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Sample records for formation upper cretaceous

  1. 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.

  2. 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.

  3. Playa lake and sheetflood deposits of the Upper Cretaceous Jindong Formation, Korea: Occurrences and palaeoenvironments

    NASA Astrophysics Data System (ADS)

    Paik, I. S.; Kim, H. J.

    2006-05-01

    Lake model of the Upper Cretaceous Jindong Formation in Korea was established on the basis of sedimentological and palaeobiological records of the playa lake and sheetflood deposits and their palaeoenvironmental implications. The playa lake and sheetflood deposits of the Jindong Formation are characterized by the common presence of traces of vanished evaporites, complicated polygonal desiccation cracks and rainprints, the pedogenic carbonate development, and the preservation of invertebrate traces and dinosaur and bird tracks. The traces of vanished evaporites including halite and sulphate evaporite occur as evaporite pseudopmorphs and moulds. The occurrence of all of the evaporite minerals as traces suggests that flooding stages persisted much longer than evaporation and desiccation stages. Invertebrates, birds, and dinosaurs inhabited the playa lake environment of the Upper Cretaceous Jindong Lake. The Jindong Lake formed by the combination of humid source area and arid depositional site due to an orographic effect in fault-bounded basin. Extensive development of the playa lake and sheetflood deposits with evaporite mineral casts and very limited association of shoreline deposits in the Jindong Formation are characteristic of closed lake, and the Jindong Lake is compared to a lake formed in partly drained closed basin. The aggradation of mudflat deposits indicates continued subsidence of the basin and continuation of an underfilled lake basin. The Jindong Lake expanded and stabilized as a playa lake surrounded by dry to saline mudflats, and palaeoclimate and subsidence rates changed little throughout the period of the Jindong Lake development.

  4. 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.

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

    NASA Astrophysics Data System (ADS)

    Lofgren, Donald L.; Hotton, Carol L.; Runkel, Anthony 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 they (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.

  6. 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.

  7. Authigenic dolomite cementation in the Upper Cretaceous Phosphate Formation, Western Desert, Egypt

    NASA Astrophysics Data System (ADS)

    Rifai, Rifai I.; Shaaban, Mohamad N.

    2007-12-01

    The Upper Cretaceous Phosphate Formation in the Western Desert of Egypt displays a characteristic facies association that includes marine phosphorites interbedded with black shales and glauconitic sandstones. The upper part of the formation is characterized by the presence of thin phosphatic beds, which are filled-extensively-with disordered and non stoichiometric (mean MgCO 3 = 41.4 ± 0.34 mol%) authigenic dolomite cement. SEM and the back scattered images of these coarse crystalline dolomite cements reveal that they display planar euhedral crystal boundaries, polymodal crystal size distribution and variable inclusion pattern. The relatively low and wide ranged δ18O (- 0.87 to - 4.15‰ VPDB) values of the dolomite cements coupled with their depleted Sr (mean = 187 ± 26 ppm) and high iron and manganese values (mean = 6851 ± 554 ppm and 11599 ± 229 ppm respectively) invoke that they were formed from mixed hypo-saline fluids within a mixing marine-meteoric zone probably during a low stand period at the vicinity of the Maastrichtian/Early Tertiary unconformity. Meanwhile, their negative δ13C (- 1.31 to - 3.56‰ VPDB) values argue for a possible involvement of isotopically light carbon, derived from degradation of organic matter, during their precipitation.

  8. Crocodyliform Feeding Traces on Juvenile Ornithischian Dinosaurs from the Upper Cretaceous (Campanian) Kaiparowits Formation, Utah

    PubMed Central

    Boyd, Clint A.; Drumheller, Stephanie K.; Gates, Terry A.

    2013-01-01

    Crocodyliforms serve as important taphonomic agents, accumulating and modifying vertebrate remains. Previous discussions of Mesozoic crocodyliform feeding in terrestrial and riverine ecosystems have often focused on larger taxa and their interactions with equally large dinosaurian prey. However, recent evidence suggests that the impact of smaller crocodyliforms on their environments should not be discounted. Here we present direct evidence of feeding by a small crocodyliform on juvenile specimens of a ‘hypsilophodontid’ dinosaur from the Upper Cretaceous (Campanian) Kaiparowits Formation of southern Utah. Diagnostic crocodyliform bite marks present on a left scapula and a right femur, as well as a partial probable crocodyliform tooth crown (ovoid in cross-section) preserved within a puncture on the right femur, comprise the bulk of the feeding evidence. Computed tomography scans of the femoral puncture reveal impact damage to the surrounding bone and that the distal tip of the embedded tooth was missing prior to the biting event. This is only the second reported incidence of a fossil crocodyliform tooth being found embedded directly into prey bone. These bite marks provide insight into the trophic interactions of the ecosystem preserved in the Kaiparowits Formation. The high diversity of crocodyliforms within this formation may have led to accentuated niche partitioning, which seems to have included juvenile dinosaurian prey. PMID:23460882

  9. 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

  10. 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

  11. 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.

  12. Dinosaurs remains from western São Paulo state, Brazil (Bauru Basin, Adamantina Formation, Upper Cretaceous)

    NASA Astrophysics Data System (ADS)

    Candeiro, C. R. A.; Abranches, C. T.; Abrantes, E. A.; Avilla, L. S.; Martins, V. C.; Moreira, A. L.; Torres, S. R.; Bergqvist, L. P.

    2004-12-01

    In this contribution is presented the preliminary results of a paleontological expedition to five Upper Cretaceous fossil sites in the western part of the state of São Paulo, Brazil. Although the material is fragmented, the recovered fossils constitute an important record of the theropod dinosaur; some isolated teeth are the first record of Carcharodontosauridae in the Upper Cretaceous period in Brazil. The authors group the teeth of the theropod into five morphological groups on the basis of the general morphology of each tooth's cross-section and the presence of wrinkles on the crown. Spinosaurid and abelisaurid are also represented in this assembly, though other morph groups remain undetermined. One tooth in particular and a caudal vertebra indicate the presence of sauropods from the family Titanosauridae family.

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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

  1. 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.

  2. 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

  3. Dinosaur Census Reveals Abundant Tyrannosaurus and Rare Ontogenetic Stages in the Upper Cretaceous Hell Creek Formation (Maastrichtian), Montana, USA

    PubMed Central

    Horner, John R.; Goodwin, Mark B.; Myhrvold, Nathan

    2011-01-01

    Background A dinosaur census recorded during the Hell Creek Project (1999–2009) incorporates multiple lines of evidence from geography, taphohistory, stratigraphy, phylogeny and ontogeny to investigate the relative abundance of large dinosaurs preserved in the Upper Cretaceous Hell Creek Formation of northeastern Montana, USA. Overall, the dinosaur skeletal assemblages in the Hell Creek Formation (excluding lag-influenced records) consist primarily of subadult or small adult size individuals. Small juveniles and large adults are both extremely rare, whereas subadult individuals are relatively common. We propose that mature individuals of at least some dinosaur taxa either lived in a separate geographic locale analogous to younger individuals inhabiting an upland environment where sedimentation rates were relatively less, or these taxa experienced high mortality before reaching terminal size where late stage and often extreme cranial morphology is expressed. Methodology/Principal Findings Tyrannosaurus skeletons are as abundant as Edmontosaurus, an herbivore, in the upper Hell Creek Formation and nearly twice as common in the lower third of the formation. Smaller, predatory dinosaurs (e.g., Troodon and dromaeosaurids) are primarily represented by teeth found in microvertebrate localities and their skeletons or identifiable lag specimens were conspicuously absent. This relative abundance suggests Tyrannosaurus was not a typical predator and likely benefited from much wider food choice opportunities than exclusively live prey and/or specific taxa. Tyrannosaurus adults may not have competed with Tyrannosaurus juveniles if the potential for selecting carrion increased with size during ontogeny. Conclusions/Significance Triceratops is the most common dinosaur and isolated skulls contribute to a significant portion of this census. Associated specimens of Triceratops consisting of both cranial and postcranial elements remain relatively rare. This rarity may be explained

  4. 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.

  5. 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.

  6. 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., Jr.; 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

  7. 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.

  8. 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.

  9. An integrated 3-D seismic facies analysis of productive Upper Cretaceous and Lower Tertiary Formations of the Willows-Beehive Bend Gas Field, Sacramento Basin, California

    SciTech Connect

    Gabay, S.H.; Link, M.H.; Damuth, J.E.; Kalkomey, C.T. )

    1990-05-01

    An integrated seismic facies analysis of the Willows-Beehive Bend gas field, using three-dimensional seismic data has led to improved identification of reservoir facies, depositional environments, and reservoir parameters. These three-dimensional data were interpreted together with cores, time-based wireline logs, synthetic seismograms, and six regional two-dimensional seismic lines. The three productive formations studied include (1) the Eocene Princeton Gorge fill, which represents a submarine canyon fill; (2) the Upper Cretaceous Kione Formation, which is composed of shelf and deltaic facies; and (3) the mud-rich Upper Cretaceous Forbes Formation, which represents deep water slope and submarine-fan facies. The Princeton Gorge fill consists of an upper shale-dominated facies and a lower sand-rich channel-dominated facies. These channel fills are sinuous, 0.4-0.8 km wide, trend north to south, and have the best reservoir quality of the field. Two facies are recognized in the Kione Formation: a sand-rich deltafront facies and a mud-rich prodelta facies. The delta-front facies shows west to east progradation across the survey area and has good reservoir quality. The prodelta deposits are transitional into the prograding shale-dominated slope deposits of the upper Forbes Formation. This slope facies contains shale-rich submarine-canyon and gully fills that trend northwest to southeast are 0.8-1.6 km wide, and locally contain sinuous sandy channel fills. The middle Forbes Formation consists of two turbidite facies: middle submarine-fan channel/levee complexes and lower fan depositional lobes. The channel/level complexes are sinuous, trend north to south, and are approximately 0.8-2.4 km wide, whereas the depositional lobes are 3-4 km in diameter.

  10. 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

  11. 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.

  12. 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.

  13. 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

    Pittman, Michael; 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

  14. 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

  15. 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

  16. 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

  17. Dinosaur eggshell isotope geochemistry as tools of palaeoenvironmental reconstruction for the upper Cretaceous from the Tremp Formation (Southern Pyrenees)

    NASA Astrophysics Data System (ADS)

    Riera, V.; Anadón, P.; Oms, O.; Estrada, R.; Maestro, E.

    2013-08-01

    The isotopic compositions (δ13C and δ18O) of dinosaur eggshells have been widely used in palaeoenvironmental studies, although the geochemical signatures of eggshells are not usually contrasted with other proxies. In this work, the isotopic signatures of eggshells from a large Maastrichtian succession from the Tremp Formation (Southern Pyrenees, Spain) are compared to those of carbonate pedogenic nodules occurring in the same levels. The isotopic signatures of eggshells vary according to the stratigraphic unit and geographical location. A group of samples from several localities corresponding to eggshells without significant diagenetic imprints has isotopic values differing from the associated nodules; The Late Cretaceous isotopic composition record from the Tremp Fm. is consistent that is, the eggshells have distinct primary signatures preserved. However, the eggshells from another locality, which exhibit neomorphed textures, display isotopic signatures similar to the associated pedogenic carbonate, which suggests a diagenetic isotopic signature and confirms alteration in the eggshells. Both microscopic and geochemical data suggest that an early meteoric diagenesis (pedogenesis) is responsible for the secondary signatures. The δ13C values in the carbonate pedogenic nodules indicate a carbon isotopic composition typical of C3 plants, although the slight difference in δ13C between the palaeosol carbonate of coeval successions may be due to slightly different palaeoenvironmental conditions. The small discrepancy in the δ13C calculated for C3 plants, from carbonate nodules and from eggshells may be because the palaeosol carbonate gives the isotopic composition of the vegetation grown at a local site whereas the δ13C from eggshells is a proxy for the ingested food in the area in which the dinosaurs lived. The oxygen isotopic compositions from palaeosol carbonate nodules have been used for calculation of the air temperature, and we may conclude that the mean air

  18. 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

  19. 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. 

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. Paleosols of the Upper Cretaceous Lower Tertiary Maghra El-Bahari Formation in the northeastern portion of the Eastern Desert, Egypt: Their recognition and geological significance

    NASA Astrophysics Data System (ADS)

    Wanas, H. A.; Abu El-Hassan, M. M.

    2006-01-01

    The Upper Cretaceous/Lower Tertiary Maghra El-Bahari Formation at Gabal Ataqa and Gabal Shabrawet in the northeastern portion of the Eastern Desert of Egypt is subdivided into two informal lithostratigraphic parts: lower and upper. The lower part has common features of alluvial floodplain-dominated deposits with occasional occurrences of crevasse splay deposits. The upper part has sediments typical of marginal lacustrine environments. Both the floodplain and marginal lacustrine deposits exhibit pedogenic features comprising various types of paleosols. Among other soil-forming processes, diversity in the paleosols studied is mainly attributed to paleoclimatic and paleohydrologic changes. The paleosol criteria suggest two climatic regimes, a subhumid-semiarid one succeeded by a semiarid-arid one. The continental depositional environments recognized (floodplain and lacustrine) with their associated paleosols helped in the recognition of a marine regression in the area studied. In a regional perspective, comparison of the data presented in this study with paleosol data spanning the same time period in other localities suggests that the proposed paleoclimatic changes may have been of regional extent.

  5. 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

  6. 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

  7. 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

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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?).

  19. 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).

  20. 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

  1. Facies Variations Along an Ancient Deep-Water Axial Channel Belt: Insights from the Upper Cretaceous Cerro Toro Formation, Magallanes-Austral Basin, Patagonia

    NASA Astrophysics Data System (ADS)

    Malkowski, M. A.; Jobe, Z. R.; Sharman, G.; Graham, S. A.

    2015-12-01

    The Upper Cretaceous Cerro Toro Formation preserves a >150 kilometer long deep-water axial channel belt in the Magallanes-Austral Basin in southern Patagonia. Considerable work over the past decade in the Chilean basin sector reveals a 3.5-8 km wide channel-levee system that transported coarse-grained sediment from north to south via a range of low- to high-density turbidity currents, debris flows, and transitional/hybrid flows. In contrast, the more proximal deposits preserved in the Argentine basin sector to the north received little focus. This study documents new sedimentology, stratigraphy, and U-Pb geochronology from the Cerro Toro Formation in Argentina, allowing for a basin-scale comparison of the timing of deposition, sediment sources, and facies and grain size variability. Two ash beds from the base of the section yield U-Pb zircon ages of 90.4 ± 2 Ma and 88.0 ± 3 Ma, suggesting similar, if not slightly older, ages for the lower Cerro Toro Formation when compared to equivalent units to the south. U-Pb detrital zircon age spectra reveal similar provenance trends along the entire outcrop belt, with peak age populations at 310-260, 160-135, and 110-82 Ma. Preliminary statistical analyses of more than 5700 meters of new and previously published detailed stratigraphic sections suggest that, in general, characteristics such as mean bed thickness and net to gross remain fairly consistent along the outcrop belt. However, the bed thickness distributions are log-normal, and the northern sector has higher maximum bed thickness than the southern sector. There are also gradual variations in the down-system (north to south) proportion of lithofacies. For instance, in the northern (Argentine) sector, lithofacies representing mass wasting processes (e.g., debris flow conglomerates and mass-transport deposits) account for as much as ~80 percent of the stratigraphic thickness, whereas near the southern end of the channel belt, coarse-grained facies are almost entirely

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Effects of climate, tectonics, and sea-level changes on rhythmic bedding patterns in the Niobrara Formation (Upper Cretaceous), US Western Interior

    SciTech Connect

    Laferriere, A.P.; Hattin, D.E.; Archer, A.W.

    1987-03-01

    Regional correlation of interbedded pelagic/hemipelagic limestones and calcareous shales of the Fort Hays Limestone Member of the Niobrara Formation confirms development of at least two levels of cyclicity. Occurrence of time-parallel rhythmically deposited beds that can be correlated over distances exceeding 800 km lends strong support to the hypothesis that these cycles were induced by Milankovitch-type climatic forcing. However, visual observation and Fourier analysis of variations in shale and limestone thickness demonstrate that the pattern of Fort Hays cyclicity lacks regional uniformity. Complications in the cyclic pattern may have resulted from the influence of orbital parameters having differing periodicities. Additionally, departures from simple cyclical patterns resulted from sedimentary effects of the Sevier orogeny and from erosional events associated with sea-level changes. Documentation of thickness variations within the regionally persistent Fort Hays bedding sequence furnishes a basis for fine-scale analysis of Cretaceous crustal movements within the Western Interior seaway.

  7. 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

  8. Magnetostratigraphy of displaced Upper Cretaceous strata in southern California

    NASA Astrophysics Data System (ADS)

    Fry, J. Gilbert; Bottjer, David J.; Lund, Steve P.

    1985-09-01

    A magnetostratigraphic study of Upper Cretaceous marine strata from the Santa Ana Mountains in southern California has identified a Campanian reversed magnetozone. This reversed interval, corresponding to marine magnetic anomaly 33 34 (Chron 33r) of Campanian age, can be correlated with a Campanian reversed magnetozone that has been reported from strata of the Great Valley Sequence in central California. The Late Cretaceous paleolatitude of the Santa Ana Mountains is estimated from this study to be 26.6°N. This is significantly different from the region's expected Cretaceous paleolatitude of 43.8°N as part of the North American stable craton, and indicates that this region (part of the Peninsular Ranges terrane) was 1900 km farther south in Cretaceous time relative to the stable craton. *Present address: Mobil Oil Corp., P.O. Box 900, Dallas, Texas 75221

  9. 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.

  10. 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.

  11. Biostratinomy and facies analysis of the upper Cretaceous oyster storm shell beds of the Duwi formation, Qusseir District, Red Sea Region, Egypt

    NASA Astrophysics Data System (ADS)

    El-Ayyat, Abdalla M.; Kassab, Ahmed S.

    2004-06-01

    The Maastrichtian oyster Lopha villei (Coquand) occurs abundantly in the upper part of the Duwi Formation in the Red Sea region, Egypt. It forms thin undulating sharp-based shell beds that comprise both reclining and encrusting morphotypes of Lopha villei. Bed-by-bed biostratinomic and facies analyses of these shell beds confirm their shallow marine origin and formation by storm events. A tempestite model, explaining the mode of formation and the idealized sequence of events of such storm shell beds, has been inferred.

  12. Oldest termite nest from the Upper Cretaceous of west Texas

    NASA Astrophysics Data System (ADS)

    Rohr, David M.; Boucot, A. J.; Miller, John; Abbott, Maxine

    1986-01-01

    Wood borings and insect frass from the Upper Cretaceous of Texas are interpreted to be the oldest known termite nest, the oldest known termite fecal pellets, and one of the few examples of trace-fossil evidence of social behavior in insects. It illustrates a form of behavioral fixity insofar as coprolite form, feeding habits, and substrate are concerned. *Deceased

  13. 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.

  14. Phase transformations of hydrocarbon accumulations in the Upper Cretaceous complex of the Northeast Caucasus

    SciTech Connect

    Reznikov, A.N.; Yaroshenko, A.A.

    1982-10-01

    The geologic structure and development of the Northeast Caucasus has produced a complex distribution of hydrocarbons in different phases throughout Upper Cretaceous deposits. A comprehensive study of the thermobaric conditions in the region are presented so that the patterns of hydrocarbon phase transformations can be identified. In addition the maturation of the geologic formations in the area that led to the oil formation is discussed. (JMT)

  15. 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. PMID:11387472

  16. 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

  17. 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

  18. Paleomagnetism of the Cretaceous Morelos and Mezcala Formations, southern Mexico

    NASA Astrophysics Data System (ADS)

    Molina Garza, Roberto S.; Böhnel, Harald N.; Hernández, Teodoro

    2003-01-01

    A paleomagnetic study of platform-facies carbonate rocks of the mid-Cretaceous Morelos Formation and deep-water carbonate rocks of the overlying Upper Cretaceous Mezcala Formation, sampled at Zopilote canyon, in Guerrero State, southern Mexico, indicates that their characteristic magnetization was acquired contemporaneously with folding of these rocks during the Late Cretaceous Laramide orogeny. The remanence carrier is interpreted to be magnetite, although other mineral phases of high coercivity carry recent secondary overprints. The overall mean is of Dec=323.1° and Inc=36.5° ( k=162.7; α95=2.7°; N=18 sites; 64% unfolding). Comparison with the North America reference direction indicates that this area has experienced a small, yet statistically significant, counterclockwise direction of 19.2±4.0°. Similar rotations are documented in other localities from southern Mexico; rotations are linked to mid-Tertiary deformation associated with the left-lateral strike-slip fault system that accommodated motion of the Chortis and Xolapa blocks.

  19. 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.

  20. Diagenesis and porosity evolution of upper Cretaceous dolomites, northern Egypt

    SciTech Connect

    Holail, H.M.; Lohmann, K.C.

    1988-08-01

    Porosity patterns in the Upper Cretaceous marine carbonate sequence of northern Egypt record a complex history of diagenesis in marine, hypersaline, and meteoric waters. Depositional facies and fabrics suggest an overall upward-shallowing sequence which, in turn, is bounded above by a major pre-middle Eocene unconformity. Associated with this unconformity, subaerial exposure resulted in a regional influx of meteoric waters. In this context, analysis of the paragenetic relationships and geochemical character of diagenetic phases has allowed for unique determination of the timing and environments of porosity evolution within this sequence.

  1. Revision of the Upper Cretaceous rudists from northwestern Peru

    NASA Astrophysics Data System (ADS)

    Philip, Jean; Jaillard, Etienne

    2004-09-01

    Revision of the Upper Cretaceous rudists of northwestern Peru has led to new discoveries and enabled the specification of their taxonomy and stratigraphic locations. Different species have been identified: Biradiolites cf. jamaicensis Trechmann 1924, Radiolites cf. macroplicatus Whitfield 1897, Praebarrettia sparcilirata (Whitfield, 1897) of Late Campanian age, and Macgillavryia nicholasi (Whitfield, 1897) of Middle-Late Maastrichtian age. During the Campanian and Maastrichtian, rudists of Peru show paleobiogeographic affinities with those of the Mexican and Caribbean domains. A paleogeographic route for rudist migrations may have existed at that time along the Caribbean arc and the Curaçao-Ecuador coastline.

  2. 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., Jr.; 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

  3. 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

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. 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

  11. 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.

  12. 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

  13. Petrography, geochemistry and primary origin of spheroidal dolomite from the Upper Cretaceous/Lower Tertiary Maghra El-Bahari Formation at Gabal Ataqa, Northwest Gulf of Suez, Egypt

    NASA Astrophysics Data System (ADS)

    Wanas, H. A.

    2002-08-01

    Field, petrographical, and geochemical studies of the Maghra El-Bahari Formation at Gabal Ataqa in Egypt indicate an occurrence of spheroidal dolomite as a primary precipitate. Petrographically, this dolomite is microcrystalline (10-40 μm in diameter) and lacks any direct or indirect evidence of a precursor mineral. Each dolomite spherule is composed of a cluster of coalesced incomplete rhombohedral sub-units exhibiting a globular body with a hollow core. This dolomite is commonly associated with authigenic palygorskite and gypsum. Based on its associations, the spheroidal dolomite occurs in two modes: (i) siliciclastic-disseminated dolomite and (ii) evaporitic-associated dolomite. On the basis of its elemental and stable isotopic signature, the spheroidal dolomite is subdivided into two types: Type A and Type B. Type A is Ca-rich (with average CaCO 3 and MgCO 3 equal to 58.20 and 39.91 mol%, respectively) and with average Sr=108 ppm, average Na=656 ppm, average Mn=72 ppm, and δ18O ranges from -0.4 to +0.9‰ PDB. Type B, compared with Type A, is nearly stoichiometric (with average CaCO 3 and MgCO 3 equal to 49.32 and 43.75 mol%, respectively) with higher average Sr (508 ppm), average Na (3008 ppm), average Mn (171 ppm), and δ18O (+0.98 to +1.8‰ PDB). Slightly positive values of δ13C (+0.18 to +2.10‰ PDB) are recorded for the two types of dolomite. Type A belongs to the siliciclastic-disseminated dolomite, whereas Type B is of the evaporitic-associated dolomite. It is interpreted that the spheroidal dolomite directly precipitated from a solution that was supersaturated with respect to dolomite components and did not develop by dolomitization of precursor carbonates. Two main sources are suggested for dolomite precipitation: hypersaline water and mixed saline-fresh water.

  14. 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

  15. 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)

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. Diagenesis of upper Cretaceous Teapot sandstones, Powder River basin, Wyoming

    SciTech Connect

    Conner, S.P.; Tieh, T.T.

