面(GSSP)的详细对比,进一步厘定了加拿大绿岬"金钉子"剖面所定义的奥陶系底界划分与对比的标志,并指出:(1)与所定义的全球标准奥陶系底界相当的界线位于小阳桥剖面块状叠层石灰岩之上19.9 m处的薄层纹层灰岩中(BD-24层的底部),即Cordylodus intermedius牙形石带的上部,其上1 m则出现世界上最早的浮游笔石Rhabdinopora proparabola,其上1.5 m则是牙形石Cordy-lodus lindstromi的首现层位;(2)所定义的奥陶系底界位于两次全球海平面升降事件(全球巴萨尔屋(Basal House)低位和弓头虫(Acerocare)低位事件)之间;(3)奥陶纪初期最大的δ13Ccarb同位素正偏移出现在Rhabdinopora parabola笔石带的底部;(4)Cordylodus intermedius牙形石生物带内记录的、被称之为Hirsutodontus simplex峰(=HSS,简单多刺牙形石峰)的显著δ13Ccarb碳同位素正偏移和稀土元素(REE)异常,均位于这两个剖面寒武-奥陶系界线之下.以上所有这些事件记录均可作为全球不同大陆和相区识别与划分对比寒武系-奥陶系界线的标志.

During the Mississippian period, metazoan reefs and other marine faunas gradually recovered from the Late Devonian mass extinctions and reached a peak in the late Visean (~334-332 Ma). Faunal diversity started to decline from the latest Visean (~332-330 Ma) through Serpukhovian (~330-323 Ma), with significant genera/ species losses and ecosystem reconstruction. This Middle-Late Mississippian biodiversity crisis (M-LMBC) was thought to have been caused by global cooling associated with the late Paleozoic Ice Age (LPIA), but existing sedimentological and temperature proxy data suggest that the global cooling event-that marks the onset of the main glaciation phase of LPIA-happened either-4 Myr before or ~1-5 Myr after the initial biodiversity decline at-332 Ma. Here, we report oxygen isotope data of diagenetically screened, well-preserved brachiopod calcite (delta(18)Ocalcite) from late Visean-Serpukhovian (or Middle-Late Mississippian;-334-323 Ma) strata in South China where biodiversity data are well documented. The delta(18)Ocalcite data reveal a -2.0(sic) positive shift from-4.6 +/- 0.2(sic) to-2.7 +/- 0.5(sic) with an estimated ~4.7-5.5 C drop in sea surface temperature (SST) during ~332.5-331.5 Ma in the late Visean. This cooling event coincides with fast decline of metazoan reef abundance, followed by decrease of benthic faunal diversity. The delta(18)Ocalcite data, in combination with calibrated sedimentological and biodiversity data, demonstrate the coupling between late Visean (~332 Ma) onset of the main glaciation phase of the LPIA and initiation of the M-LMBC.

The Global Stratotype Section and Point (GSSP) for the base of the Capitanian Stage was proposed in 1999 and defined by the first appearance datum (FAD) of the conodont Jinogondolella postserrata within the lineage J. aserrata -> J. postserrata -> J. shannoni at Nipple Hill in West Texas, USA. Despite its widespread recognition for more than two decades, the official GSSP paper was not published, nor have its index conodont fossils been properly documented. At Nipple Hill, only the uppermost 0.5 m of the Pinery Member belongs to the Capitanian Stage. J. postserrata first appears at 19.8 m above the base of the auxiliary Frijole section. Based on U-Pb CA-ID-TIMS geochronology of ash beds from the GSSP area, the base of the Capitanian Stage has been constrained at 264.28 +/- 0.16 Ma. Magnetostratigraphy suggests that the Illawarra Reversal is located slightly below the base of the Capitanian Stage. Strontium isotope chemostratigraphy generally shows a continuous decline in the Sr-87/Sr-86 ratio throughout the Capitanian in the GSSP area, but all ratios are higher than the Capitanian minimum of similar to 0.7068. delta(13)C(carb)profile shows no distinct excursion around the Wordian/Capitanian boundary interval. Detailed correlation suggests that the middle-upper part of the fusuline-based Midian Stage correlates with the Capitanian Stage.

