西秦岭关家沟组晚奥陶世苔藓植物孢子和陆生维管束植物小孢子化石

西秦岭文县东峪口—关家沟一带分布的关家沟组为一套粗碎屑流和浊流沉积组合,因缺乏古生物化石,其形成时代长期存在争议。在文县关家沟滴水岩剖面中、下部4件灰色粉砂质板岩样品中分离并鉴定出了晚奥陶世苔藓植物孢子(隐孢子)(cryptospores)和陆生维管束植物小孢子(miospores)化石8属18种(包括未定种)、疑源类(acritarchs)8属10种、几丁虫(chitinozoa)3属4种和虫颚(scolecodonts)3属3种,这些微体化石的地质时代相当于西欧Carodoc-Ashgill阶。在这些样品中发现苔藓植物孢子和早期陆生维管束植物小孢子,不仅是中国奥陶纪地层中首次发现和报道,而且也为研究早期陆生植物演化提供新的直接依据。     

西昆仑叶城南部麻扎地区志留纪几丁虫动物群新发现

西昆仑地区处于中亚腹地的高寒缺氧地带，区域地质研究程度较低。早志留世轻变质碎屑岩地层时代的确定主要依据三叶虫、头足类和珊瑚等大化石，一直没有微体化石方面的证据。最近，在西昆仑地区进行的地质调查中，在温泉沟地区新发现了较丰富的志留纪Desmochitina，Sphaerochitina，Rhabdochitina，Conochitina等属几丁虫化石，为早志留世碎屑岩地层时代的确定、西昆仑地区地质调查工作的开展、志留纪地层的划分对比和西昆仑地区地质演化历史的研究提供了重要微体化石方面的依据。     

河南信阳群南湾组化石孢子的发现及其地质意义

作者在河南信阳附近信阳群南湾组中、上部的轻变质灰色砂板岩中发现了丰富的孢子,此外还有疑源类(Acritarchs),几丁虫(Chitinozoans)和虫颚(Scolecedonts)化石。该孢子组合可与华南和西秦岭中泥盆世晚期和晚泥盆世早期孢子组合比较,亦可与西欧、北美和苏联中泥盆世晚期季维特阶(Givetian)和晚泥盆世早期弗拉斯阶(Frasnian)比较,其时代为中泥盆世晚期至晚泥盆世早期。 信阳群南湾组微体化石的发现不仅解决了长期争论的信阳群南湾组的时代问题,而且对秦岭和大别山构造带的区域地质调查和构造带的演化研究都具有重要意义。     

安徽霍邱安阳山晚石炭世碳酸盐岩地层中奥陶纪牙形石和虫颚化石的发现

最近的研究表明,安徽霍邱地区安阳山(白大山)剖面下部碳酸盐岩段属于晚石炭世,上部碎屑岩段属于青白口纪。我们进一步对剖面进行了微体古生物分析,在晚石炭世碳酸盐岩中发现了丰富的微体古生物化石,其中以牙形石和虫颚化石数量最多。经鉴定,有牙形石Belodina和虫颚化石Marlenites marginatus,Chairidogenys borealis,Cornugenys sp.,Porrhogrnys sp.,Channahania sp.,Paradrilonersgenys cherylae等,Belodina时代为晚奥陶世,虫颚化石的时代为奥陶纪。晚石炭世地层中存在奥陶纪化石,表明可能存在奥陶系的物源区,微体化石是通过剥蚀、搬运再沉积保存到晚石炭世碳酸盐岩中。显然,新发现的微体化石可能并不具有地层意义,但是具有古地理和古构造意义。     

浙江早古生代孢粉型化石的研究

在浙江西北部早寒武世荷塘组、晚寒武世华严寺组、早奥陶世宁国组、晚奥陶世长坞组和文昌组、早志留世霞乡组、河沥溪组和康山组、中志留世唐家坞组中发现孢粉型化石,孢粉型化石包括疑源类,隐花(陆生)植物孢子类型等,计66属、112种、31未定种。同时讨论了这9个层位孢粉型化石的组合特征、地质时代及其沉积环境。     

