Monoclinal flexure of an orogenic plateau margin during subduction,south Turkey     

David Fernndez‐Blanco  Giovanni Bertotti  Ali Aksu  Jeremy Hall 《Basin Research》2019,31(4):709-727

Geologic evidence across orogenic plateau margins enables the discrimination of the relative contributions of orogenic, epeirogenic and/or climatic processes that lead to growth and maintenance of those plateaus and their margins. Here, we discuss the mode of formation of the southern margin of the Central Anatolian Plateau (SCAP) and evaluate its time of formation using fieldwork in the onshore and seismic reflection data in the offshore. In the onshore, uplifted Miocene rocks in a dip‐slope topography show monocline flexure over >100 km, km‐scale asymmetric folds verging south, and outcrop‐scale syn‐sedimentary reverse faults. On the Turkish shelf, vertical faults transect the basal latest Messinian of a 10 km fold where on‐structure syntectonic wedges and synsedimentary unconformities indicate pre‐Pliocene uplift and erosion, followed by Pliocene and younger deformation. Collectively, Miocene rocks delineate a flexural monocline at plateau margin scale that is expressed along our on‐offshore sections as a kink‐band fold with a steep flank 20–25 km long. In these reconstructed sections, we estimate a relative vertical displacement of 3.8 km at rates of ca. 0.5 mm/y, and horizontal shortening values <1 %. We use this evidence together with our observations of shortening at outcrop, basin, plateau‐margin and forearc‐system scales to infer that the SCAP forms as a monoclinal flexure to accommodate deep‐seated thickening and shortening since >5 Ma, and to contextualize the plateau margin as the forearc high of the Cyprus subduction system.  相似文献   

Aliphatic hydrocarbons in the bitumens of the Puertollano oil shales     

A. G. Borrego  P. Bernard  C. G. Blanco 《Applied Geochemistry》1999,14(8):1237

The aliphatic fraction of the bitumens from 3 bands of the Puertollano oil shale field have been studied by gas chromatography and gas chromatography/mass spectrometry. Previous work published over the last years reached different conclusions about the origin of the organic matter in the Puertollano oil shales. A reappraisal of some of the biomarkers was then needed for a better understanding of the aliphatic hydrocarbons assemblage. The identified compounds, mainly n-alkanes in the medium to high boiling point region, acyclic isoprenoids and hopane-related compounds point towards a predominant algal/bacterial input. No unequivocally higher plant derived biomarkers have been detected in significant amounts, suggesting that the bulk of the organic matter derive from authocthonous organisms living in the basin. The biomarker maturity ratios indicate that the 3 Puertollano oil shales have similar maturities and are close to the onset of oil generation, assessing a slightly higher maturity than that determined by petrographic techniques.  相似文献   

Radio source calibration for the Very Small Array and other cosmic microwave background instruments at around 30 GHz     

Yaser A. Hafez  Rod D. Davies  Richard J. Davis  Clive Dickinson  Elia S. Battistelli  Francisco Blanco  Kieran Cleary  Thomas Franzen  Ricardo Genova-Santos  Keith Grainge  Michael P. Hobson  Michael E. Jones  Katy Lancaster  Anthony N. Lasenby  Carmen P. Padilla-Torres  José Alberto Rubiño-Martin  Rafael Rebolo  Richard D. E. Saunders  Paul F. Scott  Angela C. Taylor  David Titterington  Marco Tucci  Robert A. Watson 《Monthly notices of the Royal Astronomical Society》2008,388(4):1775-1786

Accurate calibration of data is essential for the current generation of cosmic microwave background (CMB) experiments. Using data from the Very Small Array (VSA), we describe procedures which will lead to an accuracy of 1 per cent or better for experiments such as the VSA and CBI. Particular attention is paid to the stability of the receiver systems, the quality of the site and frequent observations of reference sources. At 30 GHz the careful correction for atmospheric emission and absorption is shown to be essential for achieving 1 per cent precision.
The sources for which a 1 per cent relative flux density calibration was achieved included Cas A, Cyg A, Tau A and NGC 7027 and the planets Venus, Jupiter and Saturn. A flux density, or brightness temperature in the case of the planets, was derived at 33 GHz relative to Jupiter which was adopted as the fundamental calibrator. A spectral index at ∼30 GHz is given for each.
Cas A, Tau A, NGC 7027 and Venus were examined for variability. Cas A was found to be decreasing at 0.394 ± 0.019 per cent yr⁻¹ over the period 2001 March to 2004 August. In the same period Tau A was decreasing at 0.22 ± 0.07 per cent yr⁻¹. A survey of the published data showed that the planetary nebula NGC 7027 decreased at 0.16 ± 0.04 per cent yr⁻¹ over the period 1967–2003. Venus showed an insignificant (1.5 ± 1.3 per cent) variation with Venusian illumination. The integrated polarization of Tau A at 33 GHz was found to be 7.8 ± 0.6 per cent at position angle =148°± 3°.  相似文献   