    1984-04-01

    The Upper Cretaceous Teapot sandstones of Well Draw field, Converse County, Wyoming, are turbidite fan deposits bounded stratigraphically by marine shales. They presently occur from 6360 to 7200 ft (1920 to 2195 m), dipping to the northwest. Cored samples selected from nonbioturbated A bedsets show that the sandstones are fine to very fine-grained feldspathic litharenites. Major authigenic minerals include carbonate cement, quartz overgrowths, and clay minerals. The clay minerals originated either as alteration rims on detrital silicates or as precipitated from pore fluids. Alteration rims typically consist of illite, smectite, mixed layer illite/smectite, and lesser chlorite. Feldspars are altered to kaolinite. Precipitated clays occur as thin, unoriented, grain coating chlorite and kaolinite; pore lining mixed layer illite/smectite and lesser chlorite oriented with (001) normal to the pore wall; and unoriented, poorly crystalline, pore filling chlorite. The diagenetic sequence is: compaction and limited quartz overgrowth development; complete calcite cementation and precipitation of grain-coating clays; dissolution of carbonate cement; precipitation of pore lining and later pore filling clays; and development of second stage quartz overgrowths. Development of silicate alteration rims occurred throughout the diagenetic history. Dissolution of carbonate cement produced the majority of present-day porosity; however, this secondary porosity was reduced by precipitation of clays minerals. In the downdip sandstones, hydrodynamic flow and an increase in the abundance of detrital labile grains have caused an increased abundance of clay mineral precipitates, reducing the reservoir potential. The pore fluids which controlled sandstones diagenesis were likely provided by dewatering and diagenesis of enclosing shales.

  1. Raman investigations of Upper Cretaceous phosphorite and black shale from Safaga District, Red Sea, Egypt

    NASA Astrophysics Data System (ADS)

    Ciobotă, Valerian; Salama, Walid; Vargas Jentzsch, Paul; Tarcea, Nicolae; Rösch, Petra; El Kammar, Ahmed; Morsy, Rania S.; Popp, Jürgen

    2014-01-01

    The mineral composition of the Upper Cretaceous Duwi phosphorite deposits and underlying Quseir Variegated Shale from Safaga district, Red Sea Range, Egypt, was investigated by dispersive and Fourier transformed Raman spectroscopy. The only phosphorous containing mineral detected in the phosphorite deposits was carbonate fluorapatite. Often carbonate fluorapatite appears associated with calcium sulfate and seldom with calcium carbonate in the investigated samples. Iron is present in the form of goethite and pyrite in the phosphorite layer, while pyrite, marcasite and hematite were identified in the Quseir Shale samples. Also, a high amount of disordered carbon was detected in the black shale layers. The Raman results confirm the hypothesis that the formation of the phosphorites took place in a marine environment. During the formation of black shale, the redox conditions changed, with the pH reaching values of 4 or even lower. Diagenetic and weathering transformations had taken place in the phosphorite deposits, calcium sulfate and goethite being products of these types of processes.

  2. 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

  3. 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.

  4. 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.

  5. Magnetostratigraphic correlation of the Upper Cretaceous System in the North Pacific

    NASA Astrophysics Data System (ADS)

    Kodama, K.

    2003-06-01

    Magnetostratigraphic data for Upper Cretaceous sedimentary strata in widely separated regions of the North Pacific, including Japan, Far East Russia and western North America, are reviewed in terms of calibration to the geomagnetic polarity time scale and regional correlation. A series of normal and reversed polarity zones are recognized in the Upper Cretaceous strata in Shikoku and Hokkaido, Japan, and South Sakhalin, Far East Russia. Combined magnetostratigraphic and biostratigraphic correlation has assigned these zones to the Late Cretaceous geomagnetic polarity chrons including C31r through C33r and the Cretaceous long normal interval. Corresponding geomagnetic reversals have been documented from the Upper Cretaceous successions of the Western Interior of North America, in combination with high-resolution ammonite biostratigraphy and radiometric age dates. Biostratigraphy of the Great Valley Sequence in California is also well-defined, but there is only one reversed interval that can be correlated with polarity chron C33r. The most complete record of polarity reversals in South Sakhalin would provide an integrated reference scheme which can be of significant use not only to correlate dissimilar faunal assemblages of disparate regions in the North Pacific, but also to contribute to a global definition of Upper Cretaceous stage boundaries.

  6. 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).

  7. 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).

  8. 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

  9. 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

  10. 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%.

  11. 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

  12. 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.

  13. 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.

  14. 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

  15. Facial evolution and petroleum potential of the upper Cretaceous black shales of southeast Egypt

    SciTech Connect

    Ganz, H.; Luger, P.; Schrank, E.; Brooks, P.W.; Fowler, M.G.

    1988-08-01

    Newly developed and conventional organic and inorganic geochemical and sedimentological techniques and facies parameters resulted in the reconstruction of the depositional environment and an estimation of the resource potential of the upper Cretaceous black shale/phosphorite sequences in southeastern Egypt. The depositional environment is characterized by a broad, shallow shelf which was separated from the continental hinterland by restricted coastal swamps. Depending on structures on the sea floor and depth of the water column, reducing conditions prevailed. The Campanian/Maastrichtian transgression was interrupted by multiple regressive phases which caused intensive reworking of the marine sediments and the enrichment of phosphatic layers. Minor terrestrial influx occurred during the formation of oyster reefs. Open marine conditions in the upper part of the section (Dakhla Shale) indicate prograding marine transgression. The composition of the black shales is very heterogeneous. Generally the beds which yield a high energy potential (up to 6,000 kJ/kg) are only isolated thin layers. However, the average values of a 40-m Dakhla Shale profile indicate that this sediment is an immature, potentially good source rock for oil and might be suited as a raw material for energy and cement production. Since the average trace element contents in the Dakhla Shale are rather low, final leaching of the combustion residue is not worthwhile.

  16. Cenomanian-Coniacian Upper Cretaceous foraminiferal fauna of Lithuania

    NASA Astrophysics Data System (ADS)

    Aleksienė, Agnė

    2010-12-01

    Foraminiferal assemblages form a unique fauna succession from the Cenomanian to Maastrichtian stages in Lithuania; the Cenomanian-Coniacian succession is discussed in this paper. The first Cretaceous planktonic foraminifera species appeared in the Early Cenomanian. The Cenomanian planktonic foraminiferal association consists of the relatively abundant genus Hedbergella. However, Cenomanian planktonic foraminifera are rare compared to benthic; the latter are numerous, and their assemblage contains various calcareous and agglutinated species. As a result of environmental changes, foraminiferal assemblages gradually changed as well. The newly formed deep-water niches in the Turonian allowed spreading the keeled forms of planktonic foraminifera. Taxonomically, Turonian-Coniacian foraminiferal assemblages are mainly composed of species of the following genera: Praeglobotruncana, Helvetoglobotruncana, Dicarinella, Marginotruncana.

  17. Coastal and deltaic sedimentation of Upper Cretaceous Eagle Sandstone: relation to shallow gas accumulations, North-Central Montana

    SciTech Connect

    Rice, D.D.

    1980-03-01

    Depositional environments of the Upper Cretaceous Eagle Sandstone were studied at outcrops along the Missouri River and its southern tributaries from the town of Virgelle southeastward to the mouth of the Judith River in north-central Montana. The Eagle Sandstone is underlain by the Telegraph Creek Formation and overlain by the Claggett Shale, both of Late Cretaceous Age. The basal Virgelle was deposited along an eastwardly prograding coastal-interdeltaic mainland shoreline. The middle member of the Eagle represents coastal-plain deposition. The delta-front sandstone was deposited along a wave-dominated shoreline that prograded over a coastal plain following an overall marine transgression. The upper member lies disconformably on the middle member and is represented by rock types which were deposited in two distinct depositional settings. Interbedded sandstone, siltstone, and shale that exhibit variable bedding types in the northern outcrops probably accumulated in a tidal-flat environment. Natural gas from shallow accumulations in the Eagle Sandstone of the Bearpaw Mountains area is of biogenic origin and was probably generated in the surrounding shales during Late Cretaceous time. Although gravity-induced faults formed after the gas generation provide the final trapping mechanism, the initial control for entrapment was stratigraphic. Most of the early generated gas has remigrated into separate, discrete structural traps where porous reservoirs are developed; some of the gas may have been selectively sealed in origin stratigraphic traps. 16 figures, 1 table.

  18. 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

  19. 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. PMID:21437388

  20. 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.

  1. 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).

  2. Raman investigations of Upper Cretaceous phosphorite and black shale from Safaga District, Red Sea, Egypt.

    PubMed

    Ciobotă, Valerian; Salama, Walid; Vargas Jentzsch, Paul; Tarcea, Nicolae; Rösch, Petra; El Kammar, Ahmed; Morsy, Rania S; Popp, Jürgen

    2014-01-24

    The mineral composition of the Upper Cretaceous Duwi phosphorite deposits and underlying Quseir Variegated Shale from Safaga district, Red Sea Range, Egypt, was investigated by dispersive and Fourier transformed Raman spectroscopy. The only phosphorous containing mineral detected in the phosphorite deposits was carbonate fluorapatite. Often carbonate fluorapatite appears associated with calcium sulfate and seldom with calcium carbonate in the investigated samples. Iron is present in the form of goethite and pyrite in the phosphorite layer, while pyrite, marcasite and hematite were identified in the Quseir Shale samples. Also, a high amount of disordered carbon was detected in the black shale layers. The Raman results confirm the hypothesis that the formation of the phosphorites took place in a marine environment. During the formation of black shale, the redox conditions changed, with the pH reaching values of 4 or even lower. Diagenetic and weathering transformations had taken place in the phosphorite deposits, calcium sulfate and goethite being products of these types of processes. PMID:24036306

  3. 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., Jr.; 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.

  4. Formation evaluation in the Texas Cretaceous chalk trend

    SciTech Connect

    Frost, E. Jr.; Stedman, D.; Fertl, W.H.

    1982-06-01

    Skilled formation evaluation is essential to economic well completions in the Cretaceous carbonate trend of South and Central Texas. The Austin chalk and Buda lime wells within this trend are known for high initial production rates followed by rapid production decline probably due to completion in zones of insufficient porosity and permeability. Therefore, the proper use of geophysical wireline data to locate fractures and determine fracture quality and hydrocarbon potential prior to setting casing is an essential element in evaluating the economics of any given well. This work details current successful evaluation procedures utilized in the trend. 11 refs.

  5. 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.

  6. 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).

  7. 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

  8. 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.

  9. 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.

  10. 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

  11. The territory of Georgia and surrounding countries in the Upper Cretaceous: paleomagnetic data

    NASA Astrophysics Data System (ADS)

    Asanidze, B. Z.; Adamiya, Sh. A.; Tabagua, I. A.; Odikadze, N. Sh.

    2009-07-01

    Paleomagnetic researches of the Upper Cretaceous rocks, collected from 24 cross-sections (530 samples) of Georgia have shown that only nine samples are suitable for the paleotectonic problem to be solved. The method of thermomagnetic cleaning was used for the paleomagnetic directions of these rocks to be determined. Magnetic-mineralogical data and the tests of paleomagnetic accuracy have proved the ancient age of the stable part of the natural remnant magnetization (NRM) that is close to the initial one. The study results have demonstrated that the position of the areas studied in the Upper Cretaceous time was located 11°-18° southward from their modern latitudinal position; the distance between structures of the Great Caucasus and Trans-Caucasus was 10°-14°. The wide variations of the paleoinclinations are connected with the local turns of tectonic blocks

  12. 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.

  13. 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.

  14. 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.

  15. 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

  16. A new hermit crab (Anomura, Paguroidea) from the upper Albian (Cretaceous) of Annopol, Poland.

    PubMed

    Fraaije, René H B; Van Bakel, Barry W M; Jagt, John W M; Machalski, Marcin

    2015-01-01

    A new diogenid paguroid, Paguristes liwinskii sp. nov., is described from upper Albian phosphorite-bearing deposits near Annopol, along the east bank of the River Vistula (Wisła), east-central Poland. This new species constitutes an additional example of Early-Mid-Cretaceous macrofaunal shift, from marine reefal limestone to siliciclastic facies, triggered by the worldwide radiation of planktonic organisms. The species described here is the earliest known member of the genus Paguristes, previously recorded from the upper Santonian/lower Campanian to the Recent. PMID:25947874

  17. Genesis of Upper Cretaceous marl-limestone bedding, Alabama

    SciTech Connect

    King, D.T. Jr. )

    1990-09-01

    In Alabama, marl-limestone bedding couplets and correlative coeval prograding clastic barrier-shoreline facies occur in the upper 20 m of a high-stand systems tract within the lower Campanian Mooreville-Demopolis depositional sequence. The Mooreville-Demopolis depositional sequence is terminated by a type-2 unconformity biostratigraphically dated at about 80 million years before present. Based on estimates using long-term sedimentation rate, the average periodicity of the marl-limestone couplets is approximately 100,000 years. Taken at face value, the apparent 100,000-year periodicity would suggest a climate-forced (or Milankovitch) origin of the marl-limestone couplets owing to cycles of productivity and dilution. However, significant variations in marl-limestone couplet thickness (ranging from less than 1 m to several meters) both within and between couplets suggests that average periodicity is not a meaningful figure with respect to these couplets. Further, climate-forcing is not favored because coarse clastic material fines upward in the marl beds and the petrography of the beds shows that the primary mode of biochemical deposition switched from pelagic nannofossils (in the marl) to benthic algal calcispheres (in the limestone). In order to adequately explain the petrographic and thickness observations, changing relative sea level is suggested as a viable hypothesis. Tectonic effects related directly to early stages of the Laramide orogeny (about 80 million years before present) may have affected relative sea level as far east as the Gulf Coastal Plain, thus producing the marl-limestone sequences. Marl-limestone sequences may reflect either short-term buildup and relaxation of intraplate stresses or short-term eustatic changes that resulted from slight variations in Farallon spreading rates.

  18. 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.

  19. 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

  20. 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

  1. 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.

  2. Paired Magnetic Susceptibility Cyclostratigraphy and Revised Magnetostratigraphy with Late Cretaceous Euler Pole from Forbes Formation, Sand Creek, Sacramento Valley, California

    NASA Astrophysics Data System (ADS)

    Slotznick, S. P.; Raub, T.; Mitchell, R. N.; Ward, P. D.; Kirschvink, J. L.

    2012-12-01

    Magnetostratigraphy in Upper Cretaceous rocks of Sacramento Valley has successfully complemented biostratigraphy for correlating between circum-Pacific basins. Most paleomagnetic measurements were done pre-1990 using alternating field demagnetization only, due to oxidation accompanying thermal demagnetization. We present paleomagnetic data collected via thermal demagnetization in a flowing nitrogen atmosphere from 223 cores collected over a 130m of section of Forbes Formation in Sand Creek, CA spanning upper Dobbins Shale, Forbes Unit 2 and lower Unit 3. These results uniformly indicate Reversed Chron 33R, contra previously published magnetostratigraphy of the area (Ward et al. 1983, Verosub et al. 1989). Additionally, these paleomagnetic results yield a tightly-constrained paleolatitude for Forbes Formation of 31±3°, which varies significantly from previous APWP models ca. 83 Ma (Besse and Courtillot, 2002) suggesting an unaccounted-for deficiency in reconstructions of North America at this time. This discrepancy might indicate an inaccurate cratonic reference pole, underestimated intrabatholithic or distributed plate boundary deformation, and/or true polar wander. As opposed to other units yielding anomalous late Cretaceous paleolatitudes from outboard terranes, Forbes Formation in Sacramento Valley laps unambiguously onto the North American continent. A 25m AW34 core was collected using a Winkie drillrig near the top of Dobbins Shale Mbr. Paleomagnetic measurements on subsamples from the Winkie core, unaffected by surface weathering, combine with the surficial dataset, and we propose a new set of Euler pole solutions potentially quantifying Basin and Range extension and late Cretaceous intra-Sierran shear. Through magnetic susceptibility measurements of the Winkie core, we were able to resolve orbital cycles which, paired with rock magnetic measurements, constrain basin subsidence and sedimentation rate off the Sierran arc at its age of termination. Re

  3. 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.

  4. 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.

  5. Cap-shaped gastropods from Upper Jurassic and Lower Cretaceous deposits of northern East Siberia

    NASA Astrophysics Data System (ADS)

    Guzhov, A. V.; Zakharov, V. A.

    2015-09-01

    Cap-shaped gastropods are first identified in Upper Jurassic and Lower Cretaceous sections of northern East Siberia. They belong to three new genera of the subclass Pectinibranchia ( Boreioconus gen. nov., Nixepileolus gen. nov., and Taimyroconus gen. nov.), which are identified at the species level ( B. bojarkensis sp. nov., N. depressus sp. nov., T. zakharovi sp. nov.), and several species with the open nomenclature. The genus Taimyroconus attributed to the family Calyptraeidae is considered as an ancestral form of the genus Crepidula. The stratigraphic position of each taxon is determined for several sections. The facies confinement, habitat conditions, and ethology of defined genera are considered with the analysis of their geographic distribution.

  6. 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.

  7. 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

  8. Turbidite fans in Upper Cretaceous Pierre Shale, Eagle Basin, Colorado: a new reservoir facies

    SciTech Connect

    Krystinik, L.F.

    1983-03-01

    Two fans intercalate with the Upper Cretaceous Pierre Shale and form cliffs over more than 10 mi (16 km) of continuous outcrop in the Eagle basin, north of Walcott, Colorado. Both units exhibit progradational sequences typical of turbidite fans. A common vertical succession of sedimentary structures consists of starved ripples, flat-bottomed ripple beds, thin flat beds grading into ripples of climbing ripples, and amalgamated flat beds. Massive to graded beds are rare and occur only in the upper part of each sandstone body. Associated sedimentary features include parting lineation, grooves, prod marks, mud chips, contorted bedding, and flute casts. Broad, low-relief channels occur at the top of the lower, more well-developed sequence. The sedimentary structures described correlate well with accepted models for turbidite-fan sedimentation. Alternative interpretations of these laterally continuous, progradational sandstone bodies might include deposition in a distal shoreface or offshore bar environment. Hummocky cross-stratification and large-scale cross-stratified bed forms are not common in the sequence, as would be expected in a shoreface or marine-bar environment. Turbidite-fan deposits similar to those studied could be economically significant because of their extreme lateral continuity, updip seals, intercalation with hydrocarbon source rock, and possible overpressuring. The presence of submarine fans within the Cretaceous Western Interior seaway may increase significantly the hydrocarbon potential of previously unexplored, shaly portions of the basin.

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. Tertiary age for upper Nubian sandstone formation, central Sudan

    SciTech Connect

    Prasad, G.; Lejal-Nicol, A.; Vaudois-Mieja, N.

    1986-02-01

    In central and northern Sudan, oil exploration is now active in the basins containing sediments of the Nubian Sandstone Formation. On the evidence of planned pipeline construction, significant volumes of oil appear to have been discovered in southwestern Sudan. A newly discovered flora from the upper Nubian Sandstone Formation near Khartoum in central Sudan is Tertiary in age. The flora is well preserved, and comprises leaves, flowers, and fruits, many not yet described. At the generic level, they are comparable to forms that are known fro the Eocene to Miocene. Aquatic plants indicate a lacustrine paleoenvironment; humid tropical forests thrived on the lakeshores. The Nubian Sandstone Formation of Sudan had been considered to be entirely of Cretaceous age; this new flora shifts the upper boundary into the Tertiary. The Tertiary Hudi Chert, found in scattered outcrops in the region of Atbara, was considered to overlie the Nubian Sandstone Formation. The authors suggest that the Hudi Chert is partly age equivalent to the Tertiary upper Nubian Sandstone at Jebel Mudaha.

  14. Diagenetic controls on reservoir heterogeneity in Cretaceous Mishrif Formation in Zeta-1 well, offshore Dubai

    SciTech Connect

    Videtich, P.E.; McLimans, R.K.; Frank, H.J.

    1989-03-01

    The Zeta-1 well tested a thickened lens of the Cretaceous Mishrif Formation located east of Fateh field in offshore Dubai, United Arab Emirates. Initial petrographic study of Mishrif core showed it to be a homogeneous, mollusk-rudist packstone that apparently underwent similar diagenesis throughout. However, geochemical analyses of the ore identified a horizon where sharp changes in the elemental and stable carbon isotope compositions occur. The authors interpret those changes to be due to a discontinuity that divides the packstone into upper and lower units. There is a marked change in porosity coincident with the discontinuity from 13% in the lower unit to 24% in the upper unit. Evidence for oil migration at Zeta-1 is retained in the form of oil fluid inclusions trapped within calcite cements. However, oil inclusions are found only in cements near or above the discontinuity. This suggests that oil migration was confined to the upper packstone, whereas cementation continued unrestricted in the lower packstone, resulting in diminished porosity. The lack of an updip seal is the apparent reason why commercial quantities of oil did not accumulate at Zeta-1. Geothermometry studies of fluid inclusions entrapped in late blocky calcite spar that occludes much of the porosity indicate that the cement originated at depth from a high-density brine, consistent with the above scenario. Thus, the heterogeneity in the reservoir rock is related to early diagenesis, controlled in part by the discontinuity, deep burial cementation, and migration of oil.

  15. Sudden Extinction of the Dinosaurs: Latest Cretaceous, Upper Great Plains, U.S.A.

    NASA Astrophysics Data System (ADS)

    Sheehan, Peter M.; Fastovsky, David E.; Hoffmann, Raymond G.; Berghaus, Claudia B.; Gabriel, Diane L.

    1991-11-01

    Results of a three-year field study of family-level patterns of ecological diversity of dinosaurs in the Hell Creek Formation of Montana and North Dakota show no evidence (probability P < 0.05) of a gradual decline of dinosaurs at the end of the Cretaceous. Stratigraphic reliability was maintained through a tripartite division of the Hell Creek, and preservational biases were corrected for by comparison of results only from similar facies as well as through the use of large-scale, statistically rigorous survey and collection procedures. The findings are in agreement with an abrupt extinction event such as one caused by an asteroid impact.

  16. Sudden extinction of the dinosaurs: latest Cretaceous, upper Great Plains, USA.

    PubMed

    Sheehan, P M; Fastovsky, D E; Hoffmann, R G; Berghaus, C B; Gabriel, D L

    1991-11-01

    Results of a three-year field study of family-level patterns of ecological diversity of dinosaurs in the Hell Creek Formation of Montana and North Dakota show no evidence (probability P < 0.05) of a gradual decline of dinosaurs at the end of the Cretaceous. Stratigraphic reliability was maintained through a tripartite division of the Hell Creek, and preservational biases were corrected for by comparison of results only from similar fades as well as through the use of large-scale, statistically rigorous survey and collection procedures. The findings are in agreement with an abrupt extinction event such as one caused by an asteroid impact. PMID:11536489

  17. 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

  18. 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

  19. Provenance of conglomerate clasts from Upper Cretaceous Kuskokwim group, southwest Alaska

    SciTech Connect

    Crowder, K.L.; Decker, J.

    1985-04-01

    The predominantly Upper Cretaceous (Albian to Coniacian) Kuskokwim Group consists of marine turbidites and subordinate fluvial and shallow marine strata, deposited in an elongate southwest-trending basin covering over 70,000 km/sup 2/ in southwestern Alaska. In the Sparrevohn and Cairn Mountain areas of the Lime Hills A-7 and A-8 quadrangles, fluvial, inner fan, middle fan, and outer fan facies are stacked with distal facies over proximal facies by northwest vergent thrust faults. Inner fan pebble-to-cobble conglomerate and pebbly sandstone were deposited as submarine grain flows up to 10 m thick containing reversely graded bases and normally graded tops. Clasts from these conglomeratic deposits are predominantly sedimentary rock fragments - particularly sandstone, siltstone, and argillite - originally through to have been derived from the nearby Jurassic and Lower Cretaceous flysch (Kihiltna terrane). Detailed examination of these clasts, however, indicate that they contain as minor constituents Paleozoic coral, oolitic limestone, algal boundstone, radioarian chert, and mafic, intermediate, and felsic volcanic rocks, most likely derived from the adjacent Nixon Fork, Killinger, and Mystic terranes. Sandstone clasts are arkosic (Q25-F37-L38, n = 7) and contain subequal amounts of K-feldspar and plagioclase. Sand grains within these clasts are moderately sorted, subrounded, and have presolved contacts. Similar arkosic rocks have been described from the Killinger terrane of the McGrath quadrangle and are the most likely source for the pebbles and cobbles within the Kuskokwim Group.

  20. 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

  1. 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

  2. Submarine-fan facies associations of the Upper Cretaceous and Paleocene Gottero Sandstone, Ligurian Apennines, Italy

    USGS Publications Warehouse

    Nilsen, T.H.; Abbate, E.

    1984-01-01

    The Upper Cretaceous and Paleocene Gottero Sandstone was deposited as a small deep-sea fan on ophiolitic crust in a trench-slope basin. It was thrust northeastward as an allochthonous sheet in Early and Middle Cenozoic time. The Gottero, as thick as 1500 m, was probably derived from erosion of Hercynian granites and associated metamorphic rocks in northern Corsica. Outcrops of inner-fan channel, middle-fan channel and interchannel, outer-fan lobe, fan-fringe, and basin-plain facies associations indicate that the depositional model of Mutti and Ricci Lucchi for mixed-sediment deep-sea fans can be used. The original fan had a radius of 30 to 50 km. ?? 1984 Springer-Verlag New York Inc.

