Ouachita Geosyncline Research Articles

Origin of Quartzarenites in Upper Mississippian and Lower Pennsylvanian of Appalachian Basin: ABSTRACT

Quartzarenites in the Upper Mississippian and Lower Pennsylvanian of the central Appalachian basin have been attributed to fluvial or beach-barrier depositional environments. As part of the USGS basin analysis program, we reevaluated existing data and concluded that quartzarenites were deposited primarily in a high-energy marine environment dominated by tidal currents. These deposits are linear, trend toward the southwest, and are roughly parallel to the axis of the Appalachian geosyncline. Herringbone structures and bioturbation are abundant in the upper part of the deposits and near their margins. The lower and central parts of the deposits commonly display unidirectional festoon cross-beds having amplitudes up to 1 m. Basal contacts tend to be sharp and erosional in th high-energy central parts but are gradational near the margins. The spatial relation of these sandstone deposits to marine facies, their widespread distribution, and their lateral continuity are more compatible with a marine-dominated rather than fluvial origin. Their textural and mineralogical maturity also indicates winnowing typical of a high-energy marine system. Sedimentary structures typical of beach deposits or fluvial systems are rare. These sandstones were apparently deposited in an epicontinental seaway, which, at times, may have been open at both ends. Because of the configuration of the basin, tidal and geostrophic energies were dominant over wave energy; tidal basin deposits predominated, and wave-energy beach-barrier deposits were rarely preserved. Ebb flow carried the winnowed fines into the southwestern part of the Appalachian basin or into the Ouachita geosyncline. Similar hydrodynamics and sediment transport occur today on the Sunda Shelf, the Bay of Fundy, and in the Bering Sea. End_of_Article - Last_Page 1434------------

A Channelized, Sand-Rich, Deep-Sea Fan Deposit, Lower Atoka Formation (Pennsylvanian), Ouachita Mountains, Oklahoma and Arkansas: ABSTRACT

The lower member of the Pennsylvanian Atoka Formation exposed in the Ouachita Mountains of Oklahoma and Arkansas is part of a thick (more than 10,000 m or 32,800 ft) turbidite sequence deposited in a remnant ocean basin (the Ouachita geosyncline) during the Carboniferous. Paleocurrent data indicate a predominantly longitudinal sediment dispersal pattern westward down the basin axis. Nine lithofacies are recognized: massive, amalgamated sandstones (A1), graded, matrix-supported sandy mudstones (A2), six different types of classic turbidites (C1, C2, C3, D1, D2, and D3), and chaotic deposits (F) including debris flows. These occur in two principal lithofacies associations, both representing deposition in an areally extensive, sand-rich, channelized deep-sea fan environment. Lithofacies association 1 consists of packages of lithofacies A1 (and to a lesser extent A2 and C3) 1-30 m (3-98 ft) thick, interbedded with intervals comprised of lithofacies A2, C1, C2, C3, D1, D2, and D3, in which the sandstone:shale ratio is generally high (amalgamated to 1:5). Thickening- and thinning-upward sequences are arranged symmetrically about the lithofacies A1 packages, producing s acked symmetrical sequences 1 to 20 m thick. Lithofacies association 2 consists of lithofacies C3, D1, D3, and minor amount of D2, arranged in symmetrical as well as individual thickening- and thinning-upward sequences 1-40 m (3-130 ft) thick. The sandstone:shale ratio is highly variable (amalgamated to 1:50). Although thickness trends in this lithofacies association can be highly complex, thinning-upward sequences (10-40 m or 33-130 ft thick) are prominent. Slumped chaotic deposits (lithofacies F) are intercalated throughout both lithofacies associations. Common crevasse splays that develop into new channel segments, and filling of distributary channels are the inferred processes involved in the development of the two lithofacies associations. The absence of deposits of major depositional lobes and the extensive development (both vertically and laterally) of a channelized (distributary channel) fan environment suggest that current submarine-fan models are not generally applicable to this deposit. End_of_Article - Last_Page 531------------

