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Determining the sequencing of different deformation mechanisms and styles is crucial to understanding how the Earth’s crust responds to tectonic stress. The sequence of near surface compressional deformation in peripheral orogenic forelands typically starts with an early stage of bulk homogenous shortening, i.e. layer parallel shortening (LPS) followed by folding and contractional faulting. The temporal and spatial distribution of strain is also very much influenced by the inherited basement structure and pre-collisional basin architecture in such foreland settings, in particular inherited extensional fault systems. Tectonic contraction in such settings tends to promote the positive inversion of basins through LPS, folding and reverse faulting by the exploitation of pre-existing bounding structures and facilitated by the lower bulk density and strength of sedimentary fill sequences when compared to the surrounding basement.This study will combine conventional structural field studies from the Variscides of SW Ireland with the spatial characterisation of finite strain using clast shape analysis and anisotropy of magnetic susceptibility (AMS) studies on deformed sandstones as a means of elucidating the temporal and spatial evolution of deformation in an orogenic foreland that is heavily influenced by pre-existing basement architecture and structures. AMS is increasingly seen to be a particularly sensitive proxy for tectonic strain signals in low to medium strain settings on the periphery of orogens.The Variscan of SW Ireland offers an excellent opportunity to investigate the full foreland strain cycle from early bedding parallel oblate fabrics to more prolate intermediate fabrics and finally cleavage parallel oblate fabrics in an overall setting that incorporates marked basement control of the spatial distribution of finite strain. The adopted multi-technique approach will also allow for insights into the relative timing of deformation events.

Particle shape measurement is an important analysis for a number of research and industrial disciplines. Most of the presently available 2-Dimensional shape analysis methods commonly suffer from at least two shortcomings: (1) particles, which are visually distinct, are not easily distinguished and (2) the parameter value is difficult to relate to physical attributes. This contribution seeks to address these issues by introducing the Curvature (κ) plot which can be used to identify particle corners and measure their sharpness. Using the κ plot, four shape parameters are proposed: number of corners, cumulative angularity, sharpest corner and straight fraction. This methodology is applied to synthetic geometrical shapes and 4000 natural sand particle data. The results demonstrate that the four new shape parameters can be collectively used to quantitatively describe particle shape which correlates closely with visual perceptions of particle boundary.

This paper presents new data for historical vein-hosted copper sulfide deposits in the Late Paleozoic Munster and South Munster basins of SW Ireland. Detailed mapping, 3D modelling, fluid inclusion microthermometry and geochronology from the Allihies area of the Beara Peninsula have led to a new interpretation of the timing and development of ore mineralization. Macro- and microstructural studies reveal that the ore-bearing, mainly east–west-striking quartz veins are directly related to early extensional, basinal normal faults. Molybdenite Re–Os dating of the main-stage Cu lode yields ages from 367.3 ± 5.5 to 366.4 ± 1.9 Ma. This early vein system experienced subsequent late Carboniferous Variscan deformation, including cleavage development, sinistral SW–NE strike-slip faulting, cataclastic deformation and recrystallization. The new timing of Cu mineralization in SW Ireland has major implications for its relationship to the base metal deposits of the Irish Midlands. Supplementary material: A video file showing a 3D model of the major lodes and the underground workings at Mountain Mine, and Excel spreadsheets showing fluid inclusion measurements and sample locations of the Allihies Copper Mining District are available at https://doi.org/10.6084/m9.figshare.c.4875015

The Jurassic and Cretaceous sedimentary infill of the Irish and Celtic Sea Basins is intimately associated with the breakup of the supercontinent Pangea, and the opening of the Atlantic margin. Previous basin studies have constrained tectonism, basin uplift and sediment composition, but sediment provenance and routing have not received detailed consideration. Current hypotheses for basin infill suggest localized sediment sourcing throughout the Jurassic and Cretaceous, despite a dynamic tectonic and palaeoenvironmental history spanning more than 100 million years. We present detrital zircon, white mica and apatite geochronology alongside heavy mineral data from five basins. Findings reveal that basin infill derived predominantly from distal sources with lesser periods of local sourcing. We deduce that tectonically induced marine transgression and regression events had a first-order control on distal v. proximal sedimentary sourcing. Additionally, tectonism which uplifted the Fastnet Basin region during the Middle–Late Jurassic recycled basin sediments into the connected Celtic and Irish Sea Basins. Detrital geochronology and heavy mineral evidence support three distinct provenance switches throughout the Jurassic and Cretaceous in these basins. Overall an integrated multi-proxy provenance approach provides novel insights to tectonic and environmental controls on basin infill as demonstrated in the Irish and Celtic Sea Basins. Supplementary material: Tables S1–S6 are available at https://doi.org/10.6084/m9.figshare.c.5343657

