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Mechanical stratigraphy encompasses the mechanical properties, thicknesses, and interface properties of rock units. Although mechanical stratigraphy often relates directly to lithostratigraphy, lithologic description alone does not adequately describe mechanical behavior. Analyses of normal faults with displacements of millimeters to 10's of kilometers in mechanically layered rocks reveal that mechanical stratigraphy influences nucleation, failure mode, fault geometry, displacement gradient, displacement distribution, fault core and damage zone characteristics, and fault zone deformation processes. The relationship between normal faulting and mechanical stratigraphy can be used either to predict structural style using knowledge of mechanical stratigraphy, or conversely to interpret mechanical stratigraphy based on characterization of the structural style. This review paper explores a range of mechanical stratigraphic controls on normal faulting illustrated by natural and modeled examples. [ABSTRACT FROM AUTHOR]

In this paper, we analyze small scale examples of thrust faults and related folding in outcrops of the Cretaceous Boquillas Formation within Big Bend National Park in west Texas to develop detailed understanding of the fault nucleation and propagation that may aid in the interpretation of larger thrust system structure. Thrust faults in the outcrop have maximum displacements ranging from 0.5 cm to 9 cm within competent limestone beds, and these displacements diminish both upward into anticlines and downward into synclines within the interbedded and weaker mudrock layers. We interpret the faults as having nucleated within the competent units and partially propagated into the less competent units without developing floor or roof thrusts. Faults that continued to propagate resulted in hanging wall anticlines above upwardly propagating fault tips, and footwall synclines beneath downwardly propagating fault tips. The observed structural style may provide insights in the nucleation of faults at the formation scale and the structural development at the mountain-range scale. Décollement or detachment layers may be a consequence rather than cause of thrust ramps through competent units and could be over interpreted from seismic data. [ABSTRACT FROM AUTHOR]

We suggest that faults in high slip tendency orientations tend to develop larger displacements than other faults. Consequently, faults that accumulate larger displacements are more likely to be reliable indicators of the longer term stress field and should be weighted accordingly in paleostress estimation. Application of a stress inversion technique that uses slip tendency analyses and fault displacements to interpret populations of coherent normal faults within the Balcones Fault System of south-central Texas provides stress estimates that are consistent with established regional stress analyses. Although the method does not require measurement of slip directions, these data, where available, and sensitivity analyses of the angular mismatch between measured slip directions and those predicted by inverted stress states provide high confidence in the stress estimates generated using slip tendency analyses. Close inspection of the fault orientation and displacement data further indicates that subpopulations of faults with orientations different from the regional pattern have formed in response to stress perturbations generated by displacement gradients on an adjacent seismic scale fault. [ABSTRACT FROM AUTHOR]

Abstract: “Fault drag” (deflection of beds or other markers into folds that are convex in the direction of relative slip) is often interpreted as the product of frictional sliding along a fault and progressive tilting of beds with increased amount of displacement along a fault. We analyze two sets of normal faults, with throws ranging from 0.5m to 5m, and associated fault-related folds in mechanically layered upper Cretaceous carbonate, anhydrite, and shale in central Texas. For each fault set, we interpret the fault displacement and fault-related folds exposed in outcrop to represent different stages in the developmental sequence. In both fault sets, faults in dolostone or limestone lose displacement and tip into less competent anhydrite or shale where deformation is accommodated by folding and smaller scale deformation. Fold wavelength is established early and at small displacement (<1m throw). With increasing displacement the monoclinal fold limb steepens and is extended parallel to bedding, locally producing boudinage in the most competent bed between incompetent beds. Clay smear is well developed where a 0.35m thick clay shale is locally thinned to 0.1m associated with fault throws of 0.5 to 5m. Bed tilting and the development of apparent drag is not the product of frictional sliding but instead folding at the tip of an arrested, in this case upwardly, propagating normal fault. We conclude that synthetic dip associated with steep normal faults (i.e., fault drag) should not be assumed to be the product of frictional drag, but must be considered in the context of the mechanical stratigraphy. Instead, fault-tip folding in mechanically layered rocks produces synthetic dip (drag) early in the fault development history prior to propagation of the fault tip through the folded layer. [Copyright &y& Elsevier]

Abstract: The in situ stress state is an important controlling factor for the slip behavior of faults and fractures in the earth''s crust and hence for the productivity of faulted and fractured hydrocarbon reservoirs. Current methods for stress tensor estimation rely on slip vector field data; however, this information is not generally available from data sets that are commonly used in the oil and gas industry. This work presents a new stress inversion approach where slip tendency is used as a proxy for fault displacement, which can easily be extracted from data sets routinely used by the oil and gas industry. The inversion approach is demonstrated using a data set obtained from the Canyon Lake Gorge in Comal County, Texas. [Copyright &y& Elsevier]

