Spatial association of mud volcano and sandstone intrusions,Boyadag anticline,western Turkmenistan          下载免费PDF全文

Davide Oppo  Rossella Capozzi 《Basin Research》2016,28(6):827-839

The mud volcano and sandstone intrusions complex occurring in the Boyadag anticline, western Turkmenistan, is the only well‐documented example of co‐existing, but not synchronous, mud volcanism and sand intrusion. Integrated field and laboratory evaluation investigates the spatial and genetic relations between the mud extrusion and the later sand intrusion. A sandstone dike and a pillar pierce mud volcano deposits on the crest of Boyadag anticline. Two more dikes occur near the escarpment caused by a crestal normal fault. The rising of mud and hydrocarbons from the Oligocene Maykop Fm. fed the mud volcano after the exposure of the Lower Pleistocene units at the core of the anticline. The main physical process that later led to sand fluidisation is identified as the progressive increase in pore fluid pressure, during a stage of reduced or null activity of the mud volcano, caused by the up‐dip migration of hydrocarbons from the deep basin into the Pliocene sandstone reservoir within the Boyadag anticline. The hydrocarbons generated in the source rock levels of the Maykop Fm., whereas the saline water involved in the sand fluidisation is identified as the connate water of the Pliocene Red Beds Fm. The pressure rise was responsible for the fracturing of the sealing units, already weakened by the crestal normal fault and the mud volcano feeding system. The sand intruded into sealing units and mud breccia deposits, also using the mud volcano conduit and the crestal normal fault as preferential pathways. During the present‐day background activity, the outcropping sandstone intrusions provide high permeability pathways for continuous fluid leakage, precluding the re‐establishment of high pressures in the reservoir.  相似文献   

Lithological control of land subsidence induced by groundwater withdrawal in new urban AREAS (Granada Basin,SE Spain). Multiband DInSAR monitoring          下载免费PDF全文

Davide Notti  Rosa María Mateos  Oriol Monserrat  Nùria Devanthéry  Tomás Peinado  Francisco Javier Roldán  Francisca Fernández‐Chacón  Jorge Pedro Galve  Francisco Lamas  Jose Miguel Azañón 《水文研究》2016,30(13):2317-2331

Ground subsidence in the southeastern border of the Granada Basin (SE Spain) has been studied using remote sensing techniques. Over the last decades, the region has experienced a huge urban expansion, which has caused a substantial increase in water supply requirements. Water needs are exclusively met by groundwater by means of numerous pumping wells, which exploit a confined detrital aquifer of alluvial fan deposits with a heterogeneous facies distribution. A general piezometric level decline (up to 50 m) has been recorded in the aquifer during the past 30 years that has induced the generation of a subsiding area with oval shape oriented WNW‐ESE just where the new urban areas and pumping wells are located. Subsidence has been monitored by exploiting synthetic aperture radar (SAR) images from ENVISAT (2003–2009) and Cosmo‐SkyMed (2011–2014). A new approach, which combines A‐DInSAR and small‐area persistent scatterer interferometry (PSI) analysis, has been applied obtaining a good accuracy regarding temporal and spatial dimension of the subsidence. ENVISAT data (2003–2009) reveal subsidence rates up to 10–15 mm/year, and Cosmo‐SkyMed (2011–2014) values slightly lower; up to 10 mm/year. Temporal variations in the subsidence velocity are in accordance with the rainfall pattern and piezometric fluctuations in the aquifer. The sector with highest rates of subsidence does not correspond to the area with more intense groundwater exploitation but to the area with greater presence of clays in the confining layer of the aquifer. There is a clear lithological control in the spatial distribution of the ground subsidence. This work integrates detailed geological and hydrogeological data with differential SAR interferometry monitoring with the aim to better understand subsidence processes in detrital aquifers with small‐scale heterogeneity. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Detection of Miocene saucer‐shaped sills (offshore Senegal) via integrated interpretation of seismic,magnetic and gravity data     

Sergio Rocchi  Alfredo Mazzotti  Michele Marroni  Luca Pandolfi  Paolo Costantini  Bertozzi Giuseppe  Davide di Biase  Francesco Federici  Papa Goumbo L 《地学学报》2007,19(4):232-239