  3. New paleomagnetic results from the Upper Cretaceous red marls of the Pieniny Klippen Belt, Western Carpathians: Evidence for general CCW rotation and implications for the origin of the structural arc formation

    NASA Astrophysics Data System (ADS)

    Márton, Emő; Grabowski, Jacek; Plašienka, Dušan; Túnyi, Igor; Krobicki, Michał; Haas, János; Pethe, Mihály

    2013-04-01

    The Pieniny Klippen Belt (PKB) is a narrow arcuate structure separating the Central and Outer Western Carpathians formed during several Cenozoic deformational stages. The primary aim of this study was to obtain paleomagnetic constraints for the mechanism of formation of the arc. We investigate Albian-Santonian red pelagic marls from 14 localities, distributed along a strike length of ca. 400 km. AMS measurements reveal a pattern characteristic of weakly deformed sedimentary rocks and magnetic lineations do not correlate with the general strike of the PKB. Paleomagnetic analysis revealed well defined hematite-based ancient magnetization components at 13 localities, which are dated using fold- and inclination tests. A within-locality fold test is negative for two localities exhibiting large CCW rotations of similar magnitude situated at the two ends of the PKB. Remanences of pre-folding age were documented for 11 localities, with an overall mean paleomagnetic direction of D = 311°, I = 53°, and α95 = 11°. The indicated general CCW rotation most probably took place during the Miocene, together with Western Central and Outer Carpathians. Paleolatitudes for the PKB indicate a considerable separation from the southern margin of stable Europe leaving space for coordinated rotation. A paleomagnetic oroclinal test involving all localities with primary magnetizations was negative. When localities with monoclinal steep dips are omitted due to possible declination bias, the overall mean paleomagentic direction does not change significantly, but correlation is observed between the general trend of the PKB and the paleomagnetic declinations. Thus, we conclude that the present shape of the arc can be partly due to oroclinal bending. This must have happened before Oligocene since paleomagnetic declinations for neighboring Paleogene basins in the Central and Outer Western Carpathians reveal a uniform CCW rotation of ca. 50° magnitude, irrespective of the position of the

  4. 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.

  5. 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.

  6. Dinoflagellates: Fossil motile-stage tests from the upper cretaceous of the Northern New Jersey coastal plain

    USGS Publications Warehouse

    May, F.E.

    1976-01-01

    Fossil dinoflagellate tests have been considered to represent encysted, nonmotile stages. The discovery of flagellar porelike structures and probable trichocyst pores in the Upper Cretaceous genus Dinogymnium suggests that motile stage tests are also preserved as acid-resistant, organic-walled microfossils.

  7. The overthrusted Zaza Terrane of middle Cretaceous over the North American continental carbonate rocks of upper Jurassic-Lower Cretaceous age - relationships to oil generation

    SciTech Connect

    Echevarria Rodriguez, G.; Castro, J.A.; Amaro, S.V.

    1996-08-01

    The Zaza Terrane is part of the Caribbean plate thrust over the southern edge of the North American basinal and platform carbonate rocks of upper Jurassic-Lower Cretaceous age. Zaza Terrane are volcanic and ophiolitic rocks of Cretaceous age. The ophiolites are mostly serpentines which behave as reservoirs and seals. All Cuban oil fields are either within Zaza Terrane or basinal carbonates underneath, or not far away to the north of the thrust contacts. It appears that the overthrusting of the Zaza Terrane caused the generation of oil in the basinal carbonate source rocks underneath, due to the increase of rock thickness which lowered the oil window to a deeper position and increased the geothermal gradient. Oil generation was after thrusting, during post-orogenic. API gravity of oil is light toward the south and heavy to very heavy to the north. Source rocks to the south are probably of terrigenous origin.

  8. 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.

  9. Sequence stratigraphy of the lower Upper Cretaceous Elbtal Group (Saxony, Germany): new data from Middle Cenomanian-Upper Turonian outcrops and boreholes

    NASA Astrophysics Data System (ADS)

    Richardt, Nadine; Wilmsen, Markus

    2013-04-01

    The formations of the Saxonian Cretaceous have been combined in the so-called Elbtal Group. Their sedimentation took place in a terrestrial to neritic environment palaeogeographically located between the Mid-European Island (MEI) in the SW and the Lusatian Massif in the NE. The through extended from the narrow marine strait of Saxony into the broad Bohemian Cretaceous Basin (Czech Republic) further to the SE. Deposition has been dominated by marine siliciclastics that accumulated on a graded shelf with basically three main facies zones: the coarse-grained nearshore zone ("Küstensandsteinzone"), the transitional zone ("Faziesübergangszone") and the fine-grained marly offshore facies zone ("Plänerfazies"). In general, transgression proceeded in late Early Cenomanian times from the N. Relictic remains of these marine bioclastic conglomerates (Meißen Formation) only occur in the northwesternmost area of the basin around Meißen and are related to the highstand of the depositional sequence Cenomanian 3 (DS Ce 3). After a short stratigraphic gap, onlap continued in the Middle Cenomanian with the following Niederschöna Formation consisting of coarse-grained braided river deposits at the base grading via carbonaceous point-bar cycles of a meandering river system into bioturbated, partly cross-bedded estuarine sediments toward the top. These sediments record DS Ce 4 and are capped by a paleosol. Sedimentation of DS Ce 5 started with a renewed transgressional pulse initiating the Late Cenomanian. The strata consist of bioturbated, cross-bedded predominantly fine- to medium-grained quartz sandstones with some shell-rich horizons corresponding to the Oberhäslich Formation. The unconformably overlying DS Tu 1 comprises the uppermost Cenomanian Dölzschen Formation and the Lower Turonian part of the Schmilka Formation. The onset of this depositional sequence is marked by a major transgression ("plenus Transgression) drowning the remaining pre-transgression topography

  10. Stratigraphy, sedimentology and tectonic evolution of the Upper Cretaceous/Paleogene succession in north Eastern Desert, Egypt

    NASA Astrophysics Data System (ADS)

    El Ayyat, Abdalla M.; Obaidalla, Nageh A.

    2013-05-01

    The stratigraphy, sedimentology and syn-depositional tectonic events (SdTEs) of the Upper Cretaceous/Paleogene (K-P) succession at four localities in north Eastern Desert (NED) of Egypt have been studied. These localities are distributed from south-southwest to north-northeast at Gebel Millaha, at North Wadi Qena, at Wadi El Dakhal, and at Saint Paul Monastery. Lithostratigraphically, four rock units have been recorded: Sudr Formation (Campanian-Maastrichtian); Dakhla Formation (Danian-Selandian); Tarawan Formation (Selandian-Thanetian) and Esna Formation (Thanetian-Ypresian). These rock units are not completely represented all over the study area because some of them are absent at certain sites and others have variable thicknesses. Biostratigrapgically, 18 planktonic foraminiferal zones have been recorded. These are in stratigraphic order: Globotruncana ventricosa Zone (Campanian); Gansserina gansseri, Contusotruncana contusa, Recimguembelina fructicosa, Pseudohastigerina hariaensis, Pseudohastigerina palpebra and Plummerita hantkenenoides zones (Maastrichtian); Praemurica incostans, Praemurica uncinata, Morozovella angulata and Praemurica carinata/Igorina albeari zones (Danian); Igorina albeari, Globanomanlina pseudomenradii/Parasubbotina variospira, Acarinina subsphaerica, Acarinina soldadoensis/Globanomanlina pseudomenardii and Morozovella velascoensis zones (Selandian/Thantian); and Acarinina sibaiyaensis, Pseudohastigerina wilcoxensis/Morozovella velascoensis zones (earliest Ypresian). Sedimentologically, four sedimentary facies belts forming southwest gently-dipping slope to basin transect have been detected. They include tidal flats, outer shelf, slumped continental slope and open marine hemipelagic facies. This transect can be subdivided into a stable basin plain plus outer shelf in the extreme southwestern parts; and an unstable slope shelf platform in the northeastern parts. The unstable slope shelf platform is characterized by open marine hemipelagic

  11. 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.

  12. 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.

  13. Paleocurrent analysis of Cretaceous Mitchell Formation, north-central Oregon

    SciTech Connect

    Sandefur, C.A.; Fisk, L.H.

    1989-03-01

    Cretaceous sedimentary rocks in north-central Oregon contain both potential petroleum source rocks and reservoir rocks. Thus, determining their extent under the cover of Tertiary volcanics is of great importance to future petroleum exploration in the southern portion of the Columbia basin. Limited studies of sediment transport direction have been previously reported by several workers; however, no conclusive evidence was obtained. This study was undertaken to resolve the differences in the previously presented interpretations. The outcropping sedimentary sequence represents part of a subsea fan complex consisting of fan-apron facies turbidites and mudstones (Hudspeth mudstone facies) and channel-facies conglomerates and sandstones (Gable Creek conglomerate facies). Paleocurrent data derived from sole marks, flute casts, clast imbrication, and alignment of elongate plant fragments document that sediment transport was primarily from the south-southeast toward the north-northwest. Thus, the greatest potential for petroleum production from Cretaceous sediments in north-central Oregon lies to the west and northwest of the Mitchell area in northeast-southwest elongated rift basins. These basins, presumably containing thick accumulations of Cretaceous marine sediment fill, are now evidenced by large gravity and magnetic lows.

  14. Depositional, diagenetic, thermal, and maturation histories of Cretaceous Mishrif Formation, Fateh Field, Dubai

    SciTech Connect

    Videtich, P.E.; McLimans, R.K.; Watson, H.K.S.; Nagy, R.M.

    1988-10-01

    Rudist reef associated limestones comprising the Cretaceous Mishrif Formation are the major reservoirs in Fateh field, a giant oil field in offshore Dubai. In this study, Mishrif cores from four wells on the western flank of the field were examined to gain insights into the depositional, diagenetic, thermal, and maturation histories of the Mishrif Formation in this area. The wells lowest on the west flank contain relatively deep-water, lower fore-reef facies bounded by two erosional unconformities. The upper unconformity marks the Laffan-Mishrif contact and extends over Fateh field throughout the region. In Fateh field, the lower intra-Mishrif unconformity has been identified only on the western flank, but is probably present in other locations low on the Fateh structure. The identification of the lower unconformity indicates two cycles of Mishrif sedimentation. The cycles are related to deep-seated salt movement and epeiric sea level changes. Fluid inclusion data, maturation calculations, and burial history modeling indicate that the timing of cementation by blocky calcite spar and oil migration were approximately synchronous and occurred during the Oligocene to Miocene. 16 figures, 2 tables.

  15. Paleomagnetism of Upper Cretaceous red-beds from the eastern Qiangtang Block: Clockwise rotations and latitudinal translation during the India-Asia collision

    NASA Astrophysics Data System (ADS)

    Tong, Ya-Bo; Yang, Zhenyu; Gao, Liang; Wang, Heng; Zhang, Xu-Dong; An, Chun-Zhi; Xu, Yin-Chao; Han, Zhi-Rui

    2015-12-01

    High-temperature magnetization component was isolated between 600 °C and 680 °C from Upper Cretaceous red-beds in the Mangkang area, in the eastern end of the Qiangtang Block, Tibetan Plateau. The tilt-corrected site-mean direction is Ds/Is = 51.3°/56.1°, with k = 31.0 and α95 = 6.5°, corresponding to a paleolatitude of 36.7 ± 6.7°N. Positive fold and reversal tests indicate a primary magnetization. Inclination shallowing tests show that inclination bias is not present in the Upper Cretaceous red-beds of the Qiangtang Block that might induce through depositional and/or compaction process. However, previous paleomagnetic data obtained from Cretaceous and Paleocene-Eocene volcanic rocks show that the paleolatitudes of the Lhasa Block were 17.1 ± 3.3°N and 22.3 ± 4.4°N, respectively, and 28.7 ± 3.7°N for the central Qiangtang Block yielded from Eocene volcanic rocks. These results show that there was a ∼10° latitudinal discrepancy between the Lhasa Block and Qiangtang relative to Eurasia. However, the Mangkang area of the southeastern Qiangtang Block experienced ∼3.2 ± 7.8° to 7.3 ± 5.2° southward extrusion and ∼40° clockwise rotational movement relative to Eurasia since the Cretaceous, which coincided with the Early Cenozoic rotational extrusion of the Indochina and Shan-Thai Blocks. The crustal deformation in the eastern Qiangtang Block should have been caused by the Indian Plate penetrating into Eurasia in the eastern end of Tibetan Plateau and the formation of the Eastern Himalaya Syntaxis since the Oligocene/Miocene.

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. Pressure solution and microfracturing in primary oil migration, Upper Cretaceous Austin Chalk, Texas Gulf Coast

    SciTech Connect

    Chanchani, J.; Berg, R.R.; Lee, C.I.

    1996-09-01

    The Upper Cretaceous Austin Chalk is a well known source rock and fractured reservoir in the Gulf Coast. Production is mainly from tectonic fractures, and the mechanism by which oil migrated from the matrix into the fractures is poorly understood. Microfracturing due to oil generation offers a possible explanation for the mechanism of the primary migration of oil in the Austin Chalk. Petrographic study shows that the major components of the primary migration system are the solution seams and the associated microfractures. Pressure solution is manifest as centimeter to millimeter-scale solution seams and smaller microseams. The solution seams are composites formed by the superposition of the smaller microseams. A significant amount of organic matter was concentrated in the seams along with other insoluble residue. Swarms of horizontal microfractures, many of them filled with calcite and other residue, are associated with the seams. Vertical, tectonic fractures that constitute the reservoir porosity, intersect the solution seams. Pressure solution concentrated organic matter within the solution seams and oil was generated there. It is postulated that the accompanying increase in fluid volume raised the pore pressures and fractured the rock. The newly created microfractures were avenues for migration of fluids from the seams, perhaps by microfracture propagation.

  6. An Upper Jurassic-Lower Cretaceous carbonate platform from the Vâlcan Mountains (Southern Carpathians, Romania): paleoenvironmental interpretation

    NASA Astrophysics Data System (ADS)

    Michetiuc, Mihai; Catincuţ, Camelia; Bucur, Ioan I.

    2012-02-01

    The results of a biostratigraphic and sedimentological study of the Upper Jurassic-Lower Cretaceous limestones cropping out in the southern sector of the Vâlcan Mountains in Romania are presented, including the definition of microfacies types, fossil assemblages and environmental interpretation. Six microfacies types (MFT 1-MFT 6) have been identified, each of them pointing to a specific depositional environment. The deposits are characteristic of a shallow carbonate platform. They contain normal marine or restricted marine facies deposited in low or high energy environments from the inner, middle and outer platform. The age attribution of these deposits (Late Jurassic to Berriasian-Valanginian-?Hauterivian, and Barremian) is based on foraminiferal and calcareous algae associations. The micropaleontological assemblage is exceptionally rich in the Vâlcan Mountains and brings new arguments for dating the Upper Jurassic-Lower Cretaceous limestones in this area.

  7. Marl-limestone bedding and sea level change, Upper Cretaceous of Alabama coastal plain

    SciTech Connect

    King, D.T. Jr. )

    1990-05-01

    Primary Upper Cretaceous marl-limestone sequences in Alabama are superficially similar to sequences interpreted as orbitally forced (Milankovitch) cycles with apparent 100,000 yr periodicity. However, key petrographic and stratigraphic observations cast doubt on a Milankovitch interpretation of the Alabama sequences. These observations include (1) varying thickness from less than 1 m to several meters within marl-limestone sequences, (2) fining upward among the coarse clastic grain sizes within each marl-limestone sequence, and (3) switching the primary mode of biochemical deposition between the marl and limestone beds (e.g., the limestone bed in each marl-limestone sequence contains abundant benthic algal grains (over 50%), whereas the marl contains only pelagic nannofossils). Periodicity is not supported by observed thickness variations and the other petrographic and stratigraphic observations previously noted are inconsistent with cyclic (Milankovitch) productivity/dilution genesis of bedding. In Alabama, marl-limestone sequences and correlative coeval prograding clastic barrier-shoreline facies comprise the upper 20 m of a highstand systems tract within the lower Campanian Mooreville-Demopolis depositional sequence. A sequence-bounding (type 2) stratigraphic break, which has been biostratigraphically correlated with the global sea level drop at 80 Ma occurs at the top of the 20 m marl-limestone interval. Tectonic effects related to the early stages of the Laramide orogeny (about 80 Ma) affected short-term relative sea level thus producing the marlstone sequences. In this hypothesis, the marl-limestone sequences reflect either short-term buildup and relaxation of intraplate stresses or short-term eustatic changes that resulted from slight variations in Farallon spreading rates.

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. The Frontier Formation and mid- Cretaceous orogeny in the foreland of southwestern Wyoming.

    USGS Publications Warehouse

    Merewether, E.A.

    1983-01-01

    Tectonism in SW Wyoming and adjoining areas, and fluctuations of sea level in the central USA during the mid-Cretaceous are represented by the regional stratigraphy of the Frontier Formation. The Frontier consists mainly of clastic rocks that were deposited in marine and nonmarine environments during latest Albian, Cenomanian, Turonian, and Coniacian time. -from Author

  13. 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

  14. 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.

  15. Nuurcala obesa sp. n. (Blattida, Caloblattinidae) from the Lower Cretaceous Yixian Formation in Liaoning Province, China

    PubMed Central

    Wang, Chongda; Ren, Dong

    2013-01-01

    Abstract Nuurcala obesa sp. n., in the cockroach family Caloblattinidae, is described from the Lower Cretaceous Yixian Formation (Liaoning Province, China) based on a combination of differential characters of fore- and hind wing venation, colouration and body structures. Systematically, Nuurcala (Vršanský, 2003), known from the Cretaceous sediments of Bon Tsagaan and Khurilt, Mongolia, is closely related to other genera of Caloblattinidae known from the Jurassic and Cretaceous localities in other parts of Asia. PMID:23950675

  16. 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

  17. 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. PMID:26039066

  18. Turonian (Upper Cretaceous) inoceramid bivalves of the genus Mytiloides from the Sredna Gora Mountains, north-western Bulgaria

    NASA Astrophysics Data System (ADS)

    Dochev, Docho

    2015-03-01

    The inoceramid bivalves of the genus Mytiloides, from the Turonian (Upper Cretaceous) of the Sredna Gora Mts (north-western Bulgaria), are studied. The material comes from three sections: Izvor, Filipovtsi, and Vrabchov dol. Eight species are described taxonomically, with one left in open nomenclature: M. cf. mytiloides (Mantell, 1822), M. mytiloidiformis (Tröger, 1967), M. incertus (Jimbo, 1894), M. scupini (Heinz, 1930), M. herbichi (Atabekian, 1969), M. striatoconcentricus (Gümbel, 1868), M. labiatoidiformis (Tröger, 1967) and M. carpathicus (Simionescu, 1899). Mytiloides incertus and Mytiloides scupini are index species for the eponymous Upper Turonian inoceramid biozones.

  19. An abelisaurid (Dinosauria: Theropoda) tooth from the Lower Cretaceous Chicla formation of Libya

    NASA Astrophysics Data System (ADS)

    Smith, Joshua B.; Dalla Vecchia, Fabio M.

    2006-10-01

    An isolated theropod dinosaur tooth discovered in 1984 near Nalut in northwestern Libya is the only known dinosaur record from the Aptian-Albian (Lower Cretaceous) Chicla Formation in the Jabal Nafusah region of the country. The tooth was re-examined in an effort to better ascertain its taxonomic affinities. A stepwise discriminant function analysis compared the Libyan tooth to the dentitions of 24 other theropods and classified the tooth with cranial material from the Late Cretaceous of India previously referred to the abelisaurid Indosuchus. The temporal and paleogeographic "distance" separating the Libyan specimen from " Indosuchus" indicates that the former cannot pertain to that genus. However, the results of the analysis and synapomorphies of Abelisauridae present on the Libyan crown indicate that it can be referred to the clade, thus contributing to the growing record of Abelisauridae in the Cretaceous of mainland Africa.

  20. 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.

  1. Formation of the soft-sediment deformation structures and its constraints on dinosaur fossil burial of the Cretaceous in Zhucheng, Shandong province, East China

    NASA Astrophysics Data System (ADS)

    He, Bizhu; Qiao, Xiufu; Cai, Zhihui; Tian, Hongshui; Chen, Shuqing

    2013-04-01

    The triangular-shaped Zhucheng depression is located in the southwestern part of the Jiaolai basin, Jiaodong peninsula, East China. Various soft-sediment deformation structures are recognized in the southern Zhucheng depression, which have behaviour are plastic and/or brittle. Soft-sediment deformation structures mainly include undulate fold, mound and sag, diapir, convolute deformation and seismic-unconformity in the Lower Cretaceous, which are composed of fine-grained sediments in lacustrine environment, while load structure, ball and pillow structure, plunged sediment mixtures structure, fault-graded occurred in the Upper Cretaceous, which formed in a conglomeratic or coarse arenaceous alluvial fan and flood-plain setting. These soft-sediment deformation structures are proposed triggered by paleoearthquake. The deformed layers and undeformed layers developed in intervals, suggesting frequent seismic activities. In studied area, numerous giant hadrosaurid skeleton fossils have been found in the Upper Cretaceous Wangshi Group science 1958, and unusual and abundant dinosaur track fossils have been discovered in the Lower Cretaceous Yangzhuang Formation of Laiyang Group. The widespread identified soft-sediment deformation structures are proximately underlying or overlying these dinosaur fossil bearing strata. The depositional setting changed while multiple paleo-seismic events and tectonic activity happened. In the Early Cretaceous, after the occurrence of paleo-earthquakes and environmental changes, dinosaurs migrated and a lot of tracks with similar orientation on lacustrine offshore were preserved. In the Late Cretaceous, a large-scale dinosaur fossil layers and paleo-earthquake records occurred in intervals, indicating that the dinosaur fossils may be associated with large-scale debris flow and frequent earthquake events. Based on regional tectonic setting, distribution of soft-sediment deformation structures and predicted magnitude of paleo-earthquakes, the

  2. 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.

  3. 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.

  4. Architecture of Upper Cretaceous rhyodacitic hyaloclastite at the polymetallic Madneuli deposit, Lesser Caucasus, Georgia

    NASA Astrophysics Data System (ADS)

    Popkhadze, Nino; Moritz, Robert; Gugushvili, Vladimer

    2014-09-01

    This study focuses on a well-exposed section of the Artvin-Bolnisi zone located in the open pit of the Madneuli ore deposit, Lesser Caucasus, Georgia. Detailed field and petrographic observations of the main volcano-sedimentary lithofacies of its Upper Cretaceous stratigraphic succession were carried out. Whole rock geochemistry studies support the interpretation of intense silicification of the rocks, and supports our petrographic studies of samples from the Madneuli open pit, including lobe-hyaloclastite described in detail during this study. A particular focus concerned lobe-hyaloclastite exposures in the Madneuli open pit, singled out for first time in this area of the Lesser Caucasus. Two types of hyaloclastite are recognized at the Madneuli deposit: hyaloclastite with pillow-like forms and hyaloclastite with glass-like selvages. The petrographic description shows a different nature for both: hyaloclastite with glass-like selvages represented by devitrification of volcanic glass, which is replaced by quartz and K-feldspar overgrowth of crystals in the groundmass and elongated K-feldspar porphyry phenocrysts. Perlitic cracks were identified during thin section observation. The Hyaloclastite with pillow-like forms consists of relicts of volcanic glass and large pumice clasts replaced by sericite. Key observations are presented in the case of lobe-hyaloclastite and their immediate host volcano-sedimentary environment to constrain their depositional setting. A paleoreconstruction of their environment is proposed, in which hyaloclastite record the interaction of magma emplaced in unconsolidated volcano-sedimentary rocks associated with a submarine rhyodacite dome, emplaced during several magmatic pulses. Our study shows that the predominant part of the host rock sequence of the Madneuli polymetallic deposit was deposited under submarine conditions, which is in agreement with volcanogenic massive sulfide models or transitional, shallow submarine magmatic to

  5. 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

  6. 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

  7. Marine magnetic anomaly 33 34 identified in the Upper Cretaceous of the Great Valley Sequence of California

    NASA Astrophysics Data System (ADS)

    Ward, Peter D.; Verosub, Kenneth L.; Haggart, James W.

    1983-02-01

    An interval of reversed magnetic polarity has been located in Upper Cretaceous rocks of the Great Valley Sequence of California. The interval has been found at four sites, two on each side of the Sacramento Valley. In each case, the reversed interval is associated with the same ammonite local range zone. Firm biostratigraphic correlation and the structure of the magnetic polarity time scale allow us to determine that the reversed interval corresponds to marine magnetic anomaly 33 34 and represents the lower part of the Campanian Stage. The reversed interval serves as a marker horizon linking the different faunal assemblages and sedimentary facies of the Great Valley Sequence. It also provides the first direct correlation of provincial biostratigraphic zones of the North Pacific province with the Cretaceous stages in Europe.

