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Sample records for formation upper cretaceous

  1. Outer shelf storm deposits of Upper Cretaceous Chico Formation, California

    SciTech Connect

    Russell, J.S.

    1987-05-01

    The Kingsley Cave member of the Upper Cretaceous Chico Formation, northeastern Sacramento Valley, California, is an outer shelf sequence consisting of muddy siltstones deposited below storm wave base. Silty fine-grained sandstone interbeds, interpreted as distal tempestites, are common within this member and are typically parallel laminated and devoid of shell material. Fossil concentrations within this member are rare, occurring as internally simple lenses within fine-grained sandstone interbeds. These fossil concentrations are up to 1.0 m in thickness. The faunas within these lenses are allochthonous or, less commonly, parautochthonous. Comparisons of the faunas in these shell lenses with published faunal assemblages for the Chico Formation and other Upper Cretaceous west coast nearshore deposits indicate that they were displaced from shallower-water environments. Lenses typically contain faunal elements of shoreface and inner shelf environments, which were located to the east during this time, as well as outer shelf faunal elements. These fossil concentrations are sedimentologic in origin. The scoured bases and overlying hummocky cross-stratified to ripple laminated siltstones of these lenses, their relative thicknesses, and the allochthonous shallower-water faunal elements contained within them are all characteristics of proximal tempestites, normally found within inner shelf sandstones. Distal tempestites, typical of outer shelf facies, are the norm for the Kingsley Cave member, while these proximal tempestites are the exception. The former were deposited by normal-strength storm events, while the latter are indicative of rare, extremely high-intensity storm events. During these extremely high-intensity storms proximality trends shifted seaward (westward), causing proximal tempestites to form more offshore than the proximal tempestites generated by normal-strength storms.

  2. Stratigraphic relations and U-Pb geochronology of the Upper Cretaceous upper McCoy Mountains Formation, southwestern Arizona

    USGS Publications Warehouse

    Tosdal, R.M.; Stone, P.

    1994-01-01

    A previously unrecognized angular unconformity divides the Jurassic and Cretaceous McCoy Mountains Formation into a lower and an upper unit in the Dome Rock Mountains and Livingston Hills of western Arizona. The intraformation unconformity in the McCoy Mountains Formation developed where rocks of the lower unit were deformed adjacent to the southern margin of the Maria fold and thrust belt. The upper unit of the formation is interpreted as a foreland-basin deposit that was shed southward from the actively rising and deforming fold and thrust belt. The apparent absence of an equivalent unconformity in the McCoy Mountains Formation in adjacent California is presumably a consequence of the observed westward divergence of the outcrop belt from the fold and thrust belt. Tectonic burial beneath the north-vergent Mule Mountains thrust system in the latest Late Cretaceous (~70 Ma) marked the end of Mesozoic contractile deformation in the area. -from Authors

  3. Variations in vitrinite reflectance values for the Upper Cretaceous Mesaverde Formation, southeastern Piceance basin, northwestern Colorado

    SciTech Connect

    Nuccio, V.F.; Johnson, R.C.; Johnson, S.Y.

    1989-01-01

    The authors discuss how most of the Upper Cretaceous Mesaverde Formation in the southeastern Piceance basin is thermally mature enough to have produced hydrocarbons by thermal generation, but only part of the Mesaverde is thermally mature enough to have expelled significant amounts of natural gas. The Early Permian( ) Fryingpan Member of the Maroon Formation consists of quartz-rich, very fine to fine-grained sandstone deposited in eolian dune and interdune environments. The Fryingpan Member (formerly called the sandstone of the Fryingpan River) is removed from the State Bridge Formation and assigned to the Maroon Formation.

  4. Biostratigraphic data from Upper Cretaceous formations-eastern Wyoming, central Colorado, and northeastern New Mexico

    USGS Publications Warehouse

    Merewether, E.A.; Cobban, W.A.; Obradovich, J.D.

    2011-01-01

    Lithological and paleontological studies of outcrops of Upper Cretaceous formations were conducted at 12 localities in eastern Wyoming, central Colorado, and northeastern New Mexico. The sequence extends upward from the top of the Mowry Shale, or age-equivalent rocks, through the Graneros Shale, Greenhorn Limestone, Carlile Shale, Niobrara Formation, Pierre Shale, and Fox Hills Sandstone, or age-equivalent formations, to the top of the Laramie Formation, or laterally equivalent formations. The strata are mainly siliciclastic and calcareous, with thicknesses ranging from about 3,300 ft in northeastern New Mexico to as much as 13,500 ft in eastern Wyoming. Deposition was mainly in marine environments and molluscan fossils of Cenomanian through Maastrichtian ages are common. Radiometric ages were determined from beds of bentonite that are associated with fossil zones. The Upper Cretaceous formations at the 12 study localities are herein divided into three informal time-stratigraphic units based on fossil content and contact relations with adjacent strata. The basal unit in most places extends from the base of the Graneros to the top of the Niobrara, generally to the horizon of the fossil Scaphites hippocrepis, and spans a period of about 14 million years. The middle unit generally extends from the top of the Niobrara to the approximate middle of the Pierre, the horizon of the fossil Baculites gregoryensis, and represents a period of about 5 million years. The upper unit includes strata between the middle of the Pierre and the top of the Upper Cretaceous Series, which is the top of the Laramie Formation or of laterally equivalent formations; it represents a period of deposition of as much as 11 million years. Comparisons of the collections of fossils from each outcrop with the complete sequence of Upper Cretaceous index fossils can indicate disconformable contacts and lacunae. Widespread disconformities have been found within the Carlile Shale and between the Carlile

  5. Nonmarine upper cretaceous rocks, Cook Inlet, Alaska

    SciTech Connect

    Magoon, L.B.; Griesbach, F.B.; Egbert, R.M.

    1980-08-01

    A section of Upper Cretaceous (Maestrichtian) nonmarine sandstone, conglomerate, and siltstone with associated coal is exposed near Saddle mountain on the northwest flank of Cook Inlet basin, the only known surface exposure of nonmarine Upper Cretaceous rocks in the Cook Inlet area. The section, at least 83.3 m thick, unconformably overlies the Upper Jurassic Naknek Formation and is unconformably overlain by the lower Tertiary West Foreland Formation. These upper Cretaceous rocks correlate lithologically with the second or deeper interval of nonmarine Upper Cretaceous rocks penetrated in the lower Cook Inlet COST 1 well.

  6. The Sunny Point Formation: a new Upper Cretaceous subsurface unit in the Carolina Coastal Plain

    USGS Publications Warehouse

    Balson, Audra E.; Self-Trail, Jean; Terry, Dennis O.

    2013-01-01

    This paper formally defines the Sunny Point Formation, a new Upper Cretaceous subsurface unit confined to the outer Atlantic Coastal Plain of North and South Carolina. Its type section is established in corehole NH-C-1-2001 (Kure Beach) from New Hanover County, North Carolina. The Sunny Point Formation consists of light-olive-gray to greenish-gray, fine to coarse micaceous sands and light-olive-brown and grayish-red silty, sandy clays. The clay-rich sections typically include ironstone, lignitized wood, root traces, hematite concretions, goethite, limonite, and sphaerosiderites. The Sunny Point Formation is also documented in cores from Bladen County, North Carolina, and from Dorchester and Horry Counties, South Carolina. Previously, strata of the Sunny Point Formation had been incorrectly assigned to the Cape Fear and Middendorf Formations. The Sunny Point occupies a stratigraphic position above the Cenomanian marine Clubhouse Formation and below an upper Turonian unnamed marine unit. Contacts between these units are sharp and unconformable. Calcareous nannofossil and palynomorph analyses indicate that the Sunny Point Formation is Turonian.

  7. Biological markers in bitumens and pyrolyzates of Upper Cretaceous bituminous chalks from the Ghareb Formation (Israel)

    NASA Astrophysics Data System (ADS)

    Rullkötter, Jürgen; Aizenshtat, Zeev; Spiro, Baruch

    1984-01-01

    The sterane and triterpane distributions of three bituminous chalks from the Upper Cretaceous Ghareb Formation (Israel) were investigated both in the original extractable bitumens and in extracts obtained after pyrolysis of whole rock and isolated kerogen samples at 450°C. Pyrolysis was performed in a closed system under hydrous (whole rock) and anhydrous conditions (isolated kerogens). The carbon number distributions of steranes and triterpanes differ significantly between original bitumen and pyrolyzates. Unlike the bitumens in which diasteranes were not detected, the anhydrous pyrolyzates contain small amounts of diasteranes. The presence of water during pyrolysis leads to an increase of sterane isomerization, the abundant formation of diasteranes and an increase of the 18α( H)- trisnorneohopane/17α( H)- trisnorhopane ratio. Sterane isomerization maturation parameters show a closer match between original bitumen and pyrolyzates after pyrolysis in a closed system when compared with an open system.

  8. Reworking of Cretaceous dinosaurs into Paleocene channel deposits, upper Hell Creek Formation, Montana

    SciTech Connect

    Lofgren, D.L. ); Hotton, C.L. ); Runkel, A.C. )

    1990-09-01

    Dinosaur teeth from Paleocene channel fills have been interpreted as indicating dinosaur survival into the Paleocene. However, enormous potential for reworking exists because these records are restricted to large channel fills that are deeply incised into Cretaceous strata. Identification of reworked fossils is usually equivocal. This problem is illustrated by the Black Spring Coulee channel fill, a dinosaur-bearing Paleocene deposit in the upper Hell Creek Formation of eastern Montana. In this example, the reworked nature of well-preserved dinosaur bones is apparent only after detailed sedimentological and palynological analysis. Because of the potential for reworking, dinosaur remains derived from Paleocene fluvial deposits should not be assigned a Paleocene age unless the (1) are found in floodplain deposits, (2) are articulated, (3) are in channels that do not incise Cretaceous strata, or (4) are demonstrably reworked from Paleocene deposits. To date, reports of Paleocene dinosaurs do not fulfill any of these criteria. Thus, the proposal that dinosaurs persisted into the Paleocene remains unsubstantiated.

  9. Tectono-sedimentary framework of the early Cretaceous continental Bima formation (upper Benue Trough, NE Nigeria)

    NASA Astrophysics Data System (ADS)

    Guiraud, M.

    The major structural features of the upper Benue Trough, directly influenced by the Precambrian framework, were initiated during Early Cretaceous times. Previous studies have shown the sandy Bima member deposits to be of probable Neocomian to Upper Aptain age. The Lower Bima gfang lomerates are restricted to the faulted basin margins and give way to braided-river deposits and ≪lacustrine≫deposits towards the basin axes. Characteristic sedimentary profiles of the different facies present within the various Bima members are given. On a regional scale, a horst and graben structural environment controlled both Upper Jurassic to Neocomian magmatism and the overall paleocurrent pattern prevailing during Lower Bima member sedimentation. The Lower Bima continental detrital deposits were transported along varying directions from uplifted areas towards neighbouring sub-basins. These observations clearly demonstrate the influence of Early Cretaceous synsedimentary tectonics on Lower Bima deposition. Both the Benue and Chad structural trends were of importance in controlling the Early Cretaceous history of the Upper Benue basin. A detailed microtectonic study was carried out along the Early Cretaceous synsedimentary fault zones. The results obtained, coupled with those from regional tectonics, indicate that the Upper Benue trough consists of a set a Earlt Cretaceous rhomb grabens or pull-ampart basins with sinistral strike-slip borders trending N 40°E to N 70°E ("Benue" trend) and normal borders striking N 120°E to N 160°E ("Chad" trend). The sediments of the lower Bima member were deposited prior to a major regional hiatus corresponding to the levelling of the continental basins during Late Aptian to Albian times. The fine-grained sediments of the upper Bima member were deposited in an homogeneous braided river system flowing towards the northwest. These deposits seal the major Early Cretaceous structural features.

  10. Facies stratigraphy and relative sea-level history - Upper Cretaceous Eutaw formation, central and eastern Alabama

    SciTech Connect

    King, D.T. Jr. )

    1990-09-01

    The Upper Cretaceous (late Santonian-early Campanian) Eutaw Formation crops out in an east west-striking belt in the inner Coastal Plain of Alabama. Facies arrangement within the Eutaw indicates a regional paleoshoreline having depositional strike approximately parallel to and coincident with the present outcrop belt. The Eutaw Formation (40 to 120 m thick) rests disconformably on incised valleys (a type 1 unconformity) occurring at the top of the underlying Cenomanian-early Turonian nonmarine Tuscaloosa Formation. The Eutaw is topped by an erosional discontinuity that has slight relief and a discontinuous conglomeratic lag. In the outcrop and shallow subsurface, the Eutaw Formation has four main paralic and nearshore facies that are arranged in two discontinuity-bounded genetic packages of facies (or parasequences) both of which developed in a single eustatic cycle. The Eutaw facies are: carbonaceous and ostried-rich clayey silts (= back barrier); planar, trough, and low-angle cross-bedded medium-fine sands (= barrier island); fossiliferous bioturbated fine sands (= lower shoreface); and calcareous clays, silts, and sands (= inner shelf). The lower genetic package of the Eutaw Formation is bounded below by the tuscaloosa disconformity (a flooding surface) and is bounded above by a low-relief intraformational facies discontinuity. The intraformational facies discontinuity is likely a parasequence boundary developed at maximum eustatic high-stand in latest Santonian. The lower genetic package is mainly a transgressive sequence of back-barrier, barrier-island, lower-shoreface, and inner-shelf facies. The upper genetic package is mainly a progradational sequence encompassing the same set of facies as the lower genetic package.

  11. Facies architecture and depositional environments of the Upper Cretaceous Kaiparowits Formation, southern Utah

    NASA Astrophysics Data System (ADS)

    Roberts, Eric M.

    2007-04-01

    The Kaiparowits Formation is an unusually thick package of Upper Cretaceous (late Campanian) strata exposed in Grand Staircase-Escalante National Monument of southern Utah, USA. The formation was deposited within the rapidly subsiding Cordilleran foreland basin as part of a thick clastic wedge derived from sources in the Sevier orogenic belt, thrust sheets in southeastern Nevada and southern California, and the Mogollon slope in southwestern Arizona. Channel systems in the Kaiparowits Formation shifted from northeastward to southeastward flow over time, and for a short period of time, sea level rise in the Western Interior Seaway resulted in tidally influenced rivers and/or estuarine systems. Thick floodbasin pond deposits, large suspended-load channels, and poorly developed, hydromorphic paleosols dominate the sedimentary record, and all are suggestive of a relatively wet, subhumid alluvial system. This is supported by extremely rapid sediment accumulation rates (41 cm/ka), and high diversity and abundance of aquatic vertebrate and invertebrate fossils. Facies and architectural analysis was performed on the Kaiparowits Formation, resulting in the identification of nine distinct facies associations: 1) intraformational conglomerate, 2) mollusc-shell conglomerate, 3) major tabular sandstone, 4) major lenticular sandstone, 5) minor tabular and lenticular sandstone, 6) finely laminated, calcareous siltstone, 7) inclined heterolithic sandstone and mudstone, 8) sandy mudstone, and 9) carbonaceous mudstone. These facies associations are interpreted as: 1) channel lags, 2) rare channel-hosted storm beds, 3) meandering channels, 4) anastomosing channels, 5) crevasse splays and crevasse channels, 6) lakes, 7) tidally influenced fluvial and/or estuarine channels, 8) mud-dominated floodplains, and 9) swamps and oxbow lakes. Based on this analysis, the formation is subdivided into three informal units, representative of gross changes in alluvial architecture, including facies

  12. Upper Cretaceous (Campanian) phosphorites in Jordan: implications for the formation of a south Tethyan phosphorite giant

    NASA Astrophysics Data System (ADS)

    Pufahl, Peir K.; Grimm, Kurt A.; Abed, Abdulkader M.; Sadaqah, Rushdi M. Y.

    2003-10-01

    A record of sedimentary, authigenic, and biological processes are preserved within the Upper Cretaceous (Campanian) Alhisa Phosphorite Formation (AP) in central and northern Jordan. The AP formed near the eastern extremity of the south Tethyan Phosphorite Province (STPP), a carbonate-dominated Upper Cretaceous to Eocene "phosphorite giant" that extends from Colombia, North Africa to the Middle East. Multidisciplinary research of the AP and associated cherts, chalks, and oyster buildups indicate that phosphatic strata formed on a highly productive, storm-dominated, east-west trending epeiric platform along the south Tethyan margin. The onset of phosphogenesis and the accumulation of economic phosphorite coincided with a rise in relative sea level that onlapped peritidal carbonates of the Ajlun Group. Pristine phosphates are associated with well-developed micrite concretionary horizons and contain abundant non-keeled spiral planktic foraminifera and a low diversity benthic assemblage of Buliminacean foraminifera, suggesting that pristine phosphates are a condensed facies and phosphogenesis was stimulated by the effects of a highly productive surface ocean and the suboxic diagenesis of sedimentary organic matter. The bulk sediment composition and absence of Fe-bearing authigenic phases such as glauconite, pyrite (including pyrite molds), siderite, and goethite within pristine phosphates suggests that deposition and authigenesis occurred under conditions of detrital starvation and that "iron-pumping" played a minimal role in phosphogenesis. Authigenic precipitation of phosphate occurred in a broad array of sedimentary environments—herein termed a "phosphorite nursery"—that spanned the entire platform. This is a non-uniformitarian phenomenon reflecting precipitation of sedimentary apatite across a wide depositional spectrum in a variety of depositional settings, wherever the conditions were suitable for phosphogenesis. Sedimentologic data indicate that pristine

  13. Sulphur isotope geochemistry of pyrite from the Upper Cretaceous Marshybank Formation, Western Interior Basin

    NASA Astrophysics Data System (ADS)

    McKay, J. L.; Longstaffe, F. J.

    2003-04-01

    Variations in the texture and sulphur isotopic composition of pyrite in the Upper Cretaceous Marshybank Formation are linked to depositional environment. Abundant, framboidal (and lesser euhedral) pyrite precipitated in offshore marine rocks. Moderate quantities of pyrite also crystallized in brackish, coastal plain rocks. However, in contrast to marine pyrite, coastal plain pyrite is dominantly euhedral in texture, reflecting direct precipitation from a porewater with a relatively low dissolved sulphide concentration. In the marine rocks, pyrite δ34S values range from -35.7‰ to +27.4‰ (avg. -4.8‰ Canyon Diablo Troilite, CDT). Pyrite within carbonate concretions hosted in these marine rocks has a similar isotopic composition (-49.8‰ to +10.6‰ CDT). However, isotopic values are often highly variable within individual concretions as a result of the heterogeneous nature of sulphate reduction and pyrite formation within marine sediments. Pyrite in coastal plain rocks is characterized by relatively high δ34S values (-4.2‰ to +35.5‰, avg. +13.2‰ CDT), while the overlying sideritized conglomerates have the lowest δ34S values reported for Cretaceous rocks from the Western Interior Basin of North America (-49.8‰ to -41.7‰ CDT). Very low δ34S values, which are only observed in the marine rocks, are indicative of microbial sulphate reduction and pyrite formation in a sulphate-replete (i.e., open) system. Higher δ34S values (up to +18‰), which were obtained for both the marine and coastal plain rocks, are indicative of progressive pyrite crystallization in a sulphate-limited (i.e., closed) system. Such conditions are expected in marine sediments as burial occurs, and in brackish (i.e., low sulphate) sediments. Pyrite with very high δ34S values (>+18‰) is common in the coastal plain rocks. These high values are the result of influx of 34S-enriched, residual sulphide derived from overlying marine units. A minor amount of 34S-enriched pyrite is also

  14. Geochemical evaluation of upper cretaceous fruitland formation coals, San Juan Basin, New Mexico and Colorado

    USGS Publications Warehouse

    Michael, G.E.; Anders, D.E.; Law, B.E.

    1993-01-01

    Geochemical analyses of coal samples from the Upper Cretaceous Fruitland Formation in the San Juan Basin of New Mexico and Colorado were used to determine thermal maturity, type of kerogen, and hydrocarbon generation potential. Mean random vitrinite reflectance (%Rm) of the Fruitland coal ranges from 0.42 to 1.54%. Rock-Eval pyrolysis data and saturated to aromatic hydrocarbon ratio indicate that the onset of thermal hydrocarbon generation begins at about 0.60% Rm and peak generation occurs at about 0.85% Rm. Several samples have hydrogen index values between 200 and 400, indicating some potential for liquid hydrocarbon generation and a mixed Type III and II kerogen. Pentacyclic and tricyclic terpanes, steranes, aromatic steroids and methylphenanthrene maturity parameters were observed through the complete range of thermal maturity in the Fruitland coals. Aromatic pentacyclic terpanes, similar to those found in brown coals of Australia, were observed in low maturity samples, but not found above 0.80% Rm. N-alkane depleted coal samples, which occur at a thermal maturity of approx. 0.90% Rm, paralleling peak hydrocarbon generation, are fairly widespread throughout the basin. Depletion of n-alkanes in these samples may be due to gas solution stripping and migration fromthe coal seams coincident with the development of pressure induced fracturing due to hydrocarbon generation; however, biodegradation may also effect these samples. ?? 1993.

  15. Upper campanian (upper cretaceous) ammonites from the Marshalltown Formation-Mount laurel boundary beds in Delaware

    USGS Publications Warehouse

    Kennedy, W.J.; Cobban, W.A.

    1997-01-01

    New collections from the Marshalltown Formation and basal Mount Laurel Sand along the Chesapeake and Delaware Canal in Delaware clarify the ammonite dating of the interval. The Marshalltown Formation yields Pachydiscus (Pachydiscus) sp., Menuites portlocki (Sharpe, 1855) complexus (Hall and Meek, 1856), a subspecies restricted to the Baculites gregoryensis and Baculites scotti zones in the Western Interior of the United States, and Didymoceras binodosum (Kennedy and Cobban, 1993a) known only from the B. scotti zone of the Western Interior and correlatives in Arkansas and Texas. The basal part of the Mount Laurel Sand contains a complex assemblage preserved as phosphatic molds: Nostoceras (Nostoceras) monotuberculatum Kennedy and Cobban, 1993a, Nostoceras (N.) sp., Didymoceras platycostatum (Kennedy and Cobban, 1993b), D. stevensoni (Whitfield, 1877) (previously thought to be from the Marshalltown) and Exiteloceras jenneyi (Whitfield, 1877). The last two are index species of their eponymous zones in the Western Interior. This sequence is compatible with ammonites from the Wenonah Formation, which lies between the Marshalltown and Mount Laurel to the north and contains ammonites indicative of the Baculites scotti zone, and the fauna from higher in the Mount Laurel Sand, which includes elements of the Didymoceras cheyennense and Baculites compressus zones of the Western Interior sequence.

  16. Paleomagnetic results from the Upper Cretaceous Maudlow and Livingston formations, southwest Montana

    NASA Astrophysics Data System (ADS)

    Swenson, Paul; McWilliams, Michael

    1989-07-01

    A paleomagnetic investigation of welded tuff units from the Late Cretaceous Livingston and Maudlow Formations was undertaken to refine the Late Cretaceous to Paleocene APWP for cratonic North America. After progressive AF and thermal demagnetization, the Maudlow Formation (46.1°N, 248.9°E) yields a paleomagnetic pole at 70°N, 208°E (11 sites, A95 = 9°, K = 22). Tectonic correction improves the directional grouping, and the change is statistically significant. Two normal polarity intervals bounding a single reversed polarity interval are present. We interpret the reversed interval to be Chron 33r, on the basis of: [1] stratigraphic correlation of the Maudlow Formation with the Campanian Sedan Formation located 40 km to the east, and [2] K-Ar dates of 83 ± 2 Ma at the middle of the sampled section and 74.9 ± 1 Ma near the top of the sampled section. The Livingston Formation (45.5°N, 250.1°E) yields a high Hc magnetization with a negative fold test, suggesting a post-folding secondary magnetization. The Livingston mean direction yields a paleomagnetic pole at 72°N, 218°E (10 sites, A95 = 4°, K = 107) and is clearly distinguishable from a co-existing lower Hc component reflecting a recent viscous overprint. We interpret the high Hc magnetization as Late Cretaceous to Paleocene in age. Neither the Maudlow Formation pole nor the pole derived from the high Hc overprint in the Livingston Formation agree with previously published poles for either the Late Cretaceous or Tertiary, but they do lie on a simple continuation of the APWP between Late Cretaceous and Paleocene mean poles. Secondary magnetizations found in the Franciscan Complex of California also yield poles which lie on a proposed extension of the APWP. If the Franciscan secondary poles represent an overprint event associated with early Tertiary accretion, and if the Livingston secondary pole represents a deformational event related to Laramide uplift of the nearby Beartooth Range, then together these

  17. Preliminary stratigraphy and facies analysis of the Upper Cretaceous Kaguyak Formation, including a brief summary of newly discovered oil stain, upper Alaska Peninsula

    USGS Publications Warehouse

    Wartes, Marwan A.; Decker, Paul L.; Stanley, Richard G.; Herriott, Trystan M.; Helmold, Kenneth P.; Gillis, Robert J.

    2013-01-01

    The Alaska Division of Geological and Geophysical Surveys has an ongoing program aimed at evaluating the Mesozoic forearc stratigraphy, structure, and petroleum systems of lower Cook Inlet. Most of our field studies have focused on the Jurassic component of the petroleum system (this report). However, in late July and early August of 2012, we initiated a study of the stratigraphy and reservoir potential of the Upper Cretaceous Kaguyak Formation. The Kaguyak Formation is locally well exposed on the upper Alaska Peninsula (fig. 25) and was named by Keller and Reiser (1959) for a sequence of interbedded siltstone and sandstone of upper Campanian to Maastrichtian age that they estimated to be 1,450 m thick.Subsequent work by Detterman and Miller (1985) examined 900 m of section and interpreted the unit as the record of a prograding submarine fan.This interpretation of deep-water deposition contrasts with other Upper Cretaceous rocks exposed along the Alaska Peninsula and lower Cook Inlet that are generally described as nonmarine to shallow marine (Detterman and others, 1996; LePain and others, 2012).Based on foraminifera and palynomorphs from the COST No. 1 well, Magoon (1986) concluded that the Upper Cretaceous rocks were deposited in a variety of water depths and environments ranging from upper bathyal to nonmarine. During our recent fieldwork west and south of Fourpeaked Mountain, we similarly encountered markedly varying lithofacies in the Kaguyak Formation (fig. 25), and we also found oil-stained rocks that are consistent with the existence of an active petroleum system in Upper Cretaceous rocks on the upper Alaska Peninsula and in lower Cook Inlet. These field observations are summarized below.

  18. Coal resources of Upper Cretaceous Fruitland Formation in the Southern Ute Indian Reservation, southwestern Colorado

    USGS Publications Warehouse

    Sandberg, Dorothy T.

    1990-01-01

    Coal resources of the Upper Cretaceous Fruitland Formation in the Southern Ute Indian Reservation are estimated to total 16 billion short tons of bituminous coal in beds 2 feet thick or more. The coal-bearing Fruitland Formation underlies about 700 square miles of the Southern Ute Indian Reservation and crops out in a roughly semicircular band around the northern edge of the structural San Juan Basin. The coal beds locally dip more than 10? to the southeast along the northwestern rim of the basin. This estimate of coal resources is based on a study of about 500 geophysical logs, mostly of oil and gas wells. Total coal resources include 15 billion short tons of identified resources, based on data points 3 miles or less apart, and about 1 billion short tons of undiscovered or hypothetical resources, based on data points more than 3 miles apart. In this report, the coal-bearing interval is divided into three overlapping zones: lower, middle, and upper. Coal resources were estimated by aggregate thickness for each zone. The lower zone, which is southwest of a large stratigraphic rise of the Pictured Cliffs Sandstone, contains the thickest coal beds, generally in two thick beds that locally have an aggregate thickness as much as 50 feet. The lower zone contains about 28 percent of the estimated resources; in the lower zone, 6 percent of the resources are less than 500 feet beneath the surface, 10 percent of the resources are 500-2,000 feet beneath the surface, and 84 percent are more than 2,000 feet beneath the surface. The middle zone contains 22 percent of the estimated resources; in the middle zone, only 2 percent of the resources are less than 500 feet beneath the surface, 4 percent of the resources are 500-2,000 feet beneath the surface, and 94 percent are more than 2,000 feet beneath the surface. The upper zone contains about half the estimated resources, in part because it occupies about three-fourths of the area underlain by the Fruitland Formation; in the upper

  19. Paleomagnetic results from the Upper Cretaceous Maudlow and Livingston Formations, southwest Montana

    SciTech Connect

    Swenson, P.; McWilliams, M. )

    1989-07-01

    A paleomagnetic investigation of welded tuff units was undertaken to refine the Late Cretaceous to Paleocene apparent polar wander path (APWP) for cratonic North America. The Maudlow Formation yields a paleomagnetic pole at 70{degree}N, 208{degree}E. Tectonic correction improves the directional grouping. Two normal polarity intervals bounding a single reversed polarity interval are present. The authors interpret the reversed interval to be Chron 33r, on the basis of: (1) stratigraphic correlation of the Maudlow Formation with the Campanian Sedan Formation located 40 km to the east, and (2) K-Ar dates of 83 {plus minus} 2 Ma at the middle of the sampled section and 74.9 {plus minus} 1 Ma near the top of the sampled section. The Livingston Formation yields a high H{sub c} magnetization with a negative fold test, suggesting a post-folding secondary magnetization. The Livingston mean direction yields a paleomagnetic pole at 72{degree}N, 218{degree}E. Neither the Maudlow Formation pole nor the pole derived from the Livingston Formation agree with previously published poles for either the Late Cretaceous or Tertiary but they do lie on a simple continuation of the APWP between Late Cretaceous and Paleocene mean poles. Secondary magnetizations found in the Franciscan Complex of California also yield poles which lie on a proposed extension of the APWP. If the Franciscan secondary poles represent an overprint event associated with early Tertiary accretion, and if the Livingston secondary pole represents a deformational event related to Laramide uplift of the nearby Beartooth Range, then together these poles suggest that the North American APWP may continue farther to the east and south to define a Cretaceous-Tertiary cusp.

  20. Upper Cretaceous Paleocene biostratigraphy and magnetostratigraphy, Hell Creek and Tullock Formations, northeastern Montana

    NASA Astrophysics Data System (ADS)

    Archibald, J. David; Butler, Robert F.; Lindsay, Everett H.; Clemens, William A.; Dingus, Lowell

    1982-03-01

    Fossils from the Hell Creek and Tullock Formations in northeastern Montana provide detailed documentation of terrestrial faunal and floral evolution during latest Cretaceous (Lancian) and early Paleocene (Puercan) time. Here the replacement of Lancian faunas by those of Puercan age, most obviously signaled by the extinction of dinosaurs, and the changes in pollen floras sometimes used to mark the Cretaceous-Tertiary boundary occurred during a period of reversed magnetic polarity. Paleontological correlations suggest that dinosaur extinction and the change in pollen floras took place in the Red Deer Valley area, Alberta, during the same period of reversed polarity. Furthermore, also on the basis of paleontological correlations, the extinction of dinosaurs in the San Juan Basin, New Mexico, appears to have occurred either during the same period of reversed polarity or, possibly, during the preceding period of normal polarity.

  1. Upper Cretaceous (Maastrichtian) Charophyte Gyrogonites from the Lameta Formation of Jabalpur, Central India: Palaeobiogeographic and Palaeoecological Implications

    NASA Astrophysics Data System (ADS)

    Khosla, Ashu

    2014-12-01

    A charophyte gyrogonite assemblage consisting of Platychara cf. sahnii, Nemegtichara grambastii and Microchara sp. is reported herein from two localities (Bara Simla Hill and Chui Hill sections) of the Lameta Formation at Jabalpur. he Lameta Formation locally underlying the Deccan traps has been shown to be pedogenically modified alluvial plain deposits containing one of the most extensive dinosaur nesting sites in the world. They are associated with dinosaur bones and freshwater ostracod assemblages that suggest a Late Cretaceous (Maastrichtian) age. This is the first detailed systematic account of charophyte gyrogonites from the Lameta Formation. This charophyte assemblage is compatible with the biostratigraphic attribution provided by the ostracods. From a biogeographic viewpoint, it exhibits considerable similarity to other infratrappean assemblages of the Nand, Dongargaon, and Dhamni-Pavna sections (Maharashtra), and some intertrappean assemblages of Kora in Gujarat, Rangapur in Andhra Pradesh and Gurmatkal in South India. Globally, the genus Microchara is well distributed throughout Eurasia, whereas the genus Platychara occurs richly in the Upper Cretaceous deposits of Europe, Asia, America and Africa. However, at the specific level, Platychara cf. sahnii shows close affinities with charophytes from the Maastrichtian of Iran whilst Nemegtichara grambastii shows distinct affinities with two species of Early Palaeogene deposits of China and Mongolia. The presence of charophyte gyrogonites in the Lameta sediments is attributed to local lacustrine and palustrine conditions within a flood plain environment.

  2. Evidence of parasequences in the upper Dakota Formation and Graneros Shale (Cretaceous), central Kansas

    SciTech Connect

    Gellasch, C.A.; Hattin, D.E. . Dept. of Geological Sciences)

    1994-04-01

    The transitional contact between the nearshore, sandstone-dominated Dakota Formation and the deeper marine Graneros Shale in central Kansas formed during the eastward transgression of the Cretaceous Western Interior Sea. The transition was studied in order to (i) describe parasequences contained within it, (ii) interpret the depositional environments represented by the facies making up the parasequences and (iii) produce a paleogeographic reconstruction within the context of a complex sedimentary system associated with the margin of a transgressing sea. Correlation of eight stratigraphic sections in two principle localities of central Kansas was accomplished through petrographic characteristics of sandstones, fossil content, and clay mineral composition. Bentonite beds were utilized as datums to provide a means of analyzing strata in a time-parallel context. Study of these sections between areas of north-central and south-central Kansas shows differences in facies distribution which have been interpreted as evidence of individual parasequences. Previous workers interpreted the transgression of the Western Interior Sea as a response to a uniform rise of relative sea level. However, instead of continuous sea level rise, minor sea level fluctuations led to episodic progradation of the siliciclastic shoreline and formation of parasequences. This is in agreement with work along the former western shoreline of the Western Interior Sea where parasequences have been documented in age-equivalent strata.

  3. A new squamate lizard from the Upper Cretaceous Adamantina Formation (Bauru Group), São Paulo State, Brazil.

    PubMed

    Nava, William R; Martinelli, Agustín G

    2011-03-01

    The record of non-mosasaur squamates (Reptilia, Squamata) is sparse in the Cretaceus fossil record of Brazil and include six putative reports, three from the Aptian-Albian of the Araripe Basin (Tijubina pontei Bonfim-Júnior and Marques, Olindalacerta brasiliensis Evans and Yabumoto, and a lizard indet.) and three from the Upper Cretaceous of the Bauru Group (Pristiguana brasiliensis Estes and Price, Anilioidae gen. et sp. indet., and Squamata gen. et sp. indet.). In this contribution, a new genus and species of lizard, Brasiliguana prudentis gen. et sp. nov., is described based on an isolated left maxilla with teeth. The material was discovered in an outcrop of the Upper Cretaceous Adamantina Formation (Bauru Group) located in the proximity of Presidente Prudente Municipality, São Paulo State, Brazil. The new taxon is considered a basal non-Priscagamidae+Acrodonta iguanian based on the presence of a weakly inclined anterior margin of the maxillary nasal process and maxillary tooth shape and tooth implantation similar to that of iguanians rather than of other lizard groups (e.g. teiids). This finding significantly increases the squamate lizard diversity of South America, which is still poorly understood and sparsely represented in the fossil record. PMID:21437386

  4. A new squamate lizard from the Upper Cretaceous Adamantina Formation (Bauru Group), São Paulo State, Brazil.

    PubMed

    Nava, William R; Martinelli, Agustín G

    2011-03-01

    The record of non-mosasaur squamates (Reptilia, Squamata) is sparse in the Cretaceus fossil record of Brazil and include six putative reports, three from the Aptian-Albian of the Araripe Basin (Tijubina pontei Bonfim-Júnior and Marques, Olindalacerta brasiliensis Evans and Yabumoto, and a lizard indet.) and three from the Upper Cretaceous of the Bauru Group (Pristiguana brasiliensis Estes and Price, Anilioidae gen. et sp. indet., and Squamata gen. et sp. indet.). In this contribution, a new genus and species of lizard, Brasiliguana prudentis gen. et sp. nov., is described based on an isolated left maxilla with teeth. The material was discovered in an outcrop of the Upper Cretaceous Adamantina Formation (Bauru Group) located in the proximity of Presidente Prudente Municipality, São Paulo State, Brazil. The new taxon is considered a basal non-Priscagamidae+Acrodonta iguanian based on the presence of a weakly inclined anterior margin of the maxillary nasal process and maxillary tooth shape and tooth implantation similar to that of iguanians rather than of other lizard groups (e.g. teiids). This finding significantly increases the squamate lizard diversity of South America, which is still poorly understood and sparsely represented in the fossil record.

  5. The Collins Creek and Pleasant Creek Formations: Two new upper cretaceous subsurface units in the Carolina/Georgia Coastal Plain

    USGS Publications Warehouse

    ,; Prowell, D.C.; Christopher, R.A.

    2004-01-01

    This paper formally defines two new Upper Cretaceous subsurface units in the southern Atlantic Coastal Plain of North Carolina, South Carolina and Georgia: the Collins Creek Formation and the Pleasant Creek Formation. These units are confined to the subsurface of the outer Coastal Plain, and their type sections are established in corehole CHN-820 from Charleston County, S.C. The Collins Creek Formation consists of greenish-gray lignitic sand and dark-greenish-gray sandy clay and is documented in cores from Allendale, Beaufort, Berkeley, Dorchester, Jasper and Marion Counties, South Carolina, and from Screven County, Georgia. Previously, Collins Creek strata had been incorrectly assigned to the Middendorf Formation. These sediments occupy a stratigraphic position between the Turonian/Coniacian Cape Fear Formation (?) below and the proposed upper Coniacian to middle Santonian Pleasant Creek Formation above. The Collins Creek Formation is middle and late Coniacian in age on the basis of calcareous nannofossil and palynomorph analyses. The Pleasant Creek Formation consists of olive-gray sand and dark-greenish-gray silty to sandy clay and is documented in cores from New Hanover County, North Carolina, and Berkeley, Charleston, Dorchester, Horry and Marion Counties, South Carolina. The strata of this unit previously were assigned incorrectly to the Middendorf Formation and (or) the Cape Fear Formation. These sediments occupy a stratigraphic position between the proposed Collins Creek Formation below and the Shepherd Grove Formation above. The Pleasant Creek Formation is late Coniacian and middle Santonian in age, on the basis of its calcareous nannofossil and palynomorph assemblages.

  6. Stratigraphy of Blair formation, an Upper Cretaceous slope and basin deposit, eastern flank of the Rock Springs Uplift, Wyoming

    SciTech Connect

    Shannon, L.T.

    1985-05-01

    The Blair Formation (Upper Cretaceous) is the lowermost unit of the Mesaverde Group in southwestern Wyoming. Outcrop study of the Blair exposures on the east flank of the Rock Springs uplift reveals 1,100 ft (330 m) of sandstone, siltstone, and shale. The formation has a sharp conformable to locally erosional basal contact and contains intraformational channeling, syndepositional slumping, and high-energy sedimentary structures. Facies relationships indicate the Blair represents a slope and basinal deposit laterally equivalent to the shelf and delta complex of the lower Rock Springs Formation to the north. Overall stratification types, textures, and southeast paleotransport directions recorded within the Blair, which are normal to the southwest-trending Rock Springs shoreline, support this interpretation. High sedimentation rates in excess of subsidence rates during the early Campanian, possibly related to early movement on the Absaroka thrust and a eustatic lowering of sea level approximately 81 Ma, caused rapid shoreline progradation and favored the development of a narrow shelf. These conditions enabled sand-sized material to bypass the shelf and be deposited in slope and basin environments. A present-day example of these relationships is the modern Mississippi delta located near the shelfslope break of the Gulf of Mexico. Recognition of a narrow shelf in southwestern Wyoming during the early Campanian requires a modification of Late Cretaceous paleogeography to incorporate the concept of depositional topography. The occurrence of slope and basin sandstones in the Blair suggests that new interpretations may be needed to explain sandstone distribution for other stratigraphic intervals within the Cretaceous of the Western Interior.

  7. Cretaceous age of the upper part of the McCoy Mountains Formation, southeastern California and southwestern Arizona, and its tectonic significance: reconciliation of paleobotanical and paleomagnetic evidence.

    USGS Publications Warehouse

    Stone, P.; Page, V.M.; Hamilton, W.; Howard, K.A.

    1987-01-01

    The upper part of the 7-km-thick McCoy Mountains Formation in southeastern California contains fossil angiosperm wood that closely resembles the genus Paraphyllanthoxylon, which is known only from strata of late Early Cretaceous and younger age. This wood, in conjunction with geologic field relations, supports previous interpretations that the upper part of the McCoy Mountains Formation is of late Early Cretaceous and/or Late Cretaceous age, in contrast to a more recent interpretation that the entire formation is of Jurassic age. Alternatives are therefore needed to the recent hypothesis that deposition, deformation, and metamorphism of the McCoy Mountains Formation were related to movement on the Jurassic Mojave-Sonora megashear. -Authors

  8. Paleoecology of unusually well-preserved west coast Upper Cretaceous fossil deposit: Point Loma Formation, Carlsbad, California

    SciTech Connect

    Loch, J.D.; Bottjer, D.J.

    1986-04-01

    Macroinvertebrate fossils are best preserved in southern California Upper Cretaceous strata in the Point Loma Formation at Carlsbad, California. Large bulk-rock samples were removed from a construction site (now covered) that exposed the upper Point Loma at the Carlsbad Research Center. Collections made from a nearby roadcut of the Point Loma along El Camino Real were also studied. The dominant macroinvertebrate (31% of 978 individuals) is an undescribed aporrhaoid gastropod. Although aporrhaoids are present in most Upper Cretaceous deposits in North America, the abundance of these herbivorous mollusks within the Point Loma is unusual. Suspension feeders, including the bivalves Limopsis (28%), Indogrammatodon (5%), Corbula (5%), and Ostrea (4%), form the major trophic group present within this sample (total 57%). Deposit feeders and a diverse suite of predators form the remainder of the paleocommunity (total 4% and 8%, respectively). The two dominant taxa comprise the trophic nucleus of an aporrhaoid-Limopsis paleocommunity. Two taxonomically similar subpopulations can be distinguished within the studied Point Loma. At the El Camino Real site, sandy mudstones supported a subpopulation that attained full adult size. However, at the Carlsbad Research Center, homogeneous mudstones lacking sand yield diminutive fossils of the aporrhaoid-Limopsis paleocommunity. Ichnological evidence of a thixotropic mud bottom indicates that the size reduction was a result of sinking into the unstable substrate rather than other causes (e.g., low oxygenation or salinity). The thixotropic nature of the mudstone contributed to the exceptionally well-preserved fauna. Molluscan hard parts were rapidly buried. Bivalve ligaments, residual color banding, nacreous aragonite, and larval gastropods are preserved. After burial, the low-permeability mudstone insulated skeletons from carbonate dissolution.

  9. Completely preserved cockroaches of the family Mesoblattinidae from the Upper Jurassic-Lower Cretaceous Yixian Formation (Liaoning Province, NE China)

    NASA Astrophysics Data System (ADS)

    Wei, Dandan; Ren, Dong

    2013-08-01

    Although cockroaches were the dominant insects in various Paleozoic and Mesozoic insect assemblages, their general morphology was extremely conservative. One of the most common of them, the Jurassic-Cretaceous family Mesoblattinidae, is described here for the first time on the basis of completely preserved specimens. Ninety-two specimens of Perlucipecta aurea gen. et sp. n. reveal details of head, mandible, male tergal glands and terminal hook; cercal, leg and antennal sensilla. Its congener, P. vrsanskyi is described from the same sediments of the Yixian Formation (Upper Jurassic-Lower Cretaceous). The forewing venation variability of P. aurea, analysed for the first time in this family is nearly identical (CV = 6.23 %) with variability of two species of family Blattulidae that occur at the same locality (CV = 6.22 %; 5.72 %). The transitional nature of morphological characters represented by asymmetry between left and right wings (simple/branched forewing SC and hind wing M) in P. aurea documents the phylogenetic relation between the families Mesoblattinidae and Ectobiidae

  10. Paleotectonic controls on deposition of Niobrara formation, Eagle sandstone, and equivalent rocks (Upper Cretaceous), Montana and South Dakota

    SciTech Connect

    Shurr, G.W.; Rice, D.D.

    1985-05-01

    The deposition of the Niobrara Formation, Eagle Sandstone, and equivalent Upper Cretaceous rocks was controlled by paleotectonic activity on lineament-bound basement blocks in Montana and South Dakota. Linear features observed on Landsat images provide an interpretation of lineament geometry that is independent of stratigraphic data. Paleotectonism on lineament-bound blocks is documented in three areas that were located in distinctly different depositional environments. In central Montana, coastal and inner-shelf sandstones and nonmarine coastal-plain and wave-dominated delta deposits reflect paleotectonic control by lineaments trending north-south, east-west, northwest, and northeast. In the northern Black Hills, chalks and outer-shelf sandstones reflect control by lineaments trending north-south, northwest, and north-east. In central South Dakota, erosion and deposition of chalk and calcareous shale on a west-sloping carbonate ramp were controlled by lineaments that generally trend northeast and northwest. Paleotectonism on lineament-bound blocks characterized four tectonic zones located in the Late Cretaceous seaway; the western foredeep, the west-median trough, the east-median hinge, and the eastern platform. The regional geometry of all four tectonic zones appears to be related to the geometry of the convergent plate margin on the west. Paleotectonic activity on lineament-bound blocks may have been the result of horizontal forces related to the convergent margin and to vertical forces related to the movement of the North American plate.

  11. Stratigraphic revision and depositional environments of the Upper Cretaceous Toreva Formation in the northern Black Mesa area, Navajo and Apache counties, Arizona

    SciTech Connect

    Franczyk, K.J.

    1988-01-01

    Two units previously included in the upper part of the Toreva Formation in northern Black Mesa have been assigned new stratigraphic names. One unit previously assigned to the Toreva is reassigned to the Wepo Formation. This report describes the sedimentology of the Toreva Formation and these new units and the depositional history of the Black Mesa area during middle Turonian through early Santonian time. Correlations are made among these units on Black Mesa and Cretaceous sequences in southern Utah and western New Mexico.

  12. Sedimentology of paleochannels on foreland coastal plain, Judith River Formation (upper Cretaceous), southeast Alberta

    SciTech Connect

    Koster, E.H.

    1984-04-01

    The upper 90 m (295 ft) of the sub-Bearpaw Judith River Formation, continuously exposed in the badlands along the Red Deer River 185 km (115 mi) east of Calgary, is famous for the unrivaled assemblage of dinosaur fossils. Dinosaur Provincial Park presents are a rare opportunity to view the architecture of a foreland coastal-plain sequence as well as to clarify the origin and distribution of subbituminous coal zones and gas reservoirs associated with this formation across southeast Alberta. The distal reaches of paleodrainage from the developing Cordillera to the Western Interior seaway are being examined by north-south traversed across the badlands. Sharp-based paleochannel units, enclosed by rooted, olive-gray mudstone sequences that are commonly 4-6 m (13-20 ft) thick, vary between 2 end members. The first contains laterally accreted sand-mud couplets with abundant macrofloral debris, and represents cyclical, low-energy growth of point bars, possible with an estuarine influence. The second, mainly comprising cosets of large trough cross-beds with mudstone intraclasts, was formed by episodic aggradation of high-energy systems. An intermediate composite type displays evidence for an energy increase as channel sinuosity decreased. This variation in paleochannel type is attributed to alternating alluviation/rejuvenation associated with an unstable base level. Coal zones and potential reservoirs appear to be associated with the transgressive and regressive phases, respectively, of the Bearpaw coast. Amalgamation of paleochannels - marked by laterally extensive horizons of bone fragments, lithic and intraclastic gravel - is more common seaward over the axial region of the Sweetgrass arch.

  13. Lagoonal deposits in the Upper Cretaceous Rock Springs Formation (Mesaverde Group), southwest Wyoming

    USGS Publications Warehouse

    Kirschbaum, M.A.

    1989-01-01

    Most paleogeographic reconstructions of the Rock Springs Formation show shorelines having lobate to arcuate deltas. These shorelines are oriented NE-SW, with the sea to the southeast. Brackish-water bodies are usually shown in interdistributary areas or associated with abandoned delta lobes, and are open to the sea. In this study, a sedimentary sequence 30-50 m thick is interpreted as interdeltaic deposits. Brackish-water deposits within the sequence are interpreted as interdeltaic lagoons rather than interdistributary bays. Three facies associations (units) are recognized in nine measured sections of the study interval. Unit A consists of interbedded sandstone, mudrock and coal which occur in both fining- and coarsening-upward sequences less than 10 m thick. Fining-upward sequences decrease in thickness and frequency upwards in unit A and are interpreted as distributary channels. Coarsening-upward sequences associated with the channels are interpreted as crevasse splays that filled lakes or interdistributary bays. In the upper part of the unit where only minor channels are present, the coarsening-upward sequences are interpreted as bay deltas. Unit B consists of fossiliferous silty shale and bioturbated sandy siltstone. A low-diversity fauna of bivalves, gastropods, ostracods and foraminifers indicates that brackish-water conditions existed. Unit B intertongues with unit A to the northwest and with unit C to the southeast, and is interpreted as lagoonal deposits. Unit C consists of crossbedded and burrowed sandstone in beds 0.5-9 m thick. Sandstones are laterally continuous in the southeast but become tabular bodies enclosed within unit B to the northwest. Laterally continuous sandstones are interpreted as shoreface deposits on the basis of multidirectional crossbeds, marine trace fossils and continuity. Tabular sandstones are interpreted as flood-tidal deltas on the basis of NW-oriented crossbeds, pinchouts to the northwest and enclosure within unit B. Scoured

  14. Sedimentologic evolution of a submarine canyon in a forearc basin, Upper Cretaceous Rosario Formation, San Carlos, Mexico

    SciTech Connect

    Morris, W.R.; Busby-Spera, C.J.

    1988-06-01

    The walls, floor, and fill of a submarine canyon are well-exposed near San Carlos, Mexico, in forecarc strata of the Upper Cretaceous Rosario Formation. The submarine canyon is about 7 km wide and at least 230 m deep and has eroded a minimum of 150 m into underlying fluvial red beds. It is unclear whether subaerial or submarine processes initiated the canyon cutting; however, marine processes, especially debris flows, modified the morphology of the submarine canyon. The submarine canyon fill and overlying slope deposits form two major fining-upward sequences. The first includes a 120 m thick lower conglomerate-sandstone unit (LCSU) at the base of the canyon fill overlain by a 50-110 m thick middle mudstone-sandstone unit (MMSU). The MMSU consists predominantly of mudstone and thin-bedded sandstone, but includes a channel filled with sandstone beds that form a fining- and thinning-upward sequence. This sequence is overlain by the second major sequence, a 0-60 m thick upper conglomerate-sandstone unit (UCSU), which is confined to three channels within the submarine canyon and passes gradationally upward into slope mudstone. Each of the two major fining-upward sequences records a gradual decrease in supply of coarse-grained sediment to the submarine canyon head. The first fining-upward sequence may correspond to a lowstand and subsequent rise in global sea level or, alternatively, may have resulted from local downdropping of the basin. The second fining-upward sequence does not correspond to global sea level fluctuations but is age-correlative with a drop then rise in relative sea level recognized by other workers 300-400 km to the north in the San Diego-Ensenada area. This sea level drop is inferred to have been a regional-scale tectonic event that affect the forearc basin along its length. 18 figures, 2 tables.

  15. Upper cretaceous ammonites of Duwi Formation in Gabal Abu Had and Wadi Hamama, Eastern Desert, Egypt

    NASA Astrophysics Data System (ADS)

    Hamama, H. H.; Kassab, A. S.

    This paper is an attempt to clarify the paleontologic, chronostratigraphic, paleoecologic and biogeographic relations of the heteromorph and sphenodiscid ammonites. The specimens were collected from sharply defined stratigraphic horizons of the Duwi Formation in two sections exposed at G. Abu Hab and Wadi Hamama to the northeast of Qena. Two ammonite zones are recorded in the Duwi Formation: Libycoceras ismaeli (Zittel) Zone and Bostrychoceras polyplocum Zone. The ammonites of the first zone are restricted to the first lower phosphate bed and are only represented by a frequent association of the species Libycoceras ismaeli. This zone defines the base of the Duwi Formation in the area of study. The second zone in the topmost part of the formation is rich in the index species and the other heteromorph ammonites. It is represented by a bed of very hard limestone of thickness about 20 cm at top of the Duwi Formation. The maximum bulk thickness of the formation is 105 m. The stratigraphic range of the fossils of both zones assigns a Campanian age for the sediments of the Duwi Formation in the area of study. Furthermore, the Campanian-Maastrichtian boundary is fixed above the bed with Bostrychoceras polyplocum. The Libycoceras ismaeli (Zittel) is found in a stratigraphic position lower than that published before. The paleontological study of the ammonites led to the recognition of 11 species belonging to 6 genera ( Libycoceras Hyatt, Nostoceras Hyatt Solenoceras Conrad, Bostrychoceras Hyatt, Baculites Lamarck, Exiteloceras Hyatt), and representing 3 families (Sphenodiscidae, Hyatt; Nostoceratidae, Hyatt and Baculitidae Meek). Two new subspecies are described Solenocera a humei aequicostata and Exiteloceras unciforme Lewy qenaense, besides many species which are recorded for the first time in the Egyptian ammonites, they include the followings: Solenoceras cf. reesidei, S. humei densicostata, Nostoceras (Planstoceras) rehavami, Nostoceras cf. dracone and Baculites scotti

  16. Stratigraphy and structural setting of Upper Cretaceous Frontier Formation, western Centennial Mountains, southwestern Montana and southeastern Idaho

    USGS Publications Warehouse

    Dyman, T.S.; Tysdal, R.G.; Perry, W.J.; Nichols, D.J.; Obradovich, J.D.

    2008-01-01

    Stratigraphic, sedimentologic, and palynologic data were used to correlate the Frontier Formation of the western Centennial Mountains with time-equivalent rocks in the Lima Peaks area and other nearby areas in southwestern Montana. The stratigraphic interval studied is in the middle and upper parts (but not uppermost) of the formation based on a comparison of sandstone petrography, palynologic age data, and our interpretation of the structure using a seismic line along the frontal zone of the Centennial Mountains and the adjacent Centennial Valley. The Frontier Formation is comprised of sandstone, siltstone, mudstone, limestone, and silty shale in fluvial and coastal depositional settings. A distinctive characteristic of these strata in the western Centennial Mountains is the absence of conglomerate and conglomeratic sandstone beds. Absence of conglomerate beds may be due to lateral facies changes associated with fluvial systems, a distal fining of grain size, and the absence of both uppermost and lower Frontier rocks in the study area. Palynostratigraphic data indicate a Coniacian age for the Frontier Formation in the western Centennial Mountains. These data are supported by a geochronologic age from the middle part of the Frontier at Lima Peaks indicating a possible late Coniacian-early Santonian age (86.25 ?? 0.38 Ma) for the middle Frontier there. The Frontier Formation in the western Centennial Mountains is comparable in age and thickness to part of the Frontier at Lima Peaks. These rocks represent one of the thickest known sequences of Frontier strata in the Rocky Mountain region. Deposition was from about 95 to 86 Ma (middle Cenomanian to at least early Santonian), during which time, shoreface sandstone of the Telegraph Creek Formation and marine shale of the Cody Shale were deposited to the east in the area now occupied by the Madison Range in southwestern Montana. Frontier strata in the western Centennial Mountains are structurally isolated from other

  17. Lowstand transgressive upper Cretaceous (Coniacian) gravelly deltaic complexes of the Cardium formation, West Central Alberta, Canada

    SciTech Connect

    Thomas, D.V.

    1996-12-31

    A detailed facies and sequence stratigraphic analysis is used to demonstrate the reservoir compartmentalization of gravelly deltaic complexes deposited on a ramp margin in the Western Canadian Sedimentary Basin. Gravelly deltas of the Carrot Creek Member of the Cardium Formation in the Cyn Pem Field area of West Central Alberta occur along well defined backslapping shoreline trends that represent high frequency lowstand to transgressive systems tracts that followed the second order sea level fall ({approximately}90 Ma) of the Turonian. The Cyn Pem Cardium D pool is used to illustrate the detailed sedimentologly and stratigraphy of a gravelly deltaic complex. The pool consists of two distinct coarse-grained delta lobes oriented along a northwest-trending shoreline. Up to 21 meters of gravelly stream mouth bar and distributary channel facles were deposited unconformably on distal marine highstand deposits of the Raven River Member (Turonian) of the Cardium Formation. Production data and facies analysis indicates excellent communication along high permeability (>l Darcy) Gilbert-type deltaic foresets oriented parallel to strike and moderate to poor communication in a depositional dip direction. Poorly sorted gravelly distributary channels dissect the deltaic ioresets. A complex history of high frequency lowstand and transgressive erosion resulted in substantial paleotopographic relief that both bounds and compartmentalizes these gravelly deltaic complexes.

  18. Lowstand transgressive upper Cretaceous (Coniacian) gravelly deltaic complexes of the Cardium formation, West Central Alberta, Canada

    SciTech Connect

    Thomas, D.V. )

    1996-01-01

    A detailed facies and sequence stratigraphic analysis is used to demonstrate the reservoir compartmentalization of gravelly deltaic complexes deposited on a ramp margin in the Western Canadian Sedimentary Basin. Gravelly deltas of the Carrot Creek Member of the Cardium Formation in the Cyn Pem Field area of West Central Alberta occur along well defined backslapping shoreline trends that represent high frequency lowstand to transgressive systems tracts that followed the second order sea level fall ([approximately]90 Ma) of the Turonian. The Cyn Pem Cardium D pool is used to illustrate the detailed sedimentologly and stratigraphy of a gravelly deltaic complex. The pool consists of two distinct coarse-grained delta lobes oriented along a northwest-trending shoreline. Up to 21 meters of gravelly stream mouth bar and distributary channel facles were deposited unconformably on distal marine highstand deposits of the Raven River Member (Turonian) of the Cardium Formation. Production data and facies analysis indicates excellent communication along high permeability (>l Darcy) Gilbert-type deltaic foresets oriented parallel to strike and moderate to poor communication in a depositional dip direction. Poorly sorted gravelly distributary channels dissect the deltaic ioresets. A complex history of high frequency lowstand and transgressive erosion resulted in substantial paleotopographic relief that both bounds and compartmentalizes these gravelly deltaic complexes.

  19. Tectonic and climate control of oil shale deposition in the Upper Cretaceous Qingshankou Formation (Songliao Basin, NE China)

    NASA Astrophysics Data System (ADS)

    Jia, Jianliang; Liu, Zhaojun; Bechtel, Achim; Strobl, Susanne A. I.; Sun, Pingchang

    2013-09-01

    Oil shales were deposited in the Songliao Basin (NE China) during the Upper Cretaceous period, representing excellent hydrocarbon source rocks. High organic matter (OM) contents, a predominance of type-I kerogen, and a low maturity of OM in the oil shales are indicated by bulk geochemical parameters and biomarker data. A major contribution of aquatic organisms and minor inputs from terrigenous land plants to OM input are indicated by n-alkane distribution patterns, composition of steroids, and organic macerals. Strongly reducing bottom water conditions during the deposition of the oil shale sequences are indicated by low pristane/phytane ratios, high C14-aryl-isoprenoid contents, homohopane distribution patterns, and high V/Ni ratios. Enhanced salinity stratification with mesosaline and alkaline bottom waters during deposition of the oil shales are indicated by high gammacerane index values, low MTTC ratios, high β-carotene contents, low TOC/S ratios, and high Sr/Ba ratios. The stratified water column with anoxic conditions in the bottom water enhanced preservation of OM. Moderate input of detrital minerals during the deposition of the oil shale sequences is reflected by titanium concentrations. In this study, environmental conditions in the paleo-lake leading to OM accumulation in the sediments are related to sequence stratigraphy governed by climate and tectonics. The first Member of the Qingshankou Formation (K2qn1) in the Songliao Basin, containing the oil shale sequence, encompasses a third-order sequence that can be divided into three system tracts (transgressive system tract—TST, highstand system tract—HST, and regressive system tract—RST). Enrichment of OM changed from low values during TST-I to high-moderate values during TST-II/III and HST-I/II. Low OM enrichment occurs during RST-I and RST-II. Therefore, the highest enrichment of OM in the sediments is related to stages of mid-late TST and early HST.

  20. Quartz types, authigenic and detrital, in the Upper Cretaceous Eagle Ford Formation, South Texas, USA

    NASA Astrophysics Data System (ADS)

    Milliken, Kitty L.; Ergene, Suzan M.; Ozkan, Aysen

    2016-06-01

    Lithologic heterogeneity of the Eagle Ford Formation in South Texas arises from mixing of extrabasinal grains of siliciclastic composition with intrabasinal grain assemblages composed dominantly of marine carbonate with a lesser component of biosiliceous debris. Detrital quartz in particular is derived from both extrabasinal and intrabasinal sources, posing a challenge for the use of bulk compositional data for mudrock classification. Extrabasinal detrital quartz supplied along a major axis of siliciclastic influx, the Woodbine depositional system of East Texas, is reduced to a minor part of the grain assemblage in South Texas. Petrographic evidence and point-count results indicate that around 85 percent of total quartz in these rocks, equal to about 12.6 volume percent, is authigenic. Thus, significant quantities of authigenic silica are not restricted to siliceous mudrocks, but can be found in carbonate-rich mudrocks as well. Formerly opaline skeletons of radiolaria, the dominant source of silica for authigenic quartz precipitation, are only poorly preserved by replacements including calcite, dolomite, pyrite, and quartz. Dissolved silica released by dissolution of radiolarians, and perhaps also by volcanic glass dissolution is re-precipitated in a variety of forms, including matrix-dispersed microquartz cement, fillings within primary intragranular pores, and grain replacement of both calcareous and siliceous allochems. The mass balance of dissolved silica mobilized from radiolarians and other reactive silicates and the precipitation of authigenic quartz is uncertain because the initial volumes of now-dissolved detrital material versus the final volume of authigenic material (quartz and other authigenic silicates) cannot be determined with accuracy.

  1. Hydrocarbon migration and accumulation in the Upper Cretaceous Qingshankou Formation, Changling Sag, southern Songliao Basin: Insights from integrated analyses of fluid inclusion, oil source correlation and basin modelling

    NASA Astrophysics Data System (ADS)

    Dong, Tian; He, Sheng; Wang, Dexi; Hou, Yuguang

    2014-08-01

    The Upper Cretaceous Qingshankou Formation acts as both the source and reservoir sequence in the Changling Sag, situated in the southern end of the Songliao Basin, northeast China. An integrated approach involving determination of hydrocarbon charging history, oil source correlation and hydrocarbon generation dynamic modeling was used to investigate hydrocarbon migration processes and further predict the favorable targets of hydrocarbon accumulations in the Qingshankou Formation. The hydrocarbon generation and charge history was investigated using fluid inclusion analysis, in combination with stratigraphic burial and thermal modeling. The source rocks began to generate hydrocarbons at around 82 Ma and the hydrocarbon charge event occurred from approximately 78 Ma to the end of Cretaceous (65.5 Ma) when a large tectonic uplift took place. Correlation of stable carbon isotopes of oils and extracts of source rocks indicates that oil was generated mainly from the first member of Qingshankou Formation (K2qn1), suggesting that hydrocarbon may have migrated vertically. Three dimensional (3D) petroleum system modeling was used to evaluate the processes of secondary hydrocarbon migration in the Qingshankou Formation since the latest Cretaceous. During the Late Cretaceous, hydrocarbon, mainly originated from the Qianan depression, migrated laterally to adjacent structural highs. Subsequent tectonic inversion, defined as the late Yanshan Orogeny, significantly changed hydrocarbon migration patterns, probably causing redistribution of primary hydrocarbon reservoirs. In the Tertiary, the Heidimiao depression was buried much deeper than the Qianan depression and became the main source kitchen. Hydrocarbon migration was primarily controlled by fluid potential and generally migrated from relatively high potential areas to low potential areas. Structural highs and lithologic transitions are potential traps for current oil and gas exploration. Finally, several preferred hydrocarbon

  2. Seismic model study of Patrick Draw field, Wyoming: a stratigraphic trap in the Upper Cretaceous Almond Formation

    USGS Publications Warehouse

    Anderson, Robert C.; Ryder, Robert T.

    1978-01-01

    The Patrick Draw field, located on the eastern flank of the Rock Springs uplift in the Washakie basin of southwestern Wyoming, was discovered in 1959 without the use of geophysical methods. The field is a classic example of a stratigraphic trap, where Upper Cretaceous porous sandstone units pinch out on a structural nose. Two-dimensional seismic modeling was used to construct the seismic waveform expressions of the Patrick Draw field, and to better understand how to explore for other 'Patrick Draw' fields. Interpretation of the model shows that the detection of the reservoir sand is very difficult, owing to a combination of acoustic contrasts and bed thickness. Because the model included other major stratigraphic units in the subsurface, several stratigraphic traps are suggested as potential exploration targets.

  3. Hydrothermal dolomitization of the Bekhme formation (Upper Cretaceous), Zagros Basin, Kurdistan Region of Iraq: Record of oil migration and degradation

    NASA Astrophysics Data System (ADS)

    Mansurbeg, Howri; Morad, Daniel; Othman, Rushdy; Morad, Sadoon; Ceriani, Andrea; Al-Aasm, Ihsan; Kolo, Kamal; Spirov, Pavel; Proust, Jean Noel; Preat, Alain; Koyi, Hemin

    2016-07-01

    The common presence of oil seepages in dolostones is widespread in Cretaceous carbonate successions of the Kurdistan Region of Iraq. This integrated field, petrographic, chemical, stable C, O and Sr isotopes, and fluid inclusion study aims to link dolomitization to the origin and geochemical evolution of fluids and oil migration in the Upper Cretaceous Bekhme carbonates. Flux of hot basinal (hydrothermal) brines, which is suggested to have occurred during the Zagros Orogeny, resulted in dolomitization and cementation of vugs and fractures by coarse-crystalline saddle dolomite, equant calcite and anhydrite. The saddle dolomite and host dolostones have similar stable isotopic composition and formed prior to oil migration from hot (81-115 °C) basinal NaCl-MgCl2-H2O brines with salinities of 18-22 wt.% NaCl eq. The equant calcite cement, which surrounds and hence postdates saddle dolomite, has precipitated during oil migration from cooler (60-110 °C) NaCl-CaCl2-H2O brines (14-18 wt.% NaCl eq). The yellowish fluorescence color of oil inclusions in the equant calcite indicates that the oil had API gravity of 15-25° composition, which is lighter than present-day oil in the reservoirs (API of 10-17°). This difference in oil composition is attributed to oil degradation by the flux of meteoric water, which is evidenced by the low δ13C values (- 8.5‰ to - 3.9‰ VPDB) as well as by nil salinity and low temperature in fluid inclusions of late columnar calcite cement. This study demonstrates that linking fluid flux history and related diagenesis to the tectonic evolution of the basin provides important clues to the timing of oil migration, degradation and reservoir evolution.

  4. The taxonomy of a new parvicursorine alvarezsauroid specimen IVPP V20341 (Dinosauria: Theropoda) from the Upper Cretaceous Wulansuhai Formation of Bayan Mandahu, Inner Mongolia, China

    PubMed Central

    Xu, Xing; Stiegler, Josef B.

    2015-01-01

    A new parvicursorine alvarezsauroid theropod specimen IVPP V20341 from the Upper Cretaceous Wulansuhai Formation of Bayan Mandahu, Inner Mongolia, China is described. IVPP V20341 appears to be distinguishable amongst alvarezsauroids by possible cervical procoely and relatively larger semi-circular caudal neural canals, but these features are not proposed as autapomorphies because current knowledge of alvarezsauroid necks and tails remains sparse. IVPP V20341 is distinguishable from Linhenykus—the sole parvicursorine at Bayan Mandahu—by the location of the origination points of the anterior caudal transverse processes; in IVPP V20341 this is the anterodorsal corner of the centra, whereas in Linhenykus it is the posterior end of the prezygapophyses. A number of additional tentative differences between IVPP V20341 and Linhenykus are also identified, but cannot be confirmed until further details of anatomical variation along the neck and tail are revealed by future finds. Thus, following the study of IVPP V20341 there are still seven parvicursorine species from the Upper Cretaceous Gobi Basin, but future finds could increase this to eight species. PMID:26082871

  5. A New Specimen of the Controversial Chasmosaurine Torosaurus latus (Dinosauria: Ceratopsidae) from the Upper Cretaceous Hell Creek Formation of Montana.

    PubMed

    McDonald, Andrew T; Campbell, Carl E; Thomas, Brian

    2016-01-01

    Torosaurus latus is an uncommon and contentious taxon of chasmosaurine ceratopsid known from several upper Maastrichtian units in western North America. We describe a partial parietal of To. latus from the Hell Creek Formation of Montana. Although the specimen's ontogenetic maturity means that it cannot inform the ongoing debate over whether To. latus is the old adult form of the contemporary Triceratops, the specimen is one of the best-preserved To. latus parietals and supplements previous descriptions. PMID:26974149

  6. A New Specimen of the Controversial Chasmosaurine Torosaurus latus (Dinosauria: Ceratopsidae) from the Upper Cretaceous Hell Creek Formation of Montana

    PubMed Central

    McDonald, Andrew T.; Campbell, Carl E.; Thomas, Brian

    2016-01-01

    Torosaurus latus is an uncommon and contentious taxon of chasmosaurine ceratopsid known from several upper Maastrichtian units in western North America. We describe a partial parietal of To. latus from the Hell Creek Formation of Montana. Although the specimen’s ontogenetic maturity means that it cannot inform the ongoing debate over whether To. latus is the old adult form of the contemporary Triceratops, the specimen is one of the best-preserved To. latus parietals and supplements previous descriptions. PMID:26974149

  7. A New Specimen of the Controversial Chasmosaurine Torosaurus latus (Dinosauria: Ceratopsidae) from the Upper Cretaceous Hell Creek Formation of Montana.

    PubMed

    McDonald, Andrew T; Campbell, Carl E; Thomas, Brian

    2016-01-01

    Torosaurus latus is an uncommon and contentious taxon of chasmosaurine ceratopsid known from several upper Maastrichtian units in western North America. We describe a partial parietal of To. latus from the Hell Creek Formation of Montana. Although the specimen's ontogenetic maturity means that it cannot inform the ongoing debate over whether To. latus is the old adult form of the contemporary Triceratops, the specimen is one of the best-preserved To. latus parietals and supplements previous descriptions.

  8. Characterization of the structure, clean-sand percentage, dissolved-solids concentrations, and estimated quantity of groundwater in the Upper Cretaceous Nacatoch Sand and Tokio Formation, Arkansas

    USGS Publications Warehouse

    Gillip, Jonathan A.

    2014-01-01

    The West Gulf Coastal Plain, Mississippi embayment, and underlying Cretaceous aquifers are rich in water resources; however, large parts of the aquifers are largely unusable because of large concentrations of dissolved solids. Cretaceous aquifers are known to have large concentrations of salinity in some parts of Arkansas. The Nacatoch Sand and the Tokio Formation of Upper Cretaceous age were chosen for investigation because these aquifers produce groundwater to wells near their outcrops and have large salinity concentrations away from their outcrop areas. Previous investigations have indicated that dissolved-solids concentrations of groundwater within the Nacatoch Sand, 2–20 miles downdip from the outcrop, render the groundwater as unusable for purposes requiring freshwater. Groundwater within the Tokio Formation also exhibits large concentrations of dissolved solids downdip. Water-quality data showing elevated dissolved-solids concentrations are limited for these Cretaceous aquifers because other shallower aquifers are used for water supply. Although not suitable for many uses, large, unused amounts of saline groundwater are present in these aquifers. Historical borehole geophysical logs were used to determine the geologic and hydrogeologic properties of these Cretaceous aquifers, as well as the quality of the groundwater within the aquifers. Based on the interpretation of borehole geophysical logs, in Arkansas, the altitude of the top of the Nacatoch Sand ranges from more than 200 to less than -4,000 feet; the structural high occurs in the outcrop area and the structural low occurs in southeastern Arkansas near the Desha Basin structural feature. The thickness of the Nacatoch Sand ranges from 0 to over 550 feet. The minimum thickness occurs where the formation pinches out in the outcrop area, and the maximum thickness occurs in the southwestern corner of Arkansas. Other areas of large thickness include the area of the Desha Basin structural feature in

  9. Stratigraphic framework and coal correlation of the Upper Cretaceous Fruitland Formation, Bisti-Ah-Shi-Sle-Pah area, San Juan Basin, New Mexico

    USGS Publications Warehouse

    Flores, Romeo M.; Erpenbeck, Michael F.

    1982-01-01

    This report illustrates and describes the detailed stratigraphic framework and coal correlation of the Upper Cretaceous Fruitland Formation exposed in isolated badlands and along washes within a 20-mile outcrop belt in the Bisti-Ah-Shi-Sle-Pah area, southwestern San Juan Basin, Nex Mexico (see index). The stratigraphic framework showing the vertical and lateral distributions of rock types and the lateral continuity of coal beds is illustrated in cross sections. The cross sections were constructed from 112 stratigraphic sections measured at an average distance of 0.4 mi apart. Each section contained key marker beds (sandstone, coal, and tonstein) that were physically traced to adjacent sections. Each measured section was "hung" on multiple marker beds arranged in a geometric best-fit method that accounts for the differential compaction and facies associations of the deposits. 

  10. Compositional variability of glauconites within the Upper Cretaceous Karai Shale Formation, Cauvery Basin, India: Implications for evaluation of stratigraphic condensation

    NASA Astrophysics Data System (ADS)

    Banerjee, Santanu; Bansal, Udita; Pande, Kanchan; Meena, S. S.

    2016-01-01

    A detailed mineral chemical investigation of glauconite within the condensed section deposits of the Cretaceous Karai Shale Formation, Cauvery Basin, India reflects a wide spectrum in chemical composition related to origin and evolution in different substrates, stratigraphic condensation, and post-depositional alteration. Fe- and Mg-rich glauconite, comprising up to 60% of the sedimentary rocks, occurs as replaced forms of fecal pellets, as infillings within pores and chambers of bioclasts including those of foraminifera, ostracoda, bryozoa, and algae, and as altered forms of mica exhibiting vermiforms. Authigenic precipitation of K- and Fe-poor glauconite, followed by addition of Fe and K into the lattice and concomitant release of Al and Si explains the origin of glauconite pellets and infillings; the origin of glauconite vermiforms in partly degraded mica involves only the second stage of Fe and K addition. Glauconite pellets and vermiforms exhibit sharply defined alteration zones along peripheries to form rims, and in proximity to cracks or cleavages with reduced K2O and Fe2O3 (total) and enhanced Al2O3 and SiO2, related to late-stage meteoric water actions. Cores of glauconite pellets and unaltered zones of vermiforms reflect 'evolved' characteristics with > 6% K2O, typical of a condensed section, while other glauconite varieties occurring at the same stratigraphic level exhibit 'slightly evolved' nature, not consonant with stratigraphic condensation. Increasing abundance of glauconite pellets from the bottom to the top of the transgressive systems tract, accompanied by slight increase in K2O within their cores, reflects the effect of stratigraphic condensation on the evolution of glauconite. High Fe2O3 (total) content of glauconite in the Karai Shale Formation may be related to upwelling, although the Fe may be contributed partly by the biotite substrate. Mössbauer spectroscopy of glauconites reveals significant total Fe substitution in both tetrahedral and

  11. Palynology, palynofacies and petroleum potential of the Upper Cretaceous-Eocene Matulla, Brown Limestone and Thebes formations, Belayim oilfields, central Gulf of Suez, Egypt

    NASA Astrophysics Data System (ADS)

    El Diasty, W. Sh.; El Beialy, S. Y.; Abo Ghonaim, A. A.; Mostafa, A. R.; El Atfy, H.

    2014-07-01

    Palynological, palynofacies and organic geochemical results of 46 samples retrieved from the Upper Cretaceous - Eocene Matulla, Brown Limestone and Thebes formations, Belayim oilfields, central Gulf of Suez, Egypt are presented. The two latter formations are not dated palynologically as their lithology is not promising for palynological yield. However the Matulla Formation is dated as Turonian-Santonian age, based on the combined evidence of pollen and dinocysts. Palynofacies analysis carried out under both transmitted and fluorescent microscopy indicated that both the Thebes and Brown Limestone formations are deposited under a distal suboxic-anoxic environment. On the other hand, the Turonian-Santonian Matulla Formation supported the existence of a marginal marine deposition under dysoxic-anoxic basin to proximal suboxic-anoxic shelf environments. Rock-Eval pyrolysis and TOC results indicated that most of the studied formations are thermally immature to marginally mature and have a good petroleum potential. They are organically-rich in both oil- and gas-prone kerogen Type-II and II/III, deposited under marine reducing conditions favorable for hydrocarbon generation and expulsion.

  12. A new turtle from the Upper Cretaceous Bauru Group of Brazil, updated phylogeny and implications for age of the Santo Anastácio Formation

    NASA Astrophysics Data System (ADS)

    Menegazzo, Mirian Costa; Bertini, Reinaldo José; Manzini, Flávio Fernando

    2015-03-01

    A new Podocnemidinura specimen from the Upper Cretaceous Bauru Group (Paraná Basin) of southeastern Brazil was described. The Bauru Group provided an important portrait of the Brazilian Mesozoic terrestrial biota, which boasts a vertebrate fauna formed from fishes, frogs, lacertilians, crocodyliforms, dinosaurs and mammals; records of palynomorphs; and invertebrate fauna consisted of gastropods, bivalves, ostracods and conchostracans. Nevertheless, the age of these continental deposits is not precisely estimated, which prevents global correlations, and its fauna is argued to be endemic. The new specimen described is the first turtle from the Santo Anastácio Formation, and its morphological comparison with other South American forms provided a significant advancement in the understanding of the age of this unit (Late Cretaceous). This study permitted a revision of the turtle taxa of the Bauru Group. As a result, some taxa were considered synonym, including the new Santo Anastácio form. The specimen is still unnamed due to the absence of skull characters that preclude its accurate positioning within the Bauru Group skull-based taxa. In addition, the phylogenetic affinities of this taxon were analyzed into Podocnemidinura clade.

  13. Geologic map of the Peach Orchard Flat quadrangle, Carbon County, Wyoming, and descriptions of new stratigraphic units in the Upper Cretaceous Lance Formation and Paleocene Fort Union Formation, eastern Greater Green River Basin, Wyoming-Colorado

    USGS Publications Warehouse

    Honey, J.D.; Hettinger, R.D.

    2004-01-01

    This report provides a geologic map of the Peach Orchard Flat 7.5-minute quadrangle, located along the eastern flank of the Washakie Basin, Wyo. Geologic formations and individual coal beds were mapped at a scale of 1:24,000; surface stratigraphic sections were measured and described; and well logs were examined to determine coal correlations and thicknesses in the subsurface. In addition, four lithostratigraphic units were named: the Red Rim Member of the Upper Cretaceous Lance Formation, and the China Butte, Blue Gap, and Overland Members of the Paleocene Fort Union Formation.

  14. Evidence for local tectonism related to a mid-Turonian unconformity beneath Upper Cretaceous Turner Sandy Member of Carlile Formation, northeastern Powder River basin, Wyoming

    SciTech Connect

    Reinbold, M.L.; Harwerth, L.A. )

    1989-09-01

    In the northeastern Powder River basin the Upper Cretaceous (upper Turonian) Turner Sandy Member consists of marine sandstone, siltstone, shale, and bentonites. These lithologies comprise several laterally continuous, primarily upward-coarsening sequences. Turner petroleum production (> 11 million bbl of oil) has been largely from the lowermost sandstone. In this part of the basin, the Turner is conformably overlain by the Sage Breaks shale, but the base of the Turner is, in most areas, unconformable with the underlying Greenhorn Formation. This unconformity records a mid-Turonian sea level lowstand accompanied by widespread erosion. Turner sediments were deposited during the subsequent sea level rise and onlap the erosional surface. Detailed correlations of several shaly or bentonitic marker horizons within the Turner and Greenhorn indicate the unconformity typically occurs at the base of an upward-coarsening sequence. In the far northeast the older Turner sequence may be conformable with the underlying Pool Creek shale. However, to the southwest progressively younger basal Turner sequences onlap progressively older Greenhorn strata at the unconformity. Cross sections and isopach maps document several dominantly north-south-oriented Turner and Greenhorn thins, which they interpret to represent areas of structurally controlled paleohighs. As much as 150 ft of pre-Turner erosion occurs over these paleohighs. Thickness patterns suggest that the greatest uplift immediately preceded the mid-Turonian erosional event. Decreased uplift continued throughout upper Turonian (Turner) time but became much less evident in post-Turner time.

  15. The Lindi Formation (upper Albian-Coniacian) and Tanzania Drilling Project Sites 36-40 (Lower Cretaceous to Paleogene): Lithostratigraphy, biostratigraphy and chemostratigraphy

    NASA Astrophysics Data System (ADS)

    Jiménez Berrocoso, Álvaro; Huber, Brian T.; MacLeod, Kenneth G.; Petrizzo, Maria Rose; Lees, Jacqueline A.; Wendler, Ines; Coxall, Helen; Mweneinda, Amina K.; Falzoni, Francesca; Birch, Heather; Haynes, Shannon J.; Bown, Paul R.; Robinson, Stuart A.; Singano, Joyce M.

    2015-01-01

    The 2009 Tanzania Drilling Project (TDP) expedition to southeastern Tanzania cored a total of 572.3 m of sediments at six new mid-Cretaceous to mid-Paleocene boreholes (TDP Sites 36, 37, 38, 39, 40A, 40B). Added to the sites drilled in 2007 and 2008, the new boreholes confirm the common excellent preservation of planktonic and benthic foraminifera and calcareous nannofossils from core samples that will be used for biostratigraphy, evolutionary studies, paleoceanography and climatic reconstructions from the Tanzanian margin, with implications elsewhere. The new sites verify the presence of a relatively expanded Upper Cretaceous succession in the region that has allowed a new stratigraphic unit, named here as the Lindi Formation (Fm), to be formally defined. The Lindi Fm (upper Albian to Coniacian), extending ∼120 km between Kilwa and Lindi, comprises a 335-m-thick, outer-shelf to upper-slope unit, consisting of dark gray claystone and siltstone interbeds, common finely-laminated intervals, minor cm-thick sandstones and up to 2.6% organic carbon in the Turonian. A subsurface, composite stratotype section is proposed for the Lindi Fm, with a gradational top boundary with the overlying Nangurukuru Fm (Santonian to Maastrichtian) and a sharp bottom contact with underlying upper Albian sandstones. The section cored at TDP Sites 36 and 38 belongs to the Lindi Fm and are of lower to middle Turonian age (planktonic foraminifera Whiteinella archaeocretacea to Helvetoglobotruncana helvetica Zones and nannofossils subzones UC6b ± UC7). The lower portion of TDP Site 39 (uppermost part of the Lindi Fm) is assigned to the lower to upper Coniacian (planktonic foraminifera Dicarinella concavata Zone and nannofossils zone UC 10), while the remaining part of this site is attributed to the Coniacian-Santonian transition and younger Santonian (planktonic foraminifera D. asymetrica Zone and upper part of nannofossils zone UC10). TDP Site 37 recovered relatively expanded (150 m thick

  16. Evidence for a Widespread Disruption Layer Associated With the Cretaceous-Tertiary Boundary in the Upper Fox Hills Formation Throughout the Badland National Park Region of South Dakota

    NASA Astrophysics Data System (ADS)

    Stoffer, P. W.

    2002-12-01

    A widespread zone of disrupted bedding (0.5 to 3.0 m thick) is preserved in the upper Fox Hills Formation throughout the Badlands National Park region. This unit, the Disturbed Zone (DZ), is recognizable in park outcrops extending for twelve miles (east to west) along the crest of the Sage Creek Arch. It also extends at least 20 miles north of the park along the Cheyenne River valley. The DZ features an abundance of soft-sediment liquefaction characteristics including rolled-up sandy beds (now mostly concretions) with an east-to-west axis orientation. The current mapped extent of the DZ covers about 3,000 square kilometers in central South Dakota, but may be much greater. In the park, the DZ unit rest on top of richly fossiliferous marine marls bearing marine mollusks (mostly ammonites and belemnites) of Late Maestrichtian age. After many seasons of searching, the sandstone and shale units overlying the DZ have not yielded any Cretaceous fossils. However, the overlying beds do preserve an abundance of small traces fossils, arthropod and fish remains, and plant material. In the park, this uppermost unit above the DZ ranges up to 16 meters thick, and the upper part preserves a series of paleosols known locally as the Yellow Mounds. The Fox Hills Formation in the park preserves the same biozonation sequence as the Type Fox Hills in the Missouri Valley region. In both regions the thickness of the formation varies, but the measurable maximum thickness is about the same (50 meters). In the Badlands National Park area, structural patterns preserved in the underlying Pierre Shale seem to have influenced sedimentation characteristics (including sand content and fossil distribution) in the overlying Fox Hills Formation. In addition, the thickness of the Fox Hills Formation is controlled by the distribution and pattern of ancient stream valleys preserved beneath the overlying Tertiary White River Group.

