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At least 109 records · Page 6Linked to original sources
USGS2000

Sequence stratigraphy of the Aux Vases Sandstone: A major oil producer in the Illinois basin

The Aux Vases Sandstone (Mississippian) has contributed between 10 and 25% of all the oil produced in Illinois. The Aux Vases is not only an important oil reservoir but is also an important source of groundwater, quarrying stone, and fluorspar. Using sequence stratigraphy, a more accurate stratigraphic interpretation of this economically important formation can be discerned and thereby enable more effective exploration for the resources contained therein. Previous studies have assumed that the underlying Spar Mountain, Karnak, and Joppa formations interfingered with the Aux Vases, as did the overlying Renault Limestone. This study demonstrates that these formations instead are separated by sequence boundaries; therefore, they are not genetically related to each other. A result of this sequence stratigraphic approach is the identification of incised valleys, paleotopography, and potential new hydrocarbon reservoirs in the Spar Mountain and Aux Vases. In eastern Illinois, the Aux Vases is bounded by sequence boundaries with 20 ft (6 m) of relief. The Aux Vases oil reservoir facies was deposited as a tidally influenced siliciclastic wedge that prograded over underlying carbonate-rich sediments. The Aux Vases sedimentary succession consists of offshore sediment overlain by intertidal and supratidal sediments. Low-permeability shales and carbonates typically surround the Aux Vases reservoir sandstone and thereby form numerous bypassed compartments from which additional oil can be recovered. The potential for new significant oil fields within the Aux Vases is great, as is the potential for undrained reservoir compartments within existing Aux Vases fields.

Illinois↗
USGS2016

Reconnaissance stratigraphy of the Red Glacier Formation (Middle Jurassic) near Hungryman Creek, Cook Inlet basin, Alaska

Geochemical data suggest the source of oil in upper Cook Inlet fields is Middle Jurassic organic-rich shales in the Tuxedni Group (Magoon and Anders, 1992; Lillis and Stanley, 2011; LePain and others, 2012, 2013). Of the six formations in the group (Detterman, 1963), the basal Red Glacier Formation is the only unit that includes fine-grained rocks in outcrop that appear to be organic-rich (fig. 3-1). In an effort to better understand the stratigraphy and source-rock potential of the Red Glacier Formation, the Alaska Division of Geological & Geophysical Surveys, in collaboration with the Alaska Division of Oil and Gas and the U.S. Geological Survey, has been investigating the unit in outcrop between Tuxedni Bay and the type section at Lateral and Red glaciers (Stanley and others, 2013; LePain and Stanley, 2015; Helmold and others, 2016 [this volume]). Fieldwork in 2015 focused on a southeast-trending ridge south of Hungryman Creek, where the lower 60–70 percent of the formation (400–500 m) is exposed and accessible, except for the near-vertical faces of three segments near the southeast end of the ridge (figs. 3-2 and 3-3). Three stratigraphic sections were measured along the ridge to document facies and depositional environments (figs. 3-3 and 3-4). Steep terrain precluded study of the upper part of the formation exposed east of the ridge. This report includes a preliminary summary of findings from the 2015 field season.

Alaska↗
USGS2004

Influence of near-surface stratigraphy on coastal landslides at Sleeping Bear Dunes National Lakeshore, Lake Michigan, USA

Lake-level change and landslides are primary controls on the development of coastal environments along the coast of northeastern Lake Michigan. The late Quaternary geology of Sleeping Bear Dunes National Lakeshore was examined with high-resolution seismic reflection profiles, ground-penetrating radar (GPR), and boreholes. Based on sequence-stratigraphic principles, this study recognizes ten stratigraphic units and three major unconformities that were formed by late Pleistocene glaciation and postglacial lake-level changes. Locally high sediment supply, and reworking by two regressions and a transgression have produced a complex stratigraphy that is prone to episodic failure. In 1995, a large landslide deposited approximately 1 million m3 of sediment on the lake floor. The highly deformed landslide deposits, up to 18 m thick, extend 3-4 km offshore and unconformably overlie well-stratified glacial and lacustrine sediment. The landslide-prone bluff is underlain by channel-fill deposits that are oriented nearly perpendicular to the shoreline. The paleochannels are at least 10 m deep and 400 m wide and probably represent stream incision during a lake-level lowstand about 10.3 ka B.P. The channels filled with sediment during the subsequent transgression and lake-level highstand, which climaxed about 4.5 ka B.P. As lake level fell from the highstand, the formation of beach ridges and sand dunes sealed off the channel and isolated a small inland lake (Glen Lake), which lies 5 m above the level of Lake Michigan and may be a source of piped groundwater. Our hypothesis is that the paleochannels act as conduits for pore water flow, and thereby locally reduce soil strength and promote slope failure.

