History of faulting and magmatism in the Galilee (Israel) and across the Levant continental margin inferred from potential field data

Abstract

The Galilee study area, northern Israel, is at present an uplifted, steep continental margin that formed mainly during the Jurassic and has a large positive isostatic anomaly. Since the Jurassic, it was modified by several tectonomagmatic events, which this study attempts to define and classify by updating, reprocessing and reinterpreting gravity, aeromagnetic and geological data. The prominent Rehovot-Carmel N–S positive reduced-to-pole (RTP) magnetic anomaly caused by the Gevim Volcanics, as well as the coexisting Helez-Gaash high Bouguer gravity and the Pleshet low Bouguer gravity, represent the deep (>5 km) Permo-Triassic dominant horst and graben structure of Israel. The Jonah Ridge and Beirut high SW–NE RTP magnetic anomalies in the Levant basin delineate the Levant continental edge that is marked by a deeply buried horst covered by a Late Cretaceous volcanic complex. The Asher and Devora Jurassic volcanics appear to be responcible for the Atlit and Galilee negative magnetic anomalies and for significant negative gravity anomalies which became clear after removing gravity effect of the upper (post-Turonian) light density sediments from the observed gravity. The volcanics extend along a SW–NE belt parallel to the strike of the Moho. It is suggested here that the Carmel-Gilboa fault propagated during the Late Cretaceous from the Levant basin across the Galilee area southeastward to form the Azraq-Sirhan graben in Jordan. As such, it forms a right-step, en echelon, dextral strike-slip fault with associated tectonic basins of various shapes. During the Oligocene and before formation of the Dead Sea transform (DST), the reactivation of the Azraq-Sirhan graben was accompanied by tectonic driven rift propagation in the opposite direction, from Azraq-Sirhan to northwest. It dispersed into many faults and terminated ∼10 km west of the present DST. During the Miocene it propagated in the same direction and includes internal volcanic activity. The numerous Miocene-Pliocene volcanic centers on the margins of the DST indicate that the preferred pathway for magmas at that time was not within the deep basins of the DST.