Beach Sandstones Research Articles

Stratigraphic Analysis of Upper Permian and Lower Triassic Strata in Southern Utah

Permian sedimentation in southwestern Utah was influenced by three principal depositional areas--the Oquirrh basin in north-central Utah, the Cordilleran geosyncline in eastern Nevada, and the Quemado-Cuchillo basin on the northern shelf of the Sonoran geosyncline in east-central Arizona and west-central New Mexico. Throughout Permian time, marine sediments and well-developed beach and continental eolian sandstone equivalents were deposited within these basins and on the surrounding shelves. Each of the three depositional sites appears to have exerted influence on sedimentation during a discrete period of geologic time. Thus, while one basin was the site of sedimentation, the other two basins were relatively quiescent. Remarkably similar beach and continental sandstone deposits are related to each basin, and all these sandstones extend to a common depositional area in southwest Utah where they are interlayered. Vertical juxtaposition or interlayering of littoral and beach sandstone facies that are related to three differing sedimentational basins has been responsible for most of the problems invo ving Permian nomenclature and correlation in the Colorado Plateau province. Stratigraphic analyses show that each continental sandstone facies has a basinal stratigraphic equivalent which consists primarily of interbedded carbonate with smaller amounts of sandstone and shale. The beach and basinal equivalents present are: Cedar Mesa Sandstone equivalent to Elephant Canyon carbonates; Organ Rock Shale equivalent to Meseta Blanca Sandstone and Yeso evaporites and carbonates; Coconino Sandstone, to upper De Chelly Sandstone; White Rim Sandstone (approximately upper 80 percent), to Toroweap Formation; and upper White Rim Sandstone, to lowermost (Gamma member) Kaibab Formation. Rock units underlying the Toroweap-White Rim Formations are younger toward the south. The Kaibab Formation is a stratigraphic continuation of the Franson Member of the Park City Formation in northern Utah and southwestern Wyoming and is inferred to be time-transgressive. The Permian-Triassic boundary is recorded by a pronounced unconformity in southwesternmost Utah. Northward, the break is less pronounced and is not recognizable in north-central Utah. Early Triassic sedimentation in southern Utah appears to record cyclic response to one major subsiding sedimentational area, the Cordilleran Triassic basin, apparently with characteristic onlap relations, and at least two and possibly three of the Early Triassic Moenkopi units are not present at the Moenkopi type section in northern Arizona. The southward continuation of the Woodside Formation from southwestern Wyoming to central Utah is now recognized. The Sinbad and Timpoweap Members of the Moenkopi Formation are shown to be the same stratigraphic unit. Subsurface control suggests that the Virgin Limestone Member extends into central Utah. Structurally, most of southern Utah appears to have been a slowly subsiding shelf throughout most of Permian and Early Triassic times.

Depositional Model--upper Cretaceous Gallup Beach Shoreline, Ship Rock Area, Northwestern New Mexico

To provide an example of ancient deposits across a sand-beach shoreline for comparison with both Recent and other ancient deposits, a cross-sectional model was constructed from surface exposures across the Upper Cretaceous Gallup shoreline in the Ship Rock area of northwestern New Mexico. Tile model shows lower Gallup regressive-beach sandstone overlain unconformably by upper Gallup transgressive offshore-bar sandstones. Landward, the beach sandstone interfingers with coal-swamp deposits or is truncated and overlain by dune standstone. Seaward, the beach sandstone grades through shoreface sandstone into a transition that gives way to offshore siltstone and mudstone. Offshore siltstone and mudstone overlie and in part grade laterally into offshore-bar sandstone, which has no contiguous landward equivalents and transgresses all beach and related facies. Within their particular stratigraphic frameworks, sedimentary structures, supported by lithologic and paleontologic data, identify both the beach and the offshore-bar sandstones as well as their related facies. Both the beaches and the offshore bars consist of imbricate patterns of parallel beds. Beds in the backshore beach consist of cross laminae that dip either in diverse directions or landward and that compose laminasets, which are swale fillings; cross laminae in the foreshore beach dip uniformly seaward at low angles. Beds of shoreface sandstone are either churned by burrowing organisms or composed of large-scale truncated wave-ripple laminae. in the transition between shoreface and offshore siltstone and mudstone, beds of mudstone interfinger with bells of sandstone and siltstone, which show small-scale truncated wave-ripple laminae and churned structure. Siltstone and mudstone beds alternate in offshore rocks, and the siltstones contain both current-ripple and truncated wave-ripple laminae, except where burrowing organisms have destroyed the laminae. Most beds of offshore-bar sandstone are churned, but some show high-angle cross laminae that dip parallel with the length of the bar and approximately parallel with the distant shoreline. Burrowing organisms have completely churned the muddy sandstone beds of the offshore-bar transition.

