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981.
Andrea Brogi Enrico Capezzuoli Riccardo Aqué Marilì Branca Mario Voltaggio 《International Journal of Earth Sciences》2010,99(6):1383-1398
Middle–Late Pleistocene tectonic activity has been inferred through studies on travertine deposits exposed in a tract of the
hinterland Northern Apennines. A detailed study on the relationships between tectonics and travertine deposition coupled with
230Th/234U age determination of travertines at Cava Oliviera quarry, located close to Serre di Rapolano village (southern Tuscany,
Northern Apennines), allowed us to recognise Pleistocene faults, whose activity has been referred to 157–24 ka, at least.
Travertine deposition was tectonically controlled by WSW-ENE striking, oblique and normal faults, associated to a main fault
(named as the Violante Fault). This structure dissected a regional normal fault (known as the Rapolano Fault) Early–Middle
Pliocene in age, which bounded the eastern side of the Pliocene Siena Basin, and gave rise to space accommodation for clayey
and sandy marine sediments. Hydrothermal circulation (and related travertine deposition) was favoured by the damaging enhancement
due to the fault–fault intersection. Tectonic activity has been also documented by deformation recorded by travertines, which
suggest a main tectonic event between 64 ± 5 and 40 ± 5 ka. The tectonic activity described for the study area agrees with
the Quaternary tectonic evolution documented in the surrounding areas (e.g. Mt. Amiata and Mt. Vulsini), as well as the Tyrrhenian
margin of the Central Apennines, indicating that a widespread tectonic activity affected the inner part of the Apennines until
the latest Quaternary. 相似文献
982.
Transpressional tectonics and nappe stacking along the Southern Variscan Front of Morocco 总被引:1,自引:0,他引:1
Andrea Cerrina Feroni Alessandro Ellero Marco G. Malusà Giovanni Musumeci Giuseppe Ottria Riccardo Polino Leonardo Leoni 《International Journal of Earth Sciences》2010,99(5):1111-1122
The Southern Variscan Front in the Tinerhir area involves Palaeozoic allochthonous units (Ouaklim and Tilouine units) thrust
onto the northern edge of the West African Craton during late Carboniferous time. Illite crystallinity data highlight an anchizonal
grade for the Ouaklim Unit, and a diagenesis-anchizone transition for the Tilouine Unit during deformation phase D1. The tectonic
stack is crosscut by major dextral reverse faults bounding E–W trending domains of dominant shortening deformation (central
domain) and strike-slip deformation (northern and southern domains), later segmented by a network of post-Variscan faults.
This complex deformation pattern is the result of kinematic partitioning of dextral transpression along the Southern Variscan
Front, coeval with the Neovariscan (300–290 Ma) oblique convergence observed at the scale of the whole Moroccan Variscides.
Partitioning of dextral transpression described in the Tinerhir area is consistent with dextral wrench faulting along the
Tizi n’ Test Fault, and with Appalachian-style south-directed thrusting in the Tinerhir and Bechar-Bou Arfa areas. 相似文献
983.
Yeşim İslamoğlu Mathias Harzhauser Martin Gross Gonzalo Jiménez-Moreno Stjepan Coric Andreas Kroh Fred Rögl Jan van der Made 《International Journal of Earth Sciences》2010,99(1):183-200
The Oligocene depositional history of the Thrace Basin documents a unique paleogeographic position at a junction between the
Western Tethys and the Eastern Paratethys. As part of the Tethys, shallow marine carbonate platforms prevailed during the
Eocene. Subsequently, a three-staged process of isolation started with the Oligocene. During the Early Rupelian, the Thrace
Basin was still part of the Western Tethys, indicated by typical Western Tethyan marine assemblages. The isolation from the
Tethys during the Early Oligocene is reflected by oolite formation and endemic Eastern Paratethyan faunas of the Solenovian
stage. The third phase reflects an increasing continentalisation of the Thrace Basin with widespread coastal swamps during
the Late Solenovian. The mollusc assemblages are predominated by mangrove dwelling taxa and the mangrove plant Avicennia is recorded in the pollen spectra. The final continentalisation is indicated by the replacement of the coastal swamps by
pure freshwater swamps and fluvial plains during the Late Oligocene (mammal zone MP 26). This paleogeographic affiliation
of the Thrace Basin with the Eastern Paratethys after ~32 Ma contrasts all currently used reconstructions which treat the
basin as embayment of the Eastern Mediterranean basin. 相似文献
984.
