Architecture of tectonic and crustal structure of the Middle Marmara Sub-basin and its surroundings using gravity data


Parlak A. Y., Elmas A.

Carbonates and Evaporites, vol.38, no.3, pp.1-12, 2022 (Peer-Reviewed Journal)

  • Publication Type: Article / Article
  • Volume: 38 Issue: 3
  • Publication Date: 2022
  • Journal Name: Carbonates and Evaporites
  • Page Numbers: pp.1-12
  • Karadeniz Technical University Affiliated: Yes

Abstract

To study the tectonic and crustal structure of the Middle Marmara Sub-basin and its surroundings, gravity data obtained from

the Earth Gravitational Model (EGM08) were analyzed using Radially Averaged Amplitude Spectrum, Total Horizontal

Derivative (THD), Parker-Oldenburg (PO) inversion, Normalized Full Gradient (NFG) and Isostatic Analysis techniques.

While positive gravity anomalies are observed on the Çınarcık and West Marmara sub-basins on the Marmara Sea Basin, the

reason for the negative gravity anomalies observed on the Middle Marmara Sub-basin is one of the objectives of this study.

Moreover, the earthquake epicenters are concentrated in the central part of the Main Marmara Fault (MMF) on the Middle

Marmara Sub-basin, while sparse in the eastern part of the MMF in the eastern part of the sub-basin. To investigate the causes

of these, first of all, the average depth values of the in-sediments, basement, Conrad and Moho discontinuities of the study

area were calculated using the radially averaged amplitude spectrum of the Bouguer gravity data. The THD technique was

used to display the discontinuity limits at different levels. As a result of the THD calculations, the continuity of the MMF in

Middle Marmara Sub-basin could not be observed as a strait fault. It has been interpreted that this fault consists of a series

of small faults in this area. Also, the basement topography of the study area was calculated with the inverse solution, hence

basement depth varies between 2.8 and 7.4 km. The differences between the Gravimetric Moho and the Isostatic Moho

were calculated, and areas with high and low seismic activity were mapped. With this study, it has been concluded that the

equilibrium state of the crust has not yet formed around the Middle Marmara Sub-basin and its surroundings. Moreover, the

negative gravity anomalies are caused by the collapse of the crust around this sub-basin.