Alan Morris

Alan Morris
Southwest Research Institute · Space Science Department

About

104
Publications
11,773
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3,269
Citations
Citations since 2016
28 Research Items
1910 Citations
2016201720182019202020212022050100150200250300
2016201720182019202020212022050100150200250300
2016201720182019202020212022050100150200250300
2016201720182019202020212022050100150200250300
Introduction
Skills and Expertise

Publications

Publications (104)
Article
Full-text available
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 fol...
Article
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 lit...
Article
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,...
Article
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...
Article
Full-text available
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 Flem...
Article
Full-text available
The Orphan Basin and Flemish Pass regions on the Newfoundland continental margin are frontier areas 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 refr...
Article
Full-text available
Failure behaviors can strongly influence deformation-related changes in volume, which are critical in the formation of fault and fracture porosity and conduit development in low-permeability rocks. This paper explores the failure modes and deformation behavior of faults within the mechanically layered Eagle Ford Formation, an ultra-low permeability...
Preprint
Full-text available
Abstract. Failure behaviour can strongly influence deformation-related changes in volume, which is critical in the formation of fault and fracture porosity and conduit development in low permeability rocks. This paper explores the failure modes and deformation behaviour of faults within the mechanically layered Eagle Ford Formation, an ultra-low pe...
Article
Faults have complicated shapes. Non-planarity of faults can be caused by variations in failure modes, which in turn are dictated by mechanical stratigraphy interacting with the ambient stress field, as well as by linkage of fault segments. Different portions of a fault or fault zone may experience volume gain, volume conservation and volume loss si...
Article
Facies of the Boquillas and equivalent Eagle Ford Formation can be assigned to two associations: a hydrodynamically recycled association and a pelagic association. The hydrodynamically recycled association is composed of lenticular to continuous cross-laminated lime packstone–grainstone, heterolithic facies, and intraclastic grainstone conglomerate...
Article
Full-text available
The Youngstown earthquake sequence of 2011 is one of the clearest examples of inadvertently induced seismicity for which detailed documentation is available. In this paper, we investigate (i) likely stress states in the vicinity of the injection well, (ii) a range of likely permeability scenarios, and (iii) relatively simple methods by which induce...
Article
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 Format...
Article
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 se...
Article
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 kilome...
Article
Analyses of normal faults in mechanically layered strata reveal that material properties of rock layers strongly influence fault nucleation points, fault extent (trace length), failure mode (shear v. hybrid), fault geometry (e.g. refraction through mechanical layers), displacement gradient (and potential for fault tip folding), displacement partiti...
Article
Mapping of normal faults cutting the Bishop Tuff in the Volcanic Tableland, northern Owens Valley, California, using side-looking airborne radar data, low-altitude aerial photographs, airborne light detection and ranging (LiDAR) data, and standard field mapping yields insights into fault scarp development, fault system evolution, and timing. Fault...
Article
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 techniqu...
Article
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...
Article
Characterizing natural fracture systems involves understanding fracture types (faults, joints, and veins), patterns (orientations, sets, and spacing within sets), size distributions (penetration across layering, aperture, and trace length), and timing relationships. Traditionally, observation-based relationships to Ethology, mechanical stratigraphy...
Conference Paper
Full-text available
using passive seismic data from surface arrays. Until now the only stress information available from passive seismic methods has been derived from the focal mechanism solutions of microearthquakes (MEQs). This method has several weaknesses: • The P and T axes of the solution do not correspond to the maximum and minimum compressive stress axes even...
Article
Outcrops of the middle Eagle Ford Formation in south-central Texas reveal well-developed joint networks in subhorizontal competent carbonate (chalk) beds and less well developed networks in interlayered incompetent calcareous mudrock beds. Northeast-striking bed-perpendicular joints in competent beds have the longest trace lengths and are abutted b...
Article
Full-text available
The increasing exploration and production in unconventional resource plays in the past decade has been accompanied by a greater need for understanding the effectiveness of multistage hydraulic fracturing programs, particularly in long (> 1500 m or 5000 ft) subhorizontal boreholes (laterals). Traditional (analytical) analysis techniques for estimati...