We investigated whether climate change results in long-term changes in phytoplankton biomass and phenology in a turbid eutrophic
coastal plain estuary. Changes in annual mean chlorophyll a (chla) concentrations were studied for the period 1978–2006 in the eutrophic and turbid macro-tidal Western Scheldt estuary. Three
stations were investigated: WS1, at the mouth of the estuary; station WS6, halfway up the estuary; and station WS11, near
the Dutch–Belgian border near the upstream end of the estuary. No significant long-term changes in yearly averaged chla concentrations were observed in WS1 and WS6, but in WS11 the phytoplankton biomass decreased considerably. This is most likely
due to an increase in grazing pressure as a result of an improvement in the dissolved oxygen concentrations. Spectral analyses
revealed a possible periodicity of 7 years in the mean chla which was related to periodicity in river discharge. We also observed strong phenological responses in the timing of the
spring/summer bloom which were related to a well-documented increase in the temperature in the estuary. The fulcrum, the center
of gravity or the day at which 50% of the cumulative chla was reached during the year, advanced by 1–2 days/year. A similar trend was observed for the month in which the maximum bloom
was observed, with the exception of station WS1. All stations showed an earlier initiation of the bloom, whereas the day at
which the phytoplankton bloom was terminated also moved forward in time excepted for WS11. As a result, the bloom length decreased
at station WS1, remained the same at station WS6, and increased at WS11. This complicated pattern in bloom phenology demonstrates
the complex nature of ecosystem functioning in estuaries. 相似文献
985.
Franco Mantovani Francisco Javier Gracia Pietro Domenico de Cosmo Andrea Suma 《Landslides》2010,7(1):69-74
This paper presents the preliminary results of a geomorphological survey of the Olvera area (Cadiz province, Betic Ranges,
Spain) and the use of the Geographic Information System (GIS) Open Source (OS) software plus Database Management System (DBMS)
for making available and distributing the landslide data over the Web. In the geomorphologic survey, different landforms have
been identified in the area, including structural, anthropogenic, fluvial, karst, and slope forms. In particular, the majority
of the slope forms are complex (from topple to rotational slides and falls), but there are also minor forms like debris flows
and mudslides. To manage geomorphological data, an Open Source GIS was used, which contained the following components: QuantumGIS,
System for Automated Geoscientific Analyses (SAGA), GIS and Geographic Resources Analysis Support System (GRASS), GIS for
Digital Elevation Model (DEM) generation. A key aim was to make the project-derived data available over the Web. This was
achieved using MapServer which allows for the representation of the derived geospatial data with pMapper providing the graphical
Web interface. Our study highlights the process dynamics of run-off erosion in Olvera derived through the use of advanced
computer-based mapping tools. The resulting map products and interpretations are available via the Internet. To date, derivative
maps have been produced to improve maintenance of roads and transport and of the construction of new infrastructure. 相似文献
986.
Andrea Cannata Gaetano Giudice Sergio Gurrieri Placido Montalto Salvatore Alparone Giuseppe Di Grazia Rocco Favara Stefano Gresta Marco Liuzzo 《Environmental Earth Sciences》2010,61(3):477-489
Large variations of the CO2 flux through the soil were observed between November 2002 and January 2006 at Mt. Etna volcano. In many cases, the CO2 flux was strongly influenced by changes in air temperature and atmospheric pressure. A new filtering method was then developed
to remove the atmospheric influences on soil CO2 flux and, at the same time, to highlight the variations strictly related to volcanic activity. Successively, the CO2 corrected data were quantitatively compared with the spectral amplitude of the volcanic tremor by cross correlation function,
cross-wavelet spectrum and wavelet coherence. These analyses suggested that the soil CO2 flux variations preceded those of volcanic tremor by about 50 days. Given that volcanic tremor is linked to the shallow (a
few kilometer) magma dynamics and soil CO2 flux related to the deeper (~12 km b.s.l.) magma dynamics, the “delayed similarity” between the CO2 flux and the volcanic tremor amplitude was used to assess the average speed in the magma uprising into the crust, as about
170–260 m per day. Finally, the large amount of CO2 released before the onset of the 2004–2005 eruption indicated a deep ingression of new magma, which might have triggered
such an eruption. 相似文献
987.
Simone Fontana Fadi H. Nader Sadoon Morad Andrea Ceriani Ihsan S. Al-Aasm 《Arabian Journal of Geosciences》2010,3(4):351-368
This diagenetic study (including fieldwork, petrographic, fluid inclusion, and stable isotope investigations) deals with the outcrop of Upper Permian–Lower Triassic carbonate rocks, which are equivalent to the Khuff Formation. The studied succession, which outcrops in the Ras Al Khaimah region, northern United Arab Emirates, comprises three formations, including the Bih, the Hagil, and the Ghail formations. The study focuses on unraveling the conditions and fluid compositions encountered during diagenesis of the succession. Emphasize is also made on linking diagenesis to major stratigraphic surfaces and to highlight reservoir property evolution and heterogeneity of the studied rocks. The evolution of fluids and related diagenetic products can be summarized as follows: (1) formation of near-surface to shallow burial, fine-crystalline dolomite (dolomite matrix) through pervasive dolomitization of carbonate sediments by modified marine pore waters; (2) formation of coarse-crystalline dolomite cement by highly evolved marine pore waters (13–23 wt.% NaCl eq.) at elevated temperatures (120–208°C), and (3) calcite cementation by highly saline fluid (20–23 wt.% NaCl eq.) at high temperature (170–212°C). A final calcite cement generation has been formed by the percolation of meteoric fluids during uplift. Fracture- and vug-filling diagenetic minerals are mainly restricted to the mid-Bih breccia marker level, suggesting preferential focused fluid flow through specific stratigraphic surfaces as well as along tectonic-related structures. Reservoir properties have been evolved as result of the interplay of the original sedimentary texture and the diagenetic evolution. Porosity is higher in the Bih Formation, which is dominated by dolomitized packstones and grainstones, than in the Hagil and Ghail formations, consisting mainly of dolomitized mudstones and wackestones. Image analyses were used to quantify the visual porosity in thin sections. The highest porosity values were measured in the Bih Formation, which is characterized by significant amounts of vug- and fracture-filling cements. This feature is attributed to the increase of porosity owing to substantial dissolution of abundant intergranular and vug-filling cements. In contrast, the Hagil and Ghail formations, which consist of finer-grained rock than the Bih Formation, were less cemented, and thus, the porosity enhancement by cement dissolution was insignificant. 相似文献
988.
