Sandstone Depositional Environments Research Articles

The Numidian Sandstones in northern Morocco: Evidence for early Burdigalian autochthonous deposition on top of the Tanger Unit

The Numidian Sandstones are widespread throughout the western Mediterranean, from Spain and North Africa to southern Italy. They consist of intercalations of thick ultra-mature sandstones within brownish shale deposits. Crucial issues about the Numidian Sandstones are still under debate, such as their pertinence to an undisputed paleogeographic domain and their age. In addition, in the Moroccan Rif, detailed sedimentological studies are still lacking, preventing the understanding of the main features of the sedimentary basin in which the Numidian Sandstones were deposited. This paper aims to reconstruct the Numidian Sandstone depositional environment via a detailed sedimentological study and provides new time constraints through quantitative analyses of calcareous nannofossil assemblages. The Numidian Sandstone sedimentary features suggest a depositional environment located in the transition between a lower muddy slope and a deeper basin plain. Quartz-rich sandy turbidites supplied sediments to this basin during a tectono-sedimentary event lasting ca. 1 Myr in the early Burdigalian. A key section from the Tanger Unit shows the Numidian Sandstones in stratigraphic continuity with the pre-Numidian deposits of the External Tanger Unit (Intrarif sub-domain). This evidence allows us to reject the notion of the Numidian Sandstones as a nappe, detached at their base from the pre-Oligocene deposits of the more internal units of the Flysch Basin. The new biostratigraphic analyses performed on the Numidian Sandstones from northern Morocco mostly correlate with the depositional age of the Numidian Sandstones outcropping in the rest of the Maghrebian Chain. The Numidian sand event, which affected the SW sector of the Mediterranean Basin from the Betics to the southern Apennines, was a unique and extensive event that was possibly triggered by the interplay among the uplift of the Atlas Chain, the sea-level drop at 20.4 Ma, and the establishment of a humid climate in North Africa at the beginning of the Miocene.

Latest Permian (Changhsingian) to Early Triassic (Induan-Olenekian) of the Mt Goodwin Sub-group at Blacktip gas field, southeastern Bonaparte Basin, Australia

Gas was discovered in intra-Mt Goodwin Sub-group sandstones (Ascalon Formation) of the southeastern Bonaparte Basin in Blacktip–1 in 2001 from a zone characterised by a discrete seismic amplitude anomaly. This integrated study uses wireline logs, cores, cuttings, palynology, micropaleontology and geochemical analyses to determine the depositional environment of the Mt Goodwin Sub-group reservoirs and the source rock potential of this large, latest Permian (Changhsingian) to Early Triassic (Induan Olenekian) section of the Bonaparte Basin in northern Australia. Specific outcomes include a better understanding of the Early Triassic reservoir sandstone depositional environment and recognition of marker horizons on electric logs and seismic profiles, resulting in a more consistent regional interpretive framework for the uppermost Permian (Changhsingian) and Early Triassic (Induan Olenekian), in the Bonaparte Basin.

Sandstone depositional environments of the Upper Permian Champenay Formation, Champenay Basin, northeastern France

The Upper Permian Champenay Formation was deposited in a series of continental basins in northeastern France. Within the lower part of this formation, there is a sandstone of controversial origin. In the Champenay Basin, this sandstone of the Champenay Formation is exposed in three quarries between the towns of Champenay and Belval. In these quarries the sandstone is composed of deposits from deltaic, lacustrine, beach, alluvial, and eolian environments. Interpretation of these deposits suggests that the Champenay Basin was occupied by a lake, and that deltaic sediments prograded into this lake from the southeast. Relative changes in lake level resulted in the development of bounding surfaces among the deltaic sediments. Debris flows, ephemeral sheet flows, beach deposits, and eolian dunes were also present along the southern margin of this lake. The eolian dunes were crescentic in shape and migrated to the northwest. Sediment entered the southern margin of the Champenay Basin and was then redistributed and reworked by deltaic, lacustrine, beach, and eolian processes.

