Encounters with an unearthly mudstone: Understanding the first mudstone found on Mars          下载免费PDF全文

Juergen Schieber  David Bish  Max Coleman  Mark Reed  Elisabeth M. Hausrath  John Cosgrove  Sanjeev Gupta  Michelle E. Minitti  Kenneth S. Edgett  Mike Malin 《Sedimentology》2017,64(2):311-358

The Sheepbed mudstone forms the base of the strata examined by the Curiosity rover in Gale Crater on Mars, and is the first bona fide mudstone known on another planet. From images and associated data, this contribution proposes a holistic interpretation of depositional regime, diagenesis and burial history. A lake basin probably received sediment pulses from alluvial fans. Bed cross‐sections show millimetre to centimetre‐scale layering due to distal pulses of fluvial sediment injections (fine‐grained hyperpycnites), fall‐out from river plumes, and some aeolian supply. Diagenetic features include mineralized synaeresis cracks and millimetre‐scale nodules, as well as stratiform cementation. Clay minerals were initially considered due to in situ alteration, but bulk rock chemistry and mineralogy suggests that sediments were derived from variably weathered source rocks that probably contained pre‐existing clay minerals. X‐ray diffraction analyses show contrasting clay mineralogy in closely spaced samples, consistent with at least partial detrital supply of clay minerals. A significant (ca 30 wt%) amorphous component is consistent with little post‐depositional alteration. Theoretical modelling of diagenetic reactions, as well as kinetic considerations, suggest that the bulk of diagenetic clay mineral formation occurred comparatively late in diagenesis. Diagenetic features (synaeresis cracks and nodules) were previously thought to reflect early diagenetic gas formation, but an alternative scenario of synaeresis crack formation via fabric collapse of flocculated clays appears more likely. The observed diagenetic features, such as solid nodules, hollow nodules, matrix cement and ‘raised ridges’ (synaeresis cracks) can be explained with progressive alteration of olivine/glass in conjunction with centrifugal and counter diffusion of reactive species. Anhydrite‐filled fractures in the Sheepbed mudstone occurred late in diagenesis when fluid pressures built up to exceed lithostatic pressure. Generating fluid overpressure by burial to facilitate hydraulic fracturing suggests a burial depth of at least 1000 m for the underlying strata that supplied these fluids.  相似文献   

A late Pleistocene and Holocene mineral magnetic record from sediments of Lake Aibi,Dzungarian Basin,NW China   总被引：1，自引：0，他引：1  

Alina Tudryn  Piotr Tucholka  Elisabeth Gibert  Francoise Gasse  Keiquin Wei 《Journal of Paleolimnology》2010,44(1):109-121

We studied mineral magnetic properties of a 6-m-long, late Pleistocene through Holocene sediment sequence from Lake Aibi in Dzungaria (Zunggary, Junggar), northern Xinjiang, China. Results were used to infer environmental changes and are compared with previously studied cores from Lake Manas. Both water bodies occupy the deepest parts of the Dzungarian Basin and are remnants of large Holocene lakes. During the Late Pleistocene, the magnetic mineralogy in both lakes was dominated by detrital, iron oxide minerals. Oxic conditions, which dominated during sedimentation and early diagenesis, persisted over the Pleistocene–Holocene transition. Later, during the middle Holocene, lake bottom conditions enabled authigenic formation of iron sulphide minerals such as pyrite (FeS₂) in Lake Aibi, and pyrite and greigite (Fe₃S₄) in Lake Manas. This iron sulphide mineralogy suggests increased biological activity in stagnant, anoxic bottom waters. Anoxic bottom conditions started about 9.8 cal kyr BP in Lake Manas and at about 7.2 cal kyr BP in Lake Aibi. A short dry event recorded in Lake Manas between 6.8 and 5.2 cal kyr BP is not clearly observed in Lake Aibi. In the late Holocene, i.e. the last 2.8 cal kyr, sediments of both lakes are again characterised by iron oxides, suggesting well-mixed, shallow water bodies. For this recent period, it seems that the detrital material in the two lakes had a common origin. Magnetic properties of sediments in Lakes Aibi and Manas show broadly similar environmental evolution during the late Pleistocene and Holocene. Nevertheless, despite the close proximity of the two lakes (~200 km) in the same basin, they display some different magnetic properties and record environmental changes at different times.  相似文献   

