Paleomagnetic reconstruction of a diapir emplacement: A case study from Sedom diapir, the Dead Sea Rift

Reconstructing the emplacement path of a diapiric sequence is relatively complex, in part because the stratigraphic (top versus bottom) sense of the sequence can be obscured by the complex structure. Paleomagnetic study of the diapiric sequence may reveal simultaneously three characteristics of it: (1) the stratigraphic sense, (2) the three-dimensional rotation path of the tilted sequence, and (3) the magnetic polarity of the sequence. We apply paleomagnetism to reconstruct the emplacement path of the Sedom diapir in the Dead Sea Rift, Israel. This application resolves the ambiguity regarding the geometrical orientation of the thickest intrarift stratigraphic section (2 km) exposed in the Dead Sea region. We here report the natural remanent magnetization for 172 oriented samples (mainly dolomite and siltstone) from seven localities in the steeply inclined beds of the Sedom diapir. A fold test, as well as other field and laboratory tests, shows that the characteristic remanent magnetization (ChRM) component of the rocks was acquired before the tilting of the Sedom sequence, whereas the low-coercivity magnetic component of probably chemical remanent magnetization origin was acquired after the tilting. This low-coercivity (secondary) component, likely acquired in the Brunhes Normal chron, records up to 40° young counterclockwise rotation about a vertical axis. The ChRM and secondary components (together with the bedding plane) were restored to their expected (original) position by rotating them about horizontal, vertical, or inclined axes to get the complete three-dimensional rotation path. The resulting structure of the southern Sedom diapir is composed of a thin western "salt wall" that is juxtaposed against a thick eastern salt wall. In the northern part of the mountain apparently only the thick eastern salt wall is exposed.