贵州罗甸二叠纪末生物大灭绝事件后沉积的微生物岩时代和沉积学特征

二叠纪末期发生的显生宙以来最大的生物绝灭事件,使海洋生态系统和陆地生态系统均受到重创之后,微生物岩广泛分布于全球正常浅海地区。研究认为,扬子地台在二叠纪末期存在一次海平面降低的事件,造成研究区二叠纪地层与早三叠世微生物岩之间存在沉积间断或剥蚀,并使三叠纪牙形石混入二叠纪末期的沉积物中。二叠-三叠系界线位于微生物岩层的底界;微生物岩形成于早三叠世最早期,相当于Hindeodus parvus带,是早三叠世最早期开始的海侵事件为其提供生长所需的可容纳空间。在Isarcicella staeschei带-I. isarcica带早期再次发生相对海平面降低事件,之后海平面开始快速上升。研究区早三叠世早期的微生物岩以凝块构造发育为特征,具有斑状、层状、枝状和网状凝块构造4种典型中型构造。结合前人的工作,认为微生物群落通过生物沉积和物理沉积作用形成球状体,球状体汇聚形成不同的中型凝块构造。研究扬子地台早三叠世凝块石的确切时代和结构、构造类型特征,为准确恢复生物大灭绝事件前后的环境变迁以及生物演化事件与环境变化的相互作用关系提供重要的证据。     

Comment on “First Record of Hindeodus–Isarcicella Population in Lower Triassic of Slovenia” by Tea Kolar-Jurkov?ek and Bogdan Jurkov?ek in Palaeogeography, Palaeoclimatology, Palaeoecology, 252: 72–81

Some conodonts described by Tea Kolar-Jurkovsek and Bogdan Jurkovsek (2007) from the Permian-Triassic boundary section in the ?iri area of western Slovenia are revised in this paper. One specimen that they assigned to Hindeodus parvus is tentatively regarded as Hindeodus cf. scalaris Wu 2005. Two specimens that they assigned to Isarcicella sp. A is changed to Hindeodus parvus. One specimen that they described as Isarcicella lobata Perri and Farabegoli is changed to Hindeodus crenatus Wu (2006). One specimen that they assigned to Isarcicella turgida (Kozur, Mostler and Rahimi-Yazd) is changed to Hindeodus cf. parvus. Since these revisions, the three conodont zones that they defined have been correspondingly revised. Their first zone may belong to Hindeodus parvus zone, but it is not certain. Their second zone is changed to the Hindeodus parvus zone, and their third one remains as is.     

Restudy of conodont biostratigraphy of the Permian–Triassic boundary section in Zhongzhai,southwestern Guizhou Province,South China

New conodont samples have been systematically collected at high stratigraphic resolution from the upper part of the Longtan Formation through to the lower part of the Yelang Formation at the Zhongzhai section, southwestern Guizhou Province, South China, in an effort to verify the first local occurrence of Hindeodus parvus in relation to the Permian–Triassic boundary at this section. The resampled conodont fauna from the Permian–Triassic boundary interval comprises five identified species and two undetermined species in Hindeodus and Clarkina. Most importantly, the first local occurrence of Hindeodus parvus is found for the first time from the bottom of Bed 28a, 18 cm lower than the previously reported first local occurrence of this species at this section. Considering the previously accepted PTB at the Zhongzhai section, well calibrated by conodont biostratigraphy, geochronology and carbon isotope chemostratigraphy, this lower (earlier) occurrence of H. parvus suggests that this critical species could occur below the Permian–Triassic boundary. As such, this paper provides evidence that (1) the first local occurrences of H. parvus are diachronous in different sections with respect to the PTB defined by the First Appearance Datum (FAD) of this species at its GSSP section in Meishan, China and that (2) the lower stratigraphic range of H. parvus should now be extended to latest Permian.     

