北美西部内陆海盆Niobrara组的钙质超微化石及其环境意义——Ⅱ：古环境研究

沉积于北美西部白垩纪内陆海盆的Niobrara组，是一套以白垩，白垩质灰岩，以及钙质页岩为主的海相沉积，其中自垩的主要组分为颗石藻及其它钙质超微化石。通过对Kansas州西部和South Dakota州东部四条剖面中Niobrara组的岩性，沉积物厚度，及钙质超微化石的研究，证明北美西部内陆海盆的沉积环境及水体温度在Niobrara组沉积时期因地而异。在Niobrara组沉积初期，海盆内的水体温度为北冷南暖，其后，至少在位于Kansas西部海域的海水温度呈与时逐渐降低趋势。钙质超微化石有关属种在盆地内的分布差异，进一步说明海水变冷的直接原因源自北极海域水体的缓慢南浸。     

南海北部第三纪钙质超微化石生物地层学研究

本文根据40口钻井剖面的钙质超微化石分析和研究成果,将南海北部海相第三系,划分出上渐新统至上新统18个超微化石带和始新统1个未命名组合。始新统未命名组合仅见于珠江口盆地东北缘。上渐新统至上新统18个超微化石带为连续沉积,但各带的发育程度不尽相同。其中相当于E.Martini(1971)划分的NN4—NN5带,NN11带和NN13—NN15带发育良好,横向稳定,分布广。它们是南海北部上第三系划分和对比的重要标志。结合部分有孔虫分带和岩性资料,探讨了全区海相第三系的沉积特征及沉积间断分布发育情况。文中还讨论了下、上第三系,第三系与第四系的超微化石划分标志以及再沉积超微化石的特点和地质意义。     

甘肃合作早三叠世钙质超微化石的发现

在甘肃合作地区早三叠世地层中发现了钙质超微化石，共属３种，共文描述了２个新属３个新种。它们位于斜坡脚－盆地的深海沉积环境中，与早三叠世早期双壳类Ｃｌａｒａｉａ共生，其下部有具早三叠世面貌的孢粉组合。经能谱成成分分析，这些化石为钙质。这些钙质微化石的发现使钙质超微化石的时代分布的可靠记录延至早三叠世。为今后中生代地层的划分对比及钙质超微化石的演化研究提供了较好的资料。文中依据所发现的钙质超微化石对沉     

塔里木盆地西部晚白垩世钙质超微化石

本文分析研究了塔里木盆地西部晚白垩世钙质超微化石,划分出Quadrumgartneri,Eprolithus floralis两个组合,从一个新的角度为探讨库克拜组和乌依塔克组的地层时代及其沉积环境提供有关的论据.     

西藏南部早第三纪钙质超微化石及东特提斯在西藏境内的封闭时限

研究了西藏南部定日地区曲密巴剖面早第三纪遮普惹组上页岩段的钙质超微化石 ,自下而上划分出 3个超微化石组合 :N annotetrina fulgens-Chiasmolithusgigas组合 ;Discoaster bifax-Chiasmolithussolitus组合及 Sphenolithuspseudoradians-Reticulofenestra bisecta组合 ,确定了上述3组合可与 Martini( 1 971 )超微化石分带的 NP1 5、NP1 6及 NP1 7带对比。还确认了第三超微化石组合的层位是西藏地区海相第三纪目前已知的最高层位 ,它的时代应为中始新世晚期 ,即属 Bartonian期。根据超微化石属种的时限分布的分析 ,东特提斯在西藏境内的封闭时间大约在3 8Ma左右 ,即至该时期 ,海水完全退出青藏高原 ,印度板块和欧亚板块完全拼合 ,青藏高原开始大幅度的隆升。     

渤海湾盆地早第三纪钙质超微化石的发现及其意义

近年来,石油部石油勘探开发科学研究院在渤海湾盆地早第三纪沙河街组中首次发现钙质超微化石.这不仅为该盆地遭受海侵提供佐证,也为研究中国东部的古气候、古地理提供有意义的信息.经鉴定,辽河断陷西部凹陷沙河街组一段下部的钙质超微化石是Retjculofenestra sp.、Co-ccoljthus sp .、Cyclococcocithi-thina sp.东濮凹陷北部地区沙河街组一段下部及沙河街组三段中下部的钙质超微化石是:Reticu-lofenestra sp.、Coccolithus sp.、Coronocyclu(?)?sp..     

