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3009976 
Journal Article 
Sagging and collapse sinkholes over hypogenic hydrothermal karst in a carbonate terrain 
Frumldn, A; Zaidner, Y; Na'aman, I; Tsatskin, A; Porat, N; Vulfson, L 
2015 
Yes 
Geomorphology
ISSN: 0169-555X 
229 
45-57 
WOS:000348017100005 
We show that clusters of karst sinkholes can occur on carbonate hypogene karst terrains. Unlike common doline karst of dissolution origin, the studied sinkholes form mainly by sagging and collapse. Thermal survey, OSL dating and morphologic analysis during quarrying and excavations are applied to study the sinkholes at the Ayyalon karst, Israel. The thermal survey shows the spatial pattern of rising warm water plumes, whose temperature is > 2 degrees C warmer than the surrounding aquifer water. These plumes dissolve the limestone, creating large voids and maze caves. Mass wasting forms surface sinkholes mainly by sagging and collapse. Both types of deformation often occur within the same depression. Lack of hydrologic connection between the surface and underground voids constrain drainage and promote rapid accumulation of colluvium, dust and pedogenic clays. These have filled the sinkholes up to their rim before the late Holocene. OSL dating constrains the rate of sediment accumulation within the sinkholes. The average filling rate (thickness divided by elapsed time) is similar to 47 mm ka(-1) for the last 53 +/- 4 ka in Sinkhole 1, while in Sinkhole 2 ("Nesher Ramla karst depression"), the rate is similar to 61 mm ka(-1) from similar to 200 to 78 ka, and similar to 173 mm ka(-1) since similar to 78 ka. Between similar to 170 and 78 ka, Sinkhole 2 was intensively used by Middle Paleolithic hominins. The studied sinkholes may be considered as a type locality for hypogene sinkhole terrain on carbonate rocks. (C) 2014 Elsevier B.V. All rights reserved. 
Paleosinkholes; Sagging; Collapse; Confined caves; Dissolution; Rising water plumes