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 )。     

论我国东部第三纪含油气盆地是否存在海侵海漫海啸

本文以沟鞭藻生态为基础,结合我国东部第三纪盆地的地球化学、古生物、岩相古地理、区域地质和全球海平面变化,论证东部含油气盆地在第三纪时不存在海水侵进。出现有“海相”沟鞭藻、有孔虫和钙质超微化石是由于当时湖泊咸化及富养料造成的。同时认为沟鞭藻是广盐性生物,其最适应于半咸水环境。     

松辽盆地新站地区嫩江组三段孢粉-藻类组合及其环境

依据松辽盆地西南部新站地区嫩江组三段孢粉和藻类化石百分含量纵向变化特征,自下而上划分7个能识别水体盐度变化的孢粉和藻类组合：Cyathidites Pinuspollenites Dinogymniopsis组合,指示缩小的微咸水湖相沉积环境;Dinogymniopsis Leiosphaeridia Pinuspollenites组合,代表水域扩大的微咸水湖相沉积环境;Cicatricosisporites Pinuspollenites Botryococcus组合,代表水域缩小的淡水-微咸水湖相沉积环境;Dinogymniopsis Chlamydophorella Taxodiaceaepollenites组合,反映淡水与微咸水频繁交互变化的浅湖相沉积环境;Cicatricosisporites Pinuspollenites Pediastrum组合,代表水域缩小的淡水湖相沉积环境;Nenjiangella Balmula Cyathidites组合,代表水域范围较大的淡水湖相沉积环境;Cyathidites Trilobosporites Botryococcus组合,指示水域缩小的微咸水湖相沉积环境。     

南海东北部全新世早期高生产力的直接证据

南海东北部的17940站(水深1728m)是西太平洋海区地层分辨率最高的深海剖面之一。用抱粉学方法从92个样品中分析鉴定出的有机壁浮游藻类包括海相沟鞭藻的囊孢和陆相淡水绿藻。前者属旋沟类(GOnyaulacoids)和多甲类(Peridihioids)沟鞭藻,后者为盘星藻(Pediastrum)和双星藻(Zygnema)。就含量而言,沟鞭藻囊抱占浮游藻类的绝大部分,淡水绿藻虽存在于大多数样品中,却含量甚微。采取外加标志法获得浮游藻类浓度后,以下列公式求出两种浮游藻类成分的输人通量浮游藻类输人通量(粒／Cm²·a)=粒／g×g/cm³×cm/a式中．粒／。为g。沉积物(干重)含浮游藻类个体数;g     

塔里木盆地吐依洛克组发现沟鞭藻化石

新疆塔里木盆地西南缘的吐依洛克组化石罕见,以前依据岩性将其定为晚白垩世。郝诒纯等（2001）、郭宪璞（1990）根据在该组所产的有孔虫、介形虫等化石组合,将该组时代划为古新世,并将白垩系与古近系界线划在该组与依格孜牙组之间。本次在该组命名剖面—吐依洛克剖面上部岩性段发现了20余种沟鞭藻化石,增添了新的古生物门类和生物地层材料,这是带有白垩纪与古近纪过渡色彩的沟鞭藻化石组合,其所反映的古环境是温暖的近岸滨海—浅海环境。     

济阳坳陷古近纪沟鞭藻分子化石的分布与控制因素

济阳坳陷古近纪沟鞭藻化石十分丰富,沟鞭藻为有机质富集层的形成作出了重要贡献。三芳甲藻甾烷和甲藻甾烷是沟鞭藻及其祖先在古代沉积物中两种重要的存在形式,并且它们几乎专一性地由沟鞭藻提供。研究发现,沟鞭藻的不同属种,德弗兰藻属、多刺甲藻属、渤海藻类等,均可以提供丰富的三芳甲藻甾烷和甲藻甾烷,但是三芳甲藻甾烷和甲藻甾烷对沉积环境的变化具有不同的响应。在淡水、半咸水、咸水等不同水介质条件下,三芳甲藻甾烷指数稳定分布在0.50～0.96之间,高丰度的三芳甲藻甾烷与地层中丰富的沟鞭藻化石相一致,因而三芳甲藻甾烷是指示沟鞭藻输入的有效分子化石。甲藻甾烷的丰度与古沉积环境存在密切关系,高盐环境有利于甲藻甾烷的形成和保存,随着盐度的降低甲藻甾烷指数在0.04～0.74这样一个较大的范围内变化,其发育程度与有机质沉降过程中和成岩作用早期遭受的微生物降解作用有关,强烈的生物降解不利于甲藻甾烷的保存。     

