קולוקוויום בחוג לגאופיזיקה: A giant mantle quasi-ring counterclockwise rotating structure beneath the Eastern Mediterranean and its reflection in geophysical fields and geological features

Zoom: https://tau-ac-il.zoom.us/j/86769967727?pwd=25OfJE7Na6lWggNsBNRbl7H8bnW56x.1

Abstract:

The tectonic-geodynamic characteristics of the North African–Arabian region are complex, driven by interactions among numerous factors. To study this interaction, we primarily used satellite gravimetric data (retracked to the Earth’s surface), widely recognized as a powerful tool for tectonic–geodynamic zoning. The applied polynomial averaging of gravity data revealed a large, deep quasi-ring structure in the Eastern Mediterranean, centered beneath the island of Cyprus. These data are consistent with the available counterclockwise GPS data pattern and the regional distribution of paleomagnetic data. Simultaneously, the geometrical center of the revealed structure coincides with the Earth’s critical latitude of 35°. A quantitative interpretation of the residual satellite gravity anomaly yields a mass center at a depth of about 1450 km. Additional confirmation is provided by the anomalies in the regional magnetic field Δ distribution, reduced to a height of 2.5 km above sea level. Based on the detailed paleomagnetic analyses, the average rotation rate of Cyprus under the influence of the deep structure over the past 70 Ma is estimated. The authors have compiled a paleobiogeographic map showing the counterclockwise displacement of the typical Ethiopian fauna to the northwest. The influence of the rotating deep structure on stress in the overlying blocks of the Earth’s crust and lithosphere is shown before the destructive earthquakes with magnitudes = 7.9 and = 7.8 that occurred on February 6, 2023, in Turkey. The available seismic tomography profiles enabled the construction of a seismotomographic scheme to locate the deep structure. This scheme aligns with analyses of satellite gravity and marine/terrestrial gravity studies, geoid anomalies, magnetic anomaly distributions, paleomagnetic data, regional GPS vector directions, seismological and tectonic-structural data, and mineralogical and petrological data. The combined evidence from these factors is compelling and confirms the existence of an anomalous deep-rotating structure beneath the Eastern Mediterranean and adjacent regions. The deep structure also sheds light on specific anomalous effects in the upper crust, including the counterclockwise Cyprus rotation, high-intensity Cyprus gravitational anomaly, the configuration of the Sinai Plate, the identification of an ancient oceanic crust block in the Eastern Mediterranean, the counterclockwise rotation of the Mesozoic terrane belt, and the asymmetry of sedimentary basins along continental faults.

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מארגן האירוע: ד"ר ליאור רובננקו