Genetic Units and Delta Prospecting: ABSTRACT

Deltas generally are formed at river mouths during stillstands of sea level under conditions of either cyclic transgression or regression. Consequently, they are rarely isolated phenomena, but are present in multiples in a predictable fashion. Reservoir facies consist of both continuous and discontinuous, bifurcating channel sandstones that thicken downward at the expense of the underlying prodelta clays. All the lithologic components of a deltaic complex are related to each other and are collectively referred to as one type of increment of (GIS). The GIS is a sequence of strata in which each lithologic component is genetically related to all the others. It is defined at the top by a time-lithologic marker bed (such as a thin limestone or bentonite), and at the base by either a time-lithologic marker bed, an unconformity, or a facies change from marine to nonmarine beds. It generally consists of the sum total of all marginal marine sediments deposited during one stillstand stage of a shoreline, or it may be a wedge of sediments deposited during a series of cyclic subsidences or emergences. An isopach map of a GIS clearly shows the bifurcating trends of the individual d stributaries and the shape of the delta, regardless of the variable lithology of the channel fills. A genetic sequence of strata (GSS) consists of two or more GIS's and, when isopached, clearly defines the shelf, hinge line, and less stable part of a depositional basin. An isopach map of the McAlester Formation of the Arkoma basin is a good example of a GSS. The oil-productive Booch Sandstone is a good example of a deltaic complex occurring within a GIS of this GSS. The upper Tonkawa, Endicott, and Red Fork Sandstones of the Anadarko basin are deltaic accumulations within different GIS's. A hypothetical model serves to establish the criteria for (1) recognizing successive stillstand positions of a shoreline, (2) predicting paleo-drainage courses, (3) predicting positions of a series of deltaic reservoirs, (4) locating isolated channel sandstone reservoirs, and (5) tracing related beach sandstone reservoirs. End_of_Article - Last_Page 152------------

Genetic Units in Delta Prospecting

Deltas generally are formed at river mouths during stillstands of sea level under conditions of cyclic transgression or regression. Consequently, they are rarely isolated phenomena, but form in multiples in a predictable fashion. Reservoir facies consist of continuous and discontinuous, bifurcating channel sandstones and delta-front sheet sandstones. The channel sandstones generally thicken downward at the expense of the underlying prodelta clays and may replace selected parts of the delta-front sheet sandstones. The lithologic components of a deltaic complex are interrelated and are referred to collectively as one type of Genetic Increment of Strata (GIS). The GIS is a vertical sequence of strata in which each lithologic component is related genetically to all the others. It is defined at the top by a time-lithologic marker bed (such as a thin limestone or bentonite) and at the base by either a time-lithologic marker bed, an unconformity, or a facies change from marine to nonmarine beds. It generally consists of the total of all marginal marine sediments deposited during one stillstand stage of a shoreline, or it may be a wedge of sediments deposited during a series of cyclic subsidences or emergences. An isopach map of a GIS clearly shows the bifurcating trends of the individual distributari s and the shape of the delta, regardless of the variable lithology of the channel fills. A Genetic Sequence of Strata (GSS) consists of two or more contiguous GIS's and, when isopached, clearly defines the shelf, hinge line, and less stable part of a depositional basin. An isopach map of the McAlester Formation of the Arkoma basin is a good example of a GSS. The oil-productive Booch sandstone is a good example of a deltaic complex occurring within a GIS of this GSS. The upper Tonkawa, Endicott, and Red Fork sandstones of the Anadarko basin are identified as deltaic accumulations within different GIS's. A hypothetical model serves as a basis for establishing the criteria for (1) recognizing successive stillstand positions of a shoreline, (2) predicting paleodrainage courses, (3) predicting positions of a series of deltaic reservoirs, (4) locating isolated channel sandstone reservoirs, and (5) tracing related beach sandstone reservoirs.