Sandstone depositional environments edited by P. A. Scholle and D. Spearing, American Association of Petroleum Geologists, 1982. No. of pages: 410. Price: $42.00

Sandstone depositional environments edited by P. A. Scholle and D. Spearing, American Association of Petroleum Geologists, 1982. No. of pages: 410. Price: $42.00

Regional Trends in Porosity and Permeability of J Sandstone in Denver Basin--Controls of Burial History: ABSTRACT

The Lower Cretaceous J sandstone is the principal reservoir for oil and gas in the Denver basin of Colorado, Wyoming, and Nebraska. Net pay of the J sandstone depends strongly on sandstone depositional environments, but other important aspects of reservoir quality reflect the burial history. Most notable of these are porosity, permeability, depth, and degree of thermal maturation (as indicated by vitrinite reflectance). An understanding of the regional interrelationships between these variables is important in predicting reservoir quality and in estimating undiscovered petroleum resources in the Denver basin. Statistical treatment of the core analysis and well-log data from 134 widespread boreholes across the basin, for which the U.S. Geological Survey has core, reveal the following. (1) Thermal maturity increases exponentially with depth, indicating increased temperature with burial. (2) Porosity decreases linearly with increasing Ro and depth. The presence of authigenic clays and carbonate cements are important to porosity reduction. In many examples across the basin, however, quartz pressure solution and precipitation processes are the main causes of porosity reduction, and these phenomena may be temperature-limited. (3) Permeability decreases exponentially with increasing depth. The permeability data exhibit more scatter than porosity, indicating a less direct relationship t depth and reflecting the effects of both porosity loss and increased surface area of the pore network. Authigenic clays, especially ordered illite-smectite, control the specific surface area of the pore network in the J sandstone. End_of_Article - Last_Page 851------------

Uranium Distribution and Sandstone Depositional Environments--Oligocene and Upper Cretaceous Sediments, Cheyenne Basin, Colorado: ABSTRACT

Wyoming-type roll-front uranium deposits occur in the Upper Cretaceous Laramie and Fox Hills sandstones in the Cheyenne basin of northeastern Colorado. The location, geometry, and trend of specific depositional environments of the Oligocene White River and the Upper Cretaceous Laramie and Fox Hills formations are important factors that control the distribution of uranium in these sandstones. The Fox Hills Sandstone consists of up to 450 ft (140 m) of nearshore marine wave-dominated delta and barrier island-tidal channel sandstones which overlie offshore deposits of the Pierre Shale and which are overlain by delta-plain and fluvial deposits of the Laramie Formation. Uranium, which probably originated from volcanic ash in the White River Formation, was transported by groundwater through the fluvial-channel deposits of the White River into the sandstones of the Laramie and Fox Hills formations where it was precipitated. Two favorable depositional settings for uranium mineralization in the Fox Hills Sandstone are: (1) the landward side of barrier-island deposits where barrier sandstones thin and interfinger with back-barrier organic mudstones, and (2) the intersection of barrier-island and tidal channel sandstones. In both settings, sandstones were probably reduced during early burial by diagenesis of contained and adjacent organic matter. The change in permeability trends between the depositional strike-oriented barrier sandstones and the dip-oriented tidal-channel sandstones provided sites for dispersed groundwater flow and, as demonstrated in similar settings in other depositional systems, sites for uranium mineralization. End_of_Article - Last_Page 512------------

Validity of Use of Spontaneous Potential Curve Shape in Interpretation of Sandstone Depositional Environments: ABSTRACT