柴达木盆地始新统沟鞭藻及其油源意义

我国中新生代陆相沉积，特别是咸化湖泊沉积中普遍发现属于“海源陆生”的沟鞭藻化石，由于其良好的生油特性，被认为是我国白垩纪—第三纪陆相油气资源的重要来源。柴达木盆地第三系始新统下干柴沟组是该地区最主要的烃源岩，生油岩及原油中富含公认的沟鞭藻生物标志物4 甲基甾烷和甲藻甾烷，但迄今该地区尚未发现可靠的沟鞭藻化石。本次研究在柴达木盆地北缘昆2井下干柴沟组发现了类型单调但化石丰富的以Subtilisphaera为主的沟鞭藻化石组合，为肯定柴达木盆地第三系原油沟鞭藻的贡献提供了直接化石证据。研究表明，沟鞭藻发育的第三系中始新统可能是本地区最有利的生油层，形成于湿热气候所控制的陆相咸水湖泊。     

东濮凹陷古近系成烃生物特征及其生烃潜力研究

通过光学显微镜和扫描电镜对东濮凹陷古近系沙河街组烃源岩的成烃生物进行了研究。结果显示，研究区沙河街组的成烃生物发育，种类繁多，主要包括沟鞭藻、绿藻、蓝藻、颗石藻等。发育于东濮凹陷北部咸水区的成烃生物优势组合是沟鞭藻、蓝藻、颗石藻，且三者均可形成藻纹层；南部淡水区的成烃生物优势组合是绿藻及高等植物，发育于块状泥岩之中。对分别取于咸水区和淡水区的两个样品进行了热模拟实验，实验结果显示，北部咸水区的蓝藻和颗石藻的生烃潜力高，生油门限低，在低熟阶段即可大量生油，生成低熟油的控制因素是蓝藻的勃发；沟鞭藻和绿藻类的生油门限较高，其中沟鞭藻由于能大量勃发，是重要的成烃生物；南部淡水区的绿藻类较沟鞭藻类生烃潜力更低，生油门限更高。     

东濮凹陷古近系成烃生物特征及其生烃潜力研究

通过光学显微镜和扫描电镜对东濮凹陷古近系沙河街组烃源岩的成烃生物进行了研究。结果显示,研究区沙河街组的成烃生物发育,种类繁多,主要包括沟鞭藻、绿藻、蓝藻、颗石藻等。发育于东濮凹陷北部咸水区的成烃生物优势组合是沟鞭藻、蓝藻、颗石藻,且三者均可形成藻纹层;南部淡水区的成烃生物优势组合是绿藻及高等植物,发育于块状泥岩之中。对分别取于咸水区和淡水区的两个样品进行了热模拟实验,实验结果显示,北部咸水区的蓝藻和颗石藻的生烃潜力高,生油门限低,在低熟阶段即可大量生油,生成低熟油的控制因素是蓝藻的勃发;沟鞭藻和绿藻类的生油门限较高,其中沟鞭藻由于能大量勃发,是重要的成烃生物;南部淡水区的绿藻类较沟鞭藻类生烃潜力更低,生油门限更高。     

黑龙江东部侏罗—白垩系界线附近地层研究新进展

<正> 近年来,随着饶河东安镇具国际性对比标准的海相侏罗—白垩系界线的确定及其相关生物组合带的建立(孙革等,1989),黑龙江省东部地区的海相—海陆交互相—陆相的侏罗—白垩系界线及其附近地层的研究,不断取得新的进展。研究成果之一是,鸡西盆地城子河组时代属早白垩世。在其典型剖面(穆棱河北岸路堑剖面)的城子河组下部,发现含早白垩世凡兰吟—戈特里夫期(Valanginian-Hauterivian)沟鞭藻的海相层(孙学坤、     

