Subaqueous artesian springs and associated spring pits in a Himalayan pond |
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| Authors: | ERICH DRAGANITS CHRISTOPH JANDA |
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| Institution: | Institut für Geologie, Universität Wien, Althanstrasse 14, A-1090 Wien, Austria;Institut für Geologie, Universität Wien, Althanstrasse 14, A-1090 Wien, Austria |
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| Abstract: | Subaqueous, bowl-shaped depressions found in a Himalayan pond formed in an abandoned river channel in the Lingti Valley (Spiti, NW India) are spring pits (Quirke 1930 ). The occurrence of the spring pits is restricted to the western end of the pond, where coarse-grained, highly permeable alluvial fan material continues below lacustrine mud deposits. The spring pits formed by active vertical discharge of ground water from an underlying artesian alluvial fan aquifer, confined by the overlying fine-grained lacustrine sediments. The aquifer is continuously recharged by down-slope ground-water flow in the alluvial fan. These small artesian springs are comparable with much larger artesian springs described in the literature and a similar mechanism of formation is proposed. Some similarities in their shapes and mechanisms of formation may indicate that spring pits represent small, nearshore examples of pockmarks. The differences of these features, formed by persistent fluidization from short-lived seismic liquefaction processes, are discussed and the utility of the structures for palaeo-environmental and palaeo-ground-water interpretation is evaluated. |
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