Washita Valley Fault Research Articles

A structural analysis of the Washita Valley Fault in the southeast Anadarko Basin

We propose that the Washita Valley Fault in the southeast Anadarko Basin originated when Precambrian-Cambrian preexisting rift-related faults became reactivated as a rotational stress field reached a favorable orientation for strike-slip displacement. During the Early to Middle Pennsylvanian, contractional deformation dominated as a Precambrian-Cambrian failed rift underwent structural inversion along a northeast-directed stress field. Structures that developed in the basin consisted primarily of thin-skinned fold-thrust structures resulting from slip along two main detachment levels. By the Late Pennsylvanian, stress rotated toward the east–northeast causing left-lateral strike-slip displacement along east–west-oriented structures. During this time, the Washita Valley Fault originated from an east–west-oriented preexisting basement fault. The Washita Valley Fault formed as a near-vertical segment cutting through the earlier fold-thrust structures. Movement was accompanied by oblique normal slip allowing grabens to develop that were subsequently filled with Virgilian-age sediment. A left step of the Washita Valley Fault allowed for a significant graben to develop near the east end of the study area resulting in a thick Virgilian-age growth section validating the timing of the fault movement. The Wichita Mountain Fault also underwent a component of left-lateral strike-slip displacement during the Late Pennsylvanian highlighting its continuous movement and deformation history in a rotating stress field. Although much of the published literature on the Washita Valley Fault is limited to the Arbuckle Uplift, our study documents its subsurface architecture, timing, and structural history in the southeast Anadarko Basin using a modern 3D seismic data set in relation to evolving Pennsylvanian tectonics.

Interpretation of the Reagan Fault, Garvin, Johnston, Murray, and Stephens Counties, Oklahoma

The Reagan fault, which lies between the Mill Creek syncline and the Tishomingo anticline, is one of the major faults in the Arbuckle Mountains. The fault's surface expression extends for more than 24 mi, and it can be traced in the subsurface at least an additional 26 mi west. The relative upthrown side of the fault changes at least four times along its length and it is manifest in different segments as both an apparent reverse fault and an apparent normal fault. Subsurface cross sections show abrupt facies changes within formations across the Reagan fault and isochore maps of individual units indicate a large-scale component of left-lateral movement along the fault. The geometry of the fault, as well as its displacement, also is consistent with a wrench-fault interpretation of the Reagan fault. Synorogenic conglomerates indicate that in at least one locality the Reagan fault had ceased movement, whereas the Washita Valley fault was still active.

Paleozoic Structure of the Central Basin Uplift and Adjacent Delaware Basin, West Texas (1)

Structural cross sections and a regional tectonic map show that the Central Basin uplift consists of upthrust blocks of alternating vergence. The uplift is separated from the adjacent Delaware basin by a major fault that changes throw and structural style along strike, accompanying changes in block vergence found along the uplift. The west-facing basement blocks were thrust westward over the Delaware basin, whereas the adjacent blocks face eastward. The distribution and style of structures suggest that small amounts of left-lateral movement occurred along west-trending and northwest-trending faults that separated rising blocks of the uplift. Transfer of lateral movement from vertical, west-trending faults on the Central Basin uplift and the Ozona arch to the west-trending Mid-basin fault in the Delaware basin rotated blocks of the uplift in a clockwise sense. Faults and folds within the study area have trends and slip directions that are generally similar to those within the Reagan and Washita Valley fault zones in the Arbuckle uplift adjacent to the Anadarko basin. The difference in the style of deformation between the two uplifts relates to varied angular relationships between preexisting structure and the direction of late Paleozoic stress. The identity of structural trends within these two uplifts suggests that other late Paleozoic basins and uplifts of the Ancestral Rocky Mountains may have formed in a similar stress field and that crustal rotation was pervasive along the southwestern margin of the continent during the late Paleozoic Ouachita-Maratho deformation.