湖北房县梅花山志留系微体植物化石新发现及地层意义

文章报道了在湖产房县梅花山一带山露的一套浅变质地层中首次发现较多的微体植物化石，据其组合特征及区域对比，大致确定了它的形成时代为早志留世。这些发现不但丰富了该区志留纪古生物资料，而且为其时代归属提供了较可靠的依据。     

西准噶尔晚志留世、早泥盆世孢子和疑源类

新疆西准噶尔沙尔布尔提山晚志留世、早泥盆世孢子和疑源类包括孢子21属31种和变种,其中新种1个(Amicosporites xinjiangensis);疑源类11属14种。此外还有几丁虫3属3种。根据孢子在地层中分布规律和演化特征,自下而上可划出4个孢子带:1.Synorisporites dittonensis—Api-culiretusispora spicula(DS)带;2.Emphanisporites micrornatus—Streelispora newportensis(MN)带;3.Chelinospora cassicula—Perotriletes subitus(CS)带;4.Grandispora sp.—Apiculatasporites micro-conus(CM)带;上述孢子组合基本上可与中国华南、西南、西秦岭及有关国家、地区相同时代孢子带对比。根据孢子和疑源类材料,对西准噶尔志留—泥盆系界线、古地理和古生态进行了讨论。     

甘肃漳县王家店组孢子组合及其时代

本文首次报道甘肃漳县大草滩王家店组发现的丰富的化石孢子研究结果。在王家店组除孢子外,还发现少量疑源类(Acritarchs)和虫颚化石(Scole-codonts)。本文图示14个孢子属,23种和变种(包括未定种),根据孢子在地层中分布规律和演化特征,自下而上可划分为两个孢子带,下带称Retispora lepido-phyta-Knoxisporites literatus(LL)带,上带称Retispora lepidophyta-Hymenozonotrletes explanatus(LE)带。 甘肃漳县大草滩王家店组孢子带可以与华南和西藏珠穆朗玛峰地区的孢子带比较,同时可与西欧(Clayton et al,Higgs et al. ,1987)晚泥盆世晚期的Retis-pora lepidophyta-Knoxisporites literatus(LL)带和Retispora lepidophyta-Hymenozonotriletes explanatus(LE)带比较,时代为晚泥盆世晚期斯特隆阶(Strunian)早中期。     

海南岛西部“军营群”发现志留纪微古植物化石

笔者在海南岛西部军营地区,原划归石炭—二叠纪的军营群下部首次发现志留纪微古植物化石:Lsiopsophosphaera,Trachysphaeridium,Baltisphaeridium等,上部新发现石炭纪腕足类化石:Rugosochonetes cf.hararensis(Phillips)等。通过对比,废弃了“军营群”一名,认为其下部相当于陀烈群,时代为早—中志留世,上部相当于青天峡组,时代归属石炭纪。     

河南西峡地区二郎坪群火神庙组中发现泥盆纪孢子化石

在河南省西峡地区二郎坪群火神庙组粉砂质板岩中发现丰富的陆生植物孢子(Spores)、少数疑源类(Acritarchs)和极少数几丁虫(Chitinozoa)化石.该化石孢子组合可与中国华南、西南地区和西秦岭中泥盆世早期孢子组合比较,亦可与西欧和北美中泥盆世早期的孢子带比较,时代为中泥盆世,并有可能为中泥盆世早期,相当于西欧艾菲尔期(Eifelian).     

On the origin of the “kleine Kügelchen” called Chondrules

In this paper we investigate two major issues: (1) What are chondrules, and (2) why do they exist? We review the literature pertaining to each question and explore answers. We discuss the diversity of chondrules, especially with regard to their igneous textures and compositions. We review the constraints that have been placed experimentally on the thermal histories of chondrules and list those fundamental properties that all chondrule formation models must explain quantitatively in order to be considered predictive, quantitative models. We provide background on the three major classes of chondrule formation models currently being discussed, and scrutinize each with respect to how well they adhere to the experimental constraints placed on chondrule formation. Finally, we list several unresolved issues that are now or will soon be at the forefront of chondrule research.     