Rb-Sr Dating of Illite Diagenesis: ABSTRACT

In the Woodford Shale (Upper Devonian), apparent Rb-Sr ages decrease as clay grain size decreases, which in turn correlates with increasing abundance of diagenetic illite. Analyses of the fine-clay size fraction (< 0.2µ) from widely spaced wells in the Delaware basin of west Texas, plot on a single isochron indicating an age of 300 ± 4 m.y. (Middle Pennsylvanian). At this time the Woodford was buried only 200 to 600 m; consequently diagenesis must have been triggered by a circumstance other than deep burial. Possibly diagenesis was accomplished by hydrothermal fluids moving toward the craton out of the Ouachita geosyncline, which at that time was experiencing horizontal compression. These fluids may have been responsible for petroleum migration and lead-zinc ineralization. In the Frio Formation (Oligocene) of the Texas Gulf Coast, samples of fine clay-size material (< 0.06µ) from the 3 to 5 km depth interval in a single well also provide a well-defined isochron corresponding to 21.6 ± 2.2 m.y. Burial here was possibly so rapid that transformation of smectite to illite approximated an episodic event over the entire depth interval. Alternatively, because the sediment is geopressured, the age might record the time of geopressure development which was accompanied by a rapid rise in temperature. Clay diagenesis at the surface is illustrated by a paleosoil developed on Pennsylvanian shale in the Llano uplift of central Texas. The paleosoil was buried by Cretaceous basal conglomerate and records the time of marine transgression 119 ± 3 m.y. ago. Constituents of the shale were degraded by soil-forming processes which erased previous isotopic memory, then reconstituted by coming in contact with marine water. This field relation offers a new way to date directly a time of sedimentary deposition. End_of_Article - Last_Page 610------------

Evaluation of Brachiopod Faunas from Solis Limestone (Ordovician, Silurian, and Lower Devonian), Chihuahua, Mexico: GEOLOGIC NOTES

The Solis Limestone in Chihuahua, Mexico, was deposited across the margin of the Ouachita geosyncline. The northern part of the formation was deposited on a carbonate platform, the southern part on a slope leading into the Ouachita trough. An evaluation of the brachiopod faunas provides the basis for revision of correlations of the formation. On the north, in the Cerro de Placer de Guadalupe section, the formation is a thick sequence of Upper Ordovician and Silurian, relatively clean dolomitic limestone. Apparently these rocks were laterally continuous with the Fusselman Dolomite in Texas and New Mexico. In sections on the south the Upper Ordovician and Silurian part of the Solis Limestone is much thinner and is an argillaceous limestone; the major part of the formation h re is Early Devonian.

North American Geosynclines--Test of Continental-Drift Theory

North American Geosynclines--Test of Continental-Drift Theory

Stratigraphy of Everton Formation (Early Medial Ordovician), Northern Arkansas

The Everton Formation is an intertonguing complex of sandstone, limestone, and dolomite exposed in northern Arkansas; it has produced gas shows in the subsurface. The Everton lithologies outcropping in bluffs along the west-east trending Buffalo and White Rivers can be divided into seven laterally persistent members. Previous investigators named 4 members but were unaware of their regional relations within the Everton. Three new informal members are defined. The basal unit, the Sneeds Dolomite Member, disconformably overlies the Powell Dolomite (Canadian) and is laterally persistent. Members A and B consist of interbedded sequences of limestone and sandstone above the Sneeds. In the east, member A underlies a massive St. Peter-like sandstone known as the Calico Rock Sandstone Member, and, in the west, member B underlies the thick Newton Sandstone Member. Unnamed Everton dolomites include a medium crystalline dolomite facies, a late secondary replacement of limestone, exposed in the central part of the traverse, and a very finely crystalline dolomite facies with supratidal characteristics in the central and eastern parts of the traverse. Member C is a laterally persistent dolomitic sandstone-dolomite complex overlying the Newton sandstone n the west and the unnamed Everton dolomites in the central and eastern parts of the study area. The uppermost member, the Jasper, is also extensive and undergoes an eastward lithologic change from sandstone to limestone to dolomite. The units of the Everton lack an abundant macrofauna except for the limestone facies of the Jasper Member. The meager fauna, lithologies, and vertical and lateral relations of the members record deposition on a shallow, broad shelf. The carbonate rocks accumulated in shallow subtidal, lagoonal, and supratidal environments, whereas the quartz sands were deposited in barrier-island, chenier-plain, and shallow-subtidal environments. The basinal area was on the south in the Ouachita geosyncline, and the intermittently exposed craton that acted as the source area for the terrigenous material lay on the north. As a result of this study, the Everton can be correlated with equivalent deposits exposed in northeastern Oklahoma (Burgen Sandstone and lower and middle Tyner Formation). Tentative correlation with the Simpson Group of central and southern Oklahoma also is proposed.

