A detailed Lower Triassic conodont biostratigraphy and its implications for the GSSP candidate of the Induan–Olenekian boundary in Chaohu, Anhui Province

Chaohu is located in a deep part of carbonate ramp on the Lower Yangtze Block, which belonged to the low-latitude eastern Tethyan archipelago during the Early Triassic. Fossils were very rich in the Lower Triassic of Chaohu. Bivalves, ammonoids, conodonts were very common throughout the Lower Triassic, while fish fossils were generally rich in some beds of the upper part. It is one of the most typical sections for the Early Triassic chronostratigraphy in the world. Although various fossils had been studied in the 1980s and 1990s, recent studies based upon new and more detailed collections from the Lower Triassic of Chaohu showed that the conodont zonation needs revision. We collected Lower Triassic conodont fossils from continuous sections of the West Pingdingshan, North Pingdingshan and South Majiashan, Chaohu, Anhui Province, and updated zonations were made for each section. Eight conodont zones have been distinguished. They are, in ascending order, Hindeodus typicalis zone, Neogondolella krystyni zone, Neospathodus kummeli zone, Neospathodus dieneri zone, Neospathodus waageni zone, Neospathodus pingdingshanensis zone, Neospathodus homeri zone, and Neospathodus anhuinensis zone. The ?rst occurrence of Neospathodus waageni eowaageni of the N. w. eowaageni subzone (i.e. the base of the N. waageni zone) is suggested as the marker to de?ne the Induan–Olenekian boundary.     

The discovery of Jurassic plants in Shenzhen of Guangdong,southern China and related significance

Investigations of major marine and non-marine geologic and biotic events across the Triassic-Jurassic transition rely predominantly on detailed stratigraphic frameworks and biodiversity analyses. The alternating sequences of marine and terrestrial Triassic-Jurassic for- mations in Guangdong Province represent one of the most remarkable coal-bearing series in southern China. The Lower Jurassic Jinji Formation is widely distributed in Guangdong, with continuously outcropped sections and rich marine and non-marine fossil fauna. However, as little research has been conducted on fossil plant remains in the Jinji Formation, it is difficult to understand the systematics, diversity, and floral aspects of the Jurassic. Here we report on the recent collection of rich fossil plants from the Jinji Formation in the Dapeng area of Shenzhen, southern Guangdong Province. Our studies demonstrate taxonomical affiliations, preservation status, and diversity features of these plant fossils, which are marked by the close associ- ation of densely preserved, pinnae and rachis connected leaves, and the bennettitalean reproductive organs of Wil- liamsoniella, which may represent an Early Jurassic plant community dominated by Otozamites of the bennettitales. This work not only represents the first discovery of fossil plants in the Shenzhen area, but is also the first docu- mentation of Jurassic plants in Guangdong and the Pearl River Delta regions. Research related to these plant fossils will be helpful in the correlation of the Early Mesozoiccoal-bearing strata in Guangdong, and will provide a dee- per understanding of variations in plant diversity of the Triassic and Jurassic transition in southern China. Addi- tionally, it will provide terrestrial plant evidence for explorations in Jurassic palaeoecology, palaeoclimatology, and palaeogeography of southern China.     

The distribution of the oil derived from Cambrian source rocks in Lunnan area,the Tarim Basin,China

There are great differences in biomarks between Cambrian oil and Middle-Upper Ordovician oil. In this stuty, the authors analyzed 40 oils found in Lunnan area by GC-MS and calculated the content of Cambrian oil in the 40 oils according to the steroid indexes of typical oil mixture and match experiment. The results show that it is a general phenomenon in Ordovician reservoir that the oil derived from Cambrian source rock mixed with the oil derived from Middle-Upper Ordovician source rock in Lunnan area, the mixture degree of the two oils is lower in Carboniferous reservoir than in Ordovician reservoir, and the oils kept in Triassic reservoir have single source, Middle-Upper Ordovician source rock. The mixture oils mainly composed of Cambrian oil (>50%) distributed in Sangtamu fault zone, and the oils found in Lunnan fault zone are Middle-Upper Ordovician oil. This distribution of oils in Lunnan area is owing to that Lunnan fault zone is located in anticline axis part, Lunnan fault zone underwent serious erosion, and the oils from Cambrian source rock accumulated in Lunnan fault zone were degraded completely during Caledonian-Hercynian movement. But the Cambrian oil accumulated in Sangtamu fault zone was not degraded completely and some of them were left for the location of Sangtamu fault zone is lower than Lunnan fault zone. Later, the oil derived from Middle-Upper Ordovician source rock mixed with the remained Cambrian oil, and the mixture oil formed in Sangtamu fault zone.     

