Bangor Limestone Research Articles

Chester and Pottsville Depositional Systems, Outcrop and Subsurface, in Black Warrior Basin, Mississippi and Alabama: ABSTRACT

ABSTRACT Terrigenous clastic depositional systems of the Upper Mississippian Chester Group and the overlying Lower Pennsylvanian Pottsville Group in the Black Warrior basin of Alabama and Mississippi were deposited in distinctly different tectonic settings. The predominantly deltaic Chester sandstone units accumulated on the stable northern shelf of the basin and had a cratonic source to the north or northwest. Detailed subsurface mapping of these cratonic delta systems indicates that the northern shelf can be subdivided into a terrigenous clastic western element (Parkwood and Floyd Formations) and a largely carbonate eastern element (Bangor, Hartselle, Monteagle, and Pride Mountain Formations). Total thickness of the Chester interval on the shelf averages 1,200 ft. Pottsville sediments, in contrast, had a principal source to the southwest of the Black Warrior basin. They represent the thick clastic wedge shed from the Ouachita orogenic belt. Pottsville deposition occurred in a rapidly subsiding foreland basin and involved a maximum sediment accumulation exceeding 12,000 ft in the basinal core. With the Chester group four cycles of deltaic progradation have been identified through data gathered from 600 well logs. Individual genetic intervals between the Tuscumbia Limestone and the base of the Pennsylvanian System are bounded by thin marine transgressive carbonate units. Two deltaic depocenters, a carbonate shelf and ramp, and a shallow basin carbonaceous shale unit comprise the principal depositional systems along the northern margin of the basin. The lowest interval (Lewis) involves a high-constructive lobate delta system whose maximum sandstone axes extend southeastward from Lee and Itawamba Counties, Mississippi, as far as Tuscaloosa County, Alabama. Maximum net sandstone thickness for each of the four lobes is approximately 60 ft. The second interval includes two distinct subdelta complexes of roughly the same age: the Evans High-Destructive Wave-Dominated Delta System on the western side of the northern shelf and the more easterly Hartselle High-Destructive Wave-Dominated Delta system in northwestern Alabama. The Hartselle net sandstone isolith pattern evidences a pronounced northwest-southeast elongation parallel to the shelf edge. Based on outcrop work, some researchers have interpreted the Hartselle as being a barrier bar system. Overlying the Hartselle-Evans genetic unit are the laterally equivalent Muldon Delta complex (Mississippi) and Bangor carbonate shelf (Alabama). The Muldon system is a thick (up to 450 ft of net sandstone), multistoried, high-constructive elongate group of delta lobes that takes in the subsurface Rea, Abernathy, Sanders, and Carter Sandstones. Further to the east, Bangor Limestone thicknesses in excess of 600 ft occur over interior portions of the shelf. Despite this build up, no true shelf edge or slope systems developed. In the interval between the Millerella Limestone and the top of the Mississipian System, there is a fourth Chesterian delta cycle. The distal edge of an extensive Pennington Delta, having an Appalachian source, prograded into northeastern Alabama. Further to the west, the Gilmer high-constructive delta system marks the last Paleozoic cratonic delta system laid down on the northern shelf. With the surface and shallow subsurface Pottsville of the Black Warrior basin in Alabama, the 2,000 ft stratigraphic interval can be subdivided into a minimum of seven vertical genetic components. In contrast with the Chester units, however, laterally extensive coal seams rather than marine transgressive limestone tongues form the bounding elements. On the surface, the lowest Pottsville unit has no productive coal seams and is dominated by massive, quartz-arenite sandstone bodies interbedded with dark gray shale. These rock units record the presence of a basal Pennsylvanian microtidal barrier bar system and associated lagoon. Higher, in genetic intervals 2 through 4, the leading edge of the northward-prograding Ouachita clastic wedge reached north Alabama. It is preserved as prodelta mudstone, bar finger sands, crevasse splay units, destructional sheet sand, and delta plain facies of high-constructive deltas. Intervals 5, 6, and 7 contain a greater quantity of conglomeratic debris. Coals are less numerous, but commonly thicker in this proximal deltaic setting than with the distal delta. Petrographically, the upper Pottsville sandstone bodies are phyllarenites and polylitharenites (metamorphic, volcanic, and sedimentary rock fragments) and contain significant quantities of vein quartz and chert. Careful petrochemical study of the Pennington Delta, subsurface Lewis, Evans, and Muldon systems, and the Pottsville detaic facies should be able to document the respective Appalachian orogenic, cratonic, and Ouachita orogenic source areas for these three distinct Carboniferous terrigenous clastic elements of basinal fill in the Black Warrior basin.

Quantification of shape by use of Fourier analysis: the Mississippian blastoid genus Pentremites

Psychological evidence suggests that the visual outline of an object is the most important character for discriminating differences in external morphology. External morphology is an important taxonomic character in describing living and fossil species, for example, the blastoid Pentremites. Comparison of different views of the same specimen utilizing Fourier series suggests that the skeleton of Pentremites commonly is not rotationally symmetrical and that the asymmetry is not associated with any specific ray. Analysis of a growth series indicates that the amplitudes of the second and third harmonics are significantly correlated with growth, which is demonstrated to be anisometric. Definable changes in the lateral outline can be attributed to changes in harmonic amplitudes and a wide range of morphological forms comparable to known taxa can be generated by systematically varying the amplitudes of the first four harmonics. The population used in this study probably represents Pentremites robustus Lyon and is from Bangor Limestone in the abandoned Moulton Quarry, Lawrence County, Alabama.