  17. Spatial variation in quartz cement type and concentration: An example from the Heidelberg formation (Teufelsmauer outcrops), Upper Cretaceous Subhercynian Basin, Germany

    NASA Astrophysics Data System (ADS)

    Fischer, Cornelius; Waldmann, Svenja; von Eynatten, Hilmar

    2013-06-01

    Spatial heterogeneity of cement abundance in sandstones is an important factor for reservoir compartmentalization. Here we present results on the variety of diagenetic products and spatial distribution of intense and focused silica cementation within otherwise friable sandstone without silica cements. The Cretaceous quartz arenite of the Teufelsmauer outcrops near Quedlinburg (Upper Cretaceous Heidelberg formation, Subhercynian Basin, Germany) is cemented by various types of diagenetic silica. The highly cemented sandstone sections contain both syntaxial quartz cement (concentrations: 11-31 vol.%) and microcrystalline pore-filling quartz cement (10-34 vol.%). Microcrystalline cement generations form the latest SiO2 precipitations and overgrow moderate to intense syntaxial rims. At outcrop and sedimentary basin scales, the occurrence of highly cemented sandstone is limited to an area of several hundreds of meters in lateral extension, but does not exceed a layer thickness of about 5 m. The highly cemented sandstone shows internal heterogeneity in cementation with preferred orientation of their length axis, suggesting mainly stationary fluid flow pathways during cementation of several silica generations. Most likely, the source of all diagenetic silica is owing to enhanced dissolution at cataclastic deformation bands, which are found within the same sandstone strata. As a mechanism for locally focused precipitation, we suggest a combination of (1) local enhancement of silica dissolution due to deformation and cataclasis and (2) enhanced fluid flow and expulsion during deformation related to the synchronous thrusting of the Harz block onto the Cretaceous Subhercynian Basin. We interpret that the expelled silica-enriched formation water experienced fluid mixing with ascending water from an overpressured, deeper regime, implying that the observed silica generations trace this unique zone of fluid expulsion, ascension, and mixing. Our investigations show that silica

  18. A Re-Evaluation of the Chasmosaurine Ceratopsid Genus Chasmosaurus (Dinosauria: Ornithischia) from the Upper Cretaceous (Campanian) Dinosaur Park Formation of Western Canada

    PubMed Central

    Campbell, James A.; Ryan, Michael J.; Holmes, Robert B.; Schröder-Adams, Claudia J.

    2016-01-01

    Background The chasmosaurine ceratopsid Chasmosaurus is known from the Upper Cretaceous (Campanian) Dinosaur Park Formation of southern Alberta and Saskatchewan. Two valid species, Chasmosaurus belli and C. russelli, have been diagnosed by differences in cranial ornamentation. Their validity has been supported, in part, by the reported stratigraphic segregation of chasmosaurines in the Dinosaur Park Formation, with C. belli and C. russelli occurring in discrete, successive zones within the formation. Results/Conclusions An analysis of every potentially taxonomically informative chasmosaurine specimen from the Dinosaur Park Formation indicates that C. belli and C. russelli have indistinguishable ontogenetic histories and overlapping stratigraphic intervals. Neither taxon exhibits autapomorphies, nor a unique set of apomorphies, but they can be separated and diagnosed by a single phylogenetically informative character—the embayment angle formed by the posterior parietal bars relative to the parietal midline. Although relatively deeply embayed specimens (C. russelli) generally have relatively longer postorbital horncores than specimens with more shallow embayments (C. belli), neither this horncore character nor epiparietal morphology can be used to consistently distinguish every specimen of C. belli from C. russelli. Status of Kosmoceratops in the Dinosaur Park Formation Kosmoceratops is purportedly represented in the Dinosaur Park Formation by a specimen previously referred to Chasmosaurus. The reassignment of this specimen to Kosmoceratops is unsupported here, as it is based on features that are either influenced by taphonomy or within the realm of individual variation for Chasmosaurus. Therefore, we conclude that Kosmoceratops is not present in the Dinosaur Park Formation, but is instead restricted to southern Laramidia, as originally posited. PMID:26726769

  19. The coal-forming plants of the upper part of the Lower Cretaceous Starosuchan Formation (Partizansk Basin, South Primorye region)

    NASA Astrophysics Data System (ADS)

    Bugdaeva, E. V.; Markevich, V. S.; Volynets, E. B.

    2014-05-01

    The plant remains and palynological assemblages are studied in detail in the section of the coal-bearing upper part of the Aptian Starosuchan Formation near the village of Molchanovka (Partizansk Basin, South Primorye region). On the basis of the light and electron microscopic study of the disperse cuticles, it was established that the coals are mostly composed of remains of taxodialean Elatides asiatica (Yok.) Krassil., subordinate Miroviaceae, rare ginkgoalean Pseudotorellia sp., and bennettite Nilssoniopteris rithidorachis (Krysht.) Krassil. The spores Gleicheniidites and pollen Taxodiaceaepollenites are dominant in the palynospectrum of the coal interlayer. It was found that dominant taxodialeans and gleicheniaceous ferns with less abundant Miroviaceae, ginkgoaleans, and rare bennettites occurred in the Aptian swamp communities of the Partizansk basin. Shoots and leaves of Elatides asiatica, fronds of Birisia onychioides (Vassil. et K.-M.) Samyl., are dominant in the burials of plants from the clastic rocks. The fragments of leaves of Nilssoniopteris, scale-leaved conifers, and Ginkgo ex gr. adiantoides are rare. The disperse cuticle of these layers mostly includes Pseudotorellia sp.; however, its remains in burials were not found. The spores Laevigatosporites are dominant in the palynospectra from the clastic interlayers. Ginkgocycadophytus and taxa close to Pinaceae are plentiful among the pollen of gymnosperms.

  20. Taphonomy of a Baurusuchus (Crocodyliformes, Baurusuchidae) from the Adamantina Formation (Upper Cretaceous, Bauru Basin), Brazil: Implications for preservational modes, time resolution and paleoecology

    NASA Astrophysics Data System (ADS)

    Araújo Júnior, Hermínio Ismael de; Silva Marinho, Thiago da

    2013-11-01

    Upper Cretaceous vertebrate accumulations from the Adamantina Formation are known due to their high taxonomic diversity. On the other hand, taphonomic analyses still are rare, limiting the understanding of processes related to the biostratinomic and fossildiagenetic histories of this lithostratigraphic unit. In 2005, fossils were collected from an outcrop located at Jales municipality, state of São Paulo, southeastern Brazil. From this outcrop, a well-preserved Baurusuchus was recovered, which displays a peculiar set of taphonomic signatures. This paper identifies and interprets taphonomic features of a specimen of Baurusuchus (Crocodyliformes, Baurusuchidae; UFRJ DG 418-R) from the Adamantina Formation (Upper Cretaceous of the Bauru Basin), in Jales municipality, state of São Paulo. Brief taphonomic comparisons with other specimens previously studied (crocodiles and dinosaurs) and a lithofaciological analysis of the outcrop were undertaken in order to enhance the knowledge of the stratigraphy and paleoenvironment and improve the time resolution for the Adamantina Formation in the region of Jales. Furthermore, paleoecological data were interpreted based on the taphonomic analysis. The fossil is composed of an articulated segment of vertebral column, ribs, part of the pelvic girdle and gastralia. There is no hydraulic equivalence between both the specimen of Baurusuchus and the size of quartz grain predominant in the fossiliferous layer, suggesting death in situ or short transport as a “water carcass”. Teeth marks identified on the pubes were assigned to a small/juvenile baurusuchid crocodyliform or a theropod dinosaur. The repositioning of some elements (ribs and dorsal osteoderms) is suggestive of mummification. Desiccation marks were observed and attributed to the stage 1 of weathering. These features suggest subaerial exposure of the carcass prior to burial, however, probably after the mummification. On the other hand, the subaerial exposure was short

  1. Nonassociated gas resources in low-permeability sandstone reservoirs, lower tertiary Wasatch Formation, and upper Cretaceous Mesaverde Group, Uinta Basin, Utah

    SciTech Connect

    Fouch, T.D.; Schmoker, J.W.; Boone, L.E.; Wandrey, C.J.; Crovelli, R.A.; Butler, W.C.

    1994-08-01

    The US Geological Survey recognizes six major plays for nonassociated gas in Tertiary and Upper Cretaceous low-permeability strata of the Uinta Basin, Utah. For purposes of this study, plays without gas/water contacts are separated from those with such contacts. Continuous-saturation accumulations are essentially single fields, so large in areal extent and so heterogeneous that their development cannot be properly modeled as field growth. Fields developed in gas-saturated plays are not restricted to structural or stratigraphic traps and they are developed in any structural position where permeability conduits occur such as that provided by natural open fractures. Other fields in the basin have gas/water contacts and the rocks are water-bearing away from structural culmination`s. The plays can be assigned to two groups. Group 1 plays are those in which gas/water contacts are rare to absent and the strata are gas saturated. Group 2 plays contain reservoirs in which both gas-saturated strata and rocks with gas/water contacts seem to coexist. Most units in the basin that have received a Federal Energy Regulatory Commission (FERC) designation as tight are in the main producing areas and are within Group 1 plays. Some rocks in Group 2 plays may not meet FERC requirements as tight reservoirs. However, we suggest that in the Uinta Basin that the extent of low-permeability rocks, and therefore resources, extends well beyond the limits of current FERC designated boundaries for tight reservoirs. Potential additions to gas reserves from gas-saturated tight reservoirs in the Tertiary Wasatch Formation and Cretaceous Mesaverde Group in the Uinta Basin, Utah is 10 TCF. If the potential additions to reserves in strata in which both gas-saturated and free water-bearing rocks exist are added to those of Group 1 plays, the volume is 13 TCF.

  2. Outcrops, Fossils, Geophysical Logs, and Tectonic Interpretations of the Upper Cretaceous Frontier Formation and Contiguous Strata in the Bighorn Basin, Wyoming and Montana

    USGS Publications Warehouse

    Merewether, E.A.; Cobban, W.A.; Tillman, R.W.

    2010-01-01

    In the Bighorn Basin of north-central Wyoming and south-central Montana, the Frontier Formation of early Late Cretaceous age consists of siliciclastic, bentonitic, and carbonaceous beds that were deposited in marine, brackish-water, and continental environments. Most lithologic units are laterally discontinuous. The Frontier Formation conformably overlies the Mowry Shale and is conformably overlain by the Cody Shale. Molluscan fossils collected from outcrops of these formations and listed in this report are mainly of marine origin and of Cenomanian, Turonian, and Coniacian ages. The lower and thicker part of the Frontier in the Bighorn Basin is of Cenomanian age and laterally equivalent to the Belle Fourche Member of the Frontier in central Wyoming. Near the west edge of the basin, these basal strata are disconformably overlain by middle Turonian beds that are the age equivalent of the Emigrant Gap Member of the Frontier in central Wyoming. The middle Turonian beds are disconformably overlain by lower Coniacian strata. Cenomanian strata along the south and east margins of the basin are disconformably overlain by upper Turonian beds in the upper part of the Frontier, as well as in the lower part of the Cody; these are, in turn, conformably overlain by lower Coniacian strata. Thicknesses and ages of Cenomanian strata in the Bighorn Basin and adjoining regions are evidence of regional differential erosion and the presence of an uplift during the early Turonian centered in northwestern Wyoming, west of the basin, probably associated with a eustatic event. The truncated Cenomanian strata were buried by lower middle Turonian beds during a marine transgression and possibly during regional subsidence and a eustatic rise. An uplift in the late middle Turonian, centered in north-central Wyoming and possibly associated with a eustatic fall, caused the erosion of lower middle Turonian beds in southern and eastern areas of the basin as well as in an adjoining region of north

  3. Regional analysis of rhythmic bedding in the Fort Hays limestone member, Niobrara Formation (Upper Cretaceous), US western interior

    SciTech Connect

    Laferriere, A.P.

    1987-01-01

    Results of a regional stratigraphic investigation of the rhythmically bedded Fort Hays limestone member of Kansas, Colorado, and New Mexico indicate at least two levels of cyclicity. Regional development of these cycles strongly supports the hypothesis that they are climatic in origin. Departures from simple cyclical patterns resulted from sedimentary effects of Late Cretaceous orogenic activity, erosional events associated with eustatic sea level changes, diagenetic modification, and possibly from interference between orbital parameters having different periodicities. The vulnerability of Milankovitch-type cyclicity to overprinting by tectono-sedimentologic effects makes units such as the Fort Hays useful as indicators of subtle tectonic activity. Regional thickness changes in groups of shale-limestone couplets were identified, correlated, and mapped in the subsurface using geophysical well log information in order to locate subtle structural elements that influenced Fort Hays sedimentation. In the Denver-Julesburg Basin of Colorado and western Kansas, thinning of the section between Fort Hays marker horizons occurs dominantly along northeastwardly trending belts that resulted apparently from Late Cretaceous reactivation of the Transcontinental Arch. Isotopic and petrographic analyses were conducted on pelagic (carbonate matrix) and benthic (inoceramid bivalve) constituents of selected shale/limestone couplets. These data suggest that there was little difference in temperature or salinity between times of terrigenous detrital input and times of nearly pure carbonate deposition. Isotopic information from matrix samples suggests a westward decrease in salinity of surface water in the Western Interior Sea. Isotopic data from largely unaltered inoceramid bivalves indicate bottom-water conditions of near-normal marine salinity.

  4. Peat accumulation in coastal-plain mires: a model for coals of the Fruitland Formation (Upper Cretaceous) of southern Colorado, USA

    USGS Publications Warehouse

    Robinson, Roberts L.N.; McCabe, P.J.

    1992-01-01

    In the northwestern part of the San Juan basin, Colorado, thick high-volatile B bituminous coal deposits in the Upper Cretaceous Fruitland Formation are associated with nearshore marine sandstones of the Pictured Cliffs Sandstone. Detailed work along the outcrop and examination of drill cores, revealed two coal-bearing zones in the lower 60 m of the Fruitland Formation. Each zone is up to 13 m thick and consists of interbedded bright and dull coal (average ash values of 17 and 34% on a moisture-free basis, respectively), thin fine-grained clastic partings and abundant altered volcanic ash partings. Isopachs of the interval between the top of the Pictured Cliffs Sandstone and a marker bed (Huerfanito Bentonite Bed) in the underlying Lewis Shale show linear zones where the interval abruptly thickens. These zones, which trend northwest to southeast, represent areas where the shoreline paused during an overall migration to the northeast. Isopach maps of coal in the lower part of the Fruitland Formation and subsurface correlation of shoreface sandstones with coal zones show that the thickest accumulation of coal is 20-25 km landward of these coeval shorelines. The Fruitland coals may be compared to the high-ash peats of the Dismal Swamp in the southeastern U.S.A., which form in pocosin mires about 20 km inland from the Atlantic coast. Clastic deposirion, resulting from coastal processes, precludes the formation of peat in low-lying mires adjacent to the shoreline. The high ash yield, numerous partings and the relationship with the coeval shoreline suggest that the coals in the lower part of the Fruitland Formation accumulated in mires that were transitional from low-lying to raised. ?? 1992.

  5. The mechanism of skeletal aragonite neomorphism: evidence from neomorphosed mollusks from the upper Purbeck Formation (Late Jurassic-Early Cretaceous), southern England

    NASA Astrophysics Data System (ADS)

    Maliva, Robert G.; Dickson, J. A. D.

    1992-03-01

    The trace element geochemistry and microtextures of neomorphosed mollusks from the upper Purbeck Formation (Late Jurassic-Early Cretaceous) of southern England suggest that calcite replacement of aragonite occurs by a force of crystallization-driven mechanism similar to that of non-polymorphic skeletal carbonate replacement reactions, such as silicification. The Purbeck neomorphic calcites are substantially enriched in Mg, Mn, and Fe, and depleted in Sr compared to skeletal aragonite indicating that the neomorphic reaction zones were not chemically isolated from the bulk pore waters to a significant degree. Neomorphic calcite microtextures are fundamentally similar to the replacement microtextures of silicified and celestite-replaced fossils, in terms of the degree and style of preservation of traces of skeletal microtextures in authigenic crystals and the relationships of authigenic crystal morphology and crystallographic orientation to shell microtexture. The neomorphic replacement of aragonite by calcite differs from most non-polymorphic replacement reactions in that the calcite cannibalizes aragonite. Decreases in the intraskeletal pore water calcium carbonate ion activity product caused by calcite precipitation results in aragonite dissolution adjacent to aragonite-calcite contacts (i.e., chalkification) in some fossils. Chalkification does not occur in non-polymorphic replacements of skeletal carbonate.

  6. The application of petrophysics to resolve fluid flow units and reservoir quality in the Upper Cretaceous Formations: Abu Sennan oil field, Egypt

    NASA Astrophysics Data System (ADS)

    Lala, Amir Maher Sayed; El-sayed, Nahla Abd El-Aziz

    2015-02-01

    Petrophysical flow unit concept can be used to resolve some of the key challenges faced in the characterization of hydrocarbon reservoirs. The present study deals with petrophysical evaluation of some physical properties of the Upper Cretaceous rock samples obtained from the Abu-Roash and the Bahariya Formations at southwest of Sennan oil field in the Western Desert of Egypt. The aim of this study was achieved through carrying out some petrophysical measurements of porosity, bulk density, permeability, mean hydraulic radius (Rh), irreducible water saturation, and radius of pore throat at mercury saturation of 35% in order to determine reservoir characteristics. In this study, the relationships obtained between the measured petrophysical properties such as porosity, permeability and pore throat flow unit types were established for 53 sandstone core samples obtained from two different stratigraphic units. Flow zone indicator (FZI) has been calculated to quantify the flow character of the Abu-Roash and Bahariya reservoir rocks based on empirically derived equations of robust correlation coefficients. The correlations among porosity, permeability, bulk density, mean hydraulic radius and pore throat flow properties reflect the most important reservoir behavior characteristics. The calculated multiple regression models indicate close correlation among petrophysical properties and Rh and R35%. The obtained models are able to predict Rh and R35% by using porosity and permeability, to map reservoir performance and predict the location of stratigraphic traps.

  7. Giant Upper Cretaceous oysters from the Gulf coast and Caribbean

    USGS Publications Warehouse

    Sohl, Norman F.; Kauffman, Erle G.

    1964-01-01

    Two unusually massive ostreid species, representing the largest and youngest Mesozoic members of their respective lineages, occur in Upper Cretaceous sediment of the gulf coast and Caribbean areas. Their characteristics and significance, as well as the morphologic terminology of ostreids in general, are discussed. Crassostrea cusseta Sohl and Kauffman n. sp. is the largest known ostreid from Mesozoic rocks of North America; it occurs sporadically in the Cusseta Sand and rarely in the Blufftown Formation of the Chattahoochee River region in Georgia and Alabama. It is especially notable in that it lacks a detectable posterior adductor muscle scar on large adult shells. C. cusseta is the terminal Cretaceous member of the C. soleniscus lineage in gulf coast sediments; the lineage continues, however, with little basic modification, throughout the Cenozoic, being represented in the Eocene by C. gigantissima (Finch) and probably, in modern times, by C. virginica (Gmelin). The C. soleniscus lineage is the first typically modern crassostreid group recognized in the Mesozoic. Arctostrea aguilerae (Böse) occurs in Late Campanian and Early Maestrichtian sediments of Alabama, Mississippi, Texas(?), Mexico, and Cuba. The mature shell of this species is larger and more massive than that of any other known arctostreid. Arctostrea is well represented throughout the Upper Jurassic and Cretaceous of Europe, but in North America, despite the great numbers and diversity of Cretaceous oysters, only A. aguilerae and the Albian form A. carinata are known. The presence of A. aquilerae in both the Caribbean and gulf coast faunas is exceptional, as the Late Cretaceous faunas of these provinces are generally distinct and originated in different faunal realms.

  8. Upper Cretaceous to Lower Miocene of the Subsilesian Unit (Western Carpathians, Czech Republic): stratotypes of formations revised

    NASA Astrophysics Data System (ADS)

    Bubík, Miroslav; Franců, Juraj; Gilíková, Helena; Otava, Jiří; Švábenická, Lilian

    2016-06-01

    Type sections/areas for all four formations distinguished in the sedimentary succession of the Subsilesian Unit on Czech territory were revisited and described. New data on lithology, sedimentology, fossil record, biostratigraphy, heavy-minerals and geochemical proxies are based on observations and analysis of these sections. The historical type section of the Frýdek Formation was destroyed during railway construction in 19th century. Outcrops of Campanian to Maastrichtian marls and sandstones on the southwestern slope of "Castle hill" at Frýdek, are proposed as a new type section. The Ostravice riverbed in Frýdlant nad Ostravicí was originally designated as the type area, not mentioning the particular section. This area, even when supplemented with Sibudov Creek, does not show all typical facies of the formation. The outcrops range from lowermost Eocene to Eocene-Oligocene transition. In the original description of the Menilite Formation Glocker mentioned several localities in the area covering the Ždanice, Subsilesian and Silesian units, not mentioning the principal one. The single sections, each not exceeding a thickness of 2 m, are not sufficient to be a type section. Instead of that, we propose the area between Paršovice and Bystřice pod Hostýnem, covering the historical localities, as the type area. The type locality of the Ženklava Formation is an outcrop in an unnamed creek in Ženklava according to the original definition. It seems to be reasonable to extend the type section to the whole 500 m long section of the creek with the outcrops that better illustrate the lithological variability of the formation. New biostratigraphic data allow assignment to late Egerian (Eggenburgian?).

  9. New petrofacies in upper Cretaceous section of southern California

    SciTech Connect

    Colburn, I.P.; Oliver, D.

    1986-04-01

    A distinctive sandstone-conglomerate petrofacies is recognized throughout the Late Cretaceous (Maestrichtian-late Campanian) Chatsworth Formation in the Simi Hills. It is named the Woolsey Canyon petrofacies after the district where it was first recognized. The petrofacies is also recognized in the Late Cretaceous (late Campanian and possibly early Maestrichtian) Tuna Canyon Formation of the central Santa Monica Mountains. The conglomerates in the petrofacies are composed predominantly of angular pebble-size clasts of argillite, quartz-rich rocks (orthoquartzarenite, metaorthoquartzarenite, mice quartz schist) and leucocratic plutoniate (granite-granodiorite). The conglomerate texture and composition are mirrored in the sandstone. The uniformly angular character of the conglomerate clasts and the survival of argillite clasts indicate that the detritus underwent no more than 5 mi of subaerial transport before it entered the deep marine realm. Foraminifers collected from mudstones interbedded with the conglomerates indicate upper bathyal water depth at the site of deposition. A source terrane of low to moderate relief is indicated by the absence of cobbles and boulders. Bed forms, sedimentary structures, and textural features indicate the detritus moved north from its source terrane to be deposited by turbidity currents, debris flows, and grain flows on the Chatsworth Submarine Fan. The detritus of the Woolsey Canyon petrofacies was derived from basement rocks, now largely buried beneath the Los Angeles basin, that were being eroded during the formation of the Cretaceous Los Angeles erosion surface. The detritus came from the Los Angeles arch of that surface.

  10. Formation, diagenesis and FOC-RFC cementation of fossiliferous concretions of the Fox Hills Fm. , (Upper Cretaceous) of North Dakota

    SciTech Connect

    Carpenter, S.J.; Erickson, J.M.; Owen, M.R.

    1985-01-01

    Carbonate-cemented, fossil-rich concretions are a prominent feature in the clastic, marine rocks of the Fox Hills Fm., of North Dakota and South Dakota. Preliminary petrographic, paleontologic, chemical and isotopic data from three sandstone concretions suggest initial nucleation at very shallow burial depths (< 1m). Decomposition of organic-rich fecal material produced localized anoxic and alkaline conditions which induced phosphatization, sulfate reduction (pyrite formation) and possibly adipocire (Ca(RCOO)/sub 2/) formation. These processes were responsible for the formation of an unlithified proto-concretion. The elevated pH at the concretion site allowed calcite precipitation while calcareous shell material in the surrounding sediment experience dissolution. Transformation of adipocire (.) produced a ferroan isopachous carbonate cement. Following this, Fascicular-optic and Radiaxial-fibrous calcite, volumetrically the most significant cement was precipitated. RFC represents the morphological transition from acicular FOC to the late stage, equant, Blocky Calcite (BC). Scanning Electron Microscopy of FOC-RFC indicates the habit of radiating crystals and constituent subcrystals and suggests causes for the unusual optical properties of FOC and RFC. Atomic Absorption data demonstrate decreases in Mg, Fe, Sr and Mn between FOC and BC. Cathodoluminescence (CL) reveals gradational boundaries between morphologically distinct cements and a bright zone corresponding to RFC. Most well preserved aragonitic shells indicate few signs of replacement by calcite. However, some pelecypod shells show an unusual form of replacement whereby shell volume and structure are preserved, although completely replaced by FOC. CL also reveals the amount of replacement as indicated by a blending of carbonate luminescent colors (calcite = red; aragonite = blue).

  11. Early and late lithification of aragonitic bivalve beds in the Purbeck Formation (upper jurassic-lower cretaceous) of Southern England

    NASA Astrophysics Data System (ADS)

    El-Shahat, Adam; West, Ian

    1983-05-01

    Beds of euryhaline bivalves alternating with shales constitute much of the middle Purbeck Formation. They originated on "tidal" flats at the western margin of an extensive brackish lagoon. When these shell beds are thin and enclosed in shale they are often still preserved as aragonite and are associated with "beef", fibrous calcite formed during compaction. In most cases, however, the shell debris has been converted by diagenesis into calcitic biosparrudite limestones. A compacted type has been lithified at a late stage, after deep burial. In this, pyrite is abundant and most of the shell aragonite has been replaced neomorphically by ferroan pseudopleochroic calcite. A contrasting uncompacted type of biosparrudite is characterised by bivalve fragments with micrite envelopes. Shells and former pores are occupied by non-ferroan sparry calcite cement, and there is little pyrite. These limestones frequently contain dinosaur footprints and originated in "supratidal" environments where they were cemented early, mainly in meteoric water. Once lithified they were unaffected by compaction. This uncompacted type indicates phases of mild uplift or halts in subsidence. These shell-bed lithologies, and also intermediate types described here, will probably be recognised in other lagoonal formations.

  12. The Kimmeridge Clay Formation (Upper Jurassic-Lower Cretaceous) of the Norwegian continental shelf and Dorset, UK: a chemostratigraphical correlation

    NASA Astrophysics Data System (ADS)

    Turner, Holly; Gale, Andy; Gradstein, Felix

    2016-04-01

    The type section of the Kimmeridge Clay Formation (KCF) at Dorset, (UK) stands at the forefront in multidisciplinary research on climatic cyclicity, orbital forcing, sea level change and the productivity vs. preservation controversy. In economic terms, it is a prime source rock of the North Sea hydrocarbon province containing up to 35% total organic carbon. Lateral equivalents of the KCF occur widely in the North, Norwegian and Barents Sea regions of north-western Europe under other names: the Draupne, Mandal, Spekk, Hekkingen and Agardhfjellet (Svalbard) formations. Carbon isotopes and clay mineralogy have been extensively studied from the KCF type section at Dorset. However, between the North Sea and Western Barents Sea, little is known of these records. Correlation using both clay mineral and δ13Corg profiles across these areas would provide insights for our understanding of Late Jurassic climatic developments in north-western Europe. New chemostratigraphical records through the KCF of five Norwegian exploration wells of Lundin Petroleum and one of Statoil, are compared with the Kimmeridgian of Sub-Boreal Dorset, along with a correlation between Svalbard records with the Tithonian cores sampled in this project. Dinoflagellate biostratigraphy accompanies isotope stratigraphy in the placement of each core in time. Initial results show a strong overall correlation. On a smaller timescale, several events are described from Dorset, including a distinct mid-Eudoxus positive isotope peak reflecting a sea level rise, and the Hudlestoni aridity peak as recorded by low kaolinite/illite ratios. Off the Norwegian Continental Shelf, how are these events recorded, if recorded at all, in a δ13Corg and clay mineralogical profile? Such events are useful tools in correlation, and their identification regionally reduces the likelihood of local influence on oceanographical conditions, such as palaeoproductivity response to nutrient influxes, and instead reflects changes in the

  13. Source area and depositional controls on diagenesis in the deep lower Tuscaloosa Formation (Upper Cretaceous), Gulf Coast

    SciTech Connect

    Weedman, S.D.; Brantley, S.L. . Geosciences Dept.)

    1992-01-01

    Sandstone cores from two widely separated gas fields within the deep lower Tuscaloosa Formation were sampled and examined with optical, cathodoluminescent, and scanning electron microscopy. Diagenetic differences between the two areas (the Moore-Sams/Morganza (MS/M) and Rigolets (R) fields) can be explained by different source areas and depositional environments. The coarsening-upward reservoir sandstones of the MS/M fields were deposited along a prograding delta front, where sand/shale ratios of at least 4:1 indicate extensive sandstone connectivity. Sandstone isolith maps suggest a source area to the north including areas of contemporaneous (Cenomanian) alkaline volcanic activity in Louisiana, Mississippi, and Arkansas. The sandstones have extremely high porosity, interpreted as secondary, despite burial depths. Porosity is preserved where compaction is inhibited by relict cements and overpressures. Additionally, pores are lined with an iron-rich chlorite, which inhibits late quartz cement. Sedimentary structures and sand/shale ratios in lower Tuscaloosa sandstones of the R field suggest more distal, shale-dominated depositional environments. Sandstone isolith maps indicate a source area to the northeast, to sandstones of the MS/M fields, R field sandstones are richer in feldspar, pore-filling kaolinite and calcite, and lack recognizable volcanic rock fragments. Secondary porosity and chlorite in these sandstones are rare.

  14. Petrology and depositional environments of lower Tuscaloosa Formation (upper Cretaceous) sandstones in North Hustler and Thompson field areas, southwestern Mississippi

    SciTech Connect

    Klicman, D.P.; Cameron, C.P.; Meylan, M.A.

    1988-09-01

    The lithology, diagenesis, and depositional environments of the Dykes, Denkman, and McComb units of the Stringer Sand Member of the lower Tuscaloosa Formation in the North Hustler and Thompson field areas of Amite County, Mississippi, have been determined by detailed description of cores from nine wells and examination of 61 thin sections. The cores were recovered from driller depths of about 11,100 ft (3383 m) in the updip Tuscaloosa trend, which is being actively explored for stratigraphically trapped oil. Most of the sandstone samples (65%) are quartzarenites, and the remainder are sublitharenites. Porosity is mostly secondary, resulting from partial dissolution of framework grains and cement. The depositional environment of the Dykes and Denkman sandstones in all wells is interpreted to be fluvial, with stacked point bars obvious in one well. The McComb sandstone, best developed in a wildcat well between Thompson and McComb fields, is marine, based on the occurrence of glauconite and shell fragments. The presence of a basal scour surface on shale indicates that this sandstone may be the product of marine reworking of a transgressed fluvial (distributary point or mouth bar.)sand.

  15. Petrographic Evidence of Microbial Mats in the Upper Cretaceous Fish-Bearing, Organic-Rich Limestone, Agua Nueva Formation, Central Mexico

    NASA Astrophysics Data System (ADS)

    Blanco, A.; Maurrasse, F. J.; Hernández-Ávila, J.; Ángeles-Trigueros, S. A.; García-Cabrera, M. E.

    2013-05-01

    We document petrographic evidence of microbial mats in the Upper Cretaceous Agua Nueva Formation in the area of Xilitla (San Luis Potosí, Central Mexico), located in the southern part of the Tampico-Misantla basin. The sequence consists predominantly of alternating decimeter-thick beds of fossiliferous dark laminated limestone (C-org > 1.0wt%), and light gray, bioturbated limestone (C-org < 1.0wt%), with occasional brown shale and green bentonite layers. Well-preserved fossil-fish assemblages occur in the laminated dark limestone beds, which include shark teeth (cf. Ptychodus), scales of teleosteans (Ichthyodectiformes), as well as skeletal remains of holosteans (Nursallia. sp), and teleosteans (cf. Rhynchodercetis, Tselfatia, and unidentified Enchodontids). Thin section and SEM analyses of the laminated, dark limestones, reveal a micritic matrix consisting of dark and light sub-parallel wavy laminae, continuous and discontinuous folded laminae with shreds of organic matter, filaments, oncoids, and interlocking structures. The structures are identical to those previously described for the Cenomanian-Turonian Indidura Fm at Parras de la Fuente (Coahuila state) demonstrated to be of microbial origin (Duque-Botero and Maurrasse, 2005; 2008). These structures are also analogous to microbial mats in present environments, and Devonian deposits (Kremer, 2006). In addition, the laminae at Xilitla include filamentous bacterial structures, as thin and segmented red elements. In some thin sections, filaments appear to be embedded within the crinkly laminae and shreds showing the same pattern of folding, suggestive of biomorphic elements that represent the main producers of the organic matter associated with the laminae. Thus, exceptional bacterial activity characterizes sedimentation during the accumulation of the Agua Nueva Formation. Oxygen-deficient conditions related to the microbial mats were an important element in the mass mortality and preservation of the fish

  16. Seismic expression of subtle strat trap in Upper Cretaceous Almond

    USGS Publications Warehouse

    Ryder, Robert T.; Lee, Myung W.; Agena, Warren F.; Anderson, Robert C.

    1990-01-01

    The east flank of the Rock Springs uplift and the adjacent Wamsutter arch contain several large hydrocarbon accumulations. Among these accumulations are Patrick Draw field, which produces oil and gas from a stratigraphic trap in the Upper Cretaceous Almond formation, and Table Rock field, a faulted anticlinal trap that produces gas from multiple Tertiary, Mesozoic, and Paleozoic reservoirs. The principal petroleum reservoir in Patrick Draw field is a sandstone at the top of the Almond formation. This sandstone attains a maximum thickness of 35ft and piches out westward into relatively impervious silt-stone and shale that constitute the trapping facies. The objective of this investigation is to determine whether or not the stratigraphic trap at Patrick Draw can be detected on a 12 fold, common depth point seismic profile acquired by Forest Oil Corp. and its partners. The seismic line is 18.5 miles long and crosses Patrick Draw and Table Rock fields.

  17. Seismic expression of subtle strat trap in upper Cretaceous Almond

    SciTech Connect

    Ryder, R.T. ); Lee, M.W.; Agena, W.F. ); Anderson, R.C. )

    1990-12-17

    The east flank of the Rock Springs uplift and the adjacent Wamsutter arch contain several large hydrocarbon accumulations. Among these accumulations are Patrick Draw field, which produces oil and gas from a stratigraphic trap in the upper Cretaceous Almond formation, and Table Rock field, a faulted anticlinal trap that produces gas from multiple Tertiary, Mesozoic, and Paleozoic reservoirs. The principal petroleum reservoir in Patrick Draw field is a sandstone at the top of the Almond formation. This sandstone attains a maximum thickness of 35 ft (11 m) and pinches out westward into relatively impervious siltstone and shale that constitute the trapping facies. The objective of this investigation is to determine whether or not the stratigraphic trap at Patrick Draw can be detected on a 12 fold, common depth point seismic profile.

  18. Composition and provenance of placer deposits in McCourt Tongue of Rock Springs Formation (Upper Cretaceous), Rock Springs uplift area, Wyoming

    SciTech Connect

    Schneider, G.B.

    1986-08-01

    Heavy minerals from placer sandstones were studied from samples collected at five widely spaced outcrops of the McCourt Tongue on the southeastern flank of the Rock Springs uplift and on the northern flank of the Uinta Mountains. The placers were deposited along a northeast-trending, strand-plain shoreline of the Cretaceous Interior seaway. Heavy minerals from the five localities occur in very fine-grained sandstone and are composed of about 85% opaque iron and titanium minerals, including magnetite, hematite, and ilmenite. About 15% consist of nonopaque minerals, which are mostly zircon, garnet, tourmaline, and rutile with minor amounts of sphene, hornblende, and apatite. The cementing material is mostly hematite. The nonopaque suite is as much as 96% zircon grains, with 3/sup 0/ of roundness and five color varieties. The heavy minerals are from both plutonic and volcanic source areas. The plutonic minerals suggest a westerly source in Precambrian rocks of Utah and Idaho. The volcanic minerals were probably derived from areas of volcanic activity in Alberta and Montana. The composition, distribution, and provenance of the deposits help establish a framework for regressive Upper Cretaceous shorelines in the central Rocky Mountain area.

  19. A giant sauropod dinosaur from an Upper Cretaceous mangrove deposit in Egypt.

    PubMed

    Smith, J B; Lamanna, M C; Lacovara, K J; Dodson, P; Smith, J R; Poole, J C; Giegengack, R; Attia, Y

    2001-06-01

    We describe a giant titanosaurid sauropod dinosaur discovered in coastal deposits in the Upper Cretaceous Bahariya Formation of Egypt, a unit that has produced three Tyrannosaurus-sized theropods and numerous other vertebrate taxa. Paralititan stromeri is the first tetrapod reported from Bahariya since 1935. Its 1.69-meter-long humerus is longer than that of any known Cretaceous sauropod. The autochthonous scavenged skeleton was preserved in mangrove deposits, raising the possibility that titanosaurids and their predators habitually entered such environments.

  20. Origin of crude oil in eastern Gulf Coast: Upper Jurassic, Upper Cretaceous, and lower Tertiary source rocks

    SciTech Connect

    Sassen, R.

    1988-02-01

    Analysis of rock and crude oil samples suggests that three source rocks have given rise to most crude oil in reservoirs of the eastern Gulf Coast. Carbonate source rocks of the Jurassic Smackover Formation are characterized by algal-derived kerogen preserved in an anoxic and hypersaline environment, resulting in crude oils with distinct compositions. Migration commenced during the Cretaceous, explaining the emplacement of Smackover-derived crude oil in Jurassic and in some Cretaceous reservoirs. Upper Cretaceous clastic and carbonate source rocks are also present. Much crude oil in Upper Cretaceous reservoirs has been derived from organic-rich marine shales of the Tuscaloosa Formation. These shales are characterized by algal and higher plant kerogen, resulting in distinct crude oil compositions. Migration commenced during the Tertiary, but was mostly focused to Upper Cretaceous reservoirs. Lower Tertiary shales, including those of the Wilcox Formation, are quite organic-rich and include downdip marine facies characterized by both algal and higher plant kerogen. Crude oils in lower Tertiary reservoirs are dissimilar to crude oils from deeper and older source rocks. Migration from lower Tertiary shales commenced during the late Tertiary and charged Tertiary reservoirs. Although most crude oil in the eastern Gulf Coast has been emplaced by short-range migration, often with a strong vertical component, some long-range lateral migration (> 100 km) has occurred along lower Tertiary sands. The framework of crude oil generation and migration onshore has important implications with respect to origin of crude oil in the Gulf of Mexico.

  1. Anatomy and Taxonomic Status of the Chasmosaurine Ceratopsid Nedoceratops hatcheri from the Upper Cretaceous Lance Formation of Wyoming, U.S.A

    PubMed Central

    Farke, Andrew A.

    2011-01-01

    Background The validity of Nedoceratops hatcheri, a chasmosaurine ceratopsid dinosaur known from a single skull recovered in the Lance Formation of eastern Wyoming, U.S.A., has been debated for over a century. Some have argued that the taxon is an aberrant Triceratops, and most recently it was proposed that N. hatcheri represents an intermediate ontogenetic stage between “young adult” and “old adult” forms of a single taxon previously split into Triceratops and Torosaurus. Methodology/Principal Findings The holotype skull of Nedoceratops hatcheri was reexamined in order to map reconstructed areas and compare the specimen with other ceratopsids. Although squamosal fenestrae are almost certainly not of taxonomic significance, some other features are unique to N. hatcheri. These include a nasal lacking a recognizable horn, nearly vertical postorbital horncores, and relatively small parietal fenestrae. Thus, N. hatcheri is tentatively considered valid, and closely related to Triceratops spp. The holotype of N. hatcheri probably represents an “old adult,” based upon bone surface texture and the shape of the horns and epiossifications on the frill. In this study, Torosaurus is maintained as a genus distinct from Triceratops and Nedoceratops. Synonymy of the three genera as ontogenetic stages of a single taxon would require cranial changes otherwise unknown in ceratopsids, including additions of ossifications to the frill and repeated alternation of bone surface texture between juvenile and adult morphotypes. Conclusions/Significance Triceratops, Torosaurus, and likely Nedoceratops, are all distinct taxa, indicating that species richness for chasmosaurine ceratopsids in the Lance Formation just prior to the Cretaceous-Paleocene extinction was roughly equivalent to that earlier in the Cretaceous. PMID:21283763

  2. Carbon isotope stratigraphy of the upper Kharaib and Shuaiba formations: Implications for the Early Cretaceous evolution of the Arabian Gulf Region

    SciTech Connect

    Vahrenkamp, V.C.

    1996-05-01

    The carbon isotope profiles of shallow-marine carbonates from the Barremian-Aptian Kharaib and Shuaiba formations of the Arabian Gulf region range between 0.5 and 7{per_thousand} {delta}{sup 13}C PDB (Peedee belemnite). Systematic variations can be correlated with isotope profiles reported from Tethyan pelagic limestone sequences. The detailed correspondence between the isotopic signature of the relatively well-dated pelagic limestones and the poorly dated shallow-water limestones from the Arabian Gulf region suggests that global marine carbon isotope changes apparently affected deep-sea and shallow-water carbonate sediments similarly and at a similar time resolution. Although oxygen isotopes have been reset during diagenesis, carbon isotopes appear to have maintained their primary marine signature through time. No evidence has been found to connect carbon isotope trends to subaerial exposure or later meteoric diagenesis. In combination with other data, the investigated carbon isotope profiles can be used for basin-to-platform and regional correlations beyond the current resolution of biostratigraphy in shallow-water limestones. Carbon isotope stratigraphy confirms significant hiatuses in the investigated shallow-water carbonate sequences. Using carbon isotope trends as a proxy for sea level fluctuations, the carbon isotope cycles of the late Early Cretaceous of the Arabian Gulf region may represent four cycles of rising and falling sea level with a duration corresponding to that of third-order sea level fluctuations. Regional correlations derived from isotope trends provide a scenario for the larger scale stratigraphic evolution of the Arabian peninsula during the end of the Early Cretaceous.

  3. Extensional tectonic influence on lower and upper cretaceous stratigraphy and reservoirs, southern Powder River basin, Wyoming

    SciTech Connect

    Mitchell, G.C.; Rogers, M.H.

    1993-04-01

    The southern Powder River basin has been influenced significantly by an extensional system affecting Lower Cretaceous, Upper Cretaceous and Tertiary units. The system is composed of small throw, nearly vertical normal faults which are identified in the Cretaceous marine shales and that we believe are basement derived. Resultant fractures were present at erosional/depositional surfaces, both marine and nonmarine, that, in part, controlled erosion and subsequent deposition of Lower and Upper Cretaceous rocks. The normal faults also affected coal deposition in the Tertiary, now exposed at the surface. The erosion and resultant deposition formed extensive stratigraphic traps in Cretaceous units in both conventional and unconventional reservoirs. These reservoirs are interbedded with mature source rocks that have generated and expelled large amounts of hydrocarbons. Resulting overpressuring in the Fall River through the Niobrara formations has kept fractures open and has preserved primary porosity in the reservoirs. The normal faults offset thin sandstone reservoirs forming permeability barriers. Associated fractures may have provided vertical pathways for organic acids that assisted development of secondary porosity in Upper Cretaceous sandstones. These normal...faults and fractures provide significant potential for the use of horizontal drilling techniques to evaluate fractured, overpressured conventional and unconventional reservoirs.

  4. First planktonic foraminifera from the Early Cretaceous (Albian) of the Upper Magdalena Valley, Colombia

    NASA Astrophysics Data System (ADS)

    Blau, J.; Vergara, L.; Stock, H. W.

    1992-10-01

    Albian planktonic foraminifera have been found in the Caballos and "Villeta" formations at two localities in the Upper Magdalena Valley. This is the first documented record of Early Cretaceous planktonic foraminifera in Colombia. Hedbergellids and heterohelicids predominate; keeled forms are absent. The sedimentologic features and the associated microfauna indicate the onset of restricted environments from the middle Albian on.

  5. Upper Cretaceous and lower Eocene conglomerates of Western Transverse Ranges: evidence for tectonic rotation

    SciTech Connect

    Reed, W.E.; Krause, R.G.F.

    1989-04-01

    Stratigraphic and paleomagnetic studies have suggested that the western Transverse Ranges (WTR) microplate is allochthonous, and may have experienced translational and rotational motions. Present paleocurrent directions from the Upper Cretaceous Jalama Formation of the Santa Ynez Mountains are north-directed; these forearc sediments (Great Valley sequence) contain magmatic arc-derived conglomerate clasts from the Peninsular Ranges in southern California. Paleocurrents in the lower Eocene Juncal and Cozy Dell Formations are south-directed. This juxtaposition is best explained by 90/degrees/ or more of clockwise rotation of the WTR microplate, so that Upper Cretaceous forearc sediments sourced from the Peninsular Ranges magmatic arc were deposited by west-directed currents. Eocene sediments were derived from an uplifted portion of the western basin margin and deposited by east-directed currents. Franciscan olistoliths in the Upper Cretaceous sediments indicate deposition adjacent to an accretionary wedge; conglomeratic clasts recycled from the Upper Cretaceous sequence, and radiolarian cherts and ophiolitic boulders in the Eocene strata indicate derivation from an outer accretionary ridge.

  6. Spiclypeus shipporum gen. et sp. nov., a Boldly Audacious New Chasmosaurine Ceratopsid (Dinosauria: Ornithischia) from the Judith River Formation (Upper Cretaceous: Campanian) of Montana, USA.

    PubMed

    Mallon, Jordan C; Ott, Christopher J; Larson, Peter L; Iuliano, Edward M; Evans, David C

    2016-01-01

    This study reports on a new ceratopsid, Spiclypeus shipporum gen et sp. nov., from the lower Coal Ridge Member of the Judith River Formation in Montana, USA, which dates to ~76 Ma (upper Campanian). The species is distinguished by rugose dorsal contacts on the premaxillae for the nasals, laterally projecting postorbital horncores, fully fused and anteriorly curled P1 and P2 epiparietals, and a posterodorsally projecting P3 epiparietal. The holotype specimen is also notable for its pathological left squamosal and humerus, which show varied signs of osteomyelitis and osteoarthritis. Although the postorbital horncores of Spiclypeus closely resemble those of the contemporaneous 'Ceratops', the horncores of both genera are nevertheless indistinguishable from those of some other horned dinosaurs, including Albertaceratops and Kosmoceratops; 'Ceratops' is therefore maintained as a nomen dubium. Cladistic analysis recovers Spiclypeus as the sister taxon to the clade Vagaceratops + Kosmoceratops, and appears transitional in the morphology of its epiparietals. The discovery of Spiclypeus adds to the poorly known dinosaur fauna of the Judith River Formation, and suggests faunal turnover within the formation. PMID:27191389

  7. Spiclypeus shipporum gen. et sp. nov., a Boldly Audacious New Chasmosaurine Ceratopsid (Dinosauria: Ornithischia) from the Judith River Formation (Upper Cretaceous: Campanian) of Montana, USA

    PubMed Central

    Mallon, Jordan C.; Ott, Christopher J.; Larson, Peter L.; Iuliano, Edward M.; Evans, David C.

    2016-01-01

    This study reports on a new ceratopsid, Spiclypeus shipporum gen et sp. nov., from the lower Coal Ridge Member of the Judith River Formation in Montana, USA, which dates to ~76 Ma (upper Campanian). The species is distinguished by rugose dorsal contacts on the premaxillae for the nasals, laterally projecting postorbital horncores, fully fused and anteriorly curled P1 and P2 epiparietals, and a posterodorsally projecting P3 epiparietal. The holotype specimen is also notable for its pathological left squamosal and humerus, which show varied signs of osteomyelitis and osteoarthritis. Although the postorbital horncores of Spiclypeus closely resemble those of the contemporaneous ‘Ceratops’, the horncores of both genera are nevertheless indistinguishable from those of some other horned dinosaurs, including Albertaceratops and Kosmoceratops; ‘Ceratops’ is therefore maintained as a nomen dubium. Cladistic analysis recovers Spiclypeus as the sister taxon to the clade Vagaceratops + Kosmoceratops, and appears transitional in the morphology of its epiparietals. The discovery of Spiclypeus adds to the poorly known dinosaur fauna of the Judith River Formation, and suggests faunal turnover within the formation. PMID:27191389

  8. Tectonic development of Upper Cretaceous to Eocene strata of southwestern Utah

    SciTech Connect

    Goldstrand, P.M. )

    1994-01-01

    Upper Cretaceous to Paleogene nonmarine sedimentary rocks of southwest Utah record Sevier foreland basin sedimentation, Laramide-style folding and intermontane sedimentation, and cessation of Laramide deformation. The formations that record this tectonic evolution arc, from oldest to youngest, the Iron Springs, Kaiparowits, Canaan Peak, Grand Castle (informal name), Pine Hollow, and basal part of the Claron. The upper part of the Santonian to lower Campanian( ) Iron Springs Formation represents synorogenic, fluvial deposits derived from the Wah Wah and Blue Mountain thrust sheets of southwestern Utah. The middle to upper Campanian Kaiparowits and upper Campanian( ) to lower Paleocene Canaan Peak Formations are an upward-coarsening sequence derived from southeastern California and southern Nevada. Initial Laramide-style deformation occurred during latest Cretaceous or early Paleocene time, influencing the depositional pattern of the Canaan Peak fluvial system. The lower Paleocene Grand Castle formation represents an east- to southeast-flowing, braided-river system with the same source as the Iron Springs Formation (the Wah Wah and Blue Mountain thrust sheets). Conglomerate of Grand Castle onlaps the easternmost Sevier thrusts and is folded by Laramide structures. Although strata of the Grand Castle formation represent post-thrust and, in part, pre-Laramide deposition, initial development of a south-southwest-trending, Laramide-style upwarp controlled the geometry of the Grand Castle basin. 55 refs., 11 figs.

  9. Sequence stratigraphic controls on synsedimentary cementation and preservation of dinosaur tracks: Example from the lower Cretaceous, (Upper Albian) Dakota Formation, Southeastern Nebraska, U.S.A.

    USGS Publications Warehouse

    Phillips, P.L.; Ludvigson, Greg A.; Matthew, Joeckel R.; Gonzalez, Luis A.; Brenner, Richard L.; Witzke, B.J.

    2007-01-01

    A thin cemented sandstone bed in the Upper Albian Dakota Formation of southeastern Nebraska contains the first dinosaur tracks to be described from the state. Of equal importance to the tracks are stable-isotope (C, O) analyses of cements in the track bed, especially in the context of data derived from generally correlative strata (sandstones and sphaerosiderite-bearing paleosols) in the region. These data provide the framework for interpretations of paleoenvironmental conditions, as well as a novel approach to understanding mechanisms of terrestrial vertebrate track preservation. High minus-cement-porosity (> 47%) and low grain-to-grain contacts (???2.5) in the track bed indicate early (pre-compaction) lithification. Although phreatic cements dominate, the history of cementation within this stratigraphic interval is complex. Cathodoluminescence petrography reveals two distinct calcite zones in the track-bearing horizon and four cement zones in stratigraphically equivalent strata from a nearby section. The earliest calcite cements from both localities are likely coeval because they exhibit identical positive covariant trends (??18O values of - 9.89 to - 6.32??? and ??13C values of - 28.01 to - 19.33??? VPDB) and record mixing of brackish and meteoric groundwaters. All other calcite cements define meteoric calcite lines with ??18O values clustering around - 9.42??? and - 8.21??? VPDB from the track-bearing horizon, and - 7.74???, - 5.81???, and - 3.95??? VPDB from the neighboring section. Distinct meteoric sphaerosiderite lines from roughly correlative paleosols serve as a proxy for locally recharged groundwaters. Back-calculated paleogroundwater ??18O estimates from paleosol sphaerosiderites range from - 7.4 to - 4.2??? SMOW; whereas, meteoric calcite lines from the track horizon are generally more depleted. Differences in cement ??18O values record changes in paleogroundwater recharge areas over time. Early calcite cements indicate mixing of fresh and brackish

  10. Stratigraphic framework of Lower and Upper Cretaceous rocks in central and eastern Montana

    USGS Publications Warehouse

    Condon, Steven M.

    2000-01-01

    This study shows the lithology, thickness, distribution, and correlation of Lower and Upper Cretaceous rocks in central and eastern Montana. The described stratigraphic units range from the Aptian Kootenai Formation (oldest) to the Maastrichtian Hell Creek Formation (youngest). An included text report describes the units, and most formations or members are also represented by isopach maps. Structure contour maps of three horizons are also included. Correlations across the study area are shown on a series of cross sections. All text and illustrations are included as Adobe PDF files.

  11. Using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) to explore geochemical taphonomy of vertebrate fossils in the upper cretaceous two medicine and Judith River formations of Montana

    USGS Publications Warehouse

    Rogers, R.R.; Fricke, H.C.; Addona, V.; Canavan, R.R.; Dwyer, C.N.; Harwood, C.L.; Koenig, A.E.; Murray, R.; Thole, J.T.; Williams, J.

    2010-01-01

    Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) was used to determine rare earth element (REE) content of 76 fossil bones collected from the Upper Cretaceous (Campanian) Two Medicine (TMF) and Judith River (JRF) Formations of Montana. REE content is distinctive at the formation scale, with TMF samples exhibiting generally higher overall REE content and greater variability in REE enrichment than JRF samples. Moreover, JRF bones exhibit relative enrichment in heavy REE, whereas TMF bones span heavy and light enrichment fields in roughly equal proportions. TMF bones are also characterized by more negative Ce anomalies and greater U enrichment than JRF bones, which is consistent with more oxidizing diagenetic conditions in the TMF. Bonebeds in both formations show general consistency in REE content, with no indication of spatial or temporal mixing within sites. Previous studies, however, suggest that the bonebeds in question are attritional assemblages that accumulated over considerable time spans. The absence of geochemical evidence for mixing is consistent with diagenesis transpiring in settings that remained chemically and hydrologically stable during recrystallization. Lithology-related patterns in REE content were also compared, and TMF bones recovered from fluvial sandstones show relative enrichment in heavy REE when compared with bones recovered from fine-grained floodplain deposits. In contrast, JRF bones, regardless of lithologic context (sandstone versus mudstone), exhibit similar patterns of REE uptake. This result is consistent with previous reconstructions that suggest that channel-hosted microfossil bonebeds of the JRF developed via the reworking of preexisting concentrations embedded in the interfluve. Geochemical data further indicate that reworked elements were potentially delivered to channels in a recrystallized condition, which is consistent with rapid adsorption of REE postmortem. Copyright ?? 2010, SEPM (Society for

  12. Late Cretaceous biostratigraphy of the La Luna Formation, Maracaibo basin

    SciTech Connect

    Truskowski, I.; Galeaalvarez, F.; Sliter, W.V.

    1996-08-01

    Micropaleontological analysis, sedimentological studies, and geochemical data are presented for the Upper Cretaceous {open_quote}black shales{close_quote} of the La Luna Formation of Western Venezuela. The detailed planktonic foraminiferal studies allowed the establishment of the first biozonation, determination of sedimentation rates, and documentation of occurrences of benthic foraminifers for these unusually thick black shales that extend stratigraphically nearly 100 m. Hedbergellids, whiteinellids and Heterohelix characterize the lower part of the La Luna Formation, dated from the late Cenomanian Rotalipora cushmani Zone to middle Turonian Helvetoglobotruncana belvetica Zone. The high productivity of these groups associated with phosphatized fish remains suggest upwelling and a poorly stratified water column. The presence of buliminids and Favreina sp. at some levels, imply disoxic conditions in this anoxic interval. Planktonic foraminifers in the middle and upper parts of the formation range in age from the late Turonian Marginotruncana sigali- Dicarinella primitiva Zone to the early Campanian Globotruncanita elevata Zone. The increase in keeled planktonic foraminifers toward the top of the formation suggest more stratified, oligotrophic surface waters. Benthic foraminifers found at the top are indicative of dysaerobic conditions. This study provides new opportunities for utilizing the petroleum system in the La Luna Formation, arguably the most prolific source rock in northern South America.

  13. A New Ankylosaurid Dinosaur from the Upper Cretaceous (Kirtlandian) of New Mexico with Implications for Ankylosaurid Diversity in the Upper Cretaceous of Western North America

    PubMed Central

    Arbour, Victoria M.; Burns, Michael E.; Sullivan, Robert M.; Lucas, Spencer G.; Cantrell, Amanda K.; Fry, Joshua; Suazo, Thomas L.

    2014-01-01

    A new ankylosaurid (Ankylosauria: Dinosauria), Ziapelta sanjuanensis, gen. et sp. nov., is based on a complete skull, an incomplete first cervical half ring, a possible fragment of the second cervical half ring, and additional fragmentary osteoderms. The holotype specimen is from the Upper Cretaceous (Upper Campanian, Kirtlandian Land-Vertebrate Age) Kirtland Formation (De-na-zin Member) at Hunter Wash, San Juan Basin, in northwestern New Mexico, USA. Diagnostic characters of Ziapelta include: a large, prominent triangular median nasal caputegulum; a mixture of flat and bulbous frontonasal caputegulae; ventrolaterally oriented squamosal horns with a sharp, prominent dorsal keel; and the ventral surface of basicranium with three prominent anteroposteriorly oriented fossae. A phylogenetic analysis suggests that Ziapelta is not closely related to the other ankylosaurid from the De-na-zin Member, Nodocephalosaurus, but allies it to the northern North American ankylosaurids Ankylosaurus, Anodontosaurus, Euoplocephalus, Dyoplosaurus, and Scolosaurus. PMID:25250819

  14. Geologic Map of Upper Cretaceous and Tertiary Strata and Coal Stratigraphy of the Paleocene Fort Union Formation, Rawlins-Little Snake River Area, South-Central Wyoming

    USGS Publications Warehouse

    Hettinger, R.D.; Honey, J.G.; Ellis, M.S.; Barclay, C.S.V.; East, J.A.

    2008-01-01

    This report provides a map and detailed descriptions of geologic formations for a 1,250 square mile region in the Rawlins-Little Snake River coal field in the eastern part of the Washakie and Great Divide Basins of south-central Wyoming. Mapping of geologic formations and coal beds was conducted at a scale of 1:24,000 and compiled at a scale of 1:100,000. Emphasis was placed on coal-bearing strata of the China Butte and Overland Members of the Paleocene Fort Union Formation. Surface stratigraphic sections were measured and described and well logs were examined to determine the lateral continuity of individual coal beds; the coal-bed stratigraphy is shown on correlation diagrams. A structure contour and overburden map constructed on the uppermost coal bed in the China Butte Member is also provided.

  15. Assessment of undiscovered oil and gas resources of the Upper Cretaceous Austin Chalk and Tokio and Eutaw Formations, Gulf Coast, 2010

    USGS Publications Warehouse

    Pearson, Krystal; Dubiel, R.F.; Pearson, O.N.; Pitman, J.K.

    2011-01-01

    Using a geology-based assessment methodology, the U.S. Geological Survey estimated means of 957 million barrels of undiscovered oil, 3.6 trillion cubic feet of undiscovered natural gas, and 363 million barrels of undiscovered natural gas liquids in the Austin Chalk and Tokio and Eutaw Formations in onshore lands and State waters of the Gulf Coast.

  16. Single-crystal {sup 40}Ar/{sup 39}Ar ages for rocks in the lower part of the frontier formation (Upper Cretaceous), Southwest Wyoming

    SciTech Connect

    M`Gonigle, J.W.; Holmes, C.W.; Dalrymple, G.B.

    1995-04-01

    Five tuff beds in a 150 m (490 ft) thick section within the nonmarine Chalk Creek Member of the Frontier Formation and one bentonite bed within the Allen Hollow Shale Member of the Frontier Formation were sampled for {sup 40}Ar/{sup 39}Ar dating at localities south of Kemmerer, Wyoming. The study area extends from Cumberland Gap northward for 15 km (9.3 mi) past Blason Gap, and includes units 5-43 and unit 91 of the reference section measured by Cobban and Reeside in 1952. The age of the tuff beds ranges from 96.6 {plus_minus} 0.3 to 93.6 {plus_minus} 0.3 Ma and confirms the inferred Cenomanian age of much of the Chalk Creek Member. Previously, the member`s age had been based solely on its stratigraphic position between the Albian-to-lower Cenomanian marine rocks for the Aspen Shale and the lower Turonian marine shales in the middle of the Frontier Formation. The age of biotite crystals from the bentonite in the Allen Hollow Member, 92.1 {plus_minus} 0.2 Ma, confirms the paleontologic Turonian age of the member.

  17. Physical stratigraphy and hydrostratigraphy of Upper Cretaceous and Paleocene sediments, Burke and Screven Counties, Georgia

    USGS Publications Warehouse

    Falls, W.F.; Baum, J.S.; Prowell, D.C.

    1997-01-01

    Six geologic units are recognized in the Cretaceous and the Paleocene sediments of eastern Burke and Screven Counties in Georgia on the basis of lithologic, geophysical, and paleontologic data collected from three continuously cored testholes in Georgia and one testhole in South Carolina. The six geologic units are separated by regional unconformities and are designated from oldest to youngest as the Cape Fear Formation, the Middendorf Formation, the Black Creek Group (undivided), and the Steel Creek Formation in the Upper Cretaceous section, and the Ellenton and the Snapp Formations in the Paleocene section. The geologic units provide a spatial and temporal framework for the identification and correlation of a basal confining unit beneath the Midville aquifer system and five aquifers and five confining units in the Dublin and the Midville aquifer systems. The Dublin aquifer system is divided hydrostratigraphically into the Millers Pond, the upper Dublin, and the lower Dublin aquifers. The Midville aquifer system is divided hydrostratigraphically into the upper and the lower Midville aquifers. The fine-grained sediments of the Millers Pond, the lower Dublin, and the lower Midville confining units are nonmarine deposits and are present in the upper part of the Snapp Formation, the Black Creek Group (undivided), and the Middendorf Formation, respectively. Hydrologic data for specific sets of monitoring wells at the Savannah River Site in South Carolina and the Millers Pond site in Georgia confirm that these three units are leaky confining units and locally impede vertical ground-water flow between adjacent aquifers. The fine-grained sediments of the upper Dublin and the upper Midville confining units are marine-deltaic deposits of the Ellenton Formation and the Black Creek Group (undivided), respectively. Hydrologic data confirm that the upper Dublin confining unit regionally impedes vertical ground-water flow on both sides of the Savannah River. The upper Midville

  18. Hydrology of the Upper Cretaceous Fruitland Formation and the producibility of coal-bed methane, San Juan basin, Colorado and New Mexico

    SciTech Connect

    Kaiser, W.R. ); Swartz, T.E. )

    1990-05-01

    Fruitland coal seams contain 49 tcf of methane, which is produced from abnormally pressured coals in a variety of hydrologic settings. In a study funded by the Gas Research Institute, the authors calculated bottom-hole pressures from wellhead shut-in pressures to map hydraulic head and pressure regime, and estimated vertical pressure gradients to evaluate Fruitland hydrology and its relation to methane producibility. They inferred relative permeability from hydraulic head, pressure regime, and hydrochemistry, and related these hydrologic elements to established production. In the Fruitland Formation, coal seams are the primary aquifers, receiving recharge mainly from the elevated, wet, north and northwest margins of the basin. Formation waters in the north-central part of the basin have low chlorinities and high alkalinities, whereas those in the southern part of the basin are saline Na-Cl type similar to seawater. Regional discharge is to the San Juan River valley in the western part of the basin. Overpressuring in the north-central part of the basin is explained hydrodynamically and is attributed to artesian conditions. They infer enhanced coal-bed permeability where the potentiometric surface is flat and reduced permeability where it is steep. Overpressuring indicates enhanced permeability because permeability in coal seams is stress dependent. In the overpressured region, groundwater is fresh, indicative of an active, dynamic flow system and of permeable pathways. In contrast, connate seawater in the underpressured southern part of the basin implies negligible permeability; strata are too tight to accept and transmit measurable recharge. The basin's most productive coal bed-methane wells are overpressured and occur at hydrologic transitions from a flat to a steep potentiometric surface, overpressuring to underpressuring, and low- to high-chloride formation waters.

  19. Extreme Cranial Ontogeny in the Upper Cretaceous Dinosaur Pachycephalosaurus

    PubMed Central

    Horner, John R.; Goodwin, Mark B.

    2009-01-01

    Background Extended neoteny and late stage allometric growth increase morphological disparity between growth stages in at least some dinosaurs. Coupled with relatively low dinosaur density in the Upper Cretaceous of North America, ontogenetic transformational representatives are often difficult to distinguish. For example, many hadrosaurids previously reported to represent relatively small lambeosaurine species were demonstrated to be juveniles of the larger taxa. Marginocephalians (pachycephalosaurids + ceratopsids) undergo comparable and extreme cranial morphological change during ontogeny. Methodology/Principal Findings Cranial histology, morphology and computer tomography reveal patterns of internal skull development that show the purported diagnostic characters for the pachycephalosaurids Dracorex hogwartsia and Stygimoloch spinifer are ontogenetically derived features. Coronal histological sections of the frontoparietal dome of an adult Pachycephalosaurus wyomingensis reveal a dense structure composed of metaplastic bone with a variety of extremely fibrous and acellular tissue. Coronal histological sections and computer tomography of a skull and frontoparietal dome of Stygimoloch spinifer reveal an open intrafrontal suture indicative of a subadult stage of development. These dinosaurs employed metaplasia to rapidly grow and change the size and shape of their horns, cranial ornaments and frontoparietal domes, resulting in extreme cranial alterations during late stages of growth. We propose that Dracorex hogwartsia, Stygimoloch spinifer and Pachycephalosaurus wyomingensis are the same taxon and represent an ontogenetic series united by shared morphology and increasing skull length. Conclusions/Significance Dracorex hogwartsia (juvenile) and Stygimoloch spinifer (subadult) are reinterpreted as younger growth stages of Pachycephalosaurus wyomingensis (adult). This synonymy reduces the number of pachycephalosaurid taxa from the Upper Cretaceous of North America

  20. Tylerianthus crossmanensis gen. et sp. nov. (aff. Hydrangeaceae) from the Upper Cretaceous of New Jersey.

    PubMed

    Gandolfo, M; Nixon, K; Crepet, W

    1998-03-01

    A fossil flower with affinities to the modern families of the saxifragalean complex is described. Fossils were collected at Old Crossman Pit, Raritan Formation, New Jersey, USA. These sediments are dated on the basis of palynology as Turonian (Upper Cretaceous, ~90 million years before present). Fossils are charcoalified and preserved with exceptional three- dimensional detail. The characters observed in these flowers, when compared with those of extant flowers of several families of the saxifragalean complex, suggest a close relationship with extant members of the Saxifragaceae and Hydrangeaceae. Hypotheses on the origin of petals and staminodes and a possible mechanism of pollination are discussed. This new taxon provides additional characters in the floral morphology of the fossil saxifragoids and extends their geographical distribution in the Cretaceous to North America.

  1. Cyanobacteria/Foraminifera Association from Anoxic/Dysoxic Beds of the Agua Nueva Formation (Upper Cretaceous - Cenomanian/Turonian) at Xilitla, San Luis Potosi, Central Mexico

    NASA Astrophysics Data System (ADS)

    Blanco-Piñón, A.; Maurrasse, F. J.; Rojas-León, A.; Duque-Botero, F.

    2008-05-01

    The Agua Nueva Formation in the vicinity of Xilitla, State of San Luis Potosí, Central Mexico, consists of interbedded brown shale (Grayish orange 10YR 7/4 to Moderate yellowish brown 10YR 5/4) and dark-gray fossiliferous limestone (Bluish gray 5B 6/1 to Dark bluish gray 5B 4/1), varying between 10 and 20 cm in thickness. The sequence also includes 2 to 4 cm- thick intermittent bentonite layers (Moderate greenish yellow 10Y 7/4, to dark greenish yellow 10Y 6/6 and Light olive 10Y 5/4). At the field scale, shaly intervals show no apparent internal structures, whereas most limestone beds show primary lamination at the millimeter scale (1-2 mm), and intermittent layers of black chert of about 5 cm thick. Pyrite is present as disseminated crystals and as 2 cm-thick layers. Bioturbation or macrobenthic organisms other than inoceramids do not occur in the Agua Nueva Formation at Xilitla. Unusual macrofossils are present only in limestone strata, and consist of well- preserved diverse genera of fishes such as sharks, Ptychodus sp. and teleosteans, Rhynchodercetis sp., Tselfatia sp., Goulmimichthys sp., and scales of Ichtyodectiformes, as well as ammonites and inoceramids (Blanco et al., 2006). The presence of Inoceramus (Mytyloides) labiatus (Maldonado-Koederll, 1956) indicates an Early Turonian age for the sequence. Total carbonate content (CaCO3 = TIC) varies between 62 and 94% in the Limestone beds, which yield Total Organic Carbon (TOC) from 0.4% to 2.5%; the shale intervals contain TIC values consistently lower than 33% and TOC lower than 0.8% Microscopically the limestone beds vary from mudstone to packstone composed essentially of coccoid cyanobacteria similar to coeval deposits in northeastern Mexico, Coahuila State, at Parras de La Fuente (Duque- Botero 2006). Similarly, the microspheroids are spherical to sub-spherical, and occur as isolated elements or aggregates forming series of chains of parallel-packed light lamina 1-2 mm thick. Filamentous cyanobacteria

  2. Traces of evaporites in Upper Cretaceous lacustrine deposits of Korea: Origin and paleoenvironmental implications

    NASA Astrophysics Data System (ADS)

    Paik, In Sung; Huh, Min; So, Yoon Hwan; Lee, Jeong Eun; Kim, Hyun Joo

    2007-04-01

    Diverse types of halite and sulfate evaporite traces occur in the Upper Cretaceous lacustrine deposits of the Jindong Formation and the Jangdong Tuff in Korea, in which dinosaur tracks are common. The halite traces usually occur as casts or moulds, and they include traces of primary halite hoppers, primary and intrasedimentary skeletal halite, and intrasedimentary tiny halite. The sulfate traces occur as intrasedimentary and displacive casts filled with sediments and sparry calcite, and the casts occur as diverse modes from single crystal casts through nodular aggregates to massive aggregates. Some aggregates of the sulfate casts are aligned in crack pattern, and selective occurrence of the laths in ripple troughs are observed. Soluble sulfate evaporite minerals such as gypsum, glauberite, or mirabilite are probable for the precursors of these traces. These halite and sulfate traces are interpreted to have been formed in a saline lake and mudflats. It is interpreted that meteoric water was responsible for the evaporite precipitation in the Jindong Lake and Jangdong Lake. Recycled brine produced by the repeated dissolution of evaporites might contribute to the evaporite precipitation in the paleo-Jindong Lake and the paleo-Jangdong Lake. The development of saline lake deposits in the Jindong Formation and the Jangdong Tuff suggests that the southern part of the Korean Peninsula remained an inland continental area during the Cretaceous resulting in semi-arid paleoclimatic condition due to an orographic effect by the location of the Korean Peninsula on continental margin in mid-latitude with topographic barriers during the Cretaceous. The occurrence of dinosaur tracks in the lake margin deposits of saline lake with frequent inflow of dilute meteoric water suggests that Upper Cretaceous dinosaurs inhabiting lakes on the Korean Peninsula might have drunken brackish water.

  3. Stratigraphy, foraminiferal assemblages and paleoenvironments in the Late Cretaceous of the Upper Magdalena Valley, Colombia (part I)

    NASA Astrophysics Data System (ADS)

    Vergara, Luis S.

    1997-03-01

    The present work focuses on the Cretaceous record (Middle Albian-Maastrichtian) of the Upper Magdalena Valley (UMV), with a scope that covers facies and biofacies. The nomenclatural scheme previously stated for the Girardot-Guataqui area is here extended and proposed for all the basin, the following fomational units being characterized in detail. The Hondita Formation (Middle Albian-late Turonian), placed on top of the Caballos Formation, is separated from the Lomagorda Formation (late Turonian-early Santonian) by a chert interval within a succession of predominantly dark shales deposited in outer shelf environments. The Olini Group (early Santonian-late Campanian) presents two conspicuous chert units (Lidita Inferior and Superior) overlain by the Nivel de Lutitas y Arenas (early Maastrichtian). The sandstones of La Tabla and finally the mudstones of the Seca Formation (Maastrichtian) represent diverse littoral environments of the end of the Cretaceous. In the UMV, the Cretaceous system attains approximately 1350 m of thickness. Within the paleogeographic scenario, the drowning of the basin and of the adjacent Central Cordillera during most of the Late Cretaceous enabled upwelling currents and the development of widespread pelagic sediments. These sediments graded to shallower water deposits towards the south of the basin. In the Upper Cretaceous, four sequences of second order can be identified. The longer cycle begins at the base of the Hondita Formation and exhibits the maximum flooding in the Cenomanian condensed section of this unit. Following this cycle, three successive sudden sea level drops mark the boundaries of complete sequences, each comprising well developed lowstand, transgressive and highstand system tracts. After the last cycle was completed, the basin was uplifted and rocks of the Seca Formation were cannibalized by fluvial processes during the Tertiary. An angular unconformity that truncates this unit represents the uppermost sequence boundary of

  4. Depth and thickness of selected units in Upper Permian, Upper Jurassic, and Lower Cretaceous rocks in southwestern Kansas

    USGS Publications Warehouse

    Kume, Jack; Spinazola, Joseph M.

    1984-01-01

    As ground-water reserves decline in the Ogallala aquifer in an area of about 17,400 square miles in 26 counties of southwestern Kansas, sandstone aquifers in underlying Upper Jurassic and Lower and Upper Cretaceous rocks may be developed to supplement or replace the Ogallala as a source of water for some uses. Maps show that depths from land surface to Upper Permian rocks range from 0 at the outcrop to over 2,100 feet, depths to Upper Jurassic rocks ran from 0 at the outcrop to about 2,000 feet, depths to the Cheyenne Sandstone range from about 150 to about 1 ,950 feet, and depths to the Dakota Formation range from 0 at the outcrop to about 1,650 feet. Additional maps show that the thickness of Upper Jurassic rocks, where present, ranges from less than 50 feet to about 250 feet, the thickness of the Cheyenne Sandstone, where present, ranges from about 20 feet to about 250 feet, and the thickness of the Dakota Formation, where present, ranges from about 60 feet to about 460 feet. (USGS)

  5. Reevaluation of upper Jurassic Morrison Formation, Western Interior

    SciTech Connect

    Mantzios, C.

    1989-03-01

    Comparison of the Brushy Basin member of the Upper Jurassic Morrison Formation in the Colorado Plateau with the Upper Jurassic-Lower Cretaceous Morrison-Cloverly sequence in the Bighorn basin, Wyoming, shows great similarities in their depositional environments and stratigraphy. The lower Brushy Basin member is a fluvial deposit composed of channel sandstones and overbank mudstones which display a great number of pedogenic features. Similar depositional setting has been observed in the Morrison Formation in the Bighorn basin, Wyoming, where pedogenic features suggest a distal floodplain setting with low-sinuosity channels cutting through. In both localities the dominant clay mineral is illite. The upper Brushy Basin member in the Colorado Plateau is composed mostly of gray and purpose mudstones rich in montmorillonite. Devitrified tuff beds and bentonite occur in certain levels throughout the unit. Pedogenic features are not conspicuously developed. The Lower Cretaceous Clovery Formation in the Bighorn basin, Wyoming, is strikingly similar in terms of lithological aspects. The depositional environment is interpreted in both localities as a playa deposit. A great variety of nodules is present such as silcretes, septaria, and silica-carbonate nodules. Radiometric dating of bentonites in central Utah revealed that the upper Brushy Basin member is Early Cretaceous in age. Field and geochemical data support these conclusions and aid the understanding of the exact nature of the depositional basin, environments, stratigraphy, and paleotectonics of the Upper Jurassic-Lower Cretaceous interval in the Western Interior.

  6. Upper cretaceous (Austin Group) volcanic deposits as a hydrocarbon trap

    SciTech Connect

    Hutchinson, P.J.

    1994-12-31

    An Upper Cretaceous submarine igneous extrusion occurs in the subsurface of southwestern Wilson County, Texas. The Coniacian-Santonian-aged (Austin Group) volcanic eruption discharged large volumes of magnetite-rich olivine nephelinite that upon quenching formed an extensive nontronitic clay layer. This clay deposit formed a trapping mechanism for hydrocarbon beneath the volcano. Production from volcanic plugs is normally attributed to the shoal-water carbonate facies developed on top of the volcanic, the palagonite tuff ({open_quotes}serpentine{close_quotes}), and overlying sandstones. The heat energy of the volcano may have thermally matured the calcarous sediments of adjacent parts of the Austin Chalk. The normally grayish-colored suggesting thermal alteration. The overlying nontronite trapped mobile hydrocarbons, and this early emplacement of oil may have preserved some of the original porosity and permeability of the Austin Chalk. Austin Chalk-aged volcanic deposits produce hydrocarbons from stratigraphic traps within the volcanic material, within the porous beachrock, and structurally within overlying sandstones. The intruded Austin Chalk also behaves as a reservoir because the original porosity and permeability are maintained by early emplacement of oil and the overlying volcanic clay acts as a seal by preventing vertical migration. Marcelina Creek field, discovered in 1980 from an {open_quotes}augen{close_quotes}-shaped seismic signature and an aerial magnetic survey, produces from the fractured chalk beneath the nontronitic clay layer. This field has produced more than 15 million barrels of oil from more than 60 wells in fractured and porous rock beneath the volcano.

  7. New crocodiles (Eusuchia: Alligatoroidea) from the Upper Cretaceous of southern Europe

    NASA Astrophysics Data System (ADS)

    Buscalioni, Angela D.; Ortega, Francisco; Vasse, Denis

    1997-10-01

    The Upper Cretaceous sites of Laño and Quintanilla del Coco in northern Spain have yielded significant crocodilian remains, allowing a more precise interpretation of the fragmentary record of southwestern Europe. Two new genera, Musturzabalsuchus and Acynodon, have been recognized. Both taxa were extinct at the end of the Cretaceous. Their relationships with the alligatoroidean Eusuchia suggest a close relationship with Paleolaurasian groups. Musturzabalsuchus might be regarded as an endemic european taxa, the oldest known member of the basal Alligatoroidea. Acynodon is the only non-North American taxon that is related to the short snouted Upper Cretaceous alligatorids.

  8. The bivalve Anopaea (Inoceramidae) from the Upper Jurassic-lowermost Cretaceous of Mexico

    NASA Astrophysics Data System (ADS)

    Zell, Patrick; Crame, J. Alistair; Stinnesbeck, Wolfgang; Beckmann, Seija

    2015-07-01

    In Mexico, the Upper Jurassic to lowermost Cretaceous La Casita and coeval La Caja and La Pimienta formations are well-known for their abundant and well-preserved marine vertebrates and invertebrates. The latter include conspicuous inoceramid bivalves of the genus Anopaea not formally described previously from Mexico. Anopaea bassei (Lecolle de Cantú, 1967), Anopaea cf. stoliczkai (Holdhaus, 1913), Anopaea cf. callistoensis Crame and Kelly, 1995 and Anopaea sp. are rare constituents in distinctive Tithonian-lower Berriasian levels of the La Caja Formation and one Tithonian horizon of the La Pimienta Formation. Anopaea bassei was previously documented from the Tithonian of central Mexico and Cuba, while most other members of Anopaea described here are only known from southern high latitudes. The Mexican assemblage also includes taxa which closely resemble Anopaea stoliczkai from the Tithonian of India, Indonesia and the Antarctic Peninsula, and Anopaea callistoensis from the late Tithonian to ?early Berriasian of the Antarctic Peninsula. Our new data expand the palaeogeographical distribution of the high latitude Anopaea to the Gulf of Mexico region and substantiate faunal exchange, in the Late Jurassic-earliest Cretaceous, between Mexico and the Antarctic Realm.

  9. Upper cretaceous microbial petroleum systems in north-central Montana

    USGS Publications Warehouse

    Lillis, Paul G.

    2007-01-01

    Methanogenesis began soon after the deposition (early-stage methanogenesis) of the Cenomanian to Campanian source sediments, and was either sustained or rejuvenated by episodic meteoric water influx until sometime in the Paleogene. Methanogenesis probably continued until CO2 and hydrogen were depleted or the pore size was compacted to below tolerance levels of the methanogens. The composition of the Montana and Colorado Group gases and coproduced formation water precludes a scenario of late-stage methanogenesis like the Antrim gas system in the Michigan basin. Some portion of the methane charge was originally dissolved in the pore waters, and subsequent reduction in hydrostatic pressure caused the methane to exsolve and migrate into local stratigraphic and structural traps. The critical moment of the microbial gas systems is this timing of exsolution rather than the time of generation (methanogenesis). Other studies suggest that the reduction in hydrostatic pressure may have been caused by multiple geologic events including the lowering of sea level in the Late Cretaceous, and subsequent uplift and erosion events, the youngest of which began about 5 Ma.

  10. Upper Cretaceous molluscan record along a transect from Virden, New Mexico, to Del Rio, Texas

    USGS Publications Warehouse

    Cobban, W.A.; Hook, S.C.; McKinney, K.C.

    2008-01-01

    Updated age assignments and new collections of molluscan fossils from lower Cenomanian through upper Campanian strata in Texas permit a much refined biostratigraphic correlation with the rocks of New Mexico and the Western Interior. Generic names of many Late Cretaceous ammonites and inoceramid bivalves from Texas are updated to permit this correlation. Strata correlated in the west-to-east transect include the lower Cenomanian Beartooth Quartzite and Sarten Sandstone of southwest New Mexico, and the Eagle Mountains Formation, Del Rio Clay, Buda Limestone, and. basal beds of the Chispa Summit, Ojinaga, and Boquillas Formations of the Texas-Mexico border area. Middle Cenomanian strata are lacking in southwestern New Mexico but are present in the lower parts of the Chispa Summit and Boquillas Formations in southwest Texas. Upper Cenomanian and lower Turonian rocks are present at many localities in New Mexico and Texas in the Mancos Shale and Chispa Summit, Ojinaga, and Boquillas Formations. Middle Turonian and younger rocks seem to be entirely nonmarine in southwestern New Mexico, but they are marine in the Rio Grande area in the Chispa. Summit, Ojinaga, and Boquillas Formations. The upper part of the Chispa Summit and Boquillas contain late Turonian fossils. Rocks of Coniacian and Santonian age are present high in the Chispa Summit, Ojinaga, and Boquillas Formations, and in the lower part of the Austin. The San Carlos, Aguja, Pen, and Austin Formations contain fossils of Campanian age. Fossils representing at least 38 Upper Cretaceous ammonite zones are present along the transect. Collections made in recent years in southwestern New Mexico and at Sierra de Cristo Rey just west of downtown El Paso, Texas, have been well treated and do not need revision. Taxonomic names and zonations published in the pre-1970 literature on the Rio Grande area of Texas have been updated. New fossil collections from the Big Bend National Park, Texas, allow for a much refined correlation

  11. Depositional environments of a coal-bearing section in the Upper Cretaceous Mesaverde Group, Routt County, Colorado

    USGS Publications Warehouse

    Gaffke, Thresa M.

    1979-01-01

    A 107-m (350 ft) section of coal-bearing rocks of the Upper Cretaceous Mesaverde Group that is exposed along an access road to the Edna Mine in Routt County, Colorado, records deposition of sediment during a regressive phase of the epicontinental sea. Each of the coal beds in the section occurs at the top of a bayfill sequence that records infilling of a bay sufficient to provide swamp conditions and allow formation of peat.

  12. Upper Campanian (Upper Cretaceous) cephalopods from the Parras Shale near Saucedas, Coahuila, Mexico

    NASA Astrophysics Data System (ADS)

    Ifrim, Christina; Stinnesbeck, Wolfgang; Espinosa, Belinda; Ventura, José Flores

    2015-12-01

    72 specimens of ammonites and the nautilid Eutrephoceras, collected from the upper Cretaceous Parras Shale at Saucedas in southern Coahuila, Mexico, are here assigned to twelve genera and fourteen species. The assemblage represents three to four upper Campanian biozones reaching from the Western Interior lower upper Campanian Exiteloceras jenneyi to the uppermost Campanian Tethyan Nostoceras hyatti biozone. Eutrephoceras irritilasi and Trachyscaphites sp. are endemic taxa, while Baculites taylorensis is restricted to the northern Gulf of Mexico Coast and E. jenneyi, Oxybeloceras crassum and Solenoceras elegans are Western Interior Seaway elements. Didymoceras donezianum is a southern Euramerican species, while Bostrychoceras polyplocum and N. hyatti occur throughout lower and middle latitudes. Diplomoceras cylindraceum and Phyllopachyceras forbesianum are cosmopolitan taxa with their main occurrences in the Maastrichtian; their record at Saucedas is the oldest of these species in North America. A clear paleobiogeographic signal is identified in the upper Campanian ammonite assemblages at Saucedas by a change from restricted towards geographically widespread faunas. This suggests gradual disappearence of faunal barriers which separated the Gulf Coast from the rest of the world.