Sponge fossil assemblage from the Early Cambrian Hetang Formation in southern Anhui

Abundant well-preserved large articulated sponge fossils and isolated spicules have been reported from the Early Cambrian Hetang Formation, southern Anhui Province. This unique epifaunal fossil assemblage dominated by articulated sponge fossils is called the Xidi Sponge Fauna. The sponge fauna lived in a quiet oxygenic environment below the storm wave base. Bloom of phytoplankton and rapid sedimentation rate resulted in the deposition of the black shales. Sufficient food supply, lack of other competitors, abundant ecological niches, and demand for oxygen during early Cambrian were in favor of the diversification and evolution of large sponges in the Early Cambrian.     

Isotopic compositions of small shelly fossil Anabarites from Lower Cambrian in Yangtze Platform of South China: Implications for palaeocean temperature

Anabarites belong to small shelly fossils (SSF), which occur widely in the Lower Cambrian strata of Yangtze Platform in South China. They are phosphate shell in composition and represent the earliest stage of the Cambrian bioradiation of Bilateria, the so-called "Cambrian Explosion". In this study, we attempted to separate Anabarites fossils from Lower Cambrian dolostones, and we obtained samples of both the fossils (SSF) and the granular phosphates (GP). Isotopic analyses were performed on samples of SSF, GP, and matrix dolostone (DH-23). The results showed that the δ30Si values of the quartz filling in fossils celoms, and the siliceous materials in granular phosphates are -0.6‰ and -0.7‰, which is different from normal sedimentary siliceous rocks from the Lower Cambrian strata (0—0.7‰) as reported by Li et al., but is consistent with the data for siliceous rocks and cherts of submarine hydrothermal origin. It is likely that a later hydrothermal replacement could have taken place in the SSF-bearing sedimentary rocks. The oxygen isotope values of the phosphate of SSF and GP are 16.8‰ and 17.0‰, respectively. These are significantly higher than the Neoproterozoic phosphate ores (10.9‰—13.9‰) as reported by Ling et al., hence, late diagenesis and hydrothermal replacement may not have caused a significant change in the oxygen isotope compositions of the small shelly fossils, and the calculated temperatures (25.4—26.3℃) for palaeo-seawater using a SSF phosphate oxygen isotope thermometer are therefore considered here as the upper limit of seawater temperature in the Early Cambrian ocean of the Yangtze Platform.     

The distribution of the oil derived from Cambrian source rocks in Lunnan area, the Tarim Basin, China

There are great differences in biomarks between Cambrian oil and Middle-Upper Ordovician oil. In this stuty, the authors analyzed 40 oils found in Lunnan area by GC-MS and calculated the content of Cambrian oil in the 40 oils according to the steroid indexes of typical oil mixture and match experiment. The results show that it is a general phenomenon in Ordovician reservoir that the oil derived from Cambrian source rock mixed with the oil derived from Middle-Upper Ordovician source rock in Lunnan area, the mixture degree of the two oils is lower in Carboniferous reservoir than in Ordovician reservoir, and the oils kept in Triassic reservoir have single source, Middle-Upper Ordoviclan source rock. The mixture oils mainly composed of Cambrian oil （〉50%） distributed in Sangtamu fault zone, and the oils found in Lunnan fault zone are Middle-Upper Ordovician oil. This distribution of oils in Lunnan area is owing to that Lunnan fault zone is located in anticline axis part, Lunnan fault zone underwent serious erosion, and the oils from Cambrian source rock accumulated in Lunnan fault zone were degraded completely during Caledonian-Hercynian movement. But the Cambrian oil accumulated in Sangtamu fault zone was not degraded completely and some of them were left for the location of Sangtamu fault zone is lower than Lunnan fault zone. Later, the oil derived from Middle-Upper Ordovician source rock mixed with the remained Cambrian oil, and the mixture oil formed in Sangtamu fault zone.     

Early Cambrian eodiscoid trilobites of the Yangtze Platform and their stratigraphic implications

