Integrated chemostratigraphy and biostratigraphy of the Windermere Supergroup, northwestern Canada: implications for Neoproterozoic correlations and the early evolution of animals

The thick, richly fossiliferous succession of the upper Windermere Supergroup, Mackenzie Mountains, northwestern Canada, provides a test of integrated biostratigraphic and chemostratigraphic frameworks in terminal Proterozoic correlation. The C- and Sr-isotopic abundances of lower Keele Formation carbonates approximate those for other pre-Varanger samples, confirming that the simple disc-like fossils of the underlying Twitya Formation predate all known diverse Ediacaran faunas. "Tepee" and Sheepbed carbonates record strong post-glacial isotopic excursions; in contrast, delta13C values for Gametrail through Risky carbonates vary only within the narrow range of about +l% to +2%. A second negative excursion occurs in Ingta Formation carbonates that immediately underlie the paleontologically determined Precambrian-Cambrian boundary. The upper Windermere profile as a whole compares closely with curves determined for other terminal Proterozoic successions. The lowermost diverse Ediacaran assemblages in the Sheepbed Formation correlate chemostratigraphically with the oldest fauna in Namibia, but the two assemblages differ in taxonomic composition. Blueflower assemblages correlate both chemostratigraphically and taxonomically with faunas from Australia, China, Siberia, and elsewhere. Increasing data support the hypothesis that paleontological and geochemical data together provide a reliable means of correlating terminal Proterozoic sedimentary rocks throughout the world.     

Spatial variation of nutrients and primary productivity in the Rufiji Delta mangroves,Tanzania

Determinations of spatial and temporal variations in organic matter and nutrient dynamics in water and sediments are crucial for understanding changes in aquatic bodies. In this study, we (i) determine the spatial dynamics of dissolved inorganic nutrients, during the transition from the dry to the rainy season, and (ii) provide future productivity predictions for the Rufiji Delta mangroves, Tanzania, based on the input of various nutrients. Water samples were collected from six locations, three times per year between April 2012 and January 2014, and analysed for dissolved nutrients, total organic and inorganic carbon, chlorophyll a, chlorophyll b and total carotenoids. The prediction of future net primary productivity in the Rufiji mangroves was undertaken using the software STELLA. The mean nutrient concentrations were of the order: nitrate > phosphate > ammonium > silica > dissolved organic carbon. The study revealed that high nutrient concentrations occurred in the northern part of the Rufiji Delta as a result of anthropogenic influence in the watershed. Modelling of nutrient inputs into the delta indicated enhanced primary productivity, which is expected to increase the vulnerability of water quality in the near future due to eutrophication.     

PILOT: a balloon-borne experiment to measure the polarized FIR emission of dust grains in the interstellar medium

Future cosmology space missions will concentrate on measuring the polarization of the Cosmic Microwave Background, which potentially carries invaluable information about the earliest phases of the evolution of our universe. Such ambitious projects will ultimately be limited by the sensitivity of the instrument and by the accuracy at which polarized foreground emission from our own Galaxy can be subtracted out. We present the PILOT balloon project, which aims at characterizing one of these foreground sources, the polarized continuum emission by dust in the diffuse interstellar medium. The PILOT experiment also constitutes a test-bed for using multiplexed bolometer arrays for polarization measurements. This paper presents the instrument and its expected performances. Performance measured during ground calibrations of the instrument and in flight will be described in a forthcoming paper.     

Polycyclic aromatic hydrocarbon (PAH) burden of mussels (Mytilus sp.) in different marine environments in relation with sediment PAH contamination, and bioavailability

Sediments and mussels (Mytilus edulis, Mytilus galloprovincialis) were sampled in different European coastal environments (Germany, France, Spain) and analysed for their polycyclic aromatic hydrocarbon (PAH) content by Gas Chromatography/Mass Spectrometry (GC-MS). Bioaccumulation factors of individual compounds from the sediment were calculated and discussed according to the compound solubility. The mussels showed different accumulation patterns according to the pollution source they were exposed to (dissolved fraction of PAHs, particulate fraction, petroleum present in the water column). The exposure source also depends on the geographical location of the mussels. In the Mediterranean Sea, the bivalves were mainly exposed to the dissolved fraction of PAHs, while in the Baltic Sea and in the Atlantic Ocean, the PAHs associated to the particles were significant sources.     