  13. Vertebrate paleontological exploration of the Upper Cretaceous succession in the Dakhla and Kharga Oases, Western Desert, Egypt

    NASA Astrophysics Data System (ADS)

    Sallam, Hesham M.; O'Connor, Patrick M.; Kora, Mahmoud; Sertich, Joseph J. W.; Seiffert, Erik R.; Faris, Mahmoud; Ouda, Khaled; El-Dawoudi, Iman; Saber, Sara; El-Sayed, Sanaa

    2016-05-01

    The Campanian and Maastrichtian stages are very poorly documented time intervals in Africa's record of terrestrial vertebrate evolution. Upper Cretaceous deposits exposed in southern Egypt, near the Dakhla and Kharga Oases in the Western Desert, preserve abundant vertebrate fossils in nearshore marine environments, but have not yet been the focus of intensive collection and description. Our recent paleontological work in these areas has resulted in the discovery of numerous new vertebrate fossil-bearing localities within the middle Campanian Qusier Formation and the upper Campanian-lower Maastrichtian Duwi Formation. Fossil remains recovered from the Campanian-aged Quseir Formation include sharks, rays, actinopterygian and sarcopterygian fishes, turtles, and rare terrestrial archosaurians, including some of the only dinosaurs known from this interval on continental Africa. The upper Campanian/lower Maastrichtian Duwi Formation preserves sharks, sawfish, actinopterygians, and marine reptiles (mosasaurs and plesiosaurs). Notably absent from these collections are representatives of Mammalia and Avialae, both of which remain effectively undocumented in the Upper Cretaceous rocks of Africa and Arabia. New age constraints on the examined rock units is provided by 23 nannofossil taxa, some of which are reported from the Duwi Formation for the first time. Fossil discoveries from rock units of this age are essential for characterizing the degree of endemism that may have developed as the continent became increasingly tectonically isolated from the rest of Gondwana, not to mention for fully evaluating origin and diversification hypotheses of major modern groups of vertebrates (e.g., crown birds, placental mammals).

  14. Preliminary vitrinite and bitumen reflectance, total organic carbon, and pyrolysis data for samples from Upper and Lower Cretaceous strata, Maverick Basin, south Texas

    USGS Publications Warehouse

    Hackley, Paul C.; Dennen, Kristin O.; Gesserman, Rachel M.; Ridgley, Jennie L.

    2009-01-01

    The Lower Cretaceous Pearsall Formation, a regionally occurring limestone and shale interval of 500-600-ft maximum thickness (Rose, 1986), is being evaluated as part of an ongoing U.S. Geological Survey (USGS) assessment of undiscovered hydrocarbon resources in onshore Lower Cretaceous strata of the northern Gulf of Mexico. The purpose of this report is to release preliminary vitrinite and bitumen reflectance, total organic carbon, and pyrolysis data for Pearsall Formation, Glen Rose Formation, Hosston Formation, Austin Group, and Eagle Ford Group samples from the Maverick Basin in south Texas in order to aid in the characterization of these strata in this area. The preliminary nature of this report and the data contained herein reflect that the assessment and characterization of these samples is a work currently in progress. Pearsall Formation subdivisions are, in ascending stratigraphic order, the Pine Island Shale, James Limestone, and Bexar Shale Members (Loucks, 2002). The Lower Cretaceous Glen Rose Formation is also part of the USGS Lower Cretaceous assessment and produces oil in the Maverick Basin (Loucks and Kerans, 2003). The Hosston Formation was assessed by the USGS for undiscovered oil and gas resources in 2006 (Dyman and Condon, 2006), but not in south Texas. The Upper Cretaceous Austin Group is being assessed as part of the USGS assessment of undiscovered hydrocarbon resources in the Upper Cretaceous strata of the northern Gulf of Mexico and, along with the Upper Cretaceous Eagle Ford Group, is considered to be an important source rock in the Smackover-Austin-Eagleford Total Petroleum System (Condon and Dyman, 2006). Both the Austin Group and the Eagle Ford Group are present in the Maverick Basin in south Texas (Rose, 1986).

  15. Geology of the upper cretaceous and tertiary-coal-bearing rocks in the western part of the Wind River basin, Wyoming

    SciTech Connect

    Hickling, N.L.; Warlow, R.C.; Windolph, J.F.

    1989-01-01

    This book discusses coal-bearing rocks of the Frontier Formation which record the earliest peat accumulations in swamps overlying linear shoreline and delta lobe sand bodies formed during marine regressive cycles. Similarly, Mesaverde Formation coals formed above sandstones related to distributary channels, barrier bars, and prograding delta systems. In contrast, thick coal in the Meeteetse Formation formed in a subsiding intermontane basin. Tonsteins in these Upper Cretaceous coals and in tuff beds of the lower Eocene Indian Meadows Formation record repeated volcanism during the Late Cretaceous and early Tertiary.

  16. The First Freshwater Mosasauroid (Upper Cretaceous, Hungary) and a New Clade of Basal Mosasauroids

    PubMed Central

    Makádi, László; Caldwell, Michael W.; Ősi, Attila

    2012-01-01

    Mosasauroids are conventionally conceived of as gigantic, obligatorily aquatic marine lizards (1000s of specimens from marine deposited rocks) with a cosmopolitan distribution in the Late Cretaceous (90–65 million years ago [mya]) oceans and seas of the world. Here we report on the fossilized remains of numerous individuals (small juveniles to large adults) of a new taxon, Pannoniasaurus inexpectatus gen. et sp. nov. from the Csehbánya Formation, Hungary (Santonian, Upper Cretaceous, 85.3–83.5 mya) that represent the first known mosasauroid that lived in freshwater environments. Previous to this find, only one specimen of a marine mosasauroid, cf. Plioplatecarpus sp., is known from non-marine rocks in Western Canada. Pannoniasaurus inexpectatus gen. et sp. nov. uniquely possesses a plesiomorphic pelvic anatomy, a non-mosasauroid but pontosaur-like tail osteology, possibly limbs like a terrestrial lizard, and a flattened, crocodile-like skull. Cladistic analysis reconstructs P. inexpectatus in a new clade of mosasauroids: (Pannoniasaurus (Tethysaurus (Yaguarasaurus, Russellosaurus))). P. inexpectatus is part of a mixed terrestrial and freshwater faunal assemblage that includes fishes, amphibians turtles, terrestrial lizards, crocodiles, pterosaurs, dinosaurs and birds. PMID:23284766

  17. The first freshwater mosasauroid (Upper Cretaceous, Hungary) and a new clade of basal mosasauroids.

    PubMed

    Makádi, László; Caldwell, Michael W; Ősi, Attila

    2012-01-01

    Mosasauroids are conventionally conceived of as gigantic, obligatorily aquatic marine lizards (1000s of specimens from marine deposited rocks) with a cosmopolitan distribution in the Late Cretaceous (90-65 million years ago [mya]) oceans and seas of the world. Here we report on the fossilized remains of numerous individuals (small juveniles to large adults) of a new taxon, Pannoniasaurus inexpectatus gen. et sp. nov. from the Csehbánya Formation, Hungary (Santonian, Upper Cretaceous, 85.3-83.5 mya) that represent the first known mosasauroid that lived in freshwater environments. Previous to this find, only one specimen of a marine mosasauroid, cf. Plioplatecarpus sp., is known from non-marine rocks in Western Canada. Pannoniasaurus inexpectatus gen. et sp. nov. uniquely possesses a plesiomorphic pelvic anatomy, a non-mosasauroid but pontosaur-like tail osteology, possibly limbs like a terrestrial lizard, and a flattened, crocodile-like skull. Cladistic analysis reconstructs P. inexpectatus in a new clade of mosasauroids: (Pannoniasaurus (Tethysaurus (Yaguarasaurus, Russellosaurus))). P. inexpectatus is part of a mixed terrestrial and freshwater faunal assemblage that includes fishes, amphibians turtles, terrestrial lizards, crocodiles, pterosaurs, dinosaurs and birds. PMID:23284766

  18. Upper Cretaceous (Coniacian-Campanian) lithostratigraphy on the Saharan platform, Dahar Plateau, southern Tunisia

    NASA Astrophysics Data System (ADS)

    Khila, Amna; Ouaja, Mohamed; Zargouni, Fouad

    2016-03-01

    Four measured sections along the northern escarpment of the Dahar Plateau in southern Tunisia provide details of Cretaceous (Coniacian-Campanian) stratigraphy in this region of North Africa. These sections reveal various units of limestone with cross-stratification, limestone with in situ rudists, mud-supported limestone (carbonate mudstone, wackestone), argillaceous limestone, and limestone with stromatolites. These units are arranged vertically into several sequences of finer-grained limestone (mud-supported limestone, argillaceous limestone) overlain by coarser-grained limestone (limestone with cross-stratification, rudists, and/or stromatolites). Each sequence is interpreted as a shallowing upwards progression on a carbonate platform. Furthermore, cross-strqtified carbonate and beds with in situ rudists are more common in the lower parts of the measured sections, whereas units with stromatolites, argillaceous limestone, and finer-grained limestone are more common in the upper parts of the measured sections. The overall transition from the coarser-grained (higher energy) strata to the overlying finer-grained (lower energy) argillaceous strata is interpreted as having been caused by a relative fall in sea level that brought argillaceous sediment into the area. It is possible that the arrival of argillaceous sediments and the relative fall in sea level may have caused the demise of the rudist reefs. The lower interval (in which cross-stratified carbonates and in situ rudists are more common) is assigned to the Berressef Formation, whereas the upper interval (in which stromatolites, argillaceous limestone, and other fine-grained strata are more common) is assigned to the Toual Formation. Previous work suggests that the Berressef Formation is of Coniacian? to Santonian age, whereas the Toual Formation is of Campanian age. A regional cross section correlates these Cretaceous units on the Dahar Plateau with (1) rudist-bearing strata that are mapped in north

  19. Upper Cretaceous and Lower Jurassic strata in shallow cores on the Chukchi Shelf, Arctic Alaska

    USGS Publications Warehouse

    Houseknecht, David W.; Craddock, William H.; Lease, Richard O.

    2016-02-12

    Shallow cores collected in the 1980s on the Chukchi Shelf of western Arctic Alaska sampled pre-Cenozoic strata whose presence, age, and character are poorly known across the region. Five cores from the Herald Arch foreland contain Cenomanian to Coniacian strata, as documented by biostratigraphy, geochronology, and thermochronology. Shallow seismic reflection data collected during the 1970s and 1980s show that these Upper Cretaceous strata are truncated near the seafloor by subtle angular unconformities, including the Paleogene mid-Brookian unconformity in one core and the Pliocene-Pleistocene unconformity in four cores. Sedimentary structures and lithofacies suggest that Upper Cretaceous strata were deposited in a low accommodation setting that ranged from low-lying coastal plain (nonmarine) to muddy, shallow-marine environments near shore. These observations, together with sparse evidence from the adjacent western North Slope, suggest that Upper Cretaceous strata likely were deposited across all of Arctic Alaska.A sixth core from the Herald Arch contains lower Toarcian marine strata, indicated by biostratigraphy, truncated by a Neogene or younger unconformity. These Lower Jurassic strata evidently were deposited south of the arch, buried structurally to high levels of thermal maturity during the Early Cretaceous, and uplifted on the Herald thrust-fault system during the mid to Late Cretaceous. These interpretations are based on regional stratigraphy and apatite fission-track data reported in a complementary report and are corroborated by the presence of recycled palynomorphs of Early Jurassic age and high thermal maturity found in Upper Cretaceous strata in two of the foreland cores. This dataset provides evidence that uplift and exhumation of the Herald thrust belt provided sediment to the foreland during the Late Cretaceous.

  20. Relation of the Cretaceous formations to the Rocky Mountains in Colorado and New Mexico

    USGS Publications Warehouse

    Lee, Willis T.

    1916-01-01

    Some time ago, while working on a problem that involved the question of the presence or absence of islands near the close of the Cretaceous period in the region now occupied by the southern part of the Rocky Mountains, I was forced to the conclusion that no land masses or islands of any considerable size persisted there throughout the Cretaceous period, for I found no sedimentary rocks that were clearly derived from such islands. This result led to a reexamination of available information to see what evidence the sedimentary rocks in other areas near the present mountains could furnish, and I found rather unexpected confirmation of my conclusion. In the course of this study it became evident t that there is apparent conflict of testimony between different classes of fossils and that the physical evidence, including lithology, structure, and sequence of beds, is at variance with some of the commonly accepted correlations. In this state of uncertainty I tried to apply physiographic principles to see if they would throw any light on the interrelations of the interrelations of the Cretaceous formations of the Rocky Mountain region and on the events that opened and closed the period. This led me to a conclusion similar to that reached by the paleontologist C. A. White many years ago, namely, that the Upper Cretaceous formations up to and including the Laramie extended across the site of the mountains.

  1. Provenance and U-Pb geochronology of the Upper Cretaceous El Chanate Group, northwest Sonora, Mexico, and its tectonic significance

    USGS Publications Warehouse

    Jacques-Ayala, C.; Barth, A.P.; Wooden, J.L.; Jacobson, C.E.

    2009-01-01

    The Upper Cretaceous El Chanate Group, northwest Sonora, Mexico, is a 2.8km thick clastic sedimentary sequence deposited in a continental basin closely related to volcanic activity. It consists of three formations: the Pozo Duro (oldest), the Anita, and the Escalante (youngest). Petrographic study, conglomerate pebble counts, and U-Pb geochronology of detrital zircons were performed to determine the source and age of this sequence, and to interpret its tectonic setting. In the sandstones of all three formations, the most abundant grains are those of volcanic composition (Q38F22L 40, Q35F19L46, and Q 31F22L47, respectively). The Pozo Duro Formation includes well-rounded quartz-arenite clast conglomerates, whereas conglomerates of the two upper units have clasts predominantly of andesitic and rhyolitic composition. The most likely source for these sediments was the Jurassic volcanic arc exposed in northern Sonora and southern Arizona. Zircons from five sandstone samples define two main age groups, Proterozoic and Mesozoic. The first ranges mostly from 1000 to 1800Ma, which suggests the influence of a cratonic source. This zircon suite is interpreted to be recycled and derived from the same source area as the quartz-rich sandstone clasts in the basal part of the section. Mesozoic zircons range from Triassic to Late Cretaceous, which confirms the proposed Late Cretaceous age for the sequence, and also corroborates Jurassic felsic source rocks. Another possible source was the Alisitos volcanic arc, exposed along the western margin of the Baja California Peninsula. Of regional significance is the great similarity between the El Chanate Group and the McCoy Mountains Formation of southeastern California and southwestern Arizona. Both are Cretaceous, were deposited in continental environments, and have similar zircon-age patterns. Also, both exhibit intense deformation and locally display penetrative foliation. These features strongly suggest that both units underwent

  2. The Lower Cretaceous Chinkeh Formation: A frontier-type play in the Liard basin of western Canada

    SciTech Connect

    Leckie, D.A. ); Potocki, D.J. ); Visser, K. )

    1991-08-01

    The Lower Cretaceous Liard basin in western Canada covers an area of 9,500 km{sup 2} (3,668 mi{sup 2}) but is relatively unexplored despite its size. The present-day expression of the basin, which formed during the latest Cretaceous to early Tertiary, trends north-south and is delineated by the outcrop of the coarse-clastic Upper Cretaceous Dunvegan Formation. The lowermost Cretaceous unit, herein named the Chinkeh Formation, is up to 32 m (105 ft) thick and unconformably overlies older Paleozoic strata. The Chinkeh Formation contains four major lithotypes: (1) conglomeratic breccia interpreted as debris-flow or talus deposits, (2) interbedded coal, carbonaceous as nonmarine valley fill or channel deposits, (3) conglomeratic lag related to marine deposits, (3) conglomeratic lag related to marine transgression, and (4) upward-coarsening sandstone interpreted as abandoned shoreline deposits. Cretaceous strata in the Liard basin have gave petroleum source-rock and reservoir potential, and hydrocarbons may be present in sandstone of the Chinkeh Formation. Potential play types include stratigraphic traps formed by incised-valley deposits and shallow-marine sandstone pinching out laterally into marine shales of the Garbutt Formation. A potential structural play may occur along the Bovie fault zone where reservoirs may abut against a shale seal on the eastern side of the fault. Potential source rocks include the lowermost Garbutt Formation and underlying Triassic Toad Garbutt formations. The Chinkeh Formation sandstone has porosity values of 8-18%.

  3. Biostratigraphy and paleoenvironments of the Stöckelwaldgraben section (Northern Calcareous Alps, Upper Cretaceous)

    NASA Astrophysics Data System (ADS)

    Bukenberger, Patrick; Wolfgring, Erik; Wagreich, Michael

    2016-04-01

    The Stöckelwaldgraben section exposes grey marls of the Streiteck- and Grabenbach formations, Gosau-Group, Upper Cretaceous, located in Austria. Frequent tempestite events were recorded throughout the section. The Stöckelwandgraben section represents a shelf environment from the southern margin of the Penninic Ocean. Biostratigraphic data indicates the Dicarinella concavata to Dicarinella asymetrica Zone for planktic foraminifera, which covers late Coniacian to early Santonian in age. The Coniacian/Santonian boundery was marked by the first occurrence of Sigalia carpatica and the first occurrence of Dicarinella asymetrica. The primary marker, defined by the GSSP (Global Stratotype Section and Point), Platyceramus undulatoplicatus, could not be found due to bad preservation of macrofossils. A gradual sea-level rise from a shallow marine to a neritic environment was observed by changes in the planktic/benthic foraminifera ratio, the faunal compositions and the diversity of benthic foraminifera. Only few planktonic foraminifera but abundant large miliolids were found in the Coniacian samples which suggests very shallow conditions. The content of planktonic foraminifera was gradually increasing up to 40% in the Santonian, where the planktic foraminiferal fauna was consisting mostly of large sized marginotruncanids, biserial planktics, dicarinellids and archeoglobigerinids. The assumed waterdepth ranges from approximately 20 meters to a maximum of 150 meters and is based on foraminiferal paleoecology. The state of preservation of the benthic foraminifera can be considered moderate to well while planktonic foraminifera were generally found to be well preserved High-magnesium calcite tests of miliolids such as Quinqueloculina sp. and Spiroloculina sp. were decalcified and in some cases only infillings of pyrite could be observed. Observing palaeoenvironmental changes in foraminiferal communities combined with an established chronostratigraphic framework will lead to a

  4. Scaphitid ammonites from the Upper Cretaceous of KwaZulu-Natal and Eastern Cape Province, South Africa

    NASA Astrophysics Data System (ADS)

    Kennedy, William James; Klinger, Herbert Christian

    2013-12-01

    Kennedy, W.J. and Klinger, H.C. 2013. Scaphitid ammonites from the Upper Cretaceous of KwaZulu-Natal and Eastern Cape Province, South Africa. Acta Geologica Polonica, 63 (4), 527-543. Warszawa. Scaphitid ammonites are described and illustrated from the Upper Cretaceous of the coastal region of north-eastern South Africa. Scaphites kieslingswaldensis Langenhan and Grundey, 1891, Scaphites manasoaensis Collignon, 1965, and Yezoites concinna sp. nov. occur in the Coniacian part of the St Lucia Formation in northern KwaZulu-Natal. A further Yezoites sp. may also be from this level. Argentoscaphites corrugatus sp. nov. occurs in the Santonian to Lower Campanian Mzamba Formation on the northernmost coast of Eastern Cape Province. Yezoites australis sp. nov. occurs in the Upper Santonian part of the St Lucia and Mzamba formations of these areas, and Scaphites reesidei Collignon, 1969, is recorded from the Lower Campanian part of the Mzamba Formation. The scaphitid assemblage includes species previously described from Western Europe and Madagascar, together with Argentoscaphites, previously known only from Patagonia (and possibly South India). Dimorphism is recognised in Scaphites reesidei, Yezoites concinna sp. nov. and Y. australis sp. nov. Argentoscaphites corrugatus sp. nov. and Yezoites sp. are represented by microconchs only. Dimorphism has not been recognised in Scaphites kieslingswaldensis.

  5. Definition of Greater Gulf Basin Lower Cretaceous and Upper Cretaceous Lower Cenomanian Shale Gas Assessment Unit, United States Gulf of Mexico Basin Onshore and State Waters

    USGS Publications Warehouse

    Dennen, Kristin O.; Hackley, Paul C.

    2012-01-01

    An assessment unit (AU) for undiscovered continuous “shale” gas in Lower Cretaceous (Aptian and Albian) and basal Upper Cretaceous (lower Cenomanian) rocks in the USA onshore Gulf of Mexico coastal plain recently was defined by the U.S. Geological Survey (USGS). The AU is part of the Upper Jurassic-Cretaceous-Tertiary Composite Total Petroleum System (TPS) of the Gulf of Mexico Basin. Definition of the AU was conducted as part of the 2010 USGS assessment of undiscovered hydrocarbon resources in Gulf Coast Mesozoic stratigraphic intervals. The purpose of defining the Greater Gulf Basin Lower Cretaceous Shale Gas AU was to propose a hypothetical AU in the Cretaceous part of the Gulf Coast TPS in which there might be continuous “shale” gas, but the AU was not quantitatively assessed by the USGS in 2010.

  6. Dinosaur ichnofauna of the Upper Jurassic/Lower Cretaceous of the Paraná Basin (Brazil and Uruguay)

    NASA Astrophysics Data System (ADS)

    Francischini, H.; Dentzien–Dias, P. C.; Fernandes, M. A.; Schultz, C. L.

    2015-11-01

    Upper Jurassic and Lower Cretaceous sedimentary layers are represented in the Brazilian Paraná Basin by the fluvio-aeolian Guará Formation and the Botucatu Formation palaeoerg, respectively, overlapped by the volcanic Serra Geral Formation. In Uruguay, the corresponding sedimentary units are named Batoví and Rivera Members (both from the Tacuarembó Formation), and the lava flows constitute the Arapey Formation (also in Paraná Basin). Despite the lack of body fossils in the mentioned Brazilian formations, Guará/Batoví dinosaur fauna is composed of theropod, ornithopod and wide-gauge sauropod tracks and isolated footprints, as well as theropod teeth. In turn, the Botucatu/Rivera dinosaur fauna is represented by theropod and ornithopod ichnofossils smaller than those from the underlying units. The analysis of these dinosaur ichnological records and comparisons with other global Mesozoic ichnofauna indicates that there is a size reduction in dinosaur fauna in the more arid Botucatu/Rivera environment, which is dominated by aeolian dunes. The absence of sauropod trackways in the Botucatu Sandstone fits with the increasingly arid conditions because it is difficult for heavy animals to walk on sandy dunes, as well as to obtain the required amount of food resources. This comparison between the Upper Jurassic and Lower Cretaceous dinosaur fauna in south Brazil and Uruguay demonstrates the influence of aridization on the size of animals occupying each habitat.

  7. Depositional environment and diagenesis of Teapot Sandstone (Upper Cretaceous), Converse and Natrona counties, Wyoming

    SciTech Connect

    Coughlan, P.

    1983-08-01

    The Teapot Sandstone forms the upper member of the Upper Cretaceous Mesa Verde Formation in the Powder River basin. Previous interpretations of the Teapot based on outcrop or subsurface data range from nearshore marine to fluvial. Marine lithofacies coarsen upward from bioturbated offshore siltstone to nearshore sandstone with large, pellet-lined ophiomorpha and overlying well-sorted, horizontally laminated foreshore sandstone exhibiting ridge and runnel topography. Marine foreshore sandstone is overlain by complexly interbedded sandstone and carbonaceous shale in stacked fining-upward sequences of the delta plain. Fining-upward units are interpreted as abandoned channels, whereas coarsening-upward sequences are interpreted as interdistributary bay or lagoonal deposits. Capping the sequence is a thick, cross-bedded fluvial section consisting of levee, point bar, and channel sand deposits. The Teapot Sandstone has a complex diagenetic history. Siderite and framboidal pyrite formed early in the diagenetic sequence at shallow depths of burial under anaerobic conditions. Pore-filling kaolinite, chlorite, and quartz overgrowths formed coevally following dissolution of relatively unstable framework grains. Poikilotopic calcite cement is locally abundant and extensively replaces framework grains. Nearshore marine and fluvial sandstone are potentially hydrocarbon reservoirs, although authigenic clays have significantly reduced permeability. Reservoir potential of well-sorted foreshore marine sandstone was destroyed by pore-filling calcite cement. However, tightly cemented sandstone forms a potential diagenetic trapping mechanism.

  8. Paleoshorelines in the Upper Cretaceous Point Lookout Sandstone, southern San Juan Basin, New Mexico

    USGS Publications Warehouse

    Zech, R.S.

    1982-01-01

    LANDSAT images and aerial photography reveal several parallel linear features as much as 17 km long and 0.7 km wide. Detailed cross sections normal to a linear feature show it to be an exhumed paleoshoreline containing several overlapping sandstone units. Each unit tends to pinchout into the shales of the overlying Menefee Formation, showing a range of depositional environments including upper shoreface, foreshore, washover and eolian. Paleogeomorphic elements, predominately beach ridges and interridge swales, shape the upper surface of the sandstone and produce a relief as great as 4.2 m. The various components found in the paleoshoreline create a trellis-like drainage pattern that contrasts with the regional dendritic drainage pattern; the resulting linear feature is easily discernible on aerial photography and LANDSAT images. The rapid lithologic and thickness changes of the sandstone bodies in these linear features provide excellent potential as stratigraphic trap for hydrocarbons. Paleoshoreline facies are likely to be preserved in areas of thickest marginal marine regressive sand accumulation and similar paleoshoreline systems may be preserved at depth in the Point Lookout (Sandstone) or other Cretaceous sandstones.

  9. Evolution and palaeoenvironment of the Bauru Basin (Upper Cretaceous, Brazil)

    NASA Astrophysics Data System (ADS)

    Fernandes, Luiz Alberto; Magalhães Ribeiro, Claudia Maria

    2015-08-01

    The Bauru Basin was one of the great Cretaceous desert basins of the world, evolved in arid zone called Southern Hot Arid Belt. Its paleobiological record consists mainly of dinosaurs, crocodiles and turtles. The Bauru Basin is an extensive region of the South American continent that includes parts of the southeast and south of Brazil, covering an area of 370,000 km2. It is an interior continental basin that developed as a result of subsidence of the central-southern part of the South-American Platform during the Late Cretaceous (Coniacian-Maastrichtian). This sag basin is filled by a sandy siliciclastic sequence with a preserved maximum thickness of 480 m, deposited in semiarid to desert conditions. Its basement consists of volcanic rocks (mainly basalts) of the Lower Cretaceous (Hauterivian) Serra Geral basalt flows, of the Paraná-Etendeka Continental Flood Basalt Province. The sag basin was filled by an essentially siliciclastic psammitic sequence. In lithostratigraphic terms the sequence consists of the Caiuá and Bauru groups. The northern and northeastern edges of the basin provide a record of more proximal original deposits, such as associations of conglomeratic sand facies from alluvial fans, lakes, and intertwined distributary river systems. The progressive basin filling led to the burial of the basaltic substrate by extensive blanket sand sheets, associated with deposits of small dunes and small shallow lakes that retained mud (such as loess). Also in this intermediate context between the edges (more humid) and the interior (dry), wide sand sheet areas crossed by unconfined desert rivers (wadis) occurred. In the central axis of the elliptical basin a regional drainage system formed, flowing from northeast to southwest between the edges of the basin and the hot and dry inner periphery of the Caiuá desert (southwest). Life in the Bauru Basin flourished most in the areas with the greatest water availability, in which dinosaurs, crocodiles, turtles, fish

  10. Current oil and gas production from North American Upper Cretaceous chalks

    USGS Publications Warehouse

    Scholle, Peter A.

    1977-01-01

    Production of oil and natural gas from North American chalks has increased significantly during the past five years, spurred by the prolific production from North Sea chalks, as well as by higher prices and improved production technology. Chalk reservoirs have been discovered in the Gulf Coast in the Austin Group, Saratoga and Annona Chalks, Ozan Formation, Selma Group, Monroe gas rock (an informal unit of Navarro age), and other Upper Cretaceous units. In the Western Interior, production has been obtained from the Cretaceous Niobrara and Greenhorn Formations. Significant, though subcommercial, discoveries of natural gas and gas condensate also have been made in the Upper Cretaceous Wyandot Formation on the Scotian Shelf of eastern Canada. All North American chalk units share a similar depositional and diagenetic history. The chalks consist primarily of whole and fragmented coccoliths with subordinate planktonic and benthonic Foraminifera, inoceramid prisms, oysters, and other skeletal grains. Most have between 10 and 35 percent HCl-insoluble residue, predominantly clay. Deposition was principally below wave base in tens to hundreds of meters of water. The diagenetic history of a chalk is critical in determining its reservoir potential. All chalk has a stable composition (low-Mg calcite) and very high primary porosity. With subsequent burial, mechanical and chemical (solution-transfer) compaction can reduce or completely eliminate pore space. The degree of loss of primary porosity in chalk sections is normally a direct function of the maximum depth to which it has been buried. Pore-water chemistry, pore-fluid pressures, and tectonic stresses also influence rates of cementation. Oil or gas reservoirs of North American chalk fall into three main groups: 1. Areas with thin overburden and significant primary porosity retention (for example, Niobrara Formation of Kansas and eastern Colorado). 2. Areas with thicker overburden but considerable fracturing. Here primary

  11. Stratigraphy and depositional environments of Fox Hills Formation (Late Cretaceous), Williston basin

    SciTech Connect

    Daly, D.J.

    1986-08-01

    The Fox Hills Formation (Late Cretaceous, Maestrichtian) was investigated where it crops out along the southern flank of the Williston basin and in the subsurface over the central portion of the basin, using 300 well logs. The formation is conformable and gradational with the underlying Pierre formation and can be either conformable or unconformable with the overlying Hell Creek Formation. The Fox Hills Formation is younger, thicker, and stratigraphically more complex to the east and is comprised of marginal marine sediments deposited during the final Cretaceous regression. To the west, the Fox Hills Formation is an upward-coarsening unit generally 30 to 45 m thick and usually contains three members: from the base, Trail City, Timber Lake, and Colgate. The lower Fox Hills (Trail City, Timber Lake) is generally dominated by hummocky bedding and contains a variety of trace fossils, most notably Ophiomorpha. The upper Fox Hills (Colgate), where present, is characterized by cross-bedding. To the east, including the type area, the section is generally 80 to 100 m thick and contains four members: from the base, Trail City, Timber Lake, Iron Lightning (Colgate and Bullhead lithofacies), and Linton. In contrast to the section in the west, this section is as much as three times thicker, contains abundant body fossils, generally lacks hummocky bedding, and contains the Bullhead and Linton strata. In the west, the strata represent lower shoreface deposits, predominantly of storm origin (lower Fox Hills), overlain by upper shoreface and fluvial deposits (upper Fox Hills). In the east, the lower Fox Hills contains deposits of the lower shoreface (Trail City) and a barrier bar complex (Timber Lake), overlain by the deltaic deposits of the upper Fox Hills (Iron Lightning, Linton).

  12. A pterodactyloid pterosaur from the Upper Cretaceous Lapurr sandstone, West Turkana, Kenya.

    PubMed

    O'Connor, Patrick M; Sertich, Joseph J W; Manthi, Fredrick K

    2011-03-01

    An isolated pterosaurian caudal cervical (~ postcervical) vertebra was recovered from the Upper Cretaceous Lapurr sandstone of West Turkana, northwestern Kenya. The vertebral centrum is short, wide, and dorsoventrally compressed. Although the specimen is lightly built similar to most pterosaurs, it is here referred to Pterodactyloidea and tentatively to the Azhdarchidae in that it lacks pneumatic features on both the centrum and neural arch. This represents one of the few pterosaurs recovered from the entirety of Afro-Arabia, the first pterosaur recovered from the Cretaceous of East Africa, and, significantly, a specimen that was recovered from fluvial deposits rather than the near-shore marine setting typical of most pterosaur discoveries.

  13. Maps showing thermal maturity of Upper Cretaceous marine shales in the Wind River Basin, Wyoming

    USGS Publications Warehouse

    Finn, Thomas M.; Pawlewicz, Mark J.

    2013-01-01

    The Wind River Basin is a large Laramide (Late Cretaceous through Eocene) structural and sedimentary basin that encompasses about 7,400 square miles in central Wyoming. The basin is bounded by the Washakie Range, Owl Creek, and southern Bighorn Mountains on the north, the Casper arch on the east and northeast, the Granite Mountains on the south, and the Wind River Range on the west. Important conventional and unconventional oil and gas resources have been discovered and produced from reservoirs ranging in age from Mississippian through Tertiary. It has been suggested that various Upper Cretaceous marine shales are the principal hydrocarbon source rocks for many of these accumulations. Numerous source rock studies of various Upper Cretaceous marine shales throughout the Rocky Mountain region have led to the conclusion that these rocks have generated, or are capable of generating, oil and (or) gas. With recent advances and success in horizontal drilling and multistage fracture stimulation there has been an increase in exploration and completion of wells in these marine shales in other Rocky Mountain Laramide basins that were traditionally thought of only as hydrocarbon source rocks. Important parameters that control hydrocarbon production from shales include: reservoir thickness, amount and type of organic matter, and thermal maturity. The purpose of this report is to present maps and a structural cross section showing levels of thermal maturity, based on vitrinite reflectance (Ro), for Upper Cretaceous marine shales in the Wind River Basin.

  14. Correlation of Upper Cretaceous strata from Lima Peaks area to Madison Range, southwestern Montana and southeastern Idaho, USA

    USGS Publications Warehouse

    Dyman, T.S.; Tysdal, R.G.; Perry, W.J.; Obradovich, J.D.; Haley, J.C.; Nichols, D.J.

    1997-01-01

    An 40Ar/39Ar age of 85.81 Ma ?? 0.22 my was obtained on sanidine from a volcanic procellanite bed near the top of the 2135 + m-thick Upper Cretaceous Frontier Formation in the Lima Peaks area of southwestern Montana. This early Santonian age, combined with previously determined age data including a palynological age of Cenomanian for the lower Frontier at Lima Peaks, and a U-Pb isotopic date of about 95 Ma for the base of the Frontier Formation in the eastern Pioneer Mountains north of the Lima Peaks area, provides an age range for this nonmarine formation. In the Madison Range, farther east in southwestern Montana, this age range corresponds to marine strata of not only the Frontier Formation, but also the overlying Cody Shale and Telegraph Creek Formation, a sequence that totals less than 760 m thick. The Upper Cretaceous marine formations of the Madison Range are closely zoned by molluscan faunas that are well constrained with radiometric dates. The 40Ar/39Ar age of 85.81 Ma ?? 0.22 my at Lima Peaks is bracketed by radiometric dates for the Scaphites depressus - Protexanites bourgeoisianus biozone and the overlying Clioscaphites saxitonianus - Inoceramus undulatoplicatus biozone of the Western Interior. Fossils of both of these biozones are present in the Cody Shale and the Telegraph Creek Formation in the Madison Range. The Telegraph Creek contains two units of volcanic ash that are approximate time equivalents of the volcanic procellanite of the Lima Peaks area. Clasts in the conglomerate of the upper part of the Frontier in the Lima Peaks area were shed during the initial stages of uplift of the Blacktail-Snowcrest highlands which rose to the north. The dated porcellanite lies above the conglomerates and indicates that the uplift was initiated by middle or late Coniacian, 87-88 Ma. ?? 1997 Academic Press Limited.

  15. Stratigraphic framework and regional subsurface geology of upper Cretaceous through lower Eocene rocks in Wind River basin, Wyoming

    SciTech Connect

    Hogle, D.G.; Jones, R.W.

    1989-03-01

    A detailed stratigraphic study of over 6000 m of Upper Cretaceous through lower Eocene sedimentary rocks in the Wind River basin. Wyoming, has refined and expanded previous work and conclusions. A much larger data base than previously available was assembled to include a correlation net of 325 geophysical well logs, 36 drill holes with palynological age dates, lithology logs of drill hoes, and limited surface exposures. The most significant results and conclusions from this study are summarized below. (1) The lower part of the Mesaverde Formation intertongues with marine sandstones and shales of the upper Cody Shale to the east and with marine sandstones of the lower Mesaverde Formation in the Big Horn basin to the north. (2) An unconformity between the Mesaverde and Fort Union Formations in the southwestern part of the basin can be traced into the subsurface. (3) During the latest Cretaceous and Paleocene, over 2100 m of Lance Formation and over 2700 m of Fort Union Formation were deposited in the northeastern part of the basin. Ponding during the Paleocene is demonstrated by correlation and subsurface mapping of over 900 m of shale and siltstone in the Waltman Shale Member of the Fort Union Formation. (4) The Lance and Fort Union Formations can be mapped in the subsurface throughout much of the basin. The Lance Formation pinches out in the western part of the basin. (5) Coal beds can be traced for short distances in the subsurface; coal bed occurrence is documented for the Mesaverde, lower Fort Union, and Meeteetse Formations in the southwestern, northern and central, and northwestern parts of the basin, respectively.

  16. Maps showing thermal maturity of Upper Cretaceous marine shales in the Bighorn Basin, Wyoming and Montana

    USGS Publications Warehouse

    Finn, Thomas M.; Pawlewicz, Mark J.

    2014-01-01

    The Bighorn Basin is one of many structural and sedimentary basins that formed in the Rocky Mountain foreland during the Laramide orogeny, a period of crustal instability and compressional tectonics that began in latest Cretaceous time and ended in the Eocene. The basin is nearly 180 mi long, 100 mi wide, and encompasses about 10,400 mi2 in north-central Wyoming and south-central Montana. The basin is bounded on the northeast by the Pryor Mountains, on the east by the Bighorn Mountains, and on the south by the Owl Creek Mountains). The north boundary includes a zone of faulting and folding referred to as the Nye-Bowler lineament. The northwest and west margins are formed by the Beartooth Mountains and Absaroka Range, respectively. Important conventional oil and gas resources have been discovered and produced from reservoirs ranging in age from Cambrian through Tertiary. In addition, a potential unconventional basin-centered gas accumulation may be present in Cretaceous reservoirs in the deeper parts of the basin. It has been suggested by numerous authors that various Cretaceous marine shales are the principal source rock for these accumulations. Numerous studies of various Upper Cretaceous marine shales in the Rocky Mountain region have led to the general conclusion that these rocks have generated or are capable of generating oil and (or) gas. In recent years, advances in horizontal drilling and multistage fracture stimulation have resulted in increased exploration and completion of wells in Cretaceous marine shales in other Rocky Mountain Laramide basins that were previously thought of only as hydrocarbon source rocks. Important parameters controlling hydrocarbon production from these shale reservoirs include: reservoir thickness, amount and type of organic matter, and thermal maturity. The purpose of this report is to present maps and a cross section showing levels of thermal maturity, based on vitrinite reflectance (Ro), for selected Upper Cretaceous marine

  17. Fossil woods from the Late Cretaceous Aachen Formation.

    PubMed

    Meijer

    2000-11-01

    Silicified fossil woods from the Late Cretaceous (Santonian) Aachen Formation of northeast Belgium, southernmost Netherlands and adjacent Germany were investigated. Gymnosperms dominate this assemblage: Taxodioxylon gypsaceum, T. cf. gypsaceum, T. cf. albertense (all Taxodiaceae), Dammaroxylon aachenense sp. nov. (Araucariaceae), Pinuxylon sp. (Pinaceae), and Scalaroxylon sp. (Cycad or Cycadeoid). Angiosperms are minor constituents: Nyssoxylon sp. (Nyssaceae?, Cornaceae?), Mastixioxylon symplocoides sp. nov. (Mastixiaceae?, Symplocaceae?), Plataninium decipiens (Platanaceae) and Paraphyllanthoxylon cf. marylandense (Anacardiaceae?, Burseraceae?, Lauraceae?).The composition of this assemblage and the anatomy of the woods indicate a seasonal and humid warm-temperate to subtropical climate.

  18. Stratigraphic correlation of the Late Cretaceous Simsima Formation United Arab Emirates and Akveren Formation, northwest Turkey

    NASA Astrophysics Data System (ADS)

    Abdelghany, O.; Abu Saima, M.; Ramazanoglu, S.; Arman, H.

    2015-11-01

    Latest Cretaceous (Campanian-Maastrichtian) microfossils are used to correlate the carbonate rocks of the Simsima Formation in the northeastern part of the Arabian Peninsula (Northern Oman Mountains, United Arab Emirates and Oman) with the Akveren Formation in Kandira (northwest Turkey, near Black Sea region). Both formations have characteristically rich planktonic foraminiferal and calcareous nannofossil faunal assemblages that permit the recognition of the Globotruncanella havanensis Zone and Quadrum sissinghii Zone CC22. The palaeontological data is used to build an appropriate palaeoenvironmental model for the latest Cretaceous Aruma Group in the Oman Mountains foreland basin. The study reveals that the Late Cretaceous formations of UAE and Turkey can be divided into an open marine carbonate shelf facies (planktonic foraminifera/calcareous nannofossil biomicrite) and a shallow-marine carbonate facies (rudistids, coralline algal foraminiferal biomicrite).

  19. Geochemistry of the Jurassic and Upper Cretaceous shales from the Molango Region, Hidalgo, eastern Mexico: Implications for source-area weathering, provenance, and tectonic setting

    NASA Astrophysics Data System (ADS)

    Armstrong-Altrin, John S.; Nagarajan, Ramasamy; Madhavaraju, Jayagopal; Rosalez-Hoz, Leticia; Lee, Yong Il; Balaram, Vysetti; Cruz-Martínez, Adriana; Avila-Ramírez, Gladis

    2013-04-01

    This study focuses on the Jurassic (Huayacocotla and Pimienta Formations) and Upper Cretaceous (Méndez Formation) shales from the Molango Region, Hidalgo, Mexico. In this article, we discuss the mineralogy, major, and trace element geochemistry of the Mesozoic shales of Mexico. The goal of this study is to constrain the provenance of the shales, which belong to two different periods of the Mesozoic Era and to understand the weathering conditions and tectonic environments of the source region.

  20. Predictive Upper Cretaceous to Early Miocene Paleogeography of the San Andreas Fault System

    NASA Astrophysics Data System (ADS)

    Burnham, K.

    2006-12-01

    Paleogeographic reconstruction of the region of the San Andreas fault was hampered for more than twenty years by the apparent incompatibility of authoritative lithologic correlations. These led to disparate estimates of dextral strike-slip offsets, notably 315 km between Pinnacles and Neenach Volcanics (Matthews, 1976), versus 563 km between Anchor Bay and Eagle Rest Peak (Ross et al., 1973). In addition, estimates of total dextral slip on the San Gregorio fault have ranged from 5 km to 185 km. Sixteen upper Cretaceous and Paleogene conglomerates of the California Coast Ranges, from Anchor Bay to Simi Valley, have been included in a multidisciplinary study. Detailed analysis, including microscopic petrography and microprobe geochemistry, verified Seiders and Cox's (1992) and Wentworth's (1996) correlation of the upper Cretaceous Strata of Anchor Bay with an unnamed conglomerate east of Half Moon Bay. Similar detailed study, with the addition of SHRIMP U/Pb zircon dating, verified that the Paleocene or Eocene Point Reyes Conglomerate at Point Reyes is a tectonically displaced segment of the Carmelo Formation of Point Lobos. These studies centered on identification of matching unique clast varieties, rather than on simply counting general clast types, and included analyses of matrices, fossils, paleocurrents, diagenesis, adjacent rocks, and stratigraphy. The work also led to three new correlations: the Point Reyes Conglomerate with granitic source rock at Point Lobos; a magnetic anomaly at Black Point with a magnetic anomaly near San Gregorio; and the Strata of Anchor Bay with previously established source rock, the potassium-poor Logan Gabbro (Ross et al., 1973) at a more recently recognized location (Brabb and Hanna, 1981; McLaughlin et al., 1996) just east of the San Gregorio fault, south of San Gregorio. From these correlations, an upper Cretaceous early Oligocene paleogeography of the San Andreas fault system was constructed that honors both the Anchor Bay

  1. First North American occurrence of Anacoracid selachian Squalicorax yangaensis, Upper Cretaceous Dalton sandstone, near Crownpoint, New Mexico

    SciTech Connect

    Wolberg, D.L.; Bellis, D. )

    1989-09-01

    This report documents the first North American occurrence of Squalicorax yangaensis in the Upper Cretaceous Dalton sandstone, Borrego Pass area, southeast of Crownpoint, New Mexico. The Dalton sandstone has been interpreted to be a regressive coastal barrier sandstone deposited parallel to the southeast-trending shoreline of the Late Cretaceous epeiric seaway.

  2. Polymorphism in the Upper Cretaceous ammonite Libycoceras Ismaeli (Zittel)

    NASA Astrophysics Data System (ADS)

    Kassab, A. S.; Hamama, H. H.

    This work gives a full account of the ontogenetic development and variation in a population of the Upper Cretaneous sphenodiscid ammonite Libycoceras ismaeli hadens subsp. nov. The collection, from a single narrow stratum and the same locality, displays a kind of polymorphism. Such polymorphism is reflected strikingly as differences in shell shape and ornament. Some results of the ontogenetic and statistical analyses indicate sexual dimorphism, whereas others may show ecophenotypic polymorphism. The polymorphic variants are identical in their early ontogeny, but differ in mature and adult stages.

  3. Upper Cretaceous sequences and sea-level history, New Jersey Coastal Plain

    USGS Publications Warehouse

    Miller, K.G.; Sugarman, P.J.; Browning, J.V.; Kominz, M.A.; Olsson, R.K.; Feigenson, M.D.; Hernandez, J.C.

    2004-01-01

    We developed a Late Cretaceous sealevel estimate from Upper Cretaceous sequences at Bass River and Ancora, New Jersey (ODP [Ocean Drilling Program] Leg 174AX). We dated 11-14 sequences by integrating Sr isotope and biostratigraphy (age resolution ??0.5 m.y.) and then estimated paleoenvironmental changes within the sequences from lithofacies and biofacies analyses. Sequences generally shallow upsection from middle-neritic to inner-neritic paleodepths, as shown by the transition from thin basal glauconite shelf sands (transgressive systems tracts [TST]), to medial-prodelta silty clays (highstand systems tracts [HST]), and finally to upper-delta-front quartz sands (HST). Sea-level estimates obtained by backstripping (accounting for paleodepth variations, sediment loading, compaction, and basin subsidence) indicate that large (>25 m) and rapid (???1 m.y.) sea-level variations occurred during the Late Cretaceous greenhouse world. The fact that the timing of Upper Cretaceous sequence boundaries in New Jersey is similar to the sea-level lowering records of Exxon Production Research Company (EPR), northwest European sections, and Russian platform outcrops points to a global cause. Because backstripping, seismicity, seismic stratigraphic data, and sediment-distribution patterns all indicate minimal tectonic effects on the New Jersey Coastal Plain, we interpret that we have isolated a eustatic signature. The only known mechanism that can explain such global changes-glacio-eustasy-is consistent with foraminiferal ??18O data. Either continental ice sheets paced sea-level changes during the Late Cretaceous, or our understanding of causal mechanisms for global sea-level change is fundamentally flawed. Comparison of our eustatic history with published ice-sheet models and Milankovitch predictions suggests that small (5-10 ?? 106 km3), ephemeral, and areally restricted Antarctic ice sheets paced the Late Cretaceous global sea-level change. New Jersey and Russian eustatic estimates

  4. Porosphaera globularis (Phillips, 1829) (Porifera, Calcarea) in the Campanian (Upper Cretaceous) of extra-Carpathian Poland

    NASA Astrophysics Data System (ADS)

    Jurkowska, Agata; Świerczewska-Gładysz, Ewa; Dubicka, Zofia; Olszewska-Nejbert, Danuta

    2015-03-01

    The stratigraphical distribution of Porosphaera globularis, a common calcareous sponge in the Upper Cretaceous (mostly Campanian and Maastrichtian) of Poland was studied. The presented material, both new and from museum collections, comes from the Campanian of the Miechow Synclinorium, in southern Poland, and from the Lower Campanian of Mielnik in the south-eastern part of the Mazury-Podlasie Homocline, in eastern Poland. The significance of the species in extra-regional correlation, its palaeobiogeography and stratigraphical potential is critically reviewed.

  5. Example of inner-shelf sand ridges from Upper Cretaceous Eagle Sandstone, central Montana uplift

    SciTech Connect

    Rice, D.D.; Gautier, D.L.; Shurr, G.W.

    1983-08-01

    The Upper Cretaceous Eagle Sandstone of central Montana was deposited during a general eastward progradation of the western shoreline of the narrow, north-south-trending Western Interior epicontinental seaway. Cordilleran highlands to the west were episodically uplifted, and provided the main source for sediments deposited in the seaway. On the Central Montana uplift, the lower member of the Eagle consists predominantly of very fine-grained sandstone, which is exposed as a thick (average 100 ft, 30 m), continuous topographic rim. This sandstone gradationally overlies shales of the Telegraph Creek Formation. Within the rim, resistant beds and concretions of calcite-cemented sandstone define several smaller units, which can be traced laterally over distances of several miles. These units maintain fairly uniform thicknesses from north to south. However, in an east-west direction, the units thin, are imbricated, and become younger to the west. The lenses in the lower member are interpreted as landward-prograding (westward) sand ridges that were deposited on the inner shelf at distances of tens of miles from the shoreline. Laterally equivalent coastal sandstones of the Virgelle Sandstone Member prograded seaward (eastward) at this same time. The lenses are elongated in a north-south direction, generally parallel to the coast. However, the exact geometry of individual ridges is unknown. After bypassing the shoreface zone, the sand probably was transported parallel to the shoreline by geostrophic currents driven by wind-forcing. Storm waves reworked the upper, seaward-facing slopes of the ridges, whereas landward-facing parts of the ridges were more protected and subjected to bioturbation.

  6. Alisitos Formation calcareous facies - Early Cretaceous episode of tectonic calm

    SciTech Connect

    Suarez-Vidal, F.

    1986-04-01

    The Alisitos Formation (Aptian-Albian), shaped as a marine volcanic arc, crops out along the western side of Baja California bounding the Peninsula Range batholith. Lithologically, this formation is formed by volcanic breccias, porphyritic flows, biohermal limestones, and tuffaceous and pyroclastic sediments. The distribution of the different facies depends on the nature of volcanism and the distance from a volcanic center, although the presence of massive biohermal limestone indicates that in the Early Cretaceous (during tectonic episodes), the volcanic activity decreased to the level that the environmental conditions were favorable for the development of an organic barrier reef behind an island arc. Such conditions pertained south of the Agua Blanca fault and extended to El Arco, Baja California. Based on field observation and petrologic analysis in the Alisitos limestone, an attempt has been made to re-create the environmental condition in the Punta China and San Fernando, Baja California, sites.

  7. Alisitos Formation, calcareous facies: Early Cretaceous episode of tectonic calm

    SciTech Connect

    Suarez-Vidal, F.

    1986-07-01

    The Alisitos Formation (Aptian-Albian), shaped as a marine volcanic arc, crops out along the western side of the peninsula of Baja California bounding the Peninsular Range batholith. Lithologically, this formation is formed by volcanic-breccias, porphyritic flows, biohermal limestones, and tuffaceous and pyroclastic sediments. The distribution of the different facies depends on the nature of volcanism and the distance from a volcanic center, although the presence of massive biohermal limestone indicates that in the Early Cretaceous (during the tectonic episodes), the volcanic activity decreased to the level that the environmental conditions were favorable for the development of an organic reef barrier, behind an island arc. Such conditions existed south of the Agua Blanca fault and extended to El Arco, Baja California. Based upon field observations and petrological analysis of the Alisitos limestone, an attempt is made to recreate the environmental condition in the Punta China and San Fernando, Baja California, sites.

  8. Stratigraphic Analysis of Upper Cretaceous Rocks in the Mahajanga Basin, Northwestern Madagascar: Implications for Ancient and Modern Faunas.

    PubMed

    Rogers; Hartman; Krause

    2000-05-01

    Upper Cretaceous strata of the Mahajanga Basin, northwestern Madagascar, yield some of the most significant and exquisitely preserved vertebrate fossils known from Gondwana. The sedimentology of these strata and their stratigraphic relations have been the focus of renewed geological investigations during the course of five expeditions since 1993. We here designate stratotypes and formalize the terrestrial Maevarano Formation, with three new members (Masorobe, Anembalemba, Miadana), and the overlying marine Berivotra Formation. The Maevarano Formation accumulated on a broad, semiarid alluvial plain bounded to the southeast by crystalline highlands and to the northwest by the Mozambique Channel. The Berivotra Formation was deposited in an open marine setting that evolved from a clastic- to a carbonate-dominated shelf, resulting in deposition of the overlying Betsiboka limestone of Danian age. New stratigraphic data clearly indicate that the Maevarano Formation correlates, at least in part, with the Maastrichtian Berivotra Formation, and this in turn indicates that the most fossiliferous portions of the Maevarano Formation are Maastrichtian in age, rather than Campanian as previously reported. This revised age for the Maevarano vertebrate assemblage indicates that it is approximately contemporaneous with the vertebrate fauna recovered from the Deccan basalt volcano-sedimentary sequence of India. The comparable age of these two faunas is significant because the faunas appear to be more similar to one another than either is to those from any other major Gondwanan landmass. The revised age of the Maevarano Formation, when considered in the light of our recent fossil discoveries, further indicates that the ancestral stocks of Madagascar's overwhelmingly endemic modern vertebrate fauna arrived on the island in post-Mesozoic times. The basal stocks of the modern vertebrate fauna are conspicuously absent in the Maevarano Formation. Finally, the revised age of the Maevarano

  9. Stratigraphic Analysis of Upper Cretaceous Rocks in the Mahajanga Basin, Northwestern Madagascar: Implications for Ancient and Modern Faunas.

    PubMed

    Rogers; Hartman; Krause

    2000-05-01

    Upper Cretaceous strata of the Mahajanga Basin, northwestern Madagascar, yield some of the most significant and exquisitely preserved vertebrate fossils known from Gondwana. The sedimentology of these strata and their stratigraphic relations have been the focus of renewed geological investigations during the course of five expeditions since 1993. We here designate stratotypes and formalize the terrestrial Maevarano Formation, with three new members (Masorobe, Anembalemba, Miadana), and the overlying marine Berivotra Formation. The Maevarano Formation accumulated on a broad, semiarid alluvial plain bounded to the southeast by crystalline highlands and to the northwest by the Mozambique Channel. The Berivotra Formation was deposited in an open marine setting that evolved from a clastic- to a carbonate-dominated shelf, resulting in deposition of the overlying Betsiboka limestone of Danian age. New stratigraphic data clearly indicate that the Maevarano Formation correlates, at least in part, with the Maastrichtian Berivotra Formation, and this in turn indicates that the most fossiliferous portions of the Maevarano Formation are Maastrichtian in age, rather than Campanian as previously reported. This revised age for the Maevarano vertebrate assemblage indicates that it is approximately contemporaneous with the vertebrate fauna recovered from the Deccan basalt volcano-sedimentary sequence of India. The comparable age of these two faunas is significant because the faunas appear to be more similar to one another than either is to those from any other major Gondwanan landmass. The revised age of the Maevarano Formation, when considered in the light of our recent fossil discoveries, further indicates that the ancestral stocks of Madagascar's overwhelmingly endemic modern vertebrate fauna arrived on the island in post-Mesozoic times. The basal stocks of the modern vertebrate fauna are conspicuously absent in the Maevarano Formation. Finally, the revised age of the Maevarano

  10. Thermochronology of Upper Cretaceous and Paleocene Deposits in the Central Cordilleran Foreland Basin

    NASA Astrophysics Data System (ADS)

    Painter, C. S.; Carrapa, B.; DeCelles, P. G.

    2011-12-01

    Since the mid-1980's the significance of coarse-grained fluvial deposits in distal foreland basins has been hotly debated. In one school of thought such deposits represent the stratigraphic signature of tectogenic topographic rejuvenation in the thrust belt during episodes of thrust propagation. More recently such deposits have been interpreted to indicate thrust belt tectonic quiescence and erosionally driven isostatic rebound. One way to address this issue is to investigate the time span between source exhumation and sedimentation (i.e. lag time); coarse sediment produced and deposited during a period of rapid thrust propagation should exhibit short lag times, whereas coarse sediment produced by post-tectonic isostatic rebound should have longer lag times. We sampled coarse-grained proximal units in the Sevier thrust belt in Utah and their distal equivalents up to 300 km east of the thrust front, and generated detrital apatite fission track (AFT) and zircon (U-Th)/He (ZHe) ages. In the proximal foreland, the Campanian Price River Formation and the Maastrichtian to Paleocene North Horn Formation in the Charleston-Nebo salient of north-central Utah were sampled in order to, (1) identify the thermochronometer that most effectively records the source exhumation and, (2) measure lag times in foreland basin units of the proximal part of the foreland basin. ZHe ages from the Price River and North Horn Formations, as well as their distal equivalents, are discordant, indicating that the system was not fully reset. This suggests that these strata never experienced T> ~180 °C; or, it could be that α-damage has contributed to He retention. AFT ages from these samples appear to be fully reset and show a consistent younging up-section. AFT cooling ages for the upper Campanian Price River Formation are 79.8 ± 6.3 Ma in the lower part of the formation and 74.5 ± 6.4 Ma higher up in the section. The Maastrichtian to Paleocene North Horn Formation, which is separated from the

  11. Late Cretaceous volcanism in south-central New Mexico: Conglomerates of the McRae and Love Ranch Formations

    SciTech Connect

    Chapman-Fahey, J.L.; McMillan, N.J.; Mack, G.H.; Seager, W.R. . Dept. of Geological Sciences)

    1993-04-01

    Evidence to support Late Cretaceous volcanism in south central New Mexico is restricted to a small area of 75-Ma-old andesitic rocks at Copper Flats near Hillsboro, and volcanic clasts in the McRae (Late Cretaceous/Paleocene ) and Love Ranch (Paleocene/Eocene). Formations located in the Jornada del Muerto basin east and northeast of the Caballo Mountains. Major and trace element data and petrographic analysis of 5 samples from Copper Flats lavas and 40 samples of volcanic clasts from the McRae and Love Ranch conglomerates will be used to reconstruct the Cretaceous volcanic field. The McRae Formation consists of two members: the lower Jose Creek and the upper Hall Lake. The lowermost Love Ranch Formation is unconformable in all places on the Hall Lake Member. Stratigraphic variations in clast composition from volcanic rocks in the lower Love Ranch Formation to Paleozoic and Precambrian clasts in the upper Love Ranch Formation reflect the progressive unroofing of the Laramide Rio Grande Uplift. Volcanic clasts in the McRae and Love Ranch Formations were derived from the west and south of the depositional basin, but the source area for McRae clasts is less well constrained. Stratigraphic, chemical, and petrographic data will be used to reconstruct the volcanic complex and more clearly define magma genesis and metasomatism associated with Laramide deformation.

  12. Chapter 2: 2003 Geologic Assessment of Undiscovered Conventional Oil and Gas Resources in the Upper Cretaceous Navarro and Taylor Groups, Western Gulf Province, Texas

    USGS Publications Warehouse

    Condon, S.M.; Dyman, T.S.

    2006-01-01

    The Upper Cretaceous Navarro and Taylor Groups in the western part of the Western Gulf Province were assessed for undiscovered oil and gas resources in 2003. The area is part of the Smackover-Austin-Eagle Ford Composite Total Petroleum System. The rocks consist of, from youngest to oldest, the Escondido and Olmos Formations of the Navarro Group and the San Miguel Formation and the Anacacho Limestone of the Taylor Group (as well as the undivided Navarro Group and Taylor Group). Some units of the underlying Austin Group, including the 'Dale Limestone' (a term of local usage that describes a subsurface unit), were also part of the assessment in some areas. Within the total petroleum system, the primary source rocks comprise laminated carbonate mudstones and marine shales of the Upper Jurassic Smackover Formation, mixed carbonate and bioclastic deposits of the Upper Cretaceous Eagle Ford Group, and shelf carbonates of the Upper Cretaceous Austin Group. Possible secondary source rocks comprise the Upper Jurassic Bossier Shale and overlying shales within the Upper Jurassic to Lower Cretaceous Cotton Valley Group, Lower Cretaceous marine rocks, and the Upper Cretaceous Taylor Group. Oil and gas were generated in the total petroleum system at different times because of variations in depth of burial, geothermal gradient, lithology, and organic-matter composition. A burial-history reconstruction, based on data from one well in the eastern part of the study area (Jasper County, Tex.), indicated that (1) the Smackover generated oil from about 117 to 103 million years ago (Ma) and generated gas from about 52 to 41 Ma and (2) the Austin and Eagle Ford Groups generated oil from about 42 to 28 Ma and generated gas from about 14 Ma to the present. From the source rocks, oil and gas migrated upsection and updip along a pervasive system of faults and fractures as well as along bedding planes and within sandstone units. Types of traps include stratigraphic pinchouts, folds, faulted

  13. Reproductive and vegetative organs with affinities to Haloragaceae from the Upper Cretaceous Huepac Chert Locality of Sonora, Mexico.

    PubMed

    Hernández-Castillo, G R; Cevallos-Ferriz, S R

    1999-12-01

    From the Upper Cretaceous (Maastrichtian-Campanian) Huepac Chert Locality of the Tarahumara Formation, a new extinct aquatic plant of the Haloragaceae (Subclass: Rosidae), Tarahumara sophiae Hernández-Castillo and Cevallos-Ferriz, is presented. It is reconstructed on the basis of both reproductive and vegetative organs preserved in chert. Its description and comparison with extant plants are based on the analysis of 350 permanent slides made with thin section and peel techniques. A mosaic of anatomical and morphological characters found in the extant Myriophyllum, Meziella, and Haloragodendron is used to characterize the new taxon. The development from flower to fruit in the fossil plant follows similar stages found in some extant species of Myriophyllum. However, a floral cup is reported for the first time in the family, and it is compared to the persistent fused sepals (terminal corona) of Meziella. This plant reconstruction increases the morphological diversity of the Haloragaceae, demonstrates the presence of a new dispersal mechanism compared with those known for the family, suggests that this lineage had originated by at least the Upper Cretaceous, and refutes the interpretation of several haloragacean Tertiary reports as representing genera of extant plants.

  14. Predicting the distribution of Upper Cretaceous aquifers using sea-level analysis and regional paleogeography, Alabama coastal plain

    SciTech Connect

    King, D.T. Jr.; Skotnicki, M.C. )

    1991-03-01

    In the inner coastal plain of Alabama, Upper Cretaceous (i.e., Santonian-Maastrichtian) stratigraphic units containing key aquifers dip south at 7m/km; the aquifers consist mainly of porous and permeable barrier-island facies (including upper-shoreface and tidal-pass sands), barrier-related sand facies (including tidal deltas and lagoonal and marine tempestite beds), and shallow-marine sand facies (including offshore bars and conglomerate sandy turbidite tongues). Confining aquitard and aquiclude facies include lagoonal silty clays, shallow-marine glauconitic clays, clayey marls, and marine chalky marls. The gross geometry, thickness, and lateral and vertical distribution of aquifer sands in both the shallow-subsurface and outcrop (i.e., recharge) area is predictable based on regional paleogeographic reconstructions and the regional Late Cretaceous relative sea-level curve. At a local scale, facies maps and shallow-subsurface correlations provide essential data for aquifer exploration and recharge-area protection. For example, in the Eutaw Formation, barrier-island and barrier-related facies developed along a curved east-west striking shoreline; aquifers include shoreline facies, tempestite beds, and turbidite sands. In the younger, northwest-striking Blufftown-Cusseta and Ripley-Providence systems, aquifers are barrier-island and barrier-related (especially tidal-delta) facies.

  15. A New Troodontid Theropod, Talos sampsoni gen. et sp. nov., from the Upper Cretaceous Western Interior Basin of North America

    PubMed Central

    Zanno, Lindsay E.; Varricchio, David J.; O'Connor, Patrick M.; Titus, Alan L.; Knell, Michael J.

    2011-01-01

    Background Troodontids are a predominantly small-bodied group of feathered theropod dinosaurs notable for their close evolutionary relationship with Avialae. Despite a diverse Asian representation with remarkable growth in recent years, the North American record of the clade remains poor, with only one controversial species—Troodon formosus—presently known from substantial skeletal remains. Methodology/Principal Findings Here we report a gracile new troodontid theropod—Talos sampsoni gen. et sp. nov.—from the Upper Cretaceous Kaiparowits Formation, Utah, USA, representing one of the most complete troodontid skeletons described from North America to date. Histological assessment of the holotype specimen indicates that the adult body size of Talos was notably smaller than that of the contemporary genus Troodon. Phylogenetic analysis recovers Talos as a member of a derived, latest Cretaceous subclade, minimally containing Troodon, Saurornithoides, and Zanabazar. MicroCT scans reveal extreme pathological remodeling on pedal phalanx II-1 of the holotype specimen likely resulting from physical trauma and subsequent infectious processes. Conclusion/Significance Talos sampsoni adds to the singularity of the Kaiparowits Formation dinosaur fauna, which is represented by at least 10 previously unrecognized species including the recently named ceratopsids Utahceratops and Kosmoceratops, the hadrosaurine Gryposaurus monumentensis, the tyrannosaurid Teratophoneus, and the oviraptorosaurian Hagryphus. The presence of a distinct troodontid taxon in the Kaiparowits Formation supports the hypothesis that late Campanian dinosaurs of the Western Interior Basin exhibited restricted geographic ranges and suggests that the taxonomic diversity of Late Cretaceous troodontids from North America is currently underestimated. An apparent traumatic injury to the foot of Talos with evidence of subsequent healing sheds new light on the paleobiology of deinonychosaurians by bolstering

  16. Neodymium isotope evolution of NW Tethyan upper ocean waters throughout the Cretaceous

    NASA Astrophysics Data System (ADS)

    Pucéat, Emmanuelle; Lécuyer, Christophe; Reisberg, Laurie

    2005-08-01

    Neodymium isotope compositions of twenty-four fish teeth, nineteen from the NW Tethys and five from different locations within the Tethys, are interpreted to reflect the evolution of Tethyan upper ocean water composition during the Cretaceous and used to track changes in erosional inputs to the NW Tethys and in oceanic circulation throughout the Cretaceous. The rather high ɛNd (up to - 7.6) of the NW Tethyan upper ocean waters recorded from the Late Berriasian to the Early Aptian and the absence of negative excursions during this interval support the presence of a permanent westward flowing Tethys Circumglobal Current (TCC). This implies that temperature variations during this time period, inferred from the oxygen isotope analysis of fish tooth enamel, were not driven by changes in surface oceanic currents, but rather by global climatic changes. The results presented here represent a significant advance over previously published Cretaceous seawater Nd isotope records. Our newly acquired data now allow the identification of two stages of low ɛNd values in the NW Tethys, during the Early Albian-Middle Albian interval (down to - 10) and the Santonian-Early Campanian (down to - 11.4), which alternate with two stages of higher ɛNd values (up to - 9) during the Late Albian-Turonian interval and the Maastrichtian. Used in conjunction with the oxygen isotope record, the fluctuations of ɛNd values can be related to major climatic, oceanographic, and tectonic events that appeared in the western Tethyan domain.

  17. Sequence stratigraphy of the Jurassic-Cretaceous Morrison and Cedar Mountain Formations, NE Utah--NW Colorado

    SciTech Connect

    Currie, B.S. . Dept. of Geological Sciences)

    1993-04-01

    The Jurassic-Cretaceous Morrison and Cedar Mountain of NE Utah and NW Colorado record nonmarine deposition during early development of the Cordilleran foreland basin. Contained within these formations are three distinct depositional sequences that represent changes in sedimentary architecture due to fluctuations in development of basin accommodation. The first of these sequences comprises the Oxfordian transition from marine to nonmarine sedimentation. Morrison Formation marginal marine and nonmarine facies prograded across shallow marine facies of the Stump Formation (Redwater Member), during a period of increased accommodation. The base of the second depositional sequences within the Morrison Formation was produced by a decrease in regional accommodation. The Cretaceous Cedar Mountain Formation unconformably overlies the Morrison Formation and its base marks the lower boundary of the third depositional sequence. The unconformity surface represents a decrease in regional accommodation and is marked by fluvial incision and evidence of subaerial exposure and intense weathering of the upper Brushy Basin Member. Increased basin accommodation during the early Cretaceous (Aptian-Albian ) resulted in valley fill deposition of the braided fluvial Buckhorn Conglomerate Member of the Cedar Mountain Formation. This conglomerate is overlain by Cedar Mountain anastomosing fluvial and lacustrine facies which were deposited during continued accommodation development. The Sequence is capped unconformity by the Albian-Cenomanian Dakota Formation.

  18. Flow of formation waters in the cretaceous-miocene succession of the Llanos basin, Colombia

    SciTech Connect

    Villegas, M.E.; Ramon, J.C.; Bachu, S.; Underschultz, J.R.

    1994-12-01

    This study presents the hydrogeological characteristics and flow of formation waters in the post-Paleozoic succession of the Llanos basin, a mainly siliciclastic foreland sub-Andean sedimentary basin located in Columbia between the Cordillera Oriental and the Guyanan Precambrian shield. The porosity of the sandy formations is generally high, in the range of 16-20% on average, with a trend of decreasing values with depth. Permeabilities are also relatively high, in the 10{sup 2} and 10{sup 3} md range. THe salinity (total dissolved solids) of formation waters is generally low, in the 10,000-20,000 mg/L range, suggesting that at least some strata in the basin have been flushed by metoeoric water. The shaly units in the sedimentary succession are weak aquitards in the eastern and southern parts of the basin, but are strong in the central-western part. The pressure in the basin is close to or slightly subdepth, particularly in the central-western area. The flow of formation waters in the upper units is driven mainly by topography from highs in the southwest to lows in the northeast. Local systems from the foothills and from local topographic highs in the east feed into this flow system. The flow of formation waters in the lower units is driven by topography only in the southern, eastern, and northern parts of the basin. In the central-western part, the flow is downdip toward the thrust-fold belt, driven probably by pore-space rebound induced by erosional unloading, which also is the cause of underpressuring. Hydrocarbons generated in the Cretaceous organic-rich, shaly Gacheta Formation probably have migrated updip and to the north-northeast, driven by buoyancy and entrained by the topography-driven flow of formation waters in Cretaceous-Oligocene strata in the central-western part of the basin could have created conditions for hydrodynamic entrapment of hydrocarbons.

  19. Revision of middle Proterozoic Yellowjacket Formation, central Idaho, and revision of Cretaceous Slim Sam Formation, Elkhorn mountains area, Montana

    USGS Publications Warehouse

    Tysdal, Russell G.

    2000-01-01

    The Yellowjacket Formation is restricted to the strata originally assigned to it by Ross (1934). The Yellowjacket, the conformably overlying Hoodoo Quartzite, and succeeding unnamed argillaceous quartzite unit form a genetically related sequence that lies in a structural block delimited on the northeast by the Iron Lake fault. Directly northeast of the fault, strata currently assigned by others to the lower subunit of the Yellowjacket are correlated with the Apple Creek Formation in the Lemhi Range. Mapping in the western part of the Lemhi Range shows that the Apple Creek Formation lies depositionally above the Big Creek Formation and that no rocks of the Yellowjacket-Hoodoo unnamed unit stratigraphic sequence are present. In contrast, in the area of the Yellowjacket mapped by Ross (1934) and the area directly northeast of the Iron Lake Fault, the Big Creek Formation is absent, even though it is 2,700 m thick in the Lemhi Range. These data indicate that the Iron Lake Fault juxtaposed the Yellowjacket-Hoodoo-unnamed unit sequence against non-Yellowjacket strata to the northeast. The Upper Cretaceous Slim Sam Formation of the Elkhorn Mountains area is revised. Strata of the lower part are correlated with the regionally recognized marine Telegraph Creek Formation and the overlying marine to marginal marine Eagle Sandstone. Only lower strata of the Eagle are present in the study area and they are preserved discontinously. The nonmarine volcanic and volcaniclastic rocks of the upper part of the Slim Sam as originally defined retain the name Slim Sam Formation. These rocks, mainly of sedimentary origin, are genetically related to the Elkhorn Mountains Volcanics. The lower contact of the Slim Sam (restricted) is unconformable above the Eagle Sandstone or more commonly above the Telegraph Creek Formation. The upper contact is conformable with the Elkhorn Mountains Volcanics.

  20. Lower Cretaceous and Upper Jurassic oil reservoirs of the updip basement structure play: Southwest Alabama

    SciTech Connect

    Mink, R.M.; Mancini, E.A.

    1995-10-01

    Exploration for Lower Cretaceous and Upper Jurassic reservoirs associated with updip basement structures currently is the most active exploratory oil play in Alabama. High initial flow rates, on the order of hundreds to thousands of barrels of oil per day, are commonly encountered at depths between 8,200 and 14,500 feet. Fifty-one fields have been established and 25 million barrels of oil have been produced from these fields developed in Lower Cretaceous Hosston and Upper Jurassic Haynesville, Smackover, and Norphlet reservoirs. Production from Smackover carbonates began at Toxey field in 1967 and from Haynesville sandstones at Frisco City field in 1986. As of September 1994, Smackover wells averaged 88 barrels of oil per day and Haynesville wells averaged 284 barrels of oil per day. In 1994, production was established in the Norphlet at North Excel field and in the Hosston at Pleasant Home field. Reservoirs in the updip basement structure play cluster in three distinct areas; (1) a western area on the Choctaw ridge complex, (2) a central area on the Conecuh ridge complex, and (3) an eastern area in the Conecuh embayment. Reservoir lithologies include Smackover limestones and dolostones and Hosston, Haynesville, Smackover, and Norphlet sandstones. Hydrocarbon traps are structural or combination traps where reservoirs occur on the flanks or over the crests of basement palohighs. An understanding of the complex reservoir properties and trap relationships is the key to successful discovery and development of Lower Cretaceous and Upper Jurassic oil reservoirs of the updip basement structure play of southwest Alabama.

  1. Upper Cretaceous Shannon Sandstone reservoirs, Powder River Basin, Wyoming: evidence for organic acid diagenesis?

    USGS Publications Warehouse

    Hansley, P.L.; Nuccio, V.F.

    1992-01-01

    Comparison of the petrology of shallow and deep oil reservoirs in the Upper Cretaceous Shannon Sandstone Beds of the Steele Member of the Cody Shale strongly suggests that organic acids have had a more significant impact on the diagenetic alteration of aluminosilicate grains and carbonate cements in the deep reservoirs than in the shallow reservoirs. Vitrinite reflectance and Rock-Eval measurements, as well as the time-temperature index and kinetic modeling, indicate that deep reservoirs have been subjected to maximum temperatures of approximately 110-120??C, whereas shallow reservoirs have reached only 75??C. -from Authors

  2. Vertebrate fossils and trace fossils in Upper Jurassic-Lower cretaceous red beds in the Atacama region, Chile

    NASA Astrophysics Data System (ADS)

    Bell, C. M.; Suárez, M.

    Pterosaur, dinosaur, and crocodile bones are recorded here for the first time in Upper Jurassic-Lower Cretaceous red beds in the Atacama region east of Copiapó, Chile. Trace fossils produced by vertebrate animals include the footprints of theropod dinosaurs and the depressions of sandstone laminae interpreted as burrows and foot impressions. The fossils occur in the 1500-meter-thick Quebrada Monardes Formation, which consists predominantly of the aeolian and alluvial deposits of a semi-arid terrestrial environment. Vertebrate fossils are very rare in Chile. Dinosaur bones and footprints have previously been recorded at only seven locations, and pterosaur remains at only one location. The newly discovered dinosaur bones are the oldest to be described in Chile.

  3. Early Cretaceous continental sedimentation in the Coastal Cordillera (Atajaña Formation), Northern Chile

    NASA Astrophysics Data System (ADS)

    Fuentes, G.; Garcia, M.; Sepulveda, F.; Vasquez, P.

    2013-12-01

    Early Cretaceous continental sedimentation development at the Coastal Cordillera of northern Chile has been described in a broad sense. The Atajaña Formation represents this continental sedimentation, south of Arica (18°30S), where it exposes mostly as an elongated swath oriented N70°E, forming a 20 km long and 8 km wide area of outcrop. Northward, these deposits occur as isolated outcrops at the bottom of Chiza, Camarones, Vitor and Azapa valleys. The Atajaña succession was deposited in apparent angular unconformity over Cuya Formation (Middle-Late Jurassic) and Chiza Formation (Bajocian-Oxfordian). The Atajaña Formation is overlain, conformable and transitional, by the Blanco Formation (Aptian-Albian) and overlain in erosion unconformity by the Suca Formation (upper Early Cretaceous). Angular unconformity contact between Atajaña Formation and Cenozoic units (Azapa Formation and alluvial deposits) is exposed at previously named valleys. In the Camarones valley, the Atajaña Formation unconformably overlies Middle to Late Jurassic intrusive rocks. In this work, the Atajaña Formation is divided in three facies associations, exposed close to Atajaña hill and Chiza valley (Kia1, Kia2 y Kia2a). Reddish conglomerates and sedimentary breccias facies (Kia1) consists of an up to 850 m thick. These rocks are massive, polymictic and poorly-sorted, and form laterally extensive beds. Clasts are mostly composed by diorites, monzodiorites, grayish fine sandstones, fine calcareous sandstones, limestones, volcarenites and porphyric andesites. Facies Kia1 includes interbedded red calcareous sandstones and siltstones, some of them displaying low-angle cross bedding. Facies Kia2 consists of an up to 570 m thick of red sandstone and siltstone, interbedded with conglomerates. This well stratified succession, parallel bedded and minor cross bedded, form continuous beds with subrounded and well-sorted clasts. Previous authors described dessication cracks in the red siltstones

  4. Chemostratigraphy of Upper Cretaceous chalk sequences in Norwegian-Danish basin and North Sea Central Trough

    SciTech Connect

    Joergensen, N.O.

    1987-05-01

    Geochemical studies of subsurface sections and outcrops in the Upper Cretaceous chalk sequences from the Norwegian-Danish basin and the North Sea Central Trough have resulted in a detailed chemostratigraphy for these strata. The most applicable chemostratigraphic markers are based on the distribution of strontium, magnesium, manganese, the /sup 13/C//sup 12/C ratio, and the variations in the carbonate contents. It is demonstrated that the chemostratigraphic approach is valid at two levels: (1) a superior chemostratigraphy in which deep-sea cores from the Atlantic Ocean and sections from western Europe are correlated on the basis of significant geochemical anomalies and long-term variations most likely induced by oceanic geochemical cycles and sea level fluctuations; (2) a subordinate but detailed intrabasinal chemostratigraphic correlation which primarily reflects the physicochemical conditions in the depositional environment. The Upper Cretaceous chemostratigraphy established in the Danish area allows a detailed correlation between relatively continuous chalk sequences in the Norwegian-Danish basin and the rather condensed and hiati-influenced sections in the oil fields of the North Sea. The results emphasize the applicability of chemostratigraphy in the subsurface exploration for hydrocarbon reservoirs in chalk.

  5. Incrusting and boring bryozoans from the Dessau Chalk Formation (Cretaceous), Little Walnut Creek, Austin, Texas

    SciTech Connect

    Morris, P.A. )

    1990-09-01

    Four sections were measured along a 1/4 mi length of Little Walnut Creek. The first section was 165 ft north of the US. 290 bridge while the fourth was 1/4 mi upstream. Structurally, the stream follows the fault in this section. Small faults can be found perpendicular to the primary fault and apparently account not only for minor variation in local dip (8{degrees}SE, parallel to 5{degrees}NW) but also for the placement of at least one tributary. Megainvertebrate exoskeletons were found to have been inhabited by incrusting bryozoans, boring bryozoans, and sponges. These fossils were found on both interior and exterior surfaces of Exogyra laeviuscula E tigrina, and interior surfaces of Inoceramus. A low-energy environment allowed exposure of megainvertebrate exoskeletons after death but also prevented fracturing. Low siltation rates also extended exoskeleton availability after organismic death. The nonboring bryozoans are cheilostomes and at least one species, Pyripora, has been described from the Kansas Cretaceous as well as European Cretaceous sites. The boring bryozoans are primarily represented by Terebripora sp. In conclusion, this section of Dessau Chalk Formation, Upper Austin Group, was mostly a low-energy environment, shallow, limy mud platform. This substrate was probably not stable enough for bryozoan colonization as unattached colonies have not been found in sediments. Therefore, bryozoan substrates were limited to living and dead Exogyra sp. and dead Inoceramus sp. exoskeletons.

  6. Integrated foraminiferal biostratigraphy and chemostratigraphy of the querecual formation (Cretaceous), Eastern Venezuela

    USGS Publications Warehouse

    Crespo De Cabrera, S.; Sliter, W.V.; Jarvis, I.

    1999-01-01

    An integrated foraminiferal biostratigraphy and chemostratigraphy is presented for the Lower to Upper Cretaceous Querecual Formation exposed on Chimana Grande Island, Eastern Venezuela. The formation consists of >450 m alternating foraminiferal and organic-rich carbonates and laminated mudrocks, and is considered the main hydrocarbon source rock for the eastern Venezuela Basin. Biostratigraphic resolution within the Querecual Formation is poor, due to a paucity of keeled planktonic foraminifera and impoverished benthic faunas. Deposition occurred in a bathyal environment, with dysaerobic or anoxic bottom waters resulting from high rates of surface productivity associated with an upwelling environment. Biostratigraphic evidence indicates that the Querecual Formation ranges from the upper Albian Rotalipora ticinensis Zone to the Santonian Dicarinella asymetrica Zone. Iron and Al contents fall through the Albian-Cenomanian indicating a progressive decrease in the detrital supply, driven by rising eustatic sea level. A Ca profile demonstrates variations in carbonate production and dissolution. High total organic carbon (TOC) intervals occur in the upper Albian to mid-Cenomanian and Turonian, and high Ba/Al and Si/Al ratios characterize mid-Cenomanian and younger sediments. Variations in these elements primarily reflect changes in marine productivity, but are also affected by diagenetic processes. A stable carbon isotope curve established from analysis of organic matter (??13Corg) correlates well with published ??13C curves for carbonates from England and Italy. The Cenomanian/Turonian boundary cannot be identified using planktonic foraminifera, because key taxa are absent, but the base of the Turonian is clearly indicated by a sharp fall in ??13C immediately above a major positive excursion. The bottom of the Coniacian is placed below a ??13C minimum, towards the base of the Dicarinella concavata Zone. Combined with the foraminiferal data, the isotopic data enable much

  7. Late Cretaceous stratigraphy of the Upper Magdalena Basin in the Payandé-Chaparral segment (western Girardot Sub-Basin), Colombia

    NASA Astrophysics Data System (ADS)

    Barrio, C. A.; Coffield, D. Q.

    1992-02-01

    The Cretaceous section on the western margin of the Girardot Sub-Basin, Upper Magdalena Valley, is composed of the Lower Sandstone (Hauterivian-Barremian?), Tetuán Limestone (pre-Aptian?), and Bambuca Shale (pre-Aptian?), and the following formations: Caballos (Aptian-Albian), Villeta (Albian-Campanian), Monserrate (Campanian-Maastrichtian), and Guaduas (Maastrichtian-Paleocene). The Lower Sandstone is composed of quartz arenites with abundant calcareous cement; the Tetuúan Limestone is a succession of fossiliferous limestones and calcareous shales; the the Bambuca Shale is composed of black shales that grade upward to micritic limestones and calcarenites. The Caballos Formation comprises three members: a lower member of quartz arenites, a middle member of black shales and limestones, and an upper member of crossbedded, coarsening-upward quartz arenites. The Villeta Formation is a sequence of shales intercalated with micritic limestones and calcarenites. Two levels of chert (Upper and Lower Chert) are differentiated within the Villeta Formation throughout the study area, with a sandstone unit (El Cobre Sandstone) to the north. The Monserrate Formation is composed of quartz arenites, with abundant crossbedding, and locally of limestone breccias and coarse-grained fossiliferous packstones. The Guaduas Formation is a monotonous succession of red shales and lithic sandstones. Our data suggest three major transgressive-regressive cycles in the Girardot Sub-Basin. The first cycle (Hauterivian?-lower Aptian) is represented by the Lower Sandstone-Tetuán-Bambuca-lower Caballos succession, the second cycle (Aptian-Albian) by the middle-upper Caballos members, and the third cycle (Albian-Paleocene) by the lower Villeta-Monserrate-Guaduas succession. Previous studies proposed a eustatic control during deposition of the Upper Cretaceous in the Upper Magdalena Valley. The lowermost transgressive-regressive cycle was not previously differentiated in the study area, and this

  8. Lower Tertiary and Upper Cretaceous source rocks in Louisiana and Mississippi: Implications to Gulf of Mexico crude oil

    SciTech Connect

    Sassen, R. )

    1990-06-01

    The Lower Tertiary Sparta Formation, Wilcox Group, and the Midway Group in southern Louisiana include organic-rich source facies that generate crude oil at relatively high thermal maturities. The Wilcox Group is an important source of Wilcox crude oil, and regional kerogen variations explain two crude oil subfamilies. Wilcox crude oils in downdip areas of southern Louisiana migrated short distances, but long-range lateral migration (about 150 km) best explains Wilcox crude oils far updip from mature source rocks. Crude oils in Oligocene and younger reservoirs in southern Louisiana migrated vertically from deep lower Tertiary source rocks. Some crude oils in Upper Cretaceous Tuscaloosa reservoirs were emplaced by long-range lateral migration from Tuscaloosa source rocks. Given little evidence of upper Tertiary source rocks and the overmaturity problems of Mesozoic source rocks, most crude oils in upper Tertiary and Pleistocene reservoirs of the Gulf continental shelf are best explained by vertical migration from deep lower Tertiary source rocks. Even so, it is simplistic to assume an exclusive lower Tertiary origin. Many Tertiary and Pleistocene crude oils of this study probably include an overprint of high-maturity hydrocarbons from Mesozoic sources. 12 figs., 7 tabs.

