Lithofacies Distribution Research Articles

Recurrent Species Associations and Species Diversity of Cytheracean Ostracodes in Upper Austin and Lower Taylor Groups (Campanian, Upper Cretaceous), Travis County, Texas: ABSTRACT

ABSTRACT Assemblages of cytheracean ostracodes from the Dessau, Burditt, and Sprinkle formations of the upper Austin and lower Taylor groups of Travis County, Texas, were examined in order to identify recurring species associations and the paleoenvironmental factors that control their stratigraphic distribution. From Q-mode cluster analysis, six sample-groups were identified, all of which correspond closely to observable lithofacies. Four recurrent species associations were identified from the R-mode cluster analysis and were found to correspond to four of the six sample-groups. Indices of species diversity and of its components, species richness and species equitability, show noticeable changes from one lithofacies to another, with the greatest changes occurring at the disconformable Dessau-Burditt and Burditt-Sprinkle (Austin-Taylor) contacts. The stratigraphic distributions of cytheracean ostracode faunas in the upper Austin and lower Taylor appear to be controlled by the distribution of lithofacies. Some of the faunas, however, differ primarily in abundances of species, as opposed to containing different species. Such faunas can be differentiated by comparing values of species diversity and its components. Plotted trend-curves of the indices provide visual aids for this purpose. The parallel shapes of the trend-curves for two outcrops suggest potential use of diversity trend-curves for stratigraphic correlation, and major breaks in these curves at known disconformities show potential for detecting previously unrecognized disconformities. Appearances and disappearances of a few species, including Alatacythere cheethami, Hazelina austinensis, Schuleridea travisensis, and Loxoconcha retiolata, may be temporally significant.

Upper Mission Canyon (Mississippian) Cyclicity and Hydrocarbon Occurrence, North-Central North Dakota: ABSTRACT

The upper Mission Canyon Formation along the east flank of the Williston basin represents several upward-shoaling cycles within an overall regressive marine sequence. Individual cycles grade from offshore shelf carbonates eastward into restricted marginal marine evaporites. This depositional pattern and subsequent diagenesis have produced numerous prolific hydrocarbon traps. The relationship of hydrocarbon occurrence to facies distribution, paleostructure, and porosity development is discernable by constructing a variety of isopach, lithofacies, and porosity maps. Two areas in the vicinity of Chola-Mackobee Coulee and Glenburn fields permit detailed analysis of the Bluell, Sherwood, Mohall, and Glenburn cycles. Anhydrite distribution and thickness variation within individual Mission Canyon cycles most closely correspond to the pattern of hydrocarbon occurrence. Other major factors governing such occurrence include the lateral distribution and succession of carbonate bank, dolomite, anhydrite, and siliciclastic lithofacies. End_of_Article - Last_Page 1335------------

Lineaments and Their Tectonic Implications in Rocky Mountains and Adjacent Plains Region: ABSTRACT

Two orthogonal sets of lineaments in Phanerozoic rocks of the Rocky Mountains and adjacent plains region probably reflect recurrent structural movement along corresponding fractures in the underlying igneous and metamorphic rocks. The lineaments seem to have been primarily paleotopographic features that affected the depositional and erosional margins, thicknesses, and the distribution of lithofacies of Phanerozoic strata. One set is oriented near the cardinal points of the compass, approximately N5°-15°E and N75°-85°W;the other set is oriented diagonally, about N50°-60°E and N30°-40°W. At small scales, the crosscutting lineaments of either set suggest primarily vertical movements of rectangular blocks along through-going rectilinear fractures in the basement rocks. At larger scales, the differential movement of these blocks apparently was propagated upward through the strata and formed a variety of structures, many of which are en echelon. Blocks in the region moved at different times, and they commonly rotated about horizontal axes, as indicated by lateral differences in rates of associated sedimentation and by structural features along the lineaments. Throughout most of the Phanerozoic, the movements seem to have been mainly along the diagonal set (northeast, northwest) of lineaments, but the cardinal set (north-south, east-west) also influenced the development of Laramide structures and the present landscape in the Rocky Mountain region. The structural stresses, which were released along the two sets of lineaments, may reflect plate movements, and they probably are related to orogenies caused either by plate collisions or by rifting and continental fragmentation. End_of_Article - Last_Page 1349------------

