Lower Cretaceous micropalaeontology of the Fastnet Basin, offshore south-west Ireland     

Nigel R. Ainsworth  Nicola F. Horton  Randall A. Penney 《Marine and Petroleum Geology》1985,2(4):341-349

The Lower Cretaceous sediments of the Fastnet Basin display similarities to the succession in Britain. The continental Wealden facies is succeeded by a series of marine and marginal marine sediments which reflect the transgression which culminated in the Cenomanian as the chalk seas of the Upper Cretaceous. Some of the changes seen within the microfaunas and microfloras through the Lower Cretaceous are a reflection of the transient facies, and are diachronous across the basin. The microfaunal and palynological associations are described, and the approximate age of each association is based on species ranges reported from onshore Europe and Britain.In some areas, there were local differences in the micropalaeontological associations, in particular in the early Aptian to the late Barremian of well 63/10-1.  相似文献   

Fine Sediment Dynamics in the Marine Environment: J.C. Winterwerp and C. Kranenburg; Elsevier, Amsterdam, 2002, 713 pages, Euro 189.00, ISBN 0-444-51136-9     

Nigel Pontee 《Estuarine, Coastal and Shelf Science》2003,57(5-6):1200-1201

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Is Bangkok at risk of marine flooding? Evidence relating to the historical floods of AD 1785 and 1983     

Terry  James P.  Winspear  Nigel  Goff  James 《Natural Hazards》2021,105(1):1013-1030

Natural Hazards - Thailand’s low-lying capital city Bangkok is a dense metropolis, one of Asia’s rapidly growing ‘megacities’, and home to over 10 million...  相似文献   

A Synthetic Haematite Reference Material for LA‐ICP‐MS U‐Pb Geochronology and Application to Iron Oxide‐Cu‐Au Systems     

Liam Courtney‐Davies  Sarah E. Gilbert  Cristiana L. Ciobanu  Simon R. Tapster  Marcus W. Richardson  Nigel J. Cook  Benjamin P. Wade  Max R. Verdugo‐Ihl  Kathy Ehrig  Daniel J. Condon 《Geostandards and Geoanalytical Research》2021,45(1):143-159

In both nature and synthetic experiments, the common iron oxide haematite (α‐Fe₂O₃) can incorporate significant amounts of U into its crystal structure and retain radiogenic Pb over geological time. Haematite is a ubiquitous component of many ore deposit types and, therefore, represents a valuable hydrothermal mineral geochronometer, allowing direct constraints to be placed on the timing of ore formation and upgrading. However, to date, no suitable natural haematite reference material has been identified. Here, a synthetic haematite U‐Pb reference material (MR‐HFO) is characterised using LA‐ICP‐MS and ID‐TIMS. Centimetre‐scale ‘chips’ of synthesised α‐Fe₂O₃ were randomly microsampled via laser ablation‐extraction and analysed using ID‐TIMS. Reproducible U/Pb and Pb/Pb measurements were obtained across four separate chips (n = 13). Subsequently, an evaluation of the suitability MR‐HFO in constraining U‐Pb data via LA‐ICP‐MS is presented using a selection of natural samples ranging from Cenozoic to Proterozoic in age. The MR‐HFO normalised U‐Pb ratios are more concordant and ages more accurate versus the same LA‐ICP‐MS spot analyses normalised to zircon reference material, when compared with independently acquired ID‐TIMS data from the same natural haematite grains. Results establish MR‐HFO as a suitable reference material for LA‐ICP‐MS haematite U‐Pb geochronology.  相似文献   

Environmental attitudes and adventure tourism motivations     

Julia Kathryn Giddy  Nigel Leigh Webb 《GeoJournal》2018,83(2):275-287

The natural environment plays an important role in adventure tourism. Specific environments are often necessary for certain types of adventure tourism and unique settings are seen to enhance the value of adventure tourism experiences. Given the importance of the environment in adventure tourism, the interplay between humans and the environment in this context should be given further attention. Although much research has examined the physical environmental impacts caused by specific activities considered adventure tourism, the impact of the environment on the behavior of adventure tourists has only briefly been touched upon. Environmental attitudes are said to be an indicator of environmentally conscious behavior. In the tourism context, however, conflicting results have been found as to whether or not environmental attitudes drive consumer behavior. Therefore, the manner in which environmental attitudes, using the New Environmental Paradigm scale, influence the motivations of participants in adventure tourism is investigated using the case of commercial adventure tourism in South Africa. The results show that the environmental attitudes of this group of tourists were relatively low and that the links between environmental attitudes and adventure tourism motivations are relatively weak. Therefore, the impact of general environmental attitudes on adventure tourist behavior is questionable.  相似文献   

Rare earth element geochemistry of feldspars: examples from Fe-oxide Cu-Au systems in the Olympic Cu-Au Province,South Australia     

Kontonikas-Charos  Alkis  Ciobanu  Cristiana L.  Cook  Nigel J.  Ehrig  Kathy  Krneta  Sasha  Kamenetsky  Vadim S. 《Mineralogy and Petrology》2018,112(2):145-172

Mineralogy and Petrology - Rare earth element (REE) fractionation trends in feldspars are reported from Olympic Dam (including Wirrda Well and Phillip’s Ridge) and Cape Donington (Port...  相似文献   

Geological controls on the geometry of incised‐valley fills: Insights from a global dataset of late‐Quaternary examples     

