NEW INSIGHTS INTO SALT WEATHERING FROM CRACKED BOULDERS IN HOLOCENE ALLUVIAL TERRACES INSIDE A CAVE, ALONG THE DEAD SEA RIFT VALLEY, SOUTHEAST ISRAEL

Association of salts with weathering of surface rocks is commonly observed in many terrestrial environments. Yet, the specific mechanisms that drive the broadly defined term of ‘salt-weathering’ are not fully understood. Here we present a study of intensely cracked alluvial boulders (primarily carbonates and chert) in a Holocene vadose piping cave formed within the Sodom salt diaper in the Dead Sea Rift Valley, southeastern Israel). Cracking of boulders in the cave environment where small diurnal-annual temperature fluctuation, i.e., ±0.5 and ±4 °C, respectively, imply negligible thermally induced stress facilitated unprecedented examination of the possible roles of stress associated with salt crystallization. Detailed field work and continuous temperature and relative humidity (RH) measurements conducted over the course of 9 months revealed that RH changes in the cave air facilitated multiple cycles of salt deliquescence-efflorescence and that these cycles appear to be the most-likely source for the stress required to physically shatter rocks in the cave environment. Our results point towards the potentially substantial role of the deliquescence/efflorescence mechanism in the otherwise broadly defined term of ‘salt weathering’.