山东东营凹陷早第三纪沙一段介形虫丰度的不均匀性及其地质…

东营凹陷四个钻孔（２－下２－观１８、滨２９７、牛１０１、樊１０１）沙河街组一段岩心样品介形虫化石丰度统计表明：１）不同的岩性介形虫化石丰度可以有很大不同;２）同一钻孔垂向上不同层段中介形虫化石丰度也显示出不均匀性;３）在岩心层面上,介形虫化石的分布有六种形式;密集分布、零星分布、簇状分布、条带状分布、虫穴充填、裂缝充填、除前两者外,均显示出层面上化石分布的不均匀性,造成上述化石丰度不均匀性的原因包     

东营凹陷沙河街组介形虫化石保存特征研究及应用

本文对山东东营凹陷沙河街组介形虫化石壳体的保存特征进行了研究。研究结果表明：沙河街组介形虫化石壳体颜色可分为浅色、中色和深色三种类型;按有无充填物,可分为未充填壳和充填壳两种,其中充填壳充填物的成分有方解石、白云石、黄铁矿和泥质四种;按完整程度有双瓣壳、单瓣壳和碎壳。文中对这些保存特征形成的原因进行了讨论,最后以一口井的研究结果为例,探讨了介形虫保存特征在古湖泊学及石油地质方面的应用。     

松辽盆地松科1井南孔晚白垩世介形类生物地层

松科1井是世界上第一口陆相白垩纪科学钻井,其南孔获取自泉头组三段顶部至嫩江组二段底部的连续地层记录。本文以松科1井南孔岩心样品介形类化石的系统鉴定和统计分析为基础,共建立15个介形类化石组合带,自下而上分别为：1）C ypridea subtuberculis perga-Mongoloc ypris longicau...     

松辽盆地D80井嫩一段介形类化石壳体特征及生物地层

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。     

青海柴达木盆地东部不同盐度湖泊四季现生介形虫的分布特征及其环境指示意义

2014年我们对柴达木盆地东部盐度各异的四个湖泊,可鲁克湖、托素湖、尕海和小柴旦湖,分四季进行现生介形虫调查研究,探索柴达木盆地现生介形虫在盐度不同的水体中的分布规律,并分析了不同介形虫属种与其生存环境间的相互关系。结果表明,在所调查的4个湖泊中共分布有介形虫5属11种,其中在半咸水的托素湖中只分布有2个种,Eucypris inflata为优势属种,在四季均有产出,但在春、夏、秋三个季节13℃—20℃的温度范围内丰度巨大,而另一属种E.rischtanica只在春季有少量出现。可鲁克湖中虽然介形虫属种分布较多,共计4属8种,但全部是单壳,没有发现现生活体;尕海及小柴旦湖水盐度过高,不适宜介形虫的生长发育。     

云南鹤庆晚第四纪介形类生态特征初探

云南鹤庆盆地晚第四纪钻孔剖面分析出介形类13属,32种,多为地方性属种,根据介形类丰度,分异度,百分含量及组合分子在剖面中的分布情况,结合剖面同步分析的总有机碳含量（TOC）,碳-氮比（C/N）,碳酸盐含量,孢粉等数据,并利用已有相关的介形类生态资料,对介形类生态特征进行初步探讨。研究结果表明：温度,矿化度,水流动态,水循环状况,pH值,深度,湖泊流域生产力等环境因素对介形类组合面貌,定量数据,壳饰等特征均有一定影响,其中,介形类丰度,分异度与温度,矿化度关系最为密切。     

川东中侏罗统新田沟组介形类化石壳体方解石化特征及元素成分初步分析

首次利用扫描电子显微镜观察川东新田沟组介形类化石的保存情况,并利用X射线能谱分析部分化石的元素含量及分布。研究发现新田沟组介形类壳体绝大部分方解石化,不同层位介形类壳质方解石化有所不同,且方解石化特点显示其可能与有机质作用有关。通过与前人研究结果对比发现,新田沟组壳体保存处在介形虫壳体埋藏作用的第二阶段和第三阶段。     

介形虫秘史

在古生代地层中,各门类大化石十分发育,因而很少有人去研究微小的介形虫化石。然而在中、新生代地层中,特别是陆相地层和钻井取不到大化石的情况下,介形虫化石已上升成为举足轻重的一个门类了。随着石油、天然气、煤、硫、磷、钾、天然碱等有用矿床的普查、勘探的不断深入,介形虫化石的身价亦与日俱增。什么是介形虫呢?介形虫在古无脊椎动物的分类中,属节肢动物门,甲壳纲,介形虫目。从距今约五亿七千万年的寒武纪开始出现,有的属种一直繁衍至今。介形虫是双壳动物,动物体包隐在左、右两瓣大小相等或不相等的外壳里。一般壳长0.4—4毫米,最大者可达30毫米,属于微体古生物。它们的体形不一,侧视有圆形、半圆形、纺锤形、椭圆形、肾形及菱形等。壳面饰以各种花纹,有的光滑如镜。     

