Reexamination of Radiolarian Biostratigraphy in Permian in Pelagic Chert Sequences at Dachongling Section, South China

Permian radiolarian biostratigraphy was reexamined in the bedded chert section in Qinzhou area of southeast Guangxi Zhuang Autonomous Region, South China. On the basis of the analyses of characteristic radiolarian composition, six radiolarian zones are recognized, namely, Pseudoalbaillella longtanensis Zone, Pseudoalbaillella globosa Zone, Follicucullus monacanthus Zone, Follicucullus scholasticus Zone, Follicucullus charveti Zone and Neoalbaillella ornithoformis Zone, in ascending order. Correlation of these radiolarian zones with those in Japan is presented. The Neoalbaillella ornithoformis Zone was firstly discovered in Dachongling Section, which may indicate that pelagic chert of the late Permian existed there, according to the co-occurring conodonts.     

湖北宜昌黄花场中/下奥陶统界线附近几丁虫组合及其地层学意义

对宜昌黄花场大湾组下段牙形石 Oepikodus evae带至 Baltoniodus triangularis带系统采集与分析几丁虫样品 ,共发现几丁虫 6属 12种 ,其中包括 1个相似种、1个未定种 ,它们是 Conochitina raymondii,C.ordinaria,C.primitiva,C.langei,C.brevis,C.poumoti,C.decipiens,Belonechitina cf.micracantha,L agenochitina esthoni-ca,L.sp.,Eremochitina baculata和 Cyathochitina dispar等。根据上述几丁虫的地质和地理分布特征 ,自下而上可划分为 Conochitina langei带和 Eremochitina baculata带 ,讨论并指出了他们与相关笔石、牙形石生物带的关系     

西藏色龙西山色龙群的时代及二叠系与三叠系的界线

<正> 色龙群于1964年由希夏邦马峰登山队科学考察队(1982)命名,层型剖面在聂拉木县色龙村西北约1km的小山上,时代为二叠纪。穆恩之等(1973)认为色龙群的时代属早二叠世晚期。章炳高(1974)、吴望始(1975)、张守信、金玉玕(1976),王玉净、穆西南(1984)对色龙群的时代有类似的看法,均未提及它包含有长兴期地层的存在。饶荣标等(1985)将色龙群分为两组,上部为扒嘎组,下部为门多组。在色龙西山剖面,扒嘎组为生物碎屑灰岩,厚4.15m,含Gertholites curvatus,Thamnopora densa,Pseudofavosites irregularis,Trachypora sp.,Sinkiangopora sp.,时代属晚二叠世,与上覆下三叠统土隆组为整合接触。     

鄂西地区上二叠统的牙形石及其分带意义

湖北恩施天桥剖面发育有完好的二叠系大隆组下段硅质岩层。对其下伏吴家坪组灰岩及上覆大隆组上段灰岩中牙形石的研究表明,吴家坪组灰岩自下而上可分为Clarkina postbitteri postbitteri带、Clarkina dukouensis带、Clarkina asymmetrica带以及Clarkina guangyuanensis—Clarkina transcaucasica带,属吴家坪阶中下部牙形石带;大隆组上段灰岩可划分出两个牙形石带,即Clarkina subcarinata—Clarkina wangi带和Clarkina changxingensis changxingensis—Clarkina deflecta带,为长兴阶底部牙形石带。认为鄂西地区大隆组下段硅质岩的时代应归属于二叠纪吴家坪中期至长兴早期。     

滇东下寒武统含磷岩系底部火山喷发事件沉积及其意义

云南曲靖德泽剖面下寒武统梅树村组待补段底和晋宁梅树村剖面小歪头山段底粘土岩层的岩石、矿物和元素地球化学特征表明，这些粘土岩层是由酸性火山灰蚀变而成的变斑脱岩。它们是同期火山喷发事件沉积的标志，也是滇东地区下寒武统梅树村组底界等时对比的标志层。根据这个标志层以及小歪头山段和待补段沉积序列的对比，梅树村剖面小歪头山段仅相当于小江断裂以东地区的待补段下部白云岩层，缺失上部硅质岩层，因而它不能代表滇东地区下寒武统梅树村组下段的沉积序列。     

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.     