The shape of spontaneous potential curves is frequently used in the interpretation of sandstone depositional environments. The cylinder-, funnel-, and bell-shaped SP profiles are among the most frequently employed. However, the validity of this commonplace practice has never been thoroughly established. Theoretical and experimental work and actual field examples suggest that the trend of the SP deflection does not display a direct relationship with the trend of variables known to be controlled by the sandstone paleoenvironment. The trend of quartz grain size shows a low linear correlation with the trend of SP deflection. The trend of clay content shows a higher correlation, but changes in clay type and cation exchange capacity can have more impact on the SP than the simple volume of clay. Field examples from the Upper Cretaceous and Tertiary of the Gulf Coast show that hydrocarbons, local variations in the mud filtrate salinity, and regional differences in formation water salinity can greatly alter the shape of the SP curve. This can result in erroneous interpretations of sandstone origin. Curve shapes derived from the microresistivity measurements of the dipmeter tool are an alternative to those of SP curves. The greater sensitivity of the dipmeter tool, its immunity to the problems of hydrocarbons and Rmf/Rw contrasts, and the relationship of microresistivity to primary rock properties are factors favoring the use of microresistivity curve shapes for the interpretation of sandstone depositional environments from subsurface data. End_of_Article - Last_Page 1220------------

Grain Size Vertical Progressions as an Exploration Tool: ABSTRACT

Previous studies of grain size as an indicator of sandstone depositional environments have had mixed results; for that reason, the method is seldom End_Page 448------------------------------ if ever used as an exploration tool. The problem with these previous studies is that they concentrate on grain-size parameters for individual samples, and fail to recognize that various depositional environments are characterized by a number of discrete facies, each with its own characteristic sedimentary structures and grain-size populations. For that reason, vertical progressions in grain-size data are far more diagnostic of depositional environment than are scatter diagrams in which one grain-size parameter is plotted against another. Grain-size progressions for ancient sequences of the Upper Cretaceous Point Lookout formation and Eocene Queen City Formation demonstrate the value of the technique. The data show that distinctions can be made between fluvial, estuarine/tidal distributary, flood-tidal delta, foreshore, and shoreface sandstones. More importantly, our method relies on analysis of samples collected at random intervals (generally 2 ft or .6 m), so that it is applicable where sidewall cores are available. Diagenetic complications (other than those resulting from silica cementation) do not appear to threaten the sensitivity of the method. Using automated settling analysis, these data are obtained rapidly and can aid in subsurface correlation as well as determining the depositional environments of sandstones End_of_Article - Last_Page 449------------

Validity of Spontaneous-Potential Curve Shape for Interpretation of Sandstone Depositional Environments: ABSTRACT

Many explorationists employ the spontaneous-potential (SP) curve shape as an aid in interpretation of sandstone depositional environments and prediction of subsurface sand-body occurrence. The bell, cylinder, and funnel-shaped SP profiles are among the most widely used. The basic assumption of users of these curve shapes is that decreasing deflection of the SP curve from the baseline is due to decreasing quartz grain size and/or increasing clay content in a reservoir sandstone. However, theoretical, experimental, and actual field data indicate that quartz grain size bears no relation to the amount of SP deflection. Clay content does show a relation, but is often overshadowed by a number of variables which affect SP. Hydrocarbons can also influence SP, often yielding a false bell profile. In addition, borehole or formation-pressure differentials, variations in mud-filtrate resistivity, and regional differences in formation-water salinity can greatly alter the SP curve shape. Bed thickness, especially when less than 3 ft (1 m), also exerts some control over the SP response. Field examples in which these factors influence SP in Gulf Coast sandstones demonstrate that the SP curve shape is often misleading. Paleoenvironmental reconstructions and predictions of subsurface sand-body occurrence based on such shapes would therefore be in error. Curve shapes derived from the micro-resistivity tool (expanded dipmeter curve) are suggested as alternatives to SP curve shapes. Unlike the SP, the micro-resistivity tool is immune to the effects of hydrocarbons, variations in mud-filtrate resistivity and formation-water salinity, pressure differentials, and bed thickness. End_of_Article - Last_Page 529------------

Recognition of Sandstone Depositional Environment: A Grain-Shape Approach, With Example from North Padre Island: ABSTRACT