  9. From Source to Sink: Exhumation of the North America Cordillera Revealed by Multi-dating of Detrital Minerals from Upper Jurassic-Upper Cretaceous Sevier Foreland Basin

    NASA Astrophysics Data System (ADS)

    Painter, C. S.; Carrapa, B.; DeCelles, P. G.; Gehrels, G. E.; Thomson, S. N.

    2013-12-01

    We sampled twenty-two Late Jurassic to Late Cretaceous syn-orogenic conglomerate clasts in proximal units in the Sevier fold-thrust belt and their distal sandstone equivalents up to 300 km east of the thrust front, in Utah, Colorado, Wyoming, and South Dakota. To better constrain depositional ages, these samples were analyzed using detrital zircon U-Pb (DZ U-Pb) geochronology. To identify a thermochronometer that measures source exhumation in the North America Cordillera, both zircon (U-Th)/He and apatite fission track (AFT) thermochronology was utilized, on both the conglomerate cobbles and sandstone (detrital) samples. Eleven samples were analyzed with zircon (U-Th)/He; however, discordant ages in the conglomerate cobble samples suggest that this system was not fully reset and never experienced T> ~180 °C in the source stratigraphy during the Sevier orogeny. Eleven other samples are analyzed using apatite fission track thermochronology (AFT); AFT ages are generally similar or older than depositional ages indicating that the detrital ages record source exhumation signals, and that exhumation depth corresponds to T>~120 °C. In order to test whether or not the youngest cooling AFT age population represents a source exhumation signal or a co-magmatic signal we here performed double dating of the detrital AFT samples using apatite U-Pb thermochronology. Maximum depositional ages using DZ U-Pb match existing age controls on basin stratigraphy. Our study shows that AFT is an effective thermochronometer to detect source exhumation for Cretaceous foreland stratigraphy in the western U.S.A. Lag-times (i.e. the difference between the source exhumation age and depositional age) are ~0 to 5 Myr with relatively steady-state to slightly increasing exhumation rates suggesting orogenic growth at this time. The very short lag times also indicate limited to no storage time between source and sink. The AFT lag time of the Early Cretaceous Kelvin Formation is ~5 Myr and represents

  10. Mesozoic (Upper Jurassic-Lower Cretaceous) deep gas reservoir play, central and eastern Gulf coastal plain

    USGS Publications Warehouse

    Mancini, E.A.; Li, P.; Goddard, D.A.; Ramirez, V.O.; Talukdar, S.C.

    2008-01-01

    The Mesozoic (Upper Jurassic-Lower Cretaceous) deeply buried gas reservoir play in the central and eastern Gulf coastal plain of the United States has high potential for significant gas resources. Sequence-stratigraphic study, petroleum system analysis, and resource assessment were used to characterize this developing play and to identify areas in the North Louisiana and Mississippi Interior salt basins with potential for deeply buried gas reservoirs. These reservoir facies accumulated in Upper Jurassic to Lower Cretaceous Norphlet, Haynesville, Cotton Valley, and Hosston continental, coastal, and marine siliciclastic environments and Smackover and Sligo nearshore marine shelf, ramp, and reef carbonate environments. These Mesozoic strata are associated with transgressive and regressive systems tracts. In the North Louisiana salt basin, the estimate of secondary, nonassociated thermogenic gas generated from thermal cracking of oil to gas in the Upper Jurassic Smackover source rocks from depths below 3658 m (12,000 ft) is 4800 tcf of gas as determined using software applications. Assuming a gas expulsion, migration, and trapping efficiency of 2-3%, 96-144 tcf of gas is potentially available in this basin. With some 29 tcf of gas being produced from the North Louisiana salt basin, 67-115 tcf of in-place gas remains. Assuming a gas recovery factor of 65%, 44-75 tcf of gas is potentially recoverable. The expelled thermogenic gas migrated laterally and vertically from the southern part of this basin to the updip northern part into shallower reservoirs to depths of up to 610 m (2000 ft). Copyright ?? 2008. The American Association of Petroleum Geologists. All rights reserved.

  11. Tectonic significance of Upper Cretaceous alluvial-fan deposits in the Peninsular Ranges forearc basin complex, Baja California (Mexico)

    SciTech Connect

    Fulford, M.; Busby-Spera, C. )

    1990-05-01

    Recent evidence suggests that forearc basins, previously depicted as broad downwarps, may experience syndepositional faulting and/or folding. The upper Campanian El Gallo Formation, which was deposited along the northern margin of the Rosario embayment of the peninsula Ranges forearc basin complex, records tilting of the underlying arc massif basement contemporaneous with dissection of the arc source terrane. The La Escarpa member at the base of the El Gallo Formation consists of a 100-180-m thick upward-fining sequence, interpreted as a retrogradational proximal to distal alluvial-fan deposit. Overlying the La Escarpa member is the 1,000-m thick El Disecado member, which lies at the top of the El Gallo Formation and consists of sandy fluvial deposits. Conglomerate clast counts from the La Escarpa member and point-count data from sandstones throughout the El Gallo Formation show an upsection increase in granitic and metasedimentary rock fragments relative to volcanic/metavolcanic rock fragments, reflecting unroofing and progressive headward erosion of the source terranes in the Peninsular Ranges. Paleocurrent data from the La Escarpa and El Disecado members suggest a rotation of approximately 110{degree} with time, from west-northwesterly to southerly, reflecting tilting of the basin floor. This may have been accomplished by downdropping along an east-west-trending fault that divided the Rosario embayment into separate subbasins during the Cretaceous.

  12. Stratigraphy and sedimentology of the Upper Cretaceous (Campanian) Anacacho Limestone, Texas, USA

    USGS Publications Warehouse

    Swezey, C.S.; Sullivan, E.C.

    2004-01-01

    The Upper Cretaceous Anacacho Limestone is exposed in outcrops between the cities of San Antonio and Del Rio, Texas. A detailed study of four outcrops (Blanco Creek section, Sabinal River section, Seco Creek section, Hondo Creek section) shows that the Anacacho Limestone rests on the Upson Clay (which contains fauna of early Campanian age) and is overlain by the Corsicana Marl (which contains fauna of early Maastrichtian age). An unconformity within the Anacacho Limestone is used herein to separate the limestone into a lower member and an upper member. The lower Anacacho member contains fauna of early Campanian age, whereas the upper Anacacho member contains fauna of middle Campanian age. The lower Anacacho member consists predominantly of wackestones to packstones, which are overlain by packstones to grainstones capped by the unconformity. This unconformity is interpreted as a marine flooding surface, delineating a transition from carbonate grainstones deposited in shallow water (<30 m depth) to a chalk deposited in deeper water. Above the unconformity, the upper Anacacho member is characterized by a chalk, overlain by wackestones and packstones. The uppermost section of the Anacacho Limestone consists of packstones and grainstones with abundant and diverse fossils. Most of the Anacacho Limestone developed in relatively shallow water (<50 m depth) leeward of a large carbonate build-up (possibly a rudistid reef) that now comprises the Anacacho Mountains. The environment, however, was open to marine water throughout deposition of the Anacacho Limestone. ?? 2004 Elsevier Ltd. All rights reserved.

  13. Recycled gabbro signature in Upper Cretaceous Magma within Strandja Massif: NW Turkey

    NASA Astrophysics Data System (ADS)

    Ulusoy, Ezgi; Kagan Kadioglu, Yusuf

    2016-04-01

    Basic magma intrusions within plate interiors upwelling mantle plumes have chemical signatures that are distinct from mid-ocean ridge magmas. When a basic magma interact with continental crust or with the felsic magma, the compositions of both magma changes, but there is no consensus as to how this interaction occurs. Here we analyse the mineral behavior and trace element signature of gabbroic rocks of the samples collected from the Strandja Massif. Srednogorie magmatic arc is a part of Apuseni- Banat-Timok-Srednogorie magmatic belt and formed by subduction and closure of the Tethys Ocean during Upper Cretaceous times. Upper Cretaceous magmatic rocks cutting Strandja Massif in NW Turkey belong to eastern edge of Srednogorie Magmatic arc. Upper Cretacous magmatic rocks divided into four subgroup in Turkey part of Strandja massif: (I) granitic rocks, (II) monzonitic rock, (III) syenitic rocks and (IV) gabbroic rocks. Gabbroic rocks outcropped around study area in phaneritic - equigranular texture. According to mineralogic - petrographic studies gabbros have mainly holocrystalline texture and ophitic to subophitic texture composed of plagioclase, amphibole, pyroxene, and rarely olivine and opaque minerals. Also because of special conditions there have been pegmatitic texture on mafic minerals with euhedral form up to 3 cm in size and orbicular texture which reach 15cm in size and rounded - elliptical form. Confocal Raman Spectroscopy studies reveals that plagioclase are ranging in composition from labradorite to bytownite, the pyroxene are ranging in composition from diopside to augite acting with uralitization processes and the olivine are generally in the composition of forsterite. Petrographic and mineralogical determination reveals some metasomatic magmatic epidote presence. Confocal Raman Spectroscopy studies on anhydrous minerals within gabbroic rocks shows affect of hydrous process because of magma mixing. The gabbroic rocks have tholeiitic and changed towards

  14. A new pterosaur (Pterodactyloidea: Azhdarchidae) from the Upper Cretaceous of Morocco.

    PubMed

    Ibrahim, Nizar; Unwin, David M; Martill, David M; Baidder, Lahssen; Zouhri, Samir

    2010-05-26

    The Kem Kem beds in South Eastern Morocco contain a rich early Upper (or possibly late Lower) Cretaceous vertebrate assemblage. Fragmentary remains, predominantly teeth and jaw tips, represent several kinds of pterosaur although only one species, the ornithocheirid Coloborhynchus moroccensis, has been named. Here, we describe a new azhdarchid pterosaur, Alanqa saharica nov. gen. nov. sp., based on an almost complete well preserved mandibular symphysis from Aferdou N'Chaft. We assign additional fragmentary jaw remains, some of which have been tentatively identified as azhdarchid and pteranodontid, to this new taxon which is distinguished from other azhdarchids by a remarkably straight, elongate, lance-shaped mandibular symphysis that bears a pronounced dorsal eminence near the posterior end of its dorsal (occlusal) surface. Most remains, including the holotype, represent individuals of approximately three to four meters in wingspan, but a fragment of a large cervical vertebra, that probably also belongs to A. saharica, suggests that wingspans of six meters were achieved in this species. The Kem Kem beds have yielded the most diverse pterosaur assemblage yet reported from Africa and provide the first clear evidence for the presence of azhdarchids in Gondwana at the start of the Late Cretaceous. This, the relatively large size achieved by Alanqa, and the additional evidence of variable jaw morphology in azhdarchids provided by this taxon, indicates a longer and more complex history for this clade than previously suspected.

  15. A New Pterosaur (Pterodactyloidea: Azhdarchidae) from the Upper Cretaceous of Morocco

    PubMed Central

    Ibrahim, Nizar; Unwin, David M.; Martill, David M.; Baidder, Lahssen; Zouhri, Samir

    2010-01-01

    The Kem Kem beds in South Eastern Morocco contain a rich early Upper (or possibly late Lower) Cretaceous vertebrate assemblage. Fragmentary remains, predominantly teeth and jaw tips, represent several kinds of pterosaur although only one species, the ornithocheirid Coloborhynchus moroccensis, has been named. Here, we describe a new azhdarchid pterosaur, Alanqa saharica nov. gen. nov. sp., based on an almost complete well preserved mandibular symphysis from Aferdou N'Chaft. We assign additional fragmentary jaw remains, some of which have been tentatively identified as azhdarchid and pteranodontid, to this new taxon which is distinguished from other azhdarchids by a remarkably straight, elongate, lance-shaped mandibular symphysis that bears a pronounced dorsal eminence near the posterior end of its dorsal (occlusal) surface. Most remains, including the holotype, represent individuals of approximately three to four meters in wingspan, but a fragment of a large cervical vertebra, that probably also belongs to A. saharica, suggests that wingspans of six meters were achieved in this species. The Kem Kem beds have yielded the most diverse pterosaur assemblage yet reported from Africa and provide the first clear evidence for the presence of azhdarchids in Gondwana at the start of the Late Cretaceous. This, the relatively large size achieved by Alanqa, and the additional evidence of variable jaw morphology in azhdarchids provided by this taxon, indicates a longer and more complex history for this clade than previously suspected. PMID:20520782

  16. Upper Jurassic to Lower Cretaceous(?) synorogenic sedimentary rocks in the southern Spring Mountains, Nevada

    NASA Astrophysics Data System (ADS)

    Carr, Michael D.

    1980-08-01

    A newly recognized sequence of Upper Jurassic to Lower Cretaceous(?) terrigenous rocks in the Good-springs district, Nevada, was deposited during the emplacement of the Contact thrust plate. Two facies are recognized: (1) interbedded conglomerate and sandstone derived from Mesozoic igneous and terrigenous platform rocks and (2) interbedded carbonate and sandstone-clast conglomerate, quartz sandstone, and red shale. No igneous detritus occurs in the facies with carbonate-clast conglomerate. Carbonate clasts could only have been derived from the Paleozoic carbonate sequence, which was exposed in the area by latest Jurassic to earliest Cretaceous thrusting. The age of rocks from a volcanic unit within the synorogenic sequence was determined radiometrically to be 150 ± 10 m.y. (K-Ar on biotite). The sequence was deposited disconformably on deeply eroded rocks of the early Mesozoic platform and ultimately overridden from the west by the Contact thrust plate. Information from the sequence corroborates previously reported regional data regarding the timing and nature of the Contact-Red Springs thrust event. *Present address: U.S. Geological Survey, 345 Middlefield Road, Menlo Park, California 94025

  17. Pre-, syn-, and postcollisional stratigraphic framework and provenance of upper triassic-upper cretaceous strata in the northwestern talkeetna mountains, alaska

    USGS Publications Warehouse

    Hampton, B.A.; Ridgway, K.D.; O'Neill, J. M.; Gehrels, G.E.; Schmidt, J.; Blodgett, R.B.

    2007-01-01

    Mesozoic strata of the northwestern Talkeetna Mountains are located in a regional suture zone between the allochthonous Wrangellia composite terrane and the former Mesozoic continental margin of North America (i.e., the Yukon-Tanana terrane). New geologic mapping, measured stratigraphic sections, and provenance data define a distinct three-part stratigraphy for these strata. The lowermost unit is greater than 290 m thick and consists of Upper Triassic-Lower Jurassic mafic lavas, fossiliferous limestone, and a volcaniclastic unit that collectively we informally refer to as the Honolulu Pass formation. The uppermost 75 m of the Honolulu Pass formation represent a condensed stratigraphic interval that records limited sedimentation over a period of up to ca. 25 m.y. during Early Jurassic time. The contact between the Honolulu Pass formation and the overlying Upper Jurassic-Lower Cretaceous clastic marine strata of the Kahiltna assemblage represents a ca. 20 m.y. depositional hiatus that spans the Middle Jurassic and part of Late Jurassic time. The Kahiltna assemblage may to be up to 3000 m thick and contains detrital zircons that have a robust U-Pb peak probability age of 119.2 Ma (i.e., minimum crystallization age/maximum depositional age). These data suggest that the upper age of the Kahiltna assemblage may be a minimum of 10-15 m.y. younger than the previously reported upper age of Valanginian. Sandstone composition (Q-43% F-30% L-27%-Lv-71% Lm-18% Ls-11%) and U-Pb detrital zircon ages suggest that the Kahiltna assemblage received igneous detritus mainly from the active Chisana arc, remnant Chitina and Talkeetna arcs, and Permian-Triassic plutons (Alexander terrane) of the Wrangellia composite terrane. Other sources of detritus for the Kahiltna assemblage were Upper Triassic-Lower Jurassic plutons of the Taylor Mountains batholith and Devonian-Mississippian plutons; both of these source areas are part of the Yukon-Tanana terrane. The Kahiltna assemblage is overlain

  18. The Mid-Cretaceous Frontier Formation near the Moxa Arch, southwestern Wyoming

    USGS Publications Warehouse

    Mereweather, E.A.; Blackmon, P.D.; Webb, J.C.

    1984-01-01

    The Frontier Formation in the Green River Basin of Wyoming, Utah, and Colorado, consists of sandstone, siltstone, and shale, and minor conglomerate, coal, and bentonite. These strata were deposited in several marine and nonmarine environments during early Late Cretaceous time. At north-trending outcrops along the eastern edge of the overthrust belt, the Frontier is of Cenomanian, Turonian, and early Coniacian age, and commonly is about 610 m (2,000 ft) thick. The formation in that area conformably overlies the Lower Cretaceous Aspen Shale and is divided into the following members, in ascending order: Chalk Creek, Coalville, Allen Hollow, Oyster Ridge Sandstone, and Dry Hollow. In west-trending outcrops on the northern flank of the Uinta Mountains in Utah, the Frontier is middle and late Turonian, and is about 60 m (200 ft) thick. These strata disconformably overlie the Lower Cretaceous Mowry Shale. In boreholes on the Moxa arch, the upper part of the Frontier is of middle Turonian to early Coniacian age and unconformably overlies the lower part of the formation, which is early Cenomanian at the south end and probably Cenomanian to early Turonian at the north end. The Frontier on the arch thickens northward from less than 100 m (328 ft) to more than 300 m (984 ft) and conformably overlies the Mowry. The marine and nonmarine Frontier near the Uinta Mountains, marine and mnmarine beds in the upper part of the formation on the Moxa arch and the largely nonmarine Dry Hollow Member at the top of the Frontier in the overthrust belt are similar in age. Older strata in the formation, which are represented by the disconformable basal contact of the Frontier near the Uinta Mountains, thicken northward along the Moxa arch and westward between the arch and the overthrust belt. The large changes in thickness of the Frontier in the Green River Basin were caused mainly by differential uplift and truncation of the lower part of the formation during the early to middle Turonian and

  19. Middle and upper cretaceous amber from the Taimyr Peninsula, Siberia: Evidence for a new structural sub-class of resinite

    SciTech Connect

    Anderson, K.B.

    1994-08-01

    Analysis of three amber (resinite) samples collected from Middle and Upper Cretaceous sediments in the Taimyr Peninsula, Siberia, indicates that these materials are based on copolymers of biformene (I) and communol (II). No resinites of similar structural character have previously been described and hence, these samples represent a previously unknown structural sub-class of resinite.

  20. Cretaceous anuran and dinosaur footprints from the Patuxent Formation of Virginia

    USGS Publications Warehouse

    Weems, R.E.; Bachman, J.M.

    1997-01-01

    Footprints of an anuran (gen. et sp. indet.), a theropod dinosaur (Megalosauropus sp.), and an ornithopod dinosaur (Amblydactylus sp.) have been recovered from the Lower Cretaceous Patuxent Formation in Stafford County, Virginia. These footprints are the first record of terrestrial vertebrates from Cretaceous strata in Virginia, and their discovery suggests that the scarcity of bones and teeth in the Patuxent probably is an artifact of preservation. The anuran trackway provides the oldest known direct evidence for hopping locomotion among these amphibians.

  1. Groundwater salinization survey of the Upper Cretaceous-Miocene Complexe terminal aquifer in the Sabaa Biar area of southwestern Tunisia

    NASA Astrophysics Data System (ADS)

    Mhamdi, Abdelkader; Dhahri, Ferid; Gouasmia, Mouez; Moumni, Lahmadi; Mohamed, Soussi

    2015-12-01

    An integrated hydrogeological study involving the Schlumberger depth sounding method, geological data and wells data was conducted at the Sabaa Biar area of southern Tunisia to elucidate the problem of increasing groundwater salinity within The "Complexe Terminal". The "Complexe Terminal" aquifer near Sabaa Biar region is a bi-layered aquifer comprised of fractured limestones of the Cretaceous (Campanian-Maastrichtian) Berda Formation and sandstone of the Miocene Beglia Formation. The aquifer is affected by a main NW-trending fault, which is a chemical barrier that divides the study area into eastern and western blocks delivering freshwater and saline water, respectively. The salinization of groundwater within the limestone (Campanian-Maastrichtian Berda Formation) is linked mainly to the dissolution of outcropping Coniacian-Santonian gypsum along the core of the Jebel Sidi Bouhlel anticline to the east of the study area. Meteoric water dissolves salt from outcropping gypsum, flows through the fractures networks, and recharges the fractured limestone of the upper Berda Formation. The mobilization of salts stored in the salt-rich Quaternary sediment on hillslopes and inchannels contributes also to the salinization of groundwater within the sandstone (Miocene Beglia Formation) by lateral infiltration subsequent to water drainage during the wet season. The over exploitation of water from the Miocene sandstone causes an influx of saline-rich water from the underlying limestone of the Berda Formation into the sandstone of the Beglia Formation. Other sources of salinization of groundwater (such as ascension of hypersaline water from deep aquifer along faults, and the return flow of irrigation waters in the Djerid region) have been documented in this region, but are not discussed in this paper.

  2. Opinion formation with upper and lower bounds

    NASA Astrophysics Data System (ADS)

    Yano, Ryosuke; Martin, Arnaud

    2015-12-01

    We investigate the opinion formation with upper and lower bounds. We formulate the binary exchange of opinions between two peoples under the second (or political) party using the relativistic inelastic-Boltzmann-Vlasov equation with randomly perturbed motion. In this paper, we discuss the relativistic effects on the opinion formation of peoples from the standpoint of the relativistic kinetic theory.

  3. Newly combined 40Ar/39Ar and U-Pb ages of the Upper Cretaceous timescale from Hokkaido, Japan

    NASA Astrophysics Data System (ADS)

    Gaylor, J. R.; Heredia, B. D.; Quidelleur, X.; Takashima, R.; Nishi, H.; Mezger, K.

    2011-12-01

    The main targets for GTS next project (www.gtsnext.eu) are to develop highly refined geological time scales, including the Upper Cretaceous. The Cretaceous period is characterised by numerous global anoxic events in the marine realm, rich ammonitic fossil assemblages and specialised foraminifera. However, lack of age diagnostic macro and micro fossils in the North Pacific sections has made it difficult to link these with global sections such as the Western Interior Basin (North America). Using advances with terrestrial C-isotope and planktic foraminifera records within Central Hokkaido we are able to correlate these sections globally. The Cretaceous Yezo group in Central Hokkaido comprises deep marine mudstones and turbidite sandstones interbedded with acidic volcanic tuffs. Using various sections within the Yezo group, we radiometrically dated tuffs at the main stage boundaries in the Upper Cretaceous. The samples derive from the Kotanbetsu, Shumarinai, Tiomiuchi and the Hakkin river sections, spanning the time from the Albian-Cenomanian up until the Campanian-Santonian boundaries, and were dated using 40Ar/39Ar, K/Ar and U-Pb techniques. Recent age constraints in the Hokkaido counterparts (Kotanbetsu sections) show good coherence between radiometric chronometers on the various Upper Cretaceous stage boundaries. These additional ages together with our isotope ages from the different sections around the Hokkaido basin are well linked by the various faunal assemblages and C-isotope curves. The combined radio isotope ages contribute to previous attempts (such as those focused in the Western Interior Basin) supporting the synchronicity of events such as global oceanic anoxic events. Finally, the ages obtained here also compliment the previous C-isotope and planktic foraminifera records allowing for a more precise climatic history of the Northwest Pacific during the Cretaceous. The research within the GTSnext project is funded by the European Community's Seventh

  4. Stratigraphy of mid-Cretaceous formations at drilling sites in Weston and Johnson counties, northeastern Wyoming

    USGS Publications Warehouse

    Mereweather, E.A.

    1980-01-01

    The sedimentary rocks of early Late Cretaceous age in Weston County, Wyo., on the east flank of the Powder River Basin, are assigned, in ascending order, to the Belle Fourche Shale, Greenhorn Formation, and Carlile Shale. In Johnson County, on the west flank of the basin, the lower Upper Cretaceous strata are included in the Frontier Formation and the overlying Cody Shale. The Frontier Formation and some of the laterally equivalent strata in the Rocky Mountain region contain major resources of oil and gas. These rocks also include commercial deposits of bentonite. Outcrop sections, borehole logs, and core studies of the lower Upper Cretaceous rocks near Osage, in Weston County, and Kaycee, in Johnson County, supplement comparative studies of the fossils in the formations. Fossils of Cenomanian, Turonian, and Coniacian Age are abundant at these localities and form sequences of species which can be used for the zonation and correlation of strata throughout the region. The Belle Fourche Shale near Osage is about 115 m (meters) thick and consists mainly of noncalcareous shale, which was deposited in offshore-marine environments during Cenomanian time. These strata are overlain by calcareous shale and limestone of the Greenhorn Formation. In this area, the Greenhorn is about 85 m thick and accumulated in offshore, open-marine environments during the Cenomanian and early Turonian. The Carlile Shale overlies the Greenhorn and is composed of, from oldest to youngest, the Pool Creek Member, Turner Sandy Member, and Sage Breaks Member. In boreholes, the Pool Creek Member is about 23 m thick and consists largely of shale. The member was deposited in offshoremarine environments in Turonian time. These rocks are disconformably overlain by the Turner Sandy Member, a sequence about 50 m thick of interstratified shale, siltstone, and sandstone. The Turner accumulated during the Turonian in several shallow-marine environments. Conformably overlying the Turner is the slightly

  5. Jonah field, sublette county, Wyoming: Gas production from overpressured Upper Cretaceous Lance sandstones of the Green River basin

    USGS Publications Warehouse

    Montgomery, S.L.; Robinson, J.W.

    1997-01-01

    Jonah field, located in the northwestern Green River basin, Wyoming, produces gas from overpressured fluvial channel sandstones of the Upper Cretaceous Lance Formation. Reservoirs exist in isolated and amalgamated channel facies 10-100 ft (3-30 m) thick and 150-4000 ft (45-1210 m) wide, deposited by meandering and braided streams. Compositional and paleocurrent studies indicate these streams flowed eastward and had their source area in highlands associated with the Wyoming-Idaho thrust belt to the west. Productive sandstones at Jonah have been divided into five pay intervals, only one of which (Jonah interval) displays continuity across most of the field. Porosities in clean, productive sandstones range from 8 to 12%, with core permeabilities of .01-0.9 md (millidarcys) and in-situ permeabilities as low as 3-20 ??d (microdarcys), as determined by pressure buildup analyses. Structurally, the field is bounded by faults that have partly controlled the level of overpressuring. This level is 2500 ft (758 m) higher at Jonah field than in surrounding parts of the basin, extending to the top part of the Lance Formation. The field was discovered in 1975, but only in the 1990s did the area become fully commercial, due to improvements in fracture stimulation techniques. Recent advances in this area have further increased recoverable reserves and serve as a potential example for future development of tight gas sands elsewhere in the Rocky Mountain region.

  6. Sedimentology and sequence stratigraphy of the Cretaceous Nanushuk, Seabee, and Tuluvak formations exposed on Umiat Mountain, north-central Alaska

    USGS Publications Warehouse

    Houseknecht, David W.; Schenk, Christopher J.

    2005-01-01

    Upper Cretaceous strata of the upper part of the Nanushuk Formation, the Seabee Formation, and the lower part of the Tuluvak Formation are exposed along the Colville River on the east flank of Umiat Mountain in north-central Alaska. The Ninuluk sandstone, which is the uppermost unit of the Nanushuk Formation, displays a vertical succession of facies indicative of deposition in an upward-deepening estuarine through shoreface setting. A marine-flooding surface lies between the Ninuluk sandstone and organic-rich shale of the basal part of the Seabee Formation. The Ninuluk sandstone and the lower part of the Seabee Formation are interpreted as components of a transgressive-systems tract. The lowest, well-exposed strata in the Seabee Formation are a succession of shoreface sandstone beds in the middle of the formation. Integration of outcrop information and the Umiat No. 11 well log suggests that this sandstone succession rests on a sequence boundary and is capped by a marine-flooding surface. The sandstone succession is interpreted as a lowstand-systems tract. The upper part of the Seabee Formation includes a thick interval of organic-rich shale deposited in a dysaerobic offshore environment, and the gradational Seabee-Tuluvak contact is a coarsening-upward shale-to-sandstone succession deposited in a prodelta/delta-front environment. The observation that the upper part of the Seabee Formation correlates with seismic clinoforms suggests that dysaerobic conditions extended well up onto the prodelta slope during intervals of transgression and highstand. Correlation of the Umiat Mountain outcrop section with well logs and seismic data suggests that sequence boundaries and lowstand shoreface deposits may be common in the Seabee Formation and that wave action may have been important in transporting sand to the paleoshelf margin. These conclusions may contribute to an enhanced understanding of sand distribution in prospective lowstand turbidite deposits in the subsurface of

  7. Assessment of gas resources in low-permeability sandstones of Upper Cretaceous Mesaverde Group, Piceance Basin, Colorado

    SciTech Connect

    Johnson, R.C.; Crovelli, R.A.; Spencer, C.W.; Mast, R.F.

    1988-01-01

    A modified volumetric approach is used to estimate gas resources in the low-permeability sandstones of the Upper Cretaceous Mesaverde Group in the Piceance basin of western Colorado. The Mesaverde Group was divided into three plays based on stratigraphy - the Williams Fork Formation, the Iles Formation, and the Rollins Sandstone Member (Mesaverde Formation) or Trout Creek Sandstone Member (Iles Formation). Each of these plays was subdivided into a deep-gas play and a shallower gas-water transition play. Variations in thermal maturity were used to define the boundaries of the plays. The aggregated mean in-place gas for all six plays is 419.55 tcf. The mean in-place resource numbers were run through probability programs, which assign estimates of the gas potential at the 95%, 75%, 50%, 25%, and 5% probability levels both for individual plays and for the aggregate of all six plays. Assuming a 75% degree of dependency between the plays, there is a 95% chance of at least 274.45 tcf of total inplace gas, a 50% chance of 407.60 tcf, and a 5% chance of 605.33 tcf. Next, six different recovery factors were used. The first three assume current technology and a gas price of $5/mcf, and the second three assume future advanced technology without a gas price specified. The most likely estimated recoverable gas figures for the six plays at the 95%, 50%, and 5% probability levels using current technology are 8.75, 13.03, and 19.41 tcf, and using future advanced technology are 44.23, 65.97, and 98.39 tcf.

  8. Upper Cretaceous-Paleocene extensional phase in the Golfo San Jorge basin (Argentina): Growth-fault model, paleoseismicity and paleostress analysis

    NASA Astrophysics Data System (ADS)

    Foix, Nicolás; Paredes, José Matildo; Giacosa, Raúl Eduardo

    2012-02-01

    A total of 170 synsedimentary normal faults preserved in the marine Salamanca Formation (Early Paleocene of the Golfo San Jorge basin) were described from exposures of the Northern Flank of the basin. The result of the paleostress analysis of those normal faults indicates an NE-SW (49°) extensional direction during Early Paleocene times. Synsedimentary normal faults and seismites in the unit demonstrate the occurrence of an extensional tectonic event coeval with the deposition of the Salamanca Formation. Available 3D seismic surveys of the subsurface of the basin allowed recognizing asymmetric, fault-bounded Upper Cretaceous-Paleocene depocentres, identifying at least two main tectonic pulses in this extensional phase. The mapping of normal faults from seismic attributes (e.g. time slices) is WNW-ESE (278°-98°), a trend that apart significantly from outcrop results. The major faults in the subsurface that affect the Early Paleocene succession are the result of the extensional reactivation of Lower Cretaceous normal faults, which are mainly related to pre-existing structures in the basement of the basin. The D/L ratio of normal faults in the subsurface give smaller values than those based on theoretical relationships, being considered as sub-displaced normal faults. These low D-L values imply that the length of the major Paleocene faults was reached earlier by inheritance of previous faults. In addition, the subsurface lengths of faults allowed estimating paleoearthquake magnitudes greater to M ≈ 5 from empirical relations, matching with previous results obtained from the analysis of soft-sediment deformational structures preserved in the Salamanca Formation. This study displays at several scales the nature, origin and tectonic products of the Upper Cretaceous-Paleocene extensional phase in the Golfo San Jorge basin.

  9. Geologic models and evaluation of undiscovered conventional and continuous oil and gas resources: Upper Cretaceous Austin Chalk

    USGS Publications Warehouse

    Pearson, Krystal

    2012-01-01

    The Upper Cretaceous Austin Chalk forms a low-permeability, onshore Gulf of Mexico reservoir that produces oil and gas from major fractures oriented parallel to the underlying Lower Cretaceous shelf edge. Horizontal drilling links these fracture systems to create an interconnected network that drains the reservoir. Field and well locations along the production trend are controlled by fracture networks. Highly fractured chalk is present along both regional and local fault zones. Fractures are also genetically linked to movement of the underlying Jurassic Louann Salt with tensile fractures forming downdip of salt-related structures creating the most effective reservoirs. Undiscovered accumulations should also be associated with structure-controlled fracture systems because much of the Austin that overlies the Lower Cretaceous shelf edge remains unexplored. The Upper Cretaceous Eagle Ford Shale is the primary source rock for Austin Chalk hydrocarbons. This transgressive marine shale varies in thickness and lithology across the study area and contains both oil- and gas-prone kerogen. The Eagle Ford began generating oil and gas in the early Miocene, and vertical migration through fractures was sufficient to charge the Austin reservoirs.

  10. Model of the Arctic evolution since the Cretaceous to present, based on upper mantle convection linked with Pacific lithosphere subduction

    NASA Astrophysics Data System (ADS)

    Lobkovsky, Leopold

    2015-04-01

    The present paper comprises a model of Arctic basin evolution since early-mid Cretaceous to present. The model is based on the mechanism of upper mantle substance circulation beneath the Arctic lithosphere linked with Pacific lithosphere subduction. Seismic tomography data obtained for the Pacific-Eurasia-Arctic joint area indicate that Pacific lithosphere slab sinking to the mantle in subduction zone transforms into the horizontal layer upon reaching the upper mantle foot, this layer extending for two or more thousands km beneath the Eurasian continent. This pattern of seismic tomography indicates the presence of a horizontal convective cell where a flow of substance moving along the upper mantle foot from a subduction zone into the continent is compensated by a return flow moving along the lithosphere foot towards the subduction zone. The return mantle flow makes continental lithosphere extension, giving rise to processes of rifting, magmatism and spreading. The convective cell being continuously supplied with new substance which is transported through the subduction zone it is sure to expand horizontally. The above cell expansion occurs first, due to ocean ward movement of subduction zone (roll back) and secondly, due to the cell front propagation into the continent. The given model allows to understand main features for the Arctic evolution since early-mid Cretaceous to present. Numerous seismic profiling data obtained for shelf and deep water sedimentary basins in the Arctic Ocean as well as on land geological investigation reveal that since Aptian up to present the Arctic region has been characterized by sublatitudinal lithosphere extension. This extension is explained by the effect the return mantle flow related to the subduction of the Northern part of the Pacific plate acts on the Arctic lithosphere foot. The model shows the phenomenon of Arctic plume to be caused by the convective cell uprising flow. In fact lower horizontal flow of convective cell moving

  11. Interpretation of Late Cretaceous Volcanic Mounds and Surrounding Gulfian Series Formations Using 3D Seismic Data in Zavala County, Texas

    NASA Astrophysics Data System (ADS)

    Bennett, Laura Claire

    The Late Cretaceous Gulfian series is a prominent and important series across the State of Texas that has been extensively studied since the nineteenth century. It is composed of series of southeast-dipping shelf carbonates and clastics deposited on the northwest margin of the Gulf of Mexico Basin. In south Texas, the Gulfian series was deposited in the Rio Grande Embayment and Maverick Basin and is comprised of the Eagle Ford Group, Austin Group, Anacacho Limestone, San Miguel Formation, Olmos Formation, and Escondido Formation that crop out and continue basinward in the subsurface. Late Cretaceous volcanism formed volcanic mounds composed of altered palagonite tuff that are clustered into two fields, including the Uvalde Field centered in Zavala County. Using the Pedernales 3D seismic survey, located in east-central Zavala County, several volcanic mounds were identified and mapped without the use of well log data by identifying structures and characteristics associated with the volcanic mounds. Isolating these mounds through mapping enabled the mapping of the tops surrounding Gulfian formations, Lower Eagle Ford, Upper Eagle Ford, Austin, Anacacho, and San Miguel, for which time-structure, amplitude, similarity/coherency attribute, and isochron maps were generated. By using 3D seismic data, the volcanic mounds and their relation to surrounding rocks can be better interpreted.

  12. A psittacosaurid-like basal neoceratopsian from the Upper Cretaceous of central China and its implications for basal ceratopsian evolution

    PubMed Central

    Zheng, Wenjie; Jin, Xingsheng; Xu, Xing

    2015-01-01

    Psittacosauridae (parrot-beaked dinosaurs) represents the first major radiation of ceratopsians (horned dinosaurs). However, psittacosaurids are divergent from the general morphology found in other ceratopsians, and this has resulted in their uncertain systematic position among ceratopsians. Here we describe a new basal neoceratopsian dinosaur, Mosaiceratops azumai gen. et sp. nov. based on a partial semi-articulated skeleton recovered from the Upper Cretaceous Xiaguan Formation of Neixiang County, Henan Province, China. Although our phylogenetic analysis supports this taxon as the most basal neoceratopsian, Mosaiceratops exhibits many features previously considered unique to the Psittacosauridae among the basal Ceratopsia. These include a relatively highly positioned external naris, a proportionally large premaxilla, the nasal extending ventral to the external naris, slender postorbital and temporal bars, a large notch between the basal tubera, and the edentulous premaxilla. Thus, the discovery of Mosaiceratops reduces the morphological disparity between the Psittacosauridae and other basal ceratopsians. Character optimization suggests that basal neoceratopsians have re-evolved premaxillary teeth; a major reversal previously unknown in any dinosaur clade. The new specimen also highlights the mosaic nature of evolution among early ceratopsians and supports the phylogenetic hypothesis that the Psittacosauridae is a relatively derived clade, rather than the most basal group of the Ceratopsia. PMID:26388024

  13. Tectonic significance of lithicwacke-polymictic conglomerate petrofacies association within Upper Cretaceous torchlight sandstone, Big Horn basin, Wyoming

    SciTech Connect

    Khandaker, N.I.; Vondra, C.F.

    1987-05-01

    The Torchlight Sandstone belonging to the Upper Cretaceous Frontier Formation in the Big Horn basin, Wyoming, shows a distinctive lithicwacke-polymictic conglomerate is composed of granule-cobble-sized clasts of quartzite, chert, andesite, and argillite, and phyllite. The survival of phyllite, argillite, and neovolcanic andesite clasts indicate that the detritus underwent very little subaerial transport before it was deposited along the proximal margin of the foreland basin. A petrologically heterogeneous upland source of high to moderate relief is indicated by the clast size and composition. Hydrodynamic structures, in conjunction with textural attributes, and compositional data indicate that detritus moved southeast from its source terrane and was deposited by a high-energy distributary complex. The lithicwacke petrofacies is dominated by higher chert and quartz content with a subordinate amount of labile components including paleovolcanic clasts and fine-grained matrix. The development of phyllosilicate matrix around quartz and chert grains preserved the primary porosity and permeability of the sandstone. Absence of any noticeable quartz overgrowth apparently contributed to the preservation of good reservoir quality in this petrofacies. Considering its (Torchlight Sandstone) close proximity to the thrust belt and to the locus of andesite volcanism in the northwest and west, it is suggested that the extrabasinal detritus within the foreland basin can provide significant clues as to the timing of the thrust events and volcanicity in the adjacent region. New perspectives for hydrocarbon exploration and regional correlation may be gained by employing this petrofacies association.

  14. A Short-Armed Troodontid Dinosaur from the Upper Cretaceous of Inner Mongolia and Its Implications for Troodontid Evolution

    PubMed Central

    Xu, Xing; Tan, Qingwei; Sullivan, Corwin; Han, Fenglu; Xiao, Dong

    2011-01-01

    Background The Troodontidae represents one of the most bird-like theropod groups and plays an important role in our understanding of avian origins. Although troodontids have been known for over 150 years, few known derived troodontid specimens preserve significant portions of both the forelimb and the hindlimb. Methodology/Principal Findings Here, we report a new troodontid taxon, Linhevenator tani gen. et sp. nov., based on a partial, semi-articulated skeleton recovered from the Upper Cretaceous Wulansuhai Formation of Wulatehouqi, Inner Mongolia, China. L. tani has an unusual combination of primitive and derived character states, though our phylogenetic analysis places it in a derived clade within the Troodontidae. As a derived taxon, L. tani has a dromaeosaurid-like pedal digit II, and this species also possesses a humerus that is proportionally much shorter and more robust than those of most other troodontids. Conclusion/Significance The combination of features present in Linhevenator indicates a complex pattern of character evolution within the Troodontidae. In particular, the discovery of Linhevenator suggests that derived troodontids have independently evolved a highly specialized pedal digit II and have significantly shortened the forelimb over the course of their evolution. PMID:21915256

  15. A psittacosaurid-like basal neoceratopsian from the Upper Cretaceous of central China and its implications for basal ceratopsian evolution.

    PubMed

    Zheng, Wenjie; Jin, Xingsheng; Xu, Xing

    2015-01-01

    Psittacosauridae (parrot-beaked dinosaurs) represents the first major radiation of ceratopsians (horned dinosaurs). However, psittacosaurids are divergent from the general morphology found in other ceratopsians, and this has resulted in their uncertain systematic position among ceratopsians. Here we describe a new basal neoceratopsian dinosaur, Mosaiceratops azumai gen. et sp. nov. based on a partial semi-articulated skeleton recovered from the Upper Cretaceous Xiaguan Formation of Neixiang County, Henan Province, China. Although our phylogenetic analysis supports this taxon as the most basal neoceratopsian, Mosaiceratops exhibits many features previously considered unique to the Psittacosauridae among the basal Ceratopsia. These include a relatively highly positioned external naris, a proportionally large premaxilla, the nasal extending ventral to the external naris, slender postorbital and temporal bars, a large notch between the basal tubera, and the edentulous premaxilla. Thus, the discovery of Mosaiceratops reduces the morphological disparity between the Psittacosauridae and other basal ceratopsians. Character optimization suggests that basal neoceratopsians have re-evolved premaxillary teeth; a major reversal previously unknown in any dinosaur clade. The new specimen also highlights the mosaic nature of evolution among early ceratopsians and supports the phylogenetic hypothesis that the Psittacosauridae is a relatively derived clade, rather than the most basal group of the Ceratopsia. PMID:26388024

  16. Upper Cretaceous Vernal delta of Utah-depositional or paleotectonic feature

    SciTech Connect

    Ryer, T.A.; Lovekin, J.R.

    1985-05-01

    A conspicuous seaward bulge of the middle to late Turonian shoreline of the Cretaceous seaway in northeastern Utah and southwestern Wyoming has been identified by previous authors as the Vernal delta. Strata of the Frontier Formation and the Ferron Sandstone Member of the Mancos Shale that form the Vernal delta consist largely of fluviodeltaic facies. The delta, however, is not recognizable as a locus of Turonian sedimentation; there is no isopach thick associated with it. The Vernal data is a large feature, encompassing an area of at least 6250 mi/sup 2/ (16,187 km/sup 2/). A comparison between the depositional setting and paleogeography of northeastern Utah during the Late Cretaceous and a present-day area on the east flank of the Andes in Colombia indicates strong similarities. Further comparison suggests that feature the size of the Vernal delta could not have been produced by a single river. The Vernal delta overlies the ancestral Uinta Mountain uplift, an area where Cenomanian marine shales were entirely removed by what appears to have been submarine erosion during early Turonian time. When the shoreline prograded eastward across this area during middle Uronian time, the sediment load caused the area to subside, but at a rate slower than rates of subsidence to the north and south. This differential subsidence is the cause of the shoreline bulge. Although it includes deltaic facies, the Vernal delta is not a delta per se, but a feature produced as the result of interaction between sedimentation and gentle tectonic movement of the ancestral Uinta Mountain uplift.

  17. Paleotemperatures and paleodepths of the Upper Cretaceous rocks in El Qusaima, Northeastern Sinai, Egypt

    NASA Astrophysics Data System (ADS)

    Orabi, O. H.; Zahran, E.

    2014-03-01

    The planktonic foraminiferal morphogroups and planktonic quantitative analysis as well as the lithological variations across the Coniacian to Maastrichtian sediments of El Qusaima section (Northeastern Sinai, Egypt) are studied in detail in order to detect the prevailing paleoecological conditions along these sediments. At the studied area of El Qusaima section there is a gradual cooling started at the base of Globotruncana elevata Zone (early-middle Campanian) of the lower part of the Markha Member and continued till Globotruncana aegyptiaca Zone (Late Campanian) of the upper part of the Markha Member. This trend corresponds to the onset of a global cooling that began at about 73 Ma (Late Campanian) and ended the Cretaceous greenhouse climate mode. At El Qusaima section, a gradual warming started at the base of Pseudogumbelina palpebra Zone (Late Maastrichtian) and continued till Plummerita hantkeninoides Zone (latest Maastrichtian) due to the high abundance of Plummerita hantkeninoides and Plummeritareicheli, which have been flourishing in warm waters. So this warming near the end of the Maastrichtian is a global event as shown by many authors.

  18. The upper cretaceous snake Dinilysia patagonica Smith-Woodward, 1901, and the crista circumfenestralis of snakes.

    PubMed

    Palci, Alessandro; Caldwell, Michael W

    2014-10-01

    Studies on the phylogenetic relationships of snakes and lizards are plagued by problematic characterizations of anatomy that are then used to define characters and states in taxon-character matrices. State assignments and character descriptions must be clear characterizations of observable anatomy and topological relationships if homologies are to be hypothesized. A supposed homology among snakes, not observed in lizards, is the presence of a crista circumfenestralis (CCF), a system of bony crests surrounding the fenestra ovalis and lateral aperture of the recessus scalae tympani. We note that there are some fossil and extant snakes that lack a CCF, and some extant lizards that possess a morphological equivalent. The phylogenetically important upper Cretaceous fossil snake Dinilysia patagonica has been interpreted by different authors as either having or lacking a CCF. These conflicting results for Dinilysia were tested by re-examining the morphology of the otic region in a large sample of snakes and lizards. An unambiguous criterion arising from the test of topology is used to define the presence of a CCF: the enclosure of the ventral margin of the juxtastapedial recess by flanges of the otoccipital (crista tuberalis and crista interfenestralis) that extend forward to contact the posterior margin of the prootic. According to this criterion D. patagonica does not possess a CCF, therefore, this anatomical feature must have arisen later during the evolution of snakes.

  19. Seismic detection of Upper Cretaceous stratigraphic oil traps in the Powder River Basin, Wyoming

    SciTech Connect

    Fuller, B.N.

    1988-01-01

    Upper Cretaceous sand ridges that serve as stratigraphic oil traps in the Powder River Basin, Wyoming have been difficult to find by standard seismic techniques, largely because the sands average less than 10 m in thickness. A direct detection approach to seismic exploration for the sands was taken by using amplitude-with-offset and pattern recognition analyses of seismic reflection data. The seismic data presented were recorded at Hartzog Draw oil field where oil is produced from a sand ridge complex that is enveloped in marine shells. Known reservoir sands a thin a 5 m were detected by the amplitude-with-offset method. The amplitude-with-offset variation was caused by a large difference in Poisson's ratio between the reservoir sands and the enveloping marine shale; reflection coefficients are known to vary significantly with angle of incidence when a large change in Poisson's ratio occurs upon crossing a reflecting boundary. The pattern recognition analysis was carried out to test the effectiveness of the pattern recognition method in defining the edges of oil fields and in recognizing prospective new hydrocarbon reserves. The pattern recognition software performed well in precisely identifying the western edge of Hartzog Draw field and in recognizing a large part of the eastern side of the field. The methods discussed have promise for seismic exploration and exploitation around the world.

  20. New predatory cockroaches (Insecta: Blattaria: Manipulatoridae fam.n.) from the Upper Cretaceous Myanmar amber

    NASA Astrophysics Data System (ADS)

    Vršanský, Peter; Bechly, Günter

    2015-04-01

    We describe a new extinct lineage Manipulatoridae (new family) of cockroaches from the Upper Cretaceous (Cenomanian) amber of Myanmar. Manipulator modificaputis gen. et sp. n. is a morphologically unique extinct cockroach that represents the first (of a total of 29 known worldwide) cockroach family reported exclusively from the Myanmar amber. This family represents an early side branch of the stem group of Mantodea (most probably a sister group of Eadiidae within Blattaria/Corydioidea) because it has some synapomorphies with the Mantodea (including the stem group and Eadiidae). This family also retains symplesiomorphies that exclude a position in the crown group, and furthermore has unique autapomorphies that exclude a position as a direct ancestor of Mantodea. The unique adaptations such as strongly elongated extremities and freely movable head on a long neck suggest that these animals were pursuit predators. Five additional specimens (including two immatures) reported from the Myanmar amber suggest that this group was relatively rare but belonged to the indigenous and autochthonous inhabitants of the ancient amber forest of the Myanmar region.

  1. Influence of paleoenvironmental factors on preservation of organic matter in Middle Cretaceous Greenhorn formation, Pueblo Colorado

    SciTech Connect

    Pratt, L.M.

    1984-09-01

    Sedimentological and geochemical studies of the Upper Cretaceous Hartland Shale and overlying Bridge Creek Limestone Members of the Greenhorn Formation reveal close associations between abundance of current-induced sedimentary structures, extent of bioturbation, and type of preserved organic matter. Abundant hydrogen-rich organic matter (4-5 wt. %) and low sulfur to organic carbon ratios are characteristic of the laminated facies, which lack current-induced sedimentary structures. Sparse hydrogen-poor organic matter (0.1-0.5 wt. %) and relatively high sulfur to organic carbon ratios are characteristic of the bioturbated facies, which contain numerous sedimentary structures indicative of current. The concentration of oxygen in the benthic environment and the degree of bioturbation of the sediment apparently were determined principally by the rate that oxygen was supplied advectively (by currents) rather than by the rate of oxygen consumption (by decomposition). It is proposed that episodes of high river discharge lead to density stratification of the water column and in turn to quiescent oxygen-depleted bottom water and high preservation of organic matter, thus accounting for the intermittent widespread deposition of organic-rich strata during maximum transgression and depth of the Greenhorn sea. The lateral association of voluminous deltaic deposits with deep-water black shales in other elongate or restricted marine basins may have causes similar to those envisioned for the Hartland Shale and Bridge Creek Limestone Members.

  2. Regional disconformities in Turonian and Coniacian (Upper Cretaceous) strata in Colorado, Wyoming, and adjoining states - Biochronological evidence

    USGS Publications Warehouse

    Merewether, E.A.; Cobban, W.A.; Obradovich, J.D.

    2007-01-01

    Siliciclastic and calcareous sedimentary rocks of early Late Cretaceous age in the Western Interior of the United States have been assigned to, in ascending order, the Graneros Shale, Greenhorn Formation, Carlile Shale, Niobrara Formation, and their lateral equivalents (including members of the Frontier Formation and overlying formations). This sequence of formations was deposited intermittently within and near an epicontinental seaway during the Cenomanian, Turonian, and Coniacian stages of the Cretaceous. It encloses three conspicuous and widespread disconformities that reflect regional marine regressions and transgressions as well as moderate tectonism. The disconformities and associated lacunae occupy three large areas within Wyoming, Colorado, and adjoining states. In parts of that region, as in northwestern Wyoming, a lacuna can represent more than one period of erosion and more than a single disconformity. Evidence for these disconformities was obtained from about 175 collections of molluscan fossils and from sedimentological studies of outcrops and borehole logs, supplemented by previously published data.

  3. Palynological age determination for Dorcheat and Hosston Formations - Jurassic-Cretaceous boundary in northern Louisiana

    SciTech Connect

    Rogers, R.

    1987-09-01

    Forty-four core samples from three wells drilled into the Dorcheat and Hosston formations in northern Louisiana were examined for fossil palynomorphs. These samples were obtained from the four beds of the Dorcheat formation, and from the lower two beds of the Hosston Formation. A diverse terrestrial and marine palynoflora containing stratigraphically significant species indicates that the cored section of strata spans the Jurassic-Cretaceous boundary.

  4. Cobbania corrugata gen. et comb. nov. (Araceae): a floating aquatic monocot from the Upper Cretaceous of western North America.

    PubMed

    Stockey, Ruth A; Rothwell, Gar W; Johnson, Kirk R

    2007-04-01

    The fossil record of aquatic flowering plants broadens our understanding of their former diversity and origins from terrestrial ancestors. This paper describes a floating aquatic monocot from 71 whole plants and several isolated leaf fragments from Upper Cretaceous oxbow lake sediments in the Dinosaur Park Formation, Alberta, Canada. The new material is represented by rosettes of leaves and roots attached to short stems that are interconnected by stolons and corresponds to the fossil aroid originally described as Pistia corrugata Lesquereux. Up to six plants have been found interconnected on a single slab suggesting that these plants grew in extensive floating mats covering lakes and calm stretches of rivers. Stems have up to six leaves and large numbers of branched aquatic roots. The leaf is trumpet-shaped with an elongate clasping petiole, large aerenchymatous base, and a nearly circular blade rim. Leaf bases are often filled with sediment giving the leaf the appearance of having a basal pouch. Petioles have 6-9 veins that divide into an upper and lower set, and veins converge at an apical notch. A submarginal collective vein and at least two marginal veins with branching veins form the leaf rim. A series of dichotomizing and anastomosing veins characterize the adaxial leaf surface. Tertiary and quaternary veins form polygonal areolae. Leaf surfaces are covered in trichomes that, like those in Pistia stratiotes, probably aided in buoyancy. A reconstruction of the plant is presented. Based on unique leaf morphology, these fossil plants are clearly not assignable to the genus Pistia and are described as Cobbania corrugata (Lesquereux) Stockey, Rothwell et Johnson gen. et comb. nov. Recent systematic analyses using molecular characters resolve two separate origins of floating aquatic aroids included in the duckweeds and the genus Pistia. This new fossil genus increases our understanding of colonization of aquatic habitats by revealing a third possible origin of the

  5. Heavy mineral delineation of the Cretaceous, Paleocene, and Eocene stratigraphic sections at the Savannah River Site, Upper Coastal Plain of South Carolina

    SciTech Connect

    Cathcart, E.M. . Dept. of Geology); Sargent, K.A. . Dept. of Geology)

    1994-03-01

    The Upper Atlantic Coastal Plain of South Carolina consists of a fluvial-deltaic and shallow marine complex of unconsolidated sediments overlying the crystalline basement rocks of the North American continent. Because of the lateral and vertical variability of these sediments, stratigraphic boundaries have been difficult to distinguish. Portions of the Cretaceous, Paleocene, and eocene stratigraphic sections from cores recovered during the construction of two monitoring wells at the Savannah River Site were studied to determine if heavy mineral suites could be utilized to distinguish boundaries. The stratigraphic sections include: the Late Cretaceous Middendorf, Black Creek, and Steel Creek Formations, the Paleocene Snapp Formation, the late Paleocene-Early Eocene Fourmile Branch Formation, and the Early Eocene Congaree formation. In previous studies composite samples were taken over 2.5 ft. intervals along the cores and processed using a heavy liquid for heavy mineral recovery. During this study, heavy mineral distributions were determined by binocular microscope and the mineral identifications confirmed by x-ray diffraction analysis of hand-picked samples. The heavy mineral concentration data and grain size data were then compared to the stratigraphic boundary positions determined by other workers using more classical methods. These comparisons were used to establish the utility of this method for delineating the stratigraphic boundaries in the area of study.

  6. Sauropod and theropod dinosaur tracks from the Upper Cretaceous of Mendoza (Argentina): Trackmakers and anatomical evidences

    NASA Astrophysics Data System (ADS)

    González Riga, Bernardo Javier; Ortiz David, Leonardo Daniel; Tomaselli, María Belén; dos Anjos Candeiro, Carlos Roberto; Coria, Juan Pedro; Prámparo, Mercedes

    2015-08-01

    New findings of dinosaur ichnites from Agua del Choique section (Mendoza Province, Argentina) provides ichnological and anatomical information about the Cretaceous sauropods and theropods. Around 330 tracks distributed in six footprint levels were identified in this area, one of most important of South America. Two ichnocenoses are located in different paleoenvironmental contexts. In the Anacleto Formation (early Campanian) around 20 titanosaurian tracks were found in floodplain and ephemeral channel deposits. Herein, one pes track shows three claw impressions and this is congruent to two new titanosaur specimens recently discovered in Mendoza Province that have articulated and complete pedes. In this context, for the first time to titanosaurs, ichnological evidences are supported by skeletal elements. In the Loncoche Formation (late Campanian-early Maastrichtian) titanosaurian tracks of Titanopodus mendozensis are abundant (around 310 tracks) and were produced by titanosaurs that walked in a very wet substrate of tidally dominated deltas related with the first Atlantic transgression for northern Patagonia. In this facies association, three different trydactl tracks indicate the presence of small theropods (1-2 m long), expanding the knowledge about the faunistic components that lived in these marine marginal environments.

  7. Correlation of the Cretaceous formations of Greenland and Alaska

    USGS Publications Warehouse

    Imlay, Ralph Willard; Reeside, John B.

    1953-01-01

    This is Number 10d of a series of correlation charts prepared for the Committee on Stratigraphy of the National Research Council. It has been sponsored by the U.S. Geological Survey and has required about seven months' time of both authors gathering and compiling data and evaluating fossil evidence. As the two regions dealt with in the chart are widely separated, the lists of references are also given separately. The annotations dealing with Greenland are based entirely on published information. The annotations dealing with Alaska are based on a re-examination of nearly all the Cretaceous fossils from Alaska are based on a re-examination of nearly all the Cretaceous fossils from Alaska in the collections of the Geological Survey. This has resulted in many concepts not hitherto published and in some concepts that are completely at variance with those that have been published. Naturally for large areas undergoing active exploration, such as Alaska, a correlation chart is out of date in many particulars as soon as published. Nevertheless it is valuable to the field man whose activities are confined to small areas but who must interpret much of his data in terms of surrounding areas that he has not seen. It is valuable to the student and to the general geologist because it organizes scattered information in a manner that can be applied in their field problems, makes quite unnecessary the memorization of stratigraphic correlations are based on observation and reasoning and not on a vast memory. It is probably of greatest value to the specialist who makes the chart because he discovers what areas and problems are most in need of research and can thereby direct his efforts and those of his associates in a manner that will yield the greatest results.

  8. An Unusual New Theropod with a Didactyl Manus from the Upper Cretaceous of Patagonia, Argentina

    PubMed Central

    Apesteguía, Sebastián; Smith, Nathan D.; Juárez Valieri, Rubén; Makovicky, Peter J.

    2016-01-01

    Background Late Cretaceous terrestrial strata of the Neuquén Basin, northern Patagonia, Argentina have yielded a rich fauna of dinosaurs and other vertebrates. The diversity of saurischian dinosaurs is particularly high, especially in the late Cenomanian-early Turonian Huincul Formation, which has yielded specimens of rebacchisaurid and titanosaurian sauropods, and abelisaurid and carcharodontosaurid theropods. Continued sampling is adding to the known vertebrate diversity of this unit. Methodology/ Principal Findings A new, partially articulated mid-sized theropod was found in rocks from the Huincul Formation. It exhibits a unique combination of traits that distinguish it from other known theropods justifying erection of a new taxon, Gualicho shinyae gen. et sp. nov. Gualicho possesses a didactyl manus with the third digit reduced to a metacarpal splint reminiscent of tyrannosaurids, but both phylogenetic and multivariate analyses indicate that didactyly is convergent in these groups. Derived characters of the scapula, femur, and fibula supports the new theropod as the sister taxon of the nearly coeval African theropod Deltadromeus and as a neovenatorid carcharodontosaurian. A number of these features are independently present in ceratosaurs, and Gualicho exhibits an unusual mosaic of ceratosaurian and tetanuran synapomorphies distributed throughout the skeleton. Conclusions/ Significance Gualicho shinyae gen. et sp. nov. increases the known theropod diversity of the Huincul Formation and also represents the first likely neovenatorid from this unit. It is the most basal tetatanuran to exhibit common patterns of digit III reduction that evolved independently in a number of other tetanuran lineages. A close relationship with Deltadromaeus from the Kem Kem beds of Niger adds to the already considerable biogeographic similarity between the Huincul Formation and coeval rock units in North Africa. PMID:27410683

  9. Paleontologic and stratigraphic relations of phosphate beds in Upper Cretaceous rocks of the Cordillera Oriental, Colombia

    USGS Publications Warehouse

    Maughan, Edwin K.; Zambrano O., Francisco; Mojica G., Pedro; Abozaglo M., Jacob; Pachon P., Fernando; Duran R., Raul

    1979-01-01

    Phosphorite crops out in the Cordillera Oriental of the Colombian Andes in rocks of Late Cretaceous age as strata composed mostly of pelletal carbonate fluorapatite. One stratum of Santonian age near the base of the Galembo Member of the La Luna Formation crops out at many places in the Departments of Santander and Norte de Santander and may be of commercial grade. This stratum is more than one meter thick at several places near Lebrija and near Sardinata, farther south it is locally one meter thick or more near the base of the Guadalupe Formation in the Department of Boyaca. Other phosphorite beds are found at higher stratigraphic levels in the Galembo Member and the Guadalupe Formation, and at some places these may be commercial also. A stratigraphically lower phosphorite occurs below the Galembo Member in the Capacho Formation (Cenomanian age) in at least one area near the town of San Andres, Santander. A phosphorite or pebbly phosphate conglomerate derived from erosion of the Galembo Member forms the base of the Umir Shale and the equivalent Colon Shale at many places. Deposition of the apatite took place upon the continental shelf in marine water of presumed moderate depth between the Andean geosyncline and near-shore detrital deposits adjacent to the Guayana shield. Preliminary calculations indicate phosphorite reserves of approximately 315 million metric tons in 9 areas, determined from measurements of thickness, length of the outcrop, and by projecting the reserves to a maximum of 1,000 meters down the dip of the strata into the subsurface. Two mines were producing phosphate rock in 1969; one near Turmeque, Boyaca, and the other near Tesalia, Huila.

  10. A Gigantic Shark from the Lower Cretaceous Duck Creek Formation of Texas

    PubMed Central

    Frederickson, Joseph A.; Schaefer, Scott N.; Doucette-Frederickson, Janessa A.

    2015-01-01

    Three large lamniform shark vertebrae are described from the Lower Cretaceous of Texas. We interpret these fossils as belonging to a single individual with a calculated total body length of 6.3 m. This large individual compares favorably to another shark specimen from the roughly contemporaneous Kiowa Shale of Kansas. Neither specimen was recovered with associated teeth, making confident identification of the species impossible. However, both formations share a similar shark fauna, with Leptostyrax macrorhiza being the largest of the common lamniform sharks. Regardless of its actual identification, this new specimen provides further evidence that large-bodied lamniform sharks had evolved prior to the Late Cretaceous. PMID:26039066

  11. A gigantic shark from the lower cretaceous duck creek formation of Texas.

    PubMed

    Frederickson, Joseph A; Schaefer, Scott N; Doucette-Frederickson, Janessa A

    2015-01-01

    Three large lamniform shark vertebrae are described from the Lower Cretaceous of Texas. We interpret these fossils as belonging to a single individual with a calculated total body length of 6.3 m. This large individual compares favorably to another shark specimen from the roughly contemporaneous Kiowa Shale of Kansas. Neither specimen was recovered with associated teeth, making confident identification of the species impossible. However, both formations share a similar shark fauna, with Leptostyrax macrorhiza being the largest of the common lamniform sharks. Regardless of its actual identification, this new specimen provides further evidence that large-bodied lamniform sharks had evolved prior to the Late Cretaceous.

  12. A new dinosaur ichnotaxon from the Lower Cretaceous Patuxent Formation of Maryland and Virginia

    USGS Publications Warehouse

    Stanford, R.; Weems, R.E.; Lockley, M.G.

    2004-01-01

    In recent years, numerous dinosaur footprints have been discovered on bedding surfaces within the Lower Cretaceous Patuxent Formation of Maryland and Virginia. Among these, distinctive small tracks that display a combination of small manus with five digit impressions and a relatively much larger pes with four toe impressions evidently were made by animals belonging to the ornithischian family Hypsilophodontidae. These tracks differ from any ornithischian ichnotaxon previously described. We here name them Hypsiloichnus marylandicus and provide a description of their diagnostic characteristics. Although hypsilophodontid skeletal remains have not been found in the Patuxent, their skeletal remains are known from Lower Cretaceous strata of similar age in both western North America and Europe. Therefore, it is not surprising to find that an Early Cretaceous representative of this family also existed in eastern North America. ?? Taylor and Francis Ltd.

  13. Age estimation of the deposition of the cretaceous Upper Sandstones and a later remagnetization event, from Hirna area, SE Ethiopia

    NASA Astrophysics Data System (ADS)

    Atnafu, Balemwal; Kidane, Tesfaye

    2012-01-01

    Outcrops of the Cretaceous Upper sandstone formation some 375 km to the East of Addis Ababa on the motor Highway to Harar was paleomagnetically investigated. About seventy core samples were collected at various stratigraphic levels from 250-300 meters thick sedimentary formation. After standard sample preparations in the laboratory the resulting specimens were subjected to routine paleomagnetic demagnetization protocol. In the first steps of demagnetizations process the recent and viscous magnetizations were removed by heating until a temperature of level of 300 °C. Further demagnetization of the samples resulted in the isolation of the final magnetization with stable line segments that is directed towards the origin, which is interpreted as Characteristic Remanent Magnetization (ChRM). Rock - magnetic experiments have identified goethite (αFeOOH), hematite (αFe 2O 3), detritial hematite, and magnetite as the magnetic mineral phases carrying the remanence. The ChRM identified resulted in an average value of ( Ds = 0.5°, Is = -0.7°, α95 = 4.3°, N = 34) for the red sandstones while an average value of ( Ds = 335.8°, Is = -31.8°, α95 = 4.7°, N = 14) for the limestone intercalations. The former ChRM in the red sandstone is determined to be secondary while the latter ChRM is known to be primary. Comparison of these directional results and their pole equivalents with the African plate Apparent Polar Wander Path curve established by Besse and Courtillot (2003) give ages of between 115-130 Million years for the limestone intercalation and ages of 30 million years for red sandstone unit. These are interpreted respectively as estimates of the age of deposition and a later remagnetization respectively.

  14. Speciation and weathering of selenium in upper cretaceous chalk and shale from South Dakota and Wyoming, USA

    NASA Astrophysics Data System (ADS)

    Kulp, Thomas R.; Pratt, Lisa M.

    2004-09-01

    In geologic materials, petroleum, and the environment, selenium occurs in various oxidation states (VI, IV, 0, -II), mineralized forms, and organo-Se complexes. Each of these forms is characterized by specific chemical and biochemical properties that control the element's solubility, toxicity, and environmental behavior. The organic rich chalks and shales of the Upper Cretaceous Niobrara Formation and the Pierre Shale in South Dakota and Wyoming are bentoniferous stratigraphic intervals characterized by anomalously high concentrations of naturally occurring Se. Numerous environmental problems have been associated with Se derived from these geological units, including the development of seleniferous soils and vegetation that are toxic to livestock and the contamination of drinking water supplies by Se mobilized in groundwater. This study describes a sequential extraction protocol followed by speciation treatments and quantitative analysis by Hydride Generation-Atomic Absorption Spectroscopy. This protocol was utilized to investigate the geochemical forms and the oxidation states in which Se occurs in these geologic units. Organic Se and di-selenide minerals are the predominant forms of Se present in the chalks, shales, and bentonites, but distinctive variations in these forms were observed between different sample types. Chalks contain significantly greater proportions of Se in the form of di-selenide minerals (including Se associated with pyrite) than the shales where base-soluble, humic, organo-Se complexes are more prevalent. A comparison between unweathered samples collected from lithologic drill cores and weathered samples collected from outcrop suggest that the humic, organic-Se compounds in shale are formed during oxidative weathering and that Se oxidized by weathering is more likely to be retained by shale than by chalk. Selenium enrichment in bentonites is inferred to result from secondary processes including the adsorption of Se mobilized by groundwater

  15. Deposition and remaining productive capabilities of the Upper Cretaceous Eutaw sands of East-Central Mississippi

    SciTech Connect

    Greer, B.R.

    1995-10-01

    Nearing the close of the Cretaceous, there were several transgressions and regressions of the epicontinental seas. These rapid changes in sea level played a large part in the depositing and reworking of the Eutaw sands of East-Central Mississippi. The study area includes Jasper, Jones, Clarke and Wayne Counties. The Eutaw sands of this area are described as fine to very fine grained sand which are glauconitic, micaceous and sometimes fossiliferous. This indicates that the environment of deposition was in the neritic zone of the continental shelf. Its high porosities and permeabilities along with its prolific nature makes this formation one of the most sought after reservoirs of the state of Mississippi. All of the 18 Eutaw fields in the study area are closely reaching their economic limits for primary production. Four of these fields have undergone successful waterfloods which have greatly enhanced their ultimate recoveries. The remaining fields in the study area have the potential of yielding millions of barrels of oil from secondary and tertiary recovery methods.

  16. Upper Jurassic and Lower Cretaceous facies relationships in a passive margin basin, western North Atlantic

    SciTech Connect

    Prather, B.E.

    1988-02-01

    Correlation of facies from hydrocarbon-bearing continental and transitional marine sandstones to time-equivalent high-energy shelf-margin carbonates provide insight into hydrocarbon habitats of the Baltimore Canyon basin. These facies occur within a thick (> 10,000 ft) prograded wedge of shelf sediments in this passive margin basin. Wells drilled to test structural closures in shallow-water (< 600 ft) areas of Baltimore Canyon penetrate clastic facies which are time-equivalent to the downdip carbonate facies tested in deep-water wells. Numerous hydrocarbon shows, including a noncommercial gas and gas-condensate accumulation, occur with sandstone units that were deposited in prograding continental/fluvial and transitional marine environments located updip of the Oxfordian/Kimmeridgian carbonate shelf edge. The continental and transitional facies are overlain by a fine-grained deltaic complex which forms a regionally extensive top seal unit. The deltaic complex was deposited during aggradation of the Kimmeridgian through Berriasian shelf-margin carbonates penetrated by the deep-water wells. Deep-water wells (> 5000 ft) drilled off the continental shelf edge to test large structural closures along the downdip termination of the Upper Jurassic/Lower Cretaceous carbonate shelf edge encountered no significant hydrocarbon shows. Reservoir rocks in these wells consist of (1) oolite grainstone which was deposited within a shoal-water complex located at the Aptian shelf edge, and (2) coral-stromatoporoid grainstone and boundstone which formed an aggraded shelf-margin complex located at the Kimmeridgian through Berriasian shelf edge. Structural closures with reservoir and top seals are present in both updip and downdip trends. The absence of hydrocarbon shows in downdip carbonate reservoirs suggests a lack of source rocks available to charge objectives at the shelf margin.

  17. A New Leptoceratopsid (Ornithischia: Ceratopsia) from the Upper Cretaceous of Shandong, China and Its Implications for Neoceratopsian Evolution

    PubMed Central

    Xu, Xing; Wang, Kebai; Zhao, Xijin; Sullivan, Corwin; Chen, Shuqing

    2010-01-01

    Background The ceratopsians represent one of the last dinosaurian radiations. Traditionally the only universally accepted speciose clade within the group was the Ceratopsidae. However, recent discoveries and phylogenetic analyses have led to the recognition of a new speciose clade, the Leptoceratopsidae, which is predominantly known from the Upper Cretaceous of North America. Methodology/Principal Findings Here we report a new leptoceratopsid taxon, Zhuchengceratops inexpectus gen. et sp. nov., based on a partial, articulated skeleton recovered from the Upper Cretaceous Wangshi Group of Zhucheng, Shandong Province, China. Although Zhuchengceratops is significantly different from other known leptoceratopsids, it is recovered as a derived member of the group by our phylogenetic analysis. Furthermore, Zhuchengceratops exhibits several features previously unknown in leptoceratopsids but seen in ceratopsids and their close relatives, suggesting that the distribution of morphological features within ceratopsians is more complex than previously realized. Conclusion/Significance The discovery of Zhuchengceratops increases both the taxonomic diversity and the morphological disparity of the Leptoceratopsidae, providing further support for the hypothesis that this clade represents a successful radiation of horned dinosaurs in parallel with the Ceratopsidae in the Late Cretaceous. This documents a surprising case of the coexistence and radiation of two closely-related lineages with contrasting suites of jaw and dental features that probably reflect adaptation to different food resources. PMID:21079798

  18. Perinatal Specimens of Saurolophus angustirostris (Dinosauria: Hadrosauridae), from the Upper Cretaceous of Mongolia

    PubMed Central

    Dewaele, Leonard; Tsogtbaatar, Khishigjav; Barsbold, Rinchen; Garcia, Géraldine; Stein, Koen; Escuillié, François; Godefroit, Pascal

    2015-01-01

    Background The Late Cretaceous Nemegt Formation, Gobi Desert, Mongolia has already yielded abundant and complete skeletons of the hadrosaur Saurolophus angustirostris, from half-grown to adult individuals. Methodology/Principal Findings Herein we describe perinatal specimens of Saurolophus angustirostris, associated with fragmentary eggshell fragments. The skull length of these babies is around 5% that of the largest known S. angustirostris specimens, so these specimens document the earliest development stages of this giant hadrosaur and bridge a large hiatus in our knowledge of the ontogeny of S. angustirostris. Conclusions/Significance The studied specimens are likely part of a nest originally located on a riverbank point bar. The perinatal specimens were buried by sediment carried by the river current presumably during the wet summer season. Perinatal bones already displayed diagnostic characters for Saurolophus angustirostris, including premaxillae with a strongly reflected oral margin and upturned premaxillary body in lateral aspect. The absence of a supracranial crest and unfused halves of the cervical neural arches characterize the earliest stages in the ontogeny of S. angustirostris. The eggshell fragments associated with the perinatal individuals can be referred to the Spheroolithus oogenus and closely resemble those found in older formations (e.g. Barun Goyot Fm in Mongolia) or associated with more basal hadrosauroids (Bactrosaurus-Gilmoreosaurus in the Iren Dabasu Fm, Inner Mongolia, China). This observation suggests that the egg microstructure was similar in basal hadrosauroids and more advanced saurolophines. Competing Interests One of the authors (FE) is employed by the commercial organization Eldonia. Eldonia provided support in the form of a salary for FE, but did not have any additional role or influence in the study design, data collection and analysis, decision to publish, or preparation of the manuscript and it does not alter the authors

  19. Shocked cobbles in Lower Cretaceous Duwon Formation, South Korea: their classification and possible formation mechanisms

    NASA Astrophysics Data System (ADS)

    Lim, Hyoun Soo; Chae, Yong-Un; Kim, Kyung Soo; Kim, Cheng-Bin; Huh, Min

    2016-04-01

    Shocked cobbles are the cobbles having shock-induced deformation structures on the surfaces. The most distinctive macroscopic features are the subparallel fractures and the pervasive surface craters, with or without radial fractures. Until now, these shocked cobbles have been reported mainly in Europe, America, and Africa, but never been found or reported in Korea. Shocked cobbles have recently found in the Lower Cretaceous Duwon Formation in South Korea, which was the second report in Asia. The Duwon Formation consists mainly of conglomerates, gravelly sandstones and intercalated mudstone and shale layers. The shocked cobbles are commonly found in the lowermost clast-supported conglomerate layers, and they show various deformation features, such as pockmarked (circular or elliptical) cobbles, cratered (Hertzian or bowl-shaped) cobbles with or without radial fractures, cobbles showing subparallel fractures, and strongly squashed or heavily dissected cobbles. In general, these deformation structures are considered to have resulted from pressure dissolution by overburden, tectonic compression, and seismic or meteorite impacts. However, the exact formation mechanism is not clearly understood, and still in debate. The shocked cobbles found in the Duwon Formation have similar features to those of previously reported shocked cobbles, especially to Triassic Buntsandstein conglomerates in northeastern Spain. Based on the degree of deformation, the Duwon shocked cobbles can be divided into four types, which are (1) faint contact marks, (2) pitted marks without any fractures, (3) pitted marks with radial or sub-parallel fractures affected by pits, and (4) intensive fractures and heavily dissected fragments. The possible mechanisms for the Duwon shocked cobbles are thought to be crushing process by shear stress and pressure solution.

  20. Franciscan olistoliths in Upper Cretaceous conglomerate deposits, Western Transverse Ranges, California: Implications for basin morphology and tectonic history

    SciTech Connect

    Reed, W.E.; Campbell, M.D. . Dept. of Earth and Space Sciences)

    1993-04-01

    Compositional analyses reveal that Upper Cretaceous sediments exposed in the Western Transverse Ranges of CA were deposited in submarine fan systems in a forearc basin. Point count data suggest a magmatic arc/recycled orogen as the dominant provenance for these sediments. Paleocurrent measurements from conglomerates in these sediments yield a northerly transport direction. Removal of ca. 90[degree] of clockwise rotation and 70 km of right-lateral slip restore this section to a position west of the San Diego area. The forearc basin would have had a N-S orientation, with the bulk of sediments supplied by the Peninsular Ranges to the east. Evidence of the erosion of the accretionary wedge is provided by the presence of large, internally stratified olistoliths of Franciscan material interbedded with and surrounded by upper Cretaceous conglomerate. Petrographic, quantitative SEM, and microprobe analyses indicate the presence of diagnostic Franciscan mineralogy, including glaucophane, riebeckite, lawsonite, and serpentine. Olistoclasts of chert, jadeitic graywacke, serpentine, and blueschist are found intermixed with the conglomerates in close association with the olistoliths. This association provides strong field evidence that recirculation of melange material within the subduction zone was active and well-established by late Cretaceous time. Inferences regarding the forearc system morphology can be drawn from these observations. The occurrence of coarse, easterly-derived conglomerates surrounded by large, stratified, but sheared, westerly-derived Franciscan debris, suggests a narrow, relatively steep-sided basin. Paleocurrent measurements gave no indication of axial transport within the basin. This morphology suggests that, in late Cretaceous time, the forearc basin was youthful, with a narrow arc-trench gap. Thus, relative convergence rates between the North American and Pacific plates were possibly slower than Tertiary convergence rates.

  1. Trace elements geochemistry of kerogen in Upper Cretaceous sediments, Chad (Bornu) Basin, northeastern Nigeria: Origin and paleo-redox conditions

    NASA Astrophysics Data System (ADS)

    Adegoke, Adebanji Kayode; Abdullah, Wan Hasiah; Hakimi, Mohammed Hail; Sarki Yandoka, Babangida M.; Mustapha, Khairul Azlan; Aturamu, Adeyinka Oluyemi

    2014-12-01

    Trace element contents in isolated kerogen from Upper Cretaceous sediments within Gongila and Fika formations in the Chad (Bornu) Basin, northeastern Nigeria were determined using Inductively-coupled plasma mass spectrometer (ICP-MS), in order to infer the origin of the organic matter and the paleo-redox conditions during their sedimentation. The concentrations of the elements in the kerogen samples varied from 1.01 to 24,740 ppm. The distribution of elements shows that Fe is the most abundant element in Chad (Bornu) Basin kerogen, followed by Ce. Among the biophile elements, V is the most abundant, followed by Ni and Co in that order. Statistical evaluation of the elemental composition data shows that As, Ce, Pb, V, Cr, Fe, Co, Ni and U exhibit good positive correlations with each other. Molybdenum, on the other hand displays no obvious correlation with most of the trace elements determined including TOC, but has good positive correlation with TS and negative correlation with Tmax, Ce and Th, which suggests that the concentration of Mo decreases with increasing maturity and vice versa. Some trace element concentrations and their ratios suggest mixed marine and terrigenous source input for the organic matter (kerogen) in Chad (Bornu) Basin. More so, the concentrations of redox-sensitive elements, such as V, Ni, Cu, Cr Mo and Mn, in the kerogen samples suggest dysoxic bottom water conditions within the Gongila and Fika sediments. Cross-plots of V and Ni and V/(V + Ni) ratio also indicate that the organic matter of these samples was deposited in slightly reducing environments.

  2. Cathodoluminescence characterization of quartz grains from the Upper Cretaceous of dinosaur fossil localities in the Gobi desert, Mongolia

    NASA Astrophysics Data System (ADS)

    Saneyoshi, M.; Nishido, H.; Masuda, R.; Tsogtbaatar, K.; Chinzorig, T.

    2013-12-01

    The Upper Cretaceous eolian sediments in Mongolia's Gobi desert are one of the most important occurrences of the dinosaurs in the world. Large numbers of confiscated dinosaur fossils illegally worked out by poachers has been stored in the Mongolian Paleontological Center at Ulaanbaatar. In most cases, their localities are unknown. The purpose of this study is to identify their localities by cathodoluminescence (CL) features of quartz grains attached to the dinosaur specimens by comparing to the quartz samples collected from the sediments of circumjacent resources in this area. This study focuses on the confiscated specimen which makes up the nest with the babies' Protoceratops. Most of all Protoceratops in every growth process, have been discovered from the Djadokhta Formation in the Gobi desert. This formation crops out at Tugrikin Shireh and Bayn Dzak in the central part of the Gobi desert, and is derived from medium- to fine-grained sand mainly composed of quartz grains, of which sedimentary environments should be obvious to be eolian. The formation age of the sand beds at Tugrikin Shireh and Bayn Dzak has been estimated to be Middle Campanian. CL spectra of quartz have been demonstrated to show different features between the quartz from hydrothermal, plutonic, volcanic and metamorphic origins, suggesting the spectra reflect the condition of the quartz formation and the local environment. Therefore, we have applied the CL characterization of quartz grains to the evaluation of the provenance of the desert sediments. The quartz grains after sieving (#60-80 mesh size) were embedded in the brass holders with non-luminescent epoxy resin, and their surfaces were polished with 1 μm diamond abrasive. Color CL images obtained by the Luminoscope exhibit blue, violet and red emissions in the grains, suggesting various types of emission centers in the quartz. SEM-CL analysis was conducted using an SEM (JSM-5410) combined with a grating monochromator (Mono CL2) to measure

  3. Desiccation cracks in vertic palaeosols of the Cretaceous Hasandong Formation, Korea: genesis and palaeoenvironmental implications

    NASA Astrophysics Data System (ADS)

    Paik, In Sung; Lee, Yong Il

    1998-07-01

    The Hasandong Formation (Upper Cretaceous), Korea contains diagnostic vertic features such as pedogenic slickensides, pseudoanticlines, and large desiccation cracks. The Hasandong vertic palaeosols developed on floodplain deposits and display a diverse range of desiccation cracks, including calcite-filled, vertically stratified, and thin varieties. The calcite-filled cracks are 5-10 cm wide on the surface and up to 60 cm deep, and may have been formed by selective calcite precipitation in the cracks due to preferential vegetation. The vertically stratified cracks are those with crack-fillings having alternating sandstone and mudstone subparallel to crack walls. They are interpreted to have been formed by repeated crack opening and filling at crack margins due to seasonal drying and wetting. The thin cracks are less than 1 mm to a few mm wide and a few cm long, and are recognized by light colour mottling around them. Thin crack development may have resulted from intermittent incomplete cracking during sedimentation. The Hasandong vertic palaeosols have stratigraphic and lateral variations in vertic features, which are attributed to the changes in palaeoenvironments. Deep and large desiccation cracks with unbridged sediment-infilling formed in flood basins. The low topographic position of the distal floodbasin area resulted in weakly developed vertic palaeosols with calcite-filled desiccation cracks and some rhizocretions, and proximal location to a main channel may be responsible for rare development of deep and wide cracks and intercalation with calcrete-intraclast conglomerates. Differences in these vertic features along with interbedded calcic palaeosols may provide useful criteria for the palaeoenvironmental changes in and correlation of the floodplain deposits.