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. The Upper Cretaceous Gosau Basins Of The Apuseni Mts./Romania; Basin Analysis, Provenance Analysis And Thermal History

    NASA Astrophysics Data System (ADS)

    Schuller, V.; Frisch, W.

    2003-12-01

    The remnants of the Upper Cretaceous Gosau basins of the Apuseni Mts. record a similar sedimentary succession as the Gosau basins of the Eastern Alps: the Lower Gosau subgroup, represented by shallow marine sediments, and the Upper Gosau subgroup (turbiditic flysch and pelagic sediments). The controlling tectonic process of the Austroalpine Gosau basins is proposed to be subduction tectonic erosion, which led to the strong subsidence within these basins. Investigations on heavy minerals and the maturation of organic matter can help to understand the sudden subsidence which took place in Campanian/Maastrichtian time. The Lower Gosau subgroup reflects a predominantly metamorphic clastic source. In the Upper Gosau subgroup the metamorphic influence becomes less important. In some samples Chrome Spinel and Glaucophane has been identified. Both minerals in one assemblage show that a former accretional wedge with high-pressure rocks and obducted oceanic crust was eroded. The vitrinite reflectance data show a range of 0,8 to 1,8 % Rr within the Upper Cretaceous sequence. Increased coalification was measured close to large Banatitic and Neogene intrusions (up to 5.0 % Rr). For basin modeling, an erosion of 1600 m of Late Cretaceous sediments has been computed. Together with the measured and interpreted field data, the entire Gosau succession had a max. thickness of 2800 m. This thickness values are also reported from the Eastern Alps. Fission track dating was used to determine the age of the dedritic Zirkons. With this age-population-method a dynamic evolution of the hinterland concerning its exhumation and erosion can be modeled. Combined with models based on Apatit fission track length, a rapid uplift of the crystalline basement can be shown. All these results prove the similarity to the Gosau Basins of the Eastern Alps and the assumption that a direct connection to the Basins in the Apuseni Mts. existed during the Upper Cretaceous time. The main mechanism for the

  13. 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.

  14. 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

  15. Depositional systems and oil and gas plays in the Cretaceous Olmos Formation, South Texas

    SciTech Connect

    Tyler, N.; Ambrose, W.A.

    1986-01-01

    This study covers an eight-county area and includes almost the entire subsurface extent of the formation from outcrop in Maverick County to the Cretaceous shelf edge in Webb and La Salle Counties. The authors trace the development and depositional environments of the Catarina and Big Foot delta systems and the Rocky Creek barrier/strandplain system and discuss the seven oil and gas plays in the Olmos formation, including active downdip oil, gas, and condensate-rich plays along the Lower Cretaceous shelf edge in La Salle and McMullen Counties. Recent developments in Olmos trends suggest that the best years of production may lie ahead. Youthful shelf-edge gas, condensate, and oil plays are highly productive and, together with wildcat prospects further basinward, offer the best potential for continued high-level production from this mature province.

  16. 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.

  17. 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.

  18. Depositional environments and fluvial system changes in the dinosaur-bearing Sânpetru Formation (Late Cretaceous, Romania): Post-orogenic sedimentation in an active extensional basin

    NASA Astrophysics Data System (ADS)

    Therrien, François

    2006-12-01

    The Sânpetru Formation (Haţeg Basin, Romania) was deposited in an active extensional basin in response to the post-orogenic collapse of the Southern Carpathians. Despite being one of the best exposed latest Cretaceous continental successions of Eastern Europe and having great potential to improve knowledge about the Mesozoic evolution of the Carpathian orogen and the latest Cretaceous terrestrial paleoenvironments of Europe, this formation has been the subject of limited sedimentologic research. Fourteen stratigraphic sections were measured in the Sânpetru Formation throughout an 860-m-thick interval exposed along the Sibişel Valley in order to conduct the most detailed stratigraphic and sedimentologic study of this formation to date. The Sânpetru Formation is a repetitive succession of fining-upward units composed of stratified and structureless sandstones, conglomerates, and mudstones. Facies analysis reveals that the Sânpetru Formation was deposited by braided streams that flowed through a symmetrical, extensional basin. The low variability of paleocurrent direction, the sheet-like architecture of the deposits, and the paucity of channel-shaped scours indicate poorly channelized flow across a shallow, broad braidplain. Small-scale fluctuations in sandstone/mudstone ratio and maximum grain size of channel deposits in the lower Sânpetru Formation reflect autocyclic shifts in paleochannel position. In the upper Sânpetru Formation, sandstone/mudstone ratios and maximum grain size of channel deposits increase, paleocurrent direction changes significantly, and hydromorphic paleosols become the sole type of paleosols present. These changes reflect an episode of rapid uplift of the source area and the basinward creation of accommodation space below the local water table, which resulted in the creation of extensive wetlands. The wetlands of the upper Sânpetru Formation were not an environment favorable for the formation of dinosaur bonebeds, which are found in

  19. 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

  20. 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

  1. A revised inoceramid biozonation for the Upper Cretaceous based on high-resolution carbon isotope stratigraphy in northwestern Hokkaido, Japan

    NASA Astrophysics Data System (ADS)

    Hayakawa, Tatsuya; Hirano, Hiromichi

    2013-06-01

    Hayakawa, T., Hirano, H. 2013. A revised inoceramid biozonation for the Upper Cretaceous based on high-resolution carbon isotope stratigraphy in northwestern Hokkaido, Japan. Acta Geologica Polonica, 63 (2), 239-263. Warszawa. Biostratigraphic correlations of inoceramid bivalves between the North Pacific and Euramerican provinces have been difficult because the inoceramid biostratigraphy of the Japanese strata has been based on endemic species of the northwest Pacific. In this study, carbon stable isotope fluctuations of terrestrial organic matter are assembled for the Upper Cretaceous Yezo Group in the Haboro and Obira areas, Hokkaido, Japan, in order to revise the chronology of the inoceramid biozonation in Japan. The carbon isotope curves are correlated with those of marine carbonates in English and German sections with the aid of age-diagnostic taxa. According to the correlations of the carbon isotope curves, 11 isotope events are recognised in the sections studied. As a result of these correlations, the chronology of the inoceramid biozones of the Northwest Pacific has been considerably revised. The revised inoceramid biozones suggest that the timing of the origination and extinction of the inoceramids in the North Pacific biotic province is different from the stage/substage boundaries defined by inoceramids, as used in Europe and North America.

  2. "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

  3. 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

  4. 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.

  5. Paleomagnetic study of the Cretaceous Morelos Formation, Guerrero State, southern Mexico

    NASA Astrophysics Data System (ADS)

    Urrutia-fucugauchi, J.

    1988-03-01

    Paleomagnetic results are reported for a ~ 30 m thick limestone section of the Albian-Cenomanian Morelos Formation, Guerrero State, in southern Mexico (-17.75 °N, 99.50° W). Seventy-two specimens from 35 samples were subjected to detailed alternating field (AF) or thermal demagnetizations. Most specimens were stable and presented a single magnetization component remaining after removal of low-coercivity, low-blocking temperature components. End-point and vector analyses give a mean direction and pole position after structural correction (dip ~ 14°) of D = 332.7°, I = 46.8°, k = 215, α95 = 4° and 63° N, 198° E ( dp = 3, dm = 5), respectively. The pole position agrees with mid-Cretaceous poles reported for cratonic North America, suggesting that the area was already keeping a similar latitudinal position relative to the North American craton by mid-Cretaceous time. Most samples present normal polarity, as expected within the Cretaceous normal interval, but four samples from a single bed present intermediate and reverse polarity, suggesting the occurrence of a reverse event during the late Albian-earliest Cenomanian.

  6. 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

  7. 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].

  8. 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

  9. New oil exploration play in Florida: The upper Fredericksberg Dollar Bay Formation

    SciTech Connect

    Mitchell-Tapping, H.J. )

    1990-09-01

    The Fredericksberg of South Florida may have a great oil potential that has been overlooked as a primary target in past decades. Previous exploration in the area has targeted the Lower Cretaceous oil-producing Sunniland Formation lower in the stratigraphic section. The Fredericksberg Dollar Bay Formation has hydrocarbon shows in many wells occurring in limestone biohermal deposits as well as in an upper dolomitic section. The Dollar Bay Formation is part of the Big Cypress Group of the Comanchean Series of the Lower Cretaceous. The Lower Cretaceous lithology is composed of evaporitic-carbonate cycles consisting of anhydrites, dolomites, and limestones. There are also present some calcareous shales, mudstones, salt, lignitic material, and carbonaceous material, especially in the anhydrite and limestone intervals. The limestones are usually micritic, chalky, calcarenitic, sometimes argillaceous, containing skeletal particles of gastropods, pelecypods, ostracods, algae, and forams together with ooids, oncolites, grapestones, and fecal pellets. The color of the limestone ranges from white to gray to tan to dark brown. The anhydrite is usually nodular, microcrystalline, or crystalline and is usually bedded. The dolomite crystals range from euhedral to sucrosic and occur in about 30% of the formation. The expected production in the Dollar Bay Formation will be from a leached calcarenite or a dolomite. Petrological examination of core and cuttings samples show a trapping mechanism and reservoir quality and content similar to the oil pay-zone of the Sunniland Formation in Felda field. In the wells examined the reservoir porosities range from 13.6% to 28.7% with permeabilities ranging from 4.9 md to 119.0 md in a dolomite section, while in the limestone the porosities range from 9.2% to 32.7% with permeabilities from 5.2 md to 59.0 md. More than 20 wells have been evaluated for lithology, porosity, diagenesis, cementation, and the direction of hydrocarbon migration.

  10. Occurrence of Upper Cretaceous pelagic carbonates within ophiolite-related pillow basalts in the Mt. Kozara area of the Vardar zone western belt, northern Bosnia

    NASA Astrophysics Data System (ADS)

    Grubić, Aleksandar; Radoičić, Rajka; Knežević, Mirjana; Cvijić, Ranko

    2009-03-01

    Deformed lenses of red silty micrite interstratified with basaltic pillow lavas outcrop at the confluence of the River Crna Reka and Krvavac Creek on Mt. Kozara in northern Bosnia. Interbedded pelagic carbonates contain microfossils, notably several species of Globotruncana, of Upper Santonian-Lower Campanian age. The pillow lavas and sediments form part of ~ 50 km 2 tectonically emplaced body of mafic igneous rocks, composed of pillow lava, sheeted diabase and minor gabbro. This body is tectonically emplaced within melange of the Vardar zone western belt. The basic igneous body has been interpreted as the upper part of an ophiolite that was tectonically emplaced when Neotethys finally closed during latest Cretaceous time. Accordingly, the Late Cretaceous age of the interbedded pelagic sediments, as reported here, indicates that oceanic crust still existed in this region of the Tethyan orogen during Late Cretaceous time.

  11. 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

  12. 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

  13. 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.

  14. 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.

  15. 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

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Petrochemistry and tectonic significance of Lower Cretaceous Barros Arana Formation basalts, southernmost Chilean Andes

    NASA Astrophysics Data System (ADS)

    Stern, C. R.; Mohseni, P. P.; Fuenzalida, P. R.

    The Lower Cretaceous Barros Arana Formation (Albian, hornblende KAr age of 104 Ma), in the Magallanes region of Chile, consists of a sequence of spilitized clinopyroxene- and amphibole-bearing mafic dikes and lavas, and volcaniclastic breccias, occurring within the sedimentary infill of the Rocas Verdes marginal basin and its eastward extension onto the Cretaceous continental platform. Although the original alkali and alkaline earth element concentrations of the basaltic lavas and dikes have been altered by spilitization, the presence of relict pargasitic amphibole phenocrysts, the absence of orthopyroxene, and high LREE contents and LREE/HREE ratios imply mildly alkaline affinities for these basalts. Their low TiO 2 and HFSE (Zr, Nb, Ta, and Hf) contents and high LREE/HFSE ratios suggest affinities with convergent plate boundary arc magmas. The Barros Arana basalts are interpreted as mafic members of the mildly alkaline shoshonitic rock suite of subduction-related arcs. They may have formed as subduction geometry began to undergo the changes (flattening) that ultimately led to the initiation of the closure, deformation, and uplift of the Rocas Verdes basin by the late or post-Albian. The low initial 87Sr/ 86Sr (0.7031) and high initial 143Nd/ 144Nd (0.51277) of the basalts indicate that a generally extensional tectonic regime east of the main calc-alkaline arc allowed eruption of these mafic shoshonites without interaction with continental crust (in contrast to the contemporaneous plutons of the Patagonian batholith).

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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

  8. 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., Jr.; 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.

  9. 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.

  10. 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

  11. 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

    U.S. Geological Survey Western Gulf Province Assessment Team

    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).

  12. Isolated dinosaur teeth from the Lower Cretaceous Shahai and Fuxin formations of northeastern China

    NASA Astrophysics Data System (ADS)

    Amiot, Romain; Kusuhashi, Nao; Xu, Xing; Wang, Yuanqing

    2010-10-01

    Isolated dinosaur teeth recovered from seven localities near Fuxin (western Liaoning Province, northeastern China) are described. They come from sediments belonging to the Shahai and Fuxin formations, considered to be Aptian to Albian in age. Seven taxa have been recognized. They include the oviraptorosaur Incisivosaurus, dromaeosaurid theropods, Euhelopus-like sauropods, as well as indeterminate nodosaurid, ankylosaurid, iguanodontoid and basal neoceratopsian ornithischians. The Shahai and Fuxin dinosaur faunas show the persistence of some Jehol biota taxa such as the highly specialised Incisivosaurus, basal titanosauriform sauropods, basal neoceratopsians and some dromaeosaurids, and the addition of more derived iguanodontoids and ankylosaurians. The persistence of some dinosaurs of the Jehol Biota into the Shahai and Fuxin formations suggests a long term stability of Liaoning terrestrial environments during the Early Cretaceous. Despite sampling bias and the rather small sample that must be taken into account, teeth abundances show a significant compositional difference between the localities of the Shahai and Fuxin formations, neoceratopsian teeth representing one third of dinosaur tooth remains in the Shahai Formation whereas they are totally absent in the Fuxin Formation. Ankylosaur teeth, in contrast, represent 3% of total remains in the Shahai Formation, whereas they seem to be the only herbivorous dinosaurs in the Fuxin Formation with 40% of the total number of teeth (the rest being theropod dinosaur teeth). Although a difference in micro-environmental conditions between Shahai and Fuxin localities may at least partly explain such pattern, the unusual and unbalanced faunal composition of Fuxin localities remains enigmatic and will need further field collecting in order to be clarified.

  13. Estimation of aquifer hydraulic parameters from surface geophysical measurements: a case study of the Upper Cretaceous aquifer, central Sinai, Egypt

    NASA Astrophysics Data System (ADS)

    Massoud, Usama; Santos, Fernando; Khalil, Mohamed A.; Taha, Ayman; Abbas, Abbas M.

    2010-05-01

    The integration of geophysical data with direct hydrogeological measurements can provide a minimally invasive approach to characterize the subsurface at a variety of resolutions and over many spatial scales. The field of hydrogeophysics has attracted much attention during the last two decades. In this domain, the geophysical data inverted to geophysical models are interpreted in terms of the hydrogeology to serve as a basis for the definition of hydraulic models in the areas of interest. The hydraulic conductivity ( K) value measured in a reference borehole has been combined with the electrical conductivity obtained from nearby geo-electromagnetic sounding data in the Cenomanian (Upper Cretaceous) aquifer, central Sinai, Egypt. The resulting relation was interpreted with Dar Zarrouk parameters to infer the transmissivity variations at other vertical electrical sounding locations, where K values are unknown. Coincident transient electromagnetic data have been adopted to increase accuracy while interpreting the aquifer geoelectrical properties. The results indicate that the transmissivity values in the aquifer of interest vary from 2,446 to 9,694 m2/day, and K varies from 12.9 to 57.0 m/day throughout the studied area.

  14. Geological and geochemical evidence for vertical migration of Upper Cretaceous sourced oils into tertiary reservoirs: Winn and Grant Parishes, Louisiana

    SciTech Connect

    Echols, J.B.; Zimmerman, R.K.; Goddard, D.G.

    1995-10-01

    Analyses of three Wilcox oils taken from the Colgrade Field (Carrizo sand reservoir), Bulger Creek Field (middle Wilcox sand reservoir), both in Winn Parish, and the Blue Lick Field (middle Wilcox sand reservoir) Grant Parish, Louisiana, correlate with other Gulf Coast oils sourced from the Upper Cretaceous (probably Eagle Ford or Tuscaloosa). All three samples are mature and highly biodegraded. The oils from Blue Lick and Bulger Fields contain bisnorhopane (BNH), a Wilcox and younger biomarker in central Louisiana and southwest Mississippi. BNH was identified previously by the authors in chalk oil from Clark Creek Field, Wilkinson Co., Mississippi. Previous studies project northeast-southwest wrench faulting (Boeuf River Fault) into the oil sample area. This faulting, and associated extensional fracture/fault and salt tectonism cause the conduits for vertical migration which emplaced the sampled oils into Wilcox reservoirs. The oils probably migrated from both the Eagle Ford/Tuscaloosa source beds and from fractured Austin chalk reservoirs breached by faulting. The oils provide additional evidence that Wilcox and younger oil reservoirs of central Louisiana and southwest Mississippi were filled by vertical migration from Mesozoic source beds in contrast to long range lateral migration proposed by earlier workers. The Central Louisiana Fracture Zone is described as an extensional fracture zone generated by wrench faulting. The trend of the zone coincides closely with that of the LaSalle Arch and is important in concentrating hydrocarbons along the arch. Exploration targets arise in all traps above Eagle Ford/Tuscaloosa source beds in the area.

  15. 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.

  16. 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)

  17. 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

  18. 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

  19. The Earliest Fleshy Cone of Ephedra from the Early Cretaceous Yixian Formation of Northeast China

    PubMed Central

    Yang, Yong; Wang, Qi

    2013-01-01

    Bracts of female cones of extant gymnosperm Ephedra (Joint fir) are either colorful and fleshy (section Ephedra), or dry-winged and membranous (section Alatae), or dry and coriaceous (section Asarca), which have played a crucial role in long-distance seed dispersal that is responsible for a wide distribution of the genus in semiarid and arid areas of Eurasia, North Africa, North America, and South America. Recent molecular systematic studies on Ephedra have suggested that the fleshy bracts in character evolution may be plesiomorphic relative to the dry, membranous and coriaceous bracts. However, little is known about when the fleshy bracts of Ephedra have made their debut in the geological past. Herein, we describe a novel, fleshy bract-bearing female cone macrofossil from the Early Cretaceous (ca. 120—125 Ma) Yixian Formation in Liaoning, northeastern China. This cone bears three ellipsoid seeds subtended by only one whorl of fleshy bracts. Each seed has a thin outer envelope and an inner integument that extends upward and passes through the opening of the outer envelope, forming a thin and straight micropylar tube. Such a syndrome shows the closest similarity to an extant triovulate species Ephedra intermedia in the section Ephedra, but the latter bears a whorl of terminal fertile bracts and more than one whorl of inferior sterile bracts, and a thick outer envelope. Hence, we establish a new fossil species Ephedra carnosa. Our discovery provides the first direct macrofossil evidence for the previous molecular systematics of Ephedra, implying that the origin of fleshy bracts in Ephedra should not have been later than that of the membranous and coriaceous bracts by at least the Early Cretaceous. PMID:23341964

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. 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

  5. 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

  6. Lakota Formation, southern Black Hills, South Dakota: an Early Cretaceous evolving fluvial system

    SciTech Connect

    Dahlstrom D.J.; Fox, J.E.

    1986-08-01

    The fluvial, Early Cretaceous Lakota Formation consists of four spatially and temporally distinct sandstone units in the southern Black Hills and southeastern Powder River basin. Three of these units crop out in proximity to an area of uranium roll-front development (Edgemont mining district) where approximately 2300 wells were drilled and logged. Comparison of the resistivity logs of several of these wells with continuous cores of the Lakota Formation confirms their lithologic sensitivity. These logs (utilized to assist in subsurface facies interpretations where cores were not available), cores, and outcrops are the basis for the following facies interpretations. The discharge, sediment load, and resulting sinuosity of this fluvial system varied substantially throughout the time of Lakota deposition. The oldest unit consists of tabular deposits with complex internal architecture comprised of cross-cutting lateral accretion deposits. Upward-fining grain size, upward-decreasing scale of sedimentary structures, and the angular relationship between lateral accretion surfaces and overlying crevasse-splay deposits support this conclusion. The intermediate unit of ephemeral stream sediments is characterized by abundant pebble- and cobble-strewn erosional surfaces with up to 1.5 m relief, very poor clast sorting, and trough and planar cross-bedding with concave-upward foresets. The youngest unit has a predominance of tabular cross-bedding with back flow climbing ripples and low dispersion of paleocurrent directions, suggesting a relatively straight, bed-load-type channel dominated by trains of sand waves.

  7. 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.

  8. 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. PMID:23874409

  9. 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

  10. 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

  11. Paleomagnetism of Upper Jurassic to Lower Cretaceous Volcanic and Sedimentary Rocks From the Western Tarim Basin: Implications for Inclination Shallowing and the ISEA? chron

    NASA Astrophysics Data System (ADS)

    Cogne, J.; Gilder, S.; Chen, Y.; Tan, X.; Courtillot, V.; Sun, D.; Li, Y.

    2002-12-01

    Stepwise demagnetization isolates a stable magnetic component in 13 sites of basalt flows and baked sediments dated at 113+-1.6 Ma from the Tuoyun section, western Xinjiang Province, China. Except for one flow from the base of the 300 m-thick section, the rest have exclusively reversed polarity. Five of 11 sites of Early Cretaceous red beds that underlie the basalts possess coherent directions that pass both fold and reversals tests. Six sites of Upper Jurassic red beds have a magnetic component that was likely acquired after folding in the Tertiary. The mean paleolatitude of the Lower Cretaceous red beds is 11° lower than that of the Lower Cretaceous basalts suggesting the red beds underestimate the true field inclination. We further test this result by calculating the paleolatitudes to a common point of the available Early Cretaceous to Present paleomagnetic poles from red beds and volcanic rocks from central Asian localities north of the Tibetan plateau. We find that paleolatitudes of volcanic rocks roughly equal the paleolatitudes calculated from the reference Eurasian apparent polar wander path (APWP) and that paleolatitudes of red beds are generally 10° to 20° lower than the paleolatitudes of volcanic rocks and those predicted from the reference curve. Our study suggests that central Asian red beds poorly record the Earth's field inclination, which leads to lower than expected paleolatitudes. Good agreement in paleolatitudes from volcanic rocks and the Eurasian APWP argues against proposed canted and non-dipole field models.

  12. 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

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

    PubMed

    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. PMID:24441791

  14. 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.

  15. Biostratigraphic correlation chart of some Upper Cretaceous rocks from the Lost Soldier area, Wyoming to west of Craig, Colorado

    USGS Publications Warehouse

    Bader, J.W.; Gill, J.R.; Cobban, W.A.; Law, B.E.

    1983-01-01

    This chart depicts the time-stratigraphic relations of some Upper Cretaceous rocks along the eastern and southeastern margins of the Greater Green River Basin, south-central Wyoming and northwestern Colorado. The purpose of this report is to release a preferred set of correlations based upon marine mollusk biostratigraphy. The senior author, with the help of B. E. Law, has acquired, synthesized, compiled, and interpreted data from various sources. These include selected published documents (see "References Cited") and unpublished reports of fossil identifications by W. A. Cobban who examined collections made by the late J. R. Gill. Numerous measured sections of Gill's were also utilized. It must be emphasized that all interpretations on this chart are based on information obtained from these sources and the senior author has yet to substantiate these correlations in the field. Not all data from the area of this study is included herein because it is either repetitive in nature or its reliability is uncertain. This uncertainty is due to the ambiguity inherent in both fossil identification and stratigraphic interpretation. Questionable unpublished material has been omitted while published data which is inconsistent with the senior author's correlations may be found in the footnotes portion of this report. The rock units are assigned to a range of ammonites that have been related to an absolute time scale. The ammonite zonation and age boundaries are adapted from Obradovich and Cobban (1975). "D" numbers are provided for each geographic locality where fossils were collected and described by personnel of the U.S. Geological Survey. These fossils may be accessed at the offices of the Survey in Lakewood, Colorado.

  16. Late Cretaceous-Cenozoic history of the Lake Baikal depression and formation of its unique biodiversity

    NASA Astrophysics Data System (ADS)

    Mats, V. D.; Shcherbakov, D. Yu.; Efimova, I. M.