Bathymetry and Paleoecology of Ouachita Geosyncline of Southeastern Oklahoma as Determined from Trace Fossils

Bathymetry and Paleoecology of Ouachita Geosyncline of Southeastern Oklahoma as Determined from Trace Fossils

Provenance of Johns Valley Boulders in Late Paleozoic Ouachita Facies, Southeastern Oklahoma and Southwestern Arkansas

Clasts within the Johns Valley Formation of the central Ouachita Mountain province range in age from Late Cambrian through Early Pennsylvanian; Ordovician specimens dominate. The clasts were derived from a single linear sourceland which was composed predominantly of foreland carbonate strata, but which also contained subordinate quantities of transitional and geosynclinal rock types. The sourceland was just north of the transitional zone along the flexure which separated the foreland and geosynclinal tectonic provinces. Boulder dispersal patterns indicate that the sourceland was a rising, fault-bounded geanticlinal ridge which became an emergent archipelago. Prominent islands of the archipelago functioned as major boulder dispersal centers, and transport was primarily southward down steep and unstable marginal paleoslopes of the Ouachita trough. Clasts were derived by both subaerial erosion of the archipelago under warm and humid climatic conditions and by submarine erosion of a marginal fault scarp. The boulders were transported only short distances from their source by a combination of mass-movement media that were active along the unstable marginal paleoslopes. The prolific introduction of boulders into the Ouachita geosyncline during deposition of the Johns Valley Formation resulted in the development of a distinct wild-flysch subfacies indigenous to the northern margin of the trough, in contrast to the turbidite flysch facies of the trough interior. After deposition of overlying Atoka sediments, the Ouachita facies was compressed and thrust-faulted northward over the denuded sourceland, the probable paleogeographic location of which is approximately coincident with the present Ouachita frontal belt.

Stratigraphy and Origin of Maravillas Formation (Upper Ordovician), West Texas

The Maravillas Formation is a distinctive chert-rich formation that was deposited in deep water on the slope and floor of the Ouachita geosyncline in West Texas. It is 40 percent black chert; 30 percent fetid calcarenite, micrite, and marlstone; 14 percent shale; 10 percent chert of other colors; 5 percent limestone-pebble conglomerate; and 1 percent dolomite. These rocks are intercalated in even beds, generally 3-12 in. thick. The formation ranges from 60 to almost 500 ft in thickness; isopach lines delineate a lens-shaped body whose axis (uncorrected palinspastically) is northeast-southwest and is parallel with tectonic strike. In the Marathon basin the formation is divided, from bottom to top, into three members: (1) limestone and chert, (2) chert and limestone, and (3) chert and shale. Members 1 and 2 differ chiefly in that limestone predominates in member 1 and chert predominates in member 2. In many places member 2 can be divided into three units. Member 3 is predominantly shale at the southern and eastern margins of exposures, and is the Solitario Formation of Baker and the Persimmon Gap Formation of Wilson. Calcarenite beds are composed of skeletal grains, intraclasts, pellets, and minor shale, chert, quartz, phosphate, and glauconite grains. Laminated, or graded and laminated, beds predominate. Micrite and marlstone are composed of compacted pelletal(?) and clayey pelletal(?) silt and mud. Conglomerate beds are composed of limestone and chert clasts derived from shelf equivalents of the Maravillas and older formations. Paleocurrent data and grain-size trends indicate that detritus was derived from the northwest. Calcarenite was deposited largely by turbidity currents; conglomerate was laid by turbidity currents, debris flows, and possibly nonturbid density currents; and micrite, marl, and clay settled as a rain of sediment from weak geostrophic or nonturbid density currents. The geometry and relict texture of chert lenses and beds prove that most chert is of replacement origin, but a few beds are altered siliceous ooze. Lumpy and chalcedony-veined black chert beds in member 2 formed as submarine slide deposits. The preservation of abundant organic material (3.7 percent organic carbon), including some petroleum, in some beds and the absence of bioturbation features indicated that sedimentation generally occurred in an euxinic environment. The grain size in the formation is generally coarser at the bottom and finer at the top, a response to a major epeirogenic pulse that affected the shelf northwest of the geosyncline. Deposition of clay and spiculitic clay continued after the influx of carbonate had ceased.