Thermal Maturation by Vitrinite Reflectance of Woodford Shale, Arbuckle Mountains, Oklahoma: ABSTRACT

Vitrinite reflectance was measured on 40 grab samples from outcrops of the Woodford Shale (Upper Devonian-Lower Mississippian) collected near the Washita Valley fault in the Arbuckle Mountains in south-central Oklahoma. Samples are widely distributed along 40 km. Sample localities range from 60 m to 7.63 km from the Washita Valley fault. Well-indurated shale samples were collected from below the outcrop surface to reduce the effect of weathering on vitrinite reflectance. Vitrinite reflectance values were measured from standard kerogen concentrate pellets. Implications of the data specific to the Arbuckle Mountains include the Woodford Shale is immature to marginally mature with respect to the generation of liquid hydrocarbons; high heat flow associated with the rifting stage of the southern Oklahoma aulacogen was diminished by Late Devonian; the Woodford Shale was never deeply buried; and frictional heating from the Washita Valley fault did not affect the temperature field significantly.

Fracture Density and Spacing Along Washita Valley Fault, Arbuckle Mountains, Oklahoma: ABSTRACT

The authors document fracture density and spacing associated with the Washita Valley fault, a major strike-slip fault. The Washita Valley fault strikes northwest-southeast with up to 80 mi of exposure in southern Oklahoma and may be an early bounding fault of the Southern Oklahoma aulacogen (Ardmore/Marietta basins). Horizontal displacement on the fault has been estimated to be up to 40 mi, with vertical displacement on the order of 10,000 ft. Samples collected from traverses across the Washita Valley fault have been analyzed. The traverses cross the fault at different stratigraphic levels from Proterozoic igneous basement, through the Cambrian-Ordovician Arbuckle Group, Ordovician Simpson and Viola Groups, to the Silurian-Devonian Hunton Group. Several types of fracture systems are documented that reflect mechanical stratigraphy, burial depth during deformation, and episodic movement on the fault. The fractures in the study area include open fracture systems, calcite-filled fractures, tension gashes, and fractures related to pressure solution. The samples were cut parallel to the strike of the fault, vertical-normal to the fault, and horizontal-normal to the fault. These cuts allow examination of the total fracture strain, characterization of the fractures, and statistical analysis of fracture density. From these data, fracture density is shown to decrease exponentiallymore » moving away from the primary fault zone. The increased understanding of fracture patterns and characteristics will assist future exploration and development programs involving carbonate reservoirs associated with strike-slip systems.« less

Are Active Mid-Plate Fault Zones of the Central United States Interconnected?

Abstract It is generally assumed that faults in mid-plate regions, such as central and eastern United States (CEUS), unless historically active, are inactive and/or lack a potential for large earthquakes. The Meers fault in Oklahoma, located in an historically aseismic area, is a spectacular exception to this rule. Paleoseismic studies of this fault show that the most recent large event occurred about 1200 years ago, had a magnitude of more that MS = 7 or 7.5, a surface rupture of 40 km length, and several meters of net displacement on a major left-lateral fault (Ramelli and Slemmons, in press). At least four fault zones in other parts of CEUS indicate that the Meers faulting event is not unique, including: (1) New Madrid epicentral region with three events of about MS = 8 in 1811 and 1812 with surface faulting and deformation (Russ, 1982), (2) Washita Valley fault (Cox and VanArsdale, 1986), (3) Kentucky River fault (VanArsdale, 1986), and possibly (4) faulting near Pierre, South Dakota (Nichols and Collins, 1987). Moreover, such midplate active faults are not unique, for there are at last four similar examples of historical seismogenic faulting (McCue and others, 1987) with earthquakes of up to 6.9 magnitude. Most active fault zones can be dearly demonstrated to be parts of branching or interconnected tectonic systems, implying transfer of stress and strain along zones of deformation. We speculate that tectonically active mid-plate fault zones may also be parts of much longer, interconnected active systems, rather than isolated “hot spots” of activity resulting solely from the response of local crustal flaws to a regional stress field.

