Late Cenozoic mafic lavas crop out locally along the Jordan rift. Some of these lavas are spatially associated with thermal springs, and this association has prompted some workers to hypothesize that the hot water derives its thermal energy from the shallow, still hot intrusive roots of the volcanic rocks. However, all of the volcanic rocks appear to represent mantle-derived mafic magma that rose rather quickly to the Earth's surface, without filling crustal reservoirs within which differentiation would have produced evolved, derivative products. Moreover, the lavas are too old and of too small a volume to represent the surface expression of an active reservoir of magma within the crust. These interpretations of the volcanic geology are consistent with conclusions drawn from the chemistry of the thermal water; the water has equilibrated with host rocks at no more than 110??C, probably at depths of 2-3 km. Thus, thermal springs along the Jordan rift appear to reflect heating during circulation through a regional regime of average crustal heat flow (Galanis et at., 1986). The magmatic activity may only be a second or third order contributor to this heat flow. ?? 1988.
Additional Publication Details
KAr ages, chemical composition and geothermal significance of cenozoic basalt near the Jordan rift