新疆塔里木盆地西部晚二叠世轮藻类

本文研究的晚二叠世轮藻化石产自新疆塔里木盆地西南部之地表及井下剖面中,计有2属4种,其中2新种(Stomochara kulunshanensis sp. nov., Porochara moyuensis sp. nov.)。这一化石组合不同于我国目前已知的晚二叠世轮藻类组合,而与欧洲同期轮藻类组合相近,可能反映了当时塔里木盆地与欧洲气候环境相近。文中还讨论了晚古生代末期轮藻类的演化关系,指出无顶孔的Paracuneatochara应起源于早二叠世早期或晚石炭世末期的Cuneatochara或与其性状相近的某属。     

Cymbella Agardh属(硅藻门Bacillariophyta)的一个新化石种的发现及其微细构造

新化石种Cymbella taicuonensis Li et Zheng sp.nov.是在研究西藏西北部日土县台错古湖剖面沉积物中硅藻植物群时发现的,剖面沉积物中保存了非常丰富的硅藻化石,Cymbella taicuonensis就是这些硅藻化石中的一个新化石种。对标本采用光学镜(LM)和扫描电镜(SEM)观察和照相,并对其微细构造进行深入的研究。     

西藏台错古湖晚第四纪轮藻类及其生态环境、气候变化探讨

西藏台错TT-1剖面厚369 cm,为一套碳酸盐粘土和粘土碳酸盐沉积,地层测年为41.4-4.5 ka,含丰富的轮藻化石,分属于11个轮藻植物群,群落所在地层的碳酸盐和钙质含量分别为80％和33％.从老到新(剖面自下而上):①41.4-26.64 ka(369-319 cm),处于末次冰期间冰阶MIS3a暖期,湖区气候...     

柴达木盆地北缘昆特依凹陷始新统下干柴沟组微体古生物研究

昆2井是柴达木盆地北部昆特依凹陷区潜伏Ⅰ号构造上的第一口勘探井,为了建立该地区地层层序,对该井的岩屑及岩芯样品进行了系统的微体古生物学研究,仅在下干柴沟组发现少量轮藻化石和零星的介形类化石。下干柴沟组下段出现的轮藻类Gyrogona qianjiangica和Lamprothamnium? brevis是我国中始新世最常见的化石。该层段的轮藻类可命名为Gyrogona qianjiangica-Lamprothamniumcurta-L. brevis组合,时代为中、晚始新世。本文以Gyrogona qianjiangica分布的顶、底界作为昆2井下干柴沟组下段的标志,划分结果与其它轮藻及介形类化石的对比结果基本一致。氯离子含量分布显示,轮藻类化石产出的下干柴沟组是整个地层剖面中含盐度最低的沉积阶段,表明下干柴沟组沉积时期,该地区处于水域比较广阔的淡水湖泊环境,但在个别层段出现咸化环境,产出以喜盐的Austrocypris为代表的介形类化石。     

我国南方泥盆纪轮藻类的新材料——兼论右旋和直立轮藻类藏卵器的定向和分类

中国南方泥盆纪已报道的轮藻化石有Sycidium、Chovanella 和Eochara 3属(卢衍豪,1948;王水、张善桢,1956;中国科学院南京地质古生物研究所,1974;王振,1976;张捷芳等,1978)。本文首次描述发现于云南的右旋轮藻类2属3种:Trochiliscus ingricus Karpinsky,T.zhanyiensis sp.nov.,Moellerina cf.convoluta(Peck)Peck et Morales,以及直立轮藻类的一个新类型——Pinnoputamen gen nov.。同时重新研究了曾被张捷芳等(1978)描述过的Sycidium的一个特别类型,命名为S.spinuliferum(sp.nov.)。     

陕西三叠纪轮藻化石

本文描述了产自陕西耀县、铜川、韩城地区三叠系的轮藻化石3亚科、4属、6种,其中包括1新属和3新种。在切片研究中,发现了Stellatochara 的底塞,从而对长期来有所争论的该属标本的定向问题提供了可靠的依据。陕西三叠纪轮藻化石的记述是亚洲地区三叠纪轮藻类的首次报道。     

