Please use this identifier to cite or link to this item: https://www.um.edu.mt/library/oar/handle/123456789/93097
Title: Groundwater seepage is a key driver of theater-headed valley formation in limestone
Authors: Micallef, Aaron
Saadatkhah, Nader
Spiteri, Jurgen
Rizzo, Enzo
Capozzoli, Luigi
De Martino, Gregory
Pace, Letizia
Burrill, Christine
Gatt, Michael
Schmidt, Mark
Gupta, Shubhangi
Keywords: Remote sensing -- Malta
Ġnejna Bay (Mġarr, Malta)
Environmental monitoring
Sediments (Geology)
Oceanography
Marine sediments
Geomorphology
Sedimentology
Limestone
Issue Date: 2022
Publisher: Geological Society of America
Citation: Micallef, A., Saadatkhah, N., Spiteri, J., Rizzo, E., Capozzoli, L., De Martino, G., ... & Gupta, S. (2022). Groundwater seepage is a key driver of theater-headed valley formation in limestone. Geology, 50.
Abstract: Groundwater seepage leads to the formation of theater-headed valleys (THVs) in unconsolidated sediments. In bedrock, the role of groundwater in THV development remains disputed. Here, we integrate field and remote-sensing observations from Gnejna Valley (Maltese Islands) with numerical modeling to demonstrate that groundwater seepage can be the main driver of THV formation in jointed limestone overlying clays. The inferred erosion mechanisms entail (1) widening of joints and fractures by fluid pressure and dissolution and (2) creeping of an underlying clay layer, which lead to slope failure at the valley head and its upslope retreat. The latter is slower than the removal of the talus by creep and sliding on the valley bed. The location and width of THVs are controlled by the location of the master fault and the extent of the damage zone, respectively. The variability of seepage across the fault zone determines the shape of the valley head, with an exponential decrease in seepage away from the fault giving rise to a theater-shaped head that best matches that of Gnejna Valley. Our model may explain the formation of THVs by groundwater in jointed, strong-over-weak chemical sedimentary lithologies, particularly in arid terrestrial settings.
URI: https://www.um.edu.mt/library/oar/handle/123456789/93097
Appears in Collections:Scholarly Works - FacSciGeo



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