Michigan↗
USGS1995

Paleocene to Middle Miocene planktic foraminifera of the southwestern Salisbury Embayment, Virginia and Maryland: biostratigraphy, allostratigraphy, and sequence stratigraphy

The Paleocene to Middle Miocene sedimentary fill of the southwestern Salisbury Embayment contains a fragmental depositional record, interrupted by numerous local diastems and regional unconformities. Using planktic foraminiferal biostratigraphy, 15 unconformity-bounded depositional units have been identified, assigned to six formations and seven alloformations previously recognized in the embayment. The units correlate with second- and third-order sequences of the Exxon sequence stratigraphy model, and include transgressive and highstand systems tracts. Alloformation, formation, and sequence boundaries are marked by abrupt, scoured, burrowed, erosional surfaces, which display lag deposits, biostratigraphic gaps, and intense reworking of microfossils above and below the boundaries. Paleocene deposits represent the upper parts of upper Pleocene Biochronozones P4 and P5, and rest uncomformably on Cretaceous sedimentary beds of various ages (Maastrichtian to Albian). Lower Eocene deposits represent parts of Biochronozones P6 and P9. Middle Eocene strata represent mainly parts of Biochronozones P11, P12, and P14. Upper Eocene sediments include parts of Biochronozones P15, P16, and P17. Oligocene deposits encompass parts of Biochronozones. N4b to N7 undifferentiated, P21a, and, perhaps, N4a. Lower Miocene deposits encompass parts of Biochronozones N4b to N7 undifferentiated. Middle Miocene strata represent mainly parts of Biochronorones N8, N9, and N10. Nine plates of scanning electron micrographs illustrate the principal planktic foraminifera used to establish the biostratigraphic framework. Two new informal formine of Praeterenuitella praegemma Li, 1987, are introduced.

Journal of Foraminiferal Research↗
USGS2007

Northward extension of Carolina slate belt stratigraphy and structure, South-Central Virginia: Results from geologic mapping

Geologic mapping in south-central Virginia demonstrates that the stratigraphy and structure of the Carolina slate belt extend northward across a steep thermal gradient into upper amphibolite-facies correlative gneiss and schist. The Neoproterozoic greenschist-facies Hyco, Aaron, and Virgilina Formations were traced northward from their type localities near Virgilina, Virginia, along a simple, upright, northeast-trending isoclinal syncline. This syncline is called the Dryburg syncline and is a northern extension of the more complex Virgilina synclinorium. Progressively higher-grade equivalents of the Hyco and Aaron Formations were mapped northward along the axial trace of the refolded and westwardly-overturned Dryburg syncline through the Keysville and Green Bay 7.5-minute quadrangles, and across the northern end of the Carolina slate belt as interpreted on previous geologic maps. Hyco rocks, including felsic metatuff, metawacke, and amphibolite, become gneisses upgrade with areas of local anatexis and the segregation of granitic melt into leucosomes with biotite selvages. Phyllite of the Aaron Formation becomes garnet-bearing mica schist. Aaron Formation rocks disconformably overlie the primarily felsic volcanic and volcaniclastic rocks of the Hyco Formation as evidenced by repeated truncation of internal contacts within the Hyco on both limbs of the Dryburg syncline at the Aaron-Hyco contact. East-northeast-trending isograds, defined successively by the first appearance of garnet, then kyanite ?? staurolite in sufficiently aluminous rocks, are superposed on the stratigraphic units and synclinal structure at moderate to high angles to strike. The textural distinction between gneisses and identifiable sedimentary structures occurs near the kyanite ?? staurolite-in isograd. Development of the steep thermal gradient and regional penetrative fabric is interpreted to result from emplacement of the Goochland terrane adjacent to the northern end of the slate belt during Alleghanian orogenesis. This mapping study indicates that the Carolina slate belt does not terminate on the north against through-going faults or rest on higher-grade basement as previously suggested.

