We analyzed maze caves and the associated hydrogeology in the northern Negev–Judean Desert in Israel to provide insight on fluid migration and porosity development, with relevance to groundwater and petroleum reservoirs on the Arabian Platform flanks. The caves occur specifically in the arid region of the southern Levant, with no equivalent in the moister climate areas further to the north. The karstified bedrock consists of Upper Cretaceous epicontinental carbonates. Caves were formed mainly above deep faults associated with the Syrian arc fold system. Hypogenic flow is shown to have formed the maze caves particularly under the confinement of thick chalk and marl cap rock. Speleogenesis occurred during the Oligocene– early Miocene when the Afro-Arabian dome was rising and became erosionally truncated. Calcite deposits depleted in O point to a connection between the caves and recharge over far-field Nubian Sandstone outcrops, north of the Precambrian basement outcrops on the eastern side of the Red Sea. During the early–middle Miocene, the Dead Sea rift began dissecting the region, forming a deep endorheic depression at the eastern margin of the study area and disconnecting the far-field groundwater flow. This was followed by subsiding groundwater levels and associated dewatering of the caves. Fault escarpments and canyon downcutting then dissected the caves, forming the present entrances. The caves are currently mostly dry, with scarce speleothem occurrences. Gypsum crusts with δ34SSO4 values lower than other sulfate deposits point to bacterial sulfur reduction, hydrogen sulfide, and sulfuric acid being involved in the speleogenesis.
Bibliographical noteFunding Information:
The Israel Ministry of Science funded the project. Avner Ayalon, from the Israel Geological Survey, Zeev Aizenshtat, from the Department of Organic Chemistry and Casali Institute, The Hebrew University, Jerusalem, and Ward Said-Ahmad, from the Institute of Earth Sciences, The Hebrew University, Jerusalem, performed isotopic analysis. The Israel Cave Research Center team assisted with cave surveys. Roi Porat led the archaeological cave survey along the Dead Sea, finding previously unknown caves. Rachel Evans of Shell Exploration, Haim Gvirtzman of the Hebrew University, and Zohar Gvirtzman, Oded Bar, and Ezra Zilberman of the Israel Geological Survey assisted with fruitful discussions. Alexander Klimchouk and Jo De Waele are thanked for deep and constructive reviews.
© 2017 Geological Society of America