Petrophysical study of faults in sandstone using petrographic image analysis and X-ray computerized tomography     

M. Antonellini  A. Aydin  D. D. Pollard  P. D'Onfro 《Pure and Applied Geophysics》1994,143(1-3):181-201

Petrographic image analysis (PIA) and X-ray computerized tomography (CT) provide local determinations of porosity in sandstone. We have investigated small faults called deformation bands in porous sandstones using these techniques. Because the petrophysical properties of the fault rock vary at a small scale (mm scale), the ability of PIA and CT to determine porosity in small volumes of rock and to map porosity distribution in two and three dimensions is crucial. This information is used to recognize the processes involved in fault development and the different kinds of microstructures associated with dilatancy and compaction. The petrophysical study of fault rock in sandstone permits one to make predictions of the hydraulic properties of a fault and thereby evaluate the sealing or fluid transmitting characteristics of faulted reservoirs and aquifers. The results of this study indicate that faulting in sandstone alters the original porosity and permeability of the host rock: the porosity is reduced by an order of magnitude and the permeability is reduced by one to more than seven orders of magnitude for faults associated with compaction.  相似文献   

Use of joint-growth directions and rock textures to infer thermal regimes during solidification of basaltic lava flows     

James M. Degraff  Philip E. Long  Atilla Aydin 《Journal of Volcanology and Geothermal Research》1989,38(3-4)

Thermal contraction joints form in the upper and lower solidifying crusts of basaltic lava flows and grow toward the interior as the crusts thicken. Lava flows are thus divided by vertical joints that, by changes in joint spacing and form, define horizontal intraflow layers known as tiers. Entablatures are tiers with joint spacings less than about 40 cm, whereas colonnades have larger joint spacings. We use structural and petrographic methods to infer heat-transfer processes and to constrain environmental conditions that produce these contrasting tiers. Joint-surface morphology indicates overall joint-growth direction and thus identifies the level in a flow where the upper and lower crusts met. Rock texture provides information on relative cooling rates in the tiers of a flow. Lava flows without entablature have textures that develop by relatively slow cooling, and two joint sets that usually meet near their middles, which indicate mostly conductive cooling. Entablature-bearing flows have two main joint sets that meet well below their middles, and textures that indicate fast cooling of entablatures and slow cooling of colonnades. Entablatures always occur in the upper joint sets and sometimes alternate several times with colonnades. Solidification times of entablature-bearing flows, constrained by lower joint-set thicknesses, are much less than those predicted by a purely conductive cooling model. These results are best explained by a cooling model based on conductive heat transfer near a flow base and water-steam convection in the upper part of an entablature-bearing flow. Calculated solidification rates in the upper parts of such flows exceed that of the upper crust of Kilauea Iki lava lake, where water-steam convection is documented. Use of the solidification rates in an available model of water-steam convection yields permeability values that agree with measured values for fractured crystalline rock. We conclude, therefore, that an entablature forms when part of a flow cools very rapidly by water-steam convection. Flooding of the flow top by surface drainage most likely induces the convection. Colonnades form under conditions of slower cooling by conductive heat transfer in the absence of water.  相似文献   

Petrogenesis of the Neogene alkaline volcanics with implications for post-collisional lithospheric thinning of the Eastern Pontides, NE Turkey   总被引：2，自引：0，他引：2  

Faruk Aydin  Orhan Karsli  Bin Chen 《Lithos》2008,104(1-4):249-266

Whole-rock geochemistry, Sr–Nd–Pb isotopes and K–Ar data are reported for alkaline samples collected from the Neogene alkaline volcanics (NAVs) in the Eastern Pontides, northeastern Turkey, in order to investigate their source and petrogenesis and geodynamic evaluation of the region. The NAVs were made of three groups that comprise of basanite–tephrite (feldspar-free; Group A), tephrite–tephriphonolite (feldspar and feldspathoid-bearing; Group B) and alkaline basalt–rhyolite (feldspathoid-free; Group C) series. These rocks cover a broad compositional range from silica-undersaturated to silica-oversaturated types, almost all of which are potassic in character. They show enrichment of LREE and LILE and depletion of HFSE, without a Eu anomaly in most of the mafic samples. Textural features and calculated pressures based on the Cpx-barometer in each series indicate that the alkaline magma equilibrated at shallow crustal depths under a pressure of about 3–4.5 kbar and approximating a crystallization depth of 9–14 km. The NAVs are slightly depleted in isotopic composition, with respect to ⁸⁷Sr/⁸⁶Sr (ranging from 0.705018 to 0.705643) and ¹⁴³Nd/¹⁴⁴Nd (ranging from 0.512662 to 0.512714) that indicate young Nd model ages (0.51–059 Ga). This may indicate that the parent melts tapped a homogeneous and young lithospheric mantle source which was metasomatized by subduction-derived sediments during the Late Mesozoic. Pb isotopic compositions (²⁰⁶Pb/²⁰⁴Pb = 18.85–18.95; ²⁰⁷Pb/²⁰⁴Pb = 15.60–15.74; ²⁰⁸Pb/²⁰⁴Pb = 38.82–39.25) may also be consistent with a model for an enriched subcontinental lithospheric mantle source. Lithospheric thinning and resultant upwelling of asthenosphere induced by lithospheric delamination may have favoured partial melting of chemically enriched, young lithospheric mantle beneath the Eastern Pontides. Then, the melt subsequently underwent a fractional crystallization process along with or without minor amounts of crustal assimilation, generating a wide variety of rock types in a post-collision extensional regime in the Eastern Pontides during the Neogene.  相似文献   

Seismic hazard analysis of Laoag City,Northern Philippines for liquefaction potential assessment     