Analysis of the taxonomy and stratigraphic distribution of the Early Cambrian eodiscoid trilobites of the Yangtze Platform indicates that species of Tsunyidiscus and Hupeidiscus can be used for biostratigraphic correlation. T. aclis occurs only in the lower Qiongzhusian, T. armatus occurs in the lower and middle Qiongzhusian, while T. niutitangensis and T. tingi occur mainly in the middle and upper Qiongzhusian, with only T. tingi extending upward into the lower Canglangpuian. H. orientalis first appears in the upper Qiongzhusian, reaching peak abundance in the lower Canglangpuian and becoming extinct above the Drepanuroides Zone. Biostratigraphic and lithostratigraphic correlations indicate that the limestone in the lower part of the Mingxinsi Formation, the Upper Member of Jiumenchong Formation, and the upper part of the Middle Member of the Huangbailing Formation, can be correlated with each other as Hupediscus, an index fossil of the lower Canglangpuian, is abundant in all these units. The lower part of the Niutitang and Jiumenchong formations in eastern Guizhou, which mainly represent Qiongzhusian strata, can be correlated with the Lower Member of the Huangbailing Formation. The basal part of the Niutitang Formation, which may be equivalent to the Upper Meishucunian Shiyantou Formation in eastern Yunnan, is very condensed. Well-preserved sponge faunas and non-mineralized fossils in the lower part of the Niutitang and Hetang formations are not older than Qiongzhusian in age.     

Discovery of Late Carboniferous strata and their tectonic significance in the southern margin of the North China Block （Huoqiu and Gushi areas）

Late Carboniferous fossils （such as Boultonia？ sp., Tabulata, and spiriferoid specimens with smooth she/Is）, bioclastic material （such as crinoid stems and sponge fragments）, and Late Ordovician microfossils of the conodont Belodina have been discovered in the lower part of the strata typically referred to as the Neoproterozoic on the boundary of the provinces of Anhui and Henan in the southern margin of the North China Block. These findings prove that the strata contain macrofossils belonging to the Late Carboniferous, which belonged to a carbonate debris flow deposit that was formed under a carbonate slope environment. The conodont fossils might belong to a detrital deposit. Thus, it is possible to reset the stratigraphic sequences and tectonic attributes belonging to the North Huaiyang tectonic belt and limit the Shouxian fault to the boundary between the Dabie Orogen and North China Block.     

South China''s Gondwana connection in the Paleozoic: Paleomagnetic evidence

The reconstruction in which the South China Block (SCB) lies along the Great India-Australia region of Gondwana margin is tested by using existing Paleozoic paleomagnetic data.Under the proposed reconstruction, all six high quality paleopoles from the SCB between the Early Cambrian and late Early Devonian (～400 Ma) are in good agreement with coeval paleopoles from Gondwana.Thereafter, the apparent polar wander paths for the SCB and Gondwana diverge markedly.This indicates that the SCB had been part of Gondwana and the connection was intact from at least Early Cambrian until late Early Devonian, but they began to separate by late Middle Devonian (～375 Ma).     

Discovery of marine fossils in the upper part of the Permian Linxi Formation in Lopingian, Xingmeng area, China

Two important geological issues have a long history of debate in the Xingmeng area. The first concerns the final closure of the North China plate, Siberia plate and several intermediate massifs in the area, and the other con- cerns the folding and lifting of the Xingmeng Trough. Dis- agreements arise because of issues involving the tectonic- palaeogeographical environment of the Upper Permian deposits of the Linxi Formation. The Linxi Formation （Upper Permian） is generally considered to be either an exclusively continental deposit or separated into marine- terrigenous facies deposited during the Lower to Middle Linxi Period and continental deposits in the Upper Linxi Period. However, in this study, large numbers of bryozoan and sponge spicule fossils were discovered for this first time in the thick limestone layers and lenses of the upper part of the Linxi Formation found in the Guandi section of Linxi county in eastern Inner Mongolia. At the same time, abun- dant bryozoan fossils were also found in sedimentary tuff slices that were collected from the upper part of the Tao- huayingzi Formation from the Taohuayingzi section in Ar Horqin Banner, and abundant small connecting body crinoid stem fossils were found in the dark shale of the Yangjiagou Formation from the Yangjiagou section of Jiutai county, Jilin Province. These marine fossils provide the first evidence that the Xingmeng area was still a marine or mainly marine environment at the end of the late Permian. This not only provides conclusive evidence for the recognition of the above two major geological issues but also promotes chan- ges in the approach towards research, exploration and development of oil and gas, shale gas （oil）, and other mineral resources that are preserved in the late Permian layers of the Northeast-Xingmeng area.     