    2011-08-01

    Independent methods of geological and molecular-biological chronologies have made it possible to define generally corresponding stages in the geological and biological evolution of the environments and communities of Lake Baikal since the Late Cretaceous, i.e., during the last 70 myr. All the abiotic elements drastically changed during geological evolution, with destruction of existing and formation of new natural complexes. Nevertheless, some specific zones retained relicts of former settings. The resulting present-day natural complex includes elements of different ages and geneses. Similar to different natural zones of the present-day Earth, which are populated by different biocoenoses, stages in the development of abiotic elements are also characterized by different faunal and floral assemblages. Some taxa were replaced by others, and the resulting aqueous biota of Lake Baikal includes different-age and ecologically different elements. The oldest groups of Baikal organisms appeared approximately 70 Ma ago, although the largest proportion of the lake biota started forming 4-3 Ma ago in response to the most drastic changes in the abiotic elements of the environment. The youngest taxa appeared 1.8 to 0.15 Ma ago, i.e., during the period when superdeep lake environments and mountainous glaciations were developing. The chronological coincidence of main stages in development of abiotic and biotic elements of the nature indicates their relationships. Particular transformations of abiotic elements and the probable mechanism of their influence on the evolution of living communities are also considered.

  17. 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

  18. 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

  19. Impressions of dinosaur skin from the Cretaceous Haman Formation in Korea

    NASA Astrophysics Data System (ADS)

    Paik, In Sung; Kim, Hyun Joo; Huh, Min

    2010-09-01

    The occurrences and features of two specimens of fossil dinosaur skin from Cretaceous Haman Formation in South Korea, including a new type of skin texture (development of micropolygons within scales) are described here for the first time, and several types of sedimentological aberrations of inorganic origin that are similar in appearance to fossil skin and therefore have the potential to be misidentified as fossil skin. The features and origins of fossil dinosaur skin found in South Korea with those of a diverse range of geological aberration structures resembling fossil skin are also compared. It is interpreted that dry climate, the presence of torn skin, and episodic sheetflood on an alluvial plain were related with the preservation of the Haman skin fossils. The preservation condition of the Haman skin fossils suggests that sheetflood deposits on a floodplain to mudflat environment under dry climatic condition are potential candidates for dinosaur skins to be found. The results of this study not only provide additional information that is helpful in understanding dinosaur skin, but also are useful in discriminating between true fossil skin and enigmatic sedimentological aberration structures resembling skin.

  20. 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

  1. 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.

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. 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.

  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. Hydrogeochemical Characterization of Formation Waters in Cretaceous Rocks from Southeast Mexico

    NASA Astrophysics Data System (ADS)

    Mendez-Ortiz, B. A.; Carrillo-Chavez, A.; Tritlla, J.; Levresse, G.; Varela, M.; Clara, L.; Caballero, E.

    2007-05-01

    Formation waters were sampled from ten different producing wells in several Cretaceous oil fields in central and north Tabasco, southeast of Mexico. All of them were analyzed for mayor and trace ions, as well as for 18O and D isotopes. The salinity in the central oil fields (TSD in ppm) ranges from 221,972 ppm to 243,372 ppm. The salinities are very similar in different oil wells. These salinities are 1 to 14 times higher than the salinity found in another fields (15,299 to 16,557 ppm), and 1 to 5 times higher than other field. A northern oil field salinity is characterized also by an important heterogeneity of it salinity due to salt intrusion and interaction with non uniform structures. The major ions analysis (Na+, Ca2+, K+, Mg+, Cl+, SO42-, HCO3-) suggests water-rock interactions in all the oil fields. This is the case, particularly marked in the central fields, where the brines are enriched in Mg in a range from 10 to 274 ppm. This is due to brines/dolomites interaction, while in other oil field, the higher concentration of Mg was only of 1.17 ppm. The central oil fields present depletion on sulfate concentrations (<5.9 ppm). This could be due to precipitation of metal sulfide (thermal reduction) in the form of pyrite and marcasite. Halogens (Br, Cl) concentration indicates three different origins for the formation waters. Water from the central wells is plotted on the evaporated marine water evolution line. Water from the southern wells is located close to marine water in the halite dissolution zone, whereas water form the northern wells is plotted in the diluted waters zone. Cl and Br evolution in the central field samples shows two different groups, and clearly reveal mixing processes between marine water and highly evolved evaporated seawater. Whereas water from the northern wells is plotted in the mixing zone between seawater with low salinity water trapped in Tertiary sediments which can migrate until mixed with older formation waters. The D-O stable

  9. 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.

  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. 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

  12. 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

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. 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

  19. 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

  20. 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).

  1. 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.

  2. 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

  3. 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

  4. Short Polarity Albian Events in the Cretaceous Normal Superchron - Magnetostratigraphy of the Morelos and Tlayua Formations (Mexico)

    NASA Astrophysics Data System (ADS)

    Benammi, M.; Urrutia-Fucugauchi, J.

    2007-12-01

    Interest in the long period of normal polarity in the Cretaceous has continued to increase since the early study of Helsley and Steiner (1969), who suspected that it corresponded to vast stretches of relatively low amplitude behaviour in the sea-floor magnetic anomaly profiles known informally as the "Cretaceous quiet zone". Since these first studies, paleomagnetists have continued to explore what is now known as the Cretaceous Normal Superchron, an interval of prolonged normal polarity from 118 to 84 Ma. Paleomagnetic data from sediment cores from the DSDP Holes 369, 386, and 364, were interpreted as brief reverse intervals (Keating and Helsley, 1978, 1979). Relatively fewer studies have been reported for land-based sections of pelagic and platform limestones; reports include studies in northern and central Italy (Vandenberg et al., 1978; Tarduno et al., 1992; Tarduno, 1990; Cronin et al., 2001) and Mexico (Urrutia-Fucugauchi, 1988; Benammi et al., 2006). We present here new magnetostratigraphic data for limestone sequences in central and southern Mexico from the Cretaceous Morelos and Tlayua Formations, which record short intervals of reversed polarity during the K normal superchron. The Morelos Formation has been revisited in Guerrero, southern Mexico, where the sequence of platform limestones with almost horizontal thick beds is well-exposed. The magnetostratigraphy shows dominant normal polarity for the sampled sections, with the occurrence of three short reverse polarity intervals corresponding to the Albian, which have been re-sampled and studied in additional detail for magnetic mineralogy and remanent acquisition. The Tlayua Formation is sampled in Tepeji de Rodriguez area, which is known for its rich and well-preserved fossil contents. Age control has mainly been provided from studies on ammonites, belemnites and benthic foraminifera (Cantu, 1987; Seibertz and Buitron, 1987; Kashiyama et al., 2003). Nine polarity intervals are documented in the Tlayua

  5. Collapse of the Cretaceous Helvetiafjellet Formation due to tectonic activity at Kvalvågen, eastern Spitsbergen

    NASA Astrophysics Data System (ADS)

    Onderdonk, N.; Midtkandal, I.; Ahokas, J.

    2008-12-01

    A variety of features recording disturbance of Mid-Cretaceous sediments are exposed in coastal cliffs at Kvalvågen, east Spitsbergen. The most striking of these features are large displaced blocks of Helvetiafjellet Formation sandstone (ranging from 5 to 25 meters across) that were dropped down into underlying shale- dominated sediments along normal faults. In addition to the displaced blocks much of the sandstone unit is missing along a 2 km stretch of coastal exposure and must have been slipped out of the plane of exposure. Several hypotheses have been proposed to explain the style and cause of the Cretaceous collapse at Kvalvågen including delta front collapse (Nemec et al., 1988), landslides into a submarine canyon (Steel et al., 2001), and collapse related to magmatic activity (Midtkandal et al., 2007). New structural data and field observations show that the orientations and style of deformation are not entirely consistent with the previous hypotheses and are better explained as the direct result of tectonically produced topography (i.e., a fault scarp). The deformation at Kvalvågen is the result of west-side-down displacement along a north-striking fault that crops out at the southern end of the cliff exposure. Tectonic disturbance in the area began in Hauterivian time and was over by the early Aptian. These outcrops are the only evidence of tectonic activity in the area during the Mid-Cretaceous and may be the result of displacement along a previously unrecognized extension of the Lomfjorden fault zone or related to regional stresses imposed by extensive sill intrusions during the formation of the High Arctic Large Igneous Province.

  6. 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.

  7. The Role of Upper-crustal Thickening in Spatially-focusing Synorogenic Extension: A Case Study from the Late Cretaceous-Paleocene Nevadaplano

    NASA Astrophysics Data System (ADS)

    Long, S. P.; Thomson, S. N.; Reiners, P. W.; Di Fiori, R. V.

    2015-12-01

    Synorogenic extension is often interpreted as gravitational spreading of thickened crust or as a response to thrust belt dynamics; however, the processes that spatially-localize extension during orogenesis are not fully understood. Here, we examine additional factors that control the location of synorogenic extension by presenting a case study from the hinterland plateau of the Sevier orogenic belt (or 'Nevadaplano'). The Eureka culmination, a 20 km-wide, N-trending anticline with 4.5 km of structural relief, was constructed in the plateau interior in eastern Nevada in the Early Cretaceous. After its construction, the culmination underwent 40% extension, accommodated by two sets of N-striking normal faults, which exhumed rocks from depths of 6-8 km, and pre-date a late Eocene unconformity. Well-defined fault geometries, stratigraphic thicknesses, and preservation of erosion surfaces allowed estimation of the contributions of tectonic exhumation versus pre- and post-extensional erosional exhumation. Time-temperature paths determined from zircon and apatite (U-Th)/He and fission-track thermochronology collected from Paleozoic quartzite in the footwalls of two normal faults demonstrate rapid (10 °C/Myr) Late Cretaceous to Paleocene (75-60 Ma) cooling, which we interpret as tectonic exhumation during extension, and which was concurrent with late-stage shortening in the frontal Sevier thrust belt. This example illustrates that structural and topographic relief generated within zones of localized upper-crustal thickening can spatially-focus extension during orogenesis. This observation, when combined with Late Cretaceous exhumation in core complexes in northeast Nevada and northern Utah, which also developed within sites of localized crustal thickening, illustrates that gradients in gravitational potential energy, at different scales and crustal levels, played a primary role in controlling the location of late-stage, synorogenic extension within the Nevadaplano.

  8. 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. PMID:25901363

  9. 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.

  10. 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

  11. 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

  12. Relationships of Bexar shale, Hensel sandstone, and Hensel dolomite (basal upper Trinity, Comanchean Cretaceous) in south-central Texas

    SciTech Connect

    Amsbury, D.L.

    1984-04-01

    The Bexar Shale has been considered the offshore equivalent of the Cow Creek Limestone, the overlying Hensel sandstone, or of the disconformity between them in outcropping sections. Cores and outcrops in Comal, Kendall, and northern Bexar Counties preserve calcitic and dolomitic caliche in the top of the Cow Creek Limestone. Above the caliche is 8-16 m(25-50 ft) of laminated or bioturbated, dolomitic siltstone and silty dolomite (Hensel dolomite). Dolomite is euhedral and silt-sized. The lower part contains collophane grains and oyster shells replaced partly by chalcedony. Carbonate grains within the upper part include angular and well-rounded mollusk and echinoid fragments; many are pyritic and coated by glauconite. Terrigenous grains in Hensel dolomite grade upward from silt to coarse subarkose sand from central Texas. In southern Bexar County, about 35 m (115 ft) of silt-, clay-, and calcite-mudstone referable to the Bexar Shale sharply overlie shallow marine Cow Creek Limestone, and grade abruptly upward into about 7 m (23 ft) of Hensel dolomite. Dolomite is overlain by calcarenite of the Glen Rose Formation containing subarkose sand grains. Similar distinctive sand grains occur in well cuttings of basal Glen Rose beds northeastward through Travis County. The Bexar represents a flood of clay-sized sediment from a distant source, spread across the San Marcos arch during a rapid transgression. Slightly younger sand, silt, and local clay of the Hensel sandstone were eroded from central Texas by a few flash floods during a major period of caliche formation in the area.

  13. 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

  14. Origin distribution and alteration of organic matter and generation and migration of hydrocarbons in Austin Chalk, Upper Cretaceous, Southeastern Texas

    NASA Astrophysics Data System (ADS)

    Grabowski, G. J., Jr.

    1981-08-01

    The Austin Chalk is an impure onshore chalk that was deposited on a ramp marginal to the Gulf of Mexico during the Late Cretaceous. Basinal chalks are organic rich, commonly containing 0.5-5.0% amorphous, sapropelic kerogen derived from marine organic matter with only trace amounts of terrestial kerogen. Less organic matter was deposited and perserved in oxygenated shallow water, and fresh-water diagenesis oxidized the organic matter on outcrop. In each sample, the kerogen is concentrated in microstylolites, with organic fluids segregated in micropores in the chalk.

  15. 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.

  16. 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.).

  17. Lower Cretaceous bentonitic strata in southwestern Montana assigned to Vaughn Member of Mowry Shale (East) and of Blackleaf Formation (West)

    USGS Publications Warehouse

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

    1989-01-01

    The Vaughn Member, newly assigned to the Mowry Shale in this report, comprises strata that crop out in the Greenhorn, Gravelly, Madison, and Gallatin ranges, and the Centennial and Beartooth mountains of southwestern Montana. Herein the member is correlated with the Vaughn Member of the Blackleaf Formation, which crops out to the west in the Lima Peaks area, Snowcrest Range, and Pioneer Mountains. Strata assigned to the Vaughn Member of the Blackleaf Formation in southwestern Montana exhibit the same contrasting relationships that exist in northwestern Montana. The Vaughn Member of the Mowry is late Albian in age, determined by bracketing with shallow water marine bivalves in the Muddy Sandstone below and palynomorphs in Mowry strata above. Palynomorphs from the Vaughn Member itself are typically mid-Cretaceous, but do not permit a more exact determination of age. -from Authors

  18. 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

  19. Magnetic inclination shallowing problem and the issue of Eurasia's rigidity: insights following a palaeomagnetic study of upper Cretaceous basalts and redbeds from SE China

    NASA Astrophysics Data System (ADS)

    Li, Yong-Xiang; Shu, Liangshu; Wen, Bin; Yang, Zhenyu; Ali, Jason R.

    2013-09-01

    Redbeds are an important source of palaeomagnetic data, but they often record inclinations shallower than that of the ancient local geomagnetic field. Discrepancy of palaeopoles from Cretaceous redbeds in South China Block (SCB) and the coeval Eurasia reference pole is commonly attributed to inclination shallowing. However, redbed-derived palaeomagnetic data from the block have rarely been critically assessed with data from coeval volcanic rocks that should be unaffected by the problem. Here, we address the issue using high-quality palaeomagnetic data from Upper Cretaceous (˜95 Ma) amygdaloidal basalts and coeval redbeds from Jiangshan, Zhejiang Province and Guangfeng, Jiangxi Province. Stepwise thermal and alternating field demagnetizations isolated stable components that in the basalts are carried by a mixture of magnetite and titanomagntite and in the sedimentary units by haematite. The stable components are regarded as primary based on positive intraformational conglomerate tests and a regional tilt test. The redbeds yield a tilt corrected mean direction of D = 20.9°, I = 35.8°, α95 = 8.7°, N = 6, which is statistically indistinguishable from the mean direction of the basalts (D = 17.6°, I = 38.1°, α95 = 8.6°, N = 11), suggesting that the former do not suffer from the problem. In addition, analysis of the other Late Cretaceous SCB palaeopoles reveals two groups with one at relatively high (`H', ˜80°N) latitudes and the other at relatively low (`L', ˜70°N) latitudes. Importantly, each comprises palaeopoles from both redbeds and volcanic rocks, and reasonable consistency exists within each group, further attesting that SCB redbeds do not suffer significant inclination shallowing. Comparison of the SCB palaeopoles with a newly defined coeval reference pole for Europe indicates an ˜11° separation. Since inclination shallowing, over 1000 km tectonic shortening, and apparent polar wander appear unlikely, the ˜11° discrepancy may provide evidence for

  20. 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

  1. 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.

  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. 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

  4. 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.

  5. Assessment of fracture-induced anisotropy in the Austin Chalk Formation (Upper Cretaceous), central Texas

    SciTech Connect

    Edwards, D.A. )

    1990-05-01

    This study relates geophysical and geological data to the detection of fractures and their influence on the movement of fluid in the Atco Member of the Austin Chalk in central Texas. In areas of production, the Austin Chalk has very low matrix permeabilities, with hydrocarbons confined to zones of near-vertical, stress-aligned fractures. Horizontal drilling has been estimated to increase per well reserves in the Austin Chalk from 75,000 bbl and 82 mmcf to 500,000 bbl and 500 mmcf. The objective of deviated wells in the Austin Chalk is to intersect at right angles as many of the hydrocarbon-prone fracture zones as possible. Therefore, the detection and description of these fracture zones prior to drilling is critical. Fractures have been proven to influence the velocities of shear waves. To assess shear wave velocities in different directions, several shear wave refraction and three-component vertical seismic profiles have been acquired. These data provided a measure of the fracture-induced shear wave anisotropy and an indication of the dominant fracture trend. Other data, including azimuthal resistivity surveys, cores, and aerial photographs, provided additional control for evaluating the fractures. The final phase of the study compares the geophysical and geological interpretations to the result of shallow groundwater pumping tests. The pumping tests have been conducted in vertical boreholes and were designed to evaluate the influence of the fracturing on fluid movement.

  6. 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.

  7. MORB to supra-subduction geochemical transition in the extrusive sequences of major upper Cretaceous ophiolites of Iran

    NASA Astrophysics Data System (ADS)

    Babaie, H. A.; Khalatbari Jafari, M.; Moslempour, M. E.

    2014-12-01

    We discuss the geochemical patterns and tectonomagmatic setting of the extrusive sequences in the Khoy, Kermanshah, Fannuj, Nosratabad, Dehshir, south and north Fariman, and Sabzevar ophiolite massifs of Iran. These sequences include pillow lava, sheet flow, hyaloclastite, hyaloclastic breccia, and interbeds of chert and pelagic limestone with Late Cretaceous micro fauna. The Khoy, north Fariman, and Sabzevar massifs also include Late Cretaceous-Early Paleocene supra-ophiolitic volcanic and volcano-sedimentary rocks that formed in a trough near the extrusive sequence. The Khoy pillow lava displays T-MORB characteristics but no chemical contribution from the components released from the subducted slab. On the other hand, the diabase dikes that cut the Khoy extrusive sequence show signatures of subduction zone magmatism and contribution from the melt released through the partial melting of the subducted slab. While lava in the Harsin (Kermanshah) extrusive sequence in west Iran displays E-MORB and P-MORB characteristics, the pillows in the Fannuj, north Fariman, Dehshir, and Sabzevar extrusive sequences indicate the contribution of both fluids and melt from the subducted slab. The Nosratabad and south Fariman ophiolites also show evidence for either melt or fluids, respectively. Partial melting of the subducted slab sedimentary cover may have formed the acidic pillow lava and sheet flow in the Fannuj and Nosratabad extrusive sequence, respectively. Some pillows in the Nosratabad, Sabzevar, north Fariman, and to a lesser extent, Dehshir extrusive sequence display the OIB geochemical characteristics. Mantle plumes or asthenospheric flow that probably moved up through weak zones of the subducted slab may have affected the partial melting of the mantle wedge above the slab. The combined OIB and supra-subduction characteristics suggest the role of the roll-back of the subducted slab in the magmatism of the northeast Iranian ophiolites. The clear MORB-like geochemical

  8. 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

  9. 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. 

  10. 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.

  11. 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

  12. 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

  13. 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.

  14. 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

  15. 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

  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. 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

  18. The first Pan-Podocnemididae turtle egg from the Presidente Prudente Formation (Late Cretaceous, Bauru Group), Brazil.

    PubMed

    Marsola, Júlio C De A; Grellet-Tinner, Gerald; Montefeltro, Felipe C; Langer, Max C

    2014-01-01

    Pan-Podocnemididae turtles are ubiquitous in Late Cretaceous rocks of the Bauru Group in southeastern Brazil. This group of side-necked turtles is particularly abundant in a turtle-bearing site of the Presidente Prudente Formation known as Tartaruguito. Here, we describe the first turtle egg (LPRP-USP 0052) from the Tartaruguito site. LPRP-USP 0052 is nearly complete but misses a pole and measures 5,1 and 2,9-2,2 centimeters due to its flattened minor axis. The egg morphology and microstructure were analyzed by observations performed with CT, Optic Microscopy, Scanning Electronic Microscopy and Wave Dispersion Energy analyses. The eggshell ranges from 145 to160 micrometers thick. Considering the matching morphology of the new specimen and its provenance from the stratigraphic horizon that yielded only the podocnemidids Bauruemys and Roxochelys, it is most likely that LPRP-USP 0052 was produced by a podocnemidid turtle.  PMID:25544080

  19. 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

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. Palynostratigraphic Studies of the Lower Cretaceous Sediments, Alamein Formation, Bahrein-1 Well in the Northern Part of the Western Desert, Egypt

    NASA Astrophysics Data System (ADS)

    Lashin, Gamal M. A.

    Palynostratigraphic studies of the Lower Cretaceous sediments, Alamein Formation, Bahrein-1 well in the northern part of the Western Desert, Egypt, have been carried out from an evolutionary and geological viewpoint. The palynoflora principally consists of pteridophytes, gymnosperms and some rare angiosperm pollen. The microflora shows that the palaeoenvironments were favorable for different kinds of plants. The recovered microflora, therefore, indicates an Early Aptian age and can be extended to the Early Albian. The palynological data revealed that the North Western Desert (N.W.D.) of Egypt belongs to the North Gondwana phytogeoprovince in the Early Cretaceous.

  5. 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

  6. 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.

  7. 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

  8. Petrography and geochemistry of vein-filling calcites, balcones fault zone, upper cretaceous strata, north-central Texas

    SciTech Connect

    Dawson, W.C.; Szymczyk, H.M.; Reaser, D.F.

    1994-12-31

    The Austin Chalk and the underlying Eagle Ford Shale are transected 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 generally northeastward, and many are cemented by sparry calcite. Slickensides, preserved on outer surfaces of calcite cements, record fault movement. Early calcite cements are nonferroan, and later cements are ferroan calcite. Petrographic analyses indicate the occurrence of fir-tree zoning and fluorescent inclusions within calcite cements. Vein-filling cements have stable isotopic signatures {delta}{sup 18}O -5.7 to -9.8% PDB; {delta}{sup 13}C +1.6 to +2.7% PDB that are markedly depleted in {delta}{sup 18}O relative to the chalk matrix, inoceramid shells, and the estimated value for Cretaceous seawater. The depleted {delta}{sup 18}O signatures of the vein-filling calcites are suggestive of precipitation from warm basinal 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-seal 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.

  9. Biostratigraphy of the Cretaceous/Tertiary boundary in the Sirwan Valley (Sulaimani Region, Kurdistan, NE Iraq)

    NASA Astrophysics Data System (ADS)

    Sharbazheri, Khalid Mahmood; Ghafor, Imad Mahmood; Muhammed, Qahtan Ahmad

    2009-10-01

    The Cretaceous/Tertiary (K/T) boundary sequence, which crops out in the studied area is located within the High Folded Zone, in the Sirwan Valley, northeastern Iraq. These units mainly consist of flysch and flysch-type successions of thick clastic beds of Tanjero/Kolosh Formations. A detailed lithostratigraphic study is achieved on the outcropping uppermost part of the Upper Cretaceous successions (upper part of Tanjero Formation) and the lowermost part of the Kolosh Formation. On the basis of the identified planktonic foraminiferal assemblages, five biozones are recorded from the uppermost part of Tanjero Formation and four biozones from the lower part of the Kolosh Formation (Lower Paleocene) in the Sirwan section. The biostratigraphic correlations based on planktonic foraminiferal zonations showed a comparison between the biostratigraphic zones established in this study and other equivalents of the commonly used planktonic zonal scheme around the Cretaceous/Tertiary boundary in and outside Iraq.

  10. Paleomagnetism and U-Pb geochronology of the late Cretaceous Chisulryoung Volcanic Formation, Korea: tectonic evolution of the Korean Peninsula

    NASA Astrophysics Data System (ADS)

    Jeong, Doohee; Yu, Yongjae; Doh, Seong-Jae; Suk, Dongwoo; Kim, Jeongmin

    2015-05-01

    Late Cretaceous Chisulryoung Volcanic Formation (CVF) in southeastern Korea contains four ash-flow ignimbrite units (A1, A2, A3, and A4) and three intervening volcano-sedimentary layers (S1, S2, and S3). Reliable U-Pb ages obtained for zircons from the base and top of the CVF were 72.8 ± 1.7 Ma and 67.7 ± 2.1 Ma, respectively. Paleomagnetic analysis on pyroclastic units yielded mean magnetic directions and virtual geomagnetic poles (VGPs) as D/ I = 19.1°/49.2° ( α 95 = 4.2°, k = 76.5) and VGP = 73.1°N/232.1°E ( A 95 = 3.7°, N = 3) for A1, D/ I = 24.9°/52.9° ( α 95 = 5.9°, k = 61.7) and VGP = 69.4°N/217.3°E ( A 95 = 5.6°, N = 11) for A3, and D/ I = 10.9°/50.1° ( α 95 = 5.6°, k = 38.6) and VGP = 79.8°N/242.4°E ( A 95 = 5.0°, N = 18) for A4. Our best estimates of the paleopoles for A1, A3, and A4 are in remarkable agreement with the reference apparent polar wander path of China in late Cretaceous to early Paleogene, confirming that Korea has been rigidly attached to China (by implication to Eurasia) at least since the Cretaceous. The compiled paleomagnetic data of the Korean Peninsula suggest that the mode of clockwise rotations weakened since the mid-Jurassic. Such interesting variation of vertical rotations in the Korean Peninsula might result from the strike-slip motions of major faults developed in East Asia (the Tancheng-Lujiang fault to the northwest and the Korea-Taiwan strait fault to the southeast), near-field tectonic forcing of the subducting Pacific Plate beneath the Eurasian Plate, and far-field expressions of the India-Asia collision.