  4. Spectroscopic studies of wood fossils from the Crato Formation, Cretaceous Period.

    PubMed

    da Silva, J H; Freire, P T C; Abagaro, B T O; Silva, J A F; Saraiva, G D; de Lima, F J; Barros, O A; Bantim, R A; Saraiva, A A F; Viana, B C

    2013-11-01

    In this work we study two types of wood fossils (Gymnosperms, Araucariaceae) from the Crato Formation of Araripe Basin in Brazil, from the Cretaceous Period. The samples were characterized by Raman and infrared spectroscopies, X-ray diffraction and scanning electron microscopy. The results obtained by different techniques showed that although the rocks surrounding the fossils have predominantly the same constitution - calcite - however, the formation processes of these types of wood fossils are quite different. One of the fossils, denominated as light wood, is predominantly composed of gypsum, while the other fossil, the dark wood, is rich in amorphous carbon, possibly the kerogen type. Implications relative to the environment where the plants lived millions years ago are also given. Finally, the results highlight the constitution of one of the most important paleontological sites of the Cretaceous Period in the South America.

  5. Spectroscopic studies of wood fossils from the Crato Formation, Cretaceous Period.

    PubMed

    da Silva, J H; Freire, P T C; Abagaro, B T O; Silva, J A F; Saraiva, G D; de Lima, F J; Barros, O A; Bantim, R A; Saraiva, A A F; Viana, B C

    2013-11-01

    In this work we study two types of wood fossils (Gymnosperms, Araucariaceae) from the Crato Formation of Araripe Basin in Brazil, from the Cretaceous Period. The samples were characterized by Raman and infrared spectroscopies, X-ray diffraction and scanning electron microscopy. The results obtained by different techniques showed that although the rocks surrounding the fossils have predominantly the same constitution - calcite - however, the formation processes of these types of wood fossils are quite different. One of the fossils, denominated as light wood, is predominantly composed of gypsum, while the other fossil, the dark wood, is rich in amorphous carbon, possibly the kerogen type. Implications relative to the environment where the plants lived millions years ago are also given. Finally, the results highlight the constitution of one of the most important paleontological sites of the Cretaceous Period in the South America. PMID:23856041

  6. Cretaceous source rocks in Pakistan

    SciTech Connect

    Kari, I.B. )

    1993-02-01

    Pakistan is located at the converging boundaries of the Indian, Arabian, and Eurasian plates. Evolution of this tectonic setting has provided an array of environmental habitats for deposition of petroleum source rocks and development of structural forms. The potential Cretaceous source rocks in Central and South Indus Basin are spread over an area of about 300,000 km[sup 2]. With 2% cutoff on Total Organic Carbon, the average source rock thickness is 30-50 m, which is estimated to have generated more than 200 billion bbl of oil equivalent. To date, production of more than 30,000 bbl of oil and about 1200 million ft[sup 3] of gas per day can be directly attributed to Cretaceous source. This basin was an area of extensional tectonics during the Lower to Middle Cretaceous associated with slightly restricted circulation of the sea waters at the north-western margin of Indian Plate. Lower Cretaceous source rocks (Sembar Formation) were deposited while the basin was opening up and anoxia was prevailing. Similarly Middle to Upper Cretaceous clastics were deposited in setting favorable for preservation of organic matter. The time and depth of burial of the Cretaceous source material and optimum thermal regime have provided the requisite maturation level for generation of hydrocarbons in the basin. Central Indus basin is characterized by Cretaceous source rocks mature for gas generation. However, in South Indus Basin Cretaceous source rocks lie within the oil window in some parts and have gone past it in others.

  7. Paleomagnetic study of some Cretaceous and Tertiary sedimentary rocks of the Klamath Mountains province, California.

    USGS Publications Warehouse

    Mankinen, E.A.; Irwin, W.P.

    1982-01-01

    Paleomagnetic investigation of Cretaceous outliers and Tertiary sedimentary strata of the Klamath Mountains province, and of onlapping Cretaceous strata, has shown the rocks to be largely remagnetized. Samples studied are from the Upper Jurassic to Upper Cretaceous Great Valley sequence, Upper Cretaceous Hornbrook Formation, Eocene Montgomery Creek Formation, and Oligocene(?) Weaverville Formation. Cretaceous samples that survived the remagnetization have a mean remanence direction that is very close to the expected direction of the Cretaceous magnetic field at the locality of the Klamath Mountains. Data from both primary and remanetized samples suggest the possiblity of 11.5o+ or -15.8o of post-Cretaceous clockwise rotation of the Klamath Mountains province. -Authors

  8. Huminite reflectance measurements of Paleocene and Upper Cretaceous coals from borehole cuttings, Zavala and Dimmit counties, South Texas

    USGS Publications Warehouse

    Hackley, Paul C.; Hook, Robert W.; Warwick, Peter D.

    2005-01-01

    The reflectance of huminite in 19 cuttings samples was determined in support of ongoing investigations into the coal bed methane potential of subsurface Paleocene and Upper Cretaceous coals of South Texas. Coal cuttings were obtained from the Core Research Center of the Bureau of Economic Geology, The University of Texas at Austin. Geophysical logs, mud-gas logs, driller's logs, completion cards, and scout tickets were used to select potentially coal-bearing sample suites and to identify specific sample depths. Reflectance measurements indicate coals of subbituminous rank are present in a wider area in South Texas than previously recognized.

  9. Lithostratigraphy, biostratigraphy and chemostratigraphy of Upper Cretaceous and Paleogene sediments from southern Tanzania: Tanzania Drilling Project Sites 27-35

    NASA Astrophysics Data System (ADS)

    Jimènez Berrocoso, Àlvaro; Huber, Brian T.; MacLeod, Kenneth G.; Petrizzo, Maria Rose; Lees, Jacqueline A.; Wendler, Ines; Coxall, Helen; Mweneinda, Amina K.; Falzoni, Francesca; Birch, Heather; Singano, Joyce M.; Haynes, Shannon; Cotton, Laura; Wendler, Jens; Bown, Paul R.; Robinson, Stuart A.; Gould, Jeremy

    2012-07-01

    The 2008 Tanzania Drilling Project (TDP) expedition recovered common planktonic foraminifera (PF), calcareous nannofossils (CN) and calcareous dinoflagellates with extraordinary shell preservation at multiple Cenomanian-Campanian sites that will be used for paleoclimatic, paleoceanographic, and biostratigraphic studies. New cores confirm the existence of a more expanded and continuous Upper Cretaceous sequence than had previously been documented in the Lindi and Kilwa regions of southeastern coastal Tanzania. This TDP expedition cored 684.02 m at eight Upper Cretaceous sites (TDP Sites 28-35) and a thin Paleocene section (TDP Site 27). TDP Sites 29, 30, 31 and 34 together span the lowermost Turonian to Coniacian (PF Whiteinella archaeocretacea to Dicarinella concavata Zones and CN Zones UC6a-9b), with TDP Site 31 being the most biostratigraphically complete Turonian section found during TDP drilling. A discontinuous section from the Santonian-upper Campanian (PF D. asymetrica to Radotruncana calcarata Zones and CN Zones UC12-16) was collectively recovered at TDP Sites 28, 32 and 35, while thin sequences of the lower Cenomanian (PF Thalmanninella globotruncanoides Zone and CN subzones UC3a-b) and middle Paleocene (Selandian; PF Zone P3a and CN Zone NP5) were cored in TDP Sites 33 and 27, respectively. Records of δ13Corg and δ13Ccarb from bulk sediments generated for all the Cretaceous sites show largely stable values through the sections. Only a few parallel δ13Corg and δ13Ccarb shifts have been found and they are interpreted to reflect local processes. The δ18Ocarb record, however, is consistent with Late Cretaceous cooling trends from the Turonian into the Campanian. Lithologies of these sites include thick intervals of claystones and siltstones with locally abundant, finely-laminated fabrics, irregular occurrences of thin sandstone layers, and sporadic bioclastic debris (e.g., inoceramids, ammonites). Minor lithologies represent much thinner units of up to

  10. Evaluation of bio-molecular signatures and hydrocarbon potential of upper Cretaceous shale, NE Nigeria

    NASA Astrophysics Data System (ADS)

    Boboye, Olugbenga A.; Nzegwu, Uche A.

    2014-11-01

    The Bornu Basin is a sector of the Chad Basin located in the northeastern part of Nigeria, occupying about one-tenth of total area in Chad Basin. Twenty-eight representative shale cutting samples retrieved from Tuma-1, Sa-1 and Albarka-1 exploratory wells were analyzed. Seventeen shale samples systematically selected from Gongila, Fika Shale and Chad Formations were subjected to Total Organic Content (TOC), Rock-Eval pyrolysis, Soluble Organic Matter, Liquid Chromatography, Gas Chromatography and Gas Chromatography/Mass Spectrometry analyses. This is to characterize and assess the potential capability of the shale units. The results showed that TOC of the Coniacian-Paleocene shale units exceed the threshold (0.5 wt%) needed for petroleum generation. This classifies it as potential source beds. Evidence from biomarkers indicates a preponderance of marine organic matter with subordinate terrigenous input. The quantity of gammacerane occurrence suggests normal saline environment. The presence of oleanane index indicates angiosperms input into Cretaceous-Tertiary source rock. C35/C34 homohopane ratio showed the anoxia development towards the center of the basin. C29ααα (20R)/C27ααα (20R) sterane ratio indicate the dominance of marine organic matter with subordinate terrigenous input. The 22S/(22S + 22R) ratio of C31 hopane have not reached equilibrium as evident by immaturity to early mature stages from diagnostic ratios of βα moretane/αβ hopane, Ts/(Ts + Tm), 28,30-bisnorhopanes/17α-hopanes, diasteranes/regular steranes, ααα steranes/αββ steranes and 20S/(20S + 20R) C29 regular steranes respectively. This is corroborated with the Rock-Eval indices showing immature to earlier mature kerogen within the Fika Formation. It consists preeminently of Type IV, with subordinate Type III. The prospect for hydrocarbon in this part of the basin is only fair to moderate with potential for gaseous rather than liquid hydrocarbon.

  11. Osteology of Huabeisaurus allocotus (Sauropoda: Titanosauriformes) from the Upper Cretaceous of China

    PubMed Central

    D'Emic, Michael D.; Mannion, Philip D.; Upchurch, Paul; Benson, Roger B. J.; Pang, Qiqing; Zhengwu, Cheng

    2013-01-01

    Background The Late Cretaceous titanosauriform sauropod Huabeisaurus allocotus Pang and Cheng is known from teeth and much of the postcranial skeleton. Its completeness makes it an important taxon for integrating and interpreting anatomical observations from more fragmentary Cretaceous East Asian sauropods and for understanding titanosauriform evolution in general. Methodology/Principal Findings We present a detailed redescription of Huabeisaurus allocotus and a suite of anatomical comparisons with other titanosauriforms that demonstrate its validity via autapomorphies (e.g., division of some presacral vertebral laminae, reduced development of caudal ribs, the development of fossae relative to one another in caudal vertebral neural arches, high tibia-to-femur ratio). Huabeisaurus shares many features with other Cretaceous East Asian sauropods (e.g., pendant cervical ribs, anterior-middle caudal vertebrae with a nearly flat anterior centrum face and a concave posterior centrum face) that are absent in sauropods from other landmasses and strata, suggesting a close relationship among many of these forms within the clade Somphospondyli. Conclusions/Significance Restudy of Huabeisaurus provides further evidence for the existence of a clade of somphospondylans – Euhelopodidae – mainly found in the Cretaceous of East Asia. Euhelopodidae represents a fourth example of the evolution of narrow crowns within Sauropoda, along with diplodocoids, brachiosaurids, and advanced titanosaurs (lithostrotians). Despite being known from fewer species than Diplodocoidea, Brachiosauridae, or Lithostrotia, euhelopodids possessed a broader range of tooth shapes than any of these clades, suggesting that euhelopodids exemplified a comparably broad range of feeding strategies and perhaps diets. PMID:23936326

  12. The Tethyan Upper Cretaceous in northwestern Turkey - an integrated study of pelagic sections in northwestern Anatolia and the southern Black Sea coast

    NASA Astrophysics Data System (ADS)

    Wolfgring, Erik; Böhm, Katharina; Ömer Yilmaz, Ismael; Tüysüz, Okan; Dinarès-Turell, Jaume; Wagreich, Michael

    2016-04-01

    Upper Cretaceous sections in northwestern Turkey record pelagic depositional environments that are characterised by frequent volcanic events. The aim of the ongoing project is to cover a continuous cyclostratigraphic record of the Tethyan Campanian and to date palaeoenvironmental changes and volcanic events. Cyclic successions of pelagic deposits depicting shales and marl-marly limestone alternations with inter bedded tuff and turbidite layers were logged. Deposits alongside the southern Black Sea coast (in the western Pontide orogen) and in northwestern Anatolia (Göynük and Nallihan area) were examined for geochemistry and mineralogy of tuff beds, as well as for biostratigraphy and palaeoecology. Three formations of Turonian to Campanian age in the western Pontide area are present; Dereköy, Unaz and Cambu Formation are reflecting different geodynamic phases, i.e. subduction of the Neotethys as well formation of the Western Black Sea basin, overlain by the late Campanian-Maastrichtian Akveren Formation. Planktonic foraminiferal data suggest an age of upper Turonian Marginotruncana sigali -Dicarinella primitiva to lower Campanian Globotruncanita elevata Zone bracketing the first major phase of volcanism (Dereköy Fm.). The second volcanic unit (Cambu Fm.) is of early Campanian age, when spreading in the western Black Sea basin started. Geochemistry of tuff layers confirms magmatic activity of the Pontide volcanic arc from Turonian to Campanian. Discrimination diagrams using immobile elements classify calc-alkaline magma series and balsaltic-andesite and basalt rock types. Northwestern Anatolian sections are located in the Central Sakyrya region's Mudurnu-Göynük basin. Upper Cretaceous deposits of Turonian to Campanian age are recorded in pelagic limestones of the Yenipazar Formation. The cyclic pelagic Göynük section covers the Santonian-Campanian boundary, followed by a lower Campanian volcano-clastic unit and overlying turbidites and pelagic shales of late

  13. Titanosaur osteoderms from the Upper Cretaceous of Lo Hueco (Spain) and their implications on the armor of Laurasian titanosaurs.

    PubMed

    Vidal, Daniel; Ortega, Francisco; Sanz, José Luis

    2014-01-01

    Titanosaurs are the only sauropod dinosaurs known to bear a dermal armor. Their osteoderms are relatively rare finds, with few more than a hundred specimens recovered worldwide. Also, little is known about their intra-individual, intra-specific or inter-specific variability. The macrovertebrate site of Lo Hueco (Upper Cretaceous; Cuenca, Spain) has yielded several complete specimens of osteoderms, some associated with fairly articulated specimens. They are all variations of the morphotype known as bulb and root. The presence of only this morphotype in Europe, which is considered as the primitive condition among titanosaurs, seems to indicate that the known Upper Cretaceous Laurasian titanosaurs only bore these referred bulb and root osteoderms. An eliptic Fourier analysis on the outline of complete specimens from this morphotype reveals: i) that they truly are part of a morphological cline; and ii) the existence of a consistent correlation between the outline and the morphology of the bulb. Such variation along a cline is more consistent with intra-individual rather than inter-specific variation. The osteoderms associated with a single titanosaur individual from Lo Hueco reinforce this hypothesis. PMID:25118985

  14. Titanosaur Osteoderms from the Upper Cretaceous of Lo Hueco (Spain) and Their Implications on the Armor of Laurasian Titanosaurs

    PubMed Central

    Vidal, Daniel; Ortega, Francisco; Sanz, José Luis

    2014-01-01

    Titanosaurs are the only sauropod dinosaurs known to bear a dermal armor. Their osteoderms are relatively rare finds, with few more than a hundred specimens recovered worldwide. Also, little is known about their intra-individual, intra-specific or inter-specific variability. The macrovertebrate site of Lo Hueco (Upper Cretaceous; Cuenca, Spain) has yielded several complete specimens of osteoderms, some associated with fairly articulated specimens. They are all variations of the morphotype known as bulb and root. The presence of only this morphotype in Europe, which is considered as the primitive condition among titanosaurs, seems to indicate that the known Upper Cretaceous Laurasian titanosaurs only bore these referred bulb and root osteoderms. An eliptic Fourier analysis on the outline of complete specimens from this morphotype reveals: i) that they truly are part of a morphological cline; and ii) the existence of a consistent correlation between the outline and the morphology of the bulb. Such variation along a cline is more consistent with intra-individual rather than inter-specific variation. The osteoderms associated with a single titanosaur individual from Lo Hueco reinforce this hypothesis. PMID:25118985

  15. "Kasserine Island" boundaries variations during the Upper Cretaceous-Eocene (central Tunisia)

    NASA Astrophysics Data System (ADS)

    Kadri, Ali; Essid, El Mabrouk; Merzeraud, Gilles

    2015-11-01

    The emergent domain known as "Kasserine Island" in central Tunisia, to the West of the North-South Axis, was emerging during the Turonian. This area has undergone several changes during the Cretaceous-Eocene period. In the present study, the compilation of surface and sub-surface data provided new information about the boundaries variations of the emerged domain. The analysis of paleogeographic maps allowed the identification of three distinct stages of evolution. The first stage extents from the Middle Turonian to the Lower Maastrichtian where the emergent domain covers the area extending from Jebels Selloum-Sidi Aich in the West to Jebel Bouhedma in the East. The boundaries of this area coincide with the E-W Kasserine fault to the North, the N-S Lessouda-Boudinar fault in the East and the N 120 el Mech-Souinia flexure at the South. This emersion contemporaneous with a high eustatic level is most likely related to tectonic activity. The extensional tectonic regime that is characterized by a NE-SW minimal horizontal stress, has reactivated border faults with a normal component. The interference of the tilting of these border faults was at the origin of the emergence of this domain. The ascent of the Triassic salt may also have contributed in this uplift. In the second stage, the emerged domain has reached its maximum expansion to the North, the West and the South during the Middle Maastrichtian-Paleocene period. Its northern limit is irregular, while the southern limit coincides with the N120 Gafsa fault and the E-W fault of Jebels Orbata-Bouhedma. The N-S Lessouda-Boudinar fault forms the eastern limit. This expansion is mostly related to the global eustatic fall that is well characterized during this period, and partly to the compressive tectonic activity. The Lower Eocene is characterized by a marine transgression that has interested the northern edge of the Island, where the Ypresian deposits are discordant on older series. This edge was irregular and marked by

  16. Palaeoclimatic changes during the Upper Cretaceous of eastern Denmark: a study based on the Stevns-2 chalk core

    NASA Astrophysics Data System (ADS)

    Boussaha, M.; Stemmerik, L.; Thibault, N.

    2013-12-01

    The Stevns-2 core located in eastern Denmark penetrated close to 350 m of upper Campanian-Maastrichtian sediments of the upper Chalk Group (Stemmerik et al., 2006). The calcareous nannofossil biozonation spans the time interval from the UC16aBP from the upper Campanian to the NNT1 in the lowermost Danian. Carbon and Oxygen isotopes trends records climatic events occurring in the upper Cretaceous: (1) the Late Campanian warm climatic optimum, (2) the early Maastrichtian cooling event, (3) the mid-Maastrichtian warming event, and (4) the late Maastrichtian cooling event, also observed in the nearby Stevns-1 core (Thibault et al., 2011) . These climatic variations match closely those observed in the nearby Stevns-1 core and in the Atlantic, Pacific and Tethyan realms (Thibault & GARDIN, 2006; Thibault et al., 2011). Changes occurring in the number of observed Inoceramids prisms per meter of core section, in the abundance of calcareous nannofossils and in the visible trace fossils abundances seem to be linked to climatic changes as expressed in the δ18O of the bulk sediment. In addition to the sedimentological data show that the distribution of facies through time from: (1) cyclic marl alternating with mudstone-wackestone chalk and conglomerates, to (2) bioturbated white mudstone and wackestone chalk, then to (3) flint alternating with mudstone and wackestone chalk, ending with (5) bryozoans wackestone and packstone, and the sedimentation rate changes varying from 1.4 cm/kyr to 13.4 cm/kyr. Here we show how changes in the sedimentology of the chalk and abundances of different fossil group are influenced by global and regional mechanisms. Isotopic results mainly reflect global paleoclimatic changes, whereas the sedimentological record is mostly influenced by (1) local variations in paleoproductivity, (2) deep-water paleocurrents influencing the chalk deposition and the shape of the sea-floor, (3) and (4) the geodynamic activity and paleotopography of the Late

  17. Upper Cretaceous exhumation of the western Rhodope Metamorphic Province (Chalkidiki Peninsula, northern Greece)

    NASA Astrophysics Data System (ADS)

    Kydonakis, Konstantinos; Gallagher, Kerry; Brun, Jean-Pierre; Jolivet, Marc; Gueydan, Frédéric; Kostopoulos, Dimitrios

    2014-06-01

    The Vertiskos Unit of northern Greece is an elongated basement belt with a complex poly-metamorphic history. It extends from Greece (Chalkidiki peninsula), to the south, up to Serbia, in the north, and arguably represents the westernmost part of the Rhodope Metamorphic Province (northern Greece to southern Bulgaria). The Vertiskos Unit experienced a medium pressure lower amphibolite-facies metamorphic overprint during the Alpine Orogeny. The available medium-temperature geochronology implies that it remained at temperature of approximately 300°C (or slightly higher) during Lower Cretaceous. In order to constrain its post-Lower Cretaceous thermal history, until near-surface exposure, we applied apatite fission track analysis. The central ages obtained range from 68.5 ± 3.8 to 46.6 ± 3.6 Ma (uppermost Cretaceous to Middle Eocene) and mean track lengths between 13 and 13.5 µm. We applied two inverse thermal modeling approaches using either each sample independently (high degree of freedom in the thermal history, better data fit) or all samples together interpreting them as a vertical profile (simpler thermal history, worse data fit). Irrespective of the modeling approach, we conclude that the bulk thermal history of the Vertiskos Unit crosses the high-temperature limit of the apatite partial annealing zone by the uppermost Cretaceous and reaches near-surface conditions as early as lower/middle Eocene. These results contrast with the thermal history of the other domains of the Rhodope Metamorphic Province further east (namely the Southern Rhodope Core Complex and the Northern Rhodope Complex) and establish the Vertiskos basement complex as the oldest exhumed coherent basement fragment of the Rhodope Metamorphic Province and Greece.

  18. A New Basal Ankylosaurid (Dinosauria: Ornithischia) from the Lower Cretaceous Jiufotang Formation of Liaoning Province, China

    PubMed Central

    Han, Fenglu; Zheng, Wenjie; Hu, Dongyu; Xu, Xing; Barrett, Paul M.

    2014-01-01

    A new ankylosaurid, Chuanqilong chaoyangensis gen. et sp. nov., is described here based on a nearly complete skeleton from the Lower Cretaceous Jiufotang Formation of Baishizui Village, Lingyuan City, Liaoning Province, China. Chuanqilong chaoyangensis can be diagnosed on the basis of two autapomorphies (glenoid fossa for quadrate at same level as the dentary tooth row; distally tapering ischium with constricted midshaft) and also a unique combination of character states (slender, wedge-like lacrimal; long retroarticular process; humerus with strongly expanded proximal end; ratio of humerus to femur length  = 0.88). Although a phylogenetic analysis places Chuanqilong chaoyangensis as the sister taxon of the sympatric Liaoningosaurus near the base of the Ankylosauridae, the two taxa can be distinguished on the basis of many features, such as tooth morphology and ischial shape, which are not ontogeny-related. Chuanqilong chaoyangensis represents the fourth ankylosaurid species reported from the Cretaceous of Liaoning, China, suggesting a relatively high diversity in Cretaceous Liaoning. PMID:25118986

  19. Constraining the Geological Time Scale for the Upper Cretaceous in the Edmonton Group: Western Canadian Sedimentary Basin

    NASA Astrophysics Data System (ADS)

    Heredia, B.; Gaylor, J. R.; Hilgen, F.; Kuiper, K.; Mezger, K.; Wijbrans, J. R.; Quidelleur, X.; Huesing, S.

    2011-12-01

    The Cretaceous period records evidence of sea-level changes, remarkably cyclic sedimentation, major perturbations in carbon cycles during anoxic events, and large scale igneous activity. Astronomically-tuned time scales are only partially consistent with recalculated Ar-Ar constraints for the Cretaceous-Paleogene (K-Pg) boundary, but differ in number and tuning of 405-kyr eccentricity related cycles. The exposures of Upper Cretaceous strata along the Red Deer River (Western Canadian Sedimentary Basin) offer a unique opportunity to examine aspects of marine, tectonic, and climatic influenced sediments. The uppermost part of the Knudsen Farm section is a well-preserved continuous section, mainly composed by climatically controlled alternations of silt and organic rich horizons, in which altered volcanic ash layers have been deposited. In this section, the K-Pg boundary has been placed at the base of a prominent coal layer (Nevis coal), approx. 24 m from the base of the c29r. We present a compilation of paleomagnetic data, chemical, colour and magnetic susceptibility proxies, and Ar-Ar, K-Ar and U-Pb (CA-TIMS) for the uppermost part of the Maastrichtian, including the base of the c29r to the K-Pg boundary and up to the lowermost Danian. High-resolution radioisotopic ages and the multi-proxy lithological and geochemical datasets are used to develop a cyclostratigraphic reconstruction of this interval, thus permitting the synchronisation of rock clocks close to the K-Pg boundary. This research is funded by the European Community's Seventh Framework Program (FP7/2007-2013) under grant agreement no [215458].

  20. Authigenic kaolinite and associated pyrite in chalk of the Cretaceous Niobrara Formation, Eastern Colorado.

    USGS Publications Warehouse

    Pollastro, R.M.

    1981-01-01

    Cores from the Smoky Hill Chalk Member of the Cretaceous Niobrara Formation have several zones containing authigenic kaolinite as spherical, moldic, polycrystalline aggregates that occur within single or multichambered foraminiferal tests and are commonly associated with framboidal pyrite. Such kaolinite is inferred to result from volcanic ash deposited during chalk sedimentation. Shortly after burial, a colloidal aluminous gel or solution formed from the unstable ash and moved into organic-rich foraminiferal tests, where sulfate-reducing bacteria created a favorable microenvironment for the simultaneous crystallization of kaolinite and pyrite. -Author

  1. A New Leptoceratopsid (Ornithischia, Ceratopsia) with a Unique Ischium from the Upper Cretaceous of Shandong Province, China.

    PubMed

    He, Yiming; Makovicky, Peter J; Wang, Kebai; Chen, Shuqing; Sullivan, Corwin; Han, Fenglu; Xu, Xing

    2015-01-01

    The partial skeleton of a leptoceratopsid dinosaur, Ischioceratops zhuchengensis gen. et sp. nov., was excavated from the bone-beds of the Upper Cretaceous Wangshi Group of Zhucheng, Shandong Province, China. This fossil represents the second leptoceratopsid dinosaur specimen recovered from the Kugou locality, a highly productive site in Zhucheng. The ischium of the new taxon is morphologically unique among known Dinosauria, flaring gradually to form an obturator process in its middle portion and resembling the shaft of a recurve bow. An elliptical fenestra perforates the obturator process, and the distal end of the shaft forms an axehead-shaped expansion. The discovery of Ischioceratops increases the known taxonomic diversity and morphological disparity of the Leptoceratopsidae. PMID:26701114

  2. A New Leptoceratopsid (Ornithischia, Ceratopsia) with a Unique Ischium from the Upper Cretaceous of Shandong Province, China

    PubMed Central

    He, Yiming; Makovicky, Peter J.; Wang, Kebai; Chen, Shuqing; Sullivan, Corwin; Han, Fenglu; Xu, Xing

    2015-01-01

    The partial skeleton of a leptoceratopsid dinosaur, Ischioceratops zhuchengensis gen. et sp. nov., was excavated from the bone-beds of the Upper Cretaceous Wangshi Group of Zhucheng, Shandong Province, China. This fossil represents the second leptoceratopsid dinosaur specimen recovered from the Kugou locality, a highly productive site in Zhucheng. The ischium of the new taxon is morphologically unique among known Dinosauria, flaring gradually to form an obturator process in its middle portion and resembling the shaft of a recurve bow. An elliptical fenestra perforates the obturator process, and the distal end of the shaft forms an axehead-shaped expansion. The discovery of Ischioceratops increases the known taxonomic diversity and morphological disparity of the Leptoceratopsidae. PMID:26701114

  3. Heteromorph ammonites from the Upper Campanian (Upper Cretaceous) Baculites cuneatus and Baculites reesidei zones of the Pierre Shale in Colorado, USA

    USGS Publications Warehouse

    Kennedy, W.J.; Cobban, W.A.; Scott, G.R.

    2000-01-01

    Calcareous sandstone concretions in the Upper Cretaceous Pierre Shale in Middle Park and in the Fort Collins area of Colorado in the U.S. Western Interior contain heteromorph ammonites of the families Nostoceratidae HYATT, 1894, and Diplomoceratidae SPATH, 1926. The following species are described: Nostoceras cf. N. approximans (CONRAD, 1855), Nostoceras cf. N. obtusum HOWARTH, 1965, N. larimerense sp. nov., Nostoceras cf. N. splendidum (SHUMARD, 1861). Didymoceras aurarium sp. nov., D. draconis (STEPHENSON, 1941), Cirroceras conradi (MORTON, 1841), Anaklinoceras minutum sp. nov., Solenoceras texanum (SHUMARD, 1861), Solenoceras cf. S. reesidei STEPHENSON, 1941, Lewyites oronensis (LEWY, 1969), and Lewyites? sp. All these species are migrants from the Gulf coastal region. Didymoceras draconis and Cirroceras conradi are also known from the Delaware-New Jersey area, and these two species, together with Solenoceras texanum are known from as far away as Israel.

  4. Petrology and reservoir paragenesis in the Sussex B sandstone of the Upper Cretaceous Cody Shale, House Creek and Porcupine fields, Powder River basin, Wyoming

    SciTech Connect

    Not Available

    1992-01-01

    This book of reservoir paragenesis includes detailed descriptions of the petrology of depositional facies of the Sussex B sandstone of the Sussex Sandstone Member of the Upper Cretaceous Cody Shale in the House Creek and Porcupine fields, Powder River basin, Wyoming.

  5. Depositional framework of Upper Cretaceous fluvio-deltaic coals, south-central Alberta

    SciTech Connect

    Waheed, A.; Miall, A.D.

    1985-01-01

    Coal-bearing strata of the Horseshoe Canyon Formation near Drumheller represent a progradational fluvio-deltaic system. Lower delta-plain facies include meandering channels flanked by levees, crevasse splays and channels, bays, and well-drained and poorly-drained swamps. Upper delta-plain facies are similar except that flood basins and oxbow lakes replace bays. The ten main coal seams compose 5% of the section and are bituminous with 0.6-1.0% sulfur. They are up to 2 m thick and most extend across the 11 by 7 km area of detailed study. In order of importance, they represent bay-floor accumulations, interfleuve swamps, and oxbow-fills. In interchannel bays and flood basins, coal deposition was frequently interrupted either by influx of crevasse-sands or inundation by bays. Coal seams that accumulated in low-lying areas of flood basins are thin and are commonly interbedded with carbonaceous shales. Oxbow-fill coals are thin, lenticular and arcuate. Thickness and lateral continuity of fluvio-deltaic coals were controlled by crevassing, differential compaction, and post-depositional channel erosion. Flood basins and bays were distinguished with palynomorphs. Deltaic and fluvial channels are 1-6 m thick fining-upward sequences with well-developed epsilon cross-stratification. An embedded Markov chain analysis suggest strong asymmetrical ordering within the coal-bearing sequence. Facies paths indicate depositional control by such autocyclic and allocyclic processes as lateral accretion, crevassing, avulsion, subsidence, marine inundation, overbank flooding, water-table fluctuation, and growth and demise of vegetation.

  6. Cyclic deposits and hummocky cross-stratification of probable storm origins in Upper Cretaceous rocks of the Cape Sebastian area, southwestern Oregon.

    USGS Publications Warehouse

    Hunter, R.E.; Clifton, H.

    1982-01-01

    Cyclic deposits containing hummocky cross-stratification occur in the upper part of the Cape Sebastian Sandstone, a shallow marine transgressive sandstone of Late Cretaceous age on the southern Oregon coast. The cycles consist, where complete, of a lower hummocky cross-stratified sandstone, a middle planar- and ripple-bedded sandstone with a shale bed in its middle part, and an upper bioturbated sandstone. Depositional conditions are interpreted from the characteristics of these cycles. -from Authors

  7. Basin analysis of Upper Cretaceous strata of the Washakie and Red Desert basins, southwestern Wyoming, employing computer-generated maps and cross sections

    SciTech Connect

    Kohles, K.M.; Potts, J. ); Reid, F.S.

    1991-03-01

    The Washakie and Red Desert basins comprise the eastern portion of the Greater Green River basins of southwestern Wyoming. Stratigraphically the basins are dominated by a thick package of Cretaceous clastic sediments, as much as 16,000 ft thick, which resulted from several major transgressive-regressive cycles. Upper Cretaceous strata deposited during the latest cycle contain extensive deposits of commercial hydrocarbons, particularly gas. Much of the present structural configuration of the area is the result of the Laramide Orogeny in Late Cretaceous time. To facilitate a comprehensive geological analysis of the area a computerized subsurface data base was constructed from available well logs for approximately 3,000 wells in the Washakie and Red Desert basins. This data base contains correlated tops for most of the major Upper Cretaceous stratigraphic units, including selected subdivisions and net sand thickness values. Consistent correlations were achieved through the use of a tight, loop-tied cross section and key well network containing over 400 correlated well-logs. A complete suite of structure contour maps on all correlated horizons was generated from the data base with commercially available software. These maps, along with selected computer-generated structural cross sections, reveal a detailed subsurface picture of the Washakie and Red Desert basins. Isopachous maps of selected intervals were also produced to illustrate the Late Cretaceous depositional history of the area.

  8. Paleocurrent, petrography and provenance analyses of the Ajali Sandstone (Upper Cretaceous), southeastern Benue Trough, Nigeria

    NASA Astrophysics Data System (ADS)

    Amajor, L. C.

    1987-09-01

    Paleocurrent, petrographic and heavy-mineral analyses of the Ajali Sandstone (Late Cretaceous) in southeastern Nigeria show that the sedimentary rocks on the Santonian Okigwe-Abakaliki anticlinorium provided the major detritus, whereas minor contributions of the eastern Precambrian basement block (Oban massif) are confined along a narrow belt southeast of Alayi in the Afikpo Basin. The sandstones derived from the major sedimentary source are quartz arenites characterized by a zircon-tourmaline heavy-mineral assemblage and a radial paleocurrent pattern which parallels the paleoslope of the provenance. On the other hand, those sands generated from the eastern basement block are arkose and sub-arkose dominated by a garnet-apatite-rutile heavy-mineral assemblage and southwesterly directed paleocurrent modes. The results of this study support the previous hypothesis that most ancient quartz arenites are multicycle in origin.

  9. Early Cretaceous vegetation and climate change at high latitude: palynological evidence from Isachsen Formation, Arctic Canada

    NASA Astrophysics Data System (ADS)

    Galloway, Jennifer M.; Tullius, Dylan N.; Evenchick, Carol A.; Swindles, Graeme T.; Hadlari, Thomas; Embry, Ashton

    2015-04-01

    Understanding the behaviour of global climate during relatively warm periods in Earth's history, such as the Cretaceous Period, advances our overall understanding of the climate system and provides insight on drivers of climate change over geologic time. While it has been suggested that the Valanginian Age represents the first episode of Cretaceous greenhouse climate conditions with relatively equable warm temperatures, mounting evidence suggests that this time was relatively cool. A paucity of paleoclimate data currently exists for polar regions compared to mid- and low-latitudes and this is particularly true for the Canadian Arctic. There is also a lack of information about the terrestrial realm as most paleoclimate studies have been based on marine material. Here we present quantitative pollen and spore data obtained from the marginal marine and deltaic-fluvial Isachsen Formation of the Sverdrup Basin, Canadian Arctic, to better understand the long-term vegetation and climate history of polar regions during the warm but variable Early Cretaceous (Valanginian to Early Aptian). Detrended correspondence analysis of main pollen and spore taxa is used to derive three ecological groupings influenced by moisture and disturbance based on the botanical affinities of palynomorphs: 1) a mixed coniferous assemblage containing both lowland and upland components; 2) a conifer-filicopsid community that likely grew in dynamic lowland habitats; and, 3) a mature dry lowland community composed of Cheirolepidaceans. Stratigraphic changes in the relative abundance of pollen and spore taxa reflect climate variability in this polar region during the ~20 Mya history of the Isachsen Formation. The late Valanginian was relatively cool and moist and promoted lowland conifer-filicopsid communities. Warming in the Hauterivian resulted in the expansion coniferous communities in well-drained or arid hinterlands. A return to relatively cool and moist conditions in the Barremian resulted in the

  10. Revised nomenclature, definitions, and correlations for the Cretaceous formations in USGS-Clubhouse Crossroads #1, Dorchester County, South Carolina

    USGS Publications Warehouse

    Gohn, Gregory S.

    1992-01-01

    The stratigraphy of the Cretaceous section in a continuously cored stratigraphic test hole, USGS-Clubhouse Crossroads #1, is reviewed and amended herein. Located in southern Dorchester County, S.C., the Clubhouse Crossroads #1 core is one of the principal stratigraphic reference sections in the southern Atlantic Coastal Plain. Traditional and revised systems of stratigraphic nomenclature for the outcropping Cretaceous formations of the Carolinas are reviewed for their applicability in defining subsurface Cretaceous formations at Clubhouse Crossroads. The revised nomenclature, exemplified by the formations proposed by J. P. Owens in 1989 and by N. F. Sohl and Owens in 1991, is preferred for this purpose over the traditional nomenclature established by D.J.P. Swift and S.D. Heron, Jr., in 1969. The revised nomenclature is selected because of its greater emphasis on the historical succession of entire sedimentary systems (timeparallel formations), in contrast to the emphasis placed on the physical continuity of individual facies through time (time-transgressive formations) in the traditional nomenclature. Physical relationships between the two types of formations are discerned by using K.E. Caster's 1934 facies model, in which the time-transgressive units of the traditional model are his magnafacies and the time-parallel units of the revised model are sets of his laterally contiguous parvafacies. In 1977, G.S. Gohn and others and J.E. Hazel and others provisionally delineated Cretaceous formations in the Clubhouse Crossroads #1 core by using Swift and Heron's traditional units. The publication of additional lithologic and paleontologic data since 1977 for Cretaceous units in the core and for Cretaceous units throughout the Carolinas provides a basis for reviewing and amending the original definitions of the Cretaceous formations at Clubhouse Crossroads. Ages assigned to the Cretaceous units at Clubhouse Crossroads by Hazel and others are also reviewed. The boundaries

  11. First sauropod (Dinosauria: Saurischia) remains from the Guichón Formation, Late Cretaceous of Uruguay

    NASA Astrophysics Data System (ADS)

    Soto, Matías; Perea, Daniel; Cambiaso, Andrea

    2012-02-01

    We report the first sauropod remains recorded in the Guichón Formation, western Uruguay. The materials belong to a middle-sized sauropod represented by more than one individual, and among other remains include more than fifty caudal centra. Close to the bones, several eggshell fragments resembling Sphaerovum erbeniMones, 1980 were found. We discuss the biostratigraphic implications of these findings, which for the first time allow us to confidently refer the Guichón Formation to the Late Cretaceous. The combination of several synapomorphies such as a biconvex first caudal centrum, strongly procoelous middle and distal caudal centra, and a pyramidal astragalus suggests that the sauropod remains belong to a derived lithostrotian, probably related to Pellegrinisaurus powelli, Baurutitan britoi and Alamosaurus sanjuanensis. A few isolated teeth (now lost) referred by Frederich von Huene in 1934 to ornithomimid theropods and ornithischians are herein reinterpreted as belonging to indeterminate theropods and basal iguanodontians.

  12. Chronostratigraphic cross section of Cretaceous formations in western Montana, western Wyoming, eastern Utah, northeastern Arizona, and northwestern New Mexico, U.S.A.

    USGS Publications Warehouse

    Merewether, E. Allen; McKinney, Kevin C.

    2015-01-01

    In this transect for time-stratigraphic units of the Cretaceous, lateral changes in lithologies, regional differences in thicknesses, and the abundance of associated disconformities possibly reflect local and regional tectonic events. Examples of evidence of those events follow: (1) Disconformities and the absence of strata of lowest Cretaceous age in western Montana, western Wyoming, and northern Utah indicate significant tectonism and erosion probably during the Late Jurassic and earliest Cretaceous; ( 2) stages of Upper Cretaceous deposition in the transect display major lateral changes in thickness, which probably reflect regional and local tectonism.

  13. Architectural studies of Jurassic-Cretaceous fluvial units, Colorado Plateau

    SciTech Connect

    Miall, A.D.; Bromley, M.H.; Cowan, E.J.; Turner-Peterson, C.E.

    1989-03-01

    A sixfold hierarchy of architectural elements and bounding surfaces evolved from outcrop studies of three fluvial units: Westwater Canyon member (WCM), Morrison Formation, Upper Jurassic; Torrivio sandstone member (TSM), Gallup Sandstone, Upper Cretaceous, northwestern New Mexico; and Kayenta Formation (KF), Lower Jurassic, southwestern Colorado. This hierarchy is discussed.

  14. Stratigraphy and Facies of Cretaceous Schrader Bluff and Prince Creek Formations in Colville River Bluffs, North Slope, Alaska

    USGS Publications Warehouse

    Flores, Romeo M.; Myers, Mark D.; Houseknecht, David W.; Stricker, Gary D.; Brizzolara, Donald W.; Ryherd, Timothy J.; Takahashi, Kenneth I.

    2007-01-01

    Stratigraphic and sedimentologic studies of facies of the Upper Cretaceous rocks along the Colville River Bluffs in the west-central North Slope of Alaska identified barrier shoreface deposits consisting of vertically stacked, coarsening-upward parasequences in the Schrader Bluff Formation. This vertical stack of parasequence deposits represents progradational sequences that were affected by shoaling and deepening cycles caused by fluctuations of sea level. Further, the vertical stack may have served to stabilize accumulation of voluminous coal deposits in the Prince Creek Formation, which formed braided, high-sinuosity meandering, anastomosed, and low-sinuosity meandering fluvial channels and related flood plain deposits. The erosional contact at the top of the uppermost coarsening-upward sequence, however, suggests a significant drop of base level (relative sea level) that permitted a semiregional subaerial unconformity to develop at the contact between the Schrader Bluff and Prince Creek Formations. This drop of relative sea level may have been followed by a relative sea-level rise to accommodate coal deposition directly above the unconformity. This rise was followed by a second drop of relative sea level, with formation of incised valley topography as much as 75 ft deep and an equivalent surface of a major marine erosion or mass wasting, or both, either of which can be traced from the Colville River Bluffs basinward to the subsurface in the west-central North Slope. The Prince Creek fluvial deposits represent late Campanian to late Maastrichtian depositional environments that were affected by these base level changes influenced by tectonism, basin subsidence, and sea-level fluctuations.

  15. Depositional environments and processes in Upper Cretaceous nonmarine and marine sediments, Ocean Point dinosaur locality, North Slope, Alaska

    USGS Publications Warehouse

    Phillips, R.L.

    2003-01-01

    A 178-m-thick stratigraphic section exposed along the lower Colville River in northern Alaska, near Ocean Point, represents the uppermost part of a 1500 m Upper Cretaceous stratigraphic section. Strata exposed at Ocean Point are assigned to the Prince Creek and Schrader Bluff formations. Three major depositional environments are identified consisting, in ascending order, of floodplain, interdistributary-bay, and shallow-marine shelf. Nonmarine strata, comprising the lower 140 m of this section, consist of fluvial distributaries, overbank sediments, tephra beds, organic-rich beds, and vertebrate remains. Tephras yield isotopic ages between 68 and 72.9 Ma, generally consistent with paleontologic ages of late Campanian-Maastrichtian determined from dinosaur remains, pollen, foraminifers, and ostracodes. Meandering low-energy rivers on a low-gradient, low-relief floodplain carried a suspended-sediment load. The rivers formed multistoried channel deposits (channels to 10 m deep) as well as solitary channel deposits (channels 2-5 m deep). Extensive overbank deposits resulting from episodic flooding formed fining-upward strata on the floodplain. The fining-upward strata are interbedded with tephra and beds of organic-rich sediment. Vertical-accretion deposits containing abundant roots indicate a sheet flood origin for many beds. Vertebrate and nonmarine invertebrate fossils along with plant debris were locally concentrated in the floodplain sediment. Deciduous conifers as well as abundant wetland plants, such as ferns, horsetails, and mosses, covered the coastal plain. Dinosaur skeletal remains have been found concentrated in floodplain sediments in organic-rich bone beds and as isolated bones in fluvial channel deposits in at least nine separate horizons within a 100-m-thick interval. Arenaceous foraminifers in some organic-rich beds and shallow fluvial distributaries indicate a lower coastal plain environment with marginal marine (bay) influence. Marginal marine strata

  16. A compaction correction for the paleomagnetism of the Cretaceous Pigeon Point Formation of California

    NASA Astrophysics Data System (ADS)

    Kodama, K. P.; Davi, J. M.

    1995-10-01

    The paleomagnetism of the Cretaceous Pigeon Point Formation turbidites was reexamined to determine whether the 25° of southerly paleolatitudinal offset originally observed (Champion et al., 1984) for these rocks was all, or in part, due to compaction shallowing of their paleomagnetic inclination. The study consisted of two parts: (1) A standard paleomagnetic study, including detailed thermal and alternating field demagnetization, was conducted on oriented cores collected at Pigeon Point, approximately 50 km south of San Francisco, California. The results of this study were combined with the alternating field demagnetized results for samples provided by D. Champion from the initial Pigeon Point paleomagnetic study. The combined data set has a mean direction for Pigeon Point (I=41.6°, D=346.9°) similar to that originally obtained by Champion et al. (1984). (2) Material from the Pigeon Point Formation was disaggregated, given a laboratory analog of a postdepositional remanence, and compacted to pressures as high as 0.13 MPa which caused volume losses up to 53%. The laboratory-compacted samples were alternating field demagnetized, and their magnetic inclination and anisotropy of anhysteretic remanence were both measured. These data were used to derive correction curves, following Jackson et al. (1991), which describe the specific relationship between remanence anisotropy and inclination shallowing for the Pigeon Point Formation. Two correction curves were determined, one assuming that the magnetic particle orientation distribution experienced a prolate deformation after remanence acquisition and one assuming an oblate deformation. These two different corrections were necessary because the anisotropy of anhysteretic remanence indicates a composite fabric due to both a prelithification technically caused lineation and a burial compaction foliation. The anisotropy of anhysteretic remanence measured for each paleomagnetic sample and the correction curves determined from

  17. Late cretaceous foraminifera, paleoenvironments, and paleoceanography of the rosario formation, San Antonio del Mar, Baja California, Mexico

    USGS Publications Warehouse

    Maestas, Y.; MacLeod, K.G.; Douglas, R.; Self-Trail, J.; Ward, P.D.

    2003-01-01

    The 315 m of Rosario Formation exposed at the San Antonio del Mar (SADM) section (Baja California, Mexico) contains moderately-to-well preserved benthic and planktic foraminifera, calcareous nannofossils, and molluscs. Nannofossils suggest most of the SADM section was deposited within a narrow interval of the late Campanian (CC21-CC22), whereas foraminifera and molluscs suggest a younger maximum age (younger than the Globotruncana ventricosa Zone) and allow deposition over a longer interval of time. Planktic foraminifera at SADM represent common Tethyan taxa. They are largely restricted to the lower and middle portions of the section and comprise 0-???40% of foraminiferal assemblages. Stable isotopic analyses of Rugoglobigerina rugosa yield ??18OV-PDB values from -2.27%, to -2.82%, corresponding to salinity-corrected paleotemperature estimates of 26-30??C for the Late Cretaceous eastern Pacific. These estimates are as warm as modern tropical temperatures and are similar to tropical paleotemperature estimates from ??18O analyses of exceptionally preserved Maastrichtian samples; however, they are considerably warmer than most tropical Campanian-Maastrichtian estimates. Benthic foraminifera indicate outer shelf paleodepths with a slight increase in depth or decrease in benthic oxygen levels in the upper parts of the interval studied. The change in the benthic assemblage corresponds to an ???1??? positive shift in benthic ??O18, suggesting a relationship between benthic assemblages and an inferred increase in the local intensity of upwelling.

  18. Fossil birds from the Late Cretaceous Los Alamitos Formation, Río Negro Province, Argentina

    NASA Astrophysics Data System (ADS)

    Agnolin, Federico L.; Martinelli, Agustín G.

    2009-02-01

    In this note we report new avian remains from the Late Cretaceous Los Alamitos Formation (Campanian-Maastrichtian) at the Los Alamitos locality, Río Negro Province, Argentina. Isolated remains referable to indeterminate Aves, ?Patagopterygiformes, indeterminate Ornithurae, cf. Hesperornithes and cf. Neornithes are described and discussed. The new genus and species Alamitornis minutus is erected to include a minute-sized and gracile bird, probably related to the non-volant ratite-like bird Patagopteryx. If correctly identified, the record of Hesperornithes may be the first for this group in the Southern Hemisphere. The Los Alamitos paleoavifauna represents one of the most diverse fossil bird assemblage from the Mesozoic of Gondwana known to date.

  19. Dinosaur tracks from the Cedar Mountain Formation (Lower Cretaceous), Arches National Park, Utah

    USGS Publications Warehouse

    Lockley, M.G.; White, D.; Kirkland, J.; Santucci, V.

    2004-01-01

    The seventh and largest known dinosaur tracksite from the Cedar Mountain Formation is reported from two important stratigraphic levels in the Ruby Ranch Member within the boundaries of Arches National Park. Previous reports of sites with a few isolated tracks are of limited utility in indicating the fauna represented by track makers. The Arches site reveals evidence of several theropod morphotypes, including a possible match for the coelurosaur Nedcolbertia and an apparently didactyl Utahraptor-like dromeosaurid. Sauropod tracks indicate a wide-gauge morphotype (cf. Brontopodus). Ornithischian tracks suggest the presence of an iguandontid-like ornithopod and a large ankylosaur. Dinosaur track diversity is high in comparison with other early Cretaceous vertebrate ichnofaunas, and it correlates well with faunal lists derived from skeletal remains, thus providing a convincing census of the known fauna. ?? Taylor and Francis Inc.

  20. Factors controlling the abundance of organic sulfur in flash pyrolyzates of Upper Cretaceous kerogens from Sergipe Basin, Brazil

    USGS Publications Warehouse

    Carmo, A.M.; Stankiewicz, B.A.; Mastalerz, Maria; Pratt, L.M.

    1997-01-01

    The molecular and elemental composition of immature kerogens isolated from Upper Cretaceous marine carbonates from Sergipe Basin, Brazil were investigated using combined pyrolysis-gas chromatography/mass spectrometry and organic petrographic techniques. The kerogens are predominantly composed of reddish-fluorescing amorphous organic matter (AOM) and variable amounts of yellow-fluorescing alginite and liptodetrinite. The abundance of organic sulfur in the kerogens inferred from the ratio 2-ethyl-5-methylthiophene/(1,2-dimethylbenzene + dec-1-ene) in the pyrolyzates is variable and may be related to changes in the type of primary organic input and/or to variations in rates of bacterial sulfate reduction. A concomitant increase in S/C and O/C ratios determined in situ using the electron microprobe is observed in AOM and alginites and may be related to a progressive oxidation of the organic matter during sulfurization. The S/C ratio of the AOM is systematically higher than the S C ratio of the alginites. Combined with a thiophene distribution characteristic of pyrolyzates of Type II organic matter, the higher S/C of AOM in Sergipe kerogens suggests that sulfurization and incorporation of low-molecular weight lipids derived from normal marine organic matter into the kerogen structure predominated over direct sulfurization of highly aliphatic algal biomacromolecules.The molecular and elemental composition of immature kerogens isolated from Upper Cretaceous marine carbonates from Sergipe Basin, Brazil were investigated using combined pyrolysis-gas chromatography/mass spectrometry and organic petrographic techniques. The kerogens are predominantly composed of reddish-fluorescing amorphous organic matter (AOM) and variable amounts of yellow-fluorescing alginite and liptodetrinite. The abundance of organic sulfur in the kerogens inferred from the ratio 2-ethyl-5-methylthiophene/(1,2-dimethylbenzene+dec-1-ene) in the pyrolyzates is variable and may be related to changes in

  1. A multidisciplinary study of the Lower Cretaceous Cedar Mountain Formation, Mussentuchit Wash, Utah: a determination of the paleoenvironment and paleoecology of the Eolambia caroljonesa dinosaur quarry

    USGS Publications Warehouse

    Garrison, J.R.; Brinkman, D.; Nichols, D.J.; Layer, P.; Burge, D.; Thayn, D.

    2007-01-01

    A quarry within the Cedar Mountain Formation in Mussentuchit Wash, Emery County, Utah, produced a fossil assemblage containing the remains of at least eight juvenile iguanodontid dinosaurs (Eolambia caroljonesa). The Cedar Mountain Formation lies stratigraphically between the Tithonian-Berriasian (Upper Jurassic) Brushy Basin Member of the Morrison Formation and the Cenomanian (Upper Cretaceous) Dakota Formation. Detailed stratigraphic, sedimentological, geochronological, palynological, and paleontological data have been collected along a measured section at the site of the Cifelli #2 Eolambia caroljonesa Quarry. These data provide a chronostratigraphic and a biostratigraphic framework for the Cedar Mountain Formation and allow a detailed reconstruction of the paleoenvironment and the paleoecology of the local paleogeographic area from which E. caroljonesa have been recovered. Three 40Ar/39Ar ages ranging from 96.7 to 98.5 Ma have been obtained three stratigraphically distinct altered volcanic ash layers within the Mussentuchit Member, one of which passes through the E. caroljonesa quarry, that indicate that the quarry is latest Albian in age and that the stratigraphic boundary between the Mussentuchit Member of the Cedar Mountain Formation and the overlying Dakota Formation is at or near the Albian/Cenomanian boundary. Sedimentological and biostratigraphic data suggest that significant long-term and short-term climatic changes are recorded in the Cedar Mountain Formation. During deposition of the lower part of the formation, climatic conditions were warm and arid to semi-arid. During deposition of the upper part of the formation, conditions became more humid. The progressive change in climatic conditions was probably related to the transgression of the Mowry Sea from the north. Cyclic sedimentation in the Mussentuchit Member suggests high-frequency changes from wet to dry periods. ?? 2007 Elsevier Ltd. All rights reserved.

  2. Stratigraphic sequence, microfacies, and petroleum prospects of the Yamama Formation, Lower Cretaceous, southern Iraq

    SciTech Connect

    Sadooni, F.N. )

    1993-11-01

    The Lower Cretaceous Yamama Formation basin was deposited over two tectonic regimes, the northeastern flank of the stable Arabian platform and the unstable zone of the Mesopotamian foredeep. This situation and the probable syntectonic deposition of the formation over growing structures created complex carbonate lithologies. From this tectonic configuration and the facies distribution, it seems that the Yamama Formation was deposited in a setting that changes from an inner to an outer ramp. Along the hinge line separating those two tectonic units, oolite shoals developed. The crestal areas of the growing structures were occupied by stromatoporoid-sponge-coral reefs and oolitic facies. The areas between reefs were the sites of carbonate mud accumulation. For the purposes of regional correlation and reserve estimation, the Yamama Formation is divided into five lithologic units: three reservoir units, designated from top as YR-A, YR-B, and YR-C, separated by two permeability barrier units, YB-1 and YB-2. These reservoir units are thought to be at least partially isolated from each other. The best oil prospects are within the oolite shoals and the patch reef buildups in the crestal parts of the structures.

  3. Chapter 1: Executive Summary - 2003 Assessment of Undiscovered Oil and Gas Resources in the Upper Cretaceous Navarro and Taylor Groups, Western Gulf Province, Gulf Coast Region, Texas

    USGS Publications Warehouse

    ,

    2006-01-01

    The U.S. Geological Survey (USGS) recently completed an assessment of the undiscovered oil and gas potential of the Upper Cretaceous Navarro and Taylor Groups in the Western Gulf Province of the Gulf Coast region (fig. 1) as part of a national oil and gas assessment effort (USGS Navarro and Taylor Groups Assessment Team, 2004). The assessment of the petroleum potential of the Navarro and Taylor Groups was based on the general geologic elements used to define a total petroleum system (TPS), including hydrocarbon source rocks (source rock maturation, hydrocarbon generation and migration), reservoir rocks (sequence stratigraphy and petrophysical properties), and hydrocarbon traps (trap formation and timing). Using this geologic framework, the USGS defined five assessment units (AU) in the Navarro and Taylor Groups as parts of a single TPS, the Smackover-Austin-Eagle Ford Composite TPS: Travis Volcanic Mounds Oil AU, Uvalde Volcanic Mounds Gas and Oil AU, Navarro-Taylor Updip Oil and Gas AU, Navarro-Taylor Downdip Gas and Oil AU, and Navarro-Taylor Slope-Basin Gas AU (table 1).

  4. A condensed middle Cenomanian succession in the Dakota Sandstone (Upper Cretaceous), Sevilleta National Wildlife Refuge, Socorro County, New Mexico

    USGS Publications Warehouse

    Hook, Stephen C.; Cobban, William A.

    2007-01-01

    The upper part of the Dakota Sandstone exposed on the Sevilleta National Wildlife Refuge, northern Socorro County, New Mexico, is a condensed, Upper Cretaceous, marine succession spanning the first five middle Cenomanian ammonite zones of the U.S. Western Interior. Farther north in New Mexico these five ammonite zones occur over a stratigraphic interval more than an order of magnitude thicker. The basal part of this marine sequence was deposited in Seboyeta Bay, an elongate east-west embayment into New Mexico that marked the initial transgression of the western shoreline of the Late Cretaceous seaway into New Mexico. The primary mechanism for condensing this section was nearshore, submarine erosion, although nondeposition played a minor role. The ammonite fossils from each zone are generally fragments of internal molds that are corroded on one side, indicating submarine burial, erosion of the prefossilized steinkern, and corrosion on the sea floor. In addition, the base of the condensed succession is marked by a thin bed that contains abundant, white-weathering, spherical to cylindrical phosphate nodules, many of which contain a cylindrical axial cavity of unknown origin. The nodules lie on the bedding surface of the highly burrowed, ridge-forming sandstone near the top of the Dakota and occur in the overlying breccia. The breccia consists of rip-up clasts of sandstone and eroded internal molds of the ammonite Conlinoceras tarrantense, the zonal index for the basal middle Cenomanian. The nodules below the breccia imply a time of erosion followed by nondeposition or sediment bypass during which the phosphatization occurred. The breccia implies a time of submarine erosion, probably storm-related. Remarkably, this condensed succession and the basal part of the overlying Mancos Shale tongue contain one of the most complete middle Cenomanian ammonite sequences in the U.S. Western Interior. Five of the six ammonite zones that characterize the middle Cenomanian of the

  5. A condensed middle Cenomanian succession in the Dakota Sandstone (Upper Cretaceous), Sevilleta National Wildlife Refuge, Socorro County, New Mexico

    USGS Publications Warehouse

    Hook, S.C.; Cobban, W.A.

    2007-01-01

    The upper part of the Dakota Sandstone exposed on the Sevilleta National Wild-life Refuge, northern Socorro County, New Mexico, is a condensed, Upper Cretaceous, marine succession spanning the first five middle Cenomanian ammonite zones of the U.S. Western Interior. Farther north in New Mexico these five ammonite zones occur over a stratigraphic interval more than an order of magnitude thicker. The basal part of this marine sequence was deposited in Seboyeta Bay, an elongate east-west embayment into New Mexico that marked the initial transgression of the western shoreline of the Late Cretaceous seaway into New Mexico. The primary mechanism for condensing this section was nearshore, submarine erosion, although nondeposition played a minor role. The ammonite fossils from each zone are generally fragments of internal molds that are corroded on one side, indicating submarine burial, erosion of the prefossilized steinkern, and corrosion on the sea floor. In addition, the base of the condensed succession is marked by a thin bed that contains abundant, white-weathering, spherical to cylindrical phosphate nodules, many of which contain a cylindrical axial cavity of unknown origin. The nodules lie on the bedding surface of the highly burrowed, ridge-forming sand-stone near the top of the Dakota and occur in the overlying breccia. The breccia consists of rip-up clasts of sandstone and eroded internal molds of the ammonite Conlinoceras tarrantense, the zonal index for the basal middle Cenomanian. The nodules below the breccia. imply a time of erosion followed by nondeposition or sediment bypass during which the phosphatization occurred. The breccia implies a time of submarine erosion, probably storm-related. Remarkably, this condensed succession and the basal part of the overlying Mancos Shale tongue contain one of the most complete middle Cenomanian ammonite sequences in the U.S. Western Interior. Five of the six ammonite zones that characterize the middle Cenomanian of the

  6. Geohydrology and chemical quality of water in Middle and Upper Jurassic and Lower Cretaceous rocks, western Kansas

    USGS Publications Warehouse

    Kume, Jack

    1984-01-01

    Fresh and saline water occur in Upper Jurassic and Lower Cretaceous rocks in western Kansas. The maximum thickness of the Jurassic aquifer is about 50 feet. During 1981, water levels ranged from 255 to 1,160 feet below land surface; the static heads ranged from about 2,400 to 3,100 feet above sea level and the hydraulic gradient ranged from 16 feet per mile toward the northeast to 40 feet per mile toward the north. The water is moderately saline, very hard, a sodium sulfate or sodium chloride type, and unsuitable for drinking and irrigation. The maximum thickness of the Cheyenne aquifer is about 190 feet. During 1981, water levels ranged from 267 to 375 feet below land surface; the static heads varied from less than 2,300 to more than 3,200 feet above sea level; and the hydraulic gradient was 8 feet per mile toward the east. The water is fresh to moderately saline, soft to very hard, a sodium sulfate or sodium , bicarbonate type, and suitable to unsuitable for drinking and irrigation. The maximum thickness of the Dakota aquifer is about 150 feet. During 1982, water levels ranged from 24 to 604 feet below land surface; the static heads ranged from about 2,100 to 3,200 feet above sea level; and the hydraulic gradient was 11 feet per mile toward the east and northeast. The water is fresh to slightly saline, soft to very hard, and suitable to unsuitable for drinking and irrigation. (USGS)

  7. The genus Krithe (Ostracoda) from the Campanian and Maastrichtian (Upper Cretaceous) of the northern US Gulf Coastal Plain

    USGS Publications Warehouse

    Puckett, T.M.

    1997-01-01

    The ostracode genus Krithe is one of the most common genera in the Upper Cretaceous (late Santonian to Maastrichtian) deposits of the northern Gulf Coastal Plain of North America. Although it is never abundant, the genus occurs in sediments that were deposited under a wide range of palaeoenvironments, including nearshore sandy marls to offshore, nearly pure, chalk. The taxonomy of this taxon has been problematical, and what is herein considered to be a single species, K. cushmani, has been referred to in the literature under five different names. Two morphotypes were observed: relatively large individuals with 'mushroom'-shaped vestibules collected from chalk, and smaller individuals with pocket-shaped vestibules collected from nearshore deposits. Species of Krithe have been hypothesized to be useful in estimating dissolved oxygen concentration in ancient ocean floors, based on details of their morphology. Whereas the relationship between size and environment corroborates with previous predictions (larger individuals live in deeper water), the morphology of the vestibules contradicts predictions (the larger vestibules occur in the nearshore deposits and the smaller, more constricted vestibules occur in the chalk). A causal relationship between environment and morphology is discussed.

  8. Configuration of shelf sandstone oil reservoirs, Upper Cretaceous (Turonian) Turner Sandy member of Carlilie Shale, Powder River basin, Wyoming

    SciTech Connect

    Rice, D.D.; Keighin, C.W.

    1989-03-01

    Oil production in the Upper Cretaceous Turner Sandy Member of the Carlile shale on the east flank of the Powder River basin is established in two types of stratigraphic traps characterized by distinct geometries and reservoir properties. One type is medium-grained sandstone bodies as much as 4 m thick that have filled elongate (as much as 10 km), narrow (< 1.5 km), east-west-trending erosional depressions of low relief. Trough and tabular cross-stratification indicates an eastward direction of transport. This type of sandstone is interpreted as previously deposited sediments reworked by transgression following global drop in sea level in middle Turonian time. The sands were redistributed and concentrated by offshore-directed downwelling flows on inner shelf in irregularly spaced depressions controlled by recurrent movement of basement fault blocks. Although this type is limited in areal extent, reservoirs in it are good (porosity and permeability are as much as 20% and 100 md, respectively). In contrast, the other type of trap is generally very fine-grained sandstone that occurs in shoaling-upward sequences as much as 12 m thick. Shale intercalations decrease upward, and planar lamination and hummocky cross-stratification are prevalent. Upper parts of sequence are bioturbated and contain trace fossils of Skolithos ichnofacies. These sequences form widespread (70 km/sup 2/) bodies that were deposited below fair-weather base on the storm-wave-dominated outer shelf. Although the overall sandstone bodies are extensive and resulting production is large, reservoir in these bodies are characterized by thin beds and vertical and lateral discontinuity on a centimeter scale. In addition, sandstones are tight (average porosity and permeability are 15% and 0.5 md, respectively) because of original fine grain size and presence of authigenic clays.

  9. Isotope and elemental geochemistry of Cretaceous fossiliferous concretions (Santana Formation, Brazil)

    NASA Astrophysics Data System (ADS)

    Heimhofer, Ulrich; Meister, Patrick; Bernasconi, Stefano M.; Ariztegui, Daniel; Martill, David M.; Schwark, Lorenz

    2014-05-01

    Exceptional three-dimensional fossil preservation (incl. phosphatization of soft-tissues) within organic carbon-rich mudstones is often associated with the formation of a protective carbonate shell surrounding the fossil specimen. Examples for this type of preservation are the Early Cretaceous fishes, turtles and pterosaurs from the Brazilian Santana Formation. Numerous studies proposed different conceptual models for concretion formation. Having new state-of-the-art geochemical tools at hand we revisited these models for the Santana Formation as an exemplary case. Differential compaction clearly indicates early precipitation of micritic calcite surrounding a central cavity containing the still decomposing fossil. The presence of pyrite forming a circular rim around the fossil and carbonate with negative carbon isotope compositions suggest intense sulphate reduction whereby the production of ammonium from the decay of proteins led to an increased alkalinity, which induced early carbonate precipitation. By means of micro-XRF scanning we found that pyrite is absent from the interior part of the concretions and that total iron content is very low, which indicate absence of sulphate reduction at the center of the concretions and possibly local onset of methanogenesis. We postulate that the central cavity may even have been filled with methane gas that evolved from the decaying animal. Methane diffusing outward was anaerobically oxidized in the surrounding sulphate reduction zone. Carbonate clumped isotopes revealed that micritic calcite formed early, but that these early precipitates are overprinted by two different late diagenetic cements precipitated at elevated temperatures. The occurrence of an outermost "cone-in-cone" calcite rim can be associated with burial showing temperatures of up to 60°C. Strontium-isotope ratios of matrix calcite and cement phases show radiogenic values (0.710416 to 0.712465), which are significantly higher than typical marine Cretaceous

  10. Paleomagnetic data from Upper Cretaceous Red Beds, Northwest Vietnam (Song Da Terrane), and Their Bearing on the Extrusion History of Indochina and Deformation Along its Margins

    NASA Astrophysics Data System (ADS)

    Geissman, J. W.; Pho, N.; Burchfiel, B.; Muggleton, S. R.

    2008-12-01

    Northwest Vietnam mainly consists of the Song Da terrane, which is bounded to the east by the NW-oriented Ailao Shan/Red River (ASRR) fault system, interpreted to be the southwest margin of the South China Block, and the NW-oriented Song Ma fault. The northern termination of the Song Da terrane is considered to be where the NE-oriented, right lateral Dien Bien Phu fault intersects the ASRR. Whether the Song Da terrane is part of the extruded Indochina Block, paleomagnetic data from which suggest some 10°+ southward latitudinal displacement, can be evaluated with paleomagnetic data from rocks of the appropriate age. Our paleomagnetic sampling concentrated on the Upper Cretaceous Yen Chau Formation, which unconformably overlies Paleozoic and Triassic sedimentary rocks. The Yen Chau Formation is locally up to about 1300 m thick, and is characterized by medium to thick bedded, coarse to fine-grained sandstones and siltstones, all of which are partially cemented by hematite. Samples were collected from 10 localities using a portable drill, with 6 to 19 sites collected per locality, and 7 to 15 samples collected from each site. This approach allows evaluation of the integrity of the remanence at the locality level, where, presumably, considerable time is recorded in each section. Each locality is a homoclinal road cut exposure, with bedding dips varying from sub-horizontal to moderately overturned. NRM intensities range from about 0.7 mA/m to about 25 mA/m; values which are relatively low in comparison to many red beds. A varied response to alternating field (AF) demagnetization indicates that magnetite carries a considerable (over 50 percent) of the remanence; the finest grained samples of relatively high NRM intensity reveal little response to AF treatment, indicating a dominance by hematite, as also supported by three-component IRM thermal demagnetization. Samples with the highest NRM intensities and the least contribution by magnetite respond favorably to thermal

  11. New dinosaur fossils from ANA locality, Arcillas de Morella Formation (Aptian, Lower Cretaceous, Cinctorres, Spain)

    NASA Astrophysics Data System (ADS)

    Santos-Cubedo, A.; de Santisteban, C.; Suñer, M.; Galobart, A.

    2009-04-01

    Ana is one of the several dinosaur bone sites located in the Arcillas de Morella Formation (Aptian, Lower Cretaceous; eastern Iberian Chain, Spain). This site was discovered in 1998, but it remained unexcavated until 2002, when a palaeontologist team formed by members of the Institut Paleontología Miquel Crusafont from Sabadell and the Grup Guix from Vila-real unearthed the first fossil from the locality. Nowadays there are five hundred fossils collected, including vertebrate and invertebrate species. Dinosaur bones (Theropoda and Ornithopoda) are abundant in this assemblage and in the last field season bones determined as Sauropoda were found. Taxonomically, Ana is dominated by disarticulated remains of Ornithopoda, which are usually fragmentary and abraded. Many of the elements may have been reworked (spatial averaging and/or time averaging), and the fossil concentration constitutes an autochthonous to parautochthonous association, in a spatial sense. The remains found in the Ana fossils site are placed in sandstones and limes containing marine autochthonous fauna. These deposits were formed during the transgressive infilling of an incised valley. Sedimentological features indicate that fossils were finally deposited in starved shallow estuarine environment. Mineralogically, the sediment including the fossils contains grains of quartz, illite/mica, kaolinite/clorite, K-feldspar and plagioclase, distributed in two mainly grain populations, a silty-clay and a coarse sand size grain, indicating that the sediments were bedded in a low-medium energy depositional environment. Nowadays we identified in Ana, teeth of Theropoda indet. and Baryonychinae indet., and bones of Iguanodon sp. Herein, we report new fossil findings from Ana site. These materials have been determined as Iguanodontia, Titanosauriformes and Theropoda. These new findings will help to understand the dinosaur fauna present in the Lower Cretaceous of Els Ports (Castellón, Spain). Acknowledgments This

  12. Supercritical sheetflood deposits on the volcaniclastic alluvial fan: the Cretaceous upper Daeri Member, Wido Island, Korea

    NASA Astrophysics Data System (ADS)

    Gul Hwang, In; Gihm, Yong Sik; Kim, Min Cheol

    2016-04-01

    The upper Daeri Member is composed of subaerial primary and resedimented pyroclastic deposits. The upper Daeri Member accumulated under influence of tectonic subsidence, and the basin was divided into four blocks (Block 1 to 4) by intrabasinal normal faults (Fault A to C). Vertical separation of Fault B is estimated about 250 m and provided sufficient accommodation space on Block 3 with intrabasinal physiographic relief, resulting in conformable stacking of the upper Daeri Member on a volcaniclastic alluvial fan. The welded pumiceous lapilli tuff (primary one) was deposited by a pyroclastic density current during an explosive volcanic eruption. After the eruption, the resedimented pyroclastic deposits were deposited by episodic sediment gravity flows and are intercalated with the reddish, homogeneous mudstones. In Block 3 the resedimented pyroclastic deposits show an abrupt decrease in ten largest lithic clasts from within 3 km away from Fault B, reflecting rapid waning of parental sediment gravity flows. A wavy bedded lapilli tuff is one of the lithofacies of the resedimented pyroclastic deposits. The wavy bedded lapilli tuff is composed of symmetrical or nearly-symmetrical, wavy stratifications, forming undulatory bed geometry. The wavy stratifications are recognized by distinctive alternations of few cm to 10 cm thick, lapilli-rich and ash-rich layers. Beds of the wavy bedded lapilli tuff are 0.1 to 2 m thick (estimated in crests) and range in wavelength 1.3 m to 12 m (ave. 8 m). Both amplitude and wavelength gradually decrease away from Fault B. The wavy bedded lapilli tuff can laterally be traced over 90 m. Based on undulatory bed geometry and wavy stratifications, the wavy bedded lapilli tuff is interpreted as antidune bedforms, formed by supercritical sheetfloods. The symmetrical or nearly symmetrical wavy stratifications are due to maintenance of stationary state of standing waves of the sheetfloods. A down current decrease in both wavelength and thickness

  13. Sedimentology and Sequence Stratigraphy of the Lower Cretaceous Fortress Mountain and Torok Formations Exposed Along the Siksikpuk River, North-Central Alaska

    USGS Publications Warehouse

    Houseknecht, David W.; Schenk, Christopher J.; Wartes, Marwan A.

    2007-01-01

    An exposure of the Lower Cretaceous Fortress Mountain and Torok Formations along the Siksikpuk River in north-central Alaska provides a rare opportunity to observe the stratigraphic contact between these two formations and to interpret the depositional facies and sequence stratigraphy of the exposed strata. The Fortress Mountain Formation at the base of the measured section includes braided-fluvial and coastal-plain facies deposited in a lowstand-systems tract, and an overlying succession of mostly shallow marine facies deposited in the basal part of a transgressive-systems tract. The overlying Torok Formation includes a thick, upward-deepening succession of marine-shelf to marine-slope facies deposited in the upper part of the transgressive-systems tract. The upper part of the section includes marine-slope and incised-slope-channel turbidite deposits of the Torok Formation, interpreted as a highstand-systems tract. Consideration of the balance between accommodation and sediment flux inferred from the sequence-stratigraphic analysis suggests that both tectonics and eustasy may have influenced deposition of the lowstand-systems and transgressive-systems tracts. In contrast, the highstand-systems tract may have been primarily influenced by progradation of a regional sediment-dispersal system and by subsidence induced by sediment loading.

  14. Baja california: late cretaceous dinosaurs.

    PubMed

    Morris, W J

    1967-03-24

    Late Cretaceous dinosaurs have been discovered along the Pacific margin of Baja California. The presence of Hypacrosaurus sp. is suggestive of correlation with the Upper Edmonton Formation, Alberta. Dissimilarities between the Baja California fauna and those from contemporary units along the eastern trend of the Rocky Mountains suggest that Baja California was ecologically separated from mainland Mexico during late Campanian and early Maastrictian time. PMID:17830047

  15. Sedimentology and ichnology of shallow-water deltaic complex: lower Cretaceous Sparky Formation, Wainwright heavy oil pool, Alberta, Canada

    SciTech Connect

    Brodylo, L.A.

    1989-03-01

    Much of the 2.5 billion bbl of recoverable reserves in the Lloydminster heavy oil area lie within the Sparky Formation. In the Wainwright pool, the Sparky is 20-30 m thick and comprises three stacked parasequences interpreted to have formed during progradation of a shallow-water deltaic complex into the Cretaceous epicontinental Boreal Sea. Two 4 to 7 m-thick coarsening-upward parasequences comprise the lower Sparky member and are interpreted as progradational, brackish-water, delta lobe deposits. Intensely bioturbated prodelta mudstones grade up into delta-front siltstones/very fine sandstones, which contain low-angle stratification (HCS.), graded-laminated storm beds, and convex ripples, capped by abundant fair-weather wave ripples. Shoaling is reflected in the vertical succession of ichnofacies: Zoophycos(.)-Cruziana-Skolithos-Psilonichnus. Each parasequence is truncated by a flooding surface and overlain by a thin transgressive shale unit deposited within a bay following lobe abandonment. The 10 to 15 m-thick upper Sparky parasequence exhibits a complex three-dimensional arrangement of mudstones, siltstones, sandstones, and coals and is interpreted to have formed in a mosaic of bay, marsh, and swamp environments on the lower delta plain. Following abandonment of the entire deltaic complex, peat-forming environments were established resulting in the formation of a regionally extensive 2 to 3 m-thick coal seam that caps the Sparky succession. Delta-front sublitharenites were cleaned, sorted, and laterally redistributed by storm processes, and form better reservoir facies than feldspathic litharenites of the distributaries.

  16. Skull ecomorphology of megaherbivorous dinosaurs from the dinosaur park formation (upper campanian) of Alberta, Canada.

    PubMed

    Mallon, Jordan C; Anderson, Jason S

    2013-01-01

    Megaherbivorous dinosaur coexistence on the Late Cretaceous island continent of Laramidia has long puzzled researchers, owing to the mystery of how so many large herbivores (6-8 sympatric species, in many instances) could coexist on such a small (4-7 million km(2)) landmass. Various explanations have been put forth, one of which-dietary niche partitioning-forms the focus of this study. Here, we apply traditional morphometric methods to the skulls of megaherbivorous dinosaurs from the Dinosaur Park Formation (upper Campanian) of Alberta to infer the ecomorphology of these animals and to test the niche partitioning hypothesis. We find evidence for niche partitioning not only among contemporaneous ankylosaurs, ceratopsids, and hadrosaurids, but also within these clades at the family and subfamily levels. Consubfamilial ceratopsids and hadrosaurids differ insignificantly in their inferred ecomorphologies, which may explain why they rarely overlap stratigraphically: interspecific competition prevented their coexistence.

  17. Skull Ecomorphology of Megaherbivorous Dinosaurs from the Dinosaur Park Formation (Upper Campanian) of Alberta, Canada

    PubMed Central

    Mallon, Jordan C.; Anderson, Jason S.

    2013-01-01

    Megaherbivorous dinosaur coexistence on the Late Cretaceous island continent of Laramidia has long puzzled researchers, owing to the mystery of how so many large herbivores (6–8 sympatric species, in many instances) could coexist on such a small (4–7 million km2) landmass. Various explanations have been put forth, one of which–dietary niche partitioning–forms the focus of this study. Here, we apply traditional morphometric methods to the skulls of megaherbivorous dinosaurs from the Dinosaur Park Formation (upper Campanian) of Alberta to infer the ecomorphology of these animals and to test the niche partitioning hypothesis. We find evidence for niche partitioning not only among contemporaneous ankylosaurs, ceratopsids, and hadrosaurids, but also within these clades at the family and subfamily levels. Consubfamilial ceratopsids and hadrosaurids differ insignificantly in their inferred ecomorphologies, which may explain why they rarely overlap stratigraphically: interspecific competition prevented their coexistence. PMID:23874409

  18. A palynological biozonation for the uppermost Santonian and Campanian Stages (Upper Cretaceous) of South Carolina, USA

    USGS Publications Warehouse

    Christopher, R.A.; Prowell, D.C.

    2010-01-01

    Five palynological biozones are proposed for the uppermost Santonian and Campanian Stages of South Carolina. In ascending stratigraphic order, these highest-occurrence interval zones are the Osculapollis vestibulus (Ov) Biozone, the Holkopollenites propinquus (Hp) Biozone, the Holkopollenites forix (Hf) Biozone, the Complexiopollis abditus (Ca) Biozone, and the Osculapollis aequalis (Oa) Biozone. These biozones are based on an analysis of more than 400 subsurface and outcrop samples throughout the Coastal Plain Province of South Carolina, and the adjacent states of Georgia and North Carolina. Integration of the biostratigraphy with lithostratigraphy and geophysical log data suggests that the lower and upper boundaries of each biozone are bounded by regional unconformities. Five new species are described, and an emendation is presented for one additional species. ?? 2009 Elsevier Ltd.

  19. A palynological biozonation for the Maastrichtian Stage (Upper Cretaceous) of South Carolina, USA

    USGS Publications Warehouse

    Christopher, R.A.; Prowell, D.C.

    2002-01-01

    Three palynological biozones are proposed for the Maastrichtian Stage of South Carolina. In ascending stratigraphic order, the biozones are the Carolinapollis triangularis (Ct) Interval Biozone, the Holkopollenites chemardensis (Hc) Interval Biozone, and the Sparganiaceaepollenites uniformis (Su) Interval Biozone. Integration of the biostratigraphy with lithologic and geophysical log data suggests that within the study area, the upper and lower boundaries of each zone are bounded by regional unconformities, and that a three-fold subdivision of the Maastrichtian Stage is warranted. The biozonation is based on the analysis of 114 samples from 24 subsurface and three outcrop sections from the Coastal Plain of South Carolina; samples from an additional seven subsurface and 18 outcrop sections from North Carolina and Georgia were examined to evaluate the geographic extent of the biozones. One new genus and five new species of pollen are described, and emendations are presented for two genera and one species of pollen. ?? 2003 Published by Elsevier Science Ltd.

  20. Biostratigraphy, facies analysis of Upper Cretaceous-Lower Paleocene strata in south Zagros basin (southwestern Iran)

    NASA Astrophysics Data System (ADS)

    Afghah, Massih

    2016-07-01

    In this study, two stratigraphic sections of the Tarbur Formation named Kuh-e Gadvan and Kuh-e Tir were selected. The thicknesses of the whole sediments of the sections studied are about 1100 m of which 400 thin sections were studied. Two biozones are determined in Kuh-e Gadvan and three biozones are described in Kuh-e Tir section. According to established biozones, the age of Tarbur Formation of Kuh-e Gadvan section is assigned to Campanian-Maastrichtian and Tarbur Formation age determination shows relation to Maastrichtian-Lower Paleocene in Kuh-e Tir section. Seven major lithofacies are distinguished along two studied stratigraphic columns which are foraminifer-bioclast wackestone, algal-foraminifer- intraclast wackestone, rudist biclast wackestone, bioclast packstone, bioclast-intraclast grainstone, coral and rudist boundstone. According to the recognized lithofacies, paleoenvironment of the Tarbur formation consists of lagoon, open margin of the reef landward, margin of the reef, flat reef, and seaward margin of the reef. Comparison of studied sections allows that geologic setting had been controlled biostratigraphy and facies change.

  1. Biostratigraphy, facies analysis of Upper Cretaceous-Lower Paleocene strata in south Zagros basin (southwestern Iran)

    NASA Astrophysics Data System (ADS)

    Afghah, Massih

    2016-07-01

    In this study, two stratigraphic sections of the Tarbur Formation named Kuh-e Gadvan and Kuh-e Tir were selected. The thicknesses of the whole sediments of the sections studied are about 1100 m of which 400 thin sections were studied. Two biozones are determined in Kuh-e Gadvan and three biozones are described in Kuh-e Tir section. According to established biozones, the age of Tarbur Formation of Kuh-e Gadvan section is assigned to Campanian-Maastrichtian and Tarbur Formation age determination shows relation to Maastrichtian-Lower Paleocene in Kuh-e Tir section. Seven major lithofacies are distinguished along two studied stratigraphic columns which are foraminifer-bioclast wackestone, algal-foraminifer- intraclast wackestone, rudist biclast wackestone, bioclast packstone, bioclast-intraclast grainstone, coral and rudist boundstone. According to the recognized lithofacies, paleoenvironment of the Tarbur formation consists of lagoon, open margin of the reef landward, margin of the reef, flat reef, and seaward margin of the reef. Comparison of studied sections allows that geologic setting had been controlled biostratigraphy and facies change.

  2. Aggradation of gravels in tidally influenced fluvial systems: Upper Albian (Lower Cretaceous) on the cratonic margin of the North American Western Interior foreland basin

    USGS Publications Warehouse

    Brenner, Richard L.; Ludvigson, Greg A.; Witzke, B.L.; Phillips, P.L.; White, T.S.; Ufnar, David F.; Gonzalez, Luis A.; Joeckel, R.M.; Goettemoeller, A.; Shirk, B.R.

