Fluvial to marine transition in the Ordovician of Ireland–A humid-region fan-delta?     

C. J. Pudsey 《Geological Journal》1984,19(2):143-172

The Mweelrea Group (Llanvirnian) in the South Mayo Inlier, western Ireland, consists mainly of coarse shallow-water sandstones with minor slates, cobble conglomerates, and ignimbrite tuffs. The Glenummera Formation at the base (up to 600 m), dominantly well-cleaved slates with some slump features, was deposited in a slope to deep marine shelf environment. A coarsening upward sequence at its top reflects the interaction of fluvial and marine processes, coarse clastic sediments having prograded from the southeast. The rest of the Mweelrea Group (2100 m in the northwest) is dominated by coarse trough cross-bedded sandstone with little evidence for channelling. Three lenticular marine slates (Glendavock, Uggool, and Glenconnelly Formations), up to 200 m thick, wedge out to the southeast. A humid alluvial fan-fan-delta model can explain many features of the Mweelrea Group. Fans built out to the northwest into a relatively small basin with negligible tides and moderate wave energy. Marginal sediments were reworked by waves, occasional storms, and a burrowing fauna.  相似文献   

Rb-Sr whole-rock isochron studies of the Barnesmore and Fanad plutons,Donegal, Ireland     

P. J. O'Connor  C. B. Long  J. A. Evans 《Geological Journal》1987,22(1):11-23

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How conservative is arsenic in coastal marine environments? A study in Irish coastal waters     

Pinelopi Anninou  Rachel R. Cave 《Estuarine, Coastal and Shelf Science》2009

The conservative potential of arsenic in the relatively pristine waters of Galway Bay, an estuarine system in the west of Ireland, is examined through the inter-seasonal variations in the distribution of its total, hydride and non-hydride fractions. The arsenic concentrations in Galway Bay and local fresh water sources at all seasons were lower than what is considered the natural seawater concentration of 2 μg L⁻¹ (27 nM). The effects of physical mixing, biological uptake and regeneration of arsenic on its distribution are considered. The degree of biological uptake and regeneration of the element are determined by a first order speciation between total arsenic (a small part of which should be of organic origin) and hydride arsenic (mostly of inorganic origin). The structural similarity of arsenic species to phosphate in seawater causes arsenic to be taken up by biota, which then have to detoxify it, so results are presented against phosphate to determine the degree of biological transformation of arsenic at different seasons. An in-house, batch type system of hydride generation coupled to electro-thermal atomic absorption spectrometry is used for the analysis of arsenic; this is preceded by UV-digestion prior to the measurement of total arsenic. Results show only a small association of arsenic with phosphate but a near linear, positive distribution pattern between arsenic and salinity in Galway Bay (R² ∼ 0.6), which is reproducible among seasons, indicating that in this environment the biological uptake of arsenic is likely to be a much slower process than the physical mixing of the water masses.  相似文献   

Variability in growth,development and reproduction of the non-native seaweed Sargassum muticum (Phaeophyceae) on the Irish west coast     

Julia Baer  Dagmar B. Stengel 《Estuarine, Coastal and Shelf Science》2010

This study compared seasonal growth, development and reproduction of the invasive brown macroalga Sargassum muticum in habitats with different wave exposure on the Irish west coast. Three field sites with different degrees of wave exposure were chosen for monthly observations to reflect different habitats that were characteristic of the Irish west coast. Growth and receptacle development differed considerably between sites. Growth and receptacle development was lower at the most sheltered site. Here, S. muticum showed signs of early fragmentation in April/May during the two years of investigation (2007 and 2008), whilst the population at an exposed site developed normally and plants grew to a maximum average length of 163 cm by July, with the onset of fragmentation in August. Sargassum muticum in a tide pool exhibited a similar seasonal growth cycle as plants at the exposed open shore site. Overall growth however was stunted, with plants reaching a maximum length of only 30–40 cm in July. Receptacle development was also inhibited at the sheltered site, with a maximum of only 10% of plants found to be fertile during spring and summer 2008, while plants at the exposed site and the tide pool exhibited 100% plant fertility by August. An extensive occurrence of the native epiphyte Pylaiella littoralis on S. muticum was noticed during field sampling at the sheltered study site which may have contributed to inhibited development of S. muticum observed in this area.  相似文献   

Timing of glacial retreat in the Wicklow Mountains,Ireland, conditioned by glacier size and topography          下载免费PDF全文

Matt D. Tomkins  Jason M. Dortch  Philip D. Hughes  Jonny J. Huck  Toby N. Tonkin  Iestyn D. Barr 《第四纪科学杂志》2018,33(6):611-623

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Deglaciation chronology of the Donegal Ice Centre,north‐west Ireland     

Peter Wilson  Colin K. Ballantyne  Sara Benetti  David Small  Derek Fabel  Chris D. Clark 《第四纪科学杂志》2019,34(1):16-28

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The Hekla 1947 tephra in the north of Ireland: regional distribution,concentration and geochemistry     

