Murray County Research Articles

High-resolution stratigraphic characterization of natural fracture attributes in the Woodford Shale, Arbuckle Wilderness and US-77D Outcrops, Murray County, Oklahoma

Natural fracture aperture-size, spacing, and stratigraphic variation in fracture density are factors determining the fluid-flow capacity of low-permeability formations. In this study, several facies were identified in a Woodford Shale complete section. The section was divided into four broad stratigraphic zones based on interbedding of similar facies. Average thicknesses and percentages of brittle and ductile beds in each stratigraphic foot were recorded. Also, five fracture sets were identified. These sets were split into two groups based on their trace exposures. Fracture linear intensity (number of fractures normalized to the scanline length [[Formula: see text]]) values were quantified for brittle and ductile beds. Individual fracture intensity-bed thickness linear equations were derived. These equations, along with the average bed thickness and percentage of brittle and ductile lithologies in each stratigraphic foot, were used to construct a fracture areal density (number of fracture traces normalized to the trace exposure area [[Formula: see text]]) profile. Finally, the fracture opening-displacement size variations, clustering tendencies, and fracture saturation were quantified. Fracture intensity-bed thickness equations predict approximately 1.5–3 times more fractures in the brittle beds compared with ductile beds at any given bed thickness. Parts of zone 2 and almost entire zone 3, located in the upper and middle Woodford, respectively, have high fracture densities and are situated within relatively organic-rich (high-GR) intervals. These intervals may be suitable horizontal well landing targets. All observed fracture cement exhibit a lack of crack-seal texture. Characteristic aperture-size distributions exist, with most apertures in the 0.05–1 mm (0.00016–0.0032 ft) range. In the chert beds, fracture cement is primarily bitumen or silica or both. Fractures in dolomite beds primarily have calcite cement. The average fracture spacing indices (i.e., bed thickness-fracture spacing ratio) in brittle and ductile beds were determined to be 2 and 1.2, respectively. Uniform fracture spacing was observed along all scanlines in the studied beds.

The use of chemostratigraphy to refine ambiguous sequence stratigraphic correlations in marine mudrocks. An example from the Woodford Shale, Oklahoma, USA

Application of sequence stratigraphy to fine-grained lithologies has previously been hindered by the difficulty of identifying distinct facies shifts within mudrocks. Three cores from Lincoln, Pottawatomie and Pontotoc Counties in Oklahoma and two outcrops at the Hunton Anticline Quarry in Murray County, OK record both proximal and distal regions of the Arkoma Basin. Handheld X-ray fluorescence data and gamma-ray profiles together with lithological descriptions can be used to develop sequence-stratigraphic interpretations. Stratigraphic successions that are challenging to correlate based on gamma-ray (GR) profiles alone can be correlated accurately by utilizing surfaces that are recognized within chemostratigraphic profiles. Within the Arkoma Basin, Oklahoma, the chemostratigraphic profile of the Woodford Shale is interpreted within a sequence-stratigraphic framework using the following general criteria. The Lowstand Systems Tract (LST) is defined by increasing concentrations of Ti, Zr, Al and K as well as high levels of Mo and V. The Transgressive Systems Tract (TST) is defined by declining concentrations of Ti and Zr, although Al and K may remain elevated; Mo and V also show general declines. The Highstand Systems Tract (HST) is defined by increasing concentrations of Ti, Zr, Al and K, but is distinguished from the LST by low levels of Mo and V. Supplementary material: Chemofacies profiles are available at http://doi.org/10.6084/m9.figshare.c.2849599 .

Draining the Great Oasis: An Environmental History of Murray County, Minnesota. Edited by Anthony J. Amato, Janet Timmerman, and Joseph A. Amato. Marshall, Minn.: Crossings Press. 2001. xix + 232 pp. Illustrations, tables, maps, notes, bibliography. Cloth $25.00, paper $15.00

<i>Draining the Great Oasis: An Environmental History of Murray County, Minnesota.</i> Edited by Anthony J. Amato, Janet Timmerman, and Joseph A. Amato. Marshall, Minn.: Crossings Press. 2001. xix + 232 pp. Illustrations, tables, maps, notes, bibliography. Cloth $25.00, paper $15.00