Abstract: In normal faulting regimes, the magnitudes and orientations of the maximum and minimum principal compressive stresses may be known with some confidence. However, the magnitude of the intermediate principal compressive stress is generally much more difficult to constrain and is often not considered to be an important factor. In this paper, we show that the slip characteristics of faults and fractures with complex or nonoptimal geometry are highly sensitive to variation or uncertainty in the ambient effective intermediate principal stress (σ′2). Optimally oriented faults and fractures may be less sensitive to such variations or uncertainties. Slip tendency (T s) analysis provides a basis for quantifying the effects of uncertainty in the magnitudes and orientations of all principal stresses and in any stress regime, thereby focusing efforts on the most important components of the system. We also show, for a normal faulting stress regime, that the proportion of potential surfaces experiencing high slip tendency (e.g., T s ≥0.6) decreases from a maximum of about 38% where σ′2 = σ′3, to a minimum of approximately 14% where σ′2 is halfway between σ′3 and σ′1, and increases to another high of approximately 29% where σ′2 = σ′1. This analysis illustrates the influence of the magnitude of σ′2 on rock mass strength, an observation previously documented by experimental rock deformation studies. Because of the link between fault and fracture slip characteristics and transmissivity in critically stressed rock, this analysis can provide new insights into stress-controlled fault transmissivity. [Copyright &y& Elsevier]

Abstract: Groundwater models are critical decision support tools for water resources management and environmental remediation. However, limitations in site characterization data and conceptual models can adversely affect the reliability of groundwater models. Therefore, there is a strong need for continuous model uncertainty reduction. Ensemble filters have recently emerged as promising high-dimensional data assimilation techniques. Two general categories of ensemble filters exist in the literature: perturbation-based and deterministic. Deterministic ensemble filters have been extensively studied for their better performance and robustness in assimilating oceanographic and atmospheric data. In hydrogeology, while a number of previous studies demonstrated the usefulness of the perturbation-based ensemble Kalman filter (EnKF) for joint parameter and state estimation, there have been few systematic studies investigating the performance of deterministic ensemble filters. This paper presents a comparative study of four commonly used deterministic ensemble filters for sequentially estimating the hydraulic conductivity parameter in low- and moderately high-dimensional groundwater models. The performance of the filters is assessed on the basis of twin experiments in which the true hydraulic conductivity field is assumed known. The test results indicate that the deterministic ensemble Kalman filter (DEnKF) is the most robust filter and achieves the best performance at relatively small ensemble sizes. Deterministic ensemble filters often make use of covariance inflation and localization to stabilize filter performance. Sensitivity studies demonstrate the effects of covariance inflation, localization, observation density, and conditioning on filter performance. [Copyright &y& Elsevier]

Since 2009 the Delaware Basin of Texas and New Mexico has experienced increased seismicity related to oilfield operations. Available, near present-day principal stress orientations, relative magnitudes, and vertical stress estimates are integrated to characterize 20 stress domains in the Delaware Basin. Data density, variability, and quality inform classification of most-likely, less likely, and least likely stress tensor fields. A new interpretation of Delaware Basin, 3D basement-rooted faults is analyzed for stability using most-likely stress tensors. Fault stability is expressed in terms of slip tendency (T s) and critical pore pressure (ΔP fc). Individual faults are compared in terms of their stability and potential seismic capability, and stress scenarios can be compared for their effects on fault stability. Faults range from stable to critical under the conditions investigated, 8% of total mapped fault area may become critically stressed by small pore-pressure increases (1 MPa, 145 psi) above ambient. Comparison of stability measures with focal mechanisms of recent pore-pressure-induced seismicity indicates that T s and ΔP fc have predictive value. This work provides critical information for earthquake hazard and mitigation studies in the Delaware Basin. • Comprehensive stress model of a highly productive hydrocarbon province. • Application of stress model to a detailed basin-scale 3-D fault structure model. • Regional fault stability measures compared with recent seismicity. • New representations of fault stability and potential for induced seismicity. • Comprehensive data repository for public use. [ABSTRACT FROM AUTHOR]

Abstract: There are few processes more central to the social and cultural transformation of the inner city in the past half century than gentrification. The social and economic changes that have engendered gentrification have transformed its character and meaning; it has become principally a strategy for redevelopment of brown field sites by the state and capital interests. Based on research in the formerly derelict harbour-front Sydney suburbs of Pyrmont and Ultimo, this paper shows how economic restructuring, state intervention, developers and cultural change have combined to totally transform the area. Drawing on [Wyly, E K and Hammel, D J (2001) Gentrification, Housing Policy, and the new context of Urban redevelopment, in Critical perspectives on Urban Redevelopment, 6 pp. 211–276], we have termed this second wave gentrification. [Copyright &y& Elsevier]

Yucca Mountain, Nevada, is the sole candidate site for underground disposal of high-level radioactive waste in the United States. The mountain is composed of Tertiary (12.8–11.6 Ma) volcanic tuff, cut by west-dipping normal faults that divide the mountain into north-trending, east-dipping cuestas. Geologic characterization of Yucca Mountain by the U.S. Department of Energy (DOE) has focused on mapping lithostratigraphic units, faults (including single plane, small-displacement surfaces of discontinuity, and large-displacement fault zones), and fractures (quasi-planar zones that have experienced loss of cohesion, including joints, partially mineralized joints, veins, and small-displacement faults). Faults and fractures are important to repository design because they affect seismic hazard, rockfall, and fluid transmissivity in the surrounding rock mass. Geologic maps and detailed studies of rock pavements and tunnel walls reveal that faults and fractures within Yucca Mountain are not uniform in orientation or intensity. We investigate two aspects of distributed deformation arising from fault displacement patterns at Yucca Mountain. First, fault-parallel strains (elongation parallel to cutoff lines where stratigraphic horizons intersect fault planes) develop as a result of lateral fault displacement gradients. Using existing data, we analyze the likely state of strain in fault blocks at Yucca Mountain. Second, fault-strike-perpendicular strains can develop where two normal faults propagate past each other. A component of the total strain is distributed into the surrounding rock to produce synthetic layer dip or a network of smaller faults and fractures. We find that small-scale faulting and fracturing at Yucca Mountain is variable and is strongly controlled by larger scale fault system architecture. [Copyright &y& Elsevier]