Deep geothermal resources in low- to medium-temperature settings remain poorly understood and untapped in Ireland and much of Europe. Our new project DIG (De-risking Ireland’s Geothermal Potential) integrates multi-disciplinary, multi-scale datasets in order to investigate Ireland’s low-enthalpy geothermal energy potential. Seismic measurements constrain the distributions of seismic velocities and, through them, the composition and temperature within the lithosphere and underlying mantle. Recent deployments of broadband seismic stations and the surface-wave measurements using the new data yield an unprecedentedly dense data sampling of the crust and upper mantle beneath Ireland and neighbouring Britain. These data form a foundation for the region-scale, multi-parameter modelling of the thermal state of the lithosphere.We use the recently assembled dataset of over 11,000 Rayleigh-wave, phase-velocity curves, measured for pairs of stations across Ireland and Britain (Bonadio et al. 2021) and complement it with new interstation measurements of Love-wave phase velocities. The measurements were performed using two methods with complementary period ranges, the teleseismic cross-correlation method and waveform inversion. Spanning a very broad period range (from as short as 4 s to as long as 500 s), the phase velocities provide resolution from the upper-middle crust to the asthenosphere. The joint analysis of Rayleigh and Love measurements constrains the isotropic-average shear-wave velocity, relatable to temperature and composition. The optimal-resolution, phase-velocity maps of Bonadio et al. (2021) for Rayleigh waves and the new maps for Love waves computed in this study provide essential constraints on the thermal structure of the region’s lithosphere. We demonstrate this by inverting the data using an integrated geophysical-petrological thermodynamically self-consistent approach (Fullea et al., 2021). The multi-parameter models produced by the integrated inversions fit the surface-wave and surface-elevation data and reveal the temperatures and geothermal gradients within the crust. Bonadio, R., Lebedev, S., Meier, T., Arroucau, P., Schaeffer, A. J., Licciardi, A., Agius, M. R., Horan, C., Collins, L., O'Reilly, B. M., Readman, P. and the Ireland Array Working Group (2021). Optimal resolution tomography with error tracking: imaging the upper mantle beneath Ireland and Britain. Geophys. J. Int., in revision.Fullea, J., Lebedev, S., Martinec, Z., & Celli, N. L. (2021). WINTERC-G: mapping the upper mantle thermochemical heterogeneity from coupled geophysical-petrological inversion of seismic waveforms, heat flow, surface elevation and gravity satellite data. Geophys. J. Int., revised version under evaluation.

Potential deep (greater > 400 m) geothermal resources, within low to medium temperature settings remain poorly understood and largely untapped in Europe. DIG (De-risking Ireland’s Geothermal Potential) is a new academic project started in 2020, which aims to develop a better understanding of Ireland’s (all-island) low-enthalpy geothermal energy potential through the gathering, modelling and interpretation of geophysical, geological, and geochemical data.The overarching research objectives, are to (i) determine the regional geothermal gradient with uncertainty estimates across Ireland using new and existing geophysical and geochemical-petrophysical data, (ii) investigate the thermochemical crustal structure and secondary fracture porosity in Devonian/Carboniferous siliciclastic and carbonate lithologies using wide-angle seismic, gravity and available geochemical data, and (iii) identify and assess the available low-enthalpy geothermal resources at reservoir scale within the Upper Devonian Munster Basin, i.e. the Mallow warm springs region, using electromagnetic and passive seismic methods, constrained by structural geological mapping results. A new hydrochemistry programme to characterise deep reservoir water composition will add further constraints.In the island-scale strand of the project, we are using Rayleigh and Love surface waves in order to determine the seismic-velocity and thermal structure of the lithosphere, with crustal geometry. Together with the legacy surface heat flow, gravity, and newly available long-period MT data, this will place bounds on the shape of regional geotherms. Radiogenic heat production and thermal conductivity measurements for Irish rocks will be incorporated into an integrated geophysical-petrological model, within a scheme able to provide critical temperature uncertainties. Regional-scale research will exploit legacy wide-angle seismic data across the Laurentian and Avalonian geological terranes. Geochemical and petrophysical databases will guide in-house Bayesian inversion tools, to estimate probabilities on model outcomes.Local-scale research will derive subsurface electrical conductivity and velocity images from electromagnetic and passive seismic surveys from the northern margin of the Munster Basin, where the thermal waters tend to have a distinctive chemical fingerprint and a meteoric origin based on available geochemical and isotopic compositions. This local focus aims to directly image fault conduits and fluid aquifer sources at depth, within a convective/conductive region associated with warm springs. This will determine the scale of the geothermal anomaly and hence will evaluate the potential for local- and industrial-scale space heating in the survey locality.This presentation will give an overview of this new research project and will deliver preliminary multi-parameter crustal models produced by the thermodynamic inversions that fit the surface-wave and surface elevation data. The project is funded by the Sustainable Energy Authority of Ireland under the SEAI Research, Development & Demonstration Funding Programme 2019 (grant number 19/RDD/522) and by the Geological Survey Ireland.

