High Structures in the Levant basin
Recent giant gas discoveries within deeply buried structural highs in the middle of the Levant basin have attracted the attention of the industrial and academic communities striving to understand the origin of these structures, their relations with the tectonic history of the basin, and their evolution through time. What is the origin of the deeply buried structures in the basin? Are they related to the Early Mesozoic rifting or to the Late Mesozoic – Early Tertiary Africa-Eurasia convergent phase? How are the structures in the basin related to the closure of the Tethys Ocean, to the onshore Syrian Arc fold belt, and the Dead Sea transform?
The enigma of the Jonah high in the middle of the Levant basin and its significance to the history of rifting
Here we focus on the Jonah high, which is one of the largest structures in the basin and is particularly enigmatic in its geometry, dimensions and location compared to nearby structures. It is buried under more than 3 km of Late Tertiary sediments, and is associated with one of the largest magnetic anomalies in the basin, though no significant gravity anomaly is observed. Previous studies raised several possibilities explaining its origin: an ancient horst related to the early stage of basin formation (Late Paleozoic or early Mesozoic); a Syrian Arc fold (Late Cretaceous to Neogene); a giant volcanic seamount; and an intrusive magmatic body. A reconstruction of the evolution of this structure is proposed here based on newly produced pre-stack depth migration of five selected seismic reflection lines crossing the Jonah high combined with a basin-wide interpretation of more than 500 2-D time-migrated lines. We suggest that the Jonah high is a horst bounded by grabens, most probably formed during continental breakup related to the Neo-Tethys formation. However, unlike other extensional structures that were reactivated and inverted during the Syrian Arc deformation, the Jonah high was never reactivated. Rather, it formed a prominent seamount that persisted for 120–140 Ma until the Early Miocene, when it was finally buried. In a wider perspective the Jonah horst is similar to the Eratosthenes seamount, a fragment of continental crust between the Levant and Herodotus basins.
Sagy. Y., Gvirtzman, Z., Reshef, M., Makovsky. Y., 2015. The Enigma of the Jonah high in the Middle of the Levant Basin and its Significance to the History of Rifting,
Tectonophysics 10/2015; DOI:10.1016/j.tecto.2015.09.037
80 m.y. of folding migration: New perspective on the Syrian arc from Levant Basin analysis
A series of elongated folds known as the Syrian arc fold belt developed throughout the Levant region alongside the Tethys closure. This compressional belt followed a preexisting extensional belt that had formed 100–200 m.y. earlier alongside the Tethys opening. Here we analyze a series of Syrian arc–type folds deeply buried in the Levant Basin 50–200 km away from the onshore Syrian arc mountain ridge. The continuous stratigraphic section in the Levant Basin provides a complete record of folding, which is incomplete onshore. We show that folding continued 80 m.y. in the same direction regardless of major tectonic processes that occurred in the surrounding areas. During this period, Africa rotated ~20° counterclockwise and started colliding with Eurasia, Arabia broke off Africa, and subduction initiated under Cyprus. But despite all of these surrounding processes, the direction of folding in the Levant remained nearly constant (relative to Africa). We suggest that the main control on folding direction is inherited extensional structures formed along Africa’s margin during Tethys opening and that continuously rotate with it. However, the surrounding tectonic processes, which had minor influence on folding direction, did affect folding intensity and its spatial distribution. Folding ceased in the northwest part of the basin in the Oligocene, peaked in the entire basin during the early Miocene coeval with the Red Sea–Gulf of Suez rifting and convergence of Arabia with Eurasia, and has gradually decreased since the late Miocene, concurrently with the major activity along the Dead Sea transform.
Sagy. Y., Gvirtzman, Z., Reshef, 80 m.y. of folding migration: New perspective on the Syrian arc from Levant Basin analysis, Geology, doi.org/10.1130/G39654.1