  11. 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.

  12. 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).

  13. 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

  14. 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.

  15. 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.

  16. 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.

  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. Fracturing in upper Cretaceous Selma group Chalky marls, inner coastal plain of Alabama: stratigraphic (facies) control of joint development and regional joint-strike orientations

    SciTech Connect

    Bittner, E.; King, D.T. Jr.; Holston, I.

    1988-09-01

    In the inner coastal plain of Alabama, chalky marl is a distinctive sedimentary facies that contains more original biogenic calcareous-nannofossil components than the adjacent marls. The chalky marl is one facies in the cyclically arranged genetic packages that comprise the Mooreville and Demopolis Chalks of the lower part of the Upper Cretaceous Selma Group. Analysis of genetic-package stratigraphy shows that the chalky marls were deposited during relative sea level highstands. The chalky marls are selectively cemented by calcium carbonate, thus making a relatively well-indurated brittle rock. The chalky marls, in three sections over 15 m thick, host most of the systematic joints in the Mooreville and Demopolis. As a result, fracture-density mapping clearly delineates the outcrop belts of the thick fracture-prone chalky marls. Joint systems in the marls and chalky marls have two main strike trends (N30/degrees/E to N70/degrees/E and N20/degrees/W to N50/degrees/W) and two secondary strike trends (north to N10/degrees/E and east-west), which are nearly parallel and perpendicular, respectively, to crystalline bedrock structural trends and fracture zones. Thus, bedrock structural trends and fracture patterns appear to have propagated through the overlying Mesozoic rocks, dictating the orientation of joints in the chalky marls.

  19. 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.

  20. Deltaic deposits of the Upper Cretaceous Dad Sandstone Member of the Lewis Shale, south-central Wyoming

    SciTech Connect

    Perman, R.C.

    1987-01-01

    The Dad Sandstone Member is a prograding unit of sandstone and minor mudstone that separates upper and lower shale members of the Lewis Shale. Outcrops of this Maestrichtian-age unit have been examined in south-central Wyoming along the eastern margin of the Great Divide basin north of Rawlins, and in the Hanna basin to the east. These outcrops form two groups with very different characteristics, including thickness of sandstone and interbedded mudstone units, sedimentary structures, and fossils. In the western part of the area studied, the Dad Sandstone is interpreted to represent progradation in the lower delta-front region of the Sheridan delta that existed to the northwest. In the eastern portion of the study area the Dad Sandstone probably represents upper shoreface facies of interdistributary barrier bars. These deposits may be related to either the Sheridan delta to the north, or a north-trending uplift to the south. The Dad Sandstone in the eastern part of the study area is probably slightly younger than in the western part of the study area.

  1. 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.

  2. Inverted Regional Metamorphism in the Coaxially Refolded Tonga Formation: Evidence for Cretaceous Accretional Tectonics in the Cascades Crystalline Core

    NASA Astrophysics Data System (ADS)

    Jensen, L. A.; Lebit, H. D.; Paterson, S. R.; Miller, R. B.; Vernon, R. H.

    2008-12-01

    The Tonga Formation, on the westernmost boundary of the Cascades crystalline core, records Cretaceous plutonism, contact to regional metamorphism, and multiple episodes of folding related to intense east-west contractional deformation. The Tonga Formation is exposed in a fault-bounded, north-south elongate tectonic domain that comprises pelite-psammite metasediments, which increase from greenschist to amphibolite grade (south to north). This metamorphic gradient is inverted relative to a major westward verging and downward facing fold system that dominates the internal architecture of the formation. Sedimentary structures are remarkably well-preserved in the Tonga Formation, which allowed for the determination of younging directions. Using these and bedding-cleavage relationships, detailed field mapping indicates a stratigraphically overturned section that forms a large-scale antiformal syncline (exposed in the northern and eastern domain) and related synformal anticline (southern and western domain). The overturned nature of the strata and the geometry of gently north-plunging folds imply upsection a pre-existing tight, recumbent anticline refolded into a co-axial (type III) fold interference pattern. The core of this early anticline, exposed in the northern domain, corresponds with the higher metamorphic conditions of the inverted metamorphic gradient and early Cascades regional metamorphism ('M1') rarely decipherable in the adjacent Chiwaukum Schist. The co-axial, superposed folding in the Tonga Formation and the overall N-S arrangement of the component fold generations suggests a strong component of east-west shortening in the foreland of the Cascades core. Fold geometries account for the inverted metamorphic zonation as well as control the localization of plutons, which also elongate parallel to the regional fold axes. The central and southern and portion of Tonga Formation records subsequent contact ('M2') and regional ('M3') metamorphism, and appears to be a

  3. 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

  4. 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

  5. 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

  6. A juvenile lizard specimen with well-preserved skin impressions from the Upper Jurassic/Lower Cretaceous of Daohugou, Inner Mongolia, China

    NASA Astrophysics Data System (ADS)

    Evans, S. E.; Wang, Y.

    2007-06-01

    Lizards are now relatively well known from the Yixian Formation of northeastern China. In this study, we describe a juvenile lizard from a fossil horizon at Daohugou, Inner Mongolia. These beds predate the Yixian Formation, and are probably Late Jurassic or earliest Cretaceous in age. The new specimen thus documents the first lizard material from the Daohugou locality and is the earliest lizard skeleton from China. Comparisons with developmental stages of modern lizards suggest the Daohugou lizard is a hatchling. Although tiny, the specimen is notable in preserving exquisite skin impressions showing the variation in scalation across the body, the shape and position of the cloacal outlet, and details of the manus and pes. These are the earliest recorded lepidosaurian skin traces. In its general proportions and the possession of paired frontals, the small Daohugou lizard resembles both the Yixian taxon Yabeinosaurus tenuis and the questionable Jeholacerta formosa, but it differs from the latter in scalation and, based on other characters, may be distinct from both.

  7. Reservoir development in the Shualba formation (lower Cretaceous) at Al Barakah and Safah Fields Oman - similarities

    SciTech Connect

    Prezbindowski, D.R. ); Benmore, W.C. )

    1996-01-01

    A detailed sedimentological and diagenetic study of the upper Shuaiba in the Al Barakah and Safah Fields indicates that the critically important development of secondary micro-intercrystalline porosity postdates early meteoric water diagenesis. The Shuaiba at Al Barakah and Safah Fields consists of shoaling upward carbonate depositional cycles. The main reservoir is developed in the upper cycle as discrete carbonate accumulations centered around rudist/algal biogenic build-ups with surrounding, deeper water non-reservoir facies. Reservoir porosity is dominated by secondary micro-intercrystalline (chalky) porosity. A moderate sedimentological control on secondary porosity development is evident. The best reservoir quality is developed in the coarse-grained, skeletal-rich packstones associated with the carbonate build-ups. Although the presence of a regional unconformity at the top of the Shuaiba has commonly been thought to be responsible for reservoir porosity development, a lack of petrographic and geochemical evidence for early meteoric water diagenesis has made an evaluation of this reservoir development model difficult. Cores taken of the Shuaiba and Nahr Umr contact in the Safah and Al Barakah Fields indicate that meteoric diagenesis did occur, occluding early porosity. Reservoir porosity development significantly postdates early meteoric water diagenesis, equant spar calcite cementation and stylolitization. Porosity was formed by the dissolution of the micritic components in the limestones during burial. Reservoir porosity development in these fields is not related to the regional input of meteoric water at the Shuaiba unconformity surface.

  8. Reservoir development in the Shualba formation (lower Cretaceous) at Al Barakah and Safah Fields Oman - similarities

    SciTech Connect

    Prezbindowski, D.R.; Benmore, W.C.

    1996-12-31

    A detailed sedimentological and diagenetic study of the upper Shuaiba in the Al Barakah and Safah Fields indicates that the critically important development of secondary micro-intercrystalline porosity postdates early meteoric water diagenesis. The Shuaiba at Al Barakah and Safah Fields consists of shoaling upward carbonate depositional cycles. The main reservoir is developed in the upper cycle as discrete carbonate accumulations centered around rudist/algal biogenic build-ups with surrounding, deeper water non-reservoir facies. Reservoir porosity is dominated by secondary micro-intercrystalline (chalky) porosity. A moderate sedimentological control on secondary porosity development is evident. The best reservoir quality is developed in the coarse-grained, skeletal-rich packstones associated with the carbonate build-ups. Although the presence of a regional unconformity at the top of the Shuaiba has commonly been thought to be responsible for reservoir porosity development, a lack of petrographic and geochemical evidence for early meteoric water diagenesis has made an evaluation of this reservoir development model difficult. Cores taken of the Shuaiba and Nahr Umr contact in the Safah and Al Barakah Fields indicate that meteoric diagenesis did occur, occluding early porosity. Reservoir porosity development significantly postdates early meteoric water diagenesis, equant spar calcite cementation and stylolitization. Porosity was formed by the dissolution of the micritic components in the limestones during burial. Reservoir porosity development in these fields is not related to the regional input of meteoric water at the Shuaiba unconformity surface.

  9. 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

  10. A new Early Cretaceous relative of Gnetales: Siphonospermum simplex gen. et sp. nov. from the Yixian Formation of Northeast China

    PubMed Central

    2010-01-01

    Background Knowledge on fossil and evolutionary history of the Gnetales has expanded rapidly; Ephedra and ephedroids as well as the Gnetum-Welwitschia clade are now well documented in the Early Cretaceous. However, hypotheses on evolutionary relationships among living and fossil species are hampered by restricted knowledge of morphological variation in living groups and recent studies indicate that gnetalean diversity and character evolution may be more complex than previously assumed and involve additional extinct groups (Bennettitales, Erdtmanithecales and unassigned fossil taxa). Results Here we describe a new fossil related to Gnetales, Siphonospermum simplex from the Early Cretaceous Yixian Formation, an impression/compression of a reproductive shoot. The slender main axis bears one pair of opposite and linear leaves with primary parallel venation. The reproductive units are ovoid, without supporting bracts and borne on one median and two lateral branches. The most conspicuous feature of the fossil is the long, thread-like micropylar tube formed by the integument. Each ovule is surrounded by two different layers representing one or two seed envelopes; an inner sclerenchymatous layer and an outer probably parenchymatous layer. Conclusions The vegetative and reproductive features of Siphonospermum simplex exclude a relationship to any other group than the Gnetales. A combination of opposite phyllotaxis, linear leaves and ovules surrounded by seed envelope(s) and with a long exposed micropylar tube are known only for extant and extinct Gnetales. Siphonospermum simplex constitutes a new lineage within the Gnetales. Its morphology cannot be directly linked to any previously known plant, but the organization of the reproductive units indicates that it belongs to the Gnetum-Welwitschia clade. Based on the absence of cone bracts and the inferred histology of the seed envelope(s) it could be related to Gnetum, however, there are also affinities with the ephedran

  11. New material of Longipteryx (Aves: Enantiornithes) from the Lower Cretaceous Yixian Formation of China with the first recognized avian tooth crenulations.

    PubMed

    Wang, Xuri; Shen, Caizhi; Liu, Sizhao; Gao, Chunling; Cheng, Xiaodong; Zhang, Fengjiao

    2015-01-01

    We report on a new specimen of Longipteryx chaoyangensis from the Lower Cretaceous Yixian Formation in Chaoyang, Liaoning Province, China. The new material preserves previously unknown tooth crenulations. This is the first recognized tooth crenulations within Aves. It not only provides new information regarding the anatomy of the Longipteryx, but also sheds new light on the trophic specialization of this genus and even this family. It was discovered from the Yixian Formation, which is older than the Longipteryx chaoyangensis bearing-Jiufotang Formation. This new discovery also expands the known stratigraphic range of Longipteryx. PMID:25947529

  12. 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

  13. 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.

  14. 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

  15. 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

  16. Basement controls on rifting and the associated formation of ocean transform faults—Cretaceous continental extension of the southern margin of Australia

    NASA Astrophysics Data System (ADS)

    Miller, John McL.; Norvick, Martin S.; Wilson, Christopher J. L.

    2002-11-01

    The initial stage of continental extension between Australia and Antarctica was associated with lateral changes in extension direction along the margin that reflects the three-dimensional nature of strain during continental rifting. In the Cretaceous Otway Basin, this change in extension direction was related to substantial rheological differences in the lithosphere across the boundary between two Paleozoic fold belts, the Lachlan and Delamerian, with the net extension direction at a high angle to this boundary. The initial Early Cretaceous rifting preserved within the onshore Otway Basin has two main structural subdomains in the eastern and western Otway Basins distinguished by different structural trends of Early Cretaceous normal faulting. This is not controlled by a variation in preexisting structural weaknesses within the underlying Paleozoic basement because the same geometry of extensional structures also occurs within the basement to the north irrespective of the preexisting structural grain. The eastern Otway Basin is dominated by NE-striking NW-dipping normal faults. In the western Otway Basin, the faults define arrays of predominantly NE-dipping or SW-dipping faults separated by wide accommodation zones defined by folding and variably striking and dipping faults. The partitioning of strain along the boundary between the eastern and western Otway Basins is accommodated by a progressive change in strike of faults and not via a transfer fault. Younger rifting in the Late Cretaceous had a similar extension direction in the western Otway basin, but had a dominant seaward dip, extension appears to have been hindered in the eastern Otway basin by a Proterozoic/Paleozoic basement feature. These factors produced a region of diverging extension along the lithospheric boundary between the Delamerian and Lachlan Fold Belts that lead to failure along this boundary and the formation of a localized sinistral trans-tensional graben, the Shipwreck trough, in the early

  17. 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.

  18. The earliest known tyrannosaur from the Lower Cretaceous of Thailand

    NASA Astrophysics Data System (ADS)

    Buffetaut, Eric; Suteethorn, Varavudh; Tong, Haiyan

    1996-06-01

    THE Tyrannosauridae were the dominant large carnivorous dinosaurs in Asia (excluding India) and western North America during the Late Cretaceous period1-3. Most of them are from the Campanian and Maastrichtian ages, and very little is known about their earlier history, although scanty remains have been reported from the early part of the Upper Cretaceous4-7. We describe a newly discovered incomplete skeleton of a large theropod from the Early Cretaceous Sao Khua Formation of northeastern Thailand as an early and primitive representative of the Tyrannosauridae. This new taxon, which is at least 20 million years older than the earliest previously known tyranno-saurids, suggests that the early evolution of tyrannosaurids may have taken place in Asia.

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. 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

  4. Paleomagnetism of Upper Jurassic to Lower Cretaceous volcanic and sedimentary rocks from the western Tarim Basin and implications for inclination shallowing and absolute dating of the M-0 (ISEA?) chron

    NASA Astrophysics Data System (ADS)

    Gilder, Stuart; Chen, Yan; Cogné, Jean-Pascal; Tan, Xiaodong; Courtillot, Vincent; Sun, Dongjiang; Li, Yongan

    2003-02-01

    Stepwise demagnetization isolates a stable magnetic component in 13 sites of basalt flows and baked sediments dated at 113.3±1.6 Ma from the Tuoyun section, western Xinjiang Province, China. Except for one flow from the base of the ˜300 m thick section, the rest have exclusively reversed polarity. The sequence correlates with chron M-0 in some geomagnetic polarity time scales, which potentially places the section just before the start of the Cretaceous Long Normal polarity superchron. Five of 11 sites of Early Cretaceous red beds that underlie the basalts possess coherent directions that pass both fold and reversals tests. Six sites of Upper Jurassic red beds have a magnetic component that was likely acquired after folding in the Tertiary. The mean paleolatitude of the Lower Cretaceous red beds is 11° lower than that of the Lower Cretaceous basalts suggesting the red beds underestimate the true field inclination. We further test this result by calculating the paleolatitudes to a common point of the available Early Cretaceous to Present paleomagnetic poles from red beds and volcanic rocks from central Asian localities north of the Tibetan Plateau. We find that paleolatitudes of volcanic rocks roughly equal the paleolatitudes calculated from the reference Eurasian apparent polar wander path (APWP) and that paleolatitudes of red beds are generally 10-20° lower than the paleolatitudes of volcanic rocks and those predicted from the reference curve. Our study suggests that central Asian red beds poorly record the Earth's field inclination, which leads to lower than expected paleolatitudes. Good agreement in paleolatitudes from volcanic rocks and the Eurasian APWP argues against proposed canted and non-dipole field models.

  5. 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

  6. 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).

  7. 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.

  8. Devonian salt dissolution-collapse breccias flooring the Cretaceous Athabasca oil sands deposit and development of lower McMurray Formation sinkholes, northern Alberta Basin, Western Canada

    NASA Astrophysics Data System (ADS)

    Broughton, Paul L.

    2013-01-01

    The sub-Cretaceous paleotopography underlying giant Lower Cretaceous Athabasca oil sands, northern Alberta, has an orthogonal lattice pattern of troughs up to 50 km long and 100 m deep between pairs of cross-cutting lineaments. These structures are interpreted to have been inherited from a similar pattern of dissolution collapse-subsidence troughs in the underlying Middle Devonian salt beds. Removal of more than 100 m of halite salt fragmented the overlying Upper Devonian strata into fault blocks and collapse breccias that subsided into the underlying dissolution troughs. The unusually low 1:2 to 1:3 thickness ratios of halite salts to the overlying strata resulted in the Upper Devonian strata collapse-subsidence into underlying salt dissolution troughs being more cataclysmic during the first phase of salt removal. The second phase of slower but complete salt removal between the earlier troughs resulted in a more gradual subsidence of the overlying strata. This obliterated the earlier pattern of giant cross-cutting dissolution troughs bounded by major lineaments. The collapse breccia fabrics underlying the earlier troughs differ from those from areas between the troughs. Collapse breccias underlying the large troughs often have crushed fabrics distributed in zones that rapidly pinched out between fault blocks. Breccias between troughs developed as giant mosaics of detached carbonate blocks that formed breccia pipe complexes. Multiple sinkholes up to 100 m deep aligned along multi-km linear valley trends that dissected the sub-Cretaceous paleotopography. These sinkhole trends formed orthogonal patterns inherited from underlying lattice of NW-SE and NE-SW salt structured lineaments. These cross-cutting sinkhole trends have a smaller 5 km scale reticulate pattern similar to the giant 50 km scale pattern of collapse-subsidence troughs. Other sinkholes developed as lower McMurray strata sagged when underlying Devonian fault blocks and breccia pipes differentially

  9. 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.

  10. 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

  11. 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

  12. A new upper jurassic ophthalmosaurid ichthyosaur from the Slottsmøya Member, Agardhfjellet formation of central Spitsbergen.

    PubMed

    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

  13. Fractures Patterns of Tight Carbonates of Upper Jurassic Arab-D Member and Upper Jubaila Formation Outcrops, Central Saudi Arabia

    NASA Astrophysics Data System (ADS)

    Abdullatif, Osman; Abdlmutalib, Ammar

    2015-04-01

    This study investigates the fracture patterns of the upper Jurassic Arab-D member and upper Jubaila Formation outcropping in central Saudi Arabia. These strata represent the outcrop equivalent for Arab-D reservoir. The upper Jubaila Formation was deposited in the lower to upper slope to ramp crest leading to deposition Stromatoporoid lithofacies association, while Arab-D member deposited under deep to shallow lagoonal settings including skeletal bank and tidal flat lithofacies associations. This study utilized high resolution outcrop scale integrated fracture analysis, sedimentological and stratigraphical approach and methods.The field data included lithofacies, stratigraphic hierarchy, cyclicity and fracture measurements of orientation, length, spacing, intensity, and aperture. The Arab-D member is affected by five fracture patterns: (a) regular large scale fractures NW striking, several meters widely spaced, vertically dipping and cutting through several beds; (b) regular medium scale fractures striking NE and vertically dipping, moderately spaced and extending from two to three meters in length and cut through two or three beds; (c) regular small scale fractures that are arrested near the bed boundary vertically dipping and having less than one meter length and spacing; (d) irregular fractures filled with chemically weathered materials; (e) large scale fractures oriented perpendicular to the first fracture pattern in (a) along the outcrop strike and also cut on the top of the resistive sandy grainstone lithofacies of Arab D member. In contrast, the Upper Jubaila Formation is characterized mostly by medium scale NW and NE striking fractures that near vertically dipping and extended within one or two beds. Irregular small scale fractures also occur within parts of the beds of this group.Fracture formation and development in the Arab D and Jubaila Formation are partially attributed to regional tectonics affected the study area and locally to stratigraphic and

  14. 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

  15. 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.

  16. 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

  17. Upper Miocene Echinoderms and Crabs OF Mishan Formation in Firuzabad Fars, Iran (Zagros Mountain)

    NASA Astrophysics Data System (ADS)

    Dehbozorgi Dehbozorgi, Mehdi; Sabouhi Sabouhi, Mostafa; Nabavi Nabavi, Hamid

    2010-05-01

    The out crapes of Mishan Formation located in Aghar area(Firuzabad city) south west of Fars and 70km south west of Firuzabad. this Formation mostly consist of limestone, marly limestone and marlstone with 800m thickness. 6key beds distinctive from limestone beds are recognized in this area. In order to paleontological studies Mishan formation Middle- Upper Miocene beds in south west Firuzabad city investigated. Upper and lower boundaries of Mishan formation are conformable with Razak and Aghajari formations. In addition, assemblage of Gastropods, Bivalves, calcareous alga, bentic foraminifera, beryozoa were obtained that showing shallow sedimentation environment and open marine platform. Echinoderms are assigned to order Clypeasteroida and genus Scutella faujast, Schizaster sp, Oligopygus wetherbyi, Periarchus lyelli. Crabs be assigned to subphylum Crustacea and order Decapods: Portunus cf. gibbesii(1859). With due attention to rang and distribution of the Macrofossils, 5 local assmblage biozone were recognized, that is confirming time limit from Early- Upper Miocene.

  18. 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.

  19. 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

  20. Ooid mineralogy and diagenesis of upper Mississippian Pitkin Formation, Arkansas

    SciTech Connect

    Heydari, E.; Snelling, R.D.; Dawson, W.C.; Machain, M.L. )

    1989-08-01

    The Pitkin formation is a marine oolitic-bioclastic limestone exhibiting shoal, lagoonal, beach, and tidal-channel facies. Ooids formed on the Pitkin carbonate shelf show lateral and vertical variations in original mineralogy. In a section south of Mountain View, Arkansas, the lower marine shoal and shoreface facies are composed of originally aragonitic ooids. These ooids are replaced by neomorphic calcite and exhibit elevated strontium and low magnesium concentrations. The overlying lagoonal facies are composed of originally calcite ooids that have retained their original radial fabrics. These ooids exhibit low strontium and high magnesium concentration. Ooids in sections to the west of Mountain View are all calcitic. Early diagenesis of the formation is dominated by marine cementation. Postdepositional diagenesis encompasses extensive dissolution of originally aragonite and magnesian calcite components, precipitation of a late unzoned ferroan calcite, and minor amounts of saddle dolomite. Grainstone units lack any intergranular porosity. Pressure solution contacts among grains in grainstones are generally uncommon. Cementation alone is responsible for destruction of all of the original porosity in these rocks. Intensive pressure solution is observed only in packstone units not affected by early marine cementation.

  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. 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.

  3. 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

  4. 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

  5. Evidence for the correlation of the upper part of the Llewellyn Formation (Pennsylvania Anthracite region), with the Monongahela Formation

    USGS Publications Warehouse

    Eggleston, J.R.; Wnuk, C.; Edmunds, W.E.

    1996-01-01

    A plant fossil assemblage from the roof shale of the No. 25 anthracite bed in Pennsylvania indicates that the upper part of the Llewellyn Formation is much younger than the lower part of the Allegheny Group or Conemaugh Group correlation that was indicated by Read and Mamay (1960). These results confirm the conclusions of Fontaine and White (1880), White (1900), and Darrah (1969) who suggested that the highest coals of the Llewellyn Formation could be equivalent to the Monongahela Group.

