Two‐dimensional joint inversions of cross‐hole resistivity data and resolution analysis of combined arrays

In this study, a new two‐dimensional inversion algorithm was developed for the inversion of cross‐hole direct current resistivity measurements. In the last decades, various array optimisation methods were suggested for resistivity tomography. However, researchers have still collected data by using classical electrode arrays in most cross‐hole applications. Therefore, we investigated the accuracy of both the individual and the joint inversion of the classical cross‐hole arrays by using both synthetic and field data with the developed algorithm. We showed that the joint inversion of bipole–bipole, pole–bipole, bipole–pole, and pole–tripole electrode arrays gives inverse solutions that are closer to the real model than the individual inversions of the electrode array datasets for the synthetic data inversion. The model resolution matrix of the suggested arrays was used to analyse the inversion results. This model resolution analysis also showed the advantage of the joint inversion of bipole–bipole, pole–bipole, bipole–pole, and pole–tripole arrays. We also used sensitivity sections from each of the arrays and their superpositions to explain why joint inversion gives better resolution than the any individual inversion result.     

Comparison of Planimetric and Thematic Accuracy of OrbView-3 and IKONOS Images

Spatial mapping from space using high-resolution satellite sensor data instead of conventional data collection techniques widely gained popularity. This study aims to analyze the planimetric and thematic accuracy of high-resolution OrbView-3 and IKONOS orthoimages. OrbView-3 and IKONOS images of a test area were acquired and these images were geometrically corrected using rational polynomial functions to conduct accuracy assessment. 40 Ground Control Points (GCPs) generated from static Global Positioning System (GPS) survey were used in the orthorectification procedure. 182 Test Points (TPs) produced from terrestrial surveying technique were used to analyze the accuracy of orthorectifications. Root Mean Square Error (RMSE) values obtained for GCPs and TPs were used to determine the planimetric accuracy of these images. Thematic accuracy analyses were conducted in radiometric and spatial base. Transects, lines and polygons were created to analyze the radiometric quality of data sets and to determine minimum distinguishable distance and distinguishable area. Both planimetric and thematic accuracy analyses illustrated that OrbView-3 and IKONOS images could be used to create 1:10000 scale map of the concerned region with appropriate planimetric and thematic quality.     

Sediment concentrations of heavy metals in the Homa Lagoon (Eastern Aegean Sea): Assessment of contamination and ecological risks

The concentrations of heavy metals and organic carbon in sediment of the Homa Lagoon which is one of the most productive lagoons and commercial important active fish trap in the Eastern Aegean Sea, were investigated in order to describe the temporal and spatial distributions of metals. These results were used to evaluate possible ecological risks that could be a problem for the environment of the lagoon in the future. Sediments were enriched with Cr, Ni and considered as heavily polluted per the SQG. The C_f of Ni and Cr were presented moderate level of contamination in this area. The C_d levels indicated moderate degree of contamination at station B, C, D and E due to agricultural drainage water, industrial and domestic wastewater, are transported by the Gediz River. Sediments from Homa Lagoon were most toxic for Ni due to exceedances of the TEL and PEL values.     

Discovery of the Late Triassic (Middle Carnian–Rhaetian) radiolarians in the volcano-sedimentary sequences of the Kocali Complex,SE Turkey: Correlation with the other Tauride units

The Kocali Complex in SE Turkey includes pelagic sediments (pelagic limestones, cherts, etc.), basic volcanic rocks of oceanic crust origin together with platform-derived sediments. Its depositional age was previously assigned as Late Jurassic–Early Cretaceous. In order to study the radiolarian contents of volcano-sedimentary sequences in this complex, six stratigraphic sections have been measured mainly at the NE and NW Adiyaman city.Radiolarian faunas from these stratigraphic sections reveal that the age of these sequences ranges from middle Carnian to Rhaetian. Based on these data, the depositional age of the complex is older than the previously assigned. Lithological characteristics (widespread Triassic basic volcanic rocks associated with pelagic sediments) and radiolarian contents of these sequences have close similarities with the sequences of the Alakircay Nappe of the Antalya Nappes in western and central Taurides.Based on taxonomic studies, 99 taxa have been determined of which one genus (Adiyamanium) and four species (Monocapnuchosphaera kocaliensis, Paronaella speciosa, Ferresium okuyucui and Adiyamanium crassum) are described as new.     