Soft tissue balancing is integral in providing stability following total knee arthroplasty (TKA). Although intraoperative contact load sensors are providing insights into the effects of soft tissue balancing, there is still a lack of understanding of the relationship between the knee's ligamentous tensions and joint surface contact loads. This study reports on the development of a multifunctional testing apparatus that can quantify the effects of ligamentous tension on joint contact loads in a controlled repeatable environment.The functional knee apparatus was constructed to act as an anatomical substitute for the benchtop assessment of intraoperative soft tissue balancing. The system was calibrated through reproduction of results from a cadaveric study that employed intraoperative load sensors. Experimentation was then conducted to quantify the effects of tensile pretension variation on measured contact loads throughout the full range of flexion.A linear relationship between the ligamentous tensions and contact loads was observed, with ligaments contributing to 74-80% of the measured contact loads. Ligamentous tensions could be approximated from measured contact loads to within ± 23 N.The proposed apparatus can prove to be a valuable tool in the continued exploration of currently undocumented effects (e.g. surgical alteration) in soft tissue balancing. In addition to quantifying the relationship between ligamentous tensions and joint contact loads, soft tissue loading conditions where bicondylar contact was lost (i.e. known sign of kinematic instability) were identified. As a corollary, this system may be able to provide insights on soft tissue balancing standards predictive of patient outcomes.

Temperature history is one of the most important factors driving subsidence and the overall tectono-stratigraphic evolution of a sedimentary basin. The McKenzie model has been widely applied for subsidence modelling and stretching factor estimation for sedimentary basins formed in an extensional tectonic environment. Subsidence modelling requires values of physical parameters (e.g., crustal thickness, lithospheric thickness, stretching factor) that may not always be available. With a given subsidence history of a basin estimated using a stratigraphic backstripping method, these parameters can be estimated by quantitatively comparing the known subsidence curve with modelled subsidence curves. In this contribution, a method to compare known and modelled subsidence curves is presented, aiming to constrain valid combinations of the stretching factor, crustal thickness, and lithospheric thickness of a basin. Furthermore, a numerical model is presented that takes into account the effect of sedimentary cover on thermal history and subsidence modelling of a basin. The parameter fitting method presented here is first applied to synthetically generated subsidence curves. Next, a case study using a known subsidence curve from the Campos Basin, offshore Brazil, is considered. The range of stretching factors estimated for the Campos basin from this study is in accordance with previous work, with an additional estimate of corresponding lithospheric thickness. This study provides insight into the dependence of thermal history and subsidence modelling methods on assumptions regarding model input parameters. This methodology also allows for the estimation of valid combinations of physical lithospheric parameters, where the subsidence history is known.

The number of stone aggregate sources that provide a high polished stone value and therefore a high skid resistance on road surfaces is relatively small. The factors that influence polished stone value have traditionally been associated with mineralogical and mechanical properties of specific rock-types. This study examines a group of variable lithologies from a single source, that exhibit similar laboratory measured polished stone value readings. It can be shown that multiple properties, including microstructural fabrics, can influence the potential PSV of an aggregate. 3D areal surface measurements of the aggregate surface, obtained using z-stacked digital images, can be combined with traditional mineralogy and microstructural observations, to track the development of surface microtexture from the source through to in-service trafficked sites. These combined methodologies can provide a detailed picture of how specific rock-types or regional geological settings can influence the polished stone value of aggregates and how different and varied factors can control the maintenance of a textured surface throughout its use.