藏南江孜地区早白垩世甲不拉组钙质超微化石的特征及其地层意义

藏南江孜一带的侏罗纪—白垩纪海相地层被划分为维美组和甲不拉组。通过偏光显微镜和扫描电镜观察和分析,发现甲不拉组黑色页岩中含有保存较为完好的钙质超微化石。研究区的生物丰度和分异度偏低,经鉴定以椭圆球石科(Ellip-sagelosphaeraceae)生物群为主,数量相对丰富,但属种比较单调。超微化石指示甲不拉组为早白垩世沉积的产物。结合菊石和双壳类化石,认为甲不拉组地层时代属于早白垩世贝利阿斯期至凡兰吟期(Berriasian-Valanginian)。这一发现标志着西藏特提斯东部早白垩世地层中钙质超微化石的存在。甲不拉组早白垩世钙质超微化石的发现,为该地区海相地层的时代划分、对比提供了新的资料,也为寻找海相侏罗纪—白垩纪地层界线指示了目标。     

藏南江孜地区早白垩世甲不拉组钙质超微化石的特征及其地层意义

藏南江孜一带的侏罗纪—白垩纪海相地层被划分为维美组和甲不拉组。通过偏光显微镜和扫描电镜观察和分析,发现甲不拉组黑色页岩中含有保存较为完好的钙质超微化石。研究区的生物丰度和分异度偏低,经鉴定以椭圆球石科（Ellip-sagelosphaeraceae）生物群为主,数量相对丰富,但属种比较单调。超微化石指示甲不拉组为早白垩世沉积的产物。结合菊石和双壳类化石,认为甲不拉组地层时代属于早白垩世贝利阿斯期至凡兰吟期（Berriasian-Valanginian）。这一发现标志着西藏特提斯东部早白垩世地层中钙质超微化石的存在。甲不拉组早白垩世钙质超微化石的发现,为该地区海相地层的时代划分、对比提供了新的资料,也为寻找海相侏罗纪—白垩纪地层界线指示了目标。     

松辽盆地海侵事件——松科1井钙质超微化石新证据

松辽盆地作为中国最大的陆相含油气盆地,是否发生过海水侵入一直存在争议,化石能为该科学问题提供直接解释。在松科1井嫩江组一、二段发现了少量的钙质超微化石,初步鉴定出Calculites obscurus,Calculites ovalis,Quadrum sp.,Micula sp.等属种。上述钙质超微化石广泛分布于晚白垩世海相地层中,通过与国际标准海相化石的对比,将嫩江组一段中、下部的时代限定为Turonian晚期—Maastrichtian期。松辽盆地嫩江组一、二段下部的钙质超微化石保存总体一般,有一定的多样性,具有海相钙质超微化石的特征。松科1井钙质超微化石的分布、古生态及其与有孔虫化石的对应关系表明,松辽盆地嫩江组一段中-下部、二段下部沉积期湖泊水域广阔,全球海平面较高,间歇性的海水侵入事件导致西北太平洋中的钙质超微浮游生物和有孔虫等海洋生物被带入松辽盆地。     

