Impact of the Dead Sea Transform Kinematics on Adjacent Volcanic Activity

The Dead Sea Transform (DST) cuts through the northwestern edge of the Harrat ash Shaam volcanic field of western Arabia. The relation of the DST to adjacent volcanic activity has varied during the last 5 Ma. While Pliocene volcanism erupted on both shoulders of the DST and thick sections of volcanics accumulated along its axis, Pleistocene volcanic activity gradually abandoned the transform area while continued farther east. This was concomitant with the increase of transform-normal (E-W) contraction along the adjacent transpressive Metulla block at the DST northern sector. New geochronology of Pleistocene volcanic rocks from the Golan Heights (Ar-Ar) and of syntectonic and post-tectonic calcite precipitates (U-Th) from Metulla block reveals temporal association of volcanic dormancy and intensity of the transpressive regime. This includes volcanic cessations during 600–220 ka and post 100 ka, which coincided with growth episodes of several ~E-W striking veins within the adjacent Metulla block. New high-resolution U-Th ages of calcite-filled vein record the exact timing of these growth episodes to 340–240 and 53–16 ka, which is in accordance with the renewed activity along N-S strike-slip faults during 220–60 ka, manifested by U-Th ages of calcite precipitates on striated fault planes. The temporal association of volcanic dormancy and enhanced transpression, while volcanic activity and increased strike-slip activity, suggests that continental transforms may act both as inhibitors and as facilitators to magmatic activity. Switching between intermediate and least principal stresses might be the underline mechanism for stress dissipation and relaxation at a time scale of 100 ka.