    2003-01-01

    Alluvial conglomerates were widely distributed around the margin of the Early Cretaceous North American Cretaceous Western Interior Seaway (KWIS). Conglomerates, sandstones, and lesser amounts of mudstones of the upper Albian Nishnabotna Member of the Dakota Formation were deposited as fill-in valleys that were incised up to 80 m into upper Paleozoic strata. These paleovalleys extended southwestward across present-day northwestern Iowa into eastern Nebraska. Conglomerate samples from four localities in western Iowa and eastern Nebraska consist mostly of polycrystalline quartz with lesser amounts of microcrystalline (mostly chert), and monocrystalline quartz. Previous studies discovered that some chert pebbles contain Ordovician-Pennsylvanian invertebrate fossils. The chert clasts analyzed in this study were consistent with these findings. In addition, we found that non-chert clasts consist of metaquartzite, strained monocrystalline quartz and 'vein' quartz from probable Proterozic sources, indicating that parts of the fluvial system's sediment load must have travelled distances of 400-1200 km. The relative tectonic stability of this subcontinent dictated that stream gradients were relatively low with estimates ranging from 0.3 to 0.6 m/km. Considering the complex sedimentologic relationships that must have been involved, the ability of low-gradient easterly-sourced rivers to entrain gravel clasts was primarily a function of paleodischarge rather than a function of steep gradients. Oxygen isotopic evidence from Albian sphaerosiderite-bearing paleosols in the Dakota Formation and correlative units from Kansas to Alaska suggest that mid-latitude continental rainfall in the Albian was perhaps twice that of the modern climate system. Hydrologic fluxes may have been related to wet-dry climatic cycles on decade or longer scales that could account for the required water supply flux. Regardless of temporal scale, gravels were transported during 'high-energy' pulses, under

  3. Sedimentation and diagenesis along open and island-protected windward carbonate platform margins of the Cretaceous El Abra Formation, Mexico

    NASA Astrophysics Data System (ADS)

    Minero, Charles J.

    1991-05-01

    The windward margin of the mid-Cretaceous Valles-San Luis Potosi carbonate platform in northeastern Mexico included open and island-protected segments. Depositional environments and diagenesis vary markedly with margin type. Sand shoals near the windward open margin are composed of oncoid-bioclastic and cross-laminated carbonates. Increasingly restricted and finer lagoonal and tidal-flat environments occurred bankwards, recording gradually decreasing wave and current energy. Lithofacies include peloid-miliolid, cryptalgal laminite, lime mudstone, and molluscan carbonates. Islands along the windward margin are composed of rudistid-skeletal debris from adjacent reefs. Lagoonal to tidal-flat sediments were deposited bankwards. Similar lithofacies occur as in these environments along the open margin but they are muddier and contain less diverse fauna. The different energy regimes along the margin influenced the distribution and packaging of banktop sediments. The bankward transition to low-energy, restricted environments was gradual across the open margin. In contrast, muddy sediments with restricted fauna accumulated in close proximity to the island-protected margin. Non-cyclic vertical lithofacies successions characterized the open platform margin, whereas asymmetric shoaling-upward sequences characterized the island-protected margin. Early diagenesis along the open margin was minor; burial diagenesis was of major importance. Thin rinds of marine cement are widespread but meteoric diagenesis was minor. Burial promoted extensive compaction. Mg-rich connate brines expressed from Guaxcama gypsum resulted in dolomitization and lithification, thereby precluding further compaction. Pore fluids resulting from dehydration of Guaxcama gypsum to anhydrite yielded pore-filling and replacement anhydrite in the El Abra Formation. Burial and Laramide deformation (Maastrichtian-Paleocene) resulted in stylolitization and extensive fracturing. Uplift produced widespread meteoric

  4. Sedimentary features of the Blackhawk formation (Cretaceous) at Sunnyside, Carbon County, Utah

    USGS Publications Warehouse

    Maberry, John O.

    1968-01-01

    The Blackhawk Formation at Sunnyside, Utah, was deposited along the western margin of the Western Interior Cretaceous sea during southeastward withdrawal of the sea. Sand was the dominant type of land-derived sediment deposited in the Sunnyside district during the regressive phases. Sand bodies prograded seaward in response to changing sediment supply from a source west of Sunnyside. Where conditions were favorable for the accumulation of vegetable material, peat deposits formed and were later changed to bituminous Coal by diagenesis. Studies of the coal bed show that the coals were formed from accumulation of small, low-growing plants and plant debris that was transported into the area of accumulation. Remains of large plants in the coals are rare. Trace fossils, which are tracks, trails and burrows formed by organisms and preserved in the rock, are extremely abundant in the Blackhawk rocks. These biogenic sedimentary structures are common in Cretaceous deposits throughout the western United States. Trace fossil distribution in the rocks is controlled by the depositional environment preferred by their creators. A study of the trace fossils of a. locality allows a more precise determination of the conditions during deposition of the sediments. Water depth, bottom conditions, salinity, current velocity and amount of suspended nutrients in the water are some of the environmental factors that may be reconstructed by studying trace fossils. The Blackhawk Formation at Sunnyside comprises the members, the Kenilworth Member and the Sunnyside Member. Field studies show that the formation may be further subdivided in the Sunnyside district., according to the precepts of units of mappable thickness and similar lithologic characteristics. The Blackhawk pinches out eastward and north. ward into the Mancos Shale, and names for submembers become meaningless. Names are of value in the region of interest, however, because of the prominence of the named units. Coal mining is the

  5. A new angiosperm from the Crato Formation (Araripe Basin, Brazil) and comments on the Early Cretaceous monocotyledons.

    PubMed

    De Lima, Flaviana J; Saraiva, Antônio A F; Da Silva, Maria A P; Bantim, Renan A M; Sayão, Juliana M

    2014-12-01

    The Crato Formation paleoflora is one of the few equatorial floras of the Early Cretaceous. It is diverse, with many angiosperms, especially representatives of the clades magnoliids, monocotyledons and eudicots, which confirms the assumption that angiosperm diversity during the last part of the Early Cretaceous was reasonably high. The morphology of a new fossil monocot is studied and compared to all other Smilacaceae genus, especially in the venation. Cratosmilax jacksoni gen. et sp. nov. can be related to the Smilacaceae family, becoming the oldest record of the family so far. Cratosmilax jacksoni is a single mesophilic leaf with entire margins, ovate shape, with acute apex and base, four venation orders and main acrodromous veins. It is the first terrestrial monocot described for the Crato Formation, monocots were previously described for the same formation, and are considered aquatics. Cratosmilax jacksoni is the first fossil record of Smilacaceae in Brazil, and the oldest record of this family.

  6. Fluvial architecture of dinosaur bonebeds in the Cretaceous Judith River Formation, south-central Montana

    SciTech Connect

    Wilson, K.M. ); Dodson, P. ); Fiorillo, A.R. )

    1991-03-01

    Fluvial architecture of dinosaur bonebeds in the Cretaceous Judith River Formation, south-central Montana, has been the subject of intensive paleontological study for many years. However, little has been published on the sedimentology of the formation in this area. The authors have completed a preliminary field study of fluvial facies, with a view towards correcting this omission. Initial results include detailed facies descriptions and maps for five quarries along a line of transect stretching some 40 km parallel to depositional dip. Facies identified are predominantly overbank splays and levees, with common point bar/alluvial channel units and occasional small, possibly estuarine sand bodies in parts of the section. Shell beds (mainly oysters) and bedded, 1 m thick coals are also significant in some sections. Preliminary attempts at paleohydrology suggest river channels in some parts of the section were about 100 m wide and 2 m deep; however, other parts of the section exhibit much larger channel widths. Channel stacking is common. Preliminary results suggest a strong correlation between the occurrence of reddish brown carbonaceous silty shales, and dinosaur bone deposits.

  7. Geology and sequence stratigraphy of undiscovered oil and gas resources in conventional and continuous petroleum systems in the Upper Cretaceous Eagle Ford Group and related strata, U.S. Gulf Coast Region

    USGS Publications Warehouse

    Dubiel, Russell F.; Pearson, Ofori N.; Pitman, Janet K.; Pearson, Krystal M.; Kinney, Scott A.

    2012-01-01

    The U.S. Geological Survey (USGS) recently assessed the technically recoverable undiscovered oil and gas onshore and in State waters of the Gulf Coast region of the United States. The USGS defined three assessment units (AUs) with potential undiscovered conventional and continuous oil and gas resources in Upper Cretaceous (Cenomanian to Turonian) strata of the Eagle Ford Group and correlative rocks. The assessment is based on geologic elements of a total petroleum system, including hydrocarbon source rocks (source rock maturation, hydrocarbon generation and migration), reservoir rocks (sequence stratigraphy and petrophysical properties), and traps (formation, timing, and seals). Conventional oil and gas undiscovered resources are in updip sandstone reservoirs in the Upper Cretaceous Tuscaloosa and Woodbine Formations (or Groups) in Louisiana and Texas, respectively, whereas continuous oil and continuous gas undiscovered resources reside in the middip and downdip Upper Cretaceous Eagle Ford Shale in Texas and the Tuscaloosa marine shale in Louisiana. Conventional resources in the Tuscaloosa and Woodbine are included in the Eagle Ford Updip Sandstone Oil and Gas AU, in an area where the Eagle Ford Shale and Tuscaloosa marine shale display vitrinite reflectance (Ro) values less than 0.6%. The continuous Eagle Ford Shale Oil AU lies generally south of the conventional AU, is primarily updip of the Lower Cretaceous shelf edge, and is defined by thermal maturity values within shales of the Eagle Ford and Tuscaloosa that range from 0.6 to 1.2% Ro. Similarly, the Eagle Ford Shale Gas AU is defined downdip of the shelf edge where source rocks have Ro values greater than 1.2%. For undiscovered oil and gas resources, the USGS assessed means of: 1) 141 million barrels of oil (MMBO), 502 billion cubic feet of natural gas (BCFG), and 4 million barrels of natural gas liquids (MMBNGL) in the Eagle Ford Updip Sandstone Oil and Gas AU; 2) 853 MMBO, 1707 BCFG, and 34 MMBNGL in the

  8. Submarine fan facies of Upper Cretaceous Strata, Southern San Rafael Mountains, Santa Barbara County, California

    SciTech Connect

    Toyne, C.D.

    1986-04-01

    A 2900-m thick Campanian-Maestrichtian(.) turbidite sequence in Upper Mono Creek Canyon is interpreted to be a progradational submarine fan complex comprised of outer fan, middle fan, inner fan, and slope facies. The basal 600 m of the section consists of thinly bedded, laterally continuous fine sandstones, siltstones, and mudstones (mainly Mutti and Ricci Lucci facies D), interpreted to be outer fan interlobe and lobe-fringe deposits. These are punctuated by infrequent medium to very thickly bedded, flat-based, fine to coarse sandstones (facies C and B), which commonly coarsen and thicken upward, and are interpreted to be depositional lobes. Overlying these deposits are approximately 1400 m of middle fan deposits composed of frequent lenticular, commonly channelized and amalgamated, thickly bedded, fine to very coarse sandstones (facies C and B) organized in fining- and thinning-upward sequences, interpreted to be braided-channel deposits. These alternate with less common nonchannelized coarsening- and thickening-upward sequences suggestive of lobe-apical cycles. These multistory sand deposits are nested within thick intervals of fine sandstones, siltstones, and mudstones (facies C and D), interpreted to be levee, crevasse-splay, and interchannel deposits. Interfingered with and overlying these deposits are approximately 500 m of fining- and thinning-upward or noncyclic, erosionally based, commonly amalgamated, very thickly bedded, medium to very coarse sandstones, pebbly sandstones, and conglomerates (facies A and B), interpreted to be inner fan deposits. Intercalated within this facies, infrequent, laterally discontinuous, thin to thickly bedded, fine to coarse sandstones, siltstones, and mudstones exist, interpreted to be interchannel, levee, and possibly channel-fill deposits.

  9. U-Pb geochronology and geochemistry of the McCoy Mountains Formation, southeastern California: A Cretaceous retroarc foreland basin

    USGS Publications Warehouse

    Barth, A.P.; Wooden, J.L.; Jacobson, C.E.; Probst, K.

    2004-01-01

    The timing of deposition of fluvial sediments now forming the >7-km-thick McCoy Mountains Formation is one of the key uncertainties in reconstructing the Mesozoic poleogeography of southern California and western Arizona. Ion-microprobe U-Pb geochronologic data for individual zircons from nine sandstones from the McCoy Mountains type section and six associated igneous rocks provide significant new constraints on the tectonic setting and the timing of deposition within the northwest-trending McCoy basin. U-Pb zircon data from a metavolcanic rock of the underlying Dome Rock sequence in the Palen Mountains confirm that the McCoy Mountains Formation was deposited after regional Middle to Late Jurassic arc magmatism. U-Ph zircon data from a Late Cretaceous granodiorite intruding the formation in the Coxcomb Mountains confirm that the formation was deformed and metamorphosed prior to 73.5 ?? 1.3 Ma. Populations of detrital zircons vary systematically with both rock type and stratigraphic height; lithic arkoses predominantly derived from the west have consistently more abundant younger zircons than do litharenite sandstones predominantly derived from the north, and the youngest zircons yield maximum depositional ages that decrease from 116 Ma near the base to 84 Ma near the top of the section. The detrital-zircon data permit a Late Jurassic age for the basal, comparatively quartz-rich sandstone. However, the data further suggest that >90% of the formation was deposited between middle Early and middle Late Cretaceous time. These results are consistent with the hypothesis that most of the McCoy Mountains Formation represents a retroarc foreland basin, deposited behind the active, evolving Cretaceous Cordilleran continental-margin magmatic arc that lay to the west and in the foreland of the actively deforming Cretaceous Maria fold-and-thrust belt.

  10. Upper Cretaceous and lower Paleogene benthic foraminiferal paleoecology from north-eastern Tunisia: El Melah section

    NASA Astrophysics Data System (ADS)

    Gallala, N.; Zaghbib-Turki, D.; Turki, M. M.; Arenillas, I.; Arz, J. A.; Molina, E.

    2009-04-01

    As an impact of the bolide and ejecta falls at the K/Pg boundary the planktonic Foraminifera have suffered sever mass extinction. However, no small Benthic Foraminifera species mass extinction at the K/Pg boundary has documented. Nevertheless many species have showed disturbance. The Maastrichtian assemblages may be different from those of the lower Paleogene by their species content, diversity and frequencies. At the El Melah section, the small benthic foraminifera indicate upper bathyal environment, and manifest significant faunal turnover. Until the uppermost Maastrichtian, their assemblages are highly diversified, with 109 species. They are dominated by endobenthic morphotypes (72 %). At the K/Pg boundary, although 34% of them seem to disappear, but only few species have really extinct such us Arenobulimina obesa. Nevertheless, the majority of species persist elsewhere at the Danian (e.g. Gaudryina aissana, Gaudryina inflata, Tritaxia midwayensis, Coryphostoma incrassata). At the lower Danian, the survivor Maastrichtian species are of 66%. Some of them disappeared temporary. Three survivor species were eclipsed during the Guembelitria cretacea zone (Globobulimina ovata, Praebulimina carseyae and Anomalinoides welleri) and 27 other species were diminished during the Parvularugoglobigerina eugubina subzone. They are composed of both calcareous fauna (e.g. Bulimina rugifera, Bolivina deccurens, Anomalinoides midwayensis, Dentalina colei, Marginulina cf. glabra) and agglutinated fauna (e.g. Spiroplectamina knebeli and Saccamina placenta). Throughout the Parasubbotina pseudobulloides subzone, 15 others species were progressively disappeared. They are oligotrophic and low oxygen tolerant. About the Masstrichtian species Gaudryina inflata, G. pyramidata and Tritaxia midwayensis. These species seem to be more trophic exigent.Besides, at the lower Danian, 27 species seems to be appeared. Few of them appeared really (e.g. Spiroplectamina dentata, Dentalina vertebralis

  11. An exquisitely preserved troodontid theropod with new information on the palatal structure from the Upper Cretaceous of Mongolia

    NASA Astrophysics Data System (ADS)

    Tsuihiji, Takanobu; Barsbold, Rinchen; Watabe, Mahito; Tsogtbaatar, Khishigjav; Chinzorig, Tsogtbaatar; Fujiyama, Yoshito; Suzuki, Shigeru

    2014-02-01

    Troodontidae is a clade of small-bodied theropod dinosaurs. A new troodontid, Gobivenator mongoliensis gen. et sp. nov., is described based on the most complete skeleton of a Late Cretaceous member of this clade presently known, from the Campanian Djadokhta Formation in the central Gobi Desert. G. mongoliensis is different from other troodontids in possessing a pointed anterior end of the fused parietal and a fossa on the surangular in front of the posterior surangular foramen. The skull was superbly preserved in the specimen and provides detailed information of the entire configuration of the palate in Troodontidae. Overall morphology of the palate in Gobivenator resembles those of dromaeosaurids and Archaeopteryx, showing an apparent trend of elongation of the pterygoid process of the palatine and reduction of the pterygopalatine suture toward the basal Avialae. The palatal configuration suggests that the skull of Gobivenator would have been akinetic but had already acquired prerequisites for later evolution of cranial kinesis in birds, such as the loss of the epipterygoid and reduction in contact areas among bones.

  12. Relationship of sea level changes and intrabasinal tectonics on upper Cretaceous depositional sequences, Tremp basin, Pyrenees, Spain

    SciTech Connect

    Simo, A.

    1988-02-01

    Well-exposed Upper Cretaceous rocks in the Tremp basin display the effects of subsidence and sea level changes. Subsidence and a net sea level rise control the sequence geometry and the cyclicity of transgressive-regressive units. In addition, subsidence, sea level, and sediment supply control the facies framework. The Tremp basin, where specific depositional processes can be related to basin evolution, is proposed as a reference section to compare tectonism vs. sea level changes. Five depositional sequences recognized are seismic-stratigraphic in scale and are correlatives of global rhythms. Sequences are separated by unconformable or correlative conformable surfaces. Most of the surfaces in the area are concordant, characterized by a sharp transition upward from shallower to deeper facies. Sea level drops exposed the inner shelf but not the shelf margin; they did, however, result in submarine erosion and basin-restricted wedge deposition. The three oldest sequences are carbonate-rich. Each sequence exhibits very little coastal onlap; however, each successively younger carbonate platform backsteps the former. Thermal subsidence (6.3 cm/1000 yr) created depositional space in the basin, and uplift reduced shelf onlap. The fourth sequence is carbonate-rich on the shelf and siliciclastic-rich in the basin. Subsidence first increased (shelf = 5.13 cm/1000 yr; basin = 15.4 cm/1000 yr) because of thrusting west of the area, resulting in coastal onlap over 60 km and accompanying backstepping of the carbonate platform. Subsidence later decreased, resulting in platform progradation. The fifth depositional sequence shows an overall siliciclastic regression, in response to regional thrusting and uplift.

  13. Relationship of sea level changes and intrabasinal tectonics on Upper Cretaceous depositional sequences, Tremp Basin, Pyrenees, Spain

    SciTech Connect

    Simo, A.

    1988-01-01

    Well-exposed Upper Cretaceous rocks in the Tremp basin display the effects of subsidence and sea level changes. Subsidence and a net sea level rise control the sequence geometry and the cyclicity of transgressive-regressive units. In addition, subsidence, sea level, and sediment supply control the facies framework. The Tremp basin, where specific depositional processes can be related to basin evolution, is proposed as a reference section to compare tectonism vs. sea level changes. Five depositional sequences recognized are seismic-stratigraphic in scale and are correlatives of global rhythms. Sequences are separated by uncomfortable or correlative conformable surfaces. Most of the surfaces in the area are concordant, characterized by a sharp transition upward from shallower to deeper facies. Sea level drops exposed the inner shelf but not the shelf margin; they did, however, result in submarine erosion and basin-restricted wedge deposition. The three oldest sequences are carbonate-rich. Each sequence exhibits very little coastal onlap; however, each successively younger carbonate platform backsteps the former. Thermal subsidence (6.3cm/1,000 yr) created depositional space space in the basin, and uplift reduced shelf onlap. The fourth sequence is carbonate-rich on the shelf and siliciclastic-rich in the basin. Subsidence first increased (shelf = 5.13 cm/1,000 yr; basin = 15/4 cm/1,000 yr) because of thrusting west of the area, resulting in coastal onlap over 60 km and accompanying backstepping of the carbonate platform. Subsidence later decreased, resulting in platform progradation. The fifth depositional sequence shows an overall siliciclastic regression, in response to regional thrusting and uplift.

  14. A Basal Tapejarine (Pterosauria; Pterodactyloidea; Tapejaridae) from the Crato Formation, Early Cretaceous of Brazil

    PubMed Central

    Leal, Maria Eduarda de Castro; Kellner, Alexander Wilhelm Armin

    2016-01-01

    A three-dimensional and almost complete pterosaur mandible from the Crato Formation (Early Cretaceous of Northeastern Brazil), Araripe Basin, is described as a new species of a tapejarine tapejarid. Tapejarines are a particular group of toothless pterosaurs, characterized by well-developed cranial crests, downturned rostra, and have been proposed to represent frugivorous flying reptiles. Though comparatively well represented and distributed, the evolutionary history of the group is still poorly known, and the internal relationships of its members are not well understood. The new species here reported, named Aymberedactylus cearensis gen. et sp. nov., adds new data concerning the evolution of the group, concerning their morphology and geographical origin. It differs from known tapejarids due to its unusually elongate retroarticular process and a shallow fossa on the splenial exhibiting distinctive rugose texture. Furthermore, it exhibits a suite of basal and derived conditions within the Tapejaridae, demonstrating how their morphological traits probably evolved and that these forms were even more diverse than already acknowledged. The discovery of Aymberedactylus cearensis sheds new light on the evolutionary history of the Tapejarinae. PMID:27655346

  15. The first dromaeosaurid (Dinosauria: Theropoda) from the Lower Cretaceous Bayan Gobi Formation of Nei Mongol, China.

    PubMed

    Pittman, Michael; Pei, Rui; Tan, Qingwei; Xu, Xing

    2015-01-01

    The first dromaeosaurid theropod from the Lower Cretaceous Bayan Gobi Formation is identified based on an incompletely preserved partially-articulated left leg, increasing the known diversity of its understudied ecosystem. The leg belongs to specimen IVPP V22530 and includes a typical deinonychosaurian pedal phalanx II-2 with a distinct constriction between the enlarged proximal end and the distal condyle as well as a typical deinonychosaurian enlarged pedal phalanx II-3. It possesses a symmetric metatarsus and a slender and long MT V that together suggest it is a dromaeosaurid. Two anatomical traits suggest the leg is microraptorine-like, but a more precise taxonomic referral was not possible: metatarsals II, III and IV are closely appressed distally and the ventral margin of the medial ligament pit of phalanx II-2 is close to the centre of the rounded distal condyle. This taxonomic status invites future efforts to discover additional specimens at the study locality because-whether it is a microraptorine or a close relative-this animal is expected to make important contributions to our understanding of dromaeosaurid evolution and biology. IVPP V22530 also comprises of an isolated dromaeosaurid manual ungual, a proximal portion of a right theropod anterior dorsal rib and an indeterminate bone mass that includes a collection of ribs. Neither the rib fragment nor the bone mass can be confidently referred to Dromaeosauridae, although they may very well belong to the same individual to whom the left leg belongs. PMID:26664809

  16. The first dromaeosaurid (Dinosauria: Theropoda) from the Lower Cretaceous Bayan Gobi Formation of Nei Mongol, China

    PubMed Central

    Pei, Rui; Tan, Qingwei; Xu, Xing

    2015-01-01

    The first dromaeosaurid theropod from the Lower Cretaceous Bayan Gobi Formation is identified based on an incompletely preserved partially-articulated left leg, increasing the known diversity of its understudied ecosystem. The leg belongs to specimen IVPP V22530 and includes a typical deinonychosaurian pedal phalanx II-2 with a distinct constriction between the enlarged proximal end and the distal condyle as well as a typical deinonychosaurian enlarged pedal phalanx II-3. It possesses a symmetric metatarsus and a slender and long MT V that together suggest it is a dromaeosaurid. Two anatomical traits suggest the leg is microraptorine-like, but a more precise taxonomic referral was not possible: metatarsals II, III and IV are closely appressed distally and the ventral margin of the medial ligament pit of phalanx II-2 is close to the centre of the rounded distal condyle. This taxonomic status invites future efforts to discover additional specimens at the study locality because—whether it is a microraptorine or a close relative—this animal is expected to make important contributions to our understanding of dromaeosaurid evolution and biology. IVPP V22530 also comprises of an isolated dromaeosaurid manual ungual, a proximal portion of a right theropod anterior dorsal rib and an indeterminate bone mass that includes a collection of ribs. Neither the rib fragment nor the bone mass can be confidently referred to Dromaeosauridae, although they may very well belong to the same individual to whom the left leg belongs. PMID:26664809

  17. Detrital and delayed CRM acquisition in redbeds: the Lower Cretaceous Zicapa Formation, southern Mexico

    NASA Astrophysics Data System (ADS)

    Sierra-Rojas, M. I.; Molina-Garza, R. S.

    2013-05-01

    The Lower Cretaceous Zicapa Formation is characterized by hematite-cemented clastic rocks interbeded with limestone and volcanic rocks, deposited in continental to transitional-marine environments. The paleomagnetic data presented here correspond to exposures in the San Juan de las Joyas locality, in the Mixteca terrain of southern Mexico. Hematite cement is derived from an important input of primary volcanic material contemporaneous with deposition and from mafic to intermediate metavolcanic sources. We sampled 17 sites in a 110 m segment of continuous depositation of fine to coarse, red to purple, lithic sandstone and siltstone. The natural magnetization is multivectorial, and AF demagnetization suggests that it resides primarily in hematite. One magnetization component is unblocked below 200C is north-directed and positive. A low-unblocking temperature magnetization (LT) is unblocked between 250-500C, and a high-unblocking-temperature component (HT) is defined between about 600-650C. Both, the LT and HT components are dual-polarity and form nearly antipodal groups of WNW (ESE) directions. NRM demagnetization and rock magnetic data suggest the presence of two kinds of particles carrying the LT and HT components. Polarity changes in the section sampled are characterized by sites that register in the HT component the magnetic field previous to the transition of polarity (which is detrital magnetization residing in specular hematite), whilst the LT registers the magnetic field after the polarity transition. Typically, in the overlying (post-transition) site the LT and HT components are of the same polarity. This suggests that the LT component is a late (or delayed) CRM that resides in small particles of pigmentary hematite. The accepted sites yield a tilt corrected mean of declination Dec= 273 degrees, inclination Inc= 33.1 degrees (α95=11.7 y k=18).The mean directions are discordant with respect to expected North America reference for Early Cretaceous indicating a

  18. Sedimentary facies and diagenetic features of the Early Cretaceous Fahliyan Formation in the Zagros Fold-Thrust Belt, Iran

    NASA Astrophysics Data System (ADS)

    Sahraeyan, Mohammad; Bahrami, Mohammad; Hooshmand, Mohammad; Ghazi, Shahid; Al-Juboury, Ali Ismail

    2013-11-01

    The Early Cretaceous Fahliyan Formation (middle part of the Khami Group), is one of the important reservoir rocks in the Zagros Fold-Thrust Belt. The Zagros Fold-Thrust Belt is located on the boundary between the Arabian and Eurasian lithospheric plates and formed from collision between Eurasia and advancing Arabia during the Cenozoic. In this study area, the Fahliyan Formation with a thickness of 325 m, consists of carbonate rocks (limestone and dolomite). This formation overlies the Late Jurassic Surmeh Formation unconformably and underlies the Early Cretaceous Gadvan Formation conformably at Gadvan Anticline. The formation was investigated by a detailed petrographic analysis to clarify the depositional facies, sedimentary environments and diagenetic features in the Gadvan Anticline. Petrographic studies led to recognition of the 12 microfacies that were deposited in four facies belts: tidal flat, lagoon, and shoal in inner ramp and shallow open marine in mid-ramp environments. The absence of turbidite deposits, reefal facies, and gradual facies changes show that the Fahliyan Formation was deposited on a carbonate ramp. Calcareous algae and benthic foraminifera are abundant in the shallow marine carbonates of the Fahliyan Formation. The diagenetic settings favored productioning a variety of features which include cements from early to late marine cements, micritization, dolomitization, compaction features, dissolution fabric, and pores. The diagenetic sequence can be roughly divided into three stages: (1) eugenic stage: marine diagenetic environment, (2) mesogenic stage: burial environment, and (3) telogenic stage: meteoric diagenetic environment.

  19. Integrated biostratigraphy, stage boundaries and Paleoclimatology of the Upper Cretaceous-Lower Eocene successions in Kharga and Dakhala Oases, Western Desert, Egypt

    NASA Astrophysics Data System (ADS)

    Khalil, H.; Al Sawy, S.

    2014-08-01

    The Upper Cretaceous-Lower Eocene succession in the studied sections is divided into four rock units that arranged from base to top: the Dakhla, Tarawan, Esna and the Thebes formations. Detailed study of the foraminifera and calcareous nannofossils has led to the recognition of 58 and 82 species, respectively. Based on planktonic foraminifera and calcareous nannofossils 8 planktonic foraminiferal biozones (CF4, P2, P3, P4, E1, E2, E3 and E4) have been recognized as well as 8 calcareous nannofossil biozones (CC25b, NP3, NP4, NP5, NP6, NP7/8, NP9, and NP10). At Gabal Teir/Tarawan section, Kharga Oasis, the Paleocene can be divided into three stages; Danian, Selandian and Thanetian. The Danian/Selandian boundary is placed at P3a/P3b zonal boundary (LO of Igorina albeari) which corresponds to the level of LO of Lithoptychius ulii, Fasciculithus pileatus, Fasciculithus involutus and Lithoptychius janii (upper part of Zone NP4). The Selandian/Thanetian boundary, on the other hand, can be traced within the foraminiferal Zone P4 (Globanomalina pseudomenardii Zone) and between the nannofossil zones NP6 and NP7/8 (LO of Discoaster mohleri). At Gabal Ghanima section, the Paleocene/Eocene boundary is located within the lower part of the Esna Formation. It can be traced at the base of planktonic foraminiferal Zone E1 (LOs of Acarinina africana, A sibaiyaensis and Morozovella allinsoensis), and at the NP9a/NP9b subzonal boundary (LO of Rhomboaster spp). However, the lower Eocene succession seems to be condensed and punctuated by minor hiatus (absence of Subzone NP10a). The dominance of cool water nannofossil species in the late Maastrichtian and early Danian interval suggests a gradual decrease in the surface water paleotemperature. However, a slight warming condition prevailed around the Danian/Selandian transition as evidenced by the warm water nannofossil species. At the P/E boundary interval, the high abundance of warm-water taxa (e.g. Discoaster, Sphenolithus, Rhomboaster

  20. Sequence stratigraphy and stratigraphic trap potential of the Villeta Formation (Cretaceous), Putumayo Basin, Columbia

    SciTech Connect

    Robertson, H.C.; Cregg, A.; Cleveland, G.

    1996-12-31

    The Villeta Formation, which was deposited in -15 Ma (Cenomanian-Campanian), includes four 3rd-order sequences representing marine shelf, siliciclastic shoreface, and lower coastal-plain environments. Although these environments transgressed landward across the pre-Cretaceous basement during a 2nd-order base-level rise, several brief but important base-level falls and abrupt basinward and downward facies-shifts interrupted this trend. The 3rd-order base-level falls and subsequent transgressions led to the deposition of important hydrocarbon-bearing sandstones in the Villeta Formation. Sequence boundaries record abrupt downward facies shifts and separate black marine shales and deep-shelf limestones below from fluvial to tidally- and wave-influenced shoreface sandstones above. Each of these sands (Arenisca T, U inferior, U superior, and M2) laps out landward and passes upward into transgressive shales and thin highstand limestones. Base-level rise and retrogradation of the shoreline is indicated by upward thinning of transgressive sandstones and upward increase in marine shale. Sandstones thin or downlap basinward into shales. Transgressive deposits dominate the sequences. Highstand progradation of siliciclastic shorelines was minimal and limited by a relatively high accommodation/sediment-supply ratio. Base-level falls, however, allowed shorelines to advance basinward long distances. The stratigraphic geometries of the Villeta sandstones, as indicated by seismic data and well-log correlations, indicate that potentially large stratigraphic traps are present in the Putumayo Basin. Stratigraphic entrapment is indicated by landward onlap of the Villeta sandstones, the presence of shales and tight limestones overlying porous sandstones, and known hydrocarbon accumulations in the sandstones over structural highs.

  1. Sequence stratigraphy and stratigraphic trap potential of the Villeta Formation (Cretaceous), Putumayo Basin, Columbia

    SciTech Connect

    Robertson, H.C. ); Cregg, A.; Cleveland, G. )

    1996-01-01

    The Villeta Formation, which was deposited in -15 Ma (Cenomanian-Campanian), includes four 3rd-order sequences representing marine shelf, siliciclastic shoreface, and lower coastal-plain environments. Although these environments transgressed landward across the pre-Cretaceous basement during a 2nd-order base-level rise, several brief but important base-level falls and abrupt basinward and downward facies-shifts interrupted this trend. The 3rd-order base-level falls and subsequent transgressions led to the deposition of important hydrocarbon-bearing sandstones in the Villeta Formation. Sequence boundaries record abrupt downward facies shifts and separate black marine shales and deep-shelf limestones below from fluvial to tidally- and wave-influenced shoreface sandstones above. Each of these sands (Arenisca T, U inferior, U superior, and M2) laps out landward and passes upward into transgressive shales and thin highstand limestones. Base-level rise and retrogradation of the shoreline is indicated by upward thinning of transgressive sandstones and upward increase in marine shale. Sandstones thin or downlap basinward into shales. Transgressive deposits dominate the sequences. Highstand progradation of siliciclastic shorelines was minimal and limited by a relatively high accommodation/sediment-supply ratio. Base-level falls, however, allowed shorelines to advance basinward long distances. The stratigraphic geometries of the Villeta sandstones, as indicated by seismic data and well-log correlations, indicate that potentially large stratigraphic traps are present in the Putumayo Basin. Stratigraphic entrapment is indicated by landward onlap of the Villeta sandstones, the presence of shales and tight limestones overlying porous sandstones, and known hydrocarbon accumulations in the sandstones over structural highs.

  2. Synrift sedimentation on the northern Tethys margin: an example from the Ligurian Alps (Upper Triassic to Lower Cretaceous, Prepiedmont domain, Italy)

    NASA Astrophysics Data System (ADS)

    Decarlis, Alessandro; Lualdi, Alberto

    2011-10-01

    The Prepiedmont domain succession of the Ligurian Alps is formed by a thick Mesozoic sedimentary cover tectonically detached from its substratum. The Arnasco-Castelbianco unit preserves the most complete record of the Ligurian Prepiedmont, although completely overturned and deformed due to Alpine tectonics. It is composed of carbonate and clastic rocks deposited during the Upper Triassic to Lower Cretaceous interval. This paper is focused on the stratigraphy of the Jurassic series and its relationships to the Tethyan rifting. Each term of the sedimentary record is seen as a witness of the several phases through which the rifting took place. An early rifting phase (Late Hettangian to Early Sinemurian) brought to the formation of a normal fault system affecting the carbonate platform and favoured the development of condensed sedimentation on pelagic highs. The rapid transition from open-platform carbonates to slope-basin cherty limestones testifies the increased subsidence of the margin in the Late Sinemurian, during which moderate fault activity is recorded (intraformational breccia horizons). Until the Early Pliensbachian, a tectonic pause brought to the sedimentation of a succession of pelagic carbonates, occasionally interrupted by clastic flows. During the Late Pliensbachian (?) to Toarcian, the rifting phase followed, evidenced by the large amount of clastics and generated by renewed fault activity. Clastics flowed down into the basin as fluxoturbidites first, and then passed to breccias during the maximum tectonic pulse. In the Late Toarcian to Aalenian (?), the thermal uplift of the Briançonnais shoulder generated a basin fill of fine clastics. The following thermal subsidence (Aalenian to Tithonian) favoured the restoration of quiet basinal conditions evidenced by the deposition of radiolarites.

  3. The origin of the mineralizing fluids in different type mineralizations associated with the Upper Cretaceous Elazig Magmatic Complex, Turkey; an isotopic approach

    NASA Astrophysics Data System (ADS)

    Akgul, Muharrem

    2016-04-01

    This study examined the origin and properties of mineralized fluids by using C, O and S isotopes in different type mineralizations associated with the Upper Cretaceous Elazig Magmatic Complex. The isotopic compositions of vein type mineralizations show that the thrust zone affects the formation of the Karakas iron mineralization by meteoric and magmatic hydrothermal solution mixtures due to the average δ18OH2O value 6.40‰. The calculated δ18OH2O composition values is 5.20‰ in biotite from the Kızıldag vein type Cu-Pb-Zn mineralizations, which is consistent with a magmatic origin of the fluids. The calculated δ18OH2O composition is 4.30‰ that indicates a medium and low temperature magmatic hydrothermal fluid effect. The skarn type mineralizations isotopic compositions indicate that the calculated δ13CCO2 values are between -12.70‰ and -36.39‰ that could be late magmatic fluids that were modified by interaction with the host meta-sedimentary rocks and with meteoric water at the Birvan and Asvan iron mineralizations. Also the δ18OH2Ovalues in quartz of the Meseli iron mineralization are between 0.70‰ and 1.30‰. The lower δ18OH2O oxygen isotope composition compared to magmatic origins must be hydrothermal solutions mixing with meteoric waters. In the massive sulfide type Kavallı and Derince pyrite samples, δ34SH2S values are between 17.73‰ and 20.63‰. These values clearly indicate the volcano-sedimentary effect on hydrothermal solutions, which form the mineralization. The first findings of this study present information that all of the measured isotopic composition was modified by mixing metamorphic, magmatic and meteoric waters in the final stages of the hydrothermal solutions circulation.

  4. Hydrogeologic framework and estimates of ground-water volumes in Tertiary and upper Cretaceous hydrogeologic units in the Powder River basin, Wyoming

    USGS Publications Warehouse

    Hinaman, Kurt

    2005-01-01

    The Powder River Basin in Wyoming and Montana is an important source of energy resources for the United States. Coalbed methane gas is contained in Tertiary and upper Cretaceous hydrogeologic units in the Powder River Basin. This gas is released when water pressure in coalbeds is lowered, usually by pumping ground water. Issues related to disposal and uses of by-product water from coalbed methane production have developed, in part, due to uncertainties in hydrologic properties. One hydrologic property of primary interest is the amount of water contained in Tertiary and upper Cretaceous hydrogeologic units in the Powder River Basin. The U.S. Geological Survey, in cooperation with the Bureau of Land Management, conducted a study to describe the hydrogeologic framework and to estimate ground-water volumes in different facies of Tertiary and upper Cretaceous hydrogeologic units in the Powder River Basin in Wyoming. A geographic information system was used to compile and utilize hydrogeologic maps, to describe the hydrogeologic framework, and to estimate the volume of ground water in Tertiary and upper Cretaceous hydrogeologic units in the Powder River structural basin in Wyoming. Maps of the altitudes of potentiometric surfaces, altitudes of the tops and bottoms of hydrogeologic units, thicknesses of hydrogeologic units, percent sand of hydrogeologic units, and outcrop boundaries for the following hydrogeologic units were used: Tongue River-Wasatch aquifer, Lebo confining unit, Tullock aquifer, Upper Hell Creek confining unit, and the Fox Hills-Lower Hell Creek aquifer. Literature porosity values of 30 percent for sand and 35 percent for non-sand facies were used to calculate the volume of total ground water in each hydrogeologic unit. Literature specific yield values of 26 percent for sand and 10 percent for non-sand facies, and literature specific storage values of 0.0001 ft-1 (1/foot) for sand facies and 0.00001 ft-1 for non-sand facies, were used to calculate a

  5. Formation and tectonic evolution of the Cretaceous Jurassic Muslim Bagh ophiolitic complex, Pakistan: Implications for the composite tectonic setting of ophiolites

    NASA Astrophysics Data System (ADS)

    Khan, Mehrab; Kerr, Andrew C.; Mahmood, Khalid

    2007-10-01

    The Muslim Bagh ophiolitic complex Balochistan, Pakistan is comprised of an upper and lower nappe and represents one of a number of ophiolites in this region which mark the boundary between the Indian and Eurasian plates. These ophiolites were obducted onto the Indian continental margin around the Late Cretaceous, prior to the main collision between the Indian and Eurasian plates. The upper nappe contains mantle sequence rocks with numerous isolated gabbro plutons which we show are fed by dolerite dykes. Each pluton has a transitional dunite-rich zone at its base, and new geochemical data suggest a similar mantle source region for both the plutons and dykes. In contrast, the lower nappe consists of pillow basalts, deep-marine sediments and a mélange of ophiolitic rocks. The rocks of the upper nappe have a geochemical signature consistent with formation in an island arc environment whereas the basalts of the lower nappe contain no subduction component and are most likely to have formed at a mid-ocean ridge. The basalts and sediments of the lower nappe have been intruded by oceanic alkaline igneous rocks during the northward drift of the Indian plate. The two nappes of the Muslim Bagh ophiolitic complex are thus distinctively different in terms of their age, lithology and tectonic setting. The recognition of composite ophiolites such as this has an important bearing on the identification and interpretation of ophiolites where the plate tectonic setting is less well resolved.

  6. Formation of the Shelf-edge Cretaceous-Tertiary contact off the southeastern U.S. Coast

    USGS Publications Warehouse

    Poppe, L.J.; Hathaway, J.C.; Hall, R.E.; Commeau, R.F.

    1986-01-01

    Submarine erosion, associated with changes in position of the proto-Gulf Stream, was the dominant mechanism controlling the formation of the Cretaceous-Tertiary unconformity in AMCOR borehole 6004. Paleontologic evidence indicates that this unconformity, which is marked by a gravelly-sand enriched in glauconitic and phosphoritic concretions, represents a hiatus of about 7 m.y. Both Cretaceous and Paleocene sediments contain middle-outer neritic foraminiferal assemblages that become more diverse with distance from the contact. Of the elemental abundances measured, Al, Ba, Co, Fe, Ga, K, Mg/Ca, Mo, Ni, P, Sr/Ca, V, Y, and Zn show a strong positive correlation with proximity to the contact, probably as a result of the concentration of authigenic and heavy minerals present as lag sediments on the erosion surface. ?? 1986.

  7. Seasonal to sub-seasonal palaeoenvironmental changes in Lake Sihetun (Lower Cretaceous Yixian Formation, NE China)

    NASA Astrophysics Data System (ADS)

    Hethke, Manja; Fürsich, Franz T.; Jiang, Baoyu; Pan, Yanhong

    2013-01-01

    Sedimentary properties of the fossil-bearing deposits of Lake Sihetun (Yixian Formation, Lower Cretaceous) were investigated on a high-resolution, sub-millimetric scale. Data were obtained from three excavations and 50 thin-sections. Lake evolution is subdivided into four phases, of which Phases 2 and 3 provided suitable conditions for excellent fossil preservation. Six microfacies are recognized within these two phases: (1) allochthonous, siliciclastic laminae (26.1 μm thick on average), (2) chrysophycean cyst accumulations, (3) tuffaceous silt, (4) lacustrine chemical precipitates, (5) tuff and (6) normal-graded, sandy to silty siliciclastics. Phase 2 is characterized by Microfacies 1-5 and Phase 3 by Microfacies 6. Biofilms are common, and mass occurrences of framboids (pyrite pseudomorphs) are occurring in sediments of Phase 2. Varves can be verified for Microfacies 2 and 4 (179 μm thick). Thicknesses of Microfacies 2 highly fluctuate depending on the occurrence of seasonal heavier rains, which led to deposition of tuffaceous silt layers (Microfacies 3). Meromictic conditions dominated Phase 2, but recurrent mixing is demonstrated by short-lived colonization events by a benthic invertebrate fauna. The transition of Phase 2 to holomictic Phase 3 is marked by a dramatic increase in sediment yield associated with a change from dry to humid climates. Fossil preservation differs according to the diverse physical and chemical conditions during lake evolution. Phase 2 yields framboid replacement of organic tissue and excellent preservation of growth increments of clam-shrimp carapaces, which are poorly preserved in Phase 3. Conversely, though exhibiting a different mode of preservation, insect fossils are superbly preserved as dark stains sealed by silica coatings during Phase 3.

  8. Seismic expression of catastrophic slope failure: Lower Cretaceous Torok Formation, North Slope of Alaska

    SciTech Connect

    Kerr, R.S.

    1985-02-01

    Seismic geometries in the deep marine Torok Formation illustrate that catastrophic slope failure involving both slope and basin-plain sediments occurred during Early Cretaceous time on the North Slope of Alaska. The magnitude of the failure emphasizes the importance of slumping and sliding as processes of mass transport of sediment in the deep marine environment. Torok sandstones and shales were deposited on continental slopes, basin plains, and submarine fans. Fluvial-deltaic sands and shales of the Nanushuk Group are the time-equivalent shelf deposits. The nanushuk-Torok relationship is expressed seismically as offlapping reflectors that record shelf-edge progradation. Slumps and slides are common on Torok slopes where gradients of up to 10/sup 0/ are documented. The largest such feature, located near Harrison Bay, is 1500 mi/sup 2/ in area and 2000 ft thick. The disturbed zone is lobate in plan view, wedge shaped in cross section, and thins basinward from a dramatic scarp deeply incised into Torok foreset beds. Seismically, the slide is expressed as a series of remnants of undisturbed or rotated glide blocks that strike parallel with the slump scarp and are encased in chaotically bedded slump debris. Geometric similarities to the Turnagain Heights slide (Anchorage, 1964) suggest block gliding as the mechanism of slope failure. Because the Torok was initially sand-poor, wells drilled through glide blocks and slump debris encountered predominantly shale. Understanding similar seismic geometries in other slope systems will aid in their evaluation as hydrocarbon traps. Favorable reservoir and trap scenarios include turbidite sands in remnant blocks trapped against slump fill and younger turbidite sands ponded behind remnant topography.

  9. Applications of ichnology to hydrogeology, with examples from the Cape Fear Formation (Cretaceous), South Carolina

    SciTech Connect

    Martin, A.J. . Geosciences Program); Simones, G.C. )

    1992-01-01

    Ichnology, the study of modern and ancient traces left by organisms, has provided supplemental information to geologic subdisciplines such as sedimentology and stratigraphy. The major objective of the authors paper is to emphasize the valuable information that can be conveyed by trace fossils in the investigation of hydrogeologic units. Bioturbation has a net effect of mixing different types and layers of sediments, such as introducing clays into sands and vice versa. This mixing can decrease porosity and permeability of sandy units, thus changing potential aquifers into confining units. For example, a sandy fluvial deposit will contain distinctive nonmarine trace fossils, thus defining channel sands that may serve as permeable conduits for ground-water flow. In contrast, a sandy shelf deposit will contain marine trace fossils in a sand body geometry that will be markedly different from aquifers produced in nonmarine environments. Bioturbation also causes geochemical and diagenetic changes in sediments, causing irrigation of previously anoxic sediments and precipitation of ion oxides. The Cretaceous Cape Fear Formation of the Atlantic Coastal Plain, in the subsurface of South Carolina, is presented as an example of a hydrogeologic unit that has been reinterpreted using ichnologic data. Extensive bioturbation caused mixing of clays and sands in Cape Fear sediments, which resulted in the Cape Fear becoming a regional confining system. Trace fossil assemblages indicate a brackish water environment, perhaps estuarine, for the Cape Fear, as opposed to previous interpretations of fluvial and deltaic environments. Bioturbated zones also have significantly more oxidized iron than unbioturbated zones, highlighting potential effects on ground-water quality.

  10. Differentiation of delta-front and barrier lithofacies of the Upper Cretaceous Pictured Cliffs Sandstone, southwest San Juan Basin, New Mexico.

    USGS Publications Warehouse

    Flores, R.M.; Erpenbeck, Michael F.

    1981-01-01

    This Sandstone represents a regressive littoral marine unit deposited during the final retreat of the Cretaceous epeiric sea. Differences in rock type, internal and penecontemporaneous deformation structures, textural sequences, mineral composition and trace fossil content permit recognition of laterally contemporaneous delta-front and barrier lithofacies. The delta-front lithofacies consists of distal bar, distributary mouth bar, and distributary channel deposits. The barrier lithofacies consists of shoreface, beach, washover channel, tidal inlet, tidal channel, and ebb-tidal delta deposits; these lithofacies are coarsening-upward sequences of shale, siltstone and sandstone, locally scoured in the upper part by fining-upward channel deposits.-from Authors

  11. Sedimentary evolution of the upper Cretaceous and late Oligocene sequences, and its relation to oil production, North Monagas area, Eastern Venezuela

    SciTech Connect

    Sambrano, J.; Rojas, B.; Rendon, J.; Chigne, R.; Maguregui, J.

    1996-08-01

    The most important oil reservoirs of the Eastern Venezuela Basin are located in the North Monagas Area. These reservoirs are contained within a 3500 ft Cretaceous to Late Oligocene sedimentary section. Daily production is rated at about 350 MBO and 1000 MMCFG. At this moment, these reservoirs are undergoing special studies, in order to establish enhanced recovery projects, for which heterogeneity definition is very important. The database consisted of log analyses of 136 wells, sedimentological and biostratigraphic interpretation of 10,200 ft of cores, and biostratigraphic interpretation of ditch samples from 13 wells. Sedimentary models, based on facies analyses and deltaic conceptual models of 31 separate genetic units were defined. The models allowed for the interpretation of paleoenvironments, sedimentary facies architecture, direction of sedimentation and depocenters. The preferred sediment orientation was determined to be West-East. In the Santa Barbara and Pirital reservoirs the Late Oligocene sediments are composed of fluvial deposits, and the Cretaceous sediments of estuarine deposits. In the Carito-Mulata reservoirs, the Late Oligocene sediments are composed of fluvial to marine deposits, and the Upper Cretaceous sediments of estuarine deposits. Possible preferred transmissibility pathways for fluid injection were described, providing a great support for the enhanced recovery phases of these reservoirs.

  12. New Specimens of Nemegtomaia from the Baruungoyot and Nemegt Formations (Late Cretaceous) of Mongolia

    PubMed Central

    Fanti, Federico; Currie, Philip J.; Badamgarav, Demchig

    2012-01-01

    Two new specimens of the oviraptorid theropod Nemegtomaia barsboldi from the Nemegt Basin of southern Mongolia are described. Specimen MPC-D 107/15 was collected from the upper beds of the Baruungoyot Formation (Campanian-Maastrichtian), and is a nest of eggs with the skeleton of the assumed parent of Nemegtomaia on top in brooding position. Much of the skeleton was damaged by colonies of dermestid coleopterans prior to its complete burial. However, diagnostic characters are recovered from the parts preserved, including the skull, partial forelimbs (including the left hand), legs, and distal portions of both feet. Nemegtomaia represents the fourth known genus of oviraptorid for which individuals have been found on nests of eggs. The second new specimen, MPC-D 107/16, was collected a few kilometers to the east in basal deposits of the Nemegt Formation, and includes both hands and femora of a smaller Nemegtomaia individual. The two formations and their diverse fossil assemblages have been considered to represent sequential time periods and different environments, but data presented here indicate partial overlap across the Baruungoyot-Nemegt transition. All other known oviraptorids from Mongolia and China are known exclusively from xeric or semi-arid environments. However, this study documents that Nemegtomaia is found in both arid/aeolian (Baruungoyot Formation) and more humid/fluvial (Nemegt Formation) facies. PMID:22347465

  13. Geochemistry of fossiliferous carbonate concretions from the Cretaceous Santana Formation - assessing the role of microbial processes

    NASA Astrophysics Data System (ADS)

    Heimhofer, Ulrich; Schwark, Lorenz; Ariztegui, Daniel; Martill, David M.; Immenhauser, Adrian

    2010-05-01

    Exceptional fossil preservation (incl. soft-tissue phosphatization) within organic-rich black shales is often associated with the formation of a protective carbonate shell surrounding the fossil specimen. Whereas the mechanisms controlling soft-tissue mineralization during the earliest stage of fossilization are considerably well understood (e.g. Briggs and Kear, 1993), only limited information is currently available on the complex biogeochemical processes which lead to the precipitation of the concretionary carbonate mantle around the fossils. This study focuses on the organic and inorganic geochemistry of carbonate concretions derived from black shale deposits of the Early Cretaceous Santana Formation, Araripe Basin, NE Brazil (Martill, 1993; Heimhofer et al. 2008). This konservat-type fossil lagerstätte is world famous for its fossiliferous concretions hosting an exceptionally preserved fish and reptile fauna. The principle aim is twofold including (1) identification of the type and source of organic matter trapped within the Santana concretions and (2) assessment of the different microbial or microbially-mediated processes associated with successive concretion growth during early burial. Based on sedimentological evidence and palaeoenvironmental considerations, the involvement of a prokaryotic mat in early fossilization of the Santana biota has been proposed (Martill, 1988). At this stage, 3 different carbonate concretions hosting fossil fish remains (incl. Notelops brama, Calamopleurus sp. und an unknown specimen) have been analysed with a combined approach including organic molecular geochemistry, high-resolution stable isotope analysis, micro-XRF scanning and sedimentary petrography. Petrographic inspection shows a distinct zonal pattern of the carbonate shell surrounding the fossils. The innermost zone I shows an undulating and discontinuous lamination superimposed on a clotted fabric. Zone II is characterized by the frequent abundance of finely dispersed

  14. Sedimentology and Stratigraphic architecture of the early Cretaceous Alpian-Aptian succession of the Kiklah Formation, Jabal Nafusah, NW Libya

    NASA Astrophysics Data System (ADS)

    Hlal, Osama

    2016-04-01

    Kiklah Formation is presents on the Jabal Nafusah escarpment for almost 400 km from the Tunisian border to the east of Gharyan. Kiklah Formation overlies the Early Cretaceous, Jurassic and Triassic sediments of Jabal Nafusah with marked unconformity. On the other hand, it is unconformably overlain by the Sidi as Sid Formation. This contact with overlying units is angular unconformity as it is evident only in the central Gharyan area. The Kiklah Formation consists mainly of continental deposits such as conglomeratic sandstone, pebble sandstone, and mudstone with minor lacustrine interbeds of reddish yellow to greenish claystone. In addition, these rocks were formed by a braided river system carrying heavy sediment loads, with frequent shifting of the principal channels. SEM studies show pitting and breakage features on the sand grains which are diagnostic of Fluvial depositional environment. In the Nafusah region the Kiklah Formation varies in thickness westward from absence near Gharyan to over 610 m in Tunisian subsurface.

  15. The floating astronomical time scale for the terrestrial Late Cretaceous Qingshankou Formation from the Songliao Basin of Northeast China and its stratigraphic and paleoclimate implications

    NASA Astrophysics Data System (ADS)

    Wu, Huaichun; Zhang, Shihong; Jiang, Ganqing; Huang, Qinghua

    2009-02-01

    The Upper Cretaceous Qingshankou Formation (K 2qn) in the Songliao Basin (SLB) of Northeast China consists of up to 550 m thick, lacustrine mudstone and shale that constitute one of the most important source rocks of the Daqing oil field. A high-resolution cyclostratigraphic analysis of the natural gamma-ray logging from 10 wells of the Qingshankou Formation (K 2qn) reveals orbital cycles of precession (20 ka), obliquity (40 ka) and eccentricity (100 ka and 405 ka), providing strong evidence for astronomically driven climate changes in the Late Cretaceous terrestrial environments. Floating astronomical time scales (ATS) are established for all sections, which demonstrate variable durations of K 2qn across the basin (1.09 Ma-5.20 Ma) and strong diachroneity of the lacustrine strata. Four periods of high depositional rates can be identified in the central parts of the basin, possibly recording deposition during times of sustained wet climate and high chemical weathering. An ATS established from well M206 in the central depression zone of the basin, where the most complete and stable Milankovitch cycles are present, suggests that the maximum duration of the K 2qn is 5.20 Ma (from 94.27 Ma to 89.07 Ma; Late Cenomanian to Early Coniacian). The lacustrine anoxic event 1 (LAE1) at the Cenomanian-Turonian boundary lasted ~ 210-310 ka, during which the most prolific petroleum source rocks in SLB were deposited. The onset (~ 94.21-94.18 Ma) and duration (~ 210-310 Ka) of LAE1 in SLB are comparable to those of the oceanic anoxic event 2 (OAE2; onset at 94.21 Ma and duration of ~ 320-900 ka), suggesting that the same trigger mechanism, such as increased atmospheric CO 2 from large-scale igneous activity, may have initiated high primary productivity and organic carbon burial in both marine and terrestrial systems.

  16. Spectroscopic studies of the fish fossils (Cladocyclus gardneri and Vinctifer comptoni) from the Ipubi Formation of the Cretaceous Period.

    PubMed

    Sousa Filho, F E; da Silva, J H; Saraiva, G D; Abagaro, B T O; Barros, O A; Saraiva, A A F; Viana, B C; Freire, P T C

    2016-03-15

    Fossils are mineralized remains or traces from animals, plants and other organisms aged to about 10(8)years. The chemical processes of fossilization are dated back from old geological periods on Earth. The understanding of these processes and the structure of the fossils are one of the goals of paleontology and geology in the sedimentary environments. Many researches have tried to unveil details about special kinds of biological samples; however, a lack of data is noticed for various other specimens. This study reports the investigations through infrared spectroscopy, X-ray fluorescence and X-ray diffraction measurements for two types of fish fossils from the Cretaceous Period. The sample of Cladocyclus gardneri and Vinctifer comptoni fossils were collected from the Ipubi Formation, being one of the less studied, among the formations that constitute the important Santana group in the Araripe Basin, Brazil. The results obtained through different techniques, showed that the C. gardneri fish fossil contains hydroxyapatite and calcite as constituents whereas its rock matrix was formed by calcite, quartz and pyrite. Regarding the V. comptoni, the measurements confirmed the presence of hydroxyapatite in the fossil and its rock matrix gypsum, pyrite, quartz and calcite. The above scientific data contributed to the understanding the fossil formation in the Ipubi Formation, an important environment of the Cretaceous Period, which is rich in well-preserved fossils from different species.

  17. Spectroscopic studies of the fish fossils (Cladocyclus gardneri and Vinctifer comptoni) from the Ipubi Formation of the Cretaceous Period

    NASA Astrophysics Data System (ADS)

    Sousa Filho, F. E.; da Silva, J. H.; Saraiva, G. D.; Abagaro, B. T. O.; Barros, O. A.; Saraiva, A. A. F.; Viana, B. C.; Freire, P. T. C.

    2016-03-01

    Fossils are mineralized remains or traces from animals, plants and other organisms aged to about 108 years. The chemical processes of fossilization are dated back from old geological periods on Earth. The understanding of these processes and the structure of the fossils are one of the goals of paleontology and geology in the sedimentary environments. Many researches have tried to unveil details about special kinds of biological samples; however, a lack of data is noticed for various other specimens. This study reports the investigations through infrared spectroscopy, X-ray fluorescence and X-ray diffraction measurements for two types of fish fossils from the Cretaceous Period. The sample of Cladocyclus gardneri and Vinctifer comptoni fossils were collected from the Ipubi Formation, being one of the less studied, among the formations that constitute the important Santana group in the Araripe Basin, Brazil. The results obtained through different techniques, showed that the C. gardneri fish fossil contains hydroxyapatite and calcite as constituents whereas its rock matrix was formed by calcite, quartz and pyrite. Regarding the V. comptoni, the measurements confirmed the presence of hydroxyapatite in the fossil and its rock matrix gypsum, pyrite, quartz and calcite. The above scientific data contributed to the understanding the fossil formation in the Ipubi Formation, an important environment of the Cretaceous Period, which is rich in well-preserved fossils from different species.

  18. Spectroscopic studies of the fish fossils (Cladocyclus gardneri and Vinctifer comptoni) from the Ipubi Formation of the Cretaceous Period.

    PubMed

    Sousa Filho, F E; da Silva, J H; Saraiva, G D; Abagaro, B T O; Barros, O A; Saraiva, A A F; Viana, B C; Freire, P T C

    2016-03-15

    Fossils are mineralized remains or traces from animals, plants and other organisms aged to about 10(8)years. The chemical processes of fossilization are dated back from old geological periods on Earth. The understanding of these processes and the structure of the fossils are one of the goals of paleontology and geology in the sedimentary environments. Many researches have tried to unveil details about special kinds of biological samples; however, a lack of data is noticed for various other specimens. This study reports the investigations through infrared spectroscopy, X-ray fluorescence and X-ray diffraction measurements for two types of fish fossils from the Cretaceous Period. The sample of Cladocyclus gardneri and Vinctifer comptoni fossils were collected from the Ipubi Formation, being one of the less studied, among the formations that constitute the important Santana group in the Araripe Basin, Brazil. The results obtained through different techniques, showed that the C. gardneri fish fossil contains hydroxyapatite and calcite as constituents whereas its rock matrix was formed by calcite, quartz and pyrite. Regarding the V. comptoni, the measurements confirmed the presence of hydroxyapatite in the fossil and its rock matrix gypsum, pyrite, quartz and calcite. The above scientific data contributed to the understanding the fossil formation in the Ipubi Formation, an important environment of the Cretaceous Period, which is rich in well-preserved fossils from different species. PMID:26745511

  19. Dynamics of Late Cretaceous rocky shores (Rosario Formation) from Baja California, Mexico

    SciTech Connect

    Lescinsky, H.L. ); Ledesma-Vazquez, J. ); Johnson, M.E. )

    1991-04-01

    Two rocky-shore deposits are described at localities of Late Cretaceous age in Baja California, Mexico. The main locality, at Las Minas, is characterized by a carbonate matrix containing clasts derived from an underlying andesite flow. Basal boulders give way up section to smaller cobbles and silt, indicating a transgression. The biotas from the sites include encrusting forms (coralline algae, bryozoans, serpulids, ostreids, spondylids), pholadid bivalve borings, and several nestling and mobile taxa. The well exposed boulder zone contains clusters of nestling pectinids preserved in growth position. This is the first such observation from an ancient rocky shore. Echinoids also lived within the relatively stable boulder interstices. Rocky-shore biotas of Late Cretaceous age from around the world contain many elements in common, including large encrusting oysters, spondylids, serpulids, rhynconellid brachiopods, and echinoids. Other groups common to rocky shores today are found at only some Cretaceous localities (e.g., barnacles, trochid and cerithiid gastropods, limpets, chitons). More archaic taxa, such as crinoids and large inarticulate brachiopods, are rarely represented at the known Cretaceous localities. Reconstructions of the biotas of ancient rocky shores offer a new avenue for the study of evolution on hard substrates. As the number and quality of described rocky-shore localities increases, it will be possible to put into a broader context evolutionary trends derived strictly from hard-grounds or other hard-substrate types.

  20. Palynological analysis of floral changes caused by repeated volcanic ash burial of a coal-forming upper Cretaceous peat swamp, Utah, U. S. A

    SciTech Connect

    Dufek, D.A.

    1987-01-01

    The Ferron Sandstone C coal horizon and several outcrop samples from the upper Tununk Shale, Ferron Sandstone, and lower Bluegate Shale Members of the Mancos Shale from the Castle Valley area of east-central Utah were studied palynologically. This information was used to reconstruct the floristic assemblages of the coal-forming peat swamps, to determine the extent of destruction of the vegetation by repeated burial by volcanic ash, and the sequence of plant community paleosuccession following such events. Seven floristic assemblages are differentiated in the coal swamps. Both lateral (geographic) and vertical (successional) floristic trends are identified in the Ferron C. coal. Low diversity, fern dominated assemblages represent early successional communities. The mature coal swamp consists primarily of the Gymnosperm Assemblage. Periodic volcanic eruptions had varying effects on the paleocommunity structure of the Ferron C coal swamp vegetation. The thicker ash fall accumulations were more devastating to the flora than the thin ash accumulations. Hydrologic, pedologic, and floristic changes are associated with the thickest ash fall. The Ferron Sandstone palynoflora (middle to late Turonian) is similar to other western US Middle-Cretaceous floras. No depositional or age relationships were established between productive samples from northern and southern Castle Valley. The upper Tununk Shale palynoflora is characteristic of the Cenomanian-Turonian (Middle Cretaceous). The lower Bluegate Shale palynoflora is latest Turonian in age or younger. Both the Tununk Shale and the Bluegate Shale yielded palynofloras characteristic of marine depositional environments.

  1. Petrophysical properties of carbonate rocks: example from the cretaceous Jandaira Formation, Potiguar basin - Brazil

    NASA Astrophysics Data System (ADS)

    Nogueira, Francisco; Soares, José; Bezerra, Francisco; Cavalcanti, Bruno; Cazarin, Caroline

    2015-04-01

    Carbonate sediments are prone to rapid and pervasive diagenetic alterations that change the mineralogy and pore structure within carbonate units. In particular, cementation and dissolution processes continuously modify the pore structure to create or destroy porosity. In extreme cases these modifications can completely change the mineralogy from calcite to dolomite, in the properties of rock for soil (Caliche), or reverse the pore distribution whereby original grains are dissolved to produce pores as the original pore space is filled with cement to form the rock. These processes are common in fractured carbonate units. All these modifications alter the elastic properties of the rock and, therefore, the sonic velocity. This study presents the result of relationship among diagenesis, porosity, grain density, and sonic velocity, in limestones, dolomites and caliche samples from the Jandaíra Formation, Potiguar basin, Brasil. This stratigraphic unit have been subjected to fracturing since the late Cretaceous. The rock and soil samples were collected in outcrops, prepared as plugs, and analyzed at ambient temperature. The porosity and grain density analysis were performed under ambient pressure, while elastic properties analyses were conducted with samples under confining pressure between 5 and 40 MPa. The result is a wide range of sonic velocity in carbonates, in which compressional-wave velocity (VP) ranges from 3507 to 6119 m/s and shear-wave velocity (VS) range from 2114 to 3451 m/s. The ratio VS1/VS2 indicate a level of anisotropy equal to 2%, without any clear relationship with porosity. The elastics properties are affected by rock alteration process or by modification of mineral composition, due to the presence of clay minerals and organic matter, The porosity and grain density values range from 3.2 to 21.5%, and 2.7 to 2.8 (g/cm3), respectively. The grain density analysis in the carbonate rocks indicate the existence of two groups: the first group of calcareous

  2. Geochemical and Petrographic Characterization of Ash in the Cretaceous Eagle Ford Formation

    NASA Astrophysics Data System (ADS)

    Ronay, E.; Lee, C. T.

    2015-12-01

    The Eagle Ford Formation is composed of highly laminated, organic rich shales and marls interbedded with volcanic ash. Discrete ash beds are easy to identify in outcrop as recessed layers between more resistant rock. In the finely laminated shales, the ash cannot be identified visually, which fosters the questions of whether ash is present in these shales and how that can be determined. The ash is thought to come from volcanic activity in western North America during the Cenomanian and Turonian, depositing in the Western Interior Seaway in what is now South Texas. Samples of known ash-rich beds from the Eagle Ford were analyzed using micro-XRF and thin section petrography in conjunction with ICP-MS laser ablation to determine the geochemical composition of the samples. The high CaCO3 content of the marls diluted the ash in each sample so elemental data were used to separate the two components. The amount of Ca in the ash from the total measured Ca was unknown. Carbonate takes Sr but not Al, therefore the y-intercept of a Ca/Al vs. Sr/Al graph gave the concentration of Ca in the non-carbonate components. This method was used for every cation to gather a generalized overall composition of the present day ash. The ash was found to have been altered to clays, resulting in a substantial loss of Si and thereby making the original composition of the ash indeterminable. However, certain elements like Ti and Zr are not as significantly affected by weathering. Using an empirical relationship between Ti/Zr and SiO2 in magmatic rocks from the Cretaceous Peninsular Ranges batholith, the likely source of ash, our measured Ti/Zr was used to determine the original SiO2 percentage in the ash, giving a range of 60-75 wt%. This was also checked by a Ti/Al regression analysis from the same Peninsular Ranges data, which gave a range of 67-72 wt% SiO2. These results suggest that the ash came from andesitic to rhyolitic eruptions. The discrepancy in Ti/Al and Ti/Zr calculated SiO2

  3. Revision of the Cretaceous fossil plant-assemblage from Gardeshwar (Gujarat, India): A conifer dominated floral association from an Upper Gondwana sequence on the West Coast of India

    NASA Astrophysics Data System (ADS)

    Jana, Brajendra Nath; King, Sarah C.; Hilton, Jason

    2013-09-01

    A small but diverse fossil plant assemblage from Gardeshwar in Gujarat Province of western India is reinvestigated, based on analysis of recently collected specimens that represent previously unrecognised taxa in combination with a critical review of previously reported taxa from the site. The assemblage is dominated by conifers including Brachyphyllum Brongniart, Elatocladus Halle, Pagiophyllum Heer, the cone Conites Sternberg, and ovulate scales of an araucarian conifer. Other plant groups are rare but include notable occurrences of the pteridophytes Lycopodites Lindley and Hutton and Gleichenia Smith, and the seed fern Sphenopteris (Brongniart) Sternberg. This assemblage is important as it represents the only datable fossils available from the Gardeshwar Formation and from the information presented we conclude it belongs to the Lower Cretaceous Allocladus-Brachyphyllum-Pagiophyllum floral biozone. The Gardeshwar assemblage association is unusual as it lacks the distinctive genus Allocladus but includes other taxa more typical of the Lower Cretaceous fern-dominated Weichselia-Onychiopsis-Gleichenia floral biozone, and may represent a transitional assemblage with characters of both biozones. However, this investigation highlights the lack of detailed stratigraphic analyses on the Lower Cretaceous sedimentary sequences of the west coast of India from which it remains uncertain if these two ‘biozones' are of different ages or whether they represent stratigraphically contemporaneous but ecologically distinct environments.

  4. Stratigraphy and paleogeography of the Cretaceous in Arabian Peninsula

    SciTech Connect

    Alsharhan, A.S.; Nairn, A.E.M.

    1986-05-01

    The Cretaceous of the Arabian Peninsula is divided into three major units by regional unconformities: Lower Cretaceous Thamama Group (Berriasian-middle Aptian), middle Cretaceous Wasia Group (Albian-Turonian), and Upper Cretaceous Aruma Group (Coniacian-Maestrichtian). The profusion of named stratigraphic units in the area reflects not only the lithologic variation resulting from facies changes, but also terminologies adopted by different companies. The authors provide a stratigraphic nomenclature defining standard type sections and indicate synonymies, which follow the recommendation of 10th Geological Liaison Meeting and hence are acceptable to operators in the area. The sedimentologic history of the area was presented in a series of paleogeographic maps, which they relate to the regional tectonic framework. The maps show a predominantly carbonate shelf ramp bordering a land area to the north and west. The principal change in depositional environment occurs during the Upper Cretaceous, as a result of tectonic activity. Less significant changes are attributed to eustatic sea level fluctuations, on which tilting caused by tectonic movement may be superposed during the Lower and middle Cretaceous. The major producing horizons lie below the regional unconformities; secondary porosity in the shelf reefal buildups was developed during subaerial exposure in the Shuaiba Formation (early-middle Aptian), in the Mishrif Formation (late Cenomanian), and in the Simsima Formation (Maestrichtian).

  5. Cretaceous evolution of the Indian Plate and consequences for the formation, deformation and obduction of adjacent oceanic crust

    NASA Astrophysics Data System (ADS)

    Gaina, C.; Van Hinsbergen, D. J.; Spakman, W.

    2012-12-01

    As part of the gradual Gondwana dispersion that started in the Jurassic, the Indian tectonic block was rifted away from the Antarctica-Australian margins, probably in the Early-Mid Cretaceous and started its long journey to the north until it collided with Eurasia in the Tertiary. In this contribution first we will revise geophysical and geological evidences for the formation of oceanic crust between India and Antarctica, India and Madagascar, and India and Somali/Arabian margins. This information and possible oceanic basin age interpretation are placed into regional kinematic models. Three important compressional events NW and W of the Indian plate are the result of the opening of the Enderby Basin from 132 to 124 Ma, the first phase of seafloor spreading in the Mascarene basin approximately from 84 to 80 Ma, and the incipient opening of the Arabian Sea and the Seychelles microplate formation around 65 to 60 Ma. Based on retrodeformation of the Afghan-Pakistan part of the India-Asia collision zone and the eastern Oman margin, the ages of regional ophiolite emplacement and crystallization of its oceanic crust, as well as the plate tectonic setting of these ophiolites inferred from its geochemistry, we evaluate possible scenarios for the formation of intra-oceanic subduction zones and their evolution until ophiolite emplacement time. Our kinematic scenarios are constructed for several regional models and are discussed in the light of global tomographic models that may image some of the subducted Cretaceous oceanic lithosphere.

  6. New occurrences of fossilized feathers: systematics and taphonomy of the Santana Formation of the Araripe Basin (Cretaceous), NE, Brazil

    PubMed Central

    Anelli, Luiz Eduardo; Petri, Setembrino; Romero, Guilherme Raffaeli

    2016-01-01

    Here we describe three fossil feathers from the Early Cretaceous Santana Formation of the Araripe Basin, Brazil. Feathers are the most complex multiform vertebrate integuments; they perform different functions, occurring in both avian and non-avian dinosaurs. Despite their rarity, fossil feathers have been found across the world. Most of the Brazilian feather fossil record comes from the Santana Formation. This formation is composed of two members: Crato (lake) and Romualdo (lagoon); both of which are predominantly reduced deposits, precluding bottom dwelling organisms, resulting in exceptional preservation of the fossils. Despite arid and hot conditions during the Cretaceous, life teemed in the adjacency of this paleolake. Feathered non-avian dinosaurs have not yet been described from the Crato Member, even though there are suggestions of their presence in nearby basins. Our description of the three feathers from the Crato laminated limestone reveals that, despite the small sample size, they can be referred to coelurosaurian theropods. Moreover, based on comparisons with extant feather morphotypes they can be identified as one contour feather and two downy feathers. Despite their rareness and low taxonomic potential, fossilized feathers can offer insights about the paleobiology of its owners and the paleoecology of the Araripe Basin. PMID:27441102

  7. New occurrences of fossilized feathers: systematics and taphonomy of the Santana Formation of the Araripe Basin (Cretaceous), NE, Brazil.

    PubMed

    Prado, Gustavo M E M; Anelli, Luiz Eduardo; Petri, Setembrino; Romero, Guilherme Raffaeli

    2016-01-01

    Here we describe three fossil feathers from the Early Cretaceous Santana Formation of the Araripe Basin, Brazil. Feathers are the most complex multiform vertebrate integuments; they perform different functions, occurring in both avian and non-avian dinosaurs. Despite their rarity, fossil feathers have been found across the world. Most of the Brazilian feather fossil record comes from the Santana Formation. This formation is composed of two members: Crato (lake) and Romualdo (lagoon); both of which are predominantly reduced deposits, precluding bottom dwelling organisms, resulting in exceptional preservation of the fossils. Despite arid and hot conditions during the Cretaceous, life teemed in the adjacency of this paleolake. Feathered non-avian dinosaurs have not yet been described from the Crato Member, even though there are suggestions of their presence in nearby basins. Our description of the three feathers from the Crato laminated limestone reveals that, despite the small sample size, they can be referred to coelurosaurian theropods. Moreover, based on comparisons with extant feather morphotypes they can be identified as one contour feather and two downy feathers. Despite their rareness and low taxonomic potential, fossilized feathers can offer insights about the paleobiology of its owners and the paleoecology of the Araripe Basin.

  8. New occurrences of fossilized feathers: systematics and taphonomy of the Santana Formation of the Araripe Basin (Cretaceous), NE, Brazil.

    PubMed

    Prado, Gustavo M E M; Anelli, Luiz Eduardo; Petri, Setembrino; Romero, Guilherme Raffaeli

    2016-01-01

    Here we describe three fossil feathers from the Early Cretaceous Santana Formation of the Araripe Basin, Brazil. Feathers are the most complex multiform vertebrate integuments; they perform different functions, occurring in both avian and non-avian dinosaurs. Despite their rarity, fossil feathers have been found across the world. Most of the Brazilian feather fossil record comes from the Santana Formation. This formation is composed of two members: Crato (lake) and Romualdo (lagoon); both of which are predominantly reduced deposits, precluding bottom dwelling organisms, resulting in exceptional preservation of the fossils. Despite arid and hot conditions during the Cretaceous, life teemed in the adjacency of this paleolake. Feathered non-avian dinosaurs have not yet been described from the Crato Member, even though there are suggestions of their presence in nearby basins. Our description of the three feathers from the Crato laminated limestone reveals that, despite the small sample size, they can be referred to coelurosaurian theropods. Moreover, based on comparisons with extant feather morphotypes they can be identified as one contour feather and two downy feathers. Despite their rareness and low taxonomic potential, fossilized feathers can offer insights about the paleobiology of its owners and the paleoecology of the Araripe Basin. PMID:27441102

  9. Fracture characterization of flysch formation by terrestrial digital photogrammetry: an example in the Antola Formation (upper Staffora Valley, Italy)

    NASA Astrophysics Data System (ADS)

    Meisina, Claudia; Menegoni, Niccolò; Perotti, Cesare

    2016-04-01

    Geomechanical characterization of flysch formations plays an important role for its implication in slope stability and fluids circulation, especially in Apenninic areas. The Antola Formation of Upper Cretaceous age crops out extensively in the Northern Apennines and provides an important case of study. It consists of turbiditic graded units of calcareous sandstones, sandstones, marlstones, and shales and is interpreted as a deep-sea basin plain deposit, with lateral facies variations which range from proximal, thick-bedded turbidities to distal turbidites that show predominantly thickening upward cycles and have a high percentage of shale. It is in general characterized by folds developed in absence of metamorphism and a usually high degree of fracturation. The presence of well developed fracture networks enhances circulation of fluid and therefore alteration of the less competent layers causing problems of slope stability. Fracture characterization of Antola Formation based on field survey is very time consuming and often limited by the insufficient availability and inaccessibility of outcrops. For this reason, terrestrial remote sensing and in particular terrestrial digital photogrammetry has been applied to investigate the geomechanical features of the formation in the upper Staffora Valley (Northern Italy). Digital photogrammetry allows to generate by Structure from Motion (SfM) technique a 3D point cloud that represents the Digital Outcrop Model (DOM). New technologies allow to associate appropriate texture to the point cloud from the images, in order to preserve important visual information. The analysis of several textured 3D DOMs allows to digitally acquire a large amount of data on discontinuities parameters such as orientation, spacing, aperture, persistence and filling, in order to better characterize the rock mass. Some tests performed by field survey data acquisition to validate the digitally collected data, gave positive results, showing differences

  10. Depositional environments, diagenesis, and porosity of upper cretaceous volcanic-rich Tokio sandstone reservoirs, Haynesville Field, Clairborne Parish, Louisiana

    SciTech Connect

    Clark, W.J.

    1995-10-01

    Tokio Formation sandstones produce oil from volcanic-rich to quartzose lithic sandstones in the Haynesville Field. The Tokio interval is approximately 210 feet thick and has been divided into four sandstone zones separated by shales or scoured contacts. In ascending order, the four zones are the RA, S3, S2, and S1. The RA is composed of quartzose sublitharenites inferred to have been deposited in delta front bars and distributary channels. The upper three zones are composed of sublitharenite and feldspathic litharenite to quartzose litharenite. The upper sands are interpreted to have been deposited in littoral environments including storm influenced shelf, tidal flats and channels, and barrier island/strand plain. The diagenesis of these sands is strongly related to composition: greater percentages of cements and secondary porosity occur in lithic-rich sandstones. Diagenetic cements in quartzose sandstones are mainly quartz overgrowths with minor early K-spar overgrowths on plagioclase, early chlorite-rims, and late patchy calcite, pyrite, and rare dolomite and siderite. Diagenesis in lithic-rich sands includes greater amounts of chlorite rim and pore-filling kaolinite cements and less quartz-overgrowth and other cements. The effect of the original mineralogy and diagenetic minerals on wireline logs includes: (1) reduction of SP due to cements, (2) increase in GR response due to K-spar and volcanic detritus, (3) higher resistivity due to carbonate minerals, and (4) increase in irreducible water saturation due to pore-lining and pore-filling clay. Thus, potential reservoir zones with lithic-rich sandstones like the Tokio could be overlooked in many areas around the world.

  11. Altered volcanic ash layers of the Late Cretaceous San Felipe Formation, Sierra Madre Oriental (Northeastern Mexico): Usbnd Pb geochronology, provenance and tectonic setting

    NASA Astrophysics Data System (ADS)

    Velasco-Tapia, Fernando; Martínez-Paco, Margarita; Iriondo, Alexander; Ocampo-Díaz, Yam Zul Ernesto; Cruz-Gámez, Esther María; Ramos-Ledezma, Andrés; Andaverde, Jorge Alberto; Ostrooumov, Mikhail; Masuch, Dirk

    2016-10-01

    A detailed petrographic, geochemical, and Usbnd Pb geochronological study of altered volcanic ash layers, collected in eight outcrops of the Late Cretaceous San Felipe Formation (Sierra Madre Oriental, Northeastern Mexico), has been carried out. The main objectives have been: (1) to establish a deposit period, and (2) to propose a reliable provenance-transport-deposit-diagenetic model. These volcano-sedimentary strata represent the altered remains of vitreous-crystalline ash (main grains: quartz + K-feldspar (sanidine) + Na-plagioclase + zircon + biotite; groundmass: glass + calcite + clinochlore + illite) deposited and preserved in a shallow, relatively large in area, open platform environment. Major and trace element geochemistry indicate that parent volcanism was mainly rhyodacitic to rhyolitic in composition. Discrimination diagrams suggest a link to continental arc transitional to extension tectonic setting. Usbnd Pb geochronology in zircon has revealed that the volcanic ash was released from their sources approximately during the range 84.6 ± 0.8 to 73.7 ± 0.3 Ma, being transported to the depocenters. Burial diagenesis process was marked by: (a) a limited recycling, (b) the partial loss of original components (mainly K-feldspar, plagioclase, biotite and glass), and (c) the addition of quartz, calcite, illite and clinochlore. The location of the source area remains uncertain, although the lack of enrichment in Zr/Sc ratio suggests that ashes were subjected to relatively fast and short-distance transport process. El Peñuelo intrusive complex, at 130-170 km west of the depocenters, is the nearest known zone of active magmatism during the Upper Cretaceous. This intermediate to felsic pluton, characterized by a geochemical affinity to post-orogenic tectonic setting, could be linked to the volcanic sources.

  12. Sedimentology of Upper Paleocene-Lower Eocene Sepultura Formation near Colonet, Baja California, Mexico

    SciTech Connect

    Miller, V.V.; Abbott, P.L.

    1988-03-01

    Upper Paleocene-lower Eocene braided-stream conglomerate of the Sepultura Formation crops out extensively within a paleovalley incised into the Cretaceous Peninsular Ranges batholith and the Alisitos Formation volcanics. The paleovalley trends just north of west as shown in 22-km long exposures within the modern San Telmo Canyon. Remnants of Sepultura fluvial-conglomerate infill reach a maximum thickness of 250 m and widths of 5-10 km. Conglomerate-clast assemblages are dominated by volcanic clasts (68-81%) along with the metamorphic (12-20%) and plutonic (2-8%) stones. The clast assemblage of andesitic and dacitic porphyries, volcaniclastics, granodiorites, aplites, and various metasediments appears to have been locally derived; all clasts are similar to the basement rocks exposed in the paleostream drainageway or just to the east of the metasedimentary belt. The Sepultura Formation contains none of the exotic, far-travelled, ultradurable rhyolitic gravels analogous to the Poway clasts that mark the time-equivalent deposits of the Mt. Soledad Formation in the San Diego area 220 km to the north. The Sepultura fluvial system supplied a gravel-rich braid delta that prograded westward over the inner shelf. Outcrops are up to 15 km wide and 23 km long, spanning braid-delta, transition-zone, and shallow-marine facies. Excellent exposures of reworked gravelly and biotite-rich sandy marine facies, some of which exhibit hummocky cross-stratification, occur in the vicinity of Punta Colonet. A late Paleocene age is indicated by the presence of turritella peninsularis. A late Paleocene age is indicated by the presence of Turritella peninsularis. A late Paleocene-early Eocene age is suggested by a sparse foraminiferal fauna (Ceratiopsos sp., Lanternosphaeridum lappaceum, Deflandrea speiosa, and Spindinium sp.).

  13. High-resolution sequence-stratigraphic correlation between shallow-marine and terrestrial strata: Examples from the Sunnyside Member of the Cretaceous Blackhawk Formation Book Cliffs eastern Utah

    SciTech Connect

    Davies, R.; Howell, J.; Boyd, R.; Flint, S.; Diessel, C.

    2006-07-15

    The Sunnyside Member of the Upper Cretaceous Blackhawk Formation in the Book Cliffs of eastern Utah provides an ideal opportunity to investigate high-resolution sequence-stratigraphic correlation between shallow-marine and terrestrial strata in an area of outstanding outcrop exposure. The thick, laterally extensive coal seam that caps the Sunnyside Member is critical for correlating between its shallow-marine and terrestrial components. Petrographic analysis of 281 samples obtained from 7 vertical sections spanning more than 30 km (18 mi) of depositional dip enabled us to recognize a series of transgressive-regressive coal facies trends in the seam. On this basis, we were able to identify a high-resolution record of accommodation change throughout the deposition of the coal, as well as a series of key sequence-stratigraphic surfaces. The stratigraphic relationships between the coal and the siliciclastic components of the Sunnyside Member enable us to correlate this record with that identified in the time-equivalent shallow-marine strata and to demonstrate that the coal spans the formation of two marine parasequences and two high-frequency, fourth-order sequence boundaries. This study has important implications for improving the understanding of sequence-stratigraphic expression in terrestrial strata and for correlating between marine and terrestrial records of base-level change. It may also have implications for improving the predictability of vertical and lateral variations in coal composition for mining and coalbed methane projects.