Trace Fossils, Basin Migration, Sedimentation, and Bathymetry of Ouachita Geosyncline of Oklahoma: ABSTRACT

Flysch-type Nereites trace-fossil associations, paleocurrent data, and relatively numerous, thick sandstone beds with fluted soles, graded tops, contorted and convolute lamination, and ripple-drift indicate a continuous deep-water (bathyal-abyssal) axis for the Ouachita geosyncline during the deposition of the Stanley Group, Jackfork Group, Johns Valley Shale, and Atoka Formation of Oklahoma. Eventual migration of the basin onto the shelf is suggested by the west, northwest, and north overlap of the Atoka Formation on the Johns Valley Shale, Springer Formation, Chickachoc Chert, and Wapanucka Limestone, and by a transitional, shoal- to deep-water facies developed over the Chickachoc Chert and Wapanucka Limestone in the Atoka Formation. The transitional facies consists of a thick shale which is thought, on the basis of modern analogues, to have been deposited on a slope. Thin sandstone beds are present in this shale and are more numerous upward in the section. The sandstone beds are characterized by a trace-fossil association similar to a trace-fossil association in the basin axis, and by tooled soles, contorted lamination, ripples, and little grading. Down-slope, the transitional facies grades into the axial facies in which thick-bedded, axial-type sandstone becomes dominant. North of the Ouachita Mountains in the Arkoma basin, the top of the Atoka Formation is preserved. Physical-sedimentary structures and molasse-type Cruziana trace-fossil associations indicate shoal and near-shoal conditions. Toward the base of the section, there is no evidence for intermediate or deep-water facies. The older transition and deep-water facies are concealed in the thick Atoka section of the Arkoma basin or are farther south, beneath the Choctaw thrust which borders the west, northwest, and north margins of the Ouachita Mountains. End_of_Article - Last_Page 711------------

New Evidence for Dating Carboniferous Flysch Deposits of Ouachita Geosyncline, Arkansas and Oklahoma: ABSTRACT

Ammonoids and other invertebrate fossils from the Stanley Shale, Jackfork Sandstone, and Johns Valley Shale provide new information on the ages and correlations of these three stratigraphic units. The Stanley Shale is Late Mississippian (Chesterian) in age through most of the Ouachita Mountains region, except for a basal part, approximately 75 ft thick, of probable Meramecian age. In Saline and Perry Counties, Arkansas, Pitkin Limestone fossils, most of them in reworked boulders, are present about 500 ft below the top of the Stanley. Near Little Rock, Arkansas, ammonoids in the upper part of the Stanley represent the Reticuloceras tiro zone of the lower Hale. The Jackfork Sandstone is of Early Pennsylvanian (Morrowan) age in Arkansas, but near Talihina, Oklahoma, its basal plant-bearing beds are of Late Mississippian (Chesterian) age. Cymoceras, an early Morrowan ammonoid genus, has been recognized in the lower part of the Jackfork near Amity, Arkansas. The Game Refuge Formation of Harlton at the top of the Jackfork has yielded Morrowan brachiopods and trilobites in Atoka County, Oklahoma. The Johns Valley Shale contains indigenous ammonoid assemblages representing the Branneroceras branneri, Axinolobus modulus, and Diaboloceras neumeieri zones. These three zones are present also in the type section of the Bloyd Shale, indicating a direct equivalence of the two formations. Masses of Caney Shale in the Johns Valley, some of them enormous, as well as boulders of Lower Ordovician to Lower Pennsylvanian rocks, were introduced largely by turbidity flow and gravity gliding. End_of_Article - Last_Page 719------------

Paleocurrents and Source Areas of Late Paleozoic Sediments of the Ouachita Mountains, Southeastern Oklahoma

