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.     

The Maastrichtian-Danian in the SW Zagros Fold-Thrust Belt (S. Iran): An Integration of Planktonic Foraminiferal Biostratigraphy and Gamma-Ray Spectrometry

In this study, the Maastrichtian-Danian boundary was measured and sampled in two stratigraphic sections, the north and south flanks of the Dehnow anticline in Coastal Fars, Southern Iran. This boundary was also investigated in the drilled exploratory well-1 in the same region. The lithology of the Maastrichtian-Danian deposits consists of glauconitic, phosphatic argillaceous limestones and marlstones. 30 genera and 77 species of planktonic foraminifera have been determined. The recognized biozones are the Gansserina gansseri Interval Zone, and the Contusotruncana contusa Interval Zone, which indicates latest Campanian to middle Maastrichtian age for the upper part of the Gurpi Formation. In addition, the Eoglobigerina edita (P1) Partial Range Zone, Praemurica uncinata (P2) Lowest Occurrence Zone, Morozovella angulata (P3) Lowest Occurrence Zone and Globanomalina psudomenardii (P4) Taxon Range Zone represent a Danian to Thanetian age for the lower part of the Pabdeh Formation. From the absence of the Abathomphalus mayaroensis Interval Zone, Pseudoguembelina hariaensis Interval Zone, Pseudotextularia elegans Interval Zone, Plummerita hantkeninoides Interval Zone, Guembelitria cretacea (P0) Partial Range Zone and Parvularugoglobigerina eugubina (Pα) Total Range Zone, it can be deduced that there is a paraconformity across the Maastrichtian–Danian boundary in the studied area, this hiatus encompassing the late Maastrichtian and the earliest Danian. Danian deposits from the study area contain reworked glauconitized macrofossils, planktonic and benthic foraminifera of the Cretaceous. The obtained surface gamma-ray spectrometry logs resemble the exploratory well-1 gamma-ray wireline log.     

华北板块奥陶纪牙形石生物地层研究回顾及在西北缘区新进展

牙形石在以碳酸盐岩为主的华北奥陶系划分对比中占有举足轻重的地位。针对华北奥陶纪牙形石的研究已持续近半个世纪,总体上可以分为两个阶段:第一阶段自20世纪70年代到21世纪初,第二阶段为最近10年(2010—2020)。第一阶段以建立牙形石生物地层序列为目标,主要为解决石油勘探过程中地层时代的确定和地层对比的需求;第二阶段的研究以修订化石带为主,目的是与国际地层研究接轨。近年来在华北板块西北缘的工作显示,该区奥陶纪牙形石在纵向上具有显著的生态变化,可分为达瑞威尔期中期、达瑞威尔期晚期—桑比期中期、桑比期晚期—凯迪期中期3个时段。第一时段以介于北美中大陆区和北大西洋区之间的热带台地边缘型牙形石为特征;第二时段以北大西洋型为主混有少量亚澳型牙形石为特征;第三时段以亚澳型和北美中大陆型牙形石混生为特征。在华北西北缘尽可能使用广布性标准牙形石属种进行化石带厘定,共识别牙形石带12个,自下而上分别是达瑞威尔期Histiodella cf. holodentata间隔带、Histiodella kristinae谱系带、Histiodella bellburnensis延限带、Dzikodus tablepointensis间隔带、Eoplacognathus suecicus间隔带、Pygodus serra间隔带和Pygodus anserinus(早期型)间隔亚带,桑比期Pygodus anserinus(晚期型)间隔亚带和Belodina compressa间隔带,凯迪期Belodina confluens间隔带、Yaoxianognathus neimengguensis间隔带和Yaoxianognathus yaoxianensis间隔带。由于部分化石带与国际同名带的对比还存在一些矛盾,尚需今后进一步解决。     