西藏岗巴地区始新世介形虫化石组合

对西藏岗巴盆地层位最高的海相地层——遮普惹组所含介形虫化石进行了分析和研究,共鉴定出22属、33种,建立两个介形虫组合：Paracypris mayaensis sp. nov.-Bairdia zongpuxiensis sp. nov. 组合(下部)和 Phlyctenophora zongpuensis-Semicytherura subsyrnmetros组合(上部);讨论介形虫组合的特征及其地质时代,并与世界上其它地区有关地层进行对比,结合与之共生的有孔虫组合的时代特征,认为含该介形虫组合的海相地层——遮普惹组的时代应为始新世Ypresian-Priabonian早期。描述6种,其中有2新种：Paracypris mayaensis sp. nov.和Bairdia zongpuxiensis sp. nov.。     

松辽盆地泉头组三、四段介形类化石的分布特征与扶、杨油层细分

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。     

Composition, abundance and distribution of macrozooplankton in Culebra Bay, Gulf of Papagayo, Pacific coast of Costa Rica and its value as bioindicator of pollution

The abundance, distribution and composition of the macrozooplankton of Culebra Bay, Costa Rica (10 degrees 38' N - 85 degrees 40' W) were studied at four stations throughout the dry (February-May) and rainy (September-November) seasons of 2000. The samples were collected at two-week intervals using a 500 microm mesh net with a 0.5 m diameter opening. Copepods (23-31%) and ostracods (20-34%) were predominant throughout the year, followed by cladocerans (2.5-14%), zoea (6.6-9.5%), and siphonophores (2.5-7.2%). High densities of zooplankton were obtained in February and March with peak abundance on March 18. The lowest densities were observed on September 3 and November 5. Significant differences in abundances at each station were observed for the groups Acartia tonsa (Copepoda), Ctenophora, Medusae, Ostracoda, Zoea, and Amphipoda. Comparison of the dry and rainy seasons revealed significantly higher zooplankton abundance in the dry season and copepod domination of all stations; during the rainy season ostracods dominated the off-shore areas. Zooplankton abundance and distribution are influenced by upwelling, which occurs during the dry season in Culebra Bay.     

滴水湖现生介形类与水环境因子间的典范对应关系

滴水湖作为人工新建湖泊,其生态系统形成过程中的跟踪数据对重建其他湖泊生态系统具有重要的参考意义。2013年7月和2014年8月对滴水湖现生介形类分布状况及水环境因子分别进行了调查,结果发现,滴水湖湖水盐度范围介于1.4‰—2.0‰之间,属于微咸水湖。12个采样点共鉴定出现生介形类13种,包括非海相类克氏丽星介Cypria kraepelini(G.W.Müller)和无偶斗星介Cypridopsis vidua(O.F.Müller),海相类中华洁面介Albileberis sinensis Hou、向岛薄丽星介Dolerocypria mukaishimensis Okubo、腹结细花介Leptocythere ventriclivosa Chen、东台新单角介Neomonoceratina dongtaiensis Yang et Chen、长新中华花介Neosinocythere elongata(Hu)、闪光似异口介Paradoxostoma nitida Ho、典型中华美花介Sinocytheridea impressa(Brady)、长中华海花介Sinopontocythere elongata(Gou)、古屋刺花介Spinileberis furuyaensis Ishizaki et Kato、美丽刺面介Spinileberis pulchra Chen和丰满陈氏介Tanella opima Chen。应用典范对应分析(CCA)方法对滴水湖12个样点的8种介形类和9个环境因子进行了相关性研究,结果显示:介形类和环境因子间具有明显的相关性;9个环境因子中叶绿素、总磷和电导率对介形类的分布影响最大,总氮和湖水水温对介形类也有一定影响;从物种分布状况看,相对于低分布频度物种,高分布频度(Y>0.01)物种对环境的耐受性更大,其中Cypria kraepelini和Neomonoceratina dongtaiensis对环境因子的敏感性明显高于其它物种。结合历史资料分析发现,不仅自然环境因子(如电导率、水温等),而且人为干扰因素(如总磷、总氮)都对介形类分布的改变起到重要影响。     