Shape analysis can provide vital information regarding the origin, transport and deposition history of grains. Particle shape measurement has been an active area of research for sedimentologists since the 20th century. With advancement in the field of computation and image analysis, shape analysis can be done in a faster and much more accurate way compared to manual measurements. The results obtained are reproducible as compared to visual qualitative analysis. However, there is a lack of image analysis software tools aimed at the field of sedimentology where the fine details of a particle boundaries are required. Image based Particle Shape Analysis Toolbox (IPSAT) developed in the Mathematica environment for the quantitative characterisation of sedimentary grains in 2-dimensions is presented here. This image analysis toolbox can be used to analyse consolidated as well as loose sediment samples. A total of 12 parameters are available for shape measurement comprising conventional shape parameters (roundness, angularity, circularity and irregularity), mathematically complex shape parameters (fractal dimension and Fourier descriptors) and common geometrical shape parameters (aspect ratio, convexity, solidity, mod ratio, rectangularity and compactness). Additionally, IPSAT offers to compute 6 particle size measurement parameters. Furthermore, 2-D particle size distribution can be transformed to a 3-D size distribution for thin section analysis. Example analyses have been carried out on a sandstone and a loose sediment sample. The toolbox presented here aims to establish a textural analysis methodology to be used by geologists and sedimentologists in particular. It will allow users to quantitatively characterise a large set of grains with a fast, cheap and robust methodology.

The Upper Devonian Munster Basin of southern Ireland has traditionally been viewed as a post-orogenic molasse deposit that was sourced from the Caledonides of central Ireland and subsequently deformed by the end Carboniferous Variscan orogenic event. The basin fill is composed of super-mature quartz arenite sandstone that clearly represents a second cycle of deposition. The source of this detritus is now recognized as Lower Devonian Dingle Basin red bed sequences to the north. This genetic link is based on the degree of similarity in the detrital mica chemistry in both of these units; micas plot in identical fields and define the same trends. In addition, the two sequences show increased textural and chemical maturity up-sequence and define indistinguishable Ar-40/Ar-39 age ranges for the detrital mica grains. Partial resetting of the Ar ages can be attributed to elevated heat flow in the region caused by Munster Basin extension and subsequent Variscan deformation. The combined evidence from southwest Ireland therefore points to a Caledonian or possibly Taconian primary source area that initially shed detritus into the Lower Devonian Dingle Basin which was subsequently recycled into the Upper Devonian Munster Basin following mid-Devonian Acadian basin inversion. (C) 2014 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.

Shape fabrics of elliptical objects in rocks are usually assumed to develop by passive behavior of inclusions with respect to the surrounding material leading to shape-based strain analysis methods belonging to the Rf/ϕ family. A probability density function is derived for the orientational characteristics of populations of rigid ellipses deforming in a pure shear 2D deformation with both no-slip and slip boundary conditions. Using maximum likelihood a numerical method is developed for estimating finite strain in natural populations deforming for both mechanisms. Application to a natural example indicates the importance of the slip mechanism in explaining clast shape fabrics in deformed sediments.

Geological strain analysis of sedimentary rocks is commonly carried out using clast-based techniques, which rely on assumptions regarding clast shapes and orientations as well as distances between clast centres. To evaluate the accuracy of these methods in low strain regimes we have compared strain analysis estimates to the anisotropy of magnetic susceptibility (AMS) in sandstone samples from the Wyoming salient. The Cordilleran Mountain Belt of North America is one of the world's classic foreland fold and thrust belts. The Sevier Belt represents the thin-skinned front of this orogenic event characterized by thrust faults and folds that shortened and translated sequences of Devonian to Cretaceous strata eastward. Deformation increases westward providing an ideal laboratory and geological setting to explore the potential correlation of anisotropy of magnetic susceptibility (AMS) to clast-based strain analyses. Studies attempting to define the relationship between AMS and finite strain have been in vogue since the link between layer parallel shortening and AMS was first established. This relationship, despite proven strong correlations between the AMS tensors and tectonic directions, is generally complicated by competing sub-fabrics as well as the various magnetic anisotropy properties of the minerals contributing to the AMS fabric. Even with these complications, we conclude that AMS is much more sensitive to incipient tectonic fabrics than clast based methods.