The Atlantic margin offshore Senegal has been explored by seismic reflection and GRAV‐MAG surveys. High‐amplitude, laterally transgressive seismic reflectors are found to coincide with gravimetric and magnetic highs. Once seismic data are integrated with potential fields modelling, these reflectors can be safely interpreted as saucer‐shaped igneous sills, up to some hundreds of metres thick, some km wide. The occurrence of hydrothermal vent complexes and forced folds in the stratigraphic sequence above the sills constrain the intrusion age to the Miocene. Field observations and in‐situ magnetic susceptibility measurements of Oligocene–Miocene and Quaternary igneous rocks emplaced in coastal Senegal support this interpretation.  相似文献   

Imposex levels and concentrations of organotin compounds (TBT and its metabolites) in Nassarius nitidus from the Lagoon of Venice   总被引：1，自引：0，他引：1  

Pavoni B  Centanni E  Valcanover S  Fasolato M  Ceccato S  Tagliapietra D 《Marine pollution bulletin》2007,55(10-12):505-511

Specimens of Nassarius nitidus were collected in seven stations of the Venice Lagoon to assess the levels of tributyltin (TBT) and its metabolites monobutyltin and dibutyltin in the tissues and monitor their effect on organisms, in particular the phenomenon of imposex (superimposition of male sexual characteristics on females). The following values of population indices were found: vas deferens sequence: 1.2+/-0.7-4.0+/-0.5; relative penis length: 6-47%. The least impacted station was situated in the northern part of the Lagoon, where females without imposex were found and Butyltin (BuTs) concentrations in the organisms (average sum of BuTs=43+/-14 ngSng(-1)w.) were significantly lower than in the other stations (range of average sum of BuTs: 101+/-22-217+/-27 ngSng(-1)d.w.). Population indices were found to be related to the TBT content in the tissues. In particular VDSI had a significant logarithmic correlation: r=0.95, n=8, p<0.05.  相似文献   

Short-term response of the slow growing seagrass Posidonia oceanica to simulated anchor impact     

Ceccherelli G  Campo D  Milazzo M 《Marine environmental research》2007,63(4):341-349

Experimental evaluations about the impact of anchors of small vessels have previously shown that each anchoring can on average damage up to six shoots of Posidonia oceanica, removing small amount of biomass and, at the same time, interrupting continuity among shoots. The aim of the paper was to investigate the response of P. oceanica to different damage intensity at two levels of substrata compactness. Three treatments were considered: control (no damage); low damage (simulated anchor damage by three strokes of a hoe); and high damage (six strokes). Disturbance was higher where the substratum was highly penetrable and after one year significant variation was observed among treatments for both the number of leaves per shoot and shoot density. Conversely, the number of leaves per shoot by the end of the study was similar among all treatment combinations, suggesting that this was the only phenological feature that recovered, and probably the only result that through clonal integration could be achieved. These data strongly highlighted the role that anchoring might have on the slow growing seagrass P. oceanica meadow.  相似文献   

The MgCr2O4–MgFe2O4 solid solution series: effects of octahedrally coordinated Fe3+ on T–O bond lengths     

Davide Lenaz  Henrik Skogby  Francesco Princivalle  Ulf Hålenius 《Physics and Chemistry of Minerals》2006,33(7):465-474

The influence on the spinel structure of Fe³⁺ → Cr substitution was studied in flux-grown synthetic single crystals of the magnesiochromite–magnesioferrite (MgCr₂O₄–MgFe₂O₄) solid solution series. Samples were analysed by single-crystal X-ray diffraction, electron microprobe analyses, optical absorption and Mössbauer spectroscopy. With the exception of iron-poor samples (3–12 mol-% MgFe₂O₄), optical absorption and Mössbauer spectra show that iron occurs almost exclusively as trivalent Fe in the present samples. A very intense and broad absorption band at ca 7,800 cm^?1 dominates the optical absorption spectra of samples with higher Fe-contents. The appearance of this band is related to a distinct structural disorder of Fe³⁺ and a development of magnetic ordering as demonstrated by Mössbauer spectra. Profound composition-related changes are observed in the Mössbauer spectra, which are magnetically unsplit in the range 2–41 mol-% magnesioferrite, but become magnetically split in the range 59–100 mol-% magnesioferrite. Structural parameters a ₀ and M–O increase with magnesioferrite content and inversion degree, while u and T–O decrease. Our study confirms the previously reported (Lavina et al. 2002) influence of Fe³⁺ at the M site on T–O bond lengths in the spinel structure.  相似文献   

An Integrated Numerical Modelling–Discrete Fracture Network Approach Applied to the Characterisation of Rock Mass Strength of Naturally Fractured Pillars     

