Cenomanian-Turonian high-resolution biostratigraphy of north-eastern Mexico and its correlation with the GSSP and Europe     

Christina Ifrim  Wolfgang Stinnesbeck 《Cretaceous Research》2008,29(5-6):943

Thin-bedded and millimetrically laminated platy marly limestone quarried near Vallecillo, north-eastern Mexico, contains abundant excellently preserved marine fossils. Planktic foraminifers, inoceramids, and ammonites occur throughout the 7.7-m-thick section of this plattenkalk and provide a precise and detailed biostratigraphic zonation from the uppermost Cenomanian to early Turonian, with a mixed assemblage of Tethyan and Western Interior Seaway faunal elements. Five species of inoceramids are present and described herein: Inoceramus pictus pictus, Mytiloides hattini, M. puebloensis, M. goppelnensis, and M. kossmati. The faunal characteristics of the Vallecillo fossil assemblage combined with the monotonous lithology are favourable attributes for correlation with the GSSP at Pueblo, Colorado, and the Eastbourne section in southern England. The first appearances (FAs) of Watinoceras and Mammites nodosoides are considered approximately isochronous and thus suited for long-distance correlation. In contrast, the FAs of Pseudaspidoceras flexuosum, Fagesia catinus, and Helvetoglobotruncana helvetica are clearly diachronous. The range of M. kossmati needs further evaluation.  相似文献   

Sédimentologie et paléontologie des paléoenvironnements côtiers rupéliens de la Molasse marine rhénane dans le Jura suisse     

Laurent Picot  Damien Becker  Lionel Cavin  Claudius Pirkenseer  Frédéric Lapaire  Gaëtan Rauber  Peter A. Hochuli  Silvia Spezzaferri  Jean-Pierre Berger 《Swiss Journal of Geoscience》2008,101(2):483-513

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Miocene emplacement and rapid cooling of the Pohorje pluton at the Alpine-Pannonian-Dinaridic junction,Slovenia     

László I. Fodor  Axel Gerdes  István Dunkl  Balázs Koroknai  Zoltán Pécskay  Mirka Trajanova  Péter Horváth  Marko Vrabec  Bogomir Jelen  Kadosa Balogh  Wolfgang Frisch 《Swiss Journal of Geoscience》2008,101(1):255-271

New laser ablation-inductive coupled plasma-mass spectrometry U-Pb analyses on oscillatory-zoned zircon imply Early Miocene crystallization (18.64 ± 0.11 Ma) of the Pohorje pluton at the southeastern margin of the Eastern Alps (northern Slovenia). Inherited zircon cores indicate two crustal sources: a late Variscan magmatic population (~270–290 Ma), and an early Neoproterozoic one (850–900 Ma) with juvenile Hf isotope composition close to that of depleted mantle. Initial εHf of Miocene zircon points to an additional, more juvenile source component of the Miocene magma, which could be either a juvenile Phanerozoic crust or the Miocene mantle. The new U-Pb isotope age of the Pohorje pluton seriously questions its attribution to the Oligocene age ‘Periadriatic’ intrusions. The new data imply a temporal coincidence with 19–15 Ma magmatism in the Pannonian Basin system, more specifically in the Styrian Basin. K-Ar mineral- and whole rock ages from the pluton itself and cogenetic shallow intrusive dacitic rocks (~18–16 Ma), as well as zircon fission track data (17.7–15.6 Ma), gave late Early to early Middle Miocene ages, indicating rapid cooling of the pluton within about 3 Million years. Medium-grade Austroalpine metamorphics north and south of the pluton were reheated and subsequently cooled together. Outcrop- and micro scale structures record deformation of the Pohorje pluton and few related mafic and dacitic dykes under greenschist facies conditions. Part of the solidstate fabrics indicate E–W oriented stretching and vertical thinning, while steeply dipping foliation and NW–SE trending lineation are also present. The E–W oriented lineation is parallel to the direction of subsequent brittle extension, which resulted in normal faulting and tilting of the earlier ductile fabric at around the Early / Middle Miocene boundary; normal faulting was combined with strike-slip faulting. Renewed N–S compression may be related to late Miocene to Quaternary dextral faulting in the area. The documented syn-cooling extensional structures and part of the strike-slip faults can be interpreted as being related to lateral extrusion of the Eastern Alps and/or to back-arc rifting in the Pannonian Basin.  相似文献   