A comparison of annual and seasonal carbon dioxide effluxes between sub-Arctic Sweden and High-Arctic Svalbard     

Mats P. Björkman  Elke Morgner  Robert G. Björk  Elisabeth J. Cooper  Bo Elberling  & Leif Klemedtsson 《Polar research》2010,29(1):75-84

Recent climate change predictions suggest altered patterns of winter precipitation across the Arctic. It has been suggested that the presence, timing and quantity of snow all affect microbial activity, thus influencing CO₂ production in soil. In this study annual and seasonal emissions of CO₂ were estimated in High-Arctic Adventdalen, Svalbard, and sub-Arctic Latnjajaure, Sweden, using a new trace gas-based method to track real-time diffusion rates through the snow. Summer measurements from snow-free soils were made using a chamber-based method. Measurements were obtained from different snow regimes in order to evaluate the effect of snow depth on winter CO₂ effluxes. Total annual emissions of CO₂ from the sub-Arctic site (0.662–1.487 kg CO₂ m^–2 yr^–1) were found to be more than double the emissions from the High-Arctic site (0.369–0.591 kg CO₂ m^–2 yr^–1). There were no significant differences in winter effluxes between snow regimes or vegetation types, indicating that spatial variability in winter soil CO₂ effluxes are not directly linked to snow cover thickness or soil temperatures. Total winter emissions (0.004–0.248 kg CO₂ m^–2) were found to be in the lower range of those previously described in the literature. Winter emissions varied in their contribution to total annual production between 1 and 18%. Artificial snow drifts shortened the snow-free period by 2 weeks and decreased the annual CO₂ emission by up to 20%. This study suggests that future shifts in vegetation zones may increase soil respiration from Arctic tundra regions.  相似文献   

Norwegian school geography and geographical education: A new research field?     

Elisabeth Eikli 《Norsk geografisk tidsskrift. Norwegian journal of geography》2013,67(3):128-134

Despite having a long-standing relationship, teacher education and geography in primary and secondary education in Norway has received little attention as a research field within academic geography until recently. The author asks: How has Norwegian school geography related to geography taught at universities? Where does research on school geography and geographical education stand today and where should it go from here? She examines the development of the role played by academic geographers in the field from the 1970s until the present. Some potential future venues for this emerging research field are suggested on the basis of an examination of what themes are current focal points for research and comparing them to what other countries consider essential in their teacher education.  相似文献   

Energetic Charged Particles Above Thunderclouds     

Martin Füllekrug  Declan Diver  Jean-Louis Pinçon  Alan D. R. Phelps  Anne Bourdon  Christiane Helling  Elisabeth Blanc  Farideh Honary  R. Giles Harrison  Jean-André Sauvaud  Jean-Baptiste Renard  Mark Lester  Michael Rycroft  Mike Kosch  Richard B. Horne  Serge Soula  Stéphane Gaffet 《Surveys in Geophysics》2013,34(1):1-41

The French government has committed to launch the satellite TARANIS to study transient coupling processes between the Earth’s atmosphere and near-Earth space. The prime objective of TARANIS is to detect energetic charged particles and hard radiation emanating from thunderclouds. The British Nobel prize winner C.T.R. Wilson predicted lightning discharges from the top of thunderclouds into space almost a century ago. However, new experiments have only recently confirmed energetic discharge processes which transfer energy from the top of thunderclouds into the upper atmosphere and near-Earth space; they are now denoted as transient luminous events, terrestrial gamma-ray flashes and relativistic electron beams. This meeting report builds on the current state of scientific knowledge on the physics of plasmas in the laboratory and naturally occurring plasmas in the Earth’s atmosphere to propose areas of future research. The report specifically reflects presentations delivered by the members of a novel Franco-British collaboration during a meeting at the French Embassy in London held in November 2011. The scientific subjects of the report tackle ionization processes leading to electrical discharge processes, observations of transient luminous events, electromagnetic emissions, energetic charged particles and their impact on the Earth’s atmosphere. The importance of future research in this area for science and society, and towards spacecraft protection, is emphasized.  相似文献   