  6. 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

  7. Chengia laxispicata gen. et sp. nov., a new ephedroid plant from the Early Cretaceous Yixian Formation of western Liaoning, Northeast China: evolutionary, taxonomic, and biogeographic implications

    PubMed Central

    2013-01-01

    Background The extant Gnetales include three monotypic families, namely, Ephedraceae (Ephedra), Gnetaceae (Gnetum), and Welwitschiaceae (Welwitschia), all of which possess compound female cones that comprise a main axis and 1 to multiple pairs/whorls of bracts subtending a female reproductive unit or having lower pairs/whorls of bracts sterile. However, the evolutionary origin of such a reproductive architecture in Gnetales is controversial in the light of the competing anthophyte versus gnetifer hypotheses of seed plant relationships. Hence, macrofossils demonstrating the structure of compound female cones of the Gnetales should be important to decipher the early evolution of the order. Results A new ephedroid plant Chengia laxispicata gen. et sp. nov. is described from the Early Cretaceous Yixian Formation of western Liaoning, Northeast China. The fossil represents a part of a leafy shooting system with reproductive organs attached. The main shoot bears internodes and swollen nodes, from which lateral branches arise oppositely. Reproductive organs consist of female spikes terminal to twigs or axillary to linear leaves. Spikes are loosely arranged, having prominent nodes and internodes. Bracts of the spikes are decussately opposite and comprise 4—8 pairs of bracts. Each bract subtends an ellipsoid seed. Seeds are sessile, with a thin outer envelope and a distal micropylar tube. Conclusions Chengia laxispicata gen. et sp. nov. provides a missing link between archetypal fertile organs in the crown lineage of the Gnetales and compound female cones of the extant Ephedraceae. Combined with a wealth of Ephedra and ephedroid macrofossils from the Early Cretaceous, we propose a reduction and sterilization hypothesis that the female cone of the extant Ephedraceae may have stemmed from archetypal fertile organs in the crown lineage of the Gnetales. These have undergone sequentially intermediate links similar to female cones of Cretaceous Siphonospermum, Chengia, and

  8. 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.

  9. 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

  10. Paleomagnetic results from the Early Cretaceous Lakang Formation lavas: Constraints on the paleolatitude of the Tethyan Himalaya and the India-Asia collision

    NASA Astrophysics Data System (ADS)

    Yang, Tianshui; Ma, Yiming; Bian, Weiwei; Jin, Jingjie; Zhang, Shihong; Wu, Huaichun; Li, Haiyan; Yang, Zhenyu; Ding, Jikai

    2015-10-01

    To better constrain the Early Cretaceous paleogeographic position of the Tethyan Himalaya and the India-Asia collision process, a paleomagnetic study was performed on the Lakang Formation lava flows in the Cuona area in the southeastern Tethyan Himalaya. Stepwise thermal and alternating field demagnetizations successfully isolated reliable characteristic remanent magnetization (ChRM) directions that include antipodal dual polarities and pass positive fold tests at the 99% confidence level and reversal tests at 95% confidence level, indicating prefolding primary magnetizations. The distribution patterns of ChRM directions from the Lakang Formation lava flows are consistent with young lava flows at similar latitudes, suggesting that secular variation has likely been averaged out. The tilt-corrected site-mean direction for 31 sites is D = 261.6 °, I = - 68.5 ° with α95 = 3.6 °, which provides a paleopole at 26.8°S, 315.2°E (A95 = 5.7 °), corresponding to a paleolatitude of 52.2 ° ± 5.7 °S for the study area. Comparison of the paleolatitude observed from the Lakang Formation lava flows with that expected from the apparent polar wander paths of India at 130 Ma show a paleolatitude difference of ∼2.1° (∼230 km), indicating that neither a great north-south continental crustal shortening occurred between the Indian craton and the Tethyan Himalaya after 130 Ma, nor that a wide ocean separated them at that time. Comparison with reliable Cretaceous-Paleocene paleomagnetic results observed from the Tethyan Himalaya and the Lhasa terrane indicates that the latitudinal width of the Neo-Tethyan Ocean could have been up to ∼7000 km at 134-130 Ma and an extension should have existed between the Indian craton and the Tethyan Himalaya during the Late Cretaceous and Paleocene. Furthermore, reliable paleomagnetic results suggest that the India-Asia collision was a dual-collision process, consisting of a first collision of the Tethyan Himalaya with the Lhasa terrane

  11. 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.

  12. 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.

  13. Cooling history of the Upper Cretaceous Palgongsan Granite, Gyeongsang Basin, SE Korea and its tectonic implication for uplift on the active continental margin

    NASA Astrophysics Data System (ADS)

    Lim, Hyoun Soo; Lee, Yong Il

    2005-07-01

    Apatite and zircon fission track analyses were carried out to reconstruct the cooling and inferred uplift history of the Cretaceous Palgongsan Granite, Gyeongsang Basin, Korea. The Palgongsan Granite is one of the Bulguksa intrusive rocks that formed by arc-related plutonism during Late Cretaceous to Early Tertiary time. Fission track dating of the Palgongsan Granite yielded nearly concordant ages of 53 and 65 Ma for apatite and zircon, respectively. The Palgongsan Granite also shows a simple cooling pattern, which suggests that it has not been affected by any thermal event after emplacement. The cooling history derived from fission track data combined with other thermochronometric data indicates that the Palgongsan Granite experienced relatively rapid cooling in earlier stage (> 30 °C/Ma). The initial rapid cooling rate during the Late Cretaceous has been caused by the large thermal contrast between the granite body and the country rocks. After reaching thermal equilibrium with the surrounding country rocks, the cooling rate of the Palgongsan Granite was abruptly decreased in late stage. In this late stage, the decelerated cooling rate is interpreted to have been controlled by uplift and erosion processes, and the average exhumation rate is calculated to be ca. 50 m/my over the temperature range from 100 °C to the surface temperature. The cooling history of the Palgongsan Granite is in good agreement with that of the Ryoke Granitic Belt in Southwest Japan, as well as those of the Taebaeksan Range and other Bulguksa intrusive rocks in the Gyeongsang Basin. This suggests that such cooling was probably caused by regional uplift and exhumation processes on the East Asian active continental margin. Compared with the uplift rates of the Andes, the uplift rates on the eastern Pacific margin appear to be higher than those on the western Pacific margin.

  14. Cretaceous to Eocene passive margin sedimentation in Northeastern Venezuela

    SciTech Connect

    Erikson, J.P. )

    1993-02-01

    Twenty two palinspastic paleogeographic maps are presented for the Cretaceous to Eocene strata of the Serrania del Interior of northeastern Venezuela. The mapped lithologies, environmental conditions, and evolving depositional systems record [approximately]90 m.y. of dominantly marine sedimentation on the only observable Mesozoic passive margin in the Western Hemisphere. The depositional systems of the passive margin are heterogeneous at lateral (i.e., along-margin) length scales greater than [approximately]40 km. The primary lateral heterogeneity is caused by a major Lower Cretaceous deltaic system that emanated southwest of the Serrania del Interior. All important intervals, such as the laterally variable Aptian-Albian El Cantil platform limestone and the hydrocarbon source rocks of the Upper Cretaceous Querecual and San Antonio formations, are related to probable causal mechanisms and environmental conditions. Stratigraphic events have been interpreted as of either local or regional extent; based on a combination of outcrop sedimentologic analyses and regional depositional systems interpretation. The 3-dimensional distribution of depositional systems and systems tracts reveals 4-6 regional sequence boundaries separated by 4-20 m.y. Subsidence analyses support the facies interpretation of a passive margin by showing continuous, thermally dominated subsidence during the Cretaceous to Eocene interval. Subsidence and accumulation rates increased and facies changed significantly in the Oligocene, indicating the end of passive margin sedimentation and the initiation of foredeep subsidence and accumulation associated with overthrusting the eastward-advancing Caribbean Plate.

  15. Strontium-isotope stratigraphy of Upper Cretaceous rudist bivalves: Biozones, evolutionary patterns and sea-level change calibrated to numerical ages

    NASA Astrophysics Data System (ADS)

    Steuber, Thomas; Schlüter, Malte

    2012-08-01

    Numerical ages derived from strontium-isotope stratigraphy of 81 Late Turonian-Maastrichtian rudist localities from the Caribbean to Oman are used to establish stratigraphical ranges of readily identifiable taxa of rudist bivalves (Hippuritida). Based on these ranges, seven biozones for the Turonian-Maastrichtian of the central-eastern Mediterranean Tethys, and three biozones for the mid-Campanian-Maastrichtian of the Arabian Plate are established. Most of these are interval zones, each based on the first stratigraphical appearance of the nominal taxon. Micro-evolutionary patterns such as phyletic size increase have been demonstrated for some of the nominal species, as well as a trend of stratigraphical range expansion from the Turonian to the Maastrichtian. Implications of the geochronology of Late Cretaceous carbonate platforms for the biostratigraphy of other benthic fossils are briefly discussed. Three significant gaps in the stratigraphical distribution of rudist localities in the lower, middle, and uppermost Campanian, respectively, correlate with other records of sea-level change, indicating that they correspond to major eustatic sea-level falls. Only a limited number of rudist taxa is evaluated here, but the early and latest Campanian sea-level falls correspond to faunal turnover and extinction of characteristic associations of Late Cretaceous Hippuritida. The final extinction of the Hippuritida at the Cretaceous/Paleogene boundary is evaluated based on the available numerical ages of eighteen Late Maastrichtian localities. Eighteen genera are recorded at the six youngest localities, which thus have a species richness similar to older Late Cretaceous localities. While the ultimate cause for extinction of the Hippuritida must be evaluated on time scales beyond the resolution of strontium-isotope stratigraphy, the data set evaluated provides some insight into the pattern of their demise, which is considered to be the result of a high degree of endemism

  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

    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.

  17. 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. PMID:21253683

  18. Influence of Transcontinental arch on Cretaceous listric-normal faulting, west flank, Denver basin

    SciTech Connect

    Davis, T.L.

    1983-08-01

    Seismic studies along the west flank of the Denver basin near Boulder and Greeley, Colorado illustrate the interrelationship between shallow listric-normal faulting in the Cretaceous and deeper basement-controlled faulting. Deeper fault systems, primarily associated with the Transcontinental arch, control the styles and causative mechanisms of listric-normal faulting that developed in the Cretaceous. Three major stratigraphic levels of listric-normal faulting occur in the Boulder-Greeley area. These tectonic sensitive intervals are present in the following Cretaceous formations: Laramie-Fox Hills-upper Pierre, middle Pierre Hygiene zone, and the Niobrara-Carlile-Greenhorn. Documentation of the listric-normal fault style reveals a Wattenberg high, a horst block or positive feature of the greater Transcontinental arch, was active in the east Boulder-Greeley area during Cretaceous time. Paleotectonic events associated with the Wattenberg high are traced through analysis of the listric-normal fault systems that occur in the area. These styles are important to recognize because of their stratigraphic and structural influence on Cretaceous petroleum reservoir systems in the Denver basin. Similar styles of listric-normal faulting occur in the Cretaceous in many Rocky Mountain foreland basins.

  19. Taphonomy and depositional environment of a Lower Cretaceous monospecific dinosaur bone assemblage (Puesto Quiroga Member, Lohan Cura Formation), Neuquén Province, Argentina

    NASA Astrophysics Data System (ADS)

    Garrido, Alberto Carlos; Salgado, Leonardo

    2015-08-01

    The Puesto Díaz Quarry (Lohan Cura Formation, Lower Cretaceous of Neuquén Basin, Argentina) consists of a monospecific dinosaur bone assemblage that includes 126 specimens from, at least, three individuals of the rebbachisaurid sauropod Comahuesaurus windhauseni. The bonebed was originated as a debris flow of an ephemeral-river bed, in distal areas of low relief. Bones are disarticulated, three-dimensionally distributed through the host facies, showing a normal grading arrangement, which can be correlated with the size, shape and hydraulic behavior inferred for each specimen. Taphonomic evidence suggests that the bones did not experience a prolonged transport, and that these were quickly buried by the debris flow event. The fact that there are more than one individual of the same species suggests a mass mortality by a catastrophic event. Scattered skeletal elements would indicate that the corpses must have been subaerially exposed, long enough to allow disarticulation by scavenging, decay, and defleshing.

  20. Detrital zircon U-Pb and (U-Th)/He double-dating of Upper Cretaceous-Cenozoic Zagros foreland basin strata in the Kurdistan Region of northern Iraq

    NASA Astrophysics Data System (ADS)

    Barber, D. E.; Stockli, D. F.; Koshnaw, R. I.; Horton, B. K.; Tamar-Agha, M. Y.; Kendall, J. J.

    2014-12-01

    The NW Zagros orogen is the result of the multistage collisional history associated with Late Cretaceous-Cenozoic convergence of the Arabian and Eurasian continents and final closure of Neotethys. Siliciclastic strata preserved within a ~400 km segment of the NW Zagros fold-thrust belt and foreland basin in the Iraqi Kurdistan Region (IKR) provide a widespread record of exhumation and sedimentation. As a means of assessing NW Zagros foreland basin evolution and chronostratigraphy, we present coupled detrital zircon (DZ) U-Pb and (U-Th)/He geo-thermochronometric data of Upper Cretaceous to Pliocene siliciclastic strata from the Duhok, Erbil, and Suleimaniyah provinces of IKR. LA-ICP-MS U-Pb age analyses reveal that the foreland basin fill in IKR in general was dominantly derived from Pan-African/Arabian-Nubian, Peri-Gondwandan, Eurasian, and Cretaceous volcanic arc terrenes. However, the provenance of these strata varies systematically along strike and through time, with an overall increase in complexity upsection. DZ age distribution of Paleocene-Eocene strata is dominated by a ~95 Ma grain age population, likely sourced from the Late Cretaceous Hassanbag-Bitlis volcanic arc complex along the northern margin of Arabia. In contrast, DZ U-Pb age distributions of Neogene strata show a major contribution derived from various Eurasian (e.g., Iranian, Tauride, Pontide; ~45, 150, 300 Ma) and Pan-African (~550, 950 Ma) sources. The introduction of Eurasian DZ ages at the Paleogene-Neogene transition likely records the onset of Arabian-Eurasian collision. Along strike to the southeast, the DZ U-Pb spectra of Neogene strata show a decreased percentage of Pan-African, Peri-Gondwandan, Tauride, and Ordovician ages, coupled with a dramatic increase in 40-50 Ma DZ ages that correspond to Urumieh-Dokhtar magmatic rocks in Iran. Combined with paleocurrent data, this suggests that Neogene sediments were transported longitudinally southeastward through an unbroken foreland basin

  1. 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

  2. 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…

  3. Late Cretaceous multicolored shales and phosphatic sedimentary rocks in Egypt

    SciTech Connect

    Glenn, C.R.; Garrison, R.E.; Arthur, M.A.

    1983-03-01

    Upper Cretaceous transitional fluvial to marine variegated shale (upper Nubia Formation) and the fully marine Duwi (phosphate) Formation occur as thin, widespread, shallow-marine deposits in an east-west-trending belt spanning the lower-middle latitudes of Egypt. On a larger scale, the phosphoritic rocks in Egypt represent but a small portion of a laterally extensive Middle Eastern-North African phosphogenic province of Upper Cretaceous-Lower Tertiary age that accounts for accumulation of minable marine phosphate in excess of 70 billion tons. Phosphorites, porcelanites/cherts, organic carbon-rich shales, glauconitic sandstones, and bioclastic and fine-grained carbonate rocks variously reflect major hemipelagic and shallow-water carbonate sedimentation. Biosiliceous hemipelagic deposits, now diagenetically altered to procelanite and chert, reflect low energy depositional conditions that were periodically interrupted by high energy, possibly storm-induced currents and/or down-slope redeposition. Both dark shales and porcelanites locally contain abundant organic matter and are commonly finely laminated. Porcelanites and black shales are phosphatic, containing phosphatic grains identical, morphologically and chemically, to those found in associated phosphorites, and are probably the source from which the phosphorites were derived. The organic carbon-rich shales of the Duwi Formation appear to be quite laterally extensive and may, depending on thermal maturity, represent potential hydrocarbon source rocks in other portions of the region (e.g., Western Desert, Gulf of Suez), where they are more deeply buried.

  4. A review of paleogeographical and chronostratigraphical distribution of mesoeucrocodylian species from the upper Cretaceous beds from the Bauru (Brazil) and Neuquén (Argentina) groups, Southern South America

    NASA Astrophysics Data System (ADS)

    Candeiro, Carlos Roberto A.; Martinelli, Agustín G.

    2006-11-01

    This article offers a detailed overview of mesoeucrocodylian assemblages recovered from the Late Cretaceous southern South America Bauru and Neuquén groups as a result of extensive research during the past 110 years. The Bauru (Brazil) and Neuquén (Argentina) groups yield numerous mesoeucrocodylian remains, mainly of Turonian-late Maastrichtian (Late Cretaceous) age. The majority of the discoveries were made in the Adamantina and Marília formations of Minas Gerais and São Paulo states, Brazil, and Candeleros and Bajo de la Carpa formations of Neuquén and Río Negro provinces, Argentina. Sixty formally described species of mesoeucrocodylians are recognized on the basis of disarticulated materials; among them, notosuchians, sebecosuchians, and peirosaurids are the best represented. At least one species is common to the Bauru and Neuquén groups, and close phylogenetic affinities are postulated for the remaining taxa. The fossil record of these two South American units shows three main peaks of diversity: in the Cenomanian of Argentina, the Santonian of Argentina and Brazil, and the Maastrichtian of Brazil. The absence of notosuchians and sebecosuchians in the late Campanian-Maastrichtian of Patagonia is coincident with the paleoenvironmental changes in that landmass by that time, as well as with the increase in diversity of several groups of theropod dinosaurs. In contrast, highly specialized carnivorous mesoeucrocodylians are abundant in the Maastrichtian of the Bauru group of Brazil, whereas other tetrapod carnivorous groups are scarcely represented.

  5. Stratigraphy of the Cretaceous-Tertiary and Paleocene-Eocene transition rocks of Big Bend National Park, Texas

    SciTech Connect

    Schiebout, J.A.; Rigsby, C.A.; Rapp, S.D.; Hartnell, J.A.; Standhardt, B.R.

    1987-05-01

    The marine to terrestrial transition in the Big Bend area falls within the Late Cretaceous Aguja Formation, and, in light of new biostratigraphic data resulting from screening for small vertebrates and magneto-stratigraphic data, the Cretaceous-Tertiary boundary falls within the Javelina Formation, which includes the first red banding produced by oxidation of overbank fluvial mudstones. No record of a catastrophic event is apparent in the Javelina Formation. The Javelina, Black Peaks, and Hannold Hill Formations and the Big Yellow Sandstone Member of the Canoe Formation record increasing uplift in the region, culminating in uplift and volcanism in the Chisos mountains, the source for upper Canoe Formation sediments. The sequence of changes produced by this trend and by unroofing in source highlands to the west is sufficiently gradual that the Javelina through Black Peaks units are not lithostratigraphically distinct at the formation level and therefore are reduced to member status, and placed, along with the Big Yellow Sandstone Member, within the redefined Tornillo Formation. The Aguja Formation and the Tornillo Formation are united in the Chilicotal Group (new), which spans the deposits from the first significant influxes of terrestrial sediments, formed as the Cretaceous sea retreated, up to the beginning of local volcanism in the Chisos. The volcanic strata of the upper Canoe Formation are reassigned to the Chisos Formation. 46 references.

  6. Provenance and paleogeography of the Late Cretaceous Mengyejing Formation, Simao Basin, southeastern Tibetan Plateau: Whole-rock geochemistry, U-Pb geochronology, and Hf isotopic constraints

    NASA Astrophysics Data System (ADS)

    Wang, Licheng; Liu, Chenglin; Gao, Xiang; Zhang, Hua

    2014-05-01

    The Late Cretaceous Mengyejing Formation, which contains the only pre-Quaternary potash salt deposit in the Simao Basin, southeastern Tibet, is thought to be genetically related to the Maha Sarakham Formation in the Khorat Basin. The provenance and paleogeography of these two basins have been under debate, although little diagnostic evidence has been previously published. A combined analysis of whole rock geochemistry, zircon U-Pb chronology, and Hf isotopic compositions was performed to characterize the provenance of the Mengyejing Formation. These formation's sandstones are characterized by moderate chemical index of alteration (CIA) values. These values, together with plots of the Th/U-Th ratios, suggest that certain samples have undergone moderate weathering and sedimentary recycling. The major and trace elements (La/Th-Hf, Th/Sc-Zr/Sc, Eu/Eu*-Th/Sc, TiO2-Fe2O3T + MgO, Al2O3/SiO2-Fe2O3T + MgO, K2O/Na2O-SiO2) indicate that the sedimentary sources were felsic rocks from an active continental margin or continental arc with a minor amount of recycled sediment from a passive continental margin. The Mengyejing Formation contains detrital zircons primarily with U-Pb ages of 2.45-2.57 Ga, 1.8-1.9 Ga, 740-880 Ma, 410-470 Ma, and 215-300 Ma. The results reveal that the pre-Devonian zircons are derived from the recycled sediments of the Yangtze block originating in the Qinling Orogenic Belt, and they share this provenance with the coeval sediments in the Khorat Basin. The magmatic rocks of the Ailaoshan and Lincang areas are responsible for supplying the Devonian to Triassic detrital zircons. These provenance data combined with published paleocurrent results suggest that the Simao Basin was situated on the western margin of the Khorat Basin during the Late Cretaceous. The basins were connected when marine incursion occurred. We propose that pre-Devonian materials from the southwestern Sichuan Basin first supplied detritus to the Simao Basin and subsequently to the Khorat

  7. Cretaceous eustasy revisited

    NASA Astrophysics Data System (ADS)

    Haq, Bilal U.

    2014-02-01

    Eustatic sea-level changes of the Cretaceous are reevaluated based on a synthesis of global stratigraphic data. A new terminology for local/regional or relative sea-level changes (eurybatic shifts) is proposed to distinguish them from global (eustatic) sea-level changes, with the observation that all measures of sea-level change in any given location are eurybatic, even when they include a strong global signal. Solid-earth factors that influence inherited regional topography and thus modify physical measures of amplitude of the sea-level rises and falls locally are reviewed. One of these factors, dynamic topography (surface expression of mass flow in the upper mantle on land- and seascapes), is considered most pertinent in altering local measures of amplitude of sea-level events on third-order time scales (0.5-3.0 Myr). Insights gained from these models have led to the reconciliation of variance between amplitude estimates of eurybatic shifts in any given region and global measures of eustatic changes. Global estimates of third-order events can only be guesstimated at best by averaging the eurybatic data from widely distributed time-synchronous events. Revised curves for both long-term and short-term sea-level variations are presented for the Cretaceous Period. The curve representing the long-term envelope shows that average sea levels throughout the Cretaceous remained higher than the present day mean sea level (75-250 m above PDMSL). Sea level reached a trough in mid Valanginian (~ 75 m above PDMSL), followed by two high points, the first in early Barremian (~ 160-170 m above PDMSL) and the second, the highest peak of the Cretaceous, in earliest Turonian (~ 240-250 m above PDMSL). The curve also displays two ~ 20 Myr-long periods of relatively high and stable sea levels (Aptian through early Albian and Coniacian through Campanian). The short-term curve identifies 58 third-order eustatic events in the Cretaceous, most have been documented in several basins, while

  8. An Upper Turonian fine-grained shallow marine stromatolite bed from the Muñecas Formation, Northern Iberian Ranges, Spain

    NASA Astrophysics Data System (ADS)

    Rodríguez-Martínez, M.; Sánchez, F.; Walliser, E. O.; Reitner, J.

    2012-07-01

    A fine-grained stromatolite bed, laterally continuous on the kilometer scale and with small synoptic relief, crops out in the Muñecas Formation in the Northern Iberian Ranges. The Muñecas Fm. was deposited during the late Turonian on a shallow water platform in the Upper Cretaceous intracratonic Iberian basin. The stromatolite bed has a tabular to domed biostromal macrostructure. Its internal mesostructure consists of planar, wavy to hemispherical stromatoids that display a broad spectrum of microstructures, including dense micrite, bahamite peloids, peloidal to clotted microfabrics, irregular micritic-wall tubes, which are suggestive of algae and filamentous microframeworks, which are suggestive of filamentous cyanobacteria. Various stromatolite growth stages have been linked to the dominance of different accretion processes. The accretion of the entire fine-grained stromatolite involves a complex mosaic of processes: trapping and binding of quartz-silt grains and bahamites, which form the agglutinated parts of some laminae, and microbially induced precipitation, which forms spongiostromic and micritic laminae. Tubiform and filamentous microframeworks resembling porostromatate or skeletal stromatolitic growth were also recognized. Laser ICP-MS measurements of Al, Si, Mg, Mn, Sr, S and Fe were analyzed to detect the influence of siliciclastic inputs and major trends during stromatolite accretion. Carbon and oxygen isotopic compositions from the stromatolite and associated facies were used to identify possible microbial signatures. These data describes a unique and well-preserved example of a shallow marine Upper Turonian fine-grained stromatolite.