湖北铜绿山矿床石英闪长岩的矿物学及Sr-Nd-Pb同位素特征

铜绿山是长江中下游鄂东南矿集区最重要的、大型夕卡岩型Cu-Fe(Au)矿床。本文对该矿区中与成矿密切的石英闪长岩进行了详细的矿物成分、地球化学及Sr-Nd-Pb同位素研究。结果表明:岩石中斜长石主要为更长石(An=21～31);角闪石贫Ti(0.2),高Mg/(Mg+Fe)(0.5),属于富镁角闪石;而黑云母为镁质黑云母。岩石的地球化学具有高硅(58.86%～67.71%),富碱(Na2O+K2O=5.67%～9.63%),富集轻稀土元素(LREE)和大离子亲石元素(LILE),并强亏损元素Nb、Ta、Ti等特征。岩石的(87Sr/86Sr)i为0.7055～0.7069,εNd(t)为-7.65～-3.44;(206Pb/204Pb)i=17.66～18.00,(207Pb/204Pb)i=15.49～15.56,(208Pb/204Pb)i=37.73～38.19。矿物成分、地球化学和同位素特征说明,铜绿山岩体与阳新岩体为同源岩浆的产物,源区为深度大于40km的富集地幔,经下地壳的混染及分离结晶作用形成。岩浆熔体形成的温度应大于889℃。角闪石和黑云母的温度计估算岩浆结晶温度分别为650～800℃和500～630℃,黑云母开始结晶温度略低于角闪石结晶结束温度,压力为1.49kbar,对应侵位深度约4.9km。岩浆具有利于Cu、Fe、Au等成矿元素进入熔体的条件,可能与板块俯冲作用相关。     

Pigmenting agents in Martian soils: inferences from spectral, Mossbauer, and magnetic properties of nanophase and other iron oxides in Hawaiian palagonitic soil PN-9

We have examined a Hawaiian palagonitic tephra sample (PN-9) that has spectroscopic similarities to Martian bright regions using a number of analytical techniques, including Mossbauer and reflectance spectroscopy, X-ray diffraction, instrumental neutron activation analysis, electron probe microanalysis, transmission electron microscopy, and dithionite-citrate-bicarbonate extraction. Chemically, PN-9 has a Hawaiitic composition with alkali (and presumably silica) loss resulting from leaching by meteoric water during palagonitization; no Ce anomaly is present in the REE pattern. Mineralogically, our results show that nanophase ferric oxide (np-Ox) particles (either nanophase hematite (np-Hm) or a mixture of ferrihydrite and np-Hm) are responsible for the distinctive ferric doublet and visible-wavelength ferric absorption edge observed in Mossbauer and reflectivity spectra, respectively, for this and other spectrally similar palagonitic samples. The np-Ox particles appear to be imbedded in a hydrated aluminosilicate matrix material; no evidence was found for phyllosilicates. Other iron-bearing phases observed are titanomagnetite, which accounts for the magnetic nature of the sample; olivine; pyroxene; and glass. By analogy, np-Ox is likely the primary pigmenting agent of the bright soils and dust of Mars.     

Biochemical and histological responses in mussel (Mytilus edulis) exposed to North Sea oil and to a mixture of North Sea oil and alkylphenols

Several environmental chemicals are suspected to be responsible for adverse health effects on the reproductive system in various organisms. During this work, environmentally relevant concentrations of North Sea oil were used alone or in combination with alkylphenols and additional PAH to study the effect on vitellogenin-like protein expression and gonadal development in mussels. North Sea oil (0.5 ppm) induced the expression of phospho-proteins in both sexes indicating that some compounds are oestrogen-mimics. This induction was not seen in samples dosed with the mixture but signs of toxic effects were observed in the gonads. Indeed, numerous degenerating ovarian follicles in females and foci, similar to vertebrate melanomacrophage centres, were observed in testes.     

Competition in a Precambrian world: palaeoecology of Ediacaran fronds

Leaf‐shaped Ediacaran fronds are among the most widespread and readily recognized members of the terminal Neoproterozoic Ediacara Biota. Ediacaran fronds gathered nutrients from the water column through filter feeding or direct nutrient absorption, resulting in the onset of modern‐style ecological competition complete with denizens occupying distinct tiers in the water column. It is believed that the frond shape most likely represents a common need to elevate a feeding apparatus higher in the water‐column to feed from the upper (> 20 cm) tiers. Therefore, the frond shape represents a shared ecology, not ancestry.     

敦煌三危山地区白垩纪OIB型基性岩墙的特征及地质意义

本文首次报道甘肃敦煌三危山地区早白垩世玄武质岩浆活动的记录。在三危山附近,基性岩墙侵入于敦煌群TTG和表壳岩大理岩和片岩中。全岩的K-Ar年龄为136.00±11.56Ma到99.11±6.35Ma,形成时代属于早白垩世。基性岩墙SiO₂含量变化范围较小,集中在47.95%~50.65%之间,以富TiO₂ (2.07%~2.35%,平均为2.21%)、MgO(6.03 %~6.51%,平均为6.32%)、贫K₂O(<1.29%),Na₂O>K₂O, Mg^#值中等且比较稳定(48.9~53.1,平均为51.7)为特征。基性岩相容元素含量相对较低,Ni含量变化相对较小,分布在112.7×10^-6~182.7×10^-6之间。而V含量变化较大,介于184×10^-6~267×10^-6之间,表明岩浆早期可能发生了一定的以橄榄石和单斜辉石为主的分离结晶作用。基性岩富集LREE((La/Yb)_N ＝3.97~4.66)和LILE,无Eu负异常,较高的Fe/Mn比值等,具有与洋岛玄武岩(OIB)相似的特征。微量元素比值等特征表明其来源与富集地幔关系密切,玄武质岩浆的形成可能与岩石圈的减薄和软流圈的上涌有关。