Article
Production from self-sourced reservoirs relies on natural and induced fracturing for permeability and conductance of hydrocarbons to the producing wellbores, thus natural or induced fracturing is often a key to success in unconventional reservoir plays. On the other hand, fractures may compromise seals and large or well-connected fractures or fault...
Article
Grooved terrain on Ganymede consists of distinct areas of parallel to sub-parallel ridges and troughs at a variety of spatial scales. Grooved terrain has been interpreted as the product of tectonism in the form of fault-accommodated distributed lithospheric extension. We use physical analog methods to test the formation of grooved terrain by imbric...
Article
Faults are important components of hydrocarbon and other reservoirs; they can affect trapping of fluids, flow pathways, compart-mentalization, production rates, and through these, production strategies and economic outcomes. Displacement gradients on faults are associated with off-fault deformation, which can be manifest as faulting, extension frac...
Article
Full-text available
The Tharsis region of Mars is characterized by large volcanic and tectonic centres that have been active throughout Martian geological history, including distinct sets of graben that extend radially for distances of hundreds to thousands of kilometres. Formation of these graben has been attributed to crustal extension and/or dyke propagation. Physi...
Patent
Full-text available
A computer-implemented method of determining the stress state associated with a geological fault is described. The source data comprises measured fault displacement values, or proxy displacement values, associated with the fault. An error function calculates error as a function of normalized fault displacement and normalized slip tendency. Candidat...
Article
Physical analog models show that distinct deformation styles, mainly contractional, are associated with igneous intrusions.
Article
“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 0.5 m to 5 m, and...
Article
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...
Article
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...
Article
Mature and aging clastic-dominated hydrocarbon fields commonly become increasingly difficult to produce, causing lower economic return than initially forecast. A major cause of this reduced economic viability is compartmentalization, defined as limitation on the ability to produce hydrocarbons resulting from permeability barriers within a field. Th...
Article
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 set...
Article
Analog models of dike injection were performed to determine style and magnitude of structural deformation associated with the dike. Primary deformation style is contraction rather than extension, indicating that martian dikes may not create grabens.
Article
Full-text available
We study the effects of planform dome shape on fault patterns developing with and without concurrent regional extension oriented oblique to the long axis of the dome. The motivation was the need to understand fault and fracture patterns in two adjacent mature hydrocarbon fields in the Middle East: one, an elliptical dome, and one, an irregularly sh...
Article
Eastern California and southwestern Nevada represent an area of Tertiary and Quaternary extensional and dextral transtensional deformation. We used zircon and apatite fission-track thermochronology to study the distribution and timing of tectonic exhumation resulting from extensional and transtensional detachment faulting in this area. Sampling eff...
Article
The Hidden Valley fault is exposed in Canyon Lake Gorge (central Texas) and cuts the Cretaceous Glen Rose Formation. This exposure provides an opportunity to explore the relationship between deformation mechanisms and fault displacement along 830 m (2723 ft) of a normal fault typical of those in carbonate reservoirs and aquifers around the world. T...
Article
Normal faults observed in extensional clay models evolve by displacement (throw) accumulation and concomitant trace length increase, and by segment linkage. The first of these processes leads to an increase in the maximum throw to trace length (Dmax/L) ratio, whereas the second leads to a decrease in this ratio. With increasing extension individual...
Article
Physical analog modeling and analyses of martian fault systems support the interpretation that simple faults on Mars do not grow in a self-similar manner and that compound fault systems develop in a stepwise pattern in Dmax/L space.
Article
The stress state is an important controlling factor on the slip behavior of faults and fractures in the earth’s crust and hence on the productivity of faulted and fractured hydrocarbon reservoirs. Uncertain or poorly constrained estimates of stress states can lead to high risk both in drilling and production costs. Current methods for stress tensor...
Article
Grooved terrain on Ganymede consists of parallel to sub-parallel ridges and troughs at a variety of spatial scales. Grooved terrain is observed in imagery as individual lanes and polygonal crosscutting swaths of bright terrain. Grooved terrain has been interpreted as the product of crustal extension expressed as rotational block faulting. Individua...
Article