Twinning of the e-plane is the dominant crystal–plastic deformation mechanism in calcite deformed below about 400 °C. Calcite in a twin domain has a different crystallographic orientation from the host calcite grain. So-called thin twins appear as thin black lines when viewed parallel to the twin plane at 200–320× magnification under a petrographic microscope. Thick twins viewed in the same way have a microscopically visible width of twinned material between black lines. Calcite e-twin width and morphology has been correlated with temperature of deformation in naturally deformed coarse-grained calcite. In this paper, we present a compilation and analysis of data from limestones of the frontal Alps (France and Switzerland) and the Appalachian Valley and Ridge and Plateau provinces (eastern United States) to document this temperature dependence. Mean calcite twin width correlates directly with temperature of deformation such that thin twins dominate below 170 °C and thick twins dominate above 200 °C. Above 250 °C dynamic recrystallization is an important deformation mechanism in calcite. Mean twin intensity (twin planes/mm) correlates negatively with temperature, and a cross plot of twin intensity with twin width can yield information about both strain and temperature of deformation. These relationships provide a deformation geothermometer for rocks that might otherwise yield little or no paleotemperature data. [Copyright &y& Elsevier]

At low differential effective stress and with minimum principal effective stress near zero or tensile, rocks fail in several modes and with variable failure angles. Under these conditions mechanical stratigraphy exerts a significant influence on initial dip of normal faults. Less competent layers fail in shear mode along fractures that approximate the failure angle predicted by a standard rock mechanics analysis. Deformation of more competent layers, which is driven in part by interaction with the more rapidly deforming incompetent layers, produces hybrid mode failure in which failure angles are smaller than in shear mode. Analyses of small-displacement (<1 m displacement) normal faults cutting Cretaceous carbonate strata in west Texas (USA) indicate that fault geometries resulting from this effect commonly display steep segments where the fault traverses more competent beds. Displacement on these faults has caused dilation of steeper segments. Analogous steep dilational fault segments host ore deposits in the North Pennine Orefield, England. Dilatant segments along faults within carbonates of the Cretaceous age Edwards Group near San Antonio, Texas (USA) have been enlarged by groundwater flow, and are important permeability and shallow groundwater infiltration pathways. [Copyright &y& Elsevier]

Fine-grained low permeability sedimentary rocks, such as shale and mudrock, have drawn attention as unconventional hydrocarbon reservoirs. Fracturing – both natural and induced – is extremely important for increasing permeability in otherwise low-permeability rock. We analyze natural extension fracture networks within a complete measured outcrop section of the Ernst Member of the Boquillas Formation in Big Bend National Park, west Texas. Results of bed-center, dip-parallel scanline surveys demonstrate nearly identical fracture strikes and slight variation in dip between mudrock, chalk, and limestone beds. Fracture spacing tends to increase proportional to bed thickness in limestone and chalk beds; however, dramatic differences in fracture spacing are observed in mudrock. A direct relationship is observed between fracture spacing/thickness ratio and rock competence. Vertical fracture penetrations measured from the middle of chalk and limestone beds generally extend to and often beyond bed boundaries into the vertically adjacent mudrock beds. In contrast, fractures in the mudrock beds rarely penetrate beyond the bed boundaries into the adjacent carbonate beds. Consequently, natural bed-perpendicular fracture connectivity through the mechanically layered sequence generally is poor. Fracture connectivity strongly influences permeability architecture, and fracture prediction should consider thin bed-scale control on fracture heights and the strong lithologic control on fracture spacing. [ABSTRACT FROM AUTHOR]

Interpretation of newly acquired modern broadband seismic reflection data and structural restoration of three regional, WNW-ESE oriented cross-sections across the Orphan Basin, Flemish Pass and Flemish Cap provide new insights into rift evolution and structural style in the area. Our results show that regional extension in the Orphan Basin and Flemish Pass area largely occurred between 170 Ma and 135 Ma, and later extension (135 Ma onwards) in the study area was accommodated east of Flemish Cap. Seismic stratigraphic mapping provides evidence for significant thicknesses of Jurassic strata throughout the Orphan Basin and Flemish Pass area, and structural interpretations highlight the importance of crustal-scale extensional detachment faults in controlling the geometry and position of Jurassic sub-basins at a range of scales. Stacked detachment surfaces and coincident extreme crustal attenuation (to ca. 3.1 km) are observed in eastern parts of the Orphan Basin in an area defined in this study as the Orphan Trough. Rifting style in the central, northern, and eastern parts of the Orphan Basin is dominated by low-angle detachment faulting with maximum extension perpendicular to the incipient rift axis. In contrast, structural geometries in the southwestern part of the basin are suggestive of transtensional deformation, and interplay of normal and strike-slip faulting. Results from map-based interpretation show that strike-slip faults within this transtensional zone are associated with displacement transfer between half-grabens of opposing polarity, rather than regional strike-slip displacement. These structures are interpreted as contemporaneous and kinematically linked to displacement along low-angle detachment surfaces elsewhere and are not attributed to distinct episodes of oblique extension. • Regional structural characterization of the Orphan Basin - Flemish Pass – Flemish Cap region. • Kinematic restoration and crustal area balancing of three laterally compatible, regional cross sections. • A single phase of protracted rifting from ca. 170 Ma to 135 Ma is interpreted in the Orphan Basin and Flemish Pass region. • Hyperextension, crustal-scale detachment surfaces and crustal attenuation associated with rift development. • Transtensional deformation in the southern part of the Orphan Basin compatible with rift-related extension. [ABSTRACT FROM AUTHOR]