The shapes of 8,000 fine quartz sand grains from Malaquite Beach, North Padre Island, were analyzed with the Fourier shape technique. It was found with this technique that dune sands can be differentiated easily from beach sands on the basis of both their gross and fine (roundness) shape characteristics. The analysis of samples from transects across the beach and dunes also reveals a high degree of grain-shape variation within these environments. This variation is due to the effects of hydrodynamic and aerodynamic sorting by swash and wind currents respectively. The Fourier technique provides a rapid and objective manner to discriminate between beach and dune sands, and can be applied to ancient as well as modern sands with equal facility. End_of_Article - Last_Page 1468------------

Pictured Cliffs Sandstone--Upper Cretaceous Distributary-Channel, Delta-Front, and Beach-Bar Deposits, Southwestern San Juan Basin, New Mexico: ABSTRACT

The Upper Cretaceous Pictured Cliffs Sandstone in the Bisti-Burnham area in southwestern San Juan basin, New Mexico, contains distributary-channel, delta-front, and beach-bar deposits. The distributary-channel deposit is a basally erosional, festooned, convoluted, and rippled sandstone. The delta-front deposits include distributary-mouth-bar sandstone, distal-bar sandstone, siltstone, shale, and intervening contorted sandstone. The distributary-mouth-bar sandstone is subparallel laminated, rippled, and festooned. The distal-bar sandstone is subparallel laminated and rippled. The intermediate contorted sandstone contains fold and ball-and-pillow structures. The distributary-channel and delta-front sandstones are very fine to fine grained, quartz poor (39%), and sparsely bu rowed by Ophiomorpha. The beach-bar deposits include shoreface-beach sandstone, siltstone, and shale, and tidal-channel and washover sandstones. Lower-shoreface deposits include parallel-laminated, rippled sandstone and bioturbated shale and siltstone. Middle-shoreface sandstone consists of a subparallel-laminated, rippled, and locally burrowed lower part, and a planar-cross-bedded and commonly burrowed upper part. Upper-shoreface-beach deposits consist of planar-cross-bedded, sparsely burrowed sandstone and lenticular, festooned, rippled, burrowed sandstone grading upward into subparallel-laminated, festooned, burrowed sandstone. The shoreface-beach deposits are dissected by bidirectionally End_Page 451------------------------------ festooned and planar-cross-bedded tidal-channel sandstone and festooned, burrowed washover sandstone. The beach-bar sandstones are very fine to medium grained, quartz rich (54%), and commonly burrowed by Ophiomorpha. Differentiation of Pictured Cliffs Sandstone depositional environments led to recognition of deltaic and back-barrier coal deposits of the overlying Fruitland Formation. End_of_Article - Last_Page 452------------

Distribution and Continuity of Sandstone Reservoirs

Includes Parts 1 and 2 This paper presents brief discussions of the three most importantdepositional environments of sandstone reservoirs. Criteria for identifyingsandstones from conventional data are presented, along with conceptual modelsfor predicting their distribution and internal reservoir characteristics. Introduction Effective maximum exploitation of a hydrocarbon accumulation requires fullunderstanding of the reservoir beds and the pore space they contain.Fundamental research on clastic sediments by the petroleum industry, universities, and government agencies has produced a wealth of publishedinformation on the distribution and continuity of sandstones. Criteria forrecognizing the various types of sandstones utilizing conventional subsurfacedata, such as cores, cuttings, and well logs, are reasonably well established.Conceptual models for predicting or determining sand body distribution, predicting or determining sand body distribution, continuity, and internalcharacteristics also are available. Any method of oil- or gas-field developmentthat does not take advantage of these conceptual models and criteria must beconsidered negligent. The distribution, continuity, and internal characteristics of sandstones arecontrolled primarily by original environments of deposition. Anyone who isseriously involved in determining the distribution and continuity ofsandstones, whether on a local or regional basis, will profit substantially bystudying the literature and developing a thorough understanding of theseenvironments. Therefore, this summary paper on the distribution and continuity ofsandstone reservoirs consists of two parts. Part 1 consists of briefdiscussions of the three most Part 1 consists of brief discussions of the threemost significant sandstone depositional environments:continental (alluvialfan, braided stream, meandering stream, and aeolian),transitional (deltaicand coastal barrier islands, tidal channels, and aeolian and transgressivemarine), anddeep marine (turbidities related to submarine canyon-fansystems). (See Fig. 1.) These key sedimentary environments are reviewed through examination of modemexamples and ancient analogs. Criteria for identifying sandstones fromconventional data are presented with the conceptual models necessary forpredicting their distribution and internal reservoir characteristics. Part 2 is a bibliographic source document. It includes a geneticclassification of environments of sand deposition and lists, by depositionalenvironments and geographic occurrence, the significant literature on ancientsandstones. Some 250 selected references are included. The scientist and engineer who together integrate appropriately thecriteria, principles, and models of sandstone deposition presented here withother subsurface engineering data should benefit from the synergism bound tooccur and, thus, should be better able to solve the practical reservoirproblems. Distribution and Continuity of Sandstone Reservoirs Our present knowledge and understanding of the factors that control thedistribution and continuity of sandstones are based on the research on Recentsediments and on the study of ancient clastic sediments. The following discussion of the distribution and continuity of sandstonereservoirs describes those sand bodies believed to predominate in the spectrumof sandstone reservoirs. JPT P. 776

