Magnetostratigraphy and Pliocene-Pleistocene boundary in Italy     

Claudio Arias  Augusto Azzaroli  Giulio Bigazzi  Francescopaolo Bonadonna 《Quaternary Research》1980,13(1):65-74

Analysis of some sedimentary series near Rome and comparison with other series in northern and southern Italy give evidence that Arctica islandica, considered a marker species for the beginning of the Pleistocene, appears during the Re´union paleomagnetic event (about 2 my ago). A period of erosion, called the Aullan erosional phase, is evident in the lower part of the late Villafranchian (= early Pleistocene, Olivola faunal unit).  相似文献   

Late Quaternary palaeohydrology of Lake Pergusa (Sicily,southern Italy) as inferred by stable isotopes of lacustrine carbonates     

Giovanni Zanchetta  Alessandra Borghini  Anthony E. Fallick  Francesco P. Bonadonna  Gabriello Leone 《Journal of Paleolimnology》2007,38(2):227-239

Ten meters of lacustrine deposits retrieved from Lake Pergusa (Sicily, southern Italy) were investigated through stable isotope composition (carbon and oxygen) of authigenic carbonate (calcareous muds) and freshwater shells. The core chronology was established through three AMS dates, and by correlation with a previously dated nearby core. Stable isotope data show that the lake water evolution was mainly dominated by evaporation. Between ca. 20 and 28 ka the recovered sediments have very high δ¹⁸O values, likely corresponding to very dry climatic conditions. The observed rapid oscillations in the δ¹⁸O of the recovered sediments during this period also suggest important climatic fluctuations. More humid conditions dominated during the Holocene period, with the wettest interval occurring between ca. 9000 and 3000 years BP. Late Holocene sediments represent a substantial return to drier conditions. The available pollen data from a nearby core substantially confirm this general climatic trend during the Holocene. The positive correlation between δ¹³C of the calcareous muds and carbonate content suggests that biological activity played a key role in the carbon isotope evolution of dissolved inorganic carbon. However, a clear climatic signal is not evident from the δ¹³C record.  相似文献   

An approach to the seismic design of steel structures based on cumulative damage criteria     

Giulio Ballio  Carlo A. Castiglioni 《地震工程与结构动力学》1994,23(9):969-986

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Inversion of Multiconfiguration Complex EMI Data with Minimum Gradient Support Regularization: A Case Study     

Deidda  Gian Piero  Díaz de Alba  Patricia  Rodriguez  Giuseppe  Vignoli  Giulio 《Mathematical Geosciences》2020,52(7):945-970

Mathematical Geosciences - Frequency-domain electromagnetic instruments allow the collection of data in different configurations, that is, varying the intercoil spacing, the frequency, and the...  相似文献   

Fission‐track dating of a tephra layer related to Poti‐Malal and Seguro drifts in the Río Grande basin,Mendoza, Argentina     

Lydia E. Espizua  Giulio Bigazzi  Pedro J. Iunes  Julio C. Hadler  Ana Maria Osorio 《第四纪科学杂志》2002,17(8):781-788

Two old drift units called Poti‐Malal and Seguro have been differentiated in the Río Grande basin based on relative‐age criteria, stratigraphical relationships, morphology and fission‐track dating. A tephra dated at 0.226 ± 0.025 Ma was deposited on the Poti‐Malal drift and underlies the Seguro outwash, which is inferred to equate with marine oxygen isotope stage 6. The stratigraphical position and age suggest that the tephra post‐dates the Poti‐Malal glaciation and that it is older than the Seguro drift. The Poti‐Malal glaciation must be at least as old as Early–Middle Pleistocene, and the Seguro glaciation is assigned to the penultimate glaciation. The tephra unit may have been deposited during marine oxygen isotope stage 7. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

Temporal variation in the water chemistry of northern Victoria Land lakes (Antarctica)     

Francesca Borghini  Andrea Colacevich  Tancredi Caruso  Roberto Bargagli 《Aquatic Sciences - Research Across Boundaries》2008,70(2):134-141

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From cylindrical to non‐cylindrical foreland basin: Pliocene–Pleistocene evolution of the Po Plain–Northern Adriatic basin (Italy)     

