Abstract

In the Arabian-Northern African region, interaction of the Nubian, Arabian and Eurasian plates and many small tectonic units is conspicuous. In order to better understand this interaction, we use satellite derived gravity data (retracked to the Earth’s surface) recognized now as a powerful tool for tectono-geodynamic zonation. We applied the polynomial approximation to the gravity data which indicated the presence of a large, deep ring structure in the eastern Mediterranean centered below the Island of Cyprus. Quantitative analysis of residual gravity anomaly provides an estimate of the deep anomalous body’s upper edge at a depth of about 1700 km. Computations of the residual gravity anomalies for the lower mantle also indicate presence of anomalous sources. The GPS vector pattern coinciding with the gravity trend implies counter clockwise rotation of this structure. Independent analyses of the geoid isolines map and seismic tomography data support the existence of a deep anomaly. Paleomagnetic data analysis from the surrounding regions confirms a counter clockwise rotation. Numerous petrological, mineralogical, geodynamical and tectonic data suggest a relation between this deep structure and near-surface processes. This anomaly sheds light on a number of phenomena including the Cyprus gravity anomaly, counter clockwise rotation of the Mesozoic terrane belt and asymmetry of basins along continental transform faults.

Highlights

  • Understanding the relationship between deep geodynamics and subsurface geological processes is one of the prime challenges in Solid Earth Sciences [1] [2]

  • The region is located in the junction zone between East Gondwana and Eurasia, the geological-geophysical instability of which is determined by the intensity of geodynamics—both collisional and rift spreading

  • At present, based on the GPS, paleomagnetic and seismic data analysis we propose that such a behavior of geoid isolines is caused by the integrated effect of the earlier recognized Ural-African Step and large anomalous source occurring at a great depth (GDRS)

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Summary

Introduction

Understanding the relationship between deep geodynamics and subsurface geological processes is one of the prime challenges in Solid Earth Sciences [1] [2]. We present a combined analysis of the northern Africa-eastern Mediterranean area, where large tectonic plates (Nubian, Arabian and Eurasian) and a number of comparatively small tectonic plates interact [3] This ~24 million km region (Figure 1) includes active rifts and collision belts, a complex pattern of continental and oceanic crusts of different ages, intense seismic activity, as well as several high-amplitude gravity anomalies and seismic velocity anomalies observed at great depths. The eastern Mediterranean is a tectonically complex region evolving in the midst of the progressive Afro-Eurasian collision The combination of these geological-geophysical elements requires a structural-geodynamic analysis using modern methodological and numerical methods.

Examination of Satellite Derived Gravity Data
Polynomial Approximation
Quantitative Analysis of the Residual Gravity Anomaly
Computations of Residual Gravity Anomalies for the Lower Mantle
Brief Analysis of Geoid Data
Integrated Analysis of Geophysical and Geological Factors
Discussion
Conclusions
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