Detailed structure of the crust and upper mantle along the Jordan‐Dead Sea Rift

Abstract

Seismic refraction data shot along the Dead Sea‐Gulf of Elat graben were reevaluated. Travel times and amplitudes of first arrivals and later arrivals of both refracted and reflected phases were studied using true amplitude record sections and synthetic seismogram sections. The computed models show that the crust is divided by a discontinuity into a uniform velocity upper crust and a higher velocity lower crust. Along the graben the lower crust is separated from the upper mantle by a 5‐km‐thick transition zone in which the velocity increases rapidly and smoothly. This transition zone is not present away from the rift valley. The crustupper mantle boundary dips to the north along the Gulf of Elat to the Dead Sea. A discontinuity was found at a depth of 55 km within the upper mantle, below which the velocity increases from 8.0 to 8.6 km s−1. The results indicate an intermingling of upper mantle material with lower crust material along the graben. The upwelling increases in its vertical extent as the Red Sea with its active spreading mechanism is approached.