浙江长兴煤山二叠-三叠系界线层牙形石序列及其全球对比

在详细研究全球二叠－三叠系界线层候选剖面───中国浙江长兴煤山剖面Ｐ／Ｔ界线层牙形石动物群序列基础上，自下而上识别出４个牙形石带：（１）ＣｌａｒｋｉｎａｃｈａｎｇｘｉｎｇｅｎｓｉｓＣｌａｒｋｉｎａｄｅｆｌｅｃｔａ带；（２）Ｉｓａｒｃｉｃｅｌｌａｐａｒｖａ带；（３）Ｉｓａｒｃｉｃｅｌｌａｉｓａｒｃｉｃａ带；（４）ＣｌａｒｋｉｎａｃａｒｉｎａｔａＣｌａｒｋｉｎａｐｌａｎａｔａ带，并在第一带中划分出３个动物群，从下向上是：ＣｌａｒｋｉｎａｃｈａｎｇｚｉｎｇｅｎｓｉｓＣｌａｒｋｉｎａｄｅｆｌｅｃｔａ－Ｃｌａｒｋｉｎａｓｕｂｃａｒｉｎａｔａ动物群，Ｈｉｎｄｅｏｄｕｓｌａｔｉｄｅｎｔａｔｕｓ－Ｃｌａｒｋｉｎａｍｅｉｓｈａｎｅｎｓｉｓｓｐ．ｎｏｖ．动物群和Ｈｉｎｄｅｏｄｕｓｔｙｐｉｃａｌｉｓ动物群，煤山剖面二叠、三叠系界线层牙形石序列的建立、完善，对确立该剖面在全球二叠、三在系界线高精度对比中的标准地位具重要意义。     

二叠-三叠纪之交牙形石生态新模式

通过对浙江长兴煤山剖面二叠－三叠系界线层沉积相分析及牙形石演化规律研究,提出了该时期Ｃｌａｒｋｉｎａ（Ｎｅｏｇｏｎｄｏｌｅｌａ）,Ｈｉｎｄｅｏｄｕｓ两类重要牙形石属的生态新模式．（１）Ｃｌａｒｋｉｎａ是一种底栖自由游泳生物,可出现于远岸浅海至盆地相较深水环境;（２）Ｈｉｎｄｅｏｄｕｓ是一种洋面浮游型生物,死亡之后可沉于海底的滨、浅海至深水盆地各种环境之中,并可渡过二叠－三叠纪之交海底缺氧事件这一难关,在早三叠世得到发展;因此,Ｈｉｎｄｅｏｄｕｓ可作为全球二叠－三叠系界线划分对比的可靠证据．     

Palynological assemblages of non-marine rocks at the Permian–Triassic boundary, western Guizhou and eastern Yunnan, South China

Marine and non-marine facies of the Permian–Triassic boundary stratigraphic set (PTBST) are well developed in South China. Palynological assemblages enable subdivision and correlation of the Permian–Triassic boundary (PTB) rocks. Three palynological assemblages are recognized across the PTBST in two terrestrial PTB sections in western Guizhou and eastern Yunnan, South China. Assemblage 1 (Xuanwei Formation) is a Late Permian palynological assemblage dominated by ferns and pteridosperms, with minor gymnosperms. Most taxa are typical long-ranging Paleozoic forms, but the appearance of Lueckisporites confirms a Late Permian age for this assemblage. Assemblage 2 (PTBST) is marked by an abrupt decrease in palynomorph abundance and diversity, and thriving fungal/algal(?) spores. Assemblage 2 is still dominated by ferns and pteridosperms, with a few gymnosperms, but is characterized by a mixed palynoflora containing both Late Permian and Early Triassic elements. Most taxa are typical Late Permian ones also found in Assemblage 1, however, some taxa of Early Triassic aspect, e.g. Lundbladispora and Taeniaesporites, appeared for the first time. In Assemblage 3 (top Xuanwei Formation and Kayitou Formation), the proportion of gymnosperm pollen increases rapidly, exceeding that of ferns and pteridosperms, but the abundance of palynomorphs is still low. Typical Early Triassic taxa (such as Lundbladispora, Aratrisporites and Taeniaesporites) are present in greater abundance and confirms an Early Triassic age for this assemblage.     

