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Sample records for argentina middle jurassic

  1. SHRIMP U-Pb zircon geochronology of Mesozoic granitoids from the Bariloche region (Argentina): Implications for the Middle-Late Jurassic evolution of the North Patagonian batholith.

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    Castro, Antonio; Vujovich, Graciela; Fernández, Carlos; Moreno-Ventas, Iñaki; Martino, Roberto; Corretgé, Guillermo; Díaz-Alvarado, Juan; Heredia, Nemesio; Gallastegui, Gloria

    2010-05-01

    A detailed U-Pb geochronological study has been carried out on granitoids of the North Patagonian batholith in the region of Bariloche (Argentina), between 40°30' S and 41°45' S. In this region, the calc-alkaline, subduction-related, granitic bodies of the North Patagonian batholith intruded an Early Jurassic volcano-sedimentary sequence contemporary with the intrusion of the Subcordilleran Patagonian batholith (J1 magmatism), and unconformably overlying a metamorphic Gondwanan basement. All these rocks were affected by the Andean compressional phases during the Cenozoic. U-Pb SHRIMP dating of zircon crystals from 11 samples (109 spots) of diorites, tonalites, granodiorites and granites yielded dates ranging from 173 ± 3 Ma to 150 ± 2 Ma (Aalenian to Tithonian). No significant age differences have been identified among the distinct lithological types. Also no spatial trend emerges from these results, although ages tend to be younger westward in the traverse of the Manso River (≈ 41° 35' S). Two peaks appear in the probability density plot of zircon ages. Most of the dated zircons are Bajocian-Bathonian (Middle Jurassic, ≈169 Ma, J2 magmatism), while a secondary peak is observed at the boundary Oxfordian-Kimmeridgian (Late Jurassic, ≈ 156 Ma, J3 magmatism). The J2 magmatic period is coeval to the main stage of effusive activity (V2) in the huge volcanic Chon Aike Province, while J3 coincides with the lesser V3 period of volcanism in Chon Aike. These new geochronological data strongly contribute to the knowledge of the first stages of tectonic evolution of the Andean subduction margin in southern South America. Contrary to previous models, it can be proposed that the subduction-related Mesozoic magmatism started well before the Late Jurassic, and that a continuous supply of calc-alkaline magmas dominated the active margin of South America during at least 190 Ma, from the Early Jurassic to nowadays. Therefore, no dramatic time gap can be observed between

  2. THE TRIASSIC/JURASSIC BOUNDARY IN THE ANDES OF ARGENTINA

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    ALBERTO C. RICCARDI

    2004-03-01

    Full Text Available The Arroyo Malo Formation at Alumbre Creek, on the northern bank of the Atuel River, west central Argentina, comprises a c. 300 m thick continuous marine succession across the Triassic-Jurassic System boundary, consisting of massive and laminated pelites indicative of a slope depositional environment. Late Triassic invertebrates, including ammonoids, nautiloids, bivalves, gastropods, brachiopods and corals are restricted to the lower 150 m. Beds between 125-135 m from the bottom yield Choristoceras cf. marshi Hauer, a species found in the Marshi/Crickmayi Zone of Europe and North America, together with loose fragments of Psiloceras cf. pressum Hillebrandt, coeval with the lower to middle part of the Hettangian Planorbis Zone. About 80 m higher are beds yielding Psiloceras cf. rectocostatum Hillebrandt, a species that gives name to an Andean biozone partially coeval with the Johnstoni and Plicatulum Subzones, upper Planorbis Zone. Other fossils recorded in the Rhaetian strata of this section are foraminifers, ostracods and plant remains identified as Zuberia cf. zuberi (Szaj. Freng. and Clathropteris sp. The section was also sampled for conodonts and radiolarians, thus far with negative results. A palaeomagnetic study is underway.

  3. Harvestmen (Arachnida: Opiliones) from the Middle Jurassic of China

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    Huang, Diying; Selden, Paul A.; Dunlop, Jason A.

    2009-08-01

    Harvestmen (Arachnida: Opiliones) are familiar animals in most terrestrial habitats but are rare as fossils, with only a handful of species known from each of the Palaeozoic, Mesozoic, and Cenozoic eras. Fossil harvestmen from Middle Jurassic (ca. 165 Ma) strata of Daohugou, Inner Mongolia, China, are described as Mesobunus martensi gen. et sp. nov. and Daohugopilio sheari gen. et sp. nov.; the two genera differ primarily in the relative length of their legs and details of the pedipalps. Jurassic arachnids are extremely rare and these fossils represent the first Jurassic, and only the fourth Mesozoic, record of Opiliones. These remarkably well-preserved and modern-looking fossils are assigned to the Eupnoi, whereby M. martensi demonstrably belongs in Sclerosomatidae. It thus represents the oldest record of a modern harvestman family and implies a high degree of evolutionary stasis among one of the most widespread and abundant groups of long-legged, round-bodied harvestmen.

  4. A Middle Jurassic heterodontosaurid dinosaur from Patagonia and the evolution of heterodontosaurids

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    Pol, Diego; Rauhut, Oliver W. M.; Becerra, Marcos

    2011-05-01

    Heterodontosauridae is a morphologically divergent group of dinosaurs that has recently been interpreted as one of the most basal clades of Ornithischia. Heterodontosaurid remains were previously known from the Early Jurassic of southern Africa, but recent discoveries and studies have significantly increased the geographical and temporal range for this clade. Here, we report a new ornithischian dinosaur from the Middle Jurassic Cañadón Asfalto Formation in central Patagonia, Argentina. This new taxon, Manidens condorensis gen. et sp. nov., includes well-preserved craniomandibular and postcranial remains and represents the only diagnostic ornithischian specimen yet discovered in the Jurassic of South America so far. Derived features of its anatomy indicate that Manidens belongs to Heterodontosauridae, as the sister taxon of Heterodontosaurus and other South African heterodontosaurids. The presence of posterior dentary teeth with high crowns but lacking extensive wear facets in Manidens suggests that this form represents an intermediate stage in the development of the remarkable adaptations to herbivory described for Heterodontosaurus. The dentition of Manidens condorensis also has autapomorphies, such as asymmetrically arranged denticles in posterior teeth and a mesially projected denticle in the posteriormost teeth. At an estimated total length of 60-75 cm, Manidens furthermore confirms the small size of basal heterodontosaurids.

  5. Carbon cycle history through the Middle Jurassic of Hungary

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    Price, Gregory; Fozy, Istvan; Galacz, Andras

    2016-04-01

    A carbonate carbon isotope curve from the Aalenian-Bathonian interval is presented from the Obanya valley, of the Mecsek Mountains, Hungary. This interval is less well constrained and studied that other Jurassic time slices. The Obanya valley lies in the eastern part of the Mecsek Mountains, between Obanya and Kisujbanya and provides excellent exposures of a near continuous Aalenian to Lower Cretaceous sequence. It is not strongly affected by tectonics, as compared to other sections of eastern Mecsek of the same age. In parts, a rich fossil assemblage has been collected; the Bathonian ammonites are especially valuable as this locality. The pelagic Middle Jurassic is represented by thin-bedded limestones (the Obanya Limestone) and is overlain by Upper Jurassic siliceous limestones and radiolarites (the Fonyaszo Limestone). The new data indicates a series of positive anomalies within the late Aalenian and early-middle Bajocian. These data are comparable with carbonate carbon isotope recorded from other Tethyan margin sediments. Our integrated biostratigraphy and carbon isotope stratigraphy enables us to improve stratigraphic correlation and age determination of the examined strata.

  6. Jurassic Paleoclimates in Argentina, a review Paleoclimas jurásicos en la Argentina, una revisión

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    Wolfgang Volkheimer

    2008-12-01

    Full Text Available New paleoclimatic evidence from palynologic and vertebrate proxies provides more detailed data on climatic change during the Jurassic in Argentina. Comparison with paleomagnetic data shows that the Neuquén basin shifted from the highest paleolatitudes (50ºS, by the end of the Triassic until the end of the Sinemurian. During the Pliensbachian-Toarcian it moved northward, reaching the lowermost paleolatitudes (25ºS, and subsequently (Middle to Late Jurassic the area moved again and attained eventually a position similar to its present-day position (30ºS. These movements are reflected in the Jurassic palynofloras. The high frequency of the pollen genus Classopollis (Cheirolepidiacean gymnosperms is of special paleoclimatic importance in the Argentinian Jurassic, as it is indicative of seasonal aridity or semiarid conditions during large intervals of this Period. During the shift of the South American continent to the northernmost position, the arrival of an important group of Araucariaceae, represented by Callialasporites spp., in the Toarcian could indicate an amelioration related to more humid conditions. Jurassic dinocyst assemblages studied in the Neuquén basin have proved to be useful paleoclimatic and paleobiogeographic proxies. Abundant remains of marine crocodiles in the Mid- and Late Jurassic of the Neuquén basin indicate warm water temperatures for this basin, probably in excess of 20° C. The occurrence of abundant turtles and other ectothermic vertebrates in the Middle Jurassic Cañadón Asfalto Formation of Chubut is in general accordance with the warm climate indicated for this unit by geologic evidence.Nuevas evidencias de indicadores paleoclimáticos (palinológicos y de vertebrados suministran datos detallados sobre los cambios climáticos en el Jurásico de la Argentina. La comparación con datos paleomagnéticos muestra como, desde fines del Triásico hasta el Sinemuriano Tardío, la cuenca Neuquina derivó ocupando las

  7. A New Theropod Dinosaur from the Middle Jurassic of Lufeng, Yunnan, China

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    WU Xiao-chun; Philip J.CURRIE; DONG Zhiming; PAN Shigang; WANG Tao

    2009-01-01

    A new theropod dinosaur,Shidaisaurusjinae gen.et sp.nov.,has been described on the basis of an incomplete skeleton.The specimen was found near the base of the Upper Lufeng Formation(early Middle Jurassic)in Yunnan,China.It is the first theropod dinosaur from the Middle Jurassic of Yunnan.Shidaisaurus jinae is distinguishable from other Jurassic theropods by certain features from the braincase,axis,and pelvic girdle.The absence of any pleurocoels in the axis or in any anterior dorsal vertebrae suggests that the new Lufeng theropod is relatively primitive and more plesiomorphic than most of the Middle to Late Jurassic theropods from China.Most Chinese taxa of Jurassic theropod dinosaurs have not been well described;a further detailed study will be necessary for us to determine their phylogenetic relationships with Shidaisaurus jinae.

  8. New fossil record of a Jurassic pterosaur from Neuquen Basin, Vaca Muerta Formation, Argentina

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    Codorniú, Laura; Garrido, Alberto

    2013-12-01

    Discoveries of Jurassic pterosaurs in the Southern Hemisphere are extremely unusual. In Argentina, pterosaurs from the Upper Jurassic (Tithonian) have only been found in the Northwest of Patagonia (Neuquén Basin). These come from marine deposits and three specimens have been discovered up to the present. In this paper, we report a new finding from the Neuquén Basin. This material is identified as a tibiotarsus, which probably belonged to an osteologically adult individual and represents a new species of a pterodactyloid pterosaur of medium size. This discovery provides new evidence that at least two different species of pterodactyloid pterosaurs may have coexisted in Los Catutos Member, Vaca Muerta Formation, from the shallow marine deposits of the Neuquén Basin.

  9. Transgression regression event element geochemistry records of southwestern Fujian in Late Triassic-Middle Jurassic

    Institute of Scientific and Technical Information of China (English)

    许中杰; 程日辉; 张莉; 王嘹亮

    2013-01-01

    Southwest Fujian area has experienced a large-scale transgression regression cycle in Late Triassic-Middle Jurassic and the maximum transgression has taken place in Early Jurassic. The migration and enrichment of geochemical element in the continuous fine-grained sediments in the basin recorded the paleosalinity and the paleodepth. The changes of paleosalinity and paleodepth indicate the sea(lake) level relative change in every period of Late Triassic-Middle Jurassic in southwestern Fujian. The relative change curve of sea(lake) level in southwestern Fujian is established based on the m value(m=100×w(MgO)/w(Al2 O3)) and the ratios of w(B)/w(Ga), w(Sr)/w(Ba) and w(Ca)/w(Mg). The curve indicates that level I sea-level relative change in southwestern Fujian is composed of the transgression in Late Triassic-Early Jurassic and the regression in the late period of Early Jurassic-Middle Jurassic. The level III sea-level relative change is frequent, which is composed by the lake level descent lake level rise lake level descent of Wenbin Shan formation in Late Triassic, the regression transgression regression of Lishan formation in Early Jurassic and the lake level rise lake level descent-lake level rise lake level descent of Zhangping formation in Middle Jurassic. The transgression regression cycle in southwestern Fujian is significantly controlled by the sea-level change in the north of South China Sea. The relative change curve trends of the level I sea-level in the north of South China Sea and the one in southwestern Fujian are the same. The maximum transgressions both occur in Early Jurassic. The level III sea-level curve reflects the fluctuation of a transgression and two regressions in the early period of Early Jurassic.

  10. Two new species of Paramesosciophilodes (Diptera, Nematocera, Mesosciophilidae from the Middle Jurassic of China

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    Jiaqi Gao

    2015-07-01

    Full Text Available Two new species, Paramesosciophilodes bellus sp. n. and Paramesosciophilodes rarissima sp. n., from the Jiulongshan Formation at Daohugou Village, Inner Mongolia, China, are described in the extinct family Mesosciophilidae. Altogether seven genera with 21 species of mesosciophilids have been described from the Jurassic of Siberia and Kazakhstan, the Lower Cretaceous of Transbaikalia, and the Middle Jurassic of Inner Mongolia. An emended generic diagnosis of Paramesosciophilodes and a list of known taxa of mesosciophilids are provided.

  11. Two new species of Paramesosciophilodes (Diptera, Nematocera, Mesosciophilidae) from the Middle Jurassic of China.

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    Gao, Jiaqi; Shi, Guifeng; Shih, Chungkun; Ren, Dong

    2015-01-01

    Two new species, Paramesosciophilodesbellus sp. n. and Paramesosciophilodesrarissima sp. n., from the Jiulongshan Formation at Daohugou Village, Inner Mongolia, China, are described in the extinct family Mesosciophilidae. Altogether seven genera with 21 species of mesosciophilids have been described from the Jurassic of Siberia and Kazakhstan, the Lower Cretaceous of Transbaikalia, and the Middle Jurassic of Inner Mongolia. An emended generic diagnosis of Paramesosciophilodes and a list of known taxa of mesosciophilids are provided.

  12. The first euthemistid damsel-dragonfly from the Middle Jurassic of China (Odonata, Epiproctophora, Isophlebioptera

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    Yongjun Li

    2013-01-01

    Full Text Available Sinoeuthemis daohugouensis gen. et sp. n. is the first record of the isophlebiopteran family Euthemistidae from Middle Jurassic of northeast China, while previously this family was restricted to the early Late Jurassic Kazakhstan. This new finding allows us to emend the family diagnosis with hindwing characters. This new species shows a mixture of characters alternatively present in different genera of the two families Euthemistidae and Sphenophlebiidae.

  13. In situ Gymnosperm pollen from the Middle Jurassic of Yorkshire

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    Konijnenburg-van Cittert, van Johanna H.A.

    1971-01-01

    In this paper the morphology of pollen grains yielded by male Gymnosperm fructifications from the Jurassic flora of Yorkshire is studied and discussed. Several new male fructifications were found and described: Hastystrobus gen. nov. was erected for male cones yielding the Eucommiidites type of poll

  14. Early and Middle Jurassic climate changes: implications for palaeoceanography and tectonics

    DEFF Research Database (Denmark)

    Korte, Christoph; Hesselbo, Stephen; Ullmann, Clemens Vinzenz;

    2014-01-01

    three pronounced oxygen isotope ‘Ice Age’ cycles, and the subsequent well known Toarcian Oceanic Anoxic ‘supergreenhouse’ Event is followed by very warm seawater temperatures in the late Toarcian. Moreover, a very pronounced and effective cooling occurred during the latest Toarcian and early Aalenian...... (Early-Middle Jurassic Boundary Event) resulted in substantial expansion of Arctic climates to palaeolatitudes as low as 45° and in distinctly cooler seawater temperatures in lower latitude European seas. At least the extensive cooling at the Early-Middle Jurassic Boundary Event was most likely driven...

  15. A New Basal Sauropod Dinosaur from the Middle Jurassic of Niger and the Early Evolution of Sauropoda

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    Remes, Kristian; Ortega, Francisco; Fierro, Ignacio; Joger, Ulrich; Kosma, Ralf; Marín Ferrer, José Manuel; Ide, Oumarou Amadou; Maga, Abdoulaye

    2009-01-01

    Background The early evolution of sauropod dinosaurs is poorly understood because of a highly incomplete fossil record. New discoveries of Early and Middle Jurassic sauropods have a great potential to lead to a better understanding of early sauropod evolution and to reevaluate the patterns of sauropod diversification. Principal Findings A new sauropod from the Middle Jurassic of Niger, Spinophorosaurus nigerensis n. gen. et sp., is the most complete basal sauropod currently known. The taxon shares many anatomical characters with Middle Jurassic East Asian sauropods, while it is strongly dissimilar to Lower and Middle Jurassic South American and Indian forms. A possible explanation for this pattern is a separation of Laurasian and South Gondwanan Middle Jurassic sauropod faunas by geographic barriers. Integration of phylogenetic analyses and paleogeographic data reveals congruence between early sauropod evolution and hypotheses about Jurassic paleoclimate and phytogeography. Conclusions Spinophorosaurus demonstrates that many putatively derived characters of Middle Jurassic East Asian sauropods are plesiomorphic for eusauropods, while South Gondwanan eusauropods may represent a specialized line. The anatomy of Spinophorosaurus indicates that key innovations in Jurassic sauropod evolution might have taken place in North Africa, an area close to the equator with summer-wet climate at that time. Jurassic climatic zones and phytogeography possibly controlled early sauropod diversification. PMID:19756139

  16. A new basal sauropod dinosaur from the middle Jurassic of Niger and the early evolution of sauropoda.

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    Kristian Remes

    Full Text Available BACKGROUND: The early evolution of sauropod dinosaurs is poorly understood because of a highly incomplete fossil record. New discoveries of Early and Middle Jurassic sauropods have a great potential to lead to a better understanding of early sauropod evolution and to reevaluate the patterns of sauropod diversification. PRINCIPAL FINDINGS: A new sauropod from the Middle Jurassic of Niger, Spinophorosaurus nigerensis n. gen. et sp., is the most complete basal sauropod currently known. The taxon shares many anatomical characters with Middle Jurassic East Asian sauropods, while it is strongly dissimilar to Lower and Middle Jurassic South American and Indian forms. A possible explanation for this pattern is a separation of Laurasian and South Gondwanan Middle Jurassic sauropod faunas by geographic barriers. Integration of phylogenetic analyses and paleogeographic data reveals congruence between early sauropod evolution and hypotheses about Jurassic paleoclimate and phytogeography. CONCLUSIONS: Spinophorosaurus demonstrates that many putatively derived characters of Middle Jurassic East Asian sauropods are plesiomorphic for eusauropods, while South Gondwanan eusauropods may represent a specialized line. The anatomy of Spinophorosaurus indicates that key innovations in Jurassic sauropod evolution might have taken place in North Africa, an area close to the equator with summer-wet climate at that time. Jurassic climatic zones and phytogeography possibly controlled early sauropod diversification.

  17. MIDDLE TO LATE JURASSIC BIOFACIES OF SAUDI ARABIA

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    GERAINT W. HUGHES

    2004-03-01

    Full Text Available Saudi Arabian Jurassic carbonate hydrocarbon reservoirs were first examined stratigraphically using microfauna. Current microfaunal studies concentrate on the identification and constraint of palaeoenvironmental variations and determination of high-resolution depositional cyclicity of the reservoir carbonates. It is apparent that the environmental sensitivity of benthonic foraminifera provides a potentially valuable technique for the determining subtle variations in the depositional environment and also providing a proxy for sea-level fluctuations.

  18. New Isophlebioid Dragonflies from the Middle Jurassic of Inner Mongolia, China (Insecta: Odonata: Isophlebioptera:Campterophlebiidae)

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    ZHANG Binglan; REN Dong; PANG Hong

    2008-01-01

    Three new species of fossil dragonflies assigned to Sinokaratawia Nel, Huang and Lin in family Campterophlebiidae, i.e. S. daohugouica sp. nov., S. magica sp. nov. and S. gloriosa sp. nov., and new materials of male S. prokopi Nel, Huang and Lin, 2007 are described from the Middle Jurassic of Daohugou, Inner Mongolia, China. An emended diagnosis of genus Sinokaratawia was proposed.

  19. Geomagnetic field intensity in the middle jurassic - oligocene

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    Kurazhkovskii, A Yu; Klain, B I

    2014-01-01

    The present paper summarizes results of the studies on the intensity of geomagnetic field in the (167 - 23) Ma interval by sedimentary rocks of the Russian Plate and adjacent territories. The joint analysis of the data paleointensity obtained by sedimentary and thermomagnetized (from PINT12) rocks within this temporal interval is conducted. It is shown that the changes of the paleointensity were occurred chaotically. Alternating bursts and periods of quiet regime of the geomagnetic field are typical for intermittent processes and is a characteristic of the geological interval Jurassic-beginning of Paleogene. The distributions of the paleointensity corresponding to different intervals of geologic time were investigated. It is revealed that the cumulative distribution function (CDF) of the paleointensity values is best approximated by a power function. The indices of the power functions varied depending on geologic time intervals.The analysis of the paleomagnetic data suggests that the medium in which the geoma...

  20. The Jurassic of Denmark and Greenland: The Middle Jurassic of western and northern Europe: its subdivisions, geochronology and correlations

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    Callomon, John H.

    2003-10-01

    Full Text Available The palaeogeographic settings of Denmark and East Greenland during the Middle Jurassic are outlined. They lay in the widespread epicontinental seas that covered much of Europe in the post-Triassic transgression. It was a period of continuing eustatic sea-level rise, with only distant connections to world oceans: to the Pacific, via the narrow Viking Straits between Greenland and Norway and hence the arctic Boreal Sea to the north; and to the subtropical Tethys, via some 1200 km of shelf-seas to the south. The sedimentary history of the region was strongly influenced by two factors: tectonism and climate. Two modes of tectonic movement governed basinal evolution: crustal extension leading to subsidence through rifting, such as in the Viking and Central Grabens of the North Sea; and subcrustal thermal upwelling, leading to domal uplift and the partition of marine basins through emergent physical barriers, as exemplified by the Central North Sea Dome with its associated volcanics. The climatic gradient across the 30º of temperate latitude spanned by the European seas governed biotic diversity and biogeography, finding expression in rock-forming biogenic carbonates that dominate sediments in the south and give way to largely siliciclastic sediments in the north. Geochronology of unrivalled finesse is provided by standard chronostratigraphy based on the biostratigraphy of ammonites. The Middle Jurassic saw the onset of considerable bioprovincial endemisms in these guide-fossils, making it necessary to construct parallel standard zonations for Boreal, Subboreal or NW European and Submediterranean Provinces, of which the NW European zonation provides the primary international standard. The current versions of these zonations are presented and reviewed.

  1. Three new species of mesosciophilid gnats from the Middle-Late Jurassic of China (insecta: Diptera: Nematocera: Mesosciophilidae).

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    Zhang, J F

    2008-11-15

    Three extinct new species from the Callovian or Oxfordian (uppermost Middle Jurassic or lowermost Upper Jurassic) Daohugou beds in Inner Mongolia, China is described as Mesosciophila abstracta sp. n., Mesosciophilodes synchrona sp. n. and Paramesosciophilodes eximia sp. n. (Family Mesosciophilidae). All the records of mesosciophilid gnats are briefly reviewed.

  2. Jurassic fishes of Gondwana

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    Adriana López-Arbarello

    2008-12-01

    Full Text Available The Jurassic is an important period for understanding the origin of modern fish faunas, since it saw the first radiation - and in some cases the origin - of most modern groups. In chondrichthyans, neoselachian sharks and rays diversified during this time. In actinopterygians, the neopterygians, and among them the teleosts, experienced an important radiation, which led to the appearance of several of the modern teleosts groups. In the sarcopterygians, dipnoans and actinistians approached their current forms. However, the Jurassic fossil record of fishes is strongly biased towards the Northern Hemisphere. The only notable Early Jurassic fish fauna from Gondwana is that of the Kota Formation of India. For the Middle Jurassic, the most important Gondwanan fish faunas are those of the Aalenian-Bathonian Stanleyville Beds of the Democratic Republic of Congo, in which a distinct freshwater and a marine fauna are found. In the Late Jurassic, the Gondwanan record is slightly better, with important marine faunas being known from the Oxfordian Quebrada del Profeta in Chile and the Tithonian Vaca Muerta Formation of Argentina. Freshwater faunas have been described from the Tithonian Talbragar Beds of eastern Australia and the Tithonian Cañadón Calcáreo Formation of Argentina. The taxonomic composition of the known marine actinopterygian faunas of Gondwana is in general agreement with faunas of the Northern Hemisphere. However, the Jurassic fish record from Gondwana is highly incomplete both stratigraphically and geographically, and most faunas are in need of revision, further hampering an interpretation of Jurassic fish evolution in the Southern Hemisphere.

  3. Ichnological evidence of Megalosaurid Dinosaurs Crossing Middle Jurassic Tidal Flats.

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    Razzolini, Novella L; Oms, Oriol; Castanera, Diego; Vila, Bernat; Santos, Vanda Faria Dos; Galobart, Àngel

    2016-08-19

    A new dinosaur tracksite in the Vale de Meios quarry (Serra de Aire Formation, Bathonian, Portugal)preserves more than 700 theropod tracks. They are organized in at least 80 unidirectional trackways arranged in a bimodal orientation pattern (W/NW and E/SE). Quantitative and qualitative comparisons reveal that the large tridactyl, elongated and asymmetric tracks resemble the typical Late Jurassic-Early Cretaceous Megalosauripus ichnogenus in all morphometric parameters. Few of the numerous tracks are preserved as elite tracks while the rest are preserved as different gradients of modified true tracks according to water content, erosive factors, radial fractures and internal overtrack formations. Taphonomical determinations are consistent with paleoenvironmental observations that indicate an inter-tidal flat located at the margin of a coastal barrier. The Megalosauripus tracks represent the oldest occurrence of this ichnotaxon and are attributed to large megalosaurid dinosaurs. Their occurrence in Vale de Meios tidal flat represents the unique paleoethological evidence of megalosaurids moving towards the lagoon, most likley during the low tide periods with feeding purposes.

  4. Ichnological evidence of Megalosaurid Dinosaurs Crossing Middle Jurassic Tidal Flats

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    Razzolini, Novella L.; Oms, Oriol; Castanera, Diego; Vila, Bernat; Santos, Vanda Faria Dos; Galobart, Àngel

    2016-08-01

    A new dinosaur tracksite in the Vale de Meios quarry (Serra de Aire Formation, Bathonian, Portugal)preserves more than 700 theropod tracks. They are organized in at least 80 unidirectional trackways arranged in a bimodal orientation pattern (W/NW and E/SE). Quantitative and qualitative comparisons reveal that the large tridactyl, elongated and asymmetric tracks resemble the typical Late Jurassic-Early Cretaceous Megalosauripus ichnogenus in all morphometric parameters. Few of the numerous tracks are preserved as elite tracks while the rest are preserved as different gradients of modified true tracks according to water content, erosive factors, radial fractures and internal overtrack formations. Taphonomical determinations are consistent with paleoenvironmental observations that indicate an inter-tidal flat located at the margin of a coastal barrier. The Megalosauripus tracks represent the oldest occurrence of this ichnotaxon and are attributed to large megalosaurid dinosaurs. Their occurrence in Vale de Meios tidal flat represents the unique paleoethological evidence of megalosaurids moving towards the lagoon, most likley during the low tide periods with feeding purposes.

  5. A previously unrecognized group of Middle Jurassic triconodontan mammals from Central Asia

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    Martin, Thomas; Averianov, Alexander O.

    2007-01-01

    Ferganodon narynensis gen. et sp. nov. is represented by a lower molariform tooth from the Middle Jurassic (Callovian) Balabansai Svita in Kyrgyzstan. The new genus is allied with Klamelia zhaopengi Chow and Rich 1984 from the Middle Jurassic Shishugou Formation in Xinjiang, northwest China to the new family Klameliidae based on parallelogram-shaped lower molariforms, imbricating rather than interlocking of cusps e- d- f, by a peculiar distolabial cingulid cusp, and by vertical folding of the enamel on the labial crown side. The new family Klameliidae fam. nov. is most similar to Gobiconodontidae by the structure of the molariform teeth and represents a previously unrecognized radiation of eutriconodontan mammals possibly endemic to Central Asia.

  6. The oldest haplogyne spider (Araneae: Plectreuridae), from the Middle Jurassic of China

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    Selden, Paul A.; Huang, Diying

    2010-05-01

    New fossil spiders (Arachnida: Araneae) from Middle Jurassic (ca. 165 Ma) strata of Daohugou, Inner Mongolia, China are described as Eoplectreurys gertschi gen. et sp. nov. and referred to the modern haplogyne family Plectreuridae. This small family is restricted to southwestern USA, Mexico, and the adjacent Caribbean area today and hitherto has only a sparse Cenozoic fossil record. The morphology of Eoplectreurys is remarkably similar to modern forms and thus demonstrates great evolutionary conservatism. This new discovery not only extends the fossil record of the family by at least 120 Ma to the Middle Jurassic but also supports the hypothesis of a different distribution of the family in the past than today and subsequent extinction over much of its former range.

  7. A golden orb-weaver spider (Araneae: Nephilidae: Nephila) from the Middle Jurassic of China

    OpenAIRE

    Paul A Selden; Shih, Chungkun; Ren, Dong

    2011-01-01

    Nephila are large, conspicuous weavers of orb webs composed of golden silk, in tropical and subtropical regions. Nephilids have a sparse fossil record, the oldest described hitherto being Cretaraneus vilaltae from the Cretaceous of Spain. Five species from Neogene Dominican amber and one from the Eocene of Florissant, CO, USA, have been referred to the extant genus Nephila. Here, we report the largest known fossil spider, Nephila jurassica sp. nov., from Middle Jurassic (approx. 165 Ma) strat...

  8. Bajocian-Bathonian (Middle Jurassic) sea-level changes in northeastern Egypt: Synthesis and further implications

    Science.gov (United States)

    Ruban, Dmitry A.; Sallam, Emad S.

    2016-08-01

    The global eustatic developments can benefit significantly from properly acquired regional information. Summarizing the available interpretations of the relative sea-level changes from two areas in northeastern Egypt, namely Gebel Maghara and Khashm El-Galala, allows better understanding of the Middle Jurassic sea-level changes. It is established that the Bajocian-Bathonian relative sea-level changes in these areas were coherent. The magnitude of changes was lower in the Bajocian than in the Bathonian. Significant sea-level rises occurred at the Bajocian-Bathonian and middle-late Bathonian transitions, and there was a clear tendency toward sea-level rise throughout the studied time interval. This evidence favors one of the two alternative global eustatic reconstructions that implies "stable" position of the shoreline in the Bajocian and general tendency to eustatic rise throughout the Jurassic. The tectonic regime of northeastern Egypt in the Middle Jurassic provided for strong eustatic control of the relative sea-level changes. The possible influence of hotspot activity is questionable. Filling the accommodation space with materials derived from the eroded continent may explain some sea-level falls that are regionally documented.

  9. Middle Jurassic Topawa group, Baboquivari Mountains, south-central Arizona: Volcanic and sedimentary record of deep basins within the Jurassic magmatic arc

    Science.gov (United States)

    Haxel, G.B.; Wright, J.E.; Riggs, N.R.; Tosdal, R.M.; May, D.J.

    2005-01-01

    Among supracrustal sequences of the Jurassic magmatic arc of the southwestern Cordillera, the Middle Jurassic Topawa Group, Baboquivari Mountains, south-central Arizona, is remarkable for its lithologic diversity and substantial stratigraphic thickness, ???8 km. The Topawa Group comprises four units (in order of decreasing age): (1) Ali Molina Formation-largely pyroclastic rhyolite with interlayered eolian and fluvial arenite, and overlying conglomerate and sandstone; (2) Pitoikam Formation-conglomerate, sedimentary breccia, and sandstone overlain by interbedded silt- stone and sandstone; (3) Mulberry Wash Formation-rhyolite lava flows, flow breccias, and mass-flow breccias, with intercalated intraformational conglomerate, sedimentary breccia, and sandstone, plus sparse within-plate alkali basalt and comendite in the upper part; and (4) Tinaja Spring Porphyry-intrusive rhyolite. The Mulberry Wash alkali basalt and comendite are genetically unrelated to the dominant calcalkaline rhyolite. U-Pb isotopic analyses of zircon from volcanic and intrusive rocks indicate the Topawa Group, despite its considerable thickness, represents only several million years of Middle Jurassic time, between approximately 170 and 165 Ma. Sedimentary rocks of the Topawa Group record mixing of detritus from a minimum of three sources: a dominant local source of porphyritic silicic volcanic and subvolcanic rocks, identical or similar to those of the Topawa Group itself; Meso- proterozoic or Cambrian conglomerates in central or southeast Arizona, which contributed well-rounded, highly durable, polycyclic quartzite pebbles; and eolian sand fields, related to Middle Jurassic ergs that lay to the north of the magmatic arc and are now preserved on the Colorado Plateau. As the Topawa Group evidently represents only a relatively short interval of time, it does not record long-term evolution of the Jurassic magmatic arc, but rather represents a Middle Jurassic "stratigraphic snapshot" of the arc

  10. The oldest known snakes from the Middle Jurassic-Lower Cretaceous provide insights on snake evolution.

    Science.gov (United States)

    Caldwell, Michael W; Nydam, Randall L; Palci, Alessandro; Apesteguía, Sebastián

    2015-01-27

    The previous oldest known fossil snakes date from ~100 million year old sediments (Upper Cretaceous) and are both morphologically and phylogenetically diverse, indicating that snakes underwent a much earlier origin and adaptive radiation. We report here on snake fossils that extend the record backwards in time by an additional ~70 million years (Middle Jurassic-Lower Cretaceous). These ancient snakes share features with fossil and modern snakes (for example, recurved teeth with labial and lingual carinae, long toothed suborbital ramus of maxillae) and with lizards (for example, pronounced subdental shelf/gutter). The paleobiogeography of these early snakes is diverse and complex, suggesting that snakes had undergone habitat differentiation and geographic radiation by the mid-Jurassic. Phylogenetic analysis of squamates recovers these early snakes in a basal polytomy with other fossil and modern snakes, where Najash rionegrina is sister to this clade. Ingroup analysis finds them in a basal position to all other snakes including Najash.

  11. Paleogeography of the northern portion of the Mixteca terrain, southern Mexico, during the Middle Jurassic

    Science.gov (United States)

    Caballero-Miranda, C.; Morán-Zenteno, D. J.; Urrutia-Fucugauchi, J.; Silva-Romo, G.; Böhnel, H.; Jurado-Chichay, Z.; Cabral-Cano, E.

    A preliminary paleogeographic reconstruction of the northern Mixteca terrain in southern Mexico is presented for the Middle Jurassic. The reconstruction is derived from combined analyses of spatial distribution of marine-continental Jurassic sedimentary units, identification of sediment source, and observations based on sedimentary indicators of environment and transport directions, as well as paleomagnetic and anisotropy of magnetic susceptibility (AMS) results. There is an overall agreement between the AMS magnetic fabric results and the sedimentary indicators of current directions and paleogeographic elements. The results suggest a coastline at the south-southwest portion of this terrain, a general transport of fluvial sediments to the south and southwest, and marine influxes from the south. A Pacific margin provenance is supported by the paleomagnetic results for the northern portion of the Mixteca terrain.

  12. MIDDLE JURASSIC-LOWER CRETACEOUS BIOSTRATIGRAPHY IN THE CENTRAL PONTIDES (TURKEY): REMARKS ON PALEOGEOGRAPHY AND TECTONIC EVOLUTION

    OpenAIRE

    BORA ROJAY; DEMIR ALTINER

    1998-01-01

    The deposition of Jurassic-Lower Cretaceous carbonates in the Pontides was controlled mainly by the evolution of an Atlantic-type continental margin in the Tethys. The study of several stratigraphic sections from allochthonous slices and blocks of the North Anatolian Ophiolitic Melange provided insight into the Middle Jurassic-Early Cretaceous paleogeographic evolution of the Central Pontide Belt. The Callovian-Aptian successions span the Globuligerina gr. oxfordiana, Clypeina jurassica (equi...

  13. The first euthemistid damsel-dragonfly from the Middle Jurassic of China (Odonata, Epiproctophora, Isophlebioptera).

    Science.gov (United States)

    Li, Yongjun; Nel, André; Shih, Chungkun; Ren, Dong; Pang, Hong

    2013-01-01

    Sinoeuthemis daohugouensis gen. et sp. n. is the first record of the isophlebiopteran family Euthemistidae from Middle Jurassic of northeast China, while previously this family was restricted to the early Late Jurassic Kazakhstan. This new finding allows us to emend the family diagnosis with hindwing characters. This new species shows a mixture of characters alternatively present in different genera of the two families Euthemistidae and Sphenophlebiidae.

  14. New fossil elaterids (Insect: Coleoptera: Polyphaga: Elateridae) from the Middle Jurassic of Inner Mongolia, China

    Institute of Scientific and Technical Information of China (English)

    Huali Chang; Yunyun Zhao; Dong Ren

    2009-01-01

    A new genus with a new species of fossil elaterid, Paraprotagrypnus superbus gen. et sp. nov., from the Middle Jurassic Jiulongshan Formation in Daohugou Village (N41°18.979', E119°14.318'), Shantou Township, Ningcheng County, Inner Mongolia, China is described and illustrated. The genus Paraprotagrypnus belongs to the family of Elateridae, subfamily of Protagrypninae and tribe of Protagrypnini. Some primitive characters of the new genus and new species shed light on the ages between the Jiulongshan Formation in Inner Mongolia and the Yixian Formation in the western Liaoning Province of China. The habitat of the new species is briefly discussed.

  15. New fossil caddisfly from Middle Jurassic of Daohugou, Inner Mongolia, China (Trichoptera: Philopotamidae)

    Institute of Scientific and Technical Information of China (English)

    Meixia Wang; Yunyun Zhao; Dong Ren

    2009-01-01

    A new genus and new species, Juraphilopotamus lubricus gen. et sp. nov., from the Middle Jurassic Jiulongshan Formation of Daohugou, Inner Mongolia, China, is described and illustrated. It may be the first record of the family Philopotamidae in China, extending the geographic distribution of this family. A detailed description and illustration of the specimen along with a brief review of the fossil Philopotamidae are given. A proposal on dispersion and migration of Philopotamidae and problems of the paleoenvironment of the Daohugou beds are discussed.

  16. New Fossils of Eoptychopteridae (Diptera)from the Middle Jurassic of Northeastern China

    Institute of Scientific and Technical Information of China (English)

    HAO Jianying; REN Dong; SHIH Chungkun

    2009-01-01

    Three new species of the extinct genus of Eoptychopterina from the Eoptychopteridae family, Eoptychopterina antica sp. nov., Eoptychopterina adnexa sp. nov., and Eoptychopterina mediata sp. nov., are described and illustrated. These three new species are established based on fossil specimens with bodies and complete wings. All were collected from the Middle Jurassic Jiulongshan Formation of Daohugou in eastern Inner Mongolia, China. Based on the new materials, the name of two species in Eoptychopterina from China--Eoptychopterina elenae Ren and Krzeminski and Eoptychopterina gigantea Zhang--is sysnonymum junius.

  17. New fossil mayflies (Insecta: Ephemeroptera) from the Middle Jurassic of Daohugou, Inner Mongolia, China

    Institute of Scientific and Technical Information of China (English)

    Jian-Dong Huang; Dong Ren; Nina D. Sinitshenkova; Chung-Kun Shih

    2008-01-01

    Jurassonurus amoenus, a new genus and species of Siphlonuridae s. l. is described from the Middle Jurassic Jiulongshan Formation of the Daohugou Village, Shantou Township, Ningcheng County, Inner Mongolia, China. The new species is established by more than 20 imago and subimago specimens in relatively good condition. Detailed description and illustration of the specimens along with a review of fossil Siphlonuridae s.l. are given. Comparing with two known dominant nymph species Fuyous gregarious Zhang and Kluge, 2007 and Shantous lacustri Zhang and Kluge, 2007 from the same locality, we could not find any relationship among them. The new species is another dominant species in Daohugou beds.

  18. Middle Jurassic continental biota and paleolandscape in the Dubinino locality (Sharypovo area, Krasnoyarsk krai)

    Science.gov (United States)

    Ivantsov, S. V.; Bystritskaya, L. I.; Krasnolutskii, S. A.; Lyalyuk, K. P.; Frolov, A. O.; Alekseev, A. S.

    2016-09-01

    On the basis of the lithological-facies analysis, it was established that deposits of the Upper Itat Subformation, comprising the Dubinino locality of the Middle Jurassic flora and insects (Sharypovo district, Krasnoyarsk krai), accumulated in alluvial and lacustrine and, to a lesser extent, floodplain environments (floodplain and alluvial fan facies). The occurrence of remains of insects, macroremains of flora, spores, and pollen allowed us to make a paleoreconstruction of an area with a strongly dissected relief: continental fresh-water reservoir (lake) with varying degree of overflow, surrounded by hills covered with gymnospermous and ginkgo forests.

  19. The Jurassic of Denmark and Greenland: Early and Middle Jurassic mires of Bornholm and the Fennoscandian Border Zone: a comparison of depositional environments and vegetation

    Directory of Open Access Journals (Sweden)

    Koppelhus, Eva B.

    2003-10-01

    Full Text Available Suitable climatic conditions for peat formation existed during Early–Middle Jurassic times in the Fennoscandian Border Zone. Autochthonous peat and allochthonous organic matter were depositedfrom north Jylland, south-east through the Kattegat and Øresund area, to Skåne and Bornholm. The increase in coal seam abundance and thickness from north Jylland to Bornholm indicates that the most favourable peat-forming conditions were present towards the south-east. Peat formation and deposition of organic-rich muds in the Early Jurassic coastal mires were mainly controlled by a continuous rise of relative sea level governed by subsidence and an overall eustatic rise. Watertable rise repeatedly outpaced the rate of accumulation of organic matter and terminated peat formationby lacustrine or lagoonal flooding. Organic matter accumulated in open-water mires and in continuously waterlogged, anoxic and periodically marine-influenced mires. The latter conditionsresulted in huminite-rich coals containing framboidal pyrite. The investigated Lower Jurassic seams correspond to peat and peaty mud deposits that ranged from 0.5–5.7 m in thickness, but were generallyless than 3 m thick. It is estimated that on Bornholm, the mires existed on average for c. 1200 years in the Hettangian–Sinemurian and for c. 2300 years in the Late Pliensbachian; the Early Jurassic(Hettangian–Sinemurian mires in the Øresund area existed for c. 1850 years. Aalenian uplift of the Ringkøbing–Fyn High and major parts of the Danish Basin caused a significant change in the basinconfiguration and much reduced subsidence in the Fennoscandian Border Zone during the Middle Jurassic. This resulted in a more inland position for the Middle Jurassic mires which on occasionenabled peat accumulation to keep pace with, or temporarily outpace, watertable rise. Thus, peat formation was sometimes sustained for relatively long periods, and the mires may have existed for up to 7000 years in the

  20. Fe-Ni Micrometorites from Upper Jurassic Cañadon Asfalto Fm., Patagonia, Argentina

    Science.gov (United States)

    Matteini, M.; Hauser, N.; Cabaleri, N.; Silva Nieto, D.; Cuadros, F. A.; Reyes, S.

    2014-09-01

    Microspherules from an upper Jurassic sediments from Patagonia, show mineralogical, geochemical and textural features very similar to those reported for I-type micrometeorites whereas some spherules are interpreted as typical G-type micrometeorites.

  1. A Middle Jurassic abelisaurid from Patagonia and the early diversification of theropod dinosaurs.

    Science.gov (United States)

    Pol, Diego; Rauhut, Oliver W M

    2012-08-22

    Abelisaurids are a clade of large, bizarre predatory dinosaurs, most notable for their high, short skulls and extremely reduced forelimbs. They were common in Gondwana during the Cretaceous, but exceedingly rare in the Northern Hemisphere. The oldest definitive abelisaurids so far come from the late Early Cretaceous of South America and Africa, and the early evolutionary history of the clade is still poorly known. Here, we report a new abelisaurid from the Middle Jurassic of Patagonia, Eoabelisaurus mefi gen. et sp. nov., which predates the so far oldest known secure member of this lineage by more than 40 Myr. The almost complete skeleton reveals the earliest evolutionary stages of the distinctive features of abelisaurids, such as the modification of the forelimb, which started with a reduction of the distal elements. The find underlines the explosive radiation of theropod dinosaurs in the Middle Jurassic and indicates an unexpected diversity of ceratosaurs at that time. The apparent endemism of abelisauroids to southern Gondwana during Pangean times might be due to the presence of a large, central Gondwanan desert. This indicates that, apart from continent-scale geography, aspects such as regional geography and climate are important to reconstruct the biogeographical history of Mesozoic vertebrates.

  2. Middle Jurassic spinicaudatan Shizhuestheria from the Sichuan Basin and its ontogenetic implication

    Institute of Scientific and Technical Information of China (English)

    HIRANO; Hiromichi; KOZAI; Takeshi; SAKAI; Takashi

    2009-01-01

    The diagnosis of the Middle Jurassic spinicaudatan genus Shizhuestheria is revised following the re-examination under a scanning electron microscope of a type specimen from Yanxi of Shizhu, and the newly collected specimens from Xintiangou of Chengjiang Town, Beibei, Chongqing. Small-sized reticulations occur not only in the middle-sized reticulations on growth bands on the dorsal side of the carapace, but also on growth bands on the ventral side of the carapace, which have been overlooked in the original description. The shift from wide dorsal growth bands to narrow ventral ones might indicate an onset of sexual maturity, and the transition in biological priorities from rapid juvenile growth to reproductive activities.

  3. New theropod, thyreophoran, and small sauropod tracks from the Middle Jurassic Bagå Formation, Bornholm, Denmark

    DEFF Research Database (Denmark)

    Milàn, Jesper

    2011-01-01

    Three new dinosaur tracks are described from the Middle Jurassic Bagå Formation of Bornholm, Denmark. The tracks are all preserved as natural casts on the underside of fluvial sandstone blocks originating from the old Hasle Klinkefabrik’s clay pit, now called Pyritsøen. The new tracks are from...... a medium-sized theropod, a thyreophoran, and a small sauropod. Together with a hyreophoran track and large sauropod tracks described in 2005, the Middle Jurassic dinosaur fauna of Bornholm now comprises theropods, two sizes of sauropods and at least one type of thyreophoran dinosaur. This is important...

  4. Didactyl tracks of paravian theropods (Maniraptora from the ?Middle Jurassic of Africa.

    Directory of Open Access Journals (Sweden)

    Alexander Mudroch

    Full Text Available BACKGROUND: A new dinosaur tracksite from ?Middle Jurassic sediments of the Irhazer Group on the plains of Agadez (Rep. Niger, northwest Africa revealed extraordinarily well preserved didactyl tracks of a digitigrade bipedal trackmaker. The distinct morphology of the pes imprints indicates a theropod trackmaker from a paravian maniraptoran closely related to birds. METHODOLOGY/PRINCIPAL FINDINGS: The early age and the morphological traits of the tracks allow for description of the new ichnotaxon Paravipus didactyloides. A total of 120 tracks are assigned to 5 individual trackways. The 'medium-sized' tracks with an average footprint length of 27.5 cm and footprint width of 23.1 cm are deeply imprinted into the track bearing sandstone. CONCLUSIONS/SIGNIFICANCE: A comparison with other didactyl tracks gives new insights into the foot morphology of advanced maniraptoran theropods and contributes to knowledge of their evolutionary history. The new ichnotaxon takes an important position in the ichnological fossil record of Gondwana and the mid-Jurassic biota worldwide, because it is among the earliest known records of paravian maniraptorans and of didactyl theropod tracks from Africa.

  5. A new early brachyuran (Crustacea, Decapoda) from the Middle Jurassic of northwest France, epibionts and ecological considerations

    NARCIS (Netherlands)

    Robin, N.; Bakel, van B.W.M.; Hondt, d' J.-L.; Charbonnier, S.

    2015-01-01

    The earliest known crabs are of Early and Middle Jurassic age; in general, they are rare. Here we describe a new species of homolodromioid from the late Bathonian of Sarthe (France), based on a single dorsal carapace, Tanidromites raboeufi n. sp. This specimen has mostly well-preserved cuticle, and

  6. A New Family of Moths from the Middle Jurassic(Insecta:Lepidoptera)

    Institute of Scientific and Technical Information of China (English)

    HUANG Diying; André NEL; Jo(e)l MINET

    2010-01-01

    Three lepidopteran species,from the Middle Jurassic Daohugou beds(inner Mongolia,China),are described in a new family,Mesokristeuseniidae,and new genus,Mesokristensenia,which could represent the sister group of the Micropterigidae.Mesokristensenia differs from all extant Lepidoptera,but one genus(Agathiphaga,Agathiphagidae),in retaining four median veins in the forewing,a plesiomorphy also present in many Trichoptera.Evidence for placing Mesokristensenia in the Lepidoptera includes four traits,notably a previously unrecorded autapomorphy of this insect order:beyond stem M1+2,vein M1 is bent and connected to cross-vein r-m(in both wing pairs).Among 24 characters taken into account to assess the systematic position of Mesokristensenia,12 are considered informative for a cladistic analysis involving this fossil taxon and the four suborders recognized in present-day Lepidoptera(Zeugloptera,Aglossata,Heterobathmiina,and Glossata).

  7. New discovery of Palaeontinid fossils from the Middle Jurassic in Daohugou, Inner Mongolia (Homoptera, Palaeontinidae)

    Institute of Scientific and Technical Information of China (English)

    SHIH; ChungKun

    2007-01-01

    Three new species of fossil Palaeontinidae are described from Daohugou Village, Inner Mongolia, China: Daohugoucossus shii sp. nov., D. parallelivenius sp. nov., D. lii sp. nov. The diagnosis of Dao- hugoucossus Wang, Zhang and Fang, 2006 is revised. These materials are the first complete fossil palaeontinids in the Middle Jurassic of the world. Based on observation of these new specimens, Sc of this new genus has the following combined characters: joined with R at base, diverged near M separa- tion, coalesced with R before the nodal line, extended beyond the nodal line and fused with R1 before distal end. Due to the Sc characteristics mentioned above, the genus Liaocossus Ren, Yin and Dou, 1998 can be well distinguished from “Ilerdocossus-complex”.

  8. The vertebrate fauna from the stipite layers of the Grands Causses (Middle Jurassic, France

    Directory of Open Access Journals (Sweden)

    Fabien eKnoll

    2014-09-01

    Full Text Available The stipites are Bathonian (Middle Jurassic coals that formed in an everglades-like environment and are now exposed in the Grands Causses (southern France. The vertebrate assemblage of the stipites and of the transitional layers to the carbonates in which they are interspersed are reviewed. To date, only small-sized and isolated vertebrate bones, teeth, and scales have been recovered. These record the presence of sharks (Hybodus, Asteracanthus, bony fishes (Lepidotes, Pycnodontiformes, Caturus, Aspidorhynchus, amphibians (Anura, Albanerpetontidae, and reptiles (Crocodylomorpha, Ornithischia, Theropoda. Despite its relatively limited taxonomic diversity, the vertebrate assemblage from the stipites and from their associated layers is notable for being one of the few of this age with both terrestrial and marine influences. Compared to other approximately coeval formations in Western Europe, the stipites vertebrate assemblage is surpassed in diversity only by those from the British Isles.

  9. A new sauropod dinosaur from the Middle Jurassic of the United Kingdom.

    Science.gov (United States)

    Manning, Phillip L; Egerton, Victoria M; Romano, Mike

    2015-01-01

    A new record of a sauropodomorph dinosaur is here described from the Middle Jurassic (Aalenian) Saltwick Formation of Whitby (Yorkshire), UK. A single caudal vertebra represents an early sauropodomorph and signifies the earliest recognised eusauropod dinosaur from the United Kingdom. The absence of pleurocoels and a narrow, dorsoventrally deep, but craniocaudally short centrum, suggests a primitive sauropodomorph. Distinct spinopostzygopophyseal laminae rise from the lateral margins of the postzygapophyses and pass caudally along what remains of the neural spine, a character unique to a subgroup of sauropods that includes Barapasaurus, Omeisaurus and other neosauropods and eusauropods. The lack of phylogenetically robust characters in sauropod caudal vertebrae usually makes it difficult to establish affinities, but the absence of mild procoely excludes this specimen from both Diplodocoidea and Lithostrotia. The vertebra cannot be further distinguished from those of a wide range of basal sauropods, cetiosaurids and basal macronarians. However, this plesiomorphic vertebra still signifies the earliest stratigraphic occurrence for a British sauropod dinosaur.

  10. A new sauropod dinosaur from the Middle Jurassic of the United Kingdom.

    Directory of Open Access Journals (Sweden)

    Phillip L Manning

    Full Text Available A new record of a sauropodomorph dinosaur is here described from the Middle Jurassic (Aalenian Saltwick Formation of Whitby (Yorkshire, UK. A single caudal vertebra represents an early sauropodomorph and signifies the earliest recognised eusauropod dinosaur from the United Kingdom. The absence of pleurocoels and a narrow, dorsoventrally deep, but craniocaudally short centrum, suggests a primitive sauropodomorph. Distinct spinopostzygopophyseal laminae rise from the lateral margins of the postzygapophyses and pass caudally along what remains of the neural spine, a character unique to a subgroup of sauropods that includes Barapasaurus, Omeisaurus and other neosauropods and eusauropods. The lack of phylogenetically robust characters in sauropod caudal vertebrae usually makes it difficult to establish affinities, but the absence of mild procoely excludes this specimen from both Diplodocoidea and Lithostrotia. The vertebra cannot be further distinguished from those of a wide range of basal sauropods, cetiosaurids and basal macronarians. However, this plesiomorphic vertebra still signifies the earliest stratigraphic occurrence for a British sauropod dinosaur.

  11. A New Mamenchisaurid Dinosaur from the Middle Jurassic of Yuanmou, Yunnan Province, China

    Institute of Scientific and Technical Information of China (English)

    L(U) Junchang; LI Tianguang; ZHONG Shimin; JI Qiang; LI Shaoxue

    2008-01-01

    A new mamenchisaurid dinosaur, Eomamenchisaurus yuanmouensis gen et sp. nov. Is erected based on an incomplete skeleton from the Zhanghe Formation, the Middle Jurassic of Yuanmou, Yunnan Province. The new taxon is characterized by absence of pleurocoels in dorsal vertebrae and the dorsal verterbrae with slightly convex anterior articular surfaces, moderately concave posterior articular surfaces; the fourth trochanter is developed posteromedially on the femur; length ratio of the tibia to the femur is approximately 0.64; and the shaft of the ischium is rod-like. Two fused centra of the posterior dorsal vertebrae (the presumed 9th and the 10th dorsal vertebrae) are similar to those in other mamenchisaurid dinosaurs, including Mamenchisaurus hochuanesis, M. youngi and Chuanjiesaurus anaensis. Therefore, fusion of centra of the ninth and the tenth dorsal vertebrae can be recognized as a synapomorphic character of the Mamenchisauridae.

  12. The cranial osteology of Tyrannoneustes lythrodectikos (Crocodylomorpha: Metriorhynchidae) from the Middle Jurassic of Europe.

    Science.gov (United States)

    Foffa, Davide; Young, Mark T

    2014-01-01

    Tyrannoneustes lythrodectikos is one of numerous metriorhynchid crocodylomorph species known from the Oxford Clay Formation of England (Callovian-Oxfordian; Middle-Late Jurassic). This taxon is of evolutionary importance, as it is the oldest and most basal known macrophagous metriorhynchid. It has a mosaic of plesiomorphic and derived feeding related characteristics, including: teeth with microscopic, poorly formed and non-contiguous denticles; increased tooth apicobasal length; ventrally displaced dentary tooth row (increased gape); reduced dentary tooth count; and a proportionally long mandibular symphysis. However the type specimen, and current referred specimens, all lack a preserved cranium. As such, the craniofacial morphology of this taxon, and its potential feeding ecology, remains poorly understood. Here we describe two skulls and two lower jaws which we refer to T. lythrodectikos. Previously these specimens were referred to 'Metriorhynchus' brachyrhynchus. They share with the T. lythrodectikos holotype: the in-line reception pits on the dentary, dorsal margin of the surangular is strongly concave in lateral view, and the most of the angular ventral margin is strongly convex. Based on our description of these specimens, the skull of T. lythrodectikos has three autapomorphies: very long posterior processes of the premaxilla terminating in line with the 4th or 5th maxillary alveoli, deep lateral notches on the lateral surface of the maxillary with reception pits for dentary teeth, and the premaxilla forms the anterior margin of the first maxillary alveoli. Our description of the cranial anatomy of Tyrannoneustes lythrodectikos confirms that some macrophagous characteristics evolved during the Middle Jurassic, and were not exclusive to the clade Geosaurini. Moreover, the skulls further highlight the mosaic nature of Tyrannoneustes lythrodectikos and wide-gape macrophagous evolution in Geosaurinae.

  13. Architecture and development of the alluvial sediments of the Upper Jurassic Tordillo Formation in the Cañada Ancha Valley, northern Neuquén Basin, Argentina

    Science.gov (United States)

    López-Gómez, José; Martín-Chivelet, Javier; Palma, Ricardo M.

    2009-07-01

    The Upper Jurassic Tordillo Formation at Cañada Ancha area, northern Neuquén Basin, Argentina, comprises a multi-stage suit of predominantly alluvial sediments that is heterolithic in nature. In that suit, several lithofacies, architectural elements, and bounding surfaces of different order have been identified and their lateral and vertical distribution characterized. This analysis allowed the differentiation of 3 main units (lower, middle and upper), 20 subunits (C-1 to C-20), and the characterization of their alluvial styles. The lower unit (which comprises subunits C-1 to C-4) is mainly formed by fine- to medium-grained sandstones, which become medium- to coarse-grained towards the top. These sandstones characterize settings ranging from floodplains with isolated, unconfined flows, to more complex, vertically stacked, multi-storey sheet sandstones of braided fluvial systems. The middle unit (C-5 to C-10) is dominated by pale brown-grey fine-to coarse-grained sands and medium size subangular to angular conglomerates, which reflect amalgamated complexes of sandstone sheets and downstream accretion macroforms. Remarkably, this alluvial sedimentation was episodically punctuated by volcaniclastic flows. The upper unit (C-11 to C-20) consists of finer sediments, mainly pink to white fine-to medium grained sandstones and red to green siltstones. Towards the top, bioturbation becomes important, and also the presence of volcanosedimentary flows is noticeable. Fluvial settings include braided sheet sandstones with waning flood deposits evolving to isolated high-sinuosity fluvial systems, with flash flood deposits. At the top of this unit, facies may suggest marine influence. Vertical changes in the fluvial style result from both climatic and tectonic controls. A semiarid to arid climate and the active tectonism linked to the eastward migration of the Andean volcanic arc determined major bounding surfaces, fluvial style evolution and the presence of the volcano

  14. Middle Jurassic (Bajocian and Bathonian) dinosaur megatracksites, Bighorn Basin, Wyoming, USA

    Science.gov (United States)

    Kvale, E.P.; Johnson, G.D.; Mickelson, D.L.; Keller, K.; Furer, L.; Archer, A.

    2001-01-01

    Two previously unknown rare Middle Jurassic dinosaur megatracksites are reported from the Bighorn Basin of northern Wyoming in the Western Interior of the United States. These trace fossils occur in carbonate units once thought to be totally marine in origin, and constitute the two most extensive Middle Jurassic dinosaur tracksites currently known in North America. The youngest of these occurs primarily along a single horizon at or near the top of the "basal member" of the "lower" Sundance Formation, is mid-Bathonian in age, and dates to ??? 167 ma. This discovery necessitates a major change in the paleogeographic reconstructions for Wyoming for this period. The older tracksites occur at multiple horizons within a 1 m interval in the middle part of the Gypsum Spring Formation. This interval is uppermost Bajocian in age and dates to ??? 170 ma. Terrestrial tracks found, to date, have been all bipedal tridactyl dinosaur prints. At least some of these prints can be attributed to the theropods. Possible swim tracks of bipedal dinosaurs are also present in the Gypsum Spring Formation. Digitigrade prints dominate the Sundance trackways, with both plantigrade and digitigrade prints being preserved in the Gypsum Spring trackways. The Sundance track-bearing surface locally covers 7.5 square kilometers in the vicinity of Shell, Wyoming. Other tracks occur apparently on the same horizon approximately 25 kilometers to the west, north of the town of Greybull. The Gypsum Spring megatracksite is locally preserved across the same 25 kilometer east-west expanse, with the Gypsum Spring megatracksite more extensive in a north-south direction with tracks occurring locally across a 100 kilometer extent. Conservative estimates for the trackway density based on regional mapping in the Sundance tracksite discovery area near Shell suggests that over 150, 000 in situ tracks may be preserved per square kilometer in the Sundance Formation in this area. Comparable estimates have not been made

  15. Magnetostratigraphy of the middle-upper Jurassic sedimentary sequences at Yanshiping, Qiangtang Basin, China

    Science.gov (United States)

    Song, Chunhui; Zeng, Yongyao; Yan, Maodu; Wu, Song; Fang, Xiaomin; Bao, Jing; Zan, Jinbo; Liu, Xifang

    2016-09-01

    A series of important geological events occurred in the Tibetan Plateau area during the Jurassic, such as the collision of the Lhasa and Qiangtang Terranes, the closure of the Meso-Tethyan Ocean, the opening of the Neo-Tethyan Ocean and the cessation of the mega-monsoon. The ˜3000 m thick Jurassic sedimentary sequence in the Qiangtang Basin on the central Tibetan Plateau, which is called the Yanshiping (YSP) Group, recorded these geological events. However, the chronology of the sequence is surprisingly poorly constrained. Here, we perform a detailed palaeomagnetic analysis on the ˜1060 m thick middle and upper portions of the YSP Group (the Xiali and Suowa Formations) in the YSP section of the eastern Qiangtang Basin. Three bivalve zones at stratigraphic intervals of ˜40-140, 640-800 and 940-1040 m are identified, which yield a Bathonian-Callovian age for the Lower Xiali Fm., a Callovian-Oxfordian age for the Lower Suowa Fm. and an Oxfordian-Kimmeridgian age for the Upper Suowa Fm. A total of 544 oriented palaeomagnetic samples were collected from the section. By combining thermal and alternating field demagnetizations, clear characteristic remanent magnetization (ChRM) directions are isolated for most of the samples. The robust ChRM directions pass fold and reversals tests, which support the primary nature of the ChRMs and yield a palaeopole at 76.8°N/297.2°E (dp = 2.2°, dm = 3.7°). A total of 27 normal and 26 reversed polarity zones were successfully recorded in the section. Combined with fossil age constraints, results suggest that the section is plausibly composed of a Callovian-Early Kimmeridgian age sedimentary sequence.

  16. Radiometric Dating of Ignimbrite from Inner Mongolia Provides no Indication of a Post-Middle Jurassic Age for the Daohugou Beds

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Lacustrine deposits exposed at Daohugou, Inner Mongolia, China, have yielded superbly preserved vertebrate fossils. The fossil beds were first misinterpreted as of Early Cretaceous age, based on alleged occurrences of key fossils of the Jehol Biota. Compelling evidence revealed by more rigorous research involving regional biostratigraphy, radiometric dating, and paleontology supports the Middle Jurassic age of the fossil beds. Despite the awesome evidence for the Middle Jurassic age of the Daohugou beds, the age dispute has been resurrected recently by invoking an overturned stratigraphic sequence. A careful review of the data, however, found no evidence that this sequence has been overturned. In addition, many of the assumptions, on which the conjecture of the fossil beds being postMiddle Jurassic is imprudently based, are self-contradictory or otherwise misleading. Thus, the postMiddle Jurassic age of the Daohugou beds as an unfounded conclusion can readily be dismissed.

  17. Middle Jurassic - Early Cretaceous rifting on the Chortis Block in Honduras: Implications for proto-Caribbean opening (Invited)

    Science.gov (United States)

    Rogers, R. D.; Emmet, P. A.

    2009-12-01

    Regional mapping integrated with facies analysis, age constraints and airborne geophysical data reveal WNW and NE trends of Middle Jurassic to Early Cretaceous basins which intersect in southeast Honduras that we interpret as the result of rifting associated with the breakup of the Americas and opening of the proto-Caribbean seaway. The WNW-trending rift is 250 km long by 90 km wide and defined by a basal 200 to 800 m thick sequence of Middle to Late Jurassic fluvial channel and overbank deposits overlain by transgressive clastic shelf strata. At least three sub-basins are apparent. Flanking the WNW trending rift basins are fault bounded exposures of the pre-Jurassic continental basement of the Chortis block which is the source of the conglomeratic channel facies that delineate the axes of the rifts. Cretaceous terrigenous strata mantle the exposed basement-cored rift flanks. Lower Cretaceous clastic strata and shallow marine limestone strata are dominant along this trend indicating that post-rift related subsidence continued through the Early Cretaceous. The rifts coincide with a regional high in the total magnetic intensity data. We interpret these trends to reflect NNE-WSW extension active from the Middle Jurassic through Early Cretaceous. These rifts were inverted during Late Cretaceous shortening oriented normal to the rift axes. To the east and at a 120 degree angle to the WNW trending rift is the 300 km long NE trending Guayape fault system that forms the western shoulder of the Late Jurassic Agua Fria rift basin filled by > 2 km thickness of clastic marine shelf and slope strata. This NE trending basin coincides with the eastern extent of the surface exposure of continental basement rocks and a northeast-trending fabric of the Jurassic (?) metasedimentary basement rocks. We have previously interpreted the eastern basin to be the Jurassic rifted margin of the Chortis block with the Guayape originating as a normal fault system. These two rifts basin intersect

  18. A large and complete Jurassic geothermal field at Claudia, Deseado Massif, Santa Cruz, Argentina

    Science.gov (United States)

    Guido, Diego M.; Campbell, Kathleen A.

    2014-04-01

    Late Jurassic geothermal deposits at Claudia, Argentinean Patagonia, are among the largest (40 km2) and most varied in the Deseado Massif, a 60,000 km2 volcanic province hosting precious metals (Au, Ag) mineralization generated during diffuse back arc spreading and opening of the South Atlantic Ocean. Both siliceous sinter and travertine occur in the same stratigraphic sequence. Deposits range from those interpreted as fluvially reworked hydrothermal silica gels, to extensive apron terraces, to a clustering of high-temperature subaerial vent mounds. Paleoenvironmentally diagnostic textures of sinters include wavy laminated, bubble mat and nodular fabrics, and for travertines comprise fossil terracette rims, wavy laminated, bubble mat, spherulitic, oncoidal, and peloidal fabrics. Of special note is the presence of relatively large (to 25 cm high), inferred subaqueous "Conophyton" structures in travertines, which serve as analogs for some Precambrian stromatolites and imply the presence of relatively deep pools maintained by voluminous spring discharges. The Claudia geothermal field is geographically and geologically linked to the Cerro Vanguardia epithermal project (total resource of ~ 7.8 million ounces Au equivalent) via proximity, similar veins, and structural linkages, making it an especially large and relevant prospect for the region. The combined Claudia-Cerro Vanguardia hydrothermal system likely represents a fortuitous alignment of focused fluid flow and structure conducive to forming a giant epithermal ore deposit, with respect to size, ore concentration and potentially duration, in the Late Jurassic of Patagonia.

  19. Upper Jurassic and Lower Cretaceous of Sanjiang-Middle Amur basin: Non-marine and marine correlation

    Institute of Scientific and Technical Information of China (English)

    KIRILLOVA; Galina

    2009-01-01

    A comparative analysis of Late Jurassic-Early Cretaceous strata have been done for the Sanjiang Middle Amur basin, a coaland oil-bearing area spanning the eastern Heilongjiang of northeastern China and southeastern Far East of Russia. On the basis of various fossils occurring in the formations, particularly by means of the Tithonian-Valanginian index Buchia and the late Barremian-middle Albian indicator Aucellina assemblages, the marine and non-marine Late Jurassic-Early Cretaceous strata in the basin are correlated. The Mesozoic international chronostratigraphic chart (http://www.stratigra phy.org) is established basically based on the marine rocks. To accurately date the non-marine strata, it is necessary to correlate them with the marine deposits. This study sheds new light on the dating and correlation of non-marine Upper Mesozoic. Additionally, the results would help understand the tectonics and paleogeography and thus aid the exploration of energy resources.

  20. Mineralogical, IR-spectral and geochemical monitoring of hydrothermal alteration in a deformed and metamorphosed Jurassic VMS deposit at Arroyo Rojo, Tierra del Fuego, Argentina

    Science.gov (United States)

    Biel, C.; Subías, I.; Acevedo, R. D.; Yusta, I.; Velasco, F.

    2012-04-01

    The Arroyo Rojo Zn-Pb-Cu volcanogenic massive sulfide deposit is the main deposit of the Fin del Mundo District in the Fuegian Andes, Argentina. This deposit is hosted by a Middle Jurassic volcanic and volcanoclastic sequence forming the Lemaire Formation. The latter consists, from the base up, of the following: rhyolitic and dacitic porphyritic rocks, ignimbrite, tuff, and flow. It is underlain by a pre-Jurassic basement and overlain by the hyaloclastic andesites of the Yahgán Formation. The Arroyo Rojo consists of stacked lenticular lenses that are associated with disseminated mineralization in both the footwall and the hanging wall. The internal structure of the ore lenses is marked by the occurrence of massive, semi-massive and banded facies, along with stringer and brecciated zones and minor ore disseminations. The mineral assemblage comprises mainly pyrite and sphalerite, with minor amounts of galena and chalcopyrite and rare pyrrhotite, arsenopyrite, tetrahedrite and bournonite. The ores and the volcanic host rocks have metamorphosed to greenschist facies and were overprinted by a penetrative tectonic foliation, which led to the development of mylonitic, and cataclastic textures, recrystallization and remobilization. Primary depositional characteristics and regional and hydrothermal alteration patterns were preserved despite deformation and metamorphism. Therefore, primary banding was preserved between facies boundaries. In addition, some remnants of magmatic origin are recognizable in preserved phenocrysts and volcaniclastic phenoclasts. Most of the volcanic and volcaniclastic rocks of the host sequence show a rhyolitic to rhyo-dacitic composition. Regional seafloor alteration, characterized by the presence of clinozoisite, Fe-chlorite and titanite, along with quartz and albite, is partially obliterated by hydrothermal alteration. The hydrothermal alteration is stratabound with the following assemblages, which developed from the base to top: (1) Quartz

  1. Fossils from the Middle Jurassic of China shed light on morphology of Choristopsychidae (Insecta, Mecoptera)

    Science.gov (United States)

    Qiao, Xiao; Shih, Chung Kun; Petrulevičius, Julian F.; Dong, Ren

    2013-01-01

    Abstract Choristopsychidae, established by Martynov in 1937 with a single isolated forewing, is a little known extinct family in Mecoptera. Since then, no new members of this enigmatic family have been described. Based on 23 well-preserved specimens with complete body and wings from the Middle Jurassic of northeastern China, we report one new genus and three new species of Choristopsychidae, two new species of the genus Choristopsyche Martynov, 1937: Choristopsyche perfecta sp. n. and Choristopsyche asticta sp. n.; one new species of Paristopsyche gen. n.: Paristopsyche angelineae sp. n.; and re-describe Choristopsyche tenuinervis Martynov, 1937. In addition, we emend the diagnoses of Choristopsychidae and Choristopsyche. Analyzing the forewing length/width ratios of representative species in Mecoptera, we confirm that choristopsychids have the lowest ratio of forewing length/width, meaning broadest forewings. These findings, the first fossil choristopsychids with well-preserved body structure and the first record of Choristopsychidae in China, shed light on the morphology of these taxa and broaden their distribution from Tajikistan to China, while increasing the diversity of Mesozoic Mecoptera in China. PMID:23950679

  2. A golden orb-weaver spider (Araneae: Nephilidae: Nephila) from the Middle Jurassic of China.

    Science.gov (United States)

    Selden, Paul A; Shih, ChungKun; Ren, Dong

    2011-10-23

    Nephila are large, conspicuous weavers of orb webs composed of golden silk, in tropical and subtropical regions. Nephilids have a sparse fossil record, the oldest described hitherto being Cretaraneus vilaltae from the Cretaceous of Spain. Five species from Neogene Dominican amber and one from the Eocene of Florissant, CO, USA, have been referred to the extant genus Nephila. Here, we report the largest known fossil spider, Nephila jurassica sp. nov., from Middle Jurassic (approx. 165 Ma) strata of Daohugou, Inner Mongolia, China. The new species extends the fossil record of the family by approximately 35 Ma and of the genus Nephila by approximately 130 Ma, making it the longest ranging spider genus known. Nephilidae originated somewhere on Pangaea, possibly the North China block, followed by dispersal almost worldwide before the break-up of the supercontinent later in the Mesozoic. The find suggests that the palaeoclimate was warm and humid at this time. This giant fossil orb-weaver provides evidence of predation on medium to large insects, well known from the Daohugou beds, and would have played an important role in the evolution of these insects.

  3. Fossils from the Middle Jurassic of China shed light on morphology of Choristopsychidae (Insecta, Mecoptera

    Directory of Open Access Journals (Sweden)

    Xiao Qiao

    2013-07-01

    Full Text Available Choristopsychidae, established by Martynov in 1937 with a single isolated forewing, is a little known extinct family in Mecoptera. Since then, no new members of this enigmatic family have been described. Based on 23 well-preserved specimens with complete body and wings from the Middle Jurassic of northeastern China, we report one new genus and three new species of Choristopsychidae, two new species of the genus Choristopsyche Martynov, 1937: C. perfecta sp. n. and C. asticta sp. n.; one new species of Paristopsyche gen. n.: P. angelineae sp. n.; and re-describe C. tenuinervis Martynov, 1937. In addition, we emend the diagnoses of Choristopsychidae and Choristopsyche. Analyzing the forewing length/width ratios of representative species in Mecoptera, we confirm that choristopsychids have the lowest ratio of forewing length/width, meaning broadest forewings. These findings, the first fossil choristopsychids with well-preserved body structure and the first record of Choristopsychidae in China, shed light on the morphology of these taxa and broaden their distribution from Tajikistan to China, while increasing the diversity of Mesozoic Mecoptera in China.

  4. The earliest fossil record of Panorpidae (Mecoptera from the Middle Jurassic of China

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    He Ding

    2014-08-01

    Full Text Available The early history of Panorpidae (Mecoptera is poorly known due to sparse fossil records. Up to date, only nine fossil species have been described, all from the Paleogene, except the Early Cretaceous Solusipanorpa gibbidorsa Lin, 1980. However, we suggest S. gibbidorsa is too incompletely preserved to permit even family classification. A new genus with two new species, Jurassipanorpa impunctata gen. et sp. n. and Jurassipanorpa sticta sp. n., are described based on four well-preserved specimens from the late Middle Jurassic Jiulongshan Formation of Daohugou, Inner Mongolia, China. These two new species are the earliest fossil records of Panorpidae. The new genus is erected based on a combination of forewing characters: both R1 and Rs1 with two branches, 1A reaching posterior margin of wing distad of the forking of Rs from R1, and no crossveins or only one crossvein between veins of 1A and 2A. In all four specimens, long and robust setae ranging from 0.09 to 0.38 mm in length and pointing anteriorly, are present on anal veins of forewings. The function of these setae is enigmatic.

  5. Potential ZnS fossilization of gastropods (Middle Jurassic claystones from Central Poland).

    Science.gov (United States)

    Szczepanik, Patrycja; Sawlowicz, Zbigniew

    2008-09-01

    The rich fossil fauna in the Middle Jurassic claystones that crop out in the Krakow-Czestochowa Upland is extensively replaced by sulfide minerals, mainly pyrite. Sphalerite (ZnS) is rare and restricted to the internal casts of gastropods, often together with framboidal and euhedral pyrite and calcite. Scanning electron microscopy-energy dispersive spectrometer study was undertaken to explain this curious association. The results show that although direct infilling of the carbonate shell, similar to processes occurring during pyritization, is probable, it does not explain all textures observed. We propose that the carbonate shells were initially infilled by calcite and iron sulfides and sphalerite subsequently replaced the calcite casts. Preferential occurrence of ZnS in gastropods could result from accumulation of higher concentration of zinc during the organisms' life. After death, this Zn was introduced into the carbonate making gastropods more prone to ZnS replacement. Formation of ZnS casts was probably a late diagenetic event as zinc content of the surrounding sediment does not appear to influence sphalerite formation.