鄂东伍家冲剖面乐平世牙形石生物地层及大隆组的时代

大隆组是华南地区乐平世一种重要的较深水沉积.为进一步探讨大隆组沉积的时空分布,选择对鄂东伍家冲剖面吴家坪组和大隆组重点进行了牙形石生物地层研究,此次研究共鉴定出牙形石1属5种,均为Clarkina,并由老到新识别出4个牙形石带:C.guangyuanensis带、C.transcaucasica带、C.orientalis带及C.wangi带.根据牙形石C.wangi的首现,将伍家冲剖面的吴家坪阶-长兴阶界线(Wuchiapingian-Changhsingian boundary,简称WCB)置于第18层底部.根据菊石Ophiceras的首现将伍家冲剖面的二叠系-三叠系界线(Permian-Triassic boundary,简称PTB)置于第20层顶部,仅高于WCB界线0.72 m.牙形石生物地层指示伍家冲剖面大隆组的主体为吴家坪期沉积产物.数个长兴期牙形石带的缺失和极短的长兴阶表明,该剖面长兴阶中上部可能因沉积间断存在缺失.      

滇西南耿马地区泥盆纪牙形石的发现

在耿马东部大龙塘等地的硅质岩系中新发现大量牙形石，可建立两个牙形石带：Palmatolepis gigas带、Palmatolepis triangularis带。此套含牙形石硅质岩系的时代属于晚泥盆世弗拉斯阶—法门阶，对比为曼信组。     

Early Eocene Radiolarian Fauna from the Sangdanlin, Southern Tibet: Constraints on the Timing of Initial India-Asia Collision

This is a new report on the early Eocene radiolarian fauna from the Sangdanlin section in the Gyirong region, along the southern margin of the Yarlung Zangbo Suture Zone. The Sangdanlin section measured in this study is divided into three lithostratigraphic units from bottom to top: the Zongzhuo, Sangdanlin, and Zheya formations. Abundant radiolarian fossils were obtained from the Sangdanlin section and 54 species of 30 genera were identified and assigned as follows: Cryptamphorella conara-C. macropora the late Cretaceous Zone and Amphisphaera coronate, Buryella tetradica-Bekoma campechensis, and B.bidartensis-B. divaricata the Paleocene-early Eocene Interval Zones. The Paleocene–early Eocene radiolarian zones are comparable to the radiolarian zones RP4-RP8 in New Zealand. Based on the data of radiolaria and lithofacies, it is suggested that the Zongzhuo Formation should be deposited along the base of the north-facing, continental slope of the Greater Indian continental margin, and the Sangdanlin Formation should be a deep marine, sedimentary sequence located in a foreland basin. The early Eocene radiolarian fauna in the Sangdanlin Formation constrains the initial age of the India-Asia collision to no later than 53.6 Ma.     

广东曲仁二叠纪含煤地层的牙形刺及地层划分

<正> 广东的二叠纪含煤地层的时代和层位归属一直是个争论的问题,我们重点选择了广东曲(江)仁(化)二叠纪煤田(图1),进行牙形刺的研究。在龙潭组中部余煤段、海相段,上部东煤段和长兴组内均发现了牙形刺,在王成源和王志浩的指导下进行了鉴定,有7属14种和2个未定种,以Neogondolella为主,计10种,并有Anchignathodus,Enantiognathus,Lonchodina,Prioniodella,Neohindeodella,Xaniognathus等,     

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。     

贵州紫云四大寨早三叠世地层初步研究

贵州紫云四大寨剖面下三叠统发育较齐全,化石较丰富。在此剖面上发现了大量牙形石、双壳类、菊石等生物化石,其中牙形石在该剖面上为首次发现,并识别出了早三叠世Neospathodusdieneri带、Neospathoduscrista-galli带、Neospathoduswaageni带和Neospathodushomeri-Neospathodustriangularis带的重要牙形石分子或带化石,可与国际同期地层中相应的牙形石化石带进行较好的对比;同时还发现了Claraiagriesbachi-C.concentrica组合和Claraiastachei-Claraiaaurita组合带的双壳类代表性分子。通过对这些化石综合分析,大致拟定了本剖面下三叠统格里斯巴赫亚阶(Griesbachian)、亭纳尔亚阶(Dienerian)、斯密斯亚阶(Smithian)和斯派斯亚阶(Spathian)的年代地层单位界线。     

