Sea level is the base level for groundwater circulation in coastal aquifers. In carbonate coastal aquifers, sea-level changes and tectonics have conditioned in geological times the evolution of karstic landforms and underground drainage systems. The study evaluated the quantifiable effects of such phenomena in the Murgia karstic coastal aquifer of the Apulia region (Southern Italy). The Murgia plateau is a structural high, which inner portion (High Murgia) has an elevation ranging from 686 to 450 m a.s.l.. It consists of a powerful succession of Cretaceous limestone, with small extension covers of Late Pliocene to Quaternary sedimentary formations. The Murgia current morpho-structural setting is the result of both tectonic events and glacio-eustatic sea-level changes. The most important morphogenetic factor has been the karstification. Surface and underground karstic forms are differently distributed and evolved over the Murgia territory, as a result of different lithology and intensity of karst phenomena. The repeated and significant changes of groundwater level consequent to “sea-level changes” have driven the karst processes, which resulted in a multiphase karst and continuous evolution of the karstic drainage system, with periods of slowing or reactivation of speleogenetic activity, facilitated or hindered by the accumulation of “terra rossa”. The topographic surface of Murgia was subject to a morphometric analysis by GIS application, aiming at identifying the flat or low topographic gradient surfaces. The elevation of identified surfaces was compared to the elevation of characteristic karstic levels recognized in 140 inland caves and 85 vertical conduits. The agreement between the elevations indicated by morphometric analysis and those identified by high frequency of characteristics karstic levels allows hypothesizing the elevations of 620, 600, 425, 385, 355, 315, 270, 250, 205, 180, 150, 110, and 70 m a.s.l. as those of the more probable past sea-level stands.
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|Titolo:||Sea level stands, karst hydrology and morphologies through morphometric analysis in the Murgia Plateau (Apulia, Southern Italy)|
|Data di pubblicazione:||2010|
|Appare nelle tipologie:||3.1 Monografia o trattato scientifico|