The northeastern Arabian passive margin is being subducted beneath the Zagros and Makran of Iran. A flexural bulge related to the weight of the Makran has migrated at 4 cm/a through the previously uplifted Hajar Mount...The northeastern Arabian passive margin is being subducted beneath the Zagros and Makran of Iran. A flexural bulge related to the weight of the Makran has migrated at 4 cm/a through the previously uplifted Hajar Mountains of Oman as this active convergence and collision between Arabia and Eurasia progresses, adding approximately another 500 meters of relief, and forming a series of uplifted marine terraces, alluvial terraces, and planation surfaces that record the passage of the bulge. We use a combination of field studies, remote sensing and GIS to map and better-understand these terraces, and elucidate how the tectonics of bulge migration, down-to-trench normal faulting, and eustatic sea level changes have interacted to produce the extant geomorphic features on the inner slope of the flexural bulge as it sinks into the foredeep of the Gulf of Oman. We speculate those terraces that were uplifted on the outer slope of the forebulge as it initially migrated through the passive margin （affected by ophiolite obduction in the Cretaceous） 3.75-7.5 Ma ago are now sinking on the inner slope of the forebulge （corresponding to the outer trench slope in the foredeep）, and have been partly covered by Quaternary marine terraces related to a Weichselian sea level high stand. Both the Tertiary and Quaternary terraces are cut by faults related to the active collision, confirming that there is a significant risk of moderate earthquakes in the region.展开更多
基金partially supported by Sultan Qaboos Internal (No.IG/SCI/ETHS/14/02)the National Natural Science Foundation of China (Nos.91014002 and 40821061)+2 种基金Ministry of Education of China (No.B07039)the Academic Innovation Base Plan of China University of Geosciences (Wuhan)the 1000 Talents Program,Central Organization Committee,China
文摘The northeastern Arabian passive margin is being subducted beneath the Zagros and Makran of Iran. A flexural bulge related to the weight of the Makran has migrated at 4 cm/a through the previously uplifted Hajar Mountains of Oman as this active convergence and collision between Arabia and Eurasia progresses, adding approximately another 500 meters of relief, and forming a series of uplifted marine terraces, alluvial terraces, and planation surfaces that record the passage of the bulge. We use a combination of field studies, remote sensing and GIS to map and better-understand these terraces, and elucidate how the tectonics of bulge migration, down-to-trench normal faulting, and eustatic sea level changes have interacted to produce the extant geomorphic features on the inner slope of the flexural bulge as it sinks into the foredeep of the Gulf of Oman. We speculate those terraces that were uplifted on the outer slope of the forebulge as it initially migrated through the passive margin （affected by ophiolite obduction in the Cretaceous） 3.75-7.5 Ma ago are now sinking on the inner slope of the forebulge （corresponding to the outer trench slope in the foredeep）, and have been partly covered by Quaternary marine terraces related to a Weichselian sea level high stand. Both the Tertiary and Quaternary terraces are cut by faults related to the active collision, confirming that there is a significant risk of moderate earthquakes in the region.