  6. Tectónica jurásica en Argentina y Chile: extensión, subducción oblicua, rifting, deriva y colisiones? Jurassic tectonics in Argentina and Chile: Extension, oblique subduction, rifting, drift and collisions?

    Directory of Open Access Journals (Sweden)

    Constantino Mpodozis

    2008-12-01

    Cordillera Andina a lo largo del Batolito Subcordillerano de corta vida (190-170 Ma y en la cuenca de intra-arco liásica asociada. El magmatismo de arco cesó en el norte de la Patagonia cerca de los 170 Ma y fue reemplazado por enormes volúmenes de riolitas y dacitas jurásicas inferiores a medias de la gran provincia ígnea de Chon Aike, producida como resultado de fusión cortical de una corteza sobrecalentada durante los estadios iniciales de la ruptura del Gondwana. El rifting inicial durante el Jurásico medio a tardío tuvo lugar en la cuenca de Cañadón Asfalto y en las cuencas de Río Genguel, Río Mayo y Río Senguerr durante el Jurásico tardío, en forma ortogonal al margen continental como consecuencia de la apertura del Mar de Weddell. El magmatismo ácido estuvo asociado con extensión generalizada y culminó con la apertura oceánica de la cuenca de Rocas Verdes. Las causas del cese del magmatismo en el Batolito Subcordillerano, el origen de la provincia ácida de Chon Aike y la rotación del frente magmático hacia el Batolito Patagónico alrededor de los 150 Ma no son todavía bien entendidas. Hipótesis que vinculan este escenario tectónico mutante a la colisión de terrenos alóctonos contra el margen pacífico de Patagonia durante el Jurásico temprano a medio deberían ser tenidas en consideración.The Jurassic history of southern South America shows a complex geologic evolution which is the result of different processes that began along the western Gondwana margin during the initial stages of Pangea breakup. Andean subduction along the Pacific continental margin began in the Early Jurassic, after a period of continental-scale extension and rifting, which peaked by the end of the Triassic in central and northern Argentina and Chile. Renewal of subduction was the result of an episode of ocean growth along a series of spreading centers between North and South America when the separation of these continents began as a consequence of the activity of the

  7. Tectonic forcing of early to middle jurassic seawater Sr/Ca

    DEFF Research Database (Denmark)

    Ullmann, Clemens Vinzenz; Hesselbo, Stephen P.; Korte, Christoph

    2013-01-01

    The Jurassic Period (ca. 201–145 Ma) is marked by fundamental reorganizations of paleogeography, paleoceanography, ecosystems, and the progressive shift from aragonite to calcite as the favored marine biogenic carbonate polymorph. Sr/Ca ratios of well-preserved Jurassic oysters and belemnites from...

  8. The first metriorhynchid crocodylomorph from the Middle Jurassic of Spain, with implications for evolution of the subclade Rhacheosaurini.

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    Jara Parrilla-Bel

    Full Text Available BACKGROUND: Marine deposits from the Callovian of Europe have yielded numerous species of metriorhynchid crocodylomorphs. While common in English and French Formations, metriorhynchids are poorly known from the Iberian Peninsula. Twenty years ago an incomplete, but beautifully preserved, skull was discovered from the Middle Callovian of Spain. It is currently the oldest and best preserved metriorhynchid specimen from the Iberian Peninsula. Until now it has never been properly described and its taxonomic affinities remained obscure. METHODOLOGY/PRINCIPAL FINDINGS: Here we present a comprehensive description for this specimen and in doing so we refer it to a new genus and species: Maledictosuchus riclaensis. This species is diagnosed by numerous autapomorphies, including: heterodont dentition; tightly interlocking occlusion; lachrymal anterior process excludes the jugal from the preorbital fenestra; orbits longer than supratemporal fenestrae; palatine has two non-midline and one midline anterior processes. Our phylogenetic analysis finds Maledictosuchus riclaensis to be the basal-most known member of Rhacheosaurini (the subclade of increasingly mesopelagic piscivores that includes Cricosaurus and Rhacheosaurus. CONCLUSIONS/SIGNIFICANCE: Our description of Maledictosuchus riclaensis shows that the craniodental morphologies that underpinned the success of Rhacheosaurini in the Late Jurassic and Early Cretaceous, as a result of increasing marine specialization to adaptations for feeding on fast small-bodied prey (i.e. divided and retracted external nares; reorientation of the lateral processes of the frontal; elongate, tubular rostrum; procumbent and non-carinated dentition; high overall tooth count; and dorsolaterally inclined paroccipital processes, first appeared during the Middle Jurassic. Rhacheosaurins were curiously rare in the Middle Jurassic, as only one specimen of Maledictosuchus riclaensis is known (with no representatives discovered from

  9. Identification of Calderas Associated With The Acidic Jurassic Volcanism of Southern Patagonia, Argentina

    Science.gov (United States)

    Chernicoff, C. J.; Salani, F. M.

    During the Jurassic, the Patagonian region was subject to a predominantly acidic volcanism locally known as the Chon Aike Volcanic Province, related to the breakup of Gondwana. It comprises ignimbrites, breccias and agglomerates, and a minor component of rhyolitic and dacitic lava domes. In the study area (Río Seco region, Santa Cruz Province), the Jurassic volcanics are largely overlain by Neogene and Quaternary sediments. However, the aeromagnetic survey of this region has unravelled the magnetic pattern of the volcanics, notably two conspicuous calderas, since the young cover sediments are non-magnetic. The magnetic susceptibility of the volcanic rocks ranges 50 to 80 x 10-5 S.I., as oppossed to the nearly null values of the overlying sediments. The geological interpretation of the aeromagnetic survey is mostly based on the analytic signal of the total magnetic intensity, where two distinct sub-circular magnetic lineaments have been recognized and regarded as calderic structures. The eastern caldera, 30 km wide, is centered at 48º 52' S.L./ 68º 02' W.L., and the western caldera, 23 km wide, is centered at 48º 53' S.L. / 68º 29' W.L.. In addition, a number of smaller, high gradient magnetic anomalies have been identified and interpreted as intra- and extracaldera domes. In the eastern caldera, a number of domes follow an anular pattern of fractures regarded as the boundary of an older, outer caldera. A magnetic circular lineament located within the latter structure has been interpreted as a younger, inner caldera which presents a number of small domes in its central depression; additional domes are also located in between the two calderic structures. The western caldera is less complex since it comprises a single structure with intra-caldera domes. The total magnetic gradient (analytic signal) associated with the domes is one order of magnitude higher (0.1 to 0.2) than the mean value of the region (0.03). In addition to the anular fractures and domes, a

  10. MIDDLE JURASSIC-LOWER CRETACEOUS BIOSTRATIGRAPHY IN THE CENTRAL PONTIDES (TURKEY: REMARKS ON PALEOGEOGRAPHY AND TECTONIC EVOLUTION

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    BORA ROJAY

    1998-07-01

    Full Text Available The deposition of Jurassic-Lower Cretaceous carbonates in the Pontides was controlled mainly by the evolution of an Atlantic-type continental margin in the Tethys. The study of several stratigraphic sections from allochthonous slices and blocks of the North Anatolian Ophiolitic Melange provided insight into the Middle Jurassic-Early Cretaceous paleogeographic evolution of the Central Pontide Belt. The Callovian-Aptian successions span the Globuligerina gr. oxfordiana, Clypeina jurassica (equivalent of the Tubiphytes morronensis zone, Protopeneroplis ultragranulata (with the Haplophragmoides joukowskyi subzone, Montsalevia salevensis, Hedbergella delrioensis - Hedbergella planispira - Leupoldina - Globigerinelloides and Globigerinelloides algerianus biozones. Two major stratigraphic gaps corresponding to the pre-Callovian and Hauterivian-Early Aptian ages are recognised within the successions. Lithostratigraphic and biostratigraphic studies indicate strong similarities in the evolution of the successions in the Amasya region (Central Pontides and Biga-Bursa-Bilecik (BBB Platform (North-western Anatolia. 

  11. Study on lithogeochemistry of Middle Jurassic basalts from southern China represented by the Fankeng basalts from Yongding of Fujian Province

    Institute of Scientific and Technical Information of China (English)

    ZHOU; Jincheng; JIANG; Shaoyong; WANG; Xiaolei; YANG; Jinghong; ZHANG; Mengqun

    2006-01-01

    There exists an E-W trending Middle Jurassic volcanic zone in southern China. The Fankeng basalts in the Yongding basin of Fujian Province are considered to be a typical example. The Fankeng basalts have TiO2 contents in the range of 1.92%-3.21%. They are classified as high-Ti basalts. They also have higher total Fe (averaging FeO*= 11.09%). The Middle Jurassic Fankeng basalts from southwestern Fujian have obvious distinctive lithogeochemical features from early Cretaceous basalts from southeastern coast of China. They have higher HFSE, such as Th, Nb, Ta, Zr and Ti. Their element ratios related with HFSE, such as Zr/Ba, La/Nb, La/Ta ,Zr/Y, Ti/Y, Ba/Nb, K/Ti and Rb/Zr are similar to those of OIB. The most samples have εNd(T) of -0.70-0.24, which are near chondrite. Some samples have higher εNd(T) of 1.87-3.55.Therefore, these basaltic magmas might be derived from depleted asthenospheric mantle. The lithogeochemical characteristics of the Fankeng basalts may be caused by interaction between asthenosphere and lithosphere at the time. The (Early-)Middle Jurassic basalts and gabbros from southeastern Hunan, southern Jiangxi and northern Guangdong provinces show similar geochemical features to those of the Fankeng basalts from the Yongding of Fujian. Occurrence of these OIB-type basalts in the area may be regarded as the petrological mark of upwelling of asthenosphere at the time. Upwelling of asthenosphere has led to tectonic extension and the formation of rifted basin in the area.

  12. The Jurassic of Denmark and Greenland: Sedimentology and sequence stratigraphy of the Bryne and Lulu Formations, Middle Jurassic, northern Danish Central Graben

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    Andsbjerg, Jan

    2003-10-01

    Full Text Available The Middle Jurassic Bryne and Lulu Formations of the Søgne Basin (northern part of the Danish Central Graben consist of fluvially-dominated coastal plain deposits, overlain by interfingering shoreface and back-barrier deposits. Laterally continuous, mainly fining-upwards fluvial channel sandstones that locally show evidence for tidal influence dominate the alluvial/coastal plain deposits of the lower Bryne Formation. The sandstones are separated by units of fine-grained floodplain sediments that show a fining-upwards - coarsening-upwards pattern and locally grade into lacustrine mudstones. A regional unconformity that separates the lower Bryne Formation from the mainly estuarine upper Bryne Formation is defined by the strongly erosional base of a succession of stacked channel sandstones, interpreted as the fill of a system of incised valleys. Most of the stacked channel sandstones show abundant mud laminae and flasers, and rare herringbone structures, suggesting that they were deposited in a tidal environment, probably an estuary. Several tens of metres of the lower Bryne Formation may have been removed by erosion at this unconformity. The estuarine channel sandstone succession is capped by coal beds that attain a thickness of several metres in the western part of the Søgne Basin, but are thin and poorly developed in the central part of the basin. Above the coal beds, the Lulu Formation is dominated by various types of tidally influenced paralic deposits in the western part of the basin and by coarsening-upwards shoreface and beach deposits in central parts. Westwards-thickening wedges of paralic deposits interfinger with eastwards-thickening wedges of shallow marine deposits. The Middle Jurassic succession is subdivided into nine sequences. In the lower Bryne Formation, sequence boundaries are situated at the base of laterally continuous fluvial channel sandstones whereas maximum flooding surfaces are placed in laterally extensive floodplain

  13. Unravelling the collapse mechanisms at a Jurassic caldera of the Chon Aike silicic LIP in Southern Patagonia (47° 15 'S, 71° 40'W), Argentina

    Science.gov (United States)

    Sruoga, P.; Japas, S.; Salani, F.; Kleiman, L.; Graffigna, M.

    2008-10-01

    La Peligrosa Caldera is located at Sierra Colorada (47° 15'S, 71° 40' W) in the Chon-Aike silicic LIP. It represents an unique window to understand the eruptive mechanisms that prevailed throughout the ignimbritic flare-up in Southern Patagonia during middle to late Jurassic times. Key pieces of lithologic and structural evidences are taken into account to reconstruct the volcanic structure.

  14. Sedimentology and paleoenvironments of the Las Chacritas carbonate paleolake, Cañadón Asfalto Formation (Jurassic), Patagonia, Argentina

    Science.gov (United States)

    Cabaleri, Nora G.; Benavente, Cecilia A.

    2013-02-01

    The Las Chacritas Member is the lower part of the Cañadón Asfalto Formation (Jurassic). The unit is a completely continental limestone succession with volcanic contributions that were deposited during the development of the Cañadón Asfalto Rift Basin (Chubut province, Patagonia, Argentina). A detailed sedimentological analysis was performed in the Fossati depocenter to determine the paleoenvironments that developed in the context of this rift. The Las Chacritas Member represents a carbonate paleolake system with ramp-shaped margins associated with wetlands that were eventually affected by subaerial exposure and pedogenesis. This process is represented by three main subenvironments: a) a lacustrine setting sensu stricto (lacustrine limestone facies association), represented by Mudstones/Wackestones containing porifera spicules (F1), Intraclastic packstones (F6) and Tabular stromatolites (F10) in which deposition and diagenesis were entirely subaqueous; b) a palustrine setting (palustrine limestone facies association) containing Microbial Mudstones (F2), Intraclastic sandy packstone with ostracode remains (F3), Oncolitic packstone (F5), Brecciated limestone (F7) and Nodular-Mottled limestone (F8) representing shallow marginal areas affected by groundwater fluctuations and minor subaerial exposure; and c) a pedogenic paleoenvironment (pedogenic limestone facies association) including Intraclastic limestone (F4) and Packstones containing Microcodium (F9) facies displaying the major features of subaerial exposure, pedogenic diagenesis and the development of paleosols. The fluvial-palustrine-lacustrine succession shows a general shallow upward trend in which contraction-expansion cycles are represented (delimited by exposure and surface erosion). The variations in the successive formations reflect the responses to fluctuations in a combination of two major controls, the tectonic and local climatic variables. The predominance of the palustrine facies associations was

  15. A new long-proboscid genus of Pseudopolycentropodidae (Mecoptera from the Middle Jurassic of China and its plant-host specializations

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    ChungKun Shih

    2011-09-01

    Full Text Available We describe a new genus and species of Mecoptera with siphonate mouthparts, Sinopolycentropus rasnitsyni gen. et sp. n., assigned to the family Pseudopolycentropodidae Handlirsch, 1925. The specimen was collected from late middle Jurassic nonmarine strata of the Jiulongshan Formation in Inner Mongolia, northeastern China. The new material provides additional evidence for an early diversification of pseudopolycentropodids that was ongoing during the middle Jurassic. This diversity also adds to the variety of known pseudopolycentropodids with tubular proboscides that apparently fed on ovulate fluids produced by Mesozoic gymnosperms.

  16. Long bone histology of the stem salamander Kokartus honorarius (Amphibia: Caudata) from the Middle Jurassic of Kyrgyzstan.

    Science.gov (United States)

    Skutschas, Pavel; Stein, Koen

    2015-04-01

    Kokartus honorarius from the Middle Jurassic (Bathonian) of Kyrgyzstan is one of the oldest salamanders in the fossil record, characterized by a mixture of plesiomorphic morphological features and characters shared with crown-group salamanders. Here we present a detailed histological analysis of its long bones. The analysis of a growth series demonstrates a significant histological maturation during ontogeny, expressed by the progressive appearance of longitudinally oriented primary vascular canals, primary osteons, growth marks, remodelling features in primary bone tissues, as well as progressive resorption of the calcified cartilage, formation of endochondral bone and development of cartilaginous to bony trabeculae in the epiphyses. Apart from the presence of secondary osteons, the long bone histology of Kokartus is very similar to that of miniaturized temnospondyls, other Jurassic stem salamanders, miniaturized seymouriamorphs and modern crown-group salamanders. We propose that the presence of secondary osteons in Kokartus honorarius is a plesiomorphic feature, and the loss of secondary osteons in the long bones of crown-group salamanders as well as in those of miniaturized temnospondyls is the result of miniaturization processes. Hitherto, all stem salamander long bong histology (Kokartus, Marmorerpeton and 'salamander A') has been generally described as having paedomorphic features (i.e. the presence of Katschenko's Line and a layer of calcified cartilage), these taxa were thus most likely neotenic forms. The absence of clear lines of arrested growth and annuli in long bones of Kokartus honorarius suggests that the animals lived in an environment with stable local conditions.

  17. A detrital record of continent-continent collision in the Early-Middle Jurassic foreland sequence in the northern Yangtze foreland basin, South China

    Science.gov (United States)

    Qian, Tao; Liu, Shaofeng; Wang, Zongxiu; Li, Wangpeng; Chen, Xinlu

    2016-12-01

    The Mesozoic northern Yangtze foreland basin system was formed by continental collision between the North China and South China plates along the Mianlue suture. Synorogenic stratigraphic sequences of Late Triassic to Early-Middle Jurassic age were developed in the northern Yangtze foreland basin. The upper Middle Jurassic Shaximiao Formation consists mainly of thick-bedded terrestrial successions that serve as the main body of the basin-filling sequences, suggesting intense tectonism in the peripheral orogeny of the foreland basin. Laser-ICP-MS U-Pb analysis of 254 detrital zircon grains from sandstone samples and several published Lower-Middle Jurassic samples, detrital compositions, petrofacies, and paleocurrent reconstructions in the northern Yangtze foreland basin indicate that discrete source areas included the Qinling-Dabieshan ranges and the Mianlue suture zone to the north, and the South China plate to the south. The stratigraphic succession and sediment provenance of the foreland basin imply that the early Mianlue oceanic basin, magmatic arc, and nonmarine molasse foreland basin during the period of deposition were modified or buried by the subsequent continent-continent collision between the North China-Qinling-Dabieshan plate and the Yangtze plate during the Jurassic, which followed the oblique amalgamation between these plates during the Middle-Late Triassic.

  18. New discovery of Palaeontinid fossils from the Middle Jurassic in Daohugou,Inner Mongolia (Homoptera,Palaeontinidae)

    Institute of Scientific and Technical Information of China (English)

    WANG Ying; REN Dong; SHIH ChungKun

    2007-01-01

    Three new species of fossil Palaeontinidae are described from Daohugou Village, Inner Mongolia, China:Daohugoucossus shii sp. Nov., D. Parallelivenius sp. Nov., D. Lii sp. Nov. The diagnosis of Daohugoucossus Wang, Zhang and Fang,2006 is revised. These materials are the first complete fossil palaeontinids in the Middle Jurassic of the world. Based on observation of these new specimens, Sc of this new genus has the following combined characters:joined with R at base, diverged near M separation, coalesced with R before the nodal line, extended beyond the nodal line and fused with R1 before distal end. Due to the Sc characteristics mentioned above, the genus Liaocossus Ren, Yin and Dou, 1998 can be well distinguished from"llerdocossus-complex".

  19. The first dinosaur tracksite from Xinjiang, NW China (Middle Jurassic Sanjianfang Formation, Turpan Basin)——a preliminary report

    Institute of Scientific and Technical Information of China (English)

    Oliver WINGS; Rico SCHELLHORN; Heinrich MALLISON; Ben THUY; Wenhao WU; Ge SUN

    2007-01-01

    A new dinosaur tracksite was discovered in a steeply inclined sandstone layer of the Middle Jurassic Sanjianfang Formation in the Shanshan area of the Turpan Basin. The site is the first record of dinosaur footprints from Xinjiang Province in northwestern China. More than 150 tridactyl theropod dinosaur footprints are preserved as positive hyporeliefs on the lower bedding plane of a fine-grained sandstone body. Most of the footprints are isolated and appear to be randomly distributed. Some show well defined phalangeal pads, heels and rarely indistinct impressions of the distal part of the metatarsus. Two distinct morphotypes are present: a larger type with relatively broad pads shows similarities to Changpeipus and Megalosauripus, and a slightly smaller, slender and gracile type which is similar to Grallator, Eubrontes and Anchisauripus. In both morphotypes, digit III is the longest with a length between 11.4 and 33.6 cm. A single imprint shows prominent scratches, probably formed during slipping of the track maker.

  20. Diagenesis in porosity evolution of opening-mode fractures, Middle Triassic to Lower Jurassic La Boca Formation, NE Mexico

    Science.gov (United States)

    Laubach, Stephen E.; Ward, Meghan E.

    2006-06-01

    Opening-mode fractures (joints) in Middle Triassic to Lower Jurassic La Boca Formation sandstones, northeastern Mexico, have patterns of fracture porosity, mineral-fill structures, and size distributions not previously described from outcrop. Patterns match those found in cores from many basins. We used aperture measurements along lines of observation (scanlines), fracture-trace maps, petrography, high-resolution scanning-electron-microscope-(SEM)-based cathodoluminescence, and fluid inclusions to characterize fracture populations. Open fractures are lined by quartz that precipitated while fractures were opening, whereas sealed fractures additionally contain calcite deposited after fractures ceased opening. Large fractures and arrays of contemporaneous microfractures have consistent power-law aperture-size scaling over approximately three orders of magnitude. Our results imply that open fractures and fracture sizes depend on diagenetic state. The interplay of fracture mechanics and diagenetic history is a determinant on effective porosity within fractures and, thus, open fracture persistence, connectivity, and fluid flow.

  1. Preliminary elemental analysis of fossil insects from the Middle Jurassic of Daohugou, Inner Mongolia and its taphonomic implications

    Institute of Scientific and Technical Information of China (English)

    WANG Bo; LI JianFeng; FANG Yan; ZHANG HaiChun

    2009-01-01

    Fossil insects from the Middle Jurassic of Daohugou, Inner Mongolia were investigated using Scanning Electron Microscope (SEM) for the first time, and portions and distribution of some elements in com-pression and pyrited fossils were also revealed by X-ray Energy Dispersive Spectroscopy (EDS) at-tached to SEM. Most of compression fossil insects from the Daohugou Biota are preserved in organic remains (diagenetic products of the original organic components). A small part of compression fossils retain a comparatively high Fe concentration which probably resulted from the absorption of Fe by biopolymers during the decaying period. Pyritized insect fossils suggest that the "fossil envelop" model found in the Early Cretaceous Jehol Biota probably also occurs in the Daohugou Biota. Different preservation modes show various mechanisms of fossilization, and also suggest that several different microenvironments are present in Daohugou palaeolakes.

  2. Climatic and tectonic controls on Late Triassic to Middle Jurassic sedimentation in northeastern Guangdong Province, South China

    Science.gov (United States)

    Pang, Chong-Jin; Li, Zheng-Xiang; Xu, Yi-Gang; Wen, Shu-Nv; Krapež, Bryan

    2016-05-01

    Stratigraphic analyses document climatic and tectonic controls on the filling of a Late Triassic to early Middle Jurassic (T3-J2) basin that developed on top of a young orogenic belt in southeastern South China. About 2700 m of Carnian to Bajocian sedimentary rocks is documented in the Meizhou region, Guangdong Province. The Carnian to Rhaetian sequence is characterized by deltaic facies that are succeeded by Hettangian fluvial, shallow marine and volcaniclastic facies, and by Sinemurian to early Toarcian interdistributary bay and floodplain facies. The late Toarcian to Bajocian sequence comprises proximal alluvial to lacustrine facies that changed upwards to fluvial facies. Fossil assemblages indicate that climatic conditions changed from tropical/subtropical warm humid, to temperate humid, and then to hot arid through the Late Triassic to the Middle Jurassic. Climatically induced changes (e.g., in precipitation, vegetation and erosion) exerted a strong influence on sediment supply, whereas tectonics played a dominant role in stratigraphic evolution, accommodation generation, sedimentation pattern and volcanism. Tectonostratigraphic analysis shows that the T3-J2 basin was initiated on an orogenic belt during late-stage orogeny, and evolved into shallow-marine and volcanic environments and then back to terrestrial facies during the post-orogenic stage. This was followed by regional uplift and the development of a basin-and-range province. The order of these events is similar to that of the central Rocky Mountains, western North America during the Palaeogene. The Mesozoic basin of South China and the Eocene basins of the central Rocky Mountains highlight the importance of subduction-related subsidence above young and broad orogens.

  3. Paleontology, sedimentology and paleoenvironment of a new fossiliferous locality of the Jurassic Cañadón Asfalto Formation, Chubut Province, Argentina

    Science.gov (United States)

    Gallego, Oscar F.; Cabaleri, Nora G.; Armella, Claudia; Volkheimer, Wolfgang; Ballent, Sara C.; Martínez, Sergio; Monferran, Mateo D.; Silva Nieto, Diego G.; Páez, Manuel A.

    2011-02-01

    A new Late Jurassic assemblage of “conchostracans”, ostracods, bivalves and caddisfly cases from the locality “Estancia La Sin Rumbo”, Chubut Province (Patagonia, Argentina) is recorded. The fossils occur in the upper part of an outcropping 45 m thick volcaniclastic lacustrine sequence of yellowish tuffs and tuffites of the Puesto Almada Member, which is the upper member of the Cañadón Asfalto Formation with U/Pb age of 161 ± 3 Ma. The sequence represents one sedimentary cycle composed of a (lower) hemicycle of expansion and a (higher) hemicycle of contraction of the water body. The invertebrates lived in small freshwater bodies during the periods of expansion of the lake. The occurrence of a great number of small spinicaudatans, associated with mud-cracks, is evidence of dry climatic conditions and suggests several local mortality events. The spinicaudatan record of the fushunograptid-orthestheriid (component of the Eosestheriopsis dianzhongensis fauna) and the presence of Congestheriella rauhuti Gallego and Shen, suggest a Late Jurassic (Oxfordian to Tithonian) age. Caddisfly cases are recorded for the first time in the Cañadón Asfalto Basin.

  4. The Sahara from the Middle Jurassic to the Middle Cretaceous: Data on environments and climates based on outcrops in the Algerian Sahara

    Science.gov (United States)

    Busson, G.; Cornée, A.

    The period investigated, succeeded the Upper Triassic and Liassic-Lower Dogger arid sedimentation which was characterized by the development of large evaporitic deposits. The north-eastern part of the Algerian Sahara is specially interesting as it constitutes part of the few dated continental Jurassic outcrops in North Africa (except in the Maghreb). Continental Lower-Middle Cretaceous is also well developed in the same region. The grading of these continental series into marine series particularly in the north-eastern part of the Maghreb has been investigated from an adequate number of well spaced wells. The Middle-Upper Jurassic (Lower Taouratine) consists of an argillaceous-sandy-ferruginous series, often grey coloured and rich in filicean wood and vertebrate remains in some levels. The ferralitic alteration products denote a more humid climate than that which prevailed during the Liassic-Lower-Dogger times. These products alternate with sandy conglomeratic events confirming the influences of alternating important run-off and aeolian winnowing. The large continental Lower and Middle Cretaceous detrital nappes are discussed. They constitute the uppermost part of the series, south of the Tinrhert Hamada (Alba-Vraconian series with the more detrital lateral equivalent), west of Tademait (Gara Samani). Data on lithology and paleobiology (fishes, Dinosaurs, other vertebrates, pelecypods, gastropods, wood debris, palynoflora) permit the reconstruction of the palaeo-environment and the conditions of deposition. This is similar to the sub-desertic terrestrial sedimentation by violent and ephemeral hydrodynamism model based on the modern Darfour example. The desertic conditions which prevailed in these Saharan areas during the Cretaceous are reflected as well as their possible consequences on the sedimentation of nearby oceanic areas (Atlantic and Tethys). This detrital sedimentation is finally reviewed in the context of its tectonic origins and an attempt is made to

  5. Climate change impacts on continental weathering through the Middle Jurassic to Lower Cretaceous of Sverdrup Basin, Canadian Arctic

    Science.gov (United States)

    Galloway, Jennifer; Grasby, Stephen; Swindles, Graeme; Dewing, Keith

    2014-05-01

    Jurassic to Cretaceous strata of Sverdrup Basin, Canadian Arctic Archipelago, contain marine and non-marine successions that can be studied to reconstruct ancient paleoclimates and paleoenvironments that are poorly understood in high-latitude regions. We use element geochemistry integrated with palynology to study a continuous Aalenian to Albian-aged succession preserved in the Hoodoo Dome H-37 oil and gas well located on southern Ellef Ringnes Island near the centre of Sverdrup Basin. Cluster analysis (stratigraphically constrained incremental sum of squares; CONISS) is used to delineate four geochemical zones that are broadly coeval with major changes in palyno-assemblages interpreted to reflect changes in regional paleoclimate. Zone 1 (late Aalenian to Bathonian) is characterized by palynomorphs associated with humid and warm climate conditions. The chemical alteration index (CAI) is high in this interval, expected under this a humid and warm climate. A transition to a seasonally arid and warm climate occurred in the Bathonian and persisted until the Kimmeridgian or Valanginian (Zone 2). This interval is characterized by decreased chemical weathering, indicated by a drop in CAI. The onset of Zone 3 (Kimmeridgian or Valanginian to late Barremian or early Aptian) occurs during a transition to humid and cool climate conditions and is associated with a period of regional uplift and rifting. Zone 3 is marked by a substantial and progressive drop in CAI, indicating a transition from a weathering to transport-dominated system, possibly associated with landscape destabilization. Reduced tectonic activity in Zone 4 (early Aptian to early or mid Albian) shows a return to active chemical weathering, possibly associated with landscape stabilization, suggested by a continued increase in pollen from upland coniferous taxa. The geochemical and palynological records of Middle Jurassic to Lower Cretaceous strata of the Hoodoo Dome H-37 oil and gas well show close correlation

  6. Cyclostratigraphy of an orbitally-driven Tithonian-Valanginian carbonate ramp succession, Southern Mendoza, Argentina: Implications for the Jurassic-Cretaceous boundary in the Neuquén Basin

    Science.gov (United States)

    Kietzmann, Diego A.; Palma, Ricardo M.; Iglesia Llanos, Maria Paula

    2015-01-01

    Detailed sedimentological, sequence stratigraphical and cyclostratigraphical analyses have been made from four lower Tithonian-lower Valanginian sections of the Vaca Muerta Formation, exposed in the southern Mendoza area of the Neuquén Basin, Argentina. The Vaca Muerta Formation is characterized by decimetre-scale rhythmic alternations of marls, shales and limestones, and consists of five facies associations, which reflect different paleoenvironmental conditions: basin to restricted outer ramp, outer ramp, and middle ramp. Vertical organization within the Vaca Muerta Formation shows a well-ordered hierarchy of cycles, where elementary cycles, bundles and superbundles with frequencies within the Milankovitch band have been recognized. According to biostratigraphic data, elementary cycles have a periodicity of ~ 20 ky, which correlates with the precession cycle of Earth's axis. Spectral analysis based on series of cycle thickness allows us to identify frequencies of about 400 ky and 90-120 ky, which we interpret as the modulation of the precessional cycle by the Earth's orbital eccentricity. Cycles are probably driven by variations in carbonate exportation, as fluctuations in shallow-water carbonate production involve modifications in carbonate basinward exportation. Cyclostratigraphic data allowed us to build a floating orbital scale for the Tithonian-lower Valanginian interval in the Neuquén Basin. Correlation between studied sections allowed us to recognize a discontinuity between the Substeueroceras koeneni and Argentiniceras noduliferum ammonite zones in the Malargüe Anticline area. Orbital calibration of these sections is consistent with Riccardi's biostratigraphic scheme, wich place the Jurassic-Cretaceous boundary within the Substeueroceras koeneni ammonite Zone. On the other hand, the base of the Vaca Muerta Formation (Virgatosphinctes mendozanus ammonite Zone) would be probably placed in the base of the middle Tithonian rather than the lower Tithonian

  7. THE ROSSO AMMONITICO VERONESE (MIDDLE-UPPER JURASSIC OF THE TRENTO PLATEAU: A PROPOSALLITHOSTRATIGRAPHIC RDERING AND FORMALIZATION

    Directory of Open Access Journals (Sweden)

    LUCA MARTIRE

    2006-07-01

    Full Text Available We here propose a revision of the stratigraphic interval comprised between the top of platform carbonates, mainly of Early Jurassic age, and the base of the Maiolica, in the Trento Plateau. Most of this interval (upper Bajocian - upper Tithonian is represented by ammonite-bearing, red nodular limestones known with the historical name of Rosso Ammonitico Veronese (RAV. It has been subdivided in three units: a lower unit, calcareous and massively bedded; a middle unit, thinly bedded and cherty; and an upper unit, calcareous and nodular. In addition to these units, other sedimentary bodies are known below the base of the RAV. These are thin and discontinuous, such as the Lumachella a Posidonia alpina (LPa and the Calcari a Skirroceras (CSk, both spanning the upper Aalenian - upper Bajocian. A lithostratigraphic redefinition of the RAV is proposed by addition of two members (LPa e CSk to the three classical members. The new members are easily distinguished by their lithofacies and are always separated from the lower unit by discontinuities. Two sections located on the Altopiano di Asiago are described: Kaberlaba shows all the three members (lower, middle and upper and is proposed as the reference section for a formalization of the RAV; Rabeschini is characterized  by the absence of the middle member and may be held as a complementary section. The RAV lower boundary is everywhere very sharp and marked by a facies contrast; the upper boundary, instead, is transitional and is defined by a progressive change from red, nodular, Saccocoma packstones to white, non-nodular calpionellid wackestones. Calpionellid associations indicate that the upper boundary falls within the upper Tithonian.

  8. Response to paleoatmospheric CO2 concentration of Solenites vimineus (Phillips) Harris (Ginkgophyta) from the Middle Jurassic of the Yaojie Basin, Gansu Province, China

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Solenites vimineus (Phillips) Harris (Ginkgophyta) specimens with well-preserved cuticles were collected from five different beds in the oil shale member of the Middle Jurassic Yaojie Formation in the Yaojie Basin, Gansu Province, northwestern China. Gross morphology and fine structures of the fossil leaves were studied, and stomatal parameters were analyzed, according to which, the paleoatmospheric CO2 concentration can be deduced as 1512-1896 ppm that would have caused an increase in mean temperature of about 6.5-7.4℃. Carbon isotopes from the fossils indicate that the carbon isotopic discrimination and water use efficiency (WUE) of S. vimineus were raised nearly obtaining the ideal physiologic state in increased CO2 concentrations and temperature conditions, suggesting that S. vimineus records the paleoenvironmental information of the Middle Jurassic Yaojie Basin and can be used for environmental reconstruction.

  9. Some charophytes from the middle dinosaur member of the Tendaguru formation (Upper Jurassic of Tanzania

    Directory of Open Access Journals (Sweden)

    M. E. Schudack

    1999-01-01

    Full Text Available Biostratigraphy and paleoecology of the famous dinosaur beds of Tendaguru Formation, Tanzania, East Africa are still under discussion. Calcareous microfossils have not yet contributed to this question. Four samples from the Middle Dinosaur Member have now yielded charophyte gyrogonites of the species Aclistochara cf. bransonii, Aclistochara cf. minor, Mesochara canellata, and Mesochara harrisi. Considering ammonite datations in under- and overlying members, even their long stratigrapical ranges point to a Kimmeridgian age for the Middle Dinosaur Member of Tendaguru Formation. Salinity tolerances of the species (if autochthonous suggest a variable environment with partly brackish, partly freshwater influences. Biostratigraphie und Paläoökologie der berühmten Dinosaurier-Fundschichten am Tendaguru Hill in Tansania (Ostafrika sind bis heute umstritten. Kalkige Mikrofossilien hatten zu dieser Diskussion bisher nicht beigetragen. In vier Proben aus dem Mittleren Dinosauriermergel fanden sich nun Charophyten-Gyrogonite der Arten Aclistochara cf. bransonii, Aclistochara cf. minor, Mesochara canellata und Mesochara harrisi. Trotz generell langer stratigraphischer Reichweiten dieser Arten macht ihr Vorkommen im Zusammenhang mit Ammonitenfunden in unter- und überlagernden Schichten ein Kimmeridgium-Alter des Mittleren Dinosauriermergels wahrscheinlich, während ihre Salinitätstoleranzen (autochthones Vorkommen vorausgesetzt auf ein wechselhaftes Milieu mit teils schwach brackischen, teils Süßwassereinflüssen hindeuten. doi:10.1002/mmng.1999.4860020115

  10. Early Evolution of Apocrita(Insecta,Hymenoptera)as Indicated by New Findings in the Middle Jurassic of Daohugou,Northeast China

    Institute of Scientific and Technical Information of China (English)

    Alexandr P.PASNITSYN; ZHANG Haichun

    2010-01-01

    The classification and phylogeny of the basal Vespina(= Orussoidea+Apocrita)are reconsidered based primarily on rich and well preserved material from the Middle Jurassic of Daohugou in Inner Mongolia,China.Comparatively smooth morphological transitions are traced from a Xiphydriidae-like ancestor toward Orussoidea via the Jurassic family Karatavitidae,and through Karatavitidae and the Jurassic and Early Cretaceous family Ephialtitidae independently to Stephanidae,to Evanioidea,and,via the extinct Jurassic Kuafuidae fam.nov.to the remaining Apocrita.New hypothesis is proposed concerning development of the characteristic wasp-waist of Apocrita,which is supposed to appear independently and in different ways in Evanioidea and in the rest of Apocrita.As a result,six infraorders are proposed for the suborder Vespina with the following taxonomic structure:infraorder Orussomorpha including the only superfamily Ornssoidea(Karatavitidae+Paroryssidae+Orussidae),infraorder Stephanomorpha with the only superfamily Stephanoidea(Ephialfitidae+Stephanidae),infraorder Evaniomorpha with the only superfamily Evanioidea of traditional composition,infraorder Ceraphronomorpha with the superfamilies Ceraphronoidea s.str.and monotypical Megalyroidea and Trigonaloidea,and the infraorders Proctotrnpomorpha,lchneumonomorpha,and Vespomorpha of traditional composition.The family Kuafuidae is unplaced to infraorder because it is putatively paraphyletic with respect to Ceraphronomorpha,Proctotrupomorpha,Ichneumonomorpha and Vespomorpha.Described as new are Karatavites junfengi sp.nov.,Praeratavites wuhuaensis sp.nov.,P.perspicuus sp.nov,Postxiphydria daohugouensis gen.et sp.nov.,P.ningchengensis gen.et sp.nov.,Postxiphydroides strenuus gen.et sp.nov.,Praeratavitoides amabilis gen.et sp.nov.,Proapocritus densipediculus sp.nov.,P.sculptus sp.nov.,P.longantennatus sp.nov.,P.formosus sp.nov.,P.atropus sp.nov.,P.elegans sp.nov.,Stephanogaster pristinus sp.nov.,Asiephialtites lini sp

  11. The Middle Jurassic basinal deposits of the Surmeh Formation in the Central Zagros Mountains, southwest Iran: Facies, sequence stratigraphy, and controls

    Science.gov (United States)

    Lasemi, Y.; Jalilian, A.H.

    2010-01-01

    The lower part of the Lower to Upper Jurassic Surmeh Formation consists of a succession of shallow marine carbonates (Toarcian-Aalenian) overlain by a deep marine basinal succession (Aalenian-Bajocian) that grades upward to Middle to Upper Jurassic platform carbonates. The termination of shallow marine carbonate deposition of the lower part of the Surmeh Formation and the establishment of deep marine sedimentation indicate a change in the style of sedimentation in the Neotethys passive margin of southwest Iran during the Middle Jurassic. To evaluate the reasons for this change and to assess the basin configuration during the Middle Jurassic, this study focuses on facies analysis and sequence stratigraphy of the basinal deposits (pelagic and calciturbidite facies) of the Surmeh Formation, referred here as 'lower shaley unit' in the Central Zagros region. The upper Aalenian-Bajocian 'lower shaley unit' overlies, with an abrupt contact, the Toarcian-lower Aalenian platform carbonates. It consists of pelagic (calcareous shale and limestone) and calciturbidite facies grading to upper Bajocian-Bathonian platform carbonates. Calciturbidite deposits in the 'lower shaley unit' consist of various graded grainstone to lime mudstone facies containing mixed deep marine fauna and platform-derived material. These facies include quartz-bearing lithoclast/intraclast grainstone to lime mudstone, bioclast/ooid/peloid intraclast grainstone, ooid grainstone to packstone, and lime wackestone to mudstone. The calciturbidite layers are erosive-based and commonly exhibit graded bedding, incomplete Bouma turbidite sequence, flute casts, and load casts. They consist chiefly of platform-derived materials including ooids, intraclasts/lithoclasts, peloids, echinoderms, brachiopods, bivalves, and open-ocean biota, such as planktonic bivalves, crinoids, coccoliths, foraminifers, and sponge spicules. The 'lower shaley unit' constitutes the late transgressive and the main part of the highstand

  12. The Aguilar pluton (23°12‧ S-65°40‧ W; NW Argentina): Petrological implications on the origin of the Late Jurassic intraplate magmatism in the Central Andes

    Science.gov (United States)

    Omarini, Ricardo H.; Gioncada, Anna; Vezzoli, Luigina; Mazzuoli, Roberto; Cristiani, Chiara; Sureda, Ricardo J.

    2013-11-01

    The Late Jurassic Aguilar pluton is located in NW Argentina, about 300-400 Km east of the Tarapacá basin, representing the backarc basin linked to the Jurassic volcanic arc. This small-size and compositionally heterogeneous pluton intruded the metasedimentary rocks of the Ordovician Santa Victoria Group, along the Cobres-Salinas Grandes lineament. A revision of published geochemical data in the light of new field and petrological results, allows us to propose a model concerning the petrogenesis and emplacement mechanisms of Aguilar pluton and to discuss its geodynamic setting. The pluton is mainly composed of metaluminous and nearly peraluminous granitoids, showing the geochemical characteristics of ferroan granites. The volumetrically subordinate mafic rocks are both ne- and hy-normative, and their primary magmas were generated by partial melting of a pristine Proterozoic mantle. Aguilar rocks display a rather limited range in (87Sr/86Sr)i, compared to the entire rift-related plutonic suite, i.e., 0.703198-0.704601, and ɛNdt from -1.06 to 3.82, calculated at 149 Ma. Fractional crystallization of mantle-derived magmas and crustal contamination processes explain the evolution to produce strongly silica-oversaturated magmas, which emplaced in the continental crust. The petrological data indicate that magma emplacement and cooling occurred at rather shallow depth. Multiple injections of magma batches into the magma chamber caused mingling and mixing processes early in the crystallization history. The Aguilar pluton is one of the several igneous complexes whose formation was associated with the extensional tectonics active during Late Jurassic-Early Cretaceous in NW Argentina. Based on the geological position and the igneous rocks affinity, we exclude that the Late Jurassic magmatism was generated in an orogenic setting and envisage that it was linked to the early extensional phase that preceded the Cretaceous continental rifting, related to the break-up of the South

  13. New fossil evidence of the early diversification of scarabs:Alloioscarabaeus cheni (Coleoptera: Scarabaeoidea) from the Middle Jurassic of Inner Mongolia, China

    Institute of Scientific and Technical Information of China (English)

    Ming Bai; Dirk Ahrens; Xing-Ke Yang; Dong Ren

    2012-01-01

    Scarabaeoidea are known from the Lower Jurassic and may have originated in the Triassic based on fossil evidence and phylogenetic research.However,the early diversification of Scarabaeoidea remains unclear due to the lack of high-quality fossil evidence.Here we describe an exceptionally well-preserved new fossil of Scarabaeoidea,Alloioscarabaeus cheni gen.et sp.nov from the Middle Jurassic Jiulongshan Formation of Inner Mongolia,China.Based on a morphometric analysis using 17 landmarks of the hind wing of Alloioscarabaeus and 10 scarabaeoid families,we found that Alloioscarabaeus cheni gen.et sp.nov clearly does not belong to any of the known scarabaeoid families and,consequently,is a new family,Alloioscarabaeidae fam.nov.,was erected.The discovery of Alloioscarabaeus brought further evidence for the early diversification of major scarab lineages which could allow more detail in the palaeobiogeography of the Scarabaeoidea and Northeast of China which might be one of the originating places or an important radiation place during the evolution of Scarabaeoidea.Alloioscarabaeidae were very likely not good diggers and might have fed on decaying organic materials.Based on the evidence we have now,we tend to believe that most families and some subfamilies of Scarabaeoidea were present in the Jurassic period.

  14. A new fossil genus of Mesosciophilidae (Diptera,Nematocera) with two new species from the Middle Jurassic of Inner Mongolia,China

    Institute of Scientific and Technical Information of China (English)

    Tingting Li; Dong Ren

    2009-01-01

    A new genus within the family Mesosciophilidae,Jurasciophila gen.nov.,with two new species,J.curvula gen.et sp.nov.and J.lepida gen.et sp.nov.,are described and illustrated.They are established based on fossil specimens with bodies and complete wings.All of them were collected from the late Middle Jurassic Jiulongshan Formation of Daohugou in southeastern Inner Mongolia,China.Comparing with two known genera,Mesosciophilina (Kovalev,1985) and Mesosciophilopsis (Blagoderov,1994),the new genus has transitional characters.The distribution pattern of Mesosciophilidae is briefly discussed.

  15. Argentina

    OpenAIRE

    Nogues, Julio J.

    2005-01-01

    After decades of being a marginal player in the GATT trade negotiations, Argentina decided to participate actively in the Uruguay Round. This chapter measures the imbalance between the concessions given and received and concludes that the value of the first are far more important than the second. I discusss the economic consequence of this imbalance, and the prospects that the outcome of the Doha Round can be more balanced outcome for Argentina.

  16. Maternal immunization in Argentina: A storyline from the prospective of a middle income country.

    Science.gov (United States)

    Vizzotti, C; Neyro, S; Katz, N; Juárez, M V; Perez Carrega, M E; Aquino, A; Kaski Fullone, F

    2015-11-25

    The importance of vaccination during pregnancy lies not only in directly protecting vaccinated women, but also by indirectly protecting small infants during the first few months of life. Vaccination against the flu and whooping cough is a priority within the comprehensive care strategy for pregnant women and small infants in Argentina, in the context of transitioning from child vaccination to family vaccination. In 2011, the flu vaccine was included in the National Immunization Schedule (NIS) as mandatory and free of charge, with the aim of decreasing complications and death due to influenza in the at-risk population in Argentina. The national vaccination coverage attained in pregnant women in the past 4 years (2011-2014) has been satisfactory; 88% coverage was attained in the year this program was introduced to the schedule. In the following years, coverage was maintained at greater than 95%. In February 2012, Argentina became the first country in Latin America to have universal vaccination strategy for pregnant women against whooping cough. This recommendation was implemented throughout the country by vaccination with the diphtheria toxoid, tetanus toxoid, and acellular pertussis (Tdap) vaccine starting at 20 weeks of pregnancy, with the aim of decreasing morbimortality due to whooping cough in infants under 6 months of age. The vaccine was incorporated into the NIS in 2014. More than 1,200,000 doses were applied in this period. Both vaccines showed a suitable safety profile and no serious events were reported. Argentina is an example of a middle-income country that has been able to implement a successful strategy for primary prevention through vaccines, making it a health policy.

  17. Jurassic Park: Adventure in Learning.

    Science.gov (United States)

    Shams, Marcia; Boteler, Trina

    1993-01-01

    Describes using the movie "Jurassic Park" as a foundation for a middle school interdisciplinary unit involving science, math, language arts, history, and geography. Suggested books and activities are presented. (PR)

  18. Evaluation of the nature, origin and potentiality of the subsurface Middle Jurassic and Lower Cretaceous source rocks in Melleiha G-1x well, North Western Desert, Egypt

    Directory of Open Access Journals (Sweden)

    Mohamed M. El Nady

    2015-09-01

    Full Text Available The present work aims to evaluate the nature and origin of the source rock potentiality of subsurface Middle Jurassic and Lower Cretaceous source rocks in Melleiha G-1x well. This target was achieved throughout the evaluation of total organic carbon, rock Eval pyrolysis and vitrinite reflectance for fifteen cutting samples and three extract samples collected from Khatatba, Alam El Bueib and Kharita formations in the studied well. The result revealed that the main hydrocarbon of source rocks, for the Middle Jurassic (Khatatba Fm. is mainly mature, and has good capability of producing oil and minor gas. Lower Cretaceous source rocks (Alam El Bueib Fm. are mature, derived from mixed organic sources and have fair to good capability to generate gas and oil. Kharita Formation of immature source rocks originated from terrestrial origin and has poor to fair potential to produce gas. This indicates that Khatatba and Alam El Bueib formations take the direction of increasing maturity far away from the direction of biodegradation and can be considered as effective source potential in the Melleiha G-1x well.

  19. Petrogenesis of Early-Middle Jurassic intrusive rocks in northern Liaoning and central Jilin provinces, northeast China: Implications for the extent of spatial-temporal overprinting of the Mongol-Okhotsk and Paleo-Pacific tectonic regimes

    Science.gov (United States)

    Zhang, Hai-Hong; Wang, Feng; Xu, Wen-Liang; Cao, Hua-Hua; Pei, Fu-Ping

    2016-07-01

    The Mesozoic tectonic evolution of NE China was controlled mainly by the Mongol-Okhotsk and Paleo-Pacific tectonic regimes. However, the extent of the spatial and temporal overprinting of these two regimes is poorly understood. Here, we report new zircon LA-ICP-MS U-Pb dating and geochemical analyses of Jurassic intrusive rocks in northern Liaoning and central Jilin provinces, northeast China, to discuss their petrogenesis and outline the extent of spatial and temporal overprinting of these two tectonic regimes. Dating results indicate that Jurassic magmatism occurred in two stages during the Early (ca. 175 Ma) and Middle Jurassic (170-163 Ma). These rocks represent two-stage typical bimodal igneous rock associations composed mainly of olivine gabbro, gabbro, and gneissic granitoids. The Early and Middle Jurassic gabbros have low rare earth element (REE) abundances, positive Eu anomalies, depletion in high field strength elements (HFSEs), and positive εHf(t) values (+ 4.0 to + 10.3, except for one value of - 17.8), suggesting that the primary magma was derived from partial melting of depleted lithospheric mantle metasomatized by subducted-slab-derived fluids. The Early Jurassic monzogranite exhibit high REE abundances (195-201 ppm), weak negative Eu anomalies (δEu = 0.63-0.64), and negative εHf(t) values (- 11.9 to - 8.2), suggesting a primary magma that was derived from partial melting of lower continental crust of the NCC. The Middle Jurassic granodiorites are enriched in light REEs (LREEs) and large ion lithophile elements (LILEs), and are depleted in heavy REEs (HREEs) and HFSEs, as well as high Sr/Y (29-132) and (La/Yb)N (15-44) ratios. In addition, the Middle Jurassic granitoids near or within the NCC exhibit negative εHf(t) values (- 18.9 to + 0.2), whereas those within the Xing'an-Mongolia Orogenic Belt (XMOB) have generally positive εHf(t) values (- 0.6 to + 6.4), suggesting their origin from partial melting of thickened ancient NCC and newly accreted

  20. Diversity of cingulate xenarthrans in the middle-late Eocene of Northwestern Argentina

    Directory of Open Access Journals (Sweden)

    Martín R. Ciancio

    2016-08-01

    Full Text Available The study of Paleogene mammals of intermediate and low latitudes has increased in the last decades and has been clearly demonstrated their importance in the comprehension of the evolution and faunistic changes outside Patagonia. The study of these faunas permits establishing new comparisons among contemporaneous faunistic associations, completing the distributional patterns, and evaluating evolutionary changes in the lineages in relation to climatic conditions prevailing in each of the different regions. In this work we study the diversity of Dasypodidae recovered from the Geste Formation (Northwestern Argentina. Bearing levels of Geste Formation were referred alternatively to a Barrancan subage of Casamayoran SALMA (middle Eocene, Lutetian–Bartonian or a Mustersan SALMA (middle–late Eocene, Bartonian–Priabonian on faunistic comparations with their equivalent in Patagonia, although absolute isotopic data indicates ca. 37–35 Ma (late Eocene, Priabonian. We described the following taxa of Dasypodidae: (i Dasypodinae Astegotheriini: cf. Astegotherium sp., ?Prostegotherium sp., Parastegosimpsonia cf. P. peruana; (ii Dasypodinae indet.; (iii Euphractinae Euphractini: Parutaetus punaensis sp. nov.; (iv Dasypodidae incertae sedis: Pucatherium parvum, Punatherium catamarcensis gen. et sp. nov. In comparison with other beds bearing Eocene cingulate faunas from Northwestern Argentina, Geste Formation presents the greatest diversity of dasypodids. This association is consistent with a late Eocene age and shows a taxonomic and biogeographic relevant features given by a unique specific composition: (i it differs from that known for contemporaneous faunas from Southern latitudes and younger associations from more tropical areas; (ii it includes genera with close affinities to those distant areas; (iii it presents unique taxa typical from Eocene units exposed at Northwestern Argentina. This highlights the evolutionary and biogeographic meaning of the

  1. Argentina

    Energy Technology Data Exchange (ETDEWEB)

    1999-09-01

    This report presents a brief overview of the socio-economic, energy and environmental context in which climate change mitigation actions in Argentina shall be inserted. To that end, the dynamic of the Argentine economic development, its influence on the energy system and environmental impacts is summarised. From the environmental standpoint, emphasis shall only be made on the impact of economic development patterns and energy policies on GHG emission. (au) 73 refs.

  2. Stratigraphy and sedimentology of a basement-onlapping shallow marine sandstone succession, the Charcot Bugt Formation, Middle-Upper Jurassic, East Greenland

    Energy Technology Data Exchange (ETDEWEB)

    Larsen, M.; Piasecki, S. [Geological Survey of Denmark and Greenland, Copenhagen (Denmark)]. Geocenter; Surlyk, F. [Univ. of Copenhagen, Copenhagen (Denmark)]. Geological Inst.

    2003-07-01

    A rocky shore developed in early Middle Jurassic times by transgression of the crystalline basement in Milne'Land at the western margin of the East Greenland rift basin. The basement is onlapped by shallow marine sandstones of the Charcot Bugt Formation, locally with a thin fluvial unit at the base. The topography of the onlap surface suggests that a relative sea-level rise of at least 300 m took place in Early Bathonian - Middle Oxfordian times. The sea-level rise was punctuated by relative stillstands and falls during which progradation of the shoreline took place. Palynological data tied to the Boreal ammonite stratigraphy have greatly improved time resolution within the Charcot Bugt Formation, and the Jurassic succession in Milne Land can now be understood in terms of genetically-related depositional systems with a proximal to distal decrease in grain size. The sequence stratigraphic interpretation suggests that translation of the depositional systems governed by relative sea-level changes resulted in stacking of sandstone-dominated falling stage deposits in the Bastern, basinwards parts of Milne Land, whereas thick, remarkably coarsegrained transgressive systems tract deposits formed along the western basin margin. The bulk of the Charcot Bugt Formation consists of stacked sandstone-dominated shoreface units that prograded during highstands. The overall aggradational to backstepping stacking pattem recognised in the Charcot Bugt Formation is comparable to that in the contemporaneous Pelion Formation of the Jameson Land Basin and in correlative units of the mid-Norway shelf and the Northern North Sea. We suggest that the long-term evolution of the depositional systems may have been controlled by long-term eustatic rise acting in concert with relative sea-level changes reflecting regionally contemporaneous phases of rift initiation, dimax and gradual cessation of rifting. (au)

  3. A New Female Cone, Araucaria beipoiaoensis sp. nov. from the Middle Jurassic Tiaojishan Formation, Beipiao, Western Liaoning, China and Its Evolutionary Significance

    Institute of Scientific and Technical Information of China (English)

    ZHENG Shaolin; ZHANG Lidong; ZHANG Wu; YANG Yajun

    2008-01-01

    A new species of Araucaria, Araucaria beipiaoensis sp. nov., collected from the Middle Jurassic Tiaojishan Formation, southern hill of Shebudai village, near Beipiao city, western Liaoning is based on a permineralized female cone, which is ovate to elliptical in shape, about 11 cm×7 cm ×4.5 cm in size. The cone bears rhomboid bracts that are spirally attached, texture thicker, with wings on both sides, with a detached lamina-like apex at the tip. In inner structure the ovuliferous scales are thicker and fused with bracts at the end with a ligular sulcus. There is one wingless ovule/seed per seed-scale complex embedded in the ovuliferous scale tissue, with the micropyle directed toward the cone axis. The ovules/seeds are long ovate or elliptical in shape, I cm long and near the base about 3 mm in diameter; the ovule/seed integuments have begun differentiation into 3 layers: the sarcotesta,sclerotesta, and endotesta. The nucellus is free from the enclosing integuments except in the chalazal region where it is fused to the inner layer (endotesta) of integument. Some ovules show cellularized nucellar tissue. Mature seeds exhibit the papery-thin wavy nucellus characteristically near to the micropyle. The embryonic tissue appears to be four cotyledons. The morphology and structure of the cone shows a close relationship to the araucarian cones of fossil and living genera but differs from any known species. The new species is distributed in the Middle Jurassic of the northern hemisphere, especially Asia, and has important significance for the evolution of the Family Araucariaceae.

  4. Argentina

    Directory of Open Access Journals (Sweden)

    Karina M. Michetti

    2007-01-01

    Full Text Available Draparnaldia mutabilis posee un talo compuesto por un sistema rizoidal postrado reducido y un sistema erguido que muestra una marcada diferenciación entre filamentos axiales y laterales, estos últimos agrupados en fascículos densos, altamente ramificados. La reproducción asexual ocurre por medio de zoósporas que poseen un patrón de germinación erguido. El registro de esta especie constituye la primera cita cierta para la República Argentina. Se presenta además, una clave con las especies mejor definidas.

  5. K/Ar chronologies of tephra units from the Middle Jurassic Sundance, and Late Early Cretaceous Mowry and Shell Creek Formations, Big Horn Basin, WY

    Science.gov (United States)

    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.

  6. Reconnaissance studies of potential petroleum source rocks in the Middle Jurassic Tuxedni Group near Red Glacier, eastern slope of Iliamna Volcano

    Science.gov (United States)

    Stanley, Richard G.; Herriott, Trystan M.; LePain, David L.; Helmold, Kenneth P.; Peterson, C. Shaun

    2013-01-01

    Previous geological and organic geochemical studies have concluded that organic-rich marine shale in the Middle Jurassic Tuxedni Group is the principal source rock of oil and associated gas in Cook Inlet (Magoon and Anders, 1992; Magoon, 1994; Lillis and Stanley, 2011; LePain and others, 2012; LePain and others, submitted). During May 2009 helicopter-assisted field studies, 19 samples of dark-colored, fine-grained rocks were collected from exposures of the Red Glacier Formation of the Tuxedni Group near Red Glacier, about 70 km west of Ninilchik on the eastern flank of Iliamna Volcano (figs. 1 and 3). The rock samples were submitted to a commercial laboratory for analysis by Rock-Eval pyrolysis and to the U.S. Geological Survey organic geochemical laboratory in Denver, Colorado, for analysis of vitrinite reflectance. The results show that values of vitrinite reflectance (percent Ro) in our samples average about 2 percent, much higher than the oil window range of 0.6–1.3 percent (Johnsson and others, 1993). The high vitrinite reflectance values indicate that the rock samples experienced significant heating and furthermore suggest that these rocks may have generated oil and gas in the past but no longer have any hydrocarbon source potential. The high thermal maturity of the rock samples may have resulted from (1) the thermaleffects of igneous activity (including intrusion by igneous rocks), (2) deep burial beneath Jurassic, Cretaceous, and Tertiary strata that were subsequently removed by uplift and erosion, or (3) the combined effects of igneous activity and burial.

  7. Argentina.

    Science.gov (United States)

    1993-02-01

    Background notes on Argentina provide a profile of the geography, selected demographic features, government and economic conditions. Descriptive text includes a discussion of the people, their history and political conditions, the government and officials, the state of the economy, their defense, foreign relations, and relations with the US. The 1992 estimated population was about 33 million of whom 97% are European (mostly Spanish and Italian). Religions represented are Roman Catholic (92%), Protestant (2%), Jewish (2%), and other (4%). Adult literacy is 95%. 36% are engaged in industry and commerce, 20% in services, 19% in agriculture, 6% in transport and communications, and 19% other. Per capita gross domestic product was $4,500. There are only 50,000 native Indians remaining in peripheral provinces. The population enjoys a high standard of living and a low growth rate. The country was shaped by dominant forces: modern agricultural techniques and the integration of the country into the world economy. Foreign investment aided the economic revolution. Conservative and radical rule has swung the country back and forth politically since 1916. Colonel Juan Domingo Peron led a successful military coup in 1943 and was elected in 1946. Policies were instituted to give a greater voice to the working class, and with the influences of his wife, women's groups. In 1955, he was ousted by the military, which failed to revive the economy and quiet increasing terrorism. After a number of difficult elections, Peron was reinstated as president in 1973. Extremists on the left and right threatened public order; the military as a consequence imprisoned persons indefinitely. Peron's wife succeeded him after his death, but was removed from office in the military coup of 1976. Basic human rights were violated during this period. By 1983, a fair election was held and support increased for a democratic system. In 1989, Carlos Saul Menem, a Peronist candidate, won and established

  8. Archosaur evolution during the Jurassic: a southern perspective

    Directory of Open Access Journals (Sweden)

    Oliver W. M. Rauhut

    2008-12-01

    Full Text Available The fossil record of archosaurs - crocodylomorphs, pterosaurs and dinosaurs - from the Jurassic of the Southern Hemisphere is critically reviewed, and its evolutionary implications are evaluated. Although several important faunas and also isolated finds are known from Gondwana, the record in total is still very patchy, and any evolutionary scenario based on this record should be seen as tentative. Compared to the Northern Hemisphere, southern archosaurs are much more poorly known, which is especially true for terrestrial crocodiles and pterosaurs. Marine crocodiles are rather well represented in south-western South America, whereas the report of terrestrial archosaurs is currently best for Africa. However, in South America, important and especially promising archosaur faunas are known from the Callovian Cañadón Asfalto and the (?Tithonian Cañadón Calcáreo formations of Chubut province, Argentina. Early and Middle Jurassic Gondwanan archosaurs demonstrate that the faunas of that period still had a generally Pangean distribution, whereas first indications of differential archosaur evolution in the Northern and Southern Hemispheres are evident in Late Jurassic Gondwanan faunas.

  9. Argentina

    Directory of Open Access Journals (Sweden)

    Hernan Galperin

    2004-01-01

    Full Text Available En este trabajo se analizan las bases sobre las que se está desarrollando el proceso de transición hacia la TV digital en Brasil y Argentina, y se discuten las posibilidades que la transición presenta para replantear la estructura de mercado y el modelo de regulación de la TV abierta en los países del Mercosur. La principal hipótesis es que la TV digital abre una oportunidad única para reformar el actual modelo de radiodifusión basado en la concesión de un número reducido de licencias a operadores de tipo generalista. Al multiplicar la capacidad de transmisión y facilitar el desarrollo de servicios interactivos tanto de entretenimiento como educativos y de información, la transición a la TV digital se ofrece como instrumento de política pública para alcanzar objetivos clave en materia de comunicación, como el pluralismo, la apertura del mercado y el achicamiento de la llamada brecha digital.

  10. Argentina

    Directory of Open Access Journals (Sweden)

    G. Benedetti

    2007-01-01

    Full Text Available El presente trabajo tiene como objetivo realizar un diagnóstico ambiental de un sector de la ciudad de Bahía Blanca, Argentina basado en el arbolado urbano de alineación. El arbolado constituye un componente fundamental de los paisajes artifi ciales ya que contribuye al aumento del confort y al mejoramiento de la calidad del medio. En este sentido, actúa como un factor moderador de las condiciones climáticas, la contaminación y la salud de la población. El municipio de la ciudad de Bahía Blanca tiene como proyecto la realización de inventarios del arbolado en los distintos barrios, para lograr optimizar la relación entre la cantidad de ejemplares arbóreos y la densidad poblacional. Es importante considerar la variedad de ejemplares en función del uso del suelo y de las características ambientales de cada sector. Por lo tanto, este trabajo presenta un diseño metodológico para la elaboración del plano verde de la ciudad.

  11. Facies Architecture And Sequence Stratigraphy of Jurassic Tidal Successions in the Lajas Formation, Neuquen Basin, Argentina; an Outcrop Analogue For the Tilje Formation, Offshore Mid-Norway

    Energy Technology Data Exchange (ETDEWEB)

    McIlroy, D.; Flint, S.

    1999-07-01

    A common element of sequence stratigraphic models for ancient shallow marine systems is the switch from wave-dominated shoreface deposition during highstand to tidal/estuarine deposition within incised valleys which provide the necessary amplification of tidal currents, during lowstand/early base level rise. Thus, tide-dominated sedimentation is restricted to specific base level positions, which has important implications for reservoir geometry and quality. The Lajas Formation is studied as an analogue to the Jurassic Tilje Formation. The similar age, tectonic setting, sedimentology and aggradational nature of the tidal succession make the Lajas an ideal analogue with which to study facies architecture and test sequence stratigraphic models. This is especially so, since field data can be tied to geophysical data associated with producing oil fields. The lower Jurassic Lajas Formation of the Neuquen basin comprises 500 m of well-exposed tide-dominated sediments deposited as two low frequency unconformity-bounded sequences which are tide-dominated throughout.

  12. Remelting of Neoproterozoic relict volcanic arcs in the Middle Jurassic: Implication for the formation of the Dexing porphyry copper deposit, Southeastern China

    Science.gov (United States)

    Liu, Xuan; Fan, Hong-Rui; Santosh, M.; Hu, Fang-Fang; Yang, Kui-Feng; Li, Qiu-Li; Yang, Yue-Heng; Liu, Yongsheng

    2012-10-01

    The Dexing copper deposit in southeastern China is a typical non-arc porphyry deposit, the origin of which has been a topic of debate for several decades. Here we present new results from U-Pb geochronology, whole-rock chemistry and Sr-Nd-Hf-O isotopic investigations on the ore-forming granodioritic porphyry. LA-ICPMS zircon U-Pb data suggest that the granodioritic porphyry was formed in the Middle Jurassic (ca. 172.5 Ma) probably associated with lithospheric thinning driven by either sub-continental lithospheric mantle delamination or asthenospheric upwelling. The porphyry displays both arc-like and adakitic trace element signatures. The adakitic features suggest that HREE (heavy rare earth elements)-rich minerals such as garnet and hornblende, in the absence of plagioclase resided in the source region. The arc-like signatures are broadly comparable with those of the proximal Neoproterozoic island arc rocks including the keratophyre from Shuangxiwu Group and associated granitoids indicating a potential genetic relationship. The porphyry has chondritic ɛNd(t) of - 0.28 to 0.25 and radiogenic ɛHf(t) of 2 to 7, and correspondingly, uniform two stage depleted mantle Nd model ages of 940-980 Ma and Hf model ages of 800-1100 Ma (mean ~ 920 Ma). On Nd and Hf isotopic evolution diagrams, these values are markedly similar to those of the adjacent Neoproterozoic arc rocks when calculated forward to the Mid-Jurassic. Zircons of the porphyry show mantle-like oxygen isotope characters with δ18O values clustering in the range of 4.7-5.9‰, similar to the values for the Neoproterozoic arc rocks mentioned above. The geochemical and isotopic features recorded in our study suggest mantle-derived magmas with no significant supracrustal input for the source of the porphyry. With regard to the source of the Cu ore, we consider a model involving the remelting of sulfide-bearing arc-related lower crustal source. Furthermore, the occurrence of a Neoproterozoic VMS (volcanic massive

  13. The Jurassic of Denmark and Greenland: The use of spectral natural gamma-ray analysis in reservoir evaluation of siliciclastic sediments: a case study from the Middle Jurassic of the Harald Field, Danish Central Graben

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    Fabricius, Ida L.

    2003-10-01

    Full Text Available A cored sandstone interval from the Middle Jurassic Harald Field of the Danish North Sea was chosen for an investigation of the mineralogical sources for the gamma-ray activity, and with the purpose of determining how the Spectral Natural Gamma (SNG log could be used as an indicator of reservoir quality. Core intervals of quartz arenites and quartz wackes were selected. Although no linear relationship was found between clay content and potassium (K, thorium (Th, or uranium (U, the K content characterises three discrete lithofacies. Lithofacies I has a grain-supported texture, with a predominance of quartz grains; only minor fine-grained matrix is present. Sandstones of lithofacies I have a low K content and most of the K is hosted in feldspar. Porosity varies between 23% and 28% and permeability is in the range 200-2000 mD. Lithofacies II sandstones have a grain-supported texture, with a predominance of quartz grains; fine-grained matrix fills the intergranular volume. Sandstones of lithofacies II have an intermediate K content, with K-feldspar, mica, and illite as the main sources. Porosity varies between 11% and 17% and permeability is in the range 0.4-25 mD. Lithofacies III has a matrix-supported texture with quartz grains floating in a clay-rich matrix. Samples from lithofacies III have the highest K signal. Illite and illitised kaolinite are roughly equal in importance as sources of K. Porosity is up to 11% and permeability up to 0.5 mD. The Th and U content of all lithofacies is governed primarily by the presence of heavy minerals; no apparent general relationship between U and Total Organic Carbon (TOC was found. Comparisons between the core measurements of K, Th, and U, and the SNG log disclosed a discrepancy between the calibrations of laboratory and borehole measurements. For U the discrepancy contains an erratic element, whereas the difference for K and Th can be eliminated by correction factors. Thus, the conclusions based on

  14. Unexpected skeletal histology of an ichthyosaur from the Middle Jurassic of Patagonia: implications for evolution of bone microstructure among secondary aquatic tetrapods

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    Talevi, Marianella; Fernández, Marta S.

    2012-03-01

    During the Mesozoic, one of the most significant evolutionary processes was the secondary adaptation of tetrapods to life in water. Several non-related lineages invaded from the terrestrial realms and from the oceans of the entire world. Among these lineages, ichthyosaurs were particularly successful. Advance parvipelvian ichthyosaurs were the first tetrapods to evolve a fish-shaped body profile. The deep skeletal modifications of their bodies, as well as their biology, depict advance ichthyosaurs as the paradigm of secondary adaptation of reptiles to marine life. Functional inferences point to them as off-shore cruising forms, similar to a living tuna, and some of them were capable of deep diving. Bone histology of some genera such as Temnodontosaurus, Stenopterygius, Ichthyosaurus, and Caypullisaurus, characterized by overall cancellous bone, is consistent with the idea of a fish-shaped ichthyosaurs as fast and far cruisers. Here, we provide histological examination of the ribs of the Middle Jurassic parvipelvian Mollesaurus. Contrasting with the bone histology of other parvipelvian, Mollesaurus ribs are characterized by a compact and thick cortex. Our data indicate that the rib cage was heavy and suggest that not all advanced ichthyosaurs were fast cruisers. The compact and dense ribs in these parvipelvian show that advance ichthyosaurs were ecologically more diverse than previously thought and that the lightening of the skeleton reversed, as also occurred in the evolution of cetacean, at least once along the evolutionary history of ichthyosaurs.

  15. Facies analysis of an ancient, dismembered, large caldera complex and implications for intra-arc subsidence: Middle Jurassic strata of Cobre Ridge, southern Arizona, USA

    Science.gov (United States)

    Riggs, Nancy R.; Busby-Spera, Cathy J.

    1991-11-01

    The Middle Jurassic (˜ 170 Ma) Cobre Ridge caldera is an elongate caldera complex that formed during the eruption of the tuff of Pajarito, a crystal-rich rhyodacite ignimbrite with an estimated volume > 1000 km 3. The caldera subsided in two subequal blocks: to the southeast, caldera-forming ignimbrite is as much as 3000 m thick, whereas the northwest half of the caldera subsided to lesser depths during the initial eruption, but was the locus of subsidence during subsequent eruptions, providing a depocenter for a > 1.5 km-thick section of secondary- and post-collapse volcanic and sedimentary strata. These strata record moat formation and filling and waning volcanism, including: (1) areally restricted ignimbrites up to several tens of meters thick that may have been ponded between caldera margins and/or fault scarps; (2) a ⩾ 600 m-thick ignimbrite whose eruption probably caused further collapse of the caldera or enlargement of the caldera margins; (3) a localized debris apron deposit up to 500 m thick that represents material reworked from intra-caldera pyroclastic deposits and possibly caldera walls; and (4) eolian and fluvial sandstones and water-lain tuffs. Megabreccia blocks as large as 0.5 km along strike probably demarcate approximate caldera margins, suggesting that the composite caldera was approximately 50 km long by 25 km wide. The preserved thickness of the strata of Cobre Ridge ( > 4500 m) is greater than many ancient continental volcanic sequences, suggesting external (i.e. tectonic) controls on subsidence, but preservation of this great thickness of strata is apparently due entirely to volcanic subsidence.

  16. Middle Jurassic Sporo-pollen Assemblages in Northern Turpan Depression, Xinjiang, Northwest China%吐鲁番拗陷北部中侏罗世孢粉植物群

    Institute of Scientific and Technical Information of China (English)

    尹凤娟; 张子福

    2002-01-01

    Eighty-one species of fossil spores and pollen assigned to 52 genera are found from the Middle Jurassic Xishanyao,Sanjianfang and Qiketai Formations of boreholes Le 1, Mi 1, Shan 1 and Dun 1 in the northern Turpan Depression, Xinjiang, northwest China. Three assemblages have been proposed as: Cyathidites-Psophosphaera-Cycadopites assemblage, Cyathidites-Quadraeculina-Classopollis assemblage and Cyathidites-Callialasporites-Classopollis assemblage obtained from the Xishanyao Formation, the Sanjianfang Formation and Qiketai Formation respectively. Based on the sporo-pollen assemblage features and correlation,their geological ages are regarded as of Middle Jurassic,probably Aalenian to Bathonian.The results of the study indicate that the vegetation of early Middle Jurassic in this region consisted mainly of Gymnospermae of Ginkgoaceae of Cycadales, Podocarpaceae, Pinaceae and Pteridophyta of Cyatheaceae, Osmundaceae, Lycopodiaceae and Dicksoniaceae, etc. They reflect a warm-moist subtropic climate.To the middle-late Middle Jurassic, Cheirolepidaceae was dominant in the vegetation, which indicates that the climate was in the trend of becoming dry.%报道了新疆吐鲁番拗陷北部勒1、米1 、山1和墩1井中侏罗世孢粉化石52属81种.建立了本区中侏罗世孢粉组合: Cyathidites-Psophosphaera-Cycadopite 组合、 Cyathidites-Quadraeculina-Classopollis 组合和 Cyathidites-Callialasporites-Classopollis 组合.它们分别产自西山窑组、三间房组和七克台组.根据孢粉组合特征及其对比, 认为3个组合的地质时代属阿林-巴通期.经研究表明, 中侏罗世早期的植被是以银杏、苏铁类和松柏类等乔木为主体, 并伴有桫椤科树蕨及紫萁科和卷柏科等草本植物.古气候应属温暖潮湿的亚热带气候.至中侏罗世中晚期, 掌鳞杉科植物在植被中占主导地位, 指示当时的气候趋于干旱.

  17. Sedimentology and palaeontology of the Upper Jurassic Puesto Almada Member (Cañadón Asfalto Formation, Fossati sub-basin), Patagonia Argentina: Palaeoenvironmental and climatic significance

    Science.gov (United States)

    Cabaleri, Nora G.; Benavente, Cecilia A.; Monferran, Mateo D.; Narváez, Paula L.; Volkheimer, Wolfgang; Gallego, Oscar F.; Do Campo, Margarita D.

    2013-10-01

    Six facies associations are described for the Puesto Almada Member at the Cerro Bandera locality (Fossati sub-basin). They correspond to lacustrine, palustrine, and pedogenic deposits (limestones); and subordinated alluvial fan, fluvial, aeolian, and pyroclastic deposits. The lacustrine-palustrine depositional setting consisted of carbonate alkaline shallow lakes surrounded by flooded areas in a low-lying topography. The facies associations constitute four shallowing upward successions defined by local exposure surfaces: 1) a Lacustrine-Palustrine-pedogenic facies association with a 'conchostracan'-ostracod association; 2) a Palustrine facies association representing a wetland subenvironment, and yielding 'conchostracans', body remains of insects, fish scales, ichnofossils, and palynomorphs (cheirolepidiacean species and ferns growing around water bodies, and other gymnosperms in more elevated areas); 3) an Alluvial fan facies association indicating the source of sediment supply; and 4) a Lacustrine facies association representing a second wetland episode, and yielding 'conchostracans', insect ichnofossils, and a palynoflora mainly consisting of planktonic green algae associated with hygrophile elements. The invertebrate fossil assemblage found contains the first record of fossil insect bodies (Insecta-Hemiptera and Coleoptera) for the Cañadón Asfalto Formation. The succession reflects a mainly climatic control over sedimentation. The sedimentary features of the Puesto Almada Member are in accordance with an arid climatic scenario across the Upper Jurassic, and they reflect a strong seasonality with periods of higher humidity represented by wetlands and lacustrine sediments.