Shear folding, which is also referred to as slip folding, involves shear along planes that are oriented approximately parallel to the axial plane of the fold structure. These planes, which are typically axial-planar cleavage planes, facilitate high-angle reverse slip leading to fold limb rotation and amplification. This study builds on recent advances in our understanding of the role of weak fault zones in facilitating slip on misoriented faults; i.e., faults at a high angle to the maximum principal tectonic stress (sigma(1)). Analysis of folded marine sedimentary rocks from the Variscan of southern Ireland provides unambiguous microstructural evidence for reverse shear on chemically weakened cleavage domains. Significant silica loss in these cleavage domains, and as a consequence marked mechanical weakening, is seen as the primary cause for the reverse slip associated with the shear folding of these sedimentary rocks.

The occurrence of vein-hosted base metal mineralisation on the southern coast of Ireland has not been well resolved with the surrounding geological terrane. The mineralised lode structures of the C...

Samples in this paper have been assigned formations based on the Geological Survey of Ireland shapefile released prior to the commencement of the study. However, the authors were not aware that, since obtaining the samples, an updated shapefile had been released. This update affects three of the four apatite samples assigned to the Lower Devonian Ballymore Formation. The location of samples Mb-1, Mb-4 and Mb-5 now places them well within the undifferentiated, Upper Devonian Slieve Mish Group. As outlined in our paper, the apatite ages were originally produced concurrently with apatite fission track analysis and were later used in our study to provide additional provenance information in support of the detrital zircon geochronological data. In the second paragraph of the discussion section we say the following: "Williams et al. (1999) obtained an age of 411 Ma for the Cooscrawn Tuff Bed in the Ballymore Formation, which is older than 22 of the 70 detrital apatites analysed in this formation". The reassignment of the three samples to the Upper Devonian Slieve Mish Group nullifies the above statement. However, our interpretation that the depositional age of the Ballymore Formation is younger than the 411 Ma age given by Williams et al. (1999) is predominantly based upon the evidence given by the six youngest detrital zircons from the formation which underlies the Ballymore Formation (i.e. the Slea Head Formation). These zircons give a concordia age of 405 ± 4 Ma. This suggests that the Ballymore Formation was more than likely deposited after 409 Ma. We do not believe that the reassignment of the three samples has any major impact on our provenance interpretations. The ∼420 Ma age of the majority of the apatites in samples Mb-1, Mb-4 and Mb-5 actually fits with the range of Palaeozoic detrital zircons in sample AK-17 which was taken from the Slieve Mish Group, thereby supporting minor input of rocks affected by end-Scandian metamorphism.

The computer strain analysis methods SAPE, MRL and DTNNM have permitted the characterization of finite strain in two different regions with contrasting geodynamic scenarios; (1) the Talas Ala Tau (Tien Shan, Kyrgyzs Republic) and (2) the Somiedo Nappe and Narcea Antiform (Cantabrian to West Asturian-Leonese Zone boundary, Variscan Belt, NW of Iberia). The performed analyses have revealed low-strain values and the regional strain trend in both studied areas. This study also investigates the relationship between lithology (grain size and percentage of matrix) and strain estimates the two methodologies used. The results show that these methods are comparable and the absence of significant finite strain lithological control in rocks deformed under low metamorphic and low-strain conditions.

Existing methodologies that use ellipsoidal objects for the analysis of geological strain typically assume that these objects acted passively during deformation. This assumption, when not valid, can lead to significant underestimates of strain in rocks deformed under low-grade conditions in orogenic forelands. This is especially true when clastic sedimentary rocks are utilized to measure strain; the competency contrast between clasts and matrix possibly leading to marked ‘non-passive’ behaviour. The systematic nature of this finite strain underestimation may allow for a correction of strain estimates when this type of behaviour is evident.