Characterisation of organic matter and microbial communities in contrasting arsenic-rich Holocene and arsenic-poor Pleistocene aquifers,Red River Delta,Vietnam     

Wafa M. Al Lawati  Athanasios Rizoulis  Elisabeth Eiche  Christopher Boothman  David A. Polya  Jonathan R. Lloyd  Michael Berg  Patricio Vasquez-Aguilar  Bart E. van Dongen 《Applied Geochemistry》2012

High concentrations of geogenic As in the groundwaters of south and SE Asia, which are used as drinking waters, are causing severe health impacts to the exposed human populations. It is widely accepted that As mobilisation from sediments into these shallow reducing groundwaters requires active metal-reducing microbes and electron donors such as organic matter (OM). Although OM in such Holocene aquifers has been characterised, there is a dearth of data on Pleistocene aquifers from the same areas. Reported here are preliminary studies of OM and microbial communities present in two aquifers, one of Pleistocene and one of Holocene age, with contrasting concentrations of As (viz. Pleistocene: low As <10 μg/L; Holocene: high As up to 600 μg/L) from Van Phuc village in the Red River Delta, Vietnam. Results revealed OM inputs from multiple sources, including potential contributions from naturally occurring petroleum seeping into the shallow aquifer sediments from deeper thermally mature source rocks. Although concentrations vary, no noticeable systematic differences in biomarker distribution patterns within the OM were observed between the two sites. Microbial analyses did not show a presence of microbial communities previously associated with As mobilisation. All clone libraries were dominated by α-, β-, and γ-Proteobacteria not known to be able to reduce Fe(III) or sorbed As(V). Furthermore, representatives of the Fe(III)-reducing genus Geobacter could only be detected at very low abundance by PCR, using highly selective 16S rRNA gene primers, supporting the hypothesis that metal reduction is not a dominant in situ process in these sediments. No correlation between As concentration in groundwater and OM composition nor microbial community in the host sediments was found. This suggests that either (i) As is not being significantly mobilised in situ in these sediments, instead As appears to be mobilised elsewhere and transported by groundwater flow to the sites or (ii) sorption/desorption processes, as implicated by geochemical data from the cores, play a critical role in controlling As concentrations at these sites.  相似文献   

Integrated Water Resources Management under different hydrological,climatic and socio-economic conditions   总被引：2，自引：2，他引：0  

Edda Kalbus  Thomas Kalbacher  Olaf Kolditz  Elisabeth Krüger  Jörg Seegert  Gunda Röstel  Georg Teutsch  Dietrich Borchardt  Peter Krebs 《Environmental Earth Sciences》2012,65(5):1363-1366

  相似文献   

Silver fluxes to the Gironde Estuary - Eleven years (1999-2009) of monitoring at the watershed scale     

Laurent LanceleurJörg Schäfer  Cécile BossyAlexandra Coynel  Aurélie LarroseMatthieu Masson  Gérard Blanc 《Applied Geochemistry》2011,26(5):797-808

Although Ag has long been recognized as highly toxic to aquatic organisms and as an efficient tracer of urban wastewater inputs, there are very few data available on Ag levels and fluxes in rivers and estuaries. Due to anomalously high Ag concentrations in oysters from the estuary mouth, dissolved (Ag_D) and particulate Ag (Ag_P) concentrations in rivers of the Gironde Estuary watershed were studied. Using daily discharge, Suspended particulate matter (SPM) data and monthly measured Ag_D and Ag_P, the respective fluxes were estimated at the three main entries of the Gironde Estuary and at selected key sites at the outlets of different sub-watersheds for multiple years of the past decade. Dissolved and particulate Ag concentrations were 0.5 ng/L (detection limit) to 5.7 ng/L and 0.13-13.9 mg/kg in all rivers, except for the Riou-Mort River (up to 1260 ng/L and 261 mg/kg) that has been heavily polluted by former Zn ore treatment and remaining waste tailings. At all sites Ag transport mainly (73-100%) occurred in the particulate phase, i.e. strongly depended on hydrological parameters. Comparing Th-normalised (i.e. grain size independent) Ag_P levels at the different sites including one remote site showed that the regional background is best described by Ag_P/Th_P = 0.026. The anthropogenic components in Ag_P levels and fluxes ranged from 24% to 90% at all sites, except for the Riou-Mort River (81-99%). Although this former ore treatment site still is an evident Ag source to the Lot-Garonne fluvial-estuarine system, its contribution to Ag fluxes at the main entry of the Gironde Estuary (i.e. 0.33-2.44 t/a at the La Reole site) is <11%. This clearly suggests that other sources such as rock weathering and erosion (0.057-0.817 t/a), urban wastewater inputs (0.042-0.057 t/a) and cloud-seeding (0.030-0.063 t/a) contribute the major parts of the fluvial Ag budget in this watershed. The estimated anthropogenic surface- and population-specific Ag fluxes in the studied system were 1.14-682 g/km²/a and 0.028-6.05 g/person/a, respectively. The results obtained suggest that the Gironde fluvial-estuarine system is contaminated by Ag inputs from various sources, but further work is necessary to (i) identify and quantify the major sources and (ii) produce comparable data for other systems, which would be useful for the evaluation of Ag contamination at a larger scale.  相似文献   