Abstract: Understanding stress states and rock mass deformation deep underground is critical to a range of endeavors including oil and gas exploration and production, geothermal reservoir characterization and management, and subsurface disposal of CO2. Geomechanical modeling can predict the onset of failure and the type and abundance of deformation features along with the orientations and magnitudes of stresses. This approach enables development of forward models that incorporate realistic mechanical stratigraphy (e.g., including competence contrasts, bed thicknesses, and bedding planes), include faults and bedding-slip surfaces as frictional sliding interfaces, reproduce the overall geometry of the fold structures of interest, and allow tracking of stress and strain through the deformation history. Use of inelastic constitutive relationships (e.g., elastic–plastic behavior) allows permanent strains to develop in response to the applied loads. This ability to capture permanent deformation is superior to linear elastic models, which are often used for numerical convenience, but are incapable of modeling permanent deformation or predicting permanent deformation processes such as faulting, fracturing, and pore collapse. Finite element modeling results compared with field examples of a natural contractional fault-related fold show that well-designed geomechanical modeling can match overall fold geometries and be applied to stress, fracture, and subseismic fault prediction in geologic structures. Geomechanical modeling of this type allows stress and strain histories to be obtained throughout the model domain. [Copyright &y& Elsevier]

Abstract: The occurrence of hybrid failure – the transition from tensile to shear failure – has been controversial. Production of hybrid failure in laboratory experiments in recent years has strengthened the case for hybrid failure, but field recognition has remained elusive. In this paper, we present data from a small-displacement fault in the Hidden Valley fault zone at Canyon Lake Gorge, Texas, which is refracted through mechanically layered carbonates and exhibits surface characteristics expected for hybrid failure on steep fault segments. We discuss field criteria for identifying hybrid fractures and the deformation conditions under which hybrid failure is to be expected. Documented field examples of hybrid fractures are rare, yet presence of hybrid fractures can be useful indicators of stress conditions at the time of failure. Specifically, hybrid fractures are likely indicators of tensile minimum effective stress and low differential stress at failure. [Copyright &y& Elsevier]

Abstract: Purpose: Implementation of evidence-based techniques, such as explicit computerized protocols, has achieved limited success among clinicians. In this study, we describe the development and validation of an instrument for assessing clinicians’ perceptions about use of explicit computerized protocols. Methods: Qualitative assessment of semi-structured interviews with clinicians gave rise to a cognitive model evaluating the factors that motivate clinicians to use explicit computerized protocols. Using these constructs we developed a 35-item instrument which was administered to 240 clinicians (132 nurses, 53 physicians and 55 respiratory therapists), in three health-care institutions. Results: Factor analysis identified nine factors that accounted for 66% of the total variance cumulatively. Factors identified were: Beliefs regarding Self-Efficacy, Environmental Support, Role Relevance, Work Importance, Beliefs regarding Control, Attitude towards Information Quality, Social Pressure, Culture, and Behavioral Intention. The strongest predictor was Beliefs regarding Self-Efficacy, which accounted for 26% of the total variance of intention to use explicit computerized protocols. Results supported the reliability and construct validity of the instrument. Conclusions: Clinicians’ perceptions play a critical role in determining their intention to use explicit computerized protocols in routine clinical practice. Behavioral theories will help us understand factors predicting clinicians’ intention to use explicit computerized protocols and recognize the implications of these factors in the design and implementation of these protocols. [Copyright &y& Elsevier]

The modern requirement for low weight/high strength aircraft structures is placing an every increasing emphasise on the direct use of optimisation methods in the overall design process. In certain cases, such as that of the Blended Wing-Body (BWB) aircraft, the design cannot be successfully completed without the application of optimisation methods. This type of complex design has inevitably led to the growth in the size of the optimisation problem with large numbers of design variables and constraints being required in a design with strong interactions between the various structural components. Treating the problem in the conventional manner with all components considered simultaneously leads to excessive computer run times. In order to control this growth in problem size a multi-level approach has to be used in order to break down the problem into several sub-problems taking into account the structural coupling effects. Such an approach enables the use of parallel computer processing leading to a significant reduction of the computer run time and decreases the design cycle time. [Copyright &y& Elsevier]