Lithofacies distribution of the Permian‐Triassic rocks in the Middle East:A Reply

Lithofacies distribution of the Permian‐Triassic rocks in the Middle East:A Reply

Recent and Pleistocene beach/dune sequences, western Australia

Wave-dominated sandy shores occur along much of the coast of Western Australia. Despite local variations there is a characteristic distribution of lithofacies (corresponding to different geomorphic zones). Five lithofacies are recognised: (1) trough-bedded sand/gravel; (2) laminated sand; (3) laminated/bubble sand; (4) laminated/disrupted sand; and (5) aeolian cross-stratified sand. The trough-bedded sand/gravel lithofacies is being deposited in the shallow shoreface below LWL. The laminated sand and laminated/bubble sand lithofacies are sands with gravel layers being deposited on the foreshore swash zone; extensive bubble (or vesicular) sand is common towards HWL especially in berms. The laminated/disrupted sand lithofacies is being deposited on the backshore between HWL and storm water levels and consists of horizontally layered to homogeneous sands with storm debris, especially wood, weed and floatable skeletons (e.g. Sepla and Spirula). The aeolian cross-stratified sand lithofacies is forming in beach ridge/dune areas and consists of fine sands with large-scale, generally landward-dipping forests; soils and rootlets are common. Recognition of these lithofacies within a sedimentary sequence enables reconstruction of gross shoreline conditions in terms of wave and eolian environments, tidal and storm heights, and palaeogeography. Each of these lithofacies with their characteristic features is recognised in Pleistocene sequences in Perth Basin. The Pleistocene sequences fit a model of coastal progradation with the trough-bedded sand/gravel lithofacies at the base and the aeolian sand lithofacies at the top. The value of such a stratigraphic sequence, however, extends beyond the Pleistocene.

A glacio-isostatic facies model and amino acid stratigraphy for late Quaternary events in Spitsbergen and the Arctic

Strong early Holocene crustal uplift over the Spitsbergen archipelago reflects disappearance of an ice mass centred just north-east of the archipelago and which decayed rapidly just after 10,000 BP after a maximum extension between 12,600 and 10,000 BP. From the lithofacies distributions associated with these events a glacio-isostatic facies model can be defined which, combined with analyses of amino acid racemization, provides a valuable stratigraphic method for correlating pre-Holocene glacio-isostatic events. These are correlated with events in Greenland, and both are contrasted with Weichselian glacial events at the southern margins of the two great Northern Hemisphere ice sheets and with contemporary water mass changes in the North Atlantic and Norwegian Sea. The geographical variation in glacier response through time is explained by three principal climatic circulation patterns.

Lithofacies distribution of the Permian‐Triassic rocks in the Middle East: A Discussion

The Permian and Triassic rocks of the Middle East are two of the older stratigraphic problems in that area. Dr. Sharief's article on these rocks in the January, 1982 issue of JOURNAL OF PETROLEUM GEOLOGY presents an interesting synopsis of their facies and paleoenvironments of deposition. However, some points may need further clarification.

Geological Heterogeneities Important to Future Enhanced Recovery in Carbonate Reservoirs of Upper Ordovician Red River Formation at Cabin Creek Field, Montana

Abstract Several different pore systems are present in dolomite reservoir rocks of the Red River formation (Upper Ordovician) at Cabin Creek field, MT. Each system is associated with particular depositional environments and diagenetic regimes. Pore geometry is mostly a function of the size and shape of the dolomite crystals composing the rock matrix. Mean pore-throat size, a statistical measure of pore geometry, increases as porosity percent increases, depending on the type of dolomite. This relationship permits prediction of reservoir pore geometry and a better assessment of recovery efficiency once lithofacies distribution, porosity origin, and diagenetic history have been determined for the reservoir by study of cores and rock thin-sections.