Interaction between magnetic clouds and the heliospheric current sheet at 1 AU as it is observed by one single observation point     

J.J. Blanco  M.A. Hidalgo  J. Rodriguez-Pacheco  J. Medina 《Journal of Atmospheric and Solar》2011,73(11-12):1339-1347

The effect of Magnetic Clouds (MCs) on the Heliospheric Current Sheet (HCS) local structure is yet an open question. Although it is widely accepted that a magnetic cloud has an important effect on the HCS shape, their structural relation, either the MC is part of the HCS or not, is not completely solved. Moreover, the problem grows up when trying to investigate three dimensional structures using one single observation point. We propose an approach to the MC–HCS study using magnetic models for the MC and local HCS structures, which are able of determining their relative orientation from one single spacecraft data. Three events have been selected in which an MC passage was observed close to HCS crossings. The results confirm the strong effect of MC passage on the HCS local orientation and they seem to be consistent with MCs propagating out of the HCS at 1 AU.  相似文献   

Radar interferometry techniques for the study of ground subsidence phenomena: a review of practical issues through cases in Spain   总被引：5，自引：0，他引：5  

R. Tomás  R. Romero  J. Mulas  J. J. Marturià  J. J. Mallorquí  J. M. Lopez-Sanchez  G. Herrera  F. Gutiérrez  P. J. González  J. Fernández  S. Duque  A. Concha-Dimas  G. Cocksley  C. Castañeda  D. Carrasco  P. Blanco 《Environmental Earth Sciences》2014,71(1):163-181

Subsidence related to multiple natural and human-induced processes affects an increasing number of areas worldwide. Although this phenomenon may involve surface deformation with 3D displacement components, negative vertical movement, either progressive or episodic, tends to dominate. Over the last decades, differential SAR interferometry (DInSAR) has become a very useful remote sensing tool for accurately measuring the spatial and temporal evolution of surface displacements over broad areas. This work discusses the main advantages and limitations of addressing active subsidence phenomena by means of DInSAR techniques from an end-user point of view. Special attention is paid to the spatial and temporal resolution, the precision of the measurements, and the usefulness of the data. The presented analysis is focused on DInSAR results exploitation of various ground subsidence phenomena (groundwater withdrawal, soil compaction, mining subsidence, evaporite dissolution subsidence, and volcanic deformation) with different displacement patterns in a selection of subsidence areas in Spain. Finally, a cost comparative study is performed for the different techniques applied.  相似文献   

A modified rock physics model for analysis of seismic signatures of low gas-saturated rocks     

Perveiz Khalid  Daniel Broseta  Dan Vladimir Nichita  Jacques Blanco 《Arabian Journal of Geosciences》2014,7(8):3281-3295

In seismic applications, the bulk modulus of porous media saturated with liquid and gas phases is often estimated using Gassmann's fluid substitution formula, in which the effective bulk modulus of the two-phase fluid is the Reuss average of the gas and liquid bulk moduli. This averaging procedure, referred to as Wood's approximation, holds if the liquid and gas phases are homogeneously distributed within the pore space down to sizes well below the seismic wavelength and if the phase transfer processes between liquid and gas domains induced by the pressure variations of the seismic wave are negligible over the timescale of the wave period. Using existing theoretical results and low-frequency acoustic measurements in bubbly liquids, we argue that the latter assumption of “frozen” phases, valid for large enough frequencies, is likely to fail in the seismic frequency range where lower effective bulk modulus and velocity, together with dispersion and attenuation effects, are expected. We provide a simple method, which extends to reservoir fluids a classical result by Landau and Lifshitz valid for pure fluids, to compute the effective bulk modulus of thermodynamically equilibrated liquid and gas phases. For low gas saturation, this modulus is significantly lower than its Wood's counterpart, especially at the crossing of bubble point conditions. A seismic reflector associated to a phase transition between a monophasic and a two-phase fluid thus will appear. We discuss the consequences of these results for various seismic applications including fizz water discrimination and hydrocarbon reservoir depletion and CO₂ geological storage monitoring.  相似文献   