ABSTRACT Late Mississippian and early Pennsylvanian flysch sediments of the Ouachita foldbelt of southeastern Oklahoma include turbidites with abundant sole marks and other paleocurrent indicators. Directional readings on sandstones of the Jackfork, Johns Valley, and lower Atoka sequence show that sediment transport was westward, down the axis of the geosyncline and that current directions remained essentially constant during the deposition of 13,000 feet of sediment. A turbidity flow mechanism dominated during sand transport and fallout, although existing oceanic currents may have aided sand distribution. In the Arkoma basin, which adjoins the Ouachita geosyncline on the north, sediment transport was southward across the basin as evidenced by paleocurrent readings on ripple marks and cross bedding. At the south margin of the basin, in a zone 6 to 8 miles wide, paleocurrents were deflected abruptly westward to parallel those of the geosyncline. Facies relations, sedimentary petrology, and paleocurrent studies all indicate that the Ouachita geosyncline derived its sediments from marginal sources. In Oklahoma a substantial amount of the Stanley was derived from the south margin of the geosyncline, as shown by paleocurrent and petrographic studies. Petrographic studies indicate that a significant amount of the Jackfork Sandstone of Arkansas also was derived from the south. Some of the sand for the turbidites was derived from the craton to the north, transported southward across the Eastern Interior basin, and debouched into the Ouachita geosyncline in eastern Arkansas or western Mississippi. Turbidity flows transported the sand down the axis of the trough to the west where it intermingled with sediments from southern sources. > The sole marks of each major thrust plate are parallel to those of adjacent thrust plates, indicating that there was very little rotation of the thrust plates as they moved northward. It seems likely that the Arkoma basin-Ouachita geosyncline transition facies now lies buried beneath the outer edge of the Choctaw thrust plate.

Nature and Recognition of Limestone Turbidites, Marathon Region, Texas: ABSTRACT

The Dimple Limestone (Pennsylvanian) of the Marathon region represents a period of carbonate deposition which interrupted the deposition of a thick terrigenous flysch section in the Ouachita geosyncline. It consists from north to south of laterally adjacent shelf, slope, and basin facies. The shelf facies is characterized by cross-bedded oolith carbonate grainstone. The slope and basin facies consist of sequences of distinctive limestone turbidite. Paleocurrent analysis indicates the existence of a uniform paleoslope dipping southward, with no apparent slope break. Slope-facies turbidites (proximal turbidites) display a wide variety of internal characteristics. They may be graded, reverse graded, or non-graded in their lower parts, but grade abruptly in their upper parts. Basal parts commonly are conglomeratic, and carbonate-mudstone upper parts commonly are absent. Floating pebbles are common, and 3-foot-thick cross-bedded units have been observed. Small-scale cross-bedding is rare, and large-scale convolutions are abundant. Associated rocks are subaqueous slump conglomerate, spicular carbonate mudstone, and black spicular marl. This facies is 5 miles wide. Basin-facies turbidites (distal turbidites) are nearly always graded. Pebbles are scarce, and the coarsest sizes are sand or silt. Carbonate mudstone beds are well developed, and were deposited from turbidity currents because (1) thick mudstone beds overlie thick graded beds, and (2) the normal pelagic sediment is radiolarian-bearing marl. Small-scale cross-bedding is abundant and convolutions are common. Thick beds are commonly massive, becoming laminated and cross-bedded on a small scale upward. Thin beds are commonly laminated. Associated rocks are black radiolarian-bearing marl and spicular chert. Information gained from the Dimple Limestone was applied to lower Paleozoic rocks in the region, and revealed slope-and-basin-facies limestone turbidites in the Ft. Pean Formation and Maravillas Chert (Ordovician). It appears that some geosynclinal limestone turbidite is the product of major tectonism, and is introduced from the cratonic side. End_of_Article - Last_Page 483------------