Ru Wang  Luca Colombera  Nigel P. Mountney 《Sedimentology》2019,66(6):2134-2168

Incised valleys that develop due to relative sea‐level change are common features of continental shelves and coastal plains. Assessment of the factors that control the geometry of incised‐valley fills has hitherto largely relied on conceptual, experimental or numerical models, else has been grounded on case studies of individual depositional systems. Here, a database‐driven statistical analysis of 151 late‐Quaternary incised‐valley fills has been performed, the aim being to investigate the geological controls on their geometry. Results of this analysis have been interpreted with consideration of the role of different processes in determining the geometry of incised‐valley fills through their effect on the degree and rate of river incision, and on river size and mobility. The studied incised‐valley fills developed along active margins are thicker and wider, on average, than those along passive margins, suggesting that tectonic setting exerts a control on the geometry of incised‐valley fills, probably through effects on relative sea‐level change and river behaviour, and in relation to distinct characteristics of basin physiography, water discharge and modes of sediment delivery. Valley‐fill geometry is positively correlated with the associated drainage‐basin size, confirming the dominant role of water discharge. Climate is also inferred to exert a potential control on valley‐fill dimensions, possibly through modulations of temperature, peak precipitation, vegetation and permafrost, which would in turn affect water discharge, rates of sediment supply and valley‐margin stability. Shelves with slope breaks that are currently deeper than 120 m contain incised‐valley fills that are thicker and wider, on average, than those hosted on shelves with breaks shallower than 120 m. No correlation exists between valley‐fill thickness and present‐day coastal‐prism convexity, which is measured as the difference in gradient between lower coastal plains and inner shelves. These findings challenge some concepts embedded in sequence stratigraphic thinking, and have significant implications for analysis and improved understanding of ‘source to sink’ sediment route‐ways, and for attempting predictions of the occurrence and characteristics of hydrocarbon reservoirs.  相似文献   

Intermobility of barium,strontium, and lead in chloride and sulfate leach solutions     

Rollog  Mark  Cook  Nigel J.  Guagliardo  Paul  Ehrig  Kathy  Gilbert  Sarah E.  Kilburn  Matt 《Geochemical transactions》2019,20(1):1-12

Iron(III)-precipitates formed by the oxidation of dissolved Fe(II) are important sorbents for major and trace elements in aquatic and terrestrial systems. Their reductive dissolution in turn may result in the release of associated elements. We examined the reductive dissolution kinetics of an environmentally relevant set of Fe(II)-derived arsenate-containing Fe(III)-precipitates whose structure as function of phosphate (P) and silicate (Si) content varied between poorly-crystalline lepidocrocite, amorphous Fe(III)-phosphate, and Si-containing ferrihydrite. The experiments were performed with 0.2–0.5 mM precipitate-Fe(III) using 10 mM Na-ascorbate as reductant, 5 mM bipyridine as Fe(II)-complexing ligand, and 10 mM MOPS/5 mM NaOH as pH 7.0 buffer. Times required for the dissolution of half of the precipitate (t_50%) ranged from 1.5 to 39 h; spanning a factor 25 range. At loadings up to ~ 0.2 P/Fe (molar ratio), phosphate decreased the t_50% of Si-free precipitates, probably by reducing the crystallinity of lepidocrocite. The reductive dissolution of Fe(III)-phosphates formed at higher P/Fe ratios was again slower, possibly due to P-inhibited ascorbate binding to precipitate-Fe(III). The slowest reductive dissolution was observed for P-free Si-ferrihydrite with ~ 0.1 Si/Fe, suggesting that silicate binding and polymerization may reduce surface accessibility. The inhibiting effect of Si was reduced by phosphate. Dried-resuspended precipitates dissolved 1.0 to 1.8-times more slowly than precipitates that were kept wet after synthesis, most probably because drying enhanced nanoparticle aggregation. Variations in the reductive dissolution kinetics of Fe(II) oxidation products as reported from this study should be taken into account when addressing the impact of such precipitates on the environmental cycling of co-transformed nutrients and contaminants.

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Improved Constraints on Models of Glacial Isostatic Adjustment: A Review of the Contribution of Ground-Based Geodetic Observations     

Matt A. King  Zuheir Altamimi  Johannes Boehm  Machiel Bos  Rolf Dach  Pedro Elosegui  François Fund  Manuel Hernández-Pajares  David Lavallee  Paulo Jorge Mendes Cerveira  Nigel Penna  Riccardo E. M. Riva  Peter Steigenberger  Tonie van Dam  Luca Vittuari  Simon Williams  Pascal Willis 《Surveys in Geophysics》2010,31(5):465-507

The provision of accurate models of Glacial Isostatic Adjustment (GIA) is presently a priority need in climate studies, largely due to the potential of the Gravity Recovery and Climate Experiment (GRACE) data to be used to determine accurate and continent-wide assessments of ice mass change and hydrology. However, modelled GIA is uncertain due to insufficient constraints on our knowledge of past glacial changes and to large simplifications in the underlying Earth models. Consequently, we show differences between models that exceed several mm/year in terms of surface displacement for the two major ice sheets: Greenland and Antarctica. Geodetic measurements of surface displacement offer the potential for new constraints to be made on GIA models, especially when they are used to improve structural features of the Earth’s interior as to allow for a more realistic reconstruction of the glaciation history. We present the distribution of presently available campaign and continuous geodetic measurements in Greenland and Antarctica and summarise surface velocities published to date, showing substantial disagreement between techniques and GIA models alike. We review the current state-of-the-art in ground-based geodesy (GPS, VLBI, DORIS, SLR) in determining accurate and precise surface velocities. In particular, we focus on known areas of need in GPS observation level models and the terrestrial reference frame in order to advance geodetic observation precision/accuracy toward 0.1 mm/year and therefore further constrain models of GIA and subsequent present-day ice mass change estimates.  相似文献   

The Significance of the Palghat-Cauvery Shear Zone in Southern India for Correlations between South-West India and Eastern Madagascar     

Nigel Harris 《Gondwana Research》1999,2(3):471

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