The 3D facies architecture and petrophysical properties of hyaloclastite delta deposits: An integrated photogrammetry and petrophysical study from southern Iceland     

Lois Greenfield  John M. Millett  John Howell  Dougal A. Jerram  Timothy Watton  David Healy  Malcolm J. Hole  Sverre Planke 《Basin Research》2020,32(5):1081-1104

Hyaloclastites develop where lava interacts with water resulting in deposits that have a unique and often complex range of petrophysical properties. A combination of eruptive style and emplacement environment dictates the size, geometry and distribution of different hyaloclastite facies and their associated primary physical properties such as porosity, permeability and velocity. To date, links between the 3D facies variability within these systems and their petrophysical properties remain poorly understood. Hjörleifshöfði in southern Iceland presents an exceptional outcrop exposure of an emergent hyaloclastite sequence >1 km wide by >200 m high and enables an investigation of the distribution of the hyaloclastite deposits at seismic scale. Within this study we present a photogrammetry-based 3D model from part of this recent hyaloclastite delta and incorporate previous work by Watton et al. (Journal of Volcanology and Geothermal Research, 2013, 250, 19) to undertake detailed facies interpretation and quantification. Laboratory petrophysical analyses were performed on 34 core plugs cut from key field facies samples, including P- and S-wave velocity, density, porosity and permeability at both ambient and confining pressure. Integration of the 3D model with the petrophysical data has enabled the production of pseudo-wireline logs and property distribution maps which demonstrate the variability of physical properties within hyaloclastite sequences at outcrop to seismic scale. Through comparison of our data with examples of older buried hyaloclastite sequences we demonstrate that the wide-ranging properties of young hyaloclastites become highly uniform in older sequences making their identification by remote geophysical methods for similar facies variations more challenging. Our study provides an improved understanding of the petrophysical property distribution within hyaloclastite sequences and forms a valuable step towards improving the understanding of similar subsurface sequences and their implications for imaging and fluid flow.  相似文献   

Modeling of inundation dynamics on Banda Aceh,Indonesia during the great Sumatra tsunamis December 26, 2004     

Gegar Prasetya  Jose Borrero  Willem de Lange  Kerry Black  Terry Healy 《Natural Hazards》2011,58(3):1029-1055

The tsunami inundation flows on Banda Aceh, Indonesia reached 5 km inland during the December 26, 2004, event and devastated most of the houses, buildings, and infrastructure along the coast and killed more than 167,000 people. The overland flows from the northwest coast and the west coast collided at Lampisang village approximately 3.7 km from Ulee Lheue (northwest coast) and 6.8 km from Lhok Nga (west coast) as reported by survivors. Inundation modeling based on the nonlinear shallow-water wave equations reproduces the inundation pattern and demonstrates a colliding of the overland flows. The model suggests that wave characteristics on the northwest coast of Banda Aceh were different from those on the waves that impacted upon the west coast. The areas, which experienced higher inundation levels, did not always experience greatest overland flow speeds, and the damage areas mostly coincide with the flow speed distribution rather than the runup and inundation depth.  相似文献   

Influence of a thin veneer of low‐hydraulic‐conductivity sediment on modelled exchange between river water and groundwater in response to induced infiltration     