Late Mesozoic bivalve faunas from the Tetori Group,Japan

The Tetori Group of Japan ranks amongst the more important Upper Mesozoic strata in East Asia, with common animal and plant fossils throughout and is well suited for analyses of the links between environmental changes and the various animal and plant fossil assemblages. Three marine transgressions (i. e., Bathonian–Oxfordian, Tithonian–Berriasian and Hauterivian–Barremian in age) have been recognized in the Tetori Group, based on ammonite index taxa. These pulses are also reflected in bivalve faunas which comprise, 81 species in 65 genera (marine taxa) and 16 species in 13 genera (non-marine taxa). Many of these are considered as endemic species to the Tetori Group. In view of the fact that the occurrence of non-marine taxa was primarily controlled by environmental conditions, these do not constitute chronological indices. The faunal composition of the first marine transgressive phase is similar to that found elsewhere in southeast Asia, while that of the second one resembles both that of southeast Asia and of northeast China and Far East Russia. Assemblages of the third phase are similar to those of Heilongjiang, northeast China. Currents from the equator and high-latitudes explain these similarities.     

青海省南部侏罗纪地层问题讨论

青海省南部侏罗纪海相双壳类异常丰富.根据近年来新测制的地层剖面和化石资料,本文分析了该区双壳类动物群的时代意义,从而确立了本区侏罗系应包括中,上侏罗统;海相侏罗纪沉积大致自巴柔阶到基末里阶.东特提斯区北缘的弧形地带,诸如青海南部、藏东、藏北、滇西,缅甸掸邦和泰国呵叻等地在中,晚侏罗世基本上属于同一个生态环境较特殊的双壳类生物地理分区,双壳类动物群表现出强烈的地方性色彩,特别是淡水双壳类动物群cuneopsis—Psilunio—Lamprotula组合,半咸水动物群Corbula—Neomindon组合以及淡水（微咸水）动物群Peregrinococha组合完全是该区特有的土著分子,从时代对比意义上来说,它们之间可对比度更高.云南和平乡组双壳类动物群和本区相比较后表明,和平乡组沉积时代大致相当于巴柔期（含早巴通期）.缅甸南瑶系中的双壳类动物群时代不应晚于巴通期.藏东和青海南部产出的奇异蛤动物群时代则应不早于基末里期.     

Palaeoenvironments of the Hoxnian Nar Valley Clay,Norfolk, England: Evidence from an integrated study of diatoms and ostracods

Diatoms and ostracods from the Nar Valley, west Norfolk, England are analysed with a view to establishing marine and freshwater palaeoenvironments of the Hoxnian interglacial Stage. No microfossils were recovered from the non-marine facies, but rich assemblages of both fossil groups were extracted from the marine Nar Valley Clay and these, together with associated sedimentological evidence, indicate that the environment of deposition changed from a relatively nearshore, muddy shelf setting, to one that was more littoral and subject to higher current regimes, with salinities remaining at normal marine levels through both depositional phases. It is suggested that this sequence may reflect a regressional phase towards the close of the Hoxnian Stage, with palaeotemperature evidence from at least one ostracod species suggesting a warmer climate than at present. Non-recovery of microfossils from some of the samples analysed is attributed to unfavourable palaeoenvironmental conditions and/or post-depositional ground-water percolation.     

Confirmation of an Early Cretaceous age for the Qihulin Formation in eastern Heilongjiang Province, China: constraints from a new discovery of radiolarians

The coal-bearing, alternating marine and non-marine Longzhaogou Group in eastern Heilongjiang, northeastern China, has long been considered as Jurassic, or mainly Jurassic, in age. However, recent studies have demonstrated that the ammonites and dinoflagellate cysts are of Early Cretaceous age. This has now been confirmed by new radiolarian evidence. The radiolarian fauna recovered from the upper Qihulin Formation of the Longzhaogou Group consists of nine poorly preserved species referable to nine genera. Novixitus is a Cretaceous genus, and the specimens of Archaeodictyomitra sp. and Xitus sp. recovered resemble A. vulgaris Pessagno and X. spicularius (Aliev), respectively.     