Palaeoceanographical changes recorded by Cenozoic deep-sea ostracod assemblages from the South Atlantic and the Southern Ocean (ODP Sites 1087 and 1088)

Cenozoic palaeoceanography of the SE Atlantic and Southern Oceans has been investigated using Late Eocene/Early Oligocene to Quaternary ostracod assemblages from 49 samples of ODP Sites 1087 and 1088. Although the overall abundance of ostracods is relatively low (means of 17 and 49 specimens per sample at Sites 1087 and 1088, respectively) and there is an apparently high level of endemism (ranging from 50% to 80% at Sites 1087 and 1088), three major changes in the faunal assemblages are identified at Site 1087 (denoted A, B and C) and two at Site 1088 (denoted B' and C'). The assemblage boundaries, detected on the basis of stepwise changes in the abundance, diversity, dominance, endemism, faunal turnover and relative abundance of common taxa, coincide broadly with previously identified, ostracod-based palaeoceanographical 'events' discussed by Benson and co-workers over the last two decades. The data do not extend sufficiently far back to record the initiation of Assemblage A, but the faunal change between Assemblages A and B, marked by a decline in abundance, species diversity and faunal turnover, occurs within the Middle Miocene (NN5-6). It coincides with a previously documented palaeoceanographical 'event' at 16-14 Ma which, we suggest, may be related to the initiation of North Atlantic Deep Water (NADW) production and/or an expansion of the East Antarctic ice sheet. Assemblage B' is subdivided into the two Sub-assemblages B'¹ and B'² mainly on the basis of an increase in diversity, a peak in faunal turnover and a drop in the relative abundance of the genus Krithe in early Late Miocene time (NN9, c. 10.5 Ma). The B'¹/B'² Sub-assemblage boundary cannot be related to any previously documented faunal change in deep-sea ostracods. Changes associated with the boundaries between Assemblages B and C, and B' and C', which we believe to be synchronous, both include a decrease in diversity and abundance. In addition, two strong turnover peaks occur near the B'/C' boundary at Site 1088. The B/C and B'/C' boundaries coincide with a previously documented midPliocene 'event' (3.5 Ma) (NN15-16) which may be linked to putative closure of the Straits of Panama and increased production of NADW, the latter in turn leading to increased production of Antarctic Intermediate Water (AAIW) and Antarctic Bottom Water (AABW). Alternatively, fiuctuations in size of the Antarctic ice sheet during possible Pliocene warm periods could indirectly be responsible for the observed midPliocene faunal changes.     

Co-occurrence of hippopodiid siphonophores and their potential prey

It is a truism that the distribution of a predator should reflect that of its potential prey, but this is not well established for marine plankton communities. Purcell (1981) found that many siphonophore species were selective feeders and that one, Hippopodius hippopus, fed exclusively on ostracods. Pugh (1986) speculated that if such a dietary specificity also applied to other hippopodiid species, then a distributional relation between them and ostracods might be expected. This premise is examined using data from Discovery stations in the N.E. Atlantic Ocean. A clear relation is found between the abundance of ostracods and hippopodiids, while copepods have a better relation with other calycophoran siphonophores.     

Pleuston communities are buffered from regional flood pulses: the example of ostracods in the Paraná River floodplain, Brazil

1. It is widely acknowledged that sudden, large‐scale flood pulses are drivers of benthic and planktonic biodiversity change in floodplains. The impact of such pulses on pleuston (biotic communities associated with root systems of floating plants) remains to be demonstrated. Here, we investigate the effects of local and regional drivers on seasonal changes in abundance and diversity of ostracod communities in pleuston. 2. Temporal and spatial distribution patterns of species richness, abundance, diversity and evenness of ostracods associated with the floating water hyacinth, Eichhornia crassipes, in a lentic environment from the upper Paraná River floodplain, were investigated in relation to local, as well as regional, environmental factors. Ostracods were sampled monthly over an annual cycle (March 2004–February 2005). Twenty‐seven species were found, representing the families Cyprididae, Candonidae, Limnocytheridae and Darwinulidae. Both diversity and abundance of ostracod communities showed seasonal changes, although species turn‐over during the year was limited. 3. We tested two hypotheses concerning the causality of these fluctuations: seasonal recruitment and influx of allochthonous ostracods during the flood pulse. Our results indicate that seasonal recruitment is more likely to be the driver of fluctuations in relation to the flood pulse. We postulate that pleuston communities are buffered against possible detrimental effects of flood pulses.     