American Journal of Science↗
USGS1991

Seismic stratigraphy and structure of Prydz Bay, Antarctica: Implications from Leg 119 drilling

Prydz Bay is situated on the MacRobertson Land coast of East Antarctica at the seaward end of a 700-km-long transverse rift zone, the Lambert Rift. New and reprocessed seismic reflection data are combined with drilling results from five Leg 119 sites across Prydz Bay to study the regional stratigraphy and structure of the continental shelf and upper slope. Severe seismic multiples hamper interpretations, yet seven acoustic units separated by unconformities can be distinguished regionally. Only four units (sedimentary) have been drilled. More than 5 km of well- to poorly-stratified units beneath the inner shelf fill the northeast-trending Prydz Bay basin, which is related to, but separated from, the Lambert Graben. Basinal units overlie metamorphic basement (unit PS.5) and are continental nonmarine deposits of possible late Paleozoic to early Mesozoic age (unit PS.4, Site 740) and Early Cretaceous and younger(?) age (unit PS.2B, Site 741). Seaward, the basin is flanked by a buried and intruded(?) basement ridge (units PS.5 and PS.6). Continuous to distorted reflections cover the ridge and dip seaward in a prograding unit (unit PS.2A) beneath the outer shelf. Glaciomarine rocks of late Eocene to early Oligocene age comprise the innermost part of the unit PS.2A (Sites 742 and 739) and Holocene glacial rocks the outermost (Site 743); ages of intermediate parts of the unit are unknown. A flatlying unit of chaotic to continuous reflectors directly beneath the seafloor covers most of the northeast shelf (unit PS. 1, Sites 740, 741, 742, and 739), and is composed of compacted glacial diamictites of late Miocene and younger age. We suspect that significant rifting and glacial events have caused acoustic disconformities beneath Prydz Bay. The principal rifting events began with earliest rifting of Gondwana in late Paleozoic time (units PS.5 to PS.4) and culminated with continental breakup in Early Cretaceous time (units PS.4 to PS.2B). The advent of East Antarctic glaciation in late Eocene to early Oligocene time (units PS.2B to PS.2A) and the grounding of ice sheets across the shelf in midand late-Cenozoic times (unit PS.l to underlying units) created the principal glacial disconformities. The seaward-prograding glacial sequences beneath the outermost shelf record numerous post-early Oligocene glacial events and likely sea-level changes that can only be partially mapped with existing seismic and drilling data.

Conference Paper↗
USGS1997

Upper Eocene sequence stratigraphy and the Absecon Inlet Formation, New Jersey Coastal Plain

We evaluate the age, benthic biofacies, and sequence stratigraphy of thick and well-recovered upper Eocene sediments from the New Jersey Coastal Plain. These strata are herein defined as a lithostratigraphic unit and named the Absecon Inlet Formation. The formation is divided into upper and lower portions. At its type locality in the Atlantic City borehole, the lower portion of the Absecon Inlet Formation consists of 171 ft (52 m) of glauconitic silts and silty clays and is assigned to calcareous nannoplankton Zone NP 19/20 (late Eocene). At the ACGS#4 borehole, the type locality for its upper portion, the formation consists of slightly sandy clays and is assigned to Zone NP 21 (late Eocene to earliest Oligocene). The continuous stratigraphic occurrence of Hantkenina spp. in these sediments is evidence of an Eocene age for the upper portion of the Absecon Inlet Formation. Benthic foraminiferal analysis reveals five biofacies in the Absecon Inlet Formation, three of which can be related to paleowater depth: a Siphonina biofacies inhabited water depths of 75 ± 25 m; a Cibicidoides biofacies inhabited water depths of 100 ± 30 m; and a Globobulimina biofacies inhabited water depths of 125 ± 30 m. In addition, a Gyroidinoides biofacies occurs only within transgressive systems tracts. A Bulimina jacksonensis biofacies is believed to be related to a circum-Atlantic paleoceanographic event unrelated to depth changes on the shelf. Gamma-log, lithologic, and faunal/floral data are used to interpret the sequence stratigraphic architecture of the Absecon Inlet Formation. We conclude that the timing of unconformities (sequence boundaries) and maximum flooding surfaces within the Absecon Inlet Formation is consistent with the eustatic record of Exxon and the global δ 18 O record.

