Massive Sandstone Beds Research Articles

Barrier Island Depositional Systems in Black Warrior Basin, Lower Pennsylvanian (Pottsville) in Northwestern Alabama: ABSTRACT

The basal Pennsylvanian lower Pottsville Formation in the Black Warrior basin of northwestern Alabama is part of a southwestward-thickening wedge of terrigenous sediments consisting of orthoquartzitic sandstone, siltstone, and shales with discontinuous coals. The present study delineates each lower Pottsville lithofacies, to confirm or refute a barrier-island model. Preliminary interpretation of lithofacies using lithologic criteria, sedimentary structures, and fossil assemblages confirms a barrier deposition system. Exposures along I-65 in southern Cullman County are interpreted to represent lagoonal deposits based on the high percentage of mud-sized material, massive and structureless washover sandstone beds, and highly rippled interbedded sandstones and silty shales that contain microcross-stratification. Exposures in northern Cullman County are interpreted to represent tidal channel-fill deposits, flood tidal sequences, and possible foreshore sandstone deposits. Tidal channel-fill deposits are recognized by coarse sandstone textures with pebble lags, large-scale cross-bedding, and their geometry. Flood tidal sequences are recognized by stacked cross-bedded sets and additional sedimentary structures. Foreshore deposits are interpreted based on the orientation of low-angle planar bedding.

Marine Destruction of Eolian Sand Seas: Origin of Mass Flows

ABSTRACT The basal marine sandstone of the Upper Jurassic Curtis Formation of northeastern Utah was deposited in a shallow, tide-dominated sea during marine transgression across the Entrada eolian sand sea. Entrada dunes within the study area are interpreted to have been over 100 m in height. Eolian paleotopographic highs along the Entrada-Curtis contact, however, are only up to 7 m high, clearly indicating that major portions of Entrada dunes were destroyed. Within the transgressive marine deposits are abundant massive sandstone beds up to 12 m thick that are interpreted as mass-flow deposits derived from the marine destruction of the large Entrada dunes. These massive sandstones are lenticular and locally contain clay and sandstone clasts, faint horizontal and contorted laminae, and dish s ructures. Some massive sandstones were emplaced with significant scour of underlying deposits, but others show nonerosional basal contacts that bury and perfectly preserve underlying marine megaripples and trains of megaripples. Most mass flows were probably initiated during marine storm events (surges) that undercut dunes and resulted in slumpage followed immediately by liquefaction and flowage. Liquefaction in water-saturated, basal portions of dunes probably also resulted in failure and flowage. Interpreted travel distances of a few kilometers over the gently sloping Curtis shelf suggest that liquefied flows evolved into high-density turbidity currents. Characteristics of the massive sandstone deposits, however, indicate that final deposition was from liquefied flows. The flows, there ore, apparently evolved from liquefied flows to high-density turbidity currents and then back to liquefied flows as momentum was lost. We suggest that slumping, liquefaction, and mass flowage of dune sands (which are very prone to liquefaction) commonly occur along the coastlines of some eolian sand seas and are significant mechanisms for the destruction of dunes during marine transgressions and for offshore transport of sand to the shelf. These mechanisms can also operate in flooded interdune areas during major storms. Available literature suggests that massive sandstones are abundant along eolian-marine contacts where dune topography has been largely destroyed and are relatively uncommon where dunes are preserved nearly intact. The primary factors that control the frequency of mass-flow events during marine transgression, and similarly whether dune topography is preserved or destroyed, are 1) the energy and nature f the transgressing marine environment, 2) the rate of transgression, and 3) the abundance of sand-stabilizing early cements.

Cardium Formation at Ricinus Field, Alberta: A Channel Cut and Filled by Turbidity Currents in Cretaceous Western Interior Seaway

The Upper Cretaceous (Turonian) Cardium Formation forms a series of long, narrow reservoirs in the subsurface of southern Alberta. Most of the sandstones show evidence of deposition by storm currents many tens of kilometers offshore. However, Ricinus field is different from all other Cardium fields: the sandstone body (Ricinus Member: new name) is up to 20 m thick compared with a Cardium average of only a few meters, and well-log cross sections indicate that this 20-m sandstone rests in a channel up to 55 km long, 8 km wide (before palinspastic reconstruction) and 20-40 m deep. Study of 71 cores showed that the channel fill consists of massive sandstone beds up to several meters thick, and thinner graded beds that are either massive or contain the sequence of sedimentary tructures from parallel lamination to ripple cross-lamination (ABC to BC beds in the Bouma terminology for turbidites). Most of the sandstones have sharp bases, many with rip-up mudstone clasts. A thin mudstone layer commonly occurs between individual sandstones. Wave-formed structures such as symmetrical ripple cross-lamination and hummocky cross-stratification are rare in the Ricinus sandstones, despite being characteristic of the Cardium in most other fields. Thus, the nature of the channel fill indicates deposition in depths mostly below storm wave base, probably by turbidity currents. The channel also may have been eroded by turbidity currents during a brief lowstand of sea level. This erosion during lowstand may have far-reaching implications for style and distance of sand transpor , for sand-body geometry, and for the nature of reservoir margins in other linear sandstones in shallow epeiric seas.

茨城県，つく波変成岩類の層序と変成分帯

In the Tsukuba district the strata of metasediments can be classified into the Hirasawa, Tojoji and Yuki-iri Formations in the ascending order of stratigraphic succession based on sedimentary structures. The Hirasawa Formation, over 1500m in thickness, consists largely of a very thin alternation of mudstone and siltstone or sandstone (from 0.3 to 1cm thick). The Tojoji Formation, from 300 to 600m in thickness, is mainly composed of an alternation of relatively thick mudstone and siltstone or sandstone (from 10 to 50cm thick) together with subordinate massive sandstone beds. The Yuki-iri Formation, over 600m in thickness, consists mostly of a thin alternation of mudstone and siltstone or sandstone (from 1 to 3cm thick), though it contains some massive mudstone layers. The metamorphic terrane is divided into three zones, A, B and C, in the order of increasing metamorphic grade on the basis of mineral parageneses in pelites and psammites. The characteristic mineral assemblages of the three zones as follows. Zone A: Muscovite+plagioclase ± orthoclase ± andalusite. Zone B: Fibrolite+muscovite+orthoclase+plagioclase+±cordierite. Zone C: Fibrolite+orthoclase+plagioclase+cordierite ± pyralspite. Biotite, quartz and graphite are always present in any of these assemblages. The geological and petrological facts indicate that the thermal structure of this district is discordant with stratigraphic horizon. The distribution of metamorphic temperature, however, seems to be dependent on the shape of biotite granite mass. It can be explained by the idea that these metamorphites were subjected to contact metamorphism in the amphibolite facies by the biotite granite intrusion. The results of K-Ar dating (Shiba et al., 1979) support this explanation. The tectonic movement in this district might have begun after later Jurassic and continued to early Tertiary time.

Sedimentation on the Front of Eocene Gilbert-type Deltas, Washakie Basin, Wyoming

ABSTRACT The transition from alluvial to lacustrine rocks in the Laney Member of the Green River Formation includes Gilbert-type deltas whose depositional features provide information about the history and nature of Lake Gosiute, and document proximal to distal sedimentation on the delta fronts. Gilbert-type deltaic rocks in the Laney are composed of cycles each consisting of constructional and destructional phases. The constructional phases are represented by an upward-coarsening sequence produced by lakeward progradation of delta topset and foreset beds over prodeltaic sediments. During the destructional phase erosion and reworking of delta-plain and -slope beds resulted in formation of an erosional surface, and locally, a sandstone shoreline veneer. These features of Laney deltaic deposits re similar to constructional and destructional phases of late Quaternary and modern Gilbert-type delta deposits of the Truckee River at Pyramid Lake, Nevada. They are attributed to fluctuation in lake level or shifting of the stream mouth entering the lake. The most characteristic feature of the delta deposits is foreset bedding with depositional dips of up to 20 degrees. The maximum thicknesses of foreset deposits range from 10 to 25 meters. The geometry of the foreset deposits suggests that the lake was shallow with maximum depths of 25 meters where deltas were constructed. Foreset beds grade upward into flat-lying sandstone and mudrock topset beds, and grade downward into flat-lying mudrock bottomset beds. The delta fronts consist of repetitive sequences of sandstone and mudrock with sporadic, thick, massive sandstone beds. In the Bridger and Washakie Basins local foundering of deltaic sandstone and mudrock into lacustrine oil shale resulted in large load casts, slump folds, and sandstone pillows that partly or wholly obliterated orig nal bedding features of topset, foreset, and bottomset beds. Proximal to distal delta-front sedimentation patterns include: thinning of stratigraphic intervals of 50 to 70 percent; increase in the ratio of mudrock to sandstone; and decrease in the total number of beds in a stratigraphic interval. Bedding sequences in delta-front rocks are 1) ripple-bedded fine-grained sandstone overlain by parallel-laminated mudrock; 2) ripple-bedded fine-grained sandstone, parallel-laminated fine-grained sandstone, and parallel-laminated mudrock; and 3) parallel-laminated fine-grained sandstone overlain by parallel-laminated mudrock. These sequences were produced by interflow and mixing of sediment-laden stream water in lake water of equal density, and by wave action on the delta front.

Geology of South Bosco-Duson-Ridge Area, Acadia and Lafayette Parishes, Louisiana: ABSTRACT

The South Bosco-Duson-Ridge fields area is in the Oligocene and Miocene oil- and gas-producing trends of Acadia and Lafayette Parishes, Louisiana. In wells drilled to sufficient depth, three facies were found: End_Page 2319------------------------------ (1) a Pliocene and Miocene nearshore to continental massive sandstone facies; (2) an early Miocene and Oligocene continental-shelf facies of alternating sandstone and shale; and (3) a thick bathyal shale facies of Oligocene age. Oil and gas production in the area is confined almost entirely to sandstone beds in the continental-shelf facies. South Bosco-Duson-Ridge fields are on a faulted, elongated north-south anticline that trends normal to the regional stratigraphic strike. All faults are normal and are either down-to-the-basin or up-to-the-basin. The down-to-the-basin faults are regional and are parallel with the regional stratigraphic strike. The up-to-the-basin faults are compensating faults confined to the South Bosco-Duson-Ridge complex. The fault throw generally increases with depth. All the faults die out upward in the section in or before reaching early Miocene sedimentary rocks. Strata thicken into the downthrown sides of the faults and thin toward the crest and over the highest parts of the structure. The amounts of thickening or thinning generally increase with depth. Thus, fault movement and anticlinal folding were contemporaneous with sedimentation, continuously from Oligocene into Miocene time, and were most intense during Oligocene time. The South Bosco-Duson-Ridge structure probably originated from faulting and anticlinal folding on the continental slope during Oligocene time. Structural growth was greatest where the structure was in the unstable environment of the hinge line (or shelf edge). Structural activity continued during the deposition of the neritic sediments of the Oligocene and early Miocene but at a steadily reduced rate. The structure was buried by a great thickness of nearshore and continental massive sandstone beds during Miocene and Pliocene time. End_of_Article - Last_Page 2320------------

Top-and-bottoming by means of jointing

Abstract The use of graded bedding to determine the direction of younging of beds is difficult where greywackes consist of massive sandstone beds with but thin argillite partings.

Ouachita Mountain Core Area, Montgomery County, Arkansas

The purpose of this study was to investigate in detail the core area of the Ouachita Mountains of southwestern Arkansas. As work progressed it was discovered that High Peak and Wheeler Mountain ridges are not homoclinal, as originally mapped by Miser and Purdue, but rather are anticlinal. According to our interpretation there are only two outcrop areas of Collier shale in the Crystal Mountains: those along upper Collier Creek and upper Huddleston Creek. This fact is stratigraphically significant in that no dark bluish gray limestone was found by the writers in these remaining two outcrop areas of Collier shale. Another significant change in the stratigraphy is that of the thickness and lithologic character of the Crystal Mountain sandstone, which Miser and Purdue d scribed as almost entirely sandstone and as being 850 feet thick. Pitt discovered that the measurable interval of the Crystal Mountain sandstone in the Crystal Mountains is only 180-320+feet. Lithologically the measured interval consists of two massive sandstone beds, 30-80 feet in thickness, separated by about 100 feet of thin beds of siltstone and shale. Locally as much as 50 feet or possibly slightly more of interbedded sandstone and shale makes up the uppermost member in the Crystal Mountains. In the Mount Ida area north of the Crystal Mountains the Crystal Mountain sandstone ranges in thickness from 280 to 370 feet because the uppermost member is thicker than it is in the Crystal Mountains. No conglomerate or other suggestion of an unconformity was found at the base of the Crystal Mountain sandstone; the writers therefore believe that the Collier shale is probably Ordovician in age rather than Cambrian. The outcrop of supposed Collier shale north of Wheeler Mountain and near the town of Mount Ida is actually Mazarn shale. This Mount Ida area is one of sharp anticlinal folds with gentle westward plunge. Most of the Crystal Mountain sandstone ridges have been overturned southward. Faulting is rare throughout the Mount Ida area. The few observed faults are tear faults, but their presence suggests that minor thrust faults also may be present.