湖北崇阳二叠纪-三叠纪之交钙质微生物岩的时代及基本特征

湖北崇阳钙质微生物岩产在二叠纪末礁相绝灭界线之上, 绝灭界线之下即为晚二叠世长兴期的海绵礁灰岩、棘屑灰岩及藻有孔虫生物碎屑灰岩.微生物岩基本上由中粗晶-微晶方解石组成, 主要沉积构造有“花斑状构造”及藻叠层构造.目前微生物岩中发现的化石主要有球状菌藻类化石、介形虫、微型腹足、双壳、鱼牙及分类位置尚无法确定的棒状微型化石.微生物岩中已发现有牙形石化石: Hindeodusparvus, H.typicalis和H.latidentatus, 从牙形石的类型及产出层位分析, 崇阳钙质微生物岩的下部属于晚二叠世长兴期, 上部为早三叠世.崇阳微生物岩在沉积特征、生物组成及牙形石带上均基本可与华南其他地区已发现的微生物岩进行对比.      

海相二叠系、三叠系生物地层界线划分的新方案

国际上传统地以Otoceras带之底作为二叠系、三叠系界线。但根据新资料综合对比,Otoceras带下部可能与二叠系顶部的Pseudotirolites或Paratirolites带重叠,不宜作为标志。在特提斯区广泛分布的Hindeodus Parvus,与上述菊石带上下不重叠,可作为三叠纪开始的标志。其底界在华南为粘土层,与事件地层界线一致。因此建议以H.parvus替代Otoceras,以H.parvus带之底作为三叠系之底。     

对《西藏色龙西山色龙群的时代及二叠系与三叠系的界线》一文的质疑

<正> 1992年夏凤生等在贵刊16卷4期上发表《西藏色龙西山色龙群的时代及二叠系与三叠系的界线》一文,批评王义刚等(1989)研究的同一剖面的工作结果。因为我们也是被评述论文的作者,有责任从几个方面对夏文进行质疑和评述。     

The Wuchiapingian–Changhsingian boundary (Upper Permian) at Meishan of Changxing County, South China

Section D at Meishan, Changxing County in the Zhejiang Province, China, has been extensively studied in various aspects of the stratigraphy during the past 20 years. It was ratified by the International Union of Geological Sciences (IUGS) as the Global Standard Stratotype Section and Point (GSSP) for the Permian–Triassic boundary in 2000, and is also a potential stratotype for the Wuchiapingian–Changhsingian boundary. However, the contact relationship between the Longtan (Wuchiapingian) and Changxing (Chainghsingian) formations has been a controversial subject for years. Recent studies on Section C, about 300 m west of Section D, at Meishan confirm a complete depositional succession around the boundary and suggest that the proposed boundary level, the FAD of Clarkina wangi within the lineage from C. longicuspidata to C. wangi, is consistent with the first appearance of the index Changhsingian fusulinid Palaeofusulina sinensis and tapashanitid ammonoids.     

Age and General Characteristics of the Calimicrobialite near the Permian-Triassic Boundary in Chongyang, Hubei Province

INTRODUCTIONCali microbialites near the Permian-Triassicboundary are a special sedi mentary framework whichis formed on the top of reefs or isolated carbonateplatforms after the end-Permian extinction. Cali mi-crobialite in South China was first found by Lehr-mann (1999) in Bianyang, Guizhou. Al most si multa-neously , Kershawet al .(1999) reported cali microbi-alites in East Sichuan. Discovery of Permian-Triassiccali microbialites in South China has attracted muchattention. Based o…     

Comment on "First Record of Hindeodus-Isarcicella Population in Lower Triassic of Slovenia" by Tea Kolar-Jurkovsek and Bogdan Jurkov(s)ek in Palaeogeography, Palaeoclimatology, Palaeoecology, 252:72-81

Some conodonts described by Tea Kolar-Jurkovsek and Bogdan Jurkovsek (2007) from the Permian-Triassic boundary section in the Ziri area of western Slovenia are revised in this paper. One specimen that they assigned to Hindeodus parvus is tentatively regarded as Hindeodus cf. scalaris Wu 2005. Two specimens that they assigned to IsarciceUa sp. A is changed to Hindeodus parvus. One specimen that they described as IsarciceUa lobata Perri and Farabegoli is changed to Hindeodus crenatus Wu (2006). One specimen that they assigned to lsarcicella turgida (Kozur, Mostler and Rahimi-Yazd) is changed to Hindeodus cf. parvus. Since these revisions, the three conodont zones that they defined have been correspondingly revised. Their first zone may belong to Hindeodus parvus zone, but it is not certain. Their second zone is changed to the Hindeodus parvus zone, and their third one remains as is.     