New Jersey↗
USGS1946

Summary of the Midway and Wilcox stratigraphy of Alabama and Mississippi

This study of the stratigraphy of the Midway and Wilcox groups of Alabama and Mississippi was part of the extensive bauxite investigations carried on by the Geological Survey and the Bureau of 'lines of the United States Department of the Interior in 19112 and 1943. The stratigraphic study was undertaken to determine in what formation or formations the bauxite deposits occur, under what paleogeographic conditions the bauxite-bearing formations were deposited, and when and under what conditions the bauxite was formed.

Alabama, Mississippi↗
USGS1947

Stratigraphy and structure of the area of the Kurupa, Oolamnagavik, Killik, and Colville Rivers

The area between 68° 3C' and 69° 08 N. latitude and between 154° and 155° 20 W. longitude was covered by U. S. Geological Survey party 4 during the period May 18 to September 2. Traverses were confined mainly to the valleys of the Kurupa, Oolamnagavik, and Colville Rivers inasmuch as very little rock is exposed in the interstream areas. This report is a compilation of the field data and of the results of office and laboratory work on rock specimens, fossils, and aerial photographs of the area. An interpretation of the structure and stratigraphy of this area is presented, and possible correlations with the Killik River area to the east are suggested. Some revisions of the conclusions in this report may become necessary in the light of further field work in adjacent areas and heavy mineral studies, but it is believed that any changes will not materially alter the geologic picture of the area.

Alaska↗
USGS1947

Preliminary report on stratigraphy and structure of the area of Kigalik and Awuna Rivers, Alaska

During the summer of. 1947, U. S. Geological Survey Party No. 2 made a reconnaissance survey of the area between Awuna River and the divide north of the Kigalik River. The westernmost observations were made along the Awuna anticline to longitude about 157°30' W. and along the Kigalik anticline to longitude about 156°55'W. The easternmost work was done along the Knife Blade Ridge anticline at a longitude of about 154°30'W. Not all of this area was traversed, but a general idea of the area studied may be had by noting the distribution of dip and strike symbols on Figure 1. Parts of this area had been previously visited by Smith 1/ in 1927 as a part of his traverse from Allakaket to the Arctic Coast. In the period from about July 10 to August 5 his party ascended the Awuna River and Birthday Creek, portaged over the Kigalik-Awuna divide at Birthday Pass, and descended the Kigalik River to its mouth. Various parties in the field season of 1946 worked in areas not far distant. Webber 2/ began his field work near the headwaters of the Meade River and measured a section across the Kigalik anticline about 25 miles beyond the westernmost observations made on that structure by Party No. 2. Work by Chapman and Thurrell 3/ along the Colville River parallels at a distance of three or four miles work by Party No. 2 in the vicinity of Knife Blade Ridge. The easternmost observations by Party No. 2 in the vicinity of Knife Blade Ridge are about 11 miles west of the area south of Maybe Creek mapped by Ray and Fischer.4/ Of the 1947 work of other field parties that of Thurrell 5/ along the Colville River is most closely related to this report. His thickness from the base of Zone A to his Trace No. 5 is included in Column 1 of Figure 3. Webber's work 6/ along the Ikpikpuk and Titaluk Rivers is also in a closely related area. Party No. 2 moved through this area by weasel, the weasels being used extensively on the daily traverses. The party assembled at Umiat late in May and was flown out to a lake about one mile west of the Ikpikpuk River at latitude 69°40' N. where the weasels and initial supplies had been previously cached. Early in June the party moved south into the area in which it was to begin work. For the next several weeks the party worked in the area north of the Kigalik River, moving westward along the divide north of that river. At this time considerable work was done south of the Kigalik River, west of longitude 154°40'W. No closure was detected along the Kigalik anticline. Shortly after the middle of July the party moved southwestward to the vicinity of the Awuna anticline where a westerly plunge had been suggested from the study of aerial photographs. The general route of the party from then on was eastward along the divide between the Awuna and Kigalik Rivers. Due to the need to reach a food cache further east very little data was gathered in the area between Birthday and Section Creeks. It was intended to work this area by one or two spike trips from the camp at the head of Section Creek. However, after constructing a cross-section from data gathered by the party along Section Creek and by Thurreli in the area between the Colville and Awuna Rivers it became apparent that the strata exposed along the axis of the Awuna anticline were stratigraphically below the base of Zone A. It thus appeared that there would be little point in attempting to gather additional data in the area between Birthday and Section Creeks. The party continued eastward, working along the south flank of the Kigalik anticline. On September 1, the party camped about one mile west of the summit of Knife Blade Ridge. Because of unfavorable weather at this time only a small amount of field work was accomplished in the next week. Enough data was gathered to give a general picture of the structure here, but the data on stratigraphy and structure is far from exhaustive. On September 9 the party moved eastward, camping that night about 3 miles northeast of :Wolf Creek, and arriving at Umiat on the afternoon of September 10. Aerial photographs were carried in the field and used to record the points at which observations were made. A considerable amount of data was recorded on the photographs. Approximate elevations were obtained, at first by aneroid barometers, and later by more sensitive airplane altimeters. Plane table and alidade were used in local traverses in the area north of the Kigalik River to obtain dips and strikes by the 'three-point method. Nearly all other dips and strikes recorded were measured by Brunton compass. Dips of 5° or less in the area south of the Kigalik River should, in general, be considered as dip components with only the approximate strike shown. These low dips were taken on bedding traces* where it was usually impossible to observe an accurate strike with the Brunton.