Un exemple de grès de plage (côte Ligure Italienne)

An example of beach sandstone (Ligurian coast, Italy) The authors indicate an easily observable example of beach sandstone. They suggest an interpretation for its formation in the contact zone between fresh phreatic and marine water. Out-cropping of such a sandstone is a clue to recent erosion.

Stratigraphic Analysis Through Determination of Depositional Environments: ABSTRACT

The Mesaverde Formation of the Western Interior Cretaceous seaway includes rock units representative of off-beach, beach, lagoon, swamp, and floodplain environments of deposition. Because of migration of the shoreline by transgression and regression, the sedimentary products of various environments are arranged vertically in the geologic record in the same succession as they occurred laterally at the time of deposition. The detailed distribution of the potential reservoir beach sandstone bodies in a regressive sequence follows different patterns, depending on variations in the relative rate of submergence during progradation. These variations are reflected in the character of the back-beach environment. A mainland beach-floodplain progradation, reflecting a low rate of su mergence, results in a tabular sheet of beach sandstone which intertongues only slightly with the overlying floodplain End_Page 2036------------------------------ rocks; a barrier island-lagoonal progradation, reflecting a high rate of submergence, comprises a series of discrete sandstone lenses arranged en echelon, each lens intercalating landward with lagoonal deposits and seaward with off-beach marine shale. During transgression, because of the step-like topography of a barrier island-lagoonal terrain, shoreline sandstone bodies are developed only discontinuously, giving rise to asymmetrical cycles. Because of the general paucity of organic remains in the Mesaverde, the determination of depositional environments commonly must be accomplished by the evaluation of stratification. Though there are no single stratification features peculiar to particular environments, sequences of stratification may be diagnostic. Stratification in rocks occurs in response to physical-depositional processes; the vertical sequence of stratification in a regressive suite of rocks reflects the lateral distribution of processes operative at the time of deposition. Beach stratification, from bottom to top, includes laminae deposited in the transition zone between off-beach shale and offshore beach sandstone, the submarine bar zone, the fore-shore beach, and the back-shore beach. A vertical sequence of lag on stratification may reflect deposition in a tidal delta, lagoon pond, tidal channel, wave flat, and salt marsh. The character of the stratification in the different sub-environments may be determined by study of modern environments and processes; the great variety of processes present within these modern environments yields perspective on the variety of stratification to be expected in the geologic record. End_of_Article - Last_Page 2037------------

Elwood Field: ABSTRACT

The Elwood field is located along the coast line, 10 miles west of Santa Barbara, California. Less than 500,000 barrels of heavy oil has been recovered from the Rincon Shale, almost 100 million barrels of 28°-36° A.P.I. oil from the Vaqueros Sandstone (a shallow-water transgressive beach sandstone), and more than 3 million barrels of 33°-38° A.P.I. oil from four zones of the Sespe Formation (non-marine sandstone with siltstone interbeds). Productive area is slightly more than 690 acres. Early offshore wells were drilled from piers and later wells were directionally drilled from the adjacent sea cliffs. Complex east-west-trending reverse and lateral-type faults parallel the Elwood anticlinal structure on the north and south. One minor cross-fault in the western productive area is not an effective barrier to oil movement. Naples offshore field, located 2 miles west on the Elwood trend, and La Goleta gas field, located 4 miles east on the Elwood trend, are characterized by geologic conditions similar to those in the Elwood field. End_of_Article - Last_Page 652------------

Correlation of Grain-Size Distribution and Mineralogy with Depositional Environment in the Dakota Formation (Cretaceous) of the San Juan Basin, New Mexico and Colorado: ABSTRACT