  18. A NEW SPECIES OF OMEISAURUS FROM THE MIDDLE JURASSIC OF ZIGONG, SICHUAN%四川自贡中侏罗世峨眉龙一新种

    Institute of Scientific and Technical Information of China (English)

    江山; 李飞; 彭光照; 叶勇

    2011-01-01

    记述了产自四川自贡大山铺中侏罗世峨眉龙属一新种--焦氏峨眉龙(Omeisaurus jiaoi sp.nov.).新种为大型蜥脚类恐龙,以如下特征区别于其他蜥脚类:前、中部背椎为典型的后凹型,后部背椎为双平型,背椎神经棘呈高大棒状,不分叉;尾椎为弱双凹型,第一尾椎不具扇形尾肋;第一脉弧短小且与第一尾椎关联;锁骨长大;肱骨和股骨细长而圆实;肱骨与股骨长度之比为0.83,尺骨与肱骨长度之比为0.72,胫骨与股骨长度之比为0.63.%Omeisaurus jiaoi, a new species of giant sauropod is described in this paper. The specimen (ZDM 5050) was discovered from the Xiashaximiao Formation of the Middle Jurassic of Zigong Dinosaur Museum, Sichuan.ZDM 5050 is a nearly complete skeleton. Its main features can be summarized as follows:dorsal vertebrae are tall and large. The anterior dorsal vertebrae (dorsals 1 to 6) are opisthocoelous. The pleurocoels of the dorsal vertebrate are well developed except on the 1st dorsal.The neural spines are club-like and the neural spines of the anterior dorsal vertebrae are not bifurcated. Caudal vertebrae are relatively short and thick. The anterior caudal vertebrae are slightly amphicoelous. The chevron of the lst caudal vertebrae is connected with the lst caudal and is shallow and small. Whereas the 1st caudal vertebrae of Omeisaurus tianfuensis have no chevron. The rib of the 1st caudal vertebrae are laterally directed, while the first caudal rib of the other species of Omeisaurus are prominently enlarged distally, being slightly fan-shaped.Humerus is long and straight, with slightly expanded proximal end and greatly expanded distal end. The deltopectoral crest is well-developed and relatively low. Femur is slender in shape,with greatly expanded proximal and distal ends. The fourth trochanter is well-developed. The ratio of the humerus to femur length is approximately 0. 83, the ratio of the ulna to humerus length is approximately 0.72, and

  19. 喀喇昆仑西部龙山组沉积环境及构造背景%Sedimentary environment and structural setting of Middle-Lower Jurassic Longshan Formation in the west of Kunlun Mountains of Gela, China

    Institute of Scientific and Technical Information of China (English)

    李振兴; 侯明才; 王约; 张杰; 康孔跃; 杜涛; 杨伟; 史俊波

    2013-01-01

    出露于新疆喀喇昆仑西部阿格勒达板沟伊力克附近的侏罗系龙山组,具丰富的沉积构造及清晰的沉积序列,是研究侏罗系沉积环境及构造演化进程的良好载体.通过对其岩石学、沉积学特征的研究,显示喀喇昆仑西部龙山组为海陆过渡环境的混合潮坪沉积产物;通过碎屑矿物的物源分析,揭示其物源来自再旋回的造山带;区域构造背景研究显示在早—中侏罗世,本区开始了由海向陆的转换进程.%The Jurassic Longshan Formation outcropping in the Agelendaba groove in the western Kunlun Mountains of Gela in Xinjiang is rich in sedimentary structures and clear sedimentary sequences. It is a good carrier to study the Jurassic sedimentary environment and tectonic evolution process. The research on the petrology and sedimentology characteristics shows that there are the mixed tidal flat deposition products in Longshan Formation. The analysis of the paralic environment detrital minerals provenance reveals that the sediments comes from the orogenic belts of the recyclings of and the study of the regional tectonic background show indicates that this area began the process of conversion from sea to land in the Early-Middle Jurassic.

  20. Jurassic fishes of Gondwana Peces jurásicos de Gondwana

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    Adriana López-Arbarello

    2008-12-01

    Full Text Available The Jurassic is an important period for understanding the origin of modern fish faunas, since it saw the first radiation - and in some cases the origin - of most modern groups. In chondrichthyans, neoselachian sharks and rays diversified during this time. In actinopterygians, the neopterygians, and among them the teleosts, experienced an important radiation, which led to the appearance of several of the modern teleosts groups. In the sarcopterygians, dipnoans and actinistians approached their current forms. However, the Jurassic fossil record of fishes is strongly biased towards the Northern Hemisphere. The only notable Early Jurassic fish fauna from Gondwana is that of the Kota Formation of India. For the Middle Jurassic, the most important Gondwanan fish faunas are those of the Aalenian-Bathonian Stanleyville Beds of the Democratic Republic of Congo, in which a distinct freshwater and a marine fauna are found. In the Late Jurassic, the Gondwanan record is slightly better, with important marine faunas being known from the Oxfordian Quebrada del Profeta in Chile and the Tithonian Vaca Muerta Formation of Argentina. Freshwater faunas have been described from the Tithonian Talbragar Beds of eastern Australia and the Tithonian Cañadón Calcáreo Formation of Argentina. The taxonomic composition of the known marine actinopterygian faunas of Gondwana is in general agreement with faunas of the Northern Hemisphere. However, the Jurassic fish record from Gondwana is highly incomplete both stratigraphically and geographically, and most faunas are in need of revision, further hampering an interpretation of Jurassic fish evolution in the Southern Hemisphere.El Período Jurásico es muy importante para entender el origen de las ictiofaunas modernas, dado que evidenció la primera radiación - y en algunos casos el origen - de la mayoría de los grupos modernos. Así, los condrictios neoselacios se diversificaron durante este periodo. Los actinopterigios

  1. Using dental enamel wrinkling to define sauropod tooth morphotypes from the Canadon Asfalto Formation, Patagonia, Argentina.

    Directory of Open Access Journals (Sweden)

    Femke M Holwerda

    Full Text Available The early Middle Jurassic is regarded as the period when sauropods diversified and became major components of the terrestrial ecosystems. Not many sites yield sauropod material of this time; however, both cranial and postcranial material of eusauropods have been found in the Cañadón Asfalto Formation (latest Early Jurassic-early Middle Jurassic in Central Patagonia (Argentina, which may help to shed light on the early evolution of eusauropods. These eusauropod remains include teeth associated with cranial and mandibular material as well as isolated teeth found at different localities. In this study, an assemblage of sauropod teeth from the Cañadón Asfalto Formation found in four different localities in the area of Cerro Condor (Chubut, Argentina is used as a mean of assessing sauropod species diversity at these sites. By using dental enamel wrinkling, primarily based on the shape and orientation of grooves and crests of this wrinkling, we define and describe three different morphotypes. With the exception of one taxon, for which no cranial material is currently known, these morphotypes match the local eusauropod diversity as assessed based on postcranial material. Morphotype I is tentatively assigned to Patagosaurus, whereas morphotypes II and III correspond to new taxa, which are also distinguished by associated postcranial material. This study thus shows that enamel wrinkling can be used as a tool in assessing sauropod diversity.

  2. Geochemistry of a Tidal Transgressive Heterolithic Succession:The Ituzaingo Formation (Middle Miocene),Argentina

    Institute of Scientific and Technical Information of China (English)

    POBERTOTORRA

    2000-01-01

    Geochemical analysis by means of XRF and ICP-AES was carried out on 35 selected saples,Major and trace elements were determined.They were:CaCO3,P2O5,Fe2Oe,TiO2,SiO2,Al2O3,CaO,K2O,MnO,Rb,Cs,Ga,Zr,Ta,Nb,Sr,Ba,Cr,Ni,Zn,Pb,Cu,V and B.The country rocks studied were of sandy-muddy lithofacies.belonging to a typical tide marine transgressive heterolithic succession of Middle Miocee age.They are called the Ituzatingo Formation.The formation outcrops in northeastern Argentina on the left of the Parana River Valley.The depositional setting largely depends on the outstanding internal structures and textures(i.e.,herringbone cross stratification,tidal bindles,reactivation surfaces).In the study area.loessial friable sediment was used as geochemical background because it overlies shallow marine sediments.The results show significant differences.Boron is absent in loessial sediments.On the other hand .several trace elements such as vanadium and chromium are concentrated in the shallow marine sediments.These results may be useful to discernuncertain beds in the area studied.

  3. Overview of the geochemistry and Rb/Sr, Sm/Nd isotopes of Middle Jurassic and Tertiary granitoid intrusions: a new insight on tectono-magmatism and mineralization of this period in Iran

    Directory of Open Access Journals (Sweden)

    Mohammad Ali Jazi

    2012-10-01

    Full Text Available One of the most intensive occurrences of magmatism in Iran was in the middle Jurassic period. Among the granitoid intrusions in this period as discrete bodies or complexes can be pointed to Aligoodarz, Alvand, Astaneh, Boroujerd, Malayer, and Chah-Dozdan in the Sanandaj-Sirjan zone; Shir-kuh and Ayrakan in the Central Iran zone; Shah-kuh, Sorkh-kuh and Kalateh-Ahani in the Lut Block. These granitoids are mostly peraluminous and belong to high-K calc-alkaline series. CaO/Na2O ratios (0.12 to 8.37 mostly suggest a clay-free source for formation of the intrusive rocks magma. Chondrite-normalized Rare Earth Elements (REEs diagram do not display high enrichment of Light Rare Earth Elements (LREEs than Heavy Rare Earth Elements (HREEs and general pattern is relatively flat. In addition, diagram shows Eu negative anomaly, which can be attributed to indicate reducing conditions in formation of magma and/or magma derived from plagioclase depth as source. The lower continental crust-normalized spider diagram indicates enrichment in LILE (Rb, Cs, and K and LREE (La and Ce and depletion in Ba, Nb, Ta, Sr, and Ti. Initial 87Sr/86Sr ratios are 0.70609 to 0.71938 and initial εNd values are negative (from -6.51 to -1.1 indicating that magma derived from continental crust. Geochemical and isotopic evidence of the intrusive rocks shows continental crust origin (S-type granitoid and due to continental collision. Geological findings such as stop in sedimentation, regional metamorphism, ophiolite displacement, and continental collision-related mineralization confirm continental collision between Iranian and Arabian plates in the Middle Jurassic period.

  4. Mesozoic Coleopteran Faunas from Argentina: Geological Context, Diversity, Taphonomic Observations, and Comparison with Other Fossil Insect Records

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    María Belén Lara

    2012-01-01

    Full Text Available The order Coleoptera is the most diversified group of the Class Insecta and is the largest group of the Animal Kingdom. This contribution reviews the Mesozoic insects and especially the coleopteran records from Argentina, based on bibliographical and unpublished materials (86 described species, 526 collected specimens. The material came from different geological units from the late Middle Triassic to the Late Triassic (Bermejo, Cuyo, and Malargüe basins to the Middle-Late Jurassic and Early Cretaceous (Deseado Massif, Cañadón Asfalto, and San Luís Basin. The coleopteran record is composed of 29 described species with 262 collected specimens (isolated elytra mainly represented by Triassic species and only four specimens recorded in Jurassic units, all of them currently unpublished. These fossil coleopterans provide fundamental information about the evolution of insects in the Southern Hemisphere and confirm the Triassic Argentinean insect deposits to be among the most important in the world.

  5. Preandean geological configuration of the eastern North Patagonian Massif, Argentina

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    Daniel A. Gregori

    2013-11-01

    Full Text Available The Preandean geological configuration of the eastern North Patagonian Massif is established through the use of geological and geophysical analysis. The positive gravity anomalies located near the Atlantic coast are due to 535 and 540 Ma old rocks belonging to the Pampean Orogeny (Precambrian–middle Cambrian, which are widely recognized in central and northern Argentina. The Famatinian Cycle (Ordovician–Devonian is represented by a Silurian–Devonian marine basin equivalent to those of eastern-central Argentina and South Africa, and which was deformed at the end of the Devonian by an ∼E–W to WNW–ESE compressional event, part of the Famatinian Orogeny. Containing strong gravity gradients, the NW–SE belt is coincident with fault zones which were originated during the Gondwanide Orogeny. This event also produced NW–SE overthrusting of the Silurian–Devonian sequences and strike-slip faults that displaced blocks in the same direction. This deformation event belongs to the Gondwanide Orogeny that includes movements related to a counterclockwise rotation of blocks in northern Patagonia. The strong negative anomalies located in the western part of the area stem from the presence of rocks of the Jurassic Cañadón Asfalto basin interbedded in the Marifil Complex. These volcaniclastic sequences show mild deformation of accommodation zones in a pre-Jurassic paleorelief.

  6. The discovery of Middle Jurassic volcanic rocks in north-ern Fujian Province and its geological significance%闽北地区中侏罗世火山岩的发现及其地质意义

    Institute of Scientific and Technical Information of China (English)

    李亚楠; 邢光福; 邢新龙; 陈世忠; 段政; 杨东; 胡凌云

    2015-01-01

    There are only very few Middle Jurassic volcanic rocks exposed along the southeast coast of China, but they are very im-portant for the study of the regional Mesozoic tectonic magmatic activiy and tectonic evolution. The authors discovered for the first time the Middle Jurassic volcanic rocks in the Tieshan area of Zhenghe during the survey of large area of Cretaceous volcanic rocks in northern Fujian Province. The zircon U-Pb age obtained by LA-ICP-MS technique is 173.63 ± 0.80Ma. The volcanic rocks are welded tuff, belonging to the calc-alkaline series. Geochemical data show that they are peraluminous rocks rich in potassium and large ion lithophile elements but poor in high field strength elements. Therefore, these rocks must have been formed in a continental margin arc environment, related to the subduction of the paleo-Pacific plate.%中侏罗世火山岩在东南沿海分布极少,但对区域中生代构造-岩浆活动过程及大地构造演化的研究具有重要意义.在闽北地区大面积白垩纪火山岩区调查中,在政和铁山地区发现中侏罗世火山岩,用LA-ICP-MS同位素测试技术测得的锆石U-Pb年龄为173.63±0.80Ma.火山岩属钙碱性系列流纹质熔结凝灰岩,显示过铝质、富钾、富集大离子亲石元素,亏损高场强元素等地球化学特征,推断其形成于陆缘弧环境,与古太平洋板块早期俯冲作用有关.

  7. Middle Jurassic Yanan Formation Sequence Stratigraphic Well Logging Response Characteristics in Ningdong Coalfield%宁东煤田中侏罗纪延安组层序地层测井响应特征

    Institute of Scientific and Technical Information of China (English)

    冯希文

    2012-01-01

    以钻井、测井资料为基础,以高分辨率层序地层学为指导,通过层序界面和层序地层的测井响应特征研究,对宁东煤田中侏罗纪延安组含煤岩系进行了精细划分与对比.结果表明,宁东煤田中侏罗纪延安组层序地层界面位于测井曲线基值发生明显改变的转折点上,大型河道冲刷面、湖泛面以及进积(加积)与退积的相互转换面也是层序界面的发育位置;层序地层的测井响应特征中,进积类型测井曲线呈现漏斗型,退积类型测井曲线呈现钟形,加积类型测井曲线呈现箱型;宁夏宁东煤田中侏罗纪延安组可以识别出3个三级层序,共识别出9个层序组,并可进一步详细划分为9个四级层序.%Based on drilling and well logging data, guiding by the high resolution sequence stratigraphy, studied sequence boundary and sequence stratigraphic well logging response characteristics, carried out refined division and correlation of middle Jurassic Yanan Formation coal-bearing strata in the Ningdong coalfield. The result has demonstrated that the Yanan Formation sequence stratigraphic boundaries used to be on the abrupt turning points of logging trace basic values; switching planes between surfaces of large sized channel scouring, lacustrine flooding, prograding (aggrading) and retrograding also the developing places of stratigraphic boundaries. In sequence stratigraphic well logging response characteristics, prograding typed logging traces present infundibuliform, while retrograding campaniform and aggrading box-form. 3 third-order sequences, 9 sequence sets can be identified in middle Jurassic Yanan Formation in Ningdong coalfield in Ningxia, and then can be further subdivided into 9 fourth-order sequences.

  8. Middle Jurassic MORB-type gabbro, high-Mg diorite, calc-alkaline diorite and granodiorite in the Ando area, central Tibet: Evidence for a slab roll-back of the Bangong-Nujiang Ocean

    Science.gov (United States)

    Yan, Haoyu; Long, Xiaoping; Wang, Xuan-Ce; Li, Jie; Wang, Qiang; Yuan, Chao; Sun, Min

    2016-11-01

    Mesozoic intrusions, including MORB-type gabbros, high-Mg diorites, calc-alkaline diorites and granodiorites, were exposed in the Ando microcontinent that is bounded between the Qiangtang and Lhasa terranes. Discoveries of these Mesozoic intrusions have provided new petrogenetic constraints on our understanding of Bangong-Nujiang ocean evolution. Zircon U-Pb dating shows that these intrusions formed in the early-middle Jurassic (174-177 Ma). The gabbros have relatively flat REE distribution patterns, which is analogous to the geochemical features of MORB. Their positive εNd(t) values (εNd(t) = 4.4-5.5) are consistent with those of ophiolites along the Bangong-Nujiang suture zone. These gabbros are also characterized by enrichments of fluid-sensitive elements and negative to positive Nb anomalies, indicative of the influence of subduction-related compositions in their mantle source. These features suggest that the gabbros were most likely originated from asthenosphere-derived melts metasomatized by enriched lithospheric mantle during the upwelling. The high-Mg diorites are characterized by typical features of high compatible elements (MgO = 8.3-10.24 wt%, Cr = 400-547 ppm, Ni = 120-152 ppm), high Mg# (70-74) and low Sr/Y ratios. Their high initial 87Sr/86Sr isotopic ratios and negative εNd(t) values (- 10.5 to - 10.8), together with their sanukitic characteristics, imply that the high-Mg diorites were probably produced by partial melting of mantle peridotites metasomatized by slab-derived melts and aqueous fluids. The calc-alkaline diorites have relatively high MgO (4.04-5.50 wt%), Cr, Ni contents and Mg# (56-59), as well as high (86Sr/87Sr)i ratios and negative εNd(t) values (- 7.5 to - 7.3), suggesting that they were most likely formed by partial melting of the Ando basement rocks with significant input of mantle components. The granodiorites are peraluminous and have higher (86Sr/87Sr)i ratios and more negative εNd(t) values (- 10.6 to - 10.8), similar to

  9. Jurassic Amber in Lebanon

    Institute of Scientific and Technical Information of China (English)

    Dany AZAR; Raymond G(E)ZE; Antoine EL-SAMRANI; Jacqueline MAALOULY; André NEL

    2010-01-01

    Reports of amber predating the Lower Cretaceous are unusual and scarce; they mostly refer to amber pieces of millimetric dimension.In the present study,we report the discovery of 10 new outcrops of Jurassic amber in Lebanon.Some of these had large centimetric-sized pieces of amber.The new localities are described,amber is characterized,and its infrared spectra given.Although the new Jurassic amber yielded to date no more than fungal inclusions,this material is significant and promising.The discovery of several Jurassic outcrops provides crucial information on the prevailing paleoenvironment of that time.

  10. Vulnerability Factors in the Middle Class: Evidence for Argentina and Mexico after the Crisis of the 1990s

    Directory of Open Access Journals (Sweden)

    Gabriela Liliana Galassi

    2012-01-01

    Full Text Available Este trabajo explora el perfil de la clase media argentina y la mexicana durante las últimas crisis en ambos países. Se combinan las miradas de vulnerabilidad social y análisis de clase, subyaciendo teóricamente una "matriz vulnerabilidad-clases sociales". El análisis emplea las encuestas de hogares de Argentina para 1998 y 2003 y México, 1994 y 1996. Se observa que mientras la clase media mexicana se vio principalmente afectada durante la crisis llamada "efecto tequila" vía sus activos físicos (condiciones habitacionales, en Argentina la educación y el mercado laboral fueron los principales mecanismos afectados por la crisis de 2001.

  11. Using dental enamel wrinkling to define sauropod tooth morphotypes from the Cañadón Asfalto Formation, Patagonia, Argentina.

    Science.gov (United States)

    Holwerda, Femke M; Pol, Diego; Rauhut, Oliver W M

    2015-01-01

    The early Middle Jurassic is regarded as the period when sauropods diversified and became major components of the terrestrial ecosystems. Not many sites yield sauropod material of this time; however, both cranial and postcranial material of eusauropods have been found in the Cañadón Asfalto Formation (latest Early Jurassic-early Middle Jurassic) in Central Patagonia (Argentina), which may help to shed light on the early evolution of eusauropods. These eusauropod remains include teeth associated with cranial and mandibular material as well as isolated teeth found at different localities. In this study, an assemblage of sauropod teeth from the Cañadón Asfalto Formation found in four different localities in the area of Cerro Condor (Chubut, Argentina) is used as a mean of assessing sauropod species diversity at these sites. By using dental enamel wrinkling, primarily based on the shape and orientation of grooves and crests of this wrinkling, we define and describe three different morphotypes. With the exception of one taxon, for which no cranial material is currently known, these morphotypes match the local eusauropod diversity as assessed based on postcranial material. Morphotype I is tentatively assigned to Patagosaurus, whereas morphotypes II and III correspond to new taxa, which are also distinguished by associated postcranial material. This study thus shows that enamel wrinkling can be used as a tool in assessing sauropod diversity.

  12. Escuela media y abandono escolar en Argentina: aproximaciones a un debate pendiente Middle school and dropout in Argentina: approaches to an unresolved debate

    Directory of Open Access Journals (Sweden)

    Analia Otero

    2011-12-01

    Full Text Available Este texto tiene como objetivo exponer panorámicamente un recuento del surgimiento histórico de la educación media en Argentina, para avanzar luego en la evolución de la expansión matricular hasta la actualidad, contemplando los rasgos fundamentales de la misma. A partir de allí, se expondrán factores incidentes en la problemática del abandono escolar, prestando énfasis a las características de la modalidad técnica. Se retomarán puntos centrales de un debate escasamente explorado que es aquel que aborda la intersección específica entre abandono escolar y los estudiantes de modalidad técnica. Se subraya que las condiciones del mercado laboral actual, como la amplitud de la precarización, el avance del sector servicios y la estrechez en materia de industrialización tornan aún más acuciante el contorno de discusiones sobre esta problemática. Este panorama marcha en paralelo a cambios de envergadura en el sistema educativo nacional, enmarcados en sucesivas modificaciones a las normativas jurídicas que lo orientan.This text aims to expose panoramically a recount of the historical emergence of secondary education in Argentina, to advance later in the evolution of the expansion currently watching enrolling until the fundamental features of it. From there, it will expose the factors which affect the dropout problem giving particular emphasis to the characteristics of the technical arrangement. Focal points will resume in a little explored that debate is one that addresses the specific intersection between ESL students and technical arrangement. It emphasizes that current labor market conditions, as the amplitude of the precarious, the advance of the service sector and the narrowness in industrialization becomes even more pressing the outline of discussions on this issue. Panorama marching in parallel with major changes in the national education system, surrounded by successive amendments to legal regulations that guide the system.

  13. SICILIAN JURASSIC PHYSIOGRAPHY AND GEOLOGIC REALMS (ITALY

    Directory of Open Access Journals (Sweden)

    BENEDETTO ABATE

    2004-03-01

    Full Text Available Two tectono-sedimentary domains, which were deformed during the Neogene and evolved into two large structural sectors, characterize the Sicilian Jurassic: the Maghrebides and Peloritani. Africa margin sediments, passing downward to Triassic successions and perhaps originally to Paleozoic deposits, characterize the former. The latter belongs to the European "Calabrian Arc", where the Jurassic transgressively rests on a continental substrate (i.e. the crystalline Variscan basement. These domains are characterized by four sedimentary facies: shallow platform-derived limestones; condensed seamount-type red limestones; nodular limestones with ammonites; deep radiolarites and shales. These facies are illustrated in a dozen of stratigraphic logs. The drowning of most Triassic-Liassic carbonate platforms or ramps and the deepening of adjacent basins came with inferred Jurassic strike-slip tectonics, connected to the relative movement of Africa (Gondwanan part vs Europe (Laurasian part; the same strike-slip tectonics may have caused scattered intraplate volcanic seamounts found in Maghrebides. During the Jurassic the Maghrebide realm was characterized by the interfingering of basins and carbonate platforms. During the Early and Middle Liassic, carbonate platforms and ramps were dominant. Since Toarcian either radiolarites in some basins or Ammonite-bearing calcareous muds developed with intervening basaltic flows, and were accompanied by condensed pelagic carbonates on the ensialic seamount-type highs. The Peloritani realm displays similar characteristics, but with later transgression on the basement, several strike-slip basins and without any volcanoes.

  14. First fossil record of Discocephalinae (Insecta, Pentatomidae): a new genus from the middle Eocene of Río Pichileufú, Patagonia, Argentina

    Science.gov (United States)

    Petrulevičius, Julián F.; Popov, Yuri A.

    2014-01-01

    Abstract A new genus and species of Discocephalini, Acanthocephalonotum martinsnetoi gen. n. et sp. n. is described from Río Pichileufú, middle Eocene of Patagonia, Argentina at palaeolatitude ~ 46°S. The new species is the first fossil representative of the Discocephalinae. This taxon is extant in equatorial to subtropical America, and some species reach warm temperate latitudes (Buenos Aires province). The new genus is distinguished from the other genera of Discocephalini by the combination of these characters: interocular width greater than head length; head massive and quadrangular with the anterior margin almost straight; juga touching each other; labrum thick and curved; triangular ante-ocular process extending beyond the eye; broad spine-like antero-lateral process of the pronotum; pronotum explanate and bean shaped; scutellum triangular with a circular tongue reaching the anterior side of abdominal segment 7; and wings well developed with membrane just surpassing end of abdomen. PMID:25061387

  15. Temporal patterns in disparity and diversity of the Jurassic ammonoids of southern Germany

    Directory of Open Access Journals (Sweden)

    M. S. Simon

    2011-02-01

    Full Text Available A morphometric analysis of the characteristic whorl cross-sections of 1,200 Jurassic ammonoid species from southern Germany enabled us to characterise their morphospace. The successive Jurassic ammonoid faunas of southern Germany show characteristic patterns in morphospace occupation. While Early and Middle Jurassic ammonoids occupy limited areas of the morphospace range, the Late Jurassic ammonoids cover the entire spectrum. The ammonoids are characterised by an overall increase of both taxonomic diversity and morphological disparity in the course of the Jurassic. Strong fluctuations occur until the middle Late Jurassic, followed by a diversity decrease in the early Kimmeridgian and a disparity reduction in the early Tithonian. While diversity and disparity show similar progression during most of the Early Jurassic, they diverge subsequently and show only poor correlation until the end of the Jurassic. Particularly in the Middle Jurassic diversity and sea level changes correlate strongly. Neither temporal patterns in diversity nor disparity support the hypothesis of a mass extinction event in the early Toarcian. Significant changes in diversity and disparity in the early Callovian support a putative migration event of Boreal ammonoids into the Tethyan realm. doi:10.1002/mmng.201000016

  16. Geochemistry evidence for depositional settings and provenance of Jurassic argillaceous rocks of Jiyuan Basin, North China

    Indian Academy of Sciences (India)

    Yao Meng; Deshun Zheng; Minglong Li

    2017-02-01

    This paper aims to discuss the depositional settings and provenances for the Jurassic in Jiyuan basin, North China, based on the rare earth element (REE) and trace element features of 16 Jurassic argillaceous rock samples from the Anyao, Yangshuzhuang and Ma’ao Formations, respectively. Generally, geochemical analysis results show that chondrite-normalised REE distribution patterns of all the three formations are characterised by light-REE (LREE) enrichment, moderately negative Eu anomalies, slightly negative Ce anomalies, and strong fractionation between LREE and heavy-REE (HREE). Trace element proxies V/(V+Ni), Ceanom index, Ce/La, Sr/Ba, and Sr/Cu indicate a weak oxidation–reduction environment, progressively decreasing reducibility and water depth from the bottom up during Jurassic in Jiyuan basin. Palaeoclimate varied from humid in the Early Jurassic to arid in the Middle Jurassic, corresponding with the variations of palaeoredox and palaeosalinity. The provenances of Jurassic rocks in Jiyuan basin are mainly from felsic sources related to active continental margin and continental island arc. The Early–Middle Jurassic (Anyao and Yangshuzhuang Formations) provenances are mainly derived from North Qinling and partially from the eroded recycled felsic sedimentary covers of Taihang Mountain. In the late stage of Middle Jurassic (Ma’ao Formation), Taihang Mountain has been the primary source to Jiyuan basin. We conclude that the Jurassic rocks of Jiyuan basin reveal the progressive uplift and denudation processes of the Taihang Mountain.

  17. The Chachil Limestone (Pliensbachian-earliest Toarcian) Neuquén Basin, Argentina: U-Pb age calibration and its significance on the Early Jurassic evolution of southwestern Gondwana

    Science.gov (United States)

    Leanza, H. A.; Mazzini, A.; Corfu, F.; Llambías, E. J.; Svensen, H.; Planke, S.; Galland, O.

    2013-03-01

    New radiometric U-Pb ages obtained on zircon crystals from Early Jurassic ash layers found within beds of the Chachil Limestone at its type locality in the Chachil depocentre (southern Neuquén Basin) confirm a Pliensbachian age (186.0 ± 0.4 Ma). Additionally, two ash layers found in limestone beds in Chacay Melehue at the Cordillera del Viento depocentre (central Neuquén Basin) gave Early Pliensbachian (185.7 ± 0.4 Ma) and earliest Toarcian (182.3 ± 0.4 Ma) U-Pb zircon ages. Based on these new datings and regional geological observations, we propose that the limestones cropping out at Chacay Melehue are correlatable with the Chachil Limestone. Recent data by other authors from limestones at Serrucho creek in the upper Puesto Araya Formation (Valenciana depocentre, southern Mendoza) reveal ages of 182.16 ± 0.6 Ma. Based on these new evidences, we consider the Chachil Limestone an important Early Jurassic stratigraphic marker, representing an almost instantaneous widespread flooding episode in western Gondwana. The unit marks the initiation in the Neuquén Basin of the Cuyo Group, followed by widespread black shale deposition. Accordingly, these limestones can be regarded as the natural seal of the Late Triassic -earliest Jurassic Precuyano Cycle, which represents the infill of halfgrabens and/or grabens related to a strong extensional regime. Paleontological evidence supports that during Pliensbachian-earliest Toarcian times these limestones were deposited in western Gondwana in marine warm water environments.

  18. 藏北巴青中侏罗世Liostrea障积礁的发现%Discovery of the Middle Jurassic Liostreabarrier reefs at Baqên County, northern Tibet

    Institute of Scientific and Technical Information of China (English)

    肖传桃; 李世斌; 胡明毅; 龚文平; 肖安成; 林克湘; 张存善

    2001-01-01

    Middle Jurassic Liostrea barrier reefs were first discovered in the Biqu Formation, Maru, Baqên County, northern Tibet. According to reef-building organisms, Liostrea barrier reefs and Cyanobacteria-Liostrea binding-barrier reefs may be distinguished. They are mostly bed-like or bedded in shape. Every single reef is 4 to 8 m thick, with a cumulative thickness of 20 to 25 m. Liostrea is a solitary oyster-shaped bivalve animal with the left and right valves. The left valve shell bulges strongly, while the right valve shell is flat. Because this kind of organism lived with their left valve fixed to a substrate, they form the Liostrea community and Cyanobacteria-Liostrea community, representing a warm, clean normal neritic environment.%在藏北巴青县马如乡布曲组中发现中侏罗世Liostrea障积礁,据造礁生物不同可分为Liostrea障积礁和Cyanobacteria-Liostrea粘结—障积礁。它们多呈似层状和层状,单个礁体厚4~8m,累计总厚为20~25m。Liostrea是一种单体牡蛎状的双壳类动物,分为左右两瓣壳,左壳强烈膨凸,右壳扁平,系以左壳固着生活特化而成,在本区构成了Liostrea群落和Cyanobacteria-Liostrea群落,代表温暖、清洁的正常浅海环境。

  19. Exploring Jurassic Park.

    Science.gov (United States)

    Simmons, Patricia E.; Wiley, Clyde

    1993-01-01

    Describes several student-tested activities built around "Jurassic Park." The activities feature students engaged in role-playing scenarios, investigative research projects, journal writing and communications skills activities, cooperative learning groups, and learning experiences that make use of reading skills and mathematical knowledge. (PR)

  20. La Peligrosa caldera (47° 15‧S, 71° 40‧W): A key event during the Jurassic ignimbrite flare-up in Southern Patagonia, Argentina

    Science.gov (United States)

    Sruoga, P.; Japas, M. S.; Salani, F. M.; Kleiman, L. E.

    2014-01-01

    Pyroclastic and lava vent-facies, from the Late Jurassic El Quemado Complex, are described at the southern Lake Ghío, in the Cordillera Patagónica Austral. Based on the comprehensive study of lithology and structures, the reconstruction of the volcanic architecture has been carried out. Four ignimbrites and one rhyolitic lava unit, affected by oblique-slip normal faults have been recognized. The evolution of La Peligrosa Caldera has been modeled in three different stages:1) initial collapse, consisting of a precursory downsag subsidence, related to a dilatational zone, which controlled the location of the caldera, 2) main collapse, with the emplacement of large volume crystal-rich ignimbrites and megabreccias, under a progressive subsidence controlled by a pull-apart structure related to a transtensional regime and 3) post-collapse, in which lava flows and associated domes were emplaced under an oblique-extensional regime. The caldera records a remarkable change from transtension to oblique extension, which may represent an important variation in regional deformation conditions during Jurassic times. La Peligrosa Caldera may be considered a key event to understand the eruptive mechanisms of the flare-up volcanism in the Chon Aike Silicic Province.

  1. The geographic and phylogenetic position of sauropod dinosaurs from the Kota formation (Early Jurassic) of India

    Science.gov (United States)

    Gillette, David D.

    2003-03-01

    The earliest sauropods are the Late Triassic Isanosaurus from Thailand, the Early Jurassic Barapasaurus and Kotasaurus from the Kota Formation of the Pranhita-Godavari Basin of India and Vulcanodon from Zimbabwe, and a variety of Middle Jurassic genera from many localities in Gondwana and Laurasia except North America. These early sauropod genera are related, but their phylogenetic positions remain unresolved. Sauropods originated in Laurasia (Thailand and vicinity) or Pangea (broadly, Thailand, China, India), with at least three additional steps involving expansion and diversification through the Middle Jurassic.

  2. The Jurassic of Denmark and Greenland: The Jurassic of the Netherlands

    Directory of Open Access Journals (Sweden)

    Herngreen, G.F. Waldemar

    2003-10-01

    Full Text Available A recent revision of the lithostratigraphy of the Netherlands has triggered an extensive re-evaluation of existing ideas on the Jurassic structural and depositional history. Significant advances can be attributed to the incorporation of sequence stratigraphic concepts. In the course of the Triassic and Jurassic, structural complexity increased progressively. The Jurassic sedimentary succession can be subdivided into three depositional megasequences. Megasequence I (Rhaetian- Aalenian reflects the period between the so-called early and mid-Cimmerian tectonic phases. Megasequence II (Aalenian - Middle Callovian covers the period of activity of the mid-Cimmerian phase. Megasequence III (Middle Callovian - Ryazanian corresponds with the period between the mid-Cimmerian and late Cimmerian phases (particularly after pulse II. In this latter megasequence, six stages (IIIa-f are recognised. Sediments deposited during the Rhaetian and Ryazanian bear a stronger affinity with the Jurassic succession than with Triassic and Cretaceous sediments respectively. These stages are thus treated here as an integral part of the Jurassic succession. During the Rhaetian-Bajocian the area subsided relatively uniformly. A sheet of predominantly fine-grained marine sediments of great lateral uniformity was deposited. During the Toarcian, in particular, basin circulation was largely restricted. The cooling that followed the thermal Central North Sea dome uplift triggered an important extensional phase during the Aalenian-Callovian. The rift phase resulted in the formation of several smaller basins, each with its own characteristic depositional succession. The basins fall into three structural provinces: the eastern province (Lower Saxony Basin, E-W-striking; the northern province (Central Graben, N-S-striking; and the southern-central system (Roer Valley Graben - Broad Fourteens, with a strong NW-SE strike. The mid-Cimmerian event started to affect the Dutch basins during

  3. 内蒙古科尔沁右翼中旗上侏罗统满克头鄂博组木化石新资料%The new material of Upper Jurassic fossil woods found in the Manketouebo Formation of Horqin Right Wing Middle Banner, Inner Mongolia

    Institute of Scientific and Technical Information of China (English)

    付俊彧; 宋维民; 陶楠; 庞雪娇; 卞雄飞; 吴桐; 张志斌

    2012-01-01

    This paper reports the fossil woods found for the first time in the Jurassic volcanic-sedimentary strata in the central-southern part of the Da Hinggan Mountains. The fossils occur in the intermediate-acidic pyrodasu'c sedimentary rocks of the Manketouebo Formation in Horqin Right Wing Middle Banner of Inner Mongolia. According to detailed identification, there are S genera with 3 known and 2 unknown species. The main features of these fossils are described and their ages are discussed. A comprehensive analysis of the combinational features indicates that the fossil woods are middle stage of Late Jurassic in age. The newly found fossil woods provide new paleontologies] evidence for regional stratigraphic correlation of Upper Jurassic strata in the Da Hinggan Mountains region.%报道了首次在大兴安岭中南段侏罗系火山-沉积地层中发现的木化石.化石产于内蒙古自治区科尔沁右翼中旗地区满克头鄂博组中酸性火山碎屑沉积岩中,经沈阳地质矿产研究所张武研究员详细鉴定,有5属3个已知种和2个未定种.对新发现木化石的主要特征进行了描述,讨论了木化石的时代.综合分析所发现化石的组合特征,认为其时代属中晚侏罗世.这些木化石新材料为大兴安岭地区上侏罗统地层区域时比提供了新的古生物资料依据.

  4. Support for an “A-type” Pangea reconstruction from high-fidelity Late Permian and Early to Middle Triassic paleomagnetic data from Argentina

    Science.gov (United States)

    Domeier, Mathew; van der Voo, Rob; Tomezzoli, Renata N.; Tohver, Eric; Hendriks, Bart W. H.; Torsvik, Trond H.; Vizan, Haroldo; Dominguez, Ada

    2011-12-01

    A major disparity is observed between the late Paleozoic-early Mesozoic apparent polar wander paths (APWPs) of Laurussia and Gondwana when the landmasses are re-assembled in a conventional "A-type" Pangea. This discrepancy has endured from the earliest paleomagnetic reconstructions of the supercontinent, and has prompted discussions of non-dipole paleomagnetic fields and alternative paleogeographic models. Here we report on a joint paleomagnetic-geochronologic study of Late Permian and Early to Middle Triassic volcanic and volcaniclastic rocks from Argentina, which demonstrates support for an A-type model, without requiring modification to the geocentric axial dipole hypothesis. New SHRIMP U-Pb and 40Ar-39Ar isotopic dating has reinforced the inferred age of the sequences, which we estimate at ˜264 Ma (Upper Choiyoi Group) and ˜245 Ma (Puesto Viejo Group). Field-stability tests demonstrate that the volcanic rocks are carrying early/primary magnetizations, which yield paleopoles: 73.7°S, 315.6°E, A95: 4.1°, N: 40 (Upper Choiyoi) and 76.7°S, 312.4°E, A95: 7.3°, N: 14 (Puesto Viejo). A comprehensive magnetic fabric analysis is used to evaluate structural restorations and to correct for magnetization anisotropy. The paleomagnetic results derived from volcaniclastic rocks are interpreted to be affected by inclination shallowing, and corrections are discussed. A comparison of these new results with the existing Permian-Triassic paleomagnetic data from Gondwana suggests the presence of widespread bias in the latter. We contend that such bias can explain the observed APWP disparity, at least for Late Permian-Middle Triassic time, and that alternative paleogeographic reconstructions or non-dipole paleomagnetic fields do not need to be invoked to resolve the discrepancy.

  5. Relative growth and morphological sexual maturity size of the freshwater crab Trichodactylus borellianus (Crustacea, Decapoda, Trichodactylidae) in the Middle Paraná River, Argentina

    Science.gov (United States)

    Williner, Verónica; Torres, María Victoria; Carvalho, Débora Azevedo; König, Natalia

    2014-01-01

    Abstract The relative growth of a number of morphological dimensions of the South American freshwater crab Trichodactylus borellianus (Trichodactylidae) were compared and related to sexual dimorphism. Crabs were collected from ponds in the Middle Paraná River in Argentina. A regression model with segmented relationship was used to test for relative growth between these measurements where breakpoints infer the body size at which crabs reach sexual maturity. In both sexes the carapace width and the length, height, and thickness of the right and left chelae were measured, as well as the male pleopod length and the female abdomen width. All of these measurements were found to show positive allometry with the exception of the male pleopod length and the left chelae, which did not show a breakpoint. In females the breakpoint for the abdomen width inferred a morphological sexual maturity at carapace width 6.9 mm. In males the break point for the pleopod length was at carapace width 6.6 mm, with that for the chelae measurements was between carapace widths 6.4 and 6.9 mm. The relative growth pattern in Trichodactylus borellianus was found to be similar to that recorded for other species of the family Trichodactylidae. PMID:25561835

  6. Evidence for a Mid-Jurassic Adaptive Radiation in Mammals.

    Science.gov (United States)

    Close, Roger A; Friedman, Matt; Lloyd, Graeme T; Benson, Roger B J

    2015-08-17

    A series of spectacular discoveries have transformed our understanding of Mesozoic mammals in recent years. These finds reveal hitherto-unsuspected ecomorphological diversity that suggests that mammals experienced a major adaptive radiation during the Middle to Late Jurassic. Patterns of mammalian macroevolution must be reinterpreted in light of these new discoveries, but only taxonomic diversity and limited aspects of morphological disparity have been quantified. We assess rates of morphological evolution and temporal patterns of disparity using large datasets of discrete characters. Rates of morphological evolution were significantly elevated prior to the Late Jurassic, with a pronounced peak occurring during the Early to Middle Jurassic. This intense burst of phenotypic innovation coincided with a stepwise increase in apparent long-term standing diversity and the attainment of maximum disparity, supporting a "short-fuse" model of early mammalian diversification. Rates then declined sharply, and remained significantly low until the end of the Mesozoic, even among therians. This supports the "long-fuse" model of diversification in Mesozoic therians. Our findings demonstrate that sustained morphological innovation in Triassic stem-group mammals culminated in a global adaptive radiation of crown-group members during the Early to Middle Jurassic.

  7. Jurassic sedimentary evolution of southern Junggar Basin:Implication for palaeoclimate changes in northern Xinjiang Uygur Autonomous Region, China

    Institute of Scientific and Technical Information of China (English)

    Shun-Li Li; Xing-He Yu; Cheng-Peng Tan; Ronald Steel

    2014-01-01

    Junggar Basin, located in northern Xinjiang, presents continuous and multi-kilometer-thick strata of the Jurassic deposits. The Jurassic was entirely terrestrial lfuvial and lacustrine deltaic sedimentation. Eight outcrop sections across the Jurassic strata were meas-ured at a resolution of meters in southern Junggar Basin. Controlling factors of sedimentary evolution and palaeoclimate changes in Junggar Basin during the Jurassic were discussed based on lithology, fossils and tectonic setting. In the Early to Middle Jurassic, the warm and wide Tethys Sea generated a strong monsoonal circulation over the central Asian continent, and provided adequate moisture for Junggar Basin. Coal-bearing strata of the Badaowan, Sangonghe, and Xishanyao Formations were developed under warm and humid palaeocli-mate in Junggar Basin. In the late Middle Jurassic, Junggar Basin was in a semi-humid and semi-arid environment due to global warming event. Stratigraphy in the upper part of the Mid-dle Jurassic with less plant fossils became multicolor or reddish from dark color sediments. During the Late Jurassic, collision of Lhasa and Qiangtang Block obstructed monsoon from the Tethys Sea. A major change in climate from semi-humid and semi-arid to arid conditions took place, and reddish strata of the Upper Jurassic were developed across Junggar Basin.

  8. Jurassic sedimentary evolution of southern Junggar Basin:Implication for palaeoclimate changes in northern Xinjiang Uygur Autonomous Region,China

    Institute of Scientific and Technical Information of China (English)

    Shun-Li; Li; Xing-He; Yu; Cheng-Peng; Tan; Ronald; Steel

    2014-01-01

    Junggar Basin,located in northern Xinjiang,presents continuous and multikilometer-thick strata of the Jurassic deposits.The Jurassic was entirely terrestrial fluvial and lacustrine deltaic sedimentation.Eight outcrop sections across the Jurassic strata were measured at a resolution of meters in southern Junggar Basin.Controlling factors of sedimentary evolution and palaeoclimate changes in Junggar Basin during the Jurassic were discussed based on lithology,fossils and tectonic setting.In the Early to Middle Jurassic,the warm and wide Tethys Sea generated a strong monsoonal circulation over the central Asian continent,and provided adequate moisture for Junggar Basin.Coal-bearing strata of the Badaowan,Sangonghe,and Xishanyao Formations were developed under warm and humid palaeoclimate in Junggar Basin.In the late Middle Jurassic,Junggar Basin was in a semi-humid and semi-arid environment due to global warming event.Stratigraphy in the upper part of the Middle Jurassic with less plant fossils became multicolor or reddish from dark color sediments.During the Late Jurassic,collision of Lhasa and Qiangtang Block obstructed monsoon from the Tethys Sea.A major change in climate from semi-humid and semi-arid to arid conditions took place,and reddish strata of the Upper Jurassic were developed across Junggar Basin.

  9. JURASSIC PALEONTOLOGICAL HERITAGE OF MURCIA (BETIC CORDILLERA, SOUTH-EASTERN SPAIN

    Directory of Open Access Journals (Sweden)

    GREGORIO ROMERO

    2004-03-01

    Full Text Available Jurassic rocks of the External and Internal Zones of the Betic Cordillera are widespread in the province of Murcia. Four areas are considered of special interest for stratigraphical and paleontological analysis: a Sierra Quípar and b Sierras Lúgar-Corque (External Subbetic, c Sierra Ricote (Median Subbetic and d Sierra Espuña (Malaguide Complex. The first two contain Jurassic sections including Sinemurian-Tithonian deposits, and major stratigraphic discontinuities, containing significant cephalopod concentrations of taphonomic and taxonomic interest, occuring in the Lower-Upper Pliensbachian, Lower/Middle Jurassic and Middle/Upper Jurassic boundaries. These areas are also relevant for biostratigraphical analysis of the Middle-Upper Jurassic interval. In the Sierra de Ricote, the Mahoma section is of especial interest for the study of Lías/Dogger transition. Casa Chimeneas section constitutes the best Subbetic site for the analysis of the Lower/Upper Bajocian boundary. In the La Bermeja-Casas de Vite area, the Bajocian-Tithonian interval is well-represented, including a parastratotype of the Radiolarite Jarropa Formation. Finally, the Malvariche section in Sierra Espuña represents the best Jurassic succession of Internal Zones of the Betic Cordillera and could be considered as a reference section for this Betic Domain. In this paper a heritage evaluation has been carried out for these classical jurassic sections with the object of protecting these sites according to the legal framework prevailing in the province of Murcia.

  10. 柴北缘鱼卡大煤沟组七段油页岩开发价值*%Developmental Value of Oil Shale in the 7th Member of Middle Jurassic in Yuqia Area,Qaidam Basin

    Institute of Scientific and Technical Information of China (English)

    马新民; 郝海燕; 马峰; 段国禄; 程玉红

    2013-01-01

      Aimed at the 7th member of Middle Jurassic(J2d7)in Yuqia area,we undergo the solid mineral development and the comprehensive utilizationstudy. Accordingly,this study firstly discussed the tectonic background and sedimentary environment of the oil shale formed in Yuqia area based on the data from the field outcrop measured section,drilling,seismic data,sample analysis,and so on. Then economic and technological evaluations for the oil shale deposit were made according to seismic data and sample analysis. Assessment results show that the oil shale in Yuqia area is characteristic of high quality,shallow burying and big reserve. Thus it has a great potential value for development. Finally,taking into consideration developmental experiences in the world and the actual condition of Qaidam Basin,for the first time the strategy for mining and utilization of oil shale deposit in Yuqia area is proposed in this paper.%  针对柴达木盆地鱼卡地区中侏罗统大煤沟组七段(J 2 d 7)油页岩,开展了以固体矿产形式的开发、综合利用的研究。通过野外实测剖面、钻井、地震资料、样品分析,对鱼卡凹陷油页岩形成的构造背景、沉积环境进行了探讨,并对鱼卡油页岩矿产进行资源经济技术评价,认为鱼卡地区油页岩品质好,储量大,具有很好的开发价值。对其进行勘探、开发,一方面可以改善柴达木盆地当前能源短缺的局面,另一方面通过循环利用,有利于促进柴达木地区的农牧业生产。借鉴中外多年来油页岩开发经验,结合柴达木地区的实际情况,提出了地上开采和原位开采相结合,以提取页岩油、燃烧发电、燃烧取暖为主,建筑材料、有机复合肥等循环经济为辅的开发方案。

  11. Jurassic Tectonics of North China: A Synthetic View

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yueqiao; DONG Shuwen; ZHAO Yue; ZHANG Tian

    2008-01-01

    This paper gives a synthetic view on the Jurassic tectonics of North China, with an attempt to propose a framework for the stepwise tectonic evolution history. Jurassic sedimentation, deformation and magmatism in North China have been divided into three stages. The earliest Jurassic is marked by a period of magmatism quiescence (in 205-190 Ma) and regional uplift, which are considered to be the continuation of the "Indosinian movement" characterized by continent-continent collision between the North and South China blocks. The Early to Middle Jurassic (in 190-170 Ma) was predominated by weak lithospheric extension expressed by mantle-derived plutonism and volcanism along the Yanshan belt and alongside the Tan-Lu fault zone, normal faulting and graben formation along the Yinshan-Yanshan tectonic belt, depression and resuming of coal-bearing sedimentation in vast regions of the North China block (NCB). The Middle to Late Jurassic stage started at 165,.5 Ma and ended up before 136 Ma; it was dominated by intensive intraplate deformation resulting from multi-directional compressions. Two major deformation events have been identified. One is marked by stratigraphic unconformity beneath the thick Upper Jurassic molasic series in the foreland zones of the western Ordos thrust-fold belt and along the Yinshan-Yanshan belt; it was predated 160 Ma. The other one is indicated by stratigraphic unconformity at the base of the Lower Cretaceous and predated 135 Ma. During this last stage, two latitudinal tectonic belts, the Yinshan-Yanshan belt in the north and the Qinling-Dabie belt in the south, and the western margin of the Ordos basin were all activated by thrusting; the NCB itself was deformed by the NE to NNE-trending structural system involving thrusting, associated folding and sinistral strike-slip faulting, which were spatially partitioned. Foliated S-type granitic plutons aged 160-150 Ma were massively emplaced in the Jiao-Liao massif east of the Tan-Lu fault zone and

  12. Jurassic domes in the North Sea - northern North Atlantic region

    Energy Technology Data Exchange (ETDEWEB)

    Surlyk, F. [Univ. of Copenhagen, Geological Inst., Copenhagen (Denmark)

    1996-12-31

    The stratigraphic and tectonic evolution of the Jurassic of East Greenland, the Norwegian Shelf and the North Sea is remarkably similar. A major Middle Jurassic unconformity occurs in all three areas. In the North Sea it is commonly termed the `Mid-Cimmerian Unconformity` and is characterized by progressive truncation of the underlying section towards a centre at the triple junction between the Central Graben, Viking Graben and Moray Firth. Strata above the unconformity show a progressive Late Aalenian-Early Kimmeridgian onlap in the same direction. These relations have been interpreted as caused by Early Jurassic uplift and of a major thermal dome in the central North Sea, followed by Medial and Late Jurassic rifting, erosion, deflation and transgression of the dome. The East Greenland unconformity shows progressive truncation of underlying strata from south to north, and Bajocian to Callovian onlap in the same direction. The same pattern seems to be developed on the conjugate Norwegian margin. This suggests the possibility that the three unconformities have similar causes for their development. It is proposed that major rift domes formed in the Central North Sea and in the Greenland-Norway seaway in Early Jurassic times. The domes were eroded and gradually deflated during Medial Jurassic times and were finally submerged by the Late Oxfordian-Kimmeridgian. They were associated with volcanism and rifting which was delayed with respect to dome initiation. Roughly contemperaneous domes were present west of Britain, north of the Porcupine Seabight, and in Scania, southern Sweden, as reflected by development of asymmetrical unconformities showing progressive truncation of underlying strata, onlap of overlying Jurassic strata, and associated intrusive and extrusive volcanism. The domes are related to impingement of the heads of transient mantle plumes at the base of the lithosphere. The associated unconformities are thus of non-eustatic nature. Domal uplift and

  13. Effects of hydroclimatic anomalies on bacteriological quality of the Middle Paraná River (Santa Fe, Argentina).

    Science.gov (United States)

    Emiliani, F

    2004-01-01

    Lenitic and lotic aquatic environments were studied in the Middle Paraná River basin, one of the largest rivers of the world (basin: 1,510,000 km2, length: 2,570 km). The Paraná River (S 31 degrees 42' 04"; W 60 degrees 29' 39"), during El Niño-Southern Oscillation (ENSO) (1997-1998), registered maximum flows of 29,962 m3 s(-1) (more than twice the mean flow) and also positive pluvial anomalies (A) (from +120 mm to +161 mm). However, concentrations of Escherichia coli remained low, with values similar to the mean (p > 0.05) (1.3802 log10cfu/100 ml). Only a maximum peak (1.903 log10cfu/100 ml), significantly higher than the mean (p < 0.0001), was detected during the ascending phase of the flood pulse. During La Niña (September 1999-March 2000; Q = 11,255 m3 s(-1); A = -78 mm to -84 mm), concentrations of E. coli were significantly lower than the mean (p < 0.0001). During the post-Niña period, with normal flows (Q = 14,900 m3 s(-1)) but with strong positive pluvial anomalies (A = +118 mm to +377 mm), the fecal indicator density reached maximum values (up to 2.699 log10cfu/100 ml, p < 0.0001). The multiple regression model used with all the results obtained in the Paraná River showed that variations in concentrations of E. coli are mainly explained by pluvial precipitations and hydrometric level (p = 0.001). Temporal patterns of concentrations of E. coli in a small, secondary course (Q = 101 m3 s(-1)) followed those of the Paraná River, but concentrations and peaks of E. coli produced by exceptional rains showed a higher magnitude (maximum: 3.325 log10cfu/100 ml). In the floodplain lakes, away from urban centers, concentrations of E. coli were not associated to hydroclimatic anomalies, but directly to vegetable cover: maximum concentrations were always registered during periods that lakes remained covered by floating macrophytes (mainly Eichhornia crassipes); on the contrary, minimum concentrations were registered during periods without vegetable cover.

  14. Dinosaur tracks from Middle-Upper Jurassic Santai Formation:New materials and new interpretation%山东蒙阴盆地中晚侏罗世三台组恐龙足迹化石新材料新认识

    Institute of Scientific and Technical Information of China (English)

    李日辉; 刘明渭; 杜圣贤

    2015-01-01

    对山东蒙阴盆地三台组以前及新发现的三趾型恐龙足迹化石开展了综合研究,认为应归入翘脚龙足迹属Grallator,其造迹者是小型兽脚类恐龙而非此前认为的鸟脚类恐龙,是目前山东省时代最老的恐龙足迹化石,也是中晚侏罗世恐龙活动的唯一证据。%New revealed and previously reported dinosaur tracks,which are all from Middle-Upper Juras-sic Santai Formation of the Mengyin basin in Yangzhuang,Xintai City,Shandong Province,are syntheti-cally studied herein.These tracks are all tridactyl,longer than wide (ranges 12.0~17.5 cm in length and 9.5~12.4 cm in width),and the track length/width ratios range between 1.3 and 1.4.One of the track (LR-XT10.1)even shows clear sharp claw traces.All these features demonstrate that these traces are of theropod,instead of ornithopod as previously interpreted,dinosaur affinity,and they are herein tentatively labeled as Grallator isp.The tracks from the Santai Formation are the earliest dinosaur record ever repor-ted in Shandong Province,it also indicate that small-scale theropod dinosaurs once existed in the Megnyin basin during Middle-Late Jurassic time.

  15. The jurassic events in the Greater Caucasus basin (Northern Neotethys and the Neuquén basin (West Gondwana: a comparison

    Directory of Open Access Journals (Sweden)

    Dmitry A. Ruban

    2008-12-01

    Full Text Available Quite a few common tectonic, palaeoenvironmental, and palaeobiological events have been recognized in the Jurassic evolution of the Greater Caucasus basin (Northern Neotethys and the Neuquén basin (West Gondwana. Both basins were originated by the same planetary-scale tectonic force, i.e., by the activity of the Intrapangaean Shear Zone stretching eastwards along the Eurasian margin as the Northern Tethyan Shear Zone. An oxygen depletion occurred in both studied regions in the Toarcian as a result of global anoxia, which provoked a mass extinction. In both basins, the Callovian was a time for the carbonate platform growth, although in the Greater Caucasus, a carbonate platform appeared only in the Late Callovian. A salinity crisis occurred in the Greater Caucasus during the Kimmeridgian-Tithonian, whereas the same took place twice in the Neuquén basin - in the Middle Callovian and in the late Oxfordian-Kimmeridgian. These events were related to the global epoch of evaporite deposition. Some important differences between the considered basins are also documented. Palaeontological data from the Neuquén basin suggest against the mass extinction at the Jurassic-Cretaceous transition. In contrast, data from the Greater Caucasus basin permit to recognize this global event, although its regional peak occurred in the Berriasian. The Jurassic transgressions and regressions in the Greater Caucasus and western Argentina differed, facts that may be explained by the differences in the regional geodynamics. The only common pattern was a stepwise transgression during the Sinemurian-Pliensbachian.

  16. 鄂尔多斯盆地吴起地区侏罗纪早中期河流沉积及油气分布%Study on fluvial deposits and oil & gas distribution of early and middle Jurassic in Wuqi area,Ordos Basin

    Institute of Scientific and Technical Information of China (English)

    孟立娜; 李凤杰; 方朝刚; 李磊; 林洪

    2012-01-01

    应用现代沉积学理论,结合岩心观察描述、钻井、测井等资料,对鄂尔多斯盆地吴起地区侏罗纪早中期富县组到延安组延10、9、8期的沉积体系、岩相古地理特征及演化进行了详细研究,认为早侏罗世富县组和中侏罗世延安组延10期为深切河谷充填的辫状河沉积,延9和延8期则发育曲流河沉积.这2种河流沉积经历了有规律的继承性演化:富县组河谷充填作用最强,辫状河道砂体沉积厚度最大.延10期河谷进一步填平补齐,河谷斜坡上次级河道溯源增长、侧向侵蚀使河道变宽,漫滩分布面积减小.延9和延8期,古地形差异进一步减弱,河流转型为曲流河,河道和漫滩沉积均发育.吴起地区侏罗纪早中期河流发育辫状河和曲流河2种河流沉积模式.沉积相对富县组-延安组延8油层组油藏分布起主要控制作用,油气聚集主要受河道砂体展布控制,储层发育的河道砂体是该区今后勘探的主要目标.%On the basis of core observation,well drilling datalogging data and so on,the characteristics and evolution of the sedimentary system from Fuxian Formation to Yan10, Yan 9, Yan 8 reservoirs of Yan an Formation of early and middle Jurassic in Wuqi are-a, Ordos Basin are studied in detail using modem sedimentology theory. It is held that Fuxian Formation of early Jurassic and YanlO reservoir of middle Jurassic are dominated by deep valley filling braided fluvial deposits, and Yan 9 and Yan 8 reservoirs are dominated by meandering fluvial deposits. The two types of fluvial deposits experienced regular inherited evolution. The braided sand-body of Fuxian Formation is the thickest because of the strongest valley packing action. During YanlO period,the filling process continued,headward e-rosion was developed on the sub-valley slopes, the channel grew wider due to lateral erosion and the distribution range of flood plain reduced. During Yan 9 and Yan 8 periods, river became

  17. Jurassic Progonocimicidae (Hemiptera) from China and phylogenetic evolution of Coleorrhyncha

    Institute of Scientific and Technical Information of China (English)

    SZWEDO; Jacek

    2009-01-01

    The fossil record of Progonocimicidae of Hemiptera suborder Coleorrhyncha from China is reviewed. Ovicimex laiyangensis Hong et Wang, 1990, from the Lower Cretaceous of Laiyang, is excluded from Coleorrhyncha. The available generic name Mesocimex Hong, 1983 is resurrected from synonymy and proposed for replacement of the preoccupied name and junior homonym Mesoscytina Hong, 1983, non Mesoscytina Tillyard, 1919. It resulted in following new combinations: Mesocimex abditus (Yu. Popov, 1982) comb. n., Mesocimex ambiguus (Yu. Popov, 1985) comb. n., Mesocimex brunneus (Hong, 1983), comb. n., Mesocimex fidus (Yu. Popov, 1982) comb. n., Mesocimex intermedius (Yu. Popov, 1985) comb. n., Mesocimex kuzbasicus (Yu. Popov, 1985) comb. n., Mesocimex liliputus (Yu. Popov, 1988) comb. n., Mesocimex minutus (Yu. Popov, 1982) comb. n., Mesocimex modestus (Yu. Popov, 1985) comb. n., Mesocimex paulinus (Yu. Popov, 1982) comb. n., Mesocimex cognatus (Yu. Popov, 1982) comb. n. An annotated list of species of Mesocimex is given. In addition, a new species, Mesocimex lini sp. nov., is described based on well-preserved specimens with wings and bodies from the Middle Jurassic of Daohugou, China. This discovery supports the Middle Jurassic age of Daohugou Lagerstatte, since all species of Mesocimex are confined to the Lower-Middle Jurassic. The phylogenetic evolution of Coleorrhyncha is discussed: Cicadocorinae, Karabasiinae, Hoploridiinae, and Peloridiidae are monophyletic clades whereas Progonocimicinae and Karabasidae are clearly paraphyletic groups.

  18. Occurrence of sauropod dinosaur tracks in the Upper Jurassic of Chile (redescription of Iguanodonichnus frenki)

    Science.gov (United States)

    Moreno, Karen; Benton, Michael J.

    2005-12-01

    New observations from the only studied Upper Jurassic dinosaur unit in South America, the Baños del Flaco Formation, Chile, are presented herein. The original description of the ichnospecies Iguanodonichnus frenki contains several mistakes and information that needs updating. Therefore, we provide a redescription, including new data collected in the field, that supports I. frenki as a sauropod in origin on the basis of the following features: step angles average less than 110°; pes prints intersect the trackway midline; pes prints are longer than wide, with the long axis rotated outward; the claw impression of digit I is prominent and directed forward; and claws on digits II, III, and IV are strongly reduced. These morphological characteristics might give clues about the pes morphology of the South American Jurassic sauropods, whose foot bone remains are scarce. The presence of this sauropod ichnospecies in the Late Jurassic agrees with Early-Middle Jurassic faunal associations in South America.

  19. JURASSIC PALEOGEOGRAPHY OF THE PIENINY AND OUTER CARPATHIAN BASINS

    Directory of Open Access Journals (Sweden)

    JAN GOLONKA

    2004-03-01

    Full Text Available The Jurassic history of the Pieniny/Outer Carpathian basins reflects the evolution of the Circum-Tethyan area, especially its Alpine Tethys part. The Alpine Tethys that is Ligurian, Penninic Oceans and Pieniny/Magura Basin constitute the extension of the Central Atlantic system. The synrift stage lasted in the Pieniny/Magura Basin from late Early Jurassic to Tithonian (the Magura Unit constitutes the southernmost part of the Outer Flysch Carpathians. The Pieniny rift opened during Pliensbachian – Aalenian. The central Atlantic and Alpine Tethys went into a drifting stage during the Middle Jurassic. The Late Jurassic (Oxfordian-Kimmeridgian history of the Pieniny/Magura Basin reflects strongest facial differentiation within sedimentary basin where mixed siliceous-carbonate sedimentation took place. Greatest deepening effect is indicated by widespread Oxfordian radiolarites, which occur in the all basinal successions, whereas the shallowest zone is completely devoid of siliceous intercalations at that time (sedimentation from Ammonitico Rosso facies up to coral reef limestone. The southern part of the North European Platform, north from the Pieniny/Magura realm, started to be rifted during Late Jurassic time and Silesian Basin in the Outer Western Carpathians and Sinaia Basin in the Eastern Carpathians, with black, mainly redeposited marls have been created. The outer sub-basins were differentiated during the latest (Hauterivian-Barremian phase of basinal development. The connection of Silesian Basin with Sinaia and Southern Carpathian Severin areas suggests the NW-SE direction of the basinal axis while the orientation of the Pieniny Klippen Belt/Magura Basin was SW-NE so, two Outer Carpathian perpendicular directions are possible within the basins. Major reorganization happened during the Tithonian-Berriasian time. It was reflected by both paleoceanographical and paleoclimatical changes. The Neo-Cimmerian tectonic events as well as main phase

  20. Archosaur evolution during the Jurassic: a southern perspective La evolución de los arcosaurios durante el Jurásico: una perspectiva desde el Sur.

    Directory of Open Access Journals (Sweden)

    Oliver W. M. Rauhut

    2008-12-01

    Full Text Available The fossil record of archosaurs - crocodylomorphs, pterosaurs and dinosaurs - from the Jurassic of the Southern Hemisphere is critically reviewed, and its evolutionary implications are evaluated. Although several important faunas and also isolated finds are known from Gondwana, the record in total is still very patchy, and any evolutionary scenario based on this record should be seen as tentative. Compared to the Northern Hemisphere, southern archosaurs are much more poorly known, which is especially true for terrestrial crocodiles and pterosaurs. Marine crocodiles are rather well represented in south-western South America, whereas the report of terrestrial archosaurs is currently best for Africa. However, in South America, important and especially promising archosaur faunas are known from the Callovian Cañadón Asfalto and the (?Tithonian Cañadón Calcáreo formations of Chubut province, Argentina. Early and Middle Jurassic Gondwanan archosaurs demonstrate that the faunas of that period still had a generally Pangean distribution, whereas first indications of differential archosaur evolution in the Northern and Southern Hemispheres are evident in Late Jurassic Gondwanan faunas.El presente trabajo incluye una revisión crítica del registro fósil de los arcosaurios - cocodrilos, pterosaurios y dinosaurios - del Jurásico del Hemisferio Sur. Se evalúan además, sus implicancias evolutivas. Aunque se conocen varias faunas importantes y hallazgos aislados, el registro, en su totalidad, es todavía incompleto y cualquier escenario evolutivo basado en este registro debería verse como tentativo. En comparación con la situación en el Hemisferio Norte, es mucho menos lo que sabemos sobre los arcosaurios del Hemisferio Sur, y esto es especialmente cierto para los cocodrilos terrestres y pterosaurios. Los cocodrilos marinos están bastante bien representados en el sudoeste de Sudamérica, en tanto que el registro de arcosaruios terrestres es

  1. 柴达木盆地德令哈拗陷中侏罗统烃源岩有机地球化学特征%Organic geochemical characteristics of Middle Jurassic hydrocarbon source rocks in Delingha depression of Qaidam Basin

    Institute of Scientific and Technical Information of China (English)

    陈迎宾; 张寿庭

    2011-01-01

    Middle Jurassic is the main layer system of hydrocarbon source rocks which develops widely in the Delingha depression. Field geological survey and organic geochemical analysis indicate that Middle Jurassic source rocks mainly include oil shale, mudstone, carbonaceous mudstone and coal.The oil shale is a good hydrocarbon-generating rock. Whose mass fraction of organic carbon averages 7.95% and the type of organic matter is I and Ⅱ. Mudstone has different organic matter abundances,but over 80% samples whose mass fraction of organic carbon is more than 1% and over 65% samples whose mass fraction of organic carbon is more than 1.5 %. The type of organic matter of mudstone is Ⅱ and Ⅲ 1, and the mudstone is evaluated as poor to moderate source rocks. Carbonaceous mudstone whose mass fraction of organic carbon averages 10. 89 % and the type of organic matter is Ⅲ 1 and Ⅲ 2,so it belongs to poor hydrocarbon source rocks. The coal is the worst, and it belongs to a nonhydrocarbon source rock or poor hydrocarbon source rock. Most of the organic matter in the outcrop source rocks belongs to unbaked to low maturity, and a little of the organic matter belongs to maturity. It can be deduced that most of the organic matter in a peak period of oil generation and expulsion has a high maturity in the depression. The composition and the distribution of hydrocarbon compounds indicate that Middle Jurassic belongs to a fresh water deposit environment, and there develops semi-deep lake facies and deep lake facies which are good depositional settings to deploy source rocks in the Delingha depression.%柴达木盆地德令哈拗陷中侏罗统广泛发育,是该区主要的烃源岩层系.野外地质调查及有机地球化学分析表明,中侏罗统烃源岩主要以油页岩、泥岩、碳质泥岩和煤为主.油页岩有机碳的质量分数平均为7.95%,有机质类型属Ⅰ-Ⅱ型,为好生油岩;泥岩的有机质丰度交化大,但80%以上的样品

  2. A mysterious giant ichthyosaur from the lowermost Jurassic of Wales

    Directory of Open Access Journals (Sweden)

    Jeremy E. Martin

    2015-12-01

    Full Text Available Ichthyosaurs rapidly diversified and colonised a wide range of ecological niches during the Early and Middle Triassic period, but experienced a major decline in diversity near the end of the Triassic. Timing and causes of this demise and the subsequent rapid radiation of the diverse, but less disparate, parvipelvian ichthyosaurs are still unknown, notably because of inadequate sampling in strata of latest Triassic age. Here, we describe an exceptionally large radius from Lower Jurassic deposits at Penarth near Cardiff, south Wales (UK the morphology of which places it within the giant Triassic shastasaurids. A tentative total body size estimate, based on a regression analysis of various complete ichthyosaur skeletons, yields a value of 12–15 m. The specimen is substantially younger than any previously reported last known occurrences of shastasaurids and implies a Lazarus range in the lowermost Jurassic for this ichthyosaur morphotype.

  3. Advances in the study of vertebrate fossils of the Middle Jurassic Yanliao biota in western Liaoning Province and adjacent areas%辽宁西部及邻区中侏罗世燕辽生物群脊椎动物化石研究进展

    Institute of Scientific and Technical Information of China (English)

    郭相奇; 韩建刚; 姬书安

    2012-01-01

    近年来,在中国辽宁西部、内蒙古东南部、河北北部中侏罗世髫髻山组和九龙山组中发现了丰富的脊椎动物、无脊椎动物和植物化石,这一化石群被称为燕辽生物群.燕辽生物群已正式命名的脊椎动物26属28种,包括鱼类1属1种、两栖类4属4种、有鳞类1属1种、翼龙类10属12种、兽脚类恐龙5属5种、哺乳类5属5种.燕辽生物群的脊椎动物化石对研究长羽毛兽脚类恐龙的演化、翼龙类的分类演化、滑体两栖类的分异等具有重要意义.虽然辽宁西部及邻区燕辽生物群脊椎动物的多样性不及同一地区早白垩世的热河生物群,但它为认识这一地区晚中生代生物群的演替提供了极为重要的依据.%In recent years, numerous fossil vertebrates, invertebrates and plants have been found in the Middle Jurassic Tiaojishan and Jiulongshan Formations in western Liaoning, southeastern Inner Mongolia and northern Hebei. This biota is called Yanliao biota. Up till now, 28 species of different vertebrate groups have been formally named, which include 1 fish, 4 amphibians, 1 lizard, 12 pterosaurs, 5 theropods, and 5 mammals. The vertebrates of this biota have great significance for studying the theropod evolution, the pterosaur classification, and the lissamphibian diversity. Although the diversity of the Middle Jurassic Yanliao biota is less than that of the Early Cretaceous Jehol biota, it provides important evidence for understanding the succession of the Late Mesozoic biotas in this region.

  4. Jurassic extension and Cenozoic inversion tectonics in the Asturian Basin, NW Iberian Peninsula: 3D structural model and kinematic evolution

    Science.gov (United States)

    Uzkeda, Hodei; Bulnes, Mayte; Poblet, Josep; García-Ramos, José Carlos; Piñuela, Laura

    2016-09-01

    We constructed a geological map, a 3D model and cross-sections, carried out a structural analysis, determined the stress fields and tectonic transport vectors, restored a cross section and performed a subsidence analysis to unravel the kinematic evolution of the NE emerged portion of the Asturian Basin (NW Iberian Peninsula), where Jurassic rocks crop out. The major folds run NW-SE, normal faults exhibit three dominant orientations: NW-SE, NE-SW and E-W, and thrusts display E-W strikes. After Upper Triassic-Lower Jurassic thermal subsidence, Middle Jurassic doming occurred, accompanied by normal faulting, high heat flow and basin uplift, followed by Upper Jurassic high-rate basin subsidence. Another extensional event, possibly during Late Jurassic-Early Cretaceous, caused an increment in the normal faults displacement. A contractional event, probably of Cenozoic age, led to selective and irregularly distributed buttressing and fault reactivation as reverse or strike-slip faults, and folding and/or offset of some previous faults by new generation folds and thrusts. The Middle Jurassic event could be a precursor of the Bay of Biscay and North Atlantic opening that occurred from Late Jurassic to Early Cretaceous, whereas the Cenozoic event would be responsible for the Pyrenean and Cantabrian ranges and the partial closure of the Bay of Biscay.

  5. Response to Comment on "A Jurassic ornithischian dinosaur from Siberia with both feathers and scales".

    Science.gov (United States)

    Godefroit, Pascal; Sinitsa, Sofia M; Dhouailly, Danielle; Bolotsky, Yuri L; Sizov, Alexander V; McNamara, Maria E; Benton, Michael J; Spagna, Paul

    2014-10-24

    Lingham-Soliar questions our interpretation of integumentary structures in the Middle-Late Jurassic ornithischian dinosaur Kulindadromeus as feather-like appendages and alternatively proposes that the compound structures observed around the humerus and femur of Kulindadromeus are support fibers associated with badly degraded scales. We consider this hypothesis highly unlikely because of the taphonomy and morphology of the preserved structures.

  6. Reconstruction of Original SedimentaryProvince of the Jurassic in the Northwestern China%西北地区侏罗纪原始沉积区恢复

    Institute of Scientific and Technical Information of China (English)

    薛良清; 李文厚

    2000-01-01

    The Jurassic strata are widely distributed in the northwesternChina. The Early to early Middle Jurassic strata are major coal-bearing strata in the northwestern China that consist of sedimentary products of warm-humid climte,which are easily traced and correlated regionally. The late Middle to Late Jurassic strata are mainly composed of red beds, interbedded conglomerate and light-gray sandstones deposited in the alluvial and fluvial environments, showing paleoclimate changed from humid to dry features. In recent years, hydrocarbon exploration and researches in the Jurassic of NW China found the following facts:many present basin-margin areas often lack basinmarginal coarse-grain sediments of the Jurassic, while present tectonic uplift belts separating sedimentary basins are not present in some periods of the Jurassic or even whole Jurassic. Thus, it is necessary to reconstruct original sedimentary province of the Jurassic basins in NW China. Reconstruction of sedimentary province of the Jurassic in NW China is based on marginal sedimentary facies analysis, stratigraphic contact relationship analysis, paleocurrent system analysis, and tectonic/structural framework analysis. Marginal sedimentary facies analysis focuses on identifying alluvial fan and fluvial depositional systems that define sedimentary extent of basins. Stratigraphic contact relationship analysis is study on relationship between the residual Jurassic strata and underlying or overlaying strata because the relationship reflects depositional setting of the Jurassic strata and transform extent after the Jurassic deposition. Paleocurrent system analysis can help recognize relationship among remade basins at present. Identification of source area, shape and boundary of basins can be carried out on the basis of paleocurrent distribution. Tectonic/structural framework directly or indirectly affects deposition, sometimes are main factor to control sdimentary province and distribution of depositional systems

  7. An arboreal docodont from the Jurassic and mammaliaform ecological diversification

    Science.gov (United States)

    Meng, Qing-Jin; Ji, Qiang; Zhang, Yu-Guang; Liu, Di; Grossnickle, David M.; Luo, Zhe-Xi

    2015-02-01

    A new docodontan mammaliaform from the Middle Jurassic of China has skeletal features for climbing and dental characters indicative of an omnivorous diet that included plant sap. This fossil expands the range of known locomotor adaptations in docodontans to include climbing, in addition to digging and swimming. It further shows that some docodontans had a diet with a substantial herbivorous component, distinctive from the faunivorous diets previously reported in other members of this clade. This reveals a greater ecological diversity in an early mammaliaform clade at a more fundamental taxonomic level not only between major clades as previously thought.