  14. Hints of the early Jehol Biota: important dinosaur footprint assemblages from the Jurassic-Cretaceous boundary Tuchengzi Formation in Beijing, China.

    PubMed

    Xing, Lida; Zhang, Jianping; Lockley, Martin G; McCrea, Richard T; Klein, Hendrik; Alcalá, Luis; Buckley, Lisa G; Burns, Michael E; Kümmell, Susanna B; He, Qing

    2015-01-01

    New reports of dinosaur tracksites in the Tuchengzi Formation in the newly established Yanqing Global Geopark, Beijing, China, support previous inferences that the track assemblages from this formation are saurischian-dominated. More specifically, the assemblages appear theropod-dominated, with the majority of well-preserved tracks conforming to the Grallator type (sensus lato), thus representing relatively small trackmakers. Such ichnofaunas supplement the skeletal record from this unit that lacks theropods thus far, proving a larger diversity of dinosaur faunas in that region. Sauropods are represented by medium to large sized and narrow and wide-gauge groups, respectively. The latter correspond with earlier discoveries of titanosauriform skeletons in the same unit. Previous records of ornithischian tracks cannot be positively confirmed. Purported occurrences are re-evaluated here, the trackways and imprints, except of a single possible specimen, re-assigned to theropods. Palecologically the Tuchengzi ichnofauna is characteristic of semi-arid fluvio-lacustrine inland basins with Upper Jurassic-Lower Cretaceous deposits in northern China that all show assemblages with abundant theropod and sauropod tracks and minor components of ornithopod, pterosaur and bird tracks.

  15. Hints of the Early Jehol Biota: Important Dinosaur Footprint Assemblages from the Jurassic-Cretaceous Boundary Tuchengzi Formation in Beijing, China

    PubMed Central

    Xing, Lida; Zhang, Jianping; Lockley, Martin G.; McCrea, Richard T.; Klein, Hendrik; Alcalá, Luis; Buckley, Lisa G.; Burns, Michael E.; Kümmell, Susanna B.; He, Qing

    2015-01-01

    New reports of dinosaur tracksites in the Tuchengzi Formation in the newly established Yanqing Global Geopark, Beijing, China, support previous inferences that the track assemblages from this formation are saurischian-dominated. More specifically, the assemblages appear theropod-dominated, with the majority of well-preserved tracks conforming to the Grallator type (sensus lato), thus representing relatively small trackmakers. Such ichnofaunas supplement the skeletal record from this unit that lacks theropods thus far, proving a larger diversity of dinosaur faunas in that region. Sauropods are represented by medium to large sized and narrow and wide-gauge groups, respectively. The latter correspond with earlier discoveries of titanosauriform skeletons in the same unit. Previous records of ornithischian tracks cannot be positively confirmed. Purported occurrences are re-evaluated here, the trackways and imprints, except of a single possible specimen, re-assigned to theropods. Palecologically the Tuchengzi ichnofauna is characteristic of semi-arid fluvio-lacustrine inland basins with Upper Jurassic-Lower Cretaceous deposits in northern China that all show assemblages with abundant theropod and sauropod tracks and minor components of ornithopod, pterosaur and bird tracks. PMID:25901363

  16. Paleoecology and Paleoenvironmental Interpretations of the Late Cretaceous Lower Cantwell Formation, Denali National Park, Alaska

    NASA Astrophysics Data System (ADS)

    Tomsich, C. S.; Salazar Jaramillo, S.; Jacobus, R. T.; McCarthy, P. J.; Fowell, S. J.; Fiorillo, A. R.

    2010-12-01

    The level of diversity of an ancient high-latitude fauna or flora is of interest not just for the study of species evolution and paleogeographic migration patterns, but also for the imminent response to an amplified climate change rate. Climate modelers thus focus increasingly on proxies of Polar Regions. A rich floral and faunal record indicative of a warm high-latitude paleoclimate is presently emerging from the late Campanian-Maastrichtian lower Cantwell Formation in Denali National Park, south-central Alaska. This thick (up to 4000m) alluvial fan succession was deposited during the latest accretionary phase of the Wrangellia terrane to the former southern margin of Alaska. Facies descriptions from outcrops near Sable Mountain and Polychrome Mountain record heterogeneous and laterally discontinuous lithologies characteristic of alluvial and marginal alluvial fan environments: braided channel, sandy channel, crevasse splay, sheetflood, floodplain, and lacustrine. Trace and plant fossils occur predominantly at lithological boundaries. The vertebrate fossil record encompasses tracks that can be attributed to fishes, pterosaurs, large and small non-avian theropods, birds, hadrosaurs, and ceratopsians. Hadrosaur footprints are abundant and record populations with multiple generations present. The pterosaur tracks constitute the northernmost fossil occurrence for these flying reptiles. Bird traces range from small, shore-wading bird tracks to those of a large crane-like bird. Diverse invertebrate tracks include freshwater bivalve, ostracode and gastropod trails, crayfish burrows, beetle and mole cricket tracks, wood borings and feeding traces on angiosperm leaves. Plant impression fossils represent dicotyledonous angiosperm leaves referable to nymphaealean, menispermoid, platanoid, trochodendroid and higher hamamelid groups; magnoliid seeds; diverse broad-leaved and blade-like monocot leaf fragments; the leafy shoots, leaves, cones, seeds and wood of cupressaceous and

  17. Stable-isotope stratigraphy of the Cenomanian-Turonian (Upper Cretaceous) boundary event (CTBE) in Wadi Qena, Eastern Desert, Egypt

    NASA Astrophysics Data System (ADS)

    Nagm, Emad; El-Qot, Gamal; Wilmsen, Markus

    2014-12-01

    A high-resolution δ13C isotope record from Cenomanian-Turonian boundary interval of shallow marine successions in Egypt is presented. The δ13C curves show the typical features of the globally documented Cenomanian-Turonian positive excursion, including three of the main positive isotope peaks defining the Cenomanian-Turonian Boundary Event (CTBE). Based on high-resolution ammonite biostratigraphy, the CTBE started in the study area above the Late Cenomanian Neolobites vibrayeanus Zone within the Galala Formation, directly above the global sequence boundary Cenomanian 5 (SB Ce 5). A stratigraphic gap at that level cuts out the lower a-peak of the CTBE. The Cenomanian-Turonian boundary is located within the upper part of the positive excursion between carbon excursion peaks c and d, coinciding with the boundary between the Late Cenomanian Vascoceras cauvini and the Early Turonian Vascoceratid zones. The CTBE ended up-section of peak d, at the base of the Choffaticeras spp. Zone. The amplitude of the positive δ13C excursion in Egypt is very high (reaching 6.5‰ vs. V-PDB) and largely matches curves of European standard sections and others localities from different basins. Furthermore, the Lower Turonian Holywell Isotope Event, an important marker within the lowermost Turonian, has tentatively been recognized. The positive carbon stable isotope curves presented herein represent the outreach of the oceanic anoxic event (OAE) 2 in shallow-water nearshore sequences.

  18. Allostratigraphy of the U.S. middle Atlantic continental margin; characteristics, distribution, and depositional history of principal unconformity-bounded upper Cretaceous and Cenozoic sedimentary units

    USGS Publications Warehouse

    Poag, C. Wylie; Ward, Lauck W.

    1993-01-01

    Publication of Volumes 93 and 95 ('The New Jersey Transect') of the Deep Sea Drilling Project's Initial Reports completed a major phase of geological and geophysical research along the middle segment of the U. S. Atlantic continental margin. Relying heavily on data from these and related published records, we have integrated outcrop, borehole, and seismic-reflection data from this large area (500,000 km^2 ) to define the regional allostratigraphic framework for Upper Cretaceous and Cenozoic sedimentary rocks. The framework consists of 12 alloformations, which record the Late Cretaceous and Cenozoic depositional history of the contiguous Baltimore Canyon trough (including its onshore margin) and Hatteras basin (northern part). We propose stratotype sections for each alloformation and present a regional allostratigraphic reference section, which crosses these basins from the inner edge of the coastal plain to the inner edge of the abyssal plain. Selected supplementary reference sections on the coastal plain allow observation of the alloformations and their bounding unconformities in outcrop. Our analyses show that sediment supply and its initial dispersal on the middle segment of the U. S. Atlantic margin have been governed, in large part, by hinterland tectonism and subsequently have been modified by paleoclimate, sea-level changes, and oceanic current systems. Notable events in the Late Cretaceous to Holocene sedimentary evolution of this margin include (1) development of continental-rise depocenters in the northern part of the Hatteras basin during the Late Cretaceous; (2) the appear ance of a dual shelf-edge system, a marked decline in siliciclastic sediment accumulation rates, and widespread acceleration of carbonate production during high sea levels of the Paleogene; (3) rapid deposition and progradation of thick terrigenous delta complexes and development of abyssal depocenters during the middle Miocene to Quaternary interval; and (4) deep incision of the

  19. A detailed taxonomy of Upper Cretaceous and lower Tertiary Crassatellidae in the Eastern United States; an example of the nature of extinction at the boundary

    USGS Publications Warehouse

    Wingard, G. Lynn

    1993-01-01

    Current theories on the causes of extinction at the CretaceousTertiary boundary have been based on previously published data; however, few workers have stopped to ask the question, 'How good is the basic data set?' To test the accuracy of the published record, a quantitative and qualitative analysis of the Crassatellidae (Mollusca, Bivalvia) of the Gulf and Mid-Atlantic Coastal Plains of the United States for the Upper Cretaceous and lower Tertiary was conducted. Thirty-eight species names and four generic names are used in publications for the Crassatellidae within the geographic and stratigraphic constraints of this analysis. Fourteen of the 38 species names are represented by statistically valid numbers of specimens and were tested by using canonical discriminant analysis. All 38 names, with the exception of 1 invalid name and 4 names for which no representative specimen could be located, were evaluated qualitatively. The results show that the published fossil record is highly inaccurate. Only 8 valid, recognizable species exist in the Crassatellidae within the limits of this study, 14 names are synonymized, and 11 names are represented by indeterminate molds or poorly preserved specimens. Three of the four genera are well founded; the fourth is based on the juvenile of another genus and therefore synonymized. This detailed taxonomic analysis of the Crassatellidae illustrates that the published fossil record is not reliable. Calculations of evolutionary and paleobiologic significance based on poorly defined, overly split fossil groups, such as the Crassatellidae, are biased in the following ways: Rates of evolution and extinction are higher, Faunal turnover at mass extinctions appears more catastrophic, Species diversity is high, Average species durations are shortened, and Geographic ranges are restricted. The data on the taxonomically standardized Crassatellidae show evolutionary rates one-quarter to one-half that of the published fossil record; faunal change

  20. Evidence from the lamarck granodiorite for rapid late cretaceous crust formation in California

    USGS Publications Warehouse

    Coleman, D.S.; Frost, T.P.; Glazner, A.F.

    1992-01-01

    Strontium and neodymium isotopic data for rocks from the voluminous 90-million-year-old Lamarck intrusive suite in the Sierra Nevada batholith, California, show little variation across a compositional range from gabbro to granite. Data for three different gabbro intrusions within the suite are identical within analytical error and are consistent with derivation from an enriched mantle source. Recognition of local involvement of enriched mantle during generation of the Sierran batholith modifies estimates of crustal growth rates in the United States. These data indicate that parts of the Sierra Nevada batholith may consist almost entirely of juvenile crust added during Cretaceous magmatism.

  1. Evidence from the lamarck granodiorite for rapid late cretaceous crust formation in california.

    PubMed

    Coleman, D S; Glazner, A F; Frost, T P

    1992-12-18

    Strontium and neodymium isotopic data for rocks from the voluminous 90-million-year-old Lamarck intrusive suite in the Sierra Nevada batholith, California, show little variation across a compositional range from gabbro to granite. Data for three different gabbro intrusions within the suite are identical within analytical error and are consistent with derivation from an enriched mantle source. Recognition of local involvement of enriched mantle during generation of the Sierran batholith modifies estimates of crustal growth rates in the United States. These data indicate that parts of the Sierra Nevada batholith may consist almost entirely of juvenile crust added during Cretaceous magmatism.

  2. Evidence from the lamarck granodiorite for rapid late cretaceous crust formation in california.

    PubMed

    Coleman, D S; Glazner, A F; Frost, T P

    1992-12-18

    Strontium and neodymium isotopic data for rocks from the voluminous 90-million-year-old Lamarck intrusive suite in the Sierra Nevada batholith, California, show little variation across a compositional range from gabbro to granite. Data for three different gabbro intrusions within the suite are identical within analytical error and are consistent with derivation from an enriched mantle source. Recognition of local involvement of enriched mantle during generation of the Sierran batholith modifies estimates of crustal growth rates in the United States. These data indicate that parts of the Sierra Nevada batholith may consist almost entirely of juvenile crust added during Cretaceous magmatism. PMID:17836186

  3. Back barrier facies of a microtidal coastline, Upper Cretaceous Blackhawk Formation, Utah

    SciTech Connect

    Kamola, D.L.

    1985-01-01

    Protected lagoonal environments situated landward or prograding barriers, are characterized by low energy deposits which include flood tidal deltas, flood-dominated channel-fill sandstones, swamps (coal), and lagoon-fill siltstones. Flood tidal deltas consists of landward-dipping beds of sandstone which interfinger vertically and laterally with rooted and/or bioturbated lagoonal siltstones. Locally, individual beds of the flood tidal delta may be rooted or burrowed, which indicates discontinuous deposition of sediment into a lagoon. Channel-fill sandstones characterized by landward-oriented paleocurrent directions are interpreted to represent tidally influenced channels in a flood-dominated, microtidal setting. The majority of the lagoon-fill sediments are bioturbated, rooted, or burrowed siltstone, with brackish water bivalves Crossostrea, Brachidontes, Corbula and Anomia. Trace fossils Thalassinoides, Planolites, Palaeophycus, and Pelecypodichnus are common. Ophiomorpha-burrowed, medium grain size sandstone with abraded oyster shells is the only evidence of higher energy (storm-related) lagoonal deposition. Swamps are represented by low sulfur, low ash coal seams, with tree stumps, tree roots, and dinosaur tracks. Swamp environments prograded over sediment-filled lagoons, and are interpreted as the final stage of back barrier deposition.

  4. Recognition and delineation of Paleokarst zones by the use of wireline logs in the bitumen-saturated upper Devonian Grosmont formation of Northeastern Alberta, Canada

    SciTech Connect

    Dembicki, E.A.; Machel, H.G.

    1996-05-01

    The Upper Devonian Grosmont Formation in northeastern Alberta, Canada, is a shallow-marine carbonate platform complex that was subaerially exposed for hundreds of millions of years between the Mississippian(?) and Cretaceous. During this lengthy exposure period, an extensive karst system developed that is characterized by an irregular erosional surface, meter-size (several feet) dissolution cavities, collapse breccias, sinkholes, paleosols, and fractures. The karsted Grosmont Formation, which contains giant reserves of bitumen, sub-crops beneath Cretaceous clastic sediments of the giant Athabasca tar sands deposit. The paleokarst in the Grosmont Formation can be recognized on wireline logs in relatively nonargillaceous carbonate intervals (<30 API units on the gamma-ray log) as excursions of the caliper log, off-scale neutron-density porosity readings, and severe cycle skipping of the acoustic log. The paleokarst is more prevalent in the upper units of the Grosmont Formation, and the effects of karstification decrease toward stratigraphically older and deeper units. The paleokarst usually occurs within 35 m (115 ft) of the erosional surface. The reservoir properties of the Grosmont Formation (e.g., thickness, porosity, permeability, and seal effectiveness) are significantly influenced by karstification. Depending upon the location, karstification has either benefited or degraded the reservoir characteristics. Benefits include porosity values greater than 40% (up to 100% in caverns) and permeability values of 30,000 md in severely fractured intervals. Detrimental reservoir characteristics include erosion, porosity and permeability reduction, and seal ineffectiveness.

  5. Formation of nitrogenated organic aerosols in the Titan upper atmosphere

    PubMed Central

    Imanaka, Hiroshi; Smith, Mark A.

    2010-01-01

    Many aspects of the nitrogen fixation process by photochemistry in the Titan atmosphere are not fully understood. The recent Cassini mission revealed organic aerosol formation in the upper atmosphere of Titan. It is not clear, however, how much and by what mechanism nitrogen is incorporated in Titan’s organic aerosols. Using tunable synchrotron radiation at the Advanced Light Source, we demonstrate the first evidence of nitrogenated organic aerosol production by extreme ultraviolet–vacuum ultraviolet irradiation of a N2/CH4 gas mixture. The ultrahigh-mass-resolution study with laser desorption ionization-Fourier transform-ion cyclotron resonance mass spectrometry of N2/CH4 photolytic solid products at 60 and 82.5 nm indicates the predominance of highly nitrogenated compounds. The distinct nitrogen incorporations at the elemental abundances of H2C2N and HCN, respectively, are suggestive of important roles of H2C2N/HCCN and HCN/CN in their formation. The efficient formation of unsaturated hydrocarbons is observed in the gas phase without abundant nitrogenated neutrals at 60 nm, and this is confirmed by separately using 13C and 15N isotopically labeled initial gas mixtures. These observations strongly suggest a heterogeneous incorporation mechanism via short lived nitrogenated reactive species, such as HCCN radical, for nitrogenated organic aerosol formation, and imply that substantial amounts of nitrogen is fixed as organic macromolecular aerosols in Titan’s atmosphere. PMID:20616074

  6. Lacustrine anoxic event 1 (LAE1) recorded by rock magnetism of Unit 1 of Qingshankou Formation, Late Cretaceous Songliao Basin in Northeast China

    NASA Astrophysics Data System (ADS)

    Li, H.; Zhang, S.; Zhao, K.; Wu, H.; Yang, T.

    2011-12-01

    Songliao Basin, located in northeastern China, is one of the biggest cretaceous lakes in Asia, with most completely developed cretaceous stratigraphy. Therefore, it is a key area to study cretaceous palaeontology evolution and paleoenvironmental changes. Especially, anoxic events and marine transgressional events have been the research focuses for a long time. The lacustrine anoxic event 1 (LAE1) has been reported to happen in Songliao Basin during the deposition of unit 1 of Qingshankou Formation (K2qn1). In this study, K2qn1 was sampled from China Cretaceous Continental Scientific Drilling-Songke Ι (CCSD-SK-Ι) south borehole. The K2qn1, from 1700 m to 1782.8 m in the well log, mainly consists black shale and mudstone. LAE1 is the section from 1750 m to 1775 m. Detailed rock magnetic measurements were conducted, including magnetic susceptibility (χ) and susceptibility of anhysteretic remanence (χARM), saturation isothermal remanence (SIRM), S-ratio (IRM-100mT/SIRM), medial destroyed field of ARM (MDFARM), and temperature-dependence of magnetic susceptibilities (χ/T curves), acquiring curves and reverse demagnetic curves of IRM and thermal demagnetization of ARM and SIRM and Lowrie experiment for selected samples. X-ray diffraction (XRD) was also carried out for selected samples. The acquiring curves and reverse demagnetic curves of typical specimens and the thermal demagnetization of ARM and SIRM and the Lowrie experiment confirm that the major remanence-carrier is soft magnetite. Results of χ/T curves indicate that: for some specimens, pyrite exists (Li and Zhang, 2005); for most specimens, their χ decreases slowly during heating, suggesting a dominant contribution from paramagnetic minerals. Results of XRD suggest that these paramagnetic minerals may be feldspar, kaolinite and pyrite. So paramagnetic clay minerals control χ of K2qn1; and more clay minerals may induce higher natural gamma ray (GR). Therefore, χ and GR should be positive. On the contrary

  7. Encrusting micro-organisms from the Upper Jurassic - Lower Cretaceous Inalti Carbonates (Central Pontides, Turkey): Remarks on reefal / peri-reefal facies development

    NASA Astrophysics Data System (ADS)

    Yücel Kaya, Mustafa; Altıner, Demir

    2015-04-01

    A detailed taxonomical study was carried out for the identification of encrusting micro-organisms including Bacinella-type structures, Calcistella jachenhausenensis, Crescentiella morronensis, Iberopora bodeuri, Koskinobullina socialis, Labes atramentosa, Lithocodium aggregatum, Perturbatacrusta leini, Pseudorothpletzella schmidi, Radiomura cautica, Sarsteinia babai, Terebella lapilloides and Thaumatoporella parvovesiculifera. Among these microencrusters, Perturbatacrusta leini, Iberopora bodeuri, Calcistella Jachenhausenensis, Pseudorothpletzella schmidi have been taxonomically revealed for the first time in Turkey. Within the biostratigraphic frame of the İnalti carbonates consisting of Mesoendothyra izjumiana zone (Kimmeridgian), Calcistella jachenhausenensis zone (Lower Tithonian - Upper Tithonian) and Protopeneroplis ultragranulata zone (Upper Tithonian - Berriasian), carbonate sedimentation occured in 5 depositional environments comprising slope, fore-reef, reef, back-reef and lagoonal environments. Majority of the reefal deposits of the İnalti carbonates can be classified as coral-microbial-microencruster boundstones and frequently occur associated with back-reef and fore-reef deposits within Kimmeridgian - Berriasian interval. A shallowing and a subsequent deepening in the Berriasian have been revealed by the examination of stacking patterns and vertical evolution of the microfacies. Based on the observed microfacies and general features of micro-encrusting organisms it has been concluded that İnalti Limestones share many similarities with the reefal carbonate deposits of Intra-Tethyan domain in terms of microfacies types and microencruster content. These similarities manifest the extension of the European Upper Jurassic - Lower Cretaceous reef belts to the northern Turkey.

  8. Shocked cobbles in Lower Cretaceous Duwon Formation, South Korea: A first report in Asia and their possible mechanisms

    NASA Astrophysics Data System (ADS)

    Chae, Y. U.; Kim, K. S.; Kim, C. B.; Son, M.; Lim, H. S.

    2015-12-01

    Shocked cobbles are the cobbles having shock-induced deformation structures on the surfaces. The most distinctive macroscopic features are the subparallel fractures and the pervasive surface craters, with or without radial fractures. Until now, these shocked cobbles have been reported mainly in Europe (Spain and UK) and N. America (USA and Canada), but never been found or reported in Asia. Shocked cobbles have recently found in the Lower Cretaceous Duwon Formation in South Korea, which was the first report in Asia. The Duwon Formation consists mainly of conglomerates, gravelly sandstones and intercalated mudstone and shale layers. The shocked cobbles are commonly found in the lowermost clast-supported conglomerate layers, and they show various deformation features, such as pockmarked (circular or elliptical) cobbles, cratered (Hertzian or bowl-shaped) cobbles with or without radial fractures, cobbles showing subparallel fractures, and strongly squashed or heavily dissected cobbles. In general, these deformation structures are considered to have resulted from pressure dissolution by overburden, tectonic compression, and seismic or meteorite impacts. However, the exact formation mechanism is not clearly understood, and still in debate. The shocked cobbles found in the Duwon Formation have similar features to those of previously reported shocked cobbles, especially to Triassic Buntsandstein conglomerates in northeastern Spain. Based on the macroscopic and microscopic observations, the impact shock is thought to be the best explanation for the deformation features of the Duwon Formation. However, we think that further studies are still needed to clarify the formation mechanism in detail.

  9. A new species of Ischyodus (Chondrichthyes: Holocephali: Callorhynchidae) from Upper Maastrichtian Shallow marine facies of the Fox Hills and Hell Creek Formations, Williston basin, North Dakota, USA

    USGS Publications Warehouse

    Hoganson, J.W.; Erickson, J.M.

    2005-01-01

    A new species of chimaeroid, Ischyodus rayhaasi sp. nov., is described based primarily upon the number and configuration of tritors on palatine and mandibular tooth plates. This new species is named in honour of Mr Raymond Haas. Fossils of I. rayhaasi have been recovered from the Upper Maastrichtian Fox Hills Formation and the Breien Member and an unnamed member of the Hell Creek Formation at sites in south-central North Dakota and north-central South Dakota, USA. Ischyodus rayhaasi inhabited shallow marine waters in the central part of the Western Interior Seaway during the latest Cretaceous. Apparently it was also present in similar habitats at that time in the Volga region of Russia. Ischyodus rayhaasi is the youngest Cretaceous species Ischyodus known to exist before the Cretaceous/Tertiary extinction, and the species apparently did not survive that event. It was replaced by Ischyodus dolloi, which is found in the Paleocene Cannonball Formation of the Williston Basin region of North Dakota and is widely distributed elsewhere. ?? The Palaeontological Association.

  10. Environmental-stratigraphic cross sections of the Cretaceous Fox Hills Sandstone and Hell Creek Formation and Paleocene Fort Union Formation, Richland and Roosevelt Counties, Montana

    USGS Publications Warehouse

    Flores, R.M.; Lepp, C.L.

    1983-01-01

    This study was conducted to determine the stratigraphic, lithofacies, and deopsitional relationships of the Cretaceous Fox Hills Sandstone and Hell Creek Formation and The Paleocene Fort Union Formation. These relationships, shown in sections A-A', B-B', C-C', and D-D', we established form nearly continuous exposures in the Missouri River valley in Richland and Roosevelt Counties, Mont. The river valley topography is characterized by badlands, which permitted detailed description and construction of the stratigraphic framework of the formations within a 30-mi-long belt of exposures paralleling the Missouri River. This area of study is on the western flank of the Williston Basin and east of the Poplar Dome. The latter structure imparted a northeasterly regional dip to the rocks, which averages 25 ft per mi and is as much as 100 ft per mi according to Spencer (1980). The regional dip resulted in exposure of older rocks (Cretaceous) in the west to younger rocks (Tertiary) in the east. 

  11. Soot and palynologic analysis of Manson impact-related strata (Upper Cretaceous) of Iowa and South Dakota, USA

    USGS Publications Warehouse

    Varricchio, D.J.; Raven, R.F.; Wolbach, W.S.; Elsik, W.C.; Witzke, B.J.

    2009-01-01

    The Campanian Manson impact structure of Iowa represents the best-preserved, large-diameter complex crater within the continental U.S. To assess the timing and potential mode of crater infilling and the possible presence of an impact event horizon, we analyzed samples from both within and distal to the impact structure for their elemental carbon, soot and palynomorphs. Within the impact structure, identifiable soot occurred in fragmented impact breccia and suevite but not in lower impact-melt breccia. Although most of this soot likely represents reworking of material from older Cretaceous marine shales, one high soot concentration occurs with melt material in a Keweenawan Shale-Phanerozoic clast breccia mix. This represents the first association of soot and impact-generated materials within an impact structure and the best sample candidate for Manson impact-generated soot. No palynomorphs occurred in the impact melt breccia. Overlying suevite (Keweenawan Shale clast breccia) of the central peak yielded sparse and thermally altered palynomorphs, indicating deposition prior to full cooling of the crater debris. Presence of easily degraded soot also argues for rapid backfilling of the crater. Distal samples from South Dakota represent the Sharon Springs and Crow Creek members of the Pierre Shale 230 km northwest of the Manson impact structure. Although containing shocked grains, the Crow Creek preserves no soot. In contrast, the Sharon Springs, generally considered as predating the Manson impact, has significant soot quantities. Palynomorphs differ markedly across the unconformity separating the two members with the Crow Creek containing more terrestrial forms, normapolles, and older reworked palynomorphs, consistent with a terrestrial impact to the east. Origin of the Sharon Springs soot remains unclear. Given soot occurrence within four of the five Cretaceous marine units sampled, the relatively shallow, anoxic bottom conditions of the Western Interior Cretaceous

  12. Non-marine carbonate facies, facies models and palaeogeographies of the Purbeck Formation (Late Jurassic to Early Cretaceous) of Dorset (Southern England).

    NASA Astrophysics Data System (ADS)

    Gallois, Arnaud; Bosence, Dan; Burgess, Peter

    2015-04-01

    Non-marine carbonates are relatively poorly understood compared with their more abundant marine counterparts. Sedimentary facies and basin architecture are controlled by a range of environmental parameters such as climate, hydrology and tectonic setting but facies models are few and limited in their predictive value. Following the discovery of extensive Early Cretaceous, non-marine carbonate hydrocarbon reservoirs in the South Atlantic, the interest of understanding such complex deposits has increased during recent years. This study is developing a new depositional model for non-marine carbonates in a semi-arid climate setting in an extensional basin; the Purbeck Formation (Upper Jurassic - Lower Cretaceous) in Dorset (Southern England). Outcrop study coupled with subsurface data analysis and petrographic study (sedimentology and early diagenesis) aims to constrain and improve published models of depositional settings. Facies models for brackish water and hypersaline water conditions of these lacustrine to palustrine carbonates deposited in the syn-rift phase of the Wessex Basin will be presented. Particular attention focusses on the factors that control the accumulation of in-situ microbialite mounds that occur within bedded inter-mound packstones-grainstones in the lower Purbeck. The microbialite mounds are located in three units (locally known as the Skull Cap, the Hard Cap and the Soft Cap) separated by three fossil soils (locally known as the Basal, the Lower and the Great Dirt Beds) respectively within three shallowing upward lacustrine sequences. These complex microbialite mounds (up to 4m high), are composed of tabular small-scale mounds (flat and long, up to 50cm high) divided into four subfacies. Many of these small-scale mounds developed around trees and branches which are preserved as moulds (or silicified wood) which are surrounded by a burrowed mudstone-wackestone collar. Subsequently a thrombolite framework developed on the upper part only within

  13. Calibrating Late Cretaceous Terrestrial Cyclostratigraphy with High-precision U-Pb Zircon Geochronology: Qingshankou Formation of the Songliao Basin, China

    NASA Astrophysics Data System (ADS)

    Wang, T.; Ramezani, J.; Wang, C.

    2015-12-01

    A continuous succession of Late Cretaceous lacustrine strata has been recovered from the SK-I south (SK-Is) and SKI north (SK-In) boreholes in the long-lived Cretaceous Songliao Basin in Northeast China. Establishing a high-resolution chronostratigraphic framework is a prerequisite for integrating the Songliao record with the global marine Cretaceous. We present high-precision U-Pb zircon geochronology by the chemical abrasion isotope dilution thermal-ionization mass spectrometry method from multiple bentonite core samples from the Late Cretaceous Qingshankou Formation in order to assess the astrochronological model for the Songliao Basin cyclostratigraphy. Our results from the SK-Is core present major improvements in precision and accuracy over the previously published geochronology and allow a cycle-level calibration of the cyclostratigraphy. The resulting choronostratigraphy suggest a good first-order agreement between the radioisotope geochronology and the established astrochronological time scale over the corresponding interval. The dated bentonite beds near the 1780 m depth straddle a prominent oil shale layer of the Qingshankou Formation, which records a basin-wide lake anoxic event (LAE1), providing a direct age constraint for the LAE1. The latter appears to coincide in time with the Late Cretaceous (Turonian) global sea level change event Tu4 presently constrained at 91.8 Ma.

  14. Paleoenvironmental significance of aluminum phosphate-sulfate minerals in the upper Cretaceous ooidal ironstones, E-NE Aswan area, southern Egypt

    NASA Astrophysics Data System (ADS)

    Salama, Walid

    2014-09-01

    Aluminum phosphate-sulfate (APS) minerals are present as small, disseminated crystals in the upper Cretaceous shallow marine ooidal ironstones, E-NE Aswan area, southern Egypt. Their association with the ironstones is considered as a proxy of subaerial weathering and post-diagenetic meteoric water alteration. The mineralogical composition of the ooidal ironstones was investigated by optical and scanning electron microscopes, X-ray diffraction, Fourier transform infrared and Raman spectroscopy. The ooidal ironstones are composed mainly of ooids and groundmass, both of which consist of a mixture of detrital (quartz) and diagenetic (fluorapatite, chamosite and pyrite) mineral assemblages. These mineral assemblages are destabilized under acidic and oxidizing, continental conditions. These conditions resulted from the oxidation of pyrite and probably organic matter under warm and humid, tropical climate followed the Santonian Sea regression and subaerial exposure. These pedogenic conditions promoted corrosion of quartz, dissolution of chamosite and apatite and hydrolysis of feldspars of the nearby exposed granitoids. The released Si, Al and Sr from quartz, chamosite and feldspars; Fe and S from pyrite and P, Ca and light rare earth elements (LREE) from apatite are reprecipitated as hematite, kaolinite, apatite and APS minerals from the pore fluids or along fractures. The paragenetic sequence and textural relationships of this post-diagenetic mineral assemblage indicate that hematite was formed by replacement of chamosite followed by formation of a secondary generation of pore filling chlorapatite and APS minerals and finally the precipitation of kaolinite in the remaining pore spaces. The formation of APS minerals and chlorapatite is simultaneous, but APS minerals are stable at shallow depths under acidic to neutral pH conditions, whereas chlorapatite is stable under alkaline pH conditions. Alkaline conditions were maintained at greater depths when the infiltrated

  15. Petrography and diagenesis of Lower Cretaceous Travis Peak (Hosston) Formation, east Texas

    SciTech Connect

    Dutton, S.P.

    1986-09-01

    Travis Peak sandstones in east Texas are fine to very fine-grained quartzarenites and subarkoses with an average composition of Q/sub 95/F/sub 4/R/sub 1/. Plagioclase feldspar is more abundant than orthoclase, and chert and low-rank metamorphic rock fragments are the most common lithic components. The first authigenic cements were clays, primarily illite, that coated detrital grains with tangentially oriented crystals. Next, extensive quartz cement (average 15.5% of the rock volume) occluded much of the primary porosity. Relatively late-stage cements include ankerite, which commonly has a dolomitic nucleus, a second-generation illite, and chlorite. Ankerite and dolomite are most abundant in marginal marine deposits near the top of the Travis Peak and are less abundant in the deeper, fluvial part of the formation. Feldspar dissolution and albitization of plagioclase were also relatively late diagenetic reactions. Plagioclase composition determined by microprobe ranges from An/sub 24/ to An/sub 0.1, but 83% of the analyses indicated a composition of less than An/sub 5/. Reservoir bitumen - a solid, immobile hydrocarbon accumulation - fills pores in sandstones in the upper 300 ft (90 m) of the Travis Peak. The volume of reservoir bitumen is as much as 19%. It has an H/C ratio of 0.79 to 0.90, suggesting that the bitumen formed by deasphalting of oil, which caused heavy molecules to precipitate. Permeability decreases with depth below the top of the Travis Peak. Porosimeter-measured porosity is the best predictor of permeability, and there is a low but statistically significant inverse correlation between total volume of cement and permeability.

  16. The Tendaguru formation of southeastern Tanzania, East Africa: An alternating Late Jurassic to Early Cretaceous palaeoenvironment of exceptional status

    NASA Astrophysics Data System (ADS)

    Sames, B.

    2009-04-01

    Dinosaur remains have inspired considerable scientific interest in the Tendaguru formation of southeastern Tanzania during the 20th century; however, this formation is exceptional in many other respects. The Late Jurassic to Early Cretaceous deposits of the Tendaguru formation in the southwestern Tethys are unique because they represent a marginal marine palaeoenvironment with nonmarine faunal and floral content. It is a threefold succession of marginal marine to terrestrial, carbonate-siliciclastic sediments with cyclic character, consisting of three transgressive-regressive cycles. Revisitation of the type locality (the Tendaguru, a hill approximately 60km northwest of the town of Lindi) by a German-Tanzanian expedition in summer 2000 (Heinrich et al., 2001) resulted in a new standard section (hitherto unpublished, the informal terminology is indicated by the use of lower case in Tendaguru formation), a refined environmental model (Aberhan et al., 2002) and many new insights towards its geology (with evidence of event-sedimentation, Bussert and Aberhan, 2004), biostratigraphy and a better understanding of the Tendaguru palaeo-ecosystems and the palaeoclimate. Within the scope of the designation of a new standard section at the type locality, calcareous microfossils (ostracods, charophytes) have been described to supplement the ongoing discussion about the age and palaeoecology of the Tendaguru formation (Sames, 2008). Although only a few unevenly distributed layers across the section produced calcareous microfossils, the results are very promising. A total of 40 ostracode and 2 charophyte taxa could be distinguished. The non-marine part of the ostracod fauna provides an important contribution to the documentation of Purbeck/Wealden-type nonmarine palaeoenvironments and its microfaunas and -floras previously unknown from East Africa. The marine faunal part belongs to a relatively endemic southern (Gondwana) fauna. Together with other fossil groups, the

  17. Characterisation of late Cretaceous NE-SW sinistral wrench faults in the Upper Benue Trough (Nigeria) using microtectonic and aeromagnetic data

    NASA Astrophysics Data System (ADS)

    Guiraud, M.; Ajakaiye, D. E.; Ugodulunwa, F. X. O.

    The northern section of the Cretaceous Benue Trough in Nigeria presents several major faults zones striking N 30°E to N 60°E cross-cutting both sedimentary and Precambrian basement rocks in the area. The Mesozoic deposits in the area are also deformed by the NE-SW to N 80° E trending assymetric large scale folds (Lamurde and Jarawa anticlines, Dadiya syncline). A detailed microtectonic study of the deformed tectonic zones has been carried out, mainly along the major faults zones (Gombe, Burashika, Kaltungo and Teli areas) on the sedimentary basin and on the Pan-African basement (Plateau and Gurukusa areas) surrounding the basin. At each microtectonic station a significant population of striated planes and their associated slickensides were measured. Analysis of the brittle microfaults using a computer-aided method resulted in the definition of the tectonic paleostress tensors responsible for their formation. A first brittle compression characterized by a maximum compressive stress σ 1 predominantly trending N 15° E was mainly identified along the NE-SW striking major fractures. This particular brittle tectonic event is believed to be related to the sinistral Cretaceous reactivation of Pan African NE-SW transcurrent faults. In general all the estimated stress tensors close to strike-slip tensor are characterized by a significant deflection of the direction of the maximum compressive stress σ 1 ranging from N 180° E to N 60°E. By comparing these data with microtectonic and mathematical models on strike-slip faults, the characterization of the NE-SW megafractures as sinistral strike-slip faults is particularly demonstrated. A second N 150° E compressive brittle event is also observed. The two tectonic events are documented as prevailing at the end of the Cretaceous. A structural interpretation of the total magnetic field intensity map of the study area confirms the predominance of NE-SW trends in the area. Many of these trends appear as deep magnetic

  18. A New Basal Hadrosauroid Dinosaur from the Lower Cretaceous Khok Kruat Formation in Nakhon Ratchasima Province, Northeastern Thailand

    PubMed Central

    Shibata, Masateru

    2015-01-01

    A new basal hadrosauroid dinosaur from the Lower Cretaceous Khok Kruat Formation of Thailand, Sirindhorna khoratensis gen. et sp. nov is described. The new taxon is based on composite skull and mandible including premaxilla, maxilla, jugal, quadrate, braincases, predentary, dentaries, surangular, and maxillary and dentary teeth. It is diagnostic by such characters as, sagittal crest extending along entire dorsal surface of the parietal and reaching the frontoparietal suture (autapomorphy), transversely straight frontoparietal suture, caudodorsally faced supraoccipital, no participation of the supraoccipital in the foramen magnum, mesiodistally wide leaf-shaped dentary tooth with primary and secondary ridges on the lingual surface of the crown, perpendicularly-erected and large coronoid process of dentary, and nonvisible antorbital fossa of the maxilla in lateral view. Phylogenetic analysis revealed S. khoratensis as among the most basal hadrosauroids. Sirindhorna khoratensis is the best-preserved iguanodontian ornithopod in Southeast Asia and sheds new light to resolve the evolution of basal hadrosauriforms. PMID:26716981

  19. Propeamussiidae, Inoceramidae, and other Bivalvia from the Lower Cretaceous Puez Formation (Valanginian–Cenomanian; Dolomites, South Tyrol, Italy)☆

    PubMed Central

    Schneider, Simon; Crampton, James S.; Lukeneder, Alexander

    2013-01-01

    A bivalve assemblage from the Lower Cretaceous Puez Formation at the type locality, Piz de Puez (Dolomites, South Tyrol, northern Italy) is described. Given the large amount of sedimentary rock screened during the course of this study, the <50 bivalves examined here, although occurring in very low abundance, are considered to represent a reasonably comprehensive sample. The assemblage provides insight into an autochthonous, Mesozoic, deep-water bivalve community, which was dominated by glass scallops. Two species are described as new, Parvamussium pizpuezense n. sp. and the giant P. mordsdrum n. sp. Presumably, they lived as epifaunal-reclining carnivores and preyed on various meiofauna, occupying a similar ecologic niche as their modern counterparts. Scarce epifaunal, suspension-feeding Inoceramidae entered only by occasional recruitment of larvae into an environment that is inferred to have been characterised by low levels of suspended nutrients. PMID:27087719

  20. A New Basal Hadrosauroid Dinosaur from the Lower Cretaceous Khok Kruat Formation in Nakhon Ratchasima Province, Northeastern Thailand.

    PubMed

    Shibata, Masateru; Jintasakul, Pratueng; Azuma, Yoichi; You, Hai-Lu

    2015-01-01

    A new basal hadrosauroid dinosaur from the Lower Cretaceous Khok Kruat Formation of Thailand, Sirindhorna khoratensis gen. et sp. nov is described. The new taxon is based on composite skull and mandible including premaxilla, maxilla, jugal, quadrate, braincases, predentary, dentaries, surangular, and maxillary and dentary teeth. It is diagnostic by such characters as, sagittal crest extending along entire dorsal surface of the parietal and reaching the frontoparietal suture (autapomorphy), transversely straight frontoparietal suture, caudodorsally faced supraoccipital, no participation of the supraoccipital in the foramen magnum, mesiodistally wide leaf-shaped dentary tooth with primary and secondary ridges on the lingual surface of the crown, perpendicularly-erected and large coronoid process of dentary, and nonvisible antorbital fossa of the maxilla in lateral view. Phylogenetic analysis revealed S. khoratensis as among the most basal hadrosauroids. Sirindhorna khoratensis is the best-preserved iguanodontian ornithopod in Southeast Asia and sheds new light to resolve the evolution of basal hadrosauriforms.

  1. A New Basal Hadrosauroid Dinosaur from the Lower Cretaceous Khok Kruat Formation in Nakhon Ratchasima Province, Northeastern Thailand.

    PubMed

    Shibata, Masateru; Jintasakul, Pratueng; Azuma, Yoichi; You, Hai-Lu

    2015-01-01

    A new basal hadrosauroid dinosaur from the Lower Cretaceous Khok Kruat Formation of Thailand, Sirindhorna khoratensis gen. et sp. nov is described. The new taxon is based on composite skull and mandible including premaxilla, maxilla, jugal, quadrate, braincases, predentary, dentaries, surangular, and maxillary and dentary teeth. It is diagnostic by such characters as, sagittal crest extending along entire dorsal surface of the parietal and reaching the frontoparietal suture (autapomorphy), transversely straight frontoparietal suture, caudodorsally faced supraoccipital, no participation of the supraoccipital in the foramen magnum, mesiodistally wide leaf-shaped dentary tooth with primary and secondary ridges on the lingual surface of the crown, perpendicularly-erected and large coronoid process of dentary, and nonvisible antorbital fossa of the maxilla in lateral view. Phylogenetic analysis revealed S. khoratensis as among the most basal hadrosauroids. Sirindhorna khoratensis is the best-preserved iguanodontian ornithopod in Southeast Asia and sheds new light to resolve the evolution of basal hadrosauriforms. PMID:26716981

  2. UPPER BOUND ON THE FIRST STAR FORMATION HISTORY

    SciTech Connect

    Inoue, Yoshiyuki; Madejski, Grzegorz M.; Tanaka, Yasuyuki T.; Domínguez, Alberto

    2014-02-01

    Our understanding of the nature of the extragalactic background light (EBL) has improved with the recent development of gamma-ray observation techniques. An open subject in the context of the EBL is the reionization epoch, which is an important probe of the formation history of first stars, the so-called Population III (Pop III) stars. Although the mechanisms for the formation of Pop III stars are rather well understood on theoretical grounds, their formation history is still veiled in mystery because of their faintness. To shed light on this matter, we study jointly the gamma-ray opacity of distant objects and the reionization constraints from studies of intergalactic gas. By combining these studies, we obtain a sensitive upper bound on the Pop III star formation rate density of ρ-dot {sub ∗}(z)<0.01[(1+z)/(1+7.0)]{sup 3.4}(f{sub esc}/0.2){sup −1}(C/3.0) M{sub ⊙} yr{sup −1} Mpc{sup −3} at z ≥ 7, where f {sub esc} and C are the escape fraction of ionizing photons from galaxies and the clumping factor of the intergalactic hydrogen gas. This limit is a ∼10 times tighter constraint compared with previous studies that take into account gamma-ray opacity constraints only. Even if we do not include the current gamma-ray constraints, the results do not change. This is because the detected gamma-ray sources are still at z ≤ 4.35 where the reionization has already finished.

  3. Organic geochemical characterisation of shallow marine Cretaceous formations from Yola Sub-basin, Northern Benue Trough, NE Nigeria

    NASA Astrophysics Data System (ADS)

    Sarki Yandoka, Babangida M.; Abdullah, Wan Hasiah; Abubakar, M. B.; Hakimi, Mohammed Hail; Jauro, Aliyu; Adegoke, Adebanji Kayode

    2016-05-01

    The shallow marine shales of the Cretaceous formations namely Yolde, Dukul, Jessu, Sekuliye and Numanha ranging in age from Cenomanian to Coniacian within the Yola Sub-basin in the Northern Benue Trough, northeastern Nigeria were analysed to provide an overview on their hydrocarbon generation potential. This study is based on pyrolysis analysis, total organic carbon content (TOC), extractable organic matter (EOM), biomarker distributions and measured vitrinite reflectance. The present-day TOC contents range between 0.24 and 0.71 wt. % and Hydrogen Index (HI) values between 8.7 and 113 mg HC/g TOC with Type III/IV kerogens. Based on the present-day kerogen typing, the shale sediments are expected to generate mainly gas. Biomarker compositions indicates deposition in a marine environment under suboxic conditions with prevalent contribution of aquatic organic matter and a significant amount of terrigenous organic matter input. Organic matter that is dominated by marine components contains kerogens of Type II and Type II-III. This study shows that the organic matter has been affected by volcanic intrusion and consequently, have reached post-mature stage of oil generation. These higher thermal maturities levels are consistent with the vitrinite reflectance ranging from 0.85 to 2.35 Ro % and high Tmax (440-508 °C) values as supported by biomarker maturity ratios. Based on this study, a high prospect for major gas and minor oil generation potential is anticipated from the shallow marine Cretaceous formations from Yola Sub-basin.

  4. Distribution of palaeosols and deposits in the temporal evolution of a semiarid fluvial distributary system (Bauru Group, Upper Cretaceous, SE Brazil)

    NASA Astrophysics Data System (ADS)

    Basilici, Giorgio; Bo, Patrick Führ Dal'; de Oliveira, Emerson Ferreira

    2016-07-01

    The stratigraphic and sedimentological knowledge of the Bauru Group (Upper Cretaceous, SE Brazil) is still generally insufficient and controversial. A sedimentological and palaeopedological study allowed to interpret the south-eastern portion of the Bauru Group according to the model of a fluvial distributary system. This work has two objectives: (1) to include palaeosols in the interpretation of a fluvial distributary system and (2) to give detailed information on the sedimentological and stratigraphic features of the SE portion of the Bauru Group in order to support biostratigraphical, taphonomic and palaeoecological studies. In the south-eastern portion of the Bauru Group, three genetic stratigraphic units were described and interpreted, here informally called lower, intermediate and upper units. The lower unit is constituted of muddy sandstone salt flat deposits and sandstone sheet deltas deposits and is interpreted as a basinal part of a fluvial distributary system. The intermediate unit is formed of very fine to fine-grained sandstone-filled ribbon channel and sandy sheet-shaped beds, suggesting a distal or medial portion of a fluvial distributary system. The upper unit does not match with the present models of the fluvial distributary system because mostly constituted of moderately developed, well-drained, medium- to fine-grained sandstone palaeosols, which testify pauses of sedimentation to the order of 104 years. Preserved features of sedimentary structures suggest that the parent material was formed by occasional catastrophic unconfined flows. This unit may represent the most distal portion of a fluvial distributary system generated by retrogradation of the alluvial system due to aridification of the climate. The upper unit may be interpreted also as proximal portion of fluvial distributary system if considering the coarser-grained and the well-drained palaeosols. However, the absence of channel deposits makes this interpretation unconvincing.

  5. Tectonically induced climate and its control on the distribution of depositional systems in a continental foreland basin, Cloverly and Lakota Formations (Lower Cretaceous) of Wyoming, U.S.A.

    NASA Astrophysics Data System (ADS)

    Elliott, William S.; Suttner, Lee J.; Pratt, Lisa M.

    2007-12-01

    that existed 300 to 1000 km east of the Sevier fold-and-thrust belt. Proximal to the Sevier fold-and-thrust belt, the A-interval of the Cloverly Formation and upper Ephraim Formation of the Gannett Group are typified by deposits of intermittent to ephemeral rivers and their associated floodplains. In the middle part (B-interval) of the Cloverly Formation, intermittent to ephemeral alluvial systems expand to 600 km into the basin. The upper part (C-interval) of the Cloverly Formation is characterized by playa deposits in the Bighorn and Wind River Basins and intermittent to ephemeral alluvial deposits along the front of the ancestral Sevier Mountains. Deposits of perennial to intermittent alluvial systems in the C-interval of the Cloverly and Lakota Formations are restricted to the Black Hills region, almost 900 km to the east of the Sevier Mountains. The change in the areal distribution of depositional systems through time within this continental foreland basin may be attributed to the development of a rain shadow associated with the uplift of the Sevier Mountains in the Early Cretaceous.

  6. Correlation of the Tonga Formation and the Chiwaukum Schist, North Cascades, Washington: Implications for Late Cretaceous orogenic mechanisms

    NASA Astrophysics Data System (ADS)

    Duggan, K. M.; Brown, E. H.

    1994-12-01

    The Tonga Formation of the North Cascades, Washington, consists of weakly deformed, bedded feldspathic graywacke and shale metamorphosed at chlorite to staurolite grade. Analysis of protolith lithology, Rb-Sr isotopic signature, and plutonic, metamorphic, and deformational evolution in the Tonga Formation suggests that this unit is correlative with the Chiwaukum Schist of the Cascades crystalline core. The Tonga Formation occurs on the flank of the Late Cretaceous orogen, whereas high-grade Chiwaukum Schist is exposed in the core of the orogen. Metamorphic pressure, as reflected by the distribution of metamorphic minerals and thermobarometry, increases continuously northward in the Tonga Formation from the chlorite zone (<4 kbar) to the staurolite zone (≈ 7 kbar) and then to the kyanite zone (≈ 7 kbar) in the Chiwaukum Schist. The findings reported herein do not support the previously advanced concept that the Cascades crystalline core represents the Easton blueschist terrane that was converted into higher-temperature metamorphic rock by thermal relaxation after cessation of subduction. The results of this study suggest a relatively simple two-stage metamorphic history for the Chiwaukum Schist represented by 90-93 Ma shallow contact metamorphism, overprinted by Harrovian metamorphism that increased sharply in pressure from south-west to northeast and reached peak conditions after 90 Ma, all events occurring in a plutonic/magmatic arc setting.

  7. Detailed measured sections, cross sections, and paleogeographic reconstructions of the upper cretaceous and lower tertiary nonmarine interval, Wind River Basin, Wyoming: Chapter 10 in Petroleum systems and geologic assessment of oil and gas resources in the Wind River Basin Province, Wyoming

    USGS Publications Warehouse

    Johnson, Ronald C.

    2007-01-01

    Detailed measured sections and regional stratigraphic cross sections are used to reconstruct facies maps and interpret paleogeographic settings for the interval from the base of Upper Cretaceous Mesaverde Formation to top of lower member of the Paleocene Fort Union Formation in the Wind River Basin, Wyoming. The Mesaverde Formation spans the time during which the Upper Cretaceous seaway retreated eastward out of central Wyoming in Campanian time and the initial stages of the Lewis transgression in earliest Maastrichtian time. This retreat stalled for a considerable period of time during deposition of the lower part of the Mesaverde, creating a thick buildup of marginal marine sandstones and coaly coastal plain deposits across the western part of the basin. The Lewis sea transgressed into the northeast part of Wind River Basin, beginning in early Maastrichtian time during deposition of the Teapot Sandstone Member of the Mesaverde Formation. The Meeteetse Formation, which overlies the Teapot, was deposited in a poorly-drained coastal plain setting southwest of the Lewis seaway. The Lewis seaway, at maximum transgression, covered much of the northeast half of the Wind River Basin area but was clearly deflected around the present site of the Wind River Range, southwest of the basin, providing the first direct evidence of Laramide uplift on that range. Uplift of the Wind River Range continued during deposition of the overlying Maastrichtian Lance Formation. The Granite Mountains south of the basin also became a positive feature during this time. A rapidly subsiding trough during the Maastrichtian time formed near the presentday trough of the Wind River Basin in which more than 6,000 feet of Lance was deposited. The development of this trough appears to have begun before the adjacent Owl Creek Mountains to the north started to rise; however, a muddy facies in the upper part of Lance in the deep subsurface, just to the south, might be interpreted to indicate that the

  8. Organic facies variations, source rock potential, and sea level changes in Cretaceous black shales of the Quebrada Ocal, upper Magdalena Valley, Colombia

    SciTech Connect

    Mann, U.; Stein, R.

    1997-04-01

    A 290-m-thick middle Cretaceous black shale sequence in the upper Magdalena Valley, a present-day intramontane basin located between the Central and Eastern cordilleras of Colombia, was investigated with organic-geochemical and microscopic analyses. As a result of the investigation, we were able to (1) differentiate four organic facies types, (2) estimate their source rock potential, and (3) integrated these facies into a sequence stratigraphic framework. The four organic facies types were type C, BC, B, and D. Type C contains a district terrigenous organic matter component in lowstand or highstand deposits. Organic facies type BC is characterized by an increase and a better preservation of marine organic matter. BC belongs to the lower part of the transgressive systems tract. Sediments of organic facies type B have the highest amount of marine organic matter due to excellent preservation under anoxic conditions. The absence of bioturbation and the enrichment of trace metals are further implications for deposition under anoxic conditions. Facies type B is found in the upper part of the transgressive systems tract and contains the best petroleum source rock potential. Facies B occurrence coincides with sea level highstand and correlates especially with a maximum flooding in northern South America during the Turonian. Organic facies type D is also related to highstand deposits, but shows a high rate of reworking and degradation of organic matter.

  9. Source rock potential of upper cretaceous marine shales in the Wind River Basin, Wyoming: Chapter 8 in Petroleum systems and geologic assessment of oil and gas resources in the Wind River Basin Province, Wyoming

    USGS Publications Warehouse

    Finn, Thomas M.

    2007-01-01

    /S3 ratios indicate that it is capable of generating both oil and gas. Maps showing the distribution of kerogen types and organic richness for the lower shaly member of the Cody Shale are similar to the Mowry and show that lower shaly member of the Cody is more organic rich and more oil-prone in the eastern part of the basin. Analyses of samples of the upper sandy member of the Cody Shale indicate that it has little or no potential as a source rock. Thermal maturity mapping based on vitrinite reflectance measurements in the coal-bearing post-Cody Upper Cretaceous and Paleocene rocks shows that Upper Cretaceous marine shales in the deeper parts of the Wind River Basin are thermally mature to overmature with respect to hydrocarbon generation.

  10. The Basal Nodosaurid Ankylosaur Europelta carbonensis n. gen., n. sp. from the Lower Cretaceous (Lower Albian) Escucha Formation of Northeastern Spain

    PubMed Central

    Kirkland, James I.; Alcalá, Luis; Loewen, Mark A.; Espílez, Eduardo; Mampel, Luis; Wiersma, Jelle P.

    2013-01-01

    Nodosaurids are poorly known from the Lower Cretaceous of Europe. Two associated ankylosaur skeletons excavated from the lower Albian carbonaceous member of the Escucha Formation near Ariño in northeastern Teruel, Spain reveal nearly all the diagnostic recognized character that define nodosaurid ankylosaurs. These new specimens comprise a new genus and species of nodosaurid ankylosaur and represent the single most complete taxon of ankylosaur from the Cretaceous of Europe. These two specimens were examined and compared to all other known ankylosaurs. Comparisons of these specimens document that Europelta carbonensis n. gen., n. sp. is a nodosaur and is the sister taxon to the Late Cretaceous nodosaurids Anoplosaurus, Hungarosaurus, and Struthiosaurus, defining a monophyletic clade of European nodosaurids– the Struthiosaurinae. PMID:24312471

  11. Characteristics of the Earth's Magnetic Field Prior to the Cretaceous Normal Superchron: New Paleomagnetic Results from Alto Paraguay Formation

    NASA Astrophysics Data System (ADS)

    Cervantes Solano, M.; Goguitchaichrili, A.

    2011-12-01

    We report a detailed paleomagnetic investigation from 28 lava flows (221 standard paleomagnetic cores) collected in the Paraguayan part of the Paraná Flood Basalts (Alto Paraguay Formation) in order to (i) document the variability of the Earth's magnetic field during the early Cretaceous, (ii) estimate the extrusion rate of Paraná magma and (iii) obtain a new Cretaceous paleomagnetic pole for stable South America. The paleofield direction is precisely determined for 26 sites for which, the remanent magnetization is characterized by a small within-site dispersion and a high directional stability. Nine sites give normal polarity magnetization and other 9 are reversely magnetized while 8 remaining sites show intermediate paleodirections. The mean paleomagnetic direction of normal polarity sites is I=-41.8, D=4.9, k=112, a95=4.9 while reversely magnetized sites give I=37.1, D=181.4, k=23, a95=11.1. These results point to almost antipodal mean directions, since the reversal test is positive. The mean paleomagnetic pole position obtained from 18 sites is Plong= 179.2E, Plat= 86.2S, R=17.74, k=64.56, A95=4.3. The positions of Virtual Geomagnetic Poles show a reasonably good fit with a Fisherian distribution when probability plots as well as formal testing procedures are used. The pole obtained in this study agrees reasonably well with coeval pole positions, in particular with those obtained from CPMP (Central Paraná), Los Adobes, Misiones and SAMC. However, some other similar age paleomagnetic poles show significant departure that may be attributed to local tectonic rotations or insufficient sampling to overcome the paleosecular variation. The paleosecular variation parameters are in agreement with the selected data reported for the Cretaceous Normal Superchron. In contrast, VGP angular dispersions found here are lower with respect to the Jurassic and Plio-Pleistocene data. The intermediate VGPs show a cluster in southern hemisphere of 6 VGPs located near the pacific

  12. A New Troodontid Theropod Dinosaur from the Lower Cretaceous of Utah

    PubMed Central

    Senter, Phil; Kirkland, James I.; Bird, John; Bartlett, Jeff A.

    2010-01-01

    Background The theropod dinosaur family Troodontidae is known from the Upper Jurassic, Lower Cretaceous, and Upper Cretaceous of Asia and from the Upper Jurassic and Upper Cretaceous of North America. Before now no undisputed troodontids from North America have been reported from the Early Cretaceous. Methodology/Principal Findings Herein we describe a theropod maxilla from the Lower Cretaceous Cedar Mountain Formation of Utah and perform a phylogenetic analysis to determine its phylogenetic position. The specimen is distinctive enough to assign to a new genus and species, Geminiraptor suarezarum. Phylogenetic analysis places G. suarezarum within Troodontidae in an unresolved polytomy with Mei, Byronosaurus, Sinornithoides, Sinusonasus, and Troodon + (Saurornithoides + Zanabazar). Geminiraptor suarezarum uniquely exhibits extreme pneumatic inflation of the maxilla internal to the antorbital fossa such that the anterior maxilla has a triangular cross-section. Unlike troodontids more closely related to Troodon, G. suarezarum exhibits bony septa between the dental alveoli and a promaxillary foramen that is visible in lateral view. Conclusions/Significance This is the first report of a North American troodontid from the Lower Cretaceous. It therefore contributes to a fuller understanding of troodontid biogeography through time. It also adds to the known dinosaurian fauna of the Cedar Mountain Formation. PMID:21179513

  13. Paleoenvironmental reconstruction based on palynofacies analyses of the Cansona Formation (Late Cretaceous), Sinú-San Jacinto Basin, northwest Colombia

    NASA Astrophysics Data System (ADS)

    Juliao-Lemus, Tatiana; Carvalho, Marcelo de Araujo; Torres, Diego; Plata, Angelo; Parra, Carlos

    2016-08-01

    To reconstruct the paleoenvironments of the Cansona Formation, a Cretaceous succession in Colombia that has controversial paleoenvironmental interpretation, occasionally deep marine and occasionally shallow marine, palynofacies analyses were conducted on 93 samples from four sections of the Sinú San Jacinto Basin in the north, midwest, and southwest sectors. For the palynofacies analyses, the kerogen categories were counted and subjected to cluster analyses. Four palynofacies associations were revealed for the four sections: Palynofacies Association I (PA I), which consisted of microforaminiferal linings, scolecodonts, dinoflagellate cysts, pollen grains, and fungi hyphae; PA II, which consisted of phytoclast translucent non-biostructured and biostructured, opaque phytoclasts (equidimensional and lath shaped); PA III, which consisted of pseudoamorphous particles, cuticles, resin, and fungal spores; and PA IV, which consisted of fluorescent and non-fluorescent amorphous organic matter and the fresh-water algae Botryococcus. In contrast to early studies that suggested a generalization of the depositional environment for the Cansona Formation (deep or shallow conditions), this study suggests that the formation reflects conspicuous stratigraphic and lateral changes and hence different depositional environments. The Cerro Cansona (CC4 section) and Chalán (AP section) areas are a more marine proximal settings (Early Campanian-Maastrichtian), and there is an intermediate setting for the Lorica area (SC section) and deeper conditions for the Montería area (CP2 section).

  14. Preliminary results in larger benthic foraminifera assemblage in a mixed siliciclastic-carbonate platform from the Upper Cretaceous of the External Prebetic Domain (Valencia province, SE Spain)

    NASA Astrophysics Data System (ADS)

    Robles-Salcedo, Raquel; Vicedo, Vicent

    2016-04-01

    In the External Prebetic Domain (Betic Mountain Range, Valencia province, SE Spain) it is difficult to find good outcrops to study larger benthic foraminifera (LBF), particularly in the Upper Cretaceous deposits, because of three main reasons. During the Upper Cretaceous, the complex paleogeography in the northern Prebetic Domain developed a complex system of shallow-water platforms. This is directly linked to the complexity in the distribution of the facies observed nowadays, which may change drastically in lateral, closely related outcrops having a special negative impact in the lateral extension of stratigraphical levels containing LBF. The second reason is the nature of the shallow water environments in which the larger foraminifera lived. The local continental influence derived in the establishment of very complex mixed platforms. Thus, there is not a complete register through carbonate rocks, but an alternation of microconglomerates, sandstones, calcarenites and carbonates that can be observed in the stratigraphic series of the Upper Cretaceous. This affects negatively in observing changes in the evolutionary trends of taxa. The third reason difficulting the study of LBF in northern localities of the Prebetic Domain is diagenetic. Dolomitization affects a huge part of the Mesozoic rocks deleting all fossil microfauna in the affected rocks. Such three reasons are behind the difficulty in developing correlations and having a comprehensive understanding of the biostratigraphy and phylogeny of the taxa involved. However, after several field trips developed in the northern Prebetic area, an excellent reference section for the study of the LBF in the Prebetic Domain has been identified in the surroundings of the Pinet village (Valencia province). Here, a relatively continuous section with scarce dolomitization and good conditions of accessibility exists. The larger foraminifera assemblages appering in the Pinet section will be compared with other paleobiogeographic

  15. Upper Cretaceous Ferron-Frontier clastic wedge, Utah and Wyoming - interplay between sea level, sediment supply, and subsidence

    SciTech Connect

    Ryer, T.A.

    1986-08-01

    The Ferron-Frontier clastic wedge is among the most widespread in the Cretaceous System of North America. Some writers have emphasized the role of eustatic sea level in forming this clastic wedge; others have emphasized tectonics and variations in sediment supply. The evidence indicates that both were important, but to varying degrees and at different times. The Greenhorn regression was rapid, spanning only the middle part of Turonian time. It was caused primarily by lowering of sea level. Vast tracts of the sea floor that had previously been below wave base shoaled and became areas of accumulation of sandy and/or bioclastic-rich sediments. Sea level began to rise during late Turonian time. Subwave-base conditions returned to much of the sea floor, and the shoreline transgressed westward. It was during the Niobrara trangression that uplift in the Sevier orogenic belt and within the western part of the foreland basin caused a large volume of sediment to be carried eastward through the Ferron-Frontier river systems. In southwestern Wyoming, the influx of sediment slowed the transgression and resulted in stacking of shoreline sandstone units. The influx of sediment in central Utah was even greater - so much so that the shoreline once again prograded seaward. Late Turonian time marked the peak regression of the shoreline in that area. The tectonically induced influx of sediment appears to have been short-lived. A continued rise of sea level, combined with renewed downwarping of the foreland basin and trapping of sediment within it, led to abrupt westward transgression of the shoreline during Coniacian time.

  16. Vein-filling calcites (petrography and geochemistry): Balcones fault zone, Upper Cretaceous outcrops, north-central Texas

    SciTech Connect

    Dawson, W.C.; Szymczyk, H.M.; Reaser, D.F.

    1994-09-01

    The Austin Chalk and the underlying Eagle Ford Shale are transacted by en echelon faults and fractures, associated with the Balcones fault zone, along an outcrop trend that extends from Dallas to Austin, Texas. These faults and fractures strike northeastward (N35{degrees} to 40{degrees}E) and are cemented by multiple generations of sparry calcite. Vein widths range from 0.1 to 45 cm. Slickensides, preserved on outer surfaces of calcite cements, record fault movement. Inclusions of country rock are present within calcite-filled veins, and rarely, open fracture porosity is observed in outcrop. Early calcite cements are nonferroan and later cements are ferroan calcite. Petrographic analyses indicate the occurrence of {open_quotes}fir-tree{close_quotes} zoning and fluorescent inclusions within calcite cements. Vein-filling cements have stable isotopic signatures ({delta}{sup 18}O-6.3 to -9.8{per_thousand} PDB; {delta}{sup 13}C +1.6 to +2.5{per_thousand} PDB) that are markedly depleted in {delta}{sup 13}O relative to the chalk matrix, inoceramid shells, and the estimated value for Cretaceous seawater. Trace element analyses indicate the presence of strontium (980-1600 ppm), manganese (750-1975 ppm), zinc (10-20 ppm), and copper (5-10 ppm) in the calcite cements. The negative {delta}{sup 18}O signatures of the vein-filling calcites are suggestive of precipitation from warm fluids. {delta}{sup 13}C analyses reveal that the Austin Chalk buffered the carbon incorporated into the calcite cements. These veins probably formed by a {open_quotes}crack-seat mechanism{close_quotes} whereby episodic increases in hydropressure caused fracturing. Precipitation of calcite cements within fractures is induced by subsequent decreases in pore pressure. Tectonic and diagenetic features in these outcrops provide analogs for fractured Austin Chalk reservoirs.

  17. Diagenesis of an upper Devonian carbonate-evaporite sequence: Birdbear Formation, southern interior plains, Canada

    SciTech Connect

    Whittaker, S.G.; Mountjoy, E.W.

    1996-09-01

    The Frasnian Birdbear (Nisku) Formation is a carbonate-evaporite succession formed on a shallow restricted shelf along the eastern side of the Western Canada Sedimentary Basin. Low {delta}{sup 13}C values of the shelf limestones and dolostones (1%--5%) relative to coeval open marine settings reflect the restricted paleoenvironment of the shelf. Limestones are present only in the eastern part of the study area, and were altered by meteoric and burial diagenesis and do not retain marine {delta}{sup 18}O values. {delta}{sup 18}O values of replacement dolomites have limited range ({minus}3%--5%) and may indicate dolomitization by hypersaline marine waters having low {delta}{sup 18}O values. {sup 87}Sr/{sup 86}Sr ratios of the replacement dolomites are variable (0.7082--0.7085), but also suggest that reflux of Late Devonian seawater, possibly Famennian, was the principal dolomitizing mechanism in the Birdbear shelf. Most bedded anhydrites have {delta}{sup 34}S values (22% to 24% CDT) and {sup 87}Sr/{sup 86}Sr ratios (ca. 0.7081) that record Frasnian seawater. Dissolution and reprecipitation of sedimentary sulfates resulted in sulfate cements having up to 2% higher {delta}{sup 34}S values and slightly higher {sup 87}Sr/{sup 86}Sr ratios (ca. 0.7083). Fluids associated with anhydrite dissolution may have been derived from the overlying Famennian shelf. Late diagenetic cements in the Birdbear Shelf precipitated during the Late Cretaceous and early Tertiary during maximum burial from hot, evolved residual evaporitic brines. Residual evaporitic brines that originated on the shallow eastern Upper Devonian shelves were likely important agents of diagenesis throughout the basin.

  18. Upper Cretaceous to Holocene magmatism and evidence for transient Miocene shallowing of the Andean subduction zone under the northern Neuquén Basin

    USGS Publications Warehouse

    Kay, Suzanne M.; Burns, W. Matthew; Copeland, Peter; Mancilla, Oscar

    2006-01-01

    Evidence for a Miocene period of transient shallow subduction under the Neuquén Basin in the Andean backarc, and an intermittent Upper Cretaceous to Holocene frontal arc with a relatively stable magma source and arc-to-trench geometry comes from new 40Ar/39Ar, major- and trace-element, and Sr, Pb, and Nd isotopic data on magmatic rocks from a transect at ∼36°–38°S. Older frontal arc magmas include early Paleogene volcanic rocks erupted after a strong Upper Cretaceous contractional deformation and mid-Eocene lavas erupted from arc centers displaced slightly to the east. Following a gap of some 15 m.y., ca. 26–20 Ma mafic to acidic arc-like magmas erupted in the extensional Cura Mallín intra-arc basin, and alkali olivine basalts with intraplate signatures erupted across the backarc. A major change followed as ca. 20–15 Ma basaltic andesite–dacitic magmas with weak arc signatures and 11.7 Ma Cerro Negro andesites with stronger arc signatures erupted in the near to middle backarc. They were followed by ca. 7.2–4.8 Ma high-K basaltic to dacitic hornblende-bearing magmas with arc-like high field strength element depletion that erupted in the Sierra de Chachahuén, some 500 km east of the trench. The chemistry of these Miocene rocks along with the regional deformational pattern support a transient period of shallow subduction that began at ca. 20 Ma and climaxed near 5 Ma. The subsequent widespread eruption of Pliocene to Pleistocene alkaline magmas with an intraplate chemistry in the Payenia large igneous province signaled a thickening mantle wedge above a steepening subduction zone. A pattern of decreasingly arc-like Pliocene to Holocene backarc lavas in the Tromen region culminated with the eruption of a 0.175 ± 0.025 Ma mafic andesite. The northwest-trending Cortaderas lineament, which generally marks the southern limit of Neogene backarc magmatism, is considered to mark the southern boundary of the transient shallow subduction zone.

  19. Strontium isotopes correlation of the Tunisian Late Cretaceous Abiod Formation: Comparison to previous biostratigraphic assignments

    NASA Astrophysics Data System (ADS)

    Mabrouk El Asmi, Amina

    2015-11-01

    The Tunisian topmost Le Kef Formation and Abiod Formation were the focus of strontium isotopes numeric age dating. A representative outcrop section in NW Tunisia near Le Kef town (El Djebil section) constituted the main study material. In addition, a small outcrop section (Kodiet ez Zarbia) in NW Tunisia, equivalent of the base of the overlying El Haria Formation, was also examined. Results were compared to previous numeric dating by Mabrouk et al. (2005) of the Aleg (lateral equivalent of Le Kef Formation), Abiod and El Haria formations in four offshore wells from the Miskar Gas Field (Miskar W1, W2, W3, and W4), Gulf of Gabes, SE Tunisia. Strontium isotopes stratigraphy, overall, supports the previous biostratigraphic assignments and indicates that: (i) the age ranges of the Abiod Formation at El Djebil section and in the Miskar Field are very similar; (ii) the age of the Le Kef Formation at El Djebil section is younger than its equivalent Aleg Formation in the Miskar Field; (iii) the El Haria Formation, cored in Miskar W3 and sampled at Kodiet ez Zarbia, is of approximately the same age. The strontium isotopes dating concurs with biostratigraphic assignments and suggest that the Abiod Formation in Miskar W1 (SE) corresponds to most of that occurring at El Djebil section (NW) and is therefore a condensed chalk sequence that was deposited through Campanian-Early Maastrichtian time.

  20. The late cretaceous Donlin Creek gold deposit, Southwestern Alaska: Controls on epizonal ore formation

    USGS Publications Warehouse

    Goldfarb, R.J.; Ayuso, R.; Miller, M.L.; Ebert, S.W.; Marsh, E.E.; Petsel, S.A.; Miller, L.D.; Bradley, D.; Johnson, Chad; McClelland, W.

    2004-01-01

    The Donlin Creek gold deposit, southwestern Alaska, has an indicated and inferred resource of approximately 25 million ounces (Moz) Au at a cutoff grade of 1.5 g/t. The ca. 70 Ma deposit is hosted in the Late Cretaceous Kuskokwim flysch basin, which developed in the back part of the are region of an active continental margin, on previously accreted oceanic terranes and continental fragments. A hypabyssal, mainly rhyolitic to rhyodacitic, and commonly porphyritic, 8- ?? 3-km dike complex, part of a regional ca. 77 to 58 Ma magmatic arc, formed a structurally competent host for the mineralization. This deposit is subdivided into about one dozen distinct prospects, most of which consist of dense quartz ?? carbonate veinlet networks that fill north-northeast-striking extensional fractures in the northeast-trending igneous rocks. The sulfide mineral assemblage is dominated by arsenopyrite, pyrite, and, typically younger, stibnite; gold is refractory within the arsenopyrite. Sericitization, carbonatization, and suffidation were the main alteration processes. Fluid inclusion studies of the quartz that hosts the resource indicate dominantly aqueous ore fluids with also about 3 to 7 mol percent CO2 ?? CH4 and a few tenths to a few mole percent NaCl + KCl. The gold-bearing fluids were mainly homogeneously trapped at approximately 275?? to 300??C and at depths of 1 to 2 km. Some of the younger stibnite may have been deposited by late-stage aqueous fluids at lower temperature. Measured ??18O values for the gold-bearing quartz range between 11 and 25 per mil; the estimated ??18O fluid values range from 7 to 12 per mil, suggesting a mainly crustally derived fluid. A broad range of measured ??D values for hydrothermal micas, between -150 and -80 per mil, is suggestive of a contribution from devolatilization of organic matter and/or minor amounts of mixing with meteoric fluids. Gold-associated hydrothermal sulfide minerals are characterized by ??34S values mainly between -16 and

  1. Formation of hydrocarbons under upper mantle conditions: experimental view

    NASA Astrophysics Data System (ADS)

    Kolesnikov, Anton; Kutcherov, Vladimir G.

    2010-05-01

    Main postulates of the theory of abiogenic abyssal origin of petroleum have been developed in the last 50 years in Russia and Ukraine. According to this theory, hydrocarbon compounds were generated in the mantle and migrated through the deep faults into the Earth's crust. There they formed oil and gas deposits in any kinds of rocks and in any kind of their structural positions. Until recently the main obstacle to accept the theory was the lack of reliable and reproducible experimental data confirming the possibility of the synthesis of complex hydrocarbon systems under the mantle conditions. The results received in the last decade by different groups of researchers from Russia, U.S.A. and China have confirmed the possibility of generation of hydrocarbons from inorganic materials, highly distributed in the Earth's mantle, under thermobaric conditions of 70-250 km: 2 - 5 GPa and 1000-1500 K. Experiments made in the CONAC chamber at pressures of 3-5 GPa and temperatures of 1000-1500 K by Kutcherov et al. [1, 2] have demonstrated that the mixtures of hydrocarbons with composition similar to natural hydrocarbon systems have been received as a result of chemical reactions between CaCO3, FeO and H2O. Methane formation from the same compounds was registered after heating up to 600-1500 K at pressures of 4-11 GPa in diamond anvil cells [4, 5, 6]. Influence of oxidation state of carbon donor and cooling rate of the fluid synthesized at high pressure were studied using different types of high pressure equipments. It was shown that composition of the final hydrocarbon mixture depends on these parameters. Experimental investigations of transformation of methane and ethane at 2-5 GPa and 1000-1500 K [3] confirmed thermodynamic stability of heavy hydrocarbons in the upper mantle and showed the possibility of hydrocarbon chain growth even at oxidative environment. For development of the theory of abiogenic abyssal origin of petroleum it is necessary to arrange a set of new

  2. Map showing contours on top of the upper Cretaceous Mowry Shale, Powder River basin, Wyoming and Montana

    USGS Publications Warehouse

    Crysdale, B.L.

    1991-01-01

    This map is one in a series of U.S. Geological Survey Miscellaneous Field Studies (MF) maps showing computer-generated structure contours, isopachs, and cross sections of selected formations in the Powder River basin, Wyoming and Montana. The map and cross sections were constructed from information stored in a U.S. Geological Survey Evolution of Sedimentary Basins data base. This data base contains picks of geologic formation and (or) unit tops and bases determined from electric resistivity and gamma-ray logs of 8,592 wells penetrating Tertiary and older rocks in the Powder River basin. Well completion cards (scout tickets) were reviewed and compared with copies of all logs, and formation or unit contacts determined by N. M. Denson, D.L. Macke, R. R. Schumann and others. This isopach map is based on information from 4,926 of these wells that penetrate the Minnelusa Formation and equivalents.

  3. A preliminary study of the calcite beef found in the Cretaceous Jinju Formation, Gyeongsang Basin, South Korea

    NASA Astrophysics Data System (ADS)

    Ha, S.; Chae, Y. U.; Son, M.; Jeong, G. Y.; Paik, I. S.; Lim, H. S.

    2015-12-01

    The term "beef" refers to fibrous minerals in bedding-parallel veins, where the fibers are approximately perpendicular to the vein margins (Cobbold et al., 2013). It mostly appears within organic-rich black shale layers in sedimentary basin. Although the veins can consist of white gangue minerals, such as calcite, gypsum, or quartz, the commonest mineral in the fibers is calcite. According to the worldwide localities of calcite beef compiled by Cobbold et al (2012), they concentrated in some areas, especially around the Atlantic Ocean. However, they have been rarely reported in the western Pacific margin, except Australia and New Zealand. Recently, calcite beefs have been found in the Cretaceous Jinju Formation, Gyeongsang Basin, Korea. As far as we know, this is the first report of calcite beef in Korea. The lacustrine Jinju Formation is about 1,200 m thick, and made up mainly of lacustrine dark grey to black mudstones. In the study area, calcite beefs were commonly found in the organic-rich black shale layers. The vein thickness is anywhere between a few millimeters to maximum 3 centimeters, and their length ranges from a few centimeters to several tens of meters. The interval between successive veins is from a few centimeters to about 1 meter. Most of them occur parallel to the bedding planes, although some of them are developed along fault planes or within deformed layers. In case of relatively thick beefs, the center of veins often shows a dark grey to black central median line, defined by fine-grained calcite grains, fluid inclusion lines, or wall rock particles. Based on the orientation of fibrous calcite, they can be divided into two types: straight and sigmoidal types. The fibrous calcites are thought to have been symmetrically grown from the median lines to top and bottom of wall rock. The formation mechanism of horizontal fractures, and the formation temperature of beefs in the study area remain as a matter to be studied further.

  4. Implications for the Upper Cycladic Unit: petrological, mineralogical and structural study of intrusive rocks from the Late-Cretaceous volcanic-arc in Anafi Island, Cyclades, Greece

    NASA Astrophysics Data System (ADS)

    Koutsovitis, P.; Soukis, K.; Lozios, S.

    2012-04-01

    Anafi Island is located at the southeastern edge of the Attic-Cycladic complex and is one of the few Cycladic islands composed solely by upper plate units, which are now found in the form of scattered relics in the central Aegean. The structure of the island consists of a series of thrust sheets which include from bottom to top: a non-metamorphosed flysch of partly Eocene age; greenschist facies metabasites; massive to plate amphibolites; a sequence of upper amphibolite facies meta-sediments and ophiolitic rocks, intruded by intermediate magmatic rocks; marbles and large bodies of felsic intrusive magmatic rocks. The age of the intrusive rocks within the two uppermost thrust sheets is late Cretaceous, (~85 Ma[1]). Mineral chemistry analyses of the intermediate and felsic rocks show that they include quartz, plagioclases (andesines, oligoclases and rarely labradorites), K-feldspars, amphiboles (magnesiohornblendes rarely tremolite), and biotite. The presence of quartz and biotite increases in the most felsic rocks while hornblendes less often appear. These rocks present subophitic textural features, between amphiboles and plagioclases, but also granitic textures in rocks where quartz is in a relatively high modal percentage. Structural observations reveal minor or no ductile deformation (rare undulose extinction in quartz). Based on CIPW and whole-rock chemistry results intrusive rocks are classified as quartz monzodiorites and granodiorites of calc-alkaline affinity[2]. They present subparallel REE patterns, enriched in LREE [(La/Yb)CN=6.1-20.3], with slight to moderate negative Eu anomalies (EuCN/Eu*=0.75-0.97). Their primitive mantle normalized patterns are also subparallel, enriched in LILE elements, such as Cs, Rb, Ba and K. Their Nb and Ta normalized values are lower than the normalized Th, U, K and La. Positive anomalies are noticed for Pb, negative for Ti and slightly negative to none for Zr. These features, along with their high Th/Yb ratios relative to Nb

  5. Chapter 4: The GIS Project for the Geologic Assessment of Undiscovered Oil and Gas in the Upper Cretaceous Navarro and Taylor Groups, Western Gulf Province, Texas

    USGS Publications Warehouse

    Biewick, Laura R.H.

    2006-01-01

    A geographic information system (GIS) focusing on the Upper Cretaceous Navarro and Taylor Groups in the Gulf Coast region was developed as a visual-analysis tool for the U.S. Geological Survey's 2003 assessment of undiscovered, technically recoverable oil and natural gas resources in the Western Gulf Province. The Central Energy Resources Team of the U.S. Geological Survey has also developed an Internet Map Service to deliver the GIS data to the general public. This mapping tool utilizes information from a database about the oil and natural gas endowment of the United States - including physical locations of geologic and geographic data - and converts the data into visual layers. Portrayal and analysis of geologic features on an interactive map provide an excellent tool for understanding domestic oil and gas resources for strategic planning, formulating economic and energy policies, evaluating lands under the purview of the Federal Government, and developing sound environmental policies. Assessment results can be viewed and analyzed or downloaded from the internet web site.

  6. Dynamic depositional and early diagenetic processes in a deep-water shelf setting, upper cretaceous Austin Chalk, North Texas

    SciTech Connect

    Hovorka, S.D.; Nance, H.S.

    1994-12-31

    The Austin Chalk of north Texas was deposited on a deep-water shelf north of the Sea Marcos Platform during a worldwide Coniacian and Santonian sea-level highstand. Transgressive (lowermost lower Austin Chalk), highstand (uppermost lower Austin Chalk), and regressive (middle and upper Austin Chalk) phases of cyclic chalk and marl sedimentation are recognized in excavations and tunnels created in Ellis County for the Superconducting Super Collider provide new evidence of sediment transport during Austin Chalk deposition. During transgression, bottom currents syndepositionally reworked nannoplankton oozes, incising channels as much as 120 ft across and 8 ft deep. Weakly burrowed channel fills having preservation of fine lamination document rapid infilling. Channel fills are composed of pyritized and carbonized wood and Inoceramus lag deposits, pellets, echinoderm fragments, and globigerinid grainstones, and coccolith ooze. During maximum highstand, bottom reworking was suppressed. Detrital content of highstand marls is low (>20 percent); organic content is high (1.4 to 3.5 percent). Coccolith preservation is excellent because of minimal diagenetic alteration. Regression is marked by resumed channel cutting and storm-bed winnowing in the middle and upper Austin Chalk. Suppressed resistivity log response and recessive weathering characteristics of the middle Austin Chalk are not primarily related to depositional environment but rather to increased input of volcanic ash during the accumulation of this interval. Early stabilization of ash produced clay-coated microfabrics in sediments that are otherwise similar to the transgressive deposits.

