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1.
松辽盆地白垩纪介形类生物地层学特征   总被引:8,自引:0,他引:8  
本文详细论述了松辽盆地白垩系介形类属、种数量及壳饰变化在纵向上的分布规律和介形类组合特征的生物地层学意义。认为介形类属的分布是岩石地层组划分的重要依据,种的分布控制了岩石地层段的划分,并可将萨尔图油层、葡萄花油层和高台子油层进一步细分。同时指出松辽盆地介形类的盛衰与湖盆的发育关系密切,介形类的演化周期与湖盆的发育、收缩和沉积旋回相一致,在湖盆最发育的时期,也是介形类繁盛的高峰,湖盆发育的初期和末期,往往是介形类的发生和衰退期。  相似文献   

2.
松辽盆地嫩江组一段富含介形类化石,是系统研究Santonian期陆相介形类的理想层位。论文对中央坳陷区D80井嫩一段的介形类化石进行了系统的分类、生物地层和壳体特征分析。鉴定出介形类化石11属30种,划分出6个介形类化石带,并与前人的研究结果进行了对比;描述了该段介形类化石的壳体结构,共识别出4种壳饰类型,8种壳形结构,基于介形类壳体特征和其他证据,初步探讨了该时期湖盆湖平面的变化特征,显示出嫩一段时期松辽湖盆湖平面经历了由深逐渐变浅的过程。  相似文献   

3.
本文简要叙述了松辽盆地泉头组三、四段的沉积特征,详细讨论了泉头组三、四段及其所属扶余、杨大城子油层介形类化石的分布,总结出划分油层和油层组的介形类标志化石。利用这些介形类标志化石可进一步将扶余油层细分为三个油层组,杨大城子油层细分为五个油层组,为油层细分层对比提供了古生物依据。  相似文献   

4.
在对杏104井,杏1—丁3—检323井和塔3井等3口优选井的介形类化石鉴定的基础上,通过对3口优选井涉及研究层位的87块介形类化石样品进行统计分析和编制介形类主要种的地层分布延限图、开展介形类生物地层学研究,建立松辽盆地晚白垩世嫩江组一段介形类化石带7个,包括新建介形类化石带1个,修订介形类化石带1个,并详细描述这7个介形类化石带。  相似文献   

5.
海拉尔盆地介形类化石组合及其生物地层特征   总被引:2,自引:0,他引:2  
本文简要概述了海拉尔盆地的沉积特征及其地层层序,深入分析了介形类化石纵、横向展布规律,建立了5个化石组合序列:1.Limnocypridea subscalara-Hailaeria dignata组合;2.Cypridea badalahuensis-Hailaeria cretacea组合;3.Ilyocyprimorpha hongqiensis-Rhinocypris rivulosus组合;4.Altanicypris obesa-Talicypridea triangulata组合;5.Chinocypridea augusta-T alicypridea qingyuangangensis组合。进而根据介形类组合及其分布特征,讨论了介形类化石的生物地层特征及其在地层划分对比中的重要意义。  相似文献   

6.
内蒙古海拉尔盆地南部地区晚白垩世青元岗组介形类   总被引:1,自引:0,他引:1  
内蒙古海拉尔盆地南部探井青元岗组红色碎屑岩中发现较丰富的介形类化石,即下段的Ahanicypris obesa-Talicypridea triangulata组合和上段的Chinocypridea augusta-Talicypridea qingyuangangensis组合,这些介形类化石地方性色彩强烈,表现为以具冠状壳喙类型的Ahanicypris,Talicypridea,Chinocypridea和网纹发育的Harbinia等属繁盛为特征,反映了中国东北地区晚白垩世晚期介形类动物群面貌。根据介形类化石组合特征及其分布规律,可以与松辽盆地晚白垩世四方台组的介形类动物群对比,时代为晚白垩世Maastrichtian期。  相似文献   

7.
大庆油田介形类化石在油层对比中的应用   总被引:1,自引:0,他引:1  
松辽盆地白垩纪地层颇为发育,剖面完整,地层分布广泛,沉积厚度大,其中含有丰富的化石,如介形类、叶肢介、腹足类、瓣鳃类、植物、少量的爬行类、昆虫及鱼类等。尤其是介形类化石分布广泛,数量多,保存很好。通过多年的地质勘探工作,古生物工作者对白垩纪地层中的介形类化石进行了较详细的研究,从纵向上建立了14个介形类化石组合(表Ⅰ),为区域地质勘探进行地层划分和对比起了一定的作用。在  相似文献   

8.
广东三水盆地晚白垩世的介形类动物群   总被引:1,自引:0,他引:1  
依据24口钻井及4条地表剖面372个样品的采集和分析,三水盆地晚白垩世的介形类动物群含介形类化石28属81种,本文描述其中24属62种,包括1新种.此介形类动物群在数量上以女星介科和玻璃介科最繁盛,次为背足介科、湖花介科和类女星介科,依其横向分布及纵向变化规律,划分为Talicypridea和Porpocypris两个动物群及Talicypridea amoena带、Porpocypris globra带和Porpocypris sphaeroidalis带等3个化石带.依据介形类化石三水组可与南雄群对比,时代属晚白垩世早--中期.大塱山组与上湖组坪岭段对比,时代应属晚白垩世晚期.  相似文献   