Differentiation of Sandstone Depositional Environments in Pennsylvanian Breathitt Formation of Northeastern Kentucky and Southwestern West Virginia: ABSTRACT

Differentiation of Sandstone Depositional Environments in Pennsylvanian Breathitt Formation of Northeastern Kentucky and Southwestern West Virginia: ABSTRACT

Symmetry, Stratigraphy, and Petrography of Cyclic Cretaceous Deposits of San Juan Basin: ABSTRACT

Late Cretaceous strata of the San Juan basin consist of cyclically interstratified non-marine, nearshore marine, and offshore marine clastic sediments which were deposited both during marine transgressions and regressions. Thickness of the transgressive and regressive parts of these cyclic sequences varies, permitting subdivision into two types of cycles: symmetrical and asymmetrical. In symmetrical cycles the thickness of transgressive and regressive parts are nearly equal; in asymmetrical cycles the transgressive sandstone is absent. The Hosta-Point Lookout wedge is an example of a symmetrical cycle. At its base the transgressive marine Hosta Sandstone overlies continental strata of the Crevasse Canyon Formation. The Hosta Sandstone grades upward into the offshore marine Satan Shale. The Satan Shale marks the midpoint of the cycle and the maximum marine inundation; it grades upward into the regressive marine Point Lookout Sandstone. The Point Lookout is overlain by the continental Menefee Formation. Southwestward, toward the former shoreline, the Satan Shale pinches out and the transgressive and regressive sandstones merge into a single massive sandstone, which still farther southwestward grades into continental strata. The Mulatto-Dalton cycle is asymmetrical for it lacks a basal transgressive sandstone. Instead, the offshore Mulatto Shale directly overlies the continental Dilco Coal with only scattered marine sand lenses at the contact. The Mulatto Shale grades southwestward (toward former shoreline) and upward into the regressive marine Dalton Sandstone which in turn grades southwestward into, and is overlain by, continental deposits of the Crevasse Canyon Formation. Petrography is closely related to the sandstone depositional environments as follows. Regressive sandstone type: Upward increase in maximum and median grain diameter; upward decrease in abundance of primary dolomite grains. These vertical changes reflect progressive shallowing of the basin during regression. Transgressive sandstone type: Upward decrease in maximum and median grain diameter; upward increase in abundance of primary dolomite grains. These vertical changes reflect progressive deepening during transgression. Non-marine sandstone type: Wide range of grain sizes; primary dolomite grains absent; abundant carbonaceous material; higher proportion of non-quartz detritus. Petrography and the cycle concept are useful for recognizing and solving correlation problems.