LITHOFACIES DISTRIBUTION OF THE PERMIAN‐TRIASSIC ROCKS IN THE MIDDLE EAST

The lithofacies distribution of the Permian‐Triassic sequence across the Middle East region shows a great diversity of depositional sedimentary facies laterally as well as vertically. During Permian‐Middle Triassic time, a clastic‐carbonate shelf facies characterizes most of the Middle East region. This platform facies is marked by a number of depositional sedimentary facies which is related to a wide variety of environments, from non‐marine, supratidal and restricted marine shelf to open‐sea and deeper‐shelf deposition.The distribution of the Upper Triassic lithofacies is marked by sharply‐differentiated depositional patterns. Except for Iran, N Iraq, SE Turkey and central Syria, the passage from the Middle Triassic to the Upper Triassic in the region is marked either by non‐deposition or continental strata, or carbonate‐evaporite sequence. Marine, carbonate and shale deposits of open‐shelf facies continued to be formed in W Iran, N Iraq and SE Turkey. A large amount of richly fossiliferous clastic, neritic deposits accumulated in central and E parts of Iran. In contrast, a terrigenous‐flysch‐like sequence continued to accumulate in the extreme NE Iran since early Triassic time.

Sedimentology and Distinction of Carbonate Buildups: Middle Ordovician, East Tennessee

ABSTRACT Investigation of extensive skeletal grainstone deposits that comprise much of the Middle Ordovician sequence in East Tennessee has resulted in the recognition of two distinct carbonate buildup complexes. The Rockdell Formation comprises abundant pelmatozoan-bryozoan grainstones and packstones and lesser deposits of lime wackestone. These deposits represent carbonate sand shoals, consisting of a mixture of in situ and transported skeletal grains, which surround relatively small, isolated to anastomosing, lime-mud mounds. The Rockdell buildup was developed in shallow-water, high-energy conditions on a relatively stable platform. The Holston Formation is dominated by bryozoan-pelmatozoan packstones that surround roughly elliptical masses of bryozoan wackestone/boundstone. The Holston rep esents a series of lime-mud bryozoan patch-reefs that were surrounded by piles of in situ skeletal sand produced in pelmatozoan-bryozoan thickets. The Holston buildup developed in deeper water on the outer platform or perhaps downslope. Recognition and distinction of these two buildups is based on consideration of a number of criteria including 1) color, 2) overall composition and distribution of flora and fauna, 3) composition and distribution of bryozoan fauna, 4) types and distribution of component lithofacies, and 5) character of associated lime-mud deposits. Distinction of these buildups has major importance in the determination of East Tennessee paleogeography during the Middle Ordovician and also has implications for possible hydrocarbon exploration in these deposits. The criteria applied here may be useful in making distinctions among other carbonate buildups in the geologic record.

Carbonate Sedimentation of Reef and Associated Shoal-Water Facies, Sligo Formation (Aptian), Black Lake Field, Natchitoches Parish, Louisiana: ABSTRACT

The Black Lake field is one of the larger Lower Cretaceous carbonate hydrocarbon reservoirs along the U.S. Gulf Coast. The field produces from the Pettet porosity zone of the upper Sligo Formation. This porous zone coincides with a variety of carbonate facies that were deposited on a wave-dominated shelf as caprinid reefs and associated shoal-water deposits. Distinctive associations of lithologies, textures, fabrics, structures, and faunas provided the basis for recognizing seven major carbonate lithofacies in the field. Lithofacies present in the field include (1) caprinid, (2) oncolite, (3) oolite, (4) bioclastic, (5) bioclastic micritic, (6) foraminiferal, and (7) micrite lithotypes. A sequence of lithofacies maps and stratigraphic cross sections describe the areal geometry, distribution, growth, and movement of the various major carbonate lithofacies within the field through a short span of geologic time. Sediments deposited under the caprinid reef in the field were predominantly foraminiferal and bioclastic lime mudstones and wackestones characterized by massive bedding, bioturbation, mollusk debris, and abundant remains of Orbitolina texana. Caprinids initially began flourishing in the northeastern part of the field as one distinct circular body surrounded by mud-supported sediments. The caprinid lithofacies migrated in a southwesterly direction, suggesting that the predominant movement of longshore currents was from the northeast to the southwest. The caprinid formed a distinct linear carbonate buildup that trended in a northeast-southwest direction. Bioclastic micritic and bioclastic sediments formed on the landward and seaward sides of the reef trend, respectively. This demonstrates the the reef acted as a local wave-resistant barrier or baffle that allowed muddier bioclastic wackestones to accumulate behind (landward) the caprinid reef trend. The cross-sectional geometry of the caprinid lithofacies along with the dominance of reef debris landward of the main reef axis suggests that the caprinid reef developed on a wave-dominated shelf. As the reef development continued, a landward shift in local energy levels occurred. Along with the shift of energy level, the position of the longshore current also moved landward. This allowed stronger cur ents to move behind the reef trend (landward) and form and deposit coarser-grained sediments. The elongate reef trend was severed presumably by longshore and tidal currents. The resultant buildups were separated by a sub-perpendicular trend that consisted of bioclastic sediments which most likely represented a tidal channel through the caprinid reef. Bioclastic micritic sediments accumulated on the lee side of the reef trend in current sheltered areas. Caprinid reef growth stabilized and shoal-water deposits began to develop on the landward side of the reef trend. These shoal-water deposits consist of oolite and oncolite shoals and bioclastic reef-flank sediments deposited laterally adjacent to the caprinid lithofacies. The shoal-water deposits continued to develop and prograded over the area formerly occupied by the caprinid reef trend. End_of_Article - Last_Page 601------------