地层单位与全球界线层型:概念、术语、有关规定与研究实例

全球二叠系-三叠系界线(PTB)层型及点("金钉子")定位我国浙江省长兴县煤山D剖面,极大地推动了PTB及二叠系和三叠系研究进展。在简要介绍地层单位与全球界线层型与点建立的相关概念、术语和有关规定、地层划分的主要种类及其地层单位术语的基础上,以全球二叠系—三叠系界线层型及点(中国浙江省长兴县煤山D剖面)为研究实例,综述了该金钉子剖面牙形石生物地层和年代地层研究现状。煤山D剖面构建了目前全球最完整的PTB地层牙形石带序列,为研究二叠纪末大灭绝后生物残存和复苏过程提供了重要的时间坐标系,也为相关的地质事件研究奠定了坚实的基础。     

西秦岭地区二叠—三叠系界线地层研究

在西秦岭地区南秦岭带广泛发育碳酸盐岩型二叠、三叠系。本文以选部益哇沟剖面为例，对该区界线地层进行研究，从岩石地层划分、生物地层划分以及地球化学元素最优分割研究出发，确定了二叠、三叠系界线点，证明牙形石Ｈｉｎｄｅｏｄｕｓｐａｒｖｕｓ可作为三叠系开始的标志，并且二叠、三叠系是连续的。沉积环境分析表明，三叠纪初期相对于二叠纪末发生了一次海侵。     

Triassic biochronology: State of the art and main problems

According to known resolution of the IUGS, the International Stratigraphic Commission entrusted its subcommissions with a task to prepare proposals for the official approval of boundaries between Phanerozoic stages. Specially organized working groups were later renamed as special teams for seeking the Global Stratotype Sections and Points (GSSP) for these boundaries. In 2001, the GSSP of lower boundary for the Induan Stage, the basal one in the Triassic System, was officially approved to be in the Meishan section of southern China. The selection appeared to be lame, because the Permian-Triassic boundary layers of the stratotype section are lacking ammonoids. As a result, this boundary is now based only on the first occurrence level (FO) of conodont species Hindeodus parvus. Soon, the proposal of Chinese paleontologists to consider the western Pingdingshan section in the Anhui Province as the GSSP for the lower boundary of the Olenekian Stage may win the official recognition. This boundary between the Olenekian and Anisian stages, which is placed at the FO of conodont species Neospathodus waageni is the least debatable. The Mt. Desli Caira section in northern Dobrogea (Romania) is most appropriate for its global stratotype. In contrast, the Anisian-Ladinian boundary appeared to be most disputable. The Subcommission on Triassic Stratigraphy should select one of three GSSP candidates proposed. The lower Carnian boundary traditionally drawn at the aon Zone base suffered some changes. It is proposed to place it at the FO of the ammonoid genus Daxatina with the GSSP in the Dolomites of Italy. The Norian and Rhaetian boundaries are under discussion.     

浙江长兴二叠系-三叠系界线层型剖面面临的新问题

长兴煤山P/T界线在27层中间,H.parvus带之上应为I.staeschei带,不是I.isarcica带。H.parvus带厚仅4cm,可能包括H.parvus和I.lobata两个化石带的时间间隔;界线层不仅高度浓缩,而且有硬底构造,缺失一些牙形刺分子,很可能在界线层中有小的沉积间断。     