The depositional environment of units within the Dakota formation of the San Juan basin was determined by means of fossils, sedimentary structures, and facies relationships. Grain-size distribution, heavy-mineral content, and clay-mineral content were found to correlate well with the depositional environment in a manner similar to observations reported from modern sediments. Many depositional environments are represented in the Dakota formation, which grades from lenticular, non-marine sandstone and carbonaceous shale in the northwestern San Juan basin to regularly interstratified shale and very fine-grained sandstone in the southeastern San Juan basin. Dakota fluvial sandstones are fine-skewed and are generally poorly sorted. Dakota beach sandstones are coarse-skewed and well sorted, while Dakota offshore marine sandstones are fine-skewed and are generally moderately well sorted. The finer particles in Dakota offshore sandstones were winnowed from beaches and were deposited offshore. Dakota fluvial sandstones characteristically are fine-skewed. The finer particles in these fluvial sandstones were not winnowed and the competence of stream flow sets an upper limit to the size of particles transported. In a vertical series of samples from Dakota sandstones grading from nonmarine deposits below to marine deposits above, the degree of sorting increases upward into the lower part of the lowest marine sandstone (beach deposit) and gradually decreases in offshore sandstones above the beach sandstone. The change in skewness from coarse in the beach sandstone to fine in the fluvial and offshore marine sandstones is abrupt. Dakota non-marine shales contain much kaolinite with some illite. The amount of carbonaceous matter in the shales is inversely related to the amount of illite. Dakota marine shales contain much montmorillonite in addition to kaolinite and illite. Dakota sandstones derived from source areas north and west of the San Juan basin have a small, stable suite of heavy minerals in which zircon and tourmaline predominate. Most of these mineralogically simple sandstones are non-marine. Dakota marine sandstones, such as the Tres Hermanos and Twowells members, which were derived from source areas south of the San Juan basin, contain a suite of metamorphic minerals in addition to zircon and tourmaline. End_of_Article - Last_Page 540------------

Petrology of Some Pennsylvanian Sedimentary Rocks

ABSTRACT The middle Allegheny Kittanning Formation near Brookville, Pennsylvania is composed mainly of detrital rocks--sandstone, siltstone, and claystone, with minor volumes of coal, limestone, and ironstone. Detrital constituents are quartz (approximately 25%), micaceous metamorphic and sedimentary rock fragments, coarse micas and clays (about 70%), and miscellaneous silicates totalling about 5%. The average grain size is medium silt. Sandstones and coarse siltstones can be classified into four descriptive-genetic groups based on quartz content and color relative to grain size and on primary structure and fossil content. Alluvial channel sandstone and coarse siltstone are characterized by relatively low quartz content, intermediate relative color, well-developed tabular-lenticular stratification, and a large stem flora. In contrast, beach sandstone and siltstone are relatively quartz rich and, excepting for possible worm burrows, are without distinctive fossils. Coarse grained lacustrine deposits have properties intermediate between those of channels and beaches. Lagoonal sandstone and siltstone are distinctive because of their relatively dark color and low quartz content. They also la k stratification and contain a marine fauna. Varieties of finer grained sediments are distinguished by relative color and by structure and fossil content. Fine grained alluvial sediments are relatively light colored, generally contain roots or upright stems and often lack stratification. Offshore lacustrine, brackish, and marine deposits are differentiated mainly by fossil content. Both fine and coarse grained sediments of similar genetic type occur in stratigraphic groups of considerable areal extent and reflect two times of marine transgression interrupted by an episode of fluvial-lacustrine deposition.