The Orphan Basin and Flemish Pass region on the Newfoundland continental margin is a frontier area in terms of oil and gas exploration and remains poorly understood in terms of structural evolution and rift development. The area has few exploration wells and, until recently, sparse seismic data coverage. Existing gravity inversion and seismic refraction data from the area suggest that stretched continental crust in the Orphan Basin is highly attenuated (locally to < 5 km) but previously published structural restorations have been unable to fully restore the continental crust below the Orphan Basin to pre-deformed thicknesses (30–32 km). Here we perform a structural restoration of a regional, WNW-ESE oriented cross-section to investigate crustal structure, rifting style, and structural evolution of the Orphan Basin and Flemish Pass region. Interpretation is constrained by modern regional depth converted broadband 2D and 3D seismic reflection data, well data, and published gravity inversion results. Present-day crustal thicknesses are used as constraints for crustal area balancing and estimation of crustal thinning across the basin. We find that low-angle extensional detachments are widespread in the area, with offsets on individual structures of up to 42 km. Zones of attenuated continental crust are coincident with the presence of low-angle detachment surfaces displaying isostatic uplift of detachment footwalls. Comparison of total extension derived from crustal area balancing vs. structural restoration suggests approximately 39% of extension across the cross-section is unresolvable in seismic data. We attribute this to (i) ductile deformation prior to brittle faulting, (ii) subseismic-scale faulting, (iii) uncertainties in detachment breakaway positions, and (iv) unresolvable later offset of detachment surfaces. Widespread and relatively evenly distributed extension across the Orphan Basin and Flemish Pass region from Middle-Late Jurassic to Early Cretaceous influences sediment distribution across the region. Calibrated regional seismic mapping of the Orphan Basin suggests that significant thicknesses of Jurassic strata exist throughout the area, including in the northwestern part of the study area, where Kimmeridgian and Tithonian strata reach combined thicknesses of up to 4.9 km. • sSignificantthicknesses of Jurassic strataidentified throughout the Orphan Basin and Flemish Pass. • kinematic restoration and crustal area balancing used to constrain timing and amount of extension across the study area. • Structure dominated by low-angle extensional detachments with offsets on individual structures of up to 42 km. • Attenuated continental crust is coincident with low-angle detachment surfaces and isostatic uplift of detachment footwalls. [ABSTRACT FROM AUTHOR]

Left atrial (LA) volumes are related to success of atrial fibrillation (AF) ablation, but the relation to other functional and structural parameters is less well understood. Our goal was to detect potential functional and structural predictors of arrhythmia recurrence after ablation using cardiac magnetic resonance imaging (CMRi) and to non-invasively assess the relation between LA functional and structural remodeling pre- and post-ablation. A total of 55 patients (38 male, age 67 ± 10 years) underwent CMRi prior to and then within 24-h and 3-months after ablation. LA volumes (LAV) and function (as assessed by ejection fraction and peak longitudinal atrial strain (PLAS)) were measured by feature-tracking CMRi, and LA fibrosis/scarring was quantified using late‑gadolinium enhancement (LGE) imaging. Atrial function was lower acutely in patients with recurrence versus those with non-recurrence: [R vs NR: EF Total 27.8 ± 10.3% vs 38.1 ± 11% p = 0.002; EF Active 10.5 ± 8% vs 19.1 ± 12% p = 0.007; EF Passive 19.4 ± 8 vs 25.8 ± 10 p = 0.021; PLAS 13 ± 5.9% vs 20.2 ± 7% p = 0.004]. With univariate analysis, baseline minimum volume (MinLAV, MinLAVi), several baseline functional parameters (EF Total , EF Passive , EF Active , PLAS), and LA-LGE were predictors of recurrence [all p < 0.05]. Acute function (EF Total , EF Passive , EF Active , PLAS) also predicted recurrence (p < 0.01). Lower pre-ablation EF Total , EF Passive , and PLAS correlated with higher amount of pre-ablation LA-LGE (p < 0.05). In a multivariate model including MinLAV, EF Active and LA-LGE (all at baseline), LA-LGE was the only independent predictor of recurrence (p = 0.0322). Pre-ablation function inversely correlated with LA-LGE and was related to success of AF ablation. Multi-parametric and longitudinal assessment of LA function and structure could be helpful in selection of optimal treatment strategies for AF patients by predicting outcomes. • This longitudinal CMRi study reports left atrial (LA) function and structure pre-ablation, acutely (< 24-h) and at follow-up • Lower LA strain (measured in sinus rhythm) correlated with higher fibrosis • Besides baseline LA function and fibrosis, acute functional impairment also associated with AF recurrence • Acute functional impairment was more severe in patients with high baseline LA fibrosis • Poor functional recovery was detected in patients with poor baseline function regardless of the amount of ablation scar [ABSTRACT FROM AUTHOR]