Transferring the international DRR policy into the local context

The disaster experiences of the past resulted in the need for a new international policy. The paper examines the transfer of the international policy for disaster risk reduction (DRR) into a local context, Turkey and Turkish, where new and old perspectives meet. Analyzed is a corpus consisting of two texts, with the purpose of examining the concepts’ actual use and contexts shaped by different attitudes, based on the three-dimensional framework of critical discourse analysis, translation studies and conceptual history. The concept transfer from international to the local level inevitably involves translation. The texts included “new” DRR terms as a result of the concealed translation attempts to adjust the old and contemporary terminologies. Thus, non-functional terms with blurred meanings arose. The awareness that such processes of transfer are complex would help to overcome this kind of simplistic top-down approaches and to give priority to “communicative labor.” The framework is not presented due to space limitations. It was also observed that the Turkish terminology lacks clear definitions. To affirm this, an in-depth analysis is needed. Terms transferred across contexts may end lacking conceptualizations due to non-functional translation choices. When adopting new social policies, this can be overcome through making effort for communication. This research looks at conceptual struggles related to social issues from a different aspect. The vague terms and inefficiencies in social implementations can be avoided by authorities being aware that discourse, translation and their production are parts of social action.     

Upper crustal electrical resistivity structures in the vicinity of the Çatalca Fault, Istanbul, Turkey by magnetotelluric data

A magnetotelluric survey was performed at the Çatalca Region, west of Istanbul, Turkey with the aim of investigating geoelectrical properties of the upper crust near the Çatalca Fault and its vicinity. Broadband magnetotelluric data were collected at nine sites along a single southwest-northeast profile to image the electrical resistivity structure from surface to the 5 km depth. The dimensionality of the data was examined through tensor decompositions and highly two-dimensional behavior of the data is shown. Following the tensor decompositions, two-dimensional inversions were carried out where E-polarization, B-polarization and tipper data were utilized to construct electrical resistivity models. The results of the inversions suggest: a) the Çatalca Fault extends from surface to 5 km depth as a conductive zone dipping to southwest; b) the thickness of the sedimentary cover is increasing from SW to NE to 700 m with low resistivity values between 1–100 Ωm; c) the crystalline basement below the sedimentary unit is very resistive and varies between 2000–100000 Ωm; d) a SW-dipping resistivity boundary in the northeastern part of our profile may represent the West Black Sea Fault.     

Vineyard site suitability analysis by use of multicriteria approach applied on geo-spatial data

Abstract

In this research, multicriteria decision analysis with pairwise comparison weighting method was utilized to determine the suitable locations for vineyard plantation in Sarkoy region of Turkey. Soil maps, meteorological measurements, slope, aspect and elevation maps were used as input to conduct spatial analysis. Different methods were compared and pairwise comparison method was identified as the most appropriate method of weighting for this spatial analysis. Current vineyard areas were determined using Worldview-2 imagery and their spatial distribution compared with the resulting suitability map to determine the current suitability. Comparisons showed current vineyards were mostly established in locations where suitability map expresses low capability. Further inspection unveiled that, these low capability lands are closer to the transportation networks and city/county centres that tend to be in sea level elevations as opposed to vine grapes thriving in higher altitudes. Results also enabled providing suggestions on alternative sites for new vineyard plantation.     