Devonian-Mississippian Stratigraphy of Western Mid-Continent Area: ABSTRACT

Stratigraphic relationships of Devonian and Mississippian rocks in the western Mid-Continent region provide overwhelming evidence that mid-Paleozoic seas were transgressive and widespread throughout the area. The present distribution of these marine strata is largely the result of erosion along the Transcontinental arch and adjacent uplifts. Strata of Early Devonian age are known only in areas that were included in the Cordilleran, Ouachita, and Arbuckle geosynclines and the Tobosa, Illinois, and North Kansas basins. These rocks were deposited on a highly eroded terrane. In medial Devonian time the seas transgressed southward from Alberta, Canada, into the North Dakota part of the Williston basin; westward and southward from Iowa into the Kansas-Nebraska part of the North Kansas basin; and eastward from the Cordilleran geosyncline into western Colorado. Middle Devonian strata are absent from Oklahoma and the Transcontinental arch, but are present farther south in the Tobosa basin and the Ouachita geosyncline. If Middle Devonian strata were deposited in Oklahoma and South Dakota, they have been completely removed by pre-La e Devonian erosion which was widespread throughout the eastern half of the western Mid-Continent. Late Devonian rocks indicate a resumption of transgression, and they may have covered the entire region although present distribution of these rocks is the result of Early Mississippian and later periods of emergence along the Transcontinental and associated arches. Mississippian rocks are conveniently divided into Lower Mississippian Series (Waverlyan) which comprises the Kinderhookian Stage and the Osagian Stage, and the Upper Mississippian Series (Tennesseean) which is made up of the Meramecian and Chesteran strata. The dark-shale units of western Montana and northwestern Wyoming, the shale and siltstone units of the Williston basin, and the black shale units which surround the Ozark uplift seemingly contain the Devonian-Mississippian systemic boundary. Elsewhere, basal Mississippian clastic and carbonate rocks are found unconformably not only on Devonian but also on Silurian, Ordovician, Cambrian, and Precambrian rocks. Local facies changes of Mississippian rocks in the area of the Ozark uplift indicate that this region was emergent during th early part of Mississippian time. Mississippian rocks of the western Mid-Continent are dominantly marine, shallow-water deposits. Seaways must have been very extensive in Mississippian time and the Kinderhookian transgressing sea probably came from both the north and south and was deposited on a peneplain-like surface. In western Kansas, late Kinderhookian rocks overlie Early and medial Ordovician rocks and are overlain by late Osagian rocks. Conodonts recovered from cores of western Kansas indicate that Upper Devonian rocks once were present west of the Central Kansas uplift. Mississippian rocks probably covered the entire Mid-Continent and Rocky Mountain regions but were most thin over the Transcontinental arch and the incipient Ancestral Rockies. Locally in south-central Kansas, rocks of Osagian age rest directly on pre-Mississippian rocks and show either (a) that the sea covered territory not inundated by the first transgression, or (b) that rocks of the Kinderhookian Stage were entirely eroded before deposition of Osagian rocks. Some workers believe that a major unconformity is present between Lower and Upper Mississippian rocks on the basis of megafossil studies recovered from outcrops peripheral to the Ozark uplift. However, study of microfossils from these rocks fails to support this hypothesis. Late Meramecian carbonate rocks in western Kansas End_Page 1901------------------------------ contain abundant quartzose clastics thought to be derived from the Central Kansas uplift and Las Animas arch. In the Williston basin, Mississippian rocks are dominantly carbonates but in Late Mississippian time thick evaporites were deposited. Late Mississippian or Chesteran deposits are not common in the Rocky Mountain region and may have been removed by pre-Pennsylvanian erosion. Chesteran time was characterized by advance and retreat of the shallow seas in the Mid-Continent area and strata reflect rhythmic displacement of the strandlines into basinal areas. The Chesteran seas were less widespread than Meramecian seas. Present distribution of Mississippian rocks outlines Late Mississippian-Early Pennsylvanian tectonic features, but the dominant tectonic feature throughout Devonian-Mississippian time was the Transcontinental arch. End_of_Article - Last_Page 1902------------

Dispersal and Petrology of Sandstones of Stanley-Jackfork Boundary, Ouachita Fold Belt, Arkansas and Oklahoma