我国咸化湖泊沉积中钙质超微化石特征及其地质意义

对我国西北和东北（内蒙古东部）36个地点的新生代-现代陆相咸化湖泊沉积中的433块标本进行了采样分析，在其中15个地点38块标本中发现钙质超微化石10个属：Coccolithus, Reticulofenestra, Cyclicargolithus,Quadrum, Discoaster, Gephyrocapsa, Calcidiscus, Umbilicasphaera,Cotonocyclus, Watznaueria等，多数为原地沉积，也有一部分属于再沉积来源。由此可见，不能笼统地把所有钙质超微化石的发现都当作海相或海侵的证据。陆相咸化湖泊沉积中钙质超微化石的特点是：丰度低，数量稀少；属种分异度低；常与陆相喜盐水生生物共生。第四系和现代陆相咸化湖泊沉积中发现的钙质超微化石属种往往是海相第四系或现代海洋中常见类型。在青海柴达木盆地七个泉构造七心1井中-上始新统下干柴沟组上段岩心中，发现Reticulofenestra bisecta。这是海相中始新世-渐新世沉积中标志化石。看来，利用钙质超微化石进行海、陆相地层对比探索已取得一定进展，但离“统”一级的地层对比还有很大距离。     

Marine connections in North America during the late Maastrichtian: palaeogeographic and palaeobiogeographic significance ofJeletzkytes nebrascensisZone cephalopod fauna from the Elk Butte Member of the Pierre Shale, SE South Dakota and NE Nebraska

The Elk Butte Member of the Pierre Shale of southeast South Dakota and northeast Nebraska yields a late Maastrichtian cephalopod fauna of nautiloids, belemnites and ammonites of theFeletzkytes nebrascensisZone, best known from the near-shore facies of the Fox Hills Formation. ThenebrascensisZone is the highest distinct marine assemblage that can be recognised in the Western Interior, although ammonites occur as rarities high in the Lance Formation in Wyoming. Elements of the fauna occur in the Gulf Coast and Atlantic Seaboard, and extend into the highest Maastrichtian nannofossil Subzone CC26b, ofMicula prinsii, in Texas. These occurrences point to the existence of a southerly marine route for migration into and out of the northern Interior during the late late Maastrichtian. An analysis of Maastrichtian ammonite occurrences in West Greenland reveals no evidence for a marine link to the western Interior at this time, but rather indicates an open marine link to the North Atlantic region.The presence of upper upper Maastrichtian Pierre Shale in southeast South Dakota and northeast Nebraska, deposited in water depths that are conservatively estimated at 100-200 m, suggests that marine conditions (evidence for which has been removed by post-Cretceous erosion) may have extended well to the north of the shoreline position indicated in recent palaeogeographic reconstructions.     

Late Cretaceous stratigraphy,sediments and structure: Gems of the Dorset and East Devon Coast World Heritage Site (Jurassic Coast), England

Extraordinary, long-distance litho-marker beds such as the Lewes and Shoreham Tubular Flints and associated marl seams and fossils, recognised in cliff exposures and cliff-fall boulders, are keys to unlocking the stratigraphy and tectonic structures in the Late Cretaceous of the Dorset and East Devon Coast World Heritage Site (Jurassic Coast). Durdle Cove is a special gem exposing the Lewes and Seaford Chalk stratigraphy where new marker beds are identified and sediments and tectonic structures provide clues to timing of movements that produced a Late Cretaceous pericline which grew into a Miocene monocline along the line of the underlying Purbeck Reverse Fault. During ‘inversion’ along this fault some Late Cretaceous Chalk formations were in part or completely ‘lost’ (e.g. Middle Turonian New Pit Chalk Formation) and others were condensed (e.g. Late Santonian and Early Campanian Newhaven Chalk Formation). Excavation of the A354 road cutting at the Lower Bincombe Farm, has greatly added to the stratigraphical records of Late Cretaceous fossils in South Dorset, especially Coniacian and Early Campanian inoceramid bivalves and the various stratigraphically specific forms of the Late Santonian to Early Campanian echinoid fossil Echinocorys scutata spp. not recorded before in this coastline. The very large bivalve fossil Platyceramus sp. provides clues to chalk sea-floor environments.     