贵州西南部“法郎组”牙形石及其时代

根据近年牙形石研究,在“法郎组”中从下而上识别了３个牙形石带：１、Ｎｅｏｇｏｎｄｏｌｅｌｌａｐｏｌｙｇｎａｔｈｉｆｏｒｍｉｓ－Ｎｅｏｇｏｎｄｏｌｅｌｌａｍａａｎｔａｎｇｅｎｓｉｓ组合带;２、Ｎｅｏｇｏｎｄｏｌｅｌｌａｐｏｌｙｇｎａｔｉｆｏｒｍｉｓ－Ｎ－ｅｏｇｏｎｄｏｌｅｌｌａｔａｄｐｏｌｅ组合带;３、Ｎｅｏｇｏｎｄｏｌｅｌｌａｐｏｌｙｇｎａｔｉｆｏｒｍｉｓ带。根据牙形石Ｎ．ｅｘｃｅｌｓａ谱系演化、牙形石发展事件、牙形石分带及其与国内外的牙形石带对比,论证了“法郎组”的时代,“法郎组”可解体为瓦窑组和竹杆坡组,全属晚三叠世卡尼期,而不是拉丁期。     

晚白垩世中国东南沿岸山系与中南地区的沙漠和盐湖化

晚白垩世在中国东南沿古太平洋西岸地区形成了一条巨大的沿岸山系，其山峰高度在３５００—４０００ｍ之间，东西宽度近５００ｋｍ，挡住了东来的暖湿气流，使中南地区云梦泽内陆水域的广大平原和丘陵地变成了一个热带—亚热带干旱、炎热的半沙漠和盐湖地区，这一古地理和古气候格局一直持续到早第三纪末才开始改变。     

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     

Conodonts from the Sesong Slate and Hwajeol Formation (Guzhangian to Furongian) in the Taebaeksan Basin, Korea

Abundant conodont elements have been recovered from the Hwajeol Formation, to allow five zones to be erected: Proconodontus, Eoconodontus notchpeakensis, Cambrooistodus minutus, Cordylodus proavus, and Fryxellodontus inornatus-Monocostodus sevierensis-Semiacontiodus lavadamensis zones, in ascending order. More confident biozones are recognized in the Sesong Slate and lower Hwajeol Formation in the Makgol section, a part of the southern limb of the Baekunsan syncline, Taebaeksan Basin, Korea, especially focusing on the conodont biostratigraphic boundary of two units, and the subdivision potential of the previous "Proconodontus Zone", lowermost biozone of the Hwajeol Formation. Similarly, only a few conodont elements recovered from upper 14.5 m interval, namely the Furongian portion of the Sesong Slate, in the Makgol section did not allow erection of a biozone. Nevertheless, this part of the unit plus the basal 2.5 m interval of the Hwajeol Formation is characterized by the occurrence of Prooneotodus rotundatus(Druce and Jones), Teridontus nakamurai(Nogami), Phakelodus elongatus(An) and Phakelodus tenuis Müller. This interval marks the early Furongian "Prooneotodus rotundatus Zone". The rest of the measured section yielded relatively abundant conodonts, so three conodont biozones are proposed, based on the successive appearance of key species: Proconodontus tenuiserratus, Proconodontus posterocostatus, and Proconodontus muelleri zones, in ascending order, and thus allowing subdivision of the previous "Proconodontus Zone". The four conodont biozones are correlated with the relevant biozones of North and South China, and North America.     

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.     

浙江桐庐县刘家奥陶纪剖面生物地层学初步研究

新发现的浙江桐庐刘家剖面位于马金一乌镇断裂与球川一萧山断裂之间,是浙西北地区以碎屑岩沉积为主的代表性奥陶纪地层剖面。根据所获得的宁国组和胡乐组的笔石化石,初步建立了该层段的笔石生物地层序列,自下而上包括Tetragraptusapproximatus带、Corymbograptusdeflexus带、Azygograp...