山东滩海地区下第三系生物地层与沉积环境初探

<正> 山东滩海地区位于胜利油气区东部沿海一带,自北向南依次为埕北凹陷、埕子口凸起及沾化凹陷东部的桩西、五号桩和孤东等地(图1)。多年来的石油地质勘探表明本区下第三系构造单元复杂,沉积类型多样,地层的超覆、剥失现象普遍,为地层油气藏     

西藏阿里地区的腹足类化石

采自西藏阿里地区五县市几个层位的腹足类化石分属早奥陶世、早石炭世、早二叠世、早白垩世(多数)、晚白垩世(少数)及第三纪等时限;共计31种(包括12个新种、3个相似种、8个未定种),归入26属(包括1新属),分属14科。它们的地理分布及与它区的对比也略予论述。     

Middle Miocene to Pleistocene radiolarian biostratigraphy in the Northwest Pacific Ocean, ODP Leg 186

Abstract The Upper Cenozoic sedimentary sequences drilled at Sites 1150 and 1151, Ocean Drilling Program Leg 186, enabled establishment of radiolarian zonation and calibration of the age of bioevents in the forearc area of the northern Japan Islands. The sequences were divided into nine zones from the Pleistocene Botryostrobus aquilonaris Zone to the Upper Miocene Lipmanella redondoensis Zone at Site 1150, and 11 zones from the Pleistocene Stylatractus universus Zone to the Middle Miocene Dendrospyris? sakaii Zone at Site 1151. These zones correlate successfully with the studied sequences of many of deep‐sea cores in the Northwest Pacific Ocean and with some sections of onshore Japan. Of 67 important radiolarian bioevents recognized during the study, 29 Pleistocene to Upper Miocene events were directly tied to the geomagnetic polarity time scale through the well‐defined paleomagnetic polarity records, and 21 Upper Miocene events were calibrated based on the diatom biostratigraphy. Of these events, 24 geographically widespread events were selected to test synchroneity and usefulness as time‐horizons within the mid‐to‐high latitude of the Northwest Pacific, involving eight other offshore and onshore sections. Examination showed that most of the zonal boundary events are synchronous within the considered region, and that many diachronous events, most of which are eliminated from the zonal scheme, are unreliable events linked to rare and sporadic occurrences of the species. Radiolarian biostratigraphy of the studied cores clearly indicates three major hiatuses in the Middle Pleistocene, Late Miocene and late Middle Miocene. The latter two hiatuses can be correlated to two global oceanic hiatuses, NH6 and NH3, respectively.     

Conodonts from the Upper Cambrian Sesong and Hwajeol Formations in the Sabuk Area, South Korea

This paper presents a conodont biostratigraphic study on the Upper Cambrian Sesong and Hwajeol Formations in the Sabuk area, Korea. Two samples near the base of the Sesong Slate at the Pukil section contain lower Upper Cambrian conodonts, comprising Furnishina furnishi, F. kranzae, F. pernical, F. triangulate, Hertzina elongata, Laiwugnathus doidyxus?, Phakelodus elongatus, Muellerodus? obliquus, Westergaardodina matsushitai and W. moessebergensis. This is the first conodont record of the Upper Cambrian formations recovered yet in the northern limb of the Paekunsan syncline. The faunal assemblage is correctable with the lower Upper Cambrian W. matsushitai Zone of North China. Four local biozones are recognized in the Hwajeol Formation, i.e. the Proconodontus, Eoconodontus notchpeakensis, Cambrooistodus minutus and Cordylodus proavus Zones in ascending order. This zonal scheme is essentially equivalent to that of the southern limb of the Paekunsan syncline and they are correlatable with zones in other pa     

Le Carbonifère du Maroc central : les formations de Migoumess,de Tirhela et d'Idmarrach. Lithologie,biostratigraphie et conséquences géodynamiquesThe Carboniferous formations of Migoumess,Tirhela and Idmarrach (central Morocco): lithology,biostratigraphy and geodynamic consequences

New biostratigraphical data based on foraminifers, algae and pseudo-algae indicate that the limestone pebbles of the channelized polygenic conglomerates of the Migoumess formation contain Late Visean (V3bγ–V3c) assemblages. That confirms the Westphalian age attributed to this formation by Hollard [Zdt. Geol. Ges. 129 (1978) 495–512]. The Tournaisian age assigned to it by palynology [C. R. Acad. Sci. Paris, série II 310 (1990) 1573–1576] cannot be retained. The Tirhela formation, Late Visean and Serpukhovian (E1) in age, is coeval with the Akerchi formation [Berkhli, thèse d'État, 1999; Berkhli et al., J. Afr. Earth Sci. (accepté)]. The Idmarrach formation, mapped as a thrust sheet [C. R. Acad. Sci. Paris, série II 310 (1990) 1573–1576], is dated as Serpukhovian (E1) and its thrusting is consequently post-Serpukhovian. Palaeogeographic and geodynamic consequences are listed. To cite this article: M. Berkhli, D. Vachard, C. R. Geoscience 334 (2002) 67–72     