Exceptionally preserved fossil assemblages through geologic time and space

Geologic deposits containing fossils with remains of non-biomineralized tissues (i.e. Konservat-Lagerstätten) provide key insights into ancient organisms and ecosystems. Such deposits are not evenly distributed through geologic time or space, suggesting that global phenomena play a key role in exceptional fossil preservation. Nonetheless, establishing the influence of global phenomena requires documenting temporal and spatial trends in occurrences of exceptionally preserved fossil assemblages. To this end, we compiled and analyzed a dataset of 694 globally distributed exceptional fossil assemblages spanning the history of complex eukaryotic life (~ 610 to 3 Ma). Our analyses demonstrate that assemblages with similar ages and depositional settings commonly occur in clusters, each signifying an ancient geographic region (up to hundreds of kilometers in scale), which repeatedly developed conditions conducive to soft tissue preservation. Using a novel hierarchical clustering approach, we show that these clusters decrease in number and shift from open marine to transitional and non-marine settings across the Cambrian-Ordovician interval. Conditions conducive to exceptional preservation declined worldwide during the early Paleozoic in response to transformations of near-surface environments that promoted degradation of tissues and curbed authigenic mineralization potential. We propose a holistic explanation relating these environmental transitions to ocean oxygenation and bioturbation, which affected virtually all taphonomic pathways, in addition to changes in seawater chemistry that disproportionately affected processes of soft tissue conservation. After these transitions, exceptional preservation rarely occurred in open marine settings, excepting times of widespread oceanic anoxia, when low oxygen levels set the stage. With these patterns, non-marine cluster count is correlated with non-marine rock quantity, and generally decreases with age. This result suggests that geologic processes, which progressively destroy terrestrial rocks over time, limit sampling of non-marine deposits on a global scale. Future efforts should aim to assess the impacts of such phenomena on evolutionary and ecological patterns in the fossil record.     

Correlation and paleoenvironments of middle Paleogene marine beds based on dinoflagellate cysts in southwestern Patagonia,Argentina

An understanding of paleonvironmental and paleoceanographic evolution of the Southwestern Atlantic Ocean during the Palaeogene is prevented by the lack of precise tools to date and correlate the sedimentary units. Palynological samples collected in the upper portion of the Man Aike Formation, which crops out southern Lago Argentino area, in the southwest of the Austral Basin (50°21′45″S–72°14′30″W), contain well preserved marine organic dinoflagellate cysts, which are potentially important biostratigraphic and paleoenvironmental indicators. Herein we describe the composition of the Man Aike Formation's dinoflagellate cyst assemblages and compare them to similar assemblages collected in the same basin in the upper member of the Río Turbio Formation using Compositional Statistical Analysis. The dinoflagellate cyst assemblages from the upper part of the Man Aike Formation are highly correlated to the assemblages from the upper member of the Río Turbio Formation from outcropping sections (51°31′13″S–72°15′11″W) and with the lower part of sediment cores drilled by Yacimientos Carboníferos Fiscales in the Río Turbio Formation area. These dinoflagellate cyst assemblages show a very low correlation with the assemblages from the upper part of the Yacimientos Carboníferos Fiscales's cores. The comparison of our results with the high-resolution Southern Pacific Ocean dinoflagellate cyst zonation for the late Palaeocene to late Eocene allow us to date some of the dinoflagellate events recorded in formations of southwestern Patagonia. The assemblages from the Man Aike Formation and the lower part of the upper member of the Río Turbio Formation relate to the zones SPDZ11 and SPDZ12 and are assigned to the mid-middle Eocene (late Lutetian to early Bartonian). The biostratigraphy proposed herein constrains the age of the Man Aike Formation and equivalent units based on calcareous microfossil data, mollusks affinities and ⁸⁷Sr/⁸⁶Sr isotopic values to an age ranging between ∼42 and 39 Ma. The assemblages from the upper part of the upper member of the Río Turbio Formation relate to the SPDZ13 Zone, which corresponds to the late Eocene (early Priabonian). The dinoflagellate cyst assemblages indicate that they were under the influence of relatively warm, marine open waters in an inner-shelf environment for the lower part of the sections. In the upper part of the sections, the assemblages suggest shallow marine waters associated with coastal areas and high trophic levels, possibly as a result of freshwater inputs.     