Davide Elmo  Doug Stead 《Rock Mechanics and Rock Engineering》2010,43(1):3-19

Naturally fractured mine pillars provide an excellent example of the importance of accurately determining rock mass strength. Failure in slender pillars is predominantly controlled by naturally occurring discontinuities, their influence diminishing with increasing pillar width, with wider pillars failing through a combination of brittle and shearing processes. To accurately simulate this behaviour by numerical modelling, the current analysis incorporates a more realistic representation of the mechanical behaviour of discrete fracture systems. This involves realistic simulation and representation of fracture networks, either as individual entities or as a collective system of fracture sets, or a combination of both. By using an integrated finite element/discrete element–discrete fracture network approach it is possible to study the failure of rock masses in tension and compression, along both existing pre-existing fractures and through intact rock bridges, and incorporating complex kinematic mechanisms. The proposed modelling approach fully captures the anisotropic and inhomogeneous effects of natural jointing and is considered to be more realistic than methods relying solely on continuum or discontinuum representation. The paper concludes with a discussion on the development of synthetic rock mass properties, with the intention of providing a more robust link between rock mass strength and rock mass classification systems.  相似文献   

Innovative methods of correlation and orbit determination for space debris     

Davide Farnocchia  Giacomo Tommei  Andrea Milani  Alessandro Rossi 《Celestial Mechanics and Dynamical Astronomy》2010,107(1-2):169-185

We propose two algorithms to provide a full preliminary orbit of an Earth-orbiting object with a number of observations lower than the classical methods, such as those by Laplace and Gauss. The first one is the Virtual debris algorithm, based upon the admissible region, that is the set of the unknown quantities corresponding to possible orbits for a given observation for objects in Earth orbit (as opposed to both interplanetary orbits and ballistic ones). A similar method has already been successfully used in recent years for the asteroidal case. The second algorithm uses the integrals of the geocentric 2-body motion, which must have the same values at the times of the different observations for a common orbit to exist. We also discuss how to account for the perturbations of the 2-body motion, e.g., the J ₂ effect.  相似文献   

Introduction: Integrating geosciences for fractured reservoir characterization     

Davide Calcagni  Laurence Nicoletis  Juan Soldo 《Geophysical Prospecting》2009,57(2):165-165

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Hydrothermal dolomitization in platform and basin carbonate successions during thrusting: A hydrocarbon reservoir analogue (Mesozoic of Venetian Southern Alps,Italy)     

Paola Ronchi  Daniele Masetti  Stefano Tassan  Davide Camocino 《Marine and Petroleum Geology》2012,29(1):68-89

The Early Jurassic dolomitized carbonates in the Venetian Alp, represent a surface analogue of the hydrocarbon exploration targets in Adriatic offshore and Po Plain, Italy. Dolomitization affected the carbonate platform of Monte Zugna Formation (Lower Jurassic) and the Neptunian dikes breccia in the pelagic Maiolica Formation (Uppermost Jurassic–Lower Cretaceous) improving the poro-perm characteristics. Petrography, stable isotope, strontium isotope ratio, trace element and fluid inclusion analyses were carried out on samples from the Monte Grappa Anticline, which is the direct analogue for subsurface. The petrographic analyses showed a first pervasive, replacement dolomitization phase (D1) followed by volumetrically less important dolomite cement precipitation phases (D2, D3, DS). The same, quite wide range of oxygen isotope (?9 to ?2‰ V-PDB) is observed in all dolomite types. The δ¹³C range is in the positive field of marine derived carbonate (from +0.5 to +3.2‰ PDB). The trace element analysis showed a slight enrichment in Fe and Mn contents in the Monte Zugna dolostones with respect the original limestone. The same dolomite precipitation temperature (up to 105 °C Th) was observed in the replacement and cement dolomites, suggesting a unique dolomitization event. This temperature, largely higher than the maximum burial temperature (about 50 °C), supports a hydrothermal origin of the dolomitizing fluids, which had a seawater to brackish composition. The data collected suggest a hydrothermal dolomitization occurring during to the South Alpine thrusting according to the “squeegee model”. The interpretation is consistent with the dolomitization model proposed for similar Jurassic successions in the Central Southern Alps. This study indicates that the deformed foreland and thrust fold belts carbonates in Po Plain and Adriatic offshore are suitable to be dolomitized, and therefore reflect an efficient hydrocarbon exploration play.  相似文献