  8. The Jurassic of Denmark and Greenland: key elements in the reconstruction of the North Atlantic Jurassic rift system

    Directory of Open Access Journals (Sweden)

    Surlyk, Finn

    2003-10-01

    Full Text Available The Jurassic succession of Denmark is largely confined to the subsurface with the exception of exposures on the island of Bornholm in the Baltic Sea. In East Greenland, in contrast, the Jurassic is extensively exposed. Comparison of basin evolution in the two regions, which now occur on two separate plates, thus relies on highly different datasets. It is possible nevertheless to construct an integrated picture allowing testing of hypotheses concerning basin evolution, regional uplift, onset and climax of rifting, relative versus eustatic sea-level changes and sequence stratigraphic subdivision and correlation. On a smaller scale, it is possible to compare the signatures of sequence stratigraphic surfaces as seen on well logs, in cores and at outcrop and of sequences recognised and defined on the basis of very different data types. Breakdown of the successions into tectonostratigraphic megasequences highlights the high degree of similarity in overall basin evolution and tectonic style. An important difference, however, lies in the timing. Major events such as late Early - Middle Jurassic uplift, followed by onset of rifting, basin reorganisation and rift climax were delayed in East Greenland relative to the Danish region. This has important implications both for regional reconstructions of the rift system and for the understanding and testing of classical sequence stratigraphic concepts involving eustatic versus tectonic controls of basin evolution and stratigraphy.

  9. Paleogeographic and tectonic implications of the first paleomagnetic results from the Middle Late Cambrian Mesón Group: NW Argentina

    Science.gov (United States)

    Spagnuolo, Cecilia M.; Rapalini, Augusto E.; Astini, Ricardo A.

    2008-02-01

    The first paleomagnetic data from autochthonous Cambrian rocks in NW Argentina is reported to constrain the apparent polar wander path (APWP) of Gondwana during the Early Paleozoic. The paleomagnetic pole (Lat 4.5°S; Long 359.0°E; dp = 5.5; dm = 8.8; n = 26) was obtained from the red to purple sandstones of the Campanario Formation. These rocks present a characteristic remanence carried by fine-grained hematite. The pole indicates that during the Late Cambrian, rocks now exposed in the Eastern Cordillera of NW Argentina were deposited at relatively low latitudes (≈26°S), consistent with intense chemical alteration during wet and warm climates, as indicated from petrography of apparent first-cycle quarzites of the Mesón Group. However, the pole position is anomalous with respect to the most accepted apparent polar wander paths for Gondwana, suggesting that the study area (22°50'S, 65°00'W) underwent clockwise rotation of 38° ± 8°, likely related to the Cenozoic central Andes rotation pattern characteristic of the region.

  10. The First Stegosaur (Dinosauria, Ornithischia) from the Upper Jurassic Shishugou Formation of Xinjiang, China

    Institute of Scientific and Technical Information of China (English)

    JIA Chengkai; Catherine A. FOSTER; XU Xing; James M. CLARK

    2007-01-01

    A new stegosaur species, Jiangjunosaurus junggarensis, gen. et sp. nov., is erected based on a specimen collected from the Upper Jurassic upper section of the Shishugou Formation in the Junggar Basin, Xinjiang, China. It represents the first stegosaur from the Jurassic of Xinjiang and increases the diversity of the dinosaur fauna in the Shishugou Formation. The new genus is characterized by symmetrical and proportionally wide tooth crowns, a sub-rectangular axial neural spine seen in lateral view, and large openings on the lateral surfaces of the cervical centra. A preliminary character analysis suggests that this new taxon is more derived than the Middle Jurassic stegosaur Huayangosaurus but more primitive than most other known stegosaur species.

  11. Rafaela, Argentina

    OpenAIRE

    2004-01-01

    Brinda información acerca de la provincia de Rafaela, Argentina. Da a conocer el planeamiento estratégico de Rafaela, los temas a resolver con el sector privado, así como las acciones para abordar la relación público-privada.

  12. Argentina; Argentine

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-04-01

    This economical study summarizes the energy situation of Argentina: energy institutions and policy, energy companies (oil, electricity, gas, coal), energy supplies (resources, power production, petroleum, natural gas), prices and tariffs, consumption, economical stakes and perspectives (investments, agreements, projects). Energy data for the 1971-1999 period are summarized in graphs and tables. (J.S.)

  13. Triassic-Jurassic pteridosperms of Australasia: speciation, diversity and decline

    Energy Technology Data Exchange (ETDEWEB)

    Pattemore, G. A.; Rigby, J. F.; Playford, G.

    2015-07-01

    Pteridosperms are preserved abundantly in the Gondwanan Triassic, with many species exhibiting consider- able morphological variation that has been attributed to a hybridization model of speciation. This is an improbable explanation given that hybridization is very rare in gymnosperms. Allopatric speciation resulting from geographic and climatic provincialism is a more likely explanation for the morphological diversity which is well represented in Anisian Norian (Middle and Upper Triassic) floras of Australasia and elsewhere in Gondwana. Most specimens are distributed among three families: Umkomasiaceae, Peltaspermaceae and Matatiellaceae. These families, together with other possibly pteridospermous genera, are reviewed herein. Diversity in these families apparently declined by the Rhaetian and they did not persist into the Gondwanan post-Triassic. Australasian post-Triassic strata contain remarkably different floral assemblages to those of the Triassic. No fructifications are clearly pteridospermous and no remains show any obvious relationship with pteridosperms of the Gondwanan Triassic. Caytonialean fructifications are not known in Australasian strata; however, associated foliage has been reported from the Eastern Gondwanan Upper Triassic through Middle Jurassic including Australia. Much fern-like foliage, claimed to be pteridospermous from the Lower Jurassic through Eocene of Eastern Gondwana, lacks supporting evidence of such affiliation. (Author)

  14. Episodic Jurassic to Lower Cretaceous intraplate compression in Central Patagonia during Gondwana breakup

    Science.gov (United States)

    Navarrete, César; Gianni, Guido; Echaurren, Andrés; Kingler, Federico Lince; Folguera, Andrés

    2016-12-01

    From Lower Jurassic to Lower Cretaceous, several intraplate compression events affected discrete sectors of Central Patagonia, under a general context of crustal extension associated with Gondwana breakup. This was demonstrated by means of 2D and 3D seismic and borehole data, which show partial inversion of Lower and Middle Jurassic extensional structures of the Chubut and Cañadón Asfalto basins, during the earliest stages of breakup. A comparison with surrounding areas in Patagonia, where similar Jurassic intraplate compression was described, allowed the discrimination of three discrete pulses of subtle compression (C1: ∼188-185 Ma; C2: ∼170-163; C3: ∼157-136? Ma). Interestingly, episodic intraplate compressional events are closely followed by high flux magmatic events linked to the westward expansion of the Karoo-Ferrar thermal anomaly, which impacted on the lithosphere of southwest Gondwana in Lower Jurassic. In addition, we determined the approximate direction of the main compressive strain (σ1) compatible with other Jurassic intraplate belts of South America. These observations led us to propose a linkage between a thermo mechanically weakened continental crust due to LIPs activity, changes in plate motions and ridge-push forces generated by the opening of the Weddell Sea, in order to explain intraplate shortening, interrupted while Karoo LIPs magmatic invigoration took place.

  15. Magnetic properties of the remagnetized Middle-Ordovician limestones of the Ponón Trehué Formation (San Rafael Block, central-western Argentina): Insights into the Permian widespread Sanrafaelic overprint

    Science.gov (United States)

    Fazzito, Sabrina Y.; Rapalini, Augusto E.

    2016-10-01

    The widespread Sanrafaelic remagnetization reset most of the early Cambrian to mid-Ordovician carbonate platform of the Argentine Precordillera and the calcareous units of the San Rafael Block. We conducted a detailed rock-magnetic study on the Middle-Ordovician limestones of the Ponón Trehué Formation at both limbs of a tight anticline exposed in the San Rafael Block (Mendoza province, central-western Argentina) that are carriers of a syntectonic magnetization of Permian age. We found that the magnetic overprint in the Ponón Trehué Formation is carried by both pyrrhotite and magnetite, with goethite and subordinate haematite likely related to weathering. Hysteresis parameters, frequency dependence of magnetic susceptibility, Cisowski and modified Lowrie-Fuller tests suggest the presence of ultrafine particles of chemical origin. Demagnetization of natural remanent magnetization and of three-axis isothermal remanence confirm pyrrhotite and magnetite as important contributors to the remanence. Both minerals carry the same magnetic syntectonic component suggesting a coeval or nearly coeval remanence acquisition and therefore mineral formation. This and the results of the magnetic fabric analyses indicate an authigenic origin of the magnetic minerals during folding associated with the Sanrafaelic tectonic phase (ca. 280 Ma). Although the chemically active (oxidizing?) fluids expelled from the orogen as it developed in the early Permian is a viable explanation for the Sanrafaelic remagnetization, the role of the nearly coeval magmatism in Precordillera and the San Rafael Block remains to be properly evaluated.

  16. Argentina: spotlight.

    Science.gov (United States)

    Patriquin, W

    1987-10-01

    In 1987 Argentina had a population of 31.5 million, with an annual rate of increase of 1.6%. The total fertility rate was 3.3, and the birth rate was 24/1000 population. Mortality stood at 8/1000 population, and the infant mortality rate was 35.3/1000 live births. Life expectancy at birth is 70 years. 84% of the population lives in Argentina's urban areas. Current government policies call for regional development to maintain and increase population in rural areas and control growth in urban centers. 90% of the population is of European descent, largely as a result of high rates of immigration during the 1880s-1930s from countries such as Spain and Italy. In 1985 the gross national product per capita was US$2130. Argentina is rich in resources and almost self-sufficient in terms of basic foodstuffs, power supply, and advanced communication networks. On the other hand, political conflicts and economic crises have hindered the realization of both human and natural resource potential. 80% of the value of export products is the amount due in interest on foreign debts.

  17. A bizarre Jurassic maniraptoran from China with elongate ribbon-like feathers.

    Science.gov (United States)

    Zhang, Fucheng; Zhou, Zhonghe; Xu, Xing; Wang, Xiaolin; Sullivan, Corwin

    2008-10-23

    Recent coelurosaurian discoveries have greatly enriched our knowledge of the transition from dinosaurs to birds, but all reported taxa close to this transition are from relatively well known coelurosaurian groups. Here we report a new basal avialan, Epidexipteryx hui gen. et sp. nov., from the Middle to Late Jurassic of Inner Mongolia, China. This new species is characterized by an unexpected combination of characters seen in several different theropod groups, particularly the Oviraptorosauria. Phylogenetic analysis shows it to be the sister taxon to Epidendrosaurus, forming a new clade at the base of Avialae. Epidexipteryx also possesses two pairs of elongate ribbon-like tail feathers, and its limbs lack contour feathers for flight. This finding shows that a member of the avialan lineage experimented with integumentary ornamentation as early as the Middle to Late Jurassic, and provides further evidence relating to this aspect of the transition from non-avian theropods to birds.

  18. Amphibious flies and paedomorphism in the Jurassic period.

    Science.gov (United States)

    Huang, Diying; Nel, André; Cai, Chenyang; Lin, Qibin; Engel, Michael S

    2013-03-01

    The species of the Strashilidae (strashilids) have been the most perplexing of fossil insects from the Jurassic period of Russia and China. They have been widely considered to be ectoparasites of pterosaurs or feathered dinosaurs, based on the putative presence of piercing and sucking mouthparts and hind tibio-basitarsal pincers purportedly used to fix onto the host's hairs or feathers. Both the supposed host and parasite occur in the Daohugou beds from the Middle Jurassic epoch of China (approximately 165 million years ago). Here we analyse the morphology of strashilids from the Daohugou beds, and reach markedly different conclusions; namely that strashilids are highly specialized flies (Diptera) bearing large membranous wings, with substantial sexual dimorphism of the hind legs and abdominal extensions. The idea that they belong to an extinct order is unsupported, and the lineage can be placed within the true flies. In terms of major morphological and inferred behavioural features, strashilids resemble the recent (extant) and relict members of the aquatic fly family Nymphomyiidae. Their ontogeny are distinguished by the persistence in adult males of larval abdominal respiratory gills, representing a unique case of paedomorphism among endopterygote insects. Adult strashilids were probably aquatic or amphibious, shedding their wings after emergence and mating in the water.

  19. Petrophysical Properties of the Middle Jurassic Carbonates in the PICOREF Sector (South Champagne, Paris Basin, France Propriétés pétrophysiques du Dogger carbonaté dans le Secteur PICOREF (Sud Champagne, bassin de Paris, France

    Directory of Open Access Journals (Sweden)

    Delmas J.

    2010-05-01

    Full Text Available This article, carried out as part of the PICOREF Project for the CO2 storage in the aquifers of the Paris Basin, presents an important petrophysical database from the numerous petroleum wells drilled in the PICOREF Sector (south-eastern part of the Paris Basin between 1953 and 2001. These core data concern the three saline carbonated aquifers of the Middle Jurassic: the Oolithe Blanche and the Comblanchien formations, Upper Bathonian age, and the Dalle Nacrée formation, Lower Callovian age, that would be used for the CO2 sequestration. Located at –1230 to –1750 m sub sea in the studied sector, these carbonate reservoirs which cumulative thickness is about 150 m, outcrop in the Burgundy region, at about 80 km south-eastern the Sector where they are exploited in several quarries. The analysis of the 6800 routine measurements (porosity and permeability gathered for this study allowed to improve the knowledge of the petrophysical properties. Special measurements (mercury injection tests allowed to characterize the porous medium. Cet article, réalisé dans le cadre du Projet PICOREF(1 pour le stockage de CO2 dans les aquifères du bassin parisien, présente une importante base de données pétrophysiques issues des nombreux puits pétroliers forés dans le Secteur PICOREF (sud-est du bassin parisien entre 1953 et 2001. Ces données concernent les trois aquifères salins du Dogger carbonaté susceptibles d’être utilisés pour séquestrer du CO2 : l’Oolithe Blanche et le Comblanchien, d’âge Bathonien supérieur, ainsi que la Dalle Nacrée d’âge Callovien inférieur. Recoupés à des altitudes de – 1230 à – 1750 m/mer dans le secteur étudié, ces réservoirs carbonatés, dont l’épaisseur cumulée est de 150 m environ, affleurent en Bourgogne, à 80 km au sud-est du « Secteur », où ils sont exploités dans plusieurs carrières. L’analyse des 6800 mesures classiques (porosité et perméabilité rassemblées ici a permis d

  20. en Argentina

    Directory of Open Access Journals (Sweden)

    Patricia Davolos

    2005-01-01

    Full Text Available Hacia finales de la década pasada comienza a cobrar dinamismo la protesta social en Argentina como respuesta a la crisis resultante de las políticas neoliberales que dominaron la escena nacional en los noventa. En ese contexto, grupos de trabajadores ocupan empresas en riesgo de cerrar sus puertas, organizándose para operarlas en forma autogestionaria. Aquí se estudian las características del mercado de trabajo, así como las tradiciones y los recursos que permitieron a los trabajadores llevar adelante este tipo de acciones, delineando distintas trayectorias que otorgaron inteligibilidad al fenómeno analizado.

  1. ENVIRONMENTS AND FAUNAL PATTERNS IN THE KACHCHH RIFT BASIN, WESTERN INDIA, DURING THE JURASSIC

    OpenAIRE

    FRANZ THEODOR FÜRSICH; Callomon, John H.; DHIRENDRA K. PANDEY; ANAND K. JAITLY

    2004-01-01

    Marine Jurassic sediments (Bajocian-Tithonian) of the Kachchh Basin were deposited in a ramp setting. Except during the Middle and Late Bathonian, when a carbonate regime became established, the fill of the basin consists predominantly of siliciclastics. The sediments represent environments that range from coastal plains (rivers and associated flood plains with caliche nodules), deltas, brackish water lagoons, nearshore sand and iron-oolite bars of the inner ramp, generally situated above fai...

  2. Tectonic Evolution of the Jurassic Pacific Plate

    Science.gov (United States)

    Nakanishi, M.; Ishihara, T.

    2015-12-01

    We present the tectonic evolution of the Jurassic Pacific plate based on magnetic anomly lineations and abyssal hills. The Pacific plate is the largest oceanic plate on Earth. It was born as a microplate aroud the Izanagi-Farallon-Phoenix triple junction about 192 Ma, Early Jurassic [Nakanishi et al., 1992]. The size of the Pacific plate at 190 Ma was nearly half that of the present Easter or Juan Fernandez microplates in the East Pacific Rise [Martinez et at, 1991; Larson et al., 1992]. The plate boundary surrounding the Pacific plate from Early Jurassic to Early Cretaceous involved the four triple junctions among Pacific, Izanagi, Farallon, and Phoenix plates. The major tectonic events as the formation of oceanic plateaus and microplates during the period occurred in the vicinity of the triple junctions [e.g., Nakanishi and Winterer, 1998; Nakanishi et al., 1999], implying that the study of the triple junctions is indispensable for understanding the tectonic evolution of the Pacific plate. Previous studies indicate instability of the configuration of the triple junctions from Late Jurassic to Early Cretaceous (155-125 Ma). On the other hand, the age of the birth of the Pacific plate was determined assuming that all triple junctions had kept their configurations for about 30 m.y. [Nakanishi et al., 1992] because of insufficient information of the tectonic history of the Pacific plate before Late Jurassic.Increase in the bathymetric and geomagnetic data over the past two decades enables us to reveal the tectonic evolution of the Pacific-Izanagi-Farallon triple junction before Late Jurassic. Our detailed identication of magnetic anomaly lineations exposes magnetic bights before anomaly M25. We found the curved abyssal hills originated near the triple junction, which trend is parallel to magnetic anomaly lineations. These results imply that the configuration of the Pacific-Izanagi-Farallon triple junction had been RRR before Late Jurassic.

  3. Basin geodynamics and sequence stratigraphy of Upper Triassic to Lower Jurassic deposits of Southern Tunisia

    Science.gov (United States)

    Carpentier, Cédric; Hadouth, Suhail; Bouaziz, Samir; Lathuilière, Bernard; Rubino, Jean-Loup

    2016-05-01

    Aims of this paper are to propose a geodynamic and sequential framework for the late Triassic and early Jurassic of and south Tunisia and to evidence the impact of local tectonics on the stratigraphic architecture. Facies of the Upper Triassic to Lower Jurassic of Southern Tunisia have been interpreted in terms of depositional environments. A sequential framework and correlation schemes are proposed for outcrops and subsurface transects. Nineteen middle frequency sequences inserted in three and a half low frequency transgression/regression cycles were evidenced. Despite some datation uncertainties and the unknown durations of Lower Jurassic cycles, middle frequency sequences appear to be controlled by eustasy. In contrast the tectonics acted as an important control on low frequency cycles. The Carnian flooding was certainly favored by the last stages of a rifting episode which started during the Permian. The regression accompanied by the formation of stacked angular unconformities and the deposition of lowstand deposits during the late Carnian and Norian occured during the uplift and tilting of the northern basin margins. The transpressional activity of the Jeffara fault system generated the uplift of the Tebaga of Medenine high from the late Carnian and led to the Rhaetian regional angular Sidi Stout Unconformity. Facies analysis and well-log correlations permitted to evidence that Rhaetian to Lower Jurassic Messaoudi dolomites correspond to brecciated dolomites present on the Sidi Stout unconformity in the North Dahar area. The Early-cimmerian compressional event is a possible origin for the global uplift of the northern African margin and Western Europe during the late Carnian and the Norian. During the Rhaetian and the early Jurassic a new episode of normal faulting occured during the third low frequency flooding. This tectonosedimentary evolution ranges within the general geodynamic framework of the north Gondwana margin controlled by the opening of both

  4. Three new Jurassic euharamiyidan species reinforce early divergence of mammals.

    Science.gov (United States)

    Bi, Shundong; Wang, Yuanqing; Guan, Jian; Sheng, Xia; Meng, Jin

    2014-10-30

    The phylogeny of Allotheria, including Multituberculata and Haramiyida, remains unsolved and has generated contentious views on the origin and earliest evolution of mammals. Here we report three new species of a new clade, Euharamiyida, based on six well-preserved fossils from the Jurassic period of China. These fossils reveal many craniodental and postcranial features of euharamiyidans and clarify several ambiguous structures that are currently the topic of debate. Our phylogenetic analyses recognize Euharamiyida as the sister group of Multituberculata, and place Allotheria within the Mammalia. The phylogeny suggests that allotherian mammals evolved from a Late Triassic (approximately 208 million years ago) Haramiyavia-like ancestor and diversified into euharamiyidans and multituberculates with a cosmopolitan distribution, implying homologous acquisition of many craniodental and postcranial features in the two groups. Our findings also favour a Late Triassic origin of mammals in Laurasia and two independent detachment events of the middle ear bones during mammalian evolution.

  5. Study of the Factors Affecting the Abundance of Organic Matter in Jurassic Carbonate Rocks in Qiangtang Basin, Tibet

    Institute of Scientific and Technical Information of China (English)

    文志刚; 胡明毅; 龚文平; 肖传桃

    2004-01-01

    Field and laboratory analyses of carbonate rock samples from the Qiangtang Basin,Tibet, indicate that carbonate source rocks are mainly developed in the Middle Jurassic Xiali Formation and Upper Jurassic Suowa Formation. Comprehensive studies showed that the Suowa Formation carbonate source rocks have a favorable hydrocarbon-generating potential. The abundance of organic matter in the carbonate rocks is controlled mainly by sedimentary environment and inorganic compounds in the rocks, which is higher in the restricted platform facies than in the open platform facies. Organic carbon contents decrease with increasing CaO contents in the source rocks.

  6. Patagonia Argentina

    Directory of Open Access Journals (Sweden)

    A.J. Acuña

    2008-01-01

    Full Text Available La zona central de la Patagonia, Argentina, se encuentra sometida a explotación petrolera y sus suelos se caracterizan por ser deficientes en nitrógeno. Esto causaría un efecto negativo en los procesos de atenuación natural que se desarrollan en los suelos contaminados con hidrocarburos. El objeto de este estudio fue determinar cual es el efecto de la deficiencia de nitrógeno sobre la biodegradación de los hidrocarburos en un suelo de la Patagonia, Argentina. Se trabajó con tres microcosmos a los que se les realizó tratamientos diferentes. En uno se monitoreo la atenuación natural del sistema, en otro la fertilización con nitrógeno (N, fósforo (P y potasio (K, y en el último la fertilización con P y K. Durante el seguimiento se determinaron mineralización y medición de hidrocarburos, y se realizaron recuentos bacterianos y determinación de nitrato, nitrito y amonio. Los resultados indican que es posible la biodegradación de hidrocarburos en el suelo deficiente de nitrógeno de la Patagonia estudiado en tiempos mas prolongados que en aquellos que se realiza una fertilización con nitrógeno. El nitrógeno necesario para el proceso sería obtenido por los microorganismos del suelo por fijación biológica.

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

    Science.gov (United States)

    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.

  8. Dinosaur dynamics in the Jurassic Era

    Science.gov (United States)

    Lee, Scott

    2010-04-01

    Dinosaurs were fascinating animals and elicit much excitement in the classroom. Analysis of fossilized dinosaur trackways permits one to estimate the locomotion speeds and accelerations of these extinct beasts. Such analysis allows one to apply Newton's laws of motion to examples from the Jurassic Era.

  9. New Early Jurassic Tetrapod Assemblages Constrain Triassic-Jurassic Tetrapod Extinction Event

    Science.gov (United States)

    Olsen, P. E.; Shubin, N. H.; Anders, M. H.

    1987-08-01

    The discovery of the first definitively correlated earliest Jurassic (200 million years before present) tetrapod assemblage (Fundy basin, Newark Supergroup, Nova Scotia) allows reevaluation of the duration of the Triassic-Jurassic tetrapod extinction event. Present are tritheledont and mammal-like reptiles, prosauropod, theropod, and ornithischian dinosaurs, protosuchian and sphenosuchian crocodylomorphs, sphenodontids, and hybodont, semionotid, and palaeonisciform fishes. All of the families are known from Late Triassic and Jurassic strata from elsewhere; however, pollen and spore, radiometric, and geochemical correlation indicate an early Hettangian age for these assemblages. Because all ``typical Triassic'' forms are absent from these assemblages, most Triassic-Jurassic tetrapod extinctions occurred before this time and without the introduction of new families. As was previously suggested by studies of marine invertebrates, this pattern is consistent with a global extinction event at the Triassic-Jurassic boundary. The Manicouagan impact structure of Quebec provides dates broadly compatible with the Triassic-Jurassic boundary and, following the impact theory of mass extinctions, may be implicated in the cause.

  10. Dinosaur evolution. A Jurassic ornithischian dinosaur from Siberia with both feathers and scales.

    Science.gov (United States)

    Godefroit, Pascal; Sinitsa, Sofia M; Dhouailly, Danielle; Bolotsky, Yuri L; Sizov, Alexander V; McNamara, Maria E; Benton, Michael J; Spagna, Paul

    2014-07-25

    Middle Jurassic to Early Cretaceous deposits from northeastern China have yielded varied theropod dinosaurs bearing feathers. Filamentous integumentary structures have also been described in ornithischian dinosaurs, but whether these filaments can be regarded as part of the evolutionary lineage toward feathers remains controversial. Here we describe a new basal neornithischian dinosaur from the Jurassic of Siberia with small scales around the distal hindlimb, larger imbricated scales around the tail, monofilaments around the head and the thorax, and more complex featherlike structures around the humerus, the femur, and the tibia. The discovery of these branched integumentary structures outside theropods suggests that featherlike structures coexisted with scales and were potentially widespread among the entire dinosaur clade; feathers may thus have been present in the earliest dinosaurs.

  11. Reduced plumage and flight ability of a new Jurassic paravian theropod from China.

    Science.gov (United States)

    Godefroit, Pascal; Demuynck, Helena; Dyke, Gareth; Hu, Dongyu; Escuillié, François; Claeys, Philippe

    2013-01-01

    Feathered theropods were diverse in the Early Cretaceous Jehol Group of western Liaoning Province, China. Recently, anatomically distinct feathered taxa have been discovered in the older Middle-Late Jurassic Tiaojishan Formation in the same region. Phylogenetic hypotheses including these specimens have challenged the pivotal position of Archaeopteryx in bird phylogeny. Here we report a basal troodontid from the Tiaojishan Formation that resembles Anchiornis, also from Jianchang County (regarded as sister-taxa). The feathers of Eosinopteryx are less extensive on the limbs and tail than Anchiornis and other deinonychosaurians. With reduced plumage and short uncurved pedal claws, Eosinopteryx would have been able to run unimpeded (with large foot remiges cursorial locomotion was likely problematic for Anchiornis). Eosinopteryx increases the known diversity of small-bodied dinosaurs in the Jurassic, shows that taxa with similar body plans could occupy different niches in the same ecosystem and suggests a more complex picture for the origin of flight.

  12. Tango in the Mid-Jurassic: 10,000-Yr Geomagnetic Field Reversals

    Science.gov (United States)

    Steiner, M.

    2001-12-01

    A continuous magnetostratigraphic signature of Layer 2A from Jurassic Quiet Zone (JQZ) oceanic crust now is known from two separate paleo-magnetic data sets. Measurement/demagnetization along the length of the entire core at 5-cm intervals generated ~100,000 data points, whereas a suite of 472 discrete samples also were taken from throughout the core. Both data sets display the same magnetization pattern, a series of repeated sinusoidal inclination changes downhole. Six inter-vals of maximum inclination (three positive, three negative) are obser-ved. Maximum inclination intervals of +/-40° are separated by regions of smoothly varying intermediate inclination values. Despite lack of azmuithal orientation of the core, downhole magnetic logging (Larson et al., in prep.) shows full ~360° directional change in the magnetization vector. Therefore, the maximum inclination regions represent polarity intervals of the geomagnetic field, and six polarity intervals in stacked sequence are contained in the upper 400 m thickness of Layer 2A at this site. The time duration spanned by these six reversals was estimated from recent seismic studies of young ocean crustal construction on the East Pacific Rise (EPR). Estimates of completion of construction of Layer 2A within 1-3 km from the rise crest and typical EPR half-spreading rates of 5-8 cm/yr suggest that the studied 400 m of ocean crust represents 37,000-60,000 years. The fast construction of EPR crust implies that the Middle Jurassic geomagnetic field was reversing at a phenomenal rate of 5000-10,000 years. These data establish that the `quiet' signature in the oldest portion of the lineated magnetic anomaly patterns in the ocean crust is due to exceedingly rapid reversals of the geomagnetic field, because succes-sive, superposed opposite-polarity magnetic signatures will essentially cancel one another out at the sea surface. The width of the 'quiet' magnetic signature in the western Pacific Ocean implies that the 5000

  13. TRANSITION FROM CARBONATE PLATFORM TO PELAGIC DEPOSITION (MID JURASSIC- LATE CRETACEOUS, VOURINOS MASSIF, NORTHERN GREECE

    Directory of Open Access Journals (Sweden)

    NICOLAOS CARRAS

    2004-03-01

    Full Text Available A Jurassic- Cretaceous carbonate succession crops out along the Zyghosti Rema, Kozani (Northern Greece. The substratum consists of the ophiolitic succession of the Vourinos Massif (Pelagonian Domain: serpentinites tectonically overlain by basalts, with thin lenses of radiolarian cherts of middle Bathonian age. The contact with the overlying Jurassic limestones is tectonic. Eight informal units have been distinguished within the Mesozoic limestones, from the base upwards. (A bioclastic, intraclastic and oolitic packstone (Callovian- Oxfordian. (B bioclastic packstone and coral boundstone (Oxfordian . (C bioclastic and oncoidal wackestone with Clypeina jurassica (Oxfordian- Upper Kimmeridgian. (D (Upper Kimmeridgian- Portlandian: oncoidal packstone and rudstone (facies D1; intraclastic and bioclastic grainstone and packstone (facies D2; neptunian dykes with intraclastic and bioclastic wackestone and packstone filling (facies D3; neptunian dykes with Fe-Mn rich laterite filling and with pink silty filling of early Late Cretaceous age. An unconformity surface, due to emersion and erosion of the platform during the latest Jurassic- Early Cretaceous, is overlain by (E intraclastic, bioclastic packstone and grainstone (Cenomanian. (F massive body of debrites with coral, echinoderm, algae and rudist large clasts (facies F1 (Cenomanian; turbiditic beds of bioclastic, intraclastic and lithoclastic rudstone and grainstone (facies F2. (G thin bedded bioclastic mudstone and wackestone with planktonic foraminifers and radiolarians, alternating with turbiditic beds of bioclastic, intraclastic packstone and rudstone and with conglomeratic levels and slumped beds of the previous turbidites (upper Santonian- lower Campanian. (H: bioclastic packstone with planktonic foraminifers (facies H1 (lower Campanian - ?Maastrichtian; amalgamated turbiditic beds of bioclastic wackestone and packstone with planktonic foraminifers (facies H2; turbiditic beds of bioclastic

  14. LATE JURASSIC SCLERACTINIAN CORALS FROM G(E)RZ(E),NORTHWESTERN XIZANG (TIBET)%西藏改则的晚侏罗世石珊瑚

    Institute of Scientific and Technical Information of China (English)

    廖卫华; 纪占胜; 武桂春

    2012-01-01

    文中描述产自西藏北部改则县境内班公湖-怒江地层区内的石珊瑚17属23种(包括1个新种和6个未定种),根据珊瑚动物群的分析与对比可以确定它们的地质时代应为晚侏罗世(Late Jurassic),最可能是晚牛津期至启莫里期(Late Oxfordian-Kimmeridgian),那时正值全球性温暖气候环境下,在全世界不少地方,尤其是在特提斯(Tethys)海域形成了一定规模的珊瑚礁(coral-reef).%Although Mesozoic marine strata are well developed in Xizang (Tibet) and they include a very rich scleractinian coral fauna their study has been limited for a long time by the well known rigours of exploration on the Qinghai-Tibetan Plateau. The coral-bearing beds discussed here are located in the Late Oxfordian to Kimmeridgian Tukari Formation at northern Oma village of Gerze county, northwestern Xizang. They belong to the Bangong Co-Nujiang Stratigraphic Zone, which borders the Qiangtang Stratigraphic Zone in the North and the Gangdise Stratigraphic Zone in the South. The Jurassic scleractinian corals described and illustrated here from Oma comprise 17 genera and 23 species, including one new species - Stylosmil-ia xizangensis sp. nov. and six which are specifically indeterminable. Amongst them: Heliocoenia aff. etalloni and H. bandukidzea have been found from the Upper Jurassic in Azerbajan and Baingoin in northern Tibet, China. Heltocoenia orbignyi has been reported from the Upper Jurassic of Poland, Romania and Ge'gyai, northwestern Tibet, China. Isastraea bernensis is widely distributed in Late Jurassic limestones of Switzerland, France, Romania and Tingri in southern Tibet, China. Whereas Axosmilia sessilis occurs in the Middle Jurassic of Cutch, India, the Upper Jurassic of Germany and also at Baingoin in northern Tibet, China. Cryptocoenia octosepta is widely distribu- ted occurring in Switzerland, Georgia and Baingoin, northern Tibet, China. The geological range of genus Dermosmilia is from Jurassic to

  15. Basin architecture, salt tectonics, and Upper Jurassic structural styles, DeSoto Canyon Salt basin, northeastern Gulf of Mexico

    Energy Technology Data Exchange (ETDEWEB)

    MacRae, G.; Watkins, J.S. (Texas A M Univ., College Station, TX (United States))

    1993-10-01

    Despite the Gulf of Mexico being a mature hydrocarbon province, the least understood aspects of the basin's geologic history are undoubtedly those concerning pre-Middle Jurassic tectonic events and their implication for the tectonic and sedimentary evolution of the region. Despite awareness of the importance of continental extension during rifting, there are few quantitative studies that show the influence of crustal extension on basin architecture, the distribution of salt, and Late Jurassic sedimentation in the DeSoto Canyon Salt basin, northeastern Gulf of Mexico. Application of simplified isostatic principles using a lithospheric buoyancy model allow quantification of total tectonic subsidence, crustal thickness, crustal extension, and crust type. An average crustal thickness of 25 km and crustal extension [beta] values between 1.4 and 1.8 suggest the sedimentary succession is underlain by moderately stretched and attenuated continental crust. The widespread distribution and geometry of dipping subsalt reflectors, particularly in the shelfal areas, provide evidence for a Late Triassic-Early Jurassic phase of rifting prior to deposition of Middle Jurassic salt. Although deposition occurred in a slowly subsiding, stable marginal setting, salt movement and associated growth faulting are the most significant tectonic elements affecting the stratigraphic and structural development of the overlying strata.

  16. 藏北高原双湖地区中侏罗统海相油页岩生物 标志化合物分布特征及其意义%Characteristics of Biomarker Compounds and Its Implication of Middle Jurassic Oil Shale Sequence in Shuanghu Area, Northern Tibet Plateau

    Institute of Scientific and Technical Information of China (English)

    林金辉; 伊海生; 李勇; 王成善; 彭平安

    2001-01-01

    Abundant biomarkers, including n-alkanes, isoprenoid, steranes and terpanes, ha v e been detected by GC-MS from the middle Jurassic oil shales in the Shuanghu ar ea, n orthern Tibet plateau.N-alkanes contain carbon number nC12-nC 35 with a relativel y wide range,nC15, nC16 or nC17 as the highest pea k. Examination of the relative abundance show a dominance of low carbon molecular components in the n-alkane . Pr/Ph ratio in oil shales range from 0.77 to 1.59, and it fluctuates in the vert ical section. The upper and lower part of the oil shales have slight predominanc e of pristane, whereas phytane dominates in the middle part of the oil shale seq uence. C30-hopane is the most abundant in the hopane series. According to the relat ively abundance, pentacyclic triterpane > tricyclic terpane > quartcyclic terpan e. Sterane ΣC27/ΣC29 ratio ranges from 0.79 to 1.20, and Σ(C2 7+C28) > ΣC29. The carbon number distribution of the steranes show a slight predominance of C 27 components over C29 in the lower part of the oil shales and a slight domi nance of C29 component over C27 in the upper part of the oil shales sequen ce. C27-dias terane/ C27-sterane ratio range from 0.51 to 3.63, which also fluctuate in the v ertical section. It indicates organic matter of algael origin, with proper ratio contribution from terrestrial sources. The organic matter in the oil shales is mature. Different Pr/Ph and C27-diasteranes/C27-steranes proved e specially usefu l in assessing variation in depositional environment and recognizing preservatio n potential of the organic matter.%重点报道了藏北双湖地区中侏罗统海相油页岩的生物标志化合物特征,首次在该层位油页岩中检出丰富的正烷烃、类异戊二烯烷烃、萜类化合物及甾类化合物。正烷烃图谱呈单峰形,nC15、nC16或nC17为主峰碳,轻烃组份占有绝对优势,OEP值0.93~1.01,无明显的奇偶碳数优势分布;Pr/Ph值为0.77~1.59,在剖面序列中呈波

  17. The Jurassic of Denmark and Greenland: The Jurassic of Skåne, southern Sweden

    Directory of Open Access Journals (Sweden)

    Sivhed, Ulf

    2003-10-01

    Full Text Available In Sweden, Jurassic strata are restricted to Skåne and adjacent offshore areas. Jurassic sedimentary rocks predominantly comprise sandy to muddy siliciclastics, with subordinate coal beds andfew carbonate-rich beds. During Mesozoic times, block-faulting took place in the Sorgenfrei–Tornquist Zone, a tectonic zone which transects Skåne in a NW–SE direction. The Jurassic depositionalenvironments in Skåne were thus strongly influenced by uplift and downfaulting, and to some extent by volcanism. Consequently, the sedimentary record reveals evidence of numerous transgressions, regressions and breaks in sedimentation. Relative sea-level changes played a significant role in controlling the facies distribution, as deposition mainly took place in coastal plain to shallow shelf environments.The alluvial deposits in Skåne include floodplain palaeosols, autochthonous coals, overbank sandstones, and stream channel pebbly sandstones. Restricted marine strata comprise intertidalheteroliths with mixed freshwater and marine trace fossil assemblages, and intertidal delta distributary channel sandstones. Shallow marine sediments encompass subtidal and shoreface sandstoneswith herringbone structures, and bioturbated mudstones with tempestite sandstones. Offshore deposits typically comprise extensively bioturbated muddy sandstones.Floral remains, palaeopedology, clay mineralogy and arenite maturity indicate a warm and humid climate in Skåne throughout the Jurassic, possibly with slightly increasing aridity towards the end of the period. Most Jurassic strata in Skåne have been subjected to mild burial diagenesis, and the petroleum generative window has rarely been reached.

  18. The Jurassic of Denmark and Greenland: The Upper Jurassic of Europe: its subdivision and correlation

    Directory of Open Access Journals (Sweden)

    Zeiss, Arnold

    2003-10-01

    Full Text Available In the last 40 years, the stratigraphy of the Upper Jurassic of Europe has received much attention and considerable revision; much of the impetus behind this endeavour has stemmed from the work of the International Subcommission on Jurassic Stratigraphy. The Upper Jurassic Series consists of three stages, the Oxfordian, Kimmeridgian and Tithonian which are further subdivided into substages, zones and subzones, primarily on the basis of ammonites. Regional variations between the Mediterranean, Submediterranean and Subboreal provinces are discussed and correlation possibilities indicated. The durations of the Oxfordian, Kimmeridgian and Tithonian Stages are reported to have been 5.3, 3.4 and 6.5 Ma, respectively. This review of the present status of Upper Jurassic stratigraphy aids identification of a number of problems of subdivision and definition of Upper Jurassic stages; in particular these include correlation of the base of the Kimmeridgian and the top of the Tithonian between Submediterranean and Subboreal Europe. Although still primarily based on ammonite stratigraphy, subdivision of the Upper Jurassic is increasingly being refined by the incorporation of other fossil groups; these include both megafossils, such as aptychi, belemnites, bivalves, gastropods, brachiopods, echinoderms, corals, sponges and vertebrates, and microfossils such as foraminifera, radiolaria, ciliata, ostracodes, dinoflagellates, calcareous nannofossils, charophyaceae, dasycladaceae, spores and pollen. Important future developments will depend on the detailed integration of these disparate biostratigraphic data and their precise combination with the abundant new data from sequence stratigraphy, utilising the high degree of stratigraphic resolution offered by certain groups of fossils. This article also contains some notes on the recent results of magnetostratigraphy and sequence chronostratigraphy.

  19. Upper Jurassic basin axial turbidites within the Gertrud Graben, Danish Central Graben

    Energy Technology Data Exchange (ETDEWEB)

    Rasmussen, E.S.; Jepsen, A.M.; Maver, K.G.

    1998-10-01

    Fore more than twenty years, the Jurassic succession in the Danish Central Graben has been subject to intense exploration for hydrocarbons. Approximately 43 wildcats have been drilled and most of these tested were structural traps located on footwall crests. The reservoirs encountered were Middle and Upper Jurassic sandstones deposited mainly in near shore depositional environments. Some of these wells penetrated thin turbidites of Late Jurassic to Early Cretaceous age. Within the Gertrud Graben distinct seismic anomalies indicate the presence of basin floor turbidites, which can be correlated to fan fringe turbites encountered in the Jeppe-1, Gwen-2 and Mona-1 wells. Within the Gertrud Graben, seismic anomalies characterized by high amplitude reflections with in an otherwise transparent reflection pattern have been recognized. The zone with high amplitude reflections correlates with thin turbidites with oil shows encountered in the Jeppe-1 well. The turbiditic sandstone succession has a gross thickness of 25 m and a net to gross of 75%, with porosity up to 10%. The presence of oil shows in the thin turbiditic sandstones in the Jeppe-1 well, drilled on a footwall crest, suggests the possibility of thicker sandstones in the basinal areas. The aim of this study is to map the distribution of the seismic anomalies by performing seismic inversion. Seismic inversion is used to derive acoustic impedance as a lithology indicator and to establish a geological model that is a likely prediction of the lithology and architecture of the depositional system. (EG) 2 fig., 17 refs.

  20. Discovery of a short-necked sauropod dinosaur from the Late Jurassic period of Patagonia.

    Science.gov (United States)

    Rauhut, Oliver W M; Remes, Kristian; Fechner, Regina; Cladera, Gerardo; Puerta, Pablo

    2005-06-01

    Sauropod dinosaurs are one of the most conspicuous groups of Mesozoic terrestrial vertebrates. They show general trends towards an overall increase in size and elongation of the neck, by means of considerable elongation of the length of individual vertebrae and a cervical vertebra count that, in some cases, increases to 19 (ref. 1). The long neck is a particular hallmark of sauropod dinosaurs and is usually regarded as a key feeding adaptation. Here we describe a new dicraeosaurid sauropod, from the latest Jurassic period of Patagonia, that has a particularly short neck. With a neck that is about 40% shorter than in other known dicraeosaurs, this taxon demonstrates a trend opposite to that seen in most sauropods and indicates that the ecology of dicraeosaurids might have differed considerably from that of other sauropods. The new taxon indicates that there was a rapid radiation and dispersal of dicraeosaurids in the Late Jurassic of the Southern Hemisphere, after the separation of Gondwana from the northern continents by the late Middle Jurassic.

  1. Ammonoid discoveries in the Antimonio Formation, Sonora, Mexico: new constraints on the Triassic Jurassic boundary

    Science.gov (United States)

    González-León, C. M.; Stanley, G. D.; Taylor, D. G.

    2000-11-01

    The Triassic-Jurassic systemic boundary was recently reported in the middle part of the Antimonio Formation, northwestern Sonora, where five informal sedimentary packages were delineated and characteristic ammonoid faunas were used to establish age control within the succession. The boundary was suggested to lie within the middle part of the 24 m-thick package 4, in relatively unfossiliferous and organic-rich, laminated clay-silt mudstone. Despite the absence of diagnostic Hettangian fossils above the postulated boundary interval, its existence was predicted on characteristic uppermost Triassic Crickmayi Zone Choristoceras ammonoids occurring below in package 3 and upper Hettangian to lower Sinemurian (Badouxia Zone) ammonoids found above in package 5. Recent field investigations yielded new ammonoids of the uppermost Triassic Crickmayi Zone, which are described herein. They are assigned to Choristoceras cf. C. nobile Mojsisovics and Rhabdoceras cf. R. suessi Hauer. These characteristic ammonoids occur within the middle and top of package 4. Their discovery along with other stratigraphic evidence necessitates a revision of the boundary and recognition of a previously unrealized unconformity at the Triassic-Jurassic boundary in Sonora. A revised sea-level curve is necessary to account for these new stratigraphic and paleontological findings.

  2. Paleoclimatology indicators of the Salt Wash member of the Upper Jurassic Morrison Formation near Jensen, Utah

    Energy Technology Data Exchange (ETDEWEB)

    Medlyn, D.A. (Utah State Univ., Logan, UT (United States). Dept. of Geology); Bilbey, S.A. (Utah Field House of Natural History State Park, Vernal, UT (United States))

    1993-04-01

    The Upper Jurassic Morrison Formation has yielded one of the richest floras of the so-called transitional conifers'' of the Middle Mesozoic. Recently, a silicified axis of one of these conifers was collected from the Salt Wash member in essentially the same horizon as a previously reported partial Stegosaurus skeleton. In addition, two other axes of conifers were collected in the same immediate vicinity. Paleoecological considerations are extrapolated from the coniferous flora, vertebrate fauna and associated lithologies. Techniques of paleodendrology and relationships of extant/extinct environments are compared. The paleoclimatic conditions of the transitional conifers and associated dinosaurian fossils are postulated.

  3. New Jurassic Fossil True Bugs of the Pachymeridiidae (Hemiptera:Pentatomomorpha) from Northeast China

    Institute of Scientific and Technical Information of China (English)

    YAO Yunzhi; CAI Wanzhi; REN Dong

    2008-01-01

    Four new fossil genera and species of true bugs from the family Pachymeridiidae,Beipiaocoris multifurcus, Bellicoris mirabilis, Nitoculus regillus, and Viriosinervis stolidus, are described. New specimens were collected from the Middle and Upper Jurassic non-marine sedimentary strata from the Jiulongshan and Yixian Formations of northeast China. The species Karatavocoris asiatica Becker-Migdisova, 1963, which was considered to be a member of the family Coreidae is transferred to the Pachymeridiidae. A new map of all known and newly discovered fossil pachymeridiid localities is given. The diagnosis of the family is modified.

  4. Andean Basin Evolution Associated with Hybrid Thick- and Thin-Skinned Deformation in the Malargüe Fold-Thrust Belt, Western Argentina

    Science.gov (United States)

    Horton, B. K.; Fuentes, F.

    2015-12-01

    Andean deformation and basin evolution in the Malargüe fold-thrust belt of western Argentina (34-36°S) has been dominated by basement faults influenced by pre-existing Mesozoic rift structures of the hydrocarbon-rich Neuquen basin. However, the basement structures diverge from classic inversion structures, and the associated retroarc basin system shows a complex Mesozoic-Cenozoic history of mixed extension and contraction, along with an enigmatic early Cenozoic stratigraphic hiatus. New results from balanced structural cross sections (supported by industry seismic, well data, and surface maps), U-Pb geochronology, and foreland deposystem analyses provide improved resolution to examine the duration and kinematic evolution of Andean mixed-mode deformation. The basement structures form large anticlines with steep forelimbs and up to >5 km of structural relief. Once the propagating tips of the deeper basement faults reached cover strata, they fed slip to shallow thrust systems that were transported in piggyback fashion by newly formed basement structures, producing complex structural relationships. Detrital zircon U-Pb ages for the 5-7 km-thick basin fill succession reveal shifts in sedimentation pathways and accumulation rates consistent with (1) local basement sources during Early-Middle Jurassic back-arc extension, (2) variable cratonic and magmatic arc sources during Late Jurassic-Cretaceous postrift thermal subsidence, and (3) Andean arc and thrust-belt sources during irregular Late Cretaceous-Cenozoic shortening. Although pulses of flexural subsidence can be attributed to periods of fault reactivation (inversion) and geometrically linked thin-skinned thrusting, fully developed foreland basin conditions were only achieved in Late Cretaceous and Neogene time. Separating these two contractional episodes is an Eocene-lower Miocene (roughly 40-20 Ma) depositional hiatus within the Cenozoic succession, potentially signifying forebulge passage or neutral to

  5. The Jurassic of Denmark and Greenland: Late Triassic – Jurassic development of the Danish Basin and the Fennoscandian Border Zone, southern Scandinavia

    Directory of Open Access Journals (Sweden)

    Nielsen, Lars Henrik

    2003-10-01

    Full Text Available The continental to marine Upper Triassic – Jurassic succession of the Danish Basin and the Fennoscandian Border Zone is interpreted within a sequence stratigraphic framework, and the evolution of the depositional basin is discussed. The intracratonic Permian–Cenozoic Danish Basin was formed by Late Carboniferous – Early Permian crustal extension followed by subsidence governed primarily by thermal cooling and local faulting. The basin is separated from thestable Precambrian Baltic Shield by the Fennoscandian Border Zone, and is bounded by basement blocks of the Ringkøbing–Fyn High towards the south. In Late Triassic – Jurassic times, the basin was part of the epeiric shallow sea that covered most of northern Europe. The Upper Triassic – Jurassic basin-fill is subdivided into two tectono-stratigraphic units by a basinwide intra-Aalenian unconformity. The Norian – Lower Aalenian succession was formed under relative tectonic tranquillity and shows an overall layer-cake geometry, except for areas with local faults and salt movements.Deposition was initiated by a Norian transgression that led to shallow marine deposition and was accompanied by a gradual climatic change to more humid conditions. Extensive sheets of shoreface sand and associated paralic sediments were deposited during short-lived forced regressions in Rhaetian time. A stepwise deepening and development of fully marine conditions followed in the Hettangian – Early Sinemurian. Thick uniform basinwide mud blankets weredeposited on an open storm-influenced shelf, while sand was trapped at the basin margins. This depositional pattern continued until Late Toarcian – Early Aalenian times when the basin became restricted due to renewed uplift of the Ringkøbing–Fyn High. In Middle Aalenian – Bathonian times, the former basin area was subjected to deep erosion, and deposition became restricted to the fault-bounded Sorgenfrei–Tornquist Zone. Eventually the fault margins

  6. Post-Jurassic mammal-like reptile from the Palaeocene.

    Science.gov (United States)

    Fox, R C; Youzwyshyn, G P; Krause, D W

    1992-07-16

    Mammal-like reptiles of the order Therapsida document the emergence of mammals from more primitive synapsids and are of unique zoological and palaeontological interest on that account. Therapsids, first appearing in the Early Permian, were thought to become extinct in the Middle Jurassic, soon after the Late Triassic origin of mammals. Here, however, we report the discovery of a therapsid from the late Palaeocene, 100 million years younger than the youngest previous occurrence of the order. This discovery nearly doubles the stratigraphic range of therapsids and furnishes their first record from the Cenozoic. The documenting fossils, an incomplete dentary containing three teeth, and four isolated teeth from other, conspecific individuals (Fig. 1), are from the Paskapoo Formation, at Cochrane, Alberta, Canada, from beds yielding a diverse mammalian fauna of early Tiffanian age. These specimens are catalogued in the collections of the University of Alberta Laboratory for Vertebrate Paleontology (UALVP) and provide the basis for a new taxon, as named and described below: (see text)

  7. Argentina Welcomes Chinese Enterprises

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    @@ On July 13,China-Argentina Entrepreneur Luncheon Meeting was held in Beijing.Cristina Fernandez de Kirchner,President of Argentina,Hui Liangyu,Vice Prime Minister of China and Wan Jifei,President of CCPIT attended the meeting.

  8. Medical revolution in Argentina.

    Science.gov (United States)

    Ballarin, V L; Isoardi, R A

    2010-01-01

    The paper discusses the major Argentineans contributors, medical physicists and scientists, in medical imaging and the development of medical imaging in Argentina. The following are presented: history of medical imaging in Argentina: the pioneers; medical imaging and medical revolution; nuclear medicine imaging; ultrasound imaging; and mathematics, physics, and electronics in medical image research: a multidisciplinary endeavor.

  9. Apparent polar wander path for Adria extended by new Jurassic paleomagnetic results from its stable core: Tectonic implications

    Science.gov (United States)

    Márton, Emő; Zampieri, Dario; Ćosović, Vlasta; Moro, Alan; Drobne, Katica

    2017-03-01

    As a continuation of a systematic paleomagnetic research in the northern part of stable Adria, which provided a well-defined apparent polar wander (APW) path for the Cretaceous-Eocene, we present new paleomagnetic results for the Jurassic. These new data were obtained from 15 geographically distributed localities from the Trento platform (eastern Southern Alps) using standard paleomagnetic approach. The Lower Jurassic shallow water carbonates are not considered for tectonic interpretation, due to inconsistent inclinations. The Middle and Upper Jurassic Rosso Ammonitico provided excellent kinematic constraints. With the new Jurassic results, an APW is now defined for Adria for the 167-40 Ma interval. It is well constrained for timing of important changes, like the speed and the sense of rotations. This APW suggests that the CW rotation and southward shift changed to the opposite at 155.1 ± 5.3 Ma, signifying a dramatic change in the life of the Neo-Tethys, from opening to closing. The latter is manifested in fast CCW rotation and northward movement of Adria up to 102.9 ± 2.4 Ma and moderate displacements in the same manner in post-103 Ma times. Combined data sets from stable Istria and the foreland of the Southern Alps point to an approximately 15° CW rotation with respect to Africa at the end of the Cretaceous, and an about 25° in the CCW sense, after the Eocene.

  10. A giant spider from the Jurassic of China reveals greater diversity of the orbicularian stem group

    Science.gov (United States)

    Selden, Paul A.; Shih, ChungKun; Ren, Dong

    2013-12-01

    A large female spider, Nephila jurassica, was described from Middle Jurassic strata of north-east China and placed in the modern genus Nephila (family Nephilidae) on the basis of many morphological similarities, but, as with many ancient fossils, the single specimen lacked synapomorphies of the family (Selden et al. 2011). In order to test the placement within the nephilid phylogenetic tree, Kuntner et al. (2013) calibrated the molecular phylogeny using N. jurassica in three different scenarios based on inferred mitochondrial substitution rates. They concluded that N. jurassica fitted better as a stem orbicularian than a nephilid. Now, a giant male spider has been discovered at the same locality that yielded N. jurassica. The two sexes are considered conspecific based on their similar morphological features, size, and provenance. The male cannot be accommodated in Nephilidae because of its pedipalp morphology, so the new genus Mongolarachne and family Mongolarachnidae are erected for the species. Comparison with possibly related families show that Mongolarachnidae is most likely on the orbicularian stem, close to other cribellate orbicularians (e.g., Deinopoidea), which suggests a greater diversity of cribellate orbicularians during the Middle Jurassic.

  11. A new ophthalmosaurid ichthyosaur from the Late Jurassic of Owadów-Brzezinki Quarry, Poland

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    Daniel Tyborowski

    2016-12-01

    Full Text Available A new Late Jurassic ophthalmosaurid ichthyosaur Cryopterygius kielanae sp. nov. is described from carbonate deposits of Owadów-Brzezinki Quarry, Central Poland, corresponding in age to the Agardhfjellet Formation (Tithonian, Middle Volgian of the Svalbard Archipelago. The new species is represented by three-dimensionally preserved bones which display several features characteristic for Cryopterygius; including appendicular skeleton, pectoral girdle and perhaps neural arches. The morphology of the Polish form is distinct enough from Cryopterygius kristiansenae from the Svalbard Archipelago to warrant erection of a new species. The size of the bones of Cryopterygius kielanae sp. nov. indicates that this species was smaller than the type species. Its diagnostic anatomical features include a humerus with prominent and well developed dorsal process located in the middle of the dorsal surface of the bone, prominent deltopectoral crest, relatively broad femur and absence of the wide groove on the quadrate articular condyle. The discovery of a new ophthalmosaurid ichthyosaur of the genus Cryopterygius in Poland suggests that the Owadów-Brzezinki area was a transition zone between the tropical Tethys Ocean and the Arctic basin during the Late Jurassic.

  12. A Jurassic avialan dinosaur from China resolves the early phylogenetic history of birds.

    Science.gov (United States)

    Godefroit, Pascal; Cau, Andrea; Dong-Yu, Hu; Escuillié, François; Wenhao, Wu; Dyke, Gareth

    2013-06-20

    The recent discovery of small paravian theropod dinosaurs with well-preserved feathers in the Middle-Late Jurassic Tiaojishan Formation of Liaoning Province (northeastern China) has challenged the pivotal position of Archaeopteryx, regarded from its discovery to be the most basal bird. Removing Archaeopteryx from the base of Avialae to nest within Deinonychosauria implies that typical bird flight, powered by the forelimbs only, either evolved at least twice, or was subsequently lost or modified in some deinonychosaurians. Here we describe the complete skeleton of a new paravian from the Tiaojishan Formation of Liaoning Province, China. Including this new taxon in a comprehensive phylogenetic analysis for basal Paraves does the following: (1) it recovers it as the basal-most avialan; (2) it confirms the avialan status of Archaeopteryx; (3) it places Troodontidae as the sister-group to Avialae; (4) it supports a single origin of powered flight within Paraves; and (5) it implies that the early diversification of Paraves and Avialae took place in the Middle-Late Jurassic period.

  13. Astronomy in Argentina

    CERN Document Server

    Muriel, Hernán

    2013-01-01

    This article analyses the current state of Astronomy in Argentina and describes its origins. We briefly describe the institutions where astronomical research takes place, the observational facilities available, the training of staff and professionals, and the role of the institutions in scientific promotion. We also discuss the outreach of Astronomy towards the general public, as well as amateur activities. The article ends with an analysis of the future prospects of astronomy in Argentina.

  14. JURASSIC SEDIMENTARY AND TECTONIC PROCESSES AT MONTAGNA GRANDE (TRAPANESE DOMAIN, WESTERN SICILY, ITALY

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    LUCA MARTIRE

    2004-03-01

    Full Text Available The Rosso Ammonitico of the Montagna Grande area is very interesting because of the great diversification in facies and thickness in three very closely situated sections. The Jurassic succession in this area is that typical of the Trapanese Domain. It starts with a thick pile of platform limestones (Inici Formation: Hettangian - Sinemurian that are overlain by typically condensed and commonly nodular pelagic limestones (Rosso Ammonitico: Middle Jurassic - lowermost Cretaceous. The good exposure of this succession in active quarries allows observation of sedimentological and palaeontological details and to improve the understanding of the Jurassic tectono-sedimentary evolution. The Rocca chi Parra quarry shows a stepped surface, with a relief of some metres, incised in the Inici Formation. It is covered by lenticular or wedge-shaped lithosomes a few metres-thick of highly condensed Rosso Ammonitico. It is interpreted as a slide scar along which a thin but extensive block of lithified platform limestones was detached and slid downslope. The Poggio Roccione quarry shows neptunian sills and collapse structures in the middle part of the Rosso Ammonitico that on the whole is thicker (about 12 m than at Rocca chi Parra. They indicate sea-floor instability probably due to seismic shocks with brittle to plastic behaviour of sediments depending on their coherence. The Montagna Grande outcrop shows an even thicker succession which includes a wedge of cherty limestones about 10 m thick intercalated between a lower and an upper Rosso Ammonitico calcareous unit. The features described in these three sections document a highly irregular sea-floor topography which in turn was controlled by several phases of extensional tectonics during Mid and Late Jurassic pelagic sedimentation. Structurally higher sectors closer to fault scarps were affected by a very condensed sedimentation, the opening of subvertical dykes and the triggering of large slides. Structurally

  15. The Jurassic of Denmark and Greenland: The Jurassic of East Greenland: a sedimentary record of thermal subsidence, onset and culmination of rifting

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    Surlyk, Finn

    2003-10-01

    Full Text Available The Late Palaeozoic – Mesozoic extensional basin complex of East Greenland contains a record of deposition during a period of Rhaetian – Early Bajocian thermal subsidence, the onset of riftingin the Late Bajocian, its growth during the Bathonian–Kimmeridgian, culmination of rifting in the Volgian – Early Ryazanian, and waning in the Late Ryazanian – Hauterivian. The area was centred over a palaeolatitude of about 45°N in the Rhaetian and drifted northwards to about 50°N in the Hauterivian. A major climate change from arid to humid subtropical conditions took place at the Norian–Rhaetian transition. Deposition was in addition governed by a long-term sea-level rise with highstands in the Toarcian–Aalenian, latest Callovian and Kimmeridgian, and lowstands in the latest Bajocian – earliest Bathonian, Middle Oxfordian and Volgian.The Rhaetian – Lower Bajocian succession is considered the upper part of a megasequence, termed J1, with its base in the upper Lower Triassic, whereas the Upper Bajocian – Hauterivian succession forms a complete, syn-rift megasequence, termed J2. The southern part of the basin complex in Jameson Land contains a relatively complete Rhaetian–Ryazanian succession and underwent only minor tilting during Middle Jurassic – earliest Cretaceous rifting. Rhaetian – Lower Jurassic deposits are absent north of Jameson Land and this region was fragmented into strongly tilted fault blocks during the protracted rift event. The syn-rift successions of the two areas accordingly show different long-term trends in sedimentary facies. In the southern area, the J2 syn-rift megasequence forms a symmetrical regressive–transgressive–regressive cycle, whereas the J2 megasequence in the northern area shows an asymmetrical, stepwise deepening trend.A total of eight tectonostratigraphic sequences are recognised in the Rhaetian–Hauterivian interval. They reflect major changes in basin configuration, drainage systems

  16. Helosis (Balanophoraceae en Argentina Helosis (Balanophoraceae in Argentina

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    José Luis Fontana

    2006-07-01

    Full Text Available Se cita por primera vez para Argentina Helosis cayennensis (Swartz Sprengel var. cayennensis en base a colecciones hechas por los autores en la Isla argentina de Apipé Grande, Ituzaingó, provincia de Corrientes. Se describe e ilustra la especie, el desarrollo de la planta y su estado de conservación. Esta cita de Helosis corresponde a un género nuevo para la flora argentina.Helosis cayennensis var. cayennensis is reported for the first time for Argentina. The species is described and ilustrated. Developement and ecology are also given. Helosis is also a new generic record for Argentina.

  17. Taphonomy and paleoecology inferences of vertebrate ichnofossils from Guará Formation (Upper Jurassic), southern Brazil

    Science.gov (United States)

    Dentzien-Dias, Paula C.; Schultz, Cesar L.; Bertoni-Machado, Cristina

    2008-03-01

    In southern Brazil, the eolian facies of the Guará Formation (Late Jurassic) reveal footprints and trackways of vertebrates (dinosaurs), as well as burrows made by small vertebrates. All the footprints and trackways are preserved in dunes and sand sheets. The footprints made in the sand sheets are not well preserved due to intense trampling and can be distinguished only by the deformation of the sandstone laminations. In some cases it is possible to see this deformation in plan and in section. Tracks of theropods, ornithopods and middle-sized sauropods are present. Two footprints preserved in the foreset of a paleodune permitted recognition of slide structures and identification of the trackmaker, a theropod. Burrows horizontally across the foresets were found at this same paleodune. Ribbons of massive sandstone - interpreted as the partial filling of the base of the burrows - covered by little blocks of stratified sandstone - suggest the collapse of the burrow roof inward. There are no body fossils in the Guará Formation, consequently the preservation of these tracks provides unique evidence of widespread dinosaurs activity in southern Brazil near the end of the Jurassic.

  18. Schmeissneria: An angiosperm from the Early Jurassic

    Institute of Scientific and Technical Information of China (English)

    Xin WANG

    2010-01-01

    The origin of angiosperms has been a focus of intensive research for a long time. The so-called preCretaceous angiosperms, including Schmeissneria, are usually clouded with doubt. To expel the cloud around the enigmatic Schmeissneria, the syntype and new materials of Schmeissneria collected previously in Germany and recently in China are studied. These materials include female inflorescences and infructescences. The latter are old materials but were under-studied previously. Light microscopy and scanning electron microscope observations indicate that the fruits in these infructescences have in situ seeds enclosed, and that the ovaries are closed before pollination. Thus the plants meet two strict criteria for angiosperms: angiospermy plus angio-ovuly. Placing Schmeissneria in angiosperms will extend the record of angiosperms up to the Early Jurassic, more compatible with many molecular dating conclusions on the age of angiosperms, and demanding a reassessment of the current doctrines on the origin of angiosperms. Although the phylogenetic relationship of Schmeissneria to other angiosperms apparently is still an open question, this study adds to research concerning the origin of angiosperms.

  19. New dinosaur (Theropoda, stem-Averostra) from the earliest Jurassic of the La Quinta formation, Venezuelan Andes.

    Science.gov (United States)

    Langer, Max C; Rincón, Ascanio D; Ramezani, Jahandar; Solórzano, Andrés; Rauhut, Oliver W M

    2014-10-01

    Dinosaur skeletal remains are almost unknown from northern South America. One of the few exceptions comes from a small outcrop in the northernmost extension of the Andes, along the western border of Venezuela, where strata of the La Quinta Formation have yielded the ornithischian Laquintasaura venezuelae and other dinosaur remains. Here, we report isolated bones (ischium and tibia) of a small new theropod, Tachiraptor admirabilis gen. et sp. nov., which differs from all previously known members of the group by an unique suite of features of its tibial articulations. Comparative/phylogenetic studies place the new form as the sister taxon to Averostra, a theropod group that is known primarily from the Middle Jurassic onwards. A new U-Pb zircon date (isotope dilution thermal-ionization mass spectrometry; ID-TIMS method) from the bone bed matrix suggests an earliest Jurassic maximum age for the La Quinta Formation. A dispersal-vicariance analysis suggests that such a stratigraphic gap is more likely to be filled by new records from north and central Pangaea than from southern areas. Indeed, our data show that the sampled summer-wet equatorial belt, which yielded the new taxon, played a pivotal role in theropod evolution across the Triassic-Jurassic boundary.

  20. New dinosaur (Theropoda, stem-Averostra) from the earliest Jurassic of the La Quinta formation, Venezuelan Andes

    Science.gov (United States)

    Langer, Max C.; Rincón, Ascanio D.; Ramezani, Jahandar; Solórzano, Andrés; Rauhut, Oliver W. M.

    2014-01-01

    Dinosaur skeletal remains are almost unknown from northern South America. One of the few exceptions comes from a small outcrop in the northernmost extension of the Andes, along the western border of Venezuela, where strata of the La Quinta Formation have yielded the ornithischian Laquintasaura venezuelae and other dinosaur remains. Here, we report isolated bones (ischium and tibia) of a small new theropod, Tachiraptor admirabilis gen. et sp. nov., which differs from all previously known members of the group by an unique suite of features of its tibial articulations. Comparative/phylogenetic studies place the new form as the sister taxon to Averostra, a theropod group that is known primarily from the Middle Jurassic onwards. A new U–Pb zircon date (isotope dilution thermal-ionization mass spectrometry; ID-TIMS method) from the bone bed matrix suggests an earliest Jurassic maximum age for the La Quinta Formation. A dispersal–vicariance analysis suggests that such a stratigraphic gap is more likely to be filled by new records from north and central Pangaea than from southern areas. Indeed, our data show that the sampled summer-wet equatorial belt, which yielded the new taxon, played a pivotal role in theropod evolution across the Triassic–Jurassic boundary. PMID:26064540

  1. New ophthalmosaurid ichthyosaurs from the European Lower Cretaceous demonstrate extensive ichthyosaur survival across the Jurassic-Cretaceous boundary.

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    Valentin Fischer

    Full Text Available BACKGROUND: Ichthyosauria is a diverse clade of marine amniotes that spanned most of the Mesozoic. Until recently, most authors interpreted the fossil record as showing that three major extinction events affected this group during its history: one during the latest Triassic, one at the Jurassic-Cretaceous boundary (JCB, and one (resulting in total extinction at the Cenomanian-Turonian boundary. The JCB was believed to eradicate most of the peculiar morphotypes found in the Late Jurassic, in favor of apparently less specialized forms in the Cretaceous. However, the record of ichthyosaurs from the Berriasian-Barremian interval is extremely limited, and the effects of the end-Jurassic extinction event on ichthyosaurs remains poorly understood. METHODOLOGY/PRINCIPAL FINDINGS: Based on new material from the Hauterivian of England and Germany and on abundant material from the Cambridge Greensand Formation, we name a new ophthalmosaurid, Acamptonectes densus gen. et sp. nov. This taxon shares numerous features with Ophthalmosaurus, a genus now restricted to the Callovian-Berriasian interval. Our phylogenetic analysis indicates that Ophthalmosauridae diverged early in its history into two markedly distinct clades, Ophthalmosaurinae and Platypterygiinae, both of which cross the JCB and persist to the late Albian at least. To evaluate the effect of the JCB extinction event on ichthyosaurs, we calculated cladogenesis, extinction, and survival rates for each stage of the Oxfordian-Barremian interval, under different scenarios. The extinction rate during the JCB never surpasses the background extinction rate for the Oxfordian-Barremian interval and the JCB records one of the highest survival rates of the interval. CONCLUSIONS/SIGNIFICANCE: There is currently no evidence that ichthyosaurs were affected by the JCB extinction event, in contrast to many other marine groups. Ophthalmosaurid ichthyosaurs remained diverse from their rapid radiation in the Middle

  2. Conchostracans as evidence of Jurassic levels in the Caturrita Formation, Faxinal do Soturno, Rio Grande do Sul, Brazi

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    Rosemarie Rohn

    2014-03-01

    Full Text Available This paper focus on the first conchostracans (Crustacea, Spinicaudata found at the São Luís outcrop (Caturrita Formation, Rosário do Sul Group, in Faxinal do Soturno, Rio Grande do Sul State, Brazil (29º33’ 29.09”S, 53º 26’ 54”W. Fossil vertebrates and plants identified at this outcrop suggest conflicting ages, respectively Late Triassic and Early Jurassic. Dinosaur tracks recently found at the upper part of the outcrop enhance these age problems. In this way, the conchostracans constitute important additional elements in this discussion. Some specimens share many characteristics with Carapacestheria disgregaris (Tasch Shen (Eosestheriidae of the Ferrar Group, Lower-Mid Jurassic of the Transantartic Mountains. But differences in the ornamentation details led to the proposal of a new genus and a new species, Nothocarapacestheria soturnensis , and to the interpretation of a close phylogenetic relationship with the Antarctic species. Other samples in this assemblage are similar to Australestheria corneti (Marliére Chen (Fushunograptidae of the Middle Jurassic from Zaire. Together, these conchostracans substantiate a Jurassic age and corroborate the data of the Bennettitales flora found at the same levels in the outcrop. However, the Late Triassic age indicated by the tetrapods cannot be discarded according to their lower stratigraphic position in São Luís outcrop. In the same way, the present chronostratigraphic discussion does not apply to the other occurrences of the Caturrita Formation, especially because the correlations between outcrops are extremely difficult, both by the lack of paleontological support and by the numerous faultings during the Mesozoic sedimentation in the southern part of the Paraná Basin.

  3. A new primitive Neornithischian dinosaur from the Jurassic of Patagonia with gut contents

    Science.gov (United States)

    Salgado, Leonardo; Canudo, José I.; Garrido, Alberto C.; Moreno-Azanza, Miguel; Martínez, Leandro C. A.; Coria, Rodolfo A.; Gasca, José M.

    2017-02-01

    We describe a new species of an ornithischian dinosaur, Isaberrysaura mollensis gen. et sp. nov. The specimen, consisting in an almost complete skull and incomplete postcranium was collected from the marine-deltaic deposits of the Los Molles Formation (Toarcian-Bajocian), being the first reported dinosaur for this unit, one of the oldest from Neuquén Basin, and the first neornithischian dinosaur known from the Jurassic of South America. Despite showing a general stegosaurian appearance, the extensive phylogenetic analysis carried out depicts Isaberrysaura mollensis gen. et sp. nov. as a basal ornithopod, suggesting that both Thyreophora and neornithischians could have achieved significant convergent features. The specimen was preserved articulated and with some of its gut content place in the middle-posterior part of the thoracic cavity. Such stomach content was identified as seeds, most of them belonging to the Cycadales group. This finding reveals a possible and unexpected role of this ornithischian species as seed-dispersal agent.

  4. A lab in Argentina

    Science.gov (United States)

    2016-06-01

    Mauricio Erben, a researcher at the National University of La Plata and the National Scientific and Technical Research Council, talks to Nature Chemistry about his experience of research in Argentina, and how it is inherently linked to the country's political climate.

  5. Mathematics Education in Argentina

    Science.gov (United States)

    Varsavsky, Cristina; Anaya, Marta

    2009-01-01

    This article gives an overview of the state of mathematics education in Argentina across all levels, in the regional and world contexts. Statistics are drawn from Mercosur and UNESCO data bases, World Education Indicators and various national time-series government reports. Mathematics results in national testing programmes, Programme for…

  6. Albert Einstein visits Argentina

    CERN Document Server

    Gangui, A; Gangui, Alejandro; Ortiz, Eduardo L.

    2005-01-01

    This is a detailed, day by day, account of Albert Einstein's activities, both social and scientific, during his 30-day stay in Argentina in 1925, including his lectures on relativity at the various local universities and his visit to the National Academy of Sciences, as follows from his personal Diary of the trip to South-America and other contemporary documents.

  7. A Jurassic pterosaur from Patagonia and the origin of the pterodactyloid neurocranium

    Science.gov (United States)

    Codorniú, Laura; Paulina Carabajal, Ariana; Unwin, David; Rauhut, Oliver W.M.

    2016-01-01

    Pterosaurs are an extinct group of highly modified flying reptiles that thrived during the Mesozoic. This group has unique and remarkable skeletal adaptations to powered flight, including pneumatic bones and an elongate digit IV supporting a wing-membrane. Two major body plans have traditionally been recognized: the primitive, primarily long-tailed paraphyletic “rhamphorhynchoids” (preferably currently recognized as non-pterodactyloids) and the derived short-tailed pterodactyloids. These two groups differ considerably in their general anatomy and also exhibit a remarkably different neuroanatomy and inferred head posture, which has been linked to different lifestyles and behaviours and improved flying capabilities in these reptiles. Pterosaur neuroanatomy, is known from just a few three-dimensionally preserved braincases of non-pterodactyloids (as Rhamphorhynchidae) and pterodactyloids, between which there is a large morphological gap. Here we report on a new Jurassic pterosaur from Argentina, Allkaruen koi gen. et sp. nov., remains of which include a superbly preserved, uncrushed braincase that sheds light on the origins of the highly derived neuroanatomy of pterodactyloids and their close relatives. A µCT ray-generated virtual endocast shows that the new pterosaur exhibits a mosaic of plesiomorphic and derived traits of the inner ear and neuroanatomy that fills an important gap between those of non-monofenestratan breviquartossans (Rhamphorhynchidae) and derived pterodactyloids. These results suggest that, while modularity may play an important role at one anatomical level, at a finer level the evolution of structures within a module may follow a mosaic pattern. PMID:27635315

  8. A Jurassic pterosaur from Patagonia and the origin of the pterodactyloid neurocranium

    Directory of Open Access Journals (Sweden)

    Laura Codorniú

    2016-08-01

    Full Text Available Pterosaurs are an extinct group of highly modified flying reptiles that thrived during the Mesozoic. This group has unique and remarkable skeletal adaptations to powered flight, including pneumatic bones and an elongate digit IV supporting a wing-membrane. Two major body plans have traditionally been recognized: the primitive, primarily long-tailed paraphyletic “rhamphorhynchoids” (preferably currently recognized as non-pterodactyloids and the derived short-tailed pterodactyloids. These two groups differ considerably in their general anatomy and also exhibit a remarkably different neuroanatomy and inferred head posture, which has been linked to different lifestyles and behaviours and improved flying capabilities in these reptiles. Pterosaur neuroanatomy, is known from just a few three-dimensionally preserved braincases of non-pterodactyloids (as Rhamphorhynchidae and pterodactyloids, between which there is a large morphological gap. Here we report on a new Jurassic pterosaur from Argentina, Allkaruen koi gen. et sp. nov., remains of which include a superbly preserved, uncrushed braincase that sheds light on the origins of the highly derived neuroanatomy of pterodactyloids and their close relatives. A µCT ray-generated virtual endocast shows that the new pterosaur exhibits a mosaic of plesiomorphic and derived traits of the inner ear and neuroanatomy that fills an important gap between those of non-monofenestratan breviquartossans (Rhamphorhynchidae and derived pterodactyloids. These results suggest that, while modularity may play an important role at one anatomical level, at a finer level the evolution of structures within a module may follow a mosaic pattern.