Chiara Amadori  Giovanni Toscani  Andrea Di Giulio  Francesco Emanuele Maesano  Chiara D&#x;Ambrogi  Manlio Ghielmi  Roberto Fantoni 《Basin Research》2019,31(5):991-1015

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A note on “overfishing”     

Giulio Pontecorvo   《Marine Policy》2008,32(6):1050-1052

The continuing public concern with overfishing ignores the underlying problems that face fishery mangers. Attention needs to be given to (1) the transitory nature of the ocean environment, (2) the natural variation in fish stocks, (3) the role of the fishing industry and market forces in fishery management, and (4) the failure to focus on what it is we most need from the oceans, in what form we need it, and at what price.  相似文献   

Hydrogeology of the Nurra Region, Sardinia (Italy): basement-cover influences on groundwater occurrence and hydrogeochemistry   总被引：2，自引：0，他引：2  

Giorgio Ghiglieri  Giacomo Oggiano  Maria Dolores Fidelibus  Tamiru Alemayehu  Giulio Barbieri  Antonio Vernier 《Hydrogeology Journal》2009,17(2):447-466

The Nurra district in the Island of Sardinia (Italy) has a Palaeozoic basement and covers, consisting of Mesozoic carbonates, Cenozoic pyroclastic rocks and Quaternary, mainly clastic, sediments. The faulting and folding affecting the covers predominantly control the geomorphology. The morphology of the southern part is controlled by the Tertiary volcanic activity that generated a stack of pyroclastic flows. Geological structures and lithology exert the main control on recharge and groundwater circulation, as well as its availability and quality. The watershed divides do not fit the groundwater divide; the latter is conditioned by open folds and by faults. The Mesozoic folded carbonate sequences contain appreciable amounts of groundwater, particularly where structural lows are generated by synclines and normal faults. The regional groundwater flow has been defined. The investigated groundwater shows relatively high TDS and chloride concentrations which, along with other hydrogeochemical evidence, rules out sea-water intrusion as the cause of high salinity. The high chloride and sulphate concentrations can be related to deep hydrothermal circuits and to Triassic evaporites, respectively. The source water chemistry has been modified by various geochemical processes due to the groundwater–rock interaction, including ion exchange with hydrothermal minerals and clays, incongruent solution of dolomite, and sulphate reduction.  相似文献   

Formal proposal for the Bathonian GSSP (Middle Jurassic) in the Ravin du Bès Section (Bas-Auran, SE France)     

Sixto R. Fernández-López  Giulio Pavia  Elisabetta Erba  Myett Guiomar  Maria H. Henriques  Roberto Lanza  Charles Mangold  Davide Olivero  Daniele Tiraboschi 《Swiss Journal of Geoscience》2009,102(2):271-295

The Bathonian Global Stratotype Section and Point (GSSP) is proposed at the base of limestone bed RB071 (bed 23 in Sturani 1967) in the Ravin du Bès Section (43° 57′ 38′′ N, 6° 18′ 55′′ E), Bas-Auran area, “Alpes de Haute Provence” French department. The Ravin du Bès Section, as formal candidate GSSP for the base of the Bathonian Stage, satisfies most of the requirements recommended by the International Commission on Stratigraphy: 1) The exposure extends over 13 m in thickness. At the Bajocian-Bathonian transition, no vertical (bio-, ichno- or tapho-) facies changes, condensation, stratigraphic gaps or hiatuses have been recorded. Structural complexity, synsedimentary and tectonic disturbances, or important alterations by metamorphism are not relevant constraints. 2) There is a well-preserved, abundant and diverse fossil record across the boundary interval, with key markers (ammonites and nannofossils) for worldwide correlation. The base of the Bathonian Stage and Zigzag Zone in Bas-Auran corresponds to the first occurrence level of Gonolkites convergens Buckman, which coincides with the first occurrence of Morphoceras parvum Wetzel. Calcareous nannofossils, as secondary global marker, are present in all beds and allow characterizing the Bajocian-Bathonian transition. 3) Regional analyses of sequence stratigraphy and manganese chemostratigraphy are available. Spectral gamma-ray data corroborate an Early Bathonian deepening half-cycle of second order. 4) The criteria of accessibility, conservation and protection are assured by the “Réserve Naturelle Géologique de Haute Provence”. The Cabo Mondego Section (Portugal) is suggested as the Bathonian auxiliary section and point (ASSP) within this GSSP proposal.  相似文献