Heterogeneous structure of the lithosphere in the Black Sea from a multidisciplinary analysis of geophysical fields

T Lebed,O.V Legostaeva,I.B Makarenko,O.M Rusakov,A Savchenko,R.I Kutas,I.K Pashkevich,V I Starostenko

doi:10.24028/gzh.0203-3100.v37i2.2015.111298

T Lebed, O.V Legostaeva + Show 6 more

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https://doi.org/10.24028/gzh.0203-3100.v37i2.2015.111298

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Abstract

Magnetic, gravity, geothermal, seismic and tomographic data from the lithosphere were first jointly examined. A multidisciplinary interpretation has resulted in a new and consistent model for lithospheric density, magnetic, thermal and velocity heterogeneities. Faults of different orders for the crystalline crust have been mapped in details. Large deep fault zones were recognized. Among them is the most prominent Odessa-Sinop-Ordu (OSO) fault zone, which played a key role in the opening and development of the Black Sea Depression. A fundamental difference was revealed between the crustal and mantle structure and geophysical parameters of the Western Black Sea Basin (WBSB) and Eastern Black Sea Basin (EBSB). These dissimilarities are in the size of «non-granitic» crust, pattern and intensity of heat flow, topography of the lower boundary of the thermal lithosphere, mantle seismic velocity and structure of magnetic and residual gravity anomalies. Based on new information it was demonstrated that the WBSB and EBSB were diachronously formed on two large distinct continental blocks with independent post-rift development of the sub-basins. The rifting of the western sub-basin commenced earlier than that of the eastern one. The EBSB is characterized by younger thermal activity than the WBSB and consequently it was stabilized later. The Mid Black Sea High (MBSH) is not a single tectonic unit but is formed by two ridges of various crystalline crustal structure and age shifted relative to each other by the faults of the OSO zone.

Highlights

The interest in the Black Sea geology is determined by its key role in understanding the tectonic evolution of the middle Tethyan Realm and its hydrocarbon potential for the coastal countries
The purpose of this work is to present the results of the first joint interpretation of gravity and magnetic fields, heat flow and lithospheric seismic velocity and to shed new light on to the deep structure of the Black Sea Depression and coupling near-surface tectonics and lithospheric features at a regional scale
The mantle gravity component has been first estimated with an empirical relationship between density and Pwave velocity

Summary

Introduction

The interest in the Black Sea geology is determined by its key role in understanding the tectonic evolution of the middle Tethyan Realm and its hydrocarbon potential for the coastal countries. Despite abundant consideration that the Black Sea is a back-arc basin, there are still strong debates about the details of its origin and evolution [e.g. Zonenshain, Le Pichon, 1986; Finetti et al, 1988; Okay et al, 1994; Spadini et al, 1996; Cloetingh et al, 2003; Nikishin et al, 2003; Kutas, Геофизический журнал No 2, Т.

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