Sandstones of the uppermost Stanley and lowermost Jackfork Groups (both flysch deposits) include arkose, subarkose, subgraywacke, feldspathic subgraywacke, and orthoquartzite (Folk, 1954, sandstone classification). Regional study of the uppermost part of the Stanley Group (Moyers Formation) shows that arkose and subarkose occur in the western Ouachita Mountains, and arkose and feldspathic subgraywacke occur in the south-central Ouachitas. Orthoquartzites occur only in the northeastern part of the fold belt. In the lowermost part of the Jackfork Group (Wildhorse Mountain Formation), subarkose occurs in the southern part of the Ouachita geosyncline, whereas subgraywacke is limited to the northwestern part of the geosyncline. Orthoquartzite occurs throughout the rest of the uachita fold belt. A linear regression analysis comparing feldspar content with both clay matrix and authigenic mica indicated that the amount of diagenetic matrix is negligible. Most of the authigenic mica appears to be recrystallized primary matrix. Geographic distribution of sandstone classes suggests that the Moyers Formation was derived from two sources. Quartzose material was derived from a northern source (Ozarks) and feldspathic material was derived from a southern source. Detritus was transported laterally into the Ouachita geosyncline. The sandstone of the Wildhorse Mountain Formation was derived from the same two sources and from a third source east of the present outcrop belt. Quartzose sandstone appears to have been deposited by a combination of lateral supply from the Ozarks and Illinois basin and subsequent redistribution by axial currents. Lateral supply was accomplished by turbidity currents, sand flow, and submarine slumping. Directional mapping of flute casts by others indicated that deposition of sand in the Ouachita geosyncline was accomplished by axially oriented currents rather than by downslope currents. The assumption that axially oriented flute casts were formed by the same turbidity currents that transported sand from the geosynclinal margin is inconsistent with interpretations based on mineralogical data. Oceanographic studies show that deep-water currents, flowing parallel with topographic strike, flow at velocities sufficiently high to erode silt and clay. Similar ocean currents probably reworked the marginally supplied sands and resedimented them in an axial direction in the Ouachita geosyncline. The axial orientation of some sole marks in ancient flysch deposits possibly records the direction of flow of ancient resedimenting ocean currents, whereas the regional distribution of sandstone types possibly indicates lateral supplying of sand by gravity-induced turbidity currents, submarine slumps, or sand flow. An oceanographic model consisting of sand emplacement by gravity-induced processes and later resedimentation by axially oriented ocean currents is offered as the most plausible mechanism to resolve anomalous provenance interpretations based on mineralogical and directional data.

Geosynclinal Filling: Some Stratigraphic-Structural Relationships: ABSTRACT

A geosyncline does not develop by mere crustal sag but rather by movement along faults. Contemporaneous faults are known to have been active during development of the large Ouachita and Gulf Coast geosynclines and development of the small but active Los Angeles, Hanna, and Ardmore basins, which are tectonically similar. The sedimentary fill of tectonically similar geosynclines, however, may be quite different. The Los Angeles Basin along the continental margin received thick turbidite deposits before it was filled to shelf depths. During its rapid subsidence, the Hanna Basin within the landlocked western interior filled with alluvial deposits. The Ardmore Basin during the late Paleozoic received shallow marine and coastal (paralic) sediments. Disharmonic folds involving the thick, ductile Springer-Goddard Shale indicate the influence of rock type in forming local structural features. While the Springer Shale was being deposited in the Ardmore Basin, turbidites were being deposited along the length of the Ouachita geosyncline. After water depths shoaled, shallow marine beds of the Atokan were deposited. The over-all regressive sequence of the Tertiary in the Gulf Coast geosyncline has resulted in paralic sediments overlying ductile, offshore, and deep-water shales. This relation may have been the cause of structures formed independently of salt tectonics. Such features are thought to be analogous to those failures recognized causing failures in foundation engineering and to the Recent mudlumps of the Mississippi River. End_of_Article - Last_Page 358------------

Paleocurrent Study of the Tesnus Formation, Marathon Basin, Texas

ABSTRACT The Tesnus Formation of west Texas is discussed as an integral part of the Ouachita geosyncline. It is probably equivalent in age to at least part of the Stanley-Jackfork sequence of the Ouachita Mountains of Oklahoma. The general characteristics of the formation indicate that the Tesnus sediments were deposited as a flysch facies in the subsiding Ouachita geosyncline. An environment of quiet water mud deposition was frequently interrupted by the rapid introduction of sand, possibly carried by turbidity currents. The paleocurrent study, in which sedimentary current structures on the undersides of the sandstone layers were used, indicates that the source was to the southeast.

Pennsylvanian and Permian Regional Stratigraphy of Western Mid-Continent: ABSTRACT

Pre-Des Moines (pre- Thirteen-Finger limestone), Des Moines, Missouri, and Douglas sediments were deposited by a transgressive Pennsylvanian sea which originated in the Ouachita geosyncline and invaded the western Mid-Continent through the Ardmore and Anadarko basins. Successively younger Pennsylvanian beds overlapped older from the Anadarko basin onto the Central Kansas uplift, and unconformably onlapped pre-Pennsylvanian Paleozoic rocks. During this transgressive phase the Anadarko basin expanded areally as shown by the shelfward migration of (1) the hinge lines and (2) the shelf-carbonate to basin-shale facies changes. When the Anadarko basin expanded to merge with the McAlester basin on the east, blanket sandstones in the latter moved progressively westward into the Anadarko basin. During Shawnee, Wabaunsee, Council Grove-Admire, and Chase deposition the sea began to withdraw from the western Mid-Continent and move toward the West Texas region through the Dalhart and Palo Duro basins. The Anadarko basin diminished in areal extent as hinge lines moved basinward, and became an embayment off the thicker deposits on the southwest. Shelf-carbonate to basin-shale facies changes moved progressively basinward, and blanket sandstones became successively smaller in areal extent. Permian red shales and sandstones shed by the Apishapa and Front Range uplifts were deposited in the western Mid-Continent in the wake of the retreating sea. End_of_Article - Last_Page 130------------