Sea level in the late Quaternary: patterns of variation and implications     

W. H. Berger 《International Journal of Earth Sciences》2008,97(6):1143-1150

Studies of oxygen isotopes in foraminifers from deepsea sediments yield information about rates of change of sea level, for hundreds of thousands of years with a resolution of roughly 1,000 years. The statistics regarding fluctuations for the late Quaternary (the last 900,000 years) suggest that a rise of 10 m per 1,000 years (1 m per century) is not unusual, even when the system resides within a warm stage, as now. Values near 2 m per century, while rare, are well within the range of a warm system, beyond the 5-percentile of the overall range. Once sea level is near +10 m, further rise becomes highly unlikely within the conditions of the late Quaternary, suggesting the presence of some kind of natural barrier; that is, lack of vulnerable ice. The present volume of ice generally considered vulnerable (Greenland and West-Antarctic ice sheet) adds up (roughly) to the observed limit.  相似文献   

Temporal variations and trends of CFC11 and CFC12 surface-water saturations in Antarctic marginal seas: Results of a regional ocean circulation model     

Christian B. Rodehacke  Wolfgang Roether  Hartmut H. Hellmer  Timothy Hall 《Deep Sea Research Part I: Oceanographic Research Papers》2010,57(2):175-198

The knowledge of chlorofluorocarbon (CFC11, CFC12) concentrations in ocean surface waters is a prerequisite for deriving formation rates of, and water mass ages in, deep and bottom waters on the basis of CFC data. In the Antarctic coastal region, surface-layer data are sparse in time and space, primarily due to the limited accessibility of the region. To help filling this gap, we carried out CFC simulations using a regional ocean general circulation model (OGCM) for the Southern Ocean, which includes the ocean–ice shelf interaction. The simulated surface layer saturations, i.e. the actual surface concentrations relative to solubility-equilibrium values, are verified against available observations. The CFC surface saturations driven by concentration gradients between atmosphere and ocean are controlled mainly by the sea ice cover, sea surface temperature, and salinity. However, no uniform explanation exists for the controlling mechanisms. Here, we present simulated long-term trends and seasonal variations of surface-layer saturation at Southern Ocean deep and bottom water formation sites and other key regions, and we discuss differences between these regions. The amplitudes of the seasonal saturation cycle vary from 22% to 66% and their long-term trends range from 0.1%/year to 0.9%/year. The seasonal surface saturation maximum lags the ice cover minimum by two months. By utilizing observed bottle data the full seasonal CFC saturation cycle can be determined offering the possibility to predict long-term trends in the future. We show that ignoring the trends and using instead the saturations actually observed can lead to systematic errors in deduced inventory-based formation rates by up to 10% and suggest an erroneous decline with time.  相似文献   

Spectral measurements of aerosol particle extinction in the 0.4–3.7 μm wavelength range, performed at Sagres with the IR‐RAD sun‐radiometer     

Vito Vitale  Claudio Tomasi  Wolfgang Von Hoyningen&#;huene  Ubaldo Bonafe  Stefano Marani  Angelo Lupi  Alessandra Cacciari  Pietro Ruggeri 《Tellus. Series B, Chemical and physical meteorology》2000,52(2):716-733

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Recent climatic trends and linkages to river discharge in Central Vietnam   总被引：1，自引：0，他引：1       下载免费PDF全文

Maxime Souvignet  Patrick Laux  Jim Freer  Hannah Cloke  Dang Quang Thinh  Tran Thuc  Johannes Cullmann  Alexandra Nauditt  Wolfgang‐Albert Flügel  Harald Kunstmann  Lars Ribbe 《水文研究》2014,28(4):1587-1601