Lucinid clam influence on the biogeochemistry of the seagrass<Emphasis Type="Italic">Thalassia testudinum</Emphasis> sediments

Lucinid bivalves dominate the infauna of tropical seagrass sediments. While the effect of seagrass on lucinids has been studied, the reverse effect has largely been ignored. Lucinids can alter porewater chemistry (i.e., increase porewater nutrients by suspension feeding and decrease porewater sulfides by oxygen introduction and bacterial oxidation), which can potentially change seagrass productivity and growth morphology. To observe correlations between porewater chemistry and lucinid presence, a field survey and laboratory microcosm experiment were conducted. Survey sampling sites with lucinids had significantly lower sulfide and higher ammonium concentrations than sampling sites without lucinids. There was no difference in phosphate concentration among sampling sites. Both lucinid species used in the microcosm experiment (Ctena orbiculata andLucinesca nassula) significantly lowered sulfide concentrations in the sediment porewater. Microcosm and field survey results were incorporated into a sulfide budget. In seagrass sediments, lucinids remove 2–16% of the total sulfide produced. Sulfide is a major stressor to both plants and animals in Florida Bay sediments; this removal may be important to maintaining seagrass productivity and health. Oxygen introduction into sediments byC. orbiculata was estimated in a dye experiment.C. orbiculata were added to small tubes containing sieved mud and incubated in a bath of seawater with a Rhodamine WT. Rhodamine WT accumulation in the sediment was measured. A first order estimate showed that oxygen introduction can account for less than 5% ofC. orbiculata sulfide removal.     

Simulation of the molecular mass distributions of Si anions on the liquidus of the Na<Subscript>2</Subscript>O-SiO<Subscript>2</Subscript> system with regard for the disproportionation of <Emphasis Type="Italic">Q</Emphasis> structons

A new version of the STRUCTON (2009) computer model is proposed for the simulation of the molecular mass distributions (MMD) characterizing the diversity of anions in silicate melts depending on their polymerization and temperature. In contrast to earlier versions, the new version of the model accounts for disproportionation reactions of Q ⁿ species and makes use of their proportions in the statistical simulations of the origin of real Si-O complexes. The new potentialities of the STRUCTON program package are illustrated by its application to studying the structural-chemical characteristics of melts in the Na₂O-SiO₂ system along its liquidus line, including the points of eutectics and phase transitions at 0.333 ≤ $ N_{SiO_2 } $ N_{SiO_2 } < 0.500. This problem is solved with the use of a temperature-composition dependence of polymerization constants K _p ^Na in the Toop-Samis approximation. The variations in K _p ^Na were proved to be as large as three orders of magnitude due to both the temperature effect at a constant composition and the composition effect at a constant temperature. The results of the MMD simulations on the liquidus show that the concentration of the SiO₄⁴⁻ ion strongly decreases, and the proportion of chain species increases compared to those at a stochastic distribution. The concentration of the Si₂O₇⁶⁻ anion reaches its maximum (∼42%) at 40 mol % in the liquid, i.e., the composition of Na₆Si₂O₇. At $ N_{SiO_2 } $ N_{SiO_2 } > 0.40, this ion dominates over the SiO₄⁴⁻ monomer. More silicic melts with $ N_{SiO_2 } $ N_{SiO_2 } ≥ 0.45, are dominated by (Si _n O_3n )³ⁿ⁻ ring species, and the concentrations of these species are related as (Si₃O₉)⁶⁻ > (Si₄O₁₂)⁸⁻ > (Si₅O₁₅)¹⁰⁻. The maximum concentration of these flat rings also occurs near the composition of stoichiometric metasilicate with Si/O = 0.333. The comparison of the dependence of the average size of anions i _av and the average number of their species on depolymerization indicates that a change in the proportion of Q ⁿ species in melt at decreasing temperature results in structural restyling and an increase in the average size of Si-O complexes. The average number of anion species thereby decreases compared to that in a stochastic MMD. The results presented in this publication direct the progress in the thermodynamic theory of silicate melts to a new avenue that makes use of the capabilities and advantages of the ion-polymer model, the theory of associated solutions, spectroscopic data, and the experimental study of variations in oxide activities depending on composition and temperature.     