Biostratigraphical correlations of the calcareous nannofossil Marthasterites furcatus in the Bohemian Cretaceous Basin and Outer Flysch Carpathians,Czech Republic

The first occurrence (FO) of Marthasterites furcatus was correlated with the FOs of other nannofossils, inoceramid bivalves and foraminifers in the Bohemian Cretaceous Basin and Outer Flysch Carpathians. The correlation showed that the FO of M. furcatus was diachronous, becoming younger from east to west. In the Silesian Unit it appears in the lower Turonian in association with Eprolithus moratus (UC6b nannofossil Zone). In the Pavlovské vrchy klippes it appears in the upper middle Turonian together with Lithastrinus septenarius (UC9 Zone). In the Bohemian Cretaceous Basin, the FO of M. furcatus was observed in the lower upper Turonian just above the FO of Liliasterites angularis. The presence of M. furcatus in Turonian strata is scarce and discontinuous up to its sudden quantitative increase (represented by 5–27% in assemblages) below the FO of the inoceramid bivalve species Cremnoceramus waltersdorfensis and C. deformis erectus in the Turonian–Coniacian boundary interval. The top of the M. furcatus acme was recorded below the FO of Micula staurophora. The second quantitative rise of M. furcatus (12% in assemblage) was found in the lower lower Campanian of the Pavlovské vrchy klippes above the FO of Broinsonia parca parca in the UC14a Zone and the last occurrence of the planktonic foraminifer Whiteinella baltica. Above this second acme M. furcatus disappears. The significantly earlier appearance of M. furcatus in the Silesian Basin may be connected with a southeast-heading surface current from the North European epicontinental sea where the species appeared in the early Turonian too.     

Calcareous nannofossils from the Gurpi Formation (Lower Santonian-Maastrichtian), faulted Zagros range,western Shiraz,Iran

The Gurpi section in western Shiraz, faulted Zagros range of southwestern Iran, contains one of the most complete Early Santonian to Late Maastrichtian sequences. The lack of a good fundamental paleontological study is a strong motivation for investigating calcareous nannofossils in southwestern Iran. The Gurpi Formation is mainly made up of grey shale. As a result of this study, 23 genera and 47 species of nannofossils have been identified for the first time. This confirms the existence of biozones CC14–CC26, which suggests the age of Early Santonian to Late Maastrichtian. All Early Santonian to Late Maastrichtian calcareous nannofossil biozones from CC14 (equivalent to the Micula decussate Zone) to CC26 (equivalent to the Nephrolithus frequens Zone) are discussed. Additionally, the zonal subdivision of this section based on calcareous nannofossils, is correlated with planktonic foraminiferal zones (Dicarinella asymetrica Zone to Abathomphalus mayaroensis Zone). We can also learn about the predominant conditions of the studied sedimentary basin that was in fact a part of the Neotethys basin with the existence of index species of calcareous nannofossils indicating a warm climate and high depths of the basin in low latitudes.     

Didactyl raptor tracks from the Cretaceous,Plainview Sandstone at Dinosaur Ridge

Two natural casts of two-toed (didactyl) tracks from the Cretaceous (Albian) Plainview Sandstone (Plainview Member) of the South Platte Formation (Dakota Group) at Dinosaur Ridge, Colorado are attributed to deinonychosaurian theropod dinosaurs and placed in the ichnogenus Dromaeosauripus. This is both the first report of tracks from this unit in the Dinosaur Ridge area and the first report of deinonychosaurian tracks from Colorado. It is also only the third report of this track type from North America. The rarity of tracks from the Albian-aged, Plainview Sandstone (Dakota Group Sequence 2) contrasts with their abundance in the upper (Cenomanian) part of the overlying South Platte Formation (Dakota Group Sequence 3), which has yielded more than 120 sites mostly in Colorado, giving rise to the “Dinosaur Freeway” concept. As no deinonychosaurid tracks are known from the sequence 3 part of the South Platte Formation, despite the large vertebrate and invertebrate ichnological database available, it is evident that the sparse vertebrate ichnofauna from the Plainview Member (Sequence 2) is inherently different. This striking difference in both track abundance and track type reflects differences in both age and depositional environment. Based on the Albian age, and track type, the Plainview tracks invite comparison with the ichnofaunas of the Cedar Mountain Formation and not with those well-known from the upper part of the South Platte Formation known as the Dinosaur Freeway.     