Symmetry, Stratigraphy, and Petrography of Cyclic Cretaceous Deposits in San Juan Basin

Late Cretaceous strata of the San Juan basin consist of cyclically interstratified non-marine, nearshore marine, and offshore marine clastic sediments which were deposited both during marine transgressions and regressions. Thickness of the transgressive and regressive parts of these cyclic sequences varies, permitting subdivision into two types of cycles: symmetrical and asymmetrical. In symmetrical cycles the thickness of transgressive and regressive parts are nearly equal; in asymmetrical cycles the transgressive sandstone is absent. The Hosta-Point Lookout wedge is an example of a symmetrical cycle. At its base the transgressive marine Hosta Sandstone overlies continental strata of the Crevasse Canyon Formation. The Hosta Sandstone grades upward into the offshore marine Satan Shale. The Satan Shale marks the midpoint of the cycle and the maximum marine inundation; it grades upward into the regressive marine Point Lookout Sandstone. The Point Lookout is overlain by the continental Menefee Formation. Southwestward, toward the former shoreline, the Satan Shale pinches out and the transgressive and regressive sandstones merge into a single massive sandstone, which still farther southwestward grades into continental strata. The Mulatto-Dalton cycle is asymmetrical for it lacks a basal transgressive sandstone. Instead, the offshore Mulatto Shale directly overlies the continental Dilco Coal with only scattered marine sand lenses at the contact. The Mulatto Shale grades southwestward (toward former shoreline) and upward into the regressive marine Dalton Sandstone which in turn grades southwestward into, and is overlain by, continental deposits of the Crevasse Canyon Formation. Petrography is closely related to the sandstone depositional environments as follows. Regressive sandstone type: Upward increase in maximum and median grain diameter; upward decrease in abundance of primary dolomite grains. These vertical changes reflect progressive shallowing of the basin during regression. Transgressive sandstone type: Upward decrease in maximum and median grain diameter; upward increase in abundance of primary dolomite grains. These vertical changes reflect progressive deepening during transgression. Non-marine sandstone type: Wide range of grain sizes; primary dolomite grains absent; abundant carbonaceous material; higher proportion of non-quartz detritus. Petrography and the cycle concept are useful for recognizing and solving correlation problems.

Symmetry, Stratigraphy, and Petrography of Cyclic Cretaceous Deposits of the San Juan Basin: ABSTRACT

Late Cretaceous strata of the San Juan Basin consist cyclically interstratified non-marine, nearshore marine, and offshore marine clastic sediments which were deposited both during marine transgressions and regressions. Thickness of the transgressive and regressive parts of these cyclic sequences varies, permitting subdivision into two types of cycles: symmetrical and asymmetrical. In symmetrical cycles the thickness of transgressive and regressive parts are nearly equal; in asymmetrical cycles the transgressive sandstone is thin or absent. The Hosta-Point Lookout wedge is an example of a symmetrical cycle. At its base the transgressive marine Hosta Sandstone overlies non-marine strata of the Crevasse Canyon Formation. The Hosta Sandstone grades upward into the offshore marine Satan Shale. The Satan Shale marks the mid-point of the cycle and the maximum marine inundation; it grades upward into the regressive marine Point Lookout Sandstone. The Point Lookout is overlain by the non-marine Menefee Formation. Southwestward, toward the former shoreline, the Satan Shale pinches out and the transgressive and regressive sandstones merge into a single massive sandstone, which is also called the Point Lookout Sandstone. Still farther southwestward this massive sandstone grades into non-marine strata of the Crevasse Canyon and Mene ee formations. The Mulatto-Dalton cycle is asymmetrical for it lacks a basal transgressive sandstone. Instead, the offshore Mulatto Shale directly overlies the non-marine Dilco Coal with only scattered marine sand lenses at the contact. The Mulatto Shale grades southwestward (toward the former shoreline) and upward into the regressive marine Dalton Sandstone which in turn grades southwestward into, and is overlain by, non-marine deposits of the Crevasse Canyon Formation. Petrography is closely related to the sandstone depositional environments as follows. Table These petrographic properties may be used to identify and correlate units in problem areas. End_of_Article - Last_Page 369------------