Pliensbachian magnetostratigraphy: new data from Paris Basin (France)

Sampling of an industrial drill string from the northeastern Paris Basin (Montcornet, France) provides early Jurassic magnetostratigraphic data coupled with biochronological control. About 375 paleomagnetic samples were obtained from a 145 m thick series of Pliensbachian rocks. A composite demagnetization thermal up to 300°C and an alternating field up to 80 mT were used to separate the magnetic components. A low unblocking temperature component (<250°C) with an inclination of about 64° is interpreted as a present-day field overprint. The characteristic remanent component with both normal and reversed antipodal directions was isolated between 5 and 50 mT. Twenty-nine polarity intervals were recognized. Correlation of these new results from the Paris Basin with data from the Breggia Gorge section (Ticino, southern Alps, Switzerland), which is generally considered as the reference section for Pliensbachian magnetostratigraphy, reveals almost identical patterns of magnetic polarity reversals. However, the correlation implies significant paleontological age discrepancies. Revised age assignments of biostratigraphic data of Breggia as well as an objective evaluation of the uncertainties on zonal boundaries in both Breggia and Moncornet resolve the initial discrepancies between magnetostratigraphic correlations and biostratigraphic ages. Hence, the sequence of magnetic reversals is significantly strengthened and the age calibration is notably improved for the Pliensbachian, a stage for which sections combining adequate magnetic signal and biostratigraphic constraints are still very few.     

陕西韩城寒武纪三叶虫生物地层

陕西韩城寒武系出露良好 ,化石丰富 ,假整合覆盖于厚约 2 0 m的霍山组石英砂岩之上 ,从下寒武统上部至奥陶系为沉积连续。本区寒武系主要以紫色和黄色泥页岩、泥灰岩、灰岩和白云质灰岩为主 ,从下到上可划分为馒头组、毛庄组、徐庄组、张夏组和三山子组。根据在本区寒武系发现的三叶虫化石 ,韩城地区寒武系可划分为 14个生物带 ,自上而下为 :Blackwelderia带 ,Damesella带 ,L iopeishania带 ,Dorpyge richthofeni带 ,Crepicephalina带 ,Manchuriella带 ,Poriagraulos带 ,Inouyops带 ,Sunaspis带 ,H suchuagia带 ,Shantungaspis带 ,Probowmaniella带 ,Weijiaspis带和 Redlichia murakamii带。     

冀北滦平盆地大北沟组叶肢介生物地层特征 与大北沟阶单位层型的建立

滦平县火斗山乡张家沟榆树下村大北沟组（1棚剖面地层连续,顶底清楚,化石丰富,以沉积岩为主夹少量火山岩,可分为3个岩性段。1段含孢粉化石;2至3段化石极为丰富,有叶肢介、昆虫、介形类、双壳、腹足类、鲎虫、鱼、植物等化石。其中叶肢介化石自大北沟组近底部一直分布于顶部,可见至少25个化石层．计5科9属36种,统属于尼斯托叶肢介群（Nestoria Fauna）。自下而上又可进一步划分为3个叶肢介化石带。以最底部化石带中Mstoriapissovi,Jibeilimnadia ovata的首现为标志,即为大北沟阶的开始,榆树下剖面可作为大北沟阶理想的单位层型剖面。根据化石组合、地层层序、区域地层对比及同位素年代资料,大北沟阶的时代应为晚侏罗世,可能更近于晚侏罗世晚期。文中描述了一些叶肢介属种。     

The Llandeilo (Ordovician) series in the core of the Tywi Anticline,Llanwrtyd, Powys,UK

The Llandeilo and Caradoc volcanic rocks that form an inlier near Llanwrtyd, south-west of Builth, Powys, consist of acidic tuffs and basaltic rocks. They are interbedded with marine mudstones deposited in conditions of low oxygenation, and turbidites, slumps and debris flows. The cored Gilfach Farm No. 1 Borehole shows that this igneous activity is of Llandeilo age, extending from the teretiusculus Biozone to the gracilis Biozone. Evidence from exposures suggests that this igneous activity ceased at about the end of gracilis Biozone times (early Caradoc) and was probably extrusive; but evidence from the core, especially the presence of peperites towards its base, also indicates intrusion into wet sediments. Evidence is given for an early Caradoc basin-wide sedimentary event.