江西信丰县铁石口地区二叠—三叠纪牙形石动物群的发现及其地质意义

本文首次报道并描述了江西信丰县铁石口地区的二叠—三叠纪的牙形石动物群;根据牙形石和菊石、双壳类、腕足类,将“铁石口系”划分为三部分:下部(层1～10)、中部(层11～20)、上部(层21～23),它们分别相当于Griesbachian阶、Nammalian阶、Spathian阶。层2～8中发现了二叠纪型和三叠纪化石伴生的混生动物群。三叠系与二叠系之间可暂时以层1厚约3cm的黄白色粘土岩为界线,二系为整合关系。     

中国三叠纪含牙形刺地层

十年来,中国三叠纪牙形刺地层的研究取得了很大的成绩。1.三叠纪含牙形刺地层主要分布在中国南方,尤其在昆仑-秦岭一线以南,此地层发育程度由西向东逐渐减弱,例如:西部珠峰地区分布在整个三叠系地层中,向东到下扬子地区,主要分布在下三叠统中。2.中国三叠纪牙形刺很丰富,已发现39属,230种,可划分成24个带。3.在奥伦尼阶,我国牙形刺根据生态可划分为两种类型:(1)盆地型(珠峰类型),(2)台地型(湖北利川类型)。     

四川马角坝地区飞仙关组的双壳类动物群

文章简述了四川江油马角坝地区下三叠统飞仙关组中的双壳类化石组合特征，描述了１新种（Ｃｌａｒａｉａｊｉａｎｇｙｏｕｅｎｓｉｓ）和１新亚种（Ｃｌａｒａｉａｓｏｎｇｐａｎｅｎｓｉｓｍａｇｎｕｓ），划分出两个双壳类化石带（Ｐｓｅｕ－ｄｏｃｌａｒａｉａｗａｎｇｉ带和Ｅｕｍｏｒｐｈｏｔｉｓｍｕｌｔｉｆｏｒｍｉｓ－Ｃｌａｒａｉａａｕｒｉｔａ－Ｃｌａｒａｉａｓｔａｃｈｅｉ带），刊出了主要化石图版     

四川盆地二叠系牙形石研究及其油气意义

二叠系以海相碳酸盐岩地层为主,是四川盆地的重要产气层之一。作者对33条剖面进行了系统的工作,在取得丰富牙形石资料的基础上,对该区二叠系的地层划分与对比,二叠系至三叠系底部的Neogondolella和Anchignathodus属的演化系列,沉积相与牙形石的关系,和根据上二叠统牙形石色变判断上三叠统油气成熟度指标等进行研究     

黔西南三叠系永宁镇组牙形石研究—兼论下,中三叠统界线

本文首次系统描述了贵州贞丰县龙场、关岭县永宁镇的永宁镇组牙形石5属12种;在永宁镇组中识别出4个牙形石组合带(层)(由下而上):1. Pachycladina obliqua-Parachirognathus delicatulus带,2. Neospathodus homeri-Neospathodus triangularis.带,3. Neogondolella cf. jubata-Neospathodus timorensis带,4. Neogondolella navicula navicula-Neogondolella constricta层;首次将下、中三叠统的界线置于 Neogondolella navicula navicula-Neogondolella constricta层之底,即永宁镇组第4段之底。两统之间为整合接触。     

Advance in the study of the Lower Triassic conodonts at Meishan Section, Changxing, Zhejiang Province

Meishan Section in Changxing County of Zhejiang Province is one of the four candidates of the global stratotype section and point (GSSP) of the Permian and Triassic boundary (PTB), and currently the conodonts have been widely accepted as the index fossils to define the Permian and Triassic boundary. The previous studies on the Lower Triassic conodonts at Meishan Section are summarized and the recent discovery of the Lower Triassic conodonts there is reported. The recognized data from the section indicate that Meishan is the best selection of the GSSP of PTB.     

中国的三叠纪海生爬行动物化石及其层位

对中国三叠纪海生爬行动物化石及其产出层位、产地进行了较为系统的分析研究和总结,划分出4个相关的海生爬行动物群:早三叠世南漳海生爬行动物群、中三叠世兴义海生爬行动物群、晚三叠世关岭海生爬行动物群、晚三叠世定日海生爬行动物群.进一步的研究表明,中国三叠纪海生爬行动物化石数量比较丰富,种类多样;特别是贵州关岭地区三叠纪海生化石数量多、保存完整,基本上为原地埋藏,实属国内外同期地层之罕见.中国三叠纪海生爬行动物化石地史分布从早三叠世奥伦尼克期到晚三叠世诺利期都有分布;地理分布主要分布于古东特提斯海域,具有明显的区域性.     

渭北地区石炭纪牙形刺初步研究

本文对渭北地区石炭纪地层中采集的牙形刺进行了研究。经鉴定,共获得牙形刺6个属,8个种和6个未定种。其中中石炭统本溪组以Streptognathodus cf.parvus和?Idiognathodus corrugatus为代表;上石炭统太原组下部以Streptognathodus gracilis为代表;中部以S.oppletus,S.elegantulus和Idiognathodus delicatus为代表;上部经与其它地区同时期的牙形刺相比,缺失了以S.elongatus和S.wabaunsensis为代表的矛形刺动物群。