Source of Shallow Simpson Group Oils in Murray County, Oklahoma: ABSTRACT

Source of Shallow Simpson Group Oils in Murray County, Oklahoma: ABSTRACT

Larval Stages of Renicolid Trematodes

Diameter (exclusive of processes) of vesicle of holotype 63 ,/; process length ranges from 65-87 u. REMARKS: Orthosphaeridium vibrissiferum n. sp. is similar to 0. insculptum Loeblich from the Upper Ordovician Sylvan Shale of Oklahoma but differs in its slightly smaller size, in the surface ornamentation of small granulose spines rather than the prominent grana, and in having fewer processes. DERIVATION OF NAME: From Latin vibrissa, whisker, stiff tactile hair + fero, carry, bear. TYPES AND OCCURRENCE: Holotype, 67-94(1474) and paratype, 67-95(SEM 2611-2615) from the Middle Ordovician Mountain Lake Member of the Bromide Formation below the spillway at the northernmost of two small lakes dammed on Spring Creek, NE/4, Sec. 17, T.2S., R.1W., Murray County, Oklahoma. Collected by H. T. and A. R. Loeblich, Jr.

The Short-Tailed Shrew, Blarina Brevicauda, in Oklahoma

Two subspecies of the short-tailed shrew, Blarina brevicauda caro- linensis and Blarina brevicauda hulophaga, have been reported from Oklahoma. Study of Oklahoman specimens reveals that all are referable to a single subspecies, B. b. carolinensis, with the later-named B. b. hulophaga as a synonym. Clinal vari- ation in Blarina brevicauda in Oklahoma and several surrounding states is discussed, and records of the species in Oklahoma are summarized. Few specimens of the short-tailed shrew, Blarina brevicauda, are on record from Oklahoma. Those reported have been assigned to the sub- species B. b. carolinensis or to B. b. hulophaga. Shrews from the Ar- buckle Mountains have been referred to hulophaga, type locality east of Dougherty, in Murray County, Oklahoma, whereas shrews from elsewhere in the state usually have been referred to carolinensis, type locality in eastern South Carolina (see Blair, 1939:99, and Hall and Kelson, 1959:53-54). Assignment of 'Oklahoman specimens of Blarina to subspecies has been mainly on the basis of color; those from the Arbuckle Mountains are allegedly paler. Blair (loc. cit.), for example, remarked concerning hulophaga: This race is known from only 4 specimens, all of which agree in being paler and more brownish in color than the race caro- linensis. In size and cranial characters it does not differ appreciably from carolinensis. It seems likely that this is a slight local race, de- veloped through partial isolation in the Arbuckle Mountains. We have seen three of the four specimens mentioned by Blair (lectotype not seen) and five specimens from Platt National Park, Murray County, all of which, considering age and season of capture, can be matched exactly in color by specimens from other parts of Oklahoma and also by specimens from Kansas and southern Nebraska. In ac- cordance with Blair, we find no significant differences in size between specimens from the Arbuckles and those from elsewhere in Oklahoma, nor do we discern any other differences between these shrews. We conclude, therefore, that they represent one subspecies.

Thrust Faulting in Arbuckle Mountains, Oklahoma

There are thirteen erratic masses superimposed on Simpson strata ranging in age from the Oil Creek formation to the Bromide formation south of the city of Sulphur, Murray County, Oklahoma. The rocks of the erratic masses range in age from the McLish formation to the Trenton formation. Their occurrence has not been previously recognized. The stratigraphy and structural history of the area and the possibilities of the origin of the erratic masses are discussed. It is concluded that these erratic masses are outliers of an overthrust sheet. The overthrust, from the southwest, occurred in post-Hoxbar-pre-Pontotoc time and overrode the truncated beds of the Simpson group. In short, the erratic masses are klippen.

Position of Cambrian-Ordovician Boundary in Section of Arbuckle Limestone Exposed on Highway 77, Murray County, Oklahoma: DISCUSSION

Position of Cambrian-Ordovician Boundary in Section of Arbuckle Limestone Exposed on Highway 77, Murray County, Oklahoma: DISCUSSION

Notes from Murray County, Oklahoma

Notes from Murray County, Oklahoma