Alaska↗
USGS1947

Preliminary report on stratigraphy and structure of the area of the Colville River north of Umiat, Alaska

The stratigraphy and structure of the area of the Colville north of Umiat was studied by U. S. GeologicaI Survey Party No. 1 during the period of May 31 to July 19, 1947. The. party, consisting pf two geologists, a cook, and a "weasel" mechanic, left Umiat in two "weasels”. The weasels were used to transport the party and equipment from camp to camp, and also made it possible for the geologists to work as far as 15 to 20 miles out from a camp in one day. A ten-foot canvas-boat was carried along. During most of the month of June even the smaller tributaries to the Kogohokruk carried enough melt and run off water to make them navigable in the 10-foot boat. The party returned to Umiat on June 23, after traversing both the Kikiakrorak and the Kogohokruk Rivers, and several smaller tributaries to the Kogohokruk.

Alaska↗
USGS1950

Preliminary report on the stratigraphy and structure of part of the Carbon Creek and Ketik anticlines

U. S. Geological Survey Party No. 4 mapped the stratigraphy and structure of parts of the Carbon Creek and Ketik anticlines during the summer of 1950. The area, which lies in quadrangles I-19 and I-20 is shown in figure 1. Large-scale maps, compiled from plane-table surveys, give a more detailed picture of two parts of the area, the west plunge of the Carbon Creek anticline (fig. 2) and a segment near the middle of the Ketik anticline (fig. 3).

Alaska↗
USGS1946

Preliminary report on stratigraphy and structure of the Umiat anticline

During the summer of 1946 the United States Geological Survey, as part of its program of stratigraphic and structural investigations in the Naval Petroleum Reserve No. 4, had one field party investigating the Umiat area. The stratigraphy of the area was already fairly well known from earlier investigations. The main object of this investigation was to delineate, in as much detail as possible, the Umiat anticline in the are of Umiat Test No. 1. Outcrops in the Umiat area are few. Direct compass readings for strikes and dips of bedding cannot be trusted since cross-bedding. slumping, and frost-heaving are the rule rather than the exception. `structural data was obtained by use of a plane table and alidade by the three-point method. On the accompanying geologic map many of the strikes and dips shown were obtained by solving three-point problems. Additional structural data was obtained by mapping structural traces.*

Alaska↗
USGS2002

Stratigraphy of the Upper Cretaceous Mancos Shale (upper part) and Mesaverde Group in the southern part of the Uinta and Piceance basins, Utah and Colorado

Cross section A–A' was constructed in support of the oil and gas assessments of the Mesaverde and Mancos/Mowry Total Petroleum Systems in the Uinta and Piceance Basins of Utah and Colorado (fig. 1) (U.S. Geological Survey Uinta-Piceance Province Assessment Team, in press). This citation is referred to henceforth as simply “USGS, in press.” The Mesaverde Total Petroleum System contains continuous gas derived primarily from carbonaceous shale and coal in the Mesaverde Group [chapter by Johnson and Roberts in USGS (in press)]. The Mancos/Mowry Total Petroleum System contains continuous gas derived primarily from marine source rocks in the Mancos and Mowry Shales [chapter by Kirschbaum in USGS (in press)]. Cross section A–A' illustrates the stratigraphy of these Upper Cretaceous rocks, emphasizing the fluvial, coal-bearing coastal plain, nearshore marine, and offshore marine strata. The cross section is presented as a hard copy in this report and as a chapter by Hettinger and Kirschbaum (USGS, in press).

