Contrasting fluid regimes along the Dead Sea Transform

Fault-related veins and cements from two segments [Arava Fault (AF), Ghab Fault (GF)] and one branch [Serghaya Fault (SF)] of the major transform plate boundary between Africa and the Arabian plate, the Dead Sea Transform, were investigated geochemically. The results document considerable differences in the nature and degree of fluid–rock interactions among these faults. Within the area of the AF, fluid activity has neither led to intensive exchange reactions between fluids and rocks nor to notable cementation of the fault damage zones. Strontium and carbon and oxygen isotopes indicate infiltration of predominantly descending (meteoric water) and only subordinate involvement of ascending hydrothermal fluids from deep sources. For the SF, fluid-enhanced weakening mechanisms (chemical alteration processes) and fracture cementation are dominant. Along the GF, alteration processes and fracture healing by cementation are more intense than in the AF, but less intense than in the SF branch. For the SF and GF, δ18O, strontium isotopes, and major and minor element contents of veins indicate (i) near-surface, low-temperature meteoric fluids that show little or no interaction with carbonate host rocks; and (ii) meteoric fluids that were buffered by the surrounding host rocks. We suggest that the contrasting fluid–rock interactions along the Dead Sea Transform are related to local variations in climate (precipitation).