64 research outputs found
Deformation of intrasalt beds recorded by magnetic fabrics
Funding Information Israel Science Foundation (ISF). Grant Number: 868/17 Israeli Government. Grant Number: 40706 Israel Science Foundation. Grant Number: 868/17Peer reviewedPublisher PD
Geometry and subsidence history of the Dead Sea basin : a case for fluid-induced mid-crustal shear zone?
This paper is not subject to U.S. copyright. The definitive version was published in Journal of Geophysical Research 117 (2012): B01406, doi:10.1029/2011JB008711.Pull-apart basins are narrow zones of crustal extension bounded by strike-slip faults that can serve as analogs to the early stages of crustal rifting. We use seismic tomography, 2-D ray tracing, gravity modeling, and subsidence analysis to study crustal extension of the Dead Sea basin (DSB), a large and long-lived pull-apart basin along the Dead Sea transform (DST). The basin gradually shallows southward for 50 km from the only significant transverse normal fault. Stratigraphic relationships there indicate basin elongation with time. The basin is deepest (8–8.5 km) and widest (~15 km) under the Lisan about 40 km north of the transverse fault. Farther north, basin depth is ambiguous, but is 3 km deep immediately north of the lake. The underlying pre-basin sedimentary layer thickens gradually from 2 to 3 km under the southern edge of the DSB to 3–4 km under the northern end of the lake and 5–6 km farther north. Crystalline basement is ~11 km deep under the deepest part of the basin. The upper crust under the basin has lower P wave velocity than in the surrounding regions, which is interpreted to reflect elevated pore fluids there. Within data resolution, the lower crust below ~18 km and the Moho are not affected by basin development. The subsidence rate was several hundreds of m/m.y. since the development of the DST ~17 Ma, similar to other basins along the DST, but subsidence rate has accelerated by an order of magnitude during the Pleistocene, which allowed the accumulation of 4 km of sediment. We propose that the rapid subsidence and perhaps elongation of the DSB are due to the development of inter-connected mid-crustal ductile shear zones caused by alteration of feldspar to muscovite in the presence of pore fluids. This alteration resulted in a significant strength decrease and viscous creep. We propose a similar cause to the enigmatic rapid subsidence of the North Sea at the onset the North Atlantic mantle plume. Thus, we propose that aqueous fluid flux into a slowly extending continental crust can cause rapid basin subsidence that may be erroneously interpreted as an increased rate of tectonic activity.Fieldwork was funded by U.S. AID Middle
Eastern Regional Cooperation Program grant M21–012, with in-kind contributions
by Al-Balqa’ Applied University (Jordan), the Geophysical Institute
of Israel, and the U.S. Geological Survey
Recommended from our members
Quaternary rise of the Sedom diapir, Dead Sea basin
Mount Sedom is the surface expression of a salt diapir that has emerged since the Pleistocene in the southwestern part of
the Dead Sea basin. Milestones in the uplift history of the Sedom salt diapir since its inception were deduced from angular
and erosional unconformities, thickness variations, caprock formation, chemistry and isotope composition of lacustrine aragonite,
cave morphology, precise leveling, and satellite geodesy. Thickness variations of the overburden observed in transverse seismic
lines suggest that significant growth of the Sedom diapir may have initiated only after this thickness exceeded ∼2400 m in
the Late Pliocene. The formation of the caprock signifies the arrival of the Sedom diapir from depth to the dissolution level
between 300,000–100,000 yr B.P. During this period and later, angular and erosional unconformities in the upper part of the
overburden near Mount Sedom are attributed to the piercing diapir. Rapid solution of rock salt from parts of Mount Sedom inundated
by Lake Lisan after ca. 40,000 yr B.P. is inferred from Na/Ca ratios in aragonite and their relation to δ 13 C. On the mountain itself, the older parts (70,000–43,000 yr B.P.) of the lacustrine Lisan Formation are missing. The top
of the preserved sediments is covered by alluvial sediments that must have been deposited when the elevation of Mount Sedom
was not higher than 265 m below sea level (mbsl) at ca. 14,000 yr B.P. The present elevation of these sediments at 190 mbsl
indicates an average uplift rate of ∼5 mm/yr over the past 14,000 yr. Similar uplift rates of 6–9 mm/yr are inferred for the
Holocene from displacement of the “salt mirror” and hanging passages of caves. The present uplift rate, calculated from precise
leveling and interferometric synthetic aperture radar (InSAR), is similar to the average Holocene rate. Based on the gathered
data, we reconstruct the topographic rise of Sedom diapir and its relation to lake level variations during the late Pleistocene
and Holocene
Methane Hydrate Stability and Potential Resource in the Levant Basin, Southeastern Mediterranean Sea
- …