Deposition, Facies Patterns, and Hydrocarbon Potential of Bangor Limestone (Mississippian), Northern Black Warrior Basin, Alabama and Mississippi: ABSTRACT

Abstract The Bangor Limestone was deposited as a carbonate shelf, ramp and basin sequence on the northeast flank of the Warrior Basin. Progradation to the southwest was episodic and resulted in several cyclic units which grade upward from deeper water muddy facies into grainy shoal facies. Shoal facies regression eventually expanded the shelf more than 14 miles basinward. The Bangor can be divided into three members which are mappable throughout the shelf and ramp. Each member contains a shelf-blanketing, grain-support facies rich in crinoids, bryozoans and oolites. Widely scattered patches of porous reservoir-quality lime occur in this shallow water suite; however, there are no indications of broad porosity pockets which might serve as large stratigraphic traps on the shelf. Known gas accumulations on the Bangor shelf, i.e., Whitehouse and Nauvoo Fields, appear to be low-relief closures having small reserves. Future discoveries are anticipated to be analogous to these. Small potential reserves and probable inability to seismically detect the low-relief structures make the shelf an unattractive objective. The Bangor ramp may offer better hydrocarbon potential. One speculative ramp model is presented which suggests the possibility of bryozoancrinoidal mounding. Suggested mound-trap closure could reach 100 to 150 feet. If such mounds were densely spaced or areally large, hydrocarbon reserves could be attractive.

The oolitic limestone deposits of Franklin County, Alabama

For three-quarters of a century, Oolitic limestone has been quarried in the Franklin County, Alabama, district, for building purposes. The stone occurs in two horizons within the Bangor limestone formation of Subcarboniferous age. At present, the commercial stone appears to be confined to Franklin County within a belt some fifteen miles in length, centering around Russellville.

Sinkholes of the Cumberland Plateau

In a recent paper' Paris B. Stockdale has described an unusual sinkhole occurring in the sandstones near the eastern escarpment of Walden Ridge, at a considerable stratigraphic distance above the Bangor limestone. The origin of this sinkhole, known as Montlake, is believed to have been the collapse of a great thickness of shale and sandstone into a cave developed by normal solution in the Bangor limestone. Although this sinkhole is probably the most striking example of its type, it is but one of a number of similar sinkholes known to occur in the Cumberland Plateau and Walden Ridge. A similar, though smaller, sinkhole is present in Bledsoe County, Tennessee, at the western escarpment of Walden Ridge, at the head of a small hollow, tributary to Sequatchie Valley. This sinkhole is shown on the Pikeville Special Quadrangle and is located about 4 miles east of Pikeville, in the south-central portion of the central rectangle, just west of the headwaters of Coalbank Creek. It is about 60 feet deep, with a steep, clifflike eastern wall, but with a gentler slope on the western side. Although the Sewanee conglomerate, which forms the crest of Walden Ridge and the walls of the sinkhole, dips gently eastward, the western rim of the sinkhole is slightly lower than the eastern rim, and it contains many large blocks of Sewanee conglomerate, which have irregular dips. There is no permanent lake in this sinkhole, as is the case at Montlake, but all the drainage is definitely toward it, and a small stream entering from the east wall disappears into the bottom. No spring was found to emerge at any similar elevation along the escarp-

Spores from the Pennington Coal, Rhea County, Tennessee

The Pennington coal, which is exposed in the floor of Cranmore Cove, Rhea County, TIennessee, occurs as a thin vein, with a maximum thickness of 52 inches. This coal lies approximately 100 feet above the Bangor limestone of the Chester series and about 350 feet below the Gizzard formation of the lower Pottsville, and is considered as Lower Carboniferous (Mississippian) in age; though there is no definite break either above or below. The coal is locally mined but as far as I know there are no published analyses of it.

The Great Glass-Sponge Colonies of the Devonian; Their Origin, Rise, and Disappearance

Previous articleNext article FreeThe Great Glass-Sponge Colonies of the Devonian; Their Origin, Rise, and DisappearanceJohn M. ClarkeJohn M. Clarke Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The Journal of Geology Volume 28, Number 1Jan. - Feb., 1920 Article DOIhttps://doi.org/10.1086/622694 Views: 180Total views on this site Citations: 5Citations are reported from Crossref PDF download Crossref reports the following articles citing this article: Age and tectonic significance of diamictites at the Devonian–Mississippian transition in the central Appalachian Basin, (Jan 2020): 79–103.https://doi.org/10.1130/2020.0057(04)Frank R. Ettensohn*, Geoff Clayton, R. Thomas Lierman†, Charles E. Mason, Federico F. Krause, Christopher DeBuhr, Thomas B. Brackman, Eric D. Anderson, Allen J. Dennis, Jack C. Pashin Late Devonian lonestones, diamictites, and coeval black shales from the Appalachian Basin: Discerning relationships and implications for Late Devonian Appalachian history and glacially driven seafloor anoxia, (Jan 2020): 67–88.https://doi.org/10.1130/2020.2545(05)Linda Hernick Edwin Bradford Hall: Devonian Sponge Collector Extraordinaire, Earth Sciences History 22, no.22 (Jan 2003): 209–218.https://doi.org/10.17704/eshi.22.2.t4m3388558qr2226J. Keith Rigby, Richard Keyes First report of hexactinellid dictyosponges and other sponges from the Upper Mississippian Bangor Limestone, northwestern Alabama, Journal of Paleontology 64, no.66 (Jul 2015): 886–897.https://doi.org/10.1017/S0022336000019983 REFERENCES, (Jan 1965): 393–445.https://doi.org/10.1016/B978-0-08-013596-0.50013-8