  9. Position of the Triassic-Jurassic boundary and timing of the end-Triassic extinctions on land: Data from the Moenave Formation on the southern Colorado Plateau, USA

    Science.gov (United States)

    Lucas, S.G.; Tanner, L.H.; Donohoo-Hurley, L.; Geissman, J.W.; Kozur, H.W.; Heckert, A.B.; Weems, R.E.

    2011-01-01

    Strata of the Moenave Formation on and adjacent to the southern Colorado Plateau in Utah-Arizona, U.S.A., represent one of the best known and most stratigraphically continuous, complete and fossiliferous terrestrial sections across the Triassic-Jurassic boundary. We present a synthesis of new biostratigraphic and magnetostratigraphic data collected from across the Moenave Formation outcrop belt, which extends from the St. George area in southwestern Utah to the Tuba City area in northern Arizona. These data include palynomorphs, conchostracans and vertebrate fossils (including footprints) and a composite polarity record based on four overlapping magnetostratigraphic sections. Placement of the Triassic-Jurassic boundary in strata of the Moenave Formation has long been imprecise and debatable, but these new data (especially the conchostracans) allow us to place the Triassic-Jurassic boundary relatively precisely in the middle part of the Whitmore Point Member of the Moenave Formation, stratigraphically well above the highest occurrence of crurotarsan body fossils or footprints. Correlation to marine sections based on this placement indicates that major terrestrial vertebrate extinctions preceded marine extinctions across the Triassic-Jurassic boundary and therefore were likely unrelated to the Central Atlantic Magmatic Province (CAMP) volcanism. ?? 2011 Elsevier B.V.

  10. Petrogenesis of early Jurassic basalts in southern Jiangxi Province, South China: Implications for the thermal state of the Mesozoic mantle beneath South China

    Science.gov (United States)

    Cen, Tao; Li, Wu-xian; Wang, Xuan-ce; Pang, Chong-jin; Li, Zheng-xiang; Xing, Guang-fu; Zhao, Xi-lin; Tao, Jihua

    2016-07-01

    Early Jurassic bimodal volcanic and intrusive rocks in southern South China show distinct associations and distribution patterns in comparison with those of the Middle Jurassic and Cretaceous rocks in the area. It is widely accepted that these rocks formed in an extensional setting, although the timing of the onset and the tectonic driver for extension are debated. Here, we present systematic LA-ICP-MS zircon U-Pb ages, whole-rock geochemistry and Sr-Nd isotope data for bimodal volcanic rocks from the Changpu Formation in the Changpu-Baimianshi and Dongkeng-Linjiang basins in southern Jiangxi Province, South China. Zircon U-Pb ages indicate that the bimodal volcanic rocks erupted at ca. 190 Ma, contemporaneous with the Fankeng basalts (~ 183 Ma). A compilation of geochronological results demonstrates that basin-scale basaltic eruptions occurred during the Early Jurassic within a relatively short interval (plate continental mantle setting, such as the Basin and Range Province in western North America. This study provides an important constraint on the Early Jurassic mantle thermal state beneath South China.

  11. Trachyteuthis covacevichi n. sp., a Late Jurassic Palaeopacific coleoid cephalopod

    Directory of Open Access Journals (Sweden)

    D. Fuchs

    2008-02-01

    Full Text Available A new early Oxfordian coleoid cephalopod, Trachyteuthis covacevichi n. sp., is described from northern Chile. It represents the first Late Jurassic Palaeopacific vampyropod and thus considerably extends the palaeogeographic distribution of trachyteuthids. In general, Tr. covacevichi n. sp. possesses a gladius typical for the genus, but wider than in other species. Similarities between Tr. covacevichi n. sp., Tr. palmeri from the Oxfordian of Cuba and Tr. sp. from the Kimmeridgian of Europe confirm a Caribbean Seaway between the Tethys and the Palaeopacific during Late Jurassic times. Morphologically, the wide gladius of Tr. covacevichi n. sp. supports a close phylogenetic relationship between Teudopsis and Trachyteuthis. doi:10.1002/mmng.200700012

  12. The second Jurassic dinosaur rush and the dawn of dinomania.

    Science.gov (United States)

    Brinkman, Paul D

    2010-09-01

    During the second Jurassic dinosaur rush museum paleontologists raced to display the world's first mounted sauropod dinosaur. The American Museum of Natural History triumphed in 1905 when its Brontosaurus debuted before an admiring crowd of wealthy New Yorkers. The Carnegie Museum of Natural History in Pittsburgh, the Field Columbian Museum in Chicago and other institutions were quick to follow with their own sauropod displays. Thereafter, dinomania spread far and wide, and big, showpiece dinosaurs became a museum staple. This brief but intensely competitive period of acquisitiveness fostered important Jurassic dinosaur revisions and crucial innovations in paleontological field and lab techniques.

  13. The Jurassic of East Greenland: a sedimentary record of thermal subsidence, onset and culmination of rifting

    Energy Technology Data Exchange (ETDEWEB)

    Surlyk, F. [Univ. of Copenhagen, Copenhagen (Denmark)]. Geological Inst.

    2003-07-01

    The Late Palaeozoic - Mesozoic extensional basin complex of East Greenland contains a record of deposition during a period of Rhaetian - Early Bajocian thermal subsidence, the onset of rifting in the Late Bajocian, its growth during the Bathonian-Kimmeridgian, culmination of rifting in the Volgian - Early Ryazanian, and waning in the Late Ryazanian - Hauterivian.,The area was centred over a palaeolatitude of about 45 deg C N in the Rhaetian and drifted northwards to about 50 deg C N in the Hauterivian. A major climate change from arid to humid subtropical conditions took place at the Norian-Rhaetian transition. Deposition was in addition governed by a long-term sea-level rise with highstands in the Toarcian-Aalenian, latest Callovian and Kimmeridgian, and lowstands in the latest Bajocian - earliest Bathonian, Middle Oxfordian and Volgian. The Rhaetian - Lower Bajocian succession is considered the upper part of a megasequence, termed Jl, with its base in the upper Lower Triassic, whereas the Upper Bajocian - Hauterivian succession forms a complete, syn-rift megasequence, termed J2. The southem part of the basin complex in Jameson Land contains a relatively complete Rhaetian-Ryazanian succession and underwent only minor tilting during Middle Jurassic - earliest Cretaceous rifting. Rhaetian - Lower Jurassic deposits are absent north of Jameson Land and this region was fragmented into strongly tilted fault blocks during the protracted rift event. The syn-rift successions of the two areas accordingly show different long-term trends in sedimentary facies. In the southern area, the J2 syn-rift megasequence forms a symmetrical regressive-transgressive-regressive cycle, whereas the J2 megasequence in the northem area shows an asymmetrical, stepwise deepening trend. A total of eight tectonostratigraphic sequences are recognised in the Rhaetian-Hauterivian interval. They reflect major changes in basin configuration, drainage systems, sediment transport and distribution

  14. New ages and chemical analysis on Lower Jurassic volcanism close to the dorsal de Huincul, Neuquén

    Directory of Open Access Journals (Sweden)

    Mario SCHIUMA

    2008-12-01

    Full Text Available New single zircon ages from hydrocarbon well cores in the A-1 Norte de la Dorsal and Anticlinal Campamento area of the Neuquén basin indicate that 199.0 ± 1.5 Ma andesite lava flow and 203.75 ± 0.26 Ma dacite breccia overlie a 286.5 ± 2.3 Ma granodiorite and 284.0 ± 1.3 Ma andesite dike. The Lower Jurassic volcanics were deposited on a regional erosion surface affecting the Permian rocks. In the studied area there is no record of Middle to Upper Triassic volcanics as in other areas of the basin. Exotic zircon crystals gave ages of Mesoproterozoic, Middle Cambian, Early Devonian and Early Carboniferous, suggesting a poliphasic basement. Chemical analyses of three selected samples show a calc-alkaline signature, supporting the existence of a volcanic arc at the Early Jurassic as it has been proposed for the center of the basin.

  15. Crustal structure across the Colorado Basin, offshore Argentina

    Science.gov (United States)

    Franke, Dieter; Neben, Soenke; Schreckenberger, Bernd; Schulze, Albrecht; Stiller, Manfred; Krawczyk, Charlotte M.

    2006-06-01

    The geology of the wide shelves surrounding the South Atlantic is closely linked to the kinematics and history of the opening of the ocean. However, several wide sedimentary basins, which developed along the margins show peculiarities that are not yet understood in the context of the evolution of the South Atlantic. The Colorado Basin, a wide sedimentary basin on the broad shelf of Argentina, extends in EW direction. The basin's evolution oblique or orthogonal to the continent-ocean boundary indicates that it is not a product of simple progressive extension and crustal thinning. In addition a basement high, paralleling the continental margin and separating the Colorado Basin from the deep-sea basin is a common interpretation. These findings are hardly in accordance with the idea that the Colorado Basin is an extensional basin that developed in conjunction with the early E-W opening phase of the South Atlantic in the Late Jurassic/Early Cretaceous. The composition, type, and structure of the basement, key points for the evaluation of the basins evolution, are widely speculative. In this context multichannel seismic reflection data from the Argentine Shelf and a 665-km-long onshore-offshore refraction profile, running across the Colorado Basin onto the coast are discussed in combination with gravity data. The stratigraphy for the sedimentary successions was adopted from the literature and the reflection seismic marker horizons formed besides the interval velocities the input for the starting model for refraction seismic traveltime modelling. The modelling strategy was an iterative procedure between refraction seismic traveltime and gravity modelling. The preparation of the density models was coarsely orientated on published velocity-density relations. The modelling results are in favour of a continuation of the main onshore geological features beneath the sedimentary infill of the Colorado Basin. We interpret the basement along the line from west to east as offshore

  16. Regional Seismology in Argentina

    Science.gov (United States)

    1981-05-11

    Historia (Pananerican Institute of Geography and History, sponsored by the Organization of American States: Revista Geoffsica (Geophysical Journal). B...South America and the Recurrence Relation of Earthquakes. Revista Geofisica del Instituto Panamericano do Geograffa • Historia (IPGH), No. 4, June, 155...Underground Explosion, 8-18 September, Oslo, Norway. Universidad Nacional do San Juan, 1979. Informs del Simposio Bi- nacional Argentina-Estados Unidos sobre

  17. Argentina: A Country Study

    Science.gov (United States)

    1983-05-17

    Forundizi stayed in office until March 29, 1962. Skillfully, Frondizi managed partially to revive the economy and set the country on the road toward... Frondizi could not win the support of all sections of the population for a concentrated effort of austerity to save Argentina’s economy from the chaos it...make sacrifices. Frondizi came to grief when the reinstated Peronist Party won control of several provinces and increased its membership in congress in

  18. de la sociedad argentina

    Directory of Open Access Journals (Sweden)

    Diego Galeano

    2007-01-01

    Full Text Available Este artículo trata sobre un período de la historia argentina en el cual la "mirada médica", a través de un grupo de prestigiosos intelectuales, se convirtió en una clave de interpretación de la sociedad argentina. El análisis gira en torno a la obra de uno de los médicos higienistas más influyentes, José María Ramos Mejía, deteniéndose especialmente en su libro más famoso: Las multitudes argentinas (1899. La hipótesis principal que recorre el texto es la siguiente: la medicalización de la sociedad, acentuada luego de las epidemias de cólera y fiebre amarilla de mediados del siglo XIX, ofreció a las elites públicas la posibilidad de construir dominios legítimos de intervención estatal. Intromisiones del Estado en la vida privada que, además de ser algo resistidas por la población, entraban en tensión con los principios teóricos del liberalismo que los propios miembros de la elite defendían.

  19. Optimization of the Acetic Acid method for microfossil extraction from lithified carbonate rocks: Examples from the Jurassic and Miocene of Saudi Arabia

    Science.gov (United States)

    Chan, Septriandi; Malik, Muhammad; Kaminski, Michael; Babalola, Lamidi

    2016-04-01

    We report the first ever use of the acetic acid processing method for the extraction of microfossils from indurated limestones in Saudi Arabia. Two different limestone samples from Middle Jurassic and Middle Miocene formation in Saudi Arabia were tested under different concentrations of acid from 50% to 100% and with processing times from 2 hours to 10 hours, in an attempt to optimize the processing methodology. The recovery of acid residues shows a similar trend for both Jurassic and Miocene samples. The weight percentage of residue particle size > 1 mm decreases as acid concentration increases, especially in the 50 to 80% acid concentration range, and the weight percentage of the smallest size particles >0.063 mm increases as acid concentration increases. The small fraction of residue between 0.50 - 0.063 mm was split into 3 g subsamples and picked for microfossils in order to assess their preservation. All concentrations of acetic acid tested show promising results for both the Jurassic Dhruma and Miocene Dam formation carbonates. Higher acid concentrations with longer reaction times yield better recovery than higher concentrations with less reaction time. Based on our experiment, we recommended a 60% concentration of acetic acid to be the optimal concentration for use on routine micropaleontological samples of Saudi Arabian carbonate rocks. By lowering the concentration of acetic acid from 80% to 60%, the consumption of acid is reduced without compromising the recovery of microfossils, and the sample can be processed in a more environmentally friendly manner.

  20. LA-ICPMS Zircon U-Pb Dating in the Jurassic Daohugou Beds and Correlative Strata in Ningcheng of Inner Mongolia

    Institute of Scientific and Technical Information of China (English)

    LIU Yanxue; LIU Yongqing; ZHANG Hong

    2006-01-01

    LA-ICPMS Zircon U-Pb dating is applied to volcanic rocks overlying and underlying the Salamander-bearing bed in the Daohugou beds of Ningcheng in Inner Mongola and Reshuichang of Lingyuan and Mazhangzi of Jianping in western Liaoning. The results indicate that the youngest age of the rocks in Daohugou of Ningcheng is 158 Ma, and the oldest one is 164 Ma. Synthesized researches indicate that the salamander-bearing beds in Daohugou of Ningcheng, Reshuichang of Lingyuan and Mazhangzi of Jianping were developed in the same period. The Daohugou beds were formed in the geological age of 164-158 Ma of the middle-late Jurassic. Whilst, the Daohugou beds and its correlative strata should correspond to the Tiaojishan Formation (or Lanqi Formation) of the middle Jurassic in northern Hebei Province and western Liaoning Province, based on the disconformity between the Daohugou beds and its overlaying beds of the Tuchengzi Formation of Late Jurassic and the Jehol Beds of early Cretaceous, and the disconformity between the Daohugou Beds and its underlying Jiulongshan Formation, which is composed of conglomerate, sandstone, shale with coal and thin coal beds.

  1. Klukiopsis jurassica--A new Jurassic schizaeaceous fern from China

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A new Jurassic schizaeaceous fern Klukiopsis jurassica gen. et sp. nov. from Yima, Henan Province, China is described. The new fern is characterized by the abaxial sori arranged in two rows, apical and complete annulus and more than 800 smooth trilete spores in each sorus.

  2. Microstructures of Early Jurassic (Toarcian) shales of Northern Europe

    NARCIS (Netherlands)

    Houben, M.E.; Barnhoorn, A.; Wasch, L.; Trabucho-Alexandre, João; Peach, C.J.; Drury, M.R.

    2016-01-01

    The Toarcian (Early Jurassic) Posidonia Shale Formation is a possible unconventional gas source in Northern Europe and occurs within the Cleveland Basin (United Kingdom), the Anglo-Paris Basin (France), the Lower Saxony Basin and the Southwest Germany Basin (Germany), and the Roer Valley Graben, the

  3. A new sphenodontian (Lepidosauria: Rhynchocephalia) from the Late Triassic of Argentina and the early origin of the herbivore opisthodontians.

    Science.gov (United States)

    Martínez, Ricardo N; Apaldetti, Cecilia; Colombi, Carina E; Praderio, Angel; Fernandez, Eliana; Santi Malnis, Paula; Correa, Gustavo A; Abelin, Diego; Alcober, Oscar

    2013-12-07

    Sphenodontians were a successful group of rhynchocephalian reptiles that dominated the fossil record of Lepidosauria during the Triassic and Jurassic. Although evidence of extinction is seen at the end of the Laurasian Early Cretaceous, they appeared to remain numerically abundant in South America until the end of the period. Most of the known Late Cretaceous record in South America is composed of opisthodontians, the herbivorous branch of Sphenodontia, whose oldest members were until recently reported to be from the Kimmeridgian-Tithonian (Late Jurassic). Here, we report a new sphenodontian, Sphenotitan leyesi gen. et sp. nov., collected from the Upper Triassic Quebrada del Barro Formation of northwestern Argentina. Phylogenetic analysis identifies Sphenotitan as a basal member of Opisthodontia, extending the known record of opisthodontians and the origin of herbivory in this group by 50 Myr.

  4. Equatorial origin for Lower Jurassic radiolarian chert in the Franciscan Complex, San Rafael Mountains, southern California

    Science.gov (United States)

    Hagstrum, J.T.; Murchey, B.L.; Bogar, R.S.

    1996-01-01

    Lower Jurassic radiolarian chert sampled at two localities in the San Rafael Mountains of southern California (???20 km north of Santa Barbara) contains four components of remanent magnetization. Components A, B???, and B are inferred to represent uplift, Miocene volcanism, and subduction/accretion overprint magnetizations, respectively. The fourth component (C), isolated between 580?? and 680??C, shows a magnetic polarity stratigraphy and is interpreted as a primary magnetization acquired by the chert during, or soon after, deposition. Both sequences are late Pliensbachian to middle Toarcian in age, and an average paleolatitude calculated from all tilt-corrected C components is 1?? ?? 3?? north or south. This result is consistent with deposition of the cherts beneath the equatorial zone of high biologic productivity and is similar to initial paleolatitudes determined for chert blocks in northern California and Mexico. This result supports our model in which deep-water Franciscan-type cherts were deposited on the Farallon plate as it moved eastward beneath the equatorial productivity high, were accreted to the continental margin at low paleolatitudes, and were subsequently distributed northward by strike-slip faulting associated with movements of the Kula, Farallon, and Pacific plates. Upper Cretaceous turbidites of the Cachuma Formation were sampled at Agua Caliente Canyon to determine a constraining paleolatitude for accretion of the Jurassic chert sequences. These apparently unaltered rocks, however, were found to be completely overprinted by the A component of magnetization. Similar in situ directions and demagnetization behaviors observed in samples of other Upper Cretaceous turbidite sequences in southern and Baja California imply that these rocks might also give unreliable results.

  5. Sequence stratigraphy of the Kingak Shale (Jurassic-Lower Cretaceous), National Petroleum Reserve in Alaska

    Science.gov (United States)

    Houseknecht, D.W.; Bird, K.J.

    2004-01-01

    Beaufortian strata (Jurassic-Lower Cretaceous) in the National Petroleum Reserve in Alaska (NPRA) are a focus of exploration since the 1994 discovery of the nearby Alpine oil field (>400 MMBO). These strata include the Kingak Shale, a succession of depositional sequences influenced by rift opening of the Arctic Ocean Basin. Interpretation of sequence stratigraphy and depositional facies from a regional two-dimensional seismic grid and well data allows the definition of four sequence sets that each displays unique stratal geometries and thickness trends across NPRA. A Lower to Middle Jurassic sequence set includes numerous transgressive-regressive sequences that collectively built a clastic shelf in north-central NPRA. Along the south-facing, lobate shelf margin, condensed shales in transgressive systems tracts downlap and coalesce into a basinal condensed section that is likely an important hydrocarbon source rock. An Oxfordian-Kimmeridgian sequence set, deposited during pulses of uplift on the Barrow arch, includes multiple transgressive-regressive sequences that locally contain well-winnowed, shoreface sandstones at the base of transgressive systems tracts. These shoreface sandstones and overlying shales, deposited during maximum flooding, form stratigraphic traps that are the main objective of exploration in the Alpine play in NPRA. A Valanginian sequence set includes at least two transgressive-regressive sequences that display relatively distal characteristics, suggesting high relative sea level. An important exception is the presence of a basal transgressive systems tract that locally contains shoreface sandstones of reservoir quality. A Hauterivian sequence set includes two transgressive-regressive sequences that constitute a shelf-margin wedge developed as the result of tectonic uplift along the Barrow arch during rift opening of the Arctic Ocean Basin. This sequence set displays stratal geometries suggesting incision and synsedimentary collapse of the shelf

  6. ENVIRONMENTS AND FAUNAL PATTERNS IN THE KACHCHH RIFT BASIN, WESTERN INDIA, DURING THE JURASSIC

    Directory of Open Access Journals (Sweden)

    FRANZ THEODOR FÜRSICH

    2004-03-01

    Full Text Available Marine Jurassic sediments (Bajocian-Tithonian of the Kachchh Basin were deposited in a ramp setting. Except during the Middle and Late Bathonian, when a carbonate regime became established, the fill of the basin consists predominantly of siliciclastics. The sediments represent environments that range from coastal plains (rivers and associated flood plains with caliche nodules, deltas, brackish water lagoons, nearshore sand and iron-oolite bars of the inner ramp, generally situated above fair-weather wave-base, to the middle ramp influenced by storm-waves and by storm-generated currents, and finally to the outer ramp which is characterised by low energy, fine-grained sediments. Changes in relative sea level produced a cyclic sedimentation pattern. The rich benthic fauna of macroinvertebrates is dominated by bivalves, followed by brachiopods, gastropods, corals, serpulids, and sponges. The analysis of 370 statistical samples and more than 27, 000 specimens produced more than 40 benthic associations and assemblages. They show a relationship to several environmental parameters, two of which, salinity and climate, are briefly discussed. The spatial distribution of the facies and biota is outlined for two time slices, the Bathonian and the Callovian-Oxfordian, respectively.

  7. República Argentina

    OpenAIRE

    Centro de Estudios Sudamericanos (CENSUD)

    2008-01-01

    El sistema de gobierno en la Argentina adopta la forma representativa, republicana y federal (Constitución Nacional, art. 1º).Por su extensión -que corresponden al Continente Americano; al Continente Antártico (incluyendo las Islas Orcadas del Sur) y las islas australes (Georgias del Sur y Sandwich del Sur)- ocupa el cuarto lugar entre los países americanos (después de Canadá, Estados Unidos de América y la República Federativa del Brasil) y el séptimo a nivel mundial. Con una población de má...

  8. Tendencias preliminares en el registro arqueológico del curso medio y superior del arroyo El Lechuza, provincia de Santa Cruz, Argentina Preliminary trends in the archaeological record of the middle and upper courses of El Lechuza Arroyo, Santa Cruz province, Argentina

    Directory of Open Access Journals (Sweden)

    Nora Viviana Franco

    2007-12-01

    Full Text Available Se presentan aquí los resultados exploratorios de los trabajos realizados en el curso medio y superior del arroyo El Lechuza, localizado en el norte del río Santa Cruz (provincia de Santa Cruz. Se trata de un área con abundantes afloramientos volcánicos, con alturas entre ca. 550 y 870 msnm. Los resultados preliminares obtenidos apuntan hacia el aprovisionamiento local y explotación tanto de algunas materias primas líticas como de recursos faunísticos. Las evidencias procedentes del análisis de instrumentos líticos y óseos sugieren un cierto tiempo de estadía en el área, si bien no es posible precisar aún el carácter de estas ocupaciones humanas.This paper presents the preliminary results of surveys carried out around the middle and upper El Lechuza Arroyo. This area is located between ca. 550 and 870 m above-sea-level, with abundant volcanic outcrops. Lithic and faunal results point to local provisioning and processing of lithic and faunal resources. The results also suggest that hunter-gatherers remained in the area for some time, although we still do not know the nature of these occupations.

  9. Rock mechanics related to Jurassic underburden at Valdemar oil field

    DEFF Research Database (Denmark)

    Foged, Niels

    1999-01-01

    .It has been initiated as a feasibility study of the North Jens-1 core 12 taken in the top Jurassic clay shale as a test specimens for integrated petrological, mineralogical and rock mechanical studies. Following topics are studied:(1) Pore pressure generation due to conversion of organic matter...... and deformation properties of the clay shale using the actual core material or outcrop equivalents.(3) Flushing mechanisms for oil and gas from source rocks due to possibly very high pore water pressure creating unstable conditions in deeply burried sedimentsThere seems to be a need for integrating the knowledge...... in a number of geosciences to the benefit of common understanding of important reservoir mechanisms. Rock mechanics and geotechnical modelling might be key points for this understanding of reservoir geology and these may constitute a platform for future research in the maturing and migration from the Jurassic...

  10. A new carnivorous dinosaur from the Late Jurassic Solnhofen archipelago.

    Science.gov (United States)

    Göhlich, Ursula B; Chiappe, Luis M

    2006-03-16

    Small Late Jurassic theropod dinosaurs are rare worldwide. In Europe these carnivorous dinosaurs are represented primarily by only two skeletons of Compsognathus, neither of which is well preserved. Here we describe a small new theropod dinosaur from the Late Jurassic period of Schamhaupten in southern Germany. Being exquisitely preserved and complete from the snout to the distal third of the tail, the new fossil is the best-preserved predatory, non-avian dinosaur in Europe. It possesses a suite of characters that support its identification as a basal coelurosaur. A cladistic analysis indicates that the new taxon is closer to maniraptorans than to tyrannosauroids, grouping it with taxa often considered to be compsognathids. Large portions of integument are preserved along its tail. The absence of feathers or feather-like structures in a fossil phylogenetically nested within feathered theropods indicates that the evolution of these integumentary structures might be more complex than previously thought.

  11. A basal tyrannosauroid dinosaur from the Late Jurassic of China.

    Science.gov (United States)

    Xu, Xing; Clark, James M; Forster, Catherine A; Norell, Mark A; Erickson, Gregory M; Eberth, David A; Jia, Chengkai; Zhao, Qi

    2006-02-01

    The tyrannosauroid fossil record is mainly restricted to Cretaceous sediments of Laurasia, although some very fragmentary Jurassic specimens have been referred to this group. Here we report a new basal tyrannosauroid, Guanlong wucaii gen. et sp. nov., from the lower Upper Jurassic of the Junggar Basin, northwestern China. G. wucaii is the oldest known tyrannosauroid and shows several unexpectedly primitive pelvic features. Nevertheless, the limbs of G. wucaii share several features with derived coelurosaurs, and it possesses features shared by other coelurosaurian clades. This unusual combination of character states provides an insight into the poorly known early radiation of the Coelurosauria. Notably, the presumed predatory Guanlong has a large, fragile and highly pneumatic cranial crest that is among the most elaborate known in any non-avian dinosaur and could be comparable to some classical exaggerated ornamental traits among vertebrates.

  12. The palaeogeography of Sundaland and Wallacea since the Late Jurassic

    OpenAIRE

    Robert Hall

    2013-01-01

    The continental core of Southeast (SE) Asia, Sundaland, was assembled from Gondwana fragments by the Early Mesozoic. Continental blocks rifted from Australia in the Jurassic [South West (SW) Borneo, East Java-West Sulawesi-Sumba], and the Woyla intraoceanic arc of Sumatra, were added to Sundaland in the Cretaceous. These fragments probably included emergent areas and could have carried a terrestrial flora and fauna. Sarawak, the offshore Luconia-Dangerous Grounds areas, and Palawan include As...

  13. Hedeoma mandonianum (Lamiaceae en Argentina Hedeoma mandonianum (Lamiaceae in Argentina

    Directory of Open Access Journals (Sweden)

    Alberto Carlos Slanis

    2005-12-01

    Full Text Available En el presente trabajo se confirma la presencia de H. mandonianum Wedd. en el Noroeste de Argentina, la cual había sido citada previamente para los Andes de Perú y Bolivia. Se presenta una clave para diferenciar las especies argentinas de Hedeoma como así también descripción, ilustraciones, usos, distribución geográfica y observaciones ecológicas de la especie aquí tratada.In this paper the presence of H. mandonianum Wedd. from Northwestern Argentina is confirmed. This species has been previously cited for the Andes of Peru and Bolivia. A description, illustrations, uses, geographical distribution and ecological observations of the treated species are presented herein, together a key to identify the species of the genus Hedeoma in Argentina.

  14. Earliest Marine beds in the Jurassic sedimentary record near the Huajuapan-Petlalcingo region, southern Mexico and their paleogeographic implications

    Science.gov (United States)

    Contla, D.

    2008-12-01

    A paleogeographic model of Jurassic-Cretaceous is presented, the study area is the region near Huajuapan de Leon in the Mixteca Terrane, Mexico where a sedimentary successions constituted by interlayered terrestrial and marine beds, provides evidence of transgression and regression episodes. The sediments in the study zone were deposited over a Paleozoic metamorphic basement, the Acatlan Complex. The stratigraphic features in the Middle Jurassic of the terrestrial beds indicate a depositional elements varying from alluvial fans to floodplains and channel deposits, represented by conglomerates, sandy conglomerates and sandstones. After, in the same epoch (Bajocian and Bathonian age) a transgression coming from the Pacific Ocean covered the region. A transitional zone between continental and marine sediments is situated between Tezoatlan and Petlalcingo, the actual cross section consists in the earliest marine beds: limestones interlayered with terrestrial beds. Fossil contents in this beds indicate an age between the Oxfordian and the Tithonian. During this period of transgression the paleogeography was dominated by a small bay with shallow waters connected in the south with the Pacific Ocean, represented principally by limestone and dolomite units. At the end of the transgression, volcanic episodes occurred and the land emerged again. The sedimentary beds were later affected by tectonic activity that produced a normal fault near Zapotitlan, putting the metamorphic basement in contact with the sedimentary sequence.

  15. JURASSIC PALAEOGEOGRAPHY OF THE TRANSDANUBIAN CENTRAL RANGE (HUNGARY

    Directory of Open Access Journals (Sweden)

    ATTILA VÖRÖS

    1998-03-01

    Full Text Available The Transdanubian Central Range (TCR is a flattened range of hills in northern Transdanubia (Hungary, formed mainly by Mesozoic carbonate rocks showing strong facies similarities with the Southern Alps and the Austroalpine domain. The Jurassic system is divided into several formations of predominantly pelagic limestones. Ammonoids are frequent and were collected bed-by-bed in numerous sections, providing an excellent biostratigraphic resolution. The thickness of the Jurassic system is usually small but changes along the strike of the TCR. It reaches a maximum thickness of 500 m in the western part; is very variable (10-400 m in the central segment (Bakony Mts. and rather low (less than 100 m in the east (Gerecse. In the Bakony segment, the thickness variation reflects the strongly dissected topography of the Jurassic sea-floor. Synsedimentary tectonics is dominated by normal faults; tilted blocks and listric faults may be inferred only in the east.Five main steps were identified in the palaeogeographic evolution: 1 Late Hettangian: carbonate oolitic shoals prevail, except for a few sites where non-deposition or neritic sediments occur. 2 Sinemurian and Pliensbachian: tectonic disintegration resulted in an intricate pattern of submarine horsts and intervening basins, with condensed sedimentation or non-deposition on the horsts and thicker, continuous sedimentary sequences in the basins. The submarine topographic highs are surrounded by aprons of redeposited material (scarp breccias, brachiopod coquinas, crinoidal calcarenites, spiculitic cherty limestones, while pure or argillaceous limestones (Rosso Ammonitico prevail in the distal areas. 3 Early Toarcian: the Tethys-wide anoxic event is superimposed on the previous submarine bottom topography; the resulting black shales and sedimentary Mn-ores are concentrated on the western sides of some horsts. 4 Dogger to Early Malm: radiolarites with heterochronous lower and upper boundaries (Aalenian to

  16. Argentina: Nationality, Demography and Security

    Science.gov (United States)

    1993-04-22

    The Western Border It extends along the Andes ridge from the North of Argentina’s Catamarca Province to the intersection of the Beagle Channel with the...And the Chilean workers are not powerless. For example, during the Chilean-Argentine clash over the Beagle Channel (1980), coal production almost...and others. "Probiemas Argentinosy sus Soluciones", Ed. Pleamar, Buenos Aires, 1976. 3. Levene, H. " Historia Argentina", Ed. Pleamar, Buenos Aires

  17. Metropolization in Argentina

    OpenAIRE

    Dagnino Pastore, José María; Canavese, Paula

    1996-01-01

    A partir de la regla de "orden-magnitud" el trabajo formula el concepto de "metropolización" (Smger) y explicita su relación con el índice de urbanización usual. Rastrea la evolución de la metropolización en Argentina a través de sus ocho censos, tanto para el conjunto de todos los centros urbanos como para tres subconjuntos: grandes, medianos y pequeños. El trabajo presenta después la idea de economías de "concentración geográfica" de las actividades (Lösch), explorando su relación -bajo sup...

  18. Argentina, ¿trabaja?

    OpenAIRE

    De Sena, Angélica; Chahbenderian, Florencia

    2012-01-01

    En la última década en la Argentina se implementaron una serie de políticas sociales denominadas socio-productivas, socio-laboral y socio-económicas con el objeto de mejorar la situación de desempleo o precariedad laboral de la población. Las mismas pueden considerarse un modo de compensación de los efectos de exclusión del régimen de producción y acumulación vigente. En este contexto en el año 2009 nace el Plan “Ingreso Social con Trabajo” desde el Ministerio de Desarrollo Social, que declar...

  19. gobierno dividido en Argentina

    Directory of Open Access Journals (Sweden)

    María Elisa Alonso García

    2008-01-01

    Full Text Available Este artículo es una reflexión sobre el gobierno dividido en Argentina, y un análisis sobre las consecuencias negativas que tiene el binomio presidencialismo –multipartidismo para la gobernabilidad y el desarrollo institucional del país. El estudio del caso argentino permite comprobar que el gobierno en minoría no constituye un obstáculo para el desarrollo institucional, y que los problemas que de él se derivan, como el bloqueo legislativo y el conflicto institucional pueden solventarse, evitando la crisis. En este sentido, se analiza el papel jugado por los partidos provinciales, que han sido determinantes para evitar los problemas vinculados con el gobierno dividido

  20. DERECHO AMBIENTAL EN ARGENTINA

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    Silvia Nonna

    2014-05-01

    Full Text Available El objetivo de la presente publicación es brindar un panorama general, introductorio y actualizado del derecho ambiental argentino. Entendiendo que el derecho ambiental es un signo de nuestra era y que por la dinamicidad de la cuestión ambiental requiere de permanente actualización regulatoria. La autora desarrolla en forma objetiva su postura en relación con la necesidad de hacer sostenible al derecho ambiental. Para luego analizar brevemente la situación actual del derecho vigente en Argentina, haciendo un rápido y resumido recorrido desde la última reforma de la Constitución Nacional hasta la consideración especial de cada una de las nuevas normas de presupuestos mínimos de protección ambiental.

  1. Soft rocks in Argentina

    Institute of Scientific and Technical Information of China (English)

    Giambastiani; Mauricio

    2014-01-01

    Soft rocks are a still fairly unexplored chapter in rock mechanics. Within this category are the clastic sedimentary rocks and pyroclastic volcanic rocks, of low to moderate lithification (consolidation, cemen-tation, new formed minerals), chemical sedimentary rocks and metamorphic rocks formed by minerals with Mohs hardness less than 3.5, such as limestone, gypsum, halite, sylvite, between the first and phyllites, graphitic schist, chloritic shale, talc, etc., among the latter. They also include any type of rock that suffered alteration processes (hydrothermal or weathering). In Argentina the study of low-strength rocks has not received much attention despite having extensive outcrops in the Andes and great impact in the design criteria. Correlation between geomechanical properties (UCS, deformability) to physical index (porosity, density, etc.) has shown promising results to be better studied. There are many studies and engineering projects in Argentina in soft rock geological environments, some cited in the text (Chihuído dam, N. Kirchner dam, J. Cepernic Dam, etc.) and others such as International Tunnel in the Province of Mendoza (Corredor Bioceánico), which will require the valuable contribution from rock mechanics. The lack of consistency between some of the physical and mechanical parameters explored from studies in the country may be due to an insufficient amount of information and/or non-standardization of criteria for testing materials. It is understood that more and better academic and professional efforts in improv-ing techniques will result in benefits to the better understanding of the geomechanics of weak rocks.

  2. New discovery of fossil cycad-like plants from the Middle Jurassic of West Liaoning, China

    Institute of Scientific and Technical Information of China (English)

    WANG Yongdong; ZHANG Wu; ZHENG Shaolin; SAIKI Keni'chi; LI Nan

    2005-01-01

    @@ The Cycadales are one of the most ancient lineages ofseed plants, with a fossil record that extends over 250 mil-lion years. Cycads are believed to have originated fromthe Late Palaeozoic, and reached its maximum diversityand distribution during the Mesozoic; however, their evo-lutionary history has remained relatively poorly under-stood[1―4].

  3. Isolated theropod teeth from the Middle Jurassic of Niger and the early dental evolution of Spinosauridae

    Directory of Open Access Journals (Sweden)

    Alejandro Serrano-Martínez

    2016-06-01

    Full Text Available Four isolated theropod teeth from the ?Bathonian “Argiles de l’Irhazer” in Niger are described. The teeth were found in association with the holotype of the basal sauropod Spinophorosaurus nigerensis. These specimens have been assigned to two different taxa by independent analyses, such as direct comparison with teeth previously described in the literature, discriminant and morphometric analyses from metric characters, and cladistic and cluster analyses from discrete characters. The results suggest that three teeth share affinities with those of Megalosauridae and Allosauridae, belonging most likely to the former. The fourth tooth might be from a member of the stem group Spinosauridae. If so, this would be the oldest representative of this clade. This tooth shows a combination of characters that are unusual in typical spinosaurid teeth (crown moderately compressed labiolingually and curved distally with minute denticles on the carina and a deeply veined enamel surface texture without apicobasal ridges. This could shed light on the morphological transition from the plesiomorphic ziphodont dental pattern to that of Spinosauridae. This tooth would also allow a better understanding of the origin of the spinosaurids, supporting a Gondwanan origin for the group.

  4. Composition of sandstone and heavy minerals implies the provenance of Kuqa Depression in Jurassic, Tarim basin, China

    Institute of Scientific and Technical Information of China (English)

    WU Chaodong; LIN Changsong; SHEN Yanping; FENG Xue

    2005-01-01

    The petrological characteristics and heavy mineral assembly of the Jurassic System in Kuqa Basin are consistent with the tectonic evolution, which is the major factor controlling the filling process of Kuqa Basin. Controlled by the source areas at the both sides of the Basin, the matrixes are dominated by sedimentary rock, high-grade metamorphic rock, acid magmatic rock, and the highest heavy mineral assemblage of zircon-garnet-magnetite in the content. According to heavy mineral indexes, the Jurassic strata can be classified into three rhythmic units of heavy mineral. The lower sequence contains abundant heavy minerals and relatively high content of detritus and its matrixes primarily came form the recycling orogen. The assemblage of "zircon-garnet-magnetite" indicates that the sedimentary area in the early evolution period of the basin is relatively near the provenance. The middle sequence is different from the lower sequence in the heavy mineral assemblage and has the different characteristics from that of source rock. The heavy mineral assemblage is "garnet-zircon" with the highest content of garnet and its main matrices are the high-grade metamorphic rock, acid magmatic rock and hydrothermal vein at the northeastern edge of the basin. The middle and upper sequences are characterized by the clast provenance, which is primarily from the recycling orogen at the northern edge of the basin and secondarily from the southern uplift. As a result of the two provenances, the strata with apparent changes of heavy mineral assemblage and index better coincides with the interfaces of the secondary strata sequences, which reflects the denudation history and the filling process of the orogen at the northern edge of the basin.

  5. A new primitive Neornithischian dinosaur from the Jurassic of Patagonia with gut contents

    Science.gov (United States)

    Salgado, Leonardo; Canudo, José I.; Garrido, Alberto C.; Moreno-Azanza, Miguel; Martínez, Leandro C. A.; Coria, Rodolfo A.; Gasca, José M.

    2017-01-01

    We describe a new species of an ornithischian dinosaur, Isaberrysaura mollensis gen. et sp. nov. The specimen, consisting in an almost complete skull and incomplete postcranium was collected from the marine-deltaic deposits of the Los Molles Formation (Toarcian-Bajocian), being the first reported dinosaur for this unit, one of the oldest from Neuquén Basin, and the first neornithischian dinosaur known from the Jurassic of South America. Despite showing a general stegosaurian appearance, the extensive phylogenetic analysis carried out depicts Isaberrysaura mollensis gen. et sp. nov. as a basal ornithopod, suggesting that both Thyreophora and neornithischians could have achieved significant convergent features. The specimen was preserved articulated and with some of its gut content place in the middle-posterior part of the thoracic cavity. Such stomach content was identified as seeds, most of them belonging to the Cycadales group. This finding reveals a possible and unexpected role of this ornithischian species as seed-dispersal agent. PMID:28202910

  6. A bizarre Jurassic maniraptoran theropod with preserved evidence of membranous wings.

    Science.gov (United States)

    Xu, Xing; Zheng, Xiaoting; Sullivan, Corwin; Wang, Xiaoli; Xing, Lida; Wang, Yan; Zhang, Xiaomei; O'Connor, Jingmai K; Zhang, Fucheng; Pan, Yanhong

    2015-05-01

    The wings of birds and their closest theropod relatives share a uniform fundamental architecture, with pinnate flight feathers as the key component. Here we report a new scansoriopterygid theropod, Yi qi gen. et sp. nov., based on a new specimen from the Middle-Upper Jurassic period Tiaojishan Formation of Hebei Province, China. Yi is nested phylogenetically among winged theropods but has large stiff filamentous feathers of an unusual type on both the forelimb and hindlimb. However, the filamentous feathers of Yi resemble pinnate feathers in bearing morphologically diverse melanosomes. Most surprisingly, Yi has a long rod-like bone extending from each wrist, and patches of membranous tissue preserved between the rod-like bones and the manual digits. Analogous features are unknown in any dinosaur but occur in various flying and gliding tetrapods, suggesting the intriguing possibility that Yi had membranous aerodynamic surfaces totally different from the archetypal feathered wings of birds and their closest relatives. Documentation of the unique forelimbs of Yi greatly increases the morphological disparity known to exist among dinosaurs, and highlights the extraordinary breadth and richness of the evolutionary experimentation that took place close to the origin of birds.

  7. Latest Jurassic-early Cretaceous regressive facies, northeast Africa craton

    Energy Technology Data Exchange (ETDEWEB)

    van Houten, F.B.

    1980-06-01

    Nonmarine to paralic detrital deposits accumulated in six large basins between Algeria and the Arabo-Nubian shield during major regression in latest Jurassic and Early Cretaceous time. The Ghadames Sirte (north-central Libya), and Northern (Egypt) basins lay along the cratonic margin of northeastern Africa. The Murzuk, Kufra, and Southern (Egypt) basins lay in the south within the craton. Data for reconstructing distribution, facies, and thickness of relevant sequences are adequate for the three northern basins only. High detrital influx near the end of Jurassic time and in mid-Cretaceous time produced regressive nubian facies composed largely of low-sinuosity stream and fahdelta deposits. In the west and southwest the Ghadames, Murzuk, and Kufra basins were filled with a few hundred meters of detritus after long-continued earlier Mesozoic aggradation. In northern Egypt the regressive sequence succeeded earlier Mesozoic marine sedimentation; in the Sirte and Southern basins correlative deposits accumulated on Precambrian and Variscan terranes after earlier Mesozoic uplift and erosion. Waning of detrital influx into southern Tunisia and adjacent Libya in the west and into Israel in the east initiated an Albian to early Cenomanian transgression of Tethys. By late Cenomanian time it had flooded the entire cratonic margin, and spread southward into the Murzuk and Southern basins, as well as onto the Arabo-Nubian shield. Latest Jurassic-earliest Cretaceous, mid-Cretaceous, and Late Cretaceous transgressions across northeastern Africa recorded in these sequences may reflect worldwide eustatic sea-level rises. In contrast, renewed large supply of detritus during each regression and a comparable subsidence history of intracratonic and marginal basins imply regional tectonic control. 6 figures.

  8. Coccocypselum pulchellum (Rubiaceae, nuevo registro para Argentina

    Directory of Open Access Journals (Sweden)

    Elsa L. Cabral

    2007-01-01

    Full Text Available Se cita Coccocypselum pulchellum por primera vez para Argentina, en Predio Guaraní, Misiones. Esta es la tercera especie de Coccocypselum registrada para la flora de Argentina junto con C. hasslerianum y C. lanceolatum. Se incluyen descripciones, ilustraciones y una clave para reconocer las tres especies argentinas de Coccocypselum.

  9. Newly discovered Jurassic skarnfields in the Ecuadorian Andes

    Science.gov (United States)

    Litherland, M.; Fortey, N. J.; Beddoe-Stephens, B.

    1992-08-01

    A series of calcic magnetite skarn klippen in the north of the Cordillera Real are interpreted as erosional relics of a great skarn sheet, over 150 km long, formed by thrusting of island-arc type sediments and volcanics over the Jurassic Azafran batholith during an accretion event. The skarns are contrasted petrographically and compositionally with those of the Nambija field in the south of the Cordillera, which probably relates to the same chain of batholiths. However, the Nambija skarns are autochthonous and rich in gold, with Au:Ag ratios in the region of 20:1, whereas those to the north are allochthonous and relatively barren.

  10. First records of crocodyle and pterosaur tracks in the Upper Jurassic of Portugal

    DEFF Research Database (Denmark)

    Mateus, Octavio; Milàn, Jesper

    2010-01-01

    The Upper Jurassic of Portugal has a rich vertebrate fauna well documented from both body and trace fossils. Although the occurrence of crocodyles and pterosaurs is well documented from body fossils, trace fossils from both groups were unknown until now. Here we describe an isolated crocodyle...... Late Jurassic vertebrate fauna of Portugal....

  11. The Tendaguru Formation (Late Jurassic to Early Cretaceous, southern Tanzania: definition, palaeoenvironments, and sequence stratigraphy

    Directory of Open Access Journals (Sweden)

    R. Bussert

    2009-08-01

    Full Text Available The well-known Late Jurassic to Early Cretaceous Tendaguru Beds of southern Tanzania have yielded fossil plant remains, invertebrates and vertebrates, notably dinosaurs, of exceptional scientific importance. Based on data of the German-Tanzanian Tendaguru Expedition 2000 and previous studies, and in accordance with the international stratigraphic guide, we raise the Tendaguru Beds to formational rank and recognise six members (from bottom to top: Lower Dinosaur Member, Nerinella Member, Middle Dinosaur Member, Indotrigonia africana Member, Upper Dinosaur Member, and Rutitrigonia bornhardti-schwarzi Member. We characterise and discuss each member in detail in terms of derivation of name, definition of a type section, distribution, thickness, lithofacies, boundaries, palaeontology, and age. The age of the whole formation apparently ranges at least from the middle Oxfordian to the Valanginian through Hauterivian or possibly Aptian. The Tendaguru Formation constitutes a cyclic sedimentary succession, consisting of three marginal marine, sandstone-dominated depositional units and three predominantly coastal to tidal plain, fine-grained depositional units with dinosaur remains. It represents four third-order sequences, which are composed of transgressive and highstand systems tracts. Sequence boundaries are represented by transgressive ravinement surfaces and maximum flooding surfaces. In a more simple way, the depositional sequences can be subdivided into transgressive and regressive sequences/systems tracts. Whereas the transgressive systems tracts are mainly represented by shallow marine shoreface, tidal channel and sand bar sandstones, the regressive systems tracts predominantly consist of shallow tidal channel, tidal flat, and marginal lagoonal to supratidal deposits. doi:10.1002/mmng.200900004

  12. del Estero, Argentina

    Directory of Open Access Journals (Sweden)

    Josefa Delgado

    2007-01-01

    Full Text Available Esta investigación, desde una perspectiva holística, buscó conocer en las familias de niños que asisten a los comedores comunitarios en un barrio capitalino de Santiago del Estero, Argentina, la red de apoyo que utilizan y los recursos que obtienen para poder resolver sus necesidades cotidianas. Es un estudio cuanticualitativo. Los datos fueron recolectados por encuestas parcialmente estructuradas y entrevistas en profundidad. El análisis de los datos se basó en identificación de frecuencias absolutas y relativas. Para los datos cualitativos se usó el referencial fenomenológico heideggeriano. Los resultados indican que 48% de las familias tienen 4 a 5 elementos en la red de apoyo; 91% buscan alimentos, 84% salud y el 73% trabajo; esta reducida red les genera importantes dificultades al momento de satisfacer sus necesidades básicas. La falta de trabajo y baja escolaridad son los principales condicionantes de su aislamiento social.

  13. Esperando otro 17 de Octubre: la identidad de clase media y la experiencia de la crisis de 2001 en Argentina

    Directory of Open Access Journals (Sweden)

    Ezequiel Adamovsky

    2012-11-01

    Full Text Available This article seeks to contribute to a better understanding of the political dimension to middle-class identity in Argentina, by analyzing an image that appeared after 2001: that of a “17th October of the Middle Class”. This curious image, and the shifts in its meanings from its first introduction to its most recent manifestations, is interpreted by locating it into two different contexts. On one hand, the socio-economic, political and identity changes that Argentine society experienced during and after the 1990s. On the other hand, the longer context of the trauma that the emergence of Peronism produced in 1945, which still casts effects on Argentina culture. The image of the “17th October of the Middle Class” in thus interpreted as a fantasy of closing the Peronist political horizon, by replicating the event that opened it in 1945, this time with the middle (and not the working class in the leading role

  14. Precious metaltellurides and other Te-bearing minerals in different paragenesis of Argentina: A review

    Directory of Open Access Journals (Sweden)

    Milka K de Brodtkorb

    2009-06-01

    Full Text Available Severalpolymetallic deposits containing tellurides and Te-bearing minerals occur indifferent geologic terrains of Argentina. Tellurides with Ag and /or Au arewidespread in meso and epithermal environments; they are structurallycontrolled and genetically related to Jurassic or Miocene-Pliocene volcanism.These species are represented by calaverite, hessite, stützite, krennerite,sylvanite, petzite and cervellite. Other Te-bearing minerals are present notonly in epithermal deposits but also in different assemblages such asintraplutonic W deposits, skarn and mafic-ultramafic bodies. They are Te,altaite, nagyágite, melonite- merenskyite, tetradymite, telurobismuthite,kawazulite, Te-canfieldite and goldfieldite. Paragenesis of the differentdeposits and chemical data of the minerals are given.

  15. Hungry China Shops in Argentina

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    @@ Chinese investment is flooding into Argentina as the Asian giant expands its global commodity hunt from the raw materials used in industry to the foodstuffs needed to feed its 1.3 billion citizens. China's investment in Latin America hit USI15.6 billion during the 12-month period through the end of May, nearly three times greater than the year-ago period, consulting firm Deloitte said in a report.Of that amount, Brazil received about 60% and Argentina close to 40%.

  16. Tick paralysis cases in Argentina

    Directory of Open Access Journals (Sweden)

    Carlos Remondegui

    2012-08-01

    Full Text Available Tick paralysis (TP occurs worldwide and is caused by a neurotoxin secreted by engorged female ticks that affects the peripheral and central nervous system. The clinical manifestations range from mild or nonspecific symptoms to manifestations similar to Guillain-Barré syndrome, bulbar involvement, and death in 10% of the patients. The diagnosis of TP is clinical. To our knowledge, there are no formal reports of TP in humans in South America, although clusters of TP among hunting dogs in Argentina have been identified recently. In this paper, clinical features of two cases of TP occurring during 1994 in Jujuy Province, Argentina, are described.

  17. Jurassic tetrapods and flora of Cañadón Asfalto Formation in Cerro Cóndor area, Chubut Province

    Directory of Open Access Journals (Sweden)

    Ignacio H. Escapa

    2008-12-01

    Full Text Available The plant and tetrapod fossil record of the Cañadón Asfalto Formation (Middle to Late Jurassic found in Cerro Cóndor area (Chubut Province is summarized here. The flora is dominated by conifers (Araucariaceae, Cupressaceae sensu lato but also includes ferns and equisetaleans. The tetrapod fauna is composed of dinosaur taxa described in the 70's as well as other remains recently described and other vertebrate groups such as amphibians, turtles, and mammals. The amphibian remains have been interpreted as representatives of a new species of Notobatrachus, considered one of the most basal members of the anuran lineage. Similarly, turtle remains have been recently recognized as a new species of basal turtle, bringing valuable information about the early evolution of this group. The dinosaur remains are largely dominated by saurischian taxa, represented by basal forms of Eusauropoda and Tetanurae. In addition, three different mammalian species have been identified and considered as early representatives of an endemic Gondwanan mammalian fauna. The fossil record of this formation represents the most completely known biota from the continental Middle to Late Jurassic of the Southern Hemisphere and one of the most complete of the entire world.

  18. Reconstruction of the Upper Jurassic Morrison Formation extinct ecosystem—a synthesis

    Science.gov (United States)

    Turner, Christine E.; Peterson, Fred

    2004-05-01

    A synthesis of recent and previous studies of the Morrison Formation and related beds, in the context of a conceptual climatic/hydrologic framework, permits reconstruction of the Late Jurassic dinosaurian ecosystem throughout the Western Interior of the United States and Canada. Climate models and geologic evidence indicate that a dry climate persisted in the Western Interior during the Late Jurassic. Early and Middle Kimmeridgian eolian deposits and Late Kimmeridgian alkaline, saline wetland/lacustrine deposits demonstrate that dryness persisted throughout the Kimmeridgian. Tithonian-age coal reflects lower evaporation rates associated with a slight cooling trend, but not a significant climate change. With a subtropical high over the Paleo-Pacific Ocean and atmospheric circulation generally toward the east, moisture carried by prevailing winds "rained out" progressively eastward, leaving the continental interior—and the Morrison depositional basin—dry. Within the basin, high evaporation rates associated with the southerly paleolatitude and greenhouse effects added to the dryness. Consequently, the two main sources of water—groundwater and surface water—originated outside the basin, through recharge of regional aquifers and streams that originated in the western uplands. Precipitation that fell west of the basin recharged aquifers that underlay the basin and discharged in wetlands and lakes in the distal, low-lying part of the basin. Precipitation west of the basin also fed intermittent and scarce perennial streams that flowed eastward. The streams were probably "losing" streams in their upstream reaches, and contributed to a locally raised water table. Elsewhere in the basin, where the floodplain intersected the water table, small lakes dotted the landscape. Seasonal storms, perhaps in part from the Paleo-Gulf of Mexico, brought some precipitation directly to the basin, although it was also subjected to "rain out" en route. Thus, meteoric input to the

  19. Coal petrology and genesis of Jurassic coal in the Ordos Basin, China

    Directory of Open Access Journals (Sweden)

    Weihua Ao

    2012-01-01

    Full Text Available Multiple sets of thick coal beds characterized by simple structure and shallow burial depth were developed in the Early and Middle Jurassic strata of the Ordos Basin, northwestern China. The huge reserves of this high quality coal have a high commercial value. We studied the coal’s petrologic characteristics and its maceral distribution to determine the maceral’s contribution to generation of oil and gas. The results show that the Jurassic coals in the Ordos Basin have special petrological features because of the Basin’s unique depositional environment which was mainly a series of high-stand swamps in the upper fluvial system. These petrographic features are a result of the development of typical inland lakes where some sand bodies were formed by migrating rivers. After burial, the peat continued to undergo oxidizing conditions, this process generated extensive higher inertinite contents in the coals and the vitrinite components were altered to semi-vitrinite. The macroscopic petrographic types of these Jurassic coals are mainly semi-dull coal, dull coal, semilustrous and lustrous coal. The proportions of semi-dull coal and dull coal are higher in the basin margins, especially in the area near the northern margin. The numbers of semilustrous and lustrous coals increase southwards and towards the central basin. This situation indicates that different coal-forming swamp environments have major controlling effects on the coal components. Another observation is that in the Ordos’ coal sequences, especially in the lower part, some sandstone beds are thick, up to 20 m with a coarse grain size. The higher fusinite content in the macerals accompanies a higher semi-vitrinite content with more complete and regular plant cell structure. The fusinite structure is clear and well preserved. After burial, the lithology of the roof and floor rocks can continue to affect the evolution of coal petrology. The sand bodies in the roof and floor exhibit good

  20. Reconstruction of the Upper Jurassic Morrison Formation extinct ecosystem - A synthesis

    Science.gov (United States)

    Turner, C.E.; Peterson, F.

    2004-01-01

    A synthesis of recent and previous studies of the Morrison Formation and related beds, in the context of a conceptual climatic/hydrologic framework, permits reconstruction of the Late Jurassic dinosaurian ecosystem throughout the Western Interior of the United States and Canada. Climate models and geologic evidence indicate that a dry climate persisted in the Western Interior during the Late Jurassic. Early and Middle Kimmeridgian eolian deposits and Late Kimmeridgian alkaline, saline wetland/lacustrine deposits demonstrate that dryness persisted throughout the Kimmeridgian. Tithonian-age coal reflects lower evaporation rates associated with a slight cooling trend, but not a significant climate change. With a subtropical high over the Paleo-Pacific Ocean and atmospheric circulation generally toward the east, moisture carried by prevailing winds "rained out" progressively eastward, leaving the continental interior-and the Morrison depositional basin-dry. Within the basin, high evaporation rates associated with the southerly paleolatitude and greenhouse effects added to the dryness. Consequently, the two main sources of water-groundwater and surface water-originated outside the basin, through recharge of regional aquifers and streams that originated in the western uplands. Precipitation that fell west of the basin recharged aquifers that underlay the basin and discharged in wetlands and lakes in the distal, low-lying part of the basin. Precipitation west of the basin also fed intermittent and scarce perennial streams that flowed eastward. The streams were probably "losing" streams in their upstream reaches, and contributed to a locally raised water table. Elsewhere in the basin, where the floodplain intersected the water table, small lakes dotted the landscape. Seasonal storms, perhaps in part from the Paleo-Gulf of Mexico, brought some precipitation directly to the basin, although it was also subjected to "rain out" en route. Thus, meteoric input to the basin was

  1. Tandil, Buenos Aires, Argentina

    Directory of Open Access Journals (Sweden)

    María L. Bakker

    2006-01-01

    Full Text Available Se coleccionaron hojas maduras de ejemplares adultos de Populus alba, Populus deltoides, Robinia pseudoacacia, Ulmus pumila y Fraxinus americana del Campus Universitario, Tandil, Buenos Aires, Argentina (37° 19’S, 59° 08’O en febrero de 2004. La cera cuticular fue extraída, purificada, y el contenido y proporción relativa de n-alcanos de número impar de carbonos (C23C35 fue cuantificado mediante cromatografía gas-líquido capilar. La concentración total de n-alcanos (mg/kg MS fue P. alba (6935 > Robinia (1571 > P. deltoides (1379 > Ulmus (880 > Fraxinus (467. Los n-alcanos más abundantes en todas las especies fueron C27 y C29 que constituyeron entre 10 y 51% y entre 35 y 76% del total respectivamente, excepto en Fraxinus donde los más abundantes fueron C29 y C31 que constituyeron el 31 y 49% del total respectivamente. P. alba y P. deltoides difirieron no solo en la concentración total de n-alcanos sino también en la proporción relativa de C27 y C29, siendo C29 el n-alcano más abundante en la segunda especie (76% igual que en Robinia (75%. La presencia de nalcanos de número par de carbonos no fue detectable o resultó muy baja en general en todas las especies, con excepción de C26, C28 y C30, este último se destacó particularmente en Fraxinus.

  2. Sessea regnellii (Solanaceae en Argentina

    Directory of Open Access Journals (Sweden)

    Héctor A. Keller

    2006-01-01

    Full Text Available Se cita por primera vez a Sessea regnelli para la flora argentina. Se presenta una descripción de la especie sobre la base de los ejemplares examinados, como así también ilustraciones y observaciones ecológicas.

  3. NREL technical assistance to Argentina

    Energy Technology Data Exchange (ETDEWEB)

    Lilienthal, P. [National Renewable Energy Lab., Golden, CO (United States)

    1997-12-01

    This paper describes assistance to Argentina from the National Renewable Energy Laboratory which has touched on four programs: tariff analysis for rural concessions programs; wind/diesel hybrid retrofits in Patagonia; small hybrid systems designs for rural schools; an assessment of wind resources. The paper expands briefly on the first two points.

  4. Early Jurassic Flora and Stratigraphy from Shansonggang of Southern Jilin,China

    Institute of Scientific and Technical Information of China (English)

    Fengxiang Liu; Yuewu Sun; Chunlin Sun; Jiansheng Lu; Yanhua Zhao

    2003-01-01

    More than 35 species belonging to 22 genera of fossil plants are recognized by the authors from the Shansonggang flora in the 8hansonggang Basin of Jilin, China. Among them, the coexistence of Coniopteris and Cycadocarpidium demonstrates that the present flora possesses the characters of the early assemblage of Early Jurassic floras in Eurasia. Therefore, the age of the Shansonggang flora is considered the Early Jurassic.This study would be beneficial for better understanding the paleoecological and paleoclimatic characteristics of the Shansonggang Basin. Based mainly on the characters of the flora, the authors suggest that the Lower Jurassic coal-bearing strata, the Shansongang Formation, should namely be renewed.

  5. An Undercover Angiosperm from the Jurassic of China

    Institute of Scientific and Technical Information of China (English)

    ZHENG Shaolin; WANG Xin

    2010-01-01

    Searching for early angiosperms is a riveting activity in botany because it helps to resolve the phylogenetic relationships among seed plants and among angiosperms themselves.One of the challenges for this job is what the target fossils look like.Most possibly early angiosperms may elude our scrutiny with gymnospermous appearances.This possibility becomes a reality in a Jurassic plant,Solaranthus gen.nov,which bears a peltaspermalean appearance and enclosed ovules.According to knowledge available hitherto,the latter feature makes it an angiosperm.However,such a feature is more likely to be eclipsed by its gymnospermous appearance.The early age and unexpected character assemblage of Solaranthus urge for a fresh look on the assumed-simple relationship between angiosperms and gymnosperms.Its resemblance to the order Peltaspermales favors the Mostly Male Theory.

  6. Extreme adaptations for aquatic ectoparasitism in a Jurassic fly larva.

    Science.gov (United States)

    Chen, Jun; Wang, Bo; Engel, Michael S; Wappler, Torsten; Jarzembowski, Edmund A; Zhang, Haichun; Wang, Xiaoli; Zheng, Xiaoting; Rust, Jes

    2014-06-24

    The reconstruction of ancient insect ectoparasitism is challenging, mostly because of the extreme scarcity of fossils with obvious ectoparasitic features such as sucking-piercing mouthparts and specialized attachment organs. Here we describe a bizarre fly larva (Diptera), Qiyia jurassica gen. et sp. nov., from the Jurassic of China, that represents a stem group of the tabanomorph family Athericidae. Q. jurassica exhibits adaptations to an aquatic habitat. More importantly, it preserves an unusual combination of features including a thoracic sucker with six radial ridges, unique in insects, piercing-sucking mouthparts for fluid feeding, and crocheted ventral prolegs with upward directed bristles for anchoring and movement while submerged. We demonstrate that Q. jurassica was an aquatic ectoparasitic insect, probably feeding on the blood of salamanders. The finding reveals an extreme morphological specialization of fly larvae, and broadens our understanding of the diversity of ectoparasitism in Mesozoic insects.DOI: http://dx.doi.org/10.7554/eLife.02844.001.

  7. Molecular composition and ultrastructure of Jurassic paravian feathers.

    Science.gov (United States)

    Lindgren, Johan; Sjövall, Peter; Carney, Ryan M; Cincotta, Aude; Uvdal, Per; Hutcheson, Steven W; Gustafsson, Ola; Lefèvre, Ulysse; Escuillié, François; Heimdal, Jimmy; Engdahl, Anders; Gren, Johan A; Kear, Benjamin P; Wakamatsu, Kazumasa; Yans, Johan; Godefroit, Pascal

    2015-08-27

    Feathers are amongst the most complex epidermal structures known, and they have a well-documented evolutionary trajectory across non-avian dinosaurs and basal birds. Moreover, melanosome-like microbodies preserved in association with fossil plumage have been used to reconstruct original colour, behaviour and physiology. However, these putative ancient melanosomes might alternatively represent microorganismal residues, a conflicting interpretation compounded by a lack of unambiguous chemical data. We therefore used sensitive molecular imaging, supported by multiple independent analytical tests, to demonstrate that the filamentous epidermal appendages in a new specimen of the Jurassic paravian Anchiornis comprise remnant eumelanosomes and fibril-like microstructures, preserved as endogenous eumelanin and authigenic calcium phosphate. These results provide novel insights into the early evolution of feathers at the sub-cellular level, and unequivocally determine that melanosomes can be preserved in fossil feathers.

  8. Paleomagnetic studies on sedimentary Jurassic rocks from southern Bulgaria

    Science.gov (United States)

    Kruczyk, J.; Kaḑziałko-Hofmokl, M.; Nozharov, P.; Petkov, N.; Nachev, I.

    Paleomagnetic investigations were performed on Jurassic sediments sampled in the mobile area of Bulgaria comprising Srednogorie, Kreiste and Stranja. The main carriers of magnetic properties of rocks studied are pigmentary haematite and goethite of post-sedimentary origin. The characteristic component of natural remanence (CARM), isolated by means of analysis of demagnetization procedure is secondary, and was acquired after the main tectonic event that took place in this area during the Upper Cretaceous. The CARM directions before tectonic correction are close to the results for Upper Cretaceous magmatic rocks from Srednogorie. The mean CARM direction and the corresponding polar position obtained for the whole region studied are compared with reference data for the Eurasian Platform. The difference between the reference and our data implies anticlockwise rotation of southern Bulgaria relative to Eurasia by ˜ 10-20° and a northward tilt of the region under study by ˜ 10-15° after acquisition of CARM.

  9. Porphyrin geochemistry of Atlantic Jurassic-Cretaceous black shales

    Energy Technology Data Exchange (ETDEWEB)

    Baker, E.W.; Louda, J.W.

    1986-01-01

    Late Jurassic-early Cretaceous black shales and an overlying sequence of Albian-Campanian zeolitic claystones from the Falkland Plateau (DSDP/IPOD Leg 71, Site 511) were analyzed for tetrapyrrole pigment type and abundance. The black shale sequence was found to be rich in DPEP-series dominated free-base, nickel (Ni) and, to a lesser extent, vanadyl (V = 0) porphyrins. A low level of organic maturity (i.e. precatagenesis) is indicated for these strata as nickel chelation by free-base porphyrins is only 50-75% complete, proceeding down-hole to 627 meters sub-bottom. Electronic and mass spectral data reveal that the proposed benzo-DPEP (BD) and tetrahydrobenzo-DPEP (THBD) series are present in the free-base and Ni species, as well as the more usual occurrence in V = 0 porphyrin arrays. Highly reducing conditions are suggested by an abundance of the PAH perylene, substantial amounts of the THBD/BD series and a redox equilibrium between free-base DPEP and 7,8-dihydro-DPEP series, which exist in a 7:1 molar ratio. The Albian-Campanian claystone strata were found to be tetrapyrrole poor, and those pigments present were typed as Cu/Ni highly dealkylated (C/sub 26/ max.) etioporphyrins, thought to be derived via redeposition and oxidation of terrestrial organic matter (OM). Results from the present study are correlated to their past analyses of Jurassic-Cretaceous sediments from Atlantic margins in an effort to relate tetrapyrrole quality and quantity to basin evolution and OM sources in the proto-Atlantic.

  10. Triassic-Jurassic Mass Extinction: Evidence for Bolide Impact?

    Science.gov (United States)

    Perry, R.; Becker, L.; Haggart, J.; Poreda, R.

    2003-04-01

    The Triassic-Jurassic (TJ) mass extinction event is one of the most severe in geologic history and is one of the five largest in the Phanerozoic with as many as 80% of the species lost. It is also one of the most poorly understood. Only a few geologic sections have been identified for the TJ extinction and most of those are not well preserved. Previously, the paucity of suitable stratigraphic sections has prevented corroborative geochemical studies. Recently a well-preserved stratigraphic section spanning the Triassic-Jurassic boundary (˜200 mya) was identified at Kennecott Point, Queen Charlotte, Islands, British Columbia. Initial studies have shown that the Kennecott Point sequence is one of the best preserved and contains one of the most complete radiolarian microfossil turnovers known. Analyses of stable isotopes have shown that a 13C perturbation exits within the sequence and suggests a decline in organic productivity (Ward et al., 2001). Preliminary results of laser desorption mass spectrometry (LDMS) of selected Queen Charlotte samples suggest that fullerenes (C60 to C200) may be present in the Kennecott Point stratigraphic sequence. Previous studies have shown that fullerenes are present in the mass extinction boundary of the Permian-Triassic (˜251 mya) as well as the well-known "dinosaur" extinction event of the Cretaceous-Tertiary (˜65 mya). Therefore, three of the big five extinction events appear to have associated fullerenes. The possible presence of fullerenes along with the productivity collapse (rapid environmental change) suggests that a cometary or asteroidal impact may have occurred. Although no known impact crater exists, we hope to present chemical evidence that an impact or multiple impacts may have been responsible for the TJ mass extinction.

  11. On the analysis of the high-resolution sequence stratigraphy and coal accumulating law of jurassic in Ordos Basin

    Institute of Scientific and Technical Information of China (English)

    LI Zeng-xue; HAN Mei-lian; LI Jiang-tao; YU Ji-feng; L(U) Da-wei; LIU Han-feng

    2008-01-01

    The strata of Jurassic was divided into three tectonic sequences and eight se-quences of third rank, according to the developing feature of the tectonic inconformity and the transforming feature of the depositional system tracts. Also the identification and the division of the base-level cycle of different period were carded through. Therefore three cycles of super period, eight cycles of long period, twenty-four cycles of middle period and some cycles of short pedod were identified. From the overall character of the coal-accu-mulation in the Mesozoic, we can see that the Yan'an formation is of the best nature of coal bearing. When the coal bearing systems of Jurassic were depositing, the Ordos area is the coal accumulating basin of terrene of large scale and located in the same tectonic unit. But the local structure of different part and the paleolandform are different in the basin,which resulted in the difference of the depositional environment. So the layer number and the distribution of the thickness of the coal beds are different in the different part of the ba-sin. The coal-accumulating action migrated regularly along with the development, evolve-ment and migration of the depositional systems. The layer numbers of the coal beds,which can be mined, are more in the north and west fringe of the basin, whose distributing area is extensive, and they are more steady in the landscape orientation, also the total thickness is great. Therefore the nature of coal bearing and the coal-accumulating action of different part changed obviously in the space in Ordos area.

