Günay Çifci - Academia.edu (original) (raw)

Papers by Günay Çifci

Marine Georesources & Geotechnology, 2009

High-resolution seismic survey and sediment core sampling were conducted to investigate acoustic ... more High-resolution seismic survey and sediment core sampling were conducted to investigate acoustic characteristics of gas-bearing sediments in Jinhae Bay, the southeast of Korea. The sediment in Jinhae Bay is mostly homogenous mud deposited after the Holocene transgression. Along with the 410 km of chirp seismic profiling, five piston core samples were collected on the track lines.Gassy sediments are common and occur

Marine and Petroleum Geology, Mar 1, 2016

Abstract This study includes the interpretation of submarine morphological structures using the m... more Abstract This study includes the interpretation of submarine morphological structures using the multibeam echo sounder bathymetry and CHIRP high resolution seismic in the Gulf of Izmir. The faults as the indicator of active tectonics, submarine channels, gas seeps, active and inactive pockmarks are the main natural morphological features in the gulf. Additionally, man-made (anthropogenic) structures like navigation channels, excavation debrises and ships wrecks are also observed. Geomorphological development of the gulf is controlled by the active faults in the Neotectonic period. Therefore, detection of active faults is very critical for the morphology of the gulf where many faults with different orientations have been interpreted on the seismic data. In the central-outer part of the gulf to the W NW, there are some normal faults trending in the N NW and S SE direction, and in the eastern and southern part of the gulf, E–W trending normal faults are evident in the seabed topography. The water depth increases from the eastern (inner) to the outer section of the gulf in the W NW direction. The N NE margin and the coastal area are very shallow (

Springer eBooks, Aug 19, 2013

Tectonophysics, May 1, 2014

EGUGA, Apr 1, 2012

ABSTRACT The Black Sea has a narrow shelf and steepy continental slope at southern side. Recent s... more ABSTRACT The Black Sea has a narrow shelf and steepy continental slope at southern side. Recent studies show the active sedimentary processes sediment transportation from shelf to abyssal depths. Study area is located in the central Black Sea Turkish continental slope and is under compressional tectonic regime of Western Pontides. A total of 1950 km of high resolution multichannel seismic reflection, Chirp sub-bottom profiler and multibeam bathymetry data were collected offshore of Zonguldak from continental shelf to abyssal plain of Black Sea along the margin. We used 216 channel 1350 m long digital streamer and a 45+45 cubic inch Generator-Injector (GI) gun fired at every 25 m. Chirp sub-bottom profiler system has 9 transducers operating at 2,7-6,7 kHz frequency band with 3,5 kHz central frequency. Side mounted multibeam bathymetry system has 50 kHz transducers with 153 degrees max. swath width. Southern Black Sea has a very narrow shelf and a very steep continental slope. Both seismic and bathymetry data show that the shelf break in the study area is located at a water depth of about 100 m and continental slope deepens to 2200 m maximum water depths of the abyssal plain with a maximum slope of about 27 degrees. The acoustic data also show that there are significant erosional structures along the margin especially on the continental slope and rise offshore of Zonguldak. An unstable area in the NW consisting of relatively larger slides and buried debris lobes is named Amasra mass failure zone. Different type of sliding with varying sizes including sliding in the steep slope zones, smaller-scale slides on the canyon walls, and relatively larger slides exist in the Amasra mass failure zone. We suggest that the slides in the Amasra mass failure zone is possibly triggered by excess pore pressures in shallow sediments due to the submarine fluid flow possibly produced from gas hydrate dissociation. Warmer Mediterranean water transportation during the rapid transgression period after the last glacial maximum in the Black Sea together with the rapid sedimentation possibly resulted in a destabilization of gas hydrates, which caused excess pore pressures in shallow sediments followed by sediment failures. A conceptual model together with phase curves for the gas hydrate stability in the area is produced to explain the formation of larger slides in the Amasra mass failure zone by excess pore pressures due to local gas hydrate dissociation and fluid flow. Small-scale normal faults around these type of sedimentary structures are also observed and we suggest that these faults are also secondary factor promoting the failures providing the suitable pathways for fluid flow as well as the suitable weak surfaces for the sliding. Several small-scale debris lobes are observed on the apron side and abyssal plain of the study area. Seismic data also show slab-type sliding on the upper continental slope to the south, whereas block-type sliding is formed by rotational faults on the canyon walls. Both types of mass wasting occur in the area due to gravitational loading on the steep slope zones possibly triggered by local seismic activity. * This presentation was supported by the EUROCORES programme TOPO-EUROPE of the European Science Foundation

AGU Fall Meeting Abstracts, Dec 1, 2016

Jeofizik Dergisi, Jun 1, 1996

Геология и полезные ископаемые мирового океана, 2021

It has been suggested that shelf and slope sediments of high deposition rate are methane sources,... more It has been suggested that shelf and slope sediments of high deposition rate are methane sources, whereas the deep basin is methane sink. The methane production and migration in sediments may cause massive slope failures so methane is geologically important. Methane production is also economically important as methane seeps may indicate the presence at depth of hydrocarbon reservoirs, and methane hydrate may be an important source of energy. Recent studies in marine geology indicate potential geo-resources in the Turkish coast of Black Sea. The Black Sea sediments are rich in calcite and organic carbon, the latter showing a high degree of preservation due to anoxia in the waters below 100-150 m. Different marine geophysical surveys at different times were carried out in order to understand the sedimentary features of gas-saturated sediments in the Black Sea. Multibeam, side scan sonar, sub-bottom profiler and multi-channel seismic data were collected to make both high-resolution bathymetric and reflectivity maps of the seafloor. In some cruises, deep-tow combined side scan sonar and subbottom profiler was used to obtain acoustic images of both the seafloor surface and subbottom sediments. Several different structures were observed in the Black Sea basin as slumps, pockmarks, faults, gas chimneys, shallow gas accumulations and dome-like structures. Structures, which contain gas hydrates, are present on the seismic sections as strong acoustic reflections.

EGU General Assembly Conference Abstracts, May 1, 2014