Geophysical images of the Dead Sea Transform in Jordan reveal an impermeable barrier for fluid flow

Abstract

[1] High-resolutionseismictomography and magnetotelluric (MT) soundings of the shallow crust show strong changes in material properties across the Dead Sea Transform Fault (DST) in the Arava valley in Jordan. 2D inversion results of the MT data indicate that the DST is associated with a strong lateral conductivity contrast of a highly conductive layer at a depth of approximately 1.5 km cut-off at a position coinciding with the surface trace of the DST. At the same location, we observe a sharp increase of P wave velocities from <4 km/s west of the fault to >5 km/s to the east. The high velocities in the east probably reflect Precambrian rocks while the high electrical conductivity west of the DST is attributed to saline fluids within the sedimentary filling. In this sense, the DST appears to act as an impermeable barrier between two different rock formations. Such a localized fluid barrier is consistent with models of fault zone evolution but has so far not been imaged by geophysical methods. The situation at the DST is remarkably different from active segments of the San Andreas Fault which typically show a conductive fault core acting as a fluid conduit. INDEX TERMS: 1515

Different styles of faulting deformation along the Dead Sea Transform and possible consequences for the recurrence of major earthquakes

“…9b). This is supported by results of conductivity studies across the AF, which suggest that the fault does presently not act as a fluid conduit (Ritter at al., 2003). One may reason that the earthquake recurrence interval on a fault segment that recovers after an earthquake without fluid assisted healing (e.g.…”

“…Using these results, the DST can be qualitatively compared to other major strike-slip faults (e.g., Ritter et al, 2003;Haberland et al, 2003;Janssen et al, 2004;DESERT 2004).…”

Crustal metamorphic fluid flux beneath the Dead Sea Basin: constraints from 2-D and 3-D magnetotelluric modelling

“…Ritter et al 2003Ritter et al , 2005Unsworth & Bedrosian 2004;Tank et al 2005;Thiel et al 2009;Becken et al 2011;Desissa et al 2013). The geometry and the overall conductance of FZCs depend on local geological, hydrogeological conditions and the geodynamic (tectonic) setting of a fault (see Unsworth & Bedrosian 2004;Ritter et al 2005, and references therein.).…”

“…Deep magnetotelluric (MT) sounding data were collected in the framework of DESERT project along a long and several shorter profiles across the DST (Araba fault), approximately 150 km to the south of the DSB (Ritter et al 2003). Ritter et al (2003) argued that the shear zone at this particular location of the Araba fault may be exceptionally narrow (in the range of a few metres), beyond the lateral resolution threshold of MT measurements. Instead, the inversion models were indicative for a fault acting as an impermeable barrier for cross-fault fluid transport.…”

“…TEM and DC geo-electric) have been applied on either side of the rift valley to investigate the hydrological system, particularly to delineate the saline/fresh water interface close to the Dead Sea (Kafri et al 1997;Salameh & E.-Naser 2000;Yechieli et al 2001;Kafri & Goldman 2005;Yechieli 2006;Meqbel et al 2013). Deep magnetotelluric (MT) sounding data were collected in the framework of DESERT project along a long and several shorter profiles across the DST (Araba fault), approximately 150 km to the south of the DSB (Ritter et al 2003). Ritter et al (2003) argued that the shear zone at this particular location of the Araba fault may be exceptionally narrow (in the range of a few metres), beyond the lateral resolution threshold of MT measurements.…”