Variability of Circumstellar Emission from Dust Envelopes Around Carbon Stars     

A. Blanco  A. Borghesi  E. Epifani  S. Fonti  V. Orofino  F. Strafella 《Astrophysics and Space Science》1997,251(1-2):97-102

The main constituents of the dust, produced around late-type carbon stars, are thought to be carbon and silicon carbide (SiC), although their exact nature is not yet well established. This subject has been addressed by several authors and good fits of a large number of IRAS sources (chosen among the carbon stars exhibiting the SiC feature at about 11.3 μm) were obtained. In this work we use the same procedure on a limited number of objects, of the same type, taking into account the variability of such sources and the changes induced in their IR spectra. For this purpose, the chosen stars have been observed with a spectral resolution higher than that available for the IRAS data (λ/Δλ ≅ 50), using the CGS3 instrument of the UKIRT telescope, both in the low (λ/Δλ ≅ 160) and in the high (λ/Δλ ≅ 500) resolution configuration. The results are discussed and some preliminary conclusions are drawn. This revised version was published online in September 2006 with corrections to the Cover Date.  相似文献   

Infrared transmission spectroscopy of carbonate samples of biotic origin relevant to Mars exobiological studies     

Vincenzo Orofino  Armando Blanco  Marcella D'Elia  Domenico Licchelli  Sergio Fonti 《Icarus》2007,187(2):457-463

Because it is possible that Mars experienced an ancient climate warmer and wetter than the present one, it is reasonable to suppose that simple forms of life developed there, in the underground or at the surface, as in the terrestrial primitive biosphere. In this work we have performed infrared (IR) transmission spectroscopic analyses directed to examine the reaction to heat treatments of biotic (fresh and fossil materials) and abiotic particulate samples composed of calcium carbonate (aragonite or calcite). The aim is to check if IR spectroscopy can be a useful tool for discriminating between abiotic and biotic (fossil) carbonate samples collected on the martian surface, during in situ or sample-return missions. An important result we found is that, after thermal processing, it is possible to distinguish, by means of IR spectroscopy, abiotic aragonite from aragonite of recent biological origin. In addition we have found that the spectral behaviour of all the analysed fossil samples after heat treatment is the same as that of fresh biotic material irrespective of the original structure (whether aragonite or calcite).  相似文献   

Comment on: “Chemostratigraphic constraints on early Ediacaran carbonate ramp dynamics,Río de la Plata craton,Uruguay” by Aubet et al. Gondwana Research,Volume 22, Issues 3-4, November 2012, Pages 1073-1090     

Claudio Gaucher  Alcides N. Sial  Robert Frei  Peter Sprechmann  Jorge Bossi  Daniel G. Poiré  Gonzalo Blanco  Leda Sánchez Bettucci 《Gondwana Research》2013,23(3):1183-1185

  相似文献   

Contribution to hydrological modelling of small Amazonian catchments: application of rainfall–runoff models to simulate flow duration curves     

C.J.C. Blanco  S.S.M. Santos  M.C. Quintas  M.V.A. Vinagre  A.L.A. Mesquita 《水文科学杂志》2013,58(7):1423-1433

Abstract

The objective of this study is to analyse three rainfall–runoff hydrological models applied in two small catchments in the Amazon region to simulate flow duration curves (FDCs). The simple linear model (SLM) considers the rainfall–runoff process as an input–output time-invariant system. However, the rainfall–runoff process is nonlinear; thus, a modification is applied to the SLM based on the residual relationship between the simulated and observed discharges, generating the modified linear model (MLM). In the third model (SVM), the nonlinearity due to infiltration and evapotranspiration is incorporated into the system through the sigmoid variable gain factor. The performance criteria adopted were a distance metric (δ) and the Nash-Sutcliffe coefficient (R²) determined between simulated and observed flows. The good results of the models, mainly the MLM and SVM, showed that they could be applied to simulate FDCs in small catchments in the Amazon region.

Editor D. Koutsoyiannis; Associate editor A. Montanari

Citation Blanco, C.J.C., Santos, S.S.M., Quintas, M.C., Vinagre, M.V.A., and Mesquita, A.L.A., 2013. Contribution to hydrological modelling of small Amazonian catchments: application of rainfall–runoff models to simulate flow duration curves. Hydrological Sciences Journal, 58 (7), 1–11.  相似文献