  12. Anaglyph: Patagonia, Argentina

    Science.gov (United States)

    2000-01-01

    This view of northern Patagonia, near El Cain, Argentina shows complexly eroded volcanic terrain, with basalt mesas, sinkholes, landslide debris, playas, and relatively few integrated drainage channels. Surrounding this site (but also extending far to the east) is a broad plateau capped by basalt, the Meseta de Somuncura. Here, near the western edge of the plateau, erosion has broken through the basalt cap in a variety of ways. On the mesas, water-filled sinkholes (lower left) are most likely the result of the collapse of old lava tubes. Along the edges of the mesas (several locations) the basalt seems to be sliding away from the plateau in a series of slices. Water erosion by overland flow is also evident, particularly in canyons where vegetation blankets the drainage channels (bright patterns, bottom of image). However, overland water flow does not extend very far at any location. This entire site drains to local playas, some of which are seen here (dark lakes with bright shores). While the water can reach the playas and then evaporate, what becomes of the eroded rock debris? Wind might excavate some of the finer eroded debris, but the fate of much of the missing bedrock remains mysterious.This anaglyph was generated by first draping a Landsat Thematic Mapper image over a topographic map from the Shuttle Radar Topography Mission, then producing the two differing perspectives, one for each eye. When viewed through special glasses, the result is a vertically exaggerated view of the Earth's surface in its full three dimensions. Anaglyph glasses cover the left eye with a red filter and the right eye with a blue filter.Landsat satellites have provided visible light and infrared images of the Earth continuously since 1972. SRTM topographic data match the 30-meter (99-foot) spatial resolution of most Landsat images and provide a valuable complement for studying the historic and growing Landsat data archive. The Landsat 7 Thematic Mapper image used here was provided to

  13. Stereo Pair: Patagonia, Argentina

    Science.gov (United States)

    2000-01-01

    This view of northern Patagonia, near El Cain, Argentina shows complexly eroded volcanic terrain, with basalt mesas, sinkholes, landslide debris, playas, and relatively few integrated drainage channels. Surrounding this site (but also extending far to the east) is a broad plateau capped by basalt, the Meseta de Somuncura. Here, near the western edge of the plateau, erosion has broken through the basalt cap in a variety of ways. On the mesas, water-filled sinkholes (lower left) are most likely the result of the collapse of old lava tubes. Along the edges of the mesas (several locations) the basalt seems to be sliding away from the plateau in a series of slices. Water erosion by overland flow is also evident, particularly in canyons where vegetation blankets the drainage channels (green patterns, bottom of image). However, overland water flow does not extend very far at any location. This entire site drains to local playas, some of which are seen here (blue). While the water can reach the playas and then evaporate, what becomes of the eroded rock debris? Wind might excavate some of the finer eroded debris, but the fate of much of the missing bedrock remains mysterious.This cross-eyed stereoscopic image pair was generated using topographic data from the Shuttle Radar Topography Mission, combined with an enhanced Landsat 7 satellite color image. The topography data are used to create two differing perspectives of a single image, one perspective for each eye. In doing so, each point in the image is shifted slightly, depending on its elevation. When stereoscopically merged, the result is a vertically exaggerated view of the Earth's surface in its full three dimensions.Landsat satellites have provided visible light and infrared images of the Earth continuously since 1972. SRTM topographic data match the 30-meter (99-foot) spatial resolution of most Landsat images and provide a valuable complement for studying the historic and growing Landsat data archive. The Landsat 7

  14. The Petroleum Characteristics and the Exploration Potential of Cuyo Basin and Neuquen Basin, Argentina%阿根廷库约和内乌肯盆地油气特征与勘探潜力

    Institute of Scientific and Technical Information of China (English)

    童晓光; 琚亮

    2011-01-01

    Located in west-central Argentina, the Cuyo and Neuquen basin are typical Sub-Andean back-arc foreland basins. The differing deformation styles of the lithosphere and fold and thrust belt may be a response to the angle of plate subduction. There are 4 similar basin evolution stages: Basement, Syn-rift, Post-rift and Foreland. A single petroleum system is recognized in Cuyo basin, comprising Triassic organic-rich lacustrine mudstones, Triassic-Jurassic reservoirs and Triassic intraformational as well as Cretaceous regional seals; Traps formed during the Neogene at a similar time to peak oil generation. Three hypothetical and one known petroleum systems occur in Neuquen basin, related to the Upper Triassic, Lower-Middle Jurassic, Valanginian- Barremian and Tithonian-Valanginian source rocks, respectively. Oil and gas has accumulated in reservoir rocks that range in age from Permian to Tertiary, most commercial hydrocarbons are produced from Jurassic and Cretaceous reservoirs. All systems reached the critical moment during the Late Cretaceous-Late Tertiary. The different depositional setting caused different source rock quality. The diversity of their petroleum geological characteristics and the exploration potential are controlled by respective tectonic-sedimentary process.%位于阿根廷中西部地区的库约盆地和内乌肯盆地是南美次安第斯盆地群南段的两个较独特的弧后前陆盆地.俯冲角度的变化导致二者岩石圈及冲断带构造的不同.两个盆地经历了相似的4个盆地演化阶段:基底、裂谷期、后裂谷沉降期、前陆期.库约盆地发育一个已证实的含油气系统,以上三叠统富有机质湖相泥岩为主力烃源岩,主要以三叠系河流相砂砾岩为储层,盖层为三叠系层内盖层和白垩系区域盖层,圈闭形成和油气生成高峰在新近纪.内乌肯盆地发育1个已证实的和3个推测的含油气系统,除裂谷期上三叠统源岩外,其余下-中侏罗统、凡兰

  15. Pediatric intensive care in Argentina.

    Science.gov (United States)

    Schnitzler, E J

    1993-09-01

    8.2% of the gross domestic product is spent annually on health care in Argentina, a country of 32 million people. There is 1 medical doctor of every 147,000 beds in a total 3180 hospitals. The infant mortality rate in Argentina is 24.5/1000 live births which is high compared to developed countries. Perinatal causes and congenital anomalies are the main cause of death after the neonatal period, and accidents, cardiac disease, and respiratory tract infections are the main causes of death among children over age 1 year. Argentina has approximately 35 pediatric intensive care units (ICU), but 154 of 244 beds are within or near the capital. Only 2 hospitals have pediatric intensive care fellowship programs, so full time dedicated staff is rare. 250 registered pediatricians dedicated to intensive care are in the Argentine Pediatric Society and the nurse/bed ratio is 1:2-1:3. Moreover, the country has neither postanesthesia recuperation units, burn units, chronic ventilation units, nor approved home assistance programs, and intermediate care is not clearly standardized. These inadequacies have led to a shortage of beds and the caring for of critically ill children in general pediatric or emergency wards in hospitals which lack adequate equipment; patients are often discharged inappropriately to clear bed space. Even so, prehospital and emergency room care tends to be provided without the necessary coordination with the pediatric ICU, and structural conditions regarding electrical self-sufficiency, air conditioning, and circulation are met in only few units. Despite the existence of these adverse conditions for the care of critically ill children, a pediatric organ transplant program developed since 1987 has demonstrated 70% to 100% survival rates for 16l orthotopic liver and 9 heart transplants, respectively. Alternatives to improving intensive care in Argentina include optimizing the response of emergency and critical care delivery systems, categorizing hospitals and

  16. Post-Jurassic tectonic evolution of Southeast Asia

    Science.gov (United States)

    Zahirovic, Sabin; Seton, Maria; Dietmar Müller, R.; Flament, Nicolas

    2014-05-01

    The accretionary growth of Asia, linked to long-term convergence between Eurasia, Gondwana-derived blocks and the Pacific, resulted in a mosaic of terranes for which conflicting tectonic interpretations exist. Here, we propose solutions to a number of controversies related to the evolution of Sundaland through a synthesis of published geological data and plate reconstructions that reconcile both geological and geophysical constraints with plate driving forces. We propose that West Sulawesi, East Java and easternmost Borneo rifted from northern Gondwana in the latest Jurassic, collided with an intra-oceanic arc at ~115 Ma and subsequently sutured to Sundaland by 80 Ma. Although recent models argue that the Southwest Borneo core accreted to Sundaland at this time, we use volcanic and biogeographic constraints to show that the core of Borneo was on the Asian margin since at least the mid Jurassic. This northward transfer of Gondwana-derived continental fragments required a convergent plate boundary in the easternmost Tethys that we propose gave rise to the Philippine Archipelago based on the formation of latest Jurassic-Early Cretaceous supra-subduction zone ophiolites on Halmahera, Obi Island and Luzon. The Late Cretaceous marks the shift from Andean-style subduction to back-arc opening on the east Asian margin. Arc volcanism along South China ceased by ~60 Ma due to the rollback of the Izanagi slab, leading to the oceanward migration of the volcanic arc and the opening of the Proto South China Sea (PSCS). We use the Apennines-Tyrrhenian system in the Mediterranean as an analogue to model this back-arc. Continued rollback detaches South Palawan, Mindoro and the Semitau continental blocks from the stable east Asian margin and transfers them onto Sundaland in the Eocene to produce the Sarawak Orogeny. The extrusion of Indochina and subduction polarity reversal along northern Borneo opens the South China Sea and transfers the Dangerous Grounds-Reed Bank southward to

  17. Broad-scale patterns of late jurassic dinosaur paleoecology.

    Directory of Open Access Journals (Sweden)

    Christopher R Noto

    Full Text Available BACKGROUND: There have been numerous studies on dinosaur biogeographic distribution patterns. However, these distribution data have not yet been applied to ecological questions. Ecological studies of dinosaurs have tended to focus on reconstructing individual taxa, usually through comparisons to modern analogs. Fewer studies have sought to determine if the ecological structure of fossil assemblages is preserved and, if so, how dinosaur communities varied. Climate is a major component driving differences between communities. If the ecological structure of a fossil locality is preserved, we expect that dinosaur assemblages from similar environments will share a similar ecological structure. METHODOLOGY/PRINCIPAL FINDINGS: This study applies Ecological Structure Analysis (ESA to a dataset of 100+ dinosaur taxa arranged into twelve composite fossil assemblages from around the world. Each assemblage was assigned a climate zone (biome based on its location. Dinosaur taxa were placed into ecomorphological categories. The proportion of each category creates an ecological profile for the assemblage, which were compared using cluster and principal components analyses. Assemblages grouped according to biome, with most coming from arid or semi-arid/seasonal climates. Differences between assemblages are tied to the proportion of large high-browsing vs. small ground-foraging herbivores, which separates arid from semi-arid and moister environments, respectively. However, the effects of historical, taphonomic, and other environmental factors are still evident. CONCLUSIONS/SIGNIFICANCE: This study is the first to show that the general ecological structure of Late Jurassic dinosaur assemblages is preserved at large scales and can be assessed quantitatively. Despite a broad similarity of climatic conditions, a degree of ecological variation is observed between assemblages, from arid to moist. Taxonomic differences between Asia and the other regions demonstrate at

  18. New records of Staffia aenigmatica (Mammalia, Allotheria, Haramiyida from the Upper Jurassic of Tendaguru in southeastern Tanzania, East Africa

    Directory of Open Access Journals (Sweden)

    W.-D. Heinrich

    2001-01-01

    Full Text Available Two non-multituberculate allotherian cheek teeth are described from the Upper Jurassic of Tendaguru in southeastern Tanzania, East Africa, Both specimens were collected from dinosaur-bearing matrix of bone bed Wj of the Middle Saurian Bed at Tendaguru Site dy by the German Tendaguru Expedition (1909–1913. Bone Bed Wj represents limnic to brackish deposits of Kimmeridgian-Tithonian age. The cheek teeth, considered as lower posterior molar and upper molar, represent a single taxon of the Haramiyida and are referred to Staffia aenigmatica, known only from the Upper Jurassic of Tendaguru. This assignment reinforces evidence for the palaeogeographic dispersal of haramiyids to Gondwana and the temporal persistence of these non-multituberculate allotherians into the Late Jurassic. Characters that distinguish Staffia aenigmatica from other haramiyids include the medial position of main cusp a1 at the front of the tooth crown and the presence of a large, anterolingual main notch between cusps a1 and a2 in lower cheek teeth, as well as the development of a strong anterolabial cingular ridge in the only known upper cheek tooth. Staffia shows the closest resemblance to Thomasia from the Late Triassic to Early Jurassic of Europe, although these genera are disdinctly different. Retention of the basic tooth crown pattern of haramiyids and traces of wear in the Tendaguru teeth suggest that the masticatory movements in Staffia were essentially restricted to a longitudinal direction, as in Thomasia. It is suggested that owing to its central position at the front of the tooth crown the lower main cusp a1 could have occluded in the central basin of the opposing upper molar during masticatory movements. Aus dem Oberjura von Tendaguru in Tansania, Ostafrika, werden zwei Backenzähne eines Haramiyiden beschrieben. Beide Zähne stammen aus knochenführenden Gesteinsproben, die von der Deutschen Tendaguru Expedition (1909–1913 in der Fundstelle dy gesammelt wurden

  19. Mida õpetab Argentina finantskriis? / Karsten Staehr

    Index Scriptorium Estoniae

    Staehr, Karsten, 1962-

    2002-01-01

    Norra majandusanalüütik kirjeldab Argentina majanduspoliitikat, analüüsib tehtud vigu ning hoiatab avatud majandusega Eestit võimalike tulevaste välisshokkide eest. Diagramm: SKP kasv ja üleüldine riigieelarve tasakaal 1991-2001 Argentinas

  20. A new Batillipedidae (Tardigrada, Arthrotardigrada) from Argentina.

    Science.gov (United States)

    Menechella, Agustín G; Bulnes, Verónica N; Cazzaniga, Néstor J

    2015-10-16

    A new species of marine tardigrade, Batillipes acuticauda sp. n., has been found in midlittoral sand sediments collected at Monte Hermoso beach (Buenos Aires province, Argentina). The new species differs from all other members of Batillipedidae by its combination of caudal apparatus, lateral processes and toe patterns. It is the first description of an arthrotardigrade from Argentina.

  1. Lower Jurassic beds with bivalves in south Slovenia

    Directory of Open Access Journals (Sweden)

    Irena Debeljak

    1995-12-01

    Full Text Available The Lower Jurassic beds of south Slovenia outcrop on a surface of several hundred km^ with their thickness in places exceeding 300 meters. They were deposited on the Dinaric Carbonate Platform. In them rich accumulations of characteristic bivalves occur that in Pliensbachian and Toarcian inhabited the wide interconnected shallow water regions of the western and southern margins of Tethysand the eastern Pacific. The most interesting are three large bivalve species:Lithiotis problematica, Cochlearites loppianus and Lithiopedalion scutatus.In addition, numerous other genera can be found: Gervilleiopema, Mytilus, Opisoma and Pachyrisma (with subgenera Pachymegalodon and Durga.The bivalves formed in the region of south Slovenia, in the prevailingly quiet environment of the restricted shelf, sea-bottom mats or biostromes. Their shells can be only rarely found in their growth position. The horizon with bivalves ("lithiotid horizon" in south Slovenia is attributed to Pliensbachian (Domerian. It isup to 75 metres thick and it almost does not pinch out. Within it individual lumachelles of bivalves occur which are from several centimetres to ten metres thick.They are almost exclusively associated with dark, micritic, in places marly limestone and bituminous dolomite. The biodiversity in lumachelles is very low. The intermediate beds that do not contain bivalves mostly consist of oolitic and biospariticlimestone. In this article some localities from various areas of the carbonate platform are described. Considered are paleogeographical and paleoecological conditions that permitted the existence of this typical bivalve fauna.

  2. Neuroanatomy of the marine Jurassic turtle Plesiochelys etalloni (Testudinata, Plesiochelyidae).

    Science.gov (United States)

    Carabajal, Ariana Paulina; Sterli, Juliana; Müller, Johannes; Hilger, André

    2013-01-01

    Turtles are one of the least explored clades regarding endocranial anatomy with few available descriptions of the brain and inner ear of extant representatives. In addition, the paleoneurology of extinct turtles is poorly known and based on only a few natural cranial endocasts. The main goal of this study is to provide for the first time a detailed description of the neuroanatomy of an extinct turtle, the Late Jurassic Plesiochelysetalloni, including internal carotid circulation, cranial endocast and inner ear, based on the first digital 3D reconstruction using micro CT scans. The general shape of the cranial endocast of P. etalloni is tubular, with poorly marked cephalic and pontine flexures. Anteriorly, the olfactory bulbs are clearly differentiated suggesting larger bulbs than in any other described extinct or extant turtle, and indicating a higher capacity of olfaction in this taxon. The morphology of the inner ear of P. etalloni is comparable to that of extant turtles and resembles those of slow-moving terrestrial vertebrates, with markedly low, short and robust semicircular canals, and a reduced lagena. In P. etalloni the arterial pattern is similar to that found in extant cryptodires, where all the internal carotid branches are protected by bone. As the knowledge of paleoneurology in turtles is scarce and the application of modern techniques such as 3D reconstructions based on CT scans is almost unexplored in this clade, we hope this paper will trigger similar investigations of this type in other turtle taxa.

  3. Mosquitoes of Middle America.

    Science.gov (United States)

    1976-09-30

    FL; (I S) Museu de Zoologia da (Jniversidade de Sao Paulo , Instituto Adolfo Lu tz in Sao Paulo and Instituto de Microbiologia , Un iversidade...Herbert C., Inst ituto de Microbiologia , Universidade Federal do Rio de Janeiro , Brazil. — Facilities for topotypic survey of mosquitoes in Rio de...976 17 Garcia , M iguel, Departamento de Entomologia Sanitaria , Instituto de Microbiologia , Buenos Aires, Argentina . — Mosquitoes from Argentina

  4. en Argentina en los noventa

    Directory of Open Access Journals (Sweden)

    Marcelo Fabián Delfini

    2005-01-01

    Full Text Available Se analizan los efectos de la implantación de las políticas económicas neoliberales desde 1990 en Argentina sobre la distribución del ingreso y la pobreza, en un marco en que el crecimiento económico no provocó disminuciones sustantivas sobre las variables en estudio. Se emplea el concepto de “estancamiento dinámico ” para analizar las variables propuestas, pues éste sí permite dar cuenta de las regulaciones vigentes durante la década en estudio.

  5. Bioceres: AG Biotechnology from Argentina

    Directory of Open Access Journals (Sweden)

    Roberto Feeney

    2016-04-01

    Full Text Available In this case we present a business decision-making situation in which the CEO of an Argentine Ag Biotech company, Bioceres, has to decide the best way to commercialize a new drought-tolerant transgenic technology. The company was founded by twenty three farmers, who shared a common dream that Argentina could become a benchmark in the development of Ag biotechnology. The case has strategic and financial implications, as well as decision-making situation involving a joint venture with an American biotechnology company. It also introduces to discussion the business models of Ag biotechnology companies in developing countries.

  6. The Oldest Jurassic Dinosaur: A Basal Neotheropod from the Hettangian of Great Britain.

    Science.gov (United States)

    Martill, David M; Vidovic, Steven U; Howells, Cindy; Nudds, John R

    2016-01-01

    Approximately 40% of a skeleton including cranial and postcranial remains representing a new genus and species of basal neotheropod dinosaur is described. It was collected from fallen blocks from a sea cliff that exposes Late Triassic and Early Jurassic marine and quasi marine strata on the south Wales coast near the city of Cardiff. Matrix comparisons indicate that the specimen is from the lithological Jurassic part of the sequence, below the first occurrence of the index ammonite Psiloceras planorbis and above the last occurrence of the Rhaetian conodont Chirodella verecunda. Associated fauna of echinoderms and bivalves indicate that the specimen had drifted out to sea, presumably from the nearby Welsh Massif and associated islands (St David's Archipelago). Its occurrence close to the base of the Blue Lias Formation (Lower Jurassic, Hettangian) makes it the oldest known Jurassic dinosaur and it represents the first dinosaur skeleton from the Jurassic of Wales. A cladistic analysis indicates basal neotheropodan affinities, but the specimen retains plesiomorphic characters which it shares with Tawa and Daemonosaurus.

  7. The Oldest Jurassic Dinosaur: A Basal Neotheropod from the Hettangian of Great Britain.

    Directory of Open Access Journals (Sweden)

    David M Martill

    Full Text Available Approximately 40% of a skeleton including cranial and postcranial remains representing a new genus and species of basal neotheropod dinosaur is described. It was collected from fallen blocks from a sea cliff that exposes Late Triassic and Early Jurassic marine and quasi marine strata on the south Wales coast near the city of Cardiff. Matrix comparisons indicate that the specimen is from the lithological Jurassic part of the sequence, below the first occurrence of the index ammonite Psiloceras planorbis and above the last occurrence of the Rhaetian conodont Chirodella verecunda. Associated fauna of echinoderms and bivalves indicate that the specimen had drifted out to sea, presumably from the nearby Welsh Massif and associated islands (St David's Archipelago. Its occurrence close to the base of the Blue Lias Formation (Lower Jurassic, Hettangian makes it the oldest known Jurassic dinosaur and it represents the first dinosaur skeleton from the Jurassic of Wales. A cladistic analysis indicates basal neotheropodan affinities, but the specimen retains plesiomorphic characters which it shares with Tawa and Daemonosaurus.

  8. Early Jurassic allotherians from South Wales (United Kingdom

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    W. A. Clemens

    2007-02-01

    Full Text Available Fossils from two fissure fillings in Pant Quarry (designated Pant 4 and Pant 5, South Wales, United Kingdom, probably of Early Jurassic age document a taxonomically diverse vertebrate fauna, the Morganucodon-sphenodont fauna, composed of several kinds of reptiles, non-mammalian synapsids, and mammals. Six isolated molariform teeth from Pant 4 and 5 fissures clearly record the presence of Thomasia (Mammalia, Allotheria, Haramiyidae, a genus previously known only from purported Late Triassic faunas of southwestern England, France, Belgium, Luxemburg, Germany, and Switzerland. Small morphological differences from teeth in the larger English and continental European samples warrant identification of the Welsh material as Thomasia cf. moorei. The highly derived morphology of an isolated molariform tooth from Pant 5 fissure indicates the presence of another, possibly allotherian, taxon. Fossilien aus zwei wahrscheinlich unterjurassischen Spaltenfüllungen (Pant 4 und Pant 5 im Steinbruch Pant in Süd-Wales dokumentieren eine taxonomisch diverse Wirbeltierfauna. Diese Morganucodon-Sphenodontiden-Fauna besteht aus verschiedenen Formen von Reptilien, Synapsiden und Säugetieren. Sechs isolierte molariforme Zähne aus den Spaltenfüllungen Pant 4 und Pant 5 belegen eindeutig das Vorkommen von Thomasia (Mammalia, Allotheria, Haramiyidae, einer bisher nur aus vermutlich obertriassischen Faunen Südwest-Englands, Frankreichs, Belgiens, Luxemburgs, Deutschlands und der Schweiz bekannten Gattung. Geringe morphologische Unterschiede zu dem umfangreicheren Material aus England und Kontinental-Europa sprechen für die Identifikation des neuen Materials als Thomasia cf. moorei. Die stark abgeleitete Morphologie eines isolierten molariformen Zahnes aus der Spalte Pant 5 belegt das Vorkommen eines anderen Taxons, das möglicherweise auch den Allotheria zuzuordnen ist. doi:10.1002/mmng.200600018

  9. Quantitative Analysis of Paleoatmospheric CO2 Level Based on Stomatal Characters of Fossil Ginkgo from Jurassic to Cretaceous in China

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A better theoretical and practical understanding of the linkage between paleo-CO2 and climate during geological history is important to enhance the sustainable development of modern human society. Development in plant physiology since the 1980s has led to the realization that fossil plants can serve as a proxy for paleoatmosphere and paleobiosphere. As a relict gymnosperm with evolutionary stasis, Ginkgo is well suited for paleoenvironmental reconstruction. This paper analyzes fossil Ginkgo species from integrated strata in the north of China using anatomic data of plant physiology. Using stomatal parameters, a trend for the paleo-CO2 level during the Early-Middle Jurassic and the Early Cretaceous was obtained, which is consistent with the estimates by GEOCARB.The trend is also similar to that of Mean Global Surface Temperature in geological time. Compared with three other atmospheric CO2 concentration parameters, the trend of paleo-CO2 level based on the stomatal parameter of the fossil Ginkgo specimens from three contiguous strata is more exact.

  10. [The health system of Argentina].

    Science.gov (United States)

    Belló, Mariana; Becerril-Montekio, Victor M

    2011-01-01

    This paper describes the health system of Argentina.This system has three sectors: public, social security and private.The public sector includes the national and provincial ministries as well as the network of public hospitals and primary health care units which provide care to the poor and uninsured population. This sector is financed with taxes and payments made by social security beneficiaries that use public health care facilities. The social security sector or Obras Sociales (OS) covers all workers of the formal economy and their families. Most OS operate through contracts with private providers and are financed with payroll contributions of employers and employees. Finally, the private sector includes all those private providers offering services to individuals, OS beneficiaries and all those with private health insurance.This sector also includes private insurance agencies called Prepaid Medicine Enterprises, financed mostly through premiums paid by families and/or employers.This paper also discusses some of the recent innovations implemented in Argentina, including the program Remediar.

  11. A note on the discovery of the suturocavate dinoflagellate cyst (Limbodinium absidatum) in the Middle East (Binalud Mountains, NE Iran)

    Science.gov (United States)

    Mafi, Abradat; Ghasemi-Nejad, Ebrahim; Ashouri, Alireza; Vahidi-Nia, Mohammad

    2014-04-01

    Limbodinium absidatum is a suturocavate dinocyst that is being reported here from the Binalud Mountains, NE Iran, which is also the first record of this rare species from the Middle East. A few specimens of L. absidatum are recorded from samples taken from the Dalichai Formation at a section measured at Ghoroneh. The stratigraphic range of this species (Late Callovian-Early Oxfordian) is very important for Jurassic palynologists. Morphological characteristics of this Sexiform species are described in detail to support the identification.

  12. A New Sauropod, Gongxianosaurus, from the Lower Jurassic of Sichuan, China

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The paper describes an early and primitive sauropod dinosaur, Gongxianosaurus shibeiensis (gen. et sp. nov.), from the Dongyuemiao Member of the Lower Jurassic Ziliujing Formation in Shibei Township, Gongxian County, Sichuan Province, China, which is one of the 5 dinosaur fossils discovered in Gongxian in 1997. Except the skull which is incomplete, the fossils are well preserved. It has some features of both sauropods and prosauropods. It is an intermediate type in the evolution of dinosaurs from prosauropods to sauropods and provides materials for the study of the origin and evolution of the sauropod dinosaur fauna. The discovery of this new sauropod furnishes a way for the stratigraphic correlation between the Early Jurassic Ziliujing Formation in the Sichuan basin and the Lower Jurassic Lufeng Formation in the Central Yunnan basin.

  13. Sistema de salud de Argentina The health system of Argentina

    Directory of Open Access Journals (Sweden)

    Mariana Belló

    2011-01-01

    Full Text Available En este artículo se describe el sistema de salud de Argentina, que está compuesto por tres sectores: público, de seguridad social y privado. El sector público está integrado por los ministerios nacional y provincial, y la red de hospitales y centros de salud públicos que prestan atención gratuita a toda persona que lo demande, fundamentalmente a personas sin seguridad social y sin capacidad de pago. Se financia con recursos fiscales y recibe pagos ocasionales de parte del sistema de seguridad social cuando atiende a sus afiliados. El sector del seguro social obligatorio está organizado en torno a las Obras Sociales (OS, que aseguran y prestan servicios a los trabajadores y sus familias. La mayoría de las OS operan a través de contratos con prestadores privados y se financian con contribuciones de los trabajadores y patronales. El sector privado está conformado por profesionales de la salud y establecimientos que atienden a demandantes individuales, a los beneficiarios de las OS y de los seguros privados. Este sector también incluye entidades de seguro voluntario llamadas Empresas de Medicina Prepaga que se financian sobre todo con primas que pagan las familias y/o las empresas. En este trabajo también se describen las innovaciones recientes en el sistema de salud, incluyendo el Programa Remediar.This paper describes the health system of Argentina.This system has three sectors: public, social security and private.The public sector includes the national and provincial ministries as well as the network of public hospitals and primary health care units which provide care to the poor and uninsured population. This sector is financed with taxes and payments made by social security beneficiaries that use public health care facilities. The social security sector or Obras Sociales (OS covers all workers of the formal economy and their families. Most OS operate through contracts with private providers and are financed with payroll

  14. Interbasinal marker intervals——A case study from the Jurassic basins of Kachchh and Jaisalmer, western India

    Institute of Scientific and Technical Information of China (English)

    PANDEY; Dhirendra; Kumar; FüRSICH; Franz; Theodor

    2009-01-01

    The Kachchh Basin and the Jaisalmer Basin are two neighboring Mesozoic sedimentary basins at the western margin of the Indian craton. The Jurassic succession of the Kachchh Basin is more complete and more fossiliferous than that of the Jaisalmer Basin. Consequently, intrabasinal correlation of the sedimentary units has been possible in the Kachchh Basin, but not in the Jaisalmer Basin. However, some marker beds existing in the Kachchh Basin can be recognized also in the Jaisalmer Basin. Ammonite evidence shows that they are time-equivalent. The following four units form marker intervals in both basins: (1) the pebbly rudstone unit with Isastrea bernardiana and Leptosphinctes of the Kaladongar Formation (Kachchh Basin) and the Isastrea bernardiana-bearing rudstone of the Jaisalmer Formation (Jaisalmer Basin) both represent transgressive systems tract deposits dated as Late Bajocian; (2) bioturbated micrites with anomalodesmatan bivalves within the Goradongar Yellow Flagstone Member (Kachchh Basin) and bioturbated units in the Fort Member (Jaisalmer Basin) represent maximum flooding zone deposits of the Middle to Late Bathonian; (3) trough-crossbedded, sandy packto grainstones of the Raimalro Limestone Member (Kachchh Basin) and the basal limestone-sandstone unit of the Kuldhar section of the Jaisalmer Formation (Jaisalmer Basin) correspond to Late Bathonain transgressive systems tract deposits; and (4) ferruginous ooid-bearing carbonates with hardgrounds of the Dhosa Oolite member (Kachchh Basin) and the middle part of the Jajiya Member (Jaisalmer Basin) are Oxfordian transgressive systems tract deposits. The fact that in both basins similar biofacies prevailed during certain time intervals demonstrates a common control of their depositional history. As the two basins represent different tectonic settings, the most likely controlling factors were the relative sea-level changes produced by eustatic processes, a common subsidence history of the northwestern margin of

  15. Androecium of Archaefructus, the Late Jurassic Angiosperms from Western Liaoning, China

    Institute of Scientific and Technical Information of China (English)

    SUN Ge; ZHENG Shaolin; SUN Chunlin; SUN Yuewu; David L. DILCHER; MIAO Yuyan

    2002-01-01

    Androecium of the earliest known flowering plant Archaefructus liaoningensis was found from the Upper Jurassic Jianshangou Formation of western Liaoning, China. The androecium consists of numerous stamens bearing in pair on the reproductive axes below conduplicate carpels. The stamens are composed of a short filament and basifixed anther for each. Monosulcate pollen in situ are found from the anthers. The characters of the androecium reveals that Archaefructus are probably protandrous, and the paired stamens and monosulcate pollen appear to indicate that Archaefructus, as primitive angiosperms,might be derived from extinct seed -ferns during the Older Mesozoic. Archaefructus is considered Late Jurassic in age.

  16. A basal alvarezsauroid theropod from the early Late Jurassic of Xinjiang, China.

    Science.gov (United States)

    Choiniere, Jonah N; Xu, Xing; Clark, James M; Forster, Catherine A; Guo, Yu; Han, Fenglu

    2010-01-29

    The fossil record of Jurassic theropod dinosaurs closely related to birds remains poor. A new theropod from the earliest Late Jurassic of western China represents the earliest diverging member of the enigmatic theropod group Alvarezsauroidea and confirms that this group is a basal member of Maniraptora, the clade containing birds and their closest theropod relatives. It extends the fossil record of Alvarezsauroidea by 63 million years and provides evidence for maniraptorans earlier in the fossil record than Archaeopteryx. The new taxon confirms extreme morphological convergence between birds and derived alvarezsauroids and illuminates incipient stages of the highly modified alvarezsaurid forelimb.

  17. Jurassic Lake T'oo'dichi': a large alkaline, saline lake, Morrison Formation, eastern Colorado Plateau

    Science.gov (United States)

    Turner, C.E.; Fishman, N.S.

    1991-01-01

    Recognition of alkaline, saline-lake deposits in the Morrison Formation significantly alters interpretations of depositional environments of this formation, and it also has important implications for paleoclimatic interpretation. Late Jurassic climate was apparently much more arid than had previously been thought. In fact, sedimentologic evidence suggests that the lake basin was typically dry for extended periods and enjoyed only brief wet intervals. This conclusion has important consequences for environmental interpretation of the habitat that was favorable for large herbivorous dinosaurs, which thrived in the Late Jurassic. -from Authors

  18. Earliest evolution of multituberculate mammals revealed by a new Jurassic fossil.

    Science.gov (United States)

    Yuan, Chong-Xi; Ji, Qiang; Meng, Qing-Jin; Tabrum, Alan R; Luo, Zhe-Xi

    2013-08-16

    Multituberculates were successful herbivorous mammals and were more diverse and numerically abundant than any other mammal groups in Mesozoic ecosystems. The clade also developed diverse locomotor adaptations in the Cretaceous and Paleogene. We report a new fossil skeleton from the Late Jurassic of China that belongs to the basalmost multituberculate family. Dental features of this new Jurassic multituberculate show omnivorous adaptation, and its well-preserved skeleton sheds light on ancestral skeletal features of all multituberculates, especially the highly mobile joints of the ankle, crucial for later evolutionary success of multituberculates in the Cretaceous and Paleogene.

  19. Argentina: entre o Mercosul e a Alca

    Directory of Open Access Journals (Sweden)

    Raúl Bernal-Meza

    2001-12-01

    Full Text Available Este artigo procura mostrar que a Argentina não está numa encruzilhada na sua política externa, tendo que escolher entre Mercosul ou Alca. Ao contrário, a Argentina vê o Mercosul como um caminho que leva à Alca, afirmando uma posição que se tornou possível depois da confluência de outros fatores, como a posição brasileira frente a Alca e o modelo de integração regional proposta para o Mercosul.This article seeks to show that Argentina is not in crossroads in your foreign policy, having to choose between Mercosur and FTAA. In contrast, Argentina sees Mercosur as a way that leads to FTAA, affirming a position that become possible after a confluence of others factors, as the Brazilian position front Alca and the model of regional integration proposal for Mercosur.

  20. Polar record of Early Jurassic massive carbon injection

    Science.gov (United States)

    Suan, Guillaume; Nikitenko, Boris L.; Rogov, Mikhail A.; Baudin, François; Spangenberg, Jorge E.; Knyazev, Valeriy G.; Glinskikh, Larisa A.; Goryacheva, Anna A.; Adatte, Thierry; Riding, James B.; Föllmi, Karl B.; Pittet, Bernard; Mattioli, Emanuela; Lécuyer, Christophe

    2011-12-01

    The Toarcian Oceanic Anoxic Event (T-OAE) (ca. 182 Myr, Early Jurassic) represents one of the best-recognized examples of greenhouse warming, decreased seawater oxygenation and mass extinction. The leading hypothesis to explain these changes is the massive injection of thermogenic or gas hydrate-derived 13C-depleted carbon into the atmosphere, resulting in a > 3 per mil negative carbon isotope excursion (CIE), accelerated nutrient input and dissolved oxygen consumption in the oceans. Nevertheless, the lack of a precisely dated record of the T-OAE outside low latitudes has led to considerable debate about both its temporal and spatial extent and hence concerning its underlying causes. Here we present new isotopic and lithological data from three precisely dated N Siberian sections, which demonstrate that mass extinction and onset of strong oxygen-deficiency occurred near synchronously in polar and most tropical sites and were intimately linked to the onset of a marked 6‰ negative CIE recorded by bulk organic carbon. Rock Eval pyrolysis data from Siberia and comparisons with low latitudes show that the CIE cannot be explained by the extent of stratification of the studied basins or changes in organic matter sourcing and suggest that the negative CIE reflects rapid 13C-depleted carbon injection to all exchangeable reservoirs. Sedimentological and palynological indicators show that the injection coincided with a change from cold (abundant glendonites and exotic boulder-sized clasts) to exceptionally warm conditions (dominance of the thermophyllic pollen genus Classopollis) in the Arctic, which likely triggered a rapid, possibly partly glacioeustatic sea-level rise. Comparisons with low latitude records reveal that warm climate conditions and poor marine oxygenation persisted in continental margins at least 600 kyr after the CIE, features that can be attributed to protracted and massive volcanic carbon dioxide degassing. Our data reveal that the T-OAE profoundly

  1. The palaeogeography of Sundaland and Wallacea since the Late Jurassic

    Directory of Open Access Journals (Sweden)

    Robert Hall

    2013-08-01

    Full Text Available The continental core of Southeast (SE Asia, Sundaland, was assembled from Gondwana fragments by the Early Mesozoic. Continental blocks rifted from Australia in the Jurassic [South West (SW Borneo, East Java-West Sulawesi-Sumba], and the Woyla intraoceanic arc of Sumatra, were added to Sundaland in the Cretaceous. These fragments probably included emergent areas and could have carried a terrestrial flora and fauna. Sarawak, the offshore Luconia-Dangerous Grounds areas, and Palawan include Asian continental material. These probably represent a wide accretionary zone at the Asia-Pacific boundary, which was an active continental margin until the mid Cretaceous. Subduction ceased around Sundaland in the Late Cretaceous, and from about 80 Ma most of Sundaland was emergent, physically connected to Asia, but separated by deep oceans from India and Australia. India moved rapidly north during the Late Cretaceous and Early Cenozoic but there is no evidence that it made contact with SE Asia prior to collision with Asia. One or more arc-India collisions during the Eocene may have preceded India-Asia collision. The arcs could have provided dispersal pathways from India into SE Asia before final suturing of the two continents. During the Late Cretaceous and Early Cenozoic there was no significant subduction beneath Sumatra, Java and Borneo. At about 45 Ma Australia began to move north, subduction resumed and there was widespread rifting within Sundaland. During the Paleogene east and north Borneo were largely submerged, the Makassar Straits became a wide marine barrier within Sundaland, and West Sulawesi was separated from Sundaland but included land. By the Early Miocene the proto-South China Sea had been eliminated by subduction leading to emergence of land in central Borneo, Sabah and Palawan. Australia-SE Asia collision began, eliminating the former deep ocean separating the two continents, and forming the region now known as Wallacea. The microplate or

  2. Structure and climate controls on the evolution of a Mid-Late Jurassic alluvial fan-delta system in the western part of Yanshan fold-and-thrust belt

    Science.gov (United States)

    Lin, Chengfa; Liu, Shaofeng; Yao, Xiang; Ma, Pengfei

    2016-04-01

    The Yanshan fold-thrust belt experienced several significant tectonic events during Mesozoic time and developed thrust fault-bounded intramontane sedimentary basins. However, elaborate works of sedimentology is inadequate in the Yanshan belt, particularly in its western segment, leading to a failure in comprehensively understanding how bounding-faults and climate change influence the basin filling processes. Our detailed sedimentological study of the Middle Jurassic Xiahuayuan Formation and Upper Jurassic-Lower Cretaceous Jiulongshan Formation in the Xiahuayuan basin of northern Hebei province, indicates a genetic relationship between the evolution of an alluvial fan-delta system and the tectonic and climate setting. The Xiahuayuan Formation was assigned to a debris flow-dominated Gilbert-type fan-delta composed of topset conglomerates, foreset massive siltstone-fine grained sandstone interbedded with lenticular conglomerate units and bottomset/lake bottom fine-grained deposits, spatially restricted to the northern part of the basin. While the lower Jiulongshan Formation was considered as a relatively small debris flow- and turbidity currents-dominated fan-delta with a single-ramp portrait, prograding into the middle part of the basin. And the upper part of Jiulongshan Formation contributed to the lake bottom component of the delta system during the forming of the Jiulongshan Formation. Our results reveal a transformation of a fan-delta from Gilbert-type to single-ramp type and the basinward migration of this fan-delta during Mid-Late Jurassic in the Xiahuayuan basin. And it is assumed that the activity of a thrust fault along the northern basin margin and the rapid switch of climate conditions from warm and humid to hot and dry triggered the transformation and migration of this fan-delta system.

  3. Espacios nacionales y espacios regionales. Conflictos y concertaciones en las fronteras chaqueñas de Argentina, Bolivia y Paraguay

    OpenAIRE

    Figallo, Beatriz J.

    2003-01-01

    From the end of the nineteenth century until the middle of the twentieth, the Gran Chaco was a zone of conflict. Argentina, Bolivia and Paraguay exercised varied and competing influences in the region, reflecting the intentions of each nation to incorporate the Chaco forcibly as part of larger projects of industrialisation and colonisation. This study examines the implementation of these projects, as well as the resistance they generated in the face of the violence visited upon the inhabitant...

  4. China, Argentina agree to further strategic ties

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    According to Xinhua,China and Argentina have agreed to further enhance mutual trust and their strategic partnership as the two emerging economies are playing an increasingly important role in the world arena.“China will work with Argentina to strengthen strategic mutual trust,expand cooperation and coordination within multilateral frameworks in order to promote bilateral ties and benefit the two peoples,” Vice President Xi Jinping told Argentine Foreign Minister Hector Timerman on September 9.

  5. Evidence for avian intrathoracic air sacs in a new predatory dinosaur from Argentina.

    Directory of Open Access Journals (Sweden)

    Paul C Sereno

    Full Text Available BACKGROUND: Living birds possess a unique heterogeneous pulmonary system composed of a rigid, dorsally-anchored lung and several compliant air sacs that operate as bellows, driving inspired air through the lung. Evidence from the fossil record for the origin and evolution of this system is extremely limited, because lungs do not fossilize and because the bellow-like air sacs in living birds only rarely penetrate (pneumatize skeletal bone and thus leave a record of their presence. METHODOLOGY/PRINCIPAL FINDINGS: We describe a new predatory dinosaur from Upper Cretaceous rocks in Argentina, Aerosteon riocoloradensis gen. et sp. nov., that exhibits extreme pneumatization of skeletal bone, including pneumatic hollowing of the furcula and ilium. In living birds, these two bones are pneumatized by diverticulae of air sacs (clavicular, abdominal that are involved in pulmonary ventilation. We also describe several pneumatized gastralia ("stomach ribs", which suggest that diverticulae of the air sac system were present in surface tissues of the thorax. CONCLUSIONS/SIGNIFICANCE: We present a four-phase model for the evolution of avian air sacs and costosternal-driven lung ventilation based on the known fossil record of theropod dinosaurs and osteological correlates in extant birds: (1 Phase I-Elaboration of paraxial cervical air sacs in basal theropods no later than the earliest Late Triassic. (2 Phase II-Differentiation of avian ventilatory air sacs, including both cranial (clavicular air sac and caudal (abdominal air sac divisions, in basal tetanurans during the Jurassic. A heterogeneous respiratory tract with compliant air sacs, in turn, suggests the presence of rigid, dorsally attached lungs with flow-through ventilation. (3 Phase III-Evolution of a primitive costosternal pump in maniraptoriform theropods before the close of the Jurassic. (4 Phase IV-Evolution of an advanced costosternal pump in maniraptoran theropods before the close of the Jurassic

  6. Evidence for Avian Intrathoracic Air Sacs in a New Predatory Dinosaur from Argentina

    Science.gov (United States)

    Sereno, Paul C.; Martinez, Ricardo N.; Wilson, Jeffrey A.; Varricchio, David J.; Alcober, Oscar A.; Larsson, Hans C. E.

    2008-01-01

    Background Living birds possess a unique heterogeneous pulmonary system composed of a rigid, dorsally-anchored lung and several compliant air sacs that operate as bellows, driving inspired air through the lung. Evidence from the fossil record for the origin and evolution of this system is extremely limited, because lungs do not fossilize and because the bellow-like air sacs in living birds only rarely penetrate (pneumatize) skeletal bone and thus leave a record of their presence. Methodology/Principal Findings We describe a new predatory dinosaur from Upper Cretaceous rocks in Argentina, Aerosteon riocoloradensis gen. et sp. nov., that exhibits extreme pneumatization of skeletal bone, including pneumatic hollowing of the furcula and ilium. In living birds, these two bones are pneumatized by diverticulae of air sacs (clavicular, abdominal) that are involved in pulmonary ventilation. We also describe several pneumatized gastralia (“stomach ribs”), which suggest that diverticulae of the air sac system were present in surface tissues of the thorax. Conclusions/Significance We present a four-phase model for the evolution of avian air sacs and costosternal-driven lung ventilation based on the known fossil record of theropod dinosaurs and osteological correlates in extant birds: (1) Phase I—Elaboration of paraxial cervical air sacs in basal theropods no later than the earliest Late Triassic. (2) Phase II—Differentiation of avian ventilatory air sacs, including both cranial (clavicular air sac) and caudal (abdominal air sac) divisions, in basal tetanurans during the Jurassic. A heterogeneous respiratory tract with compliant air sacs, in turn, suggests the presence of rigid, dorsally attached lungs with flow-through ventilation. (3) Phase III—Evolution of a primitive costosternal pump in maniraptoriform theropods before the close of the Jurassic. (4) Phase IV—Evolution of an advanced costosternal pump in maniraptoran theropods before the close of the

  7. Poverty and Health in Argentina

    Directory of Open Access Journals (Sweden)

    Maria Alejandra Silva

    2009-06-01

    Full Text Available This article examines health conditions in the rural areas of Central Argentina, the country’s main region for soy-bean production and export. Health conditions are analyzed through the concepts of emerging and re-emerging diseases in a context of increasing poverty. Data on poverty and health was obtained from both primary sources (trade union, government officials, rural doctors and the South Watch/FA/FODEPAL/UNR working group and secondary sources (IPEC/INDEC, IDESA, Consultora Equis, the Argentine Ministry of Employment, ILO, the Ministry of Health, the Ministry of the Environment, toxicology centers and rural doctors. Analysis of rural health conditions gives cause for concern. There is evidence of deterioration in the social determinants of health such as an increase in rural and urban poverty associated with informal employment and child labor. At the same time lack of government epidemiological and toxicological data appears to hide or distort the reality of health conditions.

  8. Soybean biomass produced in Argentina

    DEFF Research Database (Denmark)

    Semino, Stella; Paul, Helena; Tomei, Julia

    Soybean biomass for biodiesel, produced in Argentina amongst other places, is considered by some to reduce greenhouse gas emissions and mitigate climate change when compared with fossil fuel. To ensure that the production of biofuels is ‘sustainable', EU institutions and national governments...... are currently designing certification schemes for the sustainable production of biomass. This paper questions the validity of proposed environmental standards, using the production of Argentine soybean as a case study. The production of soybean production is associated with profound environmental impacts...... generates emissions of N2O. The large quantity of substances, sprayed by terrestrial and aerial means, has negative impacts on biodiversity, water, soil, and human and animal health. The intensive production of soybeans also leads to social impacts, including loss of livelihoods and food sovereignty...

  9. Guido Bonarelli, explorador y gelogo incansable: pionero en la prospeccin de hidrocarburos en la Argentina Guido Bonarelli, tireless explorer and geologist: pioneer in the prospection of hydrocarbons in Argentina

    Directory of Open Access Journals (Sweden)

    Andrea Concheyro

    2011-09-01

    of Jurassic ammonites and the stratigraphy of the Central Apennines. His professional work began in Italy and continued in Southeast Asia, South America, Bolivia, Chile, Argentina and Uruguay. During 1911-1918, he worked in the Direccin General de Minas, Geologa e Hidrografa of Argentina. He defined the Sub-Andean Ranges as an orographic complex and he pointed out the locations of oil and natural gas reservoirs. He developed his researches in several Argentinean provinces and in the pacific Chilean coast. During his second period of research in Argentina (1923 -1927, Guido Bonarelli organized the Geological Division of YPF, and he intensified the oil exploration in the northwestern of Argentina, as well as in the provinces of Mendoza, Neuqun and the Comodoro Rivadavia region. He developed a professional and academic team that dealt with the geology and the hydrocarbon exploration in the country. Bonarelli discovered in 1891 a sedimentary horizon that has great importance and it serves as a baseline to characterize the global anoxic event known to the Cenomanian-Turonian transition. This world-famous skyline has been named Livello Bonarelli as a posthumous tribute to his discoverer.

  10. Spanish Coastal Patrol Ships for Argentina and Mexico (Guardacostas Espanoles para Argentina y Mejico),

    Science.gov (United States)

    1983-12-22

    GABARRUS TRANSLATED BY: LT GREGORY STOVER, USNR-R NISC TRANSLATION UNIT 0166 SOURCE: TECNOLOGIA MILITAR, NO. 4, 1983; PP. 50, 53-54; SPANISH DTIC S ELECTE...SHIPS FOR ARGENTINA AND MEXICO [Ramirez Gabarrus, M.; Guardacostas espaioles para Argentina y Mejico; Tecnologia Militar, No. 4, 1983; pP. 50, 53-54

  11. Argentina

    Directory of Open Access Journals (Sweden)

    Guillermina Fernández Zambón

    2005-01-01

    Full Text Available La actividad industrial, de cualquier época, tiene una gran importancia para el hombre, pues al igual que el resto de los procesos económicos, es el reflejo del accionar cotidiano de la sociedad sobre el espacio. Considerando esto, el presente articulo tiene como objetivo presentar al patrimonio industrial como recurso para organizar rutas turísticas que permitan en algunos casos recuperar espacios industriales abandonados o usar establecimientos industriales en funcionamiento pero que pueden incorporarse a este tipo de desarrollo turístico. La creación de rutas turísticas puede permitir la reactivación de las economías locales, por constituirse en definitiva en una nueva actividad económica. Para lograr esto es necesario articular el sector público y el privado. De esta forma es posible, a través de la creación de rutas turísticas del patrimonio industrial, generar un desarrollo turístico local sustentable.

  12. Strobilus organization in the enigmatic gymnosperm Bernettia inopinata from the Jurassic of Germany

    NARCIS (Netherlands)

    Kustatscher, E.; van Konijnenburg - van Cittert, J.H.A.; Bauer, K.; Krings, M.

    2016-01-01

    The enigmatic fossil Bernettia inopinata from Lower Jurassic strata of Upper Franconia, Germany, has been described as a leaf-like structure a leaf-like structure bearing a proximal cluster of densely spaced, pillow-like objects believed to represent ovules or ovule-containing units. The systematic

  13. The upper Jurassic-lower cretaceous siliciclastic system in the Morocco offshore - Prevenance, transport and deposition

    NARCIS (Netherlands)

    Bertotti, G.; Arantegui, A.; Charton, R.; Luber, T.; Redfern, J.

    2015-01-01

    The Morocco segment of the Central Atlantic passive continental margin experienced km-scale exhumation during the early post-rift (late Jurassic-Early Cretaceous). In the Meseta and the High Atlas this led to the development of a N-S trending ridge sourcing terrigenous sediments which were brought t

  14. Klukiopsis jurassica——A new Jurassic schizaeaceous fern from China

    Institute of Scientific and Technical Information of China (English)

    邓胜徽[1; 王仕俊[2

    2000-01-01

    A new Jurassic schizaeaceous fern Klukiopsis jurassica gen. et sp. nov. from Yima, Henan Province, China is described. The new fern is characterized by the abaxial sori arranged in two rows, apical and complete annulus and more than 800 smooth trilete spores in each sorus.

  15. Architecture of an Upper Jurassic barrier island sandstone reservoir, Danish Central Graben:

    DEFF Research Database (Denmark)

    Johannessen, Peter N.; Nielsen, Lars H.; Nielsen, Lars

    2010-01-01

    An unusually thick (c. 88 m), transgressive barrier island and shoreface sandstone succession characterizes the Upper Jurassic Heno Formation reservoir of the Freja oil field situated on the boundary of Denmark and Norway. The development and preservation of such thick transgressive barrier islan...... such that the island aggraded and even prograded seawards and became wider and longer due to the large surplus of sand....

  16. New finds of stegosaur tracks from the Upper Jurassic Lourinhã formation, Portugal

    DEFF Research Database (Denmark)

    Mateus, Octavio; Milàn, Jesper; Romano, Michael;

    2011-01-01

    Eleven new tracks from the Upper Jurassic of Portugal are described and attributed to the stegosaurian ichnogenus Deltapodus. One track exhibits exceptionally well−preserved impressions of skin on the plantar surface, showing the stegosaur foot to be covered by closely spaced skin tubercles of ca...

  17. The potential of vertebrate microfossils for marine to non-marine correlation in the Late Jurassic

    Institute of Scientific and Technical Information of China (English)

    Detlev Thies; Alexander Mudroch; Susan Turner

    2007-01-01

    Fish (cartilaginous: elasmobranch and bony: osteichthyan actinopterygian) and reptile (crocodile) microfossils comprising scales and teeth have been examined from a series of limestone samples in the Upper Jurassic of France and Germany to gauge the possibilities of using them for correlation between fully marine and hypo- or hyper-saline (non-marine) deposits.

  18. Geochemical Characteristics of REE in Jurassic Coal of Yan'an Formation from Dongsheng Coalfield

    Institute of Scientific and Technical Information of China (English)

    赵峰华; 丛志远; 彭苏萍; 唐跃刚; 任德贻

    2002-01-01

    Concentrations of rare earth elements (REE) in Jurassic coal of YanAn Formation from Dongsheng coalfield located in the northeast of Ordos basin were determined by instrumental neutron activation analysis (INAA). Curves of distrib ution pattern of REE were drawn, and many geochemical parameters were calculated . The result shows that 1) The contents of REE in Jurassic coal with low ash an d sulfur are lower than those of Carboniferous and Permian coal from the Basin of North China; 2) Inside the Dongsheng coalfield, coal from the north has high er contents of REE than that form the south because the north is near the area of source rock which is the main supplier of REE, while the south is far away from the area of source rocks; 3) Although Jurassic coal in Dongsheng is the low-ash coal with less than 10%, the contents of REE are still proportional to ash yie ld of ash and SiO2 contents. 4) Although the Jurassic coal in Dongsheng were deposited in oxidative continental environment of river-lake, Eu depletion of RE E I n coal commonly exists, and positive abnormity of Ce dose not exist. This reflec ts the REE distribution pattern of REE in source rock of continental area; and 5) Compared with other rocks, coal shows extremely complexity of distribution pa ttern of REE, which is the result of continuous alteration and redistribution of matter in coal occurred in open basin system.

  19. Battling Jurassic Park: From a Fascination with Violence toward Constructive Knowledge.

    Science.gov (United States)

    Cain, Beverlyn; Bohrer, Cynthia

    1997-01-01

    Studied preschool children's inability to distinguish fantasy from fact utilizing the case of the popular movie Jurassic Park and the subsequent false information children obtained about dinosaurs. Described attempts made by teachers to address the resultant aggressive behavior and false knowledge gained and replace it with constructive knowledge.…

  20. Palynology of uppermost Jurassic and lowermost Cretaceous strata in the Eastern Netherlands

    NARCIS (Netherlands)

    Burger, D.

    1965-01-01

    The present investigation is a systematical treatment of the sporomorphs from strata at the Jurassic-Cretaceous boundary in the eastern Netherlands Twente area, and an attempt to apply palynology to detailed stratigraphical study, by making use of quantitative pollen analyses. The rock samples used

  1. Evolutionary and Ecological Sequelae of Mass Extinctions: Examples From the Continental Triassic-Jurassic Boundary

    Science.gov (United States)

    Olsen, P. E.; Whiteside, J. H.

    2003-12-01

    The Triassic-Jurassic boundary at ˜200 Ma marks one of the five major mass-extinctions of the Phanerozoic and, depending on the metrics used, was similar in magnitude to the K-T mass extinction. In continental environments about 50% of all tetrapod families are eliminated and although floral diversity change is difficult to gauge, a similar proportion of palynomorph taxa disappear at the boundary. The extinction event appears to have been very abrupt, followed by a roughly 900 ky super-greenhouse period characterized by increased precipitation. We hypothesize a series of biological consequences of the drop in diversity and associated super-greenhouse based on observations of the earliest Jurassic assemblages, largely from eastern North America. 1) The drop in diversity results in a collapse of ecological interactions that tend to stabilize the composition of regional biotas and buffer them from invading forms. Triassic assemblages show considerable biogeographic provinciality despite the existence of Pangea, but the earliest Jurassic assemblages were extraordinarily homogenous with many vertebrate genera being essentially global in distribution. 2) Initially the post-boundary terrestrial assemblages were comprised of eurytopic trophic generalists, with animal communities with few herbivores, but abundant carnivores and detritivores subsisting on aquatic-based food webs. The earliest Jurassic tetrapod footprint record is overwhelmingly dominated by the footprints of ceratosaurian theropod dinosaurs, the latter having skull characteristics usually associated at least in part with piscivory. 3) The dramatic size changes over very short periods of time were likely due to an absence of competition (i.e., ecological release). The maximum size of theropod dinosaur footprints increased by about 25% within 10 ky following the boundary, corresponding to a doubling of mass. 4) Representatives of clades with intrinsically high rates of speciation tend to form species flocks

  2. 77 FR 45653 - Lemon Juice From Argentina and Mexico

    Science.gov (United States)

    2012-08-01

    ...)] Lemon Juice From Argentina and Mexico Institution of five-year reviews concerning the suspended investigations on lemon juice from Argentina and Mexico. AGENCY: United States International Trade Commission... the suspended investigations on lemon juice from Argentina and Mexico would be likely to lead...

  3. Psychiatry and humanism in Argentina.

    Science.gov (United States)

    Niño Amieva, Alejandra

    2016-04-01

    The authors of the present selection of Latin American Psychiatry texts were characterized by a common deep humanistic attitude. These prolific writers were able to establish or extend the scope of the discipline in which they chose to act, questioning the establishment of rigid boundaries within the framework of a rigorous epistemological reflection. Thus the systematizing spirit of Jose Ingenieros' in the context of positivist evolutionism, resulted in the act of founding a discipline that integrated the biological and the social. In the case of Guillermo Vidal his conception of mental health went beyond the biomedical to consider psychotherapies as an emotional commitment, continence and empathic understanding; with regard to César Cabral his formation and extensive clinical practice resulted in a work defined by the inquiring into the theoretical concepts underlying Psychiatry and Clinical Psychology. This brief selection does not exhaust the issues or the level of ideas and discussions of Psychiatry in Argentina, but constitutes a textual corpus representative of a disciplinary conception understood as scientific and humanistic endeavor.

  4. Crocodyliform footprints from “les couches rouges” of the Middle Jurassic of Msemrir, High Atlas, Morocco

    OpenAIRE

    Hadri, Majid; Boutakiout, Mohamed; GÓMEZ, Fernando; Pérez Lorente, Félix

    2015-01-01

    Se describen dos huellas crocodyliformes de “les couches rouges” del Jurásico Medio del Alto Atlas de las que se destaca su importancia por su escasez en el registro mundial. Las huellas no son comparables con los icnogéneros descritos hasta ahora. La huella del pie es incompleta. Suponemos que es un crocodiliforme continental porque el ambiente sedimentario en el que están las icnitas es fluvial. Finalmente se indica, aunque con unos márgenes de inseguridad amplios, el orde...

  5. Argentina to fully privatize state owned YPF

    Energy Technology Data Exchange (ETDEWEB)

    1992-10-05

    Argentina's Congress has voted to fully privatize state petroleum company Yacimientos Petroliferos Fiscales (YPF), a move the government expects to net at least $8 billion. Despite some political opposition, the vote was 119-10 in favor, with one abstention and opposition party members refusing to participate in the vote. Argentina's President Carlos Menem had threatened to authorize YPF privatization by decree if there was no quorum for a vote. YPF is responsible for 40% of Argentina's oil production. The country h as been self-sufficient in crude since 1982. Current production is 563,472 b/d, and proved reserves of oil and gas are valued at $7 billion.

  6. Titanium and oxygen isotope diffusion in quartz-phenocrysts from a Jurassic rhyolite, Chon Aike Province (Fitz Roy, Patagonia)

    Science.gov (United States)

    Seitz, S.; Putlitz, B.; Baumgartner, L. P.; Escrig, S.; Meibom, A.; Leresche, S.; Vennemann, T. W.

    2014-12-01

    The volcanic El Quemado Complex was deposited during the breakup of Gondwana during the Middle and Late Jurassic. It is part of a large silicic igneous province, which includes the Chon Aike Province in Southern Patagonia and related rocks from the Antarctic Peninsula [1]. The Complex consists of rhyolitic and dacitic ignimbrites and air-fall tuffs, intercalated with andesitic to rhyolitic lava flows. New LA-ICPMS U/Pb-dates of zircons from the Fitz Roy area yield ages between 148 and 153Ma. No inherited zircons were found, suggesting that the temperature of 850°C calculated from zircon saturation is a minimum temperature. Lava flows are typically rich in quartz phenocrysts, which preserved magmatic trace element zoning, as revealed by cathodoluminescence (CL): light cores are surrounded by several darker and lighter zones towards the rim. The δ18O-values for quartz of between 11 to 14 ‰ are compatible with a crustal source for the magma and the SIMS analyses of phenocrysts reveal no zoning in O-isotope compositions. High-resolution Ti-profiles were obtained by NanoSIMS with a beam size of ~200 nm and a minimum step size of ~120 nm. Several lines perpendicular to the magmatic zoning of the quartz-phenocrysts were measured. The profiles show sharp changes in the 48Ti/29Si-ratio over a distance of 5 μm, which correlate with CL-intensity changes. The profiles can be used for diffusion chronometry. The distances obtained from NanoSIMS profiles were used to calculate maximum diffusional relaxation times. Assuming a step function as initial condition and extrusion temperatures from zircon saturation of 850°C, we obtain a maximum residence time for the quartz-phenocrysts of 3.5 years. [1] Pankhurst R.J., Riley T.R., Fanning C.M., Kelley S.P., 2000. J. Pet., 41, 605-625.

  7. Jurassic carbonate microfacies, sea-level changes and the Toarcian anoxic event in the Tethys Himalaya (South Tibet)

    Science.gov (United States)

    Han, Zhong; Hu, Xiumian; Garzanti, Eduardo

    2016-04-01

    Detailed microfacies analysis of carbonate rocks from the Tingri and Nyalam areas of South Tibet allowed us to reconstruct the evolution of sedimentary environments during the Early to Middle Jurassic. Based on texture, sedimentary structure, grain composition and fossil content of about 500 thin sections, 17 microfacies overall were identified, and three evolutionary stages were defined. Stage 1 (Rhaetian?-lower Sinemurian Zhamure Formation) was characterized by siliciclastic and mixed siliciclastic-carbonate sedimentation on a barrier shore environment, stage 2 (upper Sinemurian-Pliensbachian Pupuga Formation) by high-energy grainstones with rich benthic faunas thriving on a carbonate platform, and stage 3 (Toarcian-lower Bajocian Nieniexiongla Formation) by low-energy mudstones intercalated with frequent storm layers on a carbonate ramp. Besides, Carbon isotope analyses (δ13Ccarb and δ13Corg) were performed on the late Pliensbachian-early Toarcian interval, and the organic matter recorded a pronounced stepped negative excursion -4.5‰ corresponding to characteristics of the early Toarcian oceanic anoxic event globally, which began just below the stage 2-stage 3 facies shifting boundary. The comparison between the Tethys Himalaya (South Tibet) and the tropical/subtropical zones of the Western Tethys and Panthalassa was carried out to discuss the factors controlling sedimentary evolution. The change from stage 1 to stage 2 was possibly induced by sea-level rise, when the Tibetan Tethys Himalaya was located at tropical/subtropical latitudes in suitable climatic and ecological conditions for carbonate sedimentation. The abrupt change from stage 2 to stage 3 is interpreted as a consequence of the early Toarcian oceanic anoxic event, accompanied by obvious carbon-isotope negative excursion and sea-level rise. The failed recovery from the carbonate crisis in the early Bajocian, with continuing deposition on a low-energy carbonate ramp, is ascribed to the tectonic

  8. Faunal associations, paleoecology and paleoenvironment of marine Jurassic rocks in the Mae Sot, Phop Phra, and Umphang areas, western Thailand

    Institute of Scientific and Technical Information of China (English)

    MEESOOK; Assanee; YAMEE; Chotima; SAENGSRICHAN; Wirote

    2009-01-01

    We here report a paleoecological analysis and depositional history of the marine Jurassic (Toarcian–early Bajocian) strata cropping out in the western part of Thailand, based on bivalve assemblages with additional data from ammonites, brachiopods, and microfossils. Generally, the benthic bivalve facies in most outcrops is rich in infaunal, semi-infaunal and epifaunal suspension-feeders. Of these, infaunal forms dominate. The diversity of this benthic assemblage was influenced by energy level, substrate, sedimentation rate, and salinity. Low to intermediate energy levels and rather soft fine-grained siliciclastic substrate are proposed as factors governing faunal distribution and explaining the greater abundance and diversity of infaunal than epifaunal suspension-feeders. There were paleoenvironmental changes both in space and time, i.e., from south to north (Umphang to Mae Sot) and from Early Bajocian to Toarcian. In the Toarcian, most outcrops in Umphang are dominated by benthic bivalve facies (infaunal, semi-infaunal, and epifaunal associations). This implies warm, shallow water (inner neritic, 50―100 m) and oxygenated conditions except for the Mae Sot area where a deeper setting (outer neritic to possibly upper continental slope, 50―200 m) with restricted basinal anoxic conditions is favored as indicated by the presence of Bositra. After higher energy conditions in the Toarcian, lower energy conditions with low sediment supplies prevail in the Alenian, and the Mae Sot area was still a restricted basin. As a result of higher sea levels, the oxygen content in the basin is increased, resulting in the presence of the ammonites. By the end of the Alenian-early Bajocian, an ammonite-bivalve association (mixed facies A) and the presence of corals and microfauna (mixed facies B) are dominant but pass upwards to near-shore higher energy conditions in most areas except for restricted basin in Mae Sot. By the middle Bajocian the environment in all areas had changed

  9. On the occurrence and implications of Jurassic primary continental boninite-like melts in the Zagros orogen

    Science.gov (United States)

    Esna-Ashari, A.; Tiepolo, M.; Hassanzadeh, J.

    2016-08-01

    Ultramafic rocks, ranging from pyroxenites to hornblendites, are associated with granitoids of the Aligoodarz intrusive complex in the central Sanandaj-Sirjan Zone, representing the Mesozoic continental arc segment of the Zagros orogen. As inferred from the ultramafic whole rock composition and the most primitive clinopyroxene composition in pyroxenites, the geochemical signature of primary melt is significantly different from that of the continental arc basalts. In particular, primary melt is characterized by extremely low concentrations of incompatible elements and high concentrations of Mg and refractory elements typical of boninites. Amphibole is a late crystallizing mineral in these rocks and is in textural and chemical disequilibrium with olivine + orthopyroxene + clinopyroxene. Amphibole crystallized from a liquid underwent differentiation through a process of melt-rock reaction. In particular, early differentiated boninitic cumulates reacted with later melts with a strong crustal signature similar to Aligoodarz granodiorite. Usbnd Pb zircon geochronology from ultramafic rocks and surrounding quartz-diorite yield similar ages and indicate that they are coeval with Aligoodarz granitoids (ca. 165-170 Ma). However, the occurrence of a marked negative Eu anomaly in zircon from the ultramafic rocks, which is absent in the boninitic primary melt, indicates that zircons crystallized from the infiltrating melt and in turn date the timing of melt infiltration. The interaction between ultramafic cumulates and infiltrated melt has generated a new liquid compositionally similar to high-Mg andesites and to the quartz-diorites hosting the ultramafic cumulates. The scenario that better account for the genesis of boninitic melts in the Sanandaj-Sirjan Zone is partial melting of a depleted mantle wedge in response to the onset of NeoTethys subduction. According to this hypothesis, middle Jurassic calc-alkaline magmatism in the Sanandaj-Sirjan Zone represents the mature stage

  10. Dynamic paleogeography of the Jurassic Andean Basin: pattern of transgression and localisation of main straits through the magmatic arc

    Directory of Open Access Journals (Sweden)

    J-C. Vicente

    2005-03-01

    Full Text Available The paleogeographic evolution of the Jurassic Andean retroarc basin is examined at a global scale for the Central Andes. In this paper, it is called for the striking continuity and lasting of the active volcanic arc. Both direct and indirect sedimentologic evidences allow to locate the western border (insular of the basin and opposite it with the eastern border (cratonic. Emphasis is placed on the volcaniclastic deposits and synsedimentary structures associated with this insular border. It is concluded that the arc magmatic activity has contributed considerably in sediment supply to the basin. Extent and continuity of the arc implies to locate the straits connecting with the Paleopacific. Systematic check of the time of transgressions coupled with sequential facies analysis provides a dynamic outlook of the transgressive process. Sectors with early transgression allow to distinguish two main gulfs of passage through the arc from which waters have progressed lengthwise at the same time northward and southward in a narrow retroarc furrow : the first at latitude of Taltal (25°S, the second at latitude of Curepto (35°S. Both initiated in the upper Triassic and extended during the Hettangian. The evolution as separate basins (Tarapacá and Aconcagua-Neuquén ended by fusion in middle Pliensbachian giving rise to a continuous elongated basin from Chubut to northern Peru. The remarkable continuity and narrowness of the Andean Basin leaves no doubt about its tectonic control. This stems to its geotectonic setting as a typical retroarc basin adjacent to a very active magmatic arc and explains the extreme mobility of its insular margin characterized by a huge volcanoclastic apron with associated debris flows and turbidites.

  11. Stratigraphic and geochemical evolution of an oceanic arc upper crustal section: The Jurassic Talkeetna Volcanic Formation, south-central Alaska

    Science.gov (United States)

    Clift, P.D.; Draut, A.E.; Kelemen, P.B.; Blusztajn, J.; Greene, A.

    2005-01-01

    The Early Jurassic Talkeetna Volcanic Formation forms the upper stratigraphic level of an oceanic volcanic arc complex within the Peninsular Terrane of south-central Alaska. The section comprises a series of lavas, tuffs, and volcaniclastic debris-How and flow turbidite deposits, showing significant lateral facies variability. There is a general trend toward more volcaniclastic sediment at the top of the section and more lavas and tuff breccias toward the base. Evidence for dominant submarine, mostly mid-bathyal or deeper (>500 m) emplacement is seen throughout the section, which totals ???7 km in thickness, similar to modern western Pacific arcs, and far more than any other known exposed section. Subaerial sedimentation was rare but occurred over short intervals in the middle of the section. The Talkeetna Volcanic Formation is dominantly calc-alkatine and shows no clear trend to increasing SiO2 up-section. An oceanic subduction petrogenesis is shown by trace element and Nd isotope data. Rocks at the base of the section show no relative enrichment of light rare earth elements (LREEs) versus heavy rare earth elements (REES) or in melt-incompatible versus compatible high field strength elements (HFSEs). Relative enrichment of LREEs and HFSEs increases slightly up-section. The Talkeetna Volcanic Formation is typically more REE depleted than average continental crust, although small volumes of light REE-enriched and heavy REE-depleted mafic lavas are recognized low in the stratigraphy. The Talkeetna Volcanic Formation was formed in an intraoceanic arc above a north-dipping subduction zone and contains no preserved record of its subsequent collisions with Wrangellia or North America. ?? 2005 Geological Society of America.

  12. ON THE PRESENCE OF PYRAMIODONTHERIUM (MAMMALIA, XENARTHRA, MEGATHERIIDAE IN THE LATE MIOCENE OF NORTHEASTERN ARGENTINA AND ITS BIOGEOGRAPHICAL IMPLICATIONS

    Directory of Open Access Journals (Sweden)

    DIEGO BRANDONI

    2009-03-01

    Full Text Available The biochron of the subfamily Megatheriinae, large to very large terrestrial sloths typified by Megatherium Cuvier, in Argentina extends from the middle Miocene of Patagonia to the late Pleistocene-early Holocene. Megatheriines reached their highest diversity in the lower levels (="conglomerado osífero", late Miocene of the Ituzaingó Formation in Entre Ríos Province, northeastern Argentina. Among the four megatheriines that occur in this unit, the genera Promegatherium Ameghino, Eomegatherium Kraglievich and Pliomegatherium Kraglievich represent relatively small to medium-sized taxa. Here we describe new material assigned to Pyramiodontherium, the largest of the four genera from the same bed and comparable in size to some Quaternary species of Megatherium. Three valid species of Pyramiodontherium have been recognized, all distributed mainly in northwestern Argentina, from the late Miocene in Catamarca Province (and probably also in Tucumán Province, and the late Pliocene in La Rioja Province. The presence of this genus in northeastern Argentina extends its known paleobiogeographical distribution. 

  13. Devonian-Carboniferous unconformity in Argentina and its relation to the Eo-Hercynian orogeny in southern South America

    Science.gov (United States)

    López-Gamundí, O. R.; Rossello, E. A.

    1993-04-01

    The Devonian-Carboniferous contact in southern South America, characterized by a sharp unconformity, has been related to the Late Devonian-Early Carboniferous Eo-Hercynian orogeny. The Calingasta-Uspallata basin of western Argentina and the Sauce-Grande basin (Ventana Foldbelt) of eastern Argentina have been selected to characterize this unconformity. The Eo-Hercynian movements were accompanied in western Argentina by igneous activity related to a Late Devonian—Early Carboniferous magmatic arc mainly exposed today along the Andean Cordillera. This magmatic activity is partly reflected also in eastern Argentina (Ventana Foldbelt), where isotopic dates suggest a thermal event also related to the intrusions present to the west in the North Patagonian Massif and Sierras Pampeanas. The scarcity of Lower Carboniferous deposits in the stratigraphic record of southern South America suggests that the Early Carboniferous was a time interval dominated by uplift and erosion followed by widespread subsidence during the Middle and Late Carboniferous. The origin of the Eo-Hercynian orogeny can be linked with the convergence between the Arequipa Massif, and its southern extension, and the South American continent. Its effects are best represented along the ‘Palaeo-Pacific’ margin, although distant effects are discernible in the cratonic areas of eastern South America.

  14. Two theropod track assemblages from the Jurassic of Chongqing, China, and the Jurassic Stratigraphy of Sichuan Basin%重庆晚侏罗世两处兽脚类足迹组合与四川盆地侏罗纪地层

    Institute of Scientific and Technical Information of China (English)

    邢立达; Martin G.LOCKLEY; 陈伟; Gerard D.GIERLI(N)SKI; 李建军; W.Scott PERSONSIV; 松川正树; 叶勇; Murray K.GINGRAS

    2013-01-01

    重庆市已报道了4处侏罗纪的恐龙足迹点,包括下侏罗统珍珠冲组的大足化石点,该地点发现了中国迄今最古老的蜥脚类行迹;另外两处化石点(南岸和金鸡)的层位曾被视为中或上侏罗统,这里首次将其确认为上侏罗统上沙溪庙组;第4处化石点(成渝),本文全部作者目前都未曾观察,这里不做描述.南岸化石点是南岸重庆足迹(Chongqingpus nananensis)模式标本的所在地,位于重庆市中心,曾发现过大量兽脚类足迹,如今已消逝在城市化进程中.幸运的是,这批标本被保存于重庆自然博物馆,本文作者曾前后两次对其进行研究,并得出文中的结论.南岸重庆足迹为中型足迹(平均长约29 cm),最可能被卡岩塔足迹(Kayentapus)所囊括,这批标本中有一些保存着边界不清的拇趾迹.该化石点的其他足迹被归于似异样龙足迹(cf.Anomoepus).其他较小的、来自重庆市周边中侏罗统中部的足迹此前已被归于跷脚龙足迹(Grallator).金鸡化石点保存了一条孤立的兽脚类行迹,因其粗壮的特征而被暂时归于似窄足龙足迹(cf.Therangospodus).金鸡点的行迹也保存了非连续出现的拇趾迹.虽然重庆市和四川盆地及其周边更广泛地区之侏罗纪地层发现的兽脚类足迹日渐增多,但要明确其确切地质年龄及有效的足迹分类依然需要进一步工作.这是因为侏罗纪的恐龙足迹尽管丰富,但显示出连续变化的形态学特征,而保存状况的变化更使其难以在时间与空间上做出定义与鉴别.%Four Jurassic dinosaur tracksites have been reported from Chongqing Municipality.These include the Lower Jurassic Dazu site in the Zhenzhuchong Formation,which yields the oldest sauropod trackway known from China.Two of the remaining three sites (Nan'an,and Jinji sites),variously regarded as Middle and Upper Jurassic,are here described in detail for the first time and regarded as Upper Jurassic,both from

  15. Ticks infesting humans in Northern Misiones, Argentina.

    Science.gov (United States)

    Lamattina, Daniela; Nava, Santiago

    2016-01-01

    This work presents records of ticks infesting humans in northern Misiones Province, Argentina. Also, notes on potential transmission of tick-borne pathogens are included. A total of 282 ticks attached to researchers were collected and identified by their morphological characters. Eight tick species were found: Amblyomma brasiliense, Amblyomma coelebs, Amblyomma dubitatum, Amblyomma incisum, Amblyomma ovale, Haemaphysalis juxtakochi, Rhipicephalus sanguineus and Rhipicephalus microplus. Some of these species as A. dubitatum, A. ovale and R. sanguineus have been found infected with spotted fever group rickettsiae pathogenic to humans in Brazil and Argentina. The potential role as vectors of humans pathogens of the ticks found attached to humans in this study is discussed.

  16. Hepatitis C in Argentina: epidemiology and treatment

    OpenAIRE

    Gaite LA; Marciano S; Galdame OA; Gadano AC

    2014-01-01

    Luis Alejandro Gaite, Sebastián Marciano, Omar Andrés Galdame, Adrián Carlos GadanoHepatology Unit, Hospital Italiano de Buenos Aires, Buenos Aires, ArgentinaAbstract: Hepatitis C is the leading cause of chronic hepatitis, cirrhosis, and liver cancer in Argentina, where from 1.5% to 2.5% of adults are infected. Most of the infections were acquired 30–50 years ago. It is estimated that more than half of infected individuals are not aware of their infe...

  17. de la Argentina y notas nomenclaturales

    Directory of Open Access Journals (Sweden)

    Zulma E. Rúgolo de Agrasar

    2006-01-01

    Full Text Available En esta primera revisión del género Deyeuxia para la Argentina se reconocen 58 taxones nativos de América, tres de ellos son endémicos de la Argentina, y los restantes también crecen en Bolivia, Brasil y Chile. Se describen tres nuevos taxones para la ciencia: Deyeuxia alba subsp. breviaristata (Argentina, Brasil y Uruguay; Deyeuxia heterophylla var. puberilemma (Perú; Deyeuxia trichodonta var. hirsuta (Argentina: Salta. Se establece un nuevo nombre: Deyeuxia nana, para en Agrostis caespitosa. Las siguientes once entidades constituyen nuevas citas para Argentina, Bolivia, Chile y Ecuador: Deyeuxia brevifolia var. brevifolia y Deyeuxia brevifolia var. expansa (Chile; Deyeuxia cabrerae var. cabrerae, D. cabrerae var. aristulata (Chile; D. cabrerae var. trichopoda (Chile; Deyeuxia curta (Ecuador; Deyeuxia filifolia (Chile; D. diemii (Chile; Deyeuxia filifolia (Chile; Deyeuxia hackelii (Chile; Deyeuxia minima (Argentina y Ecuador; Deyeuxia sclerantha (Ecuador; Deyeuxia spicigera var. spicigera (Chile; Deyeuxia spicigera var. cephalotes (Argentina y Deyeuxia trichodonta var. trichodonta (Bolivia. Se establecen cinco nuevas combinaciones: Deyeuxia reitzii, Deyeuxia rupestris f. pilosa., Deyeuxia rupestris var. minor, D. tarmensis var. macrochaeta y Deyeuxia velutina var. nardifolia. Se adicionan nuevos sinónimos en las siguientes entidades: Deyeuxia heterophylla (Calama grostis mulleri, Calamagrostis macbridei; Deyeuxia rupestris f. pilosa (Calamagrostis leonardii, Calamagrostis longearistata f. pilosa y Calamagrostis epigeios (Calamagrostis chilensis. Esta revisión incluye una evaluación crítica de los caracteres morfológicos (algunos estudiados con MEB con valor taxonómico para Deyeuxia y sus especies aquí estudiadas, como también una discusión de las relaciones de Deyeuxia con sus géneros más afines. Se presentan en detalle consideraciones nomenclaturales sobre taxones problemáticos, claves dicotómicas para distinguir Deyeuxia de

  18. First American record of the Jurassic ichnogenus Deltapodus and a review of the fossil record of stegosaurian footprints

    DEFF Research Database (Denmark)

    Milàn, Jesper; Chiappe, Luis M

    2009-01-01

    We describe the first American stegosaur track of the ichnospecies Deltapodus brodricki, collected in the Upper Jurassic Morrison Formation of San Juan County, southeastern Utah, United States. The track is preserved as a natural cast on the underside of a slab of fluvial sandstone and consists o...... and highlights the similarities between the Late Jurassic dinosaur faunas of North America and those of Western Europe....

  19. Dinosaur tracks in Lower Jurassic coastal plain sediments (Sose Bugt Member, Rønne Formation) on Bornholm, Denmark

    DEFF Research Database (Denmark)

    Clemmensen, Lars B; Milàn, Jesper; Pedersen, Gunver K

    2014-01-01

    Fluvial palaeochannels of coastal plain sediments of the Lower Jurassic Sose Bugt Member of the Rønne Formation exposed in the coastal cliffs at Sose Bugt, Bornholm, contain abundant dinosaur or other large vertebrate tracks in the form of deformation structures exposed in vertical section...... track. Contemporary Upper Triassic – Lower Jurassic strata from southern Sweden and Poland contain a diverse track fauna, supporting our interpretation. This is the earliest evidence of dinosaur activity in Denmark....

  20. Paleomagnetism of Jurassic and Cretaceous rocks bounding the Santa Marta massif - NW corner of Colombia, South America

    Science.gov (United States)

    Bayona, G.; Jimenez, G.; Silva, C.