Small-scale synsedimentary folds in the Eagle Ford Formation in southwest Texas formed during deposition in a shallow epicratonic basin on the North American craton. These folds formed by slumping (i.e., gravity-driven deformation) and are characterized by (i) plastic deformation of limestone beds, (ii) discontinuous bedding and thickness changes of limestone beds, (iii) horizontal compactional fabric at high angle to folded bedding, (iv) low-angle or recumbent axial surfaces, and (v) erosion of slumped intervals and/or onlapping by resumed sedimentation. Exposures of the Eagle Ford near the northwest margin of the Maverick Basin reveal slump folds in 1–2 m thick zones with observed lateral extents of 10's to 100's of meters to >1 km – actual extents are likely much larger. Curvilinear fold hinges changing trend by >90° over short distances, indicating markedly non-cylindrical fold geometries. Bed thickness changes reflect flowage of unlithified sediment during slumping, and subsequent compaction. Previous descriptions of slump folds in the Eagle Ford Formation have focused on examples from the hydrodynamic facies of the basal portion, but slump folds are also present in pelagic facies of the upper Eagle Ford. Slump folding locally represents significant shortening (e.g., 50%) and thickening (e.g., 100%) of slumped intervals, with up-dip absence of the same interval represented by missing section, bed terminations, boudinage, and/or extensional faulting. Repeated slumping can result in significant cumulative updip thinning and downdip thickening along depositional slopes. Our experience working unconventional reservoirs in a variety of North American epicratonic basins indicates that slump folding is common and underrepresented in the literature. Criteria for recognizing slumping in the subsurface include a combination of discontinuous and contorted beds, thickening into fold hinges, compactional fabric postdating folds, and inverted or repeated section. Natural fracture networks may be less regular than in similar but flat-lying beds. Occurrence of slump folded intervals adds complexity and unpredictability to unconventional reservoirs, with implications for reservoir quality, drilling, and optimal stimulation during completion. • Synsedimentary slump folding is under-recognized in epicratonic basins, and influences unconventional reservoirs. • Slump folds in outcrops of the Eagle Ford Formation occur in both hydrodynamic and pelagic facies. • Slump folds are dominated by plastic deformation, even in layers that later became competent and brittle. • Compaction resulted in vertical thinning and locally an axial planar fabric in recumbent folds. • Outcrop fracture networks in slumped intervals are less regular than in similar but flat-lying beds. [ABSTRACT FROM AUTHOR]

Background: Severity of left atrial (LA) fibrosis is a strong predictor of atrial fibrillation (AF) ablation success and has been associated with a history of stroke, hypertension, and heart failure (HF). However, it is unclear whether more severe LA fibrosis independently increases the risk of major adverse cardiovascular and cerebrovascular events (MACCE) among those with AF.Objectives: The goal of this study was to evaluate the occurrence and frequency of MACCE by strata of LA fibrosis severity in patients with AF.Methods: This was a retrospective cohort study of 1,228 patients with AF who underwent late gadolinium enhancement (LGE)-cardiac magnetic resonance imaging to quantify LA fibrosis severity between January 2007 and June 2015. Patients were stratified according to Utah stage of LA LGE criteria, and observed for the occurrence of MACCE, which included a composite of stroke or transient ischemic attack (TIA), myocardial infarction, acute decompensated HF, or cardiovascular death. Disease risk score (DRS) stratification was used to control for between-group differences in baseline characteristics and risk.Results: During follow-up, 62 strokes or TIAs, 42 myocardial infarctions, 156 HF events, and 38 cardiovascular deaths occurred. In DRS stratified analysis, the hazard ratio comparing patients with stage IV versus stage I LA LGE was 1.67 (95% confidence interval: 1.01 to 2.76) for the composite MACCE outcome. The only individual component of the MACCE outcome to remain significantly associated with advanced LGE following DRS stratification was stroke or TIA (hazard ratio: 3.94; 95% confidence interval: 1.72 to 8.98).Conclusions: This retrospective analysis demonstrated that more severe LA LGE is associated with increased MACCE risk, driven primarily by increased risk of stroke or TIA. [ABSTRACT FROM AUTHOR]

A 1.5 km long natural cliff outcrop of nearly horizontal Eagle Ford Formation in south Texas exposes northwest and southeast dipping normal faults with displacements of 0.01–7 m cutting mudrock, chalk, limestone, and volcanic ash. These faults provide analogs for both natural and hydraulically-induced deformation in the productive Eagle Ford Formation – a major unconventional oil and gas reservoir in south Texas, U.S.A. – and other mechanically layered hydrocarbon reservoirs. Fault dips are steep to vertical through chalk and limestone beds, and moderate through mudrock and clay-rich ash, resulting in refracted fault profiles. Steeply dipping fault segments contain rhombohedral calcite veins that cross the fault zone obliquely, parallel to shear segments in mudrock. The vertical dimensions of the calcite veins correspond to the thickness of offset competent beds with which they are contiguous, and the slip parallel dimension is proportional to fault displacement. Failure surface characteristics, including mixed tensile and shear segments, indicate hybrid failure in chalk and limestone, whereas shear failure predominates in mudrock and ash beds – these changes in failure mode contribute to variation in fault dip. Slip on the shear segments caused dilation of the steeper hybrid segments. Tabular sheets of calcite grew by repeated fault slip, dilation, and cementation. Fluid inclusion and stable isotope geochemistry analyses of fault zone cements indicate episodic reactivation at 1.4–4.2 km depths. The results of these analyses document a dramatic bed-scale lithologic control on fault zone architecture that is directly relevant to the development of porosity and permeability anisotropy along faults. [ABSTRACT FROM AUTHOR]

