Magnetic character of a large continental transform : an aeromagnetic survey of the Dead Sea Fault

Author Posting. © American Geophysical Union, 2007. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry Geophysics Geosystems 8 (2007): Q07005, doi:10.1029/2007GC001582.New high-resolution airborne magnetic (HRAM) data along a 120-km-long section of the Dead Sea Transform in southern Jordan and Israel shed light on the shallow structure of the fault zone and on the kinematics of the plate boundary. Despite infrequent seismic activity and only intermittent surface exposure, the fault is delineated clearly on a map of the first vertical derivative of the magnetic intensity, indicating that the source of the magnetic anomaly is shallow. The fault is manifested by a 10–20 nT negative anomaly in areas where the fault cuts through magnetic basement and by a <5 nT positive anomaly in other areas. Modeling suggests that the shallow fault is several hundred meters wide, in agreement with other geophysical and geological observations. A magnetic expression is observed only along the active trace of the fault and may reflect alteration of magnetic minerals due to fault zone processes or groundwater flow. The general lack of surface expression of the fault may reflect the absence of surface rupture during earthquakes. The magnetic data also indicate that unlike the San Andreas Fault, the location of this part of the plate boundary was stable throughout its history. Magnetic anomalies also support a total left-lateral offset of 105–110 km along the plate boundary, as suggested by others. Finally, despite previous suggestions of transtensional motion along the Dead Sea Transform, we did not identify any igneous intrusions related to the activity of this fault segment.The project was funded by U.S.-AID Middle Eastern Regional Cooperation grant TA-MOU-01-M21-012

Effects of Cretaceous plume and convergence, and Early Tertiary tectonomagmatic quiescence on the central and southern Levant continental margin

<p>This study synthesizes geological and geophysical evidence concerning the structure and character of the central and southern Jurassic Levant continental margin during Cretaceous–Tertiary time. From the beginning of the Cretaceous and until Cenomanian time, the Levant margin was strongly affected by extensional tectonics, cyclical igneous activity and rifting coupled with thermal and vertical fluctuations. It is suggested here that during the Senonian–Maastrichtian convergence of Afro-Arabia and the Mesotethys, and the Tauride part of Eurasia, the Herodotus basin oceanic crust subducted along the Eratosthenes Arc, below the short-lived abandoned Levant back-arc basin. Such a plate configuration assumes regional shear zones, as follows: (1) between the Eratosthenes Arc from the south and the Kyrenia Arc from the north: the NW–SE Carmel–Azraq–Sirhan fault system; (2) between the Sinai and the African plates: the Suez fault system; (3) between the Mesotethys and the African plates: the northern Egypt–Sinai–Negev west–east transversal fault system. Distinct tectonomagmatic quiescence between Late Maastrichtian and Late Eocene time allowed thermal relaxation and subsidence of the Levant margin until the apparent achievement of local isostatic compensation and the consequent development of the longest transgression over the Afro-Arabian ramp. </p