Surface and Subsurface Structural Analysis of a Part of Washita Valley Fault Zone, Southern Oklahoma: ABSTRACT

The Washita Valley fault zone is one of the major northwest-trending structures in southern Oklahoma. This fault system is believed to have originated as a series of normal faults during the formation of the southern Oklahoma aulacogen by late Precambrian or early Cambrian time and to have been reactivated during the Arbuckle orogeny in the Pennsylvanian. Descriptions of movement along the Washita Valley fault zone during Pennsylvanian deformation include numerous interpretations, the most common being left-lateral strike slip with 30-40 mi (50-65 km) of displacement. Structures in the area, however, suggest an alternate model. A detailed field study of small folds, faults, fracture arrays, slickensides, and drainage patterns was conducted along the southeastern half of the Washita Valley fault zone. An attempt has been made to relate these small-scale features to the major structures in the area to determine the orientation of the major compressive stress during deformation and the relative amounts of strike-slip vs. reverse dip-slip movement along the fault zone. Exploration for oil and gas along the Washita Valley fault zone has identified several overturned folds and repeated sections. Field observations in the study area include small drag folds and thrust faults parallel to the trend of the Washita Valley fault zone. The two major anticlines in the area, the Arbuckle and the Tishomingo, are both nearly parallel to the trend of the fault zone. These data suggest a model of deformation involving a large component of reverse dip-slip faulting with major duplication of strata. End_of_Article - Last_Page 514------------

Gravity Slide Thrusting and Folded Faults in Western Arbuckle Mountains and Vicinity, Southern Oklahoma

Documentation for one or more major gravity slide thrusts and numerous lesser slides is recognized in the Eola, Southeast Hoover, and Southwest Davis oil fields, and in the Western Arbuckle Mountains, Garvin and Murray Counties, Oklahoma. The gravity slide area initially covered portions of at least nine townships; it was more than 30 mi (50 km) long and 5 to 6 mi (8 to 10 km) wide. It involved a stratigraphic sequence > 5,000 ft (1,500 m) extending from the lower Springer Formation into the upper portion of the Arbuckle Limestone. The major slides moved to the northeast and northwest, probably in Middle Pennsylvanian. The slides and the faults were subsequently isoclinally folded in Late Pennsylvanian. Small depositional structures within beds ranging from upper Arbuc le through the Viola Limestone indicate the area was seismically active during deposition and probably also was subject to gravity sliding in the early Paleozoic. The tensional updip segment of the major folded slide fault now coincides with the trace of the Washita Valley fault. The compressional end of the slide coincides with the Reagan fault in the east and the frontal Eola fault in the west. In the Lake Classen area the latest folding has turned all the formations involved in the slide, and the associated faults, to a near-vertical position. Thus, the slide is exposed in a profile view on the south limb of the overturned Washita Valley syncline. On the north normal limb of the Washita Valley syncline, the slide is exposed in plan view, with the Dougherty anticline and related fo ds representing compressional folding at the toe of the slide. The major slide fault and the Washita Valley fault now share the same trace, but separate movements are still recognizable, the slides having moved north, northeast, and northwest followed by thrusting and probably left-lateral displacement along the Washita Valley fault. Compressional folding and thrusting in the toe of the slide, and extensional faulting along the trailing edge are both recognized. Several tectonic breccias near the top of the Kindblade Formation of the Arbuckle Group probably mark the orogenic event. Tectonic breccias within the fault zone also are interpreted in several wells in the Eola field, and in the past have been identified as Eola conglomerate (Pontotoc). The Arbuckle Group, which had been beneath at least 5,000 ft (1,500 m) of younger strata, was exposed immediately following the slide, which explains the inclusion of boulders and cobbles of this group of formations as major constituents in the earliest known Middle Pennsylvanian conglomerates in this area. The interpretation also explains the absence of any record in the geologic column of the sequential erosion of strata overlying the Arbuckle Group.