Cyclothems and Larger Sedimentary Cycles of the Pennsylvanian

Uncertainty regarding the relations of cyclothems, as recognized in Illinois, and megacyclothems, that are typically developed in eastern Kansas, has obscured the correlation of Pennsylvanian strata east and west of the Mississippi River and the interpretation of physical events that influenced sedimentation during the Pennyslvanian period. Lithologic analysis of the Kansas megacyclothem indicates that it is not equivalent to an Illinois cyclothem, as some have believed, but is composed of three or more incompletely developed simple cyclothems. A large sedimentary cycle recognized in Illinois, consisting of three or more different types of cyclothems, appears to be a differently developed, but otherwise comparable, megacyclothem. The suggestion is made that megacyclothems owe their existence to movements in the Ouachita geosyncline, which superimposed a large cycle on the small one responsible for the development of cyclothems. A still larger cycle, termed a hypercyclothem, is recognizable in eastern Kansas but is not explained.

Geologic Interpretation of Argillaceous Sediments: Part II. Clay Petrology of Upper Mississippian-Lower Pennsylvanian Sediments of Central United States

X-ray diffraction analysis of Upper Mississippian-Lower Pennsylvanian shales from the Ardmore and Anadarko basins indicates that the Meramecian Caney shales are characterized by the abundance of illite and the scarcity of chlorite and kaolinite, the Chester shales by the presence of illite and montmorillonite, the Springer shales by the presence of montmorillonite and the absence of illite, the Lower Pennsylvanian Morrow shales by an abundant illite content, and the Atoka shales by the relative abundance of mixed-layer clay. The Chester and Springer formations, which can be divided into three geographic provinces, are overlain by a 200±-foot mixed interval which consists of a mechanical mixture of the Morrow and underlying formation clays. The type of reworked Springer clay in the mixed interval can be used to identify the geographic province of the underlying Springer section. Both the Morrow and Atoka shales contain distinctive interfingering beds of reworked Springer shales which appear to be restricted to wells situated near the downthrown sides of faults. In the Ouachita geosyncline the Upper Mississippian Stanley shale is characterized by the presence of illite, chlorite, and feldspar, the Lower Pennsylvanian Jackfork and Johns Valley shales by the presence of mixed-layer clay and the relative scarcity of kaolinite and chlorite. Near the northern margin of the Ouachita area the lower Stanley shale is similar in composition to the Caney and Springer shales, indicating a transition between the two basins. The Stanley illite-chlorite shales and high-rank graywacke sandstones were deposited in a rapidly sinking eugeosyncline. The sediments were derived from a metamorphic-acid igneous complex on the south. The closely related Chester and Springer montmorillonitic shales and orthoquartzite-quartzose graywacke sandstones were deposited in a rapidly sinking intracratonic basin. They were probably derived from a broad, low-lying sedimentary-volcanic source north and south of the basin. The southern source area may have extended toward the east and partly separated the two depositional areas. The Pennsylvanian (Morrow) was ushered in by a major uplift and metamorphism in the southern part of the Ouachita eugeosyncline, and minor faulting along the southern flank of the Anadarko and Ardmore basins. The micaceous Jackfork shales (Ouachita basin) and orthoquartzite sandstones were derived from this Ouachita uplift. The micaceous Morrow shales (Ardmore and Anadarko basins) were derived in part from the Ouachita area and in part from the periodically uplifted montmorillonitic sediments along the south flank of the basins. At the beginning of Atokan time there was increased uplift along the south flank of the basins (the Wichita Mountains and Criner Hills) and as a result the Atokan shales are more montmorillonitic than the Morrow shales, and the sandstones are typical low-rank raywackes. Regionally the clay mineral suites in the Arkansas and Illinois basins and in the north Texas area can be related to those in Oklahoma. End_Page 272------------------------------