新疆晚二叠世和三叠纪轮藻化石兼论古生代末期至中生代早期轮藻植物群的演变

一、前言 本文研究的晚二叠世轮藻化石,系卢辉楠1982—1983年在新疆北部考察时采获,三叠纪的材料产自南疆,系石油部新疆石油管理局勘探开发研究院古生物室提供。中三叠世轮藻类,在我国不少地区已被发现(王振、黄仁金,1978;张捷芳、卢辉楠等,1978;赵志清等,1980;王振,1981;张振来,1981;黄仁金,1983)。而晚二叠世和早三叠世轮藻类在国外报道的较少(Peck and Eyer,1963;1966b,1967,1968),晚二叠世轮藻类在我国最近才有报道(王振,1984),早三叠世仅个别种被报道(王振、黄仁金,1978)。     

古生代轮藻类的演化和分类

本文通过对古生代轮藻类群形态结构的比较研究,认为Ｔｒｏｃｈｉｌｉｓｃｕｓ和Ｍｏｅｌｌｅｒｉｎａ具有不同的起源。前者藏卵器包围细胞右旋具横脊,底部结构两侧对称,起源于Ｓｙｃｉｄｉｕｍ;后者的左旋轮藻类包围细胞简单,底部结构辐射对称源于具简单直立包围细胞的Ｘｉｎｊｉａｎｇｏｃｈａｒａ。根据底部结构的对称性,将轮藻门划分为Ｓｙｃｉｄｉｐｈｙｃｅａｅ和Ｃｈａｒｏｐｈｙｃｄｅａｅ两个纲,Ｓｙｃｉｄｉｐｈｙｃ     

山西轮藻属新植物

本文报道采自山西省的轮藻属植物2个新种,运城轮藻Chara yunchengensis,拟灰色轮藻C.pseudocanescens和3个中国新记录,阿尔泰轮藻C.altaica,豪威轮藻C.howeana,味美轮藻簇毛变种C.delicatula var.barbata     

准噶尔盆地南缘呼2井晚白垩世、古新世轮藻植物群的发现及其意义

准噶尔盆地南缘的露头剖面经过数十年的生物地层研究,一直未发现可靠的晚白垩世和古新世轮藻植物群。1995年,在准噶尔盆地南缘覆盖区的呼图壁背斜上钻探了呼2井,于井下3085-3588m井段发现了丰富的轮藻化石,其面貌迥异于地面所见的各轮藻组合。通过对该轮藻植物群的系统研究,发现其中含轮藻化石17属23种5比较种和3变种,包括1新种。根据各属种的时代分布,建立了两个组合：1．晚白垩世Chara tenuis-Horni-chara prolixa-Mesochar of．biacuta组合,大致相当于马斯特里赫特期;2．古新世Stephanochara cuneiformis-Grovesichara kielani-Sphaerochara nana组合。本文的研究成果完善了准噶尔盆地南缘的轮藻组合序列,同时也揭示了准噶尔盆地南缘凹陷区从边部向中心,随沉积条件的变化,地层层序趋于完整。     

巴尔干半岛现生轮藻植物综述

欧洲东南部巴尔干轮藻植物由于其产地生境的差异及以镶嵌状分布的模式,具有较高的生物分异度,计有44种,归属于现生属Nitella(10),Tolypella(4),Nitellopsis(1),Lychnothamnus(1),Lamprothamnium(1) and Chara(27).巴尔干半岛产有4种土著类型Chara rohlenae,Chara ohridana,Chara corfuensis and Chara visianii.建立1新种Chara hydropitys.该地区轮藻植物分布不均衡,部分类型例如Chara strigosa,Chara kokeilii,Chara muscosa,Chara fragifera,Chara imperfecta,Lychnothamnus barbatus为稀有品种,仅在少数地点发现.巴尔干地区轮藻植物之丰富多彩远远超过已知的程度,有待于深入研究.     

Biota, palaeoenvironments and biostratigraphy of continental Oligocene deposits of the South German Molasse Basin (Penzberg Syncline)