The current view regarding the timing of regionally developed penetrative tectonic fabrics in sedimentary rocks is that their development postdates lithification of those rocks. In this case, fabric development is achieved by a number of deformation mechanisms, including grain rigid body rotation, crystal-plastic deformation, and pressure solution. The latter is believed to be the primary mechanism responsible for the domainal structure of cleavage in low-grade metamorphic rocks. In this study we combine field observations with strain studies to characterize considerable (>50%) Acadian crustal shortening in a Devonian clastic sedimentary sequence from southwest Ireland. Despite these high levels of shortening there is a marked absence of the domainal cleavage structure and intraclast deformation that are expected with this level of deformation. Fabrics in these rocks are predominantly a product of rigid body rotation and repacking of extraformational clasts during deformation of a clastic sedimentary sequence before lithification was complete.

A solution for the deformation of viscous layers during a two-dimensional general deformation is derived. Layer deformation is found to consist of components of pure shear, simple shear and pure rotation when considered with respect to the layer orientation. It is shown that for external bulk pure shear the layer deformation is typically vastly different to that outside the layer, ranging from pure to simple to super shear depending on layer orientation and viscosity contrast. Treagus' method for determining viscosity ratio from cleavage refraction is re-evaluated and is found to applicable under bulk pure shear. However, the presence of earlier LPS (layer-parallel shortening) can lead to erroneous viscosity ratio estimates. A new approach is developed, relying on the variation of cleavage orientation with layer orientation that is found to be robust with respect to LPS. The method is applied to examples from the Irish Variscides and the new approach has implications for determining whether or not LPS occurred in this foreland setting.

Finite strain analysis of deformed clastic sedimentary rocks below and above the Acadian unconformity on the Dingle Peninsula, SW Ireland, reveals that this boundary represents a significant bulk strain discontinuity. The Late Emsian Acadian event is primarily responsible for penetrative cleavage development and high strain in rocks below the unconformity and not, as previously held, the later Variscan event, which overprinted the peninsula with a weak and localized disjunctive cleavage. The presence of apparent anticlockwise transecting cleavage and implied dextral closure of the Dingle Basin during the Acadian event is compatible with northward convergence of Armorica with respect to Eastern Avalonia.

Constrained automated seeded region growing (CASRG) is an algorithm for automated grain boundary detection. It uses as input a single digitised microphotograph, such as ones obtained from a polarising microscope with an attached digital camera. In addition to this, it requires the user to click on the clasts within the microphotograph that the user wishes to obtain boundaries for. The algorithm requires no subsequent human input. The algorithm is based on the seeded region growing (SRG) algorithm of Adams and Bischof [Adams, R., Bischof, L., 1994. Seeded region growing. IEEE Transactions on Pattern Analysis Machine Intelligence 16, 641–647]. We have modified this algorithm to be guided by constraints and to adapt to the heterogeneity of colour information in the image. Imposition of these pre-determined additional conditions enables automated grain boundary detection without human intervention. The accuracy of CASRG has been validated through two benchmarking comparisons; one lithology with low tectonic strain and a second with high strain are used. The CASRG measurements are compared with those from hand drawn boundaries, which are used as a gold standard. Comparison is made using (a) a non-overlap statistic, (b) shape features, (c) strain estimates. In each case, the CASRG method compares very favourably with the gold standard.

SAPE (Semi-Automatic Parameter Extraction) is a program for extracting information relevant to strain analysis from input digital images. Input images are manually produced by tracing the outlines of objects of interest. This is a less onerous, more objective and much faster task than manual measurement or digitisation of object data (i.e. aspect ratio R i and orientation ϕ i ). SAPE rapidly extracts the required data by using a simple region-growing algorithm to identify regions of interest. Subsequently, the second moments are calculated for each region enabling the common strain analysis parameters to be readily computed. The performance of SAPE was tested on three samples (microphotographs of deformed sandstone and oolite as well as a meter scale photograph of a deformed conglomerate) using a non-overlap statistic. This statistic is a normalised measure of overlap between two regions and can be used to compare different fits applied to the same region. In each case SAPE out-performed the manual method. SAPE offers significant advantages in terms of speed, objectivity and robustness and should facilitate the collection of large datasets for strain analysis.