In this study, change in rainfall, temperature and river discharge are analysed over the last three decades in Central Vietnam. Trends and rainfall indices are evaluated using non‐parametric tests at different temporal levels. To overcome the sparse locally available network, the high resolution APHRODITE gridded dataset is used in addition to the existing rain gauges. Finally, existing linkages between discharge changes and trends in rainfall and temperature are explored. Results are indicative of an intensification of rainfall (+15%/decade), with more extreme and longer events. A significant increase in winter rainfall and a decrease in consecutive dry days provides strong evidence for a lengthening wet season in Central Vietnam. In addition, trends based on APHRODITE suggest a strong orographic signal in winter and annual trends. These results underline the local variability in the impacts of climatic change at the global scale. Consequently, it is important that change detection investigations are conducted at the local scale. A very weak signal is detected in the trend of minimum temperature (+0.2°C/decade). River discharge trends show an increase in mean discharge (31 to 35%/decade) over the last decades. Between 54 and 74% of this increase is explained by the increase in precipitation. The maximum discharge also responds significantly to precipitation changes leading to a lengthened wet season and an increase in extreme rainfall events. Such trends can be linked with a likely increase in floods in Central Vietnam, which is important for future adaptation planning and management and flood preparedness in the region. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Interferometry basics in practice: Exercises     

Florentin Millour  Damien Sgransan  Jean-Philippe Berger  Gilles Duvert  Fabien Malbet 《New Astronomy Reviews》2008,52(2-5):208

The following exercises aim to learn the link between the object intensity distribution and the corresponding visibility curves of a long-baseline optical interferometer. They are also intended to show the additional constraints on observability that an interferometer has.This practical session is meant to be carried out with the ASPRO software, from the Jean-Marie Mariotti Center, but can also be done using other observation preparation software, such as viscalc from ESO.There are two main parts with series of exercises and the exercises corrections. The first one aims at understanding the visibility and its properties by practicing with simple examples, and the second one is about UV coverage.  相似文献   

Early Cretaceous rift-related volcanism in the Songliao Basin,NE China – A geochemical study     

Shuang-Qing Li  Yan Wang  Bo-Wen Fang  Jian-Feng He  Fukun Chen  Wolfgang Siebel 《International Geology Review》2019,61(1):39-55

Following the amalgamation of the Siberian and North China Cratons, NE China, as part of the Central Asian Orogenic Belt (CAOB), underwent Late Mesozoic lithospheric extension that was associated with volcanic activity. The Songliao Basin is the most important rift structure formed during these processes and contains voluminous volcanic rocks interlayered with sedimentary infill. Mafic-to-intermediate lavas are associated with felsic ones. This study focusses on the geochemical compositions of the less-widespread Early Cretaceous mafic-to-intermediate lavas in the Songliao Basin and compares them with the more abundant felsic rocks. Two mafic-to-intermediate magma series, one with alkaline and the other with sub-alkaline affinity, were identified. High MgO and Cr contents, low Th/Nb and La/Nb ratios, and variable but depleted Nd isotope compositions indicate that both magma suites were most likely formed by the melting of enriched upper mantle sources. Sub-alkaline mafic-to-intermediate rocks and I-type rhyolites define a co-genetic magma series. This rock suite was produced by the melting of subduction-modified lithospheric mantle and subsequent magma evolution as well as crustal melting during lithospheric extension. Alkaline mafic-to-intermediate rocks and A-type rhyolites form another co-genetic magma suite that was produced under within-plate conditions from an OIB-type mantle source, supposed to be the heterogeneous shallow asthenosphere and/or the lower lithosphere. Decompression partial melting of this mantle source requires a relatively thin lithosphere. The development of alkaline mafic rocks and A-type rhyolites as typical bimodal volcanic assemblage reflects that lithospheric thinning below the Songliao Basin reached its maximum, whereas basin rifting terminated afterwards.  相似文献   

Special issue on global perspectives on the aeronomy of the summer mesopause region     

Richard L. Collins  Scott M. Bailey  Uwe Berger  Franz-Josef Lübken  Aimee W. Merkel 《Journal of Atmospheric and Solar》2009,71(3-4):285-288

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