《国际年代地层表》中的石炭系包含密西西比亚系和宾夕法尼亚亚系,各分3统,共7个阶,是全球煤炭、油气等重要能源资源的富集层位.为了统一标准、提高对比精度,并服务于资源勘探开发,本文在详细归纳前人研究的基础上,结合最新的研究成果,对中国石炭纪地层区划、主要剖面的地层划分和对比进行了系统梳理;将中国的石炭系划分为4个地层大区,分别为准噶尔—兴安大区、塔里木—华北大区、羌塘—华南大区和西藏—滇西大区,又进一步将各地层大区划分为11个地层区,并列举了81条地层剖面.基于生物地层学和年代地层学的时间约束,详细厘定了中国石炭系不同地层分区之间的岩石地层划分和对比框架.准噶尔—兴安大区石炭系以浊积岩和火山岩为主,是中亚造山带的重要组成部分;华北—塔里木大区除塔里木北缘和华北台地西南部保存有深水沉积外,均为稳定的滨浅海沉积,其中华北分区缺乏密西西比亚系,宾夕法尼亚亚系为海陆交互相沉积,发育明显的海侵-海退序列;西藏—滇西大区为冈瓦纳大陆东北缘沉积区,密西西比亚系以陆棚碳酸盐岩或碎屑岩为主,宾夕法尼亚亚系则常常缺失;羌塘—华南大区石炭系序列最为完整,尤其华南地区,以碳酸盐岩台地沉积为主,化石丰富多样,是国际石炭系对比的重要标准.

地史中海相碳酸盐岩记录的无机碳同位素的波动经常与全球气候事件相互关联,但碳酸盐岩的碳同位素不仅与全球碳循环相关,也受控于区域水循环和成岩作用.晚古生代大冰期在石炭纪末—早二叠世达到最高峰,南方冈瓦纳大陆高纬度地区冰川的进退引起低纬度地区旋回性的海平面变化,并发育显著的沉积间断,在华南表现为喀斯特岩溶角砾岩等.本文选取安徽巢湖凤凰山剖面,对宾夕法尼亚亚系—乌拉尔统18 m厚的碳酸盐岩地层(黄龙组和船山组)进行了详细的沉积学与碳同位素对比研究,以探索碳同位素变化的控制因素.本文共识别出厚层灰泥灰岩、厚层粒泥灰岩、中至厚层泥粒灰岩、厚层泥球颗粒灰岩、薄层鲕粒颗粒灰岩、厚至巨厚层生物碎屑颗粒灰岩、厚层核形石颗粒灰岩、薄至中层灰砾岩和炉渣状灰岩等9种沉积岩相,指示了多次暴露的碳酸盐台地环境.这些暴露特征与同时期贵州罗甸斜坡相碳酸盐岩序列(约194m)对比,表明凤凰山剖面存在严重的地层缺失.揭示了研究层段11m和14 m附近的碳同位素两次显著负漂(幅度约为6‰和7‰)与古喀斯特层对应,是由碳酸盐台地暴露引起的区域成岩改造导致的,而非源于引起气候变化的全球碳循环波动.因此,地层学、沉积学和地球化学等多学科综合交叉研究是深入揭示古气候和古海洋变化规律的重要前提.

Abundant conodonts occur in the Naqing section, southern Guizhou, South China, which has been selected as the candidate of the Carboniferous Kasimovian GSSP. Swadelina subexcelsa, Idiognathodus heckeli, I. turbatus and I. sagittalis, which are potentially index taxa for the Moscovian-Kasimovian boundary, are all recorded in the Naqing section. The lineages from their ancestors have been discussed in this paper, and furthermore, based on their lineages the conodont zonation is established for the global correlation. The provincialism of the Moscovian-Kasimovian boundary interval is also analyzed. The Tethyan and American Midcontinent provinces, can be identified to differentiate conodont faunas among major basins. The Tethyan Province can be further subdivided into the South China and Eastern European Platform subprovinces. By incorporating and evaluating varying aspects of the taxonomy, biostratigraphy and palaeobiogeography of the potential index taxa, I. heckeli might be the best marker for the base Kasimovian in term of its clear taxonomic definition and phylogenetic lineage, as well as its wide geographic range.

Abstract Carboniferous conodont biostratigraphy comprises regional zonations that reflect the palaeogeographical distribution of taxa and distinct shallow-water and deep-water conodont biofacies. Some species have a global distribution and can effect high quality correlations. These taxa are incorporated into definitions of global Carboniferous chronostratigraphic units. A standard global Carboniferous zonation has not been developed. The lowermost Mississippian is zoned by Siphonodella species, excepet in shallow-water facies, where other polygnathids are used. Gnathodus species radiated during the Tournaisian and are used to define many Mississippian zones. A late Tournaisian maximum in diversity, characterized by short-lived genera, was followed by lower diversity faunas of Gnathodus species and carminate genera through the Visean and Serpukhovian. By the late Visean and Serpukhovian, Lochriea provides better biostratigraphic resolution. Shallow-water zonations based on Cavusgnathus and Mestognathus are difficult to correlate. An extinction event near the base of the Pennsylvanian was followed by the appearance of new gnathodid genera: Rhachistognathus, Declinognathodus, Neognathodus, Idiognathoides and Idiognathodus. By the middle of the Moscovian, few genera remained: Idiognathodus, Neognathodus and Swadelina. During the middle Kasimovian and Gzhelian, only Idiognathodus and Streptognathodus species were common. Near the end of the Gzhelian, a rediversification of Streptognathodus species extended into the Cisuralian.