Palynostratigraphy of the Zorritas Formation,Antofagasta region,Chile: Insights on the Devonian/Carboniferous boundary in western Gondwana

The Middle Member of the Zorritas Formation in the Antofagasta region of northern Chile, yielded terrestrial and marine palynomorph assemblages which span the Devonian/Carboniferous boundary. The assemblages show a clear predominance of terrestrial palynomorphs with 70 miospore species, 18 marine phytoplankton species, two non-marine algae and one chitinozoan species, all coming from 15 productive levels. Palynomorphs are poorly preserved and most of them are reworked. Three palynological associations are recognized based on miospores. These are assigned to the Tournaisian–Visean, Tournaisian and probable latest Famennian. Age assignments are discussed in the frame of the spore zonal schemes established for Euramerica and western Gondwana. The stratigraphical distribution of spores allows the identification of the probable position of the Devonian/Carboniferous boundary within the Zorritas Formation. This system boundary is proposed for the first time in Palaeozoic sedimentary rocks of northern Chile. The presence of Gondwanan typical miospore species indicates affinities with this palaeocontinent even though the Tournaisian and Tournaisian–Visean miospore associations support the cosmopolitanism already suggested for the early Carboniferous flora. The significant number of reworked palynomorphs together with the sedimentological analysis of the studied sections, suggest that these deposits were severely impacted by the climatic change and major sea level fluctuations. Similar conditions were recorded in coeval western Gondwana basins.     

The Pleistocene palaeoenvironment and stratigraphy of Flatey island (northern Iceland): a preliminary assessment based on palynomorphs

For the first time, palynological data (pollen, spores and dinoflagellate cysts) from Pleistocene outcrop and core deposits from Flatey, off northern Iceland, are presented. The study provides a reconnaissance stratigraphical assessment of the deposits, the correlation between the Pleistocene of Flatey and the well‐known Tjörnes section on the mainland, and the reconstruction of the Pleistocene palaeoenvironment. The preservation of the assemblages is poor to moderate, whereas the diversity and richness are moderate to high. The pollen and spores indicate vegetation composed mainly of sedges and heath, comparable to the vegetation in the Tjörnes area during deposition of the Pleistocene Breidavík Group. Analysis of dinoflagellate cyst assemblages from an outcrop sample allowed their assignment to the Lower Pleistocene dinoflagellate cyst zone DAZ5, previously defined in the Tjörnes section. A core sample yielded a dinoflagellate cyst assemblage unknown from the Tjörnes area. The dinoflagellate cyst data combined with the palaeomagnetic record, the radiometric dating of lavas, and the position of the diamictites and tuff layers allowed refinement of the previously proposed stratigraphical correlations between the Tjörnes area and the Flatey core. The deposition of the sequence from the Flatey core took place during the Matuyama, i.e. between 2.59 and 0.78 Ma, and several hiatuses are postulated. The Lower Pleistocene dinoflagellate cyst assemblages from the outcrop sample bear similarities to those recovered from fully marine subsurface samples on the northern shelf of Iceland within the Polar Front realm. Similar oceanographical conditions influenced by the Irminger Current and the East Icelandic Current can be inferred for Early Pleistocene times.     

Dinoflagellate cysts from the Upper Bajocian–Lower Oxfordian of the Dalichai Formation in Binalud Mountains (NE Iran): their biostratigraphical and biogeographical significance

The Binalud Mountains of NE Iran represent the easternmost extension of the Alborz Range. After the Mid-Cimmerian orogenic event and rapid subsidence, the deep marine sediments of the Dalichai Formation were deposited. A well-preserved section of the formation was sampled for palynological purposes. The study revealed diverse and nearly well-preserved dinoflagellate cyst assemblages. Thirty-six dinoflagellate cyst species identified lead to identification of four biozones: Cribroperidinium crispum (Late Bajocian), Dichadogonyaulax sellwoodii (Bathonian to Early Callovian), Ctenidodinium continuum (Early to Late Callovian), and Ctenidodinium tenellum (Early Oxfordian) biozones. The close similarities of dinoflagellate cyst assemblages between Binalud Mountains, NE Iran, with those of Alborz Mountains (Northern Iran) during Middle Jurassic confirm the connection between two sedimentary basins during this time in Iran. Meanwhile, this biozonation corresponds largely to that established in Northwest Europe and reveals the marine connection between NE and North of Iran with Northwest Europe and the Northwestern Tethys during the Late Bajocian to Early Oxfordian.