Six charophyte, 13 mollusc, four ostracod and nine fish otolith taxa are taxonomically described, and one fruit, one seed and two foraminiferal taxa are briefly noted from the Lower Cyrena Beds and the Lower Coloured Molasse of the Sindelsdorf section near Penzberg (approximately 50 km south of Munich). Our palaeoecological and lithological data from the Lower Cyrena Beds suggest a delta plain with lagoons, estuaries, slowly flowing rivers, lakes and swamps. Faunal and floral elements of the Lower Coloured Molasse indicate lacustrine environments. The gastropod Tympanotonos and the tropical to subtropical fish fauna (Eleotridae, Ambassidae and Cyprinodontidae) suggest a warm, at least subtropical climate. Furthermore, Tympanotonos suggests comparisons with Recent molluscan faunas of the mangrove swamps of the West African coast, and thus hints at mangrove vegetation bordering the coasts of the Upper Bavarian Molasse Sea. A biostratigraphical classification for the Oligocene Molasse deposits of the Penzberg Syncline is established for the first time based on otoliths and charophytes. The Lower Cyrena Beds are attributed to the newly defined otolith zone OT-O1/2 and probably correspond to the oldest part of the Chara microcera Zone. The lowermost part of the Lower Coloured Molasse can be correlated both with otolith zone OT-O2 and the Chara microcera Zone. The Sindelsdorf section lies within the Rupelian–Chattian transition zone and thus the chronostratigraphic age is approximately 29–28 Ma.     

苏北盆地高邮凹陷D1井白垩纪-古近纪微体古生物地层及沉积环境

高邮凹陷D1井富含介形虫、轮藻和孢粉等化石。通过系统的微体古生物分析,首次对该地区白垩纪一古近纪微体古生物地层进行了精确划分,从下到上共建立11个化石组合：其中介形虫4个,轮藻4个,孢粉3个。文中还简要探讨了沉积环境演变,为该地区油气勘探提供有力的生物地层依据。     

The seasonal effects on the encrustation of charophytes in two hard‐water lakes

Encrustation and element content of six charophyte species from two hard‐water lakes were investigated monthly for a period of 1 year. Seasonal patterns were analyzed for the interaction of water chemistry. Encrustation followed a seasonal pattern for Chara contraria, Chara subspinosa, and Nitellopsis obtusa in Lake Krüselin and for Chara globularis and Chara tomentosa in Lake Lützlow. However, no seasonality in the precipitated CaCO₃ was observed for C. subspinosa in Lake Lützlow and for C. tomentosa in Lake Krüselin, indicating a lake‐specific dependency. Species‐specific encrustation was found. Chara contraria and N. obtusa encrusted the most in June and August, whereas C. subspinosa and Nitella flexilis/opaca exhibited lowest encrustation in March and April. The precipitated CaCO₃ of charophytes correlated negatively to the concentration of total inorganic carbon in both lakes. Element content of plant dry weight was species‐specific for Ca and K, and lake‐specific for Mg. No specific pattern was found for the TP and Fe contents. The results showed seasonal, species, and lake‐specific influences on the encrustation of charophytes.     

Charophyten-Massenvorkommen aus den Oberen Pechelbronn-Schichten (Unteroligozän) von Merkwiller-Pechelbronn im Elsaß (Dépt. Bas-Rhin,Frankreich)

From the Upper Pechelbronn Formation (Latdorfian, Lower Oligocene) of Merkwiller-Pechelbronn (France, Alsace) a well preserved charophyte flora with numerous mass occurrences is presented. Two new species are described:Chara praemicrocera andSphaerochara pygmaea. The sequence seems to have been deposited under almost pure limnic conditions, according to ostracod data. Biostratigraphical correlations between the Upper Pechelbronn Formation, theStephanochara, pinguis zone (Riveline 1986) and the Mammalian reference level MP 21 (Schmidt-Kittler 1987) are postulated.     

Chara hispida beds as a sink of nitrogen: Evidence from growth,nitrogen uptake and decomposition

Chara hispida forms dense beds (0.78–0.95 kg DW m⁻²) in Colgada Lake. The ability of Chara meadows to act as a nitrogen source or sink was evaluated by the following methods: (1) investigating Chara growth, (2) nitrogen incorporation and decomposition laboratory experiments and (3) relating experimental results to field conditions. Sediment oospores were germinated in large aquaria and observed growth rates were 0.001 m day⁻¹ (shoot length) and 0.0002 g day⁻¹ (dry weight). Nitrogen uptake rates were determined by addition of K¹⁵NO₃ during two different periods of Chara growth and the rates were 1.21 and 3.86 μM g DW⁻¹ h⁻¹ when charophytes were 166 days old (not sexually mature) and 323 days old (sexually mature), respectively. After the uptake experiments, the same charophytes were allowed to decompose within two types of litter bags (3 mm-pore litter bags and entire, non-porous plastic litter bags). Decomposition rates of Ch. hispida were 0.016 and 0.009 day⁻¹ in perforated and non-perforated bags, respectively, and fit a negative exponential model. The nitrogen release rate, calculated as the disappearance of N content from Chara tissues, was 0.012 day⁻¹ and there were no statistically significant differences between the values from the two different bag types. The dissolved organic nitrogen concentrations in aquarium and non-perforated litter bags waters increased linearly with time due to the leaching of soluble compounds from Chara. The rate of N loss from Chara tissues, total nitrogen and dissolved organic nitrogen release rates and the decrease in initial dry weight rate were all lower than the daily rate of Chara N uptake. By extrapolating laboratory data to field situations, we determined that approximately 38% of the N taken up by charophytes in Colgada Lake during the growth period is retained. Given the high charophyte biomass in the lake, its ability to incorporate nitrogen, its low decomposition rate and its ability to over-winter, we conclude that Chara beds could be acting as nitrogen sinks in this ecosystem.     