The Upper Palaeozoic sedimentary rocks of the Munster and South Munster Basins, southern Ireland, lie within the Rhenohercynian Zone of the European Variscan orogeny. This foreland region accommodated shortening during the Asturian phase of Variscan deformation at the end of the Carboniferous by the development of kilometre-scale and lower order folding, high angle reverse faulting and regional fabric development. At the southwestern extremity of the belt lies the Black Ball/White Ball Heads area of the Beara Peninsula where high-level igneous intrusions locally exhibit a close relationship with both the ductile and late brittle phases of Variscan deformation. 40 Ar/ 39 Ar ultra-violet laser analysis of phlogopite crystals from these intrusions (principally trachytic dykes) has yielded ages that, when combined with structural field relationships, help to constrain the timing of Variscan deformation in southern Ireland. These ages include 314.44±1.00 Ma for a penetratively deformed lamprophric pipe on Black Ball Head, 301.98±1.47–298.08±0.61 Ma for dyke material associated with later stage brittle deformation and a date of 296.88±0.60 Ma for an undeformed post-orogenic dyke on White Ball Head.

A new method for calculating finite sectional strain from distributions of elliptical objects is presented. The only assumptions required are that before deformation (1) long axis orientations are uniformly distributed and (2) the distribution of axial ratios is independent of orientation. Importantly, an estimate of the orientation of the long axis of the strain ellipse is not required before the method can be applied. The method is based on the conceptually simple fact that the mean radial length of a set of uniformly oriented ellipses in the unstrained state equates to that of a circle, so that after strain, the mean radial length evaluates to the strain ellipse. Errors associated with the method are calculated from the bootstrap, and a simulation study verifies both the applicability of the new method for finite strain estimation and the accuracy of errors calculated with the bootstrap. The method is applied to a large set of sandstone quartz clast data from the Irish Variscides, whilst cross-checking of results with those from established methods also validates the approach taken.

The density and composition of single generation fluids in quartz veins from two similar host lithologies located either side of the Irish Variscan front were investigated using fluid inclusion microthermometry and crush leach analysis. The front marks the northern boundary of a distinctive cleavage developed under sub-greenschist facies conditions and coincides with the margin of a fault-controlled inverted half graben, the Late Devonian Munster Basin. Trapped fluids in Variscan veins north of this basin have medium salinities (4–14 wt% NaCl eq.) and densities generally compatible with the expected P—T conditions of deformation in the area. Fluids in veins south of the half graben margin can be grouped into those in (a) syn-compressional veins with moderate salinities (8–16 wt%) and (b) late stage veins associated with post-orogenic extension which have trapped high salinity fluids (22–27 wt%). Fluid densities for both vein types are broadly compatible with estimated P–T conditions of both trapping events. Crush-leach analyses reveal that all the fluids analysed have Br/Cl ratios close to SMOW. Variations in I/Cl ratios and cation chemistry indicate significant water/rock interaction for medium salinity fluids on either side of the front. The marked internal consistency in Br/Cl ratios from northern and southern fluids coupled with the broad ranges of cation to chloride ratios suggests that an early homogenous marine brine was subsequently modified by differing migration histories during the Late Palaeozoic tectono-sedimentary evolution of the area. It is contended that on a megascopic scale, gravity driven fluid flow controlled by megascopic fold geometries was the dominant mechanism of fluid migration associated with the buckling phase of the orogen, while expulsion of supra-hydrostatically pressurised fluids is associated with late stage orogenic extension.

Detailed mesostructural and strain analysis investigations across the Killarney Mallow Fault, i.e. the traditional Variscan “Front” in southwest Ireland, reveal that this structural line separates two distinct tectonic regimes. North of the Killarney Mallow Fault bulk shortening orthogonal to orogenic strike is estimated to be 12%, all of which is accounted for by late stage buckling. Microscopic strain analysis reveals that there is only local development of a tectonic fabric. South of the front, bulk shortening is ≈ 40% due to combined layer parallel shortening (LPS), buckling and faulting. Variscan deformation is presented as being essentially coaxial. The regional finite strain pattern outlined above is thought to be primarily controlled by the combined effect of a buried basement obstacle in eastern Iveragh and increased sedimentary pile thickness at the western end of the orogen.

Illite crystallinity studies on metaclastics from the Variscides of SW Ireland range in value from 0.18 to 0.25°Δ2 θ indicating a metamorphic grade in the upper anchizone-lower epizone ( c. 275–325°C). Chlorite geothermometry yields a similar metamorphic temperature range (280–315°C). Combining these data with known overburden estimates for the area ( c. 5km) implies late Palaeozoic geothermal gradients in excess of 60°Ckm −1 . Fluid inclusion studies on quartz veins in these metaclastics reveal two vein types characterized by fluid densities of 0.7–0.93 g cm −3 (Group 1) and 0.9–1.0gcm −3 (Group 2) respectively. This variation in fluid density is thought to be dominantly controlled by temperature, with Group 1 veins linked to late Palaeozoic extension and high geothermal gradients and Group 2 veins associated with subsequent Variscan deformation and lower temperature conditions.