    2008-12-01

    The Santa Marta massif (SMM) is a complex terrain located in the NW margin of South America, bounded by the left-lateral Santa Marta fault to the west and the right-lateral Oca fault to the north. The SMM is cored by Precambrian metamorphic and Jurassic intrusive rocks, whereas along the SE flank crop out Jurassic volcanic rocks overlying unconformably by Limestones of Cretaceous age. Paleomagnetic analysis of 30 sites in the Jurassic and Cretaceous units in the SE region uncovered two principal magnetic components. The component "a", isolated in low coercivity and temperatures, has declinations to the north and moderate positive inclinations representing the actual field direction (n=11, D=347.6 I=23 K=30.77, a95=8.4). The component "c", with high coercivity and temperatures, has two orientations. After two-step tilt corrections, the first has northward declination and positive, low inclination (n=9, D=12, I=3, K=18.99, a95=12.1); this direction was uncovered in Cretaceous and some Jurassic rocks near to the Santa Marta fault, and we consider it as a Cretaceous component. The second direction was uncovered only in Jurassic rocks and has NNE declinations with negative-low inclinations (n=9, D=11.3 I=-14.3 K=12.36, a95=15.2); this direction represents a Jurassic component. Jurassic and Cretaceous directions isolated in areas faraway of the Santa Marta Fault suggest slight clockwise vertical-axes rotation. The Jurassic component suggests northward translation of the SMM from Paleolatitude -7.3, to near the magnetic equador in the Cretaceous, and to northern latitudes in the Cenozoic.

  1. Late Jurassic adakitic granodiorite in the Dong Co area, northern Tibet: Implications for subduction of the Bangong-Nujiang oceanic lithosphere and related accretion of the Southern Qiangtang terrane

    Science.gov (United States)

    Fan, Jian-Jun; Li, Cai; Wu, Hao; Zhang, Tian-Yu; Wang, Ming; Chen, Jing-Wen; Xu, Jian-Xin

    2016-11-01

    In this paper we present new major and trace element chemical data, zircon U-Pb age data, and zircon Hf isotopic compositions for the Dong Co granodiorites (DGs) that were emplaced directly in the Dong Co ophiolites (DOs) in the middle segment of the Bangong-Nujiang suture zone (BNSZ), northern Tibet. We use these new data to discuss the genesis of the DGs and implications for the evolution of the region. The DGs have high contents of SiO2, Al2O3, Na2O, and Sr, high values of Mg#, low contents of Yb and Y, and markedly high Sr/Y ratios, indicating an adakitic affinity, and we show that they were derived from the partial melting of subducted oceanic crust. The DGs contain large numbers of inherited zircons that have similar shapes and peak ages to the detrital zircons in the accretionary wedge graywackes that surround the DGs, suggesting that many of these sediments were assimilated during the formation of the DGs. Five DG samples yield the youngest zircon U-Pb ages of 155-160 Ma, indicating that the DGs formed during the Late Jurassic. Based on the present results and regional geological data, we infer that the Bangong-Nujiang oceanic lithosphere was subducted northwards beneath the Southern Qiangtang terrane during the formation of a continental arc system during the Late Jurassic. The Bangong-Nujiang oceanic lithosphere retreated rapidly after its initial subduction, and the Southern Qiangtang terrane to the north of the Bangong-Nujiang Ocean acquired a massive amount of new oceanic material in the form of an accretionary wedge. This wedge, which included the DOs and the Mugagangri Group, became sufficiently large (both in size and width) for arc-type magmas (DGs) to develop within it during the Late Jurassic.

  2. Distribution patterns of the Jurassic ostreids (Bivalvia) from Tanggula of China

    Institute of Scientific and Technical Information of China (English)

    沙金庚

    2001-01-01

    Distribution of the Jurassic ostreids (Bivalvia) from Tanggula area of China includes three patterns, which are (1) Tethys: containing Liostrea birmanica and Eligmus rollandi, (2) western Europe and northern Tethys: consisting of Gryphaea (Bilobissa) bilobata; and (3) Global: composed of Actinostreon gregareum and Nanogyra nana. However, they are all limited between palaeolatidudes 60° South and North. Actinostreon gregareum originated in the Sinemurian of northern Chile and it entered Kenya and Madagascar in the Toarcian, but there is no reliable Si-nemurian-Toarcian A. gregareum fossil record in continental margins between Chile and Kenya and Madagascar. Such distribution patterns and dispersal processes have demonstrated that (1) during the Jurassic all seas and oceans were connected to each other; (2) the Tethys and the western European epicontinental seas did produce some endemic taxa; (3) the distribution of these ostreids was most likely controlled by latitudes and creature ecology; and (4) A, gr

  3. Natural Gas Resource in Jurassic, Y Faulted Subbasin of Songliao Basin

    Institute of Scientific and Technical Information of China (English)

    Yang Haibo; Hu Yutao; Wei Xinghua

    2000-01-01

    Y faulted depression is located in the southeast of Songliao basin, which is another important area explored for natural gas in deep Formation after Xujiaweizi. But it is lowly explored and is not likely to make a major breakthrough in nature gas exploration for shallow and medium layers. The data on the geochemistry and geology indicate that the deep source rocks, especially the Jurassic mudstone bas great potentials of natural gas generation. Based on this, the paper examines the conditions of natural gas generation and further points out the favorable prospective gas - bearing area. The results show that the amount of natural gas generated from the Jurassic mudstone in the Y faulted depression is 8.42 × 1012m3 and the favorable gas - generating area is the body of the faulted depression.

  4. New evidence of shared dinosaur across Upper Jurassic Proto-North Atlantic: Stegosaurus from Portugal

    Science.gov (United States)

    Escaso, Fernando; Ortega, Francisco; Dantas, Pedro; Malafaia, Elisabete; Pimentel, Nuno L.; Pereda-Suberbiola, Xabier; Sanz, José Luis; Kullberg, José Carlos; Kullberg, María Carla; Barriga, Fernando

    2007-05-01

    More than one century after its original description by Marsh in 1877, we report in this paper the first uncontroversial evidence of a member of the genus Stegosaurus out of North America. The specimen consists of a partial skeleton from the Upper Jurassic of Portugal, herein considered as Stegosaurus cf. ungulatus. The presence of this plated dinosaur in the upper Kimmeridgian-lower Tithonian Portuguese record and synchronic levels of the Morrison Formation of North America reinforces previous hypothesis of a close relationship between these two areas during the Late Jurassic. This relationship is also supported by geotectonic evidences indicating high probability of an episodic corridor between the Newfoundland and Iberian landmasses. Together, Portuguese Stegosaurus discovery and geotectonic inferences could provide a scenario with episodical faunal contact among North Atlantic landmasses during the uppermost Kimmeridgian-lowermost Tithonian (ca. 148-153 Ma ago).

  5. An enigmatic plant-eating theropod from the Late Jurassic period of Chile.

    Science.gov (United States)

    Novas, Fernando E; Salgado, Leonardo; Suárez, Manuel; Agnolín, Federico L; Ezcurra, Martín D; Chimento, Nicolás R; de la Cruz, Rita; Isasi, Marcelo P; Vargas, Alexander O; Rubilar-Rogers, David

    2015-06-18

    Theropod dinosaurs were the dominant predators in most Mesozoic era terrestrial ecosystems. Early theropod evolution is currently interpreted as the diversification of various carnivorous and cursorial taxa, whereas the acquisition of herbivorism, together with the secondary loss of cursorial adaptations, occurred much later among advanced coelurosaurian theropods. A new, bizarre herbivorous basal tetanuran from the Upper Jurassic of Chile challenges this conception. The new dinosaur was discovered at Aysén, a fossil locality in the Upper Jurassic Toqui Formation of southern Chile (General Carrera Lake). The site yielded abundant and exquisitely preserved three-dimensional skeletons of small archosaurs. Several articulated individuals of Chilesaurus at different ontogenetic stages have been collected, as well as less abundant basal crocodyliforms, and fragmentary remains of sauropod dinosaurs (diplodocids and titanosaurians).

  6. Uppermost Jurassic-Lower Cretaceous carbonate deposits from Fara San Martino (Maiella, Italy: biostratigraphic remarks

    Directory of Open Access Journals (Sweden)

    Roberta Bruni

    2007-10-01

    Full Text Available The Uppermost Jurassic-Lower Cretaceous limestone succession in the Maiella region of Italy has been investigated in a profile covering more than 400 m stratigraphical thickness at Fara San Martino. The succession mainly consists of peritidal limestones, intertidal and supratidal sequences being dominant, together with subtidal lagoonal facies. As a consequence, the microfossil assemblages are generally poorly developed, Microfossils occur within the subtidal lagoonal facies of this suite of restricted sediments. This feature led us to recognise five informal biostratigraphic intervals, which are facies related – instead of biozones, each of the intervals being characterized by specific micropaleontological associations. The occurrence and/or disappearance of some marker microfossils were used as references for separating these intervals. Based on these markers, the Uppermost Jurassic-Lower Cretaceous carbonate deposits from Maiella region may be correlated with similar deposits from the Apennines and from other regions in the perimediterranean area.

  7. A new sauropodomorph dinosaur from the Early Jurassic of Patagonia and the origin and evolution of the sauropod-type sacrum.

    Directory of Open Access Journals (Sweden)

    Diego Pol

    Full Text Available BACKGROUND: The origin of sauropod dinosaurs is one of the major landmarks of dinosaur evolution but is still poorly understood. This drastic transformation involved major skeletal modifications, including a shift from the small and gracile condition of primitive sauropodomorphs to the gigantic and quadrupedal condition of sauropods. Recent findings in the Late Triassic-Early Jurassic of Gondwana provide critical evidence to understand the origin and early evolution of sauropods. METHODOLOGY/PRINCIPAL FINDINGS: A new sauropodomorph dinosaur, Leonerasaurus taquetrensis gen. et sp. nov., is described from the Las Leoneras Formation of Central Patagonia (Argentina. The new taxon is diagnosed by the presence of anterior unserrated teeth with a low spoon-shaped crown, amphicoelous and acamerate vertebral centra, four sacral vertebrae, and humeral deltopectoral crest low and medially deflected along its distal half. The phylogenetic analysis depicts Leonerasaurus as one of the closest outgroups of Sauropoda, being the sister taxon of a clade of large bodied taxa composed of Melanorosaurus and Sauropoda. CONCLUSIONS/SIGNIFICANCE: The dental and postcranial anatomy of Leonerasaurus supports its close affinities with basal sauropods. Despite the small size and plesiomorphic skeletal anatomy of Leonerasaurus, the four vertebrae that compose its sacrum resemble that of the large-bodied primitive sauropods. This shows that the appearance of the sauropod-type of sacrum predated the marked increase in body size that characterizes the origins of sauropods, rejecting a causal explanation and evolutionary linkage between this sacral configuration and body size. Alternative phylogenetic placements of Leonerasaurus as a basal anchisaurian imply a convergent acquisition of the sauropod-type sacrum in the new small-bodied taxon, also rejecting an evolutionary dependence of sacral configuration and body size in sauropodomorphs. This and other recent discoveries are

  8. Dynamic Paleogeography of the Jurassic Andean Basin: pattern of regression and general considerations on main features

    Directory of Open Access Journals (Sweden)

    J-C. Vicente

    2006-09-01

    Full Text Available Following examination of the evolution of the Jurassic Andean retroarc basin at a global scale for the Central Andes, this paper analyses the pattern of the regressive process, and discusses some general features concerning Andean Jurassic Paleogeography. The early Upper Jurassic regression obeys to an exactly reverse pattern as the one evidenced for the Lower Jurassic transgressive process. Sectors with late transgressions become those with early regressions while those with early transgressions show later regressions. This fact may indicate that the Norte Chico Isthmus (29°S to 30°30'S was a precociously emerged zone from the Bajocian. This carries again a split up between the Tarapacá and Aconcagua-Neuquén basins until their complete drying up in the Late Oxfordian following their restricted circulation. This evaporitic late stage presents great analogy with the Mediterranean «Messinian crisis» and gives evidence of a general tectonic and magmatic control on the straits. The local transgressions observed on the cratonic margin of the central part of these shrinking basins were due to shifting of water masses resulting from the regressive process on the northern and southern margins. Comparison between the main stages of transgression and regression allows some quantification concerning velocities of displacement of coastlines, specifically lengthwise. The permanence of paleogeographic and structural features over the time argues for an indisputable tectonic heritage. In the dynamic framework of this typical barred retroarc basin where arc magmatic activity has contributed considerably to variation on sediment supply and changing bathymetry of the seaways connecting with the Pacific Ocean, evidence for an assumed global eustatic cycle remains questionable or very subordinated.

  9. Jurassic Tectonic Revolution in China and New Interpretation of the "Yanshan Movement"

    Institute of Scientific and Technical Information of China (English)

    DONG Shuwen; ZHANG Yueqiao; LONG Changxing; YANG Zhenyu; JI Qiang; WANG Tao; HU Jianming; CHEN Xuanhua

    2008-01-01

    With acquisition and accumulation of new data of structural geological investigations and high-resolution isotopic dating data, we have greatly improved our understanding of the tectonic events occurring in eastern China during the period from the Late Jurassic to Early Cretaceous and may give a new interpretation of the nature, timing and geodynamic settings of the "Yanshan Movement". During the Mid-Late Jurassic (165±5 Ma), great readjustment of plate amalgamation kinematics took place in East Asia and the tectonic regime underwent great transformation, thus initiating a new tectonic regime in which the North China Block was the center and different plates converged toward it from the north, east and southwest and forming the "East Asia convergent"tectonic system characterized by intracontinental subduction and orogeny. As a consequence, the crustal lithosphere of the East Asian continent thickened considerably during the Late Jurassic,followed immediately by Early Cretaceous substantial lithospheric thinning and craton destruction featured by drastic lithospheric extension and widespread volcano-magmatic activities, resulting in a major biotic turnover from the Yanliao biota to Jehol Biota. Such a tremendous tectonic event that took place in the continent of China and East Asia is the basic connotation of the "Yanshan Movement". In the paper, according to the deformation patterns, geodynamic settings and deep processes, the "Yanshan Movement" is redefined as the Late Jurassic East Asian multi-directional plate convergent tectonic regime and its associated extensive intracontinental orogeny and great tectonic change that started at ~165±5 Ma. The substantial lithospheric attenuation in East China is considered the post-effect of the Yanshanian intracontinental orogeny and deformation.

  10. THE PROTECTION OF JURASSIC SITES AND FOSSILS: CHALLENGES FOR GLOBAL JURASSIC SCIENCE (INCLUDING A PROPOSED STATEMENT ON THE CONSERVATION OF PALAEONTOLOGICAL HERITAGE AND STRATOTYPES

    Directory of Open Access Journals (Sweden)

    KEVIN N. PAGE

    2004-03-01

    Full Text Available Effective geoconservation systems are crucial to the activities of subcommissions of the International Subcommission on Stratigraphy, such as the Jurassic Subcommission (ISJS. Fundamentally, the core activity of any Subcommission, the establishment of Global Stratotype Sections and Points (GSSPs is a conservation activity in itself, involving the selection of key sites, to be maintained as references for subsequent consultation. Without adequate national site protection and management systems this fundamental function is liable to fail as the selected site remains vulnerable to loss and damage. In addition, strict conservation systems applied without adequate understanding of the needs of research and education can also prevent or significantly inhibit geological science and the use of sites such as GSSPs. To address these extreme scenarios and assist the development of a more scientific approach to conservation of geological sites of stratigraphical and palaeontological importance during dialogues with administrative authorities, a Statement defining categories of palaeontological heritage requiring protection and the basic requirements needed to achieve the conservation of stratotype localities is here proposed. The context of the protection of Jurassic sites within other international projects is also reviewed, in particular the IUGS Geosites project, within which all GSSPs will be listed.

  11. Floral changes across the Triassic/Jurassic boundary linked to flood basalt volcanism

    Science.gov (United States)

    van de Schootbrugge, B.; Quan, T. M.; Lindström, S.; Püttmann, W.; Heunisch, C.; Pross, J.; Fiebig, J.; Petschick, R.; Röhling, H.-G.; Richoz, S.; Rosenthal, Y.; Falkowski, P. G.

    2009-08-01

    One of the five largest mass extinctions of the past 600million years occurred at the boundary of the Triassic and Jurassic periods, 201.6million years ago. The loss of marine biodiversity at the time has been linked to extreme greenhouse warming, triggered by the release of carbon dioxide from flood basalt volcanism in the central Atlantic Ocean. In contrast, the biotic turnover in terrestrial ecosystems is not well understood, and cannot be readily reconciled with the effects of massive volcanism. Here we present pollen, spore and geochemical analyses across the Triassic/Jurassic boundary from three drill cores from Germany and Sweden. We show that gymnosperm forests in northwest Europe were transiently replaced by fern and fern-associated vegetation, a pioneer assemblage commonly found in disturbed ecosystems. The Triassic/Jurassic boundary is also marked by an enrichment of polycyclic aromatic hydrocarbons, which, in the absence of charcoal peaks, we interpret as an indication of incomplete combustion of organic matter by ascending flood basalt lava. We conclude that the terrestrial vegetation shift is so severe and wide ranging that it is unlikely to have been triggered by greenhouse warming alone. Instead, we suggest that the release of pollutants such as sulphur dioxide and toxic compounds such as the polycyclic aromatic hydrocarbons may have contributed to the extinction.

  12. New robertinid foraminifers from the Early Jurassic of Adnet, Austria and their evolutionary importance

    Directory of Open Access Journals (Sweden)

    Sylvain Rigaud

    2016-12-01

    Full Text Available New benthic multichambered foraminifers have been discovered in the Hettangian–Sinemurian of the Northern Calcareous Alps (Adnet, Salzburg, Austria. Originally aragonitic, these forms are completely recrystallized but the early impregnation of their tests by Fe-Mn solutions has, to some extent, allowed an indirect preservation of their primary structure. The most remarkably preserved specimens are found in close vicinity to the marmorea crust, a heavily mineralized multiphased hardground. We describe two new genera, Velleditsiella gen. nov., a microgastropod look-alike foraminifer, which includes the species V. felicitaszae gen. et sp. nov. and V. spinaferra gen. et sp. nov., and Rossanella gen. nov., the first known representative of the superfamily Conorboidoidea, which includes the species R. martinii gen. et sp. nov. Considering their structural and morphological characteristics, Velleditsiella and Rossanella phylogenetically derive from two distinct Triassic lineages, respectively the families Trochosiphoniidae and Variostomatidae. The discovery of diverse aragonitic assemblages in earliest Jurassic strata dismisses the long believed hypothesis that all Jurassic aragonitic multichambered foraminifers originated from a single Oberhauserellidae ancestor. It also supports a lower impact of the Triassic/Jurassic biotic crisis on the evolution of aragonitic foraminifers. Hypotheses for the short term and long term evolution of aragonitic multichambered foraminifers are discussed and new phyletic trees are proposed.

  13. Origination and death of petroleum systems along the Late Jurassic/Early Cretaceous northern Tethyan margin

    Energy Technology Data Exchange (ETDEWEB)

    Golonka, J. [Mobil Research and Development Corp., Dallas, TX (United States); Kiessling, W. [Erlangen-Nuernberg Univ., Erlangen (Germany). Inst. fuer Geologie und Mineralogie; Krobicki, M. [Academy of Mining and Metallurgy, Cracow (Poland). Inst. of Petroleum Engineering; Bocharova, N.Y. [Russian Academy of Sciences, Moscow (Russian Federation). Center for Program Studies

    1997-09-01

    Breakup of Pangea during Jurassic and Cretaceous times created a system of rifts along the northern Tethyan margin. Some of these rifts developed into oceanic basins while others developed on continental crust and turned into aulacogenes. The basins were separated from the main Tethys ocean by several plates and ridges. Partial uplift of the main European plate and late Kimmerian orogeny resulted in the establishment of restricted conditions in the marginal Tethyan basins. The paleogeographic and paleoclimatic setting favoured upwelling along the ridges and continental margins. Source rock prediction value modelling placed Tethyan marginal basins among the best Jurassic source rocks of the world. Self-contained petroleum systems consisting of source rocks, carbonate reservoirs and evaporitic seals occur in the area east of Poland. Actual hydrocarbon production is ongoing in Afghanistan and the Amu-Daria province. Some of Carpathian oils might also be sourced by Late Jurassic/Early Cretaceous rocks. In the western area, petroleum systems were destroyed during the Alpine orogeny.

  14. Storms and tsunamis: evidence of event sedimentation in the Late Jurassic Tendaguru Beds of southeastern Tanzania

    Science.gov (United States)

    Bussert, Robert; Aberhan, Martin

    2004-06-01

    In Late Jurassic shallow marine siliciclastic sediments of the dinosaur-bearing Tendaguru Beds from the Mandawa Basin of southeastern Tanzania we identified several event deposits. Based on an analysis of their sedimentological and palaeontological features, a storm-induced origin can be assumed for the majority of these deposits. This interpretation is in agreement with the regional palaeogeography and palaeoclimatological data, and is further supported by the widespread evidence of Late Jurassic storm-controlled sedimentation in adjacent basins along the East African margin. A particularly striking feature is a laterally extensive, conglomeratic bed with gravel components up to 30 cm in diameter, and megaripples indicating southward transport directions. The troughs between ripples are filled by cross-bedded fine-grained sandstones and siltsones with inferred transport directions to the north. Giant bedforms, a mixture of clasts of marine and continental origin, and evidence of opposite current directions suggest that this chaotically deposited sediment may have formed from a tsunami. Within the available time resolution this event is synchronous with the Morokweng impact structure in South Africa. However, because of the considerable distance of Morokweng from the Jurassic sea, direct links between both events cannot be established. Alternative mechanisms such as a landslide-generated tsunami are plausible, but not yet supported by geophysical data.

  15. A new Basal sauropodomorph dinosaur from the Lower Jurassic Navajo sandstone of Southern Utah.

    Directory of Open Access Journals (Sweden)

    Joseph J W Sertich

    Full Text Available BACKGROUND: Basal sauropodomorphs, or 'prosauropods,' are a globally widespread paraphyletic assemblage of terrestrial herbivorous dinosaurs from the Late Triassic and Early Jurassic. In contrast to several other landmasses, the North American record of sauropodomorphs during this time interval remains sparse, limited to Early Jurassic occurrences of a single well-known taxon from eastern North America and several fragmentary specimens from western North America. METHODOLOGY/PRINCIPAL FINDINGS: On the basis of a partial skeleton, we describe here a new basal sauropodomorph dinosaur from the Lower Jurassic Navajo Sandstone of southern Utah, Seitaad ruessi gen. et sp. nov. The partially articulated skeleton of Seitaad was likely buried post-mortem in the base of a collapsed dune foreset. The new taxon is characterized by a plate-like medial process of the scapula, a prominent proximal expansion of the deltopectoral crest of the humerus, a strongly inclined distal articular surface of the radius, and a proximally and laterally hypertrophied proximal metacarpal I. CONCLUSIONS/SIGNIFICANCE: Phylogenetic analysis recovers Seitaad as a derived basal sauropodomorph closely related to plateosaurid or massospondylid 'prosauropods' and its presence in western North America is not unexpected for a member of this highly cosmopolitan clade. This occurrence represents one of the most complete vertebrate body fossil specimens yet recovered from the Navajo Sandstone and one of the few basal sauropodomorph taxa currently known from North America.

  16. Triassic-Jurassic organic carbon isotope stratigraphy of key sections in the western Tethys realm (Austria)

    Science.gov (United States)

    Ruhl, Micha; Kürschner, Wolfram M.; Krystyn, Leopold

    2009-05-01

    The late Triassic period is recognized as one of the five major mass extinctions in the fossil record. All these important intervals in earth history are associated with excursions in C-isotope records thought to have been caused by perturbations in the global carbon cycle. The nature and causes of C-isotopic events across the Triassic-Jurassic (T-J) transition however, are poorly understood. We present several new high resolution organic C-isotope records from the Eiberg Basin, Austria, including the proposed Global boundary Stratotype Section and Point (GSSP) for the base of the Jurassic. The Triassic-Jurassic boundary interval in these records is characterized by the initial and main negative organic carbon isotope excursions (CIE) of up to 8‰. The initial and main CIEs are biostratigraphically constrained by first and last occurrences of boundary defining macro- and microfossils (e.g. ammonites). High resolution C-isotope records appear to be an excellent correlation proxy for this period in the Eiberg Basin. Pyrolysis analysis demonstrates increased Hydrogen Index (HI) values for organic matter coinciding with the initial CIE. Terrestrial organic matter influx and mass occurrences of green algae remains may have influenced the C-isotope composition of the sedimentary organic matter. This may have contributed to the extreme amplitude of the initial CIE in the Eiberg Basin.

  17. Timing, duration, and causes for Late Jurassic-Early Cretaceous anoxia in the Barents Sea

    Science.gov (United States)

    Georgiev, Svetoslav V.; Stein, Holly J.; Hannah, Judith L.; Xu, Guangping; Bingen, Bernard; Weiss, Hermann M.

    2017-03-01

    Re-Os isochron ages for black shales of the Hekkingen Formation in the Barents Sea constrain the onset (157.7 ± 1.3 Ma) and termination (138.8 ± 1.0 Ma), and thereby indicate a long duration (∼19 Myr) of widespread Jurassic-Cretaceous anoxia in the Arctic. Integration of these new Re-Os ages with published radiometric ages, ammonite biostratigraphy and geomagnetic polarity chrons shows shorter late Oxfordian-late Kimmeridgian and longer Berriasian stages relative to estimates in the 2012 and 2016 Geological Time Scales. Late Jurassic anoxia was likely the result of warming climate due to high atmospheric CO2 levels from increased oceanic crust production. Rising temperatures enhanced weathering and nutrient supply, increased productivity, and slowed ocean circulation before a sea-level rise brought anoxic waters onto continental shelves. Assessment of new and published Os- and Sr-isotopic data suggests that prolonged oceanic anoxia required a sustained CO2 source from fast spreading rates and/or longer subduction zones and spreading ridges to balance large burial of carbon in voluminous Upper Jurassic and Lower Cretaceous black shales.

  18. Registro fósil y distribución de Anadenathera en Argentina desde el Mioceno hasta la actualidad

    Directory of Open Access Journals (Sweden)

    Fernández-Pacella, L.

    2015-06-01

    Full Text Available Currently Fabaceae, is one of the dominant families of the Seasonally Dry Tropical Forests or Neotropical seasonal dry forests. Anadenanthera which integrates the family, has wide geographical distribution in South America and the West Indies, but in Argentina it`s only present Anadenantera colubrina var. cebil in the north and their records are represented from the Miocene to the present through palynomorphs and mineralized woods. The main objective of this work is to contribute to the understanding in the context of the history of Anadenanthera during the Neogene and Quaternary in Argentina, on the basis of the review and integration of the paleobotanical history, geological and climatic available that have affected the genre in the country. Studied fossil materials come from different geological formations of Argentina: Chenque Formation (Miocene, Paraná Formation (Middle Miocene, San José Formation (Middle Miocene, Ituzaingó Formation (Pliocene and Iberá (Holocene. The material found on the Chenque Formation is referred to Polyadopollenites coincides with the described material for the Middle Miocene of the central-eastern Argentina and the Pliocene of northeast Argentina. On the other hand in Paraná and Ituzaingó Formation studied sample of mineralized woods of Anadenantheroxylon villaurquisense, finally the sample found in Holocene of Iberá Corrientes Province corresponds to Anadenanthera colubrina var. macrocarpa. With these data it can be concluded that Anadenathera had a wide geographical record in Miocene and Holocene of Argentina, it was found in sediments from the lower Miocene of Patagonia by integrating a Subtropical Paleoflora. From the Middle-Upper Miocene integrated the vegetation in northeast Argentine constituting xerophiles forests. Their last record is equivalent to the Middle Holocene of sediments from Ibera integrating the regional vegetation and indicating an open vegetation characteristics of dry environments

  19. Secular environmental precursors to Early Toarcian (Jurassic) extreme climate changes

    Science.gov (United States)

    Suan, Guillaume; Mattioli, Emanuela; Pittet, Bernard; Lécuyer, Christophe; Suchéras-Marx, Baptiste; Duarte, Luís Vítor; Philippe, Marc; Reggiani, Letizia; Martineau, François

    2010-02-01

    The Early Toarcian Oceanic Anoxic Event (T-OAE), about 183 myr ago, was a global event of environmental and carbon cycle perturbations, which deeply affected both marine biota and carbonate production. Nevertheless, the long-term environmental conditions prevailing prior to the main phase of marine extinction and carbonate production crisis remain poorly understood. Here we present a ˜ 8 myr-long record of Early Pliensbachian-Middle Toarcian environmental changes from the Lusitanian Basin, Portugal, in order to address the long-term paleoclimatic evolution that ultimately led to carbonate production and biotic crises during the T-OAE. Paleotemperature estimates derived from the oxygen isotope compositions of well-preserved brachiopod shells from two different sections reveal a pronounced ˜ 5 °C cooling in the Late Pliensbachian ( margaritatus- spinatum ammonite Zones boundary). This cooling event is followed by a marked ˜ 7-10 °C seawater warming in the Early Toarcian that, after a second cooling event in the mid- polymorphum Zone, culminates during the T-OAE. Calcium carbonate (CaCO 3) contents, the amount of nannofossil calcite and the mean size of the major pelagic carbonate producer Schizosphaerella, all largely covary with paleotemperatures, indicating a coupling between climatic conditions and both pelagic and neritic CaCO 3 production. Furthermore, the cooling and warming episodes coincided with major marine regressions and transgressions, respectively, suggesting that the growth and decay of ice caps may have exerted a strong control on sea-level fluctuations throughout the studied time interval. This revised chronology of environmental changes shows important similarities with Neogene and Paleozoic episodes of deglacial black shale formation, and thus prompts the reevaluation of ice sheet dynamics as a possible agent of Mesozoic events of extinction and organic-rich sedimentation.

  20. China Looks to Argentina to Grow Food

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    @@ It might sound perverse for a Chinese company to go halfway round the globe to grow soya and other crops on unproductive land in a dry corner of Argentina. Yet that is what Beidahuang Group, a state-owned farm company based in the north-eastern Chinese province of Heilongjiang, is doing in the Pa-tagonian province of Rio Negro.

  1. Education Reform Brings New Challenges to Argentina.

    Science.gov (United States)

    Rossetti, Mercedes

    1997-01-01

    A description of recent changes in Argentina's system of education looks at underlying policy, the redesigned schooling system, emphasis placed on English language instruction, the teacher training system, and problems in the process for assuring an adequate flow of qualified English teachers. (MSE)

  2. MASTER: bright PSN discovered in Argentina

    Science.gov (United States)

    Shumkov, V.; Lipunov, V.; Podesta, R.; Levato, H.; Buckley, D.; Gorbovskoy, E.; Tiurina, N.; Balanutsa, P.; Kuznetsov, A.; Vladimirov, V.; Gress, O.; Ivanov, K.; Chazov, V.; Lopez, C.; Podesta, F.; Saffe, C.; Pogrosheva, T.; Shurpakov, S.

    2016-10-01

    MASTER-OAFA (located in Argentina) auto-detection system ( Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L ) discovered OT source at (RA, Dec) = 22h 01m 01.36s -40d 15m 26.7s on 2016-10-31.08091 UT. The OT unfiltered magnitude is 16.9m (mlim=19.9m).

  3. Argentina and Brazil's Relations to the EU

    DEFF Research Database (Denmark)

    Christensen, Steen Fryba

    Analysen diskuterer Argentina og Brasiliens relationer til EU i nyere tid med udgangspunkt i forhandlingerne om en associeringsaftale mellem EU og Mercosur, der igangsattes efter underskrivelsen af en bi-regional rammeaftale i 1995. Fokus er i særlig grad på, hvordan disse relationer bedst forstås...

  4. Argentina : trade patterns and challenges ahead

    OpenAIRE

    Anos-Casero, Paloma; Rollo, Valentina

    2010-01-01

    Argentinean export growth was impressive during the recent economic boom (2003-2007). However, decomposing export growth reveals that the extensive margin (increases in exports of existing products to existing markets) dominates, while the intensive margin (increases in exports of new products or new markets) contributes little to export growth. Argentina's trade product concentration has ...

  5. Contact dermatitis caused by dimethylfumarate in Argentina.

    Science.gov (United States)

    Lo Balbo, A; Gotelli, M J; Mac Cormack, W P; Kogan, N; Gotelli, C

    2011-07-01

    For the first time in Argentina, we describe an outbreak of contact dermatitis. New pairs of shoes caused intense pruritus, pain, and eruption, followed by edema, blisters, and a severe negative impact on the epidermal barrier of the feet. We identify dimethylfumarate as the causal agent and suggest an analytical method for its fast identification.

  6. Registration of veterinary products in Argentina.

    Science.gov (United States)

    Butler, E; Cané, B G

    1995-12-01

    A scheme for registering pharmaceutical and biological products for veterinary use was introduced in Argentina in 1994, as part of a joint scheme for countries of the Common Market of the South (Mercado Común del Sur: "Mercosur'). The authors describe the main features of these regulations, and the process which led to their development.

  7. [Smoking during pregnancy in Argentina and Uruguay].

    Science.gov (United States)

    Althabe, Fernando; Colomar, Mercedes; Gibbons, Luz; Belizán, José M; Buekens, Pierre

    2008-01-01

    Argentina and Uruguay are among the countries in which a large proportion of young women smoke. The rate of smokers during pregnancy in both countries is not well known, and data on the characteristics of women who quit smoking during pregnancy compared to those who continue smoking are not available. We conducted a survey including 1512 pregnant women > or = 18 years old (796 in Argentina; 716 in Uruguay), during antenatal visits in public hospitals of large urban regions; 44% of the women in Argentina and 53% in Uruguay had been or were regular smokers. 11% of the surveyed women in Argentina and 18% in Uruguay continued smoking during pregnancy. In both countries, the proportion of women who lived with smokers, allowed smoking at home, and were regularly or always exposed to tobacco smoke indoors, were 49%, 46% and 20% in the subgroup of women who never smoked, 67%, 60% and 32% in those who quit, and 78%, 75% and 52% in those who continued smoking, respectively. The study confirms a serious public health problem in both countries, and documents that environmental exposure persists in subgroups of women, even in those who quit smoking. It is important that the public health sector should provide access to effective programs for smoking cessation, to women who smoke during pregnancy. For the development of a new program, any intervention intending to have at least a moderate and sustainable success, it should seriously consider including components targeting the smoking environment of the pregnant women who smoke.

  8. Fostering a Middle Class

    Institute of Scientific and Technical Information of China (English)

    YAO BIN

    2011-01-01

    Though there is no official definition of "middle class" in China,the tag has become one few Chinese people believe they deserve anyway.In early August,the Chinese Academy of Social Sciences released a report on China's urban development,saying China had a middle-class population of 230 million in 2009,or 37 percent of its urban residents.It also forecast half of city dwellers in China would be part of the middle class by 2023.

  9. Beijing Tibet Middle School

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The year marks the 20th anniversary of the Central Government decision to run Tibet middle schools in the hinterland. At present, there are such schools or Tibetan classes in 26 provinces and municipalities directly under the Central Government. They work to train technical personnel and teachers for Tibet. Launched in 1987, the Beijing Tibet Middle School has since trained more than 2,800 middle and high school students for Tibet. Many of them returned to Tibet for construction.

  10. Origin of intraformational folds in the Jurassic Todilto Limestone, Ambrosia Lake uranium mining district, McKinley and Valencia counties, New Mexico

    Science.gov (United States)

    Green, M.W.

    1982-01-01

    The Todilto Limestone of Middle Jurassic age in the Ambrosia Lake uranium mining district of McKinley and Valencia Counties, New Mexico, is the host formation for numerous small- to medium-sized uranium deposits in joints, shear zones, and fractures within small- to large-scale intraformational folds. The folds probably were formed as a result of differential sediment loading when eolian sand dunes of the overlying Summerville Formation of Middle Jurassic age migrated over soft, chemically precipitated, lime muds of the Todilto shortly after their deposition in a regressive, mixed fresh and saline lacustrine or marine environment of deposition. Encroachment of Summerville eolian dunes over soft Todilto lime muds was apparently a local phenomenon and was restricted to postulated beltlike zones which trended radially across the Todilto coastline toward the receding body of water. Intraformational folding is believed to be confined to the pathways of individual eolian dunes or clusters of dunes within the dune belts. During the process of sediment loading by migrating sand dunes, layers of Todilto lime mud were differentially compacted, contorted, and dewatered, producing both small- and large-scale plastic deformation structures, including convolute laminations, mounds, rolls, folds, and small anticlines and synclines. With continued compaction and dewatering, the mud, in localized areas, reached a point of desaturation at which sediment plasticity was lost. Prolonged loading by overlying dune sands thus caused faulting, shearing, fracturing, and jointing of contorted limestone beds. These areas or zones of deformation within the limestone became the preferred sites of epigenetic uranium mineralization because of the induced transmissivity created by sediment rupture. Along most of the prograding Todilto coastline, adjacent to the eolian dune belts, both interdune and coastal sabkha environments dominated during Todilto-Summerville time. Sediments in coastal areas

  11. A new basal sauropodomorph (Dinosauria: Saurischia from Quebrada del Barro Formation (Marayes-El Carrizal Basin, northwestern Argentina.

    Directory of Open Access Journals (Sweden)

    Cecilia Apaldetti

    Full Text Available BACKGROUND: Argentinean basal sauropodomorphs are known by several specimens from different basins; Ischigualasto, El Tranquilo, and Mogna. The Argentinean record is diverse and includes some of the most primitive known sauropodomorphs such as Panphagia and Chromogisaurus, as well as more derived forms, including several massospondylids. Until now, the Massospondylidae were the group of basal sauropodomorphs most widely spread around Pangea with a record in almost all continents, mostly from the southern hemisphere, including the only record from Antarctica. METHODOLOGY/PRINCIPAL FINDING: We describe here a new basal sauropodomorph, Leyesaurus marayensis gen. et sp. nov., from the Quebrada del Barro Formation, an Upper Triassic-Lower Jurassic unit that crops out in northwestern Argentina. The new taxon is represented by a partial articulated skeleton that includes the skull, vertebral column, scapular and pelvic girdles, and hindlimb. Leyesaurus is diagnosed by a set of unique features, such as a sharply acute angle (50 degrees formed by the ascending process of the maxilla and the alveolar margin, a straight ascending process of the maxilla with a longitudinal ridge on its lateral surface, noticeably bulging labial side of the maxillary teeth, greatly elongated cervical vertebrae, and proximal articular surface of metatarsal III that is shelf-like and medially deflected. Phylogenetic analysis recovers Leyesaurus as a basal sauropodomorph, sister taxon of Adeopapposaurus within the Massospondylidae. Moreover, the results suggest that massospondylids achieved a higher diversity than previously thought. CONCLUSIONS/SIGNIFICANCE: Our phylogenetic results differ with respect to previous analyses by rejecting the massospondylid affinities of some taxa from the northern hemisphere (e.g., Seitaad, Sarahsaurus. As a result, the new taxon Leyesaurus, coupled with other recent discoveries, suggests that the diversity of massospondylids in the southern

  12. 陕西神木侏罗纪恐龙足迹的新发现及其地层学意义%NEW JURASSIC DINOSAUR FOOTPRINTS OF SHENMU COUNTY, SHAANXI PROVINCE, AND THEIR STRATIGRAPHIC SIGNIFICANCE

    Institute of Scientific and Technical Information of China (English)

    张玉光; 李建军; 胡松梅; 张笠夫; 刘迪

    2012-01-01

    Geological and archeological survey in recent years has recovered a large number of dinosaur footprint fossils near two villages of Langanbao, Shenmu County,Shaanxi Province. Fossil footprints of these two sites are not only abundant but also different from each other. There were also different previously fossil footprints in the Shenmu area. The fossiliferous strata at the two footprint sites are of Early Jurassic and Middle Jurassic age, older than strata containong previously reported footprints in the Shenmu area and other parts of Shaanxi Province.%在进行文物普查时于陕西神木县栏杆堡镇附近发现了大量恐龙足迹化石,而且足迹的种类也不尽相同,同以往该地发现的足迹类型相比、存在明显的区别。两处足迹化石点地层时代分属早侏罗世和中侏罗世,较之以前在该地和省内其他地方发现的足迹化石的时代要早很多。在对化石所在地层作对比的同时,对陕西神木的恐龙足迹化石分布展开了探讨。

  13. Sedimentological, climatic and environmental changes during the Early Jurassic (Hettangian-Pliensbachian) on the northern Tethyan margin (Switzerland)

    Science.gov (United States)

    Schöllhorn, Iris; Foellmi, Karl; adatte, Thierry

    2016-04-01

    The Early Jurassic interval witnessed different phases of paleoenvironmental change, starting with the end-Triassic mass extinction event, c. 201.4 Ma ago, which was marked by terrestrial ecosystem turnover, up to 50% loss in marine biodiversity and large turnovers in global geochemical cycles linked to the onset of Central Atlantic Magmatic Province volcanism (Raup et Sepkosky, 1982 ; Hesselbo et al., 2002 ; Deenen et al., 2010). This time interval saw equally a phase of major climate change near the Pliensbachian-Toarcian boundary, which was followed by the Early Toarcian oceanic anoxic episode (e.g., Suan et al., 2010). Previous studies mainly focused on these major and short-lived events, while the remaining intervals of the Early Jurassic received significantly less attention. Therefore, in this study, we examine the sedimentological, geochemical and environmental changes between these events on the northern Tethyan margin (Swiss Jura). With this purpose, a wide array of geochemical analyses (carbon isotope, Rock-Eval, phosphorus content, mineralogy, trace and major element content and clay analyses) and sedimentary observations has been performed on four sections and cores (Frick, Riniken, Pfaffnau and Kreuzlingen). We observed two depositional systems: (1) the Schambelen Member (lower Hettangian) and the Frick Mb. (middle Upper Sinemurian), which are characterised by organic-rich shales intercalated by tempestites; and (2) the Beggingen Member (Upper Hettangian to Lower Sinemurian) and the Grünscholz, Breitenmatt and Rietheim Members (upper Upper Sinemurian to Pliensbachian), which are composed of carbonates marked by the presence of hiati, condensed beds, phosphate- and fossil-rich strata, and erosional features, which testify to a dynamic environment characterised by overall low sediment-accumulation rates. The clay fraction, composed mainly of kaolinite, chlorite and illite, was controlled by various parameters. The rise of kaolinite in the Late

  14. THE STRATIGRAPHY OF THE UPPER BATHONIAN TO MIDDLE OXFORDIAN SUCESSION OF THE ARAGONESE BRANCH OF THE CORDILLERA IBÉRICA (SPAIN AND ITS EUROPEAN CONTEXT

    Directory of Open Access Journals (Sweden)

    KEVIN N. PAGE

    2004-03-01

    Full Text Available The Upper Bathonian-Middle Oxfordian succession of the Aragonese branch of the Cordillera Ibérica is one of the most completely developed in Europe and includes localities of international importance for Jurassic bio- and chronostratigraphy. Of particular importance are a potential stratotype for the Upper Bathonian of North West Europe and reference sections for a number of Submediterranean Province Middle Oxfordian biostratigraphic units. The intervening Callovian sequence, albeit locally strongly condensed, also includes faunas of key stratigraphical importance. The sequence of stratigraphically important ammonite faunas for this interval is here reviewed and placed in its European context.

  15. DEFINING THE MIDDLE CLASS

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Classifying the middle class remains controversial despite its alleged growth China’s cities housed more than 230 million middle-class residents in 2009 or 37 percent of the urban population,according to the 2011 Blue Book of Cities in China released on August 3.

  16. DEFINING THE MIDDLE CLASS

    Institute of Scientific and Technical Information of China (English)

    WANG HAIRONG

    2011-01-01

    China's cities housed more than 230 million middle-class residents in 2009ot 37 percent of the urban population,according to the 2011 Blue Book of Cities in China released on August 3.In China's main urban centers,Beijing and Shanghai,the middle class accounted for 46 percent and 38 percent,respectively,of the local population.

  17. Middle East Respiratory Syndrome

    Centers for Disease Control (CDC) Podcasts

    2014-07-07

    This podcast discusses Middle East Respiratory Syndrome, or MERS, a viral respiratory illness caused by Middle East Respiratory Syndrome Coronavirus—MERS-CoV.  Created: 7/7/2014 by National Center for Immunization and Respiratory Diseases (NCIRD).   Date Released: 7/7/2014.

  18. The Middle East.

    Science.gov (United States)

    Blouin, Virginia; And Others

    This sixth grade resource unit focuses on Middle East culture as seen through five areas of the social sciences: anthropology-sociology, geography, history, economics, and political science. Among objectives that the student is expected to achieve are the following: 1) given general information on the Middle East through the use of film, visuals,…

  19. Jurassic tetrapods and flora of Cañadón Asfalto Formation in Cerro Cóndor area, Chubut Province Flora y tetrápodos del Jurásico de la Formación Cañadón Asfalto en el área de Cerro Cóndor, provincia de Chubut

    OpenAIRE

    2008-01-01

    The plant and tetrapod fossil record of the Cañadón Asfalto Formation (Middle to Late Jurassic) found in Cerro Cóndor area (Chubut Province) is summarized here. The flora is dominated by conifers (Araucariaceae, Cupressaceae sensu lato) but also includes ferns and equisetaleans. The tetrapod fauna is composed of dinosaur taxa described in the 70's as well as other remains recently described and other vertebrate groups such as amphibians, turtles, and mammals. The amphibian remains have been i...

  20. Mineralogy and geochemistry of the Jurassic coals from the Gheshlagh mine, Eastern Alborz

    Directory of Open Access Journals (Sweden)

    Gholam Hossein Shamanian

    2015-10-01

    Full Text Available Introduction The Alborz structural zone in northern Iran is the host of a number of important coal deposits. The Gheshlagh coal mine is one of them, which is located 35 km southeast of Azadshahr. Coal bearing strata in the Gheshlagh mining district occur in the middle part of the Lower Jurassic Shemshak Formation which consists mainly of shales, siltstones and sandstones. The Geshlagh coals have a low sulfur content and a low ash yield. The ash content of coal and its geochemical character depends on the environment of deposition and subsequent geological history (Yazdi and Esmaeilnia, 2004. The purpose of this study was to investigate the texural and mineralogical characteristcs of the Ghashlagh coals and to identify the geochemistry of the major and trace elements and their relationship to specific mineralogical components. These results are necessary to improve the understanding of coal characterization and to relate the mineralogy of different materials to their potential for producing acidic or alkaline mine waters associated with mining and preparation processes. Materials and methods About 20 samples were collected from the main coal seams. These samples were taken from fresh faces of the mine to avoid weathered surfaces and get fresh samples. The petrography of the samples was carried out by the conventional microscopic methods at the Golestan University. Mineralogical analyses were done by a X-ray diffractometer equipped with a CuKα tube and monochrometer (XRD Philips PW 1800 at the Kansaran Binaloud Company. The coal samples were initially crushed to less than 200 μm and homogenized. Then, 50 g from each sample was heated to 525 oC according to the United States Geological Survey procedure(Bullock et al., 2002. The concentration of the major and trace elements in the resulting ash samples was determined using a wavelength Xray fluorescence spectrometer (XRF Philips PW1480 at the Kansaran Binaloud Company. Results The Coal

  1. Age and composition of meta-ophiolite from the Rhodope Middle Allochthon (Satovcha, Bulgaria): A test for the maximum-allochthony hypothesis of the Hellenides

    Science.gov (United States)

    Froitzheim, Nikolaus; Jahn-Awe, Silke; Frei, Dirk; Wainwright, Ashlea N.; Maas, Roland; Georgiev, Neven; Nagel, Thorsten J.; Pleuger, Jan

    2014-08-01

    The metamorphosed thrust stack of the Rhodopes comprises a level with ophiolites (Middle Allochthon) underlain and overlain by continent-derived allochthons. The Upper Allochthon represents the European margin, but the origin of the Lower Allochthon remains controversial, with suggestions that it may be derived from an inferred microcontinent (Drama) or from the margin of Adria. Trace element compositions and Sr and Nd isotope ratios of metagabbroic amphibolites and enclosed meta-plagiogranites from the Satovcha Ophiolite, Middle Allochthon, show that they are cogenetic and represent suprasubduction zone ophiolites. U-Pb dating using laser ablation sector field inductively coupled plasma mass spectrometry of zircons from two meta-plagiogranites and a metagabbro yielded identical Jurassic ages (160 ± 1 Ma, 160.6 ± 1.8 Ma, and 160 ± 1 Ma, respectively), similar to ophiolites in the eastern Vardar Zone bordering the Rhodopes to the SW. The trace element patterns also closely resemble those of the Vardar ophiolites. The association with Late Jurassic arc-type granitoids is another feature that applies both to eastern Vardar and Satovcha. This strongly suggests that the Middle Allochthon comprises the metamorphosed northeastward continuation of the Vardar Zone. The Jurassic age of the Satovcha Ophiolite contradicts the hypothesis of Early Jurassic suturing between Europe (Upper Allochthon) and the assumed Drama microcontinent (Lower Allochthon) but is in line with the "maximum allochthony hypothesis," i.e., the assumption that the Lower Allochthon represents Adria and that the "root" of the Vardar-derived thrust sheets is at the NE boundary of the Rhodopes.

  2. Palaeoclimatic conditions in the Late Triassic-Early Jurassic of southern Africa: A geochemical assessment of the Elliot Formation

    Science.gov (United States)

    Sciscio, Lara; Bordy, Emese M.

    2016-07-01

    The Triassic-Jurassic boundary marks a global faunal turnover event that is generally considered as the third largest of five major biological crises in the Phanerozoic geological record of Earth. Determining the controlling factors of this event and their relative contributions to the biotic turnover associated with it is on-going globally. The Upper Triassic and Lower Jurassic rock record of southern Africa presents a unique opportunity for better constraining how and why the biosphere was affected at this time not only because the succession is richly fossiliferous, but also because it contains important palaeoenvironmental clues. Using mainly sedimentary geochemical proxies (i.e., major, trace and rare earth elements), our study is the first quantitative assessment of the palaeoclimatic conditions during the deposition of the Elliot Formation, a continental red bed succession that straddles the Triassic-Jurassic boundary in southern Africa. Employing clay mineralogy as well as the indices of chemical alteration and compositional variability, our results confirm earlier qualitative sedimentological studies and indicate that the deposition of the Upper Triassic and Lower Jurassic Elliot Formation occurred under increasingly dry environmental conditions that inhibited chemical weathering in this southern part of Pangea. Moreover, the study questions the universal validity of those studies that suggest a sudden increase in humidity for the Lower Jurassic record and supports predictions of long-term global warming after continental flood basalt emplacement.

  3. A Peculiar New Pampatheriidae (Mammalia: Xenarthra: Cingulata) from the Pleistocene of Argentina and Comments on Pampatheriidae Diversity

    Science.gov (United States)

    Scillato-Yané, Gustavo Juan; Soibelzon, Esteban

    2015-01-01

    Pampatheriidae are a group of cingulates native to South American that are known from the middle Miocene to the lower Holocene. Two genera have been recognized between the lower Pleistocene and the lower Holocene: Pampatherium Gervais and Ameghino (Ensenadan, Bonaerian and Lujanian, lower Pleistocene–lower Holocene) and Holmesina Simpson (Blancan, Irvingtonian, upper Pliocene–lower Holocene). They have been mainly differentiated by their osteoderm morphology and cranio-dental characters. These taxa had a wide latitudinal distribution, extending from the southern part of South America (Península Valdés, Argentina) to North America (Florida, USA). In this contribution, we describe a new genus and species of Pampatheriidae for the lower and middle Pleistocene of Buenos Aires Province and for the upper Pleistocene of Santa Fe Province (Argentina).The new taxon is represented by disarticulated osteoderms, one skull element, two thoracic vertebrae and a right femur and patella. It has extremely complex osteoderm ornamentations and particular morphological characters of the cranial element and femur that are not found in any other species of the family. This new taxon, recorded in the lower–middle Pleistocene (Ensenadan Stage/Age) and in the upper Pleistocene–early Holocene (Lujanian Stage/Age), is incorporated to the Pleistocene mammal assemblage of South America. Finally, the Pampatheriidae diversity is greater during the Lujanian Stage/Age than the Ensenadan Stage/Age. PMID:26083486

  4. La migracion internacional en Argentina hacia 2010

    Directory of Open Access Journals (Sweden)

    Laura Calvelo

    Full Text Available El artículo presenta los principales lineamientos de la migración internacional en Argentina hacia el año 2010, con detenimiento en el período 2000-2010. En el caso de la inmigración no nativa se basa en información de los censos nacionales de población 2001 y 2010. En el caso de la migración internacional de la población nativa de Argentina el análisis se sustenta en información de censos extranjeros hasta la ronda 2000 y en otras fuentes de datos de los principales países de destino hasta 2010 (Estados Unidos y España.

  5. Vaccines in Argentina: a regulatory view.

    Science.gov (United States)

    Pérez, A C; Diez, R A

    2003-07-28

    In Argentina, vaccines for immuno-preventable diseases are regulated by the national regulatory agency, the Administración Nacional de Medicamentos, Alimentos y Tecnología Médica (the National Administration of Drugs, Food and Medical Devices, or ANMAT) created in 1992 to ensure efficacy and safety of drugs, food and medical devices available in the country, according to Law 16,463 and Decree 150/92. ANMAT has licensed 84 out of 157 vaccines registered in Argentina. Since 1994, ANMAT evaluated, approved and inspected 20 clinical trials with vaccines (1.8% of the 1062 trials approved by the agency since that time). The National System of Pharmaco-vigilance has received 318 communications of eventual adverse post-vaccination events (0.3% of the total). In addition, ANMAT provides support to the National Immunisation Programme. The current procedure is to follow international guidelines in the field, to be prepared for new, rapidly changing scenarios.

  6. MASTER: 2 OT discovered in Argentina

    Science.gov (United States)

    Shumkov, V.; Pogrosheva, T.; Lipunov, V.; Podesta, R.; Levato, H.; Gorbovskoy, E.; Tiurina, N.; Balanutsa, P.; Kuznetsov, A.; Vladimirov, V.; Gress, O.; Ivanov, K.; Chazov, V.; Lopez, C.; Podesta, F.; Saffe, C.

    2016-10-01

    MASTER-OAFA, located in Argentina, with auto-detection system (Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L) discovered OT source at (RA, Dec) = 03h 19m 42.92s -45d 30m 13.9s on 2016-10-27.27597 UT. The OT unfiltered magnitude is 16.9m (mlim=20.8m).

  7. ZANTHOXYLUM ARMATUM (RUTACEAE, SU PRESENCIA EN ARGENTINA

    Directory of Open Access Journals (Sweden)

    Marcelo D. Arana

    2009-01-01

    Full Text Available Se cita por primera vez a Zanthoxylum armatum var. armatum como especie asilvestrada para la flora argentina, en la provincia de Córdoba. Se presenta una descripción sobre la base de los ejemplares examinados, ilustraciones, mapa de distribución y observaciones ecológicas, como así también las diferencias con taxones similares.

  8. Journalism studies in Argentina: background and questions

    OpenAIRE

    Adriana Amado; Natalia Pizzolo

    2014-01-01

    This article summarizes the background of empirical journalism studies in Argentina.  In recent publications, researchers have consistently underscored the lack of data on the profession and the scarce development of theoretical frameworks related to journalism studies.  The local investigations have prioritized approaches and methods that do not give the whole picture of the population of journalists. Most of the research tends to equate media analysis and media messages with journalism stud...

  9. SMEs in Argentina: Who are the Exporters?

    OpenAIRE

    Ottaviano, Gianmarco I.P.; Martincus, Christian Volpe

    2009-01-01

    There exists a growing body of literature which looks at export decisions made by firms. Most studies focus on developed countries and do not explore whether different behavioral patterns prevail over the firm size distribution. This paper aims at filling this gap in the literature by analyzing the export behavior of a statistically representative sample of 192 Small and Medium-Size Enterprises (SMEs) in a developing country, Argentina, over the period 1996-1998. We find that the level of emp...

  10. La izquierda Argentina: nuevamente el fracaso

    Directory of Open Access Journals (Sweden)

    Ángel Rodríguez Kauth

    2004-01-01

    Full Text Available A partir de los acontecimientos políticos y sociales ocurridos en Argentina desde finales de 2001, se estudia el papel protagónico que tuvieron las diversas organizaciones en que se ha atomizado la izquierda vernácula. Esto es no sólo en el plano electoral, sino también en el de las movilizaciones junto a la participación popular que reclamaba su presencia.

  11. Sunflower crop in Argentina to date

    OpenAIRE

    Vasquez A.; de Romano A.

    2006-01-01

    Inside a panorama of a spectacular grain production in the last 10 years in Argentina, sunflower crop participates with an annual production of more than 3,500,000 t. During that period, many advances were made in the improvement of diseases resistance: Verticillium wilt, downy mildew and head rot. Also oil yield per hectare continued to increase. The new hybrids have new qualities, for example imidazolinones resistance, which allows farmers to keep yields, although the soils destined to sunf...

  12. Prospects for Corn Ethanol in Argentina

    OpenAIRE

    Bruce A. Babcock; Miguel Carriquiry

    2012-01-01

    Countries that export biofuel feedstocks such as grain or sugar and that are also importers of motor fuels will have a natural competitive advantage over other countries in the production of biofuels. Argentina is one of a very few countries that both export potential feedstocks and import gasoline and diesel. This combination means that an Argentine ethanol plant will pay less for feedstock and receive a higher price for ethanol than an ethanol plant located in a country that imports feedsto...

  13. Andes Altiplano, Northwest Argentina, South America

    Science.gov (United States)

    1993-01-01

    This view of the Andes Altiplano in northwest Argentina (25.5S, 68.0W) is dominated by heavily eroded older and inactive volcano peaks. The altiplano is a high altitude cold desert like the Tibetan Plateau but smaller in area. It is an inland extension of the hyperarid Atacama Desert of the west coast of South America and includes hundreds of volcanic edifices (peaks, cinder cones, lava flows, debris fields, lakes and dry lake beds (salars).

  14. On middle cube graphs

    Directory of Open Access Journals (Sweden)

    C. Dalfo

    2015-10-01

    Full Text Available We study a family of graphs related to the $n$-cube. The middle cube graph of parameter k is the subgraph of $Q_{2k-1}$ induced by the set of vertices whose binary representation has either $k-1$ or $k$ number of ones. The middle cube graphs can be obtained from the well-known odd graphs by doubling their vertex set. Here we study some of the properties of the middle cube graphs in the light of the theory of distance-regular graphs. In particular, we completely determine their spectra (eigenvalues and their multiplicities, and associated eigenvectors.

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

    Science.gov (United States)

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

    2008-01-01

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

  16. Hadley circulation and precipitation changes controling black shale deposition in the Late Jurassic Boreal Seaway

    Science.gov (United States)

    Armstrong, Howard A.; Wagner, Thomas; Herringshaw, Liam G.; Farnsworth, Alexander J.; Lunt, Daniel J.; Harland, Melise; Imber, Jonathan; Loptson, Claire; Atar, Elizabeth F. L.

    2016-08-01

    New climate simulations using the HadCM3L model with a paleogeography of the Late Jurassic (155.5 Ma) and proxy-data corroborate that warm and wet tropical-like conditions reached as far north as the UK sector of the Jurassic Boreal Seaway (~35°N). This is associated with a northern hemisphere Jurassic Hadley cell and an intensified subtropical jet which both extend significantly poleward than in the modern (July-September). Deposition of the Kimmeridge Clay Formation (KCF) occurred in the shallow, storm-dominated, epeiric Boreal Seaway. High-resolution paleo-environmental proxy data from the Kimmeridge Clay Formation (KCF; ~155-150 Ma), UK, are used to test for the role of tropical atmospheric circulation on meter-scale heterogeneities in black shale deposition. Proxy and model data show that the most organic-rich section (eudoxus to mid-hudlestoni zones) is characterized by a positive δ13Corg excursion and up to 37 wt % total organic carbon (%TOC). Orbital modulation of organic carbon burial primarily in the long eccentricity power band combined with a clear positive correlation between %TOC carbonate-free and the kaolinite/illite ratio supports peak organic carbon burial under the influence of very humid climate conditions, similar to the modern tropics. This reinterpretation of large-scale climate relationships, supported by independent modeling and geological data, has profound implications for atmospheric circulation patterns and processes affecting marine productivity and organic carbon burial further north along the Boreal Seaway, including the Arctic.

  17. On a pterosaur jaw from the Upper Jurassic of Tendaguru (Tanzania

    Directory of Open Access Journals (Sweden)

    D. M. Unwin

    1999-01-01

    Full Text Available A short section of a mandibular symphysis is the first cranial fossil of a pterosaur to be reported from the Upper Jurassic of Tendaguru, Tanzania. It is made the holotype of a new dsungaripteroid pterosaur, Tendaguripterus recki n. gen. n. sp. All previously named pterosaur taxa from Tendaguru are shown to be nomina dubia. The pterosaur assemblage from Tendaguru contains a "rhamphorhynchoid", as well as the dsungaripteroid, and is similar in its systematic composition to other Late Jurassic pterosaur assemblages from Laurasia. The diversity and broad distribution of dsungaripteroids in the Late Jurassic suggests that the group was already well established by this time. Der erste Schädelrest eines Flugsauriers aus dem Oberjura von Tendaguru in Tansania wird beschrieben. Bei dem Fundstück handelt es sich um ein bezahntes Unterkieferbruchstück aus der Symphysenregion. Der Fund gehört zu einem neuen Taxon, das als Tendaguripterus recki n. gen. n. sp. bezeichnet und zur Überfamilie Dsungaripteroidea gestellt wird. Alle zuvor aus den Tendaguru-Schichten beschriebenen Taxa werden als nomina dubia angesehen. In Tendaguru sind Verteter der „Rhamphorhynchoidea“ und Dsungaripteroidea nachgewiesen. Diese systematische Zusammensetzung ist derjenigen anderer Flugsaurier-Vergesellschaftungen der späten Jura-Zeit ähnlich. Die Vielfalt und die weite Verbreitung der Dsungaripteroidea in Laurasia läßt darauf schließen, daß sich diese Flugsauriergruppe bereits in der späten Jura-Zeit erfolgreich durchgesetzt hatte. doi:10.1002/mmng.1999.4860020109

  18. Embryology of Early Jurassic dinosaur from China with evidence of preserved organic remains.

    Science.gov (United States)

    Reisz, Robert R; Huang, Timothy D; Roberts, Eric M; Peng, ShinRung; Sullivan, Corwin; Stein, Koen; LeBlanc, Aaron R H; Shieh, DarBin; Chang, RongSeng; Chiang, ChengCheng; Yang, Chuanwei; Zhong, Shiming

    2013-04-11

    Fossil dinosaur embryos are surprisingly rare, being almost entirely restricted to Upper Cretaceous strata that record the late stages of non-avian dinosaur evolution. Notable exceptions are the oldest known embryos from the Early Jurassic South African sauropodomorph Massospondylus and Late Jurassic embryos of a theropod from Portugal. The fact that dinosaur embryos are rare and typically enclosed in eggshells limits their availability for tissue and cellular level investigations of development. Consequently, little is known about growth patterns in dinosaur embryos, even though post-hatching ontogeny has been studied in several taxa. Here we report the discovery of an embryonic dinosaur bone bed from the Lower Jurassic of China, the oldest such occurrence in the fossil record. The embryos are similar in geological age to those of Massospondylus and are also assignable to a sauropodomorph dinosaur, probably Lufengosaurus. The preservation of numerous disarticulated skeletal elements and eggshells in this monotaxic bone bed, representing different stages of incubation and therefore derived from different nests, provides opportunities for new investigations of dinosaur embryology in a clade noted for gigantism. For example, comparisons among embryonic femora of different sizes and developmental stages reveal a consistently rapid rate of growth throughout development, possibly indicating that short incubation times were characteristic of sauropodomorphs. In addition, asymmetric radial growth of the femoral shaft and rapid expansion of the fourth trochanter suggest that embryonic muscle activation played an important role in the pre-hatching ontogeny of these dinosaurs. This discovery also provides the oldest evidence of in situ preservation of complex organic remains in a terrestrial vertebrate.

  19. Argentina: Nuclear power development and Atucha 2

    Energy Technology Data Exchange (ETDEWEB)

    Nogarin, Mauro

    2015-08-15

    In 2014, nuclear energy generated about 5,257 GWh of electricity or a total share of 4.05 % of the total electrical energy of about 129,747.63 GWh kWh produced in Argentina and there has been a trend for this production to increase. Argentina currently has a nuclear production capacity of 1,010 megawatts of electrical energy. However, when the Atucha 2 nuclear power plant is completed and starts commercial operation, it will add 745 megawatts to this electrical production capacity. There are two sites with nuclear power plants in Argentina: Atucha and Embalse. The Embalse nuclear power plant went into operation in 1984. At the Atucha site, the Atucha-1 nuclear power plant started operation in 1974. It was the first nuclear power plant in Latin America. Construction of Atucha-2 started in 1981 but advanced slowly due to funding and was suspended in 1994 when the plant was 81 % built. In 2003, new plans were approved to complete the Atucha 2. I summer 2014 the plant went critical for the first time. The construction was completed under a contract with AECL.

  20. The Case of Argentina, 1993-2000

    Directory of Open Access Journals (Sweden)

    Mario Tonveronachi

    2006-01-01

    Full Text Available El consenso sobre los beneficios netos de la presencia de bancos extranjeros en los países emergentes parece en alguna medida debilitarse a raíz de la experiencia de los años noventa, que constituye una fase de fuerte expansión y fortalecimiento de dicha presencia. Distinguiendo entre la presencia y la dominancia en el mercado local por parte de los bancos extranjeros, el presente trabajo analiza la experiencia argentina en el período 1993-2000. Para este fin, se reconstruyo por primera vez la serie completa de los balances bancarios. Los resultados sugieren que la aumentada presencia de bancos extranjeros no ha producido beneficios significativos, mientras que todo el sistema bancario se ha aventajado por el clima de mayor crecimiento y de estabilidad monetaria. Como parte de la estrategia perseguida por parte del poder público, la creciente dominancia de los bancos extranjeros resulta uno de los factores que han empobrecido la biodiversidad de la banca argentina. De todos modos, parte de los problemas que atormentaron a la economía argentina en los años noventa podrían ser considerados más como el resultado de la adopción de una abertura financiera completa que como consecuencia de la dominancia creciente por parte de los bancos extranjeros.

  1. Oldest isotopically characterized fish otoliths provide insight to Jurassic continental climate of Europe

    Science.gov (United States)

    Patterson, William P.

    1999-03-01

    Large, shallow, epeiric seas and adjacent lagoons such as those described herein likely played a significant role in moderating Jurassic coastal and continental climate. Jurassic (Bathonian) ocean surface temperatures in Scotland have been calculated from δ18O(CaCO3) values of a suite of the oldest well-preserved fish otoliths analyzed to date. Otolith δ18O values range from -4.7‰ to -1.9‰ (Vienna Peedee belemnite, VPDB), while δ13C(CaCO3) values vary from -5.4‰ to +1.5‰ (VPDB), representing the oldest stable isotopic record of paleodiet, paleoecology, and fish migration to date. Using a global ocean δ18O(H2O) value of -1.0‰ (Vienna standard mean ocean water, VSMOW) for an ice-free Jurassic, fish species that migrated from estuarine to open marine water record time-averaged temperatures of 23 °C. Estuarine fish, assuming a similar temperature, record variation in δ18O(H2O) values from -3.7‰ to -2.0‰ (VSMOW). That significant mixing of fresh water and seawater occurred in the Jurassic in Scotland is in general agreement with data presented by others (molluscan fauna, lithostratigraphy, paleogeography, and paleocirculation models). The δ18O values and temperatures derived in this study correspond to the meteorologic and hydrologic parameters of a mid-latitude maritime climate with low seasonality, a mean temperature of 23 °C, and abundant precipitation and humidity. The δ18O(H2O) values calculated from estuarine fish indicate that rainfall must have a δ18O(H2O) value lower than -3.7‰ (VSMOW). Values of δ18O and δ13C suggest an environment hydrologically similar to that observed in the Everglades of south Florida or the estuaries of south Texas, both notable fish nurseries today. However, sea-surface temperatures were lower than those of modern Florida or Texas as evidenced by reduced evaporative enrichment of δ18O(H2O) values.

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

    Science.gov (United States)

    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.

  3. Embryos of an early Jurassic prosauropod dinosaur and their evolutionary significance.

    Science.gov (United States)

    Reisz, Robert R; Scott, Diane; Sues, Hans-Dieter; Evans, David C; Raath, Michael A

    2005-07-29

    Articulated embryos from the Lower Jurassic Elliot Formation of South Africa are referable to the prosauropod Massospondylus carinatus and, together with other material, provide substantial insights into the ontogenetic development in this early dinosaur. The large forelimbs and head and the horizontally held neck indicate that the hatchlings were obligate quadrupeds. In contrast, adult Massospondylus were at least facultatively bipedal. This suggests that the quadrupedal gait of giant sauropods may have evolved by retardation of postnatal negative allometry of the forelimbs. Embryonic body proportions and an absence of well-developed teeth suggest that hatchlings of this dinosaur may have required parental care.

  4. LATE JURASSIC AND EARLY CRETACEOUS AMMONITES FROM THE WEIMEI FORMATION IN GYANGZE, SOUTHERN TIBET

    Directory of Open Access Journals (Sweden)

    MASAHIKO TAKEI

    2004-03-01

    Full Text Available The Weimei Formation in southern Tibet is a shallow marine sequence accumulated in the northern margin of the Indian subcontinent. It has been dated as Tithonian based on ammonites such as Haplophylloceras strigile (Blanford, Berriasella sp. and Himalayites sp. Six ammonite specimens were found in the type locality of the Weimei Formation. They include Spiticeras (Spiticeras spitiense (Blanford, Berriasella sp. and Phylloceras sp. The occurrence of S. spitiense indicates that the ammonite-bearing portion is assignable to the Berriasian stage. The Jurassic/Cretaceous boundary possibly exists within the Weimei Formation.

  5. Changes of taxonomical composition of Late Jurassic Early Cretaceous palynofloras of Bureya Basin,Russia

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The changes of taxonomical composition of the Late Jurassic-Early Cretaceous palynofloras are revealed,in the upper stream of Bureya River in Bureya Basin.The palynofloras are dominated as follows:the Berriasian one by ferns (Cyatheaceae,Dicksoniaceae,Osmundaceae), Classopollis and bisaccate pollen;the Valanginian-Hauterivian one by ferns (Cyatheaceae,Dicksoniaceae), Ginkgocycadophytus and bisaccate pollen;the Barremian one by ferns(Cyatheaceae,Dieksoniaceae);the Aptian one by ferns(Cyatheaceae,Dieksoniaceae,Gleicheniaceae)and Ginkgocycadophytus;and the Albian one by ferns(Schizaeaceae)and bisaccate pollen.In the Albian the floral diversity raises with the angiosperms appearing.

  6. Evidence for long term deep CO2 confinement below thick Jurassic shales at Montmiral site (SE Basin of France)

    Science.gov (United States)

    Rubert, Y.; Ramboz, C.; Le Nindre, Y. M.; Lerouge, C.; Lescanne, M.

    2009-04-01

    basement; - Middle unit: Triassic-Liassic reservoir; - Upper unit: late Jurassic to Cretaceous. The middle unit (reservoir) and the upper unit are separated by the thick, tight seal, Domerian to Oxfordian in age. The definition of these lithological units was made using combined petrographic techniques (cathodoluminescence CL, fluorescence, Raman spectroscopy, crushing tests), geochemical techniques (C and O isotopes) and microthermometry. Lower unit: Paleozoïc basement - In the metamorphic basement, aquo-carbonic and CO2-dominant fluids are trapped as primary fluid inclusions in hydrothermal barite and fluoroapatite, and as secondary fluid inclusions in extensionnal microcracks crosscutting metamorphic quartz. All these fluids, trapped in the two-phase stability field, indicate firstly a limited phase separation at 300°C and 400-500 bars evolving toward wider CO2-H2O unmixing at 200°C and 200 bars. Basinal saline brines (10 and 15-25 wt % eq. NaCl and 70data provide evidence for a first circulation of a moderate temperature (80°C) marine origin fluids equilibrated with surrounding rocks (Delta18O ~ 0,5 permil SMOW) and a late circulation of lower temperature (52°C) meteoric fluids also equilibrated with limestones (Delta18O ~ -7 permil SMOW). CO2 inclusions belong to the latest phase of fracturing, occurring during the meteoric fluids circulation phase. These open fractures, with dog-tooth style euhedral calcite, exhibit, by comparison with the outcrop, a fabric of typical Pyrenean type. Upper unit: late Jurassic to Cretaceous - Above the seal, the fractures are exclusively filled with carbonates (calcite and dolomite) trapping aqueous fluid inclusions only. CL, microthermometry and isotopic data provide evidence for low temperature meteoric fluids (Delta18O ~ -5 permil SMOW) with numerous karstic features in Cretaceous strata. In conclusion, the CO2 feeding phase occurred under high pressure conditions requiring the presence of a thick sedimentary cover. The cement

  7. The Global Boundary Stratotype Section and Point (GSSP) for the base of the Pliensbachian Stage (Lower Jurassic), Wine Haven, Yorkshire, UK

    Institute of Scientific and Technical Information of China (English)

    Christian Meister; Mark Hylton; Nicol Morton; Kevin Page; Greg D. Price; Martin Aberhan; Joachim Blau; Jean-Louis Dommergues; Susanne Feist-Burkhardt; Ernie A. Hailwood; Malcom Hart; Stephen P. Hesselbo; Mark W. Hounslow

    2006-01-01

    @@ Following votes by the Pliensbachian Working Group, the Jurassic Subcommission and the International Commission on Stratigraphy, IUGS ratified the proposed Global Boundary Stratotype Section and Point (GSSP) for the base of the Pliensbachian Stage (Lower Jurassic) at the base of bed 73b in the Wine Haven section, Robin Hood's Bay, Yorkshire Coast, UK.

  8. Reptiles escamosos (Squamata del Pleistoceno Medio del Norte de la ciudad de Mar del Plata (provincia de Buenos Aires, Argentina

    Directory of Open Access Journals (Sweden)

    Santiago Brizuela

    2015-05-01

    Full Text Available In this study, we describe two fossil remains of squamate reptiles found in Middle Pleistocene outcrops at the northern marine cliffs of the city of Mar del Plata (Buenos Aires province. The specimens were found forming a taphocenosis with remains of other microvertebrates (amphibians, mammals and birds. The reptiles recognized in the association are represented by remains of an undetermined colubrid, and the anguid Ophiodes sp. This latter finding represents the first fossil record for the family Anguidae exhumed in Argentina.

  9. Climatic fluctuations and seasonality during the Late Jurassic (Oxfordian-Early Kimmeridgian) inferred from δ18O of Paris Basin oyster shells

    Science.gov (United States)

    Brigaud, Benjamin; Pucéat, Emmanuelle; Pellenard, Pierre; Vincent, Benoît; Joachimski, Michael M.

    2008-08-01

    Oxygen isotope data from biostratigraphically well-dated oyster shells from the Late Jurassic of the eastern Paris Basin are used to reconstruct the thermal evolution of western Tethyan surface waters during the Early Oxfordian-Early Kimmeridgian interval. Seventy eight oyster shells were carefully screened for potential diagenetic alteration using cathodoluminescence microscopy. Isotope analyses were performed on non-luminescent parts of shells (n = 264). Intra-shell δ18O variability was estimated by microsampling along a transect perpendicular to the growth lines of the largest oyster shell. The sinusoidal distribution of the δ18O values along this transect and the dependence of the amplitude of variations with bathymetry suggest that intra-shell variability reflects seasonal variations of temperature and/or salinity. Average amplitudes of about 5 °C in shallow water environments and of about 2-3 °C in deeper offshore environments are calculated. These amplitudes reflect minimum seasonal temperature variation. Our new data allow to constrain existing paleotemperature trends established from fish tooth and belemnite δ18O data and are in better agreement with paleontological data. More specifically, a warming trend of about 3 °C is reconstructed for oceanic surface waters during the Early to Middle Oxfordian transition, with maximum temperatures reaching 24 °C in the transversarium Zone (late Middle Oxfordian). From the transversarium Zone to the bimmamatum Zone, a cooling of about 7 °C is indicated, whereas from the bimmamatum Zone, temperatures increased again by about 7 °C to reach 24 °C in average during the cymodoce Zone (Early Kimmeridgian).

  10. Structure of an inverted basin from subsurface and field data: the Late Jurassic-Early Cretaceous Maestrat Basin (Iberian Chain)

    Energy Technology Data Exchange (ETDEWEB)

    Nebot, M.; Guimera, J.