Cretaceous Environments of Afghanistan:A Synthesis Based on Selected Sections

The Cretaceous of Afghanistan is marked by great facies diversity. The evolution of Cretaceous basins is part of a complex accretionary history involving three distinct tectonic units namely the Asian (Russian) Block separated from the Indian plate by a rather well defined transcurrent fault (Chaman-Nuski). The southwestern component is representedby the Iran-Afghanistan plate. The Lower Cretaceous of the Asian Block is represented by the Red-Grit Series which isconformable to the underlying Upper Jurassic sequences. The transition is marked by evaporitic facies dominated by salt,gypsum and marl deposits. In south Afghanistan volcanic rocks occur at Farah, with the emplacement of plutonics inwest-central Afghanistan. The Upper Cretaceous of north Afghanistan is marked by richly fossiliferous, lime stone-dominated sequences. The Upper Cretaceous of southern Afghanistan is marked by strong ophiolitic magrmatism.     

塔里木盆地亚科瑞克剖面奥陶系牙形石生物地层初步研究

塔里木盆地西北缘乌什县东南亚科瑞克剖面奥陶系发育，并且该剖面也是塔里木盆地上奥陶统沉积最为齐全的露头剖面之一，尤其是上奥陶统的中—上部发育了许多重要的牙形石属种。本文通过对剖面上灰岩层样品的系统采集和牙形石分析鉴定，将该剖面的奥陶系分为4个牙形石组合和2个牙形石带。自下而上依次为：Serratognathus diversus - Bergstroemognathus extensus 组合 , Protopanderodus calceatus - Periodon aculeatus 组合 ,A phelognathus sp. - Tasmanognathus sp. 组合, Belodina confluens- Phragmodus undatus 组合 , Yaoxianog-nathus neimengguensis 带和 A phelognathus pyramidalis带。其中，上奥陶统上部牙形石的重要属种A. pyramida-lis、A. politus、Y. yaoxianensis 和 A. neimengguensis以及上奥陶统上部的A．pyramidalis带与Y．neimengguensis带是首次在柯坪地层分区发现。这些发现初步解决了塔里木盆地覆盖区与露头区上奥陶统不能进行精细生物地层对比的问题。     

柴达木盆地昆2井古近系下干柴沟组上、下段分界探讨

青海油田和中国石油大学（北京）合作,在柴达木盆地昆2井井深5120～5140 m发现南星介化石带。通过对比柴西地区和柴北缘地区南星介化石带的发现层位,并将该化石带顶界在地震剖面上进行标定追索,认为南星介（Austrocypris）是柴达木盆地下干柴沟组下段上部的标准化石。从发现南星介化石并标定有T4反射界面的冷科1井（或深88井）开始,沿地震测线向昆2井进行追索,经时深转换,将昆2井5040 m处标定为下干柴沟组上段与下段的分界。两井之间T4（下干柴沟组上、下段分界）、南星介化石带顶界和T5 （下干柴沟组底）呈3条平行线,表明其得到闭合验证,下干柴沟组上、下段的分界划分合理。因此,生物地层学与地震地层学相结合,可以有效地对比柴达木盆地陆相新生界红色碎屑岩区的地层。     

Sequence and isotope stratigraphy of Late Triassic distal periplatform limestones from the Northern Calcareous Alps (Kälberstein Quarry, Berchtesgaden Hallstatt Zone)

Received: 24 September 1998 / Accepted: 14 November 1999     

Reply to discussion of Jamaican cenozoic ichnology: review and prospectus: (v. 50, p. 364–382)

Mitchell and Ramsook comment on the lithostratigraphic assignment of Jamaican Cenozoic ichnofossils discussed in Donovan et al. They argue that the Paleogene Richmond Formation should be subdivided to produce a ‘Moore Town formation’ in eastern Jamaica, but the latter remains undefined as a lithostratigraphic unit and no new lithostratigraphic evidence is produced to support their supposition. Further, their use of a flawed table of trace fossil distributions does not support their thesis. The distribution of trace fossils in the White Limestone Group presented by Donovan et al. follows the lithostratigraphic scheme that was current at the time that the research was originally undertaken in the early 2000s. Yet, whatever lithostratigraphic scheme is utilised for the island, it is apparent that the more accurate data is provided by the biostratigraphy of the larger benthic foraminifers. Copyright © 2015 John Wiley & Sons, Ltd.