Donald O. Rosenberry  Richard W. Healy 《水文研究》2012,26(4):544-557

A thin layer of fine‐grained sediment commonly is deposited at the sediment–water interface of streams and rivers during low‐flow conditions, and may hinder exchange at the sediment–water interface similar to that observed at many riverbank‐filtration (RBF) sites. Results from a numerical groundwater‐flow model indicate that a low‐permeability veneer reduces the contribution of river water to a pumping well in a riparian aquifer to various degrees, depending on simulated hydraulic gradients, hydrogeological properties, and pumping conditions. Seepage of river water is reduced by 5–10% when a 2‐cm thick, low‐permeability veneer is present on the bed surface. Increasing thickness of the low‐permeability layer to 0·1 m has little effect on distribution of seepage or percentage contribution from the river to the pumping well. A three‐orders‐of‐magnitude reduction in hydraulic conductivity of the veneer is required to reduce seepage from the river to the extent typically associated with clogging at RBF sites. This degree of reduction is much larger than field‐measured values that were on the order of a factor of 20–25. Over 90% of seepage occurs within 12 m of the shoreline closest to the pumping well for most simulations. Virtually no seepage occurs through the thalweg near the shoreline opposite the pumping well, although no low‐permeability sediment was simulated for the thalweg. These results are relevant to natural settings that favour formation of a substantial, low‐permeability sediment veneer, as well as central‐pivot irrigation systems, and municipal water supplies where river seepage is induced via pumping wells. Published in 2011 by John Wiley & Sons, Ltd.  相似文献   

Sediment transport near the Tauranga entrance to Tauranga Harbour   总被引：2，自引：2，他引：0  

R. J. Davies‐Colley  T. R. Healy 《新西兰海洋与淡水研究杂志》2013,47(3):237-243

Abstract

Sediment transport at the Tauranga Entrance was studied in relation to tidal currents and waves. Bedforms resulting from tidal flow were investigated with scuba divers and echo‐soundings. The alignment and scale of bedforms indicated the direction and approximate rate of sediment transport. Sediment transport was measured directly using sediment traps, and results were compared with rates calculated by another method. Maximum sediment transport rates of 20 000–30 000 g.m^?1 per half tidal cycle occur near the inlet gorge, but rates vary considerably in time and space, depending mainly upon power of tidal currents. A model of sediment transport for this inlet has been evolved based on tidal flow streamlines, bedform features, and the measured and calculated rates of sediment transport.  相似文献   

Activation of zinc sulphide with CuII,CdII and PbII: II. Activation in neutral and weakly alkaline media     

J. Ralston  T.W. Healy 《International Journal of Mineral Processing》1980,7(3):203-217

The results of a study of the activation of zinc sulphide by the heavy metal ions Cu^II, Cd^II and Pb^II are reported here. Metal-ion uptake follows a logarithmic dependence on time, depending on the particular metal ion and pH region. In some cases there is no well-defined rate equation. A mechanism for the activation process is proposed and related to activation in weakly acidic media.  相似文献   

Late Pleistocene glacial chronology of the Taylor Valley,Antarctica, and the global climate     

C.H. Hendy  T.R. Healy  E.M. Rayner  J. Shaw  A.T. Wilson 《Quaternary Research》1979,11(2):172-184

Carbonate-rich lacustrine and deltaic deposits, containing thin beds of finely laminated carbonates and thick beds of silt, crop out at several sites in the Taylor Valley and have been encountered in cores obtained by the Dry Valley Drilling Project (DVDP). Fragments of the more indurated carbonate beds have widespread occurrence as part of the desert “lag gravel” which covers much of the valley floor. Analysis of the carbonates suggests that they were deposited as algal limestones from waters derived from the East Antarctic Ice Sheet via the Taylor Glacier at times which correspond to the previous three global interglacial periods, as evidenced by the ice volumes deduced from oxygen-isotopic analysis of oceanic cores. The lacustrine carbonates have been found up to 30 km beyond the present terminus of the Taylor Glacier, and up to 100 m above the level of Lake Bonney, into which the Taylor Glacier at present discharges. It is concluded that the Taylor Glacier has advanced during each of the previous three interglaciations, and it is suggested that this has been caused by a thickening of the East Antarctic Ice Sheet during the interglaciations.  相似文献   

Excursions of the Pleistocene geomagnetic field recorded in Gulf of Mexico sediments     