Structures in Cretaceous strata in the Devils River Uplift of west Texas include folds, thrust faults, and bedding-parallel veins indicative of contractional deformation in a thrust faulting stress regime. In this study we analyze a series of small-wavelength (meters to tens of meters) folds in roadcut exposures northwest of Del Rio, Texas. The folds have WNW-ESE dominant trends, gently plunging axes, and are gentle to tight with upright to inclined axial surfaces of variable vergence. These structures are interpreted as detachment folds, with detachments within volcanic ash or mudrock beds. Observed thickening in anticline cores was by ductile flow of volcanic ash or mudrock, small-scale folding, and thrust or reverse faulting. Bed-perpendicular calcite veins are common and in some cases are offset by flexural slip on fold limbs, indicating that folding occurred after brittle failure and extension vein formation in lithified rock. Although rare, bed-parallel calcite veins are also present in the exposure and indicative of a thrust faulting stress regime. Occasional normal and reverse or thrust faults are also present in the exposures. Fluid inclusion analysis of vein cements from extension fractures and faults yielded homogenization temperatures of 71–101 °C, and estimated trapping depths of 2.2–3.5 km prior to and coeval with folding. We interpret these folds as having formed during NNE-SSW directed Laramide shortening (∼80–40 Ma) in a thrust-faulting stress regime with >2 km of overburden, rather than as either penecontemporaneous with deposition or after exhumation by caliche formation, as previously interpreted. • Analyses of small-wavelength folds in Devils River Uplift, west Texas. • Folds are typically detached above volcanic ash or mudrock beds. • Calcite veins offset by flexural-slip on fold limbs – bed-parallel veins rare. • Vein fluid inclusions trapped at 71–101 °C, and depths of 2.2–3.5 km. • Folds record NNE-SSW directed Laramide shortening. [ABSTRACT FROM AUTHOR]

The southern Newfoundland transform margin is a crustal-scale transfer zone that juxtaposes continental crust of the Grand Banks with the oceanic domain of the Fogo Basin, offshore SE Newfoundland. This crustal feature is generally accepted as a left-lateral transfer zone between the much-studied Scotian and Newfoundland margins, but relatively little is known about either its crustal-scale architecture or tectonic evolution. Interpretation of newly available regional seismic data from the Newfoundland Ridge and Fogo Basin, offshore Canada provides evidence for approximately 500 km of left-lateral displacement and associated segmented extension between the Late Triassic (210 Ma) and latest Jurassic (145 Ma) as a result of differential extension rates between the conjugate margins of Nova Scotia–Morocco and Newfoundland (Grand Banks)–Iberia. We show that the southern Newfoundland transform margin represents a 100–150 km wide zone of distributed left-lateral displacement across extended continental crust at the SW edge of the Grand Banks, and that crust beneath the Newfoundland Ridge and Fogo Basin is unlikely to be oceanic in origin. Kinematic restorations of regional cross sections and crustal area balancing provide the basis for map-based reconstructions of the area. Our results, which integrate existing plate reconstructions, crustal thickness data, and established age relationships, help to constrain the early structural evolution of the North Atlantic as the African and North American plates separated during Triassic to Jurassic rifting. • The southern Newfoundland transform margin represents a 100–150 km wide zone of distributed left-lateral displacement. • Differing extension rates between Nova Scotia–Morocco and Newfoundland–Iberia led to continental transform margin. • The Fogo Basin and Newfoundland Ridge are underlain by extended continental crust. • Diapirism of syn-rift Triassic evaporites is documented throughout the study area. • Diapirs formed as a result of primarily vertical salt movement from grabens and half-grabens in extended continental crust. [ABSTRACT FROM AUTHOR]

Field observations and structural analysis of a 50-m-wavelength gentle anticline document bed-parallel fibrous gypsum veins ("beef") and calcite veins associated with contractional folding in the Boquillas Formation, east of Langtry, west Texas. Gypsum beef veins with bed-perpendicular fibers accommodated vertical extension of 13% in the anticline, diminishing to 0% in adjacent synclines. Bed-parallel calcite veins accommodated 0–4% vertical extension across the structure, with no clear correspondence of vein distribution to structural position. Homogenization temperatures from two-phase fluid inclusions in calcite veins indicate trapping depths of 2.0–2.7 km. Source rock analysis from unoxidized organic-rich mudrock at the site shows that the rocks never reached hydrocarbon maturation conditions, therefore vein formation cannot be explained by in situ hydrocarbon expulsion. Bed-parallel veins with vertical or bed-perpendicular fibers document a thrust faulting stress regime during contractional folding near the frontal limit of Laramide deformation. Gypsum vein formation may be related to meteoric water interacting with pyrite or H 2 S to form sulfuric acid, dissolution of carbonate, and deposition of gypsum as an auxiliary mineral. Switching between calcite and gypsum mineralization suggests opening and closing of fault and fracture controlled fluid pathways during deformation. • Gentle anticline in mudrock contains calcite veins and fibrous gypsum beef. • Gypsum beef accommodated 13% vertical extension in anticline, 0% in synclines. • Beef formed during amplification of Laramide detachment fold. • Beef not associated with in situ hydrocarbon expulsion. • Switching between calcite and gypsum mineralization records changing fluid sources. [ABSTRACT FROM AUTHOR]

• Statistical shape modeling enables quantitative analysis of anatomical shapes. • Understanding the consequences of different SSM tools is essential for deployment. • Patient-specific anatomical measurements and lesion screening is automated via SSM. • Benchmarking framework is proposed to assess shape models from SSM tools. • Different levels of consistencies exhibited by SSM tools under analysis. [Display omitted] Statistical shape modeling (SSM) is widely used in biology and medicine as a new generation of morphometric approaches for the quantitative analysis of anatomical shapes. Technological advancements of in vivo imaging have led to the development of open-source computational tools that automate the modeling of anatomical shapes and their population-level variability. However, little work has been done on the evaluation and validation of such tools in clinical applications that rely on morphometric quantifications(e.g., implant design and lesion screening). Here, we systematically assess the outcome of widely used, state-of-the-art SSM tools, namely ShapeWorks, Deformetrica, and SPHARM-PDM. We use both quantitative and qualitative metrics to evaluate shape models from different tools. We propose validation frameworks for anatomical landmark/measurement inference and lesion screening. We also present a lesion screening method to objectively characterize subtle abnormal shape changes with respect to learned population-level statistics of controls. Results demonstrate that SSM tools display different levels of consistencies, where ShapeWorks and Deformetrica models are more consistent compared to models from SPHARM-PDM due to the groupwise approach of estimating surface correspondences. Furthermore, ShapeWorks and Deformetrica shape models are found to capture clinically relevant population-level variability compared to SPHARM-PDM models. [ABSTRACT FROM AUTHOR]