9.
本文描述和图解介形类化石10属、4亚属和14种,包括1新属(Paraulrichia)和6新种。其中古足目类8属、3亚属和12种;豆石目类1属、1亚属和1种;显壳亚目类1属和1种。这些介形类化石分别采自云南宁蒗大槽子泥盆系剖面大槽子组和碳山坪组。根据介形类组合特征,大槽子组的地质时代为晚埃姆斯期,碳山坪组下、中部的地质时代可能属晚埃姆斯期。介形类生态组合属古足目-平足目集群,代表局限的碳酸盐台地环境。在生物地理上,与泥盆纪华南介形类动物地理区系一致。  相似文献   

10.
该文研究的介形类化石来自云南东部陆良、曲靖及昆明盆地上第三系茨营组和第四系更新统,计13属、1亚属、22种,其中包括13新种。根据介形类同种分布特征可建立4个化石组合。通过介报类化石组合特征及同种在地层中的分布,将云南东部地区晚新生代地层进行了重新划分。  相似文献   

11.
密云水库的浮游植物群落结构与密度   总被引:37,自引:0,他引:37  
 1998年的调查研究显示,密云水库库区水体的浮游植物群落为硅藻(Bacillariophyta)—绿藻(Chlorophyta)型,细胞密度为358.76×104·L-1。湖泊的营养特征为浮游植物响应型。1988~1998年库区水体总氮增长48.7%,总磷增长31.2%,浮游植物细胞密度增长41.7%,库区水体已为中营养,并出现了富营养型浮游植物指示种类,例如斜生栅藻(Scenedesmus obliquus(Turp).Kütz.),铜绿微囊藻(Microcystis aeruginosa Kütz.),湖泊色球藻(Chroococcus limneticus Lemm.)。水体向富营养化发展趋势明显。应加强水环境保护,增加密云水库流域植被覆盖度,净化、涵养水源,以保证密云水库向北京市供水的质量和数量。  相似文献   

12.
本文首次报道了湖北京山地区早三叠世有孔虫动物群,计6属15种,其中包括4新种,在对该动物群分析基础上,作者建立了Aulotortuschialingchiangensis-Dichospirasinensis组合带,通过对其古生态特征及生物相研究,揭示了该动物群的生活习性与生态环境的关系,简述了该有孔虫动物群的发现在地层划分对比及油气勘探中的意义。  相似文献   

13.
The relative effects of shell destruction, transportation, and time-averaging have been assessed in seventeen soft-bottom, benthic fossil collections from the Pennsylvanian Wewoka Formation in Hughes County, Oklahoma. Invertebrates were identified to species level, and each was subject to a taphonomic evaluation to determine whether it was in place. Species that were not deemed parautochthonous (living at the location of collection shortly before final burial) were eliminated from the faunal lists to reduce the effects of time-averaging and transportation in the fossil assemblages. Both reciprocal averaging and non-metric multidimensional scaling ordinations revealed two biofacies. These were distinguished using both presence/absence data and numerical counts of species despite an overwhelming number of taxa occurring in both biofacies. Comparison between ordinations based on entire faunal lists with those based on parautochthonous faunal lists indicates that the two biofacies faithfully reproduce differences in the living distributions of member taxa but that the two biofacies underwent different degrees of time-averaging and transportation. Time-averaging leads to accumulation of taxa over time, thereby making presence/absence composition of collections more similar. Transportation, on the other hand, homogenizes originally patchy population distributions and makes relative abundances more uniform. Based on differences in abundances and presence/absence patterns, the stratigraphically lower biofacies underwent more transportation and more time-averaging than the upper biofacies.  相似文献   

14.
P. Anadón  R. Julià 《Hydrobiologia》1990,197(1):291-303
A reconstruction of the early Pleistocene paleohydrochemistry based on the Mg, Sr and Ca content of the Cyprideis valves is presented for shallow lacustrine sequences of the Baza basin. A large number of environmental changes in this marginal area has been recorded by the recurrent alternation of two fossil assemblages which differ in their salinity requirements. Measurements of the Sr/Ca and Mg/Ca ratios of individual calcite shells of Cyprideis show that the water in the higher saline stages (with thalassic organisms indicating marine-like conditions) was of non-marine origin. The Sr/Ca values of Cyprideis valves from sands deposited during a saline water phase show lower values than those from an overlying carbonate sequence which was formed under lower salinity conditions. These unexpected values are assumed to be the result of major changes in the chemical composition of the water in shallow, littoral ponded areas of a hydrologically complex lake. In the sequences that originated in these areas, Sr/Ca values may be used only as salinity indicators within each portion of the sequence formed in a single, continuous evolution. In more open areas, the wide fluctuations of Sr/Ca and Mg/Ca recorded in ostracodes from individual layers of rippled ostracode-shell sands probably reflect the mixing of valves from changing short-term environmental conditions.  相似文献   