黑龙江省东部中侏罗世至早白垩世沟鞭藻组合序列

对近二十年来黑龙江省东部海相侏罗纪—白垩纪沟鞭藻地层资料进行了综合研究 ,首次为该地区建立起侏罗纪—白垩纪沟鞭藻地层序列 ,主要包含 7个组合带 (含 3个高峰带 ) ,其中绥滨地区 Callovian— Valanginian期有 4个带 ;鸡西盆地早白垩世也有 4个带 (其中包括与绥滨地区早白垩世早期同时异相的一个 )。它们自下而上为 :1)绥滨组的 Pareodinia ceratophora- N annoceratopsispellucida组合带 ;　 2 )东荣组下部的 Gonyaulacysta jurassica组合带 (高峰带 ) ;　 3)东荣组上部的 Amphorula delicata组合带 ;　 4 )东荣组最上部的海相 Oligosphaeridium pul-cherrimum组合带 (高峰带 )或鸡西盆地滴道组的微咸水—半咸水的 Vesperopsis didaoensis- L agenorhytis granoru-gosa组合带 ,两者为同时异相关系 ;　 5 )城子河组下部海相层的 Odontochitina operculata- Muderongia tetracantha组合带 (该带可进一步划分出 2个亚组合带 ) ;　 6 )城子河组上部海相层的 Canningia reticulata组合带 ;　 7)穆棱组下段的 Cribroperidinium ?parorthoceras组合带 (高峰带 )。     

High-resolution calcareous nannofossil biostratigraphy of the Santonian/Campanian Stage boundary,Western Interior Basin,USA

The base of the Campanian Stage does not have a ratified Global Stratotype Section and Point (GSSP); however, several potential boundary markers have been proposed including the base of the Scaphites leei III ammonite Zone and the base of the paleomagnetic Chron C33r. Calcareous nannofossil assemblages from the Smoky Hill Member of the Niobrara Formation in the central Western Interior Seaway, USA were analyzed from two localities to determine relevant biohorizons and their relationships to these potential boundary markers. In a previous study, the Aristocrat Angus 12-8 core (Colorado) was astrochronologically dated and constrained using macrofossil zonations and radiometric ages. The Smoky Hill Member type area (Kansas) provides an expanded interval with good to excellent nannofossil preservation.Five biohorizons are useful for recognition of the Santonian/Campanian transition within the Smoky Hill Member type area, and three are useful in the Aristocrat Angus 12-8 core. The first occurrences (FOs) of Aspidolithus parcus parcus and Aspidolithus parcus constrictus, as well as the last occurrences (LOs) of Zeugrhabdotus moulladei, Helicolithus trabeculatus specimens larger than 7 μm, and Zeugrhabdotus biperforatus are in close stratigraphic proximity to the base of the Scaphites leei III Zone and the base of Chron C33r.     

Calcareous nannofossils from chalky limestone of upper Abderaz Formation and lower part of Abtalkh Formation in the Kopet-Dogh range NE Iran

For the first time, the calcareous nannofossils of the chalky limestone of upper Abderaz Formation and lower part of Abtalkh Formation have been studied. In this study, 83 nannoplanktonic species of 45 genera were identified and presented. A biostratigraphic study of calcareous nannofossils from this section has allowed the recognition of five calcareous nannofossil biozones of Sissingh (Geol Mijnbouw 56:37–65, 1977) CC17–CC21. On the obtained calcareous nannofossils, the age of this section is Late Santonian/Early Campanian–Early Late Campanian.     

Discovery of the largest pterosaur from South America

A giant humerus (450 mm total length) belonging to one of the largest pterosaur recorded in South America is described. The specimen (UNCUYO-LD 350) was discovered in the Upper Cretaceous (upper Coniacian – lower Santonian) Plottier Formation of the Mendoza Province, northern Neuquén Basin, Argentina. It was found associated with a smaller pterosaur specimen represented by around thirty postcranial bones. The specimen is assigned to Tapejaroidea and show characters of both Tapejaridae and Azhdarchidae. Based on comparisions with other Azdharchidae species, a wingspan of 9.1 m is estimated for UNCUYO-LD 350, showing that giant pterosaurs were present in South America during the Upper Cretaceous.