CRUSTAL STRUCTURE OF THE EASTERN PROVINCE OF SAUDI ARABIA DEDUCED FROM GRAVITY DATA

Gravity modeling technique has been applied for the eastern province of Saudi Arabia to estimate both the thickness of the crust and crustal structures, based on the average densities for these structures and their depths. These models have been prepared depending on the analysis of gravity field measurements at the study area. Seven cross-sections have been selected along the complete Bouguer anomaly map. Modeling has been carried out using GMSYS-2D software. Matching process between the measured and calculated gravity values has been carried out during modeling taking into consideration the available geological maps and the previous studies. The proposed models indicate that the earth's crust is composed of three main layers as follows; upper crust of thickness ranging between 3.2 and 13 km with gradual increasing towards the east; Middle crust extends to depth from 13 to 29 km; and the lower crust with depth ranges between 29 and 49 km, where the Moho discontinuity, which separates crust from the upper mantle, is reached. The thickness of the crust ranges from 40 to 49 km. The greater thickness of the earth's crust reaches 49 km in the northern part of the study area, while decreasing gradually to reach 40 km in the southern and southwestern parts of the area.
According to these models it can be concluded that, the thickness of the crust in the eastern province decrease gradually towards the Arabian shield in the west and the Arabian Gulf in the east. This suggests that, the Arabian Peninsula lies between two major tectonic boundaries that have great impact on the creation of the subsurface geological structures. One of the most important results that have been reached is the ability of gravity measurements to providing us with the clear perception for the changing of crustal structures and how these changes occurred