<Emphasis>H</Emphasis>ydrological variability of the <Emphasis>S</Emphasis>oummam watershed <Emphasis>(N</Emphasis>ortheastern <Emphasis>A</Emphasis>lgeria<Emphasis>)</Emphasis> and the possible links to climate fluctuations

The long-term variability of rainfall in the Soummam watershed (NE Algeria) has been analysed over the past 108 years using continuous wavelet method in order to identify the interannual modes controlling the rainfall variability. Statistical analyses of rainfall timeseries have shown its distribution following five periods of time, limited by a series of discontinuities around 1935, 1950, 1970 and 1990. The continuous wavelet transform have demonstrated different low frequency modes: 2–4, 4–8, 8–16 and 16–32 years.The annual band is expanded during the full study period with some pics around 1905, 1920–1935 and 1960; it shows a negative long-term trend, in particular since the period 1970–1990 when a major change has been identified. Then, the relationships between climate patterns of North Atlantic Oscillation (NAO) and Southern Oscillation Index (SOI) and the hydrological variability in the frequency domain have been investigated; they have shown a mean explained variance of 40 and 24 %, respectively. Such variances are less obvious for the annual mode and increase for the interannual frequencies. The coherence suffer from high perturbations since the period 1970–1990 when the NAO (SOI) shifts from negative (positive) phases to positive (negative) ones. Such anomalies are responsible for significant changes of rainfall variability, emphasising the global warming effects.     

Characterisation of the antiferromagnetic transition of Cu<Subscript>2</Subscript>FeSnS<Subscript>4</Subscript>, the synthetic analogue of stannite

Magnetisation measurements were performed on the synthetic analogue of stannite, Cu₂FeSnS₄, in order to characterise the antiferromagnetic transition at low temperature, evidenced by Bernardini et al. (2000). Temperature and field dependence of the material were checked by means of static magnetisation measurements, carried out scanning the magnetic fields up to 12 T and temperatures in the range 1.4–20 K, while ac susceptibility data were collected at different frequencies ranging from 1.8 to 510 Hz. Both static and dynamic magnetisation data, performed above and below the Néel temperature, 6.1(2) K, confirm stannite to order antiferromagnetically at a long-range scale. Moreover, an increase of both the magnetic anisotropy and the exchange interaction, with respect to the Mn-analogue (Fries et al. 1997), has been observed.     

<Emphasis Type="Italic">An Inconvenient Truth</Emphasis> and the scientists

An Inconvenient Truth provides an opportunity to examine the differences between scientific statements and the mixed statements made by politicians. The Gore movie is a powerful example of the latter. There are some inaccuracies and exaggerations in the film, but on the whole it represents mainstream scientific views on global warming. This essay looks into the state of the art of climate change research including its scientific underpinnings. Climate science is in a state of ‘normal science’ as discussed by Kuhn. There is a large body of scientists who are adherents to the paradigm and there does not appear to be any serious alternative at this time.     

<Emphasis Type="Italic">An Inconvenient Truth</Emphasis>: the scientific argument

The movie An Inconvenient Truth is a powerful portrayal of global warming and its impacts. The main scientific argument presented in the movie is for the most part consistent with the weight of scientific evidence, but with some of the main points needing updating, correction, or qualification. The detailed argument relies almost entirely on past and current evidence and neglects almost all information that can be gained from computer models, perhaps because such information would be difficult for a lay audience to grasp, believe, or connect with emotionally. This places an undue weight on current events as signs of ongoing climate change: some such events are apparently not related at all to climate change, while for other specific events the role of global warming is difficult or impossible to establish.