Colorado, Utah↗
USGS1981

Map showing paleontological control of Paleozoic stratigraphy in New England

Assignment of Phanerozoic stratigraphic units to their proper place in the geologica time scale is based primarily on paleontology. Radiometric methods are becoming increasingly important (Naylor, 1976), particularly where paleontological data are lacking. This map and text are concerned only with the paleontological data bearing on the Paleozoic stratigraphy of New England.

Miscellaneous Field Studies Map↗
USGS1983

Structure maps and seismic stratigraphy of the Yakataga segment of the continental margin, northern Gulf of Alaska

Multichannel seismic-reflection data show the late Cenozoic structure, seismic stratigraphy, and geologic history of the Yakataga segment of the continental margin, between Icy Bay and Kayak Island, northern Gulf of Alaska. The structure of the Yakataga segment consists of broad folds and associated thrust faults beneath the continental shelf and slope, trending generally northeast in the eastern part of the s~gment to east-west in the western part. Anticlines are generally asymmetric and doubly plunging and are commonly bounded on the seaward side by high-angle thrust faults. The degree of deformation is less intense than is observed in adjacent onshore areas. The age of deformation decreases seaward and the deformation shows an overall southeastward migration with time. Structures of similar age define three structural zones; structural growth was roughly contemporaneous in each structural zone, although the local growth pattern is complex in detail. Deformation within each structural zone was followed by subsidence and burial by rapidly deposited marine sediment. Deformation appears to have been continuous during the late Cenozoic, rather than a series of discrete events, because subsidence of a particular structural zone is accompanied by initiation of growth on a younger, more seaward zone. Varying degrees of reactivation of the older structures within recent time have resulted in renewed uplift of these structures. Average sedimentation, uplift, and subsidence rates are all extremely high, and generally range from about 1 to 2 m/1,000 yr; these rates can locally be much higher. The average strike of structures in the Yakataga segment indicates northwest-southeastward compression and is consistent with the current convergence direction between the Pacific and North America plates. Observed shortening within the segment is much less than required by the late Cenozoic convergence rate (about 6 cm/yr), and the major deformation is taken up elsewhere, primarily onshore. Thus, the deformation of the Yakataga segment is caused by minor shortening of the continental margin between Cross Sound and Kayak Island, which together comprise the Yakutat block, as the margin moves northwestward with the Pacific plate and collides with the North America plate.

Alaska↗
USGS1985

Map showing Tertiary stratigraphy and structure of the Northern San Joaquin Valley, California

This report is a result of recent studies of the Cenozoic stratigraphy and structure of the San Joaquin Valley that were directed at Cenozoic depositional and tectonic history. Most previous work on the Cenozoic has focused on the Quaternary surficial deposits and on the outcrops of older rocks at the margins of the valley, although ground-water resource studies of the upper Cenozoic deposits have used subsurface information (for example, Davis and others, 1959; Croft, 1972). One purpose of this report is to show the distribution and stratigraphic relations of Tertiary units under the valley and represents, in part, an attempt to extend correlations from Tertiary units previously recognized in outcrop at the margins of the valley into the subsurface. A second purpose is to depict the structure of the Tertiary rocks by cross sections and by a structure contour map of a middle Tertiary horizon. The emphasis in this report is on the Tertiary rocks of the northern part of the San Joaquin Valley, although pre-Tertiary stratigraphic units are shown on the cross sections where information was available. They serve to emphasize the discordance between the Neogene and the older units. Correlations of units in the Great Valley sequence (Late Jurassic to earliest Tertiary) are based mostly, with some modification, on the work of Hoffman (1964) and Callaway (1964), although the informal stratigraphic names used by those workers are not applied here.

California↗