15.
Zenetos, A. 1991 01 15: Re-evaluation of numerical classification methods for delimiting biofacies and biotopes in an estuarine environment. Lethaia . Vol. 24. pp. 13–26. Oslo. ISSN 0024–1164.
To test the applicability of numerical classificatory methods in defining biotopes and biofacies, several sets of data were combined using alternative measures of similarity and clustering techniques. In both types of analysis (biofacies and biotopes), results showed that binary data contain enough information and can give as good a picture as the quantitative data, provided [hat the appropriate techniques are used. Despite the inadequacy of the living mollusc data. biotope patterns produced by living and subfossil molluscs are similar, suggesting negligible post-mortem transportation and burial of the fauna in its place of occurrence. The biotopes delineated in this study are consistent with Eastwood's (1977) 'textural facies' patterns based on the sediment size distribution. In this line, it is suggested that the grain size of the substrate is the main factor determining the distribution of molluscs in the Eden estuary. Moreover. the fact that the same cluster analysis combination (D-coef./Ward's clustering) based on independent variables (fauna and sediment size distribution) led to similar results. emphasizes the objectivity of the methods used and the stability of the clusters generated. Mollusca. numerical taxonomy. biotopes. biofacies. Eden estuary .  相似文献   

16.
朝鲜南部Machari组Olenoides带的Agnostus(Ptychagnostus?)orientalis Kobayasbhi一种应归于Agnos-totes(Pseudoglyptagnostus)Lu,1964一属,时代是晚寒武世长山期,不是早期中寒琥世,小林贞一的Olenoides带是中及晚寒武三叶虫混杂在一起的一个化石带。他建立的该组5个化石带也有问题。Coreolenus,Ch  相似文献   

17.
The Middle Ordovician conodont genera that are suitable for palaeoenvironmental interpretations from the epicontinental Baltoscandian platform have been identified and evaluated to establish and describe conodont biofacies and their relationship to global cooling. The construction of biofacies was based on multivariate statistical analyses of more than 375 700 conodont specimens from 520 samples and 21 localities across Baltica. Three distinct, recurrent and laterally extensive conodont biofacies existed across the Baltoscandian platform of the Baltica continent during the Dapingian and early to middle Darriwilian stages (Middle Ordovician). A relatively shallow water conodont assemblage named the Baltoniodus–Microzarkodina Biofacies characterized the inner shelf localities in central Sweden, Estonia, Russia and Ukraine. In the distal shelf areas, patterns are more complex. Here, genera of the Periodon Biofacies characterized the shelf margin areas of the Scandinavian Caledonides facing the relatively warm Iapetus Ocean towards the north, whereas the Protopanderodus Biofacies dominated the distal shelf areas facing the cooler Tornquist Sea towards the south‐west. Although these three main biofacies continued to dominate during the succeeding Darriwilian stage, distinct changes in the distribution of biofacies took place during the transition from the Dapingian Stage to the Darriwilian. We argue that the biofacies change was triggered by a regressive event related to early Darriwilian cooling, and that the palaeoclimatological changes influenced the Baltic conodont faunas near the Tornquist Sea margin before those of the Iapetus margin (early vs middle Darriwilian).  相似文献   

18.
Abstract:  The earliest terebratulids from Central Asia (Tadzhikistan), Podolia (Ukraine) and Novaya Zemlya (Russia) are described and include the new genus Nordothyris. Cranaena tinctoradiata Cooper and Cloud and Cryptonella melonica (Barrande) are revised for first time. The stratigraphical levels of the species studied and their biofacies are also described.  相似文献   

19.
The objective of this study is a paleobathymetric reconstruction of the depositional environment during the Cretaceous (Aptian-Maastrichtian) on the northern flank of the Eastern Venezuelan Basin. The model is based on the presence of benthic foraminifera in 17 well sections, spread across the paleoslope in a passive margin. Cluster analysis separates five distinct assemblages of foraminifers. The analysis is based on the assumption that the species must occur in 10% or in at least two wells of the area. The R-mode for each well provides clusters of species that are similar in distribution and abundance trends. These clusters together with the diversity and abundance of planktic foraminifers, dinoflagellates, pollen, spores, calcareous nannofossils, and sedimentological data help to delineate the biofacies. The biofacies are distributed in a pattern from the updip position (southwest) to the downdip position (northeast). The shallowest biofacies (0–50 m) is represented by Ammobaculites sp., Haplophragmoides sp., Lituolidae, with abundant terrestrial palynomorphs and dinoflagellates. Abundant species in depths greater than 100 m are Praebulimina carseyae, Epistomina lacunosa, Gavelinella sp., Buliminella sp., and Pullenia cretacea. This biofacies interpretation allows us to establish a paleocoast orientation during the Aptian-Maastrichtian.The establishment of the age-paleobathymetry relationships in this area provides the basis for the stratigraphic reconstruction of the Cretaceous in the Eastern Venezuelan Basin, thus reducing the risk for oil exploration.  相似文献   

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