Butterflies of the Cambrian benthos? Shield position in bradoriid arthropods

Mode of preservation and method of recovery strongly influences our understanding of the life habits of extinct organisms. Bradoriid arthropods were abundant, and diverse members of early Cambrian ecosystems and most life reconstructions display these animals with the two shields of the carapace open in a ‘butterfly’ configuration. This favoured reconstruction is largely based on the abundance of ‘crack‐out’ specimens preserved in this position (e.g. Kunmingella from the early Cambrian of China). In contrast, large collections of acid processed bradoriids from the Arrowie Basin of South Australia (Cambrian Stage 3) are preserved with a narrow gape at the ventral margin or completely closed with the carapace folded along the dorsal midline. The relative abundance of conjoined, closed (or partially closed) specimens from the lower Cambrian Hawker Group succession suggests that at least some bradoriid taxa were capable of withdrawing appendages and tightly closing the shields, challenging the common view that the majority of bradoriids usually held their carapaces open in a ‘butterfly’ configuration during life. New data show that layers of the bradoriid carapace are continuous through the dorsal fold with no evidence for complex articulating structures as in ostracod hinges. The relatively pliable, sclerotized or lightly mineralized calcium phosphate composition of the carapace and the simple, flexible dorsal fold facilitated opening and closing of the shields. Despite not being closely related, ostracods share close biomechanical and ecological similarities with bradoriids. The evolution of more complex articulating hinge structures – together with well‐developed musculature – in ostracods during the Early Ordovician, may have provided more efficient means for shield articulation and movement, thus promoting the ecological success of ostracods throughout the Phanerozoic.     

The first non‐marine ostracod fauna from the Lower Barremian dysodiles of Lebanon

Dysodiles are finely laminated sedimentary rocks rich in organic matter and in exceptionally well‐preserved fossils, hence their petroleum and palaeontological interest. However, few studies focused on the dysodiles of Lebanon, leaving their palaeontological content and their depositional environment largely unknown. Our previous investigations show a variety of well‐preserved lacustrine fossils including ichthyofauna, chelonians, insects, plant debris, gastropods, palynomorphs and ostracods. The present study focuses on the ostracods of five sampling localities from the Lower Barremian of Lebanon. Being the most abundant fossils, ostracods raise some taphonomic and palaeoecological questions that may help us understand the depositional environment and enrich the story of these Early Barremian lakes. Faunal differences between the sampled sections provide clues to the specific characteristics of each lake. The abundance of ‘butterfly’ preservation of carapaces, together with the association of adults and juveniles, indicates calm depositional environments without post‐mortem transport. The assemblages comprise ostracods with known swimming ability (Cyprois and Zonocypris) or that are thought to have been swimmers (Cypridea), while non‐swimmers are absent, suggesting that nektobenthonic ostracods must have lived only in the shallow margins of the lakes or among floating vegetation because hypolimnion conditions were hostile to benthos. This study provides different scenarios on how this fauna ended up preserved in the laminated lake sediments.     

Distribution,abundance and ecology of the meiofauna in a tropical estuary along the west coast of India

The distribution and abundance of subtidal meiofauna in Mandovi estuary of Goa were studied from June 1983 to June 1984. Monthly faunal abundance ranged from 491 to 2791/10 cm² and dry weight biomass from 0.16 to 2.80 mg 10 cm². Free living nematodes were the dominant group contributing over 75% of the total density and 30 to 42% of the total biomass. Among nematodes the deposit feeders were more abundant in fine muddy substratum while epigrowth feeders dominated in sandy substratum.Harpacticoids were next, comprising 6.9 to 8.7% of the total meiofauna number, followed by turbellaria (3.8–4.5%), polychaeta (2.8–3.2%) and ostracods (1.6–4.5%) The contribution of other groups to faunal density was 4.5–6.2%. In the biomass the ostracods contributed most (29.8–54.7%), followed by nematodes (23.8–34.6%). Over 60% of the fauna occurred in the top 2 cm of the sediment and the faunal density reduced significantly with increasing depth in the sediment. The vertical distribution of meiofauna was positively correlated to the vertical distribution of Eh, chlorophyll a and interstitial water. Seasonality was greatly influenced by the south-west monsoon and the fauna quickly repopulated after the monsoon. Salinity, temperature and food influenced the faunal abundance.     

甘肃玉门红柳峡早白垩世下沟组的介形类

本文描述了甘肃玉门红柳峡下沟组的介形类化石共5属4亚属、13种。其中1新属、6个新种、1个比较种。根据介形类特征和地理分布,推测下沟组的时代为早白垩世巴列姆期;同时结合玉门红柳峡下沟组的岩性特征,认为该组为淡水微咸水河湖相沉积。