Moho depth and crustal thinning in the Marmara Sea region from gravity data inversion

J. Kende*, P. Henry, G. Bayrakci, M. S. Özeren, C. Grall

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

22 Citations (Scopus)

Abstract

The free-air gravity in the Marmara Sea reveals that the low density of sedimentary basins is partly compensated in the lower crust. We compiled geophysical upper crust studies to determine the sediment basin geometries in and around the Marmara Sea and corrected the gravity signal from this upper crust geology with the Parker method. Then, assuming long wavelength anomalies in the residual gravity signal is caused by variations in the Moho topography, we inverted the residual to build the Moho topography. The result shows that the Moho is uplifted on an area greater than the Marmara Sea with a maximum crust thinning beneath the basins where the Moho is at about 25 km, 5 km above the reference depth. We then evaluated the Neogene extension by comparing the surface covered by our 3-D thinned model with the surface covered by an unthinned model with same crustal volume. Comparing this surface with areal extension rate from GPS data, we found a good compatibility indicating that the extension rate averaged over the Sea of Marmara area probably remained close to its present-day value during major changes of tectonic regime, as the incursion of the North Anatolian Fault system during the Pliocene leads to the establishment of the dominantly strike-slip present-day system. We also show that crustal extension is distributed over a wider domain in the lower crust than in the upper crust, and that this may be accounted for by a relatively minor component of lower crustal ductile flow.

Original languageEnglish
Pages (from-to)1381-1401
Number of pages21
JournalJournal of Geophysical Research: Solid Earth
Volume122
Issue number2
DOIs
Publication statusPublished - 1 Feb 2017

Bibliographical note

Publisher Copyright:
©2016. American Geophysical Union. All Rights Reserved.

Funding

This work was funded by Marsite FP7 EU project, by COST action FLOW, and by INSU support fund for scientific cruises. We thank the GENAVIR crew during the Marsite cruise as well as the scientific team for their help and time spent on discussions and explanations during onboard operations. Special thanks to Patrick Le Roy for his detailed presentation of the N/O Pourquoi Pas? equipment. We thank Hayrullah Karabulut, Louis Geli, Celal Şengör, and, more particularly, Xavier Le Pichon for discussions and constructive comments on the manuscript. The satellite gravity data are available on the Scripps Institution of Oceanography (University of California San Diego) website (http://topex.ucsd.edu/index.html), and gravity data retrieved by the N/O Pourquoi Pas? gravimeter are available on the IFREMER data repository website (http://data.ifremer.fr/). All other sources used to build the geological model are published and referenced in the manuscript. Input files necessary to reproduce the model are available from the authors upon request ([email protected]).

FundersFunder number
INSU
University of California, San Diego
Seventh Framework Programme308417
European Cooperation in Science and Technology

    Keywords

    • extension
    • gravity inversion
    • Moho topography
    • Sea of Marmara
    • strike-slip basin

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