  7. Stylolites in the Upper Smackover Formation of north Louisiana

    SciTech Connect

    Denham, M.E.; Tieh, T.T. )

    1990-05-01

    Stylolites may be more intimately related to the late stages of diagenesis in carbonate rocks than previously believed. Petrographic and fission track studies of stylolites in subsurface cores of upper Smackover rocks suggest that some of these features may have acted as conduits for late-stage pore fluids and thus have played an active role in the late-stage diagenesis of these rocks. Stylolites are abundant in the rocks studied, ranging in size from microstylolites - grain to grain sutures - to stylolites a millimeter thick with amplitudes of a centimeter or more. In some of the coarser grainstones, networks of microstylolites have formed that eventually connect to larger stylolites. Late-stage authigenic phases are present within many of the stylolites. In some stylolites the high abundance of pyrite requires that some was precipitated during or after stylolite formation. Likewise, sphalerite, a common late-stage authigenic mineral, is present in some stylolites. Dolomite rhombs and anhydrite are also associated with stylolites in these samples. The occurrence of anhydrite is suggestive of late-stage fluid flow along stylolites. Anhydrite replaces the dolomite rhombs, as well B micritized grains within and around stylolites. The degree of the replacement varies from a few anhydrite crystals along a stylolite to large (several centimeters) anhydrite nodules containing traces of dolomite and stylolite-filling organics. Fission-track studies reveal that uranium is enriched in stylolite compared to their host rocks. Fission-track densities of two stylolite show their minimum uranium concentrations to be 35 and 60 ppm respectively, compared to host rock concentrations of 1-3 ppm. This enrichment of uranium may result from the migration along stylolites of uranium-rich fluids associated with hydrocarbon maturation.

  8. Geological and geochemical characterization of the Lower Cretaceous Pearsall Formation, Maverick Basin, south Texas: A future shale gas resource?

    USGS Publications Warehouse

    Hackley, Paul C.

    2012-01-01

    As part of an assessment of undiscovered hydrocarbon resources in the northern Gulf of Mexico onshore Mesozoic section, the U.S. Geological Survey (USGS) evaluated the Lower Cretaceous Pearsall Formation of the Maverick Basin, south Texas, as a potential shale gas resource. Wireline logs were used to determine the stratigraphic distribution of the Pearsall Formation and to select available core and cuttings samples for analytical investigation. Samples used for this study spanned updip to downdip environments in the Maverick Basin, including several from the current shale gas-producing area of the Pearsall Formation.The term shale does not adequately describe any of the Pearsall samples evaluated for this study, which included argillaceous lime wackestones from more proximal marine depositional environments in Maverick County and argillaceous lime mudstones from the distal Lower Cretaceous shelf edge in western Bee County. Most facies in the Pearsall Formation were deposited in oxygenated environments as evidenced by the presence of biota preserved as shell fragments and the near absence of sediment laminae, which is probably caused by bioturbation. Organic material is poorly preserved and primarily consists of type III kerogen (terrestrial) and type IV kerogen (inert solid bitumen), with a minor contribution from type II kerogen (marine) based on petrographic analysis and pyrolysis. Carbonate dominates the mineralogy followed by clays and quartz. The low abundance and broad size distribution of pyrite are consistent with the presence of oxic conditions during sediment deposition. The Pearsall Formation is in the dry gas window of hydrocarbon generation (mean random vitrinite reflectance values, Ro = 1.2–2.2%) and contains moderate levels of total organic carbon (average 0.86 wt. %), which primarily resides in the inert solid bitumen. Solid bitumen is interpreted to result from in-situ thermal cracking of liquid hydrocarbon generated from original type II kerogen

  9. Chapter 2. Assessment of undiscovered conventional oil and gas resources--Upper Jurassic-Lower Cretaceous Cotton Valley group, Jurassic Smackover interior salt basins total petroleum system, in the East Texas basin and Louisiana-Mississippi salt basins provinces.

    USGS Publications Warehouse

    Dyman, T.S.; Condon, S.M.

    2006-01-01

    The Jurassic Smackover Interior Salt Basins Total Petroleum System is defined for this assessment to include (1) Upper Jurassic Smackover Formation carbonates and calcareous shales and (2) Upper Jurassic and Lower Cretaceous Cotton Valley Group organic-rich shales. The Jurassic Smackover Interior Salt Basins Total Petroleum System includes four conventional Cotton Valley assessment units: Cotton Valley Blanket Sandstone Gas (AU 50490201), Cotton Valley Massive Sandstone Gas (AU 50490202), Cotton Valley Updip Oil and Gas (AU 50490203), and Cotton Valley Hypothetical Updip Oil (AU 50490204). Together, these four assessment units are estimated to contain a mean undiscovered conventional resource of 29.81 million barrels of oil, 605.03 billion cubic feet of gas, and 19.00 million barrels of natural gas liquids. The Cotton Valley Group represents the first major influx of clastic sediment into the ancestral Gulf of Mexico. Major depocenters were located in south-central Mississippi, along the Louisiana-Mississippi border, and in northeast Texas. Reservoir properties and production characteristics were used to identify two Cotton Valley Group sandstone trends across northern Louisiana and east Texas: a high-permeability blanket-sandstone trend and a downdip, low-permeability massive-sandstone trend. Pressure gradients throughout most of both trends are normal, which is characteristic of conventional rather than continuous basin-center gas accumulations. Indications that accumulations in this trend are conventional rather than continuous include (1) gas-water contacts in at least seven fields across the blanket-sandstone trend, (2) relatively high reservoir permeabilities, and (3) high gas-production rates without fracture stimulation. Permeability is sufficiently low in the massive-sandstone trend that gas-water transition zones are vertically extensive and gas-water contacts are poorly defined. The interpreted presence of gas-water contacts within the Cotton Valley

  10. Paleoweathering features in the Sergi Formation (Jurassic-Cretaceous), northeastern Brazil, and implications for hydrocarbon exploration

    NASA Astrophysics Data System (ADS)

    Pierini, Cristina; Mizusaki, Ana M.; Pimentel, Nuno; Faccini, Ubiratan F.; Scherer, Claiton M. S.

    2010-03-01

    Paleoweathering in the Sergi Formation has been classified and analyzed to ascertain its origin and relationship with stratigraphic evolution. The Sergi Formation belongs to the pre-rift sequence of the Recôncavo Basin (northeastern Brazil) and comprises a complex association of eolian and fluvial sandstones and lacustrine mudstones. This formation can be subdivided into three depositional sequences bounded by regional unconformities. Four paleoweathering types, each one related to a distinct origin, have been described in the Sergi Formation: (1) textural mottling, which is distinguished by alternating rock colors as a result of the iron oxide mobilization within mineral phases that evolved under alternating oxidation (yellowish, brownish and reddish shades) and reduction (grayish or greenish hues) conditions; (2) non-textural mottling, which displays a discoloration pattern that is independent of the original rock texture; (3) carbonate concentrations, usually related to carbonate nodule formation, which display a massive internal structure that reveals their origin through continuous growth or crystallization; and (4) banded carbonates (silicified), associated with the beginning of regular surface formation due to the chemical precipitation of carbonates within lacustrine environments. Both mottling color motifs and carbonate accumulation usually represent groundwater oscillation rather than pedogenesis. Only carbonate intraclasts and banded carbonate (silicified) have their origin ascribed to pedogenesis sensu stricto, although the carbonate intraclasts do not represent soil deposits in situ, but calcretes eroded from areas close to channels, and the banded carbonates (silicified) have strong diagenetic modifications. Therefore, it is reasonable to assume that fluvial and meteoric water have controlled paleoweathering evolution as well as deposition, yet both aspects are ruled by the same mechanisms (relief, sedimentation rate and, above all, climate).

  11. Extent and impact of Cretaceous magmatism on the formation and evolution of Jurassic oceanic crust in the western Pacific

    NASA Astrophysics Data System (ADS)

    Feng, H.; Lizarralde, D.; Tominaga, M.; Hart, L.; Tivey, M.; Swift, S. A.

    2015-12-01

    Multi-channel seismic (MCS) images and wide-angle sonobuoy data acquired during a 2011 cruise on the R/V Thomas G. Thompson (TN272) show widespread emplacement of igneous sills and broadly thickened oceanic Layer 2 through hundreds of kilometers of oceanic crust in one of the oldest ocean basins in the western Pacific, a region known as the Jurassic Quiet Zone (JQZ). Oceanic crust from the JQZ has grown through at least two main magmatic phases: It was formed by mid-ocean ridge processes in the Jurassic (at ~170 Ma), and then it was added to by a substantial Cretaceous magmatic event (at ~75-125 Ma). The scale of Cretaceous magmatism is exemplified by massive seafloor features such as the Ontong Java Plateau, Mid-Pacific Mountains, Marshall-Gilbert Islands, Marcus-Wake Seamount Chain, and numerous guyots, seamounts, and volcaniclastic flows observed throughout the region. We use seismic data to image heavily intruded and modified oceanic crust along an 800-km-long transect through the JQZ in order to examine how processes of secondary crustal growth - including magmatic emplacement, transport, and distribution - are expressed in the structure of modified oceanic crust. We also model gravity anomalies to constrain crustal thickness and depth to the Moho. Our observations suggest that western Pacific crust was modified via the following modes of emplacement: (a) extrusive seafloor flows that may or may not have grown into seamounts, (b) seamounts formed through intrusive diking that pushed older sediments aside during their formation, and (c) igneous sills that intruded sediments at varying depths. Emplacement modes (a) and (b) tend to imply a focused, pipe-like mechanism for melt transport through the lithosphere. Such a mechanism does not explain the observed broadly distributed intrusive emplacement of mode (c) however, which may entail successive sill emplacement between igneous basement and sediments thickening oceanic Layer 2 along ~400 km of our seismic line

  12. Petrologic and isotopic data from the Cretaceous (Campanian) Blackhawk Formation and Star Point Sandstone (Mesaverde Group), Wasatch Plateau, Utah

    USGS Publications Warehouse

    Fishman, Neil S.; Turner, Christine E.; Peterson, Fred

    2013-01-01

    The presence of discrete minerals associated with coal—whether (1) detrital or authigenic constituents of the coals or in thin mudstone or siltstone units interbedded with coals, or (2) authigenic phases that formed along cleats—might influence its utilization as an energy resource. The build-up of sintered ash deposits on the surfaces of heat exchangers in coal-fired power plants, due to the alteration of minerals during combustion of the coal, can seriously affect the functioning of the boiler and enhance corrosion of combustion equipment. In particular, the presence of sodium in coals has been considered a key factor in the fouling of boilers; however, other elements (such as calcium or magnesium) and the amount of discrete minerals burned with coal can also play a significant role in the inefficiency of and damage to boilers. Previous studies of the quality of coals in the Cretaceous (Campanian) Blackhawk Formation of the Wasatch Plateau, Utah, revealed that the sodium content of the coals varied across the region. To better understand the origin and distribution of sodium in these coals, petrologic studies were undertaken within a sedimentological framework to evaluate the timing and geochemical constraints on the emplacement of sodium-bearing minerals, particularly analcime, which previously had been identified in coals in the Blackhawk Formation. Further, the study was broadened to include not just coals in the Blackhawk Formation from various localities across the Wasatch Plateau, but also sandstones interbedded with the coals as well as sandstones in the underlying Star Point Sandstone. The alteration history of the sandstones in both formations was considered a key component of this study because it records the nature and timing of fluids passing through them and the associated precipitation of sodium-bearing minerals; thus, the alteration history could place constraints on the distribution and timing of sodium mineralization in the interbedded or

  13. Diagenesis and reservoir quality of the Lower Cretaceous Quantou Formation tight sandstones in the southern Songliao Basin, China

    NASA Astrophysics Data System (ADS)

    Xi, Kelai; Cao, Yingchang; Jahren, Jens; Zhu, Rukai; Bjørlykke, Knut; Haile, Beyene Girma; Zheng, Lijing; Hellevang, Helge

    2015-12-01

    The Lower Cretaceous Quantou Formation in the southern Songliao Basin is the typical tight oil sandstone in China. For effective exploration, appraisal and production from such a tight oil sandstone, the diagenesis and reservoir quality must be thoroughly studied first. The tight oil sandstone has been examined by a variety of methods, including core and thin section observation, XRD, SEM, CL, fluorescence, electron probing analysis, fluid inclusion and isotope testing and quantitative determination of reservoir properties. The sandstones are mostly lithic arkoses and feldspathic litharenites with fine to medium grain size and moderate to good sorting. The sandstones are dominated by feldspar, quartz, and volcanic rock fragments showing various stages of disintegration. The reservoir properties are quite poor, with low porosity (average 8.54%) and permeability (average 0.493 mD), small pore-throat radius (average 0.206 μm) and high displacement pressure (mostly higher than 1 MPa). The tight sandstone reservoirs have undergone significant diagenetic alterations such as compaction, feldspar dissolution, quartz cementation, carbonate cementation (mainly ferrocalcite and ankerite) and clay mineral alteration. As to the onset time, the oil emplacement was prior to the carbonate cementation but posterior to the quartz cementation and feldspar dissolution. The smectite to illite reaction and pressure solution at stylolites provide a most important silica sources for quartz cementation. Carbonate cements increase towards interbedded mudstones. Mechanical compaction has played a more important role than cementation in destroying the reservoir quality of the K1q4 sandstone reservoirs. Mixed-layer illite/smectite and illite reduced the porosity and permeability significantly, while chlorite preserved the porosity and permeability since it tends to be oil wet so that later carbonate cementation can be inhibited to some extent. It is likely that the oil emplacement occurred

  14. An abelisaurid from the Late Cretaceous of Egypt: implications for theropod biogeography.

    PubMed

    Smith, Joshua B; Lamanna, Matthew C

    2006-05-01

    Recent paleogeographic scenarios postulate the isolation of continental Africa during the Late Cretaceous. The absence of abelisaurid theropods from Upper Cretaceous African strata was offered as support of hypothesized African isolation with the acknowledgement that the paucity of African abelisaurids may be mostly an issue of sampling. Here we report on a shed theropod tooth from the Upper Cretaceous (Maastrichtian, approximately 70 Ma) Duwi Formation of Egypt. The tooth was referred to the Malagasy abelisaurid "Megalosaurus" crenatissimus (=Majungasaurus crenatissimus) in 1921. A discriminant function analysis was run to test for morphological congruence between the Egyptian tooth and the dentitions of 24 theropod taxa. The analysis correctly classified 96.6% of the teeth in the sample and assigned the tooth to Majungasaurus. As current paleogeographic reconstructions posit Madagascar had attained its current position relative to Africa before the Late Cretaceous, it is unlikely that the Egyptian tooth actually pertains to Majungasaurus. Nevertheless, its classification as an abelisaurid supports its referral to the clade. This tooth thus constitutes defensible evidence of an abelisaurid from the post-Cenomanian Cretaceous of mainland Africa. Combined with recent discoveries of abelisaurids in Niger and Morocco, the result indicates that Abelisauridae was a diverse group in Africa during the Cretaceous, existing in multiple places for at least approximately 25 Ma and weakens support for hypotheses of an isolated Africa during the Late Cretaceous. PMID:16541232

  15. An abelisaurid from the Late Cretaceous of Egypt: implications for theropod biogeography

    NASA Astrophysics Data System (ADS)

    Smith, Joshua B.; Lamanna, Matthew C.

    2006-05-01

    Recent paleogeographic scenarios postulate the isolation of continental Africa during the Late Cretaceous. The absence of abelisaurid theropods from Upper Cretaceous African strata was offered as support of hypothesized African isolation with the acknowledgement that the paucity of African abelisaurids may be mostly an issue of sampling. Here we report on a shed theropod tooth from the Upper Cretaceous (Maastrichtian, ˜70 Ma) Duwi Formation of Egypt. The tooth was referred to the Malagasy abelisaurid “ Megalosaurus” crenatissimus (= Majungasaurus crenatissimus) in 1921. A discriminant function analysis was run to test for morphological congruence between the Egyptian tooth and the dentitions of 24 theropod taxa. The analysis correctly classified 96.6% of the teeth in the sample and assigned the tooth to Majungasaurus. As current paleogeographic reconstructions posit Madagascar had attained its current position relative to Africa before the Late Cretaceous, it is unlikely that the Egyptian tooth actually pertains to Majungasaurus. Nevertheless, its classification as an abelisaurid supports its referral to the clade. This tooth thus constitutes defensible evidence of an abelisaurid from the post-Cenomanian Cretaceous of mainland Africa. Combined with recent discoveries of abelisaurids in Niger and Morocco, the result indicates that Abelisauridae was a diverse group in Africa during the Cretaceous, existing in multiple places for at least ˜25 Ma and weakens support for hypotheses of an isolated Africa during the Late Cretaceous.

  16. Lower Cretaceous-Upper Jurassic carbonate complex of southern margin of Florida-Bahama platform in northern Cuba

    SciTech Connect

    Winston, G.O.

    1988-09-01

    Examination of core samples and cuttings from seven wells in northern Cuba has shown that the southern margin of the Florida-Bahama platform is composed largely of dolomitized carbonate mound and talus material. Dolomitization is possibly due to reflux of the highly saline waters from the South Florida evaporite basin to the north. At least four separate episodes of mound construction are present, accompanied by seaward talus material. South of the dolomitized carbonate complex, three wells penetrated a deeper water continental slope facies consisting principally of light-colored limestone with uncommon beds of shale and radiolarian limestone. Zones of shallower facies appear to be intercalated. Farther to the south beyond the scope of this study, volcanics and serpentine are reported in the literature. The northernmost wells on the island are cut by one or more high-angle thrust faults. Intense crumpling and faulting are present in the deeper water facies between the continental margin complex and the oceanic volcanic-serpentine province. The intense crumpling was probably caused as the deep-water sediments were scraped off by the subduction of an oceanic plate from the south beneath the continental crust of the Florida-Bahama platform. Certain beds in the northern Cuba carbonate complex can be correlated with the standard section in Florida, as exhibited in the Cay Sal well to the north. Three anhydrite beds in the Cayo Coco well appear to correlate with thick anhydrites in the Punto Gorda, Pumpkin Bay, and Bone Island formations. In the Collazo well to the south, a limestone-anhydrite section appears to correlate with the Pumpkin Bay. Three limestone intervals in the Blanquizal well seem to correlate with portions of the Rattlesnake Hammock, Pumpkin Bay, and Bone Island formations in the Cay Sal well.

  17. Lithologic variations and diagenesis of Lower Cretaceous Muddy Formation in northern Powder River basin, Wyoming

    SciTech Connect

    Walker, A.L.; Patterson, P.E.

    1986-08-01

    Regional facies studies show that sandstones in the Muddy Formation, northern Powder River basin, were deposited in fluvial and nearshore marine paleoenvironments. Most sandstones of the fluvial facies contain only minor amounts of clay matrix and are classified as quartzarenite or sublitharenite, whereas those of the shoreface facies contain appreciable clay and are classified as litharenite or arkose. The arkoses are concentrated along a narrow belt that trends northeastward, parallel to the inferred paleoshoreline. Both the fluvial and shoreface sandstones have been variably affected by postdepositional alteration. During early stages of diagenesis, matrix clay was formed predominantly within the shoreface sandstones, owing mainly to alteration of volcanic material. Later, quartz overgrowths and calcite cement were precipitated within the remaining pore spaces in both fluvial and shoreface sandstones. Calcite also replaced detrital framework grains and some of the previously formed matrix clay. During intermediate diagenetic stages, detrital feldspar grains, particularly those in the arkosic shoreface sandstones, were replaced by albite, which characteristically lacks twinning or displays distinctive chessboard texture. Microprobe analyses indicate that both forms are essentially pure albite. During later stages of diagenesis, following maximum burial, much of the calcite was dissolved, producing secondary porosity. Inasmuch as the calcite was precipitated early, i.e., prior to significant compaction, and inasmuch as it replaced both framework grains and authigenic matrix clay, the secondary pores exhibit a relatively high level of interconnection. It is this secondary porosity that has contributed to the migration and storage of hydrocarbons in the Muddy Formation.

  18. An integrated workflow to assess the remaining potential of mature hydrocarbon basins: a case study from Northwest Germany (Upper Jurassic/Lower Cretaceous, Lower Saxony Basin)

    NASA Astrophysics Data System (ADS)

    Seyfang, Björn; Aigner, Thomas; Munsterman, Dirk K.; Irmen, Anton

    2016-06-01

    Mature hydrocarbon provinces require a high level of geological understanding in order to extend the lives of producing fields, to replace reserves through smaller targets and to reduce the risks of exploring for more and more subtle hydrocarbon traps. Despite a large number of existing wells in the area studied in this paper, the depositional environments and the stratigraphic architecture were still poorly known. In order to improve the geological understanding, we propose a workflow to assess the remaining reservoir potential of mature hydrocarbon areas, integrating cores, cuttings, well-logs, biostratigraphy and seismic data. This workflow was developed for and is exemplified with the northwest of the Lower Saxony Basin (LSB), a mature hydrocarbon province in northwest Germany, but can be applied in a similar fashion to other areas. Systematic integration of lithofacies analysis, chrono- and sequence stratigraphy, combined with electrofacies analysis and modern digital methods like neural network-based lithology determination and 3D facies modelling provides a high-resolution understanding of the spatial facies and reservoir architecture in the study area. Despite widely correlatable litho-units in the Upper Jurassic and Lower Cretaceous in the LSB, complex heterogeneous sedimentary systems can be found in the basin's marginal parts. Two new play types were determined in the study area, showing a remaining potential for stratigraphic hydrocarbon traps. The results of this exploration scale study also provide the basis for re-evaluations on a field development scale. On a basin scale, this study may encourage further data acquisition and re-evaluations to discover previously unknown reservoirs.

  19. Lower Cretaceous palynological assemblages of the Levashi Formation in the Aimaki section of Central Dagestan

    NASA Astrophysics Data System (ADS)

    Yaroshenko, O. P.; Aleksandrova, G. N.

    2015-01-01

    We present the results of the study of higher plant spores and pollen in a section of the Levashi Formation near the village of Aimaki. The Hauterivian and Barremian palynological associations were defined on the basis of changes in the taxonomic content of terrestrial plant spores and pollen. The associations are comparable with Hauterivian and Barremian assemblages of various regions of the Caucasus with respect to the composition of major groups and individual taxa. A transition in the vegetation was noted, from the coniferous palynological association of the Hauterivian to a fern association in the Barremian. The predominance of hygrophilous ferns and the presence of lycophytes and representatives of Taxodiaceae and Sphagnopsida in the Barremian (which were nearly absent in the Hauterivian), accompanied by a significant decrease in thermophilic Cheirolepidiaceae and other conifers, indicate a change in climate characterized by an increase in humidity and a decrease in temperature.

  20. Orogenic evolution of the External Dinarides in the NE Adriatic region: a model constrained by tectonostratigraphy of Upper Cretaceous to Paleogene carbonates

    NASA Astrophysics Data System (ADS)

    Korbar, Tvrtko

    2009-11-01

    Mesozoic to Cenozoic evolution of the central part of the Adriatic plate (External Dinarides and Adriatic foreland) is still a matter of debate. This is expressed by opposing paleogeographic models: single carbonate platform (Adriatic or Adriatic-Dinaridic) versus two carbonate platforms (Adriatic and Dinaridic) separated by the inter-platform Budva-Cukali basin. Estimates of shortening during Adria NE subduction, that resulted in the development of the Dinaric Alps, differ substantially. The single-platform model involves minor shortening achieved by folding and faulting along steep reverse faults. The two-platform model involves significant shortening achieved mainly by thrust stacking, which resulted in almost complete underthrusting of the intervening basinal deposits. Analysis of Upper Cretaceous to Paleogene stratigraphical data from both outcrops and boreholes allows regional correlation and the interpretation of major lithostratigraphic units. As a result, a few tectonostratigraphic units are recognized. The tectonostratigraphy is used as a basis for a new model on the late Mesozoic to Cenozoic evolution of the region. Generally, Adriatic and Dinaridic segments acted as major regional crustal entities of Adria. The upper portions of the sedimentary cover were differentially affected by progressive, southwestward verging thin-skinned deformations during the Paleocene to Eocene (Miocene?). The Adriatic foreland stayed out of the deformations, and is characterized predominantly by wrench and salt tectonics. The regional tectonic map shows arcuate thrust fronts of the External Dinarides. They could be a consequence of both, differential propagation of early-orogenic thin-skinned deformations over crustal fragments separated by transversal faults, and/or differential (isostatic?) movements of the fragments. The collision zone of the Adriatic and Dinaridic segments is characterized by late-orogenic (Oligocene to Miocene) thick-skinned compressional uplift

  1. Tectonic triggering of slump sheets in the Upper Cretaceous carbonate succession of the Porto Selvaggio area (Salento peninsula, southern Italy): Synsedimentary tectonics in the Apulian Carbonate Platform

    NASA Astrophysics Data System (ADS)

    Mastrogiacomo, G.; Moretti, M.; Owen, G.; Spalluto, L.

    2012-08-01

    Soft-sediment deformation structures crop out in the Upper Cretaceous carbonate succession in Porto Selvaggio cove in the western Salento peninsula, Apulian foreland, southern Italy. The deformed interval is about 13 m thick and occurs between shallow-water limestones and dolostones formed in peritidal and shallow subtidal environments. It comprises well-bedded grey mudstones interlayered with dark grey laminated microbioclastic wackestones characterized by couplets of closely spaced dark and bright laminae marked by the parallel orientation of calcareous microbioclasts and thin-shelled bivalves. The low biological diversity, scarcity of burrowing biota, and presence of a well preserved fish fauna provide evidence of anoxic conditions occurring in morphological depressions within the platform, and a stagnant, stratified water body affected by weak bottom currents, indicating the sudden development of a localised and short-lived intraplatform basin. Two soft-sediment deformation horizons (slump sheets) separated by undeformed limestones with similar facies occur in this part of the succession. The lower, thicker slump sheet (1.0-1.3 m thick) contains asymmetric and box folds. Well-developed décollement surfaces (locally containing thick brecciated zones) cut the folds, forming small-scale thrust-sheets and indicating mixed plastic to brittle behaviour. The upper, thinner slump sheet (0.25-0.35 m thick) contains only asymmetric folds, indicating plastic behaviour only. The differences in deformation style are attributed to differences in facies. Measurements of fold-axis orientations in the slump sheets show that they moved in similar directions, recording the development of a local, gently dipping palaeoslope. Autogenic (internal) trigger mechanisms are ruled out by a detailed consideration of facies. The slump sheets were triggered by allogenic, tectonic effects, either the weakening of sediment by seismic activity or the tectonically induced steepening of slopes

  2. Carbon-Isotope Chemostratigraphy of the Yellow Cat Member of the Cretaceous Cedar Mountain Formation, Utah

    NASA Astrophysics Data System (ADS)

    Suarez, C. A.; Hatzell, G.; Suarez, M. B.; Salazar-Verdin, J.; Al-Suwaidi, A. H.; Kirkland, J. I.

    2014-12-01

    Paleosols and lacustrine sediments of the Yellow Cat Member (YCM), Cedar Mountain Formation (CMF), Eastern Utah were collected at the "Lake Madsen" (a dominantly lacustrine section) and Doelling's Bowl (a mixed lacustrine/ palustrine/ paleosol section) and analyzed for bulk organic carbon isotopes (δ13Corg) . The YCM is thought to span the Barremian to Aptian based on dinosaur faunal assemblages. Correlation with distinct carbon isotope excursions (CIE) specifically those associated with the Selli Event or OAE 1a would allow insight into the response of terrestrial ecosystems to C-cycle perturbations during the Aptian, and may improve chronostratigraphy. Lake Madsen data ranges between a minimum of -28.5‰ and a maximum of -21.4‰ with an average of ~ -25‰ and shows a stepped negative isotope excursion of -3‰., with three distinct negative steps starting ~ 7.5 m above the Jurassic Morrison Formation and an intervening large positive excursion ~ 4.5 m from the base of the Poison Strip Sandstone (~119Ma) Member of the CMF. Doelling's Bowl data spans a longer vertical distance and ranges from a minimum of -29.0‰ to a maximum of -25.7‰, averages -27.7‰ and is somewhat cyclic in nature. δ13Corg chemostratigraphic profile for Doelling's Bowl poorly correlates to the Lake Madsen section, likely due to recycling of organic C and wet/dry cycles of the palustrine environment. Correlation of the Lake Madsen section to marine δ13CCO3 curve from Cismon Valley of the southern Alps indicates the lower Aptian C-isotope excursions C1 to C6, with the distinctive C3 negative CIE occur at the top of the Yellow Cat Member, therefore documenting a terrestrial manifestation of the CIE associated with OAE1a - Selli Event. This suggests the age of the majority of the Yellow Cat Member is Barremian to lower Aptian and the Barremian-Aptian boundary occurs at the top of the Member ~ 25cm below the base of the Poison Strip Sandstone. Further isotopic analysis of vertebrate

  3. DNA sequence from Cretaceous period bone fragments.

    PubMed

    Woodward, S R; Weyand, N J; Bunnell, M

    1994-11-18

    DNA was extracted from 80-million-year-old bone fragments found in strata of the Upper Cretaceous Blackhawk Formation in the roof of an underground coal mine in eastern Utah. This DNA was used as the template in a polymerase chain reaction that amplified and sequenced a portion of the gene encoding mitochondrial cytochrome b. These sequences differ from all other cytochrome b sequences investigated, including those in the GenBank and European Molecular Biology Laboratory databases. DNA isolated from these bone fragments and the resulting gene sequences demonstrate that small fragments of DNA may survive in bone for millions of years.

  4. Upper-greenschist facies intragrain deformation of albite in mylonitic meta-pegmatite and the influence of crystallographic anisotropy on microstructure formation

    NASA Astrophysics Data System (ADS)

    Eberlei, Tobias; Habler, Gerlinde; Grasemann, Bernhard; Abart, Rainer

    2014-12-01

    We studied the deformation behaviour of albite from Permian meta-pegmatite in Cretaceous upper-greenschist facies shear zones from the Austroalpine Matsch Unit in the Eastern Alps (Italy). Sodium-feldspars from these rocks provide excellent natural examples for studying mechanisms of intragranular deformation under mid-crustal conditions in grains with different angular relations between their (010) planes and the kinematic frame. The studied rocks were deformed at c. 500 °C in localized shear zones with well characterized top-W shear kinematics supposedly during the Cretaceous upper-greenschist facies tectonometamorphic event. Microstructural and chemical data suggest that crystallographic anisotropies in albite exert a strong control on microstructure formation and that albite primarily deformed by a combination of brittle fracturing, dissolution-precipitation and incipient crystal plasticity as a function of the orientation of the crystallographic anisotropy relative to the supposed shortening direction. Dissolution along discontinuities forming stylolites perpendicular to the shortening direction is associated with the precipitation of fine-grained albite with some compositional variability (Ab96-98 and Ab89-91) in cracks. New albite precipitates form aggregates with straight segments of high angle grain boundaries, nearly 120° dihedral angles and only a poor or no orientation relation to the hosting clast. Intragranular kinking is related to continuous lattice rotation of up to 15° by a misorientation axis close to albite [100] and the formation of subgrain boundaries with maximum misorientations of 7°. Synthetic microshear zones supposedly nucleated on pre-existing cracks, and are associated with formation of subgrain boundaries in shortening quadrants and cracks together with precipitates of potassium feldspar in extensional quadrants adjacent to the microshear zone. New microstructural and textural data from mylonitic Permian meta-pegmatites document

  5. Chapter 5. Assessment of undiscovered conventional oil and gas resources-Lower Cretaceous Travis Peak and Hosston formations, Jurassic Smackover interior salt basins total petroleum system, in the East Texas basin and Louisiana-Mississippi salt basins provinces.

    USGS Publications Warehouse

    Dyman, T.S.; Condon, S.M.

    2006-01-01

    The petroleum assessment of the Travis Peak and Hosston Formations was conducted by using a total petroleum system model. A total petroleum system includes all of the important elements of a hydrocarbon fluid system needed to develop oil and gas accumulations, including source and reservoir rocks, hydrocarbon generation, migration, traps and seals, and undiscovered accumulations. A total petroleum system is mappable and may include one or more assessment units. For each assessment unit, reservoir rocks contain similar geology, exploration characteristics, and risk. The Jurassic Smackover Interior Salt Basins Total Petroleum System is defined for this assessment to include (1) Upper Jurassic Smackover carbonates and calcareous shales and organic-rich shales of the Upper Jurassic Bossier Shale of the Cotton Valley Group and (2) Lower Cretaceous Travis Peak and Hosston Formations. The Jurassic Smackover Interior Salt Basins Total Petroleum System includes three conventional Travis Peak-Hosston assessment units: Travis Peak-Hosston Gas and Oil (AU 50490205), Travis Peak-Hosston Updip Oil (AU 50490206), and Travis Peak-Hosston Hypothetical Updip Oil (AU 50490207). A fourth assessment unit, the Hosston Hypothetical Slope-Basin Gas Assessment Unit, was named and numbered (AU 50490208) but not geologically defined or quantitatively assessed owing to a lack of data. Together, assessment units 50490205 to 50490207 are estimated to contain a mean undiscovered conventional resource of 29 million barrels of oil, 1,136 billion cubic feet of gas, and 22 million barrels of natural gas liquids.

  6. A new toothed pterosaur (Pterodactyloidea: Anhangueridae) from the Early Cretaceous Romualdo Formation, NE Brazil.

    PubMed

    Bantim, Renan A M; Saraiva, Antônio A F; Oliveira, Gustavo R; Sayão, Juliana M

    2014-10-01

    A new species of pterosaur, Maaradactylus kellneri gen. nov., sp. nov. (Archosauria: Pterosauria) from the Romualdo Formation (Aptian/Albian), is herein described. The specimen (MPSC R 2357) was found at Sítio São Gonçalo, Santana do Cariri city (State of Ceará, northeast Brazil) and consists of the skull, atlas and axis, and represents one of the largest skulls of the Anhangueridae from the Araripe Basin described. The autapomorphies of the new pterosaur include the following characters: a premaxillary sagittal crest that is relatively long and high, beginning at the anterior part of the skull (rostrum) and extending to the 22nd pair of alveoli, not covering the nasoantorbital fenestra or the choanaes, and also the presence of 35 pairs of alveoli; smooth palatal ridge, which starts on the 5th pair of alveoli and ends on the 13th pair; palate is convex shaped in the anterior region; choanae not extending laterally; small and convex palatal elevation; the 5th, 6th and 7th alveoli smaller than the 4th and 8th; the alveoli decreasing in size from the 9th to the 12th and increasing from the 13th to 18th, and from the 18th to the 35th they are arranged in triplets. Furthermore, the lateral surface of the premaxillary crest shows grooves and tridimensional structures that may have housed blood vessels.

  7. Lower Cretaceous barrier reef and outer shelf facies, Sligo Formation, south Texas

    SciTech Connect

    Kirkland, B.L.; Lighty, R.G.; Rezak, R.; Tieh, T.T.

    1987-09-01

    Along the south Texas margin, a vast carbonate-shelf complex with an extensive barrier-reef system and abundant shallow-lagoon and skeletal-shoal deposits existed during the Aptian to Albian. The Sligo Formation represents more than 609.6 m (2000 ft) of deposition along this margin. Facies types along the shelf edge were quantitatively delineated by cluster analysis of detailed point-count data from 90 thin sections of whole cores from five wells. In addition, studies of 42.6 m (140 ft) of core slabs and thin sections of well cuttings from four other wells were used to establish a regional depositional model. Along the Sligo shelf edge, three major facies occur: reef or reef rubble (two subfacies), back reef (three subfacies), and lagoonal (two subfacies). Reef facies are dominated by caprinids and also contain solenoporid algae, stromatoporoids, and an assortment of corals. Behind the reef, a spectrum of extensive back-reef deposits interfinger with shallow (< 5 m), lagoonal sediments. Farther behind the shelf-margin reef complex, along the outer shelf, benthic foraminifera, peloids, and ooids were deposited in high-energy shoals, and are interbedded with low-energy lagoonal sediments. The two types of buildups probably existed along the Sligo shelf margin and the equivalent Cupido shelf margin to the south: (1) wave-resistant coral-caprinid-stromatoporid barrier reefs (adjacent to restricted lagoonal facies), and (2) low-lying rudist banks (adjacent to diverse, washed lagoonal facies).

  8. Effects of climate, tectonism, and variations in sea level on formation of Cretaceous coals of North America

    SciTech Connect

    McCabe, P.J.; Brownfield, M.E.; Hansen, D.E.; Hettinger, R.D.; Kirschbaum, M.A.; Sanchez, D.

    1988-07-01

    Extensive deposits of Cretaceous coal-bearing strata are present in western North America, extending from the North Slope of Alaska to northern Mexico. Most of the Cretaceous sediments were derived from the active Cordillera region and were deposited in foreland basins on the western margin of the Western Interior seaway. A multidisciplinary study is in progress to document and attempt to explain the temporal and spatial distribution of the Cretaceous coals. The study examines the effects of variations of paleoclimate, tectonics, and relative sea level on a continentwide scale. In addition, coal quality is related to the regional depositional settings. Many aspects of coal quality (for example, maceral composition, ash content, sulfur content) are determined by the flora and hydrology of the mire in which the original peat accumulated. The existence of Cretaceous coals throughout the length of the Western Cordillera provides a unique opportunity to determine variations in mire type with climate over a range of 50/degrees/ of paleolatitude, and to examine the effects of these variations on coal quality. The relationships between coal beds and associated clastic facies should also be expected to change with varying mire types. Recent developments in their understanding of foreland basin evolution, Cretaceous sea level changes, and peat-forming environments make this an optimal time to begin a regional synthesis of North America's Cretaceous coals. Results of this study should aid the development of better predictive models of coal quality and seam thickness. These models will take into account the effects of major controls on sedimentation (climate, tectonics, sea level changes) rather than just the local depositional environment.

  9. A New Upper Jurassic Ophthalmosaurid Ichthyosaur from the Slottsmøya Member, Agardhfjellet Formation of Central Spitsbergen

    PubMed Central

    Roberts, Aubrey Jane; Druckenmiller, Patrick Scott; Sætre, Glenn-Peter; Hurum, Jørn Harald

    2014-01-01

    Abundant new ichthyosaur material has recently been documented in the Slottsmøya Member of the Agardhfjellet Formation from the Svalbard archipelago of Norway. Here we describe a partial skeleton of a new taxon, Janusaurus lundi, that includes much of the skull and representative portions of the postcranium. The new taxon is diagnosed by a suite of cranial character states including a very gracile stapedial shaft, the presence of a dorsal process on the prearticular and autapomorphic postcranial features such as the presence of an interclavicular trough and a conspicuous anterodorsal process of the ilium. The peculiar morphology of the ilia indicates a previously unrecognized degree of morphological variation in the pelvic girdle of ophthalmosaurids. We also present a large species level phylogenetic analysis of ophthalmosaurids including new and undescribed ichthyosaur material from the Upper Jurassic of Svalbard. Our results recover all Svalbard taxa in a single unresolved polytomy nested within Ophthalmosaurinae, which considerably increases the taxonomic composition of this clade. The paleobiogeographical implications of this result suggest the presence of a single clade of Boreal ophthalmosaurid ichthyosaurs that existed during the latest Jurassic, a pattern also reflected in the high degree of endemicity among some Boreal invertebrates, particularly ammonoids. Recent and ongoing descriptions of marine reptiles from the Slottsmøya Member Lagerstätte provide important new data to test hypotheses of marine amniote faunal turnover at the Jurassic-Cretaceous boundary. PMID:25084533

  10. Autocyclic progradation and allocyclic ravinement of a shoreface: Sedimentology and sequence stratigraphy of the Panther Sandstone Tongue (Upper Cretaceous, Campanian), Wasatch plateau, Utah, U. S. A

    SciTech Connect

    Krause, F.F.; Aitken, S.A.; Braunberger, W.F.; Chung, P.; Macrae, A.; Meyer, R.O.; Nunez-Betelu, L.; Williams, C.A.; Hol, H.M. )

    1993-04-01

    The Panther Sandstone Tongue of the Star Point Formation exposed in the vicinity of Helper, Utah reflects a coarse-grained, clastic wedge that penetrated the Mancos Shale basin in Early Campanian (Late Cretaceous) time. Panther Sandstone rocks may be grouped into six lithofacies: (1) thin-bedded, bioturbated and rippled, mudstone and very fine-grained sandstone; (2) thin- to medium-bedded, bioturbated, rippled and parallel laminated, mudstone and very fine-grained sandstone; (3) thick- to very thick-bedded HCS and parallel-laminated, mudstone and fine- to medium-grained sandstone; (4) medium- to thick-bedded, Ophiomorpha bioturbated, medium- to coarse-grained sandstone; (5) medium- to very-thick bedded, current bedded and hydroplasticly deformed sandstone, and (6) medium- to thick-bedded, trough cross-stratified and bundle-laminated, fine grained sandstone. Lithofacies are arranged in definable vertical and lateral successions. L. 1, 2 and 3 are upward coarsening and shoaling and are common in the Helper area. L. 5 and 6 are common to the west. L. 4 is a transgressive and ravinement lag that rests on all other lithofacies. Interpreted environments reflect a storm modified, microtidal, strandplain system. Rocks, except L. 4, are contained in a parasequence system that built into the basin during relative sea-level fall. This system prograded episodically suggesting varying sediment supply and event-controlled sediment reworking -- responses associated with autocyclic forcing. In contrast, ravinement decapitated the parasequence intersecting progressively shallower lithofacies. These responses suggest that ravinement was driven by allocyclic forcing, perhaps in response to tectonism in the foreland.

  11. WATER FORMATION IN THE UPPER ATMOSPHERE OF THE EARLY EARTH

    SciTech Connect

    Fleury, Benjamin; Carrasco, Nathalie; Marcq, Emmanuel; Vettier, Ludovic; Määttänen, Anni

    2015-07-10

    The water concentration and distribution in the early Earth's atmosphere are important parameters that contribute to the chemistry and the radiative budget of the atmosphere. If the atmosphere above the troposphere is generally considered as dry, photochemistry is known to be responsible for the production of numerous minor species. Here we used an experimental setup to study the production of water in conditions simulating the chemistry above the troposphere of the early Earth with an atmospheric composition based on three major molecules: N{sub 2}, CO{sub 2}, and H{sub 2}. The formation of gaseous products was monitored using infrared spectroscopy. Water was found as the major product, with approximately 10% of the gas products detected. This important water formation is discussed in the context of the early Earth.

  12. Cretaceous stratigraphy and biostratigraphy, Sierra Blanca basin, southeastern New Mexico

    SciTech Connect

    Lucas, S.G. ); Anderson, O.R. )

    1994-03-01

    The Sierra Blanca basin of Otero and Lincoln counties, New Mexico contains a Lower (upper Albian)-Upper (Santonian) Cretaceous section of marine and nonmarine strata as much as 700 m thick which represent the upper part of a regressive cycle followed by two transgressive-regressive deposition cycles. The lower 55 m of the Cretaceous section are the same tripartite Dakota Group units recognized in Guadalupe and San Miguel counties: basal Mesa Rica Sandstone (late Albian), medial Pajarito formation (late Albian) and upper Romeroville sandstone (earliest Cenomanian). The Mesa Rica and Pajarito represent a regression and are overlain disconformably by the transgressive Romeroville sandstone. Overlying transgressive marine clastics and minor carbonates of the Mancos Shale are as much as 73 m thick and include the early Turonian Greenhorn Limestone. The overlying Tres Hermanos formation (up to 91 m thick) consists of the (ascending order) Atarque sandstone and the Carthage and Fite Ranch sandstone members. These strata represent a mid-Turonian regression in response to regional tectonism (Atarque and Carthage), followed by a transgression (Fite Ranch sandstone) that ended in the deposition of the D-Cross Tongue of the Mancos Shale and Fort Hays Member of the Niobrara Formation during the late Turonian. The subsequent regression began with the Coniacian Gallup Sandstone (55 m) followed by coal-bearing Crevasse Canyon Formation (up to 244 m thick). The Coniacian-Santonian Crevasse Canyon Formation, the youngest Cretaceous unit in the basin, is disconformably overlain by middle Eocene conglomerates and red-bed siliciclastics of the Cub Mountain formation. Dakota Group age determinations in the Sierra Blanca basin are those of well-dated sections to the north, but ammonites and inoceramid bivalves from the Sierra Blanca basin provide precise age control for Cenomanian-Santonian marine and marginal marine strata and palynology and megafossil plants for nonmarine strata.

  13. A Ceratopsian Dinosaur from the Lower Cretaceous of Western North America, and the Biogeography of Neoceratopsia

    PubMed Central

    Farke, Andrew A.; Maxwell, W. Desmond; Cifelli, Richard L.; Wedel, Mathew J.

    2014-01-01

    The fossil record for neoceratopsian (horned) dinosaurs in the Lower Cretaceous of North America primarily comprises isolated teeth and postcrania of limited taxonomic resolution, hampering previous efforts to reconstruct the early evolution of this group in North America. An associated cranium and lower jaw from the Cloverly Formation (?middle–late Albian, between 104 and 109 million years old) of southern Montana is designated as the holotype for Aquilops americanus gen. et sp. nov. Aquilops americanus is distinguished by several autapomorphies, including a strongly hooked rostral bone with a midline boss and an elongate and sharply pointed antorbital fossa. The skull in the only known specimen is comparatively small, measuring 84 mm between the tips of the rostral and jugal. The taxon is interpreted as a basal neoceratopsian closely related to Early Cretaceous Asian taxa, such as Liaoceratops and Auroraceratops. Biogeographically, A. americanus probably originated via a dispersal from Asia into North America; the exact route of this dispersal is ambiguous, although a Beringian rather than European route seems more likely in light of the absence of ceratopsians in the Early Cretaceous of Europe. Other amniote clades show similar biogeographic patterns, supporting an intercontinental migratory event between Asia and North America during the late Early Cretaceous. The temporal and geographic distribution of Upper Cretaceous neoceratopsians (leptoceratopsids and ceratopsoids) suggests at least intermittent connections between North America and Asia through the early Late Cretaceous, likely followed by an interval of isolation and finally reconnection during the latest Cretaceous. PMID:25494182

  14. Upper mantle fluids involved in diamond formation and mantle metasomatism

    NASA Astrophysics Data System (ADS)

    Sverjensky, D. A.

    2014-12-01

    Diamond formation coupled with metasomatic reactions involving the interaction of fluids with silicate host rocks provides important clues about the deep carbon cycle. However, quantitative modeling of diamond formation with silicate rock metasomatism has not been possible. Here the Deep Water (DEW) model [1] was used to generate equilibrium constants for irreversible chemical mass transfer calculations monitoring evolving fluid chemistry during diamond formation and coupled silicate reactions. Conceptual models for diamond formation in two environments were constructed for the purpose of illustrating the role of pH in diamond-forming systems. For cratonic diamonds, fluid at 900°C and 5.0 GPa was derived in equilibrium with a carbonated mafic part of a subducting slab consisting of pure diopside, enstatite, pyrope, phlogopite, magnesite, diamond and pyrite. The fluid was assumed to infiltrate and react at constant T and P with a model metasedimentary eclogite (jadeite, pyrope, kyanite and coesite). Abundant diamond was predicted to precipitate as reactant silicate minerals were destroyed and secondary pyrope, jadeite and kyanite were precipitated, which could represent the solid inclusions in natural diamonds. The final fluid chemistry was extremely enriched in Si and depleted in Ca relative to the initial fluid, consistent with the worldwide fluid inclusion trend from carbonatitic fluid to silicic fluid. The logfO2 changed by only 0.2, whereas pH continuously decreased as reaction with jadeite and kyanite and precipitation of secondary pyrope removed Mg2+ and added H+ to the fluid. Most of the carbon precipitated as diamond was derived from decreasing concentrations of formate and propionate. In the UHPM scenario, fluid at 600°C and 5.0 GPa in carbonated peridotite (forsterite, antigorite, clinochlore, magnesite, and pyrrhotite) in a subducting slab was assumed to infiltrate and react at constant T and P with a different model metasedimentary eclogite (jadeite

  15. An overview of the Cretaceous stratigraphy and facies development of the Yazd Block, western Central Iran

    NASA Astrophysics Data System (ADS)

    Wilmsen, Markus; Fürsich, Franz Theodor; Majidifard, Mahmoud Reza

    2014-05-01

    The Cretaceous succession of the Yazd Block, the western of three structural blocks of the Central-East Iranian Microcontinent (CEIM), is in excess of 5,000 m thick. It has been studied in two key regions, i.e. the Khur and Yazd areas. Deposition started in both areas with terrestrial conglomerates and sandstones (Upper Jurassic?-lower Lower Cretaceous), covering Palaeozoic-Triassic basement rocks, weakly metamorphic rocks of the Upper Triassic-Liassic Shemshak Group or Jurassic granites. The basal unconformity is related to the Mid-/Late Cimmerian tectonic events (Bajocian and Jurassic-Cretaceous boundary interval) and shows a pronounced palaeo-relief. Thus, thicknesses of the basal terrestrial units (Chah Palang Formation and Noqreh formations in the Khur area, Sangestan Formation around Yazd) varies significantly from 0 to >1,500 m due to the levelling of the palaeo-relief. In the upper parts of the Noqreh and Sangestan Formations, interbedded terrestrial to marginal marine sediments indicate increasing marine influences during the Barremian. The following units, the Shah Kuh and Taft formations, comprise thick-bedded, micritic carbonates with abundant orbitolinid foraminifera, calcareous algae and rudists, attaining thicknesses of up to 1,000 m. They have a (late) Barremian-Aptian age and represent widespread shallow-marine carbonate platforms. Along an inter-regional drowning unconformity, the Shah Kuh and Taft carbonate platforms are overlain by up to 1.500-m-thick marly basinal sediments of late Aptian to Upper Albian age (Bazyab and Darreh-Zanjir formations). They characterize the maximum deepening in the Khur and Yazd areas during the Cretaceous period, related to significant subsidence rates. The following uppermost Albian-Middle Turonian Debarsu Formation (Khur area) is up to 600 m thick and consists of marls and bioclastic limestones, representing a carbonate ramp system prograding into the basinal system. It has a so far unnamed lithostratigraphical

  16. Paraclausastrea vorarlbergensis sp. nov.; a new coral from the Lower Cretaceous of western Austria (Scleractinia; upper Barremian-lower Aptian; Schrattenkalk Fm.; Vorarlberg).

    PubMed

    Baron-Szabo, Rosemarie C

    2015-10-16

    The new taxon Paraclausastrea vorarlbergensis sp. nov. is described from the upper Barremian-lower Aptian (Schrattenkalk Fm.) of western Austria (Vorarlberg). It belongs to the montlivaltiids and is characterized by thamnasterioid to submeandroid corallite integration, diameters of corallites ranging between 3 and 6.5 mm, and septa that are generally developed in 4 incomplete cycles in 6 generally irregular systems. In a small number corallites that are around 6 mm in diameter, 4 complete cycles are present. In corallites that are around 2 mm in diameter, usually between 12 and 18 septa are present. The new species differs from all other forms of Paraclausastrea in having the largest number of septa. This is the first report of this genus for the Schrattenkalk Formation.

  17. Early cretaceous radiolarian assemblages from the East Sakhalin Mountains

    NASA Astrophysics Data System (ADS)

    Kurilov, D. V.; Vishnevskaya, V. S.

    2011-02-01

    Three-dimensional radiolarian skeletons isolated from rock matrix in HF solution and then studied under scanning electron microscope substantiate the Early Cretaceous age of volcanogenic-cherty deposits sampled from fragmentary rock successions of the East Sakhalin Mountains. Accordingly the Berriasian age is established for jasper packets formerly attributed to the Upper Paleozoic-Mesozoic Daldagan Group; the Valanginian radiolarians are identified in cherty rock intercalations in the Upper Paleozoic (?) Ivashkino Formation; the Berriasian-Barremian assemblage is macerated from cherty tuffites of the Jurassic-Cretaceous Ostraya Formation; and the Aptian-early Albian radiolarians are characteristic of tuffaceous cherty rocks sampled from the Cretaceous Khoe Formation of the Nabil Group. Photographic documentation of radiolarian skeletons specifies taxonomic composition and age of the Berriasian, Valanginian, Berriasian-Valanginian, Barremian, and Aptian-Albian radiolarian assemblages from the East Sakhalin Mountains, and their evolution as related to abiotic events is considered. Coexistence of Tethyan and Pacific species in the same rock samples evidence origin of radiolarian assemblages in an ecotone. Consequently, the assemblages are applicable for intra- and interregional correlations and paleogeographic reconstructions.

  18. Stratigraphic relationships of Cretaceous and early Tertiary rocks of a part of northwestern San Juan basin

    USGS Publications Warehouse

    Baltz, Elmer Harold

    1953-01-01

    The Bridge Timber Mountain area in south-central La Plata County, southwestern Colorado lies mostly in the northwestern part of the Central San Juan Basin but contains a segment of the bounding Hogback 'monocline' and Four-Corners platform. The area contains rocks of late Cretaceous through early Eocene age, as well as Pliocene, Pleistocene, and Recent terrace and pediment gravels. The Pictured Cliffs sandstone of late Montana age is the latest marine formation present. Retreat of the Cretaceous seas from the area marked the beginning of Laramide orogenic activity and the earliest stages of deformation which produced the modern San Juan Basin. The Fruitland formation and Kirtland shale were deposited in brackish water and on coastal plains left by the retreating Cretaceous sea. Beds of the Farmington sandstone member and upper shale member of the Kirtland shale show evidence of a new source of sediments to the north or northeast distinct from the southwestern source area of older Cretaceous rocks. The McDermott 'formation', composed mainly of volcanic debris, is considered to be a local lower member of the Animas formation. Beds of the upper member of the Animas formation of Cretaceous and Paleocene age are considered to extend entirely across the area and into New Mexico. Overstep of higher sandstone and shale beds of the upper member across lower conglomeratic beds shows that folding on the Hogback 'monocline' began during deposition of the upper member. Beds of the upper member of the Animas formation grade laterally southward into Paleocene beds of the Nacimiento formation, but upper Nacimiento beds overstep folded beds of the Animas formation on the Hogback 'monocline' at the north end of Bridge Timber Mountain. The San Jose formation of Paleocene and Eocene age is conformable with the Nacimiento formation except at the north end of Bridge Timber Mountain where upper San Jose beds overstep all older tilted beds down to the Fruitland formation. The heavy

  19. Cretaceous tectonism, mineralization & hydrocarbon trap formation in the northern Canadian Cordillera: results of zircon (U-Th)/He thermochronology

    NASA Astrophysics Data System (ADS)

    Schneider, David; Powell, Jeremy; Ryan, Jim

    2013-04-01

    The northern Intermontane terranes of the Canadian Cordillera are dissected by a series of diachronous dextral strike-slip faults, including the Cretaceous Teslin fault possessing moderate displacement (~100 km) and the major Tertiary Tintina fault with >400 km displacement. The Teslin can be traced down to 7-8 seconds (~20 km) in seismic profiles and likely originated as a SW-directed thrust fault during the Jurassic which has been reactivated as a strike-slip fault in the Cretaceous. Jurassic cooling and exhumation of the middle crust now exposed across the central Yukon Cordillera has been slowly coming to light. We suggest unroofing is likely more widespread and long-lived then previously documented. Thirty Paleozoic and Mesozoic granitoids from the northern termination of the Teslin fault were selected for (U-Th)/He zircon thermochronology and only samples that exhibited typical igneous zoning and lack metamorphic overgrowths were analyzed. Analyses yield robust and reliable ages for each sample, which can be divided into three fault-parallel corridors: 215-130 Ma, 115-90 Ma, and 70-55 Ma. No clear pattern emerges when comparing age versus elevation, grain size, or mineral chemistry. The Klondike Plateau and rocks directly west of the Tintina fault record Jurassic cooling. The youngest domainal ages are proximal to voluminous Early to Mid-Cretaceous plutons and fault splays of the Teslin system, where structures with overall small displacement are associated with gold and copper-gold deposits. The remaining structural-age corridor can be resolved into a SW-directed extrusion wedge geometry, exhuming a large portion of the Yukon-Tanana terrane during Albian-Cenomanian tectonism. In the Cordilleran foreland front range of the Northwest Territories, 500 km to the northeast, detrital ZHe ages from ten Neoproterozoic units record contemporaneous cooling during the Late Cretaceous. Moreover, a subset of these samples serves to resolve the timing of movement on the

  20. Mollusks of the Upper Jurassic (upper Oxfordian-lower Kimmeridgian) shallow marine Minas Viejas Formation, northeastern Mexico

    NASA Astrophysics Data System (ADS)

    Zell, Patrick; Beckmann, Seija; Stinnesbeck, Wolfgang; Götte, Martin

    2015-10-01

    We present the first systematic description of Late Jurassic (late Oxfordian-early Kimmeridgian) invertebrates from the shallow marine Minas Viejas Formation of northeastern Mexico. The unit was generally considered to be extremely poor in fossils, due to an overall evaporitic character. The collection described here includes three taxa of ammonites, 10 taxa of bivalves and five taxa of gastropods. The fossils were discovered near Galeana and other localities in southern Nuevo León and northeastern San Luis Potosí, in thin-bedded marly limestones intercalated between gypsum units. Due to complex internal deformation of the sediments, fossils used for this study cannot be assigned to precise layers of origin. However, the taxa identified suggest a Late Jurassic (late Oxfordian-early Kimmeridgian) age for these fossil-bearing layers and allow us, for the first time, to assign a biostratigraphic age to Upper Jurassic strata in the region underlying the La Caja and La Casita formations.

  1. Absolute paleobathymetry of Upper Cretaceous chalks based on ostracodes - Evidence from the Demopolis Chalk (Campanian and Maastrichtian) of the northern Gulf Coastal Plain

    SciTech Connect

    Puckett, T.M. )

    1991-05-01

    The presence of abundant and diverse sighted ostracodes in chalk and marl of the Demopolis Chalk (Campanian and Maastrichtian) in Alabama and Mississippi strongly suggests that the Late Cretaceous sea floor was within the photic zone. The maximum depth of deposition is calculated from an equation based on eye morphology and efficiency and estimates of the vertical light attenuation. In this equation, K, the vertical light attenuation coefficient, is the most critical variable because it is the divisor for the rest of the equation. Rates of accumulation of coccoliths during the Cretaceous are estimated and are on the same order as those in modern areas of high phytoplankton production, suggesting similar pigment and coccolith concentrations in the water column. Values of K are known for a wide range of water masses and pigment concentrations, including areas of high phytoplankton production; thus light attenuation through the Cretaceous seas can be estimated reliably. Waters in which attenuation is due only to biogenic matter-conditions that result in deposition of relatively pure chalk-have values of K ranging between 0.2 and 0.3. Waters rich in phytoplankton and mud-conditions that result in deposition of marl-have K values as great as 0.5. Substituting these values for K results in depth range of 65 to 90 m for deposition of chalk and depth of 35 m for deposition of marl. These depth values suggest that deposition of many Cretaceous chalks and marls around the world were deposited under relatively shallow conditions.

  2. An Unusual Pterosaur Specimen (Pterodactyloidea, ?Azhdarchoidea) from the Early Cretaceous Romualdo Formation of Brazil, and the Evolution of the Pterodactyloid Palate

    PubMed Central

    Pinheiro, Felipe L.; Schultz, Cesar L.

    2012-01-01

    A new and unusual specimen of a probable azhdarchoid pterosaur is described for the Early Cretaceous (Albian) Romualdo Formation of Brazil. The specimen consists of a palate that, although fragmentary, has a unique morphology differing from all other known pterosaurs with preservation of palatal elements. The new specimen probably indicates the presence of a yet undescribed pterodactyloid taxon for Romualdo Formation and brings new information on pterosaur diversity of this sedimentary unity. Mainly due to the rarity of pterodactyloid specimens with palate preservation, this structure has been overlooked in this clade. Here, we reassess the palatal anatomy of Pterodactyloidea, revealing an intriguing variety of morphotypes and evolutionary trends, some of them described here for the first time. The morphological disparity displayed by different pterodactyloid taxa may be further evidence of the presence of diverse feeding strategies within the clade. PMID:23185539

  3. An unusual pterosaur specimen (Pterodactyloidea, ?azhdarchoidea) from the early cretaceous Romualdo formation of Brazil, and the evolution of the pterodactyloid palate.

    PubMed

    Pinheiro, Felipe L; Schultz, Cesar L

    2012-01-01

    A new and unusual specimen of a probable azhdarchoid pterosaur is described for the Early Cretaceous (Albian) Romualdo Formation of Brazil. The specimen consists of a palate that, although fragmentary, has a unique morphology differing from all other known pterosaurs with preservation of palatal elements. The new specimen probably indicates the presence of a yet undescribed pterodactyloid taxon for Romualdo Formation and brings new information on pterosaur diversity of this sedimentary unity. Mainly due to the rarity of pterodactyloid specimens with palate preservation, this structure has been overlooked in this clade. Here, we reassess the palatal anatomy of Pterodactyloidea, revealing an intriguing variety of morphotypes and evolutionary trends, some of them described here for the first time. The morphological disparity displayed by different pterodactyloid taxa may be further evidence of the presence of diverse feeding strategies within the clade.

  4. High resolution sup 40 Ar/ sup 39 Ar chronostratigraphy of the Late Cretaceous El Gallo Formation, Baja California del Norte, Mexico

    SciTech Connect

    Fulford, M.M.; Busby-Spera, C. ); Renne, P.R.

    1991-03-01

    Laser probe {sup 40}Ar/{sup 39}Ar analyses of individual sanidine grains from four tuffs in the alluvial Late Cretaceous (Campanian) El Gallo Formation yield statistically distinct mean dates ranging from 74.87 {plus minus} 0.05 Ma to 73.59 {plus minus} 0.09 Ma. The exceptional precision of these dates permits calculation of statistically significant sediment accumulation rates that are much higher than passive sediment loading would cause, implying rapid tectonically induced subsidence. The dates bracket tightly the age of important dinosaur and mammalian faunas previously reported from the El Gallo Formation. The dates support an age less than 73 Ma for the Campanian/Maastrichtian stage boundary, younger than indicated by several currently used time scales. Further application of the single grain {sup 40}Ar/{sup 39}Ar technique may be expected to greatly benefit stratigraphic studies of Mesozoic sedimentary basins and contribute to calibration of biostratigraphic and magnetostratigraphic time scales.

  5. Stratigraphic framework of the upper Fort Union Formation, TA Hills, Western Powder River basin, Wyoming

    USGS Publications Warehouse

    Weaver, Jean N.; Flores, Romeo M.

    1985-01-01

    The purpose of this study is to interpret a relationship between the stratigraphy and the environment of deposition of the upper part of the Fort Union Formation in the TA Hills in the western part of the Powder River Basin, Johnson County, Wyoming.  This framework was used to map and correlate coal beds with those mapped by Hose (1955) and Mapel (1959) in the southern and northern parts of the study area, respectively.  More specifically, the established stratigraphic and environmental relationships of the coal beds and associated rocks contribute to a depositional model for the upper part of the Fort Union Formation in the TA Hills.

  6. An Ornithopod-Dominated Tracksite from the Lower Cretaceous Jiaguan Formation (Barremian–Albian) of Qijiang, South-Central China: New Discoveries, Ichnotaxonomy, Preservation and Palaeoecology

    PubMed Central

    Xing, Lida; Lockley, Martin G.; Marty, Daniel; Zhang, Jianping; Wang, Yan; Klein, Hendrik; McCrea, Richard T.; Buckley, Lisa G.; Belvedere, Matteo; Mateus, Octávio; Gierliński, Gerard D.; Piñuela, Laura; Persons, W. Scott; Wang, Fengping; Ran, Hao; Dai, Hui; Xie, Xianming

    2015-01-01

    The historically-famous Lotus Fortress site, a deep 1.5–3.0-meter-high, 200-meter-long horizonal notch high up in near-vertical sandstone cliffs comprising the Cretaceous Jiaguan Formation, has been known since the 13th Century as an impregnable defensive position. The site is also extraordinary for having multiple tetrapod track-bearing levels, of which the lower two form the floor of part of the notch, and yield very well preserved asseamblages of ornithopod, bird (avian theropod) and pterosaur tracks. Trackway counts indicate that ornithopods dominate (69%) accounting for at least 165 trackmakers, followed by bird (18%), sauropod (10%), and pterosaur (3%). Previous studies designated Lotus Fortress as the type locality of Caririchnium lotus and Wupus agilis both of which are recognized here as valid ichnotaxa. On the basis of multiple parallel trackways both are interpreted as representing the trackways of gregarious species. C. lotus is redescribed here in detail and interpreted to indicate two age cohorts representing subadults that were sometimes bipedal and larger quadrupedal adults. Two other previously described dinosaurian ichnospecies, are here reinterpreted as underprints and considered nomina dubia. Like a growing number of significant tetrapod tracksites in China the Lotus Fortress site reveals new information about the composition of tetrapod faunas from formations in which the skeletal record is sparse. In particular, the site shows the relatively high abundance of Caririchium in a region where saurischian ichnofaunas are often dominant. It is also the only site known to have yielded Wupus agilis. In combination with information from other tracksites from the Jiaguan formation and other Cretaceous formations in the region, the track record is proving increasingly impotant as a major source of information on the vertebrate faunas of the region. The Lotus Fortress site has been developed as a spectacular, geologically-, paleontologically- and a

  7. An Ornithopod-Dominated Tracksite from the Lower Cretaceous Jiaguan Formation (Barremian-Albian) of Qijiang, South-Central China: New Discoveries, Ichnotaxonomy, Preservation and Palaeoecology.

    PubMed

    Xing, Lida; Lockley, Martin G; Marty, Daniel; Zhang, Jianping; Wang, Yan; Klein, Hendrik; McCrea, Richard T; Buckley, Lisa G; Belvedere, Matteo; Mateus, Octávio; Gierliński, Gerard D; Piñuela, Laura; Persons, W Scott; Wang, Fengping; Ran, Hao; Dai, Hui; Xie, Xianming

    2015-01-01

    The historically-famous Lotus Fortress site, a deep 1.5-3.0-meter-high, 200-meter-long horizonal notch high up in near-vertical sandstone cliffs comprising the Cretaceous Jiaguan Formation, has been known since the 13th Century as an impregnable defensive position. The site is also extraordinary for having multiple tetrapod track-bearing levels, of which the lower two form the floor of part of the notch, and yield very well preserved asseamblages of ornithopod, bird (avian theropod) and pterosaur tracks. Trackway counts indicate that ornithopods dominate (69%) accounting for at least 165 trackmakers, followed by bird (18%), sauropod (10%), and pterosaur (3%). Previous studies designated Lotus Fortress as the type locality of Caririchnium lotus and Wupus agilis both of which are recognized here as valid ichnotaxa. On the basis of multiple parallel trackways both are interpreted as representing the trackways of gregarious species. C. lotus is redescribed here in detail and interpreted to indicate two age cohorts representing subadults that were sometimes bipedal and larger quadrupedal adults. Two other previously described dinosaurian ichnospecies, are here reinterpreted as underprints and considered nomina dubia. Like a growing number of significant tetrapod tracksites in China the Lotus Fortress site reveals new information about the composition of tetrapod faunas from formations in which the skeletal record is sparse. In particular, the site shows the relatively high abundance of Caririchium in a region where saurischian ichnofaunas are often dominant. It is also the only site known to have yielded Wupus agilis. In combination with information from other tracksites from the Jiaguan formation and other Cretaceous formations in the region, the track record is proving increasingly impotant as a major source of information on the vertebrate faunas of the region. The Lotus Fortress site has been developed as a spectacular, geologically-, paleontologically- and a

  8. An Ornithopod-Dominated Tracksite from the Lower Cretaceous Jiaguan Formation (Barremian-Albian) of Qijiang, South-Central China: New Discoveries, Ichnotaxonomy, Preservation and Palaeoecology.

    PubMed

    Xing, Lida; Lockley, Martin G; Marty, Daniel; Zhang, Jianping; Wang, Yan; Klein, Hendrik; McCrea, Richard T; Buckley, Lisa G; Belvedere, Matteo; Mateus, Octávio; Gierliński, Gerard D; Piñuela, Laura; Persons, W Scott; Wang, Fengping; Ran, Hao; Dai, Hui; Xie, Xianming

    2015-01-01

    The historically-famous Lotus Fortress site, a deep 1.5-3.0-meter-high, 200-meter-long horizonal notch high up in near-vertical sandstone cliffs comprising the Cretaceous Jiaguan Formation, has been known since the 13th Century as an impregnable defensive position. The site is also extraordinary for having multiple tetrapod track-bearing levels, of which the lower two form the floor of part of the notch, and yield very well preserved asseamblages of ornithopod, bird (avian theropod) and pterosaur tracks. Trackway counts indicate that ornithopods dominate (69%) accounting for at least 165 trackmakers, followed by bird (18%), sauropod (10%), and pterosaur (3%). Previous studies designated Lotus Fortress as the type locality of Caririchnium lotus and Wupus agilis both of which are recognized here as valid ichnotaxa. On the basis of multiple parallel trackways both are interpreted as representing the trackways of gregarious species. C. lotus is redescribed here in detail and interpreted to indicate two age cohorts representing subadults that were sometimes bipedal and larger quadrupedal adults. Two other previously described dinosaurian ichnospecies, are here reinterpreted as underprints and considered nomina dubia. Like a growing number of significant tetrapod tracksites in China the Lotus Fortress site reveals new information about the composition of tetrapod faunas from formations in which the skeletal record is sparse. In particular, the site shows the relatively high abundance of Caririchium in a region where saurischian ichnofaunas are often dominant. It is also the only site known to have yielded Wupus agilis. In combination with information from other tracksites from the Jiaguan formation and other Cretaceous formations in the region, the track record is proving increasingly impotant as a major source of information on the vertebrate faunas of the region. The Lotus Fortress site has been developed as a spectacular, geologically-, paleontologically- and a

  9. Did tropical rainforest vegetation exist during the Late Cretaceous? New data from the late Campanian to early Maastrichtian Olmos Formation, Coahuila, Mexico.

    NASA Astrophysics Data System (ADS)

    Upchurch, G. R.; Estrada-Ruiz, E.; Cevallos-Ferriz, S. S.

    2008-12-01

    A major problem in paleobotany and paleoclimatology is the origin of modern tropical and paratropical rainforests. Studies of leaf macrofossils, beginning with those of Wolfe and Upchurch, have suggested that tropical and paratropical (i.e., megathermal) rainforests with dominant angiosperms are of Cenozoic origin, and that comparable vegetation was either absent or greatly restricted during the Late Cretaceous. Earth System modeling studies, in contrast, predict the existence of megathermal rainforest vegetation during the mid- and Late Cretaceous, though with less areal extent than during the Late Cenozoic and Recent. Megathermal climate with year-round precipitation is simulated along the paleoequator and along the northern margin of the Tethys Ocean, and tends to occur in highly focused regions, in contrast to the more latitudinally zoned pattern of the Recent. Low-resolution climatic indicators, such as the distribution of coals and tree fern spores, are consistent with evidence from climate modeling for megathermal wet climates during the Late Cretaceous, and by extension megathermal rainforest vegetation. However, corroborative data from plant macrofossil assemblages is needed, because the physiognomy of leaves and woods directly reflects plant adaptation to the environment and can estimate climate independently of the generic and familial affinities of the paleoflora. Newly collected plant macrofossil assemblages from the late Campian to early Maastrichtian Olmos Formation of Coahuila, Mexico, provide evidence for megathermal rainforest vegetation on the northern margin of the Tethys Ocean at approximately 35 degrees paleolatitude. The newly collected leaf flora is 72 percent entire- margined and has abundant palms, features typical of modern megathermal rainforests. Thirty percent of the species have large leaves, and 50 percent of the species have drip tips, features indicative of wet conditions. Simple and multiple regression functions based on the

  10. Continental fossil vertebrates from the mid-Cretaceous (Albian-Cenomanian) Alcântara Formation, Brazil, and their relationship with contemporaneous faunas from North Africa

    NASA Astrophysics Data System (ADS)

    Candeiro, Carlos Roberto A.; Fanti, Federico; Therrien, François; Lamanna, Matthew C.

    2011-05-01

    The Albian-Cenomanian Alcântara Formation of northeastern Brazil preserves the most diverse continental vertebrate fauna of this age yet known from northern South America. The Alcântara vertebrate assemblage, consisting of elasmobranchs, actinopterygians, sarcopterygians, turtles, crocodyliforms, pterosaurs, and non-avian dinosaurs, displays close similarities to contemporaneous faunas from North Africa. The co-occurrence of as many as eight freshwater or estuarine fish taxa ( Onchopristis, Bartschichthys, Lepidotes, Stephanodus, Mawsonia, Arganodus, Ceratodus africanus, and possibly Ceratodus humei) and up to seven terrestrial archosaur taxa ( Sigilmassasaurus, Rebbachisauridae, Baryonychinae, Spinosaurinae, Carcharodontosauridae, possibly Pholidosauridae, and doubtfully Bahariasaurus) suggests that a land route connecting northeastern Brazil and North Africa existed at least until the Albian. Interestingly, most components of this mid-Cretaceous northern South American/North African assemblage are not shared with coeval southern South American faunas, which are themselves characterized by a number of distinct freshwater and terrestrial vertebrate taxa (e.g., chelid turtles, megaraptoran and unenlagiine theropods). These results suggest that, although mid-Cretaceous faunal interchange was probably possible between northern South America and North Africa, paleogeographic, paleoclimatic, and/or paleoenvironmental barriers may have hindered continental vertebrate dispersal between northern and southern South America during this time.

  11. Evaluation of organic matter, subsurface temperature and pressure with regard to gas generation in low-permeability Upper Cretaceous and Lower Tertiary sandstones in Pacific Creek area, Sublette and Sweetwater Counties, Wyoming.

    USGS Publications Warehouse

    Law, B.E.; Spencer, C.W.; Bostick, N.H.

    1980-01-01

    The onset of overpressuring occurs at c.3,500 m, near the base of the U. Cretaceous Lance Formation. The development of overpressuring may involve several processes; however, interpretation of the available information indicates that active generation of large amounts of wet gas is one of the more important processes. The present minimum temperature at the top of overpressuring is at least 88oC. The preservation of abnormally high pressures is due to presently active generation of gas in a thick interval of discontinuous, very low-permeability shales, siltstones, and sandstones. - from Authors

  12. K/Ar chronologies of tephra units from the Middle Jurassic Sundance, and Late Early Cretaceous Mowry and Shell Creek Formations, Big Horn Basin, WY

    NASA Astrophysics Data System (ADS)

    Jiang, H.; Meyer, E. E.; Johnson, G. D.

    2013-12-01

    The Middle Jurassic Sundance and Late Early Cretaceous Shell Creek and Mowry Formations of the Big Horn Basin, Wyoming, contain an extensive record of altered tephra. These tephra are likely related to contemporary volcanic activity in the Sierra Nevada and various Coast Range terranes to the west and provide valuable chronometric control on the sedimentary record within a portion of the Sevier-aged and later Cordilleran foreland basin. In addition, several of these altered tephra (bentonites) provide a valuable economic resource. Despite the prominence of these strata across the basin, few isotopic ages have been reported to date. Here we present new K/Ar ages on biotite phenocrysts from those tephra occurrences as a chronometric check on samples that contained zircons with significant Pb loss, that preclude more precise U/Pb age determinations. A bulk biotite sample extracted from an altered tuff in the Lower Sundance Formation gives an age of 167.5 × 5 Ma. This tuff occurs just above a dinosaur track-bearing peritidal sequence. Bulk biotite ages from the lower Shell Creek Formation give an age of 100.3 × 3 Ma and are statistically indistinguishable from biotite grains dated at 103.1 × 3 Ma extracted from the economically important 'Clay Spur' bentonite found at the top of the Mowry Shale. This work provides important new chronometric constraints on a portion of the Medial Jurassic to Late Early Cretaceous stratigraphy of the Big Horn Basin, Wyoming, and may be useful in understanding the regional tectonics that helped shape the development of the Sevier foreland basin and Western Interior Seaway.

  13. Sedimentology and sequence stratigraphy from outcrops of the Kribi-Campo sub-basin: Lower Mundeck Formation (Lower Cretaceous, southern Cameroon)

    NASA Astrophysics Data System (ADS)

    Ntamak-Nida, Marie Joseph; Bourquin, Sylvie; Makong, Jean-Claude; Baudin, François; Mpesse, Jean Engelbert; Ngouem, Christophe Itjoko; Komguem, Paul Bertrand; Abolo, Guy Martin

    2010-08-01

    The Kribi-Campo sub-basin is composed of an Early to Mid Cretaceous series from West Africa's Atlantic coast and is located in southern Cameroon in the Central African equatorial rain forest. It is the smallest coastal basin in Cameroon and forms the southern part of the Douala/Kribi-Campo basin known as Douala basin ( s.l.). Until now, no detailed sedimentological studies have been carried out on the outcrops of this basin located in the Campo area. The aim of this study was to characterise the depositional environments, vertical evolution and tectonic context of these Lower Cretaceous series in order to make a comparison with adjacent basins and replace them in the geodynamic context. Facies analysis of the Lower Mundeck Formation (Lower Cretaceous) indicates the presence of four major, interfigered facies associations, that are inferred to represent elements of an alluvial to lacustrine-fan delta system. The clast lithologies suggest proximity of relief supplying coarse-grained sediment during the deposition of the Lower Mundeck Formation at Campo. The general dip and direction of the bedding is approximately 10°-12°NW, which also corresponds to the orientation of the foliations in the underlying metamorphic basement. The main sedimentary succession is characterised by a major retrogradational/progradational cycle of Late Aptian age, evaluated at about 3 Ma, with a well-developed progradational trend characterised by fluctuations of the recognised depositional environments. Fluctuations in lake level and sediment supply were possibly controlled by active faults at the basin margin, although climatic changes may have also played a role. The consistently W-WNW palaeoflow of sediments suggests that the palaeorelief was located to the east and could be oriented in a NNE-SSW direction, downthrown to the west. Local outcrops dated as Albian, both north and south of the main outcrop, display some marine influence. These deposits are cut by 040-060 faults parallel to

  14. Formative Assessment and Increased Student Involvement Increase Grades in an Upper Secondary School Biology Course

    ERIC Educational Resources Information Center

    Granbom, Martin

    2016-01-01

    This study shows that formative methods and increased student participation has a positive influence on learning measured as grades. The study was conducted during the course Biology A in a Swedish Upper Secondary School. The students constructed grade criteria and defined working methods and type of examination within a given topic, Gene…

  15. Evidence for high taxonomic and morphologic tyrannosauroid diversity in the Late Cretaceous (Late Campanian) of the American Southwest and a new short-skulled tyrannosaurid from the Kaiparowits formation of Utah

    NASA Astrophysics Data System (ADS)

    Carr, Thomas D.; Williamson, Thomas E.; Britt, Brooks B.; Stadtman, Ken

    2011-03-01

    The fossil record of late Campanian tyrannosauroids of western North America has a geographic gap between the Northern Rocky Mountain Region (Montana, Alberta) and the Southwest (New Mexico, Utah). Until recently, diagnostic tyrannosauroids from the Southwest were unknown until the discovery of Bistahieversor sealeyi from the late Campanian of New Mexico. Here we describe an incomplete skull and postcranial skeleton of an unusual tyrannosaurid from the Kaiparowits Formation (Late Cretaceous) of Utah that represents a new genus and species, Teratophoneus curriei. Teratophoneus differs from other tyrannosauroids in having a short skull, as indicated by a short and steep maxilla, abrupt angle in the postorbital process of the jugal, laterally oriented paroccipital processes, short basicranium, and reduced number of teeth. Teratophoneus is the sister taxon of the Daspletosaurus + Tyrannosaurus clade and it is the most basal North American tyrannosaurine. The presence of Teratophoneus suggests that dinosaur faunas were regionally endemic in the west during the upper Campanian. The divergence in skull form seen in tyrannosaurines indicates that the skull in this clade had a wide range of adaptive morphotypes.

  16. Evidence for high taxonomic and morphologic tyrannosauroid diversity in the Late Cretaceous (late Campanian) of the American Southwest and a new short-skulled tyrannosaurid from the Kaiparowits Formation of Utah.

    PubMed

    Carr, Thomas D; Williamson, Thomas E; Britt, Brooks B; Stadtman, Ken

    2011-03-01

    The fossil record of late Campanian tyrannosauroids of western North America has a geographic gap between the Northern Rocky Mountain Region (Montana, Alberta) and the Southwest (New Mexico, Utah). Until recently, diagnostic tyrannosauroids from the Southwest were unknown until the discovery of Bistahieversor sealeyi from the late Campanian of New Mexico. Here we describe an incomplete skull and postcranial skeleton of an unusual tyrannosaurid from the Kaiparowits Formation (Late Cretaceous) of Utah that represents a new genus and species, Teratophoneus curriei. Teratophoneus differs from other tyrannosauroids in having a short skull, as indicated by a short and steep maxilla, abrupt angle in the postorbital process of the jugal, laterally oriented paroccipital processes, short basicranium, and reduced number of teeth. Teratophoneus is the sister taxon of the Daspletosaurus + Tyrannosaurus clade and it is the most basal North American tyrannosaurine. The presence of Teratophoneus suggests that dinosaur faunas were regionally endemic in the west during the upper Campanian. The divergence in skull form seen in tyrannosaurines indicates that the skull in this clade had a wide range of adaptive morphotypes.

  17. The functional and palaeoecological implications of tooth morphology and wear for the megaherbivorous dinosaurs from the Dinosaur Park Formation (upper Campanian) of Alberta, Canada.

    PubMed

    Mallon, Jordan C; Anderson, Jason S

    2014-01-01

    Megaherbivorous dinosaurs were exceptionally diverse on the Late Cretaceous island continent of Laramidia, and a growing body of evidence suggests that this diversity was facilitated by dietary niche partitioning. We test this hypothesis using the fossil megaherbivore assemblage from the Dinosaur Park Formation (upper Campanian) of Alberta as a model. Comparative tooth morphology and wear, including the first use of quantitative dental microwear analysis in the context of Cretaceous palaeosynecology, are used to infer the mechanical properties of the foods these dinosaurs consumed. The phylliform teeth of ankylosaurs were poorly adapted for habitually processing high-fibre plant matter. Nevertheless, ankylosaur diets were likely more varied than traditionally assumed: the relatively large, bladed teeth of nodosaurids would have been better adapted to processing a tougher, more fibrous diet than the smaller, cusp-like teeth of ankylosaurids. Ankylosaur microwear is characterized by a preponderance of pits and scratches, akin to modern mixed feeders, but offers no support for interspecific dietary differences. The shearing tooth batteries of ceratopsids are much better adapted to high-fibre herbivory, attested by their scratch-dominated microwear signature. There is tentative microwear evidence to suggest differences in the feeding habits of centrosaurines and chasmosaurines, but statistical support is not significant. The tooth batteries of hadrosaurids were capable of both shearing and crushing functions, suggestive of a broad dietary range. Their microwear signal overlaps broadly with that of ankylosaurs, and suggests possible dietary differences between hadrosaurines and lambeosaurines. Tooth wear evidence further indicates that all forms considered here exhibited some degree of masticatory propaliny. Our findings reveal that tooth morphology and wear exhibit different, but complimentary, dietary signals that combine to support the hypothesis of dietary niche

  18. The Functional and Palaeoecological Implications of Tooth Morphology and Wear for the Megaherbivorous Dinosaurs from the Dinosaur Park Formation (Upper Campanian) of Alberta, Canada

    PubMed Central

    Mallon, Jordan C.; Anderson, Jason S.

    2014-01-01

    Megaherbivorous dinosaurs were exceptionally diverse on the Late Cretaceous island continent of Laramidia, and a growing body of evidence suggests that this diversity was facilitated by dietary niche partitioning. We test this hypothesis using the fossil megaherbivore assemblage from the Dinosaur Park Formation (upper Campanian) of Alberta as a model. Comparative tooth morphology and wear, including the first use of quantitative dental microwear analysis in the context of Cretaceous palaeosynecology, are used to infer the mechanical properties of the foods these dinosaurs consumed. The phylliform teeth of ankylosaurs were poorly adapted for habitually processing high-fibre plant matter. Nevertheless, ankylosaur diets were likely more varied than traditionally assumed: the relatively large, bladed teeth of nodosaurids would have been better adapted to processing a tougher, more fibrous diet than the smaller, cusp-like teeth of ankylosaurids. Ankylosaur microwear is characterized by a preponderance of pits and scratches, akin to modern mixed feeders, but offers no support for interspecific dietary differences. The shearing tooth batteries of ceratopsids are much better adapted to high-fibre herbivory, attested by their scratch-dominated microwear signature. There is tentative microwear evidence to suggest differences in the feeding habits of centrosaurines and chasmosaurines, but statistical support is not significant. The tooth batteries of hadrosaurids were capable of both shearing and crushing functions, suggestive of a broad dietary range. Their microwear signal overlaps broadly with that of ankylosaurs, and suggests possible dietary differences between hadrosaurines and lambeosaurines. Tooth wear evidence further indicates that all forms considered here exhibited some degree of masticatory propaliny. Our findings reveal that tooth morphology and wear exhibit different, but complimentary, dietary signals that combine to support the hypothesis of dietary niche

  19. The evolution of deltaic depositional systems in a sequence stratigraphic framework; Upper Cretaceous Dunvegan Formation, Alberta subsurface

    SciTech Connect

    Bhattacharya, J. )

    1991-03-01

    Sequence stratigraphic subdivision of the Dunvegan clastic wedge allows the recognition and delineation of discrete shoreline related depositional systems over an area of 30,000 km{sup 2}, using 500 well logs and 130 cores. These depositional systems are recognized at the parasequence scale and can be grouped (from oldest to younges