Combined microstructural and fluid inclusion studies on a multiple quartz vein from the Irish Variscides reveal a kinematic history consisting of three separate, dynamically distinct, extensional opening events. The first of these is characterized by trapped fluid at densities of 0.87–0.98 g cm−3, indicative of pressures approximating the estimated lithostatic load, while fluid densities associated with the following two events (0.76–0.91 g cm−3) clearly indicate sub-lithostatic fluid pressures. The combined evidence suggests that these later two opening events were extensional fractures occurring well below the critical depth for tensional σ3 (least effective principal stress). It is argued here that the preservation of such low density fluids, in an environment that conventionally requires supra-lithostatic fluid pressures for hydraulic failure, is due to (i) the influence of a preexisting material anisotropy in the rock that would result in hybrid extensional failure, (ii) the effect of stress heterogeneities associated with the development of crude boudins in the vein.

Enzyme therapy for lysosomal storage disorders directed at correcting the underlying cause of disease represents the most significant recent advance in patient management. This review focuses on two disease groups: glycosphingolipidoses and mucopolysaccharidoses. Specifically, Gaucher disease and Hurler-Scheie syndrome have been selected as the prototypical disorder for each respective class.Musculoskeletal complications are encountered in several of the lysosomal storage disorders and often represent a major source of extraneurologic morbidity, particularly in the subacute or chronic variants. Enzyme therapy has led to improvements in physical and functional well-being. However, bone involvement remains a recalcitrant feature, especially among patients with established disease before institution of therapy.Early diagnosis and appropriate timely intervention are critical in achieving the best therapeutic results. A better understanding of the fundamental mechanisms of bone pathology may enable the identification of complementary approaches (eg, the use of bisphosphonates for severe osteopenia) for optimized outcomes. Symptomatic care and rigorous physical and occupational therapy remain critical components of a comprehensive management approach.

The direct isotopic dating of deformation in orogenic forelands has always been restricted by the lack of suitable syn-kinematic low-grade mineral phases. The mix of detrital, metamorphic and alteration phases in low-grade sedimentary rocks makes the task of dating deformation of such rocks especially difficult. Dating minerals that formed or cooled during the peak thermal event may not necessarily represent the timing of deformation, as there can be significant temporal lags between these two events. Lowgrade regional studies usually yield ages for cleavage development in a given orogenic event and are consequently limited in constraining the full temporal range of upper crustal deformation, including the late stage brittle deformation that is characteristic of foreland settings. The indirect approach of constraining the timing of regional deformation events by dating igneous intrusions associated with the deformation is limited in orogenic forelands. To date, this has essentially involved dating un-deformed, orogenic collapse related, post-orogenic granites that provide an upper age boundary to a given event. Ideally, the use of high-level crustal intrusions requires that these intrusions span the full temporal range of deformation. This is the case in southern Ireland, where it is possible to indirectly constrain the age of Variscan deformation by dating high-level crustal intrusions that are known to be intimately associated with the complete sequence of Variscan deformation. These intrusions, exposed in the Lower Palaeozoic rocks of the Blackball/Whiteball Heads area of SW Ireland, were emplaced as pipes, dykes and sills in both ductile and brittle deformational regimes. By adopting a multifaceted approach and combining these ages with existing chronostratigraphical constraints and observed field structural relationships, the temporal bracketing of Variscan deformation in southern Ireland is possible (Quinn et al., 2005). Ar/Ar UV laser analyses of phlogopite crystals from these intrusions has yielded ages which, when combined with structural field relationships, help constrain the timing of Variscan deformation in southern Ireland. These ages include 314.4 ± 1.0 Ma for a penetratively deformed lamprophric pipe on Blackball Head, 302.0 ± 1.5 to 298.1 ± 0.6 Ma for dyke material associated with later stage brittle deformation and a date of 296.9 ± 0.6 Ma for an un-deformed post-orogenic dyke on Whiteball Head (Quinn et al., 2005).