The unique geomorphology of submarine venting features as revealed by dropping lake levels in the Dead Sea 

Abstract

The presence of submarine springs and seepages within the hypersaline Dead Sea appears to be a common feature. Hydrothermal fluid escape was first proposed in the mid-1980s based on temperature anomalies measured in the lake, and acoustic blanking observed on high-resolution seismic reflection data. However, the actual existence of such springs was not verified until recently, since the phenomenon only became the focus of dedicated scientific studies during the last decade. As a result of combined anthropogenic intervention and climate change, lake levels have been dropping since the 1960s by over 1 m per year. This has led to large expanses of the lake floor becoming dry land and for submarine springs and other venting features that were previously in deeper water to become shallower. As a consequence, such features are now accessible for direct study either by skilled scuba divers or even along the coast where some have become exposed. Underwater observations include pockmark-like structures, fast and slow-flowing springs, and even salt chimneys formed when brines with different ionic composition than Dead Sea water escape from these vents and come in contact with chlorine-saturated hypersaline background brine leading to the precipitation of halite and other minerals. Diverse microbial communities seem to thrive at these venting locations. Here we will discuss the different types of features, their connection to regional tectonics, and their evolution and development from water to land.