Washita Valley Fault System--A New Look at an Old Fault: ABSTRACT

With the application of plate tectonic concepts to southern Oklahoma, the structural style has more recently been characterized as a wrench fault system. In particular, the Washita Valley fault (WVF) is generally considered by many geologists to be a major left-lateral strike-slip fault with an offset of approximately 40 mi (64 km). The map most commonly used to demonstrate this magnitude of lateral offset is the basal Oil Creek sand distribution map. The zero edge of the basal Oil Creek sand provides the necessary piercing point to judge lateral offset along the WVF. However, the published basal Oil Creek map depicts the present-day distribution of the sand which is the result of cumulative movements since the deposition of the basal Oil Creek sand. Individual orogenic episodes must be sorted to determine what contribution possible strike-slip movements have made toward the present-day basal Oil Creek sand distribution. To unravel these various orogenic episodes a palinspastic restoration must be made. In such a sequential restoration, the last movement should be restored first or the known movements restored first to determine the unknown movements. In this presentation, the observable folds along the WVF have been unfolded and the known reverse faults have been restored to a pre-fault position. When this has been accomplished the partly restored basal Oil Creek sand map may be used to determine the amount of lateral offset on the WVF. The resulting restoration indicates that the commonly quoted figure of 40 mi (64 km) of lateral offset is too large. Surface and subsurface data demonstrate that the crustal shortening represented by folds and reverse faults alone can account for the present-day basal Oil Creek sand distribution and thus very little strike-slip movement is needed along the Washita Valley fault system. End_of_Article - Last_Page 1496------------

Structural Relations of Arbuckle and Ouachita Facies: ABSTRACT

Rocks of the Ouachita facies are thrust out over the Arkoma basin. As expected, part of the crustal shortening is taken up in the Arkoma basin by folding parallel with the strike of the thrust faults. This shortening can be observed in the outcrops. Unfortunately, the intersection of the Ouachita front with the Arbuckle Mountains, the Ardmore basin, and the Marietta-Sherman basin is covered by the Cretaceous overlap. Therefore, the relation of the Ouachita facies with the Arbuckle facies can be determined only by subsurface information. There is a regional southwest trend to the Ouachita front from where it disappears beneath the Cretaceous northeast of the Arbuckle Mountains to the Llano uplift in central Texas, indicating, in general, that the Ouachita facies was thrust from the southeast. In the Ardmore and the Marietta-Sherman basins there are no indications of thrusting from the southeast. Rocks of the Ouachita facies are in contact with the Arbuckle facies by means of northwest-trending, high-angle reverse faults. The trend of folding in these basins is also northwest, with no northeast trending folding as one would expect in front of a thrust from the southeast. The Ardmore and Marietta-Sherman basins are characterized by large northwest-trending strike-slip faults. The best examples of these are the Reagan and Washita Valley faults which bound the Tishomingo uplift on the northeast and southwest, and the Mannsville-Madill-Aylesworth fault which parallels the Washita Valley fault. It is concluded that in the Ardmore and Marietta-Sherman basins, the Ouachita facies is not in contact with Arbuckle facies by means of low-angle thrusting, but instead the Ouachita rocks have been shoved from the southeast in northwest-trending wedges. This action drove blocks of Arbuckle facies into confined spaces on the northwest and caused great crustal shortening along a southwest-northeast line resulting in the northwest trending structures of the Ardmore and Marietta basins. End_of_Article - Last_Page 1822------------

Wrench Fault Movements Along Washita Valley Fault, Arbuckle Mountain Area, Oklahoma: GEOLOGICAL NOTES

Wrench Fault Movements Along Washita Valley Fault, Arbuckle Mountain Area, Oklahoma: GEOLOGICAL NOTES

Structural Geology of Arbuckle Mountain Region: ABSTRACT

Structural Geology of Arbuckle Mountain Region: ABSTRACT