福建漳平岬顶二叠纪-三叠纪界线划分

漳平岬顶上二叠统罗坑组-下三叠统溪口组均为海相细碎屑沉积,界线附近地层沉积连续,未见间断,化石丰富,生物群演化特征明显。三叠纪新生分子自Claraia wangi-Eumorphotis multiformis组合带开始出现,其下晚二叠世晚期菊石相继消失,Crurithyris,Paracrurithyris等少数腕足类上延至三叠纪与Claraia混生,形成见跨代生物混生层。根据生物群演化,将漳平岬顶二叠纪-三叠纪界线置于Claraia wangi-Eumorphotis multiformis组合带之底,此界线与华南海相碎屑岩相区以Claraia类群之底划分的界线相当,与浙江长兴煤山以Hindeodus parvus标定的界线较为接近,亦可以对比。     

A Review on the Global Stratotype Section and Point of the Permian-Triassic Boundary

1 Introduction The Global Stratotype Section and Point (GSSP) of the Permian-Triassic Boundary (PTB) has been ratified by IUGS in 2001 (Yin et al., 2001). It is defined at the base of the Hindeodus parvus horizon, i.e. the base of Bed 27c of Meishan Section D, Changxing County, Zhejiang Province, South China. The PTB is important because it is not only an erathem boundary but also a great turning point of geological history symbolized by profound global changes and the strongest …     

Facies changes and diagenetic processes across the Permian–Triassic boundary event horizon, Great Bank of Guizhou, South China: a controversy of erosion and dissolution

The Permian–Triassic boundary interval in shallow shelf seas of South China shows Upper Permian limestones overlain by lowermost Triassic microbialites. Global sea‐level rose across the Permian–Triassic boundary, but an irregular top‐Permian erosion surface across a 10 km north–south transect of the Great Bank of Guizhou contains evidence of sea‐level fluctuation. The surface represents the ‘event horizon’ of mass extinction, below the biostratigraphic Permian–Triassic boundary defined by first appearance datum of conodont Hindeodus parvus. An Upper Permian foraminiferal grainstone beneath this surface contains geopetal sediments, etched grains, and pendent and meniscus cements interpreted here as vadose. However, these latter diagenetic processes occurred before the event horizon and were followed by erosion of the final Permian surface. This erosion cuts previous fabrics but lacks evidence of weathering or bioerosion. A few centimetres below is an earlier grainstone that was also eroded but lacks proof of sub‐aerial processes. Samples therefore reveal one, or possibly two, small‐scale relative sea‐level changes before the Triassic transgression in this area, and these may relate to local tectonics. The final Permian surface is subject to at least four interpretations: (i) sub‐aerial physical erosion and dissolution by carbon dioxide‐enriched fresh water or carbon dioxide‐enriched mixed water, prior to Triassic transgression; (ii) sub‐aerial physical erosion overprinted by dissolution related to carbon dioxide‐enriched sea water in the Early Triassic transgression; (iii) submarine dissolution affected by acidified sea water due to rapid increase in volcanically‐derived carbon dioxide and oxidized methane released from marine clathrates; (iv) submarine dissolution due to acid anoxic waters rising across the continental shelf, unrelated to atmospheric carbon dioxide or oxidized methane. Field and petrographic evidence suggests that (i) is the simplest option; and it is possible that (ii) and (iii) occurred, but none are proved. Option (iv) is unlikely given the evidence and modelling of supersaturation of upwelled waters with respect to bicarbonate.     

Research on Ecostratigraphy of Changhsingian at Meishan Section D, Changxing, Zhejiang Province

On the basis of researches over several years on biostratigraphy of Changhsingian at Meishan Section D in Changxing County, the abundant materials were accumulated. This paper studies the escostratigraphy and establishes 7 community zones (CZ), in ascending order, Sinoplatysomus-Gernitzina-Clarkina subcarinata, Tapashanites-Nodosaria-Clarkina subcarinata,Crurithyris-Geinitzina-Clarkina subcarinata,Glomospira-Clarkina changxingensis, Colaniella-Clarkina changxingensis,Rotodiscoceras-Palaeofusulina-Hindeodus typicalis,Clarkina meishanensis-Hypophiceras.The habitat type (HT) is diffent from upper shallow sea to the lower part of the lower shallow sea.