M.A.A. Beroya  A. Aydin 《Engineering Geology》2008,96(1-2):28-42

A seismic hazard analysis was conducted in Laoag City, Northern Philippines to determine the design ground motion for liquefaction potential assessment of the area. Because the hazard analysis was done within the framework of liquefaction potential assessment, only those earthquakes with magnitude–distance combinations that are capable of generating liquefaction were considered in the study. Both probabilistic and deterministic approaches were used in the analysis. From the results of the probabilistic analysis, seismic hazard curves were generated from which the ground motion with a 10% probability of exceedance in 50years was obtained. This was then modified in consideration of the soft soil condition in the study area. Deaggregation was performed to determine the most likely earthquake to generate the said level of ground shaking.  相似文献   

Predicting Performance of Raise Boring Machines Using Empirical Models     

Aydin Shaterpour-Mamaghani  Nuh Bilgin  Cemal Balci  Emre Avunduk  Can Polat 《Rock Mechanics and Rock Engineering》2016,49(8):3377-3385

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Mineralogy and Chemistry of Biotites from Eastern Pontide Granitoid Rocks, NE-Turkey: Some Petrological Implications for Granitoid Magmas   总被引：2，自引：0，他引：2  

F. Aydin  O. Karsli  M.B. Sadiklar 《Chemie der Erde / Geochemistry》2003,63(2):163-182

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Spectroscopic study of the supergiant star 6 Cassiopeiae     

Cemal Aydin 《Astrophysics and Space Science》1979,64(2):481-507

Twenty-five coudé spectrograms (22 with dispersion 12 Å mm^–1 and three 7 Å mm^–1) of 6 Cassiopeiae (A3 Ia) have been studied. The observations were made at the Haute Provence Observatory. The results of the analysis suggest a correlation between the variations of the equivalent widths, the microturbulence and the radial velocity. The radial velocity and turbulent velocity present a rapid variation with time, even in intervals as short as about an hour. The hydrogen lines are slightly asymmetric but the strongest Feii lines are clearly asymmetric. We found that the amount of asymmetry of the strongest Feii lines (I>6) correlates with the loggf value, with the estimated laboratory intensityI, and with the equivalent widthW .The observations have been made at the Astronomical Observatory of Haute Provence (CNRS). This work has been supported by TUBITAK (Scientific and Technical Research Council of Turkey), and partially by CNR (Consiglio Nazionale delle Ricerche) of Italy.  相似文献   

Permeability of a fault zone crosscutting a sequence of sandstones and shales and its influence on hydraulic head distribution in the Chatsworth Formation,California, USA   总被引：2，自引：1，他引：1  

Antonino Cilona  Atilla Aydin  Nicholas M. Johnson 《Hydrogeology Journal》2015,23(2):405-419

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Chemical Speciation of Vanadium in Coal Bottom Ash     

Firat Aydin  Abdurrahman Saydut  Beniz Gunduz  Isil Aydin  Candan Hamamci 《洁净——土壤、空气、水》2012,40(4):444-448

Chemical speciation of vanadium is important to understand the true nature of this element in the environment as well as its biochemical pathways. Sample pretreatment, preparation, and chemical speciation methods were applied for vanadium in coal bottom ash here. Two‐stage microwave acid digestion was used to preparation of samples. Determination of vanadium was performed using inductively coupled plasma‐optical emission spectrometry (ICP‐OES). Speciation of vanadium was carried out using a seven‐step sequential extraction procedure of the coal bottom ash each releasing species of vanadium: Water soluble, exchangeable, carbonate, reducible, oxidizable, sulfide, and residual fractions. Total vanadium concentration in the coal bottom ash is 701 mg kg^?1 d.w. The most abundant form of vanadium in coal bottom ash is residual fraction of vanadium (196 mg kg^?1 d.w.). Relative abundances of the remaining vanadium fractions in coal bottom ash are as follows: Reducible (176 mg kg^?1 d.w.) > sulfide (176 mg kg^?1 d.w.) > carbonate (85 mg kg^?1 d.w.) > oxidizable (50 mg kg^?1 d.w.) > water soluble (10.6 mg kg^?1 d.w.) > exchangeable (9.0 mg kg^?1 d.w.).  相似文献   

A precise gravimetric geoid model in a mountainous area with scarce gravity data: a case study in central Turkey   总被引：1，自引：0，他引：1  

Ramazan A. Abbak  Lars E. Sj?berg  Artu Ellmann  Aydin Ustun 《Studia Geophysica et Geodaetica》2012,56(4):909-927

In mountainous regions with scarce gravity data, gravimetric geoid determination is a difficult task that needs special attention to obtain reliable results satisfying the demands, e.g., of engineering applications. The present study investigates a procedure for combining a suitable global geopotential model and available terrestrial data in order to obtain a precise regional geoid model for Konya Closed Basin (KCB). The KCB is located in the central part of Turkey, where a very limited amount of terrestrial gravity data is available. Various data sources, such as the Turkish digital elevation model with 3 ?? × 3?? resolution, a recently published satellite-only global geopotential model from the Gravity Recovery and Climate Experiment satellite (GRACE) and the ground gravity observations, are combined in the least-squares sense by the modified Stokes?? formula. The new gravimetric geoid model is compared with Global Positioning System (GPS)/levelling at the control points, resulting in the Root Mean Square Error (RMS) differences of ±6.4 cm and 1.7 ppm in the absolute and relative senses, respectively. This regional geoid model appears to be more accurate than the Earth Gravitational Model 2008, which is the best global model over the target area, with the RMS differences of ±8.6 cm and 1.8 ppm in the absolute and relative senses, respectively. These results show that the accuracy of a regional gravimetric model can be augmented by the combination of a global geopotential model and local terrestrial data in mountainous areas even though the quality and resolution of the primary terrestrial data are not satisfactory to the geoid modelling procedure.  相似文献