Combining satellite and seismic images to analyse the shallow structure of the Dead Sea Transform near the DESERT transect

Abstract

The left-lateral Dead Sea Transform (DST) in the Middle East is one of the largest continental strike-slip faults of the world. The southern segment of the DST in the Arava/Araba Valley between the Dead Sea and the Red Sea, called Arava/ Araba Fault (AF), has been studied in detail in the multidisciplinary DESERT (DEad SEa Rift Transect) project. Based on these results, here, the interpretations of multi-spectral (ASTER) satellite images and seismic reflection studies have been combined to analyse geologic structures. Whereas satellite images reveal neotectonic activity in shallow young sediments, reflection seismic image deep faults that are possibly inactive at present. The combination of the two methods allows putting some age constraint on the activity of individual fault strands. Although the AF is clearly the main active fault segment of the southern DST, we propose that it has accommodated only a limited (up to 60 km) part of the overall 105 km of sinistral plate motion since Miocene times. There is evidence for sinistral displacement along other faults, based on geological studies, including satellite image interpretation. Furthermore, a subsurface fault is revealed %4 km west of the AF on two %E-W running seismic reflection profiles. Whereas these seismic data show a flower structure typical for strike-slip faults, on the satellite image this fault is not expressed in the post-Miocene sediments, implying that it has been inactive for the last few million years. About 1 km to the east of the AF another, now buried fault, was detected in seismic, magnetotelluric and gravity studies of DESERT. Taking together various evidences, we suggest that at the beginning of transform motion deformation occurred in a rather wide belt, possibly with the reactivation of older %N-S striking structures. Later, deformation became concentrated in the region of today's Arava Valley. Till %5 Ma ago there might have been other, now inactive fault traces in the vicinity of the present day AF that took up lateral motion. Together with a rearrangement of plates %5 Ma ago, the main fault trace shifted then to the position of today's AF.

Shallow architecture of the Wadi Araba fault (Dead Sea Transform) from high-resolution seismic investigations

“…They are observed at the southern part of the WAF (Shtivelman et al, 1998;Zilberman et al, 2005), at the eastern branches of the DST in Israel (Frieslander, 2000) and also in the study area (Kesten, 2004;Kesten et al, 2006). However, the structures in the western north-central Arava valley (i.e., the WAF and the faults in its direct vicinity) do not show 16 a c c e p t e d the normal component as the faults in the eastern Arava valley (Frieslander, 2000).…”

“…Toward the center of the Arava valley there are indications of more North-South striking 6 a c c e p t e d faults which often join at depth to form negative flower structures (Frieslander, 2000;Kesten et al, 2006). Several industrial seismic profiles and the DESERT NVR profile reveal the subsurface at the eastern side of the valley (Kesten, 2004;Kesten et al, 2006;DESERT Team, 2004). Here, the Wadi Arava fault (WAF), which is considered to be the main active strike-slip fault strand of the DST, can be seen in the seismic images, however, with varying clarity.…”

“…Indications of further near vertical faults and flower structures between Zofar fault and WAF are found on individual profiles. East of the WAF late Proterozoic igneous rocks, Cretaceous marine sediments and Paleozoic to early Cretaceous sandstones are exposed (Kesten et al, 2006). More faults sub-parallel to the WAF are known at distances around 10 km to the East (Quaira fault) (Kesten, 2004;Atallah, 1992).…”

“…In the uppermost kilometer West of the Zofar fault, Cretaceous and Permian rocks are found, while younger strata related with the Dead Sea basin are exposed East of it (e.g., Ritter et al, 2003). Toward the center of the Arava valley there are indications of more North-South striking 6 a c c e p t e d faults which often join at depth to form negative flower structures (Frieslander, 2000;Kesten et al, 2006). Several industrial seismic profiles and the DESERT NVR profile reveal the subsurface at the eastern side of the valley (Kesten, 2004;Kesten et al, 2006;DESERT Team, 2004).…”

4D analogue modelling of transtensional pull-apart basins

“…5b). Recent mapping using gravity (ten Brink et al, 1999) and remote sensing (Kesten et al, 2008) of this area reveals a string of long and narrow buried basins offset en-echelon by shorter (25-55 km), discontinuous fault segments. In contrast, the PDZs at the northern and southern boundaries of the Dead Sea are narrower and predominantly zones of strike-slip.…”