989.
Remotely sensed soil moisture integration in an ecosystem carbon flux model. The spatial implication
Willem W. Verstraeten Frank Veroustraete Wolfgang Wagner Tom Van Roey Walter Heyns Sara Verbeiren Jan Feyen 《Climatic change》2010,103(1-2):117-136
While remote sensing is able to provide spatially explicit datasets at regional to global scales, extensive application to date has been found only in the reporting and verification of ecosystem carbon fluxes under the Kyoto Protocol. One of the problems is that new remote sensing datasets can be used only with models or data assimilation schemes adapted to include a data input interface dedicated to the type and format of these remote sensing datasets. In this study, soil water index data (SWI), derived from the ERS scatterometer (10-daily time period with a spatial resolution of 50 km), are integrated into the ecosystem carbon balance model C-Fix to assess 10-daily Net Ecosystem Productivity (NEP) patterns of Europe from the remote sensing perspective on an approximate 1-by-1 km2 pixel scale using NDVI-AVHRR data. The modeling performance of NEP obtained with and without the assimilation of remotely sensed soil moisture data in the carbon flux model C-Fix is evaluated with EUROFLUX data. Results show a general decrease of the RRMSE of up to 11 with an average of 3.46. C-Fix is applied at the European scale to demonstrate the potential of this ecosystem carbon flux model, based on remote sensing inputs. More specifically, the strong impact of soil moisture on the European carbon balance in the context of the Kyoto Protocol (anthropogenic carbon emissions) is indicated at the country level. Results suggest that several European countries shift from being a carbon sink (i.e., NEP > 1) to being a carbon source (i.e., NEP < 0) whether or not short-term water availability (i.e., soil moisture) is considered in C-Fix NEP estimations. 相似文献
990.
Yongkang Xue Fernando De Sales W. K.-M. Lau Aaron Boone Jinming Feng Paul Dirmeyer Zhichang Guo Kyu-Myong Kim Akio Kitoh Vadlamani Kumar Isabelle Poccard-Leclercq Natalie Mahowald Wilfran Moufouma-Okia Phillip Pegion David P. Rowell Jae Schemm Siegfried D. Schubert Andrea Sealy Wassila M. Thiaw Augustin Vintzileos Steven F. Williams Man-Li C. Wu 《Climate Dynamics》2010,35(1):3-27
This paper briefly presents the West African Monsoon (WAM) Modeling and Evaluation Project (WAMME) and evaluates WAMME general circulation models’ (GCM) performances in simulating variability of WAM precipitation, surface temperature, and major circulation features at seasonal and intraseasonal scales in the first WAMME experiment. The analyses indicate that models with specified sea surface temperature generally have reasonable simulations of the pattern of spatial distribution of WAM seasonal mean precipitation and surface temperature as well as the averaged zonal wind in latitude-height cross-section and low level circulation. But there are large differences among models in simulating spatial correlation, intensity, and variance of precipitation compared with observations. Furthermore, the majority of models fail to produce proper intensities of the African Easterly Jet (AEJ) and the tropical easterly jet. AMMA Land Surface Model Intercomparison Project (ALMIP) data are used to analyze the association between simulated surface processes and the WAM and to investigate the WAM mechanism. It has been identified that the spatial distributions of surface sensible heat flux, surface temperature, and moisture convergence are closely associated with the simulated spatial distribution of precipitation; while surface latent heat flux is closely associated with the AEJ and contributes to divergence in AEJ simulation. Common empirical orthogonal functions (CEOF) analysis is applied to characterize the WAM precipitation evolution and has identified a major WAM precipitation mode and two temperature modes (Sahara mode and Sahel mode). Results indicate that the WAMME models produce reasonable temporal evolutions of major CEOF modes but have deficiencies/uncertainties in producing variances explained by major modes. Furthermore, the CEOF analysis shows that WAM precipitation evolution is closely related to the enhanced Sahara mode and the weakened Sahel mode, supporting the evidence revealed in the analysis using ALMIP data. An analysis of variability of CEOF modes suggests that the Sahara mode leads the WAM evolution, and divergence in simulating this mode contributes to discrepancies in the precipitation simulation. 相似文献