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Possible Impact Structures in the Sedimentary Basins of Saudi Arabia

Neville, Allen S.1; Afifi, Abdulkader M.1; Cook, Douglas *1
(1) Area Exploration, Saudi Aramco, Dhahran, Saudi Arabia.

Five isolated circular structures in the subsurface of the Arabian platform are identified as possibly due to meteorite impacts. Three of these structures (Saqqar, Jalamid, and Banat Baqar) are located in northern Arabia in the Nafud basin, while the Hamidan and Zaynan structures are located in southern Arabia in the Rub’ Al Khali basin. On seismic data, these structures appear as circular features with central uplifts surrounded by circular rims whose diameters range between 4 and 30 kilometers. The structural deformation of the central uplift decreases and disappears with depth. In addition, three of these structures have circular magnetic and/or gravity anomalies. Initial study of samples from wells drilled in three of these structures did not reveal evidence of shock metamorphism except for possible planar deformation lamellae in quartz from a core in the Saqqar structure. Their geologic setting makes it unlikely that these structures formed as salt diapirs, mud diapirs or magma intrusions, and an impact origin is the most plausible cause for their formation. The location (latitude and longitude) and inferred age of the possible impact structures follows:

Saqqar- 29° 32’ N, 38° 40’ E, Post Devonian;

Jalamid- 31° 28’ N, 39° 35’ E, Llanvernian;

Banat Baqar- 29° 06’ N, 37° 36’ E, Llanvernian;

Hamidan- 20° 38’ N, 54° 43’ E, Neogene;

Zaynan- 20° 23’ N, 50° 09’ E, Jurassic.

 

AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California