Depositional Patterns of a Silurian Shelf Sand in Central Appalachians: ABSTRACT

The Keefer Sandstone in the subsurface of West Virginia and Kentucky, where it produces small volumes of natural gas, was deposited on the western shelf of the Appalachian basin. The formation is a dolomitic quartzarenite and quartzwacke and ranges from 13 to 50 ft (4 to 15 m) thick. As interpreted from four cores and isopach and lithofacies maps, the sand was transported by longshore currents from a southeastern source area and laid down in a variety of environments. In Kentucky, Keefer deposition was on a wave-dominated coast. The rocks are characterized by physical sedimentary structures and textures which developed under high-energy conditions, and the formation is divided into shoreface and foreshore facies. In adjacent West Virginia, however, Keefer deposition occur ed offshore in water near the depth of wave base, swept out onto the shelf by storm-generated currents. Sedimentary structures and textures indicate a lower energy environment, bioturbation is more common, and the formation contains a greater amount of shale. The isopach map shows two linear tracts of thick sand in this offshore facies that may represent a coalescence of subtidal bars on the shelf. Between major sand bodies, the Keefer becomes appreciably thinner and is interbedded with fossiliferous dolomite. In the basin center of West Virginia, sandstone is replaced by shale. Thus, the geographical distribution of lithofacies shows a transition of shelf environments within a blanket sandstone. In all cores, regardless of depositional facies, the sandstone displays evidence of aggradin sedimentation; sedimentation exceeded subsidence, and the sand body built upward into shallower water. End_of_Article - Last_Page 1175------------

Sedimentation and Depositional Environments Between Mistaya and Survey Peak Formations, Western Alberta, Canada: ABSTRACT

A regressive-transgressive cycle is recognized within the Mistaya Formation (uppermost Cambrian) and the basal silty member of the Survey Peak Formation (Ordovician) in western Alberta. The regressive cycle consists of shallow-water peritidal carbonates which reflect a gradual shallowing of the carbonate-shoal complex, culminating in a subtidal to supratidal sequence. Lithofacies recognized within this basal sequence A are: (1) interbedded biosparite and millimeter-laminated biomicrite (open platform-subtidal shelf); and (2) interfingering oosparite, intraclastic biosparite, and biosparite (oolitic shoal complex). These lithofacies grade vertically into sequence B of: (1) laminated biosparite and biomicrite (open platform-subtidal shelf); (2) algal Figure biolithite composed of algal thrombolites, and columnar and polygonal stromatolites (bioherm complex); (3) cross-stratified biosparite and intrasparite (tidal channels); and (4) dolomitic intramicrite, laminated mat algae, and laminated and fenestral dolomite (supratidal flat). The distribution of lithofacies reflects a shallowing of the carbonate complex, culminating in the intertidal stromatolites and supratidal mat algae developing on top of the thrombolitic bioherm. End_Page 626------------------------------ The transgressive cycle marks the drowning of the thrombolitic bioherm by a rise in sea level. Lithofacies recognized within the transgressive sequence C are: (1) millimeter-laminated micrite and biomicrite (subtidal shelf); and (2) tabular-bedded biosparite (open platform). The lateral expansion of the platform biosparite sands over the thrombolitic bioherm, intertidal, and supratidal environments coincides with the mass trilobite extinction between the deposition of the Mistaya and Survey Peak Formations. End_of_Article - Last_Page 627------------

