AAPG Middle East Region Geoscience Technology Workshop

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The South Oman Western Deformation Front Formation: A Mechanism to explain how Halokinesis can be Paused in Time and Space


The South Oman Salt Basin (SOSB) is an unusual petroleum-producing domain with substantial hydrocarbon fields varying from self-charging Precambrian carbonate stringers embedded in Precambrian Ara salt to numerous Paleozoic post-salt clastic reservoirs. Its western margin is formed by the so called “Western Deformation Front”, a structurally complex zone. Historically, due to the poor seismic imaging and limited amount of data, the western deformation front has been interpreted as an extensional passive margin or as compressional or transpressional belts. Newly acquired and reprocessed seismic data have recently permitted improved imaging of the sub-surface, and a transpressional nature is now the preferred interpretation of the Western Deformation Front. One striking observation, revealed by the improved seismic quality, has been how much the Angudan unconformity has been deformed by rejuvenation of halokinesis, after a significant pause in salt movement. This faulting of the unconformity is intriguing because the seismic images indicate that the amount of salt and differential loads present at the time should have prevented any pause in the halokinesis. In this paper, we will present a potential explanation for the pause of the halokinesis. The pause is interpreted to be linked to the compressional stress generated during the transpressional deformation associated with the formation of the Western Deformation Front with its apex at Angudan time. We will present the seismic evidence as well as a sandbox analogue illustrating a similar mechanism in delta tectonics in a compressional setting.