Seasonality of low flows and dominant processes in the Rhine River

Low flow forecasting is crucial for sustainable cooling water supply and planning of river navigation in the Rhine River. The first step in reliable low flow forecasting is to understand the characteristics of low flow. In this study, several methods are applied to understand the low flow characteristics of Rhine River basin. In 108 catchments of the Rhine River, winter and summer low flow regions are determined with the seasonality ratio (SR) index. To understand whether different numbers of processes are acting in generating different low flow regimes in seven major sub-basins (namely, East Alpine, West Alpine, Middle Rhine, Neckar, Main, Mosel and Lower Rhine) aggregated from the 108 catchments, the dominant variable concept is adopted from chaos theory. The number of dominant processes within the seven major sub-basins is determined with the correlation dimension analysis. Results of the correlation dimension analysis show that the minimum and maximum required number of variables to represent the low flow dynamics of the seven major sub-basins, except the Middle Rhine and Mosel, is 4 and 9, respectively. For the Mosel and Middle Rhine, the required minimum number of variables is 2 and 6, and the maximum number of variables is 5 and 13, respectively. These results show that the low flow processes of the major sub-basins of the Rhine could be considered as non-stochastic or chaotic processes. To confirm this conclusion, the rescaled range analysis is applied to verify persistency (i.e. non-randomness) in the processes. The estimated rescaled range statistics (i.e. Hurst exponents) are all above 0.5, indicating that persistent long-term memory characteristics exist in the runoff processes. Finally, the mean values of SR indices are compared with the nonlinear analyses results to find significant relationships. The results show that the minimum and maximum numbers of required variables (i.e. processes) to model the dynamic characteristics for five out of the seven major sub-basins are the same, but the observed low flow regimes are different (winter low flow regime and summer low flow regime). These results support the conclusion that a few interrelated nonlinear variables could yield completely different behaviour (i.e. dominant low flow regime).     

Source rock characteristics and biostratigraphy of the Lower Silurian (Telychian) organic-rich shales at Akyaka, central Taurus region, Turkey

The Akyaka section in the central Taurus region in the southern part of Turkey includes the organic matter and graptolite-rich black shales which were deposited under dysoxic to anoxic marine conditions in the Early Silurian. A biostratigraphical analysis, based on graptolite assemblages, indicates that the sediments studied may well be referable to the querichi Biozone and early Telychian, Llandovery. A total of 15 samples have been subjected to Leco and Rock-Eval pyrolysis and graptolite reflectance measurements for determination of their source rock characteristics and thermal maturity. The total organic carbon content of the graptolite-bearing shales varies from 1.75 to 3.52 wt% with an average value of 2.86 wt%. The present Rock-Eval pyrolytic yields and calculated values of hydrogen and oxygen indexes imply that the recent organic matter type is inert kerogen. The measured maximum graptolite reflectance (G_Rmax %) values are between 5.04% and 6.75% corresponding to thermally over maturity. This high maturity suggests a deep burial of the Lower Silurian sediments resulting from overburden rocks of Upper Paleozoic to Mesozoic Upper Cretaceous and Middle-Upper Eocene thrusts occurred in the region.     

Evaluation of burial history, thermal maturity and source-rock assessment of the Upper Paleozoic succession of the eastern Taurus region, southern Turkey

The regional burial history pattern, thermal maturity variations and source rock assessment of the sedimentary succession in the eastern Taurus region, in the southern part of Turkey, have been studied on surface samples collected from the six different sections which represent the entire region. Organic petrography (Thermal Alteration Index) and geochemical data (TOC content, T_max and HI values) were obtained from transmitted-light microscopy and Rock-Eval pyrolysis.The Lower Paleozoic (Cambrian, Ordovician and Silurian) strata were not investigated and modeled in terms of the maturity and hydrocarbon source rock potential, because of their poor organic matter content and their over maturity resulting from great burial depth (more than 7630 m). Other Paleozoic strata, except the Lower Devonian Ayitepesi Formation, generally have the values of more than 0.5% TOC. Organic matter of the Middle Devonian Safaktepesi sediments are composed of highly terrestrial organic material (type III kerogen), while samples from other three formations (Gumusali, Ziyarettepe and Yigilitepe Formations), while samples from other organic matter (type II and type III kerogen). The average TAI values are as high as 3.4 (equivalent to 1.42 of R₀%) for Ayitepesi and as low as 2.75 (equivalent to 0.77 of R₀%) for Yigilitepe Formations. Time-temperature index values (TTI) indicate that Ziyarettepe and Yigilitepe sediments are marginally mature to mature, while the Devonian strata are overmature. There are minor discrepancies between ΣTTI values and geochemical data in terms of the organic maturity for Devonian strata. In contrast, the e is a consistency between those values for the Ziyarettepe and the Yigilitepe Formations. The onset of oil generation time in the region was initiated from as early as the Norian (216 Ma) to as late as the Lutetian (45 Ma).Regional variations in the level of thermal and source-rock maturities of the Upper Paleozoic sediments in the eastern Taurus region largely depend on burial depth.