Date

2014-03-14

Author

Cambazoğlu, Selim
Yal, Gözde Pınar
Eker, Arif Mert
Koçkar, Mustafa Kerem
Osman, Şen
Akgün, Haluk

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This study encompasses the detection, mapping and validation of hydrothermal alteration types and minerals, surface temperature anomaly mapping utilizing remote sensing methods in order to assess the geothermal potential of the Dikili region. The study area covers Bergama, Dikili, Çandarlı and Altınova districts located at the northern part of İzmir Province where fumaroles and numerous thermal water outflows with temperatures between 63°C and 89°C are present. The study area is located at the northern part of Aegean Region. It is a tectonically very active area under the control of the extensional regime. ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) satellite images which includes 3 bands at visible near infra-red bandwidth, 6 bands at short wave infra-red wavelength and 5 bands at thermal infra-red wavelength range was used for the alteration mapping of the study area. The purpose of this study is to correlate the geothermal anomalies with thermal springs, geological units and lineaments and to prepare a relative surface temperature map and the alteration zones to determine the geothermal anomalies utilizing the ASTER image of the area. Within the context of geothermal potential assessment, the studies in order to detect and identify the alteration minerals are performed since these alteration minerals provide information on formation temperatures. Even though the ASTER sensor does not have a very high spectral resolution, its ability to acquire images at short wave infra-red and thermal infra-red wavelength regions along with the visible near infra-red range, makes it capable of mapping the minerals. In this study, Normalized Difference Vegetation Index (NDVI) and water body masking was applied on the ASTER image. In the first part of the study an alteration map of the region produced by JICA was used to obtain information on the expected alteration types and minerals prior to image processing and for the validation of the spatial distribution of the identified alteration zones. This map was generated by using field and laboratory studies including X-Ray Diffraction (XRD) analysis performed on the samples collected from the field. Alteration types detected by JICA was classified and mapped as; silica mineral type, alunite mineral type, kaolinite-pyrophillite and alumino-clay type. Band ratios, various image composite images, Crosta technique and spectral mapping methods were performed by considering the spectral signatures of the expected hydrothermal alteration minerals in the study area. The alteration map generated by the assessment of the produced mineral maps, was correlated by the validation map of the area, therefore, a spatially more detailed alteration map was obtained. In the second part of the study, the performed analysis consists of processing the day-night image pair as well as the continuous temperature measurements collected from the field. Firstly, the necessary corrections required to remove the albedo effect which occurs due to differential heating of different materials (or cool down during night-time) were performed. For this purpose, the Digital Elevation Model produced from the 1/25.000 scaled topographical maps was used to generate a shaded-relief map. Furthermore, the reflection images for the first three bands of the daytime image at visible near infra-red wave length were generated by applying atmospheric correction. These reflection images along with shaded-relief (slope factor) image were used to create an albedo image and finally the daynight image pair was corrected by utilizing all these images according to simplified heat energy approach. Further, 24 hour in-situ continuous temperature measurements were utilized in order to remove the thermal inertia effect. Finally, the relative surface temperature map and alteration mineral map developed were correlated with the known geothermal manifestations, distributions of faults and lineaments and geological forms and units within a GIS environment.

Subject Keywords

ASTER,, Surface Temperature,, Hydrothermal Mineral Alteration,, Geothermal Energy,, Izmir

URI

https://hdl.handle.net/11511/81977
https://www.researchgate.net/publication/262567704

Collections

Department of Geological Engineering, Conference / Seminar