    2016-07-01

    The Maestrat Basin experienced two main rifting events: Late Permian-Late Triassic and Late Jurassic-Early Cretaceous, and was inverted during the Cenozoic Alpine orogeny. During the inversion, an E-W-trending, N-verging fold-and-thrust belt developed along its northern margin, detached in the Triassic evaporites, while southwards it also involved the Variscan basement. A structural study of the transition between these two areas is presented, using 2D seismic profiles, exploration wells and field data, to characterize its evolution during the Mesozoic extension and the Cenozoic contraction. The S-dipping Maestrat basement thrust traverses the Maestrat Basin from E to W; it is the result of the Cenozoic inversion of the lower segment–within the acoustic basement–of the Mesozoic extensional fault system that generated the Salzedella sub-basin. The syn-rift Lower Cretaceous rocks filling the Salzedella sub-basin thicken progressively northwards, from 350m to 1100m. During the inversion, a wide uplifted area –40km wide in the N-S direction– developed in the hanging wall of the Maestrat basement thrust. This uplifted area is limited to the North by the E-W-trending Calders monocline, whose limb is about 13km wide in its central part, dips about 5ºN, and generates a vertical tectonic step of 800-1200m. We interpreted the Calders monocline as a fault-bend fold; therefore, a flat-ramp-flat geometry is assumed in depth for the Maestrat basement thrust. The northern synformal hinge of the Calders monocline coincides with the transition from thick-skinned to thin-skinned areas. The vast uplifted area and the low-dip of the monocline suggest a very low-dip for the basement ramp, rooted in the upper crust. The Calders monocline narrows and disappears laterally, in coincidence with the outcrop of the Maestrat basement thrust. The evaporitic Middle Muschelkalk detachment conditioned the structural style. Salt structures are also related to it; they developed during the

  11. Jurassic (uppermost Sinemurian - Aalenian sequence stratigraphy and geodynamic evolution of the Ait Bou Guemmez area (Central High Atlas, Morocco

    Directory of Open Access Journals (Sweden)

    El Bchari, F.

    2008-12-01

    Full Text Available In the Ait Bou Guemmez region (Central High Atlas, Morocco, five formations are recognised within the Jurassic (Late Sinemurian - Aalenian record. They are organised into seven third order sequences involved in three second order cycles. Three stages characterise the geodynamic evolution of the considered area: 1 Upper Sinemurian -Lower Carixian: lagoonal area; 2 Middle Carixian - Upper Domerian: NE dipping open carbonate platform; and 3 Late Domerian - Aalenian: tectonic activity of the Jbel Tizal -Jbel Azourki fault leading to the setting up of a mosaic sedimentary environments in the study area.Dans la région d’Ait Bou Guemmez (Haut Atlas central, Maroc, la série Jurassique (Sinémurien terminal - l’Aalénien à été subdivisée en cinq formations sédimentaires distinctes. Ces dernières s’organisent en sept séquences de troisième ordre, elles mêmes comprises dans trois cycles de deuxième ordre présentant les maxima de régression au sommet du Carixien inférieur et au Domérien supérieur. L’évolution géodynamique comporte trois étapes successives: 1 Sinémurien terminal - Carixien inférieur: un milieu de lagon limité par des zones émergées ou faiblement subsidentes situées le long de l’accident J.Tizal - J.Azourki; 2 Carixien moyen - Domérien supérieur: vaste plateforme carbonatée ouverte vers le NE; 3 Domérien terminal - Aalénien: intensification dans l’activité tectonique de l’accident de Jbel Tizal - Jbel Azourki, conduisant à la mise en place d’une mosaïque d’environnements sédimentaires dans l’ensemble du secteur étudié.

  12. ANÁLISIS ARQUEOFAUNÍSTICO DEL SITIO PASO DEL TALA (GOYA, CORRIENTES, ARGENTINA / Zooarchaeological study of faunal remains from Paso del Tala site (Goya, Corrientes, Argentina

    Directory of Open Access Journals (Sweden)

    Carolina Barboza

    2014-12-01

    Full Text Available En este trabajo se presentan los resultados del estudio de los restos arqueofaunísticos procedentes del sitio Paso del Tala (Goya, Corrientes, Argentina. Los mismos evidencian la ocupación por parte de grupos prehispánicos en el sector de islas de la llanura aluvial del Paraná Medio durante el Holoceno tardío (356 ± 41 años AP. Se realizó la estimación de la composición anatómica y taxonómica de los conjuntos; se examinaron diferentes aspectos tafonómicos y se evaluaron las modificaciones antrópicas. Los resultados indican que los taxones que habrían sido más explotados por estos grupos están representados principalmente por aquellos característicos de los ambientes fluviales de la zona. Entre ellos se destaca la presencia de especímenes correspondientes a distintas especies de peces, seguidos por mamíferos y roedores, entre los que es importante mencionar la presencia de Hydrochoerus hydrochaeris. Los trabajos de campo permitieron recuperar además del material faunístico, objeto de análisis en el presente trabajo, abundante cantidad de material cerámico, seguido por restos de carbón, material lítico, entre otros. Palabras clave: Zooarqueología, Cazadores-recolectores-pescadores, Llanura aluvial del Paraná Medio, Sector de Islas, Holoceno tardío.   Zooarchaeological study of faunal remains from Paso del Tala site (Goya, Corrientes, Argentina   Abstract This paper presents the analysis of faunal assemblages from Paso del Tala site (Goya, Corrientes, Argentina. This provides new information about hunter-gatherer-fisher occupations in Middle Parana islands during the Late Holocene (356 ± 41 years BP. Remains were identified with regard to anatomy and taxonomy. The focus of the analysis was to differentiate anthropic modification and the action of other agents or taphonomic processes. As a result, the importance of fluvial resources was inferred. Among the taxa that have been identified, fishes, mammals and rodents

  13. Rescuing Middle School Astronomy

    Science.gov (United States)

    Mayo, L. A.; Janney, D.

    2010-12-01

    There is a crisis in education at the middle school level (Spellings, 2006). Recent studies point to large disparities in middle school performance in schools with high minority populations. The largest disparities exist in areas of math and science. Astronomy has a universal appeal for K-12 students but is rarely taught at the middle school level. When it is taught at all it is usually taught in isolation with few references in other classes such as other sciences (e.g. physics, biology, and chemistry), math, history, geography, music, art, or English. The problem is greatest in our most challenged school districts. With scores in reading and math below national averages in these schools and with most state achievement tests ignoring subjects like astronomy, there is little room in the school day to teach about the world outside our atmosphere. Add to this the exceedingly minimal training and education in astronomy that most middle school teachers have and it is a rare school that includes any astronomy teaching at all. In this presentation, we show how to develop and offer an astronomy education training program for middle school teachers encompassing a wide range of educational disciplines that are frequently taught at the middle school level. The prototype for this program was developed and launched in two of the most challenged and diverse school systems in the country; D.C. Public Schools, and Montgomery County (MD) Public Schools.

  14. Lower limits of ornithischian dinosaur body size inferred from a new Upper Jurassic heterodontosaurid from North America.

    Science.gov (United States)

    Butler, Richard J; Galton, Peter M; Porro, Laura B; Chiappe, Luis M; Henderson, Donald M; Erickson, Gregory M

    2010-02-07

    The extremes of dinosaur body size have long fascinated scientists. The smallest (member of the basal dinosaur clade Heterodontosauridae, and is the first member of this clade to be described from North America. The craniodental anatomy and diminutive body size of Fruitadens suggest that this taxon was an ecological generalist with an omnivorous diet, thus providing new insights into morphological and palaeoecological diversity within Dinosauria. Late-surviving (Late Jurassic and Early Cretaceous) heterodontosaurids are smaller and less ecologically specialized than Early (Late Triassic and Early Jurassic) heterodontosaurids, and this ecological generalization may account in part for the remarkable 100-million-year-long longevity of the clade.

  15. 78 FR 47006 - Lemon Juice From Argentina and Mexico

    Science.gov (United States)

    2013-08-02

    ... COMMISSION Lemon Juice From Argentina and Mexico Determination On the basis of the record \\1\\ developed in... investigation on lemon juice from Mexico would not be likely to lead to continuation or recurrence of material... USITC Publication 4418 (July 2013), entitled Lemon Juice from Argentina and Mexico: Investigation...

  16. 78 FR 46610 - Lemon Juice From Argentina and Mexico

    Science.gov (United States)

    2013-08-01

    ... COMMISSION Lemon Juice From Argentina and Mexico Determination On the basis of the record \\1\\ developed in... investigation on lemon juice from Mexico would not be likely to lead to continuation or recurrence of material... USITC Publication 4418 (July 2013), entitled Lemon Juice from Argentina and Mexico: Investigation...

  17. Overview of activities on CANDU fuel in Argentina

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez, L.; Valesi, J., E-mail: lalvarez@cnea.gov.ar [National Commission on Atomic Energy, Fuel Engineering Department (Argentina)

    2013-07-01

    This paper gives an outline of activities on CANDU fuel in Argentina. It discusses the nuclear activities and electricity production in Argentina, evolution of the activities in fuel engineering, fuel fabrication, fuel performance at Embalse nuclear power plant and spent fuel storage options.

  18. Pro-Market Educational Governance: Is Argentina a Black Swan?

    Science.gov (United States)

    Beech, Jason; Barrenechea, Ignacio

    2011-01-01

    In this article we explore ways in which pro-market discourses have been interpreted in policy initiatives in Argentina since the 1970s. Our argument is that even though pro-market discourses have guided reforms in many aspects of public policies in Argentina, the arena of education has overall been resistant to taking them up. The first part of…

  19. Intercultural Citizenship Education in an EFL Online Project in Argentina

    Science.gov (United States)

    Porto, Melina

    2014-01-01

    In this article, I describe an online intercultural citizenship experience in an English as a Foreign Language (EFL) classroom in Argentina. An action research project on the Malvinas/Falklands war fought between Argentina and the UK in 1982 was carried out in 2012. Through a comparative methodology involving Argentine and English foreign language…

  20. Computing and Education in Argentina, Uruguay and Paraguay.

    Science.gov (United States)

    Sadowsky, Manuel

    Although the report is specifically about Argentina, Uruguay and Paraguay, the considerations presented are valid for all of Latin America. In September, 1969, Argentina had approximately 200 electronic computers. The annual growth is estimated at 15-20% and the implementation of teleprocessing and time-sharing systems have made evident the…

  1. Argentina Imp Anti-dumping Duties on Tires from China

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    On June 22, Argentina made the final anti-dumping adjudication once tires from China; on July 6, the Argentina authorities released the No. 221 resolution in 2011 issued by the Ministry of Industry: Impose 23% anti-dumping duties off estate car tires, 10% on the tires of machinery or vehicles used for agriculture and forestation,

  2. Argentina v globalizačních procesech

    OpenAIRE

    Chervets, Tamara

    2009-01-01

    The process of globalization is a very important issue these days. This work will describe the process of globalization in Argentina, especially its economic aspect (foreign direct investments, export and import of goods and services, migration of labor force). I will also mention the history of its development and Argentina's membership in most important international and regional organizations.

  3. Prospect for Development of Open Access in Argentina

    Science.gov (United States)

    Miguel, Sandra; Bongiovani, Paola C.; Gomez, Nancy D.; Bueno-de-la-Fuente, Gema

    2013-01-01

    This perspective article presents an overview of the Open Access movement in Argentina, from a global and regional (Latin American) context. The article describes the evolution and current state of initiatives by examining two principal approaches to Open Access in Argentina: "golden" and "green roads". The article will then…

  4. Tectonic setting of the Jurassic bimodal magmatism in the Sakarya Zone (Central and Western Pontides), Northern Turkey: A geochemical and isotopic approach

    Science.gov (United States)

    Genç, Ş. Can; Tüysüz, Okan

    2010-07-01

    The Lower to Middle Jurassic Mudurnu formation of the Sakarya Zone (Northern Turkey) was deposited in an extensional basin. This unit crops out along the southern Pontide range and consists of marine sedimentary rocks including debris flows, lignite-bearing clastic rocks and Ammonitico Rosso horizons alternating with mafic and felsic volcanic and volcaniclastic rocks. Magmatic rocks of the Mudurnu formation comprise two compositionally different groups; 1) a mafic group including diabase-microgabbro-basaltic lavas and their pyroclastic equivalents, and 2) a felsic group including granite porphyries and felsic pyroclastic rocks. All the magmatic members of the Mudurnu formation are subalkaline and display a calc-alkaline affinity. They are bimodal, with a significant silica gap between the mafic and felsic members with the exception of a few samples. These magmatic rocks display enrichment in LILE and depletion in Nb, Ta, P and Ti, implying a subduction-related magmatic signature. Melting modelling for the mafic rocks indicates that they originated possibly from subcontinental lithospheric mantle (SCLM) composed of spinel lherzolite. ɛNd(i) values (+ 1.5 to + 4.3) imply that the mafic volcanic and hypabyssal rocks were possibly derived from a time-integrated LREE-depleted mantle source. The initial Sr and Nd isotope values, and ɛNd(i) of the felsic hypabyssal rocks are comparable to the mafic ones. The isotope data point to a genetic relationship between the felsic and mafic members. Results obtained from the geochemical modelling of incompatible versus compatible trace elements show that the felsic rocks were derived from the mafic melts by fractional crystallization (FC) process. In the light of their regional geological setting and these geochemical characteristics, we propose that the magmatic rocks of the Mudurnu formation formed in an extensional basin situated on an active and/or just ended subduction zone during the Jurassic period. The Mudurnu formation

  5. Precious metal-bearing epithermal deposits in western Patagonia (NE Lago Fontana region), Argentina

    Science.gov (United States)

    Lanfranchini, Mabel Elena; Etcheverry, Ricardo Oscar; de Barrio, Raúl Ernesto; Recio Hernández, Clemente

    2013-04-01

    Precious metal-bearing quartz veins occur at the northeastern sector of the Lago Fontana region in southwestern Argentina, within the context of the Andean continental magmatic arc environment. The deposits and their associated alteration zones are spatially related to a Cretaceous calc-alkaline magmatism represented by silicic dikes and hypabyssal intrusions, and hosted by a Late Jurassic to Cretaceous volcano-sedimentary sequence. The veins and related veinlets crop out discontinuously, in general terms in a NW-SE belt. The primary vein mineral assemblage is composed mostly of pyrite ± galena ± chalcopyrite > hematite ± arsenopyrite in silica gangue minerals. Chemical analyses of grab samples from selected quartz veins show as much as 5.7 ppm Au and 224 ppm Ag, as well as elevated Pb, Cu, and Zn. Hydrothermal fluids caused an innermost silicification and adularia-sericite alteration assemblage, and an external propylitic halo. Sulfur isotope values measured for sulfides (δSS from -1.90 to +1.56‰), and oxygen and hydrogen isotopes measured on quartz crystals and extracted primary fluid inclusion waters (δOO = -2.85 to +5.40‰; δDO = -106.0 to -103.4‰) indicate that mineralization probably formed from magmatic fluids, which were mixed with meteoric waters. Also, fluid inclusion data from quartz veins point out that these fluids had low salinity (1.7-4.2 wt% NaCl equiv.), and temperatures of homogenization between 180 and 325 °C. Mineralogical, petrographic and geochemical features for mineralized surface exposures indicate a typical adularia-sericite, low sulfidation epithermal system in the Lago Fontana area that represents a promising target for further exploration programs.

  6. 75 FR 23674 - Honey from Argentina: Final Results of Antidumping Duty Administrative Review and Determination...

    Science.gov (United States)

    2010-05-04

    ... International Trade Administration A-357-812 Honey from Argentina: Final Results of Antidumping Duty... antidumping duty order on honey from Argentina. See Honey from Argentina: Preliminary Results of Antidumping... preliminary results of the administrative review of the antidumping duty order on honey from Argentina for...

  7. The rediscovery and redescription of the holotype of the Late Jurassic turtle Plesiochelys etalloni

    Directory of Open Access Journals (Sweden)

    Jérémy Anquetin

    2014-02-01

    Full Text Available Plesiochelyidae are a major component of Late Jurassic shallow marine environments throughout Europe. However, the taxonomy of plesiochelyid turtles is rather confused. Over the years, many taxa have been synonymized with Plesiochelys etalloni, one of the first described species. However, the holotype of P. etalloni (and only specimen known from Lect, the type locality was lost for more than 150 years. This specimen has been recently rediscovered in the collections of the Musée d’archéologie du Jura in Lons-le-Saunier, France. For the first time since its original description in 1857, the holotype of P. etalloni is redescribed and compared to relevant material. The taxonomic status of this taxon is revised accordingly. Based on the morphology of the newly rediscovered holotype and on a reassessment of specimens from Solothurn (Switzerland, the species P. solodurensis, P. sanctaeverenae and P. langii are synonymized with P. etalloni. Known skull-shell associations for P. etalloni are re-evaluated in light of the new morphological information available since the rediscovery of this holotype specimen. Finally, we confirm that Plesiochelys is represented by a single species in the Late Jurassic of the Jura Mountains.

  8. Bird-like anatomy, posture, and behavior revealed by an early jurassic theropod dinosaur resting trace.

    Directory of Open Access Journals (Sweden)

    Andrew R C Milner

    Full Text Available BACKGROUND: Fossil tracks made by non-avian theropod dinosaurs commonly reflect the habitual bipedal stance retained in living birds. Only rarely-captured behaviors, such as crouching, might create impressions made by the hands. Such tracks provide valuable information concerning the often poorly understood functional morphology of the early theropod forelimb. METHODOLOGY/PRINCIPAL FINDINGS: Here we describe a well-preserved theropod trackway in a Lower Jurassic ( approximately 198 million-year-old lacustrine beach sandstone in the Whitmore Point Member of the Moenave Formation in southwestern Utah. The trackway consists of prints of typical morphology, intermittent tail drags and, unusually, traces made by the animal resting on the substrate in a posture very similar to modern birds. The resting trace includes symmetrical pes impressions and well-defined impressions made by both hands, the tail, and the ischial callosity. CONCLUSIONS/SIGNIFICANCE: The manus impressions corroborate that early theropods, like later birds, held their palms facing medially, in contrast to manus prints previously attributed to theropods that have forward-pointing digits. Both the symmetrical resting posture and the medially-facing palms therefore evolved by the Early Jurassic, much earlier in the theropod lineage than previously recognized, and may characterize all theropods.

  9. Geochemical characteristics of fossil Solenites murrayana cuticles from the Jurassic in Lanzhou, northwest China

    Energy Technology Data Exchange (ETDEWEB)

    Sun, B.N.; Yan, D.F.; Xie, S.P.; Shi, Y.J.; Zhang, C.J.; Lin, Z.C. [Lanzhou University, Lanzhou (China)

    2006-07-01

    Through geochemical analysis on cuticles of the Jurassic fossil Solenites murrayuna L. et H. from the Yaojie Coalfield in Lanzhou, northwest China, and by comparison of geochemical features with its nearest living equivalent, Ginkgo biloba, we show that the characteristics of organic matter of the fossil plant cuticles accord with evolutionary features of asphalt in oil formation. The content analysis of organic matter indicates that the geochemistry is equivalent to rotten mud-sapropel humus types from Mesozoic and Cenozoic source rock in China. Some analysis data of organic matter indicate that Solenites murrayana cuticles are in a low mature stage, which coincides with the hydrocarbon generation model of cutinite in coal. Moreover, distribution features of soluble organic matter of cuticles show that fossil plant cuticles have a definite action in forming terrestrial high-wax oil, which has testified the contribution of high plants to waxness. The present study proves that Ginkgophytes abundant in the Jurassic were a high potential plant in the formation of coal-bed hydrocarbon.

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

    Science.gov (United States)

    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.

  11. Structural complexity at and around the Triassic-Jurassic GSSP at Kuhjoch, Northern Calcareous Alps, Austria

    Science.gov (United States)

    Palotai, M.; Pálfy, J.; Sasvári, Á.

    2017-02-01

    One of the key requirements for a Global Stratotype Section and Point (GSSP) is the absence of tectonic disturbance. The GSSP for the Triassic-Jurassic system boundary was recently defined at Kuhjoch, Northern Calcareous Alps, Austria. New field observations in the area of the Triassic-Jurassic boundary GSSP site demonstrate that the overturned, tight, and almost upright Karwendel syncline was formed at semibrittle deformation conditions, confirmed by axial planar foliation. Tight to isoclinal folds at various scales were related to a tectonic transport to the north. Brittle faulting occurred before and after folding as confirmed by tilt tests (the rotation of structural data by the average bedding). Foliation is ubiquitous in the incompetent units, including the Kendlbach Formation at the GSSP. A reverse fault (inferred to be formed as a normal fault before folding) crosscuts the GSSP sections, results in the partial tectonic omission of the Schattwald Beds, and thus makes it impossible to measure a complete and continuous stratigraphic section across the whole Kendlbach Formation. Based on these observations, the Kuhjoch sections do not fulfil the specific requirement for a GSSP regarding the absence of tectonic disturbances near boundary level.

  12. Marine ecosystem resilience during extreme deoxygenation: the Early Jurassic oceanic anoxic event.

    Science.gov (United States)

    Caswell, Bryony A; Frid, Christopher L J

    2017-01-01

    Global warming during the Early Jurassic, and associated widespread ocean deoxygenation, was comparable in scale with the changes projected for the next century. This study quantifies the impact of severe global environmental change on the biological traits of marine communities that define the ecological roles and functions they deliver. We document centennial-millennial variability in the biological trait composition of Early Jurassic (Toarcian) seafloor communities and examine how this changed during the event using biological traits analysis. Environmental changes preceding the global oceanic anoxic event (OAE) produced an ecological shift leading to stressed benthic palaeocommunities with reduced resilience to the subsequent OAE. Changes in traits and ecological succession coincided with major environmental changes; and were of similar nature and magnitude to those in severely deoxygenated benthic communities today despite the very different timescales. Changes in community composition were linked to local redox conditions whereas changes in populations of opportunists were driven by primary productivity. Throughout most of the OAE substitutions by tolerant taxa conserved the trait composition and hence functioning, but periods of severe deoxygenation caused benthic defaunation that would have resulted in functional collapse. Following the OAE recovery was slow probably because the global nature of the event restricted opportunities for recruitment from outside the basin. Our findings suggest that future systems undergoing deoxygenation may initially show functional resilience, but severe global deoxygenation will impact traits and ecosystem functioning and, by limiting the species pool, will slow recovery rates.

  13. The first elateroid beetles (Coleoptera: Polyphaga: Elateroidea) from the Upper Jurassic of Australia.

    Science.gov (United States)

    Oberprieler, Rolf G; Ashman, Lauren G; Frese, Michael; Ślipiński, Adam

    2016-08-03

    The first elateroid fossils from the Upper Jurassic Talbragar Fish Bed in Australia are described and illustrated. Wongaroo amplipectorale gen. et sp. n., based on two specimens, is placed in the family Cerophytidae due to its convex, posteriorly weakly angled and laterally carinate pronotum obscuring the head in dorsal view, its relatively long, pointed elytra and slender legs, its 9-striate elytra with deep basal pits and the absence of metacoxal plates. Beattieellus jurassicus gen. et sp. n., described from one specimen, possesses the acutely angled pronotum without a carina on the posterolateral angles and the ventral click apparatus typical of Eucnemidae and is classified in this family. Assignment of it to a eucnemid subfamily is impossible because of the insufficient preservation of relevant characters in the fossil. Four other elateroid fossils, possibly representing eucnemids and elaterids, are illustrated and briefly described but not named, due to their insufficient preservation. These fossils represent the first of their kind in Australia and in the Southern Hemisphere, and Beattieellus is also the oldest eucnemid fossil known and extends the fossil record of Eucnemidae into the Upper Jurassic. The discovery of elateroid fossils in the Talbragar Fish Bed adds to the coleopteran diversity of this ancient lake ecosystem, indicating that it was well wooded and provided suitable habitats of rotten wood for the development of the larvae of these taxa.

  14. Bird-Like Anatomy, Posture, and Behavior Revealed by an Early Jurassic Theropod Dinosaur Resting Trace

    Science.gov (United States)

    Milner, Andrew R. C.; Harris, Jerald D.; Lockley, Martin G.; Kirkland, James I.; Matthews, Neffra A.

    2009-01-01

    Background Fossil tracks made by non-avian theropod dinosaurs commonly reflect the habitual bipedal stance retained in living birds. Only rarely-captured behaviors, such as crouching, might create impressions made by the hands. Such tracks provide valuable information concerning the often poorly understood functional morphology of the early theropod forelimb. Methodology/Principal Findings Here we describe a well-preserved theropod trackway in a Lower Jurassic (∼198 million-year-old) lacustrine beach sandstone in the Whitmore Point Member of the Moenave Formation in southwestern Utah. The trackway consists of prints of typical morphology, intermittent tail drags and, unusually, traces made by the animal resting on the substrate in a posture very similar to modern birds. The resting trace includes symmetrical pes impressions and well-defined impressions made by both hands, the tail, and the ischial callosity. Conclusions/Significance The manus impressions corroborate that early theropods, like later birds, held their palms facing medially, in contrast to manus prints previously attributed to theropods that have forward-pointing digits. Both the symmetrical resting posture and the medially-facing palms therefore evolved by the Early Jurassic, much earlier in the theropod lineage than previously recognized, and may characterize all theropods. PMID:19259260

  15. Fossil evidence on evolution of inner ear cochlea in Jurassic mammals.

    Science.gov (United States)

    Luo, Zhe-Xi; Ruf, Irina; Schultz, Julia A; Martin, Thomas

    2011-01-07

    The coiled cochlea is a key evolutionary innovation of modern therian mammals. We report that the Late Jurassic mammal Dryolestes, a relative to modern therians, has derived bony characteristics of therian-like innervation, but its uncoiled cochlear canal is less derived than the coiled cochlea of modern therians. This suggests a therian-like innervation evolved before the fully coiled cochlea in phylogeny. The embryogenesis of the cochlear nerve and ganglion in the inner ear of mice is now known to be patterned by neurogenic genes, which we hypothesize to have influenced the formation of the auditory nerve and its ganglion in Jurassic therian evolution, as shown by their osteological correlates in Dryolestes, and by the similar base-to-apex progression in morphogenesis of the ganglion in mice, and in transformation of its canal in phylogeny. The cochlear innervation in Dryolestes is the precursory condition in the curve-to-coil transformation of the cochlea in mammalian phylogeny. This provides the timing of the evolution, and where along the phylogeny the morphogenetic genes were co-opted into patterning the cochlear innervation, and the full coiling of the cochlea in modern therians.

  16. JURASSIC HERITAGE OF PORTUGAL: STATE OF THE ART AND OPEN PROBLEMS

    Directory of Open Access Journals (Sweden)

    MARIA HELENA HENRIQUES

    2004-03-01

    Full Text Available The aim of this work is to present a general view on the situation of Jurassic sites outcropping in Portugal, in particular those located in the Lusitanian Basin, which represent geosites with heritage value. The legal instruments on geoconservation are generically presented, and they happen to be designed for Natural Heritage deeply confused with the Biological Heritage. No specific law for geological values exist in Portugal, but the general law on Natural Conservation has allowed the protection of five geosites of national relevance as Natural Monuments. They correspond to a small area when compared to the whole national area of Protected Sites, and they all correspond to dinosaur tracksites of Jurassic and Cretaceous age. Geosites of regional relevance have been also protected using municipal laws and they show important public use, sometimes giving rise to reference museums and to continuous pedagogical actions. On the other hand, geosites of international relevance for its stratigraphic value (the Bajocian GSSP at Cabo Mondego section, the candidate to the Toarcian GSSP at Peniche section have no formal protection and classification according to the Portuguese laws. They remain safe because they are located on the coast, which is protected due to other environmental laws. Their integration in a supra-national framework supported by UNESCO is obviously recommended and it would be of great impact among the national institutions with formal responsibilities on the Natural Heritage.

  17. Bird-like anatomy, posture, and behavior revealed by an early jurassic theropod dinosaur resting trace

    Science.gov (United States)

    Milner, A.R.C.; Harris, J.D.; Lockley, M.G.; Kirkland, J.I.; Matthews, N.A.

    2009-01-01

    Background: Fossil tracks made by non-avian theropod dinosaurs commonly reflect the habitual bipedal stance retained in living birds. Only rarely-captured behaviors, such as crouching, might create impressions made by the hands. Such tracks provide valuable information concerning the often poorly understood functional morphology of the early theropod forelimb. Methodology/Principal Findings: Here we describe a well-preserved theropod trackway in a Lower Jurassic (???198 millionyear- old) lacustrine beach sandstone in the Whitmore Point Member of the Moenave Formation in southwestern Utah. The trackway consists of prints of typical morphology, intermittent tail drags and, unusually, traces made by the animal resting on the substrate in a posture very similar to modern birds. The resting trace includes symmetrical pes impressions and well-defined impressions made by both hands, the tail, and the ischial callosity. Conclusions/Significance: The manus impressions corroborate that early theropods, like later birds, held their palms facing medially, in contrast to manus prints previously attributed to theropods that have forward-pointing digits. Both the symmetrical resting posture and the medially-facing palms therefore evolved by the Early Jurassic, much earlier in the theropod lineage than previously recognized, and may characterize all theropods.

  18. Late Triassic - Early Jurassic successions of the Atuel depocenter: sequence stratigraphy and tectonic controls

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    Silvia Lanés

    2008-12-01

    Full Text Available Biostratigraphic correlations of the Late Triassic - Early Jurassic successions of the Atuel depocenter allowed determining the accommodation changes and the possible tectonic controls on sedimentation. The Rhaetian - late Early Sinemurian deposits contain facies of slope-type fan deltas, braided fluvial systems and low sinuosity rivers with alternate bars deposited during a synrift phase. The late Early Sinemurian - Toarcian series host facies of intermediate (Gilbert to shelf type fan deltas, braided and low sinuosity fluvial systems, wave-dominated estuaries, transgressive storm-dominated and turbidite-influenced marine shelves which record the sag phase. According to different criteria two stratigraphic schemes are proposed, the first one considering tectosedimentary units (TSU and the second one using "Exxon-like" sequences. In the first scheme the synrift TSU matches the actual Precuyo Mesosequence and the sag TSU is partly equivalent to the Cuyo Mesosequence, mainly keeping the current mesosequence scheme for the Neuquén basin but assigning the fandeltaic deposits to the Precuyo Mesosequence. The second sequence scheme considers the whole Late Triassic - Early Jurassic succession as a part of the Cuyo Mesosequence, where the synrift deposits composes the detached lowstand system tract (LST and most of the sag deposits makes the transgressive system tract (TST. The basal sequence boundary does not crop out, the flooding surface at the TST base and the maximum flooding surface at the TST top are respectively marked by the lowest estuarine levels and by black shales with suboxic-compatible bivalves (Bositra sp..

  19. Base level change and depositional filling response of Jurassic in the Qiangtang Basin of Tibet

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The base level during the deposition of Jurassic in the Qiangtang Basin shows a complete cycle from rising to falling. The base level change is closely connected with tectonic evolution of the basin,especially connected with Bangonghu-Nujiang ocean evolution process in the formation and evolution of the basin. It is also affected by climate. The Jurassic strata correspond to a long-term base level cycle sequence. The sequence is in fact a non-complete symmetrical cycle,consisting of rising hemicycle and falling hemicycle. It can be divided into 6 intermediate-term base level cycle sequences,including 2 carbonate sequences,3 mixture sedimentary sequences of carbonate and clastic rocks and one clastic sedimentary sequence. Depositional filling characteristics during base level change show that Bangonghu-Nujiang ocean spreads in Toarcian-Bajocian ages,and is at the height of spreading of Bangonghu-Nujiang ocean in Bathonian-Oxfordian ages. In that process,sea area became smaller because of the dry climate. Eventually,marine depositional filling is ended with the subduction and collision of Bangonghu-Nujiang ocean.

  20. Age constraints on the dispersal of dinosaurs in the Late Triassic from magnetochronology of the Los Colorados Formation (Argentina).

    Science.gov (United States)

    Kent, Dennis V; Santi Malnis, Paula; Colombi, Carina E; Alcober, Oscar A; Martínez, Ricardo N

    2014-06-03

    A measured magnetozone sequence defined by 24 sampling sites with normal polarity and 28 sites with reverse polarity characteristic magnetizations was established for the heretofore poorly age-constrained Los Colorados Formation and its dinosaur-bearing vertebrate fauna in the Ischigualasto-Villa Union continental rift basin of Argentina. The polarity pattern in this ∼600-m-thick red-bed section can be correlated to Chrons E7r to E15n of the Newark astrochronological polarity time scale. This represents a time interval from 227 to 213 Ma, indicating that the Los Colorados Formation is predominantly Norian in age, ending more than 11 My before the onset of the Jurassic. The magnetochronology confirms that the underlying Ischigualasto Formation and its vertebrate assemblages including some of the earliest known dinosaurs are of Carnian age. The oldest dated occurrences of vertebrate assemblages with dinosaurs in North America (Chinle Formation) are younger (Norian), and thus the rise of dinosaurs was diachronous across the Americas. Paleogeography of the Ischigualasto and Los Colorados Formations indicates prolonged residence in the austral temperate humid belt where a provincial vertebrate fauna with early dinosaurs may have incubated. Faunal dispersal across the Pangean supercontinent in the development of more cosmopolitan vertebrate assemblages later in the Norian may have been in response to reduced contrasts between climate zones and lowered barriers resulting from decreasing atmospheric pCO2 levels.

  1. Magnetochronology of the LOS Colorados Formation (argentina): Late Triassic Terrestrial Biogeography and the Delayed Dispersal of Dinosaurs

    Science.gov (United States)

    Kent, D. V.; Santi Malnis, P.; Colombi, C.; Alcober, O.; Martinez, R.

    2013-12-01

    A measured magnetozone sequence defined by 24 sampling sites with normal polarity and 28 sites with reverse polarity characteristic magnetizations was established for the heretofore poorly age-constrained Los Colorados Formation and its enigmatic vertebrate fauna in the Ischigualasto-Villa Union continental rift basin of Argentina. The polarity pattern in this ~600 m-thick redbed section can be correlated to Chrons E7r to E15n of the Newark astronomical polarity time scale. This represents a time interval from 227 to 213 Ma, indicating that the Los Colorados Formation is entirely Norian in age with no Rhaetian strata and ending more than 11 Myr before the onset of the Jurassic. The magnetochronology also implies that the underlying Ischigualasto Formation and its vertebrate assemblages including the earliest known dinosaurs are confined to the Carnian, consistent with recently published radioisotopic dates. A paleogeographic reconstruction and simplified zonal climate model indicate that the Ischigualasto and Los Colorados Formations were deposited in the austral temperate humid belt that apparently allowed the incubation of a unique vertebrate fauna with early dinosaurs that only dispersed across the tropics to the Northern Hemisphere in the later Norian. The faunal dispersal across the Pangean supercontinent may have been in response to sufficiently reduced contrasts between climate zones in non-polar regions resulting from decreasing atmospheric pCO2 levels.

  2. Long-term landscape development: a perspective from the southern Buenos Aires ranges of east central Argentina

    Science.gov (United States)

    Demoulin, A.; Zarate, M.; Rabassa, J.

    2005-06-01

    Traditionally, the long-term landscape evolution of the southern Buenos Aires ranges of east central Argentina has been related to the influence of the Andean orogeny. We describe the large-scale morphological units and associated weathering products in the Tandilia and Ventania ranges. Two main planation surfaces are encountered at varying altitudes in different sectors of these ranges. The lower surface is characterized by roots of kaolinized weathering profiles in the Tandil area and silicified conglomerates around Sierra de La Ventana. In an interpretative model linking the range morphogenesis to the tectonosedimentary evolution of the bordering Salado and Colorado Basins, we suggest that the main morphogenetic stages are related to the late Jurassic-early Cretaceous south Atlantic rifting and Miocene tectonic reactivation induced by the Andean orogeny. Thus, the uplifted surfaces appear much older than commonly believed: pre-Cretaceous and Paleogene. Although they contradict recent results of apatite fission-track studies along the South America and South Africa passive margins, the implied low denudation rates (˜4 m/My) can be explained by the limited Meso-Cenozoic uplift suffered by the southern Buenos Aires ranges. The discussion also shows the limits of the comparison that can be made with the South African planation surfaces.

  3. Cenozoic diatreme field in Chubut (Argentina) as evidence of phreatomagmatic volcanism accompanied with extensive Patagonian plateau basalt volcanism?

    Institute of Scientific and Technical Information of China (English)

    Károly Németh; Ulrike Martin; Miguel J. Haller; Viviana L Alric

    2007-01-01

    @@ In Patagonia, Argentina, at the northern border of the Patagonian Cenozoic mafic plateau lava fields, newly discovered diatremes stand about 100 m above the surrounding plain. These diatremes document phreatomagmatic episodes associated with the formation of the volcanic fields. The identified pyroclastic and intrusive rocks are exposed lower diatremes of former phreatomagmatic volcanoes and their feeding dyke systems.These remotely located erosional remnants cut through Paleozoic granitoids and Jurassic/Cretaceous alternating siliciclastic continental successions that are relatively easily eroded. Plateau lava fields are generally located a few hundreds of metres above the highest level of the present tops of the preserved diatremes suggesting a complex erosional history and potential interrelation-ships between the newly identified diatremes and the surrounding lava fields. Uprising magma from theunderlying feeder dyke into the diatreme root zone intruded the clastic debris in the diatremes, inflated them and mingled with the debris to form subterranean peperite. The significance of identifying diatremes in Patagonia are twofold: 1) in the syn-eruptive paleoenvironment, water was available in various "soft-sediments", commonly porous, media aquifer sources, and 2) the identified abundant diatremes that form diatreme fields are good source candidates for the extensive lava fields with phreatomagmatism facilitating magma rise with effective opening of fissures before major lava effusions.

  4. Bibliografia Bibliotecologica Argentina [Hasta 1967] (A Bibliography of Library Science in Argentina [to 1967]).

    Science.gov (United States)

    Matijevic, Nicolas, Comp.

    A guide to library services, management, and organization is offered to professionals in this comprehensive bibliography, written in Spanish, of approximately 2500 items. Published by the Universidad Nacional del Sur (The National University of the South) in Bahia Blanca, Argentina, the list covers books, articles, monographs, manuals, catalogs,…

  5. Cadenas productivas y disponibilidad de alimentos en Argentina Productive chains and food availability in Argentina

    Directory of Open Access Journals (Sweden)

    Malena Giai

    2010-06-01

    Full Text Available En abril de 2009 se conformó en la Asociación Argentina de Dietistas y Nutricionistas Dietistas el Grupo de Estudio sobre Soberanía Alimentaria, constituido por un grupo de Licenciados en Nutrición con interés en el tema. Como primer objetivo, el Grupo se propuso estudiar tres temas: "el Derecho a la Alimentación", "la Producción y Disponibilidad de alimentos en Argentina" y "la Canasta Básica de Alimentos". En el presente artículo se expone un resumen de los avances en el segundo tema mencionado.In April 2009, was formed in the Argentina Association of Dieticians and Nutritionists Dietitians the Study Group on Food Sovereignty, established by a group of graduates in nutrition with interest in the subject. As a first objective, the Group was to examine three issues: "The Right to Food", "Production and Availability of food in Argentina" and "Basic Food Basket." This article is a summary of progress on the second topic mentioned.

  6. La familia Cyatheaceae (Pteridophyta en Argentina The family Cyatheaceae (Pteridophyta in Argentina

    Directory of Open Access Journals (Sweden)

    Gonzalo J Marquez

    2010-06-01

    Full Text Available La familia Cyatheaceae comprende alrededor de 500 especies de helechos arborescentes. Su distribución es pantropical y en Argentina se encuentra representada por 4 especies, reunidas en los géneros Alsophila y Cyathea: A. setosa, A. odonelliana, C. atrovirens y C. delgadii. En este trabajo se presenta una actualización de la información disponible hasta el momento referente a estas especies. Se exponen microfotografías de las esporas, que presentan la superficie con lomos en Alsophila y con cordones en Cyathea. Se ilustran los indusios y escamas de la base de los pecíolos, que son de importancia fundamental para la diferenciación de las especies estudiadas. Asimismo se presenta un mapa de distribución y una clave de las especies que crecen en Argentina.The family Cyatheaceae comprises about 500 species of tree ferns. Their distribution is pantropical and in Argentina is represented by four species, grouped in genera Alsophila y Cyathea: A. setosa, A. odonelliana, C. atrovirens and C. delgadii. In this paper, an update of the available information of the mentioned species is presented. A key to diferentiate the species growing in Argentina, their descriptions and a distribution map are also given. Spores are ridged in Alsophila and with rodlets in Cyathea. Indusia and scales of petiole basis are also illustrated.

  7. Middle managers service leadership

    Directory of Open Access Journals (Sweden)

    Lucio Roberto Lescano Duncan

    2011-12-01

    Full Text Available A big challenge in modern service organization is to focus on customers and to forge their satisfaction and loyalty. Innovation, information technology and value added are decisive factors, however the main aspect to consider is the human factor. It is necessary to focus on people in order to improve the service capability within the organization.Middle manager is the link between the strategy designed by top management and the execution to deliver services, that is realized by employees guided by leaders of middle level. Our study is focused on middle manager service orientation as the pillar to get a customer focus and to forge the service employees' performance.We consider that middle managers have to asume a service leadership in order to foster the productivity and employees' commitment. In that sense we focus especially on middle managers' main roles. Those are the key aspect to deploy a service culture, and at the same time to promote employees' satisfaction that drives their performance and development.

  8. Characterization of oil source strata organic matter of Jurassic age and its contribution to the formation of oil and gas deposits

    Science.gov (United States)

    Pronin, Nikita; Nosova, Fidania; Plotnikova, Irina

    2013-04-01

    continental organics to the composition of the original substance. Thus the type of organic matter of these deposits is humus. According to all information received, organic matter of the rocks of Vasyuganskaya suite is catageneticly poorly transfomed. 4. Georgievskaya suite. Accumulation of OM in this strata occurred in shallow marine strongly reducing conditions. According to its type, this matter is sapropel, and plankton-algal composition was the source material for it. Its accumulation occurred in terrigenous clay sediments. Organic matter of Georgievskaya suite is situated in the area of moderate maturity. Also the traces of oxidation and of some contribution of ground vegetation were revealed in the OM, all that somewhat reduces the oil and gas generating potential of this strata. 5. Bazhenovskaya suite. The organic matter under the study accumulated mainly in shallow marine reducing conditions. Some small residue of ground vegetation is detected in the deeper layers. The type of the Bazhenovskaya suite organic matter is defined as sapropel. The source matter for this organics is a mixed - bacterial and algal type. OM is characterized of sufficiently high maturity. Thus, as a result of the complex geochemical studies several strata that might participate in the formation of oil and gas deposits were revealed. These strata include Tyumenskaya suite of the middle segment, Georgievskaya the Bazhenovskaya suites the upper segment of the Jurassic system. Composition of the OM of these strata, the conditions of accumulation and the degree of their catagenetic transformation allows us to label them as having great potential, and as probably effective oil source strata

  9. Tobacco industry targeting youth in Argentina

    Science.gov (United States)

    Braun, S; Mejia, R; Ling, P M; Pérez-Stable, E J

    2013-01-01

    Background/aim Argentina has one of the highest cigarette smoking rates among both men and women in the Americas and no legislated restrictions on tobacco industry advertising. The tobacco industry has traditionally expanded markets by targeting adolescents and young adults. The objective of this study was to determine whether and how the tobacco industry promotes cigarettes to adolescents in Argentina. Methods We conducted a systematic search of tobacco industry documents available through the internet dated between 1995 and 2004 using standard search terms to identify marketing strategies in Argentina. A selected review of the four leading newspapers and nine magazines with reported high readership among adolescents was completed. The selected print media were searched for tobacco images and these were classified as advertisements if associated with a commercial product or as a story if not. Results The tobacco industry used market segmentation as a strategy to target Argentinean consumers. British American Tobacco (BAT) undertook a young adult psychographic study and classified them as “progressives”, “Jurassics” or “conservatives” and “crudos” or “spoiled brats”. BAT marketed Lucky Strike to the “progressives” using Hollywood movies as a vehicle. The tobacco industry also targeted their national brands to the conservatives and linked these brands with “nationalistic values” in advertising campaigns. Philip Morris promoted Marlboro by sponsoring activities directed at young people and they launched the 10 cigarettes packet as a starter vehicle. Conclusions The tobacco industry used psychographic segmentation of the population and developed advertising strategies focused on youth. Tobacco control researchers and advocates must be able to address these strategies in counter-marketing interventions. PMID:18299308

  10. Assessment of undiscovered oil and gas resources in Jurassic and Cretaceous strata of the Gulf Coast, 2010

    Science.gov (United States)

    Dubiel, Russell F.; Warwick, Peter D.; Swanson, Sharon; Burke, Lauri; Biewick, Laura R.H.; Charpentier, Ronald R.; Coleman, James L.; Cook, Troy A.; Dennen, Kris; Doolan, Colin; Enomoto, Catherine; Hackley, Paul C.; Karlsen, Alexander W.; Klett, Timothy R.; Kinney, Scott A.; Lewan, Michael D.; Merrill, Matt; Pearson, Krystal; Pearson, Ofori N.; Pitman, Janet K.; Pollastro, Richard M.; Rowan, Elizabeth L.; Schenk, Christopher J.; Valentine, Brett

    2011-01-01

    Using a geology-based assessment methodology, the U.S. Geological Survey estimated means of 147.4 trillion cubic feet of undiscovered natural gas, 2.4 billion barrels of undiscovered oil, and 2.96 billion barrels of undiscovered natural gas liquids in Jurassic and Cretaceous strata in onshore lands and State waters of the Gulf Coast.

  11. Multivariate and Cladistic Analyses of Isolated Teeth Reveal Sympatry of Theropod Dinosaurs in the Late Jurassic of Northern Germany.

    Directory of Open Access Journals (Sweden)

    Oliver Gerke

    Full Text Available Remains of theropod dinosaurs are very rare in Northern Germany because the area was repeatedly submerged by a shallow epicontinental sea during the Mesozoic. Here, 80 Late Jurassic theropod teeth are described of which the majority were collected over decades from marine carbonates in nowadays abandoned and backfilled quarries of the 19th century. Eighteen different morphotypes (A-R could be distinguished and 3D models based on micro-CT scans of the best examples of all morphotypes are included as supplements. The teeth were identified with the assistance of discriminant function analysis and cladistic analysis based on updated datamatrices. The results show that a large variety of theropod groups were present in the Late Jurassic of northern Germany. Identified specimens comprise basal Tyrannosauroidea, as well as Allosauroidea, Megalosauroidea cf. Marshosaurus, Megalosauridae cf. Torvosaurus and probably Ceratosauria. The formerly reported presence of Dromaeosauridae in the Late Jurassic of northern Germany could not be confirmed. Some teeth of this study resemble specimens described as pertaining to Carcharodontosauria (morphotype A and Abelisauridae (morphotype K. This interpretation is however, not supported by discriminant function analysis and cladistic analysis. Two smaller morphotypes (N and Q differ only in some probably size-related characteristics from larger morphotypes (B and C and could well represent juveniles of adult specimens. The similarity of the northern German theropods with groups from contemporaneous localities suggests faunal exchange via land-connections in the Late Jurassic between Germany, Portugal and North America.

  12. Jurassic-Cretaceous Herpetofaunas from the Jehol Associated Strata in NE China:Evolutionary and Ecological Implications

    Institute of Scientific and Technical Information of China (English)

    WANG Yuan; DONG Liping; Susan E.EVANS

    2010-01-01

    @@ Jurassic-Cretaceous herpetofaunas have recently been recovered from tuffinterbedded lacustrine strata in northeastern(NE)China.Most of them are from the Early Cretaceous Jehol Group(131-120 Ma),which has yielded a diverse and important fossil assemblage including insects,plants,fishes and tetrapods.

  13. Tectonic interactions between India and Arabia since the Jurassic reconstructed from marine geophysics, ophiolite geology, and seismic tomography

    NARCIS (Netherlands)

    Gaina, Carmen; Van Hinsbergen, Douwe J J; Spakman, Wim

    2015-01-01

    Gondwana breakup since the Jurassic and the northward motion of India toward Eurasia were associated with formation of ocean basins and ophiolite obduction between and onto the Indian and Arabian margins. Here we reconcile marine geophysical data from preserved oceanic basins with the age and locati

  14. First Description of Genuine Shatter Cones in Upper Jurassic Limestone Clasts from the Bunte Breccia Impactites of the Ries Crater

    Science.gov (United States)

    Poesges, G. A.

    2016-08-01

    The Ries crater produced a wealth of lithologies that host shatter cones. This study reviews the occurrence of shatter cones in the Ries crater and reports the first finds of shatter cones in Upper Jurassic limestone clasts within the Bunte Breccia.

  15. Multivariate and Cladistic Analyses of Isolated Teeth Reveal Sympatry of Theropod Dinosaurs in the Late Jurassic of Northern Germany.

    Science.gov (United States)

    Gerke, Oliver; Wings, Oliver

    2016-01-01

    Remains of theropod dinosaurs are very rare in Northern Germany because the area was repeatedly submerged by a shallow epicontinental sea during the Mesozoic. Here, 80 Late Jurassic theropod teeth are described of which the majority were collected over decades from marine carbonates in nowadays abandoned and backfilled quarries of the 19th century. Eighteen different morphotypes (A-R) could be distinguished and 3D models based on micro-CT scans of the best examples of all morphotypes are included as supplements. The teeth were identified with the assistance of discriminant function analysis and cladistic analysis based on updated datamatrices. The results show that a large variety of theropod groups were present in the Late Jurassic of northern Germany. Identified specimens comprise basal Tyrannosauroidea, as well as Allosauroidea, Megalosauroidea cf. Marshosaurus, Megalosauridae cf. Torvosaurus and probably Ceratosauria. The formerly reported presence of Dromaeosauridae in the Late Jurassic of northern Germany could not be confirmed. Some teeth of this study resemble specimens described as pertaining to Carcharodontosauria (morphotype A) and Abelisauridae (morphotype K). This interpretation is however, not supported by discriminant function analysis and cladistic analysis. Two smaller morphotypes (N and Q) differ only in some probably size-related characteristics from larger morphotypes (B and C) and could well represent juveniles of adult specimens. The similarity of the northern German theropods with groups from contemporaneous localities suggests faunal exchange via land-connections in the Late Jurassic between Germany, Portugal and North America.

  16. Multivariate and Cladistic Analyses of Isolated Teeth Reveal Sympatry of Theropod Dinosaurs in the Late Jurassic of Northern Germany

    Science.gov (United States)

    Gerke, Oliver; Wings, Oliver

    2016-01-01

    Remains of theropod dinosaurs are very rare in Northern Germany because the area was repeatedly submerged by a shallow epicontinental sea during the Mesozoic. Here, 80 Late Jurassic theropod teeth are described of which the majority were collected over decades from marine carbonates in nowadays abandoned and backfilled quarries of the 19th century. Eighteen different morphotypes (A—R) could be distinguished and 3D models based on micro-CT scans of the best examples of all morphotypes are included as supplements. The teeth were identified with the assistance of discriminant function analysis and cladistic analysis based on updated datamatrices. The results show that a large variety of theropod groups were present in the Late Jurassic of northern Germany. Identified specimens comprise basal Tyrannosauroidea, as well as Allosauroidea, Megalosauroidea cf. Marshosaurus, Megalosauridae cf. Torvosaurus and probably Ceratosauria. The formerly reported presence of Dromaeosauridae in the Late Jurassic of northern Germany could not be confirmed. Some teeth of this study resemble specimens described as pertaining to Carcharodontosauria (morphotype A) and Abelisauridae (morphotype K). This interpretation is however, not supported by discriminant function analysis and cladistic analysis. Two smaller morphotypes (N and Q) differ only in some probably size-related characteristics from larger morphotypes (B and C) and could well represent juveniles of adult specimens. The similarity of the northern German theropods with groups from contemporaneous localities suggests faunal exchange via land-connections in the Late Jurassic between Germany, Portugal and North America. PMID:27383054

  17. CIFCA Delegation Visits Brazil and Argentina

    Institute of Scientific and Technical Information of China (English)

    Wang; Bo

    2014-01-01

    <正>At the invitation of the UNALE(National Union of State Legislatures)of Brazi land La Plata City of Argentina,the China International Friendship Cities Association(CIFCA)Delegation,led by Vice President Hu Sishe,visited the two countries from May 4 to 13,during which it attended the 18th Conference of UNALE(18th CNLE)in Brasilia,the Brazilian capital.Broad Attendance at CNLE The CNLE,an annual event sponsored by the UNALE,seeks to promote

  18. Clientelism and Political Control in Rural Argentina

    Directory of Open Access Journals (Sweden)

    Fernando Landini

    2012-07-01

    Full Text Available Scholarship on clientelism frequently addresses political clientelism using strong ideological presuppositions and/or neglecting its subjective dimension. In this article I explore political clientelism in a rural community of the province of Formosa, Argentina from the peasants' point of view. The results suggest that peasants consider the clientelist relation as one that recognizes their personal needs, while the bureaucracy of the state does not. Thus, they perceive clientelist ties as legitimate, criticizing only the fact that the provision of resources by patrons takes place only during elections.

  19. Sexual Politics and Religious Actors in Argentina

    Directory of Open Access Journals (Sweden)

    Mario Pecheny

    2016-12-01

    Full Text Available This article examines the role of religious actors in sexual politics in Argentina. Sexual politics has become a critical battlefield when it comes to the role of religion in the Argentinean liberal-democratic regime, while gender and sexuality have been the main political targets of religious institutions since the 1980s and 1990s. In this context, progressive legislation on gender, sexual, and reproductive rights was passed, including same-sex marriage and the recognition of transgender identities, despite the opposition of the Catholic Church. Paradoxically, abortion remains largely illegal, allowed only in exceptional circumstances.

  20. Aedes aegypti resistance to temephos in Argentina.

    Science.gov (United States)

    Seccacini, Emilia; Lucia, Alejandro; Zerba, Eduardo; Licastro, Susana; Masuh, Hector

    2008-12-01

    Monitoring of resistance of Aedes aegypti to temephos was implemented in the provinces of Formosa and Misiones, Argentina, as a response to the need to improve the vigilance for the dengue vector in areas of high risk of dengue. Eggs collected in each locality were reared, and susceptibility to temephos was assayed using larval bioassays. A weak decrease in susceptibility of larvae to temephos was observed in Clorinda and Puerto Iguazú, indicating an incipient resistance with a resistance ratio of 3. No control failures have been observed yet, and this program should allow the early detection of a real problem in our country.

  1. Payenia volcanic province, southern Mendoza, Argentina

    DEFF Research Database (Denmark)

    Søager, Nina; Holm, Paul Martin; Llambias, Eduardo Jorge

    2013-01-01

    The Pleistocene to Holocene Payenia volcanic province is a backarc region of 60,000 km2 in Mendoza, Argentina, which is dominated by transitional to alkaline basalts and trachybasalts. We present major and trace element compositions of 139 rocks from this area of which the majority are basaltic...... basalts, trace element variations suggest a significant contribution from lower crustal melts, possibly up to 70% in the most extreme cases. The contaminating lower crustal rocks must have been depleted mafic rocks with a plagioclase component. The extensive melting of lower crust is probably related...

  2. Taxes and landowners in Argentina: an overview

    OpenAIRE

    Sánchez Román, José Antonio

    2014-01-01

    En este artículo se ofrece un balance de lo que sabemos –y de lo que aún desconocemos- sobre la historia de la relación entre los impuestos y los productores rurales en la Argentina contemporánea. Se lleva a cabo un recorrido por la historiografía sobre los impuestos al mundo agrario en los siglos XIX y XX tanto en el plano nacional como en el provincial y se señalan los aspectos que aún necesitan mayor investigación en este campo. This article provides an overview of our knowledge on the ...

  3. Middle matching mining algorithm

    Institute of Scientific and Technical Information of China (English)

    GUO Ping; CHEN Li

    2003-01-01

    A new algorithm for fast discovery of sequential patterns to solve the problems of too many candidate sets made by SPADE is presented, which is referred to as middle matching algorithm. Experiments on a large customer transaction database consisting of customer_id, transaction time, and transaction items demonstrate that the proposed algorithm performs better than SPADE attributed to its philosophy to generate a candidate set by matching two sequences in the middle place so as to reduce the number of the candidate sets.

  4. Late Jurassic Crustal Thickening in the Mesozoic Arc of Ecuador and Colombia: Implications on the Evolution of Continental Arcs.

    Science.gov (United States)

    Vanegas, J.; Cardona, A.; Blanco-Quintero, I.; Valencia, V.

    2014-12-01

    The tectonic evolution of South America during the Jurassic is related to the subduction of the Farallon plate and the formation of a series of continental arcs. In the northern Andes such arcs have been considered as controlled by extensional dominated tectonics. Paleomagnetic constraints have also suggested that between the Early and Late Jurassic several crustal domains were translate along the continental margin in association with strain partitioning in the convergent margin. A review of the character of the Salado terrane in the Cordillera Real of Ecuador indicates that it includes extensively deformed and metamorphosed volcano-sedimentary rocks that have achieved a greenschist to amphibolite facies event with chloritoid and garnet. This rocks are tightly associated with a ca. 143 Ma syn-tectonic granodiorite to monzogranite batholith that is also extensively milonitized.A similar Late Jurassic crustal thickening event that apparently affected volcano-sedimentary rocks have been also recently suspected in the Central Cordillera of the Colombian Andes in association with Jurassic plutonic rocks (Blanco-Quintero et al., 2013) It is therefore suggested that during the Late Jurassic the Northern Andes experienced significant contractional tectonics. Such crustal thickening may be related to either the active subduction setting were the crustal slivers formed in relation to oblique convergence are transfered and re-accreted to the margin and triggered the deformational event or to a collisional event associated to the arrival of an allocthonous terrane. New geochronological constraints on the metamorphic evolution and precise understanding on the relations between magmatism and deformation are going to be obtain in the Salado Terrane to appropriately test this hypothesis and contribute to the understanding of the extensional to compressional tectonic switching in continental arcs. Blanco-Quintero, I. F., García-Casco, A., Ruíz, E. C., Toro, L. M., Moreno, M

  5. The Emergence of Pelagic Carbonate Production by Nannoplankton in The Early Jurassic

    Science.gov (United States)

    Mattioli, E.; Pittet, B.; Suan, G.; Sucheras-Marx, B.; Reggiani, L.; Planck, J.

    2008-12-01

    Coccolithophores are among the main carbonate producers in today's Oceans. They participate to the organic-carbon pump and carbonate counter-pump at the same time, and therefore have a fundamental role in the carbon cycle. In this regard, the first occurrence and subsequent diversification of calcareous nannoplankton and in particular of coccolithophorids (225-65 Mya) likely had a major impact on biogeochemical cycles and the regulation of pCO2 in the atmosphere/hydrosphere. Nevertheless, both causes and consequences of the emergence of calcareous nannoplankton between the Late Triassic and the Early Jurassic remain poorly understood. In order to address the possible relationships between the early diversification of coccolithopororids and the evolution of atmospheric CO2 conditions, we performed a quantitative micropaleontological study in the well-exposed sections outcropping along the west coast of Portugal, spanning the entire Lower Jurassic. The accumulation rates of pelagic carbonates were reconstructed using the absolute abundances and size estimates of the most important pelagic carbonate producers as well as the cyclostratigraphic calibration of the studied successions. Our results show that nannofossil absolute abundance, although fluctuating in the Early Jurassic, increased by discrete steps. The first step (up to 0.2 billion of nannofossils per gram of rock) occurred at the base of the Late Pliensbachian and coincided with the deposition of organic matter-rich sediments. A second, more important increase is recorded at the Pliensbachian/Toarcian transition (-183 Mya), when absolute abundance attained values of 1.1 billion of nannofossils per gram of rock. These abundances are comparable to the record of surface sediments deposited under oligotrophic conditions. The following decrease in coccolithophorids observed during the Early Toarcian oceanic anoxic event is particularly intriguing. The dramatic decrease or loss of biocalcification potential could

  6. Chemo- and biostratigraphy of the Late Jurassic from the Lower Saxony Basin, Northern Germany

    Science.gov (United States)

    Erbacher, Jochen; Luppold, Friedrich Wilhelm; Heunisch, Carmen; Heldt, Matthias; Caesar, Sebastian

    2013-04-01

    The upper Jurassic (Oxfordian to Tithonian) sediments of the Lower Saxony Basin (Northern Germany) comprises a succession of limestones, marlstones and claystones deposited in a shallow marine to lacustrine epicontinental basin situated between the Tethys and the Sub-Boreal seas. Both, the depositional environment and the palaeogeographically isolated position strongly compromise a chronostratigraphic dating of the regional lithostratigraphical and biostratigraphical units. In order to obtain a stratigraphic standard section for the Late Jurassic of the Lower Saxony Basin we drilled a 325 m long core (Core Eulenflucht 1) covering the lower part of the Berriasian (Wealden 2-3 of the Bückeburg Formation) to the lower Oxfordian (Heersum Formation). A compilation with a section outcropping in an active quarry 2 km north of the drill site resulted in a 340 m long section reaching down to the late Callovian (Ornatenton Formation) . Ammonites have only been described in the lowermost, Callovian part of the section. Investigations of benthic foraminifers, ostracods as well as palynology, however, allowed for a rather detailed biozonation of the core. These data indicate the stratigrapical completeness of the section when compared to the regional stratigraphic data of the Lower Saxony Basin. Due to the lack of ammonites in Late Jurassic part of the section, which would have allowed for a correlation with Tethyan successions, high resolution stable carbon isotope data have been produced from bulk rock carbonate. Even though most of the data derive from shallow marine, rather coarse grained carbonates, such as ooliths and floatstones the resulting carbon isotope curve is surprisingly clean with only little "noise" in the upper part (early Tithonian?) of the measured succession. The curve clearly shows some distinctive features reported from biostratigraphically well-dated carbon isotope records of the Northern Tethys (e.g. Bartolini et al., 2003, Padden et al., 2002, Rais et

  7. Emplacement of the Jurassic Mirdita ophiolites (southern Albania): evidence from associated clastic and carbonate sediments

    Science.gov (United States)

    Robertson, Alastair H. F.; Ionescu, Corina; Hoeck, Volker; Koller, Friedrich; Onuzi, Kujtim; Bucur, Ioan I.; Ghega, Dashamir

    2012-09-01

    Sedimentology can shed light on the emplacement of oceanic lithosphere (i.e. ophiolites) onto continental crust and post-emplacement settings. An example chosen here is the well-exposed Jurassic Mirdita ophiolite in southern Albania. Successions studied in five different ophiolitic massifs (Voskopoja, Luniku, Shpati, Rehove and Morava) document variable depositional processes and palaeoenvironments in the light of evidence from comparable settings elsewhere (e.g. N Albania; N Greece). Ophiolitic extrusive rocks (pillow basalts and lava breccias) locally retain an intact cover of oceanic radiolarian chert (in the Shpati massif). Elsewhere, ophiolite-derived clastics typically overlie basaltic extrusives or ultramafic rocks directly. The oldest dated sediments are calpionellid- and ammonite-bearing pelagic carbonates of latest (?) Jurassic-Berrasian age. Similar calpionellid limestones elsewhere (N Albania; N Greece) post-date the regional ophiolite emplacement. At one locality in S Albania (Voskopoja), calpionellid limestones are gradationally underlain by thick ophiolite-derived breccias (containing both ultramafic and mafic clasts) that were derived by mass wasting of subaqueous fault scarps during or soon after the latest stages of ophiolite emplacement. An intercalation of serpentinite-rich debris flows at this locality is indicative of mobilisation of hydrated oceanic ultramafic rocks. Some of the ophiolite-derived conglomerates (e.g. Shpati massif) include well-rounded serpentinite and basalt clasts suggestive of a high-energy, shallow-water origin. The Berriasian pelagic limestones (at Voskopoja) experienced reworking and slumping probably related to shallowing and a switch to neritic deposition. Mixed ophiolite-derived clastic and neritic carbonate sediments accumulated later, during the Early Cretaceous (mainly Barremian-Aptian) in variable deltaic, lagoonal and shallow-marine settings. These sediments were influenced by local tectonics or eustatic sea

  8. Petrogenesis and tectonic implications of Early Jurassic volcanic rocks of the Raohe accretionary complex, NE China

    Science.gov (United States)

    Wang, Zhi-Hui; Ge, Wen-Chun; Yang, Hao; Bi, Jun-Hui; Ji, Zheng; Dong, Yu; Xu, Wen-Liang

    2017-02-01

    The Raohe accretionary complex, located at the border between the Russian Far East and Northeastern China, is a significant part of the western Pacific Oceanic tectonic regime. Due to lack of precise age and geochemical constraints, the tectonic setting and petrogenesis of the magmatic rocks in this area remain undefined, resulting in debate about crustal growth mechanisms and subduction-related accretionary processes in Northeastern China. Here, we report whole-rock major and trace element and Sr-Nd isotope data, together with zircon U-Pb ages and in situ zircon Hf isotope data for calc-alkaline andesites, dacites, rhyolites, rhyolitic crystal tuffs, Nb-enriched andesites and basaltic andesites, and high-Mg andesites of the Raohe accretionary complex in NE China. Samples were collected from Late Triassic to Early Jurassic strata. However, geochronological results in this study indicated that the studied magmatism occurred in the Early Jurassic (187-174 Ma). The calc-alkaline volcanic rocks possess geochemical characteristics typical of arc magmas that form at active continental margins, such as moderate enrichments in large ion lithophile elements (LILEs) and light rare earth elements (LREEs), and depletions in high field strength elements (HFSEs). They have positive εHf(t) values of +3.4 to +10.6 and relatively high (87Sr/86Sr)i values of 0.7047-0.7102. While the Nb-enriched andesites and basaltic andesites have higher TiO2, Hf, Nb, and Zr contents and higher Nb/Ta (24.0-87.6), Nb/U (11.9-75.9), (Nb/Th)PM (0.67-2.70), and (Nb/La)PM (1.95-5.00) ratios than typical arc basalts. They have negative εNd(t) values (-5.5 to -6.0) and relatively variable (87Sr/86Sr)i values of 0.7047-0.7114, suggesting an origin via the partial melting of mantle wedge peridotite that had been metasomatized by slab-derived melt. The high-Mg volcanic rocks, characterized by high MgO and Mg#, TiO2, Al2O3, Cr, Ni, (La/Yb)N and (La/Sm)N, but low Ba/Th ratios, are geochemically similar to

  9. Fostering a Middle Class

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Though there is no official definition of "middle class" in China, the tag has become one few Chinese people believe they deserve anyway.In early August, the Chinese Academy of Social Sciences released a report on China’s urban development,

  10. Middle East Reform Halts

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The chaos in Iraq poses a great threat to the U.S. plan in the Middle East While the fighting between Israel and Lebanon-based Hezbollah becomes fiercer, security in Iraq also keeps deteriorating, making the region a petrol can that may blow up anytime.

  11. Utopia Middle School

    Science.gov (United States)

    Cloud, Michelle

    2006-01-01

    The following excerpt allows the reader to briefly peer into an ideal school setting: For the purposes of this paper, the fictitious school will be named Utopia Middle School or U.M.S. U.M.S embodies and exemplifies the perfect school. At U.M.S., the campus administrators perform at a level of excellence that motivates, empowers and supports all…

  12. Model Middle Schools

    Science.gov (United States)

    Shapiro, Arthur; And Others

    1973-01-01

    Provides three models as approaches to organizing the middle school in a variety of exciting ways: (1) an oscillating system, where students in communities move between basic studies and related arts and physical education, (2) an immersion system, where students in communities spend full time moving between interdisciplinary areas, and (3) a…

  13. Derechos humanos y sexualidad en la Argentina

    Directory of Open Access Journals (Sweden)

    Mario Pecheny

    2006-12-01

    Full Text Available Este artículo presenta un panorama de la situación de los derechos que tienen que ver con la sexualidad, en la Argentina contemporánea. Basándose principalmente en la legislación positiva, se presenta en primer lugar una síntesis del sistema legal y político, resumiendo a continuación el proceso de inclusión de los derechos sexuales, sobre todo desde 1983, cuando se recuperó la democracia. Las temáticas abordadas son: igualdad civil y conyugalidad, orientación sexual e identidad de género, reproducción, aborto, violencia de género y violencia sexual, VIH/sida, y explotación y trabajo sexual. El artículo concluye con una reflexión sobre las principales deudas pendientes.This paper presents an overview of the situation concerning the rights related to sexuality in contemporary Argentina. Based specially on the positive legislation, it is primarily presented a synthesis of the legal and political system. Next, the paper summarizes the process of inclusion of the sexual rights, mainly since 1983, when democracy has been recovered. The following issues are addressed: civil equality and conjugality; sexual orientation and gender identity; reproduction; abortion; gender a sexual violence; HIV/Aids; and exploitation and sexual work. The paper ends with a consideration about the still remaining doubts.

  14. [Dengue vaccines. A reality for Argentina?].

    Science.gov (United States)

    Orellano, Pablo W; Salomón, Oscar D

    2016-01-01

    Dengue outbreaks have occurred yearly in Argentina since 1998. A number of candidate vaccines have been tested in endemic countries. The most advanced one was licensed in three countries of Latin America for children over 9 years of age. In the present article the benefits and drawbacks of these vaccines as well as the challenges for the implementation of a vaccination strategy in Argentina are discussed. Furthermore, a risk stratification strategy with new criteria and a multidisciplinary vision is suggested as a possible path for the assessment of the pertinence of a vaccination program in areas showing the highest risk of dengue transmission and/or for people at the greatest risk of developing severe dengue. It is also suggested that the definition regarding the status of endemicity should take into account the local realities. Finally, this paper proposes a broad discussion on the evidences, the expected impact and instrumental aspects that would be involved in the incorporation of a dengue vaccine, marketed or in development, into the national immunization program, and especially which subpopulation should be targeted for the immunization strategy to be cost-effective.

  15. Yugoslav teachers in Argentina 1939-1944

    Directory of Open Access Journals (Sweden)

    Stefanović-Banović Milesa

    2014-01-01

    Full Text Available In this paper we present reports of Yugoslav teachers who held classes to immigrants in Argentina 1939-1944, organized by the government of Kingdom of Yugoslavia. Teachers’ reports to Yugoslav Embassy in Buenos Aires testify of Kingdom of Yugoslavia efforts to oppose assimilation and promote and strengthen “Yugoslav national unity”. The reports also describe general social circumstances of Yugoslav immigrants, show various details from their everyday life and contain valuable data on numerous political, economic, social and cultural problems of this diaspora in Argentina and their relationship with motherland. We believe that archive materials presented in this paper opens numerous questions which could be topics of separate researches. Some of them could be the following: To which extent the teachers’ reports represented the actual situation and to which they were shaped to match policy and expectations of Kingdom of Yugoslavia? What was the actual influence of teachers to spreading the “national unity” among immigrants? Have their work left trace in Yugoslav diaspora and in which way? Beside all of the open issues, it is certain that teachers’ reports contain valuable data on immigrants’ everyday life, curriculum, schooling conditions, relationship with motherland, etc. [Projekat Ministarstva nauke Republike Srbije, br. 47016: Interdisciplinarno istraživanje kulturnog i jezičkog nasleđa Srbije. Izrada multimedijalnog internet portala "Pojmovnik srpske kulture"

  16. Oil and nationalism in Argentina: a history

    Energy Technology Data Exchange (ETDEWEB)

    Solberg, C.E.

    1979-01-01

    This case study of Yacimientos Petroliferos Fiscales, the world's first state-owned oil company, traces the development of Argentina's nationalistic petroleum policy from the discovery of oil on state-owned land in 1907 to the present. The focus is on the period prior to 1930, when the institutions and ideologies that have shaped Argentine petroleum affairs became firmly established. A final chapter summarizes developments since 1930, with emphasis on the impact the Argentine experience has had on other oil-producing countries in Latin America. Prior to World War I, Argentine governments gave little attention to the development of petroleum resources, but the wartime economic crisis demonstrated to many prominent political figures the necessity of shifting from dependence on foreign capital and imported fuel toward greater economic self-sufficiency. A key aspect of this new policy was the founding in 1922 of the state oil agency, YPF, which gradually wrested control of oil resources from the provinces in order to establish a vertically integrated, national petroleum industry. Because of its power and influence, YPF survived the 1930 revolution, became the largest economic enterprise in Argentina, and emerged as the very symbol of national economic independence.

  17. Overview and perspectives for Open Access development in Argentina

    Directory of Open Access Journals (Sweden)

    Sandra Miguel

    2013-04-01

    Full Text Available This paper provides an overview and perspectives for development of the Open Access movement in Argentina, within the global and regional (Latin American context. It outlines the evolution and current state of initiatives around the two main approaches to Open Access, the golden and green roads. The main Open Access policies and support of OA movement by governments in Latin American region, and particularly in Argentina, are highlighted, while recent studies on publishing practices and authors’ positions regarding Open Access are presented. The paper concludes that the prospects for development of OA in Argentina, both through golden and green roads are favorable, with their strengths and shortcomings

  18. Fusarium temperatum and Fusarium subglutinans isolated from maize in Argentina.

    Science.gov (United States)

    Fumero, María Verónica; Reynoso, María Marta; Chulze, Sofía

    2015-04-16

    Fusarium temperatum and Fusarium subglutinans isolated from the Northwest region (NOA region) of Argentina were characterized using a polyphasic approach based on morphological, biological and molecular markers. Some interfertility between the species was observed. The phylogenetic analysis showed that the two species represented two clades strongly supported by bootstrap values. The toxigenic profile of the strains was also determined. F. temperatum strains were fusaproliferin and beauvericin producers, and only some strains were fumonisin B1 producers. All F. subglutinans strains produced fusaproliferin but none produced beauvericin, indicating a potential toxicological risk from maize harvested in the NOA region of Argentina. This study provides new information about F. temperatum isolated from maize in Argentina.

  19. Horizontalidad, autogestión y protagonismo en Argentina

    Directory of Open Access Journals (Sweden)

    Marina Sitrin

    2010-04-01

    Full Text Available Este artículo trata los movimientos sociales autónomos que surgieron después de la crisis económica y la posterior rebelión popular en Argentina en diciembre de 2001. Los movimientos autónomos en la Argentina, como tantos movimientos en el mundo de hoy, son movimientos basados en la creación de nuevas relaciones sociales y comunidades ahora, al mismo tiempo que proyectan nuevas sociedades y las relaciones en y para el futuro. Son movimientos con una concepción diferente del tiempo y el espacio. Son movimientos que entienden lo individual y lo colectivo como vinculados entre sí.Hay mucho en común entre la experiencia en la Argentina y las prácticas e ideas anarquistas. Eso no significa que los que están creando nuevas relaciones y comunidades en la Argentina sean anarquistas. Lo que este artículo intenta hacer es basarse en las experiencias de los movimientos sociales argentinos para iniciar una reflexión sobre las prácticas e ideas que los anarquistas pueden prestar a los distintos movimientos y comunidades autónomas; y, a su vez, sobre lo que los movimientos autónomos en la Argentina puede dar a las ideas y prácticas anarquistas.Palabras Clave: movimientos sociales, rebelión popular, Argentina, Anarquismo, movimientos autónomos_____________________ABSTRACT:This article discusses the autonomous social movements that arose after the economic crisis and subsequent popular rebellion in Argentina in December of 2001. The autonomous movements in Argentina, as so many movements around the world today, are movements based on creating new social relationships and communities now, while simultaneously creating new societies and relationships in and for the future. They are movements with a different conception of time and place. They are movements that see the individual and the collective as linked to one another.There is a great deal in common with the experience in Argentina and anarchist practices and ideas. That does not make

  20. A Jurassic stem pleurodire sheds light on the functional origin of neck retraction in turtles

    Science.gov (United States)

    Anquetin, Jérémy; Tong, Haiyan; Claude, Julien

    2017-01-01

    Modern turtles are composed of two monophyletic groups, notably diagnosed by divergent neck retraction mechanisms. Pleurodires (side-necked turtles) bend their neck sideways and protect their head under the anterior margin of the carapace. Cryptodires (hidden-necked turtles) withdraw their neck and head in the vertical plane between the shoulder girdles. These two mechanisms of neck retraction appeared independently in the two lineages and are usually assumed to have evolved for protective reasons. Here we describe the neck of Platychelys oberndorferi, a Late Jurassic early stem pleurodire, and find remarkable convergent morphological and functional similarities with modern cryptodires. Partial vertical neck retraction in this taxon is interpreted to have enabled fast forward projection of the head during underwater prey capture and offers a likely explanation to the functional origin of neck retraction in modern cryptodires. Complete head withdrawal for protection may therefore have resulted from an exaptation in that group. PMID:28206991