Abstract: Background: The dynamic role of the trunk musculature, with respect to stability, has not been fully explored to date. The purpose of this study was, using a transient and multi-directional perturbation, to: (1) quantify the tonic level of activity in the superficial trunk musculature prior to any perturbation; (2) quantify the phasic activity in those same muscles following application of a transient, horizontally directed load; and (3) quantify the direction-dependent behavior of this phasic response. Methods: Twelve healthy individuals were perturbed during sitting via a chest harness in eight horizontal directions. Surface electromyograms were measured bilaterally from the abdominal (rectus abdominis, internal and external obliques) and back musculature (thoracic and lumbar erector spinae) to determine the tonic muscle activity prior to perturbation, and the phasic response following perturbation. A descriptive model was used to characterize the relationship between the phasic response of the muscles due to perturbation and the pulling direction. Findings: Tonic activity in the trunk musculature in upright sitting is low, but still above resting levels by at about 1–3% of the MVC for the abdominal muscles, and 4–6% for the back muscles. Each trunk muscle also showed a direction-specific, phasic activation in response to perturbation, above these tonic levels of activation. This phasic activation was accurately modeled using a descriptive model for each muscle. Interpretation: The obtained muscle activation level and the identified descriptive model will be applied in the design of a closed-loop controller for functional electrical stimulation. [Copyright &y& Elsevier]

Angiotensin-converting enzyme inhibitors and angiotensin receptor blockers may have anti-inflammatory actions, an effect that could explain some of their beneficial effects on cardiovascular events in clinical trials. Coronary artery bypass grafting (CABG) is associated with a systemic inflammatory response and provides a convenient model to examine the effects of such agents. Genetic polymorphisms may be important in influencing the expression of cytokines, such as interleukin-6 (IL-6). We randomized men awaiting CABG to treatment with enalapril, losartan, or control for 2 months before surgery. Systemic IL-6, IL-8, IL-10, and IL-1 receptor agonists were measured before and after surgery, and genotypes for the −174 G/C and −572 G/C IL-6 gene polymorphisms were determined. Total release of the IL-1 receptor agonist was decreased 29% by enalapril and 31% by losartan (adjusted p = 0.041). IL-6 was decreased 17% by enalapril and 20% by losartan. Subjects possessing the −174 GG genotype produced 20% more IL-6 (adjusted p = 0.029). In these high producers of IL-6, release of IL-6 was decreased 51% by enalapril (adjusted p = 0.001) and 32% by losartan (adjusted p = 0.068). Release of IL-10 was nonsignificantly decreased 26% by enalapril and 21% by losartan, whereas IL-8 was not detected. In conclusion, enalapril and losartan significantly decreased release of the IL-1 receptor agonist after CABG. Enalapril produced a highly significant decrease of 51% in the release of IL-6 in patients identified as high producers of IL-6 by the −174 G/C polymorphism, whereas losartan has a similar but less marked effect. The production of IL-6 in this setting is influenced by the −174 G/C polymorphism. [Copyright &y& Elsevier]

Mesoscale deformation in fold-thrust belts and foreland areas occurs during the interaction of evolving stress regimes and mechanical stratigraphy, leading to a progressive deformation sequence. Tensile, hybrid, shear, compactive shear, and compactive failure may all occur in a thrust faulting stress and deformation regime, often contemporaneously in adjacent layers. Mesostructural studies, however, typically identify structural suites that appear inconsistent with a thrust faulting stress regime, such as vertical opening-mode fractures, normal faults, and strike-slip faults. We present a conceptual model that considers the progressive sequence associated with development and eventual waning of fold-thrust belt activity. The general sequence consists of five stages: (1) burial deformation in a normal faulting stress regime, (2) early horizontal contractional deformation in a strike-slip stress regime, (3) horizontal contractional deformation in a thrust faulting stress regime, (4) late horizontal contractional deformation and initial relaxation in a strike-slip stress regime, and (5) horizontal extensional deformation in a normal faulting stress regime. This sequence can be recognized in horizontal or subhorizontal strata in fold-thrust belts and foreland areas, and in more structurally complex structural positions. This model explains common suites of mesostructures, and can be used to (i) predict mesostructural suites in different structural positions, (ii) explain apparently anomalous, but inherited, structures, and (iii) infer paleostress history. F0B7 New conceptual model for progressive deformation sequence in fold-thrust belts and forelands. F0B7 Sequence explains structural suites that are inconsistent with a thrust faulting stress regime. F0B7 Tensile, hybrid, shear, compactive shear, and compactive failure expected. F0B7 Sequence includes normal-faulting, strike-slip faulting, and thrust-faulting stress regimes. F0B7 Model enables prediction of mesostructural suites in different structural positions. [ABSTRACT FROM AUTHOR]