Seasonal variation in invertebrate grazing on Chara connivens and C. tomentosa in Kõiguste Bay, NE Baltic Sea

Charophytes are a highly endangered group of algae. In the Baltic Sea, the number of species, distribution area and biomass of charophytes have significantly decreased in recent decades. Although eutrophication triggers their initial decline, the mechanism of the final extinction of charophyte populations is not fully understood. An in situ experiment was performed to study the role of the mesoherbivores Idotea baltica, Gammarus oceanicus and Palaemon adspersus in the decline of charophytes in the north-eastern Baltic Sea. Invertebrate grazing showed a clear seasonality: grazing pressure was low in April, moderate in July, and high in October. Grazing on charophytes by P. adspersus was negligible, whereas I. baltica and G. oceanicus significantly reduced the biomass of charophytes in the field. Low photosynthetic activity (high decomposition rate) of the charophytes favoured grazing. The invertebrates studied preferred Chara tomentosa to C. connivens. Low consumption of C. connivens may reflect its non-native origin. The experiment suggests that, under moderately eutrophic conditions, grazers are not likely to control charophyte populations. However, grazers have the potential to eliminate charophytes in severely eutrophic systems under the stress of filamentous algae.Communicated by H.D. Franke     

Mid to Late Holocene palaeoenvironment of Lake Eastern Juyanze (north-western China) based on ostracods and stable isotopes

An exposed section of nearly 13 m thick was investigated in the ancient depression of Lake Eastern Juyanze, north-eastern China. The succession of lacustrine and aeolian deposits covers a period from about 5400 to 2700 cal. a BP as indicated by four radiocarbon ages of macro-plant debris. Fifteen ostracod taxa were identified of which Limnocythere inopinata and Darwinula stevensoni are by far the most abundant species. Stable isotope (O, C) data of ostracod calcite as well as ostracod species abundances and X-ray diffraction results of bulk sediment samples were used to reconstruct the history of Lake Eastern Juyanze. Highest lake levels (water depth ∼10 m) occurred between 5100 and 4100 cal. a BP and were succeeded by intermediate and low levels until about 3150 cal. a BP. Three short-term events of complete desiccation were recorded between 3150 and 2900 cal. a BP. The lake experienced relatively high levels again for some decades at about 3000 cal. a BP and for at least two centuries after 2900 cal. a BP. According to the ostracod and gastropod record and the high abundance of a large diatom (Campylodiscus clypeus) in the lake sediments oligohaline to slightly mesohaline conditions were reconstructed for most of the lake periods (4-6 g/l). Geochemical and palaeontological records of Lake Eastern Juyanze reveal the retreat of the Asian monsoon after China’s Hypsithermal culminating in climate instability at about 3000 cal. a BP.     

Charophyten und Otolithen aus den Cyrenen-Schichten des nördlichen Alpenvorlandes

Charophytes and otoliths from theCyrena Beds of the northern Alpine foreland (Hausham and Miesbach synclines, Upper Bavaria) have been studied. A very abundant charophyte flora comprising 12 species, includingStephanochara martinii n. sp., is described and figured. The moderately diverse otolith fauna is documented by tables and SEM-pictures. The studiedCyrena Beds can be dated biostratigraphically as early Chattian and correlated with theChara microcera Zone. The charophytes show strong paleobiogeographic relations to floras in the Mainz Basin/Upper Rhine Graben as well as to western Switzerland and southern France. The otolith fauna is strikingly different from late Chattian faunas of the western Paratethys. The paleoecology indicated by charophytes, otoliths and the accompanying fauna suggests short term variation including freshwater, brackish water and marine influenced environments.