Impact of the 11 March 2011, Great East Japan earthquake and tsunami on the chemical industry     

Elisabeth Krausmann  Ana Maria Cruz 《Natural Hazards》2013,67(2):811-828

The Great East Japan earthquake and tsunami damaged or destroyed many industrial facilities housing or processing hazardous substances, such as refineries, petrochemical facilities and other types of chemical industry. This showed that also generally well prepared countries are at risk of suffering natural hazard triggered technological (Natech) accidents. An analysis of data collected from open sources and through interviews with authorities was performed to understand the main reasons for the industrial damage and downtime as well as the extent of hazardous-materials releases and the associated impact on society. The analysis of the data set confirmed the findings from other studies with respect to main damage and failure modes, as well as hazardous-materials release paths. In addition, gaps in Natech risk management were identified. Based on the data analysis and interviews lessons learned in support of a more far-reaching Natech risk management are presented.  相似文献   

Recent Results from Studies of Electric Discharges in the Mesosphere   总被引：3，自引：3，他引：0  

T. Neubert  M. Rycroft  T. Farges  E. Blanc  O. Chanrion  E. Arnone  A. Odzimek  N. Arnold  C.-F. Enell  E. Turunen  T. Bösinger  Á. Mika  C. Haldoupis  R. J. Steiner  O. van der Velde  S. Soula  P. Berg  F. Boberg  P. Thejll  B. Christiansen  M. Ignaccolo  M. Füllekrug  P. T. Verronen  J. Montanya  N. Crosby 《Surveys in Geophysics》2008,29(2):71-137

The paper reviews recent advances in studies of electric discharges in the stratosphere and mesosphere above thunderstorms, and their effects on the atmosphere. The primary focus is on the sprite discharge occurring in the mesosphere, which is the most commonly observed high altitude discharge by imaging cameras from the ground, but effects on the upper atmosphere by electromagnetic radiation from lightning are also considered. During the past few years, co-ordinated observations over Southern Europe have been made of a wide range of parameters related to sprites and their causative thunderstorms. Observations have been complemented by the modelling of processes ranging from the electric discharge to perturbations of trace gas concentrations in the upper atmosphere. Observations point to significant energy deposition by sprites in the neutral atmosphere as observed by infrasound waves detected at up to 1000 km distance, whereas elves and lightning have been shown significantly to affect ionization and heating of the lower ionosphere/mesosphere. Studies of the thunderstorm systems powering high altitude discharges show the important role of intracloud (IC) lightning in sprite generation as seen by the first simultaneous observations of IC activity, sprite activity and broadband, electromagnetic radiation in the VLF range. Simulations of sprite ignition suggest that, under certain conditions, energetic electrons in the runaway regime are generated in streamer discharges. Such electrons may be the source of X- and Gamma-rays observed in lightning, thunderstorms and the so-called Terrestrial Gamma-ray Flashes (TGFs) observed from space over thunderstorm regions. Model estimates of sprite perturbations to the global atmospheric electric circuit, trace gas concentrations and atmospheric dynamics suggest significant local perturbations, and possibly significant meso-scale effects, but negligible global effects.  相似文献