Field structural data from the Big Brushy Canyon monocline developed in Cretaceous strata of west Texas are combined with nonlinear finite element modeling to help bridge the gap between geometric, kinematic, and mechanical analysis techniques for understanding the deformation history of reservoir-scale geologic structures. The massive Santa Elena...
Article
The ability to predict rock mass deformation deep underground is important to a broad spectrum of endeavors including oil and gas exploration and production, geothermal reservoir characterization and management, and subsurface disposal of CO 2. Geomechanical modeling can predict the onset of failure and the type and abundance of deformation feature...
Article
Normal faults measured in exposures of Cretaceous carbonate rocks in Texas provide the basis for fault-strain determination, analysis of fault displacements, and exploring the function of mechanical stratigraphy in influencing fault-size distributions. Layer competence and competence contrast, measured using a Schmidt hammer, allow the analysis of...
Article
Understanding and interpreting the timing, location, orientation, and intensity of natural fractures within a geologic structure are commonly important to both exploration and production planning activities. Here we explore the application of finite-element-based geomechanical models to fracture prediction. Our approach is based on the idea that na...
Article
Small-scale brittle faults and fractures that cut bedded tuffaceous sediments of variable textures and grain sizes were studied in a 110-m-long cutbank exposure of poorly consolidated sediments at the southern erosional boundary of the Volcanic Tableland, Owens Valley, California. This study was motivated by the need to evaluate potential length sc...
Conference Paper
Prediction, assessment, and mitigation of surface-affecting natural hazard processes such as landslides, avalanches, earthquakes, and floods call upon geoscientists to rapidly deploy instruments and accurately characterize these earth processes, often with little lead time and under dangerous working conditions. Affected areas may have heavy tree c...
Article
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 t...
Article
Faults are among the most numerous deformation features on Earth and are common on other planetary bodies in the solar system. Small faults, in terms of either displacement or trace length, outnumber large faults, and the distribution is well-described by some form of power-law relationship. However, this observation may be of limited practical use...
Article
Displacement versus length relationships of faults on Earth and Mars have been used to describe and interpret the evolution of faults and fault systems, infer differences in the relative strengths of strata, and evaluate variations in fault-system response to differences in gravity from planet to planet. In this presentation, we focus on maximum th...
Article
Normal faults in Cretaceous carbonates in the Balcones fault system provide important analogs for fault zone architecture and deformation in carbonate reservoirs worldwide. Mechanical layering is a fundamental control on carbonate fault zones. Relatively planar faults with low-displacement gradients develop in massive, strong, clay-poor limestones...
Article
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...
Article
Mechanical stratigraphy exerts a first-order control on deformation at a range of scales from oilfield-scale structural style to deformation (e.g. fracturing) within an individual reservoir stratum. This paper explores an outcrop example where mechanical stratigraphy in a limestone and shale sequence directly influenced the structural style and dis...
Article
Physical analog modeling of grooved terrain has produced geometrically similar morphology to the fault systems on Ganymede. Models suggest that the grooved terrain on Ganymede formed by imbricate normal faulting at 25% or greater extension.
Article
Tectonic models of Yucca Mountain (YM), Nevada, site of the USA's proposed high-level nuclear waste repository, are based on understanding the nature of deformation affecting the site. Using mapped fault dips (50° in the north to 70° in the south) from the Bare Mountain fault (BMF, 15 to 25 km [9.3 to 15.5 mi] west of YM) and the surface geology of...
Article
Water is the most important Martian exploration target - key to finding evidence of past life and providing a crucial resource for future exploration. Water is thought to be present in vapor, liquid, and ice phases on Mars. Except for ice in polar regions, little direct evidence of current surface accumulation of water has been found. Existing rese...
Article
Newly developed terrestrial approaches were applied to martian fault networks to quantify the extent and degree of fault network connectivity. These techniques will provide key constraints for martian hydrological models.
Article
Field analyses of normal faulting illustrate that synthetic layer dip associated with normal faults is a common feature of extensional fault systems. These synthetic dip panels are developed where layers on upthrown, downthrown, or both sides of a normal fault dip toward the downthrown side of the fault. Synthetic dip panels adjacent to normal faul...
Article
Sandbox analog modeling experiments provide new insights into the effects of fault geometry on reservoir connectivity. During progressive distributed extension, three phases of fault system evolution are apparent. In Phase I, geometrically simple faults nucleate rapidly at a large number of sites throughout the deforming region. This is followed by...