W.K. Freed  N. Healy 《Earth and Planetary Science Letters》1974,24(1):99-104

The detrital remanent magnetism of a series of deep-sea sediment cores from the Gulf of Mexico has been measured. Together with microfaunal analysis, the data show that excursions of the geomagnetic field occurred at 17,000 ± 1500years B.P. and32,000 ± 1500 years B.P. It is suggested that the former may be the Laschamp excursion and that the latter may be the Lake Mungo excursion. No similar geomagnetic behavior is detected for the past 50,000 years. Sedimentation rates as high as 19 cm per 1000 years are indicated.Susceptibility (χ) maxima in the cores are due to tephra layers. Correlation between the intensity of magnetization (J) and χ shows that variations of intensity are more a function of ferrimagnetic mineral concentrations than geomagnetic field intensity variations.  相似文献   

The Main Problem in Satellite Theory Revisited     

Liam M. Healy 《Celestial Mechanics and Dynamical Astronomy》2000,76(2):79-120

Using the elimination of the parallax followed by the Delaunay normalization, we present a procedure for calculating a normal form of the main problem (J ₂ perturbation only) in satellite theory. This procedure is outlined in such a way that an object-oriented automatic symbolic manipulator based on a hierarchy of algebras can perform this computation. The Hamiltonian after the Delaunay normalization is presented to order six explicitly in closed form, that is, in which there is no expansion in the eccentricity. The corresponding generating function and transformation of coordinates, too lengthy to present here to the same order; the generator is given through order four. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Evaluation of Amendments to Control Phosphorus Losses in Runoff from Pig Slurry Applications to Land     

Cornelius J. O' Flynn  Owen Fenton  Mark G. Healy 《洁净——土壤、空气、水》2012,40(2):164-170

If spread in excess of crop requirements, incidental phosphorus (P) losses from agriculture can lead to eutrophication of receiving waters. The use of amendments in targeted areas may help reduce the possibility of surface runoff of nutrients. The aim of this study was to identify amendments which may be effective in reducing incidental dissolved reactive phosphorus (DRP) losses in surface runoff from land applied pig slurry. For this purpose, the DRP losses under simulated conditions across the surface of intact grassland soil cores, loaded with unamended and amended slurry at a rate equivalent to 19 kg P ha^?1, were determined over a 30 h period. The effectiveness of the amendments at reducing DRP in overlying water were (in decreasing order): alum (86%), flue gas desulfurization by‐product (FGD) (74%), poly‐aluminum (Al) chloride (PAC) (73%), ferric chloride (71%), fly ash (58%), and lime (54%). FGD was the most costly of all the treatments (€7.64/m³ for 74% removal). Ranked in terms of feasibility, which takes into account effectiveness, cost, and other potential impediments to use, they were: alum, ferric chloride, PAC, fly ash, lime, and FGD.  相似文献   

Variably saturated groundwater modelling for optimizing managed aquifer recharge using trench infiltration   总被引：1，自引：0，他引：1       下载免费PDF全文

Victor M. Heilweil  Jerome Benoit  Richard W. Healy 《水文研究》2015,29(13):3010-3019

Spreading‐basin methods have resulted in more than 130 million cubic metres of recharge to the unconfined Navajo Sandstone of southern Utah in the past decade, but infiltration rates have slowed in recent years because of reduced hydraulic gradients and (or) clogging. Trench infiltration is a promising alternative technique for increasing recharge and minimizing evaporation. This paper uses a variably saturated flow model to further investigate the relative importance of the following variables on rates of trench infiltration to unconfined aquifers: saturated hydraulic conductivity, trench spacing and dimensions, initial water‐table depth, alternate wet/dry periods, and number of parallel trenches. Modelling results showed (1) increased infiltration with higher hydraulic conductivity, deeper initial water tables, and larger spacing between parallel trenches, (2) deeper or wider trenches do not substantially increase infiltration, (3) alternating wet/dry periods result in less overall infiltration than keeping the trenches continuously full, and (4) larger numbers of parallel trenches within a fixed area increases infiltration but with a diminishing effect as trench spacing becomes tighter. An empirical equation for estimating expected trench infiltration rates as a function of hydraulic conductivity and initial water‐table depth was derived and can be used for evaluating feasibility of trench infiltration in other hydrogeologic settings. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献