  9. Late Cretaceous Volcaniclastics in NW Turkey

    NASA Astrophysics Data System (ADS)

    Boehm, Katharina; Wolfgring, Erik; Omer Yilmaz, Ismail; Tüysüz, Okan; Wagreich, Michael

    2015-04-01

    On the southwestern coast of the Black Sea, in the western Pontides Upper Cretaceous tuff layers are present. The tuffs are intercalated with limestones, marls and turbidites and were investigated with focus on their geochemistry, to get new insights to the arrangement of terranes and ocean basins at this time. In the region two Upper Cretaceous volcanic units can be distinguished, separated by distinct red pelagic limestone successions, belonging to the Unaz Formation. The lower volcanic unit is named Dereköy Formation and is Turonian to Santonian in age. It is thought to be deposited within extension structures, contemporaneously with rifting in the western Black Sea basin. The upper volcanic unit is called Cambu Formation. According to biostratigraphic data it is deposited throughout Campanian, when spreading in the western Black Sea basin started. Interpreted as submarine deposits, element mobility has to be taken into account when interpreting geochemical ICP-MS data of the volcaniclastics. Multiple discrimination diagrams with suitable proxies elucidate the type of volcanism and contribute to reconstruction of the tectonic setting. The classified rock types range from basaltic to rhyodacitic in both volcanic formations. Basically degree of differentiation and alkalinity are the parameters looked at, when determining rock types of the volcanic eruption. Further volcanic series are specified as calc-alkaline to shoshonitic. Moreover, a volcanic arc setting seems to be the most likely case, following several discrimination diagrams, as well as normalized multi-element plots. This tectonic setting can be discussed in connection with paleo-tectonic reconstructions. Most cited in literature nowadays are models favoring a northward subduction of the northern branch of Neotethys, creating an extensional setting north of the Pontides. This kind of back arc extension is interpreted as the reason of a southward drift of the Istanbul continental fragment from Eurasia

  10. Rahiolisaurus gujaratensis, n. gen. n. sp., A New Abelisaurid Theropod from the Late Cretaceous of India

    NASA Astrophysics Data System (ADS)

    Novas, Fernando E.; Chatterjee, Sankar; Rudra, Dhiraj K.; Datta, P. M.

    Systematic excavations in the fluvial mudstone unit of the Upper Cretaceous Lameta Formation near Rahioli village in Kheda District, Gujarat, have yielded a large-bodied (~8 m long) abelisaurid theropod, Rahiolisaurus gujaratensis, gen. et sp. nov. Abundant skeletal remains represent this new genus and species. Rahiolisaurus provides novel information on foot morphology, hitherto little known in other abelisaurids. Rahiolisaurus gujaratensis is a gracile and slender-limbed abelisaurid that appears to be a distinctive taxon from the sympatric species Rajasaurus narmadensis.

  11. Seismic facies analysis of lacustrine system: Paleocene upper Fort Union Formation, Wind River basin, Wyoming

    SciTech Connect

    Liro, L.M.; Pardus, Y.C.

    1989-03-01

    The authors interpreted seismic reflection data, supported by well control, to reconstruct the stratigraphic development of Paleocene Lake Waltman in the Wind River basin of Wyoming. After dividing the upper Fort Union into eight seismic sequences, the authors mapped seismic attributes (amplitude, continuity, and frequency) within each sequence. Interpretation of the variation in seismic attributes allowed them to detail delta development and encroachment into Lake Waltman during deposition of the upper Fort Union Formation. These deltas are interpreted as high-energy, well-differentiated lobate forms with distinct clinoform morphology on seismic data. Prograding delta-front facies are easily identified on seismic data as higher amplitude, continuous events within the clinoforms. Seismic data clearly demonstrate the time-Transgressive nature of this facies. Downdip of these clinoforms, homogeneous shales, as evidenced by low-amplitude, generally continuous seismic events, accumulated in an interpreted quiet, areally extensive lacustrine setting. Seismic definition of the lateral extent of this lacustrine facies is excellent, allowing them to effectively delineate changes in the lake morphology during deposition of the upper Fort Union Formation. Encasing the upper Fort Union lacustrine deposits are fluvial-alluvial deposits, interpreted from discontinuous, variable-amplitude seismic facies. The authors highlight the correlation of seismic facies data and interpretation to well log data in the Frenchie Draw field to emphasize the accuracy of depositional environment prediction from seismic data.

  12. Current situation of the ichnological locality of São Domingos from the Corda Formation (Lower Cretaceous), northern Tocantins state, Brazil

    NASA Astrophysics Data System (ADS)

    de Valais, S.; Candeiro, C. R.; Tavares, L. F.; Alves, Y. M.; Cruvinel, C.

    2015-08-01

    In the 80's, Leonardi treated the presence of a vertebrate ichnological locality from the Barremian Corda Formation, Parnaíba Basin, on the left bank of the Tocantins river, near of the São Domingos town, Itaguatins, State of Tocantins, Brazil. Originally, the record was composed of at least seven in situ trackways, accounting for fifty six tracks. Since 2011, the Hydroelectric Power Plant do Estreito has begun to work, causing the development of a water reservoir 160 km upstream to the ichnological site, causing periodic and highly energetic floods over the footprints-bearing level and altering it. The imprints are poorly to moderate preserved, but it is possible to distinguish the general morphology and the spatial arrangement of the footprints. The specimens are represented by pes imprints, mostly circular to subcircular, with no digital and claw impressions. No distinguishable manus imprints are present. The trackways are relative narrow with respect to the size of the tracks, so they are considered into the Parabrontopodus-like category. The São Domingos tracks have been originally assigned to iguanodontid dinosaurs, and posteriorly related to a sauropodian origin. This idea is herein accepted, particularly to a basal sauropod, basal macronarians, or diplodocoids. Up to date, the tracks from the São Domingos locality are the only vertebrate fossil record from the Corda Formation, meaning an important contribution to the Cretaceous ichnofauna from South America.

  13. 40Ar/39Ar age of the Manson impact structure, Iowa, and correlative impact ejecta in the Crow Creek member of the Pierre Shale (Upper Cretaceous), South Dakota and Nebraska

    USGS Publications Warehouse

    Izett, G.A.; Cobban, W.A.; Dalrymple, G.B.; Obradovich, J.D.

    1998-01-01

    A set of 34 laser total-fusion 40Ar/39Ar analyses of sanidine from a melt layer in crater-fill deposits of the Manson impact structure in Iowa has a weighted-mean age of 74.1 ?? 0.1 Ma. This age is about 9.0 m.y. older than 40Ar/39Ar ages of shocked microcline from the Manson impact structure reported previously by others. The 74.1 Ma age of the sanidine, which is a melt product of Precambrian microcline clasts, indicates that the Manson impact structure played no part in the Cretaceous-Tertiary (K-T) mass extinction at 64.5 Ma. Moreover, incremental-heating 40Ar/39Ar ages of the sanidine show that it is essentially free of excess 40Ar and has not been influenced by postcrystallization heating or alteration. An age spectrum of the matrix of the melt layer shows effects of 39Ar recoil, including older ages in the low-temperature increments and younger ages in the high-temperature increments. At 17 places in eastern South Dakota and Nebraska, shocked quartz and feldspar grains are concentrated in the lower part of the Crow Creek Member of the Pierre Shale (Upper Cretaceous). The grains are largest (3.2 mm) in southeastern South Dakota and decrease in size (0.45 mm) to the northwest, consistent with the idea that the Manson impact structure was their source. The ubiquitous presence of shocked grains concentrated in a thin calcarenite at the base of the Crow Creek Member suggests it is an event bed recording an instant of geologic time. Ammonites below and above the Crow Creek Member limit its age to the zone of Didymoceras nebrascense of earliest late Campanian age. Plagioclase from a bentonite bed in this zone in Colorado has a 40Ar/39Ar age of 74.1 ?? 0.1 Ma commensurate with our sanidine age of 74.1 Ma for the Manson impact structure. 40Ar/39Ar ages of bentonite beds below and above the Crow Creek are consistent with our 74.1 ?? 0.1 Ma age for the Manson impact structure and limit its age to the interval ?? 74.5 0.1 to 73.8 ?? 0.1 Ma. Recently, two origins for the

  14. Controls on the deposition and preservation of the Cretaceous Mowry Shale and Frontier Formation and equivalents, Rocky Mountain region, Colorado, Utah, and Wyoming

    USGS Publications Warehouse

    Kirschbaum, Mark A.; Mercier, Tracey J.

    2013-01-01

    Regional variations in thickness and facies of clastic sediments are controlled by geographic location within a foreland basin. Preservation of facies is dependent on the original accommodation space available during deposition and ultimately by tectonic modification of the foreland in its postthrusting stages. The preservation of facies within the foreland basin and during the modification stage affects the kinds of hydrocarbon reservoirs that are present. This is the case for the Cretaceous Mowry Shale and Frontier Formation and equivalent strata in the Rocky Mountain region of Colorado, Utah, and Wyoming. Biostratigraphically constrained isopach maps of three intervals within these formations provide a control on eustatic variations in sea level, which allow depositional patterns across dip and along strike to be interpreted in terms of relationship to thrust progression and depositional topography. The most highly subsiding parts of the Rocky Mountain foreland basin, near the fold and thrust belt to the west, typically contain a low number of coarse-grained sandstone channels but limited sandstone reservoirs. However, where subsidence is greater than sediment supply, the foredeep contains stacked deltaic sandstones, coal, and preserved transgressive marine shales in mainly conformable successions. The main exploration play in this area is currently coalbed gas, but the enhanced coal thickness combined with a Mowry marine shale source rock indicates that a low-permeability, basin-centered play may exist somewhere along strike in a deep part of the basin. In the slower subsiding parts of the foreland basin, marginal marine and fluvial sandstones are amalgamated and compartmentalized by unconformities, providing conditions for the development of stratigraphic and combination traps, especially in areas of repeated reactivation. Areas of medium accommodation in the most distal parts of the foreland contain isolated marginal marine shoreface and deltaic sandstones

  15. Geochemistry of the Cretaceous coals from Lamja Formation, Yola Sub-basin, Northern Benue Trough, NE Nigeria: Implications for paleoenvironment, paleoclimate and tectonic setting

    NASA Astrophysics Data System (ADS)

    Sarki Yandoka, Babangida M.; Abdullah, Wan Hasiah; Abubakar, M. B.; Hakimi, Mohammed Hail; Adegoke, Adebanji Kayode

    2015-04-01

    The Cretaceous coals of Lamja Formation located in Yola Sub-basin of the Northern Benue Trough, northeastern Nigeria, were analyzed based on a combined investigation of organic and inorganic geochemistry to define the paleodepositional environment condition, organic matter source inputs and their relation to paleoclimate and tectonic setting. The total organic carbon and sulfur contents of Lamja Formation coals ranges from 48.2%-67.8% wt.% and 0.42%-0.76% wt.%, respectively, pointing their deposition in freshwater environment with inferred marine influence during burial. Biomarkers and chemical compositions provide evidence for a major contribution of land-derived organic matter, with minor aquatic organic matter input. Minerals such as quartz, pyrite, kaolinite, illite, montmorillonite and calcite were present in the coals, suggesting that these minerals were sourced from terrigenous origin with slightly marine influence, considered as post-depositional. This is consistent with a significant amount of the oxides of major elements such as SiO2, Fe2O3, Al2O3, TiO2, CaO, and MgO. The investigated biomarkers are characterized by dominant odd carbon numbered n-alkanes (n-C23 to n-C33), moderately high Pr/Ph ratios (1.72-3.75), very high Tm/Ts ratios (18-29), and high concentrations of regular sterane C29, indicating oxic to relatively suboxic conditions, delta plain marine environment of deposition with prevalent contribution of land plants and minor aquatic organic matter input. Concentrations of trace elements such as Ba, Sr, Cr, Ni, V, Co and their standard ratios also suggested that the organic matter was deposited under oxic to relatively suboxic conditions, which is in parts deposited under marine influenced. Some standard binary plots of SiO2 versus (Al2O3 + K2O + Na2O) indicate a semi-arid paleoclimatic condition whereas log SiO2 versus (K2O/Na2O) also revealed passive continental margin setting. The inferred tectonic setting is in agreement with the tectonic

  16. Geochemistry of carbonate cements in Cretaceous sandstones, southeast Benue Trough, Nigeria: Implications for geochemical evolution of formation waters

    NASA Astrophysics Data System (ADS)

    Odigi, Minapuye I.; Amajor, Levi C.

    2010-05-01

    Carbonate cements including calcite, siderite, dolomite/ankerite were formed throughout the diagenetic history of the Asu River Group, Eze-Aku Group and Campano-Maastrichtain proto-Niger Delta sequences were analyzed for their major and trace element (Fe, Mn, Mg, Ca and Sr) and isotopic compositions. The earliest, ferroan carbonate cement has the following mean major and trace element concentration: Fe - 0.11 wt.%; Mn - 0.43 wt.%; Mg - 2.16 wt.%; Sr - 1050 ppm. The late ferroan has the following mean compositions: Fe - 0.48 wt.%; Mn - 0.22 wt.%; Mg - 0.25 wt.%; Sr - 1010 ppm. Earliest Fe-calcites, formed prior to significant compaction of the sediments, are relatively enriched in Mg (up to 4.12 mol.%), and have δ 18O values between -4.45% and -6.898% PDB close to the ideal original Cretaceous marine pore waters. Late calcites are relatively Fe-calcites (up to 4.2 mol.%). The earliest ferroan calcite occurs in both the Albian Asu River Group and Eze-Aku Group while late ferroan occurs in the three lithostratigraphic units studied. These geochemical variations appear to have resulted principally to reflect changes in pore water chemistry during diagenesis. The high value of Sr in cements is most likely due to interaction between pore waters and Sr-rich clay and possibly feldspar in the three lithostratigraphic units studied. Pore water Fe 2+ concentration was probably controlled by diagenetic alterations involving Fe-bearing minerals (e.g. pyrite precipitation). The low δ 18O value of some calcite cements (-11.62‰, -12.66‰, -14.31‰ PDB) suggests that an influx of meteoric water may have occurred in the Turonian-Coniacian, although the low value could also result from an abnormal geothermal gradient associated with tectonic activity in the trough. The elemental and isotopic composition of these cements varies as a function of the time of precipitation.

  17. Cretaceous paleogeography of Peninsular California

    SciTech Connect

    Gastil, R.G.

    1986-04-01

    For the past 15 years, paleomagnetic studies on various rock types have consistently shown southern and Baja California to have been located at 10/sup 0/-17/sup 0/ lower latitude, relative to cratonal North America, than it is today. Similar studies on the Salinian block and in southwestern Oregon also indicate substantially lower latitudes for the deposition of Upper Cretaceous rocks. In seeming contradiction, apparent correlations across the Gulf of California plate boundary relate Cambrian(.) to Triassic stratal rocks of Sonora and the Great Basin to their contemporaries in Baja California, and Jurassic and Cretaceous arc rocks in the peninsula to those in mainland Mexico. Therefore, relative movement along the San Andreas system seems limited to approximately 300 km in a right-lateral direction since the Miocene. A possible accommodation to both sets of evidence places the Baja Peninsula near its present position relative to cratonal North America until about the Middle Jurassic, when it began moving relatively southeastward. This left-lateral motion placed it about 11/sup 0/ southeast by the Aptian-Albian and 17/sup 0/ southeast by the Campanian-Maestrichtian. The Late Jurassic to Late Cretaceous arcs trended southeast through Sonora, Sinaloa, and Jalisco, and then down the length of peninsular California. The right-lateral return of the peninsula began during the Late Cretaceous. The fault systems for the return motion cannot lie west of the Gulf of California, and thus, neither can the earlier left-lateral fault.

  18. New data on the stratigraphy and depositional environment for Upper Jurassic and Lower Cretaceous deposits of the Stolbovoi Island (New Siberian Islands)

    NASA Astrophysics Data System (ADS)

    Kuzmichev, A. B.; Zakharov, V. A.; Danukalova, M. K.

    2009-08-01

    The section of Mesozoic terrigenous deposits over 1200 m thick has been described, and a new geological map of the Stolbovoi Island southern half has been compiled. The inference has been made that the sedimentary sequence represents a single uniform turbidite complex, which is indivisible into lithological units and which does not show transition to shallow-marine facies either in the visible foot section or visible roof section. The complex accumulated in the foreland basin emerged on the margin of the Novosibirsk-Chukchi continental block during the Anyuian orogeny. The presence of upper Volgian deposits (Upper Jurassic) with a visible thickness of 640 m, Berriasian (Ryazanian) deposits about 100-m thick, and lower Valanginian deposits with a visible thickness of ˜200 m has been established on the basis of identification of fossils represented by remains of bivalve mollusks (the genus Buchia). Finds of upper Volgian buchias in the southeastern part of the island are inconsistent with field geological observations of the sequence of deposits. Paleontological data acquired for the island southern part suggest the presence of a transverse thrust fault, along which upper Volgian rocks were thrust over lower Neocomian rocks. The possibility of another interpretation of the data has also been considered. The correlation of the Buchia Beds of the Stolbovoi Island, Nordvik Peninsula, the basin of the Anyui River, and northern California has been carried out. The inference about a close relationship between the biota of the Stolbovoi Island and the North Pacific paleobiogeographic realm has been drawn.

  19. Synthesis of Late Cretaceous-Quaternary tectonic, sedimentary and magmatic processes and basin formation related to episodic subduction-collision in the easternmost Mediterranean region

    NASA Astrophysics Data System (ADS)

    Robertson, Alastair; Kinnaird, Timothy; McCay, Gillian; Palamakumbura, Romesh; Taslı, Kemal

    2015-04-01

    Mesozoic oceanic crust of the easternmost Mediterranean has experienced northwards subduction during Late Cretaceous-Cenozoic, either continuously or discontinuously based on kinematic evidence. Much of the existing information on sedimentation within the easternmost Mediterranean oceanic basin comes from the non-emplaced continental margins of the Levant and North Africa. In addition, sedimentary basins related to plate convergence are recorded along the northern margin of the Southern Neotethyan ocean, mainly in the Kyrenia Range of northern Cyprus and its extension into the Misis Mountains of southern Turkey, coupled with the adjacent submerged areas. In a setting of only incipient continental collision such as the easternmost Mediterranean the sedimentary basins would be expected to remain entirely submarine. In contrast, the Kyrenia Range has been strongly uplifted and subaerially exposed during Late Pliocene-Quaternary time. This allows the recognition of a number of discrete phases of sedimentary basin formation: 1. Late Cretaceous (Campanian-Maastrichtian): silicic volcanism to create a subaqueous volcaniclastic apron; 2. Maastrichtian-Paleocene: pelagic carbonate deposition interspersed with proximal gravity flows and within-plate type alkaline volcanics; 3. Early Eocene: large-scale sedimentary melange (olistostrome) emplacement; 4. Late Eocene-Late Miocene: terrigenous gravity-flow deposition in a deep-water fault dissected 'fore arc' setting. Initial, Late Eocene non-marine coarse clastic alluvial fan deposition was succeeded by Oligocene-Miocene deep-marine siliciclastic gravity flow deposits, fining and shallowing upwards during the Late Miocene; 5. Messinian: localised precipitation of evaporites in small fault-controlled basins; 6. Pliocene: shallow-marine siliciclastic-carbonate deposition in a shelf-depth, overall regressive setting; 7. Latest Pliocene to mid-Pleistocene: gravitational accumulation of coarse talus along a strongly uplifting

  20. Lithostratigraphy of Upper Devonian Scherr-Foreknobs and Lockhaven Formations near Allegheny front of central Pennsylvanian

    SciTech Connect

    Warne, A.G.; McGhee, G.R. Jr.

    1986-05-01

    Five well-exposed sections (at Madley, New Baltimore, Altoona, Milesburg, and Lockhaven) of Upper Devonian marine strata were measured and analyzed to refine lithologic and temporal correlations along the Allegheny Front of Pennsylvania. The members of the Scherr and Foreknobs formations (Minnehaha Springs, Mallow, Briery Gap, Blizzard, Pound, and Red Lock) are recognized as far north as Altoona. Farther north at Milesburg and Lockhaven, the lithology of the upper parts of the Lockhaven Formation are markedly different from the contiguous Foreknobs Formation, but the Minnehaha Springs member of the basal Scherr and lower-middle Lockhaven Formations is recognized in all sections studied. The Minnehaha Springs member (a 50 to 100-ft, resistant, medium-gray to red-gray sandy silt unit) is considered to be the result of a brief sea level lowering and is therefore nearly isochronous. The isochronous nature of the Minnehaha Springs member is substantiated by biostratigraphic data; therefore, it is considered the most reliable datum for correlating the sections of this study. The lithologic information of the six measured sections was augmented by 38 wells logs of oil and gas wells of the region. From the combined lithologic data, three generalized lithofacies cross sections were generated. These cross sections clearly indicate that: (1) the strike of the paleoshoreline was nearly parallel with the Allegheny Front; (2) a major delta lobe existed in central Pennsylvania during the Late Devonian; but (3) the size and influence of the delta on depositional environments was not constant through space and time.

  1. Lower Cretaceous Puez key-section in the Dolomites - towards the mid-Cretaceous super-greenhouse

    NASA Astrophysics Data System (ADS)

    Lukeneder, A.; Halásová, E.; Rehákova, D.; Józsa, Š.; Soták, J.; Kroh, A.; Jovane, L.; Florindo, F.; Sprovieri, M.; Giorgioni, M.; Lukeneder, S.

    2012-04-01

    dtirol' in Bozen, Southern Tyrol. Producing major results with a broad impact requires using tools such as facies analysis supported by lithological, sedimentological and chemical characteristics, isotope and magnetic properties as well as fossil record (ammonites, belemnites, brachiopods, echinoids, planktonic foraminiferas, radiolarians, nannofossils, calcareous dinoflagellates, calpionellids). Foraminiferal study provides the zonal subdivision of the Puez section from Valanginian - Hauterivian gorbachikellids and praehedbergelids (Hedbergella semielongata Zone), Barremo-Aptian praehedbergelids (Blesusciana kuznetzove Zone), Aptian hedbergellids of occulta - aptiana - praetrocoidea group, Early Late Aptian pseudo-planispiral foraminifera (Praehedbergella luterbacheri and Globigerinelloides ferreolensis Zones), important marker species of Hedbergella trocoidea and Paraticinella bejaaouaensis for the Late Aptian zone, Early Albian microperforate hedbergellids (Hedbergella planispira Zone), Mid Albian ticinellids (Ticinella primula Zone), advanced ticinellids like Ticinella roberti etc. (Biticinella breggiensis Zone), Latest Albian rotalliporids (Rotalipora appeninica Zone) up to Early Cenonanian appearance of Thalmanninella (Rotalipora) globotruncanoides. Results of this integrated study will be used for both, the precise biostratigraphy of the sequence studied as well as for the paleoenvironmental reconstruction. Lukeneder A. 2012. New biostratigraphic data on an Upper Hauterivian-Upper Barremian ammonite assemblage from the Dolomites (Southern Alps, Italy). Cretaceous Research. doi:10.1016/j.cretres.2011.11.002 Lukeneder A. 2011. The Biancone and Rosso Ammonitico facies of the northern Trento Plateau (Dolomites, Southern Alps; Italy). Annalen des Naturhistorischen Museum Wien, Serie A, 112, 9-33. Lukeneder A. 2010. Lithostratigraphic definition and stratotype for the Puez Formation: formalisation of the Lower Cretaceous in the Dolomites (S. Tyrol, Italy). Austrian Journals

  2. Advances in ammonite biostratigraphy of the marine Atacama basin (Lower Cretaceous), northern Chile, and its relationship with the Neuquén basin, Argentina

    NASA Astrophysics Data System (ADS)

    Mourgues, Francisco Amaro

    2004-09-01

    Preliminary results about the Lower Cretaceous ammonite biostratigraphy of northern Chile reveal eight fossiliferous levels: Lower-Upper Valanginian neocomitid and olcostephanid faunas in the Punta del Cobre and Abundancia Formations and Upper Hauterivian-Barremian crioceratid in the Nantoco, Totoralillo, and Pabellón Formations. The faunal affinities with the Neuquén are strong during the Valanginian and Hauterivian. In contrast, during the Barremian and Aptian, the ammonites show affinities with Austral, California, and Tethys basinal faunas. The Lower Valanginian-lower Upper Aptian series in northern Chile comprises two sedimentary cycles separated by a regressive pulse of Upper Hauterivian-Lower Barremian age. This pulse may be equivalent to the regression that ended the Early Cretaceous marine cycle in central Chile and central west Argentina, where the second marine sedimentary cycle observed in northern Chile is not represented.

  3. Geology of a cretaceous subduction complex, Western Chicagoof Island, Southeastern Alaska

    NASA Astrophysics Data System (ADS)

    Decker, J. E., Jr.

    1981-08-01

    The geology of the Chugach terrane on Chichagof and Baranof Islands in southeastern Alaska is described and mapped in detail. The Goon Dip Greenstone and the Whitestripe Marble are pre-Late Jurassic in age and possibly correlate with Triassic rocks in the Wrangell Mountains. The Kelp Bay Group is a chaotic metasedimentary and metavolcanic terrane correlative with Lower Cretaceous complexes in the Chugach Mountains and adjacent islands. The Ford Arm Formation