Mesaverde Group in Adjoining Areas of Utah, Colorado, and Wyoming: ABSTRACT

The mixed marine and nonmarine Mesaverde group (Late Cretaceous) overlies and intertongues with the marine Mancos shale or its equivalents and underlies and intertongues with the marine Lewis shale or underlies continental rocks of latest Cretaceous or Paleocene age. The area studied is approximately 200 miles square on both sides of the Wyoming and Utah-Colorado state Formations and members in 7 smaller geographic subdivisions are described and related in terms of Lee's (1915) genetic units to a standard four-fold section in the Rock Springs uplift consisting from oldest to youngest of the Blair, Rock Springs, Ericson, and Almond formations. Data from 14 measured surface sections and more than 120 wells were used to make isopach maps of individual formations, members and tongues. These maps show that basins and relative arches of Late Cretaceous time correspond fairly well with those of Tertiary time and that the maximum thickness of a genetic unit is at the zone of transition from continental to marine sedimentation. Numerous minor transgressions and regressions of the sea are imposed on a general eastward regression during Mesaverde time followed by a major transgression during Lewis time and a complete withdrawal of the sea after Lewis time. There are numerous cyclothems consisting of gray marine shale, tan marine siltstone and sandstone, gray and white beach sandstone, coal, brown carbonaceous shale, and gray to brown carbonaceous siltstone. Both transgressive and regressive deposits are present. Two probable controls of intertonguing are recognized: (1) intermittent delivery of sand and mud by streams along a subsiding delta front and reworking by marine currents; (2) several rather rapid changes of sealevel or landlevel, either tectonic or eustatic. Most of the sediments were derived from areas west of the Wasatch line. Toward the close of Mesaverde deposition, local uplifts in the site of the present Uinta Mountains and possibly the Wind River Mountain provided a source for sediments. Short-ranging fossils are scarce in the Mesaverde group in this area. The marine shale tongues generally contain long-ranging arenaceous foraminifera and the marine sandstones contain Ostrea sp., Inoceramus sp., Halymenites major and worm tubes; the faunas are useful as indicators of paleoenvironments, but are not useful for stratigraphic correlations. No new formation names are proposed. Several unnamed sequences should be mapped and traced laterally before they are named. The Lazeart sandstone is raised from member to formational rank. The Rimrock sandstone and the Asphalt Ridge sandstone of Walton (1944) are considered members of the Iles formation. End_of_Article - Last_Page 954------------

Dakota Group of Colorado Plateau

Basal Cretaceous deposits of the Colorado Plateau can be subdivided into two formations on the basis of carbonaceous content. The lower non-carbonaceous unit, the Cedar Mountain formation, consists of mudstones and persistent conglomeratic sandstones which were deposited in an inland floodplain environment. The upper carbonaceous unit, the Naturita formation, consists of carbonaceous mudstone, coal, persistent conglomeratic sandstones, and beach sandstones deposited on or adjacent to the shore of the Mancos sea. Naturita deposits can be traced landward into Cedar Mountain deposits, indicating that they are facies of a larger unit, the Dakota group. Advancing Cretaceous seas reached the eastern edge of the Plateau in late Albian time but did not inundate the entire Plateau until late Greenhorn or early Carlile time. The westward advance of the sea was a halting one. Sharp pulses of basinal subsidence, accompanied by uplift in the source area west of the Plateau, resulted in rapid westward transgressions of the sea. Deposition, essentially confined to periods of quiet following the transgressions, caused some regression of the sea but transgressions exceeded the regressions and resulted in a slow westward advance of the sea. Many pulses of subsidence occurred but five major ones, which were accompanied by uplift in the source area, are reflected in the five widespread orogenic sandstones present in these deposits.

Geology of Ulupau Head, Oahu

Ulupau Head is a secondary tuff crater forming the eastern salient of Mokapu Peninsula, northeast coast of Oahu, Hawaii. Subsequent to its building from an offshore, submarine vent, the crater was deeply eroded by wave action on the north and east sides, the rim being largely destroyed on the east, and the sea entering the bowl. Later, at a stand of the sea at least 45 feet above the present stand, a bed of oyster-bearing limestone and an overlying calcareous beach sandstone were deposited on steeply sloping rock surfaces inside the crater. Unconformable on these beds is a thick series of alluvial, tuffaceous silts, and in one sector a remarkable giant breccia, carrying 30-foot blocks of tuff and probably due to an enormous rock fall from an oversteepened marine cliff. At this time the sea stood at least as low as at present. Later reef formations and accompanying beach conglomerates indicate two more stands of the sea, the first at 25 feet and the second at about 12 feet above the present. Incorporated in the reef limestone of the northwest shore are great blocks of tuff let down by marine erosion from the rock-fall breccia and forming a remarkable reef breccia. This in turn, subject to attack by water-level weathering on the tuff blocks and solution benching on the reef limestone matrix, furnishes a striking example of the contrasted features of marine benches developed by processes peculiar to the two types of rock.