Heidi A. Rea  Graeme T. Swindles  Helen M. Roe 《第四纪科学杂志》2012,27(4):425-431

A cryptotephra layer from the eruption of Hekla in 1947 has recently been discovered in Irish peatlands. This tephra layer represents the most recent deposition of volcanic ash in the UK prior to the eruption of Eyjafjallajökull in 2010. Here we examine the concentration and geochemistry of the Hekla 1947 tephra in 14 peat profiles from across Northern Ireland. Electron probe microanalysis of individual tephra shards (n = 91) reveals that the tephra is of dacitic–andesitic geochemistry and is highly similar to the Hekla 1510 tephra, although spheroidal carbonaceous particle profiles can be used for successful discrimination of the two layers. The highest concentrations of Hekla 1947 are found in western sites, probably reflecting the pathway of the ash fall event due to the prevailing wind direction. Comparable tephra concentrations from two cores (1 km apart) from a single bog and from nearby sites may suggest that tephra shard concentrations in peat profiles reflect ash fallout densities across a specific region, rather than site‐specific factors associated with peatlands. This paper firmly establishes Hekla 1947 as a useful chronostratigraphic marker for the twentieth century, although within a restricted zone. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Landscape‐scale controls on the spatial distribution of caesium 137: A study based on an airborne geophysical survey across Northern Ireland     

B. G. Rawlins  C. Scheib  D. Beamish  R. Webster  A. N. Tyler  M. E. Young 《地球表面变化过程与地形》2011,36(2):158-169

The spatial distribution of ¹³⁷Cs across the landscape and the processes controlling its redistribution are of interest because (i) ¹³⁷Cs has been widely used to quantify the movement of soil and sediments and (ii) substantial fallout of ¹³⁷Cs after the Chernobyl accident has led to contamination of foodstuffs in some places. A high‐resolution airborne geophysical radiometric survey of Northern Ireland has provided an opportunity to study the distribution and possible redistribution of ¹³⁷Cs. The ¹³⁷Cs activity (recorded at 1·2 million points) is distributed in a series of bands oriented approximately 160° and 115° clockwise from north. Geostatistical analysis of the data shows a strong, short‐range structure (correlation ranges between 0·6 and 8 km) in ¹³⁷Cs activity across the vast majority of the region; the spatial distribution shows association with a published, coarse‐scale depositional pattern of ¹³⁷Cs from Chernobyl. Two indices of land form derived from a digital elevation model, namely compound topographic index and the length–slope factor of the Revised Universal Soil Loss Equation, account for only 3% of the variance in ¹³⁷Cs activity. In contrast, soil type and land cover in combination (including their interaction) account for 20% of the variance. In areas that received moderate fallout from Chernobyl, soil type alone accounts for a substantial proportion of the spatially correlated ¹³⁷Cs activity. We attribute this to each soil type having a fairly uniform radiocaesium interception potential that differs from those of other soil types and that this potential controls the vertical migration of ¹³⁷Cs. Over the granitic Mourne Mountains there is a strong spatial cross‐correlation between ¹³⁷Cs activity and airborne estimates of soil potassium, suggesting that the latter provides a measure of the soil's radiocaesium interception potential; this is probably dominated by the quantity of the mineral illite. Copyright © 2010 John Wiley & Sons, Ltd. and British Geological Survey  相似文献   

爱尔兰矿业投资环境     

何金祥 《国土资源情报》2014,(8):36-40

爱尔兰是欧洲一个岛国,面积70273平方公里,人口约458万,是欧洲一个重要的铅锌矿生产国和出口国。爱尔兰铅锌矿成矿条件良好,政治稳定,法制总体较为健全,基础设施完善,矿业政策积极、稳定,矿业管理规范,矿业税费合理,与我国关系良好。尽管其矿业法律法规有待进一步完善,相关规定也有待进一步明确和细化,但总体来看,爱尔兰属矿业投资环境较良好的国家。  相似文献   

Agriculturally induced environmental changes in the Burren Karst,Western Ireland     

D. Drew 《Environmental Geology》1996,28(3):137-144

 The Burren plateau of County Clare is a classic example of a plateau karst characterised by patchy, thin soils, a lack of defined surface drainage, and in the instance of the Burren, a rich floristic, archaeological and landscape heritage. Since accession to the European Union and, in particular, as a result of Common Agricultural Policy initiatives, attempts have been made to raise farm incomes and to modernise agriculture in areas such as the Burren. Due to the encouragement of land reclamation and silage production has largely replaced hay farming for winter fodder. These changes pose a threat to groundwater quality by enhancing the leaching of artificial fertilizers or of organic pollutants. The Burren is highly vulnerable to water pollution from silage effluent because of its thin or absent soils and its highly karstified aquifers. A full survey of silage clamps was made in the summers of 1991 and 1992. For each site data were collected to derive the following: mass of silage, effluent produced, hazard rating of site to groundwater, likely discharge of effluent to groundwater and groundwater dilution index. About 60% of clamps were considered to be high risk and 23% medium risk. About 92% of all sites probably allow some effluent to infiltrate groundwater. Received: 1 June 1995 · Accepted: 4 December 1995  相似文献