Lithofacies distribution of the Permian-Triassic rocks in the Middle East: A Discussion

Lithofacies distribution of the Permian-Triassic rocks in the Middle East: A Discussion

Lithofacies, Diagenesis, and Porosity, Ivishak Sandstone, Prudhoe Bay Area, Alaska: ABSTRACT

End_Page 605------------------------------The Permo-Triassic Ivishak Sandstone is the main reservoir interval of the Prudhoe Bay field, North Slope, Alaska. Studies of cored sequences from the field and offshore (Reindeer Island) reveal that porosity development within the Ivishak Sandstone has a complex relationship dependent on both depositional (lithofacies) and postdepositional (diagenetic) history. These factors are related to the tectonic history of the basin. Five dominant lithofacies are identified: (1) interbedded very fine sandstones and mudstones, (2) parallel laminated carbonaceous fine sandstones, (3) multistory upward-fining medium sandstones, (4) conglomerates, and (5) multistory upward-fining coarse to granular sandstones. These lithofacies occur everywhere as upward-coarsening to conglomerate sequences. In the onshore (Prudhoe Bay field) area the coarsening sequence is overlain by a gross upward-fining sequence of gravelly to medium-grained multistory sandstones. This thins dramatically to the north, and is absent at Reindeer Island. Consideration of lithofacies and thickness variation leads to an interpretative model concerning evolution of the basin with respect to tectonics and sedimentation. Thus initial progradation of an ac ive alluvial fan-delta system from the northeast was replaced by progressive transgression from the south of more distal upon proximal facies. Petrographic characteristics of the rocks reveal that porosity development is intimately related to lithofacies. Porosity within the medium-grained sandstones is predominantly due to dissolution of early nodular calcite. Porosity within the conglomeratic intervals appears to be much more of a primary (textural) origin. Hypothetical porosity profiles can thus be constructed based on predicted lithofacies distribution across the area in any direction. End_of_Article - Last_Page 606------------

Lithofacies distribution of the Permian-Triassic rocks in the Middle East: A Reply

Lithofacies distribution of the Permian-Triassic rocks in the Middle East: A Reply

Palaeoclimate, sedimentation and continental accretion

Climate has a pervasive effect on sedimentation today, and the same climatic patterns are reflected in the distribution of lithofacies through the Palaeozoic, as the continents migrate beneath the climatic zones. The low-latitude hot wet zone is represented by thick elastics, coals and carbonates and is best developed along east coasts where prevailing winds bring moisture and heated surface waters toward the continent. The desert zones occur on the west sides of continents centred at 20° north and south, and these dry belts are represented in the geological record by evaporites. Tillites, thick elastics and coals occur in the temperate rainy belts, especially on the windward, west sides of continents above 40° latitude. Continental accretion occurs where subduction zones coincide with rainy zones, such that the products of erosion are transported to the trench, and thus thrust back, extending the margin of the continent. The opposite process of ‘tectonic erosion’, wherein the descending oceanic slab continually ‘rasps’ away the margin of the continental crust, may occur in areas where rainfall and surface run-off is insufficient to provide trench sediments. This process has been operating adjacent to the Atacama Desert in South America during the past 200 Ma. To judge by the eastward migration of the calc-alkaline intrusive foci, about 250 km of the margin of South America have been transported down the subduction zone during this period.

Genetic Lithostratigraphy of Dunkard Group, Southwestern Pennsylvania and Northern West Virginia: ABSTRACT

The Dunkard Group (Late Pennsylvanian-Early Permian) consists of 400 m of clastic sedimentary rocks with thin limestones and coals that were deposited in deltaic and alluvial-plain environments during the final stages of late Paleozoic sedimentation in the Appalachian basin. Lithofacies indicative of deposition in prograding, tidally influenced, high-constructive deltas dominate the lower Dunkard; these lithofacies are superseded up-section by alluvial-plain lithofacies. The distribution of lithofacies and paleocurrent data indicates that the fluival-deltaic systems prograded northward during deposition of the Dunkard. Sandstones of the Dunkard Group are typically multistory belt sands which were deposited by meandering rivers and highly sinuous delta distributaries. Petrographic analysis indicates that Dunkard sandstones are immature to submature litharenites derived from a mixed sedimentary, metasedimentary, and volcanic terrane, suggesting a collision orogene provenance related to Alleghenian suturing. Composition of the sandstones is strongly grain-size controlled and depositional environments influenced composition by controlling grain size. Constant composition through the section suggests no major change in source lithology or tectonic regime of the source area during Dunkard deposition. End_of_Article - Last_Page 960------------

Influence of Pore Geometry on Future Enhanced Recovery in Ordovician (Red River) Carbonate Reservoirs at Cabin Creek Field, Montana: ABSTRACT

This study related the distribution of pore geometry to enhanced recovery within the Upper Ordovician Red River End_Page 983------------------------------ Formation, Cabin Creek field, Montana. The field is located on the Cedar Creek anticline in southeast Montana. The Red River Formation is a sequence of alternating limestones and dolostones. Lateral and vertical variations of dolomitization are mostly responsible for reservoir heterogeneity. Production is from the U2, U4, and U6 dolostones, whereas the interstratified U1, U3, and U5 limestone units are nonproductive. Cumulative Ordovician and Silurian production was 61,574,000 bbl of oil as of September 1979, with reserves of 13,426,000 bbl. Waterflood began in 1964, and the field is a good candidate for tertiary recovery by the carbon dixoide miscible process. Studies of thin sections, mercury capillary pressure curves, and resin pore casts have shown that several different types of pore systems occur, each associated with a particular depositional environment and diagenetic regime. Pore-system geometry is a function of the size and shape of the dolomite crystals composing the reservoir rock matrix. The size, sorting, and shape of pore throats determine the reservoir characteristics of each pore system. In addition to dolomitization, post-depositional leaching of calcite and evaporitc sulfate minerals was important in reservoir porosity development. Mean pore-throat size, a statistical measure of pore geometry, was found to increase as porosity increased. Using this relation and electric log porosity values, it is possible to predict pore geometry and, as a consequence, recovery efficiency, if lithofacies distribution, porosity type, and diagenetic history are known. Since residual oil saturation is strongly dependent on the pore-system characteristics of the reservoir rock, it is possible to identify parts of the reservoir which have potentially high residual oil saturation, thus establishing targets for enhanced recovery. End_of_Article - Last_Page 984------------

Petroleum Geology of Southern Appalachian Foreland Basin: Black Warrior Basin of Alabama: ABSTRACT

Because much of the petroleum contained in giant structure traps in the United States has been discovered, the petroleum resources of the future will be from complex petroleum traps involving structure, lithofacies distribution, and diagenetic alteration. The Black Warrior basin of northwestern Alabama is an excellent basin to prospect for combination petroleum traps; to date 35 petroleum fields have been discovered. The key to successful prospecting in this basin involves the delineation of local structure and determination of reservoir size, morphology, and quality. Mississippian sandstone reservoirs presently have the greatest petroleum potential, the Carter and Lewis sandstones being the most economic of these reservoirs. The Carter was deposited as part of a high-con tructive, elongate to lobate delta which prograded from northwest to southeast into the basin. Specific deltaic environments identified include distributary channel and mouth bar, distal-bar, prodelta, and interdistributary bay. The Lewis accumulated as a series of elongate, northwest to southeast trending sand bodies on a shallow marine shelf. Specific environments identified include central-bar, interbar, and shelf. Carter distributary-mouth bar and distal-bar lithofacies and Lewis central-bar lithofacies constitute the primary Mississippian reservoirs in the basin. These sandstones are usually fine grained, well sorted, subangular to subrounded quartzarenites or sublitharenites. Primary interparticulate porosity has been reduced through the development of quartz overgrowths and/or calcite cementation. Porosity is principally secondary and involves leaching of carbonate allochems, calcite cement, and/or matrix. The Carter prodelta and interdistributary-bay shales and the Lewis marine shales make excellent petroleum source rocks. These shales contain amorphous, algal, and herbaceous kerogen. The state of alteration of the kerogen indicates that the thermal history of the basin has been favorable f r the generation and preservation of hydrocarbons. The hydrocarbon-